WO2024024951A1 - Binder composition for secondary battery, electrode sheet and secondary battery, and method for producing electrode sheet and secondary battery - Google Patents

Binder composition for secondary battery, electrode sheet and secondary battery, and method for producing electrode sheet and secondary battery Download PDF

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WO2024024951A1
WO2024024951A1 PCT/JP2023/027794 JP2023027794W WO2024024951A1 WO 2024024951 A1 WO2024024951 A1 WO 2024024951A1 JP 2023027794 W JP2023027794 W JP 2023027794W WO 2024024951 A1 WO2024024951 A1 WO 2024024951A1
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water
secondary battery
soluble polymer
group
active material
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PCT/JP2023/027794
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French (fr)
Japanese (ja)
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和博 ▲濱▼田
祥平 片岡
景 河野
浩徳 水田
悟郎 森
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富士フイルム株式会社
富士フイルム和光純薬株式会社
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Publication of WO2024024951A1 publication Critical patent/WO2024024951A1/en

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    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
    • C08F20/00—Homopolymers and copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and only one being terminated by only one carboxyl radical or a salt, anhydride, ester, amide, imide or nitrile thereof
    • C08F20/02—Monocarboxylic acids having less than ten carbon atoms, Derivatives thereof
    • C08F20/52—Amides or imides
    • C08F20/54—Amides, e.g. N,N-dimethylacrylamide or N-isopropylacrylamide
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L101/00—Compositions of unspecified macromolecular compounds
    • C08L101/12—Compositions of unspecified macromolecular compounds characterised by physical features, e.g. anisotropy, viscosity or electrical conductivity
    • C08L101/14—Compositions of unspecified macromolecular compounds characterised by physical features, e.g. anisotropy, viscosity or electrical conductivity the macromolecular compounds being water soluble or water swellable, e.g. aqueous gels
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/134—Electrodes based on metals, Si or alloys
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/139—Processes of manufacture
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/139—Processes of manufacture
    • H01M4/1395—Processes of manufacture of electrodes based on metals, Si or alloys
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/38—Selection of substances as active materials, active masses, active liquids of elements or alloys
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Definitions

  • the present invention relates to a binder composition for a secondary battery, an electrode sheet, a secondary battery, and a method for manufacturing these electrode sheets and secondary batteries.
  • Secondary batteries typified by lithium ion secondary batteries, are used as a power source for portable electronic devices such as personal computers, video cameras, and mobile phones. Recently, against the backdrop of the global environmental challenge of reducing carbon dioxide emissions, they have become popular as a power source for transportation equipment such as automobiles, and as a storage device for nighttime electricity, electricity generated from natural energy, etc.
  • the electrodes (positive electrode and negative electrode) of a lithium ion secondary battery have electrode active material layers (positive electrode active material layer and negative electrode active material layer), and this electrode active material layer is capable of intercalating and releasing lithium ions during charging and discharging.
  • Electrode active materials, conductive aids, etc. are so-called solid particles, and due to expansion and contraction of electrode active material particles associated with charging and discharging (intercalation and release of lithium ions) of a lithium ion secondary battery, the conductivity between solid particles is impaired. Cheap. If the conduction state is impaired, the internal resistance of the battery increases and the battery capacity decreases.
  • Patent Document 1 describes a binder composition for a lithium ion secondary battery electrode that includes a particulate polymer and a water-soluble polymer.
  • Patent Document 1 discloses that the water-soluble polymer constituting this composition comprises an ethylenically unsaturated carboxylic acid monomer unit, (meth)acrylamide, N-2-dimethylaminoethyl (meth)acrylamide, and N-2-dimethylaminoethyl (meth)acrylamide.
  • the volume of the negative electrode active material changes greatly during charging and discharging, and the electrical conductivity between so-called solid particles such as the electrode active material and the conductive agent ( Since the adhesion state is likely to be impaired, battery performance is likely to deteriorate due to repeated charging and discharging. In other words, there are restrictions on improving cycle characteristics.
  • the present inventors have conducted studies and found that when conventional electrode binders such as the binder described in Patent Document 1 are used, the resulting secondary batteries, especially silicon-based batteries that have a large volumetric change during charging and discharging. It has been found that the cycle characteristics of secondary batteries using active materials as negative electrode active materials are not sufficient.
  • the present invention provides a secondary battery that can sufficiently improve the cycle characteristics (sufficiently extend the cycle life) of the obtained secondary battery even when using an electrode active material that exhibits a large volume change during charging and discharging.
  • An object of the present invention is to provide a binder composition. Furthermore, an object of the present invention is to provide an electrode sheet and a secondary battery using the binder composition for a secondary battery. Furthermore, it is an object of the present invention to provide a method for manufacturing the above electrode sheet and secondary battery.
  • R 21 to R 23 represent a hydrogen atom, a cyano group, or an alkyl group having 1 to 6 carbon atoms
  • R 24 represents a hydrogen atom, an acyl group, a hydroxy group, a phenyl group, or a carboxy group
  • L 21 represents a single bond, an alkylene group having 1 to 16 carbon atoms, an arylene group having 6 to 12 carbon atoms, an oxygen atom, a sulfur atom, a carbonyl group, an imino group, or a linking group combining these.
  • * indicates a binding site for incorporation into the main chain of the water-soluble polymer (X).
  • ⁇ 5> The binder composition for a secondary battery according to any one of ⁇ 1> to ⁇ 4>, wherein the water-soluble polymer (X) has a weight average molecular weight of 10,000 to 1,000,000.
  • ⁇ 6> The binder composition for a secondary battery according to any one of ⁇ 1> to ⁇ 5>, wherein the water-soluble polymer (X) has a molecular weight distribution of 5.0 or less.
  • ⁇ 7> The binder composition for a secondary battery according to any one of ⁇ 1> to ⁇ 6>, wherein the water-soluble polymer (Y) is a polysaccharide.
  • ⁇ 8> The binder composition for a secondary battery according to ⁇ 7>, wherein the water-soluble polymer (Y) contains at least one of carboxymethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, and xanthan gum.
  • Y contains at least one of carboxymethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, and xanthan gum.
  • ⁇ 9> The binder composition for a secondary battery according to any one of ⁇ 1> to ⁇ 8>, wherein the water-soluble polymer (Y) has a weight average molecular weight of 100,000 to 500,000.
  • ⁇ 10> The binder composition for a secondary battery according to any one of ⁇ 1> to ⁇ 9>, which contains polymer particles.
  • the polymer constituting the polymer particles is a polymer containing at least one of a conjugated diene component, an ethylenically unsaturated carboxylic acid component, a cyano group-containing ethylenic monomer component, and an aromatic vinyl monomer component.
  • a binder composition for secondary batteries as described in . ⁇ 12> The binder composition for a secondary battery according to any one of ⁇ 1> to ⁇ 11>, which contains water.
  • ⁇ 14> The binder composition for a secondary battery according to ⁇ 13>, wherein the active material includes a silicon-based active material.
  • ⁇ 16> A secondary battery, wherein at least one of the positive electrode active material layer and the negative electrode active material layer is a layer formed using the binder composition for a secondary battery according to ⁇ 13> or ⁇ 14>.
  • ⁇ 17> A method for manufacturing an electrode sheet, comprising forming an electrode active material layer using the binder composition for secondary batteries according to ⁇ 13> or ⁇ 14>.
  • ⁇ 18> A method for manufacturing a secondary battery, comprising incorporating an electrode sheet obtained by the manufacturing method according to ⁇ 17> as an electrode of a secondary battery.
  • water-soluble polymer means a polymer whose solubility in water is 10 g/L-H 2 O or more at 20°C, that is, a polymer that dissolves 10 g or more in 1 liter of water at 20°C. do.
  • the solubility of the "water-soluble polymer” is preferably 100 g/L-H 2 O or more.
  • a numerical range expressed using " ⁇ " means a range that includes the numerical values written before and after " ⁇ " as lower and upper limits.
  • the expression of a compound, a constituent component, or a substituent is meant to include those whose structures are partially changed within the range that exhibits the effects of the present invention.
  • substituents e.g., groups expressed as "alkyl group,””methylgroup,””methyl,” etc.
  • linking groups e.g., "alkylene group,”"methylenegroup,””methylenegroup,” etc.
  • substituents e.g., groups expressed as "alkyl group,”"methylgroup,””methyl,” etc.
  • substituents e.g., groups expressed as "alkyl group,”"methylgroup,””methyl,” etc.
  • linking groups e.g., “alkylene group,”"methylenegroup,””methylenegroup,” etc.
  • substituents in the present invention are substituents selected from substituent group T described below.
  • substituents, etc. when there are multiple substituents or linking groups, etc. (hereinafter referred to as substituents, etc.) indicated by a specific symbol or formula, or when multiple substituents, etc.
  • each substituent, etc. may be the same or different from each other. This also applies to the constituent components of the polymer.
  • one type of each component may be contained, or two or more types of each component may be contained.
  • (meth)acrylic means one or both of acrylic and methacrylic. The same applies to (meth)acrylate.
  • the term "secondary battery" refers to any device in which ions pass between positive and negative electrodes via an electrolyte during charging and discharging, and energy is stored and released at the positive and negative electrodes.
  • the term "secondary battery” includes both a battery and a capacitor (for example, a lithium ion capacitor). From the viewpoint of energy storage capacity, the secondary battery of the present invention is preferably used for battery applications (not as a capacitor). Secondary batteries can be roughly classified into aqueous secondary batteries and non-aqueous secondary batteries depending on the electrolyte used, and in the present invention, non-aqueous secondary batteries are preferred.
  • aqueous secondary battery refers to a secondary battery using an aqueous electrolyte as an electrolyte.
  • non-aqueous secondary battery includes non-aqueous electrolyte secondary batteries and all-solid-state secondary batteries.
  • a “non-aqueous electrolyte secondary battery” means a secondary battery using a non-aqueous electrolyte as an electrolyte.
  • the term “non-aqueous electrolyte” means an electrolyte that does not substantially contain water.
  • An electrolytic solution that does not substantially contain water means that the "non-aqueous electrolytic solution” may contain a trace amount of water as long as it does not impede the effects of the present invention.
  • the "nonaqueous electrolyte” has a water concentration of 200 ppm or less (based on mass), preferably 100 ppm or less, and more preferably 20 ppm or less.
  • the term "all-solid secondary battery” refers to a secondary battery that uses a solid electrolyte such as an inorganic solid electrolyte or a solid polymer electrolyte without using a liquid as an electrolyte.
  • this number of carbon atoms means the number of carbon atoms in the group itself unless otherwise specified in the present invention or this specification.
  • this group further has a substituent, it means the number of carbon atoms not including the number of carbon atoms of this substituent.
  • the "solid content” used when describing the content or content ratio means components other than water and the liquid medium described below.
  • the binder composition and electrode sheet for a secondary battery of the present invention can sufficiently extend the cycle life of the resulting secondary battery even when an electrode active material that exhibits a large volume change during charging and discharging is used.
  • the secondary battery of the present invention can achieve a sufficiently long cycle life even when using an electrode active material that exhibits a large volume change during charging and discharging. According to the method for manufacturing an electrode sheet of the present invention, the above electrode sheet of the present invention can be obtained. Moreover, according to the method for manufacturing a secondary battery of the present invention, the above-mentioned secondary battery of the present invention can be obtained.
  • FIG. 1 is a vertical cross-sectional view schematically showing the basic stacked structure of an embodiment of a secondary battery according to the present invention.
  • the binder composition for secondary batteries of the present invention includes a water-soluble polymer (X) and a water-soluble polymer (Y), and the water-soluble polymer (X) is a polymer containing 20% by mass or more of a component represented by the general formula (B-2) described below, and the water-soluble polymer ( The weight average molecular weight ratio of Y) is 0.300 to 10.0.
  • the binder composition of the present invention is preferably used for forming members or constituent layers constituting a non-aqueous secondary battery, more preferably a non-aqueous electrolyte secondary battery.
  • the binder composition of the present invention preferably contains water as the liquid medium.
  • the binder composition of the present invention can be suitably used for forming an electrode active material layer in an electrode (positive electrode or negative electrode) of a secondary battery.
  • the binder composition of the present invention may contain an electrode active material (a positive electrode active material or a negative electrode active material, together referred to simply as "active material") to activate the electrode (positive electrode or negative electrode) of a secondary battery. It can be used to form a material layer.
  • the water-soluble polymer (X) contained in the binder composition of the present invention and the below-mentioned polymer particles which may be contained in the binder composition of the present invention can be combined with the binder composition of the present invention and solid particles (electrode It is thought that in the layer formed by mixing the solid particles (active material, conductive aid, etc.), it functions mainly as a binding agent (binder) that binds these solid particles together. It can also function as a binder that binds the current collector and solid particles.
  • the adsorption of water-soluble polymer (X) and polymer particles to solid particles and current collectors includes not only physical adsorption but also chemical adsorption (adsorption due to chemical bond formation, adsorption due to exchange of electrons, etc.).
  • the water-soluble polymer (Y) contained in the binder composition of the present invention is considered to mainly function as a thickener (dispersant) in the binder composition of the present invention.
  • the binder composition of the present invention can improve the cycle characteristics of a secondary battery by, for example, producing an electrode sheet in a form containing an active material and applying this to an electrode of a secondary battery. Although the reason for this is not certain, it is thought to be as follows.
  • the binder composition of the present invention is thickened by containing the water-soluble polymer (Y), and the dispersibility of the binder composition is improved. Therefore, even in the electrode active material layer formed using this binder composition, solid particles such as the water-soluble polymer (X), the water-soluble polymer (Y), and the active material are substantially uniformly dispersed. can exist.
  • the water-soluble polymer (X) contains 20% by mass or more of a component having a specific structure represented by the general formula (B-2) described below, and the weight average molecular weight of the water-soluble polymer (X) is
  • B-2 a component having a specific structure represented by the general formula (B-2) described below
  • the weight average molecular weight of the water-soluble polymer (X) is
  • the ratio of the weight average molecular weight of the water-soluble polymer (Y) to the water-soluble polymer (Y) is 0.300 to 10.0
  • the water-soluble polymer (X) and the water-soluble polymer ( Y) interaction is promoted, the fracture energy of the composite of water-soluble polymer (X) and water-soluble polymer (Y) is improved, and the binding properties of solid particles, etc. are also improved.
  • the ability to maintain a good conduction state even when the electrode active material changes in volume as the battery is charged and discharged is thought to be one of the reasons for improving the cycle characteristics of the secondary battery.
  • the water-soluble polymer (X) is a polymer containing 20% by mass or more of a component represented by the following general formula (B-2).
  • R 21 to R 23 represent a hydrogen atom, a cyano group, or an alkyl group having 1 to 6 carbon atoms.
  • This alkyl group having 1 to 6 carbon atoms may be linear or branched.
  • the alkyl group having 1 to 6 carbon atoms is preferably an alkyl group having 1 to 4 carbon atoms, more preferably methyl or ethyl, and even more preferably methyl.
  • a hydrogen atom is preferable as R 21 and R 22 .
  • R23 is preferably a hydrogen atom or a methyl group, more preferably a hydrogen atom.
  • R24 represents a hydrogen atom, an acyl group (alkylcarbonyl group), a hydroxy group, a phenyl group, or a carboxy group.
  • alkyl group in the acyl group include the alkyl group in the substituent group T described below, which may be straight chain or branched, and may be an alkyl group having 1 to 6 carbon atoms that can be taken as R 21 to R 23 . groups can be preferably employed.
  • R24 is preferably a hydrogen atom or a hydroxy group, more preferably a hydrogen atom.
  • R N represents a hydrogen atom or an alkyl group.
  • the chemical formula weight of L 21 is preferably from 14 to 2,000, more preferably from 14 to 500, even more preferably from 28 to 200.
  • the alkylene group having 1 to 16 carbon atoms that L 21 may have may be linear or branched.
  • the alkylene group preferably has 1 to 12 carbon atoms, more preferably 1 to 10 carbon atoms, even more preferably 1 to 6 carbon atoms, and particularly preferably 1 to 4 carbon atoms.
  • L 21 is preferably a single bond, methylene, ethylene, propylene, 2-hydroxypropylene or butylene, more preferably a single bond, ethylene group or butylene group, even more preferably a single bond or ethylene group, and particularly preferably a single bond.
  • * indicates a bonding site for incorporation into the main chain of the above polymer (water-soluble polymer (X)).
  • components represented by the above general formula (B-2) include (meth)acrylamide component; N-(hydroxyalkyl)(meth) such as N-(2-hydroxyethyl)(meth)acrylamide component; Acrylamide components are mentioned, (meth)acrylamide components are preferred, and acrylamide components are more preferred.
  • the water-soluble polymer (X) preferably contains a (meth)acrylamide component, and more preferably contains an acrylamide component, from the viewpoint of effectively suppressing the volume change of the electrode active material layer and improving cycle characteristics.
  • the content of the (meth)acrylamide component (preferably the acrylamide component) in the component represented by general formula (B-2) is preferably 50% by mass or more, more preferably 70% by mass or more, and 90% by mass or more. is more preferred, 95% by mass or more is particularly preferred, and may be 100% by mass.
  • the water-soluble polymer (X) used in the present invention may contain components other than those represented by the above general formula (B-2) within a range that does not impair the effects of the present invention.
  • a constituent component a constituent component represented by the following general formula (B-1), and acrylonitrile component, N-vinyl-2 as a constituent component different from the constituent component represented by the following general formula (B-1).
  • -pyrrolidone component and styrene component preferably includes at least one of an acrylonitrile component and an N-vinyl-2-pyrrolidone component, and more preferably an acrylonitrile component.
  • R 11 to R 13 represent a hydrogen atom, a cyano group, or an alkyl group having 1 to 6 carbon atoms.
  • This alkyl group having 1 to 6 carbon atoms may be linear or branched.
  • the alkyl group having 1 to 6 carbon atoms is preferably an alkyl group having 1 to 4 carbon atoms, more preferably methyl or ethyl, and even more preferably methyl.
  • a hydrogen atom is preferable as R 11 and R 12 .
  • R 13 is preferably a hydrogen atom or a methyl group, more preferably a hydrogen atom.
  • the alkyl group in the above alkoxy group having 1 to 6 carbon atoms may be linear or branched.
  • the alkoxy group having 1 to 6 carbon atoms is preferably an alkoxy group having 1 to 4 carbon atoms, more preferably methoxy or ethoxy.
  • R 14 is preferably a hydrogen atom, a hydroxy group, a methoxy group or an ethoxy group, and more preferably a hydrogen atom.
  • R N represents a hydrogen atom or an alkyl group.
  • L 11 represents a linking group other than a single bond
  • the chemical formula weight of L 11 is preferably from 14 to 2,000, more preferably from 14 to 500, even more preferably from 28 to 200.
  • the alkylene group having 1 to 16 carbon atoms that L 11 may have may be linear or branched.
  • the alkylene group preferably has 1 to 12 carbon atoms, more preferably 1 to 10 carbon atoms, even more preferably 1 to 6 carbon atoms, and particularly preferably 1 to 4 carbon atoms.
  • L 11 is preferably a single bond, methylene, ethylene, propylene, 2-hydroxypropylene or butylene, and more preferably a single bond, ethylene group or butylene group. * indicates a bonding site for incorporation into the main chain of the above polymer (water-soluble polymer (X)).
  • components represented by the above general formula (B-1) include (meth)acrylic acid component; methyl (meth)acrylate component, ethyl (meth)acrylate component, and propyl (meth)acrylate component. and alkyl (meth)acrylate components such as butyl (meth)acrylate components; 2-hydroxyethyl (meth)acrylate component, 4-hydroxybutyl (meth)acrylate component, 2,3-dihydroxypropyl (meth)acrylate component, etc.
  • hydroxyalkyl (meth)acrylate component examples include alkoxyalkyl (meth)acrylate components such as methoxyethyl (meth)acrylate component and ethoxyethyl (meth)acrylate component; (meth)acrylic acid component or hydroxyalkyl (meth)acrylate Ingredients are preferred.
  • the types of constituent components contained in the water-soluble polymer (X) are not particularly limited, and are preferably 1 to 10 types, more preferably 1 to 5 types, even more preferably 1 to 3 types, and 1 type or 2 types. is particularly preferred.
  • the water-soluble polymer (X) described below polymers having one or two types of constituent components are described.
  • the single component type polymer is polyacrylamide.
  • the content of the component represented by the above general formula (B-2) is 20% by mass or more, preferably 40% by mass or more, more preferably 60% by mass or more, It is more preferably 80% by mass or more, particularly preferably 85% by mass or more, particularly preferably 90% by mass or more, most preferably 95% by mass or more, and may be 100% by mass. There is no particular restriction on the upper limit, as long as it is 100% by mass or less.
  • the total content of the N-vinyl-2-pyrrolidone component and the styrene component is 80% by mass or less, preferably 60% by mass or less, more preferably 40% by mass or less, even more preferably 20% by mass or less, and 15% by mass or less. It is more preferably at most 10% by mass, even more preferably at most 5% by mass.
  • the water-soluble polymer (X) does not contain any of the components represented by the above general formula (B-1), an acrylonitrile component, an N-vinyl-2-pyrrolidone component, and a styrene component.
  • the weight average molecular weight (Mw) of the water-soluble polymer (X) used in the present invention is not particularly limited, and is preferably, for example, 10,000 to 1,000,000, and more preferably 100,000 to 900,000 from the viewpoint of improving cycle characteristics.
  • the lower limit is more preferably 200,000 or more, and even more preferably 300,000 or more.
  • the upper limit is more preferably 800,000 or less, and even more preferably 700,000 or less. It is preferable that the water-soluble polymer (X) does not have a crosslinked structure, that is, it is a chain polymer.
  • the molecular weight distribution of the water-soluble polymer (X) is preferably 5.0 or less.
  • the molecular weight distribution of the water-soluble polymer (X) is practically and preferably 1.0 or more, more preferably 1.5 or more, and even more preferably 2.0 or more.
  • the molecular weight distribution of the water-soluble polymer (X) is within the above-mentioned preferred range, variations in the molecular weight of the water-soluble polymer (X) can be suppressed, and the water-soluble polymer can contribute to improving the tensile modulus of the binder composition.
  • the cycle characteristics are further improved because the interaction between the molecule (X) and the water-soluble polymer (Y) is more likely to occur.
  • the molecular weight distribution of the water-soluble polymer (X) is also called the degree of dispersion, and is calculated by [weight average molecular weight (Mw)]/[number average molecular weight (Mn)].
  • the ratio (Y/X) of the weight average molecular weight of the water-soluble polymer (Y) described below to the weight average molecular weight of the water-soluble polymer (X) is 0.300 to 10.0. If Y/X is less than 0.300 or exceeds 10.0, the difference in weight average molecular weight between the water-soluble polymer (X) and the water-soluble polymer (Y) is too large. , because it is difficult to form sufficient intermolecular bonds such as hydrogen bonds between the water-soluble polymer (X) and the water-soluble polymer (Y). ) is considered to be due to insufficient interaction effects, resulting in poor cycle characteristics.
  • the upper limit of Y/X is preferably 7.00 or less, more preferably 6.00 or less, even more preferably 5.00 or less, and particularly preferably 4.00 or less. .
  • the above Y/X is preferably 1.50 to 10.0, more preferably 2.00 to 10.0.
  • the above Y/X is preferably 0.700 to 7.00, more preferably 1.00 to 5.00.
  • the above Y/X is preferably 0.350 to 5.00, more preferably 0.600 to 3.50.
  • the above Y/X is preferably 0.300 to 5.00, more preferably 0.350 to 4.00.
  • the above Y/X is preferably from 0.300 to 5.00, more preferably from 0.300 to 4.00. Note that the significant figures of Y/X above are 3 digits.
  • the weight average molecular weight and number average molecular weight of polymers such as water-soluble polymer (X) and water-soluble polymer (Y) are measured by gel permeation chromatography (GPC).
  • the molecular weight refers to the molecular weight in terms of polyethylene glycol.
  • the values are basically measured according to the method of measurement condition 1 below. However, depending on the type of polymer such as water-soluble polymer (X) and water-soluble polymer (Y), an appropriate eluent may be selected and used.
  • Measuring instrument HLC-8220GPC (product name, manufactured by Tosoh Corporation)
  • Carrier 200mM sodium nitrate aqueous solution Measurement temperature: 40°C Carrier flow rate: 1.0ml/min Sample concentration: 0.2% by mass Detector: RI (refractive index) detector If the molecular weight cannot be measured under measurement condition 1 above, such as when crosslinking occurs, the molecular weight is measured by static light scattering under measurement condition 2 below.
  • RI reffractive index
  • the tensile modulus of the water-soluble polymer (X) used in the present invention is preferably 3500 MPa or more, more preferably 4000 MPa or more, from the viewpoint of effectively suppressing the volume change of the electrode active material layer and improving cycle characteristics. , 5000 MPa or more is more preferable, and 6000 MPa or more is particularly preferable. On the other hand, the above tensile modulus is practically 15,000 MPa or less. In the present invention, the above tensile modulus is determined by using an aqueous solution of water-soluble polymer (X) instead of the binder composition to prepare a test piece in the method for calculating the tensile modulus of a binder composition described in Examples below. Everything else can be determined in the same way.
  • the water-soluble polymer (X) may further have a substituent in each structure or partial structure described above, and examples of the substituent include substituents selected from the substituent group T below. Moreover, regarding each substituent in the water-soluble polymer (X), unless otherwise specified, the description of the corresponding substituent in the substituent group T below can be applied. Regarding each linking group in the water-soluble polymer (X), unless otherwise specified, the description of the linking group obtained by removing hydrogen bonds from the corresponding substituent in substituent group T below can be applied.
  • T - Alkyl group preferably an alkyl group having 1 to 20 carbon atoms, such as methyl, ethyl, isopropyl, t-butyl, pentyl, heptyl, 1-ethylpentyl, benzyl, 2-ethoxyethyl, 1-carboxymethyl, etc.
  • Alkenyl group preferably an alkenyl group having 2 to 20 carbon atoms, such as vinyl, allyl, oleyl, etc.
  • alkynyl group preferably an alkynyl group having 2 to 20 carbon atoms, such as ethynyl, butadiynyl, phenylethynyl
  • cycloalkyl groups preferably cycloalkyl groups having 3 to 20 carbon atoms, such as cyclopropyl, cyclopentyl, cyclohexyl, 4-methylcyclohexyl, etc.
  • sulfamoyl (-SO 2 NH 2 ), N,N-dimethylsulfamoyl, N-phenylsulfamoyl, etc.), acyl groups (alkylcarbonyl group, alkenylcarbonyl group, alkynylcarbonyl group, arylcarbonyl group, and heterocycle) Acyl group containing a carbonyl group and preferably having 1 to 20 carbon atoms, such as formyl, acetyl, propionyl, butyryl, octanoyl, hexadecanoyl, acryloyl, methacryloyl, crotonoyl, benzoyl, naphthoyl, nicotinoyl, etc.), acyloxy group (Including alkylcarbonyloxy groups, alkenylcarbonyloxy groups, alkynylcarbonyloxy groups, arylcarbonyloxy groups and heterocyclic carbony
  • the acyl group in the acylamino group is preferably the above-mentioned acyl group.
  • acetylamino, benzoylamino, etc. an alkylthio group (preferably an alkylthio group having 1 to 20 carbon atoms, For example, methylthio, ethylthio, isopropylthio, benzylthio, etc.), arylthio group (preferably an arylthio group having 6 to 26 carbon atoms, such as phenylthio, 1-naphthylthio, 3-methylphenylthio, 4-methoxyphenylthio, etc.) , an arylsilyl group (preferably an arylsilyl group having 6 to 42 carbon atoms, such as triphenylsilyl), a heterocyclic thio group (a group in which an -S- group is bonded to the above heterocyclic group), an alkylsulfonyl
  • the water-soluble polymer (X) used in the present invention can be obtained by a conventional polymer synthesis method.
  • the methods and conditions for chain polymerization etc. are not particularly limited, and conventional methods and conditions can be appropriately applied depending on the purpose.
  • the "water solubility" of the water-soluble polymer (X) can be controlled, for example, by the types of constituent components and their contents.
  • the water-soluble polymer (X) may be used alone or in combination of two or more.
  • the water-soluble polymer (Y) is a water-soluble polymer having a different structure from the water-soluble polymer (X) described above, and is used as a thickener for a slurry for forming an electrode active material layer of a secondary battery.
  • a thickener for a slurry for forming an electrode active material layer of a secondary battery.
  • a wide variety of functional materials can be used.
  • the above-mentioned thickener include polysaccharides that function as thickeners, and may be either natural polysaccharides or synthetic polysaccharides, and examples include the following.
  • cellulose compounds that are polysaccharide thickeners include methylcellulose, ethylcellulose, benzylcellulose, triethylcellulose, cyanoethylcellulose, nitrocellulose, hydroxymethylcellulose, hydroxyethylcellulose (HEC), hydroxypropylcellulose (HPC), and hydroxypropylmethylcellulose (HPMC). , hydroxybutylmethylcellulose, carboxymethylcellulose (CMC), aminomethylhydroxypropylcellulose, aminoethylhydroxypropylcellulose, cellulose nanofiber (CNF), cellulose nanocrystal (CNC), and the like.
  • the cellulose compound may be in the form of a salt such as an ammonium salt, a sodium salt, or a lithium salt.
  • the degree of ether substitution may normally be from 0.5 to 1.5, preferably from 0.5 to 1.0.
  • the degree of ether substitution means the average number of hydroxyl groups substituted with ether groups per glucose ring unit of cellulose, and can be measured by titration or the like.
  • natural polysaccharides other than the cellulose compounds include carrageenan, xanthan gum, guar gum, tamarind gum (tamarind seed gum), diutan gum, welan gum, gellan gum, locust bean gum, and tara gum.
  • the water-soluble polymer (Y) may include at least one of carboxymethylcellulose (CMC), hydroxyethylcellulose (HEC), hydroxypropylcellulose (HPC), hydroxypropylmethylcellulose (HPMC), carrageenan, and xanthan gum.
  • CMC carboxymethylcellulose
  • HEC hydroxyethylcellulose
  • HPMC hydroxypropylmethylcellulose
  • carrageenan hydroxypropylmethylcellulose
  • xanthan gum xanthan gum.
  • carboxymethylcellulose CMC
  • HEC hydroxyethylcellulose
  • HPMC hydroxypropylmethylcellulose
  • carrageenan hydroxypropylmethylcellulose
  • xanthan gum xanthan gum
  • the weight average molecular weight (Mw) of the water-soluble polymer (Y) used in the present invention is not particularly limited, and is preferably, for example, 100,000 to 500,000, more preferably 150,000 to 500,000, and even more preferably 200,000 to 500,000.
  • the weight average molecular weight of the water-soluble polymer (Y) is a value measured by the method described in the above-mentioned water-soluble polymer (X).
  • the water-soluble polymer (Y) may be used alone or in combination of two or more.
  • the binder composition of the present invention contains polymer particles from the viewpoint of further improving cycle characteristics.
  • the polymer particles that may be contained are particulate polymers, and "particulate” may be flat, amorphous, etc., and preferably spherical or granular.
  • the polymer particles are particles of a water-insoluble polymer. That is, the polymer particles are particles of a polymer whose solubility in water at 20° C. is less than 10 g/L-H 2 O (not more than 10 g per liter of water).
  • the tensile modulus of the polymer particles is preferably 100 to 3000 MPa, more preferably 100 to 1000 MPa, from the viewpoint of improving cycle characteristics.
  • the above tensile modulus is calculated in the same manner as in the method for calculating the tensile modulus of a binder composition described in Examples below, except that a test piece is prepared using an aqueous solution of polymer particles instead of the binder composition. It can be determined by
  • the glass transition temperature of the polymer particles is not particularly limited, and from the viewpoint of improving the adhesion and cycle characteristics of the electrode sheet, it is preferably -50 to 150 °C, more preferably -30 to 100 °C, and even more preferably 0 to 100 °C. .
  • a polymer particle has two or more glass transition temperatures, it is preferable that all of them fall within the above-mentioned preferable range.
  • the glass transition temperature of the polymer particles is the value listed in the manufacturer's catalog.
  • the manufacturer's glass transition temperature information is not available or when using synthesized polymer particles, the glass transition temperature values in the table in Chapter 36 of the literature POLYMER HANDBOOK 4th are adopted.
  • the value of the glass transition temperature obtained by measurement under the following measurement conditions is adopted.
  • the glass transition temperature (Tg) is calculated by measuring a dry sample of polymer particles using a differential scanning calorimeter: X-DSC7000 (trade name, manufactured by SII Nano Technology Co., Ltd.) under the following measurement conditions. Measurements are performed twice on the same sample, and the results of the second measurement are used.
  • Tg is calculated by rounding off the decimal point of the intermediate temperature between the start point and end point of the drop on the DSC (differential scanning calorimetry) chart.
  • the average particle diameter (volume-based median diameter in water) of the polymer particles is not particularly limited, and is preferably from 50 to 300 nm, more preferably from 50 to 250 nm, even more preferably from 50 to 200 nm.
  • the average particle diameter of the polymer particles is the value listed in the manufacturer's catalog. If the manufacturer's average particle size information is not available or if synthesized polymer particles are used, the average particle size of the polymer particles is the cumulative volume calculated from the small diameter side in the particle size distribution measured by laser diffraction/scattering method. is the particle diameter (median diameter on a volume basis in water) at which 50% is obtained.
  • the polymer particles may be either sequential polymer particles or chain polymer particles, and chain polymer particles are preferred.
  • the chain polymer particles may be homopolymers or copolymers.
  • the polymerization form of the copolymer may be either random or block.
  • Constituent components of the polymer particles (chain polymerization polymer) include, for example, a conjugated diene component, an aromatic vinyl monomer component, an ethylenically unsaturated carboxylic acid component, a cyano group-containing ethylenic monomer component, and an ethylenically unsaturated carboxylic acid ester component.
  • the polymer particles have a conjugated diene component and an aromatic vinyl monomer component among the above components.
  • the aromatic vinyl monomer component means a component derived from a monomer having a carbon-carbon double bond (preferably one or two, more preferably one) and an aryl group (preferably one).
  • the ethylenically unsaturated carboxylic acid component means a component derived from a monomer having a carbon-carbon double bond (preferably one) and a carboxy group (preferably one or two), and contains a cyano group.
  • the ethylenic monomer component means a component derived from a monomer having a carbon-carbon double bond (preferably one) and a cyano group (preferably one or two, more preferably one);
  • the unsaturated carboxylic acid ester component means a component derived from a monomer having a carbon-carbon double bond (preferably one) and a carboxylic acid ester moiety (esterified carboxy group) (preferably one).
  • the fluorinated vinyl monomer component means an ethylene-derived component having 1 to 4 (preferably 2) fluorine atoms. Note that the above-mentioned "carbon-carbon double bond" does not include the carbon-carbon double bond of an aromatic ring.
  • conjugated diene leading to the conjugated diene component examples include 1,3-butadiene, 2-methyl-1,3-butadiene (isoprene), 2,3-dimethyl-1,3-butadiene, and 2-chloro-1,3 - Aliphatic conjugated dienes such as butadiene.
  • aromatic vinyl monomer leading to the aromatic vinyl monomer component examples include styrene, ⁇ -methylstyrene, 4-tert-butylstyrene, 4-tert-butoxystyrene, and vinyltoluene (3-vinyltoluene, 4-vinyltoluene).
  • Examples of the ethylenically unsaturated carboxylic acid leading to the ethylenically unsaturated carboxylic acid component include (meth)acrylic acid, maleic acid, itaconic acid, and fumaric acid.
  • Examples of the cyano group-containing ethylenic monomer leading to the cyano group-containing ethylenic monomer component include (meth)acrylonitrile, ⁇ -chloroacrylonitrile, ⁇ -ethyl acrylonitrile, and vinylidene cyanide.
  • Examples of the ethylenically unsaturated carboxylic ester that leads to the ethylenically unsaturated carboxylic ester component include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, Hexyl (meth)acrylate, octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, ethylene glycol di(meth)acrylate and 2,2,2-trifluoroethyl (meth)acrylate. ) (meth)acrylic acid alkyl esters such as acrylate.
  • Examples of the vinyl fluoride monomer leading to the vinyl fluoride monomer component include vinylidene fluoride.
  • the polymer particles used in the present invention can be obtained by conventional polymer synthesis methods.
  • the methods and conditions for chain polymerization etc. are not particularly limited, and conventional methods and conditions can be appropriately applied depending on the purpose.
  • the polymer particles may be particles obtained by performing a modification treatment such as carboxy modification on the above-mentioned sequential polymer particles and chain polymer particles.
  • the method and conditions for the modification treatment are not particularly limited, and can be carried out by conventional methods.
  • the water solubility, tensile modulus, glass transition temperature, and average particle size of the polymer particles can be adjusted, for example, by adjusting the types and contents of the constituent components in the polymer.
  • polymer particles include styrene/butadiene copolymers, acrylic polymers, and poly(vinylidene fluoride), with styrene/butadiene copolymers being preferred.
  • the styrene/butadiene copolymer means a copolymer having the above-mentioned aromatic vinyl monomer component and the above-mentioned conjugated diene component, and may be a modified copolymer such as a carboxy-modified copolymer.
  • the acrylic polymer means a polymer containing the ethylenically unsaturated carboxylic acid component and/or the ethylenically unsaturated carboxylic acid ester component.
  • Examples of the styrene/butadiene copolymer include WO 2021/172208, WO 2021/153516, WO 2021/065457, WO 2019/188722, WO 2018/173717, Publication No. 2017/056466, International Publication No. 2014/141721, JP 2014-203771, WO 2013/141140, JP 2014-116263, JP 2003-151560, JP 2000 -123838, JP 2000-100436, WO 1999/048953, WO 2020/226035, WO 2014/057749, JP 2019-179631, JP 2017-126456 No.
  • JP-A No. 2010-140684 can be used.
  • acrylic polymer examples include JP 2020-123590 A, WO 2018/173717, JP 2016-024985, WO 2015/107896, WO 2014/148064, and WO 2014/148064.
  • Examples of poly(vinylidene fluoride) include JP2014-229406A, WO2013/005796, WO2011/040474, WO2009/123168, and WO2014/057749.
  • the one described in International Publication No. 2012/117910 can be used.
  • those described in paragraph numbers 0120 to 0123 of International Publication No. 2013/005796 can be used.
  • one type of polymer particles may be used alone, or two or more types may be used in combination.
  • the binder composition of the present invention contains, in addition to the water-soluble polymer (X), the water-soluble polymer (Y), and the polymer particles that may be contained, other polymers commonly used as binders for batteries. May contain.
  • Water-soluble polymer (X) and water-soluble polymer (Y) account for the total of water-soluble polymer (X), water-soluble polymer (Y), and other polymers contained in the binder composition of the present invention
  • the total proportion is preferably 80% by mass or more, more preferably 90% by mass or more, even more preferably 95% by mass or more, particularly preferably 99% by mass or more, and most preferably 100% by mass.
  • the mass ratio of water-soluble polymer (X) to water-soluble polymer (Y) is particularly preferable.
  • 20-90:10-80 is preferable, and 40-80:20-60 is more preferable.
  • the binder composition of the present invention contains polymer particles, the water-soluble polymer (X), water-soluble polymer (Y), polymer particles and other polymers contained in the binder composition of the present invention
  • the proportion of the water-soluble polymer (X), the water-soluble polymer (Y), and the polymer particles in the total is preferably 80% by mass or more, more preferably 90% by mass or more, and even more preferably 95% by mass or more. It is preferably 99% by mass or more, particularly preferably 100% by mass.
  • the mass ratio of water-soluble polymer (X), water-soluble polymer (Y), and polymer particles is not particularly limited, and is preferably 10 to 80:10 to 80:10 to 50, more preferably 20 to 70:10 to 60:20 to 50.
  • the binder composition of the present invention preferably contains water as a liquid medium.
  • the content of water in the binder composition of the present invention is not particularly limited, and can be, for example, 10% by mass or more, preferably 20% by mass or more, more preferably 30% by mass or more, still more preferably 40% by mass or more. It can be at least 50% by mass, particularly preferably at least 50% by mass.
  • the binder composition of the present invention may contain water in an amount of 60% by mass or more, 70% by mass or more, or 80% by mass or more. On the other hand, it is practical for the content of water in the binder composition of the present invention to be 99.5% by mass or less.
  • the binder composition of the present invention may contain a liquid medium other than water.
  • liquid media other than water examples include organic solvents that mix with water without phase separation (hereinafter referred to as water-soluble organic solvents), such as N-methylpyrrolidone, methanol, ethanol, and acetone. , tetrahydrofuran, etc. are preferably mentioned.
  • water-soluble organic solvents such as N-methylpyrrolidone, methanol, ethanol, and acetone. , tetrahydrofuran, etc. are preferably mentioned.
  • the contents of the water-soluble polymer (X) and the water-soluble polymer (Y) may be appropriately set depending on the purpose.
  • the total content of water-soluble polymer (X) and water-soluble polymer (Y) in the binder composition can be 0.5 to 50% by mass, preferably 5 to 30% by mass, and more. Preferably it is 5 to 25% by mass.
  • the contents of the water-soluble polymer (X), the water-soluble polymer (Y), and the polymer particles that may be contained may be appropriately set depending on the purpose.
  • the total content of water-soluble polymer (X), water-soluble polymer (Y), and polymer particles in the binder composition can be 0.5 to 50% by mass, preferably 5 to 30% by mass. % by weight, more preferably 10-20% by weight.
  • the binder composition of the present invention can be used in addition to the water-soluble polymer (X), the water-soluble polymer (Y), the polymer particles that may be contained, water and a liquid medium other than water, depending on the purpose. It may contain other ingredients. Examples of other components include polyhydric alcohols (alcohols having two or more hydroxy groups).
  • the binder composition of the present invention can also be prepared by diluting each synthetic solution of the water-soluble polymer (X), the water-soluble polymer (Y), and the polymer particles that may be contained. Therefore, in the binder composition of the present invention, the water-soluble polymer (X) and the water-soluble polymer (Y), the compound used in the synthesis of the polymer particles that may be contained, or the by-products after the reaction. It may contain things.
  • the tensile modulus of the binder composition of the present invention is preferably 3,500 to 15,000 MPa, more preferably 4,500 to 12,000 MPa, even more preferably 6,000 to 10,000 MPa, when polymer particles are not included.
  • the pressure is preferably 1,500 to 6,000 MPa, more preferably 2,000 to 5,000 MPa, and even more preferably 2,500 to 5,000 MPa.
  • the tensile modulus can be determined by the method for calculating the tensile modulus of a binder composition described in Examples below.
  • the binder composition of the present invention in addition to the water-soluble polymer (X), the water-soluble polymer (Y), the polymer particles that may be contained, and water, It may contain an active material capable of inserting and releasing metal ions belonging to Group 1 or Group 2 in the table.
  • the case where the active material is contained in the binder composition of the present invention is particularly referred to as the electrode composition of the present invention.
  • the electrode composition of the present invention may further contain a conductive additive and other additives, if necessary.
  • the active material may be a positive electrode active material or a negative electrode active material.
  • the electrode composition when the electrode composition includes a positive electrode active material, the electrode composition can be used as a slurry for forming a positive electrode active material layer of a secondary battery. Moreover, when the electrode composition contains a negative electrode active material, the electrode composition can be used as a slurry for forming a negative electrode active material layer.
  • the binder composition of the present invention can be applied to either a positive electrode composition or a negative electrode composition, it is preferably used for a negative electrode, and is particularly preferably used for a negative electrode composition containing a silicon-based active material.
  • the above-mentioned active material, conductive aid, and other additives are not particularly limited, and may be appropriately selected from those commonly used in secondary batteries depending on the purpose.
  • the content of the water-soluble polymer (X) and the water-soluble polymer (Y) in the electrode composition of the present invention is not particularly limited, and is 0.5 to 30% by mass in total based on the total solid content. is preferable, 1.0 to 20% by weight is more preferable, still more preferably 1.5 to 15% by weight, and particularly preferably 2.5 to 10% by weight.
  • the mass ratio of water-soluble polymer (X) to water-soluble polymer (Y) is There is no particular restriction, but the ratio is preferably 20-90:10-80, more preferably 40-80:20-60.
  • the contents of the water-soluble polymer (X), the water-soluble polymer (Y), and the polymer particles in the electrode composition of the present invention are particularly Without limitation, the total amount is preferably 0.5 to 30% by mass, more preferably 1.0 to 20% by mass, even more preferably 1.5 to 15% by mass, and 2.5 to 10% by mass based on the total solid content. % by weight is particularly preferred.
  • the mass ratio of water-soluble polymer (X), water-soluble polymer (Y), and polymer particles is not particularly limited, and is preferably 10 to 80:10 to 80:10 to 50, more preferably 20 to 70:10 to 60:20 to 50.
  • the water content is preferably 30 to 70% by mass, more preferably 40 to 60% by mass, and even more preferably 45 to 55% by mass.
  • the electrode composition of the present invention contains water derived from the binder composition of the present invention, and further contains water added at the time of preparing the electrode composition. may contain water.
  • the solid content is preferably 30 to 70% by mass, more preferably 40 to 60% by mass, and even more preferably 45 to 55% by mass.
  • the proportion of the water-soluble polymer (X), the water-soluble polymer (Y), the polymer particles, the active material, and the conductive aid in the total solid content contained in the electrode composition of the present invention is The content is preferably 70% by mass or more, more preferably 80% by mass or more, even more preferably 90% by mass or more, and particularly preferably 95% by mass or more.
  • it is most preferable that all of the solid content contained in the electrode composition of the present invention is the water-soluble polymer (X), the water-soluble polymer (Y), the polymer particles, the active material, and the conductive additive. preferable.
  • the electrode composition of the present invention contains an active material capable of intercalating and ejecting metal ions belonging to Group 1 or Group 2 of the periodic table.
  • the positive electrode active material may be any active material that can insert and release metal ions belonging to Group 1 or Group 2 of the periodic table, and preferably one that can reversibly insert and release lithium ions.
  • the material is not particularly limited as long as it has the above characteristics, and may be a transition metal oxide, an organic substance, a compound having an element such as sulfur that can be complexed with Li, a composite of sulfur and a metal, or the like.
  • a transition metal oxide as the positive electrode active material, and a transition metal oxide containing a transition metal element M a (one or more elements selected from Co, Ni, Fe, Mn, Cu, and V) is preferable. more preferable.
  • this transition metal oxide contains elements M b (metal elements of group 1 (Ia) of the periodic table other than lithium, elements of group 2 (IIa) of the periodic table, Al, Ga, In, Ge, Sn, Pb, Elements such as Sb, Bi, Si, P, or B may be mixed.
  • the mixing amount of element M b is preferably 0 to 30 mol % with respect to 100 mol % of transition metal element M a . It is more preferable to synthesize Li by mixing the transition metal element M a with a molar ratio (Li/M a ) of 0.3 to 2.2.
  • transition metal oxides include (MA) transition metal oxides having a layered rock salt structure, (MB) transition metal oxides having a spinel structure, (MC) lithium-containing transition metal phosphate compounds, (MD ) Lithium-containing transition metal halide phosphoric acid compounds and (ME) lithium-containing transition metal silicate compounds.
  • transition metal oxides having a layered rock salt type structure include LiCoO 2 (lithium cobalt oxide [LCO]), LiNi 2 O 2 (lithium nickel oxide), LiNi 0.85 Co 0.10 Al 0. 05 O 2 (nickel cobalt lithium aluminate [NCA]), LiNi 1/3 Co 1/3 Mn 1/3 O 2 (nickel manganese cobalt lithium [NMC]), and LiNi 0.5 Mn 0.5 O 2 ( lithium manganese nickelate).
  • LiCoO 2 lithium cobalt oxide [LCO]
  • LiNi 2 O 2 lithium nickel oxide
  • LiNi 0.85 Co 0.10 Al 0. 05 O 2 nickel cobalt lithium aluminate [NCA]
  • LiNi 1/3 Co 1/3 Mn 1/3 O 2 nickel manganese cobalt lithium [NMC]
  • LiNi 0.5 Mn 0.5 O 2 lithium manganese nickelate
  • transition metal oxides having a spinel structure include LiMn 2 O 4 (LMO), LiCoMnO 4 , Li 2 FeMn 3 O 8 , Li 2 CuMn 3 O 8 , Li 2 CrMn 3 O 8 and Li 2NiMn3O8 is mentioned .
  • LMO LiMn 2 O 4
  • MC lithium-containing transition metal phosphate compounds
  • iron pyrophosphates such as LiFeP 2 O 7 , LiCoPO 4 , etc.
  • lithium-containing transition metal halide phosphate compounds include iron fluorophosphates such as Li 2 FePO 4 F, manganese fluorophosphates such as Li 2 MnPO 4 F, and Li 2 CoPO 4 F.
  • Examples include cobalt fluorophosphate salts such as.
  • ME Examples of the lithium-containing transition metal silicate compound include Li 2 FeSiO 4 , Li 2 MnSiO 4 and Li 2 CoSiO 4 .
  • (MA) transition metal oxides having a layered rock salt type structure are preferred, and LCO or NMC is more preferred.
  • the shape of the positive electrode active material is not particularly limited, and preferably particulate.
  • the average particle diameter (volume-based median diameter D50) of the positive electrode active material is not particularly limited. For example, it can be 0.1 to 50 ⁇ m.
  • it may be prepared by a conventional method using a pulverizer or a classifier. A method for preparing a negative electrode active material to a predetermined particle size, which will be described later, can also be applied.
  • the positive electrode active material obtained by the calcination method may be used after being washed with water, an acidic aqueous solution, an alkaline aqueous solution, an organic solvent, or the like.
  • the average particle diameter of the cathode active material is the value listed in the manufacturer's catalog. If information on the average particle size from the manufacturer is not available or when using a synthesized cathode active material, the average particle size of the cathode active material should be the value measured and calculated by the method described in the negative electrode active material section below. .
  • the chemical formula of the compound obtained by the above firing method can be calculated using inductively coupled plasma (ICP) emission spectrometry as a measurement method, or from the difference in mass of the powder before and after firing as a simple method.
  • ICP inductively coupled plasma
  • the surface of the positive electrode active material may be coated with another oxide such as a metal oxide, a carbon-based material, or the like.
  • a surface coating material that can be used for surface coating of a negative electrode active material, which will be described later, can be used.
  • the surface of the positive electrode active material may be surface-treated with sulfur or phosphorus.
  • the particle surface of the positive electrode active material may be surface-treated with active light or active gas (plasma, etc.) before and after the surface coating.
  • the above positive electrode active materials may be used alone or in combination of two or more.
  • the mass (mg) (basis weight) of the positive electrode active material per unit area (cm 2 ) of the positive electrode active material layer is not particularly limited. It can be determined as appropriate depending on the designed battery capacity.
  • the content of the positive electrode active material in the electrode composition of the present invention is not particularly limited, and is preferably 10 to 99% by mass, more preferably 30 to 98% by mass, and 50 to 97% by mass based on the total solid content. % is more preferable, and 55 to 95% by weight is particularly preferable.
  • the negative electrode active material may be any active material that can insert and release metal ions belonging to Group 1 or Group 2 of the periodic table, and preferably one that can reversibly insert (occlude) and release lithium ions. .
  • the material is not particularly limited as long as it has the above characteristics, such as carbonaceous materials, silicon-based materials (meaning materials containing the silicon element), tin-based materials (meaning the materials containing the tin element). ), metal oxides, metal composite oxides, simple lithium, lithium alloys, etc. Among these, carbonaceous materials or silicon-based materials are preferably used from the viewpoint of reliability.
  • the carbonaceous material used as the negative electrode active material is a material consisting essentially of carbon.
  • Examples include petroleum pitch, carbon black such as acetylene black, graphite (natural graphite such as flaky graphite and lumpy graphite, artificial graphite such as vapor-grown graphite and fibrous graphite, expanded graphite made by specially processing flaky graphite, etc.) ), activated carbon, carbon fiber, coke, soft carbon, hard carbon, and carbonaceous materials obtained by firing various synthetic resins such as PAN (polyacrylonitrile) resin or furfuryl alcohol resin.
  • PAN polyacrylonitrile
  • various carbon fibers such as PAN carbon fiber, cellulose carbon fiber, pitch carbon fiber, vapor grown carbon fiber, dehydrated PVA (polyvinyl alcohol) carbon fiber, lignin carbon fiber, glassy carbon fiber, and activated carbon fiber. Mention may also be made of mesophase microspheres, graphite whiskers, and tabular graphite.
  • the metal oxides and metal composite oxides used as negative electrode active materials are those that can intercalate and deintercalate (preferably intercalate and deintercalate) metal ions (preferably lithium ions) belonging to Group 1 or Group 2 of the periodic table.
  • metal oxides include oxides of metal elements (metal oxides) and oxides of metalloid elements (metalloid oxides)
  • metal composite oxides include Examples include composite oxides of metal elements, composite oxides of metal elements and metalloid elements, and composite oxides of metalloid elements.
  • amorphous oxides are preferred, and chalcogenides, which are reaction products of metal elements and elements of group 16 of the periodic table, are also preferred.
  • amorphous as used herein means that it has a broad scattering band with a peak in the 2 ⁇ value range of 20° to 40°, as determined by X-ray diffraction using CuK ⁇ rays, and the crystalline diffraction line It may have.
  • the compound group consisting of the above-mentioned amorphous oxides and chalcogenides the amorphous oxides of metalloid elements or the above-mentioned chalcogenides are more preferable, and elements of groups 13 (IIIB) to 15 (VB) of the periodic table are preferred.
  • oxides or composite oxides, or chalcogenides consisting of one of the following (for example, Al, Ga, Si, Sn, Ge, Pb, Sb, and Bi) or a combination of two or more thereof.
  • amorphous oxides and chalcogenides include, for example, Ga 2 O 3 , GeO, PbO, PbO 2 , Pb 2 O 3 , Pb 2 O 4 , Pb 3 O 4 , Sb 2 O 3 , Sb 2 O 4 , Sb2O8Bi2O3 , Sb2O8Si2O3 , Sb2O5 , Bi2O3 , Bi2O4 , GeS , PbS , PbS2 , Sb2S3 and Sb2S 5 is preferred.
  • the metal (composite) oxide and the chalcogenide preferably contain at least one of titanium and lithium as a constituent from the viewpoint of high current density charge/discharge characteristics.
  • the metal composite oxide containing lithium (lithium composite metal oxide) is, for example, a composite oxide of lithium oxide and the above metal (composite) oxide or the above chalcogenide, more specifically, Li 2 SnO 2 Can be mentioned.
  • the negative electrode active material contains titanium element. More specifically, TiNb 2 O 7 (niobium titanate oxide [NTO]) and Li 4 Ti 5 O 12 (lithium titanate [LTO]) have small volume fluctuations when lithium ions are absorbed and released, so they are suitable for rapid charging. It is preferable because it has excellent discharge characteristics, suppresses electrode deterioration, and makes it possible to improve the cycle characteristics of a lithium ion secondary battery.
  • NTO niobium titanate oxide
  • Li 4 Ti 5 O 12 lithium titanate [LTO]
  • the lithium alloy as a negative electrode active material is not particularly limited as long as it is an alloy commonly used as a negative electrode active material of secondary batteries, and examples thereof include lithium aluminum alloys.
  • the silicon-based material is a negative electrode active material containing the silicon element, such as silicon materials such as Si and SiOx (0 ⁇ x ⁇ 1.5), as well as titanium, vanadium, chromium, Silicon-containing alloys (e.g. LaSi 2 , VSi 2 ) containing manganese, nickel, copper or lanthanum, or structured active materials (e.g. LaSi 2 /Si), as well as the metal oxides and metal composite oxides mentioned above. Examples include oxides or composite oxides containing silicon elements in the description of products, and active materials containing silicon elements and tin elements such as SnSiO 3 and SnSiS 3 . SiOx itself can be used as a negative electrode active material (semi-metal oxide), and since Si is generated during battery operation, it can be used as an active material (its precursor material) that can form an alloy with lithium. Can be done.
  • the negative electrode active material is preferably a negative electrode active material that can form an alloy with lithium.
  • the negative electrode active material capable of forming an alloy with lithium is not particularly limited as long as it is commonly used as a negative electrode active material of secondary batteries. Examples of such active materials include negative electrode active materials containing the silicon element and/or tin element described above, and metals such as Al and In.
  • a silicon-based active material is preferable because it enables higher battery capacity, and a silicon-based active material in which the content of silicon element is 40 mol % or more of all constituent elements is more preferable.
  • negative electrodes containing negative electrode active materials that can be alloyed with lithium are different from negative electrodes made only of carbonaceous materials ( It can store more Li ions than graphite, carbon black, etc.). That is, the amount of Li ions stored per unit mass increases. Therefore, battery capacity (energy density) can be increased. As a result, there is an advantage that the battery operating time can be extended.
  • a negative electrode active material that can form an alloy with lithium such as a negative electrode active material containing a silicon element and/or a tin element, is also referred to as a high-capacity active material.
  • the surface of the negative electrode active material may be coated with an oxide such as another metal oxide, a carbon-based material, etc. (hereinafter, surface coating with a carbon-based material is referred to as "carbon-coated”).
  • an oxide such as another metal oxide, a carbon-based material, etc.
  • surface coating with a carbon-based material is referred to as "carbon-coated”).
  • the surface coating material include metal oxides containing Ti, Nb, Ta, W, Zr, Al, Si, or Li.
  • lithium niobate compounds include spinel titanate, tantalum oxides, niobium oxides, lithium niobate compounds, and more specifically, Li 4 Ti 5 O 12 , Li 2 Ti 2 O 5 , LiTaO 3 , LiNbO3 , LiAlO2 , Li2ZrO3 , Li2WO4 , Li2TiO3 , Li2B4O7 , Li3PO4 , Li2MoO4 , Li3BO3 , LiBO2 , Li2 Examples include CO 3 , Li 2 SiO 3 , SiO 2 , TiO 2 , ZrO 2 , Al 2 O 3 and B 2 O 3 . Further, carbon-based materials such as C, SiC, and carbon-doped silicon oxide can also be used as surface coating materials.
  • the surface of the negative electrode active material may be surface-treated with sulfur or phosphorus.
  • the particle surface of the negative electrode active material may be surface-treated with active light or active gas (plasma, etc.) before and after the surface coating.
  • the negative electrode active material may be doped with a metal element.
  • the metal element doped is preferably at least one of Li, Ni, and Ti, and preferably Li. is more preferable.
  • a silicon-based active material as the negative electrode active material, and silicon oxide (SiO x (0 ⁇ x ⁇ 1.5)) or carbon-coated silicon oxide (carbon-coated SiO x ( It is more preferable to use 0 ⁇ x ⁇ 1.5), and even more preferable to use carbon-coated silicon oxide.
  • the carbon-coated silicon oxide may be further doped with a metal element.
  • the content ratio of the carbon element in the carbon-coated silicon oxide is not particularly limited, and is preferably 0.5 to 5% by mass, more preferably 1 to 3% by mass. Commercially available silicon oxide or carbon-coated silicon oxide may be used.
  • silicon oxide or carbon-coated silicon oxide in the negative electrode active material is not particularly limited, and can be, for example, 10 to 90% by mass, preferably 10 to 50% by mass, and more preferably 15 to 40% by mass. preferable.
  • the negative electrode active material is silicon oxide or carbon-coated silicon oxide
  • the average particle size is preferably 5 to 20 ⁇ m.
  • it is also preferable to use a silicon-based material doped with a metal element as the negative electrode active material more preferably a silicon-based material doped with at least one of Li, Ni, and Ti. More preferred are silicon-based materials.
  • the silicon-based material to be doped with the metal element is preferably silicon oxide or carbon-coated silicon oxide.
  • Commercially available products may be used as the silicon oxide doped with a metal element and the silicon oxide doped with a metal element and coated with carbon.
  • doping silicon oxide or carbon-coated silicon oxide with a metal element with reference to JP 2022-121582, WO 14/188851, JP 2021-150077, etc.
  • it can also be prepared by doping silicon oxide with a metal element and, if necessary, further applying a carbon coat.
  • both doped with a metal element and carbon coated refers to a product that is doped with a metal element and then subjected to a carbon coat treatment, and a product that is doped with a metal element and then subjected to a carbon coat treatment; Used to include both elements doped.
  • the shape of the negative electrode active material is not particularly limited, but a particulate shape is preferable.
  • the average particle diameter (volume-based median diameter D50) of the negative electrode active material is preferably 0.1 to 60 ⁇ m.
  • a predetermined particle size can be prepared by a conventional method using a crusher or a classifier. For example, a mortar, a ball mill, a sand mill, a vibrating ball mill, a satellite ball mill, a planetary ball mill, a swirling jet mill, a sieve, etc. are preferably used.
  • Wet pulverization can also be carried out in the presence of water or an organic solvent such as methanol during pulverization. In order to obtain a desired particle size, it is preferable to perform classification.
  • the classification method is not particularly limited, and a sieve, a wind classifier, etc. can be used as desired. Both dry and wet classification can be used.
  • the average particle diameter of the negative electrode active material is the value stated in the manufacturer's catalog. If information on the average particle size from the manufacturer is not available or if a synthesized negative electrode active material is used, disperse the negative electrode active material in water and use a laser diffraction/scattering particle size distribution measuring device (for example, Particle LA manufactured by HORIBA). -960V2 (trade name)), the average particle diameter value (volume-based median diameter D50 in water) is adopted.
  • the negative electrode active material which is unstable in water, may be measured and calculated by other methods such as SEM (Scanning Electron Microscope) observation.
  • the negative electrode active materials may be used alone or in combination of two or more. Among these, a combination of a silicon-based active material and a carbonaceous material is preferred, a combination of a silicon-based active material and graphite is more preferred, and a combination of silicon oxide and/or carbon-coated silicon oxide and graphite is even more preferred.
  • the silicon oxide and carbon-coated silicon oxide may be silicon oxide doped with the above-mentioned metal element and silicon oxide doped with both the metal element and carbon coating, respectively.
  • the metal element to be doped is preferably at least one of Li, Ni, and Ti, and more preferably Li.
  • the mass ratio of the silicon-based active material to graphite is preferably 2 or less, more preferably 1 or less, and even more preferably 0.5 or less. Although there is no particular restriction on the lower limit of the mass ratio of silicon-based active material to graphite, 0.05 or more is practical.
  • the mass (mg) (basis weight) of the negative electrode active material per unit area (cm 2 ) of the negative electrode active material layer is not particularly limited. It can be determined as appropriate depending on the designed battery capacity.
  • the content of the negative electrode active material in the electrode composition of the present invention is not particularly limited, and is preferably 10 to 99% by mass, more preferably 30 to 98% by mass, based on the total solid content. More preferably 45 to 97% by weight, particularly preferably 55 to 95% by weight.
  • metal ions belonging to Group 1 or Group 2 of the periodic table generated in the secondary battery may be used in place of the negative electrode active material. Can be done.
  • a negative electrode active material layer can be formed by combining these ions with electrons and depositing them as metal.
  • the electrode composition of the present invention may also contain a conductive additive, and it is particularly preferable that a silicon-based active material as a negative electrode active material is used in combination with a conductive additive.
  • a conductive aid there are no particular limitations on the conductive aid, and those known as general conductive aids can be used.
  • electron conductive materials such as carbon black such as acetylene black, Ketjen black, and furnace black, amorphous carbon such as needle coke, carbon fibers such as vapor-grown carbon fiber or carbon nanotubes, graphene or fullerene, etc.
  • the material may be a carbonaceous material, metal powder such as copper or nickel, or metal fiber, or a conductive polymer such as polyaniline, polypyrrole, polythiophene, polyacetylene, or polyphenylene derivative.
  • a conductive additive such as polyaniline, polypyrrole, polythiophene, polyacetylene, or polyphenylene derivative.
  • the conductive aids may be used alone or in combination of two or more.
  • the content of the conductive aid in the electrode composition of the present invention is preferably 0.5 to 60% by mass, more preferably 1.0 to 50% by mass, and 1.5 to 50% by mass, based on the total solid content. 40% by weight is more preferable, and 2.5 to 35% by weight is particularly preferable.
  • the shape of the conductive aid is not particularly limited, but is preferably particulate.
  • the average particle size (median diameter D50 in terms of volume (volume basis) in water) of the conductive additive is not particularly limited, and is preferably, for example, 0.01 to 50 ⁇ m, more preferably 0.02 to 10.0 ⁇ m.
  • the average particle diameter of the conductive aid is the value listed in the manufacturer's catalog. If information on the average particle size from the manufacturer is not available or when using a synthesized conductive additive, the average particle size of the conductive additive should be the average particle diameter of the negative electrode active material described above (volume-based median diameter D50 in water). ) may be used.
  • the electrode composition of the present invention may optionally contain a lithium salt, an ionic liquid, a thickener, an antifoaming agent, a leveling agent, a dehydrating agent, an antioxidant, etc. as other components other than the above-mentioned components. Can be done.
  • a lithium salt an ionic liquid, a thickener, an antifoaming agent, a leveling agent, a dehydrating agent, an antioxidant, etc.
  • the binder composition for a secondary battery of the present invention comprises a water-soluble polymer (X) and a water-soluble polymer (Y), preferably further polymer particles and/or water, and optionally any other components.
  • a mixture preferably a slurry, can be prepared by mixing, for example, in various commonly used mixers.
  • an active material is mixed, and further a conductive aid, other additives, etc. are mixed as appropriate.
  • the mixing method is not particularly limited, and may be mixed all at once or sequentially. Further, a mixture obtained by mixing a plurality of components may be mixed with other components.
  • a binder composition (electrode composition) can also be obtained by further mixing.
  • the electrode sheet of the present invention has a layer (electrode active material layer, that is, a negative electrode active material layer or a positive electrode active material layer) formed using the electrode composition of the present invention.
  • the electrode sheet of the present invention may be an electrode sheet having an electrode active material layer formed using the electrode composition of the present invention, and the electrode active material layer may be formed on a base material such as a current collector. It may be a sheet that does not have a base material and is formed only of an electrode active material layer (a negative electrode active material layer or a positive electrode active material layer). This electrode sheet usually has a structure in which an electrode active material layer is laminated on a current collector.
  • the electrode sheet of the present invention may have other layers such as a protective layer such as a release sheet and a coating layer.
  • the electrode sheet of the present invention is a material constituting a negative electrode active material layer or a positive electrode active material layer of a secondary battery, or a laminate of a negative electrode current collector and a negative electrode active material layer (negative electrode layer), or a positive electrode current collector and a positive electrode. It can be suitably used as a laminate of active material layers (positive electrode layer).
  • the current collector constituting the electrode sheet of the present invention is an electron carrier and is usually in the form of a film sheet.
  • the current collector can be appropriately selected depending on the active material.
  • the constituent material of the positive electrode current collector include aluminum, aluminum alloy, stainless steel, nickel, and titanium, with aluminum or aluminum alloy being preferred.
  • examples of the positive electrode current collector include those obtained by treating the surface of aluminum or stainless steel with carbon, nickel, titanium, or silver to form a coating layer (thin film).
  • the constituent material of the negative electrode current collector include aluminum, copper, copper alloy, stainless steel, nickel, and titanium, with aluminum, copper, copper alloy, or stainless steel being preferred.
  • examples of the negative electrode current collector include those obtained by treating the surface of aluminum, copper, copper alloy, or stainless steel with carbon, nickel, titanium, or silver to form a coating layer (thin film).
  • the thickness of the positive electrode active material layer constituting the electrode sheet of the present invention is not particularly limited, and can be, for example, 5 to 500 ⁇ m, preferably 20 to 200 ⁇ m. Further, the thickness of the positive electrode current collector constituting the electrode sheet of the present invention is not particularly limited, and may be, for example, 10 to 100 ⁇ m, preferably 10 to 50 ⁇ m.
  • the thickness of the negative electrode active material layer constituting the electrode sheet of the present invention is not particularly limited, and can be, for example, 5 to 500 ⁇ m, preferably 20 to 200 ⁇ m. Further, the thickness of the negative electrode current collector constituting the electrode sheet of the present invention is not particularly limited, and can be, for example, 10 to 100 ⁇ m, preferably 10 to 50 ⁇ m.
  • the electrode sheet of the present invention can be obtained by forming an electrode active material layer using the electrode composition of the present invention.
  • the electrode sheet of the present invention can be manufactured by forming a film using the electrode composition of the present invention.
  • the electrode composition of the present invention is applied onto a current collector or the like as a base material (possibly via another layer) to form a coating film, and this is dried. , it is possible to obtain an electrode sheet having an active material layer (coated dry layer) on a base material.
  • the secondary battery of the present invention can be obtained by incorporating the electrode sheet obtained by the above method for manufacturing an electrode sheet into at least one of the electrodes (positive electrode and negative electrode) of the secondary battery.
  • the secondary battery of the present invention In the secondary battery of the present invention, at least one of the positive electrode active material layer and the negative electrode active material layer is a layer formed using the electrode composition of the present invention.
  • the secondary battery of the present invention will be explained using the form of a non-aqueous electrolyte secondary battery as an example, but the secondary battery of the present invention is not limited to a non-aqueous electrolyte secondary battery. It broadly encompasses everything.
  • a non-aqueous electrolyte secondary battery that is a preferred embodiment of the present invention has a configuration including a positive electrode, a negative electrode, and a separator disposed between the positive electrode and the negative electrode.
  • the positive electrode has a positive electrode current collector and a positive electrode active material layer in contact with the positive electrode current collector
  • the negative electrode has a negative electrode current collector and a negative electrode active material layer in contact with the negative electrode current collector.
  • at least one of the positive electrode active material layer and the negative electrode active material layer is formed using the electrode composition of the present invention.
  • nonaqueous electrolyte secondary battery of the present invention has only one of a positive electrode active material layer and a negative electrode active material layer
  • the electrode active material layer of the nonaqueous electrolyte secondary battery of the present invention has only one of a positive electrode active material layer and a negative electrode active material layer.
  • non-aqueous electrolyte secondary batteries formed using the electrode composition of the present invention are also included.
  • the non-aqueous electrolyte secondary battery of the present invention functions as a secondary battery by charging and discharging by filling a non-aqueous electrolyte between the positive electrode and the negative electrode.
  • FIG. 1 is a cross-sectional view schematically showing the laminated structure of a general non-aqueous electrolyte secondary battery 10, including an operating electrode when operating the battery.
  • the nonaqueous electrolyte secondary battery 10 has a laminated structure including a negative electrode current collector 1, a negative electrode active material layer 2, a separator 3, a positive electrode active material layer 4, and a positive electrode current collector 5 in this order when viewed from the negative electrode side. are doing.
  • the space between the negative electrode active material layer 2 and the positive electrode active material layer 4 is filled with a non-aqueous electrolyte (not shown) and separated by a separator 3.
  • the separator 3 has pores, and functions as a positive and negative electrode separation membrane that insulates between the positive and negative electrodes while allowing electrolyte and ions to pass through the pores during normal use of the battery.
  • a positive and negative electrode separation membrane that insulates between the positive and negative electrodes while allowing electrolyte and ions to pass through the pores during normal use of the battery.
  • a light bulb is used as the operating portion 6, and the light bulb is lit by discharge.
  • the negative electrode current collector 1 and the negative electrode active material layer 2 are collectively referred to as a negative electrode
  • the positive electrode active material layer 4 and the positive electrode current collector 5 are collectively referred to as a positive electrode.
  • the secondary battery of the present invention includes an electrolytic solution (aqueous electrolyte).
  • electrolytes such as liquid, non-aqueous electrolytes
  • solid electrolyte materials such as separators.
  • these materials and members those used in ordinary secondary batteries can be used as appropriate.
  • the method for producing the secondary battery of the present invention a normal method is followed except that at least one of the positive electrode active material layer and the negative electrode active material layer is formed using the electrode composition of the present invention. It can be adopted as appropriate.
  • the members and manufacturing methods normally used for these secondary batteries for example, JP2016-201308A, JP2005-108835A, JP2012-185938A, and International Publication No. 2020/067106. etc. can be referred to as appropriate.
  • a preferred form of the non-aqueous electrolyte will be explained in more detail.
  • the electrolyte used in the nonaqueous electrolyte is preferably a salt of a metal ion belonging to Group 1 or Group 2 of the periodic table.
  • the metal ion salt used is appropriately selected depending on the intended use of the non-aqueous electrolyte. Examples include lithium salts, potassium salts, sodium salts, calcium salts, magnesium salts, etc. When used in secondary batteries etc., lithium salts are preferred from the viewpoint of output.
  • a non-aqueous electrolyte is used as an electrolyte for a lithium ion secondary battery, a lithium salt may be selected as the metal ion salt.
  • the lithium salt lithium salts commonly used in electrolytes of electrolytes for lithium ion secondary batteries are preferable, and examples thereof include the following lithium salts.
  • Inorganic lithium salt Inorganic fluoride salts such as LiPF 6 , LiBF 4 , LiAsF 6 , LiSbF 6 , perhalates such as LiClO 4 , LiBrO 4 , LiIO 4 , inorganic chloride salts such as LiAlCl 4 etc
  • Oxalatoborate salt lithium bis(oxalato)borate, lithium difluorooxalatoborate, etc.
  • LiPF 6 , LiBF 4 , LiAsF 6 , LiSbF 6 , LiClO 4 , Li(R f1 SO 3 ), LiN(R f1 SO 2 ) 2 , LiN(FSO 2 ) 2 , or LiN(R f1 SO 2 )(R f2 SO 2 ) is preferable, and LiPF 6 , LiBF 4 , LiN(R f1 SO 2 ) 2 , LiN(FSO 2 ) 2 or LiN(R f1 SO 2 )(R f2 SO 2 ) is preferable. More preferred.
  • R f1 and R f2 each represent a perfluoroalkyl group, and preferably have 1 to 6 carbon atoms. Note that the electrolytes used in the non-aqueous electrolyte may be used alone or in any combination of two or more.
  • the salt concentration of the electrolyte (preferably ions of metals belonging to Group 1 or Group 2 of the periodic table or metal salts thereof) in the non-aqueous electrolyte is selected as appropriate depending on the purpose of use of the non-aqueous electrolyte, but generally is 10 to 50% by mass, preferably 15 to 30% by mass, based on the total mass of the nonaqueous electrolyte.
  • the molar concentration is preferably 0.5 to 1.5M. Note that when evaluating the concentration of ions, it may be calculated in terms of metal salts that are suitably applied.
  • Non-aqueous solvent The non-aqueous electrolyte contains a non-aqueous solvent.
  • aprotic organic solvents are preferred, and aprotic organic solvents having 2 to 10 carbon atoms are particularly preferred.
  • Such nonaqueous solvents include chain or cyclic carbonate compounds, lactone compounds, chain or cyclic ether compounds, ester compounds, nitrile compounds, amide compounds, oxazolidinone compounds, nitro compounds, chain or cyclic sulfones, or Examples include sulfoxide compounds and phosphate ester compounds. Note that compounds having an ether bond, a carbonyl bond, an ester bond, or a carbonate bond are preferred. These compounds may have a substituent, and examples of the substituent that may be included include substituents selected from the above-mentioned substituent group T.
  • nonaqueous solvent examples include ethylene carbonate, fluorinated ethylene carbonate, vinylene carbonate, propylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, ethylmethyl carbonate, methylpropyl carbonate, ⁇ -butyrolactone, ⁇ -valerolactone, 1, 2-dimethoxyethane, tetrahydrofuran, 2-methyltetrahydrofuran, tetrahydropyran, 1,3-dioxolane, 4-methyl-1,3-dioxolane, 1,3-dioxane, 1,4-dioxane, methyl acetate, ethyl acetate, propion Methyl acid, ethyl propionate, methyl butyrate, methyl isobutyrate, methyl trimethyl acetate, ethyl trimethyl acetate, acetonitrile, glutaronitrile, adiponitrile, me
  • ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, ethylmethyl carbonate, and ⁇ -butyrolactone is preferable, and high viscosity (high dielectric constant) solvents such as ethylene carbonate or propylene carbonate (for example, dielectric
  • high viscosity solvents such as ethylene carbonate or propylene carbonate (for example, dielectric
  • a low viscosity solvent for example, viscosity ⁇ 1 mPa ⁇ s
  • the dissociation property of the electrolyte salt and the mobility of ions are improved.
  • the nonaqueous solvent used in the present invention is not limited to these.
  • the secondary battery of the present invention can be used, for example, in a notebook computer, a pen input computer, a mobile computer, an e-book player, a mobile phone, a cordless phone, a pager, a handy terminal, a mobile fax machine, a mobile copier, a mobile printer, a headphone stereo, a video It can be installed in electronic devices such as movies, LCD TVs, handy cleaners, portable CDs, mini discs, electric shavers, transceivers, electronic notebooks, calculators, portable tape recorders, radios, backup power supplies, and memory cards.
  • electronic devices such as movies, LCD TVs, handy cleaners, portable CDs, mini discs, electric shavers, transceivers, electronic notebooks, calculators, portable tape recorders, radios, backup power supplies, and memory cards.
  • Solution A prepared above was added dropwise to the distilled water in the 1 L three-necked flask over 1 hour. After completion of the dropwise addition, stirring was continued at 75° C. for 3 hours. It was cooled to room temperature to obtain an aqueous solution of polyacrylamide (PAAm).
  • the solid content concentration of the obtained aqueous solution was 14.0% by mass, the weight average molecular weight (Mw) of the obtained polyacrylamide was 360000, and the molecular weight distribution (Mw/Mn) was 2.40.
  • the monomer composition is changed as shown in Table 1 or 2 below, and/or the polymerization initiator is changed so that Mw and Mw/Mn are the values shown in Table 1 or 2 below.
  • the water-soluble polymers (X) shown in Table 1 or 2 were synthesized in the same manner as in the synthesis of the polyacrylamide above, except that the blending amount was adjusted.
  • the solid content concentration of the aqueous solutions of water-soluble polymers (X) prepared above was 14.0% by mass.
  • the water solubility of the water-soluble polymer (X) obtained above at 20°C was all 100 g/L-H 2 O or more.
  • the weight average molecular weight (Mw) and number average molecular weight (Mn) of the water-soluble polymer (X) were measured as described above.
  • a binder composition containing the water-soluble polymer (X) and water-soluble polymer (Y) listed in Table 1 was prepared as follows. In a 60 mL ointment container (manufactured by Umano Kagaku Co., Ltd.), add 7.50 g of an aqueous solution of water-soluble polymer (X) (solid content 1.05 g) and 8.00 g of an aqueous solution of water-soluble polymer (Y) (solid content 0.40 g). ) and stirred for 4 minutes at 2000 rpm using Awatori Rentaro (trade name, manufactured by THINKY) to obtain a binder composition. The solid content concentration of the binder composition was 9.35% by mass.
  • a binder composition containing the water-soluble polymer (X), water-soluble polymer (Y), and polymer particles listed in Table 2 was prepared as follows. In a 60 mL ointment container (manufactured by Umano Kagaku Co., Ltd.), add 7.50 g of an aqueous solution of water-soluble polymer (X) (solid content 1.05 g) and 8.00 g of an aqueous solution of water-soluble polymer (Y) (solid content 0.40 g). ) was added and dispersed for 4 minutes at 2000 rpm using Awatori Rentaro (trade name, manufactured by THINKY).
  • the binder composition prepared above was subjected to a tensile test as follows, and the tensile modulus was calculated. The results obtained are summarized in Tables 1 and 2.
  • the binder composition prepared above was applied to a peelable polyethylene terephthalate (PET) film (5 cm long, 0.5 cm wide, 0.1 mm thick) and dried.
  • PET polyethylene terephthalate
  • the coating film of the binder composition was peeled off from the PET film to obtain a test piece of the coating film of the binder composition measuring 5 cm in length, 0.5 cm in width, and 0.100 to 0.150 mm in thickness.
  • a negative electrode composition containing the water-soluble polymer (X) and water-soluble polymer (Y) listed in Table 1 was prepared as follows.
  • a 60 mL ointment container manufactured by Umano Chemical Co., Ltd.
  • a 60 mL ointment container was filled with 1.78 g of carbon-coated silicon oxide (carbon element content: 1.3% by mass, average particle size: 5 ⁇ m, manufactured by Osaka Titanium Co., Ltd.) and graphite ( 7.12 g of acetylene black (product name: MAG-D, manufactured by Showa Denko Materials), 0.60 g of acetylene black (product name: Denka Black, manufactured by Denka), and 2 g of an aqueous solution of water-soluble polymer (X).
  • a composition for a negative electrode was obtained by adding 0.69 g of distilled water to the dispersed liquid and dispersing it for 12 minutes at 2000 rpm using a foamer.
  • the solid content concentration of the negative electrode composition was 53% by mass.
  • a negative electrode composition containing the water-soluble polymer (X), water-soluble polymer (Y), and polymer particles listed in Table 2 was prepared as follows.
  • a 60 mL ointment container manufactured by Umano Chemical Co., Ltd.
  • carbon-coated silicon oxide carbon element content: 1.3% by mass, average particle size: 5 ⁇ m, manufactured by Osaka Titanium Co., Ltd.
  • graphite 7.12 g of acetylene black (product name: MAG-D, manufactured by Showa Denko Materials), 0.60 g of acetylene black (product name: Denka Black, manufactured by Denka), and 1 aqueous solution of water-soluble polymer (X).
  • the discharge capacity retention rate was measured as follows, and the cycle characteristics were evaluated. The results obtained are summarized in Tables 1 and 2.
  • Lithium foil (thickness 50 ⁇ m, 14.5 mm ⁇ ) and polypropylene separator (thickness 25 ⁇ m, 16.0 mm ⁇ ) were stacked in this order, and LiPF 6 ethylene carbonate/ethyl methyl carbonate (volume ratio 1:2) electrolyte solution (concentration 1M) was layered. 200 ⁇ L was soaked into the separator. Further, 200 ⁇ L of the above electrolyte solution was soaked onto the separator, and a disk-shaped negative electrode sheet was stacked so that the negative electrode active material layer surface was in contact with the separator. Thereafter, the 2032 type coin case was caulked to produce a nonaqueous electrolyte secondary battery (a battery having a laminate consisting of Li foil, separator, negative electrode active material layer, and copper foil).
  • a nonaqueous electrolyte secondary battery a battery having a laminate consisting of Li foil, separator, negative electrode active material layer, and copper foil.
  • the discharge capacity retention rate of each secondary battery produced as described above was measured using a charge/discharge evaluation device: TOSCAT-3000 (trade name, manufactured by Toyo System Co., Ltd.). Charging was carried out at a C rate (capacity rate) of 0.2 C (a rate at which the battery was fully charged in 5 hours) until the battery voltage reached 0.02 V. Discharging was performed at a C rate of 0.2C until the battery voltage reached 1.5V.
  • the secondary battery was initialized by repeating three cycles of charging and discharging, with one charging and one discharging as one charging/discharging cycle. The secondary battery after initialization was charged at 0.5C until reaching 0.02V, and discharged at 0.5C until it reached 1.5V.
  • the cycle characteristics were evaluated by repeating 80 cycles of charging and discharging, with one charging and one discharging being defined as one charging/discharging cycle.
  • discharge capacity at the first cycle after initialization initial discharge capacity
  • discharge capacity retention rate after 80 cycles of charging and discharging discharge capacity after 80 cycles of charging and discharging against [initial discharge capacity]
  • the cycle characteristics were evaluated by calculating the ratio) and applying it to the evaluation rank below. Note that both charging and discharging were performed at 25°C.
  • CMC Carboxymethyl cellulose (manufactured by Daicel Millize)
  • HEC Hydroxyethylcellulose (manufactured by Daicel Millize)
  • HPC Hydroxypropylcellulose (manufactured by Nippon Soda Co., Ltd.)
  • HPMC Hydroxypropyl methylcellulose (manufactured by Shin-Etsu Chemical Co., Ltd.)
  • Carrageenan Manufactured by Sansho Co., Ltd.
  • Xanthan gum Manufactured by Sansho Co., Ltd.
  • Mw Weight average molecular weight of water-soluble polymer (Y), 3 significant figures Y/X: Water solubility with respect to weight average molecular weight (Mw) of water-soluble polymer (X) Ratio of weight average molecular weight (Mw) of polymer (Y), 3 significant figures (polymer particles)
  • Polymer particles 1 Synthesized according to the production example of copolymer latex 1 described in paragraph number 0038 of JP-A-2012-212537.
  • Polymer particles 2 Synthesized according to the synthesis example of copolymer latex (B-2) described in paragraph number 0044 of JP-A-2011-171181.
  • Polymer particles 3 Synthesized according to the preparation example of polymer (A) described in paragraph number 0134 of International Publication No. 2020/226035.
  • Polymer particles 4 Synthesized according to the preparation example of particulate polymer Z1 described in paragraph number 0141 of JP-A-2020-123590. Note that all of the polymer particles 1 to 4 had a solubility in water of less than 10 g/L-H 2 O at 20°C. "Unmeasurable" in the tensile modulus column of Comparative Example 8 means that the binder composition was too brittle to prepare a test piece for measurement, and the tensile modulus could not be measured.
  • the ratio (Y/X) of the weight average molecular weight of the water-soluble polymer (Y) to the weight average molecular weight of the water-soluble polymer (X) is defined by the present invention. None of them are electrode compositions of the present invention in that they are outside the range. Further, the negative electrode composition of Comparative Example 7 does not contain the water-soluble polymer (Y), the negative electrode composition of Comparative Example 8 does not contain the water-soluble polymer (X), and the negative electrode composition of Comparative Example 9 and 10 does not contain the water-soluble polymer (X).
  • the negative electrode compositions meet the requirements of the present invention in that the water-soluble polymer described in the column of water-soluble polymer (X) contains only 10% by mass of the component represented by general formula (B-2). It is not a composition for electrodes.
  • the tensile modulus of the binder compositions used in the negative electrode compositions of these Comparative Examples 1 to 21 were all small, and the negative electrode sheets produced using the negative electrode compositions of these Comparative Examples 1 to 21 were All secondary batteries had poor cycle characteristics.
  • the negative electrode compositions of Examples 1 to 74 are all electrode compositions of the present invention.
  • the tensile moduli of the binder compositions used in the negative electrode compositions of Examples 1 to 74 were all large, and the secondary It was found that all the batteries exhibited excellent cycling characteristics.
  • the negative electrode active material was a metal dope prepared from carbon-coated silicon oxide (carbon element content: 1.3% by mass, average particle size: 5 ⁇ m, manufactured by Osaka Titanium Co., Ltd.) as follows.
  • a negative electrode composition was prepared in the same manner as in [Preparation Example 1 of Negative Electrode Composition] described above, except that the active material was changed.
  • the negative electrode active material was a metal dope prepared from carbon-coated silicon oxide (carbon element content: 1.3% by mass, average particle size: 5 ⁇ m, manufactured by Osaka Titanium Co., Ltd.) as follows.
  • a negative electrode composition was prepared in the same manner as in [Preparation Example 2 of Negative Electrode Composition] above, except that the active material was changed.
  • negative electrode composition a containing both lithium-doped and carbon-coated silicon oxide (LiSiOC), nickel-doped and Negative electrode composition b containing silicon oxide (NiSiOC) coated with both carbon and negative electrode composition c containing silicon oxide (TiSiOC) coated with both titanium and carbon.
  • LiSiOC lithium-doped and carbon-coated silicon oxide
  • Negative electrode composition b containing silicon oxide (NiSiOC) coated with both carbon
  • negative electrode composition c containing silicon oxide (TiSiOC) coated with both titanium and carbon
  • a silicon oxide (LiSiOC) was prepared. Specifically, it was performed as follows. A raw material (vaporized starting material) that is a mixture of metallic silicon and silicon dioxide is placed in a reactor, and the vaporized material is deposited on an adsorption plate in a vacuum atmosphere of 10 Pa. After cooling sufficiently, the deposit ( Silicon oxide) was taken out and ground in a ball mill. After adjusting the particle size, a carbon coat was formed by thermal CVD (thermal chemical vapor deposition).
  • pulverized silicon oxide was placed in a silicon nitride tray, and then placed in a processing furnace capable of maintaining an atmosphere.
  • argon gas was introduced to replace the inside of the processing furnace with argon, and then the temperature was raised at a rate of 300°C/hr while a methane-argon mixed gas was introduced at a rate of 2NL/min until the temperature reached 600 to 1,100°C.
  • thermal CVD was performed by holding the sample for 3 to 10 hours to obtain carbon-coated silicon oxide (SiOC). After the holding was completed, the temperature started to decrease, and after reaching room temperature, the powder was collected. Subsequently, the carbon-coated silicon oxide was doped with lithium by a redox method to perform modification.
  • solution A in which lithium pieces and naphthalene were dissolved in tetrahydrofuran (hereinafter referred to as THF).
  • this solution A is prepared by dissolving naphthalene in a THF solvent at a concentration of 0.2 mol/L, and then dissolving lithium pieces in a mass amount of 10% by mass with respect to the mixed solution of the THF solvent and naphthalene. It was created by adding. Further, the temperature of solution A when immersing the carbon-coated silicon oxide was 20° C., and the immersion time was 20 hours. Thereafter, the solid content was collected by filtration. Through the above treatment, the carbon-coated silicon oxide was doped with lithium.
  • the obtained solid content was heat treated at 600° C. for 24 hours in an argon atmosphere to stabilize the Li compound.
  • the carbon-coated silicon oxide was modified to obtain silicon oxide (LiSiOC) that was both lithium-doped and carbon-coated.
  • the content ratio of carbon element was 3% by mass, and the average particle size (volume-based median diameter D50) of the LiSiOC particles was 6.7 ⁇ m.
  • a powdered Si alloy was produced from the obtained molten alloy by a gas atomization method.
  • the atmosphere during the preparation of the molten alloy and during gas atomization was an argon atmosphere.
  • high-pressure (4 MPa) argon gas was sprayed onto the molten alloy falling in a rod shape inside the spray chamber.
  • the obtained powder was classified to 25 ⁇ m or less using a sieve and used as a Si alloy in subsequent steps.
  • (ii) Preparation for mechanical milling process Place a metal ball (size: ⁇ 3/8 inch, material: SUJ2 (high carbon chromium bearing steel SUJ2 according to JIS (Japanese Industrial Standards) G 4805 (2019)) in a stainless steel pot.
  • Si alloy and SiO 2 powder as a metal oxide were added at a mixing ratio shown in Table A below.
  • Table A For example, when producing 10 g of a target object, 9.5 g of Si alloy and 0.5 g of SiO 2 powder were charged. After charging, the atmosphere inside the pot was replaced with Ar gas.
  • a doped silicon-based material nickel-doped silicon oxide (NiSiO) or titanium-doped silicon oxide (TiSiO) was used.
  • Carbon coating treatment on a silicon-based material doped with a metal element A carbon coat was formed on a silicon-based material (NiSiO or TiSiO) doped with a metal element by performing thermal CVD.
  • the silicon-based material doped with a metal element after mechanical milling was placed in a silicon nitride tray, and then placed in a processing furnace capable of maintaining an atmosphere.
  • argon gas was introduced to replace the inside of the processing furnace with argon, and then the temperature was raised at a rate of 300°C/hr while a methane-argon mixed gas was introduced at a rate of 2NL/min until the temperature reached 600 to 1,100°C.
  • the carbon film is thermally CVDed by holding it for 3 to 10 hours to form a silicon-based material doped with a metal element and coated with carbon (silicon oxide (NiSiOC) coated with both nickel dope and carbon). ) and both titanium-doped and carbon-coated silicon oxide (TiSiOC)) were obtained. After the holding was completed, the temperature started to decrease, and after reaching room temperature, the powder was collected. Note that the content ratio of carbon element was 3% by mass, and the average particle diameter (volume-based median diameter D50) of both NiSiOC particles and TiSiOC particles was 7 ⁇ m.
  • NiSiO Nickel-doped silicon oxide
  • TiSiO Titanium-doped silicon oxide alloy
  • Composition Total of 100% by mass of Si alloy and SiO 2 powder input when obtaining a silicon-based material doped with a metal element (NiSiO or TiSiO) It shows the proportion of each metal element in the Si alloy, the unit is mass %, and the total alloy composition is 95 mass %.
  • the mixing ratio refers to the proportion of each component (Si alloy or SiO 2 powder) in the total amount of Si alloy and SiO 2 powder that are input when obtaining a silicon-based material doped with a metal element (NiSiO or TiSiO). The unit is mass %.
  • Nonaqueous electrolyte secondary battery 1 Negative electrode current collector 2 Negative electrode active material layer 3 Separator 4 Positive electrode active material layer 5 Positive electrode current collector 6 Operating part (light bulb)

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Abstract

The present invention provides: a binder composition for a secondary battery, the binder composition containing a water-soluble polymer (X) and a water-soluble polymer (Y), wherein the water-soluble polymer (X) is a polymer containing 20% by mass or more of a constituent having a specific structure represented by general formula (B-2), and the ratio of the weight-average molecular weight of the water-soluble polymer (Y) to the weight-average molecular weight of the water-soluble polymer (X) is 0.300-10.0; an electrode sheet and a secondary battery; and a method for producing the electrode sheet and the secondary battery.

Description

二次電池用バインダー組成物、電極シート及び二次電池、並びに、これら電極シート及び二次電池の製造方法Binder composition for secondary batteries, electrode sheets and secondary batteries, and methods for producing these electrode sheets and secondary batteries
　本発明は、二次電池用バインダー組成物、電極シート及び二次電池、並びに、これら電極シート及び二次電池の製造方法に関する。 The present invention relates to a binder composition for a secondary battery, an electrode sheet, a secondary battery, and a method for manufacturing these electrode sheets and secondary batteries.
　リチウムイオン二次電池に代表される二次電池は、パソコン、ビデオカメラ、携帯電話等のポータブル電子機器の動力源として用いられている。最近では、二酸化炭素排出量削減という地球規模の環境課題を背景に、自動車等の輸送機器の動力電源として、また、夜間電力、自然エネルギー発電による電力等の蓄電用途としても普及してきている。 Secondary batteries, typified by lithium ion secondary batteries, are used as a power source for portable electronic devices such as personal computers, video cameras, and mobile phones. Recently, against the backdrop of the global environmental challenge of reducing carbon dioxide emissions, they have become popular as a power source for transportation equipment such as automobiles, and as a storage device for nighttime electricity, electricity generated from natural energy, etc.
　リチウムイオン二次電池の電極（正極及び負極）は電極活物質層（正極活物質層及び負極活物質層）を有し、この電極活物質層は、充放電時にリチウムイオンを吸蔵ないし放出可能な電極活物質粒子を含み、また、必要により導電助剤等を含む。電極活物質、導電助剤等はいわゆる固体粒子であり、リチウムイオン二次電池の充放電（リチウムイオンの吸蔵放出）に伴う電極活物質粒子の膨張収縮により、固体粒子間の導通状態は損なわれやすい。導通状態が損なわれれば電池の内部抵抗が増大して電池容量が低下する。リチウムイオン二次電池のサイクル特性を向上させる（サイクル寿命を長期化する）には、充放電を繰り返しても固体粒子間の密着状態を維持できることが重要であり、電極活物質層は通常、バインダーを含む。
　例えば、特許文献１には、粒子状重合体及び水溶性重合体を含むリチウムイオン二次電池電極用バインダー組成物が記載されている。特許文献１には、この組成物を構成する水溶性重合体が、エチレン性不飽和カルボン酸単量体単位と、（メタ）アクリルアミド、Ｎ－２－ジメチルアミノエチル（メタ）アクリルアミド、及び、Ｎ－３－ジメチルアミノプロピル（メタ）アクリルアミドから選ばれる一種以上のカルボン酸アミド単量体単位と、上記カルボン酸アミド単量体単位以外の架橋性単量体単位とを、それぞれ特定の割合で含むこと；この組成物と、電極活物質と、カルボキシメチルセルロース塩とを組み合わせて、リチウムイオン二次電池の電極形成に適用することによって、得られるリチウムイオン二次電池中においてガスの発生を抑制し、リチウムイオン二次電池のサイクル特性が向上することが記載されている。 The electrodes (positive electrode and negative electrode) of a lithium ion secondary battery have electrode active material layers (positive electrode active material layer and negative electrode active material layer), and this electrode active material layer is capable of intercalating and releasing lithium ions during charging and discharging. Contains electrode active material particles and, if necessary, a conductive aid. Electrode active materials, conductive aids, etc. are so-called solid particles, and due to expansion and contraction of electrode active material particles associated with charging and discharging (intercalation and release of lithium ions) of a lithium ion secondary battery, the conductivity between solid particles is impaired. Cheap. If the conduction state is impaired, the internal resistance of the battery increases and the battery capacity decreases. In order to improve the cycle characteristics of lithium-ion secondary batteries (lengthen the cycle life), it is important to be able to maintain the adhesion state between solid particles even after repeated charging and discharging, and the electrode active material layer is usually made of a binder. including.
For example, Patent Document 1 describes a binder composition for a lithium ion secondary battery electrode that includes a particulate polymer and a water-soluble polymer. Patent Document 1 discloses that the water-soluble polymer constituting this composition comprises an ethylenically unsaturated carboxylic acid monomer unit, (meth)acrylamide, N-2-dimethylaminoethyl (meth)acrylamide, and N-2-dimethylaminoethyl (meth)acrylamide. Contains one or more carboxylic acid amide monomer units selected from -3-dimethylaminopropyl (meth)acrylamide and crosslinkable monomer units other than the above-mentioned carboxylic acid amide monomer units, each in a specific ratio. By applying this composition, an electrode active material, and a carboxymethylcellulose salt in combination to forming an electrode of a lithium ion secondary battery, gas generation is suppressed in the resulting lithium ion secondary battery, It is described that the cycle characteristics of lithium ion secondary batteries are improved.
国際公開第２０１４／１９６５４７号International Publication No. 2014/196547
　近年、二次電池の用途の拡大に伴い、二次電池には高エネルギー密度化及びサイクル特性の更なる向上が求められている。リチウムイオン二次電池の更なる高容量化を実現するために、負極活物質としてケイ素系活物質を用いる検討が盛んに行われている。負極にケイ素系活物質を用いると高エネルギー密度化が可能となる。しかし、ケイ素系活物質は充電時にリチウムイオンを多量に吸蔵して大きく膨張するため、その分、放電時におけるケイ素系活物質の収縮幅も大きくなる。したがって、負極活物質としてケイ素系活物質を用いたリチウムイオン二次電池は、充放電時の負極活物質の体積変化が大きく、電極活物質、導電助剤等のいわゆる固体粒子間の導通状態（密着状態）が損なわれやすいため、充放電の繰り返しにより電池性能が低下しやすい。つまり、サイクル特性の向上には制約がある。
　本発明者らが検討を進めたところ、上記特許文献１に記載されたバインダーをはじめ従来の電極用バインダーを用いた場合、得られる二次電池、特に、充放電に伴う体積変化の大きいケイ素系活物質を負極活物質として用いた二次電池のサイクル特性は十分とはいえないことがわかってきた。 In recent years, as the uses of secondary batteries have expanded, secondary batteries are required to have higher energy density and further improved cycle characteristics. In order to further increase the capacity of lithium ion secondary batteries, studies are actively underway to use silicon-based active materials as negative electrode active materials. When a silicon-based active material is used for the negative electrode, it becomes possible to increase the energy density. However, since the silicon-based active material absorbs a large amount of lithium ions and expands greatly during charging, the width of contraction of the silicon-based active material during discharging increases accordingly. Therefore, in a lithium ion secondary battery using a silicon-based active material as the negative electrode active material, the volume of the negative electrode active material changes greatly during charging and discharging, and the electrical conductivity between so-called solid particles such as the electrode active material and the conductive agent ( Since the adhesion state is likely to be impaired, battery performance is likely to deteriorate due to repeated charging and discharging. In other words, there are restrictions on improving cycle characteristics.
The present inventors have conducted studies and found that when conventional electrode binders such as the binder described in Patent Document 1 are used, the resulting secondary batteries, especially silicon-based batteries that have a large volumetric change during charging and discharging. It has been found that the cycle characteristics of secondary batteries using active materials as negative electrode active materials are not sufficient.
　本発明は、充放電時の体積変化の大きな電極活物質を用いた場合でも、得られる二次電池のサイクル特性を十分に高める（サイクル寿命を十分に長期化する）ことができる二次電池用バインダー組成物を提供することを課題とする。
　更に、本発明は、上記二次電池用バインダー組成物を用いた電極シート及び二次電池を提供することを課題とする。更に、本発明は、上記電極シート及び二次電池の製造方法を提供することを課題とする。 The present invention provides a secondary battery that can sufficiently improve the cycle characteristics (sufficiently extend the cycle life) of the obtained secondary battery even when using an electrode active material that exhibits a large volume change during charging and discharging. An object of the present invention is to provide a binder composition.
Furthermore, an object of the present invention is to provide an electrode sheet and a secondary battery using the binder composition for a secondary battery. Furthermore, it is an object of the present invention to provide a method for manufacturing the above electrode sheet and secondary battery.
　すなわち、本発明の上記課題は以下の手段により解決された。
＜１＞
　水溶性高分子（Ｘ）及び水溶性高分子（Ｙ）を含み、上記水溶性高分子（Ｘ）は、下記一般式（Ｂ－２）で表される構成成分を２０質量％以上含む重合体であり、上記水溶性高分子（Ｘ）の重量平均分子量に対する上記水溶性高分子（Ｙ）の重量平均分子量の比が０．３００～１０．０である、二次電池用バインダー組成物。
Figure JPOXMLDOC01-appb-C000002
 　一般式（Ｂ－２）中、Ｒ２１～Ｒ２３は水素原子、シアノ基又は炭素数１～６のアルキル基を示し、Ｒ２４は水素原子、アシル基、ヒドロキシ基、フェニル基又はカルボキシ基を示し、Ｌ２１は単結合、炭素数１～１６のアルキレン基、炭素数６～１２のアリーレン基、酸素原子、硫黄原子、カルボニル基若しくはイミノ基、又はこれらを組み合わせた連結基を示す。＊は上記水溶性高分子（Ｘ）の主鎖中に組み込まれるための結合部位を示す。
＜２＞
　上記水溶性高分子（Ｘ）中、上記一般式（Ｂ－２）で表される構成成分の含有量が８０質量％以上である、＜１＞に記載の二次電池用バインダー組成物。
＜３＞
　上記一般式（Ｂ－２）で表される構成成分が（メタ）アクリルアミド成分を含む、＜１＞又は＜２＞に記載の二次電池用バインダー組成物。
＜４＞
　上記水溶性高分子（Ｘ）が、アクリロニトリル成分及びＮ－ビニル－２－ピロリドン成分の少なくとも１種を、更に含む重合体である、＜１＞～＜３＞のいずれか１つに記載の二次電池用バインダー組成物。
＜５＞
　上記水溶性高分子（Ｘ）の重量平均分子量が１００００～１００００００である、＜１＞～＜４＞のいずれか１つに記載の二次電池用バインダー組成物。
＜６＞
　上記水溶性高分子（Ｘ）の分子量分布が５．０以下である、＜１＞～＜５＞のいずれか１つに記載の二次電池用バインダー組成物。
＜７＞
　上記水溶性高分子（Ｙ）が多糖類である、＜１＞～＜６＞のいずれか１つに記載の二次電池用バインダー組成物。
＜８＞
　上記水溶性高分子（Ｙ）が、カルボキシメチルセルロース、ヒドロキシエチルセルロース、ヒドロキシプロピルセルロース及びキサンタンガムの少なくとも１種を含む、＜７＞に記載の二次電池用バインダー組成物。
＜９＞
　上記水溶性高分子（Ｙ）の重量平均分子量が１０００００～５０００００である、＜１＞～＜８＞のいずれか１つに記載の二次電池用バインダー組成物。
＜１０＞
　重合体粒子を含む、＜１＞～＜９＞のいずれか１つに記載の二次電池用バインダー組成物。
＜１１＞
　上記重合体粒子を構成する重合体が、共役ジエン成分、エチレン性不飽和カルボン酸成分、シアノ基含有エチレン性モノマー成分及び芳香族ビニルモノマー成分の少なくとも１種を含む重合体である、＜１０＞に記載の二次電池用バインダー組成物。
＜１２＞
　水を含む、＜１＞～＜１１＞のいずれか１つに記載の二次電池用バインダー組成物。
＜１３＞
　周期律表第１族又は第２族に属する金属のイオンの挿入放出が可能な活物質を含む、＜１＞～＜１２＞のいずれか１つに記載の二次電池用バインダー組成物。
＜１４＞
　上記活物質がケイ素系活物質を含む、＜１３＞に記載の二次電池用バインダー組成物。
＜１５＞
　＜１３＞又は＜１４＞に記載の二次電池用バインダー組成物を用いて形成された層を有する電極シート。
＜１６＞
　正極活物質層及び負極活物質層の少なくとも１つの層が、＜１３＞又は＜１４＞に記載の二次電池用バインダー組成物を用いて形成された層である、二次電池。
＜１７＞
　＜１３＞又は＜１４＞に記載の二次電池用バインダー組成物を用いて電極活物質層を形成することを含む、電極シートの製造方法。
＜１８＞
　＜１７＞に記載の製造方法により得られた電極シートを二次電池の電極として組み込むことを含む、二次電池の製造方法。 That is, the above-mentioned problems of the present invention were solved by the following means.
<1>
A polymer containing a water-soluble polymer (X) and a water-soluble polymer (Y), where the water-soluble polymer (X) contains 20% by mass or more of a constituent represented by the following general formula (B-2). A binder composition for a secondary battery, wherein the ratio of the weight average molecular weight of the water-soluble polymer (Y) to the weight average molecular weight of the water-soluble polymer (X) is 0.300 to 10.0.
Figure JPOXMLDOC01-appb-C000002
 In the general formula (B-2), R 21 to R 23 represent a hydrogen atom, a cyano group, or an alkyl group having 1 to 6 carbon atoms, and R 24 represents a hydrogen atom, an acyl group, a hydroxy group, a phenyl group, or a carboxy group. and L 21 represents a single bond, an alkylene group having 1 to 16 carbon atoms, an arylene group having 6 to 12 carbon atoms, an oxygen atom, a sulfur atom, a carbonyl group, an imino group, or a linking group combining these. * indicates a binding site for incorporation into the main chain of the water-soluble polymer (X).
<2>
The binder composition for a secondary battery according to <1>, wherein the content of the component represented by the general formula (B-2) in the water-soluble polymer (X) is 80% by mass or more.
<3>
The binder composition for a secondary battery according to <1> or <2>, wherein the component represented by the general formula (B-2) includes a (meth)acrylamide component.
<4>
The polymer according to any one of <1> to <3>, wherein the water-soluble polymer (X) is a polymer further containing at least one of an acrylonitrile component and an N-vinyl-2-pyrrolidone component. Binder composition for secondary batteries.
<5>
The binder composition for a secondary battery according to any one of <1> to <4>, wherein the water-soluble polymer (X) has a weight average molecular weight of 10,000 to 1,000,000.
<6>
The binder composition for a secondary battery according to any one of <1> to <5>, wherein the water-soluble polymer (X) has a molecular weight distribution of 5.0 or less.
<7>
The binder composition for a secondary battery according to any one of <1> to <6>, wherein the water-soluble polymer (Y) is a polysaccharide.
<8>
The binder composition for a secondary battery according to <7>, wherein the water-soluble polymer (Y) contains at least one of carboxymethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, and xanthan gum.
<9>
The binder composition for a secondary battery according to any one of <1> to <8>, wherein the water-soluble polymer (Y) has a weight average molecular weight of 100,000 to 500,000.
<10>
The binder composition for a secondary battery according to any one of <1> to <9>, which contains polymer particles.
<11>
<10> The polymer constituting the polymer particles is a polymer containing at least one of a conjugated diene component, an ethylenically unsaturated carboxylic acid component, a cyano group-containing ethylenic monomer component, and an aromatic vinyl monomer component. A binder composition for secondary batteries as described in .
<12>
The binder composition for a secondary battery according to any one of <1> to <11>, which contains water.
<13>
The binder composition for a secondary battery according to any one of <1> to <12>, which contains an active material capable of inserting and releasing ions of metals belonging to Group 1 or Group 2 of the Periodic Table.
<14>
The binder composition for a secondary battery according to <13>, wherein the active material includes a silicon-based active material.
<15>
An electrode sheet having a layer formed using the binder composition for secondary batteries according to <13> or <14>.
<16>
A secondary battery, wherein at least one of the positive electrode active material layer and the negative electrode active material layer is a layer formed using the binder composition for a secondary battery according to <13> or <14>.
<17>
A method for manufacturing an electrode sheet, comprising forming an electrode active material layer using the binder composition for secondary batteries according to <13> or <14>.
<18>
A method for manufacturing a secondary battery, comprising incorporating an electrode sheet obtained by the manufacturing method according to <17> as an electrode of a secondary battery.
　本発明において、「水溶性高分子」とは、２０℃において水に対する溶解度が１０ｇ／Ｌ－Ｈ２Ｏ以上であるポリマー、すなわち、２０℃において水１リットルに対して１０ｇ以上溶解するポリマーを意味する。「水溶性高分子」の上記溶解度は１００ｇ／Ｌ－Ｈ２Ｏ以上であることが好ましい。
　本発明において、「～」を用いて表される数値範囲は、「～」の前後に記載される数値を下限値及び上限値として含む範囲を意味する。
　本発明において化合物、構成成分又は置換基の表示については、本発明の効果を奏する範囲で、構造の一部を変化させたものを含む意味である。更に、本発明において置換又は無置換を明記していない化合物又は構成成分については、本発明の効果を奏する範囲で、任意の置換基を有していてもよい意味である。このことは、置換基（例えば、「アルキル基」、「メチル基」、「メチル」等のように表現される基）及び連結基（例えば、「アルキレン基」、「メチレン基」、「メチレン」等のように表現される基）についても同様である。このような任意の置換基のうち、本発明において好ましい置換基は、後述の置換基群Ｔから選択される置換基である。
　本発明において、特定の符号又は式で示された置換基若しくは連結基等（以下、置換基等という）が複数あるとき、又は複数の置換基等を同時に規定するときには、特段の断りがない限り、それぞれの置換基等は互いに同一でも異なっていてもよい。このことは、ポリマーの構成成分についても同様である。
　本発明において、各成分は１種含有されていてもよく、２種以上含有されていてもよい。
　本発明において、（メタ）アクリルとは、アクリル及びメタアクリルの一方又は両方を意味する。（メタ）アクリレートについても同様である。
　本発明において「二次電池」とは、充放電により電解質を介して正負極間をイオンが通過し、正負極においてエネルギーを貯蔵、放出するデバイス全般を意味する。すなわち、本発明において二次電池という場合、電池とキャパシタ（例えば、リチウムイオンキャパシタ）の両方を包含する意味である。エネルギー貯蔵量の観点から、本発明の二次電池は電池用途に用いること（キャパシタでないこと）が好ましい。
　二次電池は、用いる電解質に応じて水系二次電池と非水系二次電池とに大別でき、本発明においては、非水系二次電池が好ましい。本発明において「水系二次電池」とは、電解質として水系電解液を用いた二次電池を意味する。本発明において「非水系二次電池」とは、非水電解液二次電池と全固体二次電池とを含む意味である。本発明において「非水電解液二次電池」とは、電解質として非水電解液を用いた二次電池を意味する。本発明において「非水電解液」とは、水を実質的に含まない電解液を意味する。水を実質的に含まない電解液とは、「非水電解液」が本発明の効果を妨げない範囲で微量の水を含んでいてもよいことを意味する。本発明において「非水電解液」は、水の濃度が２００ｐｐｍ（質量基準）以下であり、１００ｐｐｍ以下が好ましく、２０ｐｐｍ以下がより好ましい。なお、非水電解液を完全に無水とすることは現実的に困難であり、通常は水が１ｐｐｍ以上含まれる。本発明において「全固体二次電池」とは、電解質として液を用いず、無機固体電解質、固体状ポリマー電解質等の固体電解質を用いた二次電池を意味する。
　本発明において、ある基の炭素数を規定する場合、この炭素数は、本発明ないし本明細書において特段の断りのない限りは、基そのものの炭素数を意味する。つまり、この基が更に置換基を有する形態である場合、この置換基の炭素数は含まずに数えた場合の炭素数を意味する。
　本発明において、含有量又は含有割合を記載する場合に使用する「固形分」とは、後述する水及び液媒体以外の成分を意味する。 In the present invention, "water-soluble polymer" means a polymer whose solubility in water is 10 g/L-H 2 O or more at 20°C, that is, a polymer that dissolves 10 g or more in 1 liter of water at 20°C. do. The solubility of the "water-soluble polymer" is preferably 100 g/L-H 2 O or more.
In the present invention, a numerical range expressed using "~" means a range that includes the numerical values written before and after "~" as lower and upper limits.
In the present invention, the expression of a compound, a constituent component, or a substituent is meant to include those whose structures are partially changed within the range that exhibits the effects of the present invention. Further, in the present invention, compounds or constituent components that are not specified as being substituted or unsubstituted may have any substituent as long as the effects of the present invention are achieved. This applies to substituents (e.g., groups expressed as "alkyl group,""methylgroup,""methyl," etc.) and linking groups (e.g., "alkylene group,""methylenegroup,""methylenegroup," etc.) The same applies to groups expressed as such. Among such arbitrary substituents, preferred substituents in the present invention are substituents selected from substituent group T described below.
In the present invention, when there are multiple substituents or linking groups, etc. (hereinafter referred to as substituents, etc.) indicated by a specific symbol or formula, or when multiple substituents, etc. are specified at the same time, unless otherwise specified, , each substituent, etc. may be the same or different from each other. This also applies to the constituent components of the polymer.
In the present invention, one type of each component may be contained, or two or more types of each component may be contained.
In the present invention, (meth)acrylic means one or both of acrylic and methacrylic. The same applies to (meth)acrylate.
In the present invention, the term "secondary battery" refers to any device in which ions pass between positive and negative electrodes via an electrolyte during charging and discharging, and energy is stored and released at the positive and negative electrodes. That is, in the present invention, the term "secondary battery" includes both a battery and a capacitor (for example, a lithium ion capacitor). From the viewpoint of energy storage capacity, the secondary battery of the present invention is preferably used for battery applications (not as a capacitor).
Secondary batteries can be roughly classified into aqueous secondary batteries and non-aqueous secondary batteries depending on the electrolyte used, and in the present invention, non-aqueous secondary batteries are preferred. In the present invention, the term "aqueous secondary battery" refers to a secondary battery using an aqueous electrolyte as an electrolyte. In the present invention, the term "non-aqueous secondary battery" includes non-aqueous electrolyte secondary batteries and all-solid-state secondary batteries. In the present invention, a "non-aqueous electrolyte secondary battery" means a secondary battery using a non-aqueous electrolyte as an electrolyte. In the present invention, the term "non-aqueous electrolyte" means an electrolyte that does not substantially contain water. An electrolytic solution that does not substantially contain water means that the "non-aqueous electrolytic solution" may contain a trace amount of water as long as it does not impede the effects of the present invention. In the present invention, the "nonaqueous electrolyte" has a water concentration of 200 ppm or less (based on mass), preferably 100 ppm or less, and more preferably 20 ppm or less. Note that it is practically difficult to make the nonaqueous electrolyte completely anhydrous, and it usually contains 1 ppm or more of water. In the present invention, the term "all-solid secondary battery" refers to a secondary battery that uses a solid electrolyte such as an inorganic solid electrolyte or a solid polymer electrolyte without using a liquid as an electrolyte.
In the present invention, when specifying the number of carbon atoms in a certain group, this number of carbon atoms means the number of carbon atoms in the group itself unless otherwise specified in the present invention or this specification. In other words, when this group further has a substituent, it means the number of carbon atoms not including the number of carbon atoms of this substituent.
In the present invention, the "solid content" used when describing the content or content ratio means components other than water and the liquid medium described below.
　本発明の二次電池用バインダー組成物及び電極シートは、充放電時の体積変化の大きな電極活物質を用いた場合でも、得られる二次電池のサイクル寿命を十分に長期化することができる。
　本発明の二次電池は、充放電時の体積変化の大きな電極活物質を用いた場合にも、十分に長いサイクル寿命を実現できる。
　本発明の電極シートの製造方法によれば、本発明の上記電極シートを得ることができる。また、本発明の二次電池の製造方法によれば、本発明の上記二次電池を得ることができる。 The binder composition and electrode sheet for a secondary battery of the present invention can sufficiently extend the cycle life of the resulting secondary battery even when an electrode active material that exhibits a large volume change during charging and discharging is used.
The secondary battery of the present invention can achieve a sufficiently long cycle life even when using an electrode active material that exhibits a large volume change during charging and discharging.
According to the method for manufacturing an electrode sheet of the present invention, the above electrode sheet of the present invention can be obtained. Moreover, according to the method for manufacturing a secondary battery of the present invention, the above-mentioned secondary battery of the present invention can be obtained.
図１は、本発明に係る二次電池の一実施形態について、基本的な積層構成を模式化して示す縦断面図である。FIG. 1 is a vertical cross-sectional view schematically showing the basic stacked structure of an embodiment of a secondary battery according to the present invention.
［二次電池用バインダー組成物］
　本発明の二次電池用バインダー組成物（以降、「本発明のバインダー組成物」とも称す。）は、水溶性高分子（Ｘ）及び水溶性高分子（Ｙ）を含み、上記水溶性高分子（Ｘ）は、後述の一般式（Ｂ－２）で表される構成成分を２０質量％以上含む重合体であり、上記水溶性高分子（Ｘ）の重量平均分子量に対する上記水溶性高分子（Ｙ）の重量平均分子量の比が０．３００～１０．０である。
　本発明のバインダー組成物は、好ましくは非水系二次電池、より好ましくは非水電解液二次電池を構成する部材ないし構成層の形成に用いるのに好適である。本発明のバインダー組成物は、液媒体として、好ましくは水を含有する。典型的には、本発明のバインダー組成物は、二次電池の電極（正極又は負極）における電極活物質層の形成に好適に用いることができる。例えば、本発明のバインダー組成物に電極活物質（正極活物質又は負極活物質、これらを合わせて、単に「活物質」とも称す。）を含有させて二次電池の電極（正極又は負極）活物質層の形成に用いることができる。 [Binder composition for secondary batteries]
The binder composition for secondary batteries of the present invention (hereinafter also referred to as "the binder composition of the present invention") includes a water-soluble polymer (X) and a water-soluble polymer (Y), and the water-soluble polymer (X) is a polymer containing 20% by mass or more of a component represented by the general formula (B-2) described below, and the water-soluble polymer ( The weight average molecular weight ratio of Y) is 0.300 to 10.0.
The binder composition of the present invention is preferably used for forming members or constituent layers constituting a non-aqueous secondary battery, more preferably a non-aqueous electrolyte secondary battery. The binder composition of the present invention preferably contains water as the liquid medium. Typically, the binder composition of the present invention can be suitably used for forming an electrode active material layer in an electrode (positive electrode or negative electrode) of a secondary battery. For example, the binder composition of the present invention may contain an electrode active material (a positive electrode active material or a negative electrode active material, together referred to simply as "active material") to activate the electrode (positive electrode or negative electrode) of a secondary battery. It can be used to form a material layer.
　本発明のバインダー組成物が含有する水溶性高分子（Ｘ）及び本発明のバインダー組成物が含有していてもよい後述の重合体粒子は、例えば、本発明のバインダー組成物と固体粒子（電極活物質、導電助剤等）とを混合して形成した層中において、主として、これらの固体粒子同士を結着させる結着剤（バインダー）として機能すると考えられる。また、集電体と固体粒子とを結着させる結着剤としても機能し得る。水溶性高分子（Ｘ）及び重合体粒子の固体粒子及び集電体に対する吸着は、物理的吸着だけでなく、化学的吸着（化学結合形成による吸着、電子の授受による吸着等）も含む。
　一方、本発明のバインダー組成物が含有する水溶性高分子（Ｙ）は、主として、本発明のバインダー組成物中で増粘剤（分散剤）として機能するものと考えられる。 The water-soluble polymer (X) contained in the binder composition of the present invention and the below-mentioned polymer particles which may be contained in the binder composition of the present invention can be combined with the binder composition of the present invention and solid particles (electrode It is thought that in the layer formed by mixing the solid particles (active material, conductive aid, etc.), it functions mainly as a binding agent (binder) that binds these solid particles together. It can also function as a binder that binds the current collector and solid particles. The adsorption of water-soluble polymer (X) and polymer particles to solid particles and current collectors includes not only physical adsorption but also chemical adsorption (adsorption due to chemical bond formation, adsorption due to exchange of electrons, etc.).
On the other hand, the water-soluble polymer (Y) contained in the binder composition of the present invention is considered to mainly function as a thickener (dispersant) in the binder composition of the present invention.
　本発明のバインダー組成物は、例えば、活物質を含む形態で電極シートを作製して、これを二次電池の電極に適用することで二次電池のサイクル特性を向上させることができる。この理由は定かではないが、以下のように考えられる。
　本発明のバインダー組成物は水溶性高分子（Ｙ）を含有することにより増粘し、バインダー組成物の分散性が高められている。したがって、このバインダー組成物を用いて形成される電極活物質層中においても、水溶性高分子（Ｘ）、水溶性高分子（Ｙ）、及び活物質等の固体粒子が実質的に均一に分散して存在することができる。そして、水溶性高分子（Ｘ）が後述の一般式（Ｂ－２）で表される特定の構造の構成成分を２０質量％以上含有し、かつ、水溶性高分子（Ｘ）の重量平均分子量に対する水溶性高分子（Ｙ）の重量平均分子量の比が０．３００～１０．０となることにより、水素結合等の分子間結合の形成により水溶性高分子（Ｘ）と水溶性高分子（Ｙ）の相互作用が促進され、水溶性高分子（Ｘ）と水溶性高分子（Ｙ）の複合物の破断エネルギーが向上し、更に固体粒子等の結着性も向上することで、二次電池の充放電に伴う電極活物質の体積変化に対しても導通状態を良好に維持できることが、二次電池のサイクル特性向上の一因と考えられる。 The binder composition of the present invention can improve the cycle characteristics of a secondary battery by, for example, producing an electrode sheet in a form containing an active material and applying this to an electrode of a secondary battery. Although the reason for this is not certain, it is thought to be as follows.
The binder composition of the present invention is thickened by containing the water-soluble polymer (Y), and the dispersibility of the binder composition is improved. Therefore, even in the electrode active material layer formed using this binder composition, solid particles such as the water-soluble polymer (X), the water-soluble polymer (Y), and the active material are substantially uniformly dispersed. can exist. The water-soluble polymer (X) contains 20% by mass or more of a component having a specific structure represented by the general formula (B-2) described below, and the weight average molecular weight of the water-soluble polymer (X) is When the ratio of the weight average molecular weight of the water-soluble polymer (Y) to the water-soluble polymer (Y) is 0.300 to 10.0, the water-soluble polymer (X) and the water-soluble polymer ( Y) interaction is promoted, the fracture energy of the composite of water-soluble polymer (X) and water-soluble polymer (Y) is improved, and the binding properties of solid particles, etc. are also improved. The ability to maintain a good conduction state even when the electrode active material changes in volume as the battery is charged and discharged is thought to be one of the reasons for improving the cycle characteristics of the secondary battery.
　以下に本発明のバインダー組成物が含む成分について説明する。 The components contained in the binder composition of the present invention will be explained below.
（水溶性高分子（Ｘ））
　水溶性高分子（Ｘ）は、下記一般式（Ｂ－２）で表される構成成分を２０質量％以上含む重合体である。 (Water-soluble polymer (X))
The water-soluble polymer (X) is a polymer containing 20% by mass or more of a component represented by the following general formula (B-2).
Figure JPOXMLDOC01-appb-C000003
Figure JPOXMLDOC01-appb-C000003
　一般式（Ｂ－２）中、Ｒ２１～Ｒ２３は水素原子、シアノ基又は炭素数１～６のアルキル基を示す。この炭素数１～６のアルキル基は直鎖でも分岐を有してもよい。この炭素数１～６のアルキル基は、炭素数１～４のアルキル基が好ましく、メチル又はエチルがより好ましく、メチルが更に好ましい。
　Ｒ２１及びＲ２２としては、水素原子が好ましい。
　Ｒ２３としては、水素原子又はメチル基が好ましく、水素原子がより好ましい。
　Ｒ２４は水素原子、アシル基（アルキルカルボニル基）、ヒドロキシ基、フェニル基又はカルボキシ基を示す。アシル基中のアルキル基としては、例えば、後述の置換基群Ｔにおけるアルキル基が挙げられ、直鎖でも分岐を有してもよく、Ｒ２１～Ｒ２３として採り得る炭素数１～６のアルキル基を好ましく採用することができる。
　Ｒ２４としては、水素原子又はヒドロキシ基が好ましく、水素原子がより好ましい。 In the general formula (B-2), R 21 to R 23 represent a hydrogen atom, a cyano group, or an alkyl group having 1 to 6 carbon atoms. This alkyl group having 1 to 6 carbon atoms may be linear or branched. The alkyl group having 1 to 6 carbon atoms is preferably an alkyl group having 1 to 4 carbon atoms, more preferably methyl or ethyl, and even more preferably methyl.
A hydrogen atom is preferable as R 21 and R 22 .
R23 is preferably a hydrogen atom or a methyl group, more preferably a hydrogen atom.
R24 represents a hydrogen atom, an acyl group (alkylcarbonyl group), a hydroxy group, a phenyl group, or a carboxy group. Examples of the alkyl group in the acyl group include the alkyl group in the substituent group T described below, which may be straight chain or branched, and may be an alkyl group having 1 to 6 carbon atoms that can be taken as R 21 to R 23 . groups can be preferably employed.
R24 is preferably a hydrogen atom or a hydroxy group, more preferably a hydrogen atom.
　Ｌ２１は単結合、炭素数１～１６のアルキレン基、炭素数６～１２のアリーレン基、酸素原子（－Ｏ－）、硫黄原子（－Ｓ－）、カルボニル基（＞Ｃ＝Ｏ）若しくはイミノ基（＞ＮＲＮ）、又はこれらを組み合わせた連結基を示す。また、後述のように、Ｌ２１は後記する置換基群Ｔから選ばれる置換基を有していてもよく、この置換基としては、ヒドロキシ基が好ましい。
　上記ＲＮは、水素原子又はアルキル基を示す。
　Ｌ２１が単結合以外の連結基を示す場合、Ｌ２１の化学式量は１４～２０００が好ましく、１４～５００がより好ましく、２８～２００が更に好ましい。Ｌ２１が有しうる炭素数１～１６のアルキレン基は直鎖でも分岐を有してもよい。このアルキレン基の炭素数は１～１２が好ましく、１～１０がより好ましく、１～６が更に好ましく、１～４が特に好ましい。
　Ｌ２１としては、単結合、メチレン、エチレン、プロピレン、２－ヒドロキシプロピレン又はブチレンが好ましく、単結合、エチレン基又はブチレン基がより好ましく、単結合又はエチレン基がさらに好ましく、単結合が特に好ましい。
　＊は上記ポリマー（水溶性高分子（Ｘ））の主鎖中に組み込まれるための結合部位を示す。 L21 is a single bond, an alkylene group having 1 to 16 carbon atoms, an arylene group having 6 to 12 carbon atoms, an oxygen atom (-O-), a sulfur atom (-S-), a carbonyl group (>C=O), or an imino group. Indicates a group (>NR N ) or a linking group that is a combination of these. Further, as described later, L 21 may have a substituent selected from the substituent group T described later, and this substituent is preferably a hydroxy group.
The above R N represents a hydrogen atom or an alkyl group.
When L 21 represents a linking group other than a single bond, the chemical formula weight of L 21 is preferably from 14 to 2,000, more preferably from 14 to 500, even more preferably from 28 to 200. The alkylene group having 1 to 16 carbon atoms that L 21 may have may be linear or branched. The alkylene group preferably has 1 to 12 carbon atoms, more preferably 1 to 10 carbon atoms, even more preferably 1 to 6 carbon atoms, and particularly preferably 1 to 4 carbon atoms.
L 21 is preferably a single bond, methylene, ethylene, propylene, 2-hydroxypropylene or butylene, more preferably a single bond, ethylene group or butylene group, even more preferably a single bond or ethylene group, and particularly preferably a single bond.
* indicates a bonding site for incorporation into the main chain of the above polymer (water-soluble polymer (X)).
　上記一般式（Ｂ－２）で表される構成成分の具体例としては、（メタ）アクリルアミド成分；Ｎ－（２－ヒドロキシエチル）（メタ）アクリルアミド成分等のＮ－（ヒドロキシアルキル）（メタ）アクリルアミド成分が挙げられ、（メタ）アクリルアミド成分が好ましく、アクリルアミド成分がより好ましい。 Specific examples of the components represented by the above general formula (B-2) include (meth)acrylamide component; N-(hydroxyalkyl)(meth) such as N-(2-hydroxyethyl)(meth)acrylamide component; Acrylamide components are mentioned, (meth)acrylamide components are preferred, and acrylamide components are more preferred.
　水溶性高分子（Ｘ）は、電極活物質層の体積変化を効果的に抑制してサイクル特性を向上させる観点から、（メタ）アクリルアミド成分を含むことが好ましく、アクリルアミド成分を含むことがより好ましい。
　一般式（Ｂ－２）で表される構成成分中における（メタ）アクリルアミド成分（好ましくはアクリルアミド成分）の含有量は、５０質量％以上が好ましく、７０質量％以上がより好ましく、９０質量％以上が更に好ましく、９５質量％以上が特に好ましく、１００質量％であってもよい。 The water-soluble polymer (X) preferably contains a (meth)acrylamide component, and more preferably contains an acrylamide component, from the viewpoint of effectively suppressing the volume change of the electrode active material layer and improving cycle characteristics. .
The content of the (meth)acrylamide component (preferably the acrylamide component) in the component represented by general formula (B-2) is preferably 50% by mass or more, more preferably 70% by mass or more, and 90% by mass or more. is more preferred, 95% by mass or more is particularly preferred, and may be 100% by mass.
　本発明に用いられる水溶性高分子（Ｘ）は、本発明の効果を損なわない範囲内で、上記一般式（Ｂ－２）で表される構成成分以外の構成成分を含んでもよく、このような構成成分として、下記一般式（Ｂ－１）で表される構成成分、並びに、下記一般式（Ｂ－１）で表される構成成分とは異なる構成成分としてアクリロニトリル成分、Ｎ－ビニル－２－ピロリドン成分及びスチレン成分挙げられ、アクリロニトリル成分及びＮ－ビニル－２－ピロリドン成分のうちの少なくとも１種を含むことが好ましく、アクリロニトリル成分を含むことがより好ましい。 The water-soluble polymer (X) used in the present invention may contain components other than those represented by the above general formula (B-2) within a range that does not impair the effects of the present invention. As a constituent component, a constituent component represented by the following general formula (B-1), and acrylonitrile component, N-vinyl-2 as a constituent component different from the constituent component represented by the following general formula (B-1). -pyrrolidone component and styrene component, preferably includes at least one of an acrylonitrile component and an N-vinyl-2-pyrrolidone component, and more preferably an acrylonitrile component.
Figure JPOXMLDOC01-appb-C000004
Figure JPOXMLDOC01-appb-C000004
　一般式（Ｂ－１）中、Ｒ１１～Ｒ１３は水素原子、シアノ基又は炭素数１～６のアルキル基を示す。この炭素数１～６のアルキル基は直鎖でも分岐を有してもよい。この炭素数１～６のアルキル基は、炭素数１～４のアルキル基が好ましく、メチル又はエチルがより好ましく、メチルが更に好ましい。
　Ｒ１１及びＲ１２としては、水素原子が好ましい。
　Ｒ１３としては、水素原子又はメチル基が好ましく、水素原子がより好ましい。
　Ｒ１４は水素原子、ヒドロキシ基、炭素数１～６のアルコキシ基（アルキルオキシ基）、シアノ基、フェニル基、カルボキシ基、スルホ基（－Ｓ（＝Ｏ）２（ＯＨ））、リン酸基（－ＯＰ（＝Ｏ）（ＯＨ）２）又はホスホン酸基（－Ｐ（＝Ｏ）（ＯＨ）２）を示す。上記の炭素数１～６のアルコキシ基中のアルキル基は直鎖でも分岐を有してもよい。この炭素数１～６のアルコキシ基は、炭素数１～４のアルコキシ基が好ましく、メトキシ又はエトキシがより好ましい。
　Ｒ１４としては、水素原子、ヒドロキシ基、メトキシ基又はエトキシ基が好ましく、水素原子がより好ましい。 In general formula (B-1), R 11 to R 13 represent a hydrogen atom, a cyano group, or an alkyl group having 1 to 6 carbon atoms. This alkyl group having 1 to 6 carbon atoms may be linear or branched. The alkyl group having 1 to 6 carbon atoms is preferably an alkyl group having 1 to 4 carbon atoms, more preferably methyl or ethyl, and even more preferably methyl.
A hydrogen atom is preferable as R 11 and R 12 .
R 13 is preferably a hydrogen atom or a methyl group, more preferably a hydrogen atom.
R14 is a hydrogen atom, a hydroxy group, an alkoxy group having 1 to 6 carbon atoms (alkyloxy group), a cyano group, a phenyl group, a carboxy group, a sulfo group (-S(=O) 2 (OH)), a phosphoric acid group (-OP(=O)(OH) 2 ) or a phosphonic acid group (-P(=O)(OH) 2 ). The alkyl group in the above alkoxy group having 1 to 6 carbon atoms may be linear or branched. The alkoxy group having 1 to 6 carbon atoms is preferably an alkoxy group having 1 to 4 carbon atoms, more preferably methoxy or ethoxy.
R 14 is preferably a hydrogen atom, a hydroxy group, a methoxy group or an ethoxy group, and more preferably a hydrogen atom.
　Ｌ１１は単結合、炭素数１～１６のアルキレン基、炭素数６～１２のアリーレン基、酸素原子（－Ｏ－）、硫黄原子（－Ｓ－）、カルボニル基（＞Ｃ＝Ｏ）若しくはイミノ基（＞ＮＲＮ）、又はこれらを組み合わせた連結基を示す。また、後述のように、Ｌ１１は後述の置換基群Ｔから選ばれる置換基を有していてもよく、この置換基としては、ヒドロキシ基が好ましい。
　上記ＲＮは、水素原子又はアルキル基を示す。
　Ｌ１１が単結合以外の連結基を示す場合、Ｌ１１の化学式量は１４～２０００が好ましく、１４～５００がより好ましく、２８～２００が更に好ましい。Ｌ１１が有しうる炭素数１～１６のアルキレン基は直鎖でも分岐を有してもよい。このアルキレン基の炭素数は１～１２が好ましく、１～１０がより好ましく、１～６が更に好ましく、１～４が特に好ましい。
　Ｌ１１としては、単結合、メチレン、エチレン、プロピレン、２－ヒドロキシプロピレン又はブチレンが好ましく、単結合、エチレン基又はブチレン基がより好ましい。
　＊は上記ポリマー（水溶性高分子（Ｘ））主鎖中に組み込まれるための結合部位を示す。 L 11 is a single bond, an alkylene group having 1 to 16 carbon atoms, an arylene group having 6 to 12 carbon atoms, an oxygen atom (-O-), a sulfur atom (-S-), a carbonyl group (>C=O), or an imino group. Indicates a group (>NR N ) or a linking group that is a combination of these. Further, as described below, L 11 may have a substituent selected from the substituent group T described below, and this substituent is preferably a hydroxy group.
The above R N represents a hydrogen atom or an alkyl group.
When L 11 represents a linking group other than a single bond, the chemical formula weight of L 11 is preferably from 14 to 2,000, more preferably from 14 to 500, even more preferably from 28 to 200. The alkylene group having 1 to 16 carbon atoms that L 11 may have may be linear or branched. The alkylene group preferably has 1 to 12 carbon atoms, more preferably 1 to 10 carbon atoms, even more preferably 1 to 6 carbon atoms, and particularly preferably 1 to 4 carbon atoms.
L 11 is preferably a single bond, methylene, ethylene, propylene, 2-hydroxypropylene or butylene, and more preferably a single bond, ethylene group or butylene group.
* indicates a bonding site for incorporation into the main chain of the above polymer (water-soluble polymer (X)).
　上記一般式（Ｂ－１）で表される構成成分の具体例としては、（メタ）アクリル酸成分；（メタ）アクリル酸メチル成分、（メタ）アクリル酸エチル成分、（メタ）アクリル酸プロピル成分及び（メタ）アクリル酸ブチル成分等の（メタ）アクリル酸アルキル成分；２－ヒドロキシエチル（メタ）アクリレート成分、４－ヒドロキシブチル（メタ）アクリレート成分、２，３－ジヒドロキシプロピル（メタ）アクリレート成分等のヒドロキシアルキル（メタ）アクリレート成分；メトキシエチル（メタ）アクリレート成分、エトキシエチル（メタ）アクリレート成分等のアルコキシアルキル（メタ）アクリレート成分が挙げられ、（メタ）アクリル酸成分又はヒドロキシアルキル（メタ）アクリレート成分が好ましい。 Specific examples of the components represented by the above general formula (B-1) include (meth)acrylic acid component; methyl (meth)acrylate component, ethyl (meth)acrylate component, and propyl (meth)acrylate component. and alkyl (meth)acrylate components such as butyl (meth)acrylate components; 2-hydroxyethyl (meth)acrylate component, 4-hydroxybutyl (meth)acrylate component, 2,3-dihydroxypropyl (meth)acrylate component, etc. hydroxyalkyl (meth)acrylate component; examples include alkoxyalkyl (meth)acrylate components such as methoxyethyl (meth)acrylate component and ethoxyethyl (meth)acrylate component; (meth)acrylic acid component or hydroxyalkyl (meth)acrylate Ingredients are preferred.
　なお、水溶性高分子（Ｘ）に含まれる構成成分の種類は特に制限されず、１～１０種が好ましく、１～５種がより好ましく、１～３種がさらに好ましく、１種又は２種が特に好ましい。後述する水溶性高分子（Ｘ）の具体例では、構成成分の種類が１種又は２種の重合体を記載している。この具体例において、構成成分の種類が１種の重合体はポリアクリルアミドである。 The types of constituent components contained in the water-soluble polymer (X) are not particularly limited, and are preferably 1 to 10 types, more preferably 1 to 5 types, even more preferably 1 to 3 types, and 1 type or 2 types. is particularly preferred. In the specific examples of the water-soluble polymer (X) described below, polymers having one or two types of constituent components are described. In this specific example, the single component type polymer is polyacrylamide.
　水溶性高分子（Ｘ）中、上記一般式（Ｂ－２）で表される構成成分の含有量は、２０質量％以上であり、４０質量％以上が好ましく、６０質量％以上がより好ましく、８０質量％以上が更に好ましく、８５質量％以上が特に好ましく、なかでも９０質量％以上が好ましく、９５質量％以上が最も好ましく、１００質量％であってもよい。上限値に特に制限はなく、１００質量％以下であればよい。
　水溶性高分子（Ｘ）中、上記一般式（Ｂ－１）で表される構成成分、並びに、上記一般式（Ｂ－１）で表される構成成分とは異なる構成成分であるアクリロニトリル成分、Ｎ－ビニル－２－ピロリドン成分及びスチレン成分の含有量は、合計で、８０質量％以下であり、６０質量％以下が好ましく、４０質量％以下がより好ましく、２０質量％以下が更に好ましく、１５質量％以下が更に好ましく、１０質量％以下が更に好ましく、５質量％以下が最も好ましい。水溶性高分子（Ｘ）は上記一般式（Ｂ－１）で表される構成成分、アクリロニトリル成分、Ｎ－ビニル－２－ピロリドン成分及びスチレン成分のいずれも含んでいないことも好ましい。 In the water-soluble polymer (X), the content of the component represented by the above general formula (B-2) is 20% by mass or more, preferably 40% by mass or more, more preferably 60% by mass or more, It is more preferably 80% by mass or more, particularly preferably 85% by mass or more, particularly preferably 90% by mass or more, most preferably 95% by mass or more, and may be 100% by mass. There is no particular restriction on the upper limit, as long as it is 100% by mass or less.
In the water-soluble polymer (X), a component represented by the above general formula (B-1), and an acrylonitrile component that is a different component from the component represented by the above general formula (B-1), The total content of the N-vinyl-2-pyrrolidone component and the styrene component is 80% by mass or less, preferably 60% by mass or less, more preferably 40% by mass or less, even more preferably 20% by mass or less, and 15% by mass or less. It is more preferably at most 10% by mass, even more preferably at most 5% by mass. It is also preferable that the water-soluble polymer (X) does not contain any of the components represented by the above general formula (B-1), an acrylonitrile component, an N-vinyl-2-pyrrolidone component, and a styrene component.
　本発明に用いられる水溶性高分子（Ｘ）の重量平均分子量（Ｍｗ）は特に制限されず、例えば、１００００～１００００００が好ましく、サイクル特性向上の観点から、１０００００～９０００００がより好ましい。下限値は、２０００００以上がより好ましく、３０００００以上がさらに好ましい。上限値は、８０００００以下がより好ましく、７０００００以下がさらに好ましい。
　水溶性高分子（Ｘ）は架橋構造を有しないこと、すなわち、鎖状高分子であることが好ましい。 The weight average molecular weight (Mw) of the water-soluble polymer (X) used in the present invention is not particularly limited, and is preferably, for example, 10,000 to 1,000,000, and more preferably 100,000 to 900,000 from the viewpoint of improving cycle characteristics. The lower limit is more preferably 200,000 or more, and even more preferably 300,000 or more. The upper limit is more preferably 800,000 or less, and even more preferably 700,000 or less.
It is preferable that the water-soluble polymer (X) does not have a crosslinked structure, that is, it is a chain polymer.
　また、サイクル特性をより向上させる観点から、水溶性高分子（Ｘ）の分子量分布は、５．０以下が好ましい。一方、水溶性高分子（Ｘ）の分子量分布は１．０以上が実際的であり好ましく、１．５以上がより好ましく、２．０以上がさらに好ましい。
　水溶性高分子（Ｘ）の分子量分布が上記好ましい範囲の値であると、水溶性高分子（Ｘ）の分子量のばらつきが抑えられ、バインダー組成物の引張弾性率の向上に寄与する水溶性高分子（Ｘ）と水溶性高分子（Ｙ）との相互作用がより発現されやすくなるため、サイクル特性がより向上されると考えられる。
　水溶性高分子（Ｘ）の分子量分布は分散度とも称され、［重量平均分子量（Ｍｗ）］／［数平均分子量（Ｍｎ）］により算出される。 Moreover, from the viewpoint of further improving cycle characteristics, the molecular weight distribution of the water-soluble polymer (X) is preferably 5.0 or less. On the other hand, the molecular weight distribution of the water-soluble polymer (X) is practically and preferably 1.0 or more, more preferably 1.5 or more, and even more preferably 2.0 or more.
When the molecular weight distribution of the water-soluble polymer (X) is within the above-mentioned preferred range, variations in the molecular weight of the water-soluble polymer (X) can be suppressed, and the water-soluble polymer can contribute to improving the tensile modulus of the binder composition. It is thought that the cycle characteristics are further improved because the interaction between the molecule (X) and the water-soluble polymer (Y) is more likely to occur.
The molecular weight distribution of the water-soluble polymer (X) is also called the degree of dispersion, and is calculated by [weight average molecular weight (Mw)]/[number average molecular weight (Mn)].
　水溶性高分子（Ｘ）の重量平均分子量に対する後述の水溶性高分子（Ｙ）の重量平均分子量の比（Ｙ／Ｘ）は０．３００～１０．０である。Ｙ／Ｘが０．３００未満であるか、又は、Ｙ／Ｘが１０．０を超えると、水溶性高分子（Ｘ）と水溶性高分子（Ｙ）の重量平均分子量の差が大きすぎるため、水溶性高分子（Ｘ）と水溶性高分子（Ｙ）との間で水素結合等の分子間結合が十分に形成しにくい等により、水溶性高分子（Ｘ）および水溶性高分子（Ｙ）の相互作用の効果が十分に得られないことに起因し、サイクル特性に劣るものと考えられる。
　Ｙ／Ｘの上限値は、７．００以下であることが好ましく、６．００以下であることがより好ましく、５．００以下であることが更に好ましく、４．００以下であることが特に好ましい。 The ratio (Y/X) of the weight average molecular weight of the water-soluble polymer (Y) described below to the weight average molecular weight of the water-soluble polymer (X) is 0.300 to 10.0. If Y/X is less than 0.300 or exceeds 10.0, the difference in weight average molecular weight between the water-soluble polymer (X) and the water-soluble polymer (Y) is too large. , because it is difficult to form sufficient intermolecular bonds such as hydrogen bonds between the water-soluble polymer (X) and the water-soluble polymer (Y). ) is considered to be due to insufficient interaction effects, resulting in poor cycle characteristics.
The upper limit of Y/X is preferably 7.00 or less, more preferably 6.00 or less, even more preferably 5.00 or less, and particularly preferably 4.00 or less. .
　水溶性高分子（Ｘ）の重量平均分子量が１００００以上７００００未満である場合、上記Ｙ／Ｘは１．５０～１０．０が好ましく、２．００～１０．０がより好ましい。
　水溶性高分子（Ｘ）の重量平均分子量が７００００以上１３００００未満である場合、上記Ｙ／Ｘは０．７００～７．００が好ましく、１．００～５．００がより好ましい。
　水溶性高分子（Ｘ）の重量平均分子量が１３００００以上２０００００未満である場合、上記Ｙ／Ｘは０．３５０～５．００が好ましく、０．６００～３．５０がより好ましい。
　水溶性高分子（Ｘ）の重量平均分子量が２０００００以上８０００００未満である場合、上記Ｙ／Ｘは０．３００～５．００が好ましく、０．３５０～４．００がより好ましい。
　水溶性高分子（Ｘ）の重量平均分子量が８０００００以上１０００００００以下である場合、上記Ｙ／Ｘは０．３００～５．００が好ましく、０．３００～４．００がより好ましい。
　なお、上記Ｙ／Ｘの有効数字は３桁である。 When the weight average molecular weight of the water-soluble polymer (X) is 10,000 or more and less than 70,000, the above Y/X is preferably 1.50 to 10.0, more preferably 2.00 to 10.0.
When the weight average molecular weight of the water-soluble polymer (X) is 70,000 or more and less than 130,000, the above Y/X is preferably 0.700 to 7.00, more preferably 1.00 to 5.00.
When the weight average molecular weight of the water-soluble polymer (X) is 130,000 or more and less than 200,000, the above Y/X is preferably 0.350 to 5.00, more preferably 0.600 to 3.50.
When the weight average molecular weight of the water-soluble polymer (X) is 200,000 or more and less than 800,000, the above Y/X is preferably 0.300 to 5.00, more preferably 0.350 to 4.00.
When the weight average molecular weight of the water-soluble polymer (X) is from 800,000 to 1,000,000, the above Y/X is preferably from 0.300 to 5.00, more preferably from 0.300 to 4.00.
Note that the significant figures of Y/X above are 3 digits.
（重量平均分子量、数平均分子量の測定）
　本発明において、水溶性高分子（Ｘ）及び水溶性高分子（Ｙ）等のポリマーの重量平均分子量及び数平均分子量については、ゲルパーミエーションクロマトグラフィー（ＧＰＣ）によって測定する。分子量は、ポリエチレングルコール換算の分子量をいう。その測定法としては、基本として下記測定条件１の方法により測定した値とする。ただし、水溶性高分子（Ｘ）及び水溶性高分子（Ｙ）等のポリマーの種類によっては適宜適切な溶離液を選定して用いればよい。
（測定条件１）
　　測定器：ＨＬＣ－８２２０ＧＰＣ（商品名、東ソー社製）
　　カラム：ＴＯＳＯＨ　ＴＳＫｇｅｌ　５０００ＰＷＸＬ（商品名、東ソー社製）、ＴＯＳＯＨ　ＴＳＫｇｅｌ　Ｇ４０００ＰＷＸＬ（商品名、東ソー社製）、ＴＯＳＯＨ　ＴＳＫｇｅｌ　Ｇ２５００ＰＷＸＬ（商品名、東ソー社製）をつなげる。
　　キャリア：２００ｍＭ　硝酸ナトリウム水溶液
　　測定温度：４０℃
　　キャリア流量：１．０ｍｌ／ｍｉｎ
　　試料濃度：０．２質量％
　　検出器：ＲＩ（屈折率）検出器
　架橋がかかっている場合など、上記測定条件１で分子量が測れない場合は下記測定条件２で静的光散乱により、分子量を測定する。
（測定条件２）
　　測定器：ＤＬＳ－８０００（商品名、大塚電子社製）
　　測定濃度：０．２５、０．５０、０．７５、１．００ｍｇ／ｍＬ
　　希釈液：０．１Ｍ　ＮａＣｌ水溶液
　　レーザー波長：６３３ｎｍ
　　ピンホール：ＰＨ１＝Ｏｐｅｎ、ＰＨ２＝Ｓｌｉｔ
　　測定角度：６０、７０、８０、９０、１００、１１０、１２０、１３０度
　　解析法：Ｚｉｍｍ平方根プロットより、分子量を測定する。解析に必要なｄｎ／ｄｃはＡｂｂｅ屈折率計で実測する。 (Measurement of weight average molecular weight and number average molecular weight)
In the present invention, the weight average molecular weight and number average molecular weight of polymers such as water-soluble polymer (X) and water-soluble polymer (Y) are measured by gel permeation chromatography (GPC). The molecular weight refers to the molecular weight in terms of polyethylene glycol. As for the measurement method, the values are basically measured according to the method of measurement condition 1 below. However, depending on the type of polymer such as water-soluble polymer (X) and water-soluble polymer (Y), an appropriate eluent may be selected and used.
(Measurement conditions 1)
Measuring instrument: HLC-8220GPC (product name, manufactured by Tosoh Corporation)
Column: TOSOH TSKgel 5000PWXL (trade name, manufactured by Tosoh Corporation), TOSOH TSKgel G4000PWXL (trade name, manufactured by Tosoh Corporation), TOSOH TSKgel G2500PWXL (trade name, manufactured by Tosoh Corporation) are connected.
Carrier: 200mM sodium nitrate aqueous solution Measurement temperature: 40°C
Carrier flow rate: 1.0ml/min
Sample concentration: 0.2% by mass
Detector: RI (refractive index) detector If the molecular weight cannot be measured under measurement condition 1 above, such as when crosslinking occurs, the molecular weight is measured by static light scattering under measurement condition 2 below.
(Measurement conditions 2)
Measuring instrument: DLS-8000 (product name, manufactured by Otsuka Electronics)
Measured concentration: 0.25, 0.50, 0.75, 1.00mg/mL
Diluent: 0.1M NaCl aqueous solution Laser wavelength: 633nm
Pinhole: PH1=Open, PH2=Slit
Measurement angle: 60, 70, 80, 90, 100, 110, 120, 130 degrees Analysis method: Measure molecular weight from Zimm square root plot. The dn/dc required for analysis is actually measured using an Abbe refractometer.
　本発明に用いられる水溶性高分子（Ｘ）の引張弾性率は、電極活物質層の体積変化を効果的に抑制してサイクル特性を向上させる観点から、３５００ＭＰａ以上が好ましく、４０００ＭＰａ以上がより好ましく、５０００ＭＰａ以上が更に好ましく、６０００ＭＰａ以上が特に好ましい。一方、上記引張弾性率は１５０００ＭＰａ以下が実際的である。
　本発明において、上記引張弾性率は後記実施例に記載のバインダー組成物の引張弾性率の算出方法において、バインダー組成物に代えて水溶性高分子（Ｘ）の水溶液を用いて試験片を作製する以外は同様にして決定することができる。 The tensile modulus of the water-soluble polymer (X) used in the present invention is preferably 3500 MPa or more, more preferably 4000 MPa or more, from the viewpoint of effectively suppressing the volume change of the electrode active material layer and improving cycle characteristics. , 5000 MPa or more is more preferable, and 6000 MPa or more is particularly preferable. On the other hand, the above tensile modulus is practically 15,000 MPa or less.
In the present invention, the above tensile modulus is determined by using an aqueous solution of water-soluble polymer (X) instead of the binder composition to prepare a test piece in the method for calculating the tensile modulus of a binder composition described in Examples below. Everything else can be determined in the same way.
　上記水溶性高分子（Ｘ）は、上述した各構造ないし部分構造において更に置換基を有していてもよく、この置換基としては、下記置換基群Ｔから選ばれる置換基が挙げられる。また、水溶性高分子（Ｘ）における各置換基については、特段の断りのない限り、下記置換基群Ｔにおける対応する置換基の記載を適用することができる。水溶性高分子（Ｘ）における各連結基についても、特段の断りのない限り、下記置換基群Ｔにおける対応する置換基から水素結合を除いて得られる連結基の記載を適用することができる。 The water-soluble polymer (X) may further have a substituent in each structure or partial structure described above, and examples of the substituent include substituents selected from the substituent group T below. Moreover, regarding each substituent in the water-soluble polymer (X), unless otherwise specified, the description of the corresponding substituent in the substituent group T below can be applied. Regarding each linking group in the water-soluble polymer (X), unless otherwise specified, the description of the linking group obtained by removing hydrogen bonds from the corresponding substituent in substituent group T below can be applied.
－　置換基群Ｔ　－
　アルキル基（好ましくは炭素数が１～２０であるアルキル基、例えばメチル、エチル、イソプロピル、ｔ－ブチル、ペンチル、ヘプチル、１－エチルペンチル、ベンジル、２－エトキシエチル、１－カルボキシメチル等）、アルケニル基（好ましくは炭素数が２～２０であるアルケニル基、例えば、ビニル、アリル、オレイル等）、アルキニル基（好ましくは炭素数が２～２０であるアルキニル基、例えば、エチニル、ブタジイニル、フェニルエチニル等）、シクロアルキル基（好ましくは炭素数が３～２０であるシクロアルキル基、例えば、シクロプロピル、シクロペンチル、シクロヘキシル、４－メチルシクロヘキシル等）、アリール基（好ましくは炭素数が６～２６であるアリール基、例えば、フェニル、１－ナフチル、４－メトキシフェニル、２－クロロフェニル、３－メチルフェニル等）、ヘテロ環基（好ましくは炭素数が２～２０であるヘテロ環基で、より好ましくは、酸素原子、硫黄原子及び窒素原子の少なくとも１種を環構成原子として有する５又は６員のヘテロ環基である。ヘテロ環基は芳香族ヘテロ環基及び脂肪族ヘテロ環基を含む。例えば、テトラヒドロピラン環基、テトラヒドロフラン環基、２－ピリジル、４－ピリジル、２－イミダゾリル、２－ベンゾイミダゾリル、２－チアゾリル、２－オキサゾリル等）、アルコキシ基（好ましくは炭素数が１～２０であるアルコキシ基、例えば、メトキシ、エトキシ、イソプロピルオキシ、ベンジルオキシ等）、アリールオキシ基（好ましくは炭素数が６～２６であるアリールオキシ基、例えば、フェノキシ、１－ナフチルオキシ、３－メチルフェノキシ、４－メトキシフェノキシ等）、ヘテロ環オキシ基（上記ヘテロ環基に－Ｏ－基が結合した基）、アルコキシカルボニル基（好ましくは炭素数が２～２０であるアルコキシカルボニル基、例えば、エトキシカルボニル、２－エチルヘキシルオキシカルボニル等）、アリールオキシカルボニル基（好ましくは炭素数が７～２６であるアリールオキシカルボニル基、例えば、フェノキシカルボニル、１－ナフチルオキシカルボニル、３－メチルフェノキシカルボニル、４－メトキシフェノキシカルボニル等）、アミノ基（好ましくは炭素数が０～２０であるアミノ基であり、アルキル基及びアリール基から選択される基で置換されたアミノ基を含む。例えば、アミノ（－ＮＨ２）、Ｎ，Ｎ－ジメチルアミノ、Ｎ，Ｎ－ジエチルアミノ、Ｎ－エチルアミノ、アニリノ等）、スルファモイル基（好ましくは炭素数が０～２０であるスルファモイル基であり、アルキル基及びアリール基から選択される基で置換されたスルファモイル基を含む。例えば、スルファモイル（－ＳＯ２ＮＨ２）、Ｎ，Ｎ－ジメチルスルファモイル、Ｎ－フェニルスルファモイル等）、アシル基（アルキルカルボニル基、アルケニルカルボニル基、アルキニルカルボニル基、アリールカルボニル基及びヘテロ環カルボニル基を含み、好ましくは炭素数が１～２０であるアシル基、例えば、ホルミル、アセチル、プロピオニル、ブチリル、オクタノイル、ヘキサデカノイル、アクリロイル、メタクリロイル、クロトノイル、ベンゾイル、ナフトイル、ニコチノイル等）、アシルオキシ基（アルキルカルボニルオキシ基、アルケニルカルボニルオキシ基、アルキニルカルボニルオキシ基、アリールカルボニルオキシ基及びヘテロ環カルボニルオキシ基を含み、好ましくは炭素数が１～２０であるアシルオキシ基、例えば、ホルミルオキシ、アセチルオキシ、プロピオニルオキシ、ブチリルオキシ、オクタノイルオキシ、ヘキサデカノイルオキシ、アクリロイルオキシ、メタクリロイルオキシ、クロトノイルオキシ、ベンゾイルオキシ、ナフトイルオキシ、ニコチノイルオキシ等）、カルバモイル基（好ましくは炭素数が１～２０であるカルバモイル基であり、アルキル基及びアリール基から選択される基で置換されたカルバモイル基を含む。例えば、Ｎ，Ｎ－ジメチルカルバモイル、Ｎ－フェニルカルバモイル等）、アシルアミノ基（好ましくは炭素数が１～２０であるアシルアミノ基であり、アシルアミノ基におけるアシル基としては、上記アシル基が好ましく挙げられる。例えば、アセチルアミノ、ベンゾイルアミノ等）、アルキルチオ基（好ましくは炭素数が１～２０であるアルキルチオ基、例えば、メチルチオ、エチルチオ、イソプロピルチオ、ベンジルチオ等）、アリールチオ基（好ましくは炭素数が６～２６であるアリールチオ基、例えば、フェニルチオ、１－ナフチルチオ、３－メチルフェニルチオ、４－メトキシフェニルチオ等）、アリールシリル基（好ましくは炭素数が６～４２であるアリールシリル基、例えば、トリフェニルシリル等）、ヘテロ環チオ基（上記ヘテロ環基に－Ｓ－基が結合した基）、アルキルスルホニル基（好ましくは炭素数が１～２０であるアルキルスルホニル基、例えば、メチルスルホニル、エチルスルホニル等）、アリールスルホニル基（好ましくは炭素数が６～２２であるアリールスルホニル基、例えば、ベンゼンスルホニル等）、アルキルシリル基（好ましくは炭素数が１～２０であるアルキルシリル基、例えば、モノメチルシリル、ジメチルシリル、トリメチルシリル、トリエチルシリル等）、亜リン酸基（好ましくは炭素数が０～２０である亜リン酸基、例えば、－ＯＰ（＝Ｏ）（－ＯＨ）（ＲＰ））、次亜リン酸基（好ましくは炭素数が０～２０である次亜リン酸基、例えば、－ＯＰ（＝Ｏ）（ＲＰ）２）、ホスホリル基（好ましくは炭素数が０～２０であるホスホリル基、例えば、－Ｐ（＝Ｏ）（ＲＰ）２）、ホスフィニル基（好ましくは炭素数が０～２０であるホスフィニル基、例えば、－Ｐ（ＲＰ）２）、スルホ基、リン酸基、ホスホン酸基、カルボキシ基、ヒドロキシ基、スルファニル基、シアノ基、ハロゲン原子（例えばフッ素原子、塩素原子、臭素原子、ヨウ素原子）が挙げられる。ＲＰは、水素原子又は置換基（好ましくは置換基群Ｔから選択される基）である。
　また、これらの置換基群Ｔで挙げた各基は、上記置換基群Ｔで挙げた各基を更に置換基として有していてもよい。 - Substituent group T -
Alkyl group (preferably an alkyl group having 1 to 20 carbon atoms, such as methyl, ethyl, isopropyl, t-butyl, pentyl, heptyl, 1-ethylpentyl, benzyl, 2-ethoxyethyl, 1-carboxymethyl, etc.), Alkenyl group (preferably an alkenyl group having 2 to 20 carbon atoms, such as vinyl, allyl, oleyl, etc.), alkynyl group (preferably an alkynyl group having 2 to 20 carbon atoms, such as ethynyl, butadiynyl, phenylethynyl) ), cycloalkyl groups (preferably cycloalkyl groups having 3 to 20 carbon atoms, such as cyclopropyl, cyclopentyl, cyclohexyl, 4-methylcyclohexyl, etc.), aryl groups (preferably having 6 to 26 carbon atoms) Aryl groups (for example, phenyl, 1-naphthyl, 4-methoxyphenyl, 2-chlorophenyl, 3-methylphenyl, etc.), heterocyclic groups (preferably heterocyclic groups having 2 to 20 carbon atoms, more preferably, A 5- or 6-membered heterocyclic group having at least one of an oxygen atom, a sulfur atom, and a nitrogen atom as a ring constituent atom.Heterocyclic groups include aromatic heterocyclic groups and aliphatic heterocyclic groups.For example, tetrahydro pyran ring group, tetrahydrofuran ring group, 2-pyridyl, 4-pyridyl, 2-imidazolyl, 2-benzimidazolyl, 2-thiazolyl, 2-oxazolyl, etc.), alkoxy group (preferably an alkoxy group having 1 to 20 carbon atoms, For example, methoxy, ethoxy, isopropyloxy, benzyloxy, etc.), aryloxy groups (preferably aryloxy groups having 6 to 26 carbon atoms, such as phenoxy, 1-naphthyloxy, 3-methylphenoxy, 4-methoxyphenoxy) etc.), heterocyclic oxy groups (groups in which -O- group is bonded to the above heterocyclic group), alkoxycarbonyl groups (preferably alkoxycarbonyl groups having 2 to 20 carbon atoms, such as ethoxycarbonyl, 2-ethylhexyloxy carbonyl, etc.), aryloxycarbonyl group (preferably an aryloxycarbonyl group having 7 to 26 carbon atoms, such as phenoxycarbonyl, 1-naphthyloxycarbonyl, 3-methylphenoxycarbonyl, 4-methoxyphenoxycarbonyl, etc.), amino group (preferably an amino group having 0 to 20 carbon atoms, including an amino group substituted with a group selected from an alkyl group and an aryl group. For example, amino (-NH 2 ), N,N-dimethyl amino, N,N-diethylamino, N-ethylamino, anilino, etc.), sulfamoyl group (preferably a sulfamoyl group having 0 to 20 carbon atoms, substituted with a group selected from alkyl groups and aryl groups) Contains groups. For example, sulfamoyl (-SO 2 NH 2 ), N,N-dimethylsulfamoyl, N-phenylsulfamoyl, etc.), acyl groups (alkylcarbonyl group, alkenylcarbonyl group, alkynylcarbonyl group, arylcarbonyl group, and heterocycle) Acyl group containing a carbonyl group and preferably having 1 to 20 carbon atoms, such as formyl, acetyl, propionyl, butyryl, octanoyl, hexadecanoyl, acryloyl, methacryloyl, crotonoyl, benzoyl, naphthoyl, nicotinoyl, etc.), acyloxy group (Including alkylcarbonyloxy groups, alkenylcarbonyloxy groups, alkynylcarbonyloxy groups, arylcarbonyloxy groups and heterocyclic carbonyloxy groups, preferably acyloxy groups having 1 to 20 carbon atoms, such as formyloxy, acetyloxy, propionyloxy, butyryloxy, octanoyloxy, hexadecanoyloxy, acryloyloxy, methacryloyloxy, crotonoyloxy, benzoyloxy, naphthoyloxy, nicotinoyloxy, etc.), carbamoyl group (preferably has 1 to 20 carbon atoms) It is a carbamoyl group, and includes a carbamoyl group substituted with a group selected from an alkyl group and an aryl group.For example, N,N-dimethylcarbamoyl, N-phenylcarbamoyl, etc.), an acylamino group (preferably having 1 to 1 carbon atoms), and a carbamoyl group substituted with a group selected from alkyl groups and aryl groups. 20, and the acyl group in the acylamino group is preferably the above-mentioned acyl group.For example, acetylamino, benzoylamino, etc.), an alkylthio group (preferably an alkylthio group having 1 to 20 carbon atoms, For example, methylthio, ethylthio, isopropylthio, benzylthio, etc.), arylthio group (preferably an arylthio group having 6 to 26 carbon atoms, such as phenylthio, 1-naphthylthio, 3-methylphenylthio, 4-methoxyphenylthio, etc.) , an arylsilyl group (preferably an arylsilyl group having 6 to 42 carbon atoms, such as triphenylsilyl), a heterocyclic thio group (a group in which an -S- group is bonded to the above heterocyclic group), an alkylsulfonyl group (preferably an alkylsulfonyl group having 1 to 20 carbon atoms, such as methylsulfonyl, ethylsulfonyl, etc.), an arylsulfonyl group (preferably an arylsulfonyl group having 6 to 22 carbon atoms, such as benzenesulfonyl), Alkylsilyl group (preferably alkylsilyl group having 1 to 20 carbon atoms, such as monomethylsilyl, dimethylsilyl, trimethylsilyl, triethylsilyl, etc.), phosphorous group (preferably phosphorous group having 0 to 20 carbon atoms) Acid groups, such as -OP(=O)(-OH)(R P )), hypophosphorous acid groups (preferably hypophosphorous acid groups having 0 to 20 carbon atoms, such as -OP(=O )(R P ) 2 ), phosphoryl group (preferably a phosphoryl group having 0 to 20 carbon atoms, such as -P(=O)(R P ) 2 ), phosphinyl group (preferably having 0 to 20 carbon atoms) A phosphinyl group, such as -P(R P ) 2 ), a sulfo group, a phosphoric acid group, a phosphonic acid group, a carboxy group, a hydroxy group, a sulfanyl group, a cyano group, a halogen atom (such as a fluorine atom, a chlorine atom, a bromine atom) atoms, iodine atoms). R P is a hydrogen atom or a substituent (preferably a group selected from substituent group T).
Moreover, each group listed in these substituent group T may further have each group listed in the above-mentioned substituent group T as a substituent.
　本発明に用いられる水溶性高分子（Ｘ）は、通常のポリマーの合成方法により得ることができる。本発明に用いられる水溶性高分子（Ｘ）の合成において、連鎖重合等の方法及び条件は、特に限定されず、通常の方法及び条件を、目的に応じて適宜に適用することができる。
　なお、水溶性高分子（Ｘ）の「水溶性」は、例えば、構成成分の種類及びその含有量によって制御することができる。 The water-soluble polymer (X) used in the present invention can be obtained by a conventional polymer synthesis method. In the synthesis of the water-soluble polymer (X) used in the present invention, the methods and conditions for chain polymerization etc. are not particularly limited, and conventional methods and conditions can be appropriately applied depending on the purpose.
Note that the "water solubility" of the water-soluble polymer (X) can be controlled, for example, by the types of constituent components and their contents.
　本発明に用いる水溶性高分子（Ｘ）の好ましい具体例を以下に示すが、本発明はこれらに限定して解釈されるものではない。下記具体例において、ａ及びｂは各構成成分の割合（質量％）を示す。ａ＝９９～２０であって、ｂ＝１～８０であり、ａ＋ｂ＝１００である。 Preferred specific examples of the water-soluble polymer (X) used in the present invention are shown below, but the present invention is not to be interpreted as being limited to these. In the specific examples below, a and b indicate the proportion (% by mass) of each component. a=99-20, b=1-80, and a+b=100.
Figure JPOXMLDOC01-appb-C000005
Figure JPOXMLDOC01-appb-C000005
　本発明において、水溶性高分子（Ｘ）は１種単独で用いてもよく、２種以上を組み合わせて用いてもよい。 In the present invention, the water-soluble polymer (X) may be used alone or in combination of two or more.
（水溶性高分子（Ｙ））
　本発明において、水溶性高分子（Ｙ）は、上述の水溶性高分子（Ｘ）とは構造の異なる水溶性高分子であり、二次電池の電極活物質層形成用スラリーの増粘剤として機能するものを広く用いることができる。上記増粘剤としては、増粘剤として機能する多糖類が挙げられ、天然多糖類及び合成多糖類のいずれでもよく、以下の例が挙げられる。
　増粘多糖類であるセルロース化合物としては、例えばメチルセルロース、エチルセルロース、ベンジルセルロース、トリエチルセルロース、シアノエチルセルロース、ニトロセルロース、ヒドロキシメチルセルロース、ヒドロキシエチルセルロース（ＨＥＣ）、ヒドロキシプロピルセルロース（ＨＰＣ）、ヒドロキシプロピルメチルセルロース（ＨＰＭＣ）、ヒドロキシブチルメチルセルロース、カルボキシメチルセルロース（ＣＭＣ）、アミノメチルヒドロキシプロピルセルロース、アミノエチルヒドロキシプロピルセルロース、セルロースナノファイバー（ＣＮＦ）、セルロースナノクリスタル（ＣＮＣ）等が挙げられる。また、セルロース化合物は、アンモニウム塩、ナトリウム塩、リチウム塩等の塩の態様であってもよい。
　セルロース化合物において、エーテル置換度は通常０．５～１．５であればよく、０．５～１．０が好ましい。なお、エーテル置換度とは、セルロースのグルコース環単位当たり、エーテル基で置換された水酸基の平均個数を意味し、滴定などにより測定することができる。
　また、上記セルロース化合物以外の天然多糖類としては、例えばカラギナン、キサンタンガム、グァーガム、タマリンドガム（タマリンドシードガム）、ダイユータンガム、ウェランガム、ジェランガム、ローカストビーンガム、タラガム等が挙げられる。
　これらの中でも、水溶性高分子（Ｙ）は、カルボキシメチルセルロース（ＣＭＣ）、ヒドロキシエチルセルロース（ＨＥＣ）、ヒドロキシプロピルセルロース（ＨＰＣ）、ヒドロキシプロピルメチルセルロース（ＨＰＭＣ）、カラギナン及びキサンタンガムの少なくとも１種を含むことが好ましく、サイクル特性をより向上させる観点から、カルボキシメチルセルロース、ヒドロキシエチルセルロース、ヒドロキシプロピルセルロース及びキサンタンガムの少なくとも１種を含むことがより好ましい。 (Water-soluble polymer (Y))
In the present invention, the water-soluble polymer (Y) is a water-soluble polymer having a different structure from the water-soluble polymer (X) described above, and is used as a thickener for a slurry for forming an electrode active material layer of a secondary battery. A wide variety of functional materials can be used. Examples of the above-mentioned thickener include polysaccharides that function as thickeners, and may be either natural polysaccharides or synthetic polysaccharides, and examples include the following.
Examples of cellulose compounds that are polysaccharide thickeners include methylcellulose, ethylcellulose, benzylcellulose, triethylcellulose, cyanoethylcellulose, nitrocellulose, hydroxymethylcellulose, hydroxyethylcellulose (HEC), hydroxypropylcellulose (HPC), and hydroxypropylmethylcellulose (HPMC). , hydroxybutylmethylcellulose, carboxymethylcellulose (CMC), aminomethylhydroxypropylcellulose, aminoethylhydroxypropylcellulose, cellulose nanofiber (CNF), cellulose nanocrystal (CNC), and the like. Further, the cellulose compound may be in the form of a salt such as an ammonium salt, a sodium salt, or a lithium salt.
In the cellulose compound, the degree of ether substitution may normally be from 0.5 to 1.5, preferably from 0.5 to 1.0. The degree of ether substitution means the average number of hydroxyl groups substituted with ether groups per glucose ring unit of cellulose, and can be measured by titration or the like.
Examples of natural polysaccharides other than the cellulose compounds include carrageenan, xanthan gum, guar gum, tamarind gum (tamarind seed gum), diutan gum, welan gum, gellan gum, locust bean gum, and tara gum.
Among these, the water-soluble polymer (Y) may include at least one of carboxymethylcellulose (CMC), hydroxyethylcellulose (HEC), hydroxypropylcellulose (HPC), hydroxypropylmethylcellulose (HPMC), carrageenan, and xanthan gum. Preferably, from the viewpoint of further improving cycle characteristics, it is more preferable that at least one of carboxymethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, and xanthan gum is included.
　本発明に用いられる水溶性高分子（Ｙ）の重量平均分子量（Ｍｗ）は特に制限されず、例えば、１０００００～５０００００が好ましく、１５００００～５０００００がより好ましく、２０００００～５０００００がさらに好ましい。 The weight average molecular weight (Mw) of the water-soluble polymer (Y) used in the present invention is not particularly limited, and is preferably, for example, 100,000 to 500,000, more preferably 150,000 to 500,000, and even more preferably 200,000 to 500,000.
（重量平均分子量の測定）
　本発明において、水溶性高分子（Ｙ）の重量平均分子量については、前述の水溶性高分子（Ｘ）に記載の方法により測定される値である。 (Measurement of weight average molecular weight)
In the present invention, the weight average molecular weight of the water-soluble polymer (Y) is a value measured by the method described in the above-mentioned water-soluble polymer (X).
　本発明において、水溶性高分子（Ｙ）は１種単独で用いてもよく、２種以上を組み合わせて用いてもよい。 In the present invention, the water-soluble polymer (Y) may be used alone or in combination of two or more.
（重合体粒子）
　本発明のバインダー組成物は、サイクル特性をより向上させる観点から重合体粒子を含有することも好ましい。
　含有していてもよい重合体粒子は粒子状のポリマーであり、「粒子状」は、偏平状、無定形等であってもよく、球状若しくは顆粒状が好ましい。
　なお、重合体粒子は非水溶性高分子の粒子である。すなわち、重合体粒子は２０℃において水に対する溶解度が１０ｇ／Ｌ－Ｈ２Ｏ未満である（水１リットルに対して１０ｇ以上溶解しない）ポリマーの粒子である。 (polymer particles)
It is also preferable that the binder composition of the present invention contains polymer particles from the viewpoint of further improving cycle characteristics.
The polymer particles that may be contained are particulate polymers, and "particulate" may be flat, amorphous, etc., and preferably spherical or granular.
Note that the polymer particles are particles of a water-insoluble polymer. That is, the polymer particles are particles of a polymer whose solubility in water at 20° C. is less than 10 g/L-H 2 O (not more than 10 g per liter of water).
　重合体粒子の引張弾性率は、サイクル特性を向上させる観点から、１００～３０００ＭＰａが好ましく、１００～１０００ＭＰａがより好ましい。本発明において、上記引張弾性率は後記実施例に記載のバインダー組成物の引張弾性率の算出方法において、バインダー組成物に代えて重合体粒子の水溶液を用いて試験片を作製する以外は同様にして決定することができる。 The tensile modulus of the polymer particles is preferably 100 to 3000 MPa, more preferably 100 to 1000 MPa, from the viewpoint of improving cycle characteristics. In the present invention, the above tensile modulus is calculated in the same manner as in the method for calculating the tensile modulus of a binder composition described in Examples below, except that a test piece is prepared using an aqueous solution of polymer particles instead of the binder composition. It can be determined by
　重合体粒子のガラス転移温度は特に制限されず、電極シートの密着性及びサイクル特性向上の観点から、－５０～１５０℃が好ましく、－３０～１００℃がより好ましく、０～１００℃がさらに好ましい。
　なお、重合体粒子がガラス転移温度を２点以上有する場合には、その全てが上記好ましい範囲内に入ることが好ましい。 The glass transition temperature of the polymer particles is not particularly limited, and from the viewpoint of improving the adhesion and cycle characteristics of the electrode sheet, it is preferably -50 to 150 °C, more preferably -30 to 100 °C, and even more preferably 0 to 100 °C. .
In addition, when a polymer particle has two or more glass transition temperatures, it is preferable that all of them fall within the above-mentioned preferable range.
―ガラス転移温度―
　市販品の重合体粒子を用いる場合、重合体粒子のガラス転移温度は製造元のカタログ記載の値を採用する。
　製造元のガラス転移温度の情報が入手できない場合又は合成した重合体粒子を用いる場合は、文献ＰＯＬＹＭＥＲ　ＨＡＮＤＢＯＯＫ　４ｔｈ、３６章の表のガラス転移温度の値を採用する。上記文献にガラス転移温度が記載されていない場合は下記測定条件で測定して得られるガラス転移温度の値を採用する。 -Glass-transition temperature-
When using commercially available polymer particles, the glass transition temperature of the polymer particles is the value listed in the manufacturer's catalog.
When the manufacturer's glass transition temperature information is not available or when using synthesized polymer particles, the glass transition temperature values in the table in Chapter 36 of the literature POLYMER HANDBOOK 4th are adopted. When the glass transition temperature is not described in the above literature, the value of the glass transition temperature obtained by measurement under the following measurement conditions is adopted.
　ガラス転移温度（Ｔｇ）は、重合体粒子の乾燥試料を用いて、示差走査熱量計：Ｘ－ＤＳＣ７０００（商品名、ＳＩＩ・ナノテクノロジー社製）を用いて下記測定条件で測定のうえ算出する。測定は同一の試料で二回実施し、二回目の測定結果を採用する。
（測定条件）
　　測定室内の雰囲気：窒素ガス（５０ｍＬ／ｍｉｎ）
　　昇温速度：５℃／ｍｉｎ
　　測定開始温度：－８０℃
　　測定終了温度：２５０℃
　　試料パン：アルミニウム製パン
　　測定試料の質量：５ｍｇ
　　Ｔｇの算出：ＤＳＣ（示差走査熱量測定）チャートの下降開始点と下降終了点の中間温度の小数点以下を四捨五入することでＴｇを算出する。 The glass transition temperature (Tg) is calculated by measuring a dry sample of polymer particles using a differential scanning calorimeter: X-DSC7000 (trade name, manufactured by SII Nano Technology Co., Ltd.) under the following measurement conditions. Measurements are performed twice on the same sample, and the results of the second measurement are used.
(Measurement condition)
Atmosphere in the measurement chamber: Nitrogen gas (50mL/min)
Temperature increase rate: 5℃/min
Measurement start temperature: -80℃
Measurement end temperature: 250℃
Sample pan: Aluminum pan Mass of measurement sample: 5 mg
Calculation of Tg: Tg is calculated by rounding off the decimal point of the intermediate temperature between the start point and end point of the drop on the DSC (differential scanning calorimetry) chart.
　重合体粒子の平均粒径（水中での体積基準のメジアン径）は、特に制限されず、５０～３００ｎｍが好ましく、５０～２５０ｎｍがより好ましく、５０～２００ｎｍが更に好ましい。
　市販品の重合体粒子を用いる場合、重合体粒子の平均粒径は製造元のカタログ記載の値を採用する。
　製造元の平均粒径の情報が入手できない場合又は合成した重合体粒子を用いる場合は、重合体粒子の平均粒径は、レーザー回折・散乱法によって測定された粒度分布において小径側から計算した累積体積が５０％となる粒子径（水中での体積基準のメジアン径）である。 The average particle diameter (volume-based median diameter in water) of the polymer particles is not particularly limited, and is preferably from 50 to 300 nm, more preferably from 50 to 250 nm, even more preferably from 50 to 200 nm.
When using commercially available polymer particles, the average particle diameter of the polymer particles is the value listed in the manufacturer's catalog.
If the manufacturer's average particle size information is not available or if synthesized polymer particles are used, the average particle size of the polymer particles is the cumulative volume calculated from the small diameter side in the particle size distribution measured by laser diffraction/scattering method. is the particle diameter (median diameter on a volume basis in water) at which 50% is obtained.
　重合体粒子は逐次重合ポリマー粒子及び連鎖重合ポリマー粒子のいずれでもよく、連鎖重合ポリマー粒子が好ましい。連鎖重合ポリマー粒子は、ホモポリマーでもよく、コポリマーでもよい。コポリマーの重合形態はランダム及びブロックのいずれでもよい。
　重合体粒子（連鎖重合ポリマー）の構成成分としては、例えば、共役ジエン成分、芳香族ビニルモノマー成分、エチレン性不飽和カルボン酸成分、シアノ基含有エチレン性モノマー成分、エチレン性不飽和カルボン酸エステル成分及びフッ化ビニルモノマー成分が挙げられ、共役ジエン成分、エチレン性不飽和カルボン酸成分、シアノ基含有エチレン性モノマー成分及び芳香族ビニルモノマー成分の少なくとも１種を含むことが好ましい。重合体粒子は、上記構成成分の中でも共役ジエン成分及び芳香族ビニルモノマー成分を有することが好ましい。
　上記において、芳香族ビニルモノマー成分とは、炭素－炭素二重結合（好ましくは１つ又は２つ、より好ましくは１つ）とアリール基（好ましくは１つ）とを有するモノマー由来の成分を意味し、エチレン性不飽和カルボン酸成分とは、炭素－炭素二重結合（好ましくは１つ）とカルボキシ基（好ましくは１つ又は２つ）とを有するモノマー由来の成分を意味し、シアノ基含有エチレン性モノマー成分とは、炭素－炭素二重結合（好ましくは１つ）とシアノ基（好ましくは１つ又は２つ、より好ましくは１つ）とを有するモノマー由来の成分を意味し、エチレン性不飽和カルボン酸エステル成分とは、炭素－炭素二重結合（好ましくは１つ）とカルボン酸エステル部位（エステル化されたカルボキシ基）（好ましくは１つ）とを有するモノマー由来の成分を意味し、フッ化ビニルモノマー成分とは、１～４個（好ましくは２個）のフッ素原子を有するエチレン由来の成分を意味する。
　なお、上記「炭素－炭素二重結合」には、芳香族環の炭素－炭素二重結合は含まれない。 The polymer particles may be either sequential polymer particles or chain polymer particles, and chain polymer particles are preferred. The chain polymer particles may be homopolymers or copolymers. The polymerization form of the copolymer may be either random or block.
Constituent components of the polymer particles (chain polymerization polymer) include, for example, a conjugated diene component, an aromatic vinyl monomer component, an ethylenically unsaturated carboxylic acid component, a cyano group-containing ethylenic monomer component, and an ethylenically unsaturated carboxylic acid ester component. and a fluorinated vinyl monomer component, and preferably contains at least one of a conjugated diene component, an ethylenically unsaturated carboxylic acid component, a cyano group-containing ethylenic monomer component, and an aromatic vinyl monomer component. It is preferable that the polymer particles have a conjugated diene component and an aromatic vinyl monomer component among the above components.
In the above, the aromatic vinyl monomer component means a component derived from a monomer having a carbon-carbon double bond (preferably one or two, more preferably one) and an aryl group (preferably one). However, the ethylenically unsaturated carboxylic acid component means a component derived from a monomer having a carbon-carbon double bond (preferably one) and a carboxy group (preferably one or two), and contains a cyano group. The ethylenic monomer component means a component derived from a monomer having a carbon-carbon double bond (preferably one) and a cyano group (preferably one or two, more preferably one); The unsaturated carboxylic acid ester component means a component derived from a monomer having a carbon-carbon double bond (preferably one) and a carboxylic acid ester moiety (esterified carboxy group) (preferably one). The fluorinated vinyl monomer component means an ethylene-derived component having 1 to 4 (preferably 2) fluorine atoms.
Note that the above-mentioned "carbon-carbon double bond" does not include the carbon-carbon double bond of an aromatic ring.
　共役ジエン成分を導く共役ジエンとしては、例えば、１，３－ブタジエン、２－メチル－１，３－ブタジエン（イソプレン）、２，３－ジメチル－１，３－ブタジエン及び２－クロロ－１，３－ブタジエン等の脂肪族共役ジエンが挙げられる。
　芳香族ビニルモノマー成分を導く芳香族ビニルモノマーとしては、例えば、スチレン、α－メチルスチレン、４－ｔｅｒｔ－ブチルスチレン、４－ｔｅｒｔ－ブトキシスチレン、ビニルトルエン（３－ビニルトルエン、４－ビニルトルエン）及びジビニルベンゼン（ｍ－ジビニルベンゼン、ｐ－ジビニルベンゼン）が挙げられる。
　エチレン性不飽和カルボン酸成分を導くエチレン性不飽和カルボン酸としては、例えば、（メタ）アクリル酸、マレイン酸、イタコン酸及びフマル酸が挙げられる。
　シアノ基含有エチレン性モノマー成分を導くシアノ基含有エチレン性モノマーとしては、例えば、（メタ）アクリロニトリル、α－クロロアクリロニトリル、α－エチルアクリロニトリル及びシアン化ビニリデンが挙げられる。
　エチレン性不飽和カルボン酸エステル成分を導くエチレン性不飽和カルボン酸エステルとしては、例えば、（メタ）アクリル酸メチル、（メタ）アクリル酸エチル、（メタ）アクリル酸プロピル、（メタ）アクリル酸ブチル、（メタ）アクリル酸ヘキシル、（メタ）アクリル酸オクチル、２－エチルヘキシル（メタ）アクリレート、２－ヒドロキシエチル（メタ）アクリレート、エチレングリコールジ（メタ）アクリレート及び２，２，２－トリフルオロエチル（メタ）アクリレート等の（メタ）アクリル酸アルキルエステルが挙げられる。
　フッ化ビニルモノマー成分を導くフッ化ビニルモノマーとしては、例えば、フッ化ビニリデンが挙げられる。 Examples of the conjugated diene leading to the conjugated diene component include 1,3-butadiene, 2-methyl-1,3-butadiene (isoprene), 2,3-dimethyl-1,3-butadiene, and 2-chloro-1,3 - Aliphatic conjugated dienes such as butadiene.
Examples of the aromatic vinyl monomer leading to the aromatic vinyl monomer component include styrene, α-methylstyrene, 4-tert-butylstyrene, 4-tert-butoxystyrene, and vinyltoluene (3-vinyltoluene, 4-vinyltoluene). and divinylbenzene (m-divinylbenzene, p-divinylbenzene).
Examples of the ethylenically unsaturated carboxylic acid leading to the ethylenically unsaturated carboxylic acid component include (meth)acrylic acid, maleic acid, itaconic acid, and fumaric acid.
Examples of the cyano group-containing ethylenic monomer leading to the cyano group-containing ethylenic monomer component include (meth)acrylonitrile, α-chloroacrylonitrile, α-ethyl acrylonitrile, and vinylidene cyanide.
Examples of the ethylenically unsaturated carboxylic ester that leads to the ethylenically unsaturated carboxylic ester component include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, Hexyl (meth)acrylate, octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, ethylene glycol di(meth)acrylate and 2,2,2-trifluoroethyl (meth)acrylate. ) (meth)acrylic acid alkyl esters such as acrylate.
Examples of the vinyl fluoride monomer leading to the vinyl fluoride monomer component include vinylidene fluoride.
　本発明に用いられる重合体粒子は、通常のポリマーの合成方法により得ることができる。本発明に用いられる重合体粒子の合成において、連鎖重合等の方法及び条件は、特に限定されず、通常の方法及び条件を、目的に応じて適宜に適用することができる。
　また、重合体粒子は、上述の逐次重合ポリマー粒子及び連鎖重合ポリマー粒子について、カルボキシ変性等の変性処理を行った粒子でもよい。変性処理の方法及び条件は、特に限定されず、常法により行うことができる。
　重合体粒子の水に対する溶解度、引張弾性率、ガラス転移温度及び平均粒径は、例えば、ポリマー中の構成成分の種類及び含有量により調整できる。 The polymer particles used in the present invention can be obtained by conventional polymer synthesis methods. In the synthesis of the polymer particles used in the present invention, the methods and conditions for chain polymerization etc. are not particularly limited, and conventional methods and conditions can be appropriately applied depending on the purpose.
Further, the polymer particles may be particles obtained by performing a modification treatment such as carboxy modification on the above-mentioned sequential polymer particles and chain polymer particles. The method and conditions for the modification treatment are not particularly limited, and can be carried out by conventional methods.
The water solubility, tensile modulus, glass transition temperature, and average particle size of the polymer particles can be adjusted, for example, by adjusting the types and contents of the constituent components in the polymer.
　重合体粒子の具体例としては、スチレン／ブタジエンコポリマー、アクリルポリマー及びポリ（フッ化ビニリデン）が挙げられ、スチレン／ブタジエンコポリマーが好ましい。
　スチレン／ブタジエンコポリマーとは、上記芳香族ビニルモノマー成分及び上記共役ジエン成分を有する共重合体を意味し、カルボキシ変性等の変性共重合体であってもよい。
　アクリルポリマーとは、上記エチレン性不飽和カルボン酸成分及び／又は上記エチレン性不飽和カルボン酸エステル成分を含有する重合体を意味する。
　スチレン／ブタジエンコポリマーとしては、例えば、国際公開第２０２１／１７２２０８号、国際公開第２０２１／１５３５１６号、国際公開第２０２１／０６５４５７号、国際公開第２０１９／１８８７２２号、国際公開第２０１８／１７３７１７号、国際公開第２０１７／０５６４６６号、国際公開第２０１４／１４１７２１号、特開２０１４－２０３７７１号公報、国際公開第２０１３／１４１１４０号、特開２０１４－１１６２６３号公報、特開２００３－１５１５６０号公報、特開２０００－１２３８３８号公報、特開２０００－１００４３６号公報、国際公開第１９９９／０４８９５３号、国際公開第２０２０／２２６０３５号、国際公開第２０１４／０５７７４９号、特開２０１９－１７９６３１号公報、特開２０１７－１２６４５６号公報、特開２０１７－０８４６２１号公報、特開２０１５－１９１８７６号公報、特開２０１２－１６９１１２号公報、特開２０１２－０９４５０６号公報、特開２０１１－１０８３７３号公報、特開２０１０－２０５７２２号公報又は特開２０１０－１４０６８４号公報に記載のものを用いることができる。
　アクリルポリマーとしては、例えば、特開２０２０－１２３５９０号公報、国際公開第２０１８／１７３７１７号、特開２０１６－０２４９８５号公報、国際公開第２０１５／１０７８９６号、国際公開第２０１４／１４８０６４号、国際公開第２０１４／０７３６４７号、特開２０１４－２０３８０５号公報、特開２０１４－１１６２６５号公報、特開２０１５－１０６４８８号公報、国際公開第２０１８／１９４１０１号、国際公開第２０１５／０１２３６６号、国際公開第２０１２／０４９９７１号、特開２０１２－２１２５３７号公報、特開２０１１－１７１１８１号公報、特開２０１０－２４５０３５号公報、特開２０１０－１９２４３４号公報、特開２０１０－１８２４３９号公報、特開２０１０－１４６８７０号公報、特開２０１０－１４６８６９号公報又は特開２００２－３１９４０３号公報に記載のものを用いることができる。
　ポリ（フッ化ビニリデン）としては、例えば、特開２０１４－２２９４０６号公報、国際公開第２０１３／００５７９６号、国際公開第２０１１／０４０４７４号、国際公開第２００９／１２３１６８号、国際公開第２０１４／０５７７４９号又は国際公開第２０１２／１１７９１０号に記載のものを用いることができる。
　他にも、例えば国際公開第２０１３／００５７９６号の段落番号０１２０～０１２３に記載のものを用いることができる。 Specific examples of polymer particles include styrene/butadiene copolymers, acrylic polymers, and poly(vinylidene fluoride), with styrene/butadiene copolymers being preferred.
The styrene/butadiene copolymer means a copolymer having the above-mentioned aromatic vinyl monomer component and the above-mentioned conjugated diene component, and may be a modified copolymer such as a carboxy-modified copolymer.
The acrylic polymer means a polymer containing the ethylenically unsaturated carboxylic acid component and/or the ethylenically unsaturated carboxylic acid ester component.
Examples of the styrene/butadiene copolymer include WO 2021/172208, WO 2021/153516, WO 2021/065457, WO 2019/188722, WO 2018/173717, Publication No. 2017/056466, International Publication No. 2014/141721, JP 2014-203771, WO 2013/141140, JP 2014-116263, JP 2003-151560, JP 2000 -123838, JP 2000-100436, WO 1999/048953, WO 2020/226035, WO 2014/057749, JP 2019-179631, JP 2017-126456 No. 2017-084621, 2015-191876, 2012-169112, 2012-094506, 2011-108373, 2010-205722 Alternatively, the one described in JP-A No. 2010-140684 can be used.
Examples of the acrylic polymer include JP 2020-123590 A, WO 2018/173717, JP 2016-024985, WO 2015/107896, WO 2014/148064, and WO 2014/148064. 2014/073647, JP 2014-203805, JP 2014-116265, JP 2015-106488, WO 2018/194101, WO 2015/012366, WO 2012/ 049971, JP 2012-212537, JP 2011-171181, JP 2010-245035, JP 2010-192434, JP 2010-182439, JP 2010-146870 , those described in JP-A-2010-146869 or JP-A-2002-319403 can be used.
Examples of poly(vinylidene fluoride) include JP2014-229406A, WO2013/005796, WO2011/040474, WO2009/123168, and WO2014/057749. Alternatively, the one described in International Publication No. 2012/117910 can be used.
In addition, for example, those described in paragraph numbers 0120 to 0123 of International Publication No. 2013/005796 can be used.
　本発明において、重合体粒子は１種単独で用いてもよく、２種以上を組み合わせて用いてもよい。 In the present invention, one type of polymer particles may be used alone, or two or more types may be used in combination.
　本発明のバインダー組成物は、水溶性高分子（Ｘ）及び水溶性高分子（Ｙ）、並びに、含有していてもよい重合体粒子以外に、電池用のバインダーとして常用されるその他のポリマーを含有していてもよい。
　本発明のバインダー組成物に含有される、水溶性高分子（Ｘ）、水溶性高分子（Ｙ）及びその他のポリマーの合計に占める、水溶性高分子（Ｘ）及び水溶性高分子（Ｙ）の割合は、合計で８０質量％以上が好ましく、９０質量％以上がより好ましく、９５質量％以上が更に好ましく、９９質量％以上が特に好ましく、１００質量％であることが最も好ましい。
　本発明のバインダー組成物中、水溶性高分子（Ｘ）と水溶性高分子（Ｙ）との質量比（水溶性高分子（Ｘ）の質量：水溶性高分子（Ｙ）の質量）は特に制限されず、２０～９０：１０～８０が好ましく、４０～８０：２０～６０がより好ましい。 The binder composition of the present invention contains, in addition to the water-soluble polymer (X), the water-soluble polymer (Y), and the polymer particles that may be contained, other polymers commonly used as binders for batteries. May contain.
Water-soluble polymer (X) and water-soluble polymer (Y) account for the total of water-soluble polymer (X), water-soluble polymer (Y), and other polymers contained in the binder composition of the present invention The total proportion is preferably 80% by mass or more, more preferably 90% by mass or more, even more preferably 95% by mass or more, particularly preferably 99% by mass or more, and most preferably 100% by mass.
In the binder composition of the present invention, the mass ratio of water-soluble polymer (X) to water-soluble polymer (Y) (mass of water-soluble polymer (X): mass of water-soluble polymer (Y)) is particularly There is no restriction, but 20-90:10-80 is preferable, and 40-80:20-60 is more preferable.
　本発明のバインダー組成物が重合体粒子を含有する場合、本発明のバインダー組成物に含有される、水溶性高分子（Ｘ）、水溶性高分子（Ｙ）、重合体粒子及びその他のポリマーの合計に占める、水溶性高分子（Ｘ）、水溶性高分子（Ｙ）及び重合体粒子の割合は、合計で８０質量％以上が好ましく、９０質量％以上がより好ましく、９５質量％以上が更に好ましく、９９質量％以上が特に好ましく、１００質量％であることが最も好ましい。
　本発明のバインダー組成物中、水溶性高分子（Ｘ）と、水溶性高分子（Ｙ）と、重合体粒子との質量比（水溶性高分子（Ｘ）の質量：水溶性高分子（Ｙ）の質量：重合体粒子の質量）は特に制限されず、１０～８０：１０～８０：１０～５０が好ましく、２０～７０：１０～６０：２０～５０がより好ましい。 When the binder composition of the present invention contains polymer particles, the water-soluble polymer (X), water-soluble polymer (Y), polymer particles and other polymers contained in the binder composition of the present invention The proportion of the water-soluble polymer (X), the water-soluble polymer (Y), and the polymer particles in the total is preferably 80% by mass or more, more preferably 90% by mass or more, and even more preferably 95% by mass or more. It is preferably 99% by mass or more, particularly preferably 100% by mass.
In the binder composition of the present invention, the mass ratio of water-soluble polymer (X), water-soluble polymer (Y), and polymer particles (mass of water-soluble polymer (X): water-soluble polymer (Y) ): mass of polymer particles) is not particularly limited, and is preferably 10 to 80:10 to 80:10 to 50, more preferably 20 to 70:10 to 60:20 to 50.
　本発明のバインダー組成物は、液媒体として水を含有することが好ましい。
　本発明のバインダー組成物中の水の含有量は、特に制限されず、例えば、１０質量％以上とすることができ、好ましくは２０質量％以上、より好ましくは３０質量％以上、更に好ましくは４０質量％以上、特に好ましくは５０質量％以上とすることができる。本発明のバインダー組成物は、水を６０質量％以上含有してもよく、７０質量％以上含有してもよく、８０質量％以上含有してもよい。一方、本発明のバインダー組成物中の水の含有量は、９９．５質量％以下であることが実際的である。
　本発明のバインダー組成物は、水以外の液媒体を含有していてもよい。水以外の液媒体としては、例えば、水と混合したときに相分離せずに混じり合う有機溶媒（以下、水溶性有機溶媒と称す。）が挙げられ、Ｎ－メチルピロリドン、メタノール、エタノール、アセトン、テトラヒドロフラン等が好ましく挙げられる。 The binder composition of the present invention preferably contains water as a liquid medium.
The content of water in the binder composition of the present invention is not particularly limited, and can be, for example, 10% by mass or more, preferably 20% by mass or more, more preferably 30% by mass or more, still more preferably 40% by mass or more. It can be at least 50% by mass, particularly preferably at least 50% by mass. The binder composition of the present invention may contain water in an amount of 60% by mass or more, 70% by mass or more, or 80% by mass or more. On the other hand, it is practical for the content of water in the binder composition of the present invention to be 99.5% by mass or less.
The binder composition of the present invention may contain a liquid medium other than water. Examples of liquid media other than water include organic solvents that mix with water without phase separation (hereinafter referred to as water-soluble organic solvents), such as N-methylpyrrolidone, methanol, ethanol, and acetone. , tetrahydrofuran, etc. are preferably mentioned.
　本発明のバインダー組成物中、水溶性高分子（Ｘ）及び水溶性高分子（Ｙ）の含有量は目的に応じて適宜に設定すればよい。例えば、バインダー組成物中の水溶性高分子（Ｘ）及び水溶性高分子（Ｙ）の含有量を合計で０．５～５０質量％とすることができ、好ましくは５～３０質量％、より好ましくは５～２５質量％である。
　本発明のバインダー組成物中、水溶性高分子（Ｘ）及び水溶性高分子（Ｙ）、含有していてもよい重合体粒子の含有量は目的に応じて適宜に設定すればよい。例えば、バインダー組成物中の水溶性高分子（Ｘ）、水溶性高分子（Ｙ）及び重合体粒子の含有量を合計で０．５～５０質量％とすることができ、好ましくは５～３０質量％、より好ましくは１０～２０質量％である。
　本発明のバインダー組成物は、水溶性高分子（Ｘ）及び水溶性高分子（Ｙ）、含有していてもよい重合体粒子、水及び水以外の液媒体の他にも、目的に応じて他の成分を含有することができる。他の成分としては、例えば、多価アルコール（ヒドロキシ基を２つ以上有するアルコール）が挙げられる。
　また、本発明のバインダー組成物は、水溶性高分子（Ｘ）及び水溶性高分子（Ｙ）、含有していてもよい重合体粒子の各合成液を希釈する等により調製することもできる。そのため、本発明のバインダー組成物中には、水溶性高分子（Ｘ）及び水溶性高分子（Ｙ）、含有していてもよい重合体粒子の合成に使用した化合物又はその反応後の副生成物が含まれていてもよい。 In the binder composition of the present invention, the contents of the water-soluble polymer (X) and the water-soluble polymer (Y) may be appropriately set depending on the purpose. For example, the total content of water-soluble polymer (X) and water-soluble polymer (Y) in the binder composition can be 0.5 to 50% by mass, preferably 5 to 30% by mass, and more. Preferably it is 5 to 25% by mass.
In the binder composition of the present invention, the contents of the water-soluble polymer (X), the water-soluble polymer (Y), and the polymer particles that may be contained may be appropriately set depending on the purpose. For example, the total content of water-soluble polymer (X), water-soluble polymer (Y), and polymer particles in the binder composition can be 0.5 to 50% by mass, preferably 5 to 30% by mass. % by weight, more preferably 10-20% by weight.
The binder composition of the present invention can be used in addition to the water-soluble polymer (X), the water-soluble polymer (Y), the polymer particles that may be contained, water and a liquid medium other than water, depending on the purpose. It may contain other ingredients. Examples of other components include polyhydric alcohols (alcohols having two or more hydroxy groups).
Moreover, the binder composition of the present invention can also be prepared by diluting each synthetic solution of the water-soluble polymer (X), the water-soluble polymer (Y), and the polymer particles that may be contained. Therefore, in the binder composition of the present invention, the water-soluble polymer (X) and the water-soluble polymer (Y), the compound used in the synthesis of the polymer particles that may be contained, or the by-products after the reaction. It may contain things.
　本発明のバインダー組成物の引張弾性率は、サイクル特性を向上させる観点から、重合体粒子を含まない場合、３５００～１５０００ＭＰａが好ましく、４５００～１２０００ＭＰａがより好ましく、６０００～１００００ＭＰａが更に好ましく、重合体粒子を含む場合、１５００～６０００ＭＰａが好ましく、２０００～５０００ＭＰａがより好ましく、２５００～５０００ＭＰａが更に好ましい。
　本発明において、上記引張弾性率は後記実施例に記載のバインダー組成物の引張弾性率の算出方法により決定することができる。 From the viewpoint of improving cycle characteristics, the tensile modulus of the binder composition of the present invention is preferably 3,500 to 15,000 MPa, more preferably 4,500 to 12,000 MPa, even more preferably 6,000 to 10,000 MPa, when polymer particles are not included. When particles are included, the pressure is preferably 1,500 to 6,000 MPa, more preferably 2,000 to 5,000 MPa, and even more preferably 2,500 to 5,000 MPa.
In the present invention, the tensile modulus can be determined by the method for calculating the tensile modulus of a binder composition described in Examples below.
＜電極用組成物＞
　本発明のバインダー組成物は、その一形態として、上記水溶性高分子（Ｘ）及び上記水溶性高分子（Ｙ）、並びに、含有していてもよい上記重合体粒子及び水に加え、周期律表第１族又は第２族に属する金属のイオンの挿入放出が可能な活物質を含有し得る。本発明のバインダー組成物中に活物質を含有する場合を、特に本発明の電極用組成物と称す。本発明の電極用組成物は、必要に応じて更に導電助剤、他の添加剤を含むことができる。活物質は正極活物質でもよく、負極活物質でもよい。電極用組成物が正極活物質を含む場合、電極用組成物を、二次電池の正極活物質層形成用スラリーとして用いることができる。また、電極用組成物が負極活物質を含む場合、電極用組成物を負極活物質層形成用スラリーとして用いることができる。本発明のバインダー組成物は正極又は負極どちらの電極用組成物にも適用できるが、負極に用いることが好ましく、特にケイ素系活物質を含有する負極の電極用組成物に用いることが好ましい。
　上記活物質、導電助剤、他の添加剤としては、特に限定されるものではなく、二次電池に常用されるものから目的に応じて適宜選択して用いればよい。 <Composition for electrode>
As one form of the binder composition of the present invention, in addition to the water-soluble polymer (X), the water-soluble polymer (Y), the polymer particles that may be contained, and water, It may contain an active material capable of inserting and releasing metal ions belonging to Group 1 or Group 2 in the table. The case where the active material is contained in the binder composition of the present invention is particularly referred to as the electrode composition of the present invention. The electrode composition of the present invention may further contain a conductive additive and other additives, if necessary. The active material may be a positive electrode active material or a negative electrode active material. When the electrode composition includes a positive electrode active material, the electrode composition can be used as a slurry for forming a positive electrode active material layer of a secondary battery. Moreover, when the electrode composition contains a negative electrode active material, the electrode composition can be used as a slurry for forming a negative electrode active material layer. Although the binder composition of the present invention can be applied to either a positive electrode composition or a negative electrode composition, it is preferably used for a negative electrode, and is particularly preferably used for a negative electrode composition containing a silicon-based active material.
The above-mentioned active material, conductive aid, and other additives are not particularly limited, and may be appropriately selected from those commonly used in secondary batteries depending on the purpose.
　水溶性高分子（Ｘ）及び水溶性高分子（Ｙ）の、本発明の電極用組成物中の含有量は特に制限されず、全固形分量に対して、合計で０．５～３０質量％が好ましく、１．０～２０質量％がより好ましく、１．５～１５質量％が更に好ましく、２．５～１０質量％が特に好ましい。
　本発明の電極用組成物中、水溶性高分子（Ｘ）と水溶性高分子（Ｙ）との質量比（水溶性高分子（Ｘ）の質量：水溶性高分子（Ｙ）の質量）は特に制限されず、２０～９０：１０～８０が好ましく、４０～８０：２０～６０がより好ましい。
　本発明の電極用組成物が重合体粒子を含有する場合、水溶性高分子（Ｘ）、水溶性高分子（Ｙ）及び重合体粒子の、本発明の電極用組成物中の含有量は特に制限されず、全固形分量に対して、合計で０．５～３０質量％が好ましく、１．０～２０質量％がより好ましく、１．５～１５質量％が更に好ましく、２．５～１０質量％が特に好ましい。
　本発明の電極用組成物中、水溶性高分子（Ｘ）と、水溶性高分子（Ｙ）と、重合体粒子との質量比（水溶性高分子（Ｘ）の質量：水溶性高分子（Ｙ）の質量：重合体粒子の質量）は特に制限されず、１０～８０：１０～８０：１０～５０が好ましく、２０～７０：１０～６０：２０～５０がより好ましい。
　本発明の電極用組成物中、水の含有量は、３０～７０質量％が好ましく、４０～６０質量％がより好ましく、４５～５５質量％が更に好ましい。本発明の電極用組成物が本発明のバインダー組成物を含む場合、本発明の電極用組成物は、本発明のバインダー組成物に由来する水を含み、更に、電極用組成物の調製時に加えられた水を含有していてもよい。
　本発明の電極用組成物中、固形分量は、３０～７０質量％が好ましく、４０～６０質量％がより好ましく、４５～５５質量％が更に好ましい。
　本発明の電極用組成物に含有される全ての固形分に占める、水溶性高分子（Ｘ）、水溶性高分子（Ｙ）、重合体粒子、活物質、及び導電助剤の割合は、合計で、７０質量％以上が好ましく、８０質量％以上がより好ましく、９０質量％以上が更に好ましく、９５質量％以上が特に好ましい。また、本発明の電極用組成物に含有される固形分の全てが水溶性高分子（Ｘ）、水溶性高分子（Ｙ）、重合体粒子、活物質、及び導電助剤であることが最も好ましい。 The content of the water-soluble polymer (X) and the water-soluble polymer (Y) in the electrode composition of the present invention is not particularly limited, and is 0.5 to 30% by mass in total based on the total solid content. is preferable, 1.0 to 20% by weight is more preferable, still more preferably 1.5 to 15% by weight, and particularly preferably 2.5 to 10% by weight.
In the electrode composition of the present invention, the mass ratio of water-soluble polymer (X) to water-soluble polymer (Y) (mass of water-soluble polymer (X): mass of water-soluble polymer (Y)) is There is no particular restriction, but the ratio is preferably 20-90:10-80, more preferably 40-80:20-60.
When the electrode composition of the present invention contains polymer particles, the contents of the water-soluble polymer (X), the water-soluble polymer (Y), and the polymer particles in the electrode composition of the present invention are particularly Without limitation, the total amount is preferably 0.5 to 30% by mass, more preferably 1.0 to 20% by mass, even more preferably 1.5 to 15% by mass, and 2.5 to 10% by mass based on the total solid content. % by weight is particularly preferred.
In the electrode composition of the present invention, the mass ratio of water-soluble polymer (X), water-soluble polymer (Y), and polymer particles (mass of water-soluble polymer (X): water-soluble polymer ( The ratio (mass of Y): mass of polymer particles) is not particularly limited, and is preferably 10 to 80:10 to 80:10 to 50, more preferably 20 to 70:10 to 60:20 to 50.
In the electrode composition of the present invention, the water content is preferably 30 to 70% by mass, more preferably 40 to 60% by mass, and even more preferably 45 to 55% by mass. When the electrode composition of the present invention contains the binder composition of the present invention, the electrode composition of the present invention contains water derived from the binder composition of the present invention, and further contains water added at the time of preparing the electrode composition. may contain water.
In the electrode composition of the present invention, the solid content is preferably 30 to 70% by mass, more preferably 40 to 60% by mass, and even more preferably 45 to 55% by mass.
The proportion of the water-soluble polymer (X), the water-soluble polymer (Y), the polymer particles, the active material, and the conductive aid in the total solid content contained in the electrode composition of the present invention is The content is preferably 70% by mass or more, more preferably 80% by mass or more, even more preferably 90% by mass or more, and particularly preferably 95% by mass or more. Moreover, it is most preferable that all of the solid content contained in the electrode composition of the present invention is the water-soluble polymer (X), the water-soluble polymer (Y), the polymer particles, the active material, and the conductive additive. preferable.
－活物質－
　本発明の電極用組成物は、周期律表第１族又は第２族に属する金属のイオンの挿入放出が可能な活物質を含有する。 -Active material-
The electrode composition of the present invention contains an active material capable of intercalating and ejecting metal ions belonging to Group 1 or Group 2 of the periodic table.
（正極活物質）
　正極活物質は、周期律表第１族又は第２族に属する金属のイオンの挿入放出が可能な活物質であればよく、中でも可逆的にリチウムイオンを挿入及び放出できるものが好ましい。その材料は、上記特性を有するものであれば、特に制限はなく、遷移金属酸化物、有機物、硫黄等のＬｉと複合化できる元素を有する化合物、硫黄と金属の複合物等でもよい。
　中でも、正極活物質としては、遷移金属酸化物を用いることが好ましく、遷移金属元素Ｍａ（Ｃｏ、Ｎｉ、Ｆｅ、Ｍｎ、Ｃｕ及びＶから選択される１種以上の元素）を有する遷移金属酸化物がより好ましい。また、この遷移金属酸化物に元素Ｍｂ（リチウム以外の周期律表の第１（Ｉａ）族の金属元素、第２（ＩＩａ）族の元素、Ａｌ、Ｇａ、Ｉｎ、Ｇｅ、Ｓｎ、Ｐｂ、Ｓｂ、Ｂｉ、Ｓｉ、Ｐ又はＢ等の元素）を混合してもよい。元素Ｍｂの混合量としては、遷移金属元素Ｍａの量１００モル％に対して０～３０モル％が好ましい。遷移金属元素Ｍａに対するＬｉのモル比（Ｌｉ／Ｍａ）が０．３～２．２になるように混合して合成されたものが、より好ましい。
　遷移金属酸化物の具体例としては、（ＭＡ）層状岩塩型構造を有する遷移金属酸化物、（ＭＢ）スピネル型構造を有する遷移金属酸化物、（ＭＣ）リチウム含有遷移金属リン酸化合物、（ＭＤ）リチウム含有遷移金属ハロゲン化リン酸化合物及び（ＭＥ）リチウム含有遷移金属ケイ酸化合物等が挙げられる。 (Cathode active material)
The positive electrode active material may be any active material that can insert and release metal ions belonging to Group 1 or Group 2 of the periodic table, and preferably one that can reversibly insert and release lithium ions. The material is not particularly limited as long as it has the above characteristics, and may be a transition metal oxide, an organic substance, a compound having an element such as sulfur that can be complexed with Li, a composite of sulfur and a metal, or the like.
Among these, it is preferable to use a transition metal oxide as the positive electrode active material, and a transition metal oxide containing a transition metal element M a (one or more elements selected from Co, Ni, Fe, Mn, Cu, and V) is preferable. more preferable. In addition, this transition metal oxide contains elements M b (metal elements of group 1 (Ia) of the periodic table other than lithium, elements of group 2 (IIa) of the periodic table, Al, Ga, In, Ge, Sn, Pb, Elements such as Sb, Bi, Si, P, or B may be mixed. The mixing amount of element M b is preferably 0 to 30 mol % with respect to 100 mol % of transition metal element M a . It is more preferable to synthesize Li by mixing the transition metal element M a with a molar ratio (Li/M a ) of 0.3 to 2.2.
Specific examples of transition metal oxides include (MA) transition metal oxides having a layered rock salt structure, (MB) transition metal oxides having a spinel structure, (MC) lithium-containing transition metal phosphate compounds, (MD ) Lithium-containing transition metal halide phosphoric acid compounds and (ME) lithium-containing transition metal silicate compounds.
　（ＭＡ）層状岩塩型構造を有する遷移金属酸化物の具体例として、ＬｉＣｏＯ２（コバルト酸リチウム［ＬＣＯ］）、ＬｉＮｉ２Ｏ２（ニッケル酸リチウム）、ＬｉＮｉ０．８５Ｃｏ０．１０Ａｌ０．０５Ｏ２（ニッケルコバルトアルミニウム酸リチウム［ＮＣＡ］）、ＬｉＮｉ１／３Ｃｏ１／３Ｍｎ１／３Ｏ２（ニッケルマンガンコバルト酸リチウム［ＮＭＣ］）及びＬｉＮｉ０．５Ｍｎ０．５Ｏ２（マンガンニッケル酸リチウム）が挙げられる。
　（ＭＢ）スピネル型構造を有する遷移金属酸化物の具体例として、ＬｉＭｎ２Ｏ４（ＬＭＯ）、ＬｉＣｏＭｎＯ４、Ｌｉ２ＦｅＭｎ３Ｏ８、Ｌｉ２ＣｕＭｎ３Ｏ８、Ｌｉ２ＣｒＭｎ３Ｏ８及びＬｉ２ＮｉＭｎ３Ｏ８が挙げられる。
　（ＭＣ）リチウム含有遷移金属リン酸化合物としては、例えば、ＬｉＦｅＰＯ４及びＬｉ３Ｆｅ２（ＰＯ４）３等のオリビン型リン酸鉄塩、ＬｉＦｅＰ２Ｏ７等のピロリン酸鉄塩、ＬｉＣｏＰＯ４等のリン酸コバルト塩並びにＬｉ３Ｖ２（ＰＯ４）３（リン酸バナジウムリチウム）等の単斜晶ナシコン型リン酸バナジウム塩が挙げられる。
　（ＭＤ）リチウム含有遷移金属ハロゲン化リン酸化合物としては、例えば、Ｌｉ２ＦｅＰＯ４Ｆ等のフッ化リン酸鉄塩、Ｌｉ２ＭｎＰＯ４Ｆ等のフッ化リン酸マンガン塩及びＬｉ２ＣｏＰＯ４Ｆ等のフッ化リン酸コバルト塩が挙げられる。
　（ＭＥ）リチウム含有遷移金属ケイ酸化合物としては、例えば、Ｌｉ２ＦｅＳｉＯ４、Ｌｉ２ＭｎＳｉＯ４及びＬｉ２ＣｏＳｉＯ４等が挙げられる。
　本発明では、（ＭＡ）層状岩塩型構造を有する遷移金属酸化物が好ましく、ＬＣＯ又はＮＭＣがより好ましい。 (MA) Specific examples of transition metal oxides having a layered rock salt type structure include LiCoO 2 (lithium cobalt oxide [LCO]), LiNi 2 O 2 (lithium nickel oxide), LiNi 0.85 Co 0.10 Al 0. 05 O 2 (nickel cobalt lithium aluminate [NCA]), LiNi 1/3 Co 1/3 Mn 1/3 O 2 (nickel manganese cobalt lithium [NMC]), and LiNi 0.5 Mn 0.5 O 2 ( lithium manganese nickelate).
(MB) Specific examples of transition metal oxides having a spinel structure include LiMn 2 O 4 (LMO), LiCoMnO 4 , Li 2 FeMn 3 O 8 , Li 2 CuMn 3 O 8 , Li 2 CrMn 3 O 8 and Li 2NiMn3O8 is mentioned .
(MC) Examples of lithium-containing transition metal phosphate compounds include olivine-type iron phosphates such as LiFePO 4 and Li 3 Fe 2 (PO 4 ) 3 , iron pyrophosphates such as LiFeP 2 O 7 , LiCoPO 4 , etc. cobalt phosphate salts and monoclinic nasicon type vanadium phosphate salts such as Li 3 V 2 (PO 4 ) 3 (lithium vanadium phosphate).
(MD) Examples of lithium-containing transition metal halide phosphate compounds include iron fluorophosphates such as Li 2 FePO 4 F, manganese fluorophosphates such as Li 2 MnPO 4 F, and Li 2 CoPO 4 F. Examples include cobalt fluorophosphate salts such as.
(ME) Examples of the lithium-containing transition metal silicate compound include Li 2 FeSiO 4 , Li 2 MnSiO 4 and Li 2 CoSiO 4 .
In the present invention, (MA) transition metal oxides having a layered rock salt type structure are preferred, and LCO or NMC is more preferred.
　正極活物質の形状は特に制限されず、粒子状が好ましい。正極活物質の平均粒径（体積基準のメジアン径Ｄ５０）は特に制限されない。例えば、０．１～５０μｍとすることができる。正極活物質を所定の粒子径にするには、粉砕機又は分級機を用い常法により調製すればよい。後述の負極活物質の所定の粒子径への調製方法も適用することができる。焼成法によって得られた正極活物質は、水、酸性水溶液、アルカリ性水溶液又は有機溶剤等にて洗浄した後使用してもよい。
　市販品の正極活物質を用いる場合、正極活物質の平均粒径は製造元のカタログ記載の値を採用する。
　製造元の平均粒径の情報が入手できない場合又は合成した正極活物質を用いる場合は、正極活物質の平均粒径は、後述の負極活物質に記載の方法により測定、算出された値を採用する。 The shape of the positive electrode active material is not particularly limited, and preferably particulate. The average particle diameter (volume-based median diameter D50) of the positive electrode active material is not particularly limited. For example, it can be 0.1 to 50 μm. In order to make the positive electrode active material into a predetermined particle size, it may be prepared by a conventional method using a pulverizer or a classifier. A method for preparing a negative electrode active material to a predetermined particle size, which will be described later, can also be applied. The positive electrode active material obtained by the calcination method may be used after being washed with water, an acidic aqueous solution, an alkaline aqueous solution, an organic solvent, or the like.
When using a commercially available cathode active material, the average particle diameter of the cathode active material is the value listed in the manufacturer's catalog.
If information on the average particle size from the manufacturer is not available or when using a synthesized cathode active material, the average particle size of the cathode active material should be the value measured and calculated by the method described in the negative electrode active material section below. .
　上記焼成法により得られた化合物の化学式は、測定方法として誘導結合プラズマ（ＩＣＰ）発光分光分析法、簡便法として、焼成前後の粉体の質量差から算出できる。 The chemical formula of the compound obtained by the above firing method can be calculated using inductively coupled plasma (ICP) emission spectrometry as a measurement method, or from the difference in mass of the powder before and after firing as a simple method.
　正極活物質の表面は、別の金属酸化物等の酸化物、炭素系材料等で表面被覆されていてもよい。表面被覆材としては、後述する負極活物質の表面被覆に用いうる表面被覆材を用いることができる。 The surface of the positive electrode active material may be coated with another oxide such as a metal oxide, a carbon-based material, or the like. As the surface coating material, a surface coating material that can be used for surface coating of a negative electrode active material, which will be described later, can be used.
　また、正極活物質の表面は硫黄又はリンで表面処理されていてもよい。
　更に、正極活物質の粒子表面は、上記表面被覆の前後において活性光線又は活性気体（プラズマ等）により表面処理を施されていてもよい。 Further, the surface of the positive electrode active material may be surface-treated with sulfur or phosphorus.
Furthermore, the particle surface of the positive electrode active material may be surface-treated with active light or active gas (plasma, etc.) before and after the surface coating.
　上記正極活物質は、１種を単独で用いても、２種以上を組み合わせて用いてもよい。
　正極活物質層を形成する場合、正極活物質層の単位面積（ｃｍ２）当たりの正極活物質の質量（ｍｇ）（目付量）は特に限定されるものではない。設計された電池容量に応じて、適宜に決めることができる。 The above positive electrode active materials may be used alone or in combination of two or more.
When forming a positive electrode active material layer, the mass (mg) (basis weight) of the positive electrode active material per unit area (cm 2 ) of the positive electrode active material layer is not particularly limited. It can be determined as appropriate depending on the designed battery capacity.
　本発明の電極用組成物中における正極活物質の含有量は、特に限定されず、全固形分量に対して、１０～９９質量％が好ましく、３０～９８質量％がより好ましく、５０～９７質量％が更に好ましく、５５～９５質量％が特に好ましい。 The content of the positive electrode active material in the electrode composition of the present invention is not particularly limited, and is preferably 10 to 99% by mass, more preferably 30 to 98% by mass, and 50 to 97% by mass based on the total solid content. % is more preferable, and 55 to 95% by weight is particularly preferable.
（負極活物質）
　負極活物質は、周期律表第１族又は第２族に属する金属のイオンの挿入放出が可能な活物質であればよく、中でも可逆的にリチウムイオンを挿入（吸蔵）及び放出できるものが好ましい。その材料は、上記特性を有するものであれば、特に制限はなく、炭素質材料、ケイ素系材料（ケイ素元素を含有する材料を意味する。）、スズ系材料（スズ元素を含有する材料を意味する。）、金属酸化物、金属複合酸化物、リチウム単体、リチウム合金等が挙げられる。中でも、炭素質材料又はケイ素系材料が信頼性の点から好ましく用いられる。 (Negative electrode active material)
The negative electrode active material may be any active material that can insert and release metal ions belonging to Group 1 or Group 2 of the periodic table, and preferably one that can reversibly insert (occlude) and release lithium ions. . The material is not particularly limited as long as it has the above characteristics, such as carbonaceous materials, silicon-based materials (meaning materials containing the silicon element), tin-based materials (meaning the materials containing the tin element). ), metal oxides, metal composite oxides, simple lithium, lithium alloys, etc. Among these, carbonaceous materials or silicon-based materials are preferably used from the viewpoint of reliability.
　負極活物質として用いられる炭素質材料とは、実質的に炭素からなる材料である。例えば、石油ピッチ、アセチレンブラック等のカーボンブラック、黒鉛（鱗片状黒鉛、塊状黒鉛等の天然黒鉛、気相成長黒鉛、繊維状黒鉛等の人造黒鉛、鱗片状黒鉛を特殊加工してなる膨張黒鉛等）、活性炭、カーボンファイバー、コークス、ソフトカーボン、ハードカーボン、及びＰＡＮ（ポリアクリロニトリル）系の樹脂若しくはフルフリルアルコール樹脂等の各種の合成樹脂を焼成した炭素質材料を挙げることができる。更に、ＰＡＮ系炭素繊維、セルロース系炭素繊維、ピッチ系炭素繊維、気相成長炭素繊維、脱水ＰＶＡ（ポリビニルアルコール）系炭素繊維、リグニン炭素繊維、ガラス状炭素繊維及び活性炭素繊維等の各種炭素繊維類、メソフェーズ微小球体、グラファイトウィスカー並びに平板状の黒鉛等を挙げることもできる。 The carbonaceous material used as the negative electrode active material is a material consisting essentially of carbon. Examples include petroleum pitch, carbon black such as acetylene black, graphite (natural graphite such as flaky graphite and lumpy graphite, artificial graphite such as vapor-grown graphite and fibrous graphite, expanded graphite made by specially processing flaky graphite, etc.) ), activated carbon, carbon fiber, coke, soft carbon, hard carbon, and carbonaceous materials obtained by firing various synthetic resins such as PAN (polyacrylonitrile) resin or furfuryl alcohol resin. Furthermore, various carbon fibers such as PAN carbon fiber, cellulose carbon fiber, pitch carbon fiber, vapor grown carbon fiber, dehydrated PVA (polyvinyl alcohol) carbon fiber, lignin carbon fiber, glassy carbon fiber, and activated carbon fiber. Mention may also be made of mesophase microspheres, graphite whiskers, and tabular graphite.
　負極活物質として用いられるスズ系材料（スズ系活物質）としては、例えば、Ｓｎ、ＳｎＯ、ＳｎＯ２、ＳｎＳ、ＳｎＳ２が挙げられる。 Examples of the tin-based material (tin-based active material) used as the negative electrode active material include Sn, SnO, SnO 2 , SnS, and SnS 2 .
　負極活物質として適用される金属酸化物及び金属複合酸化物としては、周期律表第１族又は第２族に属する金属のイオン（好ましくはリチウムイオン）の挿入放出（好ましくは吸蔵及び放出）が可能な酸化物であれば特に制限されず、金属酸化物としては金属元素の酸化物（金属酸化物）及び、半金属元素の酸化物（半金属酸化物）が挙げられ、金属複合酸化物としては、金属元素の複合酸化物、金属元素と半金属元素との複合酸化物、及び、半金属元素の複合酸化物が挙げられる。
　これらの金属酸化物及び金属複合酸化物としては、非晶質酸化物が好ましく、更に金属元素と周期律表第１６族の元素との反応生成物であるカルコゲナイドも好ましく挙げられる。ここでいう非晶質とは、ＣｕＫα線を用いたＸ線回折法で、２θ値で２０°～４０°の領域に頂点を有するブロードな散乱帯を有するものを意味し、結晶性の回折線を有してもよい。
　上記非晶質酸化物及びカルコゲナイドからなる化合物群の中でも、半金属元素の非晶質酸化物、又は、上記カルコゲナイドがより好ましく、周期律表第１３（ＩＩＩＢ）族～１５（ＶＢ）族の元素（例えば、Ａｌ、Ｇａ、Ｓｉ、Ｓｎ、Ｇｅ、Ｐｂ、Ｓｂ及びＢｉ）のうちの１種単独若しくはそれらの２種以上の組み合わせからなる酸化物もしくは複合酸化物、又はカルコゲナイドが特に好ましい。非晶質酸化物及びカルコゲナイドの具体例としては、例えば、Ｇａ２Ｏ３、ＧｅＯ、ＰｂＯ、ＰｂＯ２、Ｐｂ２Ｏ３、Ｐｂ２Ｏ４、Ｐｂ３Ｏ４、Ｓｂ２Ｏ３、Ｓｂ２Ｏ４、Ｓｂ２Ｏ８Ｂｉ２Ｏ３、Ｓｂ２Ｏ８Ｓｉ２Ｏ３、Ｓｂ２Ｏ５、Ｂｉ２Ｏ３、Ｂｉ２Ｏ４、ＧｅＳ、ＰｂＳ、ＰｂＳ２、Ｓｂ２Ｓ３及びＳｂ２Ｓ５が好ましく挙げられる。 The metal oxides and metal composite oxides used as negative electrode active materials are those that can intercalate and deintercalate (preferably intercalate and deintercalate) metal ions (preferably lithium ions) belonging to Group 1 or Group 2 of the periodic table. There is no particular restriction as long as it is a possible oxide, and metal oxides include oxides of metal elements (metal oxides) and oxides of metalloid elements (metalloid oxides), and metal composite oxides include Examples include composite oxides of metal elements, composite oxides of metal elements and metalloid elements, and composite oxides of metalloid elements.
As these metal oxides and metal composite oxides, amorphous oxides are preferred, and chalcogenides, which are reaction products of metal elements and elements of group 16 of the periodic table, are also preferred. The term "amorphous" as used herein means that it has a broad scattering band with a peak in the 2θ value range of 20° to 40°, as determined by X-ray diffraction using CuKα rays, and the crystalline diffraction line It may have.
Among the compound group consisting of the above-mentioned amorphous oxides and chalcogenides, the amorphous oxides of metalloid elements or the above-mentioned chalcogenides are more preferable, and elements of groups 13 (IIIB) to 15 (VB) of the periodic table are preferred. Particularly preferred are oxides or composite oxides, or chalcogenides consisting of one of the following (for example, Al, Ga, Si, Sn, Ge, Pb, Sb, and Bi) or a combination of two or more thereof. Specific examples of amorphous oxides and chalcogenides include, for example, Ga 2 O 3 , GeO, PbO, PbO 2 , Pb 2 O 3 , Pb 2 O 4 , Pb 3 O 4 , Sb 2 O 3 , Sb 2 O 4 , Sb2O8Bi2O3 , Sb2O8Si2O3 , Sb2O5 , Bi2O3 , Bi2O4 , GeS , PbS , PbS2 , Sb2S3 and Sb2S 5 is preferred.
　金属（複合）酸化物及び上記カルコゲナイドは、構成成分として、チタン及びリチウムの少なくとも一方を含有していることが、高電流密度充放電特性の観点で好ましい。リチウムを含有する金属複合酸化物（リチウム複合金属酸化物）としては、例えば、酸化リチウムと上記金属（複合）酸化物若しくは上記カルコゲナイドとの複合酸化物、より具体的には、Ｌｉ２ＳｎＯ２が挙げられる。 The metal (composite) oxide and the chalcogenide preferably contain at least one of titanium and lithium as a constituent from the viewpoint of high current density charge/discharge characteristics. The metal composite oxide containing lithium (lithium composite metal oxide) is, for example, a composite oxide of lithium oxide and the above metal (composite) oxide or the above chalcogenide, more specifically, Li 2 SnO 2 Can be mentioned.
　負極活物質はチタン元素を含有することも好ましい。より具体的にはＴｉＮｂ２Ｏ７（チタン酸ニオブ酸化物［ＮＴＯ］）、Ｌｉ４Ｔｉ５Ｏ１２（チタン酸リチウム［ＬＴＯ］）がリチウムイオンの吸蔵放出時の体積変動が小さいことから急速充放電特性に優れ、電極の劣化が抑制され、リチウムイオン二次電池のサイクル特性向上が可能となる点で好ましい。 It is also preferable that the negative electrode active material contains titanium element. More specifically, TiNb 2 O 7 (niobium titanate oxide [NTO]) and Li 4 Ti 5 O 12 (lithium titanate [LTO]) have small volume fluctuations when lithium ions are absorbed and released, so they are suitable for rapid charging. It is preferable because it has excellent discharge characteristics, suppresses electrode deterioration, and makes it possible to improve the cycle characteristics of a lithium ion secondary battery.
　負極活物質としてのリチウム合金としては、二次電池の負極活物質として通常用いられる合金であれば特に制限されず、例えば、リチウムアルミニウム合金が挙げられる。 The lithium alloy as a negative electrode active material is not particularly limited as long as it is an alloy commonly used as a negative electrode active material of secondary batteries, and examples thereof include lithium aluminum alloys.
　ケイ素系材料（ケイ素系活物質）としては、ケイ素元素を含む負極活物質であり、例えば、Ｓｉ、ＳｉＯｘ（０＜ｘ≦１．５）等のケイ素材料、更には、チタン、バナジウム、クロム、マンガン、ニッケル、銅若しくはランタンを含むケイ素含有合金（例えば、ＬａＳｉ２、ＶＳｉ２）、又は組織化した活物質（例えば、ＬａＳｉ２／Ｓｉ）、他にも、上述の金属酸化物及び金属複合酸化物の記載におけるケイ素元素を含む酸化物又は複合酸化物、ＳｎＳｉＯ３、ＳｎＳｉＳ３等のケイ素元素及びスズ元素を含む活物質等が挙げられる。
　ＳｉＯｘは、それ自体を負極活物質（半金属酸化物）として用いることができ、また、電池の稼働によりＳｉを生成するため、リチウムと合金形成可能な活物質（その前駆体物質）として用いることができる。 The silicon-based material (silicon-based active material) is a negative electrode active material containing the silicon element, such as silicon materials such as Si and SiOx (0<x≦1.5), as well as titanium, vanadium, chromium, Silicon-containing alloys (e.g. LaSi 2 , VSi 2 ) containing manganese, nickel, copper or lanthanum, or structured active materials (e.g. LaSi 2 /Si), as well as the metal oxides and metal composite oxides mentioned above. Examples include oxides or composite oxides containing silicon elements in the description of products, and active materials containing silicon elements and tin elements such as SnSiO 3 and SnSiS 3 .
SiOx itself can be used as a negative electrode active material (semi-metal oxide), and since Si is generated during battery operation, it can be used as an active material (its precursor material) that can form an alloy with lithium. Can be done.
　上記では負極活物質を成分に着目して説明しているが、特性の観点からは、負極活物質は、リチウムと合金形成可能な負極活物質であることが好ましい。
　リチウムと合金形成可能な負極活物質は、二次電池の負極活物質として通常用いられるものであれば特に制限されない。このような活物質として、上述のケイ素元素及び／又はスズ元素を含む負極活物質、Ａｌ及びＩｎ等の各金属が挙げられる。より高い電池容量を可能とする点でケイ素系活物質が好ましく、ケイ素元素の含有量が全構成元素の４０モル％以上であるケイ素系活物質がより好ましい。
　一般的に、これらのリチウムと合金形成可能な負極活物質を含有する負極（例えば、ケイ素系活物質を含むＳｉ負極、スズ系活物質を含むＳｎ負極）は、炭素質材料のみからなる負極（黒鉛、カーボンブラック等）に比べて、より多くのＬｉイオンを吸蔵できる。すなわち、単位質量あたりのＬｉイオンの吸蔵量が増加する。そのため、電池容量（エネルギー密度）を大きくすることができる。その結果、バッテリー駆動時間を長くすることができるという利点がある。このように、ケイ素元素及び／又はスズ元素を含む負極活物質などのリチウムと合金形成可能な負極活物質は、高容量活物質とも称される。 Although the negative electrode active material has been described above focusing on its components, from the viewpoint of characteristics, the negative electrode active material is preferably a negative electrode active material that can form an alloy with lithium.
The negative electrode active material capable of forming an alloy with lithium is not particularly limited as long as it is commonly used as a negative electrode active material of secondary batteries. Examples of such active materials include negative electrode active materials containing the silicon element and/or tin element described above, and metals such as Al and In. A silicon-based active material is preferable because it enables higher battery capacity, and a silicon-based active material in which the content of silicon element is 40 mol % or more of all constituent elements is more preferable.
In general, negative electrodes containing negative electrode active materials that can be alloyed with lithium (e.g., Si negative electrodes containing silicon-based active materials, Sn negative electrodes containing tin-based active materials) are different from negative electrodes made only of carbonaceous materials ( It can store more Li ions than graphite, carbon black, etc.). That is, the amount of Li ions stored per unit mass increases. Therefore, battery capacity (energy density) can be increased. As a result, there is an advantage that the battery operating time can be extended. In this way, a negative electrode active material that can form an alloy with lithium, such as a negative electrode active material containing a silicon element and/or a tin element, is also referred to as a high-capacity active material.
　負極活物質の表面は、別の金属酸化物等の酸化物、炭素系材料等で表面被覆されていてもよい（以下、炭素系材料で表面被覆されていることを「カーボンコートされた」と記載することがある）。表面被覆材としてはＴｉ、Ｎｂ、Ｔａ、Ｗ、Ｚｒ、Ａｌ、Ｓｉ又はＬｉを含有する金属酸化物等が挙げられる。具体的には、チタン酸スピネル、タンタル系酸化物、ニオブ系酸化物、ニオブ酸リチウム系化合物等が挙げられ、更に具体的には、Ｌｉ４Ｔｉ５Ｏ１２、Ｌｉ２Ｔｉ２Ｏ５、ＬｉＴａＯ３、ＬｉＮｂＯ３、ＬｉＡｌＯ２、Ｌｉ２ＺｒＯ３、Ｌｉ２ＷＯ４、Ｌｉ２ＴｉＯ３、Ｌｉ２Ｂ４Ｏ７、Ｌｉ３ＰＯ４、Ｌｉ２ＭｏＯ４、Ｌｉ３ＢＯ３、ＬｉＢＯ２、Ｌｉ２ＣＯ３、Ｌｉ２ＳｉＯ３、ＳｉＯ２、ＴｉＯ２、ＺｒＯ２、Ａｌ２Ｏ３、Ｂ２Ｏ３等が挙げられる。また、Ｃ、ＳｉＣ、炭素添加シリコン酸化物等の炭素系材料も表面被覆材として用いることができる。 The surface of the negative electrode active material may be coated with an oxide such as another metal oxide, a carbon-based material, etc. (hereinafter, surface coating with a carbon-based material is referred to as "carbon-coated"). ). Examples of the surface coating material include metal oxides containing Ti, Nb, Ta, W, Zr, Al, Si, or Li. Specific examples include spinel titanate, tantalum oxides, niobium oxides, lithium niobate compounds, and more specifically, Li 4 Ti 5 O 12 , Li 2 Ti 2 O 5 , LiTaO 3 , LiNbO3 , LiAlO2 , Li2ZrO3 , Li2WO4 , Li2TiO3 , Li2B4O7 , Li3PO4 , Li2MoO4 , Li3BO3 , LiBO2 , Li2 Examples include CO 3 , Li 2 SiO 3 , SiO 2 , TiO 2 , ZrO 2 , Al 2 O 3 and B 2 O 3 . Further, carbon-based materials such as C, SiC, and carbon-doped silicon oxide can also be used as surface coating materials.
　また、負極活物質の表面は硫黄又はリンで表面処理されていてもよい。
　更に、負極活物質の粒子表面は、上記表面被覆の前後において活性光線又は活性気体（プラズマ等）により表面処理を施されていてもよい。 Further, the surface of the negative electrode active material may be surface-treated with sulfur or phosphorus.
Furthermore, the particle surface of the negative electrode active material may be surface-treated with active light or active gas (plasma, etc.) before and after the surface coating.
　負極活物質は、金属元素をドープされていてもよい。金属元素がドープされた負極活物質（「金属ドープ活物質」とも称す。）において、ドープされる金属元素は、Ｌｉ、Ｎｉ及びＴｉの少なくともいずれか１種であることが好ましく、Ｌｉであることがより好ましい。 The negative electrode active material may be doped with a metal element. In the negative electrode active material doped with a metal element (also referred to as "metal-doped active material"), the metal element doped is preferably at least one of Li, Ni, and Ti, and preferably Li. is more preferable.
　本発明においては、負極活物質として、ケイ素系活物質を用いることが好ましく、酸化ケイ素（ＳｉＯｘ（０＜ｘ≦１．５））又はカーボンコートされた酸化ケイ素（カーボンコートされたＳｉＯｘ（０＜ｘ≦１．５））を用いることがより好ましく、カーボンコートされた酸化ケイ素を用いることが更に好ましい。カーボンコートされた酸化ケイ素は、さらに金属元素をドープされていてもよい。
　カーボンコートされた酸化ケイ素中に占める炭素元素の含有量の割合は特に制限されず、例えば、０．５～５質量％が好ましく、１～３質量％がより好ましい。
　酸化ケイ素又はカーボンコートされた酸化ケイ素は市販品を用いてもよい。また、例えば特開２０１９－２０４６８６号公報を参照して、酸化ケイ素をカーボンコートすることにより調製することもできる。
　負極活物質中の酸化ケイ素又はカーボンコートされた酸化ケイ素の含有量は特に制限されず、例えば１０～９０質量％とすることができ、１０～５０質量％が好ましく、１５～４０質量％がより好ましい。
　負極活物質が酸化ケイ素又はカーボンコートされた酸化ケイ素である場合、平均粒径は５～２０μｍが好ましい。
　本発明においては、負極活物質として、金属元素をドープされたケイ素系材料を用いることも好ましく、Ｌｉ、Ｎｉ及びＴｉの少なくともいずれか１種をドープされたケイ素系材料がより好ましく、Ｌｉをドープされたケイ素系材料がさらに好ましい。金属元素のドープに付されるケイ素系材料としては、酸化ケイ素又はカーボンコートされた酸化ケイ素が好ましい。
　金属元素をドープされた酸化ケイ素、並びに、金属元素のドープ及びカーボンコートの両方が施された酸化ケイ素としては、市販品を用いてもよい。また、例えば、特開２０２２－１２１５８２号公報、国際公開第１４／１８８８５１号及び特開２０２１－１５００７７号公報等を参照して、酸化ケイ素又はカーボンコートされた酸化ケイ素に金属元素をドープすること、又は、酸化ケイ素に金属元素をドープし、必要に応じてさらにカーボンコートを施すことにより調製することもできる。
　本発明において、「金属元素のドープ及びカーボンコートの両方が施された」とは、金属元素のドープを施した後、カーボンコート処理を施したもの、及び、カーボンコート処理を施した後、金属元素のドープを施したものの両方を含む意味で使用する。
　本発明においては、負極活物質として、金属元素のドープ及びカーボンコートの両方が施されたケイ素系材料を用いることも好ましく、このような負極活物質としては、金属元素のドープ及びカーボンコートの両方が施された酸化ケイ素がより好ましく、リチウムドープ及びカーボンコートの両方が施された酸化ケイ素が特に好ましい。 In the present invention, it is preferable to use a silicon-based active material as the negative electrode active material, and silicon oxide (SiO x (0<x≦1.5)) or carbon-coated silicon oxide (carbon-coated SiO x ( It is more preferable to use 0<x≦1.5), and even more preferable to use carbon-coated silicon oxide. The carbon-coated silicon oxide may be further doped with a metal element.
The content ratio of the carbon element in the carbon-coated silicon oxide is not particularly limited, and is preferably 0.5 to 5% by mass, more preferably 1 to 3% by mass.
Commercially available silicon oxide or carbon-coated silicon oxide may be used. Alternatively, it can also be prepared by coating silicon oxide with carbon, for example, with reference to JP-A-2019-204686.
The content of silicon oxide or carbon-coated silicon oxide in the negative electrode active material is not particularly limited, and can be, for example, 10 to 90% by mass, preferably 10 to 50% by mass, and more preferably 15 to 40% by mass. preferable.
When the negative electrode active material is silicon oxide or carbon-coated silicon oxide, the average particle size is preferably 5 to 20 μm.
In the present invention, it is also preferable to use a silicon-based material doped with a metal element as the negative electrode active material, more preferably a silicon-based material doped with at least one of Li, Ni, and Ti. More preferred are silicon-based materials. The silicon-based material to be doped with the metal element is preferably silicon oxide or carbon-coated silicon oxide.
Commercially available products may be used as the silicon oxide doped with a metal element and the silicon oxide doped with a metal element and coated with carbon. Further, for example, doping silicon oxide or carbon-coated silicon oxide with a metal element, with reference to JP 2022-121582, WO 14/188851, JP 2021-150077, etc. Alternatively, it can also be prepared by doping silicon oxide with a metal element and, if necessary, further applying a carbon coat.
In the present invention, "both doped with a metal element and carbon coated" refers to a product that is doped with a metal element and then subjected to a carbon coat treatment, and a product that is doped with a metal element and then subjected to a carbon coat treatment; Used to include both elements doped.
In the present invention, it is also preferable to use a silicon-based material doped with a metal element and coated with carbon as the negative electrode active material. Silicon oxide coated with lithium is more preferred, and silicon oxide coated with both lithium and carbon is particularly preferred.
　負極活物質の形状は特に制限されないが粒子状が好ましい。負極活物質の平均粒径（体積基準のメジアン径Ｄ５０）は、０．１～６０μｍが好ましい。所定の粒子径にするには、粉砕機又は分級機を用い常法により調製することができる。例えば、乳鉢、ボールミル、サンドミル、振動ボールミル、衛星ボールミル、遊星ボールミル、旋回気流型ジェットミル又は篩等が好適に用いられる。粉砕時には水又はメタノール等の有機溶媒を共存させた湿式粉砕も行うことができる。所望の粒子径とするためには分級を行うことが好ましい。分級方法としては、特に限定はなく、篩、風力分級機等を所望により用いることができる。分級は乾式及び湿式ともに用いることができる。
　市販品の負極活物質を用いる場合、負極活物質の平均粒径は製造元のカタログ記載の値を採用する。
　製造元の平均粒径の情報が入手できない場合又は合成した負極活物質を用いる場合は、負極活物質を水中で分散させ、レーザ回折／散乱式粒子径分布測定装置（例えば、ＨＯＲＩＢＡ社製のＰａｒｔｉｃｌｅ　ＬＡ－９６０Ｖ２（商品名））で測定して得られる平均粒径の値（水中での体積基準のメジアン径Ｄ５０）を採用する。
　なお、水中で不安定な負極活物質はＳＥＭ（Scanning Electron Microscope）観察等の他の方法により測定、算出してもよい。 The shape of the negative electrode active material is not particularly limited, but a particulate shape is preferable. The average particle diameter (volume-based median diameter D50) of the negative electrode active material is preferably 0.1 to 60 μm. A predetermined particle size can be prepared by a conventional method using a crusher or a classifier. For example, a mortar, a ball mill, a sand mill, a vibrating ball mill, a satellite ball mill, a planetary ball mill, a swirling jet mill, a sieve, etc. are preferably used. Wet pulverization can also be carried out in the presence of water or an organic solvent such as methanol during pulverization. In order to obtain a desired particle size, it is preferable to perform classification. The classification method is not particularly limited, and a sieve, a wind classifier, etc. can be used as desired. Both dry and wet classification can be used.
When using a commercially available negative electrode active material, the average particle diameter of the negative electrode active material is the value stated in the manufacturer's catalog.
If information on the average particle size from the manufacturer is not available or if a synthesized negative electrode active material is used, disperse the negative electrode active material in water and use a laser diffraction/scattering particle size distribution measuring device (for example, Particle LA manufactured by HORIBA). -960V2 (trade name)), the average particle diameter value (volume-based median diameter D50 in water) is adopted.
Note that the negative electrode active material, which is unstable in water, may be measured and calculated by other methods such as SEM (Scanning Electron Microscope) observation.
　負極活物質は、１種を単独で用いても、２種以上を組み合わせて用いてもよい。その中でも、ケイ素系活物質と炭素質材料の組み合わせが好ましく、ケイ素系活物質と黒鉛との組み合わせがより好ましく、酸化ケイ素及び／又はカーボンコートされた酸化ケイ素と、黒鉛との組み合わせがさらに好ましい。酸化ケイ素及びカーボンコートされた酸化ケイ素は、それぞれ、上述の金属元素のドープが施された酸化ケイ素及び金属元素のドープ及びカーボンコートの両方が施された酸化ケイ素であってもよい。ドープされる金属元素は、Ｌｉ、Ｎｉ及びＴｉの少なくともいずれか１種であることが好ましく、Ｌｉであることがより好ましい。
　ケイ素系活物質と黒鉛とを組み合わせる場合、黒鉛に対するケイ素系活物質の質量比率（ケイ素系活物質／黒鉛）は２以下が好ましく、１以下がより好ましく、０．５以下が更に好ましい。黒鉛に対するケイ素系活物質の質量比率の下限値に特に制限はないが、０．０５以上が実際的である。 The negative electrode active materials may be used alone or in combination of two or more. Among these, a combination of a silicon-based active material and a carbonaceous material is preferred, a combination of a silicon-based active material and graphite is more preferred, and a combination of silicon oxide and/or carbon-coated silicon oxide and graphite is even more preferred. The silicon oxide and carbon-coated silicon oxide may be silicon oxide doped with the above-mentioned metal element and silicon oxide doped with both the metal element and carbon coating, respectively. The metal element to be doped is preferably at least one of Li, Ni, and Ti, and more preferably Li.
When combining a silicon-based active material and graphite, the mass ratio of the silicon-based active material to graphite (silicon-based active material/graphite) is preferably 2 or less, more preferably 1 or less, and even more preferably 0.5 or less. Although there is no particular restriction on the lower limit of the mass ratio of silicon-based active material to graphite, 0.05 or more is practical.
　負極活物質層を形成する場合、負極活物質層の単位面積（ｃｍ２）当たりの負極活物質の質量（ｍｇ）（目付量）は特に限定されるものではない。設計された電池容量に応じて、適宜に決めることができる。 When forming a negative electrode active material layer, the mass (mg) (basis weight) of the negative electrode active material per unit area (cm 2 ) of the negative electrode active material layer is not particularly limited. It can be determined as appropriate depending on the designed battery capacity.
　負極活物質の、本発明の電極用組成物中における含有量は、特に限定されず、全固形分量に対して、１０～９９質量％であることが好ましく、３０～９８質量％がより好ましく、４５～９７質量％が更に好ましく、５５～９５質量％が特に好ましい。 The content of the negative electrode active material in the electrode composition of the present invention is not particularly limited, and is preferably 10 to 99% by mass, more preferably 30 to 98% by mass, based on the total solid content. More preferably 45 to 97% by weight, particularly preferably 55 to 95% by weight.
　本発明において、負極活物質層を電池の充電により形成する場合、上記負極活物質に代えて、二次電池内に発生する周期律表第１族若しくは第２族に属する金属のイオンを用いることができる。このイオンを電子と結合させて金属として析出させることで、負極活物質層を形成できる。 In the present invention, when the negative electrode active material layer is formed by charging the battery, metal ions belonging to Group 1 or Group 2 of the periodic table generated in the secondary battery may be used in place of the negative electrode active material. Can be done. A negative electrode active material layer can be formed by combining these ions with electrons and depositing them as metal.
（導電助剤）
　本発明の電極用組成物は、導電助剤を含有することもでき、特に負極活物質としてのケイ素系活物質は導電助剤と併用されることが好ましい。
　導電助剤としては、特に制限はなく、一般的な導電助剤として知られているものを用いることができる。例えば、電子伝導性材料である、アセチレンブラック、ケッチェンブラック、ファーネスブラック等のカーボンブラック類、ニードルコークス等の無定形炭素、気相成長炭素繊維若しくはカーボンナノチューブ等の炭素繊維類、グラフェン若しくはフラーレン等の炭素質材料であってもよいし、銅、ニッケル等の金属粉、金属繊維でもよく、ポリアニリン、ポリピロール、ポリチオフェン、ポリアセチレン、ポリフェニレン誘導体等の導電性高分子を用いてもよい。
　本発明において、活物質と導電助剤とを併用する場合、上記の導電助剤のうち、電池を充放電した際にＬｉの挿入と放出が起きず、活物質として機能しないものを導電助剤とする。したがって、導電助剤の中でも、電池を充放電した際に活物質層中において活物質として機能しうるものは、導電助剤ではなく活物質に分類する。電池を充放電した際に活物質として機能するか否かは、一義的ではなく、活物質との組み合わせにより決定される。 (conductivity aid)
The electrode composition of the present invention may also contain a conductive additive, and it is particularly preferable that a silicon-based active material as a negative electrode active material is used in combination with a conductive additive.
There are no particular limitations on the conductive aid, and those known as general conductive aids can be used. For example, electron conductive materials such as carbon black such as acetylene black, Ketjen black, and furnace black, amorphous carbon such as needle coke, carbon fibers such as vapor-grown carbon fiber or carbon nanotubes, graphene or fullerene, etc. The material may be a carbonaceous material, metal powder such as copper or nickel, or metal fiber, or a conductive polymer such as polyaniline, polypyrrole, polythiophene, polyacetylene, or polyphenylene derivative.
In the present invention, when an active material and a conductive additive are used together, among the conductive additives mentioned above, one that does not insert or release Li when the battery is charged or discharged and does not function as an active material is selected as the conductive additive. shall be. Therefore, among conductive aids, those that can function as active materials in the active material layer when the battery is charged and discharged are classified as active materials rather than conductive aids. Whether or not it functions as an active material when charging and discharging a battery is not unique, but is determined by the combination with the active material.
　導電助剤は、１種を単独で用いても、２種以上を組み合わせて用いてもよい。
　導電助剤の、本発明の電極用組成物中の含有量は、全固形分量に対して、０．５～６０質量％が好ましく、１．０～５０質量％がより好ましく、１．５～４０質量％が更に好ましく、２．５～３５質量％が特に好ましい。 The conductive aids may be used alone or in combination of two or more.
The content of the conductive aid in the electrode composition of the present invention is preferably 0.5 to 60% by mass, more preferably 1.0 to 50% by mass, and 1.5 to 50% by mass, based on the total solid content. 40% by weight is more preferable, and 2.5 to 35% by weight is particularly preferable.
　導電助剤の形状は、特に制限されないが、粒子状が好ましい。導電助剤の平均粒径（水中での体積換算（体積基準）のメジアン径Ｄ５０）は、特に限定されず、例えば、０．０１～５０μｍが好ましく、０．０２～１０．０μｍがより好ましい。
　市販品の導電助剤を用いる場合、導電助剤の平均粒径は製造元のカタログ記載の値を採用する。
　製造元の平均粒径の情報が入手できない場合又は合成した導電助剤を用いる場合は、導電助剤の平均粒径は、前述した負極活物質の平均粒径（水中での体積基準のメジアン径Ｄ５０）の測定方法を適用して得られた値を採用すればよい。 The shape of the conductive aid is not particularly limited, but is preferably particulate. The average particle size (median diameter D50 in terms of volume (volume basis) in water) of the conductive additive is not particularly limited, and is preferably, for example, 0.01 to 50 μm, more preferably 0.02 to 10.0 μm.
When using a commercially available conductive aid, the average particle diameter of the conductive aid is the value listed in the manufacturer's catalog.
If information on the average particle size from the manufacturer is not available or when using a synthesized conductive additive, the average particle size of the conductive additive should be the average particle diameter of the negative electrode active material described above (volume-based median diameter D50 in water). ) may be used.
（他の添加剤）
　本発明の電極用組成物は、上記各成分以外の他の成分として、所望により、リチウム塩、イオン液体、増粘剤、消泡剤、レベリング剤、脱水剤、酸化防止剤等を含有することができる。
　上記活物質、導電助剤、他の添加剤に関し、例えば、国際公開第２０１９／２０３３３４号、特開２０１５－４６３８９号公報等を参照することができる。 (Other additives)
The electrode composition of the present invention may optionally contain a lithium salt, an ionic liquid, a thickener, an antifoaming agent, a leveling agent, a dehydrating agent, an antioxidant, etc. as other components other than the above-mentioned components. Can be done.
Regarding the above-mentioned active material, conductive aid, and other additives, reference can be made to, for example, International Publication No. 2019/203334, JP 2015-46389, etc.
［二次電池用バインダー組成物及び電極用組成物の調製方法］
　本発明の二次電池用バインダー組成物は、水溶性高分子（Ｘ）及び水溶性高分子（Ｙ）、好ましくは更に、重合体粒子及び／又は水、更には適宜に、任意の他の成分を、例えば通常用いる各種の混合機で混合することにより、混合物として、好ましくはスラリーとして、調製することができる。本発明の電極用組成物の場合は、上記に加えて活物質を、更には適宜に、導電助剤、他の添加剤等を、混合する。
　混合方法は特に制限されず、一括して混合してもよく、順次混合してもよい。また、複数の成分を混合して得られる混合物を他の成分と混合してもよい。
　例えば、水溶性高分子（Ｘ）、水溶性高分子（Ｙ）及び水（電極用組成物の場合には、更に、活物質、導電助剤）を混合した後、水と重合体粒子を加えて更に混合して、バインダー組成物（電極用組成物）を得ることもできる。 [Preparation method of binder composition for secondary battery and composition for electrode]
The binder composition for a secondary battery of the present invention comprises a water-soluble polymer (X) and a water-soluble polymer (Y), preferably further polymer particles and/or water, and optionally any other components. A mixture, preferably a slurry, can be prepared by mixing, for example, in various commonly used mixers. In the case of the electrode composition of the present invention, in addition to the above, an active material is mixed, and further a conductive aid, other additives, etc. are mixed as appropriate.
The mixing method is not particularly limited, and may be mixed all at once or sequentially. Further, a mixture obtained by mixing a plurality of components may be mixed with other components.
For example, after mixing a water-soluble polymer (X), a water-soluble polymer (Y), and water (in the case of an electrode composition, an active material and a conductive aid), water and polymer particles are added. A binder composition (electrode composition) can also be obtained by further mixing.
［電極シート］
　本発明の電極シートは、本発明の電極用組成物を用いて形成された層（電極活物質層、すなわち、負極活物質層又は正極活物質層）を有する。本発明の電極シートは、本発明の電極用組成物を用いて形成された電極活物質層を有する電極シートであればよく、電極活物質層が、集電体等の基材上に形成されているシートでも、基材を有さず、電極活物質層（負極活物質層又は正極活物質層）だけで形成されているシートであってもよい。この電極シートは、通常、集電体上に電極活物質層を積層した構成のシートである。本発明の電極シートは、他の層として、例えば、剥離シート等の保護層、コート層を有してもよい。
　本発明の電極シートは、二次電池の負極活物質層又は正極活物質層を構成する材料、あるいは、負極集電体と負極活物質層の積層体（負極層）又は正極集電体と正極活物質層の積層体（正極層）として好適に用いることができる。 [Electrode sheet]
The electrode sheet of the present invention has a layer (electrode active material layer, that is, a negative electrode active material layer or a positive electrode active material layer) formed using the electrode composition of the present invention. The electrode sheet of the present invention may be an electrode sheet having an electrode active material layer formed using the electrode composition of the present invention, and the electrode active material layer may be formed on a base material such as a current collector. It may be a sheet that does not have a base material and is formed only of an electrode active material layer (a negative electrode active material layer or a positive electrode active material layer). This electrode sheet usually has a structure in which an electrode active material layer is laminated on a current collector. The electrode sheet of the present invention may have other layers such as a protective layer such as a release sheet and a coating layer.
The electrode sheet of the present invention is a material constituting a negative electrode active material layer or a positive electrode active material layer of a secondary battery, or a laminate of a negative electrode current collector and a negative electrode active material layer (negative electrode layer), or a positive electrode current collector and a positive electrode. It can be suitably used as a laminate of active material layers (positive electrode layer).
　本発明の電極シートが集電体を有する場合、本発明の電極シートを構成する集電体は、電子伝達体であり、通常はフィルムシート状である。集電体は、活物質に応じて適宜選択することができる。
　正極集電体の構成材料としては、アルミニウム、アルミニウム合金、ステンレス鋼、ニッケル、及び、チタンが挙げられ、アルミニウム又はアルミニウム合金が好ましい。なお、正極集電体としては、アルミニウム又はステンレス鋼の表面にカーボン、ニッケル、チタン又は銀を処理させ、コート層（薄膜）を形成したものも挙げられる。
　負極集電体の構成材料としては、アルミニウム、銅、銅合金、ステンレス鋼、ニッケル、及び、チタンが挙げられ、アルミニウム、銅、銅合金、又は、ステンレス鋼が好ましい。なお、負極集電体としては、アルミニウム、銅、銅合金又はステンレス鋼の表面にカーボン、ニッケル、チタン又は銀を処理させ、コート層（薄膜）を形成したものも挙げられる。 When the electrode sheet of the present invention has a current collector, the current collector constituting the electrode sheet of the present invention is an electron carrier and is usually in the form of a film sheet. The current collector can be appropriately selected depending on the active material.
Examples of the constituent material of the positive electrode current collector include aluminum, aluminum alloy, stainless steel, nickel, and titanium, with aluminum or aluminum alloy being preferred. Note that examples of the positive electrode current collector include those obtained by treating the surface of aluminum or stainless steel with carbon, nickel, titanium, or silver to form a coating layer (thin film).
Examples of the constituent material of the negative electrode current collector include aluminum, copper, copper alloy, stainless steel, nickel, and titanium, with aluminum, copper, copper alloy, or stainless steel being preferred. Note that examples of the negative electrode current collector include those obtained by treating the surface of aluminum, copper, copper alloy, or stainless steel with carbon, nickel, titanium, or silver to form a coating layer (thin film).
　本発明の電極シートを構成する正極活物質層の厚さは特に制限されず、例えば、５～５００μｍとすることができ、２０～２００μｍが好ましい。
　また、本発明の電極シートを構成する正極集電体の厚さは特に制限されず、例えば、１０～１００μｍとすることができ、１０～５０μｍが好ましい。 The thickness of the positive electrode active material layer constituting the electrode sheet of the present invention is not particularly limited, and can be, for example, 5 to 500 μm, preferably 20 to 200 μm.
Further, the thickness of the positive electrode current collector constituting the electrode sheet of the present invention is not particularly limited, and may be, for example, 10 to 100 μm, preferably 10 to 50 μm.
　本発明の電極シートを構成する負極活物質層の厚さは特に制限されず、例えば、５～５００μｍとすることができ、２０～２００μｍが好ましい。
　また、本発明の電極シートを構成する負極集電体の厚さは特に制限されず、例えば、１０～１００μｍとすることができ、１０～５０μｍが好ましい。 The thickness of the negative electrode active material layer constituting the electrode sheet of the present invention is not particularly limited, and can be, for example, 5 to 500 μm, preferably 20 to 200 μm.
Further, the thickness of the negative electrode current collector constituting the electrode sheet of the present invention is not particularly limited, and can be, for example, 10 to 100 μm, preferably 10 to 50 μm.
［電極シートの製造方法］
　本発明の電極シートは、本発明の電極用組成物を用いて電極活物質層を形成することにより得ることができる。例えば、本発明の電極用組成物を用いて製膜することにより、本発明の電極シートを製造することができる。具体的には、集電体等を基材として、その上（他の層を介していてもよい）に本発明の電極用組成物を塗布して塗膜を形成し、これを乾燥して、基材上に活物質層（塗布乾燥層）を有する電極シートを得ることができる。
　また、本発明の二次電池は、上記電極シートの製造方法により得られた電極シートを二次電池の電極（正極及び負極）の少なくとも一方に組み込むことにより得ることができる。 [Method for manufacturing electrode sheet]
The electrode sheet of the present invention can be obtained by forming an electrode active material layer using the electrode composition of the present invention. For example, the electrode sheet of the present invention can be manufactured by forming a film using the electrode composition of the present invention. Specifically, the electrode composition of the present invention is applied onto a current collector or the like as a base material (possibly via another layer) to form a coating film, and this is dried. , it is possible to obtain an electrode sheet having an active material layer (coated dry layer) on a base material.
Moreover, the secondary battery of the present invention can be obtained by incorporating the electrode sheet obtained by the above method for manufacturing an electrode sheet into at least one of the electrodes (positive electrode and negative electrode) of the secondary battery.
［二次電池］
　本発明の二次電池は、正極活物質層及び負極活物質層の少なくとも１つの層が、本発明の電極用組成物を用いて形成された層である。
　本発明の二次電池について、非水電解液二次電池の形態を例にして説明するが、本発明の二次電池は非水電解液二次電池に限定されるものではなく、二次電池全般を広く包含するものである。 [Secondary battery]
In the secondary battery of the present invention, at least one of the positive electrode active material layer and the negative electrode active material layer is a layer formed using the electrode composition of the present invention.
The secondary battery of the present invention will be explained using the form of a non-aqueous electrolyte secondary battery as an example, but the secondary battery of the present invention is not limited to a non-aqueous electrolyte secondary battery. It broadly encompasses everything.
　本発明の好ましい一実施形態である非水電解液二次電池は、正極と、負極と、正極と負極との間に配されたセパレータとを含む構成を有する。正極は、正極集電体と、この正極集電体に接する正極活物質層とを有し、負極は、負極集電体と、この負極集電体に接する負極活物質層とを有する。本発明の非水電解液二次電池は、上記正極活物質層及び上記負極活物質層の少なくとも１つの層が、本発明の電極用組成物を用いて形成されている。なお、本発明の非水電解液二次電池には、正極活物質層及び負極活物質層のいずれか一方のみを有し、この本発明の非水電解液二次電池が有する電極活物質層が、本発明の電極用組成物を用いて形成されている構成の非水電解液二次電池も含まれる。本発明の非水電解液二次電池は、正極と負極との間に非水電解液を満たすことにより、充放電により二次電池として機能する。 A non-aqueous electrolyte secondary battery that is a preferred embodiment of the present invention has a configuration including a positive electrode, a negative electrode, and a separator disposed between the positive electrode and the negative electrode. The positive electrode has a positive electrode current collector and a positive electrode active material layer in contact with the positive electrode current collector, and the negative electrode has a negative electrode current collector and a negative electrode active material layer in contact with the negative electrode current collector. In the non-aqueous electrolyte secondary battery of the present invention, at least one of the positive electrode active material layer and the negative electrode active material layer is formed using the electrode composition of the present invention. Note that the nonaqueous electrolyte secondary battery of the present invention has only one of a positive electrode active material layer and a negative electrode active material layer, and the electrode active material layer of the nonaqueous electrolyte secondary battery of the present invention has only one of a positive electrode active material layer and a negative electrode active material layer. However, non-aqueous electrolyte secondary batteries formed using the electrode composition of the present invention are also included. The non-aqueous electrolyte secondary battery of the present invention functions as a secondary battery by charging and discharging by filling a non-aqueous electrolyte between the positive electrode and the negative electrode.
　図１は、一般的な非水電解液二次電池１０の積層構造を、電池として作動させる際の作動電極も含めて、模式化して示す断面図である。非水電解液二次電池１０は、負極側からみて、負極集電体１、負極活物質層２、セパレータ３、正極活物質層４、正極集電体５を、この順に有する積層構造を有している。負極活物質層２と正極活物質層４との間は非水電解液（図示せず）で満たされ、かつセパレータ３で分断されている。セパレータ３は空孔を有し、通常の電池の使用状態では電解液及びイオンをこの空孔により透過しながら正負極間を絶縁する正負極分離膜として機能する。このような構造により、例えばリチウムイオン二次電池であれば、充電時には外部回路を通って負極側に電子（ｅ－）が供給され、同時に電解液を介して正極からリチウムイオン（Ｌｉ＋）が移動してきて負極に蓄積される。一方、放電時には、負極に蓄積されたリチウムイオン（Ｌｉ＋）が電解液を介して正極側に戻され、作動部位６には電子が供給される。図示した例では、作動部位６に電球を採用しており、放電によりこれが点灯するようにされている。
　本発明において、負極集電体１と負極活物質層２とを合わせて負極と称し、正極活物質層４と正極集電体５とを合わせて正極と称している。 FIG. 1 is a cross-sectional view schematically showing the laminated structure of a general non-aqueous electrolyte secondary battery 10, including an operating electrode when operating the battery. The nonaqueous electrolyte secondary battery 10 has a laminated structure including a negative electrode current collector 1, a negative electrode active material layer 2, a separator 3, a positive electrode active material layer 4, and a positive electrode current collector 5 in this order when viewed from the negative electrode side. are doing. The space between the negative electrode active material layer 2 and the positive electrode active material layer 4 is filled with a non-aqueous electrolyte (not shown) and separated by a separator 3. The separator 3 has pores, and functions as a positive and negative electrode separation membrane that insulates between the positive and negative electrodes while allowing electrolyte and ions to pass through the pores during normal use of the battery. With such a structure, for example, in the case of a lithium ion secondary battery, during charging, electrons (e - ) are supplied to the negative electrode side through the external circuit, and at the same time, lithium ions (Li + ) are supplied from the positive electrode through the electrolyte. It moves and accumulates on the negative electrode. On the other hand, during discharging, lithium ions (Li + ) accumulated in the negative electrode are returned to the positive electrode side via the electrolyte, and electrons are supplied to the operating region 6 . In the illustrated example, a light bulb is used as the operating portion 6, and the light bulb is lit by discharge.
In the present invention, the negative electrode current collector 1 and the negative electrode active material layer 2 are collectively referred to as a negative electrode, and the positive electrode active material layer 4 and the positive electrode current collector 5 are collectively referred to as a positive electrode.
　本発明の二次電池は、本発明の電極用組成物を用いて形成された正極活物質層及び負極活物質層の少なくともいずれか１つを具備してなること以外は、電解液（水系電解液、非水電解液）又は固体電解質材料等の電解質、セパレータ等のその他の各部材等は、特に制限されない。これらの材料及び部材等は、通常の二次電池に用いられるものを適宜に適用することができる。また、本発明の二次電池の作製方法についても、本発明の電極用組成物を用いて正極活物質層及び負極活物質層の少なくともいずれか１つを形成すること以外は、通常の方法を適宜に採用することができる。これらの二次電池に通常使用される部材及び作製方法については、例えば、特開２０１６－２０１３０８号公報、特開２００５－１０８８３５号公報、特開２０１２－１８５９３８号公報及び国際公開第２０２０／０６７１０６号等を適宜に参照することができる。
　非水電解液の好ましい形態について、より詳しく説明する。 The secondary battery of the present invention includes an electrolytic solution (aqueous electrolyte There are no particular restrictions on the electrolytes such as liquid, non-aqueous electrolytes) or solid electrolyte materials, and other members such as separators. As these materials and members, those used in ordinary secondary batteries can be used as appropriate. Further, regarding the method for producing the secondary battery of the present invention, a normal method is followed except that at least one of the positive electrode active material layer and the negative electrode active material layer is formed using the electrode composition of the present invention. It can be adopted as appropriate. Regarding the members and manufacturing methods normally used for these secondary batteries, for example, JP2016-201308A, JP2005-108835A, JP2012-185938A, and International Publication No. 2020/067106. etc. can be referred to as appropriate.
A preferred form of the non-aqueous electrolyte will be explained in more detail.
（電解質）
　非水電解液に用いる電解質は周期律表第１族又は第２族に属する金属イオンの塩が好ましい。使用する金属イオンの塩は非水電解液の使用目的により適宜選択される。例えば、リチウム塩、カリウム塩、ナトリウム塩、カルシウム塩、マグネシウム塩等が挙げられ、二次電池等に使用される場合には、出力の観点からリチウム塩が好ましい。非水電解液をリチウムイオン二次電池用電解液として用いる場合には、金属イオンの塩としてリチウム塩を選択すればよい。リチウム塩としては、リチウムイオン二次電池用電解液の電解質に通常用いられるリチウム塩が好ましく、例えば、以下のリチウム塩が挙げられる。 (Electrolytes)
The electrolyte used in the nonaqueous electrolyte is preferably a salt of a metal ion belonging to Group 1 or Group 2 of the periodic table. The metal ion salt used is appropriately selected depending on the intended use of the non-aqueous electrolyte. Examples include lithium salts, potassium salts, sodium salts, calcium salts, magnesium salts, etc. When used in secondary batteries etc., lithium salts are preferred from the viewpoint of output. When a non-aqueous electrolyte is used as an electrolyte for a lithium ion secondary battery, a lithium salt may be selected as the metal ion salt. As the lithium salt, lithium salts commonly used in electrolytes of electrolytes for lithium ion secondary batteries are preferable, and examples thereof include the following lithium salts.
（Ｌ－１）無機リチウム塩：ＬｉＰＦ６、ＬｉＢＦ４、ＬｉＡｓＦ６、ＬｉＳｂＦ６等の無機フッ化物塩、ＬｉＣｌＯ４、ＬｉＢｒＯ４、ＬｉＩＯ４等の過ハロゲン酸塩、ＬｉＡｌＣｌ４等の無機塩化物塩等 (L-1) Inorganic lithium salt: Inorganic fluoride salts such as LiPF 6 , LiBF 4 , LiAsF 6 , LiSbF 6 , perhalates such as LiClO 4 , LiBrO 4 , LiIO 4 , inorganic chloride salts such as LiAlCl 4 etc
（Ｌ－２）含フッ素有機リチウム塩：ＬｉＣＦ３ＳＯ３等のパーフルオロアルカンスルホン酸塩、ＬｉＮ（ＣＦ３ＳＯ２）２、ＬｉＮ（ＣＦ３ＣＦ２ＳＯ２）２、ＬｉＮ（ＦＳＯ２）２、ＬｉＮ（ＣＦ３ＳＯ２）（Ｃ４Ｆ９ＳＯ２）等のフルオロスルホニルイミド塩又はパーフルオロアルカンスルホニルイミド塩、ＬｉＣ（ＣＦ３ＳＯ２）３等のパーフルオロアルカンスルホニルメチド塩、Ｌｉ［ＰＦ５（ＣＦ２ＣＦ２ＣＦ３）］、Ｌｉ［ＰＦ４（ＣＦ２ＣＦ２ＣＦ３）２］、Ｌｉ［ＰＦ３（ＣＦ２ＣＦ２ＣＦ３）３］、Ｌｉ［ＰＦ５（ＣＦ２ＣＦ２ＣＦ２ＣＦ３）］、Ｌｉ［ＰＦ４（ＣＦ２ＣＦ２ＣＦ２ＣＦ３）２］、Ｌｉ［ＰＦ３（ＣＦ２ＣＦ２ＣＦ２ＣＦ３）３］等のパーフルオロアルキルフッ化リン酸塩等 (L-2) Fluorine-containing organic lithium salt: perfluoroalkanesulfonate such as LiCF 3 SO 3 , LiN(CF 3 SO 2 ) 2 , LiN(CF 3 CF 2 SO 2 ) 2 , LiN(FSO 2 ) 2 , fluorosulfonylimide salts or perfluoroalkanesulfonylimide salts such as LiN( CF3SO2 ) ( C4F9SO2 ) , perfluoroalkanesulfonylmethide salts such as LiC( CF3SO2 ) 3 , Li [ PF 5 (CF 2 CF 2 CF 3 )], Li [PF 4 (CF 2 CF 2 CF 3 ) 2 ], Li [PF 3 (CF 2 CF 2 CF 3 ) 3 ], Li [PF 5 (CF 2 CF 2 CF 2 CF 3 )], Li[PF 4 (CF 2 CF 2 CF 2 CF 3 ) 2 ], Li[PF 3 (CF 2 CF 2 CF 2 CF 3 ) 3 ], and other perfluoroalkyl fluorinated phosphoric acids. salt etc.
（Ｌ－３）オキサラトボレート塩：リチウムビス（オキサラト）ボレート、リチウムジフルオロオキサラトボレート等 (L-3) Oxalatoborate salt: lithium bis(oxalato)borate, lithium difluorooxalatoborate, etc.
　これらのなかでも、ＬｉＰＦ６、ＬｉＢＦ４、ＬｉＡｓＦ６、ＬｉＳｂＦ６、ＬｉＣｌＯ４、Ｌｉ（Ｒｆ１ＳＯ３）、ＬｉＮ（Ｒｆ１ＳＯ２）２、ＬｉＮ（ＦＳＯ２）２、又は、ＬｉＮ（Ｒｆ１ＳＯ２）（Ｒｆ２ＳＯ２）が好ましく、ＬｉＰＦ６、ＬｉＢＦ４、ＬｉＮ（Ｒｆ１ＳＯ２）２、ＬｉＮ（ＦＳＯ２）２、又は、ＬｉＮ（Ｒｆ１ＳＯ２）（Ｒｆ２ＳＯ２）がより好ましい。ここで、Ｒｆ１及びＲｆ２はそれぞれパーフルオロアルキル基を示し、炭素数は１～６であることが好ましい。
　なお、非水電解液に用いる電解質は、１種を単独で使用しても、２種以上を任意に組み合わせて使用してもよい。 Among these, LiPF 6 , LiBF 4 , LiAsF 6 , LiSbF 6 , LiClO 4 , Li(R f1 SO 3 ), LiN(R f1 SO 2 ) 2 , LiN(FSO 2 ) 2 , or LiN(R f1 SO 2 )(R f2 SO 2 ) is preferable, and LiPF 6 , LiBF 4 , LiN(R f1 SO 2 ) 2 , LiN(FSO 2 ) 2 or LiN(R f1 SO 2 )(R f2 SO 2 ) is preferable. More preferred. Here, R f1 and R f2 each represent a perfluoroalkyl group, and preferably have 1 to 6 carbon atoms.
Note that the electrolytes used in the non-aqueous electrolyte may be used alone or in any combination of two or more.
　非水電解液における電解質（好ましくは周期律表第１族又は第２族に属する金属のイオン若しくはその金属塩）の塩濃度は非水電解液の使用目的により適宜選択されるが、一般的には非水電解液の全質量中１０～５０質量％であり、好ましくは１５～３０質量％である。モル濃度としては０．５～１．５Ｍが好ましい。なお、イオンの濃度として評価するときには、その好適に適用される金属塩換算で算出すればよい。 The salt concentration of the electrolyte (preferably ions of metals belonging to Group 1 or Group 2 of the periodic table or metal salts thereof) in the non-aqueous electrolyte is selected as appropriate depending on the purpose of use of the non-aqueous electrolyte, but generally is 10 to 50% by mass, preferably 15 to 30% by mass, based on the total mass of the nonaqueous electrolyte. The molar concentration is preferably 0.5 to 1.5M. Note that when evaluating the concentration of ions, it may be calculated in terms of metal salts that are suitably applied.
（非水溶媒）
　非水電解液は、非水溶媒を含有する。
　非水溶媒としては、非プロトン性有機溶媒が好ましく、中でも炭素数が２～１０の非プロトン性有機溶媒がより好ましい。
　このような非水溶媒としては、鎖状若しくは環状のカーボネート化合物、ラクトン化合物、鎖状若しくは環状のエーテル化合物、エステル化合物、ニトリル化合物、アミド化合物、オキサゾリジノン化合物、ニトロ化合物、鎖状又は環状のスルホン若しくはスルホキシド化合物、リン酸エステル化合物が挙げられる。
　なお、エーテル結合、カルボニル結合、エステル結合又はカーボネート結合を有する化合物が好ましい。これらの化合物は置換基を有していてもよく、有していてもよい置換基としては、例えば上述の置換基群Ｔから選ばれる置換基が挙げられる。 (Non-aqueous solvent)
The non-aqueous electrolyte contains a non-aqueous solvent.
As the non-aqueous solvent, aprotic organic solvents are preferred, and aprotic organic solvents having 2 to 10 carbon atoms are particularly preferred.
Such nonaqueous solvents include chain or cyclic carbonate compounds, lactone compounds, chain or cyclic ether compounds, ester compounds, nitrile compounds, amide compounds, oxazolidinone compounds, nitro compounds, chain or cyclic sulfones, or Examples include sulfoxide compounds and phosphate ester compounds.
Note that compounds having an ether bond, a carbonyl bond, an ester bond, or a carbonate bond are preferred. These compounds may have a substituent, and examples of the substituent that may be included include substituents selected from the above-mentioned substituent group T.
　非水溶媒としては、例えば、エチレンカーボネート、フッ化エチレンカーボネート、ビニレンカーボネート、プロピレンカーボネート、ブチレンカーボネート、ジメチルカーボネート、ジエチルカーボネート、エチルメチルカーボネート、メチルプロピルカーボネート、γ－ブチロラクトン、γ－バレロラクトン、１，２－ジメトキシエタン、テトラヒドロフラン、２－メチルテトラヒドロフラン、テトラヒドロピラン、１，３－ジオキソラン、４－メチル－１，３－ジオキソラン、１，３－ジオキサン、１，４－ジオキサン、酢酸メチル、酢酸エチル、プロピオン酸メチル、プロピオン酸エチル、酪酸メチル、イソ酪酸メチル、トリメチル酢酸メチル、トリメチル酢酸エチル、アセトニトリル、グルタロニトリル、アジポニトリル、メトキシアセトニトリル、３－メトキシプロピオニトリル、Ｎ，Ｎ－ジメチルホルムアミド、Ｎ－メチルピロリジノン、Ｎ－メチルオキサゾリジノン、Ｎ，Ｎ’－ジメチルイミダゾリジノン、ニトロメタン、ニトロエタン、スルホラン、リン酸トリメチル、ジメチルスルホキシドあるいはジメチルスルホキシドリン酸等が挙げられる。これらは、１種単独で用いても２種以上を併用してもよい。中でも、エチレンカーボネート、プロピレンカーボネート、ジメチルカーボネート、ジエチルカーボネート、エチルメチルカーボネート及びγ－ブチロラクトンのうちの少なくとも１種が好ましく、エチレンカーボネート又はプロピレンカーボネート等の高粘度（高誘電率）溶媒（例えば、比誘電率ε≧３０）と、ジメチルカーボネート、エチルメチルカーボネート又はジエチルカーボネート等の低粘度溶媒（例えば、粘度≦１ｍＰａ・ｓ）との組み合わせがより好ましい。このような組み合わせの混合溶媒とすることで、電解質塩の解離性及びイオンの移動度が向上する。
　なお、本発明に用いられる非水溶媒は、これらに限定されるものではない。 Examples of the nonaqueous solvent include ethylene carbonate, fluorinated ethylene carbonate, vinylene carbonate, propylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, ethylmethyl carbonate, methylpropyl carbonate, γ-butyrolactone, γ-valerolactone, 1, 2-dimethoxyethane, tetrahydrofuran, 2-methyltetrahydrofuran, tetrahydropyran, 1,3-dioxolane, 4-methyl-1,3-dioxolane, 1,3-dioxane, 1,4-dioxane, methyl acetate, ethyl acetate, propion Methyl acid, ethyl propionate, methyl butyrate, methyl isobutyrate, methyl trimethyl acetate, ethyl trimethyl acetate, acetonitrile, glutaronitrile, adiponitrile, methoxyacetonitrile, 3-methoxypropionitrile, N,N-dimethylformamide, N-methyl Examples include pyrrolidinone, N-methyloxazolidinone, N,N'-dimethylimidazolidinone, nitromethane, nitroethane, sulfolane, trimethyl phosphate, dimethyl sulfoxide, and dimethyl sulfoxide phosphoric acid. These may be used alone or in combination of two or more. Among them, at least one of ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, ethylmethyl carbonate, and γ-butyrolactone is preferable, and high viscosity (high dielectric constant) solvents such as ethylene carbonate or propylene carbonate (for example, dielectric A combination of a low viscosity solvent (for example, viscosity ≦1 mPa·s) such as dimethyl carbonate, ethyl methyl carbonate or diethyl carbonate is more preferred. By using such a combination of mixed solvents, the dissociation property of the electrolyte salt and the mobility of ions are improved.
Note that the nonaqueous solvent used in the present invention is not limited to these.
　本発明の二次電池は、例えば、ノートパソコン、ペン入力パソコン、モバイルパソコン、電子ブックプレーヤー、携帯電話、コードレスフォン子機、ページャー、ハンディーターミナル、携帯ファックス、携帯コピー、携帯プリンター、ヘッドフォンステレオ、ビデオムービー、液晶テレビ、ハンディークリーナー、ポータブルＣＤ、ミニディスク、電気シェーバー、トランシーバー、電子手帳、電卓、携帯テープレコーダー、ラジオ、バックアップ電源、メモリーカード等の電子機器に搭載することができる。また、民生用として、自動車、電動車両、モーター、照明器具、玩具、ゲーム機器、ロードコンディショナー、時計、ストロボ、カメラ、医療機器（ペースメーカー、補聴器、肩もみ機等）等に搭載することができる。さらに、各種軍需用、及び、宇宙用として用いることができる。また、太陽電池と組み合わせることもできる。 The secondary battery of the present invention can be used, for example, in a notebook computer, a pen input computer, a mobile computer, an e-book player, a mobile phone, a cordless phone, a pager, a handy terminal, a mobile fax machine, a mobile copier, a mobile printer, a headphone stereo, a video It can be installed in electronic devices such as movies, LCD TVs, handy cleaners, portable CDs, mini discs, electric shavers, transceivers, electronic notebooks, calculators, portable tape recorders, radios, backup power supplies, and memory cards. In addition, for consumer use, it can be installed in automobiles, electric vehicles, motors, lighting equipment, toys, game equipment, road conditioners, watches, strobes, cameras, medical equipment (pacemakers, hearing aids, shoulder massagers, etc.), etc. Furthermore, it can be used for various military purposes and space purposes. It can also be combined with solar cells.
　実施例に基づき本発明について更に詳細に説明する。なお、本発明は本発明で規定すること以外は、これらの実施例により限定して解釈されるものではない。また、室温とは２５℃を意味する。組成比、配合量比、含有量については、特段の断りのない限り、質量基準を意味する。 The present invention will be explained in more detail based on Examples. Note that the present invention is not to be construed as being limited by these Examples other than what is specified in the present invention. Moreover, room temperature means 25°C. The composition ratio, blending ratio, and content are based on mass unless otherwise specified.
＜実施例Ｉ＞
［水溶性高分子（Ｘ）の合成］
　あらかじめ、アクリルアミド（富士フイルム和光純薬社製）７５．０ｇ、蒸留水７５．０ｇ及びＶＡ－０５７（商品名、富士フイルム和光純薬社製の水溶性アゾ重合開始剤）０．５２ｇを室温で撹拌、混合し、溶液Ａを調製した。
　還流冷却管、ガス導入コックを付した１Ｌ三口フラスコに、蒸留水３３７．５ｇを加えた。流速２００ｍＬ／ｍｉｎにて窒素ガスを６０分間導入した後に、７５℃に昇温した。上記で調製した溶液Ａを、上記１Ｌ三口フラスコ中の蒸留水に１時間かけて滴下した。滴下完了後、７５℃で３時間撹拌を続けた。室温まで冷却し、ポリアクリルアミド（ＰＡＡｍ）の水溶液を得た。得られた水溶液の固形分濃度は１４．０質量％であり、得られたポリアクリルアミドの重量平均分子量（Ｍｗ）は３６００００、分子量分布（Ｍｗ／Ｍｎ）は２．４０であった。 <Example I>
[Synthesis of water-soluble polymer (X)]
In advance, 75.0 g of acrylamide (manufactured by Fuji Film Wako Pure Chemical Industries, Ltd.), 75.0 g of distilled water, and 0.52 g of VA-057 (trade name, water-soluble azo polymerization initiator manufactured by Fuji Film Wako Pure Chemical Industries, Ltd.) were added at room temperature. Stir and mix to prepare solution A.
337.5 g of distilled water was added to a 1 L three-neck flask equipped with a reflux condenser and a gas introduction cock. After introducing nitrogen gas for 60 minutes at a flow rate of 200 mL/min, the temperature was raised to 75°C. Solution A prepared above was added dropwise to the distilled water in the 1 L three-necked flask over 1 hour. After completion of the dropwise addition, stirring was continued at 75° C. for 3 hours. It was cooled to room temperature to obtain an aqueous solution of polyacrylamide (PAAm). The solid content concentration of the obtained aqueous solution was 14.0% by mass, the weight average molecular weight (Mw) of the obtained polyacrylamide was 360000, and the molecular weight distribution (Mw/Mn) was 2.40.
　上記ポリアクリルアミドの合成において、単量体組成を後述の表１又は２のように変更するか、及び／又は、ＭｗとＭｗ／Ｍｎが後述の表１又は２の値になるように重合開始剤の配合量を調整した以外は、上記ポリアクリルアミドの合成と同様にして、表１又は２に記載の水溶性高分子（Ｘ）を合成した。
　上記で調製した水溶性高分子（Ｘ）の水溶液の固形分濃度は、いずれも１４．０質量％であった。また、上記で得られた水溶性高分子（Ｘ）の２０℃における水に対する溶解度は、いずれも１００ｇ／Ｌ－Ｈ２Ｏ以上であった。
　なお、水溶性高分子（Ｘ）の重量平均分子量（Ｍｗ）及び数平均分子量（Ｍｎ）は、上述のようにして測定した。 In the synthesis of the above polyacrylamide, the monomer composition is changed as shown in Table 1 or 2 below, and/or the polymerization initiator is changed so that Mw and Mw/Mn are the values shown in Table 1 or 2 below. The water-soluble polymers (X) shown in Table 1 or 2 were synthesized in the same manner as in the synthesis of the polyacrylamide above, except that the blending amount was adjusted.
The solid content concentration of the aqueous solutions of water-soluble polymers (X) prepared above was 14.0% by mass. Further, the water solubility of the water-soluble polymer (X) obtained above at 20°C was all 100 g/L-H 2 O or more.
The weight average molecular weight (Mw) and number average molecular weight (Mn) of the water-soluble polymer (X) were measured as described above.
［バインダー組成物の調製］
　表１に記載の水溶性高分子（Ｘ）及び水溶性高分子（Ｙ）を含有するバインダー組成物を、以下のようにして調製した。
　６０ｍＬの軟膏容器（馬野化学社製）に、水溶性高分子（Ｘ）の水溶液７．５０ｇ（固形分量１．０５ｇ）、水溶性高分子（Ｙ）の水溶液８．００ｇ（固形分量０．４０ｇ）を加え、あわとり練太郎（商品名、ＴＨＩＮＫＹ社製）を用いて２０００ｒｐｍで４分間攪拌することにより、バインダー組成物を得た。バインダー組成物の固形分濃度は、９．３５質量％であった。 [Preparation of binder composition]
A binder composition containing the water-soluble polymer (X) and water-soluble polymer (Y) listed in Table 1 was prepared as follows.
In a 60 mL ointment container (manufactured by Umano Kagaku Co., Ltd.), add 7.50 g of an aqueous solution of water-soluble polymer (X) (solid content 1.05 g) and 8.00 g of an aqueous solution of water-soluble polymer (Y) (solid content 0.40 g). ) and stirred for 4 minutes at 2000 rpm using Awatori Rentaro (trade name, manufactured by THINKY) to obtain a binder composition. The solid content concentration of the binder composition was 9.35% by mass.
　また、表２に記載の水溶性高分子（Ｘ）、水溶性高分子（Ｙ）及び重合体粒子を含有するバインダー組成物を、以下のようにして調製した。
　６０ｍＬの軟膏容器（馬野化学社製）に、水溶性高分子（Ｘ）の水溶液７．５０ｇ（固形分量１．０５ｇ）、水溶性高分子（Ｙ）の水溶液８．００ｇ（固形分量０．４０ｇ）を加え、あわとり練太郎（商品名、ＴＨＩＮＫＹ社製）を用いて２０００ｒｐｍで４分間分散した。更に、分散した液に重合体粒子２．０９ｇ（液媒体として水を含む、固形分量１．０５ｇ）を加え、あわとり練太郎を用いて２０００ｒｐｍで２分間分散することにより、バインダー組成物を得た。バインダー組成物の固形分濃度は、１４．２質量％であった。 Further, a binder composition containing the water-soluble polymer (X), water-soluble polymer (Y), and polymer particles listed in Table 2 was prepared as follows.
In a 60 mL ointment container (manufactured by Umano Kagaku Co., Ltd.), add 7.50 g of an aqueous solution of water-soluble polymer (X) (solid content 1.05 g) and 8.00 g of an aqueous solution of water-soluble polymer (Y) (solid content 0.40 g). ) was added and dispersed for 4 minutes at 2000 rpm using Awatori Rentaro (trade name, manufactured by THINKY). Furthermore, 2.09 g of polymer particles (containing water as a liquid medium, solid content 1.05 g) were added to the dispersed liquid, and the binder composition was obtained by dispersing for 2 minutes at 2000 rpm using a foamer. Ta. The solid content concentration of the binder composition was 14.2% by mass.
　上記で調製したバインダー組成物について、以下のようにして引張試験を行い、引張弾性率を算出した。得られた結果を、表１及び２にまとめて示す。 The binder composition prepared above was subjected to a tensile test as follows, and the tensile modulus was calculated. The results obtained are summarized in Tables 1 and 2.
（引張試験：バインダー組成物の引張弾性率の算出）
　剥離性のポリエチレンテレフタレート（ＰＥＴ）フィルム（縦５ｃｍ、横０．５ｃｍ、膜厚０．１ｍｍ）に、上記で調製したバインダー組成物を塗布して乾燥させた。ＰＥＴフィルムから、バインダー組成物の塗布膜を剥離し、縦５ｃｍ、横０．５ｃｍ、膜厚０．１００～０．１５０ｍｍのバインダー組成物の塗布膜の試験片を得た。試験片の縦方向において、端から１ｃｍの位置及び他方の端から１ｃｍの位置をそれぞれ治具に固定し、引張試験機（商品名：ＦＧＳ－ＴＶ、日本電産シンポ社製）を用いて引張試験を行った。なお、この試験は２３℃、引張速度５ｍｍ／分で行った。変位に対する荷重を測定した結果から得られる応力－ひずみ曲線の弾性領域の平均値から引張弾性率を算出した。得られた引張弾性率を下記評価ランクに当てはめて評価した。
 
－引張弾性率の評価ランク（重合体粒子を含まない場合）－
　５：６０００ＭＰａ以上
　４：４５００ＭＰａ以上、６０００ＭＰａ未満
　３：３５００ＭＰａ以上、４５００ＭＰａ未満
　２：３０００ＭＰａ以上、３５００ＭＰａ未満
　１：３０００ＭＰａ未満
 
－引張弾性率の評価ランク（重合体粒子を含む場合）－
　５：２５００ＭＰａ以上
　４：２０００ＭＰａ以上、２５００ＭＰａ未満
　３：１５００ＭＰａ以上、２０００ＭＰａ未満
　２：１０００ＭＰａ以上、１５００ＭＰａ未満
　１：１０００ＭＰａ未満 (Tensile test: Calculation of tensile modulus of binder composition)
The binder composition prepared above was applied to a peelable polyethylene terephthalate (PET) film (5 cm long, 0.5 cm wide, 0.1 mm thick) and dried. The coating film of the binder composition was peeled off from the PET film to obtain a test piece of the coating film of the binder composition measuring 5 cm in length, 0.5 cm in width, and 0.100 to 0.150 mm in thickness. In the longitudinal direction of the test piece, a position 1 cm from one end and a position 1 cm from the other end were fixed to a jig, and tensile test was performed using a tensile tester (product name: FGS-TV, manufactured by Nidec-Shimpo Corporation). We conducted a test. Note that this test was conducted at 23° C. and a tensile speed of 5 mm/min. The tensile modulus was calculated from the average value of the elastic region of the stress-strain curve obtained from the results of measuring the load versus displacement. The obtained tensile modulus was evaluated by applying it to the following evaluation rank.

-Evaluation rank of tensile modulus (without polymer particles)-
5: 6000MPa or more 4: 4500MPa or more, less than 6000MPa 3: 3500MPa or more, less than 4500MPa 2: 3000MPa or more, less than 3500MPa 1: Less than 3000MPa
-Evaluation rank of tensile modulus (if polymer particles are included)-
5: 2500MPa or more 4: 2000MPa or more, less than 2500MPa 3: 1500MPa or more, less than 2000MPa 2: 1000MPa or more, less than 1500MPa 1: Less than 1000MPa
［負極用組成物の調製例１］
　表１に記載の水溶性高分子（Ｘ）及び水溶性高分子（Ｙ）を含有する負極用組成物を、以下のようにして調製した。
　６０ｍＬの軟膏容器（馬野化学社製）にカーボンコートされた酸化ケイ素（炭素元素の含有量の割合１．３質量％、平均粒径：５μｍ、大阪チタニウム社製）を１．７８ｇと、黒鉛（商品名：ＭＡＧ－Ｄ、昭和電工マテリアルズ社製）を７．１２ｇと、アセチレンブラック（商品名：デンカブラック、デンカ社製）を０．６０ｇと、水溶性高分子（Ｘ）の水溶液を２．５９ｇ（固形分量０．３６２ｇ）と、水溶性高分子（Ｙ）の水溶液を２．７６ｇ（固形分量０．１３８ｇ）と、蒸留水を３．３３ｇとを加え、あわとり練太郎（商品名、ＴＨＩＮＫＹ社製）を用いて２０００ｒｐｍで６分間分散した。分散した液に蒸留水を０．６９ｇ加え、あわとり練太郎を用いて２０００ｒｐｍで１２分間分散することにより、負極用組成物を得た。負極用組成物の固形分濃度は、５３質量％であった。 [Preparation example 1 of negative electrode composition]
A negative electrode composition containing the water-soluble polymer (X) and water-soluble polymer (Y) listed in Table 1 was prepared as follows.
A 60 mL ointment container (manufactured by Umano Chemical Co., Ltd.) was filled with 1.78 g of carbon-coated silicon oxide (carbon element content: 1.3% by mass, average particle size: 5 μm, manufactured by Osaka Titanium Co., Ltd.) and graphite ( 7.12 g of acetylene black (product name: MAG-D, manufactured by Showa Denko Materials), 0.60 g of acetylene black (product name: Denka Black, manufactured by Denka), and 2 g of an aqueous solution of water-soluble polymer (X). .59 g (solid content 0.362 g), 2.76 g (solid content 0.138 g) of an aqueous solution of water-soluble polymer (Y), and 3.33 g of distilled water, , manufactured by THINKY) for 6 minutes at 2000 rpm. A composition for a negative electrode was obtained by adding 0.69 g of distilled water to the dispersed liquid and dispersing it for 12 minutes at 2000 rpm using a foamer. The solid content concentration of the negative electrode composition was 53% by mass.
［負極用組成物の調製例２］
　また、表２に記載の水溶性高分子（Ｘ）、水溶性高分子（Ｙ）及び重合体粒子を含有する負極用組成物を、以下のようにして調製した。
　６０ｍＬの軟膏容器（馬野化学社製）にカーボンコートされた酸化ケイ素（炭素元素の含有量の割合１．３質量％、平均粒径：５μｍ、大阪チタニウム社製）を１．７８ｇと、黒鉛（商品名：ＭＡＧ－Ｄ、昭和電工マテリアルズ社製）を７．１２ｇと、アセチレンブラック（商品名：デンカブラック、デンカ社製）を０．６０ｇと、水溶性高分子（Ｘ）の水溶液を１．４９ｇ（固形分量０．２０８ｇ）と、水溶性高分子（Ｙ）の水溶液を１．６８ｇ（固形分量０．０８４ｇ）と、蒸留水を５．６ｇとを加え、あわとり練太郎（商品名、ＴＨＩＮＫＹ社製）を用いて２０００ｒｐｍで６分間分散した。分散した液に蒸留水を０．２７ｇ加え、あわとり練太郎を用いて２０００ｒｐｍで１２分間分散した。更に、分散した液に重合体粒子を０．４１ｇ（固形分量０．２０８ｇ）を加え、あわとり練太郎を用いて２０００ｒｐｍで３分間分散することにより、負極用組成物を得た。負極用組成物の固形分濃度は、５３質量％であった。 [Preparation example 2 of negative electrode composition]
In addition, a negative electrode composition containing the water-soluble polymer (X), water-soluble polymer (Y), and polymer particles listed in Table 2 was prepared as follows.
A 60 mL ointment container (manufactured by Umano Chemical Co., Ltd.) was filled with 1.78 g of carbon-coated silicon oxide (carbon element content: 1.3% by mass, average particle size: 5 μm, manufactured by Osaka Titanium Co., Ltd.) and graphite ( 7.12 g of acetylene black (product name: MAG-D, manufactured by Showa Denko Materials), 0.60 g of acetylene black (product name: Denka Black, manufactured by Denka), and 1 aqueous solution of water-soluble polymer (X). .49 g (solid content 0.208 g), 1.68 g (solid content 0.084 g) of an aqueous solution of water-soluble polymer (Y), and 5.6 g of distilled water were added. , manufactured by THINKY) for 6 minutes at 2000 rpm. 0.27 g of distilled water was added to the dispersed liquid, and the mixture was dispersed for 12 minutes at 2000 rpm using a foaming machine. Further, 0.41 g (solid content: 0.208 g) of polymer particles was added to the dispersed liquid, and the mixture was dispersed for 3 minutes at 2000 rpm using a foaming Rentaro to obtain a negative electrode composition. The solid content concentration of the negative electrode composition was 53% by mass.
　上記で調製した負極用組成物から得られる負極シートを備えた二次電池について、以下のようにして放電容量維持率を測定し、サイクル特性を評価した。得られた結果を、表１及び２にまとめて示す。 Regarding the secondary battery equipped with the negative electrode sheet obtained from the negative electrode composition prepared above, the discharge capacity retention rate was measured as follows, and the cycle characteristics were evaluated. The results obtained are summarized in Tables 1 and 2.
［非水電解液二次電池（２０３２型コイン電池）の作製１］
　上記で調製した負極用組成物を厚み２０μｍの銅箔上に、アプリケーターにより塗布し、８０℃１時間で乾燥させた。その後、プレス機を用いて、加圧した後に１５０℃真空で６時間乾燥することで、負極活物質層の厚さが２５μｍの負極シートを得た。この負極シートから直径１３．０ｍｍの円板を切り出し、負極の形成に用いた。
　リチウム箔（厚み５０μｍ、１４．５ｍｍφ）、ポリプロピレン製セパレータ（厚み２５μｍ、１６．０ｍｍφ）の順番に重ね、ＬｉＰＦ６のエチレンカーボネート／エチルメチルカーボネート（体積比１対２）電解液（濃度１Ｍ）の２００μＬをセパレータに浸み込ませた。セパレータの上にさらに上記電解液を２００μＬ浸み込ませて、円板状の負極シートを負極活物質層面がセパレータに接するようにして重ねた。その後、２０３２型コインケースをかしめることで、非水電解液二次電池（Ｌｉ箔－セパレータ－負極活物質層－銅箔からなる積層体を有する電池）を作製した。 [Preparation 1 of non-aqueous electrolyte secondary battery (2032 type coin battery)]
The negative electrode composition prepared above was applied onto a 20 μm thick copper foil using an applicator and dried at 80° C. for 1 hour. Thereafter, the material was pressurized using a press and then dried in vacuum at 150° C. for 6 hours to obtain a negative electrode sheet with a negative electrode active material layer having a thickness of 25 μm. A disk with a diameter of 13.0 mm was cut out from this negative electrode sheet and used to form a negative electrode.
Lithium foil (thickness 50 μm, 14.5 mmφ) and polypropylene separator (thickness 25 μm, 16.0 mmφ) were stacked in this order, and LiPF 6 ethylene carbonate/ethyl methyl carbonate (volume ratio 1:2) electrolyte solution (concentration 1M) was layered. 200 μL was soaked into the separator. Further, 200 μL of the above electrolyte solution was soaked onto the separator, and a disk-shaped negative electrode sheet was stacked so that the negative electrode active material layer surface was in contact with the separator. Thereafter, the 2032 type coin case was caulked to produce a nonaqueous electrolyte secondary battery (a battery having a laminate consisting of Li foil, separator, negative electrode active material layer, and copper foil).
（サイクル特性の評価）
　上記のようにして作製した各二次電池の放電容量維持率を、充放電評価装置：ＴＯＳＣＡＴ－３０００（商品名、東洋システム社製）により測定した。充電は、Ｃレート（Ｃａｐａｃｉｔｙレート）０．２Ｃ（５時間で満充電になる速度）で電池電圧が０．０２Ｖに達するまで行った。放電は、Ｃレート０．２Ｃで電池電圧が１．５Ｖに達するまで行った。この充電１回と放電１回とを充放電１サイクルとして３サイクル充放電を繰り返して、二次電池を初期化した。
　初期化後の二次電池について、充電を０．５Ｃで０．０２Ｖに達するまで行い、放電を０．５Ｃで１．５Ｖに達するまで行った。この充電１回と放電１回を充放電１サイクルとして、８０サイクル充放電を繰り返すことでサイクル特性の評価を行った。
　初期化後１サイクル目の放電容量（初期放電容量）を１００％としたときに、８０サイクル充放電後の放電容量維持率（［初期放電容量］に対する［８０サイクル充放電後の放電容量］の割合）を算出し、下記評価ランクに当てはめサイクル特性を評価した。
　なお、充放電はいずれも２５℃で行った。
 
－サイクル特性の評価ランク－（重合体粒子を含まない場合）
　５：　９０％以上
　４：　８８％以上、９０％未満
　３：　８６％以上、８８％未満
　２：　８４％以上、８６％未満
　１：　８４％未満
 
－サイクル特性の評価ランク－（重合体粒子を含む場合）
　５：９３％以上
　４：９１％以上、９３％未満
　３：８９％以上、９１％未満
　２：８７％以上、８９％未満
　１：８７％未満 (Evaluation of cycle characteristics)
The discharge capacity retention rate of each secondary battery produced as described above was measured using a charge/discharge evaluation device: TOSCAT-3000 (trade name, manufactured by Toyo System Co., Ltd.). Charging was carried out at a C rate (capacity rate) of 0.2 C (a rate at which the battery was fully charged in 5 hours) until the battery voltage reached 0.02 V. Discharging was performed at a C rate of 0.2C until the battery voltage reached 1.5V. The secondary battery was initialized by repeating three cycles of charging and discharging, with one charging and one discharging as one charging/discharging cycle.
The secondary battery after initialization was charged at 0.5C until reaching 0.02V, and discharged at 0.5C until it reached 1.5V. The cycle characteristics were evaluated by repeating 80 cycles of charging and discharging, with one charging and one discharging being defined as one charging/discharging cycle.
When the discharge capacity at the first cycle after initialization (initial discharge capacity) is taken as 100%, the discharge capacity retention rate after 80 cycles of charging and discharging (discharge capacity after 80 cycles of charging and discharging against [initial discharge capacity]) The cycle characteristics were evaluated by calculating the ratio) and applying it to the evaluation rank below.
Note that both charging and discharging were performed at 25°C.

-Evaluation rank of cycle characteristics- (when not containing polymer particles)
5: 90% or more 4: 88% or more, less than 90% 3: 86% or more, less than 88% 2: 84% or more, less than 86% 1: Less than 84%
-Evaluation rank of cycle characteristics- (if polymer particles are included)
5: 93% or more 4: 91% or more, less than 93% 3: 89% or more, less than 91% 2: 87% or more, less than 89% 1: Less than 87%
Figure JPOXMLDOC01-appb-T000006
Figure JPOXMLDOC01-appb-T000006
Figure JPOXMLDOC01-appb-T000007
Figure JPOXMLDOC01-appb-T000007
Figure JPOXMLDOC01-appb-T000008
Figure JPOXMLDOC01-appb-T000008
Figure JPOXMLDOC01-appb-T000009
Figure JPOXMLDOC01-appb-T000009
Figure JPOXMLDOC01-appb-T000010
Figure JPOXMLDOC01-appb-T000010
＜表の注＞
「－」：該当する成分を含有しないことを示す。
（水溶性高分子（Ｘ））
　ＡＡｍ：アクリルアミド
　ＨＥＡ：２－ヒドロキシエチルアクリレート
　ＡＮ：アクリロニトリル
　ＡＡ：アクリル酸
　ＨＥＡＡ：Ｎ－（２－ヒドロキシエチル）アクリルアミド
　ＮＶＰ：Ｎ－ビニル－２－ピロリドン
Ｍｗ：水溶性高分子（Ｘ）の重量平均分子量、有効数字３桁
Ｍｎ：水溶性高分子（Ｘ）の数平均分子量
Ｍｗ／Ｍｎ：水溶性高分子（Ｘ）の分子量分布
組成比：水溶性高分子（Ｘ）を構成する単量体由来の構成成分の合計に占める各単量体由来の構成成分の割合を示し、単位は質量％である。
（水溶性高分子（Ｙ））
　ＣＭＣ：カルボキシメチルセルロース（ダイセルミライズ社製）
　ＨＥＣ：ヒドロキシエチルセルロース（ダイセルミライズ社製）
　ＨＰＣ：ヒドロキシプロピルセルロース（日本曹達社製）
　ＨＰＭＣ：ヒドロキシプロピルメチルセルロース（信越化学工業社製）
　カラギナン：三晶社製
　キサンタンガム：三晶社製
Ｍｗ：水溶性高分子（Ｙ）の重量平均分子量、有効数字３桁
Ｙ／Ｘ：水溶性高分子（Ｘ）の重量平均分子量（Ｍｗ）に対する水溶性高分子（Ｙ）の重量平均分子量（Ｍｗ）の比、有効数字３桁
（重合体粒子）
　重合体粒子１：特開２０１２－２１２５３７号公報の段落番号００３８に記載の共重合体ラテックス１の作製例に従って合成した。
　重合体粒子２：特開２０１１－１７１１８１号公報の段落番号００４４に記載の共重合体ラテックス（Ｂ－２）の合成例に従って合成した。
　重合体粒子３：国際公開第２０２０／２２６０３５号の段落番号０１３４に記載の重合体（Ａ）の調製例に従って合成した。
　重合体粒子４：特開２０２０－１２３５９０号公報の段落番号０１４１に記載の粒子状重合体Ｚ１の調製例に従って合成した。
　なお、重合体粒子１～４はいずれも、２０℃において水に対する溶解度は１０ｇ／Ｌ－Ｈ２Ｏ未満であった。
　比較例８の引張弾性率の欄における「測定不可」とは、バインダー組成物が脆く測定に用いる試験片を作製することができず、引張弾性率を測定できなかったこと意味する。 <Table notes>
"-": Indicates that the corresponding component is not contained.
(Water-soluble polymer (X))
AAm: Acrylamide HEA: 2-hydroxyethyl acrylate AN: Acrylonitrile AA: Acrylic acid HEAA: N-(2-hydroxyethyl)acrylamide NVP: N-vinyl-2-pyrrolidone Mw: Weight average molecular weight of water-soluble polymer (X) , 3 significant figures Mn: Number average molecular weight of water-soluble polymer (X) Mw/Mn: Molecular weight distribution composition ratio of water-soluble polymer (X): Origin of monomers constituting water-soluble polymer (X) The ratio of the constituent components derived from each monomer to the total constituent components is shown, and the unit is mass %.
(Water-soluble polymer (Y))
CMC: Carboxymethyl cellulose (manufactured by Daicel Millize)
HEC: Hydroxyethylcellulose (manufactured by Daicel Millize)
HPC: Hydroxypropylcellulose (manufactured by Nippon Soda Co., Ltd.)
HPMC: Hydroxypropyl methylcellulose (manufactured by Shin-Etsu Chemical Co., Ltd.)
Carrageenan: Manufactured by Sansho Co., Ltd. Xanthan gum: Manufactured by Sansho Co., Ltd. Mw: Weight average molecular weight of water-soluble polymer (Y), 3 significant figures Y/X: Water solubility with respect to weight average molecular weight (Mw) of water-soluble polymer (X) Ratio of weight average molecular weight (Mw) of polymer (Y), 3 significant figures (polymer particles)
Polymer particles 1: Synthesized according to the production example of copolymer latex 1 described in paragraph number 0038 of JP-A-2012-212537.
Polymer particles 2: Synthesized according to the synthesis example of copolymer latex (B-2) described in paragraph number 0044 of JP-A-2011-171181.
Polymer particles 3: Synthesized according to the preparation example of polymer (A) described in paragraph number 0134 of International Publication No. 2020/226035.
Polymer particles 4: Synthesized according to the preparation example of particulate polymer Z1 described in paragraph number 0141 of JP-A-2020-123590.
Note that all of the polymer particles 1 to 4 had a solubility in water of less than 10 g/L-H 2 O at 20°C.
"Unmeasurable" in the tensile modulus column of Comparative Example 8 means that the binder composition was too brittle to prepare a test piece for measurement, and the tensile modulus could not be measured.
　表１及び２から以下のことが分かる。
　比較例１～６、１１～２１の負極用組成物は水溶性高分子（Ｘ）の重量平均分子量に対する水溶性高分子（Ｙ）の重量平均分子量の比（Ｙ／Ｘ）が本発明で規定する範囲外である点で、いずれも本発明の電極用組成物でない。また、比較例７の負極用組成物は水溶性高分子（Ｙ）を含有せず、比較例８の負極用組成物は水溶性高分子（Ｘ）を含有せず、比較例９及び１０の負極用組成物は水溶性高分子（Ｘ）の欄に記載する水溶性高分子が一般式（Ｂ－２）で表される構成成分を１０質量％しか含有しない点で、いずれも本発明の電極用組成物ではない。これらの比較例１～２１の負極用組成物に用いたバインダー組成物の引張弾性率はいずれも小さく、また、これらの比較例１～２１の負極用組成物を用いて作製した負極シートを有する二次電池はいずれも、サイクル特性に劣っていた。
　これに対して、実施例１～７４の負極用組成物はいずれも本発明の電極用組成物である。これらの実施例１～７４の負極用組成物に用いたバインダー組成物の引張弾性率はいずれも大きく、また、実施例１～７４の負極用組成物を用いて作製した負極シートを有する二次電池はいずれも、優れたサイクル特性を示すことが分かった。 The following can be seen from Tables 1 and 2.
In the negative electrode compositions of Comparative Examples 1 to 6 and 11 to 21, the ratio (Y/X) of the weight average molecular weight of the water-soluble polymer (Y) to the weight average molecular weight of the water-soluble polymer (X) is defined by the present invention. None of them are electrode compositions of the present invention in that they are outside the range. Further, the negative electrode composition of Comparative Example 7 does not contain the water-soluble polymer (Y), the negative electrode composition of Comparative Example 8 does not contain the water-soluble polymer (X), and the negative electrode composition of Comparative Example 9 and 10 does not contain the water-soluble polymer (X). The negative electrode compositions meet the requirements of the present invention in that the water-soluble polymer described in the column of water-soluble polymer (X) contains only 10% by mass of the component represented by general formula (B-2). It is not a composition for electrodes. The tensile modulus of the binder compositions used in the negative electrode compositions of these Comparative Examples 1 to 21 were all small, and the negative electrode sheets produced using the negative electrode compositions of these Comparative Examples 1 to 21 were All secondary batteries had poor cycle characteristics.
On the other hand, the negative electrode compositions of Examples 1 to 74 are all electrode compositions of the present invention. The tensile moduli of the binder compositions used in the negative electrode compositions of Examples 1 to 74 were all large, and the secondary It was found that all the batteries exhibited excellent cycling characteristics.
＜実施例II＞
［負極用組成物の調製例３］
　表１に記載の実施例１～４、９～１５、１９～２１、２４～３２、３４、３６～４２及び４６～５０、並びに、比較例１、２、４及び７～１０の負極用組成物について、負極活物質の種類をカーボンコートされた酸化ケイ素（炭素元素の含有量の割合１．３質量％、平均粒径：５μｍ、大阪チタニウム社製）から下記のようにして作製した金属ドープ活物質に変更した以外は、上述の［負極用組成物の調製例１］と同様にして、負極用組成物を調製した。
［負極用組成物の調製例４］
　表２に記載の実施例５１、５３、５４、５６、５７、５９、６０、６２、６３、６５、６６、６８、６９、７１、７２及び７４、並びに、比較例１４～２１の負極用組成物について、負極活物質の種類をカーボンコートされた酸化ケイ素（炭素元素の含有量の割合１．３質量％、平均粒径：５μｍ、大阪チタニウム社製）から下記のようにして作製した金属ドープ活物質に変更した以外は、上述の［負極用組成物の調製例２］と同様にして、負極用組成物を調製した。
　なお、上記の負極層組成物の調製例３及び４では、１つの実施例につき、リチウムドープ及びカーボンコートの両方が施された酸化ケイ素（ＬｉＳｉＯＣ）を含有する負極用組成物ａ、ニッケルドープ及びカーボンコートの両方が施された酸化ケイ素（ＮｉＳｉＯＣ）を含有する負極用組成物ｂ、及び、チタンドープ及びカーボンコートの両方が施された酸化ケイ素（ＴｉＳｉＯＣ）を含有する負極用組成物ｃの３種類の負極用組成物を調製したことになる。このことは、比較例についても同様である。 <Example II>
[Preparation example 3 of negative electrode composition]
Negative electrode compositions of Examples 1 to 4, 9 to 15, 19 to 21, 24 to 32, 34, 36 to 42, and 46 to 50 and Comparative Examples 1, 2, 4, and 7 to 10 listed in Table 1 Regarding the material, the negative electrode active material was a metal dope prepared from carbon-coated silicon oxide (carbon element content: 1.3% by mass, average particle size: 5 μm, manufactured by Osaka Titanium Co., Ltd.) as follows. A negative electrode composition was prepared in the same manner as in [Preparation Example 1 of Negative Electrode Composition] described above, except that the active material was changed.
[Preparation example 4 of negative electrode composition]
Negative electrode compositions of Examples 51, 53, 54, 56, 57, 59, 60, 62, 63, 65, 66, 68, 69, 71, 72 and 74 and Comparative Examples 14 to 21 listed in Table 2 Regarding the material, the negative electrode active material was a metal dope prepared from carbon-coated silicon oxide (carbon element content: 1.3% by mass, average particle size: 5 μm, manufactured by Osaka Titanium Co., Ltd.) as follows. A negative electrode composition was prepared in the same manner as in [Preparation Example 2 of Negative Electrode Composition] above, except that the active material was changed.
In addition, in Preparation Examples 3 and 4 of the above-mentioned negative electrode layer composition, in one example, negative electrode composition a containing both lithium-doped and carbon-coated silicon oxide (LiSiOC), nickel-doped and Negative electrode composition b containing silicon oxide (NiSiOC) coated with both carbon and negative electrode composition c containing silicon oxide (TiSiOC) coated with both titanium and carbon. This means that different types of negative electrode compositions have been prepared. This also applies to the comparative examples.
［金属ドープ活物質の作製］
（１）リチウムドープ及びカーボンコートの両方が施された酸化ケイ素の作製
　特開２０２２－１２１５８２号公報の実施例１－１に記載の方法と同様にして、リチウムドープ及びカーボンコートの両方が施された酸化ケイ素（ＬｉＳｉＯＣ）を作製した。具体的には以下のようにして行った。
　金属ケイ素と二酸化ケイ素を混合した原料（気化出発材）を反応炉へ設置し、１０Ｐａの真空度の雰囲気中で気化させたものを吸着板上に堆積させ、十分に冷却した後、堆積物（酸化ケイ素）を取出しボールミルで粉砕した。粒径を調整した後、熱ＣＶＤ（ｔｈｅｍａｌ　ｃｈｅｍｉｃａｌ　ｖａｐｏｒ　ｄｅｐｏｓｉｔｉｏｎ）を行うことでカーボンコートを形成した。熱ＣＶＤの際には、粉砕した酸化ケイ素を、窒化珪素製トレイに仕込んだ後、雰囲気を保持できる処理炉内に静置した。次にアルゴンガスを流入し、処理炉内をアルゴン置換した後、メタン－アルゴン混合ガスを２ＮＬ／ｍｉｎ流入しつつ３００℃／ｈｒの昇温速度で昇温し、６００～１，１００℃の温度で、３～１０時間保持することにより熱ＣＶＤを施し、カーボンコートされた酸化ケイ素（ＳｉＯＣ）を得た。保持終了後、降温を開始し、室温到達後、粉末を回収した。
　続いて、カーボンコートされた酸化ケイ素に対して酸化還元法によりリチウムをドープし改質を行った。まず、カーボンコートされた酸化ケイ素を、リチウム片とナフタレンとをテトラヒドロフラン（以下、ＴＨＦと呼称する）に溶解させた溶液（溶液Ａ）に浸漬した。この溶液Ａは、具体的には、ＴＨＦ溶媒にナフタレンを０．２ｍｏｌ／Ｌの濃度で溶解させたのちに、このＴＨＦ溶媒とナフタレンとの混合液に対して１０質量％の質量分のリチウム片を加えることで作製した。また、カーボンコートされた酸化ケイ素を浸漬する際の溶液Ａの温度は２０℃とし、浸漬時間は２０時間とした。その後、固形分を濾取した。以上の処理によりカーボンコートされた酸化ケイ素にリチウムをドープした。得られた固形分をアルゴン雰囲気下６００℃で２４時間熱処理を行い、Ｌｉ化合物の安定化を行った。このようにして、カーボンコートされた酸化ケイ素の改質を行い、リチウムドープ及びカーボンコートの両方が施された酸化ケイ素（ＬｉＳｉＯＣ）を得た。なお、炭素元素の含有量の割合は３質量％、ＬｉＳｉＯＣ粒子の平均粒径（体積基準のメジアン径Ｄ５０）は６．７μｍであった。 [Preparation of metal doped active material]
(1) Production of silicon oxide with both lithium dope and carbon coating Both lithium dope and carbon coat were applied in the same manner as the method described in Example 1-1 of JP 2022-121582A. A silicon oxide (LiSiOC) was prepared. Specifically, it was performed as follows.
A raw material (vaporized starting material) that is a mixture of metallic silicon and silicon dioxide is placed in a reactor, and the vaporized material is deposited on an adsorption plate in a vacuum atmosphere of 10 Pa. After cooling sufficiently, the deposit ( Silicon oxide) was taken out and ground in a ball mill. After adjusting the particle size, a carbon coat was formed by thermal CVD (thermal chemical vapor deposition). During thermal CVD, pulverized silicon oxide was placed in a silicon nitride tray, and then placed in a processing furnace capable of maintaining an atmosphere. Next, argon gas was introduced to replace the inside of the processing furnace with argon, and then the temperature was raised at a rate of 300°C/hr while a methane-argon mixed gas was introduced at a rate of 2NL/min until the temperature reached 600 to 1,100°C. Then, thermal CVD was performed by holding the sample for 3 to 10 hours to obtain carbon-coated silicon oxide (SiOC). After the holding was completed, the temperature started to decrease, and after reaching room temperature, the powder was collected.
Subsequently, the carbon-coated silicon oxide was doped with lithium by a redox method to perform modification. First, carbon-coated silicon oxide was immersed in a solution (solution A) in which lithium pieces and naphthalene were dissolved in tetrahydrofuran (hereinafter referred to as THF). Specifically, this solution A is prepared by dissolving naphthalene in a THF solvent at a concentration of 0.2 mol/L, and then dissolving lithium pieces in a mass amount of 10% by mass with respect to the mixed solution of the THF solvent and naphthalene. It was created by adding. Further, the temperature of solution A when immersing the carbon-coated silicon oxide was 20° C., and the immersion time was 20 hours. Thereafter, the solid content was collected by filtration. Through the above treatment, the carbon-coated silicon oxide was doped with lithium. The obtained solid content was heat treated at 600° C. for 24 hours in an argon atmosphere to stabilize the Li compound. In this way, the carbon-coated silicon oxide was modified to obtain silicon oxide (LiSiOC) that was both lithium-doped and carbon-coated. Note that the content ratio of carbon element was 3% by mass, and the average particle size (volume-based median diameter D50) of the LiSiOC particles was 6.7 μm.
（２）ニッケルドープ及びカーボンコートの両方が施された酸化ケイ素、並びにチタンドープ及びカーボンコートの両方が施された酸化ケイ素の作製
　特開２０２１－１５００７７号公報の実施例に記載の負極用粉末材料の作製と同様にして、ニッケルドープ及びカーボンコートの両方が施された酸化ケイ素（ＮｉＳｉＯＣ）並びにチタンドープ及びカーボンコートの両方が施された酸化ケイ素（ＴｉＳｉＯＣ）を作製した。具体的には以下のようにして行った。
（ｉ）Ｓｉ合金の作製
　後記表Ａに示すＳｉ合金組成となるように各原料を秤量した。秤量した各原料を高周波誘導炉を用いて加熱、溶解し、合金溶湯とした。ガスアトマイズ法により、上記得られた合金溶湯から粉末状のＳｉ合金を作製した。なお、合金溶湯作製時およびガスアトマイズ時の雰囲気はアルゴン雰囲気とした。また、ガスアトマイズ時には、噴霧チャンバ内を棒状に落下する合金溶湯に対して、高圧（４ＭＰａ）のアルゴンガスを噴き付けた。得られた粉末を篩いを用いて２５μｍ以下に分級したものを、以降のステップでＳｉ合金として用いた。
（ii）メカニカルミリング処理の準備
　ステンレス製のポット中に、金属ボール（サイズ：Φ３／８ｉｎｃｈ、材質：ＳＵＪ２（ＪＩＳ（日本工業規格）　Ｇ　４８０５（２０１９）規定の高炭素クロム軸受鋼鋼材ＳＵＪ２））３０個とともに、後記表Ａに示す混合割合となるように、Ｓｉ合金と、金属酸化物としてのＳｉＯ２粉末とを投入した。例えば目的物を１０ｇ作製する場合、Ｓｉ合金９．５ｇとＳｉＯ２粉末０．５ｇとを投入した。投入後、ポット内部の雰囲気をＡｒガスで置換した。
（iii）メカニカルミリング処理
　ポットを遊星ボールミル装置（フリッチュ社製、Ｐ－５／４）にセットし、３００ｒｐｍ、１５０時間の条件で処理して得られた混合粉末を、以降のステップで金属元素をドープされたケイ素系材料（ニッケルドープされた酸化ケイ素（ＮｉＳｉＯ）又はチタンドープされた酸化ケイ素（ＴｉＳｉＯ））として用いた。
（iv）金属元素をドープされたケイ素系材料へのカーボンコート処理
　金属元素をドープされたケイ素系材料（ＮｉＳｉＯ又はＴｉＳｉＯ）に、熱ＣＶＤを行うことでカーボンコートを形成した。熱ＣＶＤの際には、メカニカルミリング処理後の金属元素をドープされたケイ素系材料を、窒化珪素製トレイに仕込んだ後、雰囲気を保持できる処理炉内に静置した。次にアルゴンガスを流入し、処理炉内をアルゴン置換した後、メタン－アルゴン混合ガスを２ＮＬ／ｍｉｎ流入しつつ３００℃／ｈｒの昇温速度で昇温し、６００～１，１００℃の温度で、３～１０時間保持することにより炭素膜の熱ＣＶＤを施し、金属元素のドープ及びカーボンコートの両方が施されたケイ素系材料（ニッケルドープ及びカーボンコートの両方が施された酸化ケイ素（ＮｉＳｉＯＣ）並びにチタンドープ及びカーボンコートの両方が施された酸化ケイ素（ＴｉＳｉＯＣ））を得た。保持終了後、降温を開始し、室温到達後、粉末を回収した。
　なお、炭素元素の含有量の割合は３質量％、ＮｉＳｉＯＣ粒子及びＴｉＳｉＯＣ粒子の平均粒径（体積基準のメジアン径Ｄ５０）は共に７μｍであった。 (2) Production of silicon oxide that is both nickel-doped and carbon coated, and silicon oxide that is titanium-doped and carbon coated Powder material for negative electrodes described in Examples of JP-A-2021-150077 Silicon oxide (NiSiOC) that was both nickel-doped and carbon-coated and silicon oxide (TiSiOC) that was both titanium-doped and carbon-coated were fabricated in the same manner as in the fabrication of . Specifically, it was performed as follows.
(i) Production of Si alloy Each raw material was weighed so as to have the Si alloy composition shown in Table A below. Each weighed raw material was heated and melted using a high frequency induction furnace to obtain a molten alloy. A powdered Si alloy was produced from the obtained molten alloy by a gas atomization method. Note that the atmosphere during the preparation of the molten alloy and during gas atomization was an argon atmosphere. Furthermore, during gas atomization, high-pressure (4 MPa) argon gas was sprayed onto the molten alloy falling in a rod shape inside the spray chamber. The obtained powder was classified to 25 μm or less using a sieve and used as a Si alloy in subsequent steps.
(ii) Preparation for mechanical milling process Place a metal ball (size: Φ3/8 inch, material: SUJ2 (high carbon chromium bearing steel SUJ2 according to JIS (Japanese Industrial Standards) G 4805 (2019)) in a stainless steel pot. Along with the 30 pieces, Si alloy and SiO 2 powder as a metal oxide were added at a mixing ratio shown in Table A below. For example, when producing 10 g of a target object, 9.5 g of Si alloy and 0.5 g of SiO 2 powder were charged. After charging, the atmosphere inside the pot was replaced with Ar gas.
(iii) Mechanical milling process The pot was set in a planetary ball mill (manufactured by Fritsch, P-5/4), and the mixed powder obtained by processing at 300 rpm and 150 hours was treated with metal elements in the subsequent steps. A doped silicon-based material (nickel-doped silicon oxide (NiSiO) or titanium-doped silicon oxide (TiSiO)) was used.
(iv) Carbon coating treatment on a silicon-based material doped with a metal element A carbon coat was formed on a silicon-based material (NiSiO or TiSiO) doped with a metal element by performing thermal CVD. During thermal CVD, the silicon-based material doped with a metal element after mechanical milling was placed in a silicon nitride tray, and then placed in a processing furnace capable of maintaining an atmosphere. Next, argon gas was introduced to replace the inside of the processing furnace with argon, and then the temperature was raised at a rate of 300°C/hr while a methane-argon mixed gas was introduced at a rate of 2NL/min until the temperature reached 600 to 1,100°C. The carbon film is thermally CVDed by holding it for 3 to 10 hours to form a silicon-based material doped with a metal element and coated with carbon (silicon oxide (NiSiOC) coated with both nickel dope and carbon). ) and both titanium-doped and carbon-coated silicon oxide (TiSiOC)) were obtained. After the holding was completed, the temperature started to decrease, and after reaching room temperature, the powder was collected.
Note that the content ratio of carbon element was 3% by mass, and the average particle diameter (volume-based median diameter D50) of both NiSiOC particles and TiSiOC particles was 7 μm.
Figure JPOXMLDOC01-appb-T000011
Figure JPOXMLDOC01-appb-T000011
＜表Ａの注＞
ＮｉＳｉＯ：ニッケルドープされた酸化ケイ素
ＴｉＳｉＯ：チタンドープされた酸化ケイ素
合金組成：金属元素のドープされたケイ素系材料（ＮｉＳｉＯ又はＴｉＳｉＯ）を得る際に投入したＳｉ合金及びＳｉＯ２粉末の合計１００質量％に占めるＳｉ合金中の各金属元素の割合を示し、単位は質量％であり、合金組成の合計は９５質量％である。
　また、混合割合とは、金属元素のドープされたケイ素系材料（ＮｉＳｉＯ又はＴｉＳｉＯ）を得る際に投入したＳｉ合金及びＳｉＯ２粉末の合計に占める各成分（Ｓｉ合金又はＳｉＯ２粉末）の割合を示し、単位は質量％である。 <Notes to Table A>
NiSiO: Nickel-doped silicon oxide TiSiO: Titanium-doped silicon oxide alloy Composition: Total of 100% by mass of Si alloy and SiO 2 powder input when obtaining a silicon-based material doped with a metal element (NiSiO or TiSiO) It shows the proportion of each metal element in the Si alloy, the unit is mass %, and the total alloy composition is 95 mass %.
In addition, the mixing ratio refers to the proportion of each component (Si alloy or SiO 2 powder) in the total amount of Si alloy and SiO 2 powder that are input when obtaining a silicon-based material doped with a metal element (NiSiO or TiSiO). The unit is mass %.
［非水電解液二次電池（２０３２型コイン電池）の作製２］
　上述の［非水電解液二次電池（２０３２型コイン電池）の作製１］において、負極用組成物として上記負極用組成物の調製例３又は４で調製した負極用組成物を用いた以外は同様にして、非水電解液二次電池を作製した。 [Preparation of non-aqueous electrolyte secondary battery (2032 type coin battery) 2]
In the above [Preparation 1 of nonaqueous electrolyte secondary battery (2032 type coin battery)], except that the negative electrode composition prepared in Preparation Example 3 or 4 of the negative electrode composition was used as the negative electrode composition. A non-aqueous electrolyte secondary battery was produced in the same manner.
（サイクル特性の評価）
　上記のようにして作製した各二次電池の放電容量維持率を、上述の（サイクル特性の評価）に記載の方法により測定し、初期化後１サイクル目の放電容量（初期放電容量）を１００％としたときに、８０サイクル充放電後の放電容量維持率（［初期放電容量］に対する［８０サイクル充放電後の放電容量］の割合）を算出し、下記評価ランクに当てはめサイクル特性を評価した。得られた結果を、表３及び４にまとめて示す。
　なお、実施例及び比較例のいずれの負極用組成物を用いた場合においても、金属ドープ活物質（ＬｉＳｉＯＣ、ＮｉＳｉＯＣ又はＴｉＳｉＯＣ）の違いによって、サイクル特性の評価ランクに違いはなかった。そのため、表３及び４においては、金属ドープ活物質の異なる３種類の負極用組成物ａ、ｂ及びｃを用いた場合の評価結果を、まとめて１つの欄に記載した。例えば、実施例１－ａｂｃの欄のサイクル特性の評価「４」とは、ＬｉＳｉＯＣを含有する実施例１の負極用組成物ａ、ＮｉＳｉＯＣを含有する実施例１の負極用組成物ｂ、及び、ＴｉＳｉＯＣを含有する実施例１の負極用組成物ｃを用いた場合のサイクル特性の評価が、いずれも「４」であることを意味する。
 
－サイクル特性の評価ランク－（重合体粒子を含まない場合）
　５：　９２％以上
　４：　９０％以上、９２％未満
　３：　８８％以上、９０％未満
　２：　８６％以上、８８％未満
　１：　８６％未満
 
－サイクル特性の評価ランク－（重合体粒子を含む場合）
　５：９５％以上
　４：９３％以上、９５％未満
　３：９１％以上、９３％未満
　２：８９％以上、９１％未満
　１：８９％未満 (Evaluation of cycle characteristics)
The discharge capacity retention rate of each secondary battery produced as described above was measured by the method described in (Evaluation of cycle characteristics) above, and the discharge capacity at the first cycle after initialization (initial discharge capacity) was measured at 100%. %, the discharge capacity retention rate after 80 cycles of charging and discharging (ratio of [discharge capacity after 80 cycles of charging and discharging] to [initial discharge capacity]) was calculated, and the cycle characteristics were evaluated by applying it to the following evaluation rank. . The obtained results are summarized in Tables 3 and 4.
In addition, even when using any of the negative electrode compositions of Examples and Comparative Examples, there was no difference in the evaluation rank of cycle characteristics depending on the difference in metal doped active material (LiSiOC, NiSiOC, or TiSiOC). Therefore, in Tables 3 and 4, the evaluation results when three types of negative electrode compositions a, b, and c having different metal-doped active materials were used were collectively listed in one column. For example, the cycle characteristic evaluation "4" in the column of Example 1-abc means negative electrode composition a of Example 1 containing LiSiOC, negative electrode composition b of Example 1 containing NiSiOC, and This means that the evaluation of cycle characteristics when using the negative electrode composition c of Example 1 containing TiSiOC is "4" in all cases.

-Evaluation rank of cycle characteristics- (when not containing polymer particles)
5: 92% or more 4: 90% or more, less than 92% 3: 88% or more, less than 90% 2: 86% or more, less than 88% 1: Less than 86%
-Evaluation rank of cycle characteristics- (if polymer particles are included)
5: 95% or more 4: 93% or more, less than 95% 3: 91% or more, less than 93% 2: 89% or more, less than 91% 1: Less than 89%
Figure JPOXMLDOC01-appb-T000012
Figure JPOXMLDOC01-appb-T000012
Figure JPOXMLDOC01-appb-T000013
Figure JPOXMLDOC01-appb-T000013
Figure JPOXMLDOC01-appb-T000014
Figure JPOXMLDOC01-appb-T000014
Figure JPOXMLDOC01-appb-T000015
Figure JPOXMLDOC01-appb-T000015
＜表の注＞
　表中の水溶性高分子（Ｘ）、水溶性高分子（Ｙ）、Ｙ／Ｘ及び重合体粒子の欄の記載については、前述の表１及び２の注における記載と同義である。
　引張弾性率の欄の記載は、バインダー組成物の引張弾性率の評価結果であるため、前述の表１及び２における引張弾性率の評価結果に対応する。 <Table notes>
The descriptions in the columns of water-soluble polymer (X), water-soluble polymer (Y), Y/X, and polymer particles in the table are synonymous with the descriptions in the notes to Tables 1 and 2 above.
The description in the tensile modulus column is the evaluation result of the tensile modulus of the binder composition, and therefore corresponds to the evaluation result of the tensile modulus in Tables 1 and 2 above.
　表３及び４から以下のことがわかる。
　負極活物質として、カーボンコートされた酸化ケイ素に代えて、リチウムドープ及びカーボンコートの両方が施された酸化ケイ素、ニッケルドープ及びカーボンコートの両方が施された酸化ケイ素、或いはチタンドープ及びカーボンコートの両方が施された酸化ケイ素のうちのいずれの負極活物質を用いた場合においても、サイクル特性の評価は、表１及び２に記載のカーボンコートされた酸化ケイ素を用いた場合と同様の傾向を示すことが分かった。
　すなわち、比較例１、２、４、７～１０及び１４～２１の負極用組成物ａ、ｂ及びｃを用いて作製した負極シートを有する二次電池に対して、実施例１～４、９～１５、１９～２１、２４～３２、３４、３６～４２、４６～５０、５１、５３、５４、５６、５７、５９、６０、６２、６３、６５、６６、６８、６９、７１、７２及び７４の負極用組成物ａ、ｂ及びｃを用いて作製した負極シートを有する二次電池はいずれも、優れたサイクル特性を示すことが分かった。 The following can be seen from Tables 3 and 4.
As the negative electrode active material, instead of carbon-coated silicon oxide, silicon oxide doped with both lithium and carbon, silicon oxide doped with nickel and carbon coated, or silicon oxide doped with titanium and carbon coated. Regardless of which negative electrode active material of silicon oxide coated with both is used, the evaluation of cycle characteristics shows the same tendency as when using carbon coated silicon oxide described in Tables 1 and 2. I found out that it shows.
That is, for secondary batteries having negative electrode sheets prepared using negative electrode compositions a, b, and c of Comparative Examples 1, 2, 4, 7 to 10, and 14 to 21, Examples 1 to 4, and 9 ~15, 19-21, 24-32, 34, 36-42, 46-50, 51, 53, 54, 56, 57, 59, 60, 62, 63, 65, 66, 68, 69, 71, 72 It was found that all of the secondary batteries having negative electrode sheets prepared using the negative electrode compositions a, b, and c of No. 74 exhibited excellent cycle characteristics.
　本発明をその実施態様とともに説明したが、我々は特に指定しない限り我々の発明を説明のどの細部においても限定しようとするものではなく、添付の請求の範囲に示した発明の精神と範囲に反することなく幅広く解釈されるべきであると考える。 Although the invention has been described in conjunction with embodiments thereof, we do not intend to limit our invention in any detail in the description unless otherwise specified and contrary to the spirit and scope of the invention as set forth in the appended claims. I believe that it should be interpreted broadly without any restrictions.
　本願は、２０２２年７月２９日に日本国で特許出願された特願２０２２－１２２２３５及び２０２２年１０月１４日に日本国で特許出願された特願２０２２－１６５８８５に基づく優先権を主張するものであり、これらはここに参照してその内容を本明細書の記載の一部として取り込む。 This application claims priority based on Japanese Patent Application No. 2022-122235, which was filed in Japan on July 29, 2022, and Patent Application No. 2022-165885, which was filed in Japan on October 14, 2022. and these are hereby incorporated by reference and their contents are incorporated as part of the description of this specification.
１０　非水電解液二次電池
　１　負極集電体
　２　負極活物質層
　３　セパレータ
　４　正極活物質層
　５　正極集電体
　６　作動部位（電球） 10 Nonaqueous electrolyte secondary battery 1 Negative electrode current collector 2 Negative electrode active material layer 3 Separator 4 Positive electrode active material layer 5 Positive electrode current collector 6 Operating part (light bulb)

Claims (18)

  1. 　水溶性高分子（Ｘ）及び水溶性高分子（Ｙ）を含み、前記水溶性高分子（Ｘ）は、下記一般式（Ｂ－２）で表される構成成分を２０質量％以上含む重合体であり、前記水溶性高分子（Ｘ）の重量平均分子量に対する前記水溶性高分子（Ｙ）の重量平均分子量の比が０．３００～１０．０である、二次電池用バインダー組成物。
    Figure JPOXMLDOC01-appb-C000001
     　一般式（Ｂ－２）中、Ｒ２１～Ｒ２３は水素原子、シアノ基又は炭素数１～６のアルキル基を示し、Ｒ２４は水素原子、アシル基、ヒドロキシ基、フェニル基又はカルボキシ基を示し、Ｌ２１は単結合、炭素数１～１６のアルキレン基、炭素数６～１２のアリーレン基、酸素原子、硫黄原子、カルボニル基若しくはイミノ基、又はこれらを組み合わせた連結基を示す。＊は前記水溶性高分子（Ｘ）の主鎖中に組み込まれるための結合部位を示す。     A polymer containing a water-soluble polymer (X) and a water-soluble polymer (Y), where the water-soluble polymer (X) contains 20% by mass or more of a constituent represented by the following general formula (B-2). A binder composition for a secondary battery, wherein the ratio of the weight average molecular weight of the water-soluble polymer (Y) to the weight average molecular weight of the water-soluble polymer (X) is 0.300 to 10.0.
    Figure JPOXMLDOC01-appb-C000001
     In the general formula (B-2), R 21 to R 23 represent a hydrogen atom, a cyano group, or an alkyl group having 1 to 6 carbon atoms, and R 24 represents a hydrogen atom, an acyl group, a hydroxy group, a phenyl group, or a carboxy group. and L 21 represents a single bond, an alkylene group having 1 to 16 carbon atoms, an arylene group having 6 to 12 carbon atoms, an oxygen atom, a sulfur atom, a carbonyl group, an imino group, or a linking group combining these. * indicates a binding site for incorporation into the main chain of the water-soluble polymer (X).
  2. 　前記水溶性高分子（Ｘ）中、前記一般式（Ｂ－２）で表される構成成分の含有量が８０質量％以上である、請求項１に記載の二次電池用バインダー組成物。 The binder composition for a secondary battery according to claim 1, wherein the content of the component represented by the general formula (B-2) in the water-soluble polymer (X) is 80% by mass or more.
  3. 　前記一般式（Ｂ－２）で表される構成成分が（メタ）アクリルアミド成分を含む、請求項１に記載の二次電池用バインダー組成物。 The binder composition for a secondary battery according to claim 1, wherein the component represented by the general formula (B-2) includes a (meth)acrylamide component.
  4. 　前記水溶性高分子（Ｘ）が、アクリロニトリル成分及びＮ－ビニル－２－ピロリドン成分の少なくとも１種を、更に含む重合体である、請求項１に記載の二次電池用バインダー組成物。 The binder composition for a secondary battery according to claim 1, wherein the water-soluble polymer (X) is a polymer further containing at least one of an acrylonitrile component and an N-vinyl-2-pyrrolidone component.
  5. 　前記水溶性高分子（Ｘ）の重量平均分子量が１００００～１００００００である、請求項１～４のいずれか１項に記載の二次電池用バインダー組成物。 The binder composition for a secondary battery according to any one of claims 1 to 4, wherein the water-soluble polymer (X) has a weight average molecular weight of 10,000 to 1,000,000.
  6. 　前記水溶性高分子（Ｘ）の分子量分布が５．０以下である、請求項１に記載の二次電池用バインダー組成物。 The binder composition for a secondary battery according to claim 1, wherein the water-soluble polymer (X) has a molecular weight distribution of 5.0 or less.
  7. 　前記水溶性高分子（Ｙ）が多糖類である、請求項１～４のいずれか１項に記載の二次電池用バインダー組成物。 The binder composition for a secondary battery according to any one of claims 1 to 4, wherein the water-soluble polymer (Y) is a polysaccharide.
  8. 　前記水溶性高分子（Ｙ）が、カルボキシメチルセルロース、ヒドロキシエチルセルロース、ヒドロキシプロピルセルロース及びキサンタンガムの少なくとも１種を含む、請求項７に記載の二次電池用バインダー組成物。 The binder composition for a secondary battery according to claim 7, wherein the water-soluble polymer (Y) contains at least one of carboxymethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, and xanthan gum.
  9. 　前記水溶性高分子（Ｙ）の重量平均分子量が１０００００～５０００００である、請求項１～４のいずれか１項に記載の二次電池用バインダー組成物。 The binder composition for a secondary battery according to any one of claims 1 to 4, wherein the water-soluble polymer (Y) has a weight average molecular weight of 100,000 to 500,000.
  10. 　重合体粒子を含む、請求項１に記載の二次電池用バインダー組成物。 The binder composition for a secondary battery according to claim 1, comprising polymer particles.
  11. 　前記重合体粒子を構成する重合体が、共役ジエン成分、エチレン性不飽和カルボン酸成分、シアノ基含有エチレン性モノマー成分及び芳香族ビニルモノマー成分の少なくとも１種を含む重合体である、請求項１０に記載の二次電池用バインダー組成物。 10. The polymer constituting the polymer particles is a polymer containing at least one of a conjugated diene component, an ethylenically unsaturated carboxylic acid component, a cyano group-containing ethylenic monomer component, and an aromatic vinyl monomer component. A binder composition for secondary batteries as described in .
  12. 　水を含む、請求項１～４のいずれか１項に記載の二次電池用バインダー組成物。 The binder composition for a secondary battery according to any one of claims 1 to 4, which contains water.
  13. 　周期律表第１族又は第２族に属する金属のイオンの挿入放出が可能な活物質を含む、請求項１に記載の二次電池用バインダー組成物。 The binder composition for a secondary battery according to claim 1, comprising an active material capable of inserting and releasing ions of metals belonging to Group 1 or Group 2 of the Periodic Table.
  14. 　前記活物質がケイ素系活物質を含む、請求項１３に記載の二次電池用バインダー組成物。 The binder composition for a secondary battery according to claim 13, wherein the active material includes a silicon-based active material.
  15. 　請求項１３又は１４に記載の二次電池用バインダー組成物を用いて形成された層を有する電極シート。 An electrode sheet having a layer formed using the binder composition for secondary batteries according to claim 13 or 14.
  16. 　正極活物質層及び負極活物質層の少なくとも１つの層が、請求項１３又は１４に記載の二次電池用バインダー組成物を用いて形成された層である、二次電池。 A secondary battery, wherein at least one of the positive electrode active material layer and the negative electrode active material layer is a layer formed using the binder composition for a secondary battery according to claim 13 or 14.
  17. 　請求項１３又は１４に記載の二次電池用バインダー組成物を用いて電極活物質層を形成することを含む、電極シートの製造方法。 A method for manufacturing an electrode sheet, comprising forming an electrode active material layer using the binder composition for a secondary battery according to claim 13 or 14.
  18. 　請求項１７に記載の製造方法により得られた電極シートを二次電池の電極として組み込むことを含む、二次電池の製造方法。 A method for manufacturing a secondary battery, comprising incorporating an electrode sheet obtained by the manufacturing method according to claim 17 as an electrode of the secondary battery.
PCT/JP2023/027794 2022-07-29 2023-07-28 Binder composition for secondary battery, electrode sheet and secondary battery, and method for producing electrode sheet and secondary battery WO2024024951A1 (en)

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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2014222601A (en) * 2013-05-13 2014-11-27 三菱レイヨン株式会社 Binder resin for nonaqueous secondary battery negative electrode, slurry composition for nonaqueous secondary battery negative electrode, negative electrode for nonaqueous secondary battery, and nonaqueous secondary battery
JP2019526693A (en) * 2016-08-17 2019-09-19 四川茵地▲樂▼科技有限公司 Acrylonitrile copolymer binder and its application in lithium ion batteries
JP2020087777A (en) * 2018-11-28 2020-06-04 トヨタ自動車株式会社 Negative electrode

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2014222601A (en) * 2013-05-13 2014-11-27 三菱レイヨン株式会社 Binder resin for nonaqueous secondary battery negative electrode, slurry composition for nonaqueous secondary battery negative electrode, negative electrode for nonaqueous secondary battery, and nonaqueous secondary battery
JP2019526693A (en) * 2016-08-17 2019-09-19 四川茵地▲樂▼科技有限公司 Acrylonitrile copolymer binder and its application in lithium ion batteries
JP2020087777A (en) * 2018-11-28 2020-06-04 トヨタ自動車株式会社 Negative electrode

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