Classifications

• • 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
  • H01M4/621—Binders
  • H01M4/622—Binders being polymers
• • 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
  • C08F220/00—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
  • C08F220/02—Monocarboxylic acids having less than ten carbon atoms; Derivatives thereof
  • C08F220/04—Acids; Metal salts or ammonium salts thereof
  • C08F220/06—Acrylic acid; Methacrylic acid; Metal salts or ammonium salts thereof
• • 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
  • C08L101/02—Compositions of unspecified macromolecular compounds characterised by the presence of specified groups, e.g. terminal or pendant functional groups
  • C08L101/06—Compositions of unspecified macromolecular compounds characterised by the presence of specified groups, e.g. terminal or pendant functional groups containing oxygen atoms
  • C08L101/08—Carboxyl groups
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L69/00—Compositions of polycarbonates; Compositions of derivatives of polycarbonates
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M10/00—Secondary cells; Manufacture thereof
  • H01M10/05—Accumulators with non-aqueous electrolyte
  • H01M10/052—Li-accumulators
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M10/00—Secondary cells; Manufacture thereof
  • H01M10/05—Accumulators with non-aqueous electrolyte
  • H01M10/052—Li-accumulators
  • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M10/00—Secondary cells; Manufacture thereof
  • H01M10/05—Accumulators with non-aqueous electrolyte
  • H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
  • H01M10/0564—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of organic materials only
  • H01M10/0565—Polymeric materials, e.g. gel-type or solid-type
• • 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
  • H01M4/131—Electrodes based on mixed oxides or hydroxides, or on mixtures of oxides or hydroxides, e.g. LiCoOx
• • 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
  • H01M4/136—Electrodes based on inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy
• • 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
  • H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
• • 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
  • H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
  • H01M4/5825—Oxygenated metallic salts or polyanionic structures, e.g. borates, phosphates, silicates, olivines
• • 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
• • 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
  • C08F2810/00—Chemical modification of a polymer
  • C08F2810/20—Chemical modification of a polymer leading to a crosslinking, either explicitly or inherently
• • 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
  • C08F2810/00—Chemical modification of a polymer
  • C08F2810/50—Chemical modification of a polymer wherein the polymer is a copolymer and the modification is taking place only on one or more of the monomers present in minority
• • 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
  • H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
  • H01M2004/028—Positive electrodes
• • 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 disclosure relates to a binder for electrodes, a composition for forming an electrode mixture layer, an electrode for lithium ion secondary batteries, and a lithium ion secondary battery.
• lithium ion secondary batteries As secondary batteries, various power storage devices such as nickel-metal hydride secondary batteries, lithium-ion secondary batteries, and electric double layer capacitors have been put into practical use. Among them, lithium ion secondary batteries are used in a wide range of applications because of their high energy density and battery capacity.
• a lithium-ion secondary battery is a secondary battery that has a negative electrode, a positive electrode, and an electrolyte, and charges and discharges by moving lithium ions between the two electrodes through the electrolyte.
• an organic electrolytic solution is mainly used as the electrolyte.
• using a solid electrolyte instead of an organic electrolyte has been proposed as a technique for eliminating concerns about leakage of the electrolyte and short-circuiting inside the battery due to overcharge/overdischarge.
• the polymer solid electrolyte has the advantage that it is possible to obtain a highly flexible and flexible all-solid lithium ion secondary battery compared to the inorganic solid electrolyte, and the inner part of the battery derived from the interface between the active material and the electrolyte. It has the advantage of low resistance.
• the electrodes of lithium-ion secondary batteries generally have a current collector made of metal foil, and an electrode mixture layer is arranged on the surface of the current collector.
• the electrode mixture layer is formed by binding an active material with an electrode binder (see, for example, Patent Document 1).
• Patent Document 1 polyvinylidene fluoride (PVDF) is used as an electrode binder (binder), and an electrode formed by a slurry in which an active material and PVDF are dispersed in N-methyl-2-pyrrolidone (NMP).
• PVDF polyvinylidene fluoride
• NMP N-methyl-2-pyrrolidone
• PVDF is used as an electrode binder for producing an electrode of a lithium ion secondary battery containing a polymer solid electrolyte
• an NMP solution containing PVDF and an active material is used to produce a lithium ion secondary battery.
• a main object of the present invention is to provide a water-based electrode binder capable of producing a secondary battery.
• a lithium ion secondary battery electrode binder containing a polymer solid electrolyte which is a carboxyl group-containing polymer or a salt thereof, and has a 5% by mass aqueous solution viscosity of 10,000 mPa ⁇ s or more at 25°C.
• the polymer (A) contains a structural unit derived from a crosslinkable monomer, and the content of the structural unit derived from the crosslinkable monomer in the polymer (A) is equal to the crosslinked
• the polymer (A) contains a structural unit derived from an ethylenically unsaturated monomer having a carboxyl group, and the ethylenically unsaturated monomer having the carboxyl group in the polymer (A)
• the binder for electrodes according to any one of [1] to [3], wherein the structural units derived from are 50% by mass or more of the total structural units of the polymer (A).
• a composition for forming an electrode mixture layer of a lithium ion secondary battery containing a polymer solid electrolyte comprising the electrode binder of any one of [1] to [8] and an active material.
• a composition for forming an electrode mixture layer [10] The composition for forming an electrode mixture layer of [9], wherein the active material is lithium iron phosphate.
• a lithium ion secondary battery comprising the lithium ion secondary battery electrode of [12].
• an electrode binder containing a polymer (A) which is a carboxyl group-containing polymer or a salt thereof and has a 5% by mass aqueous solution viscosity at 25° C. of 10,000 mPa ⁇ s or more an electrode with good surface smoothness and low internal resistance can be produced. Also, a lithium ion secondary battery having a high initial battery capacity and exhibiting good cycle characteristics can be produced. Furthermore, since the polymer (A) is soluble or dispersible in water, it is possible to reduce the use of organic solvents and reduce the environmental load.
• (meth)acryl means acryl and/or methacryl
• (meth)acrylate means acrylate and/or methacrylate
• the electrode binder of the present disclosure is used for producing an electrode (more specifically, an electrode mixture layer) of a lithium ion secondary battery containing a polymer solid electrolyte, and the active materials contained in the electrode mixture layer It has the function of adhering
• the electrode binder of the present disclosure contains a polymer (A) which is a carboxyl group-containing polymer or a salt thereof and has a 5% by mass aqueous solution viscosity of 10,000 mPa ⁇ s or more at 25°C.
• the polymer (A) is a group represented by "--COOH” and/or "[ --COO- ] n R n+ " (where R n+ is a counterion of the carboxyl group and n is an integer of 1 or more ( It is not particularly limited as long as it preferably has 1 or 2).
• Examples of the polymer (A) include polymers having a plurality of “—COOH” and/or “[—COO ⁇ ] n R n+ ”, and ethylenically unsaturated monomers having a carboxyl group (hereinafter referred to as “ A polymer mainly composed of structural units derived from "carboxylic acid monomer” can be preferably used.
• carboxylic acid monomers include (meth)acrylic acid, itaconic acid, crotonic acid, maleic acid, fumaric acid, citraconic acid, cinnamic acid, monohydroxyethyl succinate (meth)acrylate, and ⁇ -carboxy-caprolactone.
• the carboxylic acid monomer is preferably (meth)acrylic acid.
• the polymer (A) contains a structural unit derived from (meth)acrylic acid, and an alkylene carbonate group-containing polymer is used as a polymer component constituting a polymer solid electrolyte of a lithium ion secondary battery, It is preferable in that the adhesion between the electrode and the polymer solid electrolyte can be improved, thereby improving the cycle characteristics.
• examples of counter ions (R n+ ) for the carboxyl group include lithium ion, sodium ion, potassium ion, magnesium ion and calcium ion. Among these, lithium ion, sodium ion or potassium ion is preferred, and lithium ion is more preferred.
• the polymer (A) is a lithium salt of a carboxyl group-containing polymer, it is preferable in that the electrode resistance can be lowered.
• the proportion of structural units derived from carboxylic acid monomers is preferably 50% by mass or more, more preferably 60% by mass or more, relative to all structural units constituting the polymer (A). , more preferably 70% by mass or more, even more preferably 80% by mass or more, and even more preferably 90% by mass or more.
• the ratio of structural units derived from carboxylic acid monomers in the polymer (A) is within the above range, when the solid polymer electrolyte contains an alkylene carbonate group-containing polymer, the adhesion between the electrode and the solid polymer electrolyte is improved. It is suitable in that the property can be made higher.
• the carboxylic acid monomers constituting the polymer (A) may be of one type or two or more types.
• the method for obtaining the polymer (A) is not limited to the method using a carboxylic acid monomer.
• the polymer (A) may be obtained by hydrolyzing after polymerizing a (meth)acrylate monomer.
• the polymer (A) is obtained by a method of treating with a strong alkali, a method of reacting a polymer having a hydroxyl group with an acid anhydride, or the like. You may get
• the viscosity of an aqueous solution containing 5% by mass of polymer (A) at 25°C is 10,000 mPa ⁇ s or more.
• a relatively high-viscosity carboxyl group-containing polymer that satisfies the above-mentioned viscosity range as the electrode binder, the dispersibility of the active material is enhanced, thereby improving the surface smoothness of the electrode.
• a crosslinked polymer can be preferably used as the polymer (A) in that the property-improving effect can be enhanced.
• the viscosity of the aqueous solution containing the polymer (A) at a concentration of 5% by mass (5% by mass aqueous solution) at 25° C. is preferably 15,000 mPa s or more from the viewpoint of increasing the surface smoothness of the electrode. ,000 mPa s or more, more preferably 20,000 mPa s or more, even more preferably 25,000 mPa s or more, and even more preferably 30,000 mPa s or more. preferable.
• the viscosity of the aqueous solution containing the polymer (A) is a value measured using a Brookfield viscometer under conditions of a rotor speed of 12 rpm and 25°C. The details of the measurement method follow the method described in the examples below.
• the upper limit of the viscosity of the 5% by mass aqueous solution of the polymer (A) at 25° C. is not particularly limited.
• a value measured under conditions of 6 rpm and 25°C is 1,000,000 mPa s or less, preferably 900,000 mPa s or less, more preferably 800,000 mPa s or less, and still more preferably 700,000 mPa s. It is below.
• the method for producing the crosslinked polymer is not particularly limited.
• Examples of the method for producing the crosslinked polymer include the following method (1) and method (2).
• a monomer having a crosslinkable functional group hereinafter also referred to as a "crosslinkable monomer”
• a monomer different from the crosslinkable monomer and capable of being copolymerized with the crosslinkable monomer A method of copolymerizing a monomer (hereinafter also referred to as a "non-crosslinkable monomer”) (2) Synthesizing a polymer having a reactive functional group, and if necessary, adding a cross-linking agent to cross-link
• the method (1) is preferable because the operation is simple and the degree of cross-linking can be easily controlled.
• crosslinkable monomer an ethylenically unsaturated monomer having a crosslinkable functional group can be preferably used.
• crosslinkable monomers include polyfunctional polymerizable monomers having two or more ethylenically unsaturated groups, and self-crosslinkable crosslinkable functional groups (e.g., hydrolyzable silyl groups, etc.). Examples thereof include self-crosslinking monomers.
• polyfunctional polymerizable monomers include polyfunctional (meth)acrylate compounds, polyfunctional alkenyl compounds, compounds having both a (meth)acryloyl group and an alkenyl group, and the like.
• the ethylenically unsaturated monomer having a crosslinkable functional group is an alkenyl group-containing compound (polyfunctional alkenyl compound, (meth)acryloyl group and alkenyl group) because it is easy to obtain a uniform crosslinked structure. compounds) are preferred, and polyfunctional alkenyl compounds are more preferred.
• polyfunctional alkenyl compounds include polyfunctional allyl ether compounds such as trimethylolpropane diallyl ether, trimethylolpropane triallyl ether, pentaerythritol diallyl ether, pentaerythritol triallyl ether, tetraallyloxyethane, and polyallyl saccharose; polyfunctional allyl compounds such as diallyl phthalate; and polyfunctional vinyl compounds such as divinylbenzene.
• polyfunctional allyl ether compounds such as trimethylolpropane diallyl ether, trimethylolpropane triallyl ether, pentaerythritol diallyl ether, pentaerythritol triallyl ether, tetraallyloxyethane, and polyallyl saccharose
• polyfunctional allyl compounds such as diallyl phthalate
• polyfunctional vinyl compounds such as divinylbenzene.
• Compounds having both a (meth)acryloyl group and an alkenyl group include allyl (meth)acrylate, isopropenyl (meth)acrylate, butenyl (meth)acrylate, pentenyl (meth)acrylate, and (meth)acrylic acid.
• alkenyl group-containing (meth)acrylic acid compounds such as 2-(2-vinyloxyethoxy)ethyl.
• polyfunctional allyl ether compounds having a plurality of allyl ether groups in the molecule are particularly preferred.
• self-crosslinking monomers include hydrolyzable silyl group-containing vinyl monomers.
• hydrolyzable silyl group-containing vinyl monomers include vinylsilanes such as vinyltrimethoxysilane, vinyltriethoxysilane, vinylmethyldimethoxysilane, and vinyldimethylmethoxysilane; trimethoxysilylpropyl (meth)acrylate; Silyl group-containing (meth)acrylic acid esters such as triethoxysilylpropyl (meth)acrylate and methyldimethoxysilylpropyl (meth)acrylate; trimethoxysilylpropyl vinyl ether, vinyl trimethoxysilylundecanoate and the like.
• the amount of the structural unit derived from the crosslinkable monomer in the polymer (A) is a monomer other than the crosslinkable monomer. It is preferably 0.05 parts by mass or more and 5.0 parts by mass or less with respect to 100 parts by mass of the total amount of the structural units derived from the body (that is, the non-crosslinkable monomer).
• the ratio of the structural unit derived from the crosslinkable monomer is 0.05 parts by mass or more, the effect of improving the dispersibility of the active material in the electrode can be sufficiently obtained, and it is 5.0 parts by mass or less. is preferable in that a lithium ion secondary battery with better cycle characteristics can be obtained.
• the amount of the structural unit derived from the crosslinkable monomer in the polymer (A) is 0.1 parts by mass or more with respect to 100 parts by mass of the total amount of structural units derived from the non-crosslinkable monomer. It is preferably 0.2 parts by mass or more, and even more preferably 0.3 parts by mass or more.
• the total amount of structural units derived from non-crosslinkable monomers is preferably 4.0 parts by mass or less, and 3.5 parts by mass.
• the crosslinkable monomers constituting the polymer (A) may be of one type or two or more types.
• a carboxylic acid monomer is included in the non-crosslinkable monomer.
• the amount of structural units derived from crosslinkable monomers in the polymer (A) is 0.001 mol% or more and 2.5 mol% with respect to the total amount of structural units derived from non-crosslinkable monomers.
• the following are preferable.
• the amount of structural units derived from crosslinkable monomers is more preferably 0.01 mol% or more, more preferably 0.03 mol% or more, relative to the total amount of structural units derived from non-crosslinkable monomers. It is more preferably 0.05 mol % or more, even more preferably 0.10 mol % or more.
• the upper limit of the amount of structural units derived from a crosslinkable monomer it is more preferably 2.0 mol% or less with respect to the total amount of structural units derived from a non-crosslinkable monomer, and 1.5 mol. % or less, even more preferably 1.0 mol % or less, and even more preferably 0.50 mol % or less.
• the polymer (A) is a structural unit derived from a monomer different from the carboxylic acid monomer and the crosslinkable monomer (hereinafter, "other monomer") within the range that does not impair the effects of the present disclosure. may further have as other monomers, ethylenically unsaturated monomers can be preferably used, for example, (meth) acrylic acid alkyl esters, (meth) acrylic acid aliphatic cyclic esters, Aromatic esters, (meth)acrylic acid alkoxyalkyl esters, (meth)acrylic acid hydroxyalkyl esters, polyalkylene glycol mono(meth)acrylates, and the like can be mentioned.
• (meth)acrylic acid alkyl esters such as methyl (meth)acrylate, ethyl (meth)acrylate, isopropyl (meth)acrylate, n-propyl (meth)acrylate, and (meth)acrylic acid.
• examples include n-butyl acid, isobutyl (meth)acrylate, tert-butyl (meth)acrylate, hexyl (meth)acrylate and 2-ethylhexyl (meth)acrylate.
• aliphatic cyclic esters of (meth)acrylic acid include cyclohexyl (meth)acrylate, methylcyclohexyl (meth)acrylate, tert-butylcyclohexyl (meth)acrylate, cyclododecyl (meth)acrylate, Examples include isobornyl (meth)acrylate, adamantyl (meth)acrylate, dicyclopentenyl (meth)acrylate and dicyclopentanyl (meth)acrylate.
• aromatic esters of (meth)acrylic acid include phenyl (meth)acrylate, benzyl (meth)acrylate, phenoxymethyl (meth)acrylate, 2-phenoxyethyl (meth)acrylate and (meth)acrylate. and 3-phenoxypropyl acrylate.
• (meth)acrylate alkoxyalkyl esters include methoxyethyl (meth)acrylate, ethoxyethyl (meth)acrylate, n-propoxyethyl (meth)acrylate, n-butoxyethyl (meth)acrylate, Methoxypropyl (meth)acrylate, ethoxypropyl (meth)acrylate, n-propoxypropyl (meth)acrylate, n-butoxypropyl (meth)acrylate, methoxybutyl (meth)acrylate, ethoxy (meth)acrylate Butyl, n-propoxybutyl (meth)acrylate and n-butoxybutyl (meth)acrylate.
• (meth)acrylic acid hydroxyalkyl esters include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, and 2-hydroxypropyl (meth)acrylate. -hydroxybutyl, 3-hydroxybutyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate.
• Polyalkylene glycol mono(meth)acrylates include polyethylene glycol mono(meth)acrylate, polypropylene glycol mono(meth)acrylate and polyethylene glycol-polypropylene glycol mono(meth)acrylate.
• the content of the structural unit derived from the other monomer is, with respect to all structural units constituting the polymer (A), 60% by mass or less is preferable, 50% by mass or less is more preferable, and 40% by mass or less is even more preferable.
• Other monomers constituting the polymer (A) may be of one type or two or more types.
• a commercially available product can also be used as the crosslinked polymer.
• Such commercially available products include, for example, trade names of Junron (registered trademark) PW-120, Junron PW-121, Junron PW-312S (manufactured by Toagosei Co., Ltd.), Carbopol 934P NF, Carbopol 981, Carbopol Ultraz10. , Carbopol Ultrez 30 (manufactured by Lubrizol) and the like.
• the weight-average molecular weight (Mw) of the high-molecular-weight polymer enhances the dispersibility of the active material in the electrode mixture layer and enhances the surface smoothness of the electrode. Therefore, it is preferably 500,000 or more, more preferably 800,000 or more, still more preferably 1,000,000 or more, and even more preferably 1,500,000 or more. From the viewpoint of handleability, Mw of the high molecular weight polymer is preferably 50 million or less, more preferably 30 million or less, and still more preferably 10 million or less.
• the molecular weight of the high-molecular-weight polymer is a polystyrene-equivalent value measured by gel permeation chromatography (GPC) using tetrahydrofuran as an eluent after the carboxyl group is methylated with trimethylsilyldiazomethane.
• the polymer (A) may be either a carboxyl group-containing polymer or a salt thereof.
• the polymer (A) is a carboxyl group-containing polymer salt, that is, a carboxyl group-containing
• a preferred embodiment is a salt in which at least part of the acid groups of the polymer are neutralized.
• the degree of neutralization of the polymer (A) is from the viewpoint of further improving the cycle characteristics of the lithium ion secondary battery and reducing the internal resistance of the electrode. , preferably 70 mol% or more, more preferably 75 mol% or more, still more preferably 80 mol% or more, even more preferably 85 mol% or more, and 90 mol% or more More preferably.
• the degree of neutralization of the polymer (A) is sufficiently high, and the amount of structural units derived from crosslinkable monomers in the polymer (A) is the total amount of structural units derived from non-crosslinkable monomers. is sufficiently small, the effect of improving the cycle characteristics of the lithium ion secondary battery can be enhanced.
• the preferred ranges of the degree of neutralization of the polymer (A) and the amount of structural units derived from the crosslinkable monomer are the same as above.
• a polymerization method for producing the polymer (A) is not particularly limited.
• the polymer (A) can be obtained by polymerizing monomers by employing known polymerization methods such as solution polymerization, precipitation polymerization, suspension polymerization and emulsion polymerization.
• precipitation polymerization or suspension polymerization is preferred from the viewpoint of productivity.
• Heterogeneous polymerization methods such as precipitation polymerization, suspension polymerization, and emulsion polymerization are preferred from the viewpoint of improving performance such as binding properties, and precipitation polymerization is particularly preferred.
• Precipitation polymerization is a method of producing a polymer by conducting a polymerization reaction in a solvent that dissolves unsaturated monomers but does not substantially dissolve the resulting polymer.
• the polymer particles aggregate and grow as the polymerization progresses, resulting in a dispersion of polymer particles in which primary particles of several tens of nanometers to several hundreds of nanometers are secondary aggregated to several micrometers to several tens of micrometers. It is preferable to use a dispersion stabilizer in order to suppress aggregation of the polymer particles and stabilize them.
• Precipitation polymerization in which secondary aggregation of polymer particles is suppressed by adding a dispersion stabilizer or the like is also called "dispersion polymerization".
• a solvent selected from water and various organic solvents can be used as the polymerization solvent, taking into consideration the type of monomers to be used. From the viewpoint of obtaining a polymer having a long primary chain length, it is preferable to use a solvent with a small chain transfer constant.
• the polymerization solvent examples include water-soluble solvents such as methanol, t-butyl alcohol, acetone, methyl ethyl ketone, acetonitrile and tetrahydrofuran, as well as benzene, ethyl acetate, dichloroethane, n-hexane, cyclohexane and n-heptane. .
• water-soluble solvents such as methanol, t-butyl alcohol, acetone, methyl ethyl ketone, acetonitrile and tetrahydrofuran, as well as benzene, ethyl acetate, dichloroethane, n-hexane, cyclohexane and n-heptane.
• the polymerization solvent one type may be used alone, or two or more types may be used in combination. Among these, the formation of coarse particles and adhesion to the reactor can be suppressed,
• a highly polar solvent it is preferable to add a small amount of a highly polar solvent to the polymerization solvent in order to allow the neutralization reaction to proceed stably and rapidly in the process neutralization.
• Water and methanol can be preferably used as such a highly polar solvent.
• the amount of the highly polar solvent used is preferably 0.05 to 20% by mass, more preferably 0.1 to 10% by mass, based on the total mass of the solvent.
• the monomer concentration at the start of polymerization is usually about 2 to 40% by mass, preferably 5 to 40% by mass, from the viewpoint of obtaining a polymer having a longer primary chain length. .
• the higher the monomer concentration during polymerization the higher the molecular weight of the polymer and the longer the primary chain length of the polymer.
• a basic compound can be preferably used as the dispersion stabilizer.
• the base compound may be either an inorganic base compound or an organic base compound.
• these inorganic base compounds include alkali metal hydroxides such as lithium hydroxide, sodium hydroxide and potassium hydroxide; alkaline earth metal hydroxides such as calcium hydroxide and magnesium hydroxide; be done.
• Organic base compounds include organic amine compounds such as monoethylamine, diethylamine, triethylamine and tri-n-octylamine; ammonia and the like. Of these, organic amine compounds are preferred from the viewpoint of polymerization stability and binding properties of the electrode binder.
• the amount of the basic compound used can be set as appropriate, but it is preferably in the range of 0.001 to 4.0 mol% with respect to the total amount of carboxylic acid monomers used for polymerization.
• the amount of the basic compound used is preferably 0.05 to 4.0 mol%, more preferably 0.1 to 3.0 mol%, relative to the total amount of carboxylic acid monomers used in the polymerization. .
• the amount of the basic compound used represents the molar concentration of the basic compound used with respect to the carboxylic acid monomer, and does not mean the degree of neutralization. That is, the valence of the basic compound used is not considered.
• polymerization initiator known polymerization initiators such as azo compounds, organic peroxides and inorganic peroxides can be used.
• azo compounds include 2,2′-azobis(2,4-dimethylvaleronitrile), 2,2′-azobis(N-butyl-2-methylpropionamide), 2-(tert-butylazo )-2-cyanopropane, 2,2′-azobis(2,4,4-trimethylpentane), 2,2′-azobis(2-methylpropane) and the like.
• the amount of the polymerization initiator to be used is usually 0.001 to 2 parts by mass with respect to 100 parts by mass of the total amount of monomers used for polymerization. From the viewpoint of obtaining, it is preferably 0.005 to 1 part by mass.
• the polymerization temperature is preferably 0 to 100°C, more preferably 20 to 80°C, although it depends on conditions such as the type and concentration of the monomers used.
• the polymerization temperature may be constant or may vary during the polymerization reaction.
• the polymerization time is preferably 1 minute to 20 hours, more preferably 1 hour to 10 hours.
• the polymer dispersion liquid obtained by the above polymerization is subjected to drying treatment such as reduced pressure and/or heat treatment, and the solvent is distilled off, whereby the desired polymer can be obtained in the form of powder.
• drying treatment such as reduced pressure and/or heat treatment
• the solvent is distilled off, whereby the desired polymer can be obtained in the form of powder.
• solid-liquid separation treatment such as centrifugation and filtration
• Solvents used in the washing treatment include water, methanol, and the same solvent as the polymerization solvent.
• an alkaline compound is added to the polymer dispersion obtained by the above polymerization to neutralize the polymer (hereinafter also referred to as “process neutralization”). After that, a drying treatment may be performed to remove the solvent. Further, after obtaining the polymer powder without performing the process neutralization treatment, an alkaline compound is added to neutralize the polymer when preparing the composition for forming the electrode mixture layer (hereinafter referred to as “post-neutralization”). (also referred to as “neutralization”). When the polymer (A) is obtained by precipitation polymerization, in-process neutralization is preferable because secondary aggregates tend to be easily disintegrated.
• a dispersion liquid in which polymer particles are dispersed in the liquid is obtained.
• a method for isolating the polymer particles from the dispersion is not particularly limited, and a known method can be employed.
• the desired polymer particles are recovered by subjecting the dispersion liquid to, for example, distillation of volatile matter (liquid medium, etc.), reprecipitation treatment, vacuum drying, heat drying, filtration, centrifugation, decantation, or the like. can do.
• the composition for forming an electrode mixture layer of the present disclosure is a polymer composition used for forming an electrode (more specifically, an electrode mixture layer) of a lithium ion secondary battery containing a polymer solid electrolyte. , is preferably used as an electrode material for producing a positive electrode (working electrode).
• the composition for forming an electrode mixture layer of the present disclosure (hereinafter, also simply referred to as "this composition") contains the above polymer (A) and an active material.
• the active material blended in the present composition is a positive electrode active material.
• positive electrode active materials include lithium-containing composite phosphates, lithium-containing composite silicates, and lithium salts of transition metal oxides.
• Lithium-containing complex phosphates include lithium-containing complex phosphates having an olivine structure.
• Specific examples of lithium-containing composite phosphates having an olivine structure include salts represented by “LiMPO 4 ” (where M is Fe(II), Mn(II), Co(II) and Ni(II) one or more of).
• LiMPO4 Specific examples of the salt represented by " LiMPO4 " include LiFePO4 , LiNiPO4 , LiCoPO4 , LiMnPO4 , LiFeaNibPO4 , LiFeaCobPO4 , LiFeaMnbPO4 , LiNia CobPO4 , LiNiaMnbPO4 (where a+ b is 1 or less , 0 ⁇ a ⁇ 1, 0 ⁇ b ⁇ 1), LiFecNidCoePO4 , LiFecNidMnePO4 , LiNic Co d Mn e PO 4 (where c + d + e is 1 or less, 0 ⁇ c ⁇ 1, 0 ⁇ d ⁇ 1, 0 ⁇ e ⁇ 1), LiFef Ni g Co h Mni PO 4 (where f + g + h + i is 1 or less , 0 ⁇ f ⁇ 1, 0 ⁇ g ⁇ 1,
• lithium-containing composite silicate examples include Li 2 FeSiO 4 , Li 2 MnSiO 4 , Li 2 CoSiO 4 and the like.
• Lithium salts of transition metal oxides include layered rock salt-type lithium-containing metal oxides and spinel-type lithium-containing metal oxides.
• lithium-containing composite phosphates are preferred, and LiFePO 4 (lithium iron phosphate) is particularly preferred.
• the positive electrode active material one of the above materials may be used alone, or two or more of them may be used in combination as a mixture or composite.
• the polymer (A) is preferably used as a positive electrode binder for binding the positive electrode active material.
• the content of the polymer (A) in the present composition is, for example, 0.1 to 20 parts by mass with respect to 100 parts by mass of the active material contained in the present composition.
• the content of the polymer (A) is 0.1 parts by mass or more, sufficient binding properties and dispersion stability of the active material can be ensured.
• the amount is 20 parts by mass or less, it is possible to suppress the viscosity of the present composition from increasing, and it is preferable in that the coatability to the current collector can be improved.
• the content of the polymer (A) is preferably 0.5 parts by mass or more, more preferably 2 parts by mass or more, and still more preferably 5 parts by mass or more, relative to the total amount of the active material.
• the upper limit of the content of the polymer (A) is preferably 19 parts by mass or less, more preferably 17 parts by mass or less, and even more preferably 15 parts by mass or less with respect to 100 parts by mass of the total amount of the active material.
• the composition may further contain components (hereinafter also referred to as "other components") different from the polymer (A) and the active material.
• Other components include a conductive aid, a medium, and the like.
• the conductive aid is used for the purpose of improving the electrical conductivity of the electrode.
• Conductive aids include carbon-based materials such as carbon black, carbon nanotubes, carbon fibers, graphite fine powder, and carbon fibers. Among these, carbon black, carbon nanotubes and carbon fibers are preferred in that they exhibit excellent conductivity. As carbon black, ketjen black and acetylene black are preferable.
• a conductive support agent you may use individually by 1 type, and may use it in combination of 2 or more type.
• the content of the conductive aid is, for example, 0.2 to 20 parts by mass with respect to 100 parts by mass of the total amount of the active material contained in the present composition, from the viewpoint of achieving both conductivity and energy density. , preferably 0.5 to 17 parts by mass, more preferably 1 to 15 parts by mass.
• the composition is preferably in the form of a slurry containing the polymer (A) and the active material from the viewpoint of improving the coatability onto the current collector.
• Water is preferably used as the medium when the composition is in the form of a slurry.
• the medium may include lower alcohols such as methanol and ethanol; carbonates such as ethylene carbonate; ketones such as acetone; cyclic ethers such as tetrahydrofuran; A mixed solvent of water and a water-soluble organic solvent such as When a mixed solvent is used as the medium, the proportion of water in the mixed solvent is, for example, 50% by mass or more, preferably 70% by mass or more.
• the amount of the medium contained in the composition is, for example, 25-90% by mass, preferably 35-70% by mass, based on the total amount of the composition.
• the present composition may be in a wet powder state capable of forming an electrode mixture layer on the surface of the current collector by pressing.
• the amount of the medium contained in the composition is, for example, 3 to 40% by weight, preferably 10 to 30% by weight, based on the total amount of the composition.
• the present composition may contain components other than the conductive aid and the medium as other components within a range that does not impair the effects of the present disclosure.
• Components other than the conductive aid and medium include, for example, other binder components such as styrene/butadiene latex, acrylic latex and polyvinylidene fluoride latex.
• the composition can be prepared by mixing the polymer (A), the active material, and other ingredients blended as necessary.
• a method for mixing each component is not particularly limited, and a known method can be appropriately adopted. Among them, a method of dry-blending the powder components of the active material, the conductive aid and the polymer (A), and then mixing with a dispersion medium such as water and dispersing and kneading is preferred.
• a dispersion medium such as water and dispersing and kneading
• known mixers such as a planetary mixer, a thin-film swirling mixer, and a rotation-revolution mixer can be used as a mixing device.
• the thin-film whirl type mixer can be preferably used in that a good dispersion state can be obtained in a short period of time.
• the viscosity of the slurry is, for example, 500 to 100,000 mPa s as a value measured by a Brookfield viscometer under conditions of a rotor speed of 60 rpm and 25° C., preferably 1, 000 to 50,000 mPa ⁇ s.
• the present composition when obtained in a wet powder state, it is preferably kneaded to a uniform state without concentration unevenness using a Henschel mixer, a blender, a planetary mixer, a twin-screw kneader, or the like.
• the lithium-ion secondary battery electrode of the present disclosure (hereinafter also referred to as "the present electrode”) includes a current collector and an electrode mixture layer.
• the present electrode is preferably a positive electrode (working electrode) of a lithium ion secondary battery.
• examples of current collectors that is, positive electrode current collectors
• the electrode mixture layer is arranged on the surface of the current collector so as to be adjacent to the current collector, and is formed from the electrode mixture layer-forming composition of the present disclosure.
• the electrode mixture layer is formed, for example, by applying the present slurry composition on the surface of the current collector and then removing the solvent by drying.
• the method of applying the present composition to the surface of the current collector is not particularly limited, and known methods such as doctor blade method, dip method, roll coating method, comma coating method, curtain coating method, gravure coating method and extrusion method. can be adopted.
• the dry removal treatment can be carried out by known methods such as warm air blowing, pressure reduction, (far) infrared rays, and microwave irradiation.
• the electrode mixture layer obtained after drying is usually subjected to compression treatment using a mold press, a roll press, or the like.
• compression treatment By performing the compression treatment, the active material and the electrode binder can be adhered to each other, and the strength of the electrode mixture layer and the adhesion to the current collector can be improved.
• the compression treatment can adjust the thickness of the electrode mixture layer to, for example, about 30 to 80% of the thickness before compression.
• the thickness of the electrode mixture layer after compression is usually about 4 to 200 ⁇ m.
• the lithium ion secondary battery of the present disclosure (hereinafter also referred to as "the present secondary battery”) is a secondary battery containing a polymer solid electrolyte, and includes the lithium ion secondary battery electrode of the present disclosure described above. More specifically, the present secondary battery is an all-solid battery that includes a positive electrode, a negative electrode, and a separator, with a solid polymer electrolyte interposed between the positive electrode and the negative electrode as a separator. In the present secondary battery, it is preferable that the positive electrode of the two electrodes is formed of the electrode mixture layer-forming composition containing the polymer (A).
• the material constituting the negative electrode is not particularly limited, and can be appropriately selected and used from known materials as electrode materials for lithium ion secondary batteries.
• a metal foil such as a copper foil or a lithium foil can be used as the negative electrode current collector.
• the polymer solid electrolyte of the present secondary battery preferably contains an alkylene carbonate group-containing polymer as a polymer component.
• a polymer solid electrolyte containing an alkylene carbonate group-containing polymer is preferable in that both flexibility and high ion conductivity can be achieved. Further, by combining a polymer solid electrolyte containing an alkylene carbonate group-containing polymer and an electrode mixture layer formed from an electrode mixture layer-forming composition containing the polymer (A), good cycle characteristics can be obtained. The lithium ion secondary battery shown can be obtained.
• the alkylene carbonate group-containing polymer is not particularly limited as long as it has an alkylene carbonate group in its main chain.
• a polymer having a structural unit represented by the following general formula (1) can be preferably used.
• -[O-CO-OR 1 ]- (1) (In formula (1), R 1 is a linear or branched alkylene group having 2 to 6 carbon atoms.)
• alkylene carbonate group-containing polymers include polyethylene carbonate, polypropylene carbonate, polyisoprene carbonate, polybutylene carbonate, polypentylene carbonate, and polyhexylene carbonate.
• polyethylene carbonate is particularly preferred.
• the alkylene carbonate group-containing polymer one type can be used alone or two or more types can be used in combination.
• a solid polymer electrolyte contains a lithium salt as an electrolyte salt.
• Lithium salts contained in the solid polymer electrolyte include, for example, LiBr, LiCl, LiI, LiSCN, LiBF 4 , LiAsF 6 , LiClO 4 , CH 3 COOLi, CF 3 COOLi, LiCF 3 SO 3 , LiPF 6 , LiC(CF 3 SO 2 ) 3 , lithium bis(fluorosulfonyl)imide (Li + (FSO 2 ) 2 N ⁇ ), lithium bis(trifluoromethanesulfonyl) imide (Li + (CF 3 SO 2 ) 2 N ⁇ ), and the like. be done.
• the electrolyte salt a salt of the anion of the lithium salt described above and an alkali metal (for example, potassium, sodium, etc.) other than lithium may be used.
• the electrolyte salt contained in the polymer electrolyte is preferably lithium bis(fluorosulfonyl)imide or lithium bis(trifluoromethanesulfonyl)imide.
• the polymer solid electrolyte may contain other components as necessary in addition to the alkylene carbonate group-containing polymer and the electrolyte salt described above.
• Other components that may be contained in the polymer solid electrolyte include, for example, fillers and leveling agents.
• the content of other components in the polymer solid electrolyte can be appropriately selected according to each compound within a range that does not cause deterioration in performance as an electrolyte.
• the method for manufacturing the present secondary battery is not particularly limited, and a known method can be appropriately adopted according to the battery structure and the like.
• a separator-forming composition for example, a composition containing an alkylene carbonate group-containing polymer, an electrolyte salt and a solvent
• a separator-forming composition for example, a composition containing an alkylene carbonate group-containing polymer, an electrolyte salt and a solvent
• the solvent is removed by drying treatment such as heating or reduced pressure to form a separator (solid polymer electrolyte) on one electrode.
• a separator solid polymer electrolyte
• the obtained laminate may be used, for example, as a film type or coin type lithium ion battery, or may be used as a wound type lithium ion battery, or may be used as a laminated lithium ion battery. good too.
• the shape of the secondary battery is not particularly limited, and examples thereof include a button type, a cylindrical type, a square type, a laminate type, and the like.
• the electrode binder of the present disclosure containing the polymer (A) exhibits excellent binding properties to the active material and excellent adhesiveness to the current collector in the electrode mixture layer, while at the same time
• the surface smoothness and internal resistance can be improved, and the initial battery capacity and cycle characteristics of the lithium ion secondary battery can be improved.
• a lithium-ion secondary battery containing an alkylene carbonate group-containing polymer in a polymer solid electrolyte exhibits high ion conductivity even at room temperature. Therefore, the lithium ion secondary battery can have excellent battery performance and high safety. Further, a polymer solid electrolyte containing an alkylene carbonate group-containing polymer has high flexibility, and a flexible secondary battery can also be obtained.
• the polymer (A) has a long primary chain length. It is presumed that this is because the dispersibility of the active material in the electrode can be increased by facilitating the formation of a polymer network in the composition for forming the electrode mixture layer (preferably, an aqueous slurry). .
• the reason why the lithium ion secondary battery obtained by using the electrode binder containing the polymer (A) exhibited good cycle characteristics is that the polymer (A) used as the electrode binder has a primary chain length of is sufficiently long and has a polar functional group, it is easy to interact with the components of the solid polymer electrolyte, which improves the adhesion between the electrode and the solid polymer electrolyte and improves the durability. be done.
• the polymer solid electrolyte contains an alkylene carbonate group-containing polymer, the carbonyl group of the alkylene carbonate group-containing polymer easily interacts with the polar functional group of the polymer (A), which is preferable.
• the lithium ion secondary battery of the present disclosure can be applied to various uses. Specifically, for example, various mobile devices such as mobile phones, personal computers, smartphones, game devices, wearable terminals; various moving bodies such as electric vehicles, hybrid vehicles, robots, and drones; digital cameras, video cameras, music players, electric It can be used as a power source in various electric/electronic devices such as tools and home electric appliances.
• various mobile devices such as mobile phones, personal computers, smartphones, game devices, wearable terminals
• various moving bodies such as electric vehicles, hybrid vehicles, robots, and drones
• digital cameras, video cameras, music players, electric It can be used as a power source in various electric/electronic devices such as tools and home electric appliances.
• Triethylamine was charged in an amount corresponding to 1.0 mol % with respect to AA. After the interior of the reactor was sufficiently replaced with nitrogen, the interior temperature was raised to 55°C by heating. After confirming that the internal temperature has stabilized at 55° C., 2,2′-azobis(2,4-dimethylvaleronitrile) (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., trade name “V-65”) is added as a polymerization initiator. When 0.040 part was added, cloudiness was observed in the reaction solution, and this point was taken as the polymerization initiation point. Incidentally, the monomer concentration was calculated to be 15.0%.
• the polymerization reaction was continued while maintaining the internal temperature at 55°C by adjusting the external temperature (water bath temperature). After 12 hours from the polymerization initiation point, cooling of the reaction solution was started, and after the internal temperature had decreased to 25°C, powder of lithium hydroxide monohydrate (hereinafter referred to as “LiOH.H 2 O”) was added. 52.4 parts were added. After the addition, stirring was continued for 12 hours at room temperature to obtain a slurry-like polymerization reaction liquid in which particles of a carboxyl group-containing crosslinked polymer salt (Li salt, degree of neutralization 90 mol %) were dispersed in a medium.
• the carboxyl group-containing crosslinked polymer salt obtained by the above reaction is referred to as "crosslinked polymer salt R-1".
• AA acrylic acid
• HEA 2-hydroxyethyl acrylate
• T-20 trimethylolpropane diallyl ether (manufactured by Osaka Soda Co., Ltd., trade name "Neoallyl T-20")
• P-30 Pentaerythritol triallyl ether (manufactured by Osaka Soda Co., Ltd., trade name "Neoallyl P-30”)
• TEA triethylamine
• AcN acetonitrile
• V-65 2,2'-azobis (2,4-dimethylvaleronitrile) (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.)
• LiOH.H 2 O Lithium hydroxide monohydrate
• the crosslinked polymer salt R-1 was measured for a 5 mass% aqueous solution viscosity at a rotor speed of 0.6 rpm using an E-type viscometer (manufactured by Toki Sangyo Co., Ltd., TV-20). was s.
• AC-10SHP Polyacrylic acid powder
• Polyacrylic acid powder manufactured by Toagosei Co., Ltd., trade name "Jurimer AC-10SHP", hereinafter also referred to as "AC-10SHP"
• AC-10SHP Polyacrylic acid powder
• Lithium hydroxide.monohydrate LiOH.H 2 O
• LiOH.H 2 O Lithium hydroxide.monohydrate
• PAA Polyacrylic acid powder
• Polyacrylic acid powder manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., trade name “Polyacrylic acid 250,000", hereinafter also referred to as "PAA"
• PAA Polyacrylic acid 250,000
• Lithium hydroxide.monohydrate LiOH.H 2 O
• Example 1 Production and Evaluation of Lithium Ion Secondary Battery
• electrode plate for working electrode 80 parts of lithium iron phosphate (manufactured by Tatung Fine Chemicals, trade name “Lithium iron phosphate”) as an active material and acetylene black (manufactured by Denka Corporation) as a conductive agent , trade name “Denka Black”), 10 parts of crosslinked polymer salt R-1 as a binder for electrodes, and 400 parts of water as a medium are mixed with Awatori Rentaro (2,000 rpm, 20 minutes), A composition for forming an electrode mixture layer was prepared.
• lithium iron phosphate manufactured by Tatung Fine Chemicals, trade name “Lithium iron phosphate”
• acetylene black manufactured by Denka Corporation
• a working electrode mixture layer was formed as an electrode mixture layer by coating and drying this composition for forming an electrode mixture layer on an aluminum current collector (thickness: 20 ⁇ m). After that, it was rolled so that the working electrode mixture layer had a thickness of 55 ⁇ m and a mixture density of 0.7 g/cm 3 , and was punched into a disk shape with a diameter of 1.4 cm to obtain a working electrode plate.
• Negative Electrode Plate A negative electrode plate was obtained by punching a 20 ⁇ m-thick metallic lithium foil (manufactured by Honjo Metal Co., Ltd.) into a disk shape with a diameter of 1.5 cm.
• the resulting coin-type battery was subjected to AC impedance measurement (applied voltage: 30 mV) using a potentiostat/galvanostat (manufactured by BioLogic SP-300) at a frequency range of 1 MHz to 0.1 Hz to obtain a Nyquist plot. rice field.
• AC impedance measurement is a method of applying AC to measure a resistance component.
• the obtained Nyquist plot was subjected to fitting calculation using an equivalent circuit to calculate the value of the working electrode resistance, which was 324 ⁇ .
• Electrode surface smoothness The surface of the working electrode was observed with a scanning electron microscope (SEM, device name: JCM600 Plus manufactured by JEOL Ltd.) and evaluated according to the following criteria. . (Evaluation criteria) ⁇ : No appearance abnormality such as unevenness is observed on the surface. ⁇ : Small unevenness is slightly recognized on the surface. x: Appearance abnormalities such as large irregularities and cracks are remarkably observed on the surface.
• Examples 2 to 6 and Comparative Example 1 A button type battery was produced in the same manner as in Example 1, except that the amount of each compound was charged as shown in Table 2. In addition, battery evaluation was performed in the same manner as in Example 1 for each of the manufactured button-type batteries. Table 2 shows the results.
• Example 2 A button type battery was produced in the same manner as in Example 1, except that the amount of each compound was charged as shown in Table 2. Instead of water, N-methyl-2-pyrrolidone (NMP) in which the electrode binder dissolves was used as the medium for the electrode mixture layer-forming composition. In addition, battery evaluation was performed in the same manner as in Example 1 for the manufactured button type battery. Table 2 shows the results.
• NMP N-methyl-2-pyrrolidone
• AC-10SHP Polyacrylic acid powder (manufactured by Toagosei Co., Ltd., trade name “Jurimer AC-10SHP”)
• PAA polyacrylic acid powder (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., trade name “polyacrylic acid 250,000”)
• PVDF Polyvinylidene fluoride (manufactured by Solvay, trade name “Solef5130”)
• LFP lithium iron phosphate (manufactured by Tatung Fine Chemicals, trade name “Lithium iron phosphate”)
• AB Acetylene black (manufactured by Denka, trade name “Denka Black”)
• NMP N-methyl-2-pyrrolidone
• Examples 1 to 6 are examples using an aqueous binder containing a carboxyl group-containing polymer salt having a 5 mass% aqueous solution viscosity of 1,960 mPa s at 25 ° C.
• an organic solvent binder As compared with the example using PVDF (Comparative Example 2), the electrode surface smoothness was excellent, the internal resistance of the electrode was small, the initial battery capacity was high, and the cycle characteristics were excellent.
• Examples 1 to 6 examples (Examples 1, 3, and 4) using a slightly crosslinked type electrode binder having a sufficiently high degree of lithium neutralization and a small amount of crosslinkable monomer used are good. cycle characteristics. This is probably because the slightly crosslinked type electrode binder tends to form a wide polymer network in water.

Landscapes

• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• General Chemical & Material Sciences (AREA)
• Electrochemistry (AREA)
• Engineering & Computer Science (AREA)
• Inorganic Chemistry (AREA)
• Materials Engineering (AREA)
• Manufacturing & Machinery (AREA)
• Health & Medical Sciences (AREA)
• Medicinal Chemistry (AREA)
• Polymers & Plastics (AREA)
• Organic Chemistry (AREA)
• Crystallography & Structural Chemistry (AREA)
• Physics & Mathematics (AREA)
• Condensed Matter Physics & Semiconductors (AREA)
• Dispersion Chemistry (AREA)
• General Physics & Mathematics (AREA)
• Battery Electrode And Active Subsutance (AREA)

Priority Applications (4)

Applications Claiming Priority (2)

Publications (1)

Family

ID=85155562

Family Applications (1)

Country Status (5)

Families Citing this family (1)

Citations (5)

Family Cites Families (3)

• 2022
  • 2022-08-01 WO PCT/JP2022/029517 patent/WO2023013594A1/ja not_active Ceased
  • 2022-08-01 KR KR1020247001069A patent/KR20240042405A/ko active Pending
  • 2022-08-01 US US18/681,700 patent/US20250140861A1/en active Pending
  • 2022-08-01 CN CN202280048628.1A patent/CN117616601A/zh active Pending
  • 2022-08-01 JP JP2023540337A patent/JPWO2023013594A1/ja active Pending

Patent Citations (5)

Also Published As

Similar Documents

Legal Events