WO2022210738A1 - Composition pour électrode négative, feuille d'électrode négative, batterie secondaire non aqueuse, et procédé de fabrication de feuille d'électrode négative et de batterie secondaire non aqueuse - Google Patents

Composition pour électrode négative, feuille d'électrode négative, batterie secondaire non aqueuse, et procédé de fabrication de feuille d'électrode négative et de batterie secondaire non aqueuse Download PDF

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WO2022210738A1
WO2022210738A1 PCT/JP2022/015556 JP2022015556W WO2022210738A1 WO 2022210738 A1 WO2022210738 A1 WO 2022210738A1 JP 2022015556 W JP2022015556 W JP 2022015556W WO 2022210738 A1 WO2022210738 A1 WO 2022210738A1
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negative electrode
water
soluble polymer
secondary battery
mass
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Japanese (ja)
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祥平 片岡
郁雄 木下
景 河野
一樹 瀧本
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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 WO2022210738A1 publication Critical patent/WO2022210738A1/fr

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    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K3/00—Use of inorganic substances as compounding ingredients
    • C08K3/34—Silicon-containing compounds
    • C08K3/36—Silica
    • 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
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L33/00—Compositions of homopolymers or 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 of salts, anhydrides, esters, amides, imides or nitriles thereof; Compositions of derivatives of such polymers
    • C08L33/04—Homopolymers or copolymers of esters
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L33/00—Compositions of homopolymers or 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 of salts, anhydrides, esters, amides, imides or nitriles thereof; Compositions of derivatives of such polymers
    • C08L33/24—Homopolymers or copolymers of amides or imides
    • C08L33/26—Homopolymers or copolymers of acrylamide or methacrylamide
    • 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
    • H01M4/139—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
    • H01M4/36—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
    • H01M4/48—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

Definitions

  • the present invention relates to a negative electrode composition, a negative electrode sheet, a non-aqueous secondary battery, a method for manufacturing a negative electrode sheet, and a method for manufacturing a non-aqueous secondary battery.
  • Secondary batteries typified by lithium-ion secondary batteries, are used as power sources for portable electronic devices such as personal computers, video cameras, and mobile phones. Recently, against the background of the global environmental issue of reducing carbon dioxide emissions, it is becoming popular as a power source for transportation equipment such as automobiles, and as a power storage application such as nighttime power and power generated by natural energy generation.
  • the electrodes (positive electrode and negative electrode) of the lithium ion secondary battery have an electrode active material layer (positive electrode active material layer and negative electrode active material layer), and this electrode active material layer can absorb or release lithium ions during charging and discharging.
  • electrons are also transported between the electrode active material particles or between the electrode active material particles and the current collector, it is required to ensure electron conductivity.
  • the binding between the electrode active material particles or between the electrode active material particles and the current collector is important for the efficiency of this electron conduction, and the electrode active material layer usually contains a binder.
  • silicon oxide As a negative electrode active material, studies on using silicon oxide as a negative electrode active material have been actively conducted.
  • the theoretical capacity of silicon oxide is remarkably higher than that of graphite, etc., making it possible to increase the energy density of batteries.
  • silicon oxide When silicon oxide is used as the negative electrode active material, it absorbs a large amount of lithium ions and expands greatly during charging, and the shrinkage width of silicon oxide during discharging is correspondingly increased. Therefore, in a lithium-ion battery using silicon oxide as a negative electrode active material, the volume of the negative electrode active material changes greatly during charging and discharging, and the battery performance tends to deteriorate due to repeated charging and discharging. In other words, there are restrictions on improving the cycle life.
  • Patent Document 1 discloses a negative electrode active material containing 20% by mass or more of silicon particles having a median diameter of 0.1 to 2 ⁇ m, a (meth)acrylamide skeleton-containing monomer and sulfonic acid.
  • a lithium ion battery negative electrode comprising poly(meth)acrylamide, which is a radical copolymer of a monomer group containing a group-substituted unsaturated hydrocarbon group-containing monomer and exhibits a specific high viscosity in an aqueous solution of a specific concentration, and water A slurry is described. According to the technique described in Patent Document 1, it is said that a lithium ion secondary battery having excellent cycle life (cycle characteristics) can be obtained using this negative electrode slurry.
  • Electrodes for lithium-ion secondary batteries are usually formed by applying an electrode-forming composition (slurry) onto a current collector and drying it. Therefore, a slurry for electrode formation is prepared by dispersing an electrode active material and a binder in a liquid medium.
  • a slurry for electrode formation is prepared by dispersing an electrode active material and a binder in a liquid medium.
  • the present invention relates to a negative electrode composition using carbon-coated silicon oxide as a negative electrode active material, which is used to form a negative electrode active material layer of a nonaqueous secondary battery.
  • An object of the present invention is to provide a negative electrode composition capable of sufficiently extending the cycle life while achieving high capacity and low resistance.
  • a further object of the present invention is to provide a negative electrode sheet and a non-aqueous secondary battery using the negative electrode composition.
  • a further object of the present invention is to provide a method for manufacturing the negative electrode sheet and the non-aqueous secondary battery.
  • the present inventors have extensively studied a binder to be combined with carbon-coated silicon oxide from the viewpoint of the polymer structure that constitutes the binder.
  • the weight-average molecular weight is suppressed to 300,000 or less, and the interaction with the active material or the interaction between polymers is expected.
  • the above technical problems can be solved at a high level by including a specific amount or more of a water-soluble polymer in the binder in which the content of the component having an acid group is suppressed to 5% by mass or less. rice field.
  • the present invention has been completed through further studies based on these findings.
  • the binder contains 5% by mass or more of a water-soluble polymer
  • the composition for a negative electrode wherein the water-soluble polymer has a weight average molecular weight of 300,000 or less, and the component having an acid group accounts for 5% by mass or less of the water-soluble polymer.
  • R 1 represents a hydrogen atom or a methyl group
  • L 1 represents a single bond or a linking group
  • R 2 represents a substituent. * indicates a binding site for incorporation into the water-soluble polymer.
  • R3 represents a hydrogen atom or a methyl group
  • R4 and R5 represent a hydrogen atom or a substituent. * indicates a binding site for incorporation into the water-soluble polymer.
  • ⁇ 4> The negative electrode composition according to any one of ⁇ 1> to ⁇ 3>, wherein the content of the water-soluble polymer is 2 parts by mass or more with respect to 100 parts by mass of the carbon-coated silicon oxide. .
  • ⁇ 5> The negative electrode composition according to ⁇ 3>, wherein the water-soluble polymer contains two or more constituents represented by the general formula (1) or (2).
  • ⁇ 6> The negative electrode composition according to any one of ⁇ 1> to ⁇ 5>, wherein the acid group is a carboxy group or a salt thereof.
  • ⁇ 7> The negative electrode composition according to any one of ⁇ 1> to ⁇ 6>, which is a negative electrode slurry containing a dispersion medium.
  • ⁇ 9> It has a positive electrode active material layer, a separator, and a negative electrode active material layer in this order, and the negative electrode active material layer is a layer composed of the negative electrode composition according to any one of ⁇ 1> to ⁇ 7>.
  • non-aqueous secondary battery A method for producing a negative electrode sheet, comprising forming a film using the negative electrode composition according to any one of ⁇ 1> to ⁇ 7>.
  • ⁇ 11> A method for producing a non-aqueous secondary battery, comprising incorporating the negative electrode sheet obtained by the production method according to ⁇ 10> into a negative electrode of the non-aqueous secondary battery.
  • water-soluble polymer means a polymer that dissolves in 1 L of water at 25° C. in an amount of 7 g or more (a polymer whose solubility at 25° C. is 7 [g/1 L-H 2 O] or more).
  • a numerical range represented by "to” means a range including the numerical values before and after "to” as lower and upper limits.
  • the expression of a compound is used to mean the compound itself, its salts, and its ions. It also includes derivatives in which a part of the structure is changed, such as by introducing a substituent, to the extent that the desired effect is achieved.
  • substituents when a substituent has a dissociable hydrogen atom (a group in which a hydrogen atom is dissociated by the action of a base), this substituent includes ions or salts.
  • the carboxy group when a compound has a carboxy group, the carboxy group may exist as an anion by dissociating a hydrogen atom, and the anion may form a salt with a counterion (cation).
  • Counterions are not particularly limited, and examples thereof include alkali metal ions such as lithium ions, sodium ions and potassium ions.
  • substituents, linking groups, etc. hereinafter referred to as substituents, etc. for which substitution or unsubstitution is not specified are intended to mean that the group may have an appropriate substituent.
  • non-aqueous secondary battery is meant to include non-aqueous electrolyte secondary batteries and all-solid secondary batteries.
  • non-aqueous electrolyte means an electrolyte that does not substantially contain water.
  • the "non-aqueous electrolyte” may contain a small amount of water as long as the effects of the present invention are not impaired.
  • the "non-aqueous electrolyte” has a water concentration of 200 ppm (by mass) or less, preferably 100 ppm or less, more preferably 20 ppm or less. It is practically difficult to make the non-aqueous electrolyte completely anhydrous, and usually contains 1 ppm or more of water.
  • the "solid content” used when describing the content or content ratio means components other than the dispersion medium described below.
  • the negative electrode composition and the negative electrode sheet of the present invention provide excellent cycle characteristics to a non-aqueous secondary battery using carbon-coated silicon oxide as a negative electrode active material by forming a negative electrode active material layer using them. can do. Therefore, the non-aqueous secondary battery of the present invention has high capacity, low resistance, and excellent cycle characteristics. According to the method for producing a negative electrode sheet of the present invention, the negative electrode sheet of the present invention can be obtained. Moreover, according to the manufacturing method of the non-aqueous secondary battery of the present invention, the non-aqueous secondary battery of the present invention can be obtained.
  • FIG. 1 is a vertical cross-sectional view schematically showing the basic lamination structure of a non-aqueous electrolyte secondary battery.
  • the negative electrode composition of the present invention contains a binder containing a water-soluble polymer and a negative electrode active material containing carbon-coated silicon oxide.
  • the water-soluble polymer has a weight-average molecular weight of 300,000 or less, and the content of the component having an acid group in the water-soluble polymer is 5% by mass or less. This water-soluble polymer is contained in the binder in an amount of 5% by mass or more.
  • the binder contains a certain amount or more of a polymer that has a relatively small weight average molecular weight of 300,000 or less, and the amount of acid groups is limited to suppress the increase in apparent molecular weight. Therefore, it is presumed that one of the reasons for this is that the water-soluble polymer is firmly attached to the negative electrode active material (carbon-coated silicon oxide) by, for example, fitting into the voids of the carbon coating layer (causing an anchor effect). be done.
  • the negative electrode composition of the present invention can be prepared by mixing a binder containing a water-soluble polymer, a negative electrode active material containing carbon-coated silicon oxide, and, if necessary, a dispersion medium, a conductive aid, and the like. .
  • the binder used in the present invention contains 5% by mass or more of the water-soluble polymer described above based on the total amount of the binder.
  • the water-soluble polymer used in the present invention may be either a chain polymerized polymer or a stepwise polymerized polymer, preferably a chain polymerized polymer. There are no particular restrictions on the bond form of the chain polymer, and it may be random or block.
  • the water-soluble polymer preferably contains, for example, a component represented by the following general formula (1) or (2) as a component having no acid group.
  • R 1 represents a hydrogen atom or a methyl group
  • L 1 represents a single bond or a linking group (divalent)
  • R 2 represents a substituent. * indicates a binding site for incorporation into a water-soluble polymer.
  • R3 represents a hydrogen atom or a methyl group
  • R4 and R5 represent a hydrogen atom or a substituent. * indicates a binding site for incorporation into a water-soluble polymer.
  • the linking group that can be used as L1 is not particularly limited as long as it does not have an acid group.
  • the chemical formula weight of this linking group is preferably 14-1000, more preferably 14-500, even more preferably 26-250.
  • Linking groups that can be used as L 1 include, for example, alkylene groups, —O—, carbonyl groups, imino groups, and combinations thereof. As a combination of these, a connecting group formed by combining 2 to 6 groups selected from an alkylene group, —O—, a carbonyl group and an imino group is preferable, and a connecting group formed by combining 2 or 3 groups is more preferable.
  • the alkylene group that can be used as L 1 may be either linear or branched, and the number of carbon atoms in the alkylene group is preferably 1 to 10, more preferably 1 to 8, still more preferably 1 to 6, and can be 1 to 4. Most preferably, it is a methylene group, an ethylene group, an ethylethylene group or a propylene group.
  • the chemical formula weight of L 1 is preferably 14-200, more preferably 14-150, even more preferably 14-80.
  • R 2 is not particularly limited as long as it is a substituent having no acid group.
  • the chemical formula weight of R 2 is preferably 15-200, more preferably 15-150, even more preferably 15-100.
  • R 2 include a hydroxy group, an alkyloxy group, an alkyl group, an amide group and a sulfonamide group, preferably a hydroxy group or an alkyloxy group.
  • the alkyl group in the alkyloxy group may be linear, branched or cyclic.
  • the number of carbon atoms in the alkyl group is preferably 1 to 10, more preferably 1 to 8, still more preferably 1 to 6, particularly preferably 1 to 4, and is any one of a methyl group, an ethyl group and an isopropyl group. is most preferred.
  • the alkyl group has the same definition as the alkyl group in the above alkyloxy group, and the preferred range is also the same.
  • Substituents that can be used as R 4 and R 5 are not particularly limited as long as they are substituents that do not have an acid group.
  • the chemical formula weight of each of R 4 and R 5 is preferably 15-200, more preferably 15-150, even more preferably 15-60.
  • Alkyl groups are preferred as substituents that can be taken as R 4 and R 5 .
  • the alkyl group has the same definition as the alkyl group in the alkyloxy group that can be used as R 2 above, and the preferred range is also the same. It is also preferred that the alkyl groups that can be used as R 4 and R 5 further have substituents.
  • substituents include hydroxy groups, alkylcarbonyl groups, amide groups, and urethane bond-containing groups (--NH--CO--O--R b (R b represents an alkyl group).
  • a hydroxy group is preferable as a substituent of the alkyl group that can be used as R 4 and R 5 .
  • the alkyl group in the alkylcarbonyl group has the same meaning as the alkyl group in the alkyloxy group that can be used as R 2 above, and the preferred range is also the same.
  • the alkyl group represented by R b has the same definition as the alkyl group in the alkyloxy group that can be used as R 2 above, and the preferred range is also the same.
  • Both R 4 and R 5 are preferably a hydrogen atom, or one is a hydrogen atom and the other is a hydroxyalkyl group.
  • the water-soluble polymer used in the present invention may contain one type of component having no acid group alone, or may contain two or more types in combination.
  • the ratio of the component represented by the general formula (1) or (2) in the water-soluble polymer (the ratio of the component represented by the general formula (1) in the water-soluble polymer and the above The total ratio of the constituent components represented by the general formula (2)) is preferably 30% by mass or more, more preferably 50% by mass or more, still more preferably 70% by mass or more, and particularly 90% by mass or more. Preferably, it is most preferably 95% by mass or more. From the viewpoint of improving the cycle characteristics of the secondary battery, the water-soluble polymer used in the present invention preferably contains two or more constituents represented by general formula (1) or (2).
  • constituents are not particularly limited. Examples include components derived from vinyl monomers such as styrene, maleimide, N-vinylacetamide, vinyl esters and vinyl ethers.
  • the "acid group" of the component having an acid group that the water-soluble polymer may have means a group having a dissociative proton or a salt thereof.
  • Salt forms include, for example, alkali metal salts (eg, lithium salts, sodium salts, potassium salts, etc.).
  • the component having the acid group is not particularly limited, and the component usually contains 1 to 3 acid groups, preferably 1 or 2 groups, and more preferably 1 group.
  • the water-soluble polymer contains a component having an acid group, it preferably contains, for example, a component represented by the following general formula (3).
  • R6 represents a hydrogen atom or an acid group.
  • R7 represents a hydrogen atom or a methyl group, L2 represents a single bond or a linking group ( divalent ), and R8 represents an acid group. * indicates a binding site for incorporation into a water-soluble polymer.
  • the linking group that can be used as L 2 is not particularly limited, and examples thereof include an alkylene group, an arylene group, a carbonyl group, an ether bond (--O--), an imino group, or a linking group in which two or more of these are combined.
  • the alkylene group that can be used as L 2 may be either linear or branched, and the number of carbon atoms in the alkylene group is preferably 1 to 10, more preferably 1 to 8, still more preferably 1 to 6, and can be 1 to 4. Particularly preferred are methylene, ethylene, propylene and dimethylethylene groups.
  • the number of carbon atoms in the arylene group that can be taken as L 2 is preferably 6-30, more preferably 6-20, still more preferably 6-15, and particularly preferably 6-10.
  • Specific examples of arylene groups include phenylene groups and naphthylene groups.
  • linking group combining two or more types is a linking group combining at least two types of an alkylene group, an arylene group, a carbonyl group, an ether bond (-O-) and an imino group, and a combination of 2 to 10 types. is preferable, a linking group in which 2 to 7 types are combined is more preferable, and a linking group in which 2 to 4 types are combined is even more preferable.
  • Specific examples of the above-mentioned "linking group combining two or more types” include, for example, "carbonyl group-imino group-alkylene group” and "carbonyl group-ether bond-alkylene group”.
  • the proportion of the component having an acid group in the water-soluble polymer is 5% by mass or less, preferably 4% by mass or less, more preferably 3% by mass or less, further preferably 2% by mass or less, and 1% by mass or less. is particularly preferred, and it is most preferred that the water-soluble polymer does not have constituents with acid groups.
  • the weight average molecular weight of the water-soluble polymer used in the present invention is 300,000 or less, preferably 290,000 or less, more preferably 280,000 or less, and even more preferably 270,000 or less.
  • the weight average molecular weight of the water-soluble polymer is preferably 10,000 or more, more preferably 40,000 or more, still more preferably 100,000 or more, particularly preferably 140,000 or more, and most preferably 170,000 or more.
  • the weight average molecular weight of a polymer is a value obtained by measuring by the method described in the Examples section below.
  • the content of the water-soluble polymer in the binder used in the present invention is 5% by mass or more, preferably 10% by mass or more, more preferably 20% by mass or more, from the viewpoint of improving the cycle characteristics of the secondary battery.
  • the binder used in the present invention may consist of the above water-soluble polymer.
  • the content of the water-soluble polymer in the negative electrode composition is preferably 2 parts by mass or more, and 4 parts by mass with respect to 100 parts by mass of carbon-coated silicon oxide. Part or more is more preferable, and 8 parts by mass or more is even more preferable.
  • the content of the water-soluble polymer in the negative electrode composition is preferably 30 parts by mass or less, more preferably 25 parts by mass or less, and 20 parts by mass or less with respect to 100 parts by mass of carbon-coated silicon oxide. More preferred.
  • the binder used in the present invention can contain polymers other than the above water-soluble polymers.
  • Such polymers include, for example, water-insoluble polymers, water-soluble polymers having a weight-average molecular weight exceeding 300,000, and water-soluble polymers containing constituents having acid groups exceeding 5% by weight. Specific examples of such polymers include polymer B described in Table 1 below, but polymer B is not limited to "polymer B described in Table 1 below".
  • the negative electrode active material used in the present invention includes carbon-coated silicon oxide (SiOx (0 ⁇ x ⁇ 1.5)). Carbon-coated silicon oxide can reversibly store and release lithium ions.
  • the silicon oxide may be coated with carbon over the entire surface, or may have a portion not coated with carbon. Even if the entire surface of silicon oxide is carbon-coated, the carbon-coated layer itself has a large number of voids.
  • the proportion of carbon atoms in the carbon-coated silicon oxide (the total of the carbon coating layer and silicon oxide) is not particularly limited, and is preferably 0.5 to 5% by mass, more preferably 1 to 3% by mass.
  • Carbon-coated silicon oxide may be a commercially available product. For example, referring to JP-A-2019-204686, silicon oxide can be prepared by carbon-coating.
  • the negative electrode active material used in the present invention may contain a negative electrode active material other than carbon-coated silicon oxide.
  • negative electrode active materials other than carbon-coated silicon oxide are referred to as "other negative electrode active materials.”
  • Other negative electrode active materials are preferably those capable of reversibly intercalating and deintercalating lithium ions.
  • the material is not particularly limited as long as it has the above properties, and examples thereof include carbonaceous materials, metal oxides, metal composite oxides, lithium alloys, negative electrode active materials capable of forming an alloy with lithium, and the like.
  • the lithium alloy is not particularly limited as long as it is an alloy normally used as a negative electrode active material for secondary batteries, and examples thereof include lithium aluminum alloys.
  • 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 for secondary batteries.
  • active materials include negative electrode active materials having tin atoms and metals such as Al and In.
  • negative electrode active materials containing tin atoms include Sn, SnO, SnO 2 , SnS, SnS 2 , active materials containing silicon atoms and tin atoms, and the like.
  • composite oxides with lithium oxide such as Li 2 SnO 2 .
  • carbonaceous materials are preferably used as other negative electrode active materials from the viewpoint of reliability.
  • carbonaceous materials used as negative electrode active materials are materials that are substantially made of carbon.
  • carbon black such as petroleum pitch, graphite (natural graphite, artificial graphite such as vapor growth graphite, etc.), and carbonaceous materials obtained by baking various synthetic resins such as PAN (polyacrylonitrile) resin or furfuryl alcohol resin Materials can be mentioned.
  • various carbon fibers such as PAN-based carbon fiber, cellulose-based carbon fiber, pitch-based carbon fiber, vapor growth carbon fiber, dehydrated PVA (polyvinyl alcohol)-based carbon fiber, lignin carbon fiber, vitreous carbon fiber and activated carbon fiber. , mesophase microspheres, graphite whiskers and tabular graphite.
  • metal oxides and metal composite oxides applied as negative electrode active materials are not particularly limited as long as they are oxides capable of intercalating and deintercalating lithium.
  • Chalcogenite which is a reaction product with an element belonging to Group 16 of the Norms Table, is also preferred.
  • amorphous as used herein means a broad scattering band having an apex in the region of 20° to 40° in terms of 2 ⁇ value in an X-ray diffraction method using CuK ⁇ rays, and a crystalline diffraction line.
  • amorphous oxides of metalloid elements and the above chalcogenides are more preferable, elements of groups 13 (IIIB) to 15 (VB) of the periodic table, Particularly preferred are oxides of Al, Ga, Si, Sn, Ge, Pb, Sb and Bi, or a combination of two or more thereof (excluding oxides containing Si), or chalcogenides.
  • Specific examples of preferred amorphous oxides and chalcogenides include Ga 2 O 3 , GeO, PbO, PbO 2 , Pb 2 O 3 , Pb 2 O 4 , Pb 3 O 4 , Sb 2 O 3 and Sb 2 .
  • the metal (composite) oxide and the chalcogenide preferably contain at least one of titanium and lithium as a constituent component from the viewpoint of high current density charge/discharge characteristics.
  • lithium-containing metal composite oxides include composite oxides of lithium oxide and the above metal (composite) oxides or chalcogenides, more specifically Li 2 SnO 2 . mentioned.
  • Other negative electrode active materials preferably contain titanium atoms. More specifically, TiNb 2 O 7 (niobium titanate [NTO]) and Li 4 Ti 5 O 12 (lithium titanate [LTO]) have small volume fluctuations when absorbing and desorbing lithium ions, and are therefore suitable for rapid charging. It is preferable in that it has excellent discharge characteristics, suppresses deterioration of the electrode, and can improve the life of the lithium ion secondary battery.
  • NTO niobium titanate
  • Li 4 Ti 5 O 12 lithium titanate [LTO]
  • the shape of the carbon-coated silicon oxide and other negative electrode active materials is not particularly limited, but is preferably particulate.
  • the volume-based median diameter D50 of carbon-coated silicon oxide and other negative electrode active materials is preferably 0.1 to 60 ⁇ m.
  • a conventional pulverizer or classifier is used to obtain a predetermined particle size.
  • a mortar, a ball mill, a sand mill, a vibrating ball mill, a satellite ball mill, a planetary ball mill, a whirling jet mill, a sieve, or the like is preferably used.
  • wet pulverization can also be performed in which water or an organic solvent such as methanol is allowed to coexist.
  • Classification is preferably carried out in order to obtain a desired particle size.
  • the classification method is not particularly limited, and a sieve, an air classifier, or the like can be used as desired. Both dry and wet classification can be used.
  • the median diameter D50 of carbon-coated silicon oxide is also preferably 0.1 to 30 ⁇ m, more preferably 0.5 to 20 ⁇ m, and particularly preferably 2 to 8 ⁇ m.
  • the median diameter D50 can be determined by a laser diffraction method, for example, using SALD-2300 (trade name) manufactured by Shimadzu Corporation.
  • the mass ratio (carbon-coated silicon oxide/graphite) is preferably 0.1 or more, more preferably 0.2 or more, and even more preferably 0.3 or more.
  • the upper limit of the mass ratio of carbon-coated silicon oxide to graphite is not particularly limited, 4 or less is practical.
  • the content of 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, more preferably 15 to 40% by mass.
  • the mass (mg) (basis weight) of carbon-coated silicon oxide and other negative electrode active materials per unit area (cm 2 ) of the negative electrode active material layer is not particularly limited. do not have. It can be determined appropriately according to the designed battery capacity.
  • the content of carbon-coated silicon oxide and other negative electrode active materials in the negative electrode composition is not particularly limited. 15 to 95% by mass is more preferable.
  • the negative electrode composition of the present invention can also contain a dispersion medium to form a negative electrode slurry.
  • an aqueous medium containing water can be used as the dispersion medium.
  • the "aqueous medium containing water” is water or a mixture of water and a water-soluble organic solvent.
  • water-soluble organic solvent refers to an organic solvent that mixes with water without causing phase separation, and includes, for example, N-methylpyrrolidone, methanol, ethanol, acetone, tetrahydrofuran, and the like.
  • the negative electrode composition of the present invention can also contain a conductive aid.
  • a conductive aid there are no particular restrictions on the conductive aid, and any commonly known conductive aid can be used.
  • graphites such as natural graphite and artificial graphite, carbon blacks such as acetylene black, ketjen black, and furnace black, amorphous carbon such as needle coke, vapor-grown carbon fiber, or carbon nanotube, which are electronic conductive materials
  • Carbon fibers such as carbon fibers such as graphene or fullerene may be used, metal powders such as copper and nickel, metal fibers may be used, and conductive polymers such as polyaniline, polypyrrole, polythiophene, polyacetylene, and polyphenylene derivatives may be used.
  • a negative electrode active material and a conductive aid when used in combination, among the above conductive aids, Li insertion and release do not occur when the secondary battery is charged and discharged, and do not function as a negative electrode active material. is used as a conductive aid. Therefore, among conductive aids, those that can function as a negative electrode active material in a negative electrode active material layer during charging and discharging of a secondary battery are classified as negative electrode active materials instead of conductive aids. Whether or not it functions as a negative electrode active material when a secondary battery is charged and discharged is not univocally determined by the combination with the negative electrode active material.
  • the content of the conductive aid in the negative electrode composition is preferably 10 to 90% by mass, more preferably 30 to 80% by mass, and even more preferably 50 to 70% by mass based on 100% by mass of solid content.
  • the shape of the conductive aid is not particularly limited, but it is preferably particulate.
  • the median diameter D50 of the conductive aid is not particularly limited, and is preferably 0.01 to 50 ⁇ m, preferably 0.02 to 10.0 ⁇ m, for example.
  • the negative electrode composition of the present invention may optionally contain, as components other than the components described above, a lithium salt, an ionic liquid, a thickener, an antifoaming agent, a leveling agent, a dehydrating agent, an antioxidant, and the like. can be done.
  • a cross-linking agent for chemically cross-linking the water-soluble polymer such as one that undergoes a cross-linking reaction by radical polymerization, condensation polymerization, or ring-opening polymerization
  • a polymerization initiator that generates acid or radicals by heat or light
  • the negative electrode sheet of the present invention has a layer (negative electrode active material layer) configured (formed) using the negative electrode composition of the present invention.
  • the negative electrode sheet of the present invention only needs to have a negative electrode active material layer. It may be a sheet formed of This negative electrode sheet is usually a sheet having a structure in which a negative electrode active material layer is laminated on a current collector.
  • the negative electrode sheet of the present invention may have other layers such as a protective layer (release sheet) and a coat layer.
  • the negative electrode sheet of the present invention can be suitably used as a material constituting a negative electrode active material layer of a secondary battery.
  • the negative electrode sheet of the present invention can be obtained by forming a negative electrode active material layer using the negative electrode composition of the present invention.
  • a current collector or the like is used as a base material, and the composition for a negative electrode of the present invention is applied thereon (may be via another layer) to form a coating film, which is dried to form a base material.
  • An electrode sheet having a negative electrode active material layer (coated dry layer) thereon can be obtained.
  • Non-aqueous secondary battery of the present invention means all devices in which ions pass between the positive and negative electrodes through an electrolyte due to charging and discharging, and energy is stored and released at the positive and negative electrodes. That is, the term "non-aqueous secondary battery” as used in the present invention includes both batteries and capacitors (for example, lithium ion capacitors). From the viewpoint of energy storage capacity, the non-aqueous secondary battery of the present invention is preferably used for battery applications (not a capacitor).
  • the non-aqueous secondary battery of the present invention will be described by taking the form of a non-aqueous electrolyte secondary battery as an example, but the secondary battery of the present invention is not limited to the non-aqueous electrolyte secondary battery. It broadly includes all non-aqueous secondary batteries including solid secondary batteries.
  • a non-aqueous electrolyte secondary battery which is a preferred embodiment of the present invention, has a configuration including a positive electrode, a negative electrode, and a separator interposed 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.
  • the negative electrode active material layer is formed using the electrode composition of the present invention.
  • FIG. 1 is a schematic cross-sectional view showing a laminated structure of a general non-aqueous electrolyte secondary battery 10 including working electrodes when operated as a battery.
  • the non-aqueous electrolyte secondary battery 10 has a laminated structure having, when viewed from the negative electrode side, 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. is doing.
  • the space between the negative electrode active material layer and the positive electrode active material layer is filled with a non-aqueous electrolyte (not shown) and separated by the separator 3 .
  • the separator 3 has pores and functions as a positive/negative separator that insulates the positive/negative electrodes while permeating the electrolytic solution and ions under normal battery usage conditions.
  • a positive/negative separator that insulates the positive/negative electrodes while permeating the electrolytic solution and ions under normal battery usage conditions.
  • a light bulb is employed in the actuation portion 6, which is lit by the 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 non-aqueous secondary battery of the present invention comprises a positive electrode active material, a non-aqueous electrolyte, a solid electrolyte material, other members, etc., except that the negative electrode composition of the present invention is used to form a negative electrode active material layer.
  • a positive electrode active material a positive electrode active material
  • a non-aqueous electrolyte a solid electrolyte material
  • other members etc.
  • the negative electrode composition of the present invention is used to form a negative electrode active material layer.
  • the negative electrode composition of the present invention is used to form a negative electrode active material layer.
  • JP-A-2016-201308, JP-A-2005-108835, JP-A-2012-185938, and International Publication No. 2020/067106 can be referred to as appropriate.
  • the non-aqueous secondary battery of the present invention can be used, for example, in notebook computers, pen-input computers, mobile computers, e-book players, mobile phones, cordless phone slaves, pagers, handy terminals, mobile facsimiles, mobile copiers, mobile printers, and headphone stereos. , video movies, liquid crystal televisions, handy cleaners, portable CDs, minidiscs, electric shavers, transceivers, electronic notebooks, calculators, portable tape recorders, radios, backup power supplies, memory cards, and other electronic devices.
  • the weight average molecular weight (Mw) of the polymer shown in Table 1 below is the weight average molecular weight converted to sodium polyacrylate by gel permeation chromatography (GPC), and is a value measured under the following conditions.
  • Measuring instrument HLC-8220GPC (trade name, manufactured by Tosoh Corporation)
  • Guard column TSKgel guard column PWXL (trade name, manufactured by Tosoh Corporation)
  • Carrier 200 mM sodium nitrate aqueous solution
  • Rinse liquid Ultrapure water
  • Carrier flow rate Sample pump 1.0 mL/min Reference pump 0.223 mL/min Pump initial pressure: sample pump 4.4 MPa Reference pump 0.8MPa Sample concentration: 0.10% by mass
  • Detector RI (refractive index) detector
  • composition No. 1 in Table 1 below 30 parts by mass of carbon-coated silicon oxide (SiOC, carbon atom content ratio 1.3% by mass, average primary particle size: 5 ⁇ m, Osaka Titanium Co., Ltd.) in a 60 ml ointment container (manufactured by Umano Kagaku Co., Ltd.), 70 parts by mass of graphite (trade name: mag-d, manufactured by Hitachi Chemical Co., Ltd.), 5 parts by mass of acetylene black (trade name: Denka Black, manufactured by Denka), 5 parts by mass of polymer 1, 22.5 parts by mass of distilled water Parts by mass were added, and dispersed for 10 minutes at 2000 rpm using a foaming mixer (trade name, manufactured by THINKY).
  • a negative electrode composition 1 was obtained by adding 27 parts by mass of distilled water to the dispersed liquid and dispersing the mixture at 2000 rpm for 10 minutes using a bubble removing mixer.
  • compositions 2 to 19 and c1 to c3 compositions of Nos. 2 to 19 and c1 to c3 in Table 1 below.
  • the negative electrode composition was prepared in the same manner as the negative electrode composition 1, except that polymers 2 to 19 and c1 to c3 described in Table 1 below were used instead of the polymer 1. 2-19 and c1-c3 were prepared.
  • Lithium foil (thickness 50 ⁇ m, 14.5 mm ⁇ ) and polypropylene separator (thickness 25 ⁇ m, 16.0 mm ⁇ ) were stacked in this order. I let you in.
  • the separator was further impregnated with 200 ⁇ L of the electrolytic solution, and the negative electrode sheet was stacked so that the negative electrode active material layer surface was in contact with the separator.
  • the 2032 type coin case was crimped to prepare a non-aqueous electrolyte secondary battery 1 (a battery having a laminate consisting of Li foil-separator-negative electrode active material layer-copper foil).
  • Cycle characteristics were evaluated by repeating 50 charge/discharge cycles, with one charge/discharge cycle being defined as one charge/discharge cycle. Assuming that the discharge capacity at the first cycle after initialization (initial discharge capacity) is 100%, the discharge capacity retention rate at the 50th cycle (100 ⁇ “50th cycle discharge capacity” / “initial discharge capacity”) was calculated. , was applied to the following evaluation ranks, and the cycle characteristics were evaluated. The results are shown in Table 1 below. In this test, evaluation ranks "1" to "3" are passed. -Evaluation rank of discharge capacity retention rate (cycle characteristics)- 1: 95% or more 2: 90% or more and less than 95% 3: 85% or more and less than 90% 4: less than 85%
  • “Acid group content in polymer A (% by mass)” means the content of constituents having acid groups in polymer A.
  • Constent 1 (parts by mass)” When the content of SiOC in the negative electrode composition is 100 parts by mass, it means the content of polymer A with respect to 100 parts by mass of SiOC.
  • Constent in binder (% by mass) means the content of the water-soluble polymer defined in the present invention in the binder.
  • Constent 2 (parts by mass)” When the content of SiOC in the negative electrode composition is 100 parts by mass, it means the content of polymer B with respect to 100 parts by mass of SiOC.
  • content of “latex” is content of solid content. All Polymer A's, including those of the Comparative Examples, are water soluble.
  • No. Polymer A used in the negative electrode compositions of c1 and c3 contains more than 5% by mass of constituents having acid groups. No. Nos. c1 and c3 produced using the negative electrode compositions. Batteries of c1 and c3 were inferior in cycle characteristics.
  • No. Polymer A used in the negative electrode composition of c2 has a content of constituents having an acid group of 5% by mass or less, but a weight average molecular weight of more than 300,000. No. No. c2 produced using the negative electrode composition. The battery of c2 was inferior in cycle characteristics. On the other hand, it can be seen that the batteries (Nos. 1 to 19) produced using the negative electrode compositions (Nos. 1 to 19) of the present invention are excellent in cycle characteristics.

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Abstract

La présente invention concerne une composition pour une électrode négative comprenant un liant et de l'oxyde de silicium revêtu de carbone, le liant comprenant 5 % en masse ou plus d'un polymère soluble dans l'eau, le polymère soluble dans l'eau a un poids moléculaire moyen en poids de 300 000 ou moins, et la proportion d'un composant contenant un groupe acide dans le polymère soluble dans l'eau est de 5 % en masse ou moins, ainsi qu'une feuille d'électrode négative et une batterie secondaire non aqueuse produites à l'aide de cette composition pour une électrode négative, et un procédé de fabrication de la feuille d'électrode négative et de la batterie secondaire non aqueuse.
PCT/JP2022/015556 2021-03-31 2022-03-29 Composition pour électrode négative, feuille d'électrode négative, batterie secondaire non aqueuse, et procédé de fabrication de feuille d'électrode négative et de batterie secondaire non aqueuse WO2022210738A1 (fr)

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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2013051203A (ja) * 2011-08-04 2013-03-14 Nippon Zeon Co Ltd 電気化学素子電極用複合粒子、電気化学素子電極材料、電気化学素子電極、及び電気化学素子
JP2013084351A (ja) * 2011-10-06 2013-05-09 Nippon Zeon Co Ltd 電気化学素子電極用複合粒子、電気化学素子電極材料、及び電気化学素子電極
JP2013179059A (ja) * 2009-05-11 2013-09-09 Nexeon Ltd リチウムイオン再充電可能電池セル
WO2018155609A1 (fr) * 2017-02-23 2018-08-30 日本電気株式会社 Accumulateur au lithium-ion comprenant une électrode négative pour batterie à haute densité d'énergie

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2013179059A (ja) * 2009-05-11 2013-09-09 Nexeon Ltd リチウムイオン再充電可能電池セル
JP2013051203A (ja) * 2011-08-04 2013-03-14 Nippon Zeon Co Ltd 電気化学素子電極用複合粒子、電気化学素子電極材料、電気化学素子電極、及び電気化学素子
JP2013084351A (ja) * 2011-10-06 2013-05-09 Nippon Zeon Co Ltd 電気化学素子電極用複合粒子、電気化学素子電極材料、及び電気化学素子電極
WO2018155609A1 (fr) * 2017-02-23 2018-08-30 日本電気株式会社 Accumulateur au lithium-ion comprenant une électrode négative pour batterie à haute densité d'énergie

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