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WO2025033218A1 - Liant pour électrodes de batterie secondaire et son utilisation - Google Patents

Liant pour électrodes de batterie secondaire et son utilisation Download PDF

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Publication number
WO2025033218A1
WO2025033218A1 PCT/JP2024/026789 JP2024026789W WO2025033218A1 WO 2025033218 A1 WO2025033218 A1 WO 2025033218A1 JP 2024026789 W JP2024026789 W JP 2024026789W WO 2025033218 A1 WO2025033218 A1 WO 2025033218A1
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Prior art keywords
secondary battery
mass
monomer
binder
meth
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English (en)
Japanese (ja)
Inventor
健吾 山田
大貴 市川
剛史 長谷川
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Toagosei Co Ltd
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Toagosei Co Ltd
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Classifications

    • 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
    • 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
    • C08F222/00—Copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a carboxyl radical and containing at least one other carboxyl radical in the molecule; Salts, anhydrides, esters, amides, imides, or nitriles thereof
    • C08F222/02—Acids; Metal salts or ammonium salts thereof, e.g. maleic acid or itaconic acid
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L1/00—Compositions of cellulose, modified cellulose or cellulose derivatives
    • C08L1/08—Cellulose derivatives
    • 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
    • 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
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Definitions

  • the present invention relates to a binder for secondary battery electrodes and its use.
  • the electrodes used in these secondary batteries are produced by applying a composition for forming an electrode mixture layer containing an active material and a binder, etc., to a current collector and drying it.
  • a composition for forming an electrode mixture layer containing an active material and a binder, etc. for example, an aqueous binder containing styrene butadiene rubber (SBR) latex and carboxymethyl cellulose (CMC) is used as the binder for the negative electrode mixture layer composition.
  • SBR styrene butadiene rubber
  • CMC carboxymethyl cellulose
  • an organic solvent-based binder such as a solution of polyvinylidene fluoride (PVDF) in N-methyl-2-pyrrolidone (NMP) is widely used as the binder for the positive electrode mixture layer composition.
  • PVDF polyvinylidene fluoride
  • NMP N-methyl-2-pyrrolidone
  • Patent Document 1 discloses a binder containing a cross-linked acrylic acid polymer obtained by cross-linking polyacrylic acid with a specific cross-linking agent, and discloses that even when an active material containing silicon (hereinafter also referred to as a "silicon-based active material") is used, the electrode structure is not destroyed and good cycle characteristics are exhibited.
  • silicon-based active material an active material containing silicon
  • Patent Document 2 also discloses a binder containing a non-crosslinked acrylic acid polymer consisting of a salt of acrylic acid or an acrylic acid derivative and acrylonitrile or an acrylonitrile derivative, and discloses that the binder can follow the expansion and contraction of the silicon-based active material, thereby improving cycle characteristics.
  • the binders for secondary battery electrodes disclosed in Patent Documents 1 and 2 can provide good binding properties, when the ratio of silicon-based active material is increased to improve the performance of the secondary battery, the cycle characteristics may be insufficient, and further, the DC resistance (hereinafter also referred to as "internal resistance") after the first charge and discharge of the secondary battery may be high, which may be problematic.
  • the present invention has been made in view of the above circumstances, and its purpose is to provide a binder for secondary battery electrodes that can reduce the internal resistance of secondary batteries and improve cycle characteristics.
  • the present invention also provides a composition for secondary battery electrode mixture layers that contains the binder, and a secondary battery electrode and secondary battery obtained using the composition.
  • the polymer has structural units derived from three specific types of monomers, which makes it possible to reduce the internal resistance of the secondary battery while improving its cycle characteristics, and thus completed the present invention.
  • a binder for a secondary battery electrode comprising a lithium salt of a carboxyl group-containing non-crosslinked polymer
  • the carboxyl group-containing non-crosslinked polymer is a binder for a secondary battery electrode, comprising a structural unit derived from an ethylenically unsaturated carboxylic acid monomer (hereinafter also referred to as "monomer (a)”), a structural unit derived from an amide group-containing ethylenically unsaturated monomer (hereinafter also referred to as “monomer (b)”), and a structural unit derived from a nitrile group-containing ethylenically unsaturated monomer (hereinafter also referred to as "monomer (c)”).
  • the lithium salt of the carboxyl group-containing non-crosslinked polymer is a salt in which 40 mol % or more of the carboxyl groups of the non-crosslinked polymer are neutralized.
  • the binder for secondary battery electrodes according to any one of [1] to [3].
  • a composition for a secondary battery electrode mixture layer comprising the binder for a secondary battery electrode according to any one of [1] to [4], an active material, and water.
  • the secondary battery electrode mixture layer composition according to [5] further comprising carboxymethyl cellulose (CMC).
  • CMC carboxymethyl cellulose
  • a secondary battery electrode comprising a mixture layer formed on a surface of a current collector from the composition for a secondary battery electrode mixture layer according to [5] or [6].
  • a secondary battery comprising the secondary battery electrode according to [7].
  • the secondary battery electrode binder of the present invention makes it possible to obtain a secondary battery with low internal resistance and excellent cycle characteristics.
  • the binder for secondary battery electrodes of the present invention contains a lithium salt of a carboxyl group-containing non-crosslinked polymer (hereinafter also referred to as “the non-crosslinked polymer”) having a structural unit derived from a monomer (a), a structural unit derived from a monomer (b), and a structural unit derived from a monomer (c), and can be mixed with an active material and water to form a composition for secondary battery electrode mixture layer (hereinafter also referred to as "the composition”).
  • the non-crosslinked polymer having a structural unit derived from a monomer (a), a structural unit derived from a monomer (b), and a structural unit derived from a monomer (c)
  • the above composition is preferably an electrode slurry in a slurry state that can be applied to a current collector in terms of achieving the effects of the present invention, but it may be prepared in a wet powder state so that it can be applied to the current collector surface for press processing.
  • the secondary battery electrode of the present invention is obtained by forming a mixture layer formed from the above composition on the surface of a current collector such as copper foil or aluminum foil.
  • the present binder is preferable in that when it is used in a secondary battery electrode mixture layer composition containing a silicon-based active material described below as an active material, the effects of the present invention are particularly large.
  • (meth)acrylic means acrylic and/or methacrylic
  • (meth)acrylate means acrylate and/or methacrylate
  • (meth)acryloyl group means acryloyl group and/or methacryloyl group.
  • the lithium salt of the carboxyl group-containing non-crosslinked polymer of the present invention can be introduced into the non-crosslinked polymer by polymerizing monomer components including monomer (a), monomer (b) and monomer (c), which has a structural unit derived from monomer (a), a structural unit derived from monomer (b) and a structural unit derived from monomer (c).
  • the non-crosslinked polymer has a structural unit (hereinafter, also referred to as "component (a)”) derived from an ethylenically unsaturated carboxylic acid monomer (monomer (a)).
  • component (a) derived from an ethylenically unsaturated carboxylic acid monomer (monomer (a)).
  • the above-mentioned (a) component can be introduced into the non-crosslinked polymer by, for example, polymerizing the monomer (a). Alternatively, it can be obtained by (co)polymerizing a (meth)acrylic acid ester monomer and then hydrolyzing it. In addition, it may be obtained by polymerizing (meth)acrylamide and (meth)acrylonitrile, etc., and then treating them with a strong alkali, or by reacting a polymer having a hydroxyl group with an acid anhydride.
  • Examples of the monomer (a) include (meth)acrylic acid, itaconic acid, crotonic acid, maleic acid, and fumaric acid; (meth)acrylamidoalkyl carboxylic acids such as (meth)acrylamidohexanoic acid and (meth)acrylamidododecanoic acid; and carboxyl group-containing ethylenically unsaturated monomers such as monohydroxyethyl succinate (meth)acrylate, ⁇ -carboxy-caprolactone mono(meth)acrylate, and ⁇ -carboxyethyl (meth)acrylate, or (partially) alkali-neutralized products thereof.
  • One of these may be used alone, or two or more may be used in combination.
  • compounds having an acryloyl group as a polymerizable functional group are preferred, in that they have a high polymerization rate, resulting in a polymer with a long primary chain length, and the binding strength of the binder is good, and acrylic acid is particularly preferred.
  • acrylic acid is used as the ethylenically unsaturated carboxylic acid monomer, a polymer with a high carboxyl group content can be obtained.
  • the content of component (a) in the non-crosslinked polymer can be 40% by mass or more and 98% by mass or less based on the total structural units of the non-crosslinked polymer.
  • component (a) in this range, excellent adhesion to the current collector can be easily ensured, and the cycle characteristics of the secondary battery can be improved.
  • the lower limit is 40% by mass or more, the dispersion stability of the composition becomes good and a higher binding force can be obtained, which is preferable, and the lower limit may be 50% by mass or more, 60% by mass or more, 70% by mass or more, or 80% by mass or more.
  • the upper limit is, for example, 97% by mass or less, for example, 96% by mass or less, for example, 95% by mass or less, for example, 93% by mass or less, for example, 91% by mass or less, or for example, 90% by mass or less.
  • the non-crosslinked polymer has a structural unit (hereinafter, also referred to as "component (b)") derived from an amide group-containing ethylenically unsaturated monomer (monomer (b)).
  • component (b) derived from an amide group-containing ethylenically unsaturated monomer (monomer (b)).
  • the non-crosslinked polymer has such a structural unit, and thus has excellent cycle characteristics of a secondary battery.
  • the above-mentioned (b) component can be introduced into the present non-crosslinked polymer by polymerizing a monomer containing the monomer (b).
  • Examples of the monomer (b) include (meth)acrylamide, a monomer represented by the following formula (1), and (meth)acrylamide derivatives (monomers other than the monomer represented by the following formula (1)).
  • (meth)acrylamide is preferred because it provides better cycle characteristics for secondary batteries.
  • R5 represents a hydrogen atom or a methyl group
  • R6 represents a hydroxyl group or a hydroxyalkyl group having 1 to 8 carbon atoms
  • R7 represents a hydrogen atom or a monovalent organic group.
  • the monomer represented by the above formula (1) is a (meth)acrylamide derivative having a hydroxyl group or a hydroxyalkyl group having 1 to 8 carbon atoms.
  • R 7 represents a hydrogen atom or a monovalent organic group.
  • the monovalent organic group is not particularly limited, but examples thereof include an alkyl group that may have a linear, branched, or cyclic structure, as well as an aryl group and an alkoxyalkyl group, and is preferably an organic group having 1 to 8 carbon atoms.
  • R 7 may be a hydroxyl group or a hydroxyalkyl group having 1 to 8 carbon atoms.
  • Examples of the monomer represented by the above formula (1) include hydroxy(meth)acrylamide; (meth)acrylamide derivatives having a hydroxyalkyl group having 1 to 8 carbon atoms, such as N-hydroxyethyl(meth)acrylamide, N-(2-hydroxypropyl)(meth)acrylamide, N-hydroxybutyl(meth)acrylamide, N-hydroxyhexyl(meth)acrylamide, N-hydroxyoctyl(meth)acrylamide, N-methylhydroxyethyl(meth)acrylamide, and N-ethylhydroxyethyl(meth)acrylamide; and N,N-dihydroxyalkyl(meth)acrylamides, such as N,N-dihydroxyethyl(meth)acrylamide and N,N-dihydroxyethyl(meth)acrylamide.
  • the monomer represented by the above formula (1) may be used alone or in combination of two or more.
  • (meth)acrylamide derivatives having a hydroxyalkyl group having 1 to 8 carbon atoms are more preferred, and N-hydroxyethyl(meth)acrylamide, N-(2-hydroxypropyl)(meth)acrylamide, and N-hydroxybutyl(meth)acrylamide are even more preferred.
  • Examples of (meth)acrylamide derivatives include N-alkyl (meth)acrylamide compounds such as N-isopropyl (meth)acrylamide and N-t-butyl (meth)acrylamide; N-alkoxyalkyl (meth)acrylamide compounds such as N-n-butoxymethyl (meth)acrylamide and N-isobutoxymethyl (meth)acrylamide; and N,N-dialkyl (meth)acrylamide compounds such as N,N-dimethyl (meth)acrylamide and N,N-diethyl (meth)acrylamide. One of these may be used alone, or two or more may be used in combination.
  • the content of component (b) in the non-crosslinked polymer may be 1% by mass or more and 50% by mass or less based on the total structural units of the non-crosslinked polymer. By including component (b) in this range, excellent adhesion to the current collector can be easily ensured, and the cycle characteristics of the secondary battery can be improved.
  • the lower limit is 1% by mass or more, the dispersion stability of the composition is good and a higher binding strength can be obtained, which is preferable, and it may be 2% by mass or more, 3% by mass or more, or 5% by mass or more.
  • the upper limit is, for example, 49% by mass or less, 45% by mass or less, for example, 40% by mass or less, for example, 30% by mass or less, for example, 20% by mass or less, or for example, 10% by mass or less.
  • the non-crosslinked polymer has a structural unit (hereinafter, also referred to as "component (c)”) derived from a nitrile group-containing ethylenically unsaturated monomer (monomer (c)).
  • component (c) derived from a nitrile group-containing ethylenically unsaturated monomer (monomer (c)).
  • the non-crosslinked polymer has such a structural unit, and thus the secondary battery has excellent cycle characteristics.
  • the above component (c) can be introduced into the present non-crosslinked polymer by polymerizing a monomer containing the monomer (c).
  • Examples of monomer (c) include (meth)acrylonitrile; (meth)acrylic acid cyanoalkyl ester compounds such as cyanomethyl (meth)acrylate and cyanoethyl (meth)acrylate; cyano group-containing unsaturated aromatic compounds such as 4-cyanostyrene and 4-cyano- ⁇ -methylstyrene; vinylidene cyanide; and the like.
  • acrylonitrile is preferred because it has a high nitrile group content and provides better cycle characteristics for secondary batteries.
  • the content of component (c) in the non-crosslinked polymer can be 1% by mass or more and 50% by mass or less based on the total structural units of the non-crosslinked polymer. By including component (c) in this range, excellent adhesion to the current collector can be easily ensured, and the cycle characteristics of the secondary battery can be improved.
  • the lower limit is 1% by mass or more, the dispersion stability of the composition becomes good and a higher binding strength can be obtained, which is preferable, and the lower limit may be 3% by mass or more, 5% by mass or more, 10% by mass or more, 15% by mass or more, 20% by mass or more, or 25% by mass or more.
  • the upper limit is, for example, 45% by mass or less, 40% by mass or less, or, for example, 35% by mass or less, or, for example, 30% by mass or less.
  • the non-crosslinked polymer may contain a structural unit derived from another ethylenically unsaturated monomer copolymerizable therewith (hereinafter also referred to as “component (d)").
  • component (d) examples include structural units derived from hydroxyl-containing ethylenically unsaturated monomers (monomers represented by the following formula (2)), ethylenically unsaturated monomer compounds having anionic groups other than carboxyl groups such as sulfonic acid groups and phosphoric acid groups, or nonionic ethylenically unsaturated monomers (excluding monomers classified as nitrogen-containing ethylenically unsaturated monomers).
  • monomers represented by the following formula (2) ethylenically unsaturated monomer compounds having anionic groups other than carboxyl groups such as sulfonic acid groups and phosphoric acid groups
  • nonionic ethylenically unsaturated monomers excluding monomers classified as nitrogen-containing ethylenically unsaturated monomers.
  • These structural units can be introduced by copolymerizing monomers including hydroxyl-containing ethylenically unsaturated monomers, ethylenically unsaturated monomer compounds having anionic groups other than carboxyl groups such as sulfonic acid groups and phosphoric acid groups, or nonionic ethylenically unsaturated monomers.
  • CH 2 C(R 1 )COOR 2 (2)
  • R 1 represents a hydrogen atom or a methyl group
  • R 2 represents a monovalent organic group having 1 to 8 carbon atoms and a hydroxyl group, (R 3 O) m H or R 4 O[CO(CH 2 ) 5 O] n H.
  • R 3 represents an alkylene group having 2 to 4 carbon atoms
  • R 4 represents an alkylene group having 1 to 8 carbon atoms
  • m represents an integer of 2 to 15
  • n represents an integer of 1 to 15.
  • the proportion of the (d) component can be 0% by mass or more and 50% by mass or less with respect to the total structural units of the non-crosslinked polymer.
  • the proportion of the (d) component may be 0.1% by mass or more and 45% by mass or less, 0.5% by mass or more and 40% by mass or less, 1.0% by mass or more and 30% by mass or less, 5.0% by mass or more and 20% by mass or less, or 3% by mass or more and 10% by mass or less.
  • the affinity to the electrolyte is improved, and therefore the effect of improving lithium ion conductivity can also be expected.
  • the (d) component is preferably a hydroxyl group-containing ethylenically unsaturated monomer, since it provides excellent binding properties to the binder containing the lithium salt of the non-crosslinked polymer.
  • the monomer represented by the formula (2) is a (meth)acrylate compound having a hydroxyl group.
  • R 2 is a monovalent organic group having 1 to 8 carbon atoms having a hydroxyl group, the number of the hydroxyl groups may be only one or may be two or more.
  • the monovalent organic group is not particularly limited, and examples thereof include an alkyl group that may have a linear, branched or cyclic structure, an aryl group and an alkoxyalkyl group.
  • R 2 is (R 3 O) m H or R 4 O[CO(CH 2 ) 5 O] n H
  • the alkylene group represented by R 3 or R 4 may be linear or branched.
  • Examples of monomers represented by the above formula (2) include hydroxyalkyl (meth)acrylates having a hydroxyalkyl group having 1 to 8 carbon atoms, such as 2-hydroxyethyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, hydroxyhexyl (meth)acrylate, and hydroxyoctyl (meth)acrylate; polyalkylene glycol mono(meth)acrylates, such as polyethylene glycol mono(meth)acrylate, polypropylene glycol mono(meth)acrylate, polybutylene glycol mono(meth)acrylate, and polyethylene glycol-polypropylene glycol mono(meth)acrylate; dihydroxyalkyl (meth)acrylates, such as glycerin mono(meth)acrylate; caprolactone-modified hydroxymethacrylates (manufactured by Daicel Corporation, product names "Placcel FM1", "Placcel FM5", etc.
  • a structural unit derived from a nonionic ethylenically unsaturated monomer is preferred.
  • the nonionic ethylenically unsaturated monomer include alicyclic structure-containing ethylenically unsaturated monomers.
  • Examples of the alicyclic structure-containing ethylenically unsaturated monomer include (meth)acrylic acid cycloalkyl esters which may have an aliphatic substituent, such as cyclopentyl (meth)acrylate, cyclohexyl (meth)acrylate, methylcyclohexyl (meth)acrylate, t-butylcyclohexyl (meth)acrylate, cyclodecyl (meth)acrylate, and cyclododecyl (meth)acrylate; isobornyl (meth)acrylate, adamantyl (meth)acrylate, cyclopentenyl (meth)acrylate, dicyclopentenyloxyethyl (meth)acrylate, dicyclopentanyl (meth)acrylate, and cycloalkyl polyalcohol mono(meth)acrylates such as cyclohexanedimethanol mono(meth)acrylate and cyclode
  • the lithium salt of the non-crosslinked polymer preferably contains a structural unit derived from a monomer represented by the above formula (2), an alicyclic structure-containing ethylenically unsaturated monomer, etc.
  • a structural unit derived from a monomer represented by the above formula (2) is more preferable in view of the excellent effect of improving the binding property of the binder.
  • hydroxyalkyl (meth)acrylates having a hydroxyalkyl group having 1 to 8 carbon atoms are more preferred, and 2-hydroxyethyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate are even more preferred.
  • component (d) when a structural unit derived from a hydrophobic ethylenically unsaturated monomer having a solubility in water of 1 g/100 ml or less is introduced as component (d), it is possible to achieve a strong interaction with the electrode material and to exhibit good binding properties to the active material. This makes it possible to obtain a robust electrode mixture layer with good integrity, and therefore, as the above-mentioned "hydrophobic ethylenically unsaturated monomer having a solubility in water of 1 g/100 ml or less", an alicyclic structure-containing ethylenically unsaturated monomer is particularly preferred.
  • (meth)acrylic acid esters may be used.
  • the (meth)acrylic acid esters include (meth)acrylic acid alkyl ester compounds such as methyl (meth)acrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate;
  • Aromatic (meth)acrylic acid ester compounds such as phenyl (meth)acrylate, phenylmethyl (meth)acrylate, phenylethyl (meth)acrylate, and phenoxyethyl (meth)acrylate
  • alkoxyalkyl ester compounds include (meth)acrylic acid alkoxyalkyl ester compounds such as 2-methoxyethyl (meth)acrylate and 2-ethoxyethyl (meth)acrylate.
  • aromatic (meth)acrylic acid ester compounds can be preferably used.
  • compounds having an ether bond such as (meth)acrylic acid alkoxyalkyl esters such as 2-methoxyethyl (meth)acrylate and 2-ethoxyethyl (meth)acrylate, are preferred, with 2-methoxyethyl (meth)acrylate being more preferred.
  • non-ionic ethylenically unsaturated monomers compounds having an acryloyl group are preferred because they have a fast polymerization rate, resulting in a polymer with a long primary chain length, and because they provide good binding strength for the binder.
  • compounds whose homopolymer glass transition temperature (Tg) is 0°C or less are preferred because they provide good bending resistance for the resulting electrode.
  • the lithium salt of this non-crosslinked polymer is in the form of a salt in which some or all of the carboxyl groups contained in the polymer have been neutralized.
  • the secondary battery has excellent cycle characteristics, particularly excellent low-temperature battery characteristics.
  • the present non-crosslinked polymer is preferably used in the present composition as a lithium salt in which an acid group such as a carboxyl group derived from an ethylenically unsaturated carboxylic acid monomer is neutralized so that the degree of neutralization is 40 mol% or more.
  • an acid group such as a carboxyl group derived from an ethylenically unsaturated carboxylic acid monomer is neutralized so that the degree of neutralization is 40 mol% or more.
  • the degree of neutralization is 40 mol% or more, it is preferable in that a dispersion stabilization effect is easily obtained.
  • the degree of neutralization is more preferably 50 mol% or more, even more preferably 70 mol% or more, even more preferably 75 mol% or more, even more preferably 80 mol% or more, and particularly preferably 85 mol% or more, in terms of being able to exhibit a superior charge/discharge capacity retention rate in long-term use compared to conventional methods.
  • the upper limit of the degree of neutralization is 100 mol%, and may be 98 mol% or 95 mol%.
  • the degree of neutralization can be calculated from the amount of monomer having an acid group such as a carboxyl group and the amount of neutralizing agent used for neutralization.
  • the number average molecular weight (Mn) of the lithium salt of the non- crosslinked polymer is measured as a value calculated as sodium polyacrylate according to aqueous gel permeation chromatography (GPC) described in the examples.
  • Mn is preferably 4,000 to 200,000 in terms of improving the dispersibility of the active material and exhibiting an excellent charge/discharge capacity retention rate, and can be adjusted by the monomer concentration and the amount of initiator.
  • Mn is more preferably 5,000 or more and 150,000 or less, further preferably 7,500 or more and 100,000 or less, and even more preferably 10,000 or more and 50,000 or less.
  • the weight average molecular weight (Mw) of the lithium salt of the non-crosslinked polymer is measured as a value calculated as sodium polyacrylate according to aqueous GPC described in the Examples.
  • the Mw is preferably 500,000 or more and 4,000,000 or less in terms of improving the binding property with the active material and the current collector and exhibiting an excellent charge/discharge capacity retention rate, and can be adjusted by the monomer concentration and the amount of the initiator.
  • the Mw is more preferably 600,000 or more and 3,500,000 or less, even more preferably 700,000 or more and 3,000,000 or less, still more preferably 800,000 or more and 2,500,000 or less, and even more preferably 900,000 or more and 2,000,000 or less.
  • the molecular weight distribution (Mw/Mn) of the lithium salt of the present non-crosslinked polymer is preferably from 5 to 300, in terms of improving the binding property with the active material and the current collector and the dispersibility of the active material and exhibiting an excellent charge/discharge capacity retention rate, and can be adjusted by the monomer concentration and the polymerization temperature.
  • Mw/Mn is more preferably 10 or more and 300 or less, even more preferably 20 or more and 290 or less, even more preferably 30 or more and 280 or less, even more preferably 40 or more and 270 or less, and particularly preferably 50 or more and 260 or less.
  • the present non-crosslinked polymer can be obtained by a method for polymerizing a monomer component including the monomer (a), the monomer (b) and the monomer (c).
  • the polymerization method may be bulk polymerization without using a solvent, solution polymerization in a solvent system, emulsion polymerization in a water system, mini-emulsion polymerization, suspension polymerization, etc.
  • solution polymerization is preferred because it can dissolve the present non-crosslinked polymer or its lithium salt uniformly and can be easily dispersed when added to the composition for electrode mixture layer in a slurry state.
  • water is preferred from the viewpoint of being able to uniformly dissolve the monomer (a), the monomer (b) and the monomer (c) and polymerize them.
  • water-soluble solvents include methanol, t-butyl alcohol, acetone, methyl ethyl ketone, acetonitrile, tetrahydrofuran, and the like, as well as benzene, ethyl acetate, dichloroethane, n-hexane, cyclohexane, n-heptane, and the like, and these can be used alone or in combination of two or more. Alternatively, these can be used as a mixed solvent with water.
  • the water-soluble solvent refers to a solvent having a solubility in water at 20° C. of more than 10 g/100 ml.
  • a highly polar solvent is preferably water and methanol.
  • the amount of the highly polar solvent used is preferably 0.05 to 20.0 mass% based on the total mass of the medium, more preferably 0.1 to 10.0 mass%, even more preferably 0.1 to 5.0 mass%, and even more preferably 0.1 to 1.0 mass%. If the proportion of the highly polar solvent is 0.05 mass% or more, an effect on the neutralization reaction is observed, and if it is 20.0 mass% or less, no adverse effect on the polymerization reaction is observed.
  • the polymerization rate is increased when a highly polar solvent is added, making it easier to obtain a polymer with a long primary chain length.
  • a highly polar solvent water is particularly preferable because it has a large effect of improving the polymerization rate.
  • the polymerization initiator may be any known polymerization initiator such as an azo compound, organic peroxide, or inorganic peroxide, but is not particularly limited.
  • the conditions of use can be adjusted so that an appropriate amount of radicals is generated using known methods such as thermal initiation, redox initiation using a reducing agent, or UV initiation. To obtain a non-crosslinked polymer with a long primary chain length, it is preferable to set the conditions so that the amount of radicals generated is as small as possible within the allowable range of production time.
  • the polymerization initiator in the aqueous solution polymerization is preferably a water-soluble polymerization initiator, and examples thereof include a compound having a hydrophilic group (e.g., a carboxyl group) and/or a salt or hydrate thereof.
  • the preferred amount of polymerization initiator used is, for example, 0.001 to 3 parts by mass, or, for example, 0.005 to 2.5 parts by mass, or, for example, 0.01 to 2 parts by mass, when the total amount of the monomer components used is taken as 100 parts by mass. If the amount of polymerization initiator used is 0.001 parts by mass or more, the polymerization reaction can be carried out stably, and if it is 1.5 parts by mass or less, a polymer with a long primary chain length is easily obtained.
  • the polymerization temperature depends on the type and concentration of the monomers used, but is preferably 0 to 100°C, more preferably 20 to 80°C.
  • the polymerization temperature may be constant or may vary over the course of the polymerization reaction.
  • the polymerization time is preferably 1 minute to 20 hours, more preferably 1 hour to 10 hours.
  • the non-crosslinked polymer may contain, relative to its total structural units, 40% by mass or more and 98% by mass or less of structural units derived from monomer (a), 1% by mass or more and 50% by mass or less of structural units derived from monomer (b), and 1% by mass or more and 50% by mass or less of structural units derived from monomer (c), and the preferred ranges of the contents of the structural units are as described above.
  • the types of monomer (a), monomer (b), and monomer (c) are as described above.
  • composition for secondary battery electrode mixture layer of the present invention contains the present binder, an active material, and water.
  • the amount of the binder used in the composition is preferably 0.5 parts by mass or more and 7.0 parts by mass or less with respect to 100 parts by mass of the total amount of the active material.
  • the amount is, for example, 0.8 parts by mass or more and 3.0 parts by mass or less, for example, 1.0 parts by mass or more and 2.5 parts by mass or less, and for example, 1.2 parts by mass or more and 1.5 parts by mass or less.
  • the amount of the binder used is 0.5 parts by mass or more, sufficient binding property can be obtained.
  • the dispersion stability of the active material and the like can be ensured, and a uniform mixture layer can be formed.
  • the amount of the binder used is 1.5 parts by mass or less, the composition does not become highly viscous, and the coatability to the current collector can be ensured. As a result, a mixture layer having a uniform and smooth surface can be formed.
  • the positive electrode active material can be a lithium salt of a transition metal oxide, for example, a layered rock salt type and a spinel type lithium-containing metal oxide can be used.
  • a spinel type positive electrode active material lithium manganate and the like can be mentioned.
  • phosphates In addition to oxides, phosphates, silicates, sulfur, and the like can be used, and as a phosphate, olivine type lithium iron phosphate and the like can be mentioned.
  • the positive electrode active material one of the above may be used alone, or two or more may be combined and used as a mixture or composite.
  • a positive electrode active material containing a layered rock salt type lithium-containing metal oxide When a positive electrode active material containing a layered rock salt type lithium-containing metal oxide is dispersed in water, the lithium ions on the active material surface are exchanged with hydrogen ions in the water, causing the dispersion to become alkaline. This may cause corrosion of aluminum foil (Al), which is a common positive electrode current collector material. In such cases, it is preferable to neutralize the alkali content eluted from the active material by using the present non-crosslinked polymer that has been unneutralized or partially neutralized as a binder.
  • the present non-crosslinked polymer that has been unneutralized or partially neutralized in an amount such that the amount of unneutralized carboxyl groups in the present non-crosslinked polymer is equivalent to or greater than the amount of alkali eluted from the active material.
  • a conductive assistant other than carbon nanotubes may be added.
  • the conductive assistant include carbon-based materials such as carbon black, carbon fiber, graphite powder, and carbon fiber. Of these, carbon black and carbon fiber are preferred because they are easy to obtain excellent conductivity. As carbon black, ketjen black and acetylene black are preferred.
  • the conductive assistant may be one of the above alone or two or more may be used in combination.
  • the amount of the conductive assistant other than carbon nanotubes may be, for example, 0.2 to 20 parts by mass, or, for example, 0.2 to 10 parts by mass, per 100 parts by mass of the total active material, from the viewpoint of achieving both electrical conductivity and energy density.
  • the positive electrode active material may be surface-coated with a carbon-based material having electrical conductivity.
  • examples of the negative electrode active material include carbon-based materials, lithium metal, lithium alloys, and metal oxides, and one or more of these can be used in combination.
  • active materials made of carbon-based materials such as natural graphite, artificial graphite, hard carbon, and soft carbon (hereinafter also referred to as "carbon-based active materials") are preferred, and graphite such as natural graphite and artificial graphite, and hard carbon are more preferred.
  • graphite spherical graphite is preferably used from the viewpoint of battery performance, and the preferred range of the particle size is, for example, 1 to 20 ⁇ m, and, for example, 5 to 15 ⁇ m.
  • silicon has a higher capacity than graphite
  • active materials made of silicon-based materials such as silicon, silicon alloys, and silicon oxides such as silicon monoxide (SiO) (hereinafter also referred to as "silicon-based active materials") can be used.
  • the amount of silicon-based active material used is 5.0% by mass or more, for example, 10.0% by mass or more, and can be, for example, 20.0% by mass or more, based on the total amount of active materials, from the viewpoint of improving the electric capacity of the secondary battery.
  • the amount used is, from the viewpoint of energy density, for example, 10 parts by mass or less, and for example, 5 parts by mass or less, per 100 parts by mass of the total amount of active material.
  • the amount of active material used is, for example, in the range of 10 to 75 mass %, or, for example, in the range of 30 to 65 mass %, based on the total amount of the composition. If the amount of active material used is 10 mass % or more, migration of binders and the like is suppressed, and it is also advantageous in terms of the cost of drying the medium. On the other hand, if it is 75 mass % or less, the fluidity and coatability of the composition can be ensured, and a uniform mixture layer can be formed.
  • This composition uses water as a medium.
  • it may be mixed with lower alcohols such as methanol and ethanol, carbonates such as ethylene carbonate, ketones such as acetone, tetrahydrofuran, N-methyl-2-pyrrolidone, and other water-soluble organic solvents.
  • the proportion of water in the mixed medium is, for example, 50% by mass or more, and, for example, 70% by mass or more.
  • the content of the water-containing medium in the entire composition can be, for example, in the range of 25 to 60 mass %, and can be, for example, 35 to 60 mass %, from the viewpoints of the coatability of the slurry, the energy cost required for drying, and productivity.
  • the composition may further contain other binder components such as styrene butadiene rubber (SBR) latex, carboxymethyl cellulose (CMC), acrylic latex, and polyvinylidene fluoride latex.
  • SBR styrene butadiene rubber
  • CMC carboxymethyl cellulose
  • acrylic latex acrylic latex
  • polyvinylidene fluoride latex polyvinylidene fluoride latex.
  • the amount of the binder components used may be, for example, 0.1 to 5 parts by mass or less, or, for example, 0.1 to 2 parts by mass or less, or, for example, 0.1 to 1 part by mass or less, relative to 100 parts by mass of the total amount of the active material. If the amount of the other binder components used exceeds 5 parts by mass, the resistance increases and the high-rate characteristics may become insufficient.
  • SBR latex and CMC are preferred in terms of the excellent balance between binding strength and flex resistance, and it is more preferable to use SBR latex and CMC
  • the SBR latex refers to an aqueous dispersion of a copolymer having structural units derived from an aromatic vinyl monomer such as styrene and structural units derived from an aliphatic conjugated diene monomer such as 1,3-butadiene.
  • aromatic vinyl monomer include ⁇ -methylstyrene, vinyltoluene, divinylbenzene, and the like, in addition to styrene, and one or more of these can be used.
  • the structural units derived from the aromatic vinyl monomer in the copolymer can be, for example, in the range of 20 to 70% by mass, or, for example, in the range of 30 to 60% by mass, mainly from the viewpoint of binding properties.
  • Examples of the aliphatic conjugated diene monomer include 2-methyl-1,3-butadiene, 2,3-dimethyl-1,3-butadiene, 2-chloro-1,3-butadiene, and the like in addition to 1,3-butadiene, and one or more of these can be used.
  • the structural unit derived from the aliphatic conjugated diene monomer in the copolymer can be in the range of, for example, 30 to 70% by mass, or, for example, 40 to 60% by mass, in terms of improving the binding property of the binder and the flexibility of the resulting electrode.
  • the styrene/butadiene-based latex may use other monomers as copolymerization monomers, such as nitrile group-containing monomers such as (meth)acrylonitrile, carboxyl group-containing monomers such as (meth)acrylic acid, itaconic acid, maleic acid, and ester group-containing monomers such as methyl (meth)acrylate, in order to further improve performance such as binding property.
  • the content of the structural units derived from the other monomers in the copolymer can be, for example, in the range of 0 to 30% by mass, and can be, for example, in the range of 0 to 20% by mass.
  • the above CMC refers to a nonionic cellulose-based semisynthetic polymer compound substituted with a carboxymethyl group and its salt.
  • the nonionic cellulose-based semisynthetic polymer compound include alkyl celluloses such as methyl cellulose, methyl ethyl cellulose, ethyl cellulose, and microcrystalline cellulose; hydroxyethyl cellulose, hydroxybutyl methyl cellulose, hydroxypropyl cellulose, hydroxypropyl methyl cellulose, hydroxyethyl methyl cellulose, hydroxypropyl methyl cellulose stearoxy ether, carboxymethyl hydroxyethyl cellulose, alkyl hydroxyethyl cellulose, and nonoxynyl hydroxyethyl cellulose.
  • the composition for secondary battery electrode mixture layer of the present invention is essentially composed of the binder, active material and water, and is obtained by mixing the components using known means.
  • the method of mixing the components is not particularly limited, and known methods can be used, but a method of dry blending powder components such as the active material, conductive assistant and binder, 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
  • a mixing means known mixers such as a planetary mixer, a thin film swirling mixer and a self-revolving mixer can be used, but it is preferable to use a thin film swirling mixer in order to obtain a good dispersion state in a short time.
  • a thin film swirling mixer it is preferable to perform preliminary dispersion in advance with a stirrer such as a disperser.
  • the pH of the above slurry is not particularly limited as long as the effects of the present invention are achieved, but it is preferably less than 12.5, and for example, when CMC is added, it is more preferable that it is less than 11.5 in terms of the small concern of hydrolysis, and even more preferable that it is less than 10.5.
  • the viscosity of the slurry is not particularly limited as long as it provides the effects of the present invention, but can be, for example, in the range of 100 to 30,000 mPa ⁇ s, or, for example, 500 to 20,000 mPa ⁇ s, or, for example, 1,000 to 10,000 mPa ⁇ s, as the B-type viscosity (25°C) at 20 rpm. If the viscosity of the slurry is within the above range, good coatability can be ensured.
  • the secondary battery electrode of the present invention comprises a mixture layer formed from the composition for secondary battery electrode mixture layer of the present invention on the surface of a current collector such as copper or aluminum.
  • the mixture layer is formed by applying the composition to the surface of the current collector and then drying and removing the medium such as water.
  • the method for applying the composition 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 drying can be performed by known methods such as hot air blowing, reduced pressure, (far) infrared radiation, and microwave irradiation.
  • the mixture layer obtained after drying is subjected to a compression treatment using a mold press, a roll press, or the like. Compression brings the active material and the binder into close contact with each other, and improves the strength of the mixture layer and its adhesion to the current collector.
  • the thickness of the mixture layer can be adjusted by compression to, for example, about 30 to 80% of the thickness before compression, and the thickness of the mixture layer after compression is generally about 4 to 200 ⁇ m.
  • Secondary Battery can be produced by providing the secondary battery electrode of the present invention with a separator and an electrolyte.
  • the electrolyte may be in a liquid or gel form.
  • the separator is disposed between the positive and negative electrodes of the battery, and serves to prevent short circuits caused by contact between the electrodes and to retain the electrolyte to ensure ionic conductivity.
  • the separator is preferably a film-like insulating microporous membrane having good ion permeability and mechanical strength.
  • Specific examples of the material that can be used include polyolefins such as polyethylene and polypropylene, and polytetrafluoroethylene.
  • the electrolyte may be a known one that is generally used depending on the type of active material.
  • specific solvents include cyclic carbonates with high dielectric constant and high electrolyte dissolving ability such as propylene carbonate and ethylene carbonate, and chain carbonates with low viscosity such as ethyl methyl carbonate, dimethyl carbonate and diethyl carbonate, which may be used alone or as a mixed solvent.
  • the electrolyte is used by dissolving lithium salts such as LiPF 6 , LiSbF 6 , LiBF 4 , LiClO 4 and LiAlO 4 in these solvents.
  • an aqueous potassium hydroxide solution may be used as the electrolyte.
  • the secondary battery is obtained by storing a positive electrode plate and a negative electrode plate separated by a separator in a spiral or stacked structure in a case or the like.
  • the content of structural units derived from each monomer in the carboxyl group-containing non-crosslinked polymer salt was measured by using a nuclear magnetic resonance (NMR) spectrometer.
  • NMR nuclear magnetic resonance
  • the carboxyl group-containing non-crosslinked polymer salt obtained in the Production Example and Comparative Production Example was spread on an aluminum cup and vacuum dried at 70°C for 2 hours to obtain a dried product.
  • the dried product was finely pulverized using a mortar and filled into a zirconia sleeve to obtain a measurement sample.
  • Solid-state NMR measurement was performed under the conditions described below to determine the content (mass%) of structural units derived from each monomer of the carboxyl group-containing non-crosslinked polymer salt.
  • the molecular weight of the carboxyl group-containing non-crosslinked polymer salt was measured by gel permeation chromatography (GPC). 0.1 g of each aqueous solution of the carboxyl group-containing non-crosslinked polymer salt obtained in the Production Example and Comparative Production Example (0.02 g as the solid content of the polymer salt) was collected and diluted with 40 g of 0.1 M sodium nitrate aqueous solution to obtain a measurement sample. The measurement sample was subjected to aqueous GPC measurement under the conditions described below to obtain the number average molecular weight (Mn) and weight average molecular weight (Mw) calculated in terms of sodium polyacrylate. The molecular weight distribution (Mw/Mn) was calculated from the obtained values.
  • V-50 2,2'-azobis(2-methylpropionamidine) dihydrochloride
  • LiOH.H 2 O lithium hydroxide monohydrate
  • AA acrylic acid
  • AAm acrylamide
  • AN acrylonitrile
  • V-50 2,2'-azobis(2-methylpropionamidine) dihydrochloride (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.)
  • LiOH.H2O Lithium hydroxide monohydrate
  • NaOH Sodium hydroxide
  • KOH Potassium hydroxide
  • Example 1 Preparation of electrode mixture layer composition
  • the active materials used were artificial graphite (manufactured by Showa Denko K.K., product name "SCMG-CF”) and SiO (5 ⁇ m, manufactured by Osaka Titanium Technologies Co., Ltd.)
  • the binder used was an aqueous solution of carboxyl group-containing non-crosslinked polymer salt R-1, a mixture of styrene/butadiene rubber (SBR) and sodium carboxymethyl cellulose (CMC).
  • SBR styrene/butadiene rubber
  • CMC sodium carboxymethyl cellulose
  • a planetary mixer Hibismix 2P-03 model, manufactured by Primix Corporation
  • the electrode slurry was applied onto a current collector (copper foil, thickness: 16.5 ⁇ m) using a variable applicator, and dried in a ventilated dryer at 80° C. for 15 minutes to form a mixture layer. After that, the mixture layer was rolled to a thickness of 50 ⁇ 5 ⁇ m and a mixture density of 1.60 ⁇ 0.10 g/cm 3, and then punched out into a 3 cm square to obtain a negative electrode plate for battery evaluation.
  • NMP N-methylpyrrolidone
  • 100 parts of LiNi0.5Co0.2Mn0.3O2 (NCM) as a positive electrode active material and 2 parts of acetylene black were mixed and added , and 4 parts of polyvinylidene fluoride (PVDF) as a positive electrode binder was mixed to prepare a composition for a positive electrode composite layer.
  • the positive electrode composite layer composition was applied to a current collector (aluminum foil, thickness: 20 ⁇ m) using a variable applicator and dried to form a composite layer.
  • the composite layer was rolled to a thickness of 125 ⁇ m ⁇ 1 ⁇ m and a composite density of 3.0 ⁇ 0.10 g/ cm3 , and then punched out into a 3 cm square to obtain a positive electrode plate for battery evaluation.
  • EC ethylene carbonate
  • DMC dimethyl carbonate
  • FEC fluoroethylene carbonate
  • the battery was constructed by attaching lead terminals to the positive and negative electrodes, and placing the electrodes facing each other through a separator (made of polyethylene: film thickness 16 ⁇ m, porosity 47%) in an aluminum laminate battery exterior, injecting the electrolyte, and sealing the battery to prepare a test battery.
  • the design capacity of this prototype battery was 50 mAh.
  • the design capacity of the battery was based on the charge cut-off voltage of 4.2 V.
  • C Charge/discharge capacity retention rate is 82.0% or more and less than 83.0%.
  • D Charge/discharge capacity retention rate is less than 82.0%.
  • Examples 2 to 17 and Comparative Examples 1 to 2 An electrode slurry was prepared in the same manner as in Example 1, except that the composition was as shown in Table 2. The cycle characteristics of a battery having a negative electrode plate obtained using the electrode slurry were evaluated. The results are shown in Table 2.
  • SBR Styrene butadiene rubber
  • CMC Sodium carboxymethyl cellulose
  • the cycle characteristics of the secondary battery were more excellent when Mn was 200,000 or less (Examples 3 to 6) compared with when Mn was more than 200,000 (Example 7). Furthermore, when focusing on Mw/Mn, the cycle characteristics of the secondary battery were more excellent when the Mw/Mn was in the wider range of 58.9 to 254 (Examples 3 and 4) compared to when it was in the range of 5.1 to 17.1 (Examples 5 to 7).
  • the neutralized salt of the carboxyl group-containing non-crosslinked polymer was a sodium salt (Comparative Example 1) or a potassium salt (Comparative Example 2)
  • the secondary battery had high DC resistance after the initial charge/discharge, resulting in poor cycle characteristics.
  • a secondary battery containing the binder for secondary battery electrodes of the present invention has low DC resistance after the first charge and discharge and exhibits good durability (cycle characteristics). Therefore, a secondary battery equipped with an electrode obtained using the binder is expected to ensure good integrity and exhibit good durability (cycle characteristics) even after repeated charge and discharge, and is expected to contribute to the development of high-capacity secondary batteries for vehicles, etc.
  • the binder for secondary battery electrodes of the present invention can be suitably used in particular for electrodes of non-aqueous electrolyte secondary batteries, and is particularly useful for non-aqueous electrolyte lithium ion secondary batteries having high energy density.

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Abstract

La présente invention concerne un liant pour électrodes de batterie secondaire, avec lequel il est possible de réduire la résistance interne d'une batterie secondaire et d'améliorer les caractéristiques de cycle de la batterie secondaire. La présente invention concerne également : une composition pour des couches de mélange d'électrode de batterie secondaire, ladite composition contenant le liant décrit ci-dessus ; une électrode négative de batterie secondaire qui est obtenue à l'aide de cette composition ; et une batterie secondaire.　La présente invention concerne spécifiquement un liant pour électrodes de batterie secondaire, le liant contenant un sel de lithium d'un polymère non réticulé contenant un groupe carboxyle. Le polymère non réticulé contenant un groupe carboxyle contient une unité structurale qui est dérivée d'un monomère d'acide carboxylique éthyléniquement insaturé, une unité structurale qui est dérivée d'un monomère éthyléniquement insaturé contenant un groupe amide, et une unité structurale qui est dérivée d'un monomère éthyléniquement insaturé contenant un groupe nitrile.
PCT/JP2024/026789 2023-08-09 2024-07-26 Liant pour électrodes de batterie secondaire et son utilisation Pending WO2025033218A1 (fr)

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Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2015186363A1 (fr) * 2014-06-04 2015-12-10 日本ゼオン株式会社 Composition de liant pour électrode de batterie rechargeable au lithium-ion, composition de boue pour électrode de batterie rechargeable au lithium-ion, électrode de batterie rechargeable au lithium-ion, et batterie rechargeable au lithium-ion
JP2018006334A (ja) * 2016-06-23 2018-01-11 荒川化学工業株式会社 リチウムイオン電池負極用スラリー及びその製造方法、リチウムイオン電池用負極、並びにリチウムイオン電池
JP2020205257A (ja) * 2019-06-17 2020-12-24 荒川化学工業株式会社 リチウムイオン電池用熱架橋性バインダー水溶液、リチウムイオン電池負極用熱架橋性スラリー、リチウムイオン電池用負極、リチウムイオン電池負極用材料、並びにリチウムイオン電池及びその製造方法
JP2021122751A (ja) * 2020-01-31 2021-08-30 東洋インキＳｃホールディングス株式会社 分散剤、導電材分散体、及び電極膜用スラリー
JP2021141057A (ja) * 2020-03-09 2021-09-16 荒川化学工業株式会社 リチウムイオン電池電極用バインダー水溶液、リチウムイオン電池負極用スラリー、リチウムイオン電池用負極及びリチウムイオン電池

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2015186363A1 (fr) * 2014-06-04 2015-12-10 日本ゼオン株式会社 Composition de liant pour électrode de batterie rechargeable au lithium-ion, composition de boue pour électrode de batterie rechargeable au lithium-ion, électrode de batterie rechargeable au lithium-ion, et batterie rechargeable au lithium-ion
JP2018006334A (ja) * 2016-06-23 2018-01-11 荒川化学工業株式会社 リチウムイオン電池負極用スラリー及びその製造方法、リチウムイオン電池用負極、並びにリチウムイオン電池
JP2020205257A (ja) * 2019-06-17 2020-12-24 荒川化学工業株式会社 リチウムイオン電池用熱架橋性バインダー水溶液、リチウムイオン電池負極用熱架橋性スラリー、リチウムイオン電池用負極、リチウムイオン電池負極用材料、並びにリチウムイオン電池及びその製造方法
JP2021122751A (ja) * 2020-01-31 2021-08-30 東洋インキＳｃホールディングス株式会社 分散剤、導電材分散体、及び電極膜用スラリー
JP2021141057A (ja) * 2020-03-09 2021-09-16 荒川化学工業株式会社 リチウムイオン電池電極用バインダー水溶液、リチウムイオン電池負極用スラリー、リチウムイオン電池用負極及びリチウムイオン電池

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