WO2023286793A1 - リチウムイオン電池電極用カーボンナノチューブ分散液 - Google Patents

リチウムイオン電池電極用カーボンナノチューブ分散液 Download PDF

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WO2023286793A1
WO2023286793A1 PCT/JP2022/027496 JP2022027496W WO2023286793A1 WO 2023286793 A1 WO2023286793 A1 WO 2023286793A1 JP 2022027496 W JP2022027496 W JP 2022027496W WO 2023286793 A1 WO2023286793 A1 WO 2023286793A1
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Prior art keywords
carbon nanotube
ion battery
lithium ion
nanotube dispersion
resin
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French (fr)
Japanese (ja)
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陽彦 沖山
有志 広瀬
慶一 片山
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Kansai Paint Co Ltd
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Kansai Paint Co Ltd
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Priority to JP2023507246A priority Critical patent/JP7459371B2/ja
Priority to CN202280049255.XA priority patent/CN117616602A/zh
Priority to US18/578,611 priority patent/US20240322181A1/en
Publication of WO2023286793A1 publication Critical patent/WO2023286793A1/ja
Anticipated expiration legal-status Critical
Priority to JP2024041747A priority patent/JP2024069513A/ja
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B32/00—Carbon; Compounds thereof
    • C01B32/15—Nano-sized carbon materials
    • C01B32/158—Carbon nanotubes
    • C01B32/168—After-treatment
    • C01B32/174—Derivatisation; Solubilisation; Dispersion in solvents
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B1/00—Conductors or conductive bodies characterised by the conductive materials; Selection of materials as conductors
    • H01B1/20—Conductive material dispersed in non-conductive organic material
    • H01B1/24—Conductive material dispersed in non-conductive organic material the conductive material comprising carbon-silicon compounds, carbon or silicon
    • 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
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • H01M4/621—Binders
    • H01M4/622—Binders being polymers
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • H01M4/624—Electric conductive fillers
    • H01M4/625—Carbon or graphite
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B2202/00—Structure or properties of carbon nanotubes
    • C01B2202/06—Multi-walled nanotubes
    • C—CHEMISTRY; METALLURGY
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    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B2202/00—Structure or properties of carbon nanotubes
    • C01B2202/20—Nanotubes characterized by their properties
    • C01B2202/24—Thermal properties
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    • C01B2202/00—Structure or properties of carbon nanotubes
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    • C01B2202/32—Specific surface area
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    • C01B2202/00—Structure or properties of carbon nanotubes
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    • C01B2202/34—Length
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    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B2202/00—Structure or properties of carbon nanotubes
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    • C01B2202/36—Diameter
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    • C01P2002/00—Crystal-structural characteristics
    • C01P2002/80—Crystal-structural characteristics defined by measured data other than those specified in group C01P2002/70
    • C01P2002/82—Crystal-structural characteristics defined by measured data other than those specified in group C01P2002/70 by IR- or Raman-data
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    • C01P2004/00—Particle morphology
    • C01P2004/10—Particle morphology extending in one dimension, e.g. needle-like
    • C01P2004/13—Nanotubes
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    • 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 carbon nanotube dispersions for lithium ion battery electrodes.
  • This application claims priority based on Japanese Patent Application No. 2021-115519 filed in Japan on July 13, 2021, the content of which is incorporated herein.
  • a lithium ion secondary battery is a type of secondary battery, and is a secondary battery in which lithium ions in an electrolyte are responsible for electrical conduction.
  • Lithium ion secondary batteries have excellent characteristics such as high energy density, excellent charge energy retention characteristics, and small so-called memory phenomenon in which the apparent capacity decreases. Therefore, lithium ion secondary batteries are used in a wide range of fields such as mobile phones, smart phones, personal computers, hybrid vehicles, and electric vehicles.
  • a lithium ion secondary battery mainly includes a positive electrode plate, a negative electrode plate, and the like. The positive electrode plate and the negative electrode plate are formed by forming an electrode layer (electrode mixture layer) on the surface of an electrode core material (also referred to as a current collector).
  • the electrode layer is produced by coating the surface of the electrode core material with a dispersion obtained by mixing an electrode active material with a carbon nanotube dispersion containing a conductive agent (carbon nanotube, etc.), a binder and a solvent, and drying it. be able to.
  • the electrode layer is produced by applying a carbon nanotube dispersion for a lithium ion battery electrode containing an electrode active material to the surface of the electrode core material. is required to have a low viscosity.
  • Patent Document 1 discloses an anionic surfactant (A), a nonionic surfactant (B), and an anionic surfactant (C) which is a compound different from the anionic surfactant (A).
  • Patent Document 2 discloses a carbon nanotube aqueous dispersion comprising (a) a polysaccharide, (b) a carbon nanotube, and (c) a water-soluble compound having a perfluoroalkyl group.
  • the dispersibility or storage stability of carbon nanotubes may be poor, and if a large amount of dispersant is added, the battery performance (internal resistance, capacity) is affected, so the amount of the dispersant is limited. . Therefore, there is a demand for a dispersant that can reduce the viscosity of the conductive paste in a small amount.
  • the problem to be solved by the present invention is to provide a carbon nanotube dispersion for lithium ion battery electrodes that has a viscosity that makes it easy to apply even if the amount of the dispersing resin is relatively small.
  • the present invention is based on such new findings. Accordingly, the present invention provides the following terms.
  • a carbon nanotube dispersion for lithium ion battery electrodes [1] A carbon nanotube dispersion containing a dispersion resin (A), carbon nanotubes (B), and water, wherein the dispersion resin (A) contains a polar functional group-containing resin (a)
  • a carbon nanotube dispersion for lithium ion battery electrodes A carbon nanotube dispersion for lithium ion battery electrodes.
  • the ionic polyvinyl alcohol resin (a1) is a sulfonic acid-modified polyvinyl alcohol resin (a1-1), and the monomer unit having a sulfonic acid group in the sulfonic acid-modified polyvinyl alcohol resin (a1-1)
  • Nanotube dispersion [5] The carbon nanotube dispersion for lithium ion battery electrodes according to [2], wherein the degree of saponification of the ionic polyvinyl alcohol resin (a1) is 50 to 100 mol%.
  • the BET specific surface area of the carbon nanotube (B) is 50 to 1800 m 2 /g, and the maximum peak intensity in the range of 1560 to 1600 cm ⁇ 1 in the Raman spectrum of the carbon nanotube (B) is G, 1310
  • the dispersion resin (A) is a carbon nanotube dispersion characterized in that it contains a polar functional group-containing resin (a),
  • a lithium ion battery electrode comprising the lithium ion battery electrode layer of [11] and a metal current collector.
  • Dispersing resin (A) blended in the carbon nanotube dispersion for lithium ion battery electrodes of the present invention is sufficient in a relatively small amount compared to the pigment dispersing resin conventionally used in carbon nanotube dispersions for lithium ion battery electrodes. It can reduce the viscosity of the paste and has good storage stability.
  • FIG. 3 is an explanatory diagram showing the correlation between the degree of structure growth of carbon nanotubes (B) and the Bode plot.
  • FIG. 3 is an explanatory diagram showing the correlation between the particle size distribution of aggregates of primary particles of carbon nanotubes (B) and the ratio of the minimum value (X) to the value (Y).
  • 1 is a cross-sectional view showing an example of a lithium ion battery electrode having a lithium ion battery electrode layer;
  • FIG. 1 is a cross-sectional view showing an example of a lithium ion battery;
  • FIG. 1 is a cross-sectional view showing an example of a lithium ion battery;
  • carbon nanotube dispersion for lithium ion battery electrode may be abbreviated as “carbon nanotube dispersion”
  • carbon nanotube may be abbreviated as “CNT”.
  • the present invention is a carbon nanotube dispersion containing a dispersing resin (A), carbon nanotubes (B), and water, wherein the dispersing resin (A) contains a polar functional group-containing resin (a). It is a carbon nanotube dispersion liquid for electrodes.
  • the "carbon nanotube dispersion" of the present application can also be rephrased as "aqueous carbon nanotube dispersion” because it always contains water as a solvent.
  • the dispersing resin (A) that can be used in the present invention contains a polar functional group-containing resin (a).
  • the polar functional group-containing resin (a) is a resin containing a highly polar functional group, and the polar functional group is an ionic and/or nonionic functional group.
  • Ionic functional groups include, for example, acidic functional groups such as sulfonic acid group, carboxyl group, sulfate group, phosphonic acid group, phosphoric acid group, phosphinic acid group, and mercapto group, primary, secondary and tertiary amino groups, ammonium groups, imino groups, and nitrogen-containing heterocyclic groups such as pyridine, pyrimidine, pyrazine, imidazole, and triazole.
  • nonionic functional groups include amide groups, polyoxyalkylene groups, and pyrrolidone groups.
  • the polar functional group-containing resin (a) is preferably an ionic polar functional group-containing resin (a), more preferably an ionic polyvinyl alcohol resin (a1) and/or carboxymethyl celluloses (a2), and carboxymethyl cellulose. Class (a2) is more preferred.
  • the ionic polyvinyl alcohol resin (a1) is a polyvinyl alcohol resin having the ionic functional group described above.
  • the ionic functional group preferably has an acidic functional group, more preferably has a sulfonic acid group or a carboxyl group, and particularly preferably has a sulfonic acid group.
  • the acidic functional group may be in the form of a free acid, or in the form of an alkali metal salt such as sodium salt or potassium salt, or an ammonium salt.
  • the ionic polyvinyl alcohol resin (a1) is preferably a sulfonic acid-modified polyvinyl alcohol resin (a1-1) and/or a carboxylic acid-modified polyvinyl alcohol resin (a1-2), and a sulfonic acid-modified polyvinyl alcohol resin (a1-1). is more preferred.
  • the sulfonic acid-modified polyvinyl alcohol resin (a1-1) can be produced, for example, by the following method. (1) A method of copolymerizing a compound containing a sulfonic acid group and a polymerizable unsaturated group with a fatty acid vinyl ester such as vinyl acetate and further saponifying the obtained polymer. (2) A method of Michael addition of vinylsulfonic acid, 2-acrylamido-2-methylpropanesulfonic acid or the like to polyvinyl alcohol.
  • the polymer obtained by copolymerizing the compound containing a sulfonic acid group and a polymerizable unsaturated group of (1) with a fatty acid vinyl ester such as vinyl acetate is Furthermore, the method of saponification is preferable.
  • the compound containing a sulfonic acid group and a polymerizable unsaturated group any compound that can be copolymerized with a fatty acid vinyl ester can be used without particular limitation. Specific examples include vinylsulfonic acid and isoprene.
  • Olefinsulfonic acids such as sulfonic acid, ethylenesulfonic acid, allylsulfonic acid, methallylsulfonic acid; sulfoalkylmalates such as sodium sulfopropyl 2-ethylhexyl maleate, sodium sulfopropyl tridecyl maleate, sodium sulfopropyl eicosyl maleate; 2-(meth)acrylamido-2-methylpropanesulfonic acid, sulfoalkyl(meth)acrylamides such as sodium N-sulfoisobutylene acrylamide; 3-methacryloyloxypropanesulfonic acid, 4-methacryloyloxybutanesulfonic acid, 3-methacryloyloxy- sulfoalkyl (meth)acrylates such as 2-hydroxypropanesulfonic acid, 3-acryloyloxypropanesulfonic acid, sulfoethyl (
  • the content of the polymerizable unsaturated monomer unit having a sulfonic acid group in the sulfonic acid-modified polyvinyl alcohol resin is preferably 0.1 to 30% by mass with respect to the total mass of the monomer units constituting the sulfonic acid-modified polyvinyl alcohol resin. , more preferably 0.2 to 10% by mass.
  • the "content ratio of monomer units having a sulfonic acid group in the resin (a1-1)” refers to the content ratio of the monomer having a sulfonic acid group in the monomer mixture that is the starting material for the resin (a1-1). means. Therefore, the content ratio of the monomer having a sulfonic acid group in the resin (a1-1) is 0.1 to 30% by mass with respect to the total mass of the monomer units constituting the resin (a1-1). means that the resin (a1-1) is a copolymer of raw material monomers containing 0.1 to 30% by mass of a monomer having a sulfonic acid group relative to the total weight of the raw material monomers.
  • the "content ratio of the monomer unit X in the resin Y” means the content ratio of the monomer X in the monomer mixture that is the raw material of the resin Y. Therefore, the content ratio of the polymerizable unsaturated group-containing monomer unit X in the resin Y is a% by mass with respect to the total mass of the monomer units constituting the resin Y means that the resin Y contains the raw material monomer. It means a copolymer of raw material monomers containing a mass % of monomer X with respect to the total mass. Moreover, when it hydrolyzes by saponification, it converts into the mass after saponification.
  • fatty acid vinyl esters to be copolymerized with compounds containing a sulfonic acid group and a polymerizable unsaturated group examples include vinyl formate, vinyl acetate, vinyl propionate, vinyl butyrate, vinyl caprate, vinyl caprylate, and vinyl caproate. , vinyl laurate, vinyl myristate, vinyl palmitate, vinyl stearate, vinyl pivalate, vinyl octylate, vinyl monochloroate, vinyl benzoate, vinyl cinnamate, vinyl crotonate, divinyl adipate, and derivatives thereof. These can be used singly or in combination of two or more. Among them, vinyl acetate is preferred.
  • copolymerizable polymerizable unsaturated monomers include, for example, olefinic monomers such as ethylene and propylene; Acryloyl group-containing monomers; allyl ethers such as allyl glycidyl ether; vinyl halide compounds such as vinyl chloride, vinylidene chloride and vinyl fluoride; vinyl ethers such as alkyl vinyl ethers and 4-hydroxyvinyl ethers. These can be used individually by 1 type or in combination of 2 or more types.
  • the degree of polymerization of the sulfonic acid-modified polyvinyl alcohol resin (a1-1) is preferably from 100 to 4,000, more preferably from 100 to 3,000.
  • the degree of polymerization can be calculated based on the molecular weight of the resin.
  • the retention time (retention volume) measured using gel permeation chromatography (GPC) is converted to the molecular weight of polystyrene by the retention time (retention volume) of standard polystyrene with a known molecular weight measured under the same conditions.
  • HLC8120GPC (trade name, manufactured by Tosoh Corporation) is used as a gel permeation chromatograph, and "TSKgel G-4000HXL”, “TSKgel G-3000HXL”, and “TSKgel G-2500HXL” are used as columns. ” and “TSKgel G-2000HXL” (trade name, both manufactured by Tosoh Corporation), mobile phase tetrahydrofuran, measurement temperature 40 ° C., flow rate 1 mL / min and detector RI. can.
  • the saponification degree of the sulfonic acid-modified polyvinyl alcohol resin (a1-1) is preferably in the range of 60 to 100 mol%, more preferably in the range of 70 to 100 mol%, and 80 to 100 mol%. It is more preferably within the range, and particularly preferably within the range of 90 to 99.9 mol %.
  • the degree of saponification can be measured by a measuring method conforming to JIS K6726-1994, or by a measuring method modified according to the resin composition based on the measuring method.
  • a low degree of saponification results in poor solubility in aqueous solvents.
  • the reason why the ionic polyvinyl alcohol resin (sulfonic acid-modified polyvinyl alcohol resin, carboxylic acid-modified polyvinyl alcohol resin, etc.) has an effect on the dispersibility and storage stability of the carbon nanotube dispersion is that moderate polarity
  • a specific ionic functional group to the side chain of the resin while ensuring solubility in an aqueous solvent by the main chain of the resin having It is considered that both the solubility and the adsorptivity to the pigment were achieved.
  • the resin (a1-1) can be produced by a polymerization method known per se, for example, a method of solution polymerization in an organic solvent, but is not limited to this, for example, bulk polymerization. Alternatively, emulsion polymerization, suspension polymerization, or the like may be used. When solution polymerization is carried out, it may be continuous polymerization or batch polymerization.
  • the polymerization initiator used in the solution polymerization is not particularly limited, but specific examples include azobisisobutyronitrile, azobis-2,4-dimethylpareronitrile, azobis(4-methoxy-2 ,4-dimethylpareronitrile) and other azo compounds; acetyl peroxide, benzoyl peroxide, lauroyl peroxide, acetylcyclohexylsulfonyl peroxide, 2,4,4-trimethylpentyl-2-peroxyphenoxyacetate and other peroxides
  • Peroxydicarbonate compounds such as diisopropyl peroxydicarbonate, di-2-ethylhexyl peroxydicarbonate, diethoxyethyl peroxydicarbonate; t-butyl peroxyneodecanate, cumyl peroxyneodecanate, t -Perester compounds such as butyl peroxyneodecanate; known
  • the polymerization reaction temperature is not particularly limited, it can usually be set in the range of about 30 to 200°C.
  • Conditions for saponification are not particularly limited, and saponification can be performed by a known method. For example, it can be carried out by hydrolyzing the ester moiety in the molecule in an alcohol solution such as methanol in the presence of an alkali catalyst or an acid catalyst.
  • alkali catalysts that can be used include hydroxides of alkali metals such as sodium hydroxide, potassium hydroxide, sodium methylate, sodium ethylate and potassium methylate, and alcoholates.
  • acid catalysts that can be used include aqueous solutions of inorganic acids such as hydrochloric acid and sulfuric acid, and organic acids such as p-toluenesulfonic acid, but it is desirable to use sodium hydroxide.
  • the saponification reaction temperature is not particularly limited, but is preferably in the range of 10 to 70°C, more preferably in the range of 30 to 40°C.
  • the reaction time is not particularly limited, it is desirable to carry out the reaction within the range of 30 minutes to 3 hours.
  • the above resin (a1-1) can be made into a solid or a resin solution in which an arbitrary solvent is substituted by removing the solvent and/or replacing the solvent after the completion of the synthesis.
  • removing the solvent heating may be performed at normal pressure, or the solvent may be removed under reduced pressure.
  • solvent replacement the replacement solvent may be added at any stage before, during, or after solvent removal.
  • the carboxylic acid-modified polyvinyl alcohol resin (a1-2) preferably contains a carboxyl group and has a saponification degree of 60 to 100 mol%, more preferably 70 to 100 mol%. It is preferably within the range of 80 to 100 mol %, and particularly preferably within the range of 90 to 99.9 mol %.
  • the degree of polymerization of the carboxylic acid-modified polyvinyl alcohol resin (a1-2) is preferably 100 to 4,000, more preferably 100 to 3,000.
  • the carboxylic acid-modified polyvinyl alcohol resin (a1-2) is produced by a polymerization method known per se, for example, by copolymerizing a compound containing a carboxyl group and a polymerizable unsaturated group with a fatty acid vinyl ester such as vinyl acetate, It can be obtained by a method of further saponifying the resulting polymer. Also, a carboxyl group can be introduced (contained) by modifying the polyvinyl alcohol resin after it is synthesized.
  • the content of the polymerizable unsaturated monomer unit having a carboxyl group is preferably 0.1 to 30% by mass, more preferably 0.1 to 30% by mass, based on the total mass of the monomer units constituting the carboxylic acid-modified polyvinyl alcohol resin (a1-2). is 0.2 to 10% by mass, more preferably 0.2 to 5% by mass.
  • the method described for the resin (a1-1) can be suitably used.
  • Polyvinyl alcohol resin (a1-3) containing other ionic functional groups As the ionic polyvinyl alcohol resin (a1), in addition to the above-described sulfonic acid-modified polyvinyl alcohol resin (a1-1) and carboxylic acid-modified polyvinyl alcohol resin (a1-2), ionic groups other than sulfonic acid groups and carboxyl groups A polyvinyl alcohol resin (a1-3) containing functional groups can be used. As for the ionic functional groups other than the sulfonic acid group and the carboxyl group, the above-mentioned acidic functional groups and basic functional groups can be preferably used, and among them, the acidic functional groups are preferable.
  • the resin (a1-3) preferably contains no sulfonic acid group or carboxyl group and has a degree of saponification of 60 to 100 mol%, more preferably 70 to 100 mol%. , more preferably in the range of 80 to 100 mol %, particularly preferably in the range of 90 to 99.9 mol %.
  • the degree of polymerization of the polyvinyl alcohol resin (a1-3) containing an ionic functional group other than a sulfonic acid group and a carboxyl group is preferably 100 to 4,000, more preferably 100 to 3,000. .
  • the polyvinyl alcohol resin (a1-3) containing an ionic functional group other than the sulfonic acid group and the carboxyl group is polymerized by a known polymerization method, for example, an ionic functional group other than the sulfonic acid group and the carboxyl group and a polymerizable It can be obtained by copolymerizing a compound containing a saturated group and a fatty acid vinyl ester such as vinyl acetate, and further saponifying the obtained polymer.
  • the content of polymerizable unsaturated monomer units having an ionic functional group other than a sulfonic acid group and a carboxyl group is 0.1 to 30 with respect to the total mass of monomer units constituting the polyvinyl alcohol resin (a1-3). % by mass is preferred, more preferably 0.2 to 10% by mass, and even more preferably 0.2 to 5% by mass.
  • the method described for the resin (a1-1) can be suitably used.
  • carboxymethylcellulose (a2) is a compound having a structure in which some or all of the hydroxyl groups in glucose residues constituting cellulose are substituted with carboxymethyl ether groups, and may be in the form of a salt.
  • carboxymethylcellulose salts include metal salts such as carboxymethylcellulose sodium salt.
  • the weight average molecular weight of the carboxymethylcelluloses is preferably 5,000 to 500,000, more preferably 10,000 to 100,000.
  • the weight average molecular weight can be measured by the molecular weight measurement method using gel permeation chromatography (GPC) described in the above-mentioned "Method for measuring degree of polymerization”.
  • the degree of etherification of the carboxymethylcelluloses is preferably 0.5 to 1.5, more preferably 0.6 to 1.2.
  • the degree of etherification is measured using an ashing measurement method. Specifically, 0.6 g of carboxymethyl cellulose is dried at 105° C. for 4 hours. After accurately weighing the mass of the dried product, it is wrapped in filter paper and incinerated in a porcelain crucible. Transfer the ash to a 500 mL beaker, add 250 mL of water and 35 mL of 0.05 mol/L sulfuric acid aqueous solution, and boil for 30 minutes. After cooling, excess acid is back-titrated with 0.1 mol/L potassium hydroxide aqueous solution.
  • Phenolphthalein is used as an indicator.
  • degree of etherification 162 x A/(10000-80A)
  • A (af-bf1) / mass of dry matter (g)
  • the method for producing the carboxymethyl cellulose is not particularly limited, and it can be produced by a production method known per se.
  • it can be produced by reacting cellulose with an alkali, adding an etherification agent to the alkali-modified cellulose, and performing an etherification reaction.
  • the dispersing resin (A) may optionally contain a resin other than the above resin (a).
  • a resin other than the above resin (a) examples include acrylic resins other than the resin (a), polyester resins, epoxy resins, alkyd resins, urethane resins, silicone resins, polycarbonate resins, chlorine resins, fluorine resins, polyvinyl acetal resins, composite resins thereof, and the like. .
  • These resins can be used singly or in combination of two or more. Among them, it is preferable to use at least one polyvinylidene fluoride (PVDF). Further, these resins can be blended into the carbon nanotube dispersion liquid as pigment dispersion resins or as additive resins after pigment dispersion.
  • PVDF polyvinylidene fluoride
  • Single-walled carbon nanotubes or multi-walled carbon nanotubes can be used alone or in combination as the carbon nanotubes (B).
  • the average outer diameter of the carbon nanotubes (B) is preferably 0.5 to 30 nm, more preferably 0.7 to 20 nm, and particularly preferably 1 to 10 nm.
  • the average value of the outer diameter of the carbon nanotubes (B) is obtained by observing 100 arbitrarily extracted carbon nanotubes with a transmission electron microscope, measuring the outer diameter of each, and calculating the average value. It is a value obtained by asking.
  • the average length of the carbon nanotubes (B) is preferably 1 to 100 ⁇ m, more preferably 5 to 80 ⁇ m, particularly preferably 10 to 60 ⁇ m.
  • the average value of the length of the carbon nanotubes (B) is obtained by observing 100 arbitrarily extracted carbon nanotubes with a transmission electron microscope, measuring the length of each, and calculating the average value. It is a value obtained by asking.
  • the average particle diameter (D50) of aggregates of primary particles of carbon nanotubes (B) is preferably less than 7 ⁇ m, more preferably 5 ⁇ m or less, and particularly preferably less than 4 ⁇ m.
  • the average particle diameter (D50) is obtained by diluting and stirring a carbon nanotube dispersion with water to a measurement concentration, and using a particle size distribution measuring device (manufactured by Microtrack Bell, Inc.) using a laser diffraction scattering method.
  • Product name: Microtrac MT3000 is a value calculated by volume-based particle size distribution measurement.
  • the BET specific surface area of the carbon nanotubes (B) is preferably in the range of 50 to 1800 m 2 /g, more preferably in the range of 600 to 1600 m 2 /g, in terms of viscosity and conductivity. It is preferably in the range of 800 to 1400 m 2 /g, more preferably.
  • the BET specific surface area is a value obtained by a measurement method based on "JIS Z8830 Method for measuring specific surface area of powder (solid) by gas adsorption".
  • Single-walled carbon nanotubes generally have a large specific surface area, while multi-walled carbon nanotubes have a small specific surface area. Therefore, single-walled carbon nanotubes with a large specific surface area are suitable for electrode applications.
  • G is the maximum peak intensity within the range of 1560 to 1600 cm -1
  • D is the maximum peak intensity within the range of 1310 to 1350 cm -1 .
  • the D ratio is usually 5 to 200, preferably 20 to 180, more preferably 40 to 150, even more preferably 70 to 130.
  • the Raman spectrum of a carbon nanotube is a value obtained by placing the carbon nanotube in a Raman microscope (XploRA, manufactured by Horiba, Ltd.) and using a laser wavelength of 532 nm.
  • G / D ratio among the obtained peaks, the maximum peak intensity within the range of 1560 ⁇ 1600 cm -1 in the spectrum G, the maximum peak intensity within the range of 1310 ⁇ 1350 cm -1 as D G / It is a value calculated as the ratio of D as the G/D ratio of the carbon nanotube.
  • the carbon nanotube (B) is preferably one type of carbon nanotube.
  • the carbon nanotube dispersion of the present invention may contain conductive pigments other than carbon nanotubes.
  • conductive carbon (B-2) such as acetylene black, ketjen black, furnace black, thermal black, graphene, and graphite. These conductive carbons (B-2) can also be used in combination of two or more.
  • the average primary particle size of the conductive carbon (B-2) is preferably in the range of 10 to 80 nm, more preferably in the range of 20 to 50 nm, in view of the relationship between viscosity and conductivity.
  • the average primary particle size is defined by observing the pigment with an electron microscope, determining the projected area of each of 100 particles, and determining the diameter when a circle equal to the area is assumed. means the average diameter of primary particles obtained by simply averaging the diameters of
  • the primary particles constituting the aggregated particles are used in the calculation.
  • the BET specific surface area of the conductive carbon (B-2) is preferably in the range of 1 to 500 m 2 /g, more preferably in the range of 30 to 150 m 2 /g, in view of the relationship between viscosity and conductivity. is more preferred.
  • the above-mentioned conductive carbon (B-2) is preferably basic in terms of pigment dispersibility. is more preferred, and 8.5 to 11.0 is even more preferred.
  • the pH of conductive carbon (B-2) can be measured according to ASTM D1512.
  • the conductive carbon (B-2) preferably has a state in which the primary particles form a chain structure (structure), and the structure index is in the range of 1.5 to 4.0. more preferably within the range of 1.7 to 3.2.
  • the structure itself can be observed relatively easily in an image taken with an electron microscope, but the structure index is a numerical value that quantifies the degree of structure.
  • the structure index can generally be defined as a value obtained by dividing the DBP oil absorption (ml/100g) by the specific surface area (m 2 /g). When the structure index is 1.5 or more, the structure develops and sufficient conductivity can be easily obtained.
  • the particle diameter becomes a moderate size with respect to the DBP oil absorption, and it becomes easy to secure a conductive path, so that sufficient conductivity can be exhibited and the carbon nanotube It becomes easy to make the viscosity of the dispersion liquid moderate.
  • the carbon nanotube dispersion of the present invention contains water as a solvent, but may contain a solvent other than water (especially an aqueous solvent that dissolves in water).
  • a solvent especially an aqueous solvent that dissolves in water.
  • the aqueous solvent include alcohols such as ethanol, propanol, butanol, methyl cellosolve, butyl cellosolve, propylene glycol monomethyl ether, and N-methyl-2-pyrrolidone. These solvents can be used alone or in combination of two or more together with water.
  • the carbon nanotube dispersion of the present invention may contain components other than the components (A), (B) and water (also referred to as other additives).
  • Other additives include, for example, neutralizers, pH adjusters, pigment dispersants, antifoaming agents, antiseptics, rust inhibitors, plasticizers, binders, and the like.
  • the initial viscosity of the carbon nanotube dispersion liquid is preferably less than 15 Pa ⁇ s, more preferably 13 Pa ⁇ s or less, and particularly preferably less than 12 Pa ⁇ s.
  • the initial viscosity of the carbon nanotube dispersion is measured by measuring the carbon nanotube dispersion with a cone & plate viscometer (manufactured by HAAKE, trade name: Mars2, diameter 35 mm, cone & plate inclined at 2°). , and measured at a shear rate of 5.0 sec -1 .
  • the carbon nanotube dispersion liquid used for the measurement is used within 60 minutes from immediately after the production of the carbon nanotube dispersion liquid.
  • the volume resistivity of the lithium-ion battery electrode layer formed from the carbon nanotube dispersion is preferably less than 12 ⁇ cm, more preferably less than 10 ⁇ cm, and particularly preferably 9 ⁇ cm or less. preferable.
  • the volume resistivity of the electrode layer for a lithium ion battery is determined by measuring the film thickness of the electrode layer and then using an ASP probe (manufactured by Mitsubishi Chemical Analytic Tech Co., Ltd., trade name "MCP-TP03P").
  • the resistance value is measured with a resistivity meter (manufactured by Mitsubishi Chemical Analytech Co., Ltd., trade name “Loresta-GP MCP-T610”), and the obtained resistance value is added with a resistivity correction factor (RCF) of 4.532 and It is a value obtained by multiplying the film thickness to calculate the volume resistivity.
  • RCF resistivity correction factor
  • the lithium ion battery electrode of the present invention is obtained by applying the carbon nanotube dispersion of the present invention to a metal current collector to form a lithium ion battery electrode layer.
  • FIG. 3 is a cross-sectional view showing an example of a lithium ion battery electrode having a lithium ion battery electrode layer.
  • the carbon nanotube dispersion of the present invention is applied to a metal current collector 101 to form a lithium ion battery electrode layer 102 to form a lithium ion battery electrode 100 .
  • the lithium ion battery of the present invention has the lithium ion battery electrode layer of the present invention only on the positive electrode, only on the negative electrode, or on both the positive electrode and the negative electrode.
  • FIG. 4 is a cross-sectional view showing an example of a lithium ion battery.
  • metal current collector (negative electrode) 101b, lithium ion battery electrode layer (negative electrode) 102b, separator 103, lithium ion battery electrode layer (positive electrode) 102a, and metal current collector (positive electrode) 101a are shown in this order. They are stacked to form a lithium-ion battery.
  • the metal current collector (negative electrode) 101b and the lithium ion battery electrode layer (negative electrode) 102b constitute the lithium ion battery negative electrode 100b, and the metal current collector (positive electrode) 101a and the lithium ion battery electrode layer ( The positive electrode) 102a constitutes a positive electrode 100a for a lithium ion battery.
  • At least one of the lithium ion battery electrode layer (negative electrode) 102b and the lithium ion battery electrode layer (positive electrode) 102a may be formed from the carbon nanotube dispersion of the present invention, and the other is the carbon nanotube of the present invention. It does not have to be formed from a dispersion.
  • the separator 103 holds an electrolyte (not shown).
  • the solid content in the carbon nanotube dispersion (also simply referred to as "carbon nanotube dispersion") which is the first aspect of the present invention is usually less than 50% by mass with respect to the total mass of the carbon nanotube dispersion. It is preferably 10% by mass or less, and particularly preferably 5% by mass or less.
  • the carbon nanotube dispersion of the first aspect of the present invention does not contain an electrode active material, and the carbon nanotube dispersion for a lithium ion battery electrode of the second aspect of the present invention, which will be described later, does not contain an electrode active material. includes.
  • the total amount of the solid content of the dispersion resin (A) in the solid content of the carbon nanotube dispersion of the present invention is usually preferably 70% by mass or less with respect to the total mass of the solid content of the carbon nanotube dispersion, and more
  • the content is preferably 60% by mass or less, more preferably 50% by mass or less, from the viewpoints of viscosity, pigment dispersibility, dispersion stability, production efficiency, etc. during pigment dispersion.
  • the content of the dispersing resin (A) in the carbon nanotube dispersion of the present invention is generally preferably 0.2% by mass or more and 10% by mass or less with respect to the total mass of the carbon nanotube dispersion.
  • the solid content of the carbon nanotubes (B) in the solid content of the carbon nanotube dispersion of the present invention is usually preferably 30% by mass or more and less than 85% by mass based on the total mass of the solid content of the carbon nanotube dispersion. From the viewpoint of battery performance, the content is preferably 40% by mass or more and less than 80% by mass, and more preferably 50% by mass or more and less than 75% by mass.
  • the content of the carbon nanotubes (B) in the carbon nanotube dispersion of the present invention is generally preferably 0.2% by mass or more and 5% by mass or less with respect to the total mass of the carbon nanotube dispersion. It is more preferably 3% by mass or more and 3% by mass or less, and particularly preferably 0.5% by mass or more and 1.5% by mass or less.
  • the content of the solvent in the carbon nanotube dispersion of the present invention is usually preferably 50% by mass or more and less than 100% by mass, more preferably 70% by mass, relative to the total mass of the carbon nanotube dispersion. Above and below 99% by mass, more preferably above 80% by mass and below 98.5% by mass, is suitable from the viewpoint of drying efficiency and paste viscosity.
  • the total content of each component contained in the carbon nanotube dispersion of the present invention does not exceed 100% by mass with respect to the total mass of the carbon nanotube dispersion.
  • the carbon nanotube dispersion of the present invention can be prepared by using each component described above, for example, scandics, paint shaker, sand mill, ball mill, pebble mill, LMZ mill, DCP pearl mill, planetary ball mill, homogenizer, twin-screw kneader, thin film swirl type It can be prepared by uniformly mixing and dispersing using a conventionally known dispersing machine such as a high-speed mixer.
  • the carbon nanotube dispersion of the present invention is obtained by mixing a dispersion resin (A), carbon nanotubes (B), and water, and using a dispersing machine (M Technic Co., Clearmix CLM-2.2S). Disperse until the whole is uniform at a speed of 14,000 rpm and the dispersed particle size (D50) is 90 ⁇ m or less, and then disperse 12 passes at 60 MPa using a high pressure homogenizer (manufactured by Yoshida Kikai Co., Ltd., NanoVita). After that, it is preferable to carry out dispersion under specific dispersion conditions (the number of passes).
  • the number of passes is preferably more than 5 and less than 70, more preferably 7.5 or more and 50 or less, and particularly preferably 8 or more and 45 or less.
  • the carbon nanotube dispersion of the present invention can be mixed with an electrode active material and used to produce an electrode layer for a lithium ion battery electrode.
  • the absorbance (wavelength: 268 nm) of the carbon nanotube dispersion is preferably 1.3 or more, more preferably 1.3 to 2.0, and particularly preferably 1.3 to 1.8. .
  • the absorbance is 1.3 or more, the dispersibility is moderately advanced, and when it is 2.0 or less, it becomes easy to prevent excessive dispersion.
  • the absorbance of the carbon nanotube dispersion is measured by diluting the carbon nanotube dispersion with deionized water to prepare a CNT concentration of 0.001% by mass, stirring until uniform, and then filling the sample into the cell. Then, U-1900 (trade name, spectrophotometer, manufactured by Hitachi High-Technologies Corporation) was used to measure the absorbance at a wavelength (268 nm).
  • the carbon nanotube dispersion which is the first aspect of the present invention, has a minimum value of reactance in the frequency range of 170 to 600 kHz in a Bode plot obtained by impedance measurement, in which reactance is plotted on the vertical axis and frequency is plotted on the horizontal axis. characterized by existence.
  • the minimum value of reactance preferably exists in the frequency range of 180-600 kHz, more preferably in the frequency range of 200-400 kHz.
  • reactance means the imaginary part of complex impedance.
  • the Bode plot uses a bipolar electrode with a distance between the electrodes of 9 mm in which copper plates with a thickness of 0.3 mm with a gold-plated surface are opposed, and the size of the electrode is 100 mm 2 .
  • a 20-ml cylindrical container is filled with 15 ml of the carbon nanotube dispersion, and the electrode is inserted so that it is completely immersed in the paste.
  • a sinusoidal AC voltage with a peak-to-peak voltage of 0.1 V was applied to the carbon nanotube dispersion at 25 ° C. using an impedance analyzer (manufactured by Keysight, trade name “4294A”), and the frequency was 100 Hz to 100 MHz.
  • the complex impedance and phase difference are measured at 500 points while sweeping between . From the obtained data, it is obtained by plotting the reactance on the vertical axis and the frequency on the horizontal axis.
  • the ratio (ratio) of the minimum value of reactance to the reactance at a frequency of 1 kHz is preferably more than 1.5 and 5.0 or less, and is 1.6 or more and 4.0 or less. More preferably, it is particularly preferably 1.7 or more and 3.5 or less.
  • Multiplier (ratio) of the minimum value of reactance to the reactance at a frequency of 1 kHz [minimum value of reactance] ⁇ [reactance at a frequency of 1 kHz]
  • the carbon nanotube (B) forms a structure in the carbon nanotube dispersion liquid, but the minimum value of the reactance in the Bode plot indicates the degree of growth of the structure of the carbon nanotube (B), that is, the primary particles of the carbon nanotube (B). migrates depending on the size of the aggregates. For example, as shown in FIG. 1, the stronger the interaction of the primary particles 10 and the higher the degree of structure growth, that is, the larger the aggregate of the primary particles of the carbon nanotubes (B), the more the minimum value of the reactance in the Bode plot. tend to be more likely to move to the low frequency region.
  • (a) is a Bode plot when the degree of structure growth is high
  • (b) is a Bode plot when the degree of structure growth is moderate
  • (c) is a Bode plot when the degree of structure growth is low.
  • the Bode plot if there is a minimum value of reactance in the frequency range of 170 to 600 kHz, the structure of the carbon nanotube (B) is growing moderately, that is, the carbon nanotube (B) in the carbon nanotube dispersion liquid It means that the primary particles of are dispersed while maintaining a proper structure. Therefore, when an electrode layer is formed using the carbon nanotube dispersion of the present invention, the primary particles of the carbon nanotube (B) are dispersed in the electrode layer while maintaining a proper structure.
  • a Bode plot can be obtained, for example, from the impedance measurement shown below.
  • the minimum value (X) of the reactance present in the frequency range of 170 to 600 kHz is preferably 1.8 times or more, and 2.0 times or more, the reactance value (Y) at a frequency of 1 kHz. more preferably 2.0 to 3.5 times, particularly preferably 2.3 to 3.2 times.
  • the Bode plot may have two or more local minimum values of reactance. Even if there are a plurality of minimum values in the range of 170-600 kHz, the calculation (X/Y) should be performed with the minimum value in the range of 170-600 kHz.
  • the ratio of the minimum value (X) to the value (Y) is affected by the particle size distribution of aggregates of primary particles of carbon nanotubes (B). For example, as shown in (a) in FIG. 2, the more uniform the particle diameter of the aggregates of the primary particles of the carbon nanotube (B), that is, the more uniform the minimum value (X ) tends to increase. On the other hand, as shown in FIG. 2(b), as the particle size of the aggregates 30 of the primary particles 10 of the carbon nanotubes (B) becomes more non-uniform, the ratio of the minimum value (X) to the value (Y) increases. tends to be smaller.
  • the minimum value (X) is 1.8 times or more the value (Y), it means that the particle size of aggregates of primary particles of carbon nanotubes (B) in the carbon nanotube dispersion is uniform. . Therefore, when an electrode layer is formed using the carbon nanotube dispersion for lithium ion battery electrodes containing the electrode active material of the present invention, the primary particles of the carbon nanotubes (B) are more uniformly dispersed in the electrode layer. Therefore, a conductive path is formed more efficiently, and an electrode layer having better conductivity can be formed.
  • a carbon nanotube dispersion for a lithium ion battery electrode (simply Also referred to as “a carbon nanotube dispersion for lithium ion battery electrodes”).
  • the “coating film obtained by applying the carbon nanotube dispersion” may be referred to as "electrode layer”.
  • Electrode active material As the electrode active material, those known per se can be suitably used.
  • positive electrode active materials include lithium nickelate (LiNiO 2 ), lithium manganate (LiMn 2 O 4 ), lithium cobaltate (LiCoO 2 ), LiNi 1/3 Co 1/3 Mn 1/3 O 2 and lithium composite oxides such as These electrode active materials can be used individually by 1 type or in mixture of 2 or more types.
  • negative electrode active materials include Li-based compounds, Sn-based compounds, Si-based compounds, graphite (natural graphite, artificial graphite), low-crystalline carbon (hard carbon, soft carbon), and the like. These electrode active materials can be used individually by 1 type or in mixture of 2 or more types.
  • the solid content in the carbon nanotube dispersion for lithium ion battery electrodes of the present invention is usually 70% by mass or more and less than 100% by mass with respect to the total mass of the carbon nanotube dispersion for lithium ion battery electrodes. , more preferably 80% by mass or more and less than 99% by mass, and particularly preferably 90% by mass or more and less than 98% by mass.
  • the solid content of the electrode active material in the solid content of the carbon nanotube dispersion for lithium ion battery electrodes of the present invention containing the electrode active material is usually 90% by mass or more and less than 100% by mass, preferably 95% by mass or more and less than 100% by mass, more preferably 98% by mass or more and less than 100% by mass, in terms of battery capacity, battery resistance, etc.
  • the content of the electrode active material in the carbon nanotube dispersion for lithium ion battery electrodes of the present invention is usually 30% by mass or more and less than 100% by mass with respect to the total mass of the carbon nanotube dispersion for lithium ion battery electrodes. It is preferably 40% by mass or more and less than 99% by mass, and particularly preferably 50% by mass or more and less than 98% by mass.
  • the carbon nanotube dispersion for a lithium ion battery electrode of the present invention is prepared by first preparing the carbon nanotube dispersion that is the first aspect of the present invention containing the above-described component (A), component (B), and water, and It can be obtained by blending an electrode active material with a nanotube dispersion.
  • the carbon nanotube dispersion liquid for lithium ion battery electrodes of the present invention may be prepared by simultaneously mixing the aforementioned component (A), component (B), water, and an electrode active material.
  • the total amount of the solid content of the dispersion resin (A) in the carbon nanotube dispersion solids for lithium ion battery electrodes containing the electrode active material of the present invention is usually the carbon nanotube dispersion solids for lithium ion battery electrodes 0.001 to 20% by mass, preferably 0.005 to 10% by mass, based on the total mass of the battery performance, paste viscosity and the like.
  • the solid content of the carbon nanotubes (B) in the solid content of the carbon nanotube dispersion for lithium ion battery electrodes containing the electrode active material of the present invention is usually the total solid content of the carbon nanotube dispersion for lithium ion battery electrodes. 0.01 to 30% by mass, preferably 0.05 to 20% by mass, more preferably 0.1 to 15% by mass based on the mass is suitable from the viewpoint of battery performance.
  • the content of the solvent in the carbon nanotube dispersion for lithium ion battery electrodes containing the electrode active material of the present invention is usually 0.1 to 60 with respect to the total mass of the carbon nanotube dispersion for lithium ion battery electrodes. % by mass, preferably 0.5 to 50% by mass, more preferably 1 to 45% by mass, from the viewpoint of electrode drying efficiency and paste viscosity.
  • the electrode of a lithium ion secondary battery is obtained by applying a carbon nanotube dispersion for a lithium ion battery electrode containing an electrode active material to the surface of an electrode core material (metal current collector) and drying it.
  • a carbon nanotube dispersion liquid for lithium ion battery electrode of the present invention it can be used as a primer layer between the electrode core material and the electrode layer.
  • the method of applying the carbon nanotube dispersion containing the electrode active material for lithium ion battery electrodes can be carried out by a method known per se using a die coater or the like.
  • the coating amount of the carbon nanotube dispersion for lithium ion battery electrodes containing the electrode active material is not particularly limited. 0.4 mm range).
  • the temperature of the drying process can be appropriately set, for example, within the range of 80 to 200°C, preferably 100 to 180°C.
  • the time for the drying process can be appropriately set within a range of, for example, 5 to 1200 seconds, preferably 5 to 120 seconds.
  • the lithium ion battery of the present invention uses the electrode of the lithium ion secondary battery of the present invention as only the positive electrode, only the negative electrode, or both the positive electrode and the negative electrode, and a separator is laminated between the positive electrode and the negative electrode. and then injecting the electrolyte into the resulting laminate.
  • Parts in each example means parts by mass
  • % means % by mass
  • Production Example 2 Production of Sulfonic Acid-Modified Polyvinyl Alcohol Resin 92 parts by mass of vinyl acetate and 2.0 parts by mass of sodium allylsulfonate as polymerizable monomers were placed in a reaction vessel equipped with a thermometer, a reflux condenser, a nitrogen gas inlet tube and a stirrer. Part, methanol as a solvent, and azobisisobutyronitrile as a polymerization initiator, a copolymerization reaction was carried out at a temperature of about 60° C., and then unreacted monomers were removed under reduced pressure to obtain a resin solution. Next, a solution of sodium hydroxide in methanol was added to cause a saponification reaction, which was thoroughly washed and then dried with a hot air dryer. Finally, polyvinyl alcohol resin no. 2 (PVA2) was obtained.
  • PVA2 polyvinyl alcohol resin no. 2
  • Production Example 3 Production of carboxylic acid-modified polyvinyl alcohol resin Into a reaction vessel equipped with a thermometer, a reflux condenser, a nitrogen gas inlet tube and a stirrer, 92 parts by mass of vinyl acetate as polymerizable monomers and 2.0 parts by mass of acrylic acid, After a copolymerization reaction was carried out at a temperature of about 60° C. using methanol as a solvent and azobisisobutyronitrile as a polymerization initiator, unreacted monomers were removed under reduced pressure to obtain a resin solution. Next, a solution of sodium hydroxide in methanol was added to cause a saponification reaction, which was thoroughly washed and then dried with a hot air dryer. Finally, polyvinyl alcohol resin no. 3 (PVA3) was obtained.
  • PVA3 polyvinyl alcohol resin no. 3
  • CMC1 carboxymethylcellulose sodium salt, weight average molecular weight 56000, degree of etherification 0.7
  • CMC2 carboxymethylcellulose sodium salt, weight average molecular weight 18000, degree of etherification 0.7 Methyl cellulose: weight average molecular weight 30000, degree of etherification 1.5
  • SWCNT1 single-walled carbon nanotube, specific surface area 1100 m 2 /g, outer diameter 1.56 nm, G/D ratio 100
  • SWCNT2 Single-walled carbon nanotube, specific surface area 1070 m 2 /g, outer diameter 1.3 nm
  • G/D ratio 87 MWCNT multi-walled carbon nanotube, specific surface area 170 m 2 /g, outer diameter 9 nm, G/D ratio 0.96
  • the G/D ratio of the carbon nanotubes, the impedance of the carbon nanotube dispersion, and the absorbance of the carbon nanotube dispersion were measured by the following methods.
  • the carbon nanotube dispersion was diluted with deionized water to prepare a CNT concentration of 0.001% by mass and stirred until uniform. Then, the sample was filled in a cell, and the absorbance at a wavelength (268 nm) was measured using U-1900 (trade name, spectrophotometer, manufactured by Hitachi High-Technologies Corporation).
  • Average particle size (D50) The obtained carbon nanotube dispersion is diluted with water to a measurement concentration and stirred, and a particle size distribution measuring device (manufactured by Microtrac Bell, product name: Microtrac MT3000) using a laser diffraction scattering method is used to measure volume-based Particle size distribution measurement was performed to calculate the average particle size (D50). Evaluation was made according to the following criteria. Basically, the smaller the average particle diameter (D50), the better. A and B are accepted, and C is rejected. A (very good): Average particle size (D50) is less than 4 ⁇ m. B (Good): The average particle size (D50) is 4 ⁇ m or more and less than 7 ⁇ m. C (poor): The average particle size (D50) is 7 ⁇ m or more.
  • the initial viscosity of the resulting carbon nanotube dispersion was measured at a shear rate of 5.0 sec ⁇ 1 using a cone and plate type viscometer (HAAKE, trade name: Mars2, diameter 35 mm, cone and plate inclined at 2°). It was measured and evaluated according to the following criteria. The lower the viscosity at the same concentration, the better. A and B are accepted, and C is rejected. The carbon nanotube dispersion liquid used for the measurement was used within 60 minutes immediately after the production of the carbon nanotube dispersion liquid. A (very good): The initial viscosity is less than 12 Pa ⁇ s. B (Good): The initial viscosity is 12 Pa ⁇ s or more and less than 15 Pa ⁇ s. C (poor): The initial viscosity is 15 Pa ⁇ s or more.
  • a and B are accepted, and C is rejected.

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PCT/JP2022/027496 2021-07-13 2022-07-13 リチウムイオン電池電極用カーボンナノチューブ分散液 Ceased WO2023286793A1 (ja)

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JP7848921B1 (ja) * 2025-05-22 2026-04-21 ａｒｔｉｅｎｃｅ株式会社 カーボンナノチューブ、カーボンナノチューブ分散液、バインダー組成物、電極用組成物、及び二次電池

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WO2026079394A1 (ja) * 2024-10-10 2026-04-16 日本ゼオン株式会社 二次電池電極用組成物セット、第１組成物、第２組成物、二次電池電極用組成物１、二次電池電極用組成物２、二次電池電極用組成物３、二次電池用電極および二次電池、ならびに、二次電池電極用組成物の製造方法

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JP2020189770A (ja) * 2019-05-23 2020-11-26 東洋インキＳｃホールディングス株式会社 カーボンナノチューブ分散液およびその利用
JP6860740B1 (ja) * 2020-04-27 2021-04-21 東洋インキＳｃホールディングス株式会社 カーボンナノチューブ分散液、それを用いた二次電池電極用組成物、電極膜、および二次電池。

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JP7848921B1 (ja) * 2025-05-22 2026-04-21 ａｒｔｉｅｎｃｅ株式会社 カーボンナノチューブ、カーボンナノチューブ分散液、バインダー組成物、電極用組成物、及び二次電池

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