WO2024063003A1 - Pâte pigmentaire électroconductrice, pâte de mélange et électrode pour batteries au lithium-ion - Google Patents

Pâte pigmentaire électroconductrice, pâte de mélange et électrode pour batteries au lithium-ion Download PDF

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Publication number
WO2024063003A1
WO2024063003A1 PCT/JP2023/033509 JP2023033509W WO2024063003A1 WO 2024063003 A1 WO2024063003 A1 WO 2024063003A1 JP 2023033509 W JP2023033509 W JP 2023033509W WO 2024063003 A1 WO2024063003 A1 WO 2024063003A1
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mass
conductive pigment
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pigment
paste
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PCT/JP2023/033509
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English (en)
Japanese (ja)
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敦史 塚本
陸矢 鈴木
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関西ペイント株式会社
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Priority to JP2023578968A priority Critical patent/JP7453487B1/ja
Publication of WO2024063003A1 publication Critical patent/WO2024063003A1/fr

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    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09C—TREATMENT OF INORGANIC MATERIALS, OTHER THAN FIBROUS FILLERS, TO ENHANCE THEIR PIGMENTING OR FILLING PROPERTIES ; PREPARATION OF CARBON BLACK  ; PREPARATION OF INORGANIC MATERIALS WHICH ARE NO SINGLE CHEMICAL COMPOUNDS AND WHICH ARE MAINLY USED AS PIGMENTS OR FILLERS
    • C09C1/00—Treatment of specific inorganic materials other than fibrous fillers; Preparation of carbon black
    • C09C1/44—Carbon
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
    • C09D127/00—Coating compositions based on homopolymers or 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 halogen; Coating compositions based on derivatives of such polymers
    • C09D127/02—Coating compositions based on homopolymers or 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 halogen; Coating compositions based on derivatives of such polymers not modified by chemical after-treatment
    • C09D127/12—Coating compositions based on homopolymers or 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 halogen; Coating compositions based on derivatives of such polymers not modified by chemical after-treatment containing fluorine atoms
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
    • C09D17/00—Pigment pastes, e.g. for mixing in paints
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
    • C09D5/00—Coating compositions, e.g. paints, varnishes or lacquers, characterised by their physical nature or the effects produced; Filling pastes
    • C09D5/24—Electrically-conducting paints
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
    • C09D7/00—Features of coating compositions, not provided for in group C09D5/00; Processes for incorporating ingredients in coating compositions
    • C09D7/20—Diluents or solvents
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
    • C09D7/00—Features of coating compositions, not provided for in group C09D5/00; Processes for incorporating ingredients in coating compositions
    • C09D7/40—Additives
    • C09D7/60—Additives non-macromolecular
    • C09D7/61—Additives non-macromolecular inorganic
    • 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
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers

Definitions

  • the present invention relates to a conductive pigment paste and composite material paste that have excellent pigment dispersibility and storage stability even at high pigment concentrations, and an electrode for lithium ion batteries coated with the composite material paste.
  • pigment dispersions in which pigments are dispersed in mixtures of pigment dispersion resins, solvents, etc. have been widely used in various fields. In these fields, improvements in performance such as pigment dispersibility, storage stability, coating properties, conductivity, finishing properties, and solvent resistance are increasingly required. Pigment dispersion resins and pigment pastes are being developed that have excellent storage stability that does not cause re-agglomeration of pigment particles in a pigment dispersion.
  • pigment paste When designing a pigment paste, make sure that the pigment dispersion resin does not have a negative effect on the performance of the final product itself, such as an electrode, or reduce the amount of solvent and pigment dispersion resin used, or reduce the energy used during drying. From this point of view, it is important to prepare a highly concentrated and uniformly dispersed pigment paste using a small amount of pigment dispersion resin. It is also important that the pigment paste can be stored for a long period of time without deterioration.
  • Patent Document 1 includes bundle-shaped carbon nanotubes, a dispersion medium, and a polyvinyl butyral resin having a weight average molecular weight of more than 50,000, and the dispersed particle size of the bundle-shaped carbon nanotubes is 3 to 3 in the particle size distribution D50.
  • Carbon nanotube dispersions that are 10 ⁇ m are described.
  • the electrode slurry containing the carbon nanotube dispersion liquid, electrode active material, and binder resin has good initial dispersibility, viscosity, and other properties, long-term storage performance may not be sufficient.
  • the problems to be solved by the present invention are conductive pigment pastes and composite pastes that have excellent pigment dispersibility and appropriate viscosity (low viscosity) even at high pigment concentrations, and excellent storage stability, as well as various performances (battery).
  • the purpose of the present invention is to provide an electrode for a lithium ion battery that has excellent performance (performance, etc.).
  • a conductive pigment paste containing a pigment dispersion resin (A), a conductive pigment (B), a solvent (C), a fluororesin (D), and a basic low molecular weight component (E),
  • the pigment dispersion resin (A) has at least one polar functional group, and the polar functional group concentration of the pigment dispersion resin (A) is 0.3 mmol/g to 23 mmol/g
  • the conductive pigment (B) contains carbon nanotubes (B1), When the content of the basic low molecular weight component (E) is ⁇ (parts by mass) with respect to 100 parts by mass of the carbon nanotube (B1), and the BET specific surface area of the carbon nanotube (B1) is ⁇ (m 2 /g).
  • the pigment dispersion resin (A) has at least one polar functional group, and the polar functional group concentration of the pigment dispersion resin (A) is 0.3 mmol/g to 23 mmol/g
  • the conductive pigment (B) contains carbon nanotubes (B1),
  • the content of the basic low molecular weight component (E) with respect to 100 parts by mass of the carbon nanotube (B1) is ⁇ (parts by mass), the BET specific surface area of the carbon nanotube (B1) is ⁇ (m 2 /g), and the carbon nanotube
  • the BET specific surface area of the carbon nanotube (B1) is 100 m 2 /g to 800 m 2 /g, and the maximum within the range of 1560 m ⁇ 1 to 1600 cm ⁇ 1 in the Raman spectrum of the carbon nanotube (B1).
  • the G/D ratio is 0.1 to 5, where the peak intensity is G and the maximum peak intensity within the range of 1310 m -1 to 1350 cm -1 is D.
  • conductive pigment paste is 0.1 to 5, where the peak intensity is G and the maximum peak intensity within the range of 1310 m -1 to 1350 cm -1 is D.
  • the conductive pigment paste and composite material paste of the present invention have excellent pigment dispersibility and appropriate viscosity (low viscosity) even at high pigment concentrations, excellent storage stability, and excellent electrical conductivity of the coating film. Furthermore, the lithium ion battery electrode obtained by applying the composite material paste has excellent various performances (battery performance, etc.).
  • the present invention is not limited to the following embodiments, but should be understood to include various modifications that may be implemented without departing from the gist of the present invention.
  • the "specific surface area" refers to the BET specific surface area determined by the nitrogen adsorption method.
  • a conductive pigment paste having a conductive pigment in an appropriately dispersed state is prepared.
  • a composite paste is produced by adding components such as an electrode active material to the conductive pigment paste.
  • the conductive pigment paste of the first aspect of the present invention contains a pigment dispersion resin (A), a conductive pigment (B), a solvent (C), a fluororesin (D), and a basic low molecular weight component (E).
  • the conductive pigment (B) contains carbon nanotubes (B1), and the content of the basic low molecular weight component (E) with respect to 100 parts by mass of the carbon nanotubes (B1) is ⁇ (parts by mass),
  • a conductive pigment paste in which the value of X in the following formula (1) is 5 or more is suitable.
  • X ⁇ / ⁇ 300...Formula (1)
  • the value of More preferably it is 500 or less, still more preferably 300 or less.
  • a suitable range is preferably 5 or more and 2,500 or less, more preferably 10 or more and 1,000 or less, still more preferably 40 or more and 500 or less, particularly preferably 60 or more and 300 or less.
  • the surface of the carbon nanotubes (B1) can be sufficiently wetted with the basic low molecular weight component (E), and the dispersibility (including viscosity) and storage stability (increase) of the carbon nanotubes (B1) can be improved. It has been found that the properties (including viscosity control) can be improved. If the content of the basic low molecular weight component (E) is excessive with respect to the BET specific surface area of the carbon nanotubes (B1), the odor becomes strong and the cost increases. If the content is insufficient, the basic low molecular weight component (E) content may be insufficient relative to the BET specific surface area of the carbon nanotubes (B1), resulting in poor dispersibility and storage stability (suppression of viscosity increase).
  • the conductive pigment paste of the second aspect of the present invention includes a pigment dispersion resin (A), a conductive pigment (B), a solvent (C), a fluororesin (D), and a basic low molecular weight component (E ), wherein the pigment dispersion resin (A) has at least one kind of polar functional group, and the polar functional group concentration of the pigment dispersion resin (A) is 0.3 mmol/g to 23 mmol. /g, the conductive pigment (B) contains carbon nanotubes (B1), and the content of the basic low molecular weight component (E) is ⁇ (parts by mass) with respect to 100 parts by mass of the carbon nanotubes (B1).
  • the BET specific surface area of the carbon nanotube (B1) is ⁇ (m 2 /g)
  • the amount of acidic groups of the carbon nanotube (B1) is ⁇ (mmol/g)
  • the value of Y in the following formula (2) is , 0.01 or more is suitable.
  • Y ⁇ / ⁇ / ⁇ ...Formula (2)
  • the value of Y is preferably 0.01 or more, more preferably 1 or more, even more preferably 2 or more, particularly preferably 3 or more, for example 400 or less, preferably 200 or less. Yes, more preferably 150 or less, still more preferably 100 or less.
  • a suitable range is preferably 0.01 or more and 400 or less, more preferably 1 or more and 200 or less, still more preferably 2 or more and 150 or less, and particularly preferably 3 or more and 100 or less.
  • the surface of the carbon nanotube (B1) having a certain amount of acidic groups can be sufficiently wetted with the basic low molecular weight component (E), and the dispersibility (including viscosity) of the carbon nanotube (B1) ) and storage stability (including inhibition of thickening). If the content of the basic low molecular weight component (E) is excessive with respect to the BET specific surface area of the carbon nanotube (B1) having an acidic group, the odor becomes strong and the cost increases.
  • the basic low molecular weight component (E) content may be insufficient relative to the BET specific surface area of the carbon nanotube (B1) having acidic groups, resulting in poor dispersibility and storage stability (inhibition of thickening). .
  • Pigment dispersion resin (A) has at least one polar functional group selected from the group consisting of an amide group, an imide group, a hydroxyl group, a carboxyl group, a sulfonic acid group, a phosphoric acid group, a silanol group, a cyano group, a pyrrolidone group, and an ether group. group, and the polar functional group concentration of the pigment dispersion resin (A) is 0.3 mmol/g to 23 mmol/g.
  • the above acid group may be in the form of a salt.
  • the type of resin is not particularly limited as long as it is a resin other than the fluororesin (D) described below.
  • acrylic resin polyester resin, epoxy resin, polyether resin, alkyd resin, urethane resin, polyvinyl alcohol, polyvinyl acetal, polyvinylpyrrolidone, polyvinyl acetate, silicone resin, polycarbonate resin, chlorine resin, and composite resins thereof, etc. can be mentioned.
  • These resins can be used alone or in combination of two or more.
  • the pigment dispersion resin (A) a monomer containing a polymerizable unsaturated group-containing monomer of the following formula (1) is polymerized or copolymerized. It is preferable to contain a vinyl (co)polymer (A1) obtained by.
  • the "(co)polymer" of the present invention includes both a polymer obtained by polymerizing one type of monomer and a copolymer obtained by copolymerizing two or more types of monomers.
  • C(-R) 2 C(-R) 2 Formula (1)
  • R may be the same or different and is a hydrogen atom or an organic group.
  • the vinyl (co)polymer (A1) preferably contains in its structure a structural unit represented by "-CH 2 -CH(-X)-" (wherein X is an active hydrogen group or an organic group containing an active hydrogen group).
  • Examples of the vinyl (co)polymer (A1) include hydroxyl group-containing vinyl (co)polymers, carboxyl group-containing vinyl (co)polymers, amide group-containing vinyl (co)polymers, sulfonic acid group-containing vinyl (co)polymers, phosphate group-containing vinyl (co)polymers, and pyrrolidone group-containing vinyl (co)polymers. These (co)polymers may be used alone or in combination of two or more.
  • hydroxyl group-containing vinyl (co)polymer examples include polyhydroxyalkyl (meth)acrylate (such as polyhydroxyethyl (meth)acrylate), polyvinyl alcohol, vinyl alcohol-fatty acid vinyl copolymer, and vinyl alcohol-ethylene copolymer. , vinyl alcohol-(N-vinylformamide) copolymers, copolymers of hydroxyalkyl (meth)acrylates (such as hydroxyethyl (meth)acrylate) and other polymerizable unsaturated monomers, and the like.
  • the vinyl alcohol units in the (co)polymer may be those obtained by (co)polymerizing fatty acid vinyl units and then hydrolyzing them.
  • carboxyl group-containing vinyl (co)polymer examples include a polymer of (meth)acrylic acid, a copolymer of (meth)acrylic acid and other polymerizable unsaturated monomers, and the like.
  • Examples of the amide group-containing vinyl (co)polymer include a polymer of (meth)acrylamide, a polymer of (meth)acrylamide derivatives (such as 3-(meth)acrylamidopropyltrimethylammonium chloride, or a polymer of (meth)acrylamide and others). Examples include copolymers with polymerizable unsaturated monomers.
  • sulfonic acid group-containing vinyl (co)polymer examples include polymers of allylsulfonic acid or styrenesulfonic acid, copolymers of allylsulfonic acid and/or styrenesulfonic acid, and other polymerizable unsaturated monomers, etc. can be mentioned.
  • Examples of the phosphoric acid group-containing vinyl (co)polymer include a polymer of (meth)acryloyloxyalkyl acid phosphate, or a copolymer of (meth)acryloyloxyalkyl acid phosphate and other polymerizable unsaturated monomers. can be mentioned.
  • the vinyl (co)polymer (A1) contains, in addition to the structural unit represented by "-CH 2 --CH(-X)-", a polymerizable unsaturated group-containing monomer that can be copolymerized as necessary. may contain structural units derived from Examples of copolymerizable polymerizable unsaturated group-containing monomers include vinyl formate, vinyl acetate, vinyl propionate, isopropenyl acetate, vinyl valerate, vinyl caprylate, vinyl caprate, vinyl laurate, vinyl stearate, Carboxylic acid vinyl ester monomers such as vinyl benzoate, vinyl versatate, and vinyl pivalate; Olefins such as ethylene, propylene, and butylene; Aromatic vinyls such as styrene and ⁇ -methylstyrene; (meth)acrylic acid Ethylenically unsaturated carboxylic acids such as methyl, ethyl (meth)acrylate, n-butyl (meth)acrylate
  • Alkyl ester monomer such as methyl vinyl ether, n-propyl vinyl ether, isobutyl vinyl ether, dodecyl vinyl ether; Vinyl halide monomer or vinylidene monomer such as vinyl chloride, vinylidene chloride, vinyl fluoride, vinylidene fluoride, etc. Allyl compounds such as allyl acetate and allyl chloride; Quaternary ammonium group-containing monomers such as vinyltrimethoxysilane, N-vinylformamide, and N-vinyl-2-pyrrolidone. These monomers can be used alone or in combination of two or more.
  • the polar functional group concentration of the pigment dispersion resin (A) is usually 0.3 mmol/g to 23 mmol/g, preferably 9 mmol/g from the viewpoint of pigment dispersibility, storage stability, and compatibility with solvents. It is preferable that the amount is 23 mmol/g.
  • the vinyl (co)polymer (A1) can be produced by a known polymerization method, for example, it is preferable to use solution polymerization, but it is not limited to this, and bulk polymerization or emulsification is preferred. Polymerization, suspension polymerization, etc. may be used. When solution polymerization is carried out, it may be continuous or batch polymerization, and the monomers may be charged all at once, divided into portions, or added continuously or intermittently.
  • the polymerization initiator used in solution polymerization is not particularly limited, but specifically, for example, azobisisobutyronitrile, azobis-2,4-dimethylparellonitrile, azobis(4-methoxy-2 azo compounds such as acetyl peroxide, benzoyl peroxide, lauroyl peroxide, acetylcyclohexylsulfonyl peroxide, 2,4,4-trimethylpentyl-2-peroxyphenoxyacetate, etc.
  • Percarbonate compounds such as diisopropyl peroxydicarbonate, di-2-ethylhexyl peroxydicarbonate, diethoxyethyl peroxydicarbonate; t-butyl peroxyneodecanate, ⁇ -cumyl peroxyneodecanate , perester compounds such as t-butylperoxyneodecanate; known radical polymerization initiators such as azobisdimethylvaleronitrile and azobismethoxyvaleronitrile can be used. These can be used alone or in combination of two or more.
  • the polymerization reaction temperature is not particularly limited, but can usually be set within a range of about 30°C or higher and 200°C or lower.
  • the vinyl (co)polymer (A1) that can be obtained as described above has a degree of polymerization of, for example, 100 or more, preferably 150 or more, and for example, 4,000 or less, preferably 3,000 or less, more preferably 700 or less.
  • the weight average molecular weight is, for example, 500 or more, preferably 1,000 or more, more preferably 2,000 or more, still more preferably 7,000 or more, and for example 2,000,000 or less, preferably 1,000 or more. ,000 or less, more preferably 500,000 or less.
  • the weight average molecular weight is usually in the range of 500 to 50,000, more preferably in the range of 1,000 to 20,000, and more particularly in the range of 1,500 to 20,000, from the viewpoint of finishability, corrosion resistance, etc. Preferably, it is within the range of 000.
  • the weight average molecular weight in this specification is based on the retention time (retention capacity) measured using gel permeation chromatography (GPC) of standard polystyrene with a known molecular weight measured under the same conditions. This value is calculated by converting the retention time (retention capacity) into the molecular weight of polystyrene.
  • HLC8120GPC (trade name, manufactured by Tosoh Corporation) was used as a gel permeation chromatograph, and "TSKgel G-4000HXL”, “TSKgel G-3000HXL”, and “TSKgel G-2500HXL” were used as columns.
  • TSKgel G-2000HXL (trade names, both manufactured by Tosoh Corporation), and can be measured under the conditions of a mobile phase of tetrahydrofuran, a measurement temperature of 40° C., a flow rate of 1 mL/min, and a detector RI.
  • the above vinyl (co)polymer (A1) can be made into a solid or a resin solution substituted with an arbitrary solvent by removing the solvent and/or replacing the solvent after completion of the synthesis.
  • the solvent may be removed by heating at normal pressure or under reduced pressure.
  • a replacement solvent may be introduced at any stage before desolvation, during desolvation, or after desolvation.
  • the solid content of the pigment dispersion resin (A) is, for example, 0.1% by mass or more, preferably 1% by mass or more, more preferably 3% by mass or more, based on the total solid content of the conductive pigment paste. For example, it is 40% by mass or less, preferably 20% by mass or less, more preferably 15% by mass or less.
  • the solid content of the pigment dispersion resin (A) is, based on the content of the conductive pigment (B), for example, 0.1% by mass or more, preferably 1% by mass or more, more preferably 5% by mass or more, and for example, 50% by mass or less, preferably 40% by mass or less, more preferably 30% by mass or less.
  • the conductive pigment (B) contains carbon nanotubes (B1).
  • the conductive pigment (B) may further contain a conductive pigment (B2) other than the carbon nanotubes (B1).
  • the content of carbon nanotubes (B1) in the conductive pigment (B) is preferably 50% by mass or more, more preferably 75% by mass or more, and 95% by mass, based on 100% by mass of the conductive pigment (B). % or more is more preferable.
  • Carbon nanotube (B1)) As the carbon nanotubes (B1), single-walled carbon nanotubes or multi-walled carbon nanotubes can be used alone or in combination. In particular, from the viewpoint of viscosity, conductivity, and cost, it is preferable to use multi-walled carbon nanotubes.
  • the average outer diameter of the carbon nanotubes (B1) is, for example, 1 nm or more, preferably 3 nm or more, more preferably 5 nm or more, and is, for example, 30 nm or less, preferably 28 nm or less, more preferably 25 nm or less.
  • the average length of the carbon nanotubes (B1) is, for example, 0.1 ⁇ m or more, preferably 1 ⁇ m or more, more preferably 5 ⁇ m or more, and is, for example, 100 ⁇ m or less, preferably 80 ⁇ m or less, more preferably 60 ⁇ m or less.
  • the BET specific surface area of the carbon nanotubes (B1) is, for example, 100 m 2 /g, preferably 130 m 2 /g, more preferably 160 m 2 /g, for example 800 m 2 from the viewpoint of viscosity and conductivity. /g, preferably 600 m 2 /g or less, more preferably 400 m 2 /g or less.
  • the amount of acidic groups in the carbon nanotubes (B1) is, for example, 0.01 mmol/g to 0.5 mmol/g, preferably 0.01 mmol/g to 0.2 mmol/g, from the viewpoint of dispersibility and storage stability. and more preferably 0.01 mmol/g to 0.1 mmol/g. If the amount of acidic groups is 0.01 mmol/g or more, the dispersibility will be good, and if the amount is 1.0 mmol/g or less, the storage stability will be good.
  • the above acidic group can be provided by the following acid treatment of carbon nanotubes.
  • the acid treatment method is not particularly limited as long as the acid can be brought into contact with the carbon nanotubes, but a method of immersing the carbon nanotubes in an acid treatment solution (aqueous acid solution) is preferred.
  • an acid treatment solution aqueous acid solution
  • the acid contained in the acid treatment liquid is not particularly limited, examples thereof include nitric acid, sulfuric acid, and hydrochloric acid. These can be used alone or in combination of two or more. Among these, nitric acid and sulfuric acid are preferred.
  • the amount of acidic groups in carbon nanotubes can be adjusted by adjusting the concentration, temperature, treatment time, etc. of the acid treatment solution.
  • acid-treated carbon nanotubes can be obtained.
  • the method for washing the acid-treated carbon nanotubes is not particularly limited, but washing with water is preferred.
  • carbon nanotubes are recovered from acid-treated carbon nanotubes by a known method such as filtration, and then the carbon nanotubes are washed with water. After the above washing, water adhering to the surface may be removed by drying, if necessary, to obtain acid-treated carbon nanotubes.
  • the volume-converted median diameter (D50) of the carbon nanotube (B1) is, for example, 10 ⁇ m or more, preferably 15 ⁇ m or more, and more preferably 20 ⁇ m or more, when measured by the method described in Examples. , for example, 250 ⁇ m or less, preferably 200 ⁇ m or less, and more preferably 150 ⁇ m or less.
  • the median diameter (D50) can be determined by irradiating carbon nanotube particles with a laser beam and converting the diameter of the carbon nanotube into a sphere from the scattered light. The larger the median diameter (D50), the more aggregates of carbon nanotubes are present, which means that the dispersibility is poor.
  • the median diameter (D50) is larger than 250 ⁇ m, there is a high possibility that aggregates of carbon nanotubes will exist in the electrode, resulting in non-uniform conductivity throughout the electrode.
  • the median diameter (D50) is smaller than 10 ⁇ m, the conductive path is insufficient because the fiber length is short, and the conductivity decreases.
  • the median diameter (D50) is within the range of 10 to 250 ⁇ m, carbon nanotubes can be uniformly dispersed within the electrode while maintaining conductivity.
  • the maximum peak intensity within the range of 1560 cm -1 to 1600 cm -1 is designated as G
  • the maximum peak intensity within the range of 1310 cm -1 to 1350 cm -1 is designated as D.
  • the G/D ratio is, for example, 0.1 or more, preferably 0.4 or more, more preferably 0.6 or more, for example 5.0 or less, preferably 3.0 or less. Yes, and more preferably 1.0 or less.
  • it is preferable that the G/D ratio is within the range of 0.1 to 5.0 because there are fewer defects and crystal interfaces on the carbon surface and the conductivity tends to be high.
  • conductive pigments (B2) other than carbon nanotubes (B1) are not particularly limited, and include, for example, at least one kind selected from the group consisting of acetylene black, Ketjen black, furnace black, thermal black, graphene, and graphite. Examples include conductive carbon. Preferably, it is one or more selected from the group consisting of acetylene black, Ketjen black, furnace black, and thermal black, more preferably one or more selected from the group consisting of acetylene black, Ketjen black, and Preferably it is one or more types of acetylene black.
  • the average primary particle diameter of the other conductive pigment (B2) is preferably 10 to 80 nm, more preferably 20 to 70 nm.
  • the average primary particle diameter is determined by observing the conductive carbon (B2) with an electron microscope, determining the projected area of each of 100 particles, and determining the diameter assuming a circle equal to the area.
  • the average diameter of primary particles is determined by simply averaging the diameters of the particles. Note that if the pigment is in an aggregated state, calculations are performed using the primary particles that make up the aggregated particles.
  • the BET specific surface area of the conductive carbon (B2) is not particularly limited. In terms of viscosity and conductivity, it is, for example, 1 m 2 /g or more, preferably 10 m 2 /g or more, more preferably 20 m 2 /g or more, and for example 500 m 2 /g or less, preferably 250 m 2 /g or less. , more preferably 200 m 2 /g or less.
  • the dibutyl phthalate (DBP) oil absorption amount of the conductive carbon (B2) is not particularly limited.
  • the amount is, for example, 60 ml/100 g or more, preferably 150 ml/100 g or more, and is, for example, 1,000 ml/100 g or less, preferably 800 ml/100 g or less.
  • the solid content of the conductive pigment (B) is, for example, 10.0% by mass or more, preferably 30.0% by mass, based on the total solid content of the conductive pigment paste. As mentioned above, it is more preferably 40.0% by mass or more, for example, 99.0% by mass or less, preferably 80.0% by mass or less, more preferably 60.0% by mass or less.
  • Solvent (C) As the solvent (C), water, various organic solvents, etc. can be suitably used. Specifically, for example, water; hydrocarbon solvents such as n-butane, n-hexane, n-heptane, n-octane, cyclopentane, cyclohexane, and cyclobutane; aromatic solvents such as toluene and xylene; n- Ether solvents such as butyl ether, dioxane, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol; ethyl acetate, n-butyl acetate, isobutyl acetate, ethylene glycol monomethyl ether acetate, butyl carbitol acetate, Ester solvents; Ketone solvents such as methyl ethyl ketone, methyl isobutyl ketone, and
  • the conductive pigment paste does not substantially contain water.
  • substantially free of water means that the water content is usually 1% by mass or less, preferably 0.5% by mass or less, and especially It is preferably 0.1% by mass or less.
  • the water content of the conductive pigment paste can be measured by Karl Fischer coulometric titration.
  • a Karl Fischer moisture content meter (manufactured by Kyoto Denshi Kogyo Co., Ltd., trade name: MKC-610) was used, and the settings of a moisture vaporizer (manufactured by Kyoto Denshi Kogyo Co., Ltd., trade name ADP-611) included in the device were performed.
  • the temperature can be measured as 130°C.
  • an amide compound (solvent) such as N-methyl-2-pyrrolidone
  • it may contain an amine component as an impurity, and in the conductive pigment paste of the present invention, the viscosity or Thickening trends were sometimes different.
  • the solvent etc. will volatilize and will not remain. It is preferable to collect and reuse. That is, it is preferable to use a recycled product as the solvent (C).
  • This recycled solvent (recycled product) also contains the amine compound (E1) originally contained in the conductive pigment paste of the present invention, and the viscosity or thickening tendency of the conductive pigment paste varies from lot to lot. It will be different.
  • amine compounds often have a strong odor. Therefore, it is preferable to control and adjust the amine compound content in the recycled solvent (C) to a certain amount or less, and the amine compound content is usually 1% by mass or less, preferably 0.5% by mass. % or less, particularly preferably 0.1% by mass or less.
  • the above-mentioned "using a recycled product as the solvent (C)" means that the solvent (C) used in the conductive pigment paste of the present invention contains 10% or more (preferably 20% or more) of a recycled product. It is.
  • the content of the solvent (C) in the conductive pigment paste is, for example, 40% by mass or more, preferably 60% by mass or more, more preferably 80% by mass or more, for example 99% by mass, based on the total amount of the conductive pigment paste. % or less, preferably 98% by mass or less, more preferably 97% by mass or less.
  • the solubility parameter ⁇ A of the pigment dispersion resin (A) and the solubility parameter ⁇ C of the solvent (C) have a relationship of
  • the solubility parameter ⁇ C of the solvent (C) itself is preferably 10.0 or more, more preferably 10.5 or more, preferably 12.0 or less, and more preferably 11.5 or less.
  • the solubility parameter of the resin is numerically quantified based on the turbidity measurement method known to those skilled in the art. 2359, 1968).
  • the solubility parameter of a solvent can be determined according to the method described in "Polymer Handbook VII" edited by J. Brandrup and EHImmergut, Solubility Parameter Values, pp519-559 (John Wiley & Sons, 3rd edition published in 1989).
  • the solubility parameter of the mixed solvent can be determined experimentally. It can also be determined by the sum of products with solubility parameters.
  • the unit of solubility parameter is "(cal/cm 3 ) 1/2 ".
  • Fluororesin (D) is a resin intended for forming an electrode layer.
  • PVDF polyvinylidene fluoride
  • the fluororesin (D) may be contained during pigment dispersion, or may be added and contained after pigment dispersion.
  • the weight average molecular weight of the fluororesin (D) is preferably 100,000 or more, more preferably 500,000, and more preferably 650,000 or more from the viewpoints of adhesion to the base material, reinforcement of film physical properties, and solvent resistance. is more preferable, preferably 3 million or less, and more preferably 2 million or less.
  • the content of the fluororesin (D) is, for example, 10.0% by mass or more, preferably 30.0% by mass or more, more preferably 40.0% by mass or more, based on the solid content of the conductive pigment paste, For example, it is 99.0% by mass or less, preferably 80.0% by mass or less, more preferably 60.0% by mass or less.
  • the basic low molecular weight component (E) may be either an inorganic base compound or an organic base compound.
  • hydroxides such as lithium hydroxide, barium hydroxide, sodium hydroxide, potassium hydroxide
  • metal hydrides such as sodium hydride, potassium hydride
  • Phosphates such as trisodium phosphate and tripotassium phosphate
  • Acetate salts such as lithium acetate, sodium acetate, and potassium acetate
  • Sodium methoxide, sodium ethoxide Examples include alkoxide compounds such as potassium tertiary butoxide; amine compounds such as ammonia, primary amines, secondary amines, and tertiary amines; and the like.
  • the molecular weight of the basic low molecular weight component (E) is, for example, less than 1000, preferably 500 or less, more preferably 350 or less, still more preferably 250 or less, particularly preferably 120 or less.
  • the basic low molecular weight component (E) preferably contains an amine compound (E1) from the viewpoint of improving the wettability and/or storage stability of the conductive pigment.
  • the content of the amine compound (E1) in the basic low molecular weight component (E) is preferably 50% by mass or more, more preferably 75% by mass or more, based on 100% by mass of the basic low molecular weight component (E). It is preferably 95% by mass or more, and more preferably 95% by mass or more.
  • Examples of the amine compound (E1) include ammonia, primary amines, secondary amines, tertiary amines, and the like.
  • Primary amines include, for example, ethylamine, n-propylamine, sec-propylamine, n-butylamine, sec-butylamine, i-butylamine, tert-butylamine, pentylamine, hexylamine, heptylamine, octylamine, decylamine, laurylamine, myristyrylamine, 1,2-dimethylhexylamine, 3-pentylamine, 2-ethylhexylamine, allylamine, aminoethanol, 1-aminopropanol, 2-aminopropanol, aminobutanol, aminopentanol, aminohexanol, 3-ethoxypropylamine, 3-propoxypropylamine, 3-isopropoxypropylamine, 3-butoxypropylamine, 3-isopropoxypropylamine, 3-butoxypropylamine, 3-isobutoxypropylamine, 3-(2-ethyl
  • secondary amines include diethylamine, dipropylamine, di-n-butylamine, di-sec-butylamine, diisobutylamine, di-n-pentylamine, di-3-pentylamine, dihexylamine, dioctylamine, di- (2-ethylhexyl)amine, methylhexylamine, diallylamine, pyrrolidine, piperidine, 2,4-lupetidine, 2,6-lupetidine, 3,5-lupetidine, diphenylamine, N-methylaniline, N-ethylaniline, dibenzylamine , methylbenzylamine, dinaphthylamine, pyrrole, indoline, indole, morpholine and other secondary monoamines; N,N'-dimethylethylenediamine, N,N'-dimethyl-1,2-diaminopropane, N,N'-dimethyl- 1,3-d
  • tertiary amine examples include trimethylamine, triethylamine, tri-n-propylamine, tri-iso-propylamine, tri-1,2-dimethylpropylamine, tri-3-methoxypropylamine, tri-n-butylamine, Tri-iso-butylamine, tri-sec-butylamine, tri-pentylamine, tri-3-pentylamine, tri-n-hexylamine, tri-n-octylamine, tri-2-ethylhexylamine, tri-dodecylamine, Tri-laurylamine, dicyclohexylethylamine, cyclohexyldiethylamine, tri-cyclohexylamine, N,N-dimethylhexylamine, N-methyldihexylamine, N,N-dimethylcyclohexylamine, N-methyldicyclohexylamine, N,N-diethylethanol
  • the amine compound (E1) examples include aliphatic amines, alicyclic amines, aromatic amines, etc., and any of them can be preferably used, but aromatic amines, primary aliphatic amine compounds having a hydroxyl group, A secondary aliphatic amine compound having the following is preferable, and a primary aromatic amine compound is more preferable.
  • the nitrogen atoms in the amine compound (E1) are only nitrogen atoms constituting an amino group.
  • the amine compound (E1) preferably has 3 or less nitrogen atoms, more preferably 2 or less, and even more preferably 1 nitrogen atom.
  • the amine compound (E1) is preferably not an amine compound having a triazine ring in the molecule.
  • the aliphatic amine compound should be mixed in an amount exceeding 1 molar equivalent per 1 molar equivalent of the amine compound having a triazine ring. is preferred.
  • the molecular weight thereof is less than 116.
  • the weight average molecular weight of the amine compound (E1) is preferably less than 1000, more preferably 500 or less, and even more preferably 350 or less. It is preferably 250 or less, particularly preferably 120 or less, and even more preferably 120 or less.
  • the primary aliphatic amine compound having a hydroxyl group is preferably a primary aliphatic amine compound having a hydroxyl group and having a weight average molecular weight of 89 or more.
  • the boiling point of the amine compound is preferably 400°C or lower, more preferably 300°C or lower, and even more preferably 200°C or lower.
  • the amine value of the amine compound (E1) is, for example, 5 mgKOH/g or more, preferably 105 mgKOH/g or more, more preferably 250 mgKOH/g or more, still more preferably 400 mgKOH/g or more, and, for example, 1000 mgKOH/g or less. Preferably, it is within this range.
  • the content of the basic low molecular weight component (E) is, for example, 1% by mass or more, preferably 10% by mass or more, more preferably 40% by mass or more, based on 100% by mass of the solid content of the conductive pigment paste.
  • it is preferably 300% by mass or less, preferably 200% by mass or less, more preferably 150% by mass or less.
  • the lower limit is, for example, 1% by mass or more, preferably 12% by mass or more, more preferably 40% by mass or more, still more preferably 80% by mass or more, based on 100% by mass of the solid content of the conductive pigment (B). It is.
  • the upper limit is, for example, 1000% by mass or less, preferably 500% by mass or less, more preferably 350% by mass or less, still more preferably 300% by mass or less.
  • the basic low molecular weight component (E) especially the amine compound (E1)] often has a strong odor, the working environment may deteriorate during the blending or drying process. Furthermore, since they are generally expensive, the cost may increase. Therefore, it is necessary to keep the content to the minimum necessary.
  • the content ratio of the solvent (C) and the basic low molecular weight component (E) is usually 100/0.1 to 100/10 in mass ratio of the solvent (C) and the basic low molecular weight component (E). within the range, preferably within the range of 100/0.5 to 100/8, more preferably within the range of 100/1 to 100/6, and more preferably 100/1.5 to 100/4. It is preferable that it be within the range of .
  • the conductive pigment paste of the present invention may contain other components as necessary. can do.
  • pigments include, for example, resins other than pigment dispersion resin (A) and fluororesin (D), neutralizers, antifoaming agents, preservatives, rust preventives, plasticizers, and conductive pigments other than (B). Examples include pigments.
  • Pigments other than the conductive pigment (B) include, for example, white pigments such as titanium white and zinc white; blue pigments such as cyanine blue and industhrene blue; green pigments such as cyanine green and verdigris; azo-based and quinacridone-based pigments, etc.
  • Red pigments such as organic red pigments and red pigments
  • organic yellow pigments such as benzimidazolone series, isoindolinone series, isoindoline series, and quinophthalone series
  • yellow pigments such as titanium yellow and yellow lead; These pigments can be used alone or in combination of two or more.
  • Pigments other than these conductive pigments (B) can be used for purposes such as color adjustment and reinforcing the physical properties of the film within a range that does not significantly impair conductivity. It may be dispersed simultaneously with B), or it may be mixed as a pigment or a pigment paste after a paste is prepared by dispersing the pigment dispersion resin (A) and the conductive pigment (B).
  • the content of pigments other than the conductive pigment (B) is preferably 10% by mass or less, more preferably 5% by mass or less, even more preferably 1% by mass or less, based on the total pigments in the conductive pigment paste. It is particularly preferable that it does not substantially contain it. Moreover, it is preferable that the conductive pigment paste of the present invention does not contain a pigment derivative. In particular, it is preferable not to contain a triazine-based pigment derivative containing a triazine ring in the molecule.
  • the viscosity of the conductive pigment paste at a shear rate of 2 s -1 is less than 5000 mPa ⁇ s, preferably less than 2500 mPa ⁇ s, and 1000 mPa ⁇ s. s, and 10 mPa ⁇ s or more, preferably 50 mPa ⁇ s or more, and more preferably 100 mPa ⁇ s or more.
  • it is preferably 10 mPa ⁇ s or more and less than 5000 mPa ⁇ s, more preferably 50 mPa ⁇ s or more and less than 2500 mPa ⁇ s, and particularly preferably 100 mPa ⁇ s or more and less than 1000 mPa ⁇ s.
  • the viscosity can be measured using, for example, a cone and plate viscometer (manufactured by HAAKE, trade name: Mars2, diameter 35 mm, 2° inclination cone and plate).
  • a cone and plate viscometer manufactured by HAAKE, trade name: Mars2, diameter 35 mm, 2° inclination cone and plate.
  • the conductive pigment paste of the present invention can be prepared using a paint shaker, a sand mill, a ball mill, a pebble mill, a LMZ mill, a DCP pearl mill, a planetary ball mill, a homogenizer, a twin-screw kneader, a thin film rotating high-speed mixer ( It can be prepared by uniformly mixing and dispersing using a conventionally known dispersing machine such as (trade name: CLEAR MIX, FIL MIX, etc.).
  • the present invention provides a composite paste formed by further blending an electrode active material (F) with the above conductive pigment paste.
  • the composite paste is suitable for use as a positive electrode or a negative electrode for a lithium ion battery electrode, and preferably as a positive electrode.
  • the second aspect of the composite material paste of the present invention includes a pigment dispersion resin (A), a conductive pigment (B), a solvent (C), a fluororesin (D), a basic low molecular weight component (E), and Contains an electrode active material (F), and the pigment dispersion resin (A) consists of an amide group, an imide group, a hydroxyl group, a carboxyl group, a sulfonic acid group, a phosphoric acid group, a silanol group, a cyano group, a pyrrolidone group, and an ether group.
  • the conductive pigment (B) has at least one polar functional group selected from the group consisting of carbon nanotubes ( The manufacturing method (order of mixing the components) is not limited as long as it contains B1).
  • Electrode active material (F) examples include lithium nickelate (LiNiO 2 ), lithium manganate (LiMn 2 O 4 ), lithium cobalt oxide (LiCoO 2 ), and LiNi 1/3 Co 1/3 Mn 1/3 O.
  • Lithium composite oxides such as No. 2 ; lithium iron phosphate (LiFePO 4 ); sodium composite oxides; potassium composite oxides, and the like.
  • the electrode active material containing lithium iron phosphate is inexpensive and has relatively good cycle characteristics and energy density, so it can be suitably used.
  • the particle size of the electrode active material is, for example, 0.5 ⁇ m or more, preferably 10.5 ⁇ m or more, and, for example, 30 ⁇ m or less, preferably 20 ⁇ m or less.
  • the solid content of the electrode active material (F) in the solid content of the composite paste of the present invention is usually 70% by mass or more and less than 100% by mass, preferably 80% by mass or more and less than 100% by mass. is preferable from the viewpoint of battery capacity, battery resistance, etc.
  • the composite paste contains the electrode active material (F), it may thicken during storage.
  • the electrode active material (F) has alkali metal hydroxides (e.g., LiOH, KOH, NaOH, etc.) derived from the raw materials on the particle surface, and is thought to aggregate (thicken) due to the conductive pigment (B) having an acidic surface. Therefore, by containing a certain amount or more of a basic low molecular weight component (E) [particularly an amine compound (E1)], it is possible to suppress the thickening of the composite paste during storage.
  • a basic low molecular weight component (E) particularly an amine compound (E1)
  • the composite material paste of the present invention can be obtained by first preparing the above-mentioned conductive pigment paste, and then blending at least one type of electrode active material (F) into the paste. Further, the composite material paste of the present invention may be prepared by mixing the aforementioned components (A), (B), (C), (D), (E), and the electrode active material (F).
  • the solid content of the pigment dispersion resin (A) in the solid content of the composite material paste of the present invention is, for example, 0.01% by mass or more, preferably 0.02% by mass or more, and, for example, 20% by mass or less, preferably The content is preferably 10% by mass or less in terms of battery performance, paste viscosity, etc.
  • the composite paste of the present invention contains a basic low molecular weight component (E) from the viewpoint of storage stability (suppression of thickening) in the composite paste.
  • E basic low molecular weight component
  • the lower limit of the content of the basic low molecular weight component (E) based on the solid content of the conductive pigment (B) is 100% by mass.
  • the content is usually 1% by mass or more, preferably 10% by mass or more, more preferably 40% by mass or more, and still more preferably 80% by mass or more.
  • the upper limit is usually 500% by mass or less, preferably 400% by mass or less, more preferably 350% by mass or less, still more preferably 300% by mass or less, from the viewpoint of the amount of component (E) remaining in the electrode film.
  • the solid content of the conductive pigment (B) in the solid content of the composite material paste of the present invention is, for example, 0.01% by mass or more, preferably 0.05% by mass or more, and more preferably 0.1% by mass or more.
  • the content is preferably 30% by mass or less, preferably 20% by mass or less, more preferably 15% by mass or less.
  • the content of the solvent (C) in the composite material paste of the present invention is, for example, 1% by mass or more, preferably 5% by mass or more, more preferably 10% by mass or more, and, for example, 70% by mass or less, preferably From the viewpoint of electrode drying efficiency and paste viscosity, the content is preferably 60% by mass or less, more preferably 50% by mass or less.
  • the electrode composite material layer (also called electrode layer or composite material layer) of a lithium ion secondary battery is made by applying composite material paste for lithium ion battery electrodes to the surface of the core material of the positive or negative electrode. It can be manufactured by coating and drying, and the obtained electrode mixture layer of a lithium ion secondary battery is particularly preferably used as a positive electrode.
  • the conductive pigment paste of the present invention can be used not only as a paste for a composite layer but also as a primer layer between an electrode core material and a composite layer.
  • the method for applying the composite material paste for lithium ion battery electrodes can be performed by a method known per se using a die coater or the like.
  • the coating amount of the composite material paste for lithium ion battery electrodes is not particularly limited, but for example, the thickness of the composite material layer after drying is 0.04 mm or more, preferably 0.06 mm or more, and, for example, 0.30 mm or less, 0.04 mm or more. It can be set within a range of 24 mm or less.
  • the temperature of the drying step can be appropriately set within the range of, for example, 80 to 200°C, preferably 100 to 180°C.
  • the time for the drying step can be appropriately set, for example, within the range of 5 to 120 seconds, preferably 5 to 60 seconds.
  • a methanol solution of sodium hydroxide was added to carry out a saponification reaction, and the mixture was thoroughly washed and then dried with a hot air dryer. Finally, a sulfonic acid modified polyvinyl alcohol resin with a weight average molecular weight of 17000, a polar functional group concentration of 18.1 mmol / g, and a saponification degree of 90 mol% was obtained.
  • Example 1A 40 parts of sulfonic acid-modified polyvinyl alcohol resin (solid content: 40 parts) obtained in Production Example 1, 200 parts of carbon nanotubes (CNT1), KF Polymer W#7300 (trade name, polyvinylidene fluoride, weight average molecular weight 1 million, Kureha Co., Ltd.) 180 parts of N-methyl-2-pyrrolidone (NMP1), and 200 parts of benzylamine were mixed and dispersed in a ball mill for 5 hours to produce a conductive pigment paste (A-1).
  • CNT1 carbon nanotubes
  • KF Polymer W#7300 trade name, polyvinylidene fluoride, weight average molecular weight 1 million, Kureha Co., Ltd.
  • NMP1 N-methyl-2-pyrrolidone
  • Example 1B 100 parts of the conductive pigment paste (A-1) was mixed with 900 parts of active material particles (lithium nickel manganese oxide particles having a spinel structure represented by the composition formula LiNi0.5Mn1.5O4 , average particle size 6 ⁇ m , BET specific surface area 0.7 m2 /g) using a disperser to produce a composite paste (B-1).
  • active material particles lithium nickel manganese oxide particles having a spinel structure represented by the composition formula LiNi0.5Mn1.5O4 , average particle size 6 ⁇ m , BET specific surface area 0.7 m2 /g
  • Examples 2B to 21B, Comparative Examples 1B to 2B Mixed material pastes (B-2) to (B-23) were obtained in the same manner as in Example 1B, except for using the formulations shown in Table 1 below.
  • CNT1 to CNT6 are all multi-walled carbon nanotubes.
  • the median diameter (D50), G/D ratio, and acidic group amount in the above table were measured by the following method.
  • the median diameter (D50) was measured using a laser diffraction/scattering type particle size distribution measuring device "LA-960" (trade name, manufactured by Horiba, Ltd.) according to the following procedure.
  • CMCNa carboxymethyl cellulose sodium
  • CMCNa aqueous solution A solid content of 2.0 g of F10MC (trade name, manufactured by Nippon Paper Industries, Ltd., sodium carboxymethylcellulose) was added to 100 mL of distilled water, and the mixture was stirred and dissolved at room temperature for 24 hours or more to prepare an aqueous solution containing 2.0% by mass of CMCNa.
  • F10MC trade name, manufactured by Nippon Paper Industries, Ltd., sodium carboxymethylcellulose
  • the time set (irradiation time) was set to 40 seconds, the POW SET was set to 50%, and the START POW was set to 50% (output 50%), and the carbon nanotube water was homogenized by ultrasonic irradiation using auto power operation with a constant output power.
  • a dispersion liquid was prepared.
  • the ratio of dispersed particles of carbon nanotubes of 1 ⁇ m or less and the median diameter (D50) were measured according to the following method.
  • the optical model of the LS 13 320 universal liquid module is set to have carbon nanotubes with a refractive index of 1.520 and water with a refractive index of 1.333, and approximately 1.0 mL of a CMCNa aqueous solution is filled after the module has been cleaned.
  • the prepared aqueous carbon nanotube dispersion was measured using a particle size analyzer with relative concentration, which indicates the percentage of light scattered outside the beam by the particles.
  • the Raman spectrum of carbon nanotubes was measured using a Raman microscope "XploRA" (trade name, manufactured by Horiba, Ltd.) using a laser wavelength of 532 nm.
  • the G/D ratio is the G/D ratio of carbon nanotubes when the maximum peak intensity is G within the range of -1 to 1600 cm -1 and D is the maximum peak intensity within the range of 1310 cm -1 to 1350 cm -1 . did.
  • Evaluation tests were conducted on the conductive pigment pastes and composite material pastes obtained in the above Examples and Comparative Examples. As for the evaluation, D is a failure. If even one evaluation result is a failure, the evaluation of the conductive pigment paste is a failure. The evaluation results are shown in Table 1.
  • the dispersibility of the obtained conductive pigment paste was evaluated according to the following criteria using a tube gauge according to the dispersion test of JIS K-5600-2-5.
  • D Aggregates are visually confirmed. Dispersibility is very poor.
  • ⁇ Initial viscosity> The viscosity of the resulting composite paste was measured using a cone-and-plate viscometer "Mars 2" (trade name, manufactured by HAAKE) at a shear rate of 2.0 sec -1 , and evaluated according to the following criteria.
  • D Viscosity is 50 Pa ⁇ s or more.
  • A The viscosity increase rate (%) after storage is 10% or more and less than 20%.
  • B The viscosity increase rate (%) after storage is 20% or more and less than 50%.
  • C The viscosity increase rate (%) after storage is 50% or more and less than 200%.
  • D The viscosity increase rate (%) after storage is 200% or more (or gelation makes it impossible to measure).
  • ⁇ Volume resistivity (conductivity)> The conductive pigment pastes obtained in Examples 1A, 7A, 8A, and 9A were further measured for volume resistivity.
  • a 5% by mass solution of polyvinylidene fluoride manufactured by Kureha Co., Ltd., trade name "KF Polymer W#7300", solvent: N-methyl-2-pyrrolidone
  • the ratio of the mass of the conductive pigment (B) in the obtained conductive pigment paste to the total mass of the solid content of the pigment dispersion resin (A) and the solid content of KF Polymer W#7300 in the conductive pigment paste is 5:100.
  • the conductive pigment paste and KF Polymer W#7300 solution were weighed out and mixed for 2 minutes using an ultrasonic homogenizer to obtain a measurement sample.
  • a measurement sample was coated on a glass plate (2 mm x 100 mm x 150 mm) using a doctor blade method, and dried by heating at 80° C. for 60 minutes to form a coating film on the glass plate.
  • a resistivity meter "Loresta-GP MCP-T610" (trade name) was measured using an ASP probe "MCP-TP03P” (trade name, manufactured by Mitsubishi Chemical Analytech). , manufactured by Mitsubishi Chemical Analytech, Inc.), and the volume resistivity was calculated by multiplying the obtained resistance value by a resistivity correction factor (RCF) of 4.532 and the film thickness of the coating film.
  • RCF resistivity correction factor
  • A The volume resistivity is less than 7 ⁇ cm, and the conductivity is good.
  • B Volume resistivity is 7 ⁇ cm or more and less than 15 ⁇ cm, and conductivity is normal.
  • D Volume resistivity is 15 ⁇ cm or more, and conductivity is poor.

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Abstract

La présente invention aborde le problème de la fourniture d'une pâte pigmentaire électroconductrice et d'une pâte de mélange qui, même lorsqu'elles ont une concentration en pigment élevée, sont excellentes en termes de dispersibilité de pigment et de stabilité au stockage, et de la fourniture d'une électrode pour batteries au lithium-ion qui présente diverses excellentes performances. La pâte pigmentaire électroconductrice comprend une résine de dispersion de pigment (A), un pigment électroconducteur (B), un solvant (C), une résine fluorée (D), et un composant basique de faible masse moléculaire (E), la résine de dispersion de pigment (A) ayant au moins une sorte de groupes fonctionnels polaires et ayant une concentration des groupes fonctionnels polaires de 0,3-23 mmol/g, le pigment électroconducteur (B) comprenant des nanotubes de carbone (B1), et lorsque la teneur du composant basique de faible masse moléculaire (E) pour 100 parties en masse de la teneur des nanotubes de carbone (B1) est exprimée par α (parties en masse) et l'aire de surface spécifique BET des nanotubes de carbone (B1) est exprimée par β (m2/g), alors X=α/β×300 et X est 5 ou plus.
PCT/JP2023/033509 2022-09-19 2023-09-14 Pâte pigmentaire électroconductrice, pâte de mélange et électrode pour batteries au lithium-ion WO2024063003A1 (fr)

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Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2019208637A1 (fr) * 2018-04-26 2019-10-31 東洋インキＳｃホールディングス株式会社 Dispersion de nanotubes de carbone et utilisation associée
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