WO2024048354A1 - Carbon nanotube dispersion, slurry composition for nonaqueous secondary battery electrode, electrode for nonaqueous secondary battery, and nonaqueous secondary battery - Google Patents

Carbon nanotube dispersion, slurry composition for nonaqueous secondary battery electrode, electrode for nonaqueous secondary battery, and nonaqueous secondary battery Download PDF

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WO2024048354A1
WO2024048354A1 PCT/JP2023/030040 JP2023030040W WO2024048354A1 WO 2024048354 A1 WO2024048354 A1 WO 2024048354A1 JP 2023030040 W JP2023030040 W JP 2023030040W WO 2024048354 A1 WO2024048354 A1 WO 2024048354A1
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polymer
secondary battery
mass
electrode
carbon nanotube
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Japanese (ja)
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翼 宮前
ジー・ボー
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日本ゼオン株式会社
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    • 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
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
    • C08F220/00—Copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and only one being terminated by only one carboxyl radical or a salt, anhydride ester, amide, imide or nitrile thereof
    • C08F220/02—Monocarboxylic acids having less than ten carbon atoms; Derivatives thereof
    • C08F220/42—Nitriles
    • C08F220/44—Acrylonitrile
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
    • C08F236/00—Copolymers of compounds having one or more unsaturated aliphatic radicals, at least one having two or more carbon-to-carbon double bonds
    • C08F236/02—Copolymers of compounds having one or more unsaturated aliphatic radicals, at least one having two or more carbon-to-carbon double bonds the radical having only two carbon-to-carbon double bonds
    • C08F236/04—Copolymers of compounds having one or more unsaturated aliphatic radicals, at least one having two or more carbon-to-carbon double bonds the radical having only two carbon-to-carbon double bonds conjugated
    • C08F236/12—Copolymers of compounds having one or more unsaturated aliphatic radicals, at least one having two or more carbon-to-carbon double bonds the radical having only two carbon-to-carbon double bonds conjugated with nitriles
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K3/00—Use of inorganic substances as compounding ingredients
    • C08K3/02—Elements
    • C08K3/04—Carbon
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K7/00—Use of ingredients characterised by shape
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L33/00—Compositions of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and only one being terminated by only one carboxyl radical, or of salts, anhydrides, esters, amides, imides or nitriles thereof; Compositions of derivatives of such polymers
    • C08L33/18—Homopolymers or copolymers of nitriles
    • C08L33/20—Homopolymers or copolymers of acrylonitrile
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L9/00—Compositions of homopolymers or copolymers of conjugated diene hydrocarbons
    • C08L9/02—Copolymers with acrylonitrile
    • 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
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Definitions

  • the present invention relates to a carbon nanotube dispersion, a slurry composition for a non-aqueous secondary battery electrode, an electrode for a non-aqueous secondary battery, and a non-aqueous secondary battery.
  • Non-aqueous secondary batteries such as lithium-ion secondary batteries have the characteristics of being small, lightweight, and have high energy density, and can be repeatedly charged and discharged. , used in a wide range of applications. Therefore, in recent years, improvements in battery components such as electrodes have been studied with the aim of further improving the performance of non-aqueous secondary batteries.
  • an electrode for a non-aqueous secondary battery usually includes a current collector and an electrode mixture layer formed on the current collector.
  • the electrode composite material layer is formed using, for example, a slurry composition in which an electrode active material, a polymer as a binder, a conductive material, and the like are dispersed in a dispersion medium.
  • carbon nanotubes (hereinafter sometimes abbreviated as "CNT”) can be suitably used as a conductive material in the slurry composition used to form the electrode composite material layer.
  • CNT carbon nanotubes
  • a carbon nanotube dispersion liquid is prepared in advance by mixing carbon nanotubes, a polymer as a binder, and a dispersion medium, and the obtained carbon nanotube dispersion liquid is
  • a slurry composition may be prepared by mixing the electrode active material and the like.
  • the carbon nanotube dispersion liquid prepared before the preparation of the slurry composition is required to have excellent dispersibility of carbon nanotubes.
  • an object of the present invention is to provide a carbon nanotube dispersion liquid with excellent dispersibility of carbon nanotubes. Another object of the present invention is to provide a slurry composition for a nonaqueous secondary battery electrode prepared using the carbon nanotube dispersion. Furthermore, an object of the present invention is to provide an electrode for a non-aqueous secondary battery including an electrode mixture layer formed using the slurry composition for a non-aqueous secondary battery electrode. And, an object of the present invention is to provide a non-aqueous secondary battery including the electrode for a non-aqueous secondary battery.
  • the present inventor conducted extensive studies in order to achieve the above object.
  • the present inventor also found that a carbon nanotube dispersion containing carbon nanotubes and a predetermined polymer and having a rate of change in specific absorbance before and after centrifugation treatment that is less than a predetermined value has excellent dispersibility of carbon nanotubes.
  • the present invention was completed based on the discovery that
  • an object of the present invention is to advantageously solve the above problems, and the present invention provides [1] a carbon nanotube dispersion containing carbon nanotubes, a polymer, and a dispersion medium, which The aggregate contains a nitrile group-containing monomer unit, an alkylene structural unit, and a hydrophilic group-containing monomer unit, the specific absorbance of the carbon nanotube dispersion is set to E1, and the carbon nanotube dispersion is heated at 4000 rpm.
  • a polymer containing carbon nanotubes, a nitrile group-containing monomer unit, an alkylene structural unit, and a hydrophilic group-containing monomer unit has a specific absorbance change rate of a predetermined value before and after centrifugation treatment.
  • a carbon nanotube dispersion liquid having a carbon nanotube dispersion of less than 10% has excellent dispersibility of carbon nanotubes.
  • the "monomer unit" of a polymer means "a repeating unit derived from the monomer and contained in a polymer obtained using the monomer.” Furthermore, in the present invention, the specific absorbance E1 of the carbon nanotube dispersion, the specific absorbance E2 of the supernatant, and the rate of change ⁇ E in the specific absorbance before and after centrifugation are measured and calculated according to the method described in the Examples of this specification. be able to.
  • the weight average molecular weight of the polymer is 2,000 or more and 200,000 or less. If the weight average molecular weight of the polymer is within the above predetermined range, the adsorption amount of the polymer to CNTs will increase, further improving the dispersibility of CNTs in the CNT dispersion liquid, and improving the viscosity stability of the CNT dispersion liquid. can be improved. Furthermore, if the weight average molecular weight of the polymer is within the above-described range, the cycle characteristics and high-temperature storage characteristics of a secondary battery including an electrode composite layer formed using a slurry composition containing a CNT dispersion can be improved. be able to. Note that the weight average molecular weight of the polymer can be measured according to the method described in the Examples of this specification.
  • the haze of the 8% by mass aqueous solution of the polymer is 70% or less at pH 8.0 or higher. If the haze of the above-mentioned predetermined aqueous solution of the polymer is below the above-mentioned predetermined value, the adsorption amount of the polymer to CNTs will increase, which will further improve the dispersibility of CNTs in the CNT dispersion, and will also reduce the viscosity of the CNT dispersion. Stability can be improved.
  • the cycle characteristics and high-temperature storage characteristics of a secondary battery equipped with an electrode composite layer formed using a slurry composition containing a CNT dispersion can be improved.
  • the haze of an 8% by mass aqueous solution of the polymer can be measured according to the method described in the Examples of this specification.
  • the total content of alkylene structural units and conjugated diene monomer units in the polymer is 30% by mass or more and 80% by mass or less It is preferable that If the total content of alkylene structural units and conjugated diene monomer units in the polymer is within the above-mentioned predetermined range, the dispersibility of CNTs in the CNT dispersion can be further improved.
  • the content ratio of various repeating units (monomer units and structural units) in the polymer can be measured using a nuclear magnetic resonance (NMR) method such as 1 H-NMR.
  • the iodine value of the polymer is preferably 5 mg/100 mg or more and 100 mg/100 mg or less. If the iodine value of the polymer is within the above-mentioned predetermined range, the dispersibility of CNTs in the CNT dispersion can be further improved, and the viscosity stability of the CNT dispersion can be improved. Furthermore, if the iodine value of the polymer is within the above-mentioned predetermined range, the cycle characteristics and high-temperature storage characteristics of a secondary battery including an electrode composite layer formed using a slurry composition containing a CNT dispersion can be improved. Can be done. In addition, in this invention, the iodine value of a polymer can be measured according to the method described in the Example of this specification.
  • the content of the nitrile group-containing monomer unit in the polymer is preferably 10% by mass or more and 55% by mass or less. If the content of the nitrile group-containing monomer unit in the polymer is within the above-mentioned predetermined range, the dispersibility of CNTs in the CNT dispersion can be further improved.
  • the value of the volume average particle diameter D50 in the particle size distribution of the dispersed particle size of the carbon nanotubes is 0.1 ⁇ m or more and 15.0 ⁇ m or less. It is preferable that there be. If the volume average particle diameter of CNTs in the CNT dispersion liquid is within the above-mentioned predetermined range, the dispersibility of CNTs in the CNT dispersion liquid can be further improved. Note that the volume average particle diameter D50 of CNT can be measured according to the method described in Examples of this specification.
  • the content of hydrophilic group-containing monomer units in the polymer is 6.5% by mass or more and 50% by mass or less. It is preferable. If the content of the hydrophilic group-containing monomer unit in the polymer is within the above-determined range, the adsorption amount of the polymer to CNTs will increase, further improving the dispersibility of CNTs in the CNT dispersion, and , the viscosity stability of the CNT dispersion can be improved.
  • a secondary battery including an electrode composite layer formed using a slurry composition containing a CNT dispersion may be used. Cycle characteristics and high temperature storage characteristics can be improved.
  • the polymer does not contain a (meth)acrylic acid ester monomer unit. If a polymer containing no (meth)acrylic acid ester monomer unit is used, the dispersibility of CNTs in the CNT dispersion can be further improved.
  • (meth)acrylic means acrylic and/or methacryl.
  • the polymer does not contain aromatic vinyl monomer units.
  • the dispersibility of CNTs in the CNT dispersion can be further improved.
  • a slurry composition for a non-aqueous secondary battery electrode comprising: In this way, a slurry composition for a non-aqueous secondary battery electrode containing any of the above-mentioned CNT dispersions allows a secondary battery to exhibit excellent battery characteristics (such as cycle characteristics and high-temperature storage characteristics). An electrode having the electrode composite material layer obtained can be formed.
  • the present invention aims to advantageously solve the above problems, and the present invention provides an electrode formed using the slurry composition for non-aqueous secondary battery electrodes according to [12] above [11].
  • This is an electrode for a non-aqueous secondary battery that includes a composite material layer.
  • a non-aqueous secondary battery electrode with excellent battery characteristics such as cycle characteristics and high-temperature storage characteristics can be used.
  • a secondary battery can be stably obtained.
  • the present invention also provides a non-aqueous secondary battery comprising the electrode for a non-aqueous secondary battery according to [12] above. be.
  • a non-aqueous secondary battery comprising the electrode for a non-aqueous secondary battery according to [12] above. be.
  • a carbon nanotube dispersion liquid with excellent dispersibility of carbon nanotubes it is possible to provide a slurry composition for a non-aqueous secondary battery electrode prepared using the carbon nanotube dispersion. Further, according to the present invention, it is possible to provide an electrode for a non-aqueous secondary battery formed using the slurry composition for a non-aqueous secondary battery electrode. Furthermore, according to the present invention, a non-aqueous secondary battery including the non-aqueous secondary battery electrode can be provided.
  • the CNT dispersion of the present invention can be used for preparing the slurry composition for non-aqueous secondary battery electrodes of the present invention (hereinafter sometimes simply referred to as "slurry composition").
  • the slurry composition for a non-aqueous secondary battery electrode of the present invention can be used when manufacturing an electrode for a non-aqueous secondary battery such as a lithium ion secondary battery.
  • the non-aqueous secondary battery of the present invention includes an electrode for a non-aqueous secondary battery of the present invention (hereinafter simply referred to as "electrode”) formed using the slurry composition for a non-aqueous secondary battery electrode of the present invention. ).
  • the CNT dispersion liquid of the present invention contains CNTs, a predetermined polymer, and a dispersion medium, and is characterized in that the rate of change in specific absorbance before and after a predetermined centrifugal treatment is less than a predetermined value.
  • the CNT dispersion liquid of the present invention has excellent CNT dispersibility. Therefore, according to the slurry composition prepared using the CNT dispersion of the present invention, an electrode mixture layer that can exhibit excellent battery characteristics (e.g., cycle characteristics, high-temperature storage characteristics, etc.) in a secondary battery can be formed. be able to.
  • the CNT dispersion of the present invention may further contain components (other components) other than the above-mentioned CNTs, a predetermined polymer, and a dispersion medium, but usually does not contain an electrode active material.
  • the rate of change in specific absorbance ⁇ E is preferably 40% or less, more preferably 35% or less, even more preferably 30% or less, even more preferably 25% or less, It is even more preferable that it is 23% or less. If the rate of change in specific absorbance ⁇ E is below the above upper limit, the dispersibility of CNTs in the CNT dispersion can be further improved. Further, the lower limit of the rate of change in specific absorbance ⁇ E is not particularly limited, and may be, for example, 0% or more, 1% or more, or 5% or more.
  • the value of the rate of change in specific absorbance ⁇ E is controlled, for example, by the composition and properties of the polymer contained in the CNT dispersion, the conditions of the dispersion processing machine and dispersion treatment during the production of the CNT dispersion, etc. be able to.
  • CNT is a material that can function as a conductive material that promotes electrical contact between electrode active materials in an electrode composite material layer formed using a slurry composition containing a CNT dispersion.
  • the average diameter of the CNTs is preferably 3 nm or more and 20 nm or less. If the average diameter of the CNTs is within the above-mentioned predetermined range, the dispersibility of the CNTs can be ensured to be sufficiently high.
  • the average length of the CNTs is preferably 5 ⁇ m or more and 30 ⁇ m or less. If the average length of the CNTs is within the above predetermined range, the dispersibility of the CNTs can be ensured sufficiently high while a secondary battery including an electrode mixture layer formed using a slurry composition containing a CNT dispersion liquid can be produced. Cycle characteristics can be improved.
  • the average diameter and average length of CNTs are determined by randomly selecting 100 CNTs from images obtained by observation using a scanning electron microscope (SEM). It can be measured by measuring the diameter and finding the average value of the diameter (outer diameter) and length of the 100 CNTs.
  • SEM scanning electron microscope
  • the BET specific surface area of the CNT is preferably 100 m 2 /g or more, more preferably 150 m 2 /g or more, and usually 2500 m 2 /g or less. If the BET specific surface area of the CNT is equal to or larger than the above-mentioned lower limit, interaction with the polymer will occur favorably, and the high-temperature storage characteristics of the obtained secondary battery can be improved. Thereby, a good conductive path can be formed in the electrode mixture layer, and the output characteristics of the secondary battery can be improved. Further, if the BET specific surface area of the CNTs is below the above upper limit, aggregation of the CNTs can be suppressed and a sufficiently high dispersibility of the CNTs can be ensured.
  • CNTs tend to aggregate and are difficult to disperse.
  • the rate of change in specific absorbance before and after the above-mentioned centrifugation treatment is less than the predetermined value, CNTs can be dispersed well and stably.
  • the polymer is a component capable of favorably dispersing CNTs as a conductive material in a CNT dispersion liquid. Further, the polymer is a component that can also exhibit the function of holding components contained in the electrode composite material layer so that they do not separate from the electrode composite material layer.
  • the polymer needs to contain a nitrile group-containing monomer unit, an alkylene structural unit, and a hydrophilic group-containing monomer. Furthermore, the polymer may optionally further contain repeating units other than the nitrile group-containing monomer unit, the alkylene structural unit, and the hydrophilic group-containing monomer unit.
  • the nitrile group-containing monomer unit is a repeating unit derived from a nitrile group-containing monomer unit.
  • Examples of the nitrile group-containing monomer that can form the nitrile group-containing monomer unit include ⁇ , ⁇ -ethylenically unsaturated nitrile monomers.
  • the ⁇ , ⁇ -ethylenically unsaturated nitrile monomer is not particularly limited as long as it is an ⁇ , ⁇ -ethylenically unsaturated compound having a nitrile group, but examples include acrylonitrile; ⁇ -chloroacrylonitrile, ⁇ -bromo Examples thereof include ⁇ -halogenoacrylonitrile such as acrylonitrile; ⁇ -alkylacrylonitrile such as methacrylonitrile and ⁇ -ethyl acrylonitrile; and the like.
  • acrylonitrile and methacrylonitrile are preferred, and acrylonitrile is more preferred. These can be used alone or in combination of two or more.
  • the content of the nitrile group-containing monomer unit in the polymer is 10% by mass or more when the total repeating units (the sum of structural units and monomer units) in the polymer are 100% by mass. It is preferably 20% by mass or more, more preferably 25% by mass or more, even more preferably 30% by mass or more, preferably 55% by mass or less, 40% by mass or more. It is more preferable that it is less than % by mass. If the content of the nitrile group-containing monomer unit in the polymer is within the above-mentioned predetermined range, the dispersibility of CNTs in the CNT dispersion can be further improved.
  • alkylene structural unit is a repeating unit composed only of an alkylene structure represented by the general formula: -C n H 2n - [where n is an integer of 2 or more].
  • n is an integer of 2 or more.
  • the alkylene structural unit may be linear or branched, but from the viewpoint of further improving the dispersibility of CNTs in the CNT dispersion, the alkylene structural unit is linear, that is, a linear alkylene structure. Preferably, it is a unit. Further, the number of carbon atoms in the alkylene structural unit is preferably 4 or more (that is, n in the above-mentioned general formula -C n H 2n - is an integer of 4 or more).
  • the method of introducing the alkylene structural unit into the polymer is not particularly limited, but for example, the following method (1) or (2): (1) A method of converting conjugated diene monomer units into alkylene structural units by preparing a polymer from a monomer composition containing a conjugated diene monomer and hydrogenating (hydrogenating) the polymer. (2) A method of preparing a polymer from a monomer composition containing a 1-olefin monomer can be mentioned. Among these, method (1) is preferred because it allows easy production of the polymer.
  • the alkylene structural unit is preferably a structural unit (conjugated diene hydride unit) obtained by hydrogenating a conjugated diene monomer unit, and is preferably a structural unit obtained by hydrogenating a 1,3-butadiene unit.
  • the structural unit (1,3-butadiene hydride unit) is more preferable.
  • Examples of the 1-olefin monomer include 1-butene and 1-hexene. These conjugated diene monomers and 1-olefin monomers can be used alone or in combination of two or more.
  • the conjugated diene monomers that can be used in the method (1) above include, for example, conjugated dienes such as 1,3-butadiene, isoprene, 2,3-dimethyl-1,3-butadiene, and 1,3-pentadiene. Examples include compounds. Among them, 1,3-butadiene is preferred. That is, the alkylene structural unit is preferably a structural unit obtained by hydrogenating a conjugated diene monomer unit (conjugated diene hydride unit), and a structural unit obtained by hydrogenating a 1,3-butadiene unit (1 , 3-butadiene hydride unit). The hydrogenation can be carried out using a known method as described below.
  • conjugated dienes such as 1,3-butadiene, isoprene, 2,3-dimethyl-1,3-butadiene, and 1,3-pentadiene. Examples include compounds. Among them, 1,3-butadiene is preferred. That is, the alkylene structural unit is preferably
  • the alkylene structural unit when the alkylene structural unit is introduced into the polymer through the method (1) above, if the conjugated diene monomer unit is not completely hydrogenated, the conjugated diene monomer unit will not be completely hydrogenated in the polymer. Units may remain. In other words, the polymer may optionally contain conjugated diene monomer units as repeating units.
  • the total content of alkylene structural units and conjugated diene monomer units in the polymer is 30% by mass when all repeating units (total of structural units and monomer units) in the polymer are 100% by mass. % or more, more preferably 50% by mass or more, even more preferably 55% by mass or more, even more preferably 60% by mass or more, and preferably 80% by mass or less. , more preferably 75% by mass or less, and even more preferably 70% by mass or less. If the total content of alkylene structural units and conjugated diene monomer units in the polymer is within the above-mentioned predetermined range, the dispersibility of CNTs in the CNT dispersion can be further improved.
  • the content of alkylene structural units in the polymer is 30% by mass or more when the total repeating units (total of structural units and monomer units) in the polymer is 100% by mass. It is preferably 50% by mass or more, more preferably 60% by mass or more, preferably 80% by mass or less, more preferably 75% by mass or less, and 70% by mass or less. It is more preferably less than % by mass. If the content ratio of alkylene structural units in the polymer is within the above-mentioned predetermined range, the dispersibility of CNTs in the CNT dispersion can be further improved.
  • hydrophilic group-containing monomer unit is a repeating unit derived from a hydrophilic group-containing monomer.
  • Hydrophilic group-containing monomers that can form hydrophilic group-containing monomer units include monomers having a carboxylic acid group, monomers having a sulfonic acid group, monomers having a phosphoric acid group, and monomers having a hydroxyl group. Examples include monomers having the following.
  • Examples of the monomer having a carboxylic acid group include monocarboxylic acids and derivatives thereof, dicarboxylic acids and anhydrides thereof, and derivatives thereof.
  • Examples of monocarboxylic acids include acrylic acid, methacrylic acid, and crotonic acid.
  • Examples of monocarboxylic acid derivatives include 2-ethyl acrylic acid, isocrotonic acid, ⁇ -acetoxyacrylic acid, ⁇ -trans-aryloxyacrylic acid, ⁇ -chloro- ⁇ -E-methoxyacrylic acid, ⁇ -diaminoacrylic acid, etc.
  • Examples of dicarboxylic acids include maleic acid, fumaric acid, and itaconic acid.
  • dicarboxylic acid derivatives include methylmaleic acid, dimethylmaleic acid, phenylmaleic acid, chloromaleic acid, dichloromaleic acid, fluoromaleic acid, methylallyl maleate, diphenyl maleate, nonyl maleate, decyl maleate, and dodecyl maleate. , octadecyl maleate, fluoroalkyl maleate, and other maleic acid esters.
  • acid anhydrides of dicarboxylic acids include maleic anhydride, acrylic anhydride, methylmaleic anhydride, dimethylmaleic anhydride, and the like.
  • an acid anhydride that generates a carboxyl group by hydrolysis can also be used.
  • monoesters and diesters of ⁇ , ⁇ -ethylenically unsaturated polycarboxylic acids such as monobutyl itaconate, dibutyl itaconate, and the like.
  • Examples of monomers having a sulfonic acid group include vinylsulfonic acid, methylvinylsulfonic acid, (meth)allylsulfonic acid, styrenesulfonic acid, ethyl (meth)acrylate-2-sulfonate, and 2-acrylamide-2-methyl.
  • Examples include propanesulfonic acid and 3-allyloxy-2-hydroxypropanesulfonic acid.
  • (meth)allyl means allyl and/or methallyl.
  • Monomers having a phosphoric acid group include 2-(meth)acryloyloxyethyl phosphate, methyl-2-(meth)acryloyloxyethyl phosphate, ethyl-(meth)acryloyloxyethyl phosphate, and vinylphosphonic acid. , dimethyl vinylphosphonate, and the like.
  • (meth)acryloyl means acryloyl and/or methacryloyl.
  • Examples of monomers having a hydroxyl group include ethylenically unsaturated alcohols such as (meth)allyl alcohol, 3-buten-1-ol, and 5-hexen-1-ol; 2-hydroxyethyl acrylate, and 2-hydroxyethyl acrylate; -Ethylenic compounds such as hydroxypropyl, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, di-2-hydroxyethyl maleate, di-4-hydroxybutyl maleate, di-2-hydroxypropyl itaconate, etc.
  • ethylenically unsaturated alcohols such as (meth)allyl alcohol, 3-buten-1-ol, and 5-hexen-1-ol
  • 2-hydroxyethyl acrylate 2-hydroxyethyl acrylate
  • 2-hydroxyethyl acrylate 2-hydroxyethyl acrylate
  • -Ethylenic compounds such as hydroxypropyl, 2-hydroxyethyl methacrylate
  • a monomer having a carboxylic acid group (carboxylic acid group-containing monomer) as the hydrophilic group-containing monomer.
  • monocarboxylic acid it is more preferable to use monocarboxylic acid, and even more preferable to use methacrylic acid.
  • the content ratio of the hydrophilic group-containing monomer unit in the polymer is 6.5% by mass when the total repeating units (total of structural units and monomer units) in the polymer are 100% by mass. It is preferably at least 8% by mass, more preferably at least 9% by mass, even more preferably at least 10% by mass, and preferably at most 50% by mass, It is more preferably 35% by mass or less, even more preferably 25% by mass or less, and even more preferably 15% by mass or less. If the content of hydrophilic group-containing monomer units in the polymer is equal to or higher than the above lower limit, sufficient hydrophilic groups, which are polar groups, will be introduced into the polymer, and the movement of the molecular chains of the polymer will be inhibited.
  • the polymer becomes flexible, but the amount of adsorption of the polymer onto the CNTs increases, making it possible to further improve the dispersibility of the CNTs in the CNT dispersion.
  • the content ratio of the hydrophilic group-containing monomer unit in the polymer is equal to or higher than the above lower limit, the polymer will remain in the electrode composite material layer formed from the slurry composition prepared using the CNT dispersion. This is presumably because capturing moisture makes it difficult for the charging/discharging function to be inhibited by moisture, and it is possible to improve the cycle characteristics and high-temperature storage characteristics of the secondary battery.
  • the content of the hydrophilic group-containing monomer unit in the polymer is below the above upper limit, it is possible to further improve the dispersibility of CNTs in the CNT dispersion and to improve the viscosity stability of the CNT dispersion. can.
  • the content of the hydrophilic group-containing monomer unit in the polymer is below the above upper limit, the adhesion of the electrode composite layer formed from the slurry composition prepared using the CNT dispersion can be improved, and , the high-temperature storage characteristics of a secondary battery including the electrode mixture layer can be improved.
  • the polymer contains monomer units other than the above-mentioned nitrile group-containing monomer units, alkylene structural units, conjugated diene monomer units, and hydrophilic group-containing monomer units (hereinafter referred to as “other monomer units”) as repeating units. (referred to as "monomeric units").
  • the content ratio of other monomer units in the polymer shall be 5% by mass or less, when the total repeating units (total of structural units and monomer units) in the polymer are 100% by mass. It is preferably at most 4% by mass, more preferably at most 3% by mass, even more preferably at most 2% by mass, even more preferably at most 1% by mass. If the content of other monomer units in the polymer is below the above upper limit, the adsorption amount of the polymer to CNTs will increase, further improving the dispersibility of CNTs in the CNT dispersion, and improving the CNT dispersion.
  • the lower limit of the content of other monomer units in the polymer is not particularly limited, and can be, for example, 0% by mass or more. From the viewpoint of further improving the dispersibility of CNTs in the CNT dispersion, the content of other monomer units in the polymer is particularly preferably 0% by mass. That is, it is particularly preferable that the polymer contains no monomer units other than nitrile group-containing monomer units, alkylene structural units, conjugated diene monomer units, and hydrophilic group-containing monomer units.
  • Monomers that can form other monomer units are not particularly limited, and examples thereof include (meth)acrylic acid ester monomers and aromatic vinyl monomers. In addition, these monomers can be used individually or in combination of two or more types.
  • the (meth)acrylic acid ester monomer unit is a repeating unit derived from a (meth)acrylic acid ester monomer.
  • the (meth)acrylic acid ester monomer methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, t-butyl acrylate, isobutyl acrylate, n-pentyl acrylate, isopentyl acrylate , hexyl acrylate, heptyl acrylate, octyl acrylate, 2-ethylhexyl acrylate, nonyl acrylate, decyl acrylate, lauryl acrylate, n-tetradecyl acrylate, stearyl acrylate, and other acrylic acid alkyl esters; methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, Isopropyl methacrylate, n-butyl methacrylate, t-butyl methacrylate,
  • the content ratio of (meth)acrylic acid ester monomer units in the polymer is 5% by mass when the total repeating units (total of structural units and monomer units) in the polymer is 100% by mass. It is preferably at most 4% by mass, more preferably at most 3% by mass, even more preferably at most 2% by mass, even more preferably at most 1% by mass. preferable. If the content of (meth)acrylic acid ester monomer units in the polymer is below the above upper limit, the adsorption amount of the polymer to CNTs will increase, further improving the dispersibility of CNTs in the CNT dispersion, and , the viscosity stability of the CNT dispersion can be improved.
  • the adhesiveness of the electrode composite layer formed from the slurry composition prepared using the CNT dispersion may be reduced. can be increased.
  • the content of (meth)acrylic acid ester monomer units in the polymer is below the above upper limit, the cycle characteristics and high-temperature storage characteristics of the secondary battery including the electrode composite layer can be improved.
  • the lower limit of the content of (meth)acrylic acid ester monomer units in the polymer is not particularly limited, and can be, for example, 0% by mass or more.
  • the content of (meth)acrylic acid ester monomer units in the polymer is particularly preferably 0% by mass. That is, it is particularly preferable that the polymer does not contain (meth)acrylic acid ester monomer units.
  • Aromatic vinyl monomer units are repeating units derived from aromatic vinyl monomers.
  • examples of the aromatic vinyl monomer that can form aromatic vinyl monomer units include styrene, ⁇ -methylstyrene, vinyltoluene, divinylbenzene, and the like. These can be used alone or in combination of two or more.
  • the content ratio of aromatic vinyl monomer units in the polymer is 5% by mass or less when the total repeating units (total of structural units and monomer units) in the polymer are 100% by mass. It is preferably at most 4% by mass, more preferably at most 3% by mass, even more preferably at most 2% by mass, and even more preferably at most 1% by mass. If the content of aromatic vinyl monomer units in the polymer is below the above upper limit, the adsorption amount of the polymer to CNTs will increase, further improving the dispersibility of CNTs in the CNT dispersion liquid, and improving CNT dispersion. The viscosity stability of the liquid can be improved.
  • the content of aromatic vinyl monomer units in the polymer is below the above upper limit, it is possible to improve the adhesion of the electrode composite layer formed from the slurry composition prepared using the CNT dispersion. can. Furthermore, if the content of the aromatic vinyl monomer unit in the polymer is below the above upper limit, the cycle characteristics and high temperature storage characteristics of the secondary battery including the electrode composite layer can be improved.
  • the lower limit of the content of aromatic vinyl monomer units in the polymer is not particularly limited, and can be, for example, 0% by mass or more. From the viewpoint of further improving the dispersibility of CNTs in the CNT dispersion, the content of aromatic vinyl monomer units in the polymer is particularly preferably 0% by mass. That is, it is particularly preferable that the polymer does not contain aromatic vinyl monomer units.
  • the method for producing the above-described polymer is not particularly limited, and any method such as solution polymerization, suspension polymerization, bulk polymerization, emulsion polymerization, etc. can be used. Further, as the polymerization method, addition polymerization such as ionic polymerization, radical polymerization, and living radical polymerization can be used. Furthermore, known polymerization initiators can be used as the polymerization initiator.
  • a molecular weight regulator having a sulfur-containing group such as a mercapto group.
  • compounds having a mercapto group as molecular weight regulators include octylmercaptan, 2,2,4,6,6-pentamethyl-4-heptanethiol, 2,4,4,6,6-pentamethyl-2- Carbon atoms such as heptanethiol, 2,3,4,6,6-pentamethyl-2-heptanethiol, 2,3,4,6,6-pentamethyl-3-heptanethiol, t-dodecylmercaptan, n-dodecylmercaptan, etc.
  • Compounds having 8 to 12 mercapto groups 2,2,4,6,6-pentamethyl-4-octanethiol, 2,2,4,6,6,8,8-heptamethyl-4-nonanethiol, bis Examples include compounds having a mercapto group such as (2-mercaptoethyl) sulfide, methyl 3-mercaptopropionate, and 1-butanethiol. Among these, compounds having a mercapto group having 8 to 12 carbon atoms are preferred, and t-dodecylmercaptan is more preferred.
  • the amount of the compound having a mercapto group as a molecular weight regulator is preferably adjusted as appropriate so that the haze of the resulting 8% by mass aqueous solution (pH 8.0 or higher) of the polymer is equal to or less than a predetermined value described below. be able to.
  • radical polymerization using a redox polymerization initiator containing an iron-based compound may be used as the polymerization method for the polymer to be hydrogenated.
  • the redox polymerization initiator is not particularly limited, and includes, for example, cumene hydroperoxide, monosodium iron ethylenediaminetetraacetate, sodium hydroxymethanesulfinate, and tetrasodium ethylenediaminetetraacetic acid salt (EDTA.4Na). A combination of these can be used.
  • a coagulant is added to the obtained aqueous dispersion of the polymer (i.e., the precursor of the polymer) before hydrogenation.
  • the structure of the resulting hydrogenated polymer is maintained well. This is presumed to be because the haze of an 8% by mass aqueous solution (pH 8.0 or higher) of the polymer can be easily adjusted to a predetermined value or less, which will be described later, and the CNT dispersion prepared using the polymer. The dispersibility of CNTs therein can be further improved.
  • hydrogenation can be performed using a known hydrogenation method such as an oil layer hydrogenation method or an aqueous layer hydrogenation method.
  • a known hydrogenation method such as an oil layer hydrogenation method or an aqueous layer hydrogenation method.
  • any known selective hydrogenation catalyst can be used without limitation, and palladium-based catalysts and rhodium-based catalysts can be used. Two or more of these may be used in combination.
  • hydrogenation of the polymer may be performed using the method described in, for example, Japanese Patent No. 4509792. Specifically, hydrogenation of the polymer may be performed after carrying out a metathesis reaction of the polymer in the presence of a catalyst and a co-olefin.
  • a catalyst and a co-olefin a known ruthenium-based catalyst can be used as a catalyst for the metathesis reaction.
  • a catalyst for metathesis reaction bis(tricyclohexylphosphine)benzylideneruthenium dichloride, 1,3-bis(2,4,6-trimethylphenyl)-2-(imidazolidinylidene)(dichlorophenylmethylene)(tricyclo It is preferred to use a Grubbs catalyst such as xylphosphine)ruthenium.
  • a Grubbs catalyst such as xylphosphine)ruthenium.
  • the coolefin olefins having 2 to 16 carbon atoms such as ethylene, isobutane, and 1-hexane can be used.
  • a known homogeneous hydrogenation catalyst such as a Wilkinson catalyst ((PPh 3 ) 3 RhCl) can be used.
  • the weight average molecular weight of the polymer is preferably 2,000 or more, more preferably 5,000 or more, even more preferably 10,000 or more, and even more preferably 15,000 or more. , is even more preferably 20,000 or more, particularly preferably 25,000 or more, preferably 200,000 or less, more preferably 170,000 or less, and 150,000 or less. It is more preferably 100,000 or less, even more preferably 50,000 or less, and particularly preferably 28,000 or less. If the weight average molecular weight is at least the above lower limit, the dispersibility of CNTs in the CNT dispersion can be further improved.
  • the weight average molecular weight of the polymer is below the above upper limit, the adsorption amount of the polymer to CNTs will increase, further improving the dispersibility of CNTs in the CNT dispersion, and improving the viscosity stability of the CNT dispersion. can be improved. Moreover, if the weight average molecular weight of a polymer is below the said upper limit, the adhesiveness of the electrode composite material layer formed from the slurry composition prepared using CNT dispersion liquid can be improved. Furthermore, if the weight average molecular weight of the polymer is below the above upper limit, the cycle characteristics and high temperature storage characteristics of the secondary battery including the electrode composite material layer can be improved.
  • the average molecular weight of the polymer can be controlled, for example, by adjusting the amount of a molecular weight regulator added during polymerization.
  • the haze of an 8% by mass aqueous solution of the polymer is preferably 70% or less, more preferably 68% or less, even more preferably 64% or less, and even more preferably 58% or less at pH 8.0 or higher. It is more preferably at most 50%, even more preferably at most 40%, particularly preferably at most 30%. If the haze of the above-mentioned predetermined aqueous solution of the polymer is below the above-mentioned upper limit, the adsorption amount of the polymer to CNTs will increase, which will further improve the dispersibility of CNTs in the CNT dispersion and stabilize the viscosity of the CNT dispersion. can improve sex.
  • the adhesiveness of the electrode composite material layer formed from the slurry composition prepared using the CNT dispersion liquid can be improved.
  • the haze of the above-mentioned predetermined aqueous solution of the polymer is below the above-mentioned upper limit, it is presumed that the polymer captures water in the electrode composite layer, making it difficult for the charge/discharge function to be inhibited by water.
  • the cycle characteristics and high temperature storage characteristics of the secondary battery can be improved.
  • the lower limit of the haze of the 8% by mass aqueous solution of the polymer is not particularly limited, but may be, for example, 0% or more, or 5% or more.
  • the haze of the above-mentioned predetermined aqueous solution of the polymer can be controlled by the composition of the polymer (the content ratio of various repeating units), the weight average molecular weight, and the conditions of the method for producing the polymer.
  • the iodine value of the polymer is preferably 5 mg/100 mg or more, more preferably 7 mg/100 mg or more, even more preferably 10 mg/100 mg or more, preferably 100 mg/100 mg or less, and 80 mg/100 mg or more. /100mg or less is more preferable, and even more preferably 70mg/100mg or less. If the iodine value of the polymer is at least the above lower limit, the dispersibility of CNTs in the CNT dispersion can be further improved.
  • the iodine value of the polymer is below the above upper limit, the adsorption amount of the polymer to CNTs will increase, further improving the dispersibility of CNTs in the CNT dispersion, and improving the viscosity stability of the CNT dispersion. can be done. Moreover, if the iodine value of the polymer is below the above upper limit, the adhesiveness of the electrode composite material layer formed from the slurry composition prepared using the CNT dispersion can be improved. Furthermore, if the iodine value of the polymer is below the above upper limit, the cycle characteristics and high temperature storage characteristics of the secondary battery including the electrode composite layer can be improved.
  • the iodine value of the polymer may be 50 mg/100 mg or less, 35 mg/100 mg or less, 25 mg/100 mg or less, or 15 mg/100 mg or less. good. Note that the iodine value of the polymer can be controlled based on, for example, the amount of hydrogenation catalyst used when hydrogenating the polymer.
  • the content of the polymer in the CNT dispersion is preferably 10 parts by mass or more, more preferably 15 parts by mass or more, and even more preferably 20 parts by mass or more, based on 100 parts by mass of CNTs. , is preferably 100 parts by mass or less, more preferably 50 parts by mass or less, and even more preferably 30 parts by mass or less. If the content of the polymer in the CNT dispersion liquid is within the above-mentioned predetermined range, the dispersibility of CNTs in the CNT dispersion liquid can be further improved.
  • the dispersion medium contained in the CNT dispersion is not particularly limited, and both water and organic solvents can be used.
  • the organic solvent include N-methylpyrrolidone (NMP), N,N-dimethylformamide, and acetone.
  • NMP N-methylpyrrolidone
  • NMP N-methylpyrrolidone
  • one type may be used individually, and two or more types may be mixed and used in arbitrary ratios.
  • the content of the dispersion medium in the CNT dispersion liquid is such that the solid content concentration of the CNT dispersion liquid is, for example, 1% by mass or more, preferably 2% by mass or more, more preferably 3% by mass or more, and, for example, 30% by mass.
  • the content can be adjusted to preferably 25% by mass or less, more preferably 20% by mass or less.
  • the CNT dispersion liquid of the present invention may contain components such as a reinforcing material, a leveling agent, a viscosity modifier, and an electrolyte additive in addition to the above components. These are not particularly limited as long as they do not affect the battery reaction, and known ones, such as those described in International Publication No. 2012/115096, can be used. Furthermore, these components may be used alone or in combination of two or more in any ratio.
  • the CNT dispersion liquid of the present invention may further contain a conductive material other than CNT.
  • conductive materials other than CNT include carbon black (e.g., acetylene black, Ketjen Black (registered trademark), furnace black, etc.), graphite, carbon fibers other than carbon nanotubes, carbon flakes, and other conductive carbon materials; Metal fibers, foil, etc. can be used. These can be used alone or in combination of two or more.
  • the CNT dispersion of the present invention preferably does not contain any conductive material other than CNTs.
  • the CNT dispersion of the present invention can be prepared by dispersing carbon nanotubes and dissolving or dispersing the above-mentioned polymer and any other components in a dispersion medium. More specifically, the CNT dispersion of the present invention can be prepared by mixing carbon nanotubes, the above-mentioned polymer, and any other components while performing a dispersion treatment. In addition, in the preparation of the CNT dispersion liquid, preliminary mixing may be performed as necessary before mixing while performing the above-mentioned dispersion treatment. Furthermore, the polymer used for preparing the CNT dispersion may be in the form of a solution or dispersion obtained by dissolving or dispersing it in a dispersion medium.
  • Mixing while performing dispersion treatment can be carried out using a dispersion machine such as a ball mill, sand mill, bead mill, pigment dispersion machine, crusher, ultrasonic dispersion machine, homogenizer, planetary mixer, thin film swirl type high-speed mixer, etc. It can be carried out.
  • a dispersion machine such as a ball mill, sand mill, bead mill, pigment dispersion machine, crusher, ultrasonic dispersion machine, homogenizer, planetary mixer, thin film swirl type high-speed mixer, etc. It can be carried out.
  • a dispersion machine such as a ball mill, sand mill, bead mill, pigment dispersion machine, crusher, ultrasonic dispersion machine, homogenizer, planetary mixer, thin film swirl type high-speed mixer, etc.
  • “Filmix (registered trademark)” manufactured by Primix Co., Ltd.
  • the model number of “Filmix (registered trademark)” is "30-L type", “40-L type”, “56-L type”, “56 type” depending on the manufacturing scale of CNT dispersion liquid.
  • "80 type”, "125 type”, “156 type”, “252 type”, etc. can be selected and used.
  • the dispersion conditions when carrying out the dispersion treatment using a thin film swirl type high-speed mixer such as "Filmix (registered trademark)" manufactured by Primix Co., Ltd. can be adjusted as appropriate within the range where the desired effect of the present invention can be obtained.
  • the circumferential speed of the turbine of a thin film swirling type high-speed mixer is preferably 5 m/s or more, more preferably 10 m/s or more, even more preferably 15 m/s or more, and even more preferably 50 m/s or less.
  • the speed is preferably at most 40 m/s, more preferably at most 30 m/s, even more preferably at most 30 m/s.
  • the circumferential speed of the turbine of the thin film swirl type high-speed mixer is equal to or higher than the above lower limit, the dispersibility of CNTs in the resulting CNT dispersion can be further improved.
  • the circumferential speed of the turbine of the thin film swirl type high-speed mixer is below the above upper limit, cutting of CNTs due to excessive load can be suppressed, and the electrode mixture layer formed using a slurry composition containing a CNT dispersion can be It is possible to ensure sufficiently high cycle characteristics of the secondary battery provided.
  • the processing time of the distributed processing is preferably 30 seconds or more, more preferably 60 seconds or more, even more preferably 80 seconds or more, even more preferably 100 seconds or more, and 300 seconds or more. It is preferably at most 250 seconds, more preferably at most 200 seconds, even more preferably at most 150 seconds. If the treatment time of the dispersion treatment is at least the above-mentioned lower limit, the dispersibility of CNTs in the resulting CNT dispersion can be further improved. On the other hand, if the treatment time of the dispersion treatment is less than the above upper limit, cutting of CNTs due to excessive load can be suppressed, and a secondary battery equipped with an electrode composite layer formed using a slurry composition containing a CNT dispersion liquid can be manufactured. Sufficiently high cycle characteristics can be ensured.
  • CNTs are well and stably dispersed in the form of fine particles.
  • the volume average particle diameter D50 of the CNTs in the CNT dispersion is preferably 0.1 ⁇ m or more, preferably 15.0 ⁇ m or less, more preferably 12.0 ⁇ m or less, and 10.0 ⁇ m or less. It is more preferable that the particle size is 7.5 ⁇ m or less. If the volume average particle diameter D50 of CNTs in the CNT dispersion liquid is within the above-described predetermined range, the dispersibility of CNTs in the CNT dispersion liquid can be further improved.
  • the slurry composition for a non-aqueous secondary battery electrode of the present invention contains an electrode active material and the above-described conductive material dispersion of the present invention. That is, the slurry composition for a non-aqueous secondary battery electrode of the present invention contains an electrode active material, CNTs as a conductive material, a polymer, and a solvent, and further contains any other components. .
  • the CNTs and polymer contained in the slurry composition for a non-aqueous secondary battery electrode of the present invention are derived from the CNT dispersion of the present invention, and their preferred abundance ratio is that of the CNTs of the present invention. It is the same as the dispersion liquid.
  • the electrode active material (positive electrode active material, negative electrode active material) to be added to the slurry composition is not particularly limited, and known electrode active materials can be used.
  • the slurry composition of the present invention may contain a positive electrode active material or a negative electrode active material as an electrode active material. That is, the slurry composition of the present invention may be a positive electrode slurry composition or a negative electrode slurry composition.
  • the positive electrode active material in case a non-aqueous secondary battery is a lithium ion secondary battery is demonstrated below as an example, this invention is not limited to the following example.
  • positive electrode active materials for lithium ion secondary batteries include, but are not limited to, lithium-containing cobalt oxide (LiCoO 2 ), lithium manganate (LiMn 2 O 4 ), and lithium-containing nickel oxide (LiNiO 2 ) .
  • Co-Ni-Mn lithium-containing composite oxide Co-Ni-Mn lithium-containing composite oxide, Ni-Mn-Al lithium-containing composite oxide, Ni-Co-Al lithium-containing composite oxide, olivine-type lithium iron phosphate (LiFePO 4 ), olivine type lithium manganese phosphate (LiMnPO 4 ), lithium-excess spinel compound represented by Li 1+x Mn 2-x O 4 (0 ⁇ X ⁇ 2), Li[Ni 0.17 Li 0.2 Co 0.07 Mn 0.56 ]O 2 , LiNi 0.5 Mn 1.5 O 4 , and other known positive electrode active materials.
  • the lithium-containing composite oxide of Co-Ni-Mn includes Li(Ni 0.6 Co 0.2 Mn 0.2 )O 2 and Li(Ni 0.5 Co 0.2 Mn 0.3 )O. 2 , Li(Ni 1/3 Co 1/3 Mn 1/3 ) O 2 and the like.
  • lithium-containing cobalt oxide (LiCoO 2 ), lithium-containing nickel oxide (LiNiO 2 ), and Co-Ni-Mn are used as positive electrode active materials.
  • lithium-containing composite oxide Li[Ni 0.17 Li 0.2 Co 0.07 Mn 0.56 ]O 2 or LiNi 0.5 Mn 1.5 O 4 , and Co-Ni-Mn It is more preferable to use a lithium-containing composite oxide.
  • the blending amount and particle size of the electrode active material are not particularly limited, and can be the same as those of conventionally used positive electrode active materials.
  • CNT dispersion As the CNT dispersion, the above-mentioned CNT dispersion of the present invention is used.
  • the content of CNT in the slurry composition is preferably 0.01 parts by mass or more and 20 parts by mass or less based on 100 parts by mass of the electrode active material. If the content of CNT in the slurry composition is equal to or higher than the above lower limit, electrical contact between electrode active materials can be promoted. Moreover, if the content of CNT in the slurry composition is below the above-mentioned upper limit, the coatability of the slurry composition can be improved.
  • the suitable content of the polymer in the slurry composition is explained in the range of the suitable content of the polymer for CNT mentioned above in the item ⁇ Polymer content>> and at the beginning of this paragraph. It may be within a suitable range derived from the CNT content for the electrode active material.
  • slurry composition of the present invention is a slurry composition for a positive electrode of a lithium ion secondary battery
  • a fluorine-containing polymer such as polyvinylidene fluoride (PVdF) may be used as a binder. It is preferable to use them together.
  • the slurry composition contains one or more types of binders in addition to the above-mentioned polymers
  • the total content of the one or more types of binders is 100 parts by mass, and the above-mentioned polymers are
  • the amount of coalescence can be 5 parts by weight or more and 50 parts by weight or less.
  • the content of the above-mentioned polymer in the slurry composition is equal to or higher than the lower limit, the high-temperature storage characteristics of the obtained secondary battery can be improved.
  • the content rate of the polymer mentioned above is below the said upper limit, the adhesiveness of an electrode composite material layer can be improved.
  • the slurry composition described above can be prepared by dissolving or dispersing each of the components described above in a solvent such as water and an organic solvent.
  • a solvent such as water and an organic solvent.
  • the organic solvent an organic solvent that can be used for the CNT dispersion liquid described above in the section of ⁇ Dispersion medium> can be used.
  • the electrode for a non-aqueous secondary battery of the present invention includes an electrode mixture layer formed using the slurry composition for a non-aqueous secondary battery electrode of the present invention. More specifically, the electrode of the present invention includes an electrode mixture layer formed using the slurry composition of the present invention on a current collector. That is, the electrode composite material layer contains at least an electrode active material, a polymer, and carbon nanotubes as a conductive material. In addition, each component contained in the electrode mixture layer was contained in the above slurry composition, and the preferable abundance ratio of each component is determined by the preferable abundance ratio of each component in the slurry composition. It is the same as the abundance ratio.
  • the electrode for non-aqueous secondary batteries of the present invention it is possible to form a secondary battery that has excellent battery characteristics such as cycle characteristics and high-temperature storage characteristics.
  • the electrode for a non-aqueous secondary battery of the present invention includes, for example, a step of applying the above-mentioned slurry composition onto a current collector (coating step) and drying the slurry composition applied onto the current collector. and a step (drying step) of forming an electrode mixture layer on the current collector.
  • the electrode for a non-aqueous secondary battery of the present invention can be prepared by drying and granulating the slurry composition described above to prepare composite particles, and using the composite particles to form an electrode mixture layer on a current collector. It can also be manufactured by
  • the method for applying the slurry composition onto the current collector is not particularly limited, and any known method can be used. Specifically, as a coating method, a doctor blade method, a dip method, a reverse roll method, a direct roll method, a gravure method, an extrusion method, a brush coating method, etc. can be used. At this time, the slurry composition for a non-aqueous secondary battery electrode may be applied to only one side of the current collector, or may be applied to both sides. The thickness of the slurry film on the current collector after coating and before drying can be appropriately set depending on the thickness of the electrode mixture layer obtained by drying.
  • the current collector to which the slurry composition is applied a material that has electrical conductivity and is electrochemically durable is used.
  • a current collector made of iron, copper, aluminum, nickel, stainless steel, titanium, tantalum, gold, platinum, etc. can be used.
  • aluminum foil is particularly preferred as the current collector used for the positive electrode. Note that the above-mentioned materials may be used alone or in combination of two or more in any ratio.
  • the method of drying the slurry composition on the current collector is not particularly limited and any known method can be used, such as drying with hot air, hot air, low humidity air, vacuum drying, irradiation with infrared rays, electron beams, etc.
  • An example is a drying method.
  • the electrode mixture layer may be subjected to pressure treatment using a mold press, a roll press, or the like.
  • the pressure treatment can improve the adhesion between the electrode composite material layer and the current collector.
  • the electrode composite material layer contains a curable polymer, it is preferable to harden the polymer after forming the electrode composite material layer.
  • the non-aqueous secondary battery of the present invention includes the above-described electrode for a non-aqueous secondary battery of the present invention.
  • the non-aqueous secondary battery of the present invention includes a positive electrode, a negative electrode, an electrolyte, and a separator, and the non-aqueous secondary battery electrode of the present invention is used as at least one of the positive electrode and the negative electrode. It is something. Since the non-aqueous secondary battery of the present invention includes the electrode for non-aqueous secondary batteries of the present invention, it has excellent battery characteristics such as cycle characteristics and high-temperature storage characteristics.
  • the positive electrode may be the electrode of the present invention
  • the negative electrode may be an electrode other than the electrode of the present invention
  • the positive electrode may be an electrode other than the electrode of the present invention
  • the negative electrode may be the electrode of the present invention.
  • the electrode of the invention may be used, or both the positive electrode and the negative electrode may be the electrode of the invention.
  • this invention is not limited to the following example.
  • Electrodes that do not correspond to the electrodes of the present invention are not particularly limited, and known electrodes can be used.
  • an organic electrolytic solution in which a supporting electrolyte is dissolved in an organic solvent is usually used.
  • the supporting electrolyte for example, lithium salt is used.
  • lithium salts include LiPF 6 , LiAsF 6 , LiBF 4 , LiSbF 6 , LiAlCl 4 , LiClO 4 , CF 3 SO 3 Li, C 4 F 9 SO 3 Li, CF 3 COOLi, (CF 3 CO) 2 NLi. , (CF 3 SO 2 ) 2 NLi, (C 2 F 5 SO 2 ) NLi, and the like.
  • LiPF 6 , LiClO 4 , and CF 3 SO 3 Li are preferred, and LiPF 6 is particularly preferred since they are easily soluble in solvents and exhibit a high degree of dissociation.
  • one type of electrolyte may be used alone, or two or more types may be used in combination in any ratio.
  • the lithium ion conductivity tends to increase as a supporting electrolyte with a higher degree of dissociation is used, so the lithium ion conductivity can be adjusted depending on the type of supporting electrolyte.
  • the organic solvent used in the electrolyte is not particularly limited as long as it can dissolve the supporting electrolyte, but examples include dimethyl carbonate (DMC), ethylene carbonate (EC), diethyl carbonate (DEC), propylene carbonate (PC), Carbonates such as butylene carbonate (BC) and methyl ethyl carbonate (EMC); Esters such as ⁇ -butyrolactone and methyl formate; Ethers such as 1,2-dimethoxyethane and tetrahydrofuran; Sulfur-containing compounds such as sulfolane and dimethyl sulfoxide etc. are preferably used. Alternatively, a mixture of these solvents may be used. Note that the concentration of the electrolyte in the electrolytic solution can be adjusted as appropriate.
  • the separator is not particularly limited, and for example, those described in JP-A No. 2012-204303 can be used. Among these, polyolefin-based ( A microporous membrane made of a resin such as polyethylene, polypropylene, or polybutene is preferred.
  • the separator may be a separator with an adhesive layer formed by forming an adhesive layer (i.e., adhesive layer) on the surface of the microporous membrane, or a separator with an adhesive layer formed on the surface of the microporous membrane, or a separator with an adhesive layer formed on the surface of the microporous membrane.
  • a separator with a heat-resistant layer may also be used.
  • a positive electrode and a negative electrode are stacked on top of each other with a separator interposed therebetween, and this is rolled or folded according to the shape of the battery as necessary, and placed in a battery container, and the battery is electrolyzed in the battery container. It can be manufactured by injecting a liquid and sealing it.
  • a fuse, an overcurrent prevention element such as a PTC element, an expanded metal, a lead plate, etc. may be provided as necessary.
  • the shape of the secondary battery may be, for example, a coin shape, a button shape, a sheet shape, a cylindrical shape, a square shape, a flat shape, or the like.
  • the polymer is a hydrogenated polymer obtained by hydrogenating (hydrogenating) a polymer containing conjugated diene monomer units
  • unhydrogenated conjugated diene monomer in the hydrogenated polymer The total content ratio of the unit and the alkylene structural unit as a hydrogenated conjugated diene monomer unit is the ratio of the conjugated diene monomer to the total monomers used for polymerization of the polymer (preparation ratio) matches.
  • various measurements and evaluations were performed using the following methods.
  • Mw weight average molecular weight
  • Detector Differential refractometer detector RID-10A (manufactured by Shimadzu Corporation)
  • Flow rate of eluent 0.3 mL/min
  • Cold temperature 40°C
  • Standard polymer TSK standard polystyrene (manufactured by Tosoh Corporation)
  • the above-mentioned "0.8 mass% NMP solution of polymer” is a binder composition (8 mass% of polymer Aqueous solution) was diluted with NMP and the polymer concentration was adjusted to 0.8% by mass.
  • the above-mentioned "0.8 mass% NMP solution of polymer” is obtained by subjecting the CNT dispersion to necessary treatments such as centrifugation and filtration with a membrane filter to remove CNTs from the CNT dispersion.
  • the obtained liquid may be concentrated or diluted with NMP as necessary to adjust the solid content concentration to 0.8% by mass, and the obtained liquid may also be used.
  • the absorbance of the CNT dispersion for measurement was measured by ultraviolet-visible spectroscopy (Uv-Vis), and was defined as absorbance A (0.06) at a deemed concentration of 0.06 mg/mL. Note that the absorbance was measured under the following conditions.
  • Ultraviolet/visible spectrophotometer “V-750” manufactured by Jasco Uv-Vis measurement software: Jasco Spectrum Manager Sample container: Quartz cell (light path length 10 mm)
  • a 0.8% by mass NMP solution of the above polymer was added to the CNT dispersion for measurement prepared above (solid content concentration: 0.05% by mass) and diluted to 2 times by volume. A CNT dispersion liquid for measurement after dilution was obtained.
  • the mass-to-volume ratio concentration of the CNT dispersion for measurement after dilution was considered to be 0.03 mg/mL. Then, the absorbance of the CNT dispersion for measurement after dilution was measured under the same conditions as above, and the absorbance was defined as absorbance A (0.03) at a deemed concentration of 0.03 mg/mL. Further, in the same manner as above, the absorbance of a 0.8% by mass NMP solution of the polymer used for dilution was measured, and the absorbance was defined as absorbance A(0) at a deemed concentration of 0 mg/mL.
  • the absorbance of the supernatant liquid was measured under the same conditions as above, and the absorbance was defined as absorbance A' (0.06) at a deemed concentration of 0.06 mg/mL.
  • a 0.8% by mass NMP solution of the above polymer was added to the supernatant obtained above to dilute it twice on a volume basis to obtain a diluted supernatant.
  • the mass-to-volume concentration of the supernatant after dilution was assumed to be 0.03 mg/mL.
  • the absorbance of the diluted supernatant liquid was measured under the same conditions as above, and the absorbance was defined as absorbance A' (0.03) at a deemed concentration of 0.03 mg/mL.
  • the absorbance of a 0.8% by mass NMP solution of the polymer used for dilution was measured, and the absorbance was defined as absorbance A'(0) at a deemed concentration of 0 mg/mL. Then, on a graph where the vertical axis is the absorbance and the horizontal axis is the deemed concentration (mg/mL), A'(0), A'(0.03), and A'(0.06) obtained above are plotted. ) measurement results are plotted.
  • a calibration curve was created from the plotting results according to the Lambert-Beer law, and the slope of the obtained calibration curve was defined as the specific absorbance E2 of the supernatant liquid.
  • ⁇ Volume average particle diameter D50 of CNT in CNT dispersion> Using the CNT dispersions prepared in Examples and Comparative Examples, the dispersion during measurement was determined by dry integrated particle size distribution using a laser diffraction/scattering particle size distribution analyzer (Nikkishaso, "Microtrack MT3200II"). The volume-based average particle diameter D50 of the CNTs in the CNT dispersion was measured at an air pressure of 0.02 MPa.
  • Viscosity is less than 5000 mPa ⁇ s
  • B Viscosity is 5000 mPa ⁇ s or more and less than 10000 mPa ⁇ s
  • C Viscosity is 10000 mPa ⁇ s or more and less than 100000 mPa ⁇ s
  • D Viscosity is 100000 mPa ⁇ s or more
  • the obtained precipitate was dried in a vacuum dryer at 150° C. for 3 hours to obtain a dried product. At this time, it was confirmed that there was no change in mass due to drying.
  • This dried material is heat-treated to 500°C at a temperature increase rate of 10°C/min in a nitrogen atmosphere using a thermobalance, and the mass W1 (g) of the dried material before heat treatment is measured by the thermobalance. From the mass W2 (g) of the residue obtained after the heat treatment, the adsorption amount of the polymer to the conductive material (CNT) was calculated using the following formula, and evaluated according to the following criteria.
  • Adsorption amount (mg/g) ⁇ (W1-W2) ⁇ 1000 ⁇ /W2 A: 110 mg/g or more and 1000 mg/g or less B: 80 mg/g or more and less than 110 mg/g C: 60 mg/g or more and less than 80 mg/g D: 40 mg/g or more and less than 60 mg/g
  • ⁇ Viscosity stability of CNT dispersion> In order to determine the viscosity change rate of the CNT dispersions prepared in Examples and Comparative Examples, the following operation was performed. That is, using a rheometer ("MCR302" manufactured by Anton Paar), the viscosity of each of the above CNT dispersions immediately after preparation was measured under the conditions of a temperature of 25 ° C. and a shear rate of 2.5 s -1 . The viscosity obtained was defined as ⁇ 0. Next, the CNT dispersion liquid was sealed and left at 25° C. for one week (168 hours).
  • the viscosity of the CNT dispersion after being left for one week was measured under the same conditions as before being left for one week, and the obtained viscosity was defined as ⁇ 1.
  • Viscosity maintenance rate ⁇ is 90% or more and 110% or less
  • B Viscosity maintenance rate ⁇ is 80% or more and less than 90%
  • C Viscosity maintenance rate ⁇ is 70% or more and less than 80%
  • D Viscosity maintenance rate ⁇ is less than 70%, or more than 110%
  • ⁇ Cycle characteristics> The lithium ion secondary batteries produced in Examples and Comparative Examples were left standing at a temperature of 25° C. for 5 hours after injecting the electrolyte. Next, the battery was charged to a cell voltage of 3.65 V by a constant current method at a temperature of 25° C. and 0.2 C, and then an aging treatment was performed at a temperature of 60° C. for 12 hours. Then, the cell was discharged to a cell voltage of 3.00 V using a constant current method at a temperature of 25° C. and 0.2 C. Thereafter, CC-CV charging (upper limit cell voltage 4.20V) was performed using a constant current method at 0.2C, and CC discharge was performed to 3.00V using a constant current method at 0.2C.
  • CC-CV charging upper limit cell voltage 4.20V
  • the third discharge capacity at 0.2C was defined as the initial capacity CX.
  • CC-CV charging upper limit cell voltage 4.20V
  • the lithium ion secondary battery was stored for 4 weeks in an inner oven with a nitrogen atmosphere at 60° C. inside the processing chamber. Thereafter, the battery was discharged to a cell voltage of 3.00 V using a constant current method at 0.2 C, and the discharge capacity at this time was defined as CY.
  • the high temperature capacity retention rate expressed as (CY/CX) x 100 (%) was determined and evaluated based on the following criteria.
  • High temperature capacity retention rate is 90% or more
  • Example 1 ⁇ Preparation of polymer (binder composition)>
  • 200 parts of ion-exchanged water, 25 parts of a 10% concentration sodium dodecylbenzenesulfonate aqueous solution, 30 parts of acrylonitrile as a nitrile group-containing monomer unit, and 10 parts of methacrylic acid as a hydrophilic group-containing monomer unit were placed in a reactor.
  • 2.50 parts of t-dodecylmercaptan as a chain transfer agent were charged in this order.
  • 60 parts of 1,3-butadiene as a conjugated diene monomer was charged.
  • the aqueous dispersion and palladium catalyst (1% palladium acetate in acetone solution) were placed in an autoclave so that the palladium content was 3,000 ppm based on the solid weight contained in the aqueous dispersion of the obtained polymer precursor.
  • a solution prepared by mixing an equal weight of ion-exchanged water) was added, and a hydrogenation reaction was carried out at a hydrogen pressure of 3 MPa and a temperature of 55° C. for 3 hours to obtain an aqueous dispersion of the desired polymer (hydrogenated nitrile rubber). Thereafter, the contents were returned to room temperature, the inside of the system was made into a nitrogen atmosphere, and then concentrated using an evaporator until the solid content concentration reached 40%.
  • a 2.5% KOH aqueous solution was added to the concentrated aqueous polymer dispersion to adjust the pH to 9.5.
  • the haze and iodine value were measured using the aqueous dispersion of the polymer after pH adjustment.
  • an 8% by mass NMP solution of the polymer was obtained.
  • the weight average molecular weight of the polymer and the amount of adsorption of the polymer to CNTs were measured and evaluated.
  • a ternary active material LiNi 0.6 Co 0.2 Mn 0.2 O 2
  • polyvinylidene fluoride as a binder
  • the amount of NMP added is determined when the viscosity of the resulting positive electrode slurry composition (measured using a single cylindrical rotational viscometer according to JIS Z8803:1991, temperature: 25°C, rotation speed: 60 rpm) is 4000 to 5000 mPa. Adjusted to be within the range of s.
  • Aluminum foil with a thickness of 20 ⁇ m was prepared as a current collector.
  • the positive electrode slurry obtained as described above was applied to one side of aluminum foil using a comma coater so that the drying weight was 20 mg/cm 2 , and after drying at 90°C for 20 minutes and at 120°C for 20 minutes, A positive electrode material was obtained by heat treatment at 60° C. for 10 hours.
  • This positive electrode material was rolled with a roll press to produce a sheet-like positive electrode consisting of a positive electrode composite material layer having a density of 3.2 g/cm 3 and aluminum foil. Then, the sheet-like positive electrode was cut into pieces with a width of 48.0 mm and a length of 47 cm to obtain a positive electrode for a lithium ion secondary battery.
  • ⁇ Preparation of negative electrode> In a 5 MPa pressure vessel equipped with a stirrer, 33 parts of 1,3-butadiene as an aliphatic conjugated diene monomer, 3.5 parts of itaconic acid as a carboxylic acid group-containing monomer, and styrene as an aromatic vinyl monomer. Add 63.5 parts of sodium dodecylbenzenesulfonate as an emulsifier, 150 parts of ion-exchanged water, and 0.5 parts of potassium persulfate as a polymerization initiator, stir thoroughly, and then heat to 50°C. Polymerization was initiated by heating.
  • the polymerization reaction was stopped by cooling to obtain a mixture containing a particulate binder (styrene-butadiene copolymer).
  • a particulate binder styrene-butadiene copolymer
  • pH 8
  • a 5% aqueous sodium hydroxide solution unreacted monomers were removed by heating and vacuum distillation.
  • the mixture was cooled to 30° C. or lower to obtain an aqueous dispersion containing a negative electrode binder.
  • 48.75 parts of artificial graphite and 48.75 parts of natural graphite as negative electrode active materials, and 1 part of carboxymethyl cellulose (equivalent to solid content) as a thickener were charged into a planetary mixer.
  • the mixture was diluted with ion-exchanged water to a solid concentration of 60%, and then kneaded for 60 minutes at a rotational speed of 45 rpm. Thereafter, 1.5 parts of the aqueous dispersion containing the negative electrode binder obtained as described above was added in terms of solid content, and kneaded at a rotational speed of 40 rpm for 40 minutes. Then, ion-exchanged water was added so that the viscosity was 3000 ⁇ 500 mPa ⁇ s (measured with a B-type viscometer, 25° C., 60 rpm) to prepare a slurry composition for a negative electrode.
  • the above slurry composition for a negative electrode was applied to the surface of a 15 ⁇ m thick copper foil serving as a current collector using a comma coater so that the coating amount was 10 ⁇ 0.5 mg/cm 2 . Thereafter, the copper foil coated with the negative electrode slurry composition was transported at a speed of 400 mm/min in an oven at a temperature of 80°C for 2 minutes, and then in an oven at a temperature of 110°C for 2 minutes. The slurry composition on the foil was dried to obtain a negative electrode original fabric in which a negative electrode composite layer was formed on the current collector.
  • This negative electrode material was rolled using a roll press to produce a sheet negative electrode consisting of a negative electrode composite material layer having a density of 1.6 g/cm 3 and aluminum foil.
  • the sheet-like negative electrode was then cut into pieces with a width of 50.0 mm and a length of 52 cm to obtain a negative electrode for a lithium ion secondary battery.
  • ⁇ Production of separator with adhesive layer> 100 parts of ion-exchanged water and 0.5 parts of ammonium persulfate were each supplied to a reactor equipped with a stirrer, the gas phase was replaced with nitrogen gas, and the temperature was raised to 70°C. Meanwhile, in another container, 40 parts of ion-exchanged water, 0.3 parts of sodium dodecylbenzenesulfonate as an emulsifier, 24.5 parts of n-butyl acrylate and 28 parts of methyl methacrylate as (meth)acrylic acid ester monomers.
  • this aqueous dispersion was heated to 75°C, and 1.7 parts of acrylonitrile as a nitrile group-containing monomer and 0.3 parts of methacrylic acid (MAA) as an acid group-containing monomer were added to the aqueous dispersion. and 28.0 parts of styrene (ST) as an aromatic monomer were mixed and continuously added to continue the polymerization.
  • the reaction was stopped by cooling to obtain an aqueous dispersion containing adhesive polymer B1.
  • the obtained adhesive polymer B1 had a core-shell structure in which the outer surface of the core portion was partially covered with the shell portion.
  • aqueous dispersion containing adhesive polymer B2 >> 70 parts of ion-exchanged water, 0.2 parts of sodium dodecylbenzenesulfonate as an emulsifier, and 0.5 parts of ammonium persulfate were each supplied to a reactor equipped with a stirrer, and the gas phase was replaced with nitrogen gas. Then, the temperature was raised to 75°C.
  • slurry composition for adhesive layer >100 parts (equivalent to solid content) of an aqueous dispersion of adhesive polymer B1, 15 parts (equivalent to solid content) of an aqueous dispersion of adhesive polymer B2, and ion-exchanged water are mixed to form a slurry for an adhesive layer.
  • a composition solid content concentration: 10%
  • a polyethylene separator base material manufactured by Asahi Kasei Co., Ltd., trade name "ND412", thickness: 12 ⁇ m
  • a ceramic slurry (BM-2000M, manufactured by Nippon Zeon) was applied to the surface of the prepared separator base material and dried at a temperature of 50°C for 3 minutes to form a separator with a heat-resistant layer on one side (heat-resistant layer thickness: 2 ⁇ m). Obtained.
  • the slurry composition for a functional layer obtained above was applied to one side of the separator provided with the heat-resistant layer, and dried at a temperature of 50° C. for 3 minutes.
  • the same operation was performed on the other side of the separator base material to obtain a separator with an adhesive layer in which adhesive layers were formed on both sides. After drying, the adhesive layer formed on both sides had a basis weight of 0.25 g/m 2 .
  • the prepared positive electrode for a lithium ion secondary battery and the negative electrode for a lithium ion secondary battery were placed so that the electrode mixture layers faced each other, and the separator with the adhesive layer prepared above was interposed and wound using a core with a diameter of 20 mm. Turn it to obtain a rolled body.
  • the separator with an adhesive layer was placed so that the surface on which the adhesive layer was further formed on the heat-resistant layer faced the positive electrode. Then, the obtained wound body was compressed from one direction at a speed of 10 mm/sec until it had a thickness of 4.5 mm.
  • the wound body after compression had an elliptical shape in plan view, and the ratio of the major axis to the minor axis (major axis/minor axis) was 7.7.
  • a lithium ion secondary battery as an electrochemical device was obtained.
  • This lithium ion secondary battery was in the form of a pouch with a width of 35 mm, a height of 60 mm, and a thickness of 5 mm, and the nominal capacity of the battery was 700 mAh.
  • the cycle characteristics and high temperature storage characteristics of the obtained lithium ion secondary battery were evaluated. The results are shown in Table 1.
  • Examples 2-3 When preparing the polymer (binder composition) of Example 1, acrylonitrile as a nitrile group-containing monomer, methacrylic acid as a hydrophilic group-containing monomer, and 1, as a conjugated diene monomer. Preparation of a polymer (binder composition) in the same manner as in Example 1, except that the amount of each of 3-butadiene added was changed so that the composition of the resulting polymer was as shown in Table 1. A CNT dispersion liquid, a positive electrode slurry composition, a positive electrode, a negative electrode, a separator with an adhesive layer, and a lithium ion secondary battery were prepared, and various measurements and evaluations were performed. The results are shown in Table 1.
  • Example 4 The same procedure as that of Example 1 was performed except that the amount of t-dodecyl mercaptan added as a chain transfer agent was changed from 2.50 parts to 0.4 parts during the preparation of the polymer (binder composition) of Example 1. Similarly, preparation of polymer (binder composition), preparation of CNT dispersion, preparation of slurry composition for positive electrode, preparation of positive electrode, preparation of negative electrode, preparation of separator with adhesive layer, preparation of lithium ion secondary battery. We carried out various measurements and evaluations. The results are shown in Table 1.
  • Example 5 During the preparation of the polymer (binder composition) of Example 1, the amount of palladium catalyst added was adjusted so that the palladium content was 3. Except for changing the amount from 000 ppm to 1,500 ppm, the same procedures as in Example 1 were carried out, including preparation of a polymer (binder composition), preparation of a CNT dispersion, preparation of a slurry composition for a positive electrode, production of a positive electrode, and preparation of a negative electrode. A separator with an adhesive layer was manufactured, a lithium ion secondary battery was manufactured, and various measurements and evaluations were performed. The results are shown in Table 1.
  • Example 6 When preparing the polymer (binder composition) of Example 1, the amount of acrylonitrile added as a nitrile group-containing monomer was changed from 30 parts to 25 parts, and the amount of 1,3- as a conjugated diene monomer was changed from 30 parts to 25 parts.
  • Example 7 When preparing the polymer (binder composition) of Example 1, the amount of acrylonitrile added as a nitrile group-containing monomer was changed from 30 parts to 25 parts, and the amount of 1,3- as a conjugated diene monomer was changed from 30 parts to 25 parts.
  • a polymer (binder composition) was prepared in the same manner as in Example 1, except that the amount of butadiene added was changed from 60 parts to 55 parts, and 10 parts of styrene as an aromatic vinyl monomer was further added.
  • a polymer (binder composition) was prepared in the same manner as in Example 1, except that the palladium content relative to the solid weight contained in the aqueous dispersion of the polymer precursor was changed from 3,000 ppm to 800 ppm.
  • a CNT dispersion was prepared, a positive electrode slurry composition was prepared, a positive electrode was prepared, a negative electrode was prepared, a separator with an adhesive layer was prepared, a lithium ion secondary battery was prepared, and various measurements and evaluations were performed. The results are shown in Table 1.
  • Example 4 Except that when preparing the CNT dispersion liquid in Example 1, the stirring time using a thin film rotating high-speed mixer ("Filmix (registered trademark) 40-L type" manufactured by Primix Corporation) was changed from 120 seconds to 10 seconds.
  • a thin film rotating high-speed mixer (“Filmix (registered trademark) 40-L type” manufactured by Primix Corporation) was changed from 120 seconds to 10 seconds.
  • preparation of a polymer (binder composition) preparation of a CNT dispersion, preparation of a slurry composition for a positive electrode, preparation of a positive electrode, preparation of a negative electrode, preparation of a separator with an adhesive layer, and preparation of a lithium An ion secondary battery was fabricated, and various measurements and evaluations were performed. The results are shown in Table 1.
  • the palladium content based on the solid weight contained in the aqueous dispersion of the polymer precursor was changed from 3,000 ppm to 300 ppm, and further, during the preparation of the CNT dispersion of Example 1, a thin film rotating high-speed Except that a bead mill using zirconia beads with a diameter of 1 mm was used instead of a mixer ("Filmix (registered trademark) 40-L type" manufactured by Primix), and mixing was performed for 3600 seconds at a peripheral speed of 8 m/s.
  • “Filmix” means “Filmix (registered trademark) 40-L type” manufactured by Primix Corporation.
  • the CNT dispersions of Examples 1 to 7, which contain carbon nanotubes, a predetermined polymer, and a dispersion medium, and in which the value of the change rate ⁇ E of specific absorbance before and after centrifugation treatment is less than a predetermined value, are It can be seen that the dispersibility of CNTs is excellent compared to the CNT dispersions of Comparative Examples 1 to 6 in which the value of the change rate ⁇ E of specific absorbance before and after treatment is equal to or greater than a predetermined value.
  • the present invention it is possible to provide a carbon nanotube dispersion liquid with excellent dispersibility of carbon nanotubes. Further, according to the present invention, it is possible to provide a slurry composition for a non-aqueous secondary battery electrode prepared using the carbon nanotube dispersion. Furthermore, according to the present invention, it is possible to provide an electrode for a non-aqueous secondary battery formed using the slurry composition for a non-aqueous secondary battery electrode. Further, according to the present invention, it is possible to provide a non-aqueous secondary battery including the non-aqueous secondary battery electrode.

Abstract

The purpose of the present invention is to provide a carbon nanotube dispersion having excellent dispersibility of carbon nanotubes. The carbon nanotube dispersion of the present invention contains carbon nanotubes, a polymer, and a dispersion medium and is characterized in that the polymer contains a nitrile group-containing monomer unit, an alkylene structure unit, and a hydrophilic group-containing monomer unit and the rate of change ΔE in the specific absorbance before and after centrifugation, obtained by the formula: ΔE=100×(E1−E2)/E1 [%] taking the specific absorbance of the carbon nanotube dispersion as E1 and the specific absorbance of the supernatant obtained by centrifuging the carbon nanotube dispersion for one minute at 4000 rpm as E2, is less than 50%.

Description

カーボンナノチューブ分散液、非水系二次電池電極用スラリー組成物、非水系二次電池用電極、及び非水系二次電池Carbon nanotube dispersion liquid, slurry composition for non-aqueous secondary battery electrodes, electrode for non-aqueous secondary batteries, and non-aqueous secondary batteries
　本発明は、カーボンナノチューブ分散液、非水系二次電池電極用スラリー組成物、非水系二次電池用電極、及び非水系二次電池に関するものである。 The present invention relates to a carbon nanotube dispersion, a slurry composition for a non-aqueous secondary battery electrode, an electrode for a non-aqueous secondary battery, and a non-aqueous secondary battery.
　リチウムイオン二次電池などの非水系二次電池（以下、「二次電池」と略記する場合がある。）は、小型で軽量、且つエネルギー密度が高く、さらに繰り返し充放電が可能という特性があり、幅広い用途に使用されている。そのため、近年では、非水系二次電池の更なる高性能化を目的として、電極などの電池部材の改良が検討されている。 Non-aqueous secondary batteries (hereinafter sometimes abbreviated as "secondary batteries") such as lithium-ion secondary batteries have the characteristics of being small, lightweight, and have high energy density, and can be repeatedly charged and discharged. , used in a wide range of applications. Therefore, in recent years, improvements in battery components such as electrodes have been studied with the aim of further improving the performance of non-aqueous secondary batteries.
　ここで、非水系二次電池用の電極は、通常、集電体と、集電体上に形成された電極合材層とを備えている。そして、この電極合材層は、例えば、電極活物質と、結着材としての重合体と、導電材などとを分散媒に分散させてなるスラリー組成物を用いて形成される。 Here, an electrode for a non-aqueous secondary battery usually includes a current collector and an electrode mixture layer formed on the current collector. The electrode composite material layer is formed using, for example, a slurry composition in which an electrode active material, a polymer as a binder, a conductive material, and the like are dispersed in a dispersion medium.
　近年では、非水系二次電池の更なる性能の向上を達成すべく、非水系二次電池の電極の構成要素である電極合材層の形成に用いられるスラリー組成物の改良が試みられている。 In recent years, in order to further improve the performance of non-aqueous secondary batteries, attempts have been made to improve the slurry composition used to form the electrode mixture layer, which is a component of the electrode of non-aqueous secondary batteries. .
　具体的には、ニトリル基含有単量体単位及び水素化した共役ジエン単量体単位を含有する重合体を用いた非水系二次電池電極用スラリー組成物が種々検討され、提供されてきた（例えば、特許文献１～５参照）。 Specifically, various slurry compositions for nonaqueous secondary battery electrodes using polymers containing nitrile group-containing monomer units and hydrogenated conjugated diene monomer units have been studied and provided ( For example, see Patent Documents 1 to 5).
国際公開第２０１３／０８０９８９号International Publication No. 2013/080989 特開２０１３－１７９０４０号公報Japanese Patent Application Publication No. 2013-179040 国際公開第２０１９／１８１８６９号International Publication No. 2019/181869 特開２０２０－０１９７０５号JP2020-019705 特開２０２０－１８７８６６号公報JP2020-187866
　ここで、電極合材層の形成に用いられるスラリー組成物には、導電材としてカーボンナノチューブ（以下、「ＣＮＴ」と略記する場合がある。）を好適に用いることができる。もっとも、カーボンナノチューブは、通常、凝集し易く、分散させ難い。そこで、二次電池の生産性及び性能を高めるため、カーボンナノチューブと結着材としての重合体と分散媒とを混合してカーボンナノチューブ分散液を予め調製した上で、得られたカーボンナノチューブ分散液と電極活物質などとを混合することによりスラリー組成物を調製する場合がある。そして、スラリー組成物の調製の前段階で調製されるカーボンナノチューブ分散液においては、カーボンナノチューブの分散性に優れていることが求められる。 Here, carbon nanotubes (hereinafter sometimes abbreviated as "CNT") can be suitably used as a conductive material in the slurry composition used to form the electrode composite material layer. However, carbon nanotubes usually tend to aggregate and are difficult to disperse. Therefore, in order to improve the productivity and performance of secondary batteries, a carbon nanotube dispersion liquid is prepared in advance by mixing carbon nanotubes, a polymer as a binder, and a dispersion medium, and the obtained carbon nanotube dispersion liquid is A slurry composition may be prepared by mixing the electrode active material and the like. The carbon nanotube dispersion liquid prepared before the preparation of the slurry composition is required to have excellent dispersibility of carbon nanotubes.
　そこで、本発明は、カーボンナノチューブの分散性に優れたカーボンナノチューブ分散液を提供することを目的とする。
　また、本発明は、当該カーボンナノチューブ分散液を用いて調製した非水系二次電池電極用スラリー組成物を提供することを目的とする。
　さらに、本発明は、当該非水系二次電池電極用スラリー組成物を用いて形成した電極合材層を備える非水系二次電池用電極を提供することを目的とする。
　そして、本発明は、当該非水系二次電池用電極を備える非水系二次電池を提供することを目的とする。 Therefore, an object of the present invention is to provide a carbon nanotube dispersion liquid with excellent dispersibility of carbon nanotubes.
Another object of the present invention is to provide a slurry composition for a nonaqueous secondary battery electrode prepared using the carbon nanotube dispersion.
Furthermore, an object of the present invention is to provide an electrode for a non-aqueous secondary battery including an electrode mixture layer formed using the slurry composition for a non-aqueous secondary battery electrode.
And, an object of the present invention is to provide a non-aqueous secondary battery including the electrode for a non-aqueous secondary battery.
　本発明者は、上記目的を達成するために鋭意検討を行った。そして、本発明者は、カーボンナノチューブと、所定の重合体とを含み、遠心処理前後の比吸光度の変化率が所定値未満であるカーボンナノチューブ分散液であれば、カーボンナノチューブの分散性に優れていることを見出し、本発明を完成させた。 The present inventor conducted extensive studies in order to achieve the above object. The present inventor also found that a carbon nanotube dispersion containing carbon nanotubes and a predetermined polymer and having a rate of change in specific absorbance before and after centrifugation treatment that is less than a predetermined value has excellent dispersibility of carbon nanotubes. The present invention was completed based on the discovery that
　即ち、この発明は、上記課題を有利に解決することを目的とするものであり、本発明は、［１］カーボンナノチューブ、重合体、及び分散媒を含むカーボンナノチューブ分散液であって、前記重合体が、ニトリル基含有単量体単位と、アルキレン構造単位と、親水性基含有単量体単位とを含有し、前記カーボンナノチューブ分散液の比吸光度をＥ１とし、前記カーボンナノチューブ分散液を４０００ｒｐｍで１分間遠心処理して得られる上澄み液の比吸光度をＥ２とした場合に、式：ΔＥ＝１００×（Ｅ１－Ｅ２）／Ｅ１［％］により得られる遠心処理前後の比吸光度の変化率ΔＥが５０％未満である、カーボンナノチューブ分散液である。
　このように、カーボンナノチューブと、ニトリル基含有単量体単位、アルキレン構造単位、及び親水性基含有単量体単位を含有する重合体とを含み、遠心処理前後の比吸光度の変化率が所定値未満であるカーボンナノチューブ分散液は、カーボンナノチューブの分散性に優れている。
　なお、本発明において、重合体の「単量体単位」とは、「その単量体を用いて得た重合体中に含まれる、当該単量体由来の繰り返し単位」を意味する。
　また、本発明において、カーボンナノチューブ分散液の比吸光度Ｅ１、上澄み液の比吸光度Ｅ２、及び遠心処理前後の比吸光度の変化率ΔＥは、本明細書の実施例に記載の方法に従って測定及び算出することができる。 That is, an object of the present invention is to advantageously solve the above problems, and the present invention provides [1] a carbon nanotube dispersion containing carbon nanotubes, a polymer, and a dispersion medium, which The aggregate contains a nitrile group-containing monomer unit, an alkylene structural unit, and a hydrophilic group-containing monomer unit, the specific absorbance of the carbon nanotube dispersion is set to E1, and the carbon nanotube dispersion is heated at 4000 rpm. When the specific absorbance of the supernatant obtained by centrifugation for 1 minute is E2, the rate of change in specific absorbance ΔE before and after centrifugation is obtained by the formula: ΔE = 100 x (E1-E2)/E1 [%]. 50% carbon nanotube dispersion.
In this way, a polymer containing carbon nanotubes, a nitrile group-containing monomer unit, an alkylene structural unit, and a hydrophilic group-containing monomer unit has a specific absorbance change rate of a predetermined value before and after centrifugation treatment. A carbon nanotube dispersion liquid having a carbon nanotube dispersion of less than 10% has excellent dispersibility of carbon nanotubes.
In the present invention, the "monomer unit" of a polymer means "a repeating unit derived from the monomer and contained in a polymer obtained using the monomer."
Furthermore, in the present invention, the specific absorbance E1 of the carbon nanotube dispersion, the specific absorbance E2 of the supernatant, and the rate of change ΔE in the specific absorbance before and after centrifugation are measured and calculated according to the method described in the Examples of this specification. be able to.
　［２］上記［１］のカーボンナノチューブ分散液において、前記重合体の重量平均分子量が２，０００以上２００，０００以下であることが好ましい。
　重合体の重量平均分子量が上記所定値の範囲内であれば、重合体のＣＮＴに対する吸着量が増大し、ＣＮＴ分散液中のＣＮＴの分散性を更に向上させると共に、ＣＮＴ分散液の粘度安定性を向上させることができる。また、重合体の重量平均分子量が上記所定の範囲内であれば、ＣＮＴ分散液を含むスラリー組成物を用いて形成した電極合材層を備える二次電池のサイクル特性及び高温保存特性を向上させることができる。
　なお、重合体の重量平均分子量は、本明細書の実施例に記載の方法に従って測定することができる。 [2] In the carbon nanotube dispersion liquid of [1] above, it is preferable that the weight average molecular weight of the polymer is 2,000 or more and 200,000 or less.
If the weight average molecular weight of the polymer is within the above predetermined range, the adsorption amount of the polymer to CNTs will increase, further improving the dispersibility of CNTs in the CNT dispersion liquid, and improving the viscosity stability of the CNT dispersion liquid. can be improved. Furthermore, if the weight average molecular weight of the polymer is within the above-described range, the cycle characteristics and high-temperature storage characteristics of a secondary battery including an electrode composite layer formed using a slurry composition containing a CNT dispersion can be improved. be able to.
Note that the weight average molecular weight of the polymer can be measured according to the method described in the Examples of this specification.
　［３］上記［１］又は［２］のカーボンナノチューブ分散液において、前記重合体の８質量％水溶液のヘイズがｐＨ８．０以上において７０％以下であることが好ましい。
　重合体の上記所定の水溶液のヘイズが上記所定値以下であれば、重合体のＣＮＴに対する吸着量が増大するので、ＣＮＴ分散液中のＣＮＴの分散性を更に向上させると共に、ＣＮＴ分散液の粘度安定性を向上させることができる。また、重合体の上記所定の水溶液のヘイズが上記所定値以下であれば、ＣＮＴ分散液を含むスラリー組成物を用いて形成した電極合材層を備える二次電池のサイクル特性及び高温保存特性を向上させることができる。
　なお、本発明において、重合体の８質量％水溶液のヘイズは、本明細書の実施例に記載の方法に従って測定することができる。 [3] In the carbon nanotube dispersion liquid of [1] or [2] above, it is preferable that the haze of the 8% by mass aqueous solution of the polymer is 70% or less at pH 8.0 or higher.
If the haze of the above-mentioned predetermined aqueous solution of the polymer is below the above-mentioned predetermined value, the adsorption amount of the polymer to CNTs will increase, which will further improve the dispersibility of CNTs in the CNT dispersion, and will also reduce the viscosity of the CNT dispersion. Stability can be improved. In addition, if the haze of the above-mentioned predetermined aqueous solution of the polymer is below the above-mentioned predetermined value, the cycle characteristics and high-temperature storage characteristics of a secondary battery equipped with an electrode composite layer formed using a slurry composition containing a CNT dispersion can be improved. can be improved.
In the present invention, the haze of an 8% by mass aqueous solution of the polymer can be measured according to the method described in the Examples of this specification.
　［４］上記［１］～［３］のいずれかのカーボンナノチューブ分散液において、前記重合体中のアルキレン構造単位及び共役ジエン単量体単位の合計含有割合が、３０質量％以上８０質量％以下であることが好ましい。
　重合体中のアルキレン構造単位及び共役ジエン単量体単位の合計含有割合が上記所定の範囲内であれば、ＣＮＴ分散液中のＣＮＴの分散性を更に向上させることができる。
　なお、本発明において、重合体中の各種の繰り返し単位（単量体単位及び構造単位）の含有割合は、１Ｈ－ＮＭＲなどの核磁気共鳴（ＮＭＲ）法を用いて測定することができる。 [4] In the carbon nanotube dispersion according to any one of [1] to [3] above, the total content of alkylene structural units and conjugated diene monomer units in the polymer is 30% by mass or more and 80% by mass or less It is preferable that
If the total content of alkylene structural units and conjugated diene monomer units in the polymer is within the above-mentioned predetermined range, the dispersibility of CNTs in the CNT dispersion can be further improved.
In the present invention, the content ratio of various repeating units (monomer units and structural units) in the polymer can be measured using a nuclear magnetic resonance (NMR) method such as 1 H-NMR.
　［５］上記［１］～［４］のいずれかのカーボンナノチューブ分散液において、前記重合体のヨウ素価が、５ｍｇ／１００ｍｇ以上１００ｍｇ／１００ｍｇ以下であることが好ましい。
　重合体のヨウ素価が上記所定の範囲内であれば、ＣＮＴ分散液中のＣＮＴの分散性を更に向上させると共に、ＣＮＴ分散液の粘度安定性を向上させることができる。また、重合体のヨウ素価が上記所定の範囲内であれば、ＣＮＴ分散液を含むスラリー組成物を用いて形成した電極合材層を備える二次電池のサイクル特性及び高温保存特性を向上させることができる。
　なお、本発明において、重合体のヨウ素価は、本明細書の実施例に記載の方法に従って測定することができる。 [5] In the carbon nanotube dispersion according to any one of [1] to [4] above, the iodine value of the polymer is preferably 5 mg/100 mg or more and 100 mg/100 mg or less.
If the iodine value of the polymer is within the above-mentioned predetermined range, the dispersibility of CNTs in the CNT dispersion can be further improved, and the viscosity stability of the CNT dispersion can be improved. Furthermore, if the iodine value of the polymer is within the above-mentioned predetermined range, the cycle characteristics and high-temperature storage characteristics of a secondary battery including an electrode composite layer formed using a slurry composition containing a CNT dispersion can be improved. Can be done.
In addition, in this invention, the iodine value of a polymer can be measured according to the method described in the Example of this specification.
　［６］上記［１］～［５］のいずれかのカーボンナノチューブ分散液において、前記重合体中のニトリル基含有単量体単位の含有割合が１０質量％以上５５質量％以下であることが好ましい。
　重合体中のニトリル基含有単量体単位の含有割合が上記所定の範囲内であれば、ＣＮＴ分散液中のＣＮＴの分散性を更に向上させることができる。 [6] In the carbon nanotube dispersion according to any one of [1] to [5] above, the content of the nitrile group-containing monomer unit in the polymer is preferably 10% by mass or more and 55% by mass or less. .
If the content of the nitrile group-containing monomer unit in the polymer is within the above-mentioned predetermined range, the dispersibility of CNTs in the CNT dispersion can be further improved.
　［７］上記［１］～［６］のいずれかのカーボンナノチューブ分散液において、前記カーボンナノチューブの分散粒径の粒度分布における体積平均粒子径Ｄ５０の値が、０．１μｍ以上１５．０μｍ以下であることが好ましい。
　ＣＮＴ分散液中のＣＮＴの体積平均粒子径が上記所定の範囲内であれば、ＣＮＴ分散液中のＣＮＴの分散性を更に向上させることができる。
　なお、ＣＮＴの体積平均粒子径Ｄ５０は、本明細書の実施例に記載の方法に従って測定することができる。 [7] In the carbon nanotube dispersion liquid according to any one of [1] to [6] above, the value of the volume average particle diameter D50 in the particle size distribution of the dispersed particle size of the carbon nanotubes is 0.1 μm or more and 15.0 μm or less. It is preferable that there be.
If the volume average particle diameter of CNTs in the CNT dispersion liquid is within the above-mentioned predetermined range, the dispersibility of CNTs in the CNT dispersion liquid can be further improved.
Note that the volume average particle diameter D50 of CNT can be measured according to the method described in Examples of this specification.
　［８］上記［１］～［７］のいずれかのカーボンナノチューブ分散液において、前記重合体中の親水性基含有単量体単位の含有割合が６．５質量％以上５０質量％以下であることが好ましい。
　重合体中の親水性基含有単量体単位の含有割合が上記所定の範囲内であれば、重合体のＣＮＴに対する吸着量が増大し、ＣＮＴ分散液中のＣＮＴの分散性を更に向上させると共に、ＣＮＴ分散液の粘度安定性を向上させることができる。また、重合体中における親水性基含有単量体単位の含有割合が上記所定の範囲内であれば、ＣＮＴ分散液を含むスラリー組成物を用いて形成した電極合材層を備える二次電池のサイクル特性及び高温保存特性を向上させることができる。 [8] In the carbon nanotube dispersion according to any one of [1] to [7] above, the content of hydrophilic group-containing monomer units in the polymer is 6.5% by mass or more and 50% by mass or less. It is preferable.
If the content of the hydrophilic group-containing monomer unit in the polymer is within the above-determined range, the adsorption amount of the polymer to CNTs will increase, further improving the dispersibility of CNTs in the CNT dispersion, and , the viscosity stability of the CNT dispersion can be improved. Further, if the content ratio of the hydrophilic group-containing monomer unit in the polymer is within the above-determined range, a secondary battery including an electrode composite layer formed using a slurry composition containing a CNT dispersion may be used. Cycle characteristics and high temperature storage characteristics can be improved.
　［９］上記［１］～［８］のいずれかのカーボンナノチューブ分散液において、前記重合体が（メタ）アクリル酸エステル単量体単位を含有しないことが好ましい。
　（メタ）アクリル酸エステル単量体単位を含有しない重合体を用いれば、ＣＮＴ分散液中のＣＮＴの分散性を更に向上させることができる。
　なお、本発明において「（メタ）アクリル」とは、アクリル及び／又はメタクリルを意味する。 [9] In the carbon nanotube dispersion liquid according to any one of [1] to [8] above, it is preferable that the polymer does not contain a (meth)acrylic acid ester monomer unit.
If a polymer containing no (meth)acrylic acid ester monomer unit is used, the dispersibility of CNTs in the CNT dispersion can be further improved.
In addition, in the present invention, "(meth)acrylic" means acrylic and/or methacryl.
　［１０］上記［１］～［９］のいずれかのカーボンナノチューブ分散液において、前記重合体が芳香族ビニル単量体単位を含有しないことが好ましい。
　芳香族ビニル単量体単位を含有しない重合体を用いれば、ＣＮＴ分散液中のＣＮＴの分散性を更に向上させることができる。 [10] In the carbon nanotube dispersion liquid according to any one of [1] to [9] above, it is preferable that the polymer does not contain aromatic vinyl monomer units.
By using a polymer that does not contain aromatic vinyl monomer units, the dispersibility of CNTs in the CNT dispersion can be further improved.
　そして、この発明は、上記課題を有利に解決することを目的とするものであり、本発明は、［１１］電極活物質と、上記［１］～［１０］のいずれかのカーボンナノチューブ分散液とを含む、非水系二次電池電極用スラリー組成物である。
　このように、上述したいずれかのＣＮＴ分散液を含む非水系二次電池電極用スラリー組成物であれば、二次電池に優れた電池特性（例えば、サイクル特性及び高温保存特性など）を発揮させ得る電極合材層を有する電極を形成することができる。 The purpose of the present invention is to advantageously solve the above-mentioned problems. A slurry composition for a non-aqueous secondary battery electrode, comprising:
In this way, a slurry composition for a non-aqueous secondary battery electrode containing any of the above-mentioned CNT dispersions allows a secondary battery to exhibit excellent battery characteristics (such as cycle characteristics and high-temperature storage characteristics). An electrode having the electrode composite material layer obtained can be formed.
　さらに、この発明は、上記課題を有利に解決することを目的とするものであり、本発明は、［１２］上記［１１］の非水系二次電池電極用スラリー組成物を用いて形成した電極合材層を備える、非水系二次電池用電極である。
　このように、上述した非水系二次電池電極用スラリー組成物を用いて形成した電極合材層を有する電極を使用すれば、例えば、サイクル特性及び高温保存特性などの電池特性に優れた非水系二次電池を安定的に得ることができる。 Furthermore, the present invention aims to advantageously solve the above problems, and the present invention provides an electrode formed using the slurry composition for non-aqueous secondary battery electrodes according to [12] above [11]. This is an electrode for a non-aqueous secondary battery that includes a composite material layer.
In this way, if an electrode having an electrode mixture layer formed using the above-described slurry composition for non-aqueous secondary battery electrodes is used, for example, a non-aqueous secondary battery electrode with excellent battery characteristics such as cycle characteristics and high-temperature storage characteristics can be used. A secondary battery can be stably obtained.
　また、この発明は、上記課題を有利に解決することを目的とするものであり、本発明は、［１３］上記［１２］の非水系二次電池用電極を備える、非水系二次電池である。
　このように、上述した非水系二次電池用電極を使用すれば、例えば、サイクル特性及び高温保存特性などの電池特性に優れた非水系二次電池が得られる。 [13] The present invention also provides a non-aqueous secondary battery comprising the electrode for a non-aqueous secondary battery according to [12] above. be.
In this way, by using the above-mentioned electrode for a non-aqueous secondary battery, a non-aqueous secondary battery having excellent battery characteristics such as cycle characteristics and high-temperature storage characteristics can be obtained.
　本発明によれば、カーボンナノチューブの分散性に優れたカーボンナノチューブ分散液を提供することができる。
　さらに、本発明によれば、当該カーボンナノチューブ分散液を用いて調製した非水系二次電池電極用スラリー組成物を提供することができる。
　また、本発明によれば、当該非水系二次電池電極用スラリー組成物を用いて形成した非水系二次電池用電極を提供することができる。
　さらに、本発明によれば、当該非水系二次電池用電極を備える非水系二次電池を提供することができる。 According to the present invention, it is possible to provide a carbon nanotube dispersion liquid with excellent dispersibility of carbon nanotubes.
Furthermore, according to the present invention, it is possible to provide a slurry composition for a non-aqueous secondary battery electrode prepared using the carbon nanotube dispersion.
Further, according to the present invention, it is possible to provide an electrode for a non-aqueous secondary battery formed using the slurry composition for a non-aqueous secondary battery electrode.
Furthermore, according to the present invention, a non-aqueous secondary battery including the non-aqueous secondary battery electrode can be provided.
　以下、本発明の実施形態について詳細に説明する。
　ここで、本発明のＣＮＴ分散液は、本発明の非水系二次電池電極用スラリー組成物（以下、単に「スラリー組成物」と称する場合がある。）の調製に用いることができる。さらに、本発明の非水系二次電池電極用スラリー組成物は、リチウムイオン二次電池等の非水系二次電池の電極を製造する際に用いることができる。また、本発明の非水系二次電池は、本発明の非水系二次電池電極用スラリー組成物を用いて形成した本発明の非水系二次電池用電極（以下、単に「電極」と称する場合がある。）を用いたことを特徴とする。 Embodiments of the present invention will be described in detail below.
Here, the CNT dispersion of the present invention can be used for preparing the slurry composition for non-aqueous secondary battery electrodes of the present invention (hereinafter sometimes simply referred to as "slurry composition"). Furthermore, the slurry composition for a non-aqueous secondary battery electrode of the present invention can be used when manufacturing an electrode for a non-aqueous secondary battery such as a lithium ion secondary battery. In addition, the non-aqueous secondary battery of the present invention includes an electrode for a non-aqueous secondary battery of the present invention (hereinafter simply referred to as "electrode") formed using the slurry composition for a non-aqueous secondary battery electrode of the present invention. ).
（ＣＮＴ分散液）
　本発明のＣＮＴ分散液は、ＣＮＴ、所定の重合体、及び分散媒を含み、所定の遠心処理前後の比吸光度の変化率が所定値未満であることを特徴とする。そして、本発明のＣＮＴ分散液は、ＣＮＴの分散性に優れている。したがって、本発明のＣＮＴ分散液を用いて調製したスラリー組成物によれば、二次電池に優れた電池特性（例えば、サイクル特性及び高温保存特性など）を発揮させ得る電極合材層を形成することができる。
　なお、本発明のＣＮＴ分散液は、上述したＣＮＴ、所定の重合体、及び分散媒以外の成分（その他の成分）を更に含んでいてもよいが、通常、電極活物質を含有していない。 (CNT dispersion)
The CNT dispersion liquid of the present invention contains CNTs, a predetermined polymer, and a dispersion medium, and is characterized in that the rate of change in specific absorbance before and after a predetermined centrifugal treatment is less than a predetermined value. The CNT dispersion liquid of the present invention has excellent CNT dispersibility. Therefore, according to the slurry composition prepared using the CNT dispersion of the present invention, an electrode mixture layer that can exhibit excellent battery characteristics (e.g., cycle characteristics, high-temperature storage characteristics, etc.) in a secondary battery can be formed. be able to.
The CNT dispersion of the present invention may further contain components (other components) other than the above-mentioned CNTs, a predetermined polymer, and a dispersion medium, but usually does not contain an electrode active material.
＜遠心処理前後の比吸光度の変化率ΔＥ＞
　本発明のＣＮＴ分散液においては、ＣＮＴ分散液の比吸光度をＥ１とし、ＣＮＴ分散液を４０００ｒｐｍで１分間遠心処理して得られる上澄み液の比吸光度をＥ２とした場合に、式：ΔＥ＝１００×（Ｅ１－Ｅ２）／Ｅ１［％］により得られる遠心処理前後の比吸光度の変化率ΔＥが５０％未満であることが必要である。比吸光度の変化率ΔＥが５０％未満であれば、ＣＮＴ分散液の分散性を十分に向上させることができる。
　そして、上記比吸光度の変化率ΔＥは、４０％以下であることが好ましく、３５％以下であることがより好ましく、３０％以下であることが更に好ましく、２５％以下であることが一層好ましく、２３％以下であることがより一層好ましい。比吸光度の変化率ΔＥが上記上限以下であれば、ＣＮＴ分散液中のＣＮＴの分散性を更に向上させることができる。
　また、上記比吸光度の変化率ΔＥの下限は、特に限定されないが、例えば、０％以上であってもよいし、１％以上であってもよいし、５％以上であってもよい。
　なお、上記比吸光度の変化率ΔＥの値は、例えば、ＣＮＴ分散液に含まれる重合体の組成及び性状、並びに、ＣＮＴ分散液の製造の際の分散処理機及び分散処理の条件等により制御することができる。 <Change rate ΔE of specific absorbance before and after centrifugation treatment>
In the CNT dispersion of the present invention, when the specific absorbance of the CNT dispersion is E1 and the specific absorbance of the supernatant obtained by centrifuging the CNT dispersion at 4000 rpm for 1 minute is E2, the formula: ΔE=100 It is necessary that the rate of change ΔE in specific absorbance before and after centrifugation, obtained by ×(E1-E2)/E1 [%], is less than 50%. If the rate of change in specific absorbance ΔE is less than 50%, the dispersibility of the CNT dispersion can be sufficiently improved.
The rate of change in specific absorbance ΔE is preferably 40% or less, more preferably 35% or less, even more preferably 30% or less, even more preferably 25% or less, It is even more preferable that it is 23% or less. If the rate of change in specific absorbance ΔE is below the above upper limit, the dispersibility of CNTs in the CNT dispersion can be further improved.
Further, the lower limit of the rate of change in specific absorbance ΔE is not particularly limited, and may be, for example, 0% or more, 1% or more, or 5% or more.
Note that the value of the rate of change in specific absorbance ΔE is controlled, for example, by the composition and properties of the polymer contained in the CNT dispersion, the conditions of the dispersion processing machine and dispersion treatment during the production of the CNT dispersion, etc. be able to.
＜ＣＮＴ＞
　ＣＮＴは、ＣＮＴ分散液を含むスラリー組成物を用いて形成した電極合材層において、電極活物質同士の電気的接触を促進する導電材として機能し得る材料である。 <CNT>
CNT is a material that can function as a conductive material that promotes electrical contact between electrode active materials in an electrode composite material layer formed using a slurry composition containing a CNT dispersion.
　ＣＮＴとしては、単層ＣＮＴ及び多層ＣＮＴのいずれを用いることもできる。
　ＣＮＴの平均直径は、３ｎｍ以上２０ｎｍ以下であることが好ましい。ＣＮＴの平均直径が上記所定の範囲内であれば、ＣＮＴの分散性を十分に高く確保することができる。
　ＣＮＴの平均長さは、５μｍ以上３０μｍ以下であることが好ましい。ＣＮＴの平均長さが上記所定の範囲内であれば、ＣＮＴの分散性を十分に高く確保しつつ、ＣＮＴ分散液を含むスラリー組成物を用いて形成した電極合材層を備える二次電池のサイクル特性を向上させることができる。
　なお、本発明において、ＣＮＴの平均直径及び平均長さは、走査型電子顕微鏡（ＳＥＭ）を用いた観察により得られる画像から無作為に１００本のＣＮＴを選択して直径（外径）及び長さを計測し、当該１００本のＣＮＴの直径（外径）及び長さのそれぞれの平均値を求めることにより、測定することができる。 As the CNTs, either single-walled CNTs or multi-walled CNTs can be used.
The average diameter of the CNTs is preferably 3 nm or more and 20 nm or less. If the average diameter of the CNTs is within the above-mentioned predetermined range, the dispersibility of the CNTs can be ensured to be sufficiently high.
The average length of the CNTs is preferably 5 μm or more and 30 μm or less. If the average length of the CNTs is within the above predetermined range, the dispersibility of the CNTs can be ensured sufficiently high while a secondary battery including an electrode mixture layer formed using a slurry composition containing a CNT dispersion liquid can be produced. Cycle characteristics can be improved.
In the present invention, the average diameter and average length of CNTs are determined by randomly selecting 100 CNTs from images obtained by observation using a scanning electron microscope (SEM). It can be measured by measuring the diameter and finding the average value of the diameter (outer diameter) and length of the 100 CNTs.
　そして、ＣＮＴのＢＥＴ比表面積は、好ましくは１００ｍ2／ｇ以上、より好ましくは１５０ｍ2／ｇ以上であり、通常、２５００ｍ2／ｇ以下である。ＣＮＴのＢＥＴ比表面積が上記下限以上であれば、重合体との相互作用が良好に生じて、得られる二次電池の高温保存特性を高めることができる。これにより、電極合材層中において良好な導電パスを形成し、二次電池の出力特性を向上させることができる。また、ＣＮＴのＢＥＴ比表面積が上記上限以下であれば、ＣＮＴの凝集を抑制して、ＣＮＴの分散性を十分に高く確保することができる。 The BET specific surface area of the CNT is preferably 100 m 2 /g or more, more preferably 150 m 2 /g or more, and usually 2500 m 2 /g or less. If the BET specific surface area of the CNT is equal to or larger than the above-mentioned lower limit, interaction with the polymer will occur favorably, and the high-temperature storage characteristics of the obtained secondary battery can be improved. Thereby, a good conductive path can be formed in the electrode mixture layer, and the output characteristics of the secondary battery can be improved. Further, if the BET specific surface area of the CNTs is below the above upper limit, aggregation of the CNTs can be suppressed and a sufficiently high dispersibility of the CNTs can be ensured.
　なお、通常、ＣＮＴは、凝集し易く分散させ難い。しかし、本発明のＣＮＴ分散液では、上述した遠心処理前後の比吸光度の変化率が所定値未満であるため、ＣＮＴを良好かつ安定的に分散させることができる。 Note that normally, CNTs tend to aggregate and are difficult to disperse. However, in the CNT dispersion liquid of the present invention, since the rate of change in specific absorbance before and after the above-mentioned centrifugation treatment is less than the predetermined value, CNTs can be dispersed well and stably.
＜重合体＞
　重合体は、ＣＮＴ分散液中において導電材としてのＣＮＴを良好に分散させ得る成分である。また、重合体は、電極合材層に含まれる成分が電極合材層から脱離しないように保持する機能も発揮し得る成分である。 <Polymer>
The polymer is a component capable of favorably dispersing CNTs as a conductive material in a CNT dispersion liquid. Further, the polymer is a component that can also exhibit the function of holding components contained in the electrode composite material layer so that they do not separate from the electrode composite material layer.
＜＜重合体の組成＞＞
　重合体は、ニトリル基含有単量体単位と、アルキレン構造単位と、親水性基含有単量体とを含むことを必要とする。さらに、重合体は、任意で、ニトリル基含有単量体単位、アルキレン構造単位、及び親水性基含有単量体単位以外の繰り返し単位を更に含んでいてもよい。 <<Polymer composition>>
The polymer needs to contain a nitrile group-containing monomer unit, an alkylene structural unit, and a hydrophilic group-containing monomer. Furthermore, the polymer may optionally further contain repeating units other than the nitrile group-containing monomer unit, the alkylene structural unit, and the hydrophilic group-containing monomer unit.
［ニトリル基含有単量体単位］
　ニトリル基含有単量体単位は、ニトリル基含有単量体単位由来の繰り返し単位である。そして、ニトリル基含有単量体単位を形成し得るニトリル基含有単量体としては、α，β－エチレン性不飽和ニトリル単量体が挙げられる。そして、α，β－エチレン性不飽和ニトリル単量体としては、ニトリル基を有するα，β－エチレン性不飽和化合物であれば特に限定されないが、例えば、アクリロニトリル；α－クロロアクリロニトリル、α－ブロモアクリロニトリルなどのα－ハロゲノアクリロニトリル；メタクリロニトリル、α－エチルアクリロニトリルなどのα－アルキルアクリロニトリル；などが挙げられる。これらの中でも、ニトリル基含有単量体としては、アクリロニトリル及びメタクリロニトリルが好ましく、アクリロニトリルがより好ましい。
　これらは１種単独で、又は、２種以上を組み合わせて用いることができる。 [Nitrile group-containing monomer unit]
The nitrile group-containing monomer unit is a repeating unit derived from a nitrile group-containing monomer unit. Examples of the nitrile group-containing monomer that can form the nitrile group-containing monomer unit include α,β-ethylenically unsaturated nitrile monomers. The α,β-ethylenically unsaturated nitrile monomer is not particularly limited as long as it is an α,β-ethylenically unsaturated compound having a nitrile group, but examples include acrylonitrile; α-chloroacrylonitrile, α-bromo Examples thereof include α-halogenoacrylonitrile such as acrylonitrile; α-alkylacrylonitrile such as methacrylonitrile and α-ethyl acrylonitrile; and the like. Among these, as the nitrile group-containing monomer, acrylonitrile and methacrylonitrile are preferred, and acrylonitrile is more preferred.
These can be used alone or in combination of two or more.
　そして、重合体中におけるニトリル基含有単量体単位の含有割合は、重合体中の全繰り返し単位（構造単位と単量体単位との合計）を１００質量％とした場合に、１０質量％以上であることが好ましく、２０質量％以上であることがより好ましく、２５質量％以上であることが更に好ましく、３０質量％以上であることが一層好ましく、５５質量％以下であることが好ましく、４０質量％以下であることがより好ましい。重合体中におけるニトリル基含有単量体単位の含有割合が上記所定の範囲内であれば、ＣＮＴ分散液中のＣＮＴの分散性を更に向上させることができる。 The content of the nitrile group-containing monomer unit in the polymer is 10% by mass or more when the total repeating units (the sum of structural units and monomer units) in the polymer are 100% by mass. It is preferably 20% by mass or more, more preferably 25% by mass or more, even more preferably 30% by mass or more, preferably 55% by mass or less, 40% by mass or more. It is more preferable that it is less than % by mass. If the content of the nitrile group-containing monomer unit in the polymer is within the above-mentioned predetermined range, the dispersibility of CNTs in the CNT dispersion can be further improved.
［アルキレン構造単位］
　アルキレン構造単位は、一般式：－ＣｎＨ２ｎ－［但し、ｎは２以上の整数］で表わされるアルキレン構造のみで構成される繰り返し単位である。重合体がアルキレン構造単位を含むことにより、ＣＮＴ分散液中のＣＮＴの分散性を向上させることができる。 [Alkylene structural unit]
The alkylene structural unit is a repeating unit composed only of an alkylene structure represented by the general formula: -C n H 2n - [where n is an integer of 2 or more]. When the polymer contains an alkylene structural unit, the dispersibility of CNTs in the CNT dispersion can be improved.
　アルキレン構造単位は、直鎖状であっても分岐状であってもよいが、ＣＮＴ分散液中のＣＮＴの分散性を更に向上させる観点から、アルキレン構造単位は直鎖状、すなわち直鎖アルキレン構造単位であることが好ましい。また、アルキレン構造単位の炭素数は４以上である（即ち、上述した一般式－ＣｎＨ２ｎ－のｎが４以上の整数である）ことが好ましい。 The alkylene structural unit may be linear or branched, but from the viewpoint of further improving the dispersibility of CNTs in the CNT dispersion, the alkylene structural unit is linear, that is, a linear alkylene structure. Preferably, it is a unit. Further, the number of carbon atoms in the alkylene structural unit is preferably 4 or more (that is, n in the above-mentioned general formula -C n H 2n - is an integer of 4 or more).
　そして、重合体へのアルキレン構造単位の導入方法は、特に限定はされないが、例えば以下の（１）又は（２）の方法：
（１）共役ジエン単量体を含む単量体組成物から重合体を調製し、当該重合体に水素化（水素添加）することで、共役ジエン単量体単位をアルキレン構造単位に変換する方法
（２）１－オレフィン単量体を含む単量体組成物から重合体を調製する方法
が挙げられる。これらの中でも、（１）の方法が重合体の製造が容易であり好ましい。 The method of introducing the alkylene structural unit into the polymer is not particularly limited, but for example, the following method (1) or (2):
(1) A method of converting conjugated diene monomer units into alkylene structural units by preparing a polymer from a monomer composition containing a conjugated diene monomer and hydrogenating (hydrogenating) the polymer. (2) A method of preparing a polymer from a monomer composition containing a 1-olefin monomer can be mentioned. Among these, method (1) is preferred because it allows easy production of the polymer.
　すなわち、アルキレン構造単位は、共役ジエン単量体単位を水素化（水素添加）して得られる構造単位（共役ジエン水素化物単位）であることが好ましく、１,３－ブタジエン単位を水素化して得られる構造単位（１,３－ブタジエン水素化物単位）であることがより好ましい。
　また、１－オレフィン単量体としては、例えば、１－ブテン、１－ヘキセンなどが挙げられる。
　これらの共役ジエン単量体や１－オレフィン単量体は、単独で、又は、２種以上を組み合わせて用いることができる。 That is, the alkylene structural unit is preferably a structural unit (conjugated diene hydride unit) obtained by hydrogenating a conjugated diene monomer unit, and is preferably a structural unit obtained by hydrogenating a 1,3-butadiene unit. The structural unit (1,3-butadiene hydride unit) is more preferable.
Examples of the 1-olefin monomer include 1-butene and 1-hexene.
These conjugated diene monomers and 1-olefin monomers can be used alone or in combination of two or more.
　なお、上記（１）の方法に用い得る共役ジエン単量体としては、例えば、１，３－ブタジエン、イソプレン、２，３－ジメチル－１，３－ブタジエン、１，３－ペンタジエンなどの共役ジエン化合物が挙げられる。中でも、１，３－ブタジエンが好ましい。すなわち、アルキレン構造単位は、共役ジエン単量体単位を水素化して得られる構造単位（共役ジエン水素化物単位）であることが好ましく、１,３－ブタジエン単位を水素化して得られる構造単位（１,３－ブタジエン水素化物単位）であることがより好ましい。そして、水素化は、後述するような公知の方法を用いて行なうことができる。 The conjugated diene monomers that can be used in the method (1) above include, for example, conjugated dienes such as 1,3-butadiene, isoprene, 2,3-dimethyl-1,3-butadiene, and 1,3-pentadiene. Examples include compounds. Among them, 1,3-butadiene is preferred. That is, the alkylene structural unit is preferably a structural unit obtained by hydrogenating a conjugated diene monomer unit (conjugated diene hydride unit), and a structural unit obtained by hydrogenating a 1,3-butadiene unit (1 , 3-butadiene hydride unit). The hydrogenation can be carried out using a known method as described below.
　なお、上記（１）の方法を経て重合体にアルキレン構造単位を導入した場合に、共役ジエン単量体単位が完全に水素化がなされなかった場合には、重合体中に共役ジエン単量体単位が残留し得る。換言すると、重合体は、任意で、繰り返し単位として共役ジエン単量体単位を含有していてもよい。 In addition, when the alkylene structural unit is introduced into the polymer through the method (1) above, if the conjugated diene monomer unit is not completely hydrogenated, the conjugated diene monomer unit will not be completely hydrogenated in the polymer. Units may remain. In other words, the polymer may optionally contain conjugated diene monomer units as repeating units.
　重合体中におけるアルキレン構造単位及び共役ジエン単量体単位の合計含有割合は、重合体中の全繰り返し単位（構造単位と単量体単位との合計）を１００質量％とした場合に、３０質量％以上であることが好ましく、５０質量％以上であることがより好ましく、５５質量％以上であることが更に好ましく、６０質量％以上であることが一層好ましく、８０質量％以下であることが好ましく、７５質量％以下であることがより好ましく、７０質量％以下であることが更に好ましい。重合体中におけるアルキレン構造単位及び共役ジエン単量体単位の合計含有割合が上記所定の範囲内であれば、ＣＮＴ分散液中のＣＮＴの分散性を更に向上させることができる。 The total content of alkylene structural units and conjugated diene monomer units in the polymer is 30% by mass when all repeating units (total of structural units and monomer units) in the polymer are 100% by mass. % or more, more preferably 50% by mass or more, even more preferably 55% by mass or more, even more preferably 60% by mass or more, and preferably 80% by mass or less. , more preferably 75% by mass or less, and even more preferably 70% by mass or less. If the total content of alkylene structural units and conjugated diene monomer units in the polymer is within the above-mentioned predetermined range, the dispersibility of CNTs in the CNT dispersion can be further improved.
　なお、重合体が共役ジエン単量体単位を含まない場合、例えば、上記（１）の方法において共役ジエン単量体単位が完全に水素化された場合、又は、上記（２）の方法により重合体を製造した場合、重合体中におけるアルキレン構造単位の含有割合は、重合体中の全繰り返し単位（構造単位と単量体単位との合計）を１００質量％とした場合に、３０質量％以上であることが好ましく、５０質量％以上であることがより好ましく、６０質量％以上であることが更に好ましく、８０質量％以下であることが好ましく、７５質量％以下であることがより好ましく、７０質量％以下であることが更に好ましい。重合体中におけるアルキレン構造単位の含有割合が上記所定の範囲内であれば、ＣＮＴ分散液中のＣＮＴの分散性を更に向上させることができる。 In addition, when the polymer does not contain a conjugated diene monomer unit, for example, when the conjugated diene monomer unit is completely hydrogenated in the method (1) above, or when the polymer is hydrogenated by the method (2) above, When a polymer is produced, the content of alkylene structural units in the polymer is 30% by mass or more when the total repeating units (total of structural units and monomer units) in the polymer is 100% by mass. It is preferably 50% by mass or more, more preferably 60% by mass or more, preferably 80% by mass or less, more preferably 75% by mass or less, and 70% by mass or less. It is more preferably less than % by mass. If the content ratio of alkylene structural units in the polymer is within the above-mentioned predetermined range, the dispersibility of CNTs in the CNT dispersion can be further improved.
［親水性基含有単量体単位］
　親水性基含有単量体単位は、親水性基含有単量体由来の繰り返し単位である。
　親水性基含有単量体単位を形成し得る親水性基含有単量体としては、カルボン酸基を有する単量体、スルホン酸基を有する単量体、リン酸基を有する単量体、水酸基を有する単量体が挙げられる。 [Hydrophilic group-containing monomer unit]
The hydrophilic group-containing monomer unit is a repeating unit derived from a hydrophilic group-containing monomer.
Hydrophilic group-containing monomers that can form hydrophilic group-containing monomer units include monomers having a carboxylic acid group, monomers having a sulfonic acid group, monomers having a phosphoric acid group, and monomers having a hydroxyl group. Examples include monomers having the following.
　カルボン酸基を有する単量体としては、モノカルボン酸及びその誘導体や、ジカルボン酸及びその酸無水物並びにそれらの誘導体などが挙げられる。
　モノカルボン酸としては、アクリル酸、メタクリル酸、クロトン酸などが挙げられる。
　モノカルボン酸誘導体としては、２－エチルアクリル酸、イソクロトン酸、α－アセトキシアクリル酸、β－ｔｒａｎｓ－アリールオキシアクリル酸、α－クロロ－β－Ｅ－メトキシアクリル酸、β－ジアミノアクリル酸などが挙げられる。
　ジカルボン酸としては、マレイン酸、フマル酸、イタコン酸などが挙げられる。
　ジカルボン酸誘導体としては、メチルマレイン酸、ジメチルマレイン酸、フェニルマレイン酸、クロロマレイン酸、ジクロロマレイン酸、フルオロマレイン酸や、マレイン酸メチルアリル、マレイン酸ジフェニル、マレイン酸ノニル、マレイン酸デシル、マレイン酸ドデシル、マレイン酸オクタデシル、マレイン酸フルオロアルキルなどのマレイン酸エステルが挙げられる。
　ジカルボン酸の酸無水物としては、無水マレイン酸、アクリル酸無水物、メチル無水マレイン酸、ジメチル無水マレイン酸などが挙げられる。
　また、カルボン酸基を有する単量体としては、加水分解によりカルボキシル基を生成する酸無水物も使用できる。
　その他、マレイン酸モノエチル、マレイン酸ジエチル、マレイン酸モノブチル、マレイン酸ジブチル、フマル酸モノエチル、フマル酸ジエチル、フマル酸モノブチル、フマル酸ジブチル、フマル酸モノシクロヘキシル、フマル酸ジシクロヘキシル、イタコン酸モノエチル、イタコン酸ジエチル、イタコン酸モノブチル、イタコン酸ジブチルなどのα，β－エチレン性不飽和多価カルボン酸のモノエステル及びジエステルも挙げられる。 Examples of the monomer having a carboxylic acid group include monocarboxylic acids and derivatives thereof, dicarboxylic acids and anhydrides thereof, and derivatives thereof.
Examples of monocarboxylic acids include acrylic acid, methacrylic acid, and crotonic acid.
Examples of monocarboxylic acid derivatives include 2-ethyl acrylic acid, isocrotonic acid, α-acetoxyacrylic acid, β-trans-aryloxyacrylic acid, α-chloro-β-E-methoxyacrylic acid, β-diaminoacrylic acid, etc. Can be mentioned.
Examples of dicarboxylic acids include maleic acid, fumaric acid, and itaconic acid.
Examples of dicarboxylic acid derivatives include methylmaleic acid, dimethylmaleic acid, phenylmaleic acid, chloromaleic acid, dichloromaleic acid, fluoromaleic acid, methylallyl maleate, diphenyl maleate, nonyl maleate, decyl maleate, and dodecyl maleate. , octadecyl maleate, fluoroalkyl maleate, and other maleic acid esters.
Examples of acid anhydrides of dicarboxylic acids include maleic anhydride, acrylic anhydride, methylmaleic anhydride, dimethylmaleic anhydride, and the like.
Furthermore, as the monomer having a carboxylic acid group, an acid anhydride that generates a carboxyl group by hydrolysis can also be used.
Others: monoethyl maleate, diethyl maleate, monobutyl maleate, dibutyl maleate, monoethyl fumarate, diethyl fumarate, monobutyl fumarate, dibutyl fumarate, monocyclohexyl fumarate, dicyclohexyl fumarate, monoethyl itaconate, diethyl itaconate Also included are monoesters and diesters of α,β-ethylenically unsaturated polycarboxylic acids such as monobutyl itaconate, dibutyl itaconate, and the like.
　スルホン酸基を有する単量体としては、ビニルスルホン酸、メチルビニルスルホン酸、（メタ）アリルスルホン酸、スチレンスルホン酸、（メタ）アクリル酸－２－スルホン酸エチル、２－アクリルアミド－２－メチルプロパンスルホン酸、３－アリロキシ－２－ヒドロキシプロパンスルホン酸などが挙げられる。
　なお、本発明において「（メタ）アリル」とは、アリル及び／又はメタリルを意味する。 Examples of monomers having a sulfonic acid group include vinylsulfonic acid, methylvinylsulfonic acid, (meth)allylsulfonic acid, styrenesulfonic acid, ethyl (meth)acrylate-2-sulfonate, and 2-acrylamide-2-methyl. Examples include propanesulfonic acid and 3-allyloxy-2-hydroxypropanesulfonic acid.
In the present invention, "(meth)allyl" means allyl and/or methallyl.
　リン酸基を有する単量体としては、リン酸－２－（メタ）アクリロイルオキシエチル、リン酸メチル－２－（メタ）アクリロイルオキシエチル、リン酸エチル－（メタ）アクリロイルオキシエチル、ビニルホスホン酸、ビニルホスホン酸ジメチルなどが挙げられる。
　なお、本発明において「（メタ）アクリロイル」とは、アクリロイル及び／又はメタクリロイルを意味する。 Monomers having a phosphoric acid group include 2-(meth)acryloyloxyethyl phosphate, methyl-2-(meth)acryloyloxyethyl phosphate, ethyl-(meth)acryloyloxyethyl phosphate, and vinylphosphonic acid. , dimethyl vinylphosphonate, and the like.
In the present invention, "(meth)acryloyl" means acryloyl and/or methacryloyl.
　水酸基を有する単量体としては、（メタ）アリルアルコール、３－ブテン－１－オール、５－ヘキセン－１－オールなどのエチレン性不飽和アルコール；アクリル酸－２－ヒドロキシエチル、アクリル酸－２－ヒドロキシプロピル、メタクリル酸－２－ヒドロキシエチル、メタクリル酸－２－ヒドロキシプロピル、マレイン酸ジ－２－ヒドロキシエチル、マレイン酸ジ－４－ヒドロキシブチル、イタコン酸ジ－２－ヒドロキシプロピルなどのエチレン性不飽和カルボン酸のアルカノールエステル類；一般式：ＣＨ２＝ＣＲ１－ＣＯＯ－（ＣｎＨ２ｎＯ）ｍ－Ｈ（式中、ｍは２～９の整数、ｎは２～４の整数、Ｒ１は水素又はメチル基を表す）で表されるポリアルキレングリコールと（メタ）アクリル酸とのエステル類；２－ヒドロキシエチル－２’－（メタ）アクリロイルオキシフタレート、２－ヒドロキシエチル－２’－（メタ）アクリロイルオキシサクシネートなどのジカルボン酸のジヒドロキシエステルのモノ（メタ）アクリル酸エステル類；２－ヒドロキシエチルビニルエーテル、２－ヒドロキシプロピルビニルエーテルなどのビニルエーテル類；（メタ）アリル－２－ヒドロキシエチルエーテル、（メタ）アリル－２－ヒドロキシプロピルエーテル、（メタ）アリル－３－ヒドロキシプロピルエーテル、（メタ）アリル－２－ヒドロキシブチルエーテル、（メタ）アリル－３－ヒドロキシブチルエーテル、（メタ）アリル－４－ヒドロキシブチルエーテル、（メタ）アリル－６－ヒドロキシヘキシルエーテルなどのアルキレングリコールのモノ（メタ）アリルエーテル類；ジエチレングリコールモノ（メタ）アリルエーテル、ジプロピレングリコールモノ（メタ）アリルエーテルなどのポリオキシアルキレングリコールモノ（メタ）アリルエーテル類；グリセリンモノ（メタ）アリルエーテル、（メタ）アリル－２－クロロ－３－ヒドロキシプロピルエーテル、（メタ）アリル－２－ヒドロキシ－３－クロロプロピルエーテルなどの、（ポリ）アルキレングリコールのハロゲン及びヒドロキシ置換体のモノ（メタ）アリルエーテル；オイゲノール、イソオイゲノールなどの多価フェノールのモノ（メタ）アリルエーテル及びそのハロゲン置換体；（メタ）アリル－２－ヒドロキシエチルチオエーテル、（メタ）アリル－２－ヒドロキシプロピルチオエーテルなどのアルキレングリコールの（メタ）アリルチオエーテル類；などが挙げられる。 Examples of monomers having a hydroxyl group include ethylenically unsaturated alcohols such as (meth)allyl alcohol, 3-buten-1-ol, and 5-hexen-1-ol; 2-hydroxyethyl acrylate, and 2-hydroxyethyl acrylate; -Ethylenic compounds such as hydroxypropyl, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, di-2-hydroxyethyl maleate, di-4-hydroxybutyl maleate, di-2-hydroxypropyl itaconate, etc. Alkanol esters of unsaturated carboxylic acids; general formula: CH 2 = CR 1 -COO-(C n H 2n O) m -H (wherein m is an integer of 2 to 9, n is an integer of 2 to 4, Esters of polyalkylene glycol (R 1 represents hydrogen or methyl group) and (meth)acrylic acid; 2-hydroxyethyl-2'-(meth)acryloyloxyphthalate, 2-hydroxyethyl-2' - Mono(meth)acrylic acid esters of dihydroxy esters of dicarboxylic acids such as (meth)acryloyloxysuccinate; Vinyl ethers such as 2-hydroxyethyl vinyl ether and 2-hydroxypropyl vinyl ether; (meth)allyl-2-hydroxyethyl Ether, (meth)allyl-2-hydroxypropyl ether, (meth)allyl-3-hydroxypropyl ether, (meth)allyl-2-hydroxybutyl ether, (meth)allyl-3-hydroxybutyl ether, (meth)allyl-4 - Mono(meth)allyl ethers of alkylene glycols such as hydroxybutyl ether and (meth)allyl-6-hydroxyhexyl ether; polyoxyalkylene glycols such as diethylene glycol mono(meth)allyl ether and dipropylene glycol mono(meth)allyl ether Mono(meth)allyl ethers; ) Mono(meth)allyl ether of halogen- and hydroxy-substituted alkylene glycol; mono(meth)allyl ether of polyhydric phenol such as eugenol and isoeugenol and its halogen-substituted product; (meth)allyl-2-hydroxyethylthioether; Examples include (meth)allyl thioethers of alkylene glycol such as (meth)allyl-2-hydroxypropyl thioether.
　そして、ＣＮＴ分散液中のＣＮＴの分散性を更に向上させる観点から、親水性基含有単量体としては、カルボン酸基を有する単量体（カルボン酸基含有単量体）を用いることが好ましく、モノカルボン酸を用いることがより好ましく、メタクリル酸を用いることが更に好ましい。 From the viewpoint of further improving the dispersibility of CNTs in the CNT dispersion, it is preferable to use a monomer having a carboxylic acid group (carboxylic acid group-containing monomer) as the hydrophilic group-containing monomer. , it is more preferable to use monocarboxylic acid, and even more preferable to use methacrylic acid.
　重合体中における親水性基含有単量体単位の含有割合は、重合体中の全繰り返し単位（構造単位と単量体単位との合計）を１００質量％とした場合に、６．５質量％以上であることが好ましく、８質量％以上であることがより好ましく、９質量％以上であることが更に好ましく、１０質量％以上であることが一層好ましく、５０質量%以下であることが好ましく、３５質量％以下であることがより好ましく、２５質量％以下であることが更に好ましく、１５質量％以下であることが一層好ましい。重合体中における親水性基含有単量体単位の含有割合が上記下限以上であれば、重合体中に極性基である親水性基が十分に導入されることで、重合体の分子鎖の動きが柔軟になるためと推察されるが、重合体のＣＮＴに対する吸着量が増大し、ＣＮＴ分散液中のＣＮＴの分散性を更に向上させることができる。また、重合体中における親水性基含有単量体単位の含有割合が上記下限以上であれば、ＣＮＴ分散液を用いて調製したスラリー組成物から形成される電極合材層中において、重合体が水分を捕捉することで水分による充放電機能の阻害が生じ難くなるためと推察されるが、二次電池のサイクル特性及び高温保存特性を向上させることができる。重合体中における親水性基含有単量体単位の含有割合が上記上限以下であれば、ＣＮＴ分散液中のＣＮＴの分散性を更に向上させると共に、ＣＮＴ分散液の粘度安定性を向上させることができる。また、重合体中における親水性基含有単量体単位の含有割合が上記上限以下であれば、ＣＮＴ分散液を用いて調製したスラリー組成物から形成される電極合材層の接着性を高めると共に、当該電極合材層を備える二次電池の高温保存特性を向上させることができる。 The content ratio of the hydrophilic group-containing monomer unit in the polymer is 6.5% by mass when the total repeating units (total of structural units and monomer units) in the polymer are 100% by mass. It is preferably at least 8% by mass, more preferably at least 9% by mass, even more preferably at least 10% by mass, and preferably at most 50% by mass, It is more preferably 35% by mass or less, even more preferably 25% by mass or less, and even more preferably 15% by mass or less. If the content of hydrophilic group-containing monomer units in the polymer is equal to or higher than the above lower limit, sufficient hydrophilic groups, which are polar groups, will be introduced into the polymer, and the movement of the molecular chains of the polymer will be inhibited. This is presumed to be because the polymer becomes flexible, but the amount of adsorption of the polymer onto the CNTs increases, making it possible to further improve the dispersibility of the CNTs in the CNT dispersion. In addition, if the content ratio of the hydrophilic group-containing monomer unit in the polymer is equal to or higher than the above lower limit, the polymer will remain in the electrode composite material layer formed from the slurry composition prepared using the CNT dispersion. This is presumably because capturing moisture makes it difficult for the charging/discharging function to be inhibited by moisture, and it is possible to improve the cycle characteristics and high-temperature storage characteristics of the secondary battery. If the content of the hydrophilic group-containing monomer unit in the polymer is below the above upper limit, it is possible to further improve the dispersibility of CNTs in the CNT dispersion and to improve the viscosity stability of the CNT dispersion. can. In addition, if the content of the hydrophilic group-containing monomer unit in the polymer is below the above upper limit, the adhesion of the electrode composite layer formed from the slurry composition prepared using the CNT dispersion can be improved, and , the high-temperature storage characteristics of a secondary battery including the electrode mixture layer can be improved.
［その他の単量体単位］
　重合体は、繰り返し単位として、上述したニトリル基含有単量体単位、アルキレン構造単位、共役ジエン単量体単位、及び親水性基含有単量体単位以外の単量体単位（以下、「その他の単量体単位」と称する。）を更に含んでいてもよい。 [Other monomer units]
The polymer contains monomer units other than the above-mentioned nitrile group-containing monomer units, alkylene structural units, conjugated diene monomer units, and hydrophilic group-containing monomer units (hereinafter referred to as "other monomer units") as repeating units. (referred to as "monomeric units").
　重合体中におけるその他の単量体単位の含有割合は、重合体中の全繰り返し単位（構造単位と単量体単位との合計）を１００質量％とした場合に、５質量％以下であることが好ましく、４質量％以下であることがより好ましく、３質量％以下であることが更に好ましく、２質量％以下であることが一層好ましく、１質量％以下であることがより一層好ましい。重合体中におけるその他の単量体単位の含有割合が上記上限以下であれば、重合体のＣＮＴに対する吸着量が増大し、ＣＮＴ分散液中のＣＮＴの分散性を更に向上させると共に、ＣＮＴ分散液の粘度安定性を向上させることができる。また、重合体中におけるその他の単量体単位の含有割合が上記上限以下であれば、ＣＮＴ分散液を用いて調製したスラリー組成物から形成される電極合材層の接着性を高めることができる。さらに、重合体中におけるその他の単量体単位の含有割合が上記上限以下であれば、当該電極合材層を備える二次電池のサイクル特性及び高温保存特性を向上させることができる。
　また、重合体中におけるその他の単量体単位の含有割合の下限は、特に限定されず、例えば、０質量％以上とすることができる。そして、ＣＮＴ分散液中のＣＮＴの分散性を一層向上させる観点から、重合体中におけるその他の単量体単位の含有割合は、０質量％であることが特に好ましい。即ち、重合体は、ニトリル基含有単量体単位、アルキレン構造単位、共役ジエン単量体単位、及び親水性基含有単量体単位以外の単量体単位を含有しないことが特に好ましい。 The content ratio of other monomer units in the polymer shall be 5% by mass or less, when the total repeating units (total of structural units and monomer units) in the polymer are 100% by mass. It is preferably at most 4% by mass, more preferably at most 3% by mass, even more preferably at most 2% by mass, even more preferably at most 1% by mass. If the content of other monomer units in the polymer is below the above upper limit, the adsorption amount of the polymer to CNTs will increase, further improving the dispersibility of CNTs in the CNT dispersion, and improving the CNT dispersion. can improve the viscosity stability of In addition, if the content of other monomer units in the polymer is below the above upper limit, the adhesiveness of the electrode composite layer formed from the slurry composition prepared using the CNT dispersion can be improved. . Furthermore, if the content of other monomer units in the polymer is below the above upper limit, the cycle characteristics and high temperature storage characteristics of the secondary battery including the electrode composite layer can be improved.
Further, the lower limit of the content of other monomer units in the polymer is not particularly limited, and can be, for example, 0% by mass or more. From the viewpoint of further improving the dispersibility of CNTs in the CNT dispersion, the content of other monomer units in the polymer is particularly preferably 0% by mass. That is, it is particularly preferable that the polymer contains no monomer units other than nitrile group-containing monomer units, alkylene structural units, conjugated diene monomer units, and hydrophilic group-containing monomer units.
　その他の単量体単位を形成し得る単量体としては、特に限定されることはなく、例えば、（メタ）アクリル酸エステル単量体及び芳香族ビニル単量体などが挙げられる。
　なお、これらの単量体は一種単独で、又は、２種以上を組み合わせて用いることができる。 Monomers that can form other monomer units are not particularly limited, and examples thereof include (meth)acrylic acid ester monomers and aromatic vinyl monomers.
In addition, these monomers can be used individually or in combination of two or more types.
－（メタ）アクリル酸エステル単量体単位－
　（メタ）アクリル酸エステル単量体単位とは、（メタ）アクリル酸エステル単量体由来の繰り返し単位である。 -(meth)acrylic acid ester monomer unit-
The (meth)acrylic acid ester monomer unit is a repeating unit derived from a (meth)acrylic acid ester monomer.
　ここで、（メタ）アクリル酸エステル単量体としては、メチルアクリレート、エチルアクリレート、ｎ－プロピルアクリレート、イソプロピルアクリレート、ｎ－ブチルアクリレート、ｔ－ブチルアクリレート、イソブチルアクリレート、ｎ－ペンチルアクリレート、イソペンチルアクリレート、ヘキシルアクリレート、ヘプチルアクリレート、オクチルアクリレート、２－エチルヘキシルアクリレート、ノニルアクリレート、デシルアクリレート、ラウリルアクリレート、ｎ－テトラデシルアクリレート、ステアリルアクリレートなどのアクリル酸アルキルエステル；メチルメタクリレート、エチルメタクリレート、ｎ－プロピルメタクリレート、イソプロピルメタクリレート、ｎ－ブチルメタクリレート、ｔ－ブチルメタクリレート、イソブチルメタクリレート、ｎ－ペンチルメタクリレート、イソペンチルメタクリレート、ヘキシルメタクリレート、ヘプチルメタクリレート、オクチルメタクリレート、２－エチルヘキシルメタクリレート、ノニルメタクリレート、デシルメタクリレート、ラウリルメタクリレート、ｎ－テトラデシルメタクリレート、ステアリルメタクリレートなどのメタクリル酸アルキルエステル；などが挙げられる。 Here, as the (meth)acrylic acid ester monomer, methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, t-butyl acrylate, isobutyl acrylate, n-pentyl acrylate, isopentyl acrylate , hexyl acrylate, heptyl acrylate, octyl acrylate, 2-ethylhexyl acrylate, nonyl acrylate, decyl acrylate, lauryl acrylate, n-tetradecyl acrylate, stearyl acrylate, and other acrylic acid alkyl esters; methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, Isopropyl methacrylate, n-butyl methacrylate, t-butyl methacrylate, isobutyl methacrylate, n-pentyl methacrylate, isopentyl methacrylate, hexyl methacrylate, heptyl methacrylate, octyl methacrylate, 2-ethylhexyl methacrylate, nonyl methacrylate, decyl methacrylate, lauryl methacrylate, n- Examples include methacrylic acid alkyl esters such as tetradecyl methacrylate and stearyl methacrylate.
　重合体中における（メタ）アクリル酸エステル単量体単位の含有割合は、重合体中の全繰り返し単位（構造単位と単量体単位との合計）を１００質量％とした場合に、５質量％以下であることが好ましく、４質量％以下であることがより好ましく、３質量％以下であることが更に好ましく、２質量％以下であることが一層好ましく、１質量％以下であることがより一層好ましい。重合体中における（メタ）アクリル酸エステル単量体単位の含有割合が上記上限以下であれば、重合体のＣＮＴに対する吸着量が増大し、ＣＮＴ分散液中のＣＮＴの分散性を更に向上させると共に、ＣＮＴ分散液の粘度安定性を向上させることができる。また、重合体中における（メタ）アクリル酸エステル単量体単位の含有割合が上記上限以下であれば、ＣＮＴ分散液を用いて調製したスラリー組成物から形成される電極合材層の接着性を高めることができる。さらに、重合体中における（メタ）アクリル酸エステル単量体単位の含有割合が上記上限以下であれば、当該電極合材層を備える二次電池のサイクル特性及び高温保存特性を向上させることができる。
　また、重合体中における（メタ）アクリル酸エステル単量体単位の含有割合の下限は、特に限定されず、例えば、０質量％以上とすることができる。そして、ＣＮＴ分散液中のＣＮＴの分散性を一層向上させる観点から、重合体中における（メタ）アクリル酸エステル単量体単位の含有割合は、０質量％であることが特に好ましい。即ち、重合体は、（メタ）アクリル酸エステル単量体単位を含有しないことが特に好ましい。 The content ratio of (meth)acrylic acid ester monomer units in the polymer is 5% by mass when the total repeating units (total of structural units and monomer units) in the polymer is 100% by mass. It is preferably at most 4% by mass, more preferably at most 3% by mass, even more preferably at most 2% by mass, even more preferably at most 1% by mass. preferable. If the content of (meth)acrylic acid ester monomer units in the polymer is below the above upper limit, the adsorption amount of the polymer to CNTs will increase, further improving the dispersibility of CNTs in the CNT dispersion, and , the viscosity stability of the CNT dispersion can be improved. In addition, if the content of (meth)acrylic acid ester monomer units in the polymer is below the above upper limit, the adhesiveness of the electrode composite layer formed from the slurry composition prepared using the CNT dispersion may be reduced. can be increased. Furthermore, if the content of (meth)acrylic acid ester monomer units in the polymer is below the above upper limit, the cycle characteristics and high-temperature storage characteristics of the secondary battery including the electrode composite layer can be improved. .
Further, the lower limit of the content of (meth)acrylic acid ester monomer units in the polymer is not particularly limited, and can be, for example, 0% by mass or more. From the viewpoint of further improving the dispersibility of CNTs in the CNT dispersion, the content of (meth)acrylic acid ester monomer units in the polymer is particularly preferably 0% by mass. That is, it is particularly preferable that the polymer does not contain (meth)acrylic acid ester monomer units.
－芳香族ビニル単量体単位－
　芳香族ビニル単量体単位は、芳香族ビニル単量体由来の繰り返し単位である。ここで、芳香族ビニル単量体単位を形成し得る芳香族ビニル単量体としては、スチレン、α－メチルスチレン、ビニルトルエン、ジビニルベンゼンなどが挙げられる。これらは１種類を単独で、又は、２種類以上を組み合わせて用いることができる。 -Aromatic vinyl monomer unit-
Aromatic vinyl monomer units are repeating units derived from aromatic vinyl monomers. Here, examples of the aromatic vinyl monomer that can form aromatic vinyl monomer units include styrene, α-methylstyrene, vinyltoluene, divinylbenzene, and the like. These can be used alone or in combination of two or more.
　重合体中における芳香族ビニル単量体単位の含有割合は、重合体中の全繰り返し単位（構造単位と単量体単位との合計）を１００質量％とした場合に、５質量％以下であることが好ましく、４質量％以下であることがより好ましく、３質量％以下であることが更に好ましく、２質量％以下であることが一層好ましく、１質量％以下であることがより一層好ましい。重合体中における芳香族ビニル単量体単位の含有割合が上記上限以下であれば、重合体のＣＮＴに対する吸着量が増大し、ＣＮＴ分散液中のＣＮＴの分散性を更に向上させると共に、ＣＮＴ分散液の粘度安定性を向上させることができる。また、重合体中における芳香族ビニル単量体単位の含有割合が上記上限以下であれば、ＣＮＴ分散液を用いて調製したスラリー組成物から形成される電極合材層の接着性を高めることができる。さらに、重合体中における芳香族ビニル単量体単位の含有割合が上記上限以下であれば、当該電極合材層を備える二次電池のサイクル特性及び高温保存特性を向上させることができる。
　また、重合体中における芳香族ビニル単量体単位の含有割合の下限は、特に限定されず、例えば、０質量％以上とすることができる。そして、ＣＮＴ分散液中のＣＮＴの分散性を一層向上させる観点から、重合体中における芳香族ビニル単量体単位の含有割合は、０質量％であることが特に好ましい。即ち、重合体は、芳香族ビニル単量体単位を含有しないことが特に好ましい。 The content ratio of aromatic vinyl monomer units in the polymer is 5% by mass or less when the total repeating units (total of structural units and monomer units) in the polymer are 100% by mass. It is preferably at most 4% by mass, more preferably at most 3% by mass, even more preferably at most 2% by mass, and even more preferably at most 1% by mass. If the content of aromatic vinyl monomer units in the polymer is below the above upper limit, the adsorption amount of the polymer to CNTs will increase, further improving the dispersibility of CNTs in the CNT dispersion liquid, and improving CNT dispersion. The viscosity stability of the liquid can be improved. Furthermore, if the content of aromatic vinyl monomer units in the polymer is below the above upper limit, it is possible to improve the adhesion of the electrode composite layer formed from the slurry composition prepared using the CNT dispersion. can. Furthermore, if the content of the aromatic vinyl monomer unit in the polymer is below the above upper limit, the cycle characteristics and high temperature storage characteristics of the secondary battery including the electrode composite layer can be improved.
Further, the lower limit of the content of aromatic vinyl monomer units in the polymer is not particularly limited, and can be, for example, 0% by mass or more. From the viewpoint of further improving the dispersibility of CNTs in the CNT dispersion, the content of aromatic vinyl monomer units in the polymer is particularly preferably 0% by mass. That is, it is particularly preferable that the polymer does not contain aromatic vinyl monomer units.
＜＜重合体の調製方法＞＞
　なお、上述した重合体の製造方法は特に限定はされず、例えば、溶液重合法、懸濁重合法、塊状重合法、乳化重合法などのいずれの方法も用いることができる。
　また、重合方法としては、イオン重合、ラジカル重合、リビングラジカル重合などの付加重合を用いることができる。また、重合開始剤としては、既知の重合開始剤を用いることができる。 <<Preparation method of polymer>>
The method for producing the above-described polymer is not particularly limited, and any method such as solution polymerization, suspension polymerization, bulk polymerization, emulsion polymerization, etc. can be used.
Further, as the polymerization method, addition polymerization such as ionic polymerization, radical polymerization, and living radical polymerization can be used. Furthermore, known polymerization initiators can be used as the polymerization initiator.
　そして、重合にあたり、メルカプト基などの硫黄含有基を有する分子量調整剤を用いることが好ましい。分子量調整剤としての、メルカプト基を有する化合物としては、例えば、オクチルメルカプタン、２，２，４，６，６－ペンタメチル－４－ヘプタンチオール、２，４，４，６，６－ペンタメチル－２－ヘプタンチオール、２，３，４，６，６－ペンタメチル－２－ヘプタンチオール、２，３，４，６，６－ペンタメチル－３－ヘプタンチオール、ｔ－ドデシルメルカプタン、ｎ-ドデシルメルカプタン、などの炭素数８～１２のメルカプト基を有する化合物；２，２，４，６，６－ペンタメチル－４－オクタンチオール、２，２，４，６，６，８，８－ヘプタメチル－４－ノナンチオール、ビス(２－メルカプトエチル)スルフィド、３－メルカプトプロピオン酸メチル、１－ブタンチオールなどのメルカプト基を有する化合物が挙げられる。なかでも、炭素数８～１２のメルカプト基を有する化合物が好ましく、ｔ－ドデシルメルカプタンがより好ましい。
　そして、分子量調整剤としてのメルカプト基を有する化合物の配合量は、好ましくは得られる重合体の８質量％水溶液（ｐＨ８．０以上）のヘイズが後述する所定値以下となるように、適宜調整することができる。 In the polymerization, it is preferable to use a molecular weight regulator having a sulfur-containing group such as a mercapto group. Examples of compounds having a mercapto group as molecular weight regulators include octylmercaptan, 2,2,4,6,6-pentamethyl-4-heptanethiol, 2,4,4,6,6-pentamethyl-2- Carbon atoms such as heptanethiol, 2,3,4,6,6-pentamethyl-2-heptanethiol, 2,3,4,6,6-pentamethyl-3-heptanethiol, t-dodecylmercaptan, n-dodecylmercaptan, etc. Compounds having 8 to 12 mercapto groups; 2,2,4,6,6-pentamethyl-4-octanethiol, 2,2,4,6,6,8,8-heptamethyl-4-nonanethiol, bis Examples include compounds having a mercapto group such as (2-mercaptoethyl) sulfide, methyl 3-mercaptopropionate, and 1-butanethiol. Among these, compounds having a mercapto group having 8 to 12 carbon atoms are preferred, and t-dodecylmercaptan is more preferred.
The amount of the compound having a mercapto group as a molecular weight regulator is preferably adjusted as appropriate so that the haze of the resulting 8% by mass aqueous solution (pH 8.0 or higher) of the polymer is equal to or less than a predetermined value described below. be able to.
　また、上述した重合体を上記（１）の方法で製造する場合には、水素添加される重合体の重合方法としては、鉄系化合物を含むレドックス重合開始剤を使用したラジカル重合を用いることが好ましく、レドックス重合開始剤としては、特に限定されることなく、例えばクメンハイドロパーオキサイドと、エチレンジアミン四酢酸モノナトリウム鉄と、ヒドロキシメタンスルフィン酸ナトリウムと、エチレンジアミン四酢酸四ナトリウム塩（ＥＤＴＡ・４Ｎａ）との組み合わせ等を用いることができる。 In addition, when producing the above-mentioned polymer by the method (1) above, radical polymerization using a redox polymerization initiator containing an iron-based compound may be used as the polymerization method for the polymer to be hydrogenated. Preferably, the redox polymerization initiator is not particularly limited, and includes, for example, cumene hydroperoxide, monosodium iron ethylenediaminetetraacetate, sodium hydroxymethanesulfinate, and tetrasodium ethylenediaminetetraacetic acid salt (EDTA.4Na). A combination of these can be used.
　上述した重合体を上記（１）の方法で製造する場合、乳化重合を行った後、得られた水素化前の重合体（即ち、重合体の前駆体）の水分散液に対して凝固剤を添加して凝固させ、水素化前の重合体を回収し、回収したものに対して（任意に、後述する「複分解反応」を実施した後に）水素化を行ってもよいが、乳化重合後に得られる水素化前の重合体の水分散液に対して、上述した凝固処理を行わず、そのまま水素化を行うことが好ましい。乳化重合により得られた水素化前の重合体の水分散液に対して、凝固処理を経由せずに、そのまま水素化を行うことにより、得られる水素化後の重合体の構造が良好に維持されるためと推察されるが、重合体の８質量％水溶液（ｐＨ８．０以上）のヘイズを後述する所定値以下に容易に調整することができ、当該重合体を用いて調製したＣＮＴ分散液中のＣＮＴの分散性を更に向上させることができる。 When producing the above-mentioned polymer by the method (1) above, after performing emulsion polymerization, a coagulant is added to the obtained aqueous dispersion of the polymer (i.e., the precursor of the polymer) before hydrogenation. may be added to coagulate, collect the polymer before hydrogenation, and hydrogenate the recovered material (optionally after carrying out the "metathesis reaction" described later), but after emulsion polymerization. It is preferable to directly hydrogenate the obtained aqueous dispersion of the polymer before hydrogenation without performing the above-mentioned coagulation treatment. By directly hydrogenating the aqueous dispersion of the polymer before hydrogenation obtained by emulsion polymerization without going through coagulation treatment, the structure of the resulting hydrogenated polymer is maintained well. This is presumed to be because the haze of an 8% by mass aqueous solution (pH 8.0 or higher) of the polymer can be easily adjusted to a predetermined value or less, which will be described later, and the CNT dispersion prepared using the polymer. The dispersibility of CNTs therein can be further improved.
　なお、水素化は、油層水素化法又は水層水素化法等の既知の水素化方法を用いて行うことができる。また、水素化に用いる触媒としては、公知の選択的水素化触媒であれば限定なく使用でき、パラジウム系触媒やロジウム系触媒を用いることができる。これらは２種以上併用してもよい。 Note that hydrogenation can be performed using a known hydrogenation method such as an oil layer hydrogenation method or an aqueous layer hydrogenation method. Further, as the catalyst used for hydrogenation, any known selective hydrogenation catalyst can be used without limitation, and palladium-based catalysts and rhodium-based catalysts can be used. Two or more of these may be used in combination.
　また、重合体の水素化は、例えば特許第４５０９７９２号に記載の方法を用いて行ってもよい。具体的には、重合体の水素化は、触媒及びコ（ｃｏ－）オレフィンの存在下において重合体の複分解反応を実施した後に行ってもよい。
　ここで、複分解反応の触媒としては、既知のルテニウム系触媒を用いることができる。中でも、複分解反応の触媒としては、二塩化ビス（トリシクロヘキシルホスフィン）ベンジリデンルテニウム、１,３－ビス（２,４,６－トリメチルフェニル）－２－（イミダゾリジニリデン）（ジクロロフェニルメチレン）（トリシクロへキシルホスフィン）ルテニウムなどのＧｒｕｂｂｓ触媒を用いることが好ましい。また、コオレフィンとしては、エチレン、イソブタン、１－ヘキサンなどの炭素数２～１６のオレフィンを用いることができる。また、複分解反応後に水素化を行う際の水素化触媒としては、例えばＷｉｌｋｉｎｓｏｎ触媒（（ＰＰｈ３）３ＲｈＣｌ）等の既知の均質水素化触媒を用いることができる。 Further, hydrogenation of the polymer may be performed using the method described in, for example, Japanese Patent No. 4509792. Specifically, hydrogenation of the polymer may be performed after carrying out a metathesis reaction of the polymer in the presence of a catalyst and a co-olefin.
Here, a known ruthenium-based catalyst can be used as a catalyst for the metathesis reaction. Among them, as a catalyst for metathesis reaction, bis(tricyclohexylphosphine)benzylideneruthenium dichloride, 1,3-bis(2,4,6-trimethylphenyl)-2-(imidazolidinylidene)(dichlorophenylmethylene)(tricyclo It is preferred to use a Grubbs catalyst such as xylphosphine)ruthenium. Furthermore, as the coolefin, olefins having 2 to 16 carbon atoms such as ethylene, isobutane, and 1-hexane can be used. Further, as a hydrogenation catalyst for hydrogenation after the metathesis reaction, a known homogeneous hydrogenation catalyst such as a Wilkinson catalyst ((PPh 3 ) 3 RhCl) can be used.
＜＜重合体の性状＞＞
［重量平均分子量］
　重合体の重量平均分子量は、２，０００以上であることが好ましく、５，０００以上であることがより好ましく、１０，０００以上であることが更に好ましく、１５，０００以上であることが一層好ましく、２０，０００以上であることがより一層好ましく、２５，０００以上であることが特に好ましく、２００，０００以下であることが好ましく、１７０，０００以下であることがより好ましく、１５０，０００以下であることが更に好ましく、１００，０００以下であることが一層好ましく、５０，０００以下であることがより一層好ましく、２８，０００以下であることが特に好ましい。重量平均分子量が上記下限以上であれば、ＣＮＴ分散液中のＣＮＴの分散性を更に向上させることができる。一方、重合体の重量平均分子量が上記上限以下であれば、重合体のＣＮＴに対する吸着量が増大し、ＣＮＴ分散液中のＣＮＴの分散性を更に向上させると共に、ＣＮＴ分散液の粘度安定性を向上させることができる。また、重合体の重量平均分子量が上記上限以下であれば、ＣＮＴ分散液を用いて調製したスラリー組成物から形成される電極合材層の接着性を高めることができる。さらに、重合体の重量平均分子量が上記上限以下であれば、当該電極合材層を備える二次電池のサイクル特性及び高温保存特性を向上させることができる。
　重合体の平均分子量は、例えば、重合時に配合する分子量調整剤の配合量を調節することにより、制御することができる。 <<Properties of polymer>>
[Weight average molecular weight]
The weight average molecular weight of the polymer is preferably 2,000 or more, more preferably 5,000 or more, even more preferably 10,000 or more, and even more preferably 15,000 or more. , is even more preferably 20,000 or more, particularly preferably 25,000 or more, preferably 200,000 or less, more preferably 170,000 or less, and 150,000 or less. It is more preferably 100,000 or less, even more preferably 50,000 or less, and particularly preferably 28,000 or less. If the weight average molecular weight is at least the above lower limit, the dispersibility of CNTs in the CNT dispersion can be further improved. On the other hand, if the weight average molecular weight of the polymer is below the above upper limit, the adsorption amount of the polymer to CNTs will increase, further improving the dispersibility of CNTs in the CNT dispersion, and improving the viscosity stability of the CNT dispersion. can be improved. Moreover, if the weight average molecular weight of a polymer is below the said upper limit, the adhesiveness of the electrode composite material layer formed from the slurry composition prepared using CNT dispersion liquid can be improved. Furthermore, if the weight average molecular weight of the polymer is below the above upper limit, the cycle characteristics and high temperature storage characteristics of the secondary battery including the electrode composite material layer can be improved.
The average molecular weight of the polymer can be controlled, for example, by adjusting the amount of a molecular weight regulator added during polymerization.
［ヘイズ］
　重合体の８質量％水溶液のヘイズは、ｐＨ８．０以上において、７０％以下であることが好ましく、６８％以下であることがより好ましく、６４％以下であることが更に好ましく、５８％以下であることが一層好ましく、５０％以下であることがより一層好ましく、４０％以下であることが更に一層好ましく、３０％以下であることが特に好ましい。重合体の上記所定の水溶液のヘイズが上記上限以下であれば、重合体のＣＮＴに対する吸着量が増大するので、ＣＮＴ分散液中のＣＮＴの分散性を更に向上させると共に、ＣＮＴ分散液の粘度安定性を向上させることができる。また、重合体の上記所定の水溶液のヘイズが上記上限以下であれば、ＣＮＴ分散液を用いて調製したスラリー組成物から形成される電極合材層の接着性を高めることができる。さらに、重合体の上記所定の水溶液のヘイズが上記上限以下であれば、当該電極合材層中において、重合体が水分を捕捉することで水分による充放電機能の阻害が生じ難くなるためと推察されるが、二次電池のサイクル特性及び高温保存特性を向上させることができる。
　また、重合体の８質量％水溶液のヘイズの下限は、特に限定されないが、例えば、０％以上であってもよいし、５％以上であってもよい。
　なお、重合体の上記所定の水溶液のヘイズは、重合体の組成（各種の繰り返し単位の含有割合）、及び重量平均分子量、並びに重合体の製造方法の条件などによって制御することができる。 [Haze]
The haze of an 8% by mass aqueous solution of the polymer is preferably 70% or less, more preferably 68% or less, even more preferably 64% or less, and even more preferably 58% or less at pH 8.0 or higher. It is more preferably at most 50%, even more preferably at most 40%, particularly preferably at most 30%. If the haze of the above-mentioned predetermined aqueous solution of the polymer is below the above-mentioned upper limit, the adsorption amount of the polymer to CNTs will increase, which will further improve the dispersibility of CNTs in the CNT dispersion and stabilize the viscosity of the CNT dispersion. can improve sex. Moreover, if the haze of the above-mentioned predetermined aqueous solution of the polymer is below the above-mentioned upper limit, the adhesiveness of the electrode composite material layer formed from the slurry composition prepared using the CNT dispersion liquid can be improved. Furthermore, if the haze of the above-mentioned predetermined aqueous solution of the polymer is below the above-mentioned upper limit, it is presumed that the polymer captures water in the electrode composite layer, making it difficult for the charge/discharge function to be inhibited by water. However, the cycle characteristics and high temperature storage characteristics of the secondary battery can be improved.
Further, the lower limit of the haze of the 8% by mass aqueous solution of the polymer is not particularly limited, but may be, for example, 0% or more, or 5% or more.
Note that the haze of the above-mentioned predetermined aqueous solution of the polymer can be controlled by the composition of the polymer (the content ratio of various repeating units), the weight average molecular weight, and the conditions of the method for producing the polymer.
［ヨウ素価］
　重合体のヨウ素価は、５ｍｇ／１００ｍｇ以上であることが好ましく、７ｍｇ／１００ｍｇ以上であることがより好ましく、１０ｍｇ／１００ｍｇ以上であることが更に好ましく、１００ｍｇ／１００ｍｇ以下であることが好ましく、８０ｍｇ／１００ｍｇ以下であることがより好ましく、７０ｍｇ／１００ｍｇ以下であることが更に好ましい。重合体のヨウ素価が上記下限以上であれば、ＣＮＴ分散液中のＣＮＴの分散性を更に向上させることができる。一方、重合体のヨウ素価が上記上限以下であれば、重合体のＣＮＴに対する吸着量が増大し、ＣＮＴ分散液中のＣＮＴの分散性を更に向上させると共に、ＣＮＴ分散液の粘度安定性を向上させることができる。また、重合体のヨウ素価が上記上限以下であれば、ＣＮＴ分散液を用いて調製したスラリー組成物から形成される電極合材層の接着性を高めることができる。さらに、重合体のヨウ素価が上記上限以下であれば、当該電極合材層を備える二次電池のサイクル特性及び高温保存特性を向上させることができる。
　また、重合体のヨウ素価は、５０ｍｇ／１００ｍｇ以下であってもよいし、３５ｍｇ／１００ｍｇ以下であってもよいし、２５ｍｇ／１００ｍｇ以下であってもよいし、１５ｍｇ／１００ｍｇ以下であってもよい。
　なお、重合体のヨウ素価は、例えば、重合体を水素化する際に用いる水素化触媒の量などに基づいて、制御することができる。 [Iodine value]
The iodine value of the polymer is preferably 5 mg/100 mg or more, more preferably 7 mg/100 mg or more, even more preferably 10 mg/100 mg or more, preferably 100 mg/100 mg or less, and 80 mg/100 mg or more. /100mg or less is more preferable, and even more preferably 70mg/100mg or less. If the iodine value of the polymer is at least the above lower limit, the dispersibility of CNTs in the CNT dispersion can be further improved. On the other hand, if the iodine value of the polymer is below the above upper limit, the adsorption amount of the polymer to CNTs will increase, further improving the dispersibility of CNTs in the CNT dispersion, and improving the viscosity stability of the CNT dispersion. can be done. Moreover, if the iodine value of the polymer is below the above upper limit, the adhesiveness of the electrode composite material layer formed from the slurry composition prepared using the CNT dispersion can be improved. Furthermore, if the iodine value of the polymer is below the above upper limit, the cycle characteristics and high temperature storage characteristics of the secondary battery including the electrode composite layer can be improved.
Further, the iodine value of the polymer may be 50 mg/100 mg or less, 35 mg/100 mg or less, 25 mg/100 mg or less, or 15 mg/100 mg or less. good.
Note that the iodine value of the polymer can be controlled based on, for example, the amount of hydrogenation catalyst used when hydrogenating the polymer.
＜＜重合体の含有量＞＞
　ＣＮＴ分散液中の重合体の含有量は、ＣＮＴ１００質量部に対して、１０質量部以上であることが好ましく、１５質量部以上であることがより好ましく、２０質量部以上であることが更に好ましく、１００質量部以下であることが好ましく、５０質量部以下であることがより好ましく、３０質量部以下であることが更に好ましい。ＣＮＴ分散液中の重合体の含有量が上記所定の範囲内であれば、ＣＮＴ分散液中のＣＮＴの分散性を更に向上させることができる。 <<Polymer content>>
The content of the polymer in the CNT dispersion is preferably 10 parts by mass or more, more preferably 15 parts by mass or more, and even more preferably 20 parts by mass or more, based on 100 parts by mass of CNTs. , is preferably 100 parts by mass or less, more preferably 50 parts by mass or less, and even more preferably 30 parts by mass or less. If the content of the polymer in the CNT dispersion liquid is within the above-mentioned predetermined range, the dispersibility of CNTs in the CNT dispersion liquid can be further improved.
＜分散媒＞
　ＣＮＴ分散液に含まれる分散媒としては、特に限定されることはなく、水及び有機溶媒のいずれも用いることができる。有機溶媒としては、例えば、Ｎ－メチルピロリドン（ＮＭＰ）、Ｎ，Ｎ－ジメチルホルムアミド、アセトンなどが挙げられる。有機溶媒としては、ＣＮＴ分散液中のＣＮＴの分散性を更に向上させる観点から、Ｎ－メチルピロリドン（ＮＭＰ）を用いることが好ましい。なお、分散媒としては、１種を単独で用いてもよいし、２種以上を任意の比率で混合して用いてもよい。 <Dispersion medium>
The dispersion medium contained in the CNT dispersion is not particularly limited, and both water and organic solvents can be used. Examples of the organic solvent include N-methylpyrrolidone (NMP), N,N-dimethylformamide, and acetone. As the organic solvent, N-methylpyrrolidone (NMP) is preferably used from the viewpoint of further improving the dispersibility of CNTs in the CNT dispersion. In addition, as a dispersion medium, one type may be used individually, and two or more types may be mixed and used in arbitrary ratios.
　なお、ＣＮＴ分散液中の分散媒の含有量は、ＣＮＴ分散液の固形分濃度が、例えば１質量％以上、好ましくは２質量％以上、より好ましくは３質量％以上、また、例えば３０質量％以下、好ましくは２５質量％以下、より好ましくは２０質量％以下となるように調整することができる。 The content of the dispersion medium in the CNT dispersion liquid is such that the solid content concentration of the CNT dispersion liquid is, for example, 1% by mass or more, preferably 2% by mass or more, more preferably 3% by mass or more, and, for example, 30% by mass. The content can be adjusted to preferably 25% by mass or less, more preferably 20% by mass or less.
＜その他の成分＞
　本発明のＣＮＴ分散液は、上記成分の他に、補強材、レベリング剤、粘度調整剤、電解液添加剤等の成分を含有していてもよい。これらは、電池反応に影響を及ぼさないものであれば特に限られず、公知のもの、例えば国際公開第２０１２／１１５０９６号に記載のものを使用することができる。また、これらの成分は、１種類を単独で用いてもよく、２種類以上を任意の比率で組み合わせて用いてもよい。 <Other ingredients>
The CNT dispersion liquid of the present invention may contain components such as a reinforcing material, a leveling agent, a viscosity modifier, and an electrolyte additive in addition to the above components. These are not particularly limited as long as they do not affect the battery reaction, and known ones, such as those described in International Publication No. 2012/115096, can be used. Furthermore, these components may be used alone or in combination of two or more in any ratio.
　また、本発明のＣＮＴ分散液は、ＣＮＴ以外の導電材を更に含んでいてもよい。ＣＮＴ以外のその他の導電材としては、カーボンブラック（例えば、アセチレンブラック、ケッチェンブラック（登録商標）、ファーネスブラックなど）、グラファイト、カーボンナノチューブ以外の炭素繊維、カーボンフレーク等の導電性炭素材料；各種金属のファイバー、箔などを用いることができる。これらは一種単独で、又は、２種以上を組み合わせて用いることができる。
　しかしながら、ＣＮＴ分散液中のＣＮＴの分散性及びＣＮＴ分散液の粘度安定性を十分に高く確保する観点から、本発明のＣＮＴ分散液は、ＣＮＴ以外の導電材を含まないことが好ましい。 Moreover, the CNT dispersion liquid of the present invention may further contain a conductive material other than CNT. Examples of conductive materials other than CNT include carbon black (e.g., acetylene black, Ketjen Black (registered trademark), furnace black, etc.), graphite, carbon fibers other than carbon nanotubes, carbon flakes, and other conductive carbon materials; Metal fibers, foil, etc. can be used. These can be used alone or in combination of two or more.
However, from the viewpoint of ensuring sufficiently high dispersibility of CNTs in the CNT dispersion and viscosity stability of the CNT dispersion, the CNT dispersion of the present invention preferably does not contain any conductive material other than CNTs.
＜ＣＮＴ分散液の製造方法＞
　本発明のＣＮＴ分散液は、分散媒中に、カーボンナノチューブを分散させると共に、上述した重合体及び任意のその他の成分を溶解又は分散させることにより調製することができる。より具体的には、本発明のＣＮＴ分散液は、カーボンナノチューブと、上述した重合体と、任意のその他の成分とを、分散処理を行いながら混合することにより調製することができる。なお、ＣＮＴ分散液の調製においては、上記分散処理を行いながらの混合の前に、必要に応じて、予備混合を行ってもよい。また、ＣＮＴ分散液の調製に用いる重合体は、分散媒中に溶解又は分散してなる溶液又は分散液の状態であってもよい。 <Method for producing CNT dispersion>
The CNT dispersion of the present invention can be prepared by dispersing carbon nanotubes and dissolving or dispersing the above-mentioned polymer and any other components in a dispersion medium. More specifically, the CNT dispersion of the present invention can be prepared by mixing carbon nanotubes, the above-mentioned polymer, and any other components while performing a dispersion treatment. In addition, in the preparation of the CNT dispersion liquid, preliminary mixing may be performed as necessary before mixing while performing the above-mentioned dispersion treatment. Furthermore, the polymer used for preparing the CNT dispersion may be in the form of a solution or dispersion obtained by dissolving or dispersing it in a dispersion medium.
　そして、分散処理を行いながらの混合は、例えば、ボールミル、サンドミル、ビーズミル、顔料分散機、らい潰機、超音波分散機、ホモジナイザー、プラネタリーミキサー、薄膜旋回型高速ミキサーなどの分散機を用いて行うことができる。中でも、得られるＣＮＴ分散液中のＣＮＴの分散性を更に向上させる観点から、薄膜旋回型高速ミキサーを用いて分散処理を行うことが好ましい。 Mixing while performing dispersion treatment can be carried out using a dispersion machine such as a ball mill, sand mill, bead mill, pigment dispersion machine, crusher, ultrasonic dispersion machine, homogenizer, planetary mixer, thin film swirl type high-speed mixer, etc. It can be carried out. Among these, from the viewpoint of further improving the dispersibility of CNTs in the obtained CNT dispersion, it is preferable to perform the dispersion treatment using a thin film swirling type high-speed mixer.
　薄膜旋回型高速ミキサーとしては、プライミクス社製「フィルミックス（登録商標）」を用いることができる。なお、「フィルミックス（登録商標）」の型番としては、ＣＮＴ分散液の製造スケールに応じて、「３０－Ｌ型」、「４０－Ｌ型」、「５６－Ｌ型」、「５６型」、「８０型」、「１２５型」、「１５６型」、「２５２型」等を選択して用いることができる。 As the thin film swirling type high-speed mixer, "Filmix (registered trademark)" manufactured by Primix Co., Ltd. can be used. In addition, the model number of "Filmix (registered trademark)" is "30-L type", "40-L type", "56-L type", "56 type" depending on the manufacturing scale of CNT dispersion liquid. , "80 type", "125 type", "156 type", "252 type", etc. can be selected and used.
　上記プライミクス社製「フィルミックス（登録商標）」等の薄膜旋回型高速ミキサーを用いて分散処理を行う場合の分散条件は、本発明の所望の効果が得られる範囲内で適宜調整可能である。
　例えば、薄膜旋回型高速ミキサーのタービンの周速は５ｍ／ｓ以上であることが好ましく、１０ｍ／ｓ以上であることがより好ましく、１５ｍ／ｓ以上であることが更に好ましく、５０ｍ／ｓ以下であることが好ましく、４０ｍ／ｓ以下であることがより好ましく、３０ｍ／ｓ以下であることが更に好ましい。薄膜旋回型高速ミキサーのタービンの周速が上記下限以上であれば、得られるＣＮＴ分散液中のＣＮＴの分散性を一層向上させることができる。一方、薄膜旋回型高速ミキサーのタービンの周速が上記上限以下であれば、過剰な負荷によるＣＮＴの切断を抑制して、ＣＮＴ分散液を含むスラリー組成物を用いて形成した電極合材層を備える二次電池のサイクル特性を十分に高く確保することができる。 The dispersion conditions when carrying out the dispersion treatment using a thin film swirl type high-speed mixer such as "Filmix (registered trademark)" manufactured by Primix Co., Ltd. can be adjusted as appropriate within the range where the desired effect of the present invention can be obtained.
For example, the circumferential speed of the turbine of a thin film swirling type high-speed mixer is preferably 5 m/s or more, more preferably 10 m/s or more, even more preferably 15 m/s or more, and even more preferably 50 m/s or less. The speed is preferably at most 40 m/s, more preferably at most 30 m/s, even more preferably at most 30 m/s. If the circumferential speed of the turbine of the thin film swirl type high-speed mixer is equal to or higher than the above lower limit, the dispersibility of CNTs in the resulting CNT dispersion can be further improved. On the other hand, if the circumferential speed of the turbine of the thin film swirl type high-speed mixer is below the above upper limit, cutting of CNTs due to excessive load can be suppressed, and the electrode mixture layer formed using a slurry composition containing a CNT dispersion can be It is possible to ensure sufficiently high cycle characteristics of the secondary battery provided.
　また、分散処理の処理時間は、３０秒以上であることが好ましく、６０秒以上であることがより好ましく、８０秒以上であることが更に好ましく、１００秒以上であることが一層好ましく、３００秒以下であることが好ましく、２５０秒以下であることがより好ましく、２００秒以下であることが更に好ましく、１５０秒以下であることが一層好ましい。分散処理の処理時間が上記下限以上であれば、得られるＣＮＴ分散液中のＣＮＴの分散性を一層向上させることができる。一方、分散処理の処理時間が上記上限以下であれば、過剰な負荷によるＣＮＴの切断を抑制して、ＣＮＴ分散液を含むスラリー組成物を用いて形成した電極合材層を備える二次電池のサイクル特性を十分に高く確保することができる。 Further, the processing time of the distributed processing is preferably 30 seconds or more, more preferably 60 seconds or more, even more preferably 80 seconds or more, even more preferably 100 seconds or more, and 300 seconds or more. It is preferably at most 250 seconds, more preferably at most 200 seconds, even more preferably at most 150 seconds. If the treatment time of the dispersion treatment is at least the above-mentioned lower limit, the dispersibility of CNTs in the resulting CNT dispersion can be further improved. On the other hand, if the treatment time of the dispersion treatment is less than the above upper limit, cutting of CNTs due to excessive load can be suppressed, and a secondary battery equipped with an electrode composite layer formed using a slurry composition containing a CNT dispersion liquid can be manufactured. Sufficiently high cycle characteristics can be ensured.
＜ＣＮＴ分散液中のＣＮＴの体積平均粒子径Ｄ５０＞
　本発明のＣＮＴ分散液中においては、ＣＮＴが微粒子の状態で良好かつ安定的に分散されている。
　ＣＮＴ分散液中のＣＮＴの体積平均粒子径Ｄ５０は、０．１μｍ以上であることが好ましく、１５．０μｍ以下であることが好ましく、１２．０μｍ以下であることがより好ましく、１０．０μｍ以下であることが更に好ましく、７．５μｍ以下であることが一層好ましい。ＣＮＴ分散液中のＣＮＴの体積平均粒子径Ｄ５０が上記所定の範囲内であれば、ＣＮＴ分散液中のＣＮＴの分散性を更に向上させることができる。 <Volume average particle diameter D50 of CNT in CNT dispersion>
In the CNT dispersion of the present invention, CNTs are well and stably dispersed in the form of fine particles.
The volume average particle diameter D50 of the CNTs in the CNT dispersion is preferably 0.1 μm or more, preferably 15.0 μm or less, more preferably 12.0 μm or less, and 10.0 μm or less. It is more preferable that the particle size is 7.5 μm or less. If the volume average particle diameter D50 of CNTs in the CNT dispersion liquid is within the above-described predetermined range, the dispersibility of CNTs in the CNT dispersion liquid can be further improved.
（非水系二次電池電極用スラリー組成物）
　本発明の非水系二次電池電極用スラリー組成物は、電極活物質と、上述した本発明の導電材分散液を含む。即ち、本発明の非水系二次電池電極用スラリー組成物は、電極活物質と、導電材としてのＣＮＴと、重合体と、溶媒とを含み、加えて、任意のその他の成分を更に含有する。
　なお、本発明の非水系二次電池電極用スラリー組成物に含まれるＣＮＴ、及び重合体は、本発明のＣＮＴ分散液に由来するものであり、それらの好適な存在比は、本発明のＣＮＴ分散液と同様である。 (Slurry composition for non-aqueous secondary battery electrodes)
The slurry composition for a non-aqueous secondary battery electrode of the present invention contains an electrode active material and the above-described conductive material dispersion of the present invention. That is, the slurry composition for a non-aqueous secondary battery electrode of the present invention contains an electrode active material, CNTs as a conductive material, a polymer, and a solvent, and further contains any other components. .
The CNTs and polymer contained in the slurry composition for a non-aqueous secondary battery electrode of the present invention are derived from the CNT dispersion of the present invention, and their preferred abundance ratio is that of the CNTs of the present invention. It is the same as the dispersion liquid.
＜電極活物質＞
　スラリー組成物に配合する電極活物質（正極活物質、負極活物質）としては、特に限定されることなく、既知の電極活物質を用いることができる。本発明のスラリー組成物は、電極活物質として、正極活物質を含んでいてもよいし、負極活物質を含んでいてもよい。即ち、本発明のスラリー組成物は、正極用スラリー組成物であってもよいし、負極用スラリー組成物であってもよい。
　なお、以下では、一例として非水系二次電池がリチウムイオン二次電池である場合の正極活物質について説明するが、本発明は下記の一例に限定されるものではない。 <Electrode active material>
The electrode active material (positive electrode active material, negative electrode active material) to be added to the slurry composition is not particularly limited, and known electrode active materials can be used. The slurry composition of the present invention may contain a positive electrode active material or a negative electrode active material as an electrode active material. That is, the slurry composition of the present invention may be a positive electrode slurry composition or a negative electrode slurry composition.
In addition, although the positive electrode active material in case a non-aqueous secondary battery is a lithium ion secondary battery is demonstrated below as an example, this invention is not limited to the following example.
　例えば、リチウムイオン二次電池用の正極活物質としては、特に限定されることなく、リチウム含有コバルト酸化物（ＬｉＣｏＯ２）、マンガン酸リチウム（ＬｉＭｎ２Ｏ４）、リチウム含有ニッケル酸化物（ＬｉＮｉＯ２）、Ｃｏ－Ｎｉ－Ｍｎのリチウム含有複合酸化物、Ｎｉ－Ｍｎ－Ａｌのリチウム含有複合酸化物、Ｎｉ－Ｃｏ－Ａｌのリチウム含有複合酸化物、オリビン型リン酸鉄リチウム（ＬｉＦｅＰＯ４）、オリビン型リン酸マンガンリチウム（ＬｉＭｎＰＯ４）、Ｌｉ１＋ｘＭｎ２－ｘＯ４（０＜Ｘ＜２）で表されるリチウム過剰のスピネル化合物、Ｌｉ［Ｎｉ０．１７Ｌｉ０．２Ｃｏ０．０７Ｍｎ０．５６］Ｏ２、ＬｉＮｉ０．５Ｍｎ１．５Ｏ４等の既知の正極活物質が挙げられる。なお、Ｃｏ－Ｎｉ－Ｍｎのリチウム含有複合酸化物としては、Ｌｉ（Ｎｉ０．６Ｃｏ０．２Ｍｎ０．２）Ｏ２、Ｌｉ（Ｎｉ０．５Ｃｏ０．２Ｍｎ０．３）Ｏ２、Ｌｉ（Ｎｉ１／３Ｃｏ１／３Ｍｎ１／３）Ｏ２などが挙げられる。
　上述した中でも、二次電池の電池容量などを向上させる観点からは、正極活物質としては、リチウム含有コバルト酸化物（ＬｉＣｏＯ２）、リチウム含有ニッケル酸化物（ＬｉＮｉＯ２）、Ｃｏ－Ｎｉ－Ｍｎのリチウム含有複合酸化物、Ｌｉ［Ｎｉ０．１７Ｌｉ０．２Ｃｏ０．０７Ｍｎ０．５６］Ｏ２又はＬｉＮｉ０．５Ｍｎ１．５Ｏ４を用いることが好ましく、Ｃｏ－Ｎｉ－Ｍｎのリチウム含有複合酸化物を用いることがより好ましい。 For example, positive electrode active materials for lithium ion secondary batteries include, but are not limited to, lithium-containing cobalt oxide (LiCoO 2 ), lithium manganate (LiMn 2 O 4 ), and lithium-containing nickel oxide (LiNiO 2 ) . ), Co-Ni-Mn lithium-containing composite oxide, Ni-Mn-Al lithium-containing composite oxide, Ni-Co-Al lithium-containing composite oxide, olivine-type lithium iron phosphate (LiFePO 4 ), olivine type lithium manganese phosphate (LiMnPO 4 ), lithium-excess spinel compound represented by Li 1+x Mn 2-x O 4 (0<X<2), Li[Ni 0.17 Li 0.2 Co 0.07 Mn 0.56 ]O 2 , LiNi 0.5 Mn 1.5 O 4 , and other known positive electrode active materials. Note that the lithium-containing composite oxide of Co-Ni-Mn includes Li(Ni 0.6 Co 0.2 Mn 0.2 )O 2 and Li(Ni 0.5 Co 0.2 Mn 0.3 )O. 2 , Li(Ni 1/3 Co 1/3 Mn 1/3 ) O 2 and the like.
Among the above, from the viewpoint of improving the battery capacity of secondary batteries, lithium-containing cobalt oxide (LiCoO 2 ), lithium-containing nickel oxide (LiNiO 2 ), and Co-Ni-Mn are used as positive electrode active materials. It is preferable to use a lithium-containing composite oxide, Li[Ni 0.17 Li 0.2 Co 0.07 Mn 0.56 ]O 2 or LiNi 0.5 Mn 1.5 O 4 , and Co-Ni-Mn It is more preferable to use a lithium-containing composite oxide.
　なお、電極活物質の配合量や粒径は、特に限定されることなく、従来使用されている正極活物質と同様とすることができる。 Note that the blending amount and particle size of the electrode active material are not particularly limited, and can be the same as those of conventionally used positive electrode active materials.
＜ＣＮＴ分散液＞
　ＣＮＴ分散液としては、上述した本発明のＣＮＴ分散液を用いる。 <CNT dispersion>
As the CNT dispersion, the above-mentioned CNT dispersion of the present invention is used.
＜含有比率＞
　スラリー組成物中のＣＮＴの含有量は、電極活物質１００質量部に対して、０．０１質量部以上２０質量部以下であることが好ましい。スラリー組成物中のＣＮＴの含有量が上記下限以上であれば、電極活物質同士の電気的接触を促進することができる。また、スラリー組成物中のＣＮＴの含有量が上記上限以下であれば、スラリー組成物の塗工性を高めることができる。
　また、スラリー組成物中の重合体の好適な含有量は、＜＜重合体の含有量＞＞の項目にて上述したＣＮＴに対する重合体の好適な含有量の範囲、及び本段落の冒頭で説明した電極活物質に対するＣＮＴの含有量より導出される好適な範囲内であり得る。 <Content ratio>
The content of CNT in the slurry composition is preferably 0.01 parts by mass or more and 20 parts by mass or less based on 100 parts by mass of the electrode active material. If the content of CNT in the slurry composition is equal to or higher than the above lower limit, electrical contact between electrode active materials can be promoted. Moreover, if the content of CNT in the slurry composition is below the above-mentioned upper limit, the coatability of the slurry composition can be improved.
In addition, the suitable content of the polymer in the slurry composition is explained in the range of the suitable content of the polymer for CNT mentioned above in the item <<Polymer content>> and at the beginning of this paragraph. It may be within a suitable range derived from the CNT content for the electrode active material.
＜その他の成分＞
　スラリー組成物に配合し得るその他の成分としては、特に限定することなく、本発明のバインダー組成物に配合し得るその他の成分と同様のものが挙げられる。なお、その他の成分は、１種類を単独で用いてもよく、２種類以上を任意の比率で組み合わせて用いてもよい。また、本発明のスラリー組成物がリチウムイオン二次電池正極用スラリー組成物である場合には、上述した重合体に加えて、結着剤として、ポリフッ化ビニリデン（ＰＶｄＦ）等のフッ素含有重合体を併用することが好ましい。スラリー組成物が上述した重合体以外に、１種又は複数種の結着剤を含有する場合には、かかる１種又は複数種の結着剤の全含有量を１００質量部として、上述した重合体の量は５質量部以上５０質量部以下であり得る。スラリー組成物中における上述した重合体の含有割合が上記下限値以上であれば、得られる二次電池の高温保存特性を高めることができる。また、上述した重合体の含有割合が上記上限値以下であれば、電極合材層の接着性を高めることができる。 <Other ingredients>
Other components that can be blended into the slurry composition are not particularly limited, and include the same components as those that can be blended into the binder composition of the present invention. In addition, one type of other components may be used alone, or two or more types may be used in combination in any ratio. Further, when the slurry composition of the present invention is a slurry composition for a positive electrode of a lithium ion secondary battery, in addition to the above-mentioned polymer, a fluorine-containing polymer such as polyvinylidene fluoride (PVdF) may be used as a binder. It is preferable to use them together. When the slurry composition contains one or more types of binders in addition to the above-mentioned polymers, the total content of the one or more types of binders is 100 parts by mass, and the above-mentioned polymers are The amount of coalescence can be 5 parts by weight or more and 50 parts by weight or less. When the content of the above-mentioned polymer in the slurry composition is equal to or higher than the lower limit, the high-temperature storage characteristics of the obtained secondary battery can be improved. Moreover, if the content rate of the polymer mentioned above is below the said upper limit, the adhesiveness of an electrode composite material layer can be improved.
＜スラリー組成物の製造方法＞
　上述したスラリー組成物は、上記各成分を水及び有機溶媒などの溶媒中に溶解又は分散させることにより調製することができる。例えば、上述したＣＮＴ分散液に対して、電極活物質、溶媒及び任意成分などを添加して、既知の方法により混合する工程を行って、本発明のスラリー組成物を調製することが好ましい。なお、有機溶媒としては、＜分散媒＞の項目にて上述したＣＮＴ分散液に用い得る有機溶媒を用いることができる。 <Method for manufacturing slurry composition>
The slurry composition described above can be prepared by dissolving or dispersing each of the components described above in a solvent such as water and an organic solvent. For example, it is preferable to prepare the slurry composition of the present invention by adding an electrode active material, a solvent, optional components, etc. to the above-mentioned CNT dispersion and mixing them using a known method. Note that as the organic solvent, an organic solvent that can be used for the CNT dispersion liquid described above in the section of <Dispersion medium> can be used.
（非水系二次電池用電極）
　本発明の非水系二次電池用電極は、本発明の非水系二次電池電極用スラリー組成物を用いて形成した電極合材層を備える。より具体的には、本発明の電極は、集電体上に本発明のスラリー組成物を用いて形成した電極合材層を備える。即ち、電極合材層には、少なくとも、電極活物質と、重合体と、導電材としてのカーボンナノチューブとが含まれている。なお、電極合材層中に含まれている各成分は、上記スラリー組成物中に含まれていたものであり、それら各成分の好適な存在比は、スラリー組成物中の各成分の好適な存在比と同じである。
　そして、本発明の非水系二次電池用電極を用いることで、例えば、サイクル特性及び高温保存特性などの電池特性に優れる二次電池を形成することができる。 (Electrode for non-aqueous secondary batteries)
The electrode for a non-aqueous secondary battery of the present invention includes an electrode mixture layer formed using the slurry composition for a non-aqueous secondary battery electrode of the present invention. More specifically, the electrode of the present invention includes an electrode mixture layer formed using the slurry composition of the present invention on a current collector. That is, the electrode composite material layer contains at least an electrode active material, a polymer, and carbon nanotubes as a conductive material. In addition, each component contained in the electrode mixture layer was contained in the above slurry composition, and the preferable abundance ratio of each component is determined by the preferable abundance ratio of each component in the slurry composition. It is the same as the abundance ratio.
By using the electrode for non-aqueous secondary batteries of the present invention, it is possible to form a secondary battery that has excellent battery characteristics such as cycle characteristics and high-temperature storage characteristics.
＜非水系二次電池用電極の製造方法＞
　なお、本発明の非水系二次電池用電極は、例えば、上述したスラリー組成物を集電体上に塗布する工程（塗布工程）と、集電体上に塗布されたスラリー組成物を乾燥して集電体上に電極合材層を形成する工程（乾燥工程）とを経て製造される。
　なお、本発明の非水系二次電池用電極は、上述したスラリー組成物を乾燥造粒して複合粒子を調製し、当該複合粒子を用いて集電体上に電極合材層を形成する方法によっても製造することができる。 <Method for manufacturing electrodes for non-aqueous secondary batteries>
Note that the electrode for a non-aqueous secondary battery of the present invention includes, for example, a step of applying the above-mentioned slurry composition onto a current collector (coating step) and drying the slurry composition applied onto the current collector. and a step (drying step) of forming an electrode mixture layer on the current collector.
The electrode for a non-aqueous secondary battery of the present invention can be prepared by drying and granulating the slurry composition described above to prepare composite particles, and using the composite particles to form an electrode mixture layer on a current collector. It can also be manufactured by
［塗布工程］
　上記スラリー組成物を集電体上に塗布する方法としては、特に限定されず公知の方法を用いることができる。具体的には、塗布方法としては、ドクターブレード法、ディップ法、リバースロール法、ダイレクトロール法、グラビア法、エクストルージョン法、ハケ塗り法などを用いることができる。この際、非水系二次電池電極用スラリー組成物を集電体の片面だけに塗布してもよいし、両面に塗布してもよい。塗布後乾燥前の集電体上のスラリー膜の厚みは、乾燥して得られる電極合材層の厚みに応じて適宜に設定しうる。 [Coating process]
The method for applying the slurry composition onto the current collector is not particularly limited, and any known method can be used. Specifically, as a coating method, a doctor blade method, a dip method, a reverse roll method, a direct roll method, a gravure method, an extrusion method, a brush coating method, etc. can be used. At this time, the slurry composition for a non-aqueous secondary battery electrode may be applied to only one side of the current collector, or may be applied to both sides. The thickness of the slurry film on the current collector after coating and before drying can be appropriately set depending on the thickness of the electrode mixture layer obtained by drying.
　ここで、スラリー組成物を塗布する集電体としては、電気導電性を有し、かつ、電気化学的に耐久性のある材料が用いられる。具体的には、集電体としては、例えば、鉄、銅、アルミニウム、ニッケル、ステンレス鋼、チタン、タンタル、金、白金などからなる集電体を用い得る。中でも、正極に用いる集電体としては、アルミニウム箔が特に好ましい。なお、前記の材料は、１種類を単独で用いてもよく、２種類以上を任意の比率で組み合わせて用いてもよい。 Here, as the current collector to which the slurry composition is applied, a material that has electrical conductivity and is electrochemically durable is used. Specifically, as the current collector, for example, a current collector made of iron, copper, aluminum, nickel, stainless steel, titanium, tantalum, gold, platinum, etc. can be used. Among these, aluminum foil is particularly preferred as the current collector used for the positive electrode. Note that the above-mentioned materials may be used alone or in combination of two or more in any ratio.
［乾燥工程］
　集電体上のスラリー組成物を乾燥する方法としては、特に限定されず公知の方法を用いることができ、例えば温風、熱風、低湿風による乾燥、真空乾燥、赤外線や電子線などの照射による乾燥法が挙げられる。このように集電体上のスラリー組成物を乾燥することで、集電体上に電極合材層を形成し、集電体と電極合材層とを備える非水系二次電池用電極を得ることができる。 [Drying process]
The method of drying the slurry composition on the current collector is not particularly limited and any known method can be used, such as drying with hot air, hot air, low humidity air, vacuum drying, irradiation with infrared rays, electron beams, etc. An example is a drying method. By drying the slurry composition on the current collector in this way, an electrode mixture layer is formed on the current collector, and an electrode for a non-aqueous secondary battery including the current collector and the electrode mixture layer is obtained. be able to.
　また、本発明の非水系二次電池用電極の製造方法では、乾燥工程の後、金型プレス又はロールプレスなどを用い、電極合材層に加圧処理を施してもよい。加圧処理により、電極合材層と集電体との密着性を向上させることができる。
　さらに、電極合材層が硬化性の重合体を含む場合は、電極合材層の形成後に前記重合体を硬化させることが好ましい。 Further, in the method for manufacturing an electrode for a non-aqueous secondary battery of the present invention, after the drying step, the electrode mixture layer may be subjected to pressure treatment using a mold press, a roll press, or the like. The pressure treatment can improve the adhesion between the electrode composite material layer and the current collector.
Furthermore, when the electrode composite material layer contains a curable polymer, it is preferable to harden the polymer after forming the electrode composite material layer.
（非水系二次電池）
　本発明の非水系二次電池は、上述した本発明の非水系二次電池用電極を備える。具体的には、本発明の非水系二次電池は、正極と、負極と、電解液と、セパレータとを備え、正極及び負極の少なくとも一方として本発明の非水系二次電池用電極を用いたものである。そして、本発明の非水系二次電池は、本発明の非水系二次電池用電極を備えているので、例えば、サイクル特性及び高温保存特性などの電池特性に優れる。本発明の非水系二次電池において、正極が本発明の電極であり、負極が本発明の電極以外の電極であってもよいし、正極が本発明の電極以外の電極であり、負極が本発明の電極であってもよいし、正極及び負極の双方が本発明の電極であってもよい。
　なお、以下では、一例として非水系二次電池がリチウムイオン二次電池である場合について説明するが、本発明は下記の一例に限定されるものではない。 (Non-aqueous secondary battery)
The non-aqueous secondary battery of the present invention includes the above-described electrode for a non-aqueous secondary battery of the present invention. Specifically, the non-aqueous secondary battery of the present invention includes a positive electrode, a negative electrode, an electrolyte, and a separator, and the non-aqueous secondary battery electrode of the present invention is used as at least one of the positive electrode and the negative electrode. It is something. Since the non-aqueous secondary battery of the present invention includes the electrode for non-aqueous secondary batteries of the present invention, it has excellent battery characteristics such as cycle characteristics and high-temperature storage characteristics. In the nonaqueous secondary battery of the present invention, the positive electrode may be the electrode of the present invention, and the negative electrode may be an electrode other than the electrode of the present invention, or the positive electrode may be an electrode other than the electrode of the present invention, and the negative electrode may be the electrode of the present invention. The electrode of the invention may be used, or both the positive electrode and the negative electrode may be the electrode of the invention.
In addition, although the case where a non-aqueous secondary battery is a lithium ion secondary battery is demonstrated below as an example, this invention is not limited to the following example.
＜本発明の電極以外の電極＞
　本発明の電極に該当しない電極としては、特に限定されず既知の電極を用いることができる。 <Electrodes other than the electrodes of the present invention>
Electrodes that do not correspond to the electrodes of the present invention are not particularly limited, and known electrodes can be used.
＜電解液＞
　電解液としては、通常、有機溶媒に支持電解質を溶解した有機電解液が用いられる。支持電解質としては、例えば、リチウム塩が用いられる。リチウム塩としては、例えば、ＬｉＰＦ６、ＬｉＡｓＦ６、ＬｉＢＦ４、ＬｉＳｂＦ６、ＬｉＡｌＣｌ４、ＬｉＣｌＯ４、ＣＦ３ＳＯ３Ｌｉ、Ｃ４Ｆ９ＳＯ３Ｌｉ、ＣＦ３ＣＯＯＬｉ、（ＣＦ３ＣＯ）２ＮＬｉ、（ＣＦ３ＳＯ２）２ＮＬｉ、（Ｃ２Ｆ５ＳＯ２）ＮＬｉなどが挙げられる。なかでも、溶媒に溶けやすく高い解離度を示すので、ＬｉＰＦ６、ＬｉＣｌＯ４、ＣＦ３ＳＯ３Ｌｉが好ましく、ＬｉＰＦ６が特に好ましい。なお、電解質は１種類を単独で用いてもよく、２種類以上を任意の比率で組み合わせて用いてもよい。通常は、解離度の高い支持電解質を用いるほどリチウムイオン伝導度が高くなる傾向があるので、支持電解質の種類によりリチウムイオン伝導度を調節することができる。 <Electrolyte>
As the electrolytic solution, an organic electrolytic solution in which a supporting electrolyte is dissolved in an organic solvent is usually used. As the supporting electrolyte, for example, lithium salt is used. Examples of lithium salts include LiPF 6 , LiAsF 6 , LiBF 4 , LiSbF 6 , LiAlCl 4 , LiClO 4 , CF 3 SO 3 Li, C 4 F 9 SO 3 Li, CF 3 COOLi, (CF 3 CO) 2 NLi. , (CF 3 SO 2 ) 2 NLi, (C 2 F 5 SO 2 ) NLi, and the like. Among these, LiPF 6 , LiClO 4 , and CF 3 SO 3 Li are preferred, and LiPF 6 is particularly preferred since they are easily soluble in solvents and exhibit a high degree of dissociation. Note that one type of electrolyte may be used alone, or two or more types may be used in combination in any ratio. Usually, the lithium ion conductivity tends to increase as a supporting electrolyte with a higher degree of dissociation is used, so the lithium ion conductivity can be adjusted depending on the type of supporting electrolyte.
　電解液に使用する有機溶媒としては、支持電解質を溶解できるものであれば特に限定されないが、例えば、ジメチルカーボネート（ＤＭＣ）、エチレンカーボネート（ＥＣ）、ジエチルカーボネート（ＤＥＣ）、プロピレンカーボネート（ＰＣ）、ブチレンカーボネート（ＢＣ）、メチルエチルカーボネート（ＥＭＣ）等のカーボネート類；γ－ブチロラクトン、ギ酸メチル等のエステル類；１，２－ジメトキシエタン、テトラヒドロフラン等のエーテル類；スルホラン、ジメチルスルホキシド等の含硫黄化合物類；などが好適に用いられる。またこれらの溶媒の混合液を用いてもよい。なお、電解液中の電解質の濃度は適宜調整することができる。 The organic solvent used in the electrolyte is not particularly limited as long as it can dissolve the supporting electrolyte, but examples include dimethyl carbonate (DMC), ethylene carbonate (EC), diethyl carbonate (DEC), propylene carbonate (PC), Carbonates such as butylene carbonate (BC) and methyl ethyl carbonate (EMC); Esters such as γ-butyrolactone and methyl formate; Ethers such as 1,2-dimethoxyethane and tetrahydrofuran; Sulfur-containing compounds such as sulfolane and dimethyl sulfoxide etc. are preferably used. Alternatively, a mixture of these solvents may be used. Note that the concentration of the electrolyte in the electrolytic solution can be adjusted as appropriate.
＜セパレータ＞
　セパレータとしては、特に限定されることなく、例えば特開２０１２－２０４３０３号公報に記載のものを用いることができる。これらの中でも、セパレータ全体の膜厚を薄くすることができ、これにより、二次電池内の電極活物質の比率を高くして体積あたりの容量を高くすることができるという点より、ポリオレフィン系（ポリエチレン、ポリプロピレン、ポリブテン）の樹脂からなる微多孔膜が好ましい。また、セパレータとしては、当該微多孔膜の表面に、接着性を有する層（即ち、接着層）が形成されてなる接着層付きセパレータや耐熱性を有する層（即ち、耐熱層）が形成されてなる耐熱層付きセパレータを用いてもよい。 <Separator>
The separator is not particularly limited, and for example, those described in JP-A No. 2012-204303 can be used. Among these, polyolefin-based ( A microporous membrane made of a resin such as polyethylene, polypropylene, or polybutene is preferred. In addition, the separator may be a separator with an adhesive layer formed by forming an adhesive layer (i.e., adhesive layer) on the surface of the microporous membrane, or a separator with an adhesive layer formed on the surface of the microporous membrane, or a separator with an adhesive layer formed on the surface of the microporous membrane. A separator with a heat-resistant layer may also be used.
＜二次電池の製造方法＞
　本発明の二次電池は、例えば、正極と、負極とを、セパレータを介して重ね合わせ、これを必要に応じて電池形状に応じて巻く、折るなどして電池容器に入れ、電池容器に電解液を注入して封口することにより製造することができる。二次電池の内部の圧力上昇、過充放電等の発生を防止するために、必要に応じて、ヒューズ、ＰＴＣ素子等の過電流防止素子、エキスパンドメタル、リード板などを設けてもよい。二次電池の形状は、例えば、コイン型、ボタン型、シート型、円筒型、角形、扁平型など、何れであってもよい。 <Method for manufacturing secondary batteries>
In the secondary battery of the present invention, for example, a positive electrode and a negative electrode are stacked on top of each other with a separator interposed therebetween, and this is rolled or folded according to the shape of the battery as necessary, and placed in a battery container, and the battery is electrolyzed in the battery container. It can be manufactured by injecting a liquid and sealing it. In order to prevent an increase in pressure inside the secondary battery, overcharging and discharging, etc., a fuse, an overcurrent prevention element such as a PTC element, an expanded metal, a lead plate, etc. may be provided as necessary. The shape of the secondary battery may be, for example, a coin shape, a button shape, a sheet shape, a cylindrical shape, a square shape, a flat shape, or the like.
　以下、本発明について実施例に基づき具体的に説明するが、本発明はこれら実施例に限定されるものではない。なお、以下の説明において、量を表す「％」及び「部」は、特に断らない限り、質量基準である。
　また、複数種類の単量体を共重合して製造される重合体において、ある単量体を重合して形成される単量体単位の前記重合体における割合は、別に断らない限り、通常は、その重合体の重合に用いる全単量体に占める当該ある単量体の比率(仕込み比)と一致する。また、重合体が、共役ジエン単量体単位を含む重合物を水素添加（水添）してなる水添重合体である場合に、水添重合体における、未水添の共役ジエン単量体単位と、水素添加された共役ジエン単量体単位としてのアルキレン構造単位との合計含有割合は、重合物の重合に用いた全単量体に占める、共役ジエン単量体の比率（仕込み比）と一致する。
　実施例及び比較例において、下記の方法で、各種の測定及び評価を行った。 EXAMPLES Hereinafter, the present invention will be specifically explained based on Examples, but the present invention is not limited to these Examples. In the following description, "%" and "part" representing amounts are based on mass unless otherwise specified.
In addition, in a polymer produced by copolymerizing multiple types of monomers, the proportion of monomer units formed by polymerizing a certain monomer in the polymer is usually , corresponds to the ratio of the certain monomer to the total monomers used in the polymerization of the polymer (feeding ratio). In addition, when the polymer is a hydrogenated polymer obtained by hydrogenating (hydrogenating) a polymer containing conjugated diene monomer units, unhydrogenated conjugated diene monomer in the hydrogenated polymer The total content ratio of the unit and the alkylene structural unit as a hydrogenated conjugated diene monomer unit is the ratio of the conjugated diene monomer to the total monomers used for polymerization of the polymer (preparation ratio) matches.
In Examples and Comparative Examples, various measurements and evaluations were performed using the following methods.
＜重合体の重量平均分子量＞
　重合体の重量平均分子量（Ｍｗ）を、濃度１０ｍＭのＬｉＢｒ－ＤＭＦ溶液を使用し、下記の測定条件でゲル浸透クロマトグラフィー（ＧＰＣ）より測定した。
・分離カラム：Ｓｈｏｄｅｘ  ＫＤ－８０６Ｍ（昭和電工株式会社製）
・検出器：示差屈折計検出器  ＲＩＤ－１０Ａ（株式会社島津製作所製）
・溶離液の流速：０．３ｍＬ／分
・カラム温度：４０℃
・標準ポリマー：ＴＳＫ  標準ポリスチレン（東ソー株式会社製） <Weight average molecular weight of polymer>
The weight average molecular weight (Mw) of the polymer was measured by gel permeation chromatography (GPC) using a LiBr-DMF solution with a concentration of 10 mM under the following measurement conditions.
・Separation column: Shodex KD-806M (manufactured by Showa Denko Co., Ltd.)
・Detector: Differential refractometer detector RID-10A (manufactured by Shimadzu Corporation)
・Flow rate of eluent: 0.3 mL/min ・Column temperature: 40°C
・Standard polymer: TSK standard polystyrene (manufactured by Tosoh Corporation)
＜重合体の８質量％水溶液のヘイズ＞
　実施例及び比較例で得られた重合体の水分散液に対して、水を更に添加して、重合体の濃度が８質量％である水溶液を得た。なお、得られた重合体８質量％水溶液のｐＨを測定したところｐＨ９．５であることを確認した。
　ヘイズメーター（製品名「ＮＤＨ７０００ＳＰ」、日本電色工業社製、ＪＩＳ Ｋ ７１３６：２０００に準拠した装置）を用い、２５℃条件下で、液体測定用ガラスセルに水を入れて標準校正をしたのち、ガラスセルに、上記で得られた重合体８質量％水溶液（ｐＨ９．５）を入れて、ヘイズを測定した。 <Haze of 8% by mass aqueous solution of polymer>
Water was further added to the aqueous dispersions of polymers obtained in Examples and Comparative Examples to obtain aqueous solutions having a polymer concentration of 8% by mass. In addition, when the pH of the obtained 8% by mass aqueous solution of the polymer was measured, it was confirmed that the pH was 9.5.
Using a haze meter (product name "NDH7000SP", manufactured by Nippon Denshoku Kogyo Co., Ltd., a device compliant with JIS K 7136:2000), at 25°C, after performing standard calibration by filling a glass cell for liquid measurement with water. The 8% by mass aqueous solution (pH 9.5) of the polymer obtained above was placed in a glass cell, and the haze was measured.
＜重合体のヨウ素価＞
　実施例、比較例で調製した重合体の水分散液１００ｇを、メタノール１Ｌで凝固させた後、温度６０℃で１２時間真空乾燥した。そして、得られた乾燥重合体のヨウ素価を、ＪＩＳ Ｋ６２３５（２００６）に従って測定した。 <Iodine value of polymer>
100 g of the aqueous dispersion of the polymer prepared in Examples and Comparative Examples was coagulated with 1 L of methanol, and then vacuum-dried at a temperature of 60° C. for 12 hours. Then, the iodine value of the obtained dry polymer was measured according to JIS K6235 (2006).
＜比吸光度の変化率ΔＥ＞
＜＜ＣＮＴ分散液の比吸光度Ｅ１の測定＞＞
　実施例、比較例で調製したＣＮＴ分散液に対して、重合体の０．８質量％ＮＭＰ溶液を添加して固形分濃度を０．０５質量％に調整した後、ボルテックスミキサー（ジェニー２）を用いて周速８００ｒｐｍで撹拌して、測定用ＣＮＴ分散液を得た。得られた測定用ＣＮＴ分散液の質量対容量比濃度を０．０６ｍｇ／ｍＬとみなした。
　ここで、上記「重合体の０．８質量％ＮＭＰ溶液」としては、ＣＮＴ分散液を調製した実施例又は比較例と同じ実施例又は比較例で調製したバインダー組成物（重合体の８質量％水溶液）をＮＭＰで希釈し、重合体の濃度を０．８質量％に調整することで得られたものを用いた。なお、上記「重合体の０．８質量％ＮＭＰ溶液」としては、ＣＮＴ分散液に対して遠心処理及びメンブレンフィルターによる濾過等の必要な処理をして、当該ＣＮＴ分散液からＣＮＴを除去して得られた液を、必要に応じて濃縮又はＮＭＰによる希釈を行い、固形分濃度を０．８質量％に調整して得られたものを用いることもできる。
　そして、紫外可視分光法（Ｕｖ－Ｖｉｓ）により、測定用ＣＮＴ分散液の吸光度を測定し、みなし濃度０．０６ｍｇ／ｍＬにおける吸光度Ａ（０．０６）とした。なお、吸光度の測定は下記の条件で行った。
　　　紫外線・可視分光光度計：Ｊａｓｃｏ社製「Ｖ－７５０」
　　　Ｕｖ－Ｖｉｓ測定ソフトウェア：Ｊａｓｃｏ スペクトルマネージャー
　　　サンプル容器：石英セル（光路長１０ｍｍ）
　次いで、上記で調製した測定用ＣＮＴ分散液（固形分濃度：０．０５質量％）に対して上記重合体の０．８質量％ＮＭＰ溶液を添加して容量基準で２倍に希釈して、希釈後の測定用ＣＮＴ分散液を得た。希釈後の測定用ＣＮＴ分散液の質量対容量比濃度を０．０３ｍｇ／ｍＬとみなした。そして、上記同様の条件で、希釈後の測定用ＣＮＴ分散液の吸光度を測定し、みなし濃度０．０３ｍｇ／ｍＬにおける吸光度Ａ（０．０３）とした。
　また、上記と同様にして、希釈に用いた上記重合体の０．８質量％ＮＭＰ溶液の吸光度を測定し、みなし濃度０ｍｇ／ｍＬにおける吸光度Ａ（０）とした。
　そして、縦軸を吸光度とし、横軸をみなし濃度（ｍｇ／ｍＬ）とするグラフ上で、上記で得られたＡ（０）、Ａ（０．０３）、及びＡ（０．０６）の測定結果をプロットした。ランベルト・ベールの法則に従って、プロット結果から検量線を作成し、得られた検量線の傾きを測定用ＣＮＴ分散液の比吸光度Ｅ１とした。
＜＜上澄み液の比吸光度Ｅ２の測定＞＞
　遠心分離機を用いて、測定用ＣＮＴ分散液を４０００ｒｐｍで１分間遠心処理して、上澄み液を得た。得られた上澄み液の質量対容量比濃度を０．０６ｍｇ／ｍＬとみなした。そして、上記同様の条件で、上澄み液の吸光度を測定し、みなし濃度０．０６ｍｇ／ｍＬにおける吸光度Ａ´（０．０６）とした。
　次いで、上記で得られた上澄み液に対して上記重合体の０．８質量％ＮＭＰ溶液を添加して容量基準で２倍に希釈し、希釈後の上澄み液を得た。希釈後の上澄み液の質量対容量比濃度を０．０３ｍｇ／ｍＬとみなした。そして、上記同様の条件で、希釈後の上澄み液の吸光度を測定し、みなし濃度０．０３ｍｇ／ｍＬにおける吸光度Ａ´（０．０３）とした。
　また、上記と同様にして、希釈に用いた上記重合体の０．８質量％ＮＭＰ溶液の吸光度を測定し、みなし濃度０ｍｇ／ｍＬにおける吸光度Ａ´（０）とした。
　そして、縦軸を吸光度とし、横軸をみなし濃度（ｍｇ／ｍＬ）とするグラフ上で、上記で得られたＡ´（０）、Ａ´（０．０３）、及びＡ´（０．０６）の測定結果をプロットした。ランベルト・ベールの法則に従って、プロット結果から検量線を作成し、得られた検量線の傾きを上澄み液の比吸光度Ｅ２とした。
＜＜遠心処理前後の比吸光度の変化率ΔＥの算出＞＞
　そして、得られたＥ１及びＥ２から、式：ΔＥ＝１００×（Ｅ１－Ｅ２）／Ｅ１により遠心処理前後での比吸光度の変化率ΔＥを算出した。 <Change rate ΔE of specific absorbance>
<<Measurement of specific absorbance E1 of CNT dispersion>>
After adding a 0.8% by mass NMP solution of the polymer to the CNT dispersions prepared in Examples and Comparative Examples to adjust the solid content concentration to 0.05% by mass, a vortex mixer (Jenny 2) was added. A CNT dispersion for measurement was obtained by stirring at a circumferential speed of 800 rpm. The mass-to-volume ratio concentration of the obtained CNT dispersion for measurement was considered to be 0.06 mg/mL.
Here, the above-mentioned "0.8 mass% NMP solution of polymer" is a binder composition (8 mass% of polymer Aqueous solution) was diluted with NMP and the polymer concentration was adjusted to 0.8% by mass. The above-mentioned "0.8 mass% NMP solution of polymer" is obtained by subjecting the CNT dispersion to necessary treatments such as centrifugation and filtration with a membrane filter to remove CNTs from the CNT dispersion. The obtained liquid may be concentrated or diluted with NMP as necessary to adjust the solid content concentration to 0.8% by mass, and the obtained liquid may also be used.
Then, the absorbance of the CNT dispersion for measurement was measured by ultraviolet-visible spectroscopy (Uv-Vis), and was defined as absorbance A (0.06) at a deemed concentration of 0.06 mg/mL. Note that the absorbance was measured under the following conditions.
Ultraviolet/visible spectrophotometer: “V-750” manufactured by Jasco
Uv-Vis measurement software: Jasco Spectrum Manager Sample container: Quartz cell (light path length 10 mm)
Next, a 0.8% by mass NMP solution of the above polymer was added to the CNT dispersion for measurement prepared above (solid content concentration: 0.05% by mass) and diluted to 2 times by volume. A CNT dispersion liquid for measurement after dilution was obtained. The mass-to-volume ratio concentration of the CNT dispersion for measurement after dilution was considered to be 0.03 mg/mL. Then, the absorbance of the CNT dispersion for measurement after dilution was measured under the same conditions as above, and the absorbance was defined as absorbance A (0.03) at a deemed concentration of 0.03 mg/mL.
Further, in the same manner as above, the absorbance of a 0.8% by mass NMP solution of the polymer used for dilution was measured, and the absorbance was defined as absorbance A(0) at a deemed concentration of 0 mg/mL.
Then, measure A(0), A(0.03), and A(0.06) obtained above on a graph where the vertical axis is the absorbance and the horizontal axis is the deemed concentration (mg/mL). The results were plotted. A calibration curve was created from the plotting results according to Beer-Lambert's law, and the slope of the obtained calibration curve was defined as the specific absorbance E1 of the CNT dispersion for measurement.
<<Measurement of specific absorbance E2 of supernatant liquid>>
Using a centrifuge, the CNT dispersion for measurement was centrifuged at 4000 rpm for 1 minute to obtain a supernatant. The mass-to-volume ratio concentration of the obtained supernatant was considered to be 0.06 mg/mL. Then, the absorbance of the supernatant liquid was measured under the same conditions as above, and the absorbance was defined as absorbance A' (0.06) at a deemed concentration of 0.06 mg/mL.
Next, a 0.8% by mass NMP solution of the above polymer was added to the supernatant obtained above to dilute it twice on a volume basis to obtain a diluted supernatant. The mass-to-volume concentration of the supernatant after dilution was assumed to be 0.03 mg/mL. Then, the absorbance of the diluted supernatant liquid was measured under the same conditions as above, and the absorbance was defined as absorbance A' (0.03) at a deemed concentration of 0.03 mg/mL.
Further, in the same manner as above, the absorbance of a 0.8% by mass NMP solution of the polymer used for dilution was measured, and the absorbance was defined as absorbance A'(0) at a deemed concentration of 0 mg/mL.
Then, on a graph where the vertical axis is the absorbance and the horizontal axis is the deemed concentration (mg/mL), A'(0), A'(0.03), and A'(0.06) obtained above are plotted. ) measurement results are plotted. A calibration curve was created from the plotting results according to the Lambert-Beer law, and the slope of the obtained calibration curve was defined as the specific absorbance E2 of the supernatant liquid.
<<Calculation of rate of change ΔE in specific absorbance before and after centrifugation treatment>>
Then, from the obtained E1 and E2, the rate of change in specific absorbance ΔE before and after centrifugation was calculated using the formula: ΔE=100×(E1−E2)/E1.
＜ＣＮＴ分散液中のＣＮＴの体積平均粒子径Ｄ５０＞
　実施例、比較例で調製したＣＮＴ分散液を用いて、レーザー回折・散乱式粒度分布測定装置（日機社装、「マイクロトラックＭＴ３２００ＩＩ」）による乾式の積分粒子径分布によって、測定時の分散用空気の圧力を０．０２ＭＰａとして、ＣＮＴ分散液中のＣＮＴの体積基準の平均粒子径Ｄ５０を測定した。 <Volume average particle diameter D50 of CNT in CNT dispersion>
Using the CNT dispersions prepared in Examples and Comparative Examples, the dispersion during measurement was determined by dry integrated particle size distribution using a laser diffraction/scattering particle size distribution analyzer (Nikkishaso, "Microtrack MT3200II"). The volume-based average particle diameter D50 of the CNTs in the CNT dispersion was measured at an air pressure of 0.02 MPa.
＜ＣＮＴ分散液におけるＣＮＴの分散性＞
　実施例、比較例で調製したＣＮＴ分散液の粘度について、レオメーター（Ａｎｔｏｎ Ｐａａｒ社製ＭＣＲ３０２）にて、温度２５℃、せん断速度２．５ｓ-1の条件下で粘度を測定し、以下の基準にて評価した。なお、同一固形分濃度においては、ＣＮＴ分散液の粘度が低いほど、当該ＣＮＴ分散液におけるＣＮＴの分散性が優れていることを意味する。
　　Ａ：粘度が５０００ｍＰａ・ｓ未満
　　Ｂ：粘度が５０００ｍＰａ・ｓ以上１００００ｍＰａ・ｓ未満
　　Ｃ：粘度が１００００ｍＰａ・ｓ以上１０００００ｍＰａ・ｓ未満
　　Ｄ：粘度が１０００００ｍＰａ・ｓ以上 <Dispersibility of CNT in CNT dispersion>
The viscosity of the CNT dispersions prepared in Examples and Comparative Examples was measured using a rheometer (MCR302 manufactured by Anton Paar) under the conditions of a temperature of 25°C and a shear rate of 2.5 s -1 , and the viscosity was measured according to the following standards. It was evaluated. Note that, at the same solid content concentration, the lower the viscosity of the CNT dispersion, the better the dispersibility of CNT in the CNT dispersion.
A: Viscosity is less than 5000 mPa・s B: Viscosity is 5000 mPa・s or more and less than 10000 mPa・s C: Viscosity is 10000 mPa・s or more and less than 100000 mPa・s D: Viscosity is 100000 mPa・s or more
＜重合体のＣＮＴに対する吸着量＞
　実施例、比較例で調製したバインダー組成物としての重合体ＮＭＰ溶液４．０部（固形分相当量）と、導電材としてのカーボンナノチューブ（比表面積：２８０ｍ２／ｇ）４．０部と、適量のＮＭＰとをディスパーに添加し、その後撹拌（３０００ｒｐｍ、６０分）し、固形分濃度が１０質量％の吸着量測定用ＣＮＴペーストを調製した。そして吸着量測定用ＣＮＴペーストに、固形分濃度が１質量％となるようにＮＭＰを添加し、希釈液を得た。
　この希釈液を、遠心分離機を用いて、回転速度１００００ｒｐｍで１０分間遠心分離した。得られた沈殿物を真空乾燥機にて１５０℃で３時間乾燥させ、乾燥物を得た。この時、乾燥による質量変化がなくなったことを確認した。
　この乾燥物を、熱天秤を用いて、窒素雰囲気下、昇温速度１０℃／分で５００℃まで加熱処理を行い、熱天秤により測定される加熱処理前の乾燥物の質量Ｗ１（ｇ）、加熱処理後に得られる残留物の質量Ｗ２（ｇ）から、以下の式により、重合体の導電材（ＣＮＴ）に対する吸着量を算出し、下記の基準に従って評価した。
　式：吸着量（ｍｇ／ｇ）＝｛（Ｗ１－Ｗ２）×１０００｝／Ｗ２
　　Ａ：１１０ｍｇ／ｇ以上１０００ｍｇ／ｇ以下
　　Ｂ：８０ｍｇ／ｇ以上１１０ｍｇ／ｇ未満
　　Ｃ：６０ｍｇ／ｇ以上８０ｍｇ／ｇ未満
　　Ｄ：４０ｍｇ／ｇ以上６０ｍｇ／ｇ未満 <Adsorption amount of polymer to CNT>
4.0 parts of polymer NMP solution (solid content equivalent) as a binder composition prepared in Examples and Comparative Examples, and 4.0 parts of carbon nanotubes (specific surface area: 280 m 2 /g) as a conductive material, An appropriate amount of NMP was added to a disper and then stirred (3000 rpm, 60 minutes) to prepare a CNT paste for adsorption measurement with a solid content concentration of 10% by mass. Then, NMP was added to the CNT paste for adsorption amount measurement so that the solid content concentration was 1% by mass to obtain a diluted solution.
This diluted solution was centrifuged using a centrifuge at a rotation speed of 10,000 rpm for 10 minutes. The obtained precipitate was dried in a vacuum dryer at 150° C. for 3 hours to obtain a dried product. At this time, it was confirmed that there was no change in mass due to drying.
This dried material is heat-treated to 500°C at a temperature increase rate of 10°C/min in a nitrogen atmosphere using a thermobalance, and the mass W1 (g) of the dried material before heat treatment is measured by the thermobalance. From the mass W2 (g) of the residue obtained after the heat treatment, the adsorption amount of the polymer to the conductive material (CNT) was calculated using the following formula, and evaluated according to the following criteria.
Formula: Adsorption amount (mg/g) = {(W1-W2)×1000}/W2
A: 110 mg/g or more and 1000 mg/g or less B: 80 mg/g or more and less than 110 mg/g C: 60 mg/g or more and less than 80 mg/g D: 40 mg/g or more and less than 60 mg/g
＜ＣＮＴ分散液の粘度安定性＞
　実施例、比較例で調製したＣＮＴ分散液の粘度変化率を求めるために、次の操作を行った。即ち、レオメーター（Ａｎｔｏｎ Ｐａａｒ社製「ＭＣＲ３０２」）を用いて、温度２５℃、せん断速度２．５ｓ-1の条件下で、上記ＣＮＴ分散液について、それぞれ調製直後の粘度を測定し、得られた粘度をη０とした。次に、ＣＮＴ分散液を密封状態とし、２５℃で１週間（１６８時間）放置した。その後、１週間放置後のＣＮＴ分散液の粘度について、１週間放置する前と同じ条件下で測定し、得られた粘度をη１とした。η０及びη１の値から粘度変化率Δη＝（η１／η０）×１００［％］を算出した。粘度変化率が１００％に近いほど、ＣＮＴ分散液の粘度安定性が高いことを意味し、ＣＮＴ分散液の保管後における導電材（カーボンナノチューブ）の分散性が高くなる。そのため、正極合材層内部に良好な導電パスを形成させることができるので、電池抵抗値を低減することができる。
　　Ａ：粘度維持率Δηが９０％以上１１０％以下
　　Ｂ：粘度維持率Δηが８０％以上９０％未満
　　Ｃ：粘度維持率Δηが７０％以上８０％未満
　　Ｄ：粘度維持率Δηが７０％未満、又は１１０％超 <Viscosity stability of CNT dispersion>
In order to determine the viscosity change rate of the CNT dispersions prepared in Examples and Comparative Examples, the following operation was performed. That is, using a rheometer ("MCR302" manufactured by Anton Paar), the viscosity of each of the above CNT dispersions immediately after preparation was measured under the conditions of a temperature of 25 ° C. and a shear rate of 2.5 s -1 . The viscosity obtained was defined as η0. Next, the CNT dispersion liquid was sealed and left at 25° C. for one week (168 hours). Thereafter, the viscosity of the CNT dispersion after being left for one week was measured under the same conditions as before being left for one week, and the obtained viscosity was defined as η1. The viscosity change rate Δη=(η1/η0)×100[%] was calculated from the values of η0 and η1. The closer the viscosity change rate is to 100%, the higher the viscosity stability of the CNT dispersion, and the higher the dispersibility of the conductive material (carbon nanotubes) after storage of the CNT dispersion. Therefore, a good electrically conductive path can be formed inside the positive electrode composite material layer, so that the battery resistance value can be reduced.
A: Viscosity maintenance rate Δη is 90% or more and 110% or less B: Viscosity maintenance rate Δη is 80% or more and less than 90% C: Viscosity maintenance rate Δη is 70% or more and less than 80% D: Viscosity maintenance rate Δη is less than 70%, or more than 110%
＜サイクル特性＞
　実施例、比較例で作製したリチウムイオン二次電池を、電解液注液後、温度２５℃で５時間静置した。次に、温度２５℃、０．２Ｃの定電流法にて、セル電圧３．６５Ｖまで充電し、その後、温度６０℃で１２時間エージング処理を行った。そして、温度２５℃、０．２Ｃの定電流法にて、セル電圧３．００Ｖまで放電した。その後、０．２Ｃの定電流法にて、ＣＣ－ＣＶ充電（上限セル電圧４．２０Ｖ）を行い、０．２Ｃの定電流法にて３．００ＶまでＣＣ放電した。この０．２Ｃにおける充放電を３回繰り返し実施した。
　その後、温度４５℃の環境下、セル電圧４．２０－３．００Ｖ、１．０Ｃの充放電レートにて充放電の操作を１００サイクル行った。その際、第１回目のサイクルの放電容量をＸ１、第１００回目のサイクルの放電容量をＸ２と定義した。放電容量Ｘ１及び放電容量Ｘ２を用いて、ΔＣ＝（Ｘ２／Ｘ１）×１００（％）で示される容量維持率を求め、以下の基準により評価した。この容量維持率ΔＣの値が大きいほど、リチウムイオン二次電池がサイクル特性に優れていることを示す。
　　Ａ：容量維持率が９５％以上
　　Ｂ：容量維持率が９０％以上９５％未満
　　Ｃ：容量維持率が８５％以上９０％未満
　　Ｄ：容量維持率が８５％未満 <Cycle characteristics>
The lithium ion secondary batteries produced in Examples and Comparative Examples were left standing at a temperature of 25° C. for 5 hours after injecting the electrolyte. Next, the battery was charged to a cell voltage of 3.65 V by a constant current method at a temperature of 25° C. and 0.2 C, and then an aging treatment was performed at a temperature of 60° C. for 12 hours. Then, the cell was discharged to a cell voltage of 3.00 V using a constant current method at a temperature of 25° C. and 0.2 C. Thereafter, CC-CV charging (upper limit cell voltage 4.20V) was performed using a constant current method at 0.2C, and CC discharge was performed to 3.00V using a constant current method at 0.2C. This charging and discharging at 0.2C was repeated three times.
Thereafter, 100 cycles of charging and discharging were performed at a cell voltage of 4.20-3.00V and a charge/discharge rate of 1.0C in an environment at a temperature of 45°C. At that time, the discharge capacity of the first cycle was defined as X1, and the discharge capacity of the 100th cycle was defined as X2. Using the discharge capacity X1 and the discharge capacity X2, the capacity retention rate represented by ΔC=(X2/X1)×100(%) was determined and evaluated according to the following criteria. The larger the value of this capacity retention rate ΔC, the better the cycle characteristics of the lithium ion secondary battery are.
A: Capacity retention rate is 95% or more B: Capacity retention rate is 90% or more and less than 95% C: Capacity retention rate is 85% or more and less than 90% D: Capacity retention rate is less than 85%
＜高温保存特性＞
　実施例、比較例で作製したリチウムイオン二次電池を、電解液注液後、温度２５℃で、５時間静置した。次に、温度２５℃、０．２Ｃの定電流法にて、セル電圧３．６５Ｖまで充電し、その後、温度６０℃で１２時間エージング処理を行った。そして、温度２５℃、０．２Ｃの定電流法にて、セル電圧３．００Ｖまで放電した。その後、０．２Ｃの定電流にて、ＣＣ－ＣＶ充電（上限セル電圧４．２０Ｖ）を行い、０．２Ｃの定電流にてセル電圧３．００ＶまでＣＣ放電を行った。この０．２Ｃにおける充放電を３回繰り返し実施した。この０．２Ｃにおける３回目の放電容量を初期容量ＣＸとした。その後、０．２Ｃの定電流にて、ＣＣ－ＣＶ充電（上限セル電圧４．２０Ｖ)を行った。次いで、処理室内を６０℃窒素雰囲気としたイナー卜オーブン中に、リチウムイオン二次電池を４週間保管した。その後、０．２Ｃの定電流法にて、セル電圧３．００Ｖまで放電し、このときの放電容量をＣＹとした。(ＣＹ／ＣＸ）×１００（％）で示される高温容量維持率を求め、下記の基準で評価した。高温容量維持率が大きいほど、高温保存におけるリチウムイオン二次電池の劣化が少ない（即ち、高温保存特性に優れる）ことを示す。
　　Ａ：高温容量維持率が９０％以上
　　Ｂ：高温容量維持率が８５％以上９０％未満
　　Ｃ：高温容量維持率が８０％以上８５％未満
　　Ｄ：高温容量維持率が８０％未満 <High temperature storage characteristics>
The lithium ion secondary batteries produced in Examples and Comparative Examples were left standing at a temperature of 25° C. for 5 hours after injecting the electrolyte. Next, the battery was charged to a cell voltage of 3.65 V by a constant current method at a temperature of 25° C. and 0.2 C, and then an aging treatment was performed at a temperature of 60° C. for 12 hours. Then, the cell was discharged to a cell voltage of 3.00 V using a constant current method at a temperature of 25° C. and 0.2 C. Thereafter, CC-CV charging (upper limit cell voltage 4.20V) was performed at a constant current of 0.2C, and CC discharge was performed at a constant current of 0.2C to a cell voltage of 3.00V. This charging and discharging at 0.2C was repeated three times. The third discharge capacity at 0.2C was defined as the initial capacity CX. Thereafter, CC-CV charging (upper limit cell voltage 4.20V) was performed at a constant current of 0.2C. Next, the lithium ion secondary battery was stored for 4 weeks in an inner oven with a nitrogen atmosphere at 60° C. inside the processing chamber. Thereafter, the battery was discharged to a cell voltage of 3.00 V using a constant current method at 0.2 C, and the discharge capacity at this time was defined as CY. The high temperature capacity retention rate expressed as (CY/CX) x 100 (%) was determined and evaluated based on the following criteria. The larger the high-temperature capacity retention rate, the less deterioration of the lithium ion secondary battery during high-temperature storage (that is, the better the high-temperature storage characteristics).
A: High temperature capacity retention rate is 90% or more B: High temperature capacity retention rate is 85% or more and less than 90% C: High temperature capacity retention rate is 80% or more and less than 85% D: High temperature capacity retention rate is less than 80%
（実施例１）
＜重合体（バインダー組成物）の調製＞
　反応器に、イオン交換水２００部、濃度１０％のドデシルベンゼンスルホン酸ナトリウム水溶液２５部、ニトリル基含有単量体単位としてのアクリロニトリル３０部、親水性基含有単量体単位としてのメタクリル酸１０部、及び連鎖移動剤としてのｔ－ドデシルメルカプタン２．５０部を順に仕込んだ。次いで、内部の気体を窒素で３回置換した後、共役ジエン単量体としての１，３－ブタジエン６０部を仕込んだ。そして、反応器を１０℃に保ち、重合開始剤としてのクメンハイドロパーオキサイド０．０３部、還元剤、及びキレート剤適量を仕込み、攪拌しながら重合反応を継続し、重合転化率が８０％になった時点で、重合停止剤としての濃度１０％のハイドロキノン水溶液０．１部を加えて重合反応を停止した。次いで、水温８０℃で残留単量体を除去し、重合体の前駆体の水分散液を得た。
　得られた重合体の前駆体の水分散液に含有される固形分重量に対するパラジウム含有量が３，０００ｐｐｍになるように、オートクレーブ中に、水分散液とパラジウム触媒（１％酢酸パラジウムアセトン溶液と等重量のイオン交換水を混合した溶液）を添加して、水素圧３ＭＰａ、温度５５℃で３時間水素添加反応を行い、目的の重合体（水素化ニトリルゴム）の水分散液を得た。
　その後、内容物を常温に戻し、系内を窒素雰囲気とした後、エバポレータを用いて、固形分濃度が４０％となるまで濃縮した。
　次に、濃縮後の重合体の水分散液に対して２．５％ＫＯＨ水溶液を添加し、ｐＨ９．５に調整した。ｐＨ調整後の重合体の水分散液を用いて、ヘイズ及びヨウ素価を測定した。
　ｐＨ調整後の重合体の水分散液１００部に、Ｎ－メチルピロリドン２００部を加え、減圧下に水、残留単量体をすべて蒸発させたのち、Ｎ－メチルピロリドンを蒸発させて、バインダー組成物として、重合体の８質量％ＮＭＰ溶液を得た。得られたバインダー組成物を用いて、重合体の重量平均分子量及び重合体のＣＮＴに対する吸着量を測定及び評価した。 (Example 1)
<Preparation of polymer (binder composition)>
In a reactor, 200 parts of ion-exchanged water, 25 parts of a 10% concentration sodium dodecylbenzenesulfonate aqueous solution, 30 parts of acrylonitrile as a nitrile group-containing monomer unit, and 10 parts of methacrylic acid as a hydrophilic group-containing monomer unit were placed in a reactor. , and 2.50 parts of t-dodecylmercaptan as a chain transfer agent were charged in this order. Next, after replacing the internal gas with nitrogen three times, 60 parts of 1,3-butadiene as a conjugated diene monomer was charged. Then, while maintaining the reactor at 10°C, 0.03 part of cumene hydroperoxide as a polymerization initiator, a reducing agent, and an appropriate amount of a chelating agent were charged, and the polymerization reaction was continued with stirring until the polymerization conversion rate was 80%. At that point, 0.1 part of a 10% aqueous hydroquinone solution as a polymerization terminator was added to terminate the polymerization reaction. Then, residual monomers were removed at a water temperature of 80° C. to obtain an aqueous dispersion of a polymer precursor.
The aqueous dispersion and palladium catalyst (1% palladium acetate in acetone solution) were placed in an autoclave so that the palladium content was 3,000 ppm based on the solid weight contained in the aqueous dispersion of the obtained polymer precursor. A solution prepared by mixing an equal weight of ion-exchanged water) was added, and a hydrogenation reaction was carried out at a hydrogen pressure of 3 MPa and a temperature of 55° C. for 3 hours to obtain an aqueous dispersion of the desired polymer (hydrogenated nitrile rubber).
Thereafter, the contents were returned to room temperature, the inside of the system was made into a nitrogen atmosphere, and then concentrated using an evaporator until the solid content concentration reached 40%.
Next, a 2.5% KOH aqueous solution was added to the concentrated aqueous polymer dispersion to adjust the pH to 9.5. The haze and iodine value were measured using the aqueous dispersion of the polymer after pH adjustment.
Add 200 parts of N-methylpyrrolidone to 100 parts of the aqueous dispersion of the polymer after pH adjustment, evaporate all water and residual monomers under reduced pressure, and then evaporate the N-methylpyrrolidone to obtain the binder composition. As a product, an 8% by mass NMP solution of the polymer was obtained. Using the obtained binder composition, the weight average molecular weight of the polymer and the amount of adsorption of the polymer to CNTs were measured and evaluated.
＜ＣＮＴ分散液の調製＞
　導電材としてのカーボンナノチューブ（比表面積：２８０ｍ２／ｇ、平均直径：５～１１ｎｍ、平均長さ：５～３０μｍ）４．０部と、上記で得られたバインダー組成物（重合体のＮＭＰ溶液）１．０６部（固形分換算量）と、得られるＣＮＴ分散液の総量が１００部となる量のＮＭＰとを、薄膜旋回型高速ミキサー（プライミクス社製「フィルミックス（登録商標） ４０－Ｌ型」）を用いて、周速２０ｍ／ｓで１２０秒間攪拌し、固形分濃度が５．０６質量％のＣＮＴ分散液を調製した。そして、得られたＣＮＴ分散液を用いて、遠心処理前後の比吸光度の変化率ΔＥ、ＣＮＴ分散液中のＣＮＴの体積平均粒子径Ｄ５０、ＣＮＴ分散液におけるＣＮＴの分散性、ＣＮＴ分散液の粘度安定性の評価を行った。 <Preparation of CNT dispersion>
4.0 parts of carbon nanotubes (specific surface area: 280 m 2 /g, average diameter: 5 to 11 nm, average length: 5 to 30 μm) as a conductive material and the binder composition obtained above (NMP solution of polymer) ) 1.06 parts (in terms of solid content) and NMP in an amount such that the total amount of the obtained CNT dispersion is 100 parts, were mixed in a thin film rotating high-speed mixer ("Filmix (registered trademark) 40-L" manufactured by Primix Co., Ltd.). A CNT dispersion liquid having a solid content concentration of 5.06% by mass was prepared by stirring for 120 seconds at a circumferential speed of 20 m/s. Using the obtained CNT dispersion, we determined the rate of change in specific absorbance ΔE before and after centrifugation, the volume average particle diameter D50 of CNT in the CNT dispersion, the dispersibility of CNT in the CNT dispersion, and the viscosity of the CNT dispersion. Stability was evaluated.
＜正極用スラリー組成物の調製＞
　正極活物質として層状構造を有する三元系活物質（ＬｉＮｉ0.6Ｃｏ0.2Ｍｎ0.2Ｏ2）（平均粒子径：１０μｍ）９８．０部と、結着材としてのポリフッ化ビニリデン１．０部と、上記で得られたＣＮＴ分散液１．０部（固形分換算量）と、ＮＭＰとを添加し、プラネタリーミキサーにて混合（６０ｒｐｍ、３０分）して、正極用スラリー組成物を調製した。なお、ＮＭＰの添加量は、得られる正極用スラリー組成物の粘度（ＪＩＳ Ｚ８８０３：１９９１に準じて単一円筒形回転粘度計により測定。温度：２５℃、回転数：６０ｒｐｍ）が４０００～５０００ｍＰａ・sの範囲内となるように調整した。 <Preparation of slurry composition for positive electrode>
98.0 parts of a ternary active material (LiNi 0.6 Co 0.2 Mn 0.2 O 2 ) (average particle size: 10 μm) having a layered structure as a positive electrode active material, and 1.0 part of polyvinylidene fluoride as a binder; 1.0 part (solid content equivalent) of the CNT dispersion obtained above and NMP were added and mixed in a planetary mixer (60 rpm, 30 minutes) to prepare a positive electrode slurry composition. The amount of NMP added is determined when the viscosity of the resulting positive electrode slurry composition (measured using a single cylindrical rotational viscometer according to JIS Z8803:1991, temperature: 25°C, rotation speed: 60 rpm) is 4000 to 5000 mPa. Adjusted to be within the range of s.
＜正極の作製＞
　集電体として、厚さ２０μｍのアルミ箔を準備した。上述のようにして得た正極用スラリーをコンマコーターでアルミ箔の片面に乾燥後の目付量が２０ｍｇ／ｃｍ2になるように塗布し、９０℃で２０分、１２０℃で２０分間乾燥後、６０℃で１０時間加熱処理して正極原反を得た。この正極原反をロールプレスで圧延し、密度が３．２ｇ／ｃｍ3の正極合材層とアルミ箔とからなるシート状の正極を作製した。そして、シート状の正極を幅４８．０ｍｍ、長さ４７ｃｍに切断して、リチウムイオン二次電池用正極とした。 <Preparation of positive electrode>
Aluminum foil with a thickness of 20 μm was prepared as a current collector. The positive electrode slurry obtained as described above was applied to one side of aluminum foil using a comma coater so that the drying weight was 20 mg/cm 2 , and after drying at 90°C for 20 minutes and at 120°C for 20 minutes, A positive electrode material was obtained by heat treatment at 60° C. for 10 hours. This positive electrode material was rolled with a roll press to produce a sheet-like positive electrode consisting of a positive electrode composite material layer having a density of 3.2 g/cm 3 and aluminum foil. Then, the sheet-like positive electrode was cut into pieces with a width of 48.0 mm and a length of 47 cm to obtain a positive electrode for a lithium ion secondary battery.
＜負極の作製＞
　撹拌機付き５ＭＰａ耐圧容器に、脂肪族共役ジエン単量体としての１，３－ブタジエン３３部、カルボン酸基含有単量体としてのイタコン酸３．５部、芳香族ビニル単量体としてのスチレン６３．５部、乳化剤としてのドデシルベンゼンスルホン酸ナトリウム０．４部、イオン交換水１５０部、及び、重合開始剤としての過硫酸カリウム０．５部を入れ、十分に撹拌した後、５０℃に加温して重合を開始した。重合転化率が９６％になった時点で冷却し重合反応を停止して、粒子状のバインダー（スチレン－ブタジエン共重合体）を含む混合物を得た。上記混合物に、５％水酸化ナトリウム水溶液を添加してｐＨ８に調整後、加熱減圧蒸留によって未反応単量体の除去を行った。その後、混合物を３０℃以下まで冷却し、負極用結着材を含む水分散液を得た。
　プラネタリーミキサーに、負極活物質としての人造黒鉛４８．７５部及び天然黒鉛４８．７５部、並びに増粘剤としてのカルボキシメチルセルロース１部（固形分相当）を投入した。さらに、イオン交換水にて固形分濃度が６０％となるように希釈し、その後、回転速度４５ｒｐｍで６０分混練した。その後、上述のようにして得た負極用結着材を含む水分散液を固形分相当で１．５部投入し、回転速度４０ｒｐｍで４０分混練した。そして、粘度が３０００±５００ｍＰａ・ｓ（Ｂ型粘度計、２５℃、６０ｒｐｍで測定）となるようにイオン交換水を加えることにより、負極用スラリー組成物を調製した。
　上記の負極用スラリー組成物を、コンマコーターで、集電体である厚さ１５μｍの銅箔の表面に、塗付量が１０±０．５ｍｇ／ｃｍ２となるように塗布した。その後、負極用スラリー組成物が塗布された銅箔を、４００ｍｍ／分の速度で、温度８０℃のオーブン内を２分間、さらに温度１１０℃のオーブン内を２分間かけて搬送することにより、銅箔上のスラリー組成物を乾燥させ、集電体上に負極合材層が形成された負極原反を得た。
　この負極原反をロールプレスで圧延し、密度が１．６ｇ／ｃｍ3の負極合材層とアルミ箔とからなるシート状負極を作製した。そして、シート状負極を幅５０．０ｍｍ、長さ５２ｃｍに切断して、リチウムイオン二次電池用負極とした。 <Preparation of negative electrode>
In a 5 MPa pressure vessel equipped with a stirrer, 33 parts of 1,3-butadiene as an aliphatic conjugated diene monomer, 3.5 parts of itaconic acid as a carboxylic acid group-containing monomer, and styrene as an aromatic vinyl monomer. Add 63.5 parts of sodium dodecylbenzenesulfonate as an emulsifier, 150 parts of ion-exchanged water, and 0.5 parts of potassium persulfate as a polymerization initiator, stir thoroughly, and then heat to 50°C. Polymerization was initiated by heating. When the polymerization conversion rate reached 96%, the polymerization reaction was stopped by cooling to obtain a mixture containing a particulate binder (styrene-butadiene copolymer). After adjusting the pH to 8 by adding a 5% aqueous sodium hydroxide solution to the above mixture, unreacted monomers were removed by heating and vacuum distillation. Thereafter, the mixture was cooled to 30° C. or lower to obtain an aqueous dispersion containing a negative electrode binder.
48.75 parts of artificial graphite and 48.75 parts of natural graphite as negative electrode active materials, and 1 part of carboxymethyl cellulose (equivalent to solid content) as a thickener were charged into a planetary mixer. Further, the mixture was diluted with ion-exchanged water to a solid concentration of 60%, and then kneaded for 60 minutes at a rotational speed of 45 rpm. Thereafter, 1.5 parts of the aqueous dispersion containing the negative electrode binder obtained as described above was added in terms of solid content, and kneaded at a rotational speed of 40 rpm for 40 minutes. Then, ion-exchanged water was added so that the viscosity was 3000±500 mPa·s (measured with a B-type viscometer, 25° C., 60 rpm) to prepare a slurry composition for a negative electrode.
The above slurry composition for a negative electrode was applied to the surface of a 15 μm thick copper foil serving as a current collector using a comma coater so that the coating amount was 10±0.5 mg/cm 2 . Thereafter, the copper foil coated with the negative electrode slurry composition was transported at a speed of 400 mm/min in an oven at a temperature of 80°C for 2 minutes, and then in an oven at a temperature of 110°C for 2 minutes. The slurry composition on the foil was dried to obtain a negative electrode original fabric in which a negative electrode composite layer was formed on the current collector.
This negative electrode material was rolled using a roll press to produce a sheet negative electrode consisting of a negative electrode composite material layer having a density of 1.6 g/cm 3 and aluminum foil. The sheet-like negative electrode was then cut into pieces with a width of 50.0 mm and a length of 52 cm to obtain a negative electrode for a lithium ion secondary battery.
＜接着層付きセパレータの作製＞
＜＜接着性重合体Ｂ１を含む水分散液の調製＞＞
　撹拌機を備えた反応器に、イオン交換水１００部、過硫酸アンモニウム０．５部を、それぞれ供給し、気相部を窒素ガスで置換し、７０℃に昇温した。一方、別の容器で、イオン交換水４０部、乳化剤としてのドデシルベンゼンスルホン酸ナトリウム０．３部、（メタ）アクリル酸エステル単量体としてのｎ－ブチルアクリレート２４．５部及びメチルメタクリレート２８部、ニトリル基含有単量体としてのアクリロニトリル１４部、酸基含有単量体としてのメタクリル酸（ＭＡＡ）２．８部、架橋性単量体としてのエチレングリコールジメタクリレート（ＥＤＭＡ）０．7部を混合して、コア部形成用単量体組成物を得た。この単量体組成物を３時間かけて前記反応器に連続的に添加して７０℃で重合反応を行った。重合転化率が９６％になるまで重合を継続させることにより、コア部を構成する粒子状の重合体を含む水分散液を得た。次いで、この水分散液を７５℃に加温し、当該水分散液に、ニトリル基含有単量体としてのアクリロニトリル１．７部、酸基含有単量体としてのメタクリル酸（ＭＡＡ）０．３部、芳香族含有単量体としてのスチレン（ＳＴ）２８．０部を混合し、連続添加して、重合を継続した。重合転化率が９６％になった時点で冷却して反応を停止することにより、接着性重合体Ｂ１を含む水分散液を得た。得られた接着性重合体Ｂ１は、コア部の外表面がシェル部で部分的に覆われたコアシェル構造を有していた。
＜＜接着性重合体Ｂ２を含む水分散液の調製＞＞
　撹拌機を備えた反応器に、イオン交換水７０部、乳化剤としてドデシルベンゼンスルホン酸ナトリウム０．２部、及び過流酸アンモニウム０．５部を、それぞれ供給し、気相部を窒素ガスで置換し、７５℃に昇温した。
　一方、別の容器でイオン交換水５０部、分散剤としてドデシルベンゼンスルホン酸ナトリウム０．８部、そして（メタ）アクリル酸エステル単量体としての２－エチルヘキシルアクリレート（２ＥＨＡ）７１．３部、酸基含有単量体としてのアクリル酸（ＡＡ）３．０部、エポキシ基含有単量体としてのアリルグリシジルエーテル１．７部、芳香族含有単量体としてのスチレン（ＳＴ）２６部、架橋性単量体としてのアリルメタクリレート（ＡＭＡ）０．２部を混合して単量体組成物を得た。この単量体組成物を４時間かけて前記反応器に連続的に添加して重合を行った。添加中は、７５℃で反応を行った。添加終了後、さらに８０℃で３時間撹拌して反応を終了し、接着性重合体Ｂ２を含む水分散液を得た。
＜＜接着層用スラリー組成物の調製＞＞
　接着性重合体Ｂ１の水分散液１００部（固形分相当）、接着性重合体Ｂ２の水分散液を１５部（固形分相当）と、イオン交換水を混合し、スラリー状の接着層用スラリー組成物（固形分濃度：１０％）を得た。
＜＜接着層の形成＞＞
　ポリエチレン製のセパレータ基材（旭化成社製、商品名「ＮＤ４１２」、厚さ：１２μｍ）を用意した。用意したセパレータ基材の表面に、セラミックススラリー（ＢＭ－２０００Ｍ、日本ゼオン製）を塗布し、温度５０℃下で３分間乾燥させ、片面に耐熱層を備えるセパレータ（耐熱層の厚み：２μｍ）を得た。続いて耐熱層を備えるセパレータの一方の面に、上記で得られた機能層用スラリー組成物を塗布し、温度５０℃下で３分間乾燥させた。同様の操作をセパレータ基材のもう一方の面にも施し、両面に接着層が形成された接着層付きセパレータを得た。乾燥後に両面で形成された接着層の目付量は０．２５ｇ／ｍ２であった。 <Production of separator with adhesive layer>
<<Preparation of aqueous dispersion containing adhesive polymer B1>>
100 parts of ion-exchanged water and 0.5 parts of ammonium persulfate were each supplied to a reactor equipped with a stirrer, the gas phase was replaced with nitrogen gas, and the temperature was raised to 70°C. Meanwhile, in another container, 40 parts of ion-exchanged water, 0.3 parts of sodium dodecylbenzenesulfonate as an emulsifier, 24.5 parts of n-butyl acrylate and 28 parts of methyl methacrylate as (meth)acrylic acid ester monomers. , 14 parts of acrylonitrile as a nitrile group-containing monomer, 2.8 parts of methacrylic acid (MAA) as an acid group-containing monomer, and 0.7 parts of ethylene glycol dimethacrylate (EDMA) as a crosslinkable monomer. By mixing, a monomer composition for forming a core portion was obtained. This monomer composition was continuously added to the reactor over 3 hours to conduct a polymerization reaction at 70°C. By continuing the polymerization until the polymerization conversion rate reached 96%, an aqueous dispersion containing a particulate polymer constituting the core portion was obtained. Next, this aqueous dispersion was heated to 75°C, and 1.7 parts of acrylonitrile as a nitrile group-containing monomer and 0.3 parts of methacrylic acid (MAA) as an acid group-containing monomer were added to the aqueous dispersion. and 28.0 parts of styrene (ST) as an aromatic monomer were mixed and continuously added to continue the polymerization. When the polymerization conversion rate reached 96%, the reaction was stopped by cooling to obtain an aqueous dispersion containing adhesive polymer B1. The obtained adhesive polymer B1 had a core-shell structure in which the outer surface of the core portion was partially covered with the shell portion.
<<Preparation of aqueous dispersion containing adhesive polymer B2>>
70 parts of ion-exchanged water, 0.2 parts of sodium dodecylbenzenesulfonate as an emulsifier, and 0.5 parts of ammonium persulfate were each supplied to a reactor equipped with a stirrer, and the gas phase was replaced with nitrogen gas. Then, the temperature was raised to 75°C.
Meanwhile, in another container, 50 parts of ion-exchanged water, 0.8 parts of sodium dodecylbenzenesulfonate as a dispersant, 71.3 parts of 2-ethylhexyl acrylate (2EHA) as a (meth)acrylate monomer, and acid 3.0 parts of acrylic acid (AA) as a group-containing monomer, 1.7 parts of allyl glycidyl ether as an epoxy group-containing monomer, 26 parts of styrene (ST) as an aromatic-containing monomer, crosslinkable A monomer composition was obtained by mixing 0.2 part of allyl methacrylate (AMA) as a monomer. This monomer composition was continuously added to the reactor over 4 hours to carry out polymerization. During the addition, the reaction was carried out at 75°C. After the addition was completed, the reaction was further stirred at 80° C. for 3 hours to complete the reaction, and an aqueous dispersion containing adhesive polymer B2 was obtained.
<<Preparation of slurry composition for adhesive layer>>
100 parts (equivalent to solid content) of an aqueous dispersion of adhesive polymer B1, 15 parts (equivalent to solid content) of an aqueous dispersion of adhesive polymer B2, and ion-exchanged water are mixed to form a slurry for an adhesive layer. A composition (solid content concentration: 10%) was obtained.
<<Formation of adhesive layer>>
A polyethylene separator base material (manufactured by Asahi Kasei Co., Ltd., trade name "ND412", thickness: 12 μm) was prepared. A ceramic slurry (BM-2000M, manufactured by Nippon Zeon) was applied to the surface of the prepared separator base material and dried at a temperature of 50°C for 3 minutes to form a separator with a heat-resistant layer on one side (heat-resistant layer thickness: 2 μm). Obtained. Subsequently, the slurry composition for a functional layer obtained above was applied to one side of the separator provided with the heat-resistant layer, and dried at a temperature of 50° C. for 3 minutes. The same operation was performed on the other side of the separator base material to obtain a separator with an adhesive layer in which adhesive layers were formed on both sides. After drying, the adhesive layer formed on both sides had a basis weight of 0.25 g/m 2 .
＜リチウムイオン二次電池の作製＞
　作製したリチウムイオン二次電池用正極とリチウムイオン二次電池用負極とを電極合剤層同士が向かい合うようにし、上記で作製した接着層付きセパレータを介在させて、直径２０ｍｍの芯を用いて捲回し、捲回体を得た。なお、上記操作において、接着層付きセパレータは、耐熱層の上に接着層が更に形成された側の面が正極と向かい合うように配置した。そして、得られた捲回体を、１０ｍｍ／秒の速度で厚さ４．５ｍｍになるまで一方向から圧縮した。なお、圧縮後の捲回体は平面視楕円形をしており、その長径と短径との比（長径／短径）は７．７であった。
　また、電解液として濃度１．０ＭのＬｉＰＦ６溶液（溶媒：エチレンカーボネート（ＥＣ）／ジエチルカーボネート（ＤＥＣ）＝３／７（体積比）の混合溶媒、添加剤：ビニレンカーボネート２体積％（溶媒比）含有）を準備した。
　その後、圧縮後の捲回体をアルミ製ラミネートケース内に３．２ｇの電解液とともに収容した。そして、二次電池用負極の所定の箇所にニッケルリード線を接続し、二次電池用正極の所定の箇所にアルミニウムリード線を接続したのち、ケースの開口部を熱で封口し、本発明の電気化学素子としてのリチウムイオン二次電池を得た。このリチウムイオン二次電池は、幅３５ｍｍ、高さ６０ｍｍ、厚さ５ｍｍのパウチ形であり、電池の公称容量は７００ｍＡｈであった。
　得られたリチウムイオン二次電池について、サイクル特性及び高温保存特性を評価した。結果を表１に示す。 <Production of lithium ion secondary battery>
The prepared positive electrode for a lithium ion secondary battery and the negative electrode for a lithium ion secondary battery were placed so that the electrode mixture layers faced each other, and the separator with the adhesive layer prepared above was interposed and wound using a core with a diameter of 20 mm. Turn it to obtain a rolled body. In the above operation, the separator with an adhesive layer was placed so that the surface on which the adhesive layer was further formed on the heat-resistant layer faced the positive electrode. Then, the obtained wound body was compressed from one direction at a speed of 10 mm/sec until it had a thickness of 4.5 mm. The wound body after compression had an elliptical shape in plan view, and the ratio of the major axis to the minor axis (major axis/minor axis) was 7.7.
In addition, as an electrolyte, LiPF 6 solution with a concentration of 1.0 M (solvent: mixed solvent of ethylene carbonate (EC)/diethyl carbonate (DEC) = 3/7 (volume ratio), additive: vinylene carbonate 2% by volume (solvent ratio) ) was prepared.
Thereafter, the compressed wound body was housed in an aluminum laminate case together with 3.2 g of electrolyte. After connecting a nickel lead wire to a predetermined location on the negative electrode for a secondary battery and an aluminum lead wire to a predetermined location on the positive electrode for a secondary battery, the opening of the case is sealed with heat. A lithium ion secondary battery as an electrochemical device was obtained. This lithium ion secondary battery was in the form of a pouch with a width of 35 mm, a height of 60 mm, and a thickness of 5 mm, and the nominal capacity of the battery was 700 mAh.
The cycle characteristics and high temperature storage characteristics of the obtained lithium ion secondary battery were evaluated. The results are shown in Table 1.
（実施例２～３）
　実施例１の重合体（バインダー組成物）の調製の際に、ニトリル基含有単量体としてのアクリロニトリル、親水性基含有単量体としてのメタクリル酸、及び、共役ジエン単量体としての１，３－ブタジエンの各々の添加量を、得られる重合体の組成が表１に示す通りになるように変更したこと以外は、実施例１と同様にして、重合体（バインダー組成物）の調製、ＣＮＴ分散液の調製、正極用スラリー組成物の調製、正極の作製、負極の作製、接着層付きセパレータの作製、リチウムイオン二次電池の作製を行い、各種の測定及び評価を行った。結果を表１に示す。 (Examples 2-3)
When preparing the polymer (binder composition) of Example 1, acrylonitrile as a nitrile group-containing monomer, methacrylic acid as a hydrophilic group-containing monomer, and 1, as a conjugated diene monomer. Preparation of a polymer (binder composition) in the same manner as in Example 1, except that the amount of each of 3-butadiene added was changed so that the composition of the resulting polymer was as shown in Table 1. A CNT dispersion liquid, a positive electrode slurry composition, a positive electrode, a negative electrode, a separator with an adhesive layer, and a lithium ion secondary battery were prepared, and various measurements and evaluations were performed. The results are shown in Table 1.
（実施例４）
　実施例１の重合体（バインダー組成物）の調製の際に、連鎖移動剤としてのｔ－ドデシルメルカプタンの添加量を２．５０部から０．４部に変更したこと以外は、実施例１と同様にして、重合体（バインダー組成物）の調製、ＣＮＴ分散液の調製、正極用スラリー組成物の調製、正極の作製、負極の作製、接着層付きセパレータの作製、リチウムイオン二次電池の作製を行い、各種の測定及び評価を行った。結果を表１に示す。 (Example 4)
The same procedure as that of Example 1 was performed except that the amount of t-dodecyl mercaptan added as a chain transfer agent was changed from 2.50 parts to 0.4 parts during the preparation of the polymer (binder composition) of Example 1. Similarly, preparation of polymer (binder composition), preparation of CNT dispersion, preparation of slurry composition for positive electrode, preparation of positive electrode, preparation of negative electrode, preparation of separator with adhesive layer, preparation of lithium ion secondary battery. We carried out various measurements and evaluations. The results are shown in Table 1.
（実施例５）
　実施例１の重合体（バインダー組成物）の調製の際に、パラジウム触媒の添加量を調整して、重合体の前駆体の水分散液に含有される固形分重量に対するパラジウム含有量を３，０００ｐｐｍから１，５００ｐｐｍに変更したこと以外は、実施例１と同様にして、重合体（バインダー組成物）の調製、ＣＮＴ分散液の調製、正極用スラリー組成物の調製、正極の作製、負極の作製、接着層付きセパレータの作製、リチウムイオン二次電池の作製を行い、各種の測定及び評価を行った。結果を表１に示す。 (Example 5)
During the preparation of the polymer (binder composition) of Example 1, the amount of palladium catalyst added was adjusted so that the palladium content was 3. Except for changing the amount from 000 ppm to 1,500 ppm, the same procedures as in Example 1 were carried out, including preparation of a polymer (binder composition), preparation of a CNT dispersion, preparation of a slurry composition for a positive electrode, production of a positive electrode, and preparation of a negative electrode. A separator with an adhesive layer was manufactured, a lithium ion secondary battery was manufactured, and various measurements and evaluations were performed. The results are shown in Table 1.
（実施例６）
　実施例１の重合体（バインダー組成物）の調製の際に、ニトリル基含有単量体としてのアクリロニトリルの添加量を３０部から２５部に変更し、共役ジエン単量体としての１，３－ブタジエンの添加量を６０部から５５部に変更し、（メタ）アクリル酸エステル単量体としてのメタクリル酸メチル１０部を更に添加したこと以外は、実施例１と同様にして、重合体（バインダー組成物）の調製、ＣＮＴ分散液の調製、正極用スラリー組成物の調製、正極の作製、負極の作製、接着層付きセパレータの作製、リチウムイオン二次電池の作製を行い、各種の測定及び評価を行った。結果を表１に示す。 (Example 6)
When preparing the polymer (binder composition) of Example 1, the amount of acrylonitrile added as a nitrile group-containing monomer was changed from 30 parts to 25 parts, and the amount of 1,3- as a conjugated diene monomer was changed from 30 parts to 25 parts. The polymer (binder composition), preparation of CNT dispersion, preparation of slurry composition for positive electrode, preparation of positive electrode, preparation of negative electrode, preparation of separator with adhesive layer, preparation of lithium ion secondary battery, and various measurements and evaluations. I did it. The results are shown in Table 1.
（実施例７）
　実施例１の重合体（バインダー組成物）の調製の際に、ニトリル基含有単量体としてのアクリロニトリルの添加量を３０部から２５部に変更し、共役ジエン単量体としての１，３－ブタジエンの添加量を６０部から５５部に変更し、芳香族ビニル単量体としてのスチレン１０部を更に添加したこと以外は、実施例１と同様にして、重合体（バインダー組成物）の調製、ＣＮＴ分散液の調製、正極用スラリー組成物の調製、正極の作製、負極の作製、接着層付きセパレータの作製、リチウムイオン二次電池の作製を行い、各種の測定及び評価を行った。結果を表１に示す。 (Example 7)
When preparing the polymer (binder composition) of Example 1, the amount of acrylonitrile added as a nitrile group-containing monomer was changed from 30 parts to 25 parts, and the amount of 1,3- as a conjugated diene monomer was changed from 30 parts to 25 parts. A polymer (binder composition) was prepared in the same manner as in Example 1, except that the amount of butadiene added was changed from 60 parts to 55 parts, and 10 parts of styrene as an aromatic vinyl monomer was further added. , prepared a CNT dispersion, prepared a slurry composition for a positive electrode, produced a positive electrode, produced a negative electrode, produced a separator with an adhesive layer, and produced a lithium ion secondary battery, and conducted various measurements and evaluations. The results are shown in Table 1.
（比較例１）
　実施例１の重合体（バインダー組成物）の調製の際に、ニトリル基含有単量体としてのアクリロニトリルの添加量を３０部から３５部に変更し、親水性基含有単量体としてのメタクリル酸の添加量を１０部から５部に変更し、連鎖移動剤としてのｔ－ドデシルメルカプタンの添加量を２．５０部から１．２０部に変更し、さらに、パラジウム触媒の添加量を調整して、重合体の前駆体の水分散液に含有される固形分重量に対するパラジウム含有量を３，０００ｐｐｍから８００ｐｐｍに変更したこと以外は、実施例１と同様にして、重合体（バインダー組成物）の調製、ＣＮＴ分散液の調製、正極用スラリー組成物の調製、正極の作製、負極の作製、接着層付きセパレータの作製、リチウムイオン二次電池の作製を行い、各種の測定及び評価を行った。結果を表１に示す。 (Comparative example 1)
When preparing the polymer (binder composition) of Example 1, the amount of acrylonitrile added as a nitrile group-containing monomer was changed from 30 parts to 35 parts, and the amount of methacrylic acid as a hydrophilic group-containing monomer was changed from 30 parts to 35 parts. The amount of addition was changed from 10 parts to 5 parts, the amount of t-dodecyl mercaptan as a chain transfer agent was changed from 2.50 parts to 1.20 parts, and the amount of palladium catalyst added was adjusted. A polymer (binder composition) was prepared in the same manner as in Example 1, except that the palladium content relative to the solid weight contained in the aqueous dispersion of the polymer precursor was changed from 3,000 ppm to 800 ppm. A CNT dispersion was prepared, a positive electrode slurry composition was prepared, a positive electrode was prepared, a negative electrode was prepared, a separator with an adhesive layer was prepared, a lithium ion secondary battery was prepared, and various measurements and evaluations were performed. The results are shown in Table 1.
（比較例２）
　実施例１の重合体（バインダー組成物）の調製の際に、ニトリル基含有単量体としてのアクリロニトリルの添加量を３０部から３５部に変更し、共役ジエン単量体としての１，３－ブタジエンの添加量を６０部から６５部に変更し、親水性基含有単量体としてのメタクリル酸を添加せず、連鎖移動剤としてのｔ－ドデシルメルカプタンの添加量を２．５０部から１．８０部に変更し、さらに、パラジウム触媒の添加量を調整して、重合体の前駆体の水分散液に含有される固形分重量に対するパラジウム含有量を３，０００ｐｐｍから５００ｐｐｍに変更したこと以外は、実施例１と同様にして、重合体（バインダー組成物）の調製、ＣＮＴ分散液の調製、正極用スラリー組成物の調製、正極の作製、負極の作製、接着層付きセパレータの作製、リチウムイオン二次電池の作製を行い、各種の測定及び評価を行った。結果を表１に示す。 (Comparative example 2)
When preparing the polymer (binder composition) of Example 1, the amount of acrylonitrile added as a nitrile group-containing monomer was changed from 30 parts to 35 parts, and the amount of 1,3- as a conjugated diene monomer was changed from 30 parts to 35 parts. The amount of butadiene added was changed from 60 parts to 65 parts, methacrylic acid as a hydrophilic group-containing monomer was not added, and the amount of t-dodecyl mercaptan added as a chain transfer agent was changed from 2.50 parts to 1. 80 parts, and further adjusted the amount of palladium catalyst added to change the palladium content from 3,000 ppm to 500 ppm based on the solid weight contained in the aqueous dispersion of the polymer precursor. , Preparation of polymer (binder composition), preparation of CNT dispersion, preparation of slurry composition for positive electrode, preparation of positive electrode, preparation of negative electrode, preparation of separator with adhesive layer, preparation of lithium ion in the same manner as in Example 1. A secondary battery was manufactured and various measurements and evaluations were performed. The results are shown in Table 1.
（比較例３）
　実施例１の重合体（バインダー組成物）の調製の際に、連鎖移動剤としてのｔ－ドデシルメルカプタンの添加量を２．５０部から０．２０部に変更し、さらに、パラジウム触媒の添加量を調整して、重合体の前駆体の水分散液に含有される固形分重量に対するパラジウム含有量を３，０００ｐｐｍから１,０００ｐｐｍに変更したこと以外は、実施例１と同様にして、重合体（バインダー組成物）の調製、ＣＮＴ分散液の調製、正極用スラリー組成物の調製、正極の作製、負極の作製、接着層付きセパレータの作製、リチウムイオン二次電池の作製を行い、各種の測定及び評価を行った。結果を表１に示す。 (Comparative example 3)
When preparing the polymer (binder composition) of Example 1, the amount of t-dodecyl mercaptan added as a chain transfer agent was changed from 2.50 parts to 0.20 parts, and the amount of palladium catalyst added was changed from 2.50 parts to 0.20 parts. A polymer was prepared in the same manner as in Example 1, except that the palladium content was changed from 3,000 ppm to 1,000 ppm based on the solid weight contained in the aqueous dispersion of the polymer precursor. (binder composition), CNT dispersion, slurry composition for positive electrode, positive electrode, negative electrode, separator with adhesive layer, lithium ion secondary battery, and various measurements. and evaluated. The results are shown in Table 1.
（比較例４）
　実施例１のＣＮＴ分散液の調製の際に、薄膜旋回型高速ミキサー（プライミクス社製「フィルミックス（登録商標） ４０－Ｌ型」）用いた攪拌時間を１２０秒間から１０秒間に変更したこと以外は、実施例１と同様にして、重合体（バインダー組成物）の調製、ＣＮＴ分散液の調製、正極用スラリー組成物の調製、正極の作製、負極の作製、接着層付きセパレータの作製、リチウムイオン二次電池の作製を行い、各種の測定及び評価を行った。結果を表１に示す。 (Comparative example 4)
Except that when preparing the CNT dispersion liquid in Example 1, the stirring time using a thin film rotating high-speed mixer ("Filmix (registered trademark) 40-L type" manufactured by Primix Corporation) was changed from 120 seconds to 10 seconds. In the same manner as in Example 1, preparation of a polymer (binder composition), preparation of a CNT dispersion, preparation of a slurry composition for a positive electrode, preparation of a positive electrode, preparation of a negative electrode, preparation of a separator with an adhesive layer, and preparation of a lithium An ion secondary battery was fabricated, and various measurements and evaluations were performed. The results are shown in Table 1.
（比較例５）
　実施例１の重合体（バインダー組成物）の調製の際に、ニトリル基含有単量体としてのアクリロニトリルの添加量を３０部から３５部に変更し、親水性基含有単量体としてのメタクリル酸の添加量を１０部から５部に変更し、連鎖移動剤としてのｔ－ドデシルメルカプタンの添加量を２．５０部から１．５部に変更し、さらに、パラジウム触媒の添加量を調整して、重合体の前駆体の水分散液に含有される固形分重量に対するパラジウム含有量を３，０００ｐｐｍから３００ｐｐｍに変更し、さらに、実施例１のＣＮＴ分散液の調製の際に、薄膜旋回型高速ミキサー（プライミクス社製「フィルミックス（登録商標） ４０－Ｌ型」）に代えて、直径１ｍｍのジルコニアビーズを用いたビーズミルを使用し、周速８ｍ／ｓにて３６００秒間混合を行ったこと以外は、実施例１と同様にして、重合体（バインダー組成物）の調製、ＣＮＴ分散液の調製、正極用スラリー組成物の調製、正極の作製、負極の作製、接着層付きセパレータの作製、リチウムイオン二次電池の作製を行い、各種の測定及び評価を行った。結果を表１に示す。 (Comparative example 5)
When preparing the polymer (binder composition) of Example 1, the amount of acrylonitrile added as a nitrile group-containing monomer was changed from 30 parts to 35 parts, and the amount of methacrylic acid as a hydrophilic group-containing monomer was changed from 30 parts to 35 parts. The amount of t-dodecyl mercaptan added as a chain transfer agent was changed from 2.50 parts to 1.5 parts, and the amount of palladium catalyst added was adjusted. , the palladium content based on the solid weight contained in the aqueous dispersion of the polymer precursor was changed from 3,000 ppm to 300 ppm, and further, during the preparation of the CNT dispersion of Example 1, a thin film rotating high-speed Except that a bead mill using zirconia beads with a diameter of 1 mm was used instead of a mixer ("Filmix (registered trademark) 40-L type" manufactured by Primix), and mixing was performed for 3600 seconds at a peripheral speed of 8 m/s. In the same manner as in Example 1, preparation of a polymer (binder composition), preparation of a CNT dispersion, preparation of a slurry composition for a positive electrode, preparation of a positive electrode, preparation of a negative electrode, preparation of a separator with an adhesive layer, and preparation of a lithium An ion secondary battery was fabricated, and various measurements and evaluations were performed. The results are shown in Table 1.
（比較例６）
　実施例１の重合体（バインダー組成物）の調製の際に、連鎖移動剤としてのｔ－ドデシルメルカプタンの添加量を２．５０部から２．００部に変更し、さらに、実施例１のＣＮＴ分散液の調製の際に、薄膜旋回型高速ミキサー（プライミクス社製「フィルミックス（登録商標） ４０－Ｌ型」）に代えて、直径１ｍｍのジルコニアビーズを用いたビーズミルを使用し、周速８ｍ／ｓにて３６００秒間混合を行ったこと以外は、実施例１と同様にして、重合体（バインダー組成物）の調製、ＣＮＴ分散液の調製、正極用スラリー組成物の調製、正極の作製、負極の作製、接着層付きセパレータの作製、リチウムイオン二次電池の作製を行い、各種の測定及び評価を行った。結果を表１に示す。 (Comparative example 6)
When preparing the polymer (binder composition) of Example 1, the amount of t-dodecyl mercaptan added as a chain transfer agent was changed from 2.50 parts to 2.00 parts, and the CNT of Example 1 was further added. When preparing the dispersion liquid, a bead mill using zirconia beads with a diameter of 1 mm was used instead of a thin film swirling type high-speed mixer ("Filmix (registered trademark) 40-L type" manufactured by Primix), and a peripheral speed of 8 m was used. Preparation of polymer (binder composition), preparation of CNT dispersion, preparation of positive electrode slurry composition, preparation of positive electrode, in the same manner as in Example 1 except that mixing was performed for 3600 seconds at /s A negative electrode, a separator with an adhesive layer, and a lithium ion secondary battery were manufactured, and various measurements and evaluations were performed. The results are shown in Table 1.
　なお、表１中、「Ｆｉｌｍｉｘ」は、プライミクス社製「フィルミックス（登録商標） ４０－Ｌ型」を意味する。 In Table 1, "Filmix" means "Filmix (registered trademark) 40-L type" manufactured by Primix Corporation.
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
　表１より、カーボンナノチューブと、所定の重合体と、分散媒とを含み、遠心処理前後の比吸光度の変化率ΔＥの値が所定値未満である実施例１～７のＣＮＴ分散液は、遠心処理前後の比吸光度の変化率ΔＥの値が所定値以上である比較例１～６のＣＮＴ分散液と比較して、ＣＮＴの分散性に優れていることが分かる。 From Table 1, the CNT dispersions of Examples 1 to 7, which contain carbon nanotubes, a predetermined polymer, and a dispersion medium, and in which the value of the change rate ΔE of specific absorbance before and after centrifugation treatment is less than a predetermined value, are It can be seen that the dispersibility of CNTs is excellent compared to the CNT dispersions of Comparative Examples 1 to 6 in which the value of the change rate ΔE of specific absorbance before and after treatment is equal to or greater than a predetermined value.
　本発明によれば、カーボンナノチューブの分散性に優れたカーボンナノチューブ分散液を提供することができる。
　また、本発明によれば、当該カーボンナノチューブ分散液を用いて調製した非水系二次電池電極用スラリー組成物を提供することができる。
　さらに、本発明によれば、当該非水系二次電池電極用スラリー組成物を用いて形成した非水系二次電池用電極を提供することができる。
　また、本発明によれば、当該非水系二次電池用電極を備える非水系二次電池を提供することができる。 According to the present invention, it is possible to provide a carbon nanotube dispersion liquid with excellent dispersibility of carbon nanotubes.
Further, according to the present invention, it is possible to provide a slurry composition for a non-aqueous secondary battery electrode prepared using the carbon nanotube dispersion.
Furthermore, according to the present invention, it is possible to provide an electrode for a non-aqueous secondary battery formed using the slurry composition for a non-aqueous secondary battery electrode.
Further, according to the present invention, it is possible to provide a non-aqueous secondary battery including the non-aqueous secondary battery electrode.

Claims (13)

  1. 　カーボンナノチューブ、重合体、及び分散媒を含むカーボンナノチューブ分散液であって、
    　前記重合体が、ニトリル基含有単量体単位と、アルキレン構造単位と、親水性基含有単量体単位とを含有し、
    　前記カーボンナノチューブ分散液の比吸光度をＥ１とし、前記カーボンナノチューブ分散液を４０００ｒｐｍで１分間遠心処理して得られる上澄み液の比吸光度をＥ２とした場合に、式：ΔＥ＝１００×（Ｅ１－Ｅ２）／Ｅ１［％］により得られる遠心処理前後の比吸光度の変化率ΔＥが５０％未満である、カーボンナノチューブ分散液。     A carbon nanotube dispersion liquid comprising carbon nanotubes, a polymer, and a dispersion medium,
    The polymer contains a nitrile group-containing monomer unit, an alkylene structural unit, and a hydrophilic group-containing monomer unit,
    When the specific absorbance of the carbon nanotube dispersion is E1 and the specific absorbance of the supernatant obtained by centrifuging the carbon nanotube dispersion at 4000 rpm for 1 minute is E2, the formula: ΔE=100×(E1-E2 )/E1 [%] A carbon nanotube dispersion liquid in which the rate of change ΔE in specific absorbance before and after centrifugation is less than 50%.
  2. 　前記重合体の重量平均分子量が２，０００以上２００，０００以下である、請求項１に記載のカーボンナノチューブ分散液。 The carbon nanotube dispersion according to claim 1, wherein the weight average molecular weight of the polymer is 2,000 or more and 200,000 or less.
  3. 　前記重合体の８質量％水溶液のヘイズがｐＨ８．０以上において７０％以下である、請求項１に記載のカーボンナノチューブ分散液。 The carbon nanotube dispersion according to claim 1, wherein the haze of the 8% by mass aqueous solution of the polymer is 70% or less at pH 8.0 or higher.
  4. 　前記重合体中のアルキレン構造単位及び共役ジエン単量体単位の合計含有割合が、３０質量％以上８０質量％以下である、請求項１に記載のカーボンナノチューブ分散液。 The carbon nanotube dispersion according to claim 1, wherein the total content of alkylene structural units and conjugated diene monomer units in the polymer is 30% by mass or more and 80% by mass or less.
  5. 　前記重合体のヨウ素価が、５ｍｇ／１００ｍｇ以上１００ｍｇ／１００ｍｇ以下である、請求項１に記載のカーボンナノチューブ分散液。 The carbon nanotube dispersion liquid according to claim 1, wherein the iodine value of the polymer is 5 mg/100 mg or more and 100 mg/100 mg or less.
  6. 　前記重合体中のニトリル基含有単量体単位の含有割合が１０質量％以上５５質量％以下である、請求項１に記載のカーボンナノチューブ分散液。 The carbon nanotube dispersion according to claim 1, wherein the content of the nitrile group-containing monomer unit in the polymer is 10% by mass or more and 55% by mass or less.
  7. 　前記カーボンナノチューブの体積平均粒子径Ｄ５０の値が、０．１μｍ以上１５．０μｍ以下である、請求項１に記載のカーボンナノチューブ分散液。 The carbon nanotube dispersion according to claim 1, wherein the carbon nanotubes have a volume average particle diameter D50 of 0.1 μm or more and 15.0 μm or less.
  8. 　前記重合体中の親水性基含有単量体単位の含有割合が６．５質量％以上５０質量％以下である、請求項１に記載のカーボンナノチューブ分散液。 The carbon nanotube dispersion according to claim 1, wherein the content of hydrophilic group-containing monomer units in the polymer is 6.5% by mass or more and 50% by mass or less.
  9. 　前記重合体が（メタ）アクリル酸エステル単量体単位を含有しない、請求項１に記載のカーボンナノチューブ分散液。 The carbon nanotube dispersion according to claim 1, wherein the polymer does not contain a (meth)acrylic acid ester monomer unit.
  10. 　前記重合体が芳香族ビニル単量体単位を含有しない、請求項１に記載のカーボンナノチューブ分散液。 The carbon nanotube dispersion according to claim 1, wherein the polymer does not contain aromatic vinyl monomer units.
  11. 　電極活物質と、請求項１～１０のいずれかに記載のカーボンナノチューブ分散液とを含む、非水系二次電池電極用スラリー組成物。 A slurry composition for a non-aqueous secondary battery electrode, comprising an electrode active material and the carbon nanotube dispersion according to any one of claims 1 to 10.
  12. 　請求項１１に記載の非水系二次電池電極用スラリー組成物を用いて形成した電極合材層を備える、非水系二次電池用電極。 An electrode for a non-aqueous secondary battery, comprising an electrode mixture layer formed using the slurry composition for a non-aqueous secondary battery electrode according to claim 11.
  13. 　請求項１２に記載の非水系二次電池用電極を備える、非水系二次電池。 A non-aqueous secondary battery comprising the non-aqueous secondary battery electrode according to claim 12.
PCT/JP2023/030040 2022-08-31 2023-08-21 Carbon nanotube dispersion, slurry composition for nonaqueous secondary battery electrode, electrode for nonaqueous secondary battery, and nonaqueous secondary battery WO2024048354A1 (en)

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Citations (4)

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Publication number Priority date Publication date Assignee Title
JP2018534220A (en) * 2015-09-25 2018-11-22 エルジー・ケム・リミテッド Carbon nanotube dispersion and method for producing the same
WO2021200126A1 (en) * 2020-03-30 2021-10-07 日本ゼオン株式会社 Conductive material dispersion liquid, slurry for secondary battery positive electrodes, positive electrode for secodnary batteries, and secondary battery
JP2022041230A (en) * 2020-08-31 2022-03-11 日本ゼオン株式会社 Conductive material dispersion for electrochemical element, slurry for electrochemical element electrode, electrode for electrochemical element, and electrochemical element
WO2022070736A1 (en) * 2020-09-29 2022-04-07 日本ゼオン株式会社 Conductive material dispersion liquid, method for producing slurry for nonaqueous secondary battery positive electrodes, method for producing positive electrode for nonaqueous secondary batteries, and method for producing nonaqueous secondary battery

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2018534220A (en) * 2015-09-25 2018-11-22 エルジー・ケム・リミテッド Carbon nanotube dispersion and method for producing the same
WO2021200126A1 (en) * 2020-03-30 2021-10-07 日本ゼオン株式会社 Conductive material dispersion liquid, slurry for secondary battery positive electrodes, positive electrode for secodnary batteries, and secondary battery
JP2022041230A (en) * 2020-08-31 2022-03-11 日本ゼオン株式会社 Conductive material dispersion for electrochemical element, slurry for electrochemical element electrode, electrode for electrochemical element, and electrochemical element
WO2022070736A1 (en) * 2020-09-29 2022-04-07 日本ゼオン株式会社 Conductive material dispersion liquid, method for producing slurry for nonaqueous secondary battery positive electrodes, method for producing positive electrode for nonaqueous secondary batteries, and method for producing nonaqueous secondary battery

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