WO2014024823A1 - Slurry and negative electrode for lithium ion batteries - Google Patents

Slurry and negative electrode for lithium ion batteries Download PDF

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Publication number
WO2014024823A1
WO2014024823A1 PCT/JP2013/071116 JP2013071116W WO2014024823A1 WO 2014024823 A1 WO2014024823 A1 WO 2014024823A1 JP 2013071116 W JP2013071116 W JP 2013071116W WO 2014024823 A1 WO2014024823 A1 WO 2014024823A1
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Prior art keywords
ethylenically unsaturated
negative electrode
lithium ion
ion battery
particles
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PCT/JP2013/071116
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French (fr)
Japanese (ja)
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村田　浩一
石井　伸晃
武内　正隆
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昭和電工株式会社
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Priority to JP2013548654A priority Critical patent/JPWO2014024823A1/en
Publication of WO2014024823A1 publication Critical patent/WO2014024823A1/en

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • 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
    • H01M4/133—Electrodes based on carbonaceous material, e.g. graphite-intercalation compounds or CFx
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • 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
    • H01M4/134—Electrodes based on metals, Si or alloys
    • 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
    • H01M4/1393—Processes of manufacture of electrodes based on carbonaceous material, e.g. graphite-intercalation compounds or CFx
    • 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
    • H01M4/1395—Processes of manufacture of electrodes based on metals, Si or alloys
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/362—Composites
    • H01M4/364—Composites as mixtures
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/38—Selection of substances as active materials, active masses, active liquids of elements or alloys
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/38—Selection of substances as active materials, active masses, active liquids of elements or alloys
    • H01M4/386—Silicon or alloys based on 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
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/38—Selection of substances as active materials, active masses, active liquids of elements or alloys
    • H01M4/387—Tin or alloys based on tin
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • H01M4/621—Binders
    • H01M4/622—Binders being polymers
    • 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 slurry. More specifically, the present invention relates to a slurry capable of obtaining a lithium ion battery having a large charge / discharge capacity and good charge / discharge cycle characteristics, a negative electrode formed by applying the slurry, and a lithium ion battery having the negative electrode.
  • This application claims priority based on Japanese Patent Application No. 2012-176401 for which it applied to Japan on August 8, 2012, and uses the content here.
  • the power consumption of portable electronic devices is increasing because the multifunction of portable electronic devices is progressing faster than the power saving of electronic components. Therefore, higher capacity and smaller size of the lithium ion battery, which is the main power source of portable electronic devices, are more strongly demanded than ever. In addition, the demand for electric vehicles is increasing, and the lithium-ion batteries used there are also strongly required to have a high capacity.
  • the theoretical capacity of a lithium ion battery when Si-containing particles are used as the negative electrode material is 4200 mAh / g. Since the theoretical capacity of a lithium battery using metal lithium is 3900 mAh / g, if Si or the like can be used as a negative electrode material, it is expected that a lithium ion battery having a smaller size and higher capacity than a metal lithium battery can be obtained.
  • a negative electrode material such as Si has a large expansion coefficient and contraction coefficient associated with insertion / extraction (occlusion / release) of lithium ions.
  • the organic solvent N-methyl-pyrrolidone (NMP) is used as a binder for binding the active material to the current collector, and the resin itself has high swelling resistance to the electrolyte solution.
  • Vinylidene chloride (PVDF) has been used.
  • this organic solvent-based binder has a low binding property between active materials and between an active material and a current collector, and a large amount of binder is required to obtain an effective binding force, resulting in the capacity of a lithium ion battery.
  • the energy density is lowered.
  • the organic solvent-based binder uses NMP, which is an expensive organic solvent, in the solvent, so that the price of the final product is high.
  • SBR styrene-butadiene rubber
  • CMC carboxymethyl cellulose
  • Patent Document 1 As a binder for an anode of an alloy containing Si or the like, which is expected to have a large capacity, it is known that the cycle characteristics of a binder using an aqueous binder are remarkably improved as compared with the case of using PVDF (for example, non-binding).
  • PVDF for example, non-binding
  • the object of the present invention is to use a water-dispersed binder, have good binding properties between active materials and between an active material and a current collector, have a large charge / discharge capacity, high charge / discharge efficiency, and charge / discharge cycle characteristics. It is an object to provide an alloy-based slurry, a negative electrode obtained using the slurry, and a lithium ion battery having the negative electrode, which can provide a lithium ion battery to be improved.
  • a negative electrode material for a lithium ion battery containing, as an active material, particles A containing at least one element selected from the group consisting of Si, Sn, Ge, and In, Obtained by polymerizing an ethylenically unsaturated monomer containing styrene, an ethylenically unsaturated carboxylic acid ester, an ethylenically unsaturated carboxylic acid, and a crosslinking agent having at least one ethylenically unsaturated group as essential components
  • a negative electrode material for a lithium ion battery containing, as an active material, particles A containing at least one element selected from the group consisting of Si, Sn, Ge, and In; Obtained by polymerizing an ethylenically unsaturated monomer containing styrene, an ethylenically unsaturated carboxylic acid ester, an ethylenically unsaturated carboxylic acid, and a crosslinking agent having at least one ethylenically unsaturated group as essential components
  • a negative electrode material for a lithium ion battery containing, as an active material, particles A containing at least one element selected from the group consisting of Si, Sn, Ge, and In; Presence of surfactant with ethylenically unsaturated monomer containing styrene, ethylenically unsaturated carboxylic acid ester, ethylenically unsaturated carboxylic acid, and crosslinking agent having at least one ethylenically unsaturated group as essential components
  • the manufacturing method of a slurry including the process of mixing below with the aqueous emulsion containing the polymer B obtained by superposition
  • the slurry of the present invention By using the slurry of the present invention, it is possible to obtain a lithium ion battery having good binding properties between the active materials and between the active material and the current collector and improving the charge / discharge cycle characteristics using the water dispersion binder. Moreover, the lithium ion battery obtained using the slurry for lithium ion battery negative electrodes of this invention has a large charge / discharge capacity compared with what was produced using the conventional aqueous binder, and is excellent in charge / discharge efficiency.
  • Example 1 shows the cycle characteristics in Example 1 and Comparative Example 1. It is a schematic diagram which shows the lithium ion battery which concerns on one Embodiment of this invention.
  • the negative electrode material used for the slurry according to one embodiment of the present invention includes, as an active material, particles A containing at least one element selected from the group consisting of Si, Sn, Ge, and In.
  • the particle A which is one of the constituent materials of the negative electrode material according to one embodiment of the present invention contains at least one element selected from the group consisting of Si, Sn, Ge and In. Of these elements, Si or Sn is preferable.
  • the particle A may be composed of a simple substance of these elements or a compound containing these elements, or may be composed of a compound, a mixture, a eutectic or a solid solution containing at least two of these elements. Good.
  • the particle A may be a particle in which a plurality of particles are aggregated. Examples of the shape of the particle A include a block shape, a scale shape, a spherical shape, and a fibrous shape. Of these, spherical or lump shape is preferable.
  • the particles A may be secondary particles.
  • the substance containing Si element include an alloy of Si element and alkaline earth metal; an alloy of Si and transition metal; an alloy of Si and metalloid; Si, Be, Ag, Al, Au, Cd. , Ga, In, Sb or Zn solid solution alloy or eutectic alloy; CaSi, CaSi 2 , Mg 2 Si, BaSi 2 , Cu 5 Si, FeSi, FeSi 2 , CoSi 2 , Ni 2 Si, NiSi 2 , MnSi, MnSi 2, MoSi 2, CrSi 2, Cr 3 Si, TiSi 2, Ti5Si 3, NbSi 2, NdSi 2, CeSi 2, WSi 2, W 5 Si 3, TaSi 2, Ta 5 Si 3, PtSi, V 3 Silicides such as Si, VSi 2 , PdSi, RuSi, RhSi; SiO 2 , SiC, Si 3 N 4 and the like can be mentioned.
  • Examples of the substance containing Sn element include tin alone, tin alloy, tin oxide, tin sulfide, tin halide, and stannate.
  • Specific examples of the substance containing the Sn element include an alloy of Sn and Zn, an alloy of Sn and Cd, an alloy of Sn and In, an alloy of Sn and Pb; SnO, SnO 2 , Mb 4 SnO 4 (Mb Represents a metal element other than Sn.)
  • Tin tin sulfide such as SnS, SnS 2 , Mb 2 SnS 3 ; SnX 2 , SnX 4 , MbSnX 4 (Mb represents a metal element other than Sn.
  • X Tin halides such as MgSn, Mg 2 Sn, FeSn, FeSn 2 , MoSn, and MoSn 2 .
  • the particle A has a 90% particle diameter (D 90 ) in a volume-based cumulative particle size distribution measured by a laser diffraction particle size distribution analyzer, preferably 500 nm or less, more preferably 450 nm or less. In the measurement of the particle size distribution, the particle size of secondary particles is also included.
  • the particles A preferably have a particle size distribution that does not substantially contain particles having a size of 1 ⁇ m or more. The larger the particle size, the more easily the particles A are crushed due to contraction and expansion during charge / discharge, and an increase in internal resistance and a decrease in charge / discharge cycle characteristics are likely to occur.
  • the particle A has a 10% particle diameter (D 10 ) in a volume-based cumulative particle size distribution measured by a laser diffraction particle size distribution analyzer, preferably 80 nm or more, more preferably 100 nm or more.
  • the particle A has a 50% particle size (D 50 ) in a volume-based cumulative particle size distribution measured by a laser diffraction particle size distribution analyzer, preferably 100 to 400 nm, more preferably 200 to 300 nm.
  • pulverizer examples include a hammer mill, a jaw crusher, and a collision pulverizer.
  • classification can be performed by airflow classification and / or sieving.
  • airflow classifier examples include a turbo cryfire and a turboplex.
  • the negative electrode material preferably further includes carbon particles C containing a graphite material in addition to the particles A described above.
  • the carbon particles C are contained in an amount of preferably 250 to 2000 parts by mass, more preferably 250 to 500 parts by mass with respect to 100 parts by mass of the particles A.
  • the carbon particles C have a 50% particle diameter (D 50 ) in a volume-based cumulative particle size distribution of preferably 2 to 40 ⁇ m, more preferably 2 to 15 ⁇ m.
  • D 50 particle diameter
  • the particle size of secondary particles is also included.
  • the volume-based cumulative particle size distribution can be measured by a laser diffraction particle size distribution measuring machine.
  • the carbon particles C preferably have a particle size distribution in which 90% or more of particles having a particle diameter in the range of 1 to 50 ⁇ m are present on a number basis, and 90% or more of particles having a particle diameter in the range of 5 to 50 ⁇ m on the number basis It is preferable that the particle size distribution exists.
  • the carbon particles C have a 10% particle diameter (D 10 ) in a volume-based cumulative particle size distribution measured by a laser diffraction particle size distribution analyzer, preferably 1 ⁇ m or more, more preferably 2 ⁇ m or more.
  • the carbon particles C may be particles composed only of graphite material (that is, graphite particles), or particles composed of graphite particles and a carbonaceous layer existing on the surface thereof (that is, carbon-coated graphite particles).
  • carbon-coated graphite particles or particles obtained by attaching carbon fibers to graphite particles may be used.
  • the graphite material examples include artificial graphite, pyrolytic graphite, expanded graphite, natural graphite, scaly graphite, and scaly graphite. Of these, artificial graphite is preferred.
  • the carbonaceous layer on the surface of the carbon-coated graphite particles has a peak intensity (I D ) derived from an amorphous component in the range of 1300 to 1400 cm ⁇ 1 and a range of 1580 to 1620 cm ⁇ 1 as measured by Raman spectroscopy.
  • the ratio I D / I G (R value) with the peak intensity (I G ) derived from the graphite component is preferably 0.1 or more, more preferably 0.2 or more.
  • Carbon-coated graphite particles can be produced according to a known method.
  • the graphite particles are agitated while spraying an organic compound such as an isotropic pitch, an anisotropic pitch, a resin, a resin precursor, or a monomer to the finely divided graphite particles.
  • the graphite particles and an organic compound such as pitch or phenol resin are mixed and mechanochemical treatment is performed using a device such as a hybridizer.
  • the adhesion amount of the organic compound is preferably 0.05 to 10 parts by mass, more preferably 0.1 to 10 parts by mass with respect to 100 parts by mass of the graphite particles.
  • the graphite particles to which the organic compound is adhered are preferably heat-treated at 200 ° C. or higher and 2000 ° C. or lower, more preferably 500 ° C. or higher and 1500 ° C. or lower. Carbon-coated graphite particles are obtained by this heat treatment.
  • the carbon fiber examples include vapor grown carbon fiber, petroleum pitch-based carbon fiber, coal pitch-based carbon fiber, and PAN-based carbon fiber. Of these, vapor grown carbon fiber is preferred.
  • the method for binding (adhering) the carbon fibers to the surface of the graphite particles or carbon-coated graphite particles For example, by mixing carbon fiber with an organic compound, attaching it to graphite particles or carbon-coated graphite particles, and then performing a heat treatment, the carbon fiber can be bound to the carbonaceous layer in the process of forming the carbonaceous layer. it can.
  • the amount of the carbon fiber is preferably 0.1 to 20 parts by mass, more preferably 0.1 to 15 parts by mass with respect to 100 parts by mass of the graphite particles.
  • the binder used in the slurry according to one embodiment of the present invention is ethylene containing, as essential components, a styrene, an ethylenically unsaturated carboxylic acid ester, an ethylenically unsaturated carboxylic acid, and a crosslinking agent having at least one ethylenically unsaturated group.
  • the binder is contained in an amount of preferably 1 to 100 parts by weight, more preferably 1 to 20 parts by weight, based on 100 parts by weight of the negative electrode material.
  • the reason why styrene is an essential component in the polymer B is to develop binding properties between the negative electrode materials.
  • the amount of styrene used is preferably 30 to 70% by mass, more preferably 40 to 60% by mass, based on the total ethylenically unsaturated monomer.
  • the glass transition temperature (Tg) of the polymer B falls within an appropriate range, and cracking is unlikely to occur in the negative electrode obtained from application of the slurry for negative electrode.
  • the total ethylenically unsaturated monomer does not include a surfactant having an ethylenically unsaturated group described later.
  • the ethylenically unsaturated carboxylic acid ester used as the raw material of the polymer B preferably contains an ethylenically unsaturated carboxylic acid ester having a polar group such as a hydroxy group or a glycidyl group.
  • a polar group such as a hydroxy group or a glycidyl group.
  • Specific examples include 2-hydroxyalkyl (meth) acrylate such as 2-hydroxyethyl (meth) acrylate and 2-hydroxypropyl (meth) acrylate, glycidyl acrylate, and the like. Of these, 2-hydroxyethyl (meth) acrylate is preferred.
  • the amount of the ethylenically unsaturated carboxylic acid ester having a polar group is preferably 0.1 to 10% by mass, preferably 0.5 to 5% by mass, based on the total ethylenically unsaturated monomers. It is.
  • the ethylenically unsaturated carboxylic acid having a polar group in an amount of 0.1% by mass or more, the polymerization stability or mechanical stability is improved, and the swelling resistance of the dry film against the electrolytic solution is improved.
  • the content is 10% by mass or less, the binding property between the negative electrode materials and between the negative electrode material and the current collector tends to be improved.
  • the ethylenically unsaturated carboxylic acid ester may include those other than the above (referred to as other ethylenically unsaturated carboxylic acid ester).
  • n-butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, lauryl (meth) acrylate, and isobornyl (meth) acrylate are preferred from the viewpoint of ease of emulsion polymerization and durability.
  • the amount of other ethylenically unsaturated carboxylic acid ester used is preferably 25 to 85% by mass, more preferably 30 to 80% by mass, based on the total ethylenically unsaturated monomer.
  • amount of the ethylenically unsaturated carboxylic acid ester used is 25% by mass or more, flexibility and heat resistance of the obtained negative electrode tend to be improved, and when it is 85% by mass or less, the negative electrode materials and the negative electrode material and the current collector are collected. There is a tendency to improve the binding with the body.
  • ethylenically unsaturated carboxylic acid Specific examples of the ethylenically unsaturated carboxylic acid include unsaturated monocarboxylic acids such as acrylic acid, methacrylic acid, and crotonic acid, unsaturated dicarboxylic acids such as maleic acid, fumaric acid, and itaconic acid, or unsaturated dicarboxylic acids thereof. Of these, and among them, acrylic acid and itaconic acid are preferable. These ethylenically unsaturated carboxylic acids may be used individually by 1 type, and may be used in combination of 2 or more type.
  • the amount of the ethylenically unsaturated carboxylic acid used is such that the acid value of the polymer B is preferably 6 to 100, more preferably 6 to 50.
  • the acid value is 6 or more, emulsion polymerization stability or mechanical stability is improved, and the heat resistance of the obtained negative electrode tends to be improved. Further, lithium ion, which is a negative electrode material, is occluded / released. Affinity and binding force with particles A other than carbon containing possible elements are improved.
  • the acid value is 100 or less, particularly when a material containing carbon particles C is used as the negative electrode material, the binding properties between the negative electrode materials and between the negative electrode material and the current collector tend to be improved.
  • the acid value is the number of mg of potassium hydroxide necessary to neutralize the carboxylic acid present in 1 g of resin. The acid value is measured according to JIS K5601-2-1 and can be obtained by the following formula (1).
  • Acid value (valence of carboxylic acid) ⁇ (mass% of ethylenically unsaturated carboxylic acid) ⁇ (molecular weight of ethylenically unsaturated carboxylic acid) ⁇ 56.1 ⁇ 1000 (1)
  • the amount of the ethylenically unsaturated carboxylic acid that provides the desired acid value varies depending on the type and ratio of the ethylenically unsaturated monomer used in the production of the polymer B.
  • the amount is preferably 1 to 10% by mass, more preferably 1 to 5% by mass based on the body.
  • Cross-linking agent Furthermore, in order to further improve the swelling resistance of the obtained lithium ion battery negative electrode with respect to the electrolyte solvent, a cross-linking agent having at least one ethylenically unsaturated bond is used in the production of the polymer B.
  • the cross-linking agent may be one having a group that reacts with a carboxyl group or one having two or more ethylenically unsaturated groups.
  • crosslinking agent monomers having two or more ethylenically unsaturated groups such as divinylbenzene, ethylene glycol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, triallyl cyanurate, vinyltrimethoxysilane
  • examples thereof include silane coupling agents having an ethylenically unsaturated group such as vinyltriethoxysilane, ⁇ -methacryloxypropyltrimethoxysilane, and ⁇ -methacryloxypropyltriethoxysilane.
  • divinylbenzene is preferable.
  • These crosslinking agents may be used alone or in combination of two or more.
  • the amount of the crosslinking agent used is preferably 0.1 to 5% by mass and more preferably 0.1 to 3% by mass with respect to the total ethylenically unsaturated monomer.
  • the amount of the crosslinking agent used is 0.1% by mass or more, the swelling resistance of the dry film to the electrolytic solution tends to be improved, and when it is 5% by mass or less, the emulsion polymerization stability is improved. The adhesion between the negative electrode material and the current collector tends to be improved.
  • a compound having at least one polymerizable ethylenically unsaturated group may be used as the ethylenically unsaturated monomer as long as the object of the present invention is not impaired.
  • the compound having a polar group such as an amide group and a nitrile group include (meth) acrylamide, N-methylol (meth) acrylamide, (meth) acrylonitrile, N-vinylpyrrolidone and the like. Vinyl acetate and vinyl propionate can also be used.
  • a compound having a mercapto group, thioglycolic acid and its ester, ⁇ -mercaptopropionic acid and its ester may be used for adjusting the molecular weight.
  • the Tg of the polymer B is preferably 30 ° C. or lower.
  • Tg is 30 ° C. or lower, cracks occur in the negative electrode obtained from the application of the slurry for negative electrode, which is not preferable.
  • the above polymer B has a dry film swelling ratio of preferably 300% or less, more preferably 5% to 200%, with respect to a solvent of propylene carbonate / diethyl carbonate electrolyte at 60 ° C. It is preferable that the swelling resistance of the dry film with respect to the electrolytic solution at 60 ° C. is 300% or less because charge / discharge high temperature cycle characteristics at high temperatures are lowered.
  • the polymer B used for the slurry is obtained by polymerizing the above ethylenically unsaturated monomer. Usually, the polymerization is carried out by emulsion polymerization using water as a dispersion medium in the presence of a surfactant to obtain an aqueous emulsion containing the polymer B.
  • the reactive surfactant used in the polymerization is not particularly limited as long as it is a normal anionic surfactant or nonionic surfactant.
  • the anionic surfactant include alkyl benzene sulfonate, alkyl sulfate ester salt, polyoxyethylene alkyl ether sulfate ester salt, fatty acid salt, and the like.
  • Nonionic surfactants include polyoxyethylene alkyl ether, polyoxyethylene alkyl ether, Examples thereof include oxyethylene alkyl phenyl ether, polyoxyethylene polycyclic finyl ether, polyoxyalkylene alkyl ether, sorbitan fatty acid ester, polyoxyethylene sorbitan fatty acid ester and the like. These may be used individually by 1 type and may be used in combination of 2 or more type.
  • Preferred surfactants include those having an ethylenically unsaturated group, and more preferred are those represented by the following formulas (2) to (5).
  • R is an alkyl group, and n is an integer of 10 to 40
  • n is an integer of 10 to 12
  • m is an integer of 10 to 40
  • R is an alkyl group, M is NH 4 or Na
  • the amount of the surfactant used is not particularly limited.
  • a surfactant having an ethylenically unsaturated group it is preferably 0.3 to 3% by mass based on the total ethylenically unsaturated monomer.
  • the amount of the surfactant used is 0.3% by mass or more, the polymerization stability is improved, and since the particle system of the obtained aqueous emulsion is small, the resin emulsion does not easily precipitate.
  • the amount of the surfactant used is 3% by mass or less, the adhesion between the negative electrode material and the current collector is improved, which is preferable.
  • the radical polymerization initiator used in the polymerization may be a known and conventional one, and examples thereof include persulfate and peroxide.
  • examples of the persulfate include ammonium persulfate and potassium persulfate
  • examples of the peroxide include hydrogen peroxide and organic peroxides such as t-butyl hydroperoxide and cumene hydroperoxide.
  • these polymerization initiators may be used in combination with a reducing agent such as sodium bisulfite, Rongalite, and ascorbic acid for redox polymerization.
  • the polymerization method As the polymerization method, a polymerization method charged in a batch, a polymerization method while continuously supplying each component, and the like are applied.
  • the polymerization is usually carried out at a temperature of 30 to 90 ° C. with stirring.
  • the pH of the aqueous emulsion is adjusted to improve the polymerization stability, mechanical stability, and chemical stability during polymerization. be able to.
  • ammonia triethylamine, ethanolamine, caustic soda and the like can be used. These may be used individually by 1 type and may be used in combination of 2 or more type.
  • the binder may contain components other than the polymer B described above.
  • other components include carboxymethylcellulose, methylcellulose, hydroxymethylcellulose, ethylcellulose, polyvinyl alcohol, polyacrylic acid (salt), oxidized starch, phosphorylated starch, and casein.
  • the amount of these other binder components used is preferably 5 to 200 parts by weight, more preferably 50 to 150 parts by weight, based on 100 parts by weight of the polymer B.
  • the slurry contains a dispersion medium containing water.
  • the water contained in the dispersion medium is usually derived from the aqueous emulsion containing the above-mentioned polymer B, but is not limited thereto, and the amount can be appropriately adjusted depending on the viscosity of the slurry.
  • the dispersion medium may contain an organic solvent miscible with water as long as the object of the present invention is not impaired. Examples thereof include N, N-dimethylformamide, N, N-dimethylacetamide, N-methylpyrrolidone, methanol, isopropyl alcohol, butanol, acetone, 2-butanone and cyclohexanone. When these organic solvents are used, the amount used is preferably 1 to 50% by mass, more preferably 1 to 20% by mass in the dispersion medium, and may not be used.
  • the slurry may contain a conductive aid.
  • the conductive auxiliary agent is not particularly limited as long as it has a function of imparting conductivity and electrode stability to the negative electrode (buffering action against volume change in insertion / extraction of lithium ions).
  • vapor grown carbon fiber for example, “VGCF” (registered trademark) manufactured by Showa Denko KK
  • conductive carbon for example, “Denka Black” (registered trademark) manufactured by Denki Kagaku Kogyo Co., Ltd., “Super C65” manufactured by TIMCAL, “Super C45” TIMCAL And “KS6L” manufactured by TIMCAL).
  • the amount of the conductive auxiliary is preferably 10 to 150 parts by mass, more preferably 50 to 100 parts by mass with respect to 100 parts by mass of the negative electrode material.
  • the slurry for a lithium ion battery electrode according to an embodiment of the present invention is obtained by mixing the above-described components.
  • the well-known method used for manufacture of a lithium ion battery can be used.
  • a method of adding a negative electrode material and a conductive additive to the above-described aqueous emulsion containing the polymer B and further dispersing, dissolving, or kneading can be mentioned.
  • a negative electrode for a lithium ion battery includes a current collector and a negative electrode mixture layer.
  • the thickness of the negative electrode for a lithium ion battery is usually 50 to 200 ⁇ m.
  • the current collector for example, a metal foil made of nickel, copper, aluminum, or an alloy thereof can be used.
  • the metal foil may be a normal foil without holes, or a foil with holes such as a punching metal foil, a metal mesh, or a porous foil.
  • a known conductive layer for example, Japanese Patent Application Laid-Open No. 2006-32902, Japanese Patent Application Laid-Open No. 2008-60060, Japanese Patent Application Laid-Open No.
  • the negative electrode mixture layer includes the above-described negative electrode material, a binder, and, if necessary, a conductive additive.
  • the composition ratio is preferably 1 to 100 parts by weight, more preferably 1 to 20 parts by weight, and preferably 10 to 150 parts by weight, more preferably 50 to 100 parts by weight of the conductive auxiliary, with respect to 100 parts by weight of the negative electrode material. Part by mass.
  • the negative electrode for a lithium ion battery has other layers such as a protective layer (see, for example, JP-A-2008-226666, JP-A-2009-181756, and JP-A-2010-244818) as necessary. You may do it.
  • the negative electrode for a lithium ion battery can be obtained, for example, by applying the above slurry to a current collector and drying it.
  • the method for applying the slurry is not particularly limited.
  • the thickness of the negative electrode for a lithium ion battery described above can be adjusted by the amount of slurry applied.
  • after drying the slurry for negative electrodes it can also adjust by carrying out pressure molding.
  • the pressure molding method include molding methods such as roll pressing and press pressing.
  • the pressure during pressure molding is preferably about 100 MPa to about 300 MPa (about 1 to 3 ton / cm 2 ).
  • a lithium ion battery according to an embodiment of the present invention has at least one selected from the group consisting of a non-aqueous electrolyte and a non-aqueous polymer electrolyte, a positive electrode, and the above-described negative electrode.
  • a sheet conventionally used for lithium ion batteries specifically, a sheet containing a positive electrode active material can be used.
  • the positive electrode active material include LiNiO 2 , LiCoO 2 , LiMn 2 O 4 , LiNi 0.34 Mn 0.33 Co 0.33 O 2 , and LiFePO 4 .
  • the non-aqueous electrolyte and non-aqueous polymer electrolyte used for the lithium ion battery are not particularly limited.
  • a lithium salt such as LiClO 4 , LiPF 6 , LiAsF 6 , LiBF 4 , LiSO 3 CF 3 , CH 3 SO 3 Li, CF 3 SO 3 Li, ethylene carbonate, diethyl carbonate, dimethyl carbonate, ethyl methyl carbonate, propylene Organic electrolytes dissolved in non-aqueous solvents such as carbonate, butylene carbonate, acetonitrile, propyronitrile, dimethoxyethane, tetrahydrofuran, and ⁇ -butyrolactone; polyethylene oxide, polyacrylonitrile, polyvinylidene fluoride, polymethyl methacrylate, etc.
  • examples thereof include a gel polymer electrolyte and a solid polymer electrolyte containing a polymer having an ethylene oxide bond.
  • a small amount of a substance that causes a decomposition reaction when the lithium ion battery is initially charged may be added to the electrolytic solution.
  • the substance include vinylene carbonate, biphenyl, propane sultone, and the like.
  • the addition amount is preferably 0.01 to 5% by mass.
  • a lithium ion battery can be provided with a separator between the positive electrode and the negative electrode.
  • the separator include non-woven fabrics, cloths, microporous films, or a combination thereof, mainly composed of polyolefins such as polyethylene and polypropylene.
  • a known inorganic particle layer (see, for example, Japanese Patent Application Laid-Open No. 2001-319634, International Publication Pamphlet WO 2007/066768, Japanese Patent Application Laid-Open No. 2008-126996, Japanese Patent Application Laid-Open No. 2008-123988) is provided on the surface of the separator. It may be.
  • FIG. 2 shows a lithium ion battery according to an embodiment of the present invention.
  • a lithium ion battery 10 shown here is a separator that separates a negative electrode 1, a positive electrode 2 opposite to the negative electrode 1, and the negative electrode 1 and the positive electrode 2. 3 and a container 4 for housing them.
  • the negative electrode 1 includes a current collector 5 and a negative electrode mixture layer 6 provided on the surface of the current collector 5.
  • Reference numeral 7 denotes an electrolyte injected into the container 4.
  • the container 4 includes a main body 4a that houses the negative electrode 1, the positive electrode 2, and the separator 3, and a lid 4b that closes the main body 4a.
  • aqueous emulsion had a non-volatile content of 45.5%, a viscosity of 3000 mPa ⁇ s, a pH of 6.5, and the acid value of the polymer B was 18.95.
  • Si fine particles Alfa Aesar, CAS7440-21-3, product number 44384, primary particle size of 50 nm or less
  • carbon particles C carbon-coated graphite particles were prepared by the following procedure. Petroleum coke was pulverized to an average particle size of 5 ⁇ m. This was heat-treated at 3000 ° C. in an Atchison furnace to obtain graphite particles. Next, petroleum pitch was mixed with the graphite particles at a mass ratio of 1%, and the petroleum pitch was adhered to the surface of the graphite particles. Then, it carbonized at 1100 degreeC by inert atmosphere.
  • BET specific surface area is 2.6 m 2 / g
  • d002 is 0.3361 nm
  • LC is 59 nm
  • 10% particle diameter (D10) is 2.3 ⁇ m
  • 50% particle diameter (D50) is 5.7 ⁇ m
  • Carbon-coated graphite particles having a 90% particle diameter (D90) of 11.8 ⁇ m and I D / I G (R value) of 0.77 were obtained.
  • 0.375 g of Si fine particles and 1.125 g of carbon-coated graphite particles C were taken and mixed in a mortar to obtain a negative electrode material in which Si fine particles and graphite particles were combined.
  • a binder mixture was prepared by adding carboxymethyl cellulose (manufactured by Daicel, product number: 1380) to the aqueous emulsion so that the solid mass ratio was 1: 1, and mixing them.
  • TIMCAL carbon black (SUPER C45) was prepared as a conductive aid.
  • the obtained slurry for a lithium ion battery negative electrode was applied on a copper foil such that the negative electrode mixture layer had a thickness of 120 ⁇ m. This was dried at 70 ° C. for 3 hours. A sheet piece having a diameter of 16 mm was punched out from the obtained sheet, and pressed at 1.5 ton / cm 2 with a POWER SAMPLE HYDRAULIC PRESS / BRE-3 manufactured by Maekawa Tester, Ltd., to obtain a negative electrode. There was no transfer on the negative electrode after pressing.
  • a 2320 type coin cell (diameter 23 mm, thickness 2.0 mm) was prepared. A foil piece having a diameter of 20 mm was punched from a lithium foil having a thickness of 0.1 mm. This was used as a positive electrode. The positive electrode was lightly pressure-bonded to a SUS spacer with a punch. This was put in a coin cell cap. Next, an electrolytic solution was injected into the coin cell.
  • the electrolytic solution was obtained by dissolving electrolyte LiPF 6 at a concentration of 1 mol / L in a solvent in which ethylene carbonate, methyl ethyl carbonate, and diethyl carbonate were mixed at a volume ratio of 3: 5: 2. It is.
  • aqueous emulsion In the synthesis of the aqueous emulsion, the same operation as in the synthesis of the aqueous emulsion described in Example 1 was performed except that 250 parts of styrene and 220 parts of 2-ethylhexyl acrylate were changed to 320 parts of styrene and 150 parts of 2-ethylhexyl acrylate. It was.
  • the obtained aqueous emulsion had a nonvolatile content of 44.9%, a viscosity of 2900 mPa ⁇ s, a pH of 6.5, and the acid value of the polymer B was 18.95.
  • the preparation of the Si-graphite composite negative electrode material, the production of the negative electrode, the production of the evaluation battery, and various evaluations were performed in the same manner as in Example 1. The results are shown in Table 1.
  • Example 1 A negative electrode was produced in the same manner as in Example 1 except that the aqueous emulsion was changed to SBR (manufactured by Zeon Corporation, product number: BM400B) in Example 1, and an evaluation battery was produced and a charge / discharge test was performed. The results are shown in Table 1 and FIG. After pressing, the negative electrode sheet adhered to the press plate, and the negative electrode mixture layer was slightly transferred.
  • SBR manufactured by Zeon Corporation, product number: BM400B
  • the binders in Examples 1 and 2 also show good binding properties with respect to the alloy-based negative electrode.
  • the evaluation batteries using the binders in Example 1 and Example 2 have high initial charge / discharge amounts and high initial efficiency, and excellent cycle characteristics at the 50th cycle.

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Abstract

A slurry which contains: a negative electrode material for lithium ion batteries, which contains, as an active material, particles (A) that contain at least one element selected from the group consisting of Si, Sn, Ge and In; a binder which contains a polymer (B) that is obtained by polymerizing an ethylenically unsaturated monomer in the presence of a reactive surfactant, said ethylenically unsaturated monomer containing styrene, an ethylenically unsaturated carboxylic acid ester, an ethylenically unsaturated carboxylic acid and a crosslinking agent as essential ingredients; and a dispersion medium which contains water.

Description

スラリー及びリチウムイオン電池用負極Slurry and negative electrode for lithium ion battery
　本発明は、スラリーに関する。より詳細には、本発明は、充放電容量が大きく、充放電サイクル特性が良好なリチウムイオン電池を得ることができるスラリー、該スラリーを塗布して成る負極及び該負極を有するリチウムイオン電池に関する。
　本願は、２０１２年８月８日に日本に出願された特願２０１２－１７６４０１号に基づき優先権を主張し、その内容をここに援用する。 The present invention relates to a slurry. More specifically, the present invention relates to a slurry capable of obtaining a lithium ion battery having a large charge / discharge capacity and good charge / discharge cycle characteristics, a negative electrode formed by applying the slurry, and a lithium ion battery having the negative electrode.
This application claims priority based on Japanese Patent Application No. 2012-176401 for which it applied to Japan on August 8, 2012, and uses the content here.
　電子部品の省電力化を上回る速さで携帯電子機器の多機能化が進んでいるために、携帯電子機器の消費電力が増加している。そのため、携帯電子機器の主電源であるリチウムイオン電池の高容量化及び小型化がいままで以上に強く求められている。また、電動自動車の需要が伸び、それに使われるリチウムイオン電池にも高容量化が強く求められている。 The power consumption of portable electronic devices is increasing because the multifunction of portable electronic devices is progressing faster than the power saving of electronic components. Therefore, higher capacity and smaller size of the lithium ion battery, which is the main power source of portable electronic devices, are more strongly demanded than ever. In addition, the demand for electric vehicles is increasing, and the lithium-ion batteries used there are also strongly required to have a high capacity.
　リチウムイオン電池の高容量化を図るために、理論容量の大きいＳｉや、Ｓｎなどの金属元素を含む粒子を負極材料に用いることが検討されている。例えば、Ｓｉを含む粒子を負極材料に用いた場合のリチウムイオン電池の理論容量は４２００ｍＡｈ／ｇである。金属リチウムを用いた場合のリチウム電池の理論容量は３９００ｍＡｈ／ｇであるので、Ｓｉなどを負極材料に用いることができれば、金属リチウム電池よりも小型で高容量なリチウムイオン電池が得られると期待される。ところが、Ｓｉなどの負極材料はリチウムイオンの挿入・脱離（吸蔵・放出）に伴う膨張率及び収縮率が大きい。そのために粒子間に隙間が生じて期待したほどの容量が得られない。また、大きな膨張と収縮の繰り返しにより粒子が砕けて微粉化するために電気的な接触が分断されて内部抵抗が増加するので、得られるリチウムイオン電池は充放電サイクル寿命が短い。 In order to increase the capacity of lithium ion batteries, it has been studied to use particles containing metal elements such as Si and Sn having a large theoretical capacity as a negative electrode material. For example, the theoretical capacity of a lithium ion battery when Si-containing particles are used as the negative electrode material is 4200 mAh / g. Since the theoretical capacity of a lithium battery using metal lithium is 3900 mAh / g, if Si or the like can be used as a negative electrode material, it is expected that a lithium ion battery having a smaller size and higher capacity than a metal lithium battery can be obtained. The However, a negative electrode material such as Si has a large expansion coefficient and contraction coefficient associated with insertion / extraction (occlusion / release) of lithium ions. For this reason, gaps are generated between the particles, and the expected capacity cannot be obtained. Further, since the particles are crushed and pulverized by repeated large expansion and contraction, the electrical contact is interrupted and the internal resistance is increased, so that the obtained lithium ion battery has a short charge / discharge cycle life.
　従来、活物質を集電体に結着させるバインダーとして、有機溶剤のＮ－メチル－ピロリドン（ＮＭＰ）を溶媒として、電解液に対する樹脂自体の耐膨潤性が高く、またスラリーの作製が容易なポリフッ化ビニリデン（ＰＶＤＦ）が用いられてきた。しかしながら、この有機溶剤系バインダーは活物質同士及び活物質と集電体との結着性が低く、実効的な結着力を得るためには大量のバインダーを必要とし、結果としてリチウムイオン電池の容量及びエネルギー密度が低下する欠点がある。また有機溶剤系バインダーは、その溶媒に高価な有機溶剤であるＮＭＰを使用しているため、最終製品の価格が高価になるという欠点がある。 Conventionally, the organic solvent N-methyl-pyrrolidone (NMP) is used as a binder for binding the active material to the current collector, and the resin itself has high swelling resistance to the electrolyte solution. Vinylidene chloride (PVDF) has been used. However, this organic solvent-based binder has a low binding property between active materials and between an active material and a current collector, and a large amount of binder is required to obtain an effective binding force, resulting in the capacity of a lithium ion battery. In addition, there is a disadvantage that the energy density is lowered. In addition, the organic solvent-based binder uses NMP, which is an expensive organic solvent, in the solvent, so that the price of the final product is high.
　これらの問題を解決する方法として、増粘剤としてカルボキシメチルセルロース（ＣＭＣ）を併用したスチレン－ブタジエンゴム（ＳＢＲ）系の水分散体が提案されている（例えば、特許文献１～３参照）。このＳＢＲ系分散剤は水分散体であるために安価であり、かつ活物質同士及び活物質と集電体との結着性が良好なことから、水系のリチウムイオン電池用バインダーとして幅広い用途に使用されてきた。大容量が期待される、Ｓｉ等を含む合金負極に対するバインダーとしても、ＰＶＤＦを用いた場合に比べて水系バインダーを用いたものは格段にサイクル特性が向上することが知られている（例えば、非特許文献１参照）。 As a method for solving these problems, a styrene-butadiene rubber (SBR) -based aqueous dispersion using carboxymethyl cellulose (CMC) as a thickener has been proposed (see, for example, Patent Documents 1 to 3). Since this SBR dispersant is an aqueous dispersion, it is inexpensive and has good binding properties between active materials and between an active material and a current collector. Therefore, it is widely used as a binder for aqueous lithium ion batteries. Have been used. As a binder for an anode of an alloy containing Si or the like, which is expected to have a large capacity, it is known that the cycle characteristics of a binder using an aqueous binder are remarkably improved as compared with the case of using PVDF (for example, non-binding). Patent Document 1).
特開平５－７４４６１号公報JP-A-5-74461 特開平６－１５０９０６号公報JP-A-6-150906 特開平８－２５０１２３号公報JP-A-8-250123
　従来の水系バインダーは機械的安定性が低く、また電解液溶媒に対する膨潤性が低いという問題があった。また、水系バインダーでは活物質同士が凝集しやすく、均一なスラリーを作ることが難しいという欠点があった。従って、これまで検討されてきた水系バインダーでは、充放電容量が大きく、充放電効率が高く、充放電サイクル特性がよいというリチウムイオン電池を製造することはできなかった。 Conventional water-based binders have problems of low mechanical stability and low swellability with respect to the electrolyte solvent. Further, the aqueous binder has a drawback that the active materials are easily aggregated and it is difficult to form a uniform slurry. Therefore, the water-based binders that have been studied so far have not been able to produce a lithium ion battery having a large charge / discharge capacity, high charge / discharge efficiency, and good charge / discharge cycle characteristics.
　本発明の目的は、水分散系バインダーを用いて、活物質同士及び活物質と集電体との結着性が良好で、充放電容量が大きく、充放電効率が高く、充放電サイクル特性を向上させるリチウムイオン電池を得ることができる、合金系のスラリー、該スラリーを用いて得られた負極、及び該負極を有するリチウムイオン電池を提供することである。 The object of the present invention is to use a water-dispersed binder, have good binding properties between active materials and between an active material and a current collector, have a large charge / discharge capacity, high charge / discharge efficiency, and charge / discharge cycle characteristics. It is an object to provide an alloy-based slurry, a negative electrode obtained using the slurry, and a lithium ion battery having the negative electrode, which can provide a lithium ion battery to be improved.
　本発明は、以下の［１］～［１０］に関する。
［１］　Ｓｉ、Ｓｎ、Ｇｅ及びＩｎからなる群から選ばれるうちの少なくとも一つの元素を含む粒子Ａを活物質として含むリチウムイオン電池用負極材、
　スチレン、エチレン性不飽和カルボン酸エステル、エチレン性不飽和カルボン酸、及び少なくとも一つのエチレン性不飽和基を有する架橋剤、を必須成分として含有するエチレン性不飽和単量体を重合して得られる重合体Ｂを含むバインダー、及び、
　水を含む分散媒、を含むスラリー。
［２］　前記重合体Ｂの酸価が６～１００であることを特徴とする上記［１］に記載のスラリー。
［３］　前記エチレン性不飽和単量体中、スチレンの含有量が３０～７０質量％である、上記［１］及び［２］のいずれか１項に記載のリチウムイオン電池用電極スラリー。
［４］　前記エチレン性不飽和単量体中、前記架橋剤の含有量が０．１～５質量％である、上記［１］乃至［３］のいずれか１項に記載のスラリー。
［５］　前記リチウムイオン電池用負極材が、炭素粒子Ｃをさらに含む、上記［１］乃至［４］のいずれか１項に記載のスラリー。
［６］　前記粒子Ａの１００質量部に対し、前記炭素粒子Ｃを２５０～２０００質量部含む、上記［６］に記載のスラリー。
［７］　Ｓｉ、Ｓｎ、Ｇｅ及びＩｎからなる群から選ばれるうちの少なくとも一つの元素を含む粒子Ａを活物質として含むリチウムイオン電池用負極材、及び、
　スチレン、エチレン性不飽和カルボン酸エステル、エチレン性不飽和カルボン酸、及び少なくとも一つのエチレン性不飽和基を有する架橋剤、を必須成分として含有するエチレン性不飽和単量体を重合して得られる重合体Ｂを含むバインダー、を含むリチウムイオン電池用負極。
［８］　上記［７］に記載のリチウムイオン電池用負極を用いて得られるリチウムイオン電池。
［９］　Ｓｉ、Ｓｎ、Ｇｅ及びＩｎからなる群から選ばれるうちの少なくとも一つの元素を含む粒子Ａを活物質として含むリチウムイオン電池用負極材と、
　スチレン、エチレン性不飽和カルボン酸エステル、エチレン性不飽和カルボン酸、及び少なくとも一つのエチレン性不飽和基を有する架橋剤、を必須成分として含有するエチレン性不飽和単量体を界面活性剤の存在下、重合して得られる重合体Ｂを含む水性エマルジョンとを混合する工程を含む、スラリーの製造方法。
［１０］　集電体上に、上記［１］乃至［６］に記載のスラリーを塗布する工程を含むリチウムイオン電池用負極の製造方法。 The present invention relates to the following [1] to [10].
[1] A negative electrode material for a lithium ion battery containing, as an active material, particles A containing at least one element selected from the group consisting of Si, Sn, Ge, and In,
Obtained by polymerizing an ethylenically unsaturated monomer containing styrene, an ethylenically unsaturated carboxylic acid ester, an ethylenically unsaturated carboxylic acid, and a crosslinking agent having at least one ethylenically unsaturated group as essential components A binder comprising polymer B, and
A slurry containing a dispersion medium containing water.
[2] The slurry according to [1] above, wherein the acid value of the polymer B is 6 to 100.
[3] The electrode slurry for a lithium ion battery according to any one of [1] and [2] above, wherein the content of styrene in the ethylenically unsaturated monomer is 30 to 70% by mass.
[4] The slurry according to any one of [1] to [3], wherein the content of the crosslinking agent in the ethylenically unsaturated monomer is 0.1 to 5% by mass.
[5] The slurry according to any one of [1] to [4], wherein the negative electrode material for a lithium ion battery further includes carbon particles C.
[6] The slurry according to [6], wherein 250 to 2000 parts by mass of the carbon particles C are included with respect to 100 parts by mass of the particles A.
[7] A negative electrode material for a lithium ion battery containing, as an active material, particles A containing at least one element selected from the group consisting of Si, Sn, Ge, and In;
Obtained by polymerizing an ethylenically unsaturated monomer containing styrene, an ethylenically unsaturated carboxylic acid ester, an ethylenically unsaturated carboxylic acid, and a crosslinking agent having at least one ethylenically unsaturated group as essential components A negative electrode for a lithium ion battery, comprising a binder containing the polymer B.
[8] A lithium ion battery obtained using the negative electrode for a lithium ion battery according to [7].
[9] A negative electrode material for a lithium ion battery containing, as an active material, particles A containing at least one element selected from the group consisting of Si, Sn, Ge, and In;
Presence of surfactant with ethylenically unsaturated monomer containing styrene, ethylenically unsaturated carboxylic acid ester, ethylenically unsaturated carboxylic acid, and crosslinking agent having at least one ethylenically unsaturated group as essential components The manufacturing method of a slurry including the process of mixing below with the aqueous emulsion containing the polymer B obtained by superposition | polymerization.
[10] A method for producing a negative electrode for a lithium ion battery, comprising a step of applying the slurry according to the above [1] to [6] on a current collector.
　本発明のスラリーを用いることによって、水分散系バインダーを用いて、活物質同士及び活物質と集電体との結着性が良好で充放電サイクル特性を向上させるリチウムイオン電池を得ることができる。また本発明のリチウムイオン電池負極用スラリーを用いて得られたリチウムイオン電池は、従来の水系バインダーを用いて作製したものに比べて充放電容量が大きく、充放電効率に優れる。 By using the slurry of the present invention, it is possible to obtain a lithium ion battery having good binding properties between the active materials and between the active material and the current collector and improving the charge / discharge cycle characteristics using the water dispersion binder. . Moreover, the lithium ion battery obtained using the slurry for lithium ion battery negative electrodes of this invention has a large charge / discharge capacity compared with what was produced using the conventional aqueous binder, and is excellent in charge / discharge efficiency.
実施例１及び比較例１におけるサイクル特性を示す図である。It is a figure which shows the cycle characteristics in Example 1 and Comparative Example 1. 本発明の一実施形態に係るリチウムイオン電池を示す模式図である。It is a schematic diagram which shows the lithium ion battery which concerns on one Embodiment of this invention.
［スラリー］＜負極材＞
　本発明の一実施形態に係るスラリーに用いる負極材は、Ｓｉ、Ｓｎ、Ｇｅ及びＩｎからなる群から選ばれるうちの少なくとも一つの元素を含む粒子Ａを活物質として含む。 [Slurry] <Negative electrode material>
The negative electrode material used for the slurry according to one embodiment of the present invention includes, as an active material, particles A containing at least one element selected from the group consisting of Si, Sn, Ge, and In.
（粒子Ａ）
　本発明の一実施形態に係る負極材の構成物質の一つである粒子Ａは、Ｓｉ、Ｓｎ、ＧｅおよびＩｎからなる群から選ばれるうちの少なくとも一つの元素を含む。これら元素のうち、好ましくはＳｉまたはＳｎである。粒子Ａはこれら元素の単体またはこれら元素を含む化合物からなるものであってもよいし、これら元素のうちの少なくとも２つを含む化合物、混合体、共融体または固溶体からなるものであってもよい。また粒子Ａは、複数の粒子が凝集したものであってもよい。粒子Ａの形状としては、塊状、鱗片状、球状、繊維状などが挙げられる。これらのうち、球状または塊状が好ましい。粒子Ａは二次粒子化していてもよい。 (Particle A)
The particle A which is one of the constituent materials of the negative electrode material according to one embodiment of the present invention contains at least one element selected from the group consisting of Si, Sn, Ge and In. Of these elements, Si or Sn is preferable. The particle A may be composed of a simple substance of these elements or a compound containing these elements, or may be composed of a compound, a mixture, a eutectic or a solid solution containing at least two of these elements. Good. The particle A may be a particle in which a plurality of particles are aggregated. Examples of the shape of the particle A include a block shape, a scale shape, a spherical shape, and a fibrous shape. Of these, spherical or lump shape is preferable. The particles A may be secondary particles.
　Ｓｉ元素を含む物質の具体例としては、Ｓｉ元素とアルカリ土類金属との合金；Ｓｉと遷移金属との合金；Ｓｉと半金属との合金；Ｓｉと、Ｂｅ、Ａｇ、Ａｌ、Ａｕ、Ｃｄ、Ｇａ、Ｉｎ、ＳｂまたはＺｎとの固溶性合金または共融性合金；ＣａＳｉ、ＣａＳｉ２、Ｍｇ２Ｓｉ、ＢａＳｉ２、Ｃｕ５Ｓｉ、ＦｅＳｉ、ＦｅＳｉ２、ＣｏＳｉ２、Ｎｉ２Ｓｉ、ＮｉＳｉ２、ＭｎＳｉ、ＭｎＳｉ２、ＭｏＳｉ２、ＣｒＳｉ２、Ｃｒ３Ｓｉ、ＴｉＳｉ２、Ｔｉ５Ｓｉ３、ＮｂＳｉ２、ＮｄＳｉ２、ＣｅＳｉ２、ＷＳｉ２、Ｗ５Ｓｉ３、ＴａＳｉ２、Ｔａ５Ｓｉ３、ＰｔＳｉ、Ｖ３Ｓｉ、ＶＳｉ２、ＰｄＳｉ、ＲｕＳｉ、ＲｈＳｉなどのケイ化物；ＳｉＯ２、ＳｉＣ、Ｓｉ３Ｎ４などが挙げられる。 Specific examples of the substance containing Si element include an alloy of Si element and alkaline earth metal; an alloy of Si and transition metal; an alloy of Si and metalloid; Si, Be, Ag, Al, Au, Cd. , Ga, In, Sb or Zn solid solution alloy or eutectic alloy; CaSi, CaSi 2 , Mg 2 Si, BaSi 2 , Cu 5 Si, FeSi, FeSi 2 , CoSi 2 , Ni 2 Si, NiSi 2 , MnSi, MnSi 2, MoSi 2, CrSi 2, Cr 3 Si, TiSi 2, Ti5Si 3, NbSi 2, NdSi 2, CeSi 2, WSi 2, W 5 Si 3, TaSi 2, Ta 5 Si 3, PtSi, V 3 Silicides such as Si, VSi 2 , PdSi, RuSi, RhSi; SiO 2 , SiC, Si 3 N 4 and the like can be mentioned.
　Ｓｎ元素を含む物質としては、錫単体、錫合金、酸化錫、硫化錫、ハロゲン化錫、錫化物などが挙げられる。Ｓｎ元素を含む物質の具体例としては、ＳｎとＺｎとの合金、ＳｎとＣｄとの合金、ＳｎとＩｎとの合金、ＳｎとＰｂとの合金；ＳｎＯ、ＳｎＯ２、Ｍｂ４ＳｎＯ４（ＭｂはＳｎ以外の金属元素を示す。）などの酸価錫；ＳｎＳ、ＳｎＳ２、Ｍｂ２ＳｎＳ３などの硫化錫；ＳｎＸ２、ＳｎＸ４、ＭｂＳｎＸ４（ＭｂはＳｎ以外の金属元素を示す。Ｘはハロゲン原子を示す。）などのハロゲン化錫；ＭｇＳｎ、Ｍｇ２Ｓｎ、ＦｅＳｎ、ＦｅＳｎ２、ＭｏＳｎ、ＭｏＳｎ２などの錫化物が挙げられる。 Examples of the substance containing Sn element include tin alone, tin alloy, tin oxide, tin sulfide, tin halide, and stannate. Specific examples of the substance containing the Sn element include an alloy of Sn and Zn, an alloy of Sn and Cd, an alloy of Sn and In, an alloy of Sn and Pb; SnO, SnO 2 , Mb 4 SnO 4 (Mb Represents a metal element other than Sn.) Tin tin sulfide such as SnS, SnS 2 , Mb 2 SnS 3 ; SnX 2 , SnX 4 , MbSnX 4 (Mb represents a metal element other than Sn. X Tin halides such as MgSn, Mg 2 Sn, FeSn, FeSn 2 , MoSn, and MoSn 2 .
　粒子Ａは、レーザー回折式粒度分布測定機によって測定される体積基準累積粒度分布における９０％粒子径（Ｄ９０）が、好ましくは５００ｎｍ以下、より好ましくは４５０ｎｍ以下である。なお、この粒度分布の測定においては二次粒子の粒径も含まれている。また、粒子Ａは、１μｍ以上の大きさの粒子を実質的に含まない粒度分布のものがよい。
　粒子Ａは、粒径が大きくなるほど、充放電時の収縮と膨張により砕けやすく、内部抵抗の増加及び充放電サイクル特性の低下を招きやすい。
　粒子Ａは、レーザー回折式粒度分布測定機によって測定される体積基準累積粒度分布における１０％粒子径（Ｄ１０）が、好ましくは８０ｎｍ以上、より好ましくは１００ｎｍ以上である。また、粒子Ａは、レーザー回折式粒度分布測定機によって測定される体積基準累積粒度分布における５０％粒子径（Ｄ５０）が、好ましくは１００～４００ｎｍ、より好ましくは２００～３００ｎｍである。 The particle A has a 90% particle diameter (D 90 ) in a volume-based cumulative particle size distribution measured by a laser diffraction particle size distribution analyzer, preferably 500 nm or less, more preferably 450 nm or less. In the measurement of the particle size distribution, the particle size of secondary particles is also included. The particles A preferably have a particle size distribution that does not substantially contain particles having a size of 1 μm or more.
The larger the particle size, the more easily the particles A are crushed due to contraction and expansion during charge / discharge, and an increase in internal resistance and a decrease in charge / discharge cycle characteristics are likely to occur.
The particle A has a 10% particle diameter (D 10 ) in a volume-based cumulative particle size distribution measured by a laser diffraction particle size distribution analyzer, preferably 80 nm or more, more preferably 100 nm or more. The particle A has a 50% particle size (D 50 ) in a volume-based cumulative particle size distribution measured by a laser diffraction particle size distribution analyzer, preferably 100 to 400 nm, more preferably 200 to 300 nm.
　粒度分布を調整するために、公知の粉砕方法及び／又は分級方法を利用することができる。粉砕装置としては、例えば、ハンマーミル、ジョークラッシャー、衝突式粉砕器などが挙げられる。また、分級は気流分級及び／又は篩によって行うことができる。気流分級装置としては、例えば、ターボクライファイヤー、ターボプレックスなどが挙げられる。 In order to adjust the particle size distribution, a known pulverization method and / or classification method can be used. Examples of the pulverizer include a hammer mill, a jaw crusher, and a collision pulverizer. Moreover, classification can be performed by airflow classification and / or sieving. Examples of the airflow classifier include a turbo cryfire and a turboplex.
（炭素粒子Ｃ）
　負極材は、上記の粒子Ａに加えて、黒鉛材料を含有する炭素粒子Ｃをさらに含むことが好ましい。炭素粒子Ｃは、粒子Ａが１００質量部に対して、好ましくは２５０～２０００質量部、より好ましく２５０～５００質量部含まれる。
　炭素粒子Ｃは、体積基準累積粒度分布における５０％粒子径（Ｄ５０）が、好ましくは２～４０μｍ、より好ましくは２～１５μｍである。なお、この粒度分布の測定においては二次粒子の粒径も含まれている。体積基準累積粒度分布は、レーザー回折式粒度分布測定機によって測定することができる。 (Carbon particle C)
The negative electrode material preferably further includes carbon particles C containing a graphite material in addition to the particles A described above. The carbon particles C are contained in an amount of preferably 250 to 2000 parts by mass, more preferably 250 to 500 parts by mass with respect to 100 parts by mass of the particles A.
The carbon particles C have a 50% particle diameter (D 50 ) in a volume-based cumulative particle size distribution of preferably 2 to 40 μm, more preferably 2 to 15 μm. In the measurement of the particle size distribution, the particle size of secondary particles is also included. The volume-based cumulative particle size distribution can be measured by a laser diffraction particle size distribution measuring machine.
　また炭素粒子Ｃは、粒子径１～５０μｍの範囲にある粒子が数基準で９０％以上存在する粒度分布であることが好ましく、粒子径５～５０μｍの範囲にある粒子が数基準で９０％以上存在する粒度分布であることが好ましい。炭素粒子Ｃは、レーザー回折式粒度分布測定機によって測定される体積基準累積粒度分布における１０％粒子径（Ｄ１０）が、好ましくは１μｍ以上、より好ましくは２μｍ以上である。 The carbon particles C preferably have a particle size distribution in which 90% or more of particles having a particle diameter in the range of 1 to 50 μm are present on a number basis, and 90% or more of particles having a particle diameter in the range of 5 to 50 μm on the number basis It is preferable that the particle size distribution exists. The carbon particles C have a 10% particle diameter (D 10 ) in a volume-based cumulative particle size distribution measured by a laser diffraction particle size distribution analyzer, preferably 1 μm or more, more preferably 2 μm or more.
　炭素粒子Ｃは、黒鉛材料のみからなる粒子（すなわち、黒鉛粒子）であってもよいし、黒鉛粒子とその表面に存在する炭素質層とからなる粒子（すなわち、炭素被覆黒鉛粒子）であってもよいし、炭素被覆黒鉛粒子または黒鉛粒子に炭素繊維を付着させてなる粒子であってもよい。 The carbon particles C may be particles composed only of graphite material (that is, graphite particles), or particles composed of graphite particles and a carbonaceous layer existing on the surface thereof (that is, carbon-coated graphite particles). Alternatively, carbon-coated graphite particles or particles obtained by attaching carbon fibers to graphite particles may be used.
　黒鉛材料としては、人造黒鉛、熱分解黒鉛、膨張黒鉛、天然黒鉛、鱗状黒鉛、鱗片状黒鉛などが挙げられる。これらのうち人造黒鉛が好ましい。
　炭素被覆黒鉛粒子表面の炭素質層は、ラマン分光スペクトルで測定される１３００～１４００ｃｍ－１の範囲にある非晶質成分由来のピークの強度（ＩＤ）と１５８０～１６２０ｃｍ－１の範囲にある黒鉛成分由来のピークの強度（ＩＧ）との比ＩＤ／ＩＧ（Ｒ値）が好ましくは０．１以上、より好ましくは０．２以上である。 Examples of the graphite material include artificial graphite, pyrolytic graphite, expanded graphite, natural graphite, scaly graphite, and scaly graphite. Of these, artificial graphite is preferred.
The carbonaceous layer on the surface of the carbon-coated graphite particles has a peak intensity (I D ) derived from an amorphous component in the range of 1300 to 1400 cm −1 and a range of 1580 to 1620 cm −1 as measured by Raman spectroscopy. The ratio I D / I G (R value) with the peak intensity (I G ) derived from the graphite component is preferably 0.1 or more, more preferably 0.2 or more.
　炭素被覆黒鉛粒子は、公知の方法に従って製造することができる。例えば、微粉化された黒鉛粒子に等方性ピッチ、異方性ピッチ、樹脂又は樹脂前駆体若しくはモノマーなどの有機化合物を吹きかけながら前記黒鉛粒子を撹拌する。またはハイブリダイザーなどの装置により、黒鉛粒子と、ピッチやフェノール樹脂などの有機化合物とを混合してメカノケミカル処理を行う。有機化合物の付着量は、黒鉛粒子１００質量部に対して、好ましくは０．０５～１０質量部、より好ましくは０．１～１０質量部である。次いで、有機化合物が付着された黒鉛粒子を、好ましくは２００℃以上２０００℃以下、より好ましくは５００℃以上１５００℃以下で熱処理する。この熱処理によって炭素被覆黒鉛粒子が得られる。 Carbon-coated graphite particles can be produced according to a known method. For example, the graphite particles are agitated while spraying an organic compound such as an isotropic pitch, an anisotropic pitch, a resin, a resin precursor, or a monomer to the finely divided graphite particles. Alternatively, the graphite particles and an organic compound such as pitch or phenol resin are mixed and mechanochemical treatment is performed using a device such as a hybridizer. The adhesion amount of the organic compound is preferably 0.05 to 10 parts by mass, more preferably 0.1 to 10 parts by mass with respect to 100 parts by mass of the graphite particles. Next, the graphite particles to which the organic compound is adhered are preferably heat-treated at 200 ° C. or higher and 2000 ° C. or lower, more preferably 500 ° C. or higher and 1500 ° C. or lower. Carbon-coated graphite particles are obtained by this heat treatment.
　炭素繊維としては、気相法炭素繊維、石油ピッチ系炭素繊維、石炭ピッチ系炭素繊維、ＰＡＮ系炭素繊維などが挙げられる。これらのうち気相法炭素繊維が好ましい。黒鉛粒子または炭素被覆黒鉛粒子の表面に炭素繊維を結着（接着）させる方法に特に制限はない。
　例えば、炭素繊維を有機化合物に混ぜて、それを黒鉛粒子または炭素被覆黒鉛粒子に付着させ、次いで熱処理を行うことによって、炭素質層の形成過程で炭素繊維を炭素質層に結着させることができる。炭素繊維の量は、黒鉛粒子１００質量部に対して、好ましくは０．１～２０質量部、より好ましくは０．１～１５質量部である。 Examples of the carbon fiber include vapor grown carbon fiber, petroleum pitch-based carbon fiber, coal pitch-based carbon fiber, and PAN-based carbon fiber. Of these, vapor grown carbon fiber is preferred. There is no particular limitation on the method for binding (adhering) the carbon fibers to the surface of the graphite particles or carbon-coated graphite particles.
For example, by mixing carbon fiber with an organic compound, attaching it to graphite particles or carbon-coated graphite particles, and then performing a heat treatment, the carbon fiber can be bound to the carbonaceous layer in the process of forming the carbonaceous layer. it can. The amount of the carbon fiber is preferably 0.1 to 20 parts by mass, more preferably 0.1 to 15 parts by mass with respect to 100 parts by mass of the graphite particles.
＜バインダー＞
　本発明の一実施形態に係るスラリーに用いるバインダーは、スチレン、エチレン性不飽和カルボン酸エステル、エチレン性不飽和カルボン酸及び少なくとも一つのエチレン性不飽和基を有する架橋剤を必須成分として含有するエチレン性不飽和単量体を重合することで得られる重合体Ｂを含む。
　バインダーは、負極材１００質量部に対し、好ましくは１～１００質量部、より好ましくは１～２０質量部含まれる。 <Binder>
The binder used in the slurry according to one embodiment of the present invention is ethylene containing, as essential components, a styrene, an ethylenically unsaturated carboxylic acid ester, an ethylenically unsaturated carboxylic acid, and a crosslinking agent having at least one ethylenically unsaturated group. A polymer B obtained by polymerizing a polymerizable unsaturated monomer.
The binder is contained in an amount of preferably 1 to 100 parts by weight, more preferably 1 to 20 parts by weight, based on 100 parts by weight of the negative electrode material.
（重合体Ｂ）（スチレン）
　重合体Ｂ中、スチレンを必須成分とする理由は、負極材同士の結着性を発現させるためである。特に負極材として上述の炭素粒子Ｃを含むものを用いた場合、より一層その効果を発現することができる。スチレンの使用量としては全エチレン性不飽和単量体に対して好ましくは３０～７０質量％であり、より好ましくは、４０～６０質量％である。スチレンの使用量を３０質量％以上とすることにより、負極材同士の結着性が向上し、負極材と集電体との密着力が向上する。一方、スチレン使用量を７０質量％以下とすると、重合体Ｂのガラス転移温度（Ｔｇ）が適正範囲となり、負極用スラリーの塗布から得られた負極に割れが発生しにくい。なお、全エチレン性不飽和単量体には、後述のエチレン性不飽和基を有する界面活性剤は含まない。 (Polymer B) (Styrene)
The reason why styrene is an essential component in the polymer B is to develop binding properties between the negative electrode materials. In particular, when the negative electrode material containing the above-described carbon particles C is used, the effect can be further exhibited. The amount of styrene used is preferably 30 to 70% by mass, more preferably 40 to 60% by mass, based on the total ethylenically unsaturated monomer. By setting the amount of styrene to be 30% by mass or more, the binding property between the negative electrode materials is improved, and the adhesion between the negative electrode material and the current collector is improved. On the other hand, when the amount of styrene used is 70% by mass or less, the glass transition temperature (Tg) of the polymer B falls within an appropriate range, and cracking is unlikely to occur in the negative electrode obtained from application of the slurry for negative electrode. The total ethylenically unsaturated monomer does not include a surfactant having an ethylenically unsaturated group described later.
（エチレン性不飽和カルボン酸エステル）
　重合体Ｂの原料となるエチレン性不飽和カルボン酸エステルは、ヒドロキシ基、グリシジル基などの極性基を有するエチレン性不飽和カルボン酸エステルを含有することが好ましく、これらは得られるバインダーの乳化重合安定性または機械的安定性を向上させる目的で用いられる。具体的には例えば、（メタ）アクリル酸２－ヒドロキシエチル、（メタ）アクリル酸２－ヒドロキシプロピル等の（メタ）アクリル酸２－ヒドロキシアルキル、アクリル酸グリシジル等が挙げられる。これらの中でも、（メタ）アクリル酸２－ヒドロキシエチルが好ましい。 (Ethylenically unsaturated carboxylic acid ester)
The ethylenically unsaturated carboxylic acid ester used as the raw material of the polymer B preferably contains an ethylenically unsaturated carboxylic acid ester having a polar group such as a hydroxy group or a glycidyl group. Used for the purpose of improving the stability or mechanical stability. Specific examples include 2-hydroxyalkyl (meth) acrylate such as 2-hydroxyethyl (meth) acrylate and 2-hydroxypropyl (meth) acrylate, glycidyl acrylate, and the like. Of these, 2-hydroxyethyl (meth) acrylate is preferred.
　極性基を有するエチレン性不飽和カルボン酸エステルの使用量としては、全エチレン性不飽和単量体に対して好ましくは０．１～１０質量％であり、好ましくは、０．５～５質量％である。極性基を有するエチレン性不飽和カルボン酸の使用量を０．１質量％以上とすることで、重合安定性または機械的安定性が向上し、また、電解液に対する乾燥皮膜の耐膨潤性が向上する傾向にあり、１０質量％以下とすると、負極材同士及び負極材と集電体との結着性が向上する傾向がある。 The amount of the ethylenically unsaturated carboxylic acid ester having a polar group is preferably 0.1 to 10% by mass, preferably 0.5 to 5% by mass, based on the total ethylenically unsaturated monomers. It is. By using the ethylenically unsaturated carboxylic acid having a polar group in an amount of 0.1% by mass or more, the polymerization stability or mechanical stability is improved, and the swelling resistance of the dry film against the electrolytic solution is improved. When the content is 10% by mass or less, the binding property between the negative electrode materials and between the negative electrode material and the current collector tends to be improved.
　エチレン性不飽和カルボン酸エステルは、上記以外のもの（その他のエチレン性不飽和カルボン酸エステルとする）を含んでもよい。例えば、（メタ）アクリル酸メチル、（メタ）アクリル酸エチル、（メタ）アクリル酸ｎ－プロピル、（メタ）アクリル酸イソプロピル、（メタ）アクリル酸ｎ－ブチル、（メタ）アクリル酸ｉｓｏ－ブチル、（メタ）アクリル酸ｔｅｒｔ－ブチル、（メタ）アクリル酸ｎ－ヘキシル、（メタ）アクリル酸２－エチルヘキシル、（メタ）アクリル酸ラウリル、（メタ）アクリル酸ステアリル、（メタ）アクリル酸シクロヘキシル、(メタ)アクリル酸イソノニル、（メタ）アクリル酸イソボロニル、(メタ)アクリル酸ベンジル等の（メタ）アクリル酸エステル類が挙げられる。これらの中でも、乳化重合の容易さや耐久性の観点から、（メタ）アクリル酸ｎ－ブチル、（メタ）アクリル酸２－エチルヘキシル、（メタ）アクリル酸ラウリル、（メタ）アクリル酸イソボロニルが好ましい。 The ethylenically unsaturated carboxylic acid ester may include those other than the above (referred to as other ethylenically unsaturated carboxylic acid ester). For example, methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, iso-butyl (meth) acrylate, Tert-butyl (meth) acrylate, n-hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, lauryl (meth) acrylate, stearyl (meth) acrylate, cyclohexyl (meth) acrylate, (meth And (meth) acrylic acid esters such as isononyl acrylate, isobornyl (meth) acrylate, and benzyl (meth) acrylate. Among these, n-butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, lauryl (meth) acrylate, and isobornyl (meth) acrylate are preferred from the viewpoint of ease of emulsion polymerization and durability.
　その他のエチレン性不飽和カルボン酸エステルの使用量としては、全エチレン性不飽和単量体に対して好ましくは２５～８５質量％であり、より好ましくは、３０～８０質量％である。エチレン性不飽和カルボン酸エステルの使用量を２５質量％以上とすると、得られる負極の柔軟性や耐熱性が向上する傾向にあり、８５質量％以下とすると、負極材同士及び負極材と集電体との結着性が向上する傾向がある。 The amount of other ethylenically unsaturated carboxylic acid ester used is preferably 25 to 85% by mass, more preferably 30 to 80% by mass, based on the total ethylenically unsaturated monomer. When the amount of the ethylenically unsaturated carboxylic acid ester used is 25% by mass or more, flexibility and heat resistance of the obtained negative electrode tend to be improved, and when it is 85% by mass or less, the negative electrode materials and the negative electrode material and the current collector are collected. There is a tendency to improve the binding with the body.
（エチレン性不飽和カルボン酸）
　エチレン性不飽和カルボン酸の具体的な例としては、アクリル酸、メタクリル酸、クロトン酸等の不飽和モノカルボン酸、マレイン酸、フマル酸、イタコン酸等の不飽和ジカルボン酸またはこれら不飽和ジカルボン酸のハーフエステル等が挙げられ、これらの中でも、アクリル酸、イタコン酸が好ましい。これらのエチレン性不飽和カルボン酸は１種単独で使用してもよいし、２種以上を組み合わせて使用してもよい。 (Ethylenically unsaturated carboxylic acid)
Specific examples of the ethylenically unsaturated carboxylic acid include unsaturated monocarboxylic acids such as acrylic acid, methacrylic acid, and crotonic acid, unsaturated dicarboxylic acids such as maleic acid, fumaric acid, and itaconic acid, or unsaturated dicarboxylic acids thereof. Of these, and among them, acrylic acid and itaconic acid are preferable. These ethylenically unsaturated carboxylic acids may be used individually by 1 type, and may be used in combination of 2 or more type.
　エチレン性不飽和カルボン酸の使用量は、重合体Ｂの酸価が、好ましくは６～１００、より好ましくは６～５０になる範囲である。酸価を６以上とすると、乳化重合安定性または機械的安定性が向上し、また、得られる負極の耐熱性が向上する傾向にあり、更には、負極材である、リチウムイオンを吸蔵・放出可能な元素を含む炭素以外の粒子Ａとの親和性、結着力が向上する。一方、酸価を１００以下とすると、特に負極材として炭素粒子Ｃを含むものを用いる場合、負極材同士及び負極材と集電体との結着性が向上する傾向がある。酸価とは、樹脂１ｇ中に存在するカルボン酸を中和するのに必要な水酸化カリウムのｍｇ数である。酸価はＪＩＳ　Ｋ５６０１－２－１に従って測定を行い、下記式（１）で求めることができる。 The amount of the ethylenically unsaturated carboxylic acid used is such that the acid value of the polymer B is preferably 6 to 100, more preferably 6 to 50. When the acid value is 6 or more, emulsion polymerization stability or mechanical stability is improved, and the heat resistance of the obtained negative electrode tends to be improved. Further, lithium ion, which is a negative electrode material, is occluded / released. Affinity and binding force with particles A other than carbon containing possible elements are improved. On the other hand, when the acid value is 100 or less, particularly when a material containing carbon particles C is used as the negative electrode material, the binding properties between the negative electrode materials and between the negative electrode material and the current collector tend to be improved. The acid value is the number of mg of potassium hydroxide necessary to neutralize the carboxylic acid present in 1 g of resin. The acid value is measured according to JIS K5601-2-1 and can be obtained by the following formula (1).
　酸価＝（カルボン酸の価数）×（エチレン性不飽和カルボン酸の質量％）÷（エチレン性不飽和カルボン酸の分子量）×５６．１×１０００・・・（１） Acid value = (valence of carboxylic acid) × (mass% of ethylenically unsaturated carboxylic acid) ÷ (molecular weight of ethylenically unsaturated carboxylic acid) × 56.1 × 1000 (1)
　所望の酸価が得られるエチレン性不飽和カルボン酸の使用量は、重合体Ｂの製造に使用するエチレン性不飽和単量体の種類や比率によって異なるが、通常、全エチレン性不飽和単量体に対して好ましくは１～１０質量％であり、より好ましくは、１～５質量％である。 The amount of the ethylenically unsaturated carboxylic acid that provides the desired acid value varies depending on the type and ratio of the ethylenically unsaturated monomer used in the production of the polymer B. The amount is preferably 1 to 10% by mass, more preferably 1 to 5% by mass based on the body.
（架橋剤）
　さらに、得られるリチウムイオン電池負極の電解液溶剤に対する耐膨潤性をより向上させるために、重合体Ｂの製造には、少なくとも一つのエチレン性不飽和結合を有する架橋剤が用いられる。架橋剤は、カルボキシル基と反応する基を有するもの、或いは、２つ以上のエチレン性不飽和基を有するものであればよい。架橋剤としては、ジビニルベンゼン、エチレングリコールジ（メタ）アクリレート、トリメチロールプロパントリ（メタ）アクリレート、トリアリルシアヌレート等のエチレン性不飽和基を２個以上有する単量体、ビニルトリメトキシシラン、ビニルトリエトキシシラン、γ－メタクリオキシプロピルトリメトキシシラン、γ－メタクリオキシプロピルトリエトキシシラン等の、エチレン性不飽和基を有するシランカップリング剤等が挙げられ、これらの中でも、ジビニルベンゼンが好ましい。これらの架橋剤は１種単独で使用してもよいし、２種以上を組み合わせて使用してもよい。 (Crosslinking agent)
Furthermore, in order to further improve the swelling resistance of the obtained lithium ion battery negative electrode with respect to the electrolyte solvent, a cross-linking agent having at least one ethylenically unsaturated bond is used in the production of the polymer B. The cross-linking agent may be one having a group that reacts with a carboxyl group or one having two or more ethylenically unsaturated groups. As the crosslinking agent, monomers having two or more ethylenically unsaturated groups such as divinylbenzene, ethylene glycol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, triallyl cyanurate, vinyltrimethoxysilane, Examples thereof include silane coupling agents having an ethylenically unsaturated group such as vinyltriethoxysilane, γ-methacryloxypropyltrimethoxysilane, and γ-methacryloxypropyltriethoxysilane. Among these, divinylbenzene is preferable. These crosslinking agents may be used alone or in combination of two or more.
　架橋剤の使用量としては、全エチレン性不飽和単量体に対して好ましくは０．１～５質量％であり、より好ましくは、０．１～３質量％である。架橋剤の使用量が０．１質量％以上であると、電解液に対する乾燥皮膜の耐膨潤性が向上する傾向にあり、５質量％以下であると、乳化重合安定性が向上し、また、負極材と集電体の密着力が向上する傾向にある。 The amount of the crosslinking agent used is preferably 0.1 to 5% by mass and more preferably 0.1 to 3% by mass with respect to the total ethylenically unsaturated monomer. When the amount of the crosslinking agent used is 0.1% by mass or more, the swelling resistance of the dry film to the electrolytic solution tends to be improved, and when it is 5% by mass or less, the emulsion polymerization stability is improved. The adhesion between the negative electrode material and the current collector tends to be improved.
（その他のエチレン性不飽和単量体）
　また、本発明の目的を損なわない範囲で、少なくとも１つの重合可能なエチレン性不飽和基を有する化合物を、エチレン性不飽和単量体として用いてもよい。
　例えば、アミド基、ニトリル基などの極性基を有する化合物として、（メタ）アクリルアミド、Ｎ－メチロール（メタ）アクリルアミド、（メタ）アクリロニトリル及びＮ－ビニルピロリドン等が挙げられる。
　また酢酸ビニルやプロピオン酸ビニルを用いることもできる。 (Other ethylenically unsaturated monomers)
In addition, a compound having at least one polymerizable ethylenically unsaturated group may be used as the ethylenically unsaturated monomer as long as the object of the present invention is not impaired.
Examples of the compound having a polar group such as an amide group and a nitrile group include (meth) acrylamide, N-methylol (meth) acrylamide, (meth) acrylonitrile, N-vinylpyrrolidone and the like.
Vinyl acetate and vinyl propionate can also be used.
（重合体Ｂ中の他の成分）
　さらに、分子量を調整するためにメルカプト基を有する化合物、チオグリコール酸及びそのエステル、β－メルカプトプロピオン酸及びそのエステルなどを用いてもよい。 (Other components in polymer B)
Further, a compound having a mercapto group, thioglycolic acid and its ester, β-mercaptopropionic acid and its ester may be used for adjusting the molecular weight.
（重合体Ｂの特性）
　上記重合体ＢのＴｇは、３０℃以下であることが好ましい。Ｔｇが３０℃以下であると、負極用スラリーの塗布から得られた負極に割れが発生し、好ましくない。
　さらに、上記重合体Ｂは、６０℃のプロピレンカーボネート、ジエチルカーボネート系電解液溶剤に対する乾燥皮膜の耐膨潤率が、好ましくは３００％以下であり、より好ましくは、５％～２００％である。６０℃の電解液に対する乾燥皮膜の耐膨潤率が３００％以下であると、高温時の充放電高温サイクル特性が低下し、好ましい。 (Characteristics of polymer B)
The Tg of the polymer B is preferably 30 ° C. or lower. When Tg is 30 ° C. or lower, cracks occur in the negative electrode obtained from the application of the slurry for negative electrode, which is not preferable.
Further, the above polymer B has a dry film swelling ratio of preferably 300% or less, more preferably 5% to 200%, with respect to a solvent of propylene carbonate / diethyl carbonate electrolyte at 60 ° C. It is preferable that the swelling resistance of the dry film with respect to the electrolytic solution at 60 ° C. is 300% or less because charge / discharge high temperature cycle characteristics at high temperatures are lowered.
（重合体Ｂの製造）
　スラリーに用いる重合体Ｂは、上述のエチレン性不飽和単量体を重合して得られる。通常、重合は界面活性剤の存在下、水を分散媒として乳化重合で行われ、重合体Ｂを含む水性エマルジョンを得る。 (Production of polymer B)
The polymer B used for the slurry is obtained by polymerizing the above ethylenically unsaturated monomer. Usually, the polymerization is carried out by emulsion polymerization using water as a dispersion medium in the presence of a surfactant to obtain an aqueous emulsion containing the polymer B.
（界面活性剤）
　重合の際に用いられる反応性界面活性剤としては、通常のアニオン性界面活性剤、ノニオン性界面活性剤であれば特に制限されるものではない。アニオン性界面活性剤としては、例えば、アルキルベンゼンスルホン酸塩、アルキル硫酸エステル塩、ポリオキシエチレンアルキルエーテル硫酸エステル塩、脂肪酸塩等が挙げられ、ノニオン界面活性剤としては、ポリオキシエチレンアルキルエーテル、ポリオキシエチレンアルキルフェニルエーテル、ポリオキシエチレン多環フィニルエーテル、ポリオキシアルキレンアルキルエーテル、ソルビタン脂肪酸エステル、ポリオキシエチレンソルビタン脂肪酸エステル等が挙げられる。これらは１種単独で使用してもよいし、２種以上を組み合わせて使用してもよい。
　好ましい界面活性剤として、上記のうちエチレン性不飽和基を有するものが挙げられ、より好ましくは以下の式（２）～（５）で表されるものを挙げることができる。 (Surfactant)
The reactive surfactant used in the polymerization is not particularly limited as long as it is a normal anionic surfactant or nonionic surfactant. Examples of the anionic surfactant include alkyl benzene sulfonate, alkyl sulfate ester salt, polyoxyethylene alkyl ether sulfate ester salt, fatty acid salt, and the like. Nonionic surfactants include polyoxyethylene alkyl ether, polyoxyethylene alkyl ether, Examples thereof include oxyethylene alkyl phenyl ether, polyoxyethylene polycyclic finyl ether, polyoxyalkylene alkyl ether, sorbitan fatty acid ester, polyoxyethylene sorbitan fatty acid ester and the like. These may be used individually by 1 type and may be used in combination of 2 or more type.
Preferred surfactants include those having an ethylenically unsaturated group, and more preferred are those represented by the following formulas (2) to (5).
Figure JPOXMLDOC01-appb-C000001
 （式中、Ｒはアルキル基、ｎは１０～４０の整数である）
Figure JPOXMLDOC01-appb-C000001
 (Wherein R is an alkyl group, and n is an integer of 10 to 40)
Figure JPOXMLDOC01-appb-C000002
 （式中、ｎは１０～１２の整数、ｍは１０～４０の整数である）
Figure JPOXMLDOC01-appb-C000002
 (In the formula, n is an integer of 10 to 12, and m is an integer of 10 to 40)
Figure JPOXMLDOC01-appb-C000003
 （式中、Ｒはアルキル基、ＭはＮＨ４またはＮａである）
Figure JPOXMLDOC01-appb-C000003
 (Wherein R is an alkyl group, M is NH 4 or Na)
Figure JPOXMLDOC01-appb-C000004
 （式中、Ｒはアルキル基、ＭはＮａである）
Figure JPOXMLDOC01-appb-C000004
 (Wherein R is an alkyl group, and M is Na)
　界面活性剤の使用量に特に制限はなく、例えば、エチレン性不飽和基を有する界面活性剤を用いる場合、好ましくは全エチレン性不飽和単量体に対して０．３～３質量％である。界面活性剤の使用量が０．３質量％以上であると、重合安定性が向上し、また得られる水性エマルジョンの粒子系が小さいため、樹脂エマルジョンの沈降が発生しにくい。また界面活性剤の使用量が３質量％以下であると、負極材と集電体の密着力が向上し、好ましい。 The amount of the surfactant used is not particularly limited. For example, when a surfactant having an ethylenically unsaturated group is used, it is preferably 0.3 to 3% by mass based on the total ethylenically unsaturated monomer. . When the amount of the surfactant used is 0.3% by mass or more, the polymerization stability is improved, and since the particle system of the obtained aqueous emulsion is small, the resin emulsion does not easily precipitate. Further, when the amount of the surfactant used is 3% by mass or less, the adhesion between the negative electrode material and the current collector is improved, which is preferable.
　重合の際に用いられるラジカル重合開始剤としては公知慣用のものであればよく、例えば、過硫酸塩や過酸化物が挙げられる。過硫酸塩としては、過硫酸アンモニウム、過硫酸カリウム等が挙げられ、過酸化物としては、過酸化水素の他、ｔ－ブチルハイドロパーオキサイド、クメンハイドロパーオキサイド等の有機過酸化物が挙げられる。また、必要に応じて、これらの重合開始剤を重亜硫酸ナトリウム、ロンガリット、アスコルビン酸等の還元剤と併用してレドックス重合としてもよい。 The radical polymerization initiator used in the polymerization may be a known and conventional one, and examples thereof include persulfate and peroxide. Examples of the persulfate include ammonium persulfate and potassium persulfate, and examples of the peroxide include hydrogen peroxide and organic peroxides such as t-butyl hydroperoxide and cumene hydroperoxide. If necessary, these polymerization initiators may be used in combination with a reducing agent such as sodium bisulfite, Rongalite, and ascorbic acid for redox polymerization.
　重合法としては、一括して仕込む重合方法、各成分を連続供給しながら重合する方法などが適用される。重合は通常３０～９０℃の温度で攪拌下に行われる。尚エチレン性不飽和カルボン酸を重合中または重合終了後に塩基性物質を加えて、水性エマルジョンのｐＨを調整することにより、重合時の重合安定性、機械的安定性、化学的安定性を向上させることができる。 As the polymerization method, a polymerization method charged in a batch, a polymerization method while continuously supplying each component, and the like are applied. The polymerization is usually carried out at a temperature of 30 to 90 ° C. with stirring. By adding a basic substance during or after the polymerization of ethylenically unsaturated carboxylic acid, the pH of the aqueous emulsion is adjusted to improve the polymerization stability, mechanical stability, and chemical stability during polymerization. be able to.
　この場合に使用される塩基性物質としては、アンモニア、トリエチルアミン、エタノールアミン、苛性ソーダ等を使用することができる。これらは１種単独で使用してもよいし、２種以上を組み合わせて使用してもよい。 As the basic substance used in this case, ammonia, triethylamine, ethanolamine, caustic soda and the like can be used. These may be used individually by 1 type and may be used in combination of 2 or more type.
（重合体Ｂ以外のバインダー成分）
　本発明の目的を損なわない範囲で、バインダーは上述の重合体Ｂ以外の成分を含んでもよい。他の成分の例としては、カルボキシメチルセルロース、メチルセルロース、ヒドロキシメチルセルロース、エチルセルロース、ポリビニルアルコール、ポリアクリル酸（塩）、酸化スターチ、リン酸化スターチ、カゼインなどが挙げられる。これら他のバインダー成分の使用量は、重合体Ｂ１００質量部に対し、好ましくは５～２００質量部、より好ましくは５０～１５０質量部である。 (Binder components other than polymer B)
As long as the object of the present invention is not impaired, the binder may contain components other than the polymer B described above. Examples of other components include carboxymethylcellulose, methylcellulose, hydroxymethylcellulose, ethylcellulose, polyvinyl alcohol, polyacrylic acid (salt), oxidized starch, phosphorylated starch, and casein. The amount of these other binder components used is preferably 5 to 200 parts by weight, more preferably 50 to 150 parts by weight, based on 100 parts by weight of the polymer B.
＜分散媒＞
　スラリーは、水を含む分散媒を含む。分散媒に含まれる水は、通常、上述の重合体Ｂを含む水性エマルジョンに由来するものであるが、それに限定されず、スラリーの粘度等によって、適宜、量を調整することができる。
　分散媒は、本発明の目的を損ねない範囲で、水と混和する有機溶媒を含んでもよい。例えば、Ｎ，Ｎ－ジメチルホルムアミド、Ｎ，Ｎ－ジメチルアセトアミド、Ｎ－メチルピロリドン、メタノール、イソプロピルアルコール、ブタノール、アセトン、２－ブタノン、シクロヘキサノンなどが挙げられる。これら有機溶媒を使用する場合、その使用量は、分散媒中、好ましくは１～５０質量％、より好ましくは１～２０質量％であり、使用しなくてもよい。 <Dispersion medium>
The slurry contains a dispersion medium containing water. The water contained in the dispersion medium is usually derived from the aqueous emulsion containing the above-mentioned polymer B, but is not limited thereto, and the amount can be appropriately adjusted depending on the viscosity of the slurry.
The dispersion medium may contain an organic solvent miscible with water as long as the object of the present invention is not impaired. Examples thereof include N, N-dimethylformamide, N, N-dimethylacetamide, N-methylpyrrolidone, methanol, isopropyl alcohol, butanol, acetone, 2-butanone and cyclohexanone. When these organic solvents are used, the amount used is preferably 1 to 50% by mass, more preferably 1 to 20% by mass in the dispersion medium, and may not be used.
＜導電助剤＞
　スラリーは、導電助剤を含んでもよい。導電助剤は負極に対し導電性及び電極安定性（リチウムイオンの挿入・脱離における体積変化に対する緩衝作用）を付与する役目を果たすものであれば特に制限は無く、例えば、気相法炭素繊維（例えば、「ＶＧＣＦ」（登録商標）昭和電工社製）、導電性カーボン（例えば、「デンカブラック」（登録商標）電気化学工業社製、「Ｓｕｐｅｒ　Ｃ６５」ＴＩＭＣＡＬ社製、「Ｓｕｐｅｒ　Ｃ４５」ＴＩＭＣＡＬ社製、「ＫＳ６Ｌ」ＴＩＭＣＡＬ社製）などが挙げられる。導電助剤の量は、負極材１００質量部に対して、好ましくは１０～１５０質量部、より好ましくは５０～１００質量部である。 <Conductive aid>
The slurry may contain a conductive aid. The conductive auxiliary agent is not particularly limited as long as it has a function of imparting conductivity and electrode stability to the negative electrode (buffering action against volume change in insertion / extraction of lithium ions). For example, vapor grown carbon fiber (For example, “VGCF” (registered trademark) manufactured by Showa Denko KK), conductive carbon (for example, “Denka Black” (registered trademark) manufactured by Denki Kagaku Kogyo Co., Ltd., “Super C65” manufactured by TIMCAL, “Super C45” TIMCAL And “KS6L” manufactured by TIMCAL). The amount of the conductive auxiliary is preferably 10 to 150 parts by mass, more preferably 50 to 100 parts by mass with respect to 100 parts by mass of the negative electrode material.
＜スラリーの製造方法＞
　本発明の一実施形態に係るリチウムイオン電池電極用スラリーは、上述の各成分を混合して得られる。混合の方法には特に制限は無く、リチウムイオン電池の製造に用いられる公知の方法を用いることができる。例えば、上述の重合体Ｂを含む水性エマルジョンに、負極材と導電助剤とを加えて、さらに、分散、溶解または混練する方法があげられる。 <Method for producing slurry>
The slurry for a lithium ion battery electrode according to an embodiment of the present invention is obtained by mixing the above-described components. There is no restriction | limiting in particular in the method of mixing, The well-known method used for manufacture of a lithium ion battery can be used. For example, a method of adding a negative electrode material and a conductive additive to the above-described aqueous emulsion containing the polymer B and further dispersing, dissolving, or kneading can be mentioned.
［リチウムイオン電池用負極］
　本発明の一実施形態に係るリチウムイオン電池用負極は、集電体と、負極合材層とを有する。リチウムイオン電池用負極の厚さは、通常、５０～２００μｍである。
　集電体としては例えば、ニッケル、銅、アルミニウム及びこれらの合金からなる金属箔を用いることができる。金属箔は、孔のない通常の箔であっても、パンチングメタル箔、金属メッシュ、多孔質箔など、孔のある箔であってもよい。
　また必要に応じて、公知の導電層（例えば特開２００６－３２９０２号公報、特開２００８－６００６０号公報、特開２０１２－７２３９６号公報、国際公開パンフレットＷＯ２００９／１４７９８９号、国際公開パンフレットＷＯ２０１１／０２４７９８号、国際公開パンフレットＷＯ２０１１／０２４７９９号、国際公開パンフレットＷＯ２０１２／０２９８５８号、国際公開パンフレットＷＯ２０１２／９６１８９号を参照）が形成されたものでもよい。 [Anode for lithium ion batteries]
A negative electrode for a lithium ion battery according to an embodiment of the present invention includes a current collector and a negative electrode mixture layer. The thickness of the negative electrode for a lithium ion battery is usually 50 to 200 μm.
As the current collector, for example, a metal foil made of nickel, copper, aluminum, or an alloy thereof can be used. The metal foil may be a normal foil without holes, or a foil with holes such as a punching metal foil, a metal mesh, or a porous foil.
If necessary, a known conductive layer (for example, Japanese Patent Application Laid-Open No. 2006-32902, Japanese Patent Application Laid-Open No. 2008-60060, Japanese Patent Application Laid-Open No. 2012-72396, International Publication Pamphlet WO 2009/147989, International Publication Pamphlet WO 2011/024798). No., International Publication Pamphlet WO2011 / 024799, International Publication Pamphlet WO2012 / 029858, and International Publication Pamphlet WO2012 / 96189) may be formed.
　負極合材層は、上述の負極材、バインダー及び必要に応じて導電助剤を含む。その組成比は、負極材１００質量部に対し、バインダーが好ましくは１～１００質量部、より好ましくは１～２０質量部、導電助剤が好ましくは１０～１５０質量部、より好ましくは５０～１００質量部である。
　リチウムイオン電池用負極はこの他、必要に応じて保護層（例えば特開２００８－２２６５６６号公報、特開２００９－１８１７５６号公報、特開２０１０－２４４８１８号公報を参照）など、他の層を有していてもよい。 The negative electrode mixture layer includes the above-described negative electrode material, a binder, and, if necessary, a conductive additive. The composition ratio is preferably 1 to 100 parts by weight, more preferably 1 to 20 parts by weight, and preferably 10 to 150 parts by weight, more preferably 50 to 100 parts by weight of the conductive auxiliary, with respect to 100 parts by weight of the negative electrode material. Part by mass.
In addition to this, the negative electrode for a lithium ion battery has other layers such as a protective layer (see, for example, JP-A-2008-226666, JP-A-2009-181756, and JP-A-2010-244818) as necessary. You may do it.
　リチウムイオン電池用負極は、例えば、上述のスラリーを集電体に塗布し乾燥させることによって得ることができる。スラリーの塗布方法は特に制限されない。スラリーの塗布量によって、上述のリチウムイオン電池用負極の厚さを調整できる。また、負極用スラリーを乾燥させた後、加圧成形することによっても調整することができる。加圧成形法としては、ロール加圧、プレス加圧などの成形法が挙げられる。加圧成形するときの圧力は、好ましくは約１００ＭＰａ～約３００ＭＰａ（１～３ｔｏｎ／ｃｍ２程度）である。 The negative electrode for a lithium ion battery can be obtained, for example, by applying the above slurry to a current collector and drying it. The method for applying the slurry is not particularly limited. The thickness of the negative electrode for a lithium ion battery described above can be adjusted by the amount of slurry applied. Moreover, after drying the slurry for negative electrodes, it can also adjust by carrying out pressure molding. Examples of the pressure molding method include molding methods such as roll pressing and press pressing. The pressure during pressure molding is preferably about 100 MPa to about 300 MPa (about 1 to 3 ton / cm 2 ).
［リチウムイオン電池］
　本発明の一実施形態に係るリチウムイオン電池は、非水系電解液及び非水系ポリマー電解質からなる群から選ばれる少なくとも一つ、正極、及び上述の負極を有するものである。
　正極には、リチウムイオン電池に従来から使われていたもの、具体的には正極活物質を含んでなるシートを用いることができる。正極活物質としては、ＬｉＮｉＯ２、ＬｉＣｏＯ２、ＬｉＭｎ２Ｏ４、ＬｉＮｉ０．３４Ｍｎ０．３３Ｃｏ０．３３Ｏ２、ＬｉＦｅＰＯ４などが挙げられる。 [Lithium ion battery]
A lithium ion battery according to an embodiment of the present invention has at least one selected from the group consisting of a non-aqueous electrolyte and a non-aqueous polymer electrolyte, a positive electrode, and the above-described negative electrode.
As the positive electrode, a sheet conventionally used for lithium ion batteries, specifically, a sheet containing a positive electrode active material can be used. Examples of the positive electrode active material include LiNiO 2 , LiCoO 2 , LiMn 2 O 4 , LiNi 0.34 Mn 0.33 Co 0.33 O 2 , and LiFePO 4 .
　リチウムイオン電池に用いられる非水系電解液及び非水系ポリマー電解質は特に制限されない。例えば、ＬｉＣｌＯ４、ＬｉＰＦ６、ＬｉＡｓＦ６、ＬｉＢＦ４、ＬｉＳＯ３ＣＦ３、ＣＨ３ＳＯ３Ｌｉ、ＣＦ３ＳＯ３Ｌｉなどのリチウム塩を、エチレンカーボネート、ジエチルカーボネート、ジメチルカーボネート、エチルメチルカーボネート、プロピレンカーボネート、ブチレンカーボネート、アセトニトリル、プロピロニトリル、ジメトキシエタン、テトラヒドロフラン、γ－ブチロラクトンなどの非水系溶媒に溶かしてなる有機電解液や；ポリエチレンオキシド、ポリアクリルニトリル、ポリフッ化ビリニデン、及びポリメチルメタクリレートなどを含有するゲル状のポリマー電解質や；エチレンオキシド結合を有するポリマーなどを含有する固体状のポリマー電解質が挙げられる。 The non-aqueous electrolyte and non-aqueous polymer electrolyte used for the lithium ion battery are not particularly limited. For example, a lithium salt such as LiClO 4 , LiPF 6 , LiAsF 6 , LiBF 4 , LiSO 3 CF 3 , CH 3 SO 3 Li, CF 3 SO 3 Li, ethylene carbonate, diethyl carbonate, dimethyl carbonate, ethyl methyl carbonate, propylene Organic electrolytes dissolved in non-aqueous solvents such as carbonate, butylene carbonate, acetonitrile, propyronitrile, dimethoxyethane, tetrahydrofuran, and γ-butyrolactone; polyethylene oxide, polyacrylonitrile, polyvinylidene fluoride, polymethyl methacrylate, etc. Examples thereof include a gel polymer electrolyte and a solid polymer electrolyte containing a polymer having an ethylene oxide bond.
　また、電解液には、リチウムイオン電池の初回充電時に分解反応が起きる物質を少量添加してもよい。該物質としては、例えば、ビニレンカーボネート、ビフェニール、プロパンスルトンなどが挙げられる。添加量としては０．０１～５質量％が好ましい。 In addition, a small amount of a substance that causes a decomposition reaction when the lithium ion battery is initially charged may be added to the electrolytic solution. Examples of the substance include vinylene carbonate, biphenyl, propane sultone, and the like. The addition amount is preferably 0.01 to 5% by mass.
　リチウムイオン電池には正極と負極との間にセパレータを設けることができる。セパレータとしては、例えば、ポリエチレン、ポリプロピレンなどのポリオレフィンを主成分とした不織布、クロス、微孔フィルム又はそれらを組み合わせたものなどが挙げられる。セパレータの表面には、公知の無機粒子層（例えば特開２００１－３１９６３４号公報、国際公開パンフレットＷＯ２００７／０６６７６８号、特開２００８－１２６９９６号公報、特開２００８－１２３９８８号公報を参照）が設けられていてもよい。 A lithium ion battery can be provided with a separator between the positive electrode and the negative electrode. Examples of the separator include non-woven fabrics, cloths, microporous films, or a combination thereof, mainly composed of polyolefins such as polyethylene and polypropylene. A known inorganic particle layer (see, for example, Japanese Patent Application Laid-Open No. 2001-319634, International Publication Pamphlet WO 2007/066768, Japanese Patent Application Laid-Open No. 2008-126996, Japanese Patent Application Laid-Open No. 2008-123988) is provided on the surface of the separator. It may be.
　図２は、本発明の一実施形態に係るリチウムイオン電池を示すもので、ここに示すリチウムイオン電池１０は、負極１と、これに対向する正極２と、負極１と正極２とを隔てるセパレータ３と、これらを収容する収容体４とを備えている。
　負極１は、集電体５と、集電体５の表面に設けられた負極合材層６とを有する。符号７は、収容体４内に注入された電解質である。収容体４は、負極１、正極２、およびセパレータ３を収容する本体４ａと、これを閉止する蓋体４ｂとからなる。 FIG. 2 shows a lithium ion battery according to an embodiment of the present invention. A lithium ion battery 10 shown here is a separator that separates a negative electrode 1, a positive electrode 2 opposite to the negative electrode 1, and the negative electrode 1 and the positive electrode 2. 3 and a container 4 for housing them.
The negative electrode 1 includes a current collector 5 and a negative electrode mixture layer 6 provided on the surface of the current collector 5. Reference numeral 7 denotes an electrolyte injected into the container 4. The container 4 includes a main body 4a that houses the negative electrode 1, the positive electrode 2, and the separator 3, and a lid 4b that closes the main body 4a.
　以下に実施例及び比較例を示して本発明をさらに詳細に説明するが、本発明はこれらによって限定されるものではない。なお、実施例及び比較例中の「部」及び「％」は、特に断りのない場合はそれぞれ質量部、質量％を示す。 Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited thereto. In the examples and comparative examples, “parts” and “%” respectively represent parts by mass and mass% unless otherwise specified.
（水性エマルジョンの合成）
　冷却管、温度計、攪拌機、滴下ロートを有するセパラブルフラスコに、イオン交換水１６０部及びアニオン性界面活性剤（三洋化成工業株式会社製、エレミノールＪＳ－２０（アルキルアリルスルホコハク酸ナトリウム）、４０％品）２部を仕込み、７５℃に昇温した。予めエレミノールＪＳ－２０を１０部、ハイテノール０８Ｅ（ポリオキシエチレンアルキルエーテル硫酸エステル塩、第一工業製薬株式会社製）２部、スチレン２５０部、アクリル酸２－エチルヘキシル２２０部、メタクリル酸２－ヒドロキシエチル１０部、ジビニルベンゼン１．５部、アクリル酸（８０％品）１５部、及びイオン交換水３９５部からなるモノマー乳化物を３時間かけて滴下した。同時に重合開始剤として過硫酸カリウム２部をイオン交換水５０部に溶解したものを３時間かけて８０℃で滴下重合した。滴下終了後、２時間熟成後冷却し、アンモニア水４．５部を添加して、重合体Ｂを含む水性エマルジョンを得た。得られた水性エマルジョンの不揮発分は４５．５％、粘度３０００ｍＰａ・ｓ、ｐＨ６．５であり、重合体Ｂの酸価は１８．９５であった。 (Synthesis of aqueous emulsion)
In a separable flask having a condenser, thermometer, stirrer, and dropping funnel, 160 parts of ion-exchanged water and an anionic surfactant (Sanyo Kasei Kogyo Co., Ltd., Eleminol JS-20 (sodium alkylallylsulfosuccinate), 40% Product) 2 parts were charged and heated to 75 ° C. 10 parts of Eleminol JS-20 in advance, 2 parts of Haitenol 08E (polyoxyethylene alkyl ether sulfate, Daiichi Kogyo Seiyaku Co., Ltd.), 250 parts of styrene, 220 parts of 2-ethylhexyl acrylate, 2-hydroxy methacrylate A monomer emulsion consisting of 10 parts of ethyl, 1.5 parts of divinylbenzene, 15 parts of acrylic acid (80% product), and 395 parts of ion-exchanged water was added dropwise over 3 hours. At the same time, 2 parts of potassium persulfate dissolved in 50 parts of ion exchange water as a polymerization initiator was dropped and polymerized at 80 ° C. over 3 hours. After completion of dropping, the mixture was aged for 2 hours and then cooled, and 4.5 parts of ammonia water was added to obtain an aqueous emulsion containing the polymer B. The obtained aqueous emulsion had a non-volatile content of 45.5%, a viscosity of 3000 mPa · s, a pH of 6.5, and the acid value of the polymer B was 18.95.
（負極材の調製）
　粒子Ａとして、Ｓｉ微粒子（Ａｌｆａ　Ａｅｓａｒ社製、ＣＡＳ７４４０－２１－３、製品番号４４３８４、一次粒子径５０ｎｍ以下）を用意した。炭素粒子Ｃとして、以下の手順で炭素被覆黒鉛粒子を調製した。
　石油系コークスを、平均粒子径５μｍとなるように粉砕した。これをアチソン炉にて３０００℃で熱処理して、黒鉛粒子を得た。次いで、黒鉛粒子に質量比１％で石油ピッチを混ぜて、黒鉛粒子表面に石油ピッチを付着させた。その後、不活性雰囲気下１１００℃で炭化処理した。ＢＥＴ比表面積が２．６ｍ２／ｇで、ｄ００２が０．３３６１ｎｍで、ＬＣが５９ｎｍで、１０％粒子径（Ｄ１０）が２．３μｍで、５０％粒子径（Ｄ５０）が５．７μｍで、９０％粒子径（Ｄ９０）が１１．８μｍで、且つＩＤ／ＩＧ（Ｒ値）が０．７７である炭素被覆黒鉛粒子が得られた。
　Ｓｉ微粒子を０．３７５ｇ及び炭素被覆黒鉛粒子Ｃを１．１２５ｇとり、乳鉢で混合して、Ｓｉ微粒子及び黒鉛粒子が複合化された負極材を得た。 (Preparation of negative electrode material)
As particles A, Si fine particles (Alfa Aesar, CAS7440-21-3, product number 44384, primary particle size of 50 nm or less) were prepared. As carbon particles C, carbon-coated graphite particles were prepared by the following procedure.
Petroleum coke was pulverized to an average particle size of 5 μm. This was heat-treated at 3000 ° C. in an Atchison furnace to obtain graphite particles. Next, petroleum pitch was mixed with the graphite particles at a mass ratio of 1%, and the petroleum pitch was adhered to the surface of the graphite particles. Then, it carbonized at 1100 degreeC by inert atmosphere. BET specific surface area is 2.6 m 2 / g, d002 is 0.3361 nm, LC is 59 nm, 10% particle diameter (D10) is 2.3 μm, 50% particle diameter (D50) is 5.7 μm, Carbon-coated graphite particles having a 90% particle diameter (D90) of 11.8 μm and I D / I G (R value) of 0.77 were obtained.
0.375 g of Si fine particles and 1.125 g of carbon-coated graphite particles C were taken and mixed in a mortar to obtain a negative electrode material in which Si fine particles and graphite particles were combined.
（負極の製造）
　上記水性エマルジョンにカルボキシメチルセルロース（ダイセル社製、品番：１３８０）を、固形分質量比が１：１となるように加え、混合してなるバインダー混合物を用意した。導電助剤としてＴＩＭＣＡＬ製カーボンブラック（ＳＵＰＥＲ　Ｃ４５）を用意した。前記の負極材１００質量部、バインダー混合物１００質量部、及び導電助剤８５．７質量部を混ぜ合わせ、これに粘度調整のための水を適量加え、自転・公転ミキサー（シンキー社製）にて混練しリチウムイオン電池負極用スラリーを得た。
　得られたリチウムイオン電池負極用スラリーを、負極合材層の厚さが１２０μｍとなるよう銅箔上に塗布した。これを７０℃で３時間乾燥させた。得られたシートから直径１６ｍｍのシート片を打ち抜き、前川試験機製作所製ＰＯＷＥＲ　ＳＡＭＰＬＥ　ＨＹＤＲＡＵＬＩＣ　ＰＲＥＳＳ/ＢＲＥ－３にて１．５ｔｏｎ／ｃｍ２でプレスし、負極を得た。
プレス後の負極に転写はなかった。 (Manufacture of negative electrode)
A binder mixture was prepared by adding carboxymethyl cellulose (manufactured by Daicel, product number: 1380) to the aqueous emulsion so that the solid mass ratio was 1: 1, and mixing them. TIMCAL carbon black (SUPER C45) was prepared as a conductive aid. Mix 100 parts by weight of the negative electrode material, 100 parts by weight of the binder mixture, and 85.7 parts by weight of the conductive additive, add an appropriate amount of water for viscosity adjustment, and use a rotating / revolving mixer (made by Shinky Corporation). This was kneaded to obtain a slurry for a lithium ion battery negative electrode.
The obtained slurry for a lithium ion battery negative electrode was applied on a copper foil such that the negative electrode mixture layer had a thickness of 120 μm. This was dried at 70 ° C. for 3 hours. A sheet piece having a diameter of 16 mm was punched out from the obtained sheet, and pressed at 1.5 ton / cm 2 with a POWER SAMPLE HYDRAULIC PRESS / BRE-3 manufactured by Maekawa Tester, Ltd., to obtain a negative electrode.
There was no transfer on the negative electrode after pressing.
（評価用電池の作製）
　露点－８０℃以下の乾燥アルゴンガス雰囲気に保ったグローブボックス内で下記の操作を実施した。
　２３２０型コインセル（直径２３ｍｍ、厚み２．０ｍｍ）を用意した。
　厚み０．１ｍｍのリチウム箔から直径２０ｍｍの箔片を打ち抜いた。これを正極とした。正極をＳＵＳ製スペーサーにポンチで軽く圧着させた。これをコインセルキャップに入れた。次に電解液をコインセルに注入した。その後、セパレータ（セルガード社製、品番：２５００）及び負極をこの順で載せ、コインセルケースをコインセルキャップとかしめて密封し、評価用リチウムイオン電池を得た。
　なお、電解液は、エチレンカーボネート、メチルエチルカーボネート、及びジエチルカーボネートが体積比で３：５：２の割合で混合された溶媒に電解質ＬｉＰＦ６を１ｍｏｌ／Ｌの濃度で溶解させて得られた液である。 (Production of evaluation battery)
The following operation was carried out in a glove box kept in a dry argon gas atmosphere having a dew point of -80 ° C or lower.
A 2320 type coin cell (diameter 23 mm, thickness 2.0 mm) was prepared.
A foil piece having a diameter of 20 mm was punched from a lithium foil having a thickness of 0.1 mm. This was used as a positive electrode. The positive electrode was lightly pressure-bonded to a SUS spacer with a punch. This was put in a coin cell cap. Next, an electrolytic solution was injected into the coin cell. Thereafter, a separator (manufactured by Celgard, product number: 2500) and a negative electrode were placed in this order, and the coin cell case was crimped and sealed with a coin cell cap to obtain a lithium ion battery for evaluation.
The electrolytic solution was obtained by dissolving electrolyte LiPF 6 at a concentration of 1 mol / L in a solvent in which ethylene carbonate, methyl ethyl carbonate, and diethyl carbonate were mixed at a volume ratio of 3: 5: 2. It is.
（充放電試験）
　評価用リチウムイオン電池に、レストポテンシャルから２５ｍＶまでを８０ｍＡ／ｇで定電流充電した。次いで８０ｍＡ／ｇで定電流放電を行い、１．５Ｖでカットオフした。
　この充放電操作を１サイクルとして５０サイクル行った。１サイクル目の充電容量（初期充電容量）、１サイクル目の放電容量（初期放電容量）、２サイクル目の放電量、及び５０サイクル目の放電容量を測定した。それらの結果を表１に示す。
　表１中、初期効率は初期充電容量に対する初期放電容量の割合であり、放電量維持率は２回目放電容量に対する５０サイクル目の放電容量の割合である。
　また、サイクル特性を図１に示す。 (Charge / discharge test)
The lithium ion battery for evaluation was charged at a constant current of 80 mA / g from rest potential to 25 mV. Subsequently, constant current discharge was performed at 80 mA / g and cut off at 1.5 V.
This charge / discharge operation was performed as 50 cycles for 50 cycles. The charge capacity at the first cycle (initial charge capacity), the discharge capacity at the first cycle (initial discharge capacity), the discharge amount at the second cycle, and the discharge capacity at the 50th cycle were measured. The results are shown in Table 1.
In Table 1, the initial efficiency is the ratio of the initial discharge capacity to the initial charge capacity, and the discharge amount maintenance ratio is the ratio of the discharge capacity at the 50th cycle to the second discharge capacity.
The cycle characteristics are shown in FIG.
　水性エマルジョンの合成において、スチレン２５０部及びアクリル酸２－エチルヘキシル２２０部を、スチレン３２０部及びアクリル酸２－エチルヘキシル１５０部に変えた以外は実施例１記載の水性エマルジョンの合成と同様な操作を行った。得られた水性エマルジョンの不揮発分は４４．９％、粘度２９００ｍＰａ・ｓ、ｐＨ６．５であり、重合体Ｂの酸価は１８．９５であった。また、Ｓｉ－黒鉛複合化負極材の調製、負極の製造、評価用電池の作製、各種評価は、実施例１と同様に行った。その結果を表１に示す。 In the synthesis of the aqueous emulsion, the same operation as in the synthesis of the aqueous emulsion described in Example 1 was performed except that 250 parts of styrene and 220 parts of 2-ethylhexyl acrylate were changed to 320 parts of styrene and 150 parts of 2-ethylhexyl acrylate. It was. The obtained aqueous emulsion had a nonvolatile content of 44.9%, a viscosity of 2900 mPa · s, a pH of 6.5, and the acid value of the polymer B was 18.95. The preparation of the Si-graphite composite negative electrode material, the production of the negative electrode, the production of the evaluation battery, and various evaluations were performed in the same manner as in Example 1. The results are shown in Table 1.
（比較例１）
　実施例１において水性エマルジョンをＳＢＲ（日本ゼオン社製、品番：ＢＭ４００Ｂ）とした以外は実施例１と同様にして負極を製造し、評価用電池を作製して充放電試験を行った。その結果を表１及び図１に示す。プレス後、負極シートがプレス板に付着しており、負極合材層がわずかに転写していた。 (Comparative Example 1)
A negative electrode was produced in the same manner as in Example 1 except that the aqueous emulsion was changed to SBR (manufactured by Zeon Corporation, product number: BM400B) in Example 1, and an evaluation battery was produced and a charge / discharge test was performed. The results are shown in Table 1 and FIG. After pressing, the negative electrode sheet adhered to the press plate, and the negative electrode mixture layer was slightly transferred.
（比較例２）
　水性エマルジョンの合成において、スチレン２５０部及びアクリル酸２－エチルヘキシル２２０部を、アクリル酸２－エチルヘキシル４７０部に変えた以外は実施例１記載の水性エマルジョンの合成と同様な操作を行った。得られた水性エマルジョンの不揮発分は４４．８％、粘度２８００ｍＰａ・ｓ、ｐＨ６．４であり、重合体Ｂの酸価は１８．９５であった。また、Ｓｉ－黒鉛複合化負極材の調製、負極の製造、評価用電池の作製、各種評価は、実施例１と同様に行った。その結果を表１に示す。 (Comparative Example 2)
In the synthesis of the aqueous emulsion, the same operation as in the synthesis of the aqueous emulsion described in Example 1 was performed except that 250 parts of styrene and 220 parts of 2-ethylhexyl acrylate were changed to 470 parts of 2-ethylhexyl acrylate. The obtained aqueous emulsion had a non-volatile content of 44.8%, a viscosity of 2800 mPa · s, a pH of 6.4, and the acid value of the polymer B was 18.95. The preparation of the Si-graphite composite negative electrode material, the production of the negative electrode, the production of the evaluation battery, and various evaluations were performed in the same manner as in Example 1. The results are shown in Table 1.
（比較例３）
　水性エマルジョンの合成において、アクリル酸１５部を、アクリル酸非使用に変えた以外は実施例１の水性エマルジョンの合成と同様な操作を行った。得られた不揮発分は４５．１％、粘度８５０ｍＰａ・ｓ、ｐＨ７．４であった。また、Ｓｉ－黒鉛複合化負極材の合成、負極の製造、評価用電池の作製、各種評価は、実施例１と同様に行った。その結果を表１に示す。 (Comparative Example 3)
In the synthesis of the aqueous emulsion, the same operation as in the synthesis of the aqueous emulsion of Example 1 was performed except that 15 parts of acrylic acid was changed to not using acrylic acid. The obtained non-volatile content was 45.1%, the viscosity was 850 mPa · s, and the pH was 7.4. The synthesis of the Si-graphite composite negative electrode material, the production of the negative electrode, the production of an evaluation battery, and various evaluations were performed in the same manner as in Example 1. The results are shown in Table 1.
Figure JPOXMLDOC01-appb-T000005
Figure JPOXMLDOC01-appb-T000005
　表１に示す通り、実施例１及び実施例２におけるバインダーは合金系負極に対しても良好な結着性を示す。また、実施例１及び実施例２におけるバインダーを使用した評価用電池は初期充放電量及び初期効率とも高い値を示し、かつ５０サイクル目におけるサイクル特性も優れていることが明らかである。 As shown in Table 1, the binders in Examples 1 and 2 also show good binding properties with respect to the alloy-based negative electrode. In addition, it is apparent that the evaluation batteries using the binders in Example 1 and Example 2 have high initial charge / discharge amounts and high initial efficiency, and excellent cycle characteristics at the 50th cycle.

Claims (10)

  1. 　Ｓｉ、Ｓｎ、Ｇｅ及びＩｎからなる群から選ばれるうちの少なくとも一つの元素を含む粒子Ａを活物質として含むリチウムイオン電池用負極材、
    　スチレン、エチレン性不飽和カルボン酸エステル、エチレン性不飽和カルボン酸、及び少なくとも一つのエチレン性不飽和基を有する架橋剤、を必須成分として含有するエチレン性不飽和単量体を重合して得られる重合体Ｂを含むバインダー、及び、
    　水を含む分散媒、を含むスラリー。     A negative electrode material for a lithium ion battery comprising, as an active material, particles A containing at least one element selected from the group consisting of Si, Sn, Ge, and In;
    Obtained by polymerizing an ethylenically unsaturated monomer containing styrene, an ethylenically unsaturated carboxylic acid ester, an ethylenically unsaturated carboxylic acid, and a crosslinking agent having at least one ethylenically unsaturated group as essential components A binder comprising polymer B, and
    A slurry containing a dispersion medium containing water.
  2. 　前記重合体Ｂの酸価が６～１００であることを特徴とする請求項１に記載のスラリー。 The slurry according to claim 1, wherein the acid value of the polymer B is 6 to 100.
  3. 　前記エチレン性不飽和単量体中、スチレンの含有量が３０～７０質量％である、請求項１及び２のいずれか１項に記載のスラリー。 The slurry according to any one of claims 1 and 2, wherein the ethylenically unsaturated monomer has a styrene content of 30 to 70 mass%.
  4. 　前記エチレン性不飽和単量体中、前記架橋剤の含有量が０．１～５質量％である、請求項１乃至３のいずれか１項に記載のスラリー。 The slurry according to any one of claims 1 to 3, wherein the content of the crosslinking agent in the ethylenically unsaturated monomer is 0.1 to 5% by mass.
  5. 　前記リチウムイオン電池用負極材が、炭素粒子Ｃをさらに含む、請求項１乃至４のいずれか１項に記載のスラリー。 The slurry according to any one of claims 1 to 4, wherein the negative electrode material for a lithium ion battery further contains carbon particles C.
  6. 　前記粒子Ａの１００質量部に対し、前記炭素粒子Ｃを２５０～２０００質量部含む、請求項５に記載のスラリー。 The slurry according to claim 5, comprising 250 to 2000 parts by mass of the carbon particles C with respect to 100 parts by mass of the particles A.
  7. 　Ｓｉ、Ｓｎ、Ｇｅ及びＩｎからなる群から選ばれるうちの少なくとも一つの元素を含む粒子Ａを活物質として含むリチウムイオン電池用負極材、及び、
    　スチレン、エチレン性不飽和カルボン酸エステル、エチレン性不飽和カルボン酸、及び少なくとも一つのエチレン性不飽和基を有する架橋剤、を必須成分として含有するエチレン性不飽和単量体を重合して得られる重合体Ｂを含むバインダー、を含むリチウムイオン電池用負極。     A negative electrode material for a lithium ion battery containing, as an active material, particles A containing at least one element selected from the group consisting of Si, Sn, Ge, and In; and
    Obtained by polymerizing an ethylenically unsaturated monomer containing styrene, an ethylenically unsaturated carboxylic acid ester, an ethylenically unsaturated carboxylic acid, and a crosslinking agent having at least one ethylenically unsaturated group as essential components A negative electrode for a lithium ion battery, comprising a binder containing the polymer B.
  8. 　請求項７に記載のリチウムイオン電池用負極を用いて得られるリチウムイオン電池。 A lithium ion battery obtained using the negative electrode for a lithium ion battery according to claim 7.
  9. 　Ｓｉ、Ｓｎ、Ｇｅ及びＩｎからなる群から選ばれるうちの少なくとも一つの元素を含む粒子Ａを活物質として含むリチウムイオン電池用負極材と、
    　スチレン、エチレン性不飽和カルボン酸エステル、エチレン性不飽和カルボン酸、及び少なくとも一つのエチレン性不飽和基を有する架橋剤、を必須成分として含有するエチレン性不飽和単量体を界面活性剤の存在下、重合して得られる重合体Ｂを含む水性エマルジョンとを混合する工程を含む、スラリーの製造方法。     A negative electrode material for a lithium ion battery containing, as an active material, particles A containing at least one element selected from the group consisting of Si, Sn, Ge, and In;
    Presence of surfactant with ethylenically unsaturated monomer containing styrene, ethylenically unsaturated carboxylic acid ester, ethylenically unsaturated carboxylic acid, and crosslinking agent having at least one ethylenically unsaturated group as essential components The manufacturing method of a slurry including the process of mixing below with the aqueous emulsion containing the polymer B obtained by superposition | polymerization.
  10. 　集電体上に、請求項１乃至６のいずれか１項に記載のスラリーを塗布する工程を含むリチウムイオン電池用負極の製造方法。 The manufacturing method of the negative electrode for lithium ion batteries including the process of apply | coating the slurry of any one of Claims 1 thru | or 6 on a collector.
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