WO2014128844A1 - Lithium ion secondary battery - Google Patents

Lithium ion secondary battery Download PDF

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Publication number
WO2014128844A1
WO2014128844A1 PCT/JP2013/054074 JP2013054074W WO2014128844A1 WO 2014128844 A1 WO2014128844 A1 WO 2014128844A1 JP 2013054074 W JP2013054074 W JP 2013054074W WO 2014128844 A1 WO2014128844 A1 WO 2014128844A1
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Prior art keywords
negative electrode
current collector
active material
lithium ion
ion secondary
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PCT/JP2013/054074
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French (fr)
Japanese (ja)
Inventor
賢匠 星
登志雄 阿部
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株式会社 日立製作所
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Priority to PCT/JP2013/054074 priority Critical patent/WO2014128844A1/en
Publication of WO2014128844A1 publication Critical patent/WO2014128844A1/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
    • H01M4/64—Carriers or collectors
    • H01M4/70—Carriers or collectors characterised by shape or form
    • 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
    • H01M4/131—Electrodes based on mixed oxides or hydroxides, or on mixtures of oxides or hydroxides, e.g. LiCoOx
    • 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
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • 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
    • H01M4/64—Carriers or collectors
    • H01M4/70—Carriers or collectors characterised by shape or form
    • H01M4/76—Containers for holding the active material, e.g. tubes, capsules
    • H01M4/762—Porous or perforated metallic containers
    • 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 negative electrode for a lithium ion secondary battery, in particular to a negative electrode.
  • lithium ion secondary batteries In recent years, development for lithium ion secondary batteries has been actively promoted. Graphite is generally used as a negative electrode active material of a lithium ion secondary battery. However, in recent years, with the increase in the cruising distance of electric vehicles and the multifunctionalization of portable terminals, lithium ion secondary batteries are required to have higher capacity. Therefore, as a method of increasing the capacity of lithium ion secondary batteries, studies have been made to increase the capacity of the negative electrode active material, that is, metal-based high-capacity anodes represented by Si and Sn. It is known that the material has a large volume change due to charge and discharge, cracking of the active material and peeling from the current collector occur, and the cycle characteristics are degraded.
  • the negative electrode active material that is, metal-based high-capacity anodes represented by Si and Sn. It is known that the material has a large volume change due to charge and discharge, cracking of the active material and peeling from the current collector occur, and the cycle characteristics are degraded.
  • Patent Document 2 proposes an active material layer composed of a Si-based material on a current collector and the active material in Patent Document 2 in which a porous copper foil having a three-dimensional network structure and an electrode using a Si-based active material are proposed. A method has been proposed to coat the layer with a material having a low ability to form a lithium compound.
  • JP 2011-134521 A Japanese Patent Application Laid-Open No. 2004-228059
  • the active material including the Si phase is coated by a method such as plating before or after the step of forming the electrode on the electrode.
  • a method such as plating before or after the step of forming the electrode on the electrode.
  • the present invention provides a lithium ion secondary battery having excellent life characteristics.
  • the negative electrode includes a current collector and a negative electrode active material capable of inserting and extracting lithium ions, and the current collector is a lamination direction of the positive electrode and the negative electrode. And a current collector hole penetrating in a direction parallel to the electrode, the negative electrode active material is provided in the current collector hole, and the negative electrode active material is any one of Si, SiO, Al, and Sn. Or a combination of lithium ion secondary batteries.
  • FIG. 1 shows an embodiment of the current collector of the present invention
  • FIG. 1 shows an embodiment of the current collector of the present invention
  • process is included in the term if the intended function of the process is achieved, even if it can not be clearly distinguished from other processes, not only the independent process. .
  • FIG. 1 is a view schematically showing an internal structure of a battery according to an embodiment of the present invention.
  • the 1 includes a positive electrode 10, a separator 11, a negative electrode 12, a battery case (ie, battery can) 13, a positive current collection tab 14, a negative current collection tab 15, an inner lid 16,
  • the internal pressure release valve 17, the gasket 18, a positive temperature coefficient (PTC) resistance element 19, a battery cover 20, and an axial center 21 are provided.
  • the battery lid 20 is an integrated component including the inner lid 16, the internal pressure release valve 17, the gasket 18, and the PTC resistance element 19. Further, the positive electrode 10, the separator 11 and the negative electrode 12 are wound around the axial center 21.
  • the separator 11 is inserted between the positive electrode 10 and the negative electrode 12, and an electrode group wound around the axial center 21 is produced.
  • the shaft 21 any known one can be used as long as it can support the positive electrode 10, the separator 11 and the negative electrode 12.
  • the electrode group may be formed into various shapes, such as one obtained by laminating strip electrodes, or one obtained by winding the positive electrode 10 and the negative electrode 12 into an arbitrary shape such as flat.
  • the shape of the battery case 13 may be a cylindrical shape, a flat oval shape, a flat oval shape, a square shape, or the like, in accordance with the shape of the electrode group.
  • the material of the battery case 13 is selected from materials having corrosion resistance to the non-aqueous electrolyte, such as aluminum, stainless steel, nickel plated steel, and the like. Moreover, when the battery case 13 is electrically connected to the positive electrode 10 or the negative electrode 12, deterioration of the material due to corrosion of the battery case 13 or alloying with lithium ions does not occur in the portion in contact with the non-aqueous electrolyte. Thus, the material of the battery case 13 is selected.
  • the electrode group is housed in the battery case 13, the negative electrode current collection tab 15 is connected to the inner wall of the battery case 13, and the positive electrode current collection tab 14 is connected to the bottom surface of the battery cover 20.
  • the electrolyte is injected into the battery container interior 13 before sealing the battery.
  • a method of injecting the electrolytic solution there is a method of adding directly to the electrode group in a state in which the battery cover 20 is released, or a method of adding from an injection port provided on the battery cover 20.
  • the battery cover 20 is brought into close contact with the battery case 13 to seal the entire battery. If there is an electrolyte inlet, seal it as well.
  • a method of sealing the battery there are known techniques such as welding and caulking.
  • the lithium ion battery according to one embodiment of the present invention can be manufactured, for example, by arranging the following negative electrode and positive electrode as opposed to each other with a separator interposed therebetween, and injecting an electrolyte.
  • the structure of the lithium ion battery according to one embodiment of the present invention is not particularly limited, but usually, the positive electrode and the negative electrode and the separator separating them are wound to form a wound electrode group, or the positive electrode, the negative electrode and the separator It can be stacked to form a stacked electrode group.
  • ⁇ Negative electrode> An example of the negative electrode is shown in FIG.
  • the negative electrode 6 a structure in which the negative electrode active material 4 is embedded in the current collector holes 3 of the current collector 2 (FIG. 1 a) having a plurality of current collector holes 3 can be used. By using such a structure, expansion and contraction of the negative electrode active material accompanying charge and discharge can be suppressed.
  • the current collector 2 is made of a metal that can be a current collector of a lithium ion secondary battery.
  • a metal for example, copper, nickel, titanium, stainless steel or an alloy of these metals can be used.
  • copper or a copper alloy, nickel or a nickel alloy it is preferable to use copper or a copper alloy, nickel or a nickel alloy.
  • projections can be provided on the current collector 2 and can be flattened by a press.
  • the position of the protrusion is not particularly limited, but is preferably around the hole. When processing such as pressing is added as necessary, part or all of the holes may be covered. By sliding the holes by pressing, it is possible to suppress the sliding of the active material.
  • lithium ions move from the negative electrode active material to the positive electrode via the current collector and the separator.
  • the top and bottom of the current collector hole 3 have a through hole.
  • the holes vertically penetrated are parallel to the stacking direction of the current collector 2, the separator 5, and the positive electrode 4.
  • the current collector holes 3 have a limited direction or a limited hole volume. It is difficult to limit the expansion of the negative electrode active material in a current collector having a mesh-like pore in which the pore space extends three-dimensionally. Therefore, it is preferable to limit the direction of the current collector holes 3 to one direction or two directions.
  • FIG.4 An example of the current collector 2 of the present invention is shown in FIG. Moreover, the collector sectional drawing of this example is shown to Fig.4 (a).
  • the current collector 2 of FIG. 3 has a current collector hole 3 penetrating in a direction parallel to the stacking direction of the negative electrode 10 and the positive electrode 4. For this reason, expansion of the negative electrode active material can be suppressed without impeding the movement of lithium ions traveling between the negative electrode active material and the positive electrode active material.
  • the direction of the current collector hole 3 does not necessarily have to be parallel to the stacking direction of the negative electrode 10 and the positive electrode 4, and the hole is angled from the direction parallel to the stacking direction of the negative electrode 10 and the positive electrode 4 (FIG. 4b) Alternatively, holes with these various angles may be aligned (FIG. 4c). In the case of the angled hole, it is preferable from the viewpoint of securing a volume in which the negative electrode active material is embedded.
  • the current collector 2 preferably has no hole in the direction perpendicular to the stacking direction. A porous current collector having no restriction on the direction of pores is considered to be less effective in limiting the expansion of the negative electrode active material.
  • the diameter of the current collector holes 3 is preferably 0.1 to 50 ⁇ m, more preferably 0.5 to 30 ⁇ m, and still more preferably 1 to 20 ⁇ m. When it is larger than 0.1 ⁇ m, the introduction of the active material into the pores and the impregnation of the electrolytic solution become easy, and when smaller than 50 ⁇ m, the expansion relaxation power in the pores is maintained and the excellent cycle characteristics are exhibited.
  • the shape of the current collector holes 3 is not particularly limited, but a shape close to a circle is preferable because it can relax against expansion.
  • the shapes of the inside and the outside of the hole may be different.
  • the porosity is preferably 10 to 80%. If it is smaller than 10%, the amount of active material in the pores is small, and the energy density does not increase. On the other hand, if it is 80% or more, the strength of the copper foil may be reduced.
  • “Sparse” is not limited to the shape of a hole using a scanning microscope etc., and can be distinguished by the area of the hole occupied in 100 ⁇ m square, and 1 ⁇ 10 ⁇ 8 m 2 or less is defined as a sparse portion .
  • FIG. 1 A conceptual view of the current collector 2 filled with the negative electrode active material is shown in FIG.
  • the negative electrode active material is filled in the current collector holes 3.
  • the volume ratio of the negative electrode active material to the volume of the current collector holes 3 is preferably in the range of 5 to 95%. From the viewpoint of the energy density of the lithium ion secondary battery, 10% or more is preferable, and 20% or more is more preferable.
  • Lithium ion conductive glass such as (m and n are natural numbers of 1 to 5), polyethylene oxide (PEO), polypropylene oxide (PPO), and polymer-based solid electrolytes which are copolymers of these.
  • one side or both sides of the current collector 2 may be plated. By plating, the conductivity can be improved and the sliding of the active material can be suppressed.
  • a material to be plated any metal other than a metal that reacts at a negative electrode potential such as Al can be used, and for example, copper, zinc, lead, tin, gold, silver, nickel, and those containing them An alloy or the like can be used. From the viewpoint of cost and safety, Cu or Cu alloy is preferable.
  • the negative electrode active material 7 is not particularly limited as long as it is a metal capable of inserting and extracting lithium ions, but a metal material containing any one of Si, SiO, Al and Sn or an alloy of these metals is preferable. From the viewpoint of ease of processing and capacity, Si and SiO are preferable.
  • the negative electrode active material 7 may be partially or entirely coated as necessary.
  • the method of coating is not particularly limited, and examples thereof include plating and carbon coating by heat treatment of a carbon precursor.
  • the covering material is not particularly limited, and metals, carbonaceous substances, polymers and the like can be used.
  • a method of obtaining low crystalline carbon from a carbon precursor using a wet mixing method, a chemical vapor deposition method, a mechanochemical method or the like can be mentioned.
  • the chemical vapor deposition method and the wet mixing method are preferable in that they are uniform and easy to control the reaction system and can maintain the shape of the metal material capable of absorbing and releasing lithium ions.
  • the carbon material precursor forming carbon is not particularly limited, but in the chemical vapor deposition method, aliphatic hydrocarbons, aromatic hydrocarbons, alicyclic hydrocarbons and the like can be used.
  • the treatment can be carried out with a polymer compound such as a phenol resin or a styrene resin, a carbonizable solid such as pitch, or the like as a solid or as a melt.
  • the heat treatment of the treatment is preferably performed in an inert atmosphere, and nitrogen and argon are suitable as the inert atmosphere.
  • the treatment conditions are not particularly limited, but when using a melt, it is preferable to keep the temperature at about 200 ° C.
  • the temperature condition is preferably 800 ° C. or more, more preferably 850 ° C. or more, and still more preferably 900 ° C. or more.
  • the water-soluble polymer is not particularly limited, and examples thereof include polyvinyl pyrrolidone, polyvinyl alcohol, carboxymethyl cellulose salt, polyacrylic acid, polyacrylic acid salt, polyvinyl sulfonic acid, polyvinyl sulfonic acid salt, poly 4-vinylphenol, poly 4- Vinylphenol salt, polystyrene sulfonic acid, polystyrene sulfonate, polyaniline sulfonic acid, alginic acid, alginate and the like can be mentioned.
  • polyvinyl pyrrolidone polyvinyl alcohol, carboxymethyl cellulose salt, polyacrylate, polyvinyl sulfonate, poly 4-vinylphenol salt, polystyrene sulfonate, and alginate are preferable.
  • salts ammonium salts, potassium salts or sodium salts are preferred.
  • One or more of the above materials may be used as the polymer.
  • the volume average particle diameter of the negative electrode active material is not particularly limited, but is preferably 0.01 ⁇ m to 20 ⁇ m, more preferably 0.05 to 15 ⁇ m, and still more preferably 0.2 to 10 ⁇ m.
  • the volume average particle diameter is 0.01 ⁇ m or more, excellent productivity and handleability are obtained. Below 20 ⁇ m, electrode characteristics such as rate characteristics and life characteristics tend to be improved.
  • the particle size distribution can be measured by dispersing the sample in purified water containing a surfactant and using a laser diffraction type particle size distribution analyzer, and the average particle size is calculated as 50% D.
  • the method for producing such particles is not particularly limited as long as the volume average particle diameter is 0.01 to 20 ⁇ m, and examples thereof include a ball mill, bead mill and the like. From the viewpoint of productivity and handleability, wet grinding using a ball mill or bead mill is preferred.
  • the solvent used in the wet pulverization described above is not particularly limited as long as it does not react with metal particles, and examples thereof include aromatic organic solvents such as toluene, xylene, benzene and methyl naphthalene, N-methyl pyrrolidone and dimethyl formaldehyde And dimethylacetaldehyde.
  • a dispersant When performing the above-mentioned wet pulverization, a dispersant may be used if necessary.
  • the dispersant is not particularly limited as long as it is capable of suppressing the aggregation of the metal particles, is soluble in the above organic solvent, and decomposes and burns off when heated, for example, using a surfactant or the like. be able to.
  • the negative electrode for a lithium ion secondary battery is, for example, a negative electrode material for a lithium ion secondary battery and an organic binder according to an embodiment of the present invention described above, and a solvent, such as a stirrer, a ball mill, a super sand mill, and a pressure kneader
  • a solvent such as a stirrer, a ball mill, a super sand mill, and a pressure kneader
  • the mixture is kneaded by an apparatus to prepare a negative electrode material slurry, which is applied to a current collector to form a negative electrode layer, or a paste-like negative electrode material slurry is formed into a sheet shape, pellet shape, etc. Can be obtained by integrating with the current collector.
  • a method of providing a current collector hole in the current collector a method such as pressing with a pin-and-stamp like stamp (several tens ⁇ m), laser opening (several ⁇ m), ion opening (several nm), etc. It can be used.
  • a step of removing the amount of slurry on the surface of the current collector may be added.
  • the organic binder (hereinafter, also referred to as "binder") is not particularly limited.
  • Ethylenically unsaturated carboxylic acid esters eg, methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, (meth) acrylonitrile, and hydroxyethyl (meth) acrylate, etc.
  • ethylenic (Meth) acrylic copolymers composed of unsaturated carboxylic acids (for example, acrylic acid, methacrylic acid, itaconic acid, fumaric acid, maleic acid etc.); polyvinylidene fluoride, polyethylene oxide, polyepichlorohydrin, polyphosphazene, poly Acrylonitrile, polyimide, polyamide And high molecular weight compounds such as
  • These organic binders may be dispersed or dissolved in water, or dissolved in an organic solvent such as N-methyl-2-pyrrolidone (NMP), depending on their physical properties.
  • NMP N-methyl-2-pyrrolidone
  • the content ratio of the organic binder in the negative electrode active material (metallic active material) of the negative electrode for lithium ion secondary batteries is preferably 0.5 to 20% by mass, and more preferably 0.75 to 10% by mass.
  • the content ratio of the organic binder is 0.5% by mass or more, adhesion is good, and destruction of the negative electrode due to expansion and contraction during charge and discharge can be suppressed. On the other hand, it can suppress that electrode resistance becomes large by being 20 mass% or less.
  • the thickener for adjusting viscosity to the said negative electrode material slurry.
  • the thickener for example, carboxymethylcellulose, methylcellulose, hydroxymethylcellulose, ethylcellulose, polyvinyl alcohol, polyacrylic acid, polyacrylate, oxidized starch, casein, alginic acid, alginate and the like can be used.
  • a conductive support material with the said negative electrode material slurry as needed.
  • the conductive aid include carbon black, graphite, coke, carbon fiber, carbon nanotube, acetylene black, and oxides and nitrides exhibiting conductivity.
  • the amount of the conductive auxiliary material used may be about 0.1 to 20% by mass with respect to the lithium ion secondary battery of the present invention.
  • the method for applying the negative electrode material slurry to the current collector is not particularly limited.
  • metal mask printing method electrostatic coating method, dip coating method, spray coating method, roll coating method, doctor blade method, gravure coating method And known methods such as screen printing.
  • the current collector may be impregnated in the slurry, and then vacuum treatment, ultrasonic treatment, or a combination thereof may be performed.
  • a step of integrating the active material and the current collector can be incorporated. Integration of the negative electrode material slurry molded into a sheet-like, pellet-like shape or the like with the current collector can be performed by a known method such as, for example, a roll, a press, or a combination thereof.
  • the negative electrode layer formed on the current collector and the negative electrode layer integrated with the current collector are preferably heat-treated in accordance with the used organic binder. For example, when using an organic binder having a main skeleton of polyacrylonitrile, it is at 100 to 180 ° C., and when using an organic binder having a polyimide or polyamideimide as a main skeleton, at 150 to 450 ° C. Heat treatment is preferred.
  • heat treatment By this heat treatment, the removal of the solvent and the strengthening of the binder proceed, and the adhesion between particles and between the particles and the current collector can be improved.
  • These heat treatments are preferably performed in an inert atmosphere such as helium, argon or nitrogen, or in a vacuum atmosphere, in order to prevent the oxidation of the current collector during processing.
  • the electrode density can be adjusted by pressure treatment.
  • the electrode density is preferably 1.3 to 1.9 g / cc, more preferably 1.4 to 1.7 g / cc, 1.45 More preferably, it is at or above 1.65 g / cc.
  • adhesion is improved and cycle characteristics are improved.
  • the electrolyte solution permeability to the inside of an electrode can be maintained because it is 1.8 g / cc or less.
  • the slurry having metal particles may be applied directly to the current collector.
  • Polymer, conductive metal, carbonaceous material precursor, and carbonaceous material are dispersed and mixed in the wet-pulverized metal particles, if necessary, and heat treatment is performed after coating, so that the upper and lower penetrated holes are formed. It is possible to produce an electrode in which a current collector capable of inserting and extracting lithium ions is integrated.
  • polystyrene sulfonate polyaniline sulfonic acid, alginic acid, alginate and the like.
  • polyvinyl pyrrolidone polyvinyl alcohol, carboxymethyl cellulose salt, polyacrylate, polyvinyl sulfonate, poly 4-vinylphenol salt, polystyrene sulfonate, and alginate
  • salts ammonium salts, potassium salts or sodium salts can be used.
  • One or more of the above materials may be used as the polymer.
  • the metal having conductivity is not particularly limited as long as it is a metal exhibiting conductivity, but Cu, Ni, stainless steel or an alloy of these may be used.
  • processing can be performed with a polymer compound such as a phenol resin or a styrene resin, a carbonizable solid such as pitch, or the like as a solid or as a melt.
  • a polymer compound such as a phenol resin or a styrene resin, a carbonizable solid such as pitch, or the like as a solid or as a melt.
  • the carbonaceous substance include carbon black, graphite, coke, carbon fiber, carbon nanotube, acetylene black, and oxides and nitrides exhibiting conductivity.
  • a method of dispersion and mixing treatment to be performed after the preparation of the slurry a method using a stirring homogenizer, a bead mill, a ball mill or the like can be used.
  • the heat treatment is preferably performed in an inert atmosphere, and nitrogen and argon are suitable as the inert atmosphere.
  • the treatment conditions are not particularly limited, but when using a melt, it is preferable to keep the temperature at about 200 ° C. for a certain period to volatilize the solvent and then raise the temperature to the target temperature.
  • the temperature condition is preferably 800 ° C. or more, more preferably 850 ° C. or more, and still more preferably 900 ° C. or more. By setting the heat treatment to 800 ° C.
  • the positive electrode is composed of a positive electrode active material, a conductive agent, a binder, and a current collector.
  • a positive electrode active material LiCoO2, LiNiO2, and LiMn2O4 are representative examples.
  • the particle size of the positive electrode active material is usually defined to be equal to or less than the thickness of the mixture layer formed from the positive electrode active material, the conductive agent, and the binder.
  • the powder of the positive electrode active material contains coarse particles having a size equal to or larger than the mixture layer thickness, the coarse particles are removed in advance by sieve classification, air flow classification, etc. to produce particles of the mixed layer thickness or less. preferable.
  • the positive electrode active material is generally oxide-based and has high electrical resistance, a conductive agent made of carbon powder is used to compensate for the electrical conductivity.
  • Positive electrode active material and conductive agent 8 Since both are usually powders, the powders can be mixed with a binder to bond the powders together and simultaneously adhere to the current collector.
  • an aluminum foil having a thickness of 10 to 100 ⁇ m, a perforated aluminum foil having a thickness of 10 to 100 ⁇ m and a hole diameter of 0.1 to 10 mm, an expanded metal, a foam metal plate or the like is used.
  • materials such as stainless steel and titanium are also applicable.
  • any current collector can be used without being limited to the material, shape, manufacturing method and the like.
  • a positive electrode slurry obtained by mixing a positive electrode active material, a conductive agent, a binder, and an organic solvent is attached to a current collector by a doctor blade method, dipping method, spray method or the like, then the organic solvent is dried and added by a roll press. It can be produced by pressure molding.
  • a separator is inserted between the positive electrode and the negative electrode manufactured by the above method to prevent a short circuit between the positive electrode and the negative electrode.
  • the separator it is possible to use a polyolefin-based polymer sheet made of polyethylene, polypropylene or the like, or a two-layer structure in which a polyolefin-based polymer and a fluorine-based polymer sheet represented by polyethylene tetrafluoride are welded. is there.
  • a mixture of ceramics and a binder may be formed in a thin layer on the surface of the separator so that the separator does not shrink when the battery temperature rises.
  • These separators can be used in lithium ion batteries if the pore diameter is 0.01 to 10 ⁇ m and the porosity is 20 to 90% because lithium ions need to be transmitted during charge and discharge of the battery.
  • ⁇ Electrolyte> As a representative example of an electrolytic solution that can be used in one embodiment of the present invention, lithium hexafluorophosphate (LiPF 6) as an electrolyte, or a solvent in which ethylene carbonate is mixed with dimethyl carbonate, diethyl carbonate, or ethyl methyl carbonate, etc.
  • lithium borofluoride LiBF 4
  • the present invention is not limited to the type of solvent and electrolyte, and the mixing ratio of solvents, and other electrolytic solutions can also be used.
  • nonaqueous solvents that can be used in the electrolyte include propylene carbonate, ethylene carbonate, butylene carbonate, vinylene carbonate, ⁇ -butyrolactone, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, 1,2-dimethoxyethane, 2 -Methyltetrahydrofuran, dimethylsulfoxide, 1,3-dioxolane, formamide, dimethylformamide, methyl propionate, ethyl propionate, phosphoric acid triester, trimethoxymethane, dioxolane, diethyl ether, sulfolane, 3-methyl-2-
  • non-aqueous solvents such as oxazolidinone,
  • lithium salts such as imide salts of lithium represented by LiPF 6, LiBF 4, LiClO 4, LiCF 3 SO 3, LiCF 3 CO 2, LiCF 3 CO 2, LiAsF 6, LiSbF 6 or lithium trifluoromethanesulfonimide.
  • a non-aqueous electrolytic solution prepared by dissolving these salts in the above-mentioned solvent can be used as a battery electrolytic solution. If it does not decompose
  • an ion conductive polymer such as polyethylene oxide, polyacrylonitrile, polyvinylidene fluoride, polymethyl methacrylate, polyhexafluoropropylene, polyethylene oxide can be used as the electrolyte.
  • an ion conductive polymer such as polyethylene oxide, polyacrylonitrile, polyvinylidene fluoride, polymethyl methacrylate, polyhexafluoropropylene, polyethylene oxide.
  • ionic liquids can be used.
  • EMI-BF4 1-ethyl-3-methylimidazolium tetrafluoroborate
  • LiTFSI lithium salt LiN
  • triglyme and tetraglyme a mixed complex of lithium salt LiN (SO2CF3) 2 (LiTFSI) with triglyme and tetraglyme, cyclic quaternary ammonium type cation (N-methyl-N-)
  • propylpyrrolidinium and imide anions for example, bis (fluorosulfonyl) imide
  • the structure of the lithium ion secondary battery in one embodiment of the present invention is not particularly limited, but generally, a positive electrode and a negative electrode, and a separator provided as needed are wound in a flat spiral shape and wound. It is general to form a plate group, or to stack them in the form of flat plates to form a laminated type electrode plate group, and to enclose these electrode plate groups in an outer package.
  • the lithium ion secondary battery in one embodiment of the present invention is not particularly limited, but is used as a paper type battery, a button type battery, a coin type battery, a laminated type battery, the above cylindrical battery, a square battery or the like.
  • the negative electrode material for a lithium ion secondary battery in one embodiment of the present invention described above is described for a lithium ion secondary battery, general electrochemical devices having a charge and discharge mechanism having insertion and detachment of lithium ions, for example, , Hybrid capacitors and the like.
  • the Si powder with a volume average particle diameter of 25 ⁇ m is crushed to a volume average particle diameter of 2 ⁇ m under the conditions of a grinding pressure of 1.4 MPa and a treatment amount of 1000 kg / h using Nanojet Miser (NJ-100 made by Aisin Technology) Obtained.
  • CMC carboxymethylcellulose
  • SBR styrene butadiene rubber
  • the electrolytic copper foil was subjected to laser processing to make holes having an average diameter of 5 ⁇ m, thereby producing a current collector.
  • the slurry was impregnated with a current collector, and allowed to stand in a vacuum chamber adjusted to ⁇ 0.1 MPa and 4 mg / cm 2 to fabricate an electrode. After impregnation, the electrode was dried in an 80 ° C. stationary dryer for 2 hours. After drying, it was roll-pressed under the condition of linear pressure 1 t / cm and further heat-treated under vacuum at 100 ° C. for 2 hours.
  • the negative electrode for lithium ion secondary batteries was produced using the produced electrode.
  • the obtained negative electrode for a lithium ion secondary battery was punched into 2 cm square and used as a sample for evaluation.
  • the schematic of the cell used for evaluation in FIG. 5 is shown.
  • the concentration of 1 mol / L in a mixed solvent of ethylene carbonate (EC) and ethyl methyl carbonate (EMC) (EC and EMC in volume ratio 1: 2) of LiPF 6 as an electrolyte in a glass cell The solution dissolved in the above was placed, and the separator, the reference electrode (metal lithium), the separator, the copper foil, the evaluation electrode, the separator, the counter electrode (metal lithium), and the separator were stacked and arranged in this order to prepare an evaluation cell.
  • ⁇ Evaluation conditions> The evaluation cell was placed in a thermostat at 25 ° C., and a charge / discharge test was performed.
  • Example 1 Production and evaluation were performed in the same manner as in Example 1 except that Si powder having a volume average particle diameter of 25 ⁇ m was changed to SiO powder having a volume average particle diameter of 5 ⁇ m in Example 1.
  • Si powder purity 99.9%
  • methyl naphthalene and dispersant L-1820 by Kao
  • a bead mill L-1820 by Ashizawa Finetech
  • 200 g of this Si slurry (solid content 30%), 45 g of coal tar pitch (carbonization rate 50%) and 500 g of methyl naphthalene are put into a container made of SUS and stirred, and further circulated by a liquid type ultrasonic homogenizer. Ultrasonic dispersion was performed for 30 minutes to obtain a dispersion.
  • the electrodeposited copper foil (manufactured by Furukawa Electric Co., Ltd.) was laser-processed to form holes having an average diameter of 5 ⁇ m, and a porosity of 70%.
  • the resulting copper foil was impregnated with the prepared slurry, and allowed to stand at -0.1 MPa in a vacuum chamber to adjust to 7 mg / cm 2.
  • methyl naphthalene was evaporated at 200 ° C. using a vacuum furnace, and fired at 900 ° C. for 2 hours at a temperature rising rate of 100 ° C./h to produce a negative electrode for lithium ion secondary battery, except for the following. Similar evaluations were made.
  • Example 3 Production and evaluation were performed in the same manner as in Example 1 except that Si powder having a volume average particle diameter of 25 ⁇ m was changed to SiO powder having a volume average particle diameter of 5 ⁇ m in Example 3.
  • Example 2 It produced and evaluated like Example 1 except having used the electrolytic copper foil which does not have a hole.
  • Example 3 It produced and evaluated like Example 3 except having used the electrolytic copper foil which does not have a hole.

Abstract

A lithium ion secondary battery having a positive electrode and a negative electrode, wherein: the negative electrode comprises a collector and a negative electrode active material that is capable of absorbing and desorbing lithium ions; the collector has collector holes that penetrate the collector in a direction that is parallel to the lamination direction of the positive electrode and the negative electrode; the negative electrode active material is provided within the collector holes; and the negative electrode active material is one element or a combination of two or more elements selected from among Si, SiO, Al and Sn. By providing a collector with collector holes, the orientations of which are limited, and filling the collector holes with a negative electrode active material, expansion and contraction of the negative electrode active material caused by charging and discharging can be restricted.

Description

リチウムイオン二次電池Lithium ion secondary battery
　本発明は、リチウムイオン二次電池用負極、特に負極に関するものである。 The present invention relates to a negative electrode for a lithium ion secondary battery, in particular to a negative electrode.
　近年、リチウムイオン二次電池に対する開発が盛んに進められている。リチウムイオン二次電池の負極活物質には、一般的にグラファイトが使用されている。しかしながら、近年、電気自動車の航続距離の増加や携帯端末の多機能化に伴い、リチウムイオン二次電池には、更なる高容量化が求められている。そこで、リチウムイオン二次電池の高容量化の一手法として、負極活物質の高容量化、つまり、Ｓｉ系、Ｓｎ系に代表される金属系高容量負極の検討がされているが、これらの材料は充放電に伴う体積変化が大きく、活物質の割れや、集電体からの剥離が発生し、サイクル特性が低下することが知られており、この課題を解決する為に例えば特許文献1には、３次元網目構造を有する多孔質銅箔内とＳｉ系活物質を用いた電極が提案され、特許文献２には、集電体上にＳｉ系材料からなる活物質層と該活物質層をリチウム化合物の形成能力の低い材料で被覆する方法が提案されている。 In recent years, development for lithium ion secondary batteries has been actively promoted. Graphite is generally used as a negative electrode active material of a lithium ion secondary battery. However, in recent years, with the increase in the cruising distance of electric vehicles and the multifunctionalization of portable terminals, lithium ion secondary batteries are required to have higher capacity. Therefore, as a method of increasing the capacity of lithium ion secondary batteries, studies have been made to increase the capacity of the negative electrode active material, that is, metal-based high-capacity anodes represented by Si and Sn. It is known that the material has a large volume change due to charge and discharge, cracking of the active material and peeling from the current collector occur, and the cycle characteristics are degraded. In order to solve this problem, for example, Patent Document 2 proposes an active material layer composed of a Si-based material on a current collector and the active material in Patent Document 2 in which a porous copper foil having a three-dimensional network structure and an electrode using a Si-based active material are proposed. A method has been proposed to coat the layer with a material having a low ability to form a lithium compound.
特開２０１１－１３４５２１号公報JP 2011-134521 A 特開２００４－２２８０５９号公報Japanese Patent Application Laid-Open No. 2004-228059
　しかしながら、特許文献１に記載の技術では、製造プロセス上、空隙が３次元網目構造になるため、膨張方向が３次元的に拡がり、電池の設計やサイクル特性などの点で問題がある。 However, in the technology described in Patent Document 1, since the voids have a three-dimensional network structure in the manufacturing process, the expansion direction is three-dimensionally expanded, and there are problems in the design of the battery and cycle characteristics.
　また特許文献２に記載の技術では、活物質の相をＣｕなどの導電性材料で被覆する方法では、Ｓｉ相を含む活物質を電極に形成する工程の前または後にめっきなどの方法で被覆する必要があり、また、被覆膜厚の制御など工業的に手間がかかるという問題がある。 In the technique described in Patent Document 2, in the method of coating the phase of the active material with a conductive material such as Cu, the active material including the Si phase is coated by a method such as plating before or after the step of forming the electrode on the electrode. In addition, there is a problem that it takes time and effort industrially, such as control of coating film thickness.
　本発明は、寿命特性に優れたリチウムイオン二次電池を提供する。 The present invention provides a lithium ion secondary battery having excellent life characteristics.
　上記課題を解決するための本発明の特徴は以下の通りである。 The features of the present invention for solving the above problems are as follows.
　正極と負極を有するリチウムイオン二次電池において、前記負極は集電体と、リチウムイオンを吸蔵・放出可能な負極活物質を有し、前記集電体は、前記正極と前記負極との積層方向に対して平行方向に貫通した集電体孔を有し、前記集電体孔内に前記負極活物質が設けられており、前記負極活物質は、Ｓｉ,ＳｉＯ,Ａｌ,Ｓｎのいずれか一種または複数の組み合わせであるリチウムイオン二次電池。集電体に方向が限られた集電体孔を設け、この集電体孔に負極活物質を充填することで、充放電による負極活物質の膨張収縮を制限することができる。 In a lithium ion secondary battery having a positive electrode and a negative electrode, the negative electrode includes a current collector and a negative electrode active material capable of inserting and extracting lithium ions, and the current collector is a lamination direction of the positive electrode and the negative electrode. And a current collector hole penetrating in a direction parallel to the electrode, the negative electrode active material is provided in the current collector hole, and the negative electrode active material is any one of Si, SiO, Al, and Sn. Or a combination of lithium ion secondary batteries. By providing a current collector hole with a limited direction in the current collector and filling the current collector hole with the negative electrode active material, expansion and contraction of the negative electrode active material due to charge and discharge can be limited.
　本発明により、他の電池特性を低下させることなく寿命特性向上を達成できる。上記した以外の課題、構成及び効果は以下の実施形態の説明により明らかにされる。 According to the present invention, it is possible to achieve the improvement of the life characteristics without deteriorating the other battery characteristics. Problems, configurations, and effects other than those described above will be apparent from the description of the embodiments below.
リチウムイオン二次電池の概略図Schematic of lithium ion secondary battery 本発明の一実施形態を示す図A diagram showing an embodiment of the present invention 本発明集電体の一実施形態を示す図FIG. 1 shows an embodiment of the current collector of the present invention 本発明集電体断面の例を示す図The figure which shows the example of this invention collector cross section リチウムイオン二次電池性能評価の図Figure of lithium ion secondary battery performance evaluation
　以下、図面等を用いて、本発明の実施形態について説明する。以下の説明は本発明の内容の具体例を示すものであり、本発明がこれらの説明に限定されるものではなく、本明細書に開示される技術的思想の範囲内において当業者による様々な変更および修正が可能である。例えば、電池として、円筒型リチウムイオン二次電池を例にとって説明するが、角型電池、ラミネート型電池等、平板上の集電体または平板上の集電体を折り曲げて用いるリチウムイオン二次電池に本発明の思想を適用することが可能である。 Hereinafter, embodiments of the present invention will be described using the drawings and the like. The following description shows specific examples of the content of the present invention, and the present invention is not limited to these descriptions, and various modifications by those skilled in the art can be made within the scope of the technical idea disclosed herein. Changes and modifications are possible. For example, although a cylindrical lithium ion secondary battery is described as an example of a battery, a lithium ion secondary battery such as a rectangular battery, a laminate type battery, or the like is used by bending a current collector on a flat plate or a flat plate on a flat plate It is possible to apply the idea of the present invention to
　また、本発明を説明するための全図において、同一の機能を有するものは、同一の符号を付け、その繰り返しの説明は省略する場合がある。 Moreover, in all the drawings for explaining the present invention, what has the same function may attach the same numerals, and may omit explanation of the repetition.
　本明細書において「工程」との語は、独立した工程だけではなく、他の工程と明確に区別できない場合であってもその工程の所期の作用が達成されれば、本用語に含まれる。 In the present specification, the term "process" is included in the term if the intended function of the process is achieved, even if it can not be clearly distinguished from other processes, not only the independent process. .
　また、明細書において「～」を用いて示された数値範囲は、「～」の前後に記載される数値をそれぞれ最小値及び最大値として含む範囲を示す。
＜リチウムイオン二次電池＞
　本発明の一実施形態におけるリチウムイオン二次電池は、本発明の一実施形態におけるリチウムイオン二次電池用負極を用いてなり、例えば、本発明の一実施形態におけるリチウムイオン二次電池用負極と正極とをセパレータを介して対向して配置し、電解液を注入することにより得ることができる。
図１は、本発明の一実施形態に係る電池の内部構造を模式的に表す図である。図１に示す本発明の一実施形態に係る電池１は、正極１０、セパレータ１１、負極１２、電池容器（即ち電池缶）１３、正極集電タブ１４、負極集電タブ１５、内蓋１６、内圧開放弁１７、ガスケット１８、正温度係数（Positive　temperature　coefficient；ＰＴＣ）抵抗素子１９、及び電池蓋２０、軸心２１から構成される。電池蓋２０は、内蓋１６、内圧開放弁１７、ガスケット１８、及びＰＴＣ抵抗素子１９からなる一体化部品である。また、軸心２１には、正極１０、セパレータ１１及び負極１２が捲回されている。 Further, the numerical range indicated by using “to” in the specification indicates a range including the numerical values described before and after “to” as the minimum value and the maximum value, respectively.
<Lithium ion secondary battery>
The lithium ion secondary battery according to an embodiment of the present invention uses the anode for a lithium ion secondary battery according to an embodiment of the present invention, and for example, an anode for a lithium ion secondary battery according to an embodiment of the present invention It can be obtained by arranging the positive electrode to face the separator via a separator and injecting an electrolytic solution.
FIG. 1 is a view schematically showing an internal structure of a battery according to an embodiment of the present invention. A battery 1 according to an embodiment of the present invention shown in FIG. 1 includes a positive electrode 10, a separator 11, a negative electrode 12, a battery case (ie, battery can) 13, a positive current collection tab 14, a negative current collection tab 15, an inner lid 16, The internal pressure release valve 17, the gasket 18, a positive temperature coefficient (PTC) resistance element 19, a battery cover 20, and an axial center 21 are provided. The battery lid 20 is an integrated component including the inner lid 16, the internal pressure release valve 17, the gasket 18, and the PTC resistance element 19. Further, the positive electrode 10, the separator 11 and the negative electrode 12 are wound around the axial center 21.
　セパレータ１１を正極１０及び負極１２の間に挿入し、軸心２１に捲回した電極群を作製する。軸心２１は、正極１０、セパレータ１１及び負極１２を担持できるものであれば、公知の任意のものを用いることができる。電極群は、図１に示した円筒形状の他に、短冊状電極を積層したもの、又は正極１０と負極１２を扁平状等の任意の形状に捲回したもの等、種々の形状にすることができる。電池容器１３の形状は、電極群の形状に合わせ、円筒形、偏平長円形状、扁平楕円形状、角形等の形状を選択してもよい。 The separator 11 is inserted between the positive electrode 10 and the negative electrode 12, and an electrode group wound around the axial center 21 is produced. As the shaft 21, any known one can be used as long as it can support the positive electrode 10, the separator 11 and the negative electrode 12. In addition to the cylindrical shape shown in FIG. 1, the electrode group may be formed into various shapes, such as one obtained by laminating strip electrodes, or one obtained by winding the positive electrode 10 and the negative electrode 12 into an arbitrary shape such as flat. Can. The shape of the battery case 13 may be a cylindrical shape, a flat oval shape, a flat oval shape, a square shape, or the like, in accordance with the shape of the electrode group.
　電池容器１３の材質は、アルミニウム、ステンレス鋼、ニッケルメッキ鋼製等、非水電解質に対し耐食性のある材料から選択される。また、電池容器１３を正極１０又は負極１２に電気的に接続する場合は、非水電解質と接触している部分において、電池容器１３の腐食やリチウムイオンとの合金化による材料の変質が起こらないように、電池容器１３の材料の選定を行う。 The material of the battery case 13 is selected from materials having corrosion resistance to the non-aqueous electrolyte, such as aluminum, stainless steel, nickel plated steel, and the like. Moreover, when the battery case 13 is electrically connected to the positive electrode 10 or the negative electrode 12, deterioration of the material due to corrosion of the battery case 13 or alloying with lithium ions does not occur in the portion in contact with the non-aqueous electrolyte. Thus, the material of the battery case 13 is selected.
　電池容器１３に電極群を収納し、電池容器１３の内壁に負極集電タブ１５を接続し、電池蓋２０の底面に正極集電タブ１４を接続する。電解液は、電池の密閉の前に電池容器内部１３に注入する。電解液の注入方法は、電池蓋２０を解放した状態にて電極群に直接添加する方法、又は電池蓋２０に設置した注入口から添加する方法がある。 The electrode group is housed in the battery case 13, the negative electrode current collection tab 15 is connected to the inner wall of the battery case 13, and the positive electrode current collection tab 14 is connected to the bottom surface of the battery cover 20. The electrolyte is injected into the battery container interior 13 before sealing the battery. As a method of injecting the electrolytic solution, there is a method of adding directly to the electrode group in a state in which the battery cover 20 is released, or a method of adding from an injection port provided on the battery cover 20.
　その後、電池蓋２０を電池容器１３に密着させ、電池全体を密閉する。電解液の注入口がある場合は、それも密封する。電池を密閉する方法には、溶接、かしめ等公知の技術がある。 Thereafter, the battery cover 20 is brought into close contact with the battery case 13 to seal the entire battery. If there is an electrolyte inlet, seal it as well. As a method of sealing the battery, there are known techniques such as welding and caulking.
　本発明の一実施形態に係るリチウムイオン電池は、例えば、下記のような負極と正極とをセパレータを介して対向して配置し、電解質を注入することによって製造することができる。本発明の一実施形態に係るリチウムイオン電池の構造は特に限定されないが、通常、正極及び負極とそれらを隔てるセパレータとを捲回して捲回式電極群にするか、又は正極、負極及びセパレータを積層させて積層型の電極群とすることができる。 The lithium ion battery according to one embodiment of the present invention can be manufactured, for example, by arranging the following negative electrode and positive electrode as opposed to each other with a separator interposed therebetween, and injecting an electrolyte. The structure of the lithium ion battery according to one embodiment of the present invention is not particularly limited, but usually, the positive electrode and the negative electrode and the separator separating them are wound to form a wound electrode group, or the positive electrode, the negative electrode and the separator It can be stacked to form a stacked electrode group.
　＜負極＞
　図２に負極の例を示す。 <Negative electrode>
An example of the negative electrode is shown in FIG.
　負極６として、複数の集電体孔３を有する集電体２(図１a)の集電体孔３に負極活物質４が埋め込まれた構造を用いることができる。このような構造を用いることで、充放電に伴う負極活物質の膨張・収縮を抑制することができる。 As the negative electrode 6, a structure in which the negative electrode active material 4 is embedded in the current collector holes 3 of the current collector 2 (FIG. 1 a) having a plurality of current collector holes 3 can be used. By using such a structure, expansion and contraction of the negative electrode active material accompanying charge and discharge can be suppressed.
　集電体２は、リチウムイオン二次電池の集電体となり得る金属から構成される。このような金属として例えば、銅、ニッケル、チタン、ステンレス鋼がまたはこれらの金属の合金などを用いることができる。これら金属の中では銅若しくは銅合金、ニッケル若しくはニッケル合金を用いることが好ましい。必要に応じて集電体２に突起物を設けることができ、プレスによって平坦化することもできる。突起物の位置は特に限定されないが、孔周辺にあることが好ましい。プレス等の処理を必要に応じ加えた時に、孔の一部または全体を覆ってもよい。プレスにより孔を閉じることで、活物質の滑落を抑制することができる。 The current collector 2 is made of a metal that can be a current collector of a lithium ion secondary battery. As such a metal, for example, copper, nickel, titanium, stainless steel or an alloy of these metals can be used. Among these metals, it is preferable to use copper or a copper alloy, nickel or a nickel alloy. If necessary, projections can be provided on the current collector 2 and can be flattened by a press. The position of the protrusion is not particularly limited, but is preferably around the hole. When processing such as pressing is added as necessary, part or all of the holes may be covered. By sliding the holes by pressing, it is possible to suppress the sliding of the active material.
　図３に集電体孔３が設けられた集電体２の概念図を示す。 The conceptual diagram of the collector 2 in which the collector hole 3 was provided in FIG. 3 is shown.
　電池２の充放電時にリチウムイオンは負極活物質から集電体からセパレータを介して正極まで移動する。リチウムイオンが効率的に移動するためには、集電体孔３の上下が貫通した孔を有していることが好ましい。ここで上下が貫通した孔とは、集電体２、セパレータ５、正極４の積層方向に対して平行方向である。集電体２、正極４の積層方向に貫通した孔を有することで、リチウムイオンの移動経路を確保することができる。 During charge and discharge of the battery 2, lithium ions move from the negative electrode active material to the positive electrode via the current collector and the separator. In order for lithium ions to move efficiently, it is preferable that the top and bottom of the current collector hole 3 have a through hole. Here, the holes vertically penetrated are parallel to the stacking direction of the current collector 2, the separator 5, and the positive electrode 4. By having the holes penetrating in the stacking direction of the current collector 2 and the positive electrode 4, the migration path of lithium ions can be secured.
　負極活物質の膨張収縮を抑制する観点から、集電体孔３はその方向が限られたもの、または、孔の容積が限られたものであることが好ましい。３次元的に孔の空間が広がる網目状の孔を有するような集電体は負極活物質の膨張を制限することがし難い。したがって、集電体孔３の方向は一方向または二方向程度に制限することが好ましい。 From the viewpoint of suppressing the expansion and contraction of the negative electrode active material, it is preferable that the current collector holes 3 have a limited direction or a limited hole volume. It is difficult to limit the expansion of the negative electrode active material in a current collector having a mesh-like pore in which the pore space extends three-dimensionally. Therefore, it is preferable to limit the direction of the current collector holes 3 to one direction or two directions.
　本発明の集電体２の例を図３に示す。また、本発例の集電体断面図を図４(a)に示す。 An example of the current collector 2 of the present invention is shown in FIG. Moreover, the collector sectional drawing of this example is shown to Fig.4 (a).
　図３の集電体２は、負極１０、正極４の積層方向に対して平行方向に貫通している集電体孔３を有している。このため、負極活物質と正極活物質の間を行き来するリチウムイオンの移動を妨げることなく、且つ、負極活物質の膨張を抑制することができる。 The current collector 2 of FIG. 3 has a current collector hole 3 penetrating in a direction parallel to the stacking direction of the negative electrode 10 and the positive electrode 4. For this reason, expansion of the negative electrode active material can be suppressed without impeding the movement of lithium ions traveling between the negative electrode active material and the positive electrode active material.
　集電体孔３の方向は、必ずしも負極１０と正極４の積層方向に対して平行な方向である必要はなく、負極１０と正極４の積層方向に対して平行な方向から角度をつけた孔(図４ｂ)または、これら様々な角度を有する孔を合わせもっていてもよい(図４ｃ)。角度をつけた孔の場合、負極活物質を埋め込む容積を確保できるという観点から好ましい。また、負極活物質の膨張を制限するためには、集電体２は積層方向に垂直方向に孔を有さないことが好ましい。孔の方向の制限がない多孔質の集電体は、負極活物質の膨張を制限する効果が低いと考えられる。 The direction of the current collector hole 3 does not necessarily have to be parallel to the stacking direction of the negative electrode 10 and the positive electrode 4, and the hole is angled from the direction parallel to the stacking direction of the negative electrode 10 and the positive electrode 4 (FIG. 4b) Alternatively, holes with these various angles may be aligned (FIG. 4c). In the case of the angled hole, it is preferable from the viewpoint of securing a volume in which the negative electrode active material is embedded. Moreover, in order to limit expansion of the negative electrode active material, the current collector 2 preferably has no hole in the direction perpendicular to the stacking direction. A porous current collector having no restriction on the direction of pores is considered to be less effective in limiting the expansion of the negative electrode active material.
　集電体孔３の径は０．１～５０μｍが好ましく、０．５～３０μｍがより好ましく、１～２０μｍがさらに好ましい。０．１μｍより大きいことで、孔への活物質導入や電解液の含浸が容易になり、５０μｍより小さいことで、孔内での膨張緩和力が維持され優れたサイクル特性を示す。 The diameter of the current collector holes 3 is preferably 0.1 to 50 μm, more preferably 0.5 to 30 μm, and still more preferably 1 to 20 μm. When it is larger than 0.1 μm, the introduction of the active material into the pores and the impregnation of the electrolytic solution become easy, and when smaller than 50 μm, the expansion relaxation power in the pores is maintained and the excellent cycle characteristics are exhibited.
　集電体孔３の形状は特に制限されないが、円形に近い形の方が膨張に対し緩和できるため好ましい。孔の内部と外部の形状が異なっていてもよい。 The shape of the current collector holes 3 is not particularly limited, but a shape close to a circle is preferable because it can relax against expansion. The shapes of the inside and the outside of the hole may be different.
　集電体２に占める集電体孔３の容積割合（気孔率）は高い場合、より多くの負極活物質を詰めることができ、リチウムイオン二次電池のエネルギー密度を上げることができる。しかし、集電体孔３の容積割合が高すぎると強度が低下する。気孔率は１０～８０％が好ましい。１０％よりも小さいと、孔内の活物質量が少なく、エネルギー密度が上がらない。一方で、８０％以上では、銅箔の強度が低下する恐れがある。 When the volume ratio (porosity) of the current collector holes 3 in the current collector 2 is high, more negative electrode active materials can be packed, and the energy density of the lithium ion secondary battery can be increased. However, if the volume ratio of the current collector holes 3 is too high, the strength decreases. The porosity is preferably 10 to 80%. If it is smaller than 10%, the amount of active material in the pores is small, and the energy density does not increase. On the other hand, if it is 80% or more, the strength of the copper foil may be reduced.
　また、同一箔状の場合中心部分が疎であると放熱性に優れる電極の作製が可能となる。疎とは、走査型顕微鏡などを使用し、孔の形に限定されず、１００μｍ四方の中に占める孔の面積で見分けることができ、１×１０-8ｍ2以下を疎の部分として規定する。 In addition, in the case of the same foil shape, when the central portion is sparse, it becomes possible to produce an electrode excellent in heat dissipation. “Sparse” is not limited to the shape of a hole using a scanning microscope etc., and can be distinguished by the area of the hole occupied in 100 μm square, and 1 × 10 −8 m 2 or less is defined as a sparse portion .
　負極活物質を充填した集電体２の概念図を図２に示す。負極活物質は集電体孔３内に充填されている。集電体孔３の容積に占める負極活物質の体積割合は５～９５％の範囲が好ましい。リチウムイオン二次電池のエネルギー密度の観点からは１０％以上が好ましく、さらに２０％以上が好ましい。 A conceptual view of the current collector 2 filled with the negative electrode active material is shown in FIG. The negative electrode active material is filled in the current collector holes 3. The volume ratio of the negative electrode active material to the volume of the current collector holes 3 is preferably in the range of 5 to 95%. From the viewpoint of the energy density of the lithium ion secondary battery, 10% or more is preferable, and 20% or more is more preferable.
　上下が貫通した集電体孔３を有していれば、集電体２の片面または両面が、リチウムを吸蔵・放出可能な金属または炭素性物質またはイオン導電性物質などで覆われていてもよい。イオン導電性物質としてはイオン導電性を示す、チオリシコンやＬｉ4ＳｉＯ4－Ｌｉ3ＢＯ3やＬｉＸ－Ｌｉ2Ｏ－ＭｍＯｎ（Ｘ＝Ｉ、Ｂｒ、Ｃｌ）（Ｍ＝Ｂ、Ｓｉ、Ｐなど）（ｍ、ｎは１～５の自然数）などのリチウムイオン導電性ガラス、ポリエチレンオキシド（ＰＥＯ）、ポリプロピレンオキシド（ＰＰＯ）およびこれらの共重合体である高分子系の固体電解質などが挙げられる。 If the top and bottom penetrated the current collector holes 3, even if one side or both sides of the current collector 2 is covered with a metal or a carbonaceous substance or an ion conductive substance capable of inserting and extracting lithium. Good. As an ion conductive substance, it exhibits ion conductivity, such as thiolythicon, Li 4 SiO 4 -Li 3 BO 3 or LiX-Li 2 O-MmOn (X = I, Br, Cl) (M = B, Si, P, etc.) Lithium ion conductive glass such as (m and n are natural numbers of 1 to 5), polyethylene oxide (PEO), polypropylene oxide (PPO), and polymer-based solid electrolytes which are copolymers of these.
　また、集電体２の片面または両面がメッキされていてもよい。メッキをすることにより導電性向上、活物質の滑落を抑制できる効果がある。メッキする材料としては、Ａｌなどの負極電位で反応する金属以外の金属であれば何れも使用することができ、例えば銅、亜鉛、鉛、錫、金、銀、ニッケル、及び、それらを含有する合金等を用いることができる。コスト、安全性の面からＣｕもしくはＣｕ合金などが好ましい。 Also, one side or both sides of the current collector 2 may be plated. By plating, the conductivity can be improved and the sliding of the active material can be suppressed. As a material to be plated, any metal other than a metal that reacts at a negative electrode potential such as Al can be used, and for example, copper, zinc, lead, tin, gold, silver, nickel, and those containing them An alloy or the like can be used. From the viewpoint of cost and safety, Cu or Cu alloy is preferable.
　負極活物質７はリチウムイオンを吸蔵・放出できる金属であれば特に制限はないが、Ｓｉ、ＳｉＯ、Ａｌ、Ｓｎのいずれかの金属物質若しくはこれらの合金から少なくとも１種類を含む金属が好ましい。加工の容易性、容量の観点からＳｉ、ＳｉＯが好ましい。 The negative electrode active material 7 is not particularly limited as long as it is a metal capable of inserting and extracting lithium ions, but a metal material containing any one of Si, SiO, Al and Sn or an alloy of these metals is preferable. From the viewpoint of ease of processing and capacity, Si and SiO are preferable.
　負極活物質７は必要に応じて一部または全体が被覆されていてもよい。被覆の方法は特に制限されないが、メッキや炭素前駆体の熱処理による炭素被覆などが挙げられる。 The negative electrode active material 7 may be partially or entirely coated as necessary. The method of coating is not particularly limited, and examples thereof include plating and carbon coating by heat treatment of a carbon precursor.
　被覆材としては特に限定はなく、金属、炭素性物質、高分子などを用いることができる。 The covering material is not particularly limited, and metals, carbonaceous substances, polymers and the like can be used.
　炭素による被覆をする場合、湿式混合法、化学蒸着法、メカノケミカル法などを用いて、炭素前駆体から低結晶性炭素を得る方法などが挙げられる。均一かつ反応系の制御が容易で、リチウムイオンを吸蔵放出できる金属物質の形状が維持できるといった点から、化学蒸着法及び湿式混合法が好ましい。炭素を形成する炭素性物質前駆体としては、特に制限はないが、化学蒸着法では脂肪族炭化水素、芳香族炭化水素、脂環族炭化水素など用いることができる。具体的には、メタン、エタン、プロパン、トルエン、ベンゼン、キシレン、スチレン、ナフタレン、クレゾール、アントラセン、またはこれらの誘導体等が挙げられる。 また、湿式混合法及びメカノケミカル法では、フェノール樹脂、スチレン樹脂等の高分子化合物、ピッチ等の炭化可能な固形物などを、固形のまま、または溶解物などにして処理を行うことができる。 
処理の熱処理は不活性雰囲気で行うことが好ましく、不活性雰囲気としては、窒素、アルゴンが好適である。処理条件は特に限定されないが、溶解物を用いた場合、２００℃程度で一定時間保持し、溶媒を揮発させ、その後、目的温度まで昇温することが好ましい。温度条件については８００℃以上が好ましく、８５０℃以上がより好ましく、９００℃以上がさらに好ましい。熱処理を８００℃以上とすることで、炭素性物質前駆体の炭素化が充分に進行し、導電性が確保しやすい。 In the case of coating with carbon, a method of obtaining low crystalline carbon from a carbon precursor using a wet mixing method, a chemical vapor deposition method, a mechanochemical method or the like can be mentioned. The chemical vapor deposition method and the wet mixing method are preferable in that they are uniform and easy to control the reaction system and can maintain the shape of the metal material capable of absorbing and releasing lithium ions. The carbon material precursor forming carbon is not particularly limited, but in the chemical vapor deposition method, aliphatic hydrocarbons, aromatic hydrocarbons, alicyclic hydrocarbons and the like can be used. Specific examples thereof include methane, ethane, propane, toluene, benzene, xylene, styrene, naphthalene, cresol, anthracene, and derivatives thereof. Further, in the wet mixing method and the mechanochemical method, the treatment can be carried out with a polymer compound such as a phenol resin or a styrene resin, a carbonizable solid such as pitch, or the like as a solid or as a melt.
The heat treatment of the treatment is preferably performed in an inert atmosphere, and nitrogen and argon are suitable as the inert atmosphere. The treatment conditions are not particularly limited, but when using a melt, it is preferable to keep the temperature at about 200 ° C. for a certain period to volatilize the solvent and then raise the temperature to the target temperature. The temperature condition is preferably 800 ° C. or more, more preferably 850 ° C. or more, and still more preferably 900 ° C. or more. By setting the heat treatment to 800 ° C. or higher, carbonization of the carbonaceous material precursor sufficiently proceeds, and the conductivity is easily secured.
　高分子により負極活物質を被覆する場合、高分子としては、天然高分子、合成高分子等が使用できる。中でも環境負荷やプロセスコストの観点から水溶性高分子が好ましい。水溶性高分子に特に制限はないが、例えば、ポリビニルピロリドン、ポリビニルアルコール、カルボキシメチルセルロース塩、ポリアクリル酸、ポリアクリル酸塩、ポリビニルスルホン酸、ポリビニルスルホン酸塩、ポリ４‐ビニルフェノール、ポリ４‐ビニルフェノール塩、ポリスチレンスルホン酸、ポリスチレンスルホン酸塩、ポリアニリンスルホン酸、アルギン酸、アルギン酸塩などが挙げられる。中でも、ポリビニルピロリドン、ポリビニルアルコール、カルボキシメチルセルロース塩、ポリアクリル酸塩、ポリビニルスルホン酸塩、ポリ４‐ビニルフェノール塩、ポリスチレンスルホン酸塩、アルギン酸塩が好ましい。塩としてはアンモニウム塩、カリウム塩またはナトリウム塩が好ましい。高分子として上記の材料を一種単独または複数種用いても良い。 When the negative electrode active material is coated with a polymer, a natural polymer, a synthetic polymer or the like can be used as the polymer. Among them, water-soluble polymers are preferable from the viewpoint of environmental load and process cost. The water-soluble polymer is not particularly limited, and examples thereof include polyvinyl pyrrolidone, polyvinyl alcohol, carboxymethyl cellulose salt, polyacrylic acid, polyacrylic acid salt, polyvinyl sulfonic acid, polyvinyl sulfonic acid salt, poly 4-vinylphenol, poly 4- Vinylphenol salt, polystyrene sulfonic acid, polystyrene sulfonate, polyaniline sulfonic acid, alginic acid, alginate and the like can be mentioned. Among them, polyvinyl pyrrolidone, polyvinyl alcohol, carboxymethyl cellulose salt, polyacrylate, polyvinyl sulfonate, poly 4-vinylphenol salt, polystyrene sulfonate, and alginate are preferable. As salts, ammonium salts, potassium salts or sodium salts are preferred. One or more of the above materials may be used as the polymer.
　負極活物質の体積平均粒子径は特に制限されないが、０．０１μｍ～２０μｍであることが好ましく、０．０５～１５μｍであることがより好ましく、０．２～１０μｍでることがさらに好ましい。体積平均粒子径が０．０１μｍ以上で良好な生産性と取り扱い性に優れる。２０μｍ以下ではレート特性や寿命特性などの電極特性が向上する傾向がある。粒度分布は界面活性剤を含んだ精製水に試料を分散させ、レーザー回折式粒度分布測定装置で測定することができ、平均粒径は５０％Ｄとして算出される。 The volume average particle diameter of the negative electrode active material is not particularly limited, but is preferably 0.01 μm to 20 μm, more preferably 0.05 to 15 μm, and still more preferably 0.2 to 10 μm. When the volume average particle diameter is 0.01 μm or more, excellent productivity and handleability are obtained. Below 20 μm, electrode characteristics such as rate characteristics and life characteristics tend to be improved. The particle size distribution can be measured by dispersing the sample in purified water containing a surfactant and using a laser diffraction type particle size distribution analyzer, and the average particle size is calculated as 50% D.
　このような粒子の作製方法は体積平均粒子径が０．０１～２０μｍであれば特に限定されないが、例えば、ボールミル、ビーズミル等が挙げられる。生産性や取り扱い性からボールミルまたはビーズミルを用いて湿式粉砕するのが好ましい。 The method for producing such particles is not particularly limited as long as the volume average particle diameter is 0.01 to 20 μm, and examples thereof include a ball mill, bead mill and the like. From the viewpoint of productivity and handleability, wet grinding using a ball mill or bead mill is preferred.
　上記、湿式粉砕する際に使用する溶媒としては金属粒子と反応しないものであれ特に制限はなく、例えば、トルエン、キシレン、ベンゼン、メチルナフタリン等の芳香族系有機溶剤、Ｎ－メチルピロリドン、ジメチルホルムアルデヒド、ジメチルアセトアルデヒドなどが挙げられる。 The solvent used in the wet pulverization described above is not particularly limited as long as it does not react with metal particles, and examples thereof include aromatic organic solvents such as toluene, xylene, benzene and methyl naphthalene, N-methyl pyrrolidone and dimethyl formaldehyde And dimethylacetaldehyde.
　上記、湿式粉砕を行う際、必要に応じ分散剤を使用してもよい。分散剤は、金属粒子の凝集を抑制するものであり、上記の有機溶剤に溶解可能で、加熱した際に分解・焼失するものであれば特に制限はないが、例えば、界面活性剤等を用いることができる。 When performing the above-mentioned wet pulverization, a dispersant may be used if necessary. The dispersant is not particularly limited as long as it is capable of suppressing the aggregation of the metal particles, is soluble in the above organic solvent, and decomposes and burns off when heated, for example, using a surfactant or the like. be able to.
　上記、湿式粉砕で体積平均粒子径を調整し熱処理した後、必要に応じて乾式粉砕を行ってもよい。乾式粉砕は、ジェットミルなどが挙げられる。
＜負極の作製方法＞
　リチウムイオン二次電池用負極は、例えば、既述の本発明の一実施形態におけるリチウムイオン二次電池用負極材及び有機結着材を溶剤とともに攪拌機、ボールミル、スーパーサンドミル、加圧ニーダ等の分散装置により混練して、負極材スラリーを調製し、これを集電体に塗布して負極層を形成する、または、ペースト状の負極材スラリーをシート状、ペレット状等の形状に成形し、これを集電体と一体化することで得ることができる。 After the volume average particle diameter is adjusted by wet pulverization and heat treatment is performed, dry pulverization may be performed if necessary. The dry grinding may, for example, be a jet mill.
<Method of manufacturing negative electrode>
The negative electrode for a lithium ion secondary battery is, for example, a negative electrode material for a lithium ion secondary battery and an organic binder according to an embodiment of the present invention described above, and a solvent, such as a stirrer, a ball mill, a super sand mill, and a pressure kneader The mixture is kneaded by an apparatus to prepare a negative electrode material slurry, which is applied to a current collector to form a negative electrode layer, or a paste-like negative electrode material slurry is formed into a sheet shape, pellet shape, etc. Can be obtained by integrating with the current collector.
　集電体に集電体孔を設ける方法としては、剣山状のスタンプ等によりをプレスする(数十μｍ)、レーザーによる開孔(数μm)、イオンによる開孔(数nm)等の方法を用いることができる。 As a method of providing a current collector hole in the current collector, a method such as pressing with a pin-and-stamp like stamp (several tens μm), laser opening (several μm), ion opening (several nm), etc. It can be used.
　負極材スラリーを集電体に塗布した後、集電体表面のスラリー量を取り除く等の工程を加えてもよい。孔に充填された負極活物質の割合が多いほど負極活物質の膨張を抑える効果は高い。また、リチウムイオン二次電池のエネルギー密度の観点からは、表面に活物質を残すことが好ましい
　有機結着材（以下、「バインダ」ともいう）としては、特に限定されないが、例えば、スチレン‐ブタジエン共重合体；エチレン性不飽和カルボン酸エステル（例えば、メチル（メタ）アクリレート、エチル（メタ）アクリレート、ブチル（メタ）アクリレート、（メタ）アクリロニトリル、及びヒドロキシエチル（メタ）アクリレート等）、及びエチレン性不飽和カルボン酸（例えば、アクリル酸、メタクリル酸、イタコン酸、フマル酸、マレイン酸等）からなる（メタ）アクリル共重合体；ポリフッ化ビニリデン、ポリエチレンオキサイド、ポリエピクロヒドリン、ポリホスファゼン、ポリアクリロニトリル、ポリイミド、ポリアミドイミドなどの高分子化合物が挙げられる。これらの有機結着材は、それぞれの物性によって、水に分散、あるいは溶解したもの、また、Ｎ－メチル‐２－ピロリドン（ＮＭＰ）などの有機溶剤に溶解したものがある。 After the negative electrode material slurry is applied to the current collector, a step of removing the amount of slurry on the surface of the current collector may be added. The larger the proportion of the negative electrode active material filled in the holes, the higher the effect of suppressing the expansion of the negative electrode active material. Further, from the viewpoint of the energy density of the lithium ion secondary battery, it is preferable to leave the active material on the surface. The organic binder (hereinafter, also referred to as "binder") is not particularly limited. Copolymers; Ethylenically unsaturated carboxylic acid esters (eg, methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, (meth) acrylonitrile, and hydroxyethyl (meth) acrylate, etc.), and ethylenic (Meth) acrylic copolymers composed of unsaturated carboxylic acids (for example, acrylic acid, methacrylic acid, itaconic acid, fumaric acid, maleic acid etc.); polyvinylidene fluoride, polyethylene oxide, polyepichlorohydrin, polyphosphazene, poly Acrylonitrile, polyimide, polyamide And high molecular weight compounds such as These organic binders may be dispersed or dissolved in water, or dissolved in an organic solvent such as N-methyl-2-pyrrolidone (NMP), depending on their physical properties.
　リチウムイオン二次電池用負極の負極活物質（金属系活物質）中の有機結着剤の含有比率は、０．５～２０質量％が好ましく、０．７５～１０質量％がより好ましい。有機結着剤の含有比率が０．５質量％以上であることで密着性が良好で、充放電時の膨張・収縮によって負極が破壊されることが抑制される。一方、２０質量％以下であることで電極抵抗が大きくなることを抑制できる。 The content ratio of the organic binder in the negative electrode active material (metallic active material) of the negative electrode for lithium ion secondary batteries is preferably 0.5 to 20% by mass, and more preferably 0.75 to 10% by mass. When the content ratio of the organic binder is 0.5% by mass or more, adhesion is good, and destruction of the negative electrode due to expansion and contraction during charge and discharge can be suppressed. On the other hand, it can suppress that electrode resistance becomes large by being 20 mass% or less.
　また、上記負極材スラリーには、粘度を調製するための増粘剤を添加してもよい。増粘剤としては、例えば、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、ポリアクリル酸塩、酸化スターチ、カゼイン、アルギン酸、アルギン酸塩などを使用することができる。 Moreover, you may add the thickener for adjusting viscosity to the said negative electrode material slurry. As the thickener, for example, carboxymethylcellulose, methylcellulose, hydroxymethylcellulose, ethylcellulose, polyvinyl alcohol, polyacrylic acid, polyacrylate, oxidized starch, casein, alginic acid, alginate and the like can be used.
　また、上記負極材スラリーには、必要に応じて、導電補助材を混合してもよい。導電補助材としては、例えば、カーボンブラック、グラファイト、コークス、カーボンファイバー、カーボンナノチューブ、アセチレンブラック、あるいは導電性を示す酸化物や窒化物等が挙げられる。導電補助材の使用量は、本発明のリチウムイオン二次電池に対して０．１～２０質量％程度とすればよい。 Moreover, you may mix a conductive support material with the said negative electrode material slurry as needed. Examples of the conductive aid include carbon black, graphite, coke, carbon fiber, carbon nanotube, acetylene black, and oxides and nitrides exhibiting conductivity. The amount of the conductive auxiliary material used may be about 0.1 to 20% by mass with respect to the lithium ion secondary battery of the present invention.
　負極材スラリーを集電体に塗布する方法としては、特に限定されないが、例えば、メタルマスク印刷法、静電塗装法、ディップコート法、スプレーコート法、ロールコート法、ドクターブレード法、グラビアコート法、スクリーン印刷法など公知の方法が挙げられる。塗布後は、必要に応じて平板プレス、カレンダーロール等による圧延処理を行うことが好ましい。孔内に負極材を含浸させるために、必要に応じスラリー中に集電体を含浸させた後、真空処理や、超音波処理またはこれらを組み合わせてもよい。 The method for applying the negative electrode material slurry to the current collector is not particularly limited. For example, metal mask printing method, electrostatic coating method, dip coating method, spray coating method, roll coating method, doctor blade method, gravure coating method And known methods such as screen printing. After application, it is preferable to carry out a rolling treatment using a flat plate press, a calender roll, etc. as necessary. In order to impregnate the negative electrode material into the pores, if necessary, the current collector may be impregnated in the slurry, and then vacuum treatment, ultrasonic treatment, or a combination thereof may be performed.
　活物質と集電体を一体化させる工程を組み込むことができる。シート状、ペレット状等の形状に成型された負極材スラリーと集電体との一体化は、例えば、ロール、プレス、もしくはこれらの組み合わせ等、公知の方法により行うことができる。 
　集電体上に形成された負極層及び集電体と一体化した負極層は、用いた有機結着剤に応じて熱処理することが好ましい。例えば、ポリアクリルニトリルを主骨格とした有機結着剤を用いた場合には１００～１８０℃で、ポリイミド、ポリアミドイミドを主骨格とした有機結着剤を用いた場合には１５０～４５０℃で熱処理することが好ましい。 
この熱処理により溶媒の除去、バインダの硬化による高強度化が進み、粒子間及び、粒子と集電体間の密着性が向上できる。尚、これらの熱処理は、処理中の集電体の酸化を防ぐため、ヘリウム、アルゴン、窒素等の不活性雰囲気、または、真空雰囲気で行うことが好ましい。 A step of integrating the active material and the current collector can be incorporated. Integration of the negative electrode material slurry molded into a sheet-like, pellet-like shape or the like with the current collector can be performed by a known method such as, for example, a roll, a press, or a combination thereof.
The negative electrode layer formed on the current collector and the negative electrode layer integrated with the current collector are preferably heat-treated in accordance with the used organic binder. For example, when using an organic binder having a main skeleton of polyacrylonitrile, it is at 100 to 180 ° C., and when using an organic binder having a polyimide or polyamideimide as a main skeleton, at 150 to 450 ° C. Heat treatment is preferred.
By this heat treatment, the removal of the solvent and the strengthening of the binder proceed, and the adhesion between particles and between the particles and the current collector can be improved. These heat treatments are preferably performed in an inert atmosphere such as helium, argon or nitrogen, or in a vacuum atmosphere, in order to prevent the oxidation of the current collector during processing.
　また、熱処理する前に、負極はプレス（加圧処理）しておくことが好ましい。加圧処理することで電極密度を調整することができる。本発明のリチウムイオン二次電池用負極材では、電極密度が１．３～１．９ｇ／ｃｃであることが好ましく、１．４～１．７ｇ／ｃｃであることがより好ましく、１．４５～１．６５ｇ／ｃｃであることがさらに好ましい。１．３ｇ／ｃｃ以上であることで、密着性が向上しサイクル特性が向上する。一方で１．８ｇ／ｃｃ以下であることで、電極内部への電解液浸透性が保てる。 Moreover, it is preferable to press (pressurize) the negative electrode before heat treatment. The electrode density can be adjusted by pressure treatment. In the negative electrode material for a lithium ion secondary battery of the present invention, the electrode density is preferably 1.3 to 1.9 g / cc, more preferably 1.4 to 1.7 g / cc, 1.45 More preferably, it is at or above 1.65 g / cc. By being 1.3 g / cc or more, adhesion is improved and cycle characteristics are improved. On the other hand, the electrolyte solution permeability to the inside of an electrode can be maintained because it is 1.8 g / cc or less.
　金属粒子を有するスラリーを集電体に直接、塗布しても構わない。湿式粉砕した金属粒子中に必要に応じ、高分子、導電性を有する金属、炭素性物質前駆体、炭素性物質を分散・混合し、塗布後、熱処理することで、上下が貫通した孔内にリチウムイオンを吸蔵・放出できる集電体が一体化してなる電極の作製が可能である。 The slurry having metal particles may be applied directly to the current collector. Polymer, conductive metal, carbonaceous material precursor, and carbonaceous material are dispersed and mixed in the wet-pulverized metal particles, if necessary, and heat treatment is performed after coating, so that the upper and lower penetrated holes are formed. It is possible to produce an electrode in which a current collector capable of inserting and extracting lithium ions is integrated.
　高分子としては例えば、ポリビニルピロリドン、ポリビニルアルコール、カルボキシメチルセルロース塩、ポリアクリル酸、ポリアクリル酸塩、ポリビニルスルホン酸、ポリビニルスルホン酸塩、ポリ４‐ビニルフェノール、ポリ４‐ビニルフェノール塩、ポリスチレンスルホン酸、ポリスチレンスルホン酸塩、ポリアニリンスルホン酸、アルギン酸、アルギン酸塩などが挙げられる。中でも、ポリビニルピロリドン、ポリビニルアルコール、カルボキシメチルセルロース塩、ポリアクリル酸塩、ポリビニルスルホン酸塩、ポリ４‐ビニルフェノール塩、ポリスチレンスルホン酸塩、アルギン酸塩を用いることができる。塩としてはアンモニウム塩、カリウム塩またはナトリウム塩を用いることができる。高分子として上記の材料を一種単独または複数種用いても良い。 As the polymer, for example, polyvinyl pyrrolidone, polyvinyl alcohol, carboxymethyl cellulose salt, polyacrylic acid, polyacrylate, polyvinyl sulfonic acid, polyvinyl sulfonate, poly 4-vinylphenol, poly 4-vinylphenol salt, polystyrene sulfonic acid Polystyrene sulfonate, polyaniline sulfonic acid, alginic acid, alginate and the like. Among them, polyvinyl pyrrolidone, polyvinyl alcohol, carboxymethyl cellulose salt, polyacrylate, polyvinyl sulfonate, poly 4-vinylphenol salt, polystyrene sulfonate, and alginate can be used. As salts, ammonium salts, potassium salts or sodium salts can be used. One or more of the above materials may be used as the polymer.
　導電性を有する金属には導電性を示す金属であれば特に制限はないが、Ｃｕ、Ｎｉ、ステンレス鋼若しくはこれらの合金などを用いることができる。 The metal having conductivity is not particularly limited as long as it is a metal exhibiting conductivity, but Cu, Ni, stainless steel or an alloy of these may be used.
　炭素性物質前駆体としては、フェノール樹脂、スチレン樹脂等の高分子化合物、ピッチ等の炭化可能な固形物などを、固形のまま、または溶解物などにして処理を行うことができる。 
　炭素性物質としては、例えば、カーボンブラック、グラファイト、コークス、カーボンファイバー、カーボンナノチューブ、アセチレンブラック、あるいは導電性を示す酸化物や窒化物等が挙げられる。 As the carbonaceous material precursor, processing can be performed with a polymer compound such as a phenol resin or a styrene resin, a carbonizable solid such as pitch, or the like as a solid or as a melt.
Examples of the carbonaceous substance include carbon black, graphite, coke, carbon fiber, carbon nanotube, acetylene black, and oxides and nitrides exhibiting conductivity.
　スラリーの調整後に行う分散・混合処理の方法としては、攪拌式のホモジナイザー、ビーズミル、ボールミルなどを用いた方法を用いることができる。 As a method of dispersion and mixing treatment to be performed after the preparation of the slurry, a method using a stirring homogenizer, a bead mill, a ball mill or the like can be used.
　上下が貫通した孔内にリチウムイオンを電気化学的に吸蔵・放出できる金属を有した集電体は熱処理することが好ましい。熱処理は不活性雰囲気で行うことが好ましく、不活性雰囲気としては、窒素、アルゴンが好適である。処理条件は特に限定されないが、溶解物を用いた場合、２００℃程度で一定時間保持し、溶媒を揮発させ、その後、目的温度まで昇温することが好ましい。温度条件については８００℃以上が好ましく、８５０℃以上がより好ましく、９００℃以上がさらに好ましい。熱処理を８００℃以上とすることで、炭素性物質前駆体の炭素化が充分に進行し、導電性が確保しやすい。
＜正極＞ 
　正極は、正極活物質、導電剤、バインダ、及び集電体から構成される。正極活物質を例示すると、ＬｉＣｏＯ２、ＬｉＮｉＯ２、及びＬｉＭｎ２Ｏ４が代表例である。他に、ＬｉＭｎＯ３、ＬｉＭｎ２Ｏ３、ＬｉＭｎＯ２、Ｌｉ４Ｍｎ５Ｏ１２、ＬｉＭｎ２－ｘＭｘＯ２（ただし、Ｍ＝Ｃｏ、Ｎｉ、Ｆｅ、Ｃｒ、Ｚｎ、Ｔｉからなる群から選ばれる少なくとも１種、ｘ＝０．０１～０．２）、Ｌｉ２Ｍｎ３ＭＯ８（ただし、Ｍ＝Ｆｅ、Ｃｏ、Ｎｉ、Ｃｕ、Ｚｎからなる群から選ばれる少なくとも１種）、Ｌｉ１－ｘＡｘＭｎ２Ｏ４（ただし、Ａ＝Ｍｇ、Ｂ、Ａｌ、Ｆｅ、Ｃｏ、Ｎｉ、Ｃｒ、Ｚｎ、Ｃａからなる群から選ばれる少なくとも１種、ｘ＝０．０１～０．１）、ＬｉＮｉ１－ｘＭｘＯ２（ただし、Ｍ＝Ｃｏ、Ｆｅ、Ｇａからなる群から選ばれる少なくとも１種、ｘ＝０．０１～０．２）、ＬｉＦｅＯ２、Ｆｅ２（ＳＯ４）３、ＬｉＣｏ１－ｘＭｘＯ２（ただし、Ｍ＝Ｎｉ、Ｆｅ、Ｍｎからなる群から選ばれる少なくとも１種、ｘ＝０．０１～０．２）、ＬｉＮｉ１－ｘＭｘＯ２（ただし、Ｍ＝Ｍｎ、Ｆｅ、Ｃｏ、Ａｌ、Ｇａ、Ｃａ、Ｍｇからなる群から選ばれる少なくとも１種、ｘ＝０．０１～０．２）、Ｆｅ（ＭｏＯ４）３、ＦｅＦ３、ＬｉＦｅＰＯ４、及びＬｉＭｎＰＯ４等を列挙することができる。 
　正極活物質の粒径は、正極活物質、導電剤、及びバインダから形成される合剤層の厚さ以下になるように通常は規定される。正極活物質の粉末中に合剤層厚さ以上のサイズを有する粗粒がある場合、予めふるい分級や風流分級等により粗粒を除去し、合剤層厚さ以下の粒子を作製することが好ましい。 
　また、正極活物質は、一般に酸化物系であるために電気抵抗が高いので、電気伝導性を補うための炭素粉末からなる導電剤を利用する。正極活物質及び導電剤8 
はともに通常は粉末であるので、粉末にバインダを混合して、粉末同士を結合させると同時に集電体へ接着させることができる。 
　正極の集電体には、厚さが１０～１００μｍのアルミニウム箔、厚さが１０～１００μｍで孔径が０．１～１０ｍｍのアルミニウム製穿孔箔、エキスパンドメタル、又は発泡金属板等が用いられる。アルミニウムの他に、ステンレスやチタン等の材質も適用可能である。本発明では、材質、形状、製造方法等に制限されることなく、任意の集電体を使用することができる。 
　正極活物質、導電剤、バインダ、及び有機溶媒を混合した正極スラリーを、ドクターブレード法、ディッピング法、又はスプレー法等によって集電体へ付着させた後、有機溶媒を乾燥させ、ロールプレスによって加圧成形することにより、作製することができる。また、塗布から乾燥までを複数回行うことにより、複数の合剤層を集電体に積層化させることも可能である。 
＜セパレータ＞ 
　以上の方法で作製した正極と負極との間にセパレータを挿入し、正極及び負極の短絡を防止する。セパレータには、ポリエチレン、ポリプロピレン等からなるポリオレフィン系高分子シート、又はポリオレフィン系高分子と４フッ化ポリエチレンを代表とするフッ素系高分子シートを溶着させた２層構造等を使用することが可能である。電池温度が高くなったときにセパレータが収縮しないように、セパレータの表面にセラミックス及びバインダの混合物を薄層状に形成してもよい。これらのセパレータは、電池の充放電時にリチウムイオンを透過させる必要があるため、一般に細孔径が０．０１～１０μｍ、気孔率が２０～９０％であれば、リチウムイオン電池に使用可能である。 
＜電解質＞ 
　本発明の一実施形態で使用可能な電解液の代表例として、エチレンカーボネートにジメチルカーボネート、ジエチルカーボネート、又はエチルメチルカーボネート等を混合した溶媒に、電解質として六フッ化リン酸リチウム（ＬｉＰＦ６）、又はホウフッ化リチウム（ＬｉＢＦ４）を溶解させた溶液がある。本発明は、溶媒や電解質の種類、溶媒の混合比に制限されることなく、他の電解液も利用可能である。 
　なお、電解液に使用可能な非水溶媒の例としては、プロピレンカーボネート、エチレンカーボネート、ブチレンカーボネート、ビニレンカーボネート、γ－ブチロラクトン、ジメチルカーボネート、ジエチルカーボネート、メチルエチルカーボネート、１、２－ジメトキシエタン、２－メチルテトラヒドロフラン、ジメチルスルフォキシド、１、３－ジオキソラン、ホルムアミド、ジメチルホルムアミド、プロピオン酸メチル、プロピオン酸エチル、リン酸トリエステル、トリメトキシメタン、ジオキソラン、ジエチルエーテル、スルホラン、３－メチル－２－オキサゾリジノン、テトラヒドロフラン、１、２－ジエトキシエタン、クロルエチレンカーボネート、又はクロルプロピレンカーボネート等の非水溶媒がある。本発明の電池に内蔵される正極４又は負極６上で分解しなければ、これ以外の溶媒を用いてもよい。 
　また、電解質の例としては、ＬｉＰＦ６、ＬｉＢＦ４、ＬｉＣｌＯ４、ＬｉＣＦ３ＳＯ３、ＬｉＣＦ３ＣＯ２、ＬｉＡｓＦ６、ＬｉＳｂＦ６、又はリチウムトリフルオロメタンスルホンイミドで代表されるリチウムのイミド塩等、多種類のリチウム塩がある。これらの塩を、上記の溶媒に溶解してできた非水電解液を電池用電解液として使用することができる。本実施形態に係る電池が有する正極４及び負極６上で分解しなければ、これ以外の電解質を用いてもよい。 
　固体高分子電解質（ポリマー電解質）を用いる場合には、ポリエチレンオキシド、ポリアクリロニトリル、ポリフッ化ビニリデン、ポリメタクリル酸メチル、ポリヘキサフルオロプロピレン、ポリエチレンオキサイド等のイオン伝導性ポリマーを電解質に用いることができる。これらの固体高分子電解質を用いた場合、セパレータ５を省略することができる利点がある。 It is preferable to heat-treat a current collector having a metal capable of electrochemically absorbing and desorbing lithium ions in holes which are vertically penetrated. The heat treatment is preferably performed in an inert atmosphere, and nitrogen and argon are suitable as the inert atmosphere. The treatment conditions are not particularly limited, but when using a melt, it is preferable to keep the temperature at about 200 ° C. for a certain period to volatilize the solvent and then raise the temperature to the target temperature. The temperature condition is preferably 800 ° C. or more, more preferably 850 ° C. or more, and still more preferably 900 ° C. or more. By setting the heat treatment to 800 ° C. or higher, carbonization of the carbonaceous material precursor sufficiently proceeds, and the conductivity is easily secured.
<Positive electrode>
The positive electrode is composed of a positive electrode active material, a conductive agent, a binder, and a current collector. When a positive electrode active material is illustrated, LiCoO2, LiNiO2, and LiMn2O4 are representative examples. In addition, LiMnO 3, LiMn 2 O 3, LiMnO 2, Li 4 Mn 5 O 12, LiMn 2 -x M x O 2 (where M = at least one selected from the group consisting of Co, Ni, Fe, Cr, Zn, Ti, x = 0.01 to 0.2) , Li 2 Mn 3 MO 8 (wherein M is at least one selected from the group consisting of Fe, Co, Ni, Cu, and Zn), Li 1-x A x Mn 2 O 4 (where, A = Mg, B, Al, Fe, Co, Ni, Cr, Zn) And Ca, at least one member selected from the group consisting of x, 0.01 to 0.1, LiNi 1-x M x O 2, provided that M is at least one member selected from the group consisting of Co, Fe and Ga, x = 0 01 to 0.2), LiFeO 2, Fe 2 (SO 4) 3, LiCo 1 -xM x O 2 (where M = Ni, Fe, Mn) At least one selected from the group consisting of x = 0.01 to 0.2), LiNi 1 -x M x O 2 (where M = Mn, Fe, Co, Al, Ga, Ca, Mg), x = 0 .01 to 0.2), Fe (MoO4) 3, FeF3, LiFePO4, and LiMnPO4 can be listed.
The particle size of the positive electrode active material is usually defined to be equal to or less than the thickness of the mixture layer formed from the positive electrode active material, the conductive agent, and the binder. When the powder of the positive electrode active material contains coarse particles having a size equal to or larger than the mixture layer thickness, the coarse particles are removed in advance by sieve classification, air flow classification, etc. to produce particles of the mixed layer thickness or less. preferable.
In addition, since the positive electrode active material is generally oxide-based and has high electrical resistance, a conductive agent made of carbon powder is used to compensate for the electrical conductivity. Positive electrode active material and conductive agent 8
Since both are usually powders, the powders can be mixed with a binder to bond the powders together and simultaneously adhere to the current collector.
As the current collector of the positive electrode, an aluminum foil having a thickness of 10 to 100 μm, a perforated aluminum foil having a thickness of 10 to 100 μm and a hole diameter of 0.1 to 10 mm, an expanded metal, a foam metal plate or the like is used. Besides aluminum, materials such as stainless steel and titanium are also applicable. In the present invention, any current collector can be used without being limited to the material, shape, manufacturing method and the like.
A positive electrode slurry obtained by mixing a positive electrode active material, a conductive agent, a binder, and an organic solvent is attached to a current collector by a doctor blade method, dipping method, spray method or the like, then the organic solvent is dried and added by a roll press. It can be produced by pressure molding. Moreover, it is also possible to laminate a plurality of mixture layers on the current collector by performing application to drying a plurality of times.
<Separator>
A separator is inserted between the positive electrode and the negative electrode manufactured by the above method to prevent a short circuit between the positive electrode and the negative electrode. For the separator, it is possible to use a polyolefin-based polymer sheet made of polyethylene, polypropylene or the like, or a two-layer structure in which a polyolefin-based polymer and a fluorine-based polymer sheet represented by polyethylene tetrafluoride are welded. is there. A mixture of ceramics and a binder may be formed in a thin layer on the surface of the separator so that the separator does not shrink when the battery temperature rises. These separators can be used in lithium ion batteries if the pore diameter is 0.01 to 10 μm and the porosity is 20 to 90% because lithium ions need to be transmitted during charge and discharge of the battery.
<Electrolyte>
As a representative example of an electrolytic solution that can be used in one embodiment of the present invention, lithium hexafluorophosphate (LiPF 6) as an electrolyte, or a solvent in which ethylene carbonate is mixed with dimethyl carbonate, diethyl carbonate, or ethyl methyl carbonate, etc. There is a solution in which lithium borofluoride (LiBF 4) is dissolved. The present invention is not limited to the type of solvent and electrolyte, and the mixing ratio of solvents, and other electrolytic solutions can also be used.
Examples of nonaqueous solvents that can be used in the electrolyte include propylene carbonate, ethylene carbonate, butylene carbonate, vinylene carbonate, γ-butyrolactone, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, 1,2-dimethoxyethane, 2 -Methyltetrahydrofuran, dimethylsulfoxide, 1,3-dioxolane, formamide, dimethylformamide, methyl propionate, ethyl propionate, phosphoric acid triester, trimethoxymethane, dioxolane, diethyl ether, sulfolane, 3-methyl-2- There are non-aqueous solvents such as oxazolidinone, tetrahydrofuran, 1,2-diethoxyethane, chloroethylene carbonate, or chloropropylene carbonate. Other solvents may be used as long as they do not decompose on the positive electrode 4 or the negative electrode 6 incorporated in the battery of the present invention.
In addition, examples of the electrolyte include many kinds of lithium salts such as imide salts of lithium represented by LiPF 6, LiBF 4, LiClO 4, LiCF 3 SO 3, LiCF 3 CO 2, LiCF 3 CO 2, LiAsF 6, LiSbF 6 or lithium trifluoromethanesulfonimide. A non-aqueous electrolytic solution prepared by dissolving these salts in the above-mentioned solvent can be used as a battery electrolytic solution. If it does not decompose | disassemble on the positive electrode 4 and the negative electrode 6 which the battery which concerns on this embodiment has, you may use electrolytes other than this.
When a solid polymer electrolyte (polymer electrolyte) is used, an ion conductive polymer such as polyethylene oxide, polyacrylonitrile, polyvinylidene fluoride, polymethyl methacrylate, polyhexafluoropropylene, polyethylene oxide can be used as the electrolyte. When these solid polymer electrolytes are used, there is an advantage that the separator 5 can be omitted.
　さらに、イオン性液体を用いることができる。例えば、１－ｅｔｈｙｌ－３－ｍｅｔｈｙｌｉｍｉｄａｚｏｌｉｕｍ ｔｅｔｒａｆｌｕｏｒｏｂｏｒａｔｅ（ＥＭＩ－ＢＦ４）、リチウム塩ＬｉＮ（ＳＯ２ＣＦ３）２（ＬｉＴＦＳＩ）とトリグライムとテトラグライムとの混合錯体、環状四級アンモニウム系陽イオン（Ｎ－ｍｅｔｈｙｌ－Ｎ－ｐｒｏｐｙｌｐｙｒｒｏｌｉｄｉｎｉｕｍが例示される。）、及びイミド系陰イオン（ｂｉｓ（ｆｌｕｏｒｏｓｕｌｆｏｎｙｌ）ｉｍｉｄｅが例示される。）より、正極及び負極にて分解しない組み合わせを選択して、本実施形態に係る電池に用いることができる。 
　本発明の一実施形態におけるリチウムイオン二次電池の構造は、特に限定されないが、通常、正極及び負極と、必要に応じて設けられたセパレータとを、扁平渦巻状に巻回して巻回方極板群としたり、これらを平板状として積層して積層式極板群としたりし、これら極板群を外装体中に封入した構造とするのが一般的である。 
本発明の一実施形態におけるリチウムイオン二次電池は、特に限定されないが、ペーパー型電池、ボタン型電池、コイン型電池、積層型電池、上記の円筒形電池、角型電池などとして使用される。 In addition, ionic liquids can be used. For example, 1-ethyl-3-methylimidazolium tetrafluoroborate (EMI-BF4), a mixed complex of lithium salt LiN (SO2CF3) 2 (LiTFSI) with triglyme and tetraglyme, cyclic quaternary ammonium type cation (N-methyl-N-) It is possible to select a combination that does not decompose at the positive electrode and the negative electrode from propylpyrrolidinium and imide anions (for example, bis (fluorosulfonyl) imide) and use them in the battery according to the present embodiment. it can.
The structure of the lithium ion secondary battery in one embodiment of the present invention is not particularly limited, but generally, a positive electrode and a negative electrode, and a separator provided as needed are wound in a flat spiral shape and wound. It is general to form a plate group, or to stack them in the form of flat plates to form a laminated type electrode plate group, and to enclose these electrode plate groups in an outer package.
The lithium ion secondary battery in one embodiment of the present invention is not particularly limited, but is used as a paper type battery, a button type battery, a coin type battery, a laminated type battery, the above cylindrical battery, a square battery or the like.
　上述した本発明の一実施形態におけるリチウムイオン二次電池用負極材は、リチウムイオン二次電池用と記載したが、リチウムイオンを挿入脱離することを充放電機構とする電気化学装置全般、例えば、ハイブリッドキャパシタなどにも適用することが可能である。  Although the negative electrode material for a lithium ion secondary battery in one embodiment of the present invention described above is described for a lithium ion secondary battery, general electrochemical devices having a charge and discharge mechanism having insertion and detachment of lithium ions, for example, , Hybrid capacitors and the like.
　以下、本発明を実施例により具体的に説明するが、本発明はこれらの実施例に限定されるものではない。尚、特に断りのない限り、「部」及び「％」は質量基準である。 EXAMPLES Hereinafter, the present invention will be specifically described by way of examples, but the present invention is not limited to these examples. In addition, unless there is particular notice, "part" and "%" are mass references.
　体積平均粒子径２５μｍのＳｉ粉末をナノジェットマイザー（アイシンテクノロジー製　ＮＪ－１００）を用いて、粉砕圧１．４ＭＰａ、処理量１０００ｋｇ／ｈの条件で体積平均粒子径2μｍまで粉砕し、粉砕粉を得た。 The Si powder with a volume average particle diameter of 25 μm is crushed to a volume average particle diameter of 2 μm under the conditions of a grinding pressure of 1.4 MPa and a treatment amount of 1000 kg / h using Nanojet Miser (NJ-100 made by Aisin Technology) Obtained.
　得られた粒子の７５部に対して、バインダとしてカルボキシメチルセルロース（ＣＭＣ）（ダイセル工業製２２００）を５部、スチレンブタジエンゴム（ＳＢＲ）（日本ゼオン製ＢＭ４００Ｂ）を５部、導電性を有する材料として、アセチレンブラック（ＨＳ１００　電気化学工業）を１５部に適宜水を添加し、プラネタリーミキサー（ＰＲＩＭＩＸ製ハイビスミックス　２Ｐ－０３型）にて分散・混合しスラリーを作製した。 5 parts of carboxymethylcellulose (CMC) (2200, manufactured by Daicel Industries, Ltd.) as a binder, 5 parts of styrene butadiene rubber (SBR) (BM400B, manufactured by Nippon Zeon), as a material having conductivity to 75 parts of the obtained particles Then, 15 parts of acetylene black (HS100 Denki Kagaku Kogyo Co., Ltd.) was appropriately added with water, and dispersed and mixed by a planetary mixer (Hibismix 2P-03 type manufactured by PRIMIX) to prepare a slurry.
　電解銅箔を、レーザー加工し平均直径5μｍの孔を開け、集電体を作製した。スラリーに集電体を含浸させ、－０．１ＭＰａ、４ｍｇ／ｃｍ２となるように調整した真空チャンバー内に静置し、電極を作製した。含浸後、この電極を８０℃定置型乾燥機にて２時間乾燥させた。乾燥後、線圧１ｔ／ｃｍの条件でロールプレスし、さらに１００℃２時間の真空で熱処理した。作製した電極を用いてリチウムイオン二次電池用負極を作製した。得られたリチウムイオン二次電池用負極を、２ｃｍ四方に打ち抜き、これを評価用試料として使用した。 The electrolytic copper foil was subjected to laser processing to make holes having an average diameter of 5 μm, thereby producing a current collector. The slurry was impregnated with a current collector, and allowed to stand in a vacuum chamber adjusted to −0.1 MPa and 4 mg / cm 2 to fabricate an electrode. After impregnation, the electrode was dried in an 80 ° C. stationary dryer for 2 hours. After drying, it was roll-pressed under the condition of linear pressure 1 t / cm and further heat-treated under vacuum at 100 ° C. for 2 hours. The negative electrode for lithium ion secondary batteries was produced using the produced electrode. The obtained negative electrode for a lithium ion secondary battery was punched into 2 cm square and used as a sample for evaluation.
　図５に評価に用いたセルの概略図を示す。図５に示すようにガラスセルに電解液としてＬｉＰＦ６をエチレンカーボネート（ＥＣ）及びエチルメチルカーボネート（ＥＭＣ）（ＥＣとＥＭＣは体積比で１：２）の混合溶媒に１ｍｏｌ／Ｌの濃度になるように溶解させた溶液を入れ、セパレータ、参照極（金属リチウム）、セパレータ、銅箔、評価用電極、セパレータ、対極（金属リチウム）、セパレータの順に積層して配置し評価用セルを作製した。
＜評価条件＞
　評価用セルは２５℃の恒温槽に入れ、充放電試験を行った。充電は、２ｍＡの定電流で０Ｖまで充電後、０Ｖの定電圧で電流値が０．２ｍＡになるまで行った。放電は、２ｍＡの定電流で１．５Ｖの電圧値まで行った。
また、サイクル特性は、前記充放電条件にて５０回充放電試験をした後の放電容量を初回の放電容量と比較し、その容量維持率として評価した。
評価結果を表１に示す。 The schematic of the cell used for evaluation in FIG. 5 is shown. As shown in FIG. 5, the concentration of 1 mol / L in a mixed solvent of ethylene carbonate (EC) and ethyl methyl carbonate (EMC) (EC and EMC in volume ratio 1: 2) of LiPF 6 as an electrolyte in a glass cell The solution dissolved in the above was placed, and the separator, the reference electrode (metal lithium), the separator, the copper foil, the evaluation electrode, the separator, the counter electrode (metal lithium), and the separator were stacked and arranged in this order to prepare an evaluation cell.
<Evaluation conditions>
The evaluation cell was placed in a thermostat at 25 ° C., and a charge / discharge test was performed. After charging to 0 V with a constant current of 2 mA, charging was performed until the current value became 0.2 mA with a constant voltage of 0 V. Discharge was performed at a constant current of 2 mA up to a voltage value of 1.5V.
In addition, the cycle characteristics were evaluated as the capacity retention rate by comparing the discharge capacity after the 50 charge and discharge tests under the above-mentioned charge and discharge conditions with the initial discharge capacity.
The evaluation results are shown in Table 1.
　実施例１において体積平均粒子径２５μｍのＳｉ粉末を体積平均粒子径５μｍのＳｉＯ粉末に変更した以外実施例１と同様に作製、評価を行った。 Production and evaluation were performed in the same manner as in Example 1 except that Si powder having a volume average particle diameter of 25 μm was changed to SiO powder having a volume average particle diameter of 5 μm in Example 1.
　体積平均粒子径２５μｍのＳｉ粉末（純度９９．９％）を、メチルナフタレン、分散剤（花王製Ｌ－１８２０）とともに、ビーズミル（アシザワファインテック製ＬＭＺ）で体積平均粒子径０．２μｍまで粉砕してＳｉスラリーを作製した。このＳｉスラリー２００ｇ（固形分３０％）と、コールタールピッチ（炭素化率５０％）４５ｇと、メチルナフタレン５００ｇをＳＵＳ製容器に入れて攪拌し、さらに通液型の超音波ホモジナイザーで循環しながら３０分間、超音波分散処理して分散物を得た。 Si powder (purity 99.9%) with a volume average particle diameter of 25 μm is crushed together with methyl naphthalene and dispersant (L-1820 by Kao) with a bead mill (LMZ manufactured by Ashizawa Finetech) to a volume average particle diameter of 0.2 μm Si slurry was prepared. 200 g of this Si slurry (solid content 30%), 45 g of coal tar pitch (carbonization rate 50%) and 500 g of methyl naphthalene are put into a container made of SUS and stirred, and further circulated by a liquid type ultrasonic homogenizer. Ultrasonic dispersion was performed for 30 minutes to obtain a dispersion.
　電解銅箔（古河電工製）を、レーザー加工し平均直径5μｍの孔を開け、気孔率７０％とした。この銅箔を作製したスラリーに含浸させ、真空チャンバー内に－０．１ＭＰａで静地させ７ｍｇ／ｃｍ２になるように調整した。含浸後、真空炉を用いて２００℃でメチルナフタレンを蒸発させたのち、昇温速度１００℃／ｈで９００℃で２時間焼成しリチウムイオン二次電池用負極作製した以外は、実施例１と同様の評価を行った。 The electrodeposited copper foil (manufactured by Furukawa Electric Co., Ltd.) was laser-processed to form holes having an average diameter of 5 μm, and a porosity of 70%. The resulting copper foil was impregnated with the prepared slurry, and allowed to stand at -0.1 MPa in a vacuum chamber to adjust to 7 mg / cm 2. After impregnation, methyl naphthalene was evaporated at 200 ° C. using a vacuum furnace, and fired at 900 ° C. for 2 hours at a temperature rising rate of 100 ° C./h to produce a negative electrode for lithium ion secondary battery, except for the following. Similar evaluations were made.
実施例３において体積平均粒子径２５μｍのＳｉ粉末を体積平均粒子径５μｍのＳｉＯ粉末に変更した以外実施例１と同様に作製、評価を行った。 Production and evaluation were performed in the same manner as in Example 1 except that Si powder having a volume average particle diameter of 25 μm was changed to SiO powder having a volume average particle diameter of 5 μm in Example 3.
比較例１Comparative Example 1
孔を有しない電解銅箔を用いた以外は実施例１と同様に作製、評価を行った。 It produced and evaluated like Example 1 except having used the electrolytic copper foil which does not have a hole.
比較例２Comparative example 2
孔を有しない電解銅箔を用いた以外は実施例３と同様に作製、評価を行った。
Figure JPOXMLDOC01-appb-T000001
 It produced and evaluated like Example 3 except having used the electrolytic copper foil which does not have a hole.
Figure JPOXMLDOC01-appb-T000001
１：電池
２：集電体
３：集電体孔
４：負極活物質
１０：正極
１１：セパレータ
１２：負極
１３：電池容器
１４：正極集電タブ
１５：負極集電タブ
１６：内蓋
１７：内圧開放弁
１８：ガスケット
１９：正温度係数抵抗素子
２０：電池蓋
２１：軸心 1: Battery 2: Current collector 3: Current collector hole 4: Negative electrode active material 10: Positive electrode 11: Separator 12: Negative electrode 13: Battery container 14: Positive electrode current collection tab 15: Negative electrode current collection tab 16: Inner lid 17: Internal pressure release valve 18: Gasket 19: Positive temperature coefficient resistance element 20: Battery cover 21: Shaft center

Claims (5)

  1. 　正極と負極を有するリチウムイオン二次電池において、
    　前記負極は集電体と、リチウムイオンを吸蔵・放出可能な負極活物質を有し、
    　前記集電体は、前記正極と前記負極との積層方向に対して平行方向に貫通した集電体孔を有し、
    　前記集電体孔内に前記負極活物質が設けられており、
    　前記負極活物質は、Ｓｉ,ＳｉＯ,Ａｌ,Ｓｎのいずれか一種または複数の組み合わせであるリチウムイオン二次電池。     In a lithium ion secondary battery having a positive electrode and a negative electrode,
    The negative electrode includes a current collector and a negative electrode active material capable of inserting and extracting lithium ions,
    The current collector has a current collector hole penetrating in a direction parallel to the stacking direction of the positive electrode and the negative electrode,
    The negative electrode active material is provided in the current collector hole,
    The lithium ion secondary battery, wherein the negative electrode active material is any one or a combination of Si, SiO, Al, and Sn.
  2. 　請求項１または請求項２において、
    　前記集電体の気孔率は８０％以下であるリチウムイオン二次電池。     In claim 1 or claim 2,
    The lithium ion secondary battery in which the porosity of the current collector is 80% or less.
  3. 　請求項１または請求項２において、
    　前記集電体孔の直径は、０．１～５０μｍの範囲であるリチウムイオン二次電池。     In claim 1 or claim 2,
    The diameter of the current collector holes is in the range of 0.1 to 50 μm.
  4. 　請求項１ないし請求項３のいずれかにおいて、
    　前記集電体は、銅、ニッケル、銅を含む合金、ニッケルを含む、合金、またはステンレスのいずれかであるリチウムイオン二次電池。     In any one of claims 1 to 3,
    The lithium ion secondary battery in which the current collector is any of copper, nickel, an alloy containing copper, an alloy containing nickel, an alloy, or stainless steel.
  5. 　請求項１ないし請求項４のいずれかにおいて、
    　前記負極活物質の平均粒子径は、０．０１～２０μmの範囲であるリチウムイオン二次電池負極。     In any one of claims 1 to 4,
    The lithium ion secondary battery negative electrode, wherein the average particle diameter of the negative electrode active material is in the range of 0.01 to 20 μm.
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