WO2020091026A1 - Non-aqueous electrolyte secondary battery - Google Patents

Non-aqueous electrolyte secondary battery Download PDF

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Publication number
WO2020091026A1
WO2020091026A1 PCT/JP2019/042960 JP2019042960W WO2020091026A1 WO 2020091026 A1 WO2020091026 A1 WO 2020091026A1 JP 2019042960 W JP2019042960 W JP 2019042960W WO 2020091026 A1 WO2020091026 A1 WO 2020091026A1
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Prior art keywords
electrolyte secondary
aqueous electrolyte
secondary battery
electrode plate
porous layer
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PCT/JP2019/042960
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French (fr)
Japanese (ja)
Inventor
孝輔 倉金
一郎 有瀬
村上　力
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住友化学株式会社
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Priority to KR1020217015735A priority Critical patent/KR102575331B1/en
Publication of WO2020091026A1 publication Critical patent/WO2020091026A1/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
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/409—Separators, membranes or diaphragms characterised by the material
    • H01M50/443—Particulate material
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/409—Separators, membranes or diaphragms characterised by the material
    • H01M50/446—Composite material consisting of a mixture of organic and inorganic materials
    • 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
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
    • H01M10/0564—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of organic materials only
    • H01M10/0566—Liquid materials
    • 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
    • H01M10/058—Construction or manufacture
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/131—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
    • H01M4/133—Electrodes based on carbonaceous material, e.g. graphite-intercalation compounds or CFx
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/409—Separators, membranes or diaphragms characterised by the material
    • H01M50/411—Organic material
    • H01M50/414—Synthetic resins, e.g. thermoplastics or thermosetting resins
    • H01M50/423—Polyamide resins
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/409—Separators, membranes or diaphragms characterised by the material
    • H01M50/449—Separators, membranes or diaphragms characterised by the material having a layered structure
    • H01M50/451—Separators, membranes or diaphragms characterised by the material having a layered structure comprising layers of only organic material and layers containing inorganic material
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/489—Separators, membranes, diaphragms or spacing elements inside the cells, characterised by their physical properties, e.g. swelling degree, hydrophilicity or shut down properties
    • 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
    • H01M2004/021—Physical characteristics, e.g. porosity, surface area
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M2300/00—Electrolytes
    • H01M2300/0017—Non-aqueous electrolytes
    • H01M2300/0025—Organic electrolyte
    • 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
    • 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
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
    • Y02P70/50—Manufacturing or production processes characterised by the final manufactured product

Definitions

  • the present invention relates to a non-aqueous electrolyte secondary battery.
  • Non-aqueous electrolyte secondary batteries such as lithium secondary batteries are currently widely used as batteries for devices such as personal computers, mobile phones and personal digital assistants.
  • porous base material containing polyolefin as a main component as a separator.
  • the porous base material containing polyolefin as a main component has a shutdown function of closing pores open in the porous base material at about 130 ° C. to 140 ° C. when the battery internal temperature rises due to some trouble.
  • the porous base material containing polyolefin as the main component has low heat resistance, so that it is melted by being exposed to a temperature higher than the temperature at which the shutdown function operates, resulting in a short circuit inside the battery and ignition of the battery. Or there was a risk of an explosion. Therefore, for the purpose of improving the heat resistance of the porous base material, a separator in which a porous layer containing a filler and a resin is laminated on at least one surface of the porous base material is being developed.
  • Patent Document 1 describes a battery separator formed of a porous layer containing boehmite (plate-like particles) as fine particles.
  • the present invention has been made in view of the above problems, and an object thereof is to realize a non-aqueous electrolyte secondary battery having excellent discharge capacity recovery characteristics of a battery after a charge / discharge cycle.
  • the non-aqueous electrolyte secondary battery according to Aspect 1 of the present invention is based on a porous layer containing an inorganic filler and a resin and a MIT tester method defined in JIS P 8115 (1994).
  • the folding endurance test carried out at an angle of 45 °, the positive electrode plate having a bending frequency of 130 times or more before the electrode active material layer was peeled off, and in the folding endurance test, the bending frequency until the electrode active material layer was peeled off was 1650.
  • a negative electrode plate that is more than once, and the porous layer has a value represented by the following formula (1) in the range of 0.10 to 0.42.
  • the porous layer includes a polyolefin, a (meth) acrylate resin, a fluorine-containing resin, a polyamide resin, a polyester resin, and It includes a resin selected from the group consisting of water-soluble polymers.
  • the polyamide resin is an aramid resin.
  • the porous layer is laminated on one side or both sides of a polyolefin porous film.
  • the positive electrode plate contains a transition metal oxide and the negative electrode plate contains graphite.
  • a non-aqueous electrolyte secondary battery having excellent discharge capacity recovery characteristics of a battery after a charge / discharge cycle can be realized.
  • a non-aqueous electrolyte secondary battery is based on a porous layer containing an inorganic filler and a resin, a MIT tester method defined in JIS P 8115 (1994), a load of 1 N, In the folding endurance test carried out at a bending angle of 45 °, the positive electrode plate having a folding frequency of 130 times or more before the electrode active material layer was peeled off, and the folding frequency until the electrode active material layer was peeled off in the folding durability test. 1650 times or more, and the porous layer has a value represented by the following formula (1) in a range of 0.10 to 0.42.
  • the positive electrode plate in the non-aqueous electrolyte secondary battery according to the embodiment of the present invention is not particularly limited as long as the number of bending times measured in the folding endurance test is within a specific range as described below.
  • the positive electrode active material layer a sheet-shaped positive electrode plate in which a positive electrode mixture containing a positive electrode active material, a conductive agent and a binder is carried on a positive electrode current collector is used.
  • the positive electrode plate may carry the positive electrode mixture on both surfaces of the positive electrode current collector, or may carry the positive electrode mixture on one surface of the positive electrode current collector.
  • the positive electrode active material includes, for example, a material that can be doped with lithium ions and dedoped.
  • a transition metal oxide is preferable as the material.
  • Specific examples of the transition metal oxide include a lithium composite oxide containing at least one transition metal such as V, Mn, Fe, Co and Ni.
  • Examples of the conductive agent include carbonaceous materials such as graphite (natural graphite and artificial graphite), cokes, carbon black, pyrolytic carbons, carbon fibers, and organic polymer compound fired bodies.
  • the conductive agent may be used alone or in combination of two or more kinds.
  • binder examples include polyvinylidene fluoride, vinylidene fluoride copolymer, polytetrafluoroethylene, tetrafluoroethylene-hexafluoropropylene copolymer, tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer.
  • Thermoplastics such as ethylene-tetrafluoroethylene copolymer, vinylidene fluoride-hexafluoropropylene copolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene copolymer, thermoplastic polyimide, polyethylene and polypropylene Resins, acrylic resins, and styrene butadiene rubber are mentioned.
  • the binder also has a function as a thickener.
  • Examples of the positive electrode current collector include conductors such as Al, Ni, and stainless steel. Among them, Al is more preferable because it is easily processed into a thin film and is inexpensive.
  • the negative electrode plate in the non-aqueous electrolyte secondary battery according to the embodiment of the present invention is not particularly limited as long as the number of folding times measured in the folding endurance test is within a specific range as described below.
  • a sheet-shaped negative electrode in which a negative electrode mixture containing a negative electrode active material is carried on a negative electrode current collector is used as the negative electrode active material layer.
  • the sheet-shaped negative electrode plate preferably contains the conductive agent and the binder.
  • the negative electrode plate may carry the negative electrode mixture on both surfaces of the negative electrode current collector, or may carry the negative electrode mixture on one surface of the negative electrode current collector.
  • the negative electrode active material includes, for example, a material capable of being doped / dedoped with lithium ions, lithium metal or a lithium alloy.
  • the material include a carbonaceous material and the like.
  • the carbonaceous material include graphite (natural graphite, artificial graphite), cokes, carbon black, and pyrolytic carbons.
  • the conductive agent and the binder those described as the conductive agent and the binder which can be contained in the positive electrode active material layer can be used.
  • Examples of the negative electrode current collector include Cu, Ni, and stainless steel. Particularly, in a lithium ion secondary battery, Cu is more preferable because it is difficult to form an alloy with lithium and is easily processed into a thin film.
  • the positive electrode plate and the negative electrode plate according to one embodiment of the present invention are specified in the number of bendings until the active material layer is peeled off in a folding endurance test carried out in accordance with the MIT tester method defined in JIS P 8115 (1994). The range is.
  • the folding endurance test is performed at a load of 1 N and a bending angle of 45 °. In the non-aqueous electrolyte secondary battery, expansion and contraction of the active material may occur during the charge / discharge cycle.
  • the positive electrode plate is bent 130 times or more, preferably 150 times or more, until the electrode active material layer is peeled off.
  • the negative electrode plate has a number of folding times of 1650 or more, preferably 1800 or more, and more preferably 2000 or more, before the electrode active material layer is peeled off.
  • FIG. 1 is a schematic diagram showing an outline of the MIT test machine used in the MIT test machine method.
  • the x-axis represents the horizontal direction and the y-axis represents the vertical direction.
  • the outline of the MIT test machine method will be described below.
  • One end of the test piece in the longitudinal direction is clamped with a spring-loaded clamp, and the other end is clamped with a bending clamp.
  • the spring loaded clamp is connected to the weight.
  • the load by the weight is 1N.
  • the test piece is in a state of being tensioned in the longitudinal direction. In this state, the longitudinal direction of the test piece is parallel to the vertical direction.
  • the test piece is bent by rotating the bending clamp.
  • the bending angle at this time is 45 °. That is, the test piece is bent left and right at 45 °.
  • the speed of bending the test piece is 175 reciprocations / minute.
  • Examples of the method for producing a sheet-shaped positive electrode plate include a method in which a positive electrode active material, a conductive agent, and a binder are pressure-molded on a positive electrode current collector; a positive electrode active material, a conductive agent, and Examples include a method in which the binder is made into a paste, the paste is applied to the positive electrode current collector, and then the paste is adhered to the positive electrode current collector by applying pressure in a wet state or after drying.
  • a method for producing a sheet-shaped negative electrode plate for example, a method of press-molding the negative electrode active material on a negative electrode current collector; after making the negative electrode active material into a paste using an appropriate organic solvent, Examples thereof include a method of applying the paste to the negative electrode current collector and then applying pressure in a wet state or after drying to fix the negative electrode current collector.
  • the paste preferably contains the conductive agent and the binder.
  • the pressurizing time is preferably 1 to 3600 seconds, more preferably 1 to 300 seconds.
  • the pressurization may be performed by restraining the positive electrode plate or the negative electrode plate.
  • the pressure due to restraint is also referred to as restraint pressure.
  • the binding pressure is preferably 0.01 to 10 MPa, more preferably 0.01 to 5 MPa.
  • the positive electrode plate or the negative electrode plate may be pressurized while being wetted with an organic solvent. This can improve the adhesion between the components contained in the electrode active material layer and the adhesion between the electrode active material layer and the current collector.
  • the organic solvent include carbonates, ethers, esters, nitriles, amides, carbamates and sulfur-containing compounds, and fluorine-containing organic solvents obtained by introducing a fluorine group into these organic solvents. ..
  • the porous layer may be disposed between the polyolefin porous film and at least one of the positive electrode plate and the negative electrode plate as a member constituting the non-aqueous electrolyte secondary battery.
  • the porous layer may be formed on one side or both sides of the polyolefin porous film.
  • the porous layer may be formed on the active material layer of at least one of the positive electrode plate and the negative electrode plate.
  • the porous layer may be arranged between the polyolefin porous film and at least one of the positive electrode plate and the negative electrode plate so as to be in contact with them.
  • the porous layer disposed between the polyolefin porous film and at least one of the positive electrode plate and the negative electrode plate may be one layer or two or more layers.
  • the porous layer is preferably an insulating porous layer containing a resin.
  • the porous layer is laminated on one side of the polyolefin porous film
  • the porous layer is preferably laminated on the surface of the polyolefin porous film facing the positive electrode plate. More preferably, the porous layer is laminated on the surface in contact with the positive electrode plate.
  • the porous layer in one embodiment of the present invention contains an inorganic filler and a resin.
  • the porous layer has a large number of pores inside and has a structure in which these pores are connected, and is a layer through which gas or liquid can pass from one surface to the other surface.
  • the porous layer in one embodiment of the present invention is used as a member constituting a non-aqueous electrolyte secondary battery laminated separator described below, the porous layer is an electrode as an outermost layer of the laminated separator. Can be a layer in contact with.
  • the resin contained in the porous layer in one embodiment of the present invention is preferably insoluble in the electrolytic solution of the battery and is electrochemically stable in the usage range of the battery.
  • the resin include polyolefins; (meth) acrylate resins; fluorine-containing resins; polyamide resins; polyimide resins; polyester resins; rubbers; melting points or glass transition temperatures of 180 ° C. or higher.
  • Resins water-soluble polymers; polycarbonates, polyacetals, polyether ether ketones and the like.
  • polyolefin, (meth) acrylate resin, fluorine-containing resin, polyamide resin, polyester resin and water-soluble polymer are preferable.
  • polyethylene polyethylene, polypropylene, polybutene, ethylene-propylene copolymer and the like are preferable.
  • fluorine-containing resin examples include polyvinylidene fluoride (PVDF), polytetrafluoroethylene, vinylidene fluoride-hexafluoropropylene copolymer, tetrafluoroethylene-hexafluoropropylene copolymer, tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer Coalescence, vinylidene fluoride-tetrafluoroethylene copolymer, vinylidene fluoride-trifluoroethylene copolymer, vinylidene fluoride-trichloroethylene copolymer, vinylidene fluoride-vinyl fluoride copolymer, vinylidene fluoride-hexafluoro Examples thereof include propylene-tetrafluoroethylene copolymer, ethylene-tetrafluoroethylene copolymer and the like, and fluorine-containing rubber having a glass transition temperature of 23 ° C. or lower among the fluor
  • polyamide resin aramid resins such as aromatic polyamide and wholly aromatic polyamide are preferable.
  • the aramid resin examples include poly (paraphenylene terephthalamide), poly (metaphenylene isophthalamide), poly (parabenzamide), poly (metabenzamide), poly (4,4′-benzanilide terephthalate). Amide), poly (paraphenylene-4,4′-biphenylenedicarboxylic acid amide), poly (metaphenylene-4,4′-biphenylenedicarboxylic acid amide), poly (paraphenylene-2,6-naphthalenedicarboxylic acid amide), Poly (metaphenylene-2,6-naphthalenedicarboxylic acid amide), poly (2-chloroparaphenylene terephthalamide), paraphenylene terephthalamide / 2,6-dichloroparaphenylene terephthalamide copolymer, metaphenylene terephthalamide / 2 , 6-diclosure Paraphenylene terephthalamide copolymer and the like. Of these, poly (paraphenylene
  • polyester resin aromatic polyester such as polyarylate and liquid crystal polyester are preferable.
  • Examples of rubbers include styrene-butadiene copolymer and its hydride, methacrylic acid ester copolymer, acrylonitrile-acrylic acid ester copolymer, styrene-acrylic acid ester copolymer, ethylene propylene rubber, polyvinyl acetate and the like. Can be mentioned.
  • Examples of the resin having a melting point or glass transition temperature of 180 ° C. or higher include polyphenylene ether, polysulfone, polyether sulfone, polyphenylene sulfide, polyetherimide, polyamideimide, and polyetheramide.
  • water-soluble polymers examples include polyvinyl alcohol, polyethylene glycol, cellulose ether, sodium alginate, polyacrylic acid, polyacrylamide, polymethacrylic acid and the like.
  • the resin contained in the porous layer in the embodiment of the present invention may be one kind or a mixture of two or more kinds.
  • a fluorine-containing resin is preferable because it can be easily maintained.
  • the porous layer in one embodiment of the present invention contains an inorganic filler.
  • the lower limit of the content is preferably 50% by weight or more and 70% by weight or more based on the total weight of the filler and the resin constituting the porous layer in the embodiment of the present invention. More preferably, it is more preferably 90% by weight or more.
  • the upper limit of the content of the inorganic filler in the porous layer in the embodiment of the present invention is preferably 99% by weight or less, and more preferably 98% by weight or less.
  • the content of the filler is preferably 50% by weight or more from the viewpoint of heat resistance, and the content of the filler is preferably 99% by weight or less from the viewpoint of adhesion between the fillers.
  • the inorganic filler is not particularly limited as long as it is a filler that is stable in a non-aqueous electrolytic solution and is electrochemically stable. From the viewpoint of ensuring the safety of the battery, a filler having a heat resistant temperature of 150 ° C. or higher is preferable.
  • the inorganic filler is not particularly limited, but is usually an insulating filler.
  • the inorganic filler is preferably an inorganic material containing at least one element selected from the group consisting of aluminum element, zinc element, calcium element, zirconium element, silicon element, magnesium element, barium element, and boron element, and preferably Is an inorganic substance containing an aluminum element. Further, the inorganic filler preferably contains an oxide of the metal element.
  • the inorganic filler titanium oxide, alumina (Al 2 O 3 ), zinc oxide (ZnO), calcium oxide (CaO), zirconia oxide (ZrO 2 ), silica, magnesia, barium oxide, boron oxide, Examples thereof include mica, wollastonite, attapulgite, and boehmite (alumina monohydrate).
  • the inorganic filler one kind of filler may be used alone, or two or more kinds of filler may be used in combination.
  • the inorganic filler in the porous layer in one embodiment of the present invention preferably contains alumina and a plate-like filler.
  • the plate-like filler include one or more fillers selected from the group consisting of zinc oxide (ZnO), mica, and boehmite among the oxides of the metal elements listed above.
  • the volume average particle size of the inorganic filler is preferably in the range of 0.01 ⁇ m to 10 ⁇ m from the viewpoint of ensuring good adhesiveness and slipperiness, and moldability of the laminate.
  • the lower limit value is more preferably 0.05 ⁇ m or more, further preferably 0.1 ⁇ m or more.
  • the upper limit value is more preferably 5 ⁇ m or less, further preferably 1 ⁇ m or less.
  • the shape of the inorganic filler is arbitrary and is not particularly limited.
  • the shape of the inorganic filler may be a particle shape, for example, a spherical shape; an elliptical shape; a plate shape; a rod shape; an indefinite shape; a fibrous shape; a spherical or columnar single particle such as a peanut shape and / or a tetrapot shape.
  • the shape may be any of the above.
  • the inorganic filler is preferably plate-like particles and / or non-aggregated primary particles.
  • the shape of the inorganic filler is such that the particles in the porous material are difficult to be most closely packed, voids are easily formed between the particles, bumps, dents, constrictions, ridges or bulges, and dendritic
  • a single particle is heat-fused such as an indeterminate shape such as a shape, a coral shape, or a tuft shape; a fibrous shape; a peanut shape and / or a tetrapot shape.
  • the shape of the inorganic filler is particularly preferably a shape in which spherical or columnar single particles such as peanut-shaped and / or tetrapot-shaped particles are heat-sealed.
  • the filler can improve slipperiness by forming fine irregularities on the surface of the porous layer.
  • the filler is a plate-like particle and / or a primary particle that is not aggregated, the unevenness formed on the surface of the porous layer by the filler becomes finer, and the adhesiveness between the porous layer and the electrode is further improved. It will be good.
  • the oxygen atom mass percentage of the metal oxide constituting the inorganic filler contained in the porous layer in one embodiment of the present invention is preferably 10% to 50%, more preferably 20% to 50%. preferable.
  • the affinity between the solvent or the dispersion medium in the coating liquid used in the method for producing a porous layer described later and the inorganic filler is preferably adjusted. It is possible to maintain the distance between the above-mentioned inorganic fillers at an appropriate distance. As a result, the dispersibility of the coating liquid can be improved, and as a result, the above formula (1) can be controlled within an appropriate specified range.
  • the porous layer in one embodiment of the present invention may contain other components than the above-mentioned inorganic filler and resin.
  • the other components include surfactants, waxes and binder resins.
  • the content of the other components is preferably 0% by weight to 50% by weight based on the weight of the entire porous layer.
  • the average film thickness of the porous layer in one embodiment of the present invention is preferably in the range of 0.5 ⁇ m to 10 ⁇ m per one layer of the porous layer from the viewpoint of ensuring adhesiveness to the electrode and high energy density. More preferably, it is in the range of 1 ⁇ m to 5 ⁇ m.
  • the basis weight per unit area of the porous layer can be appropriately determined in consideration of the strength, film thickness, weight and handling property of the porous layer.
  • the basis weight per unit area of the porous layer is preferably 0.5 to 20 g / m 2 and more preferably 0.5 to 10 g / m 2 per porous layer.
  • the weight energy density and volume energy density of the non-aqueous electrolyte secondary battery can be increased.
  • the basis weight of the porous layer exceeds the above range, the non-aqueous electrolyte secondary battery tends to be heavy.
  • the porosity of the porous layer is preferably 20 to 90% by volume, and more preferably 30 to 80% by volume so that sufficient ion permeability can be obtained.
  • the pore size of the pores of the porous layer is preferably 1.0 ⁇ m or less, more preferably 0.5 ⁇ m or less. By setting the pore diameters to these sizes, the non-aqueous electrolyte secondary battery can obtain sufficient ion permeability.
  • the value represented by the following formula (1) is preferably in the range of 0.10 to 0.42, and in the range of 0.10 to 0.30. More preferably.
  • T represents a distance to a critical load in a scratch test under a constant load of 0.1 N in TD
  • M represents a scratch test under a constant load of 0.1 N in MD.
  • the ratio of the distance (T) to the critical load in TD and the distance (M) to the critical load in MD measured by the above scratch test is an index showing the orientation of the inorganic filler in the porous layer. ..
  • FIG. 2 shows a schematic diagram of the state of the inorganic filler in the porous layer when the orientation is high (anisotropic) and when the orientation is low (isotropic). The left view of FIG.
  • FIG. 2 is a schematic view showing the structure of the porous layer containing an inorganic filler, in which the orientation of the inorganic filler is large and exhibits anisotropy, and the right view of FIG. It is a schematic diagram showing the structure of the said porous layer in case the orientation of an inorganic filler is small and it shows isotropic property.
  • the value represented by the above formula (1) is a value indicating the anisotropy of the distance to the critical load in the scratch test. The closer the value is to zero, the more isotropic the distance to the critical load is. Indicates that there is.
  • the value represented by the formula (1) is also simply referred to as “formula (1)”.
  • the "scratch test" in the present invention means, as shown in FIG. 3, a constant load is applied to the indenter, and the porous membrane is moved horizontally while the surface layer of the porous membrane to be measured is compressed and deformed in the thickness direction.
  • This is a test for measuring the stress generated at a certain indenter movement distance when the pressure is applied.
  • the state in which the surface layer of the porous membrane is compressed and deformed in the thickness direction is the state in which the indenter is pushed into the porous membrane.
  • the test is specifically carried out by the following method: (1) A laminate, which is a laminated porous film obtained by laminating a measurement target porous layer on a porous substrate, is cut into 20 mm ⁇ 60 mm.
  • the cut laminated body 3 is pasted on a 30 mm ⁇ 70 mm glass preparation, which is the substrate 2, with an aqueous paste, and dried at 25 ° C. for 24 hours to prepare a test sample. ..
  • bubbles are prevented from entering between the laminated body and the glass slide.
  • the test sample prepared in the step (1) is installed in a micro scratch test device. With the diamond indenter 1 in the test apparatus, while the vertical load of 0.1 N is applied to the test sample, the table in the test apparatus is directed toward the TD of the laminated body at 5 mm / min. At speed, move a distance of 10 mm.
  • a frictional force which is a stress generated between the diamond indenter and the test sample.
  • a curve graph showing the relationship between the displacement of the stress measured in the step (2) and the moving distance of the table is created, and from the curve graph, as shown in FIG. Calculate the value and the distance to reach the critical load.
  • the moving direction of the table is changed to MD, and the above steps (1) to (3) are repeated to calculate the critical load value and the distance to reach the critical load in MD.
  • the distance to the critical load value calculated by the scratch test is (a) an index of plastic deformation easiness of the surface of the laminated porous film, (b) an index of transmissibility of shear stress to the surface opposite to the measurement surface. Becomes The long distance to the critical load value means that in the laminated porous film to be measured, (a ') the surface layer portion is less likely to be plastically deformed, and (b') the transmission of shear stress to the surface opposite to the measurement surface. Is low, that is, it is difficult for stress to be transmitted.
  • the ion permeation resistance of the porous layer increases, and the resistance of the separator in the non-aqueous electrolyte secondary battery increases.
  • the above formula (1) is less than 0.10, it is considered that the structure of the porous layer is a structure having an excessively high isotropic property.
  • the structure of the porous layer has an excessively high isotropic property, in a non-aqueous electrolyte secondary battery incorporating the porous layer, the electrolyte receiving ability of the porous layer during battery operation tends to be excessively high. There is.
  • the electrolyte solution supply capabilities of the separator base material and the electrode that are in contact with the porous layer and supply the electrolyte solution to the porous layer will control the flow rate of the electrolyte solution of the entire non-aqueous electrolyte secondary battery.
  • the resistance of the separator in the non-aqueous electrolyte secondary battery increases.
  • the median particle diameter (D50) of the inorganic filler is preferably in the range of 0.1 ⁇ m to 11 ⁇ m, more preferably in the range of 0.1 ⁇ m to 10 ⁇ m, and 0 The range is more preferably from 1 ⁇ m to 5 ⁇ m, and particularly preferably 0.5 ⁇ m.
  • the method for measuring the median particle diameter of the inorganic filler is not particularly limited, but for example, it is measured by the method described in the examples.
  • the center particle size of the inorganic filler is larger than 11 ⁇ m, the film thickness of the heat-resistant layer increases and unevenness occurs, resulting in unevenness in ion permeation of the porous layer. As a result, the resistance of the separator in the non-aqueous electrolyte secondary battery incorporating the porous layer tends to increase.
  • the median particle diameter of the inorganic filler is less than 0.1 ⁇ m, the viscosity of the coating liquid containing the inorganic filler becomes high, which may cause dilatancy. As a result, the coating liquid may have poor coating performance and uneven coating on the porous layer may occur.
  • the central particle diameter of the inorganic filler is small, the amount of binder required to bind the inorganic filler increases.
  • the ion permeation resistance of the porous layer increases, and the resistance of the separator in the non-aqueous electrolyte secondary battery increases.
  • the BET specific surface area per unit area of the inorganic filler is preferably 100 m 2 / g or less, more preferably 50 m 2 / g or less, and 10 m 2 / g. It may be the following.
  • the method for measuring the BET specific surface area per unit area of the inorganic filler is not particularly limited, and examples thereof include a method including the steps (1) to (3) below.
  • the pretreatment device and the measurement device are not particularly limited.
  • BELPREP-vacII manufactured by Microtrac Bell Co., Ltd.
  • BELSORP-mini manufactured by Microtrac Bell Co., Ltd.
  • the measurement conditions for measuring the specific surface area of the filler are not particularly limited and can be appropriately set by those skilled in the art.
  • the BET specific surface area per unit area of the inorganic filler is larger than 100 m 2 / g, the filler oiling property is increased due to the increase in the BET specific surface area, and accordingly, the properties of the porous layer as a coating liquid are decreased, There is a risk of poor coatability. As a result, the resistance of the separator in the non-aqueous electrolyte secondary battery incorporating the porous layer tends to increase.
  • the method for producing the porous layer according to the embodiment of the present invention is not particularly limited, but for example, one of the following steps (1) to (3) may be used on the substrate, A method of forming a porous layer containing the inorganic filler and the resin can be mentioned.
  • the porous layer can be produced by depositing the resin and then drying it to remove the solvent.
  • the coating liquid in steps (1) to (3) may be in a state in which the inorganic filler is dispersed and the resin is dissolved.
  • the solvent can be said to be a solvent for dissolving the resin and a dispersion medium for dispersing the resin or the inorganic filler.
  • the base material After applying a coating liquid containing the inorganic filler and the resin on the surface of the base material, the base material is immersed in a deposition solvent that is a poor solvent for the resin, A step of depositing a resin to form a porous layer.
  • the liquid property of the coating liquid is made acidic by using a low-boiling organic acid, A step of depositing a resin to form a porous layer.
  • the solvent does not adversely affect the base material, dissolves the resin uniformly and stably, and disperses the inorganic filler uniformly and stably.
  • the solvent include N-methyl-2-pyrrolidone, N, N-dimethylacetamide, N, N-dimethylformamide, acetone and water.
  • the deposition solvent for example, isopropyl alcohol or t-butyl alcohol is preferably used.
  • the low boiling point organic acid for example, paratoluenesulfonic acid, acetic acid, etc. can be used.
  • the coating amount (that is, basis weight) of the porous layer is usually 0.5 to 20 g / solid per one layer of the porous layer from the viewpoint of adhesiveness to an electrode or an electrode sheet and ion permeability. is preferably m 2, more preferably from 0.5 ⁇ 10g / m 2, more preferably in the range of 0.5g / m 2 ⁇ 1.5g / m 2. That is, it is preferable to adjust the amount of the coating liquid applied on the substrate so that the coating amount (area weight) of the obtained porous layer falls within the above range.
  • a coating containing an inorganic filler and a resin used for producing the porous layer examples thereof include adjusting the solid content concentration of the working liquid, and adjusting the coating shear rate when the coating liquid is applied onto the substrate.
  • a suitable solid content concentration of the coating liquid may vary depending on the type of filler, etc., but generally it is preferably more than 20% by weight and 40% by weight or less. It is preferable for the solid content concentration to be in the above range from the viewpoint that the viscosity of the coating liquid can be appropriately maintained and, as a result, the above formula (1) can be controlled within an appropriate prescribed range.
  • the coating shear rate at the time of applying the coating liquid on the substrate may vary depending on the type of filler, etc., but generally it is preferably 2 (1 / s) or more and 4 (1 / s). More preferably, it is from s) to 50 (1 / s).
  • the inorganic filler a shape in which spherical or columnar single particles such as peanut-shaped and / or tetrapot-shaped are heat-fused, spherical-shaped, elliptical-shaped, plate-shaped, rod-shaped, or irregular-shaped.
  • the coating shear rate is increased, a high shearing force is applied to the inorganic filler, so that the anisotropy tends to increase.
  • the coating shear rate is reduced, the shearing force is not applied to the inorganic filler, so that the inorganic filler tends to be oriented isotropically.
  • the inorganic filler is a long fiber diameter inorganic filler such as long wollastonite having a large fiber diameter
  • the coating shear rate is increased, the long fibers are entangled with each other, or the long blades of the doctor blade are long fibers. Tend to be in a disoriented orientation due to the trapping of the, and anisotropy tends to be low.
  • the coating shear rate is reduced, the long fibers do not become entangled with each other and do not get caught by the blade of the doctor blade, so that they tend to be oriented and the anisotropy tends to increase.
  • a separator for a non-aqueous electrolyte secondary battery according to an embodiment of the present invention includes a polyolefin porous film.
  • the separator for a non-aqueous electrolyte secondary battery may further include other layers such as an adhesive layer, a heat resistant layer, and a protective layer, in addition to the polyolefin porous film.
  • the non-aqueous electrolyte secondary battery in one embodiment of the present invention may include a polyolefin porous film.
  • a polyolefin porous film may only be called a "porous film.”
  • the porous film contains a polyolefin-based resin as a main component and has a large number of pores connected to the inside thereof, so that a gas and a liquid can pass from one surface to the other surface.
  • the porous film alone can serve as a separator for a non-aqueous electrolyte secondary battery. It can also serve as a porous base material in the laminated separator for a non-aqueous electrolyte secondary battery in which the above-mentioned porous layer is laminated.
  • a laminate in which the porous layer is laminated in the present specification, also referred to as "non-aqueous electrolyte secondary battery laminated separator” or “laminated separator” ..
  • the proportion of polyolefin in the porous film is 50% by volume or more of the entire porous film, more preferably 90% by volume or more, and further preferably 95% by volume or more. Further, it is more preferable that the polyolefin contains a high molecular weight component having a weight average molecular weight of 5 ⁇ 10 5 to 15 ⁇ 10 6 . In particular, when the polyolefin contains a high molecular weight component having a weight average molecular weight of 1,000,000 or more, the strength of the separator for a non-aqueous electrolyte secondary battery is improved, which is more preferable.
  • the polyolefin which is a thermoplastic resin
  • a copolymer may be used.
  • the homopolymer include polyethylene, polypropylene and polybutene.
  • the copolymer include ethylene-propylene copolymer.
  • polyethylene is more preferable because it can block excessive current from flowing at lower temperatures. Note that blocking the flow of this excessive current is also referred to as shutdown.
  • the polyethylene include low density polyethylene, high density polyethylene, linear polyethylene (ethylene- ⁇ -olefin copolymer), and ultrahigh molecular weight polyethylene having a weight average molecular weight of 1,000,000 or more. Among these, ultrahigh molecular weight polyethylene having a weight average molecular weight of 1,000,000 or more is more preferable.
  • the thickness of the porous film is preferably 4 to 40 ⁇ m, more preferably 5 to 30 ⁇ m, and further preferably 6 to 15 ⁇ m.
  • the basis weight per unit area of the porous film can be appropriately determined in consideration of strength, film thickness, weight and handleability.
  • the basis weight is preferably 4 to 20 g / m 2 , and preferably 4 to 12 g / m 2 so that the weight energy density and the volume energy density of the non-aqueous electrolyte secondary battery can be increased. More preferably, it is more preferably 5 to 10 g / m 2 .
  • the air permeability of the porous film is preferably 30 to 500 sec / 100 mL in Gurley value, and more preferably 50 to 300 sec / 100 mL.
  • the air permeability of the laminated separator for a non-aqueous electrolyte secondary battery in which the above-mentioned porous layer is laminated on the porous film is preferably 30 to 1000 sec / 100 mL in terms of Gurley value, and is 50 to 800 sec / 100 mL. Is more preferable. Since the laminated separator for a non-aqueous electrolyte secondary battery has the above-mentioned air permeability, it is possible to obtain sufficient ion permeability in the non-aqueous electrolyte secondary battery.
  • the porosity of the porous film is preferably 20 to 80% by volume so as to increase the holding amount of the electrolytic solution and to surely prevent the flow of an excessive current at a lower temperature. It is more preferably 30 to 75% by volume.
  • the pore size of the pores of the porous film is 0.3 ⁇ m or less so that sufficient ion permeability can be obtained and particles can be prevented from entering the positive electrode plate and the negative electrode plate. Is preferably 0.14 ⁇ m or less, and more preferably 0.14 ⁇ m or less.
  • the method for producing the polyolefin porous film is not particularly limited.
  • a sheet-shaped polyolefin resin composition is prepared by kneading a polyolefin resin, a pore-forming agent such as an inorganic filler and a plasticizer, and optionally an antioxidant and the like and then extruding the kneaded product. After removing the pore-forming agent from the sheet-shaped polyolefin resin composition with an appropriate solvent, the polyolefin resin composition from which the pore-forming agent has been removed may be stretched to produce a polyolefin porous film. it can.
  • the above-mentioned inorganic filler is not particularly limited, and examples thereof include inorganic fillers, specifically calcium carbonate and the like.
  • the plasticizer is not particularly limited, and examples thereof include low molecular weight hydrocarbons such as liquid paraffin.
  • a method including the following steps can be mentioned.
  • A a step of kneading an ultrahigh molecular weight polyethylene, a low molecular weight polyethylene having a weight average molecular weight of 10,000 or less, a pore forming agent such as calcium carbonate or a plasticizer, and an antioxidant to obtain a polyolefin resin composition
  • B a step of rolling the obtained polyolefin resin composition with a pair of rolling rollers and gradually cooling it while pulling it with a take-up roller having a different speed ratio to form a sheet
  • C a step of removing the pore forming agent from the obtained sheet with a suitable solvent
  • D A step of stretching the sheet from which the pore forming agent has been removed at an appropriate stretching ratio.
  • Examples of the method for producing a laminated separator for a non-aqueous electrolyte secondary battery in one embodiment of the present invention include, for example, in the above-mentioned “method for producing a porous layer”, as the base material to which the coating liquid is applied, The method of using a polyolefin porous film can be mentioned.
  • the non-aqueous electrolyte that can be included in the non-aqueous electrolyte secondary battery according to the embodiment of the present invention is not particularly limited as long as it is a non-aqueous electrolyte that is generally used in non-aqueous electrolyte secondary batteries.
  • a non-aqueous electrolyte obtained by dissolving a lithium salt in an organic solvent can be used.
  • lithium salt examples include LiClO 4 , LiPF 6 , LiAsF 6 , LiSbF 6 , LiBF 4 , LiCF 3 SO 3 , LiN (CF 3 SO 2 ) 2 , LiC (CF 3 SO 2 ) 3 , Li 2 B 10 Cl. 10 , lower aliphatic carboxylic acid lithium salt, LiAlCl 4 and the like.
  • the lithium salt may be used alone or in combination of two or more kinds.
  • organic solvent that constitutes the non-aqueous electrolytic solution
  • examples of the organic solvent that constitutes the non-aqueous electrolytic solution include carbonates, ethers, esters, nitriles, amides, carbamates and sulfur-containing compounds, and fluorine-containing compounds introduced into these organic solvents. Fluorine organic solvents and the like can be mentioned.
  • the organic solvent may be used alone or in combination of two or more.
  • Examples of the method for producing the non-aqueous electrolyte secondary battery according to the embodiment of the present invention include the following methods. First, the positive electrode plate, the porous layer, the non-aqueous electrolyte secondary battery separator, and the negative electrode plate are arranged in this order to form a non-aqueous electrolyte secondary battery member. After that, the member for a non-aqueous electrolyte secondary battery is put in a container that will be the casing of the non-aqueous electrolyte secondary battery, and then the inside of the container is filled with the non-aqueous electrolyte solution and then sealed while depressurizing. Thereby, the non-aqueous electrolyte secondary battery according to the embodiment of the present invention can be manufactured.
  • the non-aqueous electrolyte secondary battery according to one embodiment of the present invention is, as described above, a separator for a non-aqueous electrolyte secondary battery including a polyolefin porous film, a porous layer, a positive electrode plate, and a negative electrode plate. And are equipped with.
  • the non-aqueous electrolyte secondary battery according to the embodiment of the present invention satisfies the following requirements (i) to (iii).
  • the porous layer has a value represented by the following formula (1) in the range of 0.10 to 0.42.
  • T represents a distance to a critical load in a scratch test under a constant load of 0.1 N in TD
  • M represents a scratch test under a constant load of 0.1 N in MD.
  • the porous layer Due to the requirement of (i), in the non-aqueous electrolyte secondary battery according to the embodiment of the present invention, the porous layer has a uniform and dense structure, so that the distribution of lithium ions in the porous layer is uniform. Retained. Then, due to the requirements (ii) and (iii), the entire electrode easily isotropically follows the expansion and contraction of the active material. Therefore, the adhesiveness between the components contained in the electrode active material layer and the adhesiveness between the electrode active material layer and the current collector are easily maintained.
  • a MIT type folding endurance tester manufactured by Yasuda Seiki
  • load 1N
  • bent portion R 0.38mm
  • bending speed 175 reciprocations / minute one end of the test piece was fixed, and the test piece was bent left and right at an angle of 45 degrees.
  • the number of times of bending until the electrode active material layer was peeled from the positive electrode plate or the negative electrode plate was measured.
  • the number of times of bending here is the number of times of reciprocal bending displayed on the counter of the MIT folding endurance tester.
  • an arabic Yamato aqueous liquid paste (manufactured by Yamato Co., Ltd.) diluted 5 times with water was applied on the separator side of the cut laminate, that is, the entire surface of the porous substrate side, in a small amount of about 1.5 g / m 2 per unit area. It was applied thinly.
  • the surface coated with the aqueous liquid paste was pasted on a glass slide having a size of 30 mm ⁇ 70 mm and then dried at 25 ° C. for 24 hours to prepare a test sample. At the time of the above-mentioned bonding, bubbles were prevented from entering between the laminate and the glass slide.
  • step (2) The test sample prepared in step (1) was placed in a micro scratch tester (manufactured by CSEM Instruments). With the diamond indenter (conical shape having an apex angle of 120 ° and a tip radius of 0.2 mm) in the test apparatus, a vertical load of 0.1 N was applied to the test sample in the test apparatus. The table was moved toward the TD of the laminate at a speed of 5 mm / min and a distance of 10 mm. During that time, the stress generated between the diamond indenter and the test sample, that is, the frictional force was measured. (3) A curve graph showing the relationship between the displacement of the stress measured in the step (2) and the moving distance of the table was created. From the curve graph, the critical load value in TD and the distance to reach the critical load were calculated. (4) The moving direction of the table was changed to MD, and the above steps (1) to (3) were repeated to calculate the critical load value and the distance to reach the critical load in MD.
  • the thicknesses of the porous layer, the porous substrate, the positive electrode active material layer and the negative electrode active material layer were measured using a high precision digital length measuring machine (VL-50) manufactured by Mitutoyo Corporation.
  • the thickness of the positive electrode active material layer is calculated by subtracting the thickness of the aluminum foil that is the current collector from the thickness of the positive electrode plate, and the thickness of the negative electrode active material layer is the thickness of the negative electrode plate. It was calculated by subtracting the thickness of the copper foil, which is the current collector, from. Further, the thickness of the porous layer was calculated by subtracting the thickness of the uncoated portion from the thickness of the coated portion of each laminate.
  • the coated portion refers to the portion where the porous layer is formed, and the uncoated portion refers to the portion where the porous layer is not formed.
  • the volume-based particle size distribution of the filler was calculated by measuring D10, D50, and D90 using a laser diffraction particle size distribution analyzer SALD2200 manufactured by Shimadzu Corporation.
  • SALD2200 laser diffraction particle size distribution analyzer
  • the particle diameter at which the cumulative distribution based on volume is 50%, the particle diameter at 10%, and the particle diameter at 90% are called D50, D10, and D90, respectively.
  • D50 is also referred to as the median particle size.
  • the specific surface area of the filler was measured using BELSORP-mini (manufactured by Microtrac Bell Co., Ltd.).
  • the adsorption-desorption isotherm by nitrogen of the filler that had been vacuum dried at a pretreatment temperature of 80 ° C. for 8 hours was measured by the constant volume method, and calculated by the BET method.
  • Various conditions in the constant volume method are as follows: adsorption temperature; 77 K, adsorbate; nitrogen, saturated vapor pressure; measured value, adsorbate cross section; 0.162 nm 2 , equilibrium waiting time (adsorption equilibrium state (adsorption Waiting time after the pressure change during desorption reaches a value below a predetermined value)): 500 sec.
  • the pore volume was calculated by the MP method and the BJH method, and the pretreatment device used was BELPREP-vacII (manufactured by Microtrac Bell Co., Ltd.).
  • CC-CV charging is a charging method in which charging is performed with a set constant current, and after reaching a predetermined voltage, the current is reduced while maintaining the voltage.
  • CC discharge is a method of discharging to a predetermined voltage with a set constant current. The meanings of these terms are the same in this specification.
  • the discharge capacity at the third cycle was defined as the discharge recovery capacity. In Table 1 described later, the discharge recovery capacity is shown as “discharge recovery capacity after 100 cycles”.
  • the above-mentioned discharge recovery capacity test is a test method in which discharge is carried out at a low rate (0.2 C) after 100 charge / discharge cycles and the discharge capacity is confirmed more accurately. In particular, the degree of deterioration of the discharge performance of the electrode can be confirmed.
  • This sheet was immersed in an aqueous hydrochloric acid solution prepared by mixing 0.5 mol% of a nonionic surfactant in 4 mol / L hydrochloric acid to dissolve and remove calcium carbonate. Then, the said sheet
  • (B layer)) (Production of coating liquid)
  • the inorganic filler hexagonal plate-shaped zinc oxide having a mass percentage of oxygen atoms of 20% (manufactured by Sakai Chemical Industry Co., Ltd., trade name: XZ-100F) was used.
  • D50, D10, and D90 of the inorganic filler 1 were 0.4 ⁇ m, 0.2 ⁇ m, and 2.1 ⁇ m, respectively.
  • the BET specific surface area per unit area of the inorganic filler 1 was 7.3 m 2 / g.
  • a binder resin As a binder resin, a vinylidene fluoride-hexafluoropropylene copolymer (manufactured by Arkema Ltd .: trade name “KYNAR2801”) was used.
  • the inorganic filler, vinylidene fluoride-hexafluoropropylene copolymer and solvent were mixed in the following proportions. That is, 10 parts by weight of vinylidene fluoride-hexafluoropropylene copolymer is mixed with 90 parts by weight of inorganic filler, and the solid content in the resulting mixed liquid (inorganic filler and vinylidene fluoride-hexafluoropropylene copolymer).
  • the solvent was mixed so that the concentration of was 37% by weight.
  • the obtained mixed liquid was stirred and mixed with a thin film swivel type high speed mixer (Filmiku (registered trademark) manufactured by Primix Co., Ltd.) to obtain a uniform coating liquid 1.
  • the obtained coating liquid 1 was applied to one surface of the A layer by a doctor blade method at a coating shear rate of 3.9 (1 / s) to form a coating film on one surface of the A layer. ..
  • the coating film was dried at 65 ° C. for 20 minutes to form a B layer on one surface of the A layer.
  • a laminated body 1 laminated on which the B layer was laminated on one surface of the A layer was obtained.
  • the weight of the B layer was 7 g / m 2 and the thickness was 4 ⁇ m.
  • a positive electrode plate 1 was obtained.
  • the thickness of the positive electrode active material layer was 38 ⁇ m.
  • Negative electrode plate A negative electrode mixture of natural graphite / styrene-1,3-butadiene copolymer / sodium carboxymethyl cellulose (weight ratio 98/1/1) having a volume-based average particle diameter (D50) of 15 ⁇ m was used as a negative electrode current collector ( A negative electrode plate laminated on one surface of the copper foil) was obtained. A binding pressure (0.7 MPa) was applied to this negative electrode plate at room temperature for 30 seconds.
  • a negative electrode plate 1 was obtained.
  • the thickness of the negative electrode active material layer was 38 ⁇ m.
  • a non-aqueous electrolyte secondary battery was manufactured using the positive electrode plate 1, the negative electrode plate 1 and the laminate 1 by the method described below.
  • the positive electrode plate 1 and the negative electrode plate 1 were arranged such that the entire main surface of the positive electrode active material layer of the positive electrode plate 1 was included in the range of the main surface of the negative electrode active material layer of the negative electrode plate 1. That is, the positive electrode plate 1 and the negative electrode plate 1 were arranged so that the entire main surface of the positive electrode active material layer of the positive electrode plate 1 overlaps the main surface of the negative electrode active material layer of the negative electrode plate 1. Further, the surface of the laminated body 1 on the side of the porous layer was opposed to the positive electrode active material layer of the positive electrode plate 1.
  • the non-aqueous electrolyte secondary battery member 1 was placed in a previously prepared bag in which an aluminum layer and a heat seal layer were laminated, and 0.23 mL of the non-aqueous electrolyte solution was further placed in this bag. It was The non-aqueous electrolyte solution should be dissolved in a mixed solvent prepared by mixing ethylene carbonate, ethylmethyl carbonate and diethyl carbonate in a volume ratio of 3: 5: 2 so that the concentration of LiPF 6 is 1 mol / L. Was prepared by. Then, the inside of the bag was depressurized and the bag was heat-sealed to manufacture the non-aqueous electrolyte secondary battery 1.
  • Example 2 [Preparation of porous layer and laminate]
  • the inorganic filler 2 a mixture of spherical alumina (Sumitomo Chemical Co., Ltd., trade name AA03) and mica (Wako Pure Chemical Industries, Ltd., trade name: non-swelling synthetic mica) was used. The above mixture was prepared by mixing 50 parts by weight of spherical alumina and 50 parts by weight of mica in a mortar. The oxygen atom mass percentage of the inorganic filler 2 was 45%. Further, D50, D10 and D90 of the inorganic filler 2 were 4.2 ⁇ m, 0.5 ⁇ m and 11.5 ⁇ m, respectively. Furthermore, the BET specific surface area per unit area of the inorganic filler 2 was 4.5 m 2 / g.
  • the coating liquid was prepared as follows. That is, 10 parts by weight of vinylidene fluoride-hexafluoropropylene copolymer was mixed with 90 parts by weight of inorganic filler, and the solid content in the resulting mixed liquid (inorganic filler + vinylidene fluoride-hexafluoropropylene copolymer). The solvent was mixed so that the concentration of was 30% by weight. The obtained mixed liquid was stirred and mixed by a thin film swivel type high speed mixer to obtain a uniform coating liquid 2.
  • the inorganic filler 1 used for producing the porous layer (B layer) was changed to the above inorganic filler 2, the coating liquid 1 was changed to the above coating liquid 2, and the coating shear rate was 7.9 (1 / s).
  • a layered product 2 was obtained in the same manner as in Example 1 except that the content was changed to).
  • a non-aqueous electrolyte secondary battery 2 was obtained in the same manner as in Example 1 except that the laminate 2 was used instead of the laminate 1.
  • Example 3 [Preparation of porous layer and laminate]
  • wollastonite (Hayashi Kasei Co., Ltd., trade name: Wollastonite VM-8N) having an oxygen atomic mass percentage of 42% was used.
  • D50, D10, and D90 of the inorganic filler 3 were 10.6 ⁇ m, 2.4 ⁇ m, and 25.3 ⁇ m, respectively.
  • the BET specific surface area per unit area of the inorganic filler 3 was 1.3 m 2 / g.
  • the coating liquid was prepared as follows. That is, 10 parts by weight of vinylidene fluoride-hexafluoropropylene copolymer was mixed with 90 parts by weight of inorganic filler, and the solid content in the resulting mixed liquid (inorganic filler + vinylidene fluoride-hexafluoropropylene copolymer). The solvent was mixed so that the concentration of was 40% by weight. The obtained mixed liquid was stirred and mixed with a thin film swivel type high speed mixer to obtain a uniform coating liquid 3.
  • the inorganic filler 1 used in the preparation of the porous layer (B layer) was changed to the above inorganic filler 3, the coating liquid 1 was changed to the above coating liquid 3, and the coating shear rate was 7.9 (1 / s A laminated body 3 was obtained in the same manner as in Example 1 except that the layer structure 3 was changed to).
  • a non-aqueous electrolyte secondary battery 3 was obtained in the same manner as in Example 1 except that the laminate 3 was used instead of the laminate 1.
  • Example 4 [Preparation of porous layer and laminate]
  • the inorganic filler 4 a mixture of ⁇ -alumina (Sumitomo Chemical Co., Ltd., trade name: AKP3000) and hexagonal plate-shaped zinc oxide (Sakai Chemical Industry Co., Ltd., trade name: XZ-1000F) was used.
  • the above mixture was prepared by mixing 99 parts by weight of ⁇ -alumina and 1 part by weight of hexagonal plate-shaped zinc oxide in a mortar.
  • the oxygen atom mass percentage of the inorganic filler 4 was 47%.
  • D50, D10, and D90 of the inorganic filler 4 were 0.8 ⁇ m, 0.4 ⁇ m, and 2.2 ⁇ m, respectively.
  • the BET specific surface area per unit area of the inorganic filler 4 was 4.5 m 2 / g.
  • the coating liquid was prepared as follows. That is, 10 parts by weight of vinylidene fluoride-hexafluoropropylene copolymer was mixed with 90 parts by weight of inorganic filler, and the solid content in the resulting mixed liquid (inorganic filler + vinylidene fluoride-hexafluoropropylene copolymer). The solvent was mixed so that the concentration of was 40% by weight. The obtained mixed liquid was stirred and mixed by a thin film swivel type high speed mixer to obtain a uniform coating liquid 4.
  • the inorganic filler 1 used for producing the porous layer (B layer) was changed to the above inorganic filler 4, the coating liquid 1 was changed to the above coating liquid 4, and the coating shear rate was 39.4 (1 / s).
  • a layered product 4 was obtained in the same manner as in Example 1 except that the content was changed to).
  • a positive electrode plate 2 was obtained.
  • the thickness of the positive electrode active material layer was 37 ⁇ m.
  • a non-aqueous electrolyte secondary battery 4 was obtained in the same manner as in Example 1 except that the laminate 4 was used instead of the laminate 1 and the positive electrode plate 2 was used as the positive electrode plate.
  • Example 5 (Positive plate) A positive electrode plate was obtained in which the positive electrode mixture (LiCoO 2 / conductive agent / PVDF (weight ratio: 100/5/3)) was laminated on one surface of the positive electrode current collector (aluminum foil). A binding pressure (0.7 MPa) was applied at room temperature for 30 seconds while the positive electrode plate was wet with diethyl carbonate.
  • the positive electrode mixture LiCoO 2 / conductive agent / PVDF (weight ratio: 100/5/3)
  • a binding pressure 0.7 MPa
  • the positive electrode plate is cut so that the size of the part where the positive electrode active material layer is laminated is 45 mm ⁇ 30 mm, and the part where the positive electrode active material layer is not laminated is left on the outer periphery of the positive electrode plate so as to remain. Board 3 was obtained.
  • the thickness of the positive electrode active material layer was 38 ⁇ m.
  • a non-aqueous electrolyte secondary battery 5 was obtained in the same manner as in Example 1 except that the laminate 4 was used instead of the laminate 1 and the positive electrode plate 3 was used as the positive electrode plate.
  • Example 6 (Negative electrode plate) A negative electrode plate in which a negative electrode mixture of natural graphite / styrene-1,3-butadiene copolymer / sodium carboxymethyl cellulose (weight ratio 98/1/1) was laminated on one side of a negative electrode current collector (copper foil) It was A binding pressure (0.7 MPa) was applied for 30 seconds at room temperature while the negative electrode plate was wet with diethyl carbonate.
  • a negative electrode plate 2 was obtained.
  • the thickness of the negative electrode active material layer was 37 ⁇ m.
  • a non-aqueous electrolyte secondary battery 6 was obtained in the same manner as in Example 1 except that the laminate 4 was used instead of the laminate 1 and the negative electrode plate 2 was used as the negative electrode plate.
  • Example 7 (Negative electrode plate) A negative electrode plate was obtained in which a negative electrode mixture of artificial spherulite graphite / conductive agent / PVDF (weight ratio 85/15 / 7.5) was laminated on one surface of a negative electrode current collector (copper foil). A binding pressure (0.7 MPa) was applied for 30 seconds at room temperature while the negative electrode plate was wet with diethyl carbonate.
  • a negative electrode plate 3 was obtained.
  • the thickness of the negative electrode active material layer was 36 ⁇ m.
  • a non-aqueous electrolyte secondary battery 7 was obtained in the same manner as in Example 1 except that the laminate 4 was used instead of the laminate 1 and the negative electrode plate 3 was used as the negative electrode plate.
  • the coating liquid was prepared as follows. That is, 10 parts by weight of vinylidene fluoride-hexafluoropropylene copolymer was mixed with 90 parts by weight of inorganic filler, and the solid content in the resulting mixed liquid (inorganic filler + vinylidene fluoride-hexafluoropropylene copolymer). The solvent was mixed so that the concentration of was 40% by weight. The obtained mixed liquid was stirred and mixed by a thin film swivel type high speed mixer to obtain a uniform coating liquid 5.
  • the inorganic filler 1 used in the preparation of the porous layer (B layer) was changed to the above inorganic filler 5, the coating liquid 1 was changed to the above coating liquid 5, and the coating shear rate was 7.9 (1 / s A layered product 5 was obtained in the same manner as in Example 1 except that the content was changed to).
  • a non-aqueous electrolyte secondary battery 8 was obtained in the same manner as in Example 1 except that the laminate 5 was used instead of the laminate 1.
  • the positive electrode plate 4 was used.
  • the thickness of the positive electrode active material layer was 38 ⁇ m.
  • a non-aqueous electrolyte secondary battery 9 was obtained in the same manner as in Example 1 except that the laminate 4 was used instead of the laminate 1 and the positive electrode plate 4 was used as the positive electrode plate.
  • the negative electrode plate 4 was used.
  • the thickness of the negative electrode active material layer was 38 ⁇ m.
  • a non-aqueous electrolyte secondary battery 10 was obtained in the same manner as in Example 1 except that the laminate 4 was used instead of the laminate 1 and the negative electrode plate 4 was used as the negative electrode plate.
  • Example 2 In Table 1, two types of compounds and numerical values are described in the “inorganic filler” column of Examples 2 and 4 to 7 and Comparative Examples 2 to 3. The numerical value represents the weight part of the compound. For example, in Example 2, "Al 2 O 3 / mica 50/50" is described, which means that 50 parts by weight of Al 2 O 3 and 50 parts by weight of mica were used.
  • the non-aqueous electrolyte secondary batteries of Examples 1 to 7 have excellent discharge capacity recovery characteristics after charge / discharge cycles as compared with the non-aqueous electrolyte secondary batteries of Comparative Examples 1 to 3. I found out.
  • the number of folds until the electrode active material layer of the positive electrode plate was peeled was 130 times or more, and the number of folds until the electrode active material layer of the negative electrode plate was peeled was 1650. It is more than once, and the value represented by
  • Comparative Example 2 the number of bending times before peeling off the electrode active material layer of the positive electrode plate was less than 130 times. In Comparative Example 3, the number of times of bending until the electrode active material layer of the negative electrode plate was peeled off was less than 1650.
  • the non-aqueous electrolyte secondary battery according to an embodiment of the present invention is excellent in discharge capacity recovery characteristics after charge / discharge cycles, and thus is suitable as a battery used for personal computers, mobile phones, personal digital assistants, and the like, and a vehicle battery. Can be used for.

Abstract

The purpose of the present invention is to achieve a non-aqueous electrolyte secondary battery exhibiting excellent discharge capacity recovery characteristics after charge/discharge cycles. A non-aqueous electrolyte secondary battery according to the present invention comprises: a porous layer containing an inorganic filler and a resin; a positive electrode plate which can endure at least 130 bending events until an electrode active material layer is peeled off; and a negative electrode plate which can endure at least 1650 bending events, wherein the porous layer has a scratch test value represented by a specific equation in the range of 0.10-0.42.

Description

非水電解液二次電池Non-aqueous electrolyte secondary battery
　本発明は、非水電解液二次電池に関する。 The present invention relates to a non-aqueous electrolyte secondary battery.
　リチウム二次電池等の非水電解液二次電池は、現在、パーソナルコンピュータ、携帯電話、携帯情報端末等の機器に用いる電池として広く使用されている。 Non-aqueous electrolyte secondary batteries such as lithium secondary batteries are currently widely used as batteries for devices such as personal computers, mobile phones and personal digital assistants.
　リチウムイオン電池を搭載する機器では充電器および電池パックに多種類の電気的保護回路を設けることにより、電池を正常、安全に作動させる対策を施している。しかしながら、例えば、これら保護回路の故障または誤作動により、リチウムイオン電池が充電され続けると、発熱を伴う正負極表面での電解液の酸化還元分解、正極活物質の分解による酸素放出、さらには負極における金属リチウムの析出が起こることがある。その結果、最終的に熱暴走状態に陥ることで、場合によって電池の発火または破裂を引き起こす危険がある。 For equipment equipped with a lithium-ion battery, measures have been taken to ensure normal and safe operation of the battery by providing various types of electrical protection circuits in the charger and battery pack. However, if the lithium ion battery continues to be charged due to failure or malfunction of these protection circuits, redox decomposition of the electrolytic solution on the positive and negative electrode surfaces accompanied by heat generation, oxygen release due to decomposition of the positive electrode active material, and further negative electrode Of metallic lithium may occur. As a result, there is a risk of eventually causing a battery to ignite or explode by falling into a thermal runaway state.
　このような危険な熱暴走状態に至る前に電池を安全に停止させるため、現在ほとんどのリチウムイオン電池には、ポリオレフィンを主成分とする多孔質基材が、セパレータとして使用されている。当該ポリオレフィンを主成分とする多孔質基材は、何らかの不具合で電池内部温度が上昇すると約１３０℃～１４０℃で多孔質基材に開いている細孔が閉塞するシャットダウン機能を有する。 In order to safely stop the battery before it reaches such a dangerous thermal runaway state, most lithium-ion batteries currently use a porous base material containing polyolefin as a main component as a separator. The porous base material containing polyolefin as a main component has a shutdown function of closing pores open in the porous base material at about 130 ° C. to 140 ° C. when the battery internal temperature rises due to some trouble.
　一方、ポリオレフィンを主成分とする多孔質基材は、耐熱性が低いために、シャットダウン機能が作動する温度以上に曝されることで溶融し、その結果、電池内部で短絡が生じ、電池の発火または爆発を生じる虞があった。そこで、前記多孔質基材の耐熱性を改善する目的で、前記多孔質基材の少なくとも一面に、フィラーと、樹脂とを含む多孔質層を積層させたセパレータの開発が進められている。 On the other hand, the porous base material containing polyolefin as the main component has low heat resistance, so that it is melted by being exposed to a temperature higher than the temperature at which the shutdown function operates, resulting in a short circuit inside the battery and ignition of the battery. Or there was a risk of an explosion. Therefore, for the purpose of improving the heat resistance of the porous base material, a separator in which a porous layer containing a filler and a resin is laminated on at least one surface of the porous base material is being developed.
　そのようなセパレータの一例として、特許文献１には、微粒子としてベーマイト（板状粒子）を含有する多孔質層で形成された電池用セパレータが記載されている。 As an example of such a separator, Patent Document 1 describes a battery separator formed of a porous layer containing boehmite (plate-like particles) as fine particles.
特開２００８－４４３８号公報（２００８年１月１０日公開）Japanese Unexamined Patent Application Publication No. 2008-4438 (Published January 10, 2008)
　しかしながら、上述のような従来技術は、充放電サイクル後の電池の放電容量回復特性の観点からは改善の余地があった。 However, the above-described conventional technology has room for improvement in terms of the discharge capacity recovery characteristics of the battery after the charge / discharge cycle.
　本発明は、前記の問題点に鑑みてなされたものであり、その目的は、充放電サイクル後の電池の放電容量回復特性に優れた非水電解液二次電池を実現することにある。 The present invention has been made in view of the above problems, and an object thereof is to realize a non-aqueous electrolyte secondary battery having excellent discharge capacity recovery characteristics of a battery after a charge / discharge cycle.
　本発明の態様１に係る非水電解液二次電池は、無機フィラーと樹脂とを含む多孔質層と、ＪＩＳ　Ｐ　８１１５（１９９４）に規定されたＭＩＴ試験機法に準拠し、荷重１Ｎ、折り曲げ角度４５°にて実施した耐折試験において、電極活物質層が剥がれるまでの折り曲げ回数が１３０回以上である正極板と、前記耐折試験において、電極活物質層が剥がれるまでの折り曲げ回数が１６５０回以上である負極板と、を備え、前記多孔質層は、下記式（１）で表される値が、０．１０～０．４２の範囲にある。
｜１－Ｔ／Ｍ｜・・・（１）
（式（１）中、Ｔは、ＴＤにおける０．１Ｎの一定荷重下でのスクラッチ試験における、臨界荷重までの距離を表し、Ｍは、ＭＤにおける０．１Ｎの一定荷重下でのスクラッチ試験における、臨界荷重までの距離を表す。）
　また、本発明の態様２に係る非水電解液二次電池は、前記態様１において、前記多孔質層が、ポリオレフィン、（メタ）アクリレート系樹脂、含フッ素樹脂、ポリアミド系樹脂、ポリエステル系樹脂および水溶性ポリマーからなる群より１種以上選択される樹脂を含む。 The non-aqueous electrolyte secondary battery according to Aspect 1 of the present invention is based on a porous layer containing an inorganic filler and a resin and a MIT tester method defined in JIS P 8115 (1994). In the folding endurance test carried out at an angle of 45 °, the positive electrode plate having a bending frequency of 130 times or more before the electrode active material layer was peeled off, and in the folding endurance test, the bending frequency until the electrode active material layer was peeled off was 1650. And a negative electrode plate that is more than once, and the porous layer has a value represented by the following formula (1) in the range of 0.10 to 0.42.
| 1-T / M | ... (1)
(In Formula (1), T represents a distance to a critical load in a scratch test under a constant load of 0.1 N in TD, and M represents a scratch test under a constant load of 0.1 N in MD. , Represents the distance to the critical load.)
Further, in the non-aqueous electrolyte secondary battery according to Aspect 2 of the present invention, in the Aspect 1, the porous layer includes a polyolefin, a (meth) acrylate resin, a fluorine-containing resin, a polyamide resin, a polyester resin, and It includes a resin selected from the group consisting of water-soluble polymers.
　また、本発明の態様３に係る非水電解液二次電池は、前記態様２において、前記ポリアミド系樹脂がアラミド樹脂である。 Further, in the non-aqueous electrolyte secondary battery according to Aspect 3 of the present invention, in the Aspect 2, the polyamide resin is an aramid resin.
　また、本発明の態様４に係る非水電解液二次電池は、前記態様１～３のいずれかにおいて、前記多孔質層が、ポリオレフィン多孔質フィルムの片面または両面に積層されている。 Further, in the non-aqueous electrolyte secondary battery according to Aspect 4 of the present invention, in any one of Aspects 1 to 3, the porous layer is laminated on one side or both sides of a polyolefin porous film.
　また、本発明の態様５に係る非水電解液二次電池は、前記態様１～４のいずれかにおいて、前記正極板が、遷移金属酸化物を含み、前記負極板が、黒鉛を含む。 Further, in the non-aqueous electrolyte secondary battery according to Aspect 5 of the present invention, in any one of Aspects 1 to 4, the positive electrode plate contains a transition metal oxide and the negative electrode plate contains graphite.
　本発明の一態様によれば、充放電サイクル後の電池の放電容量回復特性に優れた非水電解液二次電池を実現できる。 According to one aspect of the present invention, a non-aqueous electrolyte secondary battery having excellent discharge capacity recovery characteristics of a battery after a charge / discharge cycle can be realized.
ＭＩＴ試験機の概略を示す模式図である。It is a schematic diagram which shows the outline of a MIT test machine. 無機フィラーを含む多孔質層における、無機フィラーの配向性が大きい場合（左図）および無機フィラーの配向性が小さい場合（右図）の、当該多孔質層の構造を表す模式図である。It is a schematic diagram showing the structure of the said porous layer when the orientation of an inorganic filler is large in the porous layer containing an inorganic filler (left figure), and when the orientation of an inorganic filler is small (right figure). スクラッチ試験における、装置およびその操作を示す図である。It is a figure which shows the apparatus and its operation in a scratch test. スクラッチ試験の結果から作成したグラフにおける、臨界荷重および臨界荷重までの距離を示した図である。It is the figure which showed the critical load and the distance to a critical load in the graph created from the result of the scratch test.
　本発明の一実施形態に関して以下に説明するが、本発明はこれに限定されるものではない。本発明は、以下に説明する各構成に限定されるものではなく、特許請求の範囲に示した範囲で種々の変更が可能であり、異なる実施形態にそれぞれ開示された技術的手段を適宜組み合わせて得られる実施形態に関しても本発明の技術的範囲に含まれる。なお、本明細書において特記しない限り、数値範囲を表す「Ａ～Ｂ」は、「Ａ以上、Ｂ以下」を意味する。 An embodiment of the present invention will be described below, but the present invention is not limited to this. The present invention is not limited to each configuration described below, various modifications are possible within the scope shown in the claims, and the technical means disclosed in different embodiments are appropriately combined. The obtained embodiments are also included in the technical scope of the present invention. Unless otherwise specified in the present specification, “A to B” representing a numerical range means “A or more and B or less”.
　本発明の一実施形態に係る非水電解液二次電池は、無機フィラーと樹脂とを含む多孔質層と、ＪＩＳ　Ｐ　８１１５（１９９４）に規定されたＭＩＴ試験機法に準拠し、荷重１Ｎ、折り曲げ角度４５°にて実施した耐折試験において、電極活物質層が剥がれるまでの折り曲げ回数が１３０回以上である正極板と、前記耐折試験において、電極活物質層が剥がれるまでの折り曲げ回数が１６５０回以上である負極板と、を備え、前記多孔質層は、下記式（１）で表される値が、０．１０～０．４２の範囲にあることを特徴とする。
｜１－Ｔ／Ｍ｜・・・（１）
（式（１）中、Ｔは、ＴＤ（Transverse Direction）における０．１Ｎの一定荷重下でのスクラッチ試験における、臨界荷重までの距離を表し、Ｍは、ＭＤ（Machine Direction）における０．１Ｎの一定荷重下でのスクラッチ試験における、臨界荷重までの距離を表す。）
　＜正極板＞
　本発明の一実施形態に係る非水電解液二次電池における正極板は、後述のように耐折試験において測定される折り曲げ回数が特定の範囲であれば特に限定されない。例えば、正極活物質層として、正極活物質、導電剤および結着剤を含む正極合剤を正極集電体上に担持したシート状の正極板が用いられる。なお、正極板は、正極集電体の両面上に正極合剤を担持してもよく、正極集電体の片面上に正極合剤を担持してもよい。 A non-aqueous electrolyte secondary battery according to an embodiment of the present invention is based on a porous layer containing an inorganic filler and a resin, a MIT tester method defined in JIS P 8115 (1994), a load of 1 N, In the folding endurance test carried out at a bending angle of 45 °, the positive electrode plate having a folding frequency of 130 times or more before the electrode active material layer was peeled off, and the folding frequency until the electrode active material layer was peeled off in the folding durability test. 1650 times or more, and the porous layer has a value represented by the following formula (1) in a range of 0.10 to 0.42.
| 1-T / M | ... (1)
(In Formula (1), T represents a distance to a critical load in a scratch test under a constant load of 0.1 N in TD (Transverse Direction), and M represents 0.1 N in MD (Machine Direction). Indicates the distance to the critical load in the scratch test under constant load.)
<Positive plate>
The positive electrode plate in the non-aqueous electrolyte secondary battery according to the embodiment of the present invention is not particularly limited as long as the number of bending times measured in the folding endurance test is within a specific range as described below. For example, as the positive electrode active material layer, a sheet-shaped positive electrode plate in which a positive electrode mixture containing a positive electrode active material, a conductive agent and a binder is carried on a positive electrode current collector is used. The positive electrode plate may carry the positive electrode mixture on both surfaces of the positive electrode current collector, or may carry the positive electrode mixture on one surface of the positive electrode current collector.
　前記正極活物質としては、例えば、リチウムイオンをドープ・脱ドープ可能な材料が挙げられる。当該材料としては、遷移金属酸化物が好ましい。遷移金属酸化物として、具体的には、例えば、Ｖ、Ｍｎ、Ｆｅ、ＣｏおよびＮｉ等の遷移金属を少なくとも１種類含んでいるリチウム複合酸化物が挙げられる。 The positive electrode active material includes, for example, a material that can be doped with lithium ions and dedoped. A transition metal oxide is preferable as the material. Specific examples of the transition metal oxide include a lithium composite oxide containing at least one transition metal such as V, Mn, Fe, Co and Ni.
　前記導電剤としては、黒鉛（天然黒鉛、人造黒鉛）、コークス類、カーボンブラック、熱分解炭素類、炭素繊維、有機高分子化合物焼成体等の炭素質材料等が挙げられる。前記導電剤は、１種類のみを用いてもよく、２種類以上を組み合わせて用いてもよい。 Examples of the conductive agent include carbonaceous materials such as graphite (natural graphite and artificial graphite), cokes, carbon black, pyrolytic carbons, carbon fibers, and organic polymer compound fired bodies. The conductive agent may be used alone or in combination of two or more kinds.
　前記結着剤としては、例えば、ポリフッ化ビニリデン、フッ化ビニリデンの共重合体、ポリテトラフルオロエチレン、テトラフルオロエチレン－ヘキサフルオロプロピレンの共重合体、テトラフルオロエチレン－パーフルオロアルキルビニルエーテルの共重合体、エチレン－テトラフルオロエチレンの共重合体、フッ化ビニリデン－ヘキサフルオロプロピレン共重合体、フッ化ビニリデン－ヘキサフルオロプロピレン－テトラフルオロエチレンの共重合体、熱可塑性ポリイミド、ポリエチレン、およびポリプロピレン等の熱可塑性樹脂、アクリル樹脂、ならびにスチレンブタジエンゴムが挙げられる。尚、結着剤は、増粘剤としての機能も有している。 Examples of the binder include polyvinylidene fluoride, vinylidene fluoride copolymer, polytetrafluoroethylene, tetrafluoroethylene-hexafluoropropylene copolymer, tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer. Thermoplastics such as ethylene-tetrafluoroethylene copolymer, vinylidene fluoride-hexafluoropropylene copolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene copolymer, thermoplastic polyimide, polyethylene and polypropylene Resins, acrylic resins, and styrene butadiene rubber are mentioned. The binder also has a function as a thickener.
　前記正極集電体としては、例えば、Ａｌ、Ｎｉ、ステンレス等の導電体が挙げられる。なかでも、薄膜に加工し易く、安価であることから、Ａｌがより好ましい。 Examples of the positive electrode current collector include conductors such as Al, Ni, and stainless steel. Among them, Al is more preferable because it is easily processed into a thin film and is inexpensive.
　＜負極板＞
　本発明の一実施形態に係る非水電解液二次電池における負極板は、後述のように耐折試験において測定される折り曲げ回数が特定の範囲であれば特に限定されない。例えば、負極活物質層として、負極活物質を含む負極合剤を負極集電体上に担持したシート状の負極が用いられる。シート状の負極板には、好ましくは、前記導電剤および前記結着剤が含まれる。なお、負極板は、負極集電体の両面上に負極合剤を担持してもよく、負極集電体の片面上に負極合剤を担持してもよい。 <Negative electrode plate>
The negative electrode plate in the non-aqueous electrolyte secondary battery according to the embodiment of the present invention is not particularly limited as long as the number of folding times measured in the folding endurance test is within a specific range as described below. For example, a sheet-shaped negative electrode in which a negative electrode mixture containing a negative electrode active material is carried on a negative electrode current collector is used as the negative electrode active material layer. The sheet-shaped negative electrode plate preferably contains the conductive agent and the binder. The negative electrode plate may carry the negative electrode mixture on both surfaces of the negative electrode current collector, or may carry the negative electrode mixture on one surface of the negative electrode current collector.
　前記負極活物質としては、例えば、リチウムイオンをドープ・脱ドープ可能な材料、リチウム金属またはリチウム合金等が挙げられる。当該材料としては、例えば、炭素質材料等が挙げられる。炭素質材料としては、黒鉛（天然黒鉛、人造黒鉛）、コークス類、カーボンブラック、および熱分解炭素類等が挙げられる。導電剤、結着剤としては、前記正極活物質層に含まれ得る導電剤、結着剤として記載したものを使用することができる。 The negative electrode active material includes, for example, a material capable of being doped / dedoped with lithium ions, lithium metal or a lithium alloy. Examples of the material include a carbonaceous material and the like. Examples of the carbonaceous material include graphite (natural graphite, artificial graphite), cokes, carbon black, and pyrolytic carbons. As the conductive agent and the binder, those described as the conductive agent and the binder which can be contained in the positive electrode active material layer can be used.
　前記負極集電体としては、例えば、Ｃｕ、Ｎｉ、ステンレス等が挙げられ、特にリチウムイオン二次電池においてはリチウムと合金を作り難く、かつ薄膜に加工し易いことから、Ｃｕがより好ましい。 Examples of the negative electrode current collector include Cu, Ni, and stainless steel. Particularly, in a lithium ion secondary battery, Cu is more preferable because it is difficult to form an alloy with lithium and is easily processed into a thin film.
　＜折り曲げ回数＞
　本発明の一実施形態における正極板および負極板は、ＪＩＳ　Ｐ　８１１５（１９９４）に規定されたＭＩＴ試験機法に準拠して実施した耐折試験において、活物質層が剥がれるまでの折り曲げ回数が特定の範囲である。前記耐折試験は、荷重１Ｎ、折り曲げ角度４５°にて実施される。非水電解液二次電池では、充放電サイクルの過程で、活物質の膨張および収縮が起こり得る。前記耐折試験により測定された、電極活物質層が剥がれるまでの折り曲げ回数が多いほど、電極活物質層内部に含まれる成分（活物質、導電剤およびバインダー）同士の密着性、および、電極活物質層と集電体との密着性が維持されやすいことを表す。それゆえ、充放電サイクルの過程での非水電解液二次電池の劣化が抑制される。 <Number of folds>
The positive electrode plate and the negative electrode plate according to one embodiment of the present invention are specified in the number of bendings until the active material layer is peeled off in a folding endurance test carried out in accordance with the MIT tester method defined in JIS P 8115 (1994). The range is. The folding endurance test is performed at a load of 1 N and a bending angle of 45 °. In the non-aqueous electrolyte secondary battery, expansion and contraction of the active material may occur during the charge / discharge cycle. The more the number of bendings until the electrode active material layer is peeled off, measured by the folding endurance test, is that the components contained in the electrode active material layer (active material, conductive agent and binder) are closely attached to each other, and the electrode activity is large. It means that the adhesion between the material layer and the current collector is easily maintained. Therefore, the deterioration of the non-aqueous electrolyte secondary battery during the charge / discharge cycle is suppressed.
　前記耐折試験において、正極板は、電極活物質層が剥がれるまでの折り曲げ回数が１３０回以上であり、１５０回以上であることが好ましい。また、前記耐折試験において、負極板は、電極活物質層が剥がれるまでの折り曲げ回数が１６５０回以上であり、１８００回以上であることが好ましく、２０００回以上であることがより好ましい。 In the folding endurance test, the positive electrode plate is bent 130 times or more, preferably 150 times or more, until the electrode active material layer is peeled off. In addition, in the folding endurance test, the negative electrode plate has a number of folding times of 1650 or more, preferably 1800 or more, and more preferably 2000 or more, before the electrode active material layer is peeled off.
　図１は、ＭＩＴ試験機法に用いられるＭＩＴ試験機の概略を示す模式図である。ｘ軸は水平方向を表し、ｙ軸は鉛直方向を表す。ＭＩＴ試験機法の概要を以下に説明する。試験片の長手方向の一端をばね荷重クランプで挟み、もう一端を折り曲げクランプで挟んで固定する。ばね荷重クランプは錘とつながっている。前記耐折試験では、この錘による荷重が１Ｎである。これにより試験片は、長手方向にテンションがかかった状態となる。この状態において、試験片の長手方向は鉛直方向と平行である。そして、折り曲げクランプを回転させることにより、試験片を折り曲げる。前記耐折試験では、この際の折り曲げ角度が４５°である。すなわち、試験片は左右に４５°に折り曲げられる。また、試験片を折り曲げる速度は、１７５往復／分である。 FIG. 1 is a schematic diagram showing an outline of the MIT test machine used in the MIT test machine method. The x-axis represents the horizontal direction and the y-axis represents the vertical direction. The outline of the MIT test machine method will be described below. One end of the test piece in the longitudinal direction is clamped with a spring-loaded clamp, and the other end is clamped with a bending clamp. The spring loaded clamp is connected to the weight. In the folding endurance test, the load by the weight is 1N. As a result, the test piece is in a state of being tensioned in the longitudinal direction. In this state, the longitudinal direction of the test piece is parallel to the vertical direction. Then, the test piece is bent by rotating the bending clamp. In the folding endurance test, the bending angle at this time is 45 °. That is, the test piece is bent left and right at 45 °. The speed of bending the test piece is 175 reciprocations / minute.
　＜正極板および負極板の製造方法＞
　シート状の正極板の製造方法としては、例えば、正極活物質、導電剤および結着剤を正極集電体上で加圧成型する方法；適当な有機溶剤を用いて正極活物質、導電剤および結着剤をペースト状にした後、当該ペーストを正極集電体に塗工し、次いで、湿潤状態で、または乾燥した後に加圧することにより、正極集電体に固着する方法等が挙げられる。 <Method for producing positive electrode plate and negative electrode plate>
Examples of the method for producing a sheet-shaped positive electrode plate include a method in which a positive electrode active material, a conductive agent, and a binder are pressure-molded on a positive electrode current collector; a positive electrode active material, a conductive agent, and Examples include a method in which the binder is made into a paste, the paste is applied to the positive electrode current collector, and then the paste is adhered to the positive electrode current collector by applying pressure in a wet state or after drying.
　同様に、シート状の負極板の製造方法としては、例えば、負極活物質を負極集電体上で加圧成型する方法；適当な有機溶剤を用いて負極活物質をペースト状にした後、当該ペーストを負極集電体に塗工し、次いで、湿潤状態で、または乾燥した後に加圧することにより、負極集電体に固着する方法等が挙げられる。前記ペーストには、好ましくは前記導電剤および前記結着剤が含まれる。 Similarly, as a method for producing a sheet-shaped negative electrode plate, for example, a method of press-molding the negative electrode active material on a negative electrode current collector; after making the negative electrode active material into a paste using an appropriate organic solvent, Examples thereof include a method of applying the paste to the negative electrode current collector and then applying pressure in a wet state or after drying to fix the negative electrode current collector. The paste preferably contains the conductive agent and the binder.
　ここで、加圧を行う時間、圧力、または加圧方法等を調整することにより、上述の折り曲げ回数を制御することができる。加圧を行う時間は、１～３６００秒が好ましく、より好ましくは１～３００秒である。加圧は、正極板または負極板を拘束することにより、行われてもよい。本明細書では、拘束による圧力を拘束圧とも称する。拘束圧は、０．０１～１０ＭＰａが好ましく、より好ましくは０．０１～５ＭＰａである。また、有機溶媒を用いて正極板または負極板を湿潤させた状態で加圧してもよい。これによって、電極活物質層内部に含まれる成分同士の密着性、および、電極活物質層と集電体との密着性が向上し得る。有機溶媒としては、例えば、カーボネート類、エーテル類、エステル類、ニトリル類、アミド類、カーバメート類および含硫黄化合物、ならびにこれらの有機溶媒にフッ素基が導入されてなる含フッ素有機溶媒等が挙げられる。 Here, the number of times of bending described above can be controlled by adjusting the time for applying pressure, the pressure, the pressing method, or the like. The pressurizing time is preferably 1 to 3600 seconds, more preferably 1 to 300 seconds. The pressurization may be performed by restraining the positive electrode plate or the negative electrode plate. In this specification, the pressure due to restraint is also referred to as restraint pressure. The binding pressure is preferably 0.01 to 10 MPa, more preferably 0.01 to 5 MPa. Further, the positive electrode plate or the negative electrode plate may be pressurized while being wetted with an organic solvent. This can improve the adhesion between the components contained in the electrode active material layer and the adhesion between the electrode active material layer and the current collector. Examples of the organic solvent include carbonates, ethers, esters, nitriles, amides, carbamates and sulfur-containing compounds, and fluorine-containing organic solvents obtained by introducing a fluorine group into these organic solvents. ..
　＜多孔質層＞
　本発明の一実施形態において、多孔質層は、非水電解液二次電池を構成する部材として、ポリオレフィン多孔質フィルムと、正極板および負極板の少なくともいずれか一方との間に配置され得る。前記多孔質層は、ポリオレフィン多孔質フィルムの片面または両面に形成され得る。或いは、前記多孔質層は、正極板および負極板の少なくともいずれか一方の活物質層上に形成され得る。或いは、前記多孔質層は、ポリオレフィン多孔質フィルムと、正極板および負極板の少なくともいずれか一方との間に、これらと接するように配置されてもよい。ポリオレフィン多孔質フィルムと正極板および負極板の少なくともいずれか一方との間に配置される多孔質層は１層でもよく２層以上であってもよい。多孔質層は、樹脂を含む絶縁性の多孔質層であることが好ましい。 <Porous layer>
In one embodiment of the present invention, the porous layer may be disposed between the polyolefin porous film and at least one of the positive electrode plate and the negative electrode plate as a member constituting the non-aqueous electrolyte secondary battery. The porous layer may be formed on one side or both sides of the polyolefin porous film. Alternatively, the porous layer may be formed on the active material layer of at least one of the positive electrode plate and the negative electrode plate. Alternatively, the porous layer may be arranged between the polyolefin porous film and at least one of the positive electrode plate and the negative electrode plate so as to be in contact with them. The porous layer disposed between the polyolefin porous film and at least one of the positive electrode plate and the negative electrode plate may be one layer or two or more layers. The porous layer is preferably an insulating porous layer containing a resin.
　ポリオレフィン多孔質フィルムの片面に多孔質層が積層される場合には、当該多孔質層は、好ましくは、ポリオレフィン多孔質フィルムにおける正極板と対向する面に積層される。より好ましくは、当該多孔質層は、正極板と接する面に積層される。 When the porous layer is laminated on one side of the polyolefin porous film, the porous layer is preferably laminated on the surface of the polyolefin porous film facing the positive electrode plate. More preferably, the porous layer is laminated on the surface in contact with the positive electrode plate.
　本発明の一実施形態における多孔質層は、無機フィラーと、樹脂とを含む。多孔質層は、内部に多数の細孔を有し、これら細孔が連結された構造となっており、一方の面から他方の面へと気体或いは液体が通過可能となった層である。また、本発明の一実施形態における多孔質層が後述する非水電解液二次電池用積層セパレータを構成する部材として使用される場合、前記多孔質層は、当該積層セパレータの最外層として、電極と接する層となり得る。 The porous layer in one embodiment of the present invention contains an inorganic filler and a resin. The porous layer has a large number of pores inside and has a structure in which these pores are connected, and is a layer through which gas or liquid can pass from one surface to the other surface. Further, when the porous layer in one embodiment of the present invention is used as a member constituting a non-aqueous electrolyte secondary battery laminated separator described below, the porous layer is an electrode as an outermost layer of the laminated separator. Can be a layer in contact with.
　本発明の一実施形態における多孔質層に含まれる樹脂は、電池の電解液に不溶であり、また、その電池の使用範囲において電気化学的に安定であることが好ましい。前記樹脂としては、具体的には、例えば、ポリオレフィン；（メタ）アクリレート系樹脂；含フッ素樹脂；ポリアミド系樹脂；ポリイミド系樹脂；ポリエステル系樹脂；ゴム類；融点またはガラス転移温度が１８０℃以上の樹脂；水溶性ポリマー；ポリカーボネート、ポリアセタール、ポリエーテルエーテルケトン等が挙げられる。 The resin contained in the porous layer in one embodiment of the present invention is preferably insoluble in the electrolytic solution of the battery and is electrochemically stable in the usage range of the battery. Specific examples of the resin include polyolefins; (meth) acrylate resins; fluorine-containing resins; polyamide resins; polyimide resins; polyester resins; rubbers; melting points or glass transition temperatures of 180 ° C. or higher. Resins; water-soluble polymers; polycarbonates, polyacetals, polyether ether ketones and the like.
　上述の樹脂のうち、ポリオレフィン、（メタ）アクリレート系樹脂、含フッ素樹脂、ポリアミド系樹脂、ポリエステル系樹脂および水溶性ポリマーが好ましい。 Among the above resins, polyolefin, (meth) acrylate resin, fluorine-containing resin, polyamide resin, polyester resin and water-soluble polymer are preferable.
　ポリオレフィンとしては、ポリエチレン、ポリプロピレン、ポリブテン、及びエチレン－プロピレン共重合体等が好ましい。 As the polyolefin, polyethylene, polypropylene, polybutene, ethylene-propylene copolymer and the like are preferable.
　含フッ素樹脂としては、ポリフッ化ビニリデン（ＰＶＤＦ）、ポリテトラフルオロエチレン、フッ化ビニリデン－ヘキサフルオロプロピレン共重合体、テトラフルオロエチレン－ヘキサフルオロプロピレン共重合体、テトラフルオロエチレン－パーフルオロアルキルビニルエーテル共重合体、フッ化ビニリデン－テトラフルオロエチレン共重合体、フッ化ビニリデン－トリフルオロエチレン共重合体、フッ化ビニリデン－トリクロロエチレン共重合体、フッ化ビニリデン－フッ化ビニル共重合体、フッ化ビニリデン－ヘキサフルオロプロピレン－テトラフルオロエチレン共重合体、及びエチレン－テトラフルオロエチレン共重合体等、並びに、前記含フッ素樹脂の中でもガラス転移温度が２３℃以下である含フッ素ゴムを挙げることができる。 Examples of the fluorine-containing resin include polyvinylidene fluoride (PVDF), polytetrafluoroethylene, vinylidene fluoride-hexafluoropropylene copolymer, tetrafluoroethylene-hexafluoropropylene copolymer, tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer Coalescence, vinylidene fluoride-tetrafluoroethylene copolymer, vinylidene fluoride-trifluoroethylene copolymer, vinylidene fluoride-trichloroethylene copolymer, vinylidene fluoride-vinyl fluoride copolymer, vinylidene fluoride-hexafluoro Examples thereof include propylene-tetrafluoroethylene copolymer, ethylene-tetrafluoroethylene copolymer and the like, and fluorine-containing rubber having a glass transition temperature of 23 ° C. or lower among the fluorine-containing resins. .
　ポリアミド系樹脂としては、芳香族ポリアミドおよび全芳香族ポリアミドなどのアラミド樹脂が好ましい。 As the polyamide resin, aramid resins such as aromatic polyamide and wholly aromatic polyamide are preferable.
　アラミド樹脂としては、具体的には、例えば、ポリ（パラフェニレンテレフタルアミド）、ポリ（メタフェニレンイソフタルアミド）、ポリ（パラベンズアミド）、ポリ（メタベンズアミド）、ポリ（４，４’－ベンズアニリドテレフタルアミド）、ポリ（パラフェニレン－４，４’－ビフェニレンジカルボン酸アミド）、ポリ（メタフェニレン－４，４’－ビフェニレンジカルボン酸アミド）、ポリ（パラフェニレン－２，６－ナフタレンジカルボン酸アミド）、ポリ（メタフェニレン－２，６－ナフタレンジカルボン酸アミド）、ポリ（２－クロロパラフェニレンテレフタルアミド）、パラフェニレンテレフタルアミド／２，６－ジクロロパラフェニレンテレフタルアミド共重合体、メタフェニレンテレフタルアミド／２，６－ジクロロパラフェニレンテレフタルアミド共重合体等が挙げられる。このうち、ポリ（パラフェニレンテレフタルアミド）がより好ましい。 Specific examples of the aramid resin include poly (paraphenylene terephthalamide), poly (metaphenylene isophthalamide), poly (parabenzamide), poly (metabenzamide), poly (4,4′-benzanilide terephthalate). Amide), poly (paraphenylene-4,4′-biphenylenedicarboxylic acid amide), poly (metaphenylene-4,4′-biphenylenedicarboxylic acid amide), poly (paraphenylene-2,6-naphthalenedicarboxylic acid amide), Poly (metaphenylene-2,6-naphthalenedicarboxylic acid amide), poly (2-chloroparaphenylene terephthalamide), paraphenylene terephthalamide / 2,6-dichloroparaphenylene terephthalamide copolymer, metaphenylene terephthalamide / 2 , 6-diclosure Paraphenylene terephthalamide copolymer and the like. Of these, poly (paraphenylene terephthalamide) is more preferable.
　ポリエステル系樹脂としては、ポリアリレートなどの芳香族ポリエステルおよび液晶ポリエステルが好ましい。 As the polyester resin, aromatic polyester such as polyarylate and liquid crystal polyester are preferable.
　ゴム類としては、スチレン－ブタジエン共重合体およびその水素化物、メタクリル酸エステル共重合体、アクリロニトリル－アクリル酸エステル共重合体、スチレン－アクリル酸エステル共重合体、エチレンプロピレンラバー、ポリ酢酸ビニル等を挙げることができる。 Examples of rubbers include styrene-butadiene copolymer and its hydride, methacrylic acid ester copolymer, acrylonitrile-acrylic acid ester copolymer, styrene-acrylic acid ester copolymer, ethylene propylene rubber, polyvinyl acetate and the like. Can be mentioned.
　融点又はガラス転移温度が１８０℃以上の樹脂としては、ポリフェニレンエーテル、ポリスルホン、ポリエーテルスルホン、ポリフェニレンスルフィド、ポリエーテルイミド、ポリアミドイミド、ポリエーテルアミド等を挙げることができる。 Examples of the resin having a melting point or glass transition temperature of 180 ° C. or higher include polyphenylene ether, polysulfone, polyether sulfone, polyphenylene sulfide, polyetherimide, polyamideimide, and polyetheramide.
　水溶性ポリマーとしては、ポリビニルアルコール、ポリエチレングリコール、セルロースエーテル、アルギン酸ナトリウム、ポリアクリル酸、ポリアクリルアミド、ポリメタクリル酸等を挙げることができる。 Examples of water-soluble polymers include polyvinyl alcohol, polyethylene glycol, cellulose ether, sodium alginate, polyacrylic acid, polyacrylamide, polymethacrylic acid and the like.
　なお、本発明の一実施形態における多孔質層に含まれる樹脂は、１種類でもよく、２種類以上の樹脂の混合物でもよい。 The resin contained in the porous layer in the embodiment of the present invention may be one kind or a mixture of two or more kinds.
　前記樹脂の中でも、多孔質層が正極板に対向して配置される場合には、電池作動時に酸化劣化が生じたとしても非水電解液二次電池のレート特性および抵抗特性等の各種性能を維持し易いため、含フッ素樹脂が好ましい。 Among the resins, when the porous layer is arranged to face the positive electrode plate, various performances such as rate characteristics and resistance characteristics of the non-aqueous electrolyte secondary battery can be obtained even if oxidative deterioration occurs during battery operation. A fluorine-containing resin is preferable because it can be easily maintained.
　本発明の一実施形態における多孔質層は、無機フィラーを含む。その含有量の下限値は、前記フィラーと、本発明の一実施形態における多孔質層を構成する樹脂との総重量に対して、５０重量％以上であることが好ましく、７０重量％以上であることがより好ましく、９０重量％以上であることがさらに好ましい。一方、本発明の一実施形態における多孔質層における、無機フィラーの含有量の上限値は、９９重量％以下であることが好ましく、９８重量％以下であることがより好ましい。前記フィラーの含有量が、５０重量％以上であることが耐熱性の観点から好ましく、前記フィラーの含有量が、９９重量％以下であることがフィラー間の密着性の観点から好ましい。無機フィラーを含有することで、前記多孔質層を含むセパレータの滑り性および耐熱性を向上し得る。無機フィラーとしては、非水電解液に安定であり、かつ、電気化学的に安定なフィラーであれば特に限定されない。電池の安全性を確保する観点からは、耐熱温度が１５０℃以上のフィラーが好ましい。 The porous layer in one embodiment of the present invention contains an inorganic filler. The lower limit of the content is preferably 50% by weight or more and 70% by weight or more based on the total weight of the filler and the resin constituting the porous layer in the embodiment of the present invention. More preferably, it is more preferably 90% by weight or more. On the other hand, the upper limit of the content of the inorganic filler in the porous layer in the embodiment of the present invention is preferably 99% by weight or less, and more preferably 98% by weight or less. The content of the filler is preferably 50% by weight or more from the viewpoint of heat resistance, and the content of the filler is preferably 99% by weight or less from the viewpoint of adhesion between the fillers. By containing the inorganic filler, the slipperiness and heat resistance of the separator including the porous layer can be improved. The inorganic filler is not particularly limited as long as it is a filler that is stable in a non-aqueous electrolytic solution and is electrochemically stable. From the viewpoint of ensuring the safety of the battery, a filler having a heat resistant temperature of 150 ° C. or higher is preferable.
　前記無機フィラーは、特に限定されないが、通常、絶縁性フィラーである。前記無機フィラーは、好ましくは、アルミニウム元素、亜鉛元素、カルシウム元素、ジルコニウム元素、ケイ素元素、マグネシウム元素、バリウム元素、およびホウ素元素からなる群から選ばれる少なくとも１種の元素を含む無機物であり、好ましくはアルミニウム元素を含む無機物である。また、無機フィラーは、好ましくは前記金属元素の酸化物を含む。 The inorganic filler is not particularly limited, but is usually an insulating filler. The inorganic filler is preferably an inorganic material containing at least one element selected from the group consisting of aluminum element, zinc element, calcium element, zirconium element, silicon element, magnesium element, barium element, and boron element, and preferably Is an inorganic substance containing an aluminum element. Further, the inorganic filler preferably contains an oxide of the metal element.
　具体的には、無機フィラーとして、チタン酸化物、アルミナ（Ａｌ２Ｏ３）、酸化亜鉛（ＺｎＯ）、酸化カルシウム（ＣａＯ）、酸化ジルコニア（ＺｒＯ２）、シリカ、マグネシア、酸化バリウム、酸化ホウ素、マイカ、ワラストナイト、アタパルジャイト、ベーマイト（アルミナ１水和物）などを挙げることができる。前記無機フィラーとしては、１種類のフィラーを単独で使用してもよく、２種類以上のフィラーを組み合わせて使用してもよい。 Specifically, as the inorganic filler, titanium oxide, alumina (Al 2 O 3 ), zinc oxide (ZnO), calcium oxide (CaO), zirconia oxide (ZrO 2 ), silica, magnesia, barium oxide, boron oxide, Examples thereof include mica, wollastonite, attapulgite, and boehmite (alumina monohydrate). As the inorganic filler, one kind of filler may be used alone, or two or more kinds of filler may be used in combination.
　本発明の一実施形態における多孔質層における無機フィラーは、アルミナおよび板状フィラーを含むことが好ましい。前記板状フィラーとしては、上で挙げた金属元素の酸化物のうち、例えば、酸化亜鉛（ＺｎＯ）、マイカおよびベーマイトからなる群より選ばれる１以上のフィラーを挙げることができる。 The inorganic filler in the porous layer in one embodiment of the present invention preferably contains alumina and a plate-like filler. Examples of the plate-like filler include one or more fillers selected from the group consisting of zinc oxide (ZnO), mica, and boehmite among the oxides of the metal elements listed above.
　前記無機フィラーの体積平均粒子径は、良好な接着性と滑り性の確保、および積層体の成形性の観点から、０．０１μｍ～１０μｍの範囲であることが好ましい。その下限値としては０．０５μｍ以上がより好ましく、０．１μｍ以上がさらに好ましい。その上限値としては５μｍ以下がより好ましく、１μｍ以下がさらに好ましい。 The volume average particle size of the inorganic filler is preferably in the range of 0.01 μm to 10 μm from the viewpoint of ensuring good adhesiveness and slipperiness, and moldability of the laminate. The lower limit value is more preferably 0.05 μm or more, further preferably 0.1 μm or more. The upper limit value is more preferably 5 μm or less, further preferably 1 μm or less.
　前記無機フィラーの形状は、任意であり、特に限定されない。前記無機フィラーの形状は、粒子状であり得、例えば、球形状；楕円形状；板状；棒状；不定形状；繊維状；ピーナッツ状および／またはテトラポット状のように球状または柱状の単一粒子が熱融着した形状；の何れでもよい。電池の短絡防止の観点から、前記無機フィラーは、板状の粒子、および／または、凝集していない一次粒子であることが好ましい。また、イオン透過の観点からは、前記無機フィラーの形状は、多孔質中の粒子が最密充填され難く、粒子間に空隙が形成され易い、瘤、へこみ、くびれ、隆起もしくは膨らみを有する、樹枝状、珊瑚状、もしくは房（ふさ）状などの不定形状；繊維状；ピーナッツ状および／またはテトラポット状のように単一粒子が熱融着した形状であることが好ましい。前記無機フィラーの形状は、ピーナッツ状および／またはテトラポット状のように球状または柱状の単一粒子が熱融着した形状であることが特に好ましい。 The shape of the inorganic filler is arbitrary and is not particularly limited. The shape of the inorganic filler may be a particle shape, for example, a spherical shape; an elliptical shape; a plate shape; a rod shape; an indefinite shape; a fibrous shape; a spherical or columnar single particle such as a peanut shape and / or a tetrapot shape. The shape may be any of the above. From the viewpoint of preventing a short circuit in the battery, the inorganic filler is preferably plate-like particles and / or non-aggregated primary particles. Further, from the viewpoint of ion permeation, the shape of the inorganic filler is such that the particles in the porous material are difficult to be most closely packed, voids are easily formed between the particles, bumps, dents, constrictions, ridges or bulges, and dendritic It is preferable that a single particle is heat-fused such as an indeterminate shape such as a shape, a coral shape, or a tuft shape; a fibrous shape; a peanut shape and / or a tetrapot shape. The shape of the inorganic filler is particularly preferably a shape in which spherical or columnar single particles such as peanut-shaped and / or tetrapot-shaped particles are heat-sealed.
　フィラーは、多孔質層の表面に微細な凹凸を形成することで滑り性を向上させ得る。フィラーが板状の粒子および／または凝集していない一次粒子である場合には、フィラーによって多孔質層の表面に形成される凹凸がより微細になり、多孔質層と電極との接着性がより良好となる。 The filler can improve slipperiness by forming fine irregularities on the surface of the porous layer. When the filler is a plate-like particle and / or a primary particle that is not aggregated, the unevenness formed on the surface of the porous layer by the filler becomes finer, and the adhesiveness between the porous layer and the electrode is further improved. It will be good.
　本発明の一実施形態における多孔質層に含まれる、無機フィラーを構成する金属酸化物の酸素原子質量百分率は、１０％～５０％であることが好ましく、２０％～５０％であることがより好ましい。本明細書において、「酸素原子質量百分率」とは、金属酸化物全体の総質量に対する、当該金属酸化物中の酸素原子の質量の比を百分率で表したものを意味する。例えば、酸化亜鉛の場合、亜鉛の原子量：６５．４、酸素の原子量：１６.０より酸化亜鉛（ＺｎＯ）の分子量が６５．４＋１６．０＝８１．４であることから、酸化亜鉛中の酸素原子質量百分率は１６．０/８１．４×１００＝２０（％）である。 The oxygen atom mass percentage of the metal oxide constituting the inorganic filler contained in the porous layer in one embodiment of the present invention is preferably 10% to 50%, more preferably 20% to 50%. preferable. In the present specification, the "oxygen atom mass percentage" means the ratio of the mass of oxygen atoms in the metal oxide to the total mass of the entire metal oxide, expressed as a percentage. For example, in the case of zinc oxide, since the atomic weight of zinc is 65.4 and the atomic weight of oxygen is 16.0, the molecular weight of zinc oxide (ZnO) is 65.4 + 16.0 = 81.4. The atomic mass percentage is 16.0 / 81.4 × 100 = 20 (%).
　前記金属酸化物の酸素原子質量百分率が上述の範囲であれば、後述する多孔質層の製造方法にて使用する塗工液中の溶媒または分散媒と、前記無機フィラーとの親和性を好適に保ち、前記無機フィラー間を適切な距離に保つことができる。これにより、塗工液の分散性を良好にすることができ、その結果、上述の式（１）を適切な規定範囲に制御することができる。 When the oxygen atom mass percentage of the metal oxide is in the above range, the affinity between the solvent or the dispersion medium in the coating liquid used in the method for producing a porous layer described later and the inorganic filler is preferably adjusted. It is possible to maintain the distance between the above-mentioned inorganic fillers at an appropriate distance. As a result, the dispersibility of the coating liquid can be improved, and as a result, the above formula (1) can be controlled within an appropriate specified range.
　本発明の一実施形態における多孔質層は、上述の無機フィラーおよび樹脂以外のその他の成分を含んでいてもよい。前記その他の成分としては、例えば、界面活性剤、ワックス、バインダー樹脂などを挙げることができる。また、前記その他の成分の含有量は、多孔質層全体の重量に対して、０重量％～５０重量％であることが好ましい。 The porous layer in one embodiment of the present invention may contain other components than the above-mentioned inorganic filler and resin. Examples of the other components include surfactants, waxes and binder resins. The content of the other components is preferably 0% by weight to 50% by weight based on the weight of the entire porous layer.
　本発明の一実施形態における多孔質層の平均膜厚は、電極との接着性および高エネルギー密度を確保する観点から、多孔質層一層当たり、０．５μｍ～１０μｍの範囲であることが好ましく、１μｍ～５μｍの範囲であることがより好ましい。 The average film thickness of the porous layer in one embodiment of the present invention is preferably in the range of 0.5 μm to 10 μm per one layer of the porous layer from the viewpoint of ensuring adhesiveness to the electrode and high energy density. More preferably, it is in the range of 1 μm to 5 μm.
　多孔質層の単位面積当たりの目付は、多孔質層の強度、膜厚、重量およびハンドリング性を考慮して適宜決定することができる。多孔質層の単位面積当たりの目付は、多孔質層一層当たり、０．５～２０ｇ／ｍ２であることが好ましく、０．５～１０ｇ／ｍ２であることがより好ましい。 The basis weight per unit area of the porous layer can be appropriately determined in consideration of the strength, film thickness, weight and handling property of the porous layer. The basis weight per unit area of the porous layer is preferably 0.5 to 20 g / m 2 and more preferably 0.5 to 10 g / m 2 per porous layer.
　多孔質層の単位面積当たりの目付をこれらの数値範囲とすることにより、非水電解液二次電池の重量エネルギー密度および体積エネルギー密度を高くすることができる。多孔質層の目付が前記範囲を超える場合には、非水電解液二次電池が重くなる傾向がある。 By setting the basis weight per unit area of the porous layer within these numerical ranges, the weight energy density and volume energy density of the non-aqueous electrolyte secondary battery can be increased. When the basis weight of the porous layer exceeds the above range, the non-aqueous electrolyte secondary battery tends to be heavy.
　多孔質層の空隙率は、充分なイオン透過性を得ることができるように、２０～９０体積％であることが好ましく、３０～８０体積％であることがより好ましい。また、多孔質層が有する細孔の孔径は、１．０μｍ以下であることが好ましく、０．５μｍ以下であることがより好ましい。細孔の孔径をこれらのサイズとすることにより、非水電解液二次電池は、充分なイオン透過性を得ることができる。 The porosity of the porous layer is preferably 20 to 90% by volume, and more preferably 30 to 80% by volume so that sufficient ion permeability can be obtained. The pore size of the pores of the porous layer is preferably 1.0 μm or less, more preferably 0.5 μm or less. By setting the pore diameters to these sizes, the non-aqueous electrolyte secondary battery can obtain sufficient ion permeability.
　＜多孔質層表面のＴ／Ｍ比＞
　本発明の一実施形態における多孔質層は、以下の式（１）で表される値が、０．１０～０．４２の範囲であることが好ましく、０．１０～０．３０の範囲であることがより好ましい。 <T / M ratio of porous layer surface>
In the porous layer according to one embodiment of the present invention, the value represented by the following formula (1) is preferably in the range of 0.10 to 0.42, and in the range of 0.10 to 0.30. More preferably.
　｜１－Ｔ／Ｍ｜・・・（１）
　（式（１）中、Ｔは、ＴＤにおける０．１Ｎの一定荷重下でのスクラッチ試験における、臨界荷重までの距離を表し、Ｍは、ＭＤにおける０．１Ｎの一定荷重下でのスクラッチ試験における、臨界荷重までの距離を表す。）
　上述のスクラッチ試験により測定された、ＴＤにおける臨界荷重までの距離（Ｔ）と、ＭＤにおける臨界荷重までの距離（Ｍ）との割合は、多孔質層における無機フィラーの配向性を表す指標である。ここで、前記配向性が高い場合（異方性）と、前記配向性が低い場合（等方性）の、多孔質層における無機フィラーの様態の模式図を図２に示す。図２の左図が、無機フィラーを含む多孔質層における、無機フィラーの配向性が大きく異方性を示す場合の当該多孔質層の構造を表す模式図であり、図２の右図が、無機フィラーの配向性が小さく等方性を示す場合の当該多孔質層の構造を表す模式図である。 | 1-T / M | ... (1)
(In Formula (1), T represents a distance to a critical load in a scratch test under a constant load of 0.1 N in TD, and M represents a scratch test under a constant load of 0.1 N in MD. , Represents the distance to the critical load.)
The ratio of the distance (T) to the critical load in TD and the distance (M) to the critical load in MD measured by the above scratch test is an index showing the orientation of the inorganic filler in the porous layer. .. Here, FIG. 2 shows a schematic diagram of the state of the inorganic filler in the porous layer when the orientation is high (anisotropic) and when the orientation is low (isotropic). The left view of FIG. 2 is a schematic view showing the structure of the porous layer containing an inorganic filler, in which the orientation of the inorganic filler is large and exhibits anisotropy, and the right view of FIG. It is a schematic diagram showing the structure of the said porous layer in case the orientation of an inorganic filler is small and it shows isotropic property.
　上記式（１）にて表される値は、スクラッチ試験における臨界荷重までの距離の異方性を示す値であり、その値がゼロに近いほど、上記臨界荷重までの距離が等方性であることを示す。以下、式（１）にて表される値を単に「式（１）」とも称する。 The value represented by the above formula (1) is a value indicating the anisotropy of the distance to the critical load in the scratch test. The closer the value is to zero, the more isotropic the distance to the critical load is. Indicates that there is. Hereinafter, the value represented by the formula (1) is also simply referred to as “formula (1)”.
　本発明における「スクラッチ試験」とは、図３に示すように、圧子に一定の荷重をかけ、測定対象の多孔膜の表層を厚み方向に圧縮変形させた状態で水平方向に多孔膜を移動させたときの、ある圧子移動距離における発生応力を測定する試験である。多孔膜の表層を厚み方向に圧縮変形させた状態とは、すなわち、多孔膜に圧子を押し込んだ状態である。当該試験は、具体的には、以下に示す方法にて実施される：
（１）測定対象の多孔質層を多孔質基材に積層することにより得た積層多孔質フィルムである積層体を２０ｍｍ×６０ｍｍに裁断する。その後、当該裁断した積層体３を、基板２である３０ｍｍ×７０ｍｍのガラス製プレパラート上に水性糊にて貼合し、２５℃の温度下にて一昼夜乾燥させることにより、試験用サンプルを作製する。なお、上記貼合のときは、積層体とガラス製プレパラートとの間に気泡が入らないようにする。
（２）工程（１）にて作製された試験用サンプルを、マイクロスクラッチ試験装置に設置する。当該試験装置におけるダイヤモンド圧子１によって当該試験用サンプル上に０．１Ｎの大きさの垂直荷重をかけたままの状態にて、当該試験装置におけるテーブルを積層体のＴＤに向けて、５ｍｍ／ｍｉｎの速さにて、１０ｍｍの距離を移動させる。その間の、上記ダイヤモンド圧子と当該試験用サンプルとの間に発生する応力である摩擦力を測定する。
（３）工程（２）にて測定された応力の変位と、上記テーブルの移動距離との関係を示す曲線グラフを作成し、当該曲線グラフから、図４に示すように、ＴＤにおける、臨界荷重値および、臨界荷重に至るまでの距離を算出する。
（４）上記テーブルの移動方向をＭＤに変更して、上述の工程（１）～（３）を繰り返して行い、ＭＤにおける、臨界荷重値および、臨界荷重に至るまでの距離を算出する。 The "scratch test" in the present invention means, as shown in FIG. 3, a constant load is applied to the indenter, and the porous membrane is moved horizontally while the surface layer of the porous membrane to be measured is compressed and deformed in the thickness direction. This is a test for measuring the stress generated at a certain indenter movement distance when the pressure is applied. The state in which the surface layer of the porous membrane is compressed and deformed in the thickness direction is the state in which the indenter is pushed into the porous membrane. The test is specifically carried out by the following method:
(1) A laminate, which is a laminated porous film obtained by laminating a measurement target porous layer on a porous substrate, is cut into 20 mm × 60 mm. Then, the cut laminated body 3 is pasted on a 30 mm × 70 mm glass preparation, which is the substrate 2, with an aqueous paste, and dried at 25 ° C. for 24 hours to prepare a test sample. .. In addition, at the time of the above-mentioned bonding, bubbles are prevented from entering between the laminated body and the glass slide.
(2) The test sample prepared in the step (1) is installed in a micro scratch test device. With the diamond indenter 1 in the test apparatus, while the vertical load of 0.1 N is applied to the test sample, the table in the test apparatus is directed toward the TD of the laminated body at 5 mm / min. At speed, move a distance of 10 mm. During that time, a frictional force, which is a stress generated between the diamond indenter and the test sample, is measured.
(3) A curve graph showing the relationship between the displacement of the stress measured in the step (2) and the moving distance of the table is created, and from the curve graph, as shown in FIG. Calculate the value and the distance to reach the critical load.
(4) The moving direction of the table is changed to MD, and the above steps (1) to (3) are repeated to calculate the critical load value and the distance to reach the critical load in MD.
　なお、上記スクラッチ試験における、上述した条件以外の測定条件等に関しては、ＪＩＳ　Ｒ　３２５５に記載の方法と同様の条件にて実施される。 Note that the measurement conditions other than the above-mentioned conditions in the scratch test will be performed under the same conditions as the method described in JIS R3255.
　上記スクラッチ試験にて算出される臨界荷重値までの距離は、（ａ）積層多孔質フィルム表層の塑性変形容易性の指標、（ｂ）測定面と反対の面へのせん断応力の伝達性の指標となる。上記臨界荷重値までの距離が長いことは、測定対象の積層多孔質フィルムにおいて、（ａ’）表層部が塑性変形し難く、（ｂ’）測定面と反対の面へのせん断応力の伝達性が低いこと、すなわち応力が伝わり難いことを示す。 The distance to the critical load value calculated by the scratch test is (a) an index of plastic deformation easiness of the surface of the laminated porous film, (b) an index of transmissibility of shear stress to the surface opposite to the measurement surface. Becomes The long distance to the critical load value means that in the laminated porous film to be measured, (a ') the surface layer portion is less likely to be plastically deformed, and (b') the transmission of shear stress to the surface opposite to the measurement surface. Is low, that is, it is difficult for stress to be transmitted.
　なお、ＴＤ方向、ＭＤ方向における臨界荷重までの距離は、以下に示す積層多孔質フィルムの構造因子に強く影響を受けると考えられる。
（ｉ）積層多孔質フィルムにおけるＭＤへの樹脂の配向状態
（ｉｉ）積層多孔質フィルムにおけるＴＤへの樹脂の配向状態
（ｉｉｉ）積層多孔質フィルムの厚み方向におけるＭＤ方向、ＴＤ方向に配向した樹脂の接触状態
　上述の式（１）が０．４２より大きい場合には、多孔質層内部構造の異方性が過度に高い構造となるため、多孔質層内部のイオン透過流路長が長くなる。その結果、前記多孔質層を組み込んだ非水電解液二次電池において、多孔質層のイオン透過抵抗が増加し、当該非水電解液二次電池におけるセパレータの抵抗が増加する。一方、上述の式（１）が０．１０未満である場合には、多孔質層の構造が、過度に高い等方性を有する構造となっていると考えられる。多孔質層の構造が過度に高い等方性を有するときには、当該多孔質層を組み込んだ非水電解液二次電池において、電池作動時の多孔質層の電解液受入能力が過度に高くなる傾向がある。その結果、多孔質層と接し、当該多孔質層へ電解液を供給するセパレータ基材および電極の電解液供給能力が非水電解液二次電池全体の電解液の流れを律速することになる。結果として、当該非水電解液二次電池におけるセパレータの抵抗が増加する。 It is considered that the distance to the critical load in the TD direction and the MD direction is strongly influenced by the following structural factors of the laminated porous film.
(I) Orientation state of resin to MD in laminated porous film (ii) Orientation state of resin to TD in laminated porous film (iii) Resin oriented in MD direction and TD direction in thickness direction of laminated porous film When the above equation (1) is larger than 0.42, the anisotropy of the internal structure of the porous layer becomes excessively high, and the ion permeation flow path length inside the porous layer becomes long. .. As a result, in the non-aqueous electrolyte secondary battery incorporating the porous layer, the ion permeation resistance of the porous layer increases, and the resistance of the separator in the non-aqueous electrolyte secondary battery increases. On the other hand, when the above formula (1) is less than 0.10, it is considered that the structure of the porous layer is a structure having an excessively high isotropic property. When the structure of the porous layer has an excessively high isotropic property, in a non-aqueous electrolyte secondary battery incorporating the porous layer, the electrolyte receiving ability of the porous layer during battery operation tends to be excessively high. There is. As a result, the electrolyte solution supply capabilities of the separator base material and the electrode that are in contact with the porous layer and supply the electrolyte solution to the porous layer will control the flow rate of the electrolyte solution of the entire non-aqueous electrolyte secondary battery. As a result, the resistance of the separator in the non-aqueous electrolyte secondary battery increases.
　＜中心粒径（Ｄ５０）＞
　本発明の一実施形態における多孔質層は、無機フィラーの中心粒径（Ｄ５０）が０．１μｍ～１１μｍの範囲であることが好ましく、０．１μｍ～１０μｍの範囲であることがより好ましく、０．１μｍ～５μｍの範囲であることがさらに好ましく、０．５μｍであることが特に好ましい。 <Center particle size (D50)>
In the porous layer according to one embodiment of the present invention, the median particle diameter (D50) of the inorganic filler is preferably in the range of 0.1 μm to 11 μm, more preferably in the range of 0.1 μm to 10 μm, and 0 The range is more preferably from 1 μm to 5 μm, and particularly preferably 0.5 μm.
　無機フィラーの中心粒径を測定する方法は、特に限定されないが、例えば、実施例に記載の方法で測定される。 The method for measuring the median particle diameter of the inorganic filler is not particularly limited, but for example, it is measured by the method described in the examples.
　無機フィラーの中心粒径が１１μｍより大きい場合には、耐熱層の膜厚が増加してムラが発生するため、多孔質層のイオン透過にもムラが生じることとなる。その結果、前記多孔質層を組み込んだ非水電解液二次電池におけるセパレータの抵抗が増加する傾向がある。一方、無機フィラーの中心粒径が０．１μｍ未満である場合には、無機フィラーを含む塗工液の粘度が高くなるため、ダイラタンシー性を発現するおそれがある。その結果、塗工液は塗工性能不良となり、多孔質層への塗工ムラが発生することがある。また、無機フィラーの中心粒径が小さいため、無機フィラーを結着するために要するバインダー量が増加する。その結果、前記多孔質層を組み込んだ非水電解液二次電池において、多孔質層のイオン透過抵抗が増加し、当該非水電解液二次電池におけるセパレータの抵抗が増加する。 If the center particle size of the inorganic filler is larger than 11 μm, the film thickness of the heat-resistant layer increases and unevenness occurs, resulting in unevenness in ion permeation of the porous layer. As a result, the resistance of the separator in the non-aqueous electrolyte secondary battery incorporating the porous layer tends to increase. On the other hand, when the median particle diameter of the inorganic filler is less than 0.1 μm, the viscosity of the coating liquid containing the inorganic filler becomes high, which may cause dilatancy. As a result, the coating liquid may have poor coating performance and uneven coating on the porous layer may occur. Moreover, since the central particle diameter of the inorganic filler is small, the amount of binder required to bind the inorganic filler increases. As a result, in the non-aqueous electrolyte secondary battery incorporating the porous layer, the ion permeation resistance of the porous layer increases, and the resistance of the separator in the non-aqueous electrolyte secondary battery increases.
　＜ＢＥＴ比表面積＞
　本発明の一実施形態における多孔質層は、無機フィラーの単位面積当たりのＢＥＴ比表面積が１００ｍ２／ｇ以下であることが好ましく、５０ｍ２／ｇ以下であることがより好ましく、１０ｍ２／ｇ以下であってもよい。 <BET specific surface area>
In the porous layer according to one embodiment of the present invention, the BET specific surface area per unit area of the inorganic filler is preferably 100 m 2 / g or less, more preferably 50 m 2 / g or less, and 10 m 2 / g. It may be the following.
　無機フィラーの単位面積当たりのＢＥＴ比表面積を測定する方法は、特に限定されないが、例えば、以下の（１）～（３）に示す工程からなる方法を挙げることができる。
（１）８０℃で８時間の真空乾燥により、フィラーの前処理を行う工程。
（２）定容法により、窒素による吸着脱離等温線を測定する工程。
（３）ＢＥＴ法により、フィラーの比表面積を算出する工程。 The method for measuring the BET specific surface area per unit area of the inorganic filler is not particularly limited, and examples thereof include a method including the steps (1) to (3) below.
(1) A step of performing a pretreatment of the filler by vacuum drying at 80 ° C. for 8 hours.
(2) A step of measuring an adsorption-desorption isotherm by nitrogen by a constant volume method.
(3) A step of calculating the specific surface area of the filler by the BET method.
　なお、フィラーの比表面積の測定において、前処理を行う装置および測定装置は、特に限定されないが、例えば、前処理を行う装置としてＢＥＬＰＲＥＰ－ｖａｃＩＩ（マイクロトラック・ベル株式会社製）を、測定装置としてＢＥＬＳＯＲＰ－ｍｉｎｉ（マイクロトラック・ベル株式会社製）を使用することができる。 In the measurement of the specific surface area of the filler, the pretreatment device and the measurement device are not particularly limited. For example, BELPREP-vacII (manufactured by Microtrac Bell Co., Ltd.) is used as the pretreatment device. BELSORP-mini (manufactured by Microtrac Bell Co., Ltd.) can be used.
　また、フィラーの比表面積を測定する際の測定条件は、特に限定されることなく、当業者により適宜設定され得る。 Further, the measurement conditions for measuring the specific surface area of the filler are not particularly limited and can be appropriately set by those skilled in the art.
　無機フィラーの単位面積当たりのＢＥＴ比表面積が１００ｍ２／ｇより大きい場合には、ＢＥＴ比表面積の増大によりフィラー給油性が増大し、それに伴い多孔質層の塗工液としての性状が低下し、塗工性不良となるおそれがある。その結果、前記多孔質層を組み込んだ非水電解液二次電池におけるセパレータの抵抗が高くなる傾向がある。 When the BET specific surface area per unit area of the inorganic filler is larger than 100 m 2 / g, the filler oiling property is increased due to the increase in the BET specific surface area, and accordingly, the properties of the porous layer as a coating liquid are decreased, There is a risk of poor coatability. As a result, the resistance of the separator in the non-aqueous electrolyte secondary battery incorporating the porous layer tends to increase.
　＜多孔質層の製造方法＞
　本発明の一実施形態における多孔質層の製造方法としては、特に限定されないが、例えば、基材上に、以下に示す工程（１）～（３）の何れかの１つの工程を用いて、前記無機フィラーと、前記樹脂とを含む多孔質層を形成する方法を挙げることができる。以下に示す工程（２）および工程（３）の場合においては、前記樹脂を析出させた後にさらに乾燥させ、溶媒を除去することによって、多孔質層が製造され得る。工程（１）～（３）における塗工液は、前記無機フィラーが分散しており、かつ、前記樹脂が溶解している状態であってもよい。なお、前記溶媒は、樹脂を溶解させる溶媒であるとともに、樹脂または無機フィラーを分散させる分散媒であるとも言える。
（１）前記無機フィラーおよび前記樹脂を含む塗工液を、基材上に塗工し、前記塗工液中の溶媒を乾燥除去することによって多孔質層を形成させる工程。
（２）前記無機フィラーおよび前記樹脂を含む塗工液を、前記基材の表面に塗工した後、その基材を前記樹脂に対して貧溶媒である、析出溶媒に浸漬することによって、前記樹脂を析出させ、多孔質層を形成する工程。
（３）前記無機フィラーおよび前記樹脂を含む塗工液を、前記基材の表面に塗工した後、低沸点有機酸を用いて、前記塗工液の液性を酸性にすることによって、前記樹脂を析出させ、多孔質層を形成する工程。 <Method for producing porous layer>
The method for producing the porous layer according to the embodiment of the present invention is not particularly limited, but for example, one of the following steps (1) to (3) may be used on the substrate, A method of forming a porous layer containing the inorganic filler and the resin can be mentioned. In the case of the step (2) and the step (3) shown below, the porous layer can be produced by depositing the resin and then drying it to remove the solvent. The coating liquid in steps (1) to (3) may be in a state in which the inorganic filler is dispersed and the resin is dissolved. The solvent can be said to be a solvent for dissolving the resin and a dispersion medium for dispersing the resin or the inorganic filler.
(1) A step of forming a porous layer by applying a coating liquid containing the inorganic filler and the resin onto a substrate and drying and removing the solvent in the coating liquid.
(2) After applying a coating liquid containing the inorganic filler and the resin on the surface of the base material, the base material is immersed in a deposition solvent that is a poor solvent for the resin, A step of depositing a resin to form a porous layer.
(3) After coating a coating liquid containing the inorganic filler and the resin on the surface of the base material, the liquid property of the coating liquid is made acidic by using a low-boiling organic acid, A step of depositing a resin to form a porous layer.
　前記基材には、後述するポリオレフィン多孔質フィルムの他に、その他のフィルム、正極板および負極板などを用いることができる。 In addition to the polyolefin porous film described below, other films, a positive electrode plate, a negative electrode plate, and the like can be used as the base material.
　前記溶媒は基材に悪影響を及ぼさず、前記樹脂を均一かつ安定に溶解し、前記無機フィラーを均一かつ安定に分散させる溶媒であることが好ましい。前記溶媒としては、例えば、Ｎ－メチル－２－ピロリドン、Ｎ，Ｎ－ジメチルアセトアミド、Ｎ，Ｎ－ジメチルホルムアミド、アセトンおよび水等が挙げられる。 Preferably, the solvent does not adversely affect the base material, dissolves the resin uniformly and stably, and disperses the inorganic filler uniformly and stably. Examples of the solvent include N-methyl-2-pyrrolidone, N, N-dimethylacetamide, N, N-dimethylformamide, acetone and water.
　前記析出溶媒としては、例えば、イソプロピルアルコールまたはｔ－ブチルアルコールを用いることが好ましい。 As the deposition solvent, for example, isopropyl alcohol or t-butyl alcohol is preferably used.
　前記工程（３）において、低沸点有機酸としては、例えば、パラトルエンスルホン酸、酢酸等を使用することができる。 In the step (3), as the low boiling point organic acid, for example, paratoluenesulfonic acid, acetic acid, etc. can be used.
　前記多孔質層の塗工量（すなわち、目付）は、電極または電極シートとの接着性およびイオン透過性の観点から、前記多孔質層の一層あたり、通常、固形分で０．５～２０ｇ／ｍ２であることが好ましく、０．５～１０ｇ／ｍ２であることがより好ましく、０．５ｇ／ｍ２～１．５ｇ／ｍ２の範囲であることがさらに好ましい。すなわち、得られる多孔質層の塗工量（目付）が上述の範囲となるように、前記基材上に塗布する前記塗工液の量を調節することが好ましい。 The coating amount (that is, basis weight) of the porous layer is usually 0.5 to 20 g / solid per one layer of the porous layer from the viewpoint of adhesiveness to an electrode or an electrode sheet and ion permeability. is preferably m 2, more preferably from 0.5 ~ 10g / m 2, more preferably in the range of 0.5g / m 2 ~ 1.5g / m 2. That is, it is preferable to adjust the amount of the coating liquid applied on the substrate so that the coating amount (area weight) of the obtained porous layer falls within the above range.
　本発明の一実施形態における多孔質層の配向性、すなわち、上述の式（１）を制御する方法として、以下に示すように、多孔質層の製造に使用する、無機フィラーおよび樹脂を含む塗工液の固形分濃度、ならびに塗工液を基材上に塗工する際の塗工せん断速度を調節すること等を挙げることができる。 As a method for controlling the orientation of the porous layer in one embodiment of the present invention, that is, the above formula (1), as shown below, a coating containing an inorganic filler and a resin used for producing the porous layer. Examples thereof include adjusting the solid content concentration of the working liquid, and adjusting the coating shear rate when the coating liquid is applied onto the substrate.
　前記塗工液の好適な固形分濃度は、フィラーの種類などによって変化し得るが、一般には、２０重量％より大きく４０重量％以下であることが好ましい。前記固形分濃度が上述の範囲であることは、前記塗工液の粘度を適切に保ち、その結果、上述の式（１）を適切な規定範囲に制御することができる面において好ましい。 A suitable solid content concentration of the coating liquid may vary depending on the type of filler, etc., but generally it is preferably more than 20% by weight and 40% by weight or less. It is preferable for the solid content concentration to be in the above range from the viewpoint that the viscosity of the coating liquid can be appropriately maintained and, as a result, the above formula (1) can be controlled within an appropriate prescribed range.
　前記塗工液を基材上に塗工する際の塗工せん断速度は、フィラーの種類などによって変化し得るが、一般には、２（１／ｓ）以上であることが好ましく、４（１／ｓ）～５０（１／ｓ）であることがより好ましい。 The coating shear rate at the time of applying the coating liquid on the substrate may vary depending on the type of filler, etc., but generally it is preferably 2 (1 / s) or more and 4 (1 / s). More preferably, it is from s) to 50 (1 / s).
　ここで、例えば、前記無機フィラーとして、ピーナッツ状および／またはテトラポット状のように球状または柱状の単一粒子が熱融着した形状、球形状、楕円形状、板状、棒状、または、不定形状の形状を有する無機フィラーを用いた場合、前記塗工せん断速度を大きくすると、高せん断力が無機フィラーにかかるため、異方性が高くなる傾向がある。一方、前記塗工せん断速度を小さくするとせん断力が無機フィラーにかからないため、等方的に配向する傾向がある。 Here, for example, as the inorganic filler, a shape in which spherical or columnar single particles such as peanut-shaped and / or tetrapot-shaped are heat-fused, spherical-shaped, elliptical-shaped, plate-shaped, rod-shaped, or irregular-shaped. When an inorganic filler having the above-mentioned shape is used, if the coating shear rate is increased, a high shearing force is applied to the inorganic filler, so that the anisotropy tends to increase. On the other hand, when the coating shear rate is reduced, the shearing force is not applied to the inorganic filler, so that the inorganic filler tends to be oriented isotropically.
　一方、前記無機フィラーが繊維径の長いワラストナイトのような長繊維径無機フィラーである場合には、前記塗工せん断速度を大きくすると、長繊維どうしが絡み合う、あるいはドクターブレードの刃に長繊維がひっかかるためばらばらの配向になり、異方性が低くなる傾向がある。一方、前記塗工せん断速度を小さくすると、長繊維が、互いに絡み合うことがなく、ドクターブレードの刃にひっかからないので、配向しやすくなり、異方性は高くなる傾向がある。 On the other hand, when the inorganic filler is a long fiber diameter inorganic filler such as long wollastonite having a large fiber diameter, when the coating shear rate is increased, the long fibers are entangled with each other, or the long blades of the doctor blade are long fibers. Tend to be in a disoriented orientation due to the trapping of the, and anisotropy tends to be low. On the other hand, when the coating shear rate is reduced, the long fibers do not become entangled with each other and do not get caught by the blade of the doctor blade, so that they tend to be oriented and the anisotropy tends to increase.
　＜非水電解液二次電池用セパレータ＞
　本発明の一実施形態に係る非水電解液二次電池用セパレータは、ポリオレフィン多孔質フィルムを含む。 <Nonaqueous electrolyte secondary battery separator>
A separator for a non-aqueous electrolyte secondary battery according to an embodiment of the present invention includes a polyolefin porous film.
　また、本発明の一実施形態に係る非水電解液二次電池用セパレータは、ポリオレフィン多孔質フィルムの他に、接着層、耐熱層、保護層等のその他の層をさらに備えていてもよい。 The separator for a non-aqueous electrolyte secondary battery according to one embodiment of the present invention may further include other layers such as an adhesive layer, a heat resistant layer, and a protective layer, in addition to the polyolefin porous film.
　＜ポリオレフィン多孔質フィルム＞
　本発明の一実施形態における非水電解液二次電池は、ポリオレフィン多孔質フィルムを備えていてもよい。以下では、ポリオレフィン多孔質フィルムを単に「多孔質フィルム」と称することがある。前記多孔質フィルムは、ポリオレフィン系樹脂を主成分とし、その内部に連結した細孔を多数有しており、一方の面から他方の面に気体および液体を通過させることが可能となっている。前記多孔質フィルムは、単独で非水電解液二次電池用セパレータとなり得る。また、上述の多孔質層が積層された非水電解液二次電池用積層セパレータにおける多孔質基材ともなり得る。 <Polyolefin porous film>
The non-aqueous electrolyte secondary battery in one embodiment of the present invention may include a polyolefin porous film. Below, a polyolefin porous film may only be called a "porous film." The porous film contains a polyolefin-based resin as a main component and has a large number of pores connected to the inside thereof, so that a gas and a liquid can pass from one surface to the other surface. The porous film alone can serve as a separator for a non-aqueous electrolyte secondary battery. It can also serve as a porous base material in the laminated separator for a non-aqueous electrolyte secondary battery in which the above-mentioned porous layer is laminated.
　前記ポリオレフィン多孔質フィルムの少なくとも一方の面上に、前記多孔質層が積層されてなる積層体を、本明細書において、「非水電解液二次電池用積層セパレータ」または「積層セパレータ」とも称する。 On at least one surface of the polyolefin porous film, a laminate in which the porous layer is laminated, in the present specification, also referred to as "non-aqueous electrolyte secondary battery laminated separator" or "laminated separator" ..
　多孔質フィルムに占めるポリオレフィンの割合は、多孔質フィルム全体の５０体積％以上であり、９０体積％以上であることがより好ましく、９５体積％以上であることがさらに好ましい。また、前記ポリオレフィンには、重量平均分子量が５×１０５～１５×１０６の高分子量成分が含まれていることがより好ましい。特に、ポリオレフィンに重量平均分子量が１００万以上の高分子量成分が含まれていると、非水電解液二次電池用セパレータの強度が向上するのでより好ましい。 The proportion of polyolefin in the porous film is 50% by volume or more of the entire porous film, more preferably 90% by volume or more, and further preferably 95% by volume or more. Further, it is more preferable that the polyolefin contains a high molecular weight component having a weight average molecular weight of 5 × 10 5 to 15 × 10 6 . In particular, when the polyolefin contains a high molecular weight component having a weight average molecular weight of 1,000,000 or more, the strength of the separator for a non-aqueous electrolyte secondary battery is improved, which is more preferable.
　熱可塑性樹脂である前記ポリオレフィンとしては、具体的には、例えば、エチレン、プロピレン、１－ブテン、４－メチル－１－ペンテンおよび１－ヘキセン等の単量体を重合してなる、単独重合体または共重合体が挙げられる。前記単独重合体としては、例えばポリエチレン、ポリプロピレン、ポリブテンを挙げることができる。また、前記共重合体としては、例えばエチレン－プロピレン共重合体を挙げることができる。 The polyolefin, which is a thermoplastic resin, is specifically a homopolymer obtained by polymerizing monomers such as ethylene, propylene, 1-butene, 4-methyl-1-pentene and 1-hexene. Alternatively, a copolymer may be used. Examples of the homopolymer include polyethylene, polypropylene and polybutene. Examples of the copolymer include ethylene-propylene copolymer.
　このうち、過大電流が流れることをより低温で阻止することができるため、ポリエチレンがより好ましい。なお、この過大電流が流れることを阻止することをシャットダウンともいう。前記ポリエチレンとしては、低密度ポリエチレン、高密度ポリエチレン、線状ポリエチレン（エチレン－α－オレフィン共重合体）、重量平均分子量が１００万以上の超高分子量ポリエチレン等が挙げられる。このうち、重量平均分子量が１００万以上の超高分子量ポリエチレンがさらに好ましい。 Among these, polyethylene is more preferable because it can block excessive current from flowing at lower temperatures. Note that blocking the flow of this excessive current is also referred to as shutdown. Examples of the polyethylene include low density polyethylene, high density polyethylene, linear polyethylene (ethylene-α-olefin copolymer), and ultrahigh molecular weight polyethylene having a weight average molecular weight of 1,000,000 or more. Among these, ultrahigh molecular weight polyethylene having a weight average molecular weight of 1,000,000 or more is more preferable.
　多孔質フィルムの膜厚は、４～４０μｍであることが好ましく、５～３０μｍであることがより好ましく、６～１５μｍであることがさらに好ましい。 The thickness of the porous film is preferably 4 to 40 μm, more preferably 5 to 30 μm, and further preferably 6 to 15 μm.
　多孔質フィルムの単位面積当たりの目付は、強度、膜厚、重量およびハンドリング性を考慮して適宜決定することができる。ただし、非水電解液二次電池の重量エネルギー密度および体積エネルギー密度を高くすることができるように、前記目付は、４～２０ｇ／ｍ２であることが好ましく、４～１２ｇ／ｍ２であることがより好ましく、５～１０ｇ／ｍ２であることがさらに好ましい。 The basis weight per unit area of the porous film can be appropriately determined in consideration of strength, film thickness, weight and handleability. However, the basis weight is preferably 4 to 20 g / m 2 , and preferably 4 to 12 g / m 2 so that the weight energy density and the volume energy density of the non-aqueous electrolyte secondary battery can be increased. More preferably, it is more preferably 5 to 10 g / m 2 .
　多孔質フィルムの透気度は、ガーレ値で３０～５００ｓｅｃ／１００ｍＬであることが好ましく、５０～３００ｓｅｃ／１００ｍＬであることがより好ましい。多孔質フィルムが前記透気度を有することにより、充分なイオン透過性を得ることができる。多孔質フィルムに上述の多孔質層を積層させた非水電解液二次電池用積層セパレータの透気度は、ガーレ値で３０～１０００ｓｅｃ／１００ｍＬであることが好ましく、５０～８００ｓｅｃ／１００ｍＬであることがより好ましい。非水電解液二次電池用積層セパレータは、前記透気度を有することにより、非水電解液二次電池において、充分なイオン透過性を得ることができる。 The air permeability of the porous film is preferably 30 to 500 sec / 100 mL in Gurley value, and more preferably 50 to 300 sec / 100 mL. When the porous film has the above-mentioned air permeability, sufficient ion permeability can be obtained. The air permeability of the laminated separator for a non-aqueous electrolyte secondary battery in which the above-mentioned porous layer is laminated on the porous film is preferably 30 to 1000 sec / 100 mL in terms of Gurley value, and is 50 to 800 sec / 100 mL. Is more preferable. Since the laminated separator for a non-aqueous electrolyte secondary battery has the above-mentioned air permeability, it is possible to obtain sufficient ion permeability in the non-aqueous electrolyte secondary battery.
　多孔質フィルムの空隙率は、電解液の保持量を高めると共に、過大電流が流れることをより低温で確実に阻止する機能を得ることができるように、２０～８０体積％であることが好ましく、３０～７５体積％であることがより好ましい。また、多孔質フィルムが有する細孔の孔径は、充分なイオン透過性を得ることができ、かつ、正極板および負極板への粒子の入り込みを防止することができるように、０．３μｍ以下であることが好ましく、０．１４μｍ以下であることがより好ましい。 The porosity of the porous film is preferably 20 to 80% by volume so as to increase the holding amount of the electrolytic solution and to surely prevent the flow of an excessive current at a lower temperature. It is more preferably 30 to 75% by volume. The pore size of the pores of the porous film is 0.3 μm or less so that sufficient ion permeability can be obtained and particles can be prevented from entering the positive electrode plate and the negative electrode plate. Is preferably 0.14 μm or less, and more preferably 0.14 μm or less.
　＜ポリオレフィン多孔質フィルムの製造方法＞
　前記ポリオレフィン多孔質フィルムの製造方法は特に限定されるものではない。例えば、ポリオレフィン系樹脂と、無機充填剤および可塑剤等の孔形成剤と、任意で酸化防止剤等を混練した後に押し出すことで、シート状のポリオレフィン樹脂組成物を作製する。適当な溶媒にて当該孔形成剤を当該シート状のポリオレフィン樹脂組成物から除去した後、当該孔形成剤が除去されたポリオレフィン樹脂組成物を延伸することで、ポリオレフィン多孔質フィルムを製造することができる。 <Method for producing polyolefin porous film>
The method for producing the polyolefin porous film is not particularly limited. For example, a sheet-shaped polyolefin resin composition is prepared by kneading a polyolefin resin, a pore-forming agent such as an inorganic filler and a plasticizer, and optionally an antioxidant and the like and then extruding the kneaded product. After removing the pore-forming agent from the sheet-shaped polyolefin resin composition with an appropriate solvent, the polyolefin resin composition from which the pore-forming agent has been removed may be stretched to produce a polyolefin porous film. it can.
　上記無機充填剤としては、特に限定されるものではなく、無機フィラー、具体的には炭酸カルシウム等が挙げられる。上記可塑剤としては、特に限定されるものではなく、流動パラフィン等の低分子量の炭化水素が挙げられる。 The above-mentioned inorganic filler is not particularly limited, and examples thereof include inorganic fillers, specifically calcium carbonate and the like. The plasticizer is not particularly limited, and examples thereof include low molecular weight hydrocarbons such as liquid paraffin.
　具体的には、以下に示すような工程を含む方法を挙げることができる。
（Ａ）超高分子量ポリエチレンと、重量平均分子量１万以下の低分子量ポリエチレンと、炭酸カルシウムまたは可塑剤等の孔形成剤と、酸化防止剤とを混練してポリオレフィン樹脂組成物を得る工程、
（Ｂ）得られたポリオレフィン樹脂組成物を一対の圧延ローラで圧延し、速度比を変えた巻き取りローラで引っ張りながら段階的に冷却し、シートを成形する工程、
（Ｃ）得られたシートの中から適当な溶媒にて孔形成剤を除去する工程、
（Ｄ）孔形成剤が除去されたシートを適当な延伸倍率にて延伸する工程。 Specifically, a method including the following steps can be mentioned.
(A) a step of kneading an ultrahigh molecular weight polyethylene, a low molecular weight polyethylene having a weight average molecular weight of 10,000 or less, a pore forming agent such as calcium carbonate or a plasticizer, and an antioxidant to obtain a polyolefin resin composition,
(B) a step of rolling the obtained polyolefin resin composition with a pair of rolling rollers and gradually cooling it while pulling it with a take-up roller having a different speed ratio to form a sheet,
(C) a step of removing the pore forming agent from the obtained sheet with a suitable solvent,
(D) A step of stretching the sheet from which the pore forming agent has been removed at an appropriate stretching ratio.
　＜非水電解液二次電池用積層セパレータの製造方法＞
　本発明の一実施形態における非水電解液二次電池用積層セパレータの製造方法としては、例えば、上述の「多孔質層の製造方法」において、前記塗工液を塗布する基材として、上述のポリオレフィン多孔質フィルムを使用する方法を挙げることができる。 <Method of manufacturing laminated separator for non-aqueous electrolyte secondary battery>
Examples of the method for producing a laminated separator for a non-aqueous electrolyte secondary battery in one embodiment of the present invention include, for example, in the above-mentioned “method for producing a porous layer”, as the base material to which the coating liquid is applied, The method of using a polyolefin porous film can be mentioned.
　＜非水電解液＞
　本発明の一実施形態に係る非水電解液二次電池に含まれ得る非水電解液は、一般に非水電解液二次電池に使用される非水電解液であれば特に限定されない。前記非水電解液としては、例えば、リチウム塩を有機溶媒に溶解してなる非水電解液を用いることができる。リチウム塩としては、例えば、ＬｉＣｌＯ４、ＬｉＰＦ６、ＬｉＡｓＦ６、ＬｉＳｂＦ６、ＬｉＢＦ４、ＬｉＣＦ３ＳＯ３、ＬｉＮ（ＣＦ３ＳＯ２）２、ＬｉＣ（ＣＦ３ＳＯ２）３、Ｌｉ２Ｂ１０Ｃｌ１０、低級脂肪族カルボン酸リチウム塩およびＬｉＡｌＣｌ４等が挙げられる。前記リチウム塩は、１種類のみを用いてもよく、２種類以上を組み合わせて用いてもよい。 <Non-aqueous electrolyte>
The non-aqueous electrolyte that can be included in the non-aqueous electrolyte secondary battery according to the embodiment of the present invention is not particularly limited as long as it is a non-aqueous electrolyte that is generally used in non-aqueous electrolyte secondary batteries. As the non-aqueous electrolyte, for example, a non-aqueous electrolyte obtained by dissolving a lithium salt in an organic solvent can be used. Examples of the lithium salt include LiClO 4 , LiPF 6 , LiAsF 6 , LiSbF 6 , LiBF 4 , LiCF 3 SO 3 , LiN (CF 3 SO 2 ) 2 , LiC (CF 3 SO 2 ) 3 , Li 2 B 10 Cl. 10 , lower aliphatic carboxylic acid lithium salt, LiAlCl 4 and the like. The lithium salt may be used alone or in combination of two or more kinds.
　非水電解液を構成する有機溶媒としては、例えば、カーボネート類、エーテル類、エステル類、ニトリル類、アミド類、カーバメート類および含硫黄化合物、ならびにこれらの有機溶媒にフッ素基が導入されてなる含フッ素有機溶媒等が挙げられる。前記有機溶媒は、１種類のみを用いてもよく、２種類以上を組み合わせて用いてもよい。 Examples of the organic solvent that constitutes the non-aqueous electrolytic solution include carbonates, ethers, esters, nitriles, amides, carbamates and sulfur-containing compounds, and fluorine-containing compounds introduced into these organic solvents. Fluorine organic solvents and the like can be mentioned. The organic solvent may be used alone or in combination of two or more.
　＜非水電解液二次電池の製造方法＞
　本発明の一実施形態に係る非水電解液二次電池を製造する方法として、例えば、以下の方法が挙げられる。まず、前記正極板、多孔質層、非水電解液二次電池用セパレータ、および負極板をこの順で配置して非水電解液二次電池用部材を形成する。その後、非水電解液二次電池の筐体となる容器に当該非水電解液二次電池用部材を入れ、次いで、当該容器内を非水電解液で満たした後、減圧しつつ密閉する。これにより、本発明の一実施形態に係る非水電解液二次電池を製造することができる。 <Method for manufacturing non-aqueous electrolyte secondary battery>
Examples of the method for producing the non-aqueous electrolyte secondary battery according to the embodiment of the present invention include the following methods. First, the positive electrode plate, the porous layer, the non-aqueous electrolyte secondary battery separator, and the negative electrode plate are arranged in this order to form a non-aqueous electrolyte secondary battery member. After that, the member for a non-aqueous electrolyte secondary battery is put in a container that will be the casing of the non-aqueous electrolyte secondary battery, and then the inside of the container is filled with the non-aqueous electrolyte solution and then sealed while depressurizing. Thereby, the non-aqueous electrolyte secondary battery according to the embodiment of the present invention can be manufactured.
　本発明の一実施形態に係る非水電解液二次電池は、上述したように、ポリオレフィン多孔質フィルムを含む非水電解液二次電池用セパレータと、多孔質層と、正極板と、負極板と、を備えている。特に、本発明の一実施形態に係る非水電解液二次電池は、以下の（ｉ）～（ｉｉｉ）の要件を充足する。
（ｉ）多孔質層は、下記式（１）で表される値が、０．１０～０．４２の範囲にある。
｜１－Ｔ／Ｍ｜・・・（１）
（式（１）中、Ｔは、ＴＤにおける０．１Ｎの一定荷重下でのスクラッチ試験における、臨界荷重までの距離を表し、Ｍは、ＭＤにおける０．１Ｎの一定荷重下でのスクラッチ試験における、臨界荷重までの距離を表す。）
（ｉｉ）正極板の、電極活物質層が剥がれるまでの折り曲げ回数が１３０回以上である。（ｉｉｉ）負極板の、電極活物質層が剥がれるまでの折り曲げ回数が１６５０回以上である。 The non-aqueous electrolyte secondary battery according to one embodiment of the present invention is, as described above, a separator for a non-aqueous electrolyte secondary battery including a polyolefin porous film, a porous layer, a positive electrode plate, and a negative electrode plate. And are equipped with. In particular, the non-aqueous electrolyte secondary battery according to the embodiment of the present invention satisfies the following requirements (i) to (iii).
(I) The porous layer has a value represented by the following formula (1) in the range of 0.10 to 0.42.
| 1-T / M | ... (1)
(In Formula (1), T represents a distance to a critical load in a scratch test under a constant load of 0.1 N in TD, and M represents a scratch test under a constant load of 0.1 N in MD. , Represents the distance to the critical load.)
(Ii) The number of times the positive electrode plate is bent until the electrode active material layer is peeled off is 130 times or more. (Iii) The number of times the negative electrode plate is bent until the electrode active material layer is peeled off is 1,650 times or more.
　（ｉ）の要件によって、本発明の一実施形態に係る非水電解液二次電池では、多孔質層が均一かつ緻密な構造をとることにより、多孔質層内でリチウムイオンの分布が均一に保持される。そして、（ｉｉ）および（ｉｉｉ）の要件によって、電極全体が活物質の膨張および収縮に等方的に追従しやすい。従って、電極活物質層内部に含まれる成分同士の密着性、および、電極活物質層と集電体との密着性が維持されやすい。 Due to the requirement of (i), in the non-aqueous electrolyte secondary battery according to the embodiment of the present invention, the porous layer has a uniform and dense structure, so that the distribution of lithium ions in the porous layer is uniform. Retained. Then, due to the requirements (ii) and (iii), the entire electrode easily isotropically follows the expansion and contraction of the active material. Therefore, the adhesiveness between the components contained in the electrode active material layer and the adhesiveness between the electrode active material layer and the current collector are easily maintained.
　したがって、前記（ｉ）～（ｉｉｉ）の要件を充足する非水電解液二次電池では、（ａ）多孔質層内でのリチウムイオンの分布が均一であるため、リチウムイオンの透過性が良好であり、かつ、（ｂ）上述の密着性が維持されやすいため、充放電サイクルの過程での非水電解液二次電池の劣化が抑制される。それゆえ、充放電サイクル後（例えば、１００サイクル経過）であっても、電池の放電容量回復特性が向上すると考えられる。 Therefore, in the non-aqueous electrolyte secondary battery satisfying the above requirements (i) to (iii), (a) the lithium ion distribution is uniform in the porous layer, and thus the lithium ion permeability is good. And (b) since the above-mentioned adhesion is easily maintained, deterioration of the non-aqueous electrolyte secondary battery in the course of the charge / discharge cycle is suppressed. Therefore, it is considered that the discharge capacity recovery characteristic of the battery is improved even after the charge / discharge cycle (for example, 100 cycles have elapsed).
　本発明は上述した各実施形態に限定されるものではなく、請求項に示した範囲で種々の変更が可能であり、異なる実施形態にそれぞれ開示された技術的手段を適宜組み合わせて得られる実施形態についても本発明の技術的範囲に含まれる。 The present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the claims, and the embodiments obtained by appropriately combining the technical means disclosed in the different embodiments. Is also included in the technical scope of the present invention.
　以下、実施例および比較例により、本発明をさらに詳細に説明するが、本発明はこれら実施例に限定されるものではない。 Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples.
　［測定方法］
　実施例および比較例における各測定を以下の方法で行った。 [Measuring method]
Each measurement in Examples and Comparative Examples was performed by the following methods.
　（１．耐折試験）
　以下の実施例および比較例において得られた正極板または負極板から、長さ１０５ｍｍ×幅１５ｍｍの試験片を切り出した。この試験片を用いてＭＩＴ試験機法に準じ、耐折試験を行った。 (1. Fold endurance test)
Test pieces each having a length of 105 mm and a width of 15 mm were cut out from the positive electrode plate or the negative electrode plate obtained in the following Examples and Comparative Examples. Using this test piece, a folding endurance test was performed according to the MIT tester method.
　耐折試験はＭＩＴ型耐折試験機（安田精機製）を用い、ＪＩＳ　Ｐ　８１１５（１９９４）に規定されたＭＩＴ試験機法に準じて、荷重：１Ｎ、折り曲げ部Ｒ：０．３８ｍｍ、折り曲げ速度１７５往復／分とし、試験片の一端を固定し左右へ４５度の角度に折り曲げることによって行った。 For the folding endurance test, a MIT type folding endurance tester (manufactured by Yasuda Seiki) was used, and in accordance with the MIT tester method specified in JIS P 8115 (1994), load: 1N, bent portion R: 0.38mm, bending speed 175 reciprocations / minute, one end of the test piece was fixed, and the test piece was bent left and right at an angle of 45 degrees.
　これにより、正極板または負極板から電極活物質層が剥がれるまでの折り曲げ回数を測定した。ここでの折り曲げ回数は、上記ＭＩＴ型耐折試験機のカウンターに表示される往復折り曲げ回数のことである。 With this, the number of times of bending until the electrode active material layer was peeled from the positive electrode plate or the negative electrode plate was measured. The number of times of bending here is the number of times of reciprocal bending displayed on the counter of the MIT folding endurance tester.
　（２．スクラッチ試験）
　臨界荷重値、および臨界荷重までの距離のＴ／Ｍ比を以下に示すスクラッチ試験にて測定した。以下に記載する以外の測定条件等は、ＪＩＳ　Ｒ　３２５５と同様の条件等にして、測定を行った。また、測定装置は、マイクロスクラッチ試験装置（ＣＳＥＭ　Ｉｎｓｔｒｕｍｅｎｔｓ社製）を使用した。
（１）実施例、比較例にて製造された多孔質層を多孔質基材に積層することにより得た積層体を２０ｍｍ×６０ｍｍに裁断した。その後、当該裁断した積層体のセパレータ側、すなわち多孔質基材側の全面に、水で５倍希釈したアラビックヤマト水性液状糊（ヤマト株式会社製）を目付１．５ｇ／ｍ２程度に少量で薄く塗布した。次いで、その水性液状糊を塗布した面を、３０ｍｍ×７０ｍｍのガラス製プレパラート上に貼合した後、２５℃の温度下にて一昼夜乾燥させることにより、試験用サンプルを作製した。なお、上記貼合のときは、積層体とガラス製プレパラートとの間に気泡が入らない様にした。
（２）工程（１）にて作製された試験用サンプルを、マイクロスクラッチ試験装置（ＣＳＥＭ　Ｉｎｓｔｒｕｍｅｎｔｓ社製）に設置した。当該試験装置におけるダイヤモンド圧子（頂角１２０゜、先端半径０．２ｍｍの円錐状）によって当該試験用サンプル上に０．１Ｎの大きさの垂直荷重をかけたままの状態にて、当該試験装置におけるテーブルを、積層体のＴＤに向けて５ｍｍ／ｍｉｎの速さにて、１０ｍｍの距離を移動させた。その間の、上記ダイヤモンド圧子と当該試験用サンプルとの間に発生する応力、すなわち摩擦力を測定した。
（３）工程（２）にて測定された応力の変位と、上記テーブルの移動距離との関係を示す曲線グラフを作成した。当該曲線グラフから、ＴＤにおける、臨界荷重値および、臨界荷重に至るまでの距離を算出した。
（４）上記テーブルの移動方向をＭＤに変更して、上述の工程（１）～（３）を繰り返して行い、ＭＤにおける、臨界荷重値および、臨界荷重に至るまでの距離を算出した。 (2. Scratch test)
The critical load value and the T / M ratio of the distance to the critical load were measured by the scratch test shown below. The measurement conditions were the same as those of JIS R 3255 except for those described below. A micro scratch tester (manufactured by CSEM Instruments) was used as the measuring device.
(1) A laminate obtained by laminating the porous layers produced in Examples and Comparative Examples on a porous substrate was cut into 20 mm × 60 mm. Then, an arabic Yamato aqueous liquid paste (manufactured by Yamato Co., Ltd.) diluted 5 times with water was applied on the separator side of the cut laminate, that is, the entire surface of the porous substrate side, in a small amount of about 1.5 g / m 2 per unit area. It was applied thinly. Next, the surface coated with the aqueous liquid paste was pasted on a glass slide having a size of 30 mm × 70 mm and then dried at 25 ° C. for 24 hours to prepare a test sample. At the time of the above-mentioned bonding, bubbles were prevented from entering between the laminate and the glass slide.
(2) The test sample prepared in step (1) was placed in a micro scratch tester (manufactured by CSEM Instruments). With the diamond indenter (conical shape having an apex angle of 120 ° and a tip radius of 0.2 mm) in the test apparatus, a vertical load of 0.1 N was applied to the test sample in the test apparatus. The table was moved toward the TD of the laminate at a speed of 5 mm / min and a distance of 10 mm. During that time, the stress generated between the diamond indenter and the test sample, that is, the frictional force was measured.
(3) A curve graph showing the relationship between the displacement of the stress measured in the step (2) and the moving distance of the table was created. From the curve graph, the critical load value in TD and the distance to reach the critical load were calculated.
(4) The moving direction of the table was changed to MD, and the above steps (1) to (3) were repeated to calculate the critical load value and the distance to reach the critical load in MD.
　（３．膜厚（単位：μｍ））
　多孔質層、多孔質基材、正極活物質層および負極活物質層の厚さは、株式会社ミツトヨ製の高精度デジタル測長機（ＶＬ－５０）を用いて測定した。なお、正極活物質層の厚さは、正極板の厚さから集電体であるアルミニウム箔の厚さを差し引くことで算出し、また、負極活物質層の厚さは、負極板の厚さから集電体である銅箔の厚さを差し引くことで算出した。また、多孔質層の厚さは、各々の積層体の塗工部の厚さから、未塗工部の厚さを差し引くことで算出した。なお、塗工部とは多孔質層が形成されている部分を指し、未塗工部とは多孔質層が形成されていない部分を指す。 (3. Film thickness (unit: μm))
The thicknesses of the porous layer, the porous substrate, the positive electrode active material layer and the negative electrode active material layer were measured using a high precision digital length measuring machine (VL-50) manufactured by Mitutoyo Corporation. The thickness of the positive electrode active material layer is calculated by subtracting the thickness of the aluminum foil that is the current collector from the thickness of the positive electrode plate, and the thickness of the negative electrode active material layer is the thickness of the negative electrode plate. It was calculated by subtracting the thickness of the copper foil, which is the current collector, from. Further, the thickness of the porous layer was calculated by subtracting the thickness of the uncoated portion from the thickness of the coated portion of each laminate. The coated portion refers to the portion where the porous layer is formed, and the uncoated portion refers to the portion where the porous layer is not formed.
　（４．粒度分布）
　フィラーの体積基準の粒度分布は、島津製作所製　レーザー回折式粒度分布計ＳＡＬＤ２２００を用いて、Ｄ１０、Ｄ５０、Ｄ９０を測定することにより算出した。ここで、体積基準による積算分布が５０％になる値の粒子径、１０％になる値の粒子径、９０％になる値の粒子径を、それぞれＤ５０、Ｄ１０、Ｄ９０と呼ぶ。また、Ｄ５０は、中心粒径とも呼ぶ。 (4. Particle size distribution)
The volume-based particle size distribution of the filler was calculated by measuring D10, D50, and D90 using a laser diffraction particle size distribution analyzer SALD2200 manufactured by Shimadzu Corporation. Here, the particle diameter at which the cumulative distribution based on volume is 50%, the particle diameter at 10%, and the particle diameter at 90% are called D50, D10, and D90, respectively. D50 is also referred to as the median particle size.
　（５．比表面積）
　フィラーの比表面積は、ＢＥＬＳＯＲＰ－ｍｉｎｉ（マイクロトラック・ベル株式会社製）を用いて測定した。前処理温度８０℃で８時間真空乾燥を行ったフィラーを、定容法を用いて、窒素による吸着脱離等温線を測定し、ＢＥＴ法にて算出した。定容法における各種条件は、以下のとおりである：吸着温度；７７Ｋ、吸着質；窒素、飽和蒸気圧；実測値、吸着質断面積；０．１６２ｎｍ２、平衡待ち時間（吸着平衡状態（吸脱着の際の圧力変化が所定の値以下になる状態）に達してからの待ち時間）；５００ｓｅｃ。また、細孔容積は、ＭＰ法、ＢＪＨ法により算出し、前処理装置は、ＢＥＬＰＲＥＰ－ｖａｃＩＩ（マイクロトラック・ベル株式会社製）を用いた。 (5. Specific surface area)
The specific surface area of the filler was measured using BELSORP-mini (manufactured by Microtrac Bell Co., Ltd.). The adsorption-desorption isotherm by nitrogen of the filler that had been vacuum dried at a pretreatment temperature of 80 ° C. for 8 hours was measured by the constant volume method, and calculated by the BET method. Various conditions in the constant volume method are as follows: adsorption temperature; 77 K, adsorbate; nitrogen, saturated vapor pressure; measured value, adsorbate cross section; 0.162 nm 2 , equilibrium waiting time (adsorption equilibrium state (adsorption Waiting time after the pressure change during desorption reaches a value below a predetermined value)): 500 sec. The pore volume was calculated by the MP method and the BJH method, and the pretreatment device used was BELPREP-vacII (manufactured by Microtrac Bell Co., Ltd.).
　（６．１００サイクルの充放電後の放電回復容量の測定）
　＜６－１．初期充放電＞
　実施例および比較例にて製造された、充放電サイクルを経ていない新たな非水電解液二次電池に対して、電圧範囲：２．７～４．１Ｖ、充電電流値：０．２ＣのＣＣ－ＣＶ充電（終止電流条件０．０２Ｃ）、放電電流値：０．２ＣのＣＣ放電を１サイクルとして、４サイクルの初期充放電を２５℃にて実施した。ここで、１Ｃとは、１時間率の放電容量による定格容量を１時間で放電する電流値である。また、ＣＣ－ＣＶ充電とは、設定した一定の電流で充電し、所定の電圧に到達後、電流を絞りながら、その電圧を維持する充電方法である。さらに、ＣＣ放電とは設定した一定の電流で所定の電圧まで放電する方法である。これらの用語の意味は、本明細書において同様である。 (6. Measurement of discharge recovery capacity after 100 cycles of charge / discharge)
<6-1. Initial charge / discharge>
For the new non-aqueous electrolyte secondary batteries manufactured in Examples and Comparative Examples and not undergoing charge / discharge cycles, CC of voltage range: 2.7 to 4.1V, charging current value: 0.2C -CV charge (end current condition 0.02C), discharge current value: CC discharge of 0.2C was set as one cycle, and initial charge and discharge for four cycles were performed at 25 ° C. Here, 1C is a current value for discharging the rated capacity by the discharge capacity of 1 hour rate in 1 hour. CC-CV charging is a charging method in which charging is performed with a set constant current, and after reaching a predetermined voltage, the current is reduced while maintaining the voltage. Furthermore, CC discharge is a method of discharging to a predetermined voltage with a set constant current. The meanings of these terms are the same in this specification.
　＜６－２．サイクル試験＞
　初期充放電後の非水電解液二次電池を、電圧範囲：２．７～４．２Ｖ、充電電流値：１ＣのＣＣ－ＣＶ充電（終止電流条件０．０２Ｃ）、放電電流値：１０ＣのＣＣ放電を１サイクルとして、１００サイクルの充放電を５５℃にて実施した。 <6-2. Cycle test>
After the initial charge / discharge, the non-aqueous electrolyte secondary battery was charged at CC-CV with a voltage range of 2.7 to 4.2 V and a charging current value of 1 C (end current condition of 0.02 C) and a discharge current value of 10 C. 100 cycles of charge and discharge were carried out at 55 ° C. with CC discharge as one cycle.
　＜６－３．１００サイクルの充放電後の放電回復容量試験＞
　１００サイクルの充放電を行った非水電解液二次電池に対して、電圧範囲：２．７Ｖ～４．２Ｖ、充電電流値：１ＣのＣＣ－ＣＶ充電（終止電流条件０．０２Ｃ）、放電電流値：０．２ＣのＣＣ放電を１サイクルとして３サイクルの充放電を５５℃にて実施した。その３サイクル目の放電容量を、放電回復容量とした。後述する表１では、当該放電回復容量を「１００サイクル後の放電回復容量」として示す。 <6-3. Discharge recovery capacity test after 100 cycles of charge / discharge>
CC-CV charging with a voltage range of 2.7V to 4.2V and a charging current value of 1C (discharging current condition 0.02C) for a non-aqueous electrolyte secondary battery that has been charged and discharged for 100 cycles. A current value: CC discharge of 0.2 C was set as one cycle, and three cycles of charging and discharging were performed at 55 ° C. The discharge capacity at the third cycle was defined as the discharge recovery capacity. In Table 1 described later, the discharge recovery capacity is shown as “discharge recovery capacity after 100 cycles”.
　上記の放電回復容量試験は、１００サイクルの充放電サイクル後に低いレート（０．２Ｃ）で放電を実施し、より正確に放電容量を確認する試験方法であり、電池全体の放電性能の劣化度、特に電極の放電性能の劣化度を確認することができる。 The above-mentioned discharge recovery capacity test is a test method in which discharge is carried out at a low rate (0.2 C) after 100 charge / discharge cycles and the discharge capacity is confirmed more accurately. In particular, the degree of deterioration of the discharge performance of the electrode can be confirmed.
　［実施例１］
　〔多孔質層、積層体の作製〕
　（多孔質基材（Ａ層））
　ポリオレフィンであるポリエチレンを用いて多孔質基材を作製した。 [Example 1]
[Preparation of porous layer and laminate]
(Porous substrate (A layer))
A porous substrate was produced using polyethylene, which is a polyolefin.
　即ち、超高分子量ポリエチレン粉末（３４０Ｍ、三井化学株式会社製）７０重量部と、重量平均分子量１０００のポリエチレンワックス（ＦＮＰ－０１１５、日本精鑞株式会社製）３０重量部とを混合して混合ポリエチレンを得た。得られた混合ポリエチレン１００重量部に対して、酸化防止剤（Ｉｒｇ１０１０、チバ・スペシャリティ・ケミカルズ株式会社製）０．４重量部、酸化防止剤（Ｐ１６８、チバ・スペシャリティ・ケミカルズ株式会社製）０．１重量部、およびステアリン酸ナトリウム１．３重量部を加え、さらに、全体積に占める割合が３８体積％となるように、平均粒子径０．１μｍの炭酸カルシウム（丸尾カルシウム株式会社製）を加えた。この組成物を粉末のまま、ヘンシェルミキサーで混合した後、二軸混練機で溶融混練することにより、ポリエチレン樹脂組成物を得た。次いで、このポリエチレン樹脂組成物を、表面温度が１５０℃に設定された一対のロールにて圧延することにより、シートを作製した。このシートを、４ｍｏｌ／Ｌの塩酸に０．５重量％の非イオン系界面活性剤を配合して調製した塩酸水溶液に浸漬させることで炭酸カルシウムを溶解して除去した。続いて、当該シートを１０５℃で６倍に延伸することにより、ポリエチレン製の多孔質基材（Ａ層）を作製した。多孔質基材の空隙率５３％、目付７ｇ／ｍ２、厚さ１６μｍであった。 That is, 70 parts by weight of ultra-high molecular weight polyethylene powder (340M, manufactured by Mitsui Chemicals, Inc.) and 30 parts by weight of polyethylene wax having a weight average molecular weight of 1000 (FNP-0115, manufactured by Nippon Seiro Co., Ltd.) are mixed and mixed polyethylene. Got With respect to 100 parts by weight of the obtained mixed polyethylene, 0.4 parts by weight of an antioxidant (Irg1010, manufactured by Ciba Specialty Chemicals Co., Ltd.), and an antioxidant (P168, manufactured by Ciba Specialty Chemicals Co., Ltd.) 0. 1 part by weight and 1.3 parts by weight of sodium stearate were added, and further, calcium carbonate having an average particle size of 0.1 μm (manufactured by Maruo Calcium Co., Ltd.) was added so that the ratio of the total volume was 38% by volume. It was This composition as a powder was mixed with a Henschel mixer and then melt-kneaded with a biaxial kneader to obtain a polyethylene resin composition. Then, this polyethylene resin composition was rolled with a pair of rolls whose surface temperature was set to 150 ° C. to prepare a sheet. This sheet was immersed in an aqueous hydrochloric acid solution prepared by mixing 0.5 mol% of a nonionic surfactant in 4 mol / L hydrochloric acid to dissolve and remove calcium carbonate. Then, the said sheet | seat was drawn 6 times at 105 degreeC, and the porous base material (A layer) made from polyethylene was produced. The porosity of the porous substrate was 53%, the basis weight was 7 g / m 2 , and the thickness was 16 μm.
　（多孔質層（Ｂ層））
　（塗工液の製造）
　無機フィラー１として、酸素原子質量百分率が２０％である六角板状酸化亜鉛（堺化学工業株式会社製、商品名：ＸＺ－１００Ｆ）を用いた。無機フィラー１のＤ５０、Ｄ１０、Ｄ９０は、それぞれ０．４μｍ、０．２μｍ、２．１μｍであった。また、無機フィラー１の単位面積当たりのＢＥＴ比表面積は、７．３ｍ２／ｇであった。 (Porous layer (B layer))
(Production of coating liquid)
As the inorganic filler 1, hexagonal plate-shaped zinc oxide having a mass percentage of oxygen atoms of 20% (manufactured by Sakai Chemical Industry Co., Ltd., trade name: XZ-100F) was used. D50, D10, and D90 of the inorganic filler 1 were 0.4 μm, 0.2 μm, and 2.1 μm, respectively. The BET specific surface area per unit area of the inorganic filler 1 was 7.3 m 2 / g.
　バインダー樹脂として、フッ化ビニリデン－ヘキサフルオロプロピレン共重合体（アルケマ株式会社製：商品名「ＫＹＮＡＲ２８０１」）を用いた。 As a binder resin, a vinylidene fluoride-hexafluoropropylene copolymer (manufactured by Arkema Ltd .: trade name “KYNAR2801”) was used.
　前記無機フィラー、フッ化ビニリデン－ヘキサフルオロプロピレン共重合体および溶媒（関東化学株式会社製　Ｎ-メチル‐２－ピロリジノン）を、下記割合となるように混合した。すなわち、無機フィラー９０重量部に対してフッ化ビニリデン－ヘキサフルオロプロピレン共重合体１０重量部を混合すると共に、得られる混合液における固形分（無機フィラーおよびフッ化ビニリデン－ヘキサフルオロプロピレン共重合体）の濃度が３７重量％となるように溶媒を混合した。得られた混合液を薄膜旋回型高速ミキサー（プライミクス（株）製フィルミク（登録商標））で攪拌および混合して均一な塗工液１を得た。
　（多孔質層、積層体の製造）
　得られた前記塗工液１を、前記Ａ層の片面にドクターブレード法により、塗工せん断速度３．９（１／ｓ）にて塗工し、前記Ａ層の片面に塗膜を形成した。その後、前記塗膜を、６５℃にて２０分間かけて乾燥することで、前記Ａ層の片面にＢ層を形成した。これによりＡ層の片面にＢ層が積層された積層体１（積層セパレータ）を得た。Ｂ層の目付は７ｇ／ｍ２であり、厚さは４μｍであった。 The inorganic filler, vinylidene fluoride-hexafluoropropylene copolymer and solvent (N-methyl-2-pyrrolidinone manufactured by Kanto Chemical Co., Inc.) were mixed in the following proportions. That is, 10 parts by weight of vinylidene fluoride-hexafluoropropylene copolymer is mixed with 90 parts by weight of inorganic filler, and the solid content in the resulting mixed liquid (inorganic filler and vinylidene fluoride-hexafluoropropylene copolymer). The solvent was mixed so that the concentration of was 37% by weight. The obtained mixed liquid was stirred and mixed with a thin film swivel type high speed mixer (Filmiku (registered trademark) manufactured by Primix Co., Ltd.) to obtain a uniform coating liquid 1.
(Production of porous layer and laminate)
The obtained coating liquid 1 was applied to one surface of the A layer by a doctor blade method at a coating shear rate of 3.9 (1 / s) to form a coating film on one surface of the A layer. .. Then, the coating film was dried at 65 ° C. for 20 minutes to form a B layer on one surface of the A layer. Thus, a laminated body 1 (laminated separator) in which the B layer was laminated on one surface of the A layer was obtained. The weight of the B layer was 7 g / m 2 and the thickness was 4 μm.
　〔非水電解液二次電池の作製〕
　（正極板）
　ＬｉＮｉ０．５Ｍｎ０．３Ｃｏ０．２Ｏ２／導電剤／ＰＶＤＦ（重量比：９２／５／３）の正極合剤が、正極集電体（アルミニウム箔）の片面に積層された正極板を得た。この正極板に対して、室温で３０秒間拘束圧（０．７ＭＰａ）をかけた。 [Preparation of non-aqueous electrolyte secondary battery]
(Positive plate)
A positive electrode in which a positive electrode mixture of LiNi 0.5 Mn 0.3 Co 0.2 O 2 / conductive agent / PVDF (weight ratio: 92/5/3) is laminated on one surface of a positive electrode current collector (aluminum foil). I got a board. A binding pressure (0.7 MPa) was applied to this positive electrode plate at room temperature for 30 seconds.
　前記正極板を、正極活物質層が積層された部分の大きさが４５ｍｍ×３０ｍｍであり、かつその外周に幅１３ｍｍで正極活物質層が積層されていない部分が残るように、切り取ることにより、正極板１を得た。正極活物質層の厚さは３８μｍであった。 By cutting the positive electrode plate so that the size of the portion where the positive electrode active material layer is laminated is 45 mm × 30 mm, and the portion where the positive electrode active material layer is not laminated with a width of 13 mm is left on the outer periphery thereof, A positive electrode plate 1 was obtained. The thickness of the positive electrode active material layer was 38 μm.
　（負極板）
　体積基準の平均粒径（Ｄ５０）が１５μｍである天然黒鉛／スチレン－１，３－ブタジエン共重合体／カルボキシメチルセルロースナトリウム（重量比９８／１／１）の負極合剤が、負極集電体（銅箔）の片面に積層された負極板を得た。この負極板に対して、室温で３０秒間拘束圧（０．７ＭＰａ）をかけた。 (Negative electrode plate)
A negative electrode mixture of natural graphite / styrene-1,3-butadiene copolymer / sodium carboxymethyl cellulose (weight ratio 98/1/1) having a volume-based average particle diameter (D50) of 15 μm was used as a negative electrode current collector ( A negative electrode plate laminated on one surface of the copper foil) was obtained. A binding pressure (0.7 MPa) was applied to this negative electrode plate at room temperature for 30 seconds.
　前記負極板を、負極活物質層が積層された部分の大きさが５０ｍｍ×３５ｍｍであり、かつその外周に幅１３ｍｍで負極活物質層が積層されていない部分が残るように、切り取ることにより、負極板１を得た。負極活物質層の厚さは３８μｍであった。 By cutting the negative electrode plate such that the size of the portion where the negative electrode active material layer is laminated is 50 mm × 35 mm, and the portion where the negative electrode active material layer is not laminated with a width of 13 mm is left on the outer periphery thereof, A negative electrode plate 1 was obtained. The thickness of the negative electrode active material layer was 38 μm.
　（非水電解液二次電池の作製）
　前記正極板１、前記負極板１および積層体１を使用して、以下に示す方法にて非水電解液二次電池を製造した。 (Preparation of non-aqueous electrolyte secondary battery)
A non-aqueous electrolyte secondary battery was manufactured using the positive electrode plate 1, the negative electrode plate 1 and the laminate 1 by the method described below.
　ラミネートパウチ内で、前記正極板１、積層体１および負極板１をこの順で積層（配置）することにより、非水電解液二次電池用部材１を得た。このとき、正極板１の正極活物質層における主面の全部が、負極板１の負極活物質層における主面の範囲に含まれるように、正極板１および負極板１を配置した。すなわち、正極板１の正極活物質層における主面の全部が、負極板１の負極活物質層における主面に重なるように、正極板１および負極板１を配置した。また、積層体１の多孔質層側の面を、正極板１の正極活物質層に対向させた。 By laminating (arranging) the positive electrode plate 1, the laminate 1 and the negative electrode plate 1 in this order in a laminate pouch, a member 1 for a non-aqueous electrolyte secondary battery was obtained. At this time, the positive electrode plate 1 and the negative electrode plate 1 were arranged such that the entire main surface of the positive electrode active material layer of the positive electrode plate 1 was included in the range of the main surface of the negative electrode active material layer of the negative electrode plate 1. That is, the positive electrode plate 1 and the negative electrode plate 1 were arranged so that the entire main surface of the positive electrode active material layer of the positive electrode plate 1 overlaps the main surface of the negative electrode active material layer of the negative electrode plate 1. Further, the surface of the laminated body 1 on the side of the porous layer was opposed to the positive electrode active material layer of the positive electrode plate 1.
　続いて、非水電解液二次電池用部材１を、予め作製していた、アルミニウム層とヒートシール層とが積層されてなる袋に入れ、さらにこの袋に非水電解液を０．２３ｍＬ入れた。前記非水電解液は、エチレンカーボネート、エチルメチルカーボネート、ジエチルカーボネートを３：５：２（体積比）で混合してなる混合溶媒に、ＬｉＰＦ６の濃度が１ｍｏｌ／Ｌとなるように溶解することにより、調製した。そして、袋内を減圧しつつ、当該袋をヒートシールすることにより、非水電解液二次電池１を作製した。 Then, the non-aqueous electrolyte secondary battery member 1 was placed in a previously prepared bag in which an aluminum layer and a heat seal layer were laminated, and 0.23 mL of the non-aqueous electrolyte solution was further placed in this bag. It was The non-aqueous electrolyte solution should be dissolved in a mixed solvent prepared by mixing ethylene carbonate, ethylmethyl carbonate and diethyl carbonate in a volume ratio of 3: 5: 2 so that the concentration of LiPF 6 is 1 mol / L. Was prepared by. Then, the inside of the bag was depressurized and the bag was heat-sealed to manufacture the non-aqueous electrolyte secondary battery 1.
　その後、上述の方法にて得られた非水電解液二次電池１の電池特性の測定を行った。その結果を表１に示す。 After that, the battery characteristics of the non-aqueous electrolyte secondary battery 1 obtained by the above method were measured. The results are shown in Table 1.
　［実施例２］
　〔多孔質層、積層体の作製〕
　無機フィラー２として、球状アルミナ（住友化学株式会社製、商品名ＡＡ０３）およびマイカ（株式会社和光純薬製、商品名：非膨潤性合成雲母）の混合物を用いた。上記混合物は、球状アルミナ５０重量部およびマイカ５０重量部を乳鉢で混合して作製した。無機フィラー２の酸素原子質量百分率は、４５％であった。また、無機フィラー２のＤ５０、Ｄ１０、Ｄ９０は、それぞれ４．２μｍ、０．５μｍ、１１．５μｍであった。さらに、無機フィラー２の単位面積当たりのＢＥＴ比表面積は、４．５ｍ２／ｇであった。 [Example 2]
[Preparation of porous layer and laminate]
As the inorganic filler 2, a mixture of spherical alumina (Sumitomo Chemical Co., Ltd., trade name AA03) and mica (Wako Pure Chemical Industries, Ltd., trade name: non-swelling synthetic mica) was used. The above mixture was prepared by mixing 50 parts by weight of spherical alumina and 50 parts by weight of mica in a mortar. The oxygen atom mass percentage of the inorganic filler 2 was 45%. Further, D50, D10 and D90 of the inorganic filler 2 were 4.2 μm, 0.5 μm and 11.5 μm, respectively. Furthermore, the BET specific surface area per unit area of the inorganic filler 2 was 4.5 m 2 / g.
　塗工液は、以下の通り作製した。すなわち、無機フィラー９０重量部に対してフッ化ビニリデン－ヘキサフルオロプロピレン共重合体１０重量部を混合すると共に、得られる混合液における固形分（無機フィラー＋フッ化ビニリデン－ヘキサフルオロプロピレン共重合体）の濃度が３０重量％となるように溶媒を混合した。得られた混合液を薄膜旋回型高速ミキサーで攪拌および混合して均一な塗工液２を得た。 The coating liquid was prepared as follows. That is, 10 parts by weight of vinylidene fluoride-hexafluoropropylene copolymer was mixed with 90 parts by weight of inorganic filler, and the solid content in the resulting mixed liquid (inorganic filler + vinylidene fluoride-hexafluoropropylene copolymer). The solvent was mixed so that the concentration of was 30% by weight. The obtained mixed liquid was stirred and mixed by a thin film swivel type high speed mixer to obtain a uniform coating liquid 2.
　多孔質層（Ｂ層）の作製に使用した無機フィラー１を上記無機フィラー２に変更し、塗工液１を上記塗工液２に変更し、塗工せん断速度を７．９（１／ｓ）に変更したこと以外は、実施例１と同様にして、積層体２を得た。 The inorganic filler 1 used for producing the porous layer (B layer) was changed to the above inorganic filler 2, the coating liquid 1 was changed to the above coating liquid 2, and the coating shear rate was 7.9 (1 / s). A layered product 2 was obtained in the same manner as in Example 1 except that the content was changed to).
　〔非水電解液二次電池の作製〕
　積層体１の代わりに、積層体２を使用したこと以外は、実施例１と同様にして、非水電解液二次電池２を得た。 [Preparation of non-aqueous electrolyte secondary battery]
A non-aqueous electrolyte secondary battery 2 was obtained in the same manner as in Example 1 except that the laminate 2 was used instead of the laminate 1.
　その後、上述の方法にて得られた非水電解液二次電池２の電池特性の測定を行った。その結果を表１に示す。 After that, the battery characteristics of the non-aqueous electrolyte secondary battery 2 obtained by the above method were measured. The results are shown in Table 1.
　［実施例３］
　〔多孔質層、積層体の作製〕
　無機フィラー３として、酸素原子質量百分率４２％であるワラストナイト（林化成株式会社製、商品名：ワラストナイト　ＶＭ－８Ｎ）を用いた。無機フィラー３のＤ５０、Ｄ１０、Ｄ９０は、それぞれ１０．６μｍ、２．４μｍ、２５．３μｍであった。また、無機フィラー３の単位面積当たりのＢＥＴ比表面積は、１．３ｍ２／ｇであった。 [Example 3]
[Preparation of porous layer and laminate]
As the inorganic filler 3, wollastonite (Hayashi Kasei Co., Ltd., trade name: Wollastonite VM-8N) having an oxygen atomic mass percentage of 42% was used. D50, D10, and D90 of the inorganic filler 3 were 10.6 μm, 2.4 μm, and 25.3 μm, respectively. The BET specific surface area per unit area of the inorganic filler 3 was 1.3 m 2 / g.
　塗工液は、以下の通り作製した。すなわち、無機フィラー９０重量部に対してフッ化ビニリデン－ヘキサフルオロプロピレン共重合体１０重量部を混合すると共に、得られる混合液における固形分（無機フィラー＋フッ化ビニリデン－ヘキサフルオロプロピレン共重合体）の濃度が４０重量％となるように溶媒を混合した。得られた混合液を薄膜旋回型高速ミキサーで攪拌および混合して均一な塗工液３を得た。 The coating liquid was prepared as follows. That is, 10 parts by weight of vinylidene fluoride-hexafluoropropylene copolymer was mixed with 90 parts by weight of inorganic filler, and the solid content in the resulting mixed liquid (inorganic filler + vinylidene fluoride-hexafluoropropylene copolymer). The solvent was mixed so that the concentration of was 40% by weight. The obtained mixed liquid was stirred and mixed with a thin film swivel type high speed mixer to obtain a uniform coating liquid 3.
　多孔質層（Ｂ層）の作製に使用した無機フィラー１を上記無機フィラー３に変更し、塗工液１を上記塗工液３に変更し、塗工せん断速度を７．９（１／ｓ）に変更したこと以外は、実施例１と同様にして、積層体３を得た。 The inorganic filler 1 used in the preparation of the porous layer (B layer) was changed to the above inorganic filler 3, the coating liquid 1 was changed to the above coating liquid 3, and the coating shear rate was 7.9 (1 / s A laminated body 3 was obtained in the same manner as in Example 1 except that the layer structure 3 was changed to).
　〔非水電解液二次電池の作製〕
　積層体１の代わりに、積層体３を使用したこと以外は、実施例１と同様にして、非水電解液二次電池３を得た。 [Preparation of non-aqueous electrolyte secondary battery]
A non-aqueous electrolyte secondary battery 3 was obtained in the same manner as in Example 1 except that the laminate 3 was used instead of the laminate 1.
　その後、上述の方法にて得られた非水電解液二次電池３の電池特性の測定を行った。その結果を表１に示す。 After that, the battery characteristics of the non-aqueous electrolyte secondary battery 3 obtained by the above method were measured. The results are shown in Table 1.
　［実施例４］
　〔多孔質層、積層体の作製〕
　無機フィラー４として、αアルミナ（住友化学株式会社製、商品名：ＡＫＰ３０００）および六角板状酸化亜鉛（堺化学工業株式会社製、商品名：ＸＺ－１０００Ｆ）の混合物を用いた。上記混合物は、αアルミナ９９重量部および六角板状酸化亜鉛１重量部を乳鉢で混合して作製した。無機フィラー４の酸素原子質量百分率は、４７％であった。また、無機フィラー４のＤ５０、Ｄ１０、Ｄ９０は、それぞれ０．８μｍ、０．４μｍ、２．２μｍであった。さらに、無機フィラー４の単位面積当たりのＢＥＴ比表面積は、４．５ｍ２／ｇであった。 [Example 4]
[Preparation of porous layer and laminate]
As the inorganic filler 4, a mixture of α-alumina (Sumitomo Chemical Co., Ltd., trade name: AKP3000) and hexagonal plate-shaped zinc oxide (Sakai Chemical Industry Co., Ltd., trade name: XZ-1000F) was used. The above mixture was prepared by mixing 99 parts by weight of α-alumina and 1 part by weight of hexagonal plate-shaped zinc oxide in a mortar. The oxygen atom mass percentage of the inorganic filler 4 was 47%. Further, D50, D10, and D90 of the inorganic filler 4 were 0.8 μm, 0.4 μm, and 2.2 μm, respectively. Furthermore, the BET specific surface area per unit area of the inorganic filler 4 was 4.5 m 2 / g.
　塗工液は、以下の通り作製した。すなわち、無機フィラー９０重量部に対してフッ化ビニリデン－ヘキサフルオロプロピレン共重合体１０重量部を混合すると共に、得られる混合液における固形分（無機フィラー＋フッ化ビニリデン－ヘキサフルオロプロピレン共重合体）の濃度が４０重量％となるように溶媒を混合した。得られた混合液を薄膜旋回型高速ミキサーで攪拌および混合して均一な塗工液４を得た。 The coating liquid was prepared as follows. That is, 10 parts by weight of vinylidene fluoride-hexafluoropropylene copolymer was mixed with 90 parts by weight of inorganic filler, and the solid content in the resulting mixed liquid (inorganic filler + vinylidene fluoride-hexafluoropropylene copolymer). The solvent was mixed so that the concentration of was 40% by weight. The obtained mixed liquid was stirred and mixed by a thin film swivel type high speed mixer to obtain a uniform coating liquid 4.
　多孔質層（Ｂ層）の作製に使用した無機フィラー１を上記無機フィラー４に変更し、塗工液１を上記塗工液４に変更し、塗工せん断速度を３９．４（１／ｓ）に変更したこと以外は、実施例１と同様にして、積層体４を得た。 The inorganic filler 1 used for producing the porous layer (B layer) was changed to the above inorganic filler 4, the coating liquid 1 was changed to the above coating liquid 4, and the coating shear rate was 39.4 (1 / s). A layered product 4 was obtained in the same manner as in Example 1 except that the content was changed to).
　（正極板）
　ＬｉＮｉ０．５Ｍｎ０．３Ｃｏ０．２Ｏ２／導電剤／ＰＶＤＦ（重量比：９２／５／３）の正極合剤が、正極集電体（アルミニウム箔）の片面に積層された正極板を得た。この正極板をジエチルカーボネートで湿潤させた状態で、室温で３０秒間拘束圧（０．７ＭＰａ）をかけた。 (Positive plate)
A positive electrode in which a positive electrode mixture of LiNi 0.5 Mn 0.3 Co 0.2 O 2 / conductive agent / PVDF (weight ratio: 92/5/3) is laminated on one surface of a positive electrode current collector (aluminum foil). I got a board. A binding pressure (0.7 MPa) was applied at room temperature for 30 seconds while the positive electrode plate was wet with diethyl carbonate.
　前記正極板を、正極活物質層が積層された部分の大きさが４５ｍｍ×３０ｍｍであり、かつその外周に幅１３ｍｍで正極活物質層が積層されていない部分が残るように、切り取ることにより、正極板２を得た。正極活物質層の厚さは３７μｍであった。 By cutting the positive electrode plate so that the size of the portion where the positive electrode active material layer is laminated is 45 mm × 30 mm, and the portion where the positive electrode active material layer is not laminated with a width of 13 mm is left on the outer periphery thereof, A positive electrode plate 2 was obtained. The thickness of the positive electrode active material layer was 37 μm.
　〔非水電解液二次電池の作製〕
　積層体１の代わりに積層体４を使用し、正極板として前記正極板２を使用したこと以外は、実施例１と同様にして、非水電解液二次電池４を得た。 [Preparation of non-aqueous electrolyte secondary battery]
A non-aqueous electrolyte secondary battery 4 was obtained in the same manner as in Example 1 except that the laminate 4 was used instead of the laminate 1 and the positive electrode plate 2 was used as the positive electrode plate.
　その後、上述の方法にて得られた非水電解液二次電池４の電池特性の測定を行った。その結果を表１に示す。 After that, the battery characteristics of the non-aqueous electrolyte secondary battery 4 obtained by the above method were measured. The results are shown in Table 1.
　［実施例５］
　（正極板）
　正極合剤（ＬｉＣｏＯ２／導電剤／ＰＶＤＦ（重量比：１００／５／３））が、正極集電体（アルミニウム箔）の片面に積層された正極板を得た。この正極板をジエチルカーボネートで湿潤させた状態で、室温で３０秒間拘束圧（０．７ＭＰａ）をかけた。 [Example 5]
(Positive plate)
A positive electrode plate was obtained in which the positive electrode mixture (LiCoO 2 / conductive agent / PVDF (weight ratio: 100/5/3)) was laminated on one surface of the positive electrode current collector (aluminum foil). A binding pressure (0.7 MPa) was applied at room temperature for 30 seconds while the positive electrode plate was wet with diethyl carbonate.
　前記正極板を、正極活物質層が積層された部分の大きさが４５ｍｍ×３０ｍｍであり、かつその外周に幅１３ｍｍで正極活物質層が積層されていない部分が残るように、切り取ることにより正極板３を得た。正極活物質層の厚さは３８μｍであった。 The positive electrode plate is cut so that the size of the part where the positive electrode active material layer is laminated is 45 mm × 30 mm, and the part where the positive electrode active material layer is not laminated is left on the outer periphery of the positive electrode plate so as to remain. Board 3 was obtained. The thickness of the positive electrode active material layer was 38 μm.
　［非水電解液二次電池の作製］
　積層体１の代わりに積層体４を使用し、正極板として前記正極板３を使用したこと以外は、実施例１と同様にして、非水電解液二次電池５を得た。 [Preparation of non-aqueous electrolyte secondary battery]
A non-aqueous electrolyte secondary battery 5 was obtained in the same manner as in Example 1 except that the laminate 4 was used instead of the laminate 1 and the positive electrode plate 3 was used as the positive electrode plate.
　その後、上述の方法にて得られた非水電解液二次電池５の電池特性の測定を行った。その結果を表１に示す。 After that, the battery characteristics of the non-aqueous electrolyte secondary battery 5 obtained by the above method were measured. The results are shown in Table 1.
　［実施例６］
　（負極板）
　天然黒鉛／スチレン－１，３－ブタジエン共重合体／カルボキシメチルセルロースナトリウム（重量比９８／１／１）の負極合剤が、負極集電体（銅箔）の片面に積層された負極板を得た。この負極板をジエチルカーボネートで湿潤した状態で、室温で３０秒間拘束圧（０．７ＭＰａ）をかけた。 [Example 6]
(Negative electrode plate)
A negative electrode plate in which a negative electrode mixture of natural graphite / styrene-1,3-butadiene copolymer / sodium carboxymethyl cellulose (weight ratio 98/1/1) was laminated on one side of a negative electrode current collector (copper foil) It was A binding pressure (0.7 MPa) was applied for 30 seconds at room temperature while the negative electrode plate was wet with diethyl carbonate.
　前記負極板を、負極活物質層が積層された部分の大きさが５０ｍｍ×３５ｍｍであり、かつその外周に幅１３ｍｍで負極活物質層が積層されていない部分が残るように、切り取ることにより、負極板２を得た。負極活物質層の厚さは３７μｍであった。 By cutting the negative electrode plate such that the size of the portion where the negative electrode active material layer is laminated is 50 mm × 35 mm, and the portion where the negative electrode active material layer is not laminated with a width of 13 mm is left on the outer periphery thereof, A negative electrode plate 2 was obtained. The thickness of the negative electrode active material layer was 37 μm.
　〔非水電解液二次電池の作製〕
　積層体１の代わりに積層体４を使用し、負極板として前記負極板２を使用したこと以外は、実施例１と同様にして、非水電解液二次電池６を得た。 [Preparation of non-aqueous electrolyte secondary battery]
A non-aqueous electrolyte secondary battery 6 was obtained in the same manner as in Example 1 except that the laminate 4 was used instead of the laminate 1 and the negative electrode plate 2 was used as the negative electrode plate.
　その後、上述の方法にて得られた非水電解液二次電池６の電池特性の測定を行った。その結果を表１に示す。 After that, the battery characteristics of the non-aqueous electrolyte secondary battery 6 obtained by the above method were measured. The results are shown in Table 1.
　［実施例７］
　（負極板）
　人造球晶黒鉛／導電剤／ＰＶＤＦ（重量比８５／１５／７．５）の負極合剤が、負極集電体（銅箔）の片面に積層された負極板を得た。この負極板をジエチルカーボネートで湿潤させた状態で、室温で３０秒間拘束圧（０．７ＭＰａ）をかけた。 [Example 7]
(Negative electrode plate)
A negative electrode plate was obtained in which a negative electrode mixture of artificial spherulite graphite / conductive agent / PVDF (weight ratio 85/15 / 7.5) was laminated on one surface of a negative electrode current collector (copper foil). A binding pressure (0.7 MPa) was applied for 30 seconds at room temperature while the negative electrode plate was wet with diethyl carbonate.
　前記負極板を、負極活物質層が積層された部分の大きさが５０ｍｍ×３５ｍｍであり、かつその外周に幅１３ｍｍで負極活物質層が積層されていない部分が残るように、切り取ることにより、負極板３を得た。負極活物質層の厚さは３６μｍであった。 By cutting the negative electrode plate such that the size of the portion where the negative electrode active material layer is laminated is 50 mm × 35 mm, and the portion where the negative electrode active material layer is not laminated with a width of 13 mm is left on the outer periphery thereof, A negative electrode plate 3 was obtained. The thickness of the negative electrode active material layer was 36 μm.
　〔非水電解液二次電池の作製〕
　積層体１の代わりに積層体４を使用し、負極板として前記負極板３を使用したこと以外は、実施例１と同様にして、非水電解液二次電池７を得た。 [Preparation of non-aqueous electrolyte secondary battery]
A non-aqueous electrolyte secondary battery 7 was obtained in the same manner as in Example 1 except that the laminate 4 was used instead of the laminate 1 and the negative electrode plate 3 was used as the negative electrode plate.
　その後、上述の方法にて得られた非水電解液二次電池７の電池特性の測定を行った。その結果を表１に示す。 After that, the battery characteristics of the non-aqueous electrolyte secondary battery 7 obtained by the above method were measured. The results are shown in Table 1.
　［比較例１］
　〔多孔質層、積層体の作製〕
　無機フィラー５として、酸素原子質量百分率７１％であるホウ砂（和光純薬製）を用いた。無機フィラー５のＤ５０、Ｄ１０、Ｄ９０は、それぞれ２７μｍ、６．３μｍ、１１１μｍであった。また、無機フィラー５の単位面積当たりのＢＥＴ比表面積は、２．５ｍ２／ｇであった。 [Comparative Example 1]
[Preparation of porous layer and laminate]
As the inorganic filler 5, borax (manufactured by Wako Pure Chemical Industries, Ltd.) having an oxygen atomic mass percentage of 71% was used. D50, D10, and D90 of the inorganic filler 5 were 27 μm, 6.3 μm, and 111 μm, respectively. The BET specific surface area per unit area of the inorganic filler 5 was 2.5 m 2 / g.
　塗工液は、以下の通り作製した。すなわち、無機フィラー９０重量部に対してフッ化ビニリデン－ヘキサフルオロプロピレン共重合体１０重量部を混合すると共に、得られる混合液における固形分（無機フィラー＋フッ化ビニリデン－ヘキサフルオロプロピレン共重合体）の濃度が４０重量％となるように溶媒を混合した。得られた混合液を薄膜旋回型高速ミキサーで攪拌および混合して均一な塗工液５を得た。 The coating liquid was prepared as follows. That is, 10 parts by weight of vinylidene fluoride-hexafluoropropylene copolymer was mixed with 90 parts by weight of inorganic filler, and the solid content in the resulting mixed liquid (inorganic filler + vinylidene fluoride-hexafluoropropylene copolymer). The solvent was mixed so that the concentration of was 40% by weight. The obtained mixed liquid was stirred and mixed by a thin film swivel type high speed mixer to obtain a uniform coating liquid 5.
　多孔質層（Ｂ層）の作製に使用した無機フィラー１を上記無機フィラー５に変更し、塗工液１を上記塗工液５に変更し、塗工せん断速度を７．９（１／ｓ）に変更したこと以外は、実施例１と同様にして、積層体５を得た。 The inorganic filler 1 used in the preparation of the porous layer (B layer) was changed to the above inorganic filler 5, the coating liquid 1 was changed to the above coating liquid 5, and the coating shear rate was 7.9 (1 / s A layered product 5 was obtained in the same manner as in Example 1 except that the content was changed to).
　〔非水電解液二次電池の作製〕
　積層体１の代わりに積層体５を使用したこと以外は、実施例１と同様にして、非水電解液二次電池８を得た。 [Preparation of non-aqueous electrolyte secondary battery]
A non-aqueous electrolyte secondary battery 8 was obtained in the same manner as in Example 1 except that the laminate 5 was used instead of the laminate 1.
　その後、上述の方法にて得られた非水電解液二次電池８の電池特性の測定を行った。その結果を表１に示す。 After that, the battery characteristics of the non-aqueous electrolyte secondary battery 8 obtained by the above method were measured. The results are shown in Table 1.
　［比較例２］
　（正極板）
　ＬｉＮｉ０．５Ｍｎ０．３Ｃｏ０．２Ｏ２／導電剤／ＰＶＤＦ（重量比：９２／５／３）の正極合剤が、正極集電体（アルミニウム箔）の片面に積層された正極板を得た。 [Comparative Example 2]
(Positive plate)
A positive electrode in which a positive electrode mixture of LiNi 0.5 Mn 0.3 Co 0.2 O 2 / conductive agent / PVDF (weight ratio: 92/5/3) is laminated on one surface of a positive electrode current collector (aluminum foil). I got a board.
　前記正極板を、正極活物質層が積層された部分の大きさが４５ｍｍ×３０ｍｍであり、かつその外周に幅１３ｍｍで正極活物質層が積層されていない部分が残るように、切り取ることにより、正極板４とした。正極活物質層の厚さは３８μｍであった。 By cutting the positive electrode plate so that the size of the portion where the positive electrode active material layer is laminated is 45 mm × 30 mm, and the portion where the positive electrode active material layer is not laminated with a width of 13 mm is left on the outer periphery thereof, The positive electrode plate 4 was used. The thickness of the positive electrode active material layer was 38 μm.
　〔非水電解液二次電池の作製〕
　積層体１の代わりに積層体４を使用し、正極板として前記正極板４を使用したこと以外は、実施例１と同様にして、非水電解液二次電池９を得た。 [Preparation of non-aqueous electrolyte secondary battery]
A non-aqueous electrolyte secondary battery 9 was obtained in the same manner as in Example 1 except that the laminate 4 was used instead of the laminate 1 and the positive electrode plate 4 was used as the positive electrode plate.
　その後、上述の方法にて得られた非水電解液二次電池９の電池特性の測定を行った。その結果を表１に示す。 After that, the battery characteristics of the non-aqueous electrolyte secondary battery 9 obtained by the above method were measured. The results are shown in Table 1.
　［比較例３］
　（負極板）
　天然黒鉛／スチレン－１，３－ブタジエン共重合体／カルボキシメチルセルロースナトリウム（重量比９８／１／１）の負極合剤が、負極集電体（銅箔）の片面に積層された負極板を得た。 [Comparative Example 3]
(Negative electrode plate)
A negative electrode plate in which a negative electrode mixture of natural graphite / styrene-1,3-butadiene copolymer / sodium carboxymethyl cellulose (weight ratio 98/1/1) was laminated on one side of a negative electrode current collector (copper foil) It was
　前記負極板を、負極活物質層が積層された部分の大きさが５０ｍｍ×３５ｍｍであり、かつその外周に幅１３ｍｍで負極活物質層が積層されていない部分が残るように、切り取ることにより、負極板４とした。負極活物質層の厚さは３８μｍであった。 By cutting the negative electrode plate such that the size of the portion where the negative electrode active material layer is laminated is 50 mm × 35 mm, and the portion where the negative electrode active material layer is not laminated with a width of 13 mm is left on the outer periphery thereof, The negative electrode plate 4 was used. The thickness of the negative electrode active material layer was 38 μm.
　〔非水電解液二次電池の作製〕
　積層体１の代わりに積層体４を使用し、負極板として前記負極板４を使用したこと以外は、実施例１と同様にして、非水電解液二次電池１０を得た。 [Preparation of non-aqueous electrolyte secondary battery]
A non-aqueous electrolyte secondary battery 10 was obtained in the same manner as in Example 1 except that the laminate 4 was used instead of the laminate 1 and the negative electrode plate 4 was used as the negative electrode plate.
　その後、上述の方法にて得られた非水電解液二次電池１０の電池特性の測定を行った。その結果を表１に示す。 After that, the battery characteristics of the non-aqueous electrolyte secondary battery 10 obtained by the above method were measured. The results are shown in Table 1.
　なお、表１において、実施例２および４～７、ならびに比較例２～３の「無機フィラー」欄には、二種類の化合物および数値が記載されている。当該数値は、化合物の重量部を表している。例えば、実施例２には、「Ａｌ２Ｏ３／マイカ　５０／５０」と記載されており、これは、Ａｌ２Ｏ３を５０重量部、マイカを５０重量部用いたことを表している。 In Table 1, two types of compounds and numerical values are described in the “inorganic filler” column of Examples 2 and 4 to 7 and Comparative Examples 2 to 3. The numerical value represents the weight part of the compound. For example, in Example 2, "Al 2 O 3 / mica 50/50" is described, which means that 50 parts by weight of Al 2 O 3 and 50 parts by weight of mica were used.
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
　［結論］
　表１に示されるように、実施例１～７の非水電解液二次電池は、比較例１～３の非水電解液二次電池に比べて充放電サイクル後の放電容量回復特性に優れていることがわかった。実施例１～７の非水電解液二次電池は、正極板の電極活物質層が剥がれるまでの折り曲げ回数が１３０回以上であり、負極板の電極活物質層が剥がれるまでの折り曲げ回数が１６５０回以上であり、多孔質層の｜１－Ｔ／Ｍ｜で表される値が、０．１０～０．４２の範囲にある。一方、比較例１は、｜１－Ｔ／Ｍ｜が０．４２を超えている。比較例２は、正極板の電極活物質層が剥がれるまでの折り曲げ回数が１３０回未満である。比較例３は、負極板の電極活物質層が剥がれるまでの折り曲げ回数が１６５０回未満である。 [Conclusion]
As shown in Table 1, the non-aqueous electrolyte secondary batteries of Examples 1 to 7 have excellent discharge capacity recovery characteristics after charge / discharge cycles as compared with the non-aqueous electrolyte secondary batteries of Comparative Examples 1 to 3. I found out. In the non-aqueous electrolyte secondary batteries of Examples 1 to 7, the number of folds until the electrode active material layer of the positive electrode plate was peeled was 130 times or more, and the number of folds until the electrode active material layer of the negative electrode plate was peeled was 1650. It is more than once, and the value represented by | 1-T / M | of the porous layer is in the range of 0.10 to 0.42. On the other hand, in Comparative Example 1, | 1-T / M | exceeds 0.42. In Comparative Example 2, the number of bending times before peeling off the electrode active material layer of the positive electrode plate was less than 130 times. In Comparative Example 3, the number of times of bending until the electrode active material layer of the negative electrode plate was peeled off was less than 1650.
　本発明の一実施形態に係る非水電解液二次電池は、充放電サイクル後の放電容量回復特性に優れるため、パーソナルコンピュータ、携帯電話および携帯情報端末等に用いる電池、ならびに車載用電池として好適に利用することができる。 The non-aqueous electrolyte secondary battery according to an embodiment of the present invention is excellent in discharge capacity recovery characteristics after charge / discharge cycles, and thus is suitable as a battery used for personal computers, mobile phones, personal digital assistants, and the like, and a vehicle battery. Can be used for.
　１　ダイヤモンド圧子
　２　基板
　３　積層体 1 Diamond indenter 2 Substrate 3 Laminate

Claims (5)

  1. 　無機フィラーと樹脂とを含む多孔質層と、
    　ＪＩＳ　Ｐ　８１１５（１９９４）に規定されたＭＩＴ試験機法に準拠し、荷重１Ｎ、折り曲げ角度４５°にて実施した耐折試験において、電極活物質層が剥がれるまでの折り曲げ回数が１３０回以上である正極板と、
    　前記耐折試験において、電極活物質層が剥がれるまでの折り曲げ回数が１６５０回以上である負極板と、を備え、
    　前記多孔質層は、下記式（１）で表される値が、０．１０～０．４２の範囲にある、非水電解液二次電池。
    ｜１－Ｔ／Ｍ｜・・・（１）
    （式（１）中、Ｔは、ＴＤにおける０．１Ｎの一定荷重下でのスクラッチ試験における、臨界荷重までの距離を表し、Ｍは、ＭＤにおける０．１Ｎの一定荷重下でのスクラッチ試験における、臨界荷重までの距離を表す。）     A porous layer containing an inorganic filler and a resin,
    In a folding endurance test carried out at a load of 1 N and a bending angle of 45 ° in accordance with the MIT tester method defined in JIS P 8115 (1994), the number of times of bending until the electrode active material layer is peeled is 130 times or more. A positive electrode plate,
    In the folding endurance test, a negative electrode plate having a bending frequency of 1650 or more before the electrode active material layer is peeled off,
    The non-aqueous electrolyte secondary battery in which the porous layer has a value represented by the following formula (1) in the range of 0.10 to 0.42.
    | 1-T / M | ... (1)
    (In Formula (1), T represents a distance to a critical load in a scratch test under a constant load of 0.1 N in TD, and M represents a scratch test under a constant load of 0.1 N in MD. , Represents the distance to the critical load.)
  2. 　前記多孔質層が、ポリオレフィン、（メタ）アクリレート系樹脂、含フッ素樹脂、ポリアミド系樹脂、ポリエステル系樹脂および水溶性ポリマーからなる群より１種以上選択される樹脂を含む、請求項１に記載の非水電解液二次電池。 2. The porous layer according to claim 1, wherein the porous layer contains a resin selected from the group consisting of a polyolefin, a (meth) acrylate resin, a fluorine-containing resin, a polyamide resin, a polyester resin, and a water-soluble polymer. Non-aqueous electrolyte secondary battery.
  3. 　前記ポリアミド系樹脂がアラミド樹脂である、請求項２に記載の非水電解液二次電池。 The non-aqueous electrolyte secondary battery according to claim 2, wherein the polyamide resin is an aramid resin.
  4. 　前記多孔質層が、ポリオレフィン多孔質フィルムの片面または両面に積層されている、請求項１～３のいずれか１項に記載の非水電解液二次電池。 The non-aqueous electrolyte secondary battery according to any one of claims 1 to 3, wherein the porous layer is laminated on one side or both sides of a polyolefin porous film.
  5. 　前記正極板が、遷移金属酸化物を含み、前記負極板が、黒鉛を含む、請求項１～４のいずれか１項に記載の非水電解液二次電池。 The nonaqueous electrolyte secondary battery according to any one of claims 1 to 4, wherein the positive electrode plate contains a transition metal oxide and the negative electrode plate contains graphite.
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