WO2017014222A1 - Batterie secondaire au lithium-ion - Google Patents

Batterie secondaire au lithium-ion Download PDF

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Publication number
WO2017014222A1
WO2017014222A1 PCT/JP2016/071188 JP2016071188W WO2017014222A1 WO 2017014222 A1 WO2017014222 A1 WO 2017014222A1 JP 2016071188 W JP2016071188 W JP 2016071188W WO 2017014222 A1 WO2017014222 A1 WO 2017014222A1
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positive electrode
layer
negative electrode
ion secondary
secondary battery
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PCT/JP2016/071188
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English (en)
Japanese (ja)
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伊藤　真吾
学 落田
翔 檜山
葉介 中林
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日立化成株式会社
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Priority to JP2017529901A priority Critical patent/JPWO2017014222A1/ja
Publication of WO2017014222A1 publication Critical patent/WO2017014222A1/fr

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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
    • 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
    • H01M10/0568—Liquid materials characterised by the solutes
    • 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
    • H01M10/0569—Liquid materials characterised by the solvents
    • 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
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/50—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of manganese
    • H01M4/505—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of manganese of mixed oxides or hydroxides containing manganese for inserting or intercalating light metals, e.g. LiMn2O4 or LiMn2OxFy
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/52—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron
    • H01M4/525—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron of mixed oxides or hydroxides containing iron, cobalt or nickel for inserting or intercalating light metals, e.g. LiNiO2, LiCoO2 or LiCoOxFy
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
    • H01M4/583—Carbonaceous material, e.g. graphite-intercalation compounds or CFx
    • H01M4/587—Carbonaceous material, e.g. graphite-intercalation compounds or CFx for inserting or intercalating light metals
    • 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
    • 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 lithium ion secondary battery.
  • non-aqueous electrolyte secondary batteries particularly lithium ion secondary batteries
  • batteries having a high energy density are highly expected as batteries having a high energy density.
  • the energy of lithium ion secondary batteries increases, ensuring safety is an issue.
  • a separator disposed between a positive electrode and a negative electrode uses a nonwoven fabric using a fiber containing polyethylene terephthalate, a polyethylene microfiber
  • a lithium ion secondary battery comprising a porous membrane and having a nonwoven fabric disposed on the negative electrode side of the separator is described.
  • An object of the present invention is to provide a lithium ion secondary battery having excellent high-load discharge characteristics and safety in an overcharged state.
  • Means for solving the above problems include the following embodiments. ⁇ 1> A positive electrode, a negative electrode, a separator disposed between the positive electrode and the negative electrode, and a non-aqueous electrolyte,
  • the separator includes a first layer containing a polyolefin resin, and a second layer containing at least one selected from the group consisting of polyethylene resin, polypropylene resin, polyethylene terephthalate resin, polyvinyl alcohol resin, polyacrylonitrile resin, and aramid resin.
  • the second layer has a lower air permeability than the first layer and is disposed closer to the positive electrode than the first layer.
  • the nonaqueous electrolytic solution includes a cyclic carbonate ( ⁇ ), a chain carbonate ( ⁇ ), and a lithium salt, and a volume ratio ( ⁇ / ⁇ ) of ⁇ and ⁇ is 20/80 to 40/60,
  • the positive electrode includes layered lithium / nickel / manganese / cobalt composite oxide (NMC) as a positive electrode active material, and the negative electrode includes amorphous carbon as a negative electrode active material.
  • NMC nickel / manganese / cobalt composite oxide
  • a lithium ion secondary battery excellent in high load discharge characteristics and safety in an overcharged state is provided.
  • the term “process” includes a process that is independent of other processes and includes the process if the purpose of the process is achieved even if it cannot be clearly distinguished from the other processes. It is.
  • numerical values indicated by using “to” include numerical values described before and after “to” as the minimum value and the maximum value, respectively.
  • the upper limit value or the lower limit value described in one numerical range may be replaced with the upper limit value or the lower limit value of another numerical range. Good. Further, in the numerical ranges described in this specification, the upper limit value or the lower limit value of the numerical range may be replaced with the values shown in the examples.
  • each component in the composition is the sum of the plurality of substances present in the composition unless there is a specific indication when there are a plurality of substances corresponding to each component in the composition. It means the content rate of.
  • the particle diameter of each component in the composition is a mixture of the plurality of types of particles present in the composition unless there is a specific indication when there are a plurality of types of particles corresponding to each component in the composition. Means the value of.
  • the term “layer” refers to the case where the layer is formed only in a part of the region in addition to the case where the layer is formed over the entire region. Is also included.
  • the lithium ion secondary battery according to the present embodiment includes a positive electrode, a negative electrode, a separator disposed between the positive electrode and the negative electrode, and a non-aqueous electrolyte, wherein the separator includes a first polyolefin resin. And a second layer containing at least one selected from the group consisting of a polyethylene resin, a polypropylene resin, a polyethylene terephthalate resin, a polyvinyl alcohol resin, a polyacrylonitrile resin, and an aramid resin, The air permeability is smaller than that of the first layer, and the gas is disposed closer to the positive electrode than the first layer.
  • the separator of the lithium ion secondary battery includes a first layer containing a polyolefin resin, and a group consisting of a polyethylene resin, a polypropylene resin, a polyethylene terephthalate resin, a polyvinyl alcohol resin, a polyacrylonitrile resin, and an aramid resin.
  • a second layer containing at least one selected from the second layer, the second layer has a lower air permeability than the first layer, and the second layer is a positive electrode than the first layer. It has been found that it is excellent in high load discharge characteristics and safety in an overcharged state by being arranged at a position close to.
  • the positive electrode, the negative electrode, the electrolytic solution, the separator, and other components that are components of the lithium ion secondary battery of the present embodiment will be described.
  • the positive electrode (positive electrode plate) includes a current collector and a positive electrode mixture layer (positive electrode mixture layer) formed on at least one surface thereof.
  • the positive electrode mixture layer is a layer containing a positive electrode active material, a binder, and a conductive material, a thickener, and the like used as necessary.
  • the positive electrode active material is not particularly limited, and examples thereof include lithium-containing composite metal oxides (including olivine-type lithium salts such as LiFePO 4 ), chalcogen compounds, and manganese dioxide.
  • a positive electrode active material may be used individually by 1 type, or may use 2 or more types together.
  • the lithium-containing composite metal oxide is a metal oxide containing lithium and a metal other than lithium.
  • metals other than lithium include Na, Mg, Sc, Y, Mn, Fe, Co, Ni, Cu, Zn, Al, Cr, Pb, Sb, and B. Mn, Al, Co, Ni And at least one selected from the group consisting of Mg and Mg is preferred.
  • the metal other than lithium contained in the lithium-containing composite metal oxide may be one type or two or more types.
  • the lithium-containing composite metal oxide is preferably a metal oxide containing lithium and a transition metal. In the metal oxide containing lithium and a transition metal, a part of the transition metal may be substituted with a metal (heterogeneous element) other than the transition metal. Examples of the different element include metals other than lithium listed above that do not correspond to transition metals.
  • x value which shows the molar ratio of lithium increases / decreases by charging / discharging.
  • the chalcogen compound include titanium disulfide and molybdenum disulfide.
  • layered lithium-nickel-manganese-cobalt composite oxide is included as the positive electrode active material from the viewpoint of increasing capacity and extending the life.
  • NMC layered lithium-nickel-manganese-cobalt composite oxide
  • the content is preferably 50% by mass or more of the whole positive electrode active material, more preferably 70% by mass or more, and further preferably 90% by mass or more. .
  • the method for forming the positive electrode mixture layer is not particularly limited. For example, it is formed by a dry method or a wet method.
  • a positive electrode active material, a binder, and other materials such as a conductive material and a thickener used as needed are mixed without using a dispersion solvent to form a sheet, which is used as a current collector.
  • Crimp In the wet method, a positive electrode active material, a binder, and other materials such as a conductive material and a thickener used as necessary are dissolved or dispersed in a dispersion solvent to form a slurry, which is applied to a current collector. ,dry.
  • the positive electrode active material is generally in the form of particles, and examples of the particle shape include a lump shape, a polyhedron shape, a spherical shape, an elliptical spherical shape, a plate shape, a needle shape, and a column shape.
  • the median diameter d50 of the positive electrode active material particles (in the case where the primary particles aggregate to form secondary particles), the median diameter d50 of the secondary particles can be adjusted within the following range. From the viewpoint of obtaining a desired tap density without the tap density (fillability) of the positive electrode active material being too low, D50 of the positive electrode active material is preferably 1 ⁇ m or more, more preferably 3 ⁇ m or more, and more preferably 5 ⁇ m or more. More preferably.
  • the positive electrode is preferably 30 ⁇ m or less, more preferably 25 ⁇ m or less, and even more preferably 15 ⁇ m or less.
  • the median diameter D50 is a value when the integration on the small diameter side is 50% in the volume-based particle size distribution obtained by the laser diffraction / scattering method.
  • the BET specific surface area of the positive electrode active material particles is preferably 0.2 m 2 / g or more, more preferably 0.3 m 2 / g or more, from the viewpoint of suppressing a decrease in battery performance. More preferably, it is 4 m 2 / g or more. Further, from the viewpoint of suppressing a decrease in miscibility with other materials such as a binder and a conductive material, it is preferably 4.0 m 2 / g or less, and is 2.5 m 2 / g or less. More preferably, it is still more preferably 1.5 m 2 / g or less.
  • the BET specific surface area is a specific surface area (area per unit g) determined by the BET method.
  • the conductive material is not particularly limited, and is a metal material such as copper or nickel; graphite such as natural graphite or artificial graphite; graphite black such as acetylene black; needle coke or the like Examples thereof include carbonaceous materials such as amorphous carbon. These conductive materials may be used alone or in combination of two or more.
  • the binder used for the positive electrode mixture layer is not particularly limited.
  • the binder include resin-based polymers such as polyethylene, polypropylene, polyethylene terephthalate, polymethyl methacrylate, polyimide, aromatic polyamide, cellulose, and nitrocellulose; SBR (styrene-butadiene rubber), NBR (acrylonitrile-butadiene) Rubber), fluoropolymer, isoprene rubber, butadiene rubber, ethylene-propylene rubber, and other rubbery polymers; styrene / butadiene / styrene block copolymers or hydrogenated products thereof, EPDM (ethylene / propylene / diene terpolymers) ), Thermoplastic elastomeric polymers such as styrene / ethylene / butadiene / ethylene copolymers, styrene / isoprene / styrene block copolymers or hydrogenated products
  • a binder may be used individually by 1 type, and may be used in combination of 2 or more type. From the viewpoint of the stability of the positive electrode, it is preferable to use a fluorine-based polymer such as polyvinylidene fluoride (PVdF) or a polytetrafluoroethylene / vinylidene fluoride copolymer.
  • PVdF polyvinylidene fluoride
  • PVdF polytetrafluoroethylene / vinylidene fluoride copolymer
  • the dispersion solvent used for preparing the slurry is not particularly limited, and either an aqueous solvent or an organic solvent may be used.
  • the aqueous solvent include water, a mixed solvent of alcohol and water
  • the organic solvent includes N-methylpyrrolidone (NMP), dimethylformamide, dimethylacetamide, methyl ethyl ketone, cyclohexanone, methyl acetate, methyl acrylate, Diethyltriamine, N, N-dimethylaminopropylamine, tetrahydrofuran (THF), toluene, acetone, diethyl ether, dimethylacetamide, hexamethylphosphalamide, dimethyl sulfoxide, benzene, xylene, quinoline, pyridine, methylnaphthalene, hexane Etc.
  • NMP N-methylpyrrolidone
  • dimethylformamide dimethylacetamide
  • the thickener is not particularly limited, and examples thereof include carboxymethyl cellulose, methyl cellulose, hydroxymethyl cellulose, ethyl cellulose, polyvinyl alcohol, oxidized starch, phosphorylated starch, casein, and salts thereof. These may be used alone or in combination of two or more.
  • the positive electrode mixture layer formed on the current collector is preferably consolidated by a hand press, a roller press or the like in order to improve the packing density of the positive electrode active material.
  • the density of compacted the positive-electrode mixture layer as described above, the input-output characteristics and in view of further improvement of safety, it is preferably 2.4g / cm 3 ⁇ 2.8g / cm 3, 2 More preferably, it is from .45 g / cm 3 to 2.7 g / cm 3 .
  • the material of the positive electrode current collector is not particularly limited. Examples thereof include metal materials such as aluminum, stainless steel, nickel plating, titanium, and tantalum, and carbonaceous materials such as carbon cloth and carbon paper. Of these, metal materials are preferable, and aluminum is more preferable.
  • the shape of the current collector is not particularly limited, and materials processed into various shapes can be used. Examples of the shape when using a metal material include a metal foil, a metal cylinder, a metal coil, a metal plate, a metal thin film, an expanded metal, a punch metal, and a foam metal, and the shape when using a carbonaceous material is a carbon plate, A carbon thin film, a carbon cylinder, etc. are mentioned. Among these, it is preferable to use a metal thin film. The thin film may be formed in a mesh shape as necessary.
  • Negative electrode The negative electrode (negative electrode plate) of the present embodiment is composed of a current collector and a negative electrode mixture layer (negative electrode mixture layer) formed on at least one surface thereof.
  • the negative electrode mixture layer is a layer containing a negative electrode active material, a binder, a thickener used as necessary, and the like.
  • the negative electrode active material preferably contains at least one carbon material selected from the group consisting of graphite and amorphous carbon.
  • Carbon materials are roughly classified into graphite-based carbon materials having a uniform crystal structure and non-graphite-based carbon materials having a disordered crystal structure. From the viewpoint of increasing the capacity of the lithium ion secondary battery, graphite is preferable, and from the viewpoint of safety, amorphous carbon is preferable.
  • Examples of graphite-based carbon materials include natural graphite and artificial graphite.
  • Non-graphite-based carbon materials include amorphous carbon, which includes graphitizable carbon (sometimes called soft carbon) and non-graphitizable carbon (sometimes called hard carbon). are categorized.
  • graphitizable carbon is amorphous carbon that tends to become graphite under temperature conditions of 2000 ° C. to 3000 ° C.
  • non-graphitizable carbon is amorphous that is difficult to become graphite under temperature conditions of 2000 ° C. to 3000 ° C. Carbon.
  • graphitizable carbon is defined as amorphous carbon having a value of the interplanar spacing d002 of less than 0.36 nm in the C-axis direction obtained by the X-ray wide angle diffraction method.
  • Non-graphitizable carbon is defined as amorphous carbon having a surface spacing d002 in the C-axis direction obtained by an X-ray wide-angle diffraction method of 0.36 nm or more.
  • the non-graphitizable carbon has a surface spacing d002 value in the C-axis direction obtained by the X-ray wide angle diffraction method of 0.36 nm to 0.40 nm.
  • the graphitizable carbon has a C-axis direction plane distance d002 value obtained by an X-ray wide angle diffraction method of preferably 0.34 nm or more and less than 0.36 nm, and preferably 0.341 nm to 0.355 nm or less. More preferably, it is 0.342 nm to 0.35 nm or less.
  • Graphite preferably has a C-axis direction plane distance d002 value of 0.33 nm or more and less than 0.34 nm, more preferably 0.335 nm to 0.337 nm or less, obtained by the X-ray wide angle diffraction method.
  • Amorphous carbon can be produced, for example, by heat treating petroleum pitch, polyacene, polyparaphenylene, polyfurfuryl alcohol, or the like. Further, by changing the temperature of the heat treatment, it can be made non-graphitizable carbon or easily graphitized carbon. For example, heat treatment at about 500 ° C. to 800 ° C. is suitable for producing non-graphitizable carbon, and heat treatment at about 800 ° C. to 1000 ° C. is suitable for producing graphitizable carbon.
  • the content ratio is preferably 20% by mass or more, more preferably 50% by mass or more, and still more preferably 70% by mass or more based on the total amount of the negative electrode active material.
  • the average particle size of the negative electrode active material is preferably 2.0 ⁇ m to 50 ⁇ m.
  • the average particle size is 5 ⁇ m or more, the specific surface area can be in an appropriate range, the initial charge / discharge efficiency of the lithium ion secondary battery is excellent, and the particles are in good contact with each other and have excellent input characteristics.
  • the average particle diameter is 30 ⁇ m or less, unevenness is hardly generated on the electrode surface, and short circuit of the battery can be suppressed, and the diffusion distance of Li from the particle surface to the inside becomes relatively short, so that the lithium ion secondary battery Input characteristics tend to improve.
  • the average particle size of the negative electrode active material is more preferably 5 ⁇ m to 30 ⁇ m, and even more preferably 10 ⁇ m to 20 ⁇ m.
  • the average particle diameter of the negative electrode active material is measured with a laser diffraction particle size distribution analyzer (for example, SALD-3000J manufactured by Shimadzu Corporation) by dispersing a sample in purified water containing a surfactant.
  • a laser diffraction particle size distribution analyzer for example, SALD-3000J manufactured by Shimadzu Corporation
  • the value (median diameter (D50)) when the integration from the small diameter side is 50% is used.
  • the negative electrode active material may include a material other than the carbon material.
  • the material other than the carbon material is not particularly limited.
  • a metal oxide such as tin oxide or silicon oxide, a metal composite oxide, a lithium simple substance, a lithium alloy such as a lithium aluminum alloy, or a material capable of forming an alloy with lithium ( Sn, Si, etc.). These materials may be used alone or in combination of two or more.
  • the material of the current collector for the negative electrode is not particularly limited, and examples thereof include metal materials such as copper, nickel, stainless steel, and nickel-plated steel. Among these, copper is preferable from the viewpoint of ease of processing and cost.
  • the shape of the current collector is not particularly limited, and materials processed into various shapes can be used. Specific examples include metal foil, metal cylinder, metal coil, metal plate, metal thin film, expanded metal, punch metal, and foam metal. Among these, a metal thin film is preferable, and a copper foil is more preferable.
  • the method for forming the negative electrode mixture layer is not particularly limited. For example, it can be formed by a dry method or a wet method similarly to the positive electrode mixture layer.
  • the binder contained in the negative electrode mixture layer is not particularly limited. For example, it can select from what was illustrated as a binder used for a positive mix layer.
  • the dispersion solvent used for preparing the slurry is not particularly limited. For example, it can select from what was illustrated as a dispersion
  • the thickener is not particularly limited. For example, it can select from what was illustrated as a thickener used for a positive mix layer.
  • Electrolytic Solution contains an electrolyte and a nonaqueous solvent that dissolves the electrolyte, and may contain other components such as additives as necessary.
  • the electrolyte is not particularly limited as long as it is a lithium salt that can be used as an electrolyte of a non-aqueous electrolyte for a lithium ion secondary battery.
  • the electrolyte include lithium salts such as the following inorganic lithium salts, fluorine-containing organic lithium salts, and oxalatoborate salts. These lithium salts may be used alone or in combination of two or more.
  • inorganic lithium salt LiPF 6, LiBF 4, LiAsF 6, inorganic fluoride salts LiSbF 6 such, LiClO 4, LiBrO 4, perhalogenate of LiIO 4 like, LiA and inorganic chloride salts of LCL 4, and the like.
  • fluorine-containing organic lithium salt examples include perfluoroalkane sulfonates such as LiCF 3 SO 3 ; LiN (CF 3 SO 2 ) 2 , LiN (CF 3 CF 2 SO 2 ) 2 , LiN (CF 3 SO 2 ) (C Perfluoroalkanesulfonylimide salts such as 4 F 9 SO 2 ); LiC (C Perfluoroalkanesulfonylmethide salts such as F 3 SO 2 ) 3 ; Li [PF 5 (CF 2 CF 2 CF 3 )], Li [PF 4 (CF 2 CF 2 CF 3 ) 2 ], Li [PF 3 ( CF 2 CF 2 CF 3 ) 3 ], Li [PF 5 (CF 2 CF 2 CF 2 CF 3 )], Li [PF 4 (CF 2 CF 2 CF 3 )], Li [PF 4 (CF 2 CF 2 CF 2 CF 3 ) 2 ], Li [PF 3 (CF 2 CF 2 CF 3 ) 3
  • oxalatoborate salt examples include lithium bis (oxalato) borate and lithium difluorooxalatoborate.
  • LiPF 6 lithium hexafluorophosphate
  • a preferable combination when two or more lithium salts are used as the electrolyte includes a combination of LiPF 6 and LiBF 4 .
  • the proportion of LiBF 4 in the total of both is preferably 0.01% by mass to 20% by mass, and more preferably 0.1% by mass to 5% by mass.
  • Another preferable combination is a combination of an inorganic fluoride salt and a perfluoroalkanesulfonylimide salt.
  • the proportion of the inorganic fluoride salt in the total of both is preferably 70% by mass to 99% by mass, and more preferably 80% by mass to 98% by mass.
  • the concentration of the electrolyte in the electrolytic solution is not particularly limited. For example, 0.8 mol / L to 1.3 mol / L is preferable, and 0.9 mol / L to 1.2 mol / L is more preferable.
  • concentration of the electrolyte in the electrolytic solution is 0.8 mol / L or more, the electric conductivity of the electrolytic solution tends to be sufficiently secured.
  • concentration of the electrolyte is 1.3 mol / L or less, an increase in the viscosity of the electrolytic solution is suppressed, and a decrease in electrical conductivity tends to be suppressed.
  • the non-aqueous solvent is not particularly limited. Examples include cyclic carbonates, chain carbonates, chain esters, cyclic ethers, chain ethers, and cyclic sulfones, and these may be used alone or in combination of two or more.
  • an alkylene group constituting the cyclic carbonate preferably has 2 to 6 carbon atoms, and more preferably 2 to 4 carbon atoms.
  • Specific examples include ethylene carbonate, propylene carbonate, butylene carbonate, and the like. Of these, ethylene carbonate and propylene carbonate are preferable.
  • the chain carbonate is preferably a dialkyl carbonate, more preferably a dialkyl carbonate in which the two alkyl groups each have 1 to 5 carbon atoms, and even more preferably a dialkyl carbonate in which the two alkyl groups each have 1 to 4 carbon atoms.
  • Dialkyl carbonates include symmetric chain carbonates such as dimethyl carbonate, diethyl carbonate and di-n-propyl carbonate in which two alkyl groups have the same carbon number, and ethyl methyl carbonate and methyl having two different alkyl groups in carbon number. Examples include asymmetric chain carbonates such as -n-propyl carbonate and ethyl-n-propyl carbonate.
  • dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate are preferable.
  • chain esters include methyl acetate, ethyl acetate, propyl acetate, and methyl propionate. Among them, it is preferable to use methyl acetate from the viewpoint of improving the low temperature characteristics.
  • the cyclic ether include tetrahydrofuran, 2-methyltetrahydrofuran, tetrahydropyran and the like.
  • chain ethers include dimethoxyethane and dimethoxymethane.
  • the cyclic sulfone include sulfolane and 3-methylsulfolane.
  • the non-aqueous solvent preferably contains a cyclic carbonate that is a high dielectric constant solvent and a chain carbonate that is a low viscosity solvent.
  • the content is preferably 85% by mass or more and 90% by mass or more based on the total amount of the non-aqueous solvent from the viewpoint of battery characteristics. More preferably, it is more preferably 95% by mass or more.
  • the non-aqueous solvent includes cyclic carbonate and chain carbonate, and cyclic carbonate ( ⁇ ).
  • the volume ratio ( ⁇ / ⁇ ) of the chain carbonate ( ⁇ ) is more preferably 20/80 to 40/60, more preferably 22/78 to 38/62, and 25/75 to 35 / More preferably, it is 65.
  • cyclic carbonate and chain carbonate examples include ethylene carbonate and dimethyl carbonate, ethylene carbonate and diethyl carbonate, ethylene carbonate and ethyl methyl carbonate, ethylene carbonate and dimethyl carbonate and diethyl carbonate, ethylene carbonate and dimethyl carbonate and ethyl Examples thereof include methyl carbonate, ethylene carbonate, diethyl carbonate, and ethyl methyl carbonate, ethylene carbonate, dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate.
  • a combination in which the chain carbonate includes both a symmetric chain carbonate and an asymmetric chain carbonate is preferable.
  • Specific examples include ethylene carbonate, dimethyl carbonate and ethyl methyl carbonate, ethylene carbonate, diethyl carbonate and ethyl methyl carbonate, a combination of ethylene carbonate, dimethyl carbonate, diethyl carbonate and ethyl methyl carbonate.
  • Cycle characteristics and large current discharge characteristics of lithium ion secondary batteries tend to be further improved by combining cyclic carbonate, symmetric chain carbonate, and asymmetric chain carbonate.
  • a combination in which the asymmetric chain carbonate is ethyl methyl carbonate is preferable.
  • a combination in which the chain carbonate is a dialkyl carbonate in which the alkyl group has 1 to 2 carbon atoms is preferable.
  • the nonaqueous solvent may contain an additive from the viewpoint of improving battery characteristics.
  • the additive is not particularly limited.
  • the additive includes at least one selected from the group consisting of nitrogen and sulfur, a heterocyclic compound, a cyclic carboxylic acid ester, a cyclic sulfonic acid ester, a fluorine-containing cyclic carbonate, and other non-inorganic molecules. Examples include compounds having a saturated bond.
  • cyclic sulfonate esters examples include 1,3-propane sultone, 1-methyl-1,3-propane sultone, 3-methyl-1,3-propane sultone, 1,4-butane sultone, 1,3-propene sultone, 1 , 4-butene sultone and the like.
  • 1,3-propane sultone and 1,4-butane sultone are preferable from the viewpoint of reducing the DC resistance.
  • the fluorine-containing cyclic carbonate is not particularly limited, and examples thereof include fluoroethylene carbonate, difluoroethylene carbonate, trifluoroethylene carbonate, tetrafluoroethylene carbonate, and trifluoropropylene carbonate. Among these, fluoroethylene carbonate and the like are particularly preferable from the viewpoint of extending the life of the battery.
  • Other compounds having an unsaturated bond in the molecule include vinylene carbonate, vinyl ethylene carbonate, divinyl ethylene carbonate, methyl vinyl carbonate, ethyl vinyl carbonate, propyl vinyl carbonate, divinyl carbonate, allyl methyl carbonate, allyl ethyl carbonate, allyl propyl.
  • Carbonate compounds such as carbonate, diallyl carbonate, dimethallyl carbonate; vinyl acetate, vinyl propionate, vinyl acrylate, vinyl crotonic acid, vinyl methacrylate, allyl acetate, allyl propionate, methyl acrylate, ethyl acrylate, propyl acrylate , Ester compounds such as methyl methacrylate, ethyl methacrylate, propyl methacrylate; divinyl sulfone, methyl vinyl Sulfone compounds such as sulfone, ethyl vinyl sulfone, propyl vinyl sulfone, diallyl sulfone, allyl methyl sulfone, allyl ethyl sulfone, and allyl propyl sulfone; sulfites such as divinyl sulfite, methyl vinyl sulfite, ethyl vinyl sulfite, and diallyl s
  • vinylene carbonate, dimethacrylic carbonate, vinyl ethylene carbonate, divinyl ethylene carbonate, vinyl acetate, vinyl propionate, vinyl acrylate, divinyl sulfone, vinyl methanesulfonate, and the like are particularly preferable from the viewpoint of extending the life of the battery.
  • additives such as an overcharge inhibitor, a negative electrode film forming agent, a positive electrode protective agent, and a high input / output agent may be used depending on the required function.
  • the separator is disposed between the positive electrode and the negative electrode.
  • the separator includes at least one selected from the group consisting of a first layer containing a polyolefin resin, a polyethylene resin, a polypropylene resin, a polyethylene terephthalate resin, a polyvinyl alcohol resin, a polyacrylonitrile resin, and an aramid resin.
  • a first layer containing a polyolefin resin, a polyethylene resin, a polypropylene resin, a polyethylene terephthalate resin, a polyvinyl alcohol resin, a polyacrylonitrile resin, and an aramid resin.
  • Including a second layer The second layer has a lower air permeability than the first layer, and is disposed closer to the positive electrode than the first layer.
  • the number of first layers and the number of second layers included in the separator are not particularly limited.
  • the separator may include members other than the first layer and the second layer.
  • the thickness of the separator is not particularly limited.
  • the thickness is preferably 10 ⁇ m to 70 ⁇ m, more preferably 12 ⁇ m to 60 ⁇ m, and still more preferably 15 ⁇ m to 50 ⁇ m.
  • the thickness of the separator is 70 ⁇ m or more, the high load discharge characteristics tend to deteriorate.
  • the thickness of the separator is 10 ⁇ m or less, an internal short circuit due to foreign matter or the like tends to occur.
  • the first layer may be made of only a polyolefin resin, or may be made of a polyolefin resin and another resin.
  • the content of the polyolefin resin in the total mass of the first layer is preferably 80% by mass or more, more preferably 90% by mass or more, and further preferably 95% by mass or more.
  • the polyolefin resin contained in the first layer is not particularly limited, and examples thereof include polyethylene and polypropylene. Of these, polyethylene is preferable.
  • the first layer preferably has an air permeability of 20 s to 800 s, more preferably 40 s to 750 s, and still more preferably 60 s to 700 s.
  • the air permeability is a value measured according to the Gurley method (JIS P8117: 2009), and is the time (seconds) for 100 ml of air to pass through a sample area of 645 mm 2 .
  • the thickness of the first layer is not particularly limited.
  • the thickness is preferably 5 ⁇ m to 60 ⁇ m, more preferably 7 ⁇ m to 50 ⁇ m, and still more preferably 10 ⁇ m to 40 ⁇ m.
  • the thickness of the first layer is 60 ⁇ m or more, the high-load discharge characteristics tend to deteriorate.
  • the thickness of the first layer is 5 ⁇ m or less, an internal short circuit due to foreign matter or the like tends to occur.
  • the method for producing the first layer is not particularly limited, and can be selected from known methods.
  • the first layer is a porous sheet.
  • the “porous sheet” means a sheet-like object having pores and air permeability.
  • the second layer is composed of at least one selected from the group consisting of polyethylene resin, polypropylene resin, polyethylene terephthalate resin, polyvinyl alcohol resin, polyacrylonitrile resin and aramid resin, these resins and other resins are used. It may be.
  • the content of at least one selected from the group consisting of polyethylene resin, polypropylene resin, polyethylene terephthalate resin, polyvinyl alcohol resin, polyacrylonitrile resin, and aramid resin in the total mass of the second layer is 80% by mass or more. Is more preferable, 90 mass% or more is more preferable, and 95 mass% or more is further preferable.
  • the resin contained in the second layer is preferably at least one selected from the group consisting of polyethylene resin, polypropylene resin, polyethylene terephthalate resin and aramid resin, and at least selected from the group consisting of polyethylene resin and polypropylene resin.
  • One type is more preferable.
  • the second layer has a lower air permeability than the first layer. If the air permeability of the second layer is smaller than the air permeability of the first layer, when gas is generated in an overcharged state, the gas tends to disperse in the battery container and tends to be superior in safety. .
  • the air permeability of the second layer is preferably 100 s or less, and more preferably 50 s or less.
  • the second layer preferably has a heat shrinkage at 160 ° C. of 2% or less, and more preferably 1% or less.
  • the heat shrinkage rate at 160 ° C. of the second layer is 2% or less, the battery temperature rises in the overcharged state, and even when the first layer is largely heat shrunk, the second layer serves as a separator.
  • the short circuit between the positive electrode and the negative electrode can be suppressed by maintaining the shape.
  • the heat shrinkage rate at 160 ° C. is obtained by subjecting the second layer cut to a size of 70 mm (MD) in length and 58.5 mm (TD) in width to a heat treatment of 15 minutes in an oven at 160 ° C. And obtained from the measured value of the length of the second layer before and after the heat treatment as follows.
  • Thermal shrinkage (%) (length before heat treatment (TD) ⁇ length after heat treatment (TD)) / length before heat treatment ⁇ 100
  • the thickness of the second layer is not particularly limited. The thicker the second layer, the lower the probability of occurrence of a short circuit due to the inclusion of foreign matter or the like. On the other hand, the thinner the second layer, the smaller the distance between the electrodes, and the lower the internal resistance of the battery. Specifically, for example, the thickness is preferably 10 ⁇ m to 50 ⁇ m, more preferably 12 ⁇ m to 40 ⁇ m, and still more preferably 15 ⁇ m to 35 ⁇ m.
  • an inorganic substance may be attached to the second layer by coating, impregnation or the like.
  • inorganic substances include oxides such as alumina and silicon dioxide, nitrides such as aluminum nitride and silicon nitride, and sulfates such as barium sulfate and calcium sulfate.
  • the method for producing the second layer is not particularly limited, and can be selected from known methods.
  • the second layer is a nonwoven fabric.
  • the “nonwoven fabric” means a sheet-like object formed by intertwining fibers without weaving them.
  • the lithium ion secondary battery may have other components other than a positive electrode, a negative electrode, electrolyte solution, and a separator as needed.
  • a cleavage valve may be provided to suppress an increase in pressure inside the battery. By opening the cleavage valve, it is possible to suppress an increase in pressure inside the battery and to improve safety.
  • the cleavage valve can be opened quickly due to the generation of inert gas, and safety can be improved.
  • the shape of the lithium ion secondary battery is not particularly limited, and may be any of a cylindrical shape, a square shape, a laminate type, and the like.
  • the battery capacity of the lithium ion secondary battery is not particularly limited. From the viewpoint of battery control, it is preferably 20 Ah or more.
  • FIG. 1 shows a configuration example of a cylindrical lithium ion secondary battery.
  • an electrode body 5 in which a strip-like positive electrode 2 and a negative electrode 3 are wound in a spiral shape with a separator 4 interposed therebetween is accommodated in a cylindrical battery container 6.
  • a cylindrical battery container 6 Has a structured.
  • the inside of the battery container 6 is filled with an electrolyte solution (not shown).
  • an 18650 type lithium ion secondary battery is widely used as a consumer lithium ion secondary battery.
  • the outer diameter of the 18650 type lithium ion secondary battery is about 18 mm in diameter and about 65 mm in height.
  • the laminate type lithium ion secondary battery can be manufactured, for example, as follows. First, a positive electrode and a negative electrode are cut into squares, and tabs are welded to the respective electrodes to produce positive and negative electrode terminals. A laminate in which the positive electrode, the separator, and the negative electrode are laminated in this order is prepared, and in that state, accommodated in an aluminum laminate pack, and the positive and negative electrode terminals are taken out of the aluminum laminate pack and sealed. Next, the nonaqueous electrolyte is poured into the aluminum laminate pack, and the opening of the aluminum laminate pack is sealed. Thereby, a lithium ion secondary battery is obtained.
  • the capacity ratio between the negative electrode and the positive electrode is preferably 1 or more and less than 1.4 from the viewpoint of safety and energy density, and is 1.05 to 1.25. Is more preferable.
  • the negative electrode capacity means [negative electrode discharge capacity]
  • the positive electrode capacity means [positive charge capacity of positive electrode minus negative electrode or positive electrode, whichever is greater].
  • discharge capacity of negative electrode is defined as a value calculated by a charge / discharge device when lithium ions inserted into the negative electrode active material are desorbed.
  • the “initial charge capacity of the positive electrode” is defined as that calculated by the charge / discharge device when lithium ions are desorbed from the positive electrode active material.
  • the capacity ratio between the negative electrode and the positive electrode can be calculated from, for example, “discharge capacity of lithium ion secondary battery / discharge capacity of negative electrode”.
  • the discharge capacity of the lithium ion secondary battery is, for example, 0.4 V, 0.1 to 0.5 C, and a constant current and constant voltage (CCCV) charge with an end time of 2 hours to 5 hours, and then is set to 0. It can be measured under conditions when a constant current (CC) is discharged to 2.7 V at 1 to 0.5 C.
  • the discharge capacity of the negative electrode is obtained by cutting a negative electrode whose discharge capacity of a lithium ion secondary battery is measured into a predetermined area, using lithium metal as a counter electrode, and producing a single electrode cell through a separator impregnated with an electrolyte, Discharge capacity per predetermined area under the conditions of constant current (CCCV) charge at 0V, 0.1C, and final current 0.01C, and then constant current (CC) discharge to 1.5V at 0.1C Can be calculated by converting the total area when this is used as the negative electrode of a lithium ion secondary battery.
  • CCCV constant current
  • CC constant current
  • C means “current value (A) / battery discharge capacity (Ah)”.
  • the positive electrode was produced as follows.
  • As the positive electrode active material a layered type lithium / nickel / manganese / cobalt composite oxide (BET specific surface area of 0.4 m 2 / g, average particle diameter (D50) of 6.5 ⁇ m) was used.
  • acetylene black manufactured by Denki Kagaku Kogyo Co., Ltd., trade name: HS-100, average particle size 48 nm (catalog value)
  • NMP N-methyl-2 of polyvinylidene fluoride
  • NMP N-methyl-2-pyrrolidone
  • a dispersion solvent was added to the above mixture and kneaded to prepare a slurry.
  • This slurry was applied to both surfaces of a 20 ⁇ m thick aluminum foil as a positive electrode current collector so that the thickness was substantially uniform and uniform.
  • a drying treatment was performed.
  • a notch was formed in the uncoated portion of the aluminum foil, and the remainder of the notch was used as a lead piece.
  • the width of the lead piece was 10 mm, and the interval between adjacent lead pieces was 20 mm.
  • the density of the positive electrode mixture was 2.5 g / cm 3 . This was cut again to produce a positive electrode having a width of 195 mm.
  • the negative electrode was produced as follows.
  • graphitizable carbon (d002 is 0.35 nm, average particle diameter (D50) is 17 ⁇ m) was used.
  • NMP N-methyl-2-pyrrolidone
  • NMP N-methyl-2-pyrrolidone
  • a drying treatment was performed. Next, a notch was made in the uncoated part of the rolled copper foil, and the remaining part of the notch was used as a lead piece. The width of the lead piece was 10 mm, and the interval between adjacent lead pieces was 20 mm. Then, it compacted with the press to the predetermined density. The negative electrode mixture density was 1.15 g / cm 3 . This was cut again to produce a negative electrode having a width of 196 mm.
  • ethylene carbonate (EC), dimethyl carbonate (DMC) and ethyl methyl carbonate (EMC) are mixed so that the volume ratio (EC: DMC: EMC) is 30:40:30, and a mixed solution.
  • LiPF 6 lithium hexafluorophosphate
  • Example 1 a positive electrode produced as described above, one nonwoven fabric made of polyethylene and polypropylene fibers having a thickness of 18 ⁇ m, and a polyethylene microporous film (hereinafter also referred to as a PE porous sheet) 1 having a thickness of 30 ⁇ m.
  • the sheet and the negative electrode prepared above were superposed in this order and wound from the end to prepare a roll-shaped electrode body.
  • the lead piece of the positive electrode and the lead piece of the negative electrode were arranged so as to be located on the opposite end surfaces of the electrode body, respectively.
  • the lengths of the positive electrode, the negative electrode, and the separator were adjusted so that the diameter of the electrode body was 65 ⁇ 0.1 mm.
  • the air permeability of a nonwoven fabric made of polyethylene and polypropylene fibers having a thickness of 18 ⁇ m was 1 s or less.
  • Example 2 the positive electrode prepared above, one nonwoven fabric made of polyethylene and polypropylene fibers having a thickness of 18 ⁇ m, one PE porous sheet having a thickness of 20 ⁇ m, and the negative electrode prepared above were used.
  • a roll-shaped electrode body was produced in the same manner as in Example 1 except that they were superposed in order.
  • Example 3 the positive electrode prepared above, one nonwoven fabric made of polyethylene and polypropylene fibers having a thickness of 21 ⁇ m, one PE porous sheet having a thickness of 20 ⁇ m, and the negative electrode prepared above were used.
  • a roll-shaped electrode body was produced in the same manner as in Example 1 except that they were superposed in order.
  • Comparative Example 1 a roll-shaped electrode was prepared in the same manner as in Example 1 except that the positive electrode prepared above, one PE porous sheet having a thickness of 30 ⁇ m, and the negative electrode prepared above were superposed in this order. The body was made.
  • a roll-shaped electrode was prepared in the same manner as in Example 1 except that the positive electrode prepared above, one PE porous sheet having a thickness of 50 ⁇ m, and the negative electrode prepared above were superposed in this order. The body was made.
  • Comparative Example 3 the positive electrode produced above, one PE porous sheet having a thickness of 30 ⁇ m, one nonwoven fabric made of polyethylene and polypropylene fibers having a thickness of 18 ⁇ m, and the negative electrode produced above were used.
  • a roll-shaped electrode body was produced in the same manner as in Example 1 except that they were superposed in order.
  • a lithium ion secondary battery having a structure as shown in FIG. 2 was produced using the electrode body and the electrolytic solution produced above.
  • the lead pieces 9 led out from the positive electrode were deformed, and all of them were gathered near the bottom of the flange 7 on the positive electrode side and brought into contact with each other.
  • the flange portion 7 on the positive electrode side is integrally formed so as to protrude from the periphery of the pole column (positive electrode external terminal 1) substantially on the extension line of the axis of the electrode body 6, and has a bottom portion and a side portion. Thereafter, the lead piece 9 was connected and fixed to the bottom of the flange 7 by ultrasonic welding. Similarly, the lead piece 9 led out from the negative electrode and the bottom of the flange 7 on the negative electrode side were connected and fixed.
  • the negative electrode side flange portion 7 is integrally formed so as to project from the periphery of the pole column (negative electrode external terminal 1 ′) substantially on the extension line of the axis of the electrode body 6, and has a bottom portion and a side portion.
  • an insulating coating 8 was formed by covering the side of the flange 7 on the positive electrode external terminal 1 side and the side of the flange 7 of the negative electrode external terminal 1 ′. Similarly, an insulating coating 8 was formed on the outer periphery of the electrode body 6. Specifically, the adhesive tape is stretched from the side of the flange 7 on the positive electrode external terminal 1 side to the outer peripheral surface of the electrode body 6, and further from the outer peripheral surface of the electrode body 6 to the negative electrode external terminal 1 ′ side. Insulating coating 8 was formed by winding several times over the side of 7.
  • the adhesive tape which apply
  • the thickness of the insulating coating 8 (the number of windings of the adhesive tape) is adjusted so that the maximum diameter portion of the electrode body 6 is slightly smaller than the inner diameter of the stainless steel battery container 5, and the electrode body 6 is placed in the battery container 5. Inserted. A battery container 5 having an outer diameter of 67 mm and an inner diameter of 66 mm was used.
  • the ceramic washer 3 ′ was fitted into a pole column whose tip constitutes the positive electrode external terminal 1 and a pole column whose tip constitutes the negative electrode external terminal 1 ′.
  • a ceramic washer having a thickness of 2 mm, an inner diameter of 16 mm, and an outer diameter of 25 mm made of alumina and in contact with the back surface of the battery lid 4 was used.
  • the positive external terminal 1 is passed through the ceramic washer 3, and with the other ceramic washer 3 placed on the other battery lid 4, the negative external terminal 1 'was passed through another ceramic washer 3.
  • a flat plate having a thickness of 2 mm, an inner diameter of 16 mm, and an outer diameter of 28 mm was used.
  • the battery lid 4 was provided with a cleavage valve 10 that cleaves in response to an increase in the internal pressure of the battery.
  • the cleavage pressure of the cleavage valve 10 was 13 kg / cm 2 to 18 kg / cm 2 .
  • the metal washer 11 was fitted into the positive external terminal 1 and the negative external terminal 1 '. Thereby, the metal washer 11 was arranged on the ceramic washer 3. As the metal washer 11, a material made of a material smoother than the bottom surface of the nut 2 was used.
  • a metal nut 2 is screwed to the positive electrode external terminal 1 and the negative electrode external terminal 1 ′, and the battery lid 4 is connected to the flange portion 7 and the nut 2 via the ceramic washer 3, the metal washer 11, and the ceramic washer 3 ′. And fixed by tightening between.
  • the tightening torque value at this time was 70 kgf ⁇ cm.
  • the metal washer 11 was not rotated until the tightening operation was completed.
  • the power generation element inside the battery container 5 is shielded from the outside air by the compression of the rubber (EPDM) O-ring 12 interposed between the back surface of the battery lid 4 and the flange 7.
  • the initialization charge / discharge cycle was performed in a temperature environment of 25 ° C.
  • the current value was 20 A for both charging and discharging.
  • Charging was constant current constant voltage (CCCV) charging with 4.1 V as the upper limit voltage, and the termination condition was 3 hours.
  • the discharge was a constant current (CC) discharge with 2.7 V as the end condition. Further, a pause of 30 minutes was put between charge and discharge. This was carried out for 3 cycles.
  • Comparative Example 1 and Comparative Example 2 using only one PE porous sheet were excellent in high-load discharge characteristics, but resulted in rupture, ignition or smoke in an overcharged state.
  • Comparative Example 3 in which the porous sheet was disposed on the positive electrode side and the non-woven fabric was disposed on the negative electrode side resulted in inferior high-load discharge characteristics although no rupture, ignition or smoke occurred in the overcharged state.
  • Comparative Example 3 The reason why the high-load discharge characteristics of Comparative Example 3 are particularly inferior is not clear, but, for example, if a viscosity distribution occurs due to the concentration distribution of the electrolyte during charge and discharge, it is easily affected by the air permeability of the separator. It is possible to become. Nonwoven fabrics have a lower air permeability than porous sheets, so even electrolytes with high viscosity are less affected, but PE (polyethylene) has a higher air permeability and is strongly affected by it. It seems that this has led to a decrease in the capacity ratio.
  • PE polyethylene
  • Comparative Example 1 and Comparative Example 2 The reason why the safety evaluation result in the overcharged state is inferior in Comparative Example 1 and Comparative Example 2 is considered as follows. It is known that in an overcharged state, the pressure inside the battery can increases due to decomposition and gasification of the electrolyte. In the case of a non-woven fabric, as described above, since the air permeability is low, the gas escape is good and the generated gas is well dispersed in the battery can, but the PE porous sheet is generated because the air permeability is high. It is considered that the positive electrode and the negative electrode were strongly pressed by the pressure of the gas and the short circuit was easily caused.
  • the lithium ion secondary battery of the present embodiment is excellent in high-load discharge characteristics and safety in an overcharged state.

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Abstract

La présente invention aborde le problème de la fourniture d'une batterie secondaire au lithium-ion ayant d'excellentes caractéristiques de décharge à charge élevée et une excellente sécurité en cas de surcharge. La présente invention porte sur une batterie secondaire au lithium-ion qui comprend une électrode positive, une électrode négative, un séparateur disposé entre l'électrode positive et l'électrode négative, et un électrolyte non aqueux. Le séparateur comporte : une première couche contenant une résine de polyoléfine ; et une seconde couche contenant au moins une résine choisie dans le groupe constitué par des résines de polyoléfine, des résines de polypropylène, des résines de téréphtalate de polyéthylène, des résines d'alcool polyvinylique, des résines de polyacrylonitrile, et des résines d'aramide, ladite seconde couche ayant une perméabilité à l'air inférieure à celle de la première couche, et étant disposée plus près de l'électrode positive que la première couche.
PCT/JP2016/071188 2015-07-21 2016-07-19 Batterie secondaire au lithium-ion WO2017014222A1 (fr)

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JP2013511124A (ja) * 2009-11-16 2013-03-28 コカン カンパニー リミテッド リチウム二次電池用セパレータ及びこれを含むリチウム二次電池
JP2013191345A (ja) * 2012-03-13 2013-09-26 Hitachi Maxell Ltd リチウム二次電池およびその製造方法
JP2013536981A (ja) * 2010-09-06 2013-09-26 エルジー・ケム・リミテッド セパレータ、その製造方法、及びそれを備える電気化学素子
JP2014035926A (ja) * 2012-08-09 2014-02-24 Sanyo Electric Co Ltd 非水電解質二次電池
JP2014116101A (ja) * 2012-12-06 2014-06-26 Sanyo Electric Co Ltd 非水電解液二次電池
JP2014203649A (ja) * 2013-04-04 2014-10-27 Ｆｄｋトワイセル株式会社 セパレータ及びこのセパレータを用いたアルカリ蓄電池

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5902696A (en) * 1997-06-02 1999-05-11 Wilson Greatbatch Ltd. Separator for nonaqueous electrochemical cells
JP2006261093A (ja) * 2005-02-10 2006-09-28 Maxell Hokuriku Seiki Kk 非水二次電池
JP2010080284A (ja) * 2008-09-26 2010-04-08 Panasonic Corp 偏平形非水電解液二次電池
JP2011070789A (ja) * 2008-09-26 2011-04-07 Sanyo Electric Co Ltd 非水電解質二次電池
JP2013511124A (ja) * 2009-11-16 2013-03-28 コカン カンパニー リミテッド リチウム二次電池用セパレータ及びこれを含むリチウム二次電池
JP2011198532A (ja) * 2010-03-18 2011-10-06 Hitachi Maxell Ltd リチウムイオン二次電池
JP2013536981A (ja) * 2010-09-06 2013-09-26 エルジー・ケム・リミテッド セパレータ、その製造方法、及びそれを備える電気化学素子
JP2013191345A (ja) * 2012-03-13 2013-09-26 Hitachi Maxell Ltd リチウム二次電池およびその製造方法
JP2014035926A (ja) * 2012-08-09 2014-02-24 Sanyo Electric Co Ltd 非水電解質二次電池
JP2014116101A (ja) * 2012-12-06 2014-06-26 Sanyo Electric Co Ltd 非水電解液二次電池
JP2014203649A (ja) * 2013-04-04 2014-10-27 Ｆｄｋトワイセル株式会社 セパレータ及びこのセパレータを用いたアルカリ蓄電池

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