WO2016021513A1 - リチウムイオン二次電池 - Google Patents

リチウムイオン二次電池 Download PDF

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Publication number
WO2016021513A1
WO2016021513A1 PCT/JP2015/071860 JP2015071860W WO2016021513A1 WO 2016021513 A1 WO2016021513 A1 WO 2016021513A1 JP 2015071860 W JP2015071860 W JP 2015071860W WO 2016021513 A1 WO2016021513 A1 WO 2016021513A1
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WIPO (PCT)
Prior art keywords
container
resin
lithium ion
ion secondary
secondary battery
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Application number
PCT/JP2015/071860
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English (en)
French (fr)
Japanese (ja)
Inventor
秀之 小川
信之 小川
愛知　且英
正嗣 青谷
英介 羽場
洋生 西山
智季 池田
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日立化成株式会社
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Priority to JP2016540199A priority Critical patent/JPWO2016021513A1/ja
Publication of WO2016021513A1 publication Critical patent/WO2016021513A1/ja

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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
    • 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
    • H01M10/056—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
    • H01M10/0587—Construction or manufacture of accumulators having only wound construction elements, i.e. wound positive electrodes, wound negative electrodes and wound separators
    • 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.
  • Lithium ion secondary batteries are widely used as power sources for portable electronic devices and electric vehicles because of their high energy density.
  • a winding electrode body is accommodated in a cylindrical battery can.
  • the take-up electrode body is configured by sandwiching a microporous separator between a positive electrode and a negative electrode and winding them in a spiral shape, and the separator is impregnated with a combustible electrolyte.
  • Lithium ion secondary batteries are required to further improve safety in order to further increase energy density and size in the future.
  • a lithium ion secondary battery that improves flame retardancy by adding a phosphate ester (trimethyl phosphate, triethyl phosphate, etc.) to the electrolyte has been proposed.
  • a phosphate ester trimethyl phosphate, triethyl phosphate, etc.
  • a lithium ion secondary battery has been proposed that incorporates a structure containing an endothermic substance (such as Na-type BC fire extinguisher) into the battery, so that the endothermic substance is released during thermal runaway and prevents ignition due to battery temperature rise.
  • an endothermic substance such as Na-type BC fire extinguisher
  • a lithium ion secondary battery can be said to be a lithium ion secondary battery with high safety if it does not ignite even if gas derived from an electrolyte is ejected, or if combustion can be suppressed early even if ignited.
  • the present invention has been made in view of the above circumstances, and an object of the present invention is to provide a lithium ion secondary battery in which deterioration of battery characteristics is suppressed and safety is excellent.
  • a lithium ion secondary comprising a structure having a container made of a metal-containing material and at least one selected from the group consisting of bromoform and carbon tetrabromide disposed inside the container. battery.
  • a container made of the metal-containing material is used as a first container, and a polypropylene resin, a polyethylene terephthalate resin, a polyamide resin, a polyimide resin, and ethylene-vinyl alcohol are arranged inside the first container.
  • a battery container, an electrode winding group obtained by winding the positive electrode, the negative electrode, and the separator, and an electrolytic solution, and the structure is disposed in a gap in the center of the electrode winding group.
  • ⁇ 4> The lithium ion secondary battery according to ⁇ 3>, wherein the electrolytic solution includes a cyclic carbonate and a chain carbonate.
  • ⁇ 5> The lithium ion secondary battery according to any one of ⁇ 1> to ⁇ 4>, wherein the metal includes aluminum.
  • ⁇ 6> At least one selected from the group consisting of bromoform and carbon tetrabromide is released from the container at a temperature of 80 ° C. or higher, according to any one of ⁇ 1> to ⁇ 5> Lithium ion secondary battery.
  • the present invention it is possible to provide a lithium ion secondary battery in which deterioration of battery characteristics is suppressed and safety is excellent.
  • a numerical range indicated using “to” indicates a range including the numerical values described before and after “to” as the minimum value and the maximum value, respectively.
  • the content of a certain component means the total amount of the plurality of substances when there are a plurality of substances corresponding to the component, unless otherwise specified.
  • the term “layer” includes not only the configuration of the shape formed on the entire surface when observed as a plan view, but also the configuration of the shape formed in part.
  • the term “stacked” indicates that the layers are stacked, and two or more layers may be bonded, or two or more layers may be detachable.
  • the lithium ion secondary battery of the present disclosure includes a container made of a metal-containing material and at least one selected from the group consisting of bromoform and carbon tetrabromide disposed inside the container (hereinafter referred to as a specific flame retardant). And a structure having the following. By setting it as such a structure, the lithium ion secondary battery of this indication is suppressed in the fall of a battery characteristic, and is excellent in safety
  • the flame retardant effect per volume of the compound containing phosphorus or bromine (which is an effect of suppressing combustion when ignited by the ejected gas, and may be referred to as self-extinguishing in the following) is high. From such a viewpoint, a compound having a large specific gravity is preferable. Considering the specific gravity and the radical trapping effect, it can be assumed that a compound containing bromine is effective.
  • bromoform or carbon tetrabromide is particularly excellent in self-extinguishing properties.
  • the reason why bromoform or carbon tetrabromide is excellent in self-extinguishing properties is considered as follows.
  • the electrolyte solution of a lithium ion secondary battery generally contains a mixed solvent of a cyclic carbonate and a chain carbonate, which will be described later.
  • the boiling point of the cyclic carbonate or chain carbonate is about 90 ° C. to 261 ° C.
  • the boiling point of bromoform is 149 ° C.
  • bromoform or carbon tetrabromide is disposed inside a container made of a material containing a metal.
  • bromides having no boiling point below 261 ° C. such as decabromodiphenyl ether and 1,2-bis (2,3,4,5,6-pentabromophenyl) ethane are difficult to vaporize and thus There is a tendency to be inferior in fire extinguishing properties.
  • bromides with a boiling point of 110 ° C. or lower such as bromotrichloromethane and dibromomethane, volatilize earlier than the electrolyte at the early stage of combustion, and therefore suppress the combustion of vaporized components derived from the electrolyte that is ejected thereafter. It becomes difficult.
  • the electrolyte containing the solvent described later exhibits high self-extinguishing properties when the boiling point of bromoform or carbon tetrabromide is about 150 ° C to 200 ° C. It is speculated that this is the main factor.
  • a positive electrode a negative electrode
  • an electrolytic solution a separator, and other components
  • the present invention is not limited to the following description.
  • the lithium ion secondary battery of 1st Embodiment is provided with the structure which has a container which consists of a material containing a metal, and the specific flame retardant arrange
  • the form of the structure is not particularly limited, and can be selected according to the use of the battery, the position of the structure within the battery, and the like. Examples of the structure include a container shape, a bag shape, a cylindrical shape, and a capsule shape.
  • the structure is configured such that the specific flame retardant is released from the container at a temperature higher than the normal use temperature of the battery.
  • the structure is preferably configured such that the specific flame retardant is released from the container at a temperature of 80 ° C. or higher.
  • the metal contained in the material including the metal constituting the container examples include copper, aluminum, gold, brass, nickel, titanium, copper alloy, stainless steel, tin, and high nickel alloy. From the viewpoint of toughness and handleability, the metal is preferably aluminum. Only one type of metal may be used or two or more types of metals may be used.
  • the material containing metal may be processed into a metal plate, a metal foil, a metal film, or the like according to the shape of the container.
  • the metal-containing material is a metal foil
  • the thickness is preferably 2 ⁇ m to 300 ⁇ m, more preferably 3 ⁇ m to 100 ⁇ m, and still more preferably 5 ⁇ m to 50 ⁇ m.
  • the material constituting the container may be only metal or a combination of metal and other materials.
  • Examples of the combination of metal and other materials include a laminate of a metal foil and a resin film, a metal film deposited on the surface of the resin film, and the like.
  • the resin includes polyethylene resin, polypropylene resin, polyethylene terephthalate resin, polyamide resin, ethylene-vinyl alcohol copolymer resin, ethylene-vinyl acetate copolymer resin, acrylonitrile- Examples include butadiene copolymer resins, cellophane resins, vinylon resins, vinylidene chloride resins, epoxy resins, polyimide resins, acrylic resins, and the like. Two or more of these resins may be used in combination in the container. For example, a three-layer structure of polyethylene film / metal foil / polyethylene terephthalate film may be used. As the polyethylene resin, either low density or high density can be used.
  • the softening point of the resin contained in the material constituting the container is preferably 80 ° C. to 300 ° C. When the softening point of the resin is within this range, the container is more easily destroyed when the lithium ion secondary battery is placed at a high temperature of 80 ° C. or higher, and the specific flame retardant is more easily released from the inside of the container. .
  • the resin having a softening point of 80 ° C. to 300 ° C. include polyethylene resin, polypropylene resin, polyethylene terephthalate resin, and polyamide resin.
  • the softening point in the present disclosure is a temperature at which a substance starts to soften and deform when the substance is heated. The softening point can be calculated from the peak temperature converted into a differential curve after measuring the change in the specific heat capacity of the polymer in the inert gas as a temperature function using a heating differential scanning calorimeter.
  • a resin having adhesive ability may be used for the preparation of the container.
  • the resin having adhesive ability include acrylic resin, urethane resin, epoxy resin, acrylate resin, chloroprene rubber, silicone resin, polyimide resin, polyvinyl acetate resin, polyvinyl alcohol resin, and resorcinol resin.
  • acrylic resin, urethane resin, epoxy resin, acrylate resin, chloroprene rubber, silicone resin, polyimide resin, polyvinyl acetate resin, polyvinyl alcohol resin, and resorcinol resin are preferable from the viewpoint of adhesive strength with metal.
  • the resin having adhesive ability may be a tape-like resin applied to a substrate.
  • the specific flame retardant is prevented from being mixed in the electrolyte solution in the normal use temperature range of the battery, and the deterioration of the battery characteristics is suppressed.
  • the specific flame retardant can be released from the container into the electrolytic solution.
  • the material of the container includes a resin film or a resin having adhesive ability
  • the specific flame retardant can be released from the container into the electrolytic solution by melting the resin due to a temperature rise. it can.
  • the specific flame retardant expands due to heat, and the container bursts as the internal pressure of the container rises, releasing the specific flame retardant from the container into the electrolyte.
  • Select the type, thickness, shape, etc. arrange another substance inside the container together with the specific flame retardant, adjust the boiling point, arrange the foaming agent to increase the rate of increase of internal pressure due to temperature rise Is preferable.
  • the position of the structure inside the lithium ion secondary battery is not particularly limited. In order not to impair the energy density of the battery, it is preferable to make effective use of voids (spaces in which members other than the electrolyte, such as power generation elements and terminals, do not exist) in the battery.
  • voids spaces in which members other than the electrolyte, such as power generation elements and terminals, do not exist
  • the void inside the battery in the case of a battery in which the electrode group is a wound type, there is a void at the center of the electrode winding group formed by winding the positive electrode, the negative electrode, and the separator.
  • the amount of the specific flame retardant disposed inside the container is preferably 3% by mass or more with respect to the total amount of the electrolytic solution from the viewpoint of ensuring sufficient flame retardancy, and is 5% by mass or more. More preferred is 10% by mass or more.
  • the upper limit of the amount of the specific flame retardant is not particularly limited, but considering the size of the space occupied by the structure inside the battery, it is preferably 40% by mass or less, and 30% by mass or less with respect to the total amount of the electrolytic solution. Is more preferable, and it is still more preferable that it is 20 mass% or less.
  • the amount of the specific flame retardant is X mass% with respect to the total amount of the electrolytic solution” is expressed by an electrolytic solution: a specific flame retardant when the total mass of the electrolytic solution and the specific flame retardant is 100. It means that the mass ratio is (100-X): X.
  • Substances other than the specific flame retardant may be disposed inside the container.
  • examples of such substances include substances having a flame retardant effect other than the specific flame retardant, foaming agents, and the like.
  • the total mass of the specified flame retardant and the substances other than the specified flame retardant is the amount of the electrolyte, considering the size of the space occupied by the structure inside the battery. It is preferable that it is 40 mass% or less with respect to the whole quantity, It is more preferable that it is 30 mass% or less, It is still more preferable that it is 20 mass% or less.
  • the total mass of substances other than the specific flame retardant and the specific flame retardant is X mass% with respect to the total amount of the electrolytic solution” means that the total mass of substances other than the electrolytic solution, the specific flame retardant and the specific flame retardant is 100. Means that the mass ratio represented by the electrolyte solution: the specific flame retardant and the substance other than the specific flame retardant is (100-X): X.
  • a lithium ion secondary battery of the second embodiment is arranged inside a first container and a first container made of a material containing a metal.
  • a structure having a second container made of a specific resin material described later and a specific flame retardant disposed inside the second container is provided.
  • the specific flame retardant can be prevented from leaking into the battery even when used under severe temperature conditions, and at a high temperature (for example, 80 Since the specific flame retardant is released into the battery, safety can be ensured.
  • the form of the structure is not particularly limited, and can be selected according to the use of the battery, the position of the structure within the battery, and the like.
  • Examples of the structure include a container shape, a bag shape, a cylindrical shape, and a capsule shape.
  • the structure is configured such that the specific flame retardant is released from the structure at a temperature higher than the normal use temperature of the battery.
  • the structure is preferably configured such that the specific flame retardant is released from the structure at a temperature of 80 ° C. or higher.
  • Examples of the metal contained in the material containing the metal constituting the first container include copper, aluminum, gold, brass, nickel, titanium, copper alloy, stainless steel, tin, and high nickel alloy. From the viewpoint of toughness and handleability, the metal is preferably aluminum. Only one type of metal may be used or two or more types of metals may be used.
  • the material containing metal may be processed into a metal plate, a metal foil, a metal film, or the like depending on the form of the first container.
  • the metal-containing material is a metal foil
  • the thickness is preferably 2 ⁇ m to 300 ⁇ m, more preferably 3 ⁇ m to 100 ⁇ m, and still more preferably 5 ⁇ m to 50 ⁇ m.
  • the material constituting the first container may be only metal or a combination of metal and other materials.
  • Examples of the combination of metal and other materials include a laminate of a metal foil and a resin film, and a metal film deposited on the surface of the resin film.
  • the resin includes polyethylene resin, polypropylene resin, polyethylene terephthalate resin, polyamide resin, ethylene-vinyl alcohol copolymer resin, ethylene-vinyl acetate copolymer resin.
  • Two or more of these resins may be used in combination in the first container.
  • a three-layer structure of polyethylene film / metal foil / polyethylene terephthalate film or polyethylene film / metal foil / polypropylene film may be used.
  • As the polyethylene resin either low density or high density can be used.
  • the softening point of the resin contained in the material constituting the first container is preferably 80 ° C. to 300 ° C. When the softening point of the resin is within this range, the first container is more easily destroyed when the lithium ion secondary battery is placed in a high temperature state of 80 ° C. or more, and the specific flame retardant is the first container. Easier to be released from inside.
  • the resin having a softening point of 80 ° C. to 300 ° C. include polyethylene resin, polypropylene resin, polyethylene terephthalate resin, and polyamide resin.
  • the softening point in the present disclosure is a temperature at which a substance starts to soften and deform when the substance is heated. The softening point can be calculated from the peak temperature converted into a differential curve after measuring the change in the specific heat capacity of the polymer in the inert gas as a temperature function using a heating differential scanning calorimeter.
  • a resin having an adhesive ability may be used for the production of the first container.
  • the resin having adhesive ability include acrylic resin, urethane resin, epoxy resin, acrylate resin, chloroprene rubber, silicone resin, polyimide resin, polyvinyl acetate resin, polyvinyl alcohol resin, and resorcinol resin.
  • an epoxy resin, an acrylate resin, etc. are preferable from a viewpoint of the adhesive force with a metal.
  • the resin having adhesive ability may be a tape-like resin applied to a substrate.
  • Specific resin materials constituting the second container are polypropylene resin, polyethylene terephthalate resin, polyamide resin, polyimide resin, ethylene-vinyl alcohol copolymer resin, ethylene-vinyl acetate copolymer resin, acrylonitrile-butadiene copolymer. It is at least one selected from the group consisting of resins, cellophane resins, vinylon resins, vinylidene chloride resins, epoxy resins, and acrylic resins. Two or more of the specific resin materials may be used in combination in the second container.
  • the flame retardant release temperature can be adjusted to 80 ° C. to 300 ° C.
  • the specific flame retardant is hardly released at a temperature lower than 80 ° C., which is a normal use temperature range of the lithium ion secondary battery, and is included in the material constituting the first container. It can prevent metal corrosion.
  • the flame retardant release temperature is 80 ° C. to 300 ° C.
  • the specific flame retardant is released from the inside of the second container when the lithium ion secondary battery is placed in a high temperature state of 80 ° C. or higher. Cheap.
  • the flame retardant release temperature in the present disclosure refers to the second container containing 1 g of the specific flame retardant (the ratio of the specific flame retardant is 30% by mass or more of the total weight of the second container) for 1 hour. This is the temperature at which the weight loss rate becomes 1% or more of the total weight after standing.
  • the specific resin materials it is more preferable to use a polyethylene terephthalate resin or a polypropylene resin from the viewpoint of shielding properties of the specific flame retardant.
  • the metal contained in the material constituting the first container can be prevented from corroding by the specific flame retardant or its decomposition product in the normal use temperature range of the battery. . For this reason, it is suppressed that a specific flame retardant mixes in electrolyte solution, and the fall of a battery characteristic is suppressed.
  • the specific flame retardant can be released from the second container, and then the specific flame retardant can be released from the first container into the electrolytic solution.
  • the resin constituting the second container is softened or melted by the temperature rise, and the specific flame retardant is released.
  • the material constituting the first container includes a resin film or a resin having an adhesive ability
  • the resin is softened or melted by the temperature rise, so that the specific flame retardant is removed from the first container in the electrolytic solution. Can be released.
  • the specific flame retardant expands due to heat, and the internal pressure of the first container rises, causing the first container to burst,
  • the specific flame retardant can be released from the structure into the electrolyte.
  • the specific flame retardant is released from the first container into the electrolytic solution by melting or rupturing the first container, the first container is within a range of 80 ° C. to 300 ° C. depending on the use of the battery. Select the type, thickness, shape, etc.
  • the specific resin material constituting the second container is polyethylene terephthalate. It is preferable to use a resin or a polypropylene resin. In this case, it is preferable to adjust the flame retardant release temperature to 100 ° C. to 300 ° C.
  • the position of the structure inside the lithium ion secondary battery is not particularly limited. In order not to impair the energy density of the battery, it is preferable to make effective use of voids (spaces in which members other than the electrolyte, such as power generation elements and terminals, do not exist) in the battery.
  • the void portion inside the battery includes a void portion at the center of the electrode winding group formed by winding the positive electrode, the negative electrode, and the separator.
  • the structure is preferably disposed on the outer periphery of the electrode winding group (for example, the gap between the electrode winding group and the battery container).
  • the amount of the specific flame retardant disposed inside the second container is preferably 3% by mass or more with respect to the total amount of the electrolytic solution from the viewpoint of ensuring sufficient flame retardancy. More preferably, it is more preferably 10% by mass or more.
  • the upper limit of the amount of the specific flame retardant is not particularly limited, but considering the size of the space occupied by the structure inside the battery, it is preferably 40% by mass or less, and 30% by mass or less with respect to the total amount of the electrolytic solution. Is more preferable, and it is still more preferable that it is 20 mass% or less.
  • the amount of the specific flame retardant is X mass% with respect to the total amount of the electrolytic solution” is expressed by an electrolytic solution: a specific flame retardant when the total mass of the electrolytic solution and the specific flame retardant is 100. It means that the mass ratio is (100-X): X.
  • Substances other than the specific flame retardant may be disposed inside the second container.
  • examples of such substances include substances having a flame retardant effect other than the specific flame retardant, foaming agents, and the like.
  • the total mass of the specified flame retardant and the substances other than the specified flame retardant is the amount of the electrolyte, considering the size of the space occupied by the structure inside the battery. It is preferable that it is 40 mass% or less with respect to the whole quantity, It is more preferable that it is 30 mass% or less, It is still more preferable that it is 20 mass% or less.
  • the total mass of substances other than the specific flame retardant and the specific flame retardant is X mass% with respect to the total amount of the electrolytic solution” means that the total mass of substances other than the electrolytic solution, the specific flame retardant, and the specific flame retardant is 100.
  • the structure 1 according to the present embodiment includes a first container 5 made of a metal-containing material, and a second resin made of a specific resin material disposed inside the first container 5. And the specific flame retardant 10 disposed inside the second container 9.
  • the first container 5 is composed of a film having a three-layer structure in which a resin surface layer 6, a metal layer 7, and a resin adhesive layer 8 are laminated in this order, and two sheets so that the resin adhesive layer 8 is on the inside.
  • the film is formed into a bag shape by overlapping the films and heat-sealing the ends.
  • the second container 9 is formed of a film made of a specific resin material, and is formed into a bag shape by overlapping two films and heat-sealing the end portions.
  • the lithium ion secondary battery of the present embodiment includes a positive electrode (positive electrode plate).
  • the positive electrode (positive electrode plate) includes a positive electrode current collector and a positive electrode mixture disposed on the surface thereof.
  • the positive electrode mixture is a layer (positive electrode active material layer) including at least a positive electrode active material disposed on the surface of the positive electrode current collector.
  • the positive electrode active material layer may include a conductive material, a binder, a thickener, and the like in addition to the positive electrode active material.
  • a lithium-containing composite metal oxide is preferable.
  • the lithium-containing composite metal oxide include Li x CoO 2 , Li x NiO 2 , Li x MnO 2 , Li x Co y Ni 1-y O 2 , Li x Co y M 1-y O z , and Li x.
  • the value of x indicating the molar ratio of lithium is increased or decreased by charging and discharging.
  • An olivine type lithium salt or a chalcogen compound may be used as the positive electrode active material.
  • the olivine type lithium salt include LiFePO 4 .
  • the chalcogen compound include titanium disulfide and molybdenum disulfide.
  • a positive electrode active material may be used individually by 1 type, or may use 2 or more types together.
  • the positive electrode active material from the viewpoint of safety, it is preferred to include a lithium manganese oxide represented by Li x Mn 2 O 4 or Li x Mn 2-y M y O 4.
  • the content is preferably 30% by mass or more, and more preferably 40% by mass or more based on the total amount of the positive electrode active material.
  • Examples of the conductive material that may be used for the positive electrode active material layer include carbon black, graphite, carbon fiber, and metal fiber.
  • Examples of carbon black include acetylene black, ketjen black, channel black, furnace black, lamp black, and thermal black.
  • Examples of graphite include natural graphite and artificial graphite.
  • a conductive material may be used individually by 1 type, or may be used in combination of 2 or more type.
  • binder examples include polyethylene, polypropylene, polyvinyl acetate, polymethyl methacrylate, nitrocellulose, fluororesin, and rubber particles.
  • fluororesin examples include polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), and vinylidene fluoride-hexafluoropropylene copolymer.
  • rubber particles examples include styrene-butadiene rubber particles and acrylonitrile rubber particles.
  • a binder may be used individually by 1 type, or may be used in combination of 2 or more type.
  • the material of the positive electrode current collector is not particularly limited, and 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 positive electrode current collector is not particularly limited, and materials processed into various shapes can be used.
  • the 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
  • the carbonaceous material includes a carbon plate, a carbon thin film, A carbon cylinder etc. are mentioned. Among these, it is preferable to use a metal thin film. In addition, you may form a thin film in mesh shape as needed.
  • the thickness of the thin film is arbitrary, it is preferably 1 ⁇ m or more, more preferably 3 ⁇ m or more, and further preferably 5 ⁇ m or more.
  • the thickness of the thin film is preferably 1 mm or less, more preferably 100 ⁇ m or less, and further preferably 50 ⁇ m or less.
  • the thickness of the thin film is 1 ⁇ m or more, the strength required for the current collector tends to be obtained. Further, when the thickness of the thin film is 1 mm or less, sufficient flexibility is obtained and the workability tends to be good.
  • the positive electrode active material layer can be formed, for example, by applying a positive electrode mixture paste on the surface of the positive electrode current collector, drying, and rolling as necessary.
  • the positive electrode mixture paste can be prepared, for example, by adding a positive electrode active material to a dispersion medium together with a binder, a conductive material, a thickener, and the like as necessary.
  • the dispersion medium include N-methyl-2-pyrrolidone (NMP) and water.
  • the lithium ion secondary battery of the present embodiment includes a negative electrode (negative electrode plate).
  • the negative electrode (negative electrode plate) includes a negative electrode current collector and a negative electrode active material layer disposed on the surface thereof.
  • the negative electrode current collector include sheets and foils containing stainless steel, nickel, copper, and the like.
  • the thickness of the sheet and foil is not particularly limited, but is preferably, for example, 1 ⁇ m to 500 ⁇ m, more preferably 2 ⁇ m to 100 ⁇ m, and still more preferably 5 ⁇ m to 50 ⁇ m.
  • the negative electrode active material layer is formed on one or both surfaces in the thickness direction of the negative electrode current collector, contains the negative electrode active material, and further contains a binder, a conductive material, a thickener and the like as necessary. It may be.
  • the negative electrode active material a material capable of occluding and releasing lithium ions, which is commonly used in the field of lithium ion secondary batteries can be used.
  • the negative electrode active material include lithium metal, lithium alloy, intermetallic compound, carbon material, inorganic compound, metal complex, and organic polymer compound.
  • the inorganic compound include lithium titanium composite oxide and silicon carbide.
  • a negative electrode active material may be used individually by 1 type, or may be used in combination of 2 or more type.
  • a carbon material is preferable as the negative electrode active material.
  • the carbon material include graphite, carbon black, amorphous carbon, and carbon fiber. Examples of graphite include natural graphite such as flake graphite, and artificial graphite.
  • Examples of carbon black include acetylene black, ketjen black, channel black, furnace black, lamp black, and thermal black.
  • the volume average particle size of the carbon material is preferably 0.1 ⁇ m to 60 ⁇ m, and more preferably 0.5 ⁇ m to 30 ⁇ m.
  • the BET specific surface area of the carbon material is preferably 1 m 2 / g to 10 m 2 / g.
  • the carbon material is preferably selected in consideration of characteristics that are important in accordance with the use of the lithium ion secondary battery.
  • the distance between the carbon hexagonal planes (d 002 ) in the X-ray wide angle diffraction method is 3.35 to 3.40 and crystallites (Lc) in the c-axis direction are Graphite that is 100% or more is preferred.
  • amorphous carbon having an interval (d 002 ) between carbon hexagonal planes in the X-ray wide angle diffraction method of 3.5 to 3.95 mm is preferable.
  • the conductive material that may be used for the negative electrode active material layer the same conductive material as that contained in the positive electrode active material layer can be used.
  • a binder which may be used for a negative electrode active material layer what is commonly used in the field of lithium ion secondary batteries can be used. Examples thereof include polyethylene, polypropylene, polytetrafluoroethylene, polyvinylidene fluoride, styrene butadiene rubber, and acrylic rubber.
  • the thickener that may be used for the negative electrode active material layer include carboxymethylcellulose.
  • the negative electrode active material layer can be formed, for example, by applying a negative electrode mixture paste to the surface of the negative electrode current collector, drying, and rolling as necessary.
  • the negative electrode mixture paste can be prepared, for example, by adding a negative electrode active material to a dispersion medium together with a binder, a conductive material, a thickener, and the like as necessary.
  • the dispersion medium include N-methyl-2-pyrrolidone (NMP) and water.
  • the lithium ion secondary battery of the present embodiment includes an electrolytic solution.
  • the electrolytic solution is composed of a lithium salt (electrolyte) and a solvent that dissolves the lithium salt. You may add an additive as needed.
  • the lithium salt is not particularly limited as long as it is a lithium salt that can be used as an electrolyte of an electrolyte solution for a lithium ion battery.
  • the following inorganic lithium salts, fluorine-containing organic lithium salts, oxalate borate salts and the like can be mentioned.
  • inorganic lithium salt LiPF 6, LiBF 4, LiAsF 6, LiSbF 6 inorganic fluoride salts, such as, LiClO 4, Libro 4, perhalogenate of LiIO 4, etc., and the like inorganic chloride salts such as LiAlCl 4 It is done.
  • 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 4 F 9 SO 2) perfluoroalkanesulfonyl imide salts such as, LiC (CF 3 SO 2) perfluoroalkanesulfonyl methide salts such 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 3 (CF 2 CF 2 CF 3 )], Li [PF 4 (CF 2 CF 2 CF 2 CF 3 ) 2 ], Li [PF 3 (CF 2 CF
  • oxalatoborate salt examples include lithium bis (oxalato) borate and lithium difluorooxalatoborate.
  • lithium salts may be used alone or in combination of two or more.
  • lithium hexafluorophosphate LiPF 6
  • LiPF 6 lithium hexafluorophosphate
  • the concentration of the electrolyte in the electrolytic solution is not particularly limited, but is preferably 0.5 mol / L or more, more preferably 0.6 mol / L or more, and further preferably 0.7 mol / L or more. preferable.
  • the concentration of the electrolyte is preferably 2 mol / L or less, more preferably 1.8 mol / L or less, and still more preferably 1.7 mol / L or less.
  • the concentration of the electrolyte is 0.5 mol / L or more, the electric conductivity of the electrolytic solution tends to be sufficient.
  • the concentration of the electrolyte is 2 mol / L or less, the viscosity does not become too high, and good electric conductivity tends to be obtained.
  • the performance of a lithium ion secondary battery may fall by the fall of electrical conductivity.
  • the solvent is not particularly limited as long as it is a solvent that can be used as an electrolyte solvent for a lithium ion secondary battery, and examples thereof include cyclic carbonates, chain carbonates, chain esters, cyclic ethers, chain ethers, and the like.
  • 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.
  • a dialkyl carbonate is preferable, and the number of carbon atoms of the two alkyl groups is preferably 1 to 5, more preferably 1 to 4.
  • symmetrical chain carbonates such as dimethyl carbonate, diethyl carbonate, and di-n-propyl carbonate
  • asymmetric chain carbonates such as ethyl methyl carbonate, methyl-n-propyl carbonate, and ethyl-n-propyl carbonate Is mentioned.
  • dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate are preferable.
  • chain esters examples include methyl acetate, ethyl acetate, propyl acetate, and methyl propionate.
  • cyclic ether examples include tetrahydrofuran, 2-methyltetrahydrofuran, tetrahydropyran and the like.
  • chain ethers examples include dimethoxyethane and dimethoxymethane.
  • the electrolytic solution preferably contains a cyclic carbonate and a chain carbonate (a mixed solvent of a cyclic carbonate and a chain carbonate).
  • a cyclic carbonate and a chain carbonate a mixed solvent of a cyclic carbonate and a chain carbonate.
  • the cyclic carbonate / chain carbonate (volume ratio) is preferably 1/9 to 6/4, more preferably 2/8 to 5/5.
  • the electrolytic solution is preferably a mixture of a cyclic carbonate and a chain carbonate with a fluorine-containing cyclic carbonate or a compound having an unsaturated bond in the molecule.
  • fluorine-containing cyclic carbonate include fluoroethylene carbonate, difluoroethylene carbonate, trifluoroethylene carbonate, tetrafluoroethylene carbonate, and trifluoropropylene carbonate.
  • the compound having an unsaturated bond in the molecule include vinylene carbonate.
  • the lithium ion secondary battery of this embodiment includes a separator.
  • the separator is not particularly limited as long as it has ion permeability while electronically insulating between the positive electrode and the negative electrode, and has resistance to oxidation on the positive electrode side and reducibility on the negative electrode side.
  • a material (material) of the separator satisfying such characteristics a resin, an inorganic material, glass fiber, or the like is used.
  • the resin examples include olefin resin, fluororesin, cellulose resin, polyimide resin, and nylon resin. Among them, it is preferable to select from materials that are stable with respect to an electrolyte solution such as an olefin resin and have excellent liquid retention properties. It is more preferable to use a porous sheet, a nonwoven fabric, or the like made of an olefin resin such as polyethylene or polypropylene. preferable.
  • the inorganic substance examples 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.
  • oxides such as alumina and silicon dioxide
  • nitrides such as aluminum nitride and silicon nitride
  • sulfates such as barium sulfate and calcium sulfate.
  • thin film-shaped base materials such as a nonwoven fabric, a woven fabric, and a microporous film
  • the thin film-shaped substrate those having a pore diameter of 0.01 ⁇ m to 1 ⁇ m and a thickness of 5 ⁇ m to 50 ⁇ m are preferably used.
  • a composite porous layer may be formed by applying a mixture of an inorganic substance and a binder to the surface of the positive electrode or the negative electrode to form a separator.
  • a composite porous layer in which alumina particles having a 90% particle size of less than 1 ⁇ m are bound using a fluororesin as a binder may be formed on the surface of the positive electrode.
  • the lithium ion secondary battery of the present embodiment may include components other than those described above as necessary.
  • a cleavage valve may be provided. By opening the cleavage valve, it is possible to suppress an increase in pressure inside the battery and to improve safety. Moreover, you may provide the structure part which discharge
  • the electrode winding group in which the strip-like positive electrode plate 2 and the negative electrode plate 3 are wound in a spiral shape via the separator 4 has a bottomed cylindrical shape. It has a structure accommodated inside the battery container. In the space existing at the center of the electrode winding group, a structure 1 in which a specific flame retardant is disposed inside the container is provided. The inside of the battery container is filled with an electrolyte solution (not shown).
  • the structure 1 is provided inside the battery container.
  • the structure is provided in the space that exists in the center of the electrode winding group, but not limited to this, the space between the electrode winding group and the battery container bottom surface, the electrode winding group and the battery lid You may provide a structure in the space between.
  • a plurality of structures may be provided at different positions.
  • the battery container is made of nickel-plated steel
  • the separator 4 is a polyethylene porous sheet.
  • a ribbon-shaped positive electrode tab terminal made of aluminum and having one end fixed to the positive electrode plate 2 is led out from the upper end surface of the electrode winding group.
  • the other end of the positive electrode tab terminal is disposed on the upper side of the electrode winding group, and is joined by ultrasonic welding to the lower surface of a disk-shaped battery lid serving as a positive electrode external terminal.
  • a ribbon-like negative electrode tab terminal made of copper having one end fixed to the negative electrode plate 3 is led out on the lower end surface of the electrode winding group.
  • the other end of the negative electrode tab terminal is joined to the inner bottom of the battery container by resistance welding.
  • the positive electrode tab terminal and the negative electrode tab terminal are respectively led out to the opposite sides of the both end faces of the electrode winding group.
  • An insulating coating is applied to the outer peripheral surface of the electrode winding group.
  • the battery lid is caulked and fixed to the upper part of the battery container via an insulating resin gasket, and the inside of the lithium ion secondary battery is sealed. A non-aqueous electrolyte is injected into the battery container.
  • the lithium ion secondary battery according to the present disclosure is particularly suitable for a large capacity battery having a discharge capacity of 30 Ah or more and less than 99 Ah, but is also effective for a 18650 type small capacity lithium ion secondary battery.
  • Example 1 (1) Production of structure An aluminum laminate film (trade name: Rami Zip, ASONE Co., Ltd.) with an aluminum foil (Al) sandwiched between a polyethylene terephthalate (PET) film and a polyethylene (PE) film is about 1 cm long and about 5 cm wide. Two pieces cut to the size of were prepared. The cut aluminum laminate films were stacked and formed into a bag shape by heat-sealing with a table sealer (trade name: T-130K, Fuji Impulse Co., Ltd.) having a width of about 0.35 cm on each of the three sides.
  • a table sealer trade name: T-130K, Fuji Impulse Co., Ltd.
  • negative electrode 91.4 parts by mass of amorphous carbon (negative electrode active material), 66.15 parts by mass of polyvinylidene fluoride solution (binder, solid content 13% by mass), and N-methyl-2-pyrrolidone (NMP) 27.6 parts by mass were mixed to prepare a negative electrode mixture paste.
  • This negative electrode mixture paste was applied to both sides of a 10 ⁇ m thick copper core material (negative electrode current collector, Hitachi Cable Co., Ltd.), dried at 80 ° C. and then rolled, with a single-side thickness of 80 ⁇ m and a single-side coating amount of 80 g / m. 2.
  • a negative electrode active material layer having a mixture density of 1.1 g / cm 3 was formed to produce a negative electrode.
  • positive electrode LiMn 2 O 4 positive electrode active material, Mitsui Kinzoku Co., Ltd.
  • positive electrode active material positive electrode active material, Mitsui Kinzoku Co., Ltd.
  • acetylene black conductive material, trade name: HS-100, average particle size 48 nm (value described in manufacturer catalog), Electrochemical Industry Co., Ltd.
  • 100 parts by weight of a polyvinylidene fluoride solution binder, solid content 5% by weight
  • NMP N-methyl-2-pyrrolidone
  • a positive electrode active material layer of 2.1 g / cm 3 was formed to produce a positive electrode.
  • Lithium Ion Secondary Battery A product obtained by sandwiching a separator made of a polyethylene microporous film having a thickness of 30 ⁇ m and a width of 58.5 mm between the produced positive electrode and negative electrode was wound to obtain an electrode winding group. Produced. This electrode winding group was inserted into a battery container, and a negative electrode tab terminal previously welded to the negative electrode current collector was welded to the bottom of the can. Next, LiPF 6 was dissolved to a concentration of 1.2 mol / L in a solvent in which ethylene carbonate and dimethyl carbonate were mixed at a volume ratio of 2: 3, and vinylene carbonate was further added at 0.8% by mass. The electrolyte was prepared by adding.
  • the capacity retention rate after the battery after the test was held at 60 ° C. for 1 week was calculated. Specifically, the battery after the test was held at 60 ° C. for 1 week using a constant temperature dryer. After that, the battery is charged to 4.2 V at a charging current value of 0.5 C, and after performing constant current and constant voltage (CCCV) charging until the current value of 0.01 C as a termination condition is reached, to 3 V at a discharging current value of 0.5 C. A constant current (CC) discharge was performed, the discharge capacity at this time was measured, and this was defined as the discharge capacity after holding at 60 ° C. for 1 week.
  • Thermogravimetric analysis was performed to verify the weight loss onset temperature as an indicator of the temperature at which the flame retardant is released.
  • the structure for TGA measurement is cut into two pieces of aluminum laminate film (trade name: Rami Zip, ASONE Co., Ltd.) in a size of about 1 cm in length and 1 cm in width, and the cut aluminum laminate film is overlapped to make the width of each of the three sides.
  • About 0.4 cm is heat-sealed with a desktop sealer (trade name: T-130K, Fuji Impulse Co., Ltd.) to form a bag. After injecting 5 mg of carbon tetrabromide from the opening, the opening is Sealed by heat sealing.
  • the burner test is a test in which the upper end portion (positive electrode end portion) of a 18650 type lithium ion secondary battery is heated with a gas burner, which verifies the combustibility and self-extinguishing properties of the gas ejected due to the increase in internal pressure. it can. Specifically, immediately after igniting the ejected gas, heating by the gas burner was stopped, and the time taken for the fired ejected gas to extinguish was measured. It was evaluated that the shorter the time, the higher the self-extinguishing property of the electrolyte. The evaluation criteria were A if the time from ignition to extinction was less than 0.5 seconds, B if 0.5 seconds or more and less than 10 seconds, and C if 10 seconds or more. The results are shown in Table 1.
  • Example 2 A structure was produced in the same manner as in Example 1 except that the flame retardant was changed to 15% by mass of bromoform with respect to the total amount of the electrolytic solution.
  • a lithium ion secondary battery was prepared and evaluated in the same manner as in Example 1 except that this structure was used.
  • Example 3 A structure was prepared in the same manner as in Example 1 except that an aluminum foil was used instead of the aluminum laminate film, and four sides were bonded with an epoxy resin adhesive. Specifically, a two-part epoxy resin adhesive (trade name: two-part epoxy resin TB2086N, Three Bond Co., Ltd.) is applied to three sides of two 12 ⁇ m thick aluminum foils cut to the same size as in Example 1. After the same amount of carbon tetrabromide as in Example 1 was injected into the bag-like material that was cured and adhered at room temperature (25 ° C.) for 24 hours, the opening was sealed with the adhesive. It was produced with. A lithium ion secondary battery was prepared and evaluated in the same manner as in Example 1 except that this structure was used. The results are shown in Table 1.
  • Example 4 A structure was prepared in the same manner as in Example 1 except that an aluminum foil was used instead of the aluminum laminate film, and four sides were bonded with an acrylate resin adhesive. Specifically, three sides of two 12 ⁇ m thick aluminum foils cut to the same size as in Example 1 were used for 1 hour using an acrylate resin adhesive (trade name: Aron Alpha EXTRA impact resistance, Konishi Co., Ltd.). It was prepared by injecting the same amount of carbon tetrabromide as in Example 1 into a bag-like material that was cured and adhered at room temperature (25 ° C.), and then the opening was sealed with the above adhesive. A lithium ion secondary battery was prepared and evaluated in the same manner as in Example 1 except that this structure was used. The results are shown in Table 1.
  • Example 1 A structure was produced in the same manner as in Example 1 except that a polyethylene (PE) film was used instead of the aluminum laminate film. A lithium ion secondary battery was prepared and evaluated in the same manner as in Example 1 except that this structure was used. The results are shown in Table 1.
  • PE polyethylene
  • Example 2 A structure was produced in the same manner as in Example 1 except that a polyethylene terephthalate (PET) film was used instead of the aluminum laminate film. A lithium ion secondary battery was prepared and evaluated in the same manner as in Example 1 except that this structure was used. The results are shown in Table 1.
  • PET polyethylene terephthalate
  • Example 3 A lithium ion secondary battery was prepared in the same manner as in Example 1 except that carbon tetrabromide was not placed in a bag-shaped container made of an aluminum laminate film but directly placed in the cylindrical space at the center of the electrode winding group. Were prepared and evaluated. The results are shown in Table 1.
  • Example 5 The structure was the same as in Example 1 except that the flame retardant was 1,2-bis (2,3,4,5,6-pentabromophenyl) ethane in an amount of 15% by mass with respect to the total amount of the electrolyte. A product was made. A lithium ion secondary battery was prepared and evaluated in the same manner as in Example 1 except that this structure was used. For the structure for TGA measurement, 5 mg of 1,2-bis (2,3,4,5,6-pentabromophenyl) ethane was used as a flame retardant. The results are shown in Table 1.
  • Examples 1 to 4 in which the material of the structural body contains aluminum the weight reduction starting temperature was 90 ° C. or more. From this, the flame retardant is not released to the outside of the container at the normal use temperature (less than 80 ° C.) of the battery, and the flame retardant is released to the outside of the container when the battery becomes abnormal after exceeding 90 ° C. I found out. Further, from the results of the initial charge / discharge efficiency and the discharge rate characteristics, it was found that Examples 1 to 4 had the same battery performance as the conventional example (Comparative Example 6). Furthermore, Examples 1 to 4 using carbon tetrabromide or bromoform as the flame retardant were found to be excellent in self-extinguishing properties.
  • Comparative Example 1 The battery performance of Comparative Example 1 in which the material of the structural body was a polyethylene film was low. Moreover, the weight reduction start temperature was as low as 60 ° C. From this, it is considered that the flame retardant was mixed in the electrolyte even under normal use temperature, and the battery performance was lowered.
  • Comparative Example 2 in which the material of the structural body was a polyethylene terephthalate film, the initial charge and discharge efficiency and the discharge rate characteristics were the same as in Examples 1 to 4, but the capacity retention rate was low. This is probably because the flame retardant leaked from the container and mixed into the electrolyte.
  • Comparative Example 3 in which carbon tetrabromide was not put inside the container but directly inside the battery, the battery characteristics were remarkably deteriorated and measurement was impossible. Moreover, the weight reduction start temperature was as low as 32 ° C. From this, it is considered that the flame retardant was mixed in the electrolyte even under normal use temperature, and the battery performance was lowered.
  • a bag-like container 2A (second container) containing a flame retardant having a length of about 0.5 cm and a width of about 4.5 cm was produced.
  • an aluminum laminate film (trade name: Rami Zip, ASONE Co., Ltd.) in which an aluminum foil (Al) is sandwiched between a polyethylene terephthalate (PET) film and a polyethylene (PE) film is about 1.4 cm long and about 5.4 cm wide. Two pieces cut to the size of were prepared.
  • the laminated aluminum laminate film is stacked so that the polyethylene films are in contact with each other, and the three sides are each 0.35 cm wide and heat-sealed with a desktop sealer (trade name: T-130K, Fuji Impulse Co., Ltd.).
  • the container 1A (first container) was produced. After inserting the bag-shaped container 2A containing the flame retardant into the container 1A, the opening was sealed by heat-sealing. The four sides of the fused part were cut out leaving a width of 0.1 cm to produce a bag-like structure A containing a flame retardant having a length of about 0.7 cm and a width of about 4.7 cm.
  • negative electrode 91.4 parts by mass of amorphous carbon (negative electrode active material), 66.15 parts by mass of polyvinylidene fluoride solution (binder, solid content 13% by mass), and N-methyl-2-pyrrolidone (NMP) 27.6 parts by mass were mixed to prepare a negative electrode mixture paste.
  • This negative electrode mixture paste was applied to both sides of a 10 ⁇ m thick copper core material (negative electrode current collector, Hitachi Cable Co., Ltd.), dried at 80 ° C. and then rolled, with a single-side thickness of 80 ⁇ m and a single-side coating amount of 80 g / m. 2.
  • a negative electrode active material layer having a mixture density of 1.1 g / cm 3 was formed to produce a negative electrode.
  • positive electrode LiMn 2 O 4 positive electrode active material, Mitsui Kinzoku Co., Ltd.
  • positive electrode active material positive electrode active material, Mitsui Kinzoku Co., Ltd.
  • acetylene black conductive material, trade name: HS-100, average particle size 48 nm (value described in manufacturer catalog), Electrochemical Industry Co., Ltd.
  • 100 parts by weight of a polyvinylidene fluoride solution binder, solid content 5% by weight
  • NMP N-methyl-2-pyrrolidone
  • a positive electrode active material layer having a thickness of 1 g / cm 3 was formed to produce a positive electrode.
  • Lithium Ion Secondary Battery A product obtained by sandwiching a separator made of a polyethylene microporous film having a thickness of 30 ⁇ m and a width of 58.5 mm between the produced positive electrode and negative electrode was wound to obtain an electrode winding group. Produced. This electrode winding group was inserted into a battery container, and a negative electrode tab terminal previously welded to the negative electrode current collector was welded to the bottom of the can. Next, LiPF 6 was dissolved to a concentration of 1.2 mol / L in a solvent in which ethylene carbonate and dimethyl carbonate were mixed at a volume ratio of 2: 3, and vinylene carbonate was further added at 0.8% by mass. The electrolyte was prepared by adding.
  • the capacity retention rate after the battery after the test was held at 80 ° C. for 1 week was calculated. Specifically, the battery after the test was held at 80 ° C. for 1 week using a constant temperature dryer. After that, the battery is charged to 4.2 V at a charging current value of 0.5 C, and after performing constant current and constant voltage (CCCV) charging until the current value of 0.01 C as a termination condition is reached, to 3 V at a discharging current value of 0.5 C. A constant current (CC) discharge was performed, the discharge capacity at this time was measured, and this was defined as the discharge capacity after holding at 80 ° C. for 1 week.
  • the structure for measurement was produced by the following method. First, two pieces of a polyethylene terephthalate (PET) film having a thickness of 125 ⁇ m cut into a size of about 3 cm in length and about 3 cm in width were prepared. The cut polyethylene terephthalate films were stacked and formed into a bag shape by heat-sealing with a table sealer (trade name: T-130K, Fuji Impulse Co., Ltd.) having a width of about 0.5 cm on each of the three sides.
  • PET polyethylene terephthalate
  • a container 2B (second container).
  • an aluminum laminate film (trade name: Rami Zip, ASONE Co., Ltd.) in which an aluminum foil (Al) is sandwiched between a polyethylene terephthalate (PET) film and a polyethylene (PE) film is sized 5 cm long and 5 cm wide. Two cut pieces were prepared.
  • the laminated aluminum laminate film is stacked so that the polyethylene films are in contact with each other, and each side is about 0.5 cm wide and heat sealed with a desktop sealer (trade name: T-130K, Fuji Impulse Co., Ltd.).
  • the container 1B (first container) was produced.
  • the container 2B was inserted into the container 1B, and the opening was sealed by heat-sealing to produce a structure B.
  • the weight loss rate was measured.
  • the temperature of the dryer was increased by 20 ° C., and the weight reduction rate after heating again for 1 hour was measured.
  • the above measurement was repeated until the weight decreased by 1% or more, or until 200 ° C., and the temperature at which the weight decreased by 1% or more was defined as the weight reduction start temperature.
  • Table 2 The results are shown in Table 2.
  • the burner test is a test in which the upper end portion (positive electrode end portion) of a 18650 type lithium ion secondary battery is heated with a gas burner, which verifies the combustibility and self-extinguishing properties of the gas ejected due to the increase in internal pressure. it can. Specifically, immediately after igniting the ejected gas, heating by the gas burner was stopped, and the time taken for the fired ejected gas to extinguish was measured. It was evaluated that the shorter the time, the higher the self-extinguishing property of the electrolyte. The evaluation criteria were A if the time from ignition to extinction was less than 0.5 seconds, B if 0.5 seconds or more and less than 10 seconds, and C if 10 seconds or more. The results are shown in Table 2.
  • Example 6 A structure was produced in the same manner as in Example 5 except that the material of the container 2A and the container 2B enclosing the carbon tetrabromide was a 70 ⁇ m-thick polypropylene (PP) film. A lithium ion secondary battery was produced and evaluated in the same manner as in Example 5 except that this structure was used. The results are shown in Table 2.
  • Example 7 A structure was prepared in the same manner as in Example 5 except that the flame retardant was bromoform in an amount of 15% by mass with respect to the total amount of the electrolyte.
  • a lithium ion secondary battery was produced and evaluated in the same manner as in Example 5 except that this structure was used.
  • 1 g of bromoform was used as a flame retardant. The results are shown in Table 2.
  • Example 8> As a material of the container 1A and the container 1B, an aluminum foil was used instead of the aluminum laminate film, and a structure was produced in the same manner as in Example 5 except that four sides were bonded with an epoxy resin adhesive. Specifically, two sides of two 12 ⁇ m-thick aluminum foils cut to the same size as in Example 5 were two-component epoxy resin adhesive (trade name: two-component epoxy resin TB2086N, Three Bond Co., Ltd.) After the same container 2A or container 2B as in Example 5 is inserted into a bag-like material that is cured and adhered at room temperature (25 ° C.) for 24 hours, the opening is sealed with the above adhesive. Thus, a structure was produced. A lithium ion secondary battery was produced and evaluated in the same manner as in Example 5 except that this structure was used. The results are shown in Table 2.
  • Example 9 In Structure A and Structure B, a structure was produced in the same manner as in Example 5 except that carbon tetrabromide was directly added to the inside of the container 1A and the container 1B as in Example 5. A lithium ion secondary battery was produced and evaluated in the same manner as in Example 5 except that this structure was used. The results are shown in Table 2.
  • Example 10 As materials for the container 1A and the container 1B, a polypropylene (PP) film that is a resin adhesive layer (that is, the innermost layer), an aluminum foil (Al) that is a metal layer, and nylon that is a resin surface layer (that is, the outermost layer) Ny) A structure was prepared in the same manner as in Example 9, except that an aluminum laminate film having a three-layer structure of film was used. A lithium ion secondary battery was produced and evaluated in the same manner as in Example 5 except that this structure was used. The results are shown in Table 2.
  • PP polypropylene
  • Al aluminum foil
  • nylon that is a resin surface layer
  • Example 11 In the structure A and the structure B, a structure was produced in the same manner as in Example 5 except that the material of the container 2A and the container 2B was changed to a polyethylene (PE) film. A lithium ion secondary battery was produced and evaluated in the same manner as in Example 5 except that this structure was used. The results are shown in Table 2.
  • Example 8 A lithium ion secondary battery was fabricated and evaluated in the same manner as in Example 5 except that carbon tetrabromide was not placed in the bag-shaped container but directly placed in the cylindrical space at the center of the electrode winding group. Went. The results are shown in Table 2. For the weight measurement during heating, 1 g of carbon tetrabromide was used as it was without using the structure B. In Comparative Example 8, since the structure B was not used, the corrosion resistance test was not performed.
  • Examples 5 to 8 which contain aluminum in the material of the container 1B and further contain the container 2B made of a polyethylene terephthalate film or a polypropylene film inside the container 1B Were 100 ° C. or higher. From this, it can be expected that the flame retardant is not released to the outside of the structure at the normal use temperature (less than 80 ° C.) of the battery, and is released to the outside after reaching a high temperature state (100 ° C. or more). In the corrosion resistance test, in Examples 5 to 8, no corrosion was observed in the aluminum of the container 1A. Therefore, it was suggested that the container 2A composed of a polyethylene terephthalate film or a polypropylene film suppressed corrosion of aluminum by the flame retardant.
  • Examples 5 to 8 had the same battery performance as the conventional example (Comparative Example 9). Furthermore, it can be seen that Examples 5 to 8 using carbon tetrabromide or bromoform as the flame retardant are excellent in self-extinguishing properties.
  • Example 9 and Example 10 in which aluminum is contained in the material of the container 1B and the container 2B is not used, and Example 11 in which the container 2B is made of a polyethylene film are the structures B in the corrosion resistance test.
  • the initial charge / discharge efficiency and discharge rate characteristics were the same as those in Examples 5 to 8, but the capacity retention rate was slightly lower than that in Examples 5 to 8. This is presumably because aluminum was corroded at 80 ° C., and the flame retardant leaked from the structure A and mixed into the electrolyte.
  • Comparative Example 7 in which the material of the container 2A is a polyethylene terephthalate film, the initial charge and discharge efficiency and the discharge rate characteristics were the same as those in Examples 5 to 8, but the capacity retention rate was compared with Examples 5 to 8. And then dropped. This is presumably because the flame retardant leaked from the structure A and mixed into the electrolyte.
  • Comparative Example 8 in which carbon tetrabromide was directly arranged inside the battery, the battery characteristics were remarkably deteriorated and measurement was impossible. This is presumed that the flame retardant was mixed in the electrolyte even under normal use temperature, resulting in a decrease in battery performance.
  • the lithium ion secondary battery of the present disclosure a dangerous state can be effectively suppressed under a temperature rise.
  • the metal constituting the structure by the halogen-based compound is not corroded, and the flame retardant is contained in the electrolyte when the normal battery is used. It was found that it was not released and the battery performance was not impaired.

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PCT/JP2015/071860 2014-08-07 2015-07-31 リチウムイオン二次電池 WO2016021513A1 (ja)

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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH0922723A (ja) * 1995-07-07 1997-01-21 Toshiba Corp リチウムイオン二次電池用電解液およびそれを用いたリチウムイオン二次電池
JP2001076759A (ja) * 1999-08-31 2001-03-23 Sanyo Electronic Components Co Ltd 電気化学デバイス
JP5218967B2 (ja) * 2008-06-11 2013-06-26 三菱重工業株式会社 二次電池

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH0922723A (ja) * 1995-07-07 1997-01-21 Toshiba Corp リチウムイオン二次電池用電解液およびそれを用いたリチウムイオン二次電池
JP2001076759A (ja) * 1999-08-31 2001-03-23 Sanyo Electronic Components Co Ltd 電気化学デバイス
JP5218967B2 (ja) * 2008-06-11 2013-06-26 三菱重工業株式会社 二次電池

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