WO2015159824A1 - Solution électrolytique non aqueuse pour batterie rechargeable, et batterie rechargeable au lithium-ion - Google Patents

Solution électrolytique non aqueuse pour batterie rechargeable, et batterie rechargeable au lithium-ion Download PDF

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WO2015159824A1
WO2015159824A1 PCT/JP2015/061262 JP2015061262W WO2015159824A1 WO 2015159824 A1 WO2015159824 A1 WO 2015159824A1 JP 2015061262 W JP2015061262 W JP 2015061262W WO 2015159824 A1 WO2015159824 A1 WO 2015159824A1
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compound
mass
carbon atoms
fluorine
secondary battery
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PCT/JP2015/061262
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Japanese (ja)
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祐 小野崎
室谷　英介
豊和 遠田
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旭硝子株式会社
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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
    • H01M10/0568—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
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Definitions

  • the present invention relates to a non-aqueous electrolyte for a secondary battery and a lithium ion secondary battery.
  • Non-aqueous electrolytes capable of obtaining a lithium ion secondary battery with good battery characteristics (cycle characteristics, rate characteristics, initial charge / discharge efficiency).
  • a lithium salt and a liquid composition wherein the liquid composition is at least one fluorine-containing solvent selected from the group consisting of a fluorine-containing ether compound, a fluorine-containing chain carboxylic acid ester compound, and a fluorine-containing chain carbonate compound;
  • a nonaqueous electrolytic solution containing a cyclic carboxylic acid ester compound and an unsaturated cyclic carbonate and / or a fluorinated cyclic carbonate Patent Document 1.
  • the battery characteristics (cycle characteristics, rate characteristics, initial charge / discharge efficiency) of the lithium ion secondary battery are still insufficient.
  • a non-aqueous electrolyte that can further improve the battery characteristics is desired.
  • An object of the present invention is to provide a non-aqueous electrolyte for a secondary battery capable of obtaining a lithium ion secondary battery excellent in battery characteristics (cycle characteristics, rate characteristics, initial charge / discharge efficiency), and battery characteristics (cycle characteristics, rate characteristics). It is to provide a lithium ion secondary battery having excellent initial charge / discharge efficiency.
  • a fluorine-containing solvent (A) containing a seed wherein the liquid composition comprises at least one selected from the group consisting of a fluorine-containing ether compound, a fluorine-containing chain carboxylic acid ester compound and a fluorine-containing chain carbonate compound;
  • a non-aqueous electrolyte for a secondary battery having a ratio of 0.01 to 20% by mass.
  • M is a boron atom or phosphorus atom
  • R 1 is an optionally substituted alkylene group having 1 to 10 carbon atoms
  • X is a halogen atom
  • n is 0 to It is an integer of 4
  • m is 0 or 1
  • p is 1 or 2.
  • R 14 to R 17 are each independently a hydrogen atom or an alkyl group having 1 to 6 carbon atoms.
  • the lithium salt is a compound represented by the following formula (1-1), a compound represented by the following formula (1-2), a compound represented by the following formula (1-3), 1-4) and a non-secondary battery for a secondary battery according to any one of [1] to [3], comprising at least one selected from the group consisting of a compound represented by 1-4) and a compound represented by the following formula (1-5): Water electrolyte.
  • the ratio of the mass of the compound represented by the formula (1) to the total mass of the nonaqueous electrolytic solution is 0.01 to 10% by mass, and any one of [1] to [4] Nonaqueous electrolyte for secondary batteries.
  • the fluorine-containing ether compound is at least one selected from the group consisting of a compound represented by the following formula (2) and a compound represented by the following formula (3): [1] to [5] A non-aqueous electrolyte for a secondary battery.
  • R 2 and R 3 are each independently an alkyl group having 1 to 10 carbon atoms, a cycloalkyl group having 3 to 10 carbon atoms, a fluorinated alkyl group having 1 to 10 carbon atoms, or a fluorinated group having 3 to 10 carbon atoms.
  • R 8 to R 13 are each independently a hydrogen atom, a fluorine atom, a chlorine atom, an alkyl group having 1 to 2 carbon atoms, a fluorinated alkyl group having 1 to 2 carbon atoms, or an etheric oxygen atom having 2 carbon atoms.
  • q is an integer of 0 to 3.
  • the fluorine-containing ether compound is CF 3 CH 2 OCF 2 CHF 2 , CF 3 CH 2 OCF 2 CHFCF 3 , CHF 2 CF 2 CH 2 OCF 2 CHF 2 , CH 3 CH 2 CH 2 OCF 2 CHF 2 , it is at least one selected from the group consisting of CH 3 CH 2 OCF 2 CHF 2 and CHF 2 CF 2 CH 2 OCF 2 CHFCF 3, [1] ⁇ any of the non-aqueous electrolyte solution for a secondary battery [7] .
  • the nonaqueous electrolytic solution for a secondary battery according to any one of [1] to [8], wherein the fluorine-containing solvent (A) is the fluorine-containing ether compound.
  • Non-aqueous electrolyte For the secondary battery according to any one of [1] to [12], wherein the ratio of the mass of the cyclic carboxylic acid ester compound (B) to the total mass of the non-aqueous electrolyte is 4 to 60% by mass.
  • Non-aqueous electrolyte A negative electrode using as an active material at least one selected from the group consisting of a positive electrode having a material capable of inserting and extracting lithium ions as an active material, and a lithium metal, a lithium alloy, and a carbon material capable of inserting and extracting lithium ions.
  • a non-aqueous electrolyte for secondary batteries according to any one of [1] to [13].
  • a lithium ion secondary battery excellent in battery characteristics (cycle characteristics, rate characteristics, initial charge / discharge efficiency) can be obtained.
  • the lithium ion secondary battery of the present invention is excellent in battery characteristics (cycle characteristics, rate characteristics, initial charge / discharge efficiency).
  • non-aqueous electrolyte is an electrolyte that does not substantially contain water, and even if water is included, the water content of the secondary battery using the non-aqueous electrolyte does not deteriorate in performance. It means an electrolyte solution in a range of amounts.
  • the amount of water that can be contained in the non-aqueous electrolyte is preferably 500 ppm by mass or less, more preferably 100 ppm by mass or less, and particularly preferably 50 ppm by mass or less with respect to the total mass of the non-aqueous electrolyte.
  • the lower limit of the moisture content is 0 mass ppm.
  • the “liquid composition” includes a fluorine-containing solvent (A), a cyclic carboxylic acid ester compound (B), and a saturated cyclic carbonate compound (C) having no fluorine atom.
  • the nonaqueous electrolytic solution in the present invention contains an electrolyte, a fluorine-containing solvent (A), a cyclic carboxylic acid ester compound (B), and a saturated cyclic carbonate compound (C) having no fluorine atom as essential components.
  • the “fluorinated ether compound” means a chain or cyclic compound having an ether bond and having a fluorine atom.
  • the “fluorinated chain carboxylic acid ester compound” means a chain compound having an ester bond in a chain structure and not having a ring structure having an ester bond and having a fluorine atom.
  • “Fluorine-containing chain carbonate compound” is a chain structure having a carbonate bond represented by —O—C ( ⁇ O) —O—, having no ring structure having a carbonate bond, and having a fluorine atom Means a chain-like compound having
  • the “fluorinated alkane compound” means a compound in which one or more hydrogen atoms of an alkane are substituted with fluorine atoms, and hydrogen atoms remain.
  • cyclic carboxylic acid ester compound means a cyclic compound having an ester bond as a part of the ring skeleton.
  • saturated cyclic carbonate compound having no fluorine atom means that a ring skeleton is composed of a carbon atom and an oxygen atom, and a carbonate bond represented by —O—C ( ⁇ O) —O— is formed as a part of the ring skeleton.
  • Fluorinated and “fluorinated” mean that some or all of the hydrogen atoms bonded to the carbon atom are replaced with fluorine atoms.
  • the “fluorinated alkyl group” means a group in which part or all of the hydrogen atoms of the alkyl group are substituted with fluorine atoms.
  • the partially fluorinated groups are hydrogen atoms and fluorine atoms.
  • the “perfluoroalkyl group” means a group in which all hydrogen atoms of an alkyl group are substituted with fluorine atoms.
  • Carbon-carbon unsaturated bond means a carbon-carbon double bond or a carbon-carbon triple bond.
  • the non-aqueous electrolyte for secondary batteries of the present invention includes an electrolyte and a liquid composition, and includes other components as necessary.
  • the lower limit of the ionic conductivity at 25 ° C. of the nonaqueous electrolytic solution is preferably 0.30 S / m. If the ionic conductivity at 25 ° C. of the non-aqueous electrolyte is 0.30 S / m or more, the battery characteristics of the secondary battery are further improved.
  • At least one of the electrolytes is a lithium salt.
  • the electrolyte may be a lithium salt alone or a combination of a lithium salt and an electrolyte other than the lithium salt.
  • Examples of the electrolyte other than the lithium salt include sodium salt or potassium salt of monofluorophosphoric acid or difluorophosphoric acid, NaPF 6 and the like.
  • the lithium salt dissociates in the non-aqueous electrolyte and supplies lithium ions.
  • the nonaqueous electrolytic solution contains the following compound (1) as an essential component as a lithium salt.
  • M is a boron atom or phosphorus atom
  • R 1 is an optionally substituted alkylene group having 1 to 10 carbon atoms
  • X is a halogen atom
  • n is 0 to It is an integer of 4
  • m is 0 or 1
  • p is 1 or 2.
  • n When M is a boron atom and p is 1, n is 2. When M is a boron atom and p is 2, n is 0. When M is a phosphorus atom and p is 1, n is 4. When M is a phosphorus atom and p is 2, n is 2. When p is 2, both m may be 0, both may be 1, one may be 0 and the other may be 1. When p is 2 and two m's are both 1, the two R 1 groups may be different from each other or the same group.
  • Examples of the substituent for R 1 include a halogen atom, a chain or cyclic alkyl group, an aryl group, a sulfonyl group, a cyano group, a hydroxyl group, and an alkoxy group.
  • X is preferably a fluorine atom or a chlorine atom, particularly preferably a fluorine atom.
  • the compound (1) one type may be used alone, or two or more types may be used in combination.
  • the non-aqueous electrolyte contains the compound (1) as a lithium salt
  • the non-aqueous electrolyte is excellent in battery characteristics such as cycle characteristics and rate characteristics.
  • the compound (1) decomposes on the negative electrode during charging of the secondary battery, and forms a lithium ion conductive film (SEI) having a small interface resistance on the negative electrode surface.
  • SEI lithium ion conductive film
  • vinylene carbonate etc. are known as a film formation agent which forms such SEI. Since the compound (1) can form a favorable SEI having a lower interface resistance than conventional film forming agents such as vinylene carbonate, it becomes a non-aqueous electrolyte excellent in battery characteristics such as cycle characteristics and rate characteristics. Conceivable.
  • the lithium salt is at least one selected from the group consisting of the following compounds (1-1) to (1-5) from the viewpoint of easily obtaining a non-aqueous electrolyte excellent in battery characteristics such as cycle characteristics and rate characteristics. It is preferable to contain.
  • the lithium salt may contain other lithium salts other than the compound (1).
  • Other lithium salts include LiPF 6 , Li 2 PO 3 F, LiPO 2 F 2 , the following compound (11) (where k is an integer of 1 to 5), FSO 2 N (Li) SO 2 F , CF 3 SO 2 N (Li ) SO 2 CF 3, CF 3 CF 2 SO 2 N (Li) SO 2 CF 2 CF 3, CF 3 CFHSO 2 N (Li) SO 2 CFHCF 3, LiClO 4, LiBF 4 , etc. Is mentioned.
  • LiPF 6 is preferably contained. That is, as the lithium salt, a combination of the compound (1) and LiPF 6 is particularly preferable. When LiPF 6 is included as the lithium salt, the ionic conductivity is good and the battery characteristics are excellent. Another lithium salt may be used individually by 1 type, and may be used in combination of 2 or more type.
  • the liquid composition contains a fluorinated solvent (A), a cyclic carboxylic acid ester compound (B), and a saturated cyclic carbonate compound (C) having no fluorine atom.
  • the fluorine-containing solvent (A) is a fluorine-containing solvent containing at least one selected from the group consisting of fluorine-containing ether compounds, fluorine-containing chain carboxylic acid ester compounds and fluorine-containing chain carbonate compounds.
  • the fluorine-containing solvent (A) is a solvent having a fluorine atom in the molecule and is excellent in flame retardancy.
  • a fluorine-containing solvent (A) may be used individually by 1 type, and may be used in combination of 2 or more type. When the number of fluorine-containing solvents (A) is two or more, the ratio can be arbitrarily determined.
  • the fluorine-containing solvent (A) preferably contains a fluorine-containing ether compound from the viewpoint of the solubility of the lithium salt, the flame retardancy, and the ionic conductivity of the non-aqueous electrolyte.
  • the fluorine-containing ether compound is at least one selected from the group consisting of the following compound (2) and the following compound (3) from the viewpoints of lithium salt solubility, flame retardancy, and ionic conductivity of the non-aqueous electrolyte. Species are preferred.
  • a fluorine-containing ether compound may be used individually by 1 type, and may be used in combination of 2 or more type. When the number of fluorine-containing ether compounds is two or more, the ratio can be arbitrarily determined.
  • R 2 and R 3 are each independently an alkyl group having 1 to 10 carbon atoms, a cycloalkyl group having 3 to 10 carbon atoms, a fluorinated alkyl group having 1 to 10 carbon atoms, carbon A fluorinated cycloalkyl group having 3 to 10 carbon atoms, an alkyl group having 2 to 10 carbon atoms having an etheric oxygen atom, or a fluorinated alkyl group having 2 to 10 carbon atoms having an etheric oxygen atom.
  • R 2 and R 3 is a fluorinated alkyl group having 1 to 10 carbon atoms, a fluorinated cycloalkyl group having 3 to 10 carbon atoms, or a carbon number having 2 to 10 carbon atoms having an etheric oxygen atom.
  • Y represents an alkylene group having 1 to 5 carbon atoms, a fluorinated alkylene group having 1 to 5 carbon atoms, an alkylene group having 2 to 5 carbon atoms having an etheric oxygen atom, or etheric oxygen A fluorinated alkylene group having 2 to 5 carbon atoms and having an atom.
  • Examples of the alkyl group and the alkyl group having an etheric oxygen atom in the compound (2) include a linear structure, a branched structure, or a group having a cyclic structure (cycloalkylalkyl group and the like).
  • R 2 and R 3 in the compound (2) is a fluorinated alkyl group having 1 to 10 carbon atoms, a fluorinated cycloalkyl group having 3 to 10 carbon atoms, or a carbon number having an etheric oxygen atom. 2 to 10 fluorinated alkyl groups.
  • R 2 and R 3 are these groups, the solubility of the lithium salt in the non-aqueous electrolyte and the flame retardancy of the non-aqueous electrolyte are excellent.
  • R 2 and R 3 in the compound (2) may be the same or different.
  • R 2 and R 3 are all fluorinated alkyl groups having 1 to 10 carbon atoms from the viewpoint of lithium salt solubility, flame retardancy, and ionic conductivity of the non-aqueous electrolyte.
  • Compound (2-A) Compound (2-A) wherein R 2 is a fluorinated alkyl group having 2 to 10 carbon atoms having an etheric oxygen atom, and R 3 is a fluorinated alkyl group having 1 to 10 carbon atoms B); or a compound (2-C) in which R 2 is a fluorinated alkyl group having 1 to 10 carbon atoms and R 3 is an alkyl group having 1 to 10 carbon atoms.
  • Compound (2-A) or compound (2-C) is more preferable, and compound (2-A) is particularly preferable.
  • the total number of carbon atoms in the compound (2) is preferably 4 to 10 and more preferably 4 to 8 from the viewpoint that the boiling point is too low when the amount is too small and the viscosity increases when the amount is too large.
  • the molecular weight of the compound (2) is preferably 150 to 800, more preferably 150 to 500, and particularly preferably 200 to 500 from the viewpoint that if the molecular weight is too small, the boiling point is too low, and if it is too large, the viscosity becomes high.
  • the number of etheric oxygen atoms in the compound (2) is preferably 1 to 4, more preferably 1 or 2, and even more preferably 1. The number of etheric oxygen atoms in the compound (2) affects flammability.
  • the fluorine content is the ratio of the total mass of fluorine atoms to the molecular weight.
  • both of R 2 and R 3 the compound partially fluorinated alkyl group of which a hydrogen atom is preferred, R 2 and A compound in which either one or both of the terminals of R 3 is CHF 2 is more preferable.
  • Specific examples of the compound (2-A) and the compound (2-B), and specific examples of the fluorinated ether compound other than the compound (2-A) and the compound (2-B) include International Publication No. 2009/133899. And the like.
  • CF 3 CH 2 OCF 2 CHF 2 (produced by Asahi Glass Co., Ltd., Asahi Clin AE-) has excellent lithium salt solubility, flame retardancy, low viscosity, and low boiling point. 3000), CF 3 CH 2 OCF 2 CHFCF 3, CHF 2 CF 2 CH 2 OCF 2 CHF 2, CH 3 CH 2 CH 2 OCF 2 CHF 2, CH 3 CH 2 OCF 2 CHF 2 and CHF 2 CF 2 CH 2 OCF
  • at least one selected from the group consisting of 2 CHFCF 3 is selected from the group consisting of CF 3 CH 2 OCF 2 CHF 2 , CHF 2 CF 2 CH 2 OCF 2 CHF 2 and CHF 2 CF 2 CH 2 OCF 2 CHFCF 3 At least one selected from the above is particularly preferred.
  • Y in the compound (3) may have a linear structure or a branched structure.
  • Y is preferably an alkylene group having 1 to 5 carbon atoms, more preferably an alkylene group having 2 to 4 carbon atoms.
  • the alkylene group preferably has a linear structure or a branched structure.
  • the side chain is preferably an alkyl group having 1 to 3 carbon atoms or an alkyl group having 1 to 3 carbon atoms having an etheric oxygen atom.
  • the compound (3) is selected from the group consisting of —CH 2 —, —CH 2 CH 2 —, —CH (CH 3 ) CH 2 — and —CH 2 CH 2 CH 2 — in the formula (3). And one or both of the compound in which Y is —CH 2 CH 2 — and the compound in which Y is —CH (CH 3 ) CH 2 — is more preferable, and Y is —CH 2. CH 2 -, compound and Y is -CH (CH 3) CH 2 - is still more preferably one of a compound. Specific examples of the compound (3) include a compound represented by the following formula.
  • fluorinated ether compound compound (2) alone, compound (3) alone, or a mixture of compound (2) and compound (3) is preferred, and compound (2) alone is more preferred.
  • a compound (2) may be used individually by 1 type, and may be used in combination of 2 or more type.
  • a compound (3) may be used individually by 1 type, and may be used in combination of 2 or more type.
  • Fluorine-containing chain carboxylic acid ester compound preferably contains the following compound (4), more preferably only the compound (4), from the viewpoints of viscosity, boiling point and the like.
  • a fluorine-containing chain carboxylic acid ester compound may be used individually by 1 type, and may be used in combination of 2 or more type. When the number of fluorine-containing chain carboxylic acid ester compounds is two or more, the ratio can be arbitrarily determined. When the compound (4) is included, the compound (4) may be used alone or in combination of two or more.
  • R 4 and R 5 are each independently an alkyl group having 1 to 3 carbon atoms or a fluorinated alkyl group having 1 to 3 carbon atoms, and one or both of R 4 and R 5 are 1 to 3 fluorinated alkyl groups.
  • Examples of the alkyl group and the fluorinated alkyl group in the compound (4) include a linear structure and a branched structure, respectively.
  • One or both of R 4 and R 5 are preferably a fluorinated alkyl group having 1 to 3 carbon atoms. By making one or both of R 4 and R 5 into a fluorinated alkyl group having 1 to 3 carbon atoms, the compound (4) is excellent in oxidation resistance and flame retardancy.
  • R 4 and R 5 in the compound (4) may be the same or different.
  • R 4 is preferably a methyl group, an ethyl group, a difluoromethyl group, a trifluoromethyl group, a tetrafluoroethyl group, or a pentafluoroethyl group from the viewpoint of viscosity, boiling point, or availability of the compound, and a difluoromethyl group, Or a trifluoromethyl group is more preferable.
  • R 5 is a methyl group, an ethyl group, a trifluoromethyl group, a 2-fluoroethyl group, a 2,2-difluoroethyl group, or 2,2,2-in terms of viscosity, boiling point, or availability of the compound.
  • a trifluoroethyl group is preferred, a methyl group, an ethyl group, or a 2,2,2-trifluoroethyl group is more preferred, and a methyl group or an ethyl group is more preferred.
  • the total number of carbon atoms in the compound (4) is preferably from 3 to 8, more preferably from 3 to 6, and even more preferably from 3 to 5 from the viewpoint that if the amount is too small, the boiling point is too low and if the amount is too large, the viscosity increases.
  • the molecular weight of the compound (4) is preferably from 100 to 300, more preferably from 100 to 250, and particularly preferably from 100 to 200 from the viewpoint that if the molecular weight is too small, the boiling point is too low, and if it is too large, the viscosity increases.
  • the fluorine content in the compound (4) is preferably 25% by mass or more and more preferably 30% by mass or more from the viewpoint of excellent flame retardancy. Moreover, since the affinity of lithium salt will fall and phase separation will become easy when there is too much, 55 mass% or less is preferable and 50 mass% or less is more preferable.
  • the compound (4) include acetic acid (2,2,2-trifluoroethyl), methyl difluoroacetate, ethyl difluoroacetate, ethyl trifluoroacetate and the like. From the viewpoint of availability and battery performance such as cycle characteristics, methyl difluoroacetate and ethyl trifluoroacetate are preferable.
  • Fluorine-containing chain carbonate compound preferably contains the following compound (5), more preferably only the compound (5), from the viewpoints of viscosity and boiling point.
  • a fluorine-containing chain carbonate compound may be used individually by 1 type, and may be used in combination of 2 or more type. When the number of fluorine-containing chain carbonate compounds is two or more, the ratio can be arbitrarily determined. When the compound (5) is contained, the compound (5) may be used alone or in combination of two or more.
  • R 6 and R 7 are each independently an alkyl group having 1 to 3 carbon atoms or a fluorinated alkyl group having 1 to 3 carbon atoms, and one or both of R 6 and R 7 are 1 to 3 fluorinated alkyl groups.
  • Examples of the alkyl group and the fluorinated alkyl group in the compound (5) include a linear structure and a branched structure, respectively.
  • One or both of R 6 and R 7 is a fluorinated alkyl group having 1 to 3 carbon atoms. By making one or both of R 6 and R 7 a fluorinated alkyl group having 1 to 3 carbon atoms, the solubility of the lithium salt in the non-aqueous electrolyte and the flame retardancy are excellent.
  • R 6 and R 7 in the compound (5) may be the same or different.
  • the compound (5) is preferably a compound in which both R 6 and R 7 are fluorinated alkyl groups having 1 to 3 carbon atoms from the viewpoint of viscosity, boiling point, or availability of the compound.
  • R 6 and R 7 are preferably CF 3 CH 2 — or CHF 2 CF 2 CH 2 —.
  • the total number of carbon atoms in the compound (5) is preferably 4 to 10 and more preferably 4 to 7 from the viewpoint that if the amount is too small, the boiling point is too low and if the amount is too large, the viscosity becomes high.
  • the molecular weight of the compound (5) is preferably from 180 to 400, more preferably from 200 to 350, particularly preferably from 210 to 300 from the viewpoint that if the molecular weight is too small, the boiling point is too low, and if it is too large, the viscosity increases. From the point which is excellent in a flame retardance, 25 mass% or more is preferable and, as for the fluorine content in a compound (5), 30 mass% or more is more preferable. Moreover, since the affinity of lithium salt will fall and phase separation will become easy when there is too much, 60 mass% or less is preferable and 50 mass% or less is more preferable.
  • the compound (5) include bis (2,2,2-trifluoroethyl) carbonate and bis (2,2,3,3-tetrafluoropropyl) carbonate.
  • Bis (2,2,2-trifluoroethyl) carbonate is preferred from the viewpoint of battery performance such as viscosity, availability, and output characteristics.
  • the fluorine-containing solvent (A) may contain a fluorine-containing alkane compound as a fluorine-containing solvent other than the fluorine-containing ether compound, the fluorine-containing chain carboxylic acid ester compound, and the fluorine-containing chain carbonate compound.
  • a fluorine-containing alkane compound as a fluorine-containing solvent other than the fluorine-containing ether compound, the fluorine-containing chain carboxylic acid ester compound, and the fluorine-containing chain carbonate compound.
  • the fluorine-containing alkane compound is preferably a fluorine-containing alkane compound having 4 to 12 carbon atoms. If the fluorine-containing alkane compound has 4 or more carbon atoms, the vapor pressure of the non-aqueous electrolyte is lowered. If the fluorine-containing alkane compound has 12 or less carbon atoms, the solubility of the lithium salt is good.
  • the fluorine content in the fluorine-containing alkane compound is preferably 50 to 80% by mass. If the fluorine content in the fluorine-containing alkane compound is 50% by mass or more, the flame retardancy is excellent. If the fluorine content in the fluorine-containing alkane compound is 80% by mass or less, the solubility of the lithium salt is easily maintained.
  • fluorinated alkane compound a compound having a linear structure is preferable, and nC 4 F 9 CH 2 CH 3 , nC 6 F 13 CH 2 CH 3 , nC 6 F 13 H, nC 8 F 17 H, and the like.
  • a fluorine-containing alkane compound may be used individually by 1 type, and may be used in combination of 2 or more type.
  • Cyclic carboxylic acid ester compound (B) When the liquid composition contains the cyclic carboxylic acid ester compound, the lithium salt is uniformly dissolved in the fluorine-containing solvent (A). In addition, the inclusion of the cyclic carboxylic acid ester compound (B) makes it difficult for the non-aqueous electrolyte and the electrode to react, and thermal runaway in the secondary battery is less likely to occur.
  • a cyclic carboxylic acid ester compound (B) may be used individually by 1 type, and may be used in combination of 2 or more type.
  • cyclic carboxylic acid ester compound (B) a saturated cyclic carboxylic acid ester compound having no carbon-carbon unsaturated bond in the molecule is preferable from the viewpoint of stability to redox reaction.
  • the ring structure in the cyclic carboxylic acid ester compound (B) is preferably a 4- to 10-membered ring, more preferably a 4- to 7-membered ring, further preferably a 5- to 6-membered ring from the viewpoint of easy availability, and particularly a 5-membered ring. preferable.
  • the ring structure of the cyclic carboxylic acid ester compound (B) is preferably a ring structure having one ester bond from the viewpoint of viscosity and stability to redox reaction.
  • the cyclic carboxylic acid ester compound (B) may be a compound in which one or more hydrogen atoms of the alkylene group are substituted with a substituent.
  • the substituent include a fluorine atom, a chlorine atom, an alkyl group, and a fluorinated alkyl group.
  • the alkyl group preferably has 1 to 2 carbon atoms
  • the fluorinated alkyl group preferably has 1 to 2 carbon atoms.
  • the cyclic carboxylic acid ester compound (B) preferably contains the following compound (6) from the viewpoints of stability to redox reaction, structural stability, and viscosity, and more preferably comprises only the compound (6). preferable.
  • a compound (6) may be used individually by 1 type, and may be used in combination of 2 or more type.
  • R 8 to R 13 are each independently a hydrogen atom, a fluorine atom, a chlorine atom, an alkyl group having 1 to 2 carbon atoms, a fluorinated alkyl group having 1 to 2 carbon atoms, or a carbon number having an etheric oxygen atom. 2 to 3 alkyl groups, and q is an integer of 0 to 3.
  • R 8 to R 13 may be the same or different.
  • R 8 to R 13 are preferably a hydrogen atom, a methyl group, or a fluorine atom, more preferably a hydrogen atom or a methyl group, from the viewpoints of stability to redox reaction, viscosity, and availability of the compound.
  • q is preferably 1 to 2 and more preferably 1 from the viewpoint of viscosity and availability of the compound.
  • Compound (6) includes cyclic ester compounds such as ⁇ -butyrolactone, ⁇ -valerolactone, ⁇ -hexanolactone, ⁇ -valerolactone, and ⁇ -caprolactone, and carbon atoms forming the ring of the cyclic ester compound.
  • cyclic ester compounds such as ⁇ -butyrolactone, ⁇ -valerolactone, ⁇ -hexanolactone, ⁇ -valerolactone, and ⁇ -caprolactone
  • carbon atoms forming the ring of the cyclic ester compound or an alkyl group having 2 to 3 carbon atoms in which at least one hydrogen atom has a fluorine atom, a chlorine atom, an alkyl group having 1 to 2 carbon atoms, a fluorinated alkyl group having 1 to 2 carbon atoms, or an etheric oxygen atom
  • the compound substituted by is mentioned.
  • At least one selected from the group consisting of ⁇ -butyrolactone, ⁇ -valerolactone and ⁇ -caprolactone is preferable, and ⁇ -butyrolactone is particularly preferable because it is easily available and has a high effect of suppressing thermal runaway.
  • the non-aqueous electrolyte contains battery characteristics (cycle characteristics, rate characteristics, initial charge / discharge) It becomes a non-aqueous electrolyte excellent in efficiency.
  • the saturated cyclic carbonate compound (C) having no fluorine atom may be used alone or in combination of two or more.
  • the saturated cyclic carbonate compound (C) having no fluorine atom preferably contains the following compound (7) from the viewpoint of battery characteristics (cycle characteristics, rate characteristics, initial charge / discharge efficiency), and consists only of the compound (7). It is more preferable.
  • a compound (7) may be used individually by 1 type, and may be used in combination of 2 or more type.
  • R 14 to R 17 are each independently a hydrogen atom or an alkyl group having 1 to 6 carbon atoms.
  • Examples of the alkyl group in the compound (7) include a linear structure and a branched structure.
  • R 14 to R 17 may be the same or different.
  • R 14 to R 17 are preferably a hydrogen atom, a methyl group, or an ethyl group, and more preferably a hydrogen atom or a methyl group, from the viewpoint of battery characteristics (cycle characteristics, rate characteristics, initial charge / discharge efficiency).
  • Specific examples of the compound (7) include ethylene carbonate, propylene carbonate, butylene carbonate and the like. From the viewpoint of battery characteristics (cycle characteristics, rate characteristics, initial charge / discharge efficiency), ethylene carbonate is preferred.
  • the nonaqueous electrolytic solution is a lithium salt, a fluorine-containing solvent (A), a cyclic carboxylic acid ester compound (B), and a saturated cyclic carbonate compound having no fluorine atom (as required) within a range not impairing the effects of the present invention.
  • a fluorine-containing solvent A
  • B cyclic carboxylic acid ester compound
  • a saturated cyclic carbonate compound having no fluorine atom (as required) within a range not impairing the effects of the present invention.
  • Other compounds other solvents, additives, etc.
  • the nonaqueous electrolytic solution may contain a solvent other than the fluorine-containing solvent (A), the cyclic carboxylic acid ester compound (B), and the saturated cyclic carbonate compound (C) having no fluorine atom.
  • a solvent other than the fluorine-containing solvent (A), the cyclic carboxylic acid ester compound (B), and the saturated cyclic carbonate compound (C) having no fluorine atom examples include fluorine-containing saturated cyclic carbonate compounds, saturated chain carbonate compounds having no fluorine atom, and saturated cyclic sulfone compounds.
  • fluorine-containing saturated cyclic carbonate compound examples include 4-fluoro-1,3-dioxolane-2-one, 4-trifluoromethyl-1,3-dioxolane-2-one, and 4,5-difluoro-1,3-dioxolane. -2-one and the like.
  • saturated chain carbonate compound having no fluorine atom examples include dimethyl carbonate, ethyl methyl carbonate, diethyl carbonate and the like.
  • saturated cyclic sulfone compound examples include sulfolane and 3-methylsulfolane.
  • the non-aqueous electrolyte may contain conventionally known additives as necessary.
  • the additive include an overcharge inhibitor, a dehydrating agent, a deoxidizing agent, a property improving aid, and a surfactant.
  • Overcharge prevention agent aromatic compounds (biphenyl, alkylbiphenyl, terphenyl, terphenyl partially hydrogenated, cyclohexylbenzene, t-butylbenzene, t-amylbenzene, diphenyl ether, dibenzofuran, etc.), aromatic compounds Partially fluorinated products (2-fluorobiphenyl, o-cyclohexylfluorobenzene, p-cyclohexylfluorobenzene, etc.), fluorine-containing anisole compounds (2,4-difluoroanisole, 2,5-difluoroanisole, 2,6-difluoroaniol, etc.) ).
  • An overcharge inhibitor may be used individually by 1 type, and may use 2 or more types together.
  • Dehydrating agent examples include molecular sieves, mirabilite, magnesium sulfate, calcium hydride, sodium hydride, potassium hydride, lithium aluminum hydride and the like.
  • the liquid composition or other solvent used for the non-aqueous electrolyte those obtained by rectification after dehydration with a dehydrating agent are preferable. Moreover, what performed only the dehydration by the said dehydrating agent without performing rectification may be used.
  • the characteristic improving aid is for improving capacity maintenance characteristics and cycle characteristics after high temperature storage.
  • Examples of the property improving aid include unsaturated cyclic carbonate compounds (dimethyl vinylene carbonate, vinylene carbonate, vinyl ethylene carbonate, 4-acetylin-1,3-dioxolan-2-one, 3-methyl-4-vinylethylene carbonate, 4,5-divinylethylene carbonate, 4,5-bis (2-methylvinyl) ethylene carbonate, etc.), sulfur-containing compounds (ethylene sulfite, 1,3-propane sultone, 1,4-butane sultone, methyl methanesulfonate, Busulfan, sulfolene, dimethylsulfone, dibutyldisulfide, dicyclohexyldisulfide, tetramethylthiuram monosulfide, N, N-dimethylmethanesulfonamide, N, N-diethylmethanesulfonamide,
  • the surfactant assists the impregnation of the non-aqueous electrolyte into the electrode mixture or separator.
  • any of cationic surfactants, anionic surfactants, nonionic surfactants and amphoteric surfactants may be used.
  • Anionic surfactants are easily available and have a high surfactant effect. Agents are preferred.
  • As the surfactant a fluorine-containing surfactant is preferable from the viewpoint of high oxidation resistance and good cycle characteristics and rate characteristics.
  • Surfactant may be used individually by 1 type and may use 2 or more types together.
  • [Ratio of each component] (Ratio of lithium salt) 5 mass% is preferable, as for the lower limit of the ratio of the mass of lithium salt with respect to the total mass of nonaqueous electrolyte solution, 7 mass% is more preferable, and 8 mass% is further more preferable.
  • the upper limit of the ratio of the mass of the lithium salt to the total mass of the non-aqueous electrolyte is preferably 25% by mass, more preferably 20% by mass, and even more preferably 17% by mass. If the ratio of lithium salt is more than the said lower limit, the ionic conductivity of a non-aqueous electrolyte will become high. If the proportion of the lithium salt is not more than the above upper limit value, the lithium salt is easily dissolved uniformly in the liquid composition, and the lithium salt does not precipitate even under low temperature conditions.
  • the lower limit of the ratio of the number of moles of the compound (1) to the total number of moles of the lithium salt is preferably 0.05 mol%, more preferably 0.1 mol%, still more preferably 0.5 mol%, and particularly preferably 1 mol%.
  • the upper limit of the ratio of the number of moles of the compound (1) to the total number of moles of the lithium salt is preferably 95 mol%, more preferably 80 mol%, further preferably 60 mol%, and particularly preferably 40 mol%.
  • the lower limit value of the ratio of the number of moles of LiPF 6 to the total number of moles of lithium salt is preferably 5 mol%, more preferably 20 mol%, further preferably 40 mol%, and more preferably 60 mol%. Is particularly preferred.
  • the upper limit of the ratio of the number of moles of LiPF 6 to the total number of moles of lithium salt is preferably 99.95 mol%, more preferably 99.9 mol%, further preferably 99.5 mol%, and particularly preferably 99 mol%.
  • the proportion of LiPF 6 is more than the lower limit, easily obtained high superior practicality in ionic conductivity non-aqueous electrolyte. If the ratio of LiPF 6 is less than or equal to the above upper limit value, a nonaqueous electrolytic solution excellent in battery characteristics such as cycle characteristics and rate characteristics can be easily obtained by relatively increasing the content of the compound (1).
  • the lower limit value of the ratio of the total number of moles of the compound (1) and LiPF 6 to the total number of moles of the lithium salt is preferably 50 mol%, and more preferably 80 mol%.
  • the upper limit of the ratio of the total number of moles of the compound (1) and LiPF 6 with respect to the total number of moles of the lithium salt is 100 mol%.
  • the lower limit of the ratio of the mass of the compound (1) to the total mass of the nonaqueous electrolytic solution is preferably 0.01% by mass, more preferably 0.02% by mass, further preferably 0.1% by mass, Mass% is particularly preferred. 10 mass% is preferable, as for the upper limit of the ratio of the mass of the compound (1) with respect to the total mass of nonaqueous electrolyte solution, 8 mass% is more preferable, and 5 mass% is further more preferable. If the ratio of compound (1) is more than the said lower limit, it will become easy to obtain the nonaqueous electrolyte solution excellent in battery characteristics, such as a cycle characteristic and a rate characteristic. If the ratio of the compound (1) is not less than the above upper limit value, the lithium salt is easily dissolved uniformly in the liquid composition, and the lithium salt does not precipitate even at low temperature conditions.
  • the lower limit of the ratio of the mass of the fluorinated solvent (A) to the total mass of the nonaqueous electrolytic solution is preferably 30% by mass, more preferably 45% by mass, further preferably 50% by mass, and particularly preferably 55% by mass.
  • the upper limit of the ratio of the mass of the fluorinated solvent (A) to the total mass of the nonaqueous electrolytic solution is preferably 80% by mass, more preferably 75% by mass, further preferably 73% by mass, and particularly preferably 70% by mass.
  • the non-aqueous electrolyte is excellent in flame retardancy, has low positive electrode reactivity and negative electrode reactivity, hardly causes thermal runaway, and has high high voltage resistance.
  • the ratio of the fluorine-containing solvent (A) is not more than the upper limit value, the lithium salt is easily dissolved uniformly, and the lithium salt does not easily precipitate at a low temperature, so that the ionic conductivity is hardly lowered.
  • the lower limit of the ratio of the mass of the fluorinated solvent (A) to the total mass of the liquid composition is preferably 45 mass%, more preferably 50 mass%, further preferably 55 mass%, particularly preferably 60 mass%.
  • the upper limit of the ratio of the mass of the fluorinated solvent (A) to the total mass of the liquid composition is preferably 90% by mass, more preferably 85% by mass, further preferably 80% by mass, and particularly preferably 75% by mass. If the proportion of the fluorinated solvent (A) is not less than the lower limit, the non-aqueous electrolyte is excellent in flame retardancy, has low positive electrode reactivity and negative electrode reactivity, hardly causes thermal runaway, and has high high voltage resistance. Have If the ratio of the fluorine-containing solvent (A) is not more than the upper limit value, the lithium salt is easily dissolved uniformly, and the lithium salt does not easily precipitate at a low temperature, so that the ionic conductivity is hardly lowered.
  • the lower limit of the ratio of the mass of the fluorinated ether compound to the total mass of the fluorinated solvent (A) is preferably 25 mass%, more preferably 30 mass%. , 50% by mass is more preferable, 60% by mass is further preferable, and 70% by mass is particularly preferable.
  • the upper limit of the ratio of the mass of the fluorinated ether compound to the total mass of the fluorinated solvent (A) is 100% by mass.
  • the fluorine-containing solvent (A) is particularly preferably composed only of a fluorine-containing ether compound from the viewpoints of the solubility of the lithium salt, the flame retardance of the non-aqueous electrolyte, and the ionic conductivity.
  • the lower limit of the ratio of the mass of the fluorine-containing ether compound to the total mass of the non-aqueous electrolyte is preferably 10% by mass, and 20% by mass. Is more preferable, 30% by mass is further preferable, 45% by mass is further preferable, and 50% by mass is particularly preferable.
  • the upper limit of the ratio of the mass of the fluorine-containing ether compound to the total mass of the nonaqueous electrolytic solution is preferably 80% by mass, more preferably 75% by mass, further preferably 73% by mass, and particularly preferably 70% by mass.
  • the lower limit of the ratio of the mass of the fluorinated chain carboxylic acid ester compound to the total mass of the fluorinated solvent (A) is 0.01 mass. % Is preferred.
  • the upper limit of the ratio of the mass of the fluorinated chain carboxylic acid ester compound to the total mass of the fluorinated solvent (A) is preferably 50 mass%, more preferably 40 mass%, further preferably 30 mass%, more preferably 20 mass%. Is particularly preferred.
  • the lower limit of the ratio of the mass of the fluorine-containing chain carbonate compound to the total mass of the fluorine-containing solvent (A) is preferably 0.01% by mass.
  • the upper limit of the ratio of the mass of the fluorinated chain carbonate compound to the total mass of the fluorinated solvent (A) is preferably 50 mass%, more preferably 40 mass%, further preferably 30 mass%, particularly preferably 20 mass%. preferable.
  • the ratio of the mass of the fluorinated alkane compound to the total mass of the nonaqueous electrolytic solution is preferably from 0.01 to 5 mass%.
  • the ratio of the fluorine-containing alkane compound is 0.01% by mass or more, the vapor pressure is low and the flame retardancy is excellent.
  • the proportion of the fluorine-containing alkane compound is 5% by mass or less, the solubility of the lithium salt is easily maintained.
  • the fluorine-containing solvent (A) is used in combination with a fluorine-containing ether compound and at least one selected from a fluorine-containing chain carboxylic acid ester compound, a fluorine-containing chain carbonate compound and a fluorine-containing alkane compound, the ratio thereof is as follows: It can be decided arbitrarily.
  • the lower limit of the ratio of the mass of the cyclic carboxylic acid ester compound (B) to the total mass of the non-aqueous electrolyte is preferably 4% by mass, more preferably 7% by mass, still more preferably 10% by mass, and particularly preferably 15% by mass. preferable.
  • the upper limit of the ratio of the mass of the cyclic carboxylic acid ester compound (B) to the total mass of the nonaqueous electrolytic solution is preferably 60% by mass, more preferably 45% by mass, still more preferably 40% by mass, and particularly preferably 35% by mass. preferable.
  • the ratio of the cyclic carboxylic acid ester compound (B) is equal to or higher than the lower limit, the non-aqueous electrolyte uniformly dissolves the lithium salt, the reactivity between the non-aqueous electrolyte and the electrode is small, and thermal runaway occurs. Hateful. If the ratio of the cyclic carboxylic acid ester compound (B) is not more than the upper limit value, the non-aqueous electrolyte is excellent in flame retardancy.
  • the lower limit of the ratio N B / N Li of the total number of moles N B of the cyclic carboxylic acid ester compound (B) to the total number of moles N Li of lithium atoms derived from the lithium salt contained in the non-aqueous electrolyte is 1. 5 is preferable, 2 is more preferable, 2.5 is more preferable, and 3 is particularly preferable.
  • the upper limit value of N B / N Li is preferably 5.5, more preferably 5, more preferably 4.5, and particularly preferably 4.2.
  • N B / N Li is equal to or greater than the lower limit, the non-aqueous electrolyte uniformly dissolves the lithium salt, the reactivity between the non-aqueous electrolyte and the electrode is small, and thermal runaway hardly occurs.
  • N B / N Li is not more than the above upper limit value, the non-aqueous electrolyte is excellent in flame retardancy.
  • the ratio of the mass of the saturated cyclic carbonate compound (C) having no fluorine atom to the total mass of the nonaqueous electrolytic solution is 0.01 to 20% by mass.
  • the lower limit of the mass of the saturated cyclic carbonate compound (C) having no fluorine atom relative to the total mass of the nonaqueous electrolytic solution is preferably 0.05% by mass, more preferably 0.1% by mass, and 0.5% by mass. Particularly preferred.
  • the upper limit of the ratio of the mass of the saturated cyclic carbonate compound (C) having no fluorine atom to the total mass of the nonaqueous electrolytic solution is preferably 15% by mass, more preferably 13% by mass, and particularly preferably 10% by mass. If the ratio of the saturated cyclic carbonate compound (C) having no fluorine atom is not less than the lower limit value, a nonaqueous electrolytic solution excellent in battery characteristics (cycle characteristics, rate characteristics, initial charge / discharge efficiency) is easily obtained. If the ratio of the saturated cyclic carbonate compound (C) having no fluorine atom is not more than the above upper limit value, the viscosity of the electrolytic solution does not become too high, and the electrolytic solution is excellent in rate characteristics.
  • the upper limit of the ratio of the mass of the other solvent to the total mass of the non-aqueous electrolyte is preferably 30% by mass, more preferably 20% by mass, and further 15% by mass 10% by mass is preferable.
  • the lower limit of the ratio of the mass of the other solvent to the total mass of the non-aqueous electrolyte is 0% by mass. If the ratio of the other solvent is not more than the upper limit value, it is easy to suppress the reaction between the other solvent and the electrode, and a non-aqueous electrolyte solution having excellent stability can be obtained. Moreover, since it is easy to increase content of a fluorine-containing solvent (A), the nonaqueous electrolyte solution excellent in the flame retardance is easy to be obtained.
  • the ratio of the mass of the fluorine-containing saturated cyclic carbonate compound to the total mass of the non-aqueous electrolyte is preferably 0.01 to 20% by mass, and 0.01 to 15 % By mass is more preferable, 0.01 to 10% by mass is further preferable, 0.01 to 5% by mass is further preferable, and 0.01 to 3% by mass is particularly preferable. If the ratio of a fluorine-containing saturated cyclic carbonate compound is below an upper limit, a fluorine-containing saturated cyclic carbonate compound and an electrode will be hard to react, and nonaqueous electrolyte solution is excellent in stability and flame retardance.
  • the ratio of the mass of the saturated chain carbonate compound having no fluorine atom to the total mass of the non-aqueous electrolyte is 0.01 to 30% by mass. Is preferable, and 0.01 to 20% by mass is more preferable. If the ratio of the saturated chain carbonate compound having no fluorine atom is not more than the upper limit value, the saturated chain carbonate compound having no fluorine atom and the electrode are unlikely to react, and the non-aqueous electrolyte is stable and flame retardant. Excellent.
  • the ratio of the mass of the saturated cyclic sulfone compound to the total mass of the nonaqueous electrolytic solution is preferably 0.01 to 20% by mass, more preferably 0.01 to 15% by mass. 0.01 to 10% by mass is more preferable, and 0.01 to 5% by mass is particularly preferable. If the ratio of the saturated cyclic sulfone compound is not more than the above upper limit value, the saturated cyclic sulfone compound and the electrode are unlikely to react with each other, and the non-aqueous electrolyte is excellent in stability and flame retardancy.
  • the ratio of the mass of the overcharge inhibitor to the total mass of the non-aqueous electrolyte is preferably 0.01 to 5% by mass. If the ratio of the non-aqueous electrolyte is equal to or higher than the lower limit, it becomes easier to suppress the secondary battery from bursting and firing due to overcharging, and the secondary battery can be used more stably.
  • the ratio of the mass of the characteristic improving auxiliary to the total mass of the non-aqueous electrolytic solution is preferably 0.01 to 5% by mass.
  • the upper limit of the ratio of the mass of the surfactant to the total mass of the non-aqueous electrolyte is preferably 5% by mass, more preferably 3% by mass, and further 2% by mass preferable.
  • the lower limit of the ratio of the mass of the surfactant to the total mass of the non-aqueous electrolyte is preferably 0.05% by mass.
  • the lithium salt contains the compound (1), and the liquid composition contains the saturated cyclic carbonate compound (C) having no fluorine atom, so that the surface of the electrode active material Therefore, it is estimated that a lithium ion secondary battery excellent in battery characteristics (cycle characteristics, rate characteristics, initial charge / discharge efficiency) can be obtained.
  • the lithium ion secondary battery of the present invention has a positive electrode, a negative electrode, and the non-aqueous electrolyte of the present invention.
  • Examples of the positive electrode include an electrode in which a positive electrode layer containing a positive electrode active material, a conductivity-imparting agent, and a binder is formed on a current collector.
  • the positive electrode active material may be any material that can occlude and release lithium ions.
  • known positive electrode active materials for lithium ion secondary batteries can be employed.
  • positive electrode active materials include lithium-containing transition metal oxides, lithium-containing transition metal composite oxides using two or more transition metals, transition metal oxides, transition metal sulfides, metal oxides, olivine-type metal lithium salts, etc. Is mentioned.
  • a positive electrode active material may be used individually by 1 type, and may use 2 or more types together.
  • lithium-containing transition metal oxide examples include lithium cobalt oxide (LiCoO 2 and the like), lithium nickel oxide (LiNiO 2 and the like), lithium manganese oxide (LiMnO 2 , LiMn 2 O 4 , Li 2 MnO 3 and the like). Can be mentioned.
  • the metal contained in the lithium-containing transition metal composite oxide Al, V, Ti, Cr, Mn, Fe, Co, Li, Ni, Cu, Zn, Mg, Ga, Zr, Si, Yb and the like are preferable.
  • Some of the transition metal atoms that are the main components of these lithium transition metal composite oxides are Al, Ti, V, Cr, Mn, Fe, Co, Li, Ni, Cu, Zn, Mg, Ga, Zr, Si, and Yb.
  • transition metal oxide examples include TiO 2 , MnO 2 , MoO 3 , V 2 O 5 , V 6 O 13 and the like.
  • transition metal sulfide examples include TiS 2 , FeS, and MoS 2 .
  • metal oxide examples include SnO 2 and SiO 2 .
  • Olivine type metal lithium salt Li L M 3 x M 4 y O z F g ( however, M 3 is, Fe (II), Co ( II), Mn (II), Ni (II), V (II) Or Cu (II), M 4 is P or Si, and 0 ⁇ L ⁇ 3, 1 ⁇ x ⁇ 2, 1 ⁇ y ⁇ 3, 4 ⁇ z ⁇ 12, 0 ⁇ g ⁇ 1. ) Or a complex thereof.
  • Examples of the olivine type metal lithium salt include the following.
  • a material in which a substance having a composition different from that of the main constituent of the positive electrode active material is attached to the surface of the positive electrode active material can also be used.
  • Surface adhering substances include oxides (aluminum oxide, silicon oxide, titanium oxide, zirconium oxide, magnesium oxide, calcium oxide, boron oxide, antimony oxide, bismuth oxide, etc.), sulfates (lithium sulfate, sodium sulfate, potassium sulfate, Magnesium sulfate, calcium sulfate, aluminum sulfate, etc.), carbonates (lithium carbonate, calcium carbonate, magnesium carbonate, etc.) and the like.
  • the lower limit of the amount of the surface adhering substance relative to the positive electrode active material is preferably 0.1 mass ppm, more preferably 1 mass ppm, and particularly preferably 10 mass ppm. 20 mass% is preferable, the upper limit of the quantity of the surface adhesion substance with respect to a positive electrode active material is more preferable, 10 mass% is more preferable, and 5 mass% is especially preferable.
  • the surface adhering substance can suppress the oxidation reaction of the nonaqueous electrolytic solution on the surface of the positive electrode active material, and can improve the battery life.
  • lithium-containing transition metal oxides LiCoO 2 , LiNiO 2 , LiMnO 2, etc.
  • LiCoO 2 , LiNiO 2 , LiMnO 2, etc. based on ⁇ -NaCrO 2 structure, spinel from the viewpoint of high discharge voltage and high electrochemical stability.
  • a lithium-containing transition metal oxide (LiMn 2 O 4 or the like) having a mold structure as a base is preferable.
  • Conductivity imparting agent examples include carbon materials, metal substances (such as Al), and conductive oxide powders.
  • binder examples include resin binders (such as polyvinylidene fluoride) and rubber binders (hydrocarbon rubber, fluororubber, etc.).
  • resin binders such as polyvinylidene fluoride
  • rubber binders hydrocarbon rubber, fluororubber, etc.
  • Examples of the current collector include a metal thin film mainly composed of Al or the like.
  • Examples of the negative electrode include an electrode in which a negative electrode layer containing a powdered negative electrode active material, a conductivity-imparting agent, and a binder is formed on a current collector.
  • a negative electrode active material can maintain a shape by itself (for example, when it is a lithium metal thin film), a negative electrode can be formed only with a negative electrode active material.
  • Examples of the negative electrode active material include at least one selected from the group consisting of a lithium metal, a lithium alloy, and a carbon material capable of inserting and extracting lithium ions.
  • Examples of the lithium alloy include a Li—Si alloy, a Li—Al alloy, a Li—Pb alloy, and a Li—Sn alloy.
  • Examples of the carbon material include graphite, coke, and hard carbon.
  • Examples of the current collector include a metal thin film mainly composed of Cu or the like.
  • a separator is interposed between the positive electrode and the negative electrode to prevent a short circuit.
  • the separator include a porous film.
  • a non-aqueous electrolyte is used by impregnating the porous membrane.
  • you may use as a gel electrolyte what impregnated the porous film with the nonaqueous electrolyte solution, and was made to gelatinize.
  • porous film one that is stable with respect to the non-aqueous electrolyte and excellent in liquid retention can be used.
  • a porous film a porous sheet or a nonwoven fabric is preferable. You may use what laminated
  • the material for the porous film include fluororesins (polyvinylidene fluoride, polytetrafluoroethylene, copolymers of ethylene and tetrafluoroethylene, etc.), polyimides, polyolefins (polyethylene, polypropylene, etc.), oxidation resistance, air permeability, Polyolefin is preferable from the viewpoint of availability.
  • an inorganic fine particle layer may be provided on the surface of either or both of the separator and the electrode.
  • the inorganic fine particles include silica, alumina, titania, magnesia and the like.
  • Examples of the material for the battery outer package include nickel-plated iron, stainless steel, aluminum or an alloy thereof, nickel, titanium, a resin material, and a film material.
  • the shape of the lithium ion secondary battery may be selected according to the application, and may be any shape such as a coin shape, a cylindrical shape, a square shape, and a laminate shape. Moreover, the shape of a positive electrode and a negative electrode can be suitably selected according to the shape of a secondary battery.
  • the charging voltage of the lithium ion secondary battery of the present invention is preferably 4.25 V or more, more preferably 4.30 V or more, further preferably 4.35 V or more, and particularly preferably 4.40 V or more in terms of the potential with respect to lithium.
  • the lithium ion secondary battery of the present invention described above is excellent in battery characteristics (cycle characteristics, rate characteristics, initial charge / discharge efficiency) because the non-aqueous electrolyte of the present invention is used.
  • Examples 1 to 9 are examples, and examples 10 to 14 are comparative examples.
  • a tetrafluoroethylene-propylene rubber aqueous dispersion latex binder (0.26 g) adjusted to a solid content concentration of 34% by mass was added and stirred for 1 minute at a rotational speed of 2000 rpm using the stirrer to form a slurry for electrode coating. Obtained.
  • the slurry is coated on a copper foil having a thickness of 20 ⁇ m to a thickness of 210 ⁇ m, dried and then pressed with a roll press to a porosity of 15 to 25%, and then punched into a circle with a diameter of 16 mm for evaluation.
  • LiCoO 2 manufactured by AGC Seimi Chemical Co., Ltd., 32.0 g
  • carbon black manufactured by Denki Kagaku Kogyo Co., Ltd., 0.8 g
  • a revolving revolving stirrer manufactured by Shinky Co., Ltd., Awatori Netaro AR-E310
  • the step of stirring for 30 seconds at 2000 rpm was performed three times.
  • the step of adding N-methyl-2-pyrrolidone (6.0 g) and stirring with the stirrer at a rotation speed of 2000 rpm for 5 minutes was performed 4 times.
  • the step of adding N-methyl-2-pyrrolidone (0.8 g) and stirring for 3 minutes at 2000 rpm using the stirrer was performed three times.
  • a solution of polyvinylidene fluoride in N-methyl-2-pyrrolidone (11% by mass, 7.45 g) was added and stirred for 1 minute at a rotational speed of 2000 rpm using the stirrer to obtain a slurry.
  • the slurry is applied to a thickness of 180 ⁇ m on an aluminum foil having a thickness of 20 ⁇ m, dried, pressed with a roll press machine so that the porosity is 35 to 40%, and then punched into a circle with a diameter of 15 mm.
  • An evaluation electrode positive electrode
  • a cell comprising a LiCoO 2 electrode-graphite electrode, with a positive electrode and a negative electrode facing each other, a polyolefin microporous membrane as an electrode separator for evaluation existing between each electrode, a non-aqueous electrolyte (0.02 mL) added thereto was made.
  • the battery was charged to 4.35V with a current corresponding to 0.2C, and further charged until the current value reached a current corresponding to 0.02C at the charge lower limit voltage. Then, it discharged to 3.0V with the electric current corresponding to 0.2C. In 5 cycles, the battery was charged to 4.35 V with a current corresponding to 0.5 C, and further charged until the current value reached a current corresponding to 0.02 C at the charge lower limit voltage. Thereafter, the battery was discharged to 3.0 V with a current corresponding to 1.0 C.
  • the rate test was conducted for 6 to 11 cycles. Charging was performed until a current corresponding to 0.02C was reached at a charging lower limit voltage after charging to 4.35V with a current corresponding to 0.5C. The discharge was performed at 0.1 C for 6 cycles, 0.2 C for 7 cycles, 0.5 C for 8 cycles, 1.0 C for 9 cycles, and 3.0 V at a current corresponding to 2.0 C for 10 cycles. As an evaluation of the rate characteristics, the discharge capacity maintenance rate at 1.0 C discharge relative to the discharge capacity at 0.1 C discharge was measured.
  • the battery was charged to 4.35 V at a current corresponding to 0.5 C, and further charged until the current value reached a current corresponding to 0.02 C at the charge lower limit voltage. Then, it discharged to 3.0V with the electric current corresponding to 0.5C.
  • the cycle characteristics were evaluated based on the discharge capacity retention rate of 50 cycles and 100 cycles with respect to the discharge capacity of the 12th cycle.
  • LiPF LiPF 6
  • LiFOB Compound (1-1).
  • DMC dimethyl carbonate
  • EMC ethyl methyl carbonate
  • VC vinylene carbonate
  • FEC 4-fluoro-1,3-dioxolan-2-one.
  • Example 1 After diffusing LPF (0.15 g) and LiFOB (0.03 g) which are lithium salts into AE3000 (0.71 g) which is a fluorine-containing ether solvent (A), the cyclic carboxylic acid ester compound (B) is obtained. GBL (0.34 g), EC (0.03 g) which is a saturated cyclic carbonate compound (C) having no fluorine atom, and DMC (0.22 g) which is another solvent were mixed to obtain a non-aqueous electrolyte solution 1. . A cell was prepared using Nonaqueous Electrolytic Solution 1 (20 ⁇ L), and a charge / discharge test was performed. The results are shown in Table 1.
  • Nonaqueous electrolytes 2 to 14 were obtained in the same manner as in Example 1 except that the composition of each compound such as lithium salt was changed as shown in Tables 1 and 2.
  • Tables 1 and 2 the content (mass%) of each component is shown as a percentage of the content of each component with respect to the total content (mass) of each component contained in the non-aqueous electrolyte.
  • the cell was produced like Example 1 and the charge / discharge test was done. The results are shown in Tables 1 and 2.
  • Examples 1 to 9 in which LiFOB as the compound (1) and EC as the saturated cyclic carbonate compound (C) having no fluorine atom are used in a specific amount do not have a fluorine atom.
  • Examples 13 and 12 containing no saturated cyclic carbonate compound (C), 14 containing no compound (1), 11 containing no compound (1) and no saturated cyclic carbonate compound (C) having no fluorine atom In comparison, the initial charge / discharge efficiency, cycle characteristics, and rate characteristics were all improved.
  • the nonaqueous electrolytic solution of the present invention is useful as a nonaqueous electrolytic solution for a lithium ion secondary battery.
  • the lithium ion secondary battery of the present invention includes a mobile phone, a portable game machine, a digital camera, a digital video camera, an electric tool, a notebook computer, a portable information terminal, a portable music player, an electric vehicle, a hybrid vehicle, a train, an aircraft, an artificial It can be applied to various uses such as satellites, submarines, ships, uninterruptible power supplies, robots, and power storage systems.
  • the lithium ion secondary battery of the present invention is particularly effective as a large secondary battery for electric vehicles, hybrid vehicles, trains, airplanes, artificial satellites, submarines, ships, uninterruptible power supplies, robots, power storage systems, and the like. is there. It should be noted that the entire contents of the specification, claims, and abstract of Japanese Patent Application No. 2014-086255 filed on April 18, 2014 are incorporated herein as the disclosure of the specification of the present invention. Is.

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Abstract

　La présente invention concerne une solution électrolytique non aqueuse pour batteries rechargeables, qui peut être utilisée pour obtenir une batterie rechargeable au lithium-ion présentant d'excellentes caractéristiques de batterie (caractéristiques de cycle, caractéristiques de régime, et efficacité de charge et décharge initiale), et une batterie rechargeable au lithium-ion utilisant la solution électrolytique non aqueuse pour batteries rechargeables. La solution électrolytique non aqueuse pour batteries rechargeables contient : un sel de lithium comprenant un composé représenté par la formule (1) (dans laquelle M est B ou P, R1 est un groupe alkylène en C1-10, X est un atome d'halogène, n vaut 0-4, m vaut 0 ou 1, et p vaut 1 ou 2) ; un solvant contenant du fluor spécifique (A) ; un composé ester d'acide carboxylique cyclique (B) ; et un composé carbonate cyclique saturé (C) qui ne contient aucun atome de fluor. La proportion de la masse du composé carbonate cyclique saturé (C) qui ne contient aucun atome de fluor relativement à la masse totale de la solution électrolytique non aqueuse est de 0,01 à 20 % en masse.
PCT/JP2015/061262 2014-04-18 2015-04-10 Solution électrolytique non aqueuse pour batterie rechargeable, et batterie rechargeable au lithium-ion WO2015159824A1 (fr)

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JP2014086255A JP2017107639A (ja) 2014-04-18 2014-04-18 二次電池用非水電解液およびリチウムイオン二次電池
JP2014-086255 2014-04-18

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CN108475810A (zh) * 2016-01-07 2018-08-31 罗伯特·博世有限公司 电解质和含有该电解质的电池组单元
CN110931863A (zh) * 2019-11-12 2020-03-27 深圳市比克动力电池有限公司 电池电解液用添加剂、锂离子电池电解液、锂离子电池
CN113646944A (zh) * 2019-03-21 2021-11-12 株式会社Lg新能源 锂二次电池用非水电解质溶液以及包含其的锂二次电池

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JP2007250288A (ja) * 2006-03-15 2007-09-27 Sanyo Electric Co Ltd 非水電解質二次電池の製造方法
JP2010086914A (ja) * 2008-10-02 2010-04-15 Daikin Ind Ltd 非水電解液
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WO2013146359A1 (fr) * 2012-03-27 2013-10-03 旭硝子株式会社 Solution d'électrolyte non aqueux pour batteries secondaires et batterie secondaire au lithium-ion
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JP2006127933A (ja) * 2004-10-29 2006-05-18 Sanyo Electric Co Ltd 非水電解液及びこれを用いた非水電解質二次電池
JP2007250288A (ja) * 2006-03-15 2007-09-27 Sanyo Electric Co Ltd 非水電解質二次電池の製造方法
JP2010086914A (ja) * 2008-10-02 2010-04-15 Daikin Ind Ltd 非水電解液
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Publication number Priority date Publication date Assignee Title
CN108475810A (zh) * 2016-01-07 2018-08-31 罗伯特·博世有限公司 电解质和含有该电解质的电池组单元
CN113646944A (zh) * 2019-03-21 2021-11-12 株式会社Lg新能源 锂二次电池用非水电解质溶液以及包含其的锂二次电池
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CN113646944B (zh) * 2019-03-21 2024-05-24 株式会社Lg新能源 锂二次电池用非水电解质溶液以及包含其的锂二次电池
CN110931863A (zh) * 2019-11-12 2020-03-27 深圳市比克动力电池有限公司 电池电解液用添加剂、锂离子电池电解液、锂离子电池

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