WO2022032583A1 - 电解液和包含电解液的电化学装置及电子装置 - Google Patents

电解液和包含电解液的电化学装置及电子装置 Download PDF

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WO2022032583A1
WO2022032583A1 PCT/CN2020/108961 CN2020108961W WO2022032583A1 WO 2022032583 A1 WO2022032583 A1 WO 2022032583A1 CN 2020108961 W CN2020108961 W CN 2020108961W WO 2022032583 A1 WO2022032583 A1 WO 2022032583A1
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electrolyte
substituted
additive
unsubstituted
lithium
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PCT/CN2020/108961
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English (en)
French (fr)
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刘建禹
管明明
郑建明
刘建
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宁德新能源科技有限公司
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Priority to CN202080028881.1A priority Critical patent/CN113767500B/zh
Priority to PCT/CN2020/108961 priority patent/WO2022032583A1/zh
Publication of WO2022032583A1 publication Critical patent/WO2022032583A1/zh
Priority to US18/103,170 priority patent/US20230178807A1/en

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • 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
    • H01M10/0561—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of inorganic materials only
    • H01M10/0563—Liquid materials, e.g. for Li-SOCl2 cells
    • 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
    • H01M10/0567—Liquid materials characterised by the additives
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
    • H01M10/0564—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of organic materials only
    • H01M10/0566—Liquid materials
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
    • H01M10/0564—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of organic materials only
    • H01M10/0566—Liquid materials
    • H01M10/0568—Liquid materials characterised by the solutes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
    • H01M10/0564—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of organic materials only
    • H01M10/0566—Liquid materials
    • H01M10/0569—Liquid materials characterised by the solvents
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • H01M4/628—Inhibitors, e.g. gassing inhibitors, corrosion inhibitors
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
    • H01M2004/028—Positive electrodes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M2300/00—Electrolytes
    • H01M2300/0017—Non-aqueous electrolytes
    • H01M2300/0025—Organic electrolyte
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M2300/00—Electrolytes
    • H01M2300/0088—Composites
    • H01M2300/0091—Composites in the form of mixtures
    • 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 application relates to the technical field of energy storage, and in particular, to an electrolyte and an electrochemical device and an electronic device including the electrolyte.
  • lithium-ion batteries have the characteristics of high energy density, no memory effect, and high working voltage, and are gradually replacing traditional Ni-Cd and MH-Ni batteries.
  • people's requirements for lithium-ion batteries continue to increase, and the development of lithium-ion batteries with high safety and long life is one of the main needs of the market.
  • the present application solves at least one problem existing in the related art by providing an electrolyte.
  • the electrolyte provided by the present application can significantly improve the hot box and normal temperature cycle performance of the electrochemical device.
  • the present application also relates to electrochemical devices and electronic devices comprising such electrolytes.
  • the application provides an electrolyte, which comprises a compound of formula I and lithium difluorophosphate,
  • X is selected from substituted or unsubstituted C 1-10 alkyl, substituted or unsubstituted C 2-10 alkenyl, substituted or unsubstituted C 1-5 alkylsulfonyl and Substituted or unsubstituted C 2-5 acyl, when substituted, the substituent is selected from cyano and halogen.
  • the compound of formula I is selected from at least one of N-acetyl caprolactam, N-vinyl caprolactam, N-methyl caprolactam, N-trifluoromethyl caprolactam, or N-methanesulfonyl caprolactam.
  • the content of the compound of formula I is 0.01% to 3% and the content of the lithium difluorophosphate is 0.01% to 1% based on the total weight of the electrolyte.
  • the content of the compound of formula I is a%
  • the content of the lithium difluorophosphate is b%
  • the content of the compound of formula I and lithium difluorophosphate in the electrolyte The ratio a/b is 0.01 to 30.
  • the electrolyte of the present application further comprises at least one of the following compounds:
  • a first additive the first additive comprises a compound of formula II, based on the total weight of the electrolyte, the content of the first additive is 0.01% to 5%:
  • R 1 , R 2 , R 3 are each independently selected from hydrogen, halogen, substituted or unsubstituted C 1-12 alkyl, substituted or unsubstituted C 3-8 cycloalkyl, and substituted or unsubstituted C 3-8 cycloalkyl Unsubstituted C 6-12 aryl, when substituted, the substituent is selected from cyano, nitro, halogen and sulfonyl, and n is an integer from 0 to 7;
  • the second additive comprises the compound of formula III, based on the total weight of the electrolyte, the content of the second additive is 0.1% to 5%:
  • R 4 , R 5 , R 6 are each independently selected from substituted or unsubstituted C 1-12 alkylene, substituted or unsubstituted C 2-12 alkenylene, R 0 -SR group , R 0 -OR group or OR group
  • R 7 is selected from H, fluorine, cyano, substituted or unsubstituted C 1-12 alkyl, substituted or unsubstituted C 2-12 alkenyl , R 0 -SR group, R 0 -OR group or OR group, wherein R 0 and R are each independently selected from substituted or unsubstituted C 1-6 alkylene; when substituted, the substituent selected from halogen, cyano, C 1-6 alkyl, C 2-6 alkenyl and any combination thereof;
  • the third additive comprising a dinitrile or ether dinitrile compound, the content of the third additive being 1% to 8% based on the total weight of the electrolyte;
  • the fourth additive comprising at least one of 1,3-propane sultone, vinyl sulfate or fluoroethylene carbonate, based on the total weight of the electrolyte, the fourth additive
  • the content of additives is 0.1% to 10%.
  • the compound of formula II comprises acrylonitrile, crotonitrile, methacrylonitrile, 3-methylcrotonitrile, 2-pentenenitrile, 2-methyl-2-crotonitrile, or 2- At least one of methyl-2-pentenenitrile;
  • the compound of formula III includes at least one of the following compounds:
  • the dinitrile or ether dinitrile compounds include malononitrile, succinonitrile, glutaronitrile, adiponitrile, pimeliconitrile, suberonitrile, azelonitrile, sebaconitrile, tetramethylsuccinonitrile, 2 - methylglutaronitrile, 2-methyleneglutaronitrile, 2,4-dimethylglutaronitrile, 2,2,4,4-tetramethylglutaronitrile or ethylene glycol bis(propionitrile) at least one of ethers.
  • the electrolyte further comprises an organic solvent and a lithium salt
  • the organic solvent comprises a group selected from the group consisting of ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, ethyl acetate, At least one of methyl propionate, ethyl propionate or propyl propionate
  • the lithium salt includes lithium hexafluorophosphate, lithium bistrifluoromethanesulfonimide, lithium bis(fluorosulfonyl)imide, At least one of lithium fluoroborate, lithium bis-oxalate borate or lithium difluorooxalate borate.
  • the present application also provides an electrochemical device comprising the electrolyte according to the present application.
  • the electrochemical device of the present application further includes a positive electrode comprising:
  • the insulating layer is disposed on the positive electrode current collector, and the insulating layer satisfies at least one of the conditions (a) to (c):
  • the insulating layer includes inorganic particles, and the inorganic particles include aluminum oxide, silicon dioxide, magnesium oxide, titanium oxide, hafnium dioxide, tin oxide, ceria, nickel oxide, zinc oxide, calcium oxide, calcium oxide, at least one of zirconia, yttrium oxide, silicon carbide, boehmite, aluminum hydroxide, magnesium hydroxide, calcium hydroxide or barium sulfate;
  • the insulating layer includes a polymer, and the polymer includes a homopolymer of vinylidene fluoride, a copolymer of vinylidene fluoride, a copolymer of hexafluoropropylene, polystyrene, polyphenylene vinylene, sodium polyvinylidene , at least one of potassium polyvinate, polymethyl methacrylate, polyethylene, polypropylene or polytetrafluoroethylene.
  • the present application also provides an electronic device comprising the electrochemical device according to the present application.
  • the positive electrode comprises a positive electrode current collector (1), a first surface positive electrode active material layer (2), a second surface active material layer (3) and an insulating layer (4).
  • FIG. 2 shows the scanning electron microscope image of the negative electrode copper deposition test.
  • a term may refer to a range of variation less than or equal to ⁇ 10% of the numerical value, such as less than or equal to ⁇ 5%, less than or equal to ⁇ 4%, less than or equal to ⁇ 3%, Less than or equal to ⁇ 2%, less than or equal to ⁇ 1%, less than or equal to ⁇ 0.5%, less than or equal to ⁇ 0.1%, or less than or equal to ⁇ 0.05%.
  • the difference between two values is less than or equal to ⁇ 10% of the mean of the values (eg, less than or equal to ⁇ 5%, less than or equal to ⁇ 4%, less than or equal to ⁇ 3%, less than or equal to ⁇ 2%, less than or equal to ⁇ 1%, less than or equal to ⁇ 0.5%, less than or equal to ⁇ 0.1%, or less than or equal to ⁇ 0.05%), then the two values are considered to be "about" the same.
  • relative terms such as: “central”, “longitudinal”, “lateral”, “front”, “rear”, “right” of”, “left”, “inner”, “outer”, “lower”, “higher”, “horizontal”, “vertical”, “above”, “below” , “above,” “below,” “top,” “bottom,” and terms derived therefrom (eg, “horizontally,” “downward,” “upward,” etc.) should be construed as references Orientation described in the discussion or depicted in the drawings. These relative terms are used for convenience of description only and do not require that the application be constructed or operated in a particular direction.
  • a list of items joined by the terms "one of,” “one of,” “one of,” or other similar terms can mean that any of the listed items one.
  • the phrase “one of A and B” means A only or B only.
  • the phrase “one of A, B, and C” means A only; B only; or C only.
  • Item A may contain a single element or multiple elements.
  • Item B may contain a single element or multiple elements.
  • Item C may contain a single element or multiple elements.
  • a list of items joined by the terms "at least one of,” “at least one of,” “at least one of,” or other similar terms may mean the listed items any combination of .
  • the phrase “at least one of A and B” means A only; B only; or A and B.
  • the phrase "at least one of A, B, and C” means A only; or B only; C only; A and B (excluding C); A and C (excluding B); B and C (excluding A); or all of A, B, and C.
  • Item A may contain a single element or multiple elements.
  • Item B may contain a single element or multiple elements.
  • Item C may contain a single element or multiple elements.
  • a “ Cnm” group refers to a group having “n” to “m” carbon atoms, where “n” and “m” are integers.
  • “C 1-10 “alkyl is an alkyl group having 1 to 10 carbon atoms.
  • alkyl is intended to be a straight chain saturated hydrocarbon structure having from 1 to 20 carbon atoms. "Alkyl” is also contemplated to be a branched or cyclic hydrocarbon structure having 3 to 20 carbon atoms.
  • the alkyl group can be an alkyl group of 1 to 20 carbon atoms, an alkyl group of 1 to 10 carbon atoms, an alkyl group of 1 to 5 carbon atoms, an alkyl group of 5 to 20 carbon atoms, an alkyl group of 5 to 15 carbon atoms An alkyl group of carbon atoms or an alkyl group of 5 to 10 carbon atoms.
  • butyl is meant to include n-butyl, sec-butyl, isobutyl, tert-butyl and cyclobutyl;
  • propyl includes n-propyl, isopropyl and cyclopropyl.
  • alkyl groups include, but are not limited to, methyl, ethyl, n-propyl, isopropyl, cyclopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, cyclobutyl, n-pentyl, isopentyl, neopentyl, cyclopentyl, methylcyclopentyl, ethylcyclopentyl, n-hexyl, isohexyl, cyclohexyl, n-heptyl, octyl, cyclopropyl, cyclobutyl, norbornyl Base et al. Additionally, alkyl groups can be optionally substituted.
  • alkenyl refers to a monovalent unsaturated hydrocarbon group which may be straight or branched and having at least one and usually 1, 2 or 3 carbon-carbon double bonds. Unless otherwise defined, the alkenyl group typically contains from 2 to 20 carbon atoms, for example, it may be alkenyl of 2 to 20 carbon atoms, alkenyl of 6 to 20 carbon atoms, alkenyl of 2 to 10 carbon atoms group or an alkenyl group of 2 to 6 carbon atoms.
  • Representative alkenyl groups include, for example, vinyl, n-propenyl, isopropenyl, n-but-2-enyl, but-3-enyl, n-hex-3-enyl, and the like. Additionally, alkenyl groups may be optionally substituted.
  • alkylene means a divalent saturated alkyl group which may be straight or branched. Unless otherwise defined, the alkylene groups typically contain 1 to 10, 1 to 6, 1 to 4, or 2 to 4 carbon atoms, and include, for example, C2-3 alkylene and C2 -6 alkylene. Representative alkylene groups include, for example, methylene, ethane-1,2-diyl ("ethylene"), propane-1,2-diyl, propane-1,3-diyl, butane -1,4-diyl, pentane-1,5-diyl, etc.
  • ethylene ethane-1,2-diyl
  • propane-1,3-diyl propane-1,3-diyl
  • butane -1,4-diyl pentane-1,5-diyl, etc.
  • alkenylene means a bifunctional group obtained by removing one hydrogen atom from an alkenyl group as defined above.
  • cycloalkyl encompasses cyclic alkyl groups.
  • the cycloalkyl group may be a cycloalkyl group of 2 to 20 carbon atoms, a cycloalkyl group of 6 to 20 carbon atoms, a cycloalkyl group of 2 to 10 carbon atoms, or a cycloalkyl group of 2 to 6 carbon atoms.
  • the cycloalkyl group can be cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, and the like.
  • cycloalkyl groups may be optionally substituted.
  • aryl means a monovalent aromatic hydrocarbon having a single ring (eg, phenyl) or fused rings. Fused ring systems include those that are fully unsaturated (eg, naphthalene) as well as those that are partially unsaturated (eg, 1,2,3,4-tetrahydronaphthalene). Unless otherwise defined, the aryl groups typically contain 6 to 26, 6 to 20, 6 to 15, or 6 to 10 carbon ring atoms and include, for example, C6-10 aryl groups. Representative aryl groups include, for example, phenyl, methylphenyl, propylphenyl, isopropylphenyl, benzyl, and naphth-1-yl, naphth-2-yl, and the like.
  • heterocycle or “heterocyclyl” means a substituted or unsubstituted 5 to 8 membered mono- or bicyclic non-aromatic hydrocarbon in which 1 to 3 carbon atoms are replaced by heteroatoms selected from nitrogen, oxygen or sulfur atoms .
  • heteroatoms selected from nitrogen, oxygen or sulfur atoms .
  • Examples include pyrrolidin-2-yl; pyrrolidin-3-yl; piperidinyl; morpholin-4-yl and the like, which groups may subsequently be substituted.
  • Heteroatom refers to an atom selected from N, O and S.
  • halogen may be F, Cl, Br or I.
  • cyano encompasses organics containing the organic group -CN.
  • the substituents may be selected from the group consisting of halogen, alkyl, alkenyl, aryl and heteroaryl.
  • the application provides an electrolyte, which comprises a compound of formula I and lithium difluorophosphate,
  • X is selected from substituted or unsubstituted C 1-10 alkyl, substituted or unsubstituted C 2-10 alkenyl, substituted or unsubstituted C 1-5 alkylsulfonyl and Substituted or unsubstituted C 2-5 acyl groups, when substituted, the substituents include but are not limited to cyano and halogen and the like.
  • the compound of formula I is selected from at least one of N-acetyl caprolactam, N-vinyl caprolactam, N-methyl caprolactam, N-trifluoromethyl caprolactam, or N-methanesulfonyl caprolactam.
  • the compound of formula I is present in an amount of 0.01% to 3% based on the total weight of the electrolyte.
  • the compound of formula I may be present in an amount of 0.01%, 0.1%, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, or a range between any two of the foregoing values.
  • the content of lithium difluorophosphate is 0.01% to 1% based on the total weight of the electrolyte.
  • the content of lithium difluorophosphate can be 0.01%, 0.1%, 0.2%, 0.3%, 0.4%, 0.49%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, or any of the above The range between two values.
  • the content of the compound of formula I is 0.5% to 2%, and the content of lithium difluorophosphate can be in the range of 0.1% to 0.5%; when the compound of formula I and lithium difluorophosphate When the content is within the above range, the combination thereof can significantly improve the cycle stability and hot box performance of the electrochemical device.
  • the content of the compound of formula I is a%
  • the content of lithium difluorophosphate is b%
  • the content ratio a/b of the compound of formula I to lithium difluorophosphate in the electrolyte is 0.01 to 30.
  • the content ratio a/b of the compound of formula I to lithium difluorophosphate can be 0.01, 0.1, 1, 1.5, 1.6, 1.7, 2, 2.5, 3, 3.3, 3.5, 4, 5, 6, 6.5, 6.6, 6.7, 7, 8, 10, 15, 18, 20, 25, 30, or a range between any two of the above values.
  • the content ratio a/b of the compound of formula I to lithium difluorophosphate in the electrolyte is 1.5 to 10.
  • the mass ratio is within this range, the improvement of the normal temperature cycle performance and the hot box performance can be better taken into account .
  • the inventors of the present application have unexpectedly found that, in addition to improving high temperature storage performance, the compounds of formula I above can also be used to improve the safety performance of electrochemical devices.
  • the protection of the positive and negative electrodes of the battery is more sufficient, which is beneficial to improve the high voltage stability and high temperature stability of the battery, reduce the impedance, and then improve the normal temperature cycle of the electrochemical device. performance and hot box performance of the battery.
  • the electrolyte of the present application further comprises a first additive comprising a compound of formula II:
  • R 1 , R 2 , R 3 are each independently selected from hydrogen, halogen, substituted or unsubstituted C 1-12 alkyl, substituted or unsubstituted C 3-8 cycloalkyl, and substituted or unsubstituted C 3-8 cycloalkyl Unsubstituted C 6-12 aryl, when substituted, the substituent is selected from cyano, nitro, halogen and sulfonyl, and n is an integer from 0 to 7.
  • alkyl, cycloalkyl and aryl have the definitions as defined above; n can be 1, 2, 3, 4, 5, or 6.
  • the compound of Formula II includes acrylonitrile, crotonitrile, methacrylonitrile, 3-methylcrotonitrile, 2-pentenenitrile, 2-methyl-2-crotonitrile, or 2-methyl - At least one of 2 pentenenitrile.
  • the content of the first additive is 0.01% to 5% based on the total weight of the electrolyte, for example, 0.01%, 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 1%, 2%, 3%, 4%, 5%, or a range between any two values above.
  • a protective film can be formed on the negative electrode more effectively, thereby exerting a protective effect on the negative electrode and improving the high temperature stability of the electrochemical device.
  • the electrolyte of the present application further comprises a second additive comprising a compound of formula III:
  • R 4 , R 5 , R 6 are each independently selected from substituted or unsubstituted C 1-12 alkylene, substituted or unsubstituted C 2-12 alkenylene, R 0 -SR group , R 0 -OR group or OR group
  • R 7 is selected from H, fluorine, cyano, substituted or unsubstituted C 1-12 alkyl, substituted or unsubstituted C 2-12 alkenyl , R 0 -SR group, R 0 -OR group or OR group, wherein R 0 and R are each independently selected from substituted or unsubstituted C 1-6 alkylene; when substituted, the substituent Selected from halogen, cyano, C1-6 alkyl, C2-6 alkenyl, and any combination thereof.
  • compounds of formula III include at least one of the following compounds:
  • the content of the second additive is 0.1% to 5% based on the total weight of the electrolyte, for example, it may be 0.1%, 0.5%, 1%, 2%, 3%, 4%, 5%, Or a range between any two of the above values.
  • the content of the compound of formula III is within the above range, the safety performance of the electrochemical device can be better improved.
  • the electrolyte solution of the present application further includes a third additive, and the third additive includes a dinitrile or ether dinitrile compound.
  • the third additive includes malononitrile, succinonitrile, glutaronitrile, adiponitrile, pimeliconitrile, suberonitrile, azelonitrile, sebaconitrile, tetramethylsuccinonitrile, 2 - methylglutaronitrile, 2-methyleneglutaronitrile, 2,4-dimethylglutaronitrile, 2,2,4,4-tetramethylglutaronitrile or ethylene glycol bis(propionitrile) at least one of ethers.
  • the content of the third additive is 1% to 8% based on the total weight of the electrolyte, for example, it may be 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, or a range between any two of the above values.
  • the content of the third additive in the electrolyte is not less than the content of the second additive. In some embodiments, the content of the third additive (dinitrile or ether dinitrile compound) is greater than the content of the second additive (the compound of formula III). When the content of the third additive is not less than the content of the second additive, the third additive can effectively suppress the corrosive effect on the copper foil caused by the compound of formula III.
  • the electrolyte of the present application further comprises a fourth additive selected from 1,3-propane sultone (PS), vinyl sulfate (DTD) or fluoroethylene carbonate (FEC). at least one of.
  • PS 1,3-propane sultone
  • DTD vinyl sulfate
  • FEC fluoroethylene carbonate
  • the content of the fourth additive is 0.1% to 10%, for example, it may be 0.1%, 0.5%, 1%, 2%, 3%, 4%, 5% %, 6%, 7%, 8%, 9%, 10%, or a range between any two values above.
  • the electrolyte further includes an organic solvent and a lithium salt.
  • the organic solvent comprises selected from ethylene carbonate (EC), propylene carbonate (PC), dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), gamma - at least one of butyrolactone (BL), methyl propionate (MP), ethyl acetate (EA), ethyl propionate (EP) or propyl propionate (PP).
  • EC ethylene carbonate
  • PC propylene carbonate
  • DMC dimethyl carbonate
  • DEC diethyl carbonate
  • EMC ethyl methyl carbonate
  • BL butyrolactone
  • MP methyl propionate
  • EA ethyl acetate
  • EP ethyl propionate
  • PP propyl propionate
  • the lithium salt comprises a lithium hexafluorophosphate (LiPF 6 ), lithium bistrifluoromethanesulfonimide (LiTFSI), lithium bis(fluorosulfonyl)imide (LiFSI), lithium tetrafluoroborate (LiBF 4 ) ), at least one of lithium bis-oxalate borate (LiBOB) or lithium difluorooxalate borate (LiDFOB).
  • LiPF 6 lithium hexafluorophosphate
  • LiTFSI lithium bistrifluoromethanesulfonimide
  • LiFSI lithium bis(fluorosulfonyl)imide
  • LiBF 4 lithium tetrafluoroborate
  • LiBOB lithium bis-oxalate borate
  • LiDFOB lithium difluorooxalate borate
  • the present application also provides an electrochemical device comprising the electrolyte according to the present application.
  • the electrochemical devices of the present application include, but are not limited to, lithium-ion batteries.
  • the electrochemical device includes a positive electrode comprising:
  • the width of the gap is less than or equal to 2mm, for example, it can be 0, 0.5mm, 1mm, 1.5mm or 2mm, or any two of the above values range between;
  • the insulating layer includes inorganic particles, and the inorganic particles include aluminum oxide, silicon dioxide, magnesium oxide, titanium oxide, hafnium dioxide, tin oxide, ceria, nickel oxide, zinc oxide, calcium oxide, calcium oxide, at least one of zirconia, yttrium oxide, silicon carbide, boehmite, aluminum hydroxide, magnesium hydroxide, calcium hydroxide or barium sulfate;
  • the insulating layer includes a polymer, and the polymer includes a homopolymer of vinylidene fluoride, a copolymer of vinylidene fluoride, a copolymer of hexafluoropropylene, polystyrene, polyphenylene vinylene, sodium polyvinylidene , at least one of potassium polyvinate, polymethyl methacrylate, polyethylene, polypropylene or polytetrafluoroethylene.
  • the insulating layer satisfies condition (a) above.
  • the positive electrode comprises a positive electrode current collector (1), a first surface positive electrode active material layer (2), a second surface active material layer (3). ) and the insulating layer (4), wherein, in addition to the area covered by the active material layer, the positive electrode current collector also includes an area not covered by the active material layer (also referred to as an empty foil area).
  • the first surface positive active material layer (2) is shorter than the second surface active material layer (3), the insulating layer (4) is located in the empty foil area on the same side of the first surface positive active material layer on the current collector, and the two ends of the insulating layer are connected with each other.
  • the positive electrode generally includes a positive electrode current collector, a positive electrode active material layer, and the like.
  • the aluminum current collector is at a high potential, and it is easy to generate more heat in contact with the electrolyte. Therefore, by setting an insulating layer on the empty foil area, the positive electrode current collector in the positive electrode can be effectively protected.
  • the empty foil area reduces its direct contact with the electrolyte, which is beneficial to reduce heat generation. Combining the positive electrode that satisfies the condition (a) with the electrolyte described in this application is beneficial to improve the overall thermal stability of the battery and further increase the passing temperature of the hot box.
  • the thickness of the insulating layer is 1 ⁇ m-20 ⁇ m, for example, it can be 1 ⁇ m, 2.5 ⁇ m, 5 ⁇ m, 7.5 ⁇ m, 10 ⁇ m, 12 ⁇ m, 14 ⁇ m, 16 ⁇ m, 18 ⁇ m or 20 ⁇ m, or between any two values above range.
  • the specific type of the positive electrode active material is not particularly limited, and can be selected according to needs, specifically, it can be selected from lithium cobalt oxide (LiCoO 2 ), lithium nickel cobalt manganese (NCM), lithium nickel cobalt aluminum (NCA) ) and other ternary materials, at least one of lithium iron phosphate (LiFePO 4 ) or lithium manganate (LiMn 2 O 4 ).
  • the electrochemical device further includes a negative electrode including a negative electrode current collector and a negative electrode active material layer.
  • the specific types of negative electrode active materials are not specifically limited, and can be selected according to requirements.
  • the negative electrode active material is selected from lithium metal, structured lithium metal, natural graphite, artificial graphite, mesophase micro-carbon spheres (abbreviated as MCMB), hard carbon, soft carbon, silicon, silicon-carbon composites, At least one of Li-Sn alloy, Li-Sn-O alloy, Sn, SnO, SnO 2 , spinel structure lithiated TiO 2 -Li 4 Ti 5 O 12 or Li-Al alloy.
  • the electrochemical device further includes an isolation membrane, and the specific types of the isolation membrane materials are not specifically limited, and can be selected according to requirements.
  • the separator can be selected from polyethylene film, polypropylene film, polyvinylidene fluoride film and their multi-layer composite films, and inorganic or organic substances can also be coated on the surface of the separator substrate according to actual needs to enhance the battery's performance. The hardness may improve the adhesion between the separator and the interface of the positive and negative electrodes.
  • the present application also provides an electronic device comprising the electrochemical device according to the present application.
  • the type of the electronic device of the present application is not particularly limited.
  • the electronic devices of the present application may include, but are not limited to, notebook computers, pen input computers, mobile computers, e-book players, portable telephones, portable fax machines, portable copiers, portable printers, Headphones, VCRs, LCD TVs, Portable Cleaners, Portable CD Players, Mini Discs, Transceivers, Electronic Notepads, Calculators, Memory Cards, Portable Recorders, Radios, Backup Power, Motors, Automobiles, motorcycles , Power-assisted bicycles, bicycles, lighting equipment, toys, game consoles, clocks, power tools, flashlights, cameras, large household batteries and lithium-ion capacitors, etc.
  • the lithium ion batteries in the examples and comparative examples were prepared according to the following methods:
  • ethylene carbonate (EC), propylene carbonate (PC), and diethyl carbonate (DEC) were uniformly mixed in a weight ratio of 1:1:1, and lithium hexafluorophosphate (LiPF) was added.
  • LiPF lithium hexafluorophosphate
  • 6 Stir evenly to form a basic electrolyte, wherein the concentration of LiPF 6 is 1.15 mol/L.
  • other additives were added according to the amounts and types provided in the table below to obtain the electrolytes of the respective examples and comparative examples.
  • the positive active material lithium cobalt oxide (LiCoO 2 ), the conductive agent carbon nanotube (CNT), and the binder polyvinylidene fluoride are mixed according to the weight ratio of 95:2:3, and N-methylpyrrolidone (NMP) is added,
  • NMP N-methylpyrrolidone
  • the system was stirred under the action of a vacuum mixer until a uniform positive electrode slurry was formed, and the positive electrode slurry was uniformly coated on the positive electrode current collector aluminum foil. After drying at 85°C, the positive electrode active material layer was obtained by cold pressing, and then the tabs were cut, cut, welded, and then dried at 85°C under vacuum for 4 hours to obtain the positive electrode.
  • the negative electrode active material graphite, styrene-butadiene rubber (SBR), and sodium carboxymethylcellulose (CMC) are fully stirred and mixed in an appropriate amount of deionized water solvent according to the weight ratio of 95:2:3 to form a uniform negative electrode slurry. ; Coat the slurry on the negative electrode current collector copper foil, dry and cold-press to obtain the negative electrode active material layer, and then cut, cut, and weld the tabs, and then dry at 85 °C for 4 hours under vacuum conditions to obtain the negative electrode active material layer. negative electrode.
  • a polyethylene (PE) film was used as the separator.
  • the positive electrode, the separator, and the negative electrode are stacked in order, so that the separator is placed between the positive electrode and the negative electrode to isolate the positive electrode and the negative electrode, and then rolled and placed in the outer packaging foil.
  • the preparation of the lithium ion battery is completed after the processes of vacuum packaging, standing, chemical formation, shaping and the like.
  • the lithium-ion battery was charged to 4.45V with a constant current of 0.7C, charged with a constant voltage of 4.45V to a current of 0.05C, and then discharged with a constant current of 1C to 3.0V. This is the first cycle, and the first cycle discharge is recorded. capacity.
  • the lithium-ion battery was cycled a number of times under the above conditions. Taking the capacity of the first discharge as 100%, the charge-discharge cycle was repeated. When the discharge capacity decreased to 80%, the test was stopped, and the number of cycles at 25°C was recorded as an index for evaluating the cycle performance of lithium-ion batteries.
  • the lithium-ion battery was charged to 4.45V with a constant current of 0.7C and a constant voltage of 4.45V to a current of 0.05C. Place the battery in a high temperature box, heat it to 135°C with a temperature rise rate of 5 ⁇ 2°C/min, and then keep it for 1 hour, if the battery does not catch fire, explode, or emit smoke, the test is passed. Test 10 batteries in each group, and record the number of batteries that pass the test.
  • Thickness expansion rate ( %) (H 1 ⁇ H 0 )/H 0 ⁇ 100%.
  • a small sample is randomly taken from the negative electrode, placed in a scanning electron microscope, and used in conjunction with an energy dispersive spectrometer to characterize the element species and identify whether there is a large amount of copper. As shown in FIG. 2 , it is considered that there is copper precipitation when a luminous area (ie, a copper precipitation area) is observed in the negative electrode in the scanning electron microscope.
  • Table 1 provides data and test results for Examples 1-1 to 1-18 and Comparative Examples 1-1 to 1-8.
  • the content of the compound of formula I and lithium difluorophosphate in Table 1 is in % by weight based on the total weight of the electrolyte.
  • the compound of formula I combined with LiPO 2 F 2 can unexpectedly improve the 25°C cycle cycle stability and improve the hot box test pass of the battery Rate.
  • the reduction potential of the compound of formula I is high, and it can preferentially form a film on the negative electrode.
  • LiPO 2 F 2 has a protective effect on the positive and negative electrodes. When the compound of formula I and LiPO 2 F 2 exist at the same time, it can protect the positive and negative electrodes of the battery more. It is sufficient, which is beneficial to improve the high voltage stability and high temperature stability of the battery, thereby improving the 25 °C cycle performance of the battery and the pass rate of the hot box test of the battery. Better performance can be obtained.
  • the electrode solution of the present application may further comprise a first additive comprising a compound of formula II.
  • a first additive comprising a compound of formula II.
  • Table 2 The data and test results of Examples 2-1 to 2-9 and Comparative Examples 1-1, 2-1 and 2-2 are provided in Table 2.
  • the contents of N-acetyl caprolactam, lithium difluorophosphate and the first additive in Table 2 are in wt % based on the total weight of the electrolyte.
  • the electrolytic solution further contained the first additive, more excellent cycle performance and safety performance were achieved.
  • the compound of formula II contains both a cyano functional group and a double bond, which can protect the positive and negative electrodes at the same time.
  • the compound of formula I and LiPO 2 F 2 When used in combination with the compound of formula I and LiPO 2 F 2 , it can synergistically play a role in protecting the interface of the positive and negative electrodes. The stability of the positive and negative interfaces is further improved, so that the electrical properties and safety properties are further improved.
  • the electrode solution of the present application may also include a second additive, and the second additive comprises the compound of formula III.
  • the data and test results of Examples 3-1 to 3-8 and Comparative Examples 1-1, 3-1 and 3-2 are provided in Table 3.
  • the contents of N-acetyl caprolactam, lithium difluorophosphate and the second additive in Table 3 are in % by weight based on the total weight of the electrolyte.
  • the electrolyte of the present application may contain both the second additive and the third additive.
  • the data and test results for Examples 4-1 to 4-9 and Comparative Example 4-1 are provided in Table 4 below.
  • the contents of N-acetyl caprolactam, lithium difluorophosphate, the second additive and the third additive in Table 4 are in % by weight based on the total weight of the electrolyte.
  • the ratio between the third additive and the second additive has a significant effect on inhibiting the corrosion of copper foil. It can be found from the comparison of Examples 4-1 to 4-13 that the second additive is used alone. It will lead to an increase in the corrosion effect on the copper foil, and with the addition of the third additive, the corrosion of the copper foil is improved to a certain extent. When the amount of the third additive is not less than the amount of the second additive, the copper foil can be avoided. corrosion.
  • the positive electrode in the electrochemical device of the present application may include an insulating layer, and the effect of the positive electrode insulating layer on the battery performance is shown in Table 5 below.
  • the insulating layer in Example 5-1 is located in the empty foil area on the same side as the positive active material layer on the first surface, there is a gap of 1 mm between the insulating layer and the first surface active material layer, and the inorganic particles in the insulating layer are alumina, polymerized
  • the compound is a homopolymer of vinylidene fluoride with a thickness of 10 ⁇ m; in Example 5-2, the inorganic particles are magnesium oxide, and the polymer is a homopolymer of vinylidene fluoride with a thickness of 10 ⁇ m.
  • the presence of the insulating layer can improve the thermal stability of the battery without any deterioration in other electrical properties. At present, its mechanism of action is still unclear. It is speculated that the existence of the insulating layer can reduce the exposure of the metal aluminum substrate and reduce its contact with the electrolyte. Since the positive electrode of the battery is in a high potential state in a fully charged state, the corresponding high-potential metal aluminum is easily contacted with the electrolyte to cause a chemical reaction to promote the increase of heat production. Heat increases the throughput of the hot box.

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Abstract

本申请涉及一种电解液，该电解液包括式I化合物和二氟磷酸锂，其中，X选自经取代或未经取代的C1-10烷基、经取代或未经取代的C2-10烯基、经取代或未经取代的C1-5烷基磺酰基和经取代或未经取代的C2-5酰基，经取代时，取代基选自氰基和卤素。本申请还涉及包含该电解液的电化学装置和电子装置。

Description

电解液和包含电解液的电化学装置及电子装置 技术领域
本申请涉及储能技术领域，尤其涉及一种电解液以及包括该电解液的电化学装置和电子装置。
背景技术
随着智能产品的普及和应用，人们对手机、笔记本、相机等电子产品的需求逐年增加。锂离子电池作为电子产品的工作电源，具有能量密度高、无记忆效应、工作电压高等特点，正逐步取代传统的Ni-Cd和MH-Ni电池。然而随着电子产品向轻薄化和便携化的发展，人们对锂离子电池的要求不断提高，开发安全性高、长寿命的锂离子电池是市场的主要需求之一。
发明内容
本申请通过提供一种电解液以解决至少一种存在于相关领域中的问题。特别地，本申请提供的电解液能够显著改善电化学装置的热箱和常温循环性能。本申请还涉及包含这种电解液的电化学装置和电子装置。
本申请提供一种电解液，其包括式I化合物和二氟磷酸锂，
Figure PCTCN2020108961-appb-000001
其中，X选自经取代或未经取代的C 1-10烷基、经取代或未经取代的C 2-10烯基、经取代或未经取代的C 1-5烷基磺酰基和经取代或未经取代的C 2-5酰基，经取代时，取代基选自氰基和卤素。
在一些实施例中，式I化合物选自N-乙酰基己内酰胺、N-乙烯基己内酰胺、N-甲基己内酰胺、N-三氟甲基己内酰胺或N-甲磺酰基己内酰胺中的至少一种。
在一些实施例中，基于所述电解液的总重量，所述式I化合物的含量为0.01％至3％，所述二氟磷酸锂的含量为0.01％至1％。
在一些实施例中，基于所述电解液的总重量，所述式I化合物的含量为a％，所述二氟磷酸锂的含量为b％，电解液中式I化合物与二氟磷酸锂的含量比a/b为0.01至30。
在一些实施例中，本申请的电解液进一步包含以下化合物中的至少一种：
(1)第一添加剂，所述第一添加剂包含式II化合物，基于所述电解液的总重量，所述第一添加剂的含量为0.01％至5％：
Figure PCTCN2020108961-appb-000002
其中R 1、R 2、R 3各自独立地选自氢、卤素、经取代或未经取代的C 1-12烷基、经取代或未经取代的C 3-8环烷基和经取代或未经取代的C 6-12芳基，经取代时，取代基选自氰基、硝基、卤素和磺酰基，n为0至7的整数；
(2)第二添加剂，所述第二添加剂包含式III化合物，基于所述电解液的总重量，所述第二添加剂的含量为0.1％至5％：
Figure PCTCN2020108961-appb-000003
其中R 4、R 5、R 6各自独立地选自经取代或未经取代的C 1-12亚烷基、经取代或未经取代的C 2-12亚烯基、R 0-S-R基团、R 0-O-R基团或O-R基团，R 7选自H、氟、氰基、经取代或未经取代的C 1-12烷基、经取代或未经取代的C 2-12烯基、R 0-S-R基团、R 0-O-R基团或O-R基团， 其中R 0和R各自独立地选自经取代或未经取代的C 1-6亚烷基；经取代时，取代基选自卤素、氰基、C 1-6烷基、C 2-6烯基和其任意组合；
(3)第三添加剂，所述第三添加剂包含二腈或醚二腈化合物，基于所述电解液的总重量，所述第三添加剂的含量为1％至8％；及
(4)第四添加剂，所述第四添加剂包含1,3-丙烷磺内酯、硫酸乙烯酯或氟代碳酸乙烯酯中的至少一种，基于所述电解液的总重量，所述第四添加剂的含量为0.1％至10％。
在一些实施例中，所述式II化合物包括丙烯腈、丁烯腈、甲基丙烯腈、3-甲基丁烯腈、2-戊烯腈、2-甲基-2丁烯腈或2-甲基-2戊烯腈中的至少一种；所述式III化合物包括以下化合物中的至少一种：
Figure PCTCN2020108961-appb-000004
Figure PCTCN2020108961-appb-000005
所述二腈或醚二腈化合物包括丙二腈、丁二腈、戊二腈、己二腈、庚二腈、辛二腈、壬二腈、癸二腈、四甲基丁二腈、2-甲基戊二腈、2-亚甲基戊二腈、2,4-二甲基戊二腈、2,2,4,4-四甲基戊二腈或乙二醇双(丙腈)醚中的至少一种。
在一些实施例中，电解液进一步包括有机溶剂和锂盐，所述有机溶剂包括选自碳酸乙烯酯、碳酸丙烯酯、碳酸二甲酯、碳酸二乙酯、碳酸甲乙酯、乙酸乙酯、丙酸甲酯、丙酸乙酯或丙酸丙酯中的至少一种；所述锂盐包括选自六氟磷酸锂、双三氟甲烷磺酰亚胺锂、双(氟磺酰)亚胺锂、四氟硼酸锂、双草酸硼酸锂或二氟草酸硼酸锂中的至少一种。
本申请还提供一种电化学装置，其包括根据本申请的电解液。
在一些实施例中，本申请的电化学装置还包括正极，所述正极包括：
正极集流体；
正极活性材料层；和
绝缘层，所述绝缘层设置于所述正极集流体上，所述绝缘层满足条件(a)至(c)中的至少一者：
(a)所述绝缘层与所述正极活性材料层间有空隙，所述空隙的宽度小于等于2mm；
(b)所述绝缘层包括无机粒子，所述无机粒子包括氧化铝、二氧化硅、氧化镁、氧化钛、二氧化铪、氧化锡、二氧化铈、氧化镍、氧化锌、氧化钙、二氧化锆、氧化钇、碳化硅、勃姆石、氢氧化铝、氢氧化镁、氢氧化钙或硫酸钡中的至少一种；
(c)所述绝缘层包括聚合物，所述聚合物包括偏氟乙烯的均聚物、偏氟乙烯的共聚物、六氟丙烯的共聚物、聚苯乙烯、聚苯乙炔、聚乙烯酸钠、聚乙烯酸钾、聚甲基丙烯酸甲酯、聚乙烯、聚丙烯或聚四氟乙烯中的至少一种。
本申请还提供一种电子装置，其包括根据本申请的电化学装置。
本申请实施例的额外层面及优点将部分地在后续说明中描述、显示、或是经由本申请实施例的实施而阐释。
附图说明
在下文中将简要地说明为了描述本申请实施例或现有技术所必要的附图以便于描述本申请的实施例。显而易见地，下文描述中的附图仅只是本申请中的部分实施例。对本领域技术人员而言，依然可以根据这些附图中所例示的结构来获得其他实施例的附图。
图1-A和图1-B示出根据本申请的正极，其中正极包含正极集流体(1)、第一表面正极活性物质层(2)、第二表面活性物质层(3)和绝缘层(4)。
图2示出负极析铜测试的扫描电镜图。
具体实施方式
本申请的实施例将会被详细的描示在下文中。在本申请说明书全文中，将相同或相似的组件以及具有相同或相似的功能的组件通过类似附图标记来表示。在此所描述的有关附图的实施例为说明性质的、图解性质的且用于提供对本申请的基本理解。本申请的实施例不应该被解释为对本申请的限制。
如本文中所使用，术语“约”用以描述及说明小的变化。当与事件或情形结合使用时，所述术语可指代其中事件或情形精确发生的例子以及其中事件或情形极近似地发生的例子。举例来说，当结合数值使用时，术语可指代小于或等于所述数值的±10％的变化范围，例如小于或等于±5％、小于或等于±4％、小于或等于±3％、小于或等于±2％、小于或等于±1％、小于或等于±0.5％、小于或等于±0.1％、或小于或等于±0.05％。举例来说，如果两个数值之间的差值小于或等于所述值的平均值的±10％(例如小于或等于±5％、小于或等于±4％、小于或等于±3％、小于或等于±2％、小于或等于±1％、小于或等于±0.5％、小于或等于±0.1％、或小于或等于±0.05％)，那么可认为所述两个数值“约”相同。
在本说明书中，除非经特别指定或限定之外，相对性的用词例如：“中央的”、“纵向的”、“侧向的”、“前方的”、“后方的”、“右方的”、“左方的”、“内部的”、“外部的”、“较低的”、“较高的”、“水平的”、“垂直的”、“高于”、“低于”、“上方的”、“下方的”、“顶部的”、“底部的”以及其衍生性的用词(例如“水平地”、“向下地”、“向上地”等等)应该解释成引用在讨论中所描述或在附图中所描示的方向。这些相对性的用词仅用于描述上的方便，且并不要求将本申请以特定的方向建构或操作。
再者，为便于描述，“第一”、“第二”、“第三”等等可在本文中用于区分一个图或一系列图的不同组件。“第一”、“第二”、“第三”等等不意欲描述对应组件。
另外，有时在本文中以范围格式呈现量、比率和其它数值。应理解，此类范围格式是用于便利及简洁起见，且应灵活地理解，不仅包含明确地指定为范围限制的数值，而且包含涵盖于所述范围内的所有个别数值或子范围，如同明确地指定每一数值及子范围一般。
在具体实施方式及权利要求书中，由术语“中的一者”、“中的一个”、“中的一种”或其他相似术语所连接的项目的列表可意味着所列项目中的任一者。例如，如果列出项目A及B，那么短语“A及B中的一者”意味着仅A或仅B。在另一实例中，如果列出项目A、B及C，那么短语“A、B及C中的一者”意味着仅A；仅B；或仅C。项目A可包含单个元件或多个元件。项目B可包含单个元件或多个元件。项目C可包含单个元件或多个元件。
在具体实施方式及权利要求书中，由术语“中的至少一者”、“中的至少一个”、“中的至少一种”或其他相似术语所连接的项目的列表可意味着所列项目的任何组合。例如，如果列出项目A及B，那么短语“A及B中的至少一者”意味着仅A；仅B；或A及B。在另一实例中，如果列出项目A、B及C，那么短语“A、B及C中的至少一者”意味着仅A；或仅B；仅C；A及B(排除C)；A及C(排除B)；B及C(排除A)；或A、B及C的全部。项目A可包含单个元件或多个元件。项目B可包含单个元件或多个元件。项目C可包含单个元件或多个元件。
本申请中使用下列定义(除非另外明确地说明)：
为简单起见，“C n-m”基团是指具有“n”至“m”个碳原子的基团，其中“n”和“m”是整数。例如，“C 1-10”烷基是具有1至10个碳原子的烷基。
术语“烷基”预期是具有1至20个碳原子的直链饱和烃结构。“烷基”还预期是具有3至20个碳原子的支链或环状烃结构。例如，烷基可为1至20个碳原子的烷基、1至10个碳原子的烷基、1至5个碳原子的烷基、5至20个碳原子的烷基、5至15个碳原子的烷基或5至10个碳原子的烷基。当指定具有具体碳数的烷基时，预期涵盖具有该碳数的所有几何异构体；因此，例如，“丁基”意思是包括正丁基、仲丁基、异丁基、叔丁基和环丁基；“丙基”包括正丙基、异丙基和环丙基。烷基实例包括，但不限于甲基、乙基、正丙基、异丙基、环丙基、正丁基、异丁基、仲丁基、叔丁基、环丁基、 正戊基、异戊基、新戊基、环戊基、甲基环戊基、乙基环戊基、正己基、异己基、环己基、正庚基、辛基、环丙基、环丁基、降冰片基等。另外，烷基可以是任选地被取代的。
术语“烯基”是指可为直链或具支链且具有至少一个且通常1个、2个或3个碳碳双键的单价不饱和烃基团。除非另有定义，否则所述烯基通常含有2至20个碳原子，例如可以为2至20个碳原子的烯基、6至20个碳原子的烯基、2至10个碳原子的烯基或2至6个碳原子的烯基。代表性烯基包括(例如)乙烯基、正丙烯基、异丙烯基、正-丁-2-烯基、丁-3-烯基、正-己-3-烯基等。另外，烯基可以是任选地被取代的。
术语“亚烷基”意指可为直链或具支链的二价饱和烷基。除非另有定义，否则所述亚烷基通常含有1到10个、1至6个、1至4个或2至4个碳原子，且包括(例如)C 2-3亚烷基和C 2-6亚烷基。代表性亚烷基包括(例如)亚甲基、乙烷-1,2-二基(“亚乙基”)、丙烷-1,2-二基、丙烷-1,3-二基、丁烷-1,4-二基、戊烷-1,5-二基等。
术语“亚烯基”意指通过从上述定义的烯基中除去一个氢原子而获得的双官能团。优选的亚烯基包括但不限于-CH＝CH-、-C(CH 3)＝CH-、-CH＝CHCH 2–等。
术语“环烷基”涵盖环状烷基。环烷基可为2～20个碳原子的环烷基、6～20个碳原子的环烷基、2～10个碳原子的环烷基、2～6个碳原子的环烷基。例如，环烷基可为环丙基、环丁基、环戊基、环己基等。另外，环烷基可以是任选地被取代的。
术语“芳基”意指具有单环(例如，苯基)或稠合环的单价芳香族烃。稠合环***包括那些完全不饱和的环***(例如，萘)以及那些部分不饱和的环***(例如，1,2,3,4-四氢萘)。除非另有定义，否则所述芳基通常含有6个到26个、6至20个、6至15个或6至10个碳环原子且包括(例如)C 6-10芳基。代表性芳基包括(例如)苯基、甲基苯基、丙基苯基、异丙基苯基、苯甲基和萘-1-基、萘-2-基等等。
术语“烷基磺酰基”意指基团-S(＝O) 2-R，其中R是上文定义的烷基。
术语“酰基”意指基团-C(＝O)-R，其中R是上文定义的烷基。
术语“杂环”或“杂环基”意指取代或未取代的5至8元单或双环非芳族烃，其中1至3个碳原子被选自氮、氧或硫原子的杂原子替换。实例包括吡咯烷-2-基；吡咯烷-3-基；哌啶基；吗啉-4-基等，这些基团随后可被取代。“杂原子”是指选自N、O和S的原子。
如本文所用，术语“卤素”可为F、Cl、Br或I。
如本文所用，术语“氰基”涵盖含有机基团-CN的有机物。
当上述取代基经取代时，取代基可选自由以下组成的群组：卤素、烷基、烯基、芳基和杂芳基。
一、电解液
1、式I化合物和二氟磷酸锂
本申请提供一种电解液，其包括式I化合物和二氟磷酸锂，
Figure PCTCN2020108961-appb-000006
其中，X选自经取代或未经取代的C 1-10烷基、经取代或未经取代的C 2-10烯基、经取代或未经取代的C 1-5烷基磺酰基和经取代或未经取代的C 2-5酰基，经取代时，取代基包括但不限于氰基和卤素等。
在一些实施例中，式I化合物选自N-乙酰基己内酰胺、N-乙烯基己内酰胺、N-甲基己内酰胺、N-三氟甲基己内酰胺或N-甲磺酰基己内酰胺中的至少一种。
在一些实施例中，基于电解液的总重量，式I化合物的含量为0.01％至3％。例如，式I化合物的含量可以为0.01％、0.1％、0.5％、1％、1.5％、2％、2.5％、3％，或者为上述任意两个数值之间的范围。
在一些实施例中，基于电解液的总重量，二氟磷酸锂的含量为0.01％至1％。例如，二氟磷酸锂的含量可以为0.01％、0.1％、0.2％、0.3％、0.4％、0.49％、0.5％、0.6％、0.7％、0.8％、0.9％、1％，或者为上述任意两个数值之间的范围。
在一些实施例中，基于电解液的总重量，式I化合物的含量为0.5％至2％，且二氟磷酸锂的含量范围可以为0.1％至0.5％；当式I化合物和二氟磷酸锂的含量上述范围内时，其组合可以显著地改善电化学装置的循环稳定性和热箱性能。
在一些实施例中，基于电解液的总重量，式I化合物的含量为a％，二氟磷酸锂的含量为b％，电解液中式I化合物与二氟磷酸锂的含量比a/b为0.01至30。例如，式I化合物与二氟磷酸锂的含量比a/b可以为0.01、0.1、1、1.5、1.6、1.7、2、2.5、3、3.3、3.5、4、5、 6、6.5、6.6、6.7、7、8、10、15、18、20、25、30，或者为上述任意两个数值之间的范围。在一些实施例中，电解液中式I化合物与二氟磷酸锂的含量比a/b为1.5至10，当质量比在该范围内时，可以更好地兼顾常温循环性能和热箱性能的改善。
本申请的发明人出人意料地发现，除了用于改善高温存储性能外，上述式I化合物还可以用于改善电化学装置的安全性能。当将式I化合物与二氟磷酸锂组合使用时，对电池的正负极的保护更加充分，有利于提高电池的高电压稳定性及高温稳定性，降低阻抗，进而提升电化学装置的常温循环性能及电池的热箱性能。
2、第一添加剂
在一些实施例中，本申请的电解液进一步包含第一添加剂，第一添加剂包含式II化合物：
Figure PCTCN2020108961-appb-000007
其中R 1、R 2、R 3各自独立地选自氢、卤素、经取代或未经取代的C 1-12烷基、经取代或未经取代的C 3-8环烷基和经取代或未经取代的C 6-12芳基，经取代时，取代基选自氰基、硝基、卤素和磺酰基，n为0至7的整数。在式II中，烷基、环烷基和芳基具有如上文限定的定义；n可以为1、2、3、4、5、或6。
在一些实施例中，式II化合物包括丙烯腈、丁烯腈、甲基丙烯腈、3-甲基丁烯腈、2-戊烯腈、2-甲基-2丁烯腈或2-甲基-2戊烯腈中的至少一种。
在一些实施例中，基于电解液的总重量，第一添加剂的含量为0.01％至5％，例如，可以为0.01％、0.1％、0.2％、0.3％、0.4％、0.5％、1％、2％、3％、4％、5％，或者为上述任意两个数值之间的范围。当第一添加剂在上述范围内时，可以更有效地在负极形成保护膜，从而发挥对负极的保护作用，改善电化学装置的高温稳定性。
3、第二添加剂
在一些实施例中，本申请的电解液进一步包含第二添加剂，第二添加剂包含式III化合物：
Figure PCTCN2020108961-appb-000008
其中R 4、R 5、R 6各自独立地选自经取代或未经取代的C 1-12亚烷基、经取代或未经取代的C 2-12亚烯基、R 0-S-R基团、R 0-O-R基团或O-R基团，R 7选自H、氟、氰基、经取代或未经取代的C 1-12烷基、经取代或未经取代的C 2-12烯基、R 0-S-R基团、R 0-O-R基团或O-R基团，其中R 0和R各自独立地选自经取代或未经取代的C 1-6亚烷基；经取代时，取代基选自卤素、氰基、C 1-6烷基、C 2-6烯基和其任意组合。
在一些实施例中，式III化合物包括以下化合物中的至少一种：
Figure PCTCN2020108961-appb-000009
Figure PCTCN2020108961-appb-000010
在一些实施例中，基于电解液的总重量，第二添加剂的含量为0.1％至5％，例如，可以为0.1％、0.5％、1％、2％、3％、4％、5％，或者为上述任意两个数值之间的范围。当式III化合物的含量在上述范围内，可以更好地改善电化学装置的安全性能。
4、第三添加剂
在一些实施例中，本申请的电解液进一步包含第三添加剂，第三添加剂包含二腈或醚二腈化合物。
在一些实施例中，第三添加剂包括丙二腈、丁二腈、戊二腈、己二腈、庚二腈、辛二腈、壬二腈、癸二腈、四甲基丁二腈、2-甲基戊二腈、2-亚甲基戊二腈、2,4-二甲基戊二腈、2,2,4,4-四甲基戊二腈或乙二醇双(丙腈)醚中的至少一种。
在一些实施例中，基于电解液的总重量，第三添加剂的含量为1％至8％，例如，可以为1％、2％、3％、4％、5％、6％、7％、8％，或者为上述任意两个数值之间的范围。
在一些实施例中，电解液中第三添加剂的含量不少于第二添加剂的含量。在一些实施例中，第三添加剂(二腈或醚二腈化合物)的含量大于第二添加剂(式III化合物)的含量。当第三添加剂的含量不少于第二添加剂的含量时，第三添加剂能够有效地抑制由式III化合物引起的对铜箔的腐蚀作用。
5、第四添加剂
在一些实施例中，本申请的电解液进一步包含第四添加剂，第四添加剂选自1,3-丙烷磺内酯(PS)、硫酸乙烯酯(DTD)或氟代碳酸乙烯酯(FEC)中的至少一种。
在一些实施例中，基于所述电解液的总重量，第四添加剂的含量为0.1％至10％，例如，可以为0.1％、0.5％、1％、2％、3％、4％、5％、6％、7％、8％、9％、10％，或者为上述任意两个数值之间的范围。
6、有机溶剂和锂盐
在一些实施例中，电解液进一步包括有机溶剂和锂盐。
在一些实施例中，有机溶剂包括选自碳酸乙烯酯(EC)、碳酸丙烯酯(PC)、碳酸二甲酯(DMC)、碳酸二乙酯(DEC)、碳酸甲乙酯(EMC)、γ-丁内酯(BL)、丙酸甲酯(MP)、乙酸乙酯(EA)、丙酸乙酯(EP)或丙酸丙酯(PP)的中的至少一种。在一些实施例中，锂盐包括选自六氟磷酸锂(LiPF 6)、双三氟甲烷磺酰亚胺锂(LiTFSI)、双(氟磺酰)亚胺锂(LiFSI)、四氟硼酸锂(LiBF 4)、双草酸硼酸锂(LiBOB)或二氟草酸硼酸锂(LiDFOB)中的至少一种。
二、电化学装置
本申请还提供一种电化学装置，其包括根据本申请的电解液。在一些实施例中，本申请的电化学装置包括但不限于锂离子电池。
在一些实施例中，电化学装置包含正极，该正极包括：
正极集流体；
正极活性材料层；和
绝缘层，其设置于所述正极集流体上并且满足条件(a)至(c)中的至少一者：
(a)所述绝缘层与所述正极活性材料层间有空隙，所述空隙的宽度小于等于2mm，例如，可以为0、0.5mm、1mm、1.5mm或2mm，或者为上述任意两个数值之间的范围；
(b)所述绝缘层包括无机粒子，所述无机粒子包括氧化铝、二氧化硅、氧化镁、氧化钛、二氧化铪、氧化锡、二氧化铈、氧化镍、氧化锌、氧化钙、二氧化锆、氧化钇、碳化硅、勃姆石、氢氧化铝、氢氧化镁、氢氧化钙或硫酸钡中的至少一种；
(c)所述绝缘层包括聚合物，所述聚合物包括偏氟乙烯的均聚物、偏氟乙烯的共聚物、六氟丙烯的共聚物、聚苯乙烯、聚苯乙炔、聚乙烯酸钠、聚乙烯酸钾、聚甲基丙烯酸甲酯、聚乙烯、聚丙烯或聚四氟乙烯中的至少一种。
在一些实施例中，绝缘层满足上述条件(a)。具体而言，如附图1-A和附图1-B中所示出的，正极包含正极集流体(1)、第一表面正极活性物质层(2)、第二表面活性物质层(3)和绝缘层(4)，其中，正极集流体上除了活性物质层覆盖的区域外，还包括没有活性物质层覆盖的区域(也称作空箔区域)。第一表面正极活性物质层(2)较第二表面活性物质层(3)短，绝缘层(4)位于集流体上第一表面正极活性物质层同一侧的空箔区域，绝缘层两端与第一表面活性物质层之间有约0至约2mm的空隙。正极一般包括正极集流体、正极活性物质层等。在热滥用测试中，铝集流体处于较高的电位，与电解液接触容易产生较多的热量，因此，通过在空箔区上设置一层绝缘层可以有效的保护正极中的正极集流体的空箔区域，减少其与电解液的直接接触，有利于减少产热量。满足条件(a)的正极与本申请所述的电解液结合，有利于提升电池的整体热稳定性，进一步提升热箱的通过温度。
在一些实施例中，绝缘层的厚度为1μm-20μm，例如，可以为1μm、2.5μm、5μm、7.5μm、10μm、12μm、14μm、16μm、18μm或20μm，或者为上述任意两个数值之间的范围。
在本申请中，正极活性材料的具体种类不做特殊限制，可根据需求进行选择，具体地，可选自钴酸锂(LiCoO 2)、锂镍钴锰(NCM)、锂镍钴铝(NCA)等三元材料、磷酸亚铁锂(LiFePO 4)或锰酸锂(LiMn 2O 4)中的至少一种。
在一些实施例中，电化学装置还包含负极，负极包含负极集流体和负极活性材料层。在本申请中，负极活性材料的具体种类均不受到具体的限制，可根据需求进行选择。具体地，所述负极活性材料选自锂金属、结构化的锂金属、天然石墨、人造石墨、中间相微碳球(简称为MCMB)、硬碳、软碳、硅、硅-碳复合物、Li-Sn合金、Li-Sn-O合金、Sn、SnO、SnO 2、尖晶石结构的锂化TiO 2-Li 4Ti 5O 12或Li-Al合金中的至少一种。
在一些实施例中，电化学装置还包含隔离膜，隔离膜材料的具体种类均不受到具体的限制，可根据需求进行选择。具体地，隔离膜可选自聚乙烯膜、聚丙烯膜、聚偏氟乙烯膜以及他们的多层复合膜，也可根据实际需要在隔离膜基材表面涂覆无机或有机物质以增强电池的硬度或提升隔离膜与正负极界面的粘结性。
三、电子装置
本申请还提供一种电子装置，其包括根据本申请的电化学装置。
本申请的电子装置的类型没有特别限定。在一些实施例中，本申请的电子学装置可 以包括用于，但不限于，笔记本电脑、笔输入型计算机、移动电脑、电子书播放器、便携式电话、便携式传真机、便携式复印机、便携式打印机、头戴式立体声耳机、录像机、液晶电视、手提式清洁器、便携CD机、迷你光盘、收发机、电子记事本、计算器、存储卡、便携式录音机、收音机、备用电源、电机、汽车、摩托车、助力自行车、自行车、照明器具、玩具、游戏机、钟表、电动工具、闪光灯、照相机、家庭用大型蓄电池和锂离子电容器等。
实施例
下面结合实施例，进一步阐述本申请。应理解，这些实施例仅用于说明本申请而不用于限制本申请的范围。
1、制备方法
实施例以及对比例中的锂离子电池均按照下述方法进行制备：
(1)电解液制备
在含水量小于10ppm的氩气气氛手套箱中，将碳酸乙烯酯(EC)、碳酸丙烯酯(PC)、碳酸二乙酯(DEC)按重量比1:1:1均匀混合，加入六氟磷酸锂(LiPF 6)搅拌均匀，形成基础电解液，其中LiPF 6的浓度为1.15mol/L。在该基础电解液中，根据下文表格中提供的用量和种类分别添加其他添加剂以得到各个实施例和对比例的电解液。
(2)正极制备
将正极活性材料钴酸锂(LiCoO 2)、导电剂碳纳米管(CNT)、粘结剂聚偏二氟乙烯按照重量比95:2:3进行混合，加入N-甲基吡咯烷酮(NMP)，在真空搅拌机作用下搅拌直至体系形成均一的正极浆料，将此正极浆料均匀涂覆于正极集流体铝箔上。在85℃下烘干后经过冷压得到正极活性物质层，再经过裁片、分切、焊接极耳，然后在85℃的真空条件下干燥4h，得到正极。
(3)负极制备
将负极活性物质石墨、丁苯橡胶(SBR)、羧甲基纤维素钠(CMC)按照重量比95:2:3在适量的去离子水溶剂中充分搅拌混合，使其形成均匀的负极浆料；将此浆料涂覆于负极集流体铜箔上，烘干、冷压得到负极活性物质层，再经过裁片、分切、焊接极耳，然后在85℃的真空条件下干燥4h，得到负极。
(4)隔离膜制备
使用聚乙烯(PE)膜作为隔离膜。
(5)锂离子电池的制备
将正极、隔离膜、负极按顺序叠好，使隔离膜处于正极和负极之间起到隔离的作用，然后卷绕，置于外包装箔中，将根据各个实施例和对比例制备的电解液注入到干燥后的电池中，经过真空封装、静置、化成、整形等工序，即完成锂离子电池的制备。
2、测试方法
(1)锂离子电池的室温循环容量保持率的测试方法
在25℃下，将锂离子电池以0.7C恒流充电至4.45V，4.45V恒压充电至电流为0.05C，再用1C恒流放电至3.0V，此时为首次循环，记录首次循环放电容量。按照上述条件使锂离子电池进行多次循环。以首次放电的容量为100％，反复进行充放电循环，至放电容量衰减至80％时，停止测试，记录在25℃循环圈数，作为评价锂离子电池循环性能的指标。
(2)热箱测试
在25℃下，将锂离子电池以0.7C恒流充电至4.45V，4.45V恒压充电至电流为0.05C。将电池放置在高温箱中，用5±2℃/分钟的温升速率加热到135℃，然后保持1h，电池不起火、不***、不冒烟即为通过测试。每组测试10个电池，记录通过测试电池个数。
(3)高温存储测试
在25℃下，将锂离子电池静置30分钟；然后以0.5C倍率恒流充电至4.45V，再在4.45V下恒压充电至0.05C，静置5分钟，测试锂离子电池的厚度并记为H 0；然后将锂离子电池放入85℃的恒温箱储存24天，测试锂离子电池的厚度并记为H 1，并通过下式计算锂离子电池的厚度膨胀率：厚度膨胀率(％)＝(H 1-H 0)/H 0×100％。
(4)负极析铜测试
在负极随机取一小块样品，置于扫描电镜中，与能谱仪联用，进行元素种类的表征，鉴定是否有大量铜元素。如图2中所示，扫描电镜中观察到负极存在发亮区域(即析铜区域)，则认为有铜析出。
3、测试结果
(1)式I化合物和LiPO 2F 2对电池性能的影响
表1中提供实施例1-1至1-18和对比例1-1至1-8的数据以及测试结果。表1中式I化合物和二氟磷酸锂的含量以基于电解液总重量的重量％计。
表1
Figure PCTCN2020108961-appb-000011
如表1所示，从以上对比例及实施例的测试结构可以看出，式I化合物与LiPO 2F 2联用可出人意料地改善25℃循环圈数循环稳定性并且提高电池的热箱测试通过率。式I化合物的还原电位较高，可在负极优先成膜，LiPO 2F 2对正负极均有保护作用，式I化合物与LiPO 2F 2同时存在时，可对电池的正负极保护更加充分，有利于提高电池的高电压稳定性及高温稳定性，进而提升电池的25℃循环性能及电池的热箱测试通过率，在式I化合物与LiPO 2F 2含比为0.01至30，电池能够得到更优异的性能。
(2)第一添加剂对电池性能的影响
本申请的电极液还可以包含第一添加剂，第一添加剂包含式II化合物。表2中提供实施例2-1至2-9和对比例1-1、2-1和2-2的数据以及测试结果。表2中N-乙酰基己内酰胺、二氟磷酸锂和第一添加剂的含量以基于电解液总重量的重量％计。
表2
Figure PCTCN2020108961-appb-000012
如表2中所示，当电解液进一步包含第一添加剂时，实现了更优异的循环性能和安全性能。这是因为：式II化合物同时含有氰基官能团和双键，可对正负极同时予以保护，与式I化合物和LiPO 2F 2组合使用可以协同地发挥对正负极的界面保护作用，从而进一步提升正负极界面的稳定性，使得电性能和安全性能得到进一步改善。
(3)第二添加剂对电池性能的影响
本申请的电极液还可以第二添加剂，第二添加剂包含式III化合物。表3中提供实施 例3-1至3-8和对比例1-1、3-1和3-2的数据以及测试结果。表3中N-乙酰基己内酰胺、二氟磷酸锂和第二添加剂的含量以基于电解液总重量的重量％计。
表3
Figure PCTCN2020108961-appb-000013
如表3所示，当电解液进一步包含第二添加剂时，其热箱通过能力可得到进一步提升，这主要归因于式I化合物、LiPO 2F 2和第二添加剂共同作用，对正极的保护进一步提高，在电池的热滥用测试过程中，正极的稳定性对电池整体的热稳定性起着至关重要的作用。
(4)腈类添加剂对铜箔腐蚀的影响
本申请的电解液可以同时包含第二添加剂和第三添加剂。以下表4中提供实施例4-1至4-9和对比例4-1的数据和测试结果。表4中N-乙酰基己内酰胺、二氟磷酸锂、第二添加剂和第三添加剂的含量以基于电解液总重量的重量％计。
表4
Figure PCTCN2020108961-appb-000014
由上表所示结果可以看出，第三添加剂与第二添加剂之间的比例对于抑制铜箔腐蚀具有显著影响，通过实施例4-1至4-13的对比可以发现，单独使用第二添加剂会导致对于铜箔的腐蚀作用增强，而随着第三添加剂的添加使得铜箔腐蚀得到一定程度的改善，当第三添加剂的用量不少于第二添加剂的用量时，可以避免对铜箔的腐蚀。
(5)正极绝缘层对电池性能的影响
本申请的电化学装置中的正极可以包含绝缘层，以下表5中示出正极绝缘层对电池性能的影响。
表5
Figure PCTCN2020108961-appb-000015
实施例5-1中的绝缘层位于第一表面正极活性物质层同侧的空箔区，绝缘层与第一表面活性物质层之间有1mm的空隙，绝缘层中无机颗粒为氧化铝，聚合物为偏氟乙烯的均聚物，厚度为10μm；实施例5-2中无机颗粒为氧化镁，聚合物为偏氟乙烯的均聚物物，厚度为10μm。
通过表5的数据比对，意外发现，绝缘层的存在可提升电池的热稳定性，同时对其他电性能无任何恶化。目前对于其作用机理尚不明确，推测绝缘层的存在，可减少金属铝基材的暴露，减少其与电解液的接触。由于满充状态电池正极处于高电位状态，相应的处于高电位的金属铝与电解液接触极易发生化学反应促进产热量的增大，通过减少基材的外露，在一定程度上或可减少产热提高热箱的通过率。
整个说明书中对“一些实施例”、“部分实施例”、“一个实施例”、“另一举例”、“举例”、“具体举例”或“部分举例”的引用，其所代表的意思是在本申请中的至少一个实施例或举例包含了该实施例或举例中所描述的特定特征、结构、材料或特性。因此，在整个说明书中的各处所出现的描述，例如：“在一些实施例中”、“在实施例中”、“在一个实施例中”、“在另一个举例中”，“在一个举例中”、“在特定举例中”或“举例“，其不必然是引用本申请中的相同的实施例或示例。此外，本文中的特定特征、结构、材料或特性可以以任何合适的方式在一个或多个实施例或举例中结合。
尽管已经演示和描述了说明性实施例，本领域技术人员应该理解上述实施例不能被解释为对本申请的限制，并且可以在不脱离本申请的精神、原理及范围的情况下对实施例进行改变，替代和修改。

Claims (9)

  1. 一种电解液，所述电解液包括式I化合物和二氟磷酸锂，
    Figure PCTCN2020108961-appb-100001
    其中，X选自经取代或未经取代的C 1-10烷基、经取代或未经取代的C 2-10烯基、经取代或未经取代的C 1-5烷基磺酰基和经取代或未经取代的C 2-5酰基，经取代时，取代基选自氰基和卤素。
  2. 根据权利要求1所述的电解液，其中所述式I化合物选自N-乙酰基己内酰胺、N-乙烯基己内酰胺、N-甲基己内酰胺、N-三氟甲基己内酰胺或N-甲磺酰基己内酰胺中的至少一种。3、根据权利要求1所述的电解液，其中，基于所述电解液的总重量，所述式I化合物的含量为0.01％至3％，所述二氟磷酸锂的含量为0.01％至1％。
  3. 根据权利要求1所述的电解液，其中，基于所述电解液的总重量，所述式I化合物的含量为a％，所述二氟磷酸锂的含量为b％，所述式I化合物与所述二氟磷酸锂的含量比a/b为0.01至30。
  4. 根据权利要求1所述的电解液，其进一步包含以下化合物中的至少一种：
    (1)第一添加剂，所述第一添加剂包含式II化合物，基于所述电解液的总重量，所述第一添加剂的含量为0.01％至5％：
    Figure PCTCN2020108961-appb-100002
    其中R 1、R 2、R 3各自独立地选自氢、卤素、经取代或未经取代的C 1-12烷基、经取代或未经取代的C 3-8环烷基和经取代或未经取代的C 6-12芳基，经取代时，取代基选自氰基、硝基、卤素和磺酰基，n为0至7的整数；
    (2)第二添加剂，所述第二添加剂包含式III化合物，基于所述电解液的总重量，所述第二添加剂的含量为0.1％至5％：
    Figure PCTCN2020108961-appb-100003
    其中R 4、R 5、R 6各自独立地选自经取代或未经取代的C 1-12亚烷基、经取代或未经取代的C 2-12亚烯基、R 0-S-R基团、R 0-O-R基团或O-R基团，R 7选自H、氟、氰基、经取代或未经取代的C 1-12烷基、经取代或未经取代的C 2-12烯基、R 0-S-R基团、R 0-O-R基团或O-R基团，其中R 0和R各自独立地选自经取代或未经取代的C 1-6亚烷基；经取代时，取代基选自卤素、氰基、C 1-6烷基、C 2-6烯基和其任意组合；
    (3)第三添加剂，所述第三添加剂包含二腈或醚二腈化合物，基于所述电解液的总重量，所述第三添加剂的含量为1％至8％；及
    (4)第四添加剂，所述第四添加剂包含1,3-丙烷磺内酯、硫酸乙烯酯或氟代碳酸乙烯酯中的至少一种，基于所述电解液的总重量，所述第四添加剂的含量为0.1％至10％。
  5. 根据权利要求5所述的电解液，其中：
    所述式II化合物包括丙烯腈、丁烯腈、甲基丙烯腈、3-甲基丁烯腈、2-戊烯腈、2-甲基-2丁烯腈或2-甲基-2戊烯腈中的至少一种；
    所述式III化合物包括以下化合物中的至少一种：
    Figure PCTCN2020108961-appb-100004
    Figure PCTCN2020108961-appb-100005
    所述二腈或醚二腈化合物包括丙二腈、丁二腈、戊二腈、己二腈、庚二腈、辛二腈、壬二腈、癸二腈、四甲基丁二腈、2-甲基戊二腈、2-亚甲基戊二腈、2,4-二甲基戊二腈、2,2,4,4-四甲基戊二腈或乙二醇双(丙腈)醚中的至少一种。
  6. 根据权利要求1所述电解液，其中，所述电解液进一步包括有机溶剂和锂盐，所述有机溶剂包括选自碳酸乙烯酯、碳酸丙烯酯、碳酸二甲酯、碳酸二乙酯、碳酸甲乙酯、乙酸乙酯、丙酸甲酯、丙酸乙酯或丙酸丙酯中的至少一种；所述锂盐包括选自六氟磷酸锂、双三氟甲烷磺酰亚胺锂、双(氟磺酰)亚胺锂、四氟硼酸锂、双草酸硼酸锂或二氟草酸硼酸锂中的至少一种。
  7. 一种电化学装置，其包括权利要求1-7中任一项所述的电解液。
  8. 根据权利要求8所述的电化学装置，其还包括正极，所述正极包括：
    正极集流体；
    正极活性材料层；和
    绝缘层，所述绝缘层设置于所述正极集流体上，所述绝缘层满足条件(a)至(c)中的至少一者：
    (a)所述绝缘层与所述正极活性材料层间有空隙，所述空隙的宽度小于等于2mm；
    (b)所述绝缘层包括无机粒子，所述无机粒子包括氧化铝、二氧化硅、氧化镁、氧化钛、二氧化铪、氧化锡、二氧化铈、氧化镍、氧化锌、氧化钙、二氧化锆、氧化钇、碳化硅、勃姆石、氢氧化铝、氢氧化镁、氢氧化钙或硫酸钡中的至少一种；
    (c)所述绝缘层包括聚合物，所述聚合物包括偏氟乙烯的均聚物、偏氟乙烯的共聚物、六氟丙烯的共聚物、聚苯乙烯、聚苯乙炔、聚乙烯酸钠、聚乙烯酸钾、聚甲基丙烯酸甲酯、聚乙烯、聚丙烯或聚四氟乙烯中的至少一种。
  9. 一种电子装置，其包括权利要求8或9所述的电化学装置。
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