WO2022116170A1 - 一种电解液及包含该电解液的电化学装置和电子装置 - Google Patents

一种电解液及包含该电解液的电化学装置和电子装置 Download PDF

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WO2022116170A1
WO2022116170A1 PCT/CN2020/133988 CN2020133988W WO2022116170A1 WO 2022116170 A1 WO2022116170 A1 WO 2022116170A1 CN 2020133988 W CN2020133988 W CN 2020133988W WO 2022116170 A1 WO2022116170 A1 WO 2022116170A1
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substituted
unsubstituted
group
electrolyte
compound
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PCT/CN2020/133988
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English (en)
French (fr)
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熊亚丽
唐超
栗文强
王荣
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宁德新能源科技有限公司
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Priority to PCT/CN2020/133988 priority Critical patent/WO2022116170A1/zh
Priority to CN202080034030.8A priority patent/CN113812027B/zh
Publication of WO2022116170A1 publication Critical patent/WO2022116170A1/zh

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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
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
    • H01M10/0564—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of organic materials only
    • H01M10/0566—Liquid materials
    • H01M10/0567—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
    • H01M10/42—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
    • H01M10/4235—Safety or regulating additives or arrangements in electrodes, separators or 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
    • H01M2300/0017—Non-aqueous electrolytes
    • H01M2300/0025—Organic electrolyte
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

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 containing the electrolyte.
  • Lithium-ion batteries have now become the main unit of 3C portable electronic devices due to their high energy density, long cycle life, low self-discharge rate, no memory effect, stable discharge voltage, fast charge and discharge, and environmental protection.
  • the requirements for lithium-ion batteries are getting higher and higher, such as high energy density and fast charging, which have become the main research directions of many scientific research institutions and battery companies.
  • the power and energy that the lithium battery can provide is proportional to the working voltage
  • increasing the voltage of the battery is the simplest and most direct method.
  • the problem is that the structure of the electrode material collapses, the organic carbonate is easily oxidized and decomposed, gas is generated, and the internal pressure of the battery increases, resulting in a rapid decline in electrical performance. Therefore, research and preparation of lithium-ion electrolytes capable of withstanding high voltages is of great significance for the development of high-energy-density batteries.
  • the present application aims to provide an electrolyte and an electrochemical device containing the electrolyte to solve the problems of cycling and high-temperature storage of high-voltage lithium-ion batteries.
  • the electrolyte provided by the present application can significantly improve the high-temperature cycle and high-temperature storage performance of high-voltage batteries.
  • the application provides an electrolyte comprising a compound of formula I,
  • R 1 , R 2 and R 3 are each independently selected from hydrogen, halogen, substituted or unsubstituted alkyl, substituted or unsubstituted alkenyl, substituted or unsubstituted alkynyl and substituted or unsubstituted alkynyl A heteroatom-containing group; wherein, when substituted, the substituent is selected from halogen; the heteroatom includes at least one of O, S, P, N, Si and B; at least one of R 1 , R 2 and R 3 One has an unsaturated functional group.
  • the unsaturated functional group includes at least one of a carbon-carbon double bond and a carbon-carbon triple bond.
  • R 1 , R 2 and R 3 are each independently selected from hydrogen, halogen, substituted or unsubstituted C 1 -C 10 alkyl, substituted or unsubstituted C 2 - C 10 alkenyl, substituted or unsubstituted C 2 -C 10 alkynyl, and substituted or unsubstituted C 1 -C 10 heteroatom-containing groups.
  • the heteroatom-containing group includes an ester group, a ketone group, an aldehyde group, an amino group, an amine group, a boronate group, an alkoxy group, a thiol group and a cyano group.
  • the compound shown in formula I is selected from one or more of the following compounds:
  • the mass percentage of the compound of formula I is 0.01% to 2%.
  • the electrolyte further includes at least one of a polynitrile compound, a sulfonic acid ester compound and a boron-containing lithium salt compound with a number of cyano groups ⁇ 2.
  • the mass percentage content of the polynitrile compound with the number of cyano groups ⁇ 2 is 0.10%-15%.
  • the mass percentage of the sulfonic acid ester compound is 0.10%-10%.
  • the mass percentage of the boron-containing lithium salt compound is 0.01% to 5%.
  • the polynitrile compound with the number of cyano groups ⁇ 2 comprises at least one of the compounds represented by formula (II) to formula (V):
  • R 21 is selected from substituted or unsubstituted C 1 -C 12 alkylene, substituted or unsubstituted C 1 -C 12 alkyleneoxy;
  • R 3 and R 32 are each independently selected from single bond or substituted or Unsubstituted C 1 -C 12 alkylene;
  • R4 1 , R 42 and R 43 are each independently selected from single bond, substituted or unsubstituted C 1 -C 12 alkylene, substituted or unsubstituted C 1 -C C 12 alkyleneoxy;
  • R 51 is selected from substituted or unsubstituted C 1 -C 12 alkylene, substituted or unsubstituted C 2 -C 12 alkenylene, substituted or unsubstituted C 6 -C 26 alkylene
  • Aryl substituted or unsubstituted C 2 -C 12 heterocyclic group; wherein when substituted, the substituent is a halogen atom.
  • the polynitrile compound with the number of cyano groups ⁇ 2 includes at least one of the following substances:
  • the sulfonic acid lipid compound is selected from cyclic sulfonic acid ester compounds, and the cyclic sulfonic acid ester compound comprises a cyclic monosulfonic acid ester and a cyclic disulfonic acid ester. one or more.
  • the sulfonate compound comprises at least one of the compounds represented by formula VI:
  • a and B each independently represent an alkylene group or a fluoroalkylene group, and L represents a single bond or a -OSO 2 - group.
  • a and B each independently represent a C 1 -C 8 alkylene group or a C 1 -C 8 fluoroalkylene group.
  • the compound represented by formula VI includes a cyclic monosulfonate compound represented by formula VI-1:
  • R 611 and R 612 each independently represent a hydrogen atom, a fluorine atom or a C 1 -C 4 alkyl group, and n is 1, 2, 3 or 4;
  • the compound represented by formula VI includes a cyclic disulfonate compound represented by the following formula VI-2.
  • R 621 and R 622 each independently represent an atom, a fluorine atom or a C 1 -C 4 alkyl group, and n is 1, 2, 3 or 4, and if n is 2 or more, a plurality of R 623 may be the same as each other or different, and the plurality of R624s may be the same or different from each other.
  • the cyclic sulfonate includes 1,3-propane sultone, 1,2-propane sultone, 1,4-butane sultone, 1,2-butane sultone, 1,3-butane sultone, 2,4-butane sultone, 1,3-pentane sultone, methylene methanedisulfonate At least one of ester and ethylene methane disulfonate.
  • the boron-containing lithium salt compound includes a compound represented by formula VII:
  • M + represents an alkali metal cation
  • the electrolyte further includes a cyclic carbonate compound.
  • the cyclic carbonate includes at least one of fluorinated cyclic carbonate and/or unsaturated cyclic carbonate.
  • the fluorinated cyclic carbonate includes a fluoride of a cyclic carbonate having an alkylene group of 2-6 carbon atoms.
  • the fluorocyclic carbonate includes fluoroethylene carbonate, 4,4-difluoroethylene carbonate, 4,5-difluoroethylene carbonate, 4-fluoro- 4-Methylethylene carbonate, 4,5-difluoro-4-methylethylene carbonate, 4-fluoro-5-methylethylene carbonate, 4,4-difluoro-5-methylcarbonate Ethylene, 4-(fluoromethyl)-ethylene carbonate, 4-(difluoromethyl)-ethylene carbonate, 4-(trifluoromethyl)-ethylene carbonate, 4-(fluoromethyl) base)-4-fluoroethylene carbonate, 4-(fluoromethyl)-5-fluoroethylene carbonate, 4-fluoro-4,5-dimethylethylene carbonate, 4,5-difluoro- At least one of 4,5-dimethylethylene carbonate and 4,4-difluoro-5,5-dimethylethylene carbonate.
  • the present application further provides an electrochemical device comprising a positive electrode, a negative electrode and the electrolyte according to the present application.
  • the positive electrode includes a current collector, and an active material layer and an insulating layer disposed on the surface of the current collector.
  • the present application further provides an electronic device comprising the electrochemical device described in the second aspect of the present application.
  • the electrolyte solution and the electrochemical device comprising the electrolyte solution provided by the present application can significantly improve the high-temperature cycle and high-temperature storage performance of high-voltage batteries.
  • 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).
  • any lower limit can be combined with any upper limit to form an unspecified range; and any lower limit can be combined with any other lower limit to form an unspecified range, and likewise any upper limit can be combined with any other upper limit to form an unspecified range.
  • each individually disclosed point or single value may itself serve as a lower or upper limit in combination with any other point or single value or with other lower or upper limits to form a range that is not expressly recited.
  • 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%.
  • hydrocarbyl encompasses alkyl, alkenyl, alkynyl.
  • 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. When specifying an alkyl group having a specific carbon number, it is intended to encompass all geometric isomers having that carbon number; thus, for example, “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.
  • alkenyl refers to a monovalent unsaturated hydrocarbon radical 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 groups generally contain from 2 to 20 carbon atoms and include, for example, -C2-4 alkenyl, -C2-6 alkenyl, and -C2-10 alkenyl. Representative alkenyl groups include, for example, vinyl, n-propenyl, isopropenyl, n-but-2-enyl, but-3-enyl, n-hex-3-enyl, and the like.
  • alkynyl refers to a monovalent unsaturated hydrocarbon group which may be straight or branched and having at least one and usually one, two or three carbon-carbon triple bonds. Unless otherwise defined, the alkynyl groups generally contain from 2 to 20 carbon atoms and include, for example, -C2-4alkynyl, -C3-6alkynyl, and -C3-10alkynyl. Representative alkynyl groups include, for example, ethynyl, prop-2-ynyl (n-propynyl), n-but-2-ynyl, n-hex-3-ynyl, and the like.
  • alkylene means a divalent saturated hydrocarbon group which may be straight or branched. Unless otherwise defined, the alkylene groups generally contain from 2 to 10 carbon atoms and include, for example, -C2-3alkylene and -C2-6alkylene-. 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.
  • each component is based on the total weight of the electrolyte.
  • the application provides an electrolyte solution comprising a compound of formula I.
  • compounds of formula I can improve high temperature cycling and high temperature storage properties. This is because the non-shared electron pair on N in the compound of formula I can stabilize the anion of the salt in the electrolyte, sulfur can react with active oxygen, inhibit the decomposition of the electrolyte, form a sulfur-rich interface film, and improve the interface The mechanical stability of the film improves the cycle performance; in addition, the compound of formula I has a low oxidation potential, and can preferentially form a solid electrolyte phase interface film (ie, CEI film) on the surface of the positive electrode to protect the positive electrode and reduce the contact between the positive electrode material and the electrolyte. Induced chemical outgassing, which in turn improves cycling and high temperature storage performance. At the same time, the compound of formula I can widen the oxidation window of the solvent, improve the oxidation resistance of the solvent, and improve the high temperature performance.
  • CEI film solid electrolyte phase interface film
  • R 1 , R 2 and R 3 are each independently selected from hydrogen, halogen, substituted or unsubstituted alkyl, substituted or unsubstituted alkenyl, substituted or unsubstituted alkynyl and substituted or unsubstituted alkynyl A heteroatom-containing group; wherein, when substituted, the substituent is selected from halogen; the heteroatom includes at least one of O, S, P, N, Si and B; at least one of R 1 , R 2 and R 3 One has an unsaturated functional group.
  • R 1 has an unsaturated functional group.
  • R 2 has an unsaturated functional group.
  • R 3 has an unsaturated functional group.
  • the unsaturated functional group is selected from carbon-carbon double bonds and carbon-carbon triple bonds. In some embodiments, the unsaturated functional group is a carbon-carbon double bond. In some embodiments, the unsaturated functional group is a carbon-carbon triple bond.
  • R 1 , R 2 and R 3 are each independently selected from hydrogen, halogen, substituted or unsubstituted C 1 -C 10 alkyl, substituted or unsubstituted C 2 - C 10 alkenyl, substituted or unsubstituted C 2 -C 10 alkynyl, and substituted or unsubstituted C 1 -C 10 heteroatom-containing groups.
  • the heteroatom-containing group includes an ester group, a ketone group, an aldehyde group, an amino group, an amine group, a boronate group, an alkoxy group, a thiol group and a cyano group.
  • the compound shown in formula I includes at least one of the following compounds:
  • the mass percentage of the compound of formula I is 0.01% to 2%. According to some embodiments of the present application, the mass percentage of the compound of formula I in the electrolyte is 0.1% to 1.5%. According to some preferred embodiments of the present application, the mass percentage of the compound of formula I in the electrolyte is 0.3% to 1.0%.
  • the electrolyte may further include additives.
  • the additive includes at least one of polynitrile compounds with a number of nitriles ⁇ 2, sulfonate compounds, cyclic carbonate compounds, and boron-containing lithium salt compounds.
  • the electrolyte may further comprise polynitrile compounds with a number of nitriles ⁇ 2, and the mass percentage of the polynitrile compounds with a number of nitriles ⁇ 2 in the electrolyte is: 0.10%-15%.
  • the polynitrile compound with the number of cyano groups ⁇ 2 comprises at least one of the compounds represented by formula (II) to formula (V):
  • R 21 is selected from substituted or unsubstituted C 1 -C 12 alkylene, substituted or unsubstituted C 1 -C 12 alkyleneoxy;
  • R 31 and R 32 are each independently selected from single bond or substituted or Unsubstituted C 1 -C 12 alkylene;
  • R 41 , R 42 and R4 3 are each independently selected from single bond, substituted or unsubstituted C 1 -C 12 alkylene, substituted or unsubstituted C 1 -C C 12 alkyleneoxy;
  • R 51 is selected from substituted or unsubstituted C 1 -C 12 alkylene, substituted or unsubstituted C 2 -C 12 alkenylene, substituted or unsubstituted C 6 -C 26 alkylene
  • Aryl substituted or unsubstituted C 2 -C 12 heterocyclic group; wherein when substituted, the substituent is a halogen atom.
  • the polynitrile compound with the number of cyano groups ⁇ 2 includes at least one of the following substances:
  • the electrolyte solution may further comprise a sulfonate compound.
  • the mass percentage of the sulfonate compound in the electrolyte is: 0.10%-10%.
  • the sulfonic acid ester compound comprises one or more of cyclic monosulfonic acid ester and cyclic disulfonic acid ester.
  • the sulfonate compound comprises at least one of the compounds represented by formula VI:
  • a and B each independently represent an alkylene group or a fluoroalkylene group
  • L represents a single bond or a -OSO 2 - group.
  • the number of carbon atoms of the alkylene group is 1-8, preferably 1-6, and more preferably 1-4.
  • a fluoroalkylene group means that at least one hydrogen atom of an unsubstituted alkylene group is substituted with a fluorine atom.
  • the number of carbon atoms of the fluorinated alkylene group is, for example, 1-8, preferably 1-6, and more preferably 1-4.
  • the -OSO 2 - group may be in any orientation.
  • the cyclic sulfonic acid ester is a cyclic monosulfonic acid ester
  • the cyclic monosulfonic acid ester is a compound represented by the following formula VI-1.
  • R 611 and R 612 each independently represent a hydrogen atom, a fluorine atom or an alkyl group having 1 to 4 carbon atoms, and n is 1, 2, 3 or 4.
  • the cyclic sulfonate is a cyclic disulfonate, and the cyclic disulfonate is preferably a compound represented by the following formula VI-2.
  • R 621 and R 622 each independently represent a hydrogen atom, a fluorine atom or an alkyl group having 1 to 4 carbon atoms, and n is 1, 2, 3 or 4, and if n is 2 or more, a plurality of R 623 may be the same or different from each other, and a plurality of R 624 may be the same or different from each other.
  • cyclic sulfonates include monosulfonates (when X in formula VI is a single bond) such as 1,3-propane sultone, 1,2-propane sultone, 1,4- Butane sultone, 1,2-butane sultone, 1,3-butane sultone, 2,4-butane sultone, 1,3-pentane sultone and disulfonates (when X in formula VI is an -OSO2- group) such as methylene methane disulfonate and ethylene methane disulfonate.
  • 1,3-propane sultone (PS), 1,4-butane sultone (BS), and methanedisulfonic acid are preferred in view of the effect of forming a film, ease of availability, and cost Methylene (MMDS).
  • the cyclic disulfonate has the property of easily forming a film with excellent quality on the negative electrode.
  • cyclic sulfonate compound can improve the lithium ion and further improve the high temperature cycle and high temperature storage performance of lithium ion battery, and can further improve the floating charge performance; this is because the cyclic sulfate compound has both positive and negative electrodes It can form an interface film with excellent mechanical stability, which can significantly inhibit the side reactions of the positive and negative interfaces, further improve the thermal and mechanical stability of the interface film, and improve the cycle performance and high-temperature storage performance;
  • the sulfonic acid ester has the property of easily forming a film with excellent quality on the negative electrode, and it can be used in combination with the cyclic monosulfonic acid ester to achieve more excellent improvement.
  • the electrolyte solution may further comprise a cyclic carbonate compound in a mass percentage of 0.01% to 10% in the electrolyte solution.
  • the cyclic carbonate compound includes at least one of fluorinated cyclic carbonate and/or unsaturated cyclic carbonate.
  • the fluorinated cyclic carbonate is selected from fluorides of cyclic carbonates having alkylene groups of 2-6 carbon atoms.
  • fluorocyclic carbonate examples include, but are not limited to, fluoroethylene carbonate, 4,4-difluoroethylene carbonate, 4,5-difluoroethylene carbonate, 4-fluoro-4 - Methylethylene carbonate, 4,5-difluoro-4-methylethylene carbonate, 4-fluoro-5-methylethylene carbonate, 4,4-difluoro-5-methylethylene carbonate Ethyl ester, 4-(fluoromethyl)-ethylene carbonate, 4-(difluoromethyl)-ethylene carbonate, 4-(trifluoromethyl)-ethylene carbonate, 4-(fluoromethyl) )-4-fluoroethylene carbonate, 4-(fluoromethyl)-5-fluoroethylene carbonate, 4-fluoro-4,5-dimethylethylene carbonate, 4,5-difluoro-4 , 5-dimethylethylene carbonate and 4,4-difluoro-5,5-dimethylethylene carbonate.
  • the electrolyte solution may further include a boron-containing lithium salt compound, preferably a metal tetraborate compound.
  • a boron-containing lithium salt compound preferably a metal tetraborate compound.
  • the content of the boron-containing lithium salt compound is 0.01 wt % to 1 wt % based on the total weight of the electrolyte.
  • the boron-containing lithium salt compound is a metal tetraborate compound, which can be specifically selected from the compounds shown in formula VII:
  • M + represents an alkali metal cation.
  • alkali metal cations include, but are not limited to, lithium ions, sodium ions, potassium ions, cesium ions.
  • the compound of formula VII is selected from one or more of the following compounds:
  • the electrolyte may further include fluorinated pyridine, such as difluoropyridine, pentafluoropyridine, and the like.
  • the electrolyte lithium salt used in the electrolyte of the present application is selected from one or more of inorganic lithium salts and organic lithium salts.
  • the lithium salt is selected from lithium hexafluorophosphate (LiPF 6 ), lithium tetrafluoroborate (LiBF4), lithium bisfluorosulfonimide (LiFSI), lithium bistrifluoromethanesulfonimide (LiTFSI) ), one or more of lithium difluorophosphate (LiPO 2 F 2 ), further preferably, the lithium salt is selected from lithium hexafluorophosphate (LiPF 6 ).
  • the solvent used in the electrolytic solution of the present application may be any non-aqueous solvent known in the prior art that can be used as a solvent of the electrolytic solution.
  • the non-aqueous solvent includes, but is not limited to, cyclic carbonate, chain carbonate, cyclic carboxylate, chain carboxylate, cyclic ether, chain ether, phosphorus-containing Organic solvents, sulfur-containing organic solvents and aromatic fluorinated solvents.
  • cyclic carbonates include, but are not limited to, ethylene carbonate (EC), propylene carbonate (PC), and butylene carbonate.
  • the cyclic carbonate has 3-6 carbon atoms.
  • the chain carbonate includes, but is not limited to, dimethyl carbonate, ethyl methyl carbonate, diethyl carbonate (DEC), methyl n-propyl carbonate, ethyl carbonate n-propyl carbonate, di-n-propyl carbonate and other chain carbonates, as chain carbonates substituted by fluorine, such as bis(fluoromethyl)carbonate, bis(difluoromethyl)carbonate, bis(trifluoromethyl)carbonate Fluoromethyl)carbonate, bis(2-fluoroethyl)carbonate, bis(2,2-difluoroethyl)carbonate, bis(2,2,2-trifluoroethyl)carbonate, 2- Fluoroethylmethylcarbonate, 2,2-difluoroethylmethylcarbonate and 2,2,2-trifluoroethylmethylcarbonate.
  • fluorine such as bis(fluoromethyl)carbonate, bis(difluoromethyl)carbonate, bis(tri
  • cyclic carboxylic acid esters include, but are not limited to, gamma-butyrolactone and gamma-valerolactone.
  • some of the hydrogen atoms of the cyclic carboxylate may be replaced by fluorine.
  • the chain carboxylates include, but are not limited to, methyl acetate, ethyl acetate, propyl acetate, isopropyl acetate, butyl acetate, sec-butyl acetate, isobutyl acetate , tert-butyl acetate, methyl propionate, ethyl propionate, propyl propionate, isopropyl propionate, methyl butyrate, ethyl butyrate, propyl butyrate, methyl isobutyrate, isobutyl Ethyl valerate, methyl valerate, ethyl valerate, methyl pivalate and ethyl pivalate.
  • fluorine-substituted chain carboxylates include, but are not limited to, methyl trifluoroacetate, ethyl trifluoroacetate, propyl trifluoroacetate, butyl trifluoroacetate, and 2,2 trifluoroacetate , 2-trifluoroethyl ester.
  • cyclic ethers include, but are not limited to, tetrahydrofuran, 2-methyltetrahydrofuran, 1,3-dioxolane, 2-methyl 1,3-dioxolane, 4- Methyl 1,3-dioxolane, 1,3-dioxane, 1,4-dioxane and dimethoxypropane.
  • the chain ethers include, but are not limited to, dimethoxymethane, 1,1-dimethoxyethane, 1,2-dimethoxyethane, diethoxy Methane, 1,1-diethoxyethane, 1,2-diethoxyethane, ethoxymethoxymethane, 1,1-ethoxymethoxyethane and 1,2-ethane Oxymethoxyethane.
  • the phosphorus-containing organic solvent includes, but is not limited to, trimethyl phosphate, triethyl phosphate, dimethyl ethyl phosphate, methyl diethyl phosphate, ethylene methyl phosphate, Ethylene Ethyl Phosphate, Triphenyl Phosphate, Trimethyl Phosphite, Triethyl Phosphite, Triphenyl Phosphite, Tris(2,2,2-trifluoroethyl) Phosphate, and Tris(2-Tris(2) Phosphate) , 2,3,3,3-pentafluoropropyl) ester.
  • the sulfur-containing organic solvent includes, but is not limited to, sulfolane, 2-methyl sulfolane, 3-methyl sulfolane, dimethyl sulfone, diethyl sulfone, ethyl methyl sulfone, methyl sulfone propyl sulfone, dimethyl sulfoxide, methyl methanesulfonate, ethyl methanesulfonate, methyl ethanesulfonate, ethyl ethanesulfonate, dimethyl sulfate, diethyl sulfate, and dibutyl sulfate.
  • some of the hydrogen atoms of the sulfur-containing organic solvent may be replaced by fluorine.
  • the aromatic fluorine-containing solvent includes, but is not limited to, fluorobenzene, difluorobenzene, trifluorobenzene, tetrafluorobenzene, pentafluorobenzene, hexafluorobenzene, and trifluoromethylbenzene.
  • the solvent used in the electrolyte solution of the present application includes one or more of the above.
  • the solvent used in the electrolyte of the present application is selected from the group consisting of cyclic carbonate, chain carbonate, cyclic carboxylate, chain carboxylate, and combinations thereof.
  • the solvent used in the electrolyte of the present application comprises an organic solvent selected from the group consisting of: ethylene carbonate, propylene carbonate, diethyl carbonate, ethyl propionate, propionic acid Propyl ester, n-propyl acetate, ethyl acetate, and combinations thereof.
  • the solvent used in the electrolyte of the present application is selected from the group consisting of: ethylene carbonate, propylene carbonate, diethyl carbonate, ethyl propionate, propyl propionate, ⁇ -butyrolactone, and combinations thereof.
  • the solvent used in the electrolyte of the present application is a combination of ethylene carbonate, propylene carbonate, and diethyl carbonate.
  • the electrochemical device of the present application refers to any device capable of generating an electrochemical reaction, and specific examples thereof include all kinds of primary batteries, secondary batteries, fuel cells, solar cells, or capacitors.
  • the electrochemical device is a lithium secondary battery, including a lithium metal secondary battery, a lithium ion secondary battery, a lithium polymer secondary battery, or a lithium ion polymer secondary battery.
  • the electrochemical device of the present application includes a positive electrode having a positive electrode active material capable of occluding and releasing metal ions; a negative electrode having a negative electrode active material capable of absorbing and releasing metal ions; and the electrolyte of the present application.
  • the electrolyte used in the lithium-ion battery of the present application is any of the above-mentioned electrolytes of the present application.
  • the electrolytic solution used in the lithium ion battery of the present application may contain other electrolytic solutions within a range that does not deviate from the gist of the present application.
  • the negative electrode of the electrochemical device includes a current collector and a negative electrode active material layer formed on the current collector, the negative electrode active material layer includes a negative electrode active material, and the negative electrode active material may include a reversible intercalation/deintercalation lithium ion Materials, lithium metal, lithium metal alloys, materials capable of doping/de-doping lithium, or transition metal oxides such as Si, SiOx, etc.
  • the material that reversibly intercalates/deintercalates lithium ions may be a carbon material.
  • the carbon material may be any carbon-based negative active material commonly used in lithium-ion rechargeable electrochemical devices. Examples of carbon materials include crystalline carbon, amorphous carbon, and combinations thereof.
  • Crystalline carbon can be amorphous or plate-shaped, platelet-shaped, spherical or fibrous natural graphite or artificial graphite.
  • the amorphous carbon can be soft carbon, hard carbon, mesophase pitch carbonization product, fired coke, and the like. Both low-crystalline carbon and high-crystalline carbon can be used as the carbon material.
  • soft carbon and hard carbon can be generally included.
  • highly crystalline carbon material natural graphite, crystalline graphite, pyrolytic carbon, mesophase pitch-based carbon fibers, mesophase carbon microbeads, mesophase pitch, and high temperature calcined carbon (such as petroleum or coke derived from coal tar pitch may be generally included) ).
  • the negative electrode active material layer contains a binder
  • the binder may include various binder polymers, such as vinylidene fluoride-hexafluoropropylene copolymer (PVDF-co-HFP), polyvinylidene fluoride, polyvinylidene Acrylonitrile, polymethyl methacrylate, polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, ethylene oxide-containing polymers, Polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyethylene, polypropylene, styrene-butadiene rubber, acrylic (esterified) styrene-butadiene rubber, epoxy resin, nylon, etc., but not limited thereto.
  • PVDF-co-HFP vinylidene fluoride-hexafluoropropylene copolymer
  • the negative electrode active material layer also includes a conductive material to improve electrode conductivity.
  • Any conductive material can be used as the conductive material as long as it does not cause chemical change.
  • Examples of conductive materials include: carbon-based materials such as natural graphite, artificial graphite, carbon black, acetylene black, ketjen black, carbon fibers, etc.; metal-based materials such as metal powders or metal fibers including copper, nickel, aluminum, silver, etc. ; Conductive polymers, such as polyphenylene derivatives, etc.; or their mixtures.
  • the current collector may be copper foil, nickel foil, stainless steel foil, titanium foil, nickel foam, copper foam, a polymer substrate coated with conductive metal, or a combination thereof.
  • the positive electrode in the electrochemical device of the present application includes a current collector, and an active material layer and an insulating layer disposed on the surface of the current collector.
  • the positive electrode comprises: a positive electrode current collector, the fluid may be Al, but not limited thereto; a positive electrode active material layer; and an insulating layer, the insulating layer is disposed on the positive electrode current collector.
  • the insulating layer satisfies at least one of the conditions (a) to (c): (a) there is a gap between the insulating layer and the positive electrode active material layer, and the width of the gap is 0 mm to 2 mm; (b) the insulating layer includes inorganic particles, the inorganic particles include aluminum oxide, silicon dioxide, magnesium oxide, titanium oxide, hafnium dioxide, tin oxide, ceria, nickel oxide, zinc oxide, calcium oxide , at least one of zirconium dioxide, yttrium oxide, silicon carbide, boehmite, aluminum hydroxide, magnesium hydroxide, calcium hydroxide or barium sulfate; (c) the insulating layer comprises a polymer, the polymer Including homopolymer of vinylidene fluoride, copolymer of vinylidene fluoride, copolymer of hexafluoropropylene, polystyrene, polyphenylene vinylene, sodium polyvinate
  • the material composition of the positive electrode used in the electrochemical device of the present application and the manufacturing method thereof may include any of the techniques disclosed in the prior art.
  • the positive active material includes, but is not limited to, sulfides, phosphate compounds, and lithium transition metal composite oxides. In some embodiments, the positive active material includes a lithium transition metal-based compound having a structure capable of extracting and inserting lithium ions.
  • the positive electrode comprises any of the compositions disclosed in the prior art.
  • the positive electrode is made by forming a positive electrode material on a current collector with a positive electrode active material layer including a lithium transition metal-based compound powder and a binder.
  • the positive electrode active material layer is usually fabricated by the following operations: dry mixing the positive electrode material and a binder (a conductive material and a thickener, etc. can be used as needed) to form a sheet, and the resulting The sheet is press-bonded to the positive electrode current collector, or these materials are dissolved or dispersed in a liquid medium to prepare a slurry, and the slurry is applied on the positive electrode current collector and dried.
  • the positive active material layer includes any material disclosed in the prior art.
  • the electrochemical devices of the present application are provided with a separator between the positive electrode and the negative electrode to prevent short circuits.
  • the material and shape of the separator used in the electrochemical device of the present application are not particularly limited, and it may be any technique disclosed in the prior art.
  • the separator includes a polymer or inorganic or the like formed from a material that is stable to the electrolyte of the present application.
  • the separator may include a substrate layer and a surface treatment layer.
  • the base material layer is a non-woven fabric, film or composite film with a porous structure, and the material of the base material layer is selected from at least one of polyethylene, polypropylene, polyethylene terephthalate and polyimide.
  • a polypropylene porous membrane, a polyethylene porous membrane, a polypropylene non-woven fabric, a polyethylene non-woven fabric or a polypropylene-polyethylene-polypropylene porous composite membrane can be selected.
  • At least one surface of the base material layer is provided with a surface treatment layer, and the surface treatment layer may be a polymer layer or an inorganic material layer, or a layer formed by mixing a polymer and an inorganic material.
  • the inorganic layer includes inorganic particles and a binder, and the inorganic particles are selected from aluminum oxide, silicon oxide, magnesium oxide, titanium oxide, hafnium oxide, tin oxide, ceria, nickel oxide, zinc oxide, calcium oxide, zirconium oxide, One or a combination of yttrium oxide, silicon carbide, boehmite, aluminum hydroxide, magnesium hydroxide, calcium hydroxide and barium sulfate.
  • the binder is selected from polyvinylidene fluoride, vinylidene fluoride-hexafluoropropylene copolymer, polyamide, polyacrylonitrile, polyacrylate, polyacrylic acid, polyacrylate, polyvinylpyrrolidone, polyvinylalkoxy , one or a combination of polymethyl methacrylate, polytetrafluoroethylene and polyhexafluoropropylene.
  • the polymer layer contains a polymer, and the material of the polymer is selected from polyamide, polyacrylonitrile, acrylate polymer, polyacrylic acid, polyacrylate, polyvinylpyrrolidone, polyvinylalkoxy, polyvinylidene fluoride, At least one of poly(vinylidene fluoride-hexafluoropropylene).
  • the electrolyte solution according to the present application can suppress an increase in the direct current internal resistance of the electrochemical device, so that the electrochemical device thus manufactured is suitable for electronic equipment or devices in various fields.
  • electronic devices of the present application 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, headsets , VCR, LCD TV, Portable Cleaner, Portable CD Player, Mini Disc, Transceiver, Electronic Notepad, Calculator, Memory Card, Portable Recorder, Radio, Backup Power, Motor, Automobile, Motorcycle, Power-assisted Bicycle, Bicycle , lighting equipment, toys, game consoles, clocks, power tools, flashes, cameras, large household batteries and lithium-ion capacitors, etc.
  • the positive active material LCO molecular formula is LiCoO 2
  • conductive carbon black conductive carbon black
  • binder polyvinylidene fluoride abbreviated as PVDF
  • NMP N- Methylpyrrolidone
  • negative pole piece the negative electrode active material graphite, binder styrene-butadiene rubber (abbreviated as SBR), thickener sodium carboxymethyl cellulose (abbreviated as CMC) according to the weight ratio of 97.7: 1.3: 1.0 in an appropriate amount.
  • SBR binder styrene-butadiene rubber
  • CMC thickener sodium carboxymethyl cellulose
  • Preparation of lithium ion battery stack the positive pole piece, the separator and the negative pole piece in order, so that the separator is placed between the positive pole piece and the negative pole piece to play a role of isolation, and then roll to obtain a bare cell;
  • the battery is placed in the outer packaging foil, the electrolyte prepared above is injected into the dried battery, and the preparation of the lithium ion battery is completed after vacuum packaging, standing, forming, shaping and other processes.
  • Thickness expansion ratio (H12-H11)/H11 ⁇ 100%
  • the lithium-ion battery was placed in a 45°C incubator for 30 minutes to allow the lithium-ion battery to reach a constant temperature.
  • the lithium-ion battery that has reached a constant temperature is charged to 4.5V at a constant current of 0.2C at 45°C, charged to a constant voltage of 0.05C at 4.5V, left for 5 minutes, and then discharged to 3.0V at a constant current of 0.2C, and left for 5 minutes.
  • Capacity retention rate (%) of lithium ion battery after N cycles discharge capacity at Nth cycle/discharge capacity at 1st cycle ⁇ 100%.
  • the lithium-ion battery was charged to 4.5V with a constant current of 0.7C and a constant voltage of 4.5V to a current of 0.05C.
  • the battery was placed in a high temperature box, heated to 135 °C with a temperature rise rate of 5 ⁇ 2 °C/min, and then kept for 1 h, and the voltage, temperature and temperature of the hot box were recorded. The test is passed if the battery does not catch fire, explode, or emit smoke. Test 10 batteries in each group, and record the number of batteries that pass the test.
  • Thickness expansion ratio (D 12 -D 11 )/D 11 ⁇ 100%.
  • the compound of formula I can improve high-temperature cycling and high-temperature storage performance, because the non-shared electron pair of N in compound I can make the anion of the salt in the electrolyte tend to Stabilized, and the unsaturated functional group included in the special formula I compound can be reduced on the negative electrode surface to form a stable ion conductive film; at the same time, the oxidation potential of the formula I compound is low, which can preferentially form a solid electrolyte phase on the positive electrode surface.
  • the interface film protects the positive electrode, reduces the chemical gas production caused by the contact between the positive electrode material and the electrolyte, and then improves the cycle and high-temperature storage performance; by comparing Example 3 and Comparative Example 3, it can be seen that the introduction of unsaturated bonds can The cycling performance and the high-temperature storage thickness expansion ratio are further improved, because the introduction of unsaturated functional groups can preferentially reduce the form-stable SEI film at the anode, suppressing the side reaction between the electrolyte and the electrode interface, thereby improving the cycling performance and high-temperature storage performance.
  • the amount of the compound of formula I is reduced by introducing polynitriles in combination with the compound of formula I; the combination of the two improves the thermal and mechanical stability of the interface film and improves the cycle performance. and high temperature storage performance and safety performance.
  • Table 2 shows the effect of cyclic sulfonate additives on battery performance.
  • the DCR and high-temperature storage properties of the electrolyte containing tetraborate compounds are significantly improved, because the tetraborate compounds can form dense and stable negative electrodes.
  • the interface film formed has high ionic conductivity and strong electronic insulation, which significantly improves the interface impedance and reduces DCR; it cooperates with the above structural additives to form an organic-inorganic interface film, reducing the interface film.
  • the impedance simultaneously improves the mechanical strength of the interfacial film, showing high thermal and chemical stability.
  • Table 4 shows the effect of the cathode insulating coating on the battery performance.
  • the insulating coatings in Examples 30 and 31 are located between two adjacent first surface positive electrode active material layers, there is a 1 mm gap between the two ends of the insulating layer and the first surface active material layer, and the insulating layer is composed of aluminum oxide. , the thickness is 10um.
  • the presence of the insulating coating 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 coating 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. By reducing the exposure of the substrate, the production may be reduced to a certain extent. Heat increases the throughput of the hot box.

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Abstract

本申请涉及一种电解液和包含该电解液的电化学装置以及电子装置。所述电解液包括式（I）化合物，式（I）中，R1、R2和R3各自独立地选自氢、卤素、取代或未取代的烷基、取代或未取代的烯基、取代或未取代的炔基和取代或未取代的含杂原子基团；其中，经取代时，取代基选自卤素；所述杂原子包括O、S、P、N、Si和B中的至少一种；R1、R2和R3中至少一个具有不饱和官能团。本申请的电解液能够改善高电压电池高温循环和高温存储性能。

Description

一种电解液及包含该电解液的电化学装置和电子装置 技术领域
本申请涉及储能技术领域，尤其涉及一种电解液和包含该电解液的电化学装置和电子装置。
背景技术
锂离子电池因其具有能量密度高、循环寿命长、自放电率低、无记忆效应、放电电压稳定、充放电快速和环保等优点，如今成为3C便携式电子设备的主要单元。然而，随着社会的发展，对锂离子电池的要求越来越高，比如高能量密度、快速充电成为许多科研机构和电池公司研究的主要方向。
因锂电池所能提供的功率和能量与工作电压成正比，所以为了解决上述问题，提高电池的电压是最简单最直接的方法。但是提高工作电压，面临的问题就是电极材料结构坍塌，有机碳酸酯容易被氧化分解，产生气体，电池内部压力增大，导致电性能快速衰退。因此，研究制备能够耐受高电压的锂离子电解质对于发展高能量密度电池具有极其重要的意义。
发明内容
本申请旨在提供一种电解液和包含该电解液的电化学装置以解决高电压锂离子电池的循环和高温存储问题。本申请提供的电解液能够显著改善高电压电池高温循环、高温存储性能。
在本申请的第一方面，本申请提供了一种电解液，其包括式I化合物，
Figure PCTCN2020133988-appb-000001
式I中，R 1、R 2和R 3各自独立地选自氢、卤素、取代或未取代的烷基、取代或未取代的烯基、取代或未取代的炔基和取代或未取代的含杂原子基团；其中，经取代时，取代基选自卤素；所述杂原子包括O、S、P、N、Si和B中的至少一种；R 1、R 2和R 3中至少 一个具有不饱和官能团。
根据本申请的一些实施方式，所述不饱和官能团包括碳碳双键、碳碳三键中的至少一种。
根据本申请的一些实施方式，式I中，R 1、R 2和R 3各自独立地选自氢、卤素、取代或未取代的C 1-C 10烷基、取代或未取代的C 2-C 10烯基、取代或未取代的C 2-C 10炔基和取代或未取代的C 1-C 10含杂原子基团。
根据本申请的一些实施方式，式I中，所述含杂原子基团包括酯基、酮基、醛基、氨基、胺基、硼酸酯基、烷氧基、硫醇基和氰基。
根据本申请的一些进一步优选的实施方式，式I所示化合物选自如下化合物中的一种或多种：
Figure PCTCN2020133988-appb-000002
根据本申请的一些实施方式，基于所述电解液的质量，所述式I化合物的质量百分数为0.01％～2％。
根据本申请的一些实施方式，所述电解液进一步还包括氰基数量≥2的多腈化合物、磺酸酯类化合物和含硼锂盐化合物中的至少一种。
根据本申请的一些实施方式，基于所述电解液的质量，所述氰基数量≥2的多腈化合物的质量百分含量为0.10％-15％。
根据本申请的一些实施方式，基于所述电解液的质量，所述磺酸酯类化合物的质量百分含量为0.10％-10％。
根据本申请的一些实施方式，基于所述电解液的质量，所述含硼锂盐化合物的质量百分数为0.01％至5％。
根据本申请的一些优选实施方式，所述氰基数量≥2的多腈化合物包含式(II)至式(V)所示的化合物中的至少一种：
N≡C-R 21-C≡N
式(II)
Figure PCTCN2020133988-appb-000003
其中，R 21选自取代或未取代的C 1～C 12亚烷基、取代或未取代的C 1～C 12亚烷氧基；R 3和R 32各自独立地选自单键或取代或未取代的C 1～C 12亚烷基；R4 1、R 42和R 43各自独立地选自单键、取代或未取代的C 1～C 12亚烷基、取代或未取代的C 1～C 12亚烷氧基；R 51选自取代或未取代的C 1～C 12亚烷基、取代或未取代的C 2～C 12亚烯基、取代或未取代的C 6～C 26亚芳基、取代或未取代的C 2-C 12亚杂环基团；其中经取代时，取代基为卤素原子。
根据本申请的一些进一步的优选实施方式，所述氰基数量≥2的多腈化合物包括如下物质中的至少一种：
Figure PCTCN2020133988-appb-000004
根据本申请的一些实施方式，所述磺酸脂类化合物选自环状磺酸酯类化合物，所述环状磺酸酯类化合物包含环状单磺酸酯和环状二磺酸酯中的一种或多种。
根据本申请的一些优选实施方式，所述磺酸酯类化合物包含式VI所示的化合物中的至少一种：
Figure PCTCN2020133988-appb-000005
式VI中，A和B各自独立地表示亚烷基或氟代亚烷基，且L表示单键或-OSO 2-基。
根据本申请的一些实施方式，A和B各自独立地表示C 1-C 8的亚烷基或C 1-C 8的氟代亚烷基。
根据本申请的一些优选实施方式，式VI所示化合物包括由式VI-1表示的环状单磺酸酯化合物：
Figure PCTCN2020133988-appb-000006
其中R 611和R 612各自独立地表示氢原子、氟原子或C 1-C 4烷基，且n为1、2、3或4；
根据本申请的一些进一步的优选实施方式，式VI所示的化合物包括由下式VI-2表示的环状二磺酸酯化合物。
Figure PCTCN2020133988-appb-000007
其中R 621和R 622各自独立地表示原子、氟原子或C 1-C 4烷基，且n为1、2、3或4，且如果n为2以上，则多个R 623可以彼此相同或不同，且多个R624可以彼此相同或不同。
根据本申请的一些进一步的优选实施方式，所述环状磺酸酯包括1，3-丙烷磺酸内酯、 1，2-丙烷磺酸内酯、1，4-丁烷磺酸内酯、1，2-丁烷磺酸内酯、1，3-丁烷磺酸内酯，2，4-丁烷磺酸内酯、1，3-戊烷磺酸内酯、甲烷二磺酸亚甲酯和甲烷二磺酸亚乙酯中的至少一种。
根据本申请的一些实施方式，所述含硼锂盐化合物包括式VII所示化合物：
Figure PCTCN2020133988-appb-000008
其中，M +表示碱金属阳离子。
根据本申请的一些实施方式，所述电解液进一步还包括环状碳酸酯化合物。
根据本申请的一些实施方式，所述环状碳酸酯包括氟代环状碳酸酯和/或不饱和环状碳酸酯中的至少一种。
根据本申请的一些实施方式，所述氟代环状碳酸酯包括具有2-6个碳原子的亚烷基的环状碳酸酯的氟化物。
根据本申请的一些实施方式，所述氟代环状碳酸酯包括氟代碳酸亚乙酯、4，4-二氟碳酸亚乙酯、4，5-二氟碳酸亚乙酯、4-氟-4-甲基碳酸亚乙酯、4，5-二氟-4-甲基碳酸亚乙酯、4-氟-5-甲基碳酸亚乙酯、4，4-二氟-5-甲基碳酸亚乙酯、4-(氟甲基)-碳酸亚乙酯、4-(二氟甲基)-碳酸亚乙酯、4-(三氟甲基)-碳酸亚乙酯、4-(氟甲基)-4-氟碳酸亚乙酯、4-(氟甲基)-5-氟碳酸亚乙酯、4-氟-4，5-二甲基碳酸亚乙酯、4，5-二氟-4，5-二甲基碳酸亚乙酯和4，4-二氟-5，5-二甲基碳酸亚乙酯中的至少一种。
在本申请的第二个方面，本申请还提供了一种电化学装置，其包括正极、负极和根据本申请所述的电解液。
根据一些实施方式，所述正极包含集流体以及设置于所述集流体表面的活性物质层和绝缘层。
在本申请的第三个方面，本申请进一步提供了一种电子装置，其包括本申请第二方面所述的电化学装置。
本申请提供的电解液和包含该电解液的电化学装置，能够显著改善高电压电池高温循环、高温存储性能。
附图说明
图1示出根据本申请的一个实施方式的电化学装置的正极，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)。
具体实施方式
下面结合具体实施方式，进一步阐述本申请。应理解，这些具体实施方式仅用于说明本申请而不用于限制本申请的范围。
为了简明，本文仅具体地公开了一些数值范围。然而，任意下限可以与任何上限组合形成未明确记载的范围；以及任意下限可以与其它下限组合形成未明确记载的范围，同样任意上限可以与任意其它上限组合形成未明确记载的范围。此外，每个单独公开的点或单个数值自身可以作为下限或上限与任意其它点或单个数值组合或与其它下限或上限组合形成未明确记载的范围。
在本文的描述中，除非另有说明，“以上”、“以下”为包含本数，“一种或几种”中“几种”的含义是两种及两种以上。
除非另有说明，本申请中使用的术语具有本领域技术人员通常所理解的公知含义。除非另有说明，本申请中提到的各参数的数值可以用本领域常用的各种测量方法进行测量(例如，可以按照在本申请的实施例中给出的方法进行测试)。
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％。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。
术语“烃基”涵盖烷基、烯基、炔基。
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。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。
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闭。除非另有定义，否则所述烯基通常含有2个到20个碳原子且包括(例如)-C2-4烯基、-C2-6烯基及-C2-10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。
术语“炔基”是指可为直链或具支链且具有至少一个且通常具有1个、2个或3个碳碳三键的单价不饱和烃基团。除非另有定义，否则所述炔基通常含有2个到20个碳原子且包括(例如)-C2-4炔基、-C3-6炔基及-C3-10炔基。代表性炔基包括(例如)乙炔基、丙-2-炔基(正-丙炔基)、正-丁-2-炔基、正-己-3-炔基等。
术语“亚烷基”意指可为直链或具支链的二价饱和烃基。除非另有定义，否则所述亚烷基通常含有2到10个碳原子，且包括(例如)-C2-3亚烷基和-C2-6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。
如本文中所使用，各组分的含量均为基于电解液的总重量。
一、电解液
本申请提供了一种电解液，其包括式I化合物。
本申请的发明人发现，式I化合物可以改善高温循环和高温存储性能。这是因为，式I化合物中的N上非共用电子对可以使电解液中盐的阴离子趋于稳定化，硫可以与活性氧反应，抑制电解液分解，形成富含硫的界面膜，提升界面膜的机械稳定性，改善循环性能；此外，式I化合物的氧化电位较低，可以优先在正极表面形成固体电解质相界面膜(即CEI膜)，对正极加以保护，减少正极材料与电解液接触引起的化学产气，进而改善循环和高温存储性能。同时，式I化合物可以拓宽溶剂的氧化窗口，提升溶剂的耐氧化性，改善高温性能。
1、式I化合物
Figure PCTCN2020133988-appb-000009
式I中，R 1、R 2和R 3各自独立地选自氢、卤素、取代或未取代的烷基、取代或未取代的烯基、取代或未取代的炔基和取代或未取代的含杂原子基团；其中，经取代时，取代 基选自卤素；所述杂原子包括O、S、P、N、Si和B中的至少一种；R 1、R 2和R 3中至少一个具有不饱和官能团。
根据本申请的一些实施方式，在一些实施例中，R 1具有不饱和官能团。在一些实施例中，R 2具有不饱和官能团。在一些实施例中，R 3具有不饱和官能团。
根据本申请的一些优选实施方式，所述不饱和官能团选自碳碳双键和碳碳三键。在一些实施例中，所述不饱和官能团为碳碳双键。在一些实施例中，所述不饱和官能团为碳碳三键。
根据本申请的一些实施方式，式I中，R 1、R 2和R 3各自独立地选自氢、卤素、取代或未取代的C 1-C 10烷基、取代或未取代的C 2-C 10烯基、取代或未取代的C 2-C 10炔基和取代或未取代的C 1-C 10含杂原子基团。
根据本申请的一些实施方式，式I中，所述含杂原子基团包括酯基、酮基、醛基、氨基、胺基、硼酸酯基、烷氧基、硫醇基和氰基。
根据本申请的一些进一步的实施方式，式I所示化合物包括如下化合物中的至少一种：
Figure PCTCN2020133988-appb-000010
Figure PCTCN2020133988-appb-000011
根据本申请的一些实施方式，基于电解液的质量，所述式I化合物的质量百分数为0.01％～2％。根据本申请的一些实施例，所述式I化合物在电解液中的质量百分数为0.1％～1.5％。根据本申请的一些优选实施例，所述式I化合物在电解液中的质量百分数为0.3％～1.0％。
2、添加剂
根据本申请的一些实施方式，所述电解液可进一步包含添加剂。根据一些实施方式，所述添加剂包括腈类数量≥2的多腈化合物、磺酸酯类化合物、环状碳酸酯化合物、含硼锂盐化合物中的至少一种。
(1)腈类数量≥2的多腈化合物
根据本申请，所述的电解液可以进一步包含腈类数量≥2的多腈化合物，所述腈类数量≥2的多腈化合物在电解液中的质量百分数为：0.10％-15％。
根据本申请的一些实施方式，所述氰基数量≥2的多腈化合物包含式(II)至式(V)所示的化合物中的至少一种：
N≡C-R 21-C≡N
式(II)
Figure PCTCN2020133988-appb-000012
Figure PCTCN2020133988-appb-000013
其中，R 21选自取代或未取代的C 1～C 12亚烷基、取代或未取代的C 1～C 12亚烷氧基；R 31和R 32各自独立地选自单键或取代或未取代的C 1～C 12亚烷基；R 41、R 42和R4 3各自独立地选自单键、取代或未取代的C 1～C 12亚烷基、取代或未取代的C 1～C 12亚烷氧基；R 51选自取代或未取代的C 1～C 12亚烷基、取代或未取代的C 2～C 12亚烯基、取代或未取代的C 6～C 26亚芳基、取代或未取代的C 2-C 12亚杂环基团；其中经取代时，取代基为卤素原子。
根据本申请的一些实施方式，所述氰基数量≥2的多腈化合物包括如下物质中的至少一种：
Figure PCTCN2020133988-appb-000014
Figure PCTCN2020133988-appb-000015
(2)磺酸酯类化合物
根据本申请，所述的电解液可以进一步包含磺酸酯类化合物。根据一些实施方式，所述磺酸酯类化合物在电解液中的质量百分数为：0.10％-10％。
根据本申请的一些实施方式，所述磺酸酯类化合物包含环状单磺酸酯、环状二磺酸酯中的一种或多种。
根据本申请的一些实施方式，所述磺酸酯类化合物包含式VI所示的化合物中的至少一种：
Figure PCTCN2020133988-appb-000016
其中A和B各自独立的表示亚烷基或氟代亚烷基，且L表示单键或-OSO 2-基。
根据本申请的一些实施方式，在式VI中，亚烷基的碳原子数为1～8，优选为1～6，且更优选为1～4。氟代亚烷基指的是未取代的亚烷基的至少一个氢原子被用氟原子取代。在式VI中，氟化亚烷基的碳原子数例如为1～8，优选为1～6，且更优选为1～4。所述-OSO 2-基可以为任一取向。
在式VI中，如果L为单键，则环状磺酸酯为环状单磺酸酯，环状单磺酸酯为由下式VI-1表示的化合物。
Figure PCTCN2020133988-appb-000017
其中R 611和R 612各自独立地表示氢原子、氟原子或具有1～4个碳原子的烷基，且n为1、2、3或4。
在式VI中，如果L为-OSO 2-基，则环状磺酸酯为环状二磺酸酯，且环状二磺酸酯优选为由下式VI-2表示的化合物。
Figure PCTCN2020133988-appb-000018
其中R 621和R 622各自独立地表示氢原子、氟原子或具有1～4个碳原子的烷基，且n为1、2、3或4，且如果n为2以上，则多个R 623可以彼此相同或不同，且多个R 624可以彼此相同或不同。
环状磺酸酯的实例包括单磺酸酯(当在式VI中的X为单键时)如1，3-丙烷磺酸内酯、1，2-丙烷磺酸内酯、1，4-丁烷磺酸内酯、1，2-丁烷磺酸内酯、1，3-丁烷磺酸内酯，2，4-丁烷磺酸内酯、1，3-戊烷磺酸内酯和二磺酸酯(当在式VI中的X为-OSO 2-基时)如甲烷二磺酸亚甲酯和甲烷二磺酸亚乙酯。其中，考虑到形成膜的效果、可获得的容易性和成本，优选为1，3-丙烷磺酸内酯(PS)、1，4-丁烷磺酸内酯(BS)和甲烷二磺酸亚甲酯(MMDS)。特别地，环状二磺酸酯具有容易地在负极上形成具有优异质量的膜的特性。
在电解液中进一步添加环状磺酸酯化合物可以改善锂离进一步改善锂离子电池的高温循环、高温存储性能，且能进一步改善浮充性能；这是因为环状硫酸酯化合物在正负极均能形成机械稳定性优异的界面膜，该界面膜可显著抑制正负极界面副反应，进一步提升界面膜的热稳定性和机械稳定性，改善循环性能和高温存储性能；特别地，环状二磺酸酯具有容易地在负极上形成具有优异质量的膜的特性，与环状单磺酸酯结合使用，可以起到更优异的改善。
(3)环状碳酸酯化合物
根据本申请，所述的电解液可以进一步包含环状碳酸酯化合物，在电解液中的质量 百分数为0.01％至10％。
根据本申请的一些实施方式，所述环状碳酸酯化合物包括氟代环状碳酸酯和/或不饱和环状碳酸酯中的至少一种。根据一些实施方式，所述氟代环状碳酸酯选自具有2-6个碳原子的亚烷基的环状碳酸酯的氟化物。所述氟代环状碳酸酯的示例包括，但不限于，氟代碳酸亚乙酯、4，4-二氟碳酸亚乙酯、4，5-二氟碳酸亚乙酯、4-氟-4-甲基碳酸亚乙酯、4，5-二氟-4-甲基碳酸亚乙酯、4-氟-5-甲基碳酸亚乙酯、4，4-二氟-5-甲基碳酸亚乙酯、4-(氟甲基)-碳酸亚乙酯、4-(二氟甲基)-碳酸亚乙酯、4-(三氟甲基)-碳酸亚乙酯、4-(氟甲基)-4-氟碳酸亚乙酯、4-(氟甲基)-5-氟碳酸亚乙酯、4-氟-4，5-二甲基碳酸亚乙酯、4，5-二氟-4，5-二甲基碳酸亚乙酯和4，4-二氟-5，5-二甲基碳酸亚乙酯。
(4)含硼锂盐化合物
根据本申请，所述的电解液可以进一步包括含硼锂盐化合物，优选包含四硼酸金属盐化合物。在一些实施例中，基于所述电解液的总重量，含硼锂盐化合物的含量为0.01wt％至1wt％。
在本申请的一些实施方式中，含硼锂盐化合物为四硼酸金属盐化合物，具体可以选自式VII所示化合物：
Figure PCTCN2020133988-appb-000019
其中M +表示碱金属阳离子。碱金属阳离子的示例包括但不限于，锂离子、钠离子、钾离子、铯离子。
在本申请的一些实施方式中，所述式VII化合物选自以下化合物的一种或多种：
Figure PCTCN2020133988-appb-000020
Figure PCTCN2020133988-appb-000021
(5)此外，所述电解液中还可以进一步包括氟代吡啶，如：二氟吡啶、五氟吡啶等。
3、锂盐
本申请的电解液中所使用的电解质锂盐选自无机锂盐和有机锂盐中的一种或几种。
根据本申请的一些实施方式，所述锂盐选自六氟磷酸锂(LiPF 6)、四氟硼酸锂(LiBF4)、双氟磺酰亚胺锂(LiFSI)、双三氟甲烷磺酰亚胺锂(LiTFSI)、二氟磷酸锂(LiPO 2F 2)中的一种或几种，进一步优选地，所述锂盐选自六氟磷酸锂(LiPF 6)。
4、溶剂
本申请的电解液中使用的溶剂可为现有技术中已知的任何可作为电解液的溶剂的非水溶剂。
在本申请的一些实施例中，非水溶剂包括，但不限于，环状碳酸酯、链状碳酸酯、环状羧酸酯、链状羧酸酯、环状醚、链状醚、含磷有机溶剂、含硫有机溶剂和芳香族含氟溶剂。
在本申请的一些实施例中，环状碳酸酯包括，但不限于，碳酸亚乙酯(ethylene carbonate，EC)、碳酸亚丙酯(propylene carbonate，PC)和碳酸亚丁酯。在一些实施例中，环状碳酸酯具有3-6个碳原子。
在本申请的一些实施例中，链状碳酸酯包括，但不限于，碳酸二甲酯、碳酸甲乙酯、碳酸二乙酯(diethyl carbonate，DEC)、碳酸甲基正丙基酯、碳酸乙基正丙基酯、碳酸二正丙酯等链状碳酸酯，作为被氟取代的链状碳酸酯，例如双(氟甲基)碳酸酯、双(二氟甲基)碳酸酯、双(三氟甲基)碳酸酯、双(2-氟乙基)碳酸酯、双(2，2-二氟乙基)碳酸酯、双(2，2，2-三氟乙基)碳酸酯、2-氟乙基甲基碳酸酯、2，2-二氟乙基甲基碳酸酯和2，2，2-三氟乙基甲基碳酸酯。
在本申请的一些实施例中，环状羧酸酯包括，但不限于，γ-丁内酯和γ-戊内酯。在一些实施例中，环状羧酸酯的部分氢原子可被氟取代。
在本申请的一些实施例中，链状羧酸酯包括，但不限于，乙酸甲酯、乙酸乙酯、乙酸丙酯、乙酸异丙酯、乙酸丁酯、乙酸仲丁酯、乙酸异丁酯、乙酸叔丁酯、丙酸甲酯、丙酸乙酯、丙酸丙酯、丙酸异丙酯、丁酸甲酯、丁酸乙酯、丁酸丙酯、异丁酸甲酯、异丁酸乙酯、戊酸甲酯、戊酸乙酯、特戊酸甲酯和特戊酸乙酯。在一些实施例中，链状羧酸酯的部分氢原子可被氟取代。在一些实施例中，氟取代的链状羧酸酯包括，但不限于，三氟乙酸甲酯、三氟乙酸乙酯、三氟乙酸丙酯、三氟乙酸丁酯和三氟乙酸2，2，2-三氟乙酯。
在本申请的一些实施例中，环状醚包括，但不限于，四氢呋喃、2-甲基四氢呋喃、1，3-二氧戊环、2-甲基1，3-二氧戊环、4-甲基1，3-二氧戊环、1，3-二氧六环、1，4-二氧六环和二甲氧基丙烷。
在本申请的一些实施例中，链状醚包括，但不限于，二甲氧基甲烷、1，1-二甲氧基乙烷、1，2-二甲氧基乙烷、二乙氧基甲烷、1，1-二乙氧基乙烷、1，2-二乙氧基乙烷、乙氧基甲氧基甲烷、1，1-乙氧基甲氧基乙烷和1，2-乙氧基甲氧基乙烷。
在本申请的一些实施例中，含磷有机溶剂包括，但不限于，磷酸三甲酯、磷酸三乙酯、磷酸二甲基乙酯、磷酸甲基二乙酯、磷酸亚乙基甲酯、磷酸亚乙基乙酯、磷酸三苯酯、亚磷酸三甲酯、亚磷酸三乙酯、亚磷酸三苯酯、磷酸三(2，2，2-三氟乙基)酯和磷酸三(2，2，3，3，3-五氟丙基)酯。
在本申请的一些实施例中，含硫有机溶剂包括，但不限于，环丁砜、2-甲基环丁砜、3-甲基环丁砜、二甲基砜、二乙基砜、乙基甲基砜、甲基丙基砜、二甲基亚砜、甲磺酸甲酯、甲磺酸乙酯、乙磺酸甲酯、乙磺酸乙酯、硫酸二甲酯、硫酸二乙酯和硫酸二丁酯。在一些实施例中，含硫有机溶剂的部分氢原子可被氟取代。
在本申请的一些实施例中，芳香族含氟溶剂包括，但不限于，氟苯、二氟苯、三氟苯、四氟苯、五氟苯、六氟苯和三氟甲基苯。
在本申请的一些实施例中，本申请的电解液中使用的溶剂包括如上所述的一种或多种。在一些实施例中，本申请的电解液中使用的溶剂选自环状碳酸酯、链状碳酸酯、环状羧酸酯、链状羧酸酯及其组合。在一些实施例中，本申请的电解液中使用的溶剂包含选自由下列物质组成的群组的有机溶剂：碳酸亚乙酯、碳酸亚丙酯、碳酸二乙酯、丙酸乙酯、丙酸丙酯、乙酸正丙酯、乙酸乙酯及其组合。
在一些实施例中，本申请的电解液中使用的溶剂选自：碳酸乙烯酯、碳酸丙烯酯、 碳酸二乙酯、丙酸乙酯、丙酸丙酯、γ-丁内酯及其组合。
在一些优选实施例中，本申请的电解液中使用的溶剂为碳酸乙烯酯、碳酸丙烯酯、碳酸二乙酯的组合。
二、电化学装置
本申请的电化学装置是指能够发生电化学反应的任何装置它的具体实例包括所有种类的一次电池、二次电池、燃料电池、太阳能电池或电容。特别地，该电化学装置是锂二次电池，包括锂金属二次电池、锂离子二次电池、锂聚合物二次电池或锂离子聚合物二次电池。在一些实施例中，本申请的电化学装置包括具有能够吸留、放出金属离子的正极活性物质的正极；具有能够吸留、放出金属离子的负极活性物质的负极；和本申请的电解液。
1、电解液
本申请的锂离子电池中使用的电解液为本申请的上述任何电解液。此外，本申请的锂离子电池中使用的电解液还可包含不脱离本申请的主旨的范围内的其它电解液。
2、电极
(1)负极
根据本申请的实施例的电化学装置的负极包括集流体和形成在集流体上的负极活性物质层，负极活性物质层包括负极活性物质，负极活性物质可以包括可逆地嵌入/脱嵌锂离子的材料、锂金属、锂金属合金、能够掺杂/脱掺杂锂的材料或过渡金属氧化物，例如Si、SiOx等材料。可逆地嵌入/脱嵌锂离子的材料可以是碳材料。碳材料可以是在锂离子可再充电电化学装置中通常使用的任何碳基负极活性物质。碳材料的示例包括结晶碳、非晶碳和它们的组合。结晶碳可以是无定形的或板形的、小片形的、球形的或纤维形的天然石墨或人造石墨。非晶碳可以是软碳、硬碳、中间相沥青碳化产物、烧制焦炭等。低结晶碳和高结晶碳均可以用作碳材料。作为低结晶碳材料，可通常包括软碳和硬碳。作为高结晶碳材料，可通常包括天然石墨、结晶石墨、热解碳、中间相沥青基碳纤维、中间相碳微珠、中间相沥青和高温锻烧炭(如石油或衍生自煤焦油沥青的焦炭)。
负极活性物质层包含有粘合剂，且该粘合剂可以包括各种粘合剂聚合物，如二氟乙烯一六氟丙烯共聚物(PVDF-co-HFP)，聚偏二氟乙烯、聚丙烯睛、聚甲基丙烯酸甲醋、聚乙烯醇、羧甲基纤维素、羟丙基纤维素、聚氯乙烯、羧化的聚氯乙烯、聚氟乙烯、含亚乙基氧的聚合物、聚乙烯吡咯烷酮、聚氨酯、聚四氟乙烯、聚乙烯、聚丙烯、丁苯橡胶、丙烯酸(酯)化的丁苯橡胶、环氧树脂、尼龙等，但不限于此等。
负极活性物质层还包括导电材料来改善电极导电率。可以使用任何导电的材料作为该导电材料，只要它不引起化学变化即可。导电材料的示例包括：碳基材料，例如天然石墨、人造石墨、炭黑、乙炔黑、科琴黑、碳纤维等；金属基材料，例如包括铜、镍、铝、银等的金属粉或金属纤维；导电聚合物，例如聚亚苯基衍生物等；或它们的混合物。集流体可以为铜箔、镍箔、不锈钢箔、钛箔、泡沫镍、泡沫铜、包覆有导电金属的聚合物基板或它们的组合。
(2)正极
根据一些实施方式，本申请的电化学装置中正极包含集流体以及设置于所述集流体表面的活性物质层和绝缘层。
根据一些实施方式，所述正极包含：正极集流体，流体可以为Al，但不限于此；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。
根据一些实施方式，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，所述空隙的宽度为0mm至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。
本申请的电化学装置中使用的正极的材料构成和其制造方法可包括任何现有技术中公开的技术。
在一些实施例中，正极活性物质包括，但不限于，硫化物、磷酸盐化合物和锂过渡金属复合氧化物。在一些实施例中，正极活性物质包括锂过渡金属系化合物，其具有能够脱离、插入锂离子的结构。
在一些实施例中，正极包括任何现有技术中公开的构成。在一些实施例中，正极通过在集流体上用包括锂过渡金属系化合物粉体和粘结剂的正极活性物质层形成正极材料而制成。
在一些实施例中，正极活性物质层通常通过以下操作来制作：将正极材料和粘结剂(根据需要可进一步使用导电材料和增稠剂等)进行干式混合而制成片状，将得到的片压接于正极集流体，或者使这些材料溶解或分散于液体介质中而制成浆料状，将该浆料涂布在正 极集流体上并进行干燥。在一些实施例中，正极活性物质层包括任何现有技术中公开的材料。
3、隔膜
在一些实施例中，本申请的电化学装置在正极与负极之间设有隔膜以防止短路。本申请的电化学装置中使用的隔膜的材料和形状没有特别限制，其可为任何现有技术中公开的技术。在一些实施例中，隔膜包括由对本申请的电解液稳定的材料形成的聚合物或无机物等。
例如隔膜可包括基材层和表面处理层。基材层为具有多孔结构的无纺布、膜或复合膜，基材层的材料选自聚乙烯、聚丙烯、聚对苯二甲酸乙二醇酯和聚酰亚胺中的至少一种。具体的，可选用聚丙烯多孔膜、聚乙烯多孔膜、聚丙烯无纺布、聚乙烯无纺布或聚丙烯-聚乙烯-聚丙烯多孔复合膜。
基材层的至少一个表面上设置有表面处理层，表面处理层可以是聚合物层或无机物层，也可以是混合聚合物与无机物所形成的层。
无机物层包括无机颗粒和粘结剂，无机颗粒选自氧化铝、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、氧化锆、氧化钇、碳化硅、勃姆石、氢氧化铝、氢氧化镁、氢氧化钙和硫酸钡中的一种或几种的组合。粘结剂选自聚偏氟乙烯、偏氟乙烯-六氟丙烯的共聚物、聚酰胺、聚丙烯腈、聚丙烯酸酯、聚丙烯酸、聚丙烯酸盐、聚乙烯呲咯烷酮、聚乙烯烷氧、聚甲基丙烯酸甲酯、聚四氟乙烯和聚六氟丙烯中的一种或几种的组合。
聚合物层中包含聚合物，聚合物的材料选自聚酰胺、聚丙烯腈、丙烯酸酯聚合物、聚丙烯酸、聚丙烯酸盐、聚乙烯呲咯烷酮、聚乙烯烷氧、聚偏氟乙烯、聚(偏氟乙烯-六氟丙烯)中的至少一种。
三、电子装置
根据本申请的电解液能够抑制电化学装置的直流内阻的增加，使得由此制造的电化学装置适用于各种领域的电子设备或装置。
本申请的电子设备或装置没有特别限定。在一些实施例中，本申请的电子设备包括但不限于，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。
以下通过具体实施例对本申请的技术方案做示例性描述：
1、电池制备
1)电解液的制备：在含水量＜10ppm的氩气气氛手套箱中，将碳酸乙烯酯(简写为EC)、碳酸丙烯酯(简写为PC)、碳酸二乙酯(简写为DEC)，按照3∶3∶4的质量比混合均匀，再将充分干燥的锂盐LiPF 6(1M)溶解于上述非水溶剂，最后加入一定质量的添加剂，配成实施例中的电解液。
其中，对比例3中的添加剂为
Figure PCTCN2020133988-appb-000022
2)正极极片的制备：将正极活性物质LCO(分子式为LiCoO 2)、导电碳黑、粘结剂聚偏二氟乙烯(简写为PVDF)按重量比97.1∶1.3∶1.6在适量的N-甲基吡咯烷酮(简写为NMP)溶剂中充分搅拌混合，使其形成均匀的正极浆料；将此浆料涂覆于正极集流体Al箔上，烘干、冷压，得到正极极片，正极压实密度为4.15g/cm 3。
3)负极极片的制备：将负极活性物质石墨、粘结剂丁苯橡胶(简写为SBR)、增稠剂羧甲基纤维素钠(简写为CMC)按照重量比97.7∶1.3∶1.0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Cu箔上，烘干、冷压，得到负极极片，负极压实密度为1.75g/cm 3。
4)隔离膜的制备
选用7μm厚的聚乙烯(PE)隔离膜。
5)锂离子电池的制备：将正极极片、隔膜、负极极片按顺序叠好，使隔膜处于正极极片和负极极片之间起到隔离的作用，然后卷绕得到裸电池；将裸电池置于外包装箔中，将上述制备好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)85℃存储电池膨胀率
将电池在25℃下以0.5C充电至4.5V，4.5V下恒压充电至0.05C，用千分尺测试并记录电池的厚度记为H11，放置到85℃烘箱当中，12小时结束后用千分尺测试并记录电池的厚度，记为H12。
厚度膨胀率＝(H12-H11)/H11×100％
2)锂离子电池高温循环测试
将锂离子电池置于45℃恒温箱中，静置30分钟，使锂离子电池达到恒温。将达到恒温的锂离子电池在45℃下以0.2C恒流充电至4.5V，4.5V下恒压充电至0.05C，静置5分钟，再以0.2C恒流放电至3.0V，静置5min；然后再以1.3C恒流充电至4.15V，然后以4.15V恒压充电至电流为1C；再以1C恒流充电至4.25V，然后以4.25V恒压充电至电流为0.8C；再以0.8C恒流充电至4.5V，然后以4.5V恒压充电至电流为0.05C；放置5分钟；接着以1C恒流放电至电压为3.0V，静置3分钟；此为一个充放电循环。如此充电/放电，计算电池循环N次后的容量保持率。
锂离子电池N次循环后的容量保持率(％)＝第N次循环的放电容量/第1次循环放电容量×100％。
3)锂离子电池直流阻抗DCR(0℃)测试
将锂离子电池在0℃高低温箱中静置1小时，使锂离子电池达到恒温；以0.5C恒流充电至4.2V，再以0.3C恒流充电至4.5V，4.5V恒压充电至电流为0.02C，静置30分钟；再以0.1C恒流放电至3.4V，静置30分钟，此步容量作为基准。0℃条件下以0.5C恒流充电至4.2V，再以0.3C恒流充电至4.5V，4.5V恒压充电至电流为0.02C，静置30分钟；以0.1C恒流放电60min(用上一步得到的实际容量计算)，记录此时的电压为V 1；再以1C恒流放电1s(容量以电池标注容量计算)，记录此时的电压为V 2，计算电池20％SOC状态对应直流阻抗。
20％SOC直流阻抗＝(V 1-V 2)/1C。
4)热箱测试
在25℃下，将锂离子电池以0.7C恒流充电至4.5V，4.5V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，记录电池的电压、温度以及热箱温度的变化。电池不起火、不爆炸、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。
5)锂离子电池45℃浮充测试
将电池在25℃以1.3C恒流充电至4.15V，然后以4.15V恒压充电志电流为1C；以 1C恒流充电至4.25V，然后以4.25V恒压充电至电流为0.8；再以0.8C恒流充电至4.5V，然后以4.5V恒压充电至电流为0.05C；用千分尺测试并记录电池的厚度记为D 11；45℃静置1小时，以0.4C恒流充电至4.55V，然后以4.55V恒压充电1000h，用千分尺测试并记录电池的厚度记为D 12；
厚度膨胀率＝(D 12-D 11)/D 11×100％。
3、测试结果
Figure PCTCN2020133988-appb-000023
通过对比实施例1-5和对比例1、2可知，式I化合物可以改善高温循环和高温存储性能，这是由于化合物I中的N的非共用电子对可以使电解液中盐的阴离子趋于稳定化，且特别的式I化合物中包括的具有不饱和官能团可在负极表面上被还原形成稳定的离子导电膜；同时，式I化合物的氧化电位较低，可以优先在正极表面形成固体电解质相界面膜(即CEI膜)，对正极加以保护，减少正极材料与电解液接触引起的化学产气，进而改善循环和高温存储性能；通过对比实施例3和对比例3可知不饱和键的引入可以进一步改善循环性能以及高温存储厚度膨胀率，这是因为不饱和官能团的引入，可以优先在阳极还原形稳定的SEI膜，抑制电解液与电极界面的副反应，从而改善循环性能和高温存储性能。
通过对比实施例1-7和对比例1、2可知，通过式I化合物与多腈化合物结合使用，可以进一步改善高温循环和高温存储性能，且能进一步改善热箱性能，这这主要归因于多腈的存在使得正极界面的热稳定性更高，有利于改善高温高压下正极结构的稳定性，正极结构稳定性的改善进一步减少电解液在正极界面的氧化分解，从而减少反应热的产生。此外，在保证电池安全性能的基础上，通过引入多腈与式I化合物组合使用，减少了式I化合物的用量；两者相互结合，提升界面膜的热稳定性和机械稳定性，改善循环性能和高温存储性能和安全性能。
通过对比实施例5-10可以看出，三腈以上腈的含量过高会导致对铜箔的腐蚀，而将其与二腈进行组合并且调节二者的比例可以避免该现象的发生。
通过对比实施例1-7和实施例11-14可以看出，不同的式I化合物可以起到类似的作用。
(2)表2展示了环状磺酸酯添加剂对电池性能的影响。
Figure PCTCN2020133988-appb-000024
Figure PCTCN2020133988-appb-000025
通过对比实施例23-27和对比例6-7可以看出，含四硼酸盐化合物的电解液的DCR和高温存储性能得到明显改善，这是因为四硼酸盐化合物在负极可形成致密稳定的界面膜，形成的界面膜具有较高的离子传导率和较强的电子绝缘，显著改善界面阻抗，降低DCR；其与上述结构添加剂协同作用，形成有机-无机界面膜，降低了界面膜的阻抗同时改善了界面膜机械强度，表现出较高的热稳定性和化学稳定性。
通过对比实施例23-27可知，含四硼酸盐化合物含量为0.3％时电性能最优，含量为0.1％时电性能较优，含量为0.5％或0.7％时电性能一般，但是当含量超过1％时电性能发生恶化；这是因为当含四硼酸盐化合物添加剂含量过低时，难以充分在极片表面形成密薄均匀的保护膜，从而无法有效抑制金属离子催化电解液的氧化分解反应；当含四硼酸盐化合物添加剂含量过高时，在形成的保护膜过厚，导致阻抗增加，降低电性能。
(4)表4展示了正极绝缘涂层对电池性能的影响。
表4实施例28～31的电解液
Figure PCTCN2020133988-appb-000026
如实施例30和31中的绝缘涂层位于相邻两个第一表面正极活性物质层之间，绝缘层两端与第一表面活性物质层之间有1mm的空隙，绝缘层成份为氧化铝，厚度为10um。
通过表4的数据可以发现，绝缘涂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，推测绝缘涂层的存在，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。

Claims (16)

  1. 一种电解液，包括式I化合物，
    Figure PCTCN2020133988-appb-100001
    式I中，R 1、R 2和R 3各自独立地选自氢、卤素、取代或未取代的烷基、取代或未取代的烯基、取代或未取代的炔基和取代或未取代的含杂原子基团；
    其中，经取代时，取代基选自卤素；
    所述杂原子包括O、S、P、N、Si和B中的至少一种；
    R 1、R 2和R 3中至少一个具有不饱和官能团。
  2. 根据权利要求1所述的电解液，其中，所述不饱和官能团包括碳碳双键、碳碳三键中的至少一种。
  3. 根据权利要求1所述的电解液，其中，式I中，R 1、R 2和R 3各自独立地选自氢、卤素、取代或未取代的C 1-C 10烷基、取代或未取代的C 2-C 10烯基、取代或未取代的C 2-C 10炔基和取代或未取代的C 1-C 10含杂原子基团。
  4. 根据权利要求1所述的电解液，其中，所述含杂原子基团选自酯基、酮基、醛基、氨基、胺基、硼酸酯基、烷氧基、硫醇基和氰基。
  5. 根据权利要求1所述的电解液，其中，式I化合物选自如下化合物中的一种或多种：
    Figure PCTCN2020133988-appb-100002
    Figure PCTCN2020133988-appb-100003
  6. 根据权利要求1所述的电解液，其中，基于所述电解液的质量，所述式I化合物的质量百分含量为0.01％～2％。
  7. 根据权利要求1所述的电解液，还包括氰基数量≥2的多腈化合物、磺酸酯类化合物和含硼锂盐化合物中的至少一种。
  8. 根据权利要求7所述的电解液，其中，基于所述电解液的质量，所述氰基数量≥2的多腈化合物的质量百分含量为0.10％-15％，所述磺酸酯类化合物的质量百分含量为0.10％-10％，所述含硼锂盐化合物的质量百分含量为0.01％至5％。
  9. 根据权利要求7所述的电解液，其中，所述氰基数量≥2的多腈化合物包含式(II)至式(V)所示的化合物中的至少一种：
    N≡C-R 21-C≡N
    式(II)
    Figure PCTCN2020133988-appb-100004
    Figure PCTCN2020133988-appb-100005
    其中，R 21选自取代或未取代的C 1～C 12亚烷基、取代或未取代的C 1～C 12亚烷氧基；R 31和R 32各自独立地选自单键或取代或未取代的C 1～C 12亚烷基；R 41、R 42和R 43各自独立地选自单键、取代或未取代的C 1～C 12亚烷基、取代或未取代的C 1～C 12亚烷氧基；R 51选自取代或未取代的C 1～C 12亚烷基、取代或未取代的C 2～C 12亚烯基、取代或未取代的C 6～C 26亚芳基、取代或未取代的C 2-C 12亚杂环基团；其中经取代时，取代基为卤素原子。
  10. 根据权利要求9所述的电解液，其中，所述氰基数量≥2的多腈化合物包括如下物质中的至少一种：
    Figure PCTCN2020133988-appb-100006
    Figure PCTCN2020133988-appb-100007
  11. 根据权利要求7所述的电解液，其中，所述磺酸酯类化合物包含式VI所示的化合物中的至少一种：
    Figure PCTCN2020133988-appb-100008
    式VI中，A和B各自独立地表示C 1-C 8亚烷基或氟代C 1-C 8亚烷基，且L表示单键或-OSO 2-基。
  12. 根据权利要求11所述的电解液，其中，所述磺酸酯类化合物包括1，3-丙烷磺酸内酯、1，2-丙烷磺酸内酯、1，4-丁烷磺酸内酯、1，2-丁烷磺酸内酯、1，3-丁烷磺酸内酯，2，4-丁烷磺酸内酯、1，3-戊烷磺酸内酯、甲烷二磺酸亚甲酯和甲烷二磺酸亚乙酯中的至少一种。
  13. 根据权利要求7所述的电解液，其中，所述含硼锂盐化合物包含式VII所示化合物中的至少一种：
    Figure PCTCN2020133988-appb-100009
    其中，M +表示碱金属阳离子。
  14. 一种电化学装置，包括正极、负极和权利要求1-13任一项所述的电解液。
  15. 根据权利要求14所述的电化学装置，所述正极包含集流体以及设置于所述集流体表面的活性物质层和绝缘层。
  16. 一种电子装置，包括权利要求14或15所述的电化学装置。
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