WO2021128206A1 - 一种电解液及电化学装置 - Google Patents

一种电解液及电化学装置 Download PDF

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WO2021128206A1
WO2021128206A1 PCT/CN2019/128852 CN2019128852W WO2021128206A1 WO 2021128206 A1 WO2021128206 A1 WO 2021128206A1 CN 2019128852 W CN2019128852 W CN 2019128852W WO 2021128206 A1 WO2021128206 A1 WO 2021128206A1
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electrochemical device
active material
electrolyte
fluorinated
negative electrode
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PCT/CN2019/128852
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English (en)
French (fr)
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唐超
刘俊飞
张丽兰
郑建明
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宁德新能源科技有限公司
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Priority to PCT/CN2019/128852 priority Critical patent/WO2021128206A1/zh
Priority to US16/962,777 priority patent/US20210408595A1/en
Priority to CN201980024334.3A priority patent/CN112005418A/zh
Publication of WO2021128206A1 publication Critical patent/WO2021128206A1/zh

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    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07D—HETEROCYCLIC COMPOUNDS
    • C07D327/00—Heterocyclic compounds containing rings having oxygen and sulfur atoms as the only ring hetero atoms
    • 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
    • H01M10/05—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
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/133—Electrodes based on carbonaceous material, e.g. graphite-intercalation compounds or CFx
    • 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
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/134—Electrodes based on metals, Si or alloys
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
    • H01M4/583—Carbonaceous material, e.g. graphite-intercalation compounds or CFx
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
    • H01M4/583—Carbonaceous material, e.g. graphite-intercalation compounds or CFx
    • H01M4/587—Carbonaceous material, e.g. graphite-intercalation compounds or CFx for inserting or intercalating light metals
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • 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
    • H01M4/624—Electric conductive fillers
    • H01M4/625—Carbon or graphite
    • 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
    • H01M2004/021—Physical characteristics, e.g. porosity, surface area
    • 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
    • H01M2004/027—Negative electrodes
    • 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
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/362—Composites
    • H01M4/366—Composites as layered products
    • 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

  • This application relates to the field of energy storage technology, and in particular to an electrolyte and an electrochemical device containing the electrolyte.
  • Lithium-ion batteries have the advantages of high energy density, high working voltage, low self-discharge rate, long cycle life, and no pollution. They have been widely used in computers, smart wearable devices, smart phones, drones, and electric vehicles. With the development of modern information technology and the expansion of the application range of lithium-ion batteries, the endurance of lithium-ion batteries in this field has higher requirements.
  • the present invention provides an electrolyte and an electrochemical device containing the electrolyte.
  • the electrolyte can generate a stable protective layer on the surface of the silicon negative electrode.
  • the protective layer is not easy to generate gas under over-discharge conditions, and can stably adhere to the silicon negative electrode, thereby inhibiting the side reaction of the electrolyte on the silicon negative electrode and improving The cycle life of lithium-ion battery with silicon negative electrode and the problem of gas generation under over-discharge are solved.
  • the present invention provides an electrochemical device, including a positive electrode, a negative electrode and an electrolyte; wherein
  • the anode includes an anode active material layer, the anode active material layer includes an anode active material, and the anode active material includes a silicon-containing compound;
  • the electrolyte contains at least one sulfonic anhydride compound having formula I, formula II or formula III:
  • R 1 to R 18 are each independently selected from hydrogen, halogen, substituted or unsubstituted C 1 -C 7 alkyl, substituted or unsubstituted C 2 -C 7 alkenyl, substituted or unsubstituted C 2 -C 7 alkynyl, substituted or unsubstituted C 6 -C 10 aryl, substituted or unsubstituted C 1 -C 7 alkoxy or substituted or unsubstituted C 6 -C 10 aryloxy ;
  • the substituent when substituted, is halogen or cyano.
  • the sulfonic anhydride compound includes at least one of the following compounds:
  • the mass fraction of the sulfonic anhydride compound in the electrolyte is about 0.1% to about 2% by weight.
  • the mass fraction of the silicon-containing compound is about 1% to about 90% by weight.
  • the carbon nanotubes have a tube diameter of about 1 nanometer to about 10 nanometers, and a tube length of about 1 micrometer to about 50 micrometers.
  • the mass ratio of the silicon-containing compound to the carbon nanotubes is about 50 to about 300.
  • the surface of the silicon-containing compound contains an oxide Me y O z , 1 ⁇ y ⁇ 2, 1 ⁇ Z ⁇ 3, and Me is selected from at least one of Ti, Al, Zr, or Zn.
  • the loading amount of the negative electrode active material layer on the negative electrode is about 10 mg/cm 2 to about 30 mg/cm 2 .
  • the electrolyte solution further includes a fluorinated additive
  • the fluorinated additive includes a fluorinated ether having 2 to 7 carbon atoms, a fluorocarboxylic acid ester having 2 to 6 carbon atoms, or a fluorinated carboxylic acid ester having 2 to 6 carbon atoms. At least one of fluorocarbonic acid esters to 6.
  • the fluorinated additive is selected from at least one of the following compounds: ethyl methyl fluorocarbonate, dimethyl fluorocarbonate, diethyl fluorocarbonate, ethyl fluoropropionate , Propyl fluoropropionate, methyl fluoropropionate, ethyl fluoroacetate, methyl fluoroacetate or propyl fluoroacetate.
  • the mass fraction of the fluorinated additive in the electrolyte is not less than about 2% by weight.
  • the mass fraction of the fluorinated additive in the electrolyte is about 2% to about 50% by weight.
  • the fluorinated additive is selected from at least one of the following compounds:
  • the additive A includes at least one of vinylene carbonate, 1,3-propane sultone, vinyl sulfate, succinonitrile, or adiponitrilekind.
  • the mass fraction of the additive A in the electrolyte is about 0.1% to about 10% by weight, about 0.5% to about 8% by weight, about 1% to about 6% by weight, Or about 2% to about 4% by weight.
  • the mass ratio P of the fluorinated additive to the sulfonic anhydride compound satisfies: about 1 ⁇ P ⁇ about 50.
  • the mass ratio of the graphite to the silicon-containing compound is about 95:5 to about 30:70.
  • the present application provides an electronic device, which includes the electrochemical device as described above.
  • FIG. 1 is the result of infrared analysis of the negative electrode materials of the lithium ion battery of Comparative Example 1 and Example 1.
  • FIG. 1 is the result of infrared analysis of the negative electrode materials of the lithium ion battery of Comparative Example 1 and Example 1.
  • the term "about” is used to describe and illustrate small variations.
  • the term can refer to an example in which the event or situation occurs precisely and an example in which the event or situation occurs very closely.
  • the term can refer to a range of variation less than or equal to ⁇ 10% of the stated 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%, or less than or equal to ⁇ 0.01%.
  • a list of items connected by the term "one of” may mean any one of the listed items. For example, if items A and B are listed, then the phrase “one of A and B” means only A or only B. In another example, if items A, B, and C are listed, then the phrase "one of A, B, and C" means only A; only B; or only C.
  • Project A can contain a single element or multiple elements.
  • Project B can contain a single element or multiple elements.
  • Project C can contain a single element or multiple elements.
  • a list of items connected by the term "at least one of” can mean any combination of the listed items. For example, if items A and B are listed, then the phrase “at least one of A and B" or “at least one of A or B” means only A; only B; or A and B. In another example, if items A, B, and C are listed, then the phrase “at least one of A, B, and C” or “at least one of A, B, or C” means only A; or only B; C only; A and B (exclude C); A and C (exclude B); B and C (exclude A); or all of A, B, and C.
  • Project A can contain a single element or multiple elements.
  • Project B can contain a single element or multiple elements.
  • Project C can contain a single element or multiple elements.
  • the number after the capital letter “C”, such as “C 1 -C 10 ", “C 3 -C 10 “, etc., after the "C” indicates the number of carbons in a specific functional group. That is, the functional groups may include 1-10 carbon atoms and 3-10 carbon atoms, respectively.
  • C 1 -C 4 alkyl refers to an alkyl group having 1 to 4 carbon atoms, such as CH 3 -, CH 3 CH 2 -, CH 3 CH 2 CH 2 -, (CH 3 ) 2 CH- , CH 3 CH 2 CH 2 CH 2 -, CH 3 CH 2 CH(CH 3 )- or (CH 3 ) 3 C-.
  • alkyl is expected to be a linear saturated hydrocarbon structure having 1 to 7 carbon atoms. "Alkyl” is also expected to be a branched or cyclic hydrocarbon structure having 3 to 7 carbon atoms.
  • the alkyl group may be an alkyl group of 1 to 5 carbon atoms, or an alkyl group of 1 to 4 carbon atoms.
  • butyl means 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 and so on.
  • the alkyl group may be optionally substituted.
  • alkenyl refers to a monovalent unsaturated hydrocarbon group that may be straight or branched and has at least one and usually 1, 2, or 3 carbon-carbon double bonds. Unless otherwise defined, the alkenyl group usually contains 2-7 carbon atoms, for example, it may be an alkenyl group with 2 to 5 carbon atoms, or an alkenyl group with 2 to 4 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. In addition, alkenyl groups may be optionally substituted.
  • alkynyl refers to a monovalent unsaturated hydrocarbon group that can be straight or branched and has at least one and usually 1, 2, or 3 carbon-carbon triple bonds. Unless otherwise defined, the alkynyl group usually contains an alkynyl group of 2 to 7, 2 to 5, or 2 to 4 carbon atoms. Representative alkynyl groups include, for example, ethynyl, prop-2-ynyl (n-propynyl), n-but-2-ynyl, n-hex-3-ynyl, and the like. In addition, alkynyl groups may be optionally substituted.
  • aryl encompasses both monocyclic and polycyclic ring systems.
  • a polycyclic ring may have two or more rings in which two carbons are shared by two adjacent rings (the rings are "fused"), wherein at least one of the rings is aromatic, such as others
  • the ring can be a cycloalkyl, cycloalkenyl, aryl, heterocyclic, and/or heteroaryl group.
  • the aryl group may contain 6 to 10 carbon atoms.
  • Representative aryl groups include, for example, phenyl, methylphenyl, propylphenyl, isopropylphenyl, benzyl and naphth-1-yl, naphth-2-yl, and the like.
  • aryl groups may be optionally substituted.
  • aryloxy means an aryl group having the stated number of carbon atoms connected by an oxygen bridge. Where the aryl group has the meaning as described in the present invention, such examples include but are not limited to phenoxy, p-tolyloxy, p-ethylphenoxy and the like.
  • alkoxy refers to a group formed by connecting an alkyl group to an oxygen atom. Wherein the alkyl group has the meaning as described in the present invention. Representative alkoxy examples include, but are not limited to, methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, sec-butoxy, tert-butoxy, pentoxy, iso Pentyloxy or tert-pentyloxy, heptyloxy, octyloxy, isooctyloxy, nonyloxy, decyloxy, etc.
  • halogen encompasses F, Cl, Br, I.
  • the substituent is halogen or cyano.
  • the content of each component in the electrolyte is based on the total weight of the electrolyte.
  • the electrolyte of the present invention contains at least one sulfonic anhydride compound having formula I, formula II or formula III:
  • R 1 to R 18 are each independently selected from hydrogen, halogen, substituted or unsubstituted C 1 -C 7 alkyl substituted or unsubstituted C 2 -C 7 alkenyl, substituted or unsubstituted C 2 -C 7 Alkynyl, substituted or unsubstituted C 6 -C 10 aryl, substituted or unsubstituted C 1 -C 7 alkoxy, or substituted or unsubstituted C 6 -C 10 aryloxy; and where substituted The substituent is halogen or cyano.
  • R 1 to R 18 are each independently selected from hydrogen, halogen, substituted or unsubstituted C 1 -C 4 alkyl, substituted or unsubstituted C 2 -C 4 alkenyl, substituted or unsubstituted C 2 -C 4 alkynyl, substituted or unsubstituted C 6 -C 10 aryl, substituted or unsubstituted C 1 -C 4 alkoxy or substituted or unsubstituted C 6 -C 10 aryloxy; and Wherein, when substituted, the substituent is halogen or cyano.
  • R 1 to R 18 are each independently selected from H, F, methyl, difluoromethyl, trifluoromethyl, ethyl, propyl, vinyl, 1-propenyl, 2-propenyl , 1-propynyl, 2-propynyl, methoxy, ethoxy or phenoxy.
  • the sulfonic anhydride compound includes at least one of the following compounds:
  • the mass fraction of the sulfonic anhydride compound in the electrolyte is from about 0.1% by weight to about 3% by weight, from about 0.2% by weight to about 2% by weight, from about 0.3% by weight to about 1.5% by weight Or about 0.5% to about 1% by weight.
  • the electrolyte solution further includes a fluorinated additive
  • the fluorinated additive includes a fluorinated ether having 2 to 7 carbon atoms, a fluorocarboxylic acid ester having 2 to 6 carbon atoms, or a fluorinated carboxylic acid ester having 2 to 6 carbon atoms. At least one of fluorocarbonic acid esters to 6.
  • the fluorinated additive is selected from at least one of the following compounds: ethyl methyl fluorocarbonate, dimethyl fluorocarbonate, diethyl fluorocarbonate, ethyl fluoropropionate , Propyl fluoropropionate, methyl fluoropropionate, ethyl fluoroacetate, methyl fluoroacetate or propyl fluoroacetate.
  • the fluorinated additive is selected from at least one of the following compounds:
  • the mass ratio P of the fluorinated additive to the sulfonic anhydride compound is about 1 to about 50, about 5 to about 40, or about 10 to about 30.
  • the mass fraction of the fluorinated additive in the electrolyte is not less than about 5% by weight.
  • the mass fraction of the fluorinated additive in the electrolyte is about 5 wt% to about 50 wt%, about 5.5 wt% to about 40 wt%, about 6 wt% to about 30 wt% , About 6.5% to about 20% by weight or about 7% to about 10% by weight.
  • the electrolyte further includes additive A, wherein the additive A includes vinylene carbonate (VC), 1,3-propane sultone (PS), vinyl sulfate (DTD), butylene At least one of dinitrile (BDN) or adiponitrile (ADN).
  • the mass fraction of the vinylene carbonate in the electrolyte is not more than about 2% by weight.
  • the mass fraction of the adiponitrile in the electrolyte is about 0.5% to about 5% by weight.
  • the mass fraction of the succinonitrile in the electrolyte is about 0.5% to about 5% by weight.
  • the mass fraction of the additive A in the electrolyte is about 0.1% to about 10% by weight.
  • the electrolyte further includes a lithium salt and an organic solvent.
  • the lithium salt is selected from one or more of inorganic lithium salt and organic lithium salt. In some embodiments, the lithium salt contains at least one of fluorine, boron, or phosphorus. In some embodiments, the lithium salt is selected from one or more of the following lithium salts: lithium hexafluorophosphate LiPF 6 , lithium bistrifluoromethanesulfonimide LiN (CF 3 SO 2 ) 2 (LiTFSI), bis( Lithium fluorosulfonyl)imide Li(N(SO 2 F) 2 ) (LiFSI), bisoxalic acid borate LiB(C 2 O 4 ) 2 (LiBOB), difluorooxalic acid borate LiBF 2 (C 2 O 4 ) (LiDFOB ), at least one of lithium hexafluoroarsenate (LiAsF 6 ), lithium perchlorate (LiClO 4 ), and lithium trifluoromethanesulfonate (
  • the concentration of the lithium salt is about 0.5 mol/L to about 2 mol/L. In some embodiments, the concentration of the lithium salt is about 0.8 mol/L to about 1.5 mol/L. In some embodiments, the concentration of the lithium salt is about 1 mol/L to about 1.2 mol/L. In some embodiments, the concentration of the lithium salt is about 1.05 mol/L.
  • the organic solvent includes a cyclic ester and a chain ester, and the cyclic ester is selected from at least one of ethylene carbonate (EC), propylene carbonate (PC), ⁇ -butyrolactone (BL) and butylene carbonate One; the chain ester is selected from dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), propyl ethyl carbonate, methyl formate (MF), ethyl formate ( At least one of MA), ethyl acetate (EA), ethyl propionate (EP), propyl propionate (PP), methyl propionate, methyl butyrate, and ethyl butyrate.
  • DMC dimethyl carbonate
  • DEC diethyl carbonate
  • EMC ethyl methyl carbonate
  • MF methyl formate
  • MA ethyl formate
  • MA ethyl acetate
  • EP
  • the mass fraction of the organic solvent in the electrolyte is about 40% to about 60% by weight.
  • the electrochemical device of the present application includes any device that undergoes 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 is an electrochemical device having a positive electrode having a positive electrode active material capable of occluding and releasing metal ions, and a negative electrode having a negative electrode active material capable of occluding and releasing metal ions. Its characteristics are It consists of any of the above-mentioned electrolytes of the present application.
  • the electrolyte used in the electrochemical device of the present application is any of the above-mentioned electrolytes in the present application.
  • the electrolytic solution used in the electrochemical device of the present application may also include other electrolytic solutions within the scope not departing from the gist of the present application.
  • the material, composition, and manufacturing method of the negative electrode used in the electrochemical device of the present application may include any technology related to the silicon-containing negative electrode disclosed in the prior art.
  • the negative electrode active material may also include any negative electrode material selected from graphite, hard carbon, mesocarbon microspheres, etc., which can achieve deintercalation of lithium.
  • the silicon-containing compound is a silicon compound SiO x (0.5 ⁇ x ⁇ 1.5), a simple substance of silicon, or a mixture of the two.
  • the surface of the silicon-containing compound contains Me y O z , 1 ⁇ y ⁇ 2, 1 ⁇ Z ⁇ 3, where Me can be selected from Ti, Al, Zr, and Zn.
  • the metal oxide Me y O z on the surface of the silicon material may be at least one of TiO 2 , Al 2 O 3 , ZrO 2 , and ZnO.
  • the thickness of the metal oxide Me y O z is about 5 nanometers to about 100 nanometers, about 10 nanometers to about 80 nanometers, about 20 nanometers to about 60 nanometers, or about 30 nanometers to about 50 nanometers; metal oxide If the material is too thick, the electronic conductivity on the surface of the material is too poor, which will lead to a larger impedance of the negative electrode, and it is not conducive to the film-forming reaction of the electrolyte additive on the surface of the silicon material to form a protective layer; the metal oxide is too thin to form an effective protection Floor.
  • the mass fraction of the silicon-containing negative active material is about 1 wt% to about 90 wt%, about 5 wt% to about 80 wt% , About 10% by weight to about 70% by weight, about 15% by weight to about 60% by weight, about 20% by weight to about 50% by weight, or about 30% by weight to about 40% by weight.
  • the negative active material further includes carbon nanotubes, the carbon nanotubes have a tube diameter of about 1 nanometer to about 10 nanometers, and a tube length of about 1 micrometer to about 50 micrometers.
  • the mass ratio of the silicon-containing compound to the carbon nanotubes is about 50 to about 300, about 100 to about 250, or about 150 to about 200.
  • the load of the negative active material on the negative electrode is about 10 mg/cm 2 to about 30 mg/cm 2 , about 12 mg/cm 2 to about 25 mg/cm 2 , or about 16 mg/cm 2 To about 20mg/cm 2 .
  • the negative active material may further include a binder, and optionally a conductive material.
  • the binder improves the bonding of the negative active material particles with each other and the bonding of the negative active material with the current collector.
  • the binder includes, but is not limited to: polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, diacetyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyfluoro Ethylene, ethylene oxide-containing polymers, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, styrene butadiene rubber, acrylic (ester) styrene butadiene Rubber, epoxy resin, nylon, etc.
  • conductive materials include, but are not limited to: carbon-based materials, metal-based materials, conductive polymers, or mixtures thereof.
  • the carbon-based material is selected from natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, carbon fiber, or any combination thereof.
  • the metal-based material is selected from metal powder, metal fiber, copper, nickel, aluminum, silver.
  • the conductive polymer is a polyphenylene derivative.
  • the current collector includes, but is not limited to: copper foil, nickel foil, stainless steel foil, titanium foil, foamed nickel, foamed copper, conductive metal-coated polymer substrate, and any combination thereof.
  • the negative electrode can be prepared by a preparation method known in the art.
  • the negative electrode can be obtained by mixing an active material, a conductive material, and a binder in a solvent to prepare an active material composition, and coating the active material composition on a current collector.
  • the solvent may include water and the like, but is not limited thereto.
  • the material of the positive electrode used in the electrochemical device of the present application can be prepared using materials, structures, and manufacturing methods known in the art.
  • the technology described in US9812739B can be used to prepare the positive electrode of the present application, which is incorporated into the present application by reference in its entirety.
  • the positive electrode includes a current collector and a positive electrode active material layer on the current collector.
  • the positive electrode active material includes at least one lithiated intercalation compound that reversibly intercalates and deintercalates lithium ions.
  • the positive active material includes a composite oxide.
  • the composite oxide contains lithium and at least one element selected from cobalt, manganese, and nickel.
  • the positive electrode active material is selected from one or more of lithium cobaltate, lithium manganate, lithium nickelate, or lithium nickel manganese cobalt ternary materials
  • the negative electrode active material contains silicon or silicon oxide materials, It can also be selected from graphite, hard carbon, mesocarbon microspheres, and any other negative electrode materials that can achieve deintercalation of lithium.
  • the positive active material may have a coating on its surface, or may be mixed with another compound having a coating.
  • the coating may include at least one selected from the oxide of the coating element, the hydroxide of the coating element, the oxyhydroxide of the coating element, the oxycarbonate of the coating element, and the hydroxycarbonate of the coating element.
  • the compound used for the coating may be amorphous or crystalline.
  • the coating element contained in the coating may include Mg, Al, Co, K, Na, Ca, Si, Ti, V, Sn, Ge, Ga, B, As, Zr, or any of them. combination.
  • the coating can be applied by any method as long as the method does not adversely affect the performance of the positive electrode active material.
  • the method may include any coating method known in the art, such as spraying, dipping, and the like.
  • the positive active material layer further includes a binder, and optionally a conductive material.
  • the binder improves the bonding of the positive electrode active material particles to each other, and also improves the bonding of the positive electrode active material to the current collector.
  • the binder includes, but is not limited to: polyvinyl alcohol, hydroxypropyl cellulose, diacetyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, ethylene-containing Oxygen polymers, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, styrene butadiene rubber, acrylic (ester) styrene butadiene rubber, epoxy resin, Nylon etc.
  • conductive materials include, but are not limited to: carbon-based materials, metal-based materials, conductive polymers, and mixtures thereof.
  • the carbon-based material is selected from natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, carbon fiber, or any combination thereof.
  • the metal-based material is selected from metal powder, metal fiber, copper, nickel, aluminum, silver.
  • the conductive polymer is a polyphenylene derivative.
  • the current collector may be aluminum, but is not limited thereto.
  • the positive electrode can be prepared by a preparation method known in the art.
  • the positive electrode can be obtained by mixing an active material, a conductive material, and a binder in a solvent to prepare an active material composition, and coating the active material composition on a current collector.
  • the solvent may include N-methylpyrrolidone and the like, but is not limited thereto.
  • the positive electrode is made by forming a positive electrode material using a positive electrode active material layer including lithium transition metal-based compound powder and a binder on a current collector.
  • the positive active material layer can usually be made by the following operations: dry mixing the positive electrode material and the binder (conducting material and thickener used as needed) to form a sheet, The obtained 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, which is coated on the positive electrode current collector and dried.
  • the material of the positive active material layer includes any material known in the art.
  • the electrochemical device of the present application is provided with a separator between the positive electrode and the negative electrode to prevent short circuits.
  • the material and shape of the isolation membrane used in the electrochemical device of the present application are not particularly limited, and it may be any technology disclosed in the prior art.
  • the isolation membrane includes a polymer or an inorganic substance formed of a material that is stable to the electrolyte of the present application.
  • the isolation film may include a substrate layer and a surface treatment layer.
  • the substrate layer is a non-woven fabric, film or composite film with a porous structure, and the material of the substrate layer is selected from at least one of polyethylene, polypropylene, polyethylene terephthalate and polyimide.
  • a polypropylene porous film, a polyethylene porous film, a polypropylene non-woven fabric, a polyethylene non-woven fabric, or a polypropylene-polyethylene-polypropylene porous composite film can be selected.
  • the substrate layer can be one layer or multiple layers. When the substrate layer is multiple layers, the polymer composition of different substrate layers can be the same or different, and the weight average molecular weight is different; when the substrate layer is multiple layers , The closed cell temperature of the polymer of different substrate layers is different.
  • a surface treatment layer is provided on at least one surface of the substrate layer.
  • the surface treatment layer may be a polymer layer or an inorganic substance layer, or a layer formed by a mixed polymer and an inorganic substance.
  • the inorganic layer includes inorganic particles and a binder.
  • the inorganic particles are selected from alumina, silica, magnesium oxide, titanium oxide, hafnium dioxide, 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, polyvinyl ether, One or a combination of polymethyl methacrylate, polytetrafluoroethylene and polyhexafluoropropylene.
  • the polymer layer contains a polymer, and the material of the polymer includes polyamide, polyacrylonitrile, acrylate polymer, polyacrylic acid, polyacrylate, polyvinylpyrrolidone, polyvinyl ether, polyvinylidene fluoride or poly( At least one of vinylidene fluoride-hexafluoropropylene).
  • the electrolyte solution according to the embodiment of the present application can be used to improve the cycle performance of the battery and the high temperature stability characteristics under over-discharge conditions, and is suitable for use in electronic equipment including electrochemical devices.
  • the use of the electrochemical device of the present application is not particularly limited, and it can be used for various known uses.
  • notebook computers pen-input computers, mobile computers, e-book players, portable phones, portable fax machines, portable copiers, portable printers, headsets, video recorders, LCD TVs, portable cleaners, portable CD players, Mini discs, transceivers, electronic notebooks, calculators, memory cards, portable recorders, radios, backup power supplies, motors, cars, motorcycles, assisted bicycles, bicycles, lighting equipment, toys, game consoles, clocks, power tools, flashlights , Cameras, large household storage batteries or lithium-ion capacitors, etc.
  • ethylene carbonate (EC): propylene carbonate (PC): diethyl carbonate (DEC) 20: 10: 70 and mix by mass, and add LiPF 6 as lithium Salt, add specific types and amounts of additives (the types and amounts of added substances are shown in Table 1).
  • the concentration of LiPF 6 in the electrolyte is 1.05 mol/L.
  • Example 1 to Example 20, and Comparative Example 1 and Comparative Example 2
  • the electrolytes and lithium ion batteries of Examples 1 to 20 and Comparative Examples 1 and 2 were prepared according to the above methods (1) to (5).
  • the electrolyte and lithium ion battery of Example 21 were prepared, wherein the negative electrode was prepared according to the method described in the following paragraph, and the others were prepared according to the above-mentioned methods (2) to (5).
  • the electrolyte and lithium ion battery of Example 22 were prepared, wherein the negative electrode was prepared according to the method described in the following paragraph, and the others were prepared according to the above-mentioned methods (2) to (5).
  • the lithium-ion battery Place the lithium-ion battery at 25°C for 30 minutes, then charge at a constant current of 0.5C to a voltage of 4.45V, then charge at a constant voltage of 4.45V to a current of 0.05C, stand for 5 minutes, and then charge at a constant current of 0.5C.
  • the current is discharged to a voltage of 3.0V, which is a charge-discharge cycle process.
  • the discharge capacity this time is the first discharge capacity of the lithium-ion battery.
  • the lithium ion battery was subjected to 500 cycles of charge and discharge test in the above manner, and the discharge capacity of the Nth cycle was detected.
  • Li-ion battery capacity retention rate after N cycles (%) discharge capacity at the Nth cycle/first discharge capacity ⁇ 100%
  • Thickness expansion rate of lithium-ion battery after X days of storage (battery thickness on day X of storage/battery thickness after overdischarge-1) ⁇ 100%
  • Example 1 and Comparative Example 1 According to the test results of Example 1 and Comparative Example 1, it can be seen that for batteries using a silicon-oxygen negative electrode coated with a protective layer of metal oxide (such as Al 2 O 3 ), a sulfonic anhydride compound (such as compound 2) is added to the electrolyte.
  • a sulfonic anhydride compound such as compound 2
  • the cycle capacity retention rate can be significantly improved; and when the battery is discharged to 1.5V, the gas production of the battery can be significantly suppressed.
  • the protective layer has good adhesion to the silicon surface coating layer and can significantly inhibit capacity degradation;
  • the content of the acid anhydride compound (such as compound 2) is too low to form sufficient protection; while the content is too high, the protective layer formed will have too high impedance, which is not conducive to the extraction and insertion of lithium ions.
  • the amount of the sulfonic anhydride compound added is 0.5% by weight to 2% by weight, and the improvement effect is particularly significant.
  • Example 4 According to the test results of Example 4 and Examples 7 to 10, it can be known that the addition of various examples of the sulfonic anhydride compound (for example, compound 2, 4, 5, 7 or 12) to the electrolyte can achieve similar technical effects.
  • the sulfonic anhydride compound for example, compound 2, 4, 5, 7 or 12
  • Example 1 and Examples 2, 12, and 14 it can be seen that adding a proper amount of fluorinated additives (such as compounds 13, 15 and 19) to the electrolyte can further improve the cycle performance of lithium-ion batteries containing silicon anodes, but After the cycle, the high temperature resistance is slightly reduced. This may be due to the fact that fluorinated additives are easy to form an organic protective layer on the silicon surface, which can significantly improve the cycle capacity retention rate, but the high temperature resistance of the organic protective layer is slightly reduced.
  • fluorinated additives are easy to form an organic protective layer on the silicon surface, which can significantly improve the cycle capacity retention rate, but the high temperature resistance of the organic protective layer is slightly reduced.
  • the surface of the silicon negative electrode contains Me y O z (such as Al 2 O) with a thickness of about 10 nanometers to about 80 nanometers. 3 ) It can significantly improve the cycle capacity retention rate of the battery and the high temperature resistance of the battery under over-discharge.
  • the sulfonic anhydride compound can be reduced on the negative electrode to form a protective layer, and the protective layer has strong polarity and can stably adhere to the Me y O z coating layer, thereby achieving the effect of protecting the negative electrode interface more stably ;
  • the thickness of Me y O z is thin, the protection may be insufficient, and the thicker coating layer has poor conductivity and large resistance, so the performance is slightly deteriorated. Based on the above factors, the thickness of Me y O z is between 20 nanometers and 50 nanometers.
  • Example 2 shows that when an appropriate amount of sulfonic anhydride compound is added to the electrolyte and the surface of the negative electrode is coated with a Me y O z protective layer of appropriate thickness, adding carbon nanotubes to the negative electrode can be The conductive network of the negative electrode is further improved, thereby improving the uniformity of the protective layer film formation and reducing the resistance of the negative electrode, thereby further improving the cycle performance of the battery.
  • references to “some embodiments”, “partial embodiments”, “one embodiment”, “another example”, “examples”, “specific examples” or “partial examples” throughout the specification mean At least one embodiment or example in this application includes the specific feature, structure, material, or characteristic described in the embodiment or example. Therefore, descriptions appearing in various places throughout the specification, such as: “in some embodiments”, “in embodiments”, “in one embodiment”, “in another example”, “in an example “In”, “in a specific example” or “exemplary”, which are not necessarily quoting the same embodiment or example in this application.
  • the specific features, structures, materials, or characteristics herein can be combined in one or more embodiments or examples in any suitable manner.

Abstract

本申请提供了一种电解液及电化学装置。本申请的电解液包括磺酸酐化合物,能够显著改善硅负极电化学装置的循环寿命和过放电下产气的问题，使得电化学装置具有优良的循环性能及在过放电条件下的高温稳定特性。

Description

一种电解液及电化学装置 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。
背景技术
锂离子电池具有高能量密度，工作电压高、自放电率低、循环寿命长、无污染等优点，已被广泛应用于计算机、智能穿戴设备、智能手机、无人机，以及电动汽车等领域。随着现代信息技术的发展和锂离子电池应用范围的拓展，本领域锂离子电池的续航能力有了更高的要求。
影响锂离子电池的续航能力的因素有很多。使用硅负极替代传统的石墨负极被认为是进一步提升锂离子电池能量密度的有效手段。然而，硅负极在充放电过程中会发生较大的体积膨胀，硅材料表面保护层破坏，负极与电解液的副反应加剧，造成电池产气和电池容量快速衰减。如何解决上述问题以提高锂离子电池的续航能力已成为本领域目前亟需解决的问题。
发明内容
本发明提供了一种电解液和包含该电解液的电化学装置。该电解液能在硅负极表面生成稳定的保护层，该保护层在过放电条件下不易产气，且能稳定的附着在硅负极上，从而抑制了电解液在硅负极上的副反应，改善了硅负极锂离子电池的循环寿命和过放电下产气的问题。
在一些实施例中，本发明提供了一种电化学装置，包括正极，负极及电解液；其中
所述负极包含负极活性材料层，所述负极活性材料层包含负极活性材料，所述负极活性材料包括含硅化合物；
所述负极活性材料表面还包含保护层，所述保护层含有具有S＝O键的化合物。
在一些实施例中，，其中所述电解液含有至少一种具有式I、式II或式III的磺酸酐化合物：
Figure PCTCN2019128852-appb-000001
其中，R 1至R 18各自独立选自氢、卤素、经取代或未取代的C 1-C 7烷基、经取代或未取代的C 2-C 7烯基、经取代或未取代的C 2-C 7炔基、经取代或未取代的C 6-C 10芳基、经取代或未取代的C 1-C 7烷氧基或经取代或未取代的C 6-C 10芳氧基；且
其中经取代时取代基是卤素或氰基。
在一些实施例中，所述磺酸酐化合物包含下述化合物中的至少一种：
Figure PCTCN2019128852-appb-000002
在一些实施例中，其中所述磺酸酐化合物占所述电解液的质量分数为约0.1重量％至约2重量％。
在一些实施例中，其中以所述负极活性材料的总质量计，所述含硅化合物的质量分数为约1重量％至约90重量％。
在一些实施例中，其中所述负极活性材料层包含碳纳米管，所述碳纳米管的管径为约1纳米至约10纳米、管长为约1微米至约50微米。
在一些实施例中，其中所述含硅化合物与所述碳纳米管的质量比为约50至约300。
在一些实施例中，其中所述含硅化合物的表面含有氧化物Me yO z，1≤y≤2、1≤Z≤3，Me选自Ti、Al、Zr或Zn中的至少一种。
在一些实施例中，其中所述负极活性材料层在所述负极的负载量为约10mg/cm 2至约30mg/cm 2。
在一些实施例中，其中所述电解液进一步包含氟代添加剂，所述氟代添加剂包含碳原子2至7的氟代醚、碳原子数2至6的氟代羧酸酯或碳原子数量2至6的氟代碳酸酯中的至少一种。
在一些实施例中，其中所述氟代添加剂选自下述化合物中的至少一种：氟代碳酸甲乙酯、氟代碳酸二甲酯、氟代碳酸二乙酯、氟代丙酸乙酯、氟代丙酸丙酯、氟代丙酸甲酯、氟代乙酸乙酯、氟代乙酸甲酯或氟代乙酸丙酯。
在一些实施例中，其中所述氟代添加剂占所述电解液的质量分数为不小于约2重量％。
在一些实施例中，其中所述氟代添加剂占所述电解液的质量分数为约2重量％至约50重量％。
在一些实施例中，其中所述氟代添加剂选自下述化合物中的至少一种：
Figure PCTCN2019128852-appb-000003
在一些实施例中，其中所述电解液进一步包含添加剂A，所述添加剂A包含碳酸亚乙烯 酯、1,3-丙烷磺内酯、硫酸乙烯酯、丁二腈或己二腈中的至少一种。
在一些实施例中，其中所述添加剂A占所述电解液的质量分数为约0.1重量％至约10重量％、约0.5重量％至约8重量％、约1重量％至约6重量％、或约2重量％至约4重量％。
在一些实施例中，其中所述氟代添加剂与所述磺酸酐化合物的质量比P满足：约1<P<约50。
在一些实施例中，其中所述负极活性材料进一步包含石墨，所述石墨与所述含硅化合物的质量比为约95:5至约30:70。
在另一个实施例中，本申请提供了一种电子装置，所述电子装置包括如上所述的电化学装置。
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
图1是对比例1和实施例1锂离子电池的负极材料进行红外分析的结果。
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。本申请的实施例不应该被解释为对本申请要求保护范围的限制。除非另外明确指明，本文使用的下述术语具有下文指出的含义。
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％、或小于或等于±0.01％。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”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”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”或“A或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”或“A、B或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。
在具体实施方式及权利要求书中，在关于碳数的表述即大写字母“C”后面的数字，例如“C 1-C 10”、“C 3-C 10”等中，在“C”之后的数字例如“1”、“3”或“10”表示具体官能团中的碳数。即，官能团分别可包括1-10个碳原子和3-10个碳原子。例如，“C 1-C 4烷基”是指具有1-4个碳原子的烷基，例如CH 3-、CH 3CH 2-、CH 3CH 2CH 2-、(CH 3) 2CH-、CH 3CH 2CH 2CH 2-、CH 3CH 2CH(CH 3)-或(CH 3) 3C-。
如本文所用，术语“烷基”预期是具有1至7个碳原子的直链饱和烃结构。“烷基”还预期是具有3至7个碳原子的支链或环状烃结构。例如，烷基可为1至5个碳原子的烷基、或1至4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2-7个碳原子，例如可以为2～5个碳原子的烯基、或2～4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“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至7个、2至5个、或2至4个碳原子的炔基。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。另外，炔基可以是任选地被取代的。
术语“芳基”涵盖单环系统和多环系统。多环可以具有其中两个碳为两个邻接环(所述环是“稠合的”)共用的两个或更多个环，其中所述环中的至少一者是芳香族的，例如其它环可以是环烷基、环烯基、芳基、杂环和/或杂芳基。例如，芳基可为含有6至10个碳原子的。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。另外，芳基可以是任选地被取代的。
术语“芳氧基”表示通过氧桥连接的具有所述碳原子数目的芳基。其中芳基基团具有如本发明所述的含义，这样的实例包括但并不限于苯氧基，对甲苯氧基，对乙苯氧基等。
如本文所用，术语“烷氧基”指的是烷基与氧原子相连形成的基团。其中烷基基团具有如本发明所述的含义。代表性烷氧基实例包括(但不限于)甲氧基、乙氧基、正丙氧基、异丙氧基、正丁氧基、仲丁氧基、叔丁氧基、戊氧基、异戊氧基或叔戊氧基、庚氧基、辛氧基、异辛氧基、壬氧基、癸氧基等。
如本文所用，术语“卤素”涵盖F、Cl、Br、I。
当上述取代基经取代时，取代基为卤素或氰基。
如本文中所使用，电解液中各组分的含量均为基于电解液的总重量得到的。
一、电解液
在一些实施例中，本发明电解液含有至少一种具有式I、式II或式III的磺酸酐化合物：
Figure PCTCN2019128852-appb-000004
其中，R 1至R 18各自独立选自氢、卤素、取代或未取代的C 1-C 7烷基取代或未取代的 C 2-C 7烯基、取代或未取代的C 2-C 7炔基、取代或未取代的C 6-C 10芳基、取代或未取代的C 1-C 7烷氧基、或取代或未取代的C 6-C 10芳氧基；且其中经取代时取代基是卤素或氰基。
在一些实施例中，R 1至R 18各自独立选自氢、卤素、取代或未取代的C 1-C 4烷基、取代或未取代的C 2-C 4烯基、取代或未取代的C 2-C 4炔基，取代或未取代的C 6-C 10芳基、取代或未取代的C 1-C 4烷氧基或取代或未取代的C 6-C 10芳氧基；且其中经取代时取代基是卤素或氰基。
在一些实施例中，R 1至R 18各自独立选自H、F、甲基、二氟甲基、三氟甲基、乙基、丙基、乙烯基、1-丙烯基、2-丙烯基、1-丙炔基、2-丙炔基、甲氧基、乙氧基或苯氧基。
在一些实施例中，所述磺酸酐化合物包含下述化合物中的至少一种：
Figure PCTCN2019128852-appb-000005
在一些实施例中，其中所述磺酸酐化合物占所述电解液的质量分数为约0.1重量％至约3重量％、约0.2重量％至约2重量％、约0.3重量％至约1.5重量％或约0.5重量％至约1重量％。
在一些实施例中，其中所述电解液进一步包含氟代添加剂，所述氟代添加剂包含碳原子2至7的氟代醚、碳原子数2至6的氟代羧酸酯或碳原子数量2至6的氟代碳酸酯中的至少一种。 在一些实施例中，其中所述氟代添加剂选自下述化合物中的至少一种：氟代碳酸甲乙酯、氟代碳酸二甲酯、氟代碳酸二乙酯、氟代丙酸乙酯、氟代丙酸丙酯、氟代丙酸甲酯、氟代乙酸乙酯、氟代乙酸甲酯或氟代乙酸丙酯。
在一些实施例中，其中所述氟代添加剂选自下述化合物中的至少一种：
Figure PCTCN2019128852-appb-000006
在一些实施例中，其中所述氟代添加剂与所述磺酸酐化合物的质量比P为约1至约50、约5至约40、或约10至约30。
在一些实施例中，其中所述氟代添加剂占所述电解液的质量分数为不小于约5重量％。
在一些实施例中，其中所述氟代添加剂占所述电解液的质量分数为约5重量％至约50重量％、约5.5重量％至约40重量％、约6重量％至约30重量％、约6.5重量％至约20重量％或约7重量％至约10重量％。在一些实施例中，其中所述电解液进一步包含添加剂A，其中所述添加剂A包含碳酸亚乙烯酯(VC)、1,3-丙烷磺内酯(PS)、硫酸乙烯酯(DTD)、丁二腈(BDN)或己二腈(ADN)中的至少一种。
在一些实施例中，其中所述碳酸亚乙烯酯占所述电解液的质量分数为不大于约2重量％。
在一些实施例中，其中所述己二腈占所述电解液的质量分数为为约0.5重量％至约5重量％。
在一些实施例中，中所述丁二腈占所述电解液的质量分数为约0.5重量％至约5重量％。
在一些实施例中，所述添加剂A占所述电解液的质量分数为约0.1重量％至约10重量％。
在一些实施例中，所述电解液进一步包括锂盐和有机溶剂。
在一些实施例中，所述锂盐选自无机锂盐和有机锂盐中的一种或多种。在一些实施例中，所述锂盐含有氟元素、硼元素或磷元素中的至少一种。在一些实施例中，所述锂盐选自如下锂盐中的一种或多种：六氟磷酸锂LiPF 6、双三氟甲烷磺酰亚胺锂LiN(CF 3SO 2) 2(LiTFSI)、双(氟磺酰)亚胺锂Li(N(SO 2F) 2)(LiFSI)、双草酸硼酸LiB(C 2O 4) 2(LiBOB)、二氟草酸硼酸LiBF 2(C 2O 4)(LiDFOB)、六氟砷酸锂(LiAsF 6)、高氯酸锂(LiClO 4)、三氟甲磺酸锂(LiCF 3SO 3)中的至少一种。
在一些实施例中，所述锂盐的浓度为约0.5mol/L至约2mol/L。在一些实施例中，所述锂盐的浓度为约0.8mol/L至约1.5mol/L。在一些实施例中，所述锂盐的浓度为约1mol/L至约1.2mol/L。在一些实施例中，所述锂盐的浓度为约1.05mol/L。
所述有机溶剂包含环状酯和链状酯，所述环状酯选自碳酸乙烯酯(EC)、碳酸丙烯酯(PC)、γ-丁内酯(BL)和碳酸丁烯酯中的至少一种；所述链状酯选自碳酸二甲酯(DMC)、碳酸二乙酯(DEC)、碳酸甲乙酯(EMC)、碳酸丙乙酯、甲酸甲酯(MF)、甲酸乙酯(MA)、乙酸乙酯(EA)、丙酸乙酯(EP)、丙酸丙酯(PP)、丙酸甲酯、丁酸甲酯、丁酸乙酯中的至少一种。
在一些实施例中，其中所述有机溶剂占所述电解液的质量分数为约40重量至约60重量％。
二、电化学装置
本申请的电化学装置包括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、太阳能电池或电容器。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是具备具有能够吸留、放出金属离子的正极活性物质的正极以及具有能够吸留、放出金属离子的负极活性物质的负极的电化学装置，其特征在于，包含本申请的上述任何电解液。
电解液
本申请的电化学装置中使用的电解液为本申请的上述任何电解液。此外，本申请的电化学装置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。
负极
本申请的电化学装置中使用的负极的材料、构成和其制造方法可包括任何现有技术中公开的与含硅负极有关的技术。
在一些实施例中，负极包括集流体和位于该集流体上的负极活性材料层，所述负极活性材料层包含负极活性材料，所述负极活性材料包括含硅化合物；所述负极活性材料表面还包含保护层，所述保护层含有具有S＝O键的化合物。
在一些实施例中，所述负极活性材料除了含硅化合物外，还可包含选自石墨、硬碳、中间相碳微球等可实现脱嵌锂的任意负极材料。
在一些实施例中，所述含硅化合物为硅化合物SiO x(0.5＜x＜1.5)、硅单质或二者的混合物。
在一些实施例中，所述含硅化合物表面含有Me yO z，1≤y≤2、1≤Z≤3，其中Me可选自Ti、Al、Zr、Zn。在一些实施例中，硅材料表面金属氧化物Me yO z可为TiO 2、Al 2O 3、ZrO 2、ZnO中的至少一种。
在一些实施例中，金属氧化物Me yO z的厚度为约5纳米至约100纳米、约10纳米至约80纳米、约20纳米至约60纳米或约30纳米至约50纳米；金属氧化物太厚，材料表面的电子导电性太差，会导致负极较大的阻抗，且不利于电解液添加剂在硅材料表面的成膜反应生成保护层；金属氧化物太薄，无法形成有效地保护层。
在一些实施例中，以所述负极活性材料所含物质的总质量计，所述含硅负极活性材料的质量分数为约1重量％至约90重量％、约5重量％至约80重量％、约10重量％至约70重量％、约15重量％至约60重量％、约20重量％至约50重量％、或约30重量％至约40重量％。
在一些实施例中，所述负极活性材料还包含碳纳米管，所述碳纳米管的管径为约1纳米至约10纳米、管长为约1微米至约50微米。
在一些实施例中，所述含硅化合物与所述碳纳米管的质量比为约50至约300、约100至约250、或约150至约200。
在一些实施例中，其中所述负极活性物质在所述负极的负载量为约10mg/cm 2至约30mg/cm 2、约12mg/cm 2至约25mg/cm 2、或约16mg/cm 2至约20mg/cm 2。
在一些实施例中，负极活性材料还可以包括粘合剂，并且可选地包括导电材料。粘合剂提高负极活性材料颗粒彼此间的结合和负极活性材料与集流体的结合。在一些实施例中，粘合剂包括，但不限于：聚乙烯醇、羧甲基纤维素、羟丙基纤维素、二乙酰基纤维素、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、聚偏1,1-二氟乙烯、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。
在一些实施例中，导电材料包括，但不限于：基于碳的材料、基于金属的材料、导电聚合物或它们的混合物。在一些实施例中，基于碳的材料选自天然石墨、人造石墨、碳黑、乙炔黑、科琴黑、碳纤维或其任意组合。在一些实施例中，基于金属的材料选自金属粉、金属纤维、铜、镍、铝、银。在一些实施例中，导电聚合物为聚亚苯基衍生物。
在一些实施例中，集流体包括，但不限于：铜箔、镍箔、不锈钢箔、钛箔、泡沫镍、泡沫铜、覆有导电金属的聚合物基底和它们的任意组合。
负极可以通过本领域公知的制备方法制备。例如，负极可以通过如下方法获得：在溶剂中将活性材料、导电材料和粘合剂混合，以制备活性材料组合物，并将该活性材料组合物涂覆在集流体上。在一些实施例中，溶剂可以包括水等，但不限于此。
正极
本申请的电化学装置中使用的正极的材料可以使用本领域公知的材料、构造和制造方法制备。在一些实施例中，可以采用US9812739B中记载的技术制备本申请的正极，其以全文引用的方式并入本申请中。
在一些实施例中，正极包括集流体和位于该集流体上的正极活性材料层。正极活性材料包括可逆地嵌入和脱嵌锂离子的至少一种锂化插层化合物。在一些实施例中，正极活性材料包括复合氧化物。在一些实施例中，该复合氧化物含有锂以及从钴、锰和镍中选择的至少一种元素。
在一些实施例中，正极活性材料选自钴酸锂、锰酸锂、镍酸锂或锂镍锰钴三元材料中的一种或多种，所述负极活性材料含有硅或硅氧材料，还可任选自石墨、硬碳、中间相碳微球等可实现脱嵌锂的任意负极材料。
在一些实施例中，正极活性材料可以在其表面上具有涂层，或者可以与具有涂层的另一化合物混合。该涂层可以包括从涂覆元素的氧化物、涂覆元素的氢氧化物、涂覆元素的羟基氧化 物、涂覆元素的碳酸氧盐和涂覆元素的羟基碳酸盐中选择的至少一种涂覆元素化合物。用于涂层的化合物可以是非晶的或结晶的。
在一些实施例中，在涂层中含有的涂覆元素可以包括Mg、Al、Co、K、Na、Ca、Si、Ti、V、Sn、Ge、Ga、B、As、Zr或它们的任意组合。可以通过任何方法来施加涂层，只要该方法不对正极活性材料的性能产生不利影响即可。例如，该方法可以包括对本领域公知的任何涂覆方法，例如喷涂、浸渍等。
正极活性材料层还包括粘合剂，并且可选地包括导电材料。粘合剂提高正极活性材料颗粒彼此间的结合，并且还提高正极活性材料与集流体的结合。
在一些实施例中，粘合剂包括，但不限于：聚乙烯醇、羟丙基纤维素、二乙酰基纤维素、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、聚偏1,1-二氟乙烯、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。
在一些实施例中，导电材料包括，但不限于：基于碳的材料、基于金属的材料、导电聚合物和它们的混合物。在一些实施例中，基于碳的材料选自天然石墨、人造石墨、碳黑、乙炔黑、科琴黑、碳纤维或其任意组合。在一些实施例中，基于金属的材料选自金属粉、金属纤维、铜、镍、铝、银。在一些实施例中，导电聚合物为聚亚苯基衍生物。
在一些实施例中，集流体可以是铝，但不限于此。
正极可以通过本领域公知的制备方法制备。例如，正极可以通过如下方法获得：在溶剂中将活性材料、导电材料和粘合剂混合，以制备活性材料组合物，并将该活性材料组合物涂覆在集流体上。在一些实施例中，溶剂可以包括N-甲基吡咯烷酮等，但不限于此。
在一些实施例中，正极通过在集流体上使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可以通过如下操作来制作：将正极材料和粘结剂(根据需要而使用的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，涂布在正极集流体上并进行干燥。在一些实施例中，正极活性物质层的材料包括任何本领域公知的材料。
隔离膜
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离膜以防止短路。本申请的电化学装置中使用的隔离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，隔离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。
例如隔离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。基材层可以为一层或多层，当基材层为多层时，不同的基材层的聚合物的组成可以相同，也可以不同，重均分子量不同；当基材层为多层时，不同的基材层的聚合物的闭孔温度不同。
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、聚乙烯醚、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，聚合物的材料包括聚酰胺、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、聚乙烯醚、聚偏氟乙烯或聚(偏氟乙烯-六氟丙烯)中的至少一种。
三、应用
根据本申请实施例的电解液，能够用于提高电池的循环性能及在过放电条件下的高温稳定特性，适合使用在包含电化学装置的电子设备中。
本申请的电化学装置的用途没有特别限定，可以用于公知的各种用途。例如笔记本电脑、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、家庭用大型蓄电池或锂离子电容器等。
实施例
以下，举出实施例和比较例对本申请进一步具体地进行说明，但只要不脱离其主旨，则本申请并不限定于这些实施例。
一.锂离子电池的制备
(1)负极的制备
称取3.6kg质量分数为1.5重量％的增稠剂羧甲基纤维素钠(CMC)溶液、0.3kg质量分数为50重量％的粘结剂丁苯橡胶乳液、6.0kg石墨粉末负极活性材料、1.2Kg表面包覆有金属氧化物的硅氧负极活性材料SiO(包覆层的成分和厚度如表1所示)、0.012Kg碳纳米管(管径为约1纳米至约5纳米；管长为约1微米至约30微米)；将物料充分混合搅拌得到负极浆料，之后将负极浆料均匀地涂布在厚度为8微米的负极集流体铜箔上，之后在120℃烘烤1小时，得到的负极的活性物质的负载量为约15mg/cm 2，之后经过压实、分切得到负极，制得的负极活性材料层的克容量为约0.55Ah/g。
(2)正极片的制备
称取2.8kg溶剂N-甲基-2-吡咯烷酮(NMP)、2.4kg质量分数为10重量％的粘结剂聚偏二氟乙烯(PVDF)、0.32kg导电剂导电石墨以及14.4kg正极活性材料LiCoO 2充分混合搅拌得到正极浆料，之后将正极浆料均匀地涂布在厚度为10微米的正极集流体铝箔上，之后在120℃烘烤1小时得到正极膜片，之后经过压实、分切得到正极片。
(3)电解液的制备
在干燥的氩气气氛手套箱中，按质量比称取碳酸乙烯酯(EC)：碳酸丙烯酯(PC)：碳酸二乙酯(DEC)＝20：10：70并混合，加入LiPF 6作为锂盐，加入特定种类和量的添加剂(添加的物质种类和量如表1所示)。电解液中LiPF 6的浓度为1.05mol/L。
(4)隔离膜的制备
选用9微米厚的聚丙烯隔离膜
(5)锂离子电池的制备
将上述正极、隔离膜和负极按顺序叠好，使隔离膜处于正极和负极中间，然后卷绕、置于铝箔包装袋中，在80℃烘烤除水后，注入电解液、密封、化成、排气并测试容量得到成品的锂离子二次电池。
实施例1至实施例20，及对比例1和对比例2
按照上述方法(1)至(5)制备实施例1至20及对比例1和对比例2的电解液以及锂离子电池。
实施例21
制备实施例21的电解液以及锂离子电池，其中负极按照下段所述方法制备，其它按照上述方法(2)至(5)制备。
称取3.6kg质量分数为1.5重量％的增稠剂羧甲基纤维素钠(CMC)溶液、0.3kg质量分数为50重量％的粘结剂丁苯橡胶乳液、6.0kg石墨粉末负极活性材料、1.2Kg表面包覆有金属氧化物的硅氧负极活性材料SiO(包覆层的成分和厚度如表1所示)；将物料充分混合搅拌得到负极浆料，之后将负极浆料均匀地涂布在厚度为8微米的负极集流体铜箔上，之后在120℃烘烤1小时，得到的负极的活性物质的负载量为约15mg/cm 2，之后经过压实、分切得到负极。
实施例22
制备实施例22的电解液以及锂离子电池，其中负极按照下段所述方法制备，其它按照上述方法(2)至(5)制备。
称取3.6kg质量分数为1.5重量％的增稠剂羧甲基纤维素钠(CMC)溶液、0.3kg质量分数为50重量％的粘结剂丁苯橡胶乳液、6.0kg石墨粉末负极活性材料、1.2Kg表面无金属氧化物包覆层的硅氧负极活性材料SiO(包覆层的成分和厚度如表1所示)、0.012Kg碳纳米管(管径为约1纳米至约5纳米；管长为约1微米至约30微米)；将物料充分混合搅拌得到负极浆料，之后将负极浆料均匀地涂布在厚度为8微米的负极集流体铜箔上，之后在120℃烘烤1小时，得到的负极的活性物质的负载量为约15mg/cm 2，之后经过压实、分切得到负极。
表1 实施例和对比例
Figure PCTCN2019128852-appb-000007
其中“/”表示未添加该物质。
2.锂离子电池测试
(1)锂离子电池的循环性能测试
在25℃下，将锂离子电池静置30分钟，之后以0.5C恒流充电至电压为4.45V，之后以4.45V恒压充电至电流为0.05C，静置5分钟，之后以0.5C恒流放电至电压为3.0V，此为一个充放电循环过程，此次的放电容量为锂离子电池的首次放电容量。将锂离子电池按上述方式进行500次循环充放电测试，检测得到第N次循环的放电容量。
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/首次放电容量×100％
每个实施例测试三颗电池，数值取其平均值。
(2)锂离子电池过放电存储性能测试
在25℃下，将锂离子二次电池以0.5C恒流充电至电压为4.45V，之后以4.45V恒压 充电至电流为0.05C，静置5分钟，之后以0.5C恒流放电至电压为3.0V，然后以0.05C恒电流放电至电压为1.5V。将放电结束的电池放置到60℃的烘箱中，每隔3天测试一次软包电池厚度，记录锂离子二次电池的厚度膨胀率。每个实施例测试三颗电池，数值取其平均值。
锂离子电池存储X天后厚度膨胀率(％)＝(存储第X天的电池厚度/过放电结束后电池厚度-1)×100％
(3)锂离子电池负极表面红外分析。
将准备好的电池放电，0.5C放电至3.0V,0.05C放电到2.5v。拆解电池，刮取负极活性材料层粉末，压片后进行红外分析。
A.按照上述方法制备实施例1至22和对比例1至2的电解液以及锂离子电池。测试锂离子电池不同循环次数循环容量保持率及放电至1.5V下60℃存储电池厚度膨胀率，测试结果请见表2。
表2 不同循环次数电池容量保持率
Figure PCTCN2019128852-appb-000008
表3 放电至1.5V下60℃存储电池厚度膨胀率
Figure PCTCN2019128852-appb-000009
根据实施例1与对比例1的测试结果可知，对于采用表面包覆有金属氧化物(例如Al 2O 3)保护层的硅氧负极的电池，电解液中添加磺酸酐化合物(例如化合物2)可显著提升循环容量保持率有显著提升；且在放电至1.5V下，能显著抑制电池产气。对实施例1和对比例1的电池负极表面进行红外分析发现(请见图1)，实施例1的负极活性材料表面包含保护层，所述保护层含有具有S＝O键的化合物。对实施例2至22的电池负极表面进行红外分析也确认负极活性材料表面包含保护层，所述保护层含有具有S＝O键的化合物。不希望受任何理论限制，上述性能改善可归因于环状磺酸酐化合物能在负极形成有效的保护层，该保护层在硅表面包覆层的附着性好，能显著抑制容量衰减；当磺酸酐化合物(例如化合物2)的含量太低，不足以形成充分的保护；而含量太高，则形成的保护层阻抗太大，不利于锂离子的脱出和嵌入。综合上述因素，添加的磺酸酐化合物量为0.5重量％至2重量％改善效果尤为显著。
根据实施例4与实施例7至10的测试结果可知，磺酸酐化合物的各个实例(例如化合物2、4、5、7或12)添加到电解液均能获得相似的技术效果。
根据实施例1和实施例2、12及14的测试结果可知，电解液中进一步添加适量氟代添加剂(如化合物13、15和19)可以进一步改善含硅负极的锂离子电池的循环性能，但循环后耐高温性能略有降低。这可能是由于氟代添加剂易于在硅表面形成有机质的保护层，能显著的提升循环容量保持率，但是有机质的保护层耐高温性能略有降低。
根据实施例2及16-19和对比例2的测试结果，当电解液中添加了磺酸酐化合物，在硅负极表面包含厚度为约10纳米至约80纳米的Me yO z(例如Al 2O 3)能显著提升电池的循环容量保持率和过放电下电池耐高温性能。这可归因于磺酸酐化合物能在负极还原形成保护层，而该保护层的极性较强，能稳定的附着在Me yO z包覆层上，从而更稳定地达到保护负极界面的效果；Me yO z的厚度较薄时，可能保护不够充分，而较厚的包覆层导电性较差阻抗较大，从而性能略有变差。综合上述因素，Me yO z的厚度为20纳米至50纳米效果最为理想。
根据实施例2和20的测试结果可知，当电解液中添加了磺酸酐化合物，在硅负极表面含其它Me yO z保护层(例如厚度为20纳米的TiO 2层)，也可以对负极起到较好的保护作用，这是因为金属氧化物TiO 2也具有较强的极性，磺酸酐化合物还原形成的保护层也能稳定地附着在TiO 2表面形成保护；
实施例2和实施例21的对比结果可知：当电解液中添加合适量的磺酸酐化合物，且负极表面包覆合适厚度的Me yO z保护层时，在负极中进一步添加碳纳米管，可进一步改进负极的导电网络，从而改善保护层成膜的均一性，并降低负极阻抗，因而也可以进一步改善电池的循环性能。
以上所述，仅是本发明的几个实施例，并非对本发明做任何形式的限制，虽然本发明以较佳实施例揭示如上，然而并非用以限制本发明，任何熟悉本专业的技术人员，在不脱离本发明技术方案的范围内，利用上述揭示的技术内容做出些许的变动或修饰均等同于等效实施案例，均属于技术方案范围内。
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 (13)

  1. 一种电化学装置，包括正极，负极及电解液；其中
    所述负极包含负极活性材料层，所述负极活性材料层包含负极活性材料，所述负极活性材料包括含硅化合物；
    所述负极活性材料表面还包含保护层，所述保护层含有具有S＝O键的化合物。
  2. 根据权利要求1所述的电化学装置，其中所述电解液含有式I、式II或式III的磺酸酐化合物中的至少一种：
    Figure PCTCN2019128852-appb-100001
    其中，R 1至R 18各自独立选自氢、卤素、经取代或未取代的C 1-C 7烷基、经取代或未取代的C 2-C 7烯基、经取代或未取代的C 2-C 7炔基、经取代或未取代的C 6-C 10芳基、经取代或未取代的C 1-C 7烷氧基或经取代或未取代的C 6-C 10芳氧基；且
    其中经取代时取代基是卤素或氰基。
  3. 根据权利要求2所述的电化学装置，其中所述磺酸酐化合物包含
    Figure PCTCN2019128852-appb-100002
    Figure PCTCN2019128852-appb-100003
    Figure PCTCN2019128852-appb-100004
    中的至少一种；
    其中所述磺酸酐化合物占所述电解液的质量分数为0.01重量％至2重量％。
  4. 根据权利要求1所述的电化学装置，其中以所述负极活性材料的总质量计，所述含硅化合物的质量分数为1重量％至90重量％。
  5. 根据权利要求1所述的电化学装置，其中所述负极活性材料层包含碳纳米管，所述碳纳米管的管径为1纳米至10纳米、管长为1微米至50微米。
  6. 根据权利要求4所述的电化学装置，其中以所述负极活性材料的总质量计，所述含硅化合物与所述碳纳米管的质量比为50至300。
  7. 根据权利要求1所述的电化学装置，其中所述含硅化合物的表面含有Me yO z，1≤y≤2、1≤Z≤3，Me选自Ti、Al、Zr或Zn中的至少一种。
  8. 根据权利要求1所述的电化学装置，其中所述负极活性材料层在所述负极的负载量为10mg/cm 2至30mg/cm 2。
  9. 根据权利要求1所述的电化学装置，其中所述电解液进一步包含氟代添加剂，所述氟代添加剂包含碳原子2至7的氟代醚、碳原子数2至6的氟代羧酸酯或碳原子数量2至6的氟代碳酸酯中的至少一种，其中所述氟代添加剂占所述电解液的质量分数为不小于约2重量％。
  10. 根据权利要求8所述的电化学装置，其中所述氟代添加剂选自氟代碳酸甲乙酯、氟代碳酸二甲酯、氟代碳酸二乙酯、氟代丙酸乙酯、氟代丙酸丙酯、氟代丙酸甲酯、氟代乙酸乙酯、氟代乙酸甲酯、氟代乙酸丙酯、
    Figure PCTCN2019128852-appb-100005
    Figure PCTCN2019128852-appb-100006
    中的至少一种。
  11. 根据权利要求1所述的电化学装置，其中所述电解液进一步包含添加剂A，所述添加剂A包含碳酸亚乙烯酯、1,3-丙烷磺内酯、硫酸乙烯酯、丁二腈或己二腈中的至少一种，其中所述添加剂A占所述电解液的质量分数为0.1重量％至10重量％。
  12. 根据权利要求8所述的电化学装置，其中所述氟代添加剂与所述磺酸酐化合物的质量比P满足：1<P<50。
  13. 一种电子装置，其包括根据权利要求1-11中任一权利要求所述的电化学装置。
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