WO2024183071A1 - 电解液、含有其的电池和用电装置 - Google Patents

电解液、含有其的电池和用电装置 Download PDF

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Publication number
WO2024183071A1
WO2024183071A1 PCT/CN2023/080576 CN2023080576W WO2024183071A1 WO 2024183071 A1 WO2024183071 A1 WO 2024183071A1 CN 2023080576 W CN2023080576 W CN 2023080576W WO 2024183071 A1 WO2024183071 A1 WO 2024183071A1
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Prior art keywords
electrolyte
lithium
additive
battery
formula
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PCT/CN2023/080576
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English (en)
French (fr)
Inventor
彭畅
陈培培
黄雨铭
李泽鹏
郑秀
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宁德时代新能源科技股份有限公司
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Priority to PCT/CN2023/080576 priority Critical patent/WO2024183071A1/zh
Publication of WO2024183071A1 publication Critical patent/WO2024183071A1/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
    • H01M10/056—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
    • 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 field of battery technology, and in particular to an electrolyte, a battery containing the electrolyte, and an electrical device.
  • secondary batteries have been widely used in energy storage power systems such as hydropower, thermal power, wind power and solar power stations, as well as power tools, electric bicycles, electric motorcycles, electric vehicles, military equipment, aerospace and other fields due to their high energy density and recyclability.
  • energy storage power systems such as hydropower, thermal power, wind power and solar power stations, as well as power tools, electric bicycles, electric motorcycles, electric vehicles, military equipment, aerospace and other fields due to their high energy density and recyclability.
  • higher requirements have been put forward for their cycle performance, storage life and other properties.
  • the embodiments of the present application provide an electrolyte, a battery containing the same, and an electrical device.
  • the cycle performance and storage life of the battery containing the electrolyte are improved.
  • an electrolyte comprising: a first additive, wherein the first additive comprises at least one of a compound containing at least a group represented by formula (I) and formula (II), and a compound containing at least a group represented by formula (I) and formula (II):
  • R 1 , R 3 and R 4 each independently include at least one of a saturated or unsaturated hydrocarbon group
  • X 1 and X 2 include O or CH 2 and X 1 and X 2 are not CH 2 at the same time.
  • the electrolyte includes a first additive
  • the first additive includes at least one of a compound containing at least the groups shown in formula (I) and formula (II), and a compound containing at least the groups shown in formula (I) and formula ( ⁇ ). That is, the first additive includes at least one of a compound containing both a cyclic phosphate and a cyclic carbonate structure, and a compound containing both a cyclic phosphate and a cyclic sulfate and/or a cyclic sulfonate structure.
  • the first additive undergoes a copolymerization reaction at the electrode interface and participates in the film formation in the battery formation stage.
  • the formed copolymer has the advantages of a polycarbonate polymer and a polyphosphate polymer or a polyphosphate and a polysulfate and/or a polysulfonate.
  • the crystallinity of the copolymer is reduced, the toughness of the formed interface film is also improved, and the stability of the interface film is improved, thereby improving the storage life of the battery.
  • compounds containing both cyclic carbonate and cyclic phosphate structures, and compounds containing both cyclic phosphate and cyclic sulfate and/or cyclic sulfonate structures have larger molecular structures, greater steric hindrance, and weaker solvation capabilities.
  • they have low reaction activity at the electrode plate interface and a slow consumption rate in the electrolyte. They can continuously provide film-forming materials for the battery to repair the interface film between the electrode plate and the electrolyte, thereby reducing the life decay rate of the battery in the middle and late stages of the cycle and improving the cycle stability and service life of the battery.
  • the mass content of the first additive in the electrolyte is 0.0001% to 10%.
  • the mass content of the first additive in the electrolyte is 0.01% to 5%.
  • the content of the first additive in the electrolyte is too little, sufficient copolymers cannot be formed to participate in film formation, affecting the stability of the interface film and resulting in unstable interface between the electrode plate and the electrolyte; if the content of the first additive in the electrolyte is too high, the viscosity of the electrolyte will be too high, affecting the wetting of the electrolyte to the electrode plate and affecting the charge and discharge performance of the battery.
  • the first additive includes at least one of the compounds represented by formula (IV), formula (V), formula (VI), and formula (VII):
  • R5 and R6 each independently include at least one of H, a halogen atom, a substituted or unsubstituted hydrocarbon group, and a group containing an unsaturated double bond or triple bond
  • R7 and R8 each independently include at least one of a saturated or unsaturated hydrocarbon group having a carbon number of 1-6, and a single bond
  • the value of x is any natural number from 1 to 5
  • the value of y is any natural number from 0 to 5.
  • the content of inorganic components in the compounds can be increased to improve the insulation of the interface film; by introducing hydrocarbon groups into the compounds, the stability of the compounds can be improved; by introducing unsaturated double bonds or triple bonds into the end groups of the compounds, the first additive has a multi-functional group structure, which makes it easier to form a cross-linked network structure during the film formation stage, which can better wrap the particle structure of the electrode material and inhibit the expansion of the electrode material, thereby further improving the cycle storage performance.
  • R 5 and R 6 each independently include at least one of H, F, a straight-chain alkyl group or a branched-chain alkyl group having 1 to 3 carbon atoms, a straight-chain perfluoro-substituted alkyl group or a branched-chain perfluoro-substituted alkyl group having 1 to 3 carbon atoms, and a group having 1 to 3 carbon atoms and containing an unsaturated double bond.
  • the structure of the compound of formula (IV), formula (V), formula (VI), and formula (VII) is optimized, so that the first additive has a suitable solubility and viscosity in the electrolyte, can better participate in film formation in the electrolyte, and improve the electrode polarity.
  • the stability of the interfacial film between the film and the electrolyte is optimized, so that the first additive has a suitable solubility and viscosity in the electrolyte, can better participate in film formation in the electrolyte, and improve the electrode polarity.
  • R7 and R8 each independently include at least one saturated or unsaturated hydrocarbon group having 1 to 3 carbon atoms.
  • the number of carbon atoms in the hydrocarbon structure between the multiple ester groups is too large and the hydrocarbon structure is too long, it will affect the compactness of the electrode interface film formed by the first additive.
  • the length of the hydrocarbon structure between the multiple ester groups is made appropriate to form a compact electrode interface film.
  • the first additive includes at least one of the following substances:
  • the electrolyte further includes a second additive, and the second additive includes at least one of carbonate, sulfonate, sulfate, and phosphate.
  • carbonates, sulfonates, sulfates, and phosphates form monomer active free radicals under electrochemical reactions, thereby increasing the reaction conversion rate of the first additive copolymerization to form a copolymer, making the initially formed copolymer interface film larger in molecular weight and denser, further improving the initial film quality.
  • the second additive includes vinylene carbonate, difluoroethylene carbonate, fluoroethylene carbonate, vinyl ethylene carbonate, propane sultone, propenyl-1,3-sultone, vinyl sulfate, vinyl disulfate, tris (2,2,2-trifluoroethyl) phosphate, triallyl phosphate, difluorophosphoric acid At least one of lithium.
  • the electrolyte further includes a third additive, and the third additive includes at least one of SO 2 and CO 2 .
  • At least one of SO2 and CO2 is added to the electrolyte.
  • SO2 and CO2 can change the breaking and bonding form of the first additive in the formation stage, inhibit the first additive from forming SO2 and CO2 in the formation stage, and instead form more inorganic-organic dense interface films containing carbonates, sulfates, and polycarbonate-polyphosphates and/or polysulfates/polysulfonates-polyphosphates, that is, the copolymer contains more sulfate and carbonate structures, making the interface film denser and better preventing the co-embedding of other molecules in the electrolyte, avoiding the damage of the electrode material caused by the co-embedding of other molecules, thereby improving the cycle stability and service life of the battery.
  • the mass content of the third additive in the electrolyte is 10 to 1000 ppm.
  • the electrolyte further includes a polymerization inhibitor.
  • the polymerization inhibitor includes at least one of hydroquinone and 2,6-di-tert-butyl-p-cresol.
  • Hydroquinone and 2,6-di-tert-butyl-p-cresol are added to the electrolyte as inhibitors to reduce the risk of chemical reactions between substances in the electrolyte when they are in full contact during the transportation of the battery, thereby reducing the risk of destruction of the components of the electrolyte.
  • the mass content of the polymerization inhibitor in the electrolyte is less than 20 ppm.
  • the mass content of the polymerization inhibitor in the electrolyte is less than 10 ppm.
  • the content of the inhibitor in the electrolyte should not be too high, otherwise it will inhibit the copolymerization reaction of the first additive, affect the film formation of the battery in the formation stage, and fail to form a stable interface film between the electrode plate and the electrolyte. Controlling the content of the inhibitor can improve the film formation quality of the battery in the formation stage, thereby improving the performance and service life of the battery.
  • the electrolyte further includes a solvent, wherein the solvent is The relative dielectric constant is greater than 2 and the viscosity is less than 2 mPa.s.
  • the solvent includes at least one of carbonate, carboxylate, ether, sulfone, fluorinated carbonate, fluorinated carboxylate, fluorinated ether, and fluorinated sulfone.
  • the electrolyte further includes a metal salt
  • the metal salt includes at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium difluorooxalatoborate, lithium dioxalatoborate, lithium difluorophosphate, lithium difluorobis(oxalatophosphate), and lithium tetrafluorooxalatophosphate.
  • the metal salt includes at least one of lithium hexafluorophosphate and lithium bis(fluorosulfonyl)imide.
  • the acidity of the electrolyte is less than 800 ppm.
  • the first additive may become unstable and degrade, making it difficult to form a copolymer, thus affecting the film quality.
  • a battery comprising: the electrolyte in the above-mentioned first aspect or any possible implementation of the first aspect.
  • an electrical device comprising: the battery in the second aspect or any possible implementation of the second aspect, wherein the battery is used to provide electrical energy.
  • the electrolyte includes a first additive
  • the first additive includes at least one of a compound containing at least the groups shown in formula (I) and formula (II), and a compound containing at least the groups shown in formula (I) and formula (II). That is, the first additive includes at least one of a compound containing both a cyclic phosphate and a cyclic carbonate structure, and a compound containing both a cyclic phosphate and a cyclic sulfate and/or a cyclic sulfonate structure.
  • the first additive undergoes a copolymerization reaction at the electrode interface and participates in the film formation in the battery formation stage.
  • the formed copolymer has the advantages of a polycarbonate polymer and a polyphosphate polymer or a polyphosphate and a polysulfate and/or a polysulfonate.
  • the crystallinity of the copolymer is reduced, the toughness of the formed interface film is also improved, and the stability of the interface film is improved, thereby improving the storage life of the battery.
  • the compounds containing both cyclic carbonate and cyclic phosphate structures, and the compounds containing both cyclic phosphate and cyclic sulfate and/or cyclic sulfonate structures have larger molecular structures, greater steric hindrance, and weaker solvation ability.
  • they have low reaction activity at the electrode plate interface and slow consumption rate in the electrolyte. They can continuously provide film-forming materials for the battery to repair the interface film between the electrode plate and the electrolyte, thereby Reduce the life decay rate of the battery in the middle and late stages of the cycle, and improve the cycle stability and service life of the battery.
  • FIG1 is a schematic diagram of a battery cell disclosed in an embodiment of the present application.
  • FIG2 is a schematic diagram of an exploded structure of a battery cell disclosed in an embodiment of the present application.
  • FIG3 is a schematic diagram of an exploded structure of a battery disclosed in an embodiment of the present application.
  • FIG. 4 is a schematic diagram of an electrical device disclosed in an embodiment of the present application.
  • the reference numerals in the specific implementation manner are as follows: Battery 10 , box body 11 , battery cell 20 , shell 21 , electrode assembly 22 , cover plate 23 .
  • “Scope” disclosed in the present application is limited in the form of lower limit and upper limit, and a given range is limited by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundary of a special range.
  • the scope limited in this way can be including end values or not including end values, and can be arbitrarily combined, that is, any lower limit can be combined with any upper limit to form a scope. For example, if the scope of 60-120 and 80-110 is listed for a specific parameter, it is understood that the scope of 60-110 and 80-120 is also expected.
  • the numerical range "a-b" represents the abbreviation of any real number combination between a and b, wherein a and b are real numbers.
  • the numerical range "0-5" means that all real numbers between "0-5" are listed in this document, and "0-5" is just an abbreviation of these numerical combinations.
  • a parameter is expressed as an integer ⁇ 2, it is equivalent to disclosing that the parameter is, for example, an integer of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.
  • the method includes steps (a) and (b), which means that the method may include steps (a) and (b) performed sequentially, or may include steps (b) and (a) performed sequentially.
  • the method may further include step (c), which means that step (c) may be added to the method in any order.
  • the method may include steps (a), (b) and (c), or may include steps (a), (c) and (b), or may include steps (c), (a) and (b), etc.
  • the “include” and “comprising” mentioned in this application are open-ended or closed-ended.
  • the “include” and “comprising” may mean that other components not listed may also be included or only the listed components may be included or only the listed components may be included.
  • the term "or” is inclusive.
  • the phrase “A or B” means “A, B, or both A and B”. More specifically, any of the following conditions satisfies the condition "A or B”: A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).
  • alkyl refers to a monovalent saturated hydrocarbon group having one or more carbon atoms, optionally with a carbon number of 1 to 18.
  • alkyl includes straight chain alkyl and branched chain alkyl, such as methyl ( CH3- ), ethyl ( CH3CH2- ) , n -propyl ( CH3CH2CH2- ) , isopropyl ( ( CH3 ) 2CH- ), n-butyl ( CH3CH2CH2CH2-), isobutyl ((CH3) 2CHCH2- ) , sec -butyl (( CH3 )( CH3CH2 ) CH- ) , tert-butyl ((CH3 ) 3C- ), n-pentyl ( CH3CH2CH2CH2- ) , neopentyl (( CH3 ) 3CCH2- ), and the like.
  • Perfluoro-substituted alkyl means that all hydrogen atoms in carbon-hydrogen bonds in the alkyl group are replaced by fluorine atoms, such as perfluoro-substituted methyl (CF 3 -), perfluoro-substituted ethyl (CF 3 CF 2 -), perfluoro-substituted n-propyl (CF 3 CF 2 CF 2 -), and perfluoro-substituted isobutyl ((CF 3 ) 2 CFCF 2 -).
  • a secondary battery includes a positive electrode sheet, a negative electrode sheet, an electrolyte, and a separator.
  • active ions are embedded and removed back and forth between the positive electrode sheet and the negative electrode sheet.
  • the electrolyte in the electrolyte plays the role of conducting ions between the positive electrode sheet and the negative electrode sheet.
  • the separator is arranged between the positive electrode sheet and the negative electrode sheet, which prevents the positive and negative electrodes from short-circuiting while allowing ions to pass through, so that the electrochemical reaction of the secondary battery proceeds normally.
  • Secondary batteries may include lithium-ion batteries, sodium-ion batteries, magnesium-ion batteries, etc. This application takes lithium-ion batteries as an example.
  • Lithium-ion batteries are a typical type of secondary batteries. Since they rely on the chemical reaction of lithium ions being embedded and released between the positive and negative electrodes for charging and discharging, lithium-ion batteries are also called rocking-chair batteries. During the charging process of lithium-ion batteries, lithium ions are released from the positive electrode, moved and embedded in the negative electrode; and during the discharging process, lithium ions are released from the negative electrode, moved and embedded in the positive electrode.
  • the film-forming additives in the electrolyte will be reduced to form a solid electrolyte interphase (SEI) film on the surface of the electrode.
  • SEI solid electrolyte interphase
  • the SEI film can prevent the non-aqueous organic solvent in the electrolyte from further decomposing and form ion channels in subsequent charge and discharge cycles.
  • the stability of the SEI film between the electrolyte and the electrode plate will deteriorate, gradually breaking and regenerating, causing the electrolyte to be continuously consumed, affecting the cycle stability and service life of the secondary battery.
  • the present application provides an electrolyte, the electrolyte includes a first additive, the first additive includes at least one of a compound containing at least a group represented by formula (I) and formula (II), and a compound containing at least a group represented by formula (I) and formula ( ⁇ ). That is, the first additive includes at least one of a compound containing both a cyclic phosphate and a cyclic carbonate structure, and a compound containing both a cyclic phosphate and a cyclic sulfate and/or a cyclic sulfonate structure.
  • the first additive undergoes a copolymerization reaction at the electrode interface and participates in the film formation in the battery formation stage.
  • the formed copolymer has the advantages of a polycarbonate polymer and a polyphosphate polymer or a polyphosphate and a polysulfate and/or a polysulfonate.
  • the crystallinity of the copolymer is reduced, the toughness of the formed interface film is also improved, and the stability of the interface film is improved, thereby improving the storage life of the battery.
  • compounds containing both cyclic carbonate and cyclic phosphate structures, and compounds containing both cyclic phosphate and cyclic sulfate and/or cyclic sulfonate structures have larger molecular structures, greater steric hindrance, and weaker solvation capabilities.
  • they have low reaction activity at the electrode plate interface and a slow consumption rate in the electrolyte. They can continuously provide film-forming materials for the battery to repair the interface film between the electrode plate and the electrolyte, thereby reducing the life decay rate of the battery in the middle and late stages of the cycle and improving the cycle stability and service life of the battery.
  • the electrolyte plays a role in conducting ions between the positive electrode and the negative electrode.
  • the electrolyte provided in the present application includes a first additive, specifically, the first additive includes at least one of a compound containing at least a group represented by formula (I) and formula (II), and a compound containing at least a group represented by formula (I) and formula ( ⁇ ):
  • R 1 , R 3 and R 4 each independently include at least one of a saturated or unsaturated hydrocarbon group
  • X 1 and X 2 include O or CH 2 and X 1 and X 2 are not CH 2 at the same time.
  • the first additive includes at least one of a compound containing both a cyclic carbonate and a cyclic phosphate structure, and a compound containing both a cyclic phosphate and a cyclic sulfate and/or a cyclic sulfonate structure.
  • Cyclic carbonates have a high dielectric constant and high ionic conductivity, and can form a stable interface film on the electrode surface. Cyclic phosphates added to the electrolyte can make the electrolyte have good stability and high conductivity, while increasing the safety and flame retardancy of the battery.
  • Cyclic sulfates added to the electrolyte can inhibit the decrease in the initial capacity of the battery, increase the initial discharge capacity, reduce the expansion of the battery after being placed at high temperature, and improve the charge and discharge performance and cycle performance of the battery. Cyclic sulfonates added to the electrolyte can form a stable interface film on the electrode surface.
  • a compound containing cyclic phosphate and cyclic sulfate and/or cyclic sulfonate structures undergoes copolymerization reaction, and the formed copolymer has the advantages of polyphosphate polymer and polysulfate polymer and/or polysulfonate polymer.
  • the electrolyte provided in the embodiment of the present application includes a first additive, and the first additive includes at least one of a compound containing at least the groups shown in formula (I) and formula (II), and a compound containing at least the groups shown in formula (I) and formula (II). That is, the first additive includes at least one of a compound containing both a cyclic phosphate and a cyclic carbonate structure, and a compound containing both a cyclic phosphate and a cyclic sulfate and/or a cyclic sulfonate structure.
  • the first additive undergoes a copolymerization reaction at the electrode interface and participates in the film formation in the battery formation stage.
  • the formed copolymer has the advantages of a polycarbonate polymer and a polyphosphate polymer or a polyphosphate and a polysulfate and/or a polysulfonate.
  • the crystallinity of the copolymer is reduced, the toughness of the formed interface film is also improved, and the stability of the interface film is improved, thereby improving the storage life of the battery.
  • compounds containing both cyclic carbonate and cyclic phosphate structures, and compounds containing both cyclic phosphate and cyclic sulfate and/or cyclic sulfonate structures have larger molecular structures, greater steric hindrance, and weaker solvation capabilities.
  • they have low reaction activity at the electrode plate interface and a slow consumption rate in the electrolyte. They can continuously provide film-forming materials for the battery to repair the interface film between the electrode plate and the electrolyte, thereby reducing the life decay rate of the battery in the middle and late stages of the cycle and improving the cycle stability and service life of the battery.
  • the mass content of the first additive in the electrolyte is 0.0001% to 10%.
  • the mass content of the first additive in the electrolyte is 0.01% to 5%.
  • the mass content of the first additive in the electrolyte can be 0.0001%, 0.0005%, 0.001%, 0.0015%, 0.002%, 0.0025%, 0.003%, 0.0035%, 0.004%, 0.0045%, 0.005%, 0.0055%, 0.006%, 0.0065%, 0.007%, 0.0075%, 0.008%, 0.0085%, 0.009%, 0.0095%, 0.01%, 0.02%, 0.03%, 0.04%, 0.05%, 0.06%, 0.07%, 0.08%, 0.09%, 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 2%, 3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, or any value within the range obtained
  • the first additive includes at least one of the compounds represented by formula (IV), formula (V), formula (VI), and formula (VII):
  • R5 and R6 each independently include at least one of H, a halogen atom, a substituted or unsubstituted hydrocarbon group, and a group containing an unsaturated double bond or triple bond
  • R7 and R8 each independently include at least one of a saturated or unsaturated hydrocarbon group having a carbon number of 1-6, and a single bond
  • the value of x is any natural number from 1 to 5
  • the value of y is any natural number from 0 to 5.
  • the content of inorganic components in the compounds can be increased to improve the insulation of the interface film;
  • Introducing a hydrocarbon group can improve the stability of the compound;
  • introducing an unsaturated double bond or triple bond into the terminal group of the compound makes the first additive have a multi-functional group structure, which is easier to form a cross-linked network structure in the film-forming stage, can better wrap the particle structure of the electrode material, and at the same time can inhibit the expansion of the electrode material, further improving the cycle storage performance.
  • the value of x may be 1 or 2, and the value of y may be 0, 1 or 2.
  • R 5 and R 6 each independently include at least one of H, F, a straight-chain alkyl group or a branched-chain alkyl group having 1-3 carbon atoms, a straight-chain perfluoro-substituted alkyl group or a branched-chain perfluoro-substituted alkyl group having 1-3 carbon atoms, and a group having 1-3 carbon atoms and containing an unsaturated double bond.
  • the number of carbon atoms in the group of the compounds of formula (IV), formula (V), formula (VI), and formula (VII) is adjusted and the structures of the compounds of formula (IV), formula (V), formula (VI), and formula (VII) are optimized so that the first additive has suitable solubility and viscosity in the electrolyte, can better participate in film formation in the electrolyte, and improve the stability of the interface film between the electrode plate and the electrolyte.
  • R7 and R8 each independently include at least one saturated or unsaturated hydrocarbon group having 1 to 3 carbon atoms.
  • the number of carbon atoms in the hydrocarbon structure between the multiple ester groups is too large and the hydrocarbon structure is too long, it will affect the compactness of the electrode interface film formed by the first additive.
  • the length of the hydrocarbon structure between the multiple ester groups is made appropriate to form a compact electrode interface film.
  • the first additive includes at least one of the following substances:
  • the fluorine atom with the strongest electronegativity among the halogens is selected and introduced into the cyclic phosphate structure shown in formula (I), which can further improve the stability and antioxidant properties of the compound containing the cyclic phosphate structure.
  • R2 in the cyclic phosphate structure shown in formula (I) is a fluorine atom.
  • the content of the first additive in the electrolyte is too little, sufficient copolymers cannot be formed to participate in film formation, affecting the stability of the interface film and resulting in unstable interface between the electrode plate and the electrolyte; if the content of the first additive in the electrolyte is too high, the viscosity of the electrolyte will be too high, affecting the wetting of the electrolyte to the electrode plate and affecting the charge and discharge performance of the battery.
  • the electrolyte further includes a second additive, and the second additive includes at least one of carbonate, sulfonate, sulfate, and phosphate.
  • the second additive includes at least one of vinylene carbonate (VC), bisfluoroethylene carbonate (DFEC), fluoroethylene carbonate (FEC), vinylethylene carbonate (VEC), propane sultone, propenyl-1,3-sultone, vinyl sulfate, vinyl bissulfate, tris(2,2,2-trifluoroethyl) phosphate, triallyl phosphate, and lithium difluorophosphate.
  • VC vinylene carbonate
  • DFEC bisfluoroethylene carbonate
  • FEC fluoroethylene carbonate
  • VEC vinylethylene carbonate
  • propane sultone propenyl-1,3-sultone
  • vinyl sulfate vinyl bissulfate
  • tris(2,2,2-trifluoroethyl) phosphate triallyl phosphate
  • lithium difluorophosphate lithium difluorophosphate.
  • carbonates, sulfonates, sulfates, and phosphates form monomer active free radicals under electrochemical reactions, thereby increasing the reaction conversion rate of the first additive copolymerization to form a copolymer, so that the initial formation
  • the copolymer interfacial film has a larger molecular weight and is denser, further improving the initial film quality.
  • the electrolyte further includes a third additive, and the third additive includes at least one of SO 2 and CO 2 .
  • the mass content of the third additive in the electrolyte is 10 to 1000 ppm.
  • Hydroquinone and 2,6-di-tert-butyl-p-cresol are added to the electrolyte as inhibitors to reduce the risk of chemical reactions between substances in the electrolyte when they are in full contact during the transportation of the battery, thereby reducing the risk of destruction of the components of the electrolyte.
  • the mass content of the polymerization inhibitor in the electrolyte is less than 20 ppm.
  • the mass content of the polymerization inhibitor in the electrolyte is less than 10 ppm.
  • the mass content of the inhibitor in the electrolyte can be 15 ppm, 10 ppm, 5 ppm, 4 ppm, 3 ppm, 2 ppm, or 1 ppm.
  • the content of the inhibitor in the electrolyte should not be too high, otherwise it will inhibit the copolymerization reaction of the first additive. It affects the film formation of the battery during the formation stage and cannot form a stable interface film between the electrode plate and the electrolyte. Controlling the content of the inhibitor can improve the film formation quality of the battery during the formation stage, thereby improving the performance and service life of the battery.
  • the electrolyte further includes a solvent, and the relative dielectric constant of the solvent at 25° C. is greater than 2 and the viscosity is less than 2 mPa.s.
  • the relative dielectric constant of the solvent at 25° C. may be 3, 4, 5, or 6; the viscosity of the solvent at 25° C. may be 1.5 mPa.s or 1 mPa.s.
  • the solvent includes at least one of carbonates, carboxylates, ethers, sulfones, fluorinated carbonates, fluorinated carboxylates, fluorinated ethers, and fluorinated sulfones.
  • the solvent of the electrolyte is usually an organic solvent, such as carbonate, carboxylate, ether, sulfone, etc.
  • organic solvents can improve the wettability of the electrolyte to the electrode plate, and have a high dielectric constant, reduce the impedance of the electrode plate embedded with active ions, improve the conductivity, and improve the cycle performance of the battery.
  • the electrolyte further includes a metal salt.
  • the electrolyte of lithium-ion batteries includes lithium salts.
  • the lithium salt includes at least one of lithium hexafluorophosphate (LiPF 6 ), lithium tetrafluoroborate (LiBF 4 ), lithium perchlorate (LiClO 4 ), lithium hexafluoroarsenate (LiAsF 6 ), lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium trifluoromethanesulfonate (LiTFS), lithium difluorooxalatoborate (LiDFOB), lithium dioxalatoborate (LiBOB), lithium difluorophosphate (LiPO 2 F 2 ), lithium difluorobis(oxalatophosphate) (LiDFOP), and lithium tetrafluorooxalatophosphate (LiPF 6 ), lithium tetra
  • Secondary batteries may include lithium ion batteries, sodium ion batteries, magnesium ion batteries, etc.
  • the metal salt may be lithium salt, sodium salt, magnesium salt, etc. It should be understood that the various metal salts provided in the embodiments of the present application are only examples and should not be construed as limiting the metal salts of the present application.
  • the acidity of the electrolyte is less than 800 ppm.
  • the acidity value of the electrolyte may be 700 ppm, 650 ppm, 600 ppm, 550 ppm, or 500 ppm.
  • the acidity value of the electrolyte refers to the mass content of hydrofluoric acid (HF) in the electrolyte, and the free HF in the electrolyte can be titrated using a triethylamine solution standard solution.
  • HF hydrofluoric acid
  • the first additive may become unstable and degrade, making it difficult to form a copolymer, thereby affecting the film quality.
  • a battery cell includes a positive electrode sheet, a negative electrode sheet, an electrolyte and a separator.
  • active ions are embedded and released back and forth between the positive electrode sheet and the negative electrode sheet.
  • the electrolyte in the electrolyte plays the role of conducting ions between the positive electrode sheet and the negative electrode sheet.
  • the separator is arranged between the positive electrode sheet and the negative electrode sheet, mainly to prevent the positive and negative electrodes from short-circuiting, while allowing ions to pass through.
  • the “embedding” process described in this application refers to the process in which active ions are embedded in the positive electrode active material or the negative electrode active material due to an electrochemical reaction
  • the “extraction” and “de-embedding” processes described in this application refer to the process in which active ions are extracted from the positive electrode active material or the negative electrode active material due to an electrochemical reaction.
  • the positive electrode sheet includes a positive electrode current collector and a positive electrode film layer arranged on at least one surface of the positive electrode current collector, and the positive electrode film layer includes a positive electrode active material.
  • the positive electrode current collector has two surfaces opposite to each other in its thickness direction, and the positive electrode film layer is disposed on any one or both of the two opposite surfaces of the positive electrode current collector.
  • the positive electrode current collector may be a metal foil or a composite current collector.
  • aluminum foil may be used as the metal foil.
  • the composite current collector may include a polymer material base and a metal layer formed on at least one surface of the polymer material base.
  • the composite current collector may be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).
  • PP polypropylene
  • PET polyethylene terephthalate
  • PBT polybutylene terephthalate
  • PS polystyrene
  • PE polyethylene
  • the positive electrode active material may be a positive electrode active material for lithium ion batteries known in the art.
  • the positive electrode active material may include at least one of the following materials: an olivine-structured lithium-containing phosphate, a lithium transition metal oxide, and their respective modified compounds.
  • the present application is not limited to these Materials, other conventional materials that can be used as positive electrode active materials for lithium ion batteries can also be used. These positive electrode active materials can be used alone or in combination of two or more.
  • lithium transition metal oxides may include, but are not limited to, lithium cobalt oxide (such as LiCoO2 ), lithium nickel oxide (such as LiNiO2 ), lithium manganese oxide (such as LiMnO2 , LiMn2O4 ), lithium nickel cobalt oxide , lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide (such as LiNi1 / 3Co1/ 3Mn1 / 3O2 (also referred to as NCM333), LiNi0.5Co0.2Mn0.3O2 (also referred to as NCM523), LiNi0.5Co0.25Mn0.25O2 (also referred to as NCM211), LiNi0.6Co0.2Mn0.2O2 (also referred to as NCM622 ), LiNi0.8Co0.1Mn0.1O2 (also referred to as NCM811), lithium nickel cobalt aluminum oxide (such as LiNi0.85Co0.2Mn0.3O2 ) , LiNi0.5Co
  • lithium-containing phosphates with an olivine structure may include, but are not limited to, at least one of lithium iron phosphate (such as LiFePO 4 (also referred to as LFP)), a composite material of lithium iron phosphate and carbon, lithium manganese phosphate (such as LiMnPO 4 ), a composite material of lithium manganese phosphate and carbon, lithium iron manganese phosphate, and a composite material of lithium iron manganese phosphate and carbon.
  • lithium iron phosphate such as LiFePO 4 (also referred to as LFP)
  • LiMnPO 4 lithium manganese phosphate
  • LiMnPO 4 lithium manganese phosphate
  • LiMnPO 4 lithium manganese phosphate and carbon
  • the positive electrode film layer may also optionally include a binder.
  • the binder may include at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorine-containing acrylate resin.
  • PVDF polyvinylidene fluoride
  • PTFE polytetrafluoroethylene
  • PTFE polytetrafluoroethylene
  • vinylidene fluoride-tetrafluoroethylene-propylene terpolymer vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer
  • the positive electrode film layer may further include a conductive agent, for example, the conductive agent may include at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene and carbon nanofibers.
  • the conductive agent may include at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene and carbon nanofibers.
  • the positive electrode sheet can be prepared in the following manner: the components for preparing the positive electrode sheet, such as the positive electrode active material, the conductive agent, the binder and any other components are dispersed in a solvent (such as N-methylpyrrolidone) to form a positive electrode slurry; the positive electrode slurry is coated on the positive electrode collector, and after drying, cold pressing and other processes, the positive electrode sheet can be obtained.
  • a solvent such as N-methylpyrrolidone
  • the negative electrode sheet includes a negative electrode current collector and a negative electrode film layer disposed on at least one surface of the negative electrode current collector, wherein the negative electrode film layer includes a negative electrode active material.
  • the negative electrode current collector has two surfaces opposite to each other in its thickness direction, and the negative electrode film layer is disposed on any one or both of the two opposite surfaces of the negative electrode current collector.
  • the negative electrode current collector may be a metal foil or a composite current collector.
  • the metal foil copper foil can be used.
  • the composite current collector may include a polymer material base layer and a metal layer formed on at least one surface of the polymer material substrate.
  • the composite current collector may be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).
  • PP polypropylene
  • PET polyethylene terephthalate
  • PBT polybutylene terephthalate
  • PS polystyrene
  • PE polyethylene
  • the negative electrode active material may adopt the negative electrode active material for the battery known in the art.
  • the negative electrode active material may include at least one of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, lithium titanate, etc.
  • the silicon-based material may include at least one of elemental silicon, silicon oxide compounds, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys.
  • the tin-based material may include at least one of elemental tin, tin oxide compounds, and tin alloys.
  • the present application is not limited to these materials, and other traditional materials that can be used as negative electrode active materials for batteries may also be used. These negative electrode active materials may be used alone or in combination of two or more.
  • the negative electrode film layer may further optionally include a binder.
  • the binder may include at least one of styrene-butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA) and carboxymethyl chitosan (CMCS).
  • the negative electrode film layer may further include a conductive agent, which may include at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.
  • a conductive agent which may include at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.
  • the negative electrode film layer may optionally include other additives, such as a thickener (eg, sodium carboxymethyl cellulose (CMC-Na)).
  • a thickener eg, sodium carboxymethyl cellulose (CMC-Na)
  • the negative electrode sheet can be prepared in the following manner: the components for preparing the negative electrode sheet, such as the negative electrode active material, the conductive agent, the binder and any other components are dispersed in a solvent (such as deionized water) to form a negative electrode slurry; the negative electrode slurry is coated on the negative electrode collector, and after drying, cold pressing and other processes, the negative electrode sheet can be obtained.
  • a solvent such as deionized water
  • the battery cell further includes a separator.
  • the present application has no particular limitation on the type of separator, and any known porous separator with good chemical stability and mechanical stability can be selected.
  • the material of the isolation membrane may include at least one of glass fiber, non-woven fabric, polyethylene, polypropylene and polyvinylidene fluoride.
  • the isolation membrane may be a single-layer film or a multi-layer composite film, without particular limitation.
  • the materials of each layer may be the same or different, without particular limitation.
  • FIG1 is a battery cell 20 of a square structure as an example.
  • the present application also provides an electric device, which includes at least one of the battery cells, battery modules or batteries provided in the present application.
  • the battery cells, battery modules or batteries can be used as the power source of the electric device, and can also be used as the energy storage unit of the electric device.
  • the electric device may include mobile devices (such as mobile phones, laptops, etc.), electric vehicles (such as pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc., but are not limited thereto.
  • a battery cell, a battery module or a battery can be selected according to its usage requirements.
  • FIG4 is an example of an electric device.
  • the electric device is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle, etc.
  • batteries or battery modules may be used.
  • a device may be a mobile phone, a tablet computer, a notebook computer, etc. Such a device is usually required to be light and thin, and a battery cell may be used as a power source.
  • isolation film A conventional polypropylene film was used as the isolation film.
  • the first additive is compound 1.
  • an electrolyte 1 containing compound 1 is prepared, and the mass content of compound 1 in electrolyte 1 is 1%.
  • a lithium ion battery 1 containing electrolyte 1 is prepared, corresponding to Example 1.
  • the first additive is compound 2.
  • an electrolyte 2 containing compound 2 is prepared, and the mass content of compound 2 in the electrolyte 2 is 1%.
  • a lithium-ion battery 2 containing electrolyte 2 is prepared, corresponding to Example 2.
  • the first additive is compound 3.
  • an electrolyte 3 containing compound 3 is prepared, and the mass content of compound 3 in the electrolyte 3 is 1%.
  • a lithium-ion battery 3 containing electrolyte 3 is prepared, corresponding to Example 3.
  • the first additive is compound 4.
  • an electrolyte 4 containing compound 4 is prepared.
  • the mass content of compound 4 in the electrolyte 4 is 1%.
  • the above lithium ion battery assembly method, Method to prepare a lithium ion battery 4 containing an electrolyte 4, corresponding to Example 4.
  • the first additive is compound 5.
  • an electrolyte 5 containing compound 5 is prepared, and the mass content of compound 5 in the electrolyte 5 is 1%.
  • a lithium-ion battery 5 containing electrolyte 5 is prepared, corresponding to Example 5.
  • the first additive is compound 6.
  • an electrolyte 6 containing compound 6 is prepared, and the mass content of compound 6 in the electrolyte 6 is 1%.
  • a lithium-ion battery 6 containing electrolyte 6 is prepared, corresponding to Example 6.
  • Examples 7 and 8 and Example 4 The difference between Examples 7 and 8 and Example 4 is that the mass of compound 4 added to the electrolyte is different.
  • the mass content of compound 4 in the prepared electrolyte 7 and electrolyte 8 is 10% and 0.0001%, respectively.
  • lithium ion battery 7 containing electrolyte 7 and lithium ion battery 8 containing electrolyte 8 are prepared, corresponding to Examples 7 and 8.
  • Example 9 The difference between Example 9 and Example 4 is that on the basis of Example 4, SO 2 with a mass content of 20 ppm is further added to obtain a lithium ion battery 9 corresponding to Example 9.
  • Example 10 is different from Example 9 in that, on the basis of Example 9, 5 ppm of 2,6-di-tert-butyl-p-cresol is added as an inhibitor to prepare a lithium ion battery 10 corresponding to Example 10.
  • Example 11 is relative to Example 10, except that on the basis of Example 10, 1% by weight of difluoroethylene carbonate (DFEC) is added to obtain a lithium ion battery 11, corresponding to Example 11.
  • DFEC difluoroethylene carbonate
  • Example 12 The difference between Example 12 and Example 4 is that on the basis of Example 4, SO 2 with a mass content of 900 ppm is further added to obtain a lithium ion battery 12 corresponding to Example 12.
  • the first additive is compound 7.
  • an electrolyte 14 containing compound 7 is prepared, and the mass content of compound 7 in the electrolyte 14 is 1%.
  • a lithium-ion battery 14 containing electrolyte 14 is prepared, corresponding to Example 14.
  • the first additive is compound 8.
  • an electrolyte 15 containing compound 8 is prepared, and the mass content of compound 8 in the electrolyte 15 is 1%.
  • a lithium-ion battery 15 containing electrolyte 15 is prepared, corresponding to Example 15.
  • the first additive is compound 9.
  • an electrolyte 16 containing compound 9 is prepared, and the mass content of compound 9 in the electrolyte 16 is 1%.
  • a lithium-ion battery 16 containing electrolyte 16 is prepared, corresponding to Example 16.
  • the first additive is compound 10.
  • an electrolyte 17 containing compound 17 is prepared, and the mass content of compound 10 in the electrolyte 17 is 1%.
  • a lithium-ion battery 17 containing electrolyte 17 is prepared, corresponding to Example 17.
  • the first additive is compound 11.
  • an electrolyte 18 containing compound 11 is prepared, and the mass content of compound 11 in the electrolyte 18 is 1%.
  • a lithium-ion battery 18 containing electrolyte 18 is prepared, corresponding to Example 18.
  • Embodiments 19 and 20 are different from Embodiment 16, except that the mass of compound 9 added to the electrolyte is different.
  • the mass content of compound 9 in the prepared electrolyte 19 and electrolyte 20 is 10% and 0.0001%, respectively.
  • lithium ion battery 19 containing electrolyte 19 and lithium ion battery 20 containing electrolyte 20 are prepared, corresponding to Embodiments 19 and 20, respectively.
  • Example 21 is different from Example 16 in that, based on Example 16, a mass The amount of SO 2 was 20 ppm, and a lithium ion battery 21 was prepared, corresponding to Example 21.
  • Example 22 is different from Example 21 in that, on the basis of Example 21, 5 ppm of hydroquinone is added as an inhibitor to obtain a lithium ion battery 22, corresponding to Example 22.
  • Example 23 is different from Example 22 in that, on the basis of Example 22, 1% by mass of diethyl sulfate (DTD) is added to obtain a lithium-ion battery 23, corresponding to Example 23.
  • DTD diethyl sulfate
  • Example 24 The difference between Example 24 and Example 16 is that on the basis of Example 16, CO 2 with a mass content of 20 ppm is further added to obtain a lithium ion battery 24 corresponding to Example 24.
  • Example 25 The difference between Example 25 and Example 16 is that on the basis of Example 16, SO 2 with a mass content of 900 ppm is further added to obtain a lithium ion battery 25 corresponding to Example 25.
  • Example 26 is different from Example 22, except that in Example 26, 30 ppm of hydroquinone is added as an inhibitor to prepare a lithium ion battery 26, corresponding to Example 26.
  • the first additive is VC.
  • an electrolyte 1' containing VC is prepared, and the mass content of VC in the electrolyte 1' is 1%.
  • a lithium ion battery 1' containing the electrolyte 1' is prepared, corresponding to Example 1.
  • the first additive is DTD.
  • an electrolyte 2' containing DTD is prepared, and the mass content of DTD in the electrolyte 2' is 1%.
  • a lithium-ion battery 2' containing the electrolyte 2' is prepared, corresponding to Example 2.
  • the lithium-ion battery is charged to 4.5V at 1C constant current, then charged to less than 0.05C at 4.5V constant voltage, and then discharged to 2.8V at 1C constant current. This is a charge and discharge process. Repeat the charge and discharge process and calculate the number of cycles at which the lithium-ion capacity retention rate is 80%.
  • the capacity retention rate (%) of a lithium-ion battery after n cycles (discharge capacity at the nth cycle/discharge capacity at the first cycle) ⁇ 100%.
  • Example 10 From the comparison of the results of Example 10 and Example 11, it can be seen that when DFEC is added to the electrolyte, DFEC forms monomer active free radicals under the electrochemical reaction, thereby improving the reaction conversion rate of the first additive copolymerization to form a copolymer, so that the molecular weight of the initially formed copolymer interface film is larger and denser, which can improve the cycle performance and service life of the lithium-ion battery.
  • Example 22 From the comparison of the results of Example 22 and Example 23, it can be seen that when DTD is added to the electrolyte, DTD forms monomer active free radicals under electrochemical reaction, thereby improving the reaction conversion rate of the first additive copolymerization to form a copolymer, so that the molecular weight of the initially formed copolymer interface film is larger and denser, which can improve the cycle performance and service life of the lithium-ion battery.

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Abstract

本申请实施例提供一种电解液、含有其的电池和用电装置。该电解液包括：第一添加剂，该第一添加剂包括至少含有式(I)和式(II)所示的基团的化合物、至少含有式(I)和式(Ш)所示的基团的化合物中的至少一种，含有该电解液的电池的循环性能和存储寿命都有提升。

Description

电解液、含有其的电池和用电装置 技术领域
本申请涉及电池技术领域，特别是涉及一种电解液、含有其的电池和用电装置。
背景技术
近年来，二次电池由于其较高的能量密度以及可循环性能，被广泛应用于水力、火力、风力和太阳能电站等储能电源系统，以及电动工具、电动自行车、电动摩托车、电动汽车、军事装备、航空航天等多个领域。随着二次电池取得的极大发展以及广泛应用，对其循环性能、存储寿命等性能也提出了更高的要求。
因此，如何提升二次电池的循环性能和存储寿命是一项丞待解决的技术问题。
发明内容
本申请实施例提供了一种电解液、含有其的电池和用电装置，含有该电解液的电池循环性能和存储寿命都有提升。
第一方面，提供了一种电解液，包括：第一添加剂，所述第一添加剂包括至少含有式(I)和式(II)所示的基团的化合物、至少含有式(I)和式(Ш)所示的基团的化合物中的至少一种：
其中，R1、R3和R4各自独立地包括饱和或不饱和的烃基中的至少一种，R2包括F、OLi、OCH2CF3、OCH3、OCH2CH2＝CH2、OCH2CH2CH2＝CH2、OSi(OCH3)3、OSi(OCH2CH2＝CH2)3或OSi(CH2＝CH2)3，X1和X2包括O或CH2且X1和X2不同时为CH2。
本申请的实施例中，电解液包括第一添加剂，该第一添加剂包括至少含有式(I)和式(II)所示的基团的化合物、至少含有式(I)和式(Ш)所示的基团的化合物中的至少一种。也就是第一添加剂包括同时包含环状磷酸酯和环状碳酸酯结构的化合物、同时包含环状磷酸酯以及环状硫酸酯和/或环状磺酸酯结构的化合物中的至少一种。该第一添加剂在电极界面发生共聚反应，参与电池化成阶段的成膜，形成的共聚物兼具了聚碳酸酯聚合物和聚磷酸酯聚合物或者是聚磷酸酯以及聚硫酸酯和/或聚磺酸酯的优点，共聚物的结晶度降低，形成的界面膜的韧性也得到提高，界面膜的稳定性有所提升，从而提升了电池的存储寿命。另外，同时包含环状碳酸酯和环状磷酸酯结构的化合物、同时包含环状磷酸酯以及环状硫酸酯和/或环状磺酸酯结构的化合物分子结构较大，位阻较大，溶剂化能力弱，因此在电极极片界面反应活性低，在电解液中消耗速率慢，能为电池持续提供成膜物质，用于修复电极极片和电解液之间的界面膜，从而降低电池循环中后期的寿命衰减速度，提升电池的循环稳定性和使用寿命。
在一种可能的实施方式中，所述第一添加剂在所述电解液中的质量含量为0.0001％～10％，可选地，所述第一添加剂在所述电解液中的质量含量为0.01％～5％。
第一添加剂在电解液中的含量过少，则不能形成足够的共聚物参与成膜，影响界面膜的稳定性，导致电极极片和电解液间的界面不稳定；第一添加剂在电解液中的含量过高，会使电解液的粘度太大，影响电解液对电极极片的浸润，影响电池的充放电性能。
在一种可能的实施方式中，所述第一添加剂包括式(IV)、式(V)、式(VI)、式(VII)所示的化合物中的至少一种：

其中，R5和R6各自独立地包括H、卤原子、取代或未取代的烃基、含有不饱和双键或三键的基团中的至少一种，R7和R8各自独立地包括碳原子数为1-6的饱和或不饱和的烃基、单键中的至少一种，x的取值为1-5中任一自然数，y的取值为0-5中任一自然数。
本申请实施例中，通过在式(IV)、式(V)、式(VI)、式(VII)的化合物中引入卤原子，能够提高化合物中的无机组分含量，以提高界面膜的绝缘性；在化合物中引入烃基，可以提高化合物的稳定性；在化合物的端基中引入不饱和双键或三键，使得第一添加剂具有多官能团结构，在成膜阶段更易形成交联网状结构，能更好的包裹电极材料颗粒结构，同时能抑制电极材料膨胀，进一步改善循环存储性能。
在一种可能的实施方式中，R5和R6各自独立地包括H、F、碳原子数为1-3的直链烷基或支链烷基、碳原子数为1-3的直链全氟取代烷基或支链全氟取代烷基、含有不饱和双键的碳原子数为1-3的基团中的至少一种。
本申请实施例中，通过调整引入式(IV)、式(V)、式(VI)、式(VII)化合物的基团的碳原子数，优化式(IV)、式(V)、式(VI)、式(VII)化合物的结构，使得第一添加剂在电解液中具有适宜的溶解度和粘度，在电解液中能够更好参与成膜，提升电极极 片和电解液之间的界面膜的稳定性。
在一种可能的实施方式中，R7和R8各自独立地包括碳原子数为1-3的饱和或不饱和的烃基中的至少一种。
本申请实施例中，若多个酯类基团之间的烃基结构碳原子数过多，烃基结构过长，会影响第一添加剂形成的电极界面膜的致密性，通过调整R7和R8中的碳原子数，使多个酯类基团之间的烃基结构长度适宜，以形成结构紧密的电极界面膜。
在一种可能的实施方式中，所述第一添加剂包括以下物质中的至少一种：




在一种可能的实施方式中，所述电解液还包括第二添加剂，所述第二添加剂包括碳酸酯、磺酸酯、硫酸酯、磷酸酯中的至少一种。
在电池化成阶段，碳酸酯、磺酸酯、硫酸酯、磷酸酯在电化学反应下形成单体活性自由基，进而提高第一添加剂共聚形成共聚物的反应转化率，使得初始形成的共聚物界面膜分子量更大，更为致密，进一步改善初始成膜质量。
在一种可能的实施方式中，所述第二添加剂包括碳酸亚乙烯酯、双氟代碳酸乙烯酯、氟代碳酸乙烯酯、碳酸乙烯亚乙酯、丙磺酸内酯、丙烯基-1,3-磺酸内酯、硫酸乙烯酯、双硫酸乙烯酯、三(2,2,2-三氟乙基)磷酸酯、三烯丙基磷酸酯、二氟磷酸 锂中的至少一种。
在一种可能的实施方式中，所述电解液还包括第三添加剂，所述第三添加剂包括SO2、CO2中的至少一种。
本申请实施例中，在电解液中添加SO2、CO2中的至少一种，SO2、CO2可以改变第一添加剂在化成阶段的断裂成键形式，抑制第一添加剂在化成阶段形成SO2、CO2，而是更多的形成含有碳酸盐、硫酸盐以及聚碳酸酯-聚磷酸酯和/或聚硫酸酯/聚磺酸酯-聚磷酸酯的无机-有机致密界面膜，也就是共聚物中含有更多的硫酸盐和碳酸盐结构，使得界面膜更致密，更好阻止电解液中其他分子的共嵌入，避免其他分子共嵌入对电极材料的破坏，从而提高电池的循环稳定性和使用寿命。
在一种可能的实施方式中，所述第三添加剂在所述电解液中的质量含量为10～1000ppm。
SO2、CO2的含量太少，不能有效抑制第一添加剂在化成阶段形成SO2、CO2；SO2、CO2的含量太多，会导致电解液中存在过多的硫酸根离子、碳酸根离子，可能会跟电极材料产生的金属离子结合，使电解液中游离的金属离子减少，导致电池的容量衰减。
在一种可能的实施方式中，所述电解液还包括阻聚剂，可选地，所述阻聚剂包括对苯二酚、2,6-二叔丁基对甲苯酚中的至少一种。
在电解液中加入对苯二酚、2,6-二叔丁基对甲苯酚作为阻聚剂，以在电池的运输过程中，降低电解液中的物质在充分接触的情况下发生化学反应的风险，从而降低电解液的组成成分被破坏的风险。
在一种可能的实施方式中，所述阻聚剂在所述电解液中的质量含量小于20ppm，可选地，所述阻聚剂在所述电解液中的质量含量小于10ppm。
阻聚剂的电解液中的含量不易过高，否则会抑制第一添加剂的共聚反应，影响电池在化成阶段的成膜，不能在电极极片和电解液之间形成稳定的界面膜。控制阻聚剂的含量，提升电池在化成阶段的成膜质量，从而提升电池的使用性能和使用寿命。
在一种可能的实施方式中，所述电解液还包括溶剂，所述溶剂在25℃时的 相对介电常数大于2且粘度小于2mPa.s。
电解液中的溶剂的相对介电常数太小，或者是粘度太大，都会导致添加剂在溶剂中难以溶解。
在一种可能的实施方式中，所述溶剂包括碳酸酯、羧酸酯、醚、砜、氟代碳酸酯、氟代羧酸酯、氟代醚、氟代砜中的至少一种。
在一种可能的实施方式中，所述电解液还包括金属盐，所述金属盐包括六氟磷酸锂、四氟硼酸锂、高氯酸锂、六氟砷酸锂、双氟磺酰亚胺锂、双三氟甲磺酰亚胺锂、三氟甲磺酸锂、二氟草酸硼酸锂、二草酸硼酸锂、二氟磷酸锂、二氟二草酸磷酸锂、四氟草酸磷酸锂中的至少一种，可选地，所述金属盐包括六氟磷酸锂、双氟磺酰亚胺锂中的至少一种。
在一种可能的实施方式中，所述电解液的酸度值小于800ppm。
电解液的酸度值过大，容易使第一添加剂不稳定而降解，从而难以形成共聚物，影响成膜质量。
第二方面，提供了一种电池，包括：上述第一方面或第一方面的任意可能的实现方式中的电解液。
第三方面，提供了一种用电设备，包括：上述第二方面或第二方面的任意可能的实现方式中的电池，所述电池用于提供电能。
在本申请的实施例中，电解液包括第一添加剂，该第一添加剂包括至少含有式(I)和式(II)所示的基团的化合物、至少含有式(I)和式(Ш)所示的基团的化合物中的至少一种。也就是第一添加剂包括同时包含环状磷酸酯和环状碳酸酯结构的化合物、同时包含环状磷酸酯以及环状硫酸酯和/或环状磺酸酯结构的化合物中的至少一种。该第一添加剂在电极界面发生共聚反应，参与电池化成阶段的成膜，形成的共聚物兼具了聚碳酸酯聚合物和聚磷酸酯聚合物或者是聚磷酸酯以及聚硫酸酯和/或聚磺酸酯的优点，共聚物的结晶度降低，形成的界面膜的韧性也得到提高，界面膜的稳定性有所提升，从而提升了电池的存储寿命。另外，同时包含环状碳酸酯和环状磷酸酯结构的化合物、同时包含环状磷酸酯以及环状硫酸酯和/或环状磺酸酯结构的化合物分子结构较大，位阻较大，溶剂化能力弱，因此在电极极片界面反应活性低，在电解液中消耗速率慢，能为电池持续提供成膜物质，用于修复电极极片和电解液之间的界面膜，从而 降低电池循环中后期的寿命衰减速度，提升电池的循环稳定性和使用寿命。
附图说明
为了更清楚地说明本申请实施例的技术方案，下面将对本申请实施例中所需要使用的附图作简单地介绍，显而易见地，下面所描述的附图仅仅是本申请的一些实施例，对于本领域普通技术人员来讲，在不付出创造性劳动的前提下，还可以根据附图获得其他的附图。
图1是本申请一实施例公开的一种电池单体的示意图；
图2是本申请一实施例公开的一种电池单体的分解结构示意图；
图3是本申请一实施例公开的一种电池的分解结构示意图；
图4是本申请一实施例公开的一种用电装置的示意图。
在附图中，附图并未按照实际的比例绘制。
具体实施方式中的附图标号如下：
电池10，箱体11，电池单体20，壳体21，电极组件22，盖板23。
具体实施方式
以下，适当地参照附图详细说明具体公开了本申请的电解液、含有其的电池单体、电池和用电装置的实施方式。但是会有省略不必要的详细说明的情况。例如，有省略对已众所周知的事项的详细说明、实际相同结构的重复说明的情况。这是为了避免以下的说明不必要地变得冗长，便于本领域技术人员的理解。此外，附图及以下说明是为了本领域技术人员充分理解本申请而提供的，并不旨在限定权利要求书所记载的主题。
在本申请的描述中，需要说明的是，除非另有说明，“多个”的含义是两个以上；术语“上”、“下”、“左”、“右”、“内”、“外”等指示的方位或位置关系仅是为了便于描述本申请和简化描述，而不是指示或暗示所指的装置或元件必须具有特定的方位、以特定的方位构造和操作，因此不能理解为对本申请的限制。此外，术语“第一”、“第二”、“第三”等仅用于描述目的，而不能理解为指示或暗 示相对重要性。
本申请所公开的“范围”以下限和上限的形式来限定，给定范围是通过选定一个下限和一个上限进行限定的，选定的下限和上限限定了特别范围的边界。这种方式进行限定的范围可以是包括端值或不包括端值的，并且可以进行任意地组合，即任何下限可以与任何上限组合形成一个范围。例如，如果针对特定参数列出了60-120和80-110的范围，理解为60-110和80-120的范围也是预料到的。此外，如果列出的最小范围值1和2，和如果列出了最大范围值3，4和5，则下面的范围可全部预料到：1-3、1-4、1-5、2-3、2-4和2-5。在本申请中，除非有其他说明，数值范围“a-b”表示a到b之间的任意实数组合的缩略表示，其中a和b都是实数。例如数值范围“0-5”表示本文中已经全部列出了“0-5”之间的全部实数，“0-5”只是这些数值组合的缩略表示。另外，当表述某个参数为≥2的整数，则相当于公开了该参数为例如整数2、3、4、5、6、7、8、9、10、11、12等。
如果没有特别的说明，本申请的所有步骤可以顺序进行，也可以随机进行，优选是顺序进行的。例如，所述方法包括步骤(a)和(b)，表示所述方法可包括顺序进行的步骤(a)和(b)，也可以包括顺序进行的步骤(b)和(a)。例如，所述提到所述方法还可包括步骤(c)，表示步骤(c)可以任意顺序加入到所述方法，例如，所述方法可以包括步骤(a)、(b)和(c)，也可包括步骤(a)、(c)和(b)，也可以包括步骤(c)、(a)和(b)等。
如果没有特别的说明，本申请所提到的“包括”和“包含”表示开放式，也可以是封闭式。例如，所述“包括”和“包含”可以表示还可以包括或包含没有列出的其他组分，也可以仅包括或包含列出的组分。
如果没有特别的说明，在本申请中，术语“或”是包括性的。举例来说，短语“A或B”表示“A，B，或A和B两者”。更具体地，以下任一条件均满足条件“A或B”：A为真(或存在)并且B为假(或不存在)；A为假(或不存在)而B为真(或存在)；或A和B都为真(或存在)。
如果没有特别的说明，本申请的所有实施方式以及可选实施方式可以相互组合形成新的技术方案。
如果没有特别的说明，本申请的所有技术特征以及可选技术特征可以相互组合形成新的技术方案。
如果没有特别的说明，以下术语具有以下含义。任何未定义的术语具有它们在技术上公认的含义。
“烷基”指的是具有一个或多个碳原子的单价饱和烃基，可选地，碳原子数为1-18。举例来说，烷基包括直链烷基和支链烷基，例如甲基(CH3-)，乙基(CH3CH2-)，正丙基(CH3CH2CH2-)，异丙基((CH3)2CH-)，正丁基(CH3CH2CH2CH2-)，异丁基((CH3)2CHCH2-)，仲丁基((CH3)(CH3CH2)CH-)，叔丁基((CH3)3C-)，正戊基(CH3CH2CH2CH2CH2-)，新戊基((CH3)3CCH2-)等。
“全氟取代烷基”指的是将烷基中的碳氢键的氢原子全部用氟原子取代。例如全氟取代甲基(CF3-)，全氟取代乙基(CF3CF2-)，全氟取代正丙基(CF3CF2CF2-)，全氟取代异丁基((CF3)2CFCF2-)等。
“不饱和双键”指的是两个原子共用两对电子对成键。例如碳碳双键(C＝C)，碳氧双键(C＝O)等。
通常情况下，二次电池包括正极极片、负极极片、电解液和隔离膜。在电池的充放电过程中，活性离子在正极极片和负极极片之间往返嵌入和脱出。其中，电解液中的电解质在正极极片和负极极片之间起到传导离子的作用。隔离膜设置于正极极片和负极极片之间，在防止正负极短路的同时使得离子能够从中通过，使得二次电池电化学反应正常进行。
二次电池可以包括锂离子电池、钠离子电池、镁离子电池等。本申请以锂离子电池为示例，锂离子电池是一种典型的二次电池，由于其依靠锂离子在正负极之间脱嵌的化学反应进行充放电，锂离子电池又被称为摇椅式电池。锂离子电池的充电过程中，锂离子从正极脱出，移动并嵌入到负极；而放电过程中，锂离子从负极脱出，移动并嵌入正极。
近年来，二次电池得到了极大的发展，被广泛应用于电动工具、电子产品、电动汽车、航空航天等多个领域的同时，也对二次电池的体积容量、能量密度以及循环性能等提出了更高的要求。
二次电池在首次充电过程中，电解液中的成膜添加剂会在电极极片表面还原形成一层固体电解质界面(Solid electrolyte interphase，SEI)膜，SEI膜能够阻止电解液中的非水有机溶剂进一步分解，并在随后的充放电循环中形成离子通道。然而， 随着充放电的进行，电解液与电极极片之间的SEI膜的稳定性会变差，逐渐破裂再重生，造成电解液不断被消耗，影响二次电池的循环稳定性和使用寿命。
鉴于此，本申请提供了一种电解液，电解液包括第一添加剂，该第一添加剂包括至少含有式(I)和式(II)所示的基团的化合物、至少含有式(I)和式(Ш)所示的基团的化合物中的至少一种。也就是第一添加剂包括同时包含环状磷酸酯和环状碳酸酯结构的化合物、同时包含环状磷酸酯以及环状硫酸酯和/或环状磺酸酯结构的化合物中的至少一种。该第一添加剂在电极界面发生共聚反应，参与电池化成阶段的成膜，形成的共聚物兼具了聚碳酸酯聚合物和聚磷酸酯聚合物或者是聚磷酸酯以及聚硫酸酯和/或聚磺酸酯的优点，共聚物的结晶度降低，形成的界面膜的韧性也得到提高，界面膜的稳定性有所提升，从而提升了电池的存储寿命。另外，同时包含环状碳酸酯和环状磷酸酯结构的化合物、同时包含环状磷酸酯以及环状硫酸酯和/或环状磺酸酯结构的化合物分子结构较大，位阻较大，溶剂化能力弱，因此在电极极片界面反应活性低，在电解液中消耗速率慢，能为电池持续提供成膜物质，用于修复电极极片和电解液之间的界面膜，从而降低电池循环中后期的寿命衰减速度，提升电池的循环稳定性和使用寿命。
以下，具体介绍本申请的多个实施例。
[电解液]
电解液在正极极片和负极极片之间起到传导离子的作用。本申请提供的电解液包括第一添加剂，具体地，该第一添加剂包括至少含有式(I)和式(II)所示的基团的化合物、至少含有式(I)和式(Ш)所示的基团的化合物中的至少一种：
其中，R1、R3和R4各自独立地包括饱和或不饱和的烃基中的至少一种，R2包括F、OLi、OCH2CF3、OCH3、OCH2CH2＝CH2、OCH2CH2CH2＝CH2、OSi(OCH3)3、OSi(OCH2CH2＝CH2)3或OSi(CH2＝CH2)3，X1和X2包括O或CH2且X1和X2不同时为CH2。
具体来说，第一添加剂包括同时包含环状碳酸酯和环状磷酸酯结构的化合物、同时包含环状磷酸酯以及环状硫酸酯和/或环状磺酸酯结构的化合物中的至少一种。环状碳酸酯介电常数高、离子电导率高，能够在电极表面形成稳定的界面膜，环状磷酸酯添加在电解液中可以使得电解液具有良好的稳定性和较高的电导率，同时增加电池的安全性和阻燃性。在电解液中，同时包含环状碳酸酯和环状磷酸酯结构的化合物发生共聚反应，形成的共聚物兼具了聚碳酸酯聚合物和聚磷酸酯聚合物的优点。环状硫酸酯添加在电解液中可以抑制电池初始容量的下降，增大初始放电容量，减少高温放置后的电池膨胀，提高电池的充放电性能及循环性能。环状磺酸酯添加在电解液中，能够在电极表面形成稳定的界面膜。在电解液中，同时包含环状磷酸酯以及环状硫酸酯和/或环状磺酸酯结构的化合物发生共聚反应，形成的共聚物兼具了聚磷酸酯聚合物以及聚硫酸酯聚合物和/或聚磺酸酯聚合物的优点。
因此，本申请实施例提供的电解液，包括第一添加剂，该第一添加剂包括至少含有式(I)和式(II)所示的基团的化合物、至少含有式(I)和式(Ш)所示的基团的化合物中的至少一种。也就是第一添加剂包括同时包含环状磷酸酯和环状碳酸酯结构的化合物、同时包含环状磷酸酯以及环状硫酸酯和/或环状磺酸酯结构的化合物中的至少一种。该第一添加剂在电极界面发生共聚反应，参与电池化成阶段的成膜，形成的共聚物兼具了聚碳酸酯聚合物和聚磷酸酯聚合物或者是聚磷酸酯以及聚硫酸酯和/或聚磺酸酯的优点，共聚物的结晶度降低，形成的界面膜的韧性也得到提高，界面膜的稳定性有所提升，从而提升了电池的存储寿命。另外，同时包含环状碳酸酯和环状磷酸酯结构的化合物、同时包含环状磷酸酯以及环状硫酸酯和/或环状磺酸酯结构的化合物分子结构较大，位阻较大，溶剂化能力弱，因此在电极极片界面反应活性低，在电解液中消耗速率慢，能为电池持续提供成膜物质，用于修复电极极片和电解液之间的界面膜，从而降低电池循环中后期的寿命衰减速度，提升电池的循环稳定性和使用寿命。
可选地，在一些实施例中，第一添加剂在电解液中的质量含量为0.0001％～10％，可选地，第一添加剂在电解液中的质量含量为0.01％～5％。
具体地，第一添加剂在电解液中的质量含量可以为0.0001％、0.0005％、0.001％、0.0015％、0.002％、0.0025％、0.003％、0.0035％、0.004％、0.0045％、0.005％、0.0055％、0.006％、0.0065％、0.007％、0.0075％、0.008％、0.0085％、0.009％、0.0095％、0.01％、0.02％、0.03％、0.04％、0.05％、0.06％、0.07％、0.08％、0.09％、 0.1％、0.2％、0.3％、0.4％、0.5％、0.6％、0.7％、0.8％、0.9％、1％、2％、3％、4％、5％、6％、7％、8％、9％、10％，或者其数值在上述任意两个数值组合所获得的范围之内。
可选地，在一些实施例中，第一添加剂包括式(IV)、式(V)、式(VI)、式(VII)所示的化合物中的至少一种：
其中，R5和R6各自独立地包括H、卤原子、取代或未取代的烃基、含有不饱和双键或三键的基团中的至少一种，R7和R8各自独立地包括碳原子数为1-6的饱和或不饱和的烃基、单键中的至少一种，x的取值为1-5中任一自然数，y的取值为0-5中任一自然数。
本申请实施例中，通过在式(IV)、式(V)、式(VI)、式(VII)的化合物中引入卤原子，能够提高化合物中的无机组分含量，以提高界面膜的绝缘性；在化合物中引 入烃基，可以提高化合物的稳定性；在化合物的端基中引入不饱和双键或三键，使得第一添加剂具有多官能团结构，在成膜阶段更易形成交联网状结构，能更好的包裹电极材料颗粒结构，同时能抑制电极材料膨胀，进一步改善循环存储性能。
可选地，x的取值可以为1、2，y的取值可以为0、1、2。比如，x＝1，y＝1；x＝2，y＝1；x＝2，y＝2；x＝1，y＝2，x＝2，y＝0。
可选地，在一些实施例中，R5和R6各自独立地包括H、F、碳原子数为1-3的直链烷基或支链烷基、碳原子数为1-3的直链全氟取代烷基或支链全氟取代烷基、含有不饱和双键的碳原子数为1-3的基团中的至少一种。
本申请实施例中，通过调整引入式(IV)、式(V)、式(VI)、式(VII)化合物的基团的碳原子数，优化式(IV)、式(V)、式(VI)、式(VII)化合物的结构，使得第一添加剂在电解液中具有适宜的溶解度和粘度，在电解液中能够更好参与成膜，提升电极极片和电解液之间的界面膜的稳定性。
可选地，在一些实施例中，R7和R8各自独立地包括碳原子数为1-3的饱和或不饱和的烃基中的至少一种。
本申请实施例中，若多个酯类基团之间的烃基结构碳原子数过多，烃基结构过长，会影响第一添加剂形成的电极界面膜的致密性，通过调整R7和R8中的碳原子数，使多个酯类基团之间的烃基结构长度适宜，以形成结构紧密的电极界面膜。
可选地，在一些实施例中，第一添加剂包括以下物质中的至少一种：





应理解，本申请实施例提供的第一添加剂包括的多种化合物仅作为示例，不应理解成对本申请化合物的限定。
本申请实施例中，选择卤素中电负性最强的氟原子引入式(I)所示的环状磷酸酯结构中，能够进一步提高含有该环状磷酸酯结构的化合物的稳定性和抗氧化性能。可选地，式(I)所示的环状磷酸酯结构中的R2为氟原子。
第一添加剂在电解液中的含量过少，则不能形成足够的共聚物参与成膜，影响界面膜的稳定性，导致电极极片和电解液间的界面不稳定；第一添加剂在电解液中的含量过高，会使电解液的粘度太大，影响电解液对电极极片的浸润，影响电池的充放电性能。
可选地，在一些实施例中，电解液还包括第二添加剂，第二添加剂包括碳酸酯、磺酸酯、硫酸酯、磷酸酯中的至少一种。
具体地，第二添加剂包括碳酸亚乙烯酯(VC)、双氟代碳酸乙烯酯(DFEC)、氟代碳酸乙烯酯(FEC)、碳酸乙烯亚乙酯(VEC)、丙磺酸内酯、丙烯基-1,3-磺酸内酯、硫酸乙烯酯、双硫酸乙烯酯、三(2,2,2-三氟乙基)磷酸酯、三烯丙基磷酸酯、二氟磷酸酯锂中的至少一种。
应理解，本申请实施例提供的用作第二添加剂的多种化合物仅作为示例，不应理解成对本申请第二添加剂的限定。
在电池化成阶段，碳酸酯、磺酸酯、硫酸酯、磷酸酯在电化学反应下形成单体活性自由基，进而提高第一添加剂共聚形成共聚物的反应转化率，使得初始形成 的共聚物界面膜分子量更大，更为致密，进一步改善初始成膜质量。
可选地，在一些实施例中，电解液还包括第三添加剂，第三添加剂包括SO2、CO2中的至少一种。
本申请实施例中，在电解液中添加SO2、CO2中的至少一种，SO2、CO2可以改变第一添加剂在化成阶段的断裂成键形式，抑制第一添加剂在化成阶段形成SO2、CO2，而是更多的形成含有硫酸盐、碳酸盐以及聚碳酸酯-聚磷酸酯和/或聚硫酸酯/聚磺酸酯-聚磷酸酯的无机-有机致密界面膜，也就是共聚物中含有更多的磷酸盐和碳酸盐结构，使得界面膜更致密，更好阻止电解液中其他分子的共嵌入，避免其他分子共嵌入对电极材料的破坏，从而提高电池的循环稳定性和使用寿命。
可选地，在一些实施例中，第三添加剂在所述电解液中的质量含量为10～1000ppm。
SO2、CO2的含量太少，不能有效抑制第一添加剂在化成阶段形成SO2、CO2；SO2、CO2的含量太多，会导致电解液中存在过多的硫酸根离子、碳酸根离子，可能会跟电极材料产生的金属离子结合，使电解液中游离的金属离子减少，导致电池的容量衰减。
可选地，在一些实施例中，电解液还包括阻聚剂，可选地，阻聚剂包括对苯二酚、2,6-二叔丁基对甲苯酚中的至少一种。
应理解，本申请实施例提供的用作阻聚剂的多种化合物仅作为示例，不应理解成对本申请阻聚剂的限定。
在电解液中加入对苯二酚、2,6-二叔丁基对甲苯酚作为阻聚剂，以在电池的运输过程中，降低电解液中的物质在充分接触的情况下发生化学反应的风险，从而降低电解液的组成成分被破坏的风险。
可选地，在一些实施例中，阻聚剂在电解液中的质量含量小于20ppm，可选地，阻聚剂在电解液中的质量含量小于10ppm。
可选地，阻聚剂在电解液中的质量含量可以为15ppm、10ppm、5ppm、4ppm、3ppm、2ppm、1ppm。
阻聚剂的电解液中的含量不易过高，否则会抑制第一添加剂的共聚反应， 影响电池在化成阶段的成膜，不能在电极极片和电解液之间形成稳定的界面膜。控制阻聚剂的含量，提升电池在化成阶段的成膜质量，从而提升电池的使用性能和使用寿命。
可选地，在一些实施例中，电解液还包括溶剂，溶剂在25℃时的相对介电常数大于2且粘度小于2mPa.s。
可选地，溶剂在25℃时的相对介电常数可以为3、4、5、6；溶剂在25℃时的粘度可以为1.5mPa.s、1mPa.s。
电解液中的溶剂的相对介电常数太小，或者是粘度太大，都会导致添加剂在溶剂中难以溶解。
可选地，在一些实施例中，溶剂包括碳酸酯、羧酸酯、醚、砜、氟代碳酸酯、氟代羧酸酯、氟代醚、氟代砜中的至少一种。
电解液的溶剂通常为有机溶剂，比如，碳酸酯、羧酸酯、醚、砜等，上述有机溶剂可以改善电解液对电极极片的浸润性，且具有高的介电常数，降低电极极片嵌入活性离子的阻抗，提高电导率，提高电池的循环性能。
可选地，在一些实施例中，电解液还包括金属盐。
以锂离子电池为例，锂离子电池的电解液中包括锂盐。具体地，锂盐包括六氟磷酸锂(LiPF6)、四氟硼酸锂(LiBF4)、高氯酸锂(LiClO4)、六氟砷酸锂(LiAsF6)、双氟磺酰亚胺锂(LiFSI)、双三氟甲磺酰亚胺锂(LiTFSI)、三氟甲磺酸锂(LiTFS)、二氟草酸硼酸锂(LiDFOB)、二草酸硼酸锂(LiBOB)、二氟磷酸锂(LiPO2F2)、二氟二草酸磷酸锂(LiDFOP)、四氟草酸磷酸锂(LiTFOP)中的至少一种，可选地，锂盐包括LiPF6、LiFSI中的至少一种。
二次电池可以包括锂离子电池、钠离子电池、镁离子电池等，相应地，金属盐可以为锂盐、钠盐、镁盐等。应理解，本申请实施例提供的多种金属盐仅作为示例，不应理解成对本申请金属盐的限定。
可选地，在一些实施例中，电解液的酸度值小于800ppm。
可选地，电解液的酸度值可以为700ppm、650ppm、600ppm、550ppm、500ppm。
具体来说，电解液的酸度值是指电解液中的氢氟酸(HF)的质量含量，可以使用三乙胺溶液标准溶液滴定电解液中游离的HF。
电解液的酸度值过大，容易使第一添加剂不稳定而降解，从而难以形成共聚物，影响成膜质量。
以下参照附图对本申请电池单体、电池和用电装置进行说明。
本申请实施例还提供一种电池单体。通常情况下，电池单体包括正极极片、负极极片、电解液和隔离膜。在电池充放电过程中，活性离子在正极极片和负极极片之间往返嵌入和脱出。电解液中的电解质在正极极片和负极极片之间起到传导离子的作用。隔离膜设置在正极极片和负极极片之间，主要起到防止正负极短路的作用，同时可以使离子通过。
应理解，本申请所述“嵌入”过程指活性离子由于电化学反应在正极活性材料或负极活性材料中嵌入的过程，本申请所述“脱出”、“脱嵌”过程指活性离子由于电化学反应在正极活性材料或负极活性材料中脱出的过程。
[正极极片]
正极极片包括正极集流体以及设置在正极集流体至少一个表面的正极膜层，正极膜层包括正极活性材料。
作为示例，正极集流体具有在其自身厚度方向相对的两个表面，正极膜层设置在正极集流体相对的两个表面的其中任意一者或两者上。
在一些实施方式中，正极集流体可采用金属箔片或复合集流体。例如，作为金属箔片，可采用铝箔。复合集流体可包括高分子材料基层和形成于高分子材料基层至少一个表面上的金属层。复合集流体可通过将金属材料(铝、铝合金、镍、镍合金、钛、钛合金、银及银合金等)形成在高分子材料基材(如聚丙烯(PP)、聚对苯二甲酸乙二醇酯(PET)、聚对苯二甲酸丁二醇酯(PBT)、聚苯乙烯(PS)、聚乙烯(PE)等的基材)上而形成。
在一些实施方式中，正极活性材料可采用本领域公知的用于锂离子电池的正极活性材料。作为示例，正极活性材料可包括以下材料中的至少一种：橄榄石结构的含锂磷酸盐、锂过渡金属氧化物及其各自的改性化合物。但本申请并不限定于这些 材料，还可以使用其他可被用作锂离子电池正极活性材料的传统材料。这些正极活性材料可以仅单独使用一种，也可以将两种以上组合使用。其中，锂过渡金属氧化物的示例可包括但不限于锂钴氧化物(如LiCoO2)、锂镍氧化物(如LiNiO2)、锂锰氧化物(如LiMnO2、LiMn2O4)、锂镍钴氧化物、锂锰钴氧化物、锂镍锰氧化物、锂镍钴锰氧化物(如LiNi1/3Co1/3Mn1/3O2(也可以简称为NCM333)、LiNi0.5Co0.2Mn0.3O2(也可以简称为NCM523)、LiNi0.5Co0.25Mn0.25O2(也可以简称为NCM211)、LiNi0.6Co0.2Mn0.2O2(也可以简称为NCM622)、LiNi0.8Co0.1Mn0.1O2(也可以简称为NCM811)、锂镍钴铝氧化物(如LiNi0.85Co0.15Al0.05O2)及其改性化合物等中的至少一种。橄榄石结构的含锂磷酸盐的示例可包括但不限于磷酸铁锂(如LiFePO4(也可以简称为LFP))、磷酸铁锂与碳的复合材料、磷酸锰锂(如LiMnPO4)、磷酸锰锂与碳的复合材料、磷酸锰铁锂、磷酸锰铁锂与碳的复合材料中的至少一种。
在一些实施方式中，正极膜层还可选地包括粘结剂。作为示例，粘结剂可以包括聚偏氟乙烯(PVDF)、聚四氟乙烯(PTFE)、偏氟乙烯-四氟乙烯-丙烯三元共聚物、偏氟乙烯-六氟丙烯-四氟乙烯三元共聚物、四氟乙烯-六氟丙烯共聚物及含氟丙烯酸酯树脂中的至少一种。
在一些实施方式中，正极膜层还可选地包括导电剂。作为示例，导电剂可以包括超导碳、乙炔黑、炭黑、科琴黑、碳点、碳纳米管、石墨烯及碳纳米纤维中的至少一种。
在一些实施方式中，可以通过以下方式制备正极极片：将上述用于制备正极极片的组分，例如正极活性材料、导电剂、粘结剂和任意其他的组分分散于溶剂(例如N-甲基吡咯烷酮)中，形成正极浆料；将正极浆料涂覆在正极集流体上，经烘干、冷压等工序后，即可得到正极极片。
[负极极片]
负极极片包括负极集流体以及设置在负极集流体至少一个表面上的负极膜层，所述负极膜层包括负极活性材料。
作为示例，负极集流体具有在其自身厚度方向相对的两个表面，负极膜层设置在负极集流体相对的两个表面中的任意一者或两者上。
在一些实施方式中，所述负极集流体可采用金属箔片或复合集流体。例如， 作为金属箔片，可以采用铜箔。复合集流体可包括高分子材料基层和形成于高分子材料基材至少一个表面上的金属层。复合集流体可通过将金属材料(铜、铜合金、镍、镍合金、钛、钛合金、银及银合金等)形成在高分子材料基材(如聚丙烯(PP)、聚对苯二甲酸乙二醇酯(PET)、聚对苯二甲酸丁二醇酯(PBT)、聚苯乙烯(PS)、聚乙烯(PE)等的基材)上而形成。
在一些实施方式中，负极活性材料可采用本领域公知的用于电池的负极活性材料。作为示例，负极活性材料可包括以下材料中的至少一种：人造石墨、天然石墨、软炭、硬炭、硅基材料、锡基材料和钛酸锂等。所述硅基材料可包括单质硅、硅氧化合物、硅碳复合物、硅氮复合物以及硅合金中的至少一种。所述锡基材料可包括单质锡、锡氧化合物以及锡合金中的至少一种。但本申请并不限定于这些材料，还可以使用其他可被用作电池负极活性材料的传统材料。这些负极活性材料可以仅单独使用一种，也可以将两种以上组合使用。
在一些实施方式中，负极膜层还可选地包括粘结剂。所述粘结剂可包括丁苯橡胶(SBR)、聚丙烯酸(PAA)、聚丙烯酸钠(PAAS)、聚丙烯酰胺(PAM)、聚乙烯醇(PVA)、海藻酸钠(SA)、聚甲基丙烯酸(PMAA)及羧甲基壳聚糖(CMCS)中的至少一种。
在一些实施方式中，负极膜层还可选地包括导电剂。导电剂可包括超导碳、乙炔黑、炭黑、科琴黑、碳点、碳纳米管、石墨烯及碳纳米纤维中的至少一种。
在一些实施方式中，负极膜层还可选地包括其他助剂，例如增稠剂(如羧甲基纤维素钠(CMC-Na))等。
在一些实施方式中，可以通过以下方式制备负极极片：将上述用于制备负极极片的组分，例如负极活性材料、导电剂、粘结剂和任意其他组分分散于溶剂(例如去离子水)中，形成负极浆料；将负极浆料涂覆在负极集流体上，经烘干、冷压等工序后，即可得到负极极片。
[隔离膜]
在一些实施方式中，电池单体中还包括隔离膜。本申请对隔离膜的种类没有特别的限制，可以选用任意公知的具有良好的化学稳定性和机械稳定性的多孔结构隔离膜。
在一些实施方式中，隔离膜的材质可包括玻璃纤维、无纺布、聚乙烯、聚丙烯及聚偏二氟乙烯中的至少一种。隔离膜可以是单层薄膜，也可以是多层复合薄膜，没有特别限制。在隔离膜为多层复合薄膜时，各层的材料可以相同或不同，没有特别限制。
在一些实施方式中，正极极片、负极极片和隔离膜可通过卷绕工艺或叠片工艺制成电极组件。
在一些实施方式中，电池单体可包括外包装。该外包装可用于封装上述电极组件及电解液。
在一些实施方式中，电池单体的外包装可以是硬壳，例如硬塑料壳、铝壳、钢壳等。电池单体的外包装也可以是软包，例如袋式软包。软包的材质可以是塑料，作为塑料，可列举出聚丙烯、聚对苯二甲酸丁二醇酯以及聚丁二酸丁二醇酯等。
本申请对电池单体的形状没有特别的限制，其可以是圆柱形、方形或其他任意的形状。例如，图1是作为一个示例的方形结构的电池单体20。
在一些实施方式中，参照图2，外包装可包括壳体21和盖板23。其中，壳体21可包括底板和连接于底板上的侧板，底板和侧板围合形成容纳腔。壳体21具有与容纳腔连通的开口，盖板23能够盖设于所述开口，以封闭所述容纳腔。正极极片、负极极片和隔离膜可经卷绕工艺或叠片工艺形成电极组件22。电极组件22封装于容纳腔内。电解液浸润于电极组件22中。电池单体20所含电极组件22的数量可以为一个或多个，本领域技术人员可根据具体实际需求进行选择。
在一些实施方式中，电池10可以包括多个电池单体20。例如，如图3所示，为本申请一个实施例的一种电池10的结构示意图，电池10可以包括多个电池单体20。电池10还可以包括箱体11，箱体11内部为中空结构，多个电池单体20容纳于箱体11内。例如，多个电池单体20相互并联或串联或混联组合后置于箱体11内。
可选地，电池10还可以包括其他结构，在此不再一一赘述。例如，该电池10还可以包括汇流部件，汇流部件用于实现多个电池单体20之间的电连接，例如并联或串联或混联。具体地，汇流部件可通过连接电池单体20的电极端子实现电池单体20之间的电连接。进一步地，汇流部件可通过焊接固定于电池单体20的电极端子。多个电池单体20的电能可进一步通过导电机构穿过箱体11而引出。可选地，导电机构也可 属于汇流部件。
根据不同的电力需求，电池单体20的数量可以设置为任意数值。多个电池单体20可通过串联、并联或混联的方式连接以实现较大的容量或功率。由于每个电池10中包括的电池单体20的数量可能较多，为了便于安装，可以将电池单体20分组设置，每组电池单体20组成电池模块。电池模块中包括的电池单体20的数量不限，可以根据需求设置。电池可以包括多个电池模块，这些电池模块可通过串联、并联或混联的方式进行连接。
另外，本申请还提供一种用电装置，该用电装置包括本申请提供的电池单体、电池模块或电池中的至少一种。电池单体、电池模块或电池可以用作该用电装置的电源，也可以用作该用电装置的能量存储单元。该用电装置可以包括移动设备(例如手机、笔记本电脑等)、电动车辆(例如纯电动车、混合动力电动车、插电式混合动力电动车、电动自行车、电动踏板车、电动高尔夫球车、电动卡车等)、电气列车、船舶及卫星、储能系统等，但不限于此。
作为该用电装置，可以根据其使用需求来选择电池单体、电池模块或电池。
图4是作为一个示例的用电装置。该用电装置为纯电动车、混合动力电动车、或插电式混合动力电动车等。为了满足该用电装置对电池单体的高功率和高能量密度的需求，可以采用电池或电池模块。
作为另一个示例的装置可以是手机、平板电脑、笔记本电脑等。该装置通常要求轻薄化，可以采用电池单体作为电源。
[实施例]
以下，说明本申请的实施例。下面描述的实施例是示例性的，仅用于解释本申请，而不能理解为对本申请的限制。实施例中未注明具体技术或条件的，按照本领域内的文献所描述的技术或条件或者按照产品说明书进行。所用试剂或仪器未注明生产厂商者，均为可以通过市购获得的常规产品。
(1)化合物的制备
化合物1的制备：
具体步骤：在三口瓶中，加入羰基二咪唑(1mol)，乙腈作为溶剂，加入赤藓糖醇(1.1mol)，在60-80℃的反应温度下反应2h；反应结束后，将过量赤藓糖醇析出除去，分离得到产物1。然后在四氢呋喃(THF)溶液中，加入产物1(1mol)，三乙胺(2.1mol)，在0℃下缓慢滴加PCl3(1.05mol)，然后室温下反应2h；过滤除去三乙胺盐酸盐，继续加入三乙胺(1.1mol)，然后在0℃下缓慢滴加甲醇(1.1mol)，在室温下反应2h，反应结束后，通入氧气氧化，在室温下反应48h，最终过柱分离出化合物1。
化合物2的制备：在合成得到上述化合物1的基础上，在PFA反应罐中，加入化合物1，在50℃下通入氟气和氮气的混合气体(氟气和氮气的体积比为3:7)，以350ml/min的速率通气，反应0.5h后，将反应产物进行柱层析分离，得到化合物2。
化合物3的制备：在合成得到上述化合物1的基础上，在三口烧瓶中，加入化合物1(0.1mol)，加入铂炭添加剂(1g)，在50℃下滴加双氧水(0.1mol)，反应1h，将反应产物进行柱层析分离，得到化合物3。
化合物4的制备：
具体步骤：在三口瓶中，加入羰基二咪唑(1mol)，乙腈作为溶剂，加入赤藓糖醇(1.1mol)，在60-80℃的反应温度下反应2h；反应结束后，将过量赤藓糖醇析出除去，分离得到产物1。然后在四氢呋喃(THF)溶液中，加入产物1(1mol)，三乙胺(2.1mol)，在0℃下缓慢滴加PCl3(1.05mol)，然后室温下反应2h；过滤除去三乙胺盐酸盐，继续加入三乙胺(1.1mol)，然后在0℃下缓慢滴加三氟乙醇(1.1mol)，在室温下反应2h，反应结束后，通入氧气氧化，在室温下反应48h，过柱分离出产物2。在三口烧瓶中，加入产物2(0.1mol)，加入铂炭添加剂(1g)，在50℃下滴加双氧水(0.1mol)，滴加结束后反应1h，然后经过柱层析分离得到化合物4。
化合物5的制备：
具体步骤：在三口瓶中，加入羰基二咪唑(1mol)，乙腈作为溶剂，加入赤藓糖醇(1.1mol)，在60-80℃的反应温度下反应2h；反应结束后，将过量赤藓糖醇析出除去，分离得到产物1。然后在四氢呋喃(THF)溶液中，加入产物1(1mol)，三乙胺(2.1mol)，在0℃下缓慢滴加PCl3(1.05mol)，然后室温下反应2h；过滤除去三乙胺盐酸盐，继续加入三乙胺(1.1mol)，然后在0℃下缓慢滴加烯丙基甲醇(1.1mol)，在室温下反应2h，反应结束后，通入氧气氧化，在室温下反应48h，过柱分离出产物3。在三口烧瓶中，加入产物3(0.1mol)，加入铂炭添加剂(1g)，在50℃下滴加双氧水(0.1mol)，滴加结束后反应1h，然后经过柱层析分离得到化合物5。
化合物6的制备：
具体步骤：在三口瓶中，加入羰基二咪唑(1mol)，乙腈作为溶剂，加入(1.1mol)，在60-80℃的反应温度下反应2h；反应结束后，将过量赤藓糖醇析出除去，分离得到产物4。然后在四氢呋喃(THF)溶液中，加入产物4(1mol)，三乙胺(2.1mol)，在0℃下缓慢滴加PCl3(1.05mol)，然后室温下反应2h；过滤除去三乙胺盐酸盐，继续加入三乙胺(1.1mol)，然后在0℃下缓慢滴加甲醇(1.1mol)，在室温下反应2h，反应结束后，通入氧气氧化，在室温下反应48h，最终过柱分离出产物5。在PFA反应罐中，加入产物5，在50℃下通入氟气和氮气的混合气体(氟气和氮气的体积比为3:7)，以350ml/min的速率通气，反应0.5h后，将反应产物进行柱层析分离，得到化合物6。
化合物7的制备：
具体步骤：在三口瓶中，加入硫酰咪唑(1mol)，乙腈作为溶剂，加入赤藓糖醇(1.1mol)，在60-80℃的反应温度下反应2h；反应结束后，将过量硫酰咪唑析出除去，分离得到产物1’。然后在四氢呋喃(THF)溶液中，加入产物1’(1mol)，三乙胺(2.1mol)，在0℃下缓慢滴加PCl3(1.05mol)，然后室温下反应2h，得到产物3’。在三口烧瓶中加入产物3’(0.1mol)，乙腈作为溶剂，加入三乙胺(0.11mol)，加入氢氧化锂，室温下反应1h，以重结晶的方式得到产物4’。在三口烧瓶中加入产物4’(0.1mol)，乙腈作为溶剂，加入三氯化钌，在氮气氛围中，15℃下滴加次氯酸钠，反应10min后，将反应产物进行柱层析分离，得到化合物7。
化合物8的制备：
具体步骤：在三口瓶中，加入硫酰咪唑(1mol)，乙腈作为溶剂，加入赤藓糖醇(1.1mol)，在60-80℃的反应温度下反应2h；反应结束后，将过量硫酰咪唑析出除去，分离得到产物1’。然后在四氢呋喃(THF)溶液中，加入产物1’(1mol)，三乙胺(2.1mol)，在0℃下缓慢滴加PCl3(1.05mol)，然后室温下反应2h；过滤除去三乙胺盐酸盐，继续加入三乙胺(1.1mol)，然后在0℃下缓慢滴加三氟乙醇(1.1mol)，在室温下反应2h，得到产物5’。在三口烧瓶中加入产物5’(0.1mol)，乙腈作为溶剂，加入三氯化钌，在氮气氛围中，15℃下滴加次氯酸钠，反应10min后，将反应产物进行柱层析分离，得到化合物8。
化合物9的制备：
具体步骤：在三口瓶中，加入硫酰咪唑(1mol)，乙腈作为溶剂，加入赤藓糖醇(1.1mol)，在60-80℃的反应温度下反应2h；反应结束后，将过量硫酰咪唑析出除去，分离得到产物1’。然后在四氢呋喃(THF)溶液中，加入产物1’(1mol)，三乙胺(2.1mol)，在0℃下缓慢滴加PCl3(1.05mol)，然后室温下反应2h；过滤除去三乙胺盐酸盐，继续加入三乙胺(1.1mol)，然后在0℃下缓慢滴加甲醇(1.1mol)，在室温下反应2h，得到产物2’。在三口烧瓶中加入产物2’(0.1mol)，乙腈作为溶剂，加入三氯化钌，在氮气氛围中，15℃下滴加次氯酸钠，反应10min后，将反应产物进行柱层析分离，得到化合物9。
化合物10的制备：
具体步骤：在三口瓶中，加入硫酰咪唑(1mol)，乙腈作为溶剂，加入(1.1mol)，在60-80℃的反应温度下反应2h；反应结束后，将过量硫酰咪唑析出除去，分离得到产物6’。然后在四氢呋喃(THF)溶液中，加入产物6’(1mol)，三乙胺(2.1mol)，在0℃下缓慢滴加PCl3(1.05mol)，然后室温下反应2h；过滤除去三乙胺盐酸盐，继续加入三乙胺(1.1mol)，然后在0℃下缓慢滴加甲醇(1.1mol)，在室温下反应2h，得到产物7’。在三口烧瓶中加入产物7’(0.1mol)，乙腈作为溶剂，加入三氯化钌，在氮气氛围中，15℃下滴加次氯酸钠，反应10min后，将反应产物进行柱层析分离，得到化合物10。
化合物11的制备：
具体步骤：在三口瓶中，加入硫酰咪唑(1mol)，乙腈作为溶剂，加入(1.1mol)，在60-80℃的反应温度下反应2h；反应结束后，将过量硫酰咪唑析出除去，分离得到产物6’。然后在四氢呋喃(THF)溶液中，加入产物6’(1mol)，三乙胺(2.1mol)，在0℃下缓慢滴加PCl3(1.05mol)，然后室温下反应2h；过滤除去三乙胺盐酸盐，继续加入三乙胺(1.1mol)，然后在0℃下缓慢滴加三氟乙醇(1.1mol)，在室温下反应2h，得到产物8’。在三口烧瓶中加入产物8’(0.1mol)，乙腈作为溶剂，加入三氯化钌，在氮气氛围中，15℃下滴加次氯酸钠，反应10min后，将反应产物进行柱层析分离，得到化合物11。
(2)电解液的制备：在氩气气氛手套箱中(H2O<0.1ppm，O2<0.1ppm)， 将有机溶剂EC和EMC按照体积比3：7混合均匀，加入1M六氟磷酸锂(LiPF6)溶解于有机溶剂中，加入第一添加剂溶解于有机溶剂中，搅拌均匀，得到相应的电解液。
(3)正极极片的制备：将正极活性材料LiNi0.5Mn0.38Co0.12O2、导电剂乙炔黑、粘结剂聚偏二氟乙烯(PVDF)按重量比为96:2:2溶于溶剂N-甲基吡咯烷酮(NMP)中，充分搅拌混合均匀后得到正极浆料；之后将正极浆料均匀涂覆于正极集流体上，之后经过烘干、冷压、分切，得到正极极片。
(4)负极极片的制备：将活性物质人造石墨、导电剂乙炔黑、粘结剂丁苯橡胶(SBR)、增稠剂羧甲基纤维素钠(CMC)按照重量比为96:1.5:1.5:1溶于溶剂去离子水中与溶剂去离子水均匀混合后制备成负极浆料；然后将负极浆料均匀涂覆在负极集流体铜箔上，烘干后得到负极膜片，再经过冷压、分切得到负极极片。
(5)隔离膜的制备：以常规的聚丙烯膜作为隔离膜。
(6)锂离子电池的组装：将正极片、隔离膜、负极片按顺序叠好，使隔离膜处于正、负极片之间起到隔离的作用，然后卷绕得到电极组件；将电极组件置于电池壳体中，干燥后注入电解液，再经过化成、静置等工艺制得锂离子电池。
[实施例1]
第一添加剂为化合物1，按照上述制备电解液的方法，制得含有化合物1的电解液1，该化合物1在电解液1中的质量含量为1％。再按照上述锂离子电池组装的方法，制得含有电解液1的锂离子电池1，对应实施例1。
[实施例2]
第一添加剂为化合物2，按照上述制备电解液的方法，制得含有化合物2的电解液2，该化合物2在电解液2中的质量含量为1％，再按照上述锂离子电池组装的方法，制得含有电解液2的锂离子电池2，对应实施例2。
[实施例3]
第一添加剂为化合物3，按照上述制备电解液的方法，制得含有化合物3的电解液3，该化合物3在电解液3中的质量含量为1％，再按照上述锂离子电池组装的方法，制得含有电解液3的锂离子电池3，对应实施例3。
[实施例4]
第一添加剂为化合物4，按照上述制备电解液的方法，制得含有化合物4的电解液4，该化合物4在电解液4中的质量含量为1％，再按照上述锂离子电池组装的 方法，制得含有电解液4的锂离子电池4，对应实施例4。
[实施例5]
第一添加剂为化合物5，按照上述制备电解液的方法，制得含有化合物5的电解液5，该化合物5在电解液5中的质量含量为1％，再按照上述锂离子电池组装的方法，制得含有电解液5的锂离子电池5，对应实施例5。
[实施例6]
第一添加剂为化合物6，按照上述制备电解液的方法，制得含有化合物6的电解液6，该化合物6在电解液6中的质量含量为1％，再按照上述锂离子电池组装的方法，制得含有电解液6的锂离子电池6，对应实施例6。
[实施例7和8]
实施例7和8相对于实施例4，不同的是加到电解液中的化合物4的质量不同，制得的电解液7和电解液8中，化合物4的质量含量分别为10％和0.0001％，再按照上述锂离子电池组装的方法，制得含有电解液7的锂离子电池7和含有电解液8的锂离子电池8，对应实施例7和8。
[实施例9]
实施例9相对于实施例4，不同的是在实施例4的基础上，还添加了质量含量为20ppm的SO2，制得锂离子电池9，对应实施例9。
[实施例10]
实施例10相对于实施例9，不同的是在实施例9的基础上，还添加了质量含量为5ppm的2，6-二叔丁基对甲苯酚作为阻聚剂，制得锂离子电池10，对应实施例10。
[实施例11]
实施例11相对于实施例10，不同的是在实施例10的基础上，还添加了质量含量为1％的双氟代碳酸乙烯酯(DFEC)，制得锂离子电池11，对应实施例11。
[实施例12]
实施例12相对于实施例4，不同的是在实施例4的基础上，还添加了质量含量为900ppm的SO2，制得锂离子电池12，对应实施例12。
[实施例13]
实施例13相对于实施例9，不同的是在实施例9的基础上，还添加了质量含量为30ppm的2，6-二叔丁基对甲苯酚作为阻聚剂，制得锂离子电池13，对应实施例13。
[实施例14]
第一添加剂为化合物7，按照上述制备电解液的方法，制得含有化合物7的电解液14，该化合物7在电解液14中的质量含量为1％，再按照上述锂离子电池组装的方法，制得含有电解液14的锂离子电池14，对应实施例14。
[实施例15]
第一添加剂为化合物8，按照上述制备电解液的方法，制得含有化合物8的电解液15，该化合物8在电解液15中的质量含量为1％，再按照上述锂离子电池组装的方法，制得含有电解液15的锂离子电池15，对应实施例15。
[实施例16]
第一添加剂为化合物9，按照上述制备电解液的方法，制得含有化合物9的电解液16，该化合物9在电解液16中的质量含量为1％，再按照上述锂离子电池组装的方法，制得含有电解液16的锂离子电池16，对应实施例16。
[实施例17]
第一添加剂为化合物10，按照上述制备电解液的方法，制得含有化合物17的电解液17，该化合物10在电解液17中的质量含量为1％，再按照上述锂离子电池组装的方法，制得含有电解液17的锂离子电池17，对应实施例17。
[实施例18]
第一添加剂为化合物11，按照上述制备电解液的方法，制得含有化合物11的电解液18，该化合物11在电解液18中的质量含量为1％，再按照上述锂离子电池组装的方法，制得含有电解液18的锂离子电池18，对应实施例18。
[实施例19和20]
实施例19和20相对于实施例16，不同的是加到电解液中的化合物9的质量不同，制得的电解液19和电解液20中，化合物9的质量含量分别为10％和0.0001％，再按照上述锂离子电池组装的方法，制得含有电解液19的锂离子电池19和含有电解液20的锂离子电池20，分别对应实施例19和20。
[实施例21]
实施例21相对于实施例16，不同的是在实施例16的基础上，还添加了质 量含量为20ppm的SO2，制得锂离子电池21，对应实施例21。
[实施例22]
实施例22相对于实施例21，不同的是在实施例21的基础上，还添加了质量含量为5ppm的苯二酚作为阻聚剂，制得锂离子电池22，对应实施例22。
[实施例23]
实施例23相对于实施例22，不同的是在实施例22的基础上，还添加了质量含量为1％的硫酸乙烯酯(DTD)，制得锂离子电池23，对应实施例23。
[实施例24]
实施例24相对于实施例16，不同的是在实施例16的基础上，还添加了质量含量为20ppm的CO2，制得锂离子电池24，对应实施例24。
[实施例25]
实施例25相对于实施例16，不同的是在实施例16的基础上，还添加了质量含量为900ppm的SO2，制得锂离子电池25，对应实施例25。
[实施例26]
实施例26相对于实施例22，不同的是实施例26中添加了质量含量为30ppm的苯二酚作为阻聚剂，制得锂离子电池26，对应实施例26。
[对比例1]
第一添加剂为VC，按照上述制备电解液的方法，制得含有VC的电解液1’，VC在电解液1’中的质量含量为1％，再按照上述锂离子电池组装的方法，制得含有电解液1’的锂离子电池1’，对应对比例1。
[对比例2]
第一添加剂为DTD，按照上述制备电解液的方法，制得含有DTD的电解液2’，DTD在电解液2’中的质量含量为1％，再按照上述锂离子电池组装的方法，制得含有电解液2’的锂离子电池2’，对应对比例2。
不同实施例的产品参数详见表1。
表1：对比例及不同实施例的产品参数
接下来，对相关参数的测试过程进行说明。
1、锂离子电池的存储性能测试
在25℃下，将锂离子电池以0.5C恒流充电至4.5V，然后以4.5V恒压充电至电流小于0.05C，然后将锂离子电池放到60℃存储，每隔5天取出进行满充后再存储，容量衰减至80％时停测，记录高温存储时间。
2、锂离子电池的循环性能测试
在45℃下，将锂离子电池以1C恒流充电至4.5V，然后以4.5V恒压充电至电流小于0.05C，然后将锂离子电池以1C恒流放电至2.8V，此为一个充放电过程。如此反复进行充电和放电，计算锂离子容量保持率为80％的循环圈数。
其中，锂离子电池循环n次后的容量保持率(％)＝(第n次循环的放电容量/首次循环的放电容量)×100％。
按照上述方法分别对制备得到的对比例1-2、实施例1-26进行电池性能测试，结果详见表2。
表2：对比例及不同实施例的性能测试结果

从对比例1-2分别与实施例1-6的结果比较可知，在电解液中加入本申请提供的同时包含环状碳酸酯和环状磷酸酯结构的化合物，锂离子电池的循环性能显著提高，以及锂离子电池在高温下的循环性能的衰减速度明显降低，从而提高了锂离子电池的使用寿命，锂离子电池的存储寿命也有所提升。
从对比例1-2分别与实施例14-18的结果比较可知，在电解液中加入本申请提供的同时包含环状硫酸酯和环状磷酸酯结构的化合物，锂离子电池的循环性能显著提高，以及锂离子电池在高温下的循环性能的衰减速度明显降低，从而提高了锂离子电池的使用寿命，锂离子电池的存储寿命也有所提升。
从实施例1-6的结果比较可知，在化合物的结构中引入氟原子，或者是引入烯基，化合物共聚形成的界面膜具有更好的性能，可以进一步提升锂离子电池的循环性能、使用寿命以及存储寿命。
从实施例4与实施例7、8的结果比较以及实施例16与实施例19、20的结果比较可知，第一添加剂在电解液中的质量含量不宜过高也不宜过低，通过将第一添加剂在电解液中的质量含量控制在合适的范围内能够进一步提升电池的循环稳定性和使用寿命。
从实施例4与实施例9、12的结果比较以及实施例16与实施例21、24、25的结果比较可知，在电解液中添加适量的SO2或CO2，可以促进形成含有硫酸盐/碳酸盐以及聚磷酸酯-聚硫酸酯和/或聚磷酸酯-聚碳酸酯的无机-有机致密界面膜，该界面膜更致密，更好阻止电解液中其他分子的共嵌入，避免其他分子共嵌入对电极材料的破坏，从而提升锂离子电池的循环性能和使用寿命。
从实施例9与实施例10、13的结果比较以及实施例21与实施例22、26的结果比较可知，在电解液中添加适量的阻聚剂，以防止在电池的运输过程中，电解液中的物质在充分接触的情况下发生化学反应而破坏电解液的组成成分，提升锂离子电池的循环性能和使用寿命；过量的阻聚剂会影响第一添加剂的共聚反应，影响电池在 化成阶段的成膜，不能在电极极片和电解液之间形成稳定的界面膜，从而影响锂离子电池的循环性能和存储寿命。
从实施例10与实施例11的结果比较可知，在电解液中添加DFEC，DFEC在电化学反应下形成单体活性自由基，进而提高第一添加剂共聚形成共聚物的反应转化率，使得初始形成的共聚物界面膜分子量更大，更为致密，可以提升锂离子电池的循环性能和使用寿命。
从实施例22与实施例23的结果比较可知，在电解液中添加DTD，DTD在电化学反应下形成单体活性自由基，进而提高第一添加剂共聚形成共聚物的反应转化率，使得初始形成的共聚物界面膜分子量更大，更为致密，可以提升锂离子电池的循环性能和使用寿命。
需要说明的是，本申请不限定于上述实施方式。上述实施方式仅为示例，在本申请的技术方案范围内具有与技术思想实质相同的构成、发挥相同作用效果的实施方式均包含在本申请的技术范围内。此外，在不脱离本申请主旨的范围内，对实施方式施加本领域技术人员能够想到的各种变形、将实施方式中的一部分构成要素加以组合而构筑的其它方式也包含在本申请的范围内。

Claims (18)

  1. 一种电解液，包括：
    第一添加剂，所述第一添加剂包括至少含有式(I)和式(II)所示的基团的化合物、至少含有式(I)和式(Ш)所示的基团的化合物中的至少一种；
    其中，R1、R3和R4各自独立地包括饱和或不饱和的烃基中的至少一种，R2包括F、OLi、OCH2CF3、OCH3、OCH2CH2＝CH2、OCH2CH2CH2＝CH2、OSi(OCH3)3、OSi(OCH2CH2＝CH2)3或OSi(CH2＝CH2)3，X1和X2包括O或CH2且X1和X2不同时为CH2。
  2. 根据权利要求1所述的电解液，其中，所述第一添加剂在所述电解液中的质量含量为0.0001％～10％，可选地，所述第一添加剂在所述电解液中的质量含量为0.01％～5％。
  3. 根据权利要求1或2所述的电解液，其中，所述第一添加剂包括式(IV)、式(V)、式(VI)、式(VII)所示的化合物中的至少一种：

    其中，R5和R6各自独立地包括H、卤原子、取代或未取代的烃基、含有不饱和双键或三键的基团中的至少一种，R7和R8各自独立地包括碳原子数为1-6的饱和或不饱和的烃基、单键中的至少一种，x的取值为1-5中任一自然数，y的取值为0-5中任一自然数。
  4. 根据权利要求3所述的电解液，其中，R5和R6各自独立地包括H、F、碳原子数为1-3的直链烷基或支链烷基、碳原子数为1-3的直链全氟取代烷基或支链全氟取代烷基、含有不饱和双键的碳原子数为1-3的基团中的至少一种。
  5. 根据权利要求3或4所述的电解液，其中，R7和R8各自独立地包括碳原子数为1-3的饱和或不饱和的烃基中的至少一种。
  6. 根据权利要求1至5中任一项所述的电解液，其中，所述第一添加剂包括以下物质中的至少一种：




  7. 根据权利要求1至6中任一项所述的电解液，其中，所述电解液还包括第二添加剂，所述第二添加剂包括碳酸酯、磺酸酯、硫酸酯、磷酸酯中的至少一种。
  8. 根据权利要求7所述的电解液，其中，所述第二添加剂包括碳酸亚乙烯酯、双氟代碳酸乙烯酯、氟代碳酸乙烯酯、碳酸乙烯亚乙酯、丙磺酸内酯、丙烯基-1,3-磺酸内酯、硫酸乙烯酯、双硫酸乙烯酯、三(2,2,2-三氟乙基)磷酸酯、三烯丙基磷酸酯、二氟磷酸锂中的至少一种。
  9. 根据权利要求1至8中任一项所述的电解液，其中，所述电解液还包括第三添加剂，所述第三添加剂包括SO2、CO2中的至少一种。
  10. 根据权利要求9所述的电解液，其中，所述第三添加剂在所述电解液中的质量含量为10～1000ppm。
  11. 根据权利要求1至10中任一项所述的电解液，其中，所述电解液还包括阻聚剂，可选地，所述阻聚剂包括对苯二酚、2,6-二叔丁基对甲苯酚中的至少一种。
  12. 根据权利要求11所述的电解液，其中，所述阻聚剂在所述电解液中的质量含量小于20ppm，可选地，所述阻聚剂在所述电解液中的质量含量小于10ppm。
  13. 根据权利要求1至12中任一项所述的电解液，其中，所述电解液还包括溶剂，所述溶剂在25℃时的相对介电常数大于2且粘度小于2mPa.s。
  14. 根据权利要求13所述的电解液，其中，所述溶剂包括碳酸酯、羧酸酯、醚、砜、氟代碳酸酯、氟代羧酸酯、氟代醚、氟代砜中的至少一种。
  15. 根据权利要求1至14中任一项所述的电解液，其中，所述电解液还包括金属盐，所述金属盐包括六氟磷酸锂、四氟硼酸锂、高氯酸锂、六氟砷酸锂、双氟磺酰亚胺锂、双三氟甲磺酰亚胺锂、三氟甲磺酸锂、二氟草酸硼酸锂、二草酸硼酸锂、二氟磷酸锂、二氟二草酸磷酸锂、四氟草酸磷酸锂中的至少一种，可选地，所述金属盐包括六氟磷酸锂、双氟磺酰亚胺锂中的至少一种。
  16. 根据权利要求1至15中任一项所述的电解液，其中，所述电解液的酸度值小于800ppm。
  17. 一种电池，包括权利要求1至16中任一项所述的电解液。
  18. 一种用电装置，包括权利要求17所述的电池，所述电池用于提供电能。
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