WO2023123030A1 - 电化学装置和电子装置 - Google Patents

电化学装置和电子装置 Download PDF

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Publication number
WO2023123030A1
WO2023123030A1 PCT/CN2021/142400 CN2021142400W WO2023123030A1 WO 2023123030 A1 WO2023123030 A1 WO 2023123030A1 CN 2021142400 W CN2021142400 W CN 2021142400W WO 2023123030 A1 WO2023123030 A1 WO 2023123030A1
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Prior art keywords
positive electrode
compound
electrochemical device
lithium
electrolyte
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PCT/CN2021/142400
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English (en)
French (fr)
Inventor
张青文
王可飞
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宁德新能源科技有限公司
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Priority to PCT/CN2021/142400 priority Critical patent/WO2023123030A1/zh
Priority to CN202180027070.4A priority patent/CN115380408A/zh
Publication of WO2023123030A1 publication Critical patent/WO2023123030A1/zh

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
    • H01M10/0564—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of organic materials only
    • H01M10/0566—Liquid materials
    • H01M10/0567—Liquid materials characterised by the additives
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/42—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
    • H01M10/4235—Safety or regulating additives or arrangements in electrodes, separators or electrolyte
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/60—Selection of substances as active materials, active masses, active liquids of organic compounds
    • H01M4/602—Polymers
    • H01M4/606—Polymers containing aromatic main chain polymers
    • 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
    • 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 energy storage, in particular to an electrochemical device and an electronic device, especially a lithium ion battery.
  • the embodiments of the present application solve the problems existing in the prior art to some extent by providing an electrochemical device and an electronic device with improved float charging performance and safety.
  • the present application provides an electrochemical device, which includes: a positive electrode, a negative electrode and an electrolyte, the positive electrode includes a positive electrode current collector and a positive electrode active material layer formed on the positive electrode current collector, wherein:
  • the positive electrode active material layer includes poly(amic acid), and the electrolytic solution includes a difluorophosphite compound.
  • the content of the poly(amic acid) is a%; based on the weight of the electrolyte, the content of the difluorophosphite compound is b %; and a and b satisfy: 0.1 ⁇ a/b ⁇ 5.
  • a ranges from 0.5 to 5.
  • the value of b ranges from 0.1 to 5.
  • the poly(amic acid) includes a compound of formula I:
  • R is selected from C1-12 alkenyl or C6-12 aromatic ring
  • A is selected from single bond, C1-12 alkenyl or C6-12 aromatic ring;
  • n is an integer of 5-20.
  • the difluorophosphite compound includes a compound of formula II:
  • A is substituted or unsubstituted C1-10 alkyl or C3-10 cycloalkyl
  • the substituent When substituted, the substituent is halogen or cyano.
  • the difluorophosphite compound includes at least one of the following compounds:
  • the electrolyte solution further includes a compound containing a sulfur-oxygen double bond
  • the compound containing a sulfur-oxygen double bond includes at least one of the following compounds: cyclic sulfate, chain sulfate, chain Shaped sulfonate, cyclic sulfonate, chain sulfite or cyclic sulfite or compound of formula III:
  • L is selected from a single bond or methylene
  • n is an integer from 1 to 4.
  • n is an integer from 0 to 2;
  • p is an integer of 0 to 6.
  • the compound of formula III is selected from at least one of the following:
  • the content of the difluorophosphite compound is b%
  • the content of the compound containing sulfur and oxygen double bonds is c%
  • b and c satisfy: 1 ⁇ b+c ⁇ 8 and 0.4 ⁇ b/c ⁇ 5.
  • the content of the sulfur-oxygen double bond-containing compound is c%, and the value of c ranges from 0.1 to 8.
  • the value range of c is 0.1 to 1.5
  • the present application provides an electronic device comprising the electrochemical device according to the present application.
  • the specific combination of the positive electrode active material comprising poly(amic acid) and the electrolyte solution comprising difluorophosphite compound used in the present application can improve the interfacial stability of the positive electrode active material layer under thermal runaway, and can sufficiently inhibit electrochemical
  • the floating charge thickness of the device increases under high pressure and high temperature, which can effectively prevent safety problems such as combustion or explosion caused by thermal runaway of the battery.
  • a list of items linked by the term "at least one of” may mean any combination of the listed items.
  • the phrase "at least one of A and B” means only A; only B; or A and B.
  • the phrase "at least one of A, B, and C” means only A; or only B; only C; A and B (excluding C); A and C (excluding B); B and C (excluding A); or all of A, B, and C.
  • Item A may contain a single element or multiple elements.
  • Item B may contain a single element or multiple elements.
  • Item C may contain a single element or multiple elements.
  • the term "at least one of" has the same meaning as the term "at least one of”.
  • alkyl is intended to be a straight chain saturated hydrocarbon structure having from 1 to 20 carbon atoms. "Alkyl” is also contemplated as branched or cyclic hydrocarbon structures having from 3 to 20 carbon atoms. When an alkyl group having a specific number of carbons is specified, all geometric isomers having that number of carbons are intended to be encompassed; thus, for example, “butyl” is meant to include n-butyl, sec-butyl, iso-butyl, 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 etc.
  • alkenyl refers to a monovalent unsaturated hydrocarbon group which may be straight-chain or branched and which has at least one and usually 1, 2 or 3 carbon-carbon double bonds. Unless otherwise defined, such alkenyl groups typically contain 2 to 20 carbon atoms and include, for example, -C 2-4 alkenyl, -C 2-6 alkenyl, and -C 2-10 alkenyl. Representative alkenyl groups include, for example, ethenyl, n-propenyl, isopropenyl, n-but-2-enyl, but-3-enyl, n-hex-3-enyl, and the like.
  • aromatic ring means a monovalent aromatic hydrocarbon having a single ring (eg, phenyl) or fused rings.
  • Fused ring systems include those that are fully unsaturated (eg, naphthalene) as well as those that are partially unsaturated (eg, 1,2,3,4-tetrahydronaphthalene).
  • the aryl ring typically contains 6 to 26 carbon ring atoms and includes, for example, -C 6-10 aryl.
  • aryl groups include, for example, phenyl, methylphenyl, propylphenyl, isopropylphenyl, benzyl, and naphthalen-1-yl, naphthalen-2-yl, and the like.
  • cycloalkyl encompasses cyclic alkyl groups.
  • the cycloalkyl group may be a cycloalkyl group of 3-20 carbon atoms, a cycloalkyl group of 6-20 carbon atoms, a cycloalkyl group of 3-12 carbon atoms, or a cycloalkyl group of 3-6 carbon atoms.
  • cycloalkyl may be cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, and the like.
  • cycloalkyl groups may be optionally substituted.
  • halogen refers to the elements of group VIIA of the periodic table of chemical elements, including fluorine (F), chlorine (Cl), bromine (Br), iodine (I) and astatine (At).
  • the ways to improve the safety of electrochemical devices mainly include: adding flame retardant additives in the electrolyte; and using thermal closed-cell separators or functional coatings diaphragm.
  • adding flame retardant additives in the electrolyte will have a serious adverse effect on the electrochemical performance of lithium-ion batteries.
  • thermally closed-cell separators or functional coating separators can improve the safety of lithium-ion batteries and have little impact on the electrochemical performance of batteries during normal operation, they still cannot fundamentally control the thermal runaway rate of batteries.
  • the present application solves the above-mentioned problems by using a combination of a positive electrode active material including poly(amic acid) and an electrolyte solution including a difluorophosphite compound.
  • Poly(amic acid) can be converted into polyimide at temperatures above 160°C.
  • the poly(amic acid) in the positive electrode active material layer can quickly absorb heat, undergo a polymerization reaction, and generate polyimide with insulating function, thereby blocking the ions and particles of the positive electrode active material.
  • Electron transport, fast and efficient enhancement of lithium-ion battery safety can affect the float charge performance of Li-ion batteries.
  • difluorophosphite compounds in the electrolyte helps to improve the float performance of lithium-ion batteries, because there are a large number of intermolecular forces between poly(amic acid) and difluorophosphite compounds, thereby relieving the The effect of poly(amic acid) on the ion conductance in the transport of lithium ions at room temperature was studied.
  • poly(amic acid) and difluorophosphite compounds can form composite polymers, which are more effective for improving the float performance and safety of lithium-ion batteries. Therefore, the specific combination of the positive electrode active material and the electrolyte solution of the present application can significantly improve the float charge performance and safety of the electrochemical device.
  • the positive electrode includes a positive electrode current collector and a positive electrode active material layer formed on the positive electrode current collector.
  • the positive active material layer may be one or more layers.
  • the positive active material layer includes positive active materials, and each layer of the multilayer positive active materials may contain the same or different positive active materials.
  • a main feature of the electrochemical device of the present application is that the positive electrode active material layer includes poly(amic acid).
  • the poly(amic acid) comprises a compound of formula I:
  • R is selected from C1-12 alkenyl or C6-12 aromatic ring
  • A is selected from single bond, C1-12 alkenyl or C6-12 aromatic ring;
  • n is an integer of 5-20.
  • the poly(amic acid) comprises a compound of formula I-1 (BPDA/PDA PAA):
  • n is an integer from 5 to 20.
  • the content of the poly(amic acid) is a%, and the value of a ranges from 0.5 to 5. In some embodiments, a ranges from 1 to 3. In some embodiments, x is 0.5, 1, 2, 2.5, 3, 3.5, 4, 4.5, 5 or within a range consisting of any two of the above values. When the content of the poly(amic acid) in the positive electrode active material layer is within the above range, it is helpful to further improve the float charge performance and safety of the electrochemical device.
  • the type of positive electrode active material is not particularly limited, as long as it can store and release metal ions (for example, lithium ions) electrochemically.
  • the positive active material is a material containing lithium and at least one transition metal.
  • positive active materials may include, but are not limited to, lithium transition metal composite oxides and lithium transition metal phosphate compounds.
  • the transition metals in the lithium transition metal composite oxide include V, Ti, Cr, Mn, Fe, Co, Ni, Cu, and the like.
  • lithium transition metal composite oxides include lithium cobalt composite oxides such as LiCoO 2 , lithium nickel composite oxides such as LiNiO 2 , lithium manganese composite oxides such as LiMnO 2 , LiMn 2 O 4 , Li 2 MnO 4 , lithium nickel manganese cobalt composite oxides such as LiNi 1/3 Mn 1/3 Co 1/3 O 2 , LiNi 0.5 Mn 0.3 Co 0.2 O 2 , etc., in which a part of the transition metal atom which is the main body of these lithium transition metal composite oxides is Na, K, B, F, Al, Ti, V, Cr, Mn, Fe, Co, Li, Ni, Cu, Zn, Mg, Ga, Zr, Si, Nb, Mo, Sn, W and other elements substituted .
  • lithium transition metal composite oxides may include, but are not limited to, LiNi 0.5 Mn 0.5 O 2 , LiNi 0.85 Co 0.10 Al 0.05 O 2 , LiNi 0.33 Co 0.33 Mn 0.33 O 2 , LiNi 0.45 Co 0.10 Al 0.45 O 2 , LiMn 1.8 Al 0.2 O 4 and LiMn 1.5 Ni 0.5 O 4 etc.
  • combinations of lithium transition metal composite oxides include, but are not limited to, combinations of LiCoO 2 and LiMn 2 O 4 , wherein a part of Mn in LiMn 2 O 4 may be replaced by transition metals (for example, LiNi 0.33 Co 0.33 Mn 0.33 O 2 ), part of Co in LiCoO 2 can be replaced by transition metals.
  • the transition metals in the lithium-containing transition metal phosphate compound include V, Ti, Cr, Mn, Fe, Co, Ni, Cu, and the like.
  • lithium-containing transition metal phosphate compounds include iron phosphates such as LiFePO 4 , Li 3 Fe 2 (PO 4 ) 3 , LiFeP 2 O 7 , and cobalt phosphates such as LiCoPO 4 , wherein as these lithium transition metal phosphate compounds Some of the transition metal atoms of the main body are replaced by other elements such as Al, Ti, V, Cr, Mn, Fe, Co, Li, Ni, Cu, Zn, Mg, Ga, Zr, Nb, Si, etc.
  • a substance different from its composition may be attached to the surface of the positive electrode active material.
  • surface attachment substances may include, but are not limited to: oxides such as alumina, silica, titania, zirconia, magnesia, calcium oxide, boron oxide, antimony oxide, bismuth oxide; lithium sulfate, sodium sulfate, potassium sulfate , magnesium sulfate, calcium sulfate, aluminum sulfate and other sulfates; lithium carbonate, calcium carbonate, magnesium carbonate and other carbonates; carbon, etc.
  • a positive electrode active material having a composition different from the positive electrode active material attached to the surface of the positive electrode active material is also referred to as a "positive electrode active material".
  • the shape of the positive electrode active material particles includes, but is not limited to, block shape, polyhedron shape, spherical shape, ellipsoidal shape, plate shape, needle shape and columnar shape.
  • the positive active material particles include primary particles, secondary particles, or a combination thereof. In some embodiments, primary particles may agglomerate to form secondary particles.
  • positive electrode conductive material is not limited, and any known conductive material can be used.
  • positive electrode conductive materials may include, but are not limited to, graphite such as natural graphite and artificial graphite; carbon black such as acetylene black; carbon materials such as amorphous carbon such as needle coke; carbon nanotubes; graphene and the like.
  • the above positive electrode conductive materials can be used alone or in any combination.
  • positive electrode binder used in the production of the positive electrode active material layer is not particularly limited, and in the case of the coating method, any material can be dissolved or dispersed in the liquid medium used in electrode production.
  • positive electrode binders may include, but are not limited to, one or more of the following: polyethylene, polypropylene, polyethylene terephthalate, polymethyl methacrylate, polyimide, Aramid, cellulose, nitrocellulose and other resin-based polymers; styrene-butadiene rubber (SBR), nitrile rubber (NBR), fluororubber, isoprene rubber, polybutadiene rubber, ethylene-propylene rubber and other rubber Shaped polymer; styrene-butadiene-styrene block copolymer or its hydrogenated product, ethylene-propylene-diene terpolymer (EPDM), styrene-ethylene-butadiene-ethylene copolymer, benzene Thermoplastic
  • the kind of solvent used to form the positive electrode slurry is not limited as long as it is a solvent capable of dissolving or dispersing the positive electrode active material, conductive material, positive electrode binder, and thickener used as needed.
  • the solvent used to form the positive electrode slurry may include any one of aqueous solvents and organic solvents.
  • the aqueous medium may include, but are not limited to, water, a mixed medium of alcohol and water, and the like.
  • organic media may include, but are not limited to, aliphatic hydrocarbons such as hexane; aromatic hydrocarbons such as benzene, toluene, xylene, and methylnaphthalene; heterocyclic compounds such as quinoline and pyridine; acetone, methyl ethyl ketones such as ketone and cyclohexanone; esters such as methyl acetate and methyl acrylate; amines such as diethylenetriamine and N,N-dimethylaminopropylamine; diethyl ether, propylene oxide, tetrahydrofuran (THF ) and other ethers; amides such as N-methylpyrrolidone (NMP), dimethylformamide, and dimethylacetamide; aprotic polar solvents such as hexamethylphosphoramide and dimethyl sulfoxide, etc.
  • aliphatic hydrocarbons such as hexane
  • aromatic hydrocarbons such as benz
  • Thickeners are generally used to adjust the viscosity of the slurry.
  • thickeners and styrene-butadiene rubber (SBR) emulsions can be used for slurrying.
  • SBR styrene-butadiene rubber
  • the kind of thickener is not particularly limited, and examples thereof may include, but are not limited to, carboxymethylcellulose, methylcellulose, hydroxymethylcellulose, ethylcellulose, polyvinyl alcohol, oxidized starch, phosphorylated starch , casein and their salts, etc.
  • the above-mentioned thickeners can be used alone or in any combination.
  • the type of the positive electrode collector is not particularly limited, and it can be any known material suitable for use as the positive electrode collector.
  • the positive current collector may include, but are not limited to, metal materials such as aluminum, stainless steel, nickel plating, titanium, and tantalum; carbon materials such as carbon cloth and carbon paper.
  • the positive current collector is a metal material.
  • the positive current collector is aluminum.
  • the surface of the positive electrode current collector may include a conductive aid.
  • conductive aids may include, but are not limited to, carbon and noble metals such as gold, platinum, and silver.
  • the positive electrode can be produced by forming a positive electrode active material layer containing a positive electrode active material and a binder on a current collector.
  • the manufacture of the positive electrode using the positive electrode active material can be carried out by a conventional method, that is, the positive electrode active material and the binder, as well as the conductive material and thickener as required, etc. are dry mixed, made into a sheet, and the obtained The sheet is pressed onto the positive current collector; or these materials are dissolved or dispersed in a liquid medium to make a slurry, and the slurry is coated on the positive current collector and dried to form a positive electrode current collector.
  • a positive electrode active material layer whereby a positive electrode can be obtained.
  • the electrolytic solution used in the electrochemical device of the present application includes an electrolyte and a solvent for dissolving the electrolyte.
  • the electrolyte solution includes a difluorophosphite compound.
  • the difluorophosphite compound includes a compound of formula II:
  • A is substituted or unsubstituted C1-10 alkyl or C3-10 cycloalkyl
  • the substituent When substituted, the substituent is halogen or cyano.
  • the difluorophosphite compound includes ether linkages.
  • the difluorophosphite compound containing ether bonds can be better combined with poly(amic acid), so that when thermal runaway occurs, it can respond quickly and undergo polymerization reaction, further improving the float charge performance and safety of the electrochemical device.
  • the difluorophosphite compound includes at least one of the following compounds:
  • the content of the difluorophosphite compound is b%, and the value of b ranges from 0.1 to 5. In some embodiments, b ranges from 0.5 to 5. In some embodiments, x is 0.1, 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5 or within a range consisting of any two values above. When the content of the difluorophosphite compound in the electrolyte is within the above range, it is helpful to further improve the float charge performance and safety of the electrochemical device.
  • a and b satisfy: 0.1 ⁇ a/b ⁇ 5. In some embodiments, a and b satisfy: 0.2 ⁇ a/b ⁇ 2.5. In some embodiments, a and b satisfy: 0.5 ⁇ a/b ⁇ 2. In some embodiments, a and b satisfy: 1 ⁇ a/b ⁇ 1.5. In some embodiments, a/b is 0.1, 0.2, 0.5, 1, 2, 2.5, 3, 3.5, 4, 4.5, 5 or within a range consisting of any two values above.
  • the electrolyte solution further includes a compound containing a sulfur-oxygen double bond
  • the compound containing a sulfur-oxygen double bond includes at least one of the following compounds: cyclic sulfate, chain sulfate, chain Sulfonate, cyclic sulfonate, chain sulfite or cyclic sulfite or compound of formula III:
  • L is selected from a single bond or methylene
  • n is an integer from 1 to 4.
  • n is an integer from 0 to 2;
  • p is an integer of 0 to 6.
  • the compound of formula III is selected from at least one of the following:
  • the structural stability of the positive electrode active material under thermal runaway conditions can be further improved, and at the same time, it can accelerate the formation of poly(amic acid) and difluoride at high temperature.
  • the thermal polymerization reaction between the phosphite compounds can rapidly reduce the ion conductance and electron conductance, and further improve the float charge performance and safety of the electrochemical device.
  • the content of the difluorophosphite compound is b%, the content of the compound containing sulfur and oxygen double bonds is c%, and b and c satisfy: 1 ⁇ b+c ⁇ 8 and 0.4 ⁇ b/c ⁇ 5.
  • b+c is 1, 2, 3, 4, 5, 6, 7, 8 or within a range consisting of any two values above.
  • b/c is 0.4, 0.5, 1, 2, 3, 4, 5 or within a range consisting of any two values above.
  • the content of the sulfur-oxygen double bond-containing compound is c%, and the value of c ranges from 0.1 to 8. In some embodiments, c ranges from 0.1 to 5. In some embodiments, the value of c ranges from 0.1 to 3. In some embodiments, c ranges from 0.1 to 1.5. In some embodiments, c is 0.1, 0.3, 0.5, 1, 2, 2.5, 3, 3.5, 4, 4.5, 5, 8 or within a range consisting of any two of the above values.
  • the electrolyte solution further comprises any non-aqueous solvent known in the prior art as a solvent for the electrolyte solution.
  • the non-aqueous solvent includes, but is not limited to, one or more of the following: cyclic carbonate, chain carbonate, cyclic carboxylate, chain carboxylate, cyclic Ethers, chain ethers, phosphorus-containing organic solvents, sulfur-containing organic solvents, and aromatic fluorinated solvents.
  • examples of the cyclic carbonate may include, but are not limited to, one or more of the following: ethylene carbonate (EC), propylene carbonate (PC), and butylene carbonate.
  • the cyclic carbonate has 3-6 carbon atoms.
  • examples of the chain carbonate may include, but are not limited to, one or more of the following: dimethyl carbonate, ethyl methyl carbonate, diethyl carbonate (DEC), methyl carbonate Chain carbonates such as ethyl n-propyl carbonate, ethyl n-propyl carbonate, di-n-propyl carbonate, etc.
  • chain carbonates substituted with fluorine may include, but are not limited to, one or more of the following: bis(fluoromethyl)carbonate, bis(difluoromethyl)carbonate, bis(trifluoromethyl)carbonate base) carbonate, bis(2-fluoroethyl)carbonate, bis(2,2-difluoroethyl)carbonate, bis(2,2,2-trifluoroethyl)carbonate, 2-fluoroethyl methyl carbonate, 2,2-difluoroethyl methyl carbonate and 2,2,2-trifluoroethyl methyl carbonate, etc.
  • examples of the cyclic carboxylate may include, but are not limited to, one or more of the following: one or more of ⁇ -butyrolactone and ⁇ -valerolactone.
  • some of the hydrogen atoms of the cyclic carboxylate may be replaced by fluorine.
  • examples of the chain carboxylate may include, but are not limited to, one or more of the following: methyl acetate, ethyl acetate, propyl acetate, isopropyl acetate, butyl acetate ester, sec-butyl acetate, isobutyl acetate, tert-butyl acetate, methyl propionate, ethyl propionate, propyl propionate, isopropyl propionate, methyl butyrate, ethyl butyrate, butyric acid Propyl ester, methyl isobutyrate, ethyl isobutyrate, methyl valerate, ethyl valerate, methyl pivalate and ethyl pivalate, etc.
  • part of the hydrogen atoms of the chain carboxylate may be substituted by fluorine.
  • examples of fluorine-substituted chain carboxylic acid esters may include, but are not limited to, methyl trifluoroacetate, ethyl trifluoroacetate, propyl trifluoroacetate, butyl trifluoroacetate, and trifluoroacetic acid 2,2,2-trifluoroethyl ester, etc.
  • examples of the cyclic ether may include, but are not limited to, one or more of the following: tetrahydrofuran, 2-methyltetrahydrofuran, 1,3-dioxolane, 2-methyl 1,3-dioxolane, 4-methyl 1,3-dioxolane, 1,3-dioxane, 1,4-dioxane and dimethoxypropane.
  • examples of the chain ethers may include, but are not limited to, one or more of the following: dimethoxymethane, 1,1-dimethoxyethane, 1,2- Dimethoxyethane, diethoxymethane, 1,1-diethoxyethane, 1,2-diethoxyethane, ethoxymethoxymethane, 1,1-ethoxy Methoxyethane and 1,2-ethoxymethoxyethane, etc.
  • examples of the phosphorus-containing organic solvent may include, but are not limited to, one or more of the following: trimethyl phosphate, triethyl phosphate, dimethyl ethyl phosphate, methyl phosphate Diethyl ester, ethylene methyl phosphate, ethylene ethyl phosphate, triphenyl phosphate, trimethyl phosphite, triethyl phosphite, triphenyl phosphite, tris(2,2,2- phosphate Trifluoroethyl) ester and tris(2,2,3,3,3-pentafluoropropyl) phosphate, etc.
  • examples of the sulfur-containing organic solvent may include, but are not limited to, one or more of the following: sulfolane, 2-methylsulfolane, 3-methylsulfolane, dimethylsulfone, disulfone Ethyl sulfone, ethyl methyl sulfone, methyl propyl sulfone, dimethyl sulfoxide, methyl methanesulfonate, ethyl methanesulfonate, methyl ethanesulfonate, ethyl ethanesulfonate, dimethyl sulfate , diethyl sulfate and dibutyl sulfate.
  • some hydrogen atoms of the sulfur-containing organic solvent may be replaced by fluorine.
  • the aromatic fluorinated solvent includes, but is not limited to, one or more of the following: fluorobenzene, difluorobenzene, trifluorobenzene, tetrafluorobenzene, pentafluorobenzene, hexafluorobenzene and trifluoromethylbenzene.
  • the solvent used in the electrolyte of the present application includes cyclic carbonates, chain carbonates, cyclic carboxylates, chain carboxylates, and combinations thereof.
  • the solvent used in the electrolyte of the present application comprises an organic solvent selected from the group consisting of ethylene carbonate, propylene carbonate, diethyl carbonate, ethyl propionate, propionic acid Propyl ester, n-propyl acetate, ethyl acetate and combinations thereof.
  • the solvent used in the electrolyte of the present application comprises: ethylene carbonate, propylene carbonate, diethyl carbonate, ethyl propionate, propyl propionate, ⁇ -butyrolactone and combinations thereof .
  • the electrolyte is not particularly limited, and any known substance as an electrolyte can be used arbitrarily.
  • lithium salts are generally used.
  • electrolytes may include, but are not limited to, inorganic lithium salts such as LiPF 6 , LiBF 4 , LiClO 4 , LiAlF 4 , LiSbF 6 , LiWF 7 ; lithium tungstates such as LiWOF 5 ; HCO 2 Li, CH 3 CO 2 Li, CH 2 FCO 2 Li, CHF 2 CO 2 Li, CF 3 CO 2 Li, CF 3 CH 2 CO 2 Li, CF 3 CF 2 CO 2 Li, CF 3 CF 2 CO 2 Li, CF 3 CF 2 CF 2 CO 2 Li, CF 3 CF 2 CF 2 Lithium carboxylate salts such as CF 2 CO 2 Li; FSO 3 Li, CH 3 SO 3 Li, CH 2 FSO 3 Li, CHF 2 SO 3 Li, CF 3 SO 3 Li, CF 3 CF 2 SO 3 Li, CF 3
  • the electrolyte is selected from LiPF 6 , LiSbF 6 , FSO 3 Li, CF 3 SO 3 Li, LiN(FSO 2 ) 2 , LiN(FSO 2 )(CF 3 SO 2 ), LiN(CF 3 SO 2 ) 2 , LiN(C 2 F 5 SO 2 ) 2 , cyclic lithium 1,2-perfluoroethanebissulfonimide, cyclic lithium 1,3-perfluoropropanebissulfonimide, LiC(FSO 2 ) 3 , LiC(CF 3 SO 2 ) 3 , LiC(C 2 F 5 SO 2 ) 3 , LiBF 3 CF 3 , LiBF 3 C 2 F 5 , LiPF 3 (CF 3 ) 3 , LiPF 3 (C 2 F 5 ) 3.
  • Lithium difluorooxalate borate, lithium bis(oxalate)borate or lithium difluorobis(oxalato)phosphate which help to improve the output power characteristics, high-rate charge and discharge characteristics, and high-temperature storage characteristics of electrochemical devices and cycle characteristics, etc.
  • the content of the electrolyte is not particularly limited as long as the effect of the present application is not impaired.
  • the total molar concentration of lithium in the electrolyte is greater than 0.3 mol/L, greater than 0.4 mol/L or greater than 0.5 mol/L.
  • the total molar concentration of lithium in the electrolyte is less than 3 mol/L, less than 2.5 mol/L or less than 2.0 mol/L.
  • the total molar concentration of lithium in the electrolyte is within the range formed by any two values above. When the electrolyte concentration is within the above range, the lithium as charged particles will not be too small, and the viscosity can be kept in an appropriate range, so it is easy to ensure good electrical conductivity.
  • the electrolyte includes at least one salt selected from the group consisting of monofluorophosphate, borate, oxalate, and fluorosulfonate.
  • the electrolyte includes a salt selected from the group consisting of monofluorophosphate, oxalate, and fluorosulfonate.
  • the electrolyte includes a lithium salt.
  • the salt selected from the group consisting of monofluorophosphate, borate, oxalate, and fluorosulfonate is present at greater than 0.01% or greater than 0.1% by weight of the electrolyte.
  • the salt selected from the group consisting of monofluorophosphate, borate, oxalate, and fluorosulfonate comprises less than 20% or less than 10% by weight of the electrolyte. In some embodiments, the content of the salt selected from the group consisting of monofluorophosphate, borate, oxalate and fluorosulfonate is within the range formed by any two of the above values.
  • the electrolyte includes one or more substances selected from the group consisting of monofluorophosphate, borate, oxalate, and fluorosulfonate and one or more salts other than these.
  • Other salts include the lithium salts exemplified above, and in some examples, LiPF 6 , LiN(FSO 2 )(CF 3 SO 2 ), LiN(CF 3 SO 2 ) 2 , LiN( C 2 F 5 SO 2 ) 2 , cyclic lithium 1,2-perfluoroethanebissulfonimide, cyclic lithium 1,3-perfluoropropanebissulfonimide, LiC(FSO 2 ) 3 , LiC (CF 3 SO 2 ) 3 , LiC(C 2 F 5 SO 2 ) 3 , LiBF 3 CF 3 , LiBF 3 C 2 F 5 , LiPF 3 (CF 3 ) 3 , LiPF 3 (C 2 F 5 ) 3 .
  • the additional salt is LiPF 6
  • the additional salts are present at greater than 0.01% or greater than 0.1% by weight of the electrolyte. In some embodiments, the additional salts are present at less than 20%, less than 15%, or less than 10% by weight of the electrolyte. In some embodiments, the content of other salts is within the range formed by any two values above. Salts other than these having the above content contribute to the balance of the electrical conductivity and viscosity of the electrolytic solution.
  • the negative electrode includes a negative electrode current collector and a positive electrode active material layer disposed on one or both surfaces of the negative electrode current collector, and the negative electrode active material layer contains the negative electrode active material.
  • the negative electrode active material layer may be one or more layers, and each layer of the multilayer negative electrode active material may contain the same or different negative electrode active materials.
  • the negative electrode active material is any material capable of reversibly intercalating and deintercalating metal ions such as lithium ions.
  • the chargeable capacity of the negative active material is greater than the discharge capacity of the positive active material, so as to prevent unintentional precipitation of lithium metal on the negative electrode during charging.
  • any known current collector can be used arbitrarily.
  • negative electrode current collectors include, but are not limited to, metal materials such as aluminum, copper, nickel, stainless steel, and nickel-plated steel. In some embodiments, the negative current collector is copper.
  • the form of the negative electrode current collector may include, but not limited to, metal foil, metal cylinder, metal strip, metal plate, metal film, expanded metal, stamped metal, foamed metal, etc.
  • the negative electrode current collector is a metal film.
  • the negative electrode current collector is copper foil.
  • the negative electrode current collector is a rolled copper foil based on a rolling method or an electrolytic copper foil based on an electrolytic method.
  • the thickness of the negative electrode current collector is greater than 1 ⁇ m or greater than 5 ⁇ m. In some embodiments, the thickness of the negative electrode current collector is less than 100 ⁇ m or less than 50 ⁇ m. In some embodiments, the thickness of the negative electrode current collector is within the range formed by any two values above.
  • the negative electrode active material is not particularly limited as long as it can reversibly store and release lithium ions.
  • Examples of negative electrode active materials may include, but are not limited to, carbon materials such as natural graphite and artificial graphite; metals such as silicon (Si) and tin (Sn); or oxides of metal elements such as Si and Sn.
  • the negative electrode active materials can be used alone or in combination.
  • the negative active material layer may further include a negative binder.
  • the negative electrode binder can improve the combination of the negative electrode active material particles and the combination of the negative electrode active material and the current collector.
  • the type of negative electrode binder is not particularly limited, as long as it is a material stable to the electrolyte solution or the solvent used in electrode production.
  • the negative binder includes a resin binder.
  • resin binders include, but are not limited to, fluororesins, polyacrylonitrile (PAN), polyimide resins, acrylic resins, polyolefin resins, and the like.
  • the negative electrode binder When using a water-based solvent to prepare the negative electrode mixture slurry, the negative electrode binder includes, but is not limited to, carboxymethyl cellulose (CMC) or its salt, styrene-butadiene rubber (SBR), polyacrylic acid (PAA) or Its salt, polyvinyl alcohol, etc.
  • CMC carboxymethyl cellulose
  • SBR styrene-butadiene rubber
  • PAA polyacrylic acid
  • Its salt polyvinyl alcohol, etc.
  • the negative electrode can be prepared by the following method: coating the negative electrode mixture slurry comprising negative electrode active material, resin binder, etc. on the negative electrode current collector, after drying, calendering to form negative electrode active material layers on both sides of the negative electrode current collector, thus Negative pole is available.
  • a separator is usually provided between the positive electrode and the negative electrode.
  • the electrolytic solution of the present application is usually used by permeating the separator.
  • the material and shape of the separator are not particularly limited as long as the effect of the present application is not significantly impaired.
  • the separator can be resin, glass fiber, inorganic material, etc. formed of materials stable to the electrolyte solution of the present application.
  • the separator includes a porous sheet or a non-woven fabric-like substance with excellent liquid retention properties.
  • the material of the resin or fiberglass separator may include, but are not limited to, polyolefin, aramid, polytetrafluoroethylene, polyethersulfone, and the like.
  • the polyolefin is polyethylene or polypropylene.
  • the polyolefin is polypropylene.
  • the materials for the above separators may be used alone or in any combination.
  • the isolation film can also be a material formed by laminating the above materials, examples of which include, but not limited to, a three-layer isolation film formed by laminating polypropylene, polyethylene, and polypropylene in this order.
  • Examples of materials of inorganic substances may include, but are not limited to, oxides such as aluminum oxide and silicon dioxide, nitrides such as aluminum nitride and silicon nitride, sulfates (eg, barium sulfate, calcium sulfate, etc.).
  • Inorganic forms may include, but are not limited to, granular or fibrous.
  • the form of the separator may be in the form of a film, examples of which include, but are not limited to, non-woven fabrics, woven fabrics, microporous films, and the like.
  • the pore diameter of the isolation membrane is 0.01 ⁇ m to 1 ⁇ m, and the thickness is 5 ⁇ m to 50 ⁇ m.
  • the following separator can also be used: a separator formed by forming a composite porous layer containing the above-mentioned inorganic particles on the surface of the positive electrode and/or negative electrode using a resin-based binder,
  • a separator is formed by using a fluororesin as a binder to form porous layers on both sides of the positive electrode with 90% of the alumina particles having a particle size of less than 1 ⁇ m.
  • the thickness of the separator is arbitrary. In some embodiments, the thickness of the isolation film is greater than 1 ⁇ m, greater than 5 ⁇ m, or greater than 8 ⁇ m. In some embodiments, the thickness of the isolation film is less than 50 ⁇ m, less than 40 ⁇ m or less than 30 ⁇ m. In some embodiments, the thickness of the isolation film is within the range formed by any two values above. When the thickness of the separator is within the above range, insulation and mechanical strength can be ensured, and rate characteristics and energy density of the electrochemical device can be ensured.
  • the porosity of the separator is arbitrary.
  • the isolation membrane has a porosity greater than 10%, greater than 15%, or greater than 20%.
  • the separator has a porosity of less than 60%, less than 50%, or less than 45%.
  • the porosity of the isolation membrane is within the range formed by any two values above. When the porosity of the separator is within the above range, insulation and mechanical strength can be ensured, and membrane resistance can be suppressed, so that the electrochemical device has good safety characteristics.
  • the average pore diameter of the separator is also arbitrary. In some embodiments, the average pore size of the isolation membrane is less than 0.5 ⁇ m or less than 0.2 ⁇ m. In some embodiments, the average pore size of the isolation membrane is greater than 0.05 ⁇ m. In some embodiments, the average pore diameter of the isolation membrane is within the range formed by any two values above. When the average pore diameter of the separator exceeds the above-mentioned range, short circuits are likely to occur. When the average pore diameter of the isolation membrane is within the above range, the electrochemical device has good safety characteristics.
  • the electrochemical device assembly includes an electrode group, a current collecting structure, an outer casing and a protection element.
  • the electrode group may have either a laminated structure in which the positive electrode and the negative electrode are laminated with the separator interposed therebetween, or a structure in which the positive electrode and the negative electrode are wound in a spiral shape with the separator interposed therebetween.
  • the ratio of the mass of the electrode group to the internal volume of the battery is greater than 40% or greater than 50%.
  • the electrode set occupancy is less than 90% or less than 80%.
  • the occupancy of the electrode group is within the range formed by any two values above. When the electrode group occupancy ratio is within the above range, the capacity of the electrochemical device can be ensured, and at the same time, the decrease in characteristics such as repeated charge-discharge performance and high-temperature storage due to an increase in internal pressure can be suppressed.
  • the current collecting structure is not particularly limited. In some embodiments, the current collecting structure is a structure that reduces the resistance of the wiring portion and the bonding portion.
  • the electrode group has the above-mentioned laminated structure, it is suitable to use a structure in which the metal core portions of the electrode layers are bundled and welded to the terminal.
  • the internal resistance increases, so it is also suitable to provide two or more terminals in the electrode to reduce the resistance.
  • the electrode group has the above-mentioned winding structure, the internal resistance can be reduced by providing two or more lead wire structures on the positive electrode and the negative electrode respectively, and bundling them on the terminals.
  • the material of the outer case is not particularly limited, as long as it is stable to the electrolyte solution used.
  • metals such as nickel-plated steel sheets, stainless steel, aluminum or aluminum alloys, and magnesium alloys, or laminated films of resin and aluminum foil can be used, but not limited to.
  • the outer casing is aluminum or aluminum alloy metal or a laminated film.
  • Metal exterior cases include, but are not limited to, encapsulation and sealing structures formed by welding metals together by laser welding, resistance welding, or ultrasonic welding; or riveted structures using the above-mentioned metals through resin spacers.
  • the exterior case using the above-mentioned laminated film includes, but is not limited to, a package sealing structure formed by thermally bonding resin layers to each other, and the like. In order to improve the sealability, a resin different from the resin used in the laminated film may be interposed between the above-mentioned resin layers.
  • a resin having a polar group or a modified resin into which a polar group is introduced can be used as the interposed resin due to the bonding between the metal and the resin.
  • the shape of the exterior body is also arbitrary, and for example, any of cylindrical, square, laminated, button-shaped, large, and the like may be used.
  • Protection elements can use positive temperature coefficient (PTC) whose resistance increases when abnormal heat generation or excessive current flows, temperature fuses, thermistors, cut off by causing the internal pressure of the battery or the internal temperature to rise sharply at the time of abnormal heat generation A valve (current cut-off valve) for the current flowing in the circuit, etc.
  • PTC positive temperature coefficient
  • the above-mentioned protection elements can be selected under the condition that they do not work in the normal use of high current, and can also be designed in such a way that abnormal heat dissipation or thermal runaway will not occur even if there is no protection element.
  • the electrochemical device of the present application includes any device that undergoes an electrochemical reaction, and specific examples thereof include a lithium metal secondary battery or a lithium ion secondary battery.
  • the present application further provides an electronic device, which includes the electrochemical device according to the present application.
  • the application of the electrochemical device of the present application is not particularly limited, and it can be used in any electronic device known in the prior art.
  • the electrochemical device of the present application can be used in, but not limited to, notebook computers, pen-based computers, mobile computers, e-book players, portable phones, portable fax machines, portable copiers, portable printers, head-worn Stereo headphones, VCRs, LCD TVs, portable cleaners, portable CD players, mini discs, transceivers, electronic organizers, calculators, memory cards, portable tape recorders, radios, backup power supplies, motors, automobiles, motorcycles, power assist Bicycles, bicycles, lighting equipment, toys, game consoles, clocks, electric tools, flashlights, cameras, large household storage batteries and lithium-ion capacitors, etc.
  • the lithium ion battery is taken as an example below and the preparation of the lithium ion battery is described in conjunction with specific examples. Those skilled in the art will understand that the preparation method described in this application is only an example, and any other suitable preparation methods are described in this application. within range.
  • the positive electrode slurry was coated on a 12 ⁇ m aluminum foil, dried, cold pressed, cut into pieces, and tabs were welded to obtain a positive electrode.
  • a polyethylene porous polymer film is used as a separator.
  • the electrolyte solution is poured from the liquid injection port, packaged, and then the lithium-ion battery is produced through processes such as formation and capacity.
  • the lithium-ion battery was then short-circuited at 100 m ⁇ for 10 seconds, and then the thickness T 2 of the lithium-ion battery was measured.
  • the high-temperature short-circuit deformation rate of lithium-ion batteries is calculated by the following formula:
  • Short-circuit deformation rate [(T 2 -T 1 )/T 1 ] ⁇ 100%.
  • Overcharge deformation rate [(H 2 -H 1 )/H 1 ] ⁇ 100%.
  • the Li-ion battery was charged at a constant current of 0.5C to 4.7V, and then charged at a constant voltage of 4.7V to 0.05C. Then, the lithium-ion battery was placed in an oven at 50° C., continuously charged at a constant voltage of 4.7 V (the cut-off current was 20 mA), and the thickness change of the lithium-ion battery was monitored. Taking the thickness of the lithium-ion battery at the initial 50% state of charge (SOC) as a benchmark, when the thickness of the lithium-ion battery increases by more than 20%, it is recorded as failure. Record the time from float charge to failure of the lithium-ion battery at 50°C, in hours (h) as the statistical unit.
  • SOC state of charge
  • Table 1 shows the impact of the positive electrode active material and electrolyte on the float performance and safety of the lithium-ion battery, wherein the difluorophosphite compound is the compound of formula II-1.
  • Comparative Example 1-1 although the electrolyte includes a difluorophosphite compound, but the positive electrode active material does not include poly(amic acid), the overcharge deformation rate and short circuit deformation rate of the lithium-ion battery are high and the float charge fails. The time is shorter. As shown in Comparative Examples 1-2, although the positive electrode active material includes poly(amic acid), but the electrolyte does not include difluorophosphite compounds, the overcharge deformation rate and short circuit deformation rate of the lithium ion battery are high and the float charge failure The time is shorter.
  • the overcharge deformation rate and short circuit deformation rate of the lithium-ion battery can be significantly reduced And significantly improve its floating charge failure time.
  • Poly(amic acid)s of different structures can achieve substantially equivalent effects.
  • the overcharge of the lithium-ion battery can be further reduced Deformation rate and short-circuit deformation rate and increase its floating charge failure time.
  • the content of poly(amic acid) in the positive electrode active material layer is in the range of 0.5%-5%, it can further reduce the overcharge deformation rate and short circuit deformation rate of the lithium ion battery and improve its floating charge failure time.
  • the overcharge deformation rate and short circuit deformation rate of the lithium ion battery can be further reduced and the floating charge failure time can be improved.
  • Table 2 shows the effect of difluorophosphite compounds with different structures on the float performance and safety of lithium-ion batteries. Except for the parameters listed in Table 2, the settings of Examples 2-1 to 2-8 are the same as those of Example 1-1.
  • Example 1-1 Formula II-1 16.9 17.8 805
  • Example 2-1 Formula II-2 15.3 16.4 835
  • Example 2-2 Formula II-3 15.2 16.5 842
  • Example 2-3 Formula II-4 15.3 16.2 879
  • Example 2-4 Formula II-5 12.3 12.6 1006
  • Example 2-5 Formula II-6 11.6 11.9 1021
  • Example 2-6 Formula II-7 13.7 12.5 978
  • Example 2-7 Formula II-8 13.2 12.1 993
  • Example 2-8 Formula II-9 12.6 11.8 1068
  • difluorophosphite compounds with different structures can achieve substantially equivalent effects.
  • ether bond embdiment 2-4, 2-5 and 2-8 in the difluorophosphite compound, can further reduce the overcharge deformation rate and the short circuit deformation rate of lithium-ion battery and improve its floating charge failure time .
  • Table 3 shows the influence of the sulfur-oxygen double bond compound on the float performance and safety of the lithium-ion battery, wherein the content of the sulfur-oxygen double bond compound in the electrolyte is 1%. Except for the parameters listed in Table 3, the settings of Examples 3-1 to 3-5 are the same as those of Example 1-1.
  • Example 1-1 16.9 17.8 805
  • Example 3-2 DTD 13.2 14.2
  • Example 3-3 Formula III-1 13.7 14.8 823
  • Example 3-4 Formula III-3 11.5 11.9 895
  • Example 3-5 Formula III-4 11.2 10.5 1124
  • Table 4 shows the effect of the content relationship between the difluorophosphite compound and the sulfur-oxygen double bond compound in the electrolyte on the float performance and safety of the lithium-ion battery. Except for the parameters listed in Table 4, the settings of Examples 4-1 to 4-9 are the same as those of Example 1-1.
  • references to “embodiment”, “partial embodiment”, “an embodiment”, “another example”, “example”, “specific example” or “partial example” in the entire specification mean that At least one embodiment or example in the present application includes a specific feature, structure, material or characteristic described in the embodiment or example.
  • descriptions that appear throughout the specification such as: “in some embodiments”, “in an embodiment”, “in one embodiment”, “in another example”, “in an example In”, “in a particular example” or “example”, they are not necessarily referring to the same embodiment or example in this application.
  • the particular features, structures, materials, or characteristics herein may be combined in any suitable manner in one or more embodiments or examples.

Abstract

本申请涉及一种电化学装置和电子装置。具体而言，本申请提供一种电化学装置，其包括：正极、负极和电解液，所述正极包括正极集流体和形成在所述正极集流体上的正极活性物质层，其中：所述正极活性物质层包括聚(酰胺酸)，并且所述电解液包括二氟亚磷酸酯化合物。本申请的电化学装置具有改善的浮充性能和安全性。

Description

电化学装置和电子装置 技术领域
本申请涉及储能领域，具体涉及一种电化学装置和电子装置，特别是锂离子电池。
背景技术
近年来，随着智能手机、平板电脑和智能穿戴等电子产品的快速发展，考虑到电子产品的使用时长和工作环境的不同，人们对电化学装置(例如，锂离子电池)的性能提出了更高的要求，这体现在：较高的容量、合适的循环寿命、良好的高温性能、良好的高倍率放电性能、抗过充性能、浮充性能和安全性等。
虽然电池生产企业、原料供应商和科研院所围绕锂离子电池的性能改善做了大量工作，但现有方法仍然无法有效地提高锂离子电池的浮充性能并从根本上控制锂离子电池的热失控。
有鉴于此，确有必要提供一种具有改进的浮充性能和安全性的电化学装置和电子装置。
发明内容
本申请实施例通过提供一种具有改善的浮充性能和安全性的电化学装置和电子装置以在某种程度上解决存在于现有技术的问题。
在本申请的一方面，本申请提供一种电化学装置，其包括：正极、负极和电解液，所述正极包括正极集流体和形成在所述正极集流体上的正极活性物质层，其中：所述正极活性物质层包括聚(酰胺酸)，并且所述电解液包括二氟亚磷酸酯化合物。
根据本申请的实施例，基于所述正极活性物质层的重量，所述聚(酰胺酸)的含量为a％；基于所述电解液的重量，所述二氟亚磷酸酯化合物的含量为b％；且a和b满足：0.1≤a/b≤5。
根据本申请的实施例，a的取值范围为0.5至5。
根据本申请的实施例，b的取值范围为0.1至5。
根据本申请的实施例，所述聚(酰胺酸)包括式I化合物：
Figure PCTCN2021142400-appb-000001
其中：
R选自C1-12烯基或C6-12芳环；
A选自单键、C1-12烯基或C6-12芳环；
n为5至20的整数。
根据本申请的实施例，所述二氟亚磷酸酯化合物包括式II化合物：
A-OPF 2(式II)，
其中A为经取代或未经取代的C1-10烷基或C3-10环烷基；
经取代时，取代基为卤素或氰基。
根据本申请的实施例，所述二氟亚磷酸酯化合物包括以下化合物中的至少一种：
Figure PCTCN2021142400-appb-000002
Figure PCTCN2021142400-appb-000003
根据本申请的实施例，所述电解液还包括含硫氧双键的化合物，所述含硫氧双键的化合物包括以下化合物中的至少一者：环状硫酸酯、链状硫酸酯、链状磺酸酯、环状磺酸酯、链状亚硫酸酯或环状亚硫酸酯或式III化合物：
Figure PCTCN2021142400-appb-000004
其中：
W选自
Figure PCTCN2021142400-appb-000005
L选自单键或亚甲基；
m为1至4的整数；
n为0至2的整数；且
p为0至6的整数。
根据本申请的实施例，所述式III化合物选自以下中的至少一种：
Figure PCTCN2021142400-appb-000006
Figure PCTCN2021142400-appb-000007
根据本申请的实施例，基于所述电解液的重量，所述二氟亚磷酸酯化合物的含量为b％，所述含硫氧双键的化合物的含量为c％，b和c满足：1≤b+c≤8和0.4≤b/c≤5。
根据本申请的实施例，基于所述电解液的重量，所述含硫氧双键的化合物的含量为c％，c的取值范围为0.1至8。
根据本申请的实施例，c的取值范围为0.1至1.5
在本申请的另一方面，本申请提供一种电子装置，其包括根据本申请的电化学装置。
本申请使用的包括聚(酰胺酸)的正极活性物质和包括二氟亚磷酸酯化合物的电解液的特定组合可改善正极活性物质层在热失控下的的界面稳定性，并且能够充分抑制电化学装置在高压高温下的浮充厚度增长，有效防止电池热失控引起的燃烧或***等安全问题。
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。
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。
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”意味着仅A；仅B；或A及B。在另一实例中，如果列出项目A、B及C，那么短语“A、B及C中的至少一者”意味着仅A；或仅B；仅C；A及B(排除C)；A及C(排除B)；B及C(排除A)；或A、B及C的全 部。项目A可包含单个元件或多个元件。项目B可包含单个元件或多个元件。项目C可包含单个元件或多个元件。术语“中的至少一种”具有与术语“中的至少一者”相同的含义。
术语“烷基”预期是具有1至20个碳原子的直链饱和烃结构。“烷基”还预期是具有3至20个碳原子的支链或环状烃结构。当指定具有具体碳数的烷基时，预期涵盖具有该碳数的所有几何异构体；因此，例如，“丁基”意思是包括正丁基、仲丁基、异丁基、叔丁基和环丁基；“丙基”包括正丙基、异丙基和环丙基。烷基实例包括，但不限于甲基、乙基、正丙基、异丙基、环丙基、正丁基、异丁基、仲丁基、叔丁基、环丁基、正戊基、异戊基、新戊基、环戊基、甲基环戊基、乙基环戊基、正己基、异己基、环己基、正庚基、辛基、环丙基、环丁基、降冰片基等。
术语“烯基”是指可为直链或具支链且具有至少一个且通常1个、2个或3个碳碳双键的单价不饱和烃基团。除非另有定义，否则所述烯基通常含有2个到20个碳原子且包括(例如)-C 2-4烯基、-C 2-6烯基及-C 2-10烯基。代表性烯基包括(例如)乙烯基、正丙烯基、异丙烯基、正-丁-2-烯基、丁-3-烯基、正-己-3-烯基等。
术语“芳环”意指具有单环(例如，苯基)或稠合环的单价芳香族烃。稠合环***包括那些完全不饱和的环***(例如，萘)以及那些部分不饱和的环***(例如，1,2,3,4-四氢萘)。除非另有定义，否则所述芳环通常含有6个到26个碳环原子且包括(例如)-C 6-10芳基。代表性芳基包括(例如)苯基、甲基苯基、丙基苯基、异丙基苯基、苯甲基和萘-1-基、萘-2-基等等。
术语“环烷基”涵盖环状烷基。环烷基可为3-20个碳原子的环烷基、6-20个碳原子的环烷基、3-12个碳原子的环烷基、3-6个碳原子的环烷基。例如，环烷基可为环丙基、环丁基、环戊基、环己基等。另外，环烷基可以是任选地被取代的。
术语“卤素”指的是化学元素周期表中第ⅦA族元素，包括氟(F)、氯(Cl)、溴(Br)、碘(I)和砹(At)。
在保持正极和负极材料不变的前提下，改善电化学装置(例如，锂离子电池)的安全性的途径主要包括：在电解液内添加阻燃添加剂；和采用热闭孔隔膜或功能涂敷隔膜。然而，在实际应用过程中，将阻燃添加剂直接加入到电解液中会对 锂离子电池的电化学性能造成严重的不利影响。采用热闭孔隔膜或功能涂敷隔膜虽然能够提升锂离子电池的安全性，对于电池正常工作时的电化学性能影响较小，但依然无法从根本上控制电池热失控速率。
本申请通过使用包括聚(酰胺酸)的正极活性物质和包括二氟亚磷酸酯化合物的电解液的组合解决了上述问题。聚(酰胺酸)可以在160℃以上的温度下可转化为聚酰亚胺。在热失控发生温升较快的情况下，正极活性物质层中的聚(酰胺酸)可以快速吸收热量，发生聚合反应，生成具有绝缘功能的聚酰亚胺，从而阻隔正极活性物质的离子和电子传输，快速且有效地提升锂离子电池的安全性。然而，在常温下，聚(酰胺酸)会影响锂离子电池的浮充性能。在电解液中添加二氟亚磷酸酯化合物有助于改善锂离子电池的浮充性能，这是因为聚(酰胺酸)和二氟亚磷酸酯化合物之间存在大量的分子间作用力，从而减轻了常温下聚(酰胺酸)对锂离子的传输中离子电导的影响。此外，在高温高压下，聚(酰胺酸)和二氟亚磷酸酯化合物可形成复合聚合物，其对于改善锂离子电池的浮充性能和安全性的改善更为有效。因此，本申请的正极活性物质和电解液的特定组合可显著改善电化学装置的浮充性能和安全性。
I、正极
正极包括正极集流体和形成在所述正极集流体上的正极活性物质层。正极活性物质层可以是一层或多层。正极活性物质层包括正极活性物质，多层正极活性物质中的每层可以包含相同或不同的正极活性物质。
本申请的电化学装置的一个主要特征在于所述正极活性物质层包括聚(酰胺酸)。
在一些实施例中，所述聚(酰胺酸)包括式I化合物：
Figure PCTCN2021142400-appb-000008
其中：
R选自C1-12烯基或C6-12芳环；
A选自单键、C1-12烯基或C6-12芳环；
n为5至20的整数。
在一些实施例中，所述聚(酰胺酸)包括式I-1化合物(BPDA/PDA PAA)：
Figure PCTCN2021142400-appb-000009
其中n为5至20的整数。
在一些实施例中，基于所述正极活性物质层的重量，所述聚(酰胺酸)的含量为a％，a的取值范围为0.5至5。在一些实施例中，a的取值范围为1至3。在一些实施例中，x为0.5、1、2、2.5、3、3.5、4、4.5、5或在由上述任意两个数值所组成的范围内。当正极活性物质层中聚(酰胺酸)的含量在上述范围内时，有助于进一步提升电化学装置的浮充性能和安全性。
正极活性物质的种类没有特别限制，只要是能够以电化学方式吸藏和释放金属离子(例如，锂离子)即可。在一些实施例中，正极活性物质为含有锂和至少一种过渡金属的物质。正极活性物质的实例可包括，但不限于，锂过渡金属复合氧化物和含锂过渡金属磷酸化合物。
在一些实施例中，锂过渡金属复合氧化物中的过渡金属包括V、Ti、Cr、Mn、Fe、Co、Ni、Cu等。在一些实施例中，锂过渡金属复合氧化物包括LiCoO 2等锂钴复合氧化物、LiNiO 2等锂镍复合氧化物、LiMnO 2、LiMn 2O 4、Li 2MnO 4等锂锰复合氧化物、LiNi 1/3Mn 1/3Co 1/3O 2、LiNi 0.5Mn 0.3Co 0.2O 2等锂镍锰钴复合氧化物，其中作为这些锂过渡金属复合氧化物的主体的过渡金属原子的一部分被Na、K、B、F、Al、Ti、V、Cr、Mn、Fe、Co、Li、Ni、Cu、Zn、Mg、Ga、Zr、Si、Nb、Mo、Sn、W等其它元素所取代。锂过渡金属复合氧化物的实例可包括，但不限于，LiNi 0.5Mn 0.5O 2、LiNi 0.85Co 0.10Al 0.05O 2、LiNi 0.33Co 0.33Mn 0.33O 2、LiNi 0.45Co 0.10Al 0.45O 2、LiMn 1.8Al 0.2O 4和LiMn 1.5Ni 0.5O 4等。锂过渡金属复合氧化物的组合的实例包括，但不限于，LiCoO 2与LiMn 2O 4的组合，其中LiMn 2O 4中的一部分Mn可被过渡金属所取代(例如，LiNi 0.33Co 0.33Mn 0.33O 2)，LiCoO 2中的一部分Co可被过渡金属所取代。
在一些实施例中，含锂过渡金属磷酸化合物中的过渡金属包括V、Ti、Cr、 Mn、Fe、Co、Ni、Cu等。在一些实施例中，含锂过渡金属磷酸化合物包括LiFePO 4、Li 3Fe 2(PO 4) 3、LiFeP 2O 7等磷酸铁类、LiCoPO 4等磷酸钴类，其中作为这些锂过渡金属磷酸化合物的主体的过渡金属原子的一部分被Al、Ti、V、Cr、Mn、Fe、Co、Li、Ni、Cu、Zn、Mg、Ga、Zr、Nb、Si等其它元素所取代。
在一些实施例中，在上述正极活性物质的表面可附着有与其组成不同的物质。表面附着物质的实例可包括，但不限于：氧化铝、二氧化硅、二氧化钛、氧化锆、氧化镁、氧化钙、氧化硼、氧化锑、氧化铋等氧化物；硫酸锂、硫酸钠、硫酸钾、硫酸镁、硫酸钙、硫酸铝等硫酸盐；碳酸锂、碳酸钙、碳酸镁等碳酸盐；碳等。通过在正极活性物质表面附着物质，可以抑制正极活性物质表面的电解液的氧化反应，可以提高电化学装置的寿命。当表面附着物质的量过少时，其效果无法充分表现；当表面附着物质的量过多时，会阻碍锂离子的出入，因而电阻有时会增加。本申请中，将在正极活性物质的表面附着有与其组成不同的物质的正极活性物质也称为“正极活性物质”。
在一些实施例中，正极活性物质颗粒的形状包括，但不限于，块状、多面体状、球状、椭圆球状、板状、针状和柱状等。在一些实施例中，正极活性物质颗粒包括一次颗粒、二次颗粒或其组合。在一些实施例中，一次颗粒可以凝集而形成二次颗粒。
正极导电材料的种类没有限制，可以使用任何已知的导电材料。正极导电材料的实例可包括，但不限于，天然石墨、人造石墨等石墨；乙炔黑等炭黑；针状焦等无定形碳等碳材料；碳纳米管；石墨烯等。上述正极导电材料可单独使用或任意组合使用。
正极活性物质层的制造中使用的正极粘合剂的种类没有特别限制，在涂布法的情况下，只要是在电极制造时使用的液体介质中可溶解或分散的材料即可。正极粘合剂的实例可包括，但不限于，以下中的一种或多种：聚乙烯、聚丙烯、聚对苯二甲酸乙二醇酯、聚甲基丙烯酸甲酯、聚酰亚胺、芳香族聚酰胺、纤维素、硝酸纤维素等树脂系高分子；丁苯橡胶(SBR)、丁腈橡胶(NBR)、氟橡胶、异戊二烯橡胶、聚丁橡胶、乙烯-丙烯橡胶等橡胶状高分子；苯乙烯·丁二烯·苯乙烯嵌段共聚物或其氢化物、乙烯·丙烯·二烯三元共聚物(EPDM)、苯乙烯·乙烯·丁二烯·乙烯共聚物、苯乙烯·异戊二烯·苯乙烯嵌段共聚物或其氢化物等热塑性弹性体状高分子；间规-1,2-聚丁二烯、聚乙酸乙烯酯、乙烯·乙酸乙烯酯共聚物、丙 烯·α-烯烃共聚物等软质树脂状高分子；聚偏二氟乙烯(PVDF)、聚四氟乙烯、氟化聚偏二氟乙烯、聚四氟乙烯·乙烯共聚物等氟系高分子；具有碱金属离子(特别是锂离子)的离子传导性的高分子组合物等。上述正极粘合剂可单独使用或任意组合使用。
用于形成正极浆料的溶剂的种类没有限制，只要是能够溶解或分散正极活性物质、导电材料、正极粘合剂和根据需要使用的增稠剂的溶剂即可。用于形成正极浆料的溶剂的实例可包括水系溶剂和有机系溶剂中的任一种。水系介质的实例可包括，但不限于，水和醇与水的混合介质等。有机系介质的实例可包括，但不限于，己烷等脂肪族烃类；苯、甲苯、二甲苯、甲基萘等芳香族烃类；喹啉、吡啶等杂环化合物；丙酮、甲基乙基酮、环己酮等酮类；乙酸甲酯、丙烯酸甲酯等酯类；二亚乙基三胺、N,N-二甲氨基丙胺等胺类；二***、环氧丙烷、四氢呋喃(THF)等醚类；N-甲基吡咯烷酮(NMP)、二甲基甲酰胺、二甲基乙酰胺等酰胺类；六甲基磷酰胺、二甲基亚砜等非质子性极性溶剂等。
增稠剂通常是为了调节浆料的粘度而使用的。在使用水系介质的情况下，可使用增稠剂和丁苯橡胶(SBR)乳液进行浆料化。增稠剂的种类没有特别限制，其实例可包括，但不限于，羧甲基纤维素、甲基纤维素、羟甲基纤维素、乙基纤维素、聚乙烯醇、氧化淀粉、磷酸化淀粉、酪蛋白和它们的盐等。上述增稠剂可单独使用或任意组合使用。
正极集流体的种类没有特别限制，其可为任何已知适于用作正极集流体的材质。正极集流体的实例可包括，但不限于，铝、不锈钢、镍镀层、钛、钽等金属材料；碳布、碳纸等碳材料。在一些实施例中，正极集流体为金属材料。在一些实施例中，正极集流体为铝。
为了降低正极集流体和正极活性物质层的电子接触电阻，正极集流体的表面可包括导电助剂。导电助剂的实例可包括，但不限于，碳和金、铂、银等贵金属类。
正极可以通过在集流体上形成含有正极活性物质和粘结剂的正极活性物质层来制作。使用正极活性物质的正极的制造可以通过常规方法来进行，即，将正极活性物质和粘结剂、以及根据需要的导电材料和增稠剂等进行干式混合，制成片状，将所得到的片状物压接至正极集流体上；或者将这些材料溶解或分散于液体介质中而制成浆料，将该浆料涂布到正极集流体上并进行干燥，从而在集流体 上形成正极活性物质层，由此可以得到正极。
II、电解液
本申请的电化学装置中的使用的电解液包括电解质和溶解该电解质的溶剂。
本申请的电化学装置另一主要特征在于所述电解液包括二氟亚磷酸酯化合物。
在一些实施例中，所述二氟亚磷酸酯化合物包括式II化合物：
A-OPF 2(式II)，
其中A为经取代或未经取代的C1-10烷基或C3-10环烷基；
经取代时，取代基为卤素或氰基。
在一些实施例中，所述二氟亚磷酸酯化合物包括醚键。含有醚键的二氟亚磷酸酯化合物可更好地与聚(酰胺酸)相结合，使得在热失控发生时能够迅速响应而发生聚合反应，进一步提升电化学装置的浮充性能和安全性。
在一些实施例中，所述二氟亚磷酸酯化合物包括以下化合物中的至少一种：
Figure PCTCN2021142400-appb-000010
Figure PCTCN2021142400-appb-000011
在一些实施例中，基于所述电解液的重量，所述二氟亚磷酸酯化合物的含量为b％，b的取值范围为0.1至5。在一些实施例中，b的取值范围为0.5至5。在一些实施例中，x为0.1、0.5、1、1.5、2、2.5、3、3.5、4、4.5、5或在由上述任意两个数值所组成的范围内。当电解液中二氟亚磷酸酯化合物的含量在上述范围内时，有助于进一步提升电化学装置的浮充性能和安全性。
在一些实施例中，a和b满足：0.1≤a/b≤5。在一些实施例中，a和b满足：0.2≤a/b≤2.5。在一些实施例中，a和b满足：0.5≤a/b≤2。在一些实施例中，a和b满足：1≤a/b≤1.5。在一些实施例中，a/b为0.1、0.2、0.5、1、2、2.5、3、3.5、4、4.5、5或在由上述任意两个数值所组成的范围内。当正极活性物质层中聚(酰胺酸)的含量和电解液中二氟亚磷酸酯化合物的含量满足上述关系时，有助于进一步提升电化学装置的浮充性能和安全性。
在一些实施例中，所述电解液还包括含硫氧双键的化合物，所述含硫氧双键的化合物包括以下化合物中的至少一者：环状硫酸酯、链状硫酸酯、链状磺酸酯、环状磺酸酯、链状亚硫酸酯或环状亚硫酸酯或式III化合物：
Figure PCTCN2021142400-appb-000012
其中：
W选自
Figure PCTCN2021142400-appb-000013
L选自单键或亚甲基；
m为1至4的整数；
n为0至2的整数；且
p为0至6的整数。
在一些实施例中，所述式III化合物选自以下中的至少一种：
Figure PCTCN2021142400-appb-000014
当在电解液中同时包含二氟亚磷酸酯化合物和含硫氧双键化合物时，可以进一步改善热失控条件下正极活性物质的结构稳定性，同时可以加快高温下聚(酰胺酸)和二氟亚磷酸酯化合物之间热聚合反应，从而实现快速降低离子电导和电子电导，进一步改善电化学装置的浮充性能和安全性。
在一些实施例中，基于所述电解液的重量，所述二氟亚磷酸酯化合物的含量为b％，所述含硫氧双键的化合物的含量为c％，b和c满足：1≤b+c≤8和0.4≤b/c≤5。在一些实施例中，2≤b+c≤6。在一些实施例中，3≤b+c≤5。在一些实施例中，b+c为1、2、3、4、5、6、7、8或在由上述任意两个数值所组成的范围内。在一些实施例中，0.5≤b/c≤3。在一些实施例中，1≤b/c≤2。在一些实施例中，b/c为0.4、0.5、1、2、3、4、5或在由上述任意两个数值所组成的范围内。当电解液中二氟亚磷酸酯化合物的含量与含硫氧双键的化合物的含量满足上述关系时，有助于进一步提升电化学装置的浮充性能和安全性。
在一些实施例中，基于所述电解液的重量，所述含硫氧双键的化合物的含量为c％，c的取值范围为0.1至8。在一些实施例中，c的取值范围为0.1至5。在一些实施例中，其中c的取值范围为0.1至3。在一些实施例中，c的取值范围为0.1至1.5。在一些实施例中，c为0.1、0.3、0.5、1、2、2.5、3、3.5、4、4.5、5、8或在由上述任意两个数值所组成的范围内。当电解液中含硫氧双键的化合 物的含量满足上述关系时，有助于进一步提升电化学装置的浮充性能和安全性。
在一些实施例中，所述电解液进一步包含现有技术中已知的任何可作为电解液的溶剂的非水溶剂。
在一些实施例中，所述非水溶剂包括，但不限于，以下中的一种或多种：环状碳酸酯、链状碳酸酯、环状羧酸酯、链状羧酸酯、环状醚、链状醚、含磷有机溶剂、含硫有机溶剂和芳香族含氟溶剂。
在一些实施例中，所述环状碳酸酯的实例可包括，但不限于，以下中的一种或多种：碳酸亚乙酯(EC)、碳酸亚丙酯(PC)和碳酸亚丁酯。在一些实施例中，所述环状碳酸酯具有3-6个碳原子。
在一些实施例中，所述链状碳酸酯的实例可包括，但不限于，以下中的一种或多种：碳酸二甲酯、碳酸甲乙酯、碳酸二乙酯(DEC)、碳酸甲基正丙基酯、碳酸乙基正丙基酯、碳酸二正丙酯等链状碳酸酯等。被氟取代的链状碳酸酯的实例可包括，但不限于，以下中的一种或多种：双(氟甲基)碳酸酯、双(二氟甲基)碳酸酯、双(三氟甲基)碳酸酯、双(2-氟乙基)碳酸酯、双(2,2-二氟乙基)碳酸酯、双(2,2,2-三氟乙基)碳酸酯、2-氟乙基甲基碳酸酯、2,2-二氟乙基甲基碳酸酯和2,2,2-三氟乙基甲基碳酸酯等。
在一些实施例中，所述环状羧酸酯的实例可包括，但不限于，以下中的一种或多种：γ-丁内酯和γ-戊内酯中的一种或多种。在一些实施例中，环状羧酸酯的部分氢原子可被氟取代。
在一些实施例中，所述链状羧酸酯的实例可包括，但不限于，以下中的一种或多种：乙酸甲酯、乙酸乙酯、乙酸丙酯、乙酸异丙酯、乙酸丁酯、乙酸仲丁酯、乙酸异丁酯、乙酸叔丁酯、丙酸甲酯、丙酸乙酯、丙酸丙酯、丙酸异丙酯、丁酸甲酯、丁酸乙酯、丁酸丙酯、异丁酸甲酯、异丁酸乙酯、戊酸甲酯、戊酸乙酯、特戊酸甲酯和特戊酸乙酯等。在一些实施例中，链状羧酸酯的部分氢原子可被氟取代。在一些实施例中，氟取代的链状羧酸酯的实例可包括，但不限于，三氟乙酸甲酯、三氟乙酸乙酯、三氟乙酸丙酯、三氟乙酸丁酯和三氟乙酸2,2,2-三氟乙酯等。
在一些实施例中，所述环状醚的实例可包括，但不限于，以下中的一种或多种：四氢呋喃、2-甲基四氢呋喃、1,3-二氧戊环、2-甲基1,3-二氧戊环、4-甲基1,3-二氧戊环、1,3-二氧六环、1,4-二氧六环和二甲氧基丙烷。
在一些实施例中，所述链状醚的实例可包括，但不限于，以下中的一种或多种：二甲氧基甲烷、1,1-二甲氧基乙烷、1,2-二甲氧基乙烷、二乙氧基甲烷、1,1-二乙氧基乙烷、1,2-二乙氧基乙烷、乙氧基甲氧基甲烷、1,1-乙氧基甲氧基乙烷和1,2-乙氧基甲氧基乙烷等。
在一些实施例中，所述含磷有机溶剂的实例可包括，但不限于，以下中的一种或多种：磷酸三甲酯、磷酸三乙酯、磷酸二甲基乙酯、磷酸甲基二乙酯、磷酸亚乙基甲酯、磷酸亚乙基乙酯、磷酸三苯酯、亚磷酸三甲酯、亚磷酸三乙酯、亚磷酸三苯酯、磷酸三(2,2,2-三氟乙基)酯和磷酸三(2,2,3,3,3-五氟丙基)酯等。
在一些实施例中，所述含硫有机溶剂的实例可包括，但不限于，以下中的一种或多种：环丁砜、2-甲基环丁砜、3-甲基环丁砜、二甲基砜、二乙基砜、乙基甲基砜、甲基丙基砜、二甲基亚砜、甲磺酸甲酯、甲磺酸乙酯、乙磺酸甲酯、乙磺酸乙酯、硫酸二甲酯、硫酸二乙酯和硫酸二丁酯。在一些实施例中，含硫有机溶剂的部分氢原子可被氟取代。
在一些实施例中，所述芳香族含氟溶剂包括，但不限于，以下中的一种或多种：氟苯、二氟苯、三氟苯、四氟苯、五氟苯、六氟苯和三氟甲基苯。
在一些实施例中，本申请的电解液中使用的溶剂包括环状碳酸酯、链状碳酸酯、环状羧酸酯、链状羧酸酯及其组合。在一些实施例中，本申请的电解液中使用的溶剂包含选自由下列物质组成的群组的有机溶剂：碳酸亚乙酯、碳酸亚丙酯、碳酸二乙酯、丙酸乙酯、丙酸丙酯、乙酸正丙酯、乙酸乙酯及其组合。在一些实施例中，本申请的电解液中使用的溶剂包含：碳酸亚乙酯、碳酸亚丙酯、碳酸二乙酯、丙酸乙酯、丙酸丙酯、γ-丁内酯及其组合。
在一些实施例中，电解质没有特别限制，可以任意地使用作为电解质公知的物质。在锂二次电池的情况下，通常使用锂盐。电解质的实例可包括，但不限于，LiPF 6、LiBF 4、LiClO 4、LiAlF 4、LiSbF 6、LiWF 7等无机锂盐；LiWOF 5等钨酸锂类；HCO 2Li、CH 3CO 2Li、CH 2FCO 2Li、CHF 2CO 2Li、CF 3CO 2Li、CF 3CH 2CO 2Li、CF 3CF 2CO 2Li、CF 3CF 2CF 2CO 2Li、CF 3CF 2CF 2CF 2CO 2Li等羧酸锂盐类；FSO 3Li、CH 3SO 3Li、CH 2FSO 3Li、CHF 2SO 3Li、CF 3SO 3Li、CF 3CF 2SO 3Li、CF 3CF 2CF 2SO 3Li、CF 3CF 2CF 2CF 2SO 3Li等磺酸锂盐类；LiN(FCO) 2、LiN(FCO)(FSO 2)、LiN(FSO 2) 2、LiN(FSO 2)(CF 3SO 2)、LiN(CF 3SO 2) 2、LiN(C 2F 5SO 2) 2、环状1,2-全氟乙烷双磺酰亚胺锂、环状1,3-全氟丙烷双磺酰亚胺锂、LiN(CF 3SO 2)(C 4F 9SO 2)等酰亚胺锂盐类； LiC(FSO 2) 3、LiC(CF 3SO 2) 3、LiC(C 2F 5SO 2) 3等甲基化锂盐类；双(丙二酸根合)硼酸锂盐、二氟(丙二酸根合)硼酸锂盐等(丙二酸根合)硼酸锂盐类；三(丙二酸根合)磷酸锂、二氟双(丙二酸根合)磷酸锂、四氟(丙二酸根合)磷酸锂等(丙二酸根合)磷酸锂盐类；以及LiPF 4(CF 3) 2、LiPF 4(C 2F 5) 2、LiPF 4(CF 3SO 2) 2、LiPF 4(C 2F 5SO 2) 2、LiBF 3CF 3、LiBF 3C 2F 5、LiBF 3C 3F 7、LiBF 2(CF 3) 2、LiBF 2(C 2F 5) 2、LiBF 2(CF 3SO 2) 2、LiBF 2(C 2F 5SO 2) 2等含氟有机锂盐类；二氟草酸硼酸锂、双(草酸)硼酸锂等草酸硼酸锂盐类；四氟草酸根合磷酸锂、二氟双(草酸根合)磷酸锂、三(草酸根合)磷酸锂等草酸根合磷酸锂盐类等。
在一些实施例中，电解质选自LiPF 6、LiSbF 6、FSO 3Li、CF 3SO 3Li、LiN(FSO 2) 2、LiN(FSO 2)(CF 3SO 2)、LiN(CF 3SO 2) 2、LiN(C 2F 5SO 2) 2、环状1,2-全氟乙烷双磺酰亚胺锂、环状1,3-全氟丙烷双磺酰亚胺锂、LiC(FSO 2) 3、LiC(CF 3SO 2) 3、LiC(C 2F 5SO 2) 3、LiBF 3CF 3、LiBF 3C 2F 5、LiPF 3(CF 3) 3、LiPF 3(C 2F 5) 3、二氟草酸硼酸锂、双(草酸)硼酸锂或二氟双(草酸根合)磷酸锂，其有助于改善电化学装置的输出功率特性、高倍率充放电特性、高温保存特性和循环特性等。
电解质的含量没有特别限制，只要不损害本申请的效果即可。在一些实施例中，电解液中的锂的总摩尔浓度为大于0.3mol/L以上、大于0.4mol/L或大于0.5mol/L。在一些实施例中，电解液中的锂的总摩尔浓度为小于3mol/L、小于2.5mol/L或小于2.0mol/L以下。在一些实施例中，电解液中的锂的总摩尔浓度在上述任意两个数值所组成的范围内。当电解质浓度在上述范围内时，作为带电粒子的锂不会过少，并且可以使粘度处于适当的范围，因而容易确保良好的电导率。
当使用两种以上的电解质的情况下，电解质包括至少一种为选自由单氟磷酸盐、硼酸盐、草酸盐和氟磺酸盐组成的组中的盐。在一些实施例中，电解质包括选自由单氟磷酸盐、草酸盐和氟磺酸盐组成的组中的盐。在一些实施例中，电解质包括锂盐。在一些实施例中，基于电解质的重量，选自由单氟磷酸盐、硼酸盐、草酸盐和氟磺酸盐组成的组中的盐的含量为大于0.01％或大于0.1％。在一些实施例中，基于电解质的重量，选自由单氟磷酸盐、硼酸盐、草酸盐和氟磺酸盐组成的组中的盐的含量为小于20％或小于10％。在一些实施例中，选自由单氟磷酸盐、硼酸盐、草酸盐和氟磺酸盐组成的组中的盐的含量在上述任意两个数值所组成的范围内。
在一些实施例中，电解质包含选自由单氟磷酸盐、硼酸盐、草酸盐和氟磺酸盐组成的组中的一种以上物质和除此以外的一种以上的盐。作为除此以外的盐，可以举出在上文中例示的锂盐，在一些实施例中为LiPF 6、LiN(FSO 2)(CF 3SO 2)、LiN(CF 3SO 2) 2、LiN(C 2F 5SO 2) 2、环状1,2-全氟乙烷双磺酰亚胺锂、环状1,3-全氟丙烷双磺酰亚胺锂、LiC(FSO 2) 3、LiC(CF 3SO 2) 3、LiC(C 2F 5SO 2) 3、LiBF 3CF 3、LiBF 3C 2F 5、LiPF 3(CF 3) 3、LiPF 3(C 2F 5) 3。在一些实施例中，除此以外的盐为LiPF 6。
在一些实施例中，基于电解质的重量，除此以外的盐的含量为大于0.01％或大于0.1％。在一些实施例中，基于电解质的重量，除此以外的盐的含量为小于20％、小于15％或小于10％。在一些实施例中，除此以外的盐的含量在上述任意两个数值所组成的范围内。具有上述含量的除此以外的盐有助于平衡电解液的电导率和粘度。
III、负极
负极包括负极集流体和设置在所述负极集流体的一个或两个表面上的正极活性物质层，负极活性物质层包含负极活性物质。负极活性物质层可以是一层或多层，多层负极活性物质中的每层可以包含相同或不同的负极活性物质。负极活性物质为任何能够可逆地嵌入和脱嵌锂离子等金属离子的物质。在一些实施例中，负极活性物质的可充电容量大于正极活性物质的放电容量，以防止在充电期间锂金属无意地析出在负极上。
作为保持负极活性物质的集流体，可以任意使用公知的集流体。负极集流体的实例包括，但不限于，铝、铜、镍、不锈钢、镀镍钢等金属材料。在一些实施例中，负极集流体为铜。
在负极集流体为金属材料的情况下，负极集流体形式可包括，但不限于，金属箔、金属圆柱、金属带卷、金属板、金属薄膜、金属板网、冲压金属、发泡金属等。在一些实施例中，负极集流体为金属薄膜。在一些实施例中，负极集流体为铜箔。在一些实施例中，负极集流体为基于压延法的压延铜箔或基于电解法的电解铜箔。
在一些实施例中，负极集流体的厚度为大于1μm或大于5μm。在一些实施例中，负极集流体的厚度为小于100μm或小于50μm。在一些实施例中，负极集流体的厚度在上述任意两个数值所组成的范围内。
负极活性物质没有特别限制，只要能够可逆地吸藏、放出锂离子即可。负极 活性物质的实例可包括，但不限于，天然石墨、人造石墨等碳材料；硅(Si)、锡(Sn)等金属；或Si、Sn等金属元素的氧化物等。负极活性物质可以单独使用或组合使用。
负极活性物质层还可包括负极粘合剂。负极粘合剂可提高负极活性物质颗粒彼此间的结合和负极活性物质与集流体的结合。负极粘合剂的种类没有特别限制，只要是对于电解液或电极制造时使用的溶剂稳定的材料即可。在一些实施例中，负极粘合剂包括树脂粘合剂。树脂粘合剂的实例包括，但不限于，氟树脂、聚丙烯腈(PAN)、聚酰亚胺树脂、丙烯酸系树脂、聚烯烃树脂等。当使用水系溶剂制备负极合剂浆料时，负极粘合剂包括，但不限于，羧甲基纤维素(CMC)或其盐、苯乙烯-丁二烯橡胶(SBR)、聚丙烯酸(PAA)或其盐、聚乙烯醇等。
负极可以通过以下方法制备：在负极集流体上涂布包含负极活性物质、树脂粘合剂等的负极合剂浆料，干燥后，进行压延而在负极集流体的两面形成负极活性物质层，由此可以得到负极。
IV、隔离膜
为了防止短路，在正极与负极之间通常设置有隔离膜。这种情况下，本申请的电解液通常渗入该隔离膜而使用。
对隔离膜的材料及形状没有特别限制，只要不显著损害本申请的效果即可。所述隔离膜可为由对本申请的电解液稳定的材料所形成的树脂、玻璃纤维、无机物等。在一些实施例中，所述隔离膜包括保液性优异的多孔性片或无纺布状形态的物质等。树脂或玻璃纤维隔离膜的材料的实例可包括，但不限于，聚烯烃、芳香族聚酰胺、聚四氟乙烯、聚醚砜等。在一些实施例中，所述聚烯烃为聚乙烯或聚丙烯。在一些实施例中，所述聚烯烃为聚丙烯。上述隔离膜的材料可以单独使用或任意组合使用。
所述隔离膜还可为上述材料层积而成的材料，其实例包括，但不限于，按照聚丙烯、聚乙烯、聚丙烯的顺序层积而成的三层隔离膜等。
无机物的材料的实例可包括，但不限于，氧化铝、二氧化硅等氧化物、氮化铝、氮化硅等氮化物、硫酸盐(例如，硫酸钡、硫酸钙等)。无机物的形式可包括，但不限于，颗粒状或纤维状。
所述隔离膜的形态可为薄膜形态，其实例包括，但不限于，无纺布、织布、微多孔性膜等。在薄膜形态中，所述隔离膜的孔径为0.01μm至1μm，厚度为5 μm至50μm。除了上述独立的薄膜状隔离膜以外，还可以使用下述隔离膜：通过使用树脂类的粘合剂在正极和/或负极的表面形成含有上述无机物颗粒的复合多孔层而形成的隔离膜，例如，将氟树脂作为粘合剂使90％粒径小于1μm的氧化铝颗粒在正极的两面形成多孔层而形成的隔离膜。
所述隔离膜的厚度是任意的。在一些实施例中，所述隔离膜的厚度为大于1μm、大于5μm或大于8μm。在一些实施例中，所述隔离膜的厚度为小于50μm、小于40μm或小于30μm。在一些实施例中，所述隔离膜的厚度在上述任意两个数值所组成的范围内。当所述隔离膜的厚度在上述范围内时，则可以确保绝缘性和机械强度，并可以确保电化学装置的倍率特性和能量密度。
在使用多孔性片或无纺布等多孔质材料作为隔离膜时，隔离膜的孔隙率是任意的。在一些实施例中，所述隔离膜的孔隙率为大于10％、大于15％或大于20％。在一些实施例中，所述隔离膜的孔隙率为小于60％、小于50％或小于45％。在一些实施例中，所述隔离膜的孔隙率在上述任意两个数值所组成的范围内。当所述隔离膜的孔隙率在上述范围内时，可以确保绝缘性和机械强度，并可以抑制膜电阻，使电化学装置具有良好的安全特性。
所述隔离膜的平均孔径也是任意的。在一些实施例中，所述隔离膜的平均孔径为小于0.5μm或小于0.2μm。在一些实施例中，所述隔离膜的平均孔径为大于0.05μm。在一些实施例中，所述隔离膜的平均孔径在上述任意两个数值所组成的范围内。若所述隔离膜的平均孔径超过上述范围，则容易发生短路。当隔离膜的平均孔径在上述范围内时，使电化学装置具有良好的安全特性。
V、电化学装置组件
电化学装置组件包括电极组、集电结构、外装壳体和保护元件。
电极组可以是由上述正极和负极隔着上述隔离膜层积而成的层积结构、以及上述正极和负极隔着上述隔离膜以漩涡状卷绕而成的结构中的任一种。在一些实施例中，电极组的质量在电池内容积中所占的比例(电极组占有率)为大于40％或大于50％。在一些实施例中，电极组占有率为小于90％或小于80％。在一些实施例中，电极组占有率在上述任意两个数值所组成的范围内。当电极组占有率在上述范围内时，可以确保电化学装置的容量，同时可以抑制与内部压力上升相伴的反复充放电性能及高温保存等特性的降低。
集电结构没有特别限制。在一些实施例中，集电结构为降低配线部分及接合 部分的电阻的结构。当电极组为上述层积结构时，适合使用将各电极层的金属芯部分捆成束而焊接至端子上所形成的结构。一片的电极面积增大时，内部电阻增大，因而在电极内设置2个以上的端子而降低电阻也是适合使用的。当电极组为上述卷绕结构时，通过在正极和负极分别设置2个以上的引线结构，并在端子上捆成束，从而可以降低内部电阻。
外装壳体的材质没有特别限制，只要是对于所使用的电解液稳定的物质即可。外装壳体可使用，但不限于，镀镍钢板、不锈钢、铝或铝合金、镁合金等金属类、或者树脂与铝箔的层积膜。在一些实施例中，外装壳体为铝或铝合金的金属或层积膜。
金属类的外装壳体包括，但不限于，通过激光焊接、电阻焊接、超声波焊接将金属彼此熔敷而形成的封装密闭结构；或者隔着树脂制垫片使用上述金属类形成的铆接结构。使用上述层积膜的外装壳体包括，但不限于，通过将树脂层彼此热粘而形成的封装密闭结构等。为了提高密封性，还可以在上述树脂层之间夹入与层积膜中所用的树脂不同的树脂。在通过集电端子将树脂层热粘而形成密闭结构时，由于金属与树脂的接合，可使用具有极性基团的树脂或导入了极性基团的改性树脂作为夹入的树脂。另外，外装体的形状也是任意的，例如可以为圆筒形、方形、层积型、纽扣型、大型等中的任一种。
保护元件可以使用在异常放热或过大电流流过时电阻增大的正温度系数(PTC)、温度熔断器、热敏电阻、在异常放热时通过使电池内部压力或内部温度急剧上升而切断在电路中流过的电流的阀(电流切断阀)等。上述保护元件可选择在高电流的常规使用中不工作的条件的元件，亦可设计成即使不存在保护元件也不至于发生异常放热或热失控的形式。
本申请的电化学装置包括发生电化学反应的任何装置，它的具体实例包括锂金属二次电池或锂离子二次电池。
本申请另提供了一种电子装置，其包括根据本申请所述的电化学装置。
本申请的电化学装置的用途没有特别限定，其可用于现有技术中已知的任何电子装置。在一些实施例中，本申请的电化学装置可用于，但不限于，笔记本电脑、笔输入型计算机、移动电脑、电子书播放器、便携式电话、便携式传真机、便携式复印机、便携式打印机、头戴式立体声耳机、录像机、液晶电视、手提式清洁器、便携CD机、迷你光盘、收发机、电子记事本、计算器、存储卡、便携 式录音机、收音机、备用电源、电机、汽车、摩托车、助力自行车、自行车、照明器具、玩具、游戏机、钟表、电动工具、闪光灯、照相机、家庭用大型蓄电池和锂离子电容器等。
下面以锂离子电池为例并且结合具体的实施例说明锂离子电池的制备，本领域的技术人员将理解，本申请中描述的制备方法仅是实例，其他任何合适的制备方法均在本申请的范围内。
实施例
一、锂离子电池的制备
1、负极的制备
将人造石墨、丁苯橡胶和羧甲基纤维素钠按照96％:2％:2％的质量比例与去离子水混合，搅拌均匀，得到负极浆料。将该负极浆料涂布在9μm的铜箔上，干燥，冷压，再经过裁片、焊接极耳，得到负极。
2、正极的制备
将钴酸锂(杉杉LC9000E)、Super-P和聚偏氟乙烯按照97:1:2的质量比例与N-甲基吡咯烷酮(NMP)混合，再加入聚(酰胺酸)(化学式I-1，其中化学式I-1a中n＝5、化学式I-1b中n＝10、化学式I-1c中n＝15、化学式I-1d中n＝20)，搅拌均匀，得到正极浆料。将该正极浆料涂布在12μm的铝箔上，干燥，冷压，再经过裁片、焊接极耳，得到正极。
3、电解液的制备
在干燥氩气环境下，将EC、PC和DEC(重量比1:1:1)混合，加入LiPF 6混合均匀，形成基础电解液，其中LiPF 6的浓度为12.5％。在基础电解液中加入不同含量添加剂得到不同实施例和对比例的电解液。
电解液中组分的缩写及其名称如下表所示：
材料名称 缩写 材料名称 缩写
碳酸乙烯酯 EC 碳酸丙烯酯 PC
碳酸二乙酯 DEC 式II-1化合物 式II-1
式II-2化合物 式II-2 式II-3化合物 式II-3
式II-4化合物 式II-4 式II-5化合物 式II-5
式II-6化合物 式II-6 式II-7化合物 式II-7
式II-8化合物 式II-8 式II-9化合物 式II-9
1,3-丙磺酸内酯 PS 硫酸乙烯酯 DTD
式III-1化合物 式III-1 式III-3化合物 式III-3
式III-4化合物 式III-4    
4、隔离膜的制备
以聚乙烯多孔聚合物薄膜作为隔离膜。
5、锂离子电池的制备
将得到的正极、隔离膜和负极按次序卷绕，置于外包装箔中，留下注液口。从注液口灌注电解液，封装，再经过化成、容量等工序制得锂离子电池。
二、测试方法
1、锂离子电池的高温短路变形率的测试方法
在25℃下，将锂离子电池静置30分钟，然后以0.5C倍率恒流充电至4.7V，再在4.7V下恒压充电至0.05C，静置60分钟，测量锂离子电池的厚度T 1。然后以100mΩ使锂离子电池短路10秒钟，然后测量锂离子电池的厚度T 2。通过下式计算锂离子电池高温短路变形率：
短路变形率＝[(T 2-T 1)/T 1]×100％。
2、锂离子电池过充变形率的测试方法
在25℃下，将锂离子电池静置30分钟，然后以0.5C倍率恒流充电至4.7V，再在4.7V下恒压充电至0.05C，静置60分钟，测量锂离子电池的厚度H 1。然后将锂离子电池以0.1C倍率恒流充电60分钟，静置30分钟，重复这一步骤5次，使锂离子电池达到150％荷电状态(SOC)，测量锂离子电池的厚度H 2。通过下式计算锂离子电池的过充变形率：
过充变形率＝[(H 2-H 1)/H 1]×100％。
3、锂离子电池高温高压下浮充性能的测试方法
在25℃下，将锂离子电池以0.5C恒流充电至4.7V，再在4.7V下恒压充电至0.05C。然后将锂离子电池置于50℃烘箱中，以4.7V持续恒压充电(截至电流为20mA)，监控锂离子电池的厚度的变化。以初始50％充电状态(SOC)时锂离子电池的厚度作为基准，当锂离子电池厚度增加超过20％时记为失效。记录锂离子电池在50℃下浮充至失效的时间，以小时(h)作为统计单位。
三、测试结果
表1展示了正极活性物质和电解液对锂离子电池的浮充性能和安全性的影响，其中二氟亚磷酸酯化合物为式II-1化合物。
表1
Figure PCTCN2021142400-appb-000015
如对比例1-1所示，虽然电解液包括二氟亚磷酸酯化合物，但正极活性物质不包括聚(酰胺酸)，锂离子电池的过充变形率和短路变形率较高且浮充失效时间较短。如对比例1-2所示，虽然正极活性物质包括聚(酰胺酸)，但电解液不包括二氟亚磷酸酯化合物，锂离子电池的过充变形率和短路变形率较高且浮充失效时间较短。
如实施例1-1至1-17所示，当正极活性物质包括聚(酰胺酸)且电解液包括二氟亚磷酸酯化合物时，可显著降低锂离子电池的过充变形率和短路变形率并显著提升其浮充失效时间。不同结构的聚(酰胺酸)可实现基本相当的效果。
此外，当正极活性物质层中聚(酰胺酸)的含量a％与电解液中二氟亚磷酸酯化合物的含量b％满足0.1≤a/b≤5时，可进一步降低锂离子电池的过充变形率和短路变形率并提升其浮充失效时间。
当正极活性物质层中聚(酰胺酸)的含量在0.5％-5％的范围内时，可进一步降 低锂离子电池的过充变形率和短路变形率并提升其浮充失效时间。
当电解液中二氟亚磷酸酯化合物的含量在0.1％至5％的范围内时，可进一步降低锂离子电池的过充变形率和短路变形率并提升其浮充失效时间。
表2展示了不同结构二氟亚磷酸酯化合物对锂离子电池的浮充性能和安全性的影响。除表2中所列参数以外，实施例2-1至2-8与实施例1-1的设置相同。
表2
  二氟亚磷酸酯化合物 过充变形率(％) 短路变形率(％) 浮充失效时间(h)
实施例1-1 式II-1 16.9 17.8 805
实施例2-1 式II-2 15.3 16.4 835
实施例2-2 式II-3 15.2 16.5 842
实施例2-3 式II-4 15.3 16.2 879
实施例2-4 式II-5 12.3 12.6 1006
实施例2-5 式II-6 11.6 11.9 1021
实施例2-6 式II-7 13.7 12.5 978
实施例2-7 式II-8 13.2 12.1 993
实施例2-8 式II-9 12.6 11.8 1068
结果表明，不同结构的二氟亚磷酸酯化合物可实现基本相当的效果。当二氟亚磷酸酯化合物中含有醚键(实施例2-4、2-5和2-8)时，可进一步降低锂离子电池的过充变形率和短路变形率并提升其浮充失效时间。
表3展示了含硫氧双键化合物对锂离子电池的浮充性能和安全性的影响，其中电解液中含硫氧双键化合物的含量为1％。除表3中所列参数以外，实施例3-1至3-5与实施例1-1的设置相同。
表3
  含硫氧双键化合物 过充变形率(％) 短路变形率(％) 浮充失效时间(h)
实施例1-1 — 16.9 17.8 805
实施例3-1 PS 13.6 14.5 815
实施例3-2 DTD 13.2 14.2 811
实施例3-3 式III-1 13.7 14.8 823
实施例3-4 式III-3 11.5 11.9 895
实施例3-5 式III-4 11.2 10.5 1124
结果表明，当电解液进一步包括含硫氧双键化合物时，可进一步降低锂离子电池的过充变形率和短路变形率并提升其浮充失效时间。
表4展示了电解液中二氟亚磷酸酯化合物和含硫氧双键化合物的含量关系对锂离子电池的浮充性能和安全性的影响。除表4中所列参数以外，实施例4-1 至4-9与实施例1-1的设置相同。
表4
Figure PCTCN2021142400-appb-000016
结果表明，当电解液中二氟亚磷酸酯化合物的含量b％与含硫氧双键化合物的含量c％满足1≤b+c≤8和0.4≤b/c≤5时，可进一步降低锂离子电池的过充变形率和短路变形率并提升其浮充失效时间。
整个说明书中对“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，其包括：正极、负极和电解液，所述正极包括正极集流体和形成在所述正极集流体上的正极活性物质层，其中：
    所述正极活性物质层包括聚(酰胺酸)，并且
    所述电解液包括二氟亚磷酸酯化合物。
  2. 根据权利要求1所述的电化学装置，其中：
    基于所述正极活性物质层的重量，所述聚(酰胺酸)的含量为a％；
    基于所述电解液的重量，所述二氟亚磷酸酯化合物的含量为b％；且
    a和b满足：0.1≤a/b≤5。
  3. 根据权利要求2所述的电化学装置，其中a的取值范围为0.5至5。
  4. 根据权利要求2所述的电化学装置，其中b的取值范围为0.1至5。
  5. 根据权利要求1所述的电化学装置，其中所述聚(酰胺酸)包括式I化合物：
    Figure PCTCN2021142400-appb-100001
    其中：
    R选自C1-12烯基或C6-12芳环；
    A选自单键、C1-12烯基或C6-12芳环；
    n为5至20的整数。
  6. 根据权利要求1所述的电化学装置，其中所述二氟亚磷酸酯化合物包括式II化合物：
    A-OPF 2(式II)，
    其中A为经取代或未经取代的C1-10烷基或C3-10环烷基；
    经取代时，取代基为卤素或氰基。
  7. 根据权利要求1所述的电化学装置，其中所述二氟亚磷酸酯化合物包括以下化合物中的至少一种：
    Figure PCTCN2021142400-appb-100002
  8. 根据权利要求1所述的电化学装置，其中所述电解液还包括含硫氧双键 的化合物，所述含硫氧双键的化合物包括以下化合物中的至少一者：环状硫酸酯、链状硫酸酯、链状磺酸酯、环状磺酸酯、链状亚硫酸酯或环状亚硫酸酯或式III化合物：
    Figure PCTCN2021142400-appb-100003
    其中：
    W选自
    Figure PCTCN2021142400-appb-100004
    L选自单键或亚甲基；
    m为1至4的整数；
    n为0至2的整数；且
    p为0至6的整数。
  9. 根据权利要求8所述的电化学装置，其中所述式III化合物选自以下中的至少一种：
    Figure PCTCN2021142400-appb-100005
  10. 根据权利要求8所述的电化学装置，其中基于所述电解液的重量，所述二氟亚磷酸酯化合物的含量为b％，所述含硫氧双键的化合物的含量为c％，b和c满足：1≤b+c≤8和0.4≤b/c≤5。
  11. 根据权利要求8所述的电化学装置，其中基于所述电解液的重量，所述含硫氧双键的化合物的含量为c％，c的取值范围为0.1至8。
  12. 根据权利要求11所述的电化学装置，其中c的取值范围为0.1至1.5。
  13. 一种电子装置，其包括根据权利要求1-12中任一项所述的电化学装置。
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