WO2021237664A1 - 电解液和包括电解液的电化学装置及电子装置 - Google Patents

电解液和包括电解液的电化学装置及电子装置 Download PDF

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WO2021237664A1
WO2021237664A1 PCT/CN2020/093220 CN2020093220W WO2021237664A1 WO 2021237664 A1 WO2021237664 A1 WO 2021237664A1 CN 2020093220 W CN2020093220 W CN 2020093220W WO 2021237664 A1 WO2021237664 A1 WO 2021237664A1
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group
substituted
electrolyte
unsubstituted
compound
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PCT/CN2020/093220
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English (en)
French (fr)
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熊亚丽
管明明
王荣
郑建明
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宁德新能源科技有限公司
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Priority to PCT/CN2020/093220 priority Critical patent/WO2021237664A1/zh
Priority to CN202080005688.6A priority patent/CN112868123B/zh
Publication of WO2021237664A1 publication Critical patent/WO2021237664A1/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
    • H01M2300/00—Electrolytes
    • H01M2300/0017—Non-aqueous electrolytes
    • H01M2300/0025—Organic electrolyte
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Definitions

  • This application relates to the field of energy storage technology, in particular to electrolytes and electrochemical devices and electronic devices including electrolytes.
  • Electrochemical devices such as lithium secondary batteries, have the advantages of high working voltage, high specific energy density, long cycle life, low self-discharge rate, no memory effect, and low environmental pollution. They have been widely used in various consumer electronics markets. The ideal power source for electric vehicles and various electric tools in the future.
  • Electrolyte is an important part of lithium secondary batteries.
  • Sulfonate additives include propane sultone, propene sultone, butane sultone or sulfite, etc., which are widely used in current commercial electrolytes. They can not only improve the storage of lithium-ion batteries at high temperatures. And cycle performance, and also shows a good effect on suppressing battery flatulence.
  • propane sultone which is currently the most widely used and has the best comprehensive performance, has carcinogenic properties and has been listed as a key concern in the European Union. Therefore, the development of sulfonate substitute products with better comprehensive performance has become an urgent technical problem in the industry. .
  • the present application provides an electrolyte and an electrochemical device including the electrolyte in an attempt to solve at least one problem in the related field at least to some extent.
  • This application provides an electrolyte containing an internal salt compound with zwitterions, which not only does not cause harm to the human body, but also can effectively improve the high-temperature cycle performance and high-rate discharge performance of electrochemical devices. And effectively reduce internal resistance.
  • the present application provides an electrolyte, which contains a compound of formula I
  • the compound of formula I comprises:
  • the content of the compound of formula I is 0.05 wt% to 3.5 wt%.
  • the electrolyte further includes lithium difluorophosphate, and based on the weight of the electrolyte, the content of the lithium difluorophosphate is less than 1 wt%.
  • the content a% of the compound of formula I and the content b% of the lithium difluorophosphate satisfy a+b ⁇ 4.5 and a/b> 1:10.
  • the electrolyte further includes a nitrile compound
  • the nitrile compound includes at least one of the compounds represented by Formula II, Formula III, or Formula IV:
  • R 21 is selected from substituted or unsubstituted C 1 to C 10 alkylene, substituted or unsubstituted C 2 to C 10 alkenylene, or C 2 to C 6 linear or branched chain containing at least one ether bond
  • the alkylene or alkenylene group, when substituted, the substituent is at least one of a halogen atom, a nitro group, a cyano group, a carboxyl group or a sulfate group
  • R 31 , R 32 , and R 33 are each independently selected from Single bond, substituted or unsubstituted C 1 to C 10 alkylene or C 2 to C 6 linear or branched alkylene or alkenylene containing at least one ether bond, wherein when substituted, the substituent is At least one of halogen atom, nitro group, cyano group, carboxyl group or sulfate group
  • R 41 is selected from substituted or unsubstituted C 1 to C 10 alkylene,
  • the nitrile compound comprises
  • the electrolyte further includes a phosphate compound
  • the phosphate compound includes a compound of formula V
  • R 51 , R 52 , R 53 are each independently selected from hydrogen, substituted or unsubstituted C 1 to C 5 alkyl, substituted or unsubstituted C 2 to C 10 alkenyl, substituted or unsubstituted C 6 to A C 10 aryl group or a substituted or unsubstituted C 1 to C 6 heterocyclic group, wherein when substituted, the substituent is a halogen atom, a nitro group, a cyano group, a carboxyl group, a sulfate group, a phosphate group or a silyl group At least one of; wherein based on the weight of the electrolyte, the content of the phosphate compound is 0.1wt%-10wt%.
  • the phosphate compound comprises
  • the electrolyte includes a non-aqueous organic solvent, wherein the non-aqueous organic solvent includes ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, ⁇ - Butyrolactone, methyl acetate, ethyl acetate, propyl acetate, butyl acetate, methyl propionate, ethyl propionate, propyl propionate, butyl propionate, methyl butyrate, ethyl butyrate or At least one of propyl butyrate.
  • the non-aqueous organic solvent includes ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, ⁇ - Butyrolactone, methyl acetate, ethyl acetate, propyl acetate, butyl acetate, methyl propionate, ethyl propionate, propyl prop
  • the present application also provides an electrochemical device, which includes a positive electrode, a negative electrode, a separator, and any one of the electrolytes described above.
  • the negative electrode in the electrochemical device, includes a negative electrode active material, and the OI value of the negative electrode active material is 8-15.
  • the positive electrode in the electrochemical device, includes a positive electrode active material, and based on each gram of the positive electrode active material, the content of the compound of formula I in the electrolyte is 0.025 g-0.35 g.
  • the present application also provides an electronic device, which includes any electrochemical device as described above.
  • Figure 1 is a 1 H NMR spectrum of the compound of formula I-1 (solvent: D 2 O).
  • the terms “approximately”, “substantially”, “substantially” and “about” are used to describe and illustrate small changes.
  • the term may refer to an example in which the event or situation occurs precisely and an example in which the event or situation occurs very closely.
  • the term can refer to a range of variation less than or equal to ⁇ 10% of the stated value, such as less than or equal to ⁇ 5%, less than or equal to ⁇ 4%, less than or equal to ⁇ 3%, Less than or equal to ⁇ 2%, less than or equal to ⁇ 1%, less than or equal to ⁇ 0.5%, less than or equal to ⁇ 0.1%, or less than or equal to ⁇ 0.05%.
  • the difference between two values is less than or equal to ⁇ 10% of the average value of the value (for example, less than or equal to ⁇ 5%, less than or equal to ⁇ 4%, less than or equal to ⁇ 3%, less than Or equal to ⁇ 2%, less than or equal to ⁇ 1%, less than or equal to ⁇ 0.5%, less than or equal to ⁇ 0.1%, or less than or equal to ⁇ 0.05%), then the two values can be considered "substantially" the same.
  • a list of items connected by the terms “at least one of”, “at least one of”, “at least one of” or other similar terms may mean the listed items Any combination of. For example, if items A and B are listed, then the phrase “at least one of A and B” means only A; only B; or A and B. In another example, if items A, B, and C are listed, then the phrase "at least one of A, B, and C" means only A; or only B; only C; A and B (excluding C); A and C (exclude B); B and C (exclude A); or all of A, B, and C.
  • Project A can contain a single component or multiple components.
  • Project B can contain a single component or multiple components.
  • Item C can contain a single component or multiple components.
  • alkyl is intended to be a linear saturated hydrocarbon structure having 1 to 20 carbon atoms.
  • Alkyl is also expected to be a branched or cyclic hydrocarbon structure having 3 to 20 carbon atoms.
  • the alkyl group may be an alkyl group of 1 to 20 carbon atoms, an alkyl group of 1 to 10 carbon atoms, an alkyl group of 1 to 5 carbon atoms, an alkyl group of 5 to 20 carbon atoms, and an alkyl group of 5 to 15 carbon atoms.
  • butyl means to include n-butyl, sec-butyl, isobutyl, and 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.
  • the alkyl group may be optionally substituted.
  • alkylene alone or as part of another substituent means a divalent radical derived from an alkyl group.
  • alkenyl refers to a monovalent unsaturated hydrocarbon group that may be linear or branched and has at least one and usually 1, 2, or 3 carbon-carbon double bonds. Unless otherwise defined, the alkenyl group usually contains 2 to 20 carbon atoms, for example, it can be an alkenyl group of 2 to 20 carbon atoms, an alkenyl group of 6 to 20 carbon atoms, or an alkenyl group of 2 to 10 carbon atoms. Group or alkenyl with 2-6 carbon atoms.
  • alkenyl groups include, for example, vinyl, n-propenyl, isopropenyl, n-but-2-enyl, but-3-enyl, n-hex-3-enyl, and the like. In addition, alkenyl groups may be optionally substituted.
  • alkenylene encompasses straight chain and branched chain alkenylene groups. When an alkenylene group having a specific carbon number is specified, it is expected to encompass all geometric isomers having that carbon number.
  • the alkenylene group may be an alkenylene group of 2 to 20 carbon atoms, an alkenylene group of 2 to 15 carbon atoms, an alkenylene group of 2 to 10 carbon atoms, or an alkenylene group of 2 to 5 carbon atoms.
  • Representative alkylene groups include, for example, vinylene, propenylene, butenylene, and the like.
  • alkenylene groups may be optionally substituted.
  • alkynyl refers to a monovalent unsaturated hydrocarbon group that may be linear or branched and has at least one and usually 1, 2, or 3 carbon-carbon triple bonds. Unless otherwise defined, the alkynyl group usually contains 2 to 20 carbon atoms, for example, it can be an alkynyl group of 2 to 20 carbon atoms, an alkynyl group of 6 to 20 carbon atoms, or an alkynyl group of 2 to 10 carbon atoms. Group or an alkynyl group of 2 to 6 carbon atoms.
  • alkynyl groups include, for example, ethynyl, prop-2-ynyl (n-propynyl), n-but-2-ynyl, n-hex-3-ynyl, and the like. In addition, alkynyl groups may be optionally substituted.
  • aryl encompasses monocyclic and polycyclic ring systems.
  • a polycyclic ring may have two or more rings in which two carbons are shared by two adjacent rings (the rings are "fused"), wherein at least one of the rings is aromatic, such as others
  • the ring can be a cycloalkyl, cycloalkenyl, aryl, heterocyclic, and/or heteroaryl group.
  • the aryl group may be a C 6 to C 50 aryl group, a C 6 to C 40 aryl group, a C 6 to C 30 aryl group, a C 6 to C 20 aryl group, or a C 6 to C 10 aryl group.
  • aryl groups include, for example, phenyl, methylphenyl, propylphenyl, isopropylphenyl, benzyl and naphth-1-yl, naphth-2-yl, and the like. In addition, aryl groups may be optionally substituted.
  • arylene alone or as part of another substituent means a divalent radical derived from an aryl group.
  • heterocyclic group encompasses aromatic and non-aromatic cyclic groups. Heteroaromatic cyclic group also means heteroaryl.
  • the heteroaromatic ring group and the heteronon-aromatic ring group are a C 1 to C 50 heterocyclic group, a C 1 to C 40 heterocyclic group, a C 1 to C 30 heterocyclic group including at least one heteroatom Heterocyclic group, C 1 to C 20 heterocyclic group, C 1 to C 10 heterocyclic group, C 1 to C 6 heterocyclic group.
  • heteroatoms include O, S, P, N, B or isosteres.
  • heterocyclic groups may be optionally substituted.
  • sil group is expected to be a free radical derived from silane, such as -SiH 3 or -Si(CH 3 ) 3 and the like.
  • halogen can be F, Cl, Br, or I.
  • the embodiments of the present application provide an electrolyte and an electrochemical device and an electronic device including the electrolyte.
  • the electrochemical device is a lithium ion battery.
  • the embodiment of the present application provides an electrolyte, which includes an organic solvent, an electrolyte, and an additive, and the additive includes a compound of formula I.
  • the electrolyte is a non-aqueous electrolyte
  • the electrolyte contains a compound of formula I
  • the compound of formula I comprises:
  • the above-mentioned compound of formula I can be synthesized by the ring-opening reaction of each corresponding amine and sultone.
  • the ring-opening reaction can be carried out in air, preferably in a dry atmosphere, such as dry air, nitrogen or argon.
  • the reaction of the compound of formula I as described above is generally between -5°C and 30°C, preferably 0°C to room temperature.
  • the reaction formula for synthesizing the compound of formula I-1 is as follows:
  • the compound of formula I was characterized by NMR spectroscopy.
  • NMR samples were measured in a Bruker Avance III spectrometer equipped with a 9.3980T cryogenic magnet in a 5mm NMR tube at 25°C.
  • a 5mm combined 1 H measuring head operating at 400.17 and 376.54 MHz was used to measure the 1 H NMR spectrum.
  • the 13 C NMR spectrum was obtained by using a 5 mm broadband inverse measuring head at 100.62 MHz.
  • the reference in the case of 1 H NMR spectroscopy is tetramethylsilane (TMS), which uses the chemical shift ( ⁇ ) of the solvent heavy water D 2 O (4.80 ppm).
  • Figure 1 is the 1 H NMR spectrum of formula I-1 (solvent: D 2 O).
  • 1-7 in the figure represent the first to seventh peaks, in which the ⁇ (ppm) of the first to seventh peaks are respectively Yes: 3.39 (m, 2H), 3.28 (m, 4H), 2.94 (s, 3H), 2.87 (t, 2H), 2.11 (m, 2H), 1.77 (m, 4H), 1.55 (m, 2H).
  • the compound of formula I is an internal salt compound containing zwitterions, which will not cause harm to the human body, and can increase the dissociation degree of lithium salt, increase the conductivity of the electrolyte, and can significantly improve the high-rate discharge performance, effectively reducing The internal resistance of the electrochemical device; at the same time, because the internal salt compound has a sulfonate structure, it is helpful to form a more stable passivation film on the surface of the positive and negative electrodes on the surface of the negative electrode and the positive electrode. Cycle performance and storage performance.
  • the content of the compound of formula I is 0.05 wt% to 3.5 wt% based on the weight of the electrolyte. In some embodiments, based on the weight of the electrolyte, the content of the compound of formula I is about 0.1% by weight, about 0.2% by weight, about 0.3% by weight, about 0.4% by weight, about 0.5% by weight, about 0.7% by weight, about 1% by weight.
  • % about 1.5wt%, about 2wt%, about 2.5wt%, about 3wt%, 0.1wt%-0.5wt%, 0.1wt%-1wt%, 0.5wt%-1wt%, 1wt%-2wt%, 2wt% -3wt%, 1wt%-3wt%, or 1wt%-3.5wt%, etc.
  • the electrolyte may further include lithium difluorophosphate (LiPO 2 F 2 ). Adding lithium difluorophosphate can further increase the composition of LiF in the organic protective film, and increase the stability of the electrolyte, thereby improving the cycle and reducing the impedance of the electrochemical device.
  • LiPO 2 F 2 lithium difluorophosphate
  • the content of lithium difluorophosphate is less than about 1 wt% based on the weight of the electrolyte. In some embodiments, based on the weight of the electrolyte, the content of lithium difluorophosphate is less than about 0.05% by weight, about 0.1% by weight, about 0.2% by weight, about 0.3% by weight, about 0.4% by weight, about 0.5% by weight, about 0.6% by weight, about 0.7% by weight, about 0.8% by weight, about 0.9% by weight, or about 1% by weight, etc.
  • the content a% of the compound of formula I and the content b% of the lithium difluorophosphate satisfy a+b ⁇ 4.5 and a/b>1:10.
  • a+b ⁇ 4.5 the added amount of additives will affect the transmission of lithium ions, which will deteriorate the performance of the electrochemical device; when a/b ⁇ 1/10, the added amount of the compound of formula I is less. There is no obvious improvement effect.
  • the electrolyte further includes a nitrile compound, and the nitrile compound includes at least one of Formula II, Formula III, or Formula IV:
  • R 21 is selected from a substituted or unsubstituted C 1 to C 10 alkylene group, a substituted or unsubstituted C 2 to C 10 alkenylene group, or a C 2 to C 6 straight chain containing at least one ether bond Or a branched alkylene or alkenylene group, wherein when substituted, the substituent is at least one of a halogen atom, a nitro group, a cyano group, a carboxyl group, or a sulfuric acid group.
  • R 31 , R 32 , and R 33 are each independently selected from a single bond, a substituted or unsubstituted C 1 to C 10 alkylene group, or a C 2 to C 6 linear or branched chain containing at least one ether bond.
  • the alkylene or alkenylene of the chain, when substituted, the substituent is at least one of a halogen atom, a nitro group, a cyano group, a carboxyl group, or a sulfuric acid group.
  • R 41 is selected from substituted or unsubstituted C 1 to C 10 alkylene, substituted or unsubstituted C 2 to C 10 alkenylene, substituted or unsubstituted C 6 to C 10 arylene , Substituted or unsubstituted C 3 to C 6 cycloalkylene or substituted or unsubstituted C 6 to C 10 heterocyclic group, wherein when substituted, the substituent is a halogen atom, a nitro group, a cyano group, a carboxyl group or At least one of the sulfate groups, wherein the heterocyclic group includes at least one of O, S, N, or P.
  • the nitrile compound comprises
  • the combined action of the nitrile compound and the compound of formula I can further improve the protective film on the surface of the positive and negative electrodes and reduce the side reactions between the positive and negative electrodes and the electrolyte, thereby improving the cycle performance and high-temperature storage performance of the electrochemical device.
  • the content of the nitrile compound in the range of 0.5 wt% to 10 wt% can significantly improve the performance of the electrochemical device, enabling the electrochemical device to obtain better cycle performance and high-temperature storage performance.
  • the content of the nitrile compound is about 0.5% by weight, about 1% by weight, about 1.5% by weight, about 2% by weight, about 2.5% by weight, about 3% by weight, about 3.5% by weight, about 4wt%, about 4.5wt%, about 5wt%, about 5.5wt%, about 6wt%, about 7wt%, about 8wt%, about 9wt%, about 10wt%, 0.5wt%-1wt%, 0.5wt%-2wt% , 0.5wt%-3wt%, 1wt%-3wt%, 1wt%-6wt%, 1.5wt%-5wt%, 1.5wt%-6wt%, 2wt%-5wt%, 3wt%-6wt% or 5wt%-10wt %Wait.
  • the electrolyte of the present application may further include a phosphate compound, and the phosphate compound includes a compound of formula V
  • R 51 , R 52 , and R 53 are each independently selected from hydrogen, substituted or unsubstituted C 1 to C 5 alkyl, substituted or unsubstituted C 2 to C 10 alkenyl, substituted or unsubstituted C 6 to C 10 aryl or substituted or unsubstituted C 1 to C 6 heterocyclic group, wherein when substituted, the substituent is a halogen atom, a nitro group, a cyano group, a carboxyl group, a sulfate group, a phosphate group Or at least one of silyl groups.
  • the phosphate compound comprises
  • the phosphate compound and the compound of formula I work together to further improve the thermal stability of the electrochemical device and prevent thermal runaway of the electrochemical device.
  • the content of the phosphate compound is 0.1 wt% to 10 wt%. When the content of the phosphate compound is within this range, the film-forming effect is more pronounced, and a more excellent protective film can be obtained. In some embodiments, based on the weight of the electrolyte, the content of the phosphate compound is about 0.1 wt%, about 0.5 wt%, about 1 wt%, about 2 wt%, about 3 wt%, about 5 wt%, about 6 wt%, about 7 wt%.
  • % about 8wt%, about 9wt%, about 10wt%, 0.1wt%-1wt%, 0.5wt%-1wt%, 0.1wt%-5wt%, 1wt%-5wt%, 1wt%-10wt% or 5wt%- 10wt% etc.
  • the electrolyte further includes a non-aqueous organic solvent, wherein the non-aqueous organic solvent includes ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, ⁇ -butyrol Ester, methyl acetate, ethyl acetate, propyl acetate, butyl acetate, methyl propionate, ethyl propionate, propyl propionate, butyl propionate, methyl butyrate, ethyl butyrate or butyrate At least one of propyl esters.
  • the non-aqueous organic solvent includes ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, ⁇ -butyrol Ester, methyl acetate, ethyl acetate, propyl acetate, butyl acetate, methyl propionate, ethyl propionate, prop
  • the electrolyte further includes a lithium salt selected from lithium hexafluorophosphate (LiPF 6 ), lithium bistrifluoromethanesulfonimide (LiN(CF 3 SO 2 ) 2 ), bis(fluorosulfonyl )Lithium imide (LiN(SO 2 F) 2 )), lithium bisoxalate borate (LiB(C 2 O 4 ) 2 ), lithium tetrafluorophosphate oxalate (LiPF 4 C 2 O 2 ), lithium difluorooxalate ( At least one of LiBF 2 (C 2 O 4 )) or lithium hexafluorocesium oxide (LiCsF 6 ).
  • a lithium salt selected from lithium hexafluorophosphate (LiPF 6 ), lithium bistrifluoromethanesulfonimide (LiN(CF 3 SO 2 ) 2 ), bis(fluorosulfonyl )Lithium imide
  • the concentration of the lithium salt in the electrolyte is 0.5 mol/L-1.25 mol/L. In some embodiments, the concentration of the lithium salt in the electrolyte is about 0.5 mol/L, about 0.6 mol/L, about 0.7 mol/L, about 0.8 mol/L, about 0.9 mol/L, about 1 mol/L, About 1.1mol/L, about 1.25mol/L, 0.5mol/L-1mol/L, or 1mol/L-1.25mol/L, etc.
  • the present application provides an electrolyte that may include a compound of formula I, which can effectively improve the high-temperature cycle performance and high-rate discharge performance of the electrochemical device, and effectively reduce the internal resistance.
  • the present application also provides an electrolyte that may include a compound of formula I and lithium difluorophosphate.
  • the synergistic effect of the two can further improve the high-temperature cycle performance of the electrochemical device and reduce the performance of the electrochemical device. impedance.
  • the present application also provides an electrolyte that may include a compound of formula I, lithium difluorophosphate, and a nitrile compound.
  • the three work together to further improve the high-temperature cycle and storage performance of the electrochemical device.
  • the present application also provides an electrolyte solution that may include a compound of formula I, lithium difluorophosphate, a nitrile compound, and a phosphate compound.
  • the four of them work together to further improve the high-temperature cycle of the electrochemical device. Performance, high-rate discharge performance and hot box performance, and effectively reduce internal resistance.
  • the embodiments of the present application also provide an electrochemical device, which includes a positive electrode, a negative electrode, a separator, and the electrolyte of the present application.
  • the electrochemical device of the present application may include any device that undergoes an electrochemical reaction, and specific examples thereof include all kinds of primary batteries, secondary batteries, fuel cells, solar cells, or capacitors.
  • the electrochemical device is a lithium secondary battery, including a lithium metal secondary battery, a lithium ion secondary battery, a lithium polymer secondary battery, or a lithium ion polymer secondary battery.
  • the electrochemical device of the present application includes a positive electrode having a positive electrode active material capable of occluding and releasing metal ions; a negative electrode having a negative electrode active material capable of occluding and releasing metal ions; placed between the positive electrode and the negative electrode The isolation membrane; and the electrolyte of this application.
  • the electrolyte used in the electrochemical device of the present application is any of the above-mentioned electrolytes in the present application.
  • the electrolytic solution used in the electrochemical device of the present application may also include other electrolytic solutions within the scope not departing from the gist of the present application.
  • the positive electrode includes a positive electrode active material
  • the content of the compound of formula I in the electrolyte is 0.025 g-0.35 g per gram of the positive electrode active material.
  • the content of the compound of formula I in the electrolyte is about 0.025g, about 0.05g, about 0.1g, about 0.1.5g, about 0.2g, about 0.25g, about 0.3 g, about 0.35g, 0.025g-0.1g, 0.1g-0.25g, 0.1g-0.35g or 0.2g-0.35g, etc.
  • the positive electrode includes a current collector and a positive active material layer on the current collector, and the positive active material layer includes a positive active material.
  • the positive electrode active material includes at least one lithiated intercalation compound that reversibly intercalates and deintercalates lithium ions.
  • the positive active material includes a composite oxide.
  • the composite oxide contains lithium and at least one element selected from cobalt, manganese, and nickel.
  • the positive electrode active material is selected from lithium cobalt oxide, lithium nickel cobalt manganese (NCM) ternary material, lithium iron phosphate (LiFePO 4 ), lithium manganate (LiMn 2 O 4 ), or any combination thereof.
  • the positive electrode active material is a mixture of lithium cobalt oxide and lithium nickel manganese cobalt ternary material, wherein lithium cobalt oxide: lithium nickel manganese cobalt is in the range of 1:9 to 9:1.
  • the lithium cobaltate: lithium nickel manganese cobalt is in the range of 2:8 to 4:6.
  • lithium cobaltate and lithium nickel manganese cobalt ternary material as the positive electrode active material can improve the safety performance of the positive electrode active material.
  • lithium cobalt oxide and lithium nickel manganese cobalt ternary materials are mixed to increase the amount of transition metals.
  • the transition metals have a certain catalytic effect on the film formation of the electrolyte, which can make the additives have a more effective film formation effect. .
  • the positive active material may have a coating on its surface, or may be mixed with another compound having a coating.
  • the coating may include at least one selected from the oxide of the coating element, the hydroxide of the coating element, the oxyhydroxide of the coating element, the oxycarbonate of the coating element, and the hydroxycarbonate of the coating element.
  • the compound used for the coating may be amorphous or crystalline.
  • the coating element contained in the coating may include Mg, Al, Co, K, Na, Ca, Si, Ti, V, Sn, Ge, Ga, B, As, Zr, P, or these Any combination of.
  • the coating in the coating layer may be AlPO 4 , Mg 3 (PO 4 ) 2 , Co 3 (PO 4 ) 2 , AlF 3 , MgF 2 , CoF 3 , NaF, B 2 O 3 At least one of them.
  • the content of the coating element in the coating is about 0.01% to about 10%.
  • the coating can be applied by any method as long as the method does not adversely affect the performance of the positive electrode active material.
  • the method may include any coating method known in the art, such as spraying, dipping, and the like.
  • the positive active material layer further includes a binder, and optionally a conductive material.
  • the binder improves the bonding of the positive electrode active material particles to each other, and also improves the bonding of the positive electrode active material to the current collector.
  • the binder includes, but is not limited to: polyvinyl alcohol, hydroxypropyl cellulose, diacetyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, ethylene-containing Oxygen polymers, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, styrene butadiene rubber, acrylic (ester) styrene butadiene rubber, epoxy resin, Nylon etc.
  • conductive materials include, but are not limited to: carbon-based materials, metal-based materials, conductive polymers, and mixtures thereof.
  • the carbon-based material is selected from natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, carbon fiber, or any combination thereof.
  • the metal-based material is selected from metal powder, metal fiber, copper, nickel, aluminum, silver.
  • the conductive polymer is a polyphenylene derivative.
  • the current collector may be, but is not limited to, aluminum.
  • the positive electrode can be prepared by a preparation method known in the art.
  • the positive electrode can be obtained by mixing the active material, the conductive material, and the binder in a solvent to prepare an active material composition, and coating the active material composition on a current collector.
  • the solvent may include, but is not limited to, N-methylpyrrolidone and the like.
  • the positive electrode is made by forming a positive electrode material using a positive electrode active material layer including lithium transition metal-based compound powder and a binder on a current collector.
  • the positive electrode active material layer can usually be made by the following operations: dry mixing the positive electrode active material and the binder (conducting material and thickener used as needed) to form a sheet, The obtained sheet is press-bonded to a positive electrode current collector, or these materials are dissolved or dispersed in a liquid medium to prepare a slurry, which is coated on the positive electrode current collector and dried.
  • the material of the positive active material layer includes any material known in the art.
  • the negative electrode used in the electrochemical device of the present application includes a negative electrode current collector and a negative electrode active material layer.
  • the negative electrode active material layer contains the negative electrode active material.
  • the specific type of the negative electrode active material is not subject to specific restrictions and can be selected according to requirements.
  • the negative electrode active material may be selected from lithium metal, structured lithium metal, natural graphite, artificial graphite, mesophase carbon microspheres (MCMB), hard carbon, soft carbon, silicon, silicon-carbon composite, Li -At least one of Sn alloy, Li-Sn-O alloy, Sn, SnO, SnO 2 , spinel structure lithiated TiO 2 -Li 4 Ti 5 O 12 , and Li-Al alloy.
  • the negative active material is a graphite-based material.
  • the ratio C004/C110 of the peak area of the 004 peak to the peak area of the 110 peak is recorded as the OI value, and the peak area is obtained by integrating the peak intensity and the half-width. Different peak position changes represent the different sizes of graphite unit cells and can reflect the degree of graphitization of graphite materials.
  • the OI value affects the transmission path of lithium ions.
  • the OI value of graphite is 8-15, which can effectively improve the high-temperature cycle performance of the electrochemical device. Moreover, within this range, the smaller the OI value, the more obvious the improvement effect.
  • the electrochemical device of the present application is provided with a separator between the positive electrode and the negative electrode to prevent short circuits.
  • the material and shape of the isolation membrane used in the electrochemical device of the present application are not particularly limited, and it may be any technology disclosed in the prior art.
  • the isolation membrane includes a polymer or an inorganic substance formed of a material that is stable to the electrolyte of the present application.
  • the isolation film may include a substrate layer and a surface treatment layer.
  • the substrate layer is a non-woven fabric, film or composite film with a porous structure, and the material of the substrate layer is selected from at least one of polyethylene, polypropylene, polyethylene terephthalate and polyimide.
  • a polypropylene porous film, a polyethylene porous film, a polypropylene non-woven fabric, a polyethylene non-woven fabric, or a polypropylene-polyethylene-polypropylene porous composite film can be selected.
  • a surface treatment layer is provided on at least one surface of the substrate layer, and the surface treatment layer may be a polymer layer or an inorganic substance layer, or a layer formed by a mixed polymer and an inorganic substance.
  • the inorganic layer includes inorganic particles and a binder.
  • the inorganic particles are selected from alumina, silica, magnesium oxide, titanium oxide, hafnium dioxide, tin oxide, ceria, nickel oxide, zinc oxide, calcium oxide, zirconium oxide, One or a combination of yttrium oxide, silicon carbide, boehmite, aluminum hydroxide, magnesium hydroxide, calcium hydroxide, and barium sulfate.
  • the binder is selected from polyvinylidene fluoride, vinylidene fluoride-hexafluoropropylene copolymer, polyamide, polyacrylonitrile, polyacrylate, polyacrylic acid, polyacrylate, polyvinylpyrrolidone, polyvinyl ether, One or a combination of polymethyl methacrylate, polytetrafluoroethylene and polyhexafluoropropylene.
  • the polymer layer contains a polymer, and the material of the polymer includes polyamide, polyacrylonitrile, acrylate polymer, polyacrylic acid, polyacrylate, polyvinylpyrrolidone, polyvinyl ether, polyvinylidene fluoride or poly( At least one of vinylidene fluoride-hexafluoropropylene).
  • the present application provides a lithium ion battery, which includes the foregoing positive electrode, negative electrode, separator, and electrolyte, and the electrolyte is any one of the foregoing electrolytes in this application.
  • the electrochemical device of the present application has excellent high-temperature cycle performance, high-rate discharge performance, and reduced internal resistance, so that the electrochemical device of the present application is suitable for electronic devices in various fields.
  • the electrochemical device of the present application is not particularly limited, and it can be used for any purpose known in the prior art.
  • the electrochemical device of the present application can be used in, but not limited to, notebook computers, pen-input computers, mobile computers, e-book players, portable phones, portable fax machines, portable copiers, portable printers, and headsets.
  • Isolation membrane A polyethylene porous polymer film with a thickness of 16 ⁇ m is used as the isolation membrane.
  • the electrolytes and lithium ion batteries of the Examples and Comparative Examples were prepared according to the above preparation method; wherein the positive electrode active material was lithium cobalt oxide, the negative electrode active material was graphite, and the lithium ion battery was subjected to high temperature cycle test, high temperature storage test, and DC impedance ( DCR) test, OI value test, hot box test and impact test.
  • the positive electrode active material was lithium cobalt oxide
  • the negative electrode active material was graphite
  • the lithium ion battery was subjected to high temperature cycle test, high temperature storage test, and DC impedance ( DCR) test, OI value test, hot box test and impact test.
  • DCR DC impedance
  • Thickness expansion ratio (H 12 -H 11 )/H 11 *100%.
  • Bruker's X-ray diffraction (XRD) instrument was used to test the OI value of the negative electrode active material, and its XRD was tested in accordance with the general rules of X-ray diffractometer analysis and the test method for lattice parameters of artificial graphite JIS K0131-1996, JB/T 4220-2011.
  • the ratio of the peak area of the 004 peak to the peak area of the 110 peak, C004/C110, is recorded as the OI value, where the peak area is obtained by integrating the peak intensity and the half-width.
  • the lithium-ion battery At room temperature, the lithium-ion battery is charged to a voltage of 4.45V at a constant current of 0.7C, and allowed to stand at room temperature for 60 minutes. Before the test, record the OCV (open circuit voltage) and IMP (impedance) of the lithium-ion battery, check the appearance and take a photo, and take a picture at 3°C. /min ⁇ 2°C/min rate to 135°C ⁇ 2°C, and keep for 60min. Test 5 batteries in each group, and record the number of batteries that pass the test if the sample does not catch fire or explode.
  • OCV open circuit voltage
  • IMP immpedance
  • the charging process is as follows: at room temperature, the lithium-ion battery is charged to a voltage of 4.45V at a constant current of 0.7C, and allowed to stand at room temperature for 60 minutes. Record the OCV and IMP before the test. Check the appearance and take a photo. The diameter is ⁇ 15. A round rod of 8mm and a length of at least 6cm shall be perpendicular to the sample. Use a 9Kg weight at a distance of 61cm from the intersection of the round rod and the sample, and fall vertically and freely. After the test, record the OCV and IMP, check the appearance and take pictures. The sample does not catch fire and does not explode to pass.
  • Table 1 shows the parameters of the electrolytes in Examples 1 to 18 and Comparative Examples 1 and 2.
  • Table 2 shows the electrical performance test results of the lithium ion batteries of Examples 1 to 18 and Comparative Examples 1 and 2.
  • Table 3 shows the parameters of the electrolytes in Examples 19 to 31.
  • Table 4 shows the electrical performance test results of the lithium ion batteries of Examples 19 to 31.
  • Example 33 By comparing Example 33 and Example 34, it can be seen that when the content of the nitrile compound exceeds 10% by weight, when the content of the nitrile compound is increased, the improvement effect of the high temperature cycle performance will be reduced. This is because the high content of the nitrile compound increases the electrolyte. The viscosity deteriorates the kinetics of lithium-ion batteries.
  • Table 5 shows the parameters of the electrolytes in Examples 35 to 44.
  • Table 6 shows the electrical performance test results of the lithium ion batteries of Examples 35 to 44.
  • Example 39 By comparing Examples 39 to 43 with Example 44, it can be seen that when the content of the phosphate compound in the electrolyte exceeds 10% by weight, as the content of the phosphate compound (for example, formula V-2) increases, the high temperature of the lithium ion battery The worse the cycle performance is. This is mainly because the viscosity of the phosphate compound is relatively large. Excessive content of the phosphate compound will deteriorate the conductivity of the electrolyte; at the same time, due to its higher reduction potential, there is also a serious deterioration in the negative electrode, causing risks such as lithium evolution. , Therefore, it will seriously affect the kinetics of lithium-ion batteries and limit their applications.
  • Table 7 shows the positive and negative electrode parameters of Examples 45 to 51 and the electrical performance test results of the lithium ion battery.
  • the electrolytes of Examples 45 to 51 are the same as that of Example 22, and the amount of the compound of formula I per gram of the positive electrode active material is obtained by adjusting the weight of the positive electrode active material.
  • the OI value of the negative electrode active material in the range of 8-15 can effectively improve the high temperature cycle performance of the lithium ion battery, and within this range, the smaller the OI value, the improvement The more obvious the effect. This is because the smaller the OI value, the more the pressure surface of the negative electrode in the process of pressure, the more the direction of the force, and the more uniform the force. During the cycle of lithium-ion batteries, due to the increase of the pressure surface, the stress generated between the graphite layers when lithium ions are inserted or extracted can be suppressed or offset, thereby greatly improving the high-temperature cycle.
  • references to “some embodiments”, “partial embodiments”, “one embodiment”, “another example”, “examples”, “specific examples” or “partial examples” throughout the specification mean At least one embodiment or example in this application includes the specific feature, structure, material, or characteristic described in the embodiment or example. Therefore, descriptions appearing in various places throughout the specification, such as: “in some embodiments”, “in embodiments”, “in one embodiment”, “in another example”, “in an example “In”, “in a specific example” or “exemplified”, which are not necessarily quoting the same embodiment or example in this application.
  • the specific features, structures, materials, or characteristics herein can be combined in one or more embodiments or examples in any suitable manner.

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Abstract

本申请涉及一种电解液和包括电解液的电化学装置及电子装置。所述电解液包含含有两性离子的内盐型化合物，可以有效改善电化学装置的高温循环性能和大倍率放电性能，并且降低电化学装置的内阻。

Description

电解液和包括电解液的电化学装置及电子装置 技术领域
本申请涉及储能技术领域，尤其涉及电解液和包括电解液的电化学装置及电子装置。
背景技术
电化学装置，如锂二次电池具有工作电压高、比能量密度大、循环寿命长、自放电率低、无记忆效应以及环境污染小等优点，已经广泛应用于各类电子消费品市场，它也是未来电动车辆和各种电动工具的理想动力源。
电解液是锂二次电池的重要组成部分。磺酸酯类添加剂包括丙磺酸内酯、丙烯磺酸内酯、丁磺酸内酯或亚硫酸酯等，在目前商品电解液中被广泛应用，它不仅能改善锂离子电池高温下的存储及循环性能，而且对抑制电池胀气方面也体现出良好的效果。但是目前应用最为广泛且综合性能最佳的丙磺酸内酯具有致癌特性，已被欧盟列为重点关注物质，因此开发出综合性能更优的磺酸酯替代产品成为目前行业亟待解决的技术问题。
发明内容
本申请提供一种电解液及包括电解液的电化学装置以试图在至少某种程度上解决至少一个存在于相关领域中的问题。
本申请提供了一种包含具有两性离子的内盐性化合物的电解液，所述内盐性化合物不仅不会对人体产生危害，而且可以有效改善电化学装置的高温循环性能和大倍率放电性能，并有效地降低内阻。
根据本申请的实施例，本申请提供了一种电解液，其包含式I化合物
Figure PCTCN2020093220-appb-000001
其中R 1选自卤素原子、取代或未取代的C 1至C 10烷基、取代或未取代的C 2至C 10直链或支链烯基、取代或未取代的C 2至C 10直链或支链炔基，其中经取代时，取代基为卤素原子；其中R 2选自取代或未取代的C 1至C 6亚烷基或取代或未取代的C 2至C 6亚烯基，其中经取代时，取代基为卤素原子；其中X选自-S(＝O)O、-O-S(＝O)O、-S(＝O) 2O、-O-S(＝O) 2O、-C(＝O)O、-O-C(＝O)O、-PO 3H、-OPO 3H或-BO 2H；其中A选自亚甲基或氧原子。
根据本申请的实施例，所述式I化合物包含：
Figure PCTCN2020093220-appb-000002
Figure PCTCN2020093220-appb-000003
中的至少一种。
根据本申请的实施例，基于所述电解液的重量，所述式I化合物的含量为0.05wt％-3.5wt％。
根据本申请的实施例，所述电解液还包括二氟磷酸锂，基于所述电解液的重量，所述二氟磷酸锂的含量小于1wt％。
根据本申请的实施例，基于所述电解液的重量，所述式I化合物的含量a％与所述二氟磷酸锂的含量b％满足a+b<4.5且a/b>1:10。
根据本申请的实施例，所述电解液还包含腈化合物，所述腈化合物包含式II、式III或式IV所示的化合物中的至少一种：
Figure PCTCN2020093220-appb-000004
其中，R 21选自取代或未取代的C 1至C 10亚烷基、取代或未取代的C 2至C 10亚烯基或含有至少一个醚键的C 2至C 6直链或支链的亚烷基或亚烯基，其中经取代时，取代基为卤素原子、硝基、氰基、羧基或硫酸基中的至少一种；其中R 31、R 32、R 33各自独立地选自单键、取代或未取代的C 1至C 10亚烷基或含有至少一个醚键的C 2至C 6直链或支链的亚烷基或亚烯基，其中经取代时，取代基为卤素原子、硝基、氰基、羧基或硫酸基中的至少一种；其中R 41选自取代或未取代的C 1至C 10亚烷基、取代或未取代的C 2至C 10亚烯基、取代或未取代的C 6至C 10亚芳基、取代或未取代的C 3至C 6亚环烷基或取代或未取代的C 6至C 10杂环基团，其中经取代时，取代基为卤素原子、硝基、氰基、羧基或硫酸基中的至少一种，其中所述杂环基团包含O、S、N或P中的至少一种；其中基于所述电解液的重量，所述腈化合物的含量为0.5wt％-10wt％。
根据本申请的实施例，腈化合物包含
Figure PCTCN2020093220-appb-000005
Figure PCTCN2020093220-appb-000006
Figure PCTCN2020093220-appb-000007
中的至少一种。
根据本申请的实施例，电解液还包含磷酸酯化合物，所述磷酸酯化合物包含式V化合物
Figure PCTCN2020093220-appb-000008
其中R 51、R 52、R 53各自独立地选自氢、取代或未取代的C 1至C 5烷基、取代或未取代的C 2至C 10烯基、取代或未取代的C 6至C 10芳基或取代或未取代的C 1至C 6的杂环基团，其中经取代时，取代基为卤素原子、硝基、氰基、羧基、硫酸基、磷酸酯基或硅烷基中的至少一种；其中基于所述电解液的重量，所述磷酸酯化合物的含量为0.1wt％-10wt％。
根据本申请的实施例，磷酸酯化合物包含
Figure PCTCN2020093220-appb-000009
Figure PCTCN2020093220-appb-000010
Figure PCTCN2020093220-appb-000011
中的至少一种。
根据本申请的实施例，所述电解液包含非水有机溶剂，其中所述非水有机溶剂包括碳酸乙烯酯、碳酸丙烯酯、碳酸二甲酯、碳酸二乙酯、碳酸甲乙酯、γ-丁内酯、乙酸甲酯、乙酸乙酯、乙酸丙酯、乙酸丁酯、丙酸甲酯、丙酸乙酯、丙酸丙酯、丙酸丁酯、丁酸甲酯、丁酸乙酯或丁酸丙酯中的至少一种。
根据本申请的实施例，本申请还提供了一种电化学装置，其包括正极、负极、隔离膜和如上所述的任一种电解液。
根据本申请的实施例，在所述电化学装置中，所述负极包括负极活性材料，所述负极活性材料的OI值为8-15。
根据本申请的实施例，在所述电化学装置中，所述正极包括正极活性材料，基于每克所述正极活性材料，电解液中的式I化合物的含量为0.025g-0.35g。
根据本申请的实施例，本申请还提供了一种电子装置，其包括如上所述的任一种电化学装置。
本申请实施例的额外层面及优点将部分地在后续说明中描述、显示、或是经由本申请实施例的实施而阐释。
附图说明
在下文中将简要地说明为了描述本申请实施例或现有技术所必要的附图以便于描 述本申请的实施例。显而易见地，下文描述中的附图仅只是本申请中的部分实施例。对本领域技术人员而言，在不需要创造性劳动的前提下，依然可以根据这些附图中所例示的结构来获得其他实施例的附图。
图1为式I-1化合物的 1H NMR光谱图(溶剂：D 2O)。
具体实施方式
本申请的实施例将会被详细的描示在下文中。在本申请说明书全文中，将相同或相似的组件以及具有相同或相似的功能的组件通过类似附图标记来表示。在此所描述的有关附图的实施例为说明性质的、图解性质的且用于提供对本申请的基本理解。本申请的实施例不应该被解释为对本申请的限制。
如本文中所使用，术语“大致”、“大体上”、“实质”及“约”用以描述及说明小的变化。当与事件或情形结合使用时，所述术语可指代其中事件或情形精确发生的例子以及其中事件或情形极近似地发生的例子。举例来说，当结合数值使用时，术语可指代小于或等于所述数值的±10％的变化范围，例如小于或等于±5％、小于或等于±4％、小于或等于±3％、小于或等于±2％、小于或等于±1％、小于或等于±0.5％、小于或等于±0.1％、或小于或等于±0.05％。举例来说，如果两个数值之间的差值小于或等于所述值的平均值的±10％(例如小于或等于±5％、小于或等于±4％、小于或等于±3％、小于或等于±2％、小于或等于±1％、小于或等于±0.5％、小于或等于±0.1％、或小于或等于±0.05％)，那么可认为所述两个数值“大体上”相同。
另外，有时在本文中以范围格式呈现量、比率和其它数值。应理解，此类范围格式是用于便利及简洁起见，且应灵活地理解，不仅包含明确地指定为范围限制的数值，而且包含涵盖于所述范围内的所有个别数值或子范围，如同明确地指定每一数值及子范围一般。
在具体实施方式及权利要求书中，由术语“中的至少一者”、“中的至少一个”、“中的至少一种”或其他相似术语所连接的项目的列表可意味着所列项目的任何组合。例如，如果列出项目A及B，那么短语“A及B中的至少一者”意味着仅A；仅B；或A及B。在另一实例中，如果列出项目A、B及C，那么短语“A、B及C中的至少一者”意味着仅A；或仅B；仅C；A及B(排除C)；A及C(排除B)；B及C(排除A)；或A、B及C的全部。项目A可包含单个组分或多个组分。项目B可包含单个组分或 多个组分。项目C可包含单个组分或多个组分。
术语“烷基”预期是具有1至20个碳原子的直链饱和烃结构。“烷基”还预期是具有3至20个碳原子的支链或环状烃结构。例如，烷基可为1至20个碳原子的烷基、1至10个碳原子的烷基、1至5个碳原子的烷基、5至20个碳原子的烷基、5至15个碳原子的烷基或5至10个碳原子的烷基。当指定具有具体碳数的烷基时，预期涵盖具有该碳数的所有几何异构体；因此，例如，“丁基”意思是包括正丁基、仲丁基、异丁基、叔丁基和环丁基；“丙基”包括正丙基、异丙基和环丙基。烷基实例包括，但不限于甲基、乙基、正丙基、异丙基、环丙基、正丁基、异丁基、仲丁基、叔丁基、环丁基、正戊基、异戊基、新戊基、环戊基、甲基环戊基、乙基环戊基、正己基、异己基、环己基、正庚基、辛基、环丙基、环丁基、降冰片基等。另外，烷基可以是任选地被取代的。
术语“亚烷基”单独地或作为另一个取代基的一部分意指衍生自烷基的二价自由基。
术语“烯基”是指可为直链或具支链且具有至少一个且通常1个、2个或3个碳碳双键的单价不饱和烃基团。除非另有定义，否则所述烯基通常含有2至20个碳原子，例如可以为2至20个碳原子的烯基、6至20个碳原子的烯基、2至10个碳原子的烯基或2～6个碳原子的烯基。代表性烯基包括(例如)乙烯基、正丙烯基、异丙烯基、正-丁-2-烯基、丁-3-烯基、正-己-3-烯基等。另外，烯基可以是任选地被取代的。
术语“亚烯基”涵盖直链和支链亚烯基。当指定具有具体碳数的亚烯基时，预期涵盖具有该碳数的所有几何异构体。例如，亚烯基可为2至20个碳原子的亚烯基、2至15个碳原子的亚烯基、2至10个碳原子的亚烯基、2至5个碳原子的亚烯基，5至20个碳原子的亚烯基、5至15个碳原子的亚烯基、或5至10个碳原子的亚烯基。代表性亚烷基包括(例如)亚乙烯基、亚丙烯基、亚丁烯基等。另外，亚烯基可以是任选地被取代的。
术语“炔基”是指可为直链或具支链且具有至少一个且通常具有1个、2个或3个碳碳三键的单价不饱和烃基团。除非另有定义，否则所述炔基通常含有2至20个碳原子，例如可以为2至20个碳原子的炔基、6至20个碳原子的炔基、2至10个碳原子的炔基或2至6个碳原子的炔基。代表性炔基包括(例如)乙炔基、丙-2-炔基(正-丙炔基)、正-丁-2-炔基、正-己-3-炔基等。另外，炔基可以是任选地被取代的。
术语“芳基”涵盖单环系统和多环系统。多环可以具有其中两个碳为两个邻接环(所述环是“稠合的”)共用的两个或更多个环，其中所述环中的至少一者是芳香族的，例如其 它环可以是环烷基、环烯基、芳基、杂环和/或杂芳基。例如，芳基可为C 6至C 50芳基、C 6至C 40芳基、C 6至C 30芳基、C 6至C 20芳基或C 6至C 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。另外，芳基可以是任选地被取代的。
术语“亚芳基”单独地或作为另一个取代基的一部分意指衍生自芳基的二价自由基。
术语“杂环基团”涵盖芳香族和非芳香族环状基团。杂芳香族环状基团还意指杂芳基。在一些实施例中，杂芳香族环基团和杂非芳香族环基团为包括至少一个杂原子的C 1至C 50杂环基、C 1至C 40杂环基、C 1至C 30杂环基、C 1至C 20杂环基、C 1至C 10杂环基、C 1至C 6杂环基。例如吗啉基、哌啶基、吡咯烷基等，以及环醚，例如四氢呋喃、四氢吡喃等。杂原子涵盖O、S、P、N、B或其电子等排体。另外，杂环基团可以是任选地被取代的。
如本文所用，“硅烷基”预期是衍生自硅烷的自由基，例如-SiH 3或-Si(CH 3) 3等。
如本文所用，术语“卤素”可为F、Cl、Br或I。
本申请的实施例提供了电解液和包括电解液的电化学装置及电子装置。在一些实施例中，所述电化学装置为锂离子电池。
一、电解液
本申请的实施例提供了一种电解液，其包括有机溶剂、电解质和添加剂，所述添加剂包括式I化合物。在一些实施例中，所述电解液是非水电解液
式I化合物
在一些实施例中，电解液包含式I化合物
Figure PCTCN2020093220-appb-000012
在式I中，R 1选自卤素原子、取代或未取代的C 1至C 10烷基、取代或未取代的C 2至C 10直链或支链烯基、取代或未取代的C 2至C 10直链或支链炔基，其中经取代时，取代基为卤素原子；其中R 2选自取代或未取代的C 1至C 6亚烷基或取代或未取代的C 2至 C 6亚烯基，其中经取代时，取代基为卤素原子；其中X选自-S(＝O)O、-O-S(＝O)O、-S(＝O) 2O、-O-S(＝O) 2O、-C(＝O)O、-O-C(＝O)O、-PO 3H、-OPO 3H或-BO 2H；其中A选自亚甲基或氧原子。
在一些实施例中，所述式I化合物包含：
Figure PCTCN2020093220-appb-000013
Figure PCTCN2020093220-appb-000014
中的至少一种。
上述所述式I化合物可以通过各自对应的胺与磺酸内酯发生开环反应合成。开环反应可在空气中进行，优选在干燥气氛中，例如在干燥空气、氮气或氩气中。如上所述的式I化合物的反应一般是在-5℃与30℃之间，优选是0℃至室温。例如，以式I-1化合物(3-(1-甲基哌啶烷鎓-1-基)丙烷-1-磺酸盐)为例，合成式I-1化合物的反应式如下：
Figure PCTCN2020093220-appb-000015
在0℃、氩气氛围下，将20mL甲苯中的9.9g N-甲基哌啶逐滴滴加到溶于60mL甲苯的13.4g 1,3-丙烷磺酸内酯中，冰水浴下反应1h，转至室温下搅拌反应过夜。通过过滤分离沉淀物、用甲苯清洗滤饼两次且在40℃减压下干燥24h，获得16.2g白色粉末状固体，即，式I-1化合物。式I-1化合物的产率为73％。
通过NMR光谱表征式I的化合物。在装配有9.3980T低温磁铁的Bruker Avance Ⅲ 光谱仪中在25℃下于5mm NMR管中测量NMR样本。使用在400.17和376.54MHz下操作的5mm组合式 1H测量头来测量 1H NMR光谱。 13C NMR光谱通过使用在100.62MHz下的5mm宽带反向测量头来获得。在 1H NMR光谱情况中的参考物是四甲基硅烷(TMS)，其使用溶剂重水D 2O(4.80ppm)的化学位移(δ)。
图1是式I-1的 1H NMR光谱图(溶剂：D 2O)，图中的1-7表示第1峰至第7峰，其中第1峰至第7峰的δ(ppm)分别是：3.39(m，2H)、3.28(m，4H)、2.94(s，3H)2.87(t，2H)、2.11(m，2H)、1.77(m，4H)、1.55(m，2H)。
式I化合物是一种含两性离子的内盐性化合物，不会对人体产生危害，而且可以提高锂盐的解离度，增加电解液的电导率，并且可以显著提升大倍率放电性能，有效降低电化学装置内阻；同时由于内盐性化合物具有磺酸酯结构，在正负极表面在负极和正极表面有利于形成更稳定的钝化膜，具体体现于电化学装置在高温下具有良好的循环性能和存储性能。
在一些实施例中，基于电解液的重量，式I化合物的含量为0.05wt％-3.5wt％。在一些实施例中，基于电解液的重量，式I化合物的含量为约0.1wt％、约0.2wt％、约0.3wt％、约0.4wt％、约0.5wt％、约0.7wt％、约1wt％、约1.5wt％、约2wt％、约2.5wt％、约3wt％、0.1wt％-0.5wt％、0.1wt％-1wt％、0.5wt％-1wt％、1wt％-2wt％、2wt％-3wt％、1wt％-3wt％或1wt％-3.5wt％等。
二氟磷酸锂
在一些实施例中，除了式I化合物，电解液还可以包括二氟磷酸锂(LiPO 2F 2)。加入二氟磷酸锂，可以进一步增加有机保护膜当中LiF的成份，使电解液的稳定性会增加，从而起到改善循环、降低电化学装置的阻抗的效果。
在一些实施例中，基于电解液的重量，二氟磷酸锂的含量小于约1wt％。在一些实施例中，基于电解液的重量，二氟磷酸锂的含量小于约0.05wt％、约0.1wt％、约0.2wt％、约0.3wt％、约0.4wt％、约0.5wt％、约0.6wt％、约0.7wt％、约0.8wt％、约0.9wt％或约1wt％等。
在一些实施例中，基于电解液的重量，式I化合物的含量a％与所述二氟磷酸锂的含量b％满足a+b<4.5且a/b>1:10。当a+b≥4.5时，因添加剂加入量加多，会影响锂离子的传输，会恶化电化学装置的性能；当a/b≤1/10时，因式I化合物的添加量较少而起不到明显的改善效果。
腈化合物
在一些实施例中，电解液还包含腈化合物，所述腈化合物包含式II、式III或式IV所示的至少一种：
Figure PCTCN2020093220-appb-000016
在式II中，R 21选自取代或未取代的C 1至C 10亚烷基、取代或未取代的C 2至C 10亚烯基或含有至少一个醚键的C 2至C 6直链或支链的亚烷基或亚烯基，其中经取代时，取代基为卤素原子、硝基、氰基、羧基或硫酸基中的至少一种。
在式III中，R 31、R 32、R 33各自独立地选自单键、取代或未取代的C 1至C 10亚烷基或含有至少一个醚键的C 2至C 6直链或支链的亚烷基或亚烯基，其中经取代时，取代基为卤素原子、硝基、氰基、羧基或硫酸基中的至少一种。
在式IV中，R 41选自取代或未取代的C 1至C 10亚烷基、取代或未取代的C 2至C 10亚烯基、取代或未取代的C 6至C 10亚芳基、取代或未取代的C 3至C 6亚环烷基或取代或未取代的C 6至C 10杂环基团，其中经取代时，取代基为卤素原子、硝基、氰基、羧基或硫酸基中的至少一种，其中所述杂环基团包含O、S、N或P中的至少一种。
在一些实施例中，腈化合物包含
Figure PCTCN2020093220-appb-000017
Figure PCTCN2020093220-appb-000018
Figure PCTCN2020093220-appb-000019
中的至少一种。
腈化合物与式I化合物共同作用可以进一步改善正负极表面的保护膜，降低正负极与电解液的副反应，从而改善电化学装置的循环性能和高温存储性能。
在一些实施例中，基于电解液的重量，腈化合物的含量为0.5wt％-10wt％对电化学装置性能的改善较明显，能使电化学装置得到更好循环性能和高温存储性能。
在一些实施例中，基于电解液的重量，腈化合物的含量为约0.5wt％、约1wt％、约1.5wt％、约2wt％、约2.5wt％、约3wt％、约3.5wt％、约4wt％、约4.5wt％、约5wt％、约5.5wt％、约6wt％、约7wt％、约8wt％、约9wt％、约10wt％、0.5wt％-1wt％、0.5wt％-2wt％、0.5wt％-3wt％、1wt％-3wt％、1wt％-6wt％、1.5wt％-5wt％、1.5wt％-6wt％、2wt％-5wt％、3wt％-6wt％或5wt％-10wt％等。
磷酸酯化合物
在一些实施例中，本申请的电解液还可以包含磷酸酯化合物，所述磷酸酯化合物包含式V化合物
Figure PCTCN2020093220-appb-000020
在式V中，R 51、R 52、R 53各自独立地选自氢、取代或未取代的C 1至C 5烷基、取代或未取代的C 2至C 10烯基、取代或未取代的C 6至C 10芳基或取代或未取代的C 1至C 6的杂环基团，其中经取代时，取代基为卤素原子、硝基、氰基、羧基、硫酸基、磷酸酯基或硅烷基中的至少一种。
在一些实施例中，磷酸酯化合物包含
Figure PCTCN2020093220-appb-000021
Figure PCTCN2020093220-appb-000022
中的至少一种。
磷酸酯化合物与式I化合物共同作用，可进一步提升电化学装置的热稳定性，防止电化学装置热失控。
在一些实施例中，基于电解液的重量，磷酸酯化合物的含量为0.1wt％-10wt％。当 磷酸酯化合物的含量在此范围内成膜效果更明显，能够得到更优异的保护膜。在一些实施例中，基于电解液的重量，磷酸酯化合物的含量为约0.1wt％、约0.5wt％、约1wt％、约2wt％、约3wt％、约5wt％、约6wt％、约7wt％、约8wt％、约9wt％、约10wt％、0.1wt％-1wt％、0.5wt％-1wt％、0.1wt％-5wt％、1wt％-5wt％、1wt％-10wt％或5wt％-10wt％等。
在一些实施例中，电解液还包含非水有机溶剂，其中所述非水有机溶剂包括碳酸乙烯酯、碳酸丙烯酯、碳酸二甲酯、碳酸二乙酯、碳酸甲乙酯、γ-丁内酯、乙酸甲酯、乙酸乙酯、乙酸丙酯、乙酸丁酯、丙酸甲酯、丙酸乙酯、丙酸丙酯、丙酸丁酯、丁酸甲酯、丁酸乙酯或丁酸丙酯中的至少一种。
在一些实施例中，电解液还包含锂盐，所述锂盐选自六氟磷酸锂(LiPF 6)、双三氟甲烷磺酰亚胺锂(LiN(CF 3SO 2) 2)、双(氟磺酰)亚胺锂(LiN(SO 2F) 2))、双草酸硼酸锂(LiB(C 2O 4) 2)、四氟磷酸草酸锂(LiPF 4C 2O 2)、二氟草酸硼酸锂(LiBF 2(C 2O 4))或六氟铯酸锂(LiCsF 6)的至少一种。在一些实施例中，锂盐在电解液中的浓度为0.5mol/L-1.25mol/L。在一些实施例中，锂盐在电解液中的浓度为约0.5mol/L、约0.6mol/L、约0.7mol/L、约0.8mol/L、约0.9mol/L、约1mol/L、约1.1mol/L、约1.25mol/L、0.5mol/L-1mol/L或1mol/L-1.25mol/L等。
根据本申请的实施例，本申请提供了一种可以包括式I化合物的电解液，可以有效改善电化学装置的高温循环性能和大倍率放电性能，并有效地降低内阻。
根据本申请的实施例，本申请还提供了一种可以包括式I化合物和二氟磷酸锂的电解液，利用两者的协同作用，进一步改善电化学装置的高温循环性能和降低电化学装置的阻抗。
根据本申请的实施例，本申请还提供了一种可以包括式I化合物、二氟磷酸锂和腈化合物的电解液，三者共同作用，可以进一步改善电化学装置的高温循环和存储性能。
根据本申请的实施例，本申请还提供了一种可以包括式I化合物、二氟磷酸锂、腈化合物和磷酸酯化合物的电解液，这四者共同作用，可以进一步改善电化学装置的高温循环性能、大倍率放电性能和热箱性能，并有效地降低内阻。
二、电化学装置
本申请的实施例还提供了一种电化学装置，其包括正极、负极、隔离膜和本申请的电解液。本申请的电化学装置可以包括发生电化学反应的任何装置，它的具体实例包括所有种类的一次电池、二次电池、燃料电池、太阳能电池或电容。特别地，该电化学装 置是锂二次电池，包括锂金属二次电池、锂离子二次电池、锂聚合物二次电池或锂离子聚合物二次电池。在一些实施例中，本申请的电化学装置包括具有能够吸留、放出金属离子的正极活性材料的正极；具有能够吸留、放出金属离子的负极活性材料的负极；置于正极和负极之间的隔离膜；以及本申请的电解液。
电解液
本申请的电化学装置中使用的电解液为本申请的上述任何电解液。此外，本申请的电化学装置中使用的电解液还可包含不脱离本申请的主旨的范围内的其它电解液。
正极
在一些实施例中，正极包括正极活性材料，基于每克所述正极活性材料，电解液中的式I化合物的含量为0.025g-0.35g。在一些实施例中，基于每克正极活性材料，电解液中的式I化合物的含量为约0.025g、约0.05g、约0.1g、约0.1.5g、约0.2g、约0.25g、约0.3g、约0.35g、0.025g-0.1g、0.1g-0.25g、0.1g-0.35g或0.2g-0.35g等。
在一些实施例中，正极包括集流体和位于该集流体上的正极活性材料层，正极活性材料层包括正极活性材料。正极活性材料包括可逆地嵌入和脱嵌锂离子的至少一种锂化插层化合物。在一些实施例中，正极活性材料包括复合氧化物。在一些实施例中，该复合氧化物含有锂以及从钴、锰和镍中选择的至少一种元素。
在一些实施例中，正极活性材料选自钴酸锂、锂镍钴锰(NCM)三元材料、磷酸亚铁锂(LiFePO 4)、锰酸锂(LiMn 2O 4)或它们的任意组合。在一些实施例中，正极活性材料是钴酸锂与锂镍锰钴三元材料的混合物，其中钴酸锂:锂镍锰钴在1:9至9:1的范围。在一些实施例中，钴酸锂:锂镍锰钴在2:8至4:6。使用钴酸锂与锂镍锰钴三元材料的混合物作为正极活性材料可以提高正极活性材料的安全性能。与此同时，钴酸锂与锂镍锰钴三元材料混合之后增加了过渡金属的数量，过渡金属对电解液的成膜起到一定的催化作用，可以让添加剂起到更加有效的成膜效果。
在一些实施例中，正极活性材料可以在其表面上具有涂层，或者可以与具有涂层的另一化合物混合。该涂层可以包括从涂覆元素的氧化物、涂覆元素的氢氧化物、涂覆元素的羟基氧化物、涂覆元素的碳酸氧盐和涂覆元素的羟基碳酸盐中选择的至少一种涂覆元素化合物。用于涂层的化合物可以是非晶的或结晶的。
在一些实施例中，在涂层中含有的涂覆元素可以包括Mg、Al、Co、K、Na、Ca、Si、Ti、V、Sn、Ge、Ga、B、As、Zr、P或它们的任意组合。在一些实施例中，涂覆层 中的涂覆物可以为AlPO 4、Mg 3(PO 4) 2、Co 3(PO 4) 2、AlF 3、MgF 2、CoF 3、NaF、B 2O 3中的至少一种。在一些实施例中，基于正极活性材料的重量计，涂层中的涂覆元素的含量为约0.01％-约10％。可以通过任何方法来施加涂层，只要该方法不对正极活性材料的性能产生不利影响即可。例如，该方法可以包括对本领域公知的任何涂覆方法，例如喷涂、浸渍等。
正极活性材料层还包括粘合剂，并且可选地包括导电材料。粘合剂提高正极活性材料颗粒彼此间的结合，并且还提高正极活性材料与集流体的结合。
在一些实施例中，粘合剂包括，但不限于：聚乙烯醇、羟丙基纤维素、二乙酰基纤维素、聚氯乙烯、羧化的聚氯乙烯、聚氟乙烯、含亚乙基氧的聚合物、聚乙烯吡咯烷酮、聚氨酯、聚四氟乙烯、聚偏1,1-二氟乙烯、聚乙烯、聚丙烯、丁苯橡胶、丙烯酸(酯)化的丁苯橡胶、环氧树脂、尼龙等。
在一些实施例中，导电材料包括，但不限于：基于碳的材料、基于金属的材料、导电聚合物和它们的混合物。在一些实施例中，基于碳的材料选自天然石墨、人造石墨、碳黑、乙炔黑、科琴黑、碳纤维或其任意组合。在一些实施例中，基于金属的材料选自金属粉、金属纤维、铜、镍、铝、银。在一些实施例中，导电聚合物为聚亚苯基衍生物。
在一些实施例中，集流体可以是，但不限于，铝。
正极可以通过本领域公知的制备方法制备。例如，正极可以通过如下方法获得：在溶剂中将活性材料、导电材料和粘合剂混合，以制备活性材料组合物，并将该活性材料组合物涂覆在集流体上。在一些实施例中，溶剂可以包括，但不限于，N-甲基吡咯烷酮等。
在一些实施例中，正极通过在集流体上使用包括锂过渡金属系化合物粉体和粘结剂的正极活性材料层形成正极材料而制成。
在一些实施例中，正极活性材料层通常可以通过如下操作来制作：将正极活性材料和粘结剂(根据需要而使用的导电材料和增稠剂等)进行干式混合而制成片状，将得到的片压接于正极集流体，或者使这些材料溶解或分散于液体介质中而制成浆料状，涂布在正极集流体上并进行干燥。在一些实施例中，正极活性材料层的材料包括任何本领域公知的材料。
负极
本申请的电化学装置中使用的负极包括负极集流体和负极活性材料层，负极活性材料层包含负极活性材料，负极活性材料的具体种类均不受到具体的限制，可根据需求进行选择。具体地，所述负极活性材料可以选自锂金属、结构化的锂金属、天然石墨、人造石墨、中间相微碳球(MCMB)、硬碳、软碳、硅、硅-碳复合物、Li-Sn合金、Li-Sn-O合金、Sn、SnO、SnO 2、尖晶石结构的锂化TiO 2-Li 4Ti 5O 12、Li-Al合金中的至少一种。
在一些实施例中，负极活性材料是石墨类材料。关于石墨类材料，004峰的峰面积与110峰的峰面积的比值C004/C110记为OI值，峰面积为峰强与半峰宽积分得到。不同的峰位变化，代表了石墨晶胞大小的不同，能够反映出石墨类材料的石墨化程度。OI值影响锂离子的传输路径。在一些实施例中，石墨的OI值为8-15，能够有效改善电化学装置的高温循环性能。并且，在此范围内，OI值越小，其改善效果越明显，这是由于OI值越小，负极在受压过程中，受压面越多，受力的方向增多，受力更加均匀。在锂离子电池循环过程中，由于受压面增多，锂离子嵌入或脱出时石墨层间所产生的应力能够得到抑制或抵消，从而大大改善高温循环。
隔离膜
在一些实施例中，本申请的电化学装置在正极与负极之间设有隔离膜以防止短路。本申请的电化学装置中使用的隔离膜的材料和形状没有特别限制，其可为任何现有技术中公开的技术。在一些实施例中，隔离膜包括由对本申请的电解液稳定的材料形成的聚合物或无机物等。
例如，隔离膜可包括基材层和表面处理层。基材层为具有多孔结构的无纺布、膜或复合膜，基材层的材料选自聚乙烯、聚丙烯、聚对苯二甲酸乙二醇酯和聚酰亚胺中的至少一种。具体的，可选用聚丙烯多孔膜、聚乙烯多孔膜、聚丙烯无纺布、聚乙烯无纺布或聚丙烯-聚乙烯-聚丙烯多孔复合膜。
基材层的至少一个表面上设置有表面处理层，表面处理层可以是聚合物层或无机物层，也可以是混合聚合物与无机物所形成的层。
无机物层包括无机颗粒和粘结剂，无机颗粒选自氧化铝、氧化硅、氧化镁、氧化钛、二氧化铪、氧化锡、二氧化铈、氧化镍、氧化锌、氧化钙、氧化锆、氧化钇、碳化硅、勃姆石、氢氧化铝、氢氧化镁、氢氧化钙和硫酸钡中的一种或几种的组合。粘结剂选自聚偏氟乙烯、偏氟乙烯-六氟丙烯的共聚物、聚酰胺、聚丙烯腈、聚丙烯酸酯、聚丙烯酸、聚丙烯酸盐、聚乙烯呲咯烷酮、聚乙烯醚、聚甲基丙烯酸甲酯、聚四氟乙烯和聚六氟丙 烯中的一种或几种的组合。聚合物层中包含聚合物，聚合物的材料包括聚酰胺、聚丙烯腈、丙烯酸酯聚合物、聚丙烯酸、聚丙烯酸盐、聚乙烯呲咯烷酮、聚乙烯醚、聚偏氟乙烯或聚(偏氟乙烯-六氟丙烯)中的至少一种。
在一些实施例中，本申请提供了一种锂离子电池，其包括上述正极、负极、隔离膜和电解液，所述电解液为本申请前述任一种电解液。
三、电子装置
本申请的电化学装置具有优异的高温循环性能、大倍率放电性能以及降低的内阻，使得本申请的电化学装置适用于各种领域的电子装置。
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用途。在一个实施例中，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。
四、实施例
以下说明根据本申请的锂离子电池的实施例和对比例进行性能评估。
锂离子电池的制备
1)电解液的制备：在含水量<10ppm的氩气气氛手套箱中，将碳酸乙烯酯、碳酸二乙酯、碳酸丙烯酯按照3:4:3的质量比混合均匀，再将充分干燥的锂盐LiPF 6溶解于上述非水溶剂，其中LiPF 6的含量为1mol/L，最后加入一定质量的添加剂，配成实施例和对比例中的电解液。实施例和对比例的添加剂种类和含量如表1、表3和表5所示。
2)正极的制备：将钴酸锂(LiCoO 2)、乙炔黑、聚偏二氟乙烯按重量比96:2:2在适量的N-甲基吡咯烷酮溶剂中充分搅拌混合，使其形成均匀的正极浆料；将此浆料涂覆于正极集流体铝箔上，烘干、冷压，得到正极。
3)负极的制备：将石墨、乙炔黑、丁苯橡胶、羧甲基纤维素钠按照重量比95:2:2:1在适量的去离子水溶剂中充分搅拌混合，使其形成均匀的负极浆料；将此浆料涂覆于负极集流体铜箔上，烘干、冷压，得到负极。
4)隔离膜：以厚度为16μm的聚乙烯多孔聚合物薄膜作为隔离膜。
5)锂离子电池的制备：将正极、隔离膜、负极按顺序叠好，使隔离膜处于正极和负极之间起到隔离的作用，然后卷绕得到裸电池；将裸电池置于外包装箔中，将上述制备好的电解液注入到干燥后的电池中，经过真空封装、静置、化成、整形等工序，即完成锂离子电池的制备。
按照上述制备方法制备实施例以及对比例的电解液及锂离子电池；其中正极活性材料为钴酸锂，负极活性材料为石墨，并对锂离子电池进行高温循环测试、高温存储测试、直流阻抗(DCR)测试、OI值测试、热箱测试和撞击测试。
测试方法
(1)高温循环性能测试
将高电压锂离子电池置于45℃恒温箱中，静置30分钟，使高电压锂离子电池达到恒温；0.7C恒流充电至4.45V，恒压充电至电流为0.05C；07C放电至3.0V，此时为首次循环，记录首次循环的放电容量。按照上述条件使锂离子电池进行循环。计算得出锂离子电池循环500次循环后的容量保持率按照下式进行计算：循环后的容量保持率＝(对应循环的放电容量/首次循环的放电容量)×100％。
(2)高温存储性能测试
将电池在25℃下以0.5C放电至3.0V，在以0.7C充电至4.45V，4.45V下恒压充电至0.05C，用千分尺测试并记录电池的厚度记为H 11，放置到85℃烘箱当中，4.45V恒压16h，16小时结束后用千分尺测试并记录电池的厚度，记为H 12。
厚度膨胀率＝(H 12-H 11)/H 11*100％。
(3)高电压锂离子电池直流阻抗DCR(0℃)测试
按照如下步骤对锂离子电池进行测试：
1)在0℃高低温箱中静置4h；
2)0.1C恒流充电至4.45V，恒压充电至0.05C，静置10min；
3)0.1C恒流放电至3.4V，静置5min(得到实际容量)；
4)静置5min，0.1C恒流充电至4.45V，恒压充电至0.05C(用第3步得到的实际容量计算)；
5)静置10min；
6)0.1C恒流放电8h(用第3步得到的实际容量计算)，记录此时的电压为V 1；
7)1C恒流放电1s(容量以电池标注容量计算)，记录此时的电压为V 2；
8)计算电池20％SOC状态对应直流阻抗，20％SOC直流阻抗＝(V 1-V 2)/1C。
(4)OI值测试
采用布鲁克X射线衍射(XRD)仪测试负极活性材料的OI值，按照X射线衍射仪分析法通则、人造石墨的点阵参数测试方法JIS K0131-1996、JB/T 4220-2011测试其XRD。004峰的峰面积与110峰的峰面积的比值C004/C110记为OI值，其中峰面积由峰强与半峰宽积分得到。
(5)热箱性能测试
在室温下，锂离子电池以0.7C恒流充电至电压4.45V，室温下静置60min，记录测试前锂离子电池的OCV(开路电压)和IMP(阻抗)、检查外观并拍照，以3℃/min±2℃/min的速率升至135℃±2℃，并保持60min。每组测试5个电池，以样品不着火，不爆炸为通过，记录通过测试电池个数。
(6)撞击测试
在测试前需充电，充电流程如下：室温下，锂离子电池以0.7C恒流充电至电压4.45V，室温下静置60min，记录测试前OCV和IMP，检查外观并拍照，将直径为φ15.8mm，长度至少6cm圆棒垂直于试样，用9Kg的重锤，距离圆棒与试样交叉处61cm，垂直自由状态落下。结束测试后，记录OCV和IMP，检查外观并拍照。样品不着火，不爆炸为通过。
测试结果
下面根据实施例和对比例的测试结果详细讨论式I化合物、LiPO 2F 2、腈化合物、磷酸酯化合物、负极活性材料的OI值以及基于单位正极活性材料的式I化合物含量对锂离子电池性能的影响。在本申请中，实施例1至实施例38以及对比例1和2的负极活性材料的OI值均为15.9。
表1示出了实施例1至18和对比例1和2中电解液的参数。表2示出了实施例1至18以及对比例1和2的锂离子电池的电性能测试结果。
表1
Figure PCTCN2020093220-appb-000023
表2
Figure PCTCN2020093220-appb-000024
Figure PCTCN2020093220-appb-000025
通过对比实施例1至7和对比例1可以看出，在电解液中加入式I化合物对锂离子电池的高温循环性能、高温存储性能和阻抗均有较好的改善效果，这是由于式I化合物在正极表面形成致密稳定的界面膜，阻止了溶剂在正极表面的副反应，稳定正极界面，且形成的界面膜阻抗小。
通过对比实施例8至16和对比例1可以看出，在电解液中加入式I化合物和LiPO 2F 2，利用两者的协同作用，可以进一步改善锂离子电池的高温循环性能并降低阻抗。
由实施例8至18与对比例2可以得知，当a+b≥4.5时，因添加剂加入量加多，会影响锂离子的传输；当a/b≤1/10时，因添加量较少改善的效果不明显。
表3示出了实施例19至31中电解液的参数。表4示出了实施例19至31的锂离子电池的电性能测试结果。
表3
Figure PCTCN2020093220-appb-000026
Figure PCTCN2020093220-appb-000027
表4
Figure PCTCN2020093220-appb-000028
通过实施例20至22可知，在电解液中加入式I化合物腈化合物可以进一步改善锂离子电池的高温循环性能和高温存储性能。
通过实施例23至32可知，在电解液中加入式I化合物、腈化合和LiPO 2F 2可进一步提升电池性能。
通过对比实施例33和实施例34可知，当腈化合物的含量超过10wt％时，再增加腈化合物的含量时，高温循环性能的改善效果会降低，这是因为高含量的腈化合物增加了电解液的粘度，恶化了锂离子电池的动力学。
表5示出了实施例35至44中电解液的参数。表6示出了实施例35至44的锂离子电池的电性能测试结果。
表5
Figure PCTCN2020093220-appb-000029
表6
Figure PCTCN2020093220-appb-000030
从实施例35至44可知，在电解液中加入式I化合物和磷酸酯化合物可以明显降低电解液的可燃性，显著提升锂离子电池的热箱通过率和撞击通过率。这主要归因于式I化合物和磷酸酯化合物共同作用，增强了自由基对H/O等离子的捕捉，降低了电解液的可燃性。同时高温存储测试表明，式I化合物和磷酸酯化合物对于锂离子电池的胀气变形有明显的抑制作用，这主要是由于该电解液对高温、高电压状态下正极中的活性氧的固定，减少了活性氧与电解液副反应的发生，进而降低了二氧化碳等气体的产生，起到了改善高温存储性能的目的。
通过对比实施例39至43与实施例44可知，当电解液中磷酸酯化合物的含量超过 10wt％时，随着磷酸酯化合物(例如，式V-2)含量的增大，锂离子电池的高温循环性能恶化越严重。这主要是因为磷酸酯化合物的粘度较大，过大含量的磷酸酯化合物会恶化电解液的电导率；同时由于其较高的还原电位，对负极也存在较严重的恶化，造成析锂等风险，因此会严重影响锂离子电池的动力学，使其应用受到限制。
表7示出了实施例45至51的正负极参数以及锂离子电池的电性能测试结果。实施例45至51的电解液与实施例22相同，基于每克正极活性材料的式I化合物量是通过调整正极活性材料重量得到。
表7
Figure PCTCN2020093220-appb-000031
通过实施例45至48与实施例22相比可知，负极活性材料的OI值在8-15范围内能够有效改善锂离子电池的高温循环性能，并且在此范围内，OI值越小，其改善效果越明显。这是由于OI值越小，负极在受压过程中，受压面越多，受力的方向增多，受力更加均匀。在锂离子电池循环过程中，由于受压面增多，锂离子嵌入或脱出时石墨层间所产生的应力能够得到抑制或抵消，从而大大改善高温循环。
通过实施例49至51与实施例22相比可知，在一定范围内，当对应于单位质量正极活性材料的式I化合物含量减少时，对锂离子电池的高温存储与循环性能的改善效果会减弱，这是因为式I化合物含量相对降低时，对正极活性材料的保护效果不明显，从而导致高温循环和高温存储性能的改善效果减弱。
整个说明书中对“一些实施例”、“部分实施例”、“一个实施例”、“另一举例”、“举例”、“具体举例”或“部分举例”的引用，其所代表的意思是在本申请中的至少一个实施例或举例包含了该实施例或举例中所描述的特定特征、结构、材料或特性。因 此，在整个说明书中的各处所出现的描述，例如：“在一些实施例中”、“在实施例中”、“在一个实施例中”、“在另一个举例中”，“在一个举例中”、“在特定举例中”或“举例“，其不必然是引用本申请中的相同的实施例或示例。此外，本文中的特定特征、结构、材料或特性可以以任何合适的方式在一个或多个实施例或举例中结合。
尽管已经演示和描述了说明性实施例，本领域技术人员应该理解上述实施例不能被解释为对本申请的限制，并且可以在不脱离本申请的精神、原理及范围的情况下对实施例进行改变，替代和修改。

Claims (13)

  1. 一种电解液，其包含式I化合物
    Figure PCTCN2020093220-appb-100001
    其中R 1选自卤素原子、取代或未取代的C 1至C 10烷基、取代或未取代的C 2至C 10直链或支链烯基、取代或未取代的C 2至C 10直链或支链炔基，其中经取代时，取代基为卤素原子；
    其中R 2选自取代或未取代的C 1至C 6亚烷基或取代或未取代的C 2至C 6亚烯基，其中经取代时，取代基为卤素原子；
    其中X选自-S(＝O)O、-O-S(＝O)O、-S(＝O) 2O、-O-S(＝O) 2O、-C(＝O)O、-O-C(＝O)O、-PO 3H、-OPO 3H或-BO 2H；
    其中A选自亚甲基或氧原子。
  2. 根据权利要求1所述的电解液，所述式I化合物包含：
    Figure PCTCN2020093220-appb-100002
    Figure PCTCN2020093220-appb-100003
    中的至少一种；
    基于所述电解液的重量，所述式I化合物的含量为0.05wt％-3.5wt％。
  3. 根据权利要求1所述的电解液，其中所述电解液还包括二氟磷酸锂，基于所述电解液的重量，所述二氟磷酸锂的含量小于1wt％。
  4. 根据权利要求3所述的电解液，其中基于所述电解液的重量，所述式I化合物的含量a％与所述二氟磷酸锂的含量b％满足a+b<4.5且a/b>1:10。
  5. 根据权利要求1所述的电解液，其还包含腈化合物，所述腈化合物包含式II、式III或式IV所示的化合物中的至少一种：
    Figure PCTCN2020093220-appb-100004
    其中，R 21选自取代或未取代的C 1至C 10亚烷基、取代或未取代的C 2至C 10亚烯基或含有至少一个醚键的C 2至C 6直链或支链的亚烷基或亚烯基，其中经取代时，取代基为卤素原子、硝基、氰基、羧基或硫酸基中的至少一种；
    其中R 31、R 32、R 33各自独立地选自单键、取代或未取代的C 1至C 10亚烷基或含有至少一个醚键的C 2至C 6直链或支链的亚烷基或亚烯基，其中经取代时，取代基为卤素原子、硝基、氰基、羧基或硫酸基中的至少一种；
    其中R 41选自取代或未取代的C 1至C 10亚烷基、取代或未取代的C 2至C 10亚烯基、取代或未取代的C 6至C 10亚芳基、取代或未取代的C 3至C 6亚环烷基或取代或未取代的C 6至C 10杂环基团，其中经取代时，取代基为卤素原子、硝基、氰基、羧基或硫酸基中的至少一种，其中所述杂环基团包含O、S、N或P中的至少一种；
    其中基于所述电解液的重量，所述腈化合物的含量为0.5wt％-10wt％。
  6. 根据权利要求5所述的电解液，其中腈化合物包含
    Figure PCTCN2020093220-appb-100005
    Figure PCTCN2020093220-appb-100006
    中的至少一种。
  7. 根据权利要求1所述的电解液，其还包含磷酸酯化合物，所述磷酸酯化合物包含式V化合物
    Figure PCTCN2020093220-appb-100007
    其中R 51、R 52、R 53各自独立地选自氢、取代或未取代的C 1至C 5烷基、取代或未取代的C 2至C 10烯基、取代或未取代的C 6至C 10芳基或取代或未取代的C 1至C 6的杂环基团，其中经取代时，取代基为卤素原子、硝基、氰基、羧基、硫酸基、磷酸酯基或硅烷基中的至少一种；
    其中基于所述电解液的重量，所述磷酸酯化合物的含量为0.1wt％-10wt％。
  8. 根据权利要求7所述的电解液，其中磷酸酯化合物包含
    Figure PCTCN2020093220-appb-100008
    Figure PCTCN2020093220-appb-100009
    中的至少一种。
  9. 根据权利要求1所述的电解液，其中所述电解液包含非水有机溶剂，其中所述非水有机溶剂包括碳酸乙烯酯、碳酸丙烯酯、碳酸二甲酯、碳酸二乙酯、碳酸甲乙酯、γ-丁内酯、乙酸甲酯、乙酸乙酯、乙酸丙酯、乙酸丁酯、丙酸甲酯、丙酸乙酯、丙酸丙酯、丙酸丁酯、丁酸甲酯、丁酸乙酯或丁酸丙酯中的至少一种。
  10. 一种电化学装置，其包括正极、负极、隔离膜和如权利要求1-9中任一权利要求所述的电解液。
  11. 根据权利要求10所述的电化学装置，其中所述负极包括负极活性材料，所述负极活性材料的OI值为8-15。
  12. 根据权利要求9所述的电化学装置，其中所述正极包括正极活性材料，基于每克所述正极活性材料，电解液中的式I化合物的含量为0.025g-0.35g。
  13. 一种电子装置，其包括如权利要求10-12中任一权利要求所述的电化学装置。
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