WO2024168804A1 - 电解液和电化学装置 - Google Patents

电解液和电化学装置 Download PDF

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Publication number
WO2024168804A1
WO2024168804A1 PCT/CN2023/076752 CN2023076752W WO2024168804A1 WO 2024168804 A1 WO2024168804 A1 WO 2024168804A1 CN 2023076752 W CN2023076752 W CN 2023076752W WO 2024168804 A1 WO2024168804 A1 WO 2024168804A1
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Prior art keywords
compound
electrolyte
formula
substituted
content
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English (en)
French (fr)
Inventor
彭谢学
简俊华
刘俊飞
唐超
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Ningde Amperex Technology Ltd
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Ningde Amperex Technology Ltd
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Priority to CN202380011791.5A priority Critical patent/CN117355973A/zh
Priority to PCT/CN2023/076752 priority patent/WO2024168804A1/zh
Publication of WO2024168804A1 publication Critical patent/WO2024168804A1/zh
Anticipated expiration legal-status Critical
Priority to US19/302,393 priority patent/US20250379253A1/en
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
    • H01M10/0564—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of organic materials only
    • H01M10/0566—Liquid materials
    • H01M10/0567—Liquid materials characterised by the additives
    • 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
    • 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
    • H01M10/0568—Liquid materials characterised by the solutes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M2300/00—Electrolytes
    • H01M2300/0017—Non-aqueous electrolytes
    • H01M2300/0025—Organic electrolyte
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Definitions

  • the present application relates to the field of energy storage, and in particular to an electrolyte and an electrochemical device.
  • electrochemical devices e.g., lithium-ion batteries
  • users have put forward higher and higher requirements for the performance of electrochemical devices, especially focusing on the long cycle life and self-discharge of electrochemical devices.
  • the life of an electrochemical device is affected by the impedance growth during its cycle process, and the voltage drop of an electrochemical device during high-temperature storage can reflect its self-discharge.
  • the factors that affect the impedance growth of electrochemical devices during cycling and the voltage drop during high-temperature storage include the stability between the active material interface and the electrolyte interface. When the stability between the interfaces is poor, the electrolyte will continue to decompose. Improving the stability between the active material interface and the electrolyte interface to inhibit the decomposition of the electrolyte has become one of the problems that need to be solved urgently.
  • the present application attempts to solve at least one problem existing in the related art to at least some extent by providing an electrolyte and an electrochemical device.
  • the present application provides an electrolyte, including a compound of formula IA, a compound of formula IB and a compound of formula IC:
  • n is an integer selected from 1 to 8;
  • R 11 , R 12 , R 13 and R 14 are each independently selected from hydrogen, halogen or substituted or unsubstituted C 1 -C 5 alkyl, and at least one of R 11 , R 12 , R 13 and R 14 is substituted or unsubstituted C 1 -C 5 alkyl;
  • R 15 is selected from C 2 -C 4 alkylene, C 2 -C 4 alkenylene,
  • R 17 , R 18 and R 19 are each independently selected from a single bond, a C 1 -C 5 alkylene group or a C 1 -C 5 alkyleneoxy group;
  • each substituent is independently halogen
  • the content of the compound of formula I-A is X%, where X is in the range of 0.12 to 5.0;
  • the content of the compound of formula I-B is Y%, where Y is in the range of 0.12 to 5.0;
  • the content of the compound of formula I-C is Z%, where Z is in the range of 0.12 to 3.0.
  • the compound of formula I-A, the compound of formula I-B and the compound of formula I-C are all polynitrile compounds.
  • the presence of multiple cyano groups can stabilize the positive electrode active material (for example, the transition metal in the positive electrode active material).
  • the compound of formula I-A has a side chain, which increases the steric hindrance and enhances the protection of the positive electrode interface, but its viscosity is relatively large.
  • the compound of formula I-B has a relatively small viscosity.
  • the compound of formula I-C has strong stability to the positive electrode active material.
  • the electrolyte contains a specific content of the compound of formula I-A, the compound of formula I-B and the compound of formula I-C, which can effectively improve the cycle performance and high temperature storage performance of the electrochemical device containing the electrolyte.
  • X is in the range of 0.5 to 4.2; Y is in the range of 0.5 to 4.2; and Z is in the range of 0.5 to 3.0.
  • Z/X is in the range of 0.1 to 3.
  • Z/X is in the range of 0.6 to 2.5.
  • the compound of formula IA includes at least one of the following compounds:
  • the compound of formula IB includes at least one of the following compounds:
  • the compound of formula IC includes at least one of the following compounds:
  • Y/X is in the range of 0.12 to 5.
  • the electrolyte further includes a compound containing a sulfur-oxygen double bond, and the content of the compound containing a sulfur-oxygen double bond is 0.01% to 10% based on the mass of the electrolyte.
  • the compound containing a sulfur-oxygen double bond includes a compound having Formula II:
  • R 21 and R 22 are each independently selected from a substituted or unsubstituted C 1 -C 5 alkyl group, a substituted or unsubstituted C 2 -C 10 alkenyl group, a substituted or unsubstituted C 2 -C 10 alkynyl group, a substituted or unsubstituted C 3 -C 10 alicyclic group, a substituted or unsubstituted C 6 -C 10 aryl group, or a substituted or unsubstituted C 1 -C 5 heteroatom functional group, wherein the heteroatom in the heteroatom functional group is selected from at least one of O and S;
  • R 21 and R 22 are optionally linked together to form a ring
  • the substituents are each independently selected from halogen.
  • the compound containing a sulfur-oxygen double bond includes at least one of the following compounds:
  • the stability of the positive electrode interface and the negative electrode interface can be effectively improved without significantly affecting the viscosity of the electrolyte and the impedance of the positive electrode interface and the negative electrode interface, which can further improve the cycle performance and high-temperature storage performance of the electrochemical device.
  • the electrolyte further comprises a compound of formula III:
  • R 31 is selected from substituted or unsubstituted C 1 -C 6 alkylene or substituted or unsubstituted C 2 -C 6 alkenylene;
  • the substituents are each independently selected from halogen, C 1 -C 6 alkyl or C 2 -C 6 alkenyl;
  • the content of the compound of formula III is 0.01% to 15%.
  • the compound of formula III includes at least one of the following compounds:
  • the negative electrode interface can be fully protected, and the cycle performance and high-temperature storage performance of the electrochemical device can be further improved.
  • the electrolyte further includes compound IV, and the compound IV includes at least one of the following compounds:
  • the content of the compound IV is 0.01% to 2%.
  • the electrolyte further includes a boron-containing lithium salt, and based on the mass of the electrolyte, the content of the boron-containing lithium salt is 0.01% to 1%.
  • the boron-containing lithium salt includes at least one of lithium tetrafluoroborate, lithium dioxalatoborate or lithium difluorooxalatoborate.
  • the content of the boron-containing lithium salt is M%, and M/X is not greater than 1.
  • the cycle impedance growth of the electrochemical device can be further reduced, and the cycle performance of the electrochemical device can be further significantly improved.
  • the present application provides an electrochemical device, which includes a positive electrode, a negative electrode and the electrolyte according to the present application.
  • the present application provides an electronic device, which includes the electrochemical device according to the present application.
  • the present application provides an electrolyte, an electrochemical device and an electronic device.
  • the electrolyte contains specific contents of the compound of formula I-A, the compound of formula I-B and the compound of formula I-C at the same time, the electrolyte has an appropriate viscosity and can stabilize the positive electrode active material, protect the positive electrode interface, and inhibit the decomposition of the electrolyte, thereby significantly reducing the cycle impedance growth and high-temperature storage voltage drop of the electrochemical device, thereby significantly improving the cycle performance and high-temperature storage performance of the electrochemical device, and at the same time, an electrolyte with a lower viscosity can be obtained, thereby improving the kinetic performance of the electrochemical device.
  • a list of items connected by the term "at least one of” can mean any combination of the listed items. For example, if items A and B are listed, 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, 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 can include a single element or multiple elements.
  • Item B can include a single element or multiple elements.
  • Item C can include a single element or multiple elements.
  • alkyl refers to a straight chain 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. When specifying an alkyl with a specific carbon number, it is expected to cover all geometric isomers with that carbon number; therefore, for example, “butyl” means including n-butyl, sec-butyl, isobutyl, tert-butyl and cyclobutyl; “propyl” includes n-propyl, isopropyl and cyclopropyl.
  • Alkyl examples 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, etc.
  • alkenyl refers to a monovalent unsaturated hydrocarbon group which may be straight or branched and has at least one, and typically 1, 2 or 3, carbon-carbon double bonds. Unless otherwise defined, the alkenyl group typically contains 2 to 20 carbon atoms and includes, for example, -C2-4 alkenyl, -C2-6 alkenyl and -C2-10 alkenyl. Representative alkenyl groups include, for example, vinyl, n-propenyl, isopropenyl, n-but-2-enyl, but-3-enyl, n-hex-3-enyl, and the like.
  • alkynyl refers to a monovalent unsaturated hydrocarbon group which may be straight or branched and has at least one and typically 1, 2 or 3 carbon-carbon triple bonds. Unless otherwise defined, the alkynyl group typically contains 2 to 20 carbon atoms and includes, for example, -C 2-4 alkynyl, -C 3-6 alkynyl and -C 3-10 alkynyl. Representative alkynyl groups include, for example, ethynyl, prop-2-ynyl (n-propynyl), n-but-2-ynyl, n-hex-3-ynyl, and the like.
  • alkylene encompasses straight and branched chain alkylene.
  • the alkylene may be C 1 -C 50 alkylene, C 1 -C 40 alkylene, C 1 -C 30 alkylene, C 1 -C 20 alkylene, C 1 -C 10 alkylene, C 1 -C 6 alkylene, C 2 -C 6 alkylene, C 2 -C 5 alkylene.
  • alkenylene encompasses straight-chain and branched alkenylene.
  • the alkenylene may be C2 - C50 alkenylene, C2- C40 alkenylene, C2 - C30 alkenylene , C2 - C20 alkenylene, C2 - C10 alkenylene, C1 - C6 alkenylene, C2- C6 alkenylene .
  • aryl means a monovalent aromatic hydrocarbon having a single ring (e.g., phenyl) or a fused ring.
  • Fused ring systems include those that are fully unsaturated (e.g., naphthalene) as well as those that are partially unsaturated (e.g., 1,2,3,4-tetrahydronaphthalene).
  • the aryl group typically contains 6 to 26 carbon ring atoms and includes, for example, -C 6-10 aryl.
  • Representative aryl groups include, for example, phenyl, methylphenyl, propylphenyl, isopropylphenyl, benzyl, and naphth-1-yl, naphth-2-yl, and the like.
  • halogen may be F, Cl, Br or I.
  • heteroatom encompasses O, S, P, N, B or isosteres thereof.
  • heteroatom functional group refers to a functional group containing a heteroatom, wherein the heteroatom contains at least one of the elements O, S, P, N or B.
  • heteroatom functional groups include, but are not limited to, C0- C5 sulfonate groups, C0 - C5 sulfate groups, C0 - C5 ether groups, C0 - C5 sulfinate groups, C0 - C5 sulfite groups, C0 - C5 phosphate groups, C0-C5 borate groups , and the like.
  • alicyclic group refers to a saturated, partially unsaturated or unsaturated mono-, bi-, tri- or polycyclic group having about 3 to 15 carbons, or 3 to 12 carbons, or 3 to 8 carbons, or 3 to 6 carbons, or 5 or 6 carbons.
  • Examples of alicyclic groups include, but are not limited to, cyclopropyl, cyclobutyl, cyclobutenyl, cyclopentyl, cyclopentenyl, cyclohexyl, cyclohexenyl, cycloheptyl, cyclooctyl, and the like.
  • the main method to improve the energy density of electrochemical devices includes increasing the charging voltage of the electrochemical devices.
  • the higher charging voltage will accelerate the oxidative decomposition of the electrolyte by the positive electrode active material (e.g., the high-valent transition metal therein), and will also lead to oxygen release, further accelerating the decomposition of the electrolyte, thereby increasing the gas production of the electrochemical device, thereby affecting the cycle performance and high-temperature storage performance of the electrochemical device.
  • an electrolyte comprising a compound of formula IA, a compound of formula IB and a compound of formula IC:
  • n is an integer selected from 1 to 8;
  • R 11 , R 12 , R 13 and R 14 are each independently selected from hydrogen, halogen or substituted or unsubstituted C 1 -C 5 alkyl, and at least one of R 11 , R 12 , R 13 and R 14 is substituted or unsubstituted C 1 -C 5 alkyl;
  • R 15 is selected from C 2 -C 4 alkylene, C 2 -C 4 alkenylene,
  • R 17 , R 18 and R 19 are each independently selected from a single bond, a C 1 -C 5 alkylene group or a C 1 -C 5 alkyleneoxy group;
  • each substituent is independently halogen
  • the content of the compound of formula I-A is X%, where X is in the range of 0.12 to 5.0;
  • the content of the compound of formula I-B is Y%, where Y is in the range of 0.12 to 5.0;
  • the content of the compound of formula I-C is Z%, wherein Z is in the range of 0.12 to 3.0.
  • the compound of formula IA, the compound of formula IB and the compound of formula IC are all polynitrile compounds.
  • the presence of multiple cyano groups can stabilize the positive electrode active material (for example, the transition metal in the positive electrode active material).
  • the compound of formula IA has a side chain, which will increase the steric hindrance and enhance the protection of the positive electrode interface, but its viscosity is relatively large.
  • the compound of formula IB has a relatively small viscosity.
  • the compound of formula IC has strong stability to the positive electrode active material. When the content of the compound of formula IA, the compound of formula IB and the compound of formula IC in the electrolyte is too low, it is difficult to play an effective role.
  • the electrolyte contains a specific amount of the compound of formula IA, the compound of formula IB and the compound of formula IC at the same time, the electrolyte has an appropriate viscosity and can stabilize the positive electrode active material, protect the positive electrode interface, and inhibit the decomposition of the electrolyte, thereby significantly reducing the cycle impedance growth and
  • the high-temperature storage voltage drop significantly improves the cycle performance and high-temperature storage performance of the electrochemical device, while a lower viscosity electrolyte can be obtained, which improves the kinetic performance of the electrochemical device.
  • X is in the range of 0.2 to 4.5. In some embodiments, X is in the range of 0.5 to 4.2. In some embodiments, X is in the range of 1.0 to 4.0. In some embodiments, X is in the range of 1.5 to 3.5. In some embodiments, X is in the range of 2.0 to 3.0. In some embodiments, X is 0.12, 0.2, 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, 5.0, or in a range consisting of any two of the above values.
  • Y is in the range of 0.2 to 4.5. In some embodiments, Y is in the range of 0.5 to 4.2. In some embodiments, Y is in the range of 1.0 to 4.0. In some embodiments, Y is in the range of 1.5 to 3.5. In some embodiments, Y is in the range of 2.0 to 3.0. In some embodiments, Y is 0.12, 0.2, 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, 5.0, or in the range consisting of any two of the above values.
  • Z is in the range of 0.2 to 2.5. In some embodiments, Z is in the range of 0.5 to 2.0. In some embodiments, Z is in the range of 1.0 to 1.5. In some embodiments, Z is 0.12, 0.2, 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, or in the range consisting of any two of the above values.
  • the compound of formula IA comprises at least one of the following compounds:
  • the compound of formula IB comprises at least one of the following compounds:
  • the compound of formula IC includes at least one of the following compounds:
  • Z/X is in the range of 0.1 to 3. In some embodiments, Z/X is in the range of 0.3 to 2.8. In some embodiments, Z/X is in the range of 0.6 to 2.5. In some embodiments, Z/X is in the range of 1 to 2. In some embodiments, Z/X is 0.1, 0.5, 0.6, 1, 1.5, 2, 2.5, 3, or in the range consisting of any two of the above values. When Z/X is in the above range, the cycle performance and high temperature storage performance of the electrochemical device can be further improved.
  • Y/X is in the range of 0.12 to 5. In some embodiments, Y/X is in the range of 0.5 to 4.5. In some embodiments, Y/X is in the range of 1 to 4. In some embodiments, Y/X is in the range of 1.5 to 3.5. In some embodiments, Y/X is in the range of 2 to 3. In some embodiments, Y/X is 0.12, 0.2, 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, or in the range consisting of any two of the above values. When Y/X is in the above range, the cycle performance and high temperature storage performance of the electrochemical device can be further improved.
  • the electrolyte further comprises a compound containing a sulfur-oxygen double bond
  • the content of the compound containing a sulfur-oxygen double bond is 0.01% to 10% based on the mass of the electrolyte.
  • the content of the compound containing a sulfur-oxygen double bond is 0.05% to 8% based on the mass of the electrolyte.
  • the content of the compound containing a sulfur-oxygen double bond is 0.1% to 6% based on the mass of the electrolyte.
  • the content of the compound containing a sulfur-oxygen double bond is 0.5% to 5% based on the mass of the electrolyte.
  • the content of the compound containing a sulfur-oxygen double bond is 1% to 4% based on the mass of the electrolyte. In some embodiments, the content of the compound containing a sulfur-oxygen double bond is 2% to 3% based on the mass of the electrolyte. In some embodiments, based on the mass of the electrolyte, the content of the compound containing sulfur-oxygen double bonds is 0.01%, 0.05%, 0.1%, 0.5%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10% or within the range of any two of the above values.
  • the compound containing a sulfur-oxygen double bond includes a compound having Formula II:
  • R 21 and R 22 are each independently selected from a substituted or unsubstituted C 1 -C 5 alkyl group, a substituted or unsubstituted C 2 -C 10 alkenyl group, a substituted or unsubstituted C 2 -C 10 alkynyl group, a substituted or unsubstituted C 3 -C 10 alicyclic group, a substituted or unsubstituted C 6 -C 10 aryl group, or a substituted or unsubstituted C 1 -C 5 heteroatom functional group, wherein the heteroatom in the heteroatom functional group is selected from at least one of O and S;
  • R 21 and R 22 are optionally linked together to form a ring
  • the substituents are each independently selected from halogen.
  • R 21 and R 22 are optionally linked together to form a 5-membered ring or a 6-membered ring. In some embodiments, R 21 and R 22 are optionally linked together to form a 5-membered cyclic sulfone, a 6-membered cyclic sulfone, a 5-membered sulfate, a 6-membered sulfate, a 5-membered cyclic sulfonate, a 6-membered sulfonate, a 5-membered cyclic sulfonic acid anhydride, or a 6-membered cyclic sulfonic acid anhydride, etc.
  • the compound containing a sulfur-oxygen double bond comprises at least one of the following compounds:
  • sulfur-oxygen double bond compounds have strong antioxidant capacity and can improve the stability of the positive electrode interface.
  • sulfur-oxygen double bond compounds can be reduced on the negative electrode surface to form a protective film, inhibiting the decomposition of the electrolyte and further enhancing the stability of the negative electrode interface.
  • the electrolyte further includes a certain amount of sulfur-oxygen double bond compounds, it can not only effectively improve the stability of the positive electrode interface and the negative electrode interface, but also will not significantly affect the viscosity of the electrolyte and the impedance of the positive electrode interface and the negative electrode interface, thereby further improving the cycle performance and high temperature storage performance of the electrochemical device.
  • the electrolyte further comprises a compound of formula III:
  • R 31 is selected from substituted or unsubstituted C 1 -C 6 alkylene or substituted or unsubstituted C 2 -C 6 alkenylene;
  • the substituents are each independently selected from halogen, C 1 -C 6 alkyl or C 2 -C 6 alkenyl;
  • the content of the compound of formula III is 0.01% to 15%.
  • the content of the compound of formula III is 0.05% to 12% based on the mass of the electrolyte. In some embodiments, the content of the compound of formula III is 0.1% to 10% based on the mass of the electrolyte. In some embodiments, the content of the compound of formula III is 0.5% to 8% based on the mass of the electrolyte. In some embodiments, the content of the compound of formula III is 1% to 5% based on the mass of the electrolyte. In some embodiments, the content of the compound of formula III is 2% to 4% based on the mass of the electrolyte.
  • the content of the compound of formula III is 0.01%, 0.05%, 0.1%, 0.5%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15% or in the range of any two of the above values based on the mass of the electrolyte.
  • the compound of formula III comprises at least one of the following compounds:
  • the compound of formula III can assist in enhancing the film formation stability of the negative electrode solid interface film (SEI), increase the flexibility of the SEI film, enhance the protection of the negative electrode active material, and reduce the probability of interface contact between the negative electrode active material and the electrolyte, thereby reducing the impedance of the electrochemical device during the cycle.
  • SEI negative electrode solid interface film
  • the electrolyte further includes a certain amount of the compound of formula III, the negative electrode interface can be fully protected, and the cycle performance and high temperature storage performance of the electrochemical device can be further improved.
  • the electrolyte further comprises compound IV, wherein compound IV comprises at least one of the following compounds:
  • Compound IV contains at least 3 cyano groups (-CN), which have a stronger protective effect on the positive electrode interface.
  • Compound IV can work together with the compound of formula I-A, the compound of formula I-B and the compound of formula I-C in the electrolyte to further inhibit the decomposition of the electrolyte, thereby further reducing the cycle impedance growth and high-temperature storage thickness expansion rate of the electrochemical device, and further significantly improving the cycle performance and high-temperature storage performance of the electrochemical device.
  • the content of compound IV is 0.01% to 2% based on the mass of the electrolyte. In some embodiments, the content of compound IV is 0.05% to 1.5% based on the mass of the electrolyte. In some embodiments, the content of compound IV is 0.1% to 1% based on the mass of the electrolyte. In some embodiments, the content of compound IV is 0.2% to 0.5% based on the mass of the electrolyte. In some embodiments, the content of compound IV is 0.01%, 0.05%, 0.1%, 0.5%, 1%, 1.5%, 2% or in the range of any two of the above values based on the mass of the electrolyte. When the content of compound IV in the electrolyte is within the above range, the cycle performance and high temperature storage performance of the electrochemical device can be further improved.
  • the electrolyte further comprises a boron-containing lithium salt, and the content of the boron-containing lithium salt is 0.01% to 1% based on the mass of the electrolyte. In some embodiments, the content of the boron-containing lithium salt is 0.05% to 0.8% based on the mass of the electrolyte. In some embodiments, the content of the boron-containing lithium salt is 0.1% to 0.6% based on the mass of the electrolyte. In some embodiments, the content of the boron-containing lithium salt is 0.2% to 0.5% based on the mass of the electrolyte.
  • the content of the boron-containing lithium salt is 0.01%, 0.05%, 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1% or in the range of any two of the above values based on the mass of the electrolyte.
  • the boron-containing lithium salt includes lithium tetrafluoroborate, lithium dioxalate borate or lithium difluorooxalate. At least one of lithium borates.
  • the boron-containing lithium salt can form a film on the positive electrode, and it can work together with the compound of formula I-A, the compound of formula I-B and the compound of formula I-C to stabilize the positive electrode interface.
  • the electrolyte further contains a certain amount of boron-containing lithium salt, the cycle impedance growth of the electrochemical device can be further reduced, and the cycle performance of the electrochemical device can be further significantly improved.
  • the content of the boron-containing lithium salt is M%, and M/X is not greater than 1.
  • M/X is 0.01 to 0.8.
  • M/X is 0.05 to 0.6.
  • M/X is 0.1 to 0.5.
  • M/X is 0.2 to 0.4.
  • M/X is 0.01, 0.02, 0.05, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1 or in the range of any two of the above values.
  • the electrolyte may also include other non-aqueous organic solvents and electrolyte salts.
  • the non-aqueous organic solvent may include at least one of carbonates, carboxylates, ethers or other aprotic solvents.
  • Examples of carbonate solvents include dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, dipropyl carbonate, ethylene carbonate, propylene carbonate, butylene carbonate, di(2,2,2-trifluoroethyl) carbonate, etc.
  • carboxylate solvents include methyl acetate, ethyl acetate, n-propyl acetate, n-butyl acetate, methyl propionate, ethyl propionate, propyl propionate, butyl propionate, methyl butyrate, ethyl butyrate, propyl butyrate, butyl butyrate, ⁇ -butyrolactone, 2,2-difluoroethyl acetate, valerolactone, butyrolactone, ethyl 2-fluoroacetate, ethyl 2,2-difluoroacetate, ethyl trifluoroacetate, ethyl 2,2,3,3,3-pentafluoropropionate, 2,2,3,3, 4,4,4,4-heptafluorobutyric acid methyl ester, 4,4,4-trifluoro-3-(trifluoromethyl)butyric acid methyl ester, 2,2,3,3,4,4,5,5,
  • ether solvents include ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, dibutyl ether, tetrahydrofuran, 2-methyltetrahydrofuran, bis(2,2,2-trifluoroethyl) ether, etc.
  • the electrolyte salt includes at least one of an organic lithium salt or an inorganic lithium salt. In some embodiments, the electrolyte salt includes at least one of lithium hexafluorophosphate LiPF 6 , lithium bistrifluoromethanesulfonyl imide LiN(CF 3 SO 2 ) 2 (abbreviated as LiTFSI), lithium bis(fluorosulfonyl)imide Li(N(SO 2 F) 2 ) (abbreviated as LiFSI) or lithium hexafluorocesium oxide (LiCsF 6 ), lithium perchlorate LiClO 4 , and lithium trifluoromethanesulfonate LiCF 3 SO 3 .
  • LiTFSI lithium bistrifluoromethanesulfonyl imide LiN(CF 3 SO 2 ) 2
  • LiFSI lithium bis(fluorosulfonyl)imide Li(N(SO 2 F) 2 )
  • LiFSI lithium hexafluoro
  • the electrolyte salt has a content of 10% to 15% by weight of the electrolyte. In some embodiments, the electrolyte salt has a content of 12% to 15% by weight of the electrolyte. When the content of the electrolyte salt is within the above range, the electrolyte has suitable ion conductivity and viscosity, so that the electrochemical device has good rate performance and cycle performance.
  • the present application also provides an electrochemical device.
  • the electrochemical device includes an electrode assembly and an electrolyte, wherein the electrode assembly includes a positive electrode, a negative electrode, and a separator disposed between the positive electrode and the negative electrode.
  • the electrolyte is the electrolyte described in the present application.
  • the negative electrode may include a negative electrode current collector and a negative electrode active material layer disposed on the negative electrode current collector.
  • the negative electrode active material layer may be disposed on one side or both sides of the negative electrode current collector.
  • the negative electrode current collector may be at least one of copper foil, aluminum foil, nickel foil, or a carbon-based current collector.
  • the thickness of the negative electrode current collector may be 1 ⁇ m to 200 ⁇ m.
  • the negative electrode active material layer may be coated only on a partial area of the negative electrode current collector.
  • the thickness of the negative electrode active material layer may be 10 ⁇ m to 500 ⁇ m. It should be understood that these are exemplary only and other suitable thicknesses may be used.
  • the negative electrode active material layer includes a negative electrode active material.
  • the negative electrode active material in the negative electrode active material layer includes at least one of lithium metal, natural graphite, artificial graphite, or a silicon-based material.
  • the silicon-based material includes at least one of silicon, a silicon-oxygen compound, a silicon-carbon compound, or a silicon alloy.
  • the negative electrode active material layer may further include a conductive agent and/or a binder.
  • the conductive agent in the negative electrode active material layer may include at least one of carbon black, acetylene black, Ketjen black, flake graphite, graphene, carbon nanotubes, carbon fibers, or carbon nanowires.
  • the binder in the negative electrode active material layer may include at least one of carboxymethyl cellulose (CMC), polyacrylic acid, polyacrylic acid salt, polyacrylic acid ester, polyvinyl pyrrolidone, polyaniline, polyimide, polyamide-imide, polysiloxane, styrene-butadiene rubber, epoxy resin, polyester resin, polyurethane resin, or polyfluorene.
  • CMC carboxymethyl cellulose
  • polyacrylic acid polyacrylic acid salt
  • polyacrylic acid ester polyvinyl pyrrolidone
  • polyaniline polyimide
  • polyamide-imide polysiloxane
  • styrene-butadiene rubber epoxy resin
  • polyester resin polyurethane resin
  • polyfluorene polyfluorene
  • the positive electrode includes a positive electrode current collector and a positive electrode active material layer disposed on the positive electrode current collector.
  • the positive electrode active material layer may be located on one side or both sides of the positive electrode current collector.
  • the positive electrode current collector may be aluminum foil, and of course, other positive electrode current collectors commonly used in the art may also be used.
  • the thickness of the positive electrode current collector may be 1 ⁇ m to 200 ⁇ m.
  • the positive electrode The active material layer may be coated only on a partial area of the positive electrode current collector.
  • the thickness of the positive electrode active material layer may be 10 ⁇ m to 500 ⁇ m. It should be understood that these are only exemplary and other suitable thicknesses may be used.
  • the positive electrode active material layer includes a positive electrode active material.
  • the positive electrode active material includes LiCoO2 , LiNiO2 , LiMn2O4 , LiCo1 -yMyO2, LiNi1-yMyO2, LiMn2-vMyO4, LiNixCoyMnzM1- xyzO2 , wherein M is selected from at least one of Fe, Co, Ni , Mn, Mg, Cu, Zn , Al, Sn, B, Ga, Cr, Sr , V, or Ti, and 0 ⁇ y ⁇ 1 , 0 ⁇ x ⁇ 1 , 0 ⁇ z ⁇ 1, and x+y+z ⁇ 1.
  • the positive electrode active material may include at least one of lithium cobalt oxide, lithium manganese oxide, lithium iron phosphate, lithium manganese iron phosphate, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, or lithium nickel manganese oxide, and the above positive electrode active materials may be doped and/or coated.
  • the positive electrode active material layer further includes a binder and a conductive agent.
  • the binder in the positive electrode active material layer may include at least one of polyvinylidene fluoride, a copolymer of vinylidene fluoride-hexafluoropropylene, a styrene-acrylate copolymer, a styrene-butadiene copolymer, a polyamide, a polyacrylonitrile, a polyacrylate, a polyacrylic acid, a polyacrylate, sodium carboxymethyl cellulose, polyvinyl acetate, polyvinylpyrrolidone, a polyvinyl ether, polymethyl methacrylate, polytetrafluoroethylene or polyhexafluoropropylene.
  • the conductive agent in the positive electrode active material layer may include at least one of conductive carbon black, acetylene black, Ketjen black, lamellar graphite, graphene, carbon nanotubes or carbon fibers.
  • the mass ratio of the positive electrode active material, the conductive agent and the binder in the positive electrode active material layer may be (70-98): (1-15): (1-15). It should be understood that the above is only an example, and the positive electrode active material layer may adopt any other suitable material, thickness and mass ratio.
  • the separator includes at least one of polyethylene, polypropylene, polyvinylidene fluoride, polyethylene terephthalate, polyimide or aramid.
  • polyethylene includes at least one selected from high-density polyethylene, low-density polyethylene or ultra-high molecular weight polyethylene.
  • polyethylene and polypropylene have a good effect on preventing short circuits and can improve the stability of the battery through the shutdown effect.
  • the thickness of the separator is in the range of about 3 ⁇ m to 500 ⁇ m.
  • the surface of the isolation membrane may further include a porous layer, the porous layer is disposed on at least one surface of the isolation membrane, the porous layer includes at least one of inorganic particles or a binder, the inorganic particles are selected from aluminum oxide ( Al2O3 ), silicon oxide ( SiO2 ), magnesium oxide (MgO), titanium oxide ( TiO2 ), hafnium dioxide ( HfO2 ), tin oxide ( SnO2 ), cerium dioxide ( CeO2 ), nickel oxide (NiO), zinc oxide (ZnO), calcium oxide (CaO), zirconium oxide ( ZrO2 ), yttrium oxide ( Y2O3 ), silicon carbide (SiC), boehmite, aluminum hydroxide, hydroxide At least one of magnesium, calcium hydroxide or barium sulfate.
  • the pores of the isolation membrane have a diameter in the range of about 0.01 ⁇ m to 1 ⁇ m.
  • the binder of the porous layer is selected from at least one of polyvinylidene fluoride, copolymer of vinylidene fluoride-hexafluoropropylene, polyamide, polyacrylonitrile, polyacrylate, polyacrylic acid, polyacrylate, sodium carboxymethyl cellulose, polyvinylpyrrolidone, polyvinyl ether, polymethyl methacrylate, polytetrafluoroethylene or polyhexafluoropropylene.
  • the porous layer on the surface of the isolation membrane can improve the heat resistance, oxidation resistance and electrolyte wetting performance of the isolation membrane, and enhance the adhesion between the isolation membrane and the pole piece.
  • the electrode assembly of the electrochemical device is a wound electrode assembly or a stacked electrode assembly.
  • the electrochemical device is a lithium ion battery, but the present application is not limited thereto.
  • a positive electrode, a separator, and a negative electrode are wound or stacked in sequence to form an electrode assembly, and then packaged in, for example, an aluminum-plastic film housing, injected with an electrolyte, formed, and packaged to form a lithium-ion battery. Then, the prepared lithium-ion battery is subjected to a performance test.
  • the present application also provides an electronic device, which includes the electrochemical device described in the present application.
  • the electronic device of the embodiment of the present application is not particularly limited, and it can be any electronic device known in the prior art.
  • the electronic device may include, but is not limited to, a laptop computer, a pen-input computer, a mobile computer, an e-book player, a portable phone, a portable fax machine, a portable copier, a portable printer, a head-mounted stereo headset, a video recorder, an LCD TV, a portable cleaner, a portable CD player, a mini-disc, a transceiver, an electronic notepad, a calculator, a memory card, a portable recorder, a radio, a backup power supply, a motor, a car, a motorcycle, a power bicycle, a bicycle, a lighting fixture, a toy, a game console, a clock, an electric tool, a flashlight, a camera, a large household battery and a lithium ion capacitor, etc.
  • lithium-ion batteries The preparation of lithium-ion batteries is described below by taking lithium-ion batteries as an example and combining specific embodiments. Those skilled in the art will understand that the preparation method described in this application is only an example, and any other suitable preparation method is within the scope of this application.
  • Lithium cobalt oxide (LiCoO 2 ), conductive carbon black and polyvinylidene fluoride (PVDF) were dissolved in N-methylpyrrolidone (NMP) at a weight ratio of 97.9:0.9:1.2, and stirred and mixed thoroughly to form a positive electrode slurry.
  • NMP N-methylpyrrolidone
  • a 13 ⁇ m aluminum foil was used as a positive electrode current collector.
  • the positive electrode slurry was coated on the positive electrode current collector, and the positive electrode was obtained after drying, cold pressing and cutting.
  • the compacted density of the positive electrode was 4.15 g/cm 3 .
  • the isolation membrane substrate is 5 ⁇ m thick polyethylene (PE), and a 2 ⁇ m thick alumina ceramic layer is coated on both sides of the isolation membrane substrate. Then, 2.5 mg of polyvinylidene fluoride (PVDF) is coated on both sides of the isolation membrane coated with a single ceramic layer, and then dried to obtain an isolation membrane.
  • PE polyethylene
  • PVDF polyvinylidene fluoride
  • ethylene carbonate (EC), propylene carbonate (PC), diethyl carbonate (DEC), ethyl propionate (EP) and propyl propionate (PP) are mixed uniformly in a mass ratio of 1:1:1:1:1, and then the electrolyte salt LiPF6 is dissolved in the above-mentioned non-aqueous solvent. After mixing uniformly, a basic electrolyte is formed, in which the mass percentage of LiPF6 is 12.5%.
  • the positive electrode, the separator, and the negative electrode are stacked in order, so that the separator is between the positive electrode and the negative electrode to play a role of isolation, and then wound to obtain an electrode assembly.
  • the electrode assembly is placed in an outer packaging aluminum plastic film, and after dehydration at 80°C, the above electrolyte is injected and packaged, and a lithium-ion battery is obtained through a process of formation, degassing, and trimming.
  • the lithium-ion battery was charged to 4.5V at 0.7C, and charged to 0.05C at a constant voltage at 4.5V. Then it was discharged to 3.0V at a current of 0.7C, and the cycle was repeated 800 times with a process of charging at 0.7C and discharging at 1C.
  • the discharge capacity of the 3rd and 800th cycles was tested, and the impedance after the 3rd and 300th cycles was tested at 1000Hz.
  • the cycle capacity retention rate and cycle impedance growth rate of the lithium-ion battery were calculated by the following formula:
  • Cycle capacity retention rate discharge capacity at the 800th cycle / discharge capacity at the 3rd cycle ⁇ 100%
  • Cycle impedance growth rate impedance after the 300th cycle/impedance after the 3rd cycle ⁇ 100%.
  • the lithium-ion battery was charged to 4.55V at a constant current of 0.5C, and then charged to a current of 0.05C at a constant voltage.
  • the open circuit voltage was recorded as V0, and the thickness of the lithium-ion battery was recorded as d0.
  • the lithium-ion battery was placed in a 60°C oven for 20 days, and then the thickness was measured and recorded as d, and the test voltage was recorded as V1.
  • the high temperature storage thickness expansion rate and high temperature storage voltage drop of lithium-ion batteries are calculated by the following formula:
  • Table 1 shows the compound of formula IA, compound of formula IB and compound of formula IC in the electrolyte and their content The influence of high temperature storage on the cycling performance and performance of lithium-ion batteries.
  • Comparative Examples 1-4 when the electrolyte contains only one or two of the compounds of formula I-A, formula I-B and formula I-C, the lithium ion battery has a higher cycle impedance growth rate and high temperature storage voltage drop.
  • Comparative Examples 5 and 6 although the electrolyte contains the compounds of formula I-A, formula I-B and formula I-C at the same time, the content of the compound of formula I-A in Comparative Example 5 and the compound of formula I-C in Comparative Example 6 is too high, and the effect of reducing the cycle impedance growth rate of the lithium ion battery is not obvious, and it may even lead to increased costs, and still cannot meet the use requirements.
  • the cycle impedance growth rate and high temperature storage voltage drop of the lithium ion battery are significantly reduced.
  • the content of the compound of formula IA in the electrolyte is in the range of 0.5% to 4.2%
  • the content of the compound of formula IB is in the range of 0.5% to 4.2%
  • the compound of formula IC is When the content is in the range of 0.5% to 3.0%, the cycle impedance growth rate and high temperature storage voltage drop of the lithium-ion battery can be further reduced.
  • the cycle impedance growth rate and high temperature storage voltage drop of the lithium ion battery can be further reduced.
  • Z/X is in the range of 0.6 to 2.5, the cycle impedance growth rate and high temperature storage voltage drop of the lithium ion battery are further optimized.
  • Table 2 shows the effects of sulfur-oxygen double bond compounds, compound IV and boron-containing lithium salts in the electrolyte and their contents on the cycling performance and high-temperature storage performance of lithium-ion batteries.
  • the electrolyte simultaneously contains 0.12%-5.0% of the compound of formula I-A, 0.12%-5.0% of the compound of formula I-B and 0-12%-3.0% of the compound of formula I-C, adding 0-01% to 15% of the compound of formula III to the electrolyte can further improve the cycle capacity retention rate of the lithium ion battery.
  • references to “embodiments”, “partial embodiments”, “one embodiment”, “another example”, “example”, “specific example” or “partial example” throughout the specification mean that at least one embodiment or example in the present application includes the specific features, structures, materials or characteristics described in the embodiment or example. Therefore, descriptions appearing in various places throughout the specification, such as: “in some embodiments”, “in an embodiment”, “in one embodiment”, “in another example”, “in an example”, “in a specific example” or “example”, do not necessarily refer to the same embodiment or example in the present application.
  • the specific features, structures, materials or characteristics herein may 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电化学装置。具体而言，本申请提供一种电解液，其包括式Ⅰ-A化合物、式Ⅰ-B化合物和式Ⅰ-C化合物，并且其中基于所述电解液的质量，所述式Ⅰ-A化合物的含量为0.12％-5.0％；所述式I-B化合物的含量为0.12％-5.0％；以及所述式I-C化合物的含量为0.12％至3.0％。本申请的电解液有助于改善电化学装置的循环性能和高温存储性能。

Description

电解液和电化学装置 技术领域
本申请涉及储能领域，具体涉及一种电解液和电化学装置。
背景技术
随着电化学装置(例如，锂离子电池)在各类电子产品中的广泛应用，用户对于电化学装置的性能提出了越来越高的要求，尤其关注于电化学装置的长循环寿命以及自放电大小等。电化学装置的寿命会受其循环过程的阻抗增长的影响，电化学装置在高温存储过程的电压降能反应出其自放电情况。
电化学装置在循环过程中阻抗的增长和高温存储过程中电压降的影响因素包括活性材料界面与电解液界面之间的稳定性。当其界面之间的稳定性较差时，电解液会持续分解。提高活性材料界面与电解液界面之间的稳定性从而抑制电解液分解已成为目前亟待解决的问题之一。
有鉴于此，确有必要提供一种可提供改进的循环性能和高温存储性能的电解液和电化学装置。
发明内容
本申请通过提供一种电解液和电化学装置以试图在至少某种程度上解决至少一种存在于相关领域中的问题。
根据本申请的一个方面，本申请提供了一种电解液，包括式I-A化合物、式I-B化合物和式I-C化合物：
其中：
n选自1-8的整数；
R11、R12、R13和R14各自独立地选自氢、卤素或经取代或未经取代的C1-C5烷基，且R11、R12、R13和R14中的至少一者是经取代或未经取代的C1-C5烷基；
R15选自C2-C4亚烷基、C2-C4亚烯基、
R17、R18和R19各自独立选自单键、C1-C5亚烷基或C1-C5亚烷氧基；
经取代时，取代基各自独立地为卤素；并且
表示两个相邻原子的连接位点；
并且其中基于电解液的质量，
式I-A化合物的含量为X％，X在0.12至5.0的范围内；
式I-B化合物的含量为Y％，Y在0.12至5.0的范围内；以及
式I-C化合物的含量为Z％，Z在0.12至3.0的范围内。
式I-A化合物、式I-B化合物和式I-C化合物均为多腈化合物。多个氰基的存在可以稳定正极活性材料(例如，正极活性材料中的过渡金属)。式I-A化合物存在支链，其会增加空间位阻，增强对正极界面的保护，但其粘度较大。式I-B化合物具有较小的粘度。式I-C化合物对正极活性材料的稳定性强。电解液中包含特定含量的式I-A化合物、式I-B化合物和式I-C化合物，能有效改善包含该电解液的电化学装置的循环性能和高温存储性能。
根据本申请的实施例，所述X在0.5至4.2的范围内；所述Y在0.5至4.2的范围内；以及所述Z在0.5至3.0的范围内。
根据本申请的实施例，Z/X在0.1至3的范围内。
根据本申请的实施例，Z/X在0.6至2.5的范围内。
根据本申请的实施例，所述式I-A化合物包括以下化合物中的至少一种：




根据本申请的实施例，所述式I-B化合物包括以下化合物中的至少一种：
根据本申请的实施例，所述式I-C化合物包括以下化合物中的至少一种：
根据本申请的实施例，Y/X在0.12至5的范围内。
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，并且基于所述电解液的质量，所述含硫氧双键的化合物的含量为0.01％至10％。
根据本申请的实施例，所述含硫氧双键的化合物包括具有式II的化合物：
其中：
R21和R22各自独立地选自经取代或未经取代的C1-C5烷基、经取代或未经取代的C2-C10烯基、经取代或未经取代的C2-C10炔基、经取代或未经取代的C3-C10脂环基、经取代或未经取代的C6-C10芳基或经取代或未经取代的含有C1-C5的杂原子官能团，所述杂原子官能团中的杂原子选自O或S中的至少一种；
R21和R22任选地连接在一起形成环；并且
当经取代时，取代基各自独立地选自卤素。
根据本申请的实施例，所述含硫氧双键的化合物包括以下化合物中的至少一种：

当电解液进一步包括一定含量的含硫氧双键的化合物时，可以有效地改善正极界面和负极界面的稳定性，且不会显著影响电解液的粘度和正极界面和负极界面的阻抗，可进一步改善电化学装置的循环性能和高温存储性能。
根据本申请的实施例，所述电解液还包括式III化合物：
其中：
R31选自经取代或未经取代的C1-C6亚烷基或经取代或未经取代的C2-C6亚烯基；
当经取代时，取代基各自独立地选自卤素、C1-C6烷基或C2-C6烯基；并且
基于所述电解液的质量，所述式III化合物的含量为0.01％至15％。
根据本申请的实施例，所述式III化合物包括以下化合物中的至少一种：
当电解液进一步包括一定含量的式III化合物时，可充分保护负极界面，进一步改善电化学装置的循环性能和高温存储性能。
根据本申请的实施例，所述电解液还包括化合物IV，所述化合物IV包括以下化合物中的至少一种：

根据本申请的实施例，基于所述电解液的质量，所述化合物IV的含量为0.01％至2％。
当电解液进一步包括一定含量的化合物IV时，可进一步抑制电解液分解，减少电化学装置的循环阻抗增长和高温存储厚度膨胀率，从而显著提升电化学装置的循环性能和高温存储性能。
根据本申请的实施例，所述电解液还包括含硼锂盐，并且基于所述电解液的质量，所述含硼锂盐的含量为0.01％至1％。
根据本申请的实施例，所述含硼锂盐包括四氟硼酸锂、二草酸硼酸锂或二氟草酸硼酸锂中的至少一种。
根据本申请的实施例，基于所述电解液的质量，所述含硼锂盐的含量为M％，并且M/X不大于1。
当电解液中进一步包含一定含量的含硼锂盐时，可进一步减少电化学装置的循环阻抗增长，并进一步显著提升电化学装置的循环性能。
根据本申请的另一个方面，本申请提供了一种电化学装置，其包括正极、负极和根据本申请所述的电解液。
根据本申请的又一个方面，本申请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。
本申请提供了一种电解液、电化学装置和电子装置，当电解液中同时包含特定含量的式I-A化合物、式I-B化合物和式I-C化合物时，电解液具有恰当的粘度并且可稳定正极活性材料，保护正极界面，起到抑制电解液分解的作用，从而可显著减少电化学装置的循环阻抗增长和高温存储电压降，由此显著提升电化学装置的循环性能和高温存储性能，同时可获得较小粘度的电解液，提升了电化学装置的动力学性能。
本申请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。
在具体实施方式及权利要求书中，由术语“中的至少一种”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中的至少一种”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中的至少一种”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“烷基”是指具有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)-C2-4烯基、-C2-6烯基及-C2-10烯基。代表性烯基包括(例如)乙烯基、正丙烯基、异丙烯基、正-丁-2-烯基、丁-3-烯基、正-己-3-烯基等。
术语“炔基”是指可为直链或具支链且具有至少一个且通常具有1个、2个或3个碳碳三键的单价不饱和烃基团。除非另有定义，否则所述炔基通常含有2个到20个碳原子且包括(例如)-C2-4炔基、-C3-6炔基及-C3-10炔基。代表性炔基包括(例如)乙炔基、丙-2-炔基(正-丙炔基)、正-丁-2-炔基、正-己-3-炔基等。
术语“亚烷基”涵盖直链和支链亚烷基。例如，亚烷基可为C1-C50亚烷基、C1-C40亚烷基、C1-C30亚烷基、C1-C20亚烷基、C1-C10亚烷基、C1-C6亚烷基、C2-C6亚烷基、C2-C5亚烷基。
术语“亚烯基”涵盖直链和支链亚烯基。例如，亚烯基可为C2-C50亚烯基、C2-C40亚烯基、C2-C30亚烯基、C2-C20亚烯基、C2-C10亚烯基、C1-C6亚烯基、C2-C6亚烯基。
术语“芳基”意指具有单环(例如，苯基)或稠合环的单价芳香族烃。稠合环系统包括那些完全不饱和的环系统(例如，萘)以及那些部分不饱和的环系统(例如，1，2，3，4-四氢萘)。除非另有定义，否则所述芳基通常含有6个到26个碳环原子且包括(例如)-C6-10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“卤素”可为F、Cl、Br或I。
术语“杂原子”涵盖O、S、P、N、B或其电子等排体。
术语“杂原子的官能团”是指包含杂原子的官能团，其中杂原子包含O、S、P、N或B元素中的至少一种。杂原子的官能团的实例包括但不限于：C0-C5的磺酸酯基、C0-C5的硫酸酯基、C0-C5的醚基、C0-C5的亚磺酸酯基、C0-C5的亚硫酸酯基、C0-C5的磷酸酯基、C0-C5的硼酸酯基等。
术语“脂环基”是指饱和、部分不饱和或不饱和的单、二、三或多环基团，其具有大约3至15个碳，或者具有3至12个碳，或者3至8个碳，或者3至6个碳，或者5或6个碳。脂环基的实例包括但不限于：环丙基，环丁基，环丁烯基，环戊基，环戊烯基，环己基，环己烯基，环庚基，环辛基，等等。
随着电化学装置(例如，锂离子电池)的广泛应用，人们对其性能的要求越来越高。提高电化学装置的能量密度的主要方法包括提高电化学装置的充电电压。然而，当提高电化学装置的充电电压时，较高的充电电压会加速正极活性材料(例如，其中的高价态的过渡金属)对电解液的氧化分解，还会导致释氧，进一步加速电解液的分解，从而使电化学装置的产气增加，进而影响电化学装置的循环性能和高温存储性能。
为了改善电化学装置的循环性能和高温存储性能，本申请提供了一种电解液，其包括式I-A化合物、式I-B化合物和式I-C化合物：

其中：
n选自1-8的整数；
R11、R12、R13和R14各自独立地选自氢、卤素或经取代或未经取代的C1-C5烷基，且R11、R12、R13和R14中的至少一者是经取代或未经取代的C1-C5烷基；
R15选自C2-C4亚烷基、C2-C4亚烯基、
R17、R18和R19各自独立选自单键、C1-C5亚烷基或C1-C5亚烷氧基；
经取代时，取代基各自独立地为卤素；并且
表示两个相邻原子的连接位点；
并且其中基于所述电解液的质量，
所述式I-A化合物的含量为X％，X在0.12至5.0的范围内；
所述式I-B化合物的含量为Y％，Y在0.12至5.0的范围内；以及
所述式I-C化合物的含量为Z％，Z在0.12至3.0的范围内。
式I-A化合物、式I-B化合物和式I-C化合物均为多腈化合物。多个氰基的存在可以稳定正极活性材料(例如，正极活性材料中的过渡金属)。式I-A化合物存在支链，其会增加空间位阻，增强对正极界面的保护，但其粘度较大。式I-B化合物具有较小的粘度。式I-C化合物对正极活性材料的稳定性强。当电解液中式I-A化合物、式I-B化合物和式I-C化合物的含量太低时，其难以发挥有效作用。随着电解液中式I-A化合物、式I-B化合物和式I-C化合物的含量的增加，其显示出对电化学装置的循环阻抗增长和高温存储电压降的改善效果，然而继续增加电解液中式I-A化合物、式I-B化合物和式I-C化合物的含量难以继续提升其效果。过量的式I-A化合物反而会增大电解液的粘度，从而对电化学装置的动力学性能产生不利影响。当电解液中同时包含特定含量的式I-A化合物、式I-B化合物和式I-C化合物时，电解液具有恰当的粘度并且可稳定正极活性材料，保护正极界面，起到抑制电解液分解的作用，从而可显著减少电化学装置的循环阻抗增长和 高温存储电压降，由此显著提升电化学装置的循环性能和高温存储性能，同时可获得较小粘度的电解液，提升了电化学装置的动力学性能。
在一些实施例中，X在0.2至4.5的范围内。在一些实施例中，X在0.5至4.2的范围内。在一些实施例中，X在1.0至4.0的范围内。在一些实施例中，X在1.5至3.5的范围内。在一些实施例中，X在2.0至3.0的范围内。在一些实施例中，X为0.12、0.2、0.5、1.0、1.5、2.0、2.5、3.0、3.5、4.0、4.5、5.0或在上述任意两个数值所组成的范围内。
在一些实施例中，Y在0.2至4.5的范围内。在一些实施例中，Y在0.5至4.2的范围内。在一些实施例中，Y在1.0至4.0的范围内。在一些实施例中，Y在1.5至3.5的范围内。在一些实施例中，Y在2.0至3.0的范围内。在一些实施例中，Y为0.12、0.2、0.5、1.0、1.5、2.0、2.5、3.0、3.5、4.0、4.5、5.0或在上述任意两个数值所组成的范围内。
在一些实施例中，Z在0.2至2.5的范围内。在一些实施例中，Z在0.5至2.0的范围内。在一些实施例中，Z在1.0至1.5的范围内。在一些实施例中，Z为0.12、0.2、0.5、1.0、1.5、2.0、2.5、3.0或在上述任意两个数值所组成的范围内。
在一些实施例中，所述式I-A化合物包括以下化合物中的至少一种：




在一些实施例中，所述式I-B化合物包括以下化合物中的至少一种：
在一些实施例中，所述式I-C化合物包括以下化合物中的至少一种：

在一些实施例中，Z/X在0.1至3的范围内。在一些实施例中，Z/X在0.3至2.8的范围内。在一些实施例中，Z/X在0.6至2.5的范围内。在一些实施例中，Z/X在1至2的范围内。在一些实施例中，Z/X为0.1、0.5、0.6、1、1.5、2、2.5、3或在上述任意两个数值所组成的范围内。当Z/X在上述范围内时，可进一步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，Y/X在0.12至5的范围内。在一些实施例中，Y/X在0.5至4.5的范围内。在一些实施例中，Y/X在1至4的范围内。在一些实施例中，Y/X在1.5至3.5的范围内。在一些实施例中，Y/X在2至3的范围内。在一些实施例中，Y/X为0.12、0.2、0.5、1、1.5、2、2.5、3、3.5、4、4.5、5或在上述任意两个数值所组成的范围内。当Y/X在上述范围内时，可进一步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，所述电解液还包括含硫氧双键的化合物，并且基于所述电解液的质量，所述含硫氧双键的化合物的含量为0.01％至10％。在一些实施例中，基于所述电解液的质量，所述含硫氧双键的化合物的含量为0.05％至8％。在一些实施例中，基于所述电解液的质量，所述含硫氧双键的化合物的含量为0.1％至6％。在一些实施例中，基于所述电解液的质量，所述含硫氧双键的化合物的含量为0.5％至5％。在一些实施例中，基于所述电解液的质量，所述含硫氧双键的化合物的含量为1％至4％。在一些实施例中，基于所述电解液的质量，所述含硫氧双键的化合物的含量为2％至3％。在一些实施例中，基于所述电解液的质量，所述含硫氧双键的化合物的含量为0.01％、0.05％、0.1％、0.5％、1％、2％、3％、4％、5％、6％、7％、8％、9％、10％或在上述任意两个数值所组成的范围内。
在一些实施例中，所述含硫氧双键的化合物包括具有式II的化合物：
其中：
R21和R22各自独立地选自经取代或未经取代的C1-C5烷基、经取代或未经取代的C2-C10烯基、经取代或未经取代的C2-C10炔基、经取代或未经取代的C3-C10脂环基、经取代或未经取代的C6-C10芳基或经取代或未经取代的含有C1-C5的杂原子官能团，所述杂原子官能团中的杂原子选自O或S中的至少一种；
R21和R22任选地连接在一起形成环；并且
当经取代时，取代基各自独立地选自卤素。
在一些实施例中，R21和R22任选地连接在一起形成5元环或6元环。在一些实施例中，R21和R22任选地连接在一起形成5元环状砜、6元环环状砜、5元状硫酸酯、6元环硫酸酯、5元环状磺酸酯、6元磺酸酯、5元环状磺酸酐或6元状磺酸酐等。
在一些实施例中，所述含硫氧双键的化合物包括以下化合物中的至少一种：
一方面，含硫氧双键化合物具有较强的抗氧化能力，可以提高正极界面的稳定性。另一方面，含硫氧双键化合物可以在负极表面还原，形成一层保护膜，抑制电解液的分解，进一步增强负极界面的稳定性。当电解液进一步包括一定含量的含硫氧双键的化合物时，不仅可以有效地改善正极界面和负极界面的稳定性，而且不会显著影响电解液的粘度和正极界面和负极界面的阻抗，由此可进一步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，所述电解液还包括式III化合物：
其中：
R31选自经取代或未经取代的C1-C6亚烷基或经取代或未经取代的C2-C6亚烯基；
当经取代时，取代基各自独立地选自卤素、C1-C6烷基或C2-C6烯基；并且
基于所述电解液的质量，所述式III化合物的含量为0.01％至15％。
在一些实施例中，基于所述电解液的质量，所述式III化合物的含量为0.05％至12％。在一些实施例中，基于所述电解液的质量，所述式III化合物的含量为0.1％至10％。在一些实施例中，基于所述电解液的质量，所述式III化合物的含量为0.5％至8％。在一些实施例中，基于所述电解液的质量，所述式III化合物的含量为1％至5％。在一些实施例中，基于所述电解液的质量，所述式III化合物的含量为2％至4％。在一些实施例中，基于所述电解液的质量，所述式III化合物的含量为0.01％、0.05％、0.1％、0.5％、1％、2％、3％、4％、5％、6％、7％、8％、9％、10％、11％、12％、13％、14％、15％或在上述任意两个数值所组成的范围内。
在一些实施例中，所述式III化合物包括以下化合物中的至少一种：
式III化合物可以辅助增强负极固态界面膜(SEI)的成膜稳定性，增加SEI膜的柔性，增强对负极活性材料的保护作用，降低负极活性材料与电解液的界面接触几率，从而降低电化学装置在循环过程中的阻抗。当电解液进一步包括一定含量的式III化合物时，可充分保护负极界面，进一步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，所述电解液还包括化合物IV，所述化合物IV包括以下化合物中的至少一种：
化合物IV包含至少3个氰基(-CN)，其对正极界面具有更强的保护作用。化合物IV能够与电解液中的式I-A化合物、式I-B化合物和式I-C化合物共同作用，进一步抑制电解液分解，从而进一步减少电化学装置的循环阻抗增长和高温存储厚度膨胀率，并进一步显著提升电化学装置的循环性能和高温存储性能。
在一些实施例中，基于所述电解液的质量，所述化合物IV的含量为0.01％至2％。在一些实施例中，基于所述电解液的质量，所述化合物IV的含量为0.05％至1.5％。在一些实施例中，基于所述电解液的质量，所述化合物IV的含量为0.1％至1％。在一些实施例中，基于所述电解液的质量，所述化合物IV的含量为0.2％至0.5％。在一些实施例中，基于所述电解液的质量，所述化合物IV的含量为0.01％、0.05％、0.1％、0.5％、1％、1.5％、2％或在上述任意两个数值所组成的范围内。当电解液中化合物IV的含量在上述范围内时，可进一步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，所述电解液还包括含硼锂盐，并且基于所述电解液的质量，所述含硼锂盐的含量为0.01％至1％。在一些实施例中，基于所述电解液的质量，所述含硼锂盐的含量为0.05％至0.8％。在一些实施例中，基于所述电解液的质量，所述含硼锂盐的含量为0.1％至0.6％。在一些实施例中，基于所述电解液的质量，所述含硼锂盐的含量为0.2％至0.5％。在一些实施例中，基于所述电解液的质量，所述含硼锂盐的含量为0.01％、0.05％、0.1％、0.2％、0.3％、0.4％、0.5％、0.6％、0.7％、0.8％、0.9％、1％或在上述任意两个数值所组成的范围内。
在一些实施例中，所述含硼锂盐包括四氟硼酸锂、二草酸硼酸锂或二氟草酸 硼酸锂中的至少一种。
含硼锂盐可以在正极成膜，其可与式I-A化合物、式I-B化合物和式I-C化合物共同作用以稳定正极界面。当电解液中进一步包含一定含量的含硼锂盐时，可进一步减少电化学装置的循环阻抗增长，并进一步显著提升电化学装置的循环性能。
在一些实施例中，基于所述电解液的质量，所述含硼锂盐的含量为M％，并且M/X不大于1。在一些实施例中，M/X为0.01至0.8。在一些实施例中，M/X为0.05至0.6。在一些实施例中，M/X为0.1至0.5。在一些实施例中，M/X为0.2至0.4。在一些实施例中，M/X为0.01、0.02、0.05、0.1、0.2、0.3、0.4、0.5、0.6、0.7、0.8、0.9、1或在上述任意两个数值所组成的范围内。当M/X在上述范围内时，可进一步显著提升电化学装置的循环性能和高温存储性能。
在一些实施例中，电解液还可以包括其他非水有机溶剂和电解质盐。非水有机溶剂可以包含碳酸酯、羧酸酯、醚类或其他非质子溶剂中的至少一种。碳酸酯类溶剂的示例包括碳酸二甲酯、碳酸二乙酯、碳酸甲乙酯、碳酸甲丙酯、碳酸乙丙酯、碳酸二丙酯、碳酸乙烯酯、碳酸丙烯酯、碳酸丁烯酯、二(2，2，2-三氟乙基)碳酸酯等。羧酸酯类溶剂的示例包括乙酸甲酯、乙酸乙酯、乙酸正丙酯、乙酸正丁酯、丙酸甲酯、丙酸乙酯、丙酸丙酯、丙酸丁酯、丁酸甲酯、丁酸乙酯、丁酸丙酯、丁酸丁酯、γ-丁内酯、乙酸2，2-二氟乙酯、戊内酯、丁内酯、2-氟乙酸乙酯、2，2-二氟乙酸乙酯、三氟乙酸乙酯、2，2，3，3，3-五氟丙酸乙酯、2，2，3，3，4，4，4，4-七氟丁酸甲酯、4，4，4-三氟-3-(三氟甲基)丁酸甲酯、2，2，3，3，4，4，5，5，5，5-九氟戊酸乙酯、2，2，3，3，4，4，5，5，6，6，7，7，8，8，9，9，9-十七氟壬酸甲酯、2，2，3，3，4，4，5，5，6，6，7，7，8，8，9，9，9-十七氟壬酸乙酯等。醚类溶剂的示例包括乙二醇二甲醚、二乙二醇二甲醚、四乙二醇二甲醚、二丁醚、四氢呋喃、2-甲基四氢呋喃、双(2，2，2-三氟乙基)醚等。
在一些实施例中，电解质盐包括有机锂盐或无机锂盐中的至少一种。在一些实施例中，电解质盐包括六氟磷酸锂LiPF6、双三氟甲烷磺酰亚胺锂LiN(CF3SO2)2(简写为LiTFSI)、双(氟磺酰)亚胺锂Li(N(SO2F)2)(简写为LiFSI)或六氟铯酸锂(LiCsF6)、高氯酸锂LiClO4、三氟甲磺酸锂LiCF3SO3中的至少一种。
在一些实施例中，基于电解液的质量，电解质盐的含量为10％至15％。在一些实施例中，基于电解液的质量，电解质盐的质量百分含量为12％至15％。 当电解质盐的含量在上述范围内时，电解液具有合适的离子电导率和粘度，使得电化学装置具有良好的倍率性能和循环性能。
本申请还提供了一种电化学装置。电化学装置包括电极组件和电解液，电极组件包括正极、负极、设置在正极和负极之间的隔离膜。在一些实施例中，所述电解液为本申请所描述的电解液。
在一些实施例中，负极可以包括负极集流体和设置在负极集流体上的负极活性材料层。负极活性材料层可以设置在负极集流体的一侧或两侧上。在一些实施例中，负极集流体可以采用铜箔、铝箔、镍箔或碳基集流体中的至少一种。在一些实施例中，负极集流体的厚度可以为1μm至200μm。在一些实施例中，负极活性材料层可以仅涂覆在负极集流体的部分区域上。在一些实施例中，负极活性材料层的厚度可以为10μm至500μm。应该理解，这些仅是示例性的，可以采用其他合适的厚度。
在一些实施例中，负极活性材料层包括负极活性材料。在一些实施例中，负极活性材料层中的负极活性材料包括锂金属、天然石墨、人造石墨或硅基材料中的至少一种。在一些实施例中，硅基材料包括硅、硅氧化合物、硅碳化合物或硅合金中的至少一种。
在一些实施例中，负极活性材料层中还可以包括导电剂和/或粘结剂。负极活性材料层中的导电剂可以包括炭黑、乙炔黑、科琴黑、片层石墨、石墨烯、碳纳米管、碳纤维或碳纳米线中的至少一种。在一些实施例中，负极活性材料层中的粘结剂可以包括羧甲基纤维素(CMC)、聚丙烯酸、聚丙烯酸盐、聚丙烯酸酯、聚乙烯基吡咯烷酮、聚苯胺、聚酰亚胺、聚酰胺酰亚胺、聚硅氧烷、丁苯橡胶、环氧树脂、聚酯树脂、聚氨酯树脂或聚芴中的至少一种。应该理解，以上公开的材料仅是示例性，负极活性材料层可以采用任何其他合适的材料。在一些实施例中，负极活性材料层中的负极活性材料、导电剂和粘结剂的质量比可以为(80-99)∶(0-5-10)∶(0-5-10)。应该理解，这仅是示例性的，而不用于限制本申请。
在一些实施例中，正极包括正极集流体和设置在正极集流体上的正极活性材料层。正极活性材料层可以位于正极集流体一侧或两侧上。在一些实施例中，正极集流体可以采用铝箔，当然，也可以采用本领域常用的其他正极集流体。在一些实施例中，正极集流体的厚度可以为1μm至200μm。在一些实施例中，正极 活性材料层可以仅涂覆在正极集流体的部分区域上。在一些实施例中，正极活性材料层的厚度可以为10μm至500μm。应该理解，这些仅是示例性的，可以采用其他合适的厚度。
在一些实施例中，正极活性材料层包括正极活性材料。在一些实施例中，正极活性材料包括LiCoO2、LiNiO2、LiMn2O4、LiCo1-yMyO2、LiNi1-yMyO2、LiMn2-vMyO4、LiNixCoyMnzM1-x-y-zO2，其中M选自Fe、Co、Ni、Mn、Mg、Cu、Zn、Al、Sn、B、Ga、Cr、Sr、V或Ti中的至少一种，且0≤y≤1，0≤x≤1，0≤z≤1，x+y+z≤1。在一些实施例中，正极活性材料可以包括钴酸锂、锰酸锂、磷酸铁锂、磷酸锰铁锂、镍钴锰酸锂、镍钴铝酸锂或镍锰酸锂中的至少一种，上述正极活性材料可以经过掺杂和/或包覆处理。
在一些实施例中，正极活性材料层还包括粘结剂和导电剂。在一些实施例中，正极活性材料层中的粘结剂可以包括聚偏氟乙烯、偏氟乙烯-六氟丙烯的共聚物、苯乙烯-丙烯酸酯共聚物、苯乙烯-丁二烯共聚物、聚酰胺、聚丙烯腈、聚丙烯酸酯、聚丙烯酸、聚丙烯酸盐、羧甲基纤维素钠、聚醋酸乙烯酯、聚乙烯呲咯烷酮、聚乙烯醚、聚甲基丙烯酸甲酯、聚四氟乙烯或聚六氟丙烯中的至少一种。在一些实施例中，正极活性材料层中的导电剂可以包括导电炭黑、乙炔黑、科琴黑、片层石墨、石墨烯、碳纳米管或碳纤维中的至少一种。在一些实施例中，正极活性材料层中的正极活性材料、导电剂和粘结剂的质量比可以为(70-98)∶(1-15)∶(1-15)。应该理解，以上所述仅是示例，正极活性材料层可以采用任何其他合适的材料、厚度和质量比。
在一些实施例中，隔离膜包括聚乙烯、聚丙烯、聚偏氟乙烯、聚对苯二甲酸乙二醇酯、聚酰亚胺或芳纶中的至少一种。例如，聚乙烯包括选自高密度聚乙烯、低密度聚乙烯或超高分子量聚乙烯中的至少一种。尤其是聚乙烯和聚丙烯，它们对防止短路具有良好的作用，并可以通过关断效应改善电池的稳定性。在一些实施例中，隔离膜的厚度在约3μm至500μm的范围内。
在一些实施例中，隔离膜表面还可以包括多孔层，多孔层设置在隔离膜的至少一个表面上，多孔层包括无机颗粒或粘结剂中的至少一种，无机颗粒选自氧化铝(Al2O3)、氧化硅(SiO2)、氧化镁(MgO)、氧化钛(TiO2)、二氧化铪(HfO2)、氧化锡(SnO2)、二氧化铈(CeO2)、氧化镍(NiO)、氧化锌(ZnO)、氧化钙(CaO)、氧化锆(ZrO2)、氧化钇(Y2O3)、碳化硅(SiC)、勃姆石、氢氧化铝、氢氧化 镁、氢氧化钙或硫酸钡中的至少一种。在一些实施例中，隔离膜的孔具有在约0.01μm至1μm的范围的直径。多孔层的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、羧甲基纤维素钠、聚乙烯呲咯烷酮、聚乙烯醚、聚甲基丙烯酸甲酯、聚四氟乙烯或聚六氟丙烯中的至少一种。隔离膜表面的多孔层可以提升隔离膜的耐热性能、抗氧化性能和电解质浸润性能，增强隔离膜与极片之间的粘接性。
在本申请的一些实施例中，电化学装置的电极组件为卷绕式电极组件或堆叠式电极组件。在一些实施例中，电化学装置为锂离子电池，但是本申请不限于此。
在本申请的一些实施例中，以锂离子电池为例，将正极、隔离膜、负极按顺序卷绕或堆叠成电极组件，之后装入例如铝塑膜壳体中进行封装，注入电解液，化成、封装，即制成锂离子电池。然后，对制备的锂离子电池进行性能测试。
本领域的技术人员将理解，以上描述的电化学装置(例如，锂离子电池)的制备方法仅是实施例。在不背离本申请公开的内容的基础上，可以采用本领域常用的其他方法。
本申请还提供了一种电子装置，其包括本申请所描述的电化学装置。本申请实施例的电子装置没有特别限定，其可以是用于现有技术中已知的任何电子装置。在一些实施例中，电子装置可以包括，但不限于，笔记本电脑、笔输入型计算机、移动电脑、电子书播放器、便携式电话、便携式传真机、便携式复印机、便携式打印机、头戴式立体声耳机、录像机、液晶电视、手提式清洁器、便携CD机、迷你光盘、收发机、电子记事本、计算器、存储卡、便携式录音机、收音机、备用电源、电机、汽车、摩托车、助力自行车、自行车、照明器具、玩具、游戏机、钟表、电动工具、闪光灯、照相机、家庭用大型蓄电池和锂离子电容器等。
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
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。
一、锂离子电池的制备
1、正极的制备
将钴酸锂(LiCoO2)、导电炭黑和聚偏二氟乙烯(PVDF)按照重量比为97.9∶0.9∶1.2溶于N-甲基吡咯烷酮(NMP)中，充分搅拌混合均匀，形成正极浆料。采用13μm的铝箔作为正极集流体。将正极浆料涂覆于正极集流体上，经过干燥、冷压、裁切后得到正极。正极的压实密度为4.15g/cm3。
2、负极的制备
将人造石墨、丁苯橡胶(SBR)和羧甲基纤维素钠(CMC)按重量比97.4∶1.4∶1.2溶于去离子水中，形成负极浆料。采用10μm厚度铜箔作为负极集流体。将负极浆料涂覆于负极集流体上，干燥、冷压、裁切后得到负极。负极的压实密度为1.8g/cm3。
3、隔离膜的制备
隔离膜基材为5μm厚的聚乙烯(PE)，在隔离膜基材的两面上分别涂覆厚度为2μm的氧化铝陶瓷层，然后在涂布单层陶瓷层的隔离膜的两面上各涂覆2.5mg的聚偏二氟乙烯(PVDF)，烘干，得到隔离膜。
4、电解液的制备
在含水量小于10ppm的环境下，将碳酸乙烯酯(EC)、碳酸丙烯酯(PC)、碳酸二乙酯(DEC)、丙酸乙酯(EP)和丙酸丙酯(PP)按照1∶1∶1∶1∶1的质量比混合均匀，再将电解质盐LiPF6溶解于上述非水溶剂，混合均匀后形成基础电解液，其中LiPF6的质量百分含量为12.5％。
根据以下各实施例或对比例的设置向基础电解液中加入一定量的添加剂，得到各实施例或对比例的电解液。
各实施例或对比例中使用的添加剂如下表所示：

5、锂离子电池的制备
将正极、隔离膜、负极按顺序依次叠好，使隔离膜处于正极和负极中间起到隔离的作用，并卷绕得到电极组件。将电极组件置于外包装铝塑膜中，在80℃下脱去水分后，注入上述电解液并封装，经过化成，脱气，切边等工艺流程得到锂离子电池。
二、测试方法
1、锂离子电池的循环性能的测试方法
在25℃条件下，将锂离子电池以0.7C充电至4.5V，4.5V条件下恒压充电至0.05C。之后以0.7C的电流放电至3.0V，并以0.7C充电和1C放电的流程，循环进行800次。测试第3次和第800次循环的放电容量，并在1000Hz条件下测试第3圈循环后和第300次循环后的阻抗。通过下式计算锂离子电池的循环容量保持率和循环阻抗增长率：
循环容量保持率＝第800次循环的放电容量/第3次循环的放电容量×100％，
循环阻抗增长率＝第300次循环后的阻抗/第3次循环后的阻抗×100％。
2、锂离子电池的高温存储性能的测试方法
在25℃条件下，将锂离子电池以0.5C恒流充电至4.55V，然后恒压充电至电流为0.05C，测试开路电压记为V0，测试锂离子电池的厚度并记为d0。将锂离子电池放置到60℃烘箱当中20天，然后测量厚度记为d，测试电压记为V1。
通过下式计算锂离子电池的高温存储厚度膨胀率和高温存储电压降：
高温存储厚度膨胀率＝(d-d0)/d0×100％，
高温存储电压降＝V0-V1。
当锂离子电池的厚度膨胀率超过50％，停止测试。
三、测试结果
表1展示了电解液中式I-A化合物、式I-B化合物和式I-C化合物及其含量对 锂离子电池的循环性能和高温存储性能的影响。
表1

如对比例1-4所示，当电解液仅包含式I-A化合物、式I-B化合物和式I-C化合物中的一种或两种时，锂离子电池具有较高的循环阻抗增长率和高温存储电压降。如对比例5和6所示，虽然电解液同时包含式I-A化合物、式I-B化合物和式I-C化合物，但对比例5中的式I-A化合物，对比例6中的式I-C化合物的含量过高，对降低锂离子电池的循环阻抗增长率的作用不明显，甚至会可能会导致成本升高，仍无法满足使用需求。
如实施例1-25所示，当电解液同时包含0.12％-5.0％的式I-A化合物、0.12％-5.0％的式I-B化合物和0.12％-3.0％的式I-C化合物时，锂离子电池的循环阻抗增长率和高温存储电压降显著降低。当电解液中式I-A化合物的含量在0.5％至4.2％的范围内、式I-B化合物的含量在0.5％至4.2％的范围内且式I-C化合物 的含量在0.5％至3.0％的范围内时，可进一步降低锂离子电池的循环阻抗增长率和高温存储电压降。
当电解液式I-C化合物的含量(Z％)与式I-A化合物的含量(X％)满足Z/X在0.1至3.0的范围内时，可进一步降低锂离子电池的循环阻抗增长率和高温存储电压降。当Z/X在0.6至2.5的范围内时，锂离子电池的循环阻抗增长率和高温存储电压降得到进一步优化。
当电解液式I-B化合物的含量(Y％)与式I-A化合物的含量(X％)满足Y/X在0.12至5.0的范围内时，可进一步降低锂离子电池的循环阻抗增长率和高温存储电压降。
表2展示了电解液中含硫氧双键化合物、化合物IV和含硼锂盐及其含量对锂离子电池的循环性能和高温存储性能的影响。


在电解液同时包含0.12％-5.0％的式I-A化合物、0.12％-5-0％的式I-B化合物和0-12％-3-0％的式I-C化合物的基础上，在电解液中添加0-01％至15％的式III化合物可进一步改善锂离子电池的循环容量保持率。
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 (20)

  1. 一种电解液，其包括式Ⅰ-A化合物、式Ⅰ-B化合物和式Ⅰ-C化合物：
    其中：
    n选自1-8的整数；
    R11、R12、R13和R14各自独立地选自氢、卤素或经取代或未经取代的C1-C5烷基，且R11、R12、R13和R14中的至少一者是经取代或未经取代的C1-C5烷基；
    R15选自C2-C4亚烷基、C2-C4亚烯基、
    R17、R18和R19各自独立选自单键、C1-C5亚烷基或C1-C5亚烷氧基；
    经取代时，取代基各自独立地为卤素；并且
    表示两个相邻原子的连接位点；
    并且其中基于所述电解液的质量，
    所述式I-A化合物的含量为X％，X在0.12至5.0的范围内；
    所述式I-B化合物的含量为Y％，Y在0.12至5.0的范围内；以及
    所述式I-C化合物的含量为Z％，Z在0.12至3.0的范围内。
  2. 根据权利要求1所述的电解液，其中：
    所述X在0.5至4.2的范围内；
    所述Y在0.5至4.2的范围内；以及
    所述Z在0.5至3.0的范围内。
  3. 根据权利要求1所述的电解液，其中Z/X在0.1至3的范围内。
  4. 根据权利要求3所述的电解液，其中Z/X在0.6至2.5的范围内。
  5. 根据权利要求1所述的电解液，其中所述式Ⅰ-A化合物包括以下化合物中的至少一种：




  6. 根据权利要求1所述的电解液，其中所述式Ⅰ-B化合物包括以下化合物中的至少一种：
  7. 根据权利要求1所述的电解液，其中所述式Ⅰ-C化合物包括以下化合物中的至少一种：
  8. 根据权利要求1所述的电解液，其中Y/X在0.12至5的范围内。
  9. 根据权利要求1所述的电解液，其中所述电解液还包括含硫氧双键的化合物，并且基于所述电解液的质量，所述含硫氧双键的化合物的含量为 0.01％至10％。
  10. 根据权利要求9所述的电解液，其中所述含硫氧双键的化合物包括具有式II的化合物：
    其中：
    R21和R22各自独立地选自经取代或未经取代的C1-C5烷基、经取代或未经取代的C2-C10烯基、经取代或未经取代的C2-C10炔基、经取代或未经取代的C3-C10脂环基、经取代或未经取代的C6-C10芳基或经取代或未经取代的含有C1-C5的杂原子官能团，所述杂原子官能团中的杂原子选自O或S中的至少一种；
    R21和R22任选地连接在一起形成环；并且
    当经取代时，取代基各自独立地选自卤素。
  11. 根据权利要求9所述的电解液，其中所述含硫氧双键的化合物包括以下化合物中的至少一种：
  12. 根据权利要求1所述的电解液，其中所述电解液还包括式Ⅲ化合物：
    其中：
    R31选自经取代或未经取代的C1-C6亚烷基或经取代或未经取代的C2-C6亚烯基；
    当经取代时，取代基各自独立地选自卤素、C1-C6烷基或C2-C6烯基；并且
    基于所述电解液的质量，所述式Ⅲ化合物的含量为0.01％至15％。
  13. 根据权利要求12所述的电解液，其中所述式Ⅲ化合物包括以下化合物中的至少一种：
  14. 根据权利要求1所述的电解液，其中所述电解液还包括化合物IV，所述化合物IV包括以下化合物中的至少一种：
  15. 根据权利要求14所述的电解液，其中基于所述电解液的质量，所述化合物IV的含量为0.01％至2％。
  16. 根据权利要求1所述的电解液，其中所述电解液还包括含硼锂盐， 并且基于所述电解液的质量，所述含硼锂盐的含量为0.01％至1％。
  17. 根据权利要求16所述的电解液，其中所述含硼锂盐包括四氟硼酸锂、二草酸硼酸锂或二氟草酸硼酸锂中的至少一种。
  18. 根据权利要求16所述的电解液，其中基于所述电解液的质量，所述含硼锂盐的含量为M％，并且M/X不大于1。
  19. 一种电化学装置，其包括根据权利要求1至18中任一项所述的电解液。
  20. 一种电子装置，其包括根据权利要求19所述的电化学装置。
PCT/CN2023/076752 2023-02-17 2023-02-17 电解液和电化学装置 Ceased WO2024168804A1 (zh)

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Publication number Priority date Publication date Assignee Title
CN109786824A (zh) * 2019-01-25 2019-05-21 宁德新能源科技有限公司 电解液和使用其的电化学装置
CN114094192A (zh) * 2021-12-03 2022-02-25 宁德新能源科技有限公司 一种电解液、包含该电解液的电化学装置及电子装置
WO2022087830A1 (zh) * 2020-10-27 2022-05-05 宁德新能源科技有限公司 电解液及包括其的电化学装置和电子装置

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Publication number Priority date Publication date Assignee Title
CN109786824A (zh) * 2019-01-25 2019-05-21 宁德新能源科技有限公司 电解液和使用其的电化学装置
WO2022087830A1 (zh) * 2020-10-27 2022-05-05 宁德新能源科技有限公司 电解液及包括其的电化学装置和电子装置
CN114094192A (zh) * 2021-12-03 2022-02-25 宁德新能源科技有限公司 一种电解液、包含该电解液的电化学装置及电子装置

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