WO2023130249A1 - 电解液及使用其的二次电池、电池模块、电池包以及用电装置 - Google Patents

电解液及使用其的二次电池、电池模块、电池包以及用电装置 Download PDF

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WO2023130249A1
WO2023130249A1 PCT/CN2022/070280 CN2022070280W WO2023130249A1 WO 2023130249 A1 WO2023130249 A1 WO 2023130249A1 CN 2022070280 W CN2022070280 W CN 2022070280W WO 2023130249 A1 WO2023130249 A1 WO 2023130249A1
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electrolyte
hydrogen
unsubstituted
carbonate
halogen
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PCT/CN2022/070280
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English (en)
French (fr)
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沙莹
谢岚
林真
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宁德时代新能源科技股份有限公司
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Priority to EP22899605.4A priority Critical patent/EP4243151A4/en
Priority to CN202280019500.2A priority patent/CN117044005A/zh
Priority to PCT/CN2022/070280 priority patent/WO2023130249A1/zh
Priority to US18/324,397 priority patent/US20230299357A1/en
Publication of WO2023130249A1 publication Critical patent/WO2023130249A1/zh

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
    • H01M10/0564—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of organic materials only
    • H01M10/0566—Liquid materials
    • H01M10/0567—Liquid materials characterised by the additives
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07D—HETEROCYCLIC COMPOUNDS
    • C07D207/00—Heterocyclic compounds containing five-membered rings not condensed with other rings, with one nitrogen atom as the only ring hetero atom
    • C07D207/02—Heterocyclic compounds containing five-membered rings not condensed with other rings, with one nitrogen atom as the only ring hetero atom with only hydrogen or carbon atoms directly attached to the ring nitrogen atom
    • C07D207/30—Heterocyclic compounds containing five-membered rings not condensed with other rings, with one nitrogen atom as the only ring hetero atom with only hydrogen or carbon atoms directly attached to the ring nitrogen atom having two double bonds between ring members or between ring members and non-ring members
    • C07D207/34—Heterocyclic compounds containing five-membered rings not condensed with other rings, with one nitrogen atom as the only ring hetero atom with only hydrogen or carbon atoms directly attached to the ring nitrogen atom having two double bonds between ring members or between ring members and non-ring members with hetero atoms or with carbon atoms having three bonds to hetero atoms with at the most one bond to halogen, e.g. ester or nitrile radicals, directly attached to ring carbon atoms
    • C07D207/36—Oxygen or sulfur atoms
    • C07D207/40—2,5-Pyrrolidine-diones
    • C07D207/404—2,5-Pyrrolidine-diones with only hydrogen atoms or radicals containing only hydrogen and carbon atoms directly attached to other ring carbon atoms, e.g. succinimide
    • C07D207/408—Radicals containing only hydrogen and carbon atoms attached to ring carbon atoms
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07D—HETEROCYCLIC COMPOUNDS
    • C07D307/00—Heterocyclic compounds containing five-membered rings having one oxygen atom as the only ring hetero atom
    • C07D307/02—Heterocyclic compounds containing five-membered rings having one oxygen atom as the only ring hetero atom not condensed with other rings
    • C07D307/34—Heterocyclic compounds containing five-membered rings having one oxygen atom as the only ring hetero atom not condensed with other rings having two or three double bonds between ring members or between ring members and non-ring members
    • C07D307/56—Heterocyclic compounds containing five-membered rings having one oxygen atom as the only ring hetero atom not condensed with other rings having two or three double bonds between ring members or between ring members and non-ring members with hetero atoms or with carbon atoms having three bonds to hetero atoms with at the most one bond to halogen, e.g. ester or nitrile radicals, directly attached to ring carbon atoms
    • C07D307/60—Two oxygen atoms, e.g. succinic anhydride
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07D—HETEROCYCLIC COMPOUNDS
    • C07D307/00—Heterocyclic compounds containing five-membered rings having one oxygen atom as the only ring hetero atom
    • C07D307/02—Heterocyclic compounds containing five-membered rings having one oxygen atom as the only ring hetero atom not condensed with other rings
    • C07D307/34—Heterocyclic compounds containing five-membered rings having one oxygen atom as the only ring hetero atom not condensed with other rings having two or three double bonds between ring members or between ring members and non-ring members
    • C07D307/56—Heterocyclic compounds containing five-membered rings having one oxygen atom as the only ring hetero atom not condensed with other rings having two or three double bonds between ring members or between ring members and non-ring members with hetero atoms or with carbon atoms having three bonds to hetero atoms with at the most one bond to halogen, e.g. ester or nitrile radicals, directly attached to ring carbon atoms
    • C07D307/64—Sulfur atoms
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07D—HETEROCYCLIC COMPOUNDS
    • C07D307/00—Heterocyclic compounds containing five-membered rings having one oxygen atom as the only ring hetero atom
    • C07D307/02—Heterocyclic compounds containing five-membered rings having one oxygen atom as the only ring hetero atom not condensed with other rings
    • C07D307/34—Heterocyclic compounds containing five-membered rings having one oxygen atom as the only ring hetero atom not condensed with other rings having two or three double bonds between ring members or between ring members and non-ring members
    • C07D307/56—Heterocyclic compounds containing five-membered rings having one oxygen atom as the only ring hetero atom not condensed with other rings having two or three double bonds between ring members or between ring members and non-ring members with hetero atoms or with carbon atoms having three bonds to hetero atoms with at the most one bond to halogen, e.g. ester or nitrile radicals, directly attached to ring carbon atoms
    • C07D307/66—Nitrogen atoms
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07D—HETEROCYCLIC COMPOUNDS
    • C07D333/00—Heterocyclic compounds containing five-membered rings having one sulfur atom as the only ring hetero atom
    • C07D333/02—Heterocyclic compounds containing five-membered rings having one sulfur atom as the only ring hetero atom not condensed with other rings
    • C07D333/04—Heterocyclic compounds containing five-membered rings having one sulfur atom as the only ring hetero atom not condensed with other rings not substituted on the ring sulphur atom
    • C07D333/26—Heterocyclic compounds containing five-membered rings having one sulfur atom as the only ring hetero atom not condensed with other rings not substituted on the ring sulphur atom with hetero atoms or with carbon atoms having three bonds to hetero atoms with at the most one bond to halogen, e.g. ester or nitrile radicals, directly attached to ring carbon atoms
    • C07D333/30—Hetero atoms other than halogen
    • C07D333/32—Oxygen atoms
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07F—ACYCLIC, CARBOCYCLIC OR HETEROCYCLIC COMPOUNDS CONTAINING ELEMENTS OTHER THAN CARBON, HYDROGEN, HALOGEN, OXYGEN, NITROGEN, SULFUR, SELENIUM OR TELLURIUM
    • C07F7/00—Compounds containing elements of Groups 4 or 14 of the Periodic Table
    • C07F7/02—Silicon compounds
    • C07F7/08—Compounds having one or more C—Si linkages
    • C07F7/0803—Compounds with Si-C or Si-Si linkages
    • C07F7/081—Compounds with Si-C or Si-Si linkages comprising at least one atom selected from the elements N, O, halogen, S, Se or Te
    • C07F7/0812—Compounds with Si-C or Si-Si linkages comprising at least one atom selected from the elements N, O, halogen, S, Se or Te comprising a heterocyclic ring
    • C07F7/0814—Compounds with Si-C or Si-Si linkages comprising at least one atom selected from the elements N, O, halogen, S, Se or Te comprising a heterocyclic ring said ring is substituted at a C ring atom by Si
    • 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
    • H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
    • H01M10/0564—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of organic materials only
    • H01M10/0566—Liquid materials
    • H01M10/0569—Liquid materials characterised by the solvents
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M2300/00—Electrolytes
    • H01M2300/0017—Non-aqueous electrolytes
    • H01M2300/0025—Organic electrolyte
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M2300/00—Electrolytes
    • H01M2300/0017—Non-aqueous electrolytes
    • H01M2300/0025—Organic electrolyte
    • H01M2300/0028—Organic electrolyte characterised by the solvent
    • H01M2300/0034—Fluorinated solvents
    • 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
    • H01M2300/0028—Organic electrolyte characterised by the solvent
    • H01M2300/0037—Mixture of solvents
    • 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 technical field of secondary batteries, in particular to an electrolyte solution for a secondary battery, a secondary battery using the same, a battery module, a battery pack and an electrical device.
  • a secondary battery is generally composed of a positive electrode, a negative electrode, an electrolyte, and the like.
  • charge transfer is usually achieved through the deintercalation of lithium ions in the positive and negative electrodes and the transfer of electrolytes in the electrolyte, thereby performing mutual conversion of chemical energy and electrical energy.
  • the present application is made in view of the above-mentioned technical problems, and its purpose is to provide a secondary battery electrolyte that prevents the positive electrode material from being corroded and transition metals from being leached, and a secondary battery using it, so that the secondary battery can be improved.
  • Excellent cycle life and storage performance, especially for secondary batteries operating at high voltage ( ⁇ 4.35V), can also improve their cycle life and storage performance.
  • the first aspect of the present application provides a kind of electrolytic solution, and it comprises organic solvent and the compound (A) represented by one or more following general formula (I) or general formula (II),
  • X is selected from any element in O, S, N,
  • R includes cyano or isocyanate, trimethylsilyl, straight-chain or branched-chain alkyl with 2-4 carbon atoms, carbon atoms in which some or all hydrogens are replaced by halogens
  • R includes a hydrogen atom, a cyano group or an isocyanate group, a trimethylsilyl group, a straight-chain or branched-chain alkyl group with 1-4 carbon atoms, and some hydrogen Or a straight-chain alkyl group with 1-4 carbon atoms in which all hydrogens are replaced by halogens, phenyl or benzyl with partial or all hydrogens substituted
  • the content of the compound (A) in the electrolyte is 0.01wt%-5wt%
  • the content of ethylene carbonate in the organic solvent is less than or equal to 3wt%.
  • the compound (A) can capture the transition metal ions dissolved in the electrolyte, and can form a film on the positive electrode to protect the positive electrode material. Further, by controlling the content of ethylene carbonate, the penetration and erosion of the positive electrode material by the solvent can be reduced. Reduce the dissolution of transition metals in the positive electrode material, thereby improving the cycle life and storage performance of the secondary battery, especially when the secondary battery is working at a high voltage ( ⁇ 4.35V), it can still maintain its cycle life and storage performance. performance.
  • R when X is O in the general formula (I) or general formula (II), R includes cyano or isocyanate, trimethylsilyl, and carbon atoms of 2-4 Straight-chain alkyl, straight-chain alkyl with 1-4 carbon atoms in which part or all of hydrogen is substituted by halogen, phenyl or benzyl in which part or all of hydrogen is substituted or unsubstituted by halogen, part or all of hydrogen One or more of sulfonyl or sulfonic acid groups substituted or unsubstituted by halogen; when X is S or N, R includes cyano or isocyanate, trimethylsilyl, hydrogen atom, carbon number 2-4 straight-chain alkyl, straight-chain alkyl with 1-4 carbon atoms in which part or all of hydrogen is replaced by halogen, phenyl or benzyl in which part or all of hydrogen is substituted or unsubstituted by halogen, One or more of the
  • R when X is O, R includes a cyano group or an isocyanate group, a trimethylsilyl group, a straight-chain alkyl group with 2-3 carbon atoms, a carbon atom number in which some or all hydrogens are replaced by halogens One of 1-3 straight-chain alkyl, phenyl or benzyl with part or all of hydrogen substituted or unsubstituted by halogen, sulfonyl or sulfonyl with part or all of hydrogen substituted or unsubstituted by halogen or several; when X is S or N, R includes cyano group or isocyanate group, trimethylsilyl group, hydrogen atom, straight-chain alkyl group with 2-3 carbon atoms, part of hydrogen or all hydrogen replaced by halogen Substituted straight-chain alkyl with 1-3 carbon atoms, phenyl or benzyl with some or all hydrogens substituted or unsubstituted by halogen, sulf
  • the protective effect of the compound (A) on the positive electrode material can be further improved, and the cycle life and storage performance of the secondary battery can be further improved.
  • the compound (A) is one or more selected from the following compounds (A1)-(A12):
  • the compound (A) is one or more selected from the above compounds (A1), (A2), (A4)-(A6), (A8), (A9), (A11) .
  • the ability of the compound (A) to capture transition metal ions can be further improved, and the film-forming ability of the compound (A) on the surface of the positive electrode can be improved, thereby further improving the protective effect of the compound (A) on the positive electrode material, and can further improve Cycle life and storage performance of secondary batteries.
  • the content of the compound (A) in the electrolyte is 1wt%-5wt%, optionally 2wt%-3wt%.
  • the organic solvent does not contain ethylene carbonate (EC).
  • EC ethylene carbonate
  • the organic solvent contains one or two or more selected from chain carbonates, cyclic carbonates other than ethylene carbonate, carboxylates, and ether solvents. Therefore, it is possible to ensure that the electrolyte has sufficient ion conductivity even when the content of ethylene carbonate is reduced, so that the cycle life and storage performance of the battery can be reliably improved.
  • the content of the chain carbonate in the electrolyte is 40wt%-90wt%. In this way, the protective effect of the electrolyte on the positive electrode material and the ion conductivity of the electrolyte can be taken into account, so that the cycle life and storage performance of the battery can be reliably improved.
  • the above-mentioned chain carbonate is selected from dimethyl carbonate, diethyl carbonate, dipropyl carbonate, ethyl methyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, trifluoroethyl methyl Carbonate
  • the cyclic carbonate other than the above-mentioned ethylene carbonate is selected from fluoroethylene carbonate
  • the above-mentioned carboxylate is selected from ethyl acetate, methyl acetate, propyl acetate
  • the above-mentioned ether solvent is selected from 1,1, 2,2-Tetrafluoroethyl-2,2,2-trifluoroethyl ether, desflurane, 2,2,2-trifluoroethyl-30,30,30,20,20-pentafluoropropyl ether.
  • the second aspect of the present application provides a secondary battery, which includes the electrolyte solution of the first aspect of the present application.
  • a third aspect of the present application provides a battery module including the secondary battery of the second aspect of the present application.
  • a fourth aspect of the present application provides a battery pack, which includes the battery module of the third aspect of the present application.
  • a fifth aspect of the present application provides an electric device, which includes at least one of the secondary batteries selected from the second aspect of the present application, the battery module of the third aspect of the present application, or the battery pack of the fourth aspect of the present application A sort of.
  • FIG. 1 is a schematic diagram of a secondary battery according to one embodiment of the present application.
  • FIG. 2 is an exploded view of the secondary battery according to one embodiment of the present application shown in FIG. 1 .
  • Fig. 3 is a schematic diagram of a battery module according to an embodiment of the present application.
  • Fig. 4 is a schematic diagram of a battery pack according to an embodiment of the present application.
  • Fig. 5 is an exploded view of the battery pack according to one embodiment of the present application shown in Fig. 4 .
  • Fig. 6 is a schematic diagram of an electrical device according to an embodiment of the present application.
  • ranges disclosed herein are defined in terms of lower and upper limits, and a given range is defined by selecting a lower limit and an upper limit that define the boundaries of the particular range. Ranges defined in this manner may be inclusive or exclusive and may be combined arbitrarily, ie any lower limit may be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a particular parameter, it is understood that ranges of 60-110 and 80-120 are contemplated. Additionally, if the minimum range values 1 and 2 are listed, and if the maximum range values 3, 4, and 5 are listed, the following ranges are all expected: 1-3, 1-4, 1-5, 2- 3, 2-4 and 2-5.
  • the numerical range "a-b” represents an abbreviated representation of any combination of real numbers between a and b, where a and b are both real numbers.
  • the numerical range "0-5" indicates that all real numbers between "0-5" have been listed in this article, and "0-5" is only an abbreviated representation of the combination of these values.
  • a certain parameter is an integer ⁇ 2
  • the method includes steps (a) and (b), which means that the method may include steps (a) and (b) performed in sequence, and may also include steps (b) and (a) performed in sequence.
  • steps (c) means that step (c) may be added to the method in any order, for example, the method may include steps (a), (b) and (c) , may also include steps (a), (c) and (b), may also include steps (c), (a) and (b) and so on.
  • the “comprising” and “comprising” mentioned in this application mean open or closed.
  • the “comprising” and “comprising” may mean that other components not listed may be included or included, or only listed components may be included or included.
  • the term "or” is inclusive unless otherwise stated.
  • the phrase "A or B” means “A, B, or both A and B.” More specifically, the condition "A or B” is satisfied by either of the following: A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists) ; or both A and B are true (or exist).
  • impurities such as hydrofluoric acid may be produced due to the reaction of lithium salt in the electrolyte with a very small amount of water, etc.
  • These impurity acids may corrode the positive electrode material and dissolve active substances such as transition metals in the positive electrode material, which will lead to The collapse of the positive electrode material structure directly leads to problems such as reduced battery storage performance and reduced battery cycle life.
  • redox reactions are more likely to occur on the surface of the positive electrode material, and the transition metal ions in the positive electrode material are accelerated to dissolve under the action of the electrolyte, which seriously restricts the electrochemical performance of the positive electrode material. It will also lead to battery safety issues such as explosion.
  • the inventors of the present application conducted research from the perspective of the electrolyte.
  • the additive can form a film on the surface of the electrode to protect the positive electrode material.
  • the composition of the electrolyte Reduce the content of components that will erode the positive electrode material in the electrolyte, thereby synergistically protecting the positive electrode material from being eroded and dissolved by the electrolyte, improving the cycle life and storage performance of the battery, especially when the battery is working at high voltage, it can also protect the positive electrode materials, stabilize the storage performance of the secondary battery, and improve the cycle life of the secondary battery.
  • an electrolyte solution which includes an organic solvent, and one or more than two compounds (A) represented by the following general formula (I) or general formula (II), the above-mentioned compound ( A)
  • the content in the electrolyte is 0.01wt%-5wt%, and the content of ethylene carbonate in the organic solvent is less than or equal to 3wt%.
  • X is selected from any element in O, S, N.
  • R includes cyano or isocyanate, trimethyl Silicon group, straight-chain or branched-chain alkyl group with 2-4 carbon atoms, straight-chain alkyl group with 1-4 carbon atoms replaced by part or all of hydrogen by halogen, part or all of hydrogen by halogen Substituted or unsubstituted phenyl or benzyl, one or more of sulfonyl or sulfonic acid groups substituted or unsubstituted by halogens for some or all hydrogens; when X is S or N, R includes hydrogen atoms, Cyano or isocyanate, trimethylsilyl, straight-chain or branched-chain alkyl with 1-4 carbon atoms, straight-chain or branched-chain alkyl with 1-4 carbon atoms in which some or all of the hydrogen is replaced by halogen
  • One or more of the hydrogen is replaced by halogen
  • the present application contains above-mentioned specific compound (A) with above-mentioned specific range in electrolytic solution, and reduces the content of ethylene carbonate commonly used in organic solvent, thus not only can reduce electrolytic solution to anode material Corrosion force can also form a protective film on the surface of the positive electrode material, so that the positive electrode material can be reliably protected from the erosion and dissolution of the electrolyte, and the cycle life and storage performance of the secondary battery can be improved.
  • the above-mentioned specific compound (A) has a complexing ability to transition metals, so it can capture transition metal ions dissolved in the electrolyte to prevent the transition metals from being dissolved by the electrolyte.
  • the adsorption effect can form a film on the surface of the positive electrode material to protect the positive electrode material from the erosion of the electrolyte.
  • R when X is O, R includes cyano group or isocyanate group, trimethylsilyl group, carbon number of 2-4 Straight-chain alkyl, straight-chain alkyl with 1-4 carbon atoms in which part or all of hydrogen is substituted by halogen, phenyl or benzyl in which part or all of hydrogen is substituted or unsubstituted by halogen, part or all of hydrogen One or more of sulfonyl or sulfonic acid groups substituted or unsubstituted by halogen; when X is S or N, R includes cyano or isocyanate, trimethylsilyl, hydrogen atom, carbon atom Straight-chain alkyl with 2-4 hydrogens, straight-chain alkyl with 1-4 carbon atoms with some or all hydrogens replaced by halogens, phenyl or benzyl with some or all hydrogens substituted or unsubstituted by halogens
  • R when X is O, R includes a cyano group or an isocyanate group, a trimethylsilyl group, a straight-chain alkyl group with 2-3 carbon atoms, a carbon atom in which some or all hydrogens are replaced by halogens One of 1-3 straight-chain alkyl groups, phenyl or benzyl with some or all of the hydrogens substituted or unsubstituted by halogens, sulfonyl or sulfonic acid groups with some or all of the hydrogens substituted or unsubstituted by halogens One or several kinds; when X is S or N, R includes cyano or isocyanate, trimethylsilyl, hydrogen atom, straight-chain alkyl group with 2-3 carbon atoms, partial hydrogen or all hydrogen A linear alkyl group with 1-3 carbon atoms substituted by halogen, a phenyl or benzyl group in which some or all of the hydrogen is substituted or unsubstituted by hal
  • the above compound (A) is one or more selected from the following compounds (A1)-(A12).
  • compound (A) is one or more selected from compounds (A1), (A2), (A4)-(A6), (A8), (A9) and (A11).
  • the compound (A) can efficiently capture the transition metal ions dissolved in the positive electrode material, and easily form a film on the surface of the positive electrode material, so that the positive electrode material can be well protected from being corroded by the electrolyte.
  • the content of the compound (A) in the electrolyte is 1wt%-5wt%, optionally 2wt%-3wt%. If the content of the compound (A) in the electrolyte is too small, a good interfacial film cannot be formed on the surface of the positive electrode, and it is difficult to prevent the decomposition of the solvent and the dissolution of the transition metal under high voltage. If the content of compound (A) in the electrolyte is too much, the viscosity of the electrolyte will be increased, the resistance to lithium ion migration will be increased, and the interfacial film formed on the surface of the positive electrode will be too thick, resulting in the membrane resistance and charge transfer of the secondary battery. Impedance is too high.
  • the organic solvent is substantially free of ethylene carbonate.
  • the influence of ethylene carbonate on the positive electrode material can be completely eliminated, and the transition metals can be prevented from being eroded and eluted.
  • the organic solvent contains one or two or more selected from chain carbonates, cyclic carbonates other than ethylene carbonate, carboxylates, and ether solvents. Therefore, it can replace the function of ethylene carbonate commonly used in the prior art, thereby reducing the erosion of the electrolyte on the positive electrode material, while ensuring the conductivity of the electrolyte and ensuring the normal charging and discharging of the secondary battery. As a result, the cycle life and storage performance of the battery can be reliably improved.
  • the content of the chain carbonate in the electrolyte is 40wt%-90wt%. In this way, the protective effect of the electrolyte on the positive electrode material and the ion conductivity of the electrolyte can be taken into account, so that the cycle life and storage performance of the battery can be reliably improved.
  • the above-mentioned chain carbonate is selected from dimethyl carbonate, diethyl carbonate, dipropyl carbonate, ethyl methyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, trifluoroethyl methyl carbonate Carbonate;
  • the cyclic carbonate other than ethylene carbonate is selected from fluoroethylene carbonate;
  • the carboxylate is selected from ethyl acetate, methyl acetate, propyl acetate;
  • the ether solvent is selected from 1,1, 2,2-Tetrafluoroethyl-2,2,2-trifluoroethyl ether, desflurane, 2,2,2-trifluoroethyl-30,30,30,20,20-pentafluoropropyl ether.
  • the organic solvent content in the electrolyte is 60wt%-98wt%.
  • the organic solvent may further include any one selected from 1,4-butyrolactone, sulfolane, dimethylsulfone, methylethylsulfone, and diethylsulfone.
  • the electrolyte solution further includes an electrolyte salt, wherein the electrolyte salt can be selected from lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bisfluorosulfonyl imide, bistrifluoromethane At least one of lithium sulfonyl imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorooxalate borate, lithium difluorooxalate borate, lithium difluorodifluorooxalate phosphate, and lithium tetrafluorooxalate phosphate.
  • the electrolyte salt can be selected from lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bisfluorosulfonyl imide, bistrifluoromethane At least one
  • the electrolyte may optionally include other additives such as negative electrode film-forming additives, and may also include additives that can improve certain performances of the battery, such as additives that improve battery overcharge performance, improve battery high-temperature or low-temperature performance additives, etc.
  • a secondary battery is provided.
  • a secondary battery typically includes a positive pole piece, a negative pole piece, an electrolyte, and a separator.
  • active ions are intercalated and extracted back and forth between the positive electrode and the negative electrode.
  • the electrolyte plays the role of conducting ions between the positive pole piece and the negative pole piece.
  • the separator is arranged between the positive pole piece and the negative pole piece, which mainly plays the role of preventing the short circuit of the positive and negative poles, and at the same time allows ions to pass through.
  • the electrolytic solution included in the secondary battery of this embodiment is the electrolytic solution provided in the above-mentioned embodiment.
  • the positive electrode sheet includes a positive electrode collector and a positive electrode film layer arranged on at least one surface of the positive electrode collector, and the positive electrode film layer includes a positive electrode active material.
  • the positive electrode current collector has two opposing surfaces in its own thickness direction, and the positive electrode film layer is disposed on any one or both of the two opposing surfaces of the positive electrode current collector.
  • the positive electrode current collector can be a metal foil or a composite current collector.
  • aluminum foil can be used as the metal foil.
  • the composite current collector may include a polymer material base and a metal layer formed on at least one surface of the polymer material base.
  • the composite current collector can be formed by forming metal materials (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as polypropylene (PP), polyethylene terephthalic acid It is formed on substrates such as ethylene glycol ester (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).
  • PP polypropylene
  • PET polyethylene glycol ester
  • PBT polybutylene terephthalate
  • PS polystyrene
  • PE polyethylene
  • the positive electrode active material may be a positive electrode active material known in the art for batteries.
  • the positive active material may include at least one of the following materials: olivine-structured lithium-containing phosphate, lithium transition metal oxide, and their respective modified compounds.
  • the present application is not limited to these materials, and other conventional materials that can be used as positive electrode active materials of batteries can also be used. These positive electrode active materials may be used alone or in combination of two or more.
  • lithium transition metal oxides may include, but are not limited to, lithium cobalt oxides (such as LiCoO 2 ), lithium nickel oxides (such as LiNiO 2 ), lithium manganese oxides (such as LiMnO 2 , LiMn 2 O 4 ), lithium Nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide (such as LiNi 1/3 Co 1/3 Mn 1/3 O 2 (also referred to as NCM 333 ), LiNi 0.5 Co 0.2 Mn 0.3 O 2 (also abbreviated as NCM 523 ), LiNi 0.5 Co 0.25 Mn 0.25 O 2 (also abbreviated as NCM 211 ), LiNi 0.6 Co 0.2 Mn 0.2 O 2 (also abbreviated as NCM 622 ), LiNi At least one of 0.8 Co 0.1 Mn 0.1 O 2 (also referred to as NCM 811 ), lithium nickel cobalt aluminum oxide (such as LiNi
  • the olivine structure contains Examples of lithium phosphates may include, but are not limited to, lithium iron phosphate (such as LiFePO 4 (also may be abbreviated as LFP)), composite materials of lithium iron phosphate and carbon, lithium manganese phosphate (such as LiMnPO 4 ), lithium manganese phosphate and carbon At least one of a composite material, lithium manganese iron phosphate, and a composite material of lithium manganese iron phosphate and carbon.
  • lithium iron phosphate such as LiFePO 4 (also may be abbreviated as LFP)
  • composite materials of lithium iron phosphate and carbon such as LiMnPO 4
  • LiMnPO 4 lithium manganese phosphate and carbon
  • the positive electrode film layer may further optionally include a binder.
  • the binder may include polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene At least one of ethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer and fluorine-containing acrylate resin.
  • the positive electrode film layer may also optionally include a conductive agent.
  • the conductive agent may include at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.
  • the positive electrode sheet can be prepared in the following manner: the above-mentioned components used to prepare the positive electrode sheet, such as positive electrode active material, conductive agent, binder and any other components, are dispersed in a solvent (such as N -methylpyrrolidone) to form a positive electrode slurry; the positive electrode slurry is coated on the positive electrode current collector, and after drying, cold pressing and other processes, the positive electrode sheet can be obtained.
  • a solvent such as N -methylpyrrolidone
  • the negative electrode sheet includes a negative electrode current collector and a negative electrode film layer arranged on at least one surface of the negative electrode current collector, and the negative electrode film layer includes a negative electrode active material.
  • the negative electrode current collector has two opposing surfaces in its own thickness direction, and the negative electrode film layer is disposed on any one or both of the two opposing surfaces of the negative electrode current collector.
  • the negative electrode current collector can use a metal foil or a composite current collector.
  • copper foil can be used as the metal foil.
  • the composite current collector may include a base layer of polymer material and a metal layer formed on at least one surface of the base material of polymer material.
  • Composite current collectors can be formed by metal materials (copper, copper alloys, nickel, nickel alloys, titanium, titanium alloys, silver and silver alloys, etc.) on polymer material substrates (such as polypropylene (PP), polyethylene terephthalic acid It is formed on substrates such as ethylene glycol ester (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).
  • the negative electrode active material can be a negative electrode active material known in the art for batteries.
  • the negative electrode active material may include at least one of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based material, tin-based material, lithium titanate, and the like.
  • the silicon-based material can be selected from at least one of elemental silicon, silicon-oxygen compounds, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys.
  • the tin-based material may be selected from at least one of simple tin, tin oxide compounds and tin alloys.
  • the present application is not limited to these materials, and other conventional materials that can be used as negative electrode active materials of batteries can also be used. These negative electrode active materials may be used alone or in combination of two or more.
  • the negative electrode film layer may further optionally include a binder.
  • the binder can be selected from styrene-butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), poly At least one of methacrylic acid (PMAA) and carboxymethyl chitosan (CMCS).
  • the negative electrode film layer may also optionally include a conductive agent.
  • the conductive agent can be selected from at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene and carbon nanofibers.
  • the negative electrode film layer may optionally include other additives, such as thickeners (such as sodium carboxymethylcellulose (CMC-Na)) and the like.
  • thickeners such as sodium carboxymethylcellulose (CMC-Na)
  • CMC-Na sodium carboxymethylcellulose
  • the negative electrode sheet can be prepared in the following manner: the above-mentioned components used to prepare the negative electrode sheet, such as negative electrode active material, conductive agent, binder and any other components, are dispersed in a solvent (such as deionized water) to form a negative electrode slurry; the negative electrode slurry is coated on the negative electrode current collector, and after drying, cold pressing and other processes, the negative electrode sheet can be obtained.
  • a solvent such as deionized water
  • a separator is further included in the secondary battery.
  • the present application has no particular limitation on the type of the isolation membrane, and any known porous structure isolation membrane with good chemical stability and mechanical stability can be selected.
  • the material of the isolation film can be selected from at least one of glass fiber, non-woven fabric, polyethylene, polypropylene and polyvinylidene fluoride.
  • the separator can be a single-layer film or a multi-layer composite film, without any particular limitation. When the separator is a multilayer composite film, the materials of each layer may be the same or different, and there is no particular limitation.
  • the positive pole piece, the negative pole piece and the separator can be made into an electrode assembly through a winding process or a lamination process.
  • the secondary battery may include an outer package.
  • the outer package can be used to package the above-mentioned electrode assembly and electrolyte.
  • the outer package of the secondary battery can be a hard case, such as a hard plastic case, an aluminum case, a steel case, and the like.
  • the outer packaging of the secondary battery may also be a soft bag, such as a bag-type soft bag.
  • the material of the soft case may be plastic, and examples of the plastic include polypropylene, polybutylene terephthalate, polybutylene succinate, and the like.
  • FIG. 1 shows a square-shaped secondary battery 5 as an example.
  • the outer package may include a housing 51 and a cover 53 .
  • the housing 51 may include a bottom plate and a side plate connected to the bottom plate, and the bottom plate and the side plates enclose to form an accommodating cavity.
  • the housing 51 has an opening communicating with the accommodating cavity, and the cover plate 53 can cover the opening to close the accommodating cavity.
  • the positive pole piece, the negative pole piece and the separator can be formed into an electrode assembly 52 through a winding process or a lamination process.
  • the electrode assembly 52 is packaged in the accommodating chamber. Electrolyte is infiltrated in the electrode assembly 52 .
  • the number of electrode assemblies 52 contained in the secondary battery 5 can be one or more, and those skilled in the art can select according to specific actual needs.
  • the secondary battery can be assembled into a battery module, and the number of secondary batteries contained in the battery module can be one or more, and the specific number can be selected by those skilled in the art according to the application and capacity of the battery module.
  • FIG. 3 is a battery module 4 as an example.
  • a plurality of secondary batteries 5 may be arranged in sequence along the length direction of the battery module 4 .
  • the plurality of secondary batteries 5 may be fixed by fasteners.
  • the battery module 4 may also include a case having a housing space in which a plurality of secondary batteries 5 are accommodated.
  • the above-mentioned battery modules can also be assembled into a battery pack, and the number of battery modules contained in the battery pack can be one or more, and the specific number can be selected by those skilled in the art according to the application and capacity of the battery pack.
  • the battery pack 1 may include a battery box and a plurality of battery modules 4 disposed in the battery box.
  • the battery box includes an upper box body 2 and a lower box body 3 , the upper box body 2 can cover the lower box body 3 and form a closed space for accommodating the battery module 4 .
  • Multiple battery modules 4 can be arranged in the battery box in any manner.
  • the present application also provides an electric device, which includes at least one of the secondary battery, battery module, or battery pack provided in the present application.
  • the secondary battery, battery module, or battery pack can be used as a power source of the electric device, and can also be used as an energy storage unit of the electric device.
  • the electric devices may include mobile devices (such as mobile phones, notebook computers, etc.), electric vehicles (such as pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, etc.) , electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc., but not limited thereto.
  • a secondary battery, a battery module or a battery pack can be selected according to its use requirements.
  • FIG. 6 is an example of an electrical device.
  • the electric device is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle.
  • a battery pack or a battery module may be used.
  • a device may be a cell phone, tablet, laptop, or the like.
  • the device is generally required to be light and thin, and a secondary battery can be used as a power source.
  • the ethyl methyl carbonate (EMC) of the chain carbonate is used as the main solvent, and the ethyl methyl carbonate (EMC) and each auxiliary solvent are used as the main solvent according to the following table 1
  • the indicated weight ratio of the auxiliary solvent to the main solvent (auxiliary solvent: main solvent (EMC)) was mixed to obtain a mixed solvent.
  • the weight percentage (wt %) indicating the content of the compound (A) in Table 1 is the weight percentage (wt %) relative to the electrolyte solution.
  • the secondary batteries of Examples 1-19 and Comparative Examples 1-8 were prepared according to the following methods.
  • Capacity retention (%) of the secondary battery after high-temperature cycles [discharge capacity at the 100th cycle/discharge capacity at the first cycle] ⁇ 100%.
  • the volume of the secondary battery is taken as the initial volume of the secondary battery (that is, the volume of the secondary battery before high-temperature storage), and then the surface of the secondary battery is dried and stored at 60°C for 30 days.
  • the volume of the secondary battery was taken as the volume of the secondary battery after high-temperature storage, and the volume expansion rate (%) of the secondary battery after high-temperature storage was calculated according to the following formula, and the results are shown in Table 2.
  • Volume expansion rate (%) of the secondary battery after high-temperature storage [(volume of the secondary battery after high-temperature storage-initial volume of the secondary battery)/initial volume of the secondary battery] ⁇ 100%.
  • Example 1 sample Capacity retention after high temperature cycle (%) Volume expansion rate after high temperature storage (%) Example 1 65 97 Example 2 77 33 Example 3 93 13 Example 4 87 12 Example 5 70 9 Example 6 91 12 Example 7 87 15 Example 8 90 10 Example 9 89 10 Example 10 87 8 Example 11 87 12 Example 12 88 10 Example 13 94 11 Example 14 90 12 Example 15 93 8 Example 16 92 10 Example 17 91 12 Example 18 95 13 Example 19 85 16 Comparative example 1 37 122 Comparative example 2 38 118 Comparative example 3 55 5 Comparative example 4 35 138 Comparative Example 5 32 183 Comparative Example 6 25 228 Comparative Example 7 81 33 Comparative Example 8 79 28
  • the Example 1- has better high-temperature cycle performance and high-temperature storage performance than the secondary battery of Comparative Example 1 without adding any compound (A) under high-voltage (4.5V) working conditions, that is, higher high-temperature The capacity retention rate after cycling and the lower volume expansion rate after high temperature storage.
  • the compound (A4) possesses the functions of positive electrode film-forming protection and capture of transition metal ions dissolved in the electrolyte.
  • the protective effect of the electrolyte on the positive electrode material can be further strengthened, so that the high-temperature cycle performance and high-temperature storage performance of the secondary battery can be reliably improved.
  • the present application is not limited to the above-mentioned embodiments.
  • the above-mentioned embodiments are merely examples, and within the scope of the technical solutions of the present application, embodiments that have substantially the same configuration as the technical idea and exert the same effects are included in the technical scope of the present application.
  • various modifications conceivable by those skilled in the art are added to the embodiments, and other forms constructed by combining some components in the embodiments are also included in the scope of the present application. .

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Abstract

本申请提供了一种防止正极材料被侵蚀、防止过渡金属被溶出的电解液以及使用其的二次电池，该电解液中包含有机溶剂、以及一种或两种以上的通式(I)或通式(II)表示的化合物(A)，其中，化合物(A)在电解液中的含量为0.01wt％-5wt％，并且有机溶剂中碳酸乙烯酯的含量小于等于3wt％。本发明的二次电池具备优异的高电压工作条件下的循环寿命和存储性能。

Description

电解液及使用其的二次电池、电池模块、电池包以及用电装置 技术领域
本申请涉及二次电池技术领域，尤其涉及一种二次电池用电解液、使用其的二次电池、电池模块、电池包和用电装置。
背景技术
近年来，随着二次电池的应用范围越来越广泛，二次电池广泛应用于水力、火力、风力和太阳能电站等储能电源***，以及电动工具、电动自行车、电动摩托车、电动汽车、军事装备、航空航天等多个领域。二次电池一般由正极、负极、电解液等组成。例如，在锂离子二次电池中，通常是通过锂离子在正负极中的脱嵌并经由电解液中的电解质的传递实现电荷的转移，从而进行化学能和电能的相互转换。
但是，现有技术中，总是存在因电解液中所含的溶剂等对正极材料的侵蚀而导致正极材料结构坍塌以及其中的过渡金属的溶出，从而造成二次电池电芯容量衰减、电池循环寿命降低等问题。尤其是在高电压体系二次电池中，由于正极材料表面被侵蚀，当二次电池充电至高电压时，正极活性物质的氧化力变强，正极表面会发生持续氧化反应，从而造成二次电池电芯容量衰减的进一步加速。
发明内容
本申请是鉴于上述技术问题而进行的，其目的在于，提供一种防止正极材料被侵蚀、防止过渡金属被溶出的二次电池用电解液以及使用其的二次电池，从而能够提高二次电池的循环寿命和存储性能，尤其是在用于高电压(≥4.35V)下工作的二次电池的情况下也能够提升其循环寿命和存储性能。
本申请的第一方面提供了一种电解液，其包含有机溶剂、以及一 种或两种以上的下述通式(I)或通式(II)表示的化合物(A)，
Figure PCTCN2022070280-appb-000001
所述通式(I)或通式(II)中，
X选自O、S、N中的任意一种元素，
X为O时，R包括氰基或异氰酸基、三甲基硅基、碳原子数为2-4的直链烷基或支链烷基、部分氢或全部氢被卤素取代的碳原子数为1-4的直链烷基、部分氢或全部氢被卤素取代或不取代的苯基或苄基、部分氢或全部氢被卤素取代或不取代的磺酰基或磺酸基中一种或几种；X为S或N时，R包括氢原子、氰基或异氰酸基、三甲基硅基、碳原子数为1-4的直链烷基或支链烷基、部分氢或全部氢被卤素取代的碳原子数为1-4的直链烷基、部分氢或全部氢被卤素取代或不取代的苯基或苄基、部分氢或全部氢被卤素取代或不取代的磺酰基或磺酸基中的一种或几种，
所述化合物(A)在所述电解液中的含量为0.01wt％-5wt％，
所述有机溶剂中碳酸乙烯酯的含量小于等于3wt％。
由此，化合物(A)能够捕获溶解于电解液中的过渡金属离子，并且能够在正极成膜，保护正极材料，进一步，通过控制碳酸乙烯酯的含量，能够减少溶剂对正极材料的渗透侵蚀，减少正极材料中的过渡金属溶出，从而能够提高二次电池的循环寿命和存储性能，特别是在二次电池在高电压(≥4.35V)下工作的情况下，依然能够保持其循环寿命和存储性能。
在任意实施方式中，所述通式(I)或通式(II)中，X为O时，R包括氰基或异氰酸基、三甲基硅基、碳原子数为2-4的直链烷基、部分氢或全部氢被卤素取代的碳原子数为1-4的直链烷基、部分氢或全部氢被卤素取代或不取代的苯基或苄基、部分氢或全部氢被卤素取代或不 取代的磺酰基或磺酸基中的一种或几种；X为S或N时，R包括氰基或异氰酸基、三甲基硅基、氢原子、碳原子数为2-4的直链烷基、部分氢或全部氢被卤素取代的碳原子数为1-4的直链烷基、部分氢或全部氢被卤素取代或不取代的苯基或苄基、部分氢或全部氢被卤素取代或不取代的磺酰基或磺酸基中的一种或几种。
可选地，X为O时，R包括氰基或异氰酸基、三甲基硅基、碳原子数为2-3的直链烷基、部分氢或全部氢被卤素取代的碳原子数为1-3的直链烷基、部分氢或全部氢被卤素取代或不取代的苯基或苄基、部分氢或全部氢被卤素取代或不取代的磺酰基或磺酸基中的一种或几种；X为S或N时，R包括氰基或异氰酸基、三甲基硅基、氢原子、碳原子数为2-3的直链烷基、部分氢或全部氢被卤素取代的碳原子数为1-3的直链烷基、部分氢或全部氢被卤素取代或不取代的苯基或苄基、部分氢或全部氢被卤素取代或不取代的磺酰基或磺酸基中的一种或几种。
由此，能够进一步提高化合物(A)对正极材料的保护作用，能够进一步提升二次电池的循环寿命和存储性能。
在任意实施方式中，所述化合物(A)为选自下述化合物(A1)-(A12)中的一种或两种以上：
Figure PCTCN2022070280-appb-000002
Figure PCTCN2022070280-appb-000003
可选地，所述化合物(A)为选自上述化合物(A1)、(A2)、(A4)-(A6)、(A8)、(A9)、(A11)中的一种或两种以上。
由此，能够进一步提高化合物(A)对过渡金属离子的捕获能力，并提高化合物(A)在正极表面的成膜能力，从而进一步提高化合物(A)对正极材料的保护作用，能够更进一步提升二次电池的循环寿命和存储性能。
在任意实施方式中，化合物(A)在电解液中的含量为1wt％-5wt％，可选为2wt％-3wt％。由此能够兼顾化合物(A)对正极材料的保护作用以及电解液的离子传导能力，能够在不提高电池的内阻的前提下提升二次电池的循环寿命和存储性能。
在任意实施方式中，所述有机溶剂中不含碳酸乙烯酯(EC)。由 此，可以进一步降低电解液中溶剂对正极材料的渗透侵蚀，能够进一步防止因过渡金属离子溶解于电解液中所导致的正极材料结构坍塌，从而能够进一步提升电池的循环寿命和存储性能。
在任意实施方式中，有机溶剂中含有选自链状碳酸酯、碳酸乙烯酯以外的环状碳酸酯、羧酸酯和醚类溶剂中的一种或两种以上。由此，能够在碳酸乙烯酯的含量降低的情况下依然保证电解液具有足够的离子传导能力，从而能够确实地提升电池的循环寿命和存储性能。
在任意实施方式中，上述链状碳酸酯在电解液中的含量为40wt％-90wt％。由此，能够兼顾电解液对正极材料的保护作用和电解液的离子传导能力，从而能够确实地提升电池的循环寿命和存储性能。
在任意实施方式中，上述链状碳酸酯选自碳酸二甲酯、二乙基碳酸酯、二丙基碳酸酯、碳酸甲乙酯、碳酸甲丙酯、碳酸乙丙酯、三氟乙基甲基碳酸酯，上述碳酸乙烯酯以外的环状碳酸酯选自氟代碳酸乙烯酯，上述羧酸酯选自乙酸乙酯、乙酸甲酯、乙酸丙酯，上述醚类溶剂选自1,1,2,2-四氟乙基-2,2,2-三氟乙基醚、地氟醚、2,2,2-三氟乙基-30,30,30,20,20-五氟丙基醚。由此，能够使得电解液具有良好的离子传导能力，从而能够确实地提升电池的循环寿命和存储性能。
本申请的第二方面提供一种二次电池，其包括本申请第一方面的电解液。
本申请的第三方面提供一种电池模块，其包括本申请的第二方面的二次电池。
本申请的第四方面提供一种电池包，其包括本申请的第三方面的电池模块。
本申请的第五方面提供一种用电装置，其包括选自本申请的第二方面的二次电池、本申请的第三方面的电池模块或本申请的第四方面的电池包中的至少一种。
由此，能够提供提高了循环寿命和存储性能，尤其是提高了在高电压(≥4.35V)下工作的循环寿命和存储性能的二次电池、以及包括该二次电池的电池模块、电池包和用电装置。
附图说明
图1是本申请一个实施方式的二次电池的示意图。
图2是图1所示的本申请一个实施方式的二次电池的分解图。
图3是本申请一个实施方式的电池模块的示意图。
图4是本申请一个实施方式的电池包的示意图。
图5是图4所示的本申请一个实施方式的电池包的分解图。
图6是本申请一个实施方式的用电装置的示意图。
附图标记说明：
1电池包；2上箱体；3下箱体；4电池模块；5二次电池；51壳体；52电极组件；53顶盖组件。
具体实施方式
以下，适当地参照附图详细说明具体公开了本申请的电解液、二次电池、电池模块、电池包和电学装置的实施方式。但是会有省略不必要的详细说明的情况。例如，有省略对已众所周知的事项的详细说明、实际相同结构的重复说明的情况。这是为了避免以下的说明不必要地变得冗长，便于本领域技术人员的理解。此外，附图及以下说明是为了本领域技术人员充分理解本申请而提供的，并不旨在限定权利要求书所记载的主题。
本申请所公开的“范围”以下限和上限的形式来限定，给定范围是通过选定一个下限和一个上限进行限定的，选定的下限和上限限定了特别范围的边界。这种方式进行限定的范围可以是包括端值或不包括端值的，并且可以进行任意地组合，即任何下限可以与任何上限组合形成一个范围。例如，如果针对特定参数列出了60-120和80-110的范围，理解为60-110和80-120的范围也是预料到的。此外，如果列出的最小范围值1和2，和如果列出了最大范围值3，4和5，则下面的范围可全部预料到：1-3、1-4、1-5、2-3、2-4和2-5。在本申请中，除非有其他说明，数值范围“a-b”表示a到b之间的任意实数组合的缩 略表示，其中a和b都是实数。例如数值范围“0-5”表示本文中已经全部列出了“0-5”之间的全部实数，“0-5”只是这些数值组合的缩略表示。另外，当表述某个参数为≥2的整数，则相当于公开了该参数为例如整数2、3、4、5、6、7、8、9、10、11、12等。
如果没有特别的说明，本申请的所有实施方式以及可选实施方式可以相互组合形成新的技术方案。
如果没有特别的说明，本申请的所有技术特征以及可选技术特征可以相互组合形成新的技术方案。
如果没有特别的说明，本申请的所有步骤可以顺序进行，也可以随机进行，优选是顺序进行的。例如，所述方法包括步骤(a)和(b)，表示所述方法可包括顺序进行的步骤(a)和(b)，也可以包括顺序进行的步骤(b)和(a)。例如，所述提到所述方法还可包括步骤(c)，表示步骤(c)可以任意顺序加入到所述方法，例如，所述方法可以包括步骤(a)、(b)和(c)，也可包括步骤(a)、(c)和(b)，也可以包括步骤(c)、(a)和(b)等。
如果没有特别的说明，本申请所提到的“包括”和“包含”表示开放式，也可以是封闭式。例如，所述“包括”和“包含”可以表示还可以包括或包含没有列出的其他组分，也可以仅包括或包含列出的组分。
如果没有特别的说明，在本申请中，术语“或”是包括性的。举例来说，短语“A或B”表示“A，B，或A和B两者”。更具体地，以下任一条件均满足条件“A或B”：A为真(或存在)并且B为假(或不存在)；A为假(或不存在)而B为真(或存在)；或A和B都为真(或存在)。
现有技术中，由于电解液中的锂盐与极微量水等反应可能产生氢氟酸等杂质，这些杂质酸类可能会腐蚀正极材料，溶出正极材料中的过渡金属等活性物质，从而会导致正极材料结构的坍塌，并直接导致电池存储性能降低、电池循环寿命降低等问题。另外，在电池在高电压体系下工作的情况下，正极材料表面更容易发生氧化还原反应，正极材料中的过渡金属离子在电解液的作用下加速溶出，从而严重地制约了正极材料电化学性能的发挥，还会导致***等电池安全问题。
本申请发明人从电解液的角度出发进行研究，一方面通过在电解液中添加特定的添加剂，该添加剂能够在电极表面成膜，保护正极材料，另一方面通过对电解液的成分的调节，减少电解液中会侵蚀正极材料的成分的含量，从而协同保护正极材料不被电解液侵蚀溶出，提升电池的循环寿命和存储性能，特别在电池在高电压下工作的情况下，也能够保护正极材料，稳定二次电池的存储性能，提高二次电池的循环寿命。
[电解液]
本申请的一个实施方式中提出了一种电解液，其包含有机溶剂、以及一种或两种以上的下述通式(I)或通式(II)表示的化合物(A)，上述化合物(A)在电解液中的含量为0.01wt％-5wt％，并且所述有机溶剂中碳酸乙烯酯的含量小于等于3wt％。
Figure PCTCN2022070280-appb-000004
(所述通式(I)或通式(II)中，X选自O、S、N中的任意一种元素。在X为O时，R包括氰基或异氰酸基、三甲基硅基、碳原子数为2-4的直链烷基或支链烷基、部分氢或全部氢被卤素取代的碳原子数为1-4的直链烷基、部分氢或全部氢被卤素取代或不取代的苯基或苄基、部分氢或全部氢被卤素取代或不取代的磺酰基或磺酸基中的一种或几种；在X为S或N时，R包括氢原子、氰基或异氰酸基、三甲基硅基、碳原子数为1-4的直链烷基或支链烷基、部分氢或全部氢被卤素取代的碳原子数为1-4的直链烷基、部分氢或全部氢被卤素取代或不取代的苯基或苄基、部分氢或全部氢被卤素取代或不取代的磺酰基或磺酸基中的一种或几种。)
本申请人意外地发现：本申请通过在电解液中以上述特定范围含有上述特定的化合物(A)，并且降低有机溶剂中常用的碳酸乙烯酯的 含量，从而不仅能够降低电解液对正极材料的侵蚀力，还能够在正极材料表面形成保护膜，从而能够确实地保护正极材料不受电解液的侵蚀溶解，并提高二次电池的循环寿命和存储性能。
虽然机理尚不明确，但本发明的申请人猜测如下。上述特定的化合物(A)对过渡金属具有络合能力，因此能够捕获溶解于电解液中的过渡金属离子，防止过渡金属被电解液溶出，另外，该特定的化合物(A)对正极材料具有一定的吸附作用，可在正极材料表面成膜，保护正极材料不受电解液的侵蚀。
此外，现有技术中为了提高电解液的电导率而一直以来都在电解液中使用含有较多碳酸乙烯酯(EC)的有机溶剂。但是，在电池循环或存储过程中，碳酸乙烯酯溶剂会不断扩散穿透正极材料表面的SEI膜，与正极活性材料颗粒表面直接接触，并发生氧化分解。而且在该氧化分解过程中，还经常伴随产气、释氧、以及酸性物质的形成等副反应，所产生的酸性物质进一步腐蚀正极材料，从而导致过渡金属的进一步溶出，进一步加速电芯容量衰减。因此，通过减少电解液中的碳酸乙烯酯含量可以减少电解液中溶剂对正极材料的侵蚀，进一步强化电解液对正极材料的保护作用。
在一些实施方式中，上述通式(I)或通式(II)中，在X为O时，R包括氰基或异氰酸基、三甲基硅基、碳原子数为2-4的直链烷基、部分氢或全部氢被卤素取代的碳原子数为1-4的直链烷基、部分氢或全部氢被卤素取代或不取代的苯基或苄基、部分氢或全部氢被卤素取代或不取代的磺酰基或磺酸基中的一种或几种；在X为S或N时，R包括氰基或异氰酸基、三甲基硅基、氢原子、碳原子数为2-4的直链烷基、部分氢或全部氢被卤素取代的碳原子数为1-4的直链烷基、部分氢或全部氢被卤素取代或不取代的苯基或苄基、部分氢或全部氢被卤素取代或不取代的磺酰基或磺酸基中的一种或几种。可选地，在X为O时，R包括氰基或异氰酸基、三甲基硅基、碳原子数为2-3的直链烷基、部分氢或全部氢被卤素取代的碳原子数为1-3的直链烷基、部分氢或全部氢被卤素取代或不取代的苯基或苄基、部分氢或全部氢被卤素取代或不取代的磺酰基或磺酸基中的一种或几种；在X为S或N时，R包括 氰基或异氰酸基、三甲基硅基、氢原子、碳原子数为2-3的直链烷基、部分氢或全部氢被卤素取代的碳原子数为1-3的直链烷基、部分氢或全部氢被卤素取代或不取代的苯基或苄基、部分氢或全部氢被卤素取代或不取代的磺酰基或磺酸基中的一种或几种。
通过选择合适的X和R，从而能够增强化合物(A)对过渡金属离子的络合能力，并提高化合物(A)对正极材料表面的吸附性，从而进一步提高化合物(A)对过渡金属离子的捕获能力，提高化合物(A)在正极表面的成膜性，从而有效地阻止过渡金属离子溶解于电解液中，保护正极材料不受电解液的侵蚀。
在一些实施方式中，上述化合物(A)为选自下述化合物(A1)-(A12)中的一种或两种以上。可选地，化合物(A)为选自化合物(A1)、(A2)、(A4)-(A6)、(A8)、(A9)、(A11)中的一种或两种以上。
Figure PCTCN2022070280-appb-000005
Figure PCTCN2022070280-appb-000006
由此，化合物(A)能够高效地捕获正极材料中溶出的过渡金属离子，并且容易在正极材料表面成膜，从而能够良好地保护正极材料不被电解液侵蚀。
在一些实施方式中，化合物(A)在电解液中的含量为1wt％-5wt％，可选为2wt％-3wt％。如果化合物(A)在电解液中的含量过少，则不能在正极表面形成良好的界面膜，难以阻止在高电压下溶剂的分解以及过渡金属的溶出。如果化合物(A)在电解液中的含量过多，则会增加电解液的粘度，增大锂离子迁移阻力，并且在正极表面形成的界面膜过厚，导致二次电池的膜阻抗和电荷转移阻抗过大。
在一些实施方式中，有机溶剂中实质上不含碳酸乙烯酯。由此，可以完全消除碳酸乙烯酯对正极材料的影响，防止过渡金属被侵蚀溶出。
在一些实施方式中，有机溶剂中含有选自链状碳酸酯、碳酸乙烯酯以外的环状碳酸酯、羧酸酯和醚类溶剂中的一种或两种以上。由此，可以替代现有技术中常用的碳酸乙烯酯的作用，从而在减少电解液对正极材料的侵蚀的同时，还能够保证电解液的电导率，保证二次电池的充放电的正常进行，由此能够确实地提升电池的循环寿命和存储性 能。
在一些实施方式中，链状碳酸酯在电解液中的含量为40wt％-90wt％。由此，能够兼顾电解液对正极材料的保护作用和电解液的离子传导能力，从而能够确实地提升电池的循环寿命和存储性能。
在一些实施方式中，上述链状碳酸酯选自碳酸二甲酯、二乙基碳酸酯、二丙基碳酸酯、碳酸甲乙酯、碳酸甲丙酯、碳酸乙丙酯、三氟乙基甲基碳酸酯；上述碳酸乙烯酯以外的环状碳酸酯选自氟代碳酸乙烯酯；上述羧酸酯选自乙酸乙酯、乙酸甲酯、乙酸丙酯；上述醚类溶剂选自1,1,2,2-四氟乙基-2,2,2-三氟乙基醚、地氟醚、2,2,2-三氟乙基-30,30,30,20,20-五氟丙基醚。由此，能够使得电解液具有良好的离子传导能力，从而能够确实地提升电池的循环寿命和存储性能。
在一些实施方式中，电解液中的有机溶剂含量为60wt％-98wt％。
在一些实施方式中，有机溶剂还可包含选自1,4-丁内酯、环丁砜、二甲砜、甲乙砜及二乙砜等中的任意种。
在一些实施方式中，电解液进一步包含电解质盐，其中，电解质盐可选自六氟磷酸锂、四氟硼酸锂、高氯酸锂、六氟砷酸锂、双氟磺酰亚胺锂、双三氟甲磺酰亚胺锂、三氟甲磺酸锂、二氟磷酸锂、二氟草酸硼酸锂、二草酸硼酸锂、二氟二草酸磷酸锂及四氟草酸磷酸锂中的至少一种。
在一些实施方式中，所述电解液还可选地包括负极成膜添加剂等其它添加剂，还可以包括能够改善电池某些性能的添加剂，例如改善电池过充性能的添加剂、改善电池高温或低温性能的添加剂等。
另外，以下适当参照附图对本申请的二次电池、电池模块、电池包和用电装置进行说明。
[二次电池]
本申请的一个实施方式中，提供一种二次电池。
通常情况下，二次电池包括正极极片、负极极片、电解液和隔离膜。在电池充放电过程中，活性离子在正极极片和负极极片之间往返嵌入和脱出。电解液在正极极片和负极极片之间起到传导离子的作用。隔离膜设置在正极极片和负极极片之间，主要起到防止正负极短路的 作用，同时可以使离子通过。
本实施方式的二次电池中所具有的电解液是上述实施方式中提供的电解液。
[正极极片]
正极极片包括正极集流体以及设置在正极集流体至少一个表面的正极膜层，所述正极膜层包括正极活性材料。
作为示例，正极集流体具有在其自身厚度方向相对的两个表面，正极膜层设置在正极集流体相对的两个表面的其中任意一者或两者上。
在一些实施方式中，所述正极集流体可采用金属箔片或复合集流体。例如，作为金属箔片，可采用铝箔。复合集流体可包括高分子材料基层和形成于高分子材料基层至少一个表面上的金属层。复合集流体可通过将金属材料(铝、铝合金、镍、镍合金、钛、钛合金、银及银合金等)形成在高分子材料基材(如聚丙烯(PP)、聚对苯二甲酸乙二醇酯(PET)、聚对苯二甲酸丁二醇酯(PBT)、聚苯乙烯(PS)、聚乙烯(PE)等的基材)上而形成。
在一些实施方式中，正极活性材料可采用本领域公知的用于电池的正极活性材料。作为示例，正极活性材料可包括以下材料中的至少一种：橄榄石结构的含锂磷酸盐、锂过渡金属氧化物及其各自的改性化合物。但本申请并不限定于这些材料，还可以使用其他可被用作电池正极活性材料的传统材料。这些正极活性材料可以仅单独使用一种，也可以将两种以上组合使用。其中，锂过渡金属氧化物的示例可包括但不限于锂钴氧化物(如LiCoO 2)、锂镍氧化物(如LiNiO 2)、锂锰氧化物(如LiMnO 2、LiMn 2O 4)、锂镍钴氧化物、锂锰钴氧化物、锂镍锰氧化物、锂镍钴锰氧化物(如LiNi 1/3Co 1/3Mn 1/3O 2(也可以简称为NCM 333)、LiNi 0.5Co 0.2Mn 0.3O 2(也可以简称为NCM 523)、LiNi 0.5Co 0.25Mn 0.25O 2(也可以简称为NCM 211)、LiNi 0.6Co 0.2Mn 0.2O 2(也可以简称为NCM 622)、LiNi 0.8Co 0.1Mn 0.1O 2(也可以简称为NCM 811)、锂镍钴铝氧化物(如LiNi 0.85Co 0.15Al 0.05O 2)及其改性化合物等中的至少一种。橄榄石结构的含锂磷酸盐的示例可包括但不限于磷酸铁锂(如LiFePO 4(也可以简称为LFP))、磷酸铁锂与碳的复合材料、磷酸锰锂 (如LiMnPO 4)、磷酸锰锂与碳的复合材料、磷酸锰铁锂、磷酸锰铁锂与碳的复合材料中的至少一种。
在一些实施方式中，正极膜层还可选地包括粘结剂。作为示例，所述粘结剂可以包括聚偏氟乙烯(PVDF)、聚四氟乙烯(PTFE)、偏氟乙烯-四氟乙烯-丙烯三元共聚物、偏氟乙烯-六氟丙烯-四氟乙烯三元共聚物、四氟乙烯-六氟丙烯共聚物及含氟丙烯酸酯树脂中的至少一种。
在一些实施方式中，正极膜层还可选地包括导电剂。作为示例，所述导电剂可以包括超导碳、乙炔黑、炭黑、科琴黑、碳点、碳纳米管、石墨烯及碳纳米纤维中的至少一种。
在一些实施方式中，可以通过以下方式制备正极极片：将上述用于制备正极极片的组分，例如正极活性材料、导电剂、粘结剂和任意其他的组分分散于溶剂(例如N-甲基吡咯烷酮)中，形成正极浆料；将正极浆料涂覆在正极集流体上，经烘干、冷压等工序后，即可得到正极极片。
[负极极片]
负极极片包括负极集流体以及设置在负极集流体至少一个表面上的负极膜层，所述负极膜层包括负极活性材料。
作为示例，负极集流体具有在其自身厚度方向相对的两个表面，负极膜层设置在负极集流体相对的两个表面中的任意一者或两者上。
在一些实施方式中，所述负极集流体可采用金属箔片或复合集流体。例如，作为金属箔片，可以采用铜箔。复合集流体可包括高分子材料基层和形成于高分子材料基材至少一个表面上的金属层。复合集流体可通过将金属材料(铜、铜合金、镍、镍合金、钛、钛合金、银及银合金等)形成在高分子材料基材(如聚丙烯(PP)、聚对苯二甲酸乙二醇酯(PET)、聚对苯二甲酸丁二醇酯(PBT)、聚苯乙烯(PS)、聚乙烯(PE)等的基材)上而形成。
在一些实施方式中，负极活性材料可采用本领域公知的用于电池的负极活性材料。作为示例，负极活性材料可包括以下材料中的至少一种：人造石墨、天然石墨、软炭、硬炭、硅基材料、锡基材料和钛酸锂等。所述硅基材料可选自单质硅、硅氧化合物、硅碳复合物、硅 氮复合物以及硅合金中的至少一种。所述锡基材料可选自单质锡、锡氧化合物以及锡合金中的至少一种。但本申请并不限定于这些材料，还可以使用其他可被用作电池负极活性材料的传统材料。这些负极活性材料可以仅单独使用一种，也可以将两种以上组合使用。
在一些实施方式中，负极膜层还可选地包括粘结剂。所述粘结剂可选自丁苯橡胶(SBR)、聚丙烯酸(PAA)、聚丙烯酸钠(PAAS)、聚丙烯酰胺(PAM)、聚乙烯醇(PVA)、海藻酸钠(SA)、聚甲基丙烯酸(PMAA)及羧甲基壳聚糖(CMCS)中的至少一种。
在一些实施方式中，负极膜层还可选地包括导电剂。导电剂可选自超导碳、乙炔黑、炭黑、科琴黑、碳点、碳纳米管、石墨烯及碳纳米纤维中的至少一种。
在一些实施方式中，负极膜层还可选地包括其他助剂，例如增稠剂(如羧甲基纤维素钠(CMC-Na))等。
在一些实施方式中，可以通过以下方式制备负极极片：将上述用于制备负极极片的组分，例如负极活性材料、导电剂、粘结剂和任意其他组分分散于溶剂(例如去离子水)中，形成负极浆料；将负极浆料涂覆在负极集流体上，经烘干、冷压等工序后，即可得到负极极片。
[隔离膜]
在一些实施方式中，二次电池中还包括隔离膜。本申请对隔离膜的种类没有特别的限制，可以选用任意公知的具有良好的化学稳定性和机械稳定性的多孔结构隔离膜。
在一些实施方式中，隔离膜的材质可选自玻璃纤维、无纺布、聚乙烯、聚丙烯及聚偏二氟乙烯中的至少一种。隔离膜可以是单层薄膜，也可以是多层复合薄膜，没有特别限制。在隔离膜为多层复合薄膜时，各层的材料可以相同或不同，没有特别限制。
在一些实施方式中，正极极片、负极极片和隔离膜可通过卷绕工艺或叠片工艺制成电极组件。
在一些实施方式中，二次电池可包括外包装。该外包装可用于封装上述电极组件及电解液。
在一些实施方式中，二次电池的外包装可以是硬壳，例如硬塑料 壳、铝壳、钢壳等。二次电池的外包装也可以是软包，例如袋式软包。软包的材质可以是塑料，作为塑料，可列举出聚丙烯、聚对苯二甲酸丁二醇酯以及聚丁二酸丁二醇酯等。
本申请对二次电池的形状没有特别的限制，其可以是圆柱形、方形或其他任意的形状。例如，图1是作为一个示例的方形结构的二次电池5。
在一些实施方式中，参照图2，外包装可包括壳体51和盖板53。其中，壳体51可包括底板和连接于底板上的侧板，底板和侧板围合形成容纳腔。壳体51具有与容纳腔连通的开口，盖板53能够盖设于所述开口，以封闭所述容纳腔。正极极片、负极极片和隔离膜可经卷绕工艺或叠片工艺形成电极组件52。电极组件52封装于所述容纳腔内。电解液浸润于电极组件52中。二次电池5所含电极组件52的数量可以为一个或多个，本领域技术人员可根据具体实际需求进行选择。
在一些实施方式中，二次电池可以组装成电池模块，电池模块所含二次电池的数量可以为一个或多个，具体数量本领域技术人员可根据电池模块的应用和容量进行选择。
图3是作为一个示例的电池模块4。参照图3，在电池模块4中，多个二次电池5可以是沿电池模块4的长度方向依次排列设置。当然，也可以按照其他任意的方式进行排布。进一步可以通过紧固件将该多个二次电池5进行固定。
可选地，电池模块4还可以包括具有容纳空间的外壳，多个二次电池5容纳于该容纳空间。
在一些实施方式中，上述电池模块还可以组装成电池包，电池包所含电池模块的数量可以为一个或多个，具体数量本领域技术人员可根据电池包的应用和容量进行选择。
图4和图5是作为一个示例的电池包1。参照图4和图5，在电池包1中可以包括电池箱和设置于电池箱中的多个电池模块4。电池箱包括上箱体2和下箱体3，上箱体2能够盖设于下箱体3，并形成用于容纳电池模块4的封闭空间。多个电池模块4可以按照任意的方式排布于电池箱中。
另外，本申请还提供一种用电装置，所述用电装置包括本申请提供的二次电池、电池模块、或电池包中的至少一种。所述二次电池、电池模块、或电池包可以用作所述用电装置的电源，也可以用作所述用电装置的能量存储单元。所述用电装置可以包括移动设备(例如手机、笔记本电脑等)、电动车辆(例如纯电动车、混合动力电动车、插电式混合动力电动车、电动自行车、电动踏板车、电动高尔夫球车、电动卡车等)、电气列车、船舶及卫星、储能***等，但不限于此。
作为所述用电装置，可以根据其使用需求来选择二次电池、电池模块或电池包。
图6是作为一个示例的用电装置。该用电装置为纯电动车、混合动力电动车、或插电式混合动力电动车等。为了满足该用电装置对二次电池的高功率和高能量密度的需求，可以采用电池包或电池模块。
作为另一个示例的装置可以是手机、平板电脑、笔记本电脑等。该装置通常要求轻薄化，可以采用二次电池作为电源。
实施例
以下，说明本申请的实施例。下面描述的实施例是示例性的，仅用于解释本申请，而不能理解为对本申请的限制。实施例中未注明具体技术或条件的，按照本领域内的文献所描述的技术或条件或者按照产品说明书进行。所用试剂或仪器未注明生产厂商者，均可以为通过市购获得的常规产品。
实施例1-19、比较例1-8
(1)电解液的制备
实施例1-19以及比较例1-8的电解液均按照下述方法进行制备。
在含水量<10ppm的氩气气氛手套箱中，以链状碳酸酯的碳酸甲乙酯(EMC)作为主溶剂，将作为主溶剂的碳酸甲乙酯(EMC)和各辅助溶剂按照表1中所示的辅助溶剂与主溶剂的重量比(辅助溶剂：主溶剂(EMC))进行混合，得到混合溶剂。再将表1所示的化合物(A)以及充分干燥后的使得LiPF 6的浓度为1mol/L的锂盐LiPF 6溶解于上述混合溶剂中，搅拌均匀后，获得电解液。其中，表1中表示化合物(A)含量的重量百分数(wt％)是相对于电解液的重量百分数(wt％)。
(2)二次电池的制备
实施例1-19以及比较例1-8的二次电池均按照下述方法进行制备。
[负极片制备]
将负极活性物质石墨、导电剂乙炔黑、粘结剂丁苯橡胶、增稠剂羧甲基纤维素钠按照重量比为石墨:乙炔黑:丁苯橡胶:羧甲基纤维素钠＝95:2:2:1进行混合，加入去离子水后，充分搅拌混合，形成均匀的负极浆料；将此浆料涂覆于负极集流体铜箔上，然后烘干、冷压，得到负极片。
[正极片制备]
将正极活性材料NCM211(LiNi 0.5Co 0.25Mn 0.25O 2)、导电剂乙炔黑、粘结剂聚偏二氟乙烯按重量比97:2:1进行混合，加入溶剂N-甲基吡咯烷酮，充分搅拌混合后，形成均匀的正极浆料；将此浆料涂覆于正极集流体铝箔上，然后烘干、冷压，得到正极片。
[电池的制备]
将正极片、隔离膜、负极片按顺序叠好，使隔离膜处于正负极片之间起到隔离的作用，然后卷绕得到裸电芯；将裸电芯置于外包装箔中，将上述(1)中制备好的电解液注入到干燥后的裸电芯内，然后经过真空封装、静置、化成、整形等工序，获得二次电池。
【表1】
Figure PCTCN2022070280-appb-000007
注：表1中，“/”表示未添加任何种类的化合物(A)。“-”表示未添加辅助溶剂而仅使用了EMC作为溶剂。EC含量是表示相对于有机溶剂的重量百分数(wt％)。
对实施例1-19以及比较例1-8中所得到的二次电池按照下述方法测试其高电压工作条件下的高温循环性能以及高温存储性能，并将结果示于表2。
(1)二次电池的高温循环性能测试
制备好二次电池之后，在45℃下，先以0.5C的恒定电流对二次电 池充电至4.5V，进一步以4.5V恒定电压充电至电流为0.025C，然后以0.5C的恒定电流对二次电池放电至3.0V，此为一个充放电循环过程，并将此次的放电容量作为第1次循环的放电容量。将二次电池按上述方式进行循环充放电测试，并测定得到第100次循环的放电容量。按照下式计算二次电池的高温循环后的容量保持率(％)，并将结果示于表2中。
二次电池的高温循环后的容量保持率(％)＝[第100次循环的放电容量/第1次循环的放电容量]×100％。
(2)二次电池的高温存储性能测试
制备好二次电池之后，在25℃下，先以0.5C的恒定电流对二次电池充电至4.5V，进一步以4.5V恒定电压充电至电流为0.025C，然后在去离子水中用排水法测定二次电池的体积作为二次电池的初始体积(即，二次电池的高温存储前体积)，再将二次电池的表面干燥后置于60℃下存储30天，待存储结束后，测试二次电池的体积作为二次电池的高温存储后体积，并按下式计算二次电池的高温存储后的体积膨胀率(％)，并将结果示于表2中。
二次电池的高温存储后的体积膨胀率(％)＝[(二次电池的高温存储后体积-二次电池的初始体积)/二次电池的初始体积]×100％。
【表2】
样品 高温循环后的容量保持率(％) 高温存储后的体积膨胀率(％)
实施例1 65 97
实施例2 77 33
实施例3 93 13
实施例4 87 12
实施例5 70 9
实施例6 91 12
实施例7 87 15
实施例8 90 10
实施例9 89 10
实施例10 87 8
实施例11 87 12
实施例12 88 10
实施例13 94 11
实施例14 90 12
实施例15 93 8
实施例16 92 10
实施例17 91 12
实施例18 95 13
实施例19 85 16
比较例1 37 122
比较例2 38 118
比较例3 55 5
比较例4 35 138
比较例5 32 183
比较例6 25 228
比较例7 81 33
比较例8 79 28
从实施例1-5和比较例1-3的对比中可以看出，在使用不含EC(碳酸乙烯酯)作为溶剂的情况下，添加了适量的化合物(A4)的本发明实施例1-5的二次电池比不添加任何化合物(A)的比较例1的二次电池在高压(4.5V)工作条件下具有更好的高温循环性能以及高温存储性能，即，可以得到较高的高温循环后的容量保持率以及较低的高温存储后的体积膨胀率。这是由于化合物(A4)具备正极成膜保护及捕获溶解在电解液中的过渡金属离子的功能。但是当化合物(A4)含量 大于5wt％(比较例3)时，高温循环后的容量保持率反而出现恶化，这可能是因为化合物1占据了有机溶剂过大的比例，增加了电解液的粘度，导致锂离子迁移阻力增大，同时在正极表面形成的界面膜过厚，导致二次电池的膜阻抗和电荷转移阻抗太大，影响了二次电池的循环性能。而当化合物(A4)在电解液中的重量百分含量低至0.005wt％(比较例2)时，由于化合物(A4)的含量过少，不能有效地在正极表面形成良好的界面膜，因而难以阻止正极中的过渡金属的溶出，对二次电池性能的改善不明显。
另外，从实施例6-12与比较例1的对比中可知，通过使用符合通式(I)或(II)的多种化合物(A)的一种或两种以上作为添加剂均能够提高二次电池的高温循环性能以及高温存储性能，得到的二次电池在高压(4.5V)工作条件下均可以得到较高的高温循环后的容量保持率以及较低的高温存储后的体积膨胀率。这是由于这些化合物(A)对过渡金属元素具有相对较强的络合能力，另外一些化合物(A)所具有的F、三甲基硅基等取代基团对正极材料也具有一定的吸附作用，因此，都能发挥本申请发明所需的在正极表面成膜、捕获溶解于电解液中的过渡金属元素的功能。
另外，在将实施例3、15-19与比较例7、8进行比较的情况下可知，在添加等量的化合物(A)的情况下，使用含有5wt％以上的碳酸乙烯酯(EC)的有机溶剂的电解液所得到的二次电池的高温循环性能以及高温存储性能都明显变差。这样的趋势从不添加化合物(A)的情况下的比较例1与比较例4-6的对比中也能够观察得到。这是由于在有机溶剂中含有较多EC的情况下，EC会不断扩散穿透正极材料表面的SEI膜，与正极活性材料颗粒表面直接接触，从而发生氧化分解。而且在该氧化分解过程中，还伴随产气、释氧、以及酸性物质的形成等副反应，所产生的酸性物质进一步腐蚀正极材料，会导致过渡金属的进一步溶出，进一步加速电芯容量衰减。因此，通过减少电解液中的EC含量能够减少电解液对正极材料的侵蚀，提高二次电池的高温循环性能以及高温存储性能。进一步通过实施例3和实施例19的比较可知，通过将有机溶剂中的EC比例控制在3wt％以下时，基本可消除EC的侵 蚀作用及其产气的副作用。因此，通过在电解液的有机溶剂中进一步控制其中所含的碳酸乙烯酯的含量可以进一步强化电解液对正极材料的保护作用，从而能够确实地实现提高二次电池的高温循环性能以及高温存储性能。
需要说明的是，本申请不限定于上述实施方式。上述实施方式仅为示例，在本申请的技术方案范围内具有与技术思想实质相同的构成、发挥相同作用效果的实施方式均包含在本申请的技术范围内。此外，在不脱离本申请主旨的范围内，对实施方式施加本领域技术人员能够想到的各种变形、将实施方式中的一部分构成要素加以组合而构筑的其它方式也包含在本申请的范围内。

Claims (13)

  1. 一种电解液，其中，
    包含有机溶剂、以及一种或两种以上的下述通式(I)或通式(II)表示的化合物(A)，
    Figure PCTCN2022070280-appb-100001
    所述通式(I)或通式(II)中，
    X选自O、S、N中的任意一种元素，
    X为O时，R包括氰基或异氰酸基、三甲基硅基、碳原子数为2-4的直链烷基或支链烷基、部分氢或全部氢被卤素取代的碳原子数为1-4的直链烷基、部分氢或全部氢被卤素取代或不取代的苯基或苄基、部分氢或全部氢被卤素取代或不取代的磺酰基或磺酸基中的一种或几种；X为S或N时，R包括氢原子、氰基或异氰酸基、三甲基硅基、碳原子数为1-4的直链烷基或支链烷基、部分氢或全部氢被卤素取代的碳原子数为1-4的直链烷基、部分氢或全部氢被卤素取代或不取代的苯基或苄基、部分氢或全部氢被卤素取代或不取代的磺酰基或磺酸基中的一种或几种，
    所述化合物(A)在所述电解液中的含量为0.01wt％-5wt％，
    所述有机溶剂中碳酸乙烯酯的含量小于等于3wt％。
  2. 根据权利要求1所述的电解液，其中，
    所述通式(I)或通式(II)中，
    X为O时，R包括氰基或异氰酸基、三甲基硅基、碳原子数为2-4的直链烷基、部分氢或全部氢被卤素取代的碳原子数为1-4的直链烷基、部分氢或全部氢被卤素取代或不取代的苯基或苄基、部分氢或全部氢 被卤素取代或不取代的磺酰基或磺酸基中的一种或几种；X为S或N时，R包括氰基或异氰酸基、三甲基硅基、氢原子、碳原子数为2-4的直链烷基、部分氢或全部氢被卤素取代的碳原子数为1-4的直链烷基、部分氢或全部氢被卤素取代或不取代的苯基或苄基、部分氢或全部氢被卤素取代或不取代的磺酰基或磺酸基中的一种或几种，
    可选地，X为O时，R包括氰基或异氰酸基、三甲基硅基、碳原子数为2-3的直链烷基、部分氢或全部氢被卤素取代的碳原子数为1-3的直链烷基、部分氢或全部氢被卤素取代或不取代的苯基或苄基、部分氢或全部氢被卤素取代或不取代的磺酰基或磺酸基中的一种或几种；X为S或N时，R包括氰基或异氰酸基、三甲基硅基、氢原子、碳原子数为2-3的直链烷基、部分氢或全部氢被卤素取代的碳原子数为1-3的直链烷基、部分氢或全部氢被卤素取代或不取代的苯基或苄基、部分氢或全部氢被卤素取代或不取代的磺酰基或磺酸基中的一种或几种。
  3. 根据权利要求1或2所述的电解液，其中，
    所述化合物(A)为选自下述化合物(A1)-(A12)中的一种或两种以上：
    Figure PCTCN2022070280-appb-100002
    Figure PCTCN2022070280-appb-100003
    可选地，所述化合物(A)为选自上述化合物(A1)、(A2)、(A4)-(A6)、(A8)、(A9)、(A11)中的一种或两种以上。
  4. 根据权利要求1-3中任一项所述的电解液，其中，
    所述化合物(A)在所述电解液中的含量为1wt％-5wt％，可选为2wt％-3wt％。
  5. 根据权利要求1-4中任一项所述的电解液，其中，
    所述有机溶剂中不含碳酸乙烯酯。
  6. 根据权利要求1-5中任一项所述的电解液，其中，
    所述有机溶剂中含有选自链状碳酸酯、碳酸乙烯酯以外的环状碳酸酯、羧酸酯和醚类溶剂中的一种或两种以上。
  7. 根据权利要求6所述的电解液，其中，
    所述链状碳酸酯在所述电解液中的含量为40wt％-90wt％。
  8. 根据权利要求6或7所述的电解液，其中，
    所述链状碳酸酯选自碳酸二甲酯、二乙基碳酸酯、二丙基碳酸酯、碳酸甲乙酯、碳酸甲丙酯、碳酸乙丙酯、三氟乙基甲基碳酸酯，所述碳酸乙烯酯以外的环状碳酸酯选自氟代碳酸乙烯酯，所述羧酸酯选自乙酸乙酯、乙酸甲酯、乙酸丙酯，所述醚类溶剂选自1,1,2,2-四氟乙基-2,2,2-三氟乙基醚、地氟醚、2,2,2-三氟乙基-30,30,30,20,20-五氟丙基醚。
  9. 根据权利要求1-8中任一项所述的电解液，其中，
    所述有机溶剂在所述电解液中的含量为60wt％-98wt％。
  10. 一种二次电池，其包括权利要求1-9中任一项所述的电解液。
  11. 一种电池模块，其包括权利要求10所述的二次电池。
  12. 一种电池包，其包括权利要求11所述的电池模块。
  13. 一种用电装置，其包括选自权利要求10所述的二次电池、权利要求11所述的电池模块或权利要求12所述的电池包中的至少一种。
PCT/CN2022/070280 2022-01-05 2022-01-05 电解液及使用其的二次电池、电池模块、电池包以及用电装置 WO2023130249A1 (zh)

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