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CN-122025825-A - Electrolyte, battery and electricity utilization device

CN122025825ACN 122025825 ACN122025825 ACN 122025825ACN-122025825-A

Abstract

The embodiment of the application provides an electrolyte, a battery and an electric device, wherein the electrolyte comprises lithium salt and a nonaqueous organic solvent, the nonaqueous organic solvent comprises fluorinated carbonate and fluoroether, the lithium salt comprises sulfonimide lithium salt, boron-based coordination anion lithium salt and phosphorus-containing inorganic lithium salt, multiple problems of high-voltage compatibility, lithium metal stability, current collector corrosion and the like can be solved under the conventional lithium salt concentration, and the problems of inherent high cost, high viscosity, poor low-temperature performance and the like of high-concentration electrolyte or local high-concentration electrolyte are avoided, and meanwhile, the electrolyte has excellent compatibility to lithium metal cathodes.

Inventors

  • DONG JIAMING
  • SHI YONG
  • WU JIAN

Assignees

  • 广州汽车集团股份有限公司

Dates

Publication Date
20260512
Application Date
20260212

Claims (10)

  1. 1. The electrolyte is characterized by comprising lithium salt and a nonaqueous organic solvent, wherein the nonaqueous organic solvent comprises fluorinated carbonate and fluoroether, and the lithium salt comprises lithium sulfonimide salt, boron-based coordination anion lithium salt and phosphorus-containing inorganic lithium salt.
  2. 2. The electrolyte according to claim 1, wherein the molar ratio of the phosphorus-containing inorganic lithium salt, the lithium sulfonimide salt, and the lithium boron-based coordinating anion salt is (0.1-0.5): 0.3-0.8): 0.1-0.4, and/or, The molar ratio of the fluorocarbonate to the fluorinated ether is (4-10): 1.
  3. 3. The electrolyte of claim 1 wherein the boron-based coordinating anion lithium salt comprises at least one of a boron-containing oxygen ring and a boron oxalate lithium salt.
  4. 4. The electrolyte of claim 1, wherein at least one of the following conditions is satisfied: (I) The lithium sulfonimide salt is at least one selected from lithium bis (fluorosulfonyl) imide, lithium bis (trifluoromethylsulfonyl) imide and lithium fluorosulfonyl-trifluoromethylsulfonyl imide; (II) the boron-based coordination anion lithium salt is at least one selected from lithium difluorooxalato borate, lithium bisoxalato borate and lithium tetrafluoroborate; (III) the phosphorus-containing inorganic lithium salt is at least one selected from lithium hexafluorophosphate, lithium difluorophosphate and lithium tetrafluorooxalate phosphate.
  5. 5. The electrolyte of claim 1, wherein the concentration of the lithium salt in the electrolyte is 0.8M to 1.5M.
  6. 6. The electrolyte of claim 1, wherein at least one of the following conditions is satisfied: (IV) the fluorinated carbonate is selected from the group consisting of fluoroethylene carbonate, bis-fluoroethylene carbonate, 2-fluoroethyl methyl carbonate, 2-difluoroethyl ethyl carbonate, methyltrifluoroethyl carbonate, ethyltrifluoroethyl carbonate, bis (2, 2-trifluoroethyl) carbonate, 2, 3-tetrafluoropropyl methyl carbonate at least one of 3, 3-trifluoropropylene carbonate, methyl hexafluoroisopropyl carbonate, ethyl hexafluoroisopropyl carbonate, 4-trifluoromethyl ethylene carbonate, bis (2, 2-difluoroethyl) carbonate, bis (pentafluorophenyl) carbonate, 2, 3-pentafluoropropyl ethyl carbonate; (V) the fluoroether is selected from the group consisting of 1, 2-tetrafluoroethyl-2, 3-tetrafluoropropyl ether, bis (2, 2-trifluoroethyl) ether 1, 2-tetrafluoroethyl-2, 2-trifluoroethyl ether 1H, 5H-octafluoropentyl-1, 2-tetrafluoroethyl ether 1, 2-tetrafluoroethyl ether, bis (2-fluoroethoxy) methane, 2-difluoro-1, 3-dimethoxypropane 1, 2-bis (1, 2-tetrafluoroethoxy) ethane and 1,2, 3-hexa-six at least one of fluoropropyl-1, 2-tetrafluoroethyl ether; (VI) the electrolyte further comprises at least one of a non-fluorinated ether comprising at least one of a non-fluorinated linear ether, a non-fluorinated cyclic ether, and a non-fluorinated ester comprising at least one of a non-fluorinated linear ester, a non-fluorinated cyclic ester.
  7. 7. The electrolyte of claim 6, wherein at least one of the following conditions is satisfied: (VII) the non-fluorinated ether is at least one selected from 1, 3-dioxolane, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, ethylene glycol diethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, and tetrahydrofuran; (VIII) the non-fluorinated ester is at least one selected from the group consisting of dimethyl carbonate, diethyl carbonate, methylethyl carbonate, methylpropyl carbonate, dipropyl carbonate, ethylene carbonate, and propylene carbonate.
  8. 8. A battery comprising a positive electrode sheet, a negative electrode sheet and the electrolyte according to any one of claims 1 to 7.
  9. 9. The battery of claim 8, wherein the negative electrode tab comprises metallic lithium.
  10. 10. An electric device comprising the battery according to claim 8 or 9 as a power supply source of the electric device.

Description

Electrolyte, battery and electricity utilization device Technical Field The application relates to the technical field of batteries, in particular to electrolyte, a battery and an electric device. Background Currently, lithium metal anodes are considered as a key system for achieving next generation high energy density energy storage due to their higher specific capacity (3861 mAh g -1) and lower electrochemical potential (-3.041V versus standard hydrogen electrode). However, its commercialization progress is severely limited by the compatibility issues of the electrolyte with the electrode interface. Currently, in order to improve the problem of lithium metal negative electrode interface compatibility, a high-activity lithium salt (such as lithium bis-fluorosulfonyl imide) is generally used to enhance the ionic conductivity and promote the formation of a better SEI film. However, the anion component in the electrolyte such as lithium bis-fluorosulfonyl imide can catalyze the oxidation and dissolution of aluminum foil under high pressure, so that the structure of a current collector is destroyed, the interface impedance is increased greatly, and the long-term cycle stability and the safety of the battery are seriously damaged. In the related art, in order to solve the problem of electrochemical corrosion of high-activity lithium salt to an aluminum current collector, a high-concentration electrolyte is adopted or a specific corrosion inhibitor is added, but the problems of cost increase, viscosity rapid increase (caused by the deterioration of wettability and low-temperature performance), lithium salting-out risk and the like are brought, and the solution has negative effects on other electrochemical performances (such as ion conductivity and negative electrode film forming dynamics) and severely restricts the practical application thereof. Disclosure of Invention The embodiment of the application provides an electrolyte, a battery and an electricity utilization device, and aims to solve the problems that the existing electrolyte cannot achieve high-voltage oxidation resistance, lithium metal compatibility, thermal safety and low current collector corrosion risk. In order to solve the problems, the application is realized by the following technical scheme: The application provides an electrolyte, which comprises lithium salt and a nonaqueous organic solvent, wherein the nonaqueous organic solvent comprises fluorinated carbonate and fluoroether, and the lithium salt comprises lithium sulfonimide salt, boron-based coordination anion lithium salt and phosphorus-containing inorganic lithium salt. In the electrolyte provided by the embodiment of the application, a nonaqueous organic solvent comprising fluorinated carbonate and fluoroether is arranged, and a lithium salt comprising sulfonimide lithium salt, boron-based coordination anion lithium salt and phosphorus-containing inorganic lithium salt is arranged; the electrolyte can construct a dense and inorganic-rich positive electrode electrolyte interface (Cathode Electrolyte Interface, CEI) membrane at a positive electrode interface by utilizing the inherent high thermodynamic stability and high flash point characteristics of fluorocarbonate and fluoroether solvents, effectively inhibit the catalytic decomposition of a high-activity positive electrode material on the electrolyte, radically reduce heat and gas production, greatly reduce the risk of thermal runaway of a battery, enable the battery to smoothly pass through 130 ℃ and other severe thermal box safety tests, simultaneously, fluoroether and sulfonimide lithium salt can cooperatively construct a LiF-rich solid electrolyte interface membrane (Solid Electrolyte Interface, SEI) at a negative electrode side, remarkably reduce lithium deposition overpotential, promote uniform deposition of lithium ions, effectively inhibit growth of lithium dendrites and side reaction consumption of the electrolyte, and in addition, boron-based coordination anion lithium salt and phosphorus-containing inorganic lithium salt can generate preferential oxidation on the surface of an aluminum current collector at the positive electrode side to form a dense and stable passivation layer, synergistically inhibit corrosion of the sulfonimide lithium salt on the aluminum current collector under high voltage, so that the lithium salt is matched with the high-concentration electrolyte at high voltage, and the high-concentration electrolyte can be compatible with the conventional lithium electrolyte, the problems of high-concentration metal electrolyte and the inherent high-concentration electrolyte can be solved, the problem of high-concentration metal electrolyte and the inherent high-concentration electrolyte is solved, the high-concentration metal electrolyte is compatible with the high-concentration electrolyte, the problem of the high-concentration electrolyte is solved, and the inherent high-concentration electrolyte is compatib