High-temperature electrolyte and lithium battery

Abstract

The invention belongs to the field of lithium ion batteries, and particularly discloses a high-temperature electrolyte which comprises the following components in percentage by weight: 2-20% of lithium salt; 0.01%-20% of a high-temperature additive; 70%-90% of a non-aqueous organic solvent; and 0.1%-10% of other additives. The invention also provides a lithium battery which comprises a positive electrode, a negative electrode, a diaphragm and the electrolyte. The high-temperature additive added into the electrolyte contains a large number of anhydride groups, can form an interface film with good and stable performance on the surface of an electrode in battery circulation, inhibits dissolution of positive electrode metal ions at high temperature, participates in formation of a passive film on the surface of a negative electrode, modifies the structure and components of an SEI film, and improves the high-temperature and circulation performance of the battery; the introduced sulfonate group can form a stable SEI film on the surface of the negative electrode, the impedance of the SEI film is not increased after high-temperature storage, the capacity recovery rate is relatively high, and the high-temperature cycling stability of the battery is improved.

Description

technical field [0001] The invention relates to the field of lithium ion batteries, in particular to a high-temperature electrolyte and a lithium battery. Background technique [0002] Lithium-ion battery technology has been widely used in energy, transportation, aerospace, information, medical care, etc., such as power batteries, energy storage batteries, 3C consumer batteries, etc. At present, commercial lithium-ion battery electrolytes are mainly composed of non-aqueous organic solvents such as cyclic carbonates and linear carbonates, and lithium salts, but there are some problems in the application of existing commercial electrolyte systems, especially in some special In the environment, the performance of lithium-ion batteries will be greatly limited. [0003] At present, the existing electrolyte system has the following problems: under high temperature environment, the lithium hexafluorophosphate salt in the electrolyte will be decomposed into lithium fluoride and pho...

AI Technical Summary

Problems solved by technology

At present, commercial lithium-ion battery electrolytes are mainly composed of non-aqueous organic solvents such as cyclic carbonates and linear carbonates, and lithium salts, but there are some problems in the application of existing commercial electrolyte systems, especially in some special environment, the performance of lithium-ion batteries will be greatly limited

[0003] At present, the existing electrolyte system has the following problems: under high temperature environment, the lithium hexafluorophosphate salt in the electrolyte will be decomposed into lithium fluoride and phosphorus pentafluoride, which will react with the electrolyte solvent to generate hydrofluoric acid, which will lead to negative electrode SEI Decomposition of the membrane and corrosion of the electrode material, thereby reducing the cycle performance and service life of the battery

However, these lithium salts also have some problems when used in batteries. For example, lithium bisoxalate borate and lithium difluorophosphate have low solubility in electrolyte solvents, the SEI film of lithium tetrafluoroborate is unstable, and difluorosulfonyl Lithium imide and lithium bistrifluoromethanesulfonylimide will corrode aluminum foil and are expensive, etc.

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