Electrolyte, application thereof and lithium ion battery

Abstract

The invention belongs to the technical field of lithium ion batteries, and particularly relates to an electrolyte, application thereof and a lithium ion battery. The electrolyte provided by the invention comprises a solvent and a lithium salt, wherein the solvent is perfluoropolyether ester and a halogenated amide compound. According to the invention, the perfluoropolyether ester contains high-content fluorine atom substitution, so that the perfluoropolyether ester is not easy to oxidize and decompose under a high-voltage condition, and an assembled battery can maintain a relatively high capacity retention rate; the halogenated amide compound is used as a cosolvent of the electrolyte, is preferentially decomposed under a high-voltage condition, and reacts on the surface of the positive electrode to form a layer of stable protective film to coat the surface of the high-voltage positive electrode in situ, so that direct contact between the electrode and the electrolyte is avoided, and the cycle stability of the lithium ion battery under high voltage is further improved; the halogenated amide compound has a high dielectric constant, can dissociate a large amount of lithium salt, promotes rapid conduction of ions, and is beneficial to improving the electrochemical performance of the electrolyte.

Description

technical field [0001] The invention belongs to the technical field of lithium ion batteries, and in particular relates to an electrolytic solution, an application thereof, and a lithium ion battery. Background technique [0002] In the current high-voltage lithium-ion batteries, the commercial electrolyte is mainly carbonate-based electrolyte. When the working voltage of the lithium-ion battery reaches above 4.3V, the electrolyte will undergo violent oxidation and decomposition reactions, and a large amount of gas will be generated, resulting in lithium The process of intercalation and delithiation of lithium-ion batteries cannot be carried out normally, resulting in the failure of lithium-ion batteries. In addition, during the cycle of high-voltage lithium-ion batteries, the cycle performance of the electrolyte will deteriorate due to the oxidative decomposition of the electrolyte and the side reactions of the positive active material itself (such as the precipitation of o...

AI Technical Summary

Problems solved by technology

[0002] In the current high-voltage lithium-ion batteries, the commercial electrolyte is mainly carbonate-based electrolyte. When the working voltage of the lithium-ion battery reaches above 4.3V, the electrolyte will undergo violent oxidation and decomposition reactions, and a large amount of gas will be generated, resulting in lithium The lithium-ion battery intercalation and de-lithium process cannot be carried out normally, resulting in the failure of the lithium-ion battery

In addition, during the cycle of high-voltage lithium-ion batteries, the cycle performance of the electrolyte will deteriorate due to the oxidative decomposition of the electrolyte and the side reactions of the positive active material itself (such as the precipitation of oxygen or the dissolution of transition metal ions), reducing the high Electrochemical performance of high-voltage lithium-ion batteries

[0003] At present, there is no electrolyte system for high-voltage lithium-ion batteries that can match higher specific capacity cathode materials

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