Electrolyte for lithium ion battery and lithium ion battery comprising electrolyte

Abstract

The present invention provides an electrolyte for a lithium ion battery and a lithium ion battery comprising the electrolyte. The electrolyte comprises a non-aqueous organic solvent, an additive and aconductive lithium salt. The additive comprises a grafted polysilane compound and a low-impedance lithium salt compound. Si-H bonds in the grafted polysilane compound are oxidized and cross-linked onthe surface of a positive electrode to generate a protective film with relatively high rigidity and a Si-O-Si cross-linked structure, so that the grafted polysilane compound has relatively high thermal stability, and the safety performance and the high-temperature storage performance of a battery can be improved. Meanwhile, the polymer can be used in the battery charging and discharging process;a sulfur-containing cyclic ester group can be matched with a low-impedance lithium salt compound on the surface of a negative electrode in a ring opening manner to form a composite SEI film of thin-layer polysulfate with a tough structure and a low-impedance inorganic framework, and the SEI film has relatively high conductivity to Li <+>, so that the battery has excellent low-temperature dischargeperformance.

Description

technical field [0001] The invention belongs to the technical field of lithium ion batteries, and in particular relates to an electrolyte solution for lithium ion batteries and a lithium ion battery including the electrolyte solution. Background technique [0002] In recent years, lithium-ion batteries have been widely used in digital, energy storage, power, military aerospace and communication equipment and other fields. However, with the diversification of electronic equipment and the diversification of functions, the use environment and demand of consumers for lithium-ion batteries continue to increase, which requires lithium-ion batteries to have the characteristics of both high and low temperature performance. At the same time, there are potential safety hazards in the use of lithium-ion batteries. When the batteries are continuously under extreme conditions such as overcharging and discharging, serious safety accidents, fires or even explosions are prone to occur. [...

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Problems solved by technology

[0004] The purpose of the present invention is to solve the problem that the existing electrolyte additives are difficult to simultaneously improve high and low temperature performance and safety performance

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