Electrolyte additive, electrolyte and lithium secondary battery

Abstract

The invention discloses an electrolyte additive containing thiazolyl, amino and cyano, an electrolyte additive containing the additive and a lithium ion battery. The structure of the electrolyte additive is as shown in a structural formula I in the specification. The additive contains three effective groups, namely an imidazolyl group, an amino group and a nitrile group. Both thiazolyl and amino have alkalescence, so that HF in the electrolyte can be effectively reduced, precipitation of transition metal ions in the positive electrode of the lithium ion battery is reduced, and the stability of the positive electrode and an electrolyte interfacial film is enhanced; the cyano group can be complexed with transition metal of the positive electrode of the lithium ion battery to form a film on the surface of the positive electrode, and the interfacial film can effectively inhibit decomposition of electrolyte and reduce precipitation of transition metal ions. Therefore, the battery system containing the additive has better high voltage resistance, normal temperature and high temperature cycle performance and high temperature storage performance.

Description

technical field [0001] The invention relates to the technical field of lithium ion batteries, in particular to an electrolyte additive containing thiazole groups, amino groups and cyano groups, an electrolyte containing the additive, and a lithium ion battery. Background technique [0002] Since its inception in 1990, lithium-ion batteries have become one of the ideal secondary batteries internationally recognized for their advantages of high energy density, long cycle life, low environmental pollution and no memory effect, and have been widely used in mobile communications, portable Computers, electric bicycles and other electronic equipment. With the ever-expanding development of hybrid electric vehicles and pure electric vehicles, lithium-ion batteries, which are ideal power sources for electric vehicles, face unprecedented challenges—improving battery safety performance and energy density. [0003] Improving the working voltage of batteries is one of the effective ways ...

AI Technical Summary

Problems solved by technology

These high-voltage cathode materials have not been applied to actual production so far. The biggest reason is that the electrochemical stability window of the present commercial carbonate-based electrolyte is low. When the battery voltage reaches 4.5V (vs.Li / Li + ) or so, the electrolyte begins to undergo a violent oxidation and decomposition reaction, resulting in the failure of the lithium intercalation and desorption reactions of the battery to proceed normally.

Secondly, some positive electrode materials, such as LiNi0.5Mn1.5O4 materials, will dissolve metal Mn and Ni ions under high voltage conditions, destroying the material structure and causing serious battery capacity attenuation.

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