A high stability lithium ion battery electrolyte

Abstract

The invention discloses a high-stability lithium ion battery electrolyte which comprises lithium hexafluorophosphate, a nonaqueous solvent, an additive and an electrolyte stabilizing agent, wherein the electrolyte stabilizing agent is any one and more of tris(trimethylsilyl)phosphite, N, N-dimethylpropionamide and N-methyl-2-pyrrolidone. According to the invention, as P / N atoms in the electrolyte stabilizing agent have lone electron pairs, relatively low Lewis base property is achieved after a less amount of the electrolyte stabilizing agent is added into the electrolyte, the electrolyte stabilizing agent and PF5 can form a complex of six ligands, and accordingly the Lewis acidity and reaction activity of the PF5 are reduced and the colority rising caused by the reaction between the PF5 and trace impurities in the electrolyte is inhibited well; in addition, the stabilizing agent has good compatibility with a graphite cathode, and can react on the electrode surface after being added into the electrolyte to form a film, so that the cycle performance of the lithium ion battery is improved.

Description

technical field [0001] The invention relates to the field of lithium ion batteries, in particular to a highly stable lithium ion battery electrolyte. Background technique [0002] Lithium-ion batteries have the advantages of high specific energy, high voltage, long cycle life, and environmental friendliness, and are widely used in digital, energy storage, power, military aerospace, and communication equipment and other fields. [0003] As an important part of lithium-ion batteries, the electrolyte plays a role in transporting charge between the positive and negative electrodes of the battery, and is crucial to the capacity performance, cycle performance and high and low temperature performance of the battery. Lithium hexafluorophosphate is currently the only electrolyte lithium salt that is commercially used in large quantities. It has comprehensive advantages such as good solubility, high electrical conductivity, good film-forming performance, passivation of aluminum curren...

AI Technical Summary

Problems solved by technology

Although such additives help to suppress the rise of the chromaticity of the electrolyte, they are poorly compatible with graphite negative electrodes, and will also deteriorate the long-term cycle performance of the battery in the case of a small amount of addition.