Electrolyte for improving high temperature and high voltage performance of lithium ion battery and application thereof in lithium ion battery

Abstract

The invention discloses an electrolyte for improving high temperature and high voltage performance of a lithium ion battery and application thereof in the lithium ion battery. The electrolyte comprises lithium salt, organic solvent and additive, wherein the additive is composed of methoxyl diphenylphosphine and cathode surface film-forming additive, content of the methoxyl diphenylphosphine in the electrolyte is 0.01-10.0wt.%, and content of the cathode surface film-forming additive in the electrolyte is 0.02-5wt.%; the organic solvent is composed of 10-50wt.% of cyclic carbonate and 30-70wt.% of linear carbonate; and concentration of the lithium salt in the electrolyte is 0.5-2.5mol / L. According to the electrolyte provided by the invention, MDP and cathode surface film-forming additive are used simultaneously as combined additive, stability of a positive electrode material of the lithium ion battery under high voltage can be improved, decomposition of the electrolyte on surface of the positive electrode is inhibited, and cycle performance of the high-voltage lithium ion battery under normal temperature and high temperature is improved.

Description

Technical field [0001] The present invention belongs to the field of lithium -ion batteries, involving an electrolytic solution that improves the high temperature and high voltage performance of lithium -ion batteries, and lithium ion batteries including the electrolyte. Background technique [0002] As an important equipment for electrochemical energy conversion and storage, lithium -ion batteries are widely used in information technology, electric vehicles and hybrid vehicles, aerospace and other civilian and military fields.Especially in recent years, with the continuous promotion of new energy vehicles, the requirements and research on dynamic lithium -ion batteries have also developed rapidly.Especially in the field of electric vehicles, when the volume and weight of the battery are strictly limited, the energy density of the battery determines the single maximum mileage of electric vehicles. Therefore, the energy density of single batteries needs to continue to increase. ...

AI Technical Summary

Problems solved by technology

[0003] Increasing the voltage of lithium-ion batteries can increase the energy density of lithium-ion batteries. However, the voltage of lithium-ion batteries continues to increase. Higher voltage means that the positive electrode material has a higher electrode potential, and the oxidative decomposition of the electrolyte at the positive electrode is more serious. As the battery charge-discharge cycle progresses, the internal resistance of the battery gradually increases, which will lead to a decrease in the cycle and storage performance of the lithium-ion battery or even failure.

In addition, high temperature will increase the activity of the electrode material inside the battery, increase the side reactions, and the cycle performance of the battery will also decline rapidly.

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