High-temperature electrolyte and lithium ion battery

Abstract

The invention provides a high-temperature electrolyte and a lithium ion battery comprising the same. A borate or borane high-temperature agent which is added into the electrolyte can be used for preventing decomposition of LiPF6, reducing reaction of PF5 and a solvent, reducing generation of CO, Co2 and hydrocarbon gas and reducing excessive consumption of the electrolyte and can also be used for capturing F and reducing generation of HF, so that the stability of a positive active material and an SEI membrane are optimized, and the cycle property of the lithium ion battery is improved.

Description

【Technical field】 [0001] The invention relates to the technical field of lithium ion batteries, in particular to a high-temperature electrolyte and a lithium ion battery using the electrolyte. 【Background technique】 [0002] The electrolyte used as an ion transporter between the positive and negative electrodes of lithium-ion batteries needs to have high electrical conductivity, wide electrochemical window and high thermal stability. The electrolyte is mainly composed of lithium salts, organic solvents and functional additives, commonly used lithium salts include LiPF 6 , which has high room temperature conductivity, good electrochemical stability (no corrosion to the current collector), and excellent properties such as being easily soluble in carbonate organic solvents, but LiPF 6 Unstable and easy to decompose at high temperature and sensitive to trace water to form PF 5 , HF and LiF. HF causes the dissolution of active materials and the instability of the SEI film, res...

AI Technical Summary

Problems solved by technology

The electrolyte is mainly composed of lithium salts, organic solvents and functional additives, commonly used lithium salts include LiPF 6 , which has high room temperature conductivity, good electrochemical stability (no corrosion to the current collector), and excellent properties such as being easily soluble in carbonate organic solvents, but LiPF 6 Unstable and easy to decompose at high temperature and sensitive to trace water to form PF 5 , HF and LiF

HF causes active material dissolution and SEI film instability, leading to reversible capacity fading and continuous formation of SEI film, thus affecting battery performance

At the same time, PF 6 - and PF 5 It is easy to cause ring-opening reactions of solvents such as EC and PC to generate CO and CO 2 , hydrocarbon gases and organic and inorganic lithium salts, resulting in excessive air pressure, causing the battery to be broken and opened, and leakage, fire or even explosion

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