A lithium ion battery wide temperature electrolyte

Abstract

The invention discloses a wide-temperature electrolyte for lithium ion battery, which is characterized in that the electrolyte is composed of an ionic liquid like ether solvent, an auxiliary organic solvent and a low-temperature additive. The electrolyte has low viscosity and freezing point and can maintain high ionic conductivity at ultra-low temperature. Forming a thin and dense solid electrolyte membrane on the surface of the negative electrode; On the premise of maintaining good cycling performance at room temperature, the charge-discharge capability at low temperature and safety performance at high temperature are effectively improved, and the application range of lithium battery is effectively expanded.

Description

technical field [0001] The invention relates to a lithium-ion battery wide-temperature electrolyte, which belongs to the technical field of lithium-ion batteries. Background technique [0002] Since the commercial use of lithium-ion batteries in the 1990s, they have developed rapidly due to their advantages such as high specific energy, long cycle life, small size, and environmental friendliness. Today, lithium-ion batteries have been widely used in all aspects of our lives. They have not only become part of electronic products such as mobile phones, computers, and digital cameras, but also appear as a new energy source in the automotive, military, and aerospace fields. In the field of pure electric vehicles (EV) and hybrid electric vehicles (HEV), the temperature requirement for lithium-ion batteries is that they can be stored at a low temperature of -20°C and can be discharged at a low rate; stable operation in the environment. Therefore, it is particularly important to ...

AI Technical Summary

Problems solved by technology

When the temperature rises, on the one hand, the chain carbonate begins to volatilize or even decompose; on the other hand, the electrolyte and the electrode can react, causing a series of safety problems such as flatulence, and even an explosion

When the temperature is low, it is mainly affected by three aspects: first, as the temperature decreases, the viscosity of the cyclic carbonate increases or even solidifies, resulting in a decrease in ionic conductivity; second, the impedance of the SEI film increases, making charging and discharging The electrode polarization increases during the process; thirdly, lithium-ion batteries are prone to lithium precipitation in the later stages of charge and discharge, resulting in poor cycle performance

At the same time, the LiPF in this system 6 It will decompose at high temperature, be sensitive to water, easily produce HF to corrode the current collector, destroy the stability of the SEI film, dissolve the positive electrode material, and cause capacity attenuation and safety hazards, and the low conductivity at low temperature limits its low temperature. environment application

[0005] At present, commercially available electrolytes can fully cope with the normal use of lithium-ion batteries, but their low conductivity at low temperatures and potential safety hazards at high temperatures prevent them from being used in the automotive, military, and aerospace fields.

Images