Electrolyte and secondary lithium battery

Abstract

The invention provides an electrolyte and a secondary lithium battery. The electrolyte comprises a lithium salt, an organic solvent and additives. The additives include fluoroborate and lithium difluorophosphate. When the electrolyte is applied to the secondary lithium battery, the secondary lithium battery simultaneously has excellent high-temperature cycle performance, high-temperature storage performance, low-temperature discharge performance and large-rate charge performance, and the low-temperature lithium precipitation of the secondary lithium battery is also significantly suppressed.

Description

technical field [0001] The invention relates to the technical field of batteries, in particular to an electrolyte and a secondary lithium battery. Background technique [0002] The high energy density, long cycle life, wide operating temperature range, and environmental protection of lithium-ion secondary batteries have made them the main energy source for mobile electronic devices. In terms of user experience, people put forward higher and higher requirements for the charge and discharge rate of lithium-ion secondary batteries, that is, lithium-ion secondary batteries are required to have high-rate charge-discharge capabilities; in addition, higher environmental adaptability is also proposed. The current electronic products sometimes need to be used under extreme conditions, such as high or low temperature environments. Generally, compared with conventional environments, the performance of lithium-ion secondary batteries will deteriorate when used under extreme conditions. ...

AI Technical Summary

Problems solved by technology

However, in general, there are contradictions in improving the charge-discharge rate performance, low-temperature discharge performance and high-temperature performance of lithium-ion secondary batteries from the perspective of electrolyte.

On the one hand, the high-temperature performance can be improved by adding film-forming additives to passivate the positive-negative interface, but the charge-discharge rate performance and low-temperature discharge performance of lithium-ion secondary batteries are seriously deteriorated due to the increase of the positive-negative interface resistance at the same time.

On the other hand, optimizing the composition of organic solvents reduces the viscosity of the electrolyte at low temperatures and increases the conductivity. For example, by adding a large amount of low-viscosity organic solvents, the charge-discharge rate performance and low-temperature discharge performance of lithium-ion secondary batteries can be improved, but The high-temperature performance of lithium-ion secondary batteries usually deteriorates, which cannot finally solve the problems of lithium-ion secondary batteries in applications

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