Multifunctional high-voltage lithium ion battery electrolyte and high-voltage lithium ion battery

Abstract

The invention belongs to the technical field of lithium ion batteries. The multifunctional high-voltage lithium ion battery electrolyte comprises a lithium salt, a non-aqueous organic solvent and an additive, the additive comprises a difluorophosphoryl boron-accommodating compound, three substituent groups of the difluorophosphoryl boron-accommodating compound are respectively difluorophosphoryl-PO2F2 or-F, and at least one of the substituent groups is difluorophosphoryl. Compared with the prior art, the electrolyte disclosed by the invention not only can improve the high-temperature performance of the lithium ion battery under high voltage, but also greatly improves the cycle performance and the low-temperature performance of the battery. Meanwhile, the special additive also has a certaineffect of removing water and acid. In addition, the invention also provides a high-voltage lithium ion battery using the electrolyte.

Description

technical field [0001] The invention belongs to the technical field of lithium-ion batteries, and in particular relates to a multifunctional high-voltage lithium-ion battery electrolyte and a high-voltage lithium-ion battery. Background technique [0002] Lithium-ion secondary batteries have the advantages of high working voltage, high specific energy density, long cycle life, low self-discharge rate, no memory effect, and low environmental pollution. An ideal power source for power tools. In the technical field, increasing the working voltage or platform voltage of lithium-ion secondary batteries can effectively increase the energy density of lithium-ion batteries. [0003] At present, the charging cut-off voltage of lithium cobalt oxide battery is increased from 4.4V to 4.5V, and its effective capacity can be increased from 175mAh / g to about 220mAh / g. But at the same time, the performance of the battery is significantly reduced, especially the high-temperature cycle and ...

AI Technical Summary

Problems solved by technology

On the one hand, at high temperature, the LiPF in the electrolyte 6 It is extremely easy to decompose and produce HF to corrode the positive electrode active material, resulting in the dissolution of metal ions; on the other hand, under high voltage, the transition metal oxide of the positive electrode active material is easily reduced and dissolved, and the transition metal ion passes through the SEI film on the surface of the negative electrode. It is reduced to metal simple substance, which leads to the continuous increase of the negative electrode impedance and deteriorates the performance of the battery

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