Electrolyte for lithium metal battery and lithium metal battery thereof

Abstract

The invention discloses an electrolyte for a lithium metal battery and the lithium metal battery. The electrolyte comprises a mixed organic solvent and a mixed lithium salt, the mixed organic solvent comprises gamma-butyrolactone and linear carboxylic ester; the mixed lithium salt comprises a lithium salt I and a lithium salt II, the lithium salt I is halogenated lithium borate, and the lithium salt II is at least one of lithium difluorophosphate and lithium trioxalate phosphate. According to the invention, the traditional carbonate solvent is abandoned, the gamma-butyrolactone is selected as the basic solvent, and the linear carboxylic ester is cooperatively used, so that the conductivity of the electrolyte is improved, the viscosity is reduced, and the low-temperature capacity of the battery is improved. Furthermore, a small amount of FEC is added on the basis of the solvent, so that the decomposition of the linear carboxylic ester is reduced. Meanwhile, by using the mixed lithium salt, the electrolyte with good performance is obtained under the condition of relatively low lithium salt content; the reduction of the lithium salt content is beneficial to reducing the cost on one hand, and on the other hand, the electrolyte has relatively low viscosity at low temperature, so that the low-temperature cycle performance of the battery is improved.

Description

technical field [0001] The invention belongs to the technical field of lithium metal batteries, and particularly relates to an electrolyte for a lithium metal battery and a lithium metal battery thereof. Background technique [0002] Since its inception, lithium-ion batteries have become an indispensable part of human production and life, and batteries suitable for various conditions have also emerged with the development of economy and society. In some areas, the temperature will drop below -20°C in winter, and commercial lithium-ion batteries with traditional graphite anodes basically stop working below -20°C, so it is not practical to use graphite anodes at ultra-low temperatures. The theoretical specific capacity of lithium metal negative electrode is as high as 3860mA·h / g, which is 10 times that of graphite negative electrode material. 3 ), which has important implications for designing lithium batteries that can operate at low temperatures. The dendrite growth of lit...

AI Technical Summary

Problems solved by technology

LiBF 4 Good thermal stability, small charge transfer resistance, but poor film forming effect, it is difficult to meet commercial requirements when used alone

[0005] In the prior art, either only the solvent is modified, or only a new type of lithium salt is used, and there are few studies reporting the simultaneous modification of both.

And most electrolytes will reduce the electrochemical performance of lithium metal batteries at room temperature after modification.

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