An electrolyte solution for improving the low-temperature performance of a lithium ion battery and a lithium ion battery containing the electrolyte solution

Abstract

The invention discloses an electrolytic solution for improving the low-temperature performance of a lithium ion battery and a lithium ion battery containing the electrolytic solution. The electrolytic solution includes a conductive lithium salt, a non-aqueous organic solvent and an additive. The additive is a multifunctional sulfite compound, and the additive simultaneously contains a sulfite group, a fluorine-containing alkyl group, an ether bond and an allyl group. Among them, the fluorine-containing alkyl group can increase the reduction potential of the additive, making it a good film-forming additive; the allyl group can improve the stability of the positive and negative electrode interfaces; the introduction of ether bonds can improve the flexibility of the electrode interface film, which is beneficial to improve The interface stability of the electrode material; the sulfite group can improve the ionic conductivity of the SEI film, which is beneficial to reduce the impedance of the battery at low temperature, thereby improving the low temperature performance of the battery. The present invention can not only significantly improve the low-temperature cycle performance of the lithium-ion battery by adding such additives in the electrolyte, but also not affect the normal and high-temperature performance of the battery.

Description

technical field [0001] The invention belongs to the field of new energy sources of lithium-ion batteries, and in particular relates to an electrolyte for improving the low-temperature performance of a lithium-ion battery and a lithium-ion battery containing the electrolyte. Background technique [0002] With the rapid development of science and technology, the space for human activities has been greatly expanded. Among them, activities such as polar regions, high-latitude and high-altitude areas, and deep space exploration are becoming more and more frequent. These require lithium-ion batteries with strong environmental adaptability and excellent low-temperature performance. Therefore, the development of lithium-ion batteries with excellent low-temperature performance is a relatively hot topic at home and abroad. At present, the low-temperature performance of lithium-ion batteries is generally poor, mainly due to the following reasons: first, the conductivity of the electrol...

AI Technical Summary

Problems solved by technology

Currently reported LiBOB, LiBF 4 LiDFOB and LiDFOB can significantly reduce the charge transfer resistance of the battery at low temperature and effectively improve the low-temperature discharge performance of lithium-ion batteries. However, due to the cost of lithium salts, it can only be used for theoretical research at this stage and cannot be promoted.

In terms of solvents, organic solvents with low melting points are mainly used to replace some carbonates, the most representative of which are linear carboxylates, such as ethyl acetate, methyl propionate, etc., which can significantly improve the performance of lithium-ion batteries as co-solvents. Low temperature discharge performance, but the introduction of carboxylate will deteriorate the high temperature performance of the battery

Relevant studies have shown that the introduction of fluorine-containing alkyl chains into carboxylate can improve the low-temperature performance of the battery without deteriorating the high-temperature performance of the battery. However, since the fluorine-containing carboxylate cannot be mass-produced at present, this method is still in the laboratory research stage.

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