Electrolyte for improving low-temperature performance of lithium ion battery and lithium ion battery containing electrolyte

Abstract

The invention discloses an electrolyte for improving low-temperature performance of a lithium ion battery and the lithium ion battery containing the electrolyte. The electrolyte comprises conductive lithium salt, a non-aqueous organic solvent and an additive, the additive is a polyfunctional sulfite compound, and the additive contains sulfite groups, fluorine-containing alkyl, ether bonds and allyl at the same time. The fluorine-containing alkyl can improve the reduction potential of the additive so that the additive becomes a good film-forming additive; allyl can improve the stability of positive and negative electrode interfaces; the introduction of the ether bonds can improve the flexibility of an electrode interface film, and is beneficial to improving the interface stability of an electrode material; and the sulfite groups can improve ionic conductivity of an SEI film, and are beneficial to reducing the impedance of the battery at a low temperature so that the low-temperature performance of the battery is improved. By adding the additive into the electrolyte, the low-temperature cycle performance of the lithium ion battery can be obviously improved, and the normal-temperatureperformance and the high-temperature performance of the battery are not influenced.

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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