Lithium ion battery electrolyte solution

Abstract

The invention discloses a lithium ion battery electrolyte solution, and relates to the technical field of manufacturing of lithium ion batteries; the lithium ion battery electrolyte solution comprisesa lithium salt, a solvent, vinylene carbonate, an additive A and an additive B; the additive A is an ether nitrile compound or an aromatic compound, and the additive B is an organic ammonium salt; the ether nitrile compound is one of tetraethylene glycol dimethyl ether, ethylene glycol monobutyl ether, butanedinitrile or 1,3,6-hexanetricarbonitrile, the aromatic compound is one of thiophene, N-methylpyrrole or o-terophenyl, and the organic ammonium salt is ammonium benzoate or methyl ammonium benzoate. Based on the conventional additives, the combined additive of ether nitrile, the aromatic compound and the organic ammonium salt is added, a low-impedance, thin and dense SEI film is formed, and the battery internal resistance, the rate performance and the low-temperature performance are improved.

Description

technical field [0001] The invention relates to the technical field of manufacturing lithium ion batteries, in particular to an electrolyte solution for lithium ion batteries. Background technique [0002] At present, lithium-ion batteries, especially in the field of power batteries, automobile factories have higher and higher requirements for battery cycle performance, especially in summer high temperature weather, which has a great impact on the life of lithium-ion batteries. The existing technical solution is to add simple additives such as vinylene carbonate (VC) and propylene sulfite (PS) to the electrolyte to form a layer of SEI protective film on the surface of the negative electrode during battery charging. The HF generated by the electrolyte during the expansion process and the high-temperature cycle process will destroy the formed SEI film, and the cycle performance will drop significantly. [0003] Chinese Patent Publication No. CN1964123A, the patent publication...

AI Technical Summary

Problems solved by technology

The existing technical solution is to add simple additives such as vinylene carbonate (VC) and propylene sulfite (PS) to the electrolyte to form a layer of SEI protective film on the surface of the negative electrode during battery charging. The HF generated by the electrolyte during the expansion process and the high-temperature cycle process will destroy the formed SEI film, and the cycle performance will drop significantly.

[0003] Chinese Patent Publication No. CN1964123A, the patent publication date is May 16, 2007, discloses a non-aqueous electrolyte solution for lithium batteries, which contains conventional organic solvents, electrolyte salts and mixed additives, wherein the mixed additives include the following compound A At least one, at least one of compound B, at least one of compound C: compound A is selected from Li 2 CO 3 , Li 2 SO 4 , Li 2 SO 3 、LiNO 3 Inorganic lithium salt; compound B: vinylene carbonate, propylene carbonate; compound C: vinyl sulfite, propylene sulfite, dimethyl sulfoxide, diethyl sulfite, dimethyl sulfoxide , its weight ratio in the non-aqueous electrolyte is A: B: C=0.1%~3.0%: 0.5%~4.0%: 1.0%~5.0%; the invention provides a kind of SEI film that can form, can make the battery It is a non-aqueous electrolyte with better capacitance, cycle performance, and low-temperature electrochemical performance, but it also has serious shortcomings, that is, poor high-temperature performance, and the SEI film formed by it is stable at lower temperatures, but in higher temperature environments This kind of SEI becomes unstable under the environment, so that the performance of the lithium-ion battery prepared in the high-temperature environment drops sharply, and some serious accidents may even occur.

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