Lithium ion battery high-voltage electrolyte solution capable of constructing double-layer positive electrode surface film

Abstract

The invention discloses a lithium ion battery high-voltage electrolyte solution capable of constructing a double-layer positive electrode surface film, and belongs to the technical field of manufacturing of lithium ion batteries. The electrolyte solution is composed of an organic solvent, a lithium salt and a film-forming additive; the organic solvent is composed of cyclocarbonate, linear carbonate and fluoroethylene carbonate; the film-forming additive is composed of a film-forming additive A, a film-forming additive B and a film-forming additive C, wherein the film-forming additive A is oneof tri(trimethylsilane)borate or tri(trimethylsilane)phosphate, the film-forming additive B is methylene methanedisulfonate, and the film-forming additive C is one of thiophene or 3,4-ethylenedioxythiophene. Through combined use of the three film-forming additives, the electrolyte solution generates double layers of positive electrode surface films with different components, an electrode / electrolyte solution interface can be stabilized, oxidation decomposition of the electrolyte solution and damage of a positive electrode material structure are inhibited, the battery cycle stability and thermal stability are improved, the internal resistance of the battery is reduced, and the battery multiplying power performance is improved.

Description

technical field [0001] The invention relates to the technical field of lithium-ion battery manufacturing, in particular to a high-voltage electrolyte solution for a lithium-ion battery capable of constructing a double-layer positive electrode surface film. Background technique [0002] Increasing the charge cut-off voltage is one of the effective ways to increase the energy density of lithium-ion batteries. At present, the electrolyte of commercial lithium-ion batteries, once the charging cut-off voltage exceeds 4.5V, the conventional carbonate-based electrolyte will be oxidized and decomposed, resulting in an increase in the internal resistance of the battery, which will lead to a decrease in the cycle performance of the entire battery. In order to make the electrolyte meet the working requirements under high pressure, it is mainly improved from two aspects: solvent and film-forming additives. The film-forming additives mainly include boron-containing additives, organic pho...

AI Technical Summary

Problems solved by technology

The existing film-forming additives promote the formation of a thick positive electrode surface film, which will lead to an increase in interfacial impedance, and at the same time, there is a problem of instability at higher voltages such as 4.8 V or higher.