Application of borate compound serving as additive for high-voltage lithium-ion battery electrolyte

Abstract

The invention belongs to the field of lithium-ion batteries, and particularly relates to an application of a borate compound serving as an additive for high-voltage lithium-ion battery electrolyte. The borate compound is in a structure as described in formula 1. The invention also discloses the high-voltage lithium-ion battery electrolyte which is obtained by adopting a means of adding the functional additive into common electrolyte, wherein the weight of the added functional additive accounts for 0.1%-5% that of the common electrolyte; the common electrolyte consists of a cyclic carbonate solvent, a liner carbonate solvent and conductive lithium salt; the functional additive is the borate compound. By virtue of the added additive, on one hand, the interface of a positive electrode / the electrolyte is optimized, the surface activity of the positive electrode is lowered and the oxygenolysis of the electrolyte is inhibited; on the other hand, due to the introduction of boron, the safety of the electrolyte is enhanced remarkably. By virtue of the high-voltage lithium-ion battery electrolyte, the safety performance and the cycling performance of a high-voltage (3-4.9Vvs.Li / Li<+>) lithium battery can be enhanced.

Description

technical field [0001] The invention belongs to the field of lithium-ion batteries, and specifically relates to the application of a boric acid ester compound as an electrolyte additive for a high-voltage lithium-ion battery. Background technique [0002] At present, with the popularization of portable electronic devices, the development of electric tools and electric vehicles in recent years, lithium-ion batteries as a new generation of high-energy power sources have received extensive attention. At present, the positive electrode materials of commercial lithium-ion batteries mainly include lithium manganese oxide, lithium cobalt oxide, ternary materials, and lithium iron phosphate. The charging cut-off voltage generally does not exceed 4.2V. With the advancement of technology and the continuous development of the market, it is increasingly important and urgent to increase the energy density of lithium batteries. Therefore, increasing the operating voltage of lithium-ion b...

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Problems solved by technology

[0004] However, while increasing the voltage of the positive electrode material, the electrical properties of the battery such as charge and discharge cycles are declining. On the one hand, the reason is that the structure of the newly developed positive electrode material is not stable enough, and on the other hand, it is the matching problem of the electrolyte.

Conventional commercial electrolytes are easy to oxidize and decompose on the surface of the positive electrode of the battery when the voltage is higher than 4.5V. The oxidative decomposition reaction of the electrolyte itself will also cause the positive electrode material to change in shape and structure collapse.

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