Anti-overcharging additive used for lithium battery electrolyte, and lithium battery electrolyte comprising additive

Abstract

The invention provides an anti-overcharging additive used for a lithium battery electrolyte, and the lithium battery electrolyte comprising the additive, and relates to the technical field of the lithium ion battery. The anti-overcharging additive mainly consists of biphenyl, phenylcyclohexane, diflurodiphenyl, fluorobenzene and lithium difluorophosphate, wherein the biphenyl, phenylcyclohexane and diflurodiphenyl are used as electrical polymerization type compounds, so that a cell can have corresponding over-charging additives for reaction in different voltage sections in an over-charging process constantly; meanwhile, by virtue of interaction of fluorobenzene and phenylcyclohexane, the electrical polymerization film forming impedance degree of phenylcyclohexane in a low voltage section can be lowered; by adding lithium difluorophosphate, increasing of impedance caused by voltage section micro film forming in normal use of the cell due to addition of the over-charging additives of biphenyl, phenylcyclohexane, diflurodiphenyl, fluorobenzene, and the like can be lowered; and furthermore, the lithium battery electrolyte comprising the anti-overcharging additive can block thermal breakdown possibly caused by overcharging in a mild manner, so that performance degradation of the cell in the overcharging condition can be further avoided.

Description

technical field [0001] The invention relates to the technical field of lithium ion batteries, in particular to an anti-overcharge additive for lithium battery electrolyte and a lithium battery electrolyte containing the same. Background technique [0002] With the continuous development of lithium-ion battery demand, designers continue to increase the charge cut-off voltage of the battery cell, or change the structure of the material (such as the continuous development of ternary cathode materials towards high nickel), in order to achieve higher energy density requirements. Increasing the charging cut-off voltage or changing the material ratio will inevitably reduce the thermal stability of the battery material. [0003] The overcharge test is intended to simulate the overcharging of the battery cell that may be caused by the failure of the charger, protection board and other components. This test has always been difficult for lithium-ion battery testing, especially for the ...

AI Technical Summary

Problems solved by technology

In this way, the strong oxidation-reduction reaction inside the battery releases a large amount of heat, coupled with the Joule heat generated by the battery itself during the charging process, causing the temperature of the battery core to rise sharply, causing the SEI film to decompose, the separator to melt, and an internal short circuit to occur, and the electrolyte to decompose And so on a series of reactions, thus triggering the thermal failure of the cell