Non-aqueous electrolyte for ternary lithium ion batteries and nickelic lithium ion battery comprising electrolyte

Abstract

The invention relates to the technical field of lithium ion batteries, and discloses non-aqueous electrolyte for ternary lithium ion batteries and a nickelic lithium ion battery comprising the electrolyte. The non-aqueous electrolyte for ternary lithium ion batteries comprises electrolyte lithium salt, a non-aqueous organic solvent and a film-forming additive, wherein the film-forming additive comprises a compound with a structure in formula (I). The additive with the structure in formula (I) is capable of forming uniform and compact protection films on the surfaces of ternary materials, so asto decrease oxidation reaction of the electrolyte on the surfaces of battery materials; the formed SEI films are stable and compact, so that the increase of AC impedance of the batteries in the cycling process is decreased and the cycling performance of the batteries is improved; and the HOMO energy of the films is slightly higher than ethylene carbonate, so that the films can be oxidized and decomposed on the surfaces of anodes in prior to ethylene carbonate, thereby inhibiting the decomposition reaction of the electrolyte solvent and playing a positive role in enhancing the cycling performance of NCM / graphite batteries at a high temperature of 45 DEG C.

Description

technical field [0001] The invention relates to the field of lithium ion batteries, in particular to a non-aqueous electrolyte solution for a ternary lithium ion battery and a high-nickel ternary lithium ion battery containing the electrolyte solution. Background technique [0002] Lithium-ion batteries are widely used in 3C digital products, power tools, electric vehicles and other fields due to their advantages such as high working voltage, high energy density, long life, wide working temperature range and environmental friendliness. Especially in the field of electric vehicles, it has shown explosive growth since 2015. [0003] According to the national "Energy Saving and New Energy Automobile Industry Development Plan", the energy density of power batteries is required to reach more than 300Wh / Kg by 2020. To increase the energy density of lithium-ion batteries, the common measure is to increase the charge cut-off voltage of the battery, but the battery is under high vol...

AI Technical Summary

Problems solved by technology

To increase the energy density of lithium-ion batteries, the common measure is to increase the charge cut-off voltage of the battery, but the battery is under high voltage, and the positive electrode material will have certain defects, such as structural collapse, ion mixing and metal ion dissolution; the second is to use High energy density positive electrode materials, such as NCM622 and NCM811, etc., and high energy density negative electrode materials, such as silicon-based negative electrodes

The increase of Ni content will increase the specific capacity of the ternary material accordingly, bringing higher specific energy, but the increase of Ni content will also lead to the decrease of the stability of the ternary material, and the high nickel ternary material will change from layered to Structural transformation to disordered spinel and rock-salt structures, resulting in an increase in interfacial impedance and a decline in reversible capacity

[0004] The technical difficulty of high-nickel ternary materials lies in the poor high-temperature cycle performance and the problem of high-temperature storage and gas production. Conventional film-forming additives cannot well inhibit the dissolution of metal ions of ternary positive electrode materials, the destruction of the structure, and the oxidation and catalysis of the positive electrode after separation.

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