High-voltage lithium ion battery electrolyte additive and electrolyte

Abstract

The invention provides a novel high-voltage lithium ion battery electrolyte, which comprises a non-aqueous organic solvent, a lithium salt and an electrolyte additive, and is applied to a lithium ionbattery with the highest working voltage of 4.35-4.8 V, wherein the electrolyte additive is an alkyl-bis(trimethylsilyl) phosphite compound. In the first-cycle charging process of the battery, the electrolyte additive participates in formation of a positive electrode interface passive film containing a P-O-Si bond, direct contact between the electrolyte and the surface of the positive electrode isblocked, side reaction between the cathode and the electrolyte is reduced, the effect of protecting the cathode is achieved, the interface performance of the positive electrode material is improved,the internal resistance of the battery is effectively reduced, capacity reduction is inhibited, and the high-voltage cycle performance of the lithium ion battery can be effectively improved.

Description

technical field [0001] The invention belongs to the field of lithium-ion batteries, and in particular relates to a high-voltage lithium-ion battery additive and an electrolyte thereof. Background technique [0002] Lithium-ion batteries are widely favored due to their advantages such as high energy density, high operating voltage, no memory effect, long cycle life and low self-discharge. After years of development, small-capacity lithium-ion batteries have been widely used in portable electronic devices such as mobile phones, notebook computers, and digital cameras. With the promotion of electric vehicles and other equipment, the demand for lithium-ion batteries with high energy density is becoming more and more urgent. by the energy formula It can be seen that increasing the operating voltage of lithium-ion batteries can effectively increase the energy density. At present, the voltage range used by lithium-ion batteries is mainly 3.0-4.35V. While increasing the working ...

AI Technical Summary

Problems solved by technology

However, under high pressure, due to the increase in the reactivity of the cathode material, the electrolyte is prone to oxidation reaction, which destroys the charge-discharge chemical system in the battery, resulting in a rapid decline in the capacity of the lithium-ion battery under high-voltage conditions, which seriously shortens the battery life.

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