Negative pole piece capable of improving cycle performance of high-voltage lithium battery and preparation method and application thereof

Abstract

The invention relates to the technical field of lithium ion batteries, in particular to a negative pole piece capable of improving the cycle performance of a high-voltage lithium battery and a preparation method and application thereof. The preparation method comprises the following steps: step 1, coating a coating A on a long paste surface of a negative current collector, wherein slurry of the coating A comprises the following components in percentage by mass: 77.2%-97.01% of a silicon-carbon negative electrode, 0.48%-19.5% of artificial graphite, 0.5%-1.0% of a conductive agent and 1.5%-3.0% of a binder; and step 2, coating a coating B on a short paste surface of the negative electrode current collector, wherein slurry of the coating B comprises the following components in percentage by mass: 77.2%-97.01% of a silicon-carbon negative electrode, 0.48%-19.5% of artificial graphite, 0.5%-1.0% of a conductive agent and 1.5%-3.0% of a binder. Through a negative electrode double-layer coating mode, the long paste surface of the negative electrode current collector is coated with the coating A, and the short paste surface of the negative electrode current collector is coated with the coating B, so that the overpotential distribution of high-voltage lithium cobalt oxide on the long paste surface of the current collector and the diffusion impedance between the long paste surfaces of the positive electrode and the negative electrode are improved, the polarization of the high-voltage lithium cobalt oxide in the circulation process is reduced, and the lithium precipitation phenomenon and the capacity retention ratio of the high-voltage lithium cobalt oxide in the circulating process are improved.

Description

technical field [0001] The invention relates to the technical field of lithium-ion batteries, in particular to a negative pole piece for improving the cycle performance of a high-voltage lithium battery, a preparation method and an application thereof. Background technique [0002] With the development of multi-function and miniaturization of electrical equipment, various portable devices such as smartphones, tablet computers, and notebook computers have put forward higher requirements for lithium-ion batteries with small size and long standby time. Especially with the birth of 5G mobile phones, the requirements for the battery life and volume of lithium-ion batteries have been further increased, and there is an urgent need to increase the volumetric energy density of batteries. In addition, lithium-ion batteries with lighter weight, smaller size, higher output voltage and higher power density are also being developed in other electrical equipment, such as energy storage equ...

AI Technical Summary

Problems solved by technology

Lithium-ion batteries with higher operating voltage will be more popular in the market, such as 4.4V mobile phones of Xiaomi mobile phones and Huawei mobile phones, but it is difficult to meet the increasing demands of people and needs to be further improved.

However, with the increase of working voltage, the high-voltage lithium cobalt oxide material is highly polarized during the cycle, and is prone to lithium precipitation and capacity fading. The cycle life is short, which limits its wide application.

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