Lithium ion battery negative plate and preparation method thereof

Abstract

The invention discloses a lithium ion battery negative plate and a preparation method thereof, the lithium ion battery negative plate comprises a current collector and a coating structure at least arranged on one side of the current collector, the coating structure comprises a graphite buffer layer and a silicon carbon layer, and the graphite buffer layer is located between the current collector and the silicon carbon layer; the graphite buffer layer is prepared from graphite-containing slurry, graphite in the graphite-containing slurry is carbon microsphere graphite, the silicon-carbon layer is prepared from silicon-carbon-containing slurry, and the silicon-carbon-containing slurry also contains pre-lithiated CMC (Carboxy Methylated Cellulose). The preparation method comprises the following steps: coating the surface of the current collector with slurry containing graphite, rolling for the first time to obtain the current collector containing the graphite buffer layer, coating the surface of the current collector containing the graphite buffer layer with slurry containing silicon and carbon, and rolling for the second time to obtain the lithium ion battery negative plate. The lithium ion battery negative electrode plate with excellent first efficiency and coating adhesive power is finally obtained by the method disclosed by the invention.

Description

technical field [0001] The invention relates to a lithium ion battery negative electrode sheet for improving the primary efficiency and coating adhesion of a silicon carbon composite material and a preparation method thereof, and belongs to the technical field of lithium ion batteries. Background technique [0002] The energy crisis is one of the most important problems facing human society at present, and the collection, storage and transportation of new clean energy has attracted the attention of the whole society. As an important medium for electrical energy conversion and storage, lithium-ion batteries have the advantages of high energy density, good cycle stability, wide operating potential window, high safety, and environmental friendliness. They are widely used in portable electronic products, large-scale energy storage and electric vehicles. and other fields. With the rapid development of new energy vehicles, the increase in cruising range places higher requirements...

AI Technical Summary

Problems solved by technology

However, there is a large volume change (300%) during the silicon de / intercalation process, which can easily lead to particle pulverization and then fall off from the current collector.

At the same time, the SEI film on the surface of the silicon negative electrode is constantly broken and formed during the charging and discharging process, which continuously consumes active lithium ions, resulting in a decrease in Coulombic efficiency and battery cycle life.

However, simply increasing the silicon content in the silicon carbon anode will lead to problems such as low Coulombic efficiency, large volume change, and poor cycle stability.

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