Lithium ion battery composite negative electrode material and preparation method thereof

Abstract

The invention provides a lithium ion battery composite negative electrode material, which comprises a fixed material, a first coating layer and a second coating layer, wherein the first coating layerand the second coating layer sequentially coat the mixed material; the mixed material is a mixed material of a silicon-based material, graphene and graphite; the mass ratio of the silicon-based material to the graphite is 1:(1 to 10); the mass ratio of the graphite to the graphene is 100:(0.01 to 5); the first coating layer is polyaniline; the second coating layer is polypyrrole. The invention also provides a preparation method of the lithium ion battery composite negative electrode material. The lithium ion battery composite negative electrode material and the preparation method provided by the invention have the advantages that the conductive performance of the composite negative electrode material is improved; the volume expansion of the silicon-based material is relieved; the double-layer conduction polymers have good compactness; the contact between electrolyte and the silicon-based material is effectively isolated; the circulation performance is excellent; in addition, the energyconsumption is reduced; the process is simple; the operation and the industrialization are easy.

Description

【Technical field】 [0001] The invention relates to the technical field of battery materials, in particular to a lithium-ion battery composite negative electrode material and a preparation method thereof. 【Background technique】 [0002] Lithium-ion batteries are widely used in various power tools due to their high energy density and long life. At present, the commonly used anode materials for lithium-ion batteries are graphite-based carbon materials, which have low potential for lithium deintercalation, suitable reversible capacity, high initial efficiency and cycle stability, and are rich in resources and low in price. Low cost and other advantages; however, the theoretical specific capacity of graphite is low, about 372mAh / g, making lithium-ion batteries with graphite as the negative electrode unable to meet people's increasing requirements for energy density. [0003] Silicon-based materials have a high theoretical specific capacity (about 4200mAh / g), abundant reserves and...

AI Technical Summary

Problems solved by technology

At present, the commonly used anode materials for lithium-ion batteries are graphite-based carbon materials, which have low potential for lithium deintercalation, suitable reversible capacity, high initial efficiency and cycle stability, and are rich in resources and low in price. Low cost and other advantages; however, the theoretical specific capacity of graphite is low, about 372mAh / g, making lithium-ion batteries with graphite as the negative electrode unable to meet people's increasing requirements for energy density

[0003] Silicon-based materials have a high theoretical specific capacity (about 4200mAh / g), abundant reserves and low price; however, silicon will produce a volume change of about 300% during the intercalation / delithiation process, and the huge volume change causes electrode The powdering and exfoliation of the material makes the connection between silicon particles and the particles and the current collector worse, and the electrical contact is lost, resulting in a rapid decline in capacity.

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