Preparation method of silicon negative electrode of multilevel structure for lithium ion battery

Abstract

The invention belongs to the technical field of lithium ion batteries and particularly relates to a preparation method of a silicon negative electrode of a multilevel structure for a lithium ion battery, which comprises the following steps: micron silicon particles and sublimed sulfur are ground, uniformly mixed and then are placed in a tubular furnace to be subjected to heat treatment, and a layer of sulfur is uniformly coated on the surface of the silicon particles; the silicon particles with dopamine and ferric salt are added into a buffer solution together, the dopamine is polymerized on the surfaces of the composite powder particles under the condition of sufficient stirring, and iron ions are carried; the solid and the graphene oxide obtained after separation are prepared through a hydrothermal reduction method to obtain composite gel; after being washed and dried, high-temperature heat treatment is carried out on the composite gel in the tubular furnace; the composite gel is soaked and washed with diluted hydrochloric acid, and dried to obtain the graphene / silicon composite material. According to the preparation method in the invention, the first coulombic efficiency of theelectrode material is improved by designing an egg yolk shell structure, and the cycling stability is improved; meanwhile, the density of the egg yolk shell structure is realized by utilizing a graphene three-dimensional assembly; and finally, the silicon negative electrode of the multilevel structure for the lithium ion battery is obtained.

Description

technical field [0001] The invention belongs to the technical field of lithium ion batteries, and in particular relates to a preparation method of a silicon negative electrode for lithium ion batteries with a multi-level structure. Background technique [0002] As the most potential anode material for next-generation high-energy-density lithium-ion batteries, silicon is abundant in reserves and has a mass-specific capacity ten times that of graphite. At present, the research of silicon negative electrode is in mass specific capacity (>1000mAhg –1 ), as well as cycle performance (>500 cycles), rate performance research has made great progress. However, the improvement of the above performance is often achieved by reducing the size of the silicon active particles, that is, using nano-silicon as the active material to construct the negative electrode material. Nanotechnology has received extensive attention in silicon anodes and has achieved excellent research results, ...

AI Technical Summary

Problems solved by technology

Nanotechnology has received extensive attention in silicon anodes and has achieved excellent research results, but the application of nanotechnology in silicon anodes will lead to the following problems: 1) The specific surface area is large, resulting in a large consumption of limited lithium sources

However, silicon active particles with a size in the micron range generally suffer from fragmentation and pulverization during charge and discharge, which severely restricts their cycle stability.

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