Silicon-carbon negative electrode material and preparation method thereof

Abstract

The invention discloses a silicon-carbon negative electrode material with a stable structure and good cycle performance and a preparation method of the silicon-carbon negative electrode material. The stable structure specifically refers to the stable internal structure of silicon nanoparticles and the stable structure of silicon-carbon particles formed by compounding the silicon nanoparticles, carbon nanotubes, graphite nanosheets and amorphous carbon. The silicon nanoparticles are high in amorphization degree and small in grain size, and the interior of the silicon nanoparticles is of a structure in which nanocrystals are uniformly embedded in an amorphous state. According to the silicon-carbon composite particles, a multi-layer frame structure is built through the graphite nanosheets, the multi-layer frame structure and the uniformly dispersed carbon nanotubes form a supporting structure; the silicon nanoparticles are in close contact with the carbon nanotubes and the graphite nanosheets to form dense composite particles; and the outer layers of the composite particles are coated with a layer of dense amorphous carbon material. The silicon-carbon negative electrode material is small in specific surface area (less than 4m < 2 >/g), high in compaction density, high in specific capacity and good in cycle performance (the capacity retention rate is as high as 86% after a whole battery undergoes 900 cycles at normal temperature).

Description

technical field [0001] The invention relates to the technical field of lithium-ion batteries, in particular to a silicon-carbon negative electrode material with stable structure and good cycle performance and a preparation method thereof. Background technique [0002] In order to meet the increasing demand for electricity, the development of anode materials with higher energy density has always been a research hotspot [1-3]. The theoretical specific capacity of silicon is more than 11 times that of commercial graphite anodes, the lithium intercalation potential is higher than that of graphite, it is more difficult to form lithium dendrites and is rich in resources, and it is environmentally friendly. Therefore, silicon-based anode materials are considered to be the most promising to replace graphite anodes A new generation of high energy density anode materials [4-7]. However, the volume effect and low conductivity of silicon materials seriously inhibit its wide application...

AI Technical Summary

Problems solved by technology

[0008] The technical problems to be solved by the present invention are problems such as uneven dispersion of silicon nanoparticles in silicon-carbon composite materials, poor electrical conductivity, large expansion of silicon nanomaterials, and inability to be industrialized.

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