Silicon-carbon negative electrode material for lithium ion battery and preparation method thereof

Abstract

The invention discloses a silicon-carbon negative electrode material of a lithium ion battery. The negative electrode material is a composite material prepared from nano silicon particles and porous carbon, and the nano silicon particles are generated by in-situ thermal decomposition of raw material silicon carbide. The invention also provides a preparation method of the silicon-carbon negative electrode material for the lithium ion battery. The preparation method comprises the following steps: paving a layer of carbon black at the bottom of the graphitization furnace core as a heat insulationmaterial; uniformly mixing 10-20 parts of silicon carbide powder with the average particle size of 10-20 [mu]m and 200 parts of a resistance material with the particle size of 8-25 mm, and paving themixture on carbon black; and paving 100 parts of porous carbon material with the average particle size of 16-20 microns and the specific surface area of 50-100 m<2> / g on the silicon carbide / resistance material composite layer. Compared with the prior art, the prepared negative electrode material has the advantages that the first gram capacity is greater than 600 mAh / g, the first coulombic efficiency is greater than 85.4%, and the problem of poor cycle performance of a silicon-based negative electrode material is effectively solved.

Description

technical field [0001] The invention relates to the technical field of electrode materials, in particular to a silicon-carbon negative electrode material for lithium-ion batteries and a preparation method thereof. Background technique [0002] The development of lithium-ion batteries with high energy density and long cycle life is of great significance for applications in portable electronics and electric vehicles. To this end, electrode materials must possess high lithium storage capacity and satisfactory cycle stability. As an alternative material for graphite anodes, silicon has the highest known theoretical specific capacity (4200 mAh / g) and a suitable charge-discharge platform (0.4–0.5 V), and is considered the most promising anode material. However, silicon is completely intercalated to form an alloy Li 22 Si 5 A volume expansion of up to 300% will occur when the electrode is pulverized, separated from the current collector, and the specific capacity is rapidly atte...

AI Technical Summary

Problems solved by technology

However, the preparation process of silicon nanowires, silicon nanotubes, and silicon nanofilms is complex and costly, and is limited to a small amount of synthesis in the laboratory, which cannot meet the needs of industrialization