▎ 摘　　要

NOVELTY - Preparing carbon-silicon carbide-silicon composite cathode material comprises (1) placing silicon nitride and carbon source in the ball milling tank, adding dispersion medium, and processing at 200-500 revolutions/minute for 3-10 hours to obtain mixed slurry of silicon nitride and carbon source, (2) placing the composite powder of silicon nitride and carbon source into high-temperature furnace, heat treating at 500-800℃ for 3-10 hours to carbonize the organic carbon source in situ under argon or nitrogen atmosphere, connecting with inorganic carbon source to form complete coating on silicon nitride, and obtaining carbon-silicon nitride composite powder, and (3) placing the carbon-silicon nitride composite powder into vacuum furnace, heat-treating at 800-1500℃ for 0.5-10 hours under vacuum of 10-4-100 Pa, decomposing silicon nitride to form dispersed silicon particles, and reacting silicon with carbon cladding to form silicon carbide. USE - The material is useful for lithium-ion batteries (claimed). ADVANTAGE - The material: has hollow structure; disperses nanoporous silicon particles inside; disperses columnar silicon carbide fibers in the middle; uniformly coats carbon on the surface of the particles; can alleviate the volume expansion generated during the charging and discharging process; and prevents the falling off of silicon particles, so it has excellent electrochemical performance. The method: has simple technological process, cheap and easily obtaining raw material and easy industrial production; and is economical. DETAILED DESCRIPTION - Preparing carbon-silicon carbide-silicon composite cathode material comprises (1) placing silicon nitride and carbon source in the ball milling tank, adding dispersion medium, and processing at 200-500 revolutions/minute for 3-10 hours to obtain mixed slurry of silicon nitride and carbon source, where the mass ratio of silicon nitride powder, carbon source and dispersion medium is 10-30:20-40:20-40, the mass ratio of organic carbon source and inorganic carbon source in carbon source is 1:0.1-2, placing the slurry into oven and drying it at 80-150℃ for 10-24 hours to obtain composite powder of silicon nitride and carbon source, where the silicon nitride powder is α phase with particle size of 50-500 nm, the carbon source is organic carbon source and inorganic carbon source, the organic carbon source is resin, pitch, starch, glucose, dextrin, sucrose, citric acid, polythiophene, polypyrrole and/or polyaniline, the inorganic carbon source is acetylene black, carbon black, carbon nanotubes, carbon fibers and/or graphene, and the dispersion medium is absolute ethanol or deionized water, (2) placing the composite powder of silicon nitride and carbon source into high-temperature furnace, heat treating at 500-800℃ for 3-10 hours to carbonize the organic carbon source in situ under argon or nitrogen atmosphere, connecting with inorganic carbon source to form complete coating on silicon nitride, and obtaining carbon-silicon nitride composite powder, and (3) placing the carbon-silicon nitride composite powder into vacuum furnace, heat-treating at 800-1500℃ for 0.5-10 hours under vacuum of 10-4-100 Pa, decomposing silicon nitride to form dispersed silicon particles, and reacting silicon with carbon cladding to form silicon carbide, i.e. obtaining carbon-silicon carbide-silicon composite cathode material for lithium-ion batteries.