▎ 摘　　要

NOVELTY - A silicon carbon cathode material comprises 40-70 wt.%, preferably 50-60 wt.% nano-silicon and oxide layer on surface of nano-silicon, 1-30 wt.%, preferably 10-20 wt.% multilayer graphene sheet, and 10-40 wt.%, preferably 20-30 wt.% amorphous carbon. USE - The silicon carbon cathode material is used for lithium ion battery (claimed). ADVANTAGE - The cathode material has small volume expansion effect and good cycle performance and is cheap and suitable for mass production. DETAILED DESCRIPTION - An INDEPENDENT CLAIM is included for preparation of the cathode material comprising: (A) coarsely crushing silicon raw material to obtain silicon powder with median particle diameter D50 of 1-20 mu m, adding into dispersing tank of primary sand mill, adding organic solvent to adjust the solid content to 10-40 wt.%, and primary grinding at speed of 13-16 m/second for 10-50 hours until maximum particle diameter D100 is less than 800 nm; (B) secondary grinding at speed of 14-17 m/second for 10-50 hours with ball milling bead, where mass ratio of ball milling bead and silicon powder is (15-20):1 to obtain nano-silicon with median particle diameter D50 less than 95 nm and maximum particle diameter D100 of less than 250 nm, where organic solvent for wet grinding is methanol, toluene, benzyl alcohol, ethanol, ethylene glycol, ethanol chloride, propanol, isopropanol, propylene glycol, butanol, n-butanol, isobutanol, pentanol, neopentyl alcohol, octanol, acetone, and/or cyclohexanone and ball milling beads are stainless steel, agate, ceramic, zirconia, alumina, cemented carbide, or zirconium silicate; (C) taking multi-layer graphene sheet and nano-silicon slurry, ultrasonically vibrating at more than 20000 Hz for more than 0.5 hour and high speed dispersing at more than 2000 rpm for more than 1 hour; and (D) putting in gas phase deposition furnace, introducing inert gas until oxygen content is less than 100 ppm, raising temperature to 500-800, introducing amorphous carbon, and vapor depositing for 1-4 hours, where inert gas is nitrogen, argon gas or neon gas.