▎ 摘　　要

NOVELTY - Cathode material comprises a silicon composite substrate with DV50 range of 2.5-15 m, and particle size distribution is 0.1-10 Dn/Dv50 is 0.6. The silicon composite substrate includes nano silicon grains, silicon oxide or silicon dioxide. The cathode material further includes an oxide MeOy layer which covers at least a part of the silicon composite substrate, and the oxide MeOy layer includes a carbon material. The cathode material further includes a polymer layer covering at least a part of oxide MeOy layer, and contains carbon material. The polymer layer comprises polyvinylidene fluoride, carboxymethyl cellulose, sodium carboxymethyl cellulose, polyvinylpyrrolidone, polyacrylic acid and its derivatives, polystyrene butadiene rubber, polyacrylamide, polyimide or polyamideimide. The carbon material comprises carbon nanotubes, carbon nanoparticles, carbon fibers or graphene. USE - The cathode material is useful in cathode for an electrochemical device, preferably lithium ion battery of electronic device (all claimed), preferably a notebook computer, a pen input type computer, a mobile computer, an electronic book player, a portable telephone, a portable fax machine, a portable copier, a portable printer, a head stereo headphone, a video recorder, a liquid crystal television, a portable cleaner, a portable CD machine, a mini optical disc, a transceiver, an electronic notepad; calculator, memory card, portable recorder, radio, standby power supply, motor, automobile, motorcycle, power-assisted bicycle, bicycle, lighting device, toy, game machine, clock, electric tool, flash lamp, camera, household large storage battery or lithium ion capacitor. ADVANTAGE - The cathode material has good cycle performance, good multiplying power performance and low expansion rate, and has good rate capability and low expansion rate in lithium ion battery having high energy density, high safety, no memory effect and long working life. DETAILED DESCRIPTION - Cathode material comprises a silicon composite substrate with DV50 range of 2.5-15 m, and particle size distribution is 0.1-10 Dn/Dv50 is 0.6. The silicon composite substrate includes nano silicon grains, silicon oxide or silicon dioxide. The cathode material further includes an oxide MeOy layer which covers at least a part of the silicon composite substrate, and the oxide MeOy layer includes a carbon material. The cathode material further includes a polymer layer covering at least a part of oxide MeOy layer, and contains carbon material. The polymer layer comprises polyvinylidene fluoride, carboxymethyl cellulose, sodium carboxymethyl cellulose, polyvinylpyrrolidone, polyacrylic acid and its derivatives, polystyrene butadiene rubber, polyacrylamide, polyimide or polyamideimide. The carbon material comprises carbon nanotubes, carbon nanoparticles, carbon fibers or graphene. Me = Al, Si, Ti, Mn, V, Cr, Co or Zr; and y = 0.5-3.