▎ 摘　　要

NOVELTY - Silicon-carbon composite material comprises at least one positively-charged silicon-carbon layer and at least one negatively-charged silicon-carbon layer which are alternately stacked by layer-by-layer self-assembly. USE - The silicon-carbon composite material is useful for lithium ion battery (claimed). ADVANTAGE - The silicon-carbon composite material is a multilayer nanostructure with precisely controllable composition and thickness, can be tightly combined and uniformly distributed on film, has high specific capacity of silicon materials and excellent conductivity, efficiently alleviates the huge change in the volume of silicon during the charging and discharging process of the lithium-ion battery, and improves the cycle stability of the lithium-ion battery. DETAILED DESCRIPTION - INDEPENDENT CLAIMS are also included for: (1) a method for preparing the silicon-carbon composite material, comprising (i) mixing the mixed powder of silicon material and carbon material with cationic polyelectrolyte and anionic polyelectrolyte to obtain a positively charged silicon carbon layer slurry and a negatively charged silicon carbon layer slurry respectively, and (ii) alternately depositing positively charged silicon-carbon layer slurry and negatively charged silicon-carbon layer slurry on the conductive substrate by layer-by-layer self-assembly to obtain positively charged silicon carbon layer and negatively charged silicon carbon layer alternately, and drying; and (2) a lithium ion battery, whose cathode is mainly prepared from the silicon-carbon composite material.