▎ 摘　　要

NOVELTY - Preparing silicon-carbon composite material involves mixing the silicon material, carbon material and adhesive agent to obtain intermediate A. The obtained intermediate A is subjected to hot mixing kneading and isostatic pressing to obtain intermediate B. The obtained intermediate B is orderly passes through the first carbonization treatment and coating layer to obtain the intermediate C. The obtained intermediate C is further subjected to second carbonization treatment to obtain silicon-carbon composite material, where the temperature of the second carbonization treatment is not less than the temperature of the first carbonization treatment. USE - Method for preparing silicon-carbon composite material used in lithium ion battery in an electrochemical device (claimed). ADVANTAGE - The method has large tap density and low specific surface area, high conductivity, large specific capacity, excellent capacity, firstly charging and discharging efficiency and cycle performance, in cost-effective manner. DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for the following: 1. Electrochemical device, comprises lithium ion battery, lithium ion capacitor, lithium sulfur battery or all-solid-state battery and silicon-carbon composite material as cathode active material; and 2. Lithium ion battery, comprises cathode, where the cathode comprises the silicon-carbon composite material.