▎ 摘　　要

NOVELTY - Preparation of graphene-based composite material includes mixing manganese salt, urea and diethylene glycol containing polyvinylpyrrolidone (PVP) to obtain mixed solution, adding the mixed solution into a reaction kettle for hydrothermal reaction, filtering the obtained reaction product, washing, drying and calcining to obtain manganese-based oxide; putting the manganese-based oxide in high temperature reactor for continuously heating, simultaneously, introducing protective gas, and after reaching a first predetermined temperature, introducing first gas containing protective gas and hydrogen into the high temperature reactor, so as to obtain manganese oxide template; and putting the manganese oxide template in high temperature reactor for continuously heating, and simultaneously, introducing the protective gas. USE - The method is for preparation of graphene-based composite material used for preparation of cathode material useful for lithium battery for use in automobile (all claimed). DETAILED DESCRIPTION - Preparation of graphene-based composite material comprises mixing manganese salt, urea and diethylene glycol containing PVP to obtain mixed solution, adding the mixed solution into a reaction kettle for hydrothermal reaction, filtering the obtained reaction product, washing, drying and calcining to obtain manganese-based oxide; putting the manganese-based oxide in high temperature reactor for continuously heating, simultaneously, introducing protective gas, and after reaching a first predetermined temperature, introducing first gas containing protective gas and hydrogen into the high temperature reactor, so as to obtain manganese oxide template; putting the manganese oxide template in high temperature reactor for continuously heating, simultaneously, introducing the protective gas, and after reaching a second predetermined temperature, introducing a second gas containing protective gas and carbon source or protective gas, carbon source and nitrogen source into the high temperature reactor, so as to deposit and form graphene or nitrogen-doped graphene on the manganese oxide template. INDEPENDENT CLAIMS are included for: (1) graphene-based composite material; (2) preparation of cathode material comprising mixing the graphene-based composite material, binder and conductive agent to obtain paste, and coating the paste on copper foil; and (3) cathode material.