▎ 摘　　要

NOVELTY - Preparation of three-dimensional graphene-based nitrogen-doped carbon layer composite material involves dehydrating graphene oxide raw material, dissolving in N-methylpyrrolidone solvent, adding phthalic anhydride and 2,6-diaminoanthraquinone to the graphene oxide solution, reacting phthalic anhydride and 2,6-diaminoanthraquinone in a N-methylpyrrolidone solution of graphene, polymerizing polyimide layer on the graphene framework through solvothermal method, and carbonizing carbon dioxide under nitrogen atmosphere. USE - Preparation of graphene-based nitrogen-doped carbon layer composite material used as cathode of sodium ion battery (all claimed). ADVANTAGE - The method is simple, economical and has mild reaction conditions, and provides composite material having excellent electrochemical performance. DETAILED DESCRIPTION - An INDEPENDENT CLAIM is included for usage method of composite material, which involves assembling composite material into a lithium ion button-type semi-battery as a cathode material of sodium ion battery, uniformly mixing composite material, carbon black super-P and polyvinylidene fluoride in a weight ratio of 7:2:1, and uniformly coating mixture on a pure copper foil to prepare an anode.