▎ 摘　　要

NOVELTY - Preparing three-dimensional graphene-C3N4 composite material comprises mixing the graphene oxide dispersion with dicyandiamide to obtain a mixed solution; freeze-drying the mixed solution to obtain a solid precursor powder in an argon atmosphere, and calcining the solid precursor powder. USE - The material is used as a lithium metal cathode (claimed). ADVANTAGE - The material improves stability; ensures rapid passage of Lithium ions, and can be used as an synthetic SEI layer with excellent performance to improve lithium interface stability of the metal anode improves the electrochemical performance. DETAILED DESCRIPTION - INDEPENDENT CLAIMs are also included for: (1) three-dimensional graphene-C3N4 composite material prepared by the preparation method, comprising a graphene framework and a C3N4 layer, and the C3N4 layer is supported on the surface of the graphene framework; and (2) a half-cell, comprising Clgard-2400 separator, a three-dimensional graphene-C3N4 composite material prepared by the preparation method or the three-dimensional graphene of material s used as the lithium metal cathode, the electrolyte is LiTFSI solution, the solvent of the LiTFSI solution includes 1,3 dioxolane and ethylene glycol dimethyl ether, the 1,3 dioxolane and ethylene glycol volume ratio of dimethyl ether is 1:1.