▎ 摘　　要

NOVELTY - Preparation of graphene ink involves preparing a persulfate electrolyte aqueous solution, preparing electrochemical stripping electrode using a graphite foil as an oxidizing electrode for stripping in a persulfate electrolyte aqueous solution, applying a constant voltage or a constant current to the stripping electrode in aqueous solution, separating the graphene nanofiltration membrane from solution by filtration, ultrasonically dispersing in an organic solvent without performing centrifugation and precipitation, and producing graphene ink having high concentration of 20 mg/mL or more. USE - Preparation of graphene ink for producing graphene-coated metal material (all claimed). ADVANTAGE - The graphene ink enables formation of graphene-coated metal material quickly and efficiently. DETAILED DESCRIPTION - Preparation of graphene ink involves preparing a persulfate electrolyte aqueous solution, preparing electrochemical stripping electrode using a graphite foil as an oxidizing electrode for stripping in a persulfate electrolyte aqueous solution and using a metallic foil or metal net in the form of a columnar or polygonal column as a reducing electrode for stripping, applying a constant voltage or a constant current to the stripping electrode in aqueous solution to electrochemically peel off the single or multi-layer graphene nanofibers from the oxidized electrode, separating the graphene nanofiltration membrane from solution by washing the peeled membrane by filtration, ultrasonically dispersing in an organic solvent without performing centrifugation and precipitation, and producing graphene ink having high concentration of 20 mg/mL or more. INDEPENDENT CLAIMS are included for the following: (1) graphene ink; (2) preparation of metal-coating graphene ink; (3) coating method of metal surface with graphene ink; and (4) graphene-coated metal material.