▎ 摘　　要

NOVELTY - Preparation of composite film electrode involves applying voltage (V1) between working electrode and counter electrode, where graphite foil is working electrode, platinum electrode is counter electrode, and sulfuric acid solution is electrolyte, expanding graphite foil, applying voltage (V2) between working electrode and counter electrode, peeling expanded graphene to obtain graphene flakes, ultrasonically washing and cleaning, drying to obtain electrochemically exfoliated graphene, dissolving potassium permanganate and potassium persulfate in deionized water in weight ratio of 0.75:1.3:15 to obtain mixed solution, placing in PTFE-lined autoclave, hydrothermally reacting, washing product, drying to obtain manganese dioxide nanowires, dispersing electrochemically exfoliated graphene in solvent to obtain graphene solution, dispersing manganese dioxide nanowires in graphene solution to obtain mixed solution, suction filtering to remove solvent to obtain composite membrane, and drying. USE - Preparation of composite film electrode. ADVANTAGE - The method is simple, and provides self-supporting composite film electrode with high yield and mass specific capacitance, and excellent area specific capacitance and cycle stability.