▎ 摘　　要

NOVELTY - Preparation of graphene/manganese dioxide electrode involves mixing manganese sulfate, phosphorus pentoxide, ferric chloride, sodium nitrate and graphite to obtain mixture, mixing the mixture with concentrated sulfuric acid to obtain mixed solution, reacting to obtain pre-oxidized graphite suspension, placing in an ice-water bath at below 10 degrees C, adding potassium permanganate and potassium manganate, reacting the reactant at 180-220 degrees C for 5-10 hours, adding deionized water, reacting for 15-60 minutes to obtain reaction solution, filtering, washing with hydrochloric acid mixture and deionized water to obtain solid, thermally processing the dried solid to obtain graphene/manganese dioxide composite solid powder, mixing with polyvinylidene fluoride, adding N-methylpyrrolidone to the mixture, stirring to form suspension, soaking foamed nickel in the suspension for 20-40 hours, cooling to obtain foamed nickel electrode and immersing the foamed nickel electrode in sodium sulfate solution. USE - The method is useful for preparation of graphene/manganese dioxide electrode, which is useful for supercapacitor. ADVANTAGE - The method enables preparation of graphene/manganese dioxide electrode with high capacitance. The graphene/manganese dioxide electrode does not contain template and other surfactant. DETAILED DESCRIPTION - Preparation of graphene/manganese dioxide electrode involves mixing manganese sulfate, phosphorus pentoxide, ferric chloride, sodium nitrate and graphite in a mass ratio of 1:1:1:0.5:1 to obtain mixture, mixing the mixture with 95-98% concentrated sulfuric acid at 70-90 degrees C to obtain mixed solution, magnetically stirring, reacting for 20-60 minutes to obtain pre-oxidized graphite suspension, placing the pre-oxidized graphite suspension in an ice-water bath at below 10 degrees C, magnetically stirring, adding potassium permanganate and potassium manganate, completely dissolving the solid, removing the ice-water bath to obtain reactant, reacting the reactant at 180-220 degrees C for 5-10 hours, cooling to room temperature, heating at 60-90 degrees C, adding deionized water, magnetically stirring, reacting for 15-60 minutes to obtain reaction solution, filtering the reaction solution, washing with hydrochloric acid mixture and deionized water to obtain solid, drying the solid at 80-120 degrees C for 1-3 hours, thermally processing the dried solid at 350-450 degrees C for 6-10 hours under argon atmosphere to obtain graphene/manganese dioxide composite solid powder, uniformly loading manganese dioxide nanoparticles on graphene layers, cooling the graphene/manganese dioxide composite solid powder to room temperature, mixing with polyvinylidene fluoride in a mass ratio of 95:5 to obtain mixture, adding N-methylpyrrolidone to the mixture, stirring at 50-70 rpm to form suspension, soaking foamed nickel in the suspension for 20-40 hours, taking the foamed nickel from the liquid, drying in a vacuum furnace at 80-100 degrees C for 5-10 hours, cooling to room temperature under vacuum to obtain foamed nickel electrode and immersing the foamed nickel electrode in 1 mol/l sodium sulfate solution for 20-40 hours. The amount of concentrated sulfuric acid is 10-30 times the mass of graphite. The amount of potassium permanganate is 15-30 times the mass of graphite. The amount of potassium manganate is 5-10 times the mass of graphite. The amount of deionized water is 200-300 times the mass of graphite. The graphene/manganese dioxide composite is composite of graphene and manganese dioxide nanoparticles with diameter of 10-20 nm. The amount of N-methylpyrrolidone is 200-300 times the mass of the graphene/manganese dioxide composite solid powder.