▎ 摘　　要

NOVELTY - Preparation of graphene-based composite, involves adding 98 %mass concentrated sulfuric acid, graphite powder and sodium nitrate in reactor, placing in ice water bath, adding potassium permanganate, heating and stirring, adding water, raising temperature and adding water, adding 30 %mass hydrogen peroxide solution and stirring, suction filtering, washing with 5 %mass hydrochloric acid and water until sulfate radical is completely removed, drying to obtain solid graphite oxide, dispersing in water to obtain 0.1-2 mg/mL suspension (A), ultrasonically peeling, centrifuging and washing to remove lower precipitate and obtain upper layer graphene oxide suspension (B), dissolving potassium permanganate in suspension (B), adding polyethylene glycol, transferring the obtained mixed solution (M1) to a PTFE-lined sealed stainless-steel reactor in constant temperature box, reacting, cooling, filtering, washing with anhydrous ethanol and water, and freeze-drying. USE - Preparation of graphene-based composite for supercapacitor. ADVANTAGE - The method is simple, convenient, economical and rapid, does not require surfactant, template agent, and stabilizer, and has convenient post-processing. The composite has excellent electrochemical stability and higher specific surface area which solves the problem of agglomeration and improves electrochemical performance of trivalent manganese. DETAILED DESCRIPTION - Preparation of graphene-based composite, involves (S1) orderly adding 98 %mass concentrated sulfuric acid, graphite powder and sodium nitrate in mass-volume ratio of 23 mL: 1 g: 1.2 g in reactor, placing in ice water bath, adding potassium permanganate, where ratio of potassium permanganate and graphite powder is 3:1, controlling temperature at 6degrees Celsius for 30 minutes, raising temperature to 35degrees Celsius, and stirring for 2 hours, adding water, where ratio of water and concentrated sulfuric acid is 23:200, raising temperature to 90degrees Celsius, continuously stirring for 30 minutes, continuously adding water, where the volume ratio of added water and concentrated sulfuric acid is 23:450, adding 30 %mass hydrogen peroxide solution and stirring, where the volume ratio of hydrogen peroxide solution and concentrated sulfuric acid is 23:6, suction filtering, repeatedly washing with 5 %mass hydrochloric acid and water until sulfate radical is completely removed, drying solid in dryer to obtain solid graphite oxide, (S2) dispersing in water to obtain 0.1-2 mg/mL suspension (A), ultrasonically peeling for 90 minutes, centrifuging and washing to remove lower precipitate to obtain upper layer graphene oxide suspension (B), (S3) dissolving potassium permanganate in suspension (B), adding polyethylene glycol, where ratio of potassium permanganate and polyethylene glycol is 20 mg: 1 mL, and volume ratio of suspension (B) and polyethylene glycol is (5:1)-(10:1), transferring obtained mixed solution (M1) in PTFE-lined sealed stainless steel reactor, reacting in constant temperature box at 150-180degrees Celsius for 10-12 hours, completing reaction, cooling to room temperature, filtering, washing with anhydrous ethanol and water, and freeze-drying to obtain manganite-graphene composite.