▎ 摘　　要

NOVELTY - Capacitor is claimed. The capacitor is prepared by (i) heat-treating the industrial waste carbon material at 800-2300 degrees C, electrolyzing the industrial carbon waste material to obtain graphene carbon dots, where the electrochemical method uses a voltage of 1V-50V, where the electrolyte concentration is 0.01-30 mol/l, and the electrolysis time is 1-24 hours, and (ii) mixing the obtained graphene carbon dots with graphene and carrying out reduction, where the graphene carbon dot is added in an amount of 1-5%. USE - The method is useful for preparing the capacitor. ADVANTAGE - The method: directly achieve nitrogen doping, improves the problems of low mass specific capacity and rate performance improvement of traditional graphene supercapacitors.