▎ 摘　　要

Graphene and N-doped graphene were synthesized by a solvothermal process, and their composites with SnO2 nanoparticles were prepared by a facile one-pot chemical solution method. The corresponding films were fabricated by a blade coating process and followed by heat treatment at 400 degrees C for 1 h. All-solid-state supercapacitors were fabricated with graphene based films and a polymer gel of polyvinyl alcohol/H3PO4 as electrodes and electrolyte, respectively. The capacitance performance of the as-fabricated supercapacitors was characterized. The results suggest that compared with graphene, N-doped graphene exhibits larger crystalline size, lower specific surface area, yet superior capacitance performance, and the incorporation of SnO2 nanoparticles on graphene and N-doped graphene sheets enhances their capacitive characteristics.