▎ 摘　　要

The freestanding flexible graphene oxide electrode material with higher energy density was prepared by the self-assembly process. The graphene oxide film was reduced under the nitrogen atmosphere to form nitrogen doped reduced graphene oxide film (N-rGO). N-rGO films were directly employed as electrodes (both cathode and anode) and solid-state polyvinyl alcohol/phosphoric acid as the separator for the solid-state supercapacitor structure. The structure was characterized without any metallic current collector. The specific capacitance of the device was 397 F/g, higher than that of the conventional liquid electrolyte system used for supercapacitors. The higher capacitance of the N-rGO system significantly increases the energy and power density values. The assembled flexible freestanding solid-state supercapacitor can be potentially used for energy storage applications. (C) 2017 Elsevier B.V. All rights reserved.