Flexible metal-free supercapacitors based on multilayer graphene electrodes

We report the development of flexible self-supported metal-free electrodes based on non-oxidized graphene multilayer (MLG) paper, utilized to assemble bendable electrochemical supercapacitors. Using a simplified production method various electrodes exhibiting high conductivity were prepared and its structural, morphological, chemical and electrical properties characterized. Measurements in supercapacitors assembled from MLG electrodes and PANI-coated MLG electrodes show excellent electrochemical characteristics, with specific capacitances of 58 mF cm(-2) and 451 F g(-1) with 84% and 103% of capacitance retention after 1000 cycles, respectively. The energy and power density obtained for the PANI/MLG flexible supercapacitor reached 17.0 Wh g(-1) and 3.61 kW kg(-1), respectively. Moreover, in bending tests, the supercapacitors displayed an excellent mechanical and electrochemical stability. As an important result of this study, MLG electrodes appear as an interesting material for flexible high performance energy storage devices. (C) 2018 Elsevier Ltd. All rights reserved.