All-Solid-State Symmetric Supercapacitor Based on Co3O4 Nanoparticles on Vertically Aligned Graphene.

We have synthesized the hybrid supercapacitor electrode of Co3O4 nanoparticles on vertically aligned graphene nanosheets (VAGNs) supported by carbon fabric. The VAGN served as an excellent backbone together with the carbon fabric, enhancing composites to a high specific capacitance of 3480 F/g, approaching the theoretical value (3560 F/g). A highly flexible all-solid-state symmetric supercapacitor device was fabricated by two pieces of our Co3O4/VAGN/carbon fabric hybrid electrode. The device is suitable for different bending angles and delivers a high capacitance (580 F/g), good cycling ability (86.2% capacitance retention after 20 000 cycles), high energy density (80 Wh/kg), and high power density (20 kW/kg at 27 Wh/kg). These excellent electrochemical performances, as a result of the particular structure of VAGN and the flexibility of the carbon fabric, suggest that these composites have an enormous potential in energy application.