Hierarchical Composite Electrodes of Nickel Oxide Nanoflake 3D Graphene for High-Performance Pseudocapacitors

NiO nanoflakes are created with a simple hydrothermal method on 3D (three-dimensional) graphene scaffolds grown on Ni foams by microwave plasma enhanced chemical vapor deposition (MPCVD). Such as-grown NiO-3D graphene hierarchical composites are then applied as monolithic electrodes for a pseudo-supercapacitor application without needing binders or metal-based current collectors. Electrochemical measurements impart that the hierarchical NiO-3D graphene composite delivers a high specific capacitance of approximate to 1829 F g(-1) at a current density of 3 A g(-1) (the theoretical capacitance of NiO is 2584 F g(-1)). Furthermore, a full-cell is realized with an energy density of 138 Wh kg(-1) at a power density of 5.25 kW kg(-1), which is much superior to commercial ones as well as reported devices in asymmetric capacitors of NiO. More attractively, this asymmetric supercapacitor exhibits capacitance retention of 85% after 5000 cycles relative to the initial value of the 1 st cycle.