Interconnected NiCo2S4 - coated NiO nanosheet arrays as electrode materials for high-performance supercapacitors

3D network-like NiO nanostructures were electrochemically grown on nickel foam and then, NiCo2S4 nanoparticles were decorated on NiO for the fabrication of high performance supercapacitor electrode. To synthesize the interconnected NiO nanosheet arrays (INSA), at first, ZnO nanorods were electrochemically grown on nickel foam (NF) and then, NiO nanosheet arrays were electrodeposited on the NF/ZnO substrate under the optimized experimental conditions. Finally, after the removal of ZnO nanorods, nickel cobalt sulfide nanoparticles were deposited on NF/NiO by chemical bath deposition to fabricate NF/NiO/NiCo2S4 supercapacitor electrode. In electrode, the network-like interconnected NiO nanosheet arrays with enough interspace ensure the facile ion penetration into the structure, and NiCo2S4 nanoparticles forgive high conductivity. The surface morphology of the fabricated electrodes was studied by scanning electron microscopy (SEM) and their electrochemical behaviors were studied by various techniques including cyclic voltammetry (CV), galvanostatic charge-discharge (GCD) and electrochemical impedance spectroscopy (EIS). The fabricated electrode exhibits a high specific capacitance of 1984 mF cm(-2) at the current density of 1 mA cm(-2) and high power density of 2.53 W m (- 2) at the energy density of 0.68 Wh m (- 2). Finally, an asymmetric supercapacitor (ASC) device was assembled with NF/NiO/NiCo2S4 and the activated carbon-based electrode as positive and negative electrodes, respectively. The fabricated ASC provides a superior specific capacitance of 108.5 mF cm(-2) at the applied current density of 1.0 mA cm(-2), and delivered the energy density of 0.254 Wh m (- 2) at the power density of 7.82 W m (- 2) with the cycling stability of about 90% retention after 2000 cycles.