NiCo2S4 nanoparticles grown on reduced graphene oxides for high-performance asymmetric supercapacitors

Abstract The nanostructures of reduced graphene oxide (rGO)/NiCo2S4 are prepared using the simple hydrothermal method and the thermal treatment process, which could provide good conductivity and ideal specific surface area. The rGO/NiCo2S4 electrode shows a maximum specific capacitance of 1059 F g−1, excellent rate capability, and good cycle life. Furthermore, the three dimensional structures of rGO/MnO (3D rGO/MnO) are also synthesized by the hydrothermal method and the thermal treatment process, which have the high specific surface area and good conductivity. The rGO/MnO electrode exhibits a maximum specific capacitance of 469 F g−1. A rGO/MnO//rGO/NiCo2S4 asymmetric supercapacitors (ASC) is assembled using 2 M KOH solution as electrolyte, rGO/NiCo2S4 as positive electrode and rGO/MnO as negative electrode. The rGO/MnO//rGO/NiCo2S4 ASC shows an energy density of 38.8 Wh kg−1 at a power density of 0.4 kW kg−1 and a good cycle life, which provides a possibility toward actual application in energy-storage systems.