Integrated Effects of NiCo2O4 and Reduced Graphene Oxide in High-Performance Supercapacitor Systems

Supercapacitors have attracted significant interest as increased energy storage devices due to their high power density, rapid charge/discharge performance, and long cyclability. In this study, NiO, Co3O4, NCO, and NCO/rGO composite electrodes were prepared and evaluated for high-performance supercapacitor applications. The uniform distribution of elements and the effective incorporation of rGO into the composite were confirmed by structural and morphological characterizations. Among the evaluated materials, the NCO/rGO electrode exhibited high electrochemical performance, delivering a specific capacitance of 998 F g−1 in a three-electrode configuration, attributed to the enhanced redox activity of NiCo2O4 coupled with the enhanced electrical conductivity of rGO. Additionally, an asymmetric supercapacitor device with activated carbon as the negative electrode and NCO/rGO as the positive electrode showed a power density of 750 W kg−1, an energy density of 29.2 Wh kg−1, and a specific capacitance of 93.7 F g−1. After 5000 charge/discharge cycles, the device maintained 85% of its initial capacitance and a coulombic efficiency of 99%, demonstrating exceptional cyclability. These results highlight the strong potential of the NiCo2O4/rGO composite as an advanced electrode material for next-generation energy storage systems.