Asymmetric supercapacitors based on the in situ-grown mesoporous nickel oxide and activated carbon
In this work, an asymmetric supercapacitor was successfully assembled using mesoporous Ni foam/Cu/NiO composite and activated carbon (AC) as the positive and negative electrodes, respectively. Its electrochemical performance was investigated by cyclic voltammetry (CV), galvanostatic charging/discharging techniques, and electrochemical impedance spectroscopy (EIS) in 6 M KOH electrolyte solution. The as-fabricated asymmetric supercapacitor can be cycled stably and reversibly within the potential window between 0 and 1.8 V. A maximum specific capacitance of 76.2 F/g and a high energy density of 34.3 Wh/kg are achieved, which are comparable with other recently published works. Besides, the as-assembled asymmetric supercapacitor could deliver a maximum power density of 8.68 kW/kg because of its low internal resistance (3.2 Ω), which derives from the direct growth of mesoporous active materials on the metal surface without using any polymer additives. This high electrochemical performance shows great potential of the as-assembled asymmetric supercapacitor to serve as energy storage device for various applications.