3D NiO nanowires@NiO nanosheets core-shell structures grown on nickel foam for high performance supercapacitor electrode

Abstract

A 3D core-shell NiO nanowires@NiO nanosheets at nickel foam (NF) was synthesized by using two different synthesis processes. One was hydrothermal synthesis for core material and other was microwave-assisted hydrothermal synthesis for shell material. In 3 M KOH, a good electrochemical performance was shown by the as-prepared electrode in terms of specific capacitance (Cs) of 1782 F g−1 at 1 A g−1 with 70.33% retention of its initial capacitance after 7000 galvanic charge-discharge (GCD) cycles. An asymmetric supercapacitor (ASC) was prepared using NiO nanowires@NiO nanosheets@NF as positive and activated carbon coated NF (AC@NF) as a negative electrode and showed Cs of 110 F g−1 with retention of 79.9% of its initial capacitance after 5000 GCD cycles. ASC exhibited the highest energy and power density of 39.18Wh kg−1 (at 906.59W kg−1) and 12.25 kW kg−1 (at 12.66Wh kg−1). The superior electrochemical characteristics owing to excellent synergistic effects associated with core-shell structure of NiO nanowires and nanosheets showed a great potential of core-shell NiO nanowires@NiO nanosheets@NF composite for energy storage applications.