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

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 asprepared electrode in terms of specific capacitance (C-s) of 1782 Fg(-1) at 1 Ag-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 C-s of 110 Fg(-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 12.66 Wh 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. (C) 2019 Elsevier B.V. All rights reserved.