High performance porous nickel cobalt oxide nanowires for asymmetric supercapacitor

In this work, we present the formation of porous NiCo oxide nanowires from single crystal nickel cobalt bimetallic carbonate hydroxide nanowires (NiCo cNW) for supercapacitor applications. High aspect ratio NiCo cNWs are found to evolve from highly crystalline nickel cobalt layered double hydroxides through a dodecyl anion assisted crystallization-dissolution-recrystallization process. The porous nickel cobalt oxide (NixCo3-xO4) nanowire array is formed by the heat treatment of nickel cobalt bimetallic carbonate hydroxide nanowires on nickel foam (NF) for the assembly of supercapacitors. This binder free electrode shows a high specific capacitance of 1479 F g(-1) at 1 A g(-1) and 792 F g(-1) at 30 A g(-1), indicating an excellent rate capability. Asymmetric device is constructed from NixCo3-xO4 on NF and activated carbon (AC) with an operation potential from 0 to 1.6 V. It shows a high specific capacitance of 105 F g(-1) at a current density of 3.6 mA cm(-2), while it maintains 58.7 F g(-1) at 89.4 mA cm(-2). In addition, the asymmetric device shows good stability towards long time charge-discharge cycles. (C) 2013 Elsevier Ltd. All rights reserved.