Nickel hydroxide nanoflakes grown on carbonized melamine foam via chemical bath deposition for supercapacitor electrodes

Abstract

Ni(OH)2 nanoflakes were deposited on a carbonized melamine foam (CMF) substrate (Ni(OH)2 @CMF) via chemical bath deposition at room temperature. This was achieved by using three different Ni(OH)2 precursor solution concentrations. Ni(OH)2 @CMF-0.05 was obtained using a 0.05 M Ni(OH)2 solution and exhibited a high specific capacitance of 1066 F g-1 at a specific current of 1 A g-1; further, this material retained a specific capacitance of 698 F g-1 at a specific current of 5 A g-1. At a scan rate of 5 mV s-1, the specific capacitance of Ni(OH)2 @CMF-0.05 was 965 F g-1. This excellent electrochemical performance is ascribed to the large amount of functional groups in CMF, which allowed for its facile reaction with Ni(OH)2 during the synthesis of Ni(OH)2 @CMF as well as with the hydroxide ions in the electrolyte during charge/discharge cycles. The monolithic device, which was achieved owing to the three-dimensional structure of CMF, delivered a high energy density of 27.5 Wh kg-1 at a power density of 140 W kg-1 and a high power density of 7.5 kW kg-1 at an energy density of 6.6 Wh kg-1. The device retained 100% of its energy density after 8000 charge/discharge cycles. This work suggests a potential approach to utilize melamine foam as a substrate for the low-cost growth of metal hydroxide nanostructures that can be used as electrode supercapacitors.