Binary nickel-manganese hydroxide nanoflakes on ZnO nanowires prepared by pulse electrodeposition for high-performance supercapacitors

J-H Huang, Y-H Luo, W.P. Kang
National Tsing Hua University,
Taiwan

Keywords: supercapacitor, nanocomposite, binary nickel-manganese hydroxide

Summary:

Transition-metal oxides or hydroxides on nanostructured supports have been regarded as promising electrode materials for high-performance supercapacitors due to their high power density, good energy density, excellent cycle stability, and long lifetime. In this work, we demonstrated the fabrication of high-performance supercapacitor electrodes based on binary (Ni, Mn) hydroxide nanoflakes modified ZnO nanowire (NWs). The ZnO NWs were synthesized on fluorinedoped tin oxide (FTO) glass substrates by chemical bath deposition, followed by pulse electrodeposition of binary (Ni, Mn) hydroxide nanoflakes on the surface of ZnO NWs. The effects of the electrodeposition conditions as well as the precursor variables were systematically investigated. The ZnO NWs/Ni hydroxide nanoflakes nanocomposite electrode fabricated under the preferred pulse electrodeposition conditions exhibited a large specific capacitance of 1830 F/g, a high energy density of 51.5 Wh/kg, a high power density of 9 kW/kg, while only ~80 % specific capacitance retention after 1000 cycles. In contrast, the optimized ZnO NWs/(Ni, Mn) hydroxide nanoflakes nanocomposite electrode has achieved a slightly lower specific capacitance of 1642 F/g, an energy density of 42.2 Wh/kg, a power density of 9 kW/kg, and a higher capacitance retention of 94.7 % after 3000 cycles. The high supercapacitive performance combined with using of the low-cost and environmentally friendly materials will make the ZnO NWs/(Ni, Mn) hydroxide nanocomposite desirable for supercapacitor applications.