Fabrication of carbon nanotube/NiOx(OH)y nanocomposite by pulsed electrodeposition for supercapacitor applications

Abstract

Nanocomposite films based on carbon nanotubes (CNTs)/nickel (Ni)-species were fabricated by electrophoretic deposition (EPD) of CNT, followed by pulsed electrodeposition of Ni and annealing in air. NiO/Ni(OH)2 particles with 7 ± 4 nm diameters were uniformly dispersed on the CNT networks. Cyclic voltammetry revealed that the CNT/NiOx(OH)y nanocomposite films had high specific capacitances of 1451, 1158, 998, 896 and 851 F g^{−1} per mass of active Ni species at 1, 10, 30, 50 and 100 mV s^{−1}, respectively, in the potential window of 0.4 V. An annealing time of 1 h (at 523 K) enhanced the pseudocapacity of deposited Ni species by the dehydration of Ni(OH)2 to form NiO. Longer annealing time reduced the capacitance because of sintering and subsequent decrease in surface area of Ni deposits. The capacitance of the fabricated CNT/NiOx(OH)y nanocomposite was maintained after 20, 000 cycles of potential sweeping.