Abstract

A CdCO3/CdO/Co3O4 composite has been prepared on nickel foam through a combined hydrothermal-annealing method. An asymmetric hybrid supercapacitor (SC) device was assembled with this composite as the positive electrode and activated carbon was the negative electrode. The SC exhibited a high specific capacitance of 84 F g(-1) @ 1 mA cm(-2), a maximum energy density of 26.3 W h kg(-1), and a power density of 2290 W kg(-1), along with a wide potential window of 1.5 V and long cycle life (92% after 6000 cycles). SCs assembled in series powered various light-emitting diodes and moved an electrical mini-motor.