High-performance asymmetric supercapacitor based on CdCO 3 /CdO/Co 3 O 4 composite supported on Ni foam.

A CdCO 3 /CdO/Co 3 O 4 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.