Preparation of chestnut-like porous NiO nanospheres as electrodes for supercapacitors

Chestnut-like porous nanospheres (CPNs) of NiO were prepared using a simple hydrothermal method. Electrochemical tests indicate that the NiO electrodes exhibit a reversible capacitance of 982 F g(-1) at a current density of 1 A g(-1) in a 6 M KOH electrolyte. When assembling a supercapacitor with activated carbon (AC), the supercapacitor of AC/6 M KOH/NiO can deliver an energy density of 51.5 W h kg(-1) at 0.38 kW kg(-1) and even maintain 27.7 W h kg(-1) at 2.32 kW kg(-1). In addition, the nanospheres could be cycled 10 000 times in a 6 M KOH aqueous electrolyte. This excellent performance demonstrates that the chestnut-like porous NiO nanospheres will be of great promise for supercapacitors applied to large power devices such as electric vehicles.