Comparative supercapacitance performance of CuO nanostructures for energy storage device applications

Abstract

In the present study, three different morphologies of copper oxide (CuO) nanostructures; bud-, flower- and plate-shaped CuO structures were synthesized by a simple chemical method. Binder-included pseudocapacitor electrodes were prepared using bud- and flower-shaped CuO structures whereas, directly grown CuO-nanoplates on Ni foam were used as a binder-free electrode in a three-electrode setup for electrochemical studies. Remarkably, the binder-free CuO nanoplates electrode exhibited excellent specific capacitance of 536 F g⁻¹ at a current density of 2 A g⁻¹, whereas the binder-included electrodes of bud- and flower-shaped CuO exhibited 230 F g⁻¹ and 296 F g⁻¹, respectively, at a current density of 0.7 A g⁻¹ in a 6 M KOH electrolyte. The cycling retention test and charge/discharge stability for the binder-free CuO nanoplates electrode showed 94% capacity retention after 2000 cycles and capacitance loss of only 11.3% over ∼1000 cycles at a current density of 4 A g⁻¹ from charge/discharge measurements. Also, the binder-free CuO electrode showed higher energy and power densities of 29.4 W h kg⁻¹ and 12.7 W kg⁻¹, respectively, at 1.96 A g⁻¹ in an asymmetrical device, when compared to the binder-included electrode of flower-shaped CuO.