Facile synthesis of ZnCo2O4 nanowire cluster arrays on Ni foam for high-performance asymmetric supercapacitors

Abstract

ZnCo₂O₄ nanowire cluster arrays (NWCAs) were directly grown on Ni foam via a facile hydrothermal method. The resulting products were analyzed by using X-ray diffraction spectroscopy (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The ZnCo₂O₄ NWCAs on Ni foam were directly used as integrated electrodes for supercapacitors and exhibited a high specific capacitance of 4.05 F cm⁻² at 20 mA cm⁻² (1620 F g⁻¹ at 8 A g⁻¹) in 3 M KOH aqueous solution, and an excellent cycling ability at various current densities up to 100 mA cm⁻² (40 A g⁻¹); 90% of the initial capacitance remained after 6000 cycles. Moreover, the asymmetric supercapacitor had a high energy density of 41.00 W h kg⁻¹ at a power density of 384 W kg⁻¹ and 16.63 W h kg⁻¹ at a high power density of 2561 W kg⁻¹. Such excellent rate properties and superior cycling life suggest that ZnCo₂O₄ NWCAs can not only be applied in high energy density fields, but also used in high power density applications.