Annealing temperature dependent ZnCo2O4 nanosheet arrays supported on Ni foam for high-performance asymmetric supercapacitor

Porous network ZnCo2O4 nanosheets are successfully achieved by a simple hydrothermal process and adjusting the annealing temperature. The electrochemical performance of ZnCo2O4 nanosheets is significantly influenced by different annealing temperatures. It has been discovered that electrode of ZnCo2O4 that has be annealed at 200 °C shows an ultrahigh areal capacitance of 3.19 F cm−2 at a current density of 2 mA cm−2. An asymmetric supercapacitor device was assembled by ZnCo2O4 annealed at 200 °C as positive electrode and activated carbon as negative electrode, which exhibits the energy densities of 50.7 and 37.7 Wh kg−1 at power densities of 187.6 and 2950.4 W kg−1, respectively.