Morphology and electrochemical properties of NiCo2O4 powders prepared by a facile hydrothermal method

Nano-sized NiCo2O4 powders were prepared by a facile hydrothermal method. The phase structure, particle morphology, specific surface area and pore size distribution of the powders were examined as a function of their calcination temperature. In view of utilization in supercapacitors, the electrochemical properties of the electrodes prepared from the powders were investigated by means of cyclic voltammetry, galvanostatic charge-discharge and electrochemical impedance spectroscopy techniques. In addition, the electrochemical properties of the electrodes were tentatively interpreted with respect to the kinetics parameters of electrons and ions involved in the electrode reaction. The NiCo2O4 powder calcined at 350 °C displayed nanorod morphology (30–50 nm in diameter and 200–400 nm in length) and optimal electrochemical properties among the investigated specimens. The electrode prepared from the powder displayed an outer voltammetric charge of 113 C/g and a charge transfer resistance of 0.39 Ω together with a specific capacitance of 343 C/g under current density of 1 A/g and a capacitance retention of 108% after 5000 charge/discharge cycles measured at 20 A/g.