Effect of calcination methods on electrochemical performance of NiO used as electrode materials for supercapacitor

Ni(OH)2 precursors were prepared via the precipitation transformation method, which was originated from Na2C2O4, NiSO4·6H2O and urea. NiO samples were successfully obtained by calcining Ni(OH)2 precursor with different calcination methods. Some were calcination in a tube furnace under the nitrogen flow and others were calcination in a muffle furnace. The products were well-characterized by thermogravimetric analysis (TGA), X-ray diffraction (XRD) and scanning electron microscopy (SEM). The influence of calcination methods on electrochemical performance of NiO samples were investigated. Moreover, the possible reason was proposed. The charge storage mechanism of NiO positive electrode in aqueous electrolyte was discussed. The electrochemical test showed that the as-prepared NiO prepared in a tube furnace can exhibit a good pseudocapacitance behaviour due to the higher utilization of active material.