A facile preparation of NiO/Ni composites as high-performance pseudocapacitor materials

Abstract

We report a facile way to prepare NiO/Ni composites with a positive on their specific capacitances as supercapacitor electrodes. Various NiO/Ni composites were obtained by controlling the reduction time of NiO by H₂. The morphology of the products was characterized by transmission electron microscopy (TEM) and scanning electron microscopy (SEM). The electrochemical performance of electrodes was investigated by cyclic voltammetry (CV) and the galvanostatic charge/discharge test. The results of electrochemical tests show that the as-prepared NiO and NiO/Ni all reveal stable cycling performance and remarkable rate performance. The resulting NiO/Ni40, obtained by calcining NiO in H₂ for 40 min, could achieve a high specific capacitance of 760 F g⁻¹ at 20 A g⁻¹, significantly higher than the 480 F g⁻¹ found for NiO. Additionally, the specific capacitance of NiO/Ni40 remained as high as 816 F g⁻¹ after a 1000-cycle test at 4 A g⁻¹, revealing superb electrochemical characteristics. This study provides a viewpoint that the introduction of an appropriate amount of Ni particles could enhance the specific capacitance of NiO as a supercapacitor electrode.