Time and temperature dependent multiple hierarchical NiCo2O4 for high-performance supercapacitors

Abstract

A multiple hierarchical NiCo₂O₄ (denoted as P-100), which was constructed of nanosheets covered with nanowires, was obtained by a facial hydrothermal method in combination with annealing treatment at 300 °C. The hydrothermal temperature and reaction time play key roles in the formation of the unique hierarchical NiCo₂O₄ based on the morphology evolution. As a supercapacitor electrode material, the obtained P-100 displays a high specific capacitance of 1393 F g⁻¹ at 0.5 A g⁻¹. Furthermore, the assembled P-100//AC asymmetric supercapacitor demonstrates a high energy density (21.4 Wh kg⁻¹) at a power density of 350 W kg⁻¹ and remarkable cycling stability. The good electrochemical performances of the P-100 are mainly due to its three dimensional hierarchical porous nanostructure and high specific surface area as well as the synergetic effect of the nanosheets and nanowires in NiCo₂O₄. The experimental results demonstrated that the multiple hierarchical NiCo₂O₄ is a promising electrode material for high-performance supercapacitors.