Hierarchical porous NiCo2O4 nanograss arrays grown on Ni foam as electrode material for high-performance supercapacitors

Abstract

A novel hierarchical porous NiCo₂O₄ nanograss array directly grown on Ni foam is successfully synthesized through a facile hydrothermal method combined with a thermal treatment. When used as the electrode material for supercapacitors, an areal capacitance of 2.1 F cm⁻² was obtained under a current density of 2 mA cm⁻². After 4000 charge–discharge cycles, a high areal capacitance retention of 88% could be achieved. The outstanding electrochemical performance was attributed to the novel structure of the hierarchical porous NiCo₂O₄ nanograss arrays and the Ni foam used as the current collector. The novel hierarchical porous NiCo₂O₄ nanograss arrays are a promising electrode material for supercapacitors.