Shape-controlled synthesis of nickel–cobalt–sulfide with enhanced electrochemical activity

Abstract

Morphology control of electrode material is critical for high performance supercapacitors. The synthesis of shape-controlled materials is helpful to design advanced electrode materials for supercapacitors. Herein, we prepared two types of NiCo₂S₄ with nano-bud and nano-mesh morphologies under hydrothermal conditions by facile controlling the reaction time. These materials display morphology-dependent electrochemical activity. Electrochemical measurements showed that the nano-mesh-like NiCo₂S₄ demonstrate the superior pseudocapacitive performance with a high specific capacitance (3.00 F cm⁻² or 1250 F g⁻¹ at 2 mA cm⁻²) and a favorable rate capability (77.8% from 2 to 25 mA cm⁻²). Moreover, the specific capacitance remains 80% of its initial value after 5000 cycles even at high current density of 20 mA cm⁻². The mesh-like NiCo₂S₄ also displays a low overpotentials of 299 mV at the current density of 30 mA cm⁻², showing better performance in electrochemical oxygen evolution reaction.