Cobalt sulfide nanosheets coated on NiCo2S4 nanotube arrays as electrode materials for high-performance supercapacitors

Abstract

Hierarchical hybrid electrodes were successfully fabricated by electrodeposition of ultrathin cobalt sulfide (CoS_x) nanosheets on NiCo₂S₄ nanotube arrays grown on Ni foam for high-performance supercapacitors. The hierarchical NiCo₂S₄@CoS_x core/shell nanotube arrays exhibit a high areal capacitance (4.74 F cm⁻² at a current density of 5 mA cm⁻²), a good rate capability (2.26 F cm⁻² at 50 mA cm⁻²) and cycle stability (76.1% capacitance retention after 1500 cycles at a high current density of 50 mA cm⁻²), which are much better than those of NiCo₂S₄ nanotubes. Such superior electrochemical performance could be attributed to the smart configuration of the two electroactive materials, which can provide more pathways for electron transport and improve the utilization rate of the electrode materials. This effective strategy shows the feasibility of designing and fabricating metal sulfides with core/shell hybrid structures as electrode materials for high-performance supercapacitors.