Hetero-nanostructures constructed by 2D porous metal oxide/hydroxide nanosheets supported on 1D hollow Co9S8 nanowires for hybrid supercapacitors with high areal capacity

Abstract

The rational design of positive electrodes for hybrid supercapacitors is profound for applications in energy storage and conversion. Herein, we designed porous-hollow Co₉S₈/NiCo-Mo one-dimensional (1D) hetero-nanostructures on carbon cloth as battery-type electrodes. In particular, Ni–Co double hydroxide and Mo oxide grow on the surface of hollow Co₉S₈ nanowires, providing rich active sites. Meanwhile, the hollow structure of the Co₉S₈ nanowires is beneficial for electrolyte penetration and slows down the volume change caused by the continuous charge and discharge process. Moreover, the Co₉S₈/NiCo-Mo oxide/hydroxide electrode exhibits a remarkable areal capacity of 3.07 mA h cm⁻² (1 mA cm⁻²), and a hybrid supercapacitor based on Co₉S₈/NiCo-Mo nanostructures and activated carbon (AC) can output a high specific energy of 37.6 W h kg⁻¹ at a specific power of 228.7 W kg⁻¹ with decent cycling stability (capacity retention of 87.7% after 10 000 cycles). Two connected HSCs can light up a red-light emitting diode (LED) and make the motor turn for more than 5 min. The results indicate that the unique integrated Co₉S₈/NiCo-Mo nanostructure shows great potential as a novel battery-type electrode for supercapacitors.