Urchin-Like NiCo₂O₄@Ni₃S₂ Core/Shell Nanostructure as Supercapacitor Electrode

Urchin-like NiCo₂O₄ nanoneedles were grown on a nickel foam via hydrothermal synthesis, and then the surface of the structure was modified to a candle-like nano-array via electrodepositing of Ni₃S₂. The resulting structure was analyzed as a supercapacitor electrode by x-ray diffraction, high-resolution scanning electron microscopy, and electrochemical measurements. Based on the electrochemical measurements, the NiCo₂O₄@Ni₃S₂ core–shell structure electrode exhibited a remarkable specific capacity of 1800 F g⁻¹, and a rate capability of 1764 F g⁻¹ at 2 mVs⁻¹. This electrode also maintained 98% capacity after 2000 cycles at this current density. These results are promising compared to the electrochemical performance of the NiCo₂O₄ electrode (specific capacity of 1460 F g⁻¹ and 86% capacity retention after 2000 cycles at a scan rate of 2 mVs⁻¹). It is therefore concluded that the surface modification of the NiCo₂O₄ electrode facilitates electron transfer and cause an advancement in the capacitive performance of the NiCo₂O₄@Ni₃S₂ electrode.