Rational construction of core–shell Ni3S2@Ni(OH)2 nanostructures as battery-like electrodes for supercapacitors

Abstract

Rationally constructing hybrid nanostructure electrodes is a promising approach for the development of high-performance supercapacitors. Here, we propose the fabrication of Ni₃S₂@Ni(OH)₂ nanostructures directly on Ni foam by employing hydrothermal and chemical bath processes. In this core–shell nanostructure, the design of conductive Ni₃S₂ nanorods directly on Ni foam without organic binders could ensure intimate contact and fast electron transport. Meanwhile, porous Ni(OH)₂ nanosheets coated on conductive Ni₃S₂ nanorods can effectively supply large surface areas with electrolyte and provide fast ion diffusion. Consequently, the as-fabricated Ni₃S₂@Ni(OH)₂ nanostructures showed good electrochemical performance, such as high capacitance up to 3.55 F cm⁻² and a good capacity retained after 10 000 cycles of about 85%. Furthermore, an asymmetric device, based on Ni₃S₂@Ni(OH)₂ and activated carbon, was also fabricated and achieved a maximum energy density of 60.5 W h kg⁻¹ at 1159 W kg⁻¹. These results suggest that the as-designed core–shell Ni₃S₂@Ni(OH)₂ nanostructures demonstrated in this research are promising electrode materials for energy storage.