Ultrathin nanosheet interconnected NixS6/Ni(OH)2 hybrid nanocages: successive self-sacrifice template fabrication and exceptional performance in supercapacitors

Abstract

Low-cost and highly electroactive nickel-based materials are important electrodes for the development of supercapacitors. The precise modulation of the morphology and microstructure has been a crucial measure to further enhance the electrochemical performance. Herein, a three-dimensional porous nanocage Ni_xS₆/Ni(OH)₂ hybrid formed by Ni_xS₆ nanoparticles anchored on Ni(OH)₂ nanoflakes was creatively synthesized via a simple and scalable approach, which was based on two-time ion exchange reactions of the Mg(OH)₂ precursor. Significantly, in asymmetric supercapacitors, the Ni_xS₆/Ni(OH)₂ hybrid exhibits a high specific capacitance of 2726 F g⁻¹ at a current density of 1 A g⁻¹ and an excellent energy density of 31.31 Wh kg⁻¹ at a power density of 62.56 W kg⁻¹, which are superior to those of the currently reported nickel sulfide electrode materials. Compared with the nanoflower-like Mg(OH)₂ and Ni(OH)₂ precursors, the Ni_xS₆/Ni(OH)₂ hybrid possesses hollow, abundant porous morphology and better electrical conductivity, which could provide a large contact surface area, shorter ion diffusion path and excellent charge transport, resulting in a dramatic improvement in electrochemical performance, making the Ni_xS₆/Ni(OH)₂ hybrid a superb cathode material for supercapacitors.