Facile synthesis of NiCo₂S₄ spheres with granular core used as supercapacitor electrode materials

NiCo₂S₄ spheres with granular core were designed and fabricated via an easy two-step hydrothermal reation: carbon sphere clusters were used as templates to obtain NiCo₂(OH)₆/C precursor, which reacted with sodium sulfide to synthesize granular NiCo₂S₄ and then, the precursor of NiCo₂S₄ was grown on the periphery of granular NiCo₂S₄ to form the unique structure. The NiCo₂S₄ spheres with granular core specific surface area reaches 26.61 m² g⁻¹, which is about twofold of granular NiCo₂S₄ (11.41 m² g⁻¹). Electrochemical performance of the electrodes has been investigated. The electrode of NiCo₂S₄ spheres with granular core displays high specific capacitance of 1156 F g⁻¹ at a current density of 1 A g⁻¹, which increases by 71% compared to that of granular NiCo₂S₄ (675 F g⁻¹). Upon 1000 charge/discharge cycles, the NiCo₂S₄ spheres with granular core electrode exhibits excellent cycling stability with 82% capacitance retention at 5 A g⁻¹. In view of the low cost and superior electrochemical performance, the NiCo₂S₄ spheres with granular core synthesized using carbon sphere clusters as templates could be a promising electrode material for supercapacitors.