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.