Self-supported two-dimensional NiCo2S4 micro-spheres for ultra-high supercapacitor application via two-step methods: Electro-deposition and chemical vapor deposition

A self-supported NiCo2O4 on Ni foam was prepared by electro-deposition method. Then the NiCo2S4 micro- spheres are derived by sulfurizing the NiCo2O4 using CVD at 300°C and explored its energy storage performance towards supercapacitor. Importantly this type of micro-sphere like geometry provides better exposure of redox active sites and more accessible surface area showing enhanced charge accumulation rate. These NiCo2S4 micro-spheres shows excellent charge storage performance in terms of very high specific capacitance value of 1111 F g−1 at current density 20 A g−1 and high energy density of 39 W h kg−1 at power density 23 kW kg−1 with a prolonged cycling stability over 5000 repeated cycles. Owing to excellent electrochemical performances, we presume that the as synthesized NiCo2S4 micro-spheres would be a permissible and efficient active electrode material for future energy storage systems.