Template-assisted synthesis of hierarchically hollow C/NiCo2S4 nanospheres electrode for high performance supercapacitors

Binary transition metal sulfides hold immense promise for use in energy storage devices thanks to their higher electronic conductivity and capacity compared to that of the mono-metal sulfides arising from the richer redox reactions. Herein, hierarchically hollow C/NiCo2S4 nanosphere composites have been synthesized through carbon coating and hydrothermal processes with SiO2 nanosphere and glucose as the hard template and carbon source, respectively. The interconnected NiCo2S4 nanosheets, void spaces in the interior of nanospheres and the conducive carbon layer enable the C/NiCo2S4 composite electrode to achieve an outstanding conductivity and good stability. Accordingly, the hollow C/NiCo2S4 nanosphere electrode exhibits an extraordinary specific capacitance of 1545 F g(-1), as well as an enhanced cycling stability (90.1% after 6000 cycles) at a high current density of 10 A g(-1). Satisfactory energy density (34.1 Wh kg(-1) at 160 W kg(-1)) and high power density (8000 W kg(-1) at 19.8 Wh kg(-1)) can be obtained by fabricating an asymmetric supercapacitor with activated carbon in the operation window of 0-1.6 V. These encouraging results further reveal the promising prospects of the as-prepared C/NiCo2S4 nanocomposite for high efficient electrochemical supercapacitor.