Synthesis of urchin-like NiCo 2 S 4 electrode materials based on a two-step hydrothermal method for high-capacitance supercapacitors.

Transition metal sulfides have been considered as promising electrode materials for future super-capacitors due to their spinel structures and environmentally friendly properties. Among these materials, NiCo 2 S 4 compounds exhibit high theoretical specific capacity but poor cycling performance. To address this issue, we synthesize several NiCo 2 S 4 urchin balls. The NCS-1.5 nanospheres demonstrate a specific capacitance of 1352.2 F g -1 at a current density of 1 A g -1 , and maintain high specific capacity after 10 000 charge-discharge cycles. An asymmetric capacitor assembled with the NCS-1.5 sample as the cathode and activated carbon as the anode achieve an energy density of 45.5 W h kg -1 at 2025 W kg -1 . The urchin-like nanospheres also facilitate the combination with other materials, providing potential insights for the synthesis of supercapacitor electrode materials.