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

Abstract

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, NiCo₂S₄ compounds exhibit high theoretical specific capacity but poor cycling performance. To address this issue, we synthesize several NiCo₂S₄ 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.