NiCo2S4/CuCo2S4 Composite Cathode Materials for High-Performance Supercapacitors

Abstract

Transition metal sulfides are considered as good electrode materials for supercapacitors due to their high specific capacity and good structural stability. However, its poor multiplicative performance and limited cycle life limit its wide application. To solve this problem, we synthesized NiCo₂S₄/CuCo₂S₄ bimetallic sulphide nanocomposites by combining NiCo₂S₄ with CuCo₂S₄ using a two-step hydrothermal method. Compared with NiCo₂S₄ and CuCo₂S₄ alone, the NiCo₂S₄/CuCo₂S₄ nanocomposites have higher specific capacity and better cycling stability as supercapacitor electrodes. The specific capacity value of the NiCo₂S₄/CuCo₂S₄ electrodes at 1 A g^-1 is 830.3 C g^-1 with a potential window of 0-0.5 V. The NiCo₂S₄/CuCo₂S₄ nanocomposites are used as the electrodes in supercapacitors. Ni₃S₄ and activated carbon as cathode and anode, respectively, the hybrid supercapacitor (HSC) assembled with NiCo2S4/CuCo2S4 electrodes has a capacitance value of 129.4 F g^-1 at 1 A g^-1 and an energy density of up to 52.9 Wh kg^-1 at 410 W kg^-1. Long-term electrochemical stability tests show that the retention of the electrochemical specific capacity is 54% after 16,000 cycles.