As an energy storage device, supercapacitors are practically used in many fields due to their high power density and long service life. Among the components of supercapacitors, electrode materials play a key role in the performance of the device, it is thus of great significance to prepare electrode materials with superior electrochemical performance. NiCo₂S₄ was prepared by a hydrothermal method using nickel acetate and cobalt acetate as raw materials, glutathione as a morphology control agent and a sulfur source. The effect of hydrothermal reaction time on the microstructure, morphology and electrochemical performance of NiCo₂S₄ was investigated. The results show that the NiCo₂S₄ material prepared under the action of glutathione has a yolk-shell structure. The specific capacitance is 1 552.7 F/g when the current density is 0.5 A/g, and the specific capacitance can be maintained at 61.3% at 10 A/g. After 2 000 cycles, the specific capacitance retention of the material can be maintained at 79.3%. A supercapacitor can be assembled with NiCo₂S₄ and activated carbon as positive and negative electrodes, respectively. This hybrid supercapacitor can provide 33.9 W·h/kg energy density when the power density is 800 W/kg. After 2 000 charge and discharge cycles, the specific capacitance retention rate is 89%.