Preparation of MnS/NiCo₂S₄ composite nanosheets self-supported electrode and the performance in water-system asymmetric supercapacitors

Abstract In this paper, the MnS@NiCo 2 S 4 composite self-supporting electrode was designed and prepared with a mixture of nickel, cobalt, and manganese sulfide as the research object. The capacitance of the electrode can reach 2, 372.7 F g −1 at the current density of 1 A g −1 , and the voltage window can also be widened to 0-0.6 V and maintains a multiplier performance of 62.1% at 10 A g −1 . Following 5, 000 cycles of charging and discharging, the electrode exhibits a capacity retention of 78.2% relative to its initial capacity, with the coulombic efficiency consistently hovering around 100%. This performance indicates that the electrode can carry out stable and reversible electrochemical processes. A supercapacitor assembled with 1 M KOH as the electrolyte, activated carbon as the anode, and MnS/NiCo 2 S 4 as the cathode, delivers an energy density of 46.9 W h kg −1 . In the life test of the charge and discharge cycle, the discharge capacity after 10, 000 cycles is 89.2% of the initial capacity, indicating that the device has good cycle stability. This study provides an idea for the potential application of metal sulfide-based electrodes with wide potential windows and high electrochemical properties in water asymmetric supercapacitors.