Construction and application of NiCo₂O₄@MnS composite with hierarchical structure for hybrid supercapacitor

The development of an electrochemical energy storage system with exceptional performance is an important way to address the energy crisis and environmental pollution of the modem world. In this study, an NiCo₂O₄@MnS composite with a unique hierarchical structure has been successfully synthesized on an NF substrate using the hydrothermal-electrodeposition method. The results indicate that NiCo₂O₄@MnS possesses superior specific capacitance and excellent cycling stability. At a current density of 2 A g^-1, its specific capacitance can reach 2100 F g^-1, while the capacitance retention is still 76% after 10 000 cycles at 10 A g^-1. Moreover, when the current density is 1 A g^-1, the assembled NiCo₂O₄@MnS//AC device can deliver a specific capacitance of 203 F g^-1, and the energy density is up to 55 W h kg^-1 at a power density of 697 W kg^-1. These outstanding electrochemical properties of NiCo₂O₄@MnS can be ascribed to the increase in ion diffusion, specific surface area and electronic conductivity due to its unique hierarchical structure and introduction of MnS.