Hierarchical FeCo2O4@CoSe core–shell nanosheet arrays on nickel foam for high-performance supercapacitor

Self-growing FeCo2O4@CoSe/NF layered core–shell composite materials on Ni foam (NF) were prepared by hydrothermal method and electrodeposition method. CoSe shell effectively increased the conductivity of FeCo2O4 core, and the synergistic effects of the two contents effectively improved the overall electrochemical performance. At a current density of 1A/g, FeCo2O4@CoSe/NF achieved a specific capacity of 724.2C/g and capacity retention rate of 94.1% after 5000 cycles. The assembled asymmetric capacitor (ASC) also achieved a high energy density of 57.19Wh/kg when the power density is 750 W/kg.