NiO nanoflakes decorated needle-like MnCo2O4 hierarchical structure on nickle foam as an additive-free and high performance supercapacitor electrode

Although many researches have been made in the construction and fabrication of electrode materials for supercapacitors, it remains a difficult task to realize the application of the supercapacitor with high energy density. The binary MnCo2O4@NiO hierarchical electrode has been successfully fabricated on nickel foam (NF) without any binder or additives by simple hydrothermal methods and corresponding annealing processes. By virtue of constructing hierarchical core-shell structure with different morphologies and forming additive-free electrode, the composite electrode not only possesses abundant surface active sites for electrochemical reaction as well as large buffering space for volume deformation in the charging-discharging processes, but also shows the improved contacting area and electric conductivity between active substance and metal collector. The synthetic MnCo2O4@NiO/NF electrode presented higher specific capacitance (1186 F g(-1) under 1 A g(-1)) and long cycle lifespan (maintain 91% of the original capacitance over 5000 cycles) under a high current density of 10 A g(-1). Further, the asymmetric supercapacitor with MnCo2O4@NiO/NF electrode shows higher energy density of 42.2 Wh kg(-1) under a power density of 748.2 W kg(-1). These results demonstrate that the binary MnCo2O4@NiO hierarchical structure is the hopeful candidate material for high performance supercapacitor electrode.