Facile synthesis of MnO2@NiCo2O4 core-shell nanowires as good performance asymmetric supercapacitor

Hierarchical MnO2@NiCo2O4 core-shell nanostructures are well fabricated via a simple two-step hydrothermal process. The MnO2@NiCo2O4 core-shell nanostructures materials electrode presents a high capacitance of 684 F g(-1) at 2 A g(-1) current density, 40 times higher than that of the single MnO2 nanowires electrode. And 87.4% retain is approached even at a high current density of 15 A g(-1), showing satisfactory rate capability. Furthermore, the theoretical analysis reveals the surface capacitance contribution is predominant in the capacitive contribution. The asymmetric supercapacitor assembled with MnO2@NiCo2O4 exhibited a maximum energy density of 35.6 Wh kg(-1) and a maximum power density of 745.1 W kg(-1). After 7000 charge-discharge cycling at a current density of 4 A g(-1), it still can maintain 90% of the initial capacitance. These results suggest that MnO2@NiCo2O4 is the promising candidate of supercapacitors.