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

Hierarchical MnO 2 @NiCo 2 O 4 core–shell nanostructures are well fabricated via a simple two-step hydrothermal process. The MnO 2 @NiCo 2 O 4 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 MnO 2 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 MnO 2 @NiCo 2 O 4 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 MnO 2 @NiCo 2 O 4 is the promising candidate of supercapacitors.