Fabrication of hierarchical core/shell MgCo2O4@MnO2 nanowall arrays on Ni-foam as high–rate electrodes for asymmetric supercapacitors

Design and fabrication of a hierarchical core/shell MgCo 2 O 4 @MnO 2 nanowall arrays on Ni-foam by a facile two-step hydrothermal method. The electrochemical measurements prove these composites with MnO 2 definitely offer better supercapacitive performance of the MgCo 2 O 4 electrode material. The nanowall structure provides more active sites and charge transfer during the Faradic reaction. The MgCo 2 O 4 @MnO 2 nanowall shows an excellent electrochemical performance (852.5 F g −1 at 1 A g −1 ). The asymmetric supercapacitor is composed of the MgCo 2 O 4 @MnO 2 nanowall and the activated carbon (AC). The energy densities of the asymmetric supercapacitor device can keep up 67.2 Wh·kg −1 at 5760.0 W·kg −1 . The MgCo 2 O 4 @MnO 2 nanowall shows excellent supercapacitive performance and has a great potential for more research and application in the asymmetric supercapacitor devices field.