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

摘要

Design and fabrication of a hierarchical core/shell MgCo2O4@MnO2 nanowall arrays on Ni-foam by a facile two-step hydrothermal method. The electrochemical measurements prove these composites with MnO2 definitely offer better supercapacitive performance of the MgCo2O4 electrode material. The nanowall structure provides more active sites and charge transfer during the Faradic reaction. The MgCo2O4@MnO2 nanowall shows an excellent electrochemical performance (852.5 F g⁻¹ at 1 A g⁻¹). The asymmetric supercapacitor is composed of the MgCo2O4@MnO2 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 MgCo2O4@MnO2 nanowall shows excellent supercapacitive performance and has a great potential for more research and application in the asymmetric supercapacitor devices field.