Construction of 8-MnO2/Mn2O3 flower sphere composite with two-dimensional hierarchical nanosheets as supercapacitor electrode with enhanced performance

Mn2O3 is and has received widespread attention in fields such as catalysis and energy storage. However, its poor conductivity limits its application as an electrode material for supercapacitors. Here, flower-like spheroidal 8-MnO2/Mn2O3 composites composed of two-dimensional (2D) hierarchical nanosheets were prepared by the template method and a simple hydrothermal process. The growth process and electrochemical properties of 8-MnO2/Mn2O3 composites were investigated by adjusting the concentration of KMnO4 in the hydrothermal process. Since the introduction of 8-MnO2 brings more pseudocapacitance to the composite, the synergistic effect between MnO2 and Mn2O3 reduces the interfacial resistance, and the unique nanosheet structure increases its specific surface area, which alleviates the volume expansion during the cycling, the 8-MnO2/Mn2O3 composite electrode exhibits high specific capacitance (182 F g-1 at 0.5 A g-1), fast rate performance (74.2% capacitance retention at 5 A g-1), and excellent cyclic stability (90.1% capacitance retention after 5000 cycles at 5 A g-1). Symmetric supercapacitors assembled with 8-MnO2/Mn2O3 electrodes also exhibit a high energy density of 9.1 Wh kg-1. 8-MnO2/Mn2O3 composites have greater application prospects in energy storage, and are expected to achieve further applications in lithium/sodium ion batteries, zinc ion batteries and other fields.