Facile hydrothermal synthesis of actiniaria-shaped α-MnO2/activated carbon and its electrochemical performances of supercapacitor

In this work, the α-MnO2 and α-MnO2/activated carbon composite were prepared by a facile hydrothermal method. Effects of reaction time (1–12 h) and MnO2 loading (10–70%) on structure and electrochemical performances for materials were studied. Samples were analyzed by X-ray diffraction, scanning electron microscope, galvanostatic charge/discharge, cyclic voltammetry and Mott-Schottky testing. A growth model was used to describe the development mechanism of α-MnO2, and MnO2 samples prepared at 6–12 h displayed the actiniaria-shaped structure. The MnO2 electrode at 6 h exhibited the largest specific capacity of 629.2 C/g in K2SO4 electrolyte. After incorporation of carbon, the composite expressed low resistance and large carrier concentration than single MnO2. Due to good conductivity of carbon, the capacity of MnO2/carbon was up to 977.4 C/g (55.3% higher than MnO2). After 3000 cycles at 0.2 A/g, the MnO2/carbon exhibited higher capacity retention of 81.3% than 56.2% for MnO2. It indicated that the α-MnO2/activated carbon showed potential application as electrode material for supercapacitor.