Self-standing manganese oxide decorated carbon nanotube electrodes for high-rate supercapacitors

Abstract

In this paper, we report the performance of a high-capacity, fast-charging, and reliable supercapacitor consisting of manganese dioxide (MnO2) on carbon nanotube (CNT) electrodes fabricated using a simple and efficient electrodeposition method. The MnO2@CNT composite electrodes formed on a flexible carbon fabric demonstrated excellent electrochemical energy storage capabilities as confirmed by cyclic voltammetry (CV) and galvanostatic charge-discharge (GCD) experiments. The MnO2 loading significantly affected the electrode's capacity, with the highest specific capacitance of 219 F g-1 achieved at low mass loading (3.37 mg cm-2 ) and the highest areal capacitance of 1.5 F cm-2 for high mass loading (15.6 mg cm-2 ). The electrode also showed outstanding stability, retaining 87% of its initial capacity after 2000 cycles. Electrochemical impedance spectroscopy (EIS) measurement and corresponding analysis of the data indicated fast charge transfer kinetics and facile ion diffusion into the MnO2 electrode, which is attributed to the nanoflower-like structure of MnO2 formed on porous carbon nanotubes, leading to excellent rate performance.