Carbon Nanotube/Manganese Oxide Ultrathin Film Electrodes for Electrochemical Capacitors

Abstract

Multiwall carbon nanotube (MWNT)/manganese oxide (MnO₂) nanocomposite ultrathin film electrodes have been created via redox deposition of MnO₂ on layer-by-layer (LbL)-assembled MWNT films. We demonstrate that these LbL-assembled MWNT (LbL-MWNT)/MnO₂ thin films consist of a uniform coating of nanosized MnO₂ on the MWNT network structure using SEM and TEM, which is a promising structure for electrochemical capacitor applications. LbL-MWNT/MnO₂ electrodes yield a significantly higher volumetric capacitance of 246 F/cm³ with good capacity retention up to 1000 mV/s due to rapid transport of electrons and ions within the electrodes. The electrodes are generated with two simple aqueous deposition processes: the layer-by-layer assembly of MWNTs followed by redox deposition of MnO₂ at ambient conditions, thus providing a straightforward approach to the fabrication of high-power and -energy electrochemical capacitors with precise control of electrode thickness at nanometer scales.