Direct Redox Deposition of Manganese Oxide on Multiscaled Carbon Nanotube/Microfiber Carbon Electrode for Electrochemical Capacitor

Manganese oxide (MnO2) was synthesized by direct reduction of MnO4- ions on microfibrous carbon paper (CP) and a multiscaled substrate, which consists of microfibrous CP coated with carbon nanotubes. This process is much simpler than that used for the formation of composite electrode. Scanning electron microscopy and energy dispersive X-ray analysis revealed that the multiscaled carbon nanotube/microfibrous CP is efficient for the reduction of MnO4- ions that leads to the direct formation of MnO2. The capacitive behavior of the composite manganese oxide/CP (CP-MnO2) composite and the multiscaled carbon nanotube/microfibrous CP (CP-CNT-MnO2) nanocomposite electrode was characterized by cyclic voltammetry in neutral aqueous electrolyte (e.g., 0.65 M K2SO4) aqueous solution. The specific capacitance of the CP-CNT-MnO2 nanocomposite is as high as 322 F/g in comparison to that one of CP-MnO2, which is 125 F/g. The electrochemical impedance spectroscopy technique showed that the multiscaled CP-CNT-MnO2 nanocomposite electrode is characterized by a good electrical conductivity and an excellent electrical contact between the active material and the current collector. (C) 2009 The Electrochemical Society. [DOI: 10.1149/1.3090012] All rights reserved.