Fibrous MnO2 electrode electrodeposited on carbon fiber for a fuel cell/battery system

A novel fibrous MnO2 electrode for a fuel cell/battery system is fabricated on carbon fiber by the electrodeposition method. The characteristics of the fibrous MnO2 electrode are examined by electrochemical impedance spectra, galvanostatic performance and cyclic voltammetry. The experimental results indicate that the fibrous MnO2 electrodes are superior to pasted electrodes because of the following: (i) better contact between MnO2 and the electrical conducting material; (ii) high charge-transfer rate because of a smaller diameter than conventional electrodeposited MnO2 particles (thus it is expected that the specific surface area would be higher); and (iii) a low overpotential. The morphology and the crystal structure of the fibrous MnO2 electrode are investigated by scanning electron microscopy and X-ray diffraction, respectively. The entire surface of the carbon fiber is found to be coated with gamma-MnO2 after 2 h of electrodeposition at 0.01 A dm(-2) current density. (C) 2011 Elsevier Ltd. All rights reserved.