Fibrous MnO sub(2) electrode electrodeposited on carbon fiber for a fuel cell/battery system

A novel fibrous MnO sub(2) electrode for a fuel cell/battery system is fabricated on carbon fiber by the electrodeposition method. The characteristics of the fibrous MnO sub(2) electrode are examined by electrochemical impedance spectra, galvanostatic performance and cyclic voltammetry. The experimental results indicate that the fibrous MnO sub(2) electrodes are superior to pasted electrodes because of the following: (i) better contact between MnO sub(2) and the electrical conducting material; (ii) high charge-transfer rate because of a smaller diameter than conventional electrodeposited MnO sub(2) 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 MnO sub(2) 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 -MnO sub(2) after 2 h of electrodeposition at 0.01 A dm super(-2) current density.