Long term investigations of silver cathodes for alkaline fuel cells

Alkaline fuel cells (AFC) are an interesting alternative to polymer electrolyte fuel cells (PEFC). In AFC no expensive platinum metal is necessary; silver can be used for the oxygen reduction reaction (ORR) (cathode catalyst). For technical use of AFC the long term behavior of AFC components is important, especially that of the electrodes. The investigated cathodes for AFC consist of a mixture of silver catalyst and polytetrafluorethylene (PTFE) as organic binder rolled onto a metal web. The electrodes were electrochemically investigated through measuring V-i curves and electrochemical impedance spectroscopy (EIS). The electrochemical characterization and the long term tests were performed in half-cells at 70 degreesC using pure oxygen (1 bar) under galvanostatic conditions. The cathodes were electrochemically investigated in half-cells using reference electrodes (Hg/HgO) by periodically recording V-i curve and electrochemical impedance spectroscopy. In addition, the cathodes were physically characterized by scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). (C) 2003 Elsevier B.V. All rights reserved.