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The low power range can be an interesting application market for the PEM fuel cell in the near future. With a possible function as battery in portable devices the banded structure PEM fuel cell will be an advantageous alternative to the conventional stack. The new system provides high output voltages, a flat cell geometry and can be optimized with respect to smaller cell volumes. The article describes the principle function of such a system and the necessary parameter for optimizing the cell geometry. A comparison with a conventional stack design is given and experimental results with an eight cell banded structure stack are presented.

The RSPFC is a battery-like hydrogen/oxygen system which offers the possibility of splitting water by electrolysis, storing the gases hydrogen and oxygen and regenerating electricity by the fuel cell process. The most outstanding feature is the use of only one energy conversion device for both processes, electrolysis and fuel cell operation. Membrane technology is the most suitable system for realization of this concept. Basic investigations concerning the best catalysts for the electrode reactions at electrode/membrane units have been carried out. The preparation of these units and the electrochemical characterization by half cell measurements and impedance measurements are reported as well as first experiences in reversibly operating small single cells.

Using Simultaneous Electrochemical Electron Spin Resonance spectroscopy (SEESR), formylra- dicals have been identified as intermediates in the electrooxidation of methanol and formaldehyde at a platinum electrode in sulphuric acid solution. The lifetime of the radicals is too short as to allow direct detection, this holds true even after an increase in the sensitivity of the method by additional potential modulation. Thus for a successful detection spin traps, formed electrochemically in situ , have been used.