IMPEDANCE SPECTROSCOPY - A METHOD FOR IN-SITU CHARACTERIZATION OF EXPERIMENTAL FUEL-CELLS

The combination of measurements of current-voltage curves and impedance spectroscopic data of fuel cell electrodes helps to understand the influence of electrode morphology on effective electrocatalytic behaviour of electrodes for alkaline and molten carbonate fuel cells. PTFE-bonded Pt-activated carbon electrodes and their ageing behaviour were investigated showing that the degree of pore-flooding changes with time and that slow poisoning deteriorates the catalyst over several 100 h. PTFE-bonded Raney-nickel anodes are shown to be only partially utilized. A drastic change of the morphology of Ni-sponge anodes and NiO-cathodes in molten carbonate fuel cells is shown to be mainly due to improved porosity and electrolyte wetting of both electrodes.