No abstract

The paper concentrates on the investigation of SOFC short stacks and stacks for mobile applications. A lightweight stack design was used, which is based on stamped metal sheet bipolar plates with anode supported cells (ASC). The stacks were electrochemically characterized mainly by long-term measurements, by current-voltage measurements and by impedance spectroscopy. The stacks were operated at different temperatures, varying fuel gas compositions, different flow rates and under dynamical electrical loading cycles. Their influence on the electrochemical performance of the short stacks is outlined. The fuel utilizations and the different power densities, i.e. area specific, gravimetric and volumetric ones, are presented. The nature of losses, e.g. ohmic and polarization resistances, were examined by combining the results of the current-voltage curves and the impedance spectra. Moreover, the degradation rates were determined from the long-term measurements. After operation, the stacks were examined by light microscopy and SEM in order to analyze possible degradation mechanisms.