Three-dimensional modeling of performance degradation of planar SOFC with phosphine exposure

A three-dimensional computational model is developed to predict the performance degradation of planar SOFC anodes exposed to fuel contaminants commonly present in coal syngas. The model parameters are calibrated using data from button cell experiments. The calibrated model is then used to perform simulations to predict performance degradation of planar cells due to phosphine contamination. The results from degradation simulations show that the contaminant coverage alters the current and temperature distributions significantly. The electrochemical characteristics of the degraded cell are analyzed by performing impedance and polarization simulations. The impedance analysis is applied to the cell in three regions along the fuel flow direction to elucidate location specific degradation phenomena. The results show that the degradation rates and the impedance behavior of planar cells are very different and more complicated than those observed in button cells. In such cases, localized impedance analysis may be necessary to elucidate various degradation mechanisms.