Electrochemical Behavior of Phosphine Induced Anode Performance Degradation in a Planar SOFC: A Numerical Study

Abstract

A one-dimensional model was developed to predict the performance degradation of the SOFCs anode exposure of fuel contaminants found in typical coal syngas. This model is extended to a three-dimensional model to predict the phosphine induced performance degradation in relatively large planar cells operating on hydrogen. The model parameters are calibrated using button cell experiments conducted under accelerated tests conditions. These parameters are then used to perform simulations to predict fuel contaminant performance degradation of planar cells. The results from degradation simulations show that the contaminant coverage alter the initial current distribution, as well as the fuel and oxygen distribution inside the anode significantly. The electrochemical characteristic of the degraded cell is analyzed by performing impedance and polarization simulations at cell operating current. The polarization and impedance simulations are implemented by dividing the cell into three regions along the fuel flow direction. The results show that the degradation rates and the impedance behavior of planar cells are very different than those observed in button cells.

Performance Degradation Predictions Based on Microstructural Evolution Due to Grain Coarsening Effects in Solid Oxide Fuel Cell Electrodes

“…The multi-physics model could alternatively be coupled with a phase field-based coarsening model, 23,24 or the property models could be improved with additional experimental microstructural data, to optimize the overall cell design with respect to particle size distribution and phase volume fractions in addition to operating conditions. The same model framework could be applied to planar cells and cell stacks by considering additional physics of flow channels and heat transport, as was done by Sezer et al 45 to predict degradation rates at higher scales. Finally, these simulations analyze the impact of a single degradation process on long term SOFC performance.…”

CFD modelling of hydrogen starvation conditions in a planar Solid Oxide Fuel Cell

“…14-18) and charge balance (Eqs. [19][20][21][22][23][24]) solved in the model are presented below. Anode…”

“…Current redistribution caused by contaminant induced deactivation of some regions of the cell resulted in hydrogen starvation in the active regions, which in turn led to oscillations in the voltage and current. Flexibility of simulations and predictions of the I-V behaviour of a cell was presented in the paper 20 . A 3D CFD model was also applied to an anode-supported planar SOFC to investigate transport phenomena inside a fuel cell fed with hydrogen and to evaluate its overall performance 21 .…”

A Transient Three-Dimensional Mathematical Model for the Local Impedance and Polarization Performance of Planar SOFCs

“…This makes experimental measurements of planar cell impedance difficult as the noise and disturbances external to the cell is more likely to distort or even dominate the measurement. It is expected that impedance spectra in planar cells will differ from button cells due to the additional considerations of processes occurring in the flow channels such as variations in gas velocity and density or temperature gradients (2,3). Significant variations of these quantities along the channels would make it difficult to extrapolate from button cell experiments and simulations to predict the performance of planar cells.…”

“…In previous work the impedance was used to investigate non-uniform degradation of planar cells due to fuel contaminant poisoning (2,3). The goal of the present study is to gain a deeper understanding of the impedance spectra of planar SOFCs by systematically exploring the relationship between certain operating conditions and the impedance of planar cells both overall cell behavior and the response of the cell locally.…”