A parametric study of the solid acid fuel cell cathode

Abstract A one dimensional macrohomogeneous model of a Solid Acid Fuel Cell (SAFC) is developed to identify the dominant parameters affecting cell performance. The model parameters are estimated through a computational sensitivity analysis in which one model parameter is varied to assess the range of values of that parameter yielding convergence and qualitatively reasonable fits. Using this analysis to provide initial values, the model is used to simultaneous fit a set of polarization curves with physical input data (derived from measurements) and model parameters. The Tafel slopes obtained in the model agree with those calculated assuming a single-electron transfer rate-limiting step and a transfer coefficient of 0.5 at 250 °C. The Open Circuit Voltage (OCV) drop agrees closely with the theoretical value at 250 °C. Based on the sensitivity analysis, permeability and roughness factor are key parameters for higher performance. The current density distribution and a breakdown of contributing overpotentials are calculated using the model parameters and presented. The results show the importance of limitations in available surface area and mass transport to the catalytic surface as the limiting processes in SAFC performance. This points to decreasing catalyst layer thickness and improved microstructural configuration as targets for SAFCs performance improvement.