Modeling of Solid Oxide Fuel Cell through Microkinetics

The development of reliable physicochemical models is important for improving the interpretation and performance of Solid Oxide Fuel Cells. This work develops a microkinetic framework for a Ni/YSZ anode operating with hydrogen and steam. The main contribution is the development of an analytical procedure for calculating the open-circuit voltage, the steady-state surface coverages, and the corresponding charge-transfer kinetic parameters. A complementary numerical procedure was also implemented in Cantera and MATLAB to determine the open-circuit steady state and verify the analytical results. A six-step reaction mechanism from the literature was reformulated according to Cantera conventions and used to calculate the transient electrochemical response. The framework was applied to impedance analysis, Distribution of Relaxation Times analysis, surface coverage analysis, sensitivity analysis, parameter optimization, polarization curves, and porous electrode conditions. The model showed good agreement with published surface coverages, impedance spectra, and polarization data. Parameter optimization produced only limited improvement, indicating that the remaining differences are mainly associated with transport phenomena not included in the model. Overall, the results consistently showed that reactions involving OH species have the strongest influence on the electrochemical response, with the largest effects observed in the impedance and polarization results.