Impedance simulation of a solid oxide fuel cell anode in time domain

The purpose of the current study is to simulate the behavior of a solid oxide fuel cell (SOFC) anode under sinusoidal excitation. The obtained harmonic response is used as a base for electrochemical impedance spectra simulation. The electrochemical impedance spectroscopy (EIS) is a powerful non-destructive tool for SOFC researches. In order to evaluate the EIS experimental results, efforts are devoted to develop EIS numerical simulation tools. In this study, a planar SOFC is modeled, and the steady state behavior and frequency response, as well as the electrochemical spectra of the anode, are obtained. The developed model couples the electrochemical kinetics with mass transport. The Butler-Volmer equation is used for the anode electrochemistry, and the species equations are used for gas transport in the anode channel. In order to solve the system of the nonlinear equations, an in-house code based on finite difference method is developed and utilized. A parametric study is also carried out, and the results are discussed. The simulation results are in good agreement with published data. Results show a capacitive semicircle in the Nyquist plot, which is identical to the gas diffusion impedance as reported in literatures.