Simulation of electrochemical impedance spectra of solid oxide fuel cells using transient physical models

A general electrochemical impedance spectroscopy (EIS) modeling approach by directly solving a one-dimensional transient model based on physical conservation laws was applied for simulating EIS spectra of an anode-supported solid oxide fuel cell (SOFC) button cell consisting of Ni-yttria-stabilized zirconia vertical bar Ni-scandia-stabilized zirconia (ScSZ)vertical bar ScSZ vertical bar lanthanum strontium manganate (LSM)-ScSZ multiple layers. The transient SOFC model has been solved for imposed sinusoidal voltage perturbations at different frequencies. The results have then been transformed into EIS spectra. Six parameters had to be tuned (three for the cathode and three for the anode) and have been estimated using data from a symmetric cathode cell and from a button cell. The experimental and simulated EIS spectra were in good agreement for a range of temperatures (750-850 degrees C), of feed compositions (mixture of H-2/H2O/N-2). and of oxidants (air and oxygen). This approach can help in interpreting EIS spectra, as illustrated by identifying the contribution of transport limitation. (C) 2008 The Electrochemical Society.