Simulation of the electrochemical impedance response of SOFC anodes: from the microstructural reconstruction to the physically-based modelling

In this contribution, a combination of experimental and modelling techniques are integrated and applied to link the electrode microstructure to the performance and degradation of SOFC anodes. Symmetric anodes made of scandia-stabilized zirconia and nickel were fabricated with 30, 40 and 50% vol. of Ni. The impedance response of the samples was measured at 600-800°C in 50-100% wet H2. The microstructure of the electrodes was reconstructed from FIB-SEM tomography for the evaluation of the effective properties. This information was fed to a physically-based model that takes into account the main transport and reaction phenomena occurring within the electrode. Impedance spectra were simulated and fitted with a reduced number of material-specific electrochemical parameters, which showed a clear dependence on temperature and did not vary in different samples (Fig. 1). The same approach was used to decouple the microstructural contribution to performance of infiltrated electrodes [1]. The study reveals that the coupling among microstructural characteristics, impedance and degradation can be methodically addressed to gain a fundamental understanding and to provide design indications to improve the performance and the lifetime of electrodes.