Three-dimensional numerical simulation of oxygen isotope transport in lanthanum strontium manganese - Yttria-stabilized zirconia cathode of solid oxide fuel cell

Distribution of oxygen isotope 18O concentration which was labeled in lanthanum strontium manganese (LSM) – yttria-stabilized zirconia (YSZ) cathode of a solid oxide fuel cell (SOFC) is predicted through numerical simulations using a three-dimensional microstructure which was reconstructed by a focused ion beam-scanning electron microscopy (FIB-SEM). The electrochemical reaction under the SOFC operation is first numerically simulated, then the unsteady 18O transport is simulated by coupling self-diffusion by concentration gradient, migration by the electrochemical potential field, and electrochemical reaction at the triple phase boundaries. Predicted results were compared with the measured 18O concentration by a secondary ion mass spectrometry taken at the intermediate plane of the reconstructed 3D microstructure, which showed qualitative consistency between them. Thus, from the direct correlation of the electrochemical reaction and 18O concentration in an actual electrode microstructure, influence of electrochemical reaction was discussed. The present approach provides useful information for the interpretation of the oxygen labeling experiment results, which can cultivate better understanding of the electrochemical reaction mechanism in the SOFC electrodes.