Atomic-resolution analysis of degradation phenomena in SOFCS: A case study of SO2 poisoning in LSM cathodes

Solid oxide fuel cell (SOFC) degradation studies are often performed by scanning transmission electron microscopy (STEM), scanning electron microscopy (SEM), and X-ray diffraction (XRD). However, it is difficult to use these techniques to observe processes occurring at the smallest scales. Here, we study sulfur poisoning of La0.8Sr0.2MnO3−δ (LSM) cathodes as a model case for atomic resolution scanning transmission electron microscopy (STEM) analysis with energy dispersive X-ray diffraction (EDX). Significant SrSO4 nanoparticle formation is observed after SO2 exposure, especially at grain boundaries in the LSM. In addition, La2O3 formation inside the grain was also confirmed. The formation of SrSO4 is identified with irreversible SOFC degradation, in addition to simple SO2 adsorption, which is reversible.