Degradation of LSCF Cathode Induced by SO2 in Air

Monday, 27 July 2015
Hall 2 (Scottish Exhibition and Conference Centre)
H. Kishimoto, F. Wang, D. H. Cho, P. Lv, K. D. Bagarinao, K. Yamaji, T. Horita (Natl Inst of Advanced Industrial Science and Technology), and H. Yokokawa (The University of Tokyo)
SO2 is one of the most major impurities in air and it induces a performance degradation of SOFC cathodes.  Our group has investigated the enforced degradation behaviors of LSCF cathodes by SO2 containing air.  It has been clearly observed that SO2 induced degradation is affected by the SO2 concentration in air, the operating temperature, the Sr content in LSCF cathode, the flowrate of air, the humidity of air as well as cell operation.  We also find out that sulfur is a tendency to preferentially exist in the vicinity of the cathode/electrolyte interface.  In this presentation, we try to provide a comprehensive description of SO2 induced degradation of LSCF cathode from a thermodynamical perspective.  In progress of degradation, sulfur reacts with Sr component in LSCF and forms SrSO4.  As a result, both conductivity and oxygen reduction reaction activity of LSCF decrease.  There seems to be a relationship between increments of ohmic resistance and reaction resistance in each degradation step