Degradation of LSCF Cathode Induced by SO2 in Air

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