Sulfur Poisoning of SOFC Cathodes

In order to examine degradation of solid oxide fuel cell (SOFC) cathodes due to a trace of in air, sulfur poisoning of SOFC cathodes was investigated in an accelerated mode using -concentrated air at . Two different cathode materials, (SSC) and (LSM), were fired on button-type electrolytes. -concentrated air ( –air mixture) was selected as the source of sulfur in order to accelerate degradations due to sulfur poisoning. By exposure to , the performance of SSC cathode rapidly declined, because both ohmic and polarization resistances increased. The performance of the LSM cathode slightly decreased after exposure to , and the performance recovered by interrupting the feed of . Secondary phases such as strontium sulfate were formed on SSC cathode after exposing and were not clearly detected on LSM cathode. The LSM cathode was more stable in concentrated air than the SSC cathode. This can be explained by the difference in the activity of strontium oxide in LSM and SSC.