Effects of SO2 in ambient air on the performance and durability of solid oxide fuel cell（SOFC） cathode were evaluated by galvanostatic measurement. Comparison between two cathode materials was made to consider the cathode degradation mechanisms. The degradation performance is associated with a slow decomposition of the La0.6Sr0.4Co0.2Fe0.8O3（LSCF） due to the segregation of strontium oxide. Negligible deterioration for （La0.7Sr0.3）MnO3 （LSM） cathode was caused by SO2 poisoning under a current density of 200 mA/cm2. Metal sulphate formation may explain a slight deterioration under increasing high the concentration of SO2. It was verified that the poisoning mechanism for the two cathode materials resulted from the gradual decomposition of the cathode materials.
Degradation induced by sodium chloride in air was investigated for （La0.8Sr0.2）0.98MnO3（LSM） and Lao.6Sr0.4Coo.2Fe0.sO3（LSCF） cathodes in solid oxide fuel cells（SOFC）. Cell performance was measured by volatilizing NaC1 to be supplied to the cathode at a constant current density of 200 mA/em2 for up to 100 h. At 800℃, an exposure of the cathode to 30 mg/L NaC1 caused negligible degradation of LSM at least for 100 h. Slight change in the composition of the cathode materials was observed which may imply the gradual degradation of cell performance for the long-term. In addition, cell performance degradation was compared between 700℃ and 900℃, being poi- soned by 30 mg/L NaCI. Degradation was negligible for LSM cathode, while LSCF cathode showed slightly poor to-lerance at 700℃ due to the decomposition of the cathode material. Further studies should be done to clarify the long-term influence of NaCI on cathode performance.
