Influence of water vapor on long-term performance and accelerated degradation of solid oxide fuel cell cathodes

The influence of water vapor in the air on the performance and durability of solid oxide fuel cell (SOFC) has been investigated for the-state-of-the-art cathodes, (La_0.8Sr_0.2)_0.98MnO₃ (LSM) and La_0.6Sr_0.4Co_0.2Fe_0.8O ₃ (LSCF). Durability experiments were carried out at 800 °C up to 1000 h with various water vapor containing-air fed to the cathode side. Both types of cathode materials were basically stable under typical water vapor concentrations in the ambient air. Degradations could be accelerated at much higher water vapor concentrations, which could be associated with the decomposition of the cathode materials. Temperature dependence of this degradation was analyzed between 700 °C and 900 °C under 10 vol% water vapor concentration, which showed that the effect of water vapor depends strongly on the temperature and led to a severe degradation at 700 °C within a short time period for both cathode materials.