Cathode reaction models and performance analysis of Sm_(0.5)Sr_(0.5)CoO_(3-δ)-BaCe_(0.8)Sm_(0.2)O_(3-δ)composite cathode for solid oxide fuel cells with proton conducting electrolyte

摘要

Cathode reaction models for solid oxide fuel cells with proton conducting electrolyte (H-SOFC) are proposed, and the reacting orders for each elementary step with respect to oxygen and water vapor partial pressure are calculated. The limiting steps of cathode reactions are investigated with Sm_(0.5)Sr_(0.5)CoO_(3-δ) (SSC)-BaCe_(0.8)Sm_(0.2)O_(3-δ) (BCS) composite cathodes. The results suggest that the migration of protons to TPBs and the surface diffusion of O_(ad)~- might be the limiting reactions for SSC-BCS composite cathodes in wet atmosphere, while the oxygen ions transferring into electrolyte, the reducing of O_(ad) to O_(ad)~-, and surface diffusion of O_(ad)~-might be the limiting reactions for SSC-BCS composite cathode in dry atmosphere.