Correlating the Oxygen Redox Chemistry and Oxygen Nonstoichiometry at La{sub}(1-x)Sr{sub}xMnO{sub}(3±δ)SOFC Cathodes

摘要

This work uses the Wagner Factor as a qualitative means of explaining the effects that perturbing the oxygen content in La{sub}(1-x)Sr{sub}xMnO{sub}(3±δ) (LSM) cathodes has on their O{sub}2 redox activity and as well as the emergence of pseudo-capacitive characteristics under low pO{sub}2 atmospheres. The Wagner Factor correlates the rate constant of the O{sub}2 redox reaction in mixed conducting perovskites (k{sub}(chem), D{sub}(chem)) to changes in the oxide's oxygen concentration. The emergence of an oxygen under-stoichiometric (3-δ) state under low O{sub}2 partial pressures and/or at high cathodic overpotentials is believed to lead to the observed electrochemical capacitive behavior.