Oxygen Reduction Kinetics and Transport Propertiesof (Ba,Sr)(Co,Fe)O_(3-δ) and Related SOFC Cathode Materials

摘要

Oxygen surface reduction kinetics is studied with the help ofimpedance spectra measured on dense thin film microelectrodes of(Ba_(1-x)Sr_x)(Co_(1-y)Fe_y)O_(3-δ) (BSCF) and related SOFC cathodematerials. Effective oxygen exchange rate constants k~q, calculatedfrom area-specific surface resistances Rs extracted from theimpedance spectra, increase in the sequence of LSM(La_(1-x)Sr_xMnO_(3±δ)), LSCF (La_(1-x)Sr_xCo_(1-y)FeyO_(3-δ)) and BSCF. Theinfluence of bulk properties, such as electronic conductivity andGoldschmidt tolerance factor, on k~q is investigated to supplyinformation for identifying the rate-determining step. Possibleroles of oxygen vacancies in the oxygen surface incorporationreaction are discussed.