Ln(Sr,Ca)_3(Fe,Co)_3O_(10) Intergrowth Oxide Cathodes for Solid Oxide Fuel Cells

摘要

The perovskite-related intergrowth oxides Ln(Sr,Ca)_3(Fe.Co)_3O_(10). which belong to the n = 3 member of the Ruddlesden-Popper (R-P) series, have been explored as cathodes in solid oxide fuel cells (SOFC). The effects of cationic substitutions for Sr and Fe on the crystal chemistry, thermal properties, and electrochemical performances in SOFC have been investigated. The electrical conductivity, thermal expansion coefficient (TEC), and cathode performance increase with the substitution of Co for Fe. For instance, the LaSr_3Fe_(3-x)Co_xO_(10)(LSFC) cathode composition shows electrochemical performances comparable to that of the well-known perovskite cathode La_(0.6)Sr_(0.4)CoO_3. Further improvement in the cathode performance and a decrease in TEC have been realized by a substitution of less electropositive Ca for Sr in NdSr_(2.5)Ca_(0.5)Fe_(1.5)Co_(1.5)O_(10) (NSCFC). The improved performance of NSCFC is attributed to the decreased lattice dislortion in the perovskite layer, which is beneficial to enhance the oxide-ion conductivity.