High-performance Y_(0.9)In_(0.1)BaCo_3(Zn,Fe)O_(7+δ) swedenborgite-type oxide cathodes for reduced temperature solid oxide fuel cells

摘要

With the goal of improving the electrochemical performance while maintaining good phase stability, the Fe-substituted swedenborgite-type Y_(0.9)In_(0.1)BaCo_3Zn_(1-x)Fe_xO_(7+δ) series of oxides have been investigated as cathode materials for solid oxide fuel cells (SOFCs). All the samples with 0 ≤ x ≤ 0.8 were obtained as single-phase oxides with the P31c spAcc group. Both the x = 0 and 0.2 samples were stable after 120 h exposure to 600, 700, and 800 ℃, while the x = 0.6 and 0.8 samples showed instability at 700 and 800 ℃. The x = 0.4 sample was stable at 600 and 800 ℃, but generated a BaCoO_3 impurity phase at 700 ℃. The reversible oxygen absorption tendency of these materials was found to increase with increasing Fe content. Increasing the Fe content in the range of 0 ≤ x ≤ 0.4 was found to reduce the polarization resistance in the Y_(0.9)In_(0.1)BaCo_3Zn_(1-x)Fe_xO_(7+δ) + Gd_(0.2)Ce_(0.8)O_(1.9) composite cathodes, and the x = 0.4 sample was found to have performance superior to that of the well-studied Ba_(0.5)Sr_(0.5)Co_(0.8)Fe_(0.2)O_(3-δ) (BSCF) cathode in the range of 400-700 ℃, making it an attractive cathode candidate for intermediate temperature SOFCs.