Characterizations of double perovskite Sr2Fe1-xCoxNbO6-δ system as cathode materials for intermediate temperature solid oxide fuel cells (ITSOFCs)

Sr2Fe1-xCoxNbO6-δ (SFCN) (0 {less than or equal to} x {less than or equal to} 0.9) electrode has been prepared by a solid-state reaction. The XRD patterns showed that these materials are single phases with a double perovskite structure. SFCN (x = 0.9) has the highest electrical conductivity among all these composites with = 5.7 S cm-1 at 800 oC. The p-type electronic conduction was dominant in an oxygen partial pressure range of 1-10-15 atm. SEM results showed that the composite electrode formed good contact with Zr0.92Y0.08O2-δ (8YSZ) electrolyte after sintering at 1200 oC for 12 h. Ac impedance spectroscopy and dc polarization measurements were used to study the composite electrode performances in air. The polarization resistance decreased with increasing the Co contents. The area specific resistance (ASR) of SFCN (x = 0.9) was 0.67 ohm cm2 at 800 oC in air. These results suggested that the SFCN composite electrode was a promising cathode material in ITSOFC.