Abstract
InBaCo4-xZnxO7 oxides have been synthesized and characterized as cathode materials for intermediate temperature solid oxide fuel cells (IT-SOFC). The effect of Zn substitution for Co on the structure, phase stability, thermal expansion, and electrochemical properties of the InBaCo4-xZnxO7 has been investigated. The increase in the Zn content from x = 1 to 1.5 improves the high temperature phase stability at 600 oC and 700 oC for 100 h, and chemical stability against a Gd0.2Ce0.8O1.9 (GDC) electrolyte. Thermal expansion coefficient (TEC) values of the InBaCo4-xZnxO7 (x = 1, 1.5, 2) specimens were determined to be 8.6 × 10-6 – 9.6 × 10-6 /oC in the range of 80 – 900 oC, which provides good thermal expansion compatibility with the standard SOFC electrolyte materials. The InBaCo4-xZnxO7 + GDC (50:50 wt. %) composite cathodes exhibit improved cathode performances compared to those obtained from the simple InBaCo4-xZnxO7 cathodes due to the extended triple-phase boundary (TPB) and enhanced oxide-ion conductivity through the GDC portion in the composites.
