Double-perovskites YBaCo2−xFexO5+δ cathodes for intermediate-temperature solid oxide fuel cells

Double-perovskites YBaCo2−xFexO5+δ (YBCF, x = 0.0, 0.2, 0.4 and 0.6) are synthesized with a solid-state reaction and are assessed as potential cathode materials for utilization in intermediate-temperature solid oxide fuel cells (IT-SOFCs) on the La0.9Sr0.1Ga0.8Mg0.115Co0.085O2.85 (LSGMC) electrolyte. The YBCF materials exhibit chemical compatibility with the LSGMC electrolyte up to a temperature of 950 °C. The conductivity of the YBCF samples decreases with increasing Fe content, and the maximum conductivity of YBCF is 315 S cm−1 at 325 °C for the x = 0.0 sample. A semiconductor–metal transition is observed at about 300–400 °C. The thermal expansion coefficient of the YBCF samples increases from 16.3 to 18.0 × 10−6 K−1 in air at temperatures between 30 and 900 °C with increase in Fe content. The area-specific resistances of YBCF cathodes at x = 0.0, 0.2 and 0.4 on the LSGMC electrolyte are 0.11, 0.13 and 0.15 Ω cm2 at a temperature of 700 °C, respectively. The maximum power densities of the single cells fabricated with the LSGMC electrolyte, Ce0.8Sm0.2O1.9 (SDC) interlayer, NiO/SDC anode and YBCF cathodes at x = 0.0, 0.2 and 0.4 reach 873, 768 and 706 mW cm−2, respectively. This study suggests that the double-perovskites YBCF (0 ≤ x ≤ 0.4) can be potential candidates for utilization as IT-SOFC cathodes.

Research highlights▶ YBaCo2−xFexO5+δ double-perovskites were developed as cathode materials for IT-SOFCs. ▶ The cathodes were chemical compatibility with LaGaO3-based electrolyte. ▶ The area specific resistances of these cathodes were lower than 0.15 Ω cm2 at 700 °C. ▶ The single cells with these cathodes exhibited higher power densities.