The chemical stability and conductivity of BaCe0.9−xYxSn0.1O3−δ solid proton conductor for SOFC

BaCe0.9−xYxSn0.1O3−σ (x = 0.05, 0.1, 0.15, 0.2, 0.25, and 0.3) and BaCe0.8Y0.2O3−δ powders were synthesized by a solid-state reaction method. XRD analysis revealed that the BaCe0.8Y0.2O3−δ powders obviously decomposed into CeO2 and BaCO3 after exposure in 5% H2O + 5% CO2 + 90% N2 at 500 °C for 10 h. However, samples containing Sn remains unchanged in the same conditions, demonstrating a better stability in the presence of CO2 and H2O. The conductivity of BaCe0.9−xYxSn0.1O3−δ increased with the increase of Y content (x ≤ 0.20), and the highest value was observed at x = 0.20 while the conductivity significantly decreases with x = 0.30 and 0.35. And the BaCe0.7Sn0.1Y0.2O3−σ displays 0.01 S/cm at 700 °C in humidified hydrogen. Thin BaCe0.7Sn0.1Y0.2O3−σ electrolyte membranes were prepared through suspension spray combined with in situ sintering at 1400 °C. With Nd0.7Sr0.3MnO3−σ as cathode, solid oxide fuel cells were assembled and tested with humid hydrogen as fuel and static air as oxidant. The OCV, peak output and interfacial resistance were 1.04 V, 220 mW/cm2 and 0.95 Ω cm2 at 700 °C, respectively.