The chemical stability and conductivity of BaCe0.9−xYxNb0.1O3−σ proton-conductive electrolyte for SOFC

BaCe0.8Y0.2O3−δ and BaCe0.9−xYxNb0.1O3−δ (x = 0.1, 0.15, 0.2, 0.25, 0.3, 0.35) were prepared by a solid-state reactions. It was found that the BaCe0.8Y0.2O3−δ samples decomposed into CeO2 and BaCO3 after being exposed in the atmosphere (3% CO2 + 3% H2O + 94% N2) at 700 °C for 10 h. However, samples containing Nb remains unchanged in the same conditions, demonstrating a better stability in the presence of CO2 and H2O. The conductivity of BaCe0.9−xYxNb0.1O3−δ increased with the increase of Y content (x ≤ 0.30), and the highest value was observed at x = 0.30 where a significant decrease in conductivity took place at x = 0.35. The conductivity of BaCe0.6Y0.3Nb0.1O3−δ reaches 0.01 S/cm in humid hydrogen at 700 °C, slight lower than BaCe0.8Y0.2O3−δ, 0.012 S/cm in the same conditions. Fuel cell with BaCe0.6Y0.3Nb0.1O3−δ as-prepared was successfully prepared and humidified hydrogen was supplied as fuels in evaluating the fuel cell performance. The open circuit voltage, peak power density and interfacial resistance at 700 °C were 1.02 V, 345 mW/cm2 and 0.27 Ω cm2, respectively.