The chemical stability and conductivity of BaCe{sub 0.9-x}Y{sub x}Nb{sub 0.1}O{sub 3-{sigma}} proton-conductive electrolyte for SOFC

BaCe{sub 0.8}Y{sub 0.2}O{sub 3-{delta}} and BaCe{sub 0.9-x}Y{sub x}Nb{sub 0.1}O{sub 3-{delta}} (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 BaCe{sub 0.8}Y{sub 0.2}O{sub 3-{delta}} samples decomposed into CeO{sub 2} and BaCO{sub 3} after being exposed in the atmosphere (3% CO{sub 2} + 3% H{sub 2}O + 94% N{sub 2}) at 700 deg. C for 10 h. However, samples containing Nb remains unchanged in the same conditions, demonstrating a better stability in the presence of CO{sub 2} and H{sub 2}O. The conductivity of BaCe{sub 0.9-x}Y{sub x}Nb{sub 0.1}O{sub 3-{delta}} 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 BaCe{sub 0.6}Y{sub 0.3}Nb{sub 0.1}O{sub 3-{delta}} reaches 0.01 S/cm in humid hydrogen at 700 deg. C, slight lower than BaCe{sub 0.8}Y{sub 0.2}O{sub 3-{delta}}, 0.012 S/cm in the same conditions. Fuel cell with BaCe{sub 0.6}Y{sub 0.3}Nb{sub 0.1}O{sub 3-{delta}} 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 deg. C were 1.02more » V, 345 mW/cm{sup 2} and 0.27 {Omega} cm{sup 2}, respectively.« less