Ba0.5Sr0.5Zn0.2Fe0.8O3-δ-BaCe0.5Zr0.3Y0.16Zn0.04O3-δ composite cathode for proton-conducting solid oxide fuel cells

A stable, easily sintered perovskite oxide BaCe0.5Zr0.3Y0.16Zn0.04O3-δ (BCZYZ) as electrolyte for proton-conducting solid oxide fuel cells with Ba0.5Sr0.5Zn0.2Fe0.8O3-δ-BaCe0.5Zr0.3Y0.16Zn0.04O3-δ (BSZF-BCZYZ) composite cathode was investigated. Thin proton-conducting BCZYZ electrolyte was prepared over porous anode substrate composed of NiO-BCZYZ by the one-step dry-pressing/co-firing method. A laboratory-sized tri-layer cell of NiO-BCZYZ//BCZYZ (∼21 μm)/BSZF-BCZYZ (∼32 μm) was operated from 550 to 700 deg. C with humidified hydrogen (∼3% H2O) as fuel and the static air as oxidant. The BCZYZ perovskite electrolyte synthesized by a modified Pechini process was completely dense after sintered at 1250 deg. C for 5 h, lower than that without Znic dopant about 150 deg. C. An open-circuit potential of 1.007 V, a maximum power density of 387 mW cm-2, and a low polarization resistance of the electrodes of 0.11 Ω cm2 were achieved at 700 deg. C.