Design of a reduction-resistant Ce0.8Sm0.2O1.9 electrolyte through growth of a thin BaCe1-xSmxO3-alpha a layer over electrolyte surface

A method that can block off electronic current through a samaria-doped ceria (SDC, Ce0.8Sm0.2O1.9) electrolyte is proposed. A thin BaCeO3-based layer 12 mu m thick was grown by a solid-state reaction of the electrolyte substrate and a BaO film deposited previously over the substrate surface at 1500 degrees C. A homogeneous junction between the layer and the electrolyte was formed, thus allowing no delamination and cracking of the layer. Tolerance of this layer to CO2 was high enough to suppress decomposition into BaCO3 and CeO2. Open-circuit voltages of a hydrogen-air fuel cell with the coated SDC electrolyte were near 1 V or more in the range of 600-950 degrees C. The resulting peak power density was higher than that of a fuel cell with an uncoated SDC electrolyte. (C) 2004 The Electrochemical Society.