(Invited) Stabilized Bismuth Oxide As a Component in the Air Electrodes of Reversible Solid Oxide Electrochemical Cells

The high ionic conductivity of the high-temperature, cubic phase of bismuth oxide has been recognized for several decades. Significant effort has been directed over the years to stabilize this phase at temperatures of interest for operation of solid oxide electrochemical cells, with Y and Er having emerged as promising substituents to achieve this goal. While stabilized bismuth oxide is not suitable as the membrane material for an electrochemical cell due to its instability under reducing atmospheres, its high conductivity, one to two orders of magnitude greater than that of yttria-stabilized zirconia, renders it attractive as a component in a composite air electrode. Here we describe oxygen electrocatalysis in both random composite structures of yttria-stabilized bismuth oxide (YSB) and lanthanum strontium manganite (LSM) and defined structures with patterned metal electrodes on YSB. The results show that, beyond the high ionic conductivity of YSB, the material provides inherent electrochemical activity for oxygen reduction/evolution reaction.