Fabrication and Characterization of High‐Conductivity Bilayer Electrolytes for Intermediate‐Temperature Solid Oxide Fuel Cells

A stable bilayer electrolyte with high ionic conductivity was developed for intermediate‐temperature solid oxide fuel cell operation. The bilayer structure improved the limited thermodynamic stability of bismuth oxides and prevented electronic conductivity of ceria‐based oxides in reducing atmosphere. Bilayer electrolytes were formed by depositing thin and thick layers of erbia‐stabilized bismuth oxide (ESB) on samaria‐doped ceria (SDC) substrates, via pulsed laser deposition and dip‐coating techniques. Scanning electron microscope (SEM) images of the ESB/SDC samples showed dense ESB layers and excellent adherence between both ESB and SDC phases. Interdiffusion between the two phases was not detected by X‐ray diffraction and EDX. Measurements of the conductivity of SDC coated with ESB exhibited slightly higher total conductance than SDC.