Development of high performance ceria/bismuth oxide bilayered electrolyte SOFCs for lower temperature operation

This study examines the development of lower temperature solid oxide fuel cells (SOFCs) and the incremental improvement in performance obtained from a wide range of techniques, from pressed anodes to tape-cast anodes, from gadolinia-doped ceria (GDC) single-layer electrolytes to erbium-stabilized bismuth oxide (ESB)/GDC bilayer, and from La_0.6 Sr_0.4 Co_0.2 Fe_0.8 O_3-δ -GDC composite cathodes to optimized Bi₂ Ru₂ O₇ -ESB composites. GDC single-layer electrolyte-based SOFCs were prepared from four different fabrications and exhibit maximum power densities ranging from 0.338 to 1.03 W/ cm² at 650°C. At each fabrication stage, an ESB layer was applied to form a bilayer electrolyte. ESB was deposited by a range of techniques including colloidal deposition and pulsed laser deposition. The result confirms that depending on a fabrication route, the bilayer electrolyte can reduce the total area specific resistance (ASR) 33-49% and increase the maximum power density 44-93%. By using a combination of the materials and fabrication routes, a maximum power density of 1.95 W/ cm² and 0.079 ω cm ² total cell ASR was achieved at 650°C for a bilayer cell.