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Porous composite electrodes consisting of normalBi2normalRu2normalO7 (BRO7) and normalEr0.4normalBi1.6normalO3 (ESB20) were synthesized and characterized using impedance spectroscopy on symmetrical cells. Electrode performance was manipulated compositionally by varying the weight percent of each phase in the composite. Microstructural influences on electrode resistance were examined by varying starting particle sizes of BRO7 and ESB20 powders and using a combination of sedimentation to further reduce particle size and size distributions as well as ultrasonication to break up soft agglomerates. The effect of electrode thickness was also studied by applying successive coats of the electrode inks to the electrolyte substrates. In addition, application of a pure BRO7 current collector was found to dramatically improve performance. Using these optimization techniques, a minimum electrode area specific resistance of 0.03Ωcm2 was attained at 700°C .

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 La0.6Sr0.4Co0.2Fe0.8normalO3−δ -GDC composite cathodes to optimized Bi2Ru2normalO7 -ESB composites. GDC single-layer electrolyte-based SOFCs were prepared from four different fabrications and exhibit maximum power densities ranging from 0.338 to 1.03W/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 1.95W/cm2 and 0.079Ωcm2 total cell ASR was achieved at 650°C for a bilayer cell.

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