ENGINEERING OF SOLID OXIDE FUEL-CELLS WITH CERIA-BASED ELECTROLYTES

Solid oxide fuel cells that contain mixed ionic-electronic conductors (MIECs) as electrolytes exhibit maximum efficiency at high ionic curre nt density due to a small electronic leakage current. At low ionic cur rent density the electronic current increases due to partial reduction of the electrolyte and efficiency decreases. This leads to restrictio ns in the optimum cell operating range and cell design. Provided the n ecessary materials and cell design parameters are known, the optimum c ell design, especially the electrolyte thickness, can be predicted. Th e optimization of fuel cells with a mixed-conducting ceria electrolyte is outlined. The cell optimization considered in this study includes operating range (V-T), MIEC thickness, and the electrochemical perform ance of the electrodes. Defect chemical considerations predict an opti mum in MIEC thickness depending on the operating temperature.