| The purpose of this dissertation is to further the understanding of polarization effects in solid oxide fuel cells. Three main problems are addressed:; First the dependence of polarization on various cell parameters was studied. The parameters investigated were: (1) YSZ electrolyte thickness, (2) cathode interlayer thickness, (3) anode support thickness, and (4) anode support porosity. Dependence of cell performance on various parameters was rationalized on the basis of a simple analytical model. Second, the effect of morphology and space charge on conduction of porous bodies was investigated. In this study, a simple, one-dimensional model of the role of connectivity on electrical conductivity of porous bodies, including the roles of grain boundaries and space charge, was developed. To investigate the space charge effect on cell performance, a leaching process was used to fabricate porous electrolytes. Electrochemical characterization of single cells shows that the space charge has a significant effect on cell performance. Finally, a method based on combustion synthesis for preparing nanocrystalline powders was investigated. |
