Investigation On Fabrication And Application Of Ceria Electrolyte Films

In this thesis, a simple and effective slurry spin coating approach (as a patent applied by us) was developed for fabricating Sm0.2Ce0.8O1.9 (SDC) films for anode-supported solid oxide fuel cells. And some researches on materials, techniques and theories for SDC film fabrication and property were carried out as well.Glycine-nitrate process (GNP) was used to synthesize SDC powders. XRD patterns show that all SDC powders calcined at various temperatures have a cubic fluorite structure. TEM and SEM results reveal that the SDC sample has such a small crystallite size and high surface energy that it typically forms aggregations. The soft aggregations of the samples could be smashed by ball-milling treatment. And the aggregation property and sintering shrinkage curves of the samples sintered at different temperatures were also investigated.The results of the comparative studies showed that the agglomerate of the SDC powders had a significant effect on the formation of the electrolyte membranes. The excellent sintering ability of the electrolyte membrane made from ball-milled powder is largely due to the high green density of the powders. To avoid cracks or pores of the membrane induced by evaporation of the organics during the co-sintering step, every layer has a baking treatment before spin coating the next layer. When each layer of the coating was baked at 420 oC and the spinning-heating cycles are repeated for 5 times, a dense SDC film with somewhat rough surface was successfully fabricated.Using a Ba0.5Sr0.5Co0.8Fe0.2O3-δ(BSCF)-SDC composite cathode, the cell with a 15μm-thick SDC electrolyte membrane achieved an excellent performance.