Study On The Preparation Methods Of Nanocrystalline Powders And Thin Films Used For Sofcs Electrolyte

Over the past years, solid oxide fuel cells (SOFCs) whose merits are clean, efficient and environmental-friendly, have attracted great attention for their use in the direct conversion of chemical energy into electrical energy through electrochemical reaction. Due to its excellently chemical and thermal stability, mechanical properties and nearly pure oxygen ionic conductivity, yttria-stabilized zirconia (YSZ) has been actively investigated and applied in widely technical fields. YSZ is the most commonly and potentially used as an electrolyte material for the intermediate and high temperatures (700-1000oC) SOFCs. It is one of the most promising methods currently to reduce the fabrication cost and prompt SOFCs commercially that modifies YSZ and makes it suitable for an SOFC electrolyte film material operating at intermediate temperatures. In this study, nanocrystalline powders were used as starting material to explore the fabrication technique of electrolyte membrane, whose aims are to lower the fabrication cost, and to greatly improve the output performances of SOFCs based on YSZ electrolyte films. The main contents of this dissertation are as follows: On the one hand, based on diverse preparation techniques, nanocrystalline YSZ and nanocrystalline NiO powders were synthesized and characterized, and the reaction mechanism was studied. For comparison, the properties, especially the resulting electrical properties of the nanocrystalline YSZ obtained from different synthesis processes and the sintered samples from different powders calcinations temperature were studied, and the change regularities of the performances were obtained. On the other hand, the prepared nanocrystalline powders were used as the starting materials to explore alterative membrane preparing techniques whose methods are cost-effective, easy, simple, as well as high quality and efficiency of the membranes. This dissertation developed a simple and cost-effective approach to fabricate electrolyte thin films using filter-coating technique, and reported our initial results to fabricate YSZ electrolyte thin films with a modified dry pressing method. The single cell was fabricated from the two films preparing techniques and the corresponding cell performance was studied.Four powders synthesis routes, namely homogeneous precipitation, ammonium...