| Solid oxide fuel cells (SOFCs) produce electrical power at efficiencies greater than 60% with virtually no pollution. Unfortunately, due to ohmic losses in the oxygen ion conducting electrolyte and electrodes at low temperatures, these cells are limited to high operation temperatures. Recent studies have shown that the use of thin film electrolytes can greatly reduce several problems associated with the high operation temperatures of these devices such as mechanical and chemical degradation as well as reducing the cost of operation and of the cell component materials. Cost-effective and production-scalable processing routes for the production of fully dense thin films on porous substrates must be developed in order to make these devices marketable. The subject of investigation was to produce thin films on porous substrates via spin coating and develop techniques for adequately characterizing their electrical and microstructural properties. It was found that fully dense electrolytes on porous substrates can be produced from polymeric precursors using a wide variety of techniques. It is proposed that a thin film processing technique involving a colloidally deposited porous interfacial layer and a polymeric precursor processed electrolyte has the best possibility for both reliability and ease of processing of thin film SOFCs. Characterization of these materials' microstructural properties can be accomplished with great care using a variety of techniques. Using a technique developed during the processing of thin film SOFCs, it is also illustrated that fully dense oxide thin films can be produced on polymeric substrates at temperatures less than 400°C. These structures should have a wide range of applications in everything from dielectrics to flexible, transparent conductors to thermal insulators. |
