Ceramic Deposition of Electrolyte Layer for Large Area SOFC

Solid Oxide Fuel Cells are promising devices for electricity generation for their high efficiency, fuel flexibility and modularity. Shaping processes able to considerably reduce the manufacturing costs are however required to bring the SOFC technology to the market. The overall processing of these devices has to become as simple and cost effective as possible in order to reduce the cost connected to the production of both the single layer and the entire device. Although the supporting elements are commonly produced by tape casting, several different techniques have been explored for the production of the thin electrolyte layer. The production of a dense electrolyte is the key point to assure high electrochemical performances to the entire cell. The work addresses the main issues connected to the production of a dense YSZ electrolyte layer onto a NiO-YSZ supporting anode with three of the most common and easy scalable ceramic deposition processes: tape casting, screen printing and wet powder spray. The influence of the nature of the deposition process on the tape formulation and thermal treatments of the green bilayer are studied and compared. The requirements needed to obtain a camber-free large area half-cell are examined and deeply described. A careful optimization of the process parameters and sintering set-up allows the production of flat cells with well sintered electrolyte with all the techniques proposed.