Étude de la fabrication de piles à combustible nanostructurées SOFC par l'injection de suspensions et de solutions dans un plasma inductif
Other titre : Nano-structured SOFCS fabrication using solution/suspension induction plasma spray technology
In this work, the nano-structured components of solid oxide fuel cells have been produced, using radio frequency (RF) solution or suspension plasma spraying processes. The emerging technology of suspension plasma spraying was explored to produce thin and gas tight nano-structured solid oxide fuel cells electrolytes, which in an effort to develop a cost-effective and scalable fabrication technique for high performance solid oxide fuel cells (SOFCs). Glycine-nitrate process (GNP) produced cerium oxide (CeO[subscript 2]) and gadolinium oxide (Gd[subscript 2]O[subscript 3]) nano-powders were used to prepare suspensions and then separately injected to form composite GDC electrolyte coatings. A dynamic mask system has been developed to control the heating effects of a high-temperature plasma deposition process. The experimental results of the nano-structured SOFCs GDC electrolytes production by means of a RF suspension plasma spraying process using the newly proposed mask were compared to the ones without mask. The potential of this deposition technique to improve the electrolyte coating uniformity and to reduce the coating porosity was demonstrated. SOFCs anodes require long triple phase boundary (TPB) and appropriate gas diffusion pass for the fast transport of both fuel and exhaust gases, but the area where gas diffusion passes are especially required would be different from the area suitable for electrochemical reaction in the anodes. Functionally graded anodes in both composition and porosity have been proposed to fulfill the anodic functions in adequate anodic areas. On the basis of the optimized spraying conditions and the laboratory-developed solution feeding system, NiO-GDC functionally graded nanostructure anodes were prepared using solution plasma spraying (SolPS) process. Then the microstructure and material composition of the anodes were analyzed. A graded distribution in contents of both nickel and GDC was confirmed in the coating. Field emission scanning electron microscopy (FESEM) observation exhibited a continuous variation in porosity from 35% to 9% along the direction across the coating thickness. The functionally graded anodes deposited by SolPS process may minimize the thermal expansion mismatch between SOFC components and increase the length of triple phase boundary, which should lead to the improvement of the anodic performances. The successful fabrication of the functionally graded nano-structural electrodes as well as dense electrolyte coatings represents an opportunity for the Centre de Recherche en Énergie, Plasma et Électrochimie (CREPE) to fabricate the fully integrated nano-structured SOFC using solution and suspension plasma spraying processes.
- Génie – Thèses