Optimization of Micro-SOFC Performance through the Control of the Architecture Using a Low Cost Process

International audienceMicro-SOFCs (μSOFCs) have been attracting much attention because of reducing operating temperature, their potential as long lasting, rapid re-charging, lightweight portable power sources. They have been demonstrated to exhibit good power density at temperatures as low as 600°C. To be cost competitive and relevant for widespread use, it is crucial to explore the synthesis of thin film via soft-chemistry less expensive than physical ones (PLD, ALD...). Combining dip-coating and sol-gel processes, nanometer scale 10%gadolinium doped ceria (GDC, electrolyte), LSCF (cathode) and 10%GDC-nickel based composite nanoarchitectures films were deposited on a Si wafer and on porous Al2O3 substrates in one-step thermal processing. For the electrodes, the 3-D network is constituted of non-agglomerates nanoparticles of Gd-doped ceria and NiO or LSCF. In this arrangement, particles in the nanoscale are kept because of the presence of secondary phases (NiO, LSCF) and pores. The different interfaces in these hierarchical-porous composites tune the particles size as well as the surface energy. The study of the microstrain through XRD analyses shows that the domain of stability of the studied microstructure is large (200°C) for NiO/GDC cermet. Accordingly, the effect of the microstructure on the mixed ionic conductivities in this range of temperature is low, because their microstructure is stable. These composites can be used as model for understanding the impact of the size of the particle on the transport of ions and electrons. Furthermore, the reduction of the NiO/GDC electrodes were studied through various techniques: XRD, ac-impedance. The microstructures were stable up to temperatures of 600°C. The electrochemical performances I-V curves of these different thin layers were measured in a single gas atmosphere setup. The electrochemical results will be discussed as function of the cathode and anode composition and the microstructure (the temperature and the reducing treatments). Finally, these different hierarchical-porous thin films are favorable for efficient composite electrode and electrolyte for micro-SOFC application. 1. A. Evans et al., Journal of Power Sources, 2009, 194, 119-129. 2. J. Hierso, O. Sel, A. Ringuede, C. Laberty-Robert, L Bianchi, D. Grosso, and C. Sanchez, Chem. Mater. 2009, 21, 2184-2192 3. G. Muller, G. Baldinozzi, C. Laberty-Robert, C. Sanchez, 2011, submite