Design and Characterization of Functionally Graded Cathode Materials For Solid Oxide Fuel Cells

This work presents results on synthesis and characterization of mixed ionic-electronic conducting nanocomposite cathode materials for Intermediate Temperature Solid Oxide Fuel Cells. The corresponding materials are comprised of La0.8Sr0.2MnO3 (LSM) or La0.8Sr0.2Fe1-xNixO3-delta (x= 0.1-0.4) (LSFNx) perovskites and Sc0.1Ce0.01Zr0.89O2-x (ScCeSZ) or Ce0.9Gd0.1O2-delta (GDC) fluorites mixed via powerful ultrasonic dispersion of powders in isopropanol. Genesis of their structural properties was studied in detail by transmission electron microscopy with elemental analysis and X-ray diffraction; surface features were characterized by X-ray Photoelectron Spectroscopy. Perovskite-fluorite nanodomain interfaces appear to provide a path for fast oxygen diffusion as revealed by the oxygen isotope exchange and temperature-programmed desorption. Testing in wet H-2/air for button-size fuel cells with thin Y-doped zirconia layer and nanocomposite functionally graded cathodes demonstrated promising and stable performance in some combinations in the intermediate temperature range.