Journal of Power Sources, Vol.245, 377-388, 2014
A bottom-up building process of nanostructured La0.75Sr0.25Cr0.5Mn0.5O3-delta electrodes for symmetrical-solid oxide fuel cell: Synthesis, characterization and electrocatalytic testing
Pure-phase La0.75Sr0.25Cr0.5Mn0.5O3-delta (LSCM) nanocrystallites have been successfully synthesized by the combustion method, employing glycine as fuel and complexing agent, and ammonium nitrate as combustion trigger. A detailed morphological and structural characterization is performed, by using of X-ray diffraction, N-2 physisorption and electron microscopy. The LSCM material consists in interconnected nanocrystallites (similar to 30 nm) forming a sponge-like structure with meso and macropores, being its specific surface area around 10 m(2) g(-1). Crystalline structural analyses show that the LSCM nanopowder has trigonal/rhombohedral symmetry in the R-3c space group. By employing the spin coating technique and quick-stuck thermal treatments of the ink-electrolyte, electrodes with different crystallite size (95, 160 and 325 nm) are built onto both sides of the La0.8Sr0.2Ga0.8Mg0.2O3-delta-disk electrolyte. To test the influence of the electrode crystallite size on the electrocatalytic behavior of the symmetrical cells, electro-chemical impedance spectroscopy measurements at 800 degrees C were performed. When the electrode crystallite size becomes smaller, the area specific resistance decreases from 3.6 to 1.31 0 cm(2) under 0.2O(2) -0.8Ar atmosphere, possibly due to the enlarging of the triple-phase boundary, while this value increases from 7.04 to 13.78 Omega cm(2) under 0.17H(2)-0.03H(2)O-0.8Ar atmosphere, probably due to thermodynamic instability of the LSCM nanocrystallites. (C) 2013 Elsevier B.V. All rights reserved.