Sm 0.5 Sr 0.5 CoO 3−δ Surface Modification of La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3−δ -Ce 0.9 Gd0.1 2−δ Composite Oxygen Electrodes for Solid Oxide Electrochemical Cells

• Published in: Journal of the Electrochemical Society Vol. 167; no. 16; p. 164504
• Main Authors: Lu, Matthew Y., Yang, Tianrang, Scipioni, Roberto, Chart, Yvonne. A, Furlong, Alexander, Barnett, Scott A.
• Format: Journal Article
• Language: English
• Published: 01.12.2020
• ISSN: 0013-4651; 1945-7111
• DOI: 10.1149/1945-7111/abca6f

La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3− δ -Ce 0.9 Gd 0.1 O 2− δ (LSCF-GDC) composite oxygen electrodes have been widely used in intermediate temperature (<700 °C) solid oxide cells, with composite usually providing better electrochemical performance than single-phase LSCF. However, LSCF-based electrodes are often observed to degrade over time due to Sr segregation. Here we present an impedance spectroscopy study comparing the degradation behaviors of LSCF-GDC and Sm 0.5 Sr 0.5 CoO 3− δ (SSC) infiltrated LSCF-GDC electrodes. The LSCF-GDC polarization resistance increases by ∼5 times over ∼1000 h at 650 °C. In contrast, the SSC-infiltrated electrode shows similar initial polarization resistance but much more stable performance. The impedance modeling results show that the improved stability is associated with the low frequency oxygen dissociative adsorption/desorption process. The results suggest that this adsorption/desorption process slows due to increased Sr segregation on LSCF over time, and that SSC does not degrade significantly due to Sr surface segregation.