Sm0.5sr0.5coo3-Delta Surface Modification Of La0.6sr0.4co0.2fe0.8o3-Delta-Ce(0.9)Gd0.1(2-Delta) Composite Oxygen Electrodes For Solid Oxide Electrochemical Cells

La0.6Sr0.4Co0.2Fe0.8O3-delta-Ce0.9Gd0.1O2-delta (LSCF-GDC) composite oxygen electrodes have been widely used in intermediate temperature (<700 degrees 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 Sm0.5Sr0.5CoO3-delta (SSC) infiltrated LSCF-GDC electrodes. The LSCF-GDC polarization resistance increases by similar to 5 times over similar to 1000 h at 650 degrees 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.