(Invited) Effects of PrOx and Gd-Doped CeOx Infiltration: Enhancement of Solid Oxide Cell Performance and Stability

PrO x -infiltrated oxygen electrodes can yield relatively low polarization resistances even at reduced operating temperature. Similarly, Gd-doped Ceria (GDC) infiltration into Ni-YSZ fuel electrodes has been shown to reduce polarization resistance while also helping to maintain stable electrolysis operation. Here we review the literature on these electrodes and discuss recent results on electrochemical impedance spectroscopy (EIS) studies of PrO x -infiltrated La0.6Sr0.4Co0.2Fe0.8O3 (LSCF) and SrTi0.3Fe0.55Co0.15O3 (STFC) oxygen electrodes and GDC-infiltrated Ni-YSZ. Physically-based equivalent circuit models are developed using the distribution of relaxation times method and used to fit the symmetric cell EIS data, comparing PrO x - and GDC-infiltrated electrodes with un-infiltrated electrodes. The results suggest that PrO x improves oxygen dissociative adsorption/desorption, oxygen surface exchange, and transport of oxygen in the perovskites; while GDC reduces the reaction resistance associated with three-phase boundaries and improves oxygen transport in Ni-YSZ. Full cells employing the PrO x -infiltrated STFC and Ni-YSZ:GDC electrodes achieve high performance (e.g. fuel cell power density nearly 3 W/cm 2 at 750 o C and > 1 W/cm 2 at 600 o C; and electrolysis current density at 1.3 V of nearly 4 A/cm 2 at 750 o C), while exhibiting promising stability. Combining the equivalent circuit models from the symmetric cell data for each electrode provides a detailed explanation and fit of the full cell EIS results.