Quantifying the Relationship Between Microstructure and Performance in Gadolinium-Doped Ceria Infiltrated Ni/YSZ Symmetric Cells

Infiltration of mixed ionic/electronic conducting nanocatalysts into the anodes of solid oxide fuel cells allows the hydrogen oxidation reaction to occur at double-phase boundaries (DPBs) rather than being confined only to the triple-phase boundaries (TPBs). In this research, we use a combination of cross-sectional scanning electron microscopy, three-dimensional (3D) reconstruction, and electrochemical methods to characterize both baseline and gadolinium-doped ceria (GDC)-infiltrated symmetric cells, with the goal of establishing a comparison between the density of electrochemically active sites in uninfiltrated and GDC-infiltrated cells. Electrochemical impedance spectroscopy and distribution of relaxation times analysis showed GDC infiltration decreased the overall polarization of the anode by a factor of 8.78× and decreased the resistance associated with the reactions at the TPBs/DPBs by a factor of over 21×. By quantifying expected GDC deposition morphology in the Ni/YSZ anode, it is estimated that reactions occur in the baseline cell up to 84 nm from the active TPB lines.