Investigation of the necessity to apply a (Ce, Gd)O2 interlayer between the low-temperature processed (La, Sr)CoO3 electrode film and the (Zr, Y)O2 electrolyte in solid oxide fuel cells

Official URL: https://dx.doi.org/10.1016/j.ssi.2022.116030

Gadolinia doped ceria (GDC) interlayers have been widely used to avoid resistive phase formation at the mixed ionic electronic conductor (MIEC) (La,Sr)CoO3 (LSC) air electrode/ yttria stabilized zirconia (YSZ) electrolyte interfaces. Although MIEC electrodes fabricated by low-temperature metal organic precursor methods offer the highest electrochemical performance, no studies exist on the effect of GDC interlayer on their performance. In this work, we investigated the necessity for a GDC interlayer between the low-temperature processed LSC electrode and the YSZ electrolyte. Through x-ray diffraction, scanning transmission electron microscopy/energy-dispersive x-ray spectroscopy and x-ray photoelectron spectroscopy analyses, we studied the impact of the GDC interlayer on i) the formation of resistive zirconate phases at the LSC/YSZ interface and ii) the overall phase and surface chemistry evolution. While no resistive zirconate phases formed in the LSC/YSZ system due to low processing temperatures, La leaching into the GDC layer altered the overall phase evolution, in addition to the resulting cation stoichiometry. This LSC/GDC/YSZ system showed a polarization resistance improved by an order of magnitude, attributable to the changes in phase composition.