Nature and Functionality of Oxygen/Cathode/Electrolyte-Interfaces in SOFCs

The functionality of oxygen electrodes for solid oxide fuel cells (SOFC) is mainly determined by intrinsic material properties and fabrication controlled microstructure parameters for an enhanced oxygen reduction reaction at the solid/gas interface. La1-xSrx Co1-yFeyO3-δ (LSCF) delivers high oxygen-exchange kinetics and is widely used as a cathode material for high performing anode-supported fuel cells. LSCF is however chemically instable against Zr-based electrolytes (f.e. Y stabilized ZrO2 - YSZ) and is therefore separated by a 5-8 µm thick diffusion barrier interlayer, consisting of rare earth doped Cerium oxide (f.e. doped with Gd - GDC). This study shows that variations in GDC manufacturing conditions tremendously influence the cathode performance. The LSCF-GDC-YSZ layer sequence reveals a complex interacting nature during fabrication that needs to be understood for further optimization and reproducible performance of the oxygen/cathode /electrolyte interface in SOFCs.