Effect of GDC interlayer thickness on durability of solid oxide fuel cell cathode

Long-term performance degradation of solid oxide fuel cell (SOFC) cathode as a function of gadolinium doped ceria (GDC) interlayer thickness has been studied under accelerated operating conditions. For this purpose, SOFC half-cells with GDC interlayer thicknesses of 2.4, 3.4 and 6.0 µm were fabricated and tested for 1000 h at 900 °C under constant current density of 1 A/cm2. The half-cells consisted of lanthanum strontium cobalt ferrite (LSCF)/GDC composite cathode, GDC interlayer, scandia-ceria stabilized zirconia electrolyte and platinum anode as a counter electrode. Area specific resistance (ASR) of the half-cells was continuously measured over time. Higher increase in ASR was observed for the half-cells with GDC interlayer thickness of 2.4 and 6.0 µm, which is attributed to higher strontium (Sr) diffusion towards electrolyte and to cathode/GDC interface delamination coupled with small Sr diffusion, respectively. However, half-cell with GDC interlayer thickness of 3.4 µm showed smaller degradation rate due to highly dense GDC interlayer which had less interfacial resistance and suppressed Sr diffusion towards electrolyte.