Effect of SrZrO3 Formation at LSCF-Cathode/GDC-Interlayer Interfaces on the Electrochemical Properties of Solid Oxide Fuel Cells

This work investigates the effect of SrZrO3 formation at cathode- interlayer interfaces on the electrochemical properties of LSCF/GDC/YSZ triplets. Cells consisting of LSCF-cathode/GDC-interlayer/YSZ-electrolyte/Pt-anode were tested under open-circuit voltage (OCV) and galvanostatic condition with a constant current of -0.3 A at 800ºC for 300 h in air. Here the GDC interlayers were grown on polycrystalline YSZ substrates by pulsed laser deposition and fired using a two-step heat treatment at 1400ºC for 1.5 h and 1000ºC for 10 h in air. Both cells showed the formation of nanosized SrZrO3 particles at the LSCF/GDC interface after cell operation. However, the size and distribution of SrZrO3 differ between the OCV and cathodic polarization. Under OCV, the lateral formation of SrZrO3 at the LSCF/GDC interface led to a drastic increase in polarization resistance after long-term operation whereas under cathodic polarization the traverse growth of localized SrZrO3 phase did not cause a deleterious effect on cell performance. From these results, we infer that the depending on the morphology of SrZrO3, its formation may change the oxygen reduction/oxidation reactions at the O2/LSCF/GDC triple-phase boundary (TPB) areas thereby affecting the electrochemical properties of LSCF/GDC/YSZ triplets.