Influence of CO2 on the Cathode Performance and Stability of La1-XSrxCo0.2Fe0.8O3-δ in Solid Oxide Fuel Cells

La_1-xSr_xCo_0.2Fe_0.8O_3-δ is a high performance cathode material due to its mixed ionic and electronic conducting behavior that has widely been in used in solid oxide fuel cells (SOFCs). It has been shown that Sr segregates out of the lattice to the surface of the material and creates new phases in forms of SrO and SrCO₃. Even though these surface phases are known to be insulators, their effects on oxygen surface exchange, oxygen transport, and on the overall cell performance remain as open questions.

In order to address the above issues, electrochemical impedance spectroscopy (EIS) was used to study cathode performance on cells of the configuration La_1-xSr_xCo_0.2Fe_0.8O_3-δ (LSCF)/ gadolinium-doped ceria (GDC) barrier electrolyte layer/ yttria-stabilized zirconia (YSZ) electrolyte/porous (La_0.8Sr_0.2)_0.95MnO₃-YSZ counter electrode. LSCF performance was investigated in a dual atmosphere set up in CO₂–free air and in the presence of CO₂ at the intermediate operational temperature range of 600-800°C as a function of time.