SrCo_0.4Fe_0.4Zr_0.1Y_0.1O_3-δ, A new CO₂ tolerant cathode for proton-conducting solid oxide fuel cells

CO₂ poisoning is not a negligible issue for SrCoO_3-δ based materials, which limits their application as cathodes for solid oxide fuel cells (SOFCs). In this paper, iron, zirconium, and yttrium were co-doped into SrCoO_3-δ to form a structurally stable cubic perovskite material, SrCo_0.4Fe_0.4Zr_0.1Y_0.1O_3-δ (SCFZY). The CO₂ adsorption-desorption on SCFZY was studied via X-ray diffraction and CO₂ temperature-programmed desorption. The polarization resistance of the symmetric cell SCFZY|BaZr_0.1Ce_0.7Y_0.1Yb_0.1O_3-δ (BZCYYb)|SCFZY was tested in air containing 10 vol% CO₂ to evaluate the SCFZY's CO₂-tolerance as a SOFCs cathode. When applied as a SOFCs cathode in a cell with a proton-conducting electrolyte BZCYYb, SCFZY showed significant CO₂-tolerance. The single-cell NiO-BZCYYb|BZCYYb|BZCYYb-SCFZY showed an output with a maximum power density of 679 mW cm⁻² at 700 °C and good durability of 500 h. The SCFZY cathode also displayed better CO₂-tolerance than the Ba_0.5Sr_0.5Co_0.8Fe_0.2O_3-δ (BSCF) cathode for IT- SOFCs.