Novel cobalt‐free family of SrFe 1‐x Sc x O 3 ‐δ perovskite materials for cathode applications in solid oxide fuel cells

Summary Perovskites of composition SrFe 1‐x Sc x O 3‐δ (x = 0.05, 0.1, 0.2) were elaborated, characterized, and tested in solid‐oxide fuel cells (SOFC) as cathode materials. Porous materials were obtained by a solid‐state route. Thermogravimetric studies showed that the oxides eliminate oxygen as temperature increases. Neutron powder diffraction (NPD) experiments unveils that, at 800°C, the crystallographic structure of SrFe 0.9 Sc 0.1 O 3‐δ contains δ = 0.51 (2) vacancies at oxygen sites, located at random in the cubic unit cell. The oxygen vacancies are essential for the oxygen diffusion, which is prerequisite for a MIEC‐type cathode. The electronic conductivity σ exhibits an insulator‐to‐metal transition at 420°C, reaching almost 200 S cm −1 for x = 0.05; σ was found to decrease as the Sc content increases. The cell performance was tested on electrolyte supported single cells, with LSGM electrolyte, fed by pure H 2 . The maximum power density reached by the Sc‐ferrite (x = 0.05) was of 340 mW cm −2 at 800°C.