Double perovskite La1.8Sr0.2CoFeO5+δ as a cathode material for intermediate temperature solid oxide fuel cells

Abstract Double perovskite La1.8Sr0.2CoFeO5+δ (DP-LSCF) is prepared by a modified sol-gel method and investigated as a cathode material for intermediate temperature solid oxide fuel cells (IT-SOFCs, 600–850 °C). The compound is characterised by a variety of techniques, including TG/DTA, X-ray diffraction, Raman spectroscopy, X-ray photoelectron spectroscopy and SEM-EDS. The formation of the double perovskite structure with rhombohedral symmetry after its calcination at 1000 °C for 6 h is revealed by X-ray diffraction. Excellent chemical compatibility with a Ce0.9Gd0.1O1.95 (GDC) electrolyte is found. The double perovskite structure is confirmed by Raman and X-ray photoelectron spectroscopy. The partial substitution of Fe cations at the Co site affects the physical-chemical properties of DP-LSCF. Compared with other double perovskite materials based on Co, DP-LSCF shows a lower thermal expansion coefficient (19.4 × 10−6 K−1). The compound exhibits semiconductor behaviour and an area specific resistance of 0.42 Ω cm2 at 800 °C when GDC is employed as the electrolyte. These results suggest that DP-LSCF is a promising cathode material for IT-SOFC applications.