A cobalt-free SrFe_0.9Sb_0.1O_3-δ cathode material for proton-conducting solid oxide fuel cells with stable BaZr_0.1Ce_0.7Y_0.1Yb_0.1O_3-δ electrolyte

A cobalt-free cubic perovskite oxide SrFe_0.9Sb_0.1O_3-δ (SFSb) is investigated as a novel cathode for proton-conducting solid oxide fuel cells (H-SOFCs). XRD results show that SFSb cathode is chemically compatible with the electrolyte BaZr_0.1Ce_0.7Y_0.1Yb_0.1O_3-δ (BZCYYb) for temperatures up to 1000 °C. Thin proton-conducting BZCYYb electrolyte and NiO-BaZr_0.1Ce_0.7Y_0.1Yb_0.1O_3-δ (NiO-BZCYYb) anode functional layer are prepared over porous anode substrates composed of NiO-BZCYYb by a one-step dry-pressing/co-firing process. Laboratory-sized quad-layer cells of NiO-BZCYYb/NiO-BZCYYb/BZCYYb/SFSb are operated from 550 to 700 °C with humidified hydrogen (∼3% H₂O) as fuel and the static air as oxidant. An open-circuit potential of 0.996 V, maximum power density of 428 mW cm^-2, and a low electrode polarization resistance of 0.154 Ω cm² are achieved at 700 °C. The experimental results indicate that the cobalt-free SFSb is a promising candidate for cathode material for H-SOFCs.