Potentiality of cobalt-free perovskite Ba_0.5Sr _0.5Fe_0.9Mo_0.1O_3-δ as a single-phase cathode for intermediate-to-low-temperature solid oxide fuel cells

Cobalt-free perovskite Ba_0.5Sr_0.5Fe _0.9Mo_0.1O_3-δ (BSFMo) was investigated as a single-phase cathode for intermediate-to-low-temperature solid oxide fuel cells (IL-SOFCs). The X-ray diffraction (XRD) Rietveld refinement, electrical conductivity, thermogravimetric (TG) measurements, the phase reaction were investigated. The doping of high-valence Mo cations into Fe-site obviously enhanced the electrical conductivity of BSFMo sample with the maximum value of 174 S cm^-1. XRD results showed that BSFMo cathode was chemically compatible with the BaZr_0.1Ce_0.7Y_0.1Yb _0.1O_3-δ (BZCYYb) electrolyte for temperatures up to 1000 C. Laboratory-sized tri-layer cells of NiO-BZCYYb/BZCYYb/BSFMo were operated from 550 to 700 C with humidified hydrogen (∼3% H₂O) as fuel and the static air as oxidant, respectively. An open-circuit potential of 1.001 V, the maximum power density of 428 mW cm^-2, and a low electrode polarization resistance of 0.148 Ω cm² were achieved at 700 C. The experimental results indicated that the single-phase BSFMo is a promising candidate as cathode material for IL-SOFCs.