Potentiality of cobalt-free perovskite Ba0.5Sr0.5Fe0.9Mo0.1O3−δ as a single-phase cathode for intermediate-to-low-temperature solid oxide fuel cells

Cobalt-free perovskite Ba0.5Sr0.5Fe0.9Mo0.1O3−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 BaZr0.1Ce0.7Y0.1Yb0.1O3−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.