A novel cobalt-free double-perovskite NdBaFe1.9Nb0.1O5+δ cathode material for proton-conducting IT-SOFC

A novel cobalt-free double-perovskite oxide NdBaFe1.9Nb0.1O5+δ (NBFNb10) was prepared by a solid-state reaction method and investigated as a suitable cathode material for intermediate temperature solid oxide fuel cells (IT-SOFCs). It was discovered that partial substitution of Nb for Fe-site further enhanced the electrical conductivity of NdBaFe2O5+δ (NBF). The NBFNb10 exhibited the highest conductivity of 109 S cm−1 at 300–800 °C in air, and showed good chemical compatibility with the BaZr0.1Ce0.7Y0.2O3−α (BZCY) electrolyte. A single cell with the NBFNb10–BZCY composite cathode and NiO–BZCY composite anode-supported BZCY electrolyte membrane (ca. 30 μm thickness) was fabricated and tested at 500–700 °C using H2 as fuel and air as oxidant. The peak power density and the interfacial polarization resistance (Rp) were 392 mW cm−2 and 0.14 Ω cm2 at 700 °C, respectively.