A-site deficient semiconductor electrolyte Sr(1−x)Co(x)FeO(3−δ) for low-temperature (450–550 °C) solid oxide fuel cells

Fast ionic conduction at low operating temperatures is a key factor for the high electrochemical performance of solid oxide fuel cells (SOFCs). Here an A-site deficient semiconductor electrolyte Sr(1−x)Co(x)FeO(3−δ) is proposed for low-temperature solid oxide fuel cells (LT-SOFCs). A fuel cell with a structure of Ni/NCAL-Sr(0.7)Co(0.3)FeO(3−δ)–NCAL/Ni reached a promising performance of 771 mW cm(−2) at 550 °C. Moreover, appropriate doping of cobalt at the A-site resulted in enhanced charge carrier transportation yielding an ionic conductivity of >0.1 S cm(−1) at 550 °C. A high OCV of 1.05 V confirmed that neither short-circuiting nor power loss occurred during the operation of the prepared SOFC device. A modified composition of Sr(0.5)Co(0.5)FeO(3−δ) and Sr(0.3)Co(0.7)FeO(3−δ) also reached good fuel cell performance of 542 and 345 mW cm(−2), respectively. The energy bandgap analysis confirmed optimal cobalt doping into the A-site of the prepared perovskite structure improved the charge transportation effect. Moreover, XPS spectra showed how the Co-doping into the A-site enhanced O-vacancies, which improve the transport of oxide ions. The present work shows that Sr(0.7)Co(0.3)FeO(3−δ) is a promising electrolyte for LT-SOFCs. Its performance can be boosted with Co-doping to tune the energy band structure.