From theory to experiment: BaFe0.125Co0.125Zr0.75O3−δ, a highly promising cathode for intermediate temperature SOFCs

Abstract

In a recent theoretical study [Jacobs et al., Adv. Energy Mater., 2018, 8, 1702708], BaFe_0.125Co_0.125Zr_0.75O_3−δ was predicted to be a stable phase with outstanding performance as an auspicious cathode for intermediate-temperature solid oxide fuel cells (IT-SOFCs). It is shown here that the theoretical predictions are valid. The material can be synthesized by the citrate method as a single cubic Pmm phase with a significant amount of oxygen vacancies, randomly distributed in the anionic sublattice facilitating oxygen vacancy conduction. A thermal expansion coefficient of 8.1 × 10⁻⁶ K⁻¹ suggests acceptable compatibility with common electrolytes. Electrochemical impedance spectroscopy of symmetrical cells gives an area-specific resistance of 0.33 Ω cm² at 700 °C and 0.13 Ω cm² at 800 °C. These values are reduced to 0.13 Ω cm² at 700 °C and 0.05 Ω cm² at 800 °C when the material is mixed with 30 wt% Ce_0.9Gd_0.1O_2−δ.