Ba0.9Co0.5Fe0.4Nb0.1O3−δ as novel oxygen electrode for solid oxide electrolysis cells

A novel perovskite oxide Ba0.9Co0.5Fe0.4Nb0.1O3−δ (BCFN) was prepared and characterized as oxygen electrode for solid oxide electrolysis cells (SOECs) using La0.8Sr0.2Ga0.83Mg0.17O3−δ (LSGM) as electrolyte. Symmetrical half-cell study shows that the polarization resistance of BCFN is only 0.08 Ω cm2 at 750 °C in air. Electrochemical impedance spectra and voltage-current curves of the electrolysis cell with the configuration of BCFN|LSGM|La0.4Ce0.6O2−x|Ni–Ce0.9Gd0.1O1.95 were measured as a function of operating temperature and steam concentrations to characterize the electrolysis cell performances. Under an applied electrolysis voltage of 1.5 V, the maximum consumed current density increased from 0.835 A cm−2 at 700 °C to 3.237 A cm−2 at 850 °C with 40 vol.% absolute humidity (AH), and the hydrogen generation rate of the cell can be up to 1352 mL cm−2 h−1 with 40 vol.% AH at 850 °C. Further, the electrolysis cell has showed very stable performance during a 200 h short-term electrolysis testing, indicating that BCFN can be a very promising candidate for the oxygen electrode of SOECs using LSGM electrolyte.

► Polarization resistance of Ba0.9Co0.5Fe0.4Nb0.1O3−δ oxygen electrode is only 0.08 Ω cm2 at 750 °C. ► At 1.5 V, the maximum consumed current density is 3.237 A cm−2 at 850 °C with 40 vol% absolute humidity. ► Hydrogen generation rate can be up to 1352 mL cm−2 h−1 with 40 vol% absolute humidity at 850 °C. ► The electrolysis cell showed stable performance during a 200 h short-term electrolysis testing.