Study on Coating Modification of SOEC Oxygen Electrode Material La_0.6Sr_0.1Ba_0.35Co_0.2Fe_0.78Mo_0.02O_3-δ

Solid oxide electrolysis cells hold broad prospects in the field of highly efficient hydrogen production. However, sluggish oxygen evolution reaction kinetics at the oxygen electrode under intermediate-to-low temperatures and strontium (Sr) segregation during long-term operation restrict the enhancement of cell performance. Therefore, in this study, a Ba and Mo co-doped perovskite oxide, La_0.6Sr_0.1Ba_0.35Co_0.2Fe_0.78Mo_0.02O_3-δ (LSBCFM), was employed as the base material to fabricate composite oxygen electrodes. Gd_0.2Ce_0.8O_1.9-δ (GDC) coatings with varying mass fractions (5 wt.%, 10wt.%, and 20 wt.%) were applied via a resonance coating strategy. The effects of the GDC coating amount on the microstructure, phase structure, and electrochemical properties of the composites were systematically investigated. The results demonstrate that GDC nanoparticles were successfully coated onto the LSBCFM surface without disrupting the original morphology of the matrix, and the two phases exhibited excellent chemical compatibility at high temperatures. The introduction of an optimal amount of GDC effectively expanded the triple phase boundaries and constructed rapid transport channels for oxygen ions, thereby significantly enhancing surface oxygen exchange and catalytic capacity. The sample coated with 10 wt.% GDC exhibited optimal electrochemical performance, achieving a polarization resistance as low as 0.024Ω·cm² at 800 ℃. During full-cell testing in SOEC mode (50%H₂O-50% H₂), this electrode reached a current density of 1.223 A cm^-2 at 750 ℃ under an applied voltage of 1.3 V, corresponding to a peak theoretical hydrogen production rate of 8.52 ml cm^-2min^-1. In summary, surface modification of the LSBCFM material through an appropriate coating of GDC, which possesses high oxygen ion conductivity, can significantly enhance the catalytic activity and steam electrolysis performance at the oxygen electrode interface. This work provides an effective approach for the design and modification of high-performance composite oxygen electrodes for SOECs.