A Durable and Highly Active Oxygen Electrode for Solid Oxide Cells: New Insight into Segregation Suppression of Layered Perovskite

One challenge to realize the commercialization of solid oxide cell technology is the instability and poor catalytic activity of the oxygen electrode during stack operation caused by Cr-containing alloy interconnect. Particularly well-known Sr/Ba-containing perovskite oxides can easily segregate Sr/Ba to the surface, reacting with vaporized Cr and causing Cr poisoning. To address this challenge, this work designs an entropy-driven layered structural strategy to suppress the surface segregation of cations and realize substantial enhancement of catalysis activity and Cr tolerance. The investigations suggest that the planar strain generated by entropy increase in the rare earth layer plays a pivotal role in suppressing alkaline earth segregation. Consequently, the half-cells with (La_0.25Pr_0.25Nd_0.25Sm_0.25)Ba_0.5Sr_0.5Co_1.5Fe_0.5O_5+δ (LPNSBSCF) oxygen electrode exhibit significantly improved stability in various operation conditions with Cr containment. Furthermore, LPNSBSCF shows the high power density of 2.12 W cm⁻² at 800 °C and 1.41 W cm⁻² at 650 °C in the single cells of oxygen ion and proton type, respectively. This paper provides new insights into segregation suppression in layered perovskite and offers theoretical guidance for the rational design of oxygen electrodes to achieve high Cr-tolerance and catalytic activity.