Overcoming chromium poisoning in solid oxide cells through multiscale perovskite engineering

Chromium poisoning and sluggish oxygen kinetics limit oxygen electrodes in reversible solid oxide cells. We introduce a triple barrier design that integrates lattice stabilization by Ba to suppress SrO segregation, BaCoO₃ nanodomains that trap chromium, and surface acidity tuning via trace Mo at the B site in La_0.6Sr_0.1Ba_0.35Co_0.2Fe_0.78Mo_0.02O₃₋_δ. The electrode reaches 0.058 Ω·cm² polarization resistance at 750 °C, 70.4 percent lower than LSCF, delivers 1.352 W·cm⁻² at 800 °C, and 2.08 A·cm⁻² at 1.5 V. Under 0.5 A·cm⁻² with a chromium source, single cells operate stably for about 1000 hours. Quantitative characterization and thermodynamic analysis show suppressed SrCrO₄ formation and shallow chromium ingress, consistent with BaCoO₃ mediated trapping and Mo moderated surface basicity. Density functional theory at operating temperature and pressure indicates Ba and Mo together weaken CrO₃ adsorption. The design reconciles high activity with chromium tolerance and is transferable to related oxygen electrodes.