Decoupling Electronic–Ionic Transport and Catalysis Enables High‐Performance, Chemically Stable Sr‐Free Air Electrodes for High‐Temperature Solid Oxide Cells

Although strontium is a major origin of various degradation mechanisms in high-temperature electrochemical cells, it is inevitably employed as an A-site dopant in perovskite air electrodes to ensure adequate functionality. Herein, we report a high-performance Sr-free air electrode achieved by independently tailoring electronic conduction, ionic transport, and surface catalytic activity. High electronic conductivity is realized using multi-valent B-site perovskites with fully La-occupied A-sites, while efficient ionic transport is provided by oxygen-interstitial Ruddlesden-Popper phases without Sr doping. Moreover, highly active nanocatalysts are incorporated via infiltration to accelerate surface reaction kinetics, enabling electrochemical performance comparable to that of state-of-the-art Sr-containing electrodes. Full cells employing this electrode exhibit exceptional durability under harsh electrolysis conditions, particularly under severe Cr vapor exposure. While conventional Sr-based electrodes exhibit rapid degradation of ∼15% within 100 h owing to reactions between segregated Sr and Cr vapor, the Sr-free electrode maintains stable performance with no detectable decay over 200 h of continuous operation. This design strategy offers a scalable and immediately applicable pathway to resolve critical durability issues in high-temperature electrochemical energy systems.