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

ABSTRACT

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.