Pathways to Mitigate Chromium Poisoning in Electrolysis Devices

Solid oxide (SOFC/SOEC) and protonic ceramic (PCFC/PCEC) electrochemical cells are key enabling technologies for the future energy transition. These high- and intermediate-temperature devices offer exceptional efficiency and fuel flexibility, positioning them as critical components in decarbonizing sectors where low-temperature systems fall short. Chromium (Cr) poisoning remains one of the most critical degradation mechanisms limiting the performance, durability, and commercial viability of these solid oxide and protonic ceramic electrochemical cells (SOCs and PCCs). Cr volatilization from ferritic stainless steel interconnects and subsequent deposition of volatile Cr species such as CrO3 and CrO2(OH)2 at the oxygen electrode lead to the formation of electrically insulating phases, which compromise triple-phase boundary (TPB) activity, increase polarization resistance, and accelerate performance degradation. While Cr-related degradation has been extensively studied in SOCs, its impact on PCCs, which are promising candidates for efficient hydrogen production remains comparatively underexplored. This review critically analyzes Cr poisoning mechanisms across these electrochemical systems, highlighting the mechanistic differences arising from their distinct configurations, ion conduction modes, and operating environments. Advances in material innovations, including Cr-resistant alloys, protective coatings, and improved electrode formulations, are discussed with a focus on their cross-system applicability and effectiveness. The need for predictive modeling, long-term durability studies, and system-level validation under realistic conditions is emphasized as essential for advancing Cr mitigation strategies. By consolidating current understanding and identifying key research gaps, this review outlines strategic directions for the development of Cr-resilient materials, optimized getter integration, and tailored protection schemes for the unique challenges posed by PCECs. Ultimately, it underscores the urgency of developing robust, scalable solutions to enable the reliable deployment of next-generation high-temperature electrolysis technologies in sustainable energy systems.