Recent advances and challenges in degradation issues of direct ammonia solid oxide fuel cells: comprehensive review

Direct ammonia solid oxide fuel cells (DA-SOFCs) are promising energy-conversion devices that serve as alternates to hydrogen (H₂)-fueled SOFCs, given their potential to overcome the current limitations of green hydrogen, e.g., the high costs of production and transportation as well as the low volumetric energy density and high storage levels. Unlike H₂-fueled SOFCs, DA-SOFCs can offer high efficiency and approachability based on the already well-established value chain of ammonia. However, despite these advantages, recent studies on DA-SOFCs have reported significant degradation issues in many aspects, all of which should be carefully considered for broader commercialization. In this review, we introduce the recent progress and challenges related to DA-SOFCs, focusing more on degradation issues and methods capable of suppressing them in three directions: (1) materials, (2) cells, and (3) systems. Therefore, the study provides motivation for additional research directions for the development of DA-SOFCs.