Failure modes of polymer electrolyte membrane fuel cell membrane-electrode assemblies in air-independent applications

Air-independent polymer electrolyte membrane fuel cells (PEMFCs) operate with pure O 2 in closed systems, subjecting membrane-electrode assemblies (MEAs) to high O 2 activity, prolonged high-voltage idling, and humidity or pressure transients. Durable performance under these air-independent propulsion (AIP)-specific stressors is critical for sustainable, long-endurance power systems. However, systematic investigations of MEA failure mechanisms under AIP conditions remain limited. This study addresses the key question of which degradation pathways dominate under representative AIP operating profiles. Five protocols—open-circuit voltage holding, load and relative-humidity cycling, and constant-current operation in recirculation and dead-end modes—were evaluated, revealing radical attack and mechanical fatigue as the primary degradation factors for MEAs in AIP systems.