Manufacturing-to-Validation Workflows for Repeatable PEM Fuel Cells: A Review and Technology Perspective

Proton exchange membrane fuel cells (PEMFCs) are mature candidates for transportation and distributed power, yet product-level repeatability and durability are often limited by manufacturing and workflow variability rather than chemistry alone. Small deviations in coating uniformity, porous structure, interfacial contact, compression, hydration history, and test conditioning can accumulate across the membrane electrode assembly (MEA), leading to performance scatter. This review takes a practical, workflow-centric view that links fabrication choices to typical defects, failure modes, and measurable diagnostic signatures. Manufacturing-relevant elements are covered, including gas diffusion layer (GDL), catalyst layers and catalyst-coated membranes (CL/CCM) and flow fields and bipolar plates. Quality control and characterisation practices are summarised with emphasis on compression-dependent properties, wettability, and screening metrics. Assembly, activation/break-in approaches, and the evolution of testing toward harmonised protocols are also discussed. Overall, this review integrates manufacturing control, and technology perspective to define practical pathways for improving PEMFC repeatability, scalability, and product-level reliability.