Degradation mechanisms, long-term durability challenges, and mitigation methods for proton exchange membranes and membrane electrode assemblies with Pt/C electrocatalysts in low-temperature and high-temperature fuel cells: A comprehensive review

Abstract

Complying with durability regulations is crucial for the successful commercialization of proton exchange membrane fuel cells (PEMFCs). This study evaluates the literature on complex and multi-faceted degradation processes, durability, lifetime concerns, recent advancements, and mitigation measures for proton exchange membranes (PEMs) and membrane electrode assemblies (MEAs). Extensive research has explored the degradation mechanisms of low-temperature perfluorinated ionomers, such as Nafion®, alongside non-fluorinated PEMs, including hydrocarbon-based polymers and organic–inorganic nanocomposites. Additionally, high-temperature PEMs based on phosphoric acid-doped polybenzimidazole (PA-PBI) have also been reported. In MEAs, the Pt/C electrocatalyst, catalyst layer (CL), and gas diffusion layer (GDL) play crucial roles, with degradation occurring through Pt nanoparticles dissolution, electrochemical Ostwald ripening, Pt particles growth/precipitation on the membrane, carbon support corrosion, mass transfer difficulties for ionomer redistribution and reduced porosity, and membrane deterioration. For long-term durability in fuel cell operation, various influential factors are investigated such as accelerated stress tests (ASTs) for open-circuit voltage, dynamic load, humidity cycling, high temperature, freeze–thaw effects, Pt degradation, GDL, startup-shutdown state, different fuels, along with measurements of membrane properties and cell performance. Accelerated stress test protocols for transportation accurately depict long-term failure modes, targeting specific degradation paths or combinations of mechanisms. Mitigation strategies for these issues are also suggested. In addition, this study aims to contribute to advancing durability enhancement and mitigation strategies through a comprehensive analysis of novel material systems optimized for the development of next-generation low-temperature and high-temperature PEMs.