Microscopic Mechanisms of Hydrogen Permeation in <scp>PEMFC</scp> Sealing Materials: A Review of Molecular Simulation Studies

ABSTRACT Hydrogen permeation through sealing materials poses a significant challenge to the safety and durability of proton exchange membrane fuel cells (PEMFCs). This review systematically summarizes recent advances in employing molecular simulation techniques, specifically molecular dynamics (MD) and grand canonical Monte Carlo (GCMC), to elucidate the microscopic mechanisms of hydrogen transport in rubber seals. The application of the solution‐diffusion model is analyzed, highlighting the critical roles of free volume topology, polymer chain dynamics, and interfacial interactions in determining barrier performance. We compare the permeation characteristics of typical elastomers, including EPDM, NBR, FKM, and VMQ, and discuss the impact of environmental factors. Notably, the review emphasizes micro‐mechanisms often inaccessible to macroscopic experiments, such as the non‐Fickian sub‐diffusion caused by the crowding effect under high pressure and the trapping phenomena at filler interfaces. Finally, the potential of molecular simulations in guiding the design of next‐generation high‐barrier sealing materials is discussed, providing a theoretical basis for material optimization.