Numerical and experimental characterization of gas permeation through membranes with consideration of mechanical degradation in proton exchange membrane fuel cells

Exposed to severe loading condition in fuel cells, the perfluorinated sulfonic-acid (PFSA) membrane degrades over time, which becomes the primary cause of the increasing transmembrane gas permeation during the service. As a result, the hydrogen crossover rate increases with the damage propagation, leading to loss in power and life. However, the effect of mechanical degradation on gas permeability of membrane cannot be quantitatively estimated due to difficulties in damage observation and modeling. This paper first establishes a numerical technique to predict the gas permeation through membrane with consideration of mechanical degradation. Blister test as well as gas permeation test are conducted for the verification of the numerical model. The model shows great prediction accuracy, based on which the uneven distributed damage and its effect on gas permeability are analyzed. Result shows that the gas permeation rate grows with pressure and mechanical degradation has a remarkable contribution, accounting for about 7.3% of total permeation rate at testing pressure of 130 kPa. Finally, the varied membrane shape and gas permeability, which all accelerate the gas permeation, are further analyzed based on the numerical model.