Durability and Performance Analysis of Polymer Electrolyte Membranes for Hydrogen Fuel Cells by a Coupled Chemo-mechanical Constitutive Model and Experimental Validation

In this paper, a chemo-mechanically coupled behaviorof Nafion212 is investigated through predictive multiphysics modeling and experimentalvalidation. Fuel cell performance and durability are critically determinedby the mechanical and chemical degradation of a perfluorosulfonicacid (PFSA) membrane. However, how the degree of chemical decompositionaffects the material constitutive behavior has not been clearly defined.To estimate the degradation level quantitatively, fluoride releaseis measured. The PFSA membrane in tensile testing shows nonlinearbehavior, which is modeled by J (2) plasticity-basedmaterial modeling. The material parameters, which contain hardeningparameters and Young's modulus, are characterized in termsof fluoride release levels by inverse analysis. In the sequel, membranemodeling is performed to investigate the life prediction due to humiditycycling. A continuum-based pinhole growth model is adopted in responseto mechanical stress. As a result, validation is conducted in comparisonwith the accelerated stress test (AST) by correlating the size ofthe pinhole with the gas crossover generated in the membrane. Thiswork provides a dataset of degraded membranes for performance andsuggests the quantitative understanding and prediction of fuel celldurability with computational simulation.