Modeling Mechanical Behavior of Membranes in Proton Exchange Membrane Water Electrolyzers

Membranes in proton exchange membrane water electrolysis (PEMWE) stacks are exposed to severe mechanical stress due to mechanical compression. Particularly critical is the gap between cell frame and porous transport layers (PTL). In this work mechanical stresses and strains on the membrane occurring during assembly and operation are quantified using a finite-element analysis applied to a simplified single cell sandwich. Within the simulation a Nafion ® 117 membrane and the elastic-viscoplastic Silberstein material model is used. The material model parameters are based on and validated by experimental data from tensile tests to ensure matching with real PEMWE systems. The validated material model is used in cell simulations to identify resulting stresses and strains acting on the membrane. In accordance with experimental data, no critical states were identified. Furthermore, differential pressure up to 10 bar could not cause any significant change compared to deformations resulting during balanced pressure operation. Varying the gap size between cell frame and PTL resulted in a buckling in the simulated membrane for sizes of 0.3 mm and more during the membrane swelling. Such simulations can improve future cell designs while using an appropriate gap size with a given membrane thickness to avoid buckling and therefore possible failures.