Mechanical characterization and analytical modeling of gas diffusion layers under cyclic compression

• Three industrial Gas Diffusion Layers are analyzed under cyclic mechanical pressures.
• The GDL mechanical response is strongly nonlinear versus pressure.
• A stabilized mechanical behavior is obtained after five loading/unloading cycles.
• An analytical model is developed with a good agreement versus the measurements.
• The mechanical behavior is modified by the PTFE coating and the MicroPorous Layer.

Gas Diffusion Layers (GDLs) play a major role in the performances of Proton Exchange Membrane Fuel Cells (PEMFC). However, their mechanical properties are poorly studied in the literature. In fact, most papers treating an overall PEMFC assume a linear GDL behavior. Articles focusing on GDLs sometimes consider a nonlinear behavior or cyclic compressions above 6 MPa, but no paper considers these two constraints at the same time. Yet it has been proven that a GDL in a running fuel cell undergoes local pressures higher than 10 MPa and has a nonlinear response. The purpose of the present study is to investigate the mechanical behavior of three industrial GDLs under those extreme coupled conditions. In this paper, the results of the experimental investigation are presented. Then, an analytical model is developed. A nonlinear behavior is obtained and compared to the experimental data. A good agreement between the experimental data and the analytical model is obtained for each GDL reference.