Impact of through-plane gas diffusion layer holes on fuel cell membrane durability deciphered by four-dimensional in-situ X-ray computed tomography visualization

The durability of modern reinforced membranes in proton exchange membrane fuel cell applications is generally considered proven. However, the potential influences of irregular features in adjacent components are commonly overlooked. In this work, the specific impacts of gas diffusion layer (GDL) holes on the combined chemo-mechanical membrane degradation mechanism and associated membrane durability are investigated, using four dimensional in situ X-ray computed tomography visualization. Purposefully designed small-scale membrane electrode assemblies (MEAs) are fabricated with through-thickness circular GDL holes of selected dimensions and locations on both anode and cathode. All hole locations show more rapid localized degradation than that at pristine regions. Among the three selected hole sizes (2.0, 0.5, and 0.2 mm 2 ), through-plane membrane cracks are only observed under the smallest holes, both at the hole center and edge. These MEAs with through-plane membrane cracks also had higher membrane thinning rate than the other MEAs; therefore, the through-plane membrane cracks likely elevated chemical stressors as well, presumably through increased gas crossover. Overall, the results suggest that GDL holes can be harmful to membrane chemo-mechanical degradation and the level of severity depends on their size and location. • The impact of GDL holes on mechanically reinforced membrane durability is evaluated. • 4D in-situ visualization reveals local membrane failure under some GDL holes. • Small GDL holes cause faster membrane degradation than larger ones. • Membrane cracks form at both the center and edges of GDL holes. • Membrane cracks increase gas crossover, facilitating membrane thinning.