Experimental study of gas diffusion layers nonlinear orthotropic behavior

Abstract

One of the most important components of PEMFC is the gas diffusion layer (GDL), owing to its key role in the reactant diffusion, water management, thermal and electron conductivity. Therefore, the GDL must have an optimal stiffness to ensure these transport functions during numerous hydrothermal cycles. The understanding of its behavior is still a remaining issue. Its orthotropic mechanical behavior requires a series of mechanical characterizations in the plane of the fibers and out of plane. In addition, there are different manufacturing processes for GDL in sheet or roll form to optimize its functional properties. A macro porous layer (MPL) or different PTFE contents might be added by different manufacturers to optimize its performance. In this study, we have performed several mechanical tests differentiating between in plane and out of plane properties in order to characterize different GDLs available on the market. All of the experimental work has been done in the machine (MD) and cross machine direction (CD) according to the fiber orientation. The different GDL types were then classified into categories presenting similar mechanical response.