(35d) Understanding the Gas Diffusion Layer in PEM Fuel Cells - Experimental Characterization, Design, and Manufacturability

The proton exchange membrane fuel cell (PEMFC) has a significant potential in transportation, backup, and portable power applications, although there still are some remaining technical and cost challenges. A key current challenge is improving the performance while reducing the cost of the gas diffusion layer (GDL). Designing a commercial GDL, however, is far more complex than simply making a porous, sturdy, conductive layer, because of the trade-offs among performance, manufacturability, and cost. An improved understanding of its multifarious functions in the fuel cell can help attain this goal. It is, thus, important to understand how each GDL parameter affects four interrelated key outcomes: 1) performance, 2) durability, 3) manufacturability, and 4) cost. Here, we examine 11 key properties of the GDL, how they influence these outcomes, how these are measured experimentally ex-situ, and how they can be altered via the manufacturing process. In particular, we investigate the correlation between measured ex-situ measured effective diffusivity and in-situ performance in a PEM fuel cell, as well as the impact of the MPL structure on cell performance under both wet and dry conditions.