Neutron tomography is used to visualize the effect of hydrophobicity variations within the micro porous layer (MPL) and membrane electrode assembly (MEA) of a low-temperature polymer electrolyte fuel cell (PEMFC) on the detailed distribution of water in an operating cell. MEAs and MPLs manufactured in-house with different degrees of wettability are implemented in miniature fuel cells featuring an active area of 8 cm², which are specifically designed for neutron imaging experiments. The tomographies are obtained with a pixel size of 13 µm while maintaining the same operating conditions for all cells for comparability.

The quantitative analysis of the water content in two of these cells next to the lands and the channels of the flow field is shown in Figure 1. It can be clearly observed that the implementation of a hydrophobic MEA significantly changes the overall water distribution within the cell. In contrast to the reference MEA, where more water is found in the catalyst layers compared to the membrane, the hydrophobic MEA has a higher water content inside its membrane.

Implementing a GDL with a more hydrophobic MPL on the cathode side shows a higher water content inside the GDL substrate under the lands compared to the channels. This information can significantly help the optimization of material designs and can also provide valuable data for modeling and simulations of water distributions inside PEMFCs. We will show a detailed analysis of hydrophobicity changes on the water distribution inside the cell components, characterization results of various MPLs and MEAs regarding wettability and porosity analysis as well as performance results at different operating conditions