Guided Water Percolation in 3D-Printed Gas Diffusion Layers for Polymer Electrolyte Fuel Cells.

The accumulation of liquid water in the gas diffusion layer (GDL) and associated clogging of the reactant pathways are limiting factors for the performance of polymer electrolyte fuel cells (PEFC). The design and manufacturing of GDLs with a deterministic pore space have the potential to accelerate the development of next-generation PEFC with an optimized balance between reactant supply and product removal. In this study, we explore the potential of GDLs with tailored pore structures obtained from the carbonization of a 3D-printed precursor. Three different GDL designs are investigated by using operando X-ray radiography and subsequent X-ray tomography to track the water pathways. The results confirm the effectiveness of the designed features in terms of controlled liquid water percolation and reveal a trend toward vapor phase transport rather than liquid transport of water away from the catalyst layer interface along with a strong convective flow within the highly porous ordered structures.