Gas Diffusion Layers with Patterned Wettability

During PEFC’s operation the reactant gas is fed to the cell through the gas diffusion layer (GDL) and through the same material the product water is removed. Water accumulation near the catalyst can block the gas access causing an increase of the mass transport losses. On the other hand, PEFC’s work with a solid electrolyte membrane that needs to be hydrated in order to be proton conductive. In order to obtain the maximum performance PEFC’s required a well-balanced water management.

Gas and water are transported in counter flow through the GDL forming stochastically distributed pathways. To improve water transport, which is mostly driven by capillary forces, the most common strategy is to hydrophobize the GDL using a fluoropolymer, coating. This technique helps reducing water accumulation in the GDL. To further improve water management our group has developed a technology (patent pending) to create local hydrophilic and hydrophobic domains in GDL’s. By chemically modifying the coating on selected areas a hydrophilic region is created, the water is preferentially transported through these regions leaving a free path for the gas transport.

The addition of the pattern wettability improves the performance of the cell, particularly at high current densities. Using operando neutron imaging it can be seen that the water accumulates preferentially on the hydrophilic regions proving the effectiveness of the pattern.

• Full flexibility in the pattern design
• No mechanical damage on the GDL
• Economically feasible, compatible with roll-to-roll manufacturing processes