(490b) Advanced Water Management in Polymer Electrolyte Fuel Cells Using Engineered Gas Diffusion Layers with Patterned Wettability

The water management in polymer electrolyte fuel cells (PEFCs) is a rather complex issue [1]. On one hand side, some water is needed to hydrate a proton conductive membrane and ionomer in the catalyst layers. Therefore, humidified gases are fed into the cell. On the other hand, excessive amounts of water in the porous layers lead to blockage of available pores for gas transport and consequently increased mass transfer limitations, especially at high current densities when large amounts of water are produced. The gas diffusion layers (GDLs) are highly porous carbon fiber materials which are sandwiched between electrodes and flow fields and provide several functionalities: conduction of electricity and heat, mechanical integrity of the membrane, distribution of reactant gases and removal of the liquid water produced. These functions imply a triple set of contradictory requirements: high diffusivity of the gas phase, high permeability of the water phase, and high thermal and electrical conductivity of the solid phase [2].

The creation of artificial pathways for water removal within the porous material can enable the development of advanced water management strategies; however none of the existing approaches proposed a method to produce such materials in a way compatible with mass productions. To tackle this issue, we invented a method to produce GDLs with patterned wettability based on localized electron radiation grafting [2]. The method permits creating dedicated through-volume hydrophilic patterns for selectively removing water, while the remaining material maintains its hydrophobic character. In this talk, the details of the synthetic method will be discussed first [3]. Later, electrochemical characterization of operando cells combined with neutron radiography will be discussed to demonstrate the potential of these materials to improve power density at various conditions due a reduced mass transfer overpotential [4].

References

[1] T. V. Nguyen et al., 1993 J. Electrochem. Soc. 140(8), 2178-2186.

[2] A. Forner-Cuenca et al., Adv. Mater. 2015, 27, 6317-6322.

[3] A. Forner-Cuenca et al., J. Electrochem. Soc. 2016, 163 (8), F788-F801.

[4] A. Forner-Cuenca et al., J. Electrochem. Soc. 2016, 163 (13), F1389-F1398.