Catalyst Ink Solvent Composition and its Impact on Polarization of Proton Exchange Membrane Fuel Cells Under Hydrogen/Air Operation

Systematized investigations of the manufacturing process of porous catalytic layers are crucial for the maturation of the hydrogen proton exchange membrane fuel cells (H2-PEMFC) technology. The present study reports the influence of the catalyst ink solvent, with 19 different compositions being investigated towards impact on characteristics (porosity) and on properties (H+ and O2 reactants mass transport resistances) of cathode catalyst layer (CCL), in dispersion of the Nafion ionomer and in H2-PEMFC polarization at high current loads. The Spearman's rank order provides an assessment of the correlations between all these measured quantities. While the concept of Hansen solubility parameter rationalizes the influence of the alcohol's nature and content in the solvent mixture on the dispersion of the Nafion, no correlation is found between the hydrodynamic diameter of Nafion aggregates and cell polarization at high current loads. However, an intrinsic relationship is revealed between the O2 and H+ mass transport resistances, suggesting that a trade-off exists to optimize the performances of the H2-PEMFC at high current loads. Finally, changes in the dielectric constant of the solvent forecasts the changes in characteristics and properties of the CCL, and the H2-PEMFC performances at high current loads with CCL prepared by ultrasonic spraying technique.