The effect of thickness on conductivity of Nafion-based blend membranes

• Laura Pham, Chemical Engineering, University of Delaware

• Pradip Das, Chemical & Biomolecular Engineering, University of Delaware

Proton exchange membrane fuel cells (PEMFCs) utilize hydrogen as a fuel source and convert chemical energy into electrical energy through electrochemical processes. Nafion, a perfluorosulfonic acid-based membrane developed by DuPont in 1962, remains the industry standard for proton exchange membranes (PEMs) due to its high proton conductivity and ion exchange capacity. However, Nafion presents several limitations, including a narrow operational temperature range (<100 °C) and reduced proton conductivity under anhydrous conditions. While ongoing research aims to address these limitations through material modifications, membrane thickness is another critical parameter that is often overlooked. Thickness significantly influences membrane resistance and mechanical stability—thinner membranes tend to offer higher proton conductivity but lower mechanical strength, whereas thicker membranes have improved durability at the cost of reduced conductivity. In this study, a 20 wt% Nafion solution was cast into membranes with varying thicknesses (40 to 100 µm) to evaluate baseline physicochemical properties. The Nafion ionomer was then blended with a series of macromolecular additives at different weight percentages to probe its overall membrane performance (water uptake, ion exchange capacity, and conductivity) in these modified materials. This work provides a foundation for the future development and optimization of Nafion-based blended membranes for proton exchange applications.