Hydration and Dimensional Control in Porous Polyvinylidene Fluoride-Supported Short-Side-Chain Perfluorosulfonic Acid Membranes for Low-Humidity Hydrogen Fuel Cells

This work presents the design of a composite polymer electrolyte membrane by integrating a short-side-chain (SSC) perfluorosulfonic acid (PFSA) film within thin porous layers of poly(vinylidene fluoride) (PVDF) to enhance water retention and dimensional stability, particularly under low-humidity fuel cell operating conditions. The porosity in the PVDF layers was achieved by optimizing the PVDF-to-urea ratio. This composite structure effectively reduces the moisture desorption rate from the SSC PFSA core as the hydrophobic PVDF layers mitigate water loss. Additionally, it helps control excessive swelling, improves dimensional stability, and limits hydrogen crossover through the membrane. Fuel cell performance and electrochemical impedance analysis confirm that the proposed membrane structure is a promising approach for efficient operation in low-humidity PEM fuel cell applications. At 30% RH, current density improved by 54% and 24% under H2–O2 and H2–air conditions, respectively.