Proton-conductive aromatic membranes reinforced with poly(vinylidene fluoride) nanofibers for high-performance durable fuel cells

Durability and ion conductivity are counteracting properties of proton-conductive membranes that are challenging to achieve simultaneously and determine the lifetime and performance of proton exchange membrane fuel cells. Here, we developed aromatic ionomers reinforced with nonwoven poly(vinylidene fluoride) (PVDF) nanofibers. Because of the right combination of an isotropic nonwoven PVDF with high porosity (78%) and partially fluorinated aromatic ionomers (SPP-TFP-4.0), the resulting composite membrane (SPP-TFP-4.0-PVDF) outperformed state-of-the-art chemically stabilized and physically reinforced perfluorinated Nafion XL membrane, in terms of fuel cell operation and in situ chemical stability at a high temperature (120°C) and low relative humidity (30%). The SPP-TFP-4.0-PVDF membrane exhibited excellent chemical stability and stable rupture energy at high and low RH levels, allowing it to be an alternative proton-conductive membrane to meet the U.S. Department of Energy target to be used in automobile fuel cells in 2025.