Develop High-Temperature, Low-Humidity Aromatic Hydrocarbon-based H2/O2 Membranes for Proton Exchange Membrane (PEM) Fuel Cells

Development of efficient fuel cells technology, especially based on H2/O2 fuel cells as an alternative energy/power source, has assumed a sense of global significance. From the viewpoint of minimizing water management issues and to provide for fuel cells with a simplified design, high durability and reduced costs, there is an ever-growing demand for a new generation of proton exchange membranes (PEMs) that can operate successfully at temperatures > 120ºC and at low relative humidity (< 25 %), ideally requiring no external humidification. During Phase I, this proposal aims at generating a novel class of PEMs, especially based on sulfonated polybenzimidazoles (SPBIs), with flexible linkages in the backbone. The premise is that, in contrast to the PEMs based on a relatively rigid heterocyclic polymer backbone, the flexible thermoplastic benzimidazole polymer backbone can facilitate the sequestration of the proton conducting domains more effectively, potentially increasing the proton conductivity to 50-100 mS/cm at high temperatures and at low relative humidity. Nanostructuring via the formation of PEM composites, incorporating ionic liquids and organically modified nanoclays in SPBIs, will also be explored in Phase I, from the viewpoint of enhanced hydrophilicity and proton conductivity of the PEMs.