Durability of sulfonated polyimide membrane in humidity cycling for fuel cell applications

An aromatic proton conductive polymer, sulfonated polyimide copolymer membrane, was tested in humidity cycling under the conditions simulating fuel cell operation. The membrane was exposed periodically (every 2 min) to dry (nominal 0% relative humidity) and wet (100% relative humidity) at 80 °C, similar to the United States Department of Energy (US DOE) protocol for proton exchange membrane fuel cells. The membrane was durable for 10,000 cycles without mechanical failure. Post-test analyses by 1H NMR spectra and gel permeation chromatography (GPC) revealed that the membrane was hydrolyzed to some extent during the cycling test while mechanical properties and gas impermeability were only slightly deteriorated.

► Durability of a sulfonated polyimide membrane has been tested in wet/dry cycling. ► The membrane was durable for 10,000 cycles without mechanical failure. ► Post-test analyses revealed that the membrane was hydrolyzed to some extent. ► Mechanical properties and gas impermeability were only slightly deteriorated.