Novel Composite Membranes Based on Polyaniline/Ionic Liquids for PEM Fuel Cells Applications

The modern development of (PEMFCs) is still faced by several obstacles such as membrane cost and performance. Perfluorosulfonic acid membranes (e.g. Nafion of DuPont) are currently the most successful in PEMFCs. PEMFCs usually operate at temperatures around 80°C and at atmospheric pressure. Higher temperature operation (T >100°C) is preferred and has several advantages including enhanced fuel cell kinetics, improved catalysts tolerance for contaminants and recovery of useful heat. However, the high-temperature operation is not permitted using Nafion membranes as they dehydrate and their proton conductivity dramatically decreases, thus, lowering the fuel cell efficiency. Therefore, this work aims at developing a Nafion-free membrane that would successfully operate at higher temperatures and with reasonable proton conductivity (preferably higher than 10-3 S/cm). In this study, novel solid proton conductors based on polyaniline (PANI) and ionic liquids (ILs) are proposed as membranes in PEMFCs. PANI-IL composite membranes are fabricated using porous polytetrafluoroethylene (PTFE) as support. The composite membrane was evaluated for its proton conductivity. The results showed a high proton conductivity range of 0.01 to 0.02 S/cm when a 3.7 wt % of the ionic liquid (IL)[1-Hexyl-3-Methylimidazolium Tricyanomethanide] was used.