The Effect of the Presence of ILs on the Strength and Ionic Conductivity of Nafion Membrane

Abstract

Proton exchange membrane, a key element of the proton exchange membrane fuel cell, with perfluorosulfonic acid (PFSA) membranes notably Nafion has been principally used as it provides high proton conductivity and high mechanical strength with good durability even at high pressure. Nonetheless, at high temperatures, the membrane suffers from conductivity problems due to dehydration, notably at high temperatures. Ionic liquids (ILs) which possess unique properties such as high electrochemical windows, high ionic conductivity, and high thermal stability have been the subject of interest in solving this problem. In this study, a protic ionic liquid 1-butyl-3-methylimidazolium trifluoromethanesulfonate (BMIMOTf) have been incorporated into the Nafion 117 through the solution casting and immersion method at different weight loading from 5–50 wt.% and tested their ionic conductivity, mechanical strength at different temperatures. It is found that at 20 wt.% loading the resulting composite membrane showed a high conductivity with considerable tensile strength. Furthermore, at different wt.% the incorporated ILs have improved the thermal stability of the membrane.