Phosphoric acid doped hydrophobic ionic liquid-based composite membranes for anhydrous proton exchange membrane application

Abstract

In this study, phosphoric acid doped hydrophobic ionic liquid-based composite membranes are successfully synthesized and characterized. 1-Vinyl-3-butylimidazolium bis(trifluoromethylsulfonyl)-imide ([VBIm][NTf₂]) was synthesized and used as hydrophobic phase in the composite membranes. The H₃PO₄ uptake of the composite membranes increases with the increasing content of [VBIm][NTf₂] and then decreases. The resultant composite membranes showed good thermal stability, mechanical properties and high proton conductivity (up to the order of 10⁻² S cm⁻¹ at 180 °C) at high temperatures under anhydrous conditions. The results of this study suggest that this type of PEMs have good perspectives for high temperature proton exchange membrane fuel cell applications.