Effects of [Bmim]OH on structure and conductive properties of alkaline PVA/[Bmim]OH membranes

Abstract

A series of alkaline polyvinyl alcohol/1-ethyl-3-methylimidazolium hydroxide (PVA/[Bmim]OH) electrolyte membranes were developed via a direct blending and solution casting method. The structure and conductive properties of PVA/[Bmim]OH membranes with various concentrations of [Bmim]OH were systematically studied using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), attenuated total reflectance Fourier-transform infrared (ATR-FTIR), tensile-strength analysis, and AC impedance spectroscopy. When blended, the PVA/[Bmim]OH membrane exhibited superior ionic conductive and the maximum ionic conductivity was found around 0.0196 S cm−1 when the weight ratio of [Bmim]OH to PVA was 2.0. A model was proposed to illustrate the structure of PVA/[Bmim]OH membranes and the effect of [Bmim]OH on the ionic conductivity of the PVA matrix. The results and the model indicated that the addition of [Bmim]OH could significantly improve the electrochemical properties of the membranes, which is a promising candidate for direct methanol fuel cells (DMFCs) applications.