A new method for improving the conductivity of alkaline membrane by incorporating TiO2- ionic liquid composite particles

In this paper, we prepared a series of ionic liquids including methyl ionic liquids, ethyl ionic liquids and hydroxyethyl ionic liquids. We used the common polymer backbone polyphenylene ether and the conventional conductive group triethylamine. We introduced three different ionic liquids to investigate different effects of the extent of ion conductivity improvement from its structure change. The introduction of ionic liquid significantly improved the ionic conductivity of the alkaline membrane. The highest conductivity of the composite membranes was 2.5 times higher than that of the pure membrane. A certain amount of nano-TiO2 was added into the membranes through ultrasound dispersion to form a series of trimethylamine-nano-TiO2-ionic liquid composite membranes. We found that TiO2-ethyl ionic liquid composite membrane has optimal performance, whose ionic conductivity up to 59.27 mS/cm. and the degradation rate of ionic conductivity is 27.4% under strong alkali conditions. The water uptake and swelling ratio of the composite membrane are relatively low, and the thermal stability and mechanical properties also meet the requirements of the application. (C) 2017 Published by Elsevier Ltd.