Single radiation-induced grafting method for the preparation of two proton- and lithium ion- conducting membranes

Abstract

Two distinct types of polymer electrolyte membranes for conducting protons and lithium ions have been prepared by a radiation-induced grafting method. The polymer electrolyte precursor (PVDF-g-PS) is obtained by the simultaneous grafting of styrene onto poly(vinylidene fluoride) (PVDF) followed by one of the two specific treatments. This includes sulfonation with a chlorosulfonic acid/dichloromethane mixture to obtain proton (H+)-conducting membranes, or activation with LiPF6/EC/DC liquid electrolyte to obtain lithium ion (Li+)-conducting membranes. The chemical structure of the obtained electrolyte membranes is verified by FT-IR spectroscopy. Differential scanning calorimetry is used to examine the changes in the crystallinity and the thermal properties of both lectrolyte membranes during the preparation process. The thermal stability of both electrolyte membranes is also evaluated using thermal gravimetrical analysis. The obtained polymer electrolyte membranes achieve superior conductivity values: 1.61 x 10-3 S.cm-1 for Li_ and 5.95 x 10-2 S.cm-1 for H+ at room temperature at a polystyrene content of 50%. The result of this work suggest that high quality H+- and Li+- conducting membranes can be obtained using a single radiation-induced grafting method.