Glycerol carbonate containing borate ester polymer electrolye syntheses

New borate ester based solid polymer electrolyte (SPE) membranes were successfully prepared via synthesis of boric acid with an ethylene glycol based diol (polyethylene glycol - PEG1000) and a cyclic carbonate group containing alcohol (glycerol carbonate – GC) in the presence of a lithium salt. During the preparation of these membranes, a slight stoichiometric excess of diol guaranteed the crosslinking of the polymer. The membranes with different lithium salts (LiClO4, CF3SO3Li ve (CF3SO2)2NLi) with varying ratios (ethylene oxide (EO):lithium cation(Li) ratio of 32, 24, 16 and 8) were prepared and compared in terms of their electrochemical and chemical properties. The prepared SPEs showed rather low Tg values (all below -30 °C) and no crystallinity especially at higher lithium salt ratios. The TGA thermogram results indicated that these borate ester based membranes were stable at least 300 °C with LiClO4 and 350 °C with the other salts. The temperature dependent ionic conductivity measurements revealed ionic conductivity values of 2.31 x 10-5 S/cm with LiClO4, 2.16 x 10-5 S/cm with CF3SO3Li and 4.09 x 10-5 S/cm with (CF3SO2)2NLi salts.