(2-oxo-1,3-dioxolan-4-yl)methyl side groups containing poly(ethylene glycole)-borate ester polymer electrolytes

New solid polymer electrolytes (SPE) were successfully prepared by reacting boric acid in the presence of a lithium salt with a diol in varying chain lengths (poly(ethylene glycol)-PEG(4000, 1000, 600, 400, 200) and an alcohol containing cyclic carbonate (glycerol carbonate–GC). Among the target borate ester based polymer electrolytes, it was found that the optimum polymer electrolyte system was prepared by PEG600. After that series of polymer electrolytes in the presence of different salts (CF3SO3Li, (CF3SO3)2NLi and LiPF6) and varying salt rations (ethylene oxide (EO):Lithium salt (Li) = 32, 24, 18, 12) were prepared with PEG600 and their chemical and electrochemical properties were compared. The highest room temperature ionic conductivity value was found to be 2.39x10-5 S/cm with polymer electrolyte containing (CF3SO2)2NLi) salt at EO:Li=24:1 salt ratio. Furthermore, the cyclic voltammograms of the polymer electrolytes containing different lithium salts at EO:Li=24:1 salt ratio showed that they were stable up to 5V against the Li+/Li reference electrode.