Ionic Conductivity and Electrochemical Stability of Poly[oligo(ethylene glycol)oxalate]−Lithium Salt Complexes

A new series of highly conducting polymer electrolytes based on poly[oligo(ethylene glycol)oxalate], P(EGnO) where n represents the number of repeating ethyleneoxy unit, has been prepared. The dielectric constant of the polymer host is higher than that of the pure poly(ethylene oxide) due to the existence of the two carbonyl groups in the repeating unit. A maximum conductivity of 5.9 × 10-5 S cm-1 at 25 °C was obtained for the complex of LiTFSI and P(EG23O) with a molar salt concentration of [Li+]/[EO] = 1:16. The complexes also show good electrochemical stability up to 4.4 V versus Li+/Li.