Polymer solid electrolyte from amorphous poly[epichlorohydrin-co-(ethylene oxide)]/lithium perchlorate complex

Abstract

High molecular mass copolymers (P(EH/EO)s) were synthesized by coordination anionic polymerization of ethylene oxide (EO) and epichlorohydrin (EH), and P(EH/EO)s were used for the preparation of the ion-conducting matrix. The copolymers having EO unit contents of less than 63 mol% were amorphous, and subjected to the complexation with lithium perchlorate. The temperature dependence of ionic conductivity of the P(EH/EO)/LiClO4 complexes was expressed by the Williams–Landel–Ferry equation. Optimal conductivity was observed as a function of salt concentration. This is the result of two contradictory factors: the increase of glass transition temperature (negative for the ionic conductivity) and the increase of carrier number (positive for the ionic conductivity) with increasing lithium perchlorate concentration. The ionic conductivity strongly depended on EO unit contents in the copolymers. The introduction of EO units to poly(epichlorohydrin) main chain increased the ionic conductivity as did the addition of 20 wt% poly(oxyethylene) glycol monomethylether of molecular mass 750. © 2000 Society of Chemical Industry