Ion transport in polyacrylonitrile-based electrolytes with high LiTFSI contents

The evolution of the microstructures in polymer electrolytes composed of pr opylene carbonate (PC), polyacrylonitrile (PAN), and lithium bis(trifluorom ethane sulfone imide) (LiTFSI) has been characterized by Raman spectroscopy and the conduction behaviors of the electrolytes have been evaluated by ac impedance spectroscopy. The conductivity of the electrolyte depends strong ly on the association of the lithium ions and ion clusters with the electro n donor of the polymer. A transition from "salt-in-polymer" to "polymer-in- salt" electrolyte has been observed when the salt content is very high (PC: PAN:LiTFSI = 1:1:5). Based on these facts, the distinct roles of the polyme r are proposed on the transportation of the ionic species in conventional " salt-in-polymer" electrolyte and in "polymer-in-salt" electrolytes. (C) 200 1 The Electrochemical Society.