A plasticized poly(alkyleneoxy)acrylate-based polymer electrolyte with high ionic conductivity

Abstract

In this communication a highly conductive, plasticized polymer electrolyte, based on a UV-curable poly(alkyleneoxy)acrylate-LiCF,SO, complex, is described. This polymer electrolyte is a thermally stable transparent solid, and thus has the potential for use in solid state electrochromic devices. The plasticizer is added to the polymer electrolyte to increase the ionic conductivity, which is a concern with respect to the switching speeds of electrochromic devices [1,21. Methacrylate-based polymers containing ethyleneoxide units, either as sidechains or incorporated in crosslinks, have been explored previously as hosts for solid polymer electrolytes, with and without plasticisers [3-71. A monoacrylate-based polymer was chosen for this work because of the more flexible backbone of the polyacrylates. The use of plasticizers to increase the conductivity of solid polymer electrolytes to the order of 10m3 S cm-’ is well known [4,8-141. Plasticizers have also been used to increase the ionic conductivity of polyelectrolytes [ 151. Plasticizers with high dielectric constants, such as propylene carbonate or ethylene carbonate, increase both the number of charge carriers and ion mobility in the polymer electrolyte by solvating the complexed salt. Similar results are seen by adding cryptand ligands to Na+-conducting polyelectrolytes 1161. Another example of the effect of a strong propylene carbonate plasticizer-salt interaction is presented for the polymer electrolyte described here.