Polymer Electrolytes Based on Polybenzimidazole, Poly(Vinylidene Fluoride-co-Hexafluoropropylene), and Ionic Liquids

Ionic liquids, salts with melting temperature below 100°C, have continuously attracted research interest. Introduction of ionic liquids in a polymer matrix affords polymer electrolytes exhibiting extremely high electroconductivity and electrochemical stability, membranes on their basis possessing good mechanical properties. Diversity of the polymers/copolymers suitable as the matrix as well as practically unlimited variety of ionic liquids (obtained via variation of the anion-cation composition and additional modification of the ions chemical structure) have afforded the polymer electrolytes with a wide range of the physico-chemical properties. In this study, the attention has been primarily focused on the results published over the recent decades and related to investigation of electrolytes for electrochemical devices, in which the membranes based on polybenzimidazole (meta-PBI), the poly(vinylidene fluoride-со-hexafluoropropylene) (PVdF-HFP) copolymer, and ammonium or imidazolium ionic liquids have been used. Various types of polymer electrolytes differing in the composition and the application range have been considered in this study: polymer + ionic liquid, polymer + ionic liquid + acid, and polymer + ionic liquid + lithium/sodium salt. Moreover, the influence of the fillers, introduced in the above-said polymer electrolytes to improve the properties and resolve the issue of the ionic liquid retention in the membrane, has been discussed. This report presents vast data sets (tables) on the electroconductivity and thermal stability of more than 100 polymer electrolytes, which are demanded by the broad journal audience.