Amorphous Room Temperature Polymer Solid Electrolytes

Abstract

Polymer electrolytes are ionic conductors of considerable technical interest due to the wide range of their possible applications in various devices. These materials exhibit many interesting properties, such as compatibility with alkali metal electrodes, a wide stability window, and easy method of preparation in a thin film configuration; however, relatively low ambient temperature ionic conductivity is their big disadvantage. From the considerations of Berthier et al. (1), it is evident that conductivity in polymer electrolytes is connected with the amorphous phase of the studied samples. Following this assumption, many methods leading to production of polymer electrolytes, in an amorphous form stable at room temperature, were developed. In our laboratory new concepts of producing highly amorphous polymer foils, such as preparation of polymer blends or grafted copolymers, utilization of PEO (poly(ethylene oxide)) copolymers of high molecular weight, and synthesizing of PEO-based polymer solid electrolytes with ceramic additives were introduced. All these methods enabled us to prepare PEO-based solid ionic conductors whose conductivity was 5×10⁻⁵ S/cm at room temperature and was two orders of magnitude higher than that obtained in the standard procedure.