Thermal and structural characterizations of PEO–EMIHSO4 polymer electrolytes

Solid polymer electrolytes containing poly(ethylene oxide) (PEO) and 1‐ethyl‐3‐methylimidazolium hydrogensulfate (EMIHSO4), an ionic liquid, were investigated. Thermal and structural properties of this polymer electrolyte were characterized using DSC, XRD, and FTIR. After addition of EMIHSO4, the melting point of PEO decreased by ca. 25 °C. Thermal and structural analyses indicated that the crystallinity of PEO substantially decreased with increasing EMIHSO4 content. The interaction between ionic liquid and polymer suggested further dissociation of the ionic liquid. Thus, EMIHSO4 acted as ionic conductor and plasticizer.

► Polymer electrolytes based on EMIHSO4 ionic liquid were developed and characterized.
► The addition of EMIHSO4 greatly decreased the crystallinity of PEO.
► PEO further facilitated the ionic dissociation of EMIHSO4.
► EMIHSO4 acted as ionic conductor and plasticizer in the polymer electrolyte.