Unveiling the Synergy of Polymer–Salt Compositions for Properties Enhancement of Solid Polymer Electrolytes Based on PEO/PVP Blend Polymer Matrix and LiTFSI Dopant Salt

Abstract

Solid polymer electrolytes (SPEs) are ion-dipole complexes credited for their use in the design and development of widespread solid-state ion-conducting innovative devices. Herein, two sets of highly flexible, stretchable, and sticky-type ternary SPE films based on poly(ethylene oxide) (PEO)/ poly(vinyl pyrrolidone) (PVP) blend as host matrix of different compositional ratios (i.e., 25/75, 50/50, and 75/25 wt/wt%) with 30 and 50 wt% lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) as ionic dopant salt, and also one sample of polymer-in-salt (PiS) comprised the 50/50 wt/wt% polymer blend matrix and 60 wt% salt, are prepared and characterized in detail. These SPEs are predominantly amorphous, having substantial absorbance for ultraviolet-visible radiations and tunable wide range energy band gaps. The 20 Hz to 1 GHz broadband dielectric permittivity, loss angle tangent, and electrical conductivity spectra explained a variety of polarization and structural relaxation processes and the mechanism of ion transport ruled by the compositional synergy of polymer and salt in these SPEs. The highest ionic conductivity with appreciable electrochemical performance of the SPE is found for the PEO-rich blend matrix with 50 wt% of LiTFSI dopant. We conclude the suitability of these SPEs for development of futuristic ion-conducting energy storage as well as revolutionary iontronic devices