Enhanced Ionic\nConductivity via Suppressed Crystallization\nand Strengthened Dynamics in Solid Polymer-Blend Electrolytes: A Comprehensive\nBroadband Dielectric Spectroscopy Study

In this study, we\nintroduce solid polymer-blend electrolytes (SPBEs)\nin which the crystallization of poly(ethylene glycol) (PEG) is completely\nsuppressed. This achievement was realized by utilizing low molecular\nweight PEG and incorporating high molecular weight poly(vinylidene\nfluoride) (PVDF) as the blend matrix, resulting in flexible and self-standing\nSPBEs. Complete inhibition of PEG crystallization is observed when\nemploying the lower molecular weight of PEG or the higher concentration\nof lithium salt, leading to an impressive ionic conductivity of 2.9\n× 10<sup>–4</sup> S/cm at room temperature. Temperature-dependent\nionic conductivity shows a strong correlation between ionic transport\nand segmental motion of the blend matrix, following the Vogel–Tammann–Fulcher\n(VTF) relation. Further analysis of AC conductivity, electric modulus,\nand dielectric loss isotherms, obtained through broadband dielectric\nspectroscopy, reveals a coupling behavior between the relaxation times\nand the ionic conductivity. This experimental system can serve as\na model system for designing high-performance polymer-blend-based\nsolid electrolytes to achieve good mechanical properties and superior\nionic conductivities.