Benchmarking Ionic Conductivity of the Ternary Solvent-Salt-Polymer Composition Space in Liquid, Gel, and Polymer Electrolytes

Abstract

The development of liquid, gel, and polymer electrolytes is important for advancing batteries, supercapacitors, and fuel cells as they offer a wide and continuous composition space for electrolyte design. In the literature, polymer-containing electrolytes are liberally termed gel, plasticized polymer, quasi-solid, or semi-solid electrolytes based on their physical appearance, mechanical properties, or composition. In order to benchmark the ionic conductivity of these electrolytes, a unified analysis of the ternary solvent-salt-polymer composition space is made here, spanning approximately 0 to 96 wt % solvent content, 2 to 54 wt % lithium salt content, and 0 to 86 wt % polymer content, in which the solvent and lithium salt content largely determine the overall properties of the electrolyte. The results reveal a distinct transition from polymer-controlled to solvent-mediated conduction mechanisms at approximately 50 wt % solvent content, which is largely independent of salt concentration. Our analysis demonstrates how solvent content governs ion transport, which can be used to classify the electrolyte type and assess the performance of polymer-containing electrolytes.