Low-temperature gelled electrolytes based on the salt LiN(SO2CF3)2 in mixed glyme solutions for lithium power sources

Abstract

New low-temperature gelled electrolytes based on 1 M LiN(SO₂CF₃)₂ in mixed solutions of glymes and 1,3-dioxolane with the addition of 1 wt.% polyethylene oxide (PEO) were obtained. The conductometry method was used to demonstrate that all the compositions have a conductivity of 7–8 and 3–4 mS cm⁻¹ at 20 at −20 °C, respectively. The interface between the electrolyte and the metallic lithium was investigated using electrochemical impedance spectroscopy. The composition 1 M LiN(SO₂CF₃)₂ in a mixture of dioxolane—dimethoxyethane—diglyme—tetraglyme (1: 2: 2: 1 v/v) + 1 wt.% PEO was found to be the best for low temperatures. Quantum chemical modeling of solvate complexes of the Li⁺ cation was used to propose a mechanism for improving ion transport from glyme solvates along the PEO chain.