Lithium Polysulfide Radical Anions in Ether-Based Solvents

Abstract

Lithium sulfur batteries have a theoretical specific energy 5 times greater than current lithium ion battery standards, but suffer from the issue of lithium polysulfide dissolution. The reaction mechanisms that underlie the formation of lithium polysulfide reaction intermediates have been studied for over four decades, yet still elude researchers. Polysulfide radical anions formed during the redox processes have become a focal point of fundamental Li–S battery research. The formation of radical species has even been shown to be advantageous to the electrochemical pathways. However, whether polysulfide radical anions can form and be stabilized in common Li–S battery electrolytes that are ether-based is a point of contention in Li–S battery research. The goal of this work was to examine the presence of radical polysulfide species in ether-based solvents. Lithium polysulfide solutions in tetraethylene glycol dimethyl ether and poly(ethylene oxide) are probed using a combination of ultraviolet–visible (UV–vis...