Hückel anion based concentrated electrolytes for lithium–sulfur batteries

Abstract

Hückel anion-based lithium salts present a promising alternative to conventional LiTFSI electrolytes for lithium–sulfur (Li–S) batteries by reducing lithium polysulfide (LiPS) solubility while maintaining favourable electrochemical properties. This study systematically investigates the performance of LiTDI, LiPDI, and LiHDI-based electrolytes in a DOL : DME (1 : 1) solvent system. Raman spectroscopy, ionic conductivity, and viscosity measurements reveal distinct ion association behaviours, with molecular dynamics simulations confirming preferential Li⁺ solvation by DME. Electrochemical cycling tests demonstrate stable discharge capacities, particularly at higher salt concentrations. Operando Raman spectroscopy provides direct insight into LiPS evolution, confirming that higher salt concentrations slow down LiPS dissolution and diffusion, mitigating the LiPS shuttle effect. Additionally, COSMO-RS modeling predicts significantly reduced Li₂S₈ solubility with increasing salt concentration. These findings highlight the potential of Hückel anion-based electrolytes in advancing high-performance Li–S battery technologies.