Enhanced Ion Solvation and Conductivity in Lithium-Ion Electrolytes via Tailored EMC-TMS Solvent Mixtures: A Molecular Dynamics Study

Abstract

The development of stable, high-performance electrolytes is essential to addressing the safety concerns and limited lifespan caused by the thermal and chemical instability of traditional organic carbonate-based electrolytes in lithium-ion batteries (LIBs). This study examined the potential of mixed solvent systems, specifically ethyl methyl carbonate (EMC) and tetramethylene sulfone (TMS), to modify ion solvation and improve ionic conductivity in LIB electrolytes. Through molecular dynamics simulations, we investigated the solvation structure and transport properties of lithium ions (Li+) in these solvent environments. The inclusion of TMS altered the solvation structure, with TMS molecules preferentially coordinating with Li+ ions, displacing PF6- anions and reducing their electrostatic interference. Our results demonstrated a synergistic interaction between EMC and TMS, where an EMC/TMS ratio of 1:2 led to a significant improvement in ionic conductivity, reaching 0.91 mS/cm, with a corresponding Li+ transference number of 0.40. These findings provide key insights into the molecular-level interaction governing electrolyte behavior, offering guidance for the design of future solvent mixtures to improve the safety and efficiency of LIBs.