Computational insights into Li+ coordination and redox stability of Sulfolane vs. ethylene carbonate electrolytes: A DFT study with literature benchmarking

Finding electrolyte systems with improved thermal and electrochemical stability is important as traditional organic carbonates such as Ethylene Carbonate (EC) have low flash points and are prone to oxidative decomposition at high-voltage cathodes. Herein, Tetramethylene Sulfone (Sulfolane, TMS) is investigated using density functional theory at ωB97X-D4/def2-TZVP level. TMS demonstrates advantageous coordination with Li + due to its high boiling point (287.3 °C) and flash point (165 °C). The binding energy of TMS is −53.39 kcal/mol, about 5.2% lower than EC (−56.82 kcal/mol), suggesting a lower desolvation penalty. The higher LUMO level of TMS (by 0.67 eV) indicates greater resistance to reductive decomposition than EC. The HOMO of TMS (−8.24 eV) is higher than EC (−8.65 eV) by 0.41 eV, while the calculated dipole moment (4.81 D) agrees with experiment (4.10 D). This purely computational study employs a 1:1 cluster model; multi-solvent clusters and experimental validation remain future work.