A Three-Descriptor Framework for Solvation Design of Low-Temperature Electrolytes in Lithium Batteries

Abstract

Low-temperature operation of lithium–metal batteries is limited by kinetic penalties in electrolytes, yet electrolyte discovery for subzero operation remains largely empirical, lacking a predictive basis linking molecular structure to Li+–solvent interactions. Here, we establish a three-descriptor topology–electronic coupling framework combining O–O bond separation, lone pair orbital contribution and net oxygen charge to predict Li+–solvent binding energetics by screening a diverse ether, ester, ketone, carbonate, and sulfone solvent library. 2,2,2-trifluoroethylmethanesulfonate (TM) featuring S═O moiety and −CF3 group is identified as a solvent model that favors weakly point-contact Li+ coordination, which effectively lowers the desolvation barrier, induces anion-involved solvation structures, and promotes the formation of an inorganic LiF-rich interphase. A newly formulated electrolyte consisting of lithium bis(fluorosulfonyl)imide (LiFSI), 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether (TTE), and TM delivers 99.38% Li plating/stripping Coulombic efficiency and enables reversible Li||Ni0.8Mn0.1Co0.1O2 cells at −60 °C with a cutoff voltage of 4.6 V. This multi-factor solvent-screening strategy advances electrolyte design from empirical trial-and-error toward descriptor-guided development.