Dispersion‐Force‐Induced Dipole–Dipole Interaction and Its Effects on Solvation Chemistry of Lithium‐Ion Batteries

ABSTRACT Weakly‐solvated electrolytes (WSEs) with rapid Li ⁺ desolvation are crucial for the stable operation of lithium‐ion batteries at subzero temperatures. Due to the weak Li ⁺ ‐dipole interaction, van der Waals forces mediated by dipole–dipole (d–d) interactions could influence electrolyte solvation structure and desolvation kinetics. By replacing ethylene carbonate (EC) with difluoroethylene carbonate (DFEC) or fluoroethylene carbonate (FEC) in a conventional carbonate electrolyte, we investigated the role of d–d interaction, particularly inductive and dispersion forces, in regulating the solvation structure and (electro)chemical properties of a fluorocarbonate‐based WSE. DFEC exhibits inductive forces similar to those of FEC, yet exerts much stronger dispersion forces on linear carbonate molecules due to its greater molecular polarizability. Consequently, electrons redistribute toward the carbonyl oxygen atom of linear carbonates, and hydrogen atoms shift toward DFEC, as is verified by ¹⁷ O nuclear magnetic resonance spectroscopy and liquid‐phase time‐of‐flight secondary ion mass spectrometry. Much enhanced Li ⁺ ‐carbonate coordination further results in a high ionization degree yet sluggish desolvation kinetics of DFEC‐based WSE. In contrast, FEC‐based WSEs restore balanced weakly‐solvated behavior and lead to much improved battery performance at −20°C and −40°C. This study provides new insights into electrolyte chemistry and establishes general design principles for electrolytes capable of working under extreme conditions.