β-Fluorination of Sulfolane: Redefining Solvation and Interphase Chemistry

Polar aprotic solvents such as sulfolane face challenges in forming stable, inorganic-rich interphases for high-voltage batteries. We show that β-fluorination of sulfolane reconstructs molecular orbitals to alter reductive pathways and generate stable interfacial components, while also redesigning bulk solvent structure via nonclassical hydrogen bonding. The resulting 3-fluorotetrahydrothiophene-1,1-dioxide (FSL) forms an extended hydrogen-bonded network that persists in solution, promoting the anion participation in the Li + solvation shell. Consequently, FSL and PF 6 – undergo coupled decomposition on Li metal anodes, forming interphases rich in LiF, Li 2 S, and sulfates. Fluorination also enhances FSL adsorption on NCM811 cathodes, ensuring exceptional cycling stability. This work establishes fluorine as a supramolecular director for electrolyte engineering.