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 PF6– undergo coupled decomposition on Li metal anodes, forming interphases rich in LiF, Li2S, 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.