Abstract: The role of molecular-level noncovalent interactions (NCI) in governing solid electrolyte interphase (SEI) formation remains poorly understood. This study employs Density Functional Theory (DFT) combined with Reduced Density Gradient (RDG) analysis to investigate 18 solvent and additive molecules adsorbed on four inorganic SEI surfaces: Li₂CO₃(001), Li₂O(111), LiF(001), and LiOH(001). Interfacial interactions and electronic rearrangements were quantified via RDG analysis, differential charge densities, and Bader charge calculations. Results indicate that cyclic carbonates and sulfonyl/sultone groups exhibit strong directional attractions, whereas linear carbonates are dominated by weak van der Waals interactions, offering higher structural flexibility. Li₂O demonstrates the strongest interfacial polarization toward polar O- or S- containing molecules. Bader analysis reveals net charge transfers (∆Q) ranging from 0.440 to 0.798 e. Specifically, ethylene sulfite and 4,5-dimethyl-[1,3]dioxol-2-one on Li₂O yield the highest transfers (0.796 and 0.798 e), while dimethyl carbonate and propylene carbonate on Li₂CO₃ show significantly lower values (0.440 and 0.479 e). LiF displays weak overall adsorption but high compatibility with fluorinated molecules (e.g., fluoroethylene carbonate-LiF, 0.672 e), while LiOH exhibits moderate polarization (0.618-0.679 e).Strong directional NCI between polar additives and stable inorganic phases (Li₂O, LiF) provide the microscopic foundation for dense, stable SEI structures, whereas linear carbonates primarily facilitate wetting and stress buffering. This work elucidates electrolyte-SEI compatibility mechanisms, offering theoretical guidance for designing inorganic-rich SEI layers.

Key words: solid electrolyte interphase (SEI), density functional theory (DFT), noncovalent interaction analysis based on the reduced density gradient (NCI-RDG), interfacial charge transfer