Harnessing Li-Ion Binding Energy for Solvation-Guided Electrolyte Additive Design and Robust Solid Electrolyte Interphase Reinforcement.

The rational design of electrolyte systems is essential for stabilizing the electrode-electrolyte interface to enhance the electrochemical performance of lithium-ion batteries (LIBs). Although conventional strategies focus on the introduction of specific functional moieties, the correlation between the molecular structure of an electrolyte additive and the extent of effective localized enrichment at the interface remains poorly understood. Herein, we propose a solvation-guided additive design strategy in which the Li-ion binding energy of the additive serves as a factor for effective solid electrolyte interphase (SEI) reinforcement. This hypothesis is validated by employing a σ-bonding-insulation-based model system, which contains allyl methyl sulfone (AMS), allyl methyl carbonate (AMC), and allyl methyl ether (AME) as electrolyte additives with varying Li-ion binding affinities. Computational simulations and spectroscopic analyses confirmed that AMS, which has the highest binding energy, preferentially participates in the Li-ion solvation shell. This affinity, which facilitates the spontaneous migration of the additive toward the negative electrode during the SEI formation step, results in the development of a robust SEI layer concentrated at the negative electrode. These findings highlight the importance of interactions between Li-ions and additives in interface engineering and provide a systematic framework for the development of high-performance electrolyte additives.