Vinyl Silane‐Mediated Solvation Energetics Enable High‐Voltage Lithium‐Ion Batteries

Abstract Raising the charging cut‐off voltage (>4.3 V) is essential for increasing lithium‐ion battery energy density. However, the accelerated oxidation behavior of electrolytes at the interface driven by the electric field has not been resolved. Herein, the study introduces 2,2,7,7‐tetramethyl‐4‐vinyl‐3,6‐dioxa‐2,7‐disilaoctane (TVDD) as a multifunctional electric double‐layer (EDL) mediator into carbonate‐based electrolytes. As an electric field‐insensitive additive, TVDD strongly coordinates with Li⁺, while the steric hindrance from its dual trimethylsilyl (TMS) groups displaces carbonate solvents from the Li ⁺ solvation shell, enriching PF ₆ ⁻ at the interface and promoting anion‐dominated electrode‐electrolyte interphases (EEIs). Additionally, the dual TMS groups in TVDD scavenge HF, and the redox‐active vinyl group further stabilizes the EEI through in situ electrochemical polymerization, synergistically enhancing interfacial stability and kinetics. In practical applications, TVDD‐modified electrolytes enable a 500 mAh graphite (Gr) || LiNi _0.6 Co _0.1 Mn _0.3 O ₂ (NCM613) pouch cell to achieve 1200 cycles with 88.7% capacity retention at 2.8–4.4 V, significantly outperforming conventional electrolytes (74.2% retention after 1000 cycles). TVDD also enhances the electrochemical performance and stability in Gr || NCM613 and Gr || LiCoO ₂ pouch cells under 45 °C. This work presents a synergistic physicochemical approach for EDL regulation that combines steric shielding with redox‐active functionality to stabilize high‐voltage batteries, providing insights into the electrolyte chemistries.