Micelle‐Like Electrolyte Design for 4.6 V Li||NCM811 Cells Workable at 70 °C

Abstract Localized high‐concentration electrolytes (LHCE) feature satisfactory anode compatibility for lithium (Li)‐metal batteries (LMBs). However, their application under high charging cut‐off voltages and elevated temperatures still remains limited due to the electrochemical and thermal instabilities of solvents within the solvation sheath. Herein, we design a micelle‐like electrolyte (QMLE) with a low anion‐to‐solvent ratio (0.3) and diluent‐to‐solvent ratio (1.3), achieved by regulating the length and type of non‐solvating alkyl and fluorinated segments grafted onto polar ethyltrimethoxysilane (ETMOS) solvents, pushing the performance boundaries of LHCE. In this electrolyte, strong intramolecular interactions from the −CF 3 anchoring segments not only markedly whittle the solvation ability of the ETMOS but also elevate its flash point, thereby facilitating the formation of the anion‐dominated solvation sheaths and the improvement of high‐temperature tolerance of the QMLE. With the help of the QMLE, Li||Cu cell delivers a high coulombic efficiency of 98.5% at 3 mA cm −2 and 3 mAh cm −2 . The newly assembled Li||NCM811 (11.5 mg cm −2 ) cell achieves stable operation under a high charging cut‐off voltage of 4.6 V and a high‐temperature range from 30 °C to 70 °C. This study presents a versatile and scalable electrolyte design strategy for high‐voltage and high‐temperature LMBs.