Additive‐guided Solvation‐regulated Flame‐retardant Electrolyte Enables High‐voltage Lithium Metal Batteries with Robust Electrode Electrolyte Interphases

Abstract Widening the voltage window of the nickel‐rich layered oxide cathode‐based lithium metal batteries (LMBs) can effectively improve the energy density of rechargeable batteries. However, serious safety issues associated with the high reactivity between LiNi 0.8 Co 0.1 Mn 0.1 O 2 (NCM811) and electrolyte at high cut‐off voltage remains challenging. Herein, a flame‐retardant electrolyte with the ability to form a robust armor‐like electrode electrolyte interphase (EEI) with LiF and Li x B y O z compounds for stabilizing Li||NCM811 batteries is proposed. Such electrolyte exhibits the high thermal stability with flame‐retardant effect for ensuring the battery safety at high voltage. The armor‐like EEI can effectively protect both NCM811 and lithium (Li) for improving the battery cycling performance. As a result, the capacity retention rate of the NCM811 cathode with such electrolyte reached 68% after 150 cycles at 4.6 V. This work provides an effective reference for the reasonable design of high‐voltage, flame‐retardant electrolytes for LMBs.