Interphase‐Designable Additive‐Enabled Ethylene Carbonate‐Free Electrolyte for Wide‐Temperature, Long‐Cycling, High‐Voltage Lithium Metal Batteries

Abstract

AbstractIncreasing the upper cut‐off voltage of the LiNixCoyMn1‐x‐yO2 (NCM)‐based lithium‐metal batteries (LMBs) is highly pursued for achieving high battery energy density. However, the cycling stability of high‐voltage LMBs, which is associated with ethylene carbonate electrolytes, remains greatly challenging. Herein, an interphase‐designable additive‐enabled ethylene carbonate‐free electrolyte strategy is proposed for achieving 4.6 V Li||NCM811 battery with long cycling life from 55 to −30 °C. The solvent characteristics of ethyl methyl carbonate endow LMBs with potential merits in high voltage, wide temperature, and cycling stability, which are further strengthened by the additive, 1,5‐difluoro‐2,4‐dinitrobenzene (FNB), for optimizing electrode electrolyte interphases. The sturdy LiF‐rich and LiNxOy‐contained electrode/electrolyte interphase on cathode/anode surfaces can protect two electrodes well from electrolyte corrosion and also reduce excessive electrolyte decomposition. As expected, the Li||NCM811 batteries can maintain 70% capacity retention after 500 cycles with superior high‐temperature and low‐temperature performance (from 55 to −30 °C). The 6.8Ah pouch cells with this electrolyte can achieve a high energy density of up to 505 Wh kg−1.