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

مقال فى مجلة

Increasing 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.