Operation of Li-ion batteries below −20 °C is hindered by low electrolyte conductivity and sluggish solid-state diffusion in electrodes. Li metal anodes show promise for low-temperature operation, but few electrolyte compositions exhibit high conductivity at reduced temperature while also allowing Li electrodeposition/stripping with high Coulombic efficiency. Here, we show that the Coulombic efficiency of Li metal anodes can be substantially improved at low temperatures (−60 °C) by tailoring the solid-electrolyte interphase (SEI) structure through the use of two classes of electrolyte solvents: cyclic carbonates and ethers. Cryogenic transmission electron microscopy and other methods show that fluoroethylene carbonate (FEC) induces temperature-dependent changes in the chemistry and structure of the SEI to be abundant with LiF and Li₂CO₃, while ¹⁷O nuclear magnetic resonance and molecular dynamics calculations show that FEC affects the solvation behavior and SEI formation process in this new electrolyte system. Our results demonstrate the promise of rechargeable Li-metal batteries to enable energy storage over a broad temperature range.

中文翻译：

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量身定制固体电解质相间有效的锂金属阳极低温循环

电解质电导率低和电极中的固态扩散缓慢会阻碍锂离子电池在-20°C以下的运行。锂金属阳极显示了在低温下运行的希望，但是很少有电解质组合物在降低的温度下显示出高电导率，同时还允许以高库仑效率进行锂电沉积/剥离。在这里，我们表明，通过使用两类电解质溶剂：环状碳酸酯和醚类，通过调整固体-电解质中间相（SEI）结构，可以在低温（−60°C）下显着提高锂金属阳极的库仑效率。 。低温透射电子显微镜和其他方法表明，碳酸氟乙烯酯（FEC）诱导SEI的化学和结构中温度依赖性变化，因此LiF和Li含量较高。₂ CO ₃，而¹⁷ O核磁共振和分子动力学计算表明，FEC影响了这种新电解质系统的溶剂化行为和SEI形成过程。我们的结果表明，可充电锂金属电池有望在较宽的温度范围内进行能量存储。