The stable operation of solid-state lithium metal batteries at low temperatures is plagued by severe restrictions from inferior electrolyte-electrode interface compatibility and increased energy barrier for Li migration. Herein, we prepare a dual-salt poly(tetrahydrofuran)-based electrolyte consisting of lithium hexafluorophosphate and lithium difluoro(oxalato)borate (LiDFOB). The Li-salt anions (DFOB) not only accelerate the ring-opening polymerization of tetrahydrofuran, but also promote the formation of highly ion-conductive and sustainable interphases on Li metal anodes without sacrificing the Li conductivity of electrolytes, which is favorable for Li transport kinetics at low temperatures. Applications of this polymer electrolyte in Li||LiFePO cells show 82.3% capacity retention over 1000 cycles at 30 °C and endow stable discharge capacity at −30 °C. Remarkably, the Li||LiFePO cells retain 52% of their room-temperature capacity at −20 °C and 0.1 C. This rational design of dual-salt polymer-based electrolytes may provide a new perspective for the stable operation of quasi-solid-state batteries at low temperatures.

中文翻译：

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双盐聚四氢呋喃电解质使准固态锂金属电池能够在-30℃下工作


固态锂金属电池在低温下的稳定运行受到电解质-电极界面兼容性差和锂迁移能垒增加的严重限制。在此，我们制备了由六氟磷酸锂和二氟草酸硼酸锂（LiDFOB）组成的双盐聚（四氢呋喃）基电解质。锂盐阴离子（DFOB）不仅加速四氢呋喃的开环聚合，而且促进在锂金属负极上形成高离子传导性和可持续的界面相，而不牺牲电解质的锂电导率，这有利于锂传输低温下的动力学。这种聚合物电解质在Li||LiFePO电池中的应用显示，在30°C下1000次循环后容量保持率为82.3%，并在-30°C下具有稳定的放电容量。值得注意的是，Li||LiFePO电池在-20°C和0.1C下保留了52%的室温容量。这种基于双盐聚合物的电解质的合理设计可能为准固体的稳定运行提供新的视角。 - 低温状态下的电池。