Polymer electrolytes with high ionic conductivity, good interfacial stability and safety are in urgent demand for practical rechargeable lithium metal batteries (LMBs). Herein we propose a novel flame-retardant polymerized 1,3-dioxolane electrolyte (PDE), which is in situ formed via a multifunctional tris(pentafluorophenyl)borane (TB) additive. The in situ formed PDE not only affords an integrated battery structure with stabilized electrode–electrolyte interface, but also achieves good flame retardancy, significantly expanded operating temperature limit and improved oxidative stability. Moreover, TB also contributes to a highly stable LiF-rich solid electrolyte interphase (SEI). In addition, the PDE has good compatibility with electrodes and polypropylene (PP) separator, hardly increasing the thickness of the battery, and the amount of additive TB is small, so there is no loss of gravimetric or volumetric energy density due to the polymerization. Based on the in situ formed PDE, Li–S batteries without the addition of LiNO₃ demonstrate excellent cycle stability (>500 cycles) and a wide operating temperature (−20 to 50 °C); the high voltage Li–LiNi_0.6Co_0.2Mn_0.2O₂ and Li–LiFePO₄ batteries both exhibit excellent electrochemical performance (>1200 cycles). In addition, the ultrasonic imaging technique developed by our group also demonstrates no gas generation inside pouch cells using PDE. This work provides a facile and practical approach to design a highly stable polymer electrolyte for high performance LMBs.

中文翻译：

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用于扩展工作温度的高性能锂金属电池的阻燃聚合物电解质

对于实用的可再充电锂金属电池（LMB），迫切需要具有高离子传导性，良好的界面稳定性和安全性的聚合物电解质。本文中，我们提出了一种新型的阻燃聚合1,3-二氧戊环电解质（PDE），它是通过多功能三（五氟苯基）硼烷（TB）添加剂原位形成的。在原位形成的PDE不仅提供了具有稳定的电极-电解质界面的集成电池结构，而且还实现了良好的阻燃性，显着扩展的工作温度极限并改善了氧化稳定性。此外，TB还有助于实现高度稳定的富LiF固体电解质中间相（SEI）。另外，PDE与电极和聚丙烯（PP）隔板具有良好的相容性，几乎不增加电池的厚度，并且添加剂TB的量很小，因此不会由于聚合而损失重量或体积能密度。基于原位形成的PDE，不添加LiNO _3的Li–S电池表现出出色的循环稳定性（> 500次循环）和宽工作温度（−20至50°C）；高压Li–LiNi _0.6 Co _0.2 Mn _0.2 O ₂和Li–LiFePO ₄电池均具有出色的电化学性能（> 1200次循环）。此外，我们小组开发的超声成像技术还证明使用PDE不会在袋状细胞内部产生气体。这项工作为设计用于高性能LMB的高度稳定的聚合物电解质提供了一种简便实用的方法。