Ion bridging enables high-voltage polyether electrolytes for solid-state batteries

Polyether electrolytes have been widely recognized for their favorable compatibility with lithium-metal, yet they are hampered by intrinsically low oxidation thresholds, limiting their potential for realizing high-energy Li-metal batteries. Here, we report a general approach involving the bridge joints between non-lithium metal ions and ethereal oxygen, which significantly enhances the oxidation stability of various polyether electrolyte systems. To demonstrate the feasibility of the ion-bridging strategy, a Zn2+ ion-bridged polyether electrolyte (Zn-IBPE) with an extending electrochemical stability window of over 5 V is prepared, which enables good cyclability in 4.5 V Li||LiCoO2 batteries. Ampere-hour-level quasi-solid-state batteries of SiO-graphite||LiNi0.8Mn0.1Co0.1O2 (10 Ah, N/P ratio of 1.12, 303 Wh kg−1 at 0.1 C based on the total weight of the pouch cells) and 60 μm-Li||LiNi0.9Mn0.05Co0.05O2 (18 Ah, N/P ratio of 2.5, 452 Wh kg−1 at 0.33 C based on the total weight of the pouch cells) pouch cells with Zn-IBPE present elevated electrochemical performance, benefiting from adequate interfacial stability. Nail penetration tests evidence high battery safety enabled by Zn-IBPE in 4 Ah graphite||LiNi0.8Mn0.1Co0.1O2 pouch cells without combustion or smoke. This work offers a pathway for designing high-voltage polymer electrolytes and a general solution for achieving high-performance quasi-solid-state batteries.

聚醚电解质（polyether electrolytes）已被广泛证实与锂金属具备优异的界面相容性，但其本征氧化电位阈值偏低，掣肘了其在高能量密度锂金属电池中的应用前景。本研究提出一种普适性策略，通过构建非锂金属离子与醚氧之间的桥联结构，显著提升了各类聚醚电解质体系的氧化稳定性。为验证离子桥联策略的可行性，本研究制备得到氧化稳定窗口拓展至5 V以上的Zn²+离子桥联聚醚电解质（Zn-IBPE），该电解质可在4.5 V规格的Li||LiCoO₂电池中实现优异的循环稳定性。采用Zn-IBPE的安培级软包准固态电池得益于充足的界面稳定性，展现出优异的电化学性能：其中SiO-石墨||LiNi₀.₈Mn₀.₁Co₀.₁O₂软包电池容量达10 Ah，负极-正极容量比（N/P）为1.12，以软包电池总重量计，0.1 C倍率下的能量密度可达303 Wh·kg⁻¹；60 μm厚锂负极||LiNi₀.₉Mn₀.₀₅Co₀.₀₅O₂软包电池容量达18 Ah，N/P比为2.5，0.33 C倍率下能量密度可达452 Wh·kg⁻¹。针对4 Ah容量的石墨||LiNi₀.₈Mn₀.₁Co₀.₁O₂软包电池的针刺测试结果表明，Zn-IBPE可赋予电池极高的安全性能，测试过程中电池未发生燃烧或冒烟现象。本研究为高压聚合物电解质的设计提供了可行路径，同时为高性能准固态电池的开发提供了普适性解决方案。