Ion bridging enables high-voltage polyether electrolytes for quasi-solid-state batteries
Tianyi Hou, Donghai Wang, Bowen Jiang, Yi Liu, Jia Kong, Yan‐Bing He, Yunhui Huang, Henghui Xu
Abstract
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. The application of polyether electrolytes for Li-ion batteries is limited by their poor oxidative stability. Here, authors report an ion-bridging approach to extend their oxidation potential by stabilizing lone pairs of ethereal oxygen through Zn2+−O coordination.