Regulating Ion Transport through Direct Coordination in Composite Gel Polymer Electrolytes towards High‐voltage and High‐loading Quasi‐solid‐state Lithium Metal Batteries

Abstract

Poly(ethylene oxide)‐based composite gel polymer electrolyte is widely used in lithium metal batteries to address dendrite growth and side reactions. However, the low oxidative decomposition potential (< 4 V) of poly(ethylene oxide) limits the cyclic stability with Ni‐rich layered cathodes. What’s more, poor interface compatibility between fillers and polymer severely deteriorates lithium‐ion pathways, which cannot achieve lithium metal batteries with high‐load cathode. Herein, polyether monomers coordinate with aluminum ethoxide nanowires via in‐situ ultraviolet curing, stabilizing the lone pair electrons of ethereal oxygen atoms and suppressing oxidative degradation. This coordination also forms abundant and tight interfaces as the predominant lithium‐ion conduction pathways, contributing to ordered lithium‐ion fluxes and dendrite‐free deposition on the lithium anode. In addition, a robust solid electrolyte interphase containing aluminum‐based species enhances the interfacial stability of lithium anode. Meanwhile, the good compatibility between the electrolyte and the cathode effectively suppresses side reactions and contributes to the structural stabilization of the cycled cathode. The delicate design allows the Li||LiNi0.6Co0.2Mn0.2O2 cells to present excellent cycling stability from −20 oC to 60 oC. Specially, cells with 8.8 mg cm−2 cathode cycle stably for over 120 cycles. This molecular structure engineering will greatly promote the practical application of solid‐state lithium metal batteries.