Polyether-based composite solid-state electrolyte to realize stable high-rate cycling for high-voltage lithium metal batteries at room temperature

Polyether electrolytes, which possess benefits in terms of lithium salt solubility, compatibility with lithium metal, and material availability, are promising candidate materials for solid-state lithium metal batteries with high safety and specific energy. However, achieving stable cycling at high rates under room temperature conditions for high-voltage lithium metal solid-state batteries is a significant challenge. In this study, a polyether-based composite solid-state electrolyte was fabricated via in situ polymerization, and a novel polyether matrix (PDSi) was synthesized by copolymerization of 1,3-dioxolane (DOL) and 3-(glycidoxypropyl)triethoxysilane (GPTES). The triethoxysilicon groups of PDSi improve the antioxidant capacity of polyether and interact with anionic groups, thereby enabling a wide electrochemical window of 5.5 V and a high lithium-ion transference number tLi+ of 0.56 at room temperature. In addition, a prepared PDSi@LLZTO electrolyte with an asymmetric structure mitigated the side reaction between the LLZTO ceramic filler and lithium. Here, PDSi@LLZTO exhibited a lithium-ion transference number of 0.67 and ionic conductivity of 1.28 × 10−4 S cm−1 at 20 °C. More importantly, the Li|PDSi@LLZTO|NCM523 cell demonstrated excellent capacity retention of 83.9 % after 200 cycles at a high-rate discharge of 3C. The proposed material and structure design provide a unique perspective for the development of an effective polymer-based electrolyte for high-voltage lithium metal batteries.