Synthesis of a crosslinked ether-based polymer for high-performance semi-solid lithium metal batteries via in situ integration

Abstract

In situ ring-opening polymerization of ether-based monomers has shown promising application in solid-state lithium metal batteries owing to their positive lithium compatibility, mild reaction conditions, and facile preparation. However, typical poly(1,3-dioxolane) (PDOL) based electrolyte still struggles with low ionic conductivity, narrow electrochemical window, and poor thermal stability, which greatly retard its further progress. Herein, we constructed a crosslinked PDOL semi-solid electrolyte initiated by a three-armed crosslinker and high voltage resistant fluorinated solvents, which shows favourable stability toward lithium metal (lithium plating/stripping stably operating for 2700 h at 0.2 mA cm⁻² with no significant polarization growth) and a high electrochemical oxidation window of up to 4.6 V. A lithium metal coin cell using this crosslinked semi-solid electrolyte equipped with LFP expresses excellent cycling stability with a capacity retention of 88% for 1000 cycles at 1C. A 50 mA h pouch cell with an NCM811 cathode exhibited favourable working ability. Meanwhile, the crosslinked electrolyte demonstrated better solid-state characteristics and thermal stability compared with a long-chain electrolyte. This work provides a prospective reference for the application of ether-based electrolyte in high safety and high energy density lithium metal batteries.