Universal Copolymerization of Crosslinked Polyether Electrolytes for All-Solid-State Lithium-Metal Batteries

Abstract

Solid polymer electrolytes (SPEs) are pivotal in advancing the practical implementation of all-solid-state batteries. Poly(1,3-dioxane) (PDOL)-based electrolytes have attracted significant attention due to the pseudo-high conductivity achieved through sophisticated in situ polymerization methods; however, such PDOL-based electrolytes present challenges of crystallization over time and monomers residual during processing. In this study, integrating LiTFSI and LiDFOB as a universal copolymerization strategy for developing high-performance PDOL electrolytes with a wide range of epoxy crosslinkers is proposed. It is discovered that this approach leverages the protective effects of TFSI anions on the boron active center and catalyzes polymer chain growth via crosslinking. The homogenously crosslinked (benzene-centered) PDOL electrolyte exhibits remarkable thermo-mechanical stability (up to 100 °C), high ion migration number (tLi+ = 0.42), a wide electrochemical window (≈5.0 V vs Li+/Li), and high ionic conductivity (4.5×10−4 S cm−1). Notably, the crosslinked PDOL electrolyte is in the all-solid-state with minimal monomer/oligomer residual, exhibiting no crystallization during relaxation, delivering a robust performance in all-solid-state lithium metal batteries.