In-situ construction of solid polymer electrolyte with regulated Li-polymer interaction for high-performance solid-state Li metal batteries

Abstract

The practical application of lithium metal batteries (LMB) is severely hindered owing to the fatal side reactions and dendritic growth of Li, while the development of solid-state LMB by using solid polymer electrolytes (SPE) can address these issues. Employing in-situ polymerization method is a feasible strategy for the large-scale production of SPE. However, its ionic conductivity and high voltage stability is still unsatisfactory. Herein, we developed a new SPE based on the in-situ polymerization of 2-vinyl-1,3-dioxolane (VDOL). The double bond addition reaction of VDOL induced by free radical polymerization endows the formation of enriched adjacent carbonyl functional group in polymer chain, which significantly enlarges its high-voltage tolerance and facilitates the formation of densified sites for favored Li⁺ interaction and promoted ion conduction. In addition, the strengthened chemical interaction between Li⁺ and C-O groups in SPE not only enhances the lithium salt dissociation, but also effectively regulates Li deposition and immobilizes anions. Attributed to its regulated Li-polymer interaction, the designed Ah-level pouch type LMB paired with sulfur cathode demonstrates a high energy density of 314.8 Wh kg⁻¹ and decent cyclic stability, which provides a new strategy of developing high performance SPE and related electrochemical devices.