Trilogy design of cross-linked polyether electrolytes for high-voltage and wide-temperature lithium metal batteries

In situ fabricated polyether electrolytes have been considered to be particularly promising for (quasi) solid-state Li-metal batteries (LMBs) owing to their excellent interfacial contact and fully compatible to commercial battery manufacture lines. However, their practical application in high-voltage and wide-temperature LMBs is restricted by poor oxidation stability, insufficient ionic conductivity, and instability of the interphases. Herein, a trilogy electrolyte design strategy was rationally proposed to enable high-voltage and wide-temperature LMBs, where (1) the molecular structure of liquid monomer is tuned from conventional 1,3-dioxolane to tetrahydrofuran (THF) with a high C/O ratio to form large distance for adjacent O atoms in the main chain, elevating the oxidation stability to 4.9 V; (2) the cross-linker with rich O sites is introduced to regulate the cross-linked hopping sites to enable rapid Li + transport, bestowing markedly high ionic conductivity of 3.3 mS cm −1 at 25 °C; and (3) the LiDFOB is employed to not only initiate polymerization but also generate highly robust and conductive inorganic-rich interphases. Hence, this cross-linked poly(THF) electrolyte endows highly stable operation of 4.5 V Li||LiNi 0.8 Co 0.1 Mn 0.1 O 2 and Li||LiCoO 2 batteries under a wide temperature range of −40 to 55 °C, representing the pioneering work reported thus far.