Sustainable Lignin‐Derived Cross‐Linked Graft Polymers as Electrolyte and Binder Materials for Lithium Metal Batteries

This study concerns the development of a well‐defined synthetic route to obtain lignin‐derived multifunctional graft polymers by simple chemical modification and atom‐transfer radical polymerization. By grafting ion‐conducting and cross‐linkable moieties onto the lignin, star‐shaped functional polymers are prepared. Upon cross‐linking under ultraviolet light irradiation, the resulting polymer network exhibits mechanical stability even at high temperature, whereas the chain mobility is maintained despite the cross‐linked structure. Their use as solid polymer electrolytes (SPEs) and binders for all‐solid‐state lithium metal batteries (LMBs) is also evaluated. The lignin‐derived graft polymers provide a facile ion conduction pathway and also efficiently suppress lithium dendrite growth during cycling, thereby attaining excellent cycling performance for the LMB cell compared to that with a conventional liquid electrolyte–Celgard system. Wishing on a star: A lignin‐derived star‐shaped polymer with ion‐conducting and cross‐linkable moieties is synthesized and used as a solid polymer electrolyte (SPE) and binder for lithium metal batteries. The all‐solid‐state lithium metal battery exhibits excellent cycling performance with great suppression of lithium dendrite growth. When the polymer is used as a binder with liquid electrolyte, cycling performance, especially at high current density, is greatly improved.