Dynamic Networks via Polymerizable Deep Eutectic Monomers for Uniform Li<SUP>+</SUP> Transport at Interfaces in Lithium Metal Batteries

Abstract

Solid polymer electrolytes (SPEs) offer an appealing alternative to volatile and flammable organic liquid electrolytes for high-energy lithium metal batteries (LMBs). Despite their potential, two key challenges, insufficient ionic conductivity and inadequate interfacial performance, continue to hinder practical development. Here, the promising potential of a single-ion conducting gel polymer electrolyte (SIGPE) derived from a polymerizable deep eutectic monomer (PDEM) is demonstrated. This structure forms dynamic nanophases with a high-dielectric-constant dielectricizer through Li+-bridged molecular self-association within a flexible polymer matrix. This design regulates ion pathways to enable rapid Li+ conduction, effectively preventing interfacial polarization and promoting ion dissociation, while also exhibiting viscoelastic properties that strengthen interface stability. The resultant SIGPE exhibits a high oxidation voltage of 5.0 V and a near-unity transference number of 0.86. In the LFP|SIGPE|Li full cell, the formation of an inorganic-rich SEI layer, driven by hetero species (Li2O/LiF), enables a high discharge capacity of 131.9 mAh g-1 at 1 C and stable cycling performance, with 71.9% capacity retention and 99.5% coulombic efficiency after 400 cycles at 1 C and 30 degrees C. These findings underscore the potential of PDEM-based SIGPE to enhance performance, safety, and sustainability in LMBs, paving the way for practical use in high-energy storage systems.