Amide Monomer-Mediated Solubilization Strategy Enables Nonflammable Deep Eutectic Gel Polymer Electrolytes for High-Temperature-Stable Lithium Metal Batteries.

Abstract

Deep eutectic gel polymer electrolytes (DEGPEs), combining intrinsic non-flammability with outstanding thermal stability, are attractive candidates for next-generation lithium metal batteries (LMBs). However, their practical deployment in high-energy-density LMBs has been fundamentally constrained by poor interfacial stability with the lithium metal anode and limited tolerance toward the high-voltage cathode. We report a new amide-monomer-mediated DEGPE that achieves comprehensive performance via a LiNO₃ solubilization strategy. The N-methylacrylamide (NME) units in the poly(N-methylacrylamide) (PNME) framework enhance LiNO₃ solubility through hydrogen bonding and Li⁺ coordination, forming a stable inorganic-rich interphase. Concurrently, it immobilizes free N-methyltrifluoroacetamide (NMTFA) via hydrogen bonds, suppressing transition-metal dissolution and preventing electrolyte leakage. The amide monomer-mediated DEGPE-based NCM811||Li cells achieve 80.1% capacity retention after 500 cycles with an average Coulombic efficiency of 99.67%, a performance that surpasses state-of-the-art (deep eutectic electrolyte) DEE-based systems. More impressively, LCO||Li cells retain 89.6% capacity after 300 cycles even at an elevated temperature of 80°C, far exceeding the thermal stability limits of conventional electrolytes and underscoring its remarkable interfacial stability under extreme operational conditions. This work establishes a molecularly engineered solvation and interfacial regulation strategy for DEGPEs, providing both fundamental insight and a practical pathway toward safe, high-energy, and high-temperature-tolerant LMBs.