Tertiary Amide Deep Eutectic Gel Electrolyte Eliminates Hydrogen Evolution and Enables Safe, Wide‐Temperature Lithium Metal Batteries

Abstract

ABSTRACT Deep eutectic gel electrolytes (DEEs) based on amide‐Li + Lewis acid‐base coordination are promising for lithium metal batteries, yet they suffer from parasitic hydrogen evolution from reactive N‐H groups, poor interfacial stability, and inherent flammability. Here, we report a rationally designed tertiary amide deep eutectic gel electrolyte (PLDF‐GPE) by replacing conventional primary/secondary amides with N, N‐diethyltrifluoroacetamide and N, N‐dimethylacrylamide, thereby eliminating active N‐H hydrogen atoms, suppressing hydrogen evolution at the Li anode interface while maintaining a robust C═O…Li + coordination network that ensures deep eutectic behavior. The tertiary amide design exhibits a temperature‐responsive solvation structure that dynamically adjusts Li + coordination to lower desolvation barriers, enabling stable operation over a wide temperature range (−20°C to 80°C). Crucially, the fluorine‐ and nitrogen‐rich components preferentially decompose to form a LiF/Li 3 N‐enriched SEI/CEI that enhances interfacial compatibility. Moreover, PLDF‐GPE generates N─C═O• and F• radicals during combustion, which combine with active hydrogen radicals (H•) and impart intrinsic non‐flammability. Consequently, Li||Li symmetric cells achieve 1800 h of stable cycling, Li||NCM811 cells retain 65.7% capacity after 600 cycles at 0.25 C, and Li||LiFePO 4 cells operate reliably at an extreme temperature of 160°C. This molecular design strategy offers a transformative pathway toward safe, wide‐temperature lithium metal batteries.