Nitrobenzo Crown Ether Enables Stable Interphases in Lithium Metal Batteries

Lithium metal anodes promise high‐energy‐density storage but suffer from unstable solid electrolyte interphases and dendrite growth in carbonate electrolytes. Here, 4‐nitrobenzo‐15‐crown‐5 ether (NBCE) is introduced as a multifunctional electrolyte additive that simultaneously regulates Li + solvation and interfacial chemistry. NBCE replaces ethylene carbonate in the Li + solvation sheath, increasing contact ion pairs and substantially lowering the Li + desolvation energy. Its preferential reduction on lithium, accompanied by conversion of the nitro group into Li 3 N, produces a dense LiF‐ and Li 3 N‐rich SEI. Consequently, Li||Cu cells exhibit higher Coulombic efficiency (CE), lower nucleation overpotential, and dense, dendrite‐free lithium deposition, while Li||Li symmetric cells cycle stably for over 1000 h. Li||NCM811 full cells retain 79.5% of their capacity after 300 cycles with an average CE of 99.5%, and deliver approximately 86 mAh g −1 at 5 C. NBCE also significantly suppresses leakage current at high voltages. These findings establish multifunctional solvation and interphase regulation as an effective electrolyte‐design strategy for high‐energy‐density lithium metal batteries.