Sub‐Nano Confinement Engineering Toward Anion‐Reinforced Solvation Structure to Achieve Highly Reversible Anode‐Free Lithium Metal Batteries

The practical application of anode‐free lithium metal batteries (AFLMBs) is impeded by poor cycling performance due to sluggish Li + transport kinetics, unfavorable side reactions, and dendrite Li growth. To address these issues, ≈200 nm zeolitic imidazolate framework‐8 (ZIF‐8) interphase layer is introduced to enable highly reversible Li plating/stripping by electrosynthesis method. ZIF‐8 interphase layer with sub‐nano windows accelerates Li + desolvation kinetics and thus suppresses unfavorable side reactions. Further, the internal cavities of ZIF‐8 serve as an anion reservoir to modulate anion‐reinforced solvation structure of Li + , facilitating the formation of LiF‐ and Li 3 N‐riched solid–electrolyte interphase. Thus, the Li/Cu@ZIF‐8 asymmetric cell exhibits remarkable Aurbach coulombic efficiency of 99.84%, and Cu@ZIF‐8/LiFePO 4 AFLMB delivers impressive capacity retention (57.8%) over 400 cycles. This work highlights the effectiveness of ZIF‐8 to enable highly reversible AFLMBs and inspires the potential application of porous materials with sub‐nano windows and interval cavities in anode‐free batteries.