Synergistic Coupling of Host and Electrolyte Achieving 1270 Wh L ⁻¹ in Anode‐Free Lithium Metal Batteries

Anode‐free lithium metal batteries (LMBs) represent a promising avenue for maximizing energy density by eliminating excess lithium (Li), yet their practical implementation is impeded by limited Li reversibility and pronounced interfacial instability. Herein, a synergistic coupling strategy is reported that integrates a highly reversible host (RH) with a rationally designed, carbonate‐rich electrolyte (DEL) to concurrently address these fundamental challenges. The RH spontaneously induces the formation of a robust Li 2 O‐ and Li 3 N‐rich solid electrolyte interphase via electron transfer, which effectively accommodates Li volume changes and suppresses dendritic growth. Complementarily, DEL, composed of commercially available salts, solvents, and additives, establishes stable electrode‐electrolyte interphases at both electrodes. Coin‐type anode‐free full cells employing the RH‐DEL configuration achieve an average Coulombic efficiency of 99.6% and 81.9% capacity retention after 100 cycles at 4.6 mAh cm −2 and 2.3 mA cm −2 . Stacked pouch‐type full cells further deliver a record volumetric energy density of 1270 Wh L −1 (including packaging) under lean electrolyte (E/C = 2.5 g Ah −1 ) and a low stack pressure (≈20 kPa). This synergistic approach delineates a practical pathway toward high‐energy, long‐life anode‐free LMBs for advanced energy storage systems.