Regulating Lithium Plating Behavior in Lithium‐Metal Batteries via Molten‐Lithium Processing With Inorganic Additives

Lithium metal batteries (LMBs) are compelling candidates for next‐generation energy storage owing to the ultrahigh theoretical capacity (3,860 mAh g −1 ) and high energy density (400–500 Wh kg −1 ). However, uncontrollable dendrite growth, severe volume change, low Coulombic efficiency, and the poor lithiophilicity of Cu current collectors have impeded practical deployment. Here, we report a self‐assembled gradient interphase (SGI) produced in situ by reacting molten lithium with ZnF 2 . The SGI exhibits a self‐formed, vertically graded architecture. The SGI consists of a LiZn alloy sublayer that lowers nucleation overpotential and accelerates Li + transport, and a LiF layer that offers high ionic conductivity and outstanding air stability for durable interfacial stability. The lower LiZn alloy layer promotes uniform lithium nucleation by providing a low diffusion barrier and strong interfacial affinity, while the upper LiF layer forms a stable, inorganic SEI that effectively suppresses dendrite growth. The symmetric cell equipped with the SGI Li–Zn–F interphase exhibited highly durable cycling, maintaining stable operation for 3000 h under 4 mA cm −2 /16 mAh cm −2 . This dual‐layer configuration, in which distinct functional roles are spatially separated within the interphase, offers an advantage not attainable with conventional single‐layer coatings.