Kinetics‐Optimized Crown Ether Engineering Enables Ultra‐Flat Lithium Metal Interface for Long‐Cycling 532 Wh Kg ⁻¹ Pouch Cells

Lithium (Li) metal batteries are plagued by erratic electrodeposition and unstable interphases. Achieving balanced Li ions (Li⁺) nucleation and diffusion kinetics is pivotal to address these obstacles and secure durable, uniform deposition. Herein, we present a molecular design strategy that decouples these competing demands by engineering a leveling agent with moderate coordination and dynamic Li⁺ transport. By replacing oxygen donors with secondary amine in a macrocyclic framework, we demonstrate that aza-12-crown-4-ether (N-12-4) exhibits precisely tuned adsorption toward Li⁺ ions. This tailored interaction enables a self-leveling deposition mechanism, homogenizing electric fields while maintaining rapid ion transport. Consequently, Li||LiFePO₄ full cells deliver a practical areal capacity of 3.63 mAh cm⁻², retaining 99.7% capacity after 100 cycles. Meanwhile, the strategy is validated in 7.5 Ah Li pouch cells, which deliver an energy density of 532 Wh kg⁻¹ while retaining 84% of the initial capacity after 170 cycles. Beyond lithium metal batteries, this strategy can be extended to the rational tuning of coordination strength in macrocyclic supramolecular systems and is potentially applicable to other metal-based battery chemistries.