Manipulating the Host−Guest Chemistry of Cucurbituril to Propel Highly Reversible Zinc Metal Anodes

Abstract Rechargeable aqueous zinc‐ion batteries are practically plagued by the short lifespan and low Coulombic efficiency (CE) of Zn anodes resulting from random dendrite deposition and parasitic reactions. Herein, the host−guest chemistry of cucurbituril additive with Zn 2+ to achieve longstanding Zn anodes is manipulated. The macrocyclic molecule of cucurbit[5]uril (CB[5]) is delicately designed to reconstruct both the CB[5]‐adsorbed electric‐double layer (EDL) structure at the Zn interface and the hydrated sheath of Zn 2+ ions. Especially benefiting from the desirable carbonyl rims and suitable hydrophobic cavities, the CB[5] has a strong host−guest interaction with Zn 2+ ions, which exclusively permits rapid Zn 2+ flux across the EDL interface but retards the H 2 O radicals and SO 4 2− . Accordingly, such a unique particle redistributor warrants long‐lasting dendrite‐free deposition by homogenizing Zn nucleation/growth and significantly improved CE by inhibiting side reactions. The Zn anode can deliver superior reversibility in CB[5]‐containing electrolyte with a ninefold increase of cycle lifetime and an elevated CE of 99.7% under harsh test conditions (10 mA cm −2 /10 mA h cm −2 ). The work opens a new avenue from the perspective of host−guest chemistry to propel the development of rechargeable Zn metal batteries and beyond.