Cerium-Mediated Redox Chemistry in MOF Coatings Enables Ultrastable Aqueous Zn Metal Batteries

Constructing artificial coatings on Zn metal anodes represents a promising approach to suppressing interfacial side reactions and enhancing reversibility for stable aqueous Zn metal batteries. Herein, Ce-mediated redox chemistry in Ce-UiO-66 MOF coating was explored to stabilize the aqueous Zn anode. We found that the Ce-UiO-66 coating facilitates multi-stage Zn 2+ desolvation due to its abundant carboxyl groups and an optimal porous structure. Moreover, the Ce 3+ /Ce 4+ redox-induced, abundant vacancies provide numerous zincophilic sites for preferential Zn 2+ adsorption and transport. Crucially, the reversible Ce 3+ /Ce 4+ redox behavior enables significant homogenization of electron/Zn 2+ distributions while accelerating interfacial charge transfer kinetics during repeated Zn plating/stripping. Consequently, a Zn anode with an optimal ∼5 µm Ce-UiO-66 coating achieves exceptional stability, highlighted by an ultralong cycling life exceeding 6000 h at 2.0 mA cm −2 and 1.0 mAh cm −2 , alongside an ultralow polarization voltage of ∼24 mV. High-rate stability over 2800 h is also maintained at 5.0 mA cm −2 and 1.0 mAh cm −2 . This work underscores the great potential of redox-active coatings, specifically leveraging Ce-mediated redox chemistry, to enable highly stable aqueous Zn metal batteries for practical applications.