Vertically Aligned Metal–Organic Framework Arrays as Protective Layers for Durable Zinc Anodes with Low Overpotentials

Rechargeable aqueous zinc-ion batteries (ZIBs) are promising for large-scale energy storage due to their high safety and low cost, yet side reactions and dendrite growth limit their practicality. Although protective layers on Zn anodes can address these issues, conventional protective layers containing polymer binders often hinder Zn²⁺ transport and Zn deposition/dissolution. In this study, we develop a ligand-induced morphological regulation strategy via an electrodeposition approach to directly fabricate binder-free metal-organic frameworks (MOFs) as protective layers on Zn anodes, including vertically aligned MOF arrays on Zn (VAA-ZnTMA@Zn), shaggy horizontal nanosheets on Zn (SHN-ZnMI@Zn), and compact nanoparticles on Zn (CNP-ZnTPA@Zn). Among them, the VAA-ZnTMA@Zn electrode exhibits an ultralow overpotential of 20 mV and an extended cycle life of up to 2400 h. Moreover, the VAA-ZnTMA@Zn//MnO₂@CC full cell exhibits exceptional durability with high average Coulombic efficiency of 99.6% and a capacity retention of 82% after 2000 cycles at 1 A g^-1. Through electrochemical analyses, theoretical calculations, and finite element simulations, it is revealed that the vertically aligned MOFs channels, uniform electrical field distribution, and abundant deposition sites in VAA-ZnTMA@Zn facilitate accelerated Zn²⁺ transport and uniform Zn deposition, effectively suppressing dendrite formation. This work provides an efficient route toward durable Zn anodes for aqueous ZIBs.