ZnO Quantum Dots Packed with Functional Groups: A Smart Coating Layer for Dendrite-Free Aqueous Zinc-Ion Batteries

A nanostructured interfacial engineering strategy employing zinc oxide quantum dots (ZnOQD) is designed to stabilize Zn metal anodes (ZnOQD@Zn). Because of their ultrasmall size, intrinsic hydrophilicity, and abundant surface functional groups, the uniformly dispersed ZnOQD constructs a multifunctional interlayer that enables continuous Zn²⁺ transport, homogenizes interfacial ion flux, and lowers the energy barriers associated with Zn²⁺ desolvation and nucleation. Meanwhile, this interlayer suppresses dendrite growth, hydrogen evolution, and corrosion by limiting direct contact between Zn and water. As a result, the ZnOQD@Zn anode exhibits highly reversible Zn plating and stripping together with enhanced cycling stability. When assembled with a NaV₃O₈·1.5H₂O (NVO) cathode, the ZnOQD@Zn cell delivers excellent rate capability and long-term durability, even under high cathode loadings. This work presents a simple, scalable, and effective interfacial regulation strategy enabled by quantum dots, offering fundamental insights into the rational design of durable, outstanding aqueous zinc ion batteries.