Recent Progress on Zn Anodes for Advanced Aqueous Zinc-Ion Batteries

Aqueous Zn-ion batteries (AZIBs) have attracted much attention due to their excellent safety, cost-effectiveness, and eco-friendliness thereby being considered as one of the most promising candidates for large-scale energy storage. Zn metal anodes with a high gravimetric/volumetric capacity are indispensable for advanced AZIBs. However, pristine Zn metal anodes encounter severe challenges in achieving adequate cycling stability, including dendrite growth, hydrogen evolution reaction, self-corrosion, and by-product formation. Because all these reactions are closely related to the electrolyte/Zn interface, the subtle interface engineering is important. Many strategies targeted to the interface engineering have been developed. In this review, a timely update on these strategies and perspectives are summarized, especially focusing on the controllable synthesis of Zn, Zn surface engineering, electrolyte formulation, and separator design. Furthermore, the corresponding internal principles of these strategies are clarified, which is helpful to help seek for new strategies. Finally, the challenges and perspectives for the future development of practical AZIBs are discussed, including the conducting of in advanced in situ testing, unification of battery models, some boundary issues, etc. This review is expected to guide the future development and provi beacon light direction for aqueous zinc ion batteries.