The Role and Mechanism of Separators in Aqueous Zinc Metal Batteries: a Critical Review

Abstract Aqueous zinc metal batteries (AZMBs) have gained increasing attention in recent years as a promising energy storage system due to their high specific capacity, low cost, and eco‐friendliness. However, dendrite growth and side reactions of zinc anodes severely hinder their reversibility and sustainability. The separator, an indispensable component of battery devices, increasingly influences the overall performance of AZMBs, although research into separators for AZMBs is still in its infancy. Despite years of exploration and development, a clear and systematic understanding of the underlying mechanisms of various separators is still lacking in the field. Herein, this article reviews the research advances and development status of separator modification strategies for AZMBs, with a focus on their key roles and mechanisms. In principle, these mechanisms encompass electric field distribution, ion sieve effect, crystal orientation, and desolvation effect. The unique advantages and limitations of each mechanism in regulating zinc deposition are comprehensively discussed. Notably, this review also provides an analysis of the effectiveness evaluation of separators in AZMBs. Finally, the critical challenges and future trends of separator modification for AZMBs are discussed, with the aim of inspiring the development of high‐performance separators and advancing the progress of AZMBs.