Multifunctional Separator Engineering: Unlocking the Potential of Aqueous Zinc‐Ion Batteries

Aqueous zinc‐ion batteries (AZIBs) have emerged as an idealcandidate for large‐scale energy storage due to their inherent safety and low cost. However, key challenges, including Zn dendrite formation, Zn anode corrosion/passivation, hydrogen evolution, and cathodic dissolution, significantly inhibit the development of high‐performance AZIBs with long‐term durability. Separators, as one of the important components in the AZIBs, show a critical impact on the electrochemical performance. Nevertheless, the systematic understanding of the underlying mechanism of separators improving the battery performance is still unclear. Here, this article focuses on the research progress of AZIBs separators, providing a systematic review of the core role of separators in AZIBs in mechanical integrity and their influence on the other critical components such as anodes, cathodes, and electrolytes. The engineering strategies for functional separators are then analyzed and categorized into matrix modification, functional grafting, organic coating, and inorganic stacking. Notably, this review summarizes recent advances of functional separators based on the substrates, followed by a discussion of the critical challenges and future directions of the research in functional separators for AZIBs, providing theoretical guidelines to advance the Zn battery technologies.