Advancements in Separator Materials for Aqueous Zinc Batteries

Abstract

Aqueous zinc batteries (AZBs) are becoming promising candidates for grid-scale energy storage because of their inherent safety, cost-effectiveness, and high theoretical capacity. However, their widespread application is hindered by critical challenges, including zinc (Zn) dendrite formation, hydrogen evolution reaction (HER), corrosion, and cathode material dissolution. The separator plays a crucial role in regulating ion transport, suppressing side reactions, and promoting uniform Zn deposition. While recent advancements in separator design have introduced various modification strategies to enhance electrochemical performance, a systematic classification based on the modification location remains lacking. This review comprehensively analyzes recent advancements in AZB separators, categorized by modification position—anode side, cathode side, and whole-separator modifications. Key modification strategies, including ion-selective layers, interfacial engineering, and composite functional membranes, are discussed in detail, with an emphasis on their effects on Zn2+ flux regulation, dendrite suppression, and long-term cycling stability. Additionally, emerging separator materials such as covalent organic frameworks (COFs), metal-organic frameworks (MOFs), and inorganic-organic hybrid separators are highlighted for their potential to optimize battery performance. This review provides theoretical insights and design principles for developing next-generation AZB separators by elucidating the underlying mechanisms governing separator modifications. Finally, we discuss future research directions, focusing on separator thinness, enhanced ion selectivity, interface stability, corrosion resistance, and scalable manufacturing to accelerate the commercialization of high-performance AZBs.