Recent advances in functionalized separators for aqueous zinc ion batteries

As an emerging energy storage device, aqueous zinc ion batteries (AZIBs) stand out among many metal ion batteries due to their high energy density, low cost, and high safety. However, the inevitable issues of dendrite growth, hydrogen evolution reaction (HER), and passivation layer generation reduce the stability of zinc anodes and become the bottleneck for the development of AZIBs. The separator ensures the safe operation of batteries as an important component. To overcome the intrinsic problems of widely used glass fiber (GF) separators, the strategy of designing functionalized films has received extensive attention as an effective method to improve the electrochemical performance of aqueous zinc ion batteries. Herein, the review systematically summarizes the latest advances of functionalized separators in AZIBs, mainly focusing on the design strategies and mechanistic investigation of raw and modified separator materials. In the end, the current challenge and future prospects of the functionalized separators for zinc ion batteries are presented.