Thin and low‐cost separator enables dendrite growth suppression in zinc anodes for ultra‐stable aqueous zinc‐ion batteries

Abstract Aqueous zinc‐ion batteries (AZIBs) have garnered significant attention owing to their intrinsic safety and the abundance of zinc resources. Traditional separators, such as glass fiber (GF), face challenges such as zinc dendrite penetration, inadequate mechanical strength, and excessive thickness, which results in increased internal resistance and diminished battery performance. In this study, we investigate the use of a mixed cellulose ester (MCE) filter membrane as a separator for AZIBs. The 110‐μm‐thick MCE separator exhibits a mechanical strength of 4.88 MPa, which is 12 times greater than that of the 325‐μm‐thick GF separator, and effectively resists zinc dendrite formation, even with a thinner design. Zn symmetric batteries utilizing the MCE separator exhibit a cycle time of 2700 h at 1 mA cm −2 . The MCE separator, incorporating hydroxyl and nitrogen functional groups, promotes uniform zinc deposition and mitigates the formation of by‐products on the zinc anode, thereby enhancing corrosion resistance. Zn||MnO 2 full batteries with the MCE separator demonstrate a specific capacity of 161 mAh g −1 at 1 A g −1 , with a capacity retention of 80.1% after 500 cycles. Furthermore, Zn||VO 2 full cells employing the MCE separator exhibit excellent rate performance and cycling stability. At 0.25 A g −1 , the Zn||VO 2 cell retains 86.9% of its capacity after 800 cycles, demonstrating a high capacity of 243 mAh g −1 . This study offers novel insights into enhancing the performance of AZIBs through the selection of a low‐cost, high‐strength, and thin separator design.