A functionalized separator enables dendrite-free Zn anode via metal-polydopamine coordination chemistry

Designing a multifunctional separator with abundant ion migration paths is crucial for tuning the ion transport in rocking-chair-type batteries. Herein, a polydopamine-functionalized PVDF (PVDF@PDA) nanofibrous membrane is designed to serve as a separator for aqueous zinc-ion batteries (AZIBs). The functional groups (-OH and -NH-) in PDA facilitate the formation of Zn-O and Zn-N coordination bonds with Zn ions, homogenizing the Zn-ion flux and thus enabling dendrite-free Zn deposition. Moreover, the PVDF@PDA separator effectively inhibits the shuttling of V-species through the formation of V-O coordination bonds. As a result, the Zn/NH4V4O10 battery with the PVDF@PDA separator exhibits enhanced cycling stability (92.3% after 1000 cycles at 5 A g(-1)) and rate capability compared to that using a glass fiber separator. This work provides a new avenue to design functionalized separators for high-performance AZIBs.