Anodic Metal–Organic Frameworks Enabling Functional Ionic Distributor Sustains Stable Aqueous Zinc Metal Anodes

Aqueous zinc-ion batteries (AZIBs) have attracted much attention due to their high safety, low cost, and high capacity. One critical issue for restricting the development of AZIBs is the formation of zinc dendrites, causing insufficient cyclic stability and safety concerns. Regulating ionic transport to optimize the distribution of Zn2+ ions and inhibit the migration of anions is one feasible route. As an indispensable part, the separators could be ideal candidates for acting as a functional ionic distributor (FID) promoting the transport of Zn2+ ions. Herein, FID was designed via coating anodic metal-organic frameworks (MOFs) on commercial glass fiber separators (GF). Attributing to the existence of abundant anodic nanochannels, a high Zn2+ ions transference number (0.79) was realized. Besides, the double electrode layer accelerated the transport of Zn2+ ions, leading to a high ionic conductivity (34.48 mS cm-1). Thus, Zn symmetric cells with FID achieved the cyclic stability of 300 and 130 h on 1 mA cm-2 and 0.5 mAh cm-2 as well as 5 and 2.5 mAh cm-2, superior to that of GF. Further, theoretical simulation demonstrated the suppressed transport of SO4 2- in MOFs. This study could offer an attainable strategy for constructing stable AZIBs based on functional separators.