Robust Zinc Anode Enabled by Sulfonate-Rich MOF-Modified Separator

Abstract

Aqueous zinc ion batteries (ZIBs) hold great promise for large-scale energy storage; however, severe zinc dendritic growth and side reactions on the anode dramatically impede their commercial application. Herein, a Zr-based MOF (UiO-66) functionalized with a high density of sulfonic acid (─SO3H) groups is used to modify the glass fiber (GF) separator of ZIBs, providing a unique solution for stabilizing Zn anode. Benefiting from the strong interaction between zincophilic −SO3H and Zn2+, this sulfonate-rich UiO-66 modified GF (GF@UiO-S2) separator not only guarantees the homogeneous distribution of ion flux, but also accelerates the ion migration kinetics. Hence, the GF@UiO-S2 separator promotes uniform Zn plating/stripping on the Zn anode and facilitates the desolvation of hydrated Zn2+ ions at the interface, which helps guide dendrite-free Zn deposition and inhibit undesired side reactions. Accordingly, the Zn||Zn symmetric cell with this separator achieves excellent cycling stability with a long cycle life exceeding 3450 h at 3 mA cm−2. Besides, the Zn||MnO2 full cell paired with this separator delivers remarkable cyclability with 90% capacity retention after 1200 cycles. This design of metal–organic frameworks functionalized separators provides a new insight for constructing highly robust ZIBs.