Amino-Enabled Desolvation Sieving Effect Realizes Dendrite-Inhibiting Thin Separator for Durable Aqueous Zinc-Ion Batteries

Abstract

The cyclability of aqueous zinc-ion batteries is greatly influenced by Zn dendrites and parasitic reactions. Although separator modifications have proven to be effective in addressing these issues, most of the developed separators are too thick to meet practical requirements. Herein, an amino (−NH2)-functionalized Zr-based metal–organic framework (MOF), i.e., UiO-66-NH2, is incorporated into lignocellulose separator. The amino functional groups not only possess good zincophilicity but also strongly interact with H2O molecules through hydrogen bonding. Therefore, the abundant intersecting subnano-sized channels within UiO-66-NH2 act as desolvation sieves and facilitate the migration and uniform distribution of Zn2+ ions. Even at a rather low thickness of 20 µm, the modified separator can significantly improve the reversibility of Zn electrochemistry and suppress water-induced hydrogen evolution. With the use of this separator, the Zn electrodes demonstrate a working life exceeding 2000 h at a current density of 2 mA cm−2 with remarkable dendrite-free characteristic and remain operationally viable under ultrahigh areal capacity of 25 mAh cm−2. Additionally, the resultant Zn//MnO2 battery provides superior rate capability and excellent cyclability. This study provides novel insights into the utilization of amino functional groups to inhibit unfavorable phenomena in aqueous batteries.