Highly\nReversible and Stable Zinc Anode Enabled by\na Fully Conjugated Porous Organic Polymer Protective Layer

Abstract

Zn\nanodes are advantageous for use in rechargeable aqueous zinc\nion batteries (ZIBs) because of their high theoretical specific capacities,\nlow redox potentials, and safety. However, Zn anodes have several\nchallenges, such as easy corrosion and uncontrollable zinc dendrite\ngrowth, which deteriorate the long-term cycling capability and, thus,\nbadly hinder the practical applications of ZIBs. This study demonstrates\na highly reversible and stable Zn anode by constructing a positive\nfully conjugated porous organic polymer-based (TM–OH) multifunctional\nprotective layer. This TM–OH-based layer can provide a stable\nand corrosion-resistant “wall” with fine electrolyte\nwettability simultaneously, which is due to the fully conjugated structure\nand abundant hydrophilic OH. Moreover, Zn deposits of TM–OH@Zn\ndisplay horizontally rather than upright dendrite, which is probably\nattributed to interaction between triazine rings rich of lone pair\nelectrons and Zn²⁺. Consequently, the TM–OH@Zn electrode\nshows ultralow voltage hysteresis (25, 28 mV at 0.1, 1 mA cm^–2 in a symmetric cell, respectively), highly reversible stripping/plating\nbehavior, and excellent cycling stability (good operation even after\n1200 h at 0.1 mA cm^–2, 0.05 mAh cm^–2 in a symmetric cell). TM–OH@Zn//MnO₂ ZIBs were\nfabricated and exhibited better comprehensive electrochemical performance\nthan Zn//MnO₂ ZIBs, demonstrating the potential practical\napplication of TM–OH@Zn.