Directionally modulated zinc deposition by a robust zincophilic Cu-phthalocyanine protective layer in dendrite-free aqueous zinc ion batteries

Abstract

The directional modulation of zinc (Zn) deposition with further investigation of the dendrite-formation mechanism is vital in artificial anode protective layer for aqueous Zn-ion batteries (AZIBs). Herein, a robust metalated covalent organic framework (CuPc-COF) used as the artificial anode protective layer is proposed, in which the zincophilic sites of π-conjugated periodic skeletons are precisely designed to modulate the directional migration of Zn2+, the multiple redox-active sites facilitate the Zn2+ confinement and transfer, and the central metal copper (Cu) serves as the inhibitor to eliminate the hydrogen evolution side reactions. By combining theoretical calculations with experiments, the π-conjugated planar CuPc-COF layer is a desired protective coating of AZIB anodes with directionally transport channels and abundant redox active sites, thus inducing two-dimensional deposition of Zn. Attributed to these superiorities, the fabricated CuPc-COF@Zn anode demonstrates excellent cycling lifespan in both symmetrical cell (exceeding 2500 h at 1 mA cm−2) and full cell with different cathodes (more than 3000 cycles at 1 A g−1), outperforming most reported zinc anodes with COF-based layers.