Synergistic Manipulation of Hydrogen Evolution and Zinc Ion Flux in Metal‐Covalent Organic Frameworks for Dendrite‐free Zn‐based Aqueous Batteries

Abstract Zn‐based aqueous batteries have attracted much attention because of their high theoretical‐capacity, safety, and low‐cost, yet the H 2 ‐evolution, qualification or inhibition mechanism investigations that are closely related to the dendrite‐growth are rare and challenging. Herein, a series of zincophilic metal‐covalent organic frameworks (e.g., Zn‐AAn‐COF, Zn‐DAAQ‐COF, and Zn‐DAA‐COF) have been explored as model‐platforms to manipulate the H 2 ‐evolution and Zn 2+ flux. Best of them, Zn‐AAn‐COF based cell only produces 0.002 mmol h −1 cm −2 H 2 , which is >2 orders of magnitude lower than bare Zn. Noteworthy, it affords high stability for 3000 cycles (overpotential, <79.1 mV) at 20 mA cm −2 in symmetric‐cell and enhanced cycling‐stability up to 6000 cycles at 2000 mA g −1 in the assembled full‐battery. Besides, mechanistic characterizations show that Zn‐AAn‐COF can enhance the energy‐barrier of H 2 ‐evolution and homogenize the ion‐distribution or electric‐filed to achieve high performance.