Interfacial Solvothermal Synthesis of Redox‐Active Piperazine‐Linked Covalent Organic Frameworks for Zinc‐Ion Storage

Conjugated covalent organic frameworks (COFs) with abundant redox‐active sites have been novel electrode materials for advanced aqueous zinc‐ion batteries. However, the number of COFs featured with multiple redox sites and extensive conjugated system is limited. Herein, a novel piperazine‐linked phthalocyanine‐based COF with dense redox‐active sites (named as CoPc‐NH‐TABQ‐iAA) is synthesized by the interfacial solvothermal method, in which the monomers of hexadecafluoro‐phthalocyanine cobalt (II) (CoPcF 16 ) and 1,2,4,5‐tetramino‐benzoquinone (TABQ) with poor solubility in the reaction solvent (1,4‐dioxane) not only enable an interfacial reaction system, resulting in inclined AA stacking configurations, but also provide dense C–F and C=O electroactive centers for zinc‐ion storage. The prepared CoPc‐NH‐TABQ‐iAA exhibits high crystallinity, high chemical stability, and a narrow bandgap. Benefiting from these excellent physical and chemical properties, CoPc‐NH‐TABQ‐iAA delivers an outstanding specific capacity and stable cycle life under an ultrahigh current (62.5 mA h g −1 at 10 A g −1 , with a capacity retention rate of 72.4% after 1000 cycles). Density functional theory calculations demonstrate the multielectron transfer mechanism with each repeating unit storing 8 Zn 2+ by C–F and C=O redox sites. This investigation provides an insight for the rational design of COF‐based electrode materials through molecular engineering.