Supramolecular Engineering of Cathode Materials for Aqueous Zinc‐ion Energy Storage Devices: Novel Benzothiadiazole Functionalized Two‐Dimensional Olefin‐Linked COFs

Abstract

AbstractTwo‐dimensional covalent organic frameworks (COFs) have emerged as promising materials for energy storage applications exhibiting enhanced electrochemical performance. While most of the reported organic cathode materials for zinc‐ion batteries use carbonyl groups as electrochemically‐active sites, their high hydrophilicity in aqueous electrolytes represents a critical drawback. Herein, we report a novel and structurally robust olefin‐linked COF‐TMT‐BT synthesized via the aldol condensation between 2,4,6‐trimethyl‐1,3,5‐triazine (TMT) and 4,4′‐(benzothiadiazole‐4,7‐diyl)dibenzaldehyde (BT), where benzothiadiazole units are explored as novel electrochemically‐active groups. Our COF‐TMT‐BT exhibits an outstanding Zn2+storage capability, delivering a state‐of‐the‐art capacity of 283.5 mAh g−1at 0.1 A g−1. Computational and experimental analyses reveal that the charge‐storage mechanism in COF‐TMT‐BT electrodes is based on the supramolecularly engineered and reversible Zn2+coordination by the benzothiadiazole units.