Covalent Organic Frameworks Coupled with Redox Center and Adsorption Site for Efficient Shuttle‐Free Zn‐Iodine Batteries
Jingdong Feng, Wang‐Kang Han, Jun-Jun He, Yong Liu, Ruo‐Meng Zhu, Jinfang Zhang, Huan Pang, Zhi‐Guo Gu
Abstract
Abstract Aqueous zinc‐iodine (Zn‐I 2 ) batteries exhibit significant potential for next‐generation energy storage system, but the polyiodide shuttle effect severely impairs their performance and stability. Herein, a series of woven covalent organic frameworks (COFs), namely COF‐RuNCS‐X (X = 1–6), with pre‐designed ruthenium(II) redox center and sulfur adsorption sites were constructed for shuttle‐free cathode material in Zn‐I 2 batteries. The porous COF‐RuNCS‐X with abundant sulfur adsorption sites showed a selective adsorption of I 3 − species for effectively mitigating the shuttle effect. Meanwhile, the incorporation of ruthenium(II) center into the COFs skeleton enhanced the redox kinetics of iodine species. Remarkably, COF‐RuNCS‐6 featuring the large pore size and high degree of conjugation demonstrated a discharge specific capacity as high as 395.8 mAh g −1 in Zn‐I 2 batteries and exhibited cycle stability up to 5000 cycles. This work provides a new understanding of the design of COF‐based materials as efficient shuttle‐free cathode materials for Zn‐I 2 batteries.