Covalent Organic Framework with Multiple Redox Active Sites for High-Performance Aqueous Calcium Ion Batteries

作者：Siqi Zhang, You‐Liang Zhu, Siyuan Ren, Chunguang Li, Xiaobo Chen, Zhenjiang Li, Yu Han, Zhan Shi, Shouhua Feng · 发表于：Journal of the American Chemical Society · 年份：2023 · DOI：10.1021/jacs.3c04657 · 被引用次数：141 · 研究领域：Advanced battery technologies research、Covalent Organic Framework Applications、Advancements in Battery Materials

Organic materials are promising for cation storage in calcium ion batteries (CIBs). However, the high solubility of organic materials in an electrolyte and low electronic conductivity remain the key challenges for high-performance CIBs. Herein, a nitrogen-rich covalent organic framework with multiple carbonyls (TB-COF) is designed as an aqueous anode to address those obstacles. TB-COF demonstrates a high reversible capacity of 253 mAh g –1 at 1.0 A g –1 and long cycle life (0.01% capacity decay per cycle at 5 A g –1 after 3000 cycles). The redox mechanism of Ca 2+ /H + co-intercalated in COF and chelating with C═O and C═N active sites is validated. In addition, a novel C═C active site was identified for Ca 2+ ion storage. Both computational and empirical results reveal that per TB-COF repetitive unit, up to nine Ca 2+ ions are stored after three staggered intercalation steps, involving three distinct Ca 2+ ion storage sites. Finally, the evolution process of radical intermediates further elucidates the C═C reaction mechanism.