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 Ca2+/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 Ca2+ ion storage. Both computational and empirical results reveal that per TB-COF repetitive unit, up to nine Ca2+ ions are stored after three staggered intercalation steps, involving three distinct Ca2+ ion storage sites. Finally, the evolution process of radical intermediates further elucidates the C═C reaction mechanism.
Bibliographical noteKAUST Repository Item: Exported on 2023-08-04
Acknowledgements: This work was financially supported by the Foundation of Science and Technology Development of Jilin Province, China (20200801004GH), the National Natural Science Foundation of China (21621001), 111 Project (B17020), and Major Basic Research Program of Natural Science Foundation of Shandong Province (ZR2020ZD09).
ASJC Scopus subject areas
- Colloid and Surface Chemistry