Regulating the radical intermediates by conjugated units in covalent organic frameworks for optimized lithium ion storage  

作　　者：Shuai Gu Xiaoxia Ma Jingjing Chen Rui Hao Zhiqiang Wang Ning Qin Wei Zheng Qingmeng Gan Wen Luo Muqing Li Zhiqiang Li Kemeng Liao Hao Guo Guiyu Liu Kaili Zhang Zhouguang Lu 

机构地区：[1]Department of Materials Science and Engineering,Shenzhen Key Laboratory of Interfacial Science and Engineering of Materials,Guangdong-Hong Kong-Macao Joint Laboratory for Photonic-Thermal-Electrical Energy Materials and Devices,Southern University of Science and Technology,Shenzhen 518055,Guangdong,China [2]Department of Mechanical Engineering,City University of Hong Kong,Kowloon,Hong Kong 999077,China

出　　处：《Journal of Energy Chemistry》2022年第6期428-433,I0012,共7页能源化学（英文版）

基　　金：supports from the Basic Research Project of the Science and Technology Innovation Commission of Shenzhen (No. JCYJ20200109141640095);the Shenzhen Key Laboratory of Interfacial Science and Engineering of Materials (No. ZDSYS20200421111401738);the Leading Talents of Guangdong Province Program (No. 2016LJ06C536);the GuangdongHong Kong-Macao Joint Laboratory (No. 2019B121205001);the National Natural Science Foundation of China (No. 21875097);the support from the Hong Kong Research Grants Council (Project number CityU 11218420)。

摘　　要：Organic active units often transform into radical intermediates during the redox processes but exhibit poor cycling stability due to the uncontrollable redox of the radicals. Herein, we report a facile and efficient strategy to modulate the molecular orbital energies, charge transport capacities, and spin electron densities of the active units in covalent organic frameworks(COFs) via regulating the conjugated unit size to optimize the redox activity and stability of the organic radicals. COFs based on different imide conjugated units exhibit tunable discharge voltages, rate performance and cycling stabilities. Detailed characterizations and theoretical calculation reveal that imide radicals are the important active intermediates during the redox processes of these COFs. Specifically, increasing the size of the imide conjugated units could effectively delocalize the radical electrons and improve the stability of the COFs electrodes. This study offers a very effective strategy to modulate the redox chemistry of organic materials for electrochemical energy storage.

关 键 词：Organic electrodes Radical intermediates Covalent organic frameworks 

分 类 号：TM912[电气工程—电力电子与电力传动] O641.1[理学—物理化学]