Liu Xiaolin, Jin Yucheng, Wang Hailong, Yang Xiya, Zhang Pianpian, Wang Kang, Jiang Jianzhuang
Beijing Advanced Innovation Center for Materials Genome Engineering, Beijing Key Laboratory for Science and Application of Functional Molecular and Crystalline Materials, Department of Chemistry and Chemical Engineering, School of Chemistry and Biological Engineering, University of Science and Technology Beijing, Beijing, 100083, China.
Adv Mater. 2022 Sep;34(37):e2203605. doi: 10.1002/adma.202203605. Epub 2022 Aug 15.
The poor electronic and ionic conductivities of covalent organic frameworks (COFs) severely restrict the development of COF-based electrodes for practical rechargeable batteries, therefore inspiring more research interest from the direction of both material synthesis and technology. Herein, a dual-porous COF, USTB-6, with good crystallinity and rich redox-active sites is conceived and fabricated by the polymerization of 2,3,8,9,14,15-hexa(4-formylphenyl)diquinoxalino [2,3-a:2',3'-c]phenazine and 2,7-diaminopyrene-4,5,9,10-tetraone. In particular, the heterogeneous polymerization of the same starting materials in the presence of graphene affords uniformly dispersed COF nanosheets with a thickness of 8.3 nm on a conductive carbon substrate, effectively enhancing the electronic conductivity of the COF-based electrode. Such a graphene-supported USTB-6 nanosheets cathode when used in a lithium-ion battery exhibits a specific capacity of 285 mA h g at a current density of 0.2 C and excellent rate performance with a prominent capacity of 188 mA h g at 10 C. More importantly, a capacity of 170 mA h g is retained by using the USTB-6 nanosheets cathode after 6000 cycles charge and discharge measurement at 5 C.
共价有机框架材料（COFs）较差的电子和离子传导性严重限制了基于COF的实用可充电电池电极的发展，因此激发了材料合成和技术方向更多的研究兴趣。在此，通过2,3,8,9,14,15-六（4-甲酰基苯基）二喹喔啉并[2,3-a:2',3'-c]吩嗪与2,7-二氨基芘-4,5,9,10-四酮的聚合反应，设计并制备了一种具有良好结晶度和丰富氧化还原活性位点的双孔COF，即USTB-6。特别地，相同起始原料在石墨烯存在下的非均相聚合反应，在导电碳基底上提供了厚度为8.3nm且均匀分散的COF纳米片，有效提高了基于COF的电极的电子传导性。这种石墨烯负载的USTB-6纳米片阴极在锂离子电池中使用时，在0.2C的电流密度下表现出285mA h g的比容量，并且具有优异的倍率性能，在10C时具有188mA h g的显著容量。更重要的是，使用USTB-6纳米片阴极在5C下进行6000次充放电测量后，仍保留170mA h g的容量。
