Liu Xiaolin, Ding Xu, Zheng Tianyu, Jin Yucheng, Wang Hailong, Yang Xiya, Yu Baoqiu, 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.
Chongqing Key Laboratory of Green Synthesis and Applications, College of Chemistry, Chongqing Normal University, Chongqing 401331, China.
ACS Appl Mater Interfaces. 2024 Jan 31;16(4):4741-4750. doi: 10.1021/acsami.3c16319. Epub 2024 Jan 19.
Covalent organic frameworks (COFs) are notable for their remarkable structure, function designability, and tailorability, as well as stability, and the introduction of "open metal sites" ensures the efficient binding of small molecules and activation of substrates for heterogeneous catalysis and energy storage. Herein, we use the postsynthetic metal sites to catalyze polysulfide conversion and to boost the binding affinity to active matter for lithium-sulfur batteries (LSBs). A dual-pore COF, USTB-27, with topology has been successfully assembled from the imine chemical reaction between 2,3,8,9,14,15-hexa(4-formylphenyl)diquinoxalino [2,3-:2',3'-c]phenazine and [2,2'-bipyridine]-5,5'-diamine. The chelating nitrogen sites of both modules are able to postsynthetically functionalize with single cobalt sites to generate USTB-27-Co. The discharge capacity of the sulfur-loaded S@USTB-27-Co composite in a LSB is 1063, 945, 836, 765, 696, and 644 mA h g at current densities of 0.1, 0.2, 0.5, 1.0, 2.0, and 5.0 C, respectively, much superior to that of non-cobalt-functionalized species S@USTB-27. Following the increased current densities, the rate performance of S@USTB-27-Co is much better than that of S@USTB-27. In particular, the capacity retention at 5.0 C has a magnificent increase from 19% for the latter species to 61% for the former one. Moreover, S@USTB-27-Co exhibits a higher specific capacity of 543 mA h g than that of S@USTB-27 (402 mA h g) at a current density of 1.0 C after electrochemical cycling for 500 runs. This work illustrates the "open metal sites" strategy to engineer the active chemical component conversion in COF channels as well as their binding strength for specific applications.
共价有机框架（COFs）以其卓越的结构、功能可设计性、可定制性以及稳定性而著称，引入“开放金属位点”可确保小分子的有效结合以及用于多相催化和能量存储的底物活化。在此，我们利用合成后金属位点催化多硫化物转化，并增强锂硫电池（LSBs）对活性物质的结合亲和力。一种具有拓扑结构的双孔COF，USTB - 27，已通过2,3,8,9,14,15 - 六（4 - 甲酰基苯基）二喹喔啉并[2,3 - :2',3'-c]吩嗪与[2,2'-联吡啶]-5,5'-二胺之间的亚胺化学反应成功组装而成。两个模块的螯合氮位点能够通过单钴位点进行合成后功能化，生成USTB - 27 - Co。在锂硫电池中，负载硫的S@USTB - 27 - Co复合材料在电流密度分别为0.1、0.2、0.5、1.0、2.0和5.0 C时的放电容量分别为1063、945、836、765、696和644 mA h g，远优于未进行钴功能化的S@USTB - 27。随着电流密度增加，S@USTB - 27 - Co的倍率性能远优于S@USTB - 27。特别是，在5.0 C时的容量保持率从后者的19%大幅提高到前者的61%。此外，在1.0 C电流密度下经过500次电化学循环后，S@USTB - 27 - Co的比容量为543 mA h g，高于S@USTB - 27（402 mA h g）。这项工作展示了“开放金属位点”策略，用于设计COF通道中的活性化学成分转化及其在特定应用中的结合强度。
