Liu Yuan-Yuan, Li Xiang-Chun, Wang Shi, Cheng Tao, Yang Huiyan, Liu Chen, Gong Yanting, Lai Wen-Yong, Huang Wei
Key Laboratory for Organic Electronics and Information Displays & Institute of Advanced Materials (IAM), Nanjing University of Posts & Telecommunications, 9 Wenyuan Road, 210023, Nanjing, China.
Frontiers Science Center for Flexible Electronics (FSCFE), MIIT Key Laboratory of Flexible Electronics (KLoFE), Northwestern Polytechnical University, West Youyi Road, 710072, Xi'an, China.
Nat Commun. 2020 Nov 3;11(1):5561. doi: 10.1038/s41467-020-18844-4.
Covalent organic frameworks (COFs) have served as a family of porous crystalline molecules for various promising applications. However, controllable synthesis of COFs with uniform morphology is paramount yet still remains quite challenging. Herein, we report self-templated synthesis of uniform and unique hollow spheres based on highly conjugated three-dimensional (3D) COFs with diameters of 500-700 nm. A detailed time-dependent study reveals the continuous transformation from initial nano sphere-like particles into uniform hollow spherical structures with Ostwald ripening mechanism. Particularly, the resulting 3D COF (3D-Sp-COF) is prone to transport ions more efficiently and the lithium-ion transference number (t) of 3D-Sp-COF reaches 0.7, which even overwhelms most typical PEO-based polymer electrolytes. Inspiringly, the hollow spherical structures show enhanced capacitance performance with a specific capacitance of 251 F g at 0.5 A g, which compares favorably with the vast majority of two-dimensional COFs and other porous electrode materials.
共价有机框架（COFs）作为一类多孔晶体分子，具有各种有前景的应用。然而，可控合成具有均匀形态的COFs至关重要，但仍然极具挑战性。在此，我们报道了基于直径为500 - 700纳米的高度共轭三维（3D）COFs的均匀且独特的中空球体的自模板合成。一项详细的时间依赖性研究揭示了从初始的纳米球状颗粒通过奥斯特瓦尔德熟化机制连续转变为均匀中空球形结构的过程。特别地，所得的3D COF（3D-Sp-COF）更易于高效传输离子，其锂离子迁移数（t）达到0.7，甚至超过了大多数典型的基于聚环氧乙烷的聚合物电解质。令人鼓舞的是，中空球形结构表现出增强的电容性能，在0.5 A g下比电容为251 F g，与绝大多数二维COFs和其他多孔电极材料相比具有优势。
