Extensive research on anodes with higher capacity than carbon-based materials is driven by the great demand for lithium-ion batteries with higher energy density. However, the cycling stability of high-capacity anodes is usually hindered by significant volumetric changes and structural collapse during the cycling process. Metal-organic frameworks (MOFs) are an emerging class of crystalline materials, and their derivatives are expected as alternative high-capacity anodes, resulting from the merits of easy functionalization and pore engineering. In this study, a novel porous Co-MOF-derived composite anode was prepared by the pyrolysis of a nonporous Co-cyclooctatetrathiophene tetrapyridine (Co-COTTTP) template. X-ray absorption spectroscopy and high-resolution transmission electron microscopy revealed that the precise composition of Co-COTTTP-derived composite anodes with exposed rich redox cobalt oxides active sites, appropriate degree of graphitization, and N, S-doping, which effectively enhanced the electrochemical performance of the composite anodes. Thus, the resulting porous MOF-derived composite anode demonstrated high specific capacity and long cycling stability in the assembled batteries. Specifically, the cells assembled with Co-COTTTP-500 anodes delivered a high reversible specific capacity of 1005.7 mAh/g after 100 cycles at 0.1 A/g and can be cycled steady for 800 cycles at 1 A/g, indicating the structure stability during cell operation. In summary, this study provides a feasible strategy to prepare high-performance MOF-derived anodes and deep understanding for the structure–activity relationship, contributing to the fabrication of high-energy–density lithium-ion batteries.

中文翻译：

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基于环八氢四噻吩的 MOF 衍生多孔材料作为锂离子电池的高性能负极


对具有更高能量密度的锂离子电池的巨大需求推动了对比碳基材料容量更高的负极的广泛研究。然而，高容量阳极的循环稳定性通常会受到循环过程中显着的体积变化和结构崩溃的阻碍。金属有机框架 （MOF） 是一类新兴的晶体材料，其衍生物有望成为替代的高容量阳极，这得益于易于功能化和孔隙工程的优点。在本研究中，通过热解无孔 Co-cyclooctatetrathiphhene tetrapyridine （Co-COTTTP） 模板制备了一种新型多孔 Co-MOF 衍生的复合阳极。X 射线吸收光谱和高分辨率透射电子显微镜显示，Co-COTTTP 衍生的复合阳极具有暴露的富含氧化还原钴氧化物活性位点、适当的石墨化程度和 N、S 掺杂，有效增强了复合阳极的电化学性能。因此，所得的多孔 MOF 衍生的复合负极在组装电池中表现出高比容量和长循环稳定性。具体来说，用 Co-COTTTP-500 负极组装的电池在 0.1 A/g 下循环 100 次后，可提供 1005.7 mAh/g 的高可逆比容量，并且可以在 1 A/g 下稳定循环 800 次，表明电池运行期间的结构稳定性。综上所述，本研究为制备高性能 MOF 衍生负极和深入了解构效关系提供了一种可行的策略，有助于制造高能量密度锂离子电池。