Yang Su Hyun, Park Seung-Keun, Kang Yun Chan
Department of Materials Science and Engineering, Korea University, Anam-Dong, Seongbuk-Gu, Seoul, 136-713, Republic of Korea.
Department of Chemical Engineering, Kongju National University, 1223-24 Cheonan-daero, Seobuk-gu, Cheonan, 31080, Republic of Korea.
Nanomicro Lett. 2020 Oct 27;13(1):9. doi: 10.1007/s40820-020-00539-6.
In this work, a novel vacuum-assisted strategy is proposed to homogenously form Metal-organic frameworks within hollow mesoporous carbon nanospheres (HMCSs) via a solid-state reaction. The method is applied to synthesize an ultrafine CoSe nanocrystal@N-doped carbon matrix confined within HMCSs (denoted as CoSe@NC/HMCS) for use as advanced anodes in high-performance potassium-ion batteries (KIBs). The approach involves a solvent-free thermal treatment to form a Co-based zeolitic imidazolate framework (ZIF-67) within the HMCS templates under vacuum conditions and the subsequent selenization. Thermal treatment under vacuum facilitates the infiltration of the cobalt precursor and organic linker into the HMCS and simultaneously transforms them into stable ZIF-67 particles without any solvents. During the subsequent selenization process, the "dual confinement system", composed of both the N-doped carbon matrix derived from the organic linker and the small-sized pores of HMCS, can effectively suppress the overgrowth of CoSe nanocrystals. Thus, the resulting uniquely structured composite exhibits a stable cycling performance (442 mAh g at 0.1 A g after 120 cycles) and excellent rate capability (263 mAh g at 2.0 A g) as the anode material for KIBs.
在这项工作中，提出了一种新颖的真空辅助策略，通过固态反应在中空介孔碳纳米球（HMCSs）内均匀形成金属有机框架。该方法用于合成一种超细的CoSe纳米晶体@N掺杂碳基质，其被限制在HMCSs内（表示为CoSe@NC/HMCS），用作高性能钾离子电池（KIBs）的先进阳极。该方法包括在真空条件下进行无溶剂热处理，以在HMCS模板内形成基于钴的沸石咪唑酯框架（ZIF-67），以及随后的硒化。真空下的热处理有助于钴前驱体和有机连接体渗透到HMCS中，并同时将它们转化为稳定的ZIF-67颗粒，无需任何溶剂。在随后的硒化过程中，由有机连接体衍生的N掺杂碳基质和HMCS的小尺寸孔组成的“双限制系统”可以有效抑制CoSe纳米晶体的过度生长。因此，所得的具有独特结构的复合材料作为KIBs的阳极材料表现出稳定的循环性能（120次循环后在0.1 A g下为442 mAh g）和优异的倍率性能（在2.0 A g下为263 mAh g）。
