结构可控的中空金属有机骨架微球的合成及在能源储存中的应用

发布时间：2018-04-10 00:08

  本文选题：金属有机骨架材料　切入点：锂离子电池　出处：《中国科学技术大学》2016年硕士论文

【摘要】：随着现代交通运输工具如混合动力电动汽车、全电动汽车等的发展,人们急切需要高能量密度和高功率密度电能存储装置(EES)来满足这些运输工具的需求。作为新兴EES系统的前列,锂离子、锂硫电池,超级电容器备受关注,但它们都很难同时满足较高的能量密度和功率密度、较高的倍率性能、较长的循环寿命、较高的安全性等所有要求。因此,开发具有新的化学特性及较高的电化学性能的电极材料并将其用于电能存储装置,具有很大的现实意义。金属有机骨架(MOFs)作为一类多孔结晶材料,通过较强的配位作用将无机、有机单元连接起来,大多数的无机单元是金属离子或金属氧化物,可充当电化学过程中的氧化还原活性位点,而有机配体是很好的碳源,因而MOFs作为电极材料有很大的潜力,尤其最近几年,MOFs在电化学能量储存领域中的应用日渐兴起并备受关注。在本论文中,我们基于乳液界面聚合,设计制备一种结构可控的金属有机骨架ZIF-8中空微球,并在此基础上进行以下三方面的应用研究。一、基于实验室前期工作,批量制备壳层厚度递增的三种结构的ZIF-8中空微球,并对其结构与性能进行详细研究；同时,通过负载Pd纳米粒子,用于选择性催化烯烃的加氢反应,结果显示,最薄壳层的ZIF-8(T)中空微球具有较高的效率和尺寸选择性。二、通过高温碳化金属有机骨架ZIF-8中空微球,获得具有较薄壳层、较高含量氮掺杂及较高比表面积的结构可控的多级孔纳米中空碳球,可以用于锂离子电池负极。经800℃煅烧所得的薄壳层中空纳米碳球将高掺氮(16.61%)、高比表面积(1038 m2g-1)、多层次的孔径分布(微、介孔)及可控结构等优点相结合,显示非常优异的电化学性能。在较低的电流密度100 mA g-1充放电100圈,可逆比容量高达2047 mAh g-1,保留了第二圈放电比容量的97%,循环稳定性非常好；甚至在较高的电流密度5 A g-1循环1000圈,可逆比容量也高达879 mAh g-1,显示卓越的倍率性能。同时,我们详细分析了碳化温度和碳球的结构对LIBs电化学性能的影响,进一步丰富金属有机骨架材料在锂离子电池负极中的应用。三、尝试研究碳化金属有机骨架所得的碳球在锂硫电池和超级电容器中的应用,结果显示,与同类碳材料相比,其电化学性能较差,有待进一步改善和研究。
[Abstract]:With the development of modern transportation tools such as hybrid electric vehicles (HEVs) and all-electric vehicles (EVs), high energy density and high power density electric energy storage devices are urgently needed to meet the needs of these vehicles.As the forefront of the emerging EES system, lithium ion, lithium-sulfur batteries and supercapacitors have attracted much attention, but they are difficult to satisfy both high energy density and power density, high rate performance, and long cycle life.Higher safety requirements, etc.Therefore, it is of great practical significance to develop electrode materials with new chemical characteristics and high electrochemical performance and to use them in electric energy storage devices.As a kind of porous crystalline materials, organometal-organic frameworks (MOFs) connect inorganic and organic units through strong coordination. Most of the inorganic units are metal ions or metal oxides.It can act as redox active site in electrochemical process, and organic ligand is a good carbon source, so MOFs has great potential as electrode material.Especially in recent years, MOFs have been widely used in electrochemical energy storage.In this thesis, we designed and prepared a kind of organometallic skeleton ZIF-8 hollow microspheres based on emulsion interfacial polymerization.Firstly, three kinds of ZIF-8 hollow microspheres with increasing shell thickness were prepared in batches, and their structure and properties were studied in detail based on the previous work in laboratory. At the same time, they were used to selectively catalyze the hydrogenation of olefins by loading PD nanoparticles.The results show that the thinnest shell ZIF-8T hollow microspheres have high efficiency and size selectivity.Secondly, ZIF-8 hollow microspheres with thin shell layer, high nitrogen content doping and high specific surface area were obtained by carbonized metal-organic skeleton hollow microspheres at high temperature, which can be used as negative electrode of lithium ion battery.The hollow hollow carbon spheres calcined at 800 鈩，

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