硫化铜及其复合物作锂离子电池电极材料的研究

发布时间：2018-02-15 15:05

本文关键词： CuS 还原的氧化石墨烯纳米复合物锂离子电池光催化　出处：《北京理工大学》2015年硕士论文　论文类型：学位论文

【摘要】：日益加剧的环境与能源危机激励着人们研究更加先进的能源存储与转化设备，而这些设备的性能的优劣很大程度上依赖于其材料。硫化铜由于独特的物理、化学性质而被广泛应用于能量存储与转化，例如锂离子电池、光催化、超级电容器等。本文在乙二醇与二甲基亚砜的混合溶液体系中，在未引入任何表面活性剂及模板的情况下成功制备出硫化铜纳米线束。研究发现在反应过程中的中间产物对最终产物的形貌起着决定性作用。通过XRD，Raman，SEM，TEM对制备的CuS纳米线束进行了结构和形貌的表征。合成的CuS纳米线束作为锂电池负极极材料表现出高的放电容量及优异的循环性能，其在0.1C循环80圈后容量依旧维持在540mA h g-1。这主要是由于一维纳米线有序结构提供了更多的反应活性位，缩短了电子传导的距离。在成功制备CuS纳米线束的基础上通过引入氧化石墨烯(GO)及控制反应参数，一锅法成功制备出CuS纳米线/还原的氧化石墨烯(CuSNWs/rGO)复合物。通过XRD，，Raman，FT-IR，SEM，TEM，XPS一系列表征，证明了在该体系中合成CuS纳米线的同时也将GO还原。得到的CuSNWs/rGO纳米复合物表现出卓越的储锂性能、优秀的循环性能以及倍率性能，尤其是大倍率性能。在4C循环500圈后容量依旧保持在320mA h g-1，并且在0.5C循环100圈容量保持在620mAh g-1。优良的电化学性能主要是由于：一方面纳米复合物能够调节在脱嵌锂过程中巨大的体积变化。另一方面rGO纳米片的存在具有优良的电子电导率能提供二维导电网状结构的同时吸附限制CuS转换过程中产生的多硫化锂溶解，从而提高电极的循环稳定性。此外，CuSNWs/rGO纳米复合物还表现出较好的催化性能。与单纯硫化铜纳米线相比，其紫外吸收光谱发生了红移，对光激发的活性变强。在光照下对亚甲基蓝降解30min后降解率达到94%，更重要的是该材料在无光条件下也表现出良好的催化性能。优秀的催化性能主要是由于一方面rGO纳米片的引入增加了表面积，对降解物的吸附量增多；另一方面石墨烯的引入提高了电子的传导，利于电子-空穴的分离，延长了电子空穴对的寿命，从而提高催化活性。
[Abstract]:The growing environmental and energy crisis has inspired the study of more advanced energy storage and conversion devices, the performance of which depends largely on their materials. Chemical properties are widely used in energy storage and conversion, such as lithium ion batteries, photocatalysis, supercapacitors and so on. In the mixed solution system of ethylene glycol and dimethyl sulfoxide, Copper sulfide nanowires were successfully prepared without introducing any surfactants and templates. It was found that the intermediate products played a decisive role in the morphology of the final product. The structure and morphology of the nanowires were characterized. The synthesized CuS nanowires showed high discharge capacity and excellent cycling performance as anode materials for lithium batteries. Its capacity remains at 540 Ma h g -1 after 80 cycles at 0.1 C. this is mainly due to the fact that the ordered structure of one-dimensional nanowire provides more reactive sites and shortens the distance of electron conduction. Based on the successful preparation of CuS nanowires, the CuS nanowires / reduced graphene oxide CuSNs / rGOS complexes were successfully prepared by introducing graphene oxide (GOO) and controlling reaction parameters. It is proved that the synthesized CuS nanowires are also reduced to go in this system. The obtained CuSNWs/rGO nanocomposites exhibit excellent lithium storage performance, excellent cycling performance and rate performance. In particular, the performance of large rate. After 4C cycle 500 cycles, the capacity remains at 320mA h g-1, and at 0.5C cycle 100 cycle capacity remains at 620mAh g-1.The excellent electrochemical performance is mainly due to: on the one hand, the nanocomposites can be adjusted in deintercalation. On the other hand, the existence of rGO nanocrystals has excellent electronic conductivity, which can provide two-dimensional conductive network structure while adsorbing to limit the dissolution of lithium polysulfide produced in the process of CuS conversion. In addition, CuSNWs / rGO nanocomposites showed good catalytic performance. Compared with pure copper sulfide nanowires, the UV absorption spectra of CuSNWs / rGO nanocomposites shifted red. The degradation rate of methylene blue reached 94% after 30 min degradation under light. More importantly, the material also showed good catalytic performance under the condition of no light. The excellent catalytic performance was mainly due to one side. The introduction of rGO nanoparticles increases the surface area, On the other hand, the introduction of graphene can improve the electron conduction, facilitate the separation of electron and hole, prolong the lifetime of electron hole pair, and improve the catalytic activity.
【学位授予单位】：北京理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TM912;TQ131.21

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