阵列复合材料制备、结构与锂离子电池性能研究

发布时间：2018-04-24 21:53

本文选题：化学浴沉积 + 电沉积　；参考：《哈尔滨理工大学》2017年硕士论文

【摘要】：能量转化器件已成为当今各国关注的重要技术研究方向之一,在能量转化器件的使用过程中存在电化学能量储存和转换。其中,电极材料是能量转化器件的重要组成部分,直接影响能量转化器件的能量存储性能。因此,近年的各项研究主要集中在探索新的电极材料和改善现有的电极材料等方面。本文利用化学浴沉积、电沉积等方法在泡沫镍基底上制备出Co_3O_4、Co_3O_4/PANI(聚苯胺)纳米棒阵列。利用XRD、SEM和Raman等多种测试手段对阵列结构分析表明:Co_3O_4纳米棒阵列的表面成功地被一层10-20nm的导电聚苯胺涂层覆盖。该电极在无需粘合剂的情况下,测试其电化学性能及锂电池的循环与倍率性能。对比两种电极材料电化学性能得出,Co_3O_4/PANI核壳结构纳米棒阵列电极在300 mA g-1的电流密度、50个循环后容量仍然保持78%,而纯Co_3O_4纳米棒阵列电极50个循环后容量仅为57%。在电流密度为3000 mA g-1下,Co_3O_4/PANI纳米棒阵列电极的容量仍保留有45%的容量,高于Co_3O_4纳米棒阵列电极12%的保留容量。分析原因主要为:(1)Co_3O_4/PANI阵列结构在其纳米棒结构之间具有足够的空间储存锂离子,大比表面积的纳米棒结构增大了电解液与纳米棒的接触面积,缩短了锂离子的传输路径;(2)聚苯胺良好的导电性和稳定性可保护Co_3O_4纳米棒阵列在循环过程中的体积膨胀,并增加复合电极的电荷转移速率,进而提高复合电极的容量和循环稳定性。为进一步探索排列一致的阵列电极,利用化学浴沉积、电沉积和水热的方法制备空心镍微米棒/碳纳米球核壳阵列结构电极。该阵列电极在100个循环周期后仍保持148 mAh g-1的容量,仍保留有86.8%的容量,具有良好的循环性能,在50mA g-1的电流密度下该阵列电极的充电容量高达170 mAh g-1。分析得出,(1)镍微米棒之间存在的较大空隙有利于碳纳米球与电解质的接触,空隙结构可以承受嵌锂/脱锂的过程的体积膨胀和收缩,(2)纳米碳球填充在镍微米棒的空隙中,形成良好的导电网络,提高了电极材料的导电性。这些优良的结构特性使电极材料具有较高的电化学储锂性能和较稳定的循环性能。
[Abstract]:Nowadays, energy conversion devices have become one of the most important research directions in the world. Electrochemical energy storage and conversion exist in the use of energy conversion devices. Among them, electrode material is an important part of energy conversion devices, which directly affects the energy storage performance of energy conversion devices. Therefore, recent studies have focused on exploring new electrode materials and improving existing electrode materials. In this paper, Cos _ 3O _ S _ 4 / Co _ 3O _ T _ 4 / pan _ (4) nanorods arrays were prepared on nickel foam substrate by means of chemical bath deposition and electrodeposition. The analysis of the structure of the array by XRD-SEM and Raman shows that the surface of the nanorod array is successfully coated with a conductive Polyaniline coating of 10-20nm. The electrochemical performance of the electrode and the cycle and rate performance of the lithium battery were measured without binder. Compared with the electrochemical properties of the two electrode materials, the current density of CoSZ / pani core / shell nanorod array electrode at 300mAg ~ (-1) is obtained. The capacity of 50 nanorod array electrodes is still 78m after 50 cycles, while that of pure Co_3O_4 nanorod array electrode is only 57g after 50 cycles. At the current density of 3000 Ma g ~ (-1), the capacity of Co3OO _ 4 / pani nanorod array electrode is still 45%, which is higher than that of Co_3O_4 nanorod array electrode (12%). The main reason is that there is enough space between the nanorods to store lithium ions, and the nanorod structure with large specific surface area increases the contact area between electrolyte and nanorods. The good conductivity and stability of Polyaniline can protect the volume expansion of Co_3O_4 nanorods during cycling and increase the charge transfer rate of the composite electrode. Thus, the capacity and cycle stability of the composite electrode are improved. In order to further explore the coherent array electrodes, hollow nickel micron rod / carbon nanospheres array structure electrodes were prepared by chemical bath deposition, electrodeposition and hydrothermal methods. The array electrode has a capacity of 148 mAh g ~ (-1) and a capacity of 86.8% after 100 cycles. It has good cycling performance. The charging capacity of the array electrode is as high as 170 mAh g ~ (-1) at the current density of 50mA g ~ (-1). The results show that the large gap between nickel micron rods and carbon nanospheres is favorable to the contact between carbon nanospheres and electrolytes, and the pore structure can withstand the volume expansion and shrinkage of lithium intercalation / lithium removal process) carbon nanospheres are filled in the voids of nickel micron rods. A good conductive network is formed, and the conductivity of electrode material is improved. These excellent structural properties make the electrode materials have high electrochemical lithium storage performance and stable cycling performance.
【学位授予单位】：哈尔滨理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TM912

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