肼还原氧化石墨烯及α相镍钴氢氧化物材料的电化学性能研究

发布时间：2019-01-10 21:48

【摘要】：近年来,超级电容器(又称电化学电容器)因其大功率和长循环寿命的优异特性而引起了国内外学者广泛的研究兴趣,在大功率电器、电动车和各种便携式电子设备等领域具有广阔的应用前景。而新型超级电容器取决于高性能电极材料的研究。在各种活性电极储能材料中,二维片状石墨烯结构材料和片层镍钴基氢氧化物材料,因为特殊的层状结构和优良的电化学性能,已逐渐地被应用于超级电容器电极活性材料的研究中。本文以上述两种材料为研究对象,分别研究了各自材料的制备方法、形貌结构和电化学性能,并讨论了了活性材料结构与其电化学性能之间的机理关系。本文主要研究结果如下:采用改进的Hummers法制备出二维片状氧化石墨烯(GO),并通过水热肼还原法获得还原氧化石墨烯(rGO)。实验通过XRD、Raman光谱和FT-IR傅立叶红外变换技术分析了rGO表面结构特点,发现rGO表面存在大量含氧基团和结构缺陷,且研究了还原肼的加入量对其表面无序度的影响。在电化学性能分析中,GO和rGO都表现出典型碳材料的双电层电容性能,rGO活性材料具有比GO更好的电化学性能,且还原肼的加入量对其电化学性能有较大影响,当实验中还原肼的加入量为0.6 mL时,rGO在1 Ag-1的电流密度下获得207 Fg-1的高比电容。采用一种简单易行的前驱体转化法,成功地制备了组分不同而形貌结构相近的α相双金属镍钴氢氧化物材料。这种材料具有独特的薄片状结构和良好的氧化还原活性。并且相比于氢氧化镍材料,钴离子的引入对活性材料的循环稳定性、比容量和倍率性能的提高都有很大帮助。在1 Ag-1的电流密度下,镍钴组分比为1:1的Ni0.5Co0.5氢氧化物表现出1600 Fg-1的高比容量,并且在10 Ag-1的大电流密度下经过1000次循环后还能保持为初始比电容100%的容量。进一步通过傅立叶红外变换技术分析了层间乙二醇分子的存在与镍钴氢氧化物循环稳定性的关系,提出了钴离子的引入使得乙二醇分子能在镍钴氢氧化物层间稳定存在,而层间乙二醇分子的存在抑制了α相镍钴氢氧化物向β相的转变,从而使活性材料获得更高的循环稳定性。
[Abstract]:In recent years, supercapacitors (also called electrochemical capacitors) have attracted a wide range of research interests at home and abroad because of their excellent characteristics of high power and long cycle life. Electric vehicles and various portable electronic devices and other fields have a broad application prospects. New supercapacitors depend on the research of high performance electrode materials. Among all kinds of active electrode energy storage materials, two-dimensional flake graphene structure material and lamellar nickel cobalt based hydroxide material, due to their special layered structure and excellent electrochemical properties, It has been gradually applied to the study of electrode active materials for supercapacitors. In this paper, the preparation methods, morphology and electrochemical properties of the two kinds of materials were studied, and the relationship between the structure of the active materials and their electrochemical properties was discussed. The main results of this paper are as follows: the two-dimensional flake graphene oxide (GO), was prepared by modified Hummers method and reduced graphene oxide (rGO). Was obtained by hydrothermal hydrazine reduction method. XRD,Raman spectra and FT-IR Fourier transform infrared transform (FTIR) techniques were used to analyze the surface structure of rGO. It was found that there were a large number of oxygen groups and structural defects on the surface of rGO. The influence of the amount of reductive hydrazine on the surface disorder was studied. In the electrochemical performance analysis, both GO and rGO showed the double layer capacitance performance of typical carbon materials. The electrochemical properties of rGO active materials were better than those of GO, and the amount of reductive hydrazine had great influence on their electrochemical performance. When the amount of reduced hydrazine was 0.6 mL, the rGO obtained a high specific capacitance of 207 Fg-1 at the current density of 1 Ag-1. The 伪 phase nickel cobalt hydroxide materials with different composition and similar morphology were successfully prepared by a simple and convenient precursor conversion method. This material has a unique lamellar structure and good redox activity. Compared with the nickel hydroxide material, the introduction of cobalt ion can greatly improve the cycling stability, specific capacity and performance of the active materials. At a current density of 1 Ag-1, Ni0.5Co0.5 hydroxides with a ratio of 1:1 to nickel and cobalt exhibit a high specific capacity of 1600 Fg-1. After 1000 cycles at a high current density of 10 Ag-1, the capacity can be kept to 100% of the initial specific capacitance. The relationship between the existence of interlaminar ethylene glycol and the cyclic stability of nickel-cobalt hydroxide is analyzed by Fourier transform infrared transform technique. It is proposed that the introduction of cobalt ion can stabilize the existence of ethylene glycol in the nickel-cobalt hydroxide layer. However, the existence of interlaminar ethylene glycol inhibits the transition from 伪 phase nickel cobalt hydroxide to 尾 phase, which makes the active material obtain higher cycle stability.
【学位授予单位】：华中科技大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：O611.4;TM53

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