三种过渡金属复合氧化物的制备及其超电容行为研究

发布时间：2018-01-31 17:55

本文关键词： 三氧化二铋钼酸镍钨酸镍复合氧化物电极材料溶剂热电化学性能超级电容器比电容循环稳定性　出处：《西北师范大学》2014年硕士论文　论文类型：学位论文

【摘要】：超级电容器是一种集合了传统电容器高功率密度和电池高能量密度等优点的新型储能装置。因此，其应用广泛，，已成为新型化学电源研究中的热点之一。电极是超级电容器的重要组成元件，而电极材料又是构筑电极的重要组成部分。因此，现阶段有关超级电容器的研究主要集中在电极材料方面，开发具有优良电化学性能的电极材料对于超级电容器的发展至关重要。本文的研究工作中，我们注重复合材料能够相互彰显复合组分的性能这一优点，以获得良好电化学性能的目标材料为目的，进行了实验研究和探讨。本论文综述了超级电容器及超级电容器电极材料的种类、应用、当前研究热点，利用不同的合成方法制备了钴-铋复合氧化物、水合钼酸镍纳米花、钨酸镍纳米片等超级电容器材料。采用X-射线衍射(XRD)、傅里叶变换红外(FT-IR)光谱、场发射扫描电镜(FE-SEM)，透射电子显微镜(TEM)，对其所制样品的成分、形貌和结构进行了表征。并且采用循环伏安，恒流充放电技术对其电化学性能进行了相关的测试。主要内容概括如下： 1.利用钴和铋的硝酸盐，先采用溶剂热法制备得到钴-铋氢氧化物前驱体，然后通过后续热处理得到钴-铋复合氧化物。经分析，复合氧化物的最佳配比为Bi1.6Co0.2O2.6。该复合氧化物作为电极材料在-1.0~0.6V的电位窗口下工作，当比电流为1Ag-1时比电容可达838F g-1。因此，钴-铋复合氧化物作为超级电容器电极材料，具有潜在的应用价值。 2.利用回流法及后续热处理过程合成出了具有分级结构的纳米花状NiMoO4·xH2O电极材料。研究结果表明，样品的基元结构是纳米棒，这些纳米棒经自组装形成“松花”状的纳米花。NiMoO4·xH2O的含水量依热处理温度的升高而减小，但后续热处理不改变初始产物的晶型。当热处理温度为250°C时，该电极材料具有最优异的电化学性能：在电流密度为1Ag-1时，比电容为798Fg-1；在电流密度为7A g-1时,其比电容与1A g-1时的比电容相比，保持率高达71.8%；经过2000次循环后，复合物的比电容衰减小于20%。 3.利用简单的油浴法以及后续热处理过程合成了具有片状结构的纳米NiWO4电极材料。NiWO4-80为无定形结构，为了提高其结晶度，将其在600°C煅烧1h得到NiWO4-600晶体。在电流密度为1A g-1时，比电容为502F g-1；在电流密度为10Ag-1时,其比电容与1Ag-1时的比电容相比，保持率高达68.9%；经过4000次循环后，复合物的比电容仍然能保持初始值的81%。由此可见，该复合材料性能好、成本低且环境友好，是一种有潜在应用价值的超级电容器电极材料。
[Abstract]:Supercapacitor is a new type of energy storage device which combines the advantages of high power density of conventional capacitor and high energy density of battery, so it is widely used. Electrode is an important component of supercapacitor, and electrode material is an important part of building electrode. At present, the research on supercapacitors is mainly focused on electrode materials. The development of electrode materials with excellent electrochemical performance is very important for the development of supercapacitors. We pay attention to the advantage that the composite material can show the properties of the composite components mutually. We have carried on the experimental research and the discussion in order to obtain the target material with good electrochemical performance. In this paper, the types and applications of electrode materials for supercapacitors and supercapacitors are reviewed. The current research focus is focused on the preparation of cobalt-bismuth composite oxides and nickel molybdate hydrated nano-flowers by different synthetic methods. Supercapacitor materials, such as nickel tungstate nanocrystals, were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and field emission scanning electron microscopy (FE-SEM). The composition, morphology and structure of the samples were characterized by TEM and cyclic voltammetry. The electrochemical performance was tested by constant current charge-discharge technique. The main contents are summarized as follows: 1. Co-bismuth hydroxide precursor was prepared by solvothermal method using nitrate of cobalt and bismuth, and then cobalt-bismuth composite oxide was obtained by heat treatment. The optimum ratio of the composite oxides is Bi1.6Co0.2O2.6. the composite oxide acts as an electrode material under a potential window of -1.0V. When the specific current is 1Ag-1, the specific capacitance can reach 838F g-1.Therefore, cobalt-bismuth composite oxide as electrode material of supercapacitor has potential application value. 2. Nanoscale NiMoO4 路xH2O electrode materials with hierarchical structure were synthesized by reflux method and heat treatment. The results show that the structure of the sample is nanorods. The water content of these nanorods self-assembled to form "pine flower" nanorods. NiMoO4 路xH2O decreased with the increase of heat treatment temperature. However, the subsequent heat treatment does not change the crystal shape of the initial product. When the heat treatment temperature is 250 掳C, the electrode material has the best electrochemical performance: when the current density is 1Ag-1. The specific capacitance is 798Fg-1; When the current density is 7A g ~ (-1), the retention rate of the specific capacitance is 71.8% compared with the specific capacitance of 1A g ~ (-1). After 2000 cycles, the specific capacitance attenuation of the complex is less than 20. 3. Nanocrystalline NiWO4 electrode with sheet structure. NiWO4-80 was synthesized by simple oil bath method and heat treatment in order to improve its crystallinity. The NiWO4-600 crystal was calcined at 600 掳C for 1 h, and the specific capacitance was 502F g-1 when the current density was 1A g ~ (-1). When the current density is 10Ag-1, the retention rate of the specific capacitance is 68.9% compared with the specific capacitance of 1Ag-1. After 4000 cycles, the specific capacitance of the composite can still keep 81% of the initial value. It can be seen that the composite has good properties, low cost and environmentally friendly. Is a potential application of supercapacitor electrode material.
【学位授予单位】：西北师范大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM53

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