镍锰氧化物的制备及其电化学性能的研究

发布时间：2018-04-14 20:23

本文选题：NiO + 多孔微球　；参考：《山东大学》2015年硕士论文

【摘要】：超级电容器作为一种新型的储能元件,结合了静电容器和化学电池的特点,拥有功率密度大、循环性能好、对环境无污染等优点,广泛应用于能量回收、电容汽车、仪器仪表等领域,是一种很有应用前景的技术。镍和锰等过渡金属氧化物由于价格低廉、电容性好,将取代Ru02等贵金属氧化物,是非常重要的超级电容器电极材料。众所周知,电极材料是储能元件的核心,而材料的物相组成和微观结构决定着材料的物理化学性能,因此,制备比表面积大和多孔的特殊形貌材料以及利用复合掺杂制备复合材料是超级电容器领域的研究热点。本文首先采用水热法制备出多孔球状NiO,探究其结构形成过程及机理；通过调节反应物浓度,制备出纳米薄片及微粒状NiO;通过对各种形貌样品的性能能对比分析,探索出具有最佳电化学性能的样品组分。其次,采用共沉淀法制备出镍锰复合氧化物物,通过调节反应物中Ni2+和MR2+的含量来获得不同的Ni/Mn比的复合氧化物,对其电化学性能进行对比分析。利用XRD来鉴定样品物相组成；利用SEM来观察其微观形貌结构；将样品粉末制作成电极,利用三电极系统来测试其电化学性能(GCD、CV、EIS)。研究表明：通过水热法可以制备出直径为5μm左右的多孔球状立方相NiO。对球体的形成过程进行研究发现,球体的构建需要从一个一维到多维,从部分到完整的渐变过程。反应物的浓度对样品的形貌有着重要影响。一系列的实验发现,球体形成最佳的反应物浓度组分是(CH2)6N4和NiSO4·6H2O分别为0.4M和0.2M,此时形成的球体最为完整,直径最为均匀。进一步调节反应物的浓度,可以得到另两种特殊形貌：纳米薄片和纳米颗粒。对这三种形貌样品的性能进行对比分析发现,多孔微球的电化学性能最为优良,在1A/g的电流密度下,比电容可达到1080 F/g,且有良好的可逆性和倍率性能。这是因为三维多孔球体拥有的更大的比表面积和合理的孔径分布,为电解液的渗入和离子的传递提供更为便利的通道,电荷转移阻力小,活性点多,电容性能好。利用共沉淀法可以制备出镍锰氧化物的复合物,反应物中Ni/Mn的比例对产物的物相组分和形貌都有重要影响。当反应物中只有Ni或只有Mn时,生成的样品分别为NiO纳米颗粒和Mn203微球。当Ni和Mn同时存在时,分为Ni/Mn1和Ni/Mn1两种情况。当Ni/Mn1时所得样品的主要物相是NiO,形貌为纳米级颗粒。随着Ni/Mn的降低,NiO衍射峰的强度降低。其中,当Ni/Mn降至3/1和2/1时,出现Mn2O3相,此时的样品为NiO和Mn2O3复合形成的镍锰复合氧化物。当Ni/Mn=1时,NiO消失,出现了NiMn2O4和NiMnO3两种单相,这是Mn进入到NiO的晶格中部分取代了Ni的位置形成的,此时样品的形貌也由纳米颗粒变为直径为1um左右的微球。当Ni/Mn1时生成的样品主要物相为Mn2O3,Ni以Ni2O3的形式存在,形成NiO和Mn2O3的复合物,形貌为微米级的微球。对镍锰复合氧化物进行电化学性能测试表明,电极的电容机制是法拉第赝电容机制,而由于不同Ni/Mn比所得样品的物相和形貌不同,对应的电化学性能不同。其中含有NiO/Mn2O3和Mn2O3共存的镍锰双氧化物复合物的组分(3/1、2/1、1/2)明显比单一的氧化物组分样品的CV曲线响应电流强度和所围面积大,所对应与EIS曲线高频曲线半径代表的电荷转移电阻小,电化学性能好。说明了镍锰氧化物的复合存在复合效应,提高了材料的利用率,优化了氧化物的电化学性能。
[Abstract]:Supercapacitor is a new energy storage device, combined with the characteristics of electrostatic containers and chemical batteries, has high power density and good cycle performance, no pollution to the environment, widely used in energy recovery capacitor, automotive, instrumentation and other fields, is a promising technique for nickel and. Manganese and other transition metal oxides due to its low cost, good capacitance, will replace the Ru02 noble metal oxide, is super capacitor electrode material is very important. As everyone knows, the electrode material is the core of the storage element, and the phase composition and microstructure determines the physical and chemical properties of materials, therefore, the preparation of more than the special morphology of material with large surface area and porous and composite doped composite material is a hot research topic in the field of super capacitor use. This paper firstly prepared by hydrothermal method and porous spherical NiO, explore its structure formation Process and mechanism; by adjusting the concentration of reactants, prepared nano flakes and particulate NiO; through the performance of various morphologies of samples can contrast analysis, explore a sample group has the best electrochemical performance. Secondly, the prepared nickel manganese oxide material by coprecipitation, the contents of Ni2+ and MR2+ of the reactants in order to achieve different Ni/Mn ratio of the composite oxides were analyzed on the electrochemical performance of samples. To identify the phase composition by XRD; to observe the morphology structure by SEM; the sample powder electrode to test its electrochemical performance by three electrode system (GCD, CV, EIS). The results show that by hydrothermal method can prepare porous spherical cubic diameter is about 5 m the study found that the forming process of NiO. sphere, the sphere of the need to build from a multi-dimensional, from part to complete The gradient process has an important impact on the morphology of the reactant concentration samples. Found a series of experiments, the sphere forming reactant concentration best components is (CH2) 6N4 and NiSO4 6H2O were 0.4M and 0.2M, the formation of the sphere of the most complete, the most uniform diameter. Further concentration of the reactants the other two can be obtained with special morphology: nano flakes and nanoparticles. Comparison analysis found that the performance of the three kinds of morphologies of samples, the electrochemical properties of porous microspheres is most excellent, the current density of 1A/g, the specific capacitance can reach 1080 F/g, and the reversibility and good rate capability. This is because the three-dimensional porous sphere has larger specific surface area and pore size distribution is reasonable, the electrolyte permeation and ion transfer to provide a more convenient channel, the charge transfer resistance is small, active points, good capacitance performance. Using the co precipitation method Can be prepared by composite nickel manganese oxide, Ni/Mn reaction in proportion to the product of the phase composition and morphology have important effects. When the reaction was only Ni or only Mn, the generated samples were NiO nanoparticles and Mn203 microspheres. When Ni and Mn exist at the same time, divided into Ni/ Mn1 and Ni/Mn1 two. The main thing when Ni/Mn1 of the sample is NiO, morphology of nano particles. With the decrease of Ni/Mn, reduce the NiO diffraction peak intensity. Among them, when Ni/Mn to 3/1 and 2/1, Mn2O3, Ni Mn composite oxide samples at NiO and Mn2O3 composite form. When Ni/Mn=1, NiO disappeared, there was NiMn2O4 and NiMnO3 two kinds of single phase, which is part of Mn into the NiO lattice form replaced the position of Ni, while the morphology of the samples from the nanoparticles into the diameter of about 1um microspheres. When the sample Ni/Mn1 is mainly generated Phase Mn2O3, Ni exists in the form of Ni2O3, NiO and Mn2O3 complex formation, morphology of micron microspheres. Electrochemical performance of nickel manganese oxides show that the capacitance mechanism of electrode is Faraday pseudocapacitive mechanism, but because of the different Ni/Mn ratio of the sample phase and morphology, electrochemical properties of the corresponding different. Which contains nickel manganese NiO/Mn2O3 coexistence of Mn2O3 and double oxide composites component (3/1,2/1,1/2) CV curve is more obvious than group of single sample oxide in response to the current intensity and the area enclosed by large, high frequency curve radius corresponding representative charge transfer resistance and EIS curve of small, good electrochemical performance. The compound exists the effect of composite nickel manganese oxide, improves the utilization rate of materials, optimization of the electrochemical properties of oxides.

【学位授予单位】：山东大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：O646.54;TM53

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