金属氧化物纳米复合阵列的制备及其储能应用研究

发布时间：2018-05-18 12:49

本文选题：过渡金属氧化物 + 纳米阵列　；参考：《华中师范大学》2017年博士论文

【摘要】：随着现代社会对能源需求的增加,人们对大容量高功率储能设备的要求也越来越高。纳米材料由于其具有的小尺寸效应,量子尺寸效应,表面效应和宏观量子隧道效应而受到人们的广泛研究,并在现代社会的各个领域得到大量的应用,同时也被视为下一代储能器件的关键性技术。在各种纳米材料中,纳米阵列材料,由于其相比于其它纳米结构有着更为优异的性能而受到研究工作人员的广泛关注,并被视为未来能源技术领域的重要研究方向。纳米阵列材料所具有的特性有:(1)能提供直接的电子传输通道,提高电极材料的导电性;(2)减少离子在活性物质中的扩散距离,增强材料的倍率性能;(3)极大的比表面积,增加电极材料与电解液的接触面,减少充放电时间;(4)更稳固的结构,能承受更大的体积膨胀和机械降解;(5)直接生长在集流体上,能省去导电添加剂和粘结剂的使用;(6)其较为松散的结构和形貌较易于构建更多种类的复合材料,并在不同材料之间产生协同效应;(7)相比于粉体材料,纳米阵列材料有着更稳固的结构,因而会对环境产生的影响更小,而且更加安全。同时纳米阵列材料还存在许多的缺陷,严重的制约了其在储能器件方面的大规模应用。相比于其它纳米材料,纳米阵列材料的制备过程相对更加复杂,制备成本更加高昂,不利于大规模生产;而且阵列材料在一维尺度上受到限制,使得阵列材料只能作为薄膜材料使用。在本论文中,我们通过探索不同阵列材料的生长过程,着力于克服其在制备与一维尺度上的困难与限制,以及通过特殊的方法将那些不能生长出纳米线阵列的材料制备成纳米线阵列的形貌。此外我们同时还进一步的研究如何提高电极材料的性能,是得其能够进一步的被大规模实际应用。本文的主要研究工作有以下几个方面:1、利用水热法,我们首先在碳布基底上得到了生长均匀的MnO2纳米片薄膜。同时针对MnO2材料性能的不足与缺陷,设计了新型的MnO2/PPy复合纳米薄膜材料。通过对其导电性的改善而提高了其电化学稳定性与倍率性能,通过对MnO2纳米材料在不同条件的电解质下所装配的电容器进行阻抗分析,我们得到了实验性能最好的H3PO4/PVA凝胶电解质。该电解质不仅对氧化锰的性能有一定的帮助,同时还使得MnO2/PPy复合材料的实际应用更有优势。得益于电极材料的优越性能与电解质的稳定,该准固态超级电容器的最高能量密度可以达到2.04 μWh cm-2,同时其最高功率密度可以达到0.432mWcm-2,表现出了优异的电容性能。该电容器同时在0.8 V高电压的条件下稳定循环1000次之后,仍能保持93.2%的初始容量,进一步证明了MnO2/PPy复合纳米薄膜材料有着极其稳定的电化学性能。2、我们通过对ZnO生长机理的研究,利用晶体成核与生长的特性,成功的掌握了 ZnO纳米线阵列可控生长的方法,并能得到几十微米长的超长ZnO纳米线阵列。然后通过进一步实验,我们成功的在ZnO纳米线阵列的表面装载了大量的MnO2活性物质。通过研究MnO2生长的条件以及随后样品的电化学性能,我们成功的筛选并得到了有着超高面积比容量的ZnO/MnO2复合纳米线阵列材料,极大的提高了 MnO2材料在超级电容器方面的实用性。通过进一步的电化学测试,我们证实了该材料优异的电化学性能。该电极材料有着最大112mF cm-2的超高容量,并有着较为优异的电化学稳定性,在1000次循环后仍然能保持81mF cm-2容量。远高于一般薄膜电极的超高容量,使其更具有商业应用的价值。3、通过巧妙的设计,我们利用简单的水热法及电沉积法制备合成了 Ti02-Mo03核壳纳米线阵列电极材料。TiO2-MoO3核壳纳米线阵列由于其独特的形貌,其各个材料之间的协同效应有:(1)Ti02材料在锂电池充放电过程中(即使是在高倍率电流密度下)表现出优异的结构稳定性,其体积膨胀在反应过程中几乎没有,因而作为支柱材料可以极大的提升MoO3材料整体的循环稳定性和倍率性能;(2)MoO3纳米壳层材料,能提供相对较大的容量和较高的电导性;(3)阵列结构设计能简化电极材料的制备过程,以及提供活性材料与集流体之间直接的电子传输渠道;(4)三维电极结构的设计极大的提高电极材料在单位面积上负载的活性物质质量。当Ti02与MoO3的质量比为1:1时,TiO2-MoO3核壳纳米线阵列的质量比容量能达到670 mA g-1,循环稳定性能达到200次以上,以及其面积比容量能达到3.986 mAh cm-2,其性能能比的上一般的商用锂离子电池。同时我们还利用TiO2-Mo03核壳纳米线阵列负极材料与LiCoO2薄膜正极材料相搭配组装了全电池设备,该电池的最大能量密度可以达到285 Whkg1,同时其最大的功率密度可以达到1086W kg-1,其优异的性能具有较大的实用性,同时其复合模式也能应用在其它的纳米材料上。
[Abstract]:With the increasing demand for energy in modern society, the demand for large capacity and high power energy storage equipment is becoming higher and higher. Nanomaterials have been widely studied by people because of their small size effect, quantum size effect, surface effect and macroscopic quantum tunneling effect, and have been widely used in various fields of modern society. At the same time, it is considered as a key technology for the next generation of energy storage devices. In all kinds of nanomaterials, nanoarray materials have been widely concerned by researchers because of their superior performance compared to other nanostructures, and are regarded as an important research direction in the field of energy technology in the future. There are: (1) can provide direct electronic transmission channels to improve the conductivity of electrode materials; (2) reduce the diffusion distance of ions in the active material, enhance the ratio of the material; (3) maximum specific surface area, increase the contact surface of the electrode material and electrolyte, reduce charge and discharge time; (4) a more stable structure, can withstand a larger volume expansion. And mechanical degradation; (5) direct growth on the collection of fluids can save the use of conductive additives and adhesives; (6) its looser structure and morphology are easier to build more kinds of composite materials and produce synergistic effects between different materials; (7) the nano array material has a more stable structure than the powder material, and therefore the ring will be on the ring. The impact of the environment is smaller and safer. At the same time, there are many defects in nanoscale array materials, which seriously restrict its large-scale application in energy storage devices. Compared to other nanomaterials, the preparation process of nanomaterials is more complex, the cost of preparation is higher, and it is not conducive to mass production; and the array material is not good. The material is limited on one dimensional scale so that the array material can only be used as a film material. In this paper, by exploring the growth process of different array materials, we focus on overcoming the difficulties and limitations on the preparation and one dimension, and the preparation of materials that can not be produced by a rice wire array through a special method. In addition, we have further studied how to improve the performance of electrode materials, and it is necessary to further be applied in large scale. The main research work of this paper is as follows: 1, using the hydrothermal method, we first obtained the uniform MnO2 nanoscale film on the carbon substrate. In view of the defects and defects of the properties of MnO2 materials, a new type of MnO2/PPy composite nano thin film material was designed. By improving its conductivity, the electrochemical stability and multiplex performance were improved. Through the impedance analysis of the capacitor assembled under different conditions of the electrolyte of MnO2 nanomaterials, we got the best experimental performance. H3PO4/PVA gel electrolyte. This electrolyte not only helps the performance of manganese oxide, but also makes the application of the MnO2/PPy composite more advantageous. Thanks to the superior performance of the electrode material and the stability of the electrolyte, the maximum energy density of the quasi solid supercapacitor can reach 2.04 mu Wh cm-2, and the highest energy density of the supercapacitor can be reached at the same time. The power density can reach 0.432mWcm-2, showing excellent capacitive performance. The capacitor can still maintain the initial capacity of 93.2% after a stable cycle of 1000 times under the condition of 0.8 V high voltage. It is further proved that the MnO2/PPy composite nanomaterials have extremely stable electrochemical performance.2. We pass on the mechanism of ZnO growth. The study, using the characteristics of crystal nucleation and growth, successfully grasped the method of controlled growth of ZnO nanowire arrays, and obtained a long ZnO nanowire array of dozens of microns. Then, through further experiments, we successfully loaded a large number of MnO2 active substances on the surface of the ZnO nanowire array. The conditions for the growth of MnO2 were studied. As well as the electrochemical performance of the subsequent samples, we successfully screened and obtained the ZnO/MnO2 composite nanowire array with super high area specific capacity, which greatly improved the practicability of the MnO2 material in supercapacitor. By further electrochemical testing, we confirmed the excellent electrochemical performance of the material. The material has the super high capacity of the maximum 112mF cm-2, and has excellent electrochemical stability. After 1000 cycles, it can still maintain the capacity of 81mF cm-2. It is far higher than the super high capacity of the ordinary film electrode, making it more valuable in commercial application. By ingenious design, we make use of simple hydrothermal method and electrodeposition method to prepare it. Ti02-Mo03 nuclear shell nanowire array electrode material.TiO2-MoO3 nuclear shell nanowire array, due to its unique morphology, the synergistic effect of various materials: (1) Ti02 material exhibits excellent structural stability during charge discharge process of lithium batteries (even at high rate current density), and its volume expansion is almost not in the reaction process. Therefore, as a pillar material, it can greatly improve the cyclic stability and multiplying performance of the MoO3 material as a whole; (2) the MoO3 nanoscale material can provide relatively large capacity and higher conductivity; (3) the array structure design can simplify the preparation of the electrode material and provide the direct electronic transmission channel between the active material and the fluid collector. (4) the design of the three-dimensional electrode structure greatly improves the quality of the active material loaded on the surface of the electrode material. When the mass ratio of Ti02 to MoO3 is 1:1, the mass specific capacity of the TiO2-MoO3 nuclear shell nanowire array can reach 670 mA g-1, the cyclic stability performance is up to 200 times, and the area specific capacity can reach 3.986 mAh cm-2, The performance can be compared with the ordinary commercial lithium ion batteries. At the same time, we also use the TiO2-Mo03 nuclear shell nanowire array negative electrode and the LiCoO2 film positive material to assemble the full battery equipment. The maximum energy density of the battery can reach 285 Whkg1, and the maximum power density can reach 1086W kg-1. It has great practicability and its compound mode can also be applied to other nano materials.
【学位授予单位】：华中师范大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：TB383.1

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