新型过渡金属化合物液相制备及其电化学储能性能研究

发布时间：2018-02-17 07:05

本文关键词： 过渡金属氧族化合物液相制备电化学性能　出处：《内蒙古大学》2017年博士论文　论文类型：学位论文

【摘要】：特定组成结构的功能纳米材料在生物、能源、电子等领域具有广泛的应用,选择理想材料、控制其组成与结构、研究其形成机制一直是材料与化学领域重要的研究方向。过渡金属化合物具有较高理论容量,作为锂离子电池和超级电容器电极材料受到广泛的研究关注。本论文以过渡金属化合物为研究对象,利用液相合成的方法,可控制备了一系列新型结构纳米材料,研究了其微纳结构形成机制及其在超级电容器或锂离子电池中的应用性能。论文主要内容包括:1.采用水热合成和加热后处理的方法可控制备了介孔和花束结构的纳米钴酸镍材料,在材料结构表征和超级电容器性能测试基础上,探讨了材料结构和性能之间的构效关系,结果表明,与花束结构钴酸镍相比,介孔钴酸镍具有更优异的比电容量及稳定性,在放电电流密度为2,4,6,8和10A-1时,其比容量分别为1619,1 1114,780,648和571 Fg-1。6 Ag-1电流密度进行1000次循环充放电测试后其比容量保持率可达98%,说明有效的介孔结构是介孔钴酸镍高比电容量和良好稳定性的关键。2.利用极性溶剂掺杂的方法可控制备了海胆结构、花瓣结构、管结构、立方结构的NiCo_2S_4纳米材料。三电极测试体系对不同形貌NiCo_2S_4超级电容器性能测试结果表明:管状结构NiCo_2S_4具有最优异的电化学活性和储能效果,在电流密度为3,4,6,8和10 Ag-1时,比电容量分别为1048,868,750,620,525 Fg-1;在10 A g-1的电流密度下,5000次循环测试后可以保持75.9%初始容量。材料结构分析与机理探讨证明,管状结构NiCo_2S_4比表面积大,中空结构有利于电解液渗透,增加电极材料与电解液之间的接触面积,实现高电流密度下电子及离子的快速迁移,加快氧化还原反应速度,从而呈现出较高的超级电容器性能。3.以溶剂热法合成了空心海胆结构的镍、钴二元硫化物前驱体,离子交换反应得到NiCo_2S_4/Ni_xCo_(9-x)S_8二元硫化物,聚多巴胺包覆和高温碳化后得到N掺杂碳包覆的二元硫化物(Ni_xCo_(9-x)S_8@C)。三电极体系电化学性能测试表明:Ni_xCo_(9-x)S_8@C相对于NiCo_2S_4/Ni_xCo_(9-x)S_8具有更加优越的电容性能,其在电流密度为2 Ag-1,3Ag-1,4Ag-1,5 Ag-1,6Ag-1,8Ag-1 时,比电容分别为 1404,1200,1147,1138,1000 Fg-1及580 Fg-1,并且2000次循环充放电后,总容量基本保持不变,表现出良好的循环稳定性。优异的电化学性能证明N掺杂碳包覆和空心海胆结构的协同效应更有益于增加材料导电性、缩短电子与离子扩散路径,加快电极电化学反应,提高材料电化学活性和稳定性。4.以SiO_2微球为模板,水热法制备了尺寸分布均匀的MoS_2包覆的碳空心微球,以其为电极材料,研究了其电化学储能性能,结果发现:MoS_2包覆的碳空心微球在100 mA g-1的电流密度下循环100次后其锂电容量仍保持在750 mAh g-1;而在2 A g-1的电流密度下锂电容量可以达到349 mAh g-1。这些结果表明MoS_2包覆的碳空心微球在电化学储能方面比传统二维MoS_2纳米片具有更加突出的结构与性能优势。5.利用热注入的方法在油相体系中合成了尺寸约100nm的六边形SnSSe纳米片,通过二次生长在其表面实现了 Fe_2O_3沉积,得到Fe_2O_3/SnSSe复合材料。在材料组成、结构与形貌分析表征的基础上,分别将Fe_2O_3/SnSSe和SnSSe纳米片用作锂离子电池负极材料,结果发现,Fe_2O_3/SnSSe纳米片具有优越的锂电性能,可在电流密度100 mA g-1时保持919 mAh g-1的容量,且在200 mA g-"循环100次后容量仍保持755 mAh g-1。此外,这项工作为合成其他硫硒化合物及研究他们的锂电特性提供了新的思路。
[Abstract]:The energy function of nano materials in biological specific structure, and has wide application fields such as electronics, ideal material, control its composition and structure, study the formation mechanism has been an important research direction of materials and chemical fields. Transition metal compounds have high theoretical capacity, as a lithium ion battery and super capacitor electrode materials by extensive research attention. In this paper, transition metal compounds as the research object, using the method of liquid phase synthesis, controlled synthesis of a series of novel nanostructured materials, studied the micro nano structure and formation mechanism in super capacitor or lithium ion battery application performance. The main content of this thesis includes: 1. using the method hydrothermal synthesis and postprocessing of nano heating NiCo2O4 mesoporous material and structure of the bouquet preparation, test based on material characterization and properties of super capacitor And discussed the structure-activity relationship between the structure and properties of materials. The results showed that compared with the bouquet structure NiCo2O4, mesoporous cobalt nickel is more excellent than the electric capacity and stability, the discharge current density of 2,4,6,8 and 10A-1, the specific capacity were 1114780648 1619,1 and 571 Fg-1.6 Ag-1 current density 1000 cycles after the charge discharge tests than the capacity retention rate of 98%, indicating the mesoporous structure is the key to effective.2. mesoporous cobalt nickel high specific capacitance and good stability can be controlled by sea urchin structures through the method of polar solvent doping, petal structure, tube structure, NiCo_2S_4 nano materials with cubic structure. The three electrode test system show that the test results of different morphologies of NiCo_2S_4 super capacitor performance: NiCo_2S_4 tubular structure has excellent electrochemical activity and the effect of energy storage, when the current density is 3,4,6,8 and 10 Ag-1, than A capacitance of 1048868750620525 Fg-1 respectively; the current density of 10 A g-1, 5000 cycles after the test can keep 75.9% of the initial capacity. To investigate the proof analysis and mechanism of material structure, NiCo_2S_4 tubular structure with large specific surface area, the hollow structure facilitates the electrolyte permeability, increase the contact area between the electrode and electrolyte materials, to achieve rapid migration ion electron and high current density, accelerate the oxidation reduction reaction speed, thus showing a super capacitor high performance.3. by solvothermal synthesis of the hollow structure of the sea urchin nickel, cobalt two sulfide precursor, ion exchange reaction of NiCo_2S_4/Ni_xCo_ (9-x) S_8 two element sulfide, polydopamine coating and high temperature carbonization after the two yuan N sulfide doped carbon coated (Ni_xCo_ (9-x) S_8@C). The electrochemical properties of three electrode system testing showed that Ni_xCo_ (9-x) S_8@C for NiCo_2S_4/Ni_xCo _ (9-x) S_8 has superior capacitive performance, the current density is 2 Ag-1,3Ag-1,4Ag-1,5 Ag-1,6Ag-1,8Ag-1, respectively 14041200114711381000 Fg-1 and 580 Fg-1 capacitance, and 2000 cycles, the total capacity remained unchanged, showing good stability through the ring. Excellent electrochemical performance of N doped carbon coating and proof the hollow structure of the synergistic effect of sea urchin is beneficial to the increase of electrical conductivity, shorten the electron and ion diffusion path, accelerating electrode electrochemical reaction, enhance the electrochemical activity and stability of.4. SiO_2 microspheres as template, hollow carbon microspheres with uniform size distribution of MoS_2 coating prepared by hydrothermal method, the electrode material, the research the electrochemical performance, results showed that carbon hollow microspheres coated with MoS_2 at a current density of 100 mA g-1 after 100 cycles under the lithium capacity remains at 750 m Ah g-1; in the current density of 2 A g-1 lithium capacity can reach 349 mAh g-1. these results indicate that the carbon coated MoS_2 hollow microspheres can have a more prominent method of structure and performance advantages of.5. using thermal injected hexagonal nano SnSSe size of about 100nm synthesis in the oil phase than the traditional two-dimensional MoS_2 nano film in electrochemical storage, by two growth in its surface to achieve the Fe_2O_3 deposition, Fe_2O_3/SnSSe composites. The material composition, structure and morphology analysis and characterization, respectively Fe_2O_3/SnSSe and SnSSe nanosheets as anode materials for lithium ion batteries, found that lithium Fe_2O_3/SnSSe nanosheets have superior performance, can maintain 919 mAh g-1 capacity at a current density of 100 mA g-1, and mA in 200 g- after 100 cycles the capacity remains 755 mAh g-1. in addition, the work for the synthesis of other sulfur selenide Complexes and provides a new way to study their properties of lithium.

【学位授予单位】：内蒙古大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：TB383.1;O646

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