發(fā)布時間：2018-01-06 15:16

  本文關(guān)鍵詞：金屬氧化物納米結(jié)構(gòu)的合成及電化學(xué)儲鋰性能研究　出處：《青島科技大學(xué)》2017年碩士論文　論文類型：學(xué)位論文

  更多相關(guān)文章： 二氧化硅 氧化鐵 鉬酸鈷 二硫化鉬 中空納米結(jié)構(gòu) 鋰離子電池

【摘要】：隨著工業(yè)經(jīng)濟的迅速發(fā)展和環(huán)境治理的日益緊迫,人們希望得到越來越多的清潔能源�；剂弦蚱湮廴緡乐厍也豢稍偕呀�(jīng)無法滿足社會的需求,開發(fā)清潔高效的新型能源是大勢所趨,早已成為人們關(guān)注的熱點。鋰離子電池作為一種新型的能量儲存和轉(zhuǎn)化裝置,已經(jīng)廣泛應(yīng)用于各種小型電子設(shè)備,并且在電動車電源和太陽能、風(fēng)能等可再生能源的儲存方面有廣闊的應(yīng)用前景。鋰離子電池的電極材料是影響其性能的關(guān)鍵,目前商業(yè)化的石墨類材料理論容量低且有安全性問題,因此亟需開發(fā)其他高能量、高穩(wěn)定性的新型鋰離子電池負極材料。過渡金屬氧化物具有高容量、優(yōu)異的循環(huán)性能和安全性能等優(yōu)點,是替代石墨的理想電池負極材料,然而其導(dǎo)電性差、不可逆容量大以及充放電前后體積變化大等問題在很大程度上制約了其實際應(yīng)用。研究發(fā)現(xiàn),通過納米化、形貌控制、碳包覆可以有效地提高材料的導(dǎo)電性,緩解充放電時的體積膨脹,改善材料的電化學(xué)性能。另外,氫能作為另外一種清潔能源也受到了人們的廣泛關(guān)注,如何高效地從水中制取氫氣是目前的研究熱點之一。而電催化析氫反應(yīng)被認為是一種高效產(chǎn)氫的方式,但是作為電催化析氫反應(yīng)催化劑的貴金屬價格昂貴、儲量貧乏,因此急需尋找一種高效、經(jīng)濟的催化劑。過渡金屬硫化物可以作為一種高效的析氫催化劑替代以往的貴金屬催化劑,但是如何進一步提高過渡金屬硫化物的催化活性依然是一個限制因素。研究發(fā)現(xiàn)合成特殊形貌的過渡金屬硫化物納米結(jié)構(gòu)或者與其他材料摻雜都可以有效的改善催化活性。本論文采用水熱法制備過渡金屬氧化物和硫化物材料,應(yīng)用X-射線衍射(XRD)、掃描電鏡(SEM)和透射電鏡(TEM)等技術(shù)分析材料的形貌和結(jié)構(gòu)等物理特征,運用恒電流充放電、循環(huán)伏安(CV)和交流阻抗譜(EIS)等技術(shù)測試材料的電化學(xué)性能,并分析了材料的結(jié)構(gòu)和形貌與電化學(xué)性能之間的關(guān)系。主要研究內(nèi)容和結(jié)果如下:(1)在前驅(qū)體FeOOH表面構(gòu)造二氧化硅包覆層,在二氧化硅包覆層的保護作用下,氧化鐵材料能夠保持前驅(qū)體的一維納米結(jié)構(gòu)。煅燒過程中,前驅(qū)體FeOOH轉(zhuǎn)變成氧化鐵,同時發(fā)生脫水在材料表面形成多孔的結(jié)構(gòu)。這種獨特的多孔一維納米結(jié)構(gòu)有利于鋰離子的嵌入-脫出和電子的快速遷移,同時表面的微孔又可以有效的緩解電極在充放電過程中的體積變化,提高循環(huán)穩(wěn)定性。(2)利用一種簡易方式在二氧化硅表面構(gòu)筑超薄CoMoO_4納米片,同時腐蝕掉位于中心的二氧化硅模板,制備出CoMoO_4納米片組裝的中空納米結(jié)構(gòu)。放射狀的直立片層結(jié)構(gòu)可以為鋰離子的嵌入提供更多的位置,內(nèi)部的中空結(jié)構(gòu)可以有效的緩解材料的體積效應(yīng),因此材料具有良好的儲鋰性能。在500 mA·g-1的電流密度下循環(huán)200圈,放電容量依然可以達到1066 mAh·g-1,容量保持率為93%,庫倫效率為98%。由于材料特定的中空結(jié)構(gòu)和大的表面積使其實際容量要高于CoMoO_4的理論容量。在10 A·g-1的電流密度下,CoMoO_4中空納米結(jié)構(gòu)依然可以保留較高的可逆容量為470 mAh·g-1,數(shù)值仍然高于石墨的理論容量372 mAh·g-1。結(jié)果表明材料具有良好的倍率性能和循環(huán)穩(wěn)定性。(3)通過在四氧化三鐵納米球模板的表面包覆二硫化鉬納米片,合成Fe3O_4@MoS_2異質(zhì)結(jié)構(gòu)材料,作為電催化析氫反應(yīng)的催化劑。經(jīng)過測試證明這種特殊結(jié)構(gòu)的Fe3O_4@MoS_2材料具有比空心二硫化鉬更好的析氫催化性能。計算結(jié)果顯示,材料的電催化活性面積為空心二硫化鉬的兩倍;四氧化三鐵的加入也提高了材料單位面積上活性位點的催化活性。
[Abstract]:With the rapid development of industrial economy and environment is increasingly urgent, people hope to get more and more clean energy. Because of the serious pollution of fossil fuels and non renewable has been unable to meet the needs of society, the new development of clean and efficient energy is already represent the general trend, as the focus of attention. The lithium ion battery as an energy storage and conversion device, has been widely used in a variety of small electronic devices, and the electric power and solar energy, has wide application prospect in storage, wind and other renewable energy. The electrode materials of lithium ion battery is the key to affect the performance of the current commercial graphite materials have low theoretical specific capacity and security issues therefore, it is necessary to develop other high energy, new anode material for lithium ion battery with high stability. The transition metal oxide has the advantages of high capacity, excellent cycle Energy and safety performance and other advantages, is the ideal battery cathode materials to replace graphite, but its poor conductivity, the irreversible capacity and charge discharge before and after volume change and restricts its practical application to a great extent. The study found that the morphology control of nano carbon coating, and can effectively improve the conductivity of the material the ease, charge and discharge volume expansion, improve the electrochemical properties of the material. In addition, hydrogen as another clean energy has attracted people's attention, how to efficiently produce hydrogen from water is one of the research hotspots. The electrocatalytic hydrogen evolution reaction is considered to be an efficient way to produce hydrogen. But as the price of the precious metal catalytic hydrogen evolution reaction catalyst is expensive, poor reserves, it is urgent to find an efficient and economical catalyst. Transition metal sulfides can be used as an efficient hydrogen evolution Catalysts instead of noble metal catalysts in the past, but how to further improve the catalytic activity of transition metal sulfides is still a limiting factor. The study found that transition metal sulfide nanostructures with special morphology or with other materials doped can improve the catalytic activity effectively. This paper adopts the hydrothermal synthesis of transition metal oxides and sulfides, application X- ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) technique. The morphology and structure of materials and other physical characteristics, using constant current charge discharge, cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) techniques such as electrochemical performance test materials, and analyzes the relationship between material the structure and morphology and electrochemical performance. The main research contents and results are as follows: (1) in the precursor FeOOH surface structure of silica coated layer protection in two oxygen silicon coating Under the influence of iron oxide material can keep the one-dimensional nano structure of precursor. The calcination process, the precursor FeOOH into iron oxide, simultaneous dehydration to form a porous structure on the surface of the material. This unique porous nanostructures have rapid migration for lithium ions and electron - intercalation, while the surface pores can alleviate again the volume change of electrode during the charge discharge process effectively, improve the cycle stability. (2) using a simple way to construct ultrathin CoMoO_4 nanosheets on silica surface and etching is located in the center of the two silica template prepared CoMoO_4 nanosheets assembled hollow nanostructures. Vertical lamellar structure of radial for lithium ion insertion to provide more position inside the hollow structure can reduce the volume effect of the material effectively, so the material has good lithium storage performance in 500. The current density of mA and g-1 under 200 cycles, the discharge capacity can reach 1066 mAh - g-1, the capacity retention rate was 93%, the efficiency of Kulun for 98%. with a theoretical capacity of hollow structure specific materials and large surface area to the actual capacity is higher than that of CoMoO_4. In the current 10 A - g-1 density. CoMoO_4 hollow nanostructures can still retain the higher reversible capacity of 470 mAh - g-1, the value is still higher than the theoretical capacity of graphite is 372 mAh - g-1. results show that the material has good cycling performance and rate capability. (3) on the surface of Fe3O4 nanospheres by template coated with molybdenum disulfide, synthesis of Fe3O_4@MoS_2 heterostructure materials as catalyst electrocatalytic hydrogen evolution reaction. After testing the special structure of the Fe3O_4@MoS_2 material has better catalytic performance than MoS2 hollow hydrogen. The calculation results show that the material The active area of the electrocatalytic activity is two times of that of the hollow molybdenum disulfide, and the addition of iron oxide also improves the catalytic activity of the active site on the unit area of the material.

【學(xué)位授予單位】：青島科技大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TB383.1;TM912

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