纳米结构氧化物基超级电容器电极设计与器件构造

发布时间：2018-01-07 00:27

本文关键词：纳米结构氧化物基超级电容器电极设计与器件构造　出处：《北京科技大学》2017年博士论文　论文类型：学位论文

【摘要】：超级电容器具有功率密度大、充放电速度快、使用寿命长等优势,是一种优良的储能器件,在电动汽车、现代通讯、航空航天以及国防设备等诸多领域拥有巨大的应用前景。但较低的能量密度一直制约其应用与发展,如何在保证高功率和长寿命优势的前提下,提高其能量密度是当今的研究热点。根据能量密度公式E=1/2CV~2,能量密度主要由电极材料电容量和器件电压窗口决定。本论文旨在研制具有高功率密度和能量密度的非对称型超级电容器。首先着眼于电极材料的可控制备、结构优化、能带设计以及储荷机理研究,以改善氧化物电极材料电化学性能,提高其电容量。在此基础上,设计构建了水系非对称超级电容器,实现器件工作电压窗口的拓宽。具体研究内容如F:1.通过掺杂改性优化正极材料的电输运性能提高电容量。设计构建了连续流动注入掺杂装置,通过连续恒定速率注入反应源,精确控制化学反应液的浓度,有效抑制了反应过程中Al~(3+)水解导致的生长液酸化的现象,可控制备了高载流子浓度的A1掺杂ZnO纳米线阵列,其载流子浓度可以达到1.14×10~(19)cm~(-3),与传统的掺杂方法相比(4.2×10~(16)cm~(-3)),载流子浓度提升了三个数量级。将这种高载流子浓度的A1掺杂ZnO纳米线作为活性物质NiO的导电支架,构筑自支撑电极材料,有效的提高了电极材料电容量。2.通过能带设计进一步优化正极材料界面电输运性能提高电容量。采用低温水热法在三维碳布基底上生长了 ZnO/NiO核壳结构纳米线阵列作为柔性自支撑电极。通过紫外光还原法在ZnO/NiO界面处嵌入Au纳米粒子,研究界面电输运性能对电极材料电容量的影响。当电流密度为5 mAcm-2时,ZnO/Au/NiO电极材料的电容量为4.1 Fcm~(-2),与ZnO/NiO电极材料(0.5 Fcm~(-2))相比提升了 720%。性能的提升主要归功于金纳米粒子可促进电极/电解液界面处电荷的快速传输。除此之外,在充电过程中,Au纳米粒子与NiO形成的界面肖特基势垒可以在费米能级处捕获少量电子,这将导致放电过程中,额外电子的释放。3.通过结构设计增加负极材料反应活性位点提高电容量。利用无模板水热法制备了 Fe_20_3中空梭状纳米颗粒,中空孔隙结构可以将电解液限制其中,在增加活性物质反应位点的同时,缩短了活性物质与电解液的之间的传输距离保证了离子的快速传输。当电流密度为0.5 Ag~(-1)时,电极材料比电容为249 Fg~(-1)。同时,引入阿伦尼乌斯公式分析了大电流密度下电容量下降的原因。在此基础上,考察了电极材料的温度服役行为。在20℃-60℃的温度范围内,随温度升高,电极材料电容量没有明显变化,表明该电极可以在20℃-60℃温度范围内稳定工作。4.构建非对称超级电容器拓宽电压窗口。通过设计利于界面电子传输的能带结构,在ZnO/Ni(OH)_2界面处引入TiO2嵌入层形成台阶状能带结构,制备了 ZnO/TiO_2/Ni(OH)_2核壳结构纳米线阵列作为正极材料。根据能带理论,台阶状能带结构可以减少充电过程中电子界面传输势垒,降低还原反应发生的激活能,电容量因此被提高。进一步通过水热法制备了ZnO/Fe_2O_3复合纳米材料作为超级电容器的负极,根据注入电荷平衡原则,正负电极材料质量配比为1.00:3.53,成功组装了非对称超级电容器。器件的电压窗口扩展到1.6V,电流密度1 Ag~(-1)时,非对称超级电容器可以获得146.8Fg~(-1)的比电容。功率密度为1350 Wkg~(-1)时,能量密度为52.22 Whkg~(-1)。
[Abstract]:Super capacitor with high power density, fast charging and discharging, long service life and other advantages, is an excellent energy storage device in electric vehicles, modern communication, has great application prospect in aerospace and defense equipment and other fields. But the low energy density restricted its application and development, how to in the premise of ensuring high power and long life advantages, improve the energy density is the hotspot of the research. According to the energy density formula of E=1/2CV~2, the energy density is mainly determined by the electrode capacitance and voltage window. This paper aims at the asymmetric super capacitor was developed with high power density and energy density of the controlled preparation of. First, optimize the structure of focusing on electrode materials, energy band design and storage mechanism, in order to improve the electrochemical performance of electrode materials, raise its capacity. On this basis, the design of construction The river asymmetricsupercapacitor, broaden the device operating voltage window. The specific contents such as F:1. by doping modification of cathode materials to improve the electrical transport properties. The capacitance is designed and constructed a continuous flow injection mixing device, injected into the reaction source through continuous constant speed, precise control of chemical reaction liquid concentration, effective suppression in the course of the reaction of Al~ (3+) in the growth solution hydrolysis acidification phenomenon, controlled synthesis of A1 doped ZnO nanowires with high carrier concentration of the array, the carrier concentration can reach 1.14 * 10~ (19) cm~ (-3), compared with the traditional method of doping (4.2 * 10~ (16) cm~ (-3)), the carrier concentration increased by three orders of magnitude. The A1 doped ZnO nanowires with high carrier concentration as the conductive support active material NiO, build a free-standing electrode material, effectively improve the capacitance of.2. electrode materials by band. Plan to further optimize the cathode material interface electrical transport properties to improve the capacitance. By low temperature hydrothermal method in three-dimensional carbon cloth substrate grown ZnO/NiO nanowires with core-shell structure array as a flexible self-supporting electrode. By UV reduction method in the interface of ZnO/NiO embedded Au nanoparticles, interface study of electrical transport properties of capacitance electrode materials. When the current density is 5 mAcm-2, the capacitance of the electrode materials of ZnO/Au/NiO 4.1 Fcm~ (-2), and ZnO/NiO electrode materials (0.5 Fcm~ (-2)) compared to enhance the 720%. performance mainly due to the gold nanoparticles can promote the rapid transmission of the electrode / electrolyte interface charge. In addition, in charge in the process, the interface of Schottky barrier Au nanoparticles and the formation of NiO can be captured at the Fermi level small electron, which will result in the discharge process, the release of.3. by additional electronic structure design increase Anode materials of reactive sites to improve capacity. Using the template free hydrothermal method, Fe_20_3 hollow spindle shaped nanoparticles prepared hollow pore structure can be increased in the limit of electrolyte, active substance reaction sites at the same time, shorten the transmission distance between the active material and the electrolyte to ensure fast ion transport. When the current density is 0.5 Ag~ (-1), electrode specific capacitance of 249 Fg~ (-1). At the same time, the introduction of Arrhenius formula, analyzed the reason of electric capacity decreased under high current density. On this basis, the temperature of the service behavior of electrode materials were investigated. The temperature range of 20 DEG -60 DEG C, with the increase of temperature, electrode the material capacity did not change significantly, show that the electrode can construct asymmetric supercapacitor voltage window to broaden the stable operation of the.4. at 20 DEG -60 DEG temperature range. The interface design for the electronic transmission The band structure in ZnO/Ni (OH) _2 interface into TiO2 embedded layer forming step band structure, to prepare ZnO/TiO_2/Ni (OH) _2 core-shell nanowire arrays as cathode materials. According to the band theory, stepped to the charging process can reduce the electronic interface transmission barrier band structure, reduction the reaction activation energy, the capacitance is thus improved. Further prepared by hydrothermal method ZnO/Fe_2O_3 nano composite material as cathode of supercapacitor, charge injection according to the principle of balance, positive and negative electrode material mass ratio is 1.00:3.53, successfully assembled asymmetricsupercapacitor devices. The voltage window is extended to 1.6V, current density of 1 Ag~ (-1), asymmetric super capacitor can be 146.8Fg~ (-1) capacitance. The power density is 1350 Wkg~ (-1), the energy density of 52.22 Whkg~ (-1).

【学位授予单位】：北京科技大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：TB383.1;TM53

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