纳米结构阳极氧化钛薄膜在超级电容器方面的应用

发布时间：2018-01-07 10:31

本文关键词：纳米结构阳极氧化钛薄膜在超级电容器方面的应用　出处：《南京理工大学》2017年硕士论文　论文类型：学位论文

【摘要】：超级电容器作为一种新型储能器件,近年来备受关注。阳极氧化钛(TiO_2)纳米管应用于超级电容器领域,具有比表面积大、便于电子传输、电位窗口宽等优点。然而,TiO_2纳米管作为半导体材料,导电性较差,且在可控制备方面仍有很多缺陷。本文旨在研究阳极氧化条件与纳米结构TiO_2薄膜形貌参数之间的关系,并通过进一步增大比表面积、掺杂改性等方法来改善TiO_2纳米管的电化学性能。首先,通过在常规电解液中加入乳酸(LA)、聚乙烯醇(PVA)等添加剂的方法,实现TiO_2纳米管的快速制备,生长速率最高可达1.9μmmin-1,并保持纳米管完整有序的结构;在高水含量电解液中制备出海绵状TiO_2薄膜,提高了TiO_2电极材料的比表面积;研究氧化电压(电流密度)、电解液温度、氧化次数等工艺参数对TiO_2薄膜形貌的影响,并通过二次氧化及升高氧化电压的方法改善了 TiO_2纳米管的规整度。其次,通过水热固-液法(Hydrothermal Solid-Liquid Route,HSLR)及水蒸气(Hydrothermal Solid-Gas Method,HSGM)处理的方法,制备出TiO_2纳米粒子/纳米管复合结构,研究处理温度、蒸气压、处理时间等因素对其形貌的影响。结果表明,复合结构的形成过程遵循溶解-重结晶机制,但HSLR处理会导致氧化膜易从基底上脱离,而HSGM处理可保持氧化膜与基底间的结合力,并显著增大TiO_2纳米管的比表面积。其中,蒸气压是控制复合纳米结构形貌的关键因素,加入水量180 μL进行HSGM处理的纳米管(HSGM-180)比表面积高达70.8m2g~(-1),是未处理TiO_2纳米管的3.16倍。保持蒸气压处于饱和状态,处理20 min便可获得理想的复合纳米结构(HSGM-20min)。再次,将TiO_2纳米粒子/纳米管复合结构在Ar、NH3气氛中进行退火改性,进一步提高其电化学性能。实验发现,NH3退火虽可大幅提高TiO_2电极材料的比电容,但会导致其电化学性能不稳定,倍率特性、循环稳定性较差;而Ar退火可生成氧空位,降低电极材料的内阻,Ar退火的HSGM-20min比电容可达76.12mFcm~(-2),是空气退火的未处理TiO_2纳米管的5.49倍,且循环2000圈后比电容仍维持在初始值的87.7%。最后,在含有金属离子的溶液中,通过电化学恒压或恒流掺杂的方法对TiO_2纳米管进行掺杂改性。结果表明,在非水溶液中Al~(3+)可嵌入TiO_2的晶格结构,克服H掺杂循环稳定性较差的缺点,并生成更多的氧空位,而Fe~(3+)及Cu_(2+)则无法嵌入TiO_2的结构中。-3 mA cm~(-2)下恒流Al~(3+)掺杂TiO_2纳米管的比电容为8.41 mF cm~(-2),是未掺杂纳米管的3.77倍,循环2000次后电容维持率仍高达93.4%。
[Abstract]:As a new type of energy storage devices, supercapacitors have attracted much attention in recent years. Anodic titanium oxide TiO-2) nanotubes are used in the field of supercapacitors, which have large specific surface area and are convenient for electronic transmission. However, TiO2 nanotubes, as semiconductor materials, have poor electrical conductivity. And there are still many defects in the controllable preparation. The purpose of this paper is to study the relationship between the anodic oxidation conditions and the morphology parameters of nanostructured TiO_2 films, and to further increase the specific surface area. The electrochemical properties of TiO_2 nanotubes were improved by doping and modifying. Firstly, additives such as lactic acid and polyvinyl alcohol were added into the conventional electrolyte. The rapid preparation of TiO_2 nanotubes was achieved, the growth rate was up to 1.9 渭 m min-1, and the structure of the nanotubes remained intact and ordered. Spongy TiO_2 thin films were prepared in high water content electrolyte, which improved the specific surface area of TiO_2 electrode materials. The effects of oxidation voltage (current density, electrolyte temperature, oxidation times) on the morphology of TiO_2 films were studied. The regularity of TiO_2 nanotubes was improved by secondary oxidation and increasing oxidation voltage. Secondly. Hydrothermal Solid-Liquid Route was obtained by hydrothermal solid-liquid method. HSLR) and water vapor Solid-Gas method (HSLR). The composite structure of TiO_2 nanoparticles / nanotubes was prepared, and the effects of treatment temperature, vapor pressure and treatment time on the morphology of the nanotubes were studied. The formation of the composite structure follows the mechanism of dissolution-recrystallization, but HSLR treatment can easily separate the oxide film from the substrate, while the HSGM treatment can maintain the adhesion between the oxide film and the substrate. The vapor pressure is the key factor to control the morphology of composite nanostructures. The specific surface area of HSGM-180 was 70.8 m ~ (2) g ~ (-1) in HSGM treated with 180 渭 L water. It is 3.16 times as high as that of untreated TiO_2 nanotubes. The ideal composite nanostructures can be obtained after 20 minutes of treatment by keeping the vapor pressure in saturated state. The composite structure of TiO_2 nanoparticles / nanotubes was annealed in ArnNH _ 3 atmosphere to further improve its electrochemical performance. NH3 annealing can increase the specific capacitance of TiO_2 electrode material, but it will lead to the instability of electrochemical performance, the rate characteristics and the poor cycle stability. The oxygen vacancy can be formed by ar annealing, and the HSGM-20min specific capacitance of ar annealing can reach 76.12 mFcm-2). It is 5.49 times that of the untreated TiO_2 nanotubes annealed in air, and the specific capacitance is still 87.7% of the initial value after 2000 cycles. Finally, in the solution containing metal ions. The doping modification of TiO_2 nanotubes was carried out by electrochemical constant voltage or constant current doping. The results show that Al~(3 can be embedded in the lattice structure of TiO_2 in non-aqueous solution. The shortcomings of H doping cycle stability are overcome and more oxygen vacancies are generated. Fe~(3) and Cu_(2) could not be embedded in the structure of TiO_2. The specific capacitance of doped TiO_2 nanotubes is 8.41 MF / cm ~ (-2). It is 3.77 times as high as that of undoped nanotubes, and the capacitance maintenance rate is as high as 93.4after 2000 cycles.
【学位授予单位】：南京理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TB383.2;TM53

【参考文献】