金属氧化物多级结构的制备及其在超级电容器中的应用
发布时间：2018-12-14 10:50
【摘要】：随着对能源需求的增长和环境保护意识的增强,可持续发展的新能源及其相关的能源储存技术受到越来越多的关注。超级电容器被认为是一种十分具有潜力的储能器件,因为它具有高的功率密度,长的循环寿命以及快速的充放电性能。近年来,超级电容器的研究热点主要集中在制备容量高和循环性能好的电极材料上。其中金属氧化物电极材料因其具有较高的理论容量而备受关注,但是导电性差及循环寿命短的缺陷仍是制约金属氧化物材料发展的一大障碍。本文通过优化电极材料的纳米结构成功制备了几种结构不同的镍钴基金属氧化物电极材料,并系统的讨论了形貌与结构对电极材料电化学性能的影响。实验工作及成果如下:1.通过简单的水热法在泡沫镍上成功合成了核壳结构NiCo_2O_4@NiMoO_4的纳米片阵列。在最优的制备条件下,多级结构NiCo_2O_4@NiMoO_4电极的电化学活性要远远高于NiCo_2O_4单一组分电极。在电流密度为5mA cm-2时,复合电极的面积比容量和质量比容量分别为6.91 F·cm-2和1974 F·g-1,其在40 m A·cm-2的电流密度下循环5000次后的容量保持率为76%。此外,我们以活性炭为负极,最优条件下制备的核壳结构NiCo_2O_4@NiMoO_4的纳米片电极材料为正极,组装了非对称超级电容器,该电容器具有较高的能量密度和优异的循环性能。2.以相似的方法合成了NiCo_2O_4@CoMoO_4的纳米片阵列。由于纳米结构对活性材料独特的保护机制,复合电极展现了极为优异的电化学性能,高的面积比容量(在5 mA·cm-2电流密度下5.4 F·cm-2)、好的容量保持率及优秀的循环稳定性。由最优条件的电极与AC/grapheme复合材料组装的非对称超级电容器在593.5 W·kg-1的功率密度下拥有极高的能量密度42.75 Wh·kg-1。此外,该非对称电容器在10000个循环后容量几乎无衰减。3.通过水热法制备了镍铝双氢氧化物纳米片(Ni-Al LDH)阵列,然后以其为一层结构合成Ni-Al LDH@CoMoO_4纳米阵列电极,并讨论了水热时间对电极材料电化学性能的影响。
[Abstract]:With the increase of energy demand and the increasing awareness of environmental protection, more and more attention has been paid to the sustainable development of new energy sources and their related energy storage technologies. Supercapacitors are considered to be potential energy storage devices because of their high power density, long cycle life and fast charge-discharge performance. In recent years, the research focus of supercapacitors is mainly on the preparation of electrode materials with high capacity and good cycling performance. Among them, metal oxide electrode materials have attracted much attention because of their high theoretical capacity. However, the defects of poor conductivity and short cycle life are still a major obstacle to the development of metal oxide materials. In this paper, several kinds of nickel-cobalt based metal oxide electrode materials with different structures have been successfully prepared by optimizing the nanostructures of electrode materials, and the effects of morphology and structure on the electrochemical properties of electrode materials have been systematically discussed. The experimental work and results are as follows: 1. The core-shell NiCo_2O_4@NiMoO_4 nanoarrays were successfully synthesized on nickel foam by a simple hydrothermal method. Under the optimal preparation conditions, the electrochemical activity of multistage NiCo_2O_4@NiMoO_4 electrode is much higher than that of NiCo_2O_4 single component electrode. When the current density is 5mA cm-2, the area specific capacity and mass specific capacity of the composite electrode are 6.91 F cm-2 and 1974 F g-1, respectively. The capacity retention rate of the composite electrode after 5000 cycles at the current density of 40 Ma cm-2 is 76. In addition, we fabricated asymmetric supercapacitors using activated carbon as negative electrode and nanocrystalline electrode material of core-shell structure NiCo_2O_4@NiMoO_4 as positive electrode under optimal conditions. The capacitor has high energy density and excellent cycle performance. 2. NiCo_2O_4@CoMoO_4 nanochip arrays were synthesized in a similar way. Because of the unique protective mechanism of nanostructures on the active materials, the composite electrodes exhibit excellent electrochemical performance and high area specific capacity (5.4 F cm-2 at 5 mA cm-2 current density). Good capacity retention and excellent cycle stability. An asymmetric supercapacitor composed of an optimal electrode and AC/grapheme composite has an extremely high energy density of 42.75 Wh kg-1. at a power density of 593.5 W kg-1. In addition, the capacity of the asymmetric capacitor almost has no attenuation after 10,000 cycles. The nickel-aluminum dihydroxide (Ni-Al LDH) nanocrystalline arrays were prepared by hydrothermal method, and then the Ni-Al LDH@CoMoO_4 nanoscale array electrodes were synthesized by using them as a layer structure. The effect of hydrothermal time on the electrochemical properties of the electrode materials was discussed.
【学位授予单位】：电子科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TM53;TB383.1
本文编号：2378483
[Abstract]:With the increase of energy demand and the increasing awareness of environmental protection, more and more attention has been paid to the sustainable development of new energy sources and their related energy storage technologies. Supercapacitors are considered to be potential energy storage devices because of their high power density, long cycle life and fast charge-discharge performance. In recent years, the research focus of supercapacitors is mainly on the preparation of electrode materials with high capacity and good cycling performance. Among them, metal oxide electrode materials have attracted much attention because of their high theoretical capacity. However, the defects of poor conductivity and short cycle life are still a major obstacle to the development of metal oxide materials. In this paper, several kinds of nickel-cobalt based metal oxide electrode materials with different structures have been successfully prepared by optimizing the nanostructures of electrode materials, and the effects of morphology and structure on the electrochemical properties of electrode materials have been systematically discussed. The experimental work and results are as follows: 1. The core-shell NiCo_2O_4@NiMoO_4 nanoarrays were successfully synthesized on nickel foam by a simple hydrothermal method. Under the optimal preparation conditions, the electrochemical activity of multistage NiCo_2O_4@NiMoO_4 electrode is much higher than that of NiCo_2O_4 single component electrode. When the current density is 5mA cm-2, the area specific capacity and mass specific capacity of the composite electrode are 6.91 F cm-2 and 1974 F g-1, respectively. The capacity retention rate of the composite electrode after 5000 cycles at the current density of 40 Ma cm-2 is 76. In addition, we fabricated asymmetric supercapacitors using activated carbon as negative electrode and nanocrystalline electrode material of core-shell structure NiCo_2O_4@NiMoO_4 as positive electrode under optimal conditions. The capacitor has high energy density and excellent cycle performance. 2. NiCo_2O_4@CoMoO_4 nanochip arrays were synthesized in a similar way. Because of the unique protective mechanism of nanostructures on the active materials, the composite electrodes exhibit excellent electrochemical performance and high area specific capacity (5.4 F cm-2 at 5 mA cm-2 current density). Good capacity retention and excellent cycle stability. An asymmetric supercapacitor composed of an optimal electrode and AC/grapheme composite has an extremely high energy density of 42.75 Wh kg-1. at a power density of 593.5 W kg-1. In addition, the capacity of the asymmetric capacitor almost has no attenuation after 10,000 cycles. The nickel-aluminum dihydroxide (Ni-Al LDH) nanocrystalline arrays were prepared by hydrothermal method, and then the Ni-Al LDH@CoMoO_4 nanoscale array electrodes were synthesized by using them as a layer structure. The effect of hydrothermal time on the electrochemical properties of the electrode materials was discussed.
【学位授予单位】：电子科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TM53;TB383.1
【参考文献】
相关期刊论文 前1条
1 余丽丽;朱俊杰;赵景泰;;超级电容器的现状及发展趋势[J];自然杂志;2015年03期
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