过渡金属纳米材料的制备及其在超级电容器中的应用研究

发布时间：2018-05-07 14:09

本文选题：超级电容器 + 过渡金属　；参考：《内蒙古工业大学》2017年硕士论文

【摘要】：超级电容器作为一种新型绿色环保储能器件,因其具有高比电容、高功率密度、快速充放电、循环寿命长以及比传统电容器更高的能量密度等特点而被广泛关注,在电动汽车、航空航天、起重机蓄电系统、新能源发电等领域应用前景广阔,然而,与二次电池相比能量密度仍然较低,因此,提升能量密度是一直以来的研究重点。超级电容器的能量密度主要取决于比电容和电压窗口,而比电容很大程度上取决于电极材料的结构和形貌,因此,本文分别通过制备过渡金属硒化物纳米材料提升电极的导电性和比电容来改善超级电容器的能量密度,以及制备碳基纳米复合材料并组装成混合型超级电容器,从改进超级电容器结构出发进行能量密度提升。实验一通过温和可控的水热反应和硒代反应制得三维Ni_(0.85)Se纳米阵列材料,特殊的三维结构使Ni_(0.85)Se材料表现出良好的电化学性能。当电流密度为1 A·g~(-1)时,质量比电容为1160.41 F·g~(-1),面电容为4.64 F·cm~(-2)。通过对比可知其电性能比Ni O和Ni S高出数倍,说明硒化物更具电化学优势。此外,三维Ni_(0.85)Se纳米阵列材料具有良好的循环稳定性,组装成Ni_(0.85)Se//AC非对称超级电容器后表现出一定的储能特性。实验二采用同样的水热反应和硒代反应制得了类珊瑚状Ni_(0.9)Co_(1.92)Se_4纳米材料,通过扫描电镜、透射电镜等表征确定了电极材料的形貌特征和结构特点,随后进行电化学测试和电性能分析。当电流密度为1 A·g~(-1)时,质量比电容为1562.28 F·g~(-1),面电容为7.81 F·cm~(-2);尽管电流密度扩大到10 A·g~(-1),比电容保持率为69%,这在赝电容材料中处于较高水平,而且循环稳定性高达88.4%。组装成Ni_(0.9)Co_(1.92)Se_4//AC非对称超级电容器后,1 A·g~(-1)电流密度下比电容能达到175.73 C·g~(-1),与Ni_(0.85)Se//AC和Co_(0.85)Se//AC相比具有明显优势,尤其在大电流密度下能保持相对较高的比电容,同时,能量密度能达到40.42 Wh·kg~(-1),比当前多数超级电容器的储能更好。实验三采用声波化学合成法制得了Mn_3O_4/AC纳米复合材料,对其进行了基本的物相分析和形貌表征,并通过电化学测试得到材料在1 A·g~(-1)电流密度下,质量比电容能达到359.90 F·g~(-1),是单纯AC材料的2.2倍,即使电流密度扩大到10 A·g~(-1),比电容还能保持86%以上,说明复合材料保留了碳基材料倍率性能好的优点。同时,组装成Mn_3O_4/AC//1 M Li PF_6//Mn_3O_4/AC锂离子混合型超级电容器后发现,电容器的电压窗口扩大到3 V,能量密度也随之提升到54.20 Wh·kg~(-1),即使当功率密度扩大到9000W·kg~(-1),能量密度还能保持为31.68 Wh·kg~(-1),充分展现出Mn_3O_4/AC纳米复合材料在超级电容器领域的良好应用。
[Abstract]:As a new type of green energy storage devices, supercapacitors have been widely concerned because of their high specific capacitance, high power density, rapid charge and discharge, long cycle life and higher energy density than traditional capacitors. Aerospace, crane power storage system, new energy generation and other fields have broad application prospects. However, compared with secondary batteries, energy density is still relatively low, so increasing energy density is always the focus of research. The energy density of supercapacitors depends mainly on the specific capacitance and voltage window, and the specific capacitance largely depends on the structure and morphology of the electrode material. In this paper, the energy density of supercapacitors was improved by the preparation of transition metal selenide nano-material lifting electrodes and the specific capacitance, and the carbon matrix nanocomposites were prepared and assembled into hybrid supercapacitors. In order to improve the structure of supercapacitor, the energy density is raised. In the first experiment, three dimensional Ni_(0.85)Se nanoarrays were prepared by moderate and controllable hydrothermal reaction and selenide reaction. The special three-dimensional structure made the Ni_(0.85)Se materials exhibit good electrochemical performance. When the current density is 1 A / g ~ (-1), the mass specific capacitance is 1160.41 F / g ~ (-1) and the surface capacitance is 4.64 F / cm ~ (-2) ~ (-1). Compared with Ni O and Ni S, the electrical properties of selenides are several times higher than that of Ni O and Ni S, indicating that selenides have more electrochemical advantages. In addition, the three-dimensional Ni_(0.85)Se nanoarrays have good cyclic stability and exhibit certain energy storage characteristics after assembling into Ni_(0.85)Se//AC asymmetric supercapacitors. In experiment 2, coral-like Ni_(0.9)Co_(1.92)Se_4 nanomaterials were prepared by the same hydrothermal reaction and selenium reaction. The morphology and structure of the electrode materials were determined by SEM and TEM. Then electrochemical test and electrical performance analysis were carried out. When the current density is 1 A / g ~ (-1), the mass specific capacitance is 1562.28 F / g ~ (-1) and the surface capacitance is 7.81 F / cm ~ (-1) ~ (-1). Although the current density is increased to 10 A / g ~ (-1), the specific capacitance retention rate is 69 ~ (th), which is relatively high in the pseudo-capacitance materials, and the cycle stability is up to 88.4%. The specific capacitance of Ni_(0.9)Co_(1.92)Se_4//AC asymmetric supercapacitor can reach 175.73 C / g ~ (-1) at current density, which has obvious advantages over Ni_(0.85)Se//AC and Co_(0.85)Se//AC, especially it can keep a relatively high specific capacitance at high current density. The energy density can reach 40.42 Wh / kg ~ (-1), which is better than that of most supercapacitors. In experiment 3, Mn_3O_4/AC nanocomposites were synthesized by acoustic chemical synthesis. The phase and morphology of the composites were analyzed and characterized. The current density of Mn_3O_4/AC nanocomposites was obtained by electrochemical measurement at 1 A g ~ (-1). The mass specific capacitance can reach 359.90 F / g ~ (-1) ~ (-1), which is 2.2 times as high as that of pure AC material. Even if the current density is increased to 10 A / g ~ (-1), the specific capacitance can be maintained by more than 86%, which indicates that the composite retains the advantage of good performance of carbon based material. At the same time, after assembling Mn_3O_4/AC//1 M Li PF_6//Mn_3O_4/AC lithium ion hybrid supercapacitors, When the voltage window of the capacitor is enlarged to 3 V, the energy density increases to 54.20 Wh / kg ~ (-1). Even if the power density is increased to 9 000 W / kg ~ (-1), the energy density can be maintained at 31.68 Wh / kg ~ (-1), which fully demonstrates the good application of Mn_3O_4/AC nanocomposites in the field of supercapacitors.
【学位授予单位】：内蒙古工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TM53;TB383.1

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