二氧化锰复合材料的制备及超电容性能的研究

发布时间：2018-01-01 13:32

本文关键词：二氧化锰复合材料的制备及超电容性能的研究　出处：《上海交通大学》2015年硕士论文　论文类型：学位论文

【摘要】：超级电容器具有寿命长、功率密度高等优点,被认为是最具有潜力的储能设备之一。超级电容器根据储能机理可以分为两类,即双电层超级电容器和赝电容超级电容器。目前,作为赝电容超级电容器电极材料的过渡金属氧化物是研究的重点,其中研究较早的有RuO2、Co3O4、VOx等材料,但是由于价格昂贵、毒性较大,这些材料难以大规模推广。二氧化锰具有比容量高(理论容量达到1100~1300 F g-1)、价格低廉、毒性低、储藏丰富以及环境友好等优点是近期超级电容器电极材料研究的热点。本文立足于二氧化锰材料,对材料的形貌和电化学性能进行了研究。同时,制备了二氧化锰复合材料,以期获得性能更好的材料。主要的内容有:(1)通过一步光驱动合成法高效的制备了一系列MnO2材料,并探究了不同光照时间对材料的形貌和电化学性能的影响。通过控制光照时间的不同,样品的形貌得到控制。合成开始的时候,样品开始慢慢由小片簇集而成,形成表面带刺状的疏松实心小球。到了10分钟的时候,纳米片继续堆积在小球的表面,而内部则逐渐收缩。直到20分钟左右,核与壳分离开来,形成蛋黄-壳状结构。然后核开始慢慢的变小,直至消失,最终在40分钟左右的时候形成空心结构。光驱动合成法制备的材料均具有较大的比表面积,疏松的结构也更加利于离子的传输,保证了材料较大的比电容和循环稳定性。在1.0 mV s-1的低扫描速度下,在光照时间分别为5、10、20和40分钟时材料的比电容分别为200、158、155和173 F g-1。在1000次恒电流充放电循环后,5、10、20和40分钟时材料的效率分别为85%、89%、98%和87%。从循环寿命和倍率性能上面来看,20分钟是最合适的反应时间。(2)选取20分钟作为实验的光照时间,使用光驱动合成法制备了钴掺杂的MnO2材料,通过改变Co离子的加入量获得了不同钴掺杂量的样品。X射线衍射分析表明,随着钴掺杂量的增加,峰位有较明显的往低角度移动的趋势。证明了Co掺杂到MnO2材料的晶格之中了。在未掺杂钴的MnO2的高分辨率透射电镜图像中,约0.24 nm的晶格条纹间距可以很好地与斜方锰矿型MnO2的(210)晶面间距匹配,在钴掺杂后,(210)晶面的晶格条纹间距开始变宽增加至0.26 nm,这与X射线衍射分析的结果吻合。钴掺杂后的材料表现出了更好的电化学性能,在1.0 mV s-1的扫描速度下,掺杂量在2%的材料具有最高的比电容,达287 F g-1,即使在20 mV s-1的高扫描速度下也能维持50%以上的比电容。(3)通过3-氨丙基三甲基硅烷对氧化石墨烯进行改性并合成了不同比例石墨烯包覆的MnO2材料,用作超级电容器电极材料上。X射线衍射、扫描电镜和透射电镜等的结果表明,石墨烯能够均匀并有效的包覆在MnO2小球的表面。石墨烯复合MnO2材料表现出优异的电化学性能,包括较高的比电容、倍率性能和循环寿命等。复合材料在1.0 mV s-1的扫描速度下比电容为312 F g-1,是MnO2同等扫速下的两倍,同时其在50.0 mV s-1时仍能保持96%以上的电容。复合材料在1000次恒电流充放电后比电容均能够保留初始的90%。交流阻抗测试结果表明,石墨烯复合MnO2材料相比纯MnO2材料有更小的阻抗、较大的电导率,从而获得了更加优异的电化学性能。
[Abstract]:The super capacitor has the advantages of long service life, high power density, is considered the most promising energy storage equipment. According to one of the super capacitor energy storage mechanism can be divided into two categories, namely the electric double layer capacitor and pseudocapacitive super capacitor. At present, as the transition metal oxide pseudocapacitance supercapacitor electrode materials is the focus of the study, the earlier research by RuO2, Co3O4, VOx and other materials, but because the price is expensive, toxic, these materials are difficult to large-scale promotion. Manganese dioxide having high specific capacity (theoretical capacity of 1100~1300 F g-1), low price, low toxicity, rich and environmentally friendly advantages is the focus of recent studies super capacitor electrode material. Based on the materials of manganese dioxide, morphology and electrochemical properties of materials were studied. At the same time, manganese dioxide composite material was prepared, in order to obtain the performance Better material. The main contents are as follows: (1) by one step synthesis method for efficient light driven a series of MnO2 materials were prepared, and explore the effects of different illumination time on structure and electrochemical properties of the material. By controlling the time of illumination, the morphology of the samples under control. When the synthesis started a sample, start slowly by small clusters, loose solid ball is formed on the surface of spiny. In the 10 minutes, nanosheets continue to pile up in the surface of the pellets, and it gradually shrink. Until 20 minutes, core and shell are separated to form yolk shell structure. Then the nucleus began to slowly the smaller, until it disappears, the final time in 40 minutes to form a hollow structure. The light driven synthesis materials have large specific surface area, porous structure is more conducive to the ion transport, ensure the material is larger than the capacitance and The cyclic stability. At low scan rate of 1 mV s-1, in the light of the time were 5,10,20 and 40 minutes of material specific capacitance were 200158155 and 173 F g-1. 1000 times in the constant current charge discharge cycles, 5,10,20 and 40 minutes when the material efficiency were 85%, 89%, 98% and 87%. from circulation life and rate performance above 20 minutes, the reaction time is most appropriate. (2) selected 20 minutes as the illumination time, using light driven synthesis of cobalt doped MnO2 materials were prepared by adding the amount of change, Co ion obtained samples of different cobalt doped.X ray diffraction analysis shows that with the increase of CO doping amount, the peak has obvious trend to move to the low angle. It is proved that the Co doped MnO2 materials. The lattice in high resolution transmission electron microscopy images without cobalt doped MnO2, the lattice fringe spacing of about 0.24 nm can be Good MnO2 and ramsdellite type (210) spacing matching in cobalt doped, (210) crystal plane lattice fringe spacing becomes wide increased to 0.26 nm, the X analysis and X-ray diffraction results. Cobalt doped materials showed better electrochemical performance, the scanning speed is 1 mV s-1, the doping amount in 2% materials with the highest specific capacitance of 287 F g-1, even at high scan rate of 20 mV S-1 can maintain more than 50% of the specific capacitance. (3) the modification of graphene oxide 3- three aminopropyl methyl silane and the synthesis of different proportion graphene coated MnO2 materials as electrode material of super capacitor on.X ray diffraction, scanning electron microscopy and transmission electron microscopy. The results show that the surface of graphene can effectively and uniformly coated on the MnO2 ball. Graphene MnO2 composites exhibit excellent electrochemical properties, including high The specific capacitance, rate performance and cycle life. The composite scan rate at 1 mV S-1 the specific capacitance of 312 F g-1, MnO2 is two times the speed of the same scan at the same time, in the 50 mV S-1 can still maintain capacitance. More than 96% of the composite materials in the 1000 constant current charge discharge specificcapacitance are able to retain 90%. impedance test results show that the initial, graphene MnO2 composites compared with the pure MnO2 material has smaller impedance, high conductivity, so as to obtain more excellent electrochemical performance.

【学位授予单位】：上海交通大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TQ137.12;TM53

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