一维聚吡咯纳米管的制备及其在锂空气电池中的应用
发布时间：2018-09-12 11:51
【摘要】：在现有的电池体系中,锂空气电池因具有最高的理论容量密度(约为锂离子电池的10倍以上),将有望可以解决电动车续航能力严重不足的难题,甚至可以极大缓解目前所面临的能源与环境危机。尽管如此,对处于实验室研发阶段的锂空气电池来说,仍然有很多问题(如大倍率性能、循环寿命、放电深度等)亟待解决。为此研究人员主要从两个方面出发,一是开发性能优异的电极材料/催化剂,一是寻找综合性能优异的电解液/质。在电极材料的研究方面,以往的研究主要集中于质轻、孔丰富、导电性好、化学性质稳定的碳基材料。经过微观架构、层次孔的设计,锂空电池的电化学性能确实得到了飞跃的提高。但是随着研究的深入,发现碳基材料的孔利用率并不如预期那么高,并且其化学稳定性也不够理想。因此,寻找廉价、活性高、稳定性好的空气电极材料显得尤为必要。导电聚吡咯因具有导电性可调、微观形貌可控、电化学活性高等优点,可被用作锂空电池的电极材料。因此,通过微观形貌、电导率的调制,研究导电聚吡咯基空气电极在锂空气电池中的应用具有比较重要的理论意义。本课题主要通过一维纳米结构聚吡咯基空气电极材料的微观结构和电导率的设计来研究其电化学响应,研究内容主要包括一维纳米结构聚吡咯形成机理的研究;具有典型微观形貌聚吡咯基空气电极的电化学行为研究。得出以下结论:(1)系统研究了自组装软模板甲基橙浓度对聚吡咯微观形貌和电导率的影响。发现,随甲基橙模板浓度升高,聚吡咯的微观形貌经历了一个由颗粒转变为棒状的演化,并且随浓度增加聚吡咯纳米棒直径逐渐减小;模板浓度的增加有利于吡咯单体α-α位的聚合,从而导致了聚吡咯导电率的上升。当甲基橙模板的浓度达到5 mM时,其导电率达到最大值为16.7 S/cm,比颗粒状聚吡咯的电导率高一个数量级。(2)系统研究了氧化剂用量对聚吡咯微观形貌和电导率的影响。发现,随氧化剂(FeCl3)加入量的增加,聚吡咯形貌由残缺的管状结构发育为完整的管状结构,在结构上的共轭程度呈先增加后减小的趋势,表现在导电率上为先上升后下降。当氧化剂(FeCl3)与单体(Py)的物质的量之比为3:2,聚吡咯导电率达到最大值49.7 S/cm。(3)系统研究了吡咯(Py)单体用量对聚吡咯微观形貌的影响。发现,随Py增加,聚吡咯的微观形貌由片状和残缺的管状结构逐渐聚合为完整的棒状结构,并且随着Py量的增加,聚吡咯纳米棒直径基本保持不变。聚吡咯在模板上的生长具有一定的取向性,在垂直方向上由外及内逐渐生长,在水平方向上沿管壁方向生长。(4)初步研究了具有典型微观形貌(开口管状和多针状)一维纳米结构聚吡咯空气电极的电化学响应。发现,在100 mA/g的电流密度下,开口结构的聚吡咯纳米管空气电极的放电比容量高达2300 m Ah/g,在电流密度提高到300 mA/g时容量损失只有5%,表现出了良好的倍率性能,在所有形貌的一维聚吡咯中拥有最高的氧还原(ORR)和氧氧化(OER)活性,但其循环性能需要进一步改善。
[Abstract]:In the existing battery system, lithium-air batteries with the highest theoretical capacity density (about 10 times more than lithium-ion batteries), will hopefully be able to solve the problem of insufficient endurance of electric vehicles, and even greatly alleviate the current energy and environmental crisis. There are still many problems to be solved urgently for gas batteries, such as high-rate performance, cycle life, discharge depth, etc. Therefore, researchers mainly start from two aspects, one is to develop excellent electrode materials / catalysts, the other is to find electrolytes / materials with excellent comprehensive performance. The electrochemical performance of lithium-air batteries has been improved by leaps and bounds after the design of micro-structure and layered pore. However, with the further study, it is found that the pore utilization rate of carbon-based materials is not as high as expected, and their chemical stability is not ideal. Therefore, it is necessary to find a cheap, active and stable air electrode material. Conducting polypyrrole can be used as electrode material for lithium-air batteries because of its adjustable conductivity, controllable micro-morphology and high electrochemical activity. In this paper, the electrochemical response of one-dimensional nanostructured polypyrrole-based air electrode materials was studied by designing the microstructure and conductivity of the materials. The research contents mainly include the formation mechanism of one-dimensional nanostructured polypyrrole; typical micro-morphology of polypyrrole-based holes The results are as follows: (1) The effect of the concentration of methyl orange on the morphology and conductivity of polypyrrole was studied systematically. It was found that the morphology of polypyrrole changed from particle to rod with the increase of the concentration of methyl orange template. When the concentration of methyl orange template reached 5 mM, the conductivity of polypyrrole was 16.7 S/cm, which was one order of magnitude higher than that of granular polypyrrole. It is found that the morphology of polypyrrole develops from incomplete tubular structure to intact tubular structure with the increase of the amount of oxidant (FeCl3). The degree of conjugation increases first and then decreases. The conductivity increases first and then decreases. When the amount of oxidant (FeCl3) and monomer (Py) is added, the morphology of polypyrrole develops from incomplete tubular structure to intact tubular structure. (3) The effect of the amount of pyrrole monomer on the morphology of polypyrrole was studied systematically. It was found that with the increase of Py, the morphology of polypyrrole gradually polymerized from lamellar and incomplete tubular structures to complete rod-like structures, and with the increase of Py content, the polypyrrole nanorods were straight. The diameter of the polypyrrole is basically unchanged. The growth of the polypyrrole on the template has a certain orientation, growing from outside to inside in the vertical direction, and growing along the wall of the tube in the horizontal direction. (4) The electrochemical response of the polypyrrole air electrode with typical micro-morphology (open tubular and multi-needle) has been studied preliminarily. At the current density of mA/g, the discharge specific capacity of the open-ended polypyrrole nanotube air electrode is as high as 2300 m Ah/g. When the current density is increased to 300 mA/g, the capacity loss is only 5%. The polypyrrole exhibits good rate performance, and has the highest oxygen reduction (ORR) and oxygen oxidation (OER) activity in all morphologies of the one-dimensional polypyrrole, but its cyclicity is good. It needs further improvement.
【学位授予单位】：深圳大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TQ317;TM911.41
本文编号：2238921
[Abstract]:In the existing battery system, lithium-air batteries with the highest theoretical capacity density (about 10 times more than lithium-ion batteries), will hopefully be able to solve the problem of insufficient endurance of electric vehicles, and even greatly alleviate the current energy and environmental crisis. There are still many problems to be solved urgently for gas batteries, such as high-rate performance, cycle life, discharge depth, etc. Therefore, researchers mainly start from two aspects, one is to develop excellent electrode materials / catalysts, the other is to find electrolytes / materials with excellent comprehensive performance. The electrochemical performance of lithium-air batteries has been improved by leaps and bounds after the design of micro-structure and layered pore. However, with the further study, it is found that the pore utilization rate of carbon-based materials is not as high as expected, and their chemical stability is not ideal. Therefore, it is necessary to find a cheap, active and stable air electrode material. Conducting polypyrrole can be used as electrode material for lithium-air batteries because of its adjustable conductivity, controllable micro-morphology and high electrochemical activity. In this paper, the electrochemical response of one-dimensional nanostructured polypyrrole-based air electrode materials was studied by designing the microstructure and conductivity of the materials. The research contents mainly include the formation mechanism of one-dimensional nanostructured polypyrrole; typical micro-morphology of polypyrrole-based holes The results are as follows: (1) The effect of the concentration of methyl orange on the morphology and conductivity of polypyrrole was studied systematically. It was found that the morphology of polypyrrole changed from particle to rod with the increase of the concentration of methyl orange template. When the concentration of methyl orange template reached 5 mM, the conductivity of polypyrrole was 16.7 S/cm, which was one order of magnitude higher than that of granular polypyrrole. It is found that the morphology of polypyrrole develops from incomplete tubular structure to intact tubular structure with the increase of the amount of oxidant (FeCl3). The degree of conjugation increases first and then decreases. The conductivity increases first and then decreases. When the amount of oxidant (FeCl3) and monomer (Py) is added, the morphology of polypyrrole develops from incomplete tubular structure to intact tubular structure. (3) The effect of the amount of pyrrole monomer on the morphology of polypyrrole was studied systematically. It was found that with the increase of Py, the morphology of polypyrrole gradually polymerized from lamellar and incomplete tubular structures to complete rod-like structures, and with the increase of Py content, the polypyrrole nanorods were straight. The diameter of the polypyrrole is basically unchanged. The growth of the polypyrrole on the template has a certain orientation, growing from outside to inside in the vertical direction, and growing along the wall of the tube in the horizontal direction. (4) The electrochemical response of the polypyrrole air electrode with typical micro-morphology (open tubular and multi-needle) has been studied preliminarily. At the current density of mA/g, the discharge specific capacity of the open-ended polypyrrole nanotube air electrode is as high as 2300 m Ah/g. When the current density is increased to 300 mA/g, the capacity loss is only 5%. The polypyrrole exhibits good rate performance, and has the highest oxygen reduction (ORR) and oxygen oxidation (OER) activity in all morphologies of the one-dimensional polypyrrole, but its cyclicity is good. It needs further improvement.
【学位授予单位】：深圳大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TQ317;TM911.41
【参考文献】
相关期刊论文 前1条
1 郭向欣;黄诗婷;赵宁;崔忠慧;范武刚;李驰麟;李泓;;二次锂空气电池研究的快速发展及其急需解决的关键科学问题[J];无机材料学报;2014年02期
，本文编号：2238921
本文链接：https://www.wllwen.com/kejilunwen/dianlidianqilunwen/2238921.html
