锰化合物微纳结构的构筑调控及其电化学储能应用

发布时间：2018-04-29 12:51

本文选题：中空核壳结构 + 掺杂　；参考：《太原理工大学》2017年硕士论文

【摘要】：随着气候变化以及可用化石能源的不断减少,现代社会开始逐渐寻求利用可持续以及可再生能源(例如风能、太阳能)。为了更高效的利用这些可再生能源,能量存储系统的开发也变得越来越重要。电化学储能装置由于有较高的能量转换效率受到研究者的广泛关注。典型的电化学储能器件为锂离子电池与超级电容器,它们被大量应用在便携式电子产品、混合电动汽车以及大型工业设备上,这些都需要器件具有较高的能量密度、功率密度和长循环寿命,而其优异性能实现的关键因素为电极材料的设计及改性。过渡金属氧化物不仅具有较好的储锂能力而且还具有良好的赝电容性质。其中,三氧化二锰有较高的的理论比容量(1018 mA h g~(-1)),环境友好,储量丰富,是一种比较有前景的锂电池电极材料;碳酸锰制备简单,成本低廉,赝电容性能优良。但是三氧化二锰的电导率较低,充放电过程中由于锂脱嵌带来的体积变化通常会导致其倍率性能差,循环寿命低;同样碳酸锰也存在导电性较差的问题。基于上述问题,如何对材料进行合理地结构设计及改性对于提高器件的电化学储能性能具有重要意义。本论文旨在通过对电极材料进行简单的结构设计及改性研究,为发展制备性能优异的电化学储能材料提供有益的探索。本论文主要研究内容如下:(1)采用模板法合成了具有中空的三氧化二锰核壳结构。透射电子显微镜的表征表明合成的三氧化二锰材料是由尺寸均一的纳米粒子自组装的微球,核与壳之间具有明显的中空部分,外层的壳壁厚均匀。同时研究了该核壳结构的形成机理。电化学测试结果表明:中空的三氧化二锰核壳结构作为锂电池的电极材料,其初始放电比容量为1198mahg~(-1),在1ag~(-1)的电流密度下循环600圈后比容量为620mahg~(-1),高于其它文献报道的相似中空结构。此外材料还拥有不错的倍率性能。(2)通过简单的溶剂热方法合成了掺杂镍的碳酸锰实心微球和纯的碳酸锰微球。通过xrd、eds元素分布等相关的表征,证明了镍的成功掺杂。电化学测试结果表明:掺杂镍的碳酸锰是一种可逆性较好的赝电容机制电极材料。与纯碳酸锰相比,其内阻更小,电导率得到提升。在电流密度为1ag~(-1)时其比电容值为510fg~(-1),是同等测试条件下纯碳酸锰电容的两倍。在10ag~(-1)的电流密度下比容量仍可达到367fg~(-1),显示了较好的倍率性能。在5ag~(-1)的大电流密度下循环3000圈其容量保持率为85.8%。将掺杂镍的碳酸锰与活性炭材料组装成全电容,可成功点亮一组led灯,证明了该材料的实际应用潜力,同时也证明掺杂是一种能够提升金属碳酸物电极材料储能性能的有效手段。
[Abstract]:With climate change and the declining availability of fossil energy, modern societies are increasingly seeking to use sustainable and renewable energy sources such as wind and solar energy. In order to utilize these renewable energy more efficiently, the development of energy storage system becomes more and more important. Electrochemical energy storage devices have attracted much attention due to their high energy conversion efficiency. Typical electrochemical energy storage devices are lithium ion batteries and supercapacitors, which are widely used in portable electronics, hybrid electric vehicles and large industrial equipment, all of which require high energy density. The design and modification of electrode materials are the key factors of power density and long cycle life. Transition metal oxides not only have good lithium storage capacity but also have good pseudo-capacitance properties. Among them, manganese trioxide has high theoretical specific capacity (1018mA / h), friendly environment and abundant reserves, it is a promising electrode material for lithium battery, and manganese carbonate has simple preparation, low cost and good pseudo-capacitance performance. However, the conductivity of manganese trioxide is low, and the volume change caused by lithium deintercalation usually leads to poor performance and low cycle life of manganese trioxide. Similarly, manganese carbonate also has the problem of poor conductivity. Based on the above problems, it is very important to design and modify the materials reasonably for improving the electrochemical energy storage performance of the devices. The purpose of this paper is to provide a useful exploration for the development of electrochemical energy storage materials with excellent performance through simple structural design and modification of electrode materials. The main contents of this thesis are as follows: (1) the hollow manganese oxide core-shell structure was synthesized by template method. The characterization of transmission electron microscope shows that the synthesized manganese trioxide material is a self-assembled microsphere of uniform size nanoparticles, with an obvious hollow part between the core and the shell, and the outer shell wall thickness is uniform. The formation mechanism of the core-shell structure is also studied. The results of electrochemical measurements show that the hollow manganese oxide core-shell structure is used as electrode material for lithium batteries, its initial discharge specific capacity is 1198mah / g ~ (-1), and the specific capacity is 620mah / g ~ (-1), which is higher than the similar hollow structure reported in other literatures at current density of 600 cycles. In addition, the material also has good rate performance. 2) Nickel doped manganese carbonate solid microspheres and pure manganese carbonate microspheres were synthesized by a simple solvothermal method. The successful doping of nickel was proved by the related characterization of the distribution of xrdleds elements. The electrochemical results show that the nickel doped manganese carbonate is a good reversibility pseudo-capacitance mechanism electrode material. Compared with pure manganese carbonate, its internal resistance is smaller and its conductivity is improved. When the current density is 1 g / 1), the specific capacitance is 510fg ~ (-1), which is twice as high as the capacitance of pure manganese carbonate under the same test conditions. At the current density of 10g ~ (-1), the specific capacity can still reach 367fg ~ (-1), which shows good rate performance. The capacity retention rate of 3000 cycles at high current density is 85.8. When the nickel doped manganese carbonate and activated carbon material are assembled into full capacitors, a group of led lamps can be illuminated successfully, which proves the practical application potential of the material. It is also proved that doping is an effective means to improve the energy storage performance of metal carbonated electrode materials.
【学位授予单位】：太原理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TQ137.12;TM912;TM53

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