离子掺杂与纳米导电聚合物复合对纳米氧化锰电容性能影响的研究

发布时间：2018-05-01 18:25

  本文选题：超级电容器 + 纳米二氧化锰　； 参考：《济南大学》2017年硕士论文

【摘要】：超级电容器因具有高功率密度和长期循环稳定性,已经成为极具吸引力的电化学存储系统之一。由于理论比容量高,成本低,储量丰富和环境友好性等特点,氧化锰(MnO_2)受到越来越多的关注。本文首先采用水热法制备了δ-MnO_2,α-MnO_2,γ-MnO_2和β-MnO_2四种不同晶体结构的纳米MnO_2,探究了反应时间和反应温度对纳米MnO_2晶体结构和形貌的影响,并且对其进行了电化学性能的测试,结果表明纳米δ-MnO_2的电化学性能最佳,在此基础上,通过金属离子掺杂和导电聚合物复合两种方法对δ-MnO_2进行了改性。具体研究内容及主要结果如下:1.以KMnO4为原料,在酸性条件下,采用一步水热法,分别在100°C、140°C、180°C下反应1 h、3 h、6 h、12 h,得到了不同形貌的纳米δ-MnO_2和α-MnO_2。通过对所得样品的表征及电化学性能测试,实验结果及分析表明:随着反应温度的升高和反应时间的延长,所得到的MnO_2首先生成片状的δ-MnO_2,逐渐长成由纳米片组成的花球状δ-MnO_2,最后纳米片发生卷曲为纳米管状的α-MnO_2。在这个过程中MnO_2的晶体结构由2D层状转变为[2×2]的隧道结构。实验所得样品的颜色也因为晶体结构的转变由黑色逐渐变为深褐色。说明反应温度和反应时间是影响MnO_2的晶体结构和形貌的重要因素。其中,在反应温度为100℃,反应时间为1 h的条件下得到的δ-MnO_2比电容高达196.8 F g-1。随着反应温度是的升高和反应时间的延长,所得样品的比电容逐渐减小。γ-MnO_2和β-MnO_2的最高比电容分别为117.2 F g-1和37.6 F g-1。分析比较可得,纳米δ-MnO_2的比容量明显优于其它晶型的MnO_2。2.在上述研究基础上,选择δ-MnO_2作为金属离子掺杂的对象,以KMnO4为母盐,泡沫镍(Ni Foam,简称NF)为载体,通过简单的水热法分别合成了Co~(2+),Bi~(3+)和Fe~(3+)离子掺杂的δ-MnO_2/NF复合物,δ-MnO_2的电化学性能得到了很大的提高。在2 mV s-1的扫描速率下,掺杂2at.%Co~(2+),2at.%Bi~(3+),4at.%Fe~(3+)得到的δ-MnO_2/NF的比电容分别是506.8 F g-1、365.6 F g-1、376.1 F g-1,远高于未掺杂δ-MnO_2/NF的198.5 F g-1;其阻抗性能也得到了很大的改善。3.以苯胺单体为还原剂,以过硫酸铵为氧化剂,在冰浴条件下制备了海参状纳米棒聚苯胺(PANI)。以纳米PANI为基底,以KMnO4为氧化剂,采用原位生长法在PANI表面生长纳米片状的δ-MnO_2,得到了纳米δ-MnO_2@PANI复合物。通过对复合材料的表征和电化学性能的测试,结果表明:纳米PANI对KMnO4表现出良好的还原性能,使得纳米尺度的δ-MnO_2成功负载在PANI纳米棒的表面。纳米δ-MnO_2@PANI复合材料在0.5A g-1的电流密度下,比电容达到524.2 F g-1,远远大于单纯的PANI和δ-MnO_2的比电容。反过来,以纳米MnO_2为基底,在其表面生长PANI,在2 mV s-1的速率下,所得纳米PANI@δ-MnO_2复合物的比电容为261.8 F g-1,氧化锰的电容性能没有得到明显改善。
[Abstract]:Supercapacitors have become one of the most attractive electrochemical storage systems due to their high power density and long-term cycle stability. Due to the characteristics of high theoretical capacity, low cost, abundant reserves and environmental friendliness, manganese oxide (MNO _ 2) has attracted more and more attention. In this paper, four kinds of nanocrystals of 未 -MnO _ 2, 伪 -MnO _ 2, 纬 -MnO _ 2 and 尾 -MnO _ 2 were prepared by hydrothermal method. The effects of reaction time and reaction temperature on the structure and morphology of nanocrystalline MnO_2 were investigated, and their electrochemical properties were tested. The results show that 未 -MnO _ 2 has the best electrochemical performance. On the basis of this, 未 -MnO _ 2 is modified by metal ion doping and conducting polymer composite. The specific research contents and main results are as follows: 1. Using KMnO4 as raw material and under acidic conditions, the nanosized 未 -MnO _ 2 and 伪 -MnO _ 2 were obtained by one-step hydrothermal reaction at 100 掳C ~ (10) C ~ (140) C ~ (180 掳C) for 1 h ~ 3 h ~ 6 h ~ (-1) ~ (-1) ~ (-1) ~ (-1) h ~ (-1) ~ 12 h ~ (-1) respectively. Through the characterization and electrochemical performance test of the samples, the experimental results and analysis showed that: with the increase of reaction temperature and the prolongation of reaction time, The obtained MnO_2 first produces a flake 未 -MnO _ 2, and gradually grows into a spherical 未 -MnO _ (2) structure made up of nanochips. Finally, the nanochips are curled into nanotube 伪 -MnO _ (2) _ s _ (2). In this process, the crystal structure of MnO_2 is changed from 2D layer to [2 脳 2] tunnel structure. The color of the sample was changed from black to dark brown. The results show that the reaction temperature and reaction time are important factors affecting the crystal structure and morphology of MnO_2. The specific capacitance of 未 -MnO _ 2 is up to 196.8 F g ~ (-1) when the reaction temperature is 100 鈩，

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