镍—钴氢氧化物电极材料的制备及其电化学性能的研究

发布时间：2018-03-19 07:25

  本文选题：超级电容器　切入点：电极材料　出处：《吉林大学》2016年硕士论文　论文类型：学位论文

【摘要】：在众多活性电极材料中,氢氧化镍以其低价无毒比容量高的特性,成为了超级电容器电极材料的理想选择。而目前在对氢氧化镍电极材料的研究主要集中在了晶体相而很少有人关注非晶或者弱结晶状态的Ni(OH)2以及他们的复合物。本文通过不同的实验方法制备出非晶氢氧化镍、非晶镍-钴氢氧化物复合材料以及弱结晶状态下的镍基氢氧化物、镍-钴复合氢氧化物。通过SEM、TEM、XRD、XPS等检测方法对材料的微观形貌和结构特征进行分析。利用循环伏安法、恒定流充放电法、交流阻抗法等电化学分析方法对制备的材料进行电化学性能分析。本文采用一种绿色无毒的电化学方法制备了非晶Ni(OH)2、非晶镍-钴复合氢氧化物。钴的加入很好的改善了非晶氢氧化镍的电化学性能。钴的加入使非晶氢氧化镍原本纳米微球的均匀分布状态变为更多的小纳米微球均匀的分布在样品表面。其一,在提高电导率的同时改善了材料利用率;其二,由于钴的加入很好的抑制了γ-Ni OOH的形成,优化了原有材料的稳定性;第三,改变了材料氧化还原电位,对充放电效率也有改善。钴的加入使非晶氢氧化镍材料的比容量由1692 F·g-1提高到1769 F·g-1(5 m V·s-1),3000圈后循环性能由73%提高到83%。采用水热法制备了弱结晶状态的Ni(OH)2,以及不同比例镍-钴氢氧化物。我们发现水热法制备的镍基氢氧化物在90℃反应6 h可以获得最佳的性能,所有材料微观形貌都是表面带有褶皱的薄片结构。随着钴含量的增多复合材料的片层厚度先减小后增大,在最薄时为2 nm左右,褶皱的分布也更加均匀。说明钴的加入对材料的结构分布有一定的影响。在钴含量为7%,电流密度为1 A·g-1时,材料的比电容由纯氢氧化镍的1145 F·g-1增加到了1852 F·g-1。1000圈后的保持率也由52.7%升高到91%。此外,本文还分别以绿色环保电化学方法制备的非晶Ni(OH)2、非晶镍-钴氢氧化物材料作为正极材料,活性炭作为负极材料制备纽扣式非对称超级电容器件,所用电解液为3 M KOH溶液,在0.0-1.3V的电势窗口内进行测试,表现出了良好的比电容及循环性能,最高比电容为106 F·g-1,最高能量密度为25 Wh kg-1。在功率密度为1.56 k W kg-1时能量密度仍能保持在19.1 Wh kg-1。性能优于很多已经报道的以碳基材料与氢氧化镍材料组装的非对称电容器。此外镍-钴氢氧化物复合材料比纯氢氧化镍材料制备的电容器件拥有更好的循环性能,循环3000圈后仍有81%的容量保持率。
[Abstract]:Among many active electrode materials, nickel hydroxide is characterized by its low price and high specific capacity. It has become an ideal choice of electrode materials for supercapacitors, but the current research on nickel hydroxide electrode materials is mainly focused on the crystalline phase and few people pay attention to amorphous or weakly crystallized Ni(OH)2 and their complexes. In this paper, amorphous nickel hydroxide was prepared by different experimental methods. Amorphous nickel-cobalt hydroxide composites and Ni-base hydroxides and nickel-cobalt composite hydroxides in weakly crystallized state. The microstructure and structural characteristics of the materials were analyzed by means of SEMMOTEMX XRDX XPS, and cyclic voltammetry was used. Constant current charge-discharge method, The electrochemical properties of the prepared materials were analyzed by electrochemical analysis methods such as AC impedance method. In this paper, a green and non-toxic electrochemical method was used to prepare amorphous NiOH2, amorphous nickel-cobalt complex hydroxides. The addition of cobalt is very good. The electrochemical performance of amorphous nickel hydroxide is improved. The addition of cobalt makes the uniform distribution of amorphous nickel hydroxide nanoparticles into more and more small nanometer-sized microspheres uniformly distributed on the surface of the sample. The conductivity is increased and the material utilization rate is improved. Secondly, the formation of 纬 -Ni OOH is restrained and the stability of the original material is optimized because of the addition of cobalt. Thirdly, the redox potential of the material is changed. The specific capacity of amorphous nickel hydroxide material was increased from 1692F 路g-1 to 1769F 路g -1 5mV 路s-1C ~ (3 000) from 73% to 833. The weakly crystallized NiOH2 was prepared by hydrothermal method, and the specific ratio of NiOH2 was increased to 833F 路g ~ (-1) by the addition of cobalt, and the specific capacity of amorphous nickel hydroxide was increased from 1692 F 路g ~ (-1) to 1769 F 路g ~ (-1) ~ (-1) from 73% to 83. For example, Ni-Co hydroxide. We found that the best performance of nickel-base hydroxide prepared by hydrothermal method can be obtained at 90 鈩，

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