【作者】 邓晶晶；

【导师】 邓建成；

【作者基本信息】 湘潭大学 ， 应用化学， 2009， 硕士

【摘要】 超级电容器是一种新型储能装置,具有瞬间释放大电流、能量密度高、充放电效率高、循环寿命长等优点,可广泛应用于电动汽车的启动和刹车系统、移动通讯、信息技术、航空航天和国防科技等领域。氧化镍作为超级电容器电极材料,具有典型的法拉第准电容性能,并且资源丰富、价格低廉,因此成为研究的热点。本文研究了纳米氧化镍及其复合材料的制备方法,对产品的微观结构和形貌进行了分析表证,并对其电化学性能进行了系统的研究。主要内容如下:(1)采用配位均匀沉淀法由不同的路径成功地制备出了颗粒状和针形两种不同形貌的纳米氧化镍。研究结果表明:颗粒状氧化镍比针形氧化镍具有更小的欧姆电阻、更高的比电容。在6 mol/L KOH电解液中,前者的比电容为203.6 F/g,约为后者的两倍。氧化镍电极材料的电化学性能受到热处理温度、电解液浓度、CV扫速以及恒流充放电电流密度的影响。(2)通过水热法以β-环糊精为模板剂制备了纳米氧化镍,产品呈球形颗粒状,粒径约为5～8 nm。电化学测试结果表明,最佳水热反应条件为140℃下反应24 h。以β-环糊精为模板剂来制备材料,降低了产品的团聚程度,提高了产品的分散性,降低了产品电极的欧姆电阻,提高了电极的比电容。最佳条件下合成的氧化镍比电容为196.8 F/g,比非环糊精体系提高了59.6%,电极内在电阻为0.9 ?,比非环糊精体系降低了35.7%。(3)采用配位均匀共沉淀法制备了纳米镍钴复合氧化物,不同钴含量对材料的电化学电容性能有较大影响,当钴摩尔分数约为65%为时,复合材料的电化学性能最好,该比例的复合物具有更小的欧姆电阻(1.0 ?)、更高的比电容(286.9 F/g)、更适合在大电流下充放电。SEM、TEM测试结果还显示,掺钴之后,氧化镍的微观形貌发生了改变,由球形纳米颗粒的堆积转变成纳米线的堆积,结构更为蓬松,且具有丰富的孔结构,比表面积为192.176 m2/g(较之纯氧化镍提高了19.4%),这种结构使得复合材料更容易被电解液浸润,扩大了电化学反应的有效区域。另外,复合材料电极的内在电阻也由纯氧化镍的1.8 ?降为1.0 ?,电化学电容性能显著提高。该复合材料具有良好的循环稳定性。(4)以镍钴复合氧化物为正极,以活性炭为负极,组装了小型的混合电容器,实验结果表明,当正负极的质量比为1:2.7时,该混合电容器的质量比电容最大,为56.4 F/g。与对称电容器相比,该混合电容器的电位窗口提高为1.2 V,能量密度明显提高,并且具有较好的功率特性和循环稳定性。更多还原

【Abstract】 Supercapacitors have been recognized as unique energy storage devices which can release large discharge current instantly, have high energy density and long cycle life. Based on the above, the promising application of supercapacitors in the fields such as mobile telecommunication, information technology, consumer electronics, electric vehicle, aviation, and military force, have been attracting more and more attention throughout the world. NiO is a typical electrode material for supercapacitor due to its typical faradaic pseudocapacitance behavior and low price. The study focuses on the preparation and characteristics of nano-scale NiO and composite materials for supercapacitor. The microstructures, morphologies and electrochemical properties of these materials were investigated. The main content is as follows:(1) Sphere-like and needle-like nano-scale NiO were successful synthesized by a new method—coordination homogeneous precipitation method. The results show that sphere-like NiO has lower resistance and higher specific capacitance. The sphere-like NiO can provide a specific capacitance of～203.6 F/g, which is nearly 2 times greater than that of needle-like NiO. Additionally, the electrochemical properties of NiO ware affected by calcination temperature, electrolyte concentration, scan rate of cyclic voltammetry and charge-discharge current density.(2) Hydrothermal synthesis withβ-cyclodextrin(β-CD) as template reagent has been introduced to fabricate nano-scale NiO. The major morphology of as-prepared NiO is sphere-like particles with a dimension of 5～8 nm. The results of electrochemical tests indicate that the optimal react condition is 140℃for 24 h. , The as-prepared NiO usingβ-CD exhibits slighter agglomeration, lower internal resistance and higher specific capactance. A specific capacitance approximate to 196.8 F/g could be achieved, which increase 59.6% compared to that of product without usingβ-CD. The internal resistance is 0.9 ? which decrease 35.7%.(3) A series of Ni-Co oxide nano-composites were prepared by thermal decomposition of the precursors obtained via coordination homogeneous co-precipitation method. The electrochemical properties of Ni-Co oxide electrodes are greatly affected by the molar ratio of Co. Results indicate that Ni-Co oxide with nCo=65% shows not only lower resistance (1.0 ?), higher specific capacitance (286.9 F/g), but also better charge-discharge properties at high current density. SEM and TEM results show that the microstructure of NiO changes from nanospheres to nanowires which aggregate to form clusters with a porous structure after the addition of cobalt element. The composite has abundant pore structure, and the surface area is 192.176 m2/g, which is 18.6% enhanced compare with pure NiO. The fluey structure of the composite makes electrolyte easily soaks into the inner surface of material, which leads to larger effective surface areas. Additionaly, the internal resistance of composite materials is 1.0 ?, while the counterpart of pure NiO is 1.8 ?. The electrochemical capacitive properties of composite materials are enhanced remarkably. The as-prepared composite electrode has good charge–discharge cycle stability.(4) Hybride supercapacitor was assembled, Ni-Co oxide composite and active carbon were applied to the positive and negative electrodes respectively. The effect of the mass ratio of positive electrode and negative electrode was discussed. It is proved that the maximum specific capacitance of the hybride supercapacitor reaches 56.4 F/g under the mass ratio of 1:2.7. The maximum operational voltage of the capacitor was 1.2 V, which is improved effectively,and the energy density increased obviously.It also has good power density and cycle stability.更多还原