镍钴双金属化合物的赝电容特性研究

发布时间：2018-04-24 00:23

本文选题：超级电容器 + 多组元化合物　；参考：《华中科技大学》2014年博士论文

【摘要】：电化学电容器(又叫超级电容器)因其较高的功率密度、优良的循环稳定性、能够快速充放电等优点,在大功率设备、电动车、电子设备等领域广阔的应用前景而备受关注。目前所报导的各类电极活性材料中,金属化合物已经实现了较高的比容量及优良的循环稳定性,是最有希望实现高能量密度超级电容器的一类电极活性材料。本研究以镍钴基化合物为研究对象,通过改变镍与钴的成分比例及配位阴离子的种类构筑出一系列多元镍钻基化合物,如镍钻氢氧化物、镍钻氧化物、镍钻硫化物及镍钴硒化物,系统地研究了镍钻基化合物的超级电容性能。主要研究结果如下：提出了一种简易的混合溶剂热法,成功地用于制备不同镍钴组分的a相层状镍钴氢氧化物,并且可以引入基底用于制备镍钴氢氧化物阵列结构。a相镍钴氢氧化物作为超级电容器电极活性材料获得了比a相Ni(OH)2更高的比容量、倍率特性及循环稳定性,表明镍及钴离子配位化合形成氢氧化物可以明显提高其电化学活性并且改善a相结构的电化学稳定性。采用泡沫镍承载形成阵列结构可以进一步提高镍钴氢氧化物的比容量,并且实现了良好的循环稳定性。高温热分解a相镍钴氢氧化物及其泡沫镍承载的阵列样品,可以获得不同镍钴比例的镍钴氧化物及泡沫镍承载阵列结构样品。镍钴双金属氧化物样品表现出比CO3C4及NiO样品更高的比容量、倍率性能及循环稳定性。利用泡沫镍承载形成阵列结构可以进一步提高镍钴氧化物的比容量,并且实现了优良的循环稳定性。同时,采用一种简单的水解结合高温热处理方法制备出具有多孔结构的花状NiCo2O4纳米结构,NiCo2O4纳米结构具有比C0304和NiO高两个数量级以上的导电性,用作超级电容器电极活性材料时具有较高的比容量、优良的倍率特性及超长的循环稳定性。率先将镍钻双金属硫化物用作超级电容器电极活性材料,获得了优异的电化学性能。基于阴离子交换反应,提出一种简易的制备NiCo2S4海胆状纳米结构和泡沫镍承载的NiCo2S4纳米管阵列结构。NiCo2S4样品具有比相同形貌及结构的NiCo2O4更低的光学带隙宽度和更高的导电性,这有助于改善其用作电极活性材料时其电化学过程中的动力学特性。NiCo2S4海胆状纳米结构比相同形貌及结构的NiCo2O4及相同制备方法制备出的Co9S8和NiS具有更高的比容量及倍率性能。泡沫镍承载的NiCo2S4纳米管阵列结构在较高的单载量(6mg/cm2)下实现了超高的电极材料利用率,从而实现了超高的比容量。同时,采用多元醇法制备出不同镍钴比例的镍钻硫化物,率先研究了镍钴成分与镍钴双金属硫化物电化学性能的关系,镍钻双金属硫化物样品具有比相同条件制备出的单金属硫化物Co3S4和NiS更高的比容量及倍率性能,并且表现出比NiS更高的循环稳定性。采用一种简单的溶剂热法制备出CoSe、Co9Se8、NiSe和NiCo2Se4样品,率先将其用作电极活性材料获得了良好的超级电容性能。CoSe及Co9Se8样品具有超高的循环稳定性,分别经过7,000及10,000次循环后其比容量没发生任何衰减。NiSe最有较高的比容量,电流密度为1A/g时实现了高达808.45F/g的比容量。NiCo2Se4样品综合具有较高的比容量、倍率特性及循环稳定性,电流密度为1A/g时实现了高达535.7F/g的比容量,电流密度增加50倍后仍可保持最初的67.0%,并且经过7,000次充放电循环后其比容量仍可保持最初的94.92%。
[Abstract]:Electrochemical capacitors (also called supercapacitors) have attracted much attention because of their high power density, excellent cycling stability, fast charging and discharging, etc., which have been widely used in the fields of high power equipment, electric vehicles, electronic equipment and other fields. The specific capacity and excellent cyclic stability are the most promising type of electrode active materials for high energy density supercapacitors. In this study, a series of nickel drilling based compounds, such as nickel drill hydroxide and nickel drilling oxygen, were constructed by changing the composition ratio of nickel and cobalt and the types of coordination anions. The supercapacitor properties of nickel based compounds were systematically studied.
A simple mixed solvent thermal method was proposed, which was successfully used in the preparation of a phase layered nickel cobalt hydroxide with different nickel and cobalt components, and the substrate was introduced to prepare nickel cobalt hydroxide array structure.A phase nickel cobalt hydroxide as the supercapacitor electrode active material to obtain higher specific capacity than a phase Ni (OH) 2. The cyclic stability shows that the formation of hydroxides with nickel and cobalt complexes can obviously improve the electrochemical activity and improve the electrochemical stability of the a phase structure. The specific capacity of Ni Co hydroxides can be further improved by the formation of an array structure with nickel foam, and a good cyclic stability is achieved.
The nickel cobalt oxide and nickel foam bearing array structure samples with different nickel and cobalt ratio can be obtained by thermal decomposition of a phase nickel cobalt hydroxide and the array samples loaded with nickel foam. The nickel cobalt bimetallic oxide sample shows higher specific capacity, multiplying performance and cyclic stability than CO3C4 and NiO samples. The column structure can further improve the specific capacity of nickel cobalt oxide and achieve excellent cyclic stability. At the same time, a simple NiCo2O4 nanostructure with porous structure is prepared by a simple hydrolysis combined with high temperature heat treatment. The NiCo2O4 nanostructure has more than two orders of magnitude higher than C0304 and NiO. The electrode material of super capacitor has higher specific capacity, excellent magnification characteristic and super long cycle stability.
The nickel drilled bimetallic sulfide was first used as a supercapacitor electrode active material and excellent electrochemical performance was obtained. Based on anionic exchange reaction, a simple preparation of NiCo2S4 sea urchin like nanostructures and NiCo2S4 nanotube arrays loaded with nickel foam had a lower NiCo2O4 than the same morphology and structure. The width of the optical band gap and the higher conductivity are helpful to improve the kinetic characteristics of its electrochemical process as the active material of the electrode..NiCo2S4 sea urchin like nanostructures have higher specific capacity and multiple ratio properties than the same morphology and structure of NiCo2O4 and the same preparation method of Co9S8 and NiS. NiCo 2S4 nanotube arrays have achieved ultra-high utilization of electrode materials at a high single load (6mg/cm2), thus achieving super high specific capacity. At the same time, nickel cobalt sulfide with different nickel and cobalt ratios was prepared by polyol method. The relationship between nickel and cobalt composition and the electrochemical properties of nickel cobalt sulfide sulfide was first studied. The samples have higher specific capacity and multiple rate properties than the single metal sulfide Co3S4 and NiS prepared from the same conditions, and exhibit higher cyclic stability than NiS.
CoSe, Co9Se8, NiSe and NiCo2Se4 samples were prepared by a simple solvothermal method. They were first used as electrode active materials to obtain excellent supercapacitor performance,.CoSe and Co9Se8 samples have super high cyclic stability. After 7000 and 10000 cycles, the specific capacity of.NiSe has not occurred any attenuation of.NiSe. When the current density is 1A/g, the.NiCo2Se4 sample with a specific capacity of up to 808.45F/g has a higher specific capacity, multiple rate characteristic and cyclic stability. When the current density is 1A/g, the specific capacity is up to 535.7F/g, and the current density increases 50 times, and it can still maintain the initial 67%, and the specific capacity after the 7000 charge discharge cycle. It is still possible to keep the original 94.92%.

【学位授予单位】：华中科技大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：TM53

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