硫化镍复合材料的制备及其在超级电容器中的应用
发布时间：2018-08-19 19:26
【摘要】：在当今能源短缺和环境污染的背景下,开发一种新型的绿色储能装置成为重要的解决之道。超级电容器作为一种介于电池与传统电容器间的新型能量储存和转换器件,具有功率密度高、充放电效率高、循环稳定性好、绿色环保等特点,因而被广泛应用于多种领域。然而较低的能量密度成为制约其发展的重要因素。根据能量密度公式E=1/2CV2知,可以通过提高电极材料电容量(C)和拓宽工作电压(V)来实现能量密度的提高。通过设计匹配两种不同储能方式的电极组装成非对称电容器来提高能量密度成为研究热点。拥有多种化学计量比的硫化镍价格低廉、来源广泛、比电容高,在高性能超级电容器方面有良好的应用前景。本文以多孔泡沫镍为基底,成功制备比电容高、能量密度高、循环稳定性好的硫化镍及其复合纳米材料,并与活性炭(AC)构成非对称电容器。通过相关测试,表征合成材料的形貌与结构、评估其电化学性能。主要研究内容如下:(1)采用简单便捷的连续离子层吸附法(SILAR),常温下,在泡沫镍集流体上直接合成了纯度较高的片层状NiS。立体片层结构使得材料比表面积增加,活性材料利用显著率提高,在三电极测试条件下,NiS表现出良好的赝电容特性,1 A g-1的电流密度下,其比电容高达1678 F g-1。组装成非对称电容器后实现高能量密度42.3 Wh kg-1,5000次循环充放电后容量保持率为83.0%。表明合成材料具有良好的电化学性能和循环稳定性。与以往SILAR法得到无定型薄膜相比,该法一步制备金属硫化物片层具有一定创新性。(2)通过两步合成法实现具有核壳结构Co_3O_4@Ni_3S_2三维纳米线阵列的构建,以多孔泡沫镍为基底,水热法合成Co_3O_4纳米线以及电沉积法合成Ni_3S_2超薄纳米片,共同组成有序的分级结构纳米复合材料。与单一的Co_3O_4和Ni_3S_2电极材料相比,该复合材料表现出更加优异的电化学性能。在三电极体系中,1 A g-1的电流密度下,其比电容高达1710 F g-1,循环充放电1000次后容量保持率为88.5%。组装成非对称电容器后,在1 A g-1的电流密度下展现出126.6 F g-1的高比电容和44.9 Wh kg-1的高能量密度。本课题核壳纳米线阵列的设计可有效缩短离子扩散和电子传输途径,通过复合材料的协同作用,从而显著提高性能。(3)通过两步合成路线制备具有三维分级结构的CoAl-LDH@Ni_3S_2纳米片阵列。利用水热合法在泡沫镍基底上垂直生长钴铝层状双氢氧化物(CoAl-LDH)纳米片阵列。通过控制电沉积条件,在CoAl-LDH片层表面包裹Ni_3S_2超薄纳米片。本课题新颖的形貌设计使得合成的复合材料具有优良的电化学性能。在三电极体系中,1 A g-1的电流密度下,比电容高达1904 F g-1。以CoAl-LDH为正极,活性炭为负极,组装成非对称电容器,工作电压可拓宽至1.6 V,5000次循环充放电后容量保持率仍有84.2%。研究表明,形成的特殊“片-网”结构可显著增加电极材料与电解质溶液离子的接触机率,维持机械稳定性从而实现储能性能的增强。
[Abstract]:Under the background of energy shortage and environmental pollution, developing a new type of green energy storage device becomes an important solution. As a new type of energy storage and conversion device between battery and traditional capacitor, supercapacitor has the characteristics of high power density, high charging and discharging efficiency, good cycle stability and green environmental protection. However, low energy density has become an important factor restricting its development. According to the energy density formula E=1/2CV2, the increase of energy density can be achieved by increasing the capacitance of electrode material (C) and broadening the working voltage (V). Nickel sulfide with various stoichiometric ratios has low price, wide source, high specific capacitance and good application prospect in high performance supercapacitors. In this paper, nickel sulfide with high specific capacitance, high energy density and good cycle stability was successfully prepared on porous nickel foam substrate. The main research contents are as follows: (1) A simple and convenient continuous ion layer adsorption (SILAR) method was used to synthesize lamellar N with high purity on nickel foam collector at room temperature. IS. Three-dimensional lamellar structure makes the specific surface area of the material increase and the utilization rate of the active material increase significantly. Under the condition of three-electrode test, NiS exhibits good pseudo-capacitance characteristics. At the current density of 1 A g-1, the specific capacitance of NiS is as high as 1678 F g-1. The mass retention rate is 83.0%. The results show that the synthesized materials have good electrochemical properties and cyclic stability. Compared with the amorphous films prepared by SILAR method, the one-step preparation of metal sulfide lamellae is innovative. (2) The core-shell structure of Co_3O_4@Ni_3S_2 three-dimensional nanowire arrays was fabricated by two-step synthesis method, and the porous films were obtained. Co_3O_4 nanowires were synthesized by hydrothermal method and Ni_3S_2 ultrathin nanosheets were synthesized by electrodeposition. The ordered hierarchical nanocomposites were prepared by hydrothermal method and electrodeposition. Compared with single Co_3O_4 and Ni_3S_2 electrode materials, the composites exhibited more excellent electrochemical properties. The specific capacitance is as high as 1710 F g-1, and the capacity retention rate is 88.5% after 1000 cycles of charging and discharging. The asymmetric capacitors exhibit high specific capacitance of 126.6 F g-1 and high energy density of 44.9 Wh kg-1 at the current density of 1 Ag-1. The design of core-shell nanowire arrays can effectively shorten the ion diffusion and electron transmission paths. (3) CoAl-LDH@Ni_3S_2 nanosheet arrays with three-dimensional hierarchical structure were fabricated by a two-step synthesis route. The cobalt-aluminum layered double hydroxide (CoAl-LDH) nanosheet arrays were grown vertically on nickel foam substrates by hydrothermal method. In the three-electrode system, at the current density of 1 A g-1, the specific capacitance is as high as 1904 F g-1. The asymmetric capacitor is assembled with CoAl-LDH as the positive electrode and activated carbon as the negative electrode. The working voltage can be extended to 1.6 V, 5000. The results show that the special "sheet-net" structure can significantly increase the contact probability between electrode materials and electrolyte solution ions, maintain the mechanical stability and enhance the energy storage performance.
【学位授予单位】：华侨大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TB33;TM53
，
本文编号：2192602
[Abstract]:Under the background of energy shortage and environmental pollution, developing a new type of green energy storage device becomes an important solution. As a new type of energy storage and conversion device between battery and traditional capacitor, supercapacitor has the characteristics of high power density, high charging and discharging efficiency, good cycle stability and green environmental protection. However, low energy density has become an important factor restricting its development. According to the energy density formula E=1/2CV2, the increase of energy density can be achieved by increasing the capacitance of electrode material (C) and broadening the working voltage (V). Nickel sulfide with various stoichiometric ratios has low price, wide source, high specific capacitance and good application prospect in high performance supercapacitors. In this paper, nickel sulfide with high specific capacitance, high energy density and good cycle stability was successfully prepared on porous nickel foam substrate. The main research contents are as follows: (1) A simple and convenient continuous ion layer adsorption (SILAR) method was used to synthesize lamellar N with high purity on nickel foam collector at room temperature. IS. Three-dimensional lamellar structure makes the specific surface area of the material increase and the utilization rate of the active material increase significantly. Under the condition of three-electrode test, NiS exhibits good pseudo-capacitance characteristics. At the current density of 1 A g-1, the specific capacitance of NiS is as high as 1678 F g-1. The mass retention rate is 83.0%. The results show that the synthesized materials have good electrochemical properties and cyclic stability. Compared with the amorphous films prepared by SILAR method, the one-step preparation of metal sulfide lamellae is innovative. (2) The core-shell structure of Co_3O_4@Ni_3S_2 three-dimensional nanowire arrays was fabricated by two-step synthesis method, and the porous films were obtained. Co_3O_4 nanowires were synthesized by hydrothermal method and Ni_3S_2 ultrathin nanosheets were synthesized by electrodeposition. The ordered hierarchical nanocomposites were prepared by hydrothermal method and electrodeposition. Compared with single Co_3O_4 and Ni_3S_2 electrode materials, the composites exhibited more excellent electrochemical properties. The specific capacitance is as high as 1710 F g-1, and the capacity retention rate is 88.5% after 1000 cycles of charging and discharging. The asymmetric capacitors exhibit high specific capacitance of 126.6 F g-1 and high energy density of 44.9 Wh kg-1 at the current density of 1 Ag-1. The design of core-shell nanowire arrays can effectively shorten the ion diffusion and electron transmission paths. (3) CoAl-LDH@Ni_3S_2 nanosheet arrays with three-dimensional hierarchical structure were fabricated by a two-step synthesis route. The cobalt-aluminum layered double hydroxide (CoAl-LDH) nanosheet arrays were grown vertically on nickel foam substrates by hydrothermal method. In the three-electrode system, at the current density of 1 A g-1, the specific capacitance is as high as 1904 F g-1. The asymmetric capacitor is assembled with CoAl-LDH as the positive electrode and activated carbon as the negative electrode. The working voltage can be extended to 1.6 V, 5000. The results show that the special "sheet-net" structure can significantly increase the contact probability between electrode materials and electrolyte solution ions, maintain the mechanical stability and enhance the energy storage performance.
【学位授予单位】：华侨大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TB33;TM53
，
本文编号：2192602
本文链接：https://www.wllwen.com/kejilunwen/cailiaohuaxuelunwen/2192602.html
