基于三维多孔镍沉积二氧化锰电极电化学特性的研究
发布时间：2019-05-07 09:24
【摘要】：面对资源急剧的消耗,人类亟待在能源利用与环境污染间寻得平衡,新型储能材料成为世界各国的研究重点。电化学电容器作为新型储能材料,能量密度大、充放电速率高,优势明显。其中,二氧化锰具有较高的理论比容量(SC)1370 F g-1,成本低廉对环境友好,常作为电化学电容器电极材料。但是,二氧化锰导电性差,高比容量只存在于二氧化锰膜层较薄的情况下,因而制备具有大比表面和超薄膜层的二氧化锰是获得高比容量的有效途径。本文在三维多孔镍上阳极电沉积二氧化锰,并改变沉积参数控制其微观形貌的变化,深入讨论了二氧化锰/多孔镍电极的沉积参数、形貌和电化学性能之间的关系,探索了制备高性能电化学电容器电极材料的有效途径。本文首先通过恒电流法沉积二氧化锰,分别改变沉积电流密度和沉积时间,并对多孔镍沉积二氧化锰的形貌进行分析,实验结果表明:随着沉积电流密度增大,多孔镍镍柱上沉积的氧化锰形态由纤维状向均匀包裹镍柱的连续涂层转变。电极性能与沉积电流密度和循环伏安扫描速率的大小以及沉积物形貌关系密切。沉积电流密度为10 m A cm-2、沉积时间为10 min的多孔镍二氧化锰电极面积比电容值在1 m V s-1的扫描速率下达到0.9 F cm-2,其体积比电容值为200 F cm-3;在扫描速率为10 m V s-1时,面积比电容在经过1000个循环后仅仅由0.528 F cm-2下降为0.525 F cm-2,具有良好的循环稳定性。随后,本论文在恒定电量条件下恒压沉积二氧化锰,改变沉积电压和沉积温度,研究沉积参数对二氧化锰微观形貌的影响,并讨论了形貌与二氧化锰/多孔镍复合电极电化学性能的关系。实验结果表明:随着沉积电压的下降,晶粒成核速率随之降低,氧化锰沉积物形貌由纳米颗粒转化为纳米纤维;而随着沉积温度的上升,晶粒生长速率逐渐超越成核速率,氧化锰沉积物形貌出现类似的变化规律,由纳米颗粒转变为纳米纤维簇。其中,纳米片(花瓣)状,纳米串珠,纳米颗粒/柱分别为颗粒转变为纤维的过渡态,其形貌是由成核速率的大小以及晶体生长过程中生长速率和成核速率的关系共同作用的结果。同等电量(Q=1.8 C)沉积下,面积比电容值最大时的沉积条件为:沉积温度0°C,沉积电压0.75 V,此时样品面积比电容值为0.311 F cm-2(扫描速率10 m V s-1),形貌为纳米串珠状。
[Abstract]:In the face of the rapid consumption of resources, human beings need to find a balance between energy use and environmental pollution, and new energy storage materials have become the focus of research all over the world. As a new type of energy storage material, electrochemical capacitor has high energy density, high charge-discharge rate and obvious advantages. Manganese dioxide (MNO _ 2) has high theoretical specific capacity (SC) 1370 F / g ~ (1), low cost and environmental friendliness, and is often used as electrode material for electrochemical capacitors. However, the conductivity of manganese dioxide is poor, and the high specific capacity only exists in the case of thin manganese dioxide film. Therefore, the preparation of manganese dioxide with large specific surface area and ultra-thin film is an effective way to obtain high specific capacity. In this paper, manganese dioxide was electrodeposited on three-dimensional porous nickel anode, and the change of micro-morphology was controlled by changing the deposition parameters. The relationship between deposition parameters, morphology and electrochemical properties of manganese dioxide / porous nickel electrode was discussed in depth. An effective way to fabricate electrode materials for electrochemical capacitors with high performance has been explored. In this paper, firstly, manganese dioxide was deposited by constant current method, the deposition current density and deposition time were changed, and the morphology of manganese dioxide deposited by porous nickel was analyzed. The experimental results show that: with the increase of deposition current density, The morphology of manganese oxide deposited on porous Ni-Ni column changed from fiber-like to continuous coating coated uniformly. The electrode performance is closely related to the deposition current density, cyclic voltammetry scanning rate and sediment morphology. When the deposition current density is 10 Ma cm-2, and the deposition time is 10 min, the specific capacitance of porous nickel manganese dioxide electrode reaches 0.9 F / cm-2, at the scanning rate of 1 MV / s / 1, and the volume specific capacitance is 200 F / cm-3;. At a scanning rate of 10 MV 路s ~ (- 1), the area specific capacitance only decreases from 0.528 F cm-2 to 0.525 F / cm-2, after 1000 cycles and has good cycling stability. In this paper, the deposition voltage and temperature of manganese dioxide were changed, and the effect of deposition parameters on the microstructure of manganese dioxide was studied. The relationship between morphology and electrochemical performance of manganese dioxide / porous nickel composite electrode was also discussed. The experimental results show that with the decrease of deposition voltage, the nucleation rate of grains decreases, and the morphology of manganese oxide deposits is transformed from nano-particles to nano-fibers. With the increase of deposition temperature, the grain growth rate gradually exceeded the nucleation rate, and the morphology of manganese oxide deposits changed from nano-particles to nano-fiber clusters. Among them, nano-slice (petal)-like, nano-bead, nano-particle / column is the transition state of the particle to the fiber, respectively. The morphology is affected by the size of nucleation rate and the relationship between growth rate and nucleation rate during crystal growth. The deposition conditions are as follows: deposition temperature 0 掳C, deposition voltage 0.75 V, sample area specific capacitance 0.311 F / cm-2 (scanning rate 10 MV / s / 1), when the area specific capacitance is maximum at the same amount of electricity (Q = 1.8 C), the deposition temperature is 0 掳C, the deposition voltage is 0.75 V, and the specific capacitance of the sample is 0.311 F / V. The morphology is nano-string beads.
【学位授予单位】：华南理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TM53
本文编号：2470966
[Abstract]:In the face of the rapid consumption of resources, human beings need to find a balance between energy use and environmental pollution, and new energy storage materials have become the focus of research all over the world. As a new type of energy storage material, electrochemical capacitor has high energy density, high charge-discharge rate and obvious advantages. Manganese dioxide (MNO _ 2) has high theoretical specific capacity (SC) 1370 F / g ~ (1), low cost and environmental friendliness, and is often used as electrode material for electrochemical capacitors. However, the conductivity of manganese dioxide is poor, and the high specific capacity only exists in the case of thin manganese dioxide film. Therefore, the preparation of manganese dioxide with large specific surface area and ultra-thin film is an effective way to obtain high specific capacity. In this paper, manganese dioxide was electrodeposited on three-dimensional porous nickel anode, and the change of micro-morphology was controlled by changing the deposition parameters. The relationship between deposition parameters, morphology and electrochemical properties of manganese dioxide / porous nickel electrode was discussed in depth. An effective way to fabricate electrode materials for electrochemical capacitors with high performance has been explored. In this paper, firstly, manganese dioxide was deposited by constant current method, the deposition current density and deposition time were changed, and the morphology of manganese dioxide deposited by porous nickel was analyzed. The experimental results show that: with the increase of deposition current density, The morphology of manganese oxide deposited on porous Ni-Ni column changed from fiber-like to continuous coating coated uniformly. The electrode performance is closely related to the deposition current density, cyclic voltammetry scanning rate and sediment morphology. When the deposition current density is 10 Ma cm-2, and the deposition time is 10 min, the specific capacitance of porous nickel manganese dioxide electrode reaches 0.9 F / cm-2, at the scanning rate of 1 MV / s / 1, and the volume specific capacitance is 200 F / cm-3;. At a scanning rate of 10 MV 路s ~ (- 1), the area specific capacitance only decreases from 0.528 F cm-2 to 0.525 F / cm-2, after 1000 cycles and has good cycling stability. In this paper, the deposition voltage and temperature of manganese dioxide were changed, and the effect of deposition parameters on the microstructure of manganese dioxide was studied. The relationship between morphology and electrochemical performance of manganese dioxide / porous nickel composite electrode was also discussed. The experimental results show that with the decrease of deposition voltage, the nucleation rate of grains decreases, and the morphology of manganese oxide deposits is transformed from nano-particles to nano-fibers. With the increase of deposition temperature, the grain growth rate gradually exceeded the nucleation rate, and the morphology of manganese oxide deposits changed from nano-particles to nano-fiber clusters. Among them, nano-slice (petal)-like, nano-bead, nano-particle / column is the transition state of the particle to the fiber, respectively. The morphology is affected by the size of nucleation rate and the relationship between growth rate and nucleation rate during crystal growth. The deposition conditions are as follows: deposition temperature 0 掳C, deposition voltage 0.75 V, sample area specific capacitance 0.311 F / cm-2 (scanning rate 10 MV / s / 1), when the area specific capacitance is maximum at the same amount of electricity (Q = 1.8 C), the deposition temperature is 0 掳C, the deposition voltage is 0.75 V, and the specific capacitance of the sample is 0.311 F / V. The morphology is nano-string beads.
【学位授予单位】：华南理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TM53
【参考文献】
相关硕士学位论文 前1条
1 崔德源;二氧化锰电极材料制备与性能研究[D];大连理工大学;2011年
，本文编号：2470966
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