【作者】 李祥；

【导师】 甘卫平；

【作者基本信息】 中南大学 ， 材料学， 2012， 博士

【摘要】 作为新一代储能器件,因其无可替代的优点,超级电容器目前是国际上公认的比电容最大、比功率最高,充放电性能最好的新型储能元件,是各个工业发达国竞相发展的新一代电容器。建立在法拉第充放电原理基础上的二氧化钌电极材料是制造高比容超级电容器的关键材料。薄膜电极材料性能的好坏直接影响超级电容器的性能。由于二氧化钌价格昂贵,限制了它的应用范围。因此,立足当今国内外超级电容器电极材料的技术发展前沿,本文重点研究了在不同复合体系、不同制备工艺下得到的氧化钌基复合电极材料对高比容超级电容器性能的影响规律,目的是发现电极材料性能与成本之间的规律。如何才能够大幅度降低材料成本,充分发挥电极材料的性能,提高电极材料的性价比,这对发展新一代高比容超级电容器,拓展其应用领域都具有深远意义。本文研究了各种工艺,制备了不同体系的氧化钌基复合电极材料。其中包括采用旋转涂敷热分解法制备了RuO2薄膜电极,对传统的胶体法工艺进行改良后获得RuO2/活性碳(AC)复合电极,采用电沉积法制备了RuO2/聚苯胺(PANI)复合电极,采用组合涂敷热分解法与电化学氧化法分别制备出RuO2/聚苯胺(PANI)和RuO2/聚吡咯(PPy)复合电极。在此基础上,深入系统地研究了氧化钌掺杂活性碳(AC)、聚苯胺(PANI)及聚吡咯(PPy)复合电极薄膜材料的制备工艺、组织形貌及结构对其电化学性能的影响规律,并对电极的比电容、等效串联电阻及循环寿命等综合性能进行了优化。主要的研究内容及结果如下：1.首次提出低成本旋转涂敷原位热分解法制备RuO2薄膜电极。该方法操作简单,对设备要求低,薄膜电极具有厚度均匀、附着力好及电化学性能优良等特点。当RuO2薄膜电极经260℃热处理3h时,获得了最好的综合性能：此时薄膜厚度控制在7.7～8.0μm,附着力达到18.00MPa,比电容及等效串联电阻(ESR)分别为705.3Fg-1和0.436Ω,经1000次循环后,比电容仅损失0.32%。2.首次提出和成功实现了RuO2/AC复合粉体直接涂敷的工艺技术,制备了性能好,成本低廉的RuO2/AC复合电极材料。该工艺解决了传统胶体法制备RuO2/AC复合电极存在的问题包括：(1)氧化钌粒度较粗引起电极生成的薄膜组织比表面积减小,导致比电容性能下降；(2)反应过程中生成的NaCl残余物很难消除干净；(3)在电极制备过程中使用机械压片工艺,使得复合材料与基体附着力下降,造成复合材料与基体剥离而失效等问题。直接涂覆RuO2/AC复合粉体创新了复合电极材料制备的低成本短流程工艺技术。3.揭示了RuO2/AC复合材料热处理温度及活性碳含量对其物相结构及电化学性能的影响规律。研究结果表明该复合电极材料在240℃热处理4h后,可获得最大比电容445Fg-1和充放电性能的最佳匹配。当热处理温度高于270℃时,有较多的晶体相出现,电容量下降；研究发现在RuO2/AC复合体系中,当AC含量为27.65wt.%时,相应的复合电极的比电容最高,为582Fg-1,经1000次循环后损失10.4%。4.探索和优化了电化学沉积及其涂敷热分解组合法制备RuO2/PANI复合电极。首先,采用电沉积法作为比较态,制备了RuO2/PANI复合电极,其比电容为474Fg-1,经1000次循环后,比电容损仅损失12%；其后,采用电化学沉积及其涂敷热分解组合法制备RuO2/PANI复合电极。该法发挥两种工艺的优势,即利用电沉积法获得高的薄膜附着力,利用涂敷法节省贵金属原材料,消耗的RuCl3nH2O大约是电沉积法的1/15。组合法制备的复合电极中,PANI粒子较细,与Ru02薄膜形成良好的结合界面,该电极的比电容可达478Fg-1,经1000次循环后,比电容仅损失11%。5.揭示了组合法制备RuO2/PPy复合电极沉积时间、电流密度及吡咯单体浓度等工艺参数对电极的形貌和电化学性能的影响规律。研究发现,当沉积时间为25min,电流密度为2.4mA·cm-2时,苯胺单体浓度为0.20mol-L’1时,制备的复合电极能够获得最好的性能,其比电容可达486Fg-1,经1000次循环后仅损失9.8%。更多还原

【Abstract】 Owing to its irreplaceable advantage with highest specific capacitance and specific energy, as well as the best charge and discharge property, supercapacitor has been considered as one of the new energy storage devices worldwide.Based on Faraday charge and discharge principle, RuO2has been identified as the key electrode material to make high specific capacitance supercapacitors. However, the application of RuO2was limited due to its high cost. Therefore, established on the frontier of the developing technology of supercapacitor electrode materials at home and abroad today, this paper focuses on the effects of RuO2-based electrode prepared with different composite systems and different methods on properties of high specific capacitance supercapaciors, aiming to find the law between its performance and cost. It is far-reaching significant for developing new high specific capacitance supercapacitor and enlarging application rang to figure out how to greatly reduce the cost and give full play to its performance.In this paper, we have studied different technics to prepare RuO2-based composite electrode with different systems, including rotation coating situ thermal decomposition method to prepare RuO2film electrodes, modified traditional colloidal method to prepare RuO2/activated carbon (AC) composite electrode, electrodeposition method to prepare RuO2/polyaniline (PANI) electrode and the combination of thermal decom-position and electrochemical oxide method to prepare RuO2/PANI and RuO2/polypyrrole (PPy) composite electrode. Based on those cases, we haved made further study on the effects of preparation, morphology and microstructure of RuO2composite electrode film doped with AC, PANI and PPy on electrochemical properties of electrodes, and we also optimized the property of specific capacitance, equivalent series resistance and cycle life of the electrode. The major findings of this paper are as follows:1. RuO2film electrode prepared by low cost and rotation si-tu coating thermal decomposition method is proposed for the first time. This method is easy to manipulate with low requirements for devices, and electrodes film has uniform thickness, excellent adhesion and great electrochemical properties, et al. The best comprehensive properties of RuO2film electrodes are obtained when RuO2film electrodes were annealed at260℃for3h. Meanwhile, the film thickness is7.7～8.0μm, adhesion gets18.00MPa, specific capacitance reaches705.3Fg-1and equivalent series resistance (ESR) lows to0.436Ω, and specific capacitance only loses0.32%after1000cycles.2. We firstly proposed a direct coating technology using RuO2/AC composite powders to prepare low cost and well performed RuO2/AC composite electrode. This method solved a series of problems of RuO2/AC composite prepared by traditional colloid method which includes problems such as:1) specific surface of film in electrode formed by coarse grain ruthenium oxide films declines and leads to specific capacitance decrease,2) NaCl generated in the reaction could hardly be eliminated,3) the mechanic tablet technology is used in the electrode preparation, this decreases the adhension between composite material and matrix, and finally makes the composite material spin off the matrix and leads to failure, etc. Direct coating RuO2/AC composite powders method has renovated the low cost and short technology of preparing composite electrode materials.3. The effect of annealing temperature and loading of activated carbon on phase structure and electrochemical properties of RuO2/AC composite electrode is revealed. The result shows that the highest specific capacitance of445Fg-1and excellent charge and discharge performance is obtained when RuO2/AC composite is annealed at240℃for4h. The capacitance decreases and more crystal phases appear when annealing temperature raises to270℃. In addition, study shows that the optimized content of activated carbon is27.65wt.%at which comes the highest specific capacitance of582Fg-1with only10.4%loss of specific capacitance after1000cycles.4. RuO2/PANI composite electrode prepared by electrodeposition and thermal decomposition combination method is explored and optimized. Firstly, as compasion, RuO2/PANI composite electrode has been prepared by electrodeposition method, and its specific capacitance is 474Fg-1, and only loss12%after1000cycles. Next, the composite electrode was prepared by electrodeposition and thermal decomposition combination method. The combination of the two methods can performs the advantages of both two preparations, that is to say, electrodeposition method can obtain high film adhesion, and thermal decomposition save precious metals of RuCl3.nH2O, and the amount of RuCl3.nH2O consumed by coating method is about1/15that of electrodeposition method. PANI particles prepared by combined method are fine and with good interface. The specific capacitance reaches478Fg-1and only loses11%after1000cycles.5. The effect of deposition time, current density and pyrrole monomer concentration on morphology and electrochemical performance of RuO2/PPy electrode prepared by combination method was revealed. The results show that the composite electrode obtains the best properties which specific capacitance reaches486Fg-1and only loses9.8%after1000cycles when deposition time, current density and pyrrole concentration are25min,2.4mA-cm-2and0.20mol·L-1, respectively.更多还原