液流电池泡沫炭复合涂层电极制备及其储电性能研究

发布时间：2018-05-18 12:06

本文选题：液流电池 + 泡沫炭复合涂层　；参考：《西安理工大学》2017年硕士论文

【摘要】：分布式电站是新能源实现就地消纳和长足发展的重要电力设施,其核心是开发大容量、高性能和低成本的储能系统。依据溶液中Pb2+以固态PbO2和Pb形式储电并可逆转换的永久性,单液流无隔膜的廉价性,功率和容量分别通过电极对数和Pb2+浓度可调控的灵活性,H2O2可回收残余储电层并达到无污染的环保性,铅酸液流电池引起分布式储能电站领域的高度关注。但目前因使用的传统石墨板和泡沫炭电极导电性较差、比表面积小和析氢过电位小等因素影响,电池表现出负极枝晶严重,储能容量较小,充放电效率较低等不足。基于此,本文以泡沫炭为基体进行化学镀铜和电沉积铅,系统研究泡沫炭复合涂层的制备工艺、机理和涂层相关性能;探索泡沫炭复合涂层电极较石墨板和泡沫炭所具有的优良理化和结构特性在铅酸液流电池应用中对储电沉积层和效率的影响及其提升电池容量的机理。研究表明:对泡沫炭基体前处理,化学镀铜后电沉积铅制备泡沫炭复合涂层。合理粗化基体增强与镀铜层间的机械结合,施镀中间铜层增强与镀铅层间的电化学结合。控制化学镀铜厚度3 ～4 μm和电沉积铅电流密度20 mA/cm2及其他工艺参数可得到表表面平整和颗粒均匀的镀层。化学镀铜机理遵循电化学混合电位理论,生长过程通过Cu胞的融合进行;电沉积铅遵循电结晶理论,从电化学角度分析可分为欠电位沉积和过电位沉积。泡沫炭复合涂层理化特性方面:经冷热循环法定性检测镀层结合力良好,XRD分析镀层无杂质元素掺入。化学镀铜层厚度3～4 μm时电极电导率高达1315.79 s/cm且电极载流量满足30～40 mA/cm2的要求;复合高韧性铜/铅涂层有效阻止预裂纹于薄弱骨架上集结,其整体压缩强度提高至0.5 MPa;经循环伏安测试泡沫炭复合涂层电极具有较好的电极反应可逆性,并随扫描速度和循环次数增加,电极反应可逆程度增强。结构特性方面:孔隙率高达93.71%,表观密度0.663 g/cm3体现其优良的轻质多孔特性;电极真实表面积为石墨板3～4倍。泡沫炭复合涂层负极上储电Pb层的颗粒较石墨板和泡沫炭电极均匀细腻,且其表面多孔结构有效分散电荷而不易枝状结晶。所对正极上储电Pb02层的颗粒结合紧凑或因电场均匀密集而影响正极羟基自由基OHads的分布。泡沫炭复合涂层负极因其表面理化特性和结构特性而具有较小的电极反应极化过电位和欧姆分压,使得电池充放电库伦效率高达93%～95%,电压效率89%～90%,能量效率83%～85%电极表面容量提高至50 nmAh/cm2时库伦效率仍稳定在96±0.5%,并且表现出极佳的快速充放电性能。
[Abstract]:Distributed power station is an important power facility for local absorption and rapid development of new energy. Its core is to develop large capacity, high performance and low cost energy storage system. According to the permanent storage and reversible conversion of Pb2 in solution in the form of solid PbO2 and Pb, the single flow without diaphragm is cheap. The power and capacity can be recovered from the residual storage layer by the logarithm of electrode and the flexibility of Pb2 concentration. Lead acid flow battery has attracted great attention in the field of distributed energy storage power plant. However, due to the poor conductivity, small specific surface area and low hydrogen evolution overpotential of traditional graphite plate and foamed carbon electrode, the battery shows negative dendrite, low energy storage capacity and low charge / discharge efficiency. Based on this, electroless copper plating and electrodeposition of lead were carried out on the base of foamed carbon, and the preparation process, mechanism and related properties of the coating were systematically studied. To explore the effect of the excellent physicochemical and structural properties of the composite coated electrode on the storage layer and efficiency of lead-acid liquid battery compared with graphite plate and foamed carbon and the mechanism of improving the battery capacity. The results showed that the carbon foam composite coating was prepared by electroless copper plating. The mechanical bonding between coarsening matrix and copper plating layer is reasonable, and the electrochemical bonding between copper plating layer and lead coating layer is also discussed. By controlling electroless copper plating thickness of 3 ~ 4 渭 m and electrodeposition current density of 20 mA/cm2 and other process parameters, a flat and uniform surface coating can be obtained. The electroless copper plating mechanism follows the electrochemical mixing potential theory, and the growth process is carried out by the fusion of Cu cells, and the electrodeposition of lead follows the electrocrystallization theory, which can be divided into underpotential deposition and overpotential deposition from the electrochemical point of view. The physicochemical properties of carbon foam composite coating were determined qualitatively by hot and cold cycle method. XRD analysis showed that there was no impurity element in the coating. When the thickness of electroless copper coating is 3 ~ 4 渭 m, the conductivity of the electrode is up to 1315.79 s/cm and the electrode current meets the requirement of 30 ~ 40 mA/cm2, and the composite high toughness copper / lead coating can effectively prevent the pre-crack from accumulating on the weak skeleton. The overall compressive strength of the electrode was increased to 0.5 MPA, and the electrode reaction reversibility was tested by cyclic voltammetry, and the reversible degree of electrode reaction increased with the increase of scanning speed and cycle times. The porosity is 93.71, the apparent density is 0.663 g/cm3, and the real surface area of the electrode is 3 ~ 4 times that of graphite plate. The particles of Pb layer on the negative electrode of carbon foam composite coating are more uniform and fine than those of graphite plate and foamed carbon electrode, and the porous structure of the surface is effective in dispersing charge but not in dendritic crystallization. The particle binding of the Pb02 layer on the positive electrode is compact or the distribution of the hydroxyl radical OHads is affected by the uniform and dense electric field. Because of the physical and chemical properties and structural characteristics of carbon foam composite coating, the electrode reaction polarization overpotential and ohmic partial pressure are smaller. The charge / discharge Coulomb efficiency of the battery is as high as 933 / 95, the voltage efficiency is 8990 / 90, and the energy efficiency of 830.85% electrode surface is increased to 50 nmAh/cm2, the Coulomb efficiency is still stable at 96 卤0.5, and it shows excellent rapid charge and discharge performance.
【学位授予单位】：西安理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TM912

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