全钒氧化还原液流电池的研究

【作者】 王彩虹；

【导师】 钟朝位；

【作者基本信息】 电子科技大学 ， 材料物理与化学， 2005， 硕士

【摘要】 全钒氧化还原液流电池是一种新型绿色的二次电池,具有容量和功率可调、大电流无损深度放电、使用寿命长、易操作和维护等优点。它作为一种单一金属离子的大型储能系统,避免了传统铅酸电池和Fe/Cr 电池的电解液交叉污染问题,在应用于再生能源的固定储能装置方面,展示了很大的优势。它既可以通过电力充电又可以通过交换电解液方式机械充电的特性,使得它在应用于车载电源方面备受人们的关注。然而,从理论走向钒电池的实际应用,仍然存在很多问题。制备高纯度的钒离子电解液、选择合适的电极和隔膜、通过一些活化方法来改进电极的催化活性以及设定适当的电池充放电运行参数,对提高钒电池的能量密度和效率,加快它在中国的商业化进程具有重要的意义。本论文采用粉末溶解和电解氧化还原相结合的方法制备出了四个不同价态的高浓度钒离子的硫酸溶液,并用循环伏安法研究它们在电极上的可逆性,结果表明:在扫描范围内均出现V(II)/V(IV)和V(IV)/V(V)电对的氧化和还原特征峰,而且电解液浓度和扫描速率的增加使峰电流值增大,但同时扫描速率的增加,也使峰电位间距不断增大。对多孔聚丙烯腈基石墨毡进行热活化和酸活化处理,然后将它与碳-聚合物导电塑料板粘合制成复合电极用于电池中,从电池电阻来判断活化的效果表明,热处理的最佳条件为400℃和30h,酸处理的最佳条件为98%浓硫酸和5h。并结合电极反应分析了活化的催化机理。本实验选择性能较优的进口nafion 117 膜作为电池的隔膜;综合考虑各因素,对电池的组件进行了优化设计;组装出了实验室水平的单电池;对其进行循环充放电,分析了电极、电极间距、钒离子浓度、硫酸浓度、充放电电流、隔膜等因素对电池充放电性能的影响,并给出了适用于电池充放电运行的参数。全钒氧化还原液流电池的循环充放电实验表明:放电电流可大于900mA,最大放电电压可达1.46V,所获得的最高体积比能量为12.95Wh/L,最高电流转换效率可高达99%。自放电监测实验还表明:其自放电程度很小,适于长期使用。更多还原

【Abstract】 All vanadium redox flow battery (AVRFB) is a new-style secondary battery that has many characteristics. As a single-metal system, AVRFB overcomes the problem of cross-contamination of the two half-cell electrolytes that traditional lead Acid battery and Fe/Cr battery has encountered, so it is showing promising results for various stationary applications such as remote area power systems, load leveling at power plants and emergency back-up applications. The advantage that can be both electrically recharge and mechanically refueled has attracted much attention on its application in electric vehicles. However, there are still some questions to be solved, not only on the theory but also on the practical application. They are preparing high purity vanadium electrolyte, choosing suitable electrode and membrane, improving the catalysis performance of the electrode through some activate methods, and controlling the proper operation parameter of the charge and discharge. Investigation of above-mentioned themes is very important for improving the energy density and the efficiency of AVRFB and Accelerating its commercialization in China. In this paper, high concentration vanadium electrolyte has been prepared by the dissolve and electrolysis. Their reversibility has been evaluated by the cyclic voltammetry. The result showed that the four characteristic peaks of V(II)/V(IV) and V(IV)/V(V) redox couples appears on the all voltammograms; the higher the concentration of the electrolytic liquid and the scan rate are, the bigger the peak current is; but the increase of speed of scanning make the peak potential separation wider. After the thermal treatment/acid Treatment, the porous PAN based graphite felt electrode has been bonded to Carbon-Polymer Conducting Plastic. So Composite Electrode has been obtained. The influence of modification is judged by the cell resistance. It is proved that the optimum condition of thermal treatment and acid treatment are 400??, 30h and 98% sulphuric acid solution, 5h. And combined with the electrode reaction, the mechanism of Catalysis is analyzed. In experiment, the import nafion 117-membrane is selected as the battery separator. In view of the several factors, the optimization design is made in all packages of battery. A lab-level vanadium battery has been constructed. In terms of results of charge/diacharge更多还原