VRLA电池极板极化及失效模式研究

发布时间：2018-03-29 15:55

本文选题：铅酸蓄电池　切入点：极化　出处：《福州大学》2014年硕士论文

【摘要】：到目前为止,铅酸蓄电池仍然是最广泛使用的二次电池。受到板栅结构、电池温度、电流大小等因素的影响,电池极板各部位极化不同,从而对铅酸蓄电池性能产生很大影响,使不同部位的活性物质利用率存在差异。活性物质利用率越高部位,循环一定次数后,该部位失效越快。为改善电池设计,研究其失效模式是非常有必要的。本文研究了温度和板栅结构对放电期间极板极化以及电池性能的影响,研究了单体电池在充放电期间板极间的电势分布,同时还考察了极耳位置对电流分布的影响,研究了循环过程中电池失效原大。得到以下结论：1、测量22 Ah以及20 Ah电池在不同温度、不同放电倍率下极板的欧姆极化,结果表明：极板欧姆极化随着温度降低而减小,不同板栅结构明显影响极板上电流密度分布,22 Ah电池所用板栅上部竖筋多可明显降低极化,电流密度分布更均匀。电流在板栅上流动主要是在竖直方向筋条上，板栅设计时应考虑这因素,极板竖直方向上欧姆极化与放电电流大小成正比,25℃下22 Ah电池3C1 C、0.5 C放电时正极板上半部的欧姆极化分别为20 mV、6.8mV、3.45 mV。2、极板极耳位置变化影响极板两侧电势分布。中极耳极板上电流分布比边极耳极板的要均匀,活性物质利用率更高,中极耳极板电池与边极耳极板电池的2.5 A放电容量分别为4.45 Ah和3.98 Ah。测量电池充放电过程中正、负极板间的电势变化,结果表明：电池充放电期间正、负极板间电解液存在IR降,其值与电流值成正比,以2.5A、5A、15A电流恒流放电结束后,极板间电势差分别达到了0.131 V、0.197 V和0.553 V。3、对电池进行解剖和失效分析,结果表明：正极板上部活性物质软化脱落及板栅腐蚀是导致电池失效的原因。研究发现：(1)循环过程中正极活性物质的结品度在增加,逐渐失去无定型结构,且α-PbO2逐渐转化为β-PBO2。β-PbO2晶粒尺寸随着循环过程在不断变大,平均尺寸从31.8 nm长到了54.8 nm,脱落的活性物质部分甚至达到了73.7 nm,尺寸较大的活性物质与其他活性物质的接触变差,这部分活性物质便从极板上脱落下来：(2)正极板板栅不同部位的腐蚀的情况各不相同，上部的腐蚀明显比中部严重,当电池失效后,正极上部的板栅已经有约一半被腐蚀,腐蚀层内存在大量的小气孔以及裂缝,而板栅中部较完好；(3)放电后电池隔板中部电解液浓度比上部和下部的都要低。随着循环次数的增加,放电后隔板中电解液浓度有所增大,并且出现了轻微的分层现象。
[Abstract]:So far, two battery lead-acid battery is still the most widely used. By grid structure, battery temperature, current size, polarization of various parts of the battery plate, which has a great influence on the performance of the lead-acid battery, the active substance in different parts are different. The utilization rate of active material utilization rate is high part of the cycle after a certain number of times, the failure position more quickly. In order to improve the design of the battery, the failure mode is very necessary. This paper studies the temperature and grid structure influence on discharge during plate polarization and cell performance, the potential distribution in the plate during charging and discharging single battery research, at the same time the lug position was also investigated the effects on current distribution of cell cycle, the original failure. Get the following conclusions: 1, 22 Ah and 20 Ah cell measurements at different temperatures, different discharge times The ohmic polarization plates, the rate of the results show that the electrode ohmic polarization decreases as the temperature decreases, the different grid structure significantly affect the current density distribution on the plate, 22 Ah battery grid for the upper vertical reinforcement can significantly reduce the multi polarization, the current density distribution is more uniform. The current flow in the grid is mainly in the vertical direction ribs, grid design should consider these factors, vertical plate size and the discharge current is proportional to the ohmic polarization, 25 C 22 Ah battery 3C1 C, 0.5 C discharge ohmic polarization on the positive plate part were 20 mV, 3.45 6.8mV, mV.2, plate lug position changes on both sides of the plate the potential distribution in the lug. The lug plate edge than the uniform current distribution on the electrodes, active material utilization rate is high, 2.5 A discharge capacity in the lug plate and the lug plate side battery battery are respectively 4.45 Ah and 3.98 Ah. to measure the battery charge and discharge In the process of electric potential changes, positive and negative plates. The results showed that: during the battery charging and discharging positive and negative plates of electrolyte IR drop, the value and the current value is proportional to 2.5A, 5A, 15A and constant current discharge after the electric potential difference between plates respectively reach 0.131 V, 0.197 V and 0.553 V.3 the battery, anatomy and failure analysis, the results show that the softening of positive active material in the upper gate corrosion and the board is the cause of battery failure. The study found that: (1) positive active material cycle in crystallinity increased, gradually lose the amorphous structure and alpha -PbO2 gradually transformed into -PbO2 grain size -PBO2. cycle in beta beta with larger average size, from 31.8 nm to 54.8 nm, part of active material shedding even reached 73.7 nm, the larger size of the active substances and other active substances contact variation, this part of active substances Falling down from the plate: (2) plate gate cathode corrosion in different parts of the situation is different, the upper part of the corrosion is more obvious than the central serious, when the battery failure, the upper part of the cathode grid has about half of corrosion, the existence of a large number of small pores and cracks corrosion layer, while the grid is middle in good condition; (3) after discharge battery separator middle electrolyte concentration than the upper and lower parts are low. With the increase of the cycle, after discharge separator electrolyte concentration increased, and the emergence of stratification of minor.

【学位授予单位】：福州大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM912.1

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