威达蓄电池提高铅酸蓄电池循环寿命的研究

提高铅酸蓄电池循环寿命的研究：

环使用寿命达不到要求。

铅酸蓄电池的寿命终止多因容量不足，而对于蓄电池来说，其循环寿命更是其众多指标中的关键指标。对于阀控铅酸蓄电池,延长电池循环寿命的公认措施是铅膏配方中增加长效添加剂、采用高锡低钙合金、极板高温固化、提高装配压力等等。

但即使全部采取以上措施,生产出的电池寿命也不一定能达到国外电池寿命的水平。尤其是随着成本压力的增加,很多国内中小企业为了降低生产成本,提高电池的大电流放电性能,不断地降低电池的极板厚度和增加电解液的比重,这对于电池的整体性能,尤其是循环性能来说无疑是杀鸡取卵的方法。

本项目的研究重点即是在上述各项延长电池循环寿命的措施都采取的情况下,重点研究电池正负极板厚度、电解液比重和不同充电条件对电池初期容量、国标循环寿命和1h率99.99%DOD循环寿命的影响。

1 试验内容

针对以上研究内容,采用两种极板厚度的电池结构,配合4种电解液比重,制作12V、7Ah电池以进行各项性能试验。

1.1 电池制造

电池制造采用3正4负(正极板厚度为3.6mm)、4正5负(正极板厚度为2.8mm)两种结构装配，铅膏配方为今星光公司长寿命铅膏配方，极板为槽化成工艺生产，电池装配后分别加1.27、1.29、1.31、1.33四种比重电解液，加酸量控制单体内有效酸量均相同。电池按照工艺初充电完成后测试电池重量和内阻，两种结构电池的重量分别约为2.60kg和2.45kg，内阻分别约为19mΩ和17mΩ。之后分别测试各类电池的初期容量和两种循环寿命，为清楚表示各类正交试验电池的特点和试验项目，各类电池正交试验情况如表1所示。

1.2 初期性能测试

表1中的各类电池制作完成后，分别测试各类电池20h和3C容量，作为电池初期容量进行比较考核。

1.3 国标循环寿命

电池经过初期容量测试合格后,按照小型阀控密封式铅酸蓄电池***标准(标准代号为GB/T 196391.1-2005)5.18寿命试验方法测试表1中6类电池的寿命。

1.4 恒流限压(LV)寿命试验

根据各类电池的两项试验情况,采用不同的恒流限压充电方法测试表1中4类电池的1h率放电99.99%DOD循环寿命。

1.5 电池解剖分析

将上一试验步骤中寿命终止的电池解剖,采用化学方法分析正负极活性物质含量、负极硫酸铅含量以及酸比重等,并确定电池寿命终止的原因。

2 试验结果分析讨论

2.1 电池初期性能试验

电池制作完成后,对各类电池分别任意取3只,按照国标方法测试电池的20h率放电和3C放电,对3只电池的放电数据取平均值,如表2所示。

由表中数据可以看出:各类电池放电测试都能够达到***标准要求的20h率放电20h和3C放电7min的要求。但是,随着极板变薄、电解液比重增加,不论是20h率容量还是3C容量,都呈增长趋势,尤其是3C放电时间增加得更加明显。

2.2 国标循环寿命

根据各类电池初期容量的测试情况,采用小型阀控铅酸蓄电池***标准中5.18条所规定的电池循环寿命测试方法,对3正4负极板结构的4种酸比重的电池和4正5负极板结构的1.29和1.31两种酸比重的电池,各取2只进行循环寿命试验。试验数据见表3。

为了了解电解液比重和极板厚度等对电池循环寿命的影响，将表中数据分类后分别做出图1(3正4负结构电池国标循环寿命随电解液不同的影响)和图2(不同极板厚度对电池循环寿命的影响)。

图1 电解液密度对电池国标寿命的影响

图2 不同极板厚度对电池国标循环寿命的影响

由表3、图1和图2可知,上述各类电池的国标循环寿命都大于标准的300次的要求。但是随着电解液比重的增加和极板厚度的减薄,电池循环寿命呈明显下降趋势。

2.3 恒流限压(LV)寿命试验

根据上述各项试验的情况,取3正4负极板结构,酸比重分别为1.29和1.31的A1B2和A1B3两类电池进行1h率的99.99%DOD寿命试验。充电方法为恒流限压,恒流值为0.15C,限压值分别为14.2V/只、14.5V/只和14.8V/只。每一类电池用各种充电方法测试3只电池,试验结束后将3只电池的循环次数取平均值列于表4中。

由表4数据可以看出:对于电解液比重为1.29的电池来说，随着充电限压值的逐步增大，电池循环寿命逐步减小，采用14.2V/只的限压值充电，循环寿命最长。而对于电解液比重为1.31的电池来说，则是采用14.5V/只限压值充电的电池寿命最长，采用其他两个限压值充电的电池寿命明显少得多。

2.4 电池解剖分析

将进行LV试验的各组电池寿命终止后,各取有代表性的电池一只,解剖分析正负极活性物质含量、负极硫酸铅含量和隔膜内电解液比重等,并初步确定电池失效原因。具体情况见表5。

对表5中的数据进行分析,并结合表4中的循环寿命数据可以得出结论:对于酸比重为1.29的电池循环寿命终止的原因主要是充电过程中正极活性物质泥化、正极板栅腐蚀和失水等,充电过程电池失水的同时也提高了电解液比重。而对于酸比重为1.31的电池,现象和趋势基本相同,只是采用14.2V/只充电时易导致电池充电不足,出现负极硫酸盐化现象。

3 结束语

通过对不同极板厚度、添加不同比重电解液的电池,进行初期容量、国标循环寿命和不同恒流限压充电控制条件下的循环寿命试验,以及对循环寿命终止电池的解剖分析,得出以下结论:电池极板越厚,电解液比重越低,电池的初期容量相对越低,尤其是大电流放电性能降低得更加明显,但是电池的循环寿命则明显延长。

对于电解液比重较大的电池,合理选择恒流限压充电的限压值,能够避免电池的负极硫酸盐化和正极泥化,延长电池循环寿命

Research on improving the cycle life of lead-acid batteries:

The service life of the ring can not meet the requirements.

The end of life of lead-acid batteries is mostly due to insufficient capacity, and for batteries, their cycle life is a key indicator among many indicators. For valve-controlled lead-acid batteries, the recognized measures to extend the battery cycle life are the addition of long-acting additives in the lead paste formula, the use of high tin and low calcium alloys, high temperature solidification of the plate, increasing the assembly pressure, and so on.

However, even if all the above measures are taken, the battery life produced may not be able to reach the level of foreign battery life. Especially with the increase of cost pressure, many domestic small and medium-sized enterprises in order to reduce production costs, improve the battery's high current discharge performance, and constantly reduce the thickness of the battery plate and increase the proportion of electrolyte, which is undoubtedly the method of killing the goose that lays the golden egg for the overall performance of the battery, especially the cycle performance.

The research focus of this project is to focus on the influence of positive and negative plate thickness, electrolyte specific gravity and different charging conditions on the initial capacity, national standard cycle life and 1h rate 99.99%DOD cycle life of the battery when the above measures to extend the battery cycle life are taken.

1 Test content

In view of the above research content, two kinds of plate thickness of the battery structure, with 4 kinds of electrolyte specific gravity, 12V, 7Ah batteries are made to carry out various performance tests.

1.1 Battery Manufacturing

Battery manufacturing adopts 3 + 4 negative (positive plate thickness is 3.6mm), 4 + 5 negative (positive plate thickness is 2.8mm) two kinds of structure assembly, the lead paste formula is Jin Xingguang company's long-life lead paste formula, the plate is produced by groove forming process, and 1.27, 1.29, 1.31, 1.33 kinds of specific gravity electrolyte are added to the battery assembly. The amount of acid added to control the effective amount of acid in the monomer is the same. After the battery is charged at the beginning of the process, the weight and internal resistance of the battery are tested. The weight of the two structural batteries is about 2.60kg and 2.45kg, and the internal resistance is about 19mΩ and 17mΩ, respectively. After that, the initial capacity and two cycle life of all kinds of batteries were tested respectively. In order to clearly represent the characteristics and test items of all kinds of orthogonal test batteries, the orthogonal test of all kinds of batteries was shown in Table 1.

1.2 Initial Performance test

After the production of all kinds of batteries in Table 1, the 20h and 3C capacities of all kinds of batteries are tested respectively, and the initial capacity of batteries is compared and assessed.

1.3 GB cycle life

After the initial capacity test of the battery is qualified, the life of the 6 types of batteries in Table 1 is tested according to the *** standard for small valve-controlled sealed lead-acid batteries (standard code is GB/T 196391.1-2005)5.18 Life test method.

1.4 Constant current and Voltage Limiting (LV) life test

According to the two tests of various types of batteries, the 1h rate discharge 99.99%DOD cycle life of the 4 types of batteries in Table 1 was tested by different constant current and voltage limiting charging methods.

1.5 Battery anatomy analysis

The end-of-life battery in the previous test step was dissected, and the content of active substances in the positive and negative electrodes, the content of lead sulfate in the negative electrode and the specific gravity of acid were analyzed by chemical methods, and the reasons for the end-of-life of the battery were determined.

2. Analysis and discussion of test results

2.1 Initial battery performance test

After the battery is made, 3 batteries of various types are randomly selected, and the 20h rate discharge and 3C discharge of the battery are tested according to the national standard method. The discharge data of the 3 batteries are averaged, as shown in Table 2.

It can be seen from the data in the table that all kinds of battery discharge tests can meet the requirements of 20h rate discharge 20h and 3C discharge 7min as required by the *** standard. However, as the plate becomes thinner and the specific gravity of the electrolyte increases, both the 20h rate capacity and the 3C capacity show an increasing trend, especially the 3C discharge time increases more significantly.

2.2 National standard cycle life

According to the initial capacity test of various types of batteries, the battery cycle life test method specified in article 5.18 of the small valve-controlled lead-acid battery *** standard is adopted, and two batteries with 4 acid specific gravity of 3 positive 4 negative plate structure and 1.29 and 1.31 acid specific gravity of 4 positive 5 negative plate structure are selected for cycle life test. The test data are shown in Table 3.

In order to understand the influence of electrolyte specific gravity and plate thickness on battery cycle life, the data in the table are classified and FIG. 1(the influence of 3 + 4 negative structure battery national standard cycle life with different electrolyte) and FIG. 2(the influence of different plate thickness on battery cycle life) are made respectively.

FIG. 1 Influence of electrolyte density on national standard battery life

FIG. 2 Influence of different plate thickness on national standard battery cycle life

As can be seen from Table 3, Figure 1 and Figure 2, the national standard cycle life of the above types of batteries is greater than the standard 300 times. However, with the increase of electrolyte specific gravity and the thinning of plate thickness, the battery cycle life showed an obvious decreasing trend.

2.3 Constant current and Voltage Limiting (LV) life test

According to the above tests, A1B2 and A1B3 batteries with 3 + 4 negative plate structure and acid specific gravity of 1.29 and 1.31 were selected for 99.99%DOD life test at 1h rate. The charging method is constant current and voltage limiting, the constant current value is 0.15C, and the voltage limiting values are 14.2V/ only, 14.5V/ only and 14.8V/ only respectively. For each type of battery, three batteries were tested by various charging methods. After the test, the average number of cycles of the three batteries was taken and listed in Table 4.

As can be seen from the data in Table 4, for the battery with electrolyte specific gravity of 1.29, the cycle life of the battery gradually decreases with the gradual increase of the charge voltage limit value, and the cycle life is longest when the voltage limit value of 14.2V/ battery is used to charge. For the battery with the electrolyte specific gravity of 1.31, the battery life of the battery charged with the 14.5V/ limited voltage value is the longest, and the battery life of the battery charged with the other two limited voltage values is significantly less.

2.4 Battery anatomy analysis

After the battery life of each group for LV test was terminated, a representative battery was taken from each group, and the content of active substances in the positive and negative electrodes, the content of lead sulfate in the negative electrode and the specific gravity of electrolyte in the diaphragm were dissected, and the cause of battery failure was preliminarily determined. For details, see Table 5.

Based on the analysis of the data in Table 5 and the cycle life data in Table 4, it can be concluded that the main reasons for the termination of the cycle life of the battery with an acid specific gravity of 1.29 are the sludge of the positive active substance, positive plate grid corrosion and water loss during the charging process. The water loss of the battery during the charging process also increases the specific gravity of the electrolyte. For the battery with an acid specific gravity of 1.31, the phenomenon and trend are basically the same, but the use of 14.2V/ only charging is easy to lead to insufficient battery charging, and negative sulphate phenomenon.

3 Closing remarks

Through the initial capacity, national standard cycle life and cycle life tests under different constant current and voltage limiting charging control conditions for batteries with different plate thickness and different specific gravity, as well as the anatomical analysis of batteries with end-of-cycle life, the following conclusions are drawn: the thicker the battery plate, the lower the specific gravity of the electrolyte, the lower the initial capacity of the battery, especially the high current discharge performance Lower is more obvious, but the battery cycle life is significantly extended.

For the battery with large proportion of electrolyte, the reasonable choice of constant current voltage limiting charging voltage limiting value can avoid the negative sulfate and positive sludge of the battery, and extend the battery cycle life