JP2006185743A - Control valve type lead-acid battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a low-cost control valve type lead-acid battery excelling in a discharge capacity, a cycle life and charging efficiency and facilitating the injection of an electrolyte. <P>SOLUTION: In this control valve type lead-acid battery, 0.5-5.0 mass% of silica fine particles and 0.25-3.0 mass% of aluminum sulfate are added in the electrolyte. In the control valve type lead-acid battery, since an appropriate amount of silica fine particles is added in the electrolyte, the electrolyte is moderately gelled and a stratification phenomenon hardly occurs. Thereby, the control valve type lead-acid battery excels in discharge capacity (initial capacity ratio) and cycle life, has a good electrolyte injection property, and is manufacturable without needing much material cost. In addition, the control valve type lead-acid battery excels in charging efficiency because an appropriate amount of aluminum sulfate is added in the electrolyte. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a control valve type lead-acid battery that is excellent in discharge capacity, cycle life, and charging efficiency, is easy to inject electrolyte, and is low in cost.

  The control valve type lead-acid battery can be sealed by consuming the oxygen gas generated at the positive electrode during overcharge at the negative electrode and returning it to water, and the oxygen gas generated when the internal pressure of the storage battery rises abnormally in case It is a lead acid battery provided with the valve body which operate | moves with the predetermined pressure for letting out outside.

  In a control valve type lead-acid battery, the electrolyte is only impregnated in the separator and the electrode plate, and therefore the electrolyte is non-fluidized, so that concentrated sulfuric acid settles during charge and discharge in liquid lead-acid batteries. Thus, it is considered that the stratification phenomenon in which the specific gravity of the electrolytic solution becomes higher at the lower part of the electrode plate is less likely to occur. When this phenomenon occurs, the lower part of the electrode plate does not contribute to the electrochemical reaction, so that the battery capacity is reduced, and the reaction at the electrode plate becomes non-uniform so that the cycle life is reduced.

  As means for suppressing these phenomena, a gel-type control valve type lead-acid battery in which a gelling agent such as silica is mixed in an electrolytic solution is known. As these gel-type control valve type lead acid batteries, a control valve type lead acid battery (Patent Document 1) in which 5.0 to 8.0% by mass of silica fine particles are added to gel the electrolyte solution has been proposed. This control valve type lead storage battery injects electrolyte into the battery case of the storage battery during its manufacturing process, but at that time silica does not spread over the entire electrode plate group, and a sufficient effect cannot be obtained, Further, when the space above the electrode plate group is narrowed to increase the capacity by increasing the proportion of the electrode plate group in the battery case, it is difficult to inject the electrolyte. In addition, since the amount of silica fine particles added is large, it is disadvantageous in terms of cost.

JP 2003-36831 A

The inventors of the present invention have studied an amount of silica fine particles added that can suppress the stratification phenomenon of the electrolytic solution and do not impair the injection property of the electrolytic solution, and an electrolytic solution additive that enhances charging efficiency. As a result, the addition amount of the silica fine particles necessary for suppressing the stratification phenomenon is 0.5% by mass or more, and the addition amount of the silica fine particles that do not impair the electrolyte injection property is less than 5.0% by mass. In addition, the inventors have found that aluminum sulfate is suitable for the electrolyte additive, and have further studied and have completed the present invention.
An object of the present invention is to provide a control valve type lead-acid battery that is excellent in discharge capacity, cycle life, and charging efficiency, is easy to inject electrolyte, and is low in cost.

  In the first aspect of the present invention, silica fine particles are added in an amount of 0.5% by mass or more and less than 5.0% by mass, and aluminum sulfate is added in an amount of 0.25% by mass or more and 3.0% by mass or less. It is the control valve type lead acid battery characterized by having.

  In the control valve type lead-acid battery of the present invention, an appropriate amount of silica fine particles is added to the electrolytic solution, so that the electrolytic solution is appropriately gelled. Therefore, the stratification phenomenon hardly occurs, and thus a good discharge capacity and cycle life can be obtained. In addition, liquid injection is easy and raw material costs are low. Furthermore, since an appropriate amount of aluminum sulfate is added, the charging efficiency is excellent and good cycle life characteristics can be obtained.

  In the present invention, since the silica fine particles are added to the electrolytic solution, the electrolytic solution gels due to a temperature increase in the initial charge after the injection. The reason why the amount of silica fine particles added to the electrolytic solution is specified to be 0.5% by mass or more and less than 5.0% by mass is that the gel degree (degree of gelation) is low and the stratification phenomenon is less than 0.5% by mass. This is because it cannot be sufficiently suppressed. On the other hand, when the content is 5.0% by mass or more, the gelling agent in the electrolytic solution does not spread uniformly in the electrode plate group, the injection of the electrolytic solution becomes difficult, and the raw material cost increases.

  In the present invention, aluminum sulfate maintains the negative electrode active material in a fine state to increase charging efficiency. The reason why the amount of aluminum sulfate added is specified to be 0.25% by mass or more and 3.0% by mass or less is that the effect is not sufficiently obtained outside the specified value. A particularly preferable addition amount of aluminum sulfate is 0.5% by mass or more and 2.0% by mass or less.

  The control valve type lead acid battery of the present invention also includes a control valve type lead acid battery in which other additives for improving battery characteristics are added to the electrolytic solution in addition to silica fine particles and aluminum sulfate.

  A plurality of negative electrode conversion plates and positive electrode conversion plates produced by a known method are alternately laminated through glass mats made of long glass fibers having a diameter of 19 μm, and the same-polarity plate ears of this laminate are added together with lead. The electrode plate group was welded with a burner.

  Next, the electrode plate group was inserted into an ABS battery case, a lid was applied with an adhesive, and an electrolyte was injected from a liquid inlet of the lid to produce a 12V-38 Ah control valve type lead storage battery.

To the electrolytic solution, 1.0% by mass of aluminum sulfate (Al ₂ (SO ₄ ) ₃ ) is added to dilute sulfuric acid having a specific gravity of 1.300 (20 ° C.), and silica fine particles are within the specified range of the present invention (0 0.5 mass% or more and less than 5.0 mass%) and various amounts added.

The obtained respective valve-regulated lead-acid batteries, the discharge current 8A (0.25 C _5), and a discharge termination voltage 10.2V, the charging current 6.4A (0.2 C _5), a constant of the constant voltage 14.7V A cycle test was conducted in which constant current charging (charging time: 8 hours) was one cycle. The number of cycles when the discharge capacity reached 70% of the initial capacity was defined as the life.

  [Comparative Example 1] A lead-acid battery was produced by the same method as in Example 1 except that the silica fine particles were not added or the addition amount of the silica fine particles was outside the specified value of the present invention. I investigated.

The test results of Example 1 and Comparative Example 1 are shown in Table 1.
Table 1 also shows the evaluation results of the electrolyte injection property and cost.

  As is apparent from Table 1, No. 1 in Example 1 was obtained. Each of Nos. 1 to 6 (example products of the present invention) exhibited excellent life performance when the cycle life was 400 times or more. This is because a suitable amount of silica fine particles was contained and no stratification phenomenon occurred, and the charging efficiency was improved by the addition of aluminum sulfate. Further, since the amount of silica fine particles added was small, the electrolyte did not gel before the injection, and the injection could be performed easily. Moreover, raw material costs were low.

  On the other hand, No. 1 of Comparative Example 1 was used. No. 7 contained no silica fine particles and the electrolyte did not gel. In No. 8, since the addition amount of silica fine particles was small and the gel degree was low, the stratification phenomenon occurred and the cycle life was reduced in all cases. No. In No. 9, the amount of silica fine particles added was large, and the electrolyte gelled before injection, making it difficult to inject into the battery case. Raw material costs were also high.

Silica fine particles are added in an amount of 1.0% by mass to dilute sulfuric acid having a specific gravity of 1.300 (20 ° C.), and aluminum sulfate hydrate is added in various amounts within a range of 0.25 to 3.0% by mass in terms of aluminum sulfate. A control valve type lead storage battery was manufactured by the same method as in Example 1 except that the added electrolyte was used.
About each obtained control valve type lead acid battery, the cycle test was done on the same conditions as Example 1. FIG.

(Comparative Example 2)
A control valve type lead-acid battery was manufactured in the same manner as in Example 2 except that aluminum sulfate hydrate was not added or the amount added was outside the specified range of the present invention (no added and 4% by mass added). Then, a cycle test was performed by the same method as in Example 2.
The investigation results of Example 2 and Comparative Example 2 are shown in FIG. The horizontal axis represents the number of cycles, and the vertical axis represents the initial capacity ratio (ratio of capacity at the end of each cycle to the initial capacity).

  As is apparent from FIG. 1, No. 2 of Example 2 (example product of the present invention). 11 (addition of 0.25% by mass of aluminum sulfate) to 14 (addition of 3.0% by mass of aluminum sulfate) all had a high initial capacity ratio of 99% or more. This is because an appropriate amount of silica fine particles was contained in the electrolytic solution and no stratification phenomenon occurred, and an appropriate amount of aluminum sulfate was contained to improve charging efficiency. In particular, No. 1 containing 1.0% by mass of aluminum sulfate. 12 and 2.0% by mass. No. 13 had a high initial capacity ratio of approximately 102% or higher.

  On the other hand, the comparative example 2 No. No. 15 was obtained by adding 4.0% by mass of aluminum sulfate, but because the electrochemical reaction was inhibited due to the addition amount being too large, No. 15 was also added. In No. 16, since aluminum sulfate was not added and sufficient charging efficiency was not obtained, the initial capacity ratio decreased to 95% or less from the point where all exceeded 70 cycles.

  Based on the results of the cycle test conducted in Example 2, the charging rate (charge capacity / discharge capacity) was determined every 10 cycles. No. 12 (examples of the present invention) and No. The result of 16 (comparative example) is shown in FIG.

  As is clear from FIG. 2, the product of the present invention (No. 12) had a charging rate substantially equal to that of the comparative product (No. 16). In this way, the product of the present invention has a high initial capacity ratio (see FIG. 1), although the charging rate is almost the same as that of the comparative product, that is, the discharge is maintained at a high capacity. Means that the product of the present invention has improved charging efficiency. This improvement in charging efficiency is due to the addition of an appropriate amount of aluminum sulfate.

It is a figure which shows transition of the initial stage capacity ratio in the cycle test of the control valve type lead acid battery of this invention. It is a figure which shows transition of the charging rate in the cycle test of the control valve type lead acid battery of this invention.

Claims (1)

Control in which silica fine particles are added to the electrolytic solution in an amount of 0.5% by mass or more and less than 5.0% by mass, and aluminum sulfate is further added in an amount of 0.25% by mass or more and 3.0% by mass or less. Valve-type lead acid battery.