JP2005347032A - Sealed lead acid storage battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sealed lead acid storage battery in which the degradation of life performance can be suppressed by improving short circuit resistance. <P>SOLUTION: A separator with a structure in which a microporous film is clipped by glass fiber layers is used and inorganic powder is arranged between the glass fiber layers, thereby, a short circuit at the time of over discharge of the battery is suppressed. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a sealed lead-acid battery.

  A lead-acid battery has a feature that a positive electrode plate and a negative electrode plate are obtained by filling an active material into a current collector, and insulation between both electrodes is achieved by interposing a separator made of a fine glass fiber layer therebetween. Conventional sealed lead-acid batteries have a limited amount of electrolyte that can be held, and have a performance inferior to open batteries. In order to improve these aspects, it has been proposed to improve the performance by improving the retention of the necessary electrolyte by performing a process of arranging inorganic powder in the separator as in Patent Document 1.

JP-A-5-151947

  Conventionally, when a battery is left in an overdischarged state, lead sulfate originally present in the active material or lead sulfate produced by discharge is dissolved due to a significant decrease in sulfuric acid concentration. When charged in this state, lead sulfate is continuously deposited in the glass fiber layer in the separator. As a result, a short circuit between the two poles may be caused through the glass fiber, leading to a decrease in life characteristics.

  In order to solve the above problems, the sealed lead-acid battery separator of the present invention suppresses continuous precipitation of lead sulfate in a glass fiber layer, and further sandwiches a microporous film between the glass fiber layers. Furthermore, the short circuit suppression at the time of overdischarge leaving is aimed at.

  By using a separator having a structure in which a microporous film is sandwiched between glass fiber layers, and further by arranging inorganic powder between the glass fiber layers, it was possible to suppress a short circuit when left overdischarged. In addition, there is little influence of a decrease in output due to an increase in internal resistance of the battery.

  As a separator for a sealed lead-acid battery, it is desirable to have a three-layer structure in which one microporous film is sandwiched between two glass fiber layers from the viewpoint of manufacturing method and cost.

  Examples of cylindrical sealed lead-acid batteries to which the present invention is applied are shown below.

  First, a positive electrode plate and a negative electrode plate were obtained by filling a strip-shaped punched current collector, which is a Pb—Sb alloy, with a predetermined amount of active material. The separator was obtained by sandwiching a polyethylene film between the glass fiber layers by heat welding. In consideration of increasing the output of the battery, the thinnest separator thickness is suitable and is set to 0.4 mm. An attempt was made to dispose the inorganic powder in the glass fiber layer by dispersing colloidal silica so that the separator obtained was about 1.0 mg to 5.0 mg per electrode plate surface by a spray method. Thereafter, a separator as shown in FIG. 1 was produced through a drying process. Thereafter, winding was performed so that the separator was sandwiched between the positive electrode and the negative electrode, and an electrode group was obtained through an aging and drying process. The current collecting tab of the electrode plate group was subjected to group welding, and a lid was attached after inserting the group to obtain an unmodified 2V single cell. Thereafter, an electrolytic solution having a sulfuric acid specific gravity of 1.270 was injected, and an initial charge was performed under the conditions of an applied amount of 300%, 42 h, and 25 ° C., thereby producing a 2 V single battery having an initial capacity of 15 Ah. The produced batteries are shown in Table 1.

FIG. 2 shows the result of comparing the output characteristics by discharging the battery with the current (10, 30, 90, 180, 300, 500 A) set for the manufactured battery and measuring the battery voltage at 5 seconds. Although there was a concern that the internal resistance increased and the output characteristics of the battery decreased due to the treatment in which the polyethylene film was sandwiched between the glass fibers, Example 1 using the separator of the present invention was used from FIG. And in Example 2, it was the output performance equivalent to a comparative example. However, Example 3 with the thickest film thickness is inferior in output performance as compared with other examples.

  Next, a resistance is connected so that a current of 0.05 C (about 0.75 A) flows between the batteries with respect to the initial capacity of the manufactured battery, and the battery is left to stand for 4 days to easily leave a short circuit. Created an environment. Thereafter, constant voltage charging was performed at 2.5 V and 0.3 C (limited current 4.5 A). This was regarded as one cycle, and a short circuit was confirmed by a charge curve after the cycle was completed. FIG. 3 shows charging curves when not short-circuited and when short-circuited. First, when not short-circuited, the current attenuates when reaching a constant voltage. On the other hand, when a short circuit occurs, no current decay is observed until the end of charging. From such a viewpoint, the presence or absence of a short circuit was determined. This cycle is repeated for batteries that did not show a short circuit. FIG. 4 shows the change in the end-of-charge current associated with the cycle. The broken line in the figure indicates the life when the end-of-charge current reaches that current. First, the short circuit resistance in the presence or absence of inorganic powder in the glass fiber layer was compared. Since Comparative Example 1 in which the inorganic powder is arranged with respect to Comparative Example 2 having no inorganic powder is excellent in cycle characteristics, the effect of short circuit resistance can be obtained by arranging the inorganic powder in the glass fiber layer. It was. Compared with the other examples using the separator of the present invention, the results of the short circuit resistance were the same as or superior to those of the comparative example. Particularly, Example 3 having the thickest film thickness was a particularly excellent result.

  In this example, silica was used as the inorganic powder, but the same effect was obtained when alumina, titania, or the like was used as the same inorganic powder. Moreover, since the same effect is acquired even if these are mixed, it does not necessarily limit to one type.

It is sectional drawing of this invention separator. It is a figure which shows a battery output characteristic when this invention separator is used. It is a judgment figure of the presence or absence of the short circuit by constant voltage charge. It is a figure which shows the short circuit resistance of this invention goods.

Explanation of symbols

1 Microporous film 2 Inorganic powder 3 Glass fiber layer

Claims (2)

  A sealed lead-acid battery in which a positive electrode plate and a negative electrode plate constitute a plate group via a separator, the separator having a structure in which a microporous film is sandwiched between glass fiber layers, and the glass fiber layer is inorganic. Sealed lead-acid battery characterized by powder distribution.   The sealed lead-acid battery according to claim 1, wherein the inorganic powder is at least one of silica, alumina, and titania.

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