JPH0845537A - Lead acid battery - Google Patents

Abstract

(57) [Summary] [Purpose] To provide a highly reliable lead-acid battery that suppresses deterioration and breakage of the bottom of a U-shaped glass mat used together with a bag-shaped separator and prevents an internal short circuit. [Structure] A U-shaped glass mat 2 is arranged on the inner surface of a separator 1 made of a microporous polyethylene film, and a reinforcing tape made of a fluororesin is attached to reinforce the bottom bent portion of the glass mat 2 to reinforce the bag-shaped separator. Is wrapped around the positive electrode plate 4.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bag-shaped separator for a lead storage battery.

[0002]

2. Description of the Related Art Heretofore, in lead acid batteries, the paste-like active material has fallen off from the grid body due to corrosion and deformation of the grid body as it is used, and volume change of the active material itself due to charging and discharging.

Therefore, in order to prevent the active material from falling out of the lattice, a flat plate-shaped separating member in which a glass mat containing glass fiber as a main component and a separator containing pulp as a main component are combined is used. However, in this configuration, the electrode plate and the separating member are not displaced, and the active material cannot be sufficiently prevented from falling out of the lattice body, so that the short circuit at the lower part of the electrode plate is not sufficiently prevented.

In order to improve the problem, a method of wrapping the electrode plate with a microporous film separator containing polyethylene and silica as main components and molded in a bag shape was adopted, and the above problems were solved.

However, even under the use conditions involving relatively deep charging and discharging, there have been some cases in which the paste-like active material is not sufficiently retained by the lattice and falls off. In addition, when used at high temperature and with a slight tendency to overcharge, the positive electrode plate may be bent or deformed, and the lower part of the bag-shaped separator may be broken and short-circuited. For this reason, in order to hold down the paste-like active material and prevent the polyethylene separator from malfunctioning, a combination type separator in which a glass mat is superposed on the inside of the bag-like polyethylene separator has come to be used.

[0006]

In recent years, the engine room of automobiles has become extremely hot due to the mounting of high-performance engines and the compact body shape, and lead acid batteries are used under such high temperature conditions. Then, the corrosion of the positive electrode grid proceeds, causing the grid to deform. As a result, the separator was broken and short-circuited due to the bite of the frame bone on the lattice side. However, the short circuit was prevented by using the glass mat together.

However, the glass mat is very fragile against bending, and the one enclosing the lattice in a U shape at the time of manufacturing the battery sometimes breaks completely at the bottom bent portion during use. For this reason, since the positive electrode plate and the polyethylene separator are in direct contact with each other at the bottom of the positive electrode grid, a new problem arises that the grid bone breaks through the separator and short-circuits with the negative electrode.

It is an object of the present invention to provide a highly reliable lead storage battery which suppresses the deterioration of the glass mat at the bottom bent portion of the bag-shaped separator to prevent a short circuit.

[0009]

To achieve the above object, the present invention provides a bag-shaped separator comprising an electrode plate having a grid coated with a paste-like active material and a microporous synthetic resin film surrounding the electrode plate. And a U-shaped glass mat disposed between the electrode plate and the separator, and a reinforcing member is provided at least in the bent portion of the glass mat. The reinforcing member is an acid resistant material, preferably a fluororesin or a tape thereof.

[0010]

According to the present invention, the U-shaped glass mat is prevented from being broken by the reinforcement of the bottom bent portion thereof due to the above-mentioned construction, and the expanded and deformed lattice bone breaks the separator outside the bent portion of the mat. Can be prevented, and an internal short circuit due to contact with the counter electrode can be prevented.

[0011]

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a view showing the structure of the positive electrode plate and the bag-shaped separator of this embodiment. A U-shaped glass mat is formed on the inner surface of a microporous bag-shaped film separator 1 mainly composed of polyethylene and silica. 2 is arranged, and a tape made of fluororesin having a width of 40 mm is attached around the bottom bent portion. The positive electrode plate 4 is wrapped with this bag-shaped separator.

FIG. 2 is a sectional view showing the structure of the positive electrode plate and the separator of this embodiment, showing the arrangement of tapes made of fluororesin. As is clear from this figure, the tape 3 made of fluororesin as a reinforcing member is arranged between the bag-shaped separator 1 and the U-shaped glass mat 2. As a result, the influence of expansion and deformation of the positive electrode plate 4 due to charging and discharging is absorbed by the glass mat 2 and the tape 3, and the separator 1 and the positive electrode plate 4 do not come into direct contact with each other.

FIG. 3 shows the results of a comparative study of the lead-acid battery A of the present embodiment and the conventional example B which does not include the tape 3 made of fluororesin, both having a 12 V specification and a nominal capacity of 48 Ah.

FIG. 3 is a diagram showing the relationship between the number of life cycles and the voltage at the 30th second in the SAE pattern at 75 ° C.

As is apparent from FIG. 3, the conventional battery B is used.
In contrast, in the middle of the test, the voltage drastically decreases and reaches the end of its life, whereas in the battery A of this example, the voltage gradually decreases and reaches the end of its life.

Then, each battery which had reached the end of its life was disassembled, and the cause of the life was examined. As a result, in the battery of B, the grid of the positive electrode broke through the separator at the bottom of the separator and contacted the negative electrode to cause a short circuit, resulting in the end of life. . On the other hand, in the battery A, the phenomenon that the bottom of the separator broke through and the internal short circuit was not observed, and the life of the battery was deteriorated due to deterioration of the lattice itself.

[0018]

As is apparent from the above description, according to the present invention, a combined type separator in which a U-shaped glass mat whose bent portion is reinforced with a reinforcing member and a bag-shaped separator are superposed is used. Therefore, it is possible to provide the lead storage battery in which the glass mat is not deteriorated or cut at the bent portion at the bottom thereof and the internal short circuit does not occur due to the breakage of the separator.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a configuration of a positive electrode plate wrapped with a bag-shaped separator of a lead storage battery according to an embodiment of the present invention.

FIG. 2 is a sectional view showing the structure of the positive electrode plate.

FIG. 3 is a diagram showing the relationship between the number of life cycles and the voltage at the 30th second of the battery in the example of the present invention and the conventional example.

[Explanation of symbols]

 1 Film Separator 2 Glass Mat 3 Tape Made of Fluorine Resin 4 Positive Plate

Claims (2)

[Claims] 1. An electrode plate in which a grid is coated with an active material, a bag-shaped separator made of a microporous synthetic resin film surrounding the electrode plate, and a U-shaped glass disposed between the electrode plate and the separator. A lead-acid battery, comprising a mat, and an acid-resistant reinforcing member provided at least on a bottom bent portion of the bag-shaped glass mat. 2. The lead acid battery according to claim 1, wherein the reinforcing member is a fluororesin or a tape thereof.