JPH06196142A - Lead-acid battery - Google Patents

Abstract

PURPOSE:To prevent short-circuit of a lower part, and to stabilize the quality at a low cost by using an isolator, in which, a glass mat and a separator are stuck together at their lower parts across a predetermined length by means of acidproof, oxidation-resistant resin or an acidproof, oxidation-resistant adhe sive. CONSTITUTION:An isolator 6 is used, in which, a glass mat 2 and a separator 1 are stuck together at theier lower end parts, by means of an acidproof, oxidation-resistant resin or an acidproof, oxidation-resistant adhesive at least across a distance larger than the length of the leg of a negative electrode plate 5. For example, the separator 1 and the glass mat 2 are superimposed on each other so that a superimposed part 3 by a hot-melt resin of polypropylene comes right befow the battery, and this is cut into a predetermined size. The size of the vertical width of the part 3 is 5mm, which is 2mm longer than that of the lef of the plate 5, and a depositin liquid for the separator 1 and the glass mat 2 is largely compressed at its glass mat 2 side at the time of deposition. Short-circuit at the lower part can be prevented by using such an isolator 6, and the quality can be stabilized at a low cost.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to improvements in lead acid batteries.

[0002]

2. Description of the Related Art Lead acid batteries are currently used for automobiles,
Widely used in all fields including industrial use. Among them, automobile batteries are the most in demand, lighter weight,
Cost reduction, maintenance-free operation, long life, and stable quality are required.

However, automobile batteries have many life modes, and in particular, short circuits cause a short life, which is a major problem in terms of prolonging service life and stabilizing quality. In particular, a short circuit at the bottom of the electrode plate is a problem.

This is because the particles of lead dioxide, which is the positive electrode active material that has fallen off from the electrode plate due to repeated charging and discharging, vibration of the vehicle, and the like, floats up due to convection of the electrolytic solution and accumulates on the legs of the negative electrode plate. It is considered that this is caused by reduction and growth as metallic lead, and contact with the lower lattice portion of the positive electrode plate.

At present, the mainstream of separators used mainly in products is a glass mat and a separator substrate (for example, a paper product of inorganic powder and fibers) bonded to each other. Lead metal is particularly prone to grow in the spaces between the fibers in the glass mat. Therefore, this separator does not play a role in preventing the short circuit around the electrode plate.

Various methods have been proposed and various proposals have been made as a method for preventing a short circuit occurring around the electrode plate. Among them, many patents for devised separators have been filed and put into practical use.

[0007] One of them is one in which a negative electrode plate or a positive electrode plate is wrapped in a bag-shaped separator to prevent a short circuit, which is already in practical use. In this method, however, the electrode plate is a bag-shaped separator. The wrapping process is difficult, and the electrode plate group is much more difficult to manufacture than the one using a separator in which a glass mat and a separator are laminated. Further, the cost of the bag-shaped separator itself is higher than that of the separator in which the glass mat and the separator are bonded together.

In a separator in which a glass mat and a separator are bonded together, in JP-A-58-129746, the lower part of the glass mat of the separator is removed, and the removed portion is made of the same material as the separator and the same thickness as the glass mat. It has been proposed that a lower short circuit is prevented by using a separator to which the object is attached. Further, it has been found that if the peripheral portion of the glass mat is made smaller than the separator by several millimeters, it becomes difficult for a short circuit to occur in the peripheral portion of the electrode plate, and it has already been put to practical use in some lead-acid batteries for electric vehicles.

However, all of these methods have drawbacks that they are difficult to manufacture and are expensive.

[0010]

DISCLOSURE OF THE INVENTION The present invention eliminates the above-mentioned drawbacks by providing a glass mat and a separator at the lower edge thereof at least for the length of the legs of the negative electrode plate, an acid-resistant, oxidation-resistant resin or By using a separator bonded with an acid-resistant and oxidation-resistant adhesive, it is possible to easily and inexpensively manufacture a separator that can prevent short circuits, especially lower short circuits, and use it in lead-acid batteries. As a result, it is possible to provide a lead storage battery in which a short circuit, especially a lower short circuit, is unlikely to occur.

[0011]

EXAMPLES The present invention will be described below based on examples.

According to the conventional method, four positive electrode plates per cell,
Automotive lead-acid battery with 5 negative plates (nominal capacity 28 Ah,
The electrode plate group (5 hour rate) was laminated and arranged. Generally, there are two types of alloys for the positive electrode plate grid, a lead-calcium alloy and a lead-antimony alloy. Here, for both alloys, those having the composition used in a normal lead-acid battery are used. Two kinds of electrode plate groups were manufactured using a positive electrode plate using a lead-calcium alloy in a positive electrode plate grid and a positive electrode plate using a lead-antimony alloy in a positive electrode plate grid. The separator of the present invention was inserted between the positive electrode plate and the negative electrode plate to prevent a short circuit.

For comparison, a separator, which is used in an ordinary lead-acid battery and has a separator and a glass mat bonded together, is inserted between the positive electrode plate and the negative electrode plate, and
A group of electrode plates was prepared. Using these electrode plates, a 12V liquid lead acid battery for automobiles was manufactured by a conventional method.

FIG. 1 is a schematic view of a separator used in the battery of the present invention. As the separator, a separator 1 formed by wet-paper-making inorganic powder, inorganic fibers and organic fibers with a small amount of a binder to form a sheet, and a glass mat 2 made of glass fibers having a fiber diameter of 13 μm are hot-melted with polypropylene. The resin-bonded portion 3 was bonded so that it would come to the bottom of the battery, and cut into a predetermined size. The vertical width of the glued part is 2 mm from the length of the negative electrode plate.
It is 5 mm long. In the welded portion of the separator and the glass mat, the glass mat side is largely compressed during welding.

FIG. 2 is a schematic view showing an embodiment of the lead acid battery of the present invention. Reference numeral 4 is a positive electrode plate, 6 is a separator for the battery of the present invention inserted between the positive electrode plate and the negative electrode plate, and 5 is a negative electrode plate. Since the assembly of the electrode plates is generally laminated so that the glass mat side of the separator comes into contact with the positive electrode plate surface, a space corresponding to the compressed glass mat is formed at the lower end of the positive electrode plate as shown in the figure. This is convenient for preventing short circuits.

Next, the result of the life test of the liquid lead acid battery according to the present invention will be described. The battery used for the test is a 12V automotive liquid lead-acid battery with a nominal capacity of 28Ah. Table 1 shows the contents of the test battery.

[0017]

[Table 1]

Batteries No. 1 and 2 are batteries of the present invention using a separator with only the lower part adhered, and batteries No. 3 and 4 are
This is a conventional battery using a separator in which only both sides are adhered.

A capacity test was conducted to investigate whether the separator of the present invention adversely affects the battery performance. Two
The discharge capacity at 5 ° C. and 5 A and the discharge capacity at −15 ° C. and 150 A were examined. The results are shown in Table 2.

[0020]

[Table 2]

Batteries No. 1 and 2 using the separator of the present invention
There was no difference in capacity between the batteries No. 3 and 4 using the conventional separator.

Next, the life performance was evaluated by the JIS D5301 heavy load life test.

The discharge current is 20 A, the charge current is 5 A, and the test temperature is 42.5 ± 2.5 ° C. The results are shown in Fig. 3.

The battery No. 3 using the separator of the conventional product and using the lead-calcium alloy for the positive electrode grid has a life of 70 cycles, while the separator of the invention is used, and The battery No. 1, which uses a lead-calcium alloy for the positive electrode grid, has a life of 180 cycles, which is more than twice as long as that of the battery using the conventional separator. When disassembling the battery to investigate the cause of life, No. 3
The product using the conventional separator of (3) had a life due to a lower short circuit.

On the other hand, in the case where the product of the present invention of No. 1 is used, the softening of the active material and the corrosion layer formed at the active material-lattice interface are preferentially discharged over the active material. The active layer, which is the so-called barrier layer, has reached the end of its life, and short circuits have hardly occurred.

A battery using a conventional separator and a lead-antimony alloy for the positive electrode grid, No. 4, is 3
In contrast to 30 cycles of life, the battery using the separator of the present invention and using the lead-antimony alloy in the positive electrode grid, No. 2, has a life of 450 cycles, which is the conventional separator. The life performance was about 1.4 times higher than that of the product using.

When the battery was disassembled to investigate the cause of the life, the battery using the conventional separator of No. 4 had a life due to the lower short circuit. On the other hand, in the case of using the product of the present invention of No. 2, the service life was shortened due to the softening and dropping of the active material, and the short circuit hardly occurred.

Incidentally, a separator having the lower part and both side parts, a part of the lower part (negative electrode plate foot part) and both side parts, and the peripheral part adhered was prepared, and using these, a battery having the same structure was prepared, When the same test was performed, all showed good life performance.

When the battery was disassembled for the purpose of investigating the cause of the service life, the battery using the product of the present invention had a service life due to the softening and dropping of the active material, and a short circuit hardly occurred.

[0030]

As is apparent from the above-described embodiments, the present invention provides a glass mat and a separator at the lower edge thereof at least over the length of the legs of the negative electrode plate, the acid-resistant and oxidation-resistant resin or By using a separator bonded with an acid-resistant and oxidation-resistant adhesive, it is possible to easily and inexpensively manufacture a separator that can prevent short circuits, especially lower short circuits, and use it in lead-acid batteries. By
Short circuit, especially bottom short circuit, is extremely unlikely to cause lifespan, so lifespan performance is improved, product quality is stabilized, and cost is lower than conventional lead-acid batteries using short-circuit prevention separators. And its industrial value is enormous.

[Brief description of drawings]

FIG. 1 is a schematic view of a separator used in the battery of the present invention.

FIG. 2 is a schematic view showing an embodiment of the lead acid battery of the present invention.

FIG. 3 is a diagram showing a life test result.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Separator 2 Glass mat 3 Hot melt welding part 4 Positive electrode plate 5 Negative electrode plate 6 Separator 7 Pole 8 Connection part between cells 9 Battery case

Claims (1)

[Claims] 1. A separator in which a glass mat and a separator are bonded at their lower edges by at least the foot length of the negative electrode plate with an acid-resistant, oxidation-resistant resin or an acid-resistant, oxidation-resistant adhesive. Lead acid battery characterized by being used.