JPH0448550A - Sealed lead-acid battery - Google Patents

Abstract

PURPOSE:To improve high-rate discharge characteristics by mainly mixing acid-resistant inorganic powder and fibers, then using a porous body mechanically bent and applied with elasticity for an electrolyte holder. CONSTITUTION:Polyester fibers 15wt.% with the length about 100mm and the diameter 0.5 denier and glass fibers 15wt.% with the length 0.7mum and powder silica silicate 70wt.% are dispersed in water, an adsorbent and a small quantity of a binder are put in them so that powder is adsorbed to the polyester fibers and glass fibers, and it is mixed and dried to form a mat-shaped separator with the thickness about 1.5mm. The silica powder with the second or third grain size 20mum or below normally used is utilized here. Elasticity is applied to the above separator with an elasticity machining device.

Description

[Detailed description of the invention] Industrial applications The present invention relates to improvements in sealed lead-acid batteries.

Conventional technology and its problems There are two types of sealed lead-acid batteries, the retainer type and the gel type, in which the negative electrode absorbs oxygen gas generated during battery charging. The retainer type inserts a matte separator (glass separator) made of fine glass fiber between the positive and negative electrode plates, which holds the sulfuric acid electrolyte necessary for discharge and isolates the two electrodes. In recent years, it has become widely used as a backup power source for portable devices and computers. However, the glass separator in the retainer type is expensive, which is a hindrance to this type of sealed battery.

On the other hand, although the gel type is cheaper than the retainer type, it has the disadvantage that its battery performance is inferior to the liquid type and retainer type.

As a method of reducing the cost of the mat-like separator used in the retainer-type button storage battery mentioned above, JP-A-1-2! +
As shown in No. 3153 and Japanese Unexamined Patent Publication No. 59-105263, a method using a comparatively inexpensive mixed paper of acid-resistant inorganic powder and fibrous material has been proposed. However, when the proportion of acid-resistant inorganic powder in this mat-like separator is low, the pore size tends to increase, resulting in poor electrolyte retention ability, resulting in poor battery performance, and furthermore, there is a risk of separator penetration short circuit during use. There is sex. However, when the amount of acid-resistant inorganic powder is increased, the mat-like separator after papermaking becomes hard and its adhesion to the electrode plate deteriorates, resulting in a disadvantage that the battery performance is degraded. In addition, the acid-resistant inorganic powder used for these mixed papermaking processes generally uses inexpensive particles with a particle size of 50 μm or less. It was even thought that the pore size would become too large to be suitable for use as a separator.

Means for Solving the Problems The present invention solves the problems of the conventional sealed lead-acid batteries mentioned above. In lead-acid batteries, a mat-like separator made of a mixture of acid-resistant inorganic powder and fibers and then mechanically bent to give elasticity is used as an electrolyte holding body, which allows for close contact with the electrode plates. The objective is to provide a separator with high properties and improve battery performance.

Example Hereinafter, this defense will be explained in detail with reference to Examples.

First, the production of the mat-like separator used as the electrolyte holder of the battery of the present invention will be explained.

Polyester fibers with a length of about 1011 and 1a fiber diameter of 0.5 denier and 0.7μ chicken glass fibers are each dispersed at 15 wt% and silicic acid powder (silica) at 70 wt% in water, and then adsorbent and A small amount of binder is added to make the powder adsorbed onto polyester fibers and glass fibers, and a mat separator with a thickness of approximately 1.5I1m is produced by papermaking and drying.
A commonly used particle having a secondary particle size of 20 μm or less was used.

Next, elasticity was imparted to the separator using an elasticity processing apparatus shown in FIG. To explain this device here, FIG. 1 is a front view of the main part of the device, in which a pair of rotating gears 1 mesh with each other at a constant interval. The width of the gear was set to be large enough to uniformly process the separator over the entire surface of the separator, ie, slightly larger than the length of the separator. The above-mentioned separator 2 was inserted into the gap between the pair of gears from one side, and was removed from the other side in response to the gears. When this operation is repeated several times by changing the direction of the separator to be inserted, mechanical bending is applied to the separator, so that the bonds between the fibers bonded with the binder are loosened appropriately, and the apparent thickness of the separator is smaller than that of the separator before using the device. A mat-like separator was obtained that was flexible and elastic.

A sealed lead-acid battery N0 of a retainer type with different degrees of compression of the electrode plate group using the separator produced by the method described above.
91-5 was produced. For comparison, conventional sealed lead-acid batteries Nos. 016 to 10 were also produced using a mat-like separator without using an elastic processing device after papermaking. The battery manufactured here has a nominal capacity of 4.5 h. The test results are shown in Table 1.

From this test result, batteries using separators that were elastically processed after papermaking (No. 1 to 5) were compared to conventional products (No. 6).
-10) No difference was observed in 5hR capacity, and the capacity was 6 to 52% larger in high rate discharge.

The reason why there was no difference in the 5hR capacity was because there was no difference in the amount of electrolyte held in the separator, and the reason why the high rate discharge capacity was large was because the electrolyte retainer was made elastic by adding elasticity to the separator according to the present invention. This is probably because the adhesion between a certain separator and the positive and negative electrode plates was much better than that of conventional products.

Table 1 In particular, in conventional products, when the degree of compression of the electrode plate group was less than 50 IJ/tM, the high rate capacity decreased significantly, but such a phenomenon was not observed in the batteries according to the present invention.

This is also due to the fact that elasticity is imparted to the separator according to the present invention, which improves the adhesion between the separator and the positive and negative electrode plates. It is judged that there is no need to increase adhesion by creating a

Effects of the Invention As detailed above, the sealed Ofuna storage battery according to the present invention has the following effects:
By using a porous body made of a mixture of acid-resistant inorganic powder and fibers and then mechanically bent to give elasticity as an electrolyte holder, it has great industrial value, such as improving high-rate discharge characteristics.

[Brief explanation of the drawing]

FIG. 1 is a front view of main parts showing an outline of the elastic processing device. 1...Gear, 2...Separator

Claims (1)

[Claims] 1. A sealed lead-acid battery characterized in that a porous body made of a mixture of acid-resistant inorganic powder and fibers and then mechanically bent to give elasticity is used as an electrolyte holder.