JPH04118854A - Gel type lead storage battery - Google Patents

Abstract

PURPOSE:To improve the high rate discharge property and the service life of a battery and to reduce the cost by using a separator manufactured by mixing an acidproof inorganic powder and a synthetic fiber. CONSTITUTION:A substance formed by mixing an acidproof inorganic powder and a synthetic fiber, mixing 30wt.% of polyester powder with the fiber diameter 0.5 denier, and 70wt.% of silica powder, for example, is disposed in the water. Then, an adsorbent and a small amount of binder are entered therein to absorb the powder to the polyester fiber, and it is formed to sheet and dried to obtain a mixture sheet of separator. By using such a mixture sheet of separator, a gel type battery to which a dilute sulfric acid including 7% of colloidal silica is poured is produced. This battery has not only an excellent high rate capacity, but also the service life is extended two times.

Description

[Detailed description of the invention] Industrial applications The present invention relates to improvements in gel type 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 Ha 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 of the retainer type is expensive, which is an obstacle to the widespread use of 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 high rate discharge performance and life performance are inferior to the liquid type and retainer type.

In gel batteries, the electrolyte is non-fluid due to gelation, so the diffusion rate of sulfate ions in the electrolyte is slow, and it is thought that the high rate discharge capacity, which is limited by the diffusion rate of sulfate ions, is inferior. It will be done. In addition, with gel batteries,
As charging and discharging are repeated, water (H2O) is gradually lost and cracks occur in the gel electrolyte, which liberates the electrolyte. This liberated electrolyte accumulates at the bottom, and as a result, the electrode plate The lower part is preferentially charged and discharged, and the deterioration of the lower part of the electrode plate is accelerated. It is presumed that once the active material deteriorates in the lower part, the charging and discharging reactions will then concentrate in the upper part of the electrode plate, accelerating the deterioration in this part and ending the life of the battery.

Means for Solving the Problems The present invention solves the above-mentioned problems of conventional gel-type lead-acid batteries. By using separators made by mixing acid-resistant inorganic powder and synthetic fibers (hereinafter referred to as mixed paper separators) instead of resin or valve separators, we can lower the electrical resistance of the separators and improve high-rate discharge performance. The aim is to improve battery life by simultaneously making the charging and discharging reactions more uniform.

Example The present invention will be explained in detail below with reference to Examples.

First, the mixed paper separator used as the separator of the battery of the present invention will be explained. Length approx. 101° Fiber diameter 0.5
Disperse 30wt% of denier polyester fiber and 70wt% of silica powder in water, then add an adsorbent and a small amount of binder to make the powder adsorb to the polyester fiber, form a paper, and dry it to a thickness of about 1.2mm. A mixed paper separator was produced. The silica powder used here was a commonly used silica powder having secondary particles or tertiary particles of 20 μm or less.

Using the mixed paper separator produced by this method, dilute sulfuric acid containing 7% colloidal silica was injected into an electrolytic solution with a specific gravity of 1.
Thirty gel type batteries A were produced. For comparison, a gel type battery B was produced using a flat pulp separator of the same thickness (1,211 nm thick).

The nominal capacity of the battery produced here is 5hR capacity and 28^h
This is a sealed lead-acid battery for automobiles. After the initial capacity test, batteries A and B were subjected to a JIS life test for automobile batteries, and the life span was defined as the number of cycles at which the discharge capacity reached 70% of the standard value. The results are shown in Table 1.

Table 1 From the results in Table 1, battery A using a mixed paper mat as a separator is different from battery B using a conventional valve separator.
Although the 5hR capacity is almost the same as that of the previous model, not only is the high rate capacity superior, but the JIS life span has doubled from 200 to 400.

The reason for this is that although the electrolyte is in a gel state, the diffusion rate of sulfate ions remains the same, but compared to valve separators, the mixed mat used this time has a lower electrical resistance and a lower voltage drop during high-rate discharge. As a result, it seems that the high-rate capacity was excellent. In addition, the free liquid generated when a gel type lead-acid battery is charged and discharged is also absorbed by the mixed mat because the absorbency of the mixed paper mat is superior to that of valve separators, etc. This is thought to be the reason for the long lifespan due to the fact that the deterioration of the active material is gradual, as the deterioration of the active material is performed uniformly without being locally concentrated.

Note that the mixed mat is cheaper than the glass separator used in caged lead-acid batteries, and is superior to the glass separator in terms of cost.

Effects of the Invention As detailed above, the gel type lead-acid battery according to the present invention improves high rate discharge performance and battery life by using a separator made by mixing acid-resistant inorganic powder and synthetic fiber. It is also cheaper in terms of connectivity than glass separators, and its industrial value is great.

Claims (1)

[Claims] 1. A gel type lead-acid battery that uses a separator made from a mixture of acid-resistant inorganic powder and synthetic fiber.