JPS5951713B2 - sealed lead acid battery - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a so-called cage-type sealed lead-acid battery having a structure in which an electrolyte is held between positive and negative electrode plates and a separator.

The drawback of this type of battery A is that, as shown in FIG. 1, its high rate discharge performance is inferior to that of the battery B of the same type, which has a sufficient amount of electrolyte. The cause of this is the non-uniform distribution of the electrolyte.

In battery B, there is a sufficient amount of fluid electrolyte, so the electrolyte is evenly distributed, but in battery A, only the positive and negative electrode active materials and the separator are impregnated with and retained electrolyte. Therefore, it is affected by wetting with the electrolyte.

That is, since the positive and negative electrode active materials are inferior in hydrophilicity (electrolyte-philicity) compared to the separator, such as glass wool, the electrolyte is present in a large amount in the separator and in a small amount in the positive and negative electrode plates. In high-rate discharge, only the electrolyte inside and near the electrode plates is used, so batteries with a small amount of electrolyte in the plates, such as cage-type batteries, are disadvantageous, and the high-rate discharge performance of these batteries is affected by fluid electrolysis. This is the reason why the batteries are inferior to batteries with sufficient liquid. The present invention eliminates these drawbacks and provides a sealed lead-acid retainer battery with excellent high-rate discharge performance.

The gist thereof is to mix 0.5 to 10.0 weight percent of hollow short glass fibers into the positive and negative electrode active materials. Hollow short glass fibers are open at both ends and can hold dilute sulfur inside the hollow, so if they exist in the positive and negative electrode active materials in this state, they can improve the high rate discharge performance of retainer batteries. It is effective for In other words, during high-rate discharge, the concentration of the electrolyte in the electrode plate decreases, but if short glass fibers containing dilute sulfuric acid are present in the active material inside the hollow, the dilute sulfuric acid will diffuse out of the hollow due to the concentration difference. Since the sulfuric acid content is supplied by
Superior high rate discharge compared to conventional retainer batteries.

Next, the present invention will be explained using examples. Nominal capacity (2
0hR) 7Ah retainer type sealed lead acid battery,
The positive and negative electrode active materials each have FL&; hollow glass short fibers of 0.
The low temperature high rate discharge performance (28A
discharge, -1°C).

The results are shown in Table 1. As is clear from Table 1, as the number of hollow short glass fibers in the positive and negative electrode active materials increased, the high rate discharge performance improved.

However, when the amount added is 15.0% by weight, 0.5
The weight percentage was lower than that of the weight percentage. This is because the bonds between the active materials are broken due to the large amount added.
Therefore, the amount added is from 0.5% by weight to 10.0% by weight.
should be in the weight percent range. Note that if the amount added is less than 0.5 weight percent, the effect of the addition will not be sufficiently obtained. Further, the hollow short glass fibers used in the present invention are preferable in terms of wettability with the electrolytic solution, and can retain the electrolytic solution well in the hollow space and allow the electrolytic solution to seep out from the hollow space well. Further, the hollow short glass fibers 2 are preferably added by dispersing them in dilute sulfuric acid added when kneading the raw materials for the positive and negative electrode plates. For this reason, impregnating the hollow glass short fibers with dilute sulfuric acid in advance is superior in terms of ease of impregnation. That is, when dilute sulfuric acid is impregnated into the hollows of the short glass fibers present in the active material by injecting the electrolytic solution, there is a risk that all the short glass fibers will not be uniformly impregnated. It is also conceivable to add microscopic hollow bodies with a large number of holes in the walls of a complicated shape such as a cavernous shape to the active material, and to have the electrolyte held in the microscopic hollow bodies. In a hollow body, the path for the electrolytic solution contained in the hollow body to seep out to the outside is complicated, so that it is difficult to seep out from the hollow body to the outside, and a sufficient effect cannot be obtained.

However, the hollow short glass fiber used in the present invention is formed with a hollow concentric with the fiber diameter and along the length of the fiber, so the shape of the hollow is simple, and the electrolyte within the hollow is subject to a concentration gradient. Therefore, it can easily seep out from inside the hollow to the outside, and a sufficient effect can be exerted. As mentioned above, in a so-called retainer type lead-acid battery in which the electrolyte is impregnated and held in the positive and negative electrode active materials and the separator, high rate discharge performance can be improved by adding hollow glass short fibers to the positive and negative electrode active materials. Although it was very effective for improvement, even when added to a lead-acid battery with a sufficient amount of flowing electrolyte, the high rate discharge performance was slightly better compared to a battery without the addition due to the large amount of sulfuric acid near the electrode plates. .

As described above, by adding hollow short glass fibers to the active material of a lead-acid battery, high rate discharge performance is improved, and this has great industrial value.

[Brief explanation of the drawing]

Figure 1 shows that the high rate discharge performance of so-called retainer type lead-acid batteries, which have a structure in which positive and negative electrode active materials and separators are impregnated with and retained electrolyte, is inferior to that of lead-acid batteries that have a sufficient amount of electrolyte. show.

Claims (1)

[Claims] 1. A lead-acid battery having a structure in which an electrolyte is impregnated and held in the positive and negative electrode plates and a separator, characterized in that 0.5 to 10.0 weight percent of hollow short glass fibers are added to the positive and negative electrode plate active materials. A sealed lead-acid battery.