JPH03246871A - Manufacture of sealed lead-acid battery - Google Patents

Abstract

PURPOSE:To shorten the injection time of a sulfuric acid electrolyte by injecting a smaller quantity of the low-specific gravity sulfuric acid electrolyte than that which can be held by a positive electrode plate, a negative electrode plate and granular powder for the formation of an electrode plate group, then injecting a high-specific gravity sulfuric acid electrolyte to obtain the preset electrolyte quantity and electrolyte specific gravity. CONSTITUTION:Normal positive electrode paste and negative electrode paste are filled in positive and negative electrode lattices and aged, then they are inserted into a battery jar. The silica granular powder manufactured by adding water to silica fine powder into a paste shape and drying and crushing it is densely filled between both electrodes and around an electrode plate group while vibrations are applied. A sulfuric acid electrolyte is injected with the preset specific gravity and injection factor to a battery thus assembled for formation. The specific gravity of the sulfuric acid electrolyte is determined from the battery voltage after formation is completed end the battery is left intact for a preset period, the sulfuric acid electrolyte is supplemented in consideration of the decreased quantity of the battery weight during formation, and the specific gravity is adjusted to a preset value. No gap is generated inside the silica granular powder, and the injection time of the sulfuric acid electrolyte can be largely shortened.

Description

DETAILED DESCRIPTION OF THE INVENTION FIELD OF INDUSTRIAL APPLICATION This invention relates to an improvement in the manufacturing method of sealed lead-acid batteries.

BACKGROUND OF THE INVENTION In recent years, sealed lead-acid batteries have come into widespread use as power sources for portable devices and computers. This type of sealed lead-acid battery is classified into a retainer type and a gel type depending on the electrolyte retention method. The retainer type is a method in which the 8 Ta acid electrolyte is held in a porous separator made from la fine glass fiber, and the gel type is a method in which the 8 Ta acid electrolyte is turned into a gel using silicic acid and filled into the battery. This is the way to do it.

Problems to be Solved by the Invention In the case of a retainer type separator, the fine glass fibers that make up the main body of the separator are expensive, so the separator itself is also very expensive. For this purpose, separators replaced with synthetic resin m-fibers have been developed, but they do not have sufficient liquid retention properties.

On the other hand, in the case of a gel type, preparing and filling the gel is complicated, and since it is necessary to fill all spaces except the space above the element with gel, there is a drawback that extra electrolyte must be filled. Ta.

Furthermore, due to the slow diffusion of VA acid ions within the gel, the performance was inferior to conventional open-type liquid lead-acid batteries as well as retainer-type sealed lead-acid batteries.

Closed type to solve these problems! We investigated silica granulated powder as an electrolyte retaining material for storage batteries, and found that silica granulated powder can be used as an electrolyte retaining material. However, as the experiments progressed, several shortcomings became apparent. As one of these methods, when forming the electrode plates in the battery case, the gas generated during forming pushes up the silica granulated powder along with the electrolyte, filling the gap between the positive and negative electrode plates. It was found that voids were created that did not contribute to the charging and discharging of the battery.

Means for Solving the Problems The present invention provides a sealed lead-acid battery using silica granulated powder, which is an electrolyte retainer for a sealed lead-acid battery that is inexpensive and has excellent liquid retention and sulfuric acid diffusivity. This solution solves the above-mentioned problems, and its gist is to inject a smaller amount of low-density sulfuric acid electrolyte than can be held in the positive and negative electrode plates and the above-mentioned granulated powder to chemically form the electrode plate group. After that, a high specific gravity sulfuric acid electrolyte is injected to adjust the electrolyte amount and electrolyte specific gravity to a predetermined value. This will be explained in detail in Examples below.

Example After filling the positive and negative electrode grids made of Pb-Ca-3n alloy with ordinary positive and negative electrode pastes and aging them, a group of electrode plates was prepared with three positive electrode plates and four negative electrode plates, and the plates were placed in a battery case. Inserted. Here, the gap between the two electrodes was maintained using a synthetic resin plate having a thickness of approximately 1.5111 mm, but any material may be used as long as it is harmless to the battery and can maintain the gap between the two electrodes. It is preferable to use a material that occupies a small volume between the two electrode plates.

Next, add water to the fine silica powder and make it into a paste for about 2
Diameter 20-500 made by drying at 00℃ and then crushing
Granulated silica powder of μm size was densely packed between the two electrodes and around the electrode plate group while applying vibration. The silica granulated powder filled here is about 90% in the filled state, and about 85% by itself.
% porosity.

After filling the granulated powder in this manner, a lid was adhered and an exhaust valve was attached to assemble a sealed lead-acid battery having a nominal capacity of 4.5 Ah. Chemical formation was performed by injecting sulfuric acid electrolyte into the thus assembled battery at the specific gravity and injection rate shown in Table 1.

Table 1 Here, the injection rate is the amount of sulfuric acid electrolyte injected relative to the amount of sulfuric acid electrolyte that can be held in the bipolar plates and the silica granulated powder, which is determined from the porosity of the bipolar plates and the porosity of the filled silica granulated powder. V
This is the ratio of the X-acid electrolyte, and an injection rate of 100% indicates that exactly the amount of sulfuric acid electrolyte that can be held in the bipolar plates and the silica granulated powder has been injected. 300% of the theoretical amount of electricity was applied to the positive electrode active material over a period of 20 hours.

When we observed the batteries during chemical formation, we found that in batteries 1, 2, 5, 6 and 9 where the injection rate was 100% or more, the electrolyte was extruded onto the top of the filled silica granulated powder, and the filled silica Voids were observed inside the granulated powder. This is because, as mentioned above, the electrolyte is pushed out from inside the electrode plate by the gas generated during charging, and the electrolyte fills the pores of the silica granules all at once, making it difficult for gas to escape. It is thought that the voids are created because there is no path and the gas comes out to the top of the battery while pushing the silica granulated powder.

On the other hand, in batteries where the injection rate was less than 100%, no electrolytic solution was observed above the filled silica granulated powder, and no voids were present inside the filled silica granulated powder. Furthermore, when injecting the sulfuric acid electrolyte, the production method according to the present invention has the effect that the injection time for the sulfuric acid electrolyte, which normally takes a long time, can be significantly shortened because the amount of sulfuric acid electrolyte to be injected is small. Ta.

After chemical formation is completed, the specific gravity of the sulfuric acid electrolyte is determined from the battery voltage after being left for 24 hours, and the sulfuric acid electrolyte is supplemented taking into consideration the amount of decrease in battery weight during chemical formation, and the specific gravity of the sulfuric acid electrolyte is adjusted to 1.
30, and the amount of electrolyte was adjusted to just the amount that could be held in both electrode plates and silica granulated powder. Thereafter, supplementary charging was performed for 4 hours at 0.45 A to make the electrolyte in the battery sufficiently uniform. Here, the specific gravity is 1.0
In battery 1, in which the sulfuric acid electrolyte of No. 5 was injected at a injection rate of 110%, the amount of electrolyte after formation matched the amount of sulfuric acid electrolyte that could be held in the bipolar plates and the silica granulated powder, so a high concentration sulfuric acid electrolyte was used. could not be injected. Specific gravity 1.2
Battery 9, in which the sulfuric acid electrolyte of No. 5 was injected at an injection rate of 110%, has a specific gravity of 1.30 after formation, and the amount of electrolyte exactly matches the amount of sulfuric acid electrolyte that can be held in the bipolar plates and the silica granulated powder. This is a battery prepared using a conventional method. In addition, for batteries 2 and 6 where the injection rate was 100%, the specific gravity could not be adjusted to the specified value unless a highly concentrated g-acid electrolyte was injected after draining the electrolyte in the battery, which may not be possible due to the manufacturing process. It was judged.

In batteries 3, 4, 7, and 8 according to the present invention, the above-mentioned phenomena such as the formation of voids inside the filled silica granulated powder and the electrolyte being pushed up to the top of the filled silica granulated powder were not observed. There wasn't.

Next, an initial capacity test was conducted on four types of batteries 3, 4.7, and 8 according to the present invention, excluding batteries 12.5 and 6, in which the conventional drawbacks could not be overcome. At the same time, a capacity test was also conducted on Battery 9 manufactured by the conventional method. Second result
Shown in the table.

All of the batteries according to the present invention were superior to Battery 9 produced by the conventional method in both low rate discharge and high rate discharge. This is because the battery 9 manufactured by the conventional method has voids inside the filled silica granulated powder, which makes the distribution of the discharge reaction uneven.
In addition, the supply of sulfuric acid, which is an electrolytic solution, to the electrode plates is insufficient, whereas in batteries manufactured by the manufacturing method of the present invention, there are no voids inside the silica granulated powder, so the reaction distribution is uniform. This is thought to be due to the smooth supply of sulfuric acid.

Table 2 In this example, the low specific gravity sulfuric acid electrolyte had a specific gravity of 1.15 to 1.
20 was used, and the injection rate was set at 70 to 90%, but these conditions differ depending on the battery configuration and chemical formation conditions. However, if the positive and negative electrode plates of lead-acid batteries are exposed to high-density sulfuric acid electrolyte for a long time, their deterioration will be accelerated. The liquid ratio must be set so as not to cause a decrease in the formation properties of the active materials of the positive and negative electrode plates after formation.

Effects of the Invention As detailed above, the production method according to the present invention does not cause the formation of voids inside the silica granulated powder, which was seen in the conventional production method, and also significantly reduces the injection time of the sulfuric acid electrolyte. It can be shortened and has great industrial value.

Claims (1)

[Claims] 1. It is a sealed battery in which the negative electrode absorbs oxygen gas generated during battery charging, and there are 5
In a method for manufacturing a sealed lead-acid battery, in which silica powder granulated to a size of 0 to 200 microns is filled and arranged, and a sufficient amount of sulfuric acid electrolyte necessary for discharge is impregnated and retained in the granulated powder and separator. , a smaller amount of low specific gravity sulfuric acid electrolyte than can be held in the positive and negative electrode plates and the above granulated powder is injected to chemically form the electrode plate group, and then a high specific gravity sulfuric acid electrolyte is injected to form a predetermined amount of sulfuric acid electrolyte. A method for manufacturing a sealed lead-acid battery, characterized by adjusting the amount of electrolyte and the specific gravity of the electrolyte.