JPS59207558A - Manufacture of closed lead-acid battery - Google Patents

Abstract

PURPOSE:To manufacture a closed lead-acid battery having low material cost and low manufacturing cost by forming a container with heat-welding synthetic resin films with an electrode group interposed except for one nonwelded portion and using the nonwelded part as a safety valve. CONSTITUTION:An electorde group 6 comprising a positive plate, a negative plate, and a separator is placed between two film-shaped synthetic resins 8 which have acid resistant and heat welding property. The bottom and left and right sides of the resin of the electrode group 6 are heated with a heat press, and the resin is welded to form a container. A specified dilute sulfuric acid electrolyte is poured from the upper part which is not welded. Then this nonwelded part is welded with the heat press except for one part, and electrode poles 7 are sealed at the same time. The nonwelded part forms a safety valve 4 by facing the resin in parallel without gaps.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method for manufacturing a sealed lead-acid battery, and in particular to an improved safety valve thereof.

Conventional configuration and problems Sealed lead-acid batteries have a separator called a glass mantle that holds the electrolyte and does not flow, so the electrolyte does not overflow to the outside and is widely used as a convenient and portable power source. ing.

Sealed lead-acid batteries have a structure in which oxygen gas generated at the positive electrode plate during charging is absorbed by the negative electrode plate, so that gas usually does not escape to the outside of the battery.

However, when charging with a large current, the oxygen gas generated at the positive electrode plate is greater than the oxygen gas absorption capacity of the negative electrode plate, and hydrogen gas is also generated from the negative electrode plate, so if the battery is completely sealed, becomes quite high pressure. Therefore, a safety valve is provided that opens when the internal pressure of the battery increases.

Generally, this type of safety valve has a structure in which a rubber valve 1 is placed over a valve cylinder 2 as shown in FIG. However, with such a rubber valve structure, it is difficult to mechanically fit the rubber valve 1 into the valve barrel 2, and the actual situation is that the rubber valve 1 is manually fitted after injecting the electrolyte into the electrolyte 3. Not only does this type of safety valve increase manufacturing costs because it requires assembly man-hours, but the material cost of the rubber valve itself is higher than the synthetic resin used in electrical appliances, making the raw material cost relatively high. Put it away.

Furthermore, the process of inserting the electrode plate group into the electric cell is difficult to mechanize, which poses a problem in mass production.

Purpose of the Invention The present invention solves the above-mentioned problems of the conventional technology, and is suitable for mass production that can be easily mechanized by using a film or sheet-like electric shield and integrally molding the safety valve so that it is electric. The purpose of this new structure is to reduce manufacturing costs and reduce material costs at the same time.

Structure of the Invention The present invention provides an electrode group consisting of a positive electrode plate, a negative electrode plate, and a separator, in the form of two acid-resistant and heat-weldable films.
Alternatively, the synthetic resin bodies surrounding the electrode plate group are heat welded and electrified, leaving one unmelted part, and the internal pressure of the battery is higher than the outside air pressure in the unwelded part. When the pressure is high (when the pressure is high), the valve opens and gas is released from the gap, and when the pressure is low (when the pressure is reduced), the valve closes and the gap is sealed. It is characterized by a safety valve whose bodies are aligned parallel to each other with almost no gaps.

The valve opens when the battery is pressurized for safety reasons, and the valve closes when the battery is depressurized to prevent self-discharge from progressing when the negative electrode plate reacts with oxygen in the atmosphere when the battery is stored in a charged state. This is to prevent this. After a while after charging is completed, the oxygen generated from the positive electrode plate and remaining inside the battery is absorbed by the negative electrode plate, and the inside of the battery becomes depressurized. When the pressure is reduced, the safety valve contracts, and the gap is completely closed, resulting in a sealed state, and the inside of the battery is cut off from the outside air.

DESCRIPTION OF EMBODIMENTS The present invention will be described in detail below. In Figure 2, positive electrode plate 1
Sheet (length 60 x width 70m +++ x thickness 3.0rrvn),
2 negative electrode plates (length: 50 meters x width: 70,711 meters x thickness: 1.3 meters)
) and a glass mantle separator are sandwiched between two films or sheets of polyethylene 8 having a thickness of 0.3 and are acid-resistant and heat-weldable. Heat only the bottom and left and right sides of the surrounding area from the outside at 150°C for about 1 minute using a heat press,
The polyethylene is welded 5 to each other in an attempt to generate electricity, and a predetermined dilute sulfuric acid electrolyte is injected from the unwelded upper part. After pouring the liquid, heat press the upper part again under the same conditions to seal the pole pillar 7, and at the same time seal the unwelded part where the two films or sheets of polyethylene 8 face each other in parallel with almost no gap at one place with a safety valve. Formed as 4. This unwelded part opens when the internal pressure of the battery is higher than the outside air pressure (when pressurized) and releases the gas generated from the electrode plate group through the gap, and conversely closes when it is low (when pressure is reduced). It acts as a valve to seal the gap.

In this structure, the conditions for further improving the function of the safety valve, especially the airtightness during depressurization, are as follows.

The material of the synthetic resin is AS (acrylonitrile/styrene copolymer) or ABS (acrylonitrile/styrene copolymer).
It has been found that polyethylene and polypropylene, which are softer than butadiene/styrene copolymer (butadiene/styrene copolymer) resin, are easier to discharge internal gases and have better airtightness./ζ0This is also related to the thickness of the resin. The same can be said for thinner materials.

Next, the safety valve, that is, the synthetic resin parts that face each other in parallel, is narrower when not welded, and the longer the distance, the better the airtightness.

However, when the battery is in a pressurized state, making the width extremely narrow may cause too much internal pressure and damage the battery, so it is better to lengthen the distance with an appropriate width. Creating a maze structure to increase the distance improves airtightness. In other words,
As shown in FIGS. 2 and 3 a and b, by providing a thermally welded portion 5a that blocks part of the gas path in the unwelded portion, the substantial gas discharge distance can be reduced. It can be made longer. This type of thermal welding can be easily performed at one time by processing a hot press jig to a predetermined size.

Additionally, by applying a liquid such as silicone oil to the inner wall of the safety valve 4 as shown in Figure 3a, the surface tension of the liquid will cause the safety valve 4 to close tightly when the pressure is reduced, preventing air from entering the battery. Alternatively, as shown in Fig. 3, a liquid 9 such as silicone oil is applied to the inner wall of the safety valve 4, and a clip 10 (thickness 1.0 mm) made of an elastic material is attached to the outside of the safety valve. Reliability will be further improved if an external force is applied by clamping the battery, so that the valve does not open unless the pressure inside the battery increases.

Next, the self-discharge characteristics of the battery with the above configuration were investigated.

Figure 4 shows the storage period and remaining capacity (initial performance is 100%
FIG. A is a conventional example, B is an embodiment of the present invention (shown in FIG. 2), and B is slightly inferior to A in self-discharge characteristics.

In addition, a battery C (the one in FIG. 3a) of the second embodiment of the present invention, which has the same structure as B but has a liquid 9 such as Noricon oil applied to the inner wall of the safety valve, and a battery C (the one in FIG. 3a) that has a liquid 9 such as silicone oil applied to the safety valve. 4 and apply ABS to the safety valve part from the outside.
It was possible to obtain approximately the same properties using materials with elasticity such as .

Effects of the Invention As described above, according to the present invention, the following effects can be obtained.

(1) The safety valve has a structure in which heat-welded notebook-like or film-like synthetic resin bodies are not welded, so it is not only extremely easy to mechanize, but also can be formed in a short time, compared to conventional products. It requires less man-hours, has high productivity, and can reduce battery manufacturing costs.

(2) Because the structure is such that the safety valve is integrally molded to cover the electrode group with a sheet-like or film-like synthetic resin material, it is difficult to apply electricity to the electrode group with conventionally structured batteries. It is also easy to mechanize the insertion, reducing the number of man-hours.

(3) In terms of materials, the material cost can be reduced because it can be constructed from a thin sheet-like or film-like synthetic resin body including the electrical insulation valve and the safety valve.

[Brief explanation of the drawing]

Figure 1 is a perspective view of a conventional sealed lead-acid battery, Figure 2 is a perspective view of a sealed lead-acid battery according to an embodiment of the present invention, and Figure 3a.
, b are enlarged views of main parts showing other embodiments, and FIG. 4 is a diagram showing self-discharge characteristics. 4...Safety valve, 6...Welded part, 6...
... Plate group, 8 ... Film-like or sort-like polyethylene. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Fig. 12' 7 Fig. 3 (of) (b)

Claims (1)

[Claims] (1) An electrode plate group consisting of a positive electrode plate, a negative electrode plate, and a seven-layer plate is sandwiched between two film-like or sheet-like synthetic resin bodies that are acid-resistant and heat-weldable, The synthetic resin body around the electrode plate group is thermally welded to generate electricity, leaving one unwelded part, and the unwelded part is opened to release gas when the internal pressure of the battery is higher than the outside air pressure. A closed type lead, characterized in that the two film-like or sheet-like synthetic resin bodies are arranged parallel to each other with almost no gap to form a safety valve so that the valve releases the air and, conversely, closes when the temperature is low to seal the gap. Method of manufacturing storage batteries. (2) The method for manufacturing a sealed lead-acid battery according to claim 1, wherein the parallel unwelded portions of the synthetic resin body have a labyrinth structure. A method for manufacturing a sealed lead-acid battery according to paragraph 2. (4) Any of claims 1 to 3, in which the parallel unwelded portions of the synthetic resin body are held between the outside of the electric housing by an elastic U-shaped 2.8-g. A method for producing a sealed lead-acid battery as described in .