JPS5998452A - Alkaline battery - Google Patents

Abstract

PURPOSE:To release gas generated inside a battery when gas pressure is increased above a specified level outside the battery but usually keep good leakage resistance by forming an adhesive film in a gas exhausting part of the inner surface of a sealing plate in which a current collector is welded, and in an inserting part of the current collector to a gasket. CONSTITUTION:An adhesive film 9 is formed in the area along a gas exhausting hole 8a of the inner surface of a sealing plate 8, the welding part of a current collector 6, and the inserting part of the current collector 6 to a gasket 5. Electrolyte creepage along the current collector is suppressed by the adhesive film 9 formed in the inserting part of the current collector 6 to the gasket 5. Since the gas exhausting hole 8a is covered with the adhesive film 9, leakage from the hole is prevented. When the pressure of gas generated inside a battery is abnormally increased, the adhesive film covering the gas exhausting hole 8a is broken, the gas is released outside through the gas exhausting hole 8a.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an alkaline battery having a function of discharging internally generated gas and having improved leakage resistance.

It is known that alkaline batteries generate a small amount of gas during discharge or storage.

In this case, if gas is generated to a normal level, there will be no problem for the battery itself or the equipment using the battery; In the worst case, if abnormal gas is generated due to charging, etc., the battery may explode.

For this reason, some batteries of this type use an insulating gasket having a detonation prevention valve, and further have through holes provided in the cathode sealing plate to facilitate gas discharge to the outside of the battery.

However, if you do this, the following problem will occur. In other words, in alkaline batteries, the electrolyte reaches the current collector rod due to the electrocapillary action that occurs between the negative potential of the electrode and the surface tension at the electrolyte interface, and the electrochemical reaction in which oxygen gas in the air is reduced to OH-. There is a phenomenon of creeping along. Therefore, there was a risk that this electrolytic solution would move along the inner surface of the sealing plate and eventually leak out from the gas exhaust hole.

Therefore, conventionally, a breathable alkali-resistant synthetic resin film such as polyethylene or polypropylene is adhered to the entire inner surface of a sealing plate with gas discharge holes using an alkali-resistant adhesive to prevent sudden gas generation (thus tearing the film). There is a device that allows gas to be discharged. In other words, according to this device, by covering the gas discharge hole of the sealing plate with a synthetic resin film, abnormal gas generation can be reliably discharged to the outside, and it also allows the gas to crawl along the current collector rod. It can be expected to effectively prevent the rising electrolyte from leaking outside.

However, although it is preferable to attach a synthetic resin film to the entire inner surface of the sealing plate in order to prevent the electrolyte from creeping up, in this type of alkaline battery, the collector rod is welded to the inner surface of the sealing plate. Since this is common, this current collector rod gets in the way when applying the film, making it difficult to apply it well, and therefore, a sufficient effect in terms of leakage resistance may not be obtained.

This invention has been made to eliminate the above-mentioned drawbacks, and has an adhesive on at least the gas exhaust hole portion and the fitting portion of the current collector rod to the gasket on the inner surface of the sealing plate, which has a gas exhaust hole and to which the current collector rod is welded. It is an object of the present invention to provide an alkaline battery which can promptly release internally generated gas having a pressure higher than a predetermined pressure to the outside by forming a coating layer, and which can always obtain good leakage resistance.

An embodiment of the present invention will be described below with reference to the drawings.

In the figure, 1 is a cylindrical anode metal can, and this metal can 1 is made by drawing a nickel-plated steel plate.

The metal can 1 is filled with power generating elements. That is, in this case, a gelled zinc cathode material 2 is filled in the center of the metal can 1, and a synthetic fiber separator 4 is placed around the cathode material 2.
An anode mixture 3 mainly composed of manganese dioxide is filled through the tube.

An insulating gasket 5 is provided at the opening of the metal can 1.

This gasket 5 is made of nylon 6.6. The inner cylindrical part 51 is integrally molded from synthetic resin such as polypropylene.
An outer cylindrical part 52 is provided around the inner cylindrical part 51 via a connecting part 53 of approximately 0.8 to 16 gmm, and a stepped part 54 is provided at the upper part of the inner cylindrical part 51 and the outer cylindrical part 52. A folding projecting wall 5 is provided along the periphery of the cylindrical portion 52.
5. Furthermore, the connecting portion 53 of the gasket 5 has a wall thickness of 0.1 to 3 m, which is such that it will burst when the internal pressure of the battery rises abnormally to a pressure of about 30 to 60 kg/cm2.
It has a thin part 56 of about m.

A cathode sealing plate 8 is placed on the stepped portion 54 of the gasket 5 via an annular metal support 7 having a ventilation hole 7a. This sealing plate 8 has a gas discharge hole 8a.

Further, a current collector rod 6 which is drawn out from the cathode agent 2 and fitted into the hollow part of the inner cylindrical part 51 of the gasket 5 is fixed to the inner surface by welding or the like.

In this case, an adhesive coating layer 9 is formed from the gas discharge hole 8a portion on the inner surface of the sealing plate 8 to the welded portion of the current collector rod 6 and the fitting portion of the current collector rod 6 to the gasket 5. This coating layer 9 is made of a rubber adhesive or a synthetic resin, such as polyisobutylene.

Aliphatic polyamide resin, chlorosulfonated polyethylene, haloprene rubber, chlorinated polyethylene.

Adhesives such as ethylene-ethyl acrylate copolymer, vulcanized or unvulcanized natural rubber, SBJ neobrene, butyl rubber, nitri rubber, polybutadiene rubber, and fluorinated rubber are used.

Here, the gas discharge hole 8a of the sealing plate 8 has a diameter of 0.4 to Q.
It has been confirmed that if the adhesive is about gmm, not only can gas be discharged, but also that it does not flow out from the discharge hole 8a during application due to the viscosity of the adhesive. Further, the adhesive is applied by dropping with a syringe or by brushing, and then dried under pressure or reduced pressure to form the adhesive film 9. The increase in the thickness of the coating 9 at this time causes sufficient rupture.

In this state, when the opening of the metal can 1 is tightened in the radial direction, the opening is bent inward and the folding projecting wall 5 of the gasket 5 is bent.
The opening is sealed by pressing the sealing plate 8 through the opening 5. In Figure 1, 10 is an insulating tube and 11 is a metal jacket.

According to such a configuration, the electrolyte that constantly tries to creep up along the current collecting rod 6 is prevented by the adhesive coating layer 9 formed on the fitting portion of the current collecting rod 6 to the gasket 5. Speed is drastically reduced.

Moreover, since the gas discharge hole 8a is also covered with the adhesive coating layer 9, it is possible to reliably prevent leakage to the outside in a short period of time. If the gas pressure inside the battery rises abnormally in this state, first the thin wall portion 56 of the gasket 5 is pressed, expands and breaks, and the gas passes through the ventilation hole 7a of the metal support 7 and reaches the inside of the sealing plate 8. Then, the adhesive coating layer 9 covering the gas exhaust hole 8a is pressed and ruptured, whereby the gas is discharged to the outside through the exhaust hole 8a. In other words, by rubbing E like this, you can suppress the movement of the electrolyte that tends to creep up along the current collector rod 6 and obtain good leakage resistance.Moreover, if the gas pressure inside the battery rises abnormally, it can be quickly removed. It can also be released to the outside. Further, since the adhesive is simply applied with the current collecting rod 6 welded to the sealing plate 8, a good adhesive coating layer 9 can be obtained, which is also advantageous in terms of leakage resistance.

By the way, L-type 6-type Alkai pond [A] to which this invention was applied
100 batteries were each made (Battery CB, which has a gas exhaust hole on the cathode sealing plate but has no adhesive coating layer), and battery [C], which has no gas exhaust hole on the cathode sealing plate.60
When the internal pressure was increased by forced charging for 1 hour at 0 mA current and a burst test was performed, the results shown in Table 1 were obtained.

Here, in each of the batteries [A], (B), and (C), the insulating gasket described in the above embodiment is used.

In addition, in this case, the number of ruptured batteries is counted as damage to the external appearance of the battery, such as a torn insulating tube, a protruding current collector rod, or a torn caulked part of the metal jacket.The thin part of the gasket is damaged by gas pressure. A torn battery does not cause any damage to its appearance, so it is not counted as a battery explosion.

Table 1 Next, 100 of each of these batteries [A], [B], and [C] were placed in a constant temperature and humidity chamber with a temperature of 60 degrees Celsius and a humidity of 90 degrees RH.
After storage for 0 days, leakage was investigated by color reaction on the outer surface of the sealing plate using phenol red as an alkaline indicator, and the results shown in the table below were obtained.

Table 2 However, from the results in Tables 1 and 2, the battery [A] obtained by the present invention is more likely to explode due to the generation of abnormal gas during battery use than the conventional batteries (B) and (C). It has been found that not only is it durable, but it also has an excellent constant leakage resistance effect.

It should be noted that the present invention is not limited to the above-mentioned embodiments, but can be implemented with appropriate modifications without changing the gist.

For example, in the above description, the adhesive coating layer 9 is formed from the gas exhaust hole 8a portion on the inner surface of the sealing plate 8 to the welded portion of the current collector rod 6 and the fitting portion of the current collector rod 6 to the gasket 5. Effects similar to those described above can also be obtained by forming an adhesive coating layer 9 on the hole 8a portion and the fitting portion of the current collector rod 6 into the gasket 5.

[Brief explanation of drawings]

The drawing is a schematic diagram showing an embodiment of the present invention. 1... Metal can 2... Cathode material 3... Anode mixture 4... Separator 5...-Gasket
51... Inner cylindrical part 52... Outer cylindrical part 53
... Connecting portion 54 ... Step portion 55 ... Projection wall 56 ... Thin wall portion 6 ... Current collector rod 7 ... Metal support 7a ... Ventilation hole 8 ... Sealing plate
8a... Gas discharge hole 9... Adhesive coating layer 10...
・Insulating tube 1)...Metal jacket

Claims (2)

[Claims] (1) A cylindrical metal can filled with a power generation element, an insulating gasket provided at the opening of the metal can and having a thin wall portion that ruptures due to gas pressure, and placed on the gasket via a metal support. a current collector rod led out from the power generation element, fitted into the gasket, and fixed to the sealing plate; and at least a gas discharge hole portion of the sealing plate and the collector rod. An alkaline battery characterized by comprising an adhesive coating layer applied and formed on a portion of an electric rod that fits into a gasket. (2) Claim 1, characterized in that the adhesive coating layer is also formed on the current collector rod fixing portion ζ of the sealing plate.
Alkaline batteries as described in section.