JPH08236100A - Sealed battery - Google Patents

Abstract

PURPOSE: To provide a sealed battery in which a gas ventilating hole of a sealing plate is not blocked up by dislocation of a welding position of a positive electrode lead terminal and which does not burst even by a sudden increase in internal pressure by arranging plural small holes in a welding part to the sealing plate of the lead terminal of a positive electrode plate. CONSTITUTION: An electrode plate group where a positive electrode plate and a negative electrode plate are opposed to each other through a separator is housed in a metallic can, and is sealed by a sealing plate also serving as an external terminal of a positive electrode having a safety valve mechanism. In this sealed battery, in a lead terminal 8 to electrically connect the positive electrode plate and the sealing plate to each other, plural holes 8a are provided in a welding part with the sealing plate, or the lead terminal itself is composed of a metallic porous plate, and porosity of its porous part is set in 40 to 60%.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a sealed battery having an improved positive electrode lead terminal.

[0002]

2. Description of the Related Art In recent years, secondary batteries such as lead storage batteries and nickel-cadmium storage batteries have been widely used as power sources for various electronic devices due to the development and popularization thereof. Recently, nickel-hydrogen storage batteries, lithium secondary batteries, etc. have been added.

Among these secondary batteries, an aqueous solution type lead storage battery, nickel cadmium storage battery, and the like, can be hermetically sealed by consuming gas generated inside the battery by a so-called Neumann method inside. On the other hand, the non-aqueous solution type lithium secondary battery is hermetically sealed by preventing overcharge / overdischarge and gas generation.

However, the battery internal pressure may suddenly rise due to an abnormality in the charger, the incorrect use of the battery, an external short circuit, or the like, and the battery may burst. Therefore, in the secondary battery,
A return type safety valve mechanism is provided in the dish-shaped sealing plate portion so that the gas generated in the battery is released to the outside when the specified internal pressure is exceeded.

A sealed battery having a conventional return-type safety valve mechanism will be described below. FIG. 4 shows a vertical sectional view of the main part of the sealed battery. In FIG. 4, 1 is a metal can which is a battery container, and 2 is a metal sealing plate fixed to the upper part of the metal can 1 by caulking via a gasket 3 which plays a role of electrical insulation and airtightness. is there. Inside the metal can 1, there is housed a power generation element 4 composed of an electrode plate group and an alkaline electrolyte, which are spirally wound with a positive electrode plate and a negative electrode plate facing each other with a separator interposed therebetween.

[0006] The sealing plate 2 is a dish plate having a gas vent hole 2a in the center thereof, and a cap-shaped positive electrode terminal 5 which is combined with the sealing plate to constitute a return type safety valve mechanism is electrically
It is mechanically connected. The positive electrode terminal 5 has a plurality of gas exhaust holes 5a formed on the periphery thereof. Further, a valve chamber 6 is formed in the center of the positive electrode terminal 5, and the elastic valve body 7 is housed in the valve chamber 6 in a compressed state. Figure 5
FIG. 6 is a plan view of the return type safety valve mechanism of FIG. 4 viewed from the bottom thereof. In FIG. 5, one end of the positive electrode lead terminal 8 is spot-welded near the center of the plate.

In the sealed battery having the return-type safety valve mechanism constructed as described above, the elastic valve body 7 is generally one utilizing the elasticity of a metal spring or rubber. This elastic valve body is disposed between the dish-shaped sealing plate and the cap-shaped positive electrode terminal as a member for closing the gas vent hole 2a provided only at the center of the sealing plate, and the battery internal pressure is set by the valve body. When it becomes larger than the above size, it deforms to open the gas vent hole 2a, releases gas to lower the internal pressure of the battery, and then returns to its original shape so that it can be used again. On the other hand, the method of connecting the lead terminals to the positive and negative terminals at the time of manufacturing the battery is to prevent the lead terminals 8 of the positive electrode plate, which is generally a solid plate without holes, from blocking the gas vent holes 2a outside the bottom of the dish-shaped sealing plate. The negative electrode plate is attached by spot welding, and a terminal is spot-welded to the inner bottom portion of the metal can 1 or the outer peripheral portion of the negative electrode plate is brought into direct contact with the inner surface of the metal can 1.

[0008]

However, in the above-mentioned conventional structure, in the case of the battery having the cylindrical structure, when the positive electrode lead terminal is welded to the bottom portion of the dish-shaped sealing plate, the sealing plate is caused by the variation of the welding position of the positive electrode lead terminal. In some cases, the gas vent hole provided in the bottom is blocked by the positive electrode lead terminal, the discharge of gas is hindered, and the internal pressure of the battery rises rapidly, leading to rupture.

In order to solve such a problem, Japanese Utility Model Laid-Open No. 56-12
Japanese Patent No. 3464 discloses a positive electrode lead terminal having a structure in which one hole is provided in a welded portion of the positive electrode lead terminal. However, in such a structure, the positions of the lead terminal holes and the gas vent holes must be accurately aligned in order to facilitate the gas discharge, and if the spot positions of the lead terminals still deviate. The above problems are not solved.

The present invention solves the above-mentioned problems of the prior art, in which the gas vent hole is not blocked regardless of the displacement of the welding position of the positive electrode lead terminal, and the return type safety valve mechanism having a high safety structure. An object of the present invention is to provide a sealed battery having

[0011]

[Means for Solving the Problem] A positive electrode plate and a negative electrode plate are opposed to each other with a separator interposed between them, and the electrode plates are housed in a metal can, and the metal can is sealed with a sealing plate having a safety valve mechanism and serving as a positive electrode external terminal. In the sealed battery, the lead terminal for electrically connecting the positive electrode plate and the sealing plate has a plurality of holes in the welded portion with the sealing plate, or the lead terminal itself has a multi-hole metal plate. And the open degree of the perforated portion is 40 to 60%.

[0012]

With this configuration, when the positive electrode lead terminal is welded to the bottom of the dish-shaped sealing plate, the gas vent hole provided in the bottom of the dish-shaped sealing plate is apparently seen by the positive electrode lead terminal due to the variation in the welding position of the positive electrode lead terminal. Even if the battery is blocked, the hole in the welded part of the lead terminal ensures a path for the gas in the battery to be exhausted to the outside through the gas vent hole. It is possible to prevent the battery from bursting even when the internal pressure of the battery rises sharply due to an emergency situation such as a battery misuse or an external short circuit.

[0013]

【Example】

(Embodiment 1) An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows a positive electrode plate with lead terminals in which a lead terminal 8 having a plurality of small holes 8a at one end, which is a welded portion with a sealing plate, is spot-welded to a positive electrode plate having a plain portion 9 on one edge. FIG.

The following experiment was conducted using this positive electrode plate.
First, the open area ratio of the perforated portion, which is the welded portion of the lead terminal 8 with the sealing plate, is 0, 10, 20, 30, 40, 5 respectively.
A 0 to 60% lead terminal of each level and a known positive electrode plate (length 63 mm × width 40 mm × thickness 0.63 mm) were spot-welded to prepare a positive electrode plate with a lead terminal as shown in FIG.

When the open area ratio of the perforated portion exceeds 60%, the lead terminals are easily broken in the process of manufacturing the battery, and the internal resistance of the battery is remarkably increased due to the decrease in conductivity. The open rate of the lead terminals was set to 60% or less.

These positive electrode plates with lead terminals and known cadmium negative electrode plates (length 80 mm x width 40 mm x thickness 0.
57 mm) AA with a nominal capacity of 600 mAh
A size nickel-cadmium battery was obtained.

At this time, as shown in FIG. 2, the gas vent hole 2a constituting the return type safety valve mechanism was spot welded so as to be closed at one end of the lead terminal 8 provided with the small hole. The results of the battery rupture test when 100 cells of each of these batteries were charged at a current of 6 A (10 CA) are shown in (Table 1).

[0019]

[Table 1]

Next, of the above batteries, the relationship between the internal pressure and the gas exhaust flow rate was measured for the lead terminal opening ratios of 0%, 40%, and 60%. The result is shown in FIG.

As is clear from (Table 1), it was confirmed that the sealed battery having the positive electrode lead terminal according to this example is superior in safety. Further, from FIG. 3, when the gas vent is completely closed, the gas exhaust flow rate is less than half of that of the conventional positive electrode lead plate spot-welded sealing plate. , The risk of battery explosion under abnormal conditions is clear.

As the lead terminal other than the above-mentioned embodiment, a metal porous plate such as a pocket perforated steel plate may be used as the lead terminal material.

[0023]

As described above, according to the present invention, a metal can forming a battery container accommodating a power generating element, a plate-like sealing plate having a gas vent hole for sealing the metal can, and a metal can arranged on the sealing plate are provided. A safety valve mechanism composed of a cap-shaped positive electrode terminal in which an elastic valve body for closing the gas vent is located in the valve chamber, and a positive electrode lead terminal for electrically connecting the positive electrode plate in the power generation element and the cap-shaped positive electrode terminal. In the sealed battery described above, the positive electrode lead terminal is provided with a plurality of holes in a welded portion with the cap-shaped positive electrode terminal, so that the position condition of spot welding of the positive electrode lead terminal to the dish-shaped sealing plate is irrelevant. In addition, the gas vents are not all blocked, the gas exhaust path can be secured, and the battery can be prevented from bursting due to a sudden increase in gas pressure in an abnormal state.

[Brief description of drawings]

FIG. 1 is a front view of a positive electrode plate with a lead according to an embodiment of the present invention.

FIG. 2 is a plan view of a reset type safety valve mechanism in which one end of a lead terminal is spotted so as to block a gas vent hole of a sealing plate, viewed from the bottom.

FIG. 3 is a diagram showing the relationship between the open area ratio of the perforated portion of the lead terminal, the battery internal pressure, and the gas exhaust flow rate from the gas vent hole.

FIG. 4 is a vertical cross-sectional view of the main part of the sealed battery.

FIG. 5 is a plan view of a return type safety valve mechanism in which a conventional positive electrode lead terminal and a dish-shaped sealing plate are spot-welded at regular positions as seen from the bottom.

[Explanation of symbols]

 1 Metal Can 2 Sealing Plate 2a Gas Vent 3 Gasket 4 Power Generation Element 5 Cap Positive Electrode Terminal 5a Gas Exhaust Hole 6 Valve Chamber 7 Elastic Valve Body 8 Positive Electrode Lead Terminal 8a Hole 9 Solid Part of Positive Plate

Claims (3)

[Claims] 1. A hermetically sealed battery in which a metal can having a positive electrode plate and a negative electrode plate facing each other with a separator interposed between them is sealed with a sealing plate having a safety valve mechanism and also serving as an external terminal of one electrode. The sealed battery, wherein the lead terminal for electrically connecting the positive electrode plate and the sealing plate has a plurality of holes in a welded portion with the sealing plate. 2. The sealed battery according to claim 1, wherein the lead terminal is made of a metal porous plate having a large number of holes. 3. The open degree of the perforated portion of the lead terminal is 40 to 6.
It is 0%, The sealed battery of Claim 1 or 2.