JPH07201309A - Sealing structure of explosion preventive battery - Google Patents

Abstract

PURPOSE:To provide a sealing structure of an explosion preventive battery wherein with the sealing structure, ignition and explosion in the battery are surely prevented and assembly workability is improved and the process management is simplified. CONSTITUTION:A projected part 4b extruded downward is formed at the center part of a sealing plate 4, a conductive metal plate 6 having a gas emitting out hole 6b is put between the sealing plate 4 and a lead 7, a cylindrical part 6a standing upward is formed in the center part of the metal plate 6, and the cylindrical part 6a is fitted with the projected part 4b of the sealing plate 4. At the same time, the lower face of the metal plate 6 is welded with the lead 7 to communicate the lead 7 and a terminal plate 3 electrically and at the time when the gas pressure in a case 1 increases to a prescribed level or higher, being pushed by the gas pressure, the sealing plate 4 is forced and moves upward, so that the projected part 4b of the sealing plate 4 is parted from the cylindrical part 6a of the metal plate 6.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an explosion-proof battery sealing structure.

[0002]

2. Description of the Related Art Conventionally, as a sealing structure for explosion-proof batteries,
For example, as disclosed in JP-A-2-288063, the temperature rise inside the battery is suppressed within the initial stage to prevent ignition of the battery, and when the pressure inside the battery rises, gas is vented to explode the battery. It is known to prevent this. As shown in the partially broken vertical sectional view of FIG. 8, this sealing structure has a cylindrical battery case 31, a power generating element 36 housed in the battery case 31, and an open end 31 a of the battery case 31. A terminal plate 35 fixed through a sealing gasket 32 and formed with a gas vent hole 30, and one end side attached to the power generation element 36 and the other end side electrically connected to the terminal plate 35 through an explosion-proof mechanism. And a lead 38.

The explosion-proof mechanism includes a metallic sealing plate 33 disposed below the terminal plate 35, a lead stripper 34 disposed below the sealing plate 33, and the sealing plate 33 and the lead stripper 34. It is mainly composed of an intermediate fitting body 40 fitted in between.

The sealing plate 33 has a disk shape and has a protrusion 33a protruding downward at the center thereof, and a thin portion 33b radially extending from the vicinity of the base of the protrusion 33a is formed on the upper surface. The terminal plate 35 is caulked and fixed to the upper end portion 31a of the battery case 31 via the gasket 32.

The lead stripper 34 is made of an insulating material and has a disk shape, and the sealing plate 3 is provided at the center thereof.
An insertion hole 34a through which the protrusion 33a of No. 3 is inserted is formed. The intermediate fitting body 40 is made of an insulating material and has a disc shape. The intermediate fitting body 40 is recessed and fitted between the stripper 34 and the sealing plate 33 and integrally coupled.

The lead 38 attached to the power generating element 36 at one end is connected to the lead stripper 3 at the other end.
4 and the lower surface of the protruding portion 33a facing downward from the insertion hole 34a are connected by ultrasonic welding and extend beyond the lower surface of the protruding portion 33a. Also, this welding is performed several times to ensure proper welding strength.

In the battery having the explosion-proof mechanism as described above, when the internal pressure of the battery rises due to gas generation / filling due to chemical change inside the battery due to progress of overcharge or short circuit, the sealing plate 33 becomes the terminal plate. The lead 38 is pressed toward 35 and moves upward, and the lead 38 welded to the lower surface of the protrusion 33 is separated from the sealing plate 33 at the welded portion, or the lead 38 itself is broken to interrupt the current.

When a large amount of gas is generated inside the battery, the thin portion 33b of the sealing plate 33 is cleaved, the gas is guided toward the terminal plate 35, and further, into the atmosphere through the gas vent hole 30. The exhaust gas prevents the battery from exploding.

[0009]

However, in the sealing structure provided with the above-mentioned explosion-proof mechanism, the lead 3 is arranged so that the current is cut off when the internal pressure of the battery reaches a predetermined internal pressure.
It is necessary to properly set the welding strength between No. 8 and the protrusion 33a.

That is, if the welding strength is too high, the thin portion 33b of the sealing plate 33 is torn before the lead 38 is peeled or broken when the internal pressure rises, the internal pressure is released and the explosion is prevented. However, since the current continues to flow, the temperature rises and there is a risk of ignition. Therefore, this welding strength must be set to an internal pressure lower than the internal pressure (for example, 10 to 30 kg / cm ² at a temperature of 20 ° C.) at which the thin portion 33b is split. On the other hand, if the welding strength is too low,
There is a possibility that an error may occur due to a slight increase in the internal pressure during use or storage within a normal range such as charging / discharging or high temperature storage of the battery, and the lead 38 may be peeled or broken unnecessarily and may not function as a battery. . Therefore, during use and storage within the normal range, the welding strength must be set high so that the lead 38 is not peeled or broken.

Therefore, the range of welding strength must be set extremely strictly, and high welding accuracy is required in the welding process, so that there is a problem that assembly work and process control are inevitably complicated. .

Further, in order to ensure proper welding accuracy,
Since this welding is performed several times, welding defects such as wear and deformation of the welded portion are likely to occur due to heating and cooling at the time of welding, and it is highly accurate to prevent the occurrence of these welding defects. There is also a problem that welding management becomes necessary and assembly work and process management become more complicated.

Furthermore, the lead 38 has an insertion hole 34a.
Is positioned so as to be connected to the lower surface of the protruding portion 33a facing downward from the lower surface of the lead stripper 34 and the protruding portion 33a.
Since it is necessary to perform welding on the lower surface of a, a high positioning accuracy is required at the time of this welding, and there is a problem that assembly work and process control become more complicated. The present invention solves the above problems, and an object thereof is to provide an explosion-proof battery sealing structure capable of improving the assembly workability and simplifying the process control and surely preventing the ignition and explosion of the battery. It is in.

[0014]

To achieve the above object, the present invention is directed to a power generating element housed in a battery case, leads extending from the power generating element, and a sealing member at an open end of the battery case. A metal terminal plate that is attached through a gasket and has a gas vent hole, and is electrically connected to the terminal plate and disposed below it, and is attached to the open end of the battery case through a sealing gasket. And a lower surface of the sealing plate electrically connected to the lead, and when the gas pressure in the case rises above a predetermined level, the sealing plate is urged upward by receiving the gas pressure. In a sealing structure for an explosion-proof battery, which is insulated from the leads and formed so as to be broken when the gas pressure is further increased, a protrusion protruding downward is formed at the center of the sealing plate, and The above A conductive metal plate having a gas vent hole opened between it and a cylindrical part that stands upright at the center of the metal plate, and the cylindrical part is formed on the sealing plate. When the protrusion is fitted and the lower surface of the metal plate is welded to the lead to electrically connect the lead and the terminal plate, and when the gas pressure in the case rises above a predetermined level, the sealing plate will It is formed such that it receives a gas pressure and is urged upward so that the protruding portion of the sealing plate is separated from the cylindrical portion of the metal plate.

Here, it is desirable that the peripheral portion of the sealing plate is formed in a Z-shaped cross section.

To achieve the above object, the present invention provides a power generating element housed in a battery case, leads extending from the power generating element, and a sealing gasket at the open end of the battery case. A metal terminal plate that is attached and has a gas vent hole, and a metal terminal plate that is electrically connected to the terminal plate and that is disposed below the terminal plate and that is attached to the open end of the battery case through a sealing gasket. A lower surface of the sealing plate is electrically connected to the leads, and when the gas pressure in the case rises above a predetermined level, the sealing plate is urged upward to be insulated from the leads. In the sealing structure of the explosion-proof battery, which is formed so as to be broken when the gas pressure is further increased, a protrusion projecting downward is formed at the center of the sealing plate, and the sealing plate and the lead are A conductive metal plate having a gas vent hole is inserted in the metal plate, and the peripheral edge of the metal plate is caulked together with the sealing plate and the terminal plate into the opening of the case through the gasket, and the central part of the sealing plate. By elastically deforming downward, the projection of the sealing plate is pressed against the upper surface of the metal plate and the lower surface of the metal plate is welded to the lead to electrically connect the lead and the terminal plate, When the gas pressure in the case rises above a predetermined level, the sealing plate is formed so as to receive the gas pressure and be urged upward to separate the protrusion of the sealing plate from the metal plate. is there.

[0017]

According to the present invention having the above-described structure, the sealing plate and the lead are not directly connected to each other by welding, and the protrusion and the lower surface of the sealing plate of the metal plate are welded with the lead. Since the connection is made by fitting with the tubular portion or by pressing the protruding portion of the sealing plate against the upper surface of the metal plate, it is possible to perform welding management such as highly accurate welding accuracy setting like connection by welding. It becomes unnecessary.

Further, since the lead can be welded to a substantially arbitrary position on the lower surface of the metal plate instead of the predetermined position of the sealing plate, the welding work is simplified.

Further, the fitting strength between the protrusion and the tubular portion is set by adjusting the shapes and materials of the protrusion of the sealing plate and the tubular portion of the metal plate in advance. it can. Therefore, compared with the case where the electrical connection and insulation between the lead and the sealing plate are caused by welding and welding breakage, a current interruption characteristic such that the current is appropriately interrupted when the inside of the battery reaches a predetermined internal pressure. The setting becomes easy, and the variation in the current cutoff characteristic becomes small.

Furthermore, the peripheral portion of the sealing plate has a cross section Z.
In the case of the letter shape, the sealing plate can bend upward under the increased gas pressure without being restricted by the peripheral edge portion crimped at the open end of the battery case. Therefore, since the deflection can be easily set, the current cutoff characteristic can be easily set, and the variation in the current cutoff characteristic can be reduced.

Further, even if the central portion of the sealing plate moves upward due to the increased gas pressure, the peripheral edge portion of the sealing plate is not dragged upward, so that the gasket and the peripheral portion of the sealing plate are separated from each other. Airtightness is not impaired. Therefore, the airtightness of the battery is not impaired.

When the peripheral portion of the metal plate is formed so as to be caulked to the open end of the battery case together with the sealing plate and the terminal plate through the sealing gasket, the metal plate is the metal case. Since the external force is applied to the sealing portion of the battery, the strength of the battery sealing structure is improved.

Further, when the gas pressure in the battery case rises above a predetermined level, the sealing plate receives the gas pressure and is urged upward, so that the protrusion of the sealing plate becomes the cylindrical portion of the metal plate. Or separated from the upper surface of the metal plate. Therefore, when gas is generated due to overcharge or a short circuit and the gas pressure rises, the current is cut off and the temperature rise and ignition of the battery are prevented. Then, even if the gas generation is not stopped and the gas pressure is further increased after the electric current is cut off as described above, the sealing plate is broken and the explosion is prevented.

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 is a partially broken vertical sectional view showing a first embodiment of the explosion-proof battery sealing structure according to the present invention. In FIG. 1, the sealing structure of the present embodiment is a cylindrical battery case 1
A power generating element 8 housed in the battery case 1, and a plurality of gas vent holes 3a fixed to the open end of the battery case 1 via a polypropylene sealing gasket 2.
And a lead 7 whose one end side is attached to the power generating element 8 and whose other end side is electrically connected to the terminal plate 3 via an explosion-proof mechanism.

The explosion-proof mechanism includes a metallic sealing plate 4 disposed below the terminal plate 3, a metal plate 6 disposed below the sealing plate 4, the metal plate 6 and the sealing plate 4. The insulating ring 5 is laminated between the peripheral portions of the insulating ring 5.

The lead 7 is made of aluminum, one end side of which is attached to the power generating element 8 and the other end side thereof is connected to an arbitrary position on the lower surface of the metal plate 6 by welding. The metal plate 6 is an aluminum disc, and has gas vent holes 6b formed at a plurality of positions, and a cylindrical portion 6a standing upward in the central portion. And the metal plate 6
Insulating ring 5 made of polypropylene on the upper surface of the periphery of
Are laminated to electrically insulate the peripheral edge of the sealing plate 4 and the peripheral edge of the metal plate.

The peripheral edge of the insulating ring 5 is formed with an annular projection 5a projecting upward and an annular projection 5b projecting downward, and the peripheral edge of the metal plate 6 is formed with the annular projection 5.
It is positioned and fixed in close contact with the inner surface of b.

A sealing plate 4 is laminated on the upper surface of the insulating ring 5. The sealing plate 4 is a circular disc made of aluminum, and the central portion thereof has a hemispherical projection 4 protruding downward.
b is formed, and this protruding portion 4b is fitted with the tubular portion 6a of the metal plate 6, and electrically connects the lead 7 and the terminal plate 3 via this fitting portion. Further, on the upper and lower surfaces of the sealing plate 4, there are thin portions 4a radially centered around the protrusion 4b.
Are formed.

Further, a Z-shaped section 4c is formed at the peripheral edge of the sealing plate 4, and the central section 4d and peripheral edge 4e of the sealing plate 4 are bounded by the Z-shaped section 4c. Can be divided into The peripheral edge of the central plane portion 4d is in close contact with the inner side surface of the annular projection 5a of the insulating ring 5, while the lower surface of the peripheral edge 4e of the sealing plate 4 is in close contact with the upper end surface of the annular projection 5a. The peripheral edge portion 4e is laminated with the peripheral edge portion of the terminal plate 3 and is caulked to the front end of the battery case 1 via the sealing gasket 2.

In the battery having the sealing structure of the first embodiment described above, for example, gas is generated and filled due to chemical change inside the battery due to progress of overcharge or short circuit, and the gas fills the inside of the battery. When the internal pressure starts to rise, as shown in the partially broken vertical sectional view of FIG.
The central portion of the is pressed toward the terminal plate 3 and moves upward.
By this movement of the central portion, the projection 4b of the sealing plate 4 is pulled out from the tubular portion 6a of the metal plate 6, and the current is cut off. At this time, since the Z-shaped section 4c is formed on the peripheral edge of the sealing plate 4, even if the peripheral edge 4e is fixed to the open end of the battery case 1, it is not affected and the sealing is performed. The central portion of the plate 4 can be easily moved upward, and this movement does not cause the peripheral edge portion 4e to be dragged inward and impair the airtightness of the sealing structure.

Further, even if the current is interrupted as described above, if gas continues to be generated inside the battery for some reason and the internal pressure further rises, a partially broken vertical sectional view of FIG. 3 is shown. As described above, the thin portion 4a of the sealing plate 4 is broken, the gas is guided toward the terminal plate 3, and is further exhausted to the atmosphere through the gas vent hole 3a, whereby the explosion of the battery is prevented.

Next, a second embodiment of the explosion-proof battery sealing structure according to the present invention will be described. The sealing structure of this embodiment is almost the same as that of the first embodiment except for the explosion-proof mechanism, so this explosion-proof mechanism will be described with reference to the partially broken vertical sectional view of FIG.

The explosion-proof mechanism includes a metal sealing plate 26 disposed below the terminal plate 27, a metal plate 24 disposed below the sealing plate 26, the metal plate 24 and the sealing plate 26. The insulating ring 25 is laminated on the peripheral portion between the two.

The lead 22 is made of aluminum, and the other end of the lead 22 attached to the power generating element 21 at one end is
It is connected by welding to an arbitrary position on the lower surface of the metal plate 24. The metal plate 24 is a circular plate made of aluminum, and gas vent holes 24a are formed at a plurality of positions thereof.

An insulating ring 25 made of polypropylene is laminated on the upper surface of the peripheral edge of the metal plate 24 to electrically insulate the peripheral edge of the sealing plate 26 from the peripheral edge of the metal plate 24.

The sealing plate 26 is a disc made of aluminum, and the peripheral edge of the sealing plate 26 is curled upward and inward to caulk the peripheral edge of the terminal plate 27. In addition, a hemispherical projection 26a protruding downward is formed at the center of the sealing plate 26, and the lower surface of the projection 26a is the upper surface of the metal plate 24 due to the elastic deformation of the sealing plate 26 downward. Is pressed against. Then, the lead 22 and the terminal board 27 are electrically connected via this pressure contact portion.

Further, on the upper and lower surfaces of the sealing plate 26, the protrusion 2
An annular thin portion 26b is formed around 6a, and an annular protrusion 26c protruding upward is formed on the outer periphery of the thin portion 26b. The protrusion 26c forms the sealing plate 2
An upward urging force acts on the central portion of 6. Then, the metal plate 24, the insulating ring 25, and the sealing plate 2 described above.
6 and the terminal plate 27 are crimped to the open end of the battery case 20 via a sealing gasket 28.

Here, the assembling method of the above-described sealing structure of the present embodiment will be described. First, as shown in the partially broken vertical sectional view of FIG. A metal plate 24, in which one end of the lead 22 is welded to an arbitrary position on the lower surface, an insulating ring 25, a terminal plate 27 caulked and integrated, and a sealing plate 26 are laminated.

Thereafter, as shown in FIG. 5B, the upper surface of the terminal plate 27 is pressed to elastically deform the sealing plate 26, and the lower surface of the protrusion 26a is brought into pressure contact with the upper surface of the central portion of the metal plate 24. Then, the open end of the battery case 20 is curled to be caulked through the gasket 28.

In the battery having the sealing structure of the second embodiment described above, since the peripheral edge of the metal plate 24 is caulked to the opening of the battery case 20 via the sealing gasket 28, the sealing structure is When an external force is applied, the conductive metal plate 24 opposes this external force, so that the metal plate 24 provides strength. Therefore, the strength of the sealing structure can be improved and the reliability is improved.

Further, since the strength of the sealing structure is improved by the metal plate 24, the insulating ring 25, the sealing plate 26, the terminal plate 2
7. The thickness of each of the sealing gaskets 28 and the thickness of the entire sealing structure can be reduced as much as possible. Therefore, the production cost can be reduced, the weight can be reduced, and the productivity can be improved.

In addition, the effective volume in the battery is increased, and the amount of electrolyte injected is increased to improve the battery performance.

Further, for example, when overcharging or short circuit progresses and a gas is generated and filled due to a chemical change inside the battery, and the internal pressure in the battery starts to rise due to the filling of the gas, a partially broken longitudinal section of FIG. As shown in the figure, the central portion of the sealing plate 26 is pressed toward the terminal plate 27 by the increase of the internal pressure and moves upward. By moving the sealing plate 26, the metal plate 24
The protruding portion 26a, which has been pressed against the upper surface of the above, is separated from the metal plate 24 at the pressed portion, and the current is cut off.

Further, even if the current is cut off as described above, if gas continues to be generated inside the battery for some reason and the internal pressure further rises, a partially broken vertical sectional view of FIG. 7 is shown. As described above, the thin portion 26b of the sealing plate 26 is broken, the gas is guided toward the terminal plate 27, and further exhausted to the atmosphere through the gas vent hole 27a, whereby the explosion of the battery is prevented.

Further, in the present embodiment, as shown in FIG. 5 described above, the terminal plate 27 is caulked by being curled by the sealing plate 26, but it is simply curled without curling.
You may make it mount on top.

[0046]

According to the present invention having the above structure, the sealing plate and the lead are not directly connected by welding, and the protrusion and the lower surface of the sealing plate of the metal plate are welded with the lead. Since the connection is made by fitting with the tubular portion or by pressing the protruding portion of the sealing plate against the upper surface of the metal plate, it is possible to perform welding management such as highly accurate welding accuracy setting like connection by welding. It becomes unnecessary, and the assembly process and process control are simplified as compared with the case where the projection of the sealing plate and the lead are directly connected by welding.

Further, since the lead can be welded to almost any position on the lower surface of the metal plate instead of the predetermined position of the sealing plate, the welding work is simplified and the assembly process and process control are further simplified.

Further, the fitting strength between the protrusion and the tubular portion is set by adjusting the shapes and materials of the protrusion of the sealing plate and the tubular portion of the metal plate in advance. it can. Therefore, compared with the case where the electrical connection and insulation between the lead and the sealing plate are caused by welding and welding breakage, a current interruption characteristic such that the current is appropriately interrupted when the inside of the battery reaches a predetermined internal pressure. This facilitates setting, reduces variations in the current interruption characteristics, further simplifies the assembly process and process control, and improves battery reliability.

Furthermore, the peripheral portion of the sealing plate is cross-section Z
In the case of the letter shape, the sealing plate can bend upward under the increased gas pressure without being restricted by the peripheral edge portion crimped at the open end of the battery case. Therefore, since the deflection can be easily set, the current cutoff characteristic can be easily set, and the variation in the current cutoff characteristic can be reduced.

Further, even if the central portion of the sealing plate moves upward due to the increased gas pressure, the peripheral edge portion is not dragged upward, so that the gasket and the peripheral portion of the sealing plate are separated from each other. Airtightness is not impaired and airtightness of the battery is not impaired. Therefore, the assembly process and process control are further simplified, and the reliability of the battery is improved.

When the peripheral portion of the metal plate is formed so as to be crimped to the open end of the battery case together with the sealing plate and the terminal plate through the sealing gasket, the metal plate is the metal case. Since the external force to the sealing portion of the battery is supported, the strength of the battery sealing structure is improved and the reliability of the battery is improved.

Further, when the gas pressure in the battery case rises above a predetermined level, the sealing plate receives the gas pressure and is urged upward so that the protrusion of the sealing plate is the cylindrical shape of the metal plate. From the upper part or separated from the upper surface of the metal plate. Therefore, when gas is generated due to overcharge or a short circuit and the gas pressure rises, the current is cut off and the temperature rise and ignition of the battery are prevented. Then, even if the gas generation is not stopped and the gas pressure is further increased after the electric current is cut off as described above, the sealing plate is broken, so that the explosion is prevented.

[Brief description of drawings]

FIG. 1 is a sectional view of a sealing structure according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional view of the sealing structure in which the protrusion 4b of the first embodiment according to the present invention is separated from the tubular portion 6a of the metal plate.

FIG. 3 is a sectional view of a sealing structure in which a thin portion 4a of the first embodiment according to the present invention is broken.

FIG. 4 is a sectional view of a sealing structure of a second embodiment according to the present invention.

FIG. 5 is a cross-sectional view of the sealing structure of the second embodiment according to the present invention, in which (a) to (c) show how the sealing part is assembled.

FIG. 6 is a cross-sectional view of a sealing structure in which a protrusion 16a of the second embodiment according to the present invention is separated from the surface of the metal plate 14.

FIG. 7 is a sectional view of a sealing structure in which a thin portion 16b of the second embodiment according to the present invention is broken.

FIG. 8 is a cross-sectional view of a conventional sealing structure.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Battery case 2 Polypropylene sealing gasket 3 Terminal plate 3a Gas vent hole 4 Aluminum sealing plate 4a Thin portion 4b Projection 4c Z-shaped cross section 4d Center plane 4e Peripheral edge 5 Polypropylene insulating ring 5a Annular projection 5b Annular protrusion 6 Aluminum metal plate 6a Cylindrical portion 6b Gas vent hole 7 Aluminum lead 8 Power generating element

Claims (3)

[Claims] 1. A power generation element housed in a battery case,
A lead extending from the power generating element, a metal terminal plate attached to the opening end of the battery case through a sealing gasket and having a gas vent hole, and electrically connected to the terminal plate below And a metal sealing plate attached to the open end of the battery case via a sealing gasket, the lower surface of the sealing plate being electrically connected to the leads and the gas pressure inside the case. In the sealing structure of the explosion-proof battery, the sealing plate is formed so as to be insulated from the lead by being biased upward under the gas pressure when the pressure rises above a predetermined level and to be broken when the gas pressure further increases. A protruding part that protrudes downward is formed in the center of the metal plate, and a conductive metal plate having a gas vent hole is interposed between the sealing plate and the lead, and the metal plate stands upright in the center part of the metal plate. Forming a tubular part, The tubular portion is fitted to the protruding portion of the sealing plate, the lower surface of the metal plate is welded to the lead to electrically connect the lead and the terminal plate, and the gas pressure in the case is predetermined. When the sealing plate is increased above, the sealing plate is formed so as to be urged upward by receiving the gas pressure thereof and the protrusion of the sealing plate is separated from the tubular portion of the metal plate. Explosion-proof battery sealing structure. 2. A power generation element housed in a battery case,
A lead extending from the power generating element, a metal terminal plate attached to the opening end of the battery case through a sealing gasket and having a gas vent hole, and electrically connected to the terminal plate below And a metallic sealing plate attached to the open end of the battery case via a sealing gasket, the sealing plate having a lower surface electrically connected to the leads and a gas pressure inside the case. In the sealing structure of the explosion-proof battery, the sealing plate is formed so as to be insulated from the lead by being pressed upward by the gas pressure when the pressure rises above a predetermined level, and to be broken when the gas pressure further increases. A protrusion protruding downward at the center of the metal plate, a conductive metal plate having a gas vent hole between the sealing plate and the lead is interposed, and the peripheral edge of the metal plate is the sealing plate. Together with the terminal board Caulking in the opening of the case through a gasket, elastically deforming the central portion of the sealing plate downward, press the protrusion of the sealing plate against the upper surface of the metal plate, and the lower surface of the metal plate with the lead. When the lead and the terminal plate are electrically connected by welding with each other, and the gas pressure in the case rises above a predetermined level, the sealing plate receives the gas pressure and is urged upward to move the sealing plate. A structure for sealing an explosion-proof battery, wherein the protrusion is formed so as to be separated from the metal plate. 3. The explosion-proof battery sealing structure according to claim 1, wherein a peripheral portion of the sealing plate is formed in a Z-shaped cross section.