JPH11111264A - Sealed battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the rupture and explosion of a sheathing can while securely cutting off the current in the case where pressure inside of the sheathing can is raised by abnormality. SOLUTION: In a sealed battery, an opening of a sheathing can for housing power generating elements 3 is sealed with a seal body 2 including an outer terminal plate 7 having a gas vent hole 7a, an inner terminal plate 9 having a gas vent hole 7a and a safety valve plate 8 interposed between both the terminal plates, and the inner terminal plate 9 and the safety valve 8 are bonded to each other at a central part of the inner terminal plate 9 and the safety valve plate 8, and a peripheral part of the bonding part of the inner terminal plate 9 and the safety valve plate 8 is provided with a thin wall part 8a. In this sealed battery, the outer terminal plate 7 and the safety valve plate 8 are tightly fitted to the sheathing can 1 at a peripheral edge of the outer terminal plate 7 and the safety valve plates 8, and while a peripheral edge of the inner terminal plate 9 is formed as a free end.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a sealed battery having a current interrupting function and an explosion-proof function.

[0002]

2. Description of the Related Art In a sealed battery using a non-aqueous electrolyte such as a lithium battery or a lithium ion battery, if a power generating element in an outer can is overcharged or a large current flows due to misuse, the non-aqueous battery is not used. The electrolytic solution is decomposed to generate gas, and the pressure inside the outer can increases, which may cause the battery to burst or explode.

[0003] Therefore, in a conventional sealed battery,
As an explosion-proof measure when such an abnormality occurs, for example, a measure described in JP-A-7-105933 is taken.

FIG. 4 is a schematic vertical sectional view of such a sealed battery. In FIG. 4, reference numeral 61 denotes an outer can, and 62 denotes a sealing body attached to an opening of the outer can 61. A power generation element 63 is housed inside the outer can 61. The power generating element 63 has a configuration in which a laminate of a positive electrode 64, a separator 65, and a negative electrode 66 is spirally wound and filled with a non-aqueous electrolyte.

On the other hand, the sealing body 62 has a safety valve plate 68 interposed between an inner terminal plate 69 having a gas vent hole 69a and an outer terminal plate 67 also having a gas vent hole 67a. The central portion 69b of the inner terminal plate 69 is joined by welding and the safety valve plate 68 of the inner terminal plate 69 is joined.
A thin portion 69c is provided on the outer peripheral portion of the joining portion with the above. These inner terminal plate 69, outer terminal plate 67, safety valve plate 68
Are made of a conductive material.
1 is fixed via an electrically insulating gasket 70, and an electrically insulating gasket 71 is also interposed between the safety valve plate 68 and the inner terminal plate 69. The inner surface of the inner terminal plate 69 and the positive electrode 64 of the power generating element 63 are connected to the lead wire 74.
And a current flows from the power generating element 63 to the outer terminal plate 67 via the inner terminal plate 69 and the safety valve plate 68.

In the above configuration, when gas is generated due to the abnormality of the power generation element 63 and the pressure in the outer can 61 rises, the gas enters through the gas vent hole 69a of the inner terminal plate 69 and pushes up the safety valve plate 68, and The thin portion 69c provided on the terminal plate 69 is broken or the joint between the safety valve plate 68 and the inner terminal plate 69 is peeled off, so that an abnormally large current flows to the outer terminal plate 67. When the pressure further increases, the safety valve plate 6
8, the gas is released to the outside from the gas vent hole 67a of the outer terminal plate 67, and the explosion of the outer can 61 is prevented.

As described above, in order to reliably shut off the current when the pressure in the outer can rises due to an abnormality, the strength of the thin portion 69c provided on the inner terminal plate 69 must be appropriately set, and The joining strength between the terminal plate 69 and the safety valve plate 68 needs to be selected to a required strength.

However, as described above, the inner terminal plate 69 and the safety valve plate 68 of the conventional sealed battery are fixed together with the outer terminal plate 67 by the outer can 61 via the gasket 70 at the peripheral edge and fixed. , The inner terminal plate 6
Even if the strength of the thin portion 69c provided in 9 is appropriately set, or the inner terminal plate 69 and the safety valve plate 68 are joined with a required strength, the inner terminal plate 69, the safety valve plate 68, When the outer terminal plate 67 is crimped at the peripheral portion, a distortion is generated in the outer terminal plate 67, and a strain stress is generated in the thin portion 69c of the inner terminal plate 69 or a joint portion between the inner terminal plate 69 and the safety valve plate 68, and the thin portion 69c A phenomenon occurs in which the strength becomes unstable, breaks occur, or the bonding strength of the bonding portion 69b becomes unstable or peels off. When the strength of the thin portion and the bonding strength become unstable, the thin portion is broken at the time of abnormality or the peeling mechanism of the bonding portion does not operate reliably, thereby lowering the safety of the battery. Further, when the thin portion is torn or the joint is peeled during assembly, the battery is not a product, and there is a problem that productivity is reduced.

[0009]

DISCLOSURE OF THE INVENTION The present invention relates to a sealed battery capable of more reliably shutting off the current when the pressure inside the outer can rises due to an abnormality and preventing the outer can from bursting or exploding. The purpose is to provide.

[0010]

In order to achieve the above-mentioned object, the present invention provides an outer can having a power generating element, wherein an outer terminal plate having a gas vent hole and an inner terminal plate having a gas vent hole are provided. And sealing with a sealing body including a safety valve plate interposed between these two terminal plates, and joining the inner terminal plate and the safety valve plate at a central portion of the inner terminal plate and the safety valve plate, and In a sealed battery in which a thin portion is provided at an outer peripheral portion of a joint portion of an inner terminal plate and a safety valve plate, the outer terminal plate and the safety valve plate are attached to the outer can at the peripheral portions of the outer terminal plate and the safety valve plate. The inner terminal plate is configured to be free and the peripheral portion of the inner terminal plate is configured as a free end.

[0011] Between the safety valve plate and the inner terminal plate,
It is preferable to interpose a space ring having electric insulation and airtightness.

It is preferable that an elastic body having electrical insulation is interposed between the safety valve plate and the inner terminal plate and inside the space ring. As the elastic body having electrical insulation, an electrically insulating material such as rubber or plastic, or a material having electrical insulation and elasticity, such as a spring coated with an electrically insulating material, can be used.

Further, the inner terminal plate has a central portion formed in a convex portion, the safety valve plate has a flat central portion, and the inner terminal plate and the safety valve plate are connected to each other by the inner terminal plate and the safety valve plate. It is preferable to be joined at the center.

Furthermore, it is preferable that an electric resistor ring having a positive temperature coefficient is interposed between the outer terminal plate and the safety valve plate. An electric resistor (Positive) having a positive temperature coefficient that is effective for maintaining safety during abnormal temperature rise
eTemperatureCoefficient,
Hereafter, PTC is a resistor whose electric resistance increases as the temperature rises. Such PTCs include:
For example, there is one made of a mixture of conductive carbon and a polymer such as polyolefin or fluororesin.

The sealed battery of the present invention is effective as a battery having a high energy density, such as a lithium battery or a lithium ion battery, or a secondary battery that can be repeatedly used by charging.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in more detail based on embodiments shown in the drawings.

FIG. 1 is a schematic longitudinal sectional view of a sealed battery according to one embodiment of the present invention.

In FIG. 1, an outer can 1 is made of a conductive material such as stainless steel or nickel-plated carbon steel, and houses a power generating element 3 therein. The power generating element 3 is formed by laminating a sheet-shaped positive electrode 4, a separator 5, and a negative electrode 6 in a spiral, for example,
It is configured to be filled with a non-aqueous electrolyte.

At the opening of the outer can 1, a partition plate 14 for partitioning between the upper surface of the power generating element 3 and the sealing body 2 is provided, and the partition plate 14 is provided with a gas vent hole 14a for venting gas. I have.

The sealing body 2 has a safety valve plate 8 interposed between an outer terminal plate 7 having a gas vent hole 7a and an inner terminal plate 9 having a gas vent hole 9a. The outer terminal plate 7, the safety valve plate 8, and the inner terminal plate 9 are all made of a conductive material such as stainless steel, nickel-plated carbon steel, or aluminum. The sealing body 2 is caulked to the opening of the outer can 1 via a gasket 13 made of an insulating material such as rubber or plastic.

The outer terminal plate 7 and the safety valve plate 8 are integrated at a peripheral edge thereof by a caulking ring 12 of a tightening element.

The inner terminal plate 9 has a free edge at the periphery thereof,
A central portion 9b of the inner terminal plate 9 is joined to a central portion of the safety valve plate 8, and a thin portion 9c is provided at an outer peripheral portion of a joint portion of the inner terminal plate 9 with the safety valve plate 8. When the central portion of the inner terminal plate 9 is formed in the convex portion 9b, the inner terminal plate 9 can be easily welded to the safety valve plate 8 and can be firmly fixed by welding. Therefore, the thin portion 9c of the inner terminal plate 9 can be surely broken without the joint portion being peeled off when an abnormality occurs. Further, it is preferable to provide a flange-shaped guide portion 9d at the peripheral portion of the inner terminal plate 9, so that the inner terminal plate 9 and the safety valve plate 8 can be easily positioned at the time of assembling the sealing body.

The inner terminal plate 9 and the safety valve plate 8 can be joined by welding such as ultrasonic welding or laser welding, and the welding strength is set to be equal to the breaking strength of the thin portion 9c provided on the inner terminal plate 9. Preferably, the breaking strength of the thin portion 9c is set to be weaker than the breaking strength of the safety valve plate 8.

The safety valve plate 8 is preferably formed to have a flat central portion, the shape of the safety valve plate 8 is simplified, the tearing strength of the safety valve plate 8 can be selected to a required strength, and the tearing accuracy is improved. Further, the safety valve plate 8 may be a dish shape, and even if the peripheral portion is swaged, no distortion stress acts on the joint portion between the safety valve plate 8 and the inner terminal plate 9, so that a stable electric circuit can be formed. As the safety valve plate 8, besides chemically stable stainless steel, an elastic conductor such as aluminum or spring steel or a laminate of an elastic conductor film and a highly conductive metal film such as aluminum can be used. . In the safety valve plate 8,
A thin portion (groove) 8a having an arbitrary shape such as a circle, a polygon, and an H shape is provided on the surface. The thin portion (groove) 8a is for the safety valve plate 8 to be easily torn when the pressure in the outer can 1 increases due to an abnormality of the power generation element 3. Further, at the same time when the thin portion 9c provided on the inner terminal plate 9 is broken,
Alternatively, the tearing strength of the safety valve plate 8 is set so that the safety valve plate 8 is torn after the breakage.
It is preferable that the breaking strength is set to be equal to or higher than the breaking strength.

The caulking ring 12 is made of a conductive material such as stainless steel, nickel-plated carbon steel or aluminum, or is covered with an electrically insulating material such as rubber or plastic or an electrically insulating material. Good.

Further, a space ring 11 having electrical insulation and airtightness is interposed between the caulking ring 12 and the outer terminal plate 7 and between the caulking ring 12 and the safety valve plate 8 so as to interpose the outer terminal plate 7. , Safety valve plate 8, space ring 11
May be integrated by the caulking ring 12.

Space part 11a of space ring 11
Are provided for keeping the space between the safety valve plate 8 and the inner terminal plate 9, and the inner terminal plate 9 is configured not to be caulked.

The space ring 11 is made of a material having electrical insulation and airtightness, such as rubber or plastic, or
A metal material or the like coated with such an electrically insulating and airtight material can be used.

By interposing the PTC ring 10 between the outer terminal plate 7 and the safety valve plate 8, when the temperature of the power generating element 3 rises due to an abnormality, the electric resistance of the PTC ring 10 increases, and This is preferable because the current can be reduced or cut off.

The guide portion 11b of the space ring 11 and the guide portion 9d of the inner terminal plate 9 guide the inner terminal plate 9 to the center of the safety valve plate 8 to facilitate positioning. Further, the inner terminal plate 9 can be temporarily fixed to the space ring 11 in a loosely fitted state, and the assemblability and mass productivity of the battery can be improved.

One end of the lead wire 15 is connected to the positive electrode 4 of the power generating element 3 via a gas vent hole 14 a of the partition plate 14. The other end is welded to the lower surface of the inner terminal plate 9 by ultrasonic welding, laser welding, or the like.

FIG. 2 is a schematic longitudinal sectional view of a main part of a sealed battery according to another embodiment of the present invention. The gasket 17 made of an electrically insulating material has the gasket 13, the space ring 11, and the caulking ring 12 shown in FIG. 1 integrated with each other, and has respective functions. Thereby, the number of parts can be reduced.

The outer terminal plate 7 and the safety valve plate 8 are connected to the gasket 1
The gasket 17 is fixed by a claw portion 17 a at a peripheral edge rising portion.

FIG. 3 is a schematic longitudinal sectional view of a main part of a sealed battery according to still another embodiment of the present invention. Inner terminal board 9
An elastic body 16 having electrical insulation is accommodated in a gap formed by the space 11a with a space ring 11 interposed between the space ring 11 and the safety valve plate 8. The elastic body 16 is for improving the breaking accuracy of the thin portion 9c provided on the inner terminal plate 9 and having a current interrupting function. As a result, after breaking the current by breaking the thin portion 9c provided on the inner terminal plate, it is possible to prevent the broken portion of the inner terminal plate 9 from coming into contact again, reliably perform the current breaking, and reduce the battery safety. Can be prevented. As the elastic body having electrical insulation, an elastic body having electrical insulation and elasticity, such as an electrical insulating material such as rubber or plastic, or a spring coated with an electrical insulating material, can be used.

[0035]

According to the present invention, the outer terminal plate and the safety valve plate are tightly attached to the outer can at the peripheral portions of the outer terminal plate and the safety valve plate, and the inner terminal plate is free from the inner terminal plate. The breaking strength of the thin part can be set appropriately,
In addition, since no strain stress acts on the thin portion even after the battery is assembled, its breaking strength does not change. For this reason, when an abnormality occurs, the thin portion can be reliably broken, and the current can be interrupted.

When a space ring having electrical insulation and airtightness is interposed between the safety valve plate and the inner terminal plate, the safety valve plate and the inner terminal plate are electrically insulated, and
The nonaqueous electrolyte can be sealed in the outer can.

Further, by providing an elastic body having electrical insulation between the safety valve plate and the inner terminal plate and inside the space ring, the breaking accuracy of the thin portion which interrupts the current when an abnormality occurs is improved. As a result, it is possible to prevent re-contact of the broken portion of the inner terminal plate after current interruption, thereby preventing a decrease in battery safety due to re-contact.

Further, by forming the shape of the safety valve plate at the joint between the safety valve plate and the inner terminal plate flat, the shape of the safety valve plate is simplified, the tearing strength of the safety valve plate is stabilized, and the tearing accuracy is improved. be able to.

By forming the central portion of the inner terminal plate as a convex portion, it can be easily welded to the safety valve plate, can be firmly joined, and the breaking strength of the thin portion can be stabilized. For this reason, when an abnormality occurs, the thin portion can be reliably broken.

Further, PT is provided between the outer terminal plate and the safety valve plate.
By interposing the C-ring, when the temperature of the power generating element rises due to an abnormality, the electric resistance of the PTC ring increases and the current to the external terminal plate can be reduced or cut off.

[Brief description of the drawings]

FIG. 1 is a schematic longitudinal sectional view of a sealed battery according to one embodiment of the present invention.

FIG. 2 is a schematic longitudinal sectional view of a main part of a sealed battery according to another embodiment of the present invention.

FIG. 3 is a schematic longitudinal sectional view of a main part of a sealed battery according to still another embodiment of the present invention.

FIG. 4 is a schematic longitudinal sectional view of a conventional sealed battery.

[Explanation of symbols]

1: exterior can 2: sealing body 3: power generation element 4: positive electrode 5: separator 6: negative electrode 7: outer terminal plate 7a: gas vent hole 8: safety valve plate 8a: thin portion (groove) 9: inner terminal plate 9a: gas Hole 9b: convex portion 9c: thin portion 9d: guide portion 10: resistor ring (PTC ring) having a positive temperature coefficient 11: space ring 11a: space portion 11b: guide portion 12: caulking ring 13: gasket 14: Partition plate 14a: Gas vent hole 15: Lead wire 16: Elastic body 17: Gasket 17a: Nail

Claims (6)

[Claims] An opening of an outer can housing a power generating element is formed by an outer terminal plate having a gas vent hole, an inner terminal plate having a gas vent hole, and a safety valve plate interposed between these two terminal plates. And sealing the inner terminal plate and the safety valve plate at the center of the inner terminal plate and the safety valve plate, and thinning the outer peripheral portion of the joint between the inner terminal plate and the safety valve plate. The outer terminal plate and the safety valve plate are tightly attached to the outer can at the peripheral portions of the outer terminal plate and the safety valve plate, and the peripheral portion of the inner terminal plate is a free end. A sealed battery characterized by the following. 2. The sealed battery according to claim 1, wherein a space ring having electrical insulation and airtightness is interposed between the safety valve plate and the inner terminal plate. 3. The hermetic seal according to claim 2, wherein an elastic body having electrical insulation is interposed between the safety valve plate and the inner terminal plate and inside the space ring. Type battery. 4. The inner terminal plate has a central portion formed in a convex portion,
4. The safety valve plate according to claim 1, wherein a central portion is formed flat, and the inner terminal plate and the safety valve plate are joined at a center portion between the inner terminal plate and the safety valve plate. A sealed battery as described in Crab. 5. The hermetic mold according to claim 1, wherein an electric resistor ring having a positive temperature coefficient is interposed between said outer terminal plate and said safety valve plate. battery. 6. The sealed battery according to claim 1, which is a lithium battery, a lithium ion battery, or a secondary battery.