JPH1092407A - Sealed battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To break current surely, and discharge inside gas outward so as to prevent the explosion of an armor can when the internal pressure of a battery rises by fitting a cleavable shutoff valve between a safety valve and a sealing plate. SOLUTION: The thin-thickness portions of a safety valve 9 and a shutoff valve 15 are made to be easily cloven when gas is generated resulting from the disorder of a power generating element 3 so that the internal pressure rises rapidly. A protrusion portion 15a having a predetermined breaking strength is welding joined to a sealing plate 7 by ultrasonic wave, laser or the like in a central portion of the shutoff valve 15. The protrusion portion 15a is, for example, long, narrow, and bar-like, and the shutoff valve 15 is set to such strength as the same is immediately broken when the battery internal pressure rises and reaches certain pressure so that current is surely broken. After the cleavage of the shutoff valve 15, the internal pressure is applied to a safety valve 9 this time so that the safety valve 9 is cloven.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sealed battery having an explosion-proof function.

[0002]

2. Description of the Related Art In a secondary battery using a nonaqueous electrolyte such as a lithium battery or a lithium ion battery, a power generation element housed in an outer can is overcharged or a large current flows due to misuse. If this occurs, the non-aqueous electrolyte solution is decomposed to generate gas, which may increase the internal pressure in the sealed outer can and cause the battery to burst.

For this reason, conventional sealed batteries are provided with an explosion-proof measure in the event of the above-described abnormality, for example, as shown in FIG.
It has been proposed to provide a mechanism as shown in FIG.

FIG. 16 is a longitudinal sectional view of a sealing portion of a conventional sealed battery. In FIG. 16, 61 is an outer can, 6
Reference numeral 2 denotes a sealing body attached to the opening end of the outer can 61. The power generation element 63 is housed inside the outer can 61, and the power generation element 63 is configured such that a laminate of the positive electrode 64, the separator 65, and the negative electrode 66 is spirally wound and filled with a nonaqueous electrolyte. I have. On the other hand, the sealing body 62 has the same gas vent holes 6 as the sealing plate 67 provided with the gas vent holes 67a.
A safety valve 69 is interposed between the battery lid 68 and the battery lid 68 provided with the battery 8a.

The sealing plate 67, the battery cover 68, and the safety valve 6
9 is made of a conductive material, so that it is fixed to the opening end of the outer can 61 via an insulating gasket 70, and the outer periphery of the battery lid 68, the safety valve 69 and the sealing plate 6
An insulating gasket 71 is also interposed between the outer periphery of the gasket 7. In addition, a lead 72 is connected between the inner surface of the sealing plate 67 and the positive electrode 64 of the power generating element 63, and a current flows from the power generating element 63 to the battery lid 68 via the sealing plate 67 and the safety valve 69.

In the above configuration, when gas is generated due to an abnormality of the power generation element 63 and the internal pressure in the outer can 61 rises rapidly, the gas enters through the gas vent hole 67a of the sealing plate 67 and pushes up the safety valve 69, and the chain line Sealing plate 6 as shown by
7, the flow of the abnormally large current to the battery lid 68 is blocked. Further, the safety valve 69 is opened by the rapid rise of the internal pressure, and the gas is released to the outside through the gas vent hole 68a of the battery lid 68, so that the explosion of the outer can 61 is prevented.

That is, in the above conventional structure, the safety valve 6
9 and the sealing plate 67 are connected in a pressed state at their contact points to form an electric circuit, and the circuit is cut off by being deformed and separated. However, since the performance of the battery itself is affected by the electric resistance, particularly the internal resistance of the lithium battery, the connection in a pressed form has the disadvantage that the electric resistance is generated and the battery performance is not obtained. Therefore, it is necessary to mainly consider connection by welding instead of connection in a pressed form.

In Japanese Patent Application Laid-Open Nos. 2-112151 and 2-28863, a lead wire is connected to a rupturable plate (safety valve) by welding, and when the internal pressure increases, the rupturable plate is disconnected from the lead wire. It is described that the current is cut off by cutting off.However, in the sealed battery of this structure, the rupture plate is separated from the lead wire because the connection strength is adjusted by the welding strength of the lead wire. It is difficult to control the connection strength with high accuracy. That is, if the connection strength varies, the lead wire cannot be disconnected even if the internal pressure increases, or the current is interrupted when the internal pressure is low.

[0009]

An object of the present invention is to prevent the explosion of an outer can by reliably shutting off current and discharging internal gas to the outside when an abnormality occurs in the power generating element and the internal pressure of the battery rises. It is an object of the present invention to provide a sealed battery.

[0010]

The sealed battery according to the present invention that achieves the above object has the following configuration. (1) In a sealed battery in which a sealing body in which a rupturable safety valve is interposed between a battery lid having a gas vent hole and a sealing plate is attached to an open end of an outer can containing a power generating element. A sealed battery, wherein a rupturable shut-off valve is mounted between the safety valve and the sealing plate.

(2) The shut-off valve is provided with a projection having a predetermined breaking strength so as to protrude toward the sealing plate, and the projection is connected to the sealing plate by welding or penetrates a hole provided in the sealing plate. The sealed battery according to the above (1), wherein the battery is welded to the lead plate.

(3) The sealed battery according to (2), wherein the strength of a portion of the sealing plate or the lead plate to which the projection is welded is partially reduced.

(4) The shut-off valve according to (1), wherein a convex portion having a predetermined breaking strength is provided so as to protrude toward the sealing plate, and the convex portion is caulked to the sealing plate. Sealed battery.

(5) The sealing plate is characterized in that a convex portion having a predetermined breaking strength is provided so as to project toward the shutoff valve, and the convex portion is welded to the shutoff valve. The sealed battery as described.

(6) The sealed battery according to any one of (2) to (5), wherein a cutout is provided in the convex portion.

(7) The sealed battery according to (1), wherein the shut-off valve and the sealing plate are joined by a conductive member having a predetermined breaking strength.

(8) The sealed battery according to the above (7), wherein the portion of the sealing plate to which the conductive member is joined is partially reduced in strength.

(9) The sealed battery according to the above (7) or (8), wherein the conductive member is a low melting point metal or alloy.

(10) The conductive member is formed in a cap shape provided with a flange portion, penetrates a sealing plate, and the top side of the cap shape is joined to a shutoff valve, and the flange side is joined to a sealing plate. The sealed battery according to any one of the above (7) to (9).

(11) PT between the battery lid and the safety valve
(1) to (10), wherein C is interposed.
The sealed battery according to any one of the above.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below with reference to the embodiments shown in the drawings.

In the sealed battery shown in FIG.
Is made of a conductive material such as stainless steel or nickel-plated carbon steel, and houses the power generation element 3 therein. The power generating element 3 is configured by stacking a sheet-like positive electrode 4, a separator 5, and a negative electrode 6 in a spiral shape, for example, and filling a non-aqueous electrolyte therein.

At the open end of the outer can 1, there is provided a partition plate 13 for partitioning from the upper surface of the power generating element 3, and the partition plate 13 is provided with a partition plate hole 13a for venting gas. I have.

The sealing body 2 has one or more gas vent holes 7.
a safety valve 9 and a shutoff valve 1 between a sealing plate 7 provided with a. and a battery lid 8 also provided with one or a plurality of gas vent holes 8a.
5 are interposed. The sealing plate 7, the battery lid 8, the safety valve 9, and the shutoff valve 15 are all made of a conductive material such as stainless steel, nickel-plated carbon steel, or aluminum. It is fixed by caulking through a gasket 10 made of an insulating material such as rubber or plastic.

The safety valve 9 and the shutoff valve 15 may be made of 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. The safety valve 9 and the shut-off valve 15 are not provided with vent holes as provided in the sealing plate 7 and the battery cover 8, respectively, and have any surface such as a circle, a polygon, and an H-shape. The thin portions in which the grooves 9a and 15b are cut are formed. The thin portions of the safety valve 9 and the shutoff valve 15
When a gas is generated due to an abnormality of the power generating element 3 and the internal pressure rises rapidly, the gas is easily split.

A convex portion 15a having a predetermined breaking strength is provided at the center of the shut-off valve 15 so as to protrude toward the sealing plate 7, and the convex portion 15a is welded and connected to the sealing plate 7 by ultrasonic wave, laser or the like. is there. The protruding portion 15a is elongated, for example, in a rod shape, and is set to have a strength such that when the internal pressure of the battery increases and the shutoff valve 15 reaches a certain pressure, the strength is set so as to be broken. I do.

The breaking strength of the projection 15a and the tearing strength of the cutoff valve 15 are set so that the cutoff valve 15 is deformed and the cutoff valve 15 is split after the protrusion 15a is broken.

After the cutoff of the shutoff valve 15, this time the safety valve 9
, The safety valve 9 is deformed and the safety valve 9 is torn. That is, the present invention is characterized in that the function of shutting off the circuit and the function of opening the safety valve are completely separated.

Therefore, the safety valve 9 and the shut-off valve 15 are formed of different members having different tearing strengths, and the shut-off valve 15 is set so as to be split at a lower pressure than the safety valve 9.
The convex portion 15a is set to be broken at a pressure lower than that of the shutoff valve 15.

A PTC 11 is provided between the battery cover 8 and the safety valve 9.
Is inserted. PTC stands for Positive Temperature Coefficient Resistor (Posi
tive Temperature Coefficient), that is, a material whose electrical resistance increases as the temperature increases, and this material itself is known. Thus, the battery cover 8 and the safety valve 9
And the power generation element 3
When the temperature rises due to an abnormality, the electric resistance of the PTC 11 increases, and the current to the battery lid 8 is cut off.

A lead 14 is welded to the inner surface of the sealing plate 7, and the other end is connected to the positive electrode 4 of the power generating element 3 via a partition plate hole 13 a of the partition plate 13. The current generated by the power generating element 3 flows through the sealing plate 7, the convex portion 15 a, the shutoff valve 15, the safety valve 9, and the PCT 11 via the lead 14 to the battery cover 8 serving as a terminal.

In the sealed battery having the above structure, when gas is generated due to an abnormality of the power generating element 3 and the internal pressure rises rapidly, the gas passing through the gas vent hole 7 a of the sealing plate 7 acts on the inside of the shut-off valve 15. Then, the projection 15a of the shut-off valve 15 is broken to cut off the electric circuit, and further, the shut-off valve 15 is deformed and the shut-off valve 15 is opened. When the cutoff valve 15 is opened, the gas acts on the inside of the safety valve 9, breaks the safety valve 9, and is released to the outside through the gas vent hole 8 a of the battery lid 8, thereby reliably preventing the battery from exploding. When the temperature of the power generating element 3 rises due to an abnormality, the battery cover 8 and the safety valve 9
, The electric resistance of the PTC 14 inserted therebetween increases, and the current to the battery lid 8 is cut off. The present invention relates to the projection 15
By breaking a and breaking off the shut-off valve 15, the circuit was reliably cut off, and then the safety valve 9 was cut off, so that the gas could be reliably discharged to the outside.

FIG. 2 shows another embodiment of the present invention.

In this embodiment, in the structure of the embodiment described with reference to FIG. 1, a notch 16 for reducing the sectional area of the projection 15a is provided on the surface of the projection 15a of the shut-off valve 15 as shown in FIG. The notch 16 is surely broken at the portion.

FIG. 3 shows still another embodiment of the present invention.

In this embodiment, in the structure of the embodiment described with reference to FIG. 1, a hole is provided at the center of the sealing plate 7, and the projection 15a of the shutoff valve 15 is inserted through the hole at the center of the sealing plate 7. It is welded and connected to the lead plate 17.

FIG. 4 shows still another embodiment of the present invention.

In this embodiment, in the structure of the embodiment described with reference to FIG. 3, a notch 16 is provided in the convex portion 15a of the shut-off valve 15 as shown in FIG.

FIG. 5 shows still another embodiment of the present invention.

In this embodiment, in the structure of the embodiment described with reference to FIG. 1, instead of welding and connecting the projection 15a to the sealing plate 7, the projection 15a of the shutoff valve 15 is crimped to the sealing plate 7. Things.

FIG. 6 shows still another embodiment of the present invention.

In this embodiment, a cutout 16 is provided in the convex portion 15a of the shutoff valve 15 as shown in FIG. 6 in the structure of the embodiment described with reference to FIG.

FIG. 7 shows still another embodiment of the present invention.

In this embodiment, in the structure of the embodiment described with reference to FIG. 1, the projection 15a is welded and connected to the sealing plate 7, and the sealing plate 7 is provided with a portion 7c having a partially weakened strength. It is a thing. If the projection 15a does not break for any reason, the safety is further ensured so that it breaks at the weakened portion 7c of the sealing plate 7.

FIG. 8 shows still another embodiment of the present invention.

In this embodiment, a cutout 16 is provided in the projection 15a of the shutoff valve 15 as shown in FIG. 8 in the structure of the embodiment described with reference to FIG.

FIG. 9 shows still another embodiment of the present invention.

In this embodiment, a hole is provided at the center of the sealing plate 7 in the structure of the embodiment described with reference to FIG. 3, and the projection 15a of the shutoff valve 15 is inserted through the hole at the center of the sealing plate 7. In the one welded and connected to the lead plate 17, the lead plate 17 is provided with a portion 17a whose strength is partially reduced. If the protrusion 15a does not break for some reason, the safety is further ensured so that the protrusion 15a breaks at the weakened portion 17a of the lead plate 17.

FIG. 10 shows still another embodiment of the present invention.

In this embodiment, a cutout 16 is provided in the projection 15a of the shutoff valve 15 as shown in FIG. 10 in the structure of the embodiment described with reference to FIG.

FIG. 11 shows still another embodiment of the present invention.

In this embodiment, the cut-off valve 15
Instead of providing a, a convex portion 7b having a predetermined breaking strength is provided at the center of the sealing plate 7 so as to protrude toward the shutoff valve 15 side,
The projection 7b is welded to the shut-off valve 15 by ultrasonic, laser, etc.
Connected.

The protruding portion 7b is elongated, for example, in the shape of a rod, and is set to have such a strength that it breaks when the internal pressure of the battery rises and the shutoff valve 15 reaches a certain pressure. Cut off the current.

The breaking strength of the projection 7b and the tearing strength of the cutoff valve 15 are set so that the cutoff valve 15 is deformed and the cutoff valve 15 is split after the protrusion 7b is broken.

FIG. 12 shows still another embodiment of the present invention.

In this embodiment, in the structure of the embodiment described with reference to FIG. 11, a notch 1 for reducing the cross-sectional area of the projection is provided on the surface of the projection 7b of the sealing plate 7 as shown in FIG.
6 is provided so as to be surely broken at the notch 16.

FIG. 13 shows still another embodiment of the present invention.

In this embodiment, instead of providing the projections 15a and 7b, the shut-off valve 15 and the sealing plate 7 are welded and connected by a conductive member 18 having a predetermined breaking strength by ultrasonic waves, laser, or the like. . The conductive member 18 is, for example, elongated in a rod shape, and is set to have a strength such that when the internal pressure of the battery rises and the shutoff valve 15 reaches a certain pressure, the strength of the conductive member 18 is broken so that the current is reliably shut off. I do.

The conductive member 18 may be a member other than the shut-off valve 15 and the sealing plate 7, such as a low-melting metal or alloy, or a metal or alloy having low strength.

After the breakage of the conductive member 18, the shut-off valve 15
The breaking strength of the conductive member 15 and the breaking strength of the shutoff valve 15 are set so that the cutoff valve 15 is deformed and the cutoff valve 15 is split.

FIG. 14 shows still another embodiment of the present invention.

In this embodiment, in the structure of the embodiment described with reference to FIG. 13, the sealing plate 7 is provided with a thin portion 7c whose strength is partially reduced. If the conductive member 18 is not broken for some reason, the safety is further ensured so that the conductive member 18 is broken at the weakened portion 7c of the sealing plate 7.

FIG. 15 shows still another embodiment of the present invention.

In this embodiment, the shape of the conductive member 18 is formed in the shape of a cap provided with a flange, and the top side of the cap is penetrated through the sealing plate and joined to the shut-off valve. It is provided by bonding to a sealing plate. Since the inside of the cap body is hollow, the conductive member 18 is more easily broken, and welding is facilitated because of the presence of the flange.

[0065]

As described above, according to the present invention, when the internal pressure of the battery rises, the shut-off valve for shutting off the circuit is provided separately from the safety valve that releases the internal gas pressure by cleavage. The electric circuit is reliably shut off regardless of the welding strength, and the current is reliably shut off and the operation of the safety valve is stabilized. In addition, when the shutoff valve reaches a certain pressure, the convex portion is broken, so that the current is reliably shut off.
Also, even when the projection does not break, the current is reliably cut off by opening the cutoff valve. Further, by breaking the safety valve, the internal gas can be reliably released to the outside, and the explosion of the battery can be prevented. Further, by interposing the PTC between the battery cover and the safety valve, it is possible to increase the electric resistance when the temperature of the power generation element rises due to an abnormality, and cut off the current to the battery cover. Therefore, when an abnormality occurs in the power generating element and the internal pressure of the battery rises, the current can be reliably shut off and the internal gas is released to the outside, so that the explosion of the outer can can be prevented.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a sealing body of a sealed battery according to an embodiment of the present invention.

FIG. 2 is a longitudinal sectional view of a sealing body of a sealed battery according to another embodiment of the present invention.

FIG. 3 is a longitudinal sectional view of a sealing body of a sealed battery according to still another embodiment of the present invention.

FIG. 4 is a longitudinal sectional view of a sealing body of a sealed battery according to still another embodiment of the present invention.

FIG. 5 is a longitudinal sectional view of a sealing body of a sealed battery according to still another embodiment of the present invention.

FIG. 6 is a longitudinal sectional view of a sealing body of a sealed battery according to still another embodiment of the present invention.

FIG. 7 is a longitudinal sectional view of a sealing body of a sealed battery according to still another embodiment of the present invention.

FIG. 8 is a longitudinal sectional view of a sealing body of a sealed battery according to still another embodiment of the present invention.

FIG. 9 is a longitudinal sectional view of a sealing body of a sealed battery according to still another embodiment of the present invention.

FIG. 10 is a longitudinal sectional view of a sealing body of a sealed battery according to still another embodiment of the present invention.

FIG. 11 is a longitudinal sectional view of a sealing body of a sealed battery according to still another embodiment of the present invention.

FIG. 12 is a longitudinal sectional view of a sealing body of a sealed battery according to still another embodiment of the present invention.

FIG. 13 is a longitudinal sectional view of a sealing body of a sealed battery according to still another embodiment of the present invention.

FIG. 14 is a longitudinal sectional view of a sealing portion of a sealed battery according to still another embodiment of the present invention.

FIG. 15 is a longitudinal sectional view of a sealing body of a sealed battery according to still another embodiment of the present invention.

FIG. 16 is a longitudinal sectional view of a sealing body portion of a conventional sealed battery.

[Explanation of symbols]

 1: exterior can 2: sealing body 3: power generating element 7: sealing plate 7a: gas vent hole 7b: convex portion 7c: weak portion 8: battery lid 8a: gas vent hole 9: safety valve 9a: groove portion 10: gasket 11: PTC 12: insulating gasket 13: partition plate 13a: partition plate hole 14: lead 15: shutoff valve 15a: convex portion 16: notch 17: lead plate 17a: weak portion 18: conductive member

Claims (12)

[Claims] 1. An opening end of an outer can containing a power generating element,
In a sealed battery in which a sealing body having a rupturable safety valve interposed between a battery lid having a gas vent hole and a sealing plate was mounted, a cleavable shutoff valve was mounted between the safety valve and the sealing plate. A sealed battery comprising: 2. The shut-off valve is provided with a projection having a predetermined breaking strength so as to protrude toward the sealing plate, and the projection is connected to the sealing plate by welding or through a hole provided in the sealing plate. The sealed battery according to claim 1, wherein the battery is welded to the lead plate. 3. The sealed battery according to claim 2, wherein a strength of a portion of the sealing plate or the lead plate to which the projection is welded is partially reduced. 4. The closed mold according to claim 1, wherein a convex portion having a predetermined breaking strength is provided on the shut-off valve so as to protrude toward the sealing plate, and the convex portion is caulked to the sealing plate. battery. 5. The sealing plate according to claim 1, wherein a projection having a predetermined breaking strength is provided so as to project toward the shutoff valve, and the projection is welded to the shutoff valve. Sealed battery. 6. The sealed battery according to claim 2, wherein a notch is provided in the projection. 7. The sealed battery according to claim 1, wherein the shut-off valve and the sealing plate are joined by a conductive member having a predetermined breaking strength. 8. A part of the sealing plate to which the conductive member is joined is partially reduced in strength.
The sealed battery as described. 9. The method according to claim 9, wherein the conductive member is a low melting point metal or alloy,
9. The sealed battery according to claim 7, wherein the sealed battery is a low-strength metal or alloy. 10. The conductive member is formed in a cap shape provided with a flange portion, penetrates a sealing plate, a top side of the cap shape is joined to a shutoff valve, and a flange side is joined to a sealing plate. The sealed battery according to any one of claims 7 to 9, wherein: 11. The sealed battery according to claim 1, wherein a PTC is inserted between the battery cover and the safety valve. 12. The sealed battery according to claim 1, wherein the battery is a lithium battery or a lithium ion battery.