JP2001229911A - Sealed battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sealed battery, specifically a thin secondary battery, having high safety and excellent sealing characteristics and capable of preventing bursting caused by rise in the internal pressure. SOLUTION: The sealed battery is formed by sealing a power generation element inside a battery package. On the outer surface of a small sealed package, connected to the battery package or an inner space of the battery package, a safety circuit is provided to function as a part of a charging and discharging circuit at normal times, and when the internal pressure of the battery rises, to disable charging and discharging by being broken by an expansion of the battery package.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a thin sealed battery,
In particular, the present invention relates to a sealed battery sealed by a bag-like package made of a flexible film.

[0002]

2. Description of the Related Art With the recent reduction in size and weight of various portable devices, demands for higher energy and smaller size and weight of batteries used in these devices are increasing. For example, thin secondary batteries such as polymer lithium ion secondary batteries have been rapidly developed.

[0003] With respect to the battery package in such a thin secondary battery, the trend of reduction in size and weight will be described. In the case of a thin secondary battery, when the hermeticity of the battery package is reduced, the battery performance is significantly reduced due to volatilization or leakage of the electrolyte constituting the power generation element, or intrusion of moisture from the outside. Therefore, the conventional battery package is mainly made of a metal molded product having excellent long-term reliability in a sealing function, and a change from a heavy material such as iron or stainless steel to a thin material such as aluminum has been measured. However, the metal molded product has problems in that there is a limit in weight reduction, a size is restricted by a limit of a processing technique, a molding die is expensive, and a process is complicated and cost is high. Therefore, in recent years, it has become general to further reduce the weight by using a laminated film in which a synthetic resin layer is disposed on both sides of an aluminum foil as a core material. The structure of a thin secondary battery using such a film material will be described below with reference to FIG.

FIG. 6 shows a schematic configuration of a thin secondary battery using a metal-resin composite film as a battery package. FIG.
FIG. 6A is an external perspective view, and FIG.
It is X 'sectional drawing. From the metal-resin composite film 111 formed by laminating an inner layer 112 made of a heat-fusible resin in order from the inner surface, a core layer 113 made of aluminum foil or the like, and an outer layer 114 made of a resin having rigidity such as polyethylene terephthalate. Inside the battery package 110, a thin power generation element 120 including a positive electrode 121 including a positive electrode layer 122 and a positive electrode current collector 123, a separator 124, and a negative electrode 125 including a negative electrode layer 126 and a negative electrode current collector 127 is provided. It is stored. Positive terminal 13 connected to positive current collector 123 and negative current collector 127, respectively
1 and the negative electrode terminal 132 are the metal-resin composite film 11
One of the edges 115 is exposed to the outside. Rim 115
In, the inner layer 112 made of a heat-fusible resin is heat-sealed to each other, whereby the thin power generating element 120 is sealed in the battery package 110.

In the above-described thin secondary battery, when gas is generated inside due to overcharging or the like, the internal pressure of the battery rises, and the battery package 110 made of the metal-resin composite film 111 expands to accommodate the storage portion. Pressure may cause damage to the equipment. Further, if the sealing portion is broken, flammable gas is released, which may cause a dangerous situation.

[0006] In a lithium ion battery using a battery package of a metal molded product, a charge / discharge circuit is installed on a pressure release valve provided in a battery case, and the valve is operated, and the charge / discharge circuit is cut off. By preventing the charge and discharge from proceeding, the above-described accident was prevented. But,
In a lithium ion battery using a battery package made of a metal-resin composite film, it is difficult to install such an internal pressure release valve because the battery package itself is flexible. For example, Japanese Patent Application Laid-Open No. H11-868
No. 23 and Japanese Patent Application Laid-Open No. 11-102673 disclose a method for preventing such a flexible battery package from bursting.

First, in Japanese Patent Application Laid-Open No. 11-86823, the battery package 110 shown in FIG. 6 has a structure in which the peel strength of a part of the inner layer 112 thermally fused to each other is made weaker than that of the other parts. When the battery package 110 expands due to an increase in the internal pressure, such a portion having a low peel strength is preferentially opened as a gas discharge port, so that the battery package 110 at high pressure can be prevented from bursting. It is said that.

In Japanese Patent Application Laid-Open No. 11-102673, a hole or cut is provided in a part of a battery package (metal-resin composite film), and the hole or cut is formed from the inner surface of the metal-resin composite film. Disclosed is a structure in which a metal foil is disposed so as to close the hole, and the hole or the cut portion is easily broken when the internal pressure rises and gas is released from the hole, thereby rupture of the battery package at a high pressure. Is described as being possible.

[0009]

However, the above technique has the following problems. That is, in each of the above techniques, the strength of a part of a battery package (metal-resin composite film) is intentionally weakened, and when the internal pressure rises, this part is preferentially destroyed to release gas. From the viewpoint of ensuring airtightness, it can be said that reliability is extremely poor. In other words, it has been impossible to satisfy both conflicting demands for securing strength for hermeticity and decreasing strength for gas release.

[0010] Therefore, an object of the present invention is to provide an excellent airtightness.
In addition, it is an object of the present invention to provide a highly safe sealed battery, particularly a thin secondary battery, which can prevent the battery from being over-expanded due to a rise in internal pressure and the breakage or rupture of the sealing member.

[0011]

SUMMARY OF THE INVENTION According to the present invention, a circuit for charging and discharging is cut off by detecting a package deformation caused by an increase in the internal pressure, instead of preventing a burst due to gas release when the internal pressure rises as in the prior art. The above problem is solved by providing a function that can perform the above.

That is, a sealed battery according to the present invention for solving the above-mentioned problems is a sealed battery in which a power generating element is sealed inside a battery package. It is characterized by comprising an element that makes discharging impossible. As a result, the charging / discharging circuit is shut off due to a constant increase in the internal pressure, and no further increase in the internal pressure occurs, thereby preventing overexpansion of the battery, breakage or rupture of the seal, and the like. In addition, since there is no need to break the battery package and release gas, the hermeticity of the battery package is guaranteed, and the effect of improving product reliability is obtained.

Further, the sealed battery according to the present invention is characterized in that at least one of the inner surface and the outer surface of the electric package is provided with a pressure-resistant plate in which a part of a portion in contact with the safety circuit is partially opened. Features. As a result, the battery package expands locally and preferentially at the open portion of the pressure-resistant plate, the circuit is reliably shut off, and safety is improved.

Further, the sealed battery of the present invention is characterized in that the safety circuit is arranged on the outer surface of the battery package via a brittle material. As a result, the brittle material is destroyed by a certain increase in internal pressure, and the circuit is more reliably cut off to stop charging and discharging.

Further, a sealed battery according to the present invention is characterized in that the brittle material is provided with a cut. Thereby, destruction of the flakes occurs more reliably and safety is improved.

Further, the sealed battery according to the present invention is characterized in that the cut is formed in a direction crossing the charge / discharge circuit. As a result, the flakes are more reliably destroyed, so that the circuit is more reliably cut off and safety is improved.

Further, the sealed battery according to the present invention is a sealed battery in which a power generation element is sealed inside a battery package, comprising a small sealed package which is electrically connected to the internal space of the battery package, and an outer surface of the small sealed package. And an element that detects a rise in battery internal pressure and makes charging and discharging impossible. As a result, when the internal pressure of the battery increases, the small hermetic package expands before the battery body,
Since the safety circuit is broken and charging / discharging is stopped, sensitivity to an increase in internal pressure can be increased, which contributes to improvement in safety.

The sealed battery according to the present invention is characterized in that at least one of an inner surface and an outer surface of the battery package is provided with a pressure-resistant plate. As a result, the battery package expands locally and preferentially at the open portion of the pressure-resistant plate, the circuit is reliably shut off, and safety is improved.

Further, the sealed battery according to the present invention is characterized in that at least one of the inner surface and the outer surface of the small sealed package is provided with a pressure-resistant plate in which a part of the portion in contact with the element is partially opened. Features. As a result, the battery package expands locally and preferentially at the open portion of the pressure-resistant plate, the circuit is reliably shut off, and safety is improved.

Further, the sealed battery according to the present invention is characterized in that the safety circuit is provided on the outer surface of the small sealed package via a brittle material. As a result, the brittle material is destroyed by a certain increase in internal pressure, and the circuit is more reliably cut off to stop charging and discharging.

Further, the sealed battery according to the present invention is characterized in that the thin section is provided with a cut. Thereby, destruction of the flakes occurs more reliably and safety is improved.

The sealed battery according to the present invention is characterized in that the cut is formed in a direction crossing a direction in which a current flows through the element. This more reliably breaks the flakes, so the safety circuit is more reliably interrupted,
Safety is improved.

[0023]

(Embodiment 1) A first embodiment of the present invention will be described below. 1A and 1B show an example of a sealed battery of the present invention. FIG. 1A is an external perspective view, and FIG.
It is sectional drawing in X '. In the sealed battery 100, a positive electrode layer 122 and a positive electrode current collector 123 are provided inside a battery package 110 including a metal-resin composite film 111 formed by laminating an inner layer 112, a core layer 113, and an outer layer 114. And a negative electrode 12 including a negative electrode layer 126 and a negative electrode current collector 127.
5 are housed. The positive electrode terminal 131 and the negative electrode terminal 132 connected to the positive electrode current collector 123 and the negative electrode current collector 127 are exposed to the outside from the edge 115 of the metal-resin composite film 111. At the edge 115, the inner layers 112 are in close contact with each other, whereby the thin power generating element 120 is sealed in the battery package 110.

A specific example of the configuration of the metal-resin composite film 111 is as follows.
Using a heat-fusible resin of about 00 μm, for example, an acid-modified polypropylene or an acid-modified polyethylene, and heat-sealing the resin ensures the tightness of the battery. Core layer 1
As 13, an aluminum foil having a thickness of about 20 to 100 μm is used. As the outer layer 114, a resin having a thickness of about 10 to 30 μm and having rigidity, for example, polyethylene terephthalate, polyamide, or polyimide is preferably used.

A conductive wire 133 is bonded and fixed to the outer surface of the metal-resin composite film 111, and the negative terminal 132 and the conductive wire 133 are connected to form a part of a charge / discharge circuit. The conducting wire 133 is a metal foil made of silver, copper, aluminum, or the like, and its thickness and width are appropriately determined according to the magnitude of the current flowing. For example, in the case of a small battery having a capacity of 500 to 1000 Ah, a thickness of 30 to 200 μm and a width of 0.5 to 3
mm is appropriate.

In the overcharged or overdischarged state, if the battery package 110 of the sealed battery 100 slightly swells and deforms, the wire 133 is broken by a tension and a bending force. The lead 133 is connected to the negative terminal 13 as described above.
2, the charging / discharging circuit is configured to be part of the charging / discharging circuit. Therefore, when the charging / discharging circuit is broken, charging / discharging of the sealed battery 100 is stopped, and no more gas is generated inside. Therefore, it is possible to prevent the battery from being over-expanded, the seal from being broken or ruptured, and the like. Note that, in the present embodiment, an example in which the conductive wire 133 is connected to the negative electrode terminal 132 is shown, but the effect is the same even if the conductive wire 133 is connected to the positive electrode terminal 131.

(Embodiment 2) A second embodiment of the present invention will be described below. The description of the same parts as those in the first embodiment will be omitted, and only different parts will be described. FIG. 2 is an example of the sealed battery of the present invention,
(A) is an external perspective view, (b) is a cross-sectional view taken along line XX 'of (a). In the present embodiment, a pressure-resistant plate 210 that covers the battery package 110 and has a hole 211 at one position in a portion that comes into contact with the conductive wire 133 is provided. With such a configuration, when the battery package 110 is deformed, the deformation is concentrated on the hole 211 and a small radius of curvature is generated.
The tension and bending force applied to 3 increase. Therefore, the conductive wire 133 can be cut with high sensitivity to minute deformation. That is, overexpansion of the battery, destruction or rupture of the seal, and the like can be more reliably prevented.

In FIG. 2, the shape of the hole 211 is square, but the shape is not limited to this.
In this portion, it can be arbitrarily determined so that the deformation of the battery package 110 is concentrated.

Although the pressure-resistant plate 210 is provided on the outer surface of the battery package 110 in this embodiment, the same effect can be obtained by providing the same on the inner surface of the battery package 110. Alternatively, it may be provided on both the outer surface and the inner surface of the battery package 110. Further, the pressure plate 210 is not a separate component, and a member constituting a wall of the battery storage space of the device can also serve as the pressure plate 210.

Embodiment 3 Next, a third embodiment of the present invention will be described below. The description of the same parts as those in the first embodiment will be omitted, and only different parts will be described. 3A and 3B show an example of the sealed battery of the present invention, in which FIG. 3A is an external perspective view, and FIG. 3B is a cross-sectional view taken along line XX ′ of FIG. In the first embodiment, the conductive wire 133 is directly adhered to the outer surface of the metal-resin composite film 111, but in the present embodiment, the flakes 3 made of a brittle material are formed on the outer surface of the metal-resin composite film 111.
10 and the conductive wire 133 is provided on the upper surface of the thin piece 310 by bonding or printing. Slice 310
For example, ceramics or thermosetting resin is appropriate,
The thickness is desirably 0.1 to 0.2 mm.

In the state of overcharge or overdischarge,
Tensile force and bending force are applied to 10 to break it. At this time, since the thin piece 310 is formed of the brittle material as described above, the thin piece is easily broken by a slight expansion of the battery as compared with the first embodiment. That is, the conductive wire 133 formed on the upper surface of the thin piece 310 is also more reliably and easily broken as compared with the first embodiment. Therefore, the sensitivity to the expansion of the battery is high, and the overexpansion of the battery, the destruction or rupture of the seal, and the like can be more reliably prevented.

At this time, it is effective to provide a cut in the slice 310 to further increase the sensitivity. In particular, if the cuts 410 are provided in the direction intersecting with the conductor 133 as shown in FIG. 4, stress concentration occurs in the cuts 410 in the thin piece 310, and the thin pieces 310 are easily broken.

(Embodiment 4) Next, a fourth embodiment of the present invention will be described below. The description of the same parts as those in the first embodiment will be omitted, and only different parts will be described. FIG. 5 is an external perspective view showing an example of the sealed battery of the present invention. In the present embodiment, the battery package 1
10, a small airtight package 510 that communicates with the inside of the small airtight package 10 is disposed.
Are bonded. The small hermetic package 510 is made of a material having a small thickness and / or a stretchable material such as polypropylene or polyethylene so that it expands more easily than the metal-resin composite film 111 constituting the battery package 110. With such a configuration, when the internal pressure of the battery increases, the small hermetic package 510 expands prior to the battery package 110, and the conductive wire 133 is broken. Therefore, the conductive wire 113 can be broken with high sensitivity to an increase in the internal pressure of the battery, and it is possible to more reliably prevent the battery from being over-expanded, the seal from being broken or ruptured, and the like.

Embodiment 5 Next, a fifth embodiment of the present invention will be described below. In the present embodiment, the pressure-resistant plate 210 used in the second embodiment is applied to the sealed battery 100 shown in the fourth embodiment. However, in the present embodiment, the hole 211 is not provided in the pressure-resistant plate 210. With such a configuration, the same effect can be obtained even when the battery package 110 is the same as the battery package 110 without adjusting the thickness and the constituent material of the small sealed package 510 as in the fourth embodiment.

The pressure-resistant plate 210 is connected to the battery package 110.
Is provided on the outer surface of the battery package 110, but the same effect can be obtained even when provided on the inner surface of the battery package 110, as in the second embodiment. Alternatively, it may be provided on both the outer surface and the inner surface of the battery package 110. Further, the pressure plate 210 is not a separate component, and a member constituting a wall of the battery storage space of the device can also serve as the pressure plate 210.

Next, a sixth embodiment of the present invention will be described below. In the present embodiment, a pressure-resistant plate is further provided for the small hermetic package 510 in the fifth embodiment. In other words, a pressure-resistant plate that covers the surface of the small hermetic package 510 and has a hole at one location in a portion that comes into contact with the conductive wire 133 is provided. With such a configuration, when the small hermetic package 510 is deformed, the deformation is concentrated on the hole portion and a small radius of curvature is generated, so that the tension and bending force applied to the conductive wire 133 are increased. Therefore, the conductive wire 13 is highly sensitive to smaller deformation.
3 can be cut. That is, overexpansion of the battery, breakage or rupture of the seal, and the like can be more reliably prevented.

The shape of the hole is arbitrarily determined, such as a circle, as in the second embodiment. Although the pressure-resistant plate is provided on the outer surface of the small sealed package 510, the same effect can be obtained by providing the same on the inner surface of the small sealed battery package 510 as in the second embodiment. Small sealed package 510
May be provided on both the outer surface and the inner surface.

(Embodiment 7) Next, a seventh embodiment of the present invention will be described below. In the present embodiment, the thin piece 310 used in the third embodiment is applied to the small hermetic package 510 shown in the fourth embodiment. That is, a thin piece 310 made of a brittle material is provided on the outer surface of the small hermetic package 510, and the conductive wire 130 is provided on the upper surface of the thin piece 310. With such a configuration, in a state of overcharging or overdischarging, the thin piece 310 is broken by applying tension and bending force. At this time, since the thin piece 310 is formed of the brittle material as described above, the thin piece is easily broken by a slight expansion of the battery as compared with the fourth embodiment. That is, the flake 310
The conductive wire 133 formed on the upper surface is also more reliably and easily broken as compared with the first embodiment. Therefore, the battery has high sensitivity to the expansion of the battery, and it is possible to more reliably prevent the battery from being over-expanded, the seal from being broken or ruptured, and the like.

At this time, it is effective to provide a cut in order to further increase the sensitivity. In particular, as shown in FIG. 4, it is effective to provide the cuts 410 in a direction intersecting with the conductor 133 as described in the third embodiment.

This embodiment is also applied to the sealed battery 100 in which the battery package 110 shown in the fifth embodiment is provided with the pressure-resistant plate 210.

[0041]

As described above, according to the present invention, it is possible to obtain a sealed battery having high sealing reliability and high safety against overcharge and overdischarge.

[Brief description of the drawings]

FIG. 1 is an external perspective view and a sectional view showing a first embodiment of a sealed battery according to the present invention.

FIG. 2 is an external perspective view and a sectional view showing a second embodiment of the sealed battery of the present invention.

FIG. 3 is an external perspective view showing a third embodiment of the sealed battery of the present invention.

FIG. 4 is a schematic configuration diagram for explaining the structure of a thin section.

FIG. 5 is an external perspective view showing a fourth embodiment of the sealed battery according to the present invention.

FIG. 6 is an external perspective view and a cross-sectional view showing the structure of a conventional sealed battery.

[Explanation of symbols]

 REFERENCE SIGNS LIST 100 sealed battery 110 battery package 111 metal-resin composite film 112 inner layer 113 core layer 114 outer layer 115 edge 120 thin power generating element 121 positive electrode 122 positive electrode layer 123 positive electrode current collector 124 separator 125 negative electrode 126 negative electrode layer 127 negative electrode current collector 131 Positive terminal 132 Negative terminal 133 Conductor 210 Pressure plate 211 Hole 310 Thin piece 410 Cut 510 Small sealed package

Claims (11)

[Claims] In a sealed battery in which a power generation element is sealed inside a battery package, the outer surface of the battery package normally functions as a part of a charge / discharge circuit, and senses a rise in battery internal pressure to charge / discharge. A sealed battery comprising an element that is made impossible. 2. The battery package according to claim 1, wherein at least one of an inner surface and an outer surface of the battery package is provided with a pressure-resistant plate in which a part of the portion in contact with the element is partially opened. Sealed battery. 3. The sealed battery according to claim 1, wherein the safety circuit is disposed on an outer surface of the battery package via a brittle material. 4. The sealed battery according to claim 3, wherein the brittle material has a cut. 5. The sealed battery according to claim 4, wherein the cut is formed in a direction crossing a direction in which a current flows through the element. 6. A sealed battery in which a power generating element is sealed inside a battery package, comprising a small sealed package that is electrically connected to an internal space of the battery package, and detecting an increase in battery internal pressure on an outer surface of the small sealed package. A sealed battery comprising an element that makes charging and discharging impossible. 7. The sealed battery according to claim 6, wherein a pressure plate is provided on at least one of an inner surface and an outer surface of the battery package. 8. A pressure-resistant plate in which at least one of an inner surface and an outer surface of the small hermetic package is provided with a pressure-resistant plate in which a part of a portion abutting on the safety circuit is partially opened. A sealed battery according to claim 1. 9. The sealed battery according to claim 6, wherein the safety circuit is disposed on the outer surface of the small sealed package via a brittle material. 10. The sealed battery according to claim 9, wherein a cut is made in the flake made of the brittle material. 11. The sealed battery according to claim 10, wherein the cut is formed in a direction crossing a safety circuit.