JP2003338315A - Battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a battery capable of reliably preventing thermorunaway reaction from being caused even when a battery temperature rises due to excessive charging. <P>SOLUTION: In this battery provided with a group of electrodes 1 which are formed by winding a positive electrode 2 and a negative electrode 3 through a separator 4, an exterior case 7 storing the group of electrodes 1 in its inside and serving as one electrode terminal, and a sealing member 9 disposed at the opening part of the exterior case 7 through an insulating material 10 while serving as the other electrode terminal, a resin layer 8 fusible at low temperatures, which fuses at lower temperatures than the fusing temperature of the separator 4, or at lower temperatures than the interrupting temperature of the separator 4 if it has a current interrupting function, is interposed between the negative electrode 3 on the extreme circumference of the group of electrodes 1 and the surface facing the exterior case 7 having reverse polarity. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a battery in which a positive electrode plate and a negative electrode plate are wound with a separator interposed between them, and an electrode plate group is housed in an outer case and sealed with a sealing member.

[0002]

2. Description of the Related Art In recent years, electronic devices have been rapidly reduced in size and weight, and the size of a battery used as a power source has been reduced.
The demand for lighter weight and higher capacity is increasing.

The structure of a conventional battery of this type is shown in FIG.
Will be described with reference to. Reference numeral 21 denotes an electrode plate group, which is formed by spirally winding a positive electrode plate 22 and a negative electrode plate 23 with a separator 24 in between. Reference numerals 25 and 26 denote a positive electrode current collector plate and a negative electrode current collector plate joined to both end faces of the electrode plate group 21, and a negative electrode tab 26a is welded to the negative electrode current collector plate 26.

The electrode plate group 21 is housed in an outer case 27, and the positive electrode current collector plate 25 is resistance-welded to the inner bottom surface of the outer case 27 so that the outer case 27 serves as a positive electrode terminal of the battery.
In addition, the electrolyte solution is injected into the outer case 27, and
1 is impregnated.

Reference numeral 28 is a sealing member, and an explosion-proof valve body 3 is provided on a saucer-shaped sealing plate 29 having an opening at the center through an O-ring 30.
1 is arranged, and a spacer 32 having an opening in the center thereof
A cap 33 having a gas discharge port formed thereon is covered with the sealing plate 29 and the outer peripheral portion of the sealing plate 29 is caulked to be integrated. The explosion-proof valve body 31 is made of a thin film aluminum foil, and is configured to break when the internal pressure of the battery rises above a predetermined pressure and discharge the gas inside the battery to the outside.

The negative electrode tab 26a is welded to the sealing member 28, and the cap 33 becomes the negative electrode terminal of the battery. The outer case 27 is sealed by inserting the gasket 34 around the outer periphery of the sealing member 28 into the opening of the outer case 27 and caulking the opening of the outer case 27 with the gasket 34 interposed. Has been done. Gasket 3
4 has a function of insulating the outer case 27 of the positive electrode terminal and the sealing member 28 of the negative electrode terminal.

Further, in JP-A-11-176478 and JP-A-2000-36324, as a means for improving the safety in the nail penetration test, a group of electrode plates contacting the inner circumference of the outer case serving as a negative electrode terminal is disclosed. The outermost peripheral portion of the negative electrode plate of, and the outermost peripheral portion of the positive electrode plate of the inside of the negative electrode plate only the current collector core, by placing a separator between them, also, the outermost positive electrode plate or negative electrode plate By using only the current collector core and inserting a separator between the negative electrode terminal and the outer case that will be the positive electrode terminal, the short-circuit current is dispersed during nail penetration and the heat generation density is reduced. Is disclosed in which the heat dissipation is improved only by using a metal collector core made of metal to lower the local temperature and prevent thermal runaway.

[0008]

By the way, in the battery having the structure shown in FIG. 3, when the battery is overcharged, an exothermic reaction occurs and the battery temperature rises. There is a problem that the active material is thermally decomposed to generate gas, which may cause a thermal runaway reaction of the battery.

On the other hand, in the means disclosed in the above-mentioned JP-A Nos. 11-176478 and 2000-36324, short-circuit current concentrates locally at the time of nail sticking, the heat generation density becomes high, and thermal runaway reaction occurs. Although it is possible to prevent the occurrence of such a situation, it is not possible to achieve the effect of suppressing heat generation due to overcharge.

In view of the above conventional problems, it is an object of the present invention to provide a battery capable of reliably preventing the occurrence of a thermal runaway reaction even when the battery temperature rises due to overcharging.

[0011]

The battery of the present invention comprises an electrode plate group in which a positive electrode plate and a negative electrode plate are wound with a separator interposed therebetween, and an outer case which houses the electrode plate group and serves as one electrode terminal. And a sealing member which is disposed in the opening of the outer case via an insulating member and serves as the other electrode terminal. (1) The outermost electrode plate of the electrode plate group and the outer case having a polarity opposite to that of the outermost electrode plate. A low temperature melting resin layer that melts at a temperature lower than the melting temperature of the separator is interposed between the surfaces, or (2) between the facing surfaces of the outermost electrode plate of the electrode plate group and the outer case having the opposite polarity,
Interposing a low-temperature molten resin layer that melts at a temperature lower than the cutoff temperature of the separator having a current cutoff function, or (3)
A low temperature molten resin layer that melts at a temperature lower than the melting temperature of the separator is interposed between the facing surfaces of the innermost electrode plate of the electrode plate group and the member connected to the outer case having the opposite polarity, or ( 4) Low-temperature melting that melts at a temperature lower than the cutoff temperature of the separator having a current cutoff function between the facing surfaces of the innermost polar plate of the electrode plate group and the member connected to the outer case having the opposite polarity. A resin layer is interposed.

According to the above construction, when the battery temperature rises due to overcharging and becomes higher than the melting temperature of the low temperature melting resin, the low temperature melting resin layer is melted and the polar plate of the polar plate group and the polar plate opposite thereto are melted. Battery energy is dissipated before the thermal runaway reaction of the battery occurs due to the short circuit between the outer case or the member connected to the outer case and the short circuit current flows.Even when the nail is stabbed, heat is generated by the short circuit current, making it easy. It is possible to prevent a situation in which the outer case and the electrode plate inside the outer case are short-circuited, the heat generation density is reduced, and a thermal runaway reaction occurs.

Further, it is preferable that the active material is also applied to the portion of the electrode plate which is in contact with the low temperature melting resin layer, because the short circuit current at the time of melting the low temperature melting resin layer can be prevented from becoming excessive.

The low temperature melting resin layer is the melting temperature of a general separator made of polyethylene resin or the like 18
80 ° C. to 10 ° C. lower than about 0 ° C. and 120 ° C. to 130 ° C. at which the micropores of the microporous polyethylene film are clogged and the current blocking function is exhibited.
It is preferably composed of a low molecular weight polyethylene resin that melts at 0 ° C.

Further, the low temperature melting resin layer is preferably composed of a resin film provided on the outer circumference or inner circumference of the electrode plate group, and is connected to the inner circumference of the outer case or the central portion of the outer case. It may be configured by a resin coating layer applied to the outer periphery of the member.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment in which the battery of the present invention is applied to a lithium ion battery will be described below with reference to FIG.

In FIG. 1 showing the structure of the battery of this embodiment, reference numeral 1 denotes an electrode plate group, which is basically the same as that described in the conventional example, and has a strip-shaped positive electrode plate 2 and negative electrode plate 3 between them. And a negative electrode plate 3 arranged on the outermost periphery thereof. The positive electrode plate 2 is L
A positive electrode mixture containing a positive electrode active material such as iCoO _{2 is applied to} a collector core material 2a such as an aluminum foil to form a negative electrode plate 3
Is formed by applying a negative electrode mixture containing a negative electrode active material such as a carbon material that absorbs and desorbs lithium ions to a collector core material 3a such as copper foil, and the separator 4 is formed of a microporous polyethylene film. There is.

A positive electrode current collector plate 5 and a negative electrode current collector plate 6 are disposed on the lower end surface and the upper end surface of the electrode plate group 1, respectively, and collector electrodes 2a and 3a of respective polarities are welded and joined. A negative electrode tab 6 a is welded to the negative electrode current collector plate 6.

The electrode plate group 1 is housed in the outer case 7, and between the outer circumference of the electrode plate group 1 and the inner circumference of the outer case 7 is made of insulating low molecular weight polyethylene.
80 ° C. to 100 ° C., which is lower than 120 ° C. to 130 ° C., in which the fine holes of the separator 4 are clogged to cut off the current
A low temperature melting resin layer 8 that melts at a temperature of about 3 is interposed. It is preferable that the low-temperature melting resin layer 8 is composed of a low-temperature melting resin film wound around the outermost negative electrode plate 3 of the electrode plate group 1 in terms of manufacturing cost. You may comprise by the resin coating layer formed in the surface.

With the electrode group 1 housed in the outer case 7, the positive electrode current collector plate 5 is welded and joined to the bottom surface of the outer case 7, and the negative electrode current collector plate 6 is attached to the sealing member 9 via the negative electrode tab 6a. After welding and joining, the electrolytic solution is injected, and the opening of the outer case 7 is sealed by the sealing member 9. That is, the sealing member 9 has basically the same configuration as the sealing member 28 of the above-described conventional example, and has a safety valve (not shown) built therein, and the sealing member 9 closes the opening of the outer case 7. It is fitted and arranged via a gasket 10, and the opening end of the outer case 7 is caulked to be sealed by the sealing member 9.

According to the battery having the above structure, the battery temperature rises due to overcharge, and the melting temperature of the low temperature molten resin is 8
When the temperature becomes higher than 0 ° C. to 100 ° C., the low temperature molten resin layer 8 melts, the negative electrode plate 3 at the outermost periphery of the electrode plate group 1 and the outer case 7 having the opposite polarity to each other are short-circuited, and a short-circuit current flows. Since the battery energy is dissipated, it is possible to prevent the thermal runaway reaction of the battery from occurring.

Also, when the nail is stabbed, the outer case 7 and the negative electrode plate 3 inside the outer case 7 are easily short-circuited due to the heat generated by the short-circuit energization.
It is possible to prevent the occurrence of a situation in which the heat generation density decreases and a thermal runaway reaction occurs.

Further, the negative electrode mixture is applied to the outermost negative electrode plate 3 of the electrode plate group 1 and short-circuited via the mixture layer having a relatively large current resistance, so that the current collecting core material 3a is directly connected. Exterior case 7
A large current does not flow as in the case where the battery contacts with and short-circuits, and the battery energy can be dissipated in a state where the temperature rise rate is controlled.

In the above embodiment, the outermost periphery of the electrode plate group 1 is the negative electrode plate 3 and the outer case 7 is the positive electrode. However, conversely, the outermost periphery of the electrode plate group 1 is the positive electrode plate 2. Needless to say, the outer case 7 may be used as the negative electrode.

Next, another embodiment of the battery of the present invention will be described with reference to FIG. In the above embodiment, an example in which the low temperature melting resin layer 8 is interposed between the outermost periphery of the electrode plate group 1 and the inner periphery of the outer case 7 having a polarity opposite to that of the electrode plate group 1 is shown. A metal winding core 11 is arranged at the center of 1, and a low temperature melting resin layer 8 is arranged on the outer periphery thereof. The low temperature melting resin layer 8 may be formed by winding a low temperature melting resin film around the outer circumference of the winding core 11 or may be formed of a resin coating layer.

On the outer circumference of the winding core 11, the negative electrode plate 3 is formed on the innermost circumference.
Is arranged, and the electrode plate group 1 is wound so that the separator 4 is arranged outside the outermost peripheral negative electrode plate 3. Winding core 1
One end of 1 and the collector core material 2a of the positive electrode plate 2 are welded to the positive electrode collector plate 5, and the collector core material 3a of the negative electrode plate 3 is the negative electrode collector plate 6.
It is welded to. The electrode plate group 1 is housed in the outer case 7, the positive electrode current collector plate 5 is welded and joined to the bottom surface of the outer case 7, and the negative electrode current collector plate 6 is sealed via the negative electrode tab 6a.
Welded and joined to.

Also in this embodiment, as in the above embodiment, the battery temperature rises due to overcharging and the temperature rises from 80.degree.
When the temperature becomes higher than 0 ° C., the low-temperature melting resin layer 8 melts, and the innermost negative electrode plate 3 of the electrode plate group 1 has the winding core 11, the positive electrode current collector plate 5, and the outer case 7 of the opposite polarity. Since a short circuit occurs and a short circuit current flows and the battery energy is dissipated, it is possible to prevent the thermal runaway reaction of the battery from occurring. In addition,
It goes without saying that the polarities may be reversed.

In the above embodiment, as a suitable example, the melting temperature of the low temperature melting resin layer 8 is 80 ° C to 100 ° C.
However, the temperature is lower than about 180 ° C which is the melting temperature of a general separator made of polyethylene resin, etc., and the micropores of the microporous polyethylene film are clogged to exhibit the current blocking function. In the case of a used separator, its current interruption temperature is 120 ° C to 130 ° C.
It may be set to a temperature lower than the above temperature and to a temperature high enough not to melt under the most severe temperature conditions under normal use.

In the above embodiment, low-molecular-weight polyethylene is shown as an example of the low-temperature melting resin layer, but low-molecular-weight polypropylene, polyisobutylene, polyethylene oxide, polypropylene oxide and the like can be suitably applied. .

[0030]

EFFECTS OF THE INVENTION According to the battery of the present invention, as described above, the outermost or innermost electrode plate of the electrode plate group and the opposite surface of the outer case or the member connected to the outer case having the opposite polarity. In the meantime, since a low-temperature molten resin layer that melts at a temperature lower than the melting temperature of the separator or when the separator has a current cutoff function is melted at a temperature lower than the cutoff temperature, the battery temperature rises due to overcharge, When the temperature is higher than the melting temperature of the low-temperature molten resin, the low-temperature molten resin layer melts and the electrode plates of the electrode group and the outer case of the opposite polarity or a member connected to the outer case short-circuit and a short-circuit current flows. , The battery energy is dissipated before the thermal runaway reaction of the battery occurs, and when the nail is stabbed, the heat generated by the short circuit current easily short-circuits the outer case and the inner electrode plate, and the heat density decreases. You It is the generation of thermal runaway reaction is reliably prevented can provide a highly safe battery.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of an embodiment of a battery of the present invention.

FIG. 2 is a vertical cross-sectional view of another embodiment of the battery of the present invention.

FIG. 3 is a vertical cross-sectional view of a conventional battery.

[Explanation of symbols]

1 plate group 2 Positive plate 3 Negative electrode plate 4 separator 7 Exterior case 8 Low temperature resin layer 9 Sealing member 11 winding core

Continued front page    (72) Inventor Tetsuya Niimoto             1006 Kadoma, Kadoma-shi, Osaka Matsushita Electric             Sangyo Co., Ltd. (72) Inventor Yasutaka Furui             1006 Kadoma, Kadoma-shi, Osaka Matsushita Electric             Sangyo Co., Ltd. (72) Inventor Takeshi Hatanaka             1006 Kadoma, Kadoma-shi, Osaka Matsushita Electric             Sangyo Co., Ltd. F term (reference) 5H021 CC17 EE02 HH06 HH10                 5H028 AA05 AA08 CC12 EE06 HH08                 5H029 AJ12 AK03 AL06 BJ02 BJ14                       BJ27 DJ04 EJ12 HJ12 HJ14

Claims (8)

[Claims] 1. An electrode group in which a positive electrode plate and a negative electrode plate are wound with a separator interposed therebetween, an outer case that houses the electrode plate group and serves as one electrode terminal, and an insulating member in an opening of the outer case. And a sealing member that serves as the other electrode terminal, and is melted at a temperature lower than the melting temperature of the separator between the facing surfaces of the outermost electrode plate of the electrode plate group and the outer case having the opposite polarity. A battery having a low temperature melting resin layer interposed therebetween. 2. An electrode plate group in which a positive electrode plate and a negative electrode plate are wound with a separator interposed therebetween, an outer case that houses the electrode plate group and serves as one electrode terminal, and an insulating member in an opening of the outer case. And a sealing member serving as the other electrode terminal, and between the facing surfaces of the outermost electrode plate of the electrode plate group and the outer case having the opposite polarity, the cutoff temperature of the separator having a current cutoff function. A battery in which a low-temperature melting resin layer that melts at a lower temperature is interposed. 3. An electrode plate group in which a positive electrode plate and a negative electrode plate are wound via a separator, an outer case that houses the electrode plate group and serves as one electrode terminal, and an insulating member in an opening of the outer case. And a sealing member serving as the other electrode terminal, and the innermost electrode plate of the electrode plate group, and between the opposing surfaces of the member connected to the outer case of the opposite polarity, the separator of A battery in which a low-temperature melting resin layer that melts at a temperature lower than the melting temperature is interposed. 4. An electrode plate group in which a positive electrode plate and a negative electrode plate are wound via a separator, an outer case that houses the electrode plate group and serves as one electrode terminal, and an insulating member in an opening of the outer case. And a sealing member serving as the other electrode terminal disposed between the electrode plate and the opposite surface of the innermost electrode plate of the electrode plate group and the member connected to the outer case having the opposite polarity to cut off current. A battery in which a low-temperature melting resin layer that melts at a temperature lower than the cut-off temperature of a functional separator is interposed. 5. The battery according to any one of claims 1 to 4, wherein the active material is also applied to a portion of the electrode plate which is in contact with the low temperature melting resin layer. 6. The battery according to claim 1, wherein the low-temperature melting resin layer is made of a resin that melts at a temperature of 80 ° C. to 100 ° C. 7. The battery according to claim 1, wherein the low-temperature melting resin layer comprises a resin film provided on the outer circumference or the inner circumference of the electrode plate group. 8. The battery according to claim 1, wherein the low-temperature melting resin layer is a resin coating layer applied to the inner circumference of the outer case or the outer circumference of a member connected to the center of the outer case. .