JPH11167909A - Explosion-proof valve device for nonaqueous electrolyte battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an explosion proof valve device capable of accurately exhausting gas, when the internal pressure in a battery is increased by the misuse of the battery or an accidental state, increasing electrolyte leakage resistance, as well as enhancing safety and reliability. SOLUTION: An explosion-proof valve device has a sealing plate 2 for sealing the opening part of a case 1 and having an explosion-proof valve hole 4 sealed with a resin film 2b, a rivet 5 inserted into the central part of the sealing plate 2 and also serving as a terminal, a resin upper insulating gasket 6 for insulating the sealing plate 2 from the rivet 5, and a metallic washer 7 for electrically connecting the rivet 5 and a lead plate having the same polarity of an electrode group 11 via a lower insulating gasket 8 of the rivet 5.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a thin nonaqueous electrolyte battery, and more particularly to an explosion-proof valve device for a sealing plate thereof.

[0002]

2. Description of the Related Art In recent years, as communication devices, AV devices, and personal computers have become cordless and portable, there is an increasing demand for batteries that are driving power sources to be small, light, and have high energy density. In particular, a lithium secondary battery is a battery having a high energy density, is expected as a next-generation main battery, and has a large potential market scale. Further, as for the shape, there is an increasing demand for a prismatic battery from the viewpoint of making the device thinner or effectively utilizing the space of the device.

[0003] However, in a lithium secondary battery, gas is generated in the battery due to misuse of the battery such as short circuit, overcharge, reverse charge, or the like, or decomposition of an electrolyte or an active material in an abnormal situation. Rapid rise could cause rupture or fire.

[0004] In order to prevent such a sudden increase in the internal pressure of the battery, an explosion-proof valve which is deformed with an increase in the internal pressure is provided as shown in JP-A-2-112151. An explosion-proof valve device is known in which an explosion-proof valve breaks when a value reaches a predetermined value and releases gas accumulated in the battery to the outside of the battery.

[0005]

However, a battery provided with the above explosion-proof valve device has a complicated current cut-off mechanism or an explosion-proof structure. It was necessary to provide a process, and it was difficult to obtain a highly reliable explosion-proof valve device.

An object of the present invention is to provide an explosion-proof valve device having higher reliability than the conventional example.

[0007]

According to the present invention, there is provided a case for accommodating an electrode group and an electrolyte therein, a sealing plate having an explosion-proof valve for closing an opening of the case, and A rivet also serving as an arranged terminal, an upper insulating gasket made of resin for insulating the sealing plate and the rivet, and a lower part of the rivet having a lead plate having the same polarity as the rivet via a lower insulating gasket made of resin. The sealing plate is provided with a hole for an explosion-proof valve in a cover plate, and a lower portion of the hole for the explosion-proof valve is covered with a polypropylene resin film. It is configured.

As a result, the polypropylene resin film of the explosion-proof valve provided on the sealing plate is broken due to erroneous use of the battery such as short-circuit, overcharge, reverse charge, etc., and an increase in the internal pressure of the battery in an abnormal situation. By discharging the gas, it is possible to effectively prevent a sharp rise in the temperature of the battery and a rise in the internal pressure of the battery. In addition, as the material of the resin film that is the explosion-proof valve, one selected from polyethylene terephthalate resin, perfluoroalkoxy fluororesin, and polysulfone resin in addition to polypropylene is preferable.

The thickness of the resin film is 10 to 100 μm.
Is preferable, and the pressure at which the resin film breaks is 2 to 15 kg.
By setting it to f / cm ² , it is possible to more effectively prevent a sharp rise in the temperature of the battery and a rise in the internal pressure of the battery.

The upper surface of the explosion-proof valve hole may be deformed so as to have a needle-like projection projecting toward the center of the explosion-proof valve hole on the upper surface of the explosion-proof valve hole. When a metal plate having a needle-like projection is welded in the lower surface direction, a more stable pressure at which the resin film is broken can be obtained.

Further, the explosion-proof valve of the sealing plate has a structure in which an aluminum foil is welded to a lower portion of an explosion-proof valve hole provided in a cover plate, or an aluminum foil is welded to the entire lower surface of the cover plate. As a result, the aluminum foil of the explosion-proof valve provided on the sealing plate breaks due to misuse of the battery such as short-circuit, overcharge, reverse charge, etc., and an increase in the internal pressure of the battery in an abnormal situation, thereby discharging gas from the battery. This makes it possible to effectively prevent a sudden increase in the temperature of the battery and an increase in the internal pressure of the battery. At this time, the aluminum foil is 10 to 40 μm.
By setting the pressure at which the aluminum foil ruptures to ² to 15 kgf / cm ² , it is possible to more effectively prevent a sudden increase in the temperature of the battery and an increase in the internal pressure of the battery.

Further, the upper surface of the explosion-proof valve hole is deformed so as to have a needle-like projection projecting toward the center of the explosion-proof valve hole, or the explosion-proof valve hole is formed. When a metal plate having needle-like projections is welded in the lower surface direction, a more stable pressure for breaking the resin film can be obtained.

The upper insulating gasket and the lower insulating gasket of the sealing plate are selected from polyethylene terephthalate resin, perfluoroalkoxy fluororesin, polysulfone resin, and polyphenylene sulfide resin which are excellent in heat resistance and electrolytic solution resistance. In the case of molding with different types of materials, a sealing plate with excellent liquid leakage resistance and high reliability can be obtained by combining them. If the lower insulating gasket is bent in the direction of the electrode group so as to surround the metal washer that electrically connects the lead plate of the electrode group, contact between the washer and the electrode group And a highly safe battery can be obtained.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION In the explosion-proof valve device for a non-aqueous electrolyte battery according to the present invention, a case for accommodating an electrode plate group and an electrolyte therein;
Sealing the opening of the case, a sealing plate in which a resin film is welded to the explosion-proof valve hole, a rivet also serving as a terminal inserted in the center of the sealing plate, and an upper insulating gasket that insulates the sealing plate from the rivet. It has a metal washer that electrically connects the rivet and the lead plate of the same polarity of the electrode group via the lower insulating gasket of the rivet, and the case and the sealing plate can be welded by laser welding. , A sealing plate with a liquid injection port, a sealing plate with a concave rim, a circular explosion-proof valve hole, a center of the explosion-proof valve hole on the top surface of the explosion-proof valve hole The explosion-proof valve hole upper surface is deformed so as to have a needle-like protrusion projecting in the direction, or the explosion-proof valve hole has an acicular protrusion in the lower surface direction of the explosion-proof valve hole on the upper surface. Welded metal plate, sealing plate lid plate The entire lower surface of the lower or the cover plate of the explosion-proof valve hole portion may be an embodiment that the aluminum foil is welded by ultrasonic welding or covered with aluminum foil.

[0015]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is an example of a sectional view of a battery equipped with an explosion-proof valve device for a non-aqueous electrolyte battery according to the present invention. 1 is a square case made of aluminum. Reference numeral 2 denotes a sealing plate, and an explosion-proof valve 3 is provided on a flat cover plate 2a made of aluminum. The lower surface of the explosion-proof valve hole 4 of the cover plate 2a of the explosion-proof valve 3 is covered with a resin film 2b made of polypropylene. The sealing plate 2 is laser-welded to the square case 1.
Numeral 5 is a nickel-plated iron terminal.
Is a rivet disposed at the center of the rim, 6 is an upper insulating gasket for insulating the sealing plate 2 and the rivet 5, 7 is a nickel-plated iron washer, and 8 is a lower insulating gasket for insulating the sealing plate 2 and the washer 7. is there. The rivet 5 is provided at the center opening of the sealing plate 2 with an upper insulating gasket 6.
After the washer 7 is disposed below the rivet 5 via the lower insulating gasket 8, the rivet 5
By caulking, the rivet 5 and the washer 7 are electrically connected, and the insulation from the cover plate 2a is also ensured. Reference numeral 9 denotes an injection port opened in the cover plate 2a, and reference numeral 10 denotes a stopper for closing the injection port 9. Reference numeral 11 denotes a group of electrode plates obtained by winding a positive electrode plate and a negative electrode plate through a separator and pressing them into an oval shape. Reference numeral 12 denotes an aluminum positive electrode current collecting lead taken out of the positive electrode plate and welded to the cover plate 2a. Also, 13
Is a nickel negative electrode current collecting lead taken out of the negative electrode plate and welded to the washer 7. Therefore, as a battery, the case 1 is a positive electrode, and the terminal composed of the rivet 5 is a negative electrode. When the internal pressure of the battery rises due to accumulation of gas in the battery during abnormal use such as short-circuiting, overcharging, and reverse charging of the battery, an explosion-proof valve hole provided in the sealing plate 2 is provided. The polypropylene resin film 2b of the part 4 is broken, and the gas inside the battery is discharged, whereby it is possible to prevent a sudden increase in the battery internal pressure.

A battery equipped with the non-aqueous electrolyte battery explosion-proof valve device of the present invention was manufactured as follows. The positive electrode plate is
A mixture of LiCoO ₂ as an active material, carbon black as a conductive agent, and an aqueous dispersion of polytetrafluoroethylene as a binder in a weight ratio of solids of 100: 3: 10 is mixed on both sides of an aluminum foil. , Dried, rolled, and cut into a predetermined size. An aluminum positive electrode current collecting lead plate is welded to this. The negative electrode plate is made of a carbonaceous material as a main material, and a mixture of a styrene-butadiene rubber-based binder in a weight ratio of 100: 5 is applied to both sides of a copper foil, dried and rolled. And cut to a predetermined size. A lead for collecting a negative electrode made of nickel is welded to this. The separator is a polyethylene microporous film. A positive electrode plate and a negative electrode plate are wound around a separator to form an electrode plate group having an oblong upper surface.

The electrode plate current collecting lead 13 is welded to the sealing plate 2 and inserted into the rectangular case 1, and the sealing plate 2 and the case 1 are sealed by laser welding. As shown in FIG. 1, the positive electrode current collecting lead 12 was laser spot welded to the cover plate 2a of the aluminum sealing plate 2, and the negative electrode current collecting lead 13 was resistance welded to the nickel-plated iron washer 7. next,
A predetermined amount of the electrolyte is injected from the injection port 9. In this embodiment,
A pipe with a rubber ring attached to the tip of the liquid inlet 9 is inserted. The pipe has a three-way cock, one connected to the battery, one connected to the vacuum pump, and the other connected to the pump containing the electrolyte.

The pressure inside the battery is reduced by a vacuum pump through a pipe. Next, injection was performed by switching the cock and injecting electrolyte from a pump. Once the inside of the battery is depressurized, the injection of the electrolyte becomes easy. In the electrolyte, ethylene carbonate and diethyl carbonate were mixed in a molar ratio of 1: 3.
A solution obtained by dissolving lithium hexafluorophosphate at a concentration of 1 mol / liter as a solute in the solvent mixed in (1) was used.

(Embodiment 1) An upper insulating gasket 6 for insulating the sealing plate 2 and the rivet 5 and a lower insulating gasket 8 for insulating the sealing plate 2 and the washer 7 will be described.
As a resin material, a polypropylene resin is generally used in a non-aqueous electrolyte battery. This resin is widely used in coin-type lithium batteries and the like because of its good moldability and low cost, but has a problem in heat resistance at high temperatures. Since the sealing plate 2 of the present invention is laser-welded at the case 1 and the laser-welded portion 14, there is a concern that the resin has a thermal effect, and it is desirable that the sealing plate 2 be a relatively thermally stable resin. In this embodiment, polypropylene (hereinafter, referred to as PP), perfluoroalkoxy fluororesin (hereinafter, referred to as PFA), polysulfone resin (hereinafter, referred to as P) are referred to existing data such as organic solvent resistance and heat resistance.
S), polyphenylene sulfide resin (hereinafter referred to as P
PS), and evaluated by combining them with the upper insulating gasket 6 and the lower insulating gasket 8. A sealing plate 2 and a battery were produced using these resins, and a resin leakage test was performed during high-temperature storage to select a resin. Table 1 shows the leakage rate of each battery (each n = 100 cells). In the liquid leakage test method, after storing at -50 ° C. for 1 hour, the process of storing at 100 ° C. for 1 hour was defined as one cycle, and the number of battery leaked products after 1000 cycles was counted.

[0021]

[Table 1]

As shown in Table 1, in the sealing plate structure according to the present invention, the PP which has been conventionally used is
The use of FA, PS, and PPS dramatically improves the liquid leakage resistance. In addition, even if PFA, PS, and PPS are arbitrarily combined with those other than Table 1, the liquid leakage resistance can be secured.

(Embodiment 2) The advantage of providing a needle-like projection 15 on the upper surface of the explosion-proof valve hole 4 of the sealing plate 2 in the lower surface direction of the hole will be described. In the present invention, the explosion-proof valve hole 4 is provided in the cover plate 2a of the sealing plate 2, and the lower surface thereof is covered with a PP film, so that the explosion-proof valve structure is provided. Sometimes the PP film swells up and then breaks. Accordingly, the valve operating pressure is greatly affected by the thickness of the PP film, the shape of the explosion-proof valve hole 4, and the like.

In the present invention, as shown in FIG. 2, a metal plate 16 having a needle-like projection 15 in the lower surface direction of the explosion-proof valve hole 4 is welded to the upper surface of the explosion-proof valve hole 4. When the explosion-proof valve is activated, the breaking position of the explosion-proof valve 3 can be limited to stabilize the operating pressure. A comparison was made of the variation in operating pressure between the case where the needle-like projection 15 was provided on the upper surface of the hole 4 for the explosion-proof valve and the case where the needle-like projection 15 was not provided. The results are shown in Table 2.

[0025]

[Table 2]

As is clear from Table 2, the provision of the needle-like projections 15 makes the variation less stable. Further, in the present embodiment, the metal plate 16 having the needle-like projections 15 is welded. However, as shown in FIG. 3, the needle-like projections 15 are provided by partially deforming the upper surface of the cover plate 2a of the sealing plate 2. May be.

(Embodiment 3) The valve operating pressure of the explosion-proof valve 3 of the sealing plate 2 will be described with reference to FIG. The explosion-proof valve 3 has a battery tightness when using a normal battery, and when the battery internal pressure suddenly rises when the battery is abnormally used, the valve operates reliably to release gas in the battery to the outside. It is necessary to set a proper working pressure. In this embodiment, the PP film and the ultrasonically welded aluminum foil 2 are used as the explosion-proof valve 3.
The valve operating pressure was evaluated using c. Further, a battery provided with the explosion-proof valve 3 was manufactured, and a battery leakage test and an overcharge safety evaluation were performed. Table 3 shows the evaluation results of the valve operating pressure, and Table 4 shows the results of the battery leakage test and the overcharge safety test. The liquid leakage test method was as follows: after storing at -50 ° C for 1 hour,
The process of storing at 0 ° C. for 1 hour is 1000
The number of battery leaks after the cycle was counted. In the overcharge safety test method, it was confirmed whether or not the battery was ignited when the fully charged battery was further charged under uncontrolled 2C.

[0028]

[Table 3]

[0029]

[Table 4]

From Table 4, it can be seen that battery leakage occurs at a thickness of 10 μm or less for both the PP film and the aluminum foil film. It is considered that the valve was activated by gas generation due to decomposition of trace water in the battery or decomposition of the electrolyte solution. Also, P
When the P film is 100 μm or more or the aluminum foil film is 40 μm or more, it is considered that the laser welded portion 14 opens earlier and fires before the valve operation. From the above results and Table 3, the working pressure was 2 to 15
kgf / cm ² is an appropriate operating pressure of the explosion-proof valve.

In this embodiment, a PP film and an aluminum foil film are used, but a polyethylene terephthalate resin film,
A PFA film, PS film, or PPS film may be used.

(Embodiment 4) The advantage that the lower insulating gasket 8 of the sealing plate 2 is bent in the direction of the electrode plate group 11 as shown in FIG. 1 will be described. In the present invention, the washer 7 is disposed via the lower insulating gasket 8 and is caulked with the rivet 5. The washer 7 is welded with the negative electrode current collecting lead 13 of the electrode group 11.
Therefore, at the time of a drop impact of the battery, particularly when the battery is dropped upside down, the electrode plate group 11 shifts upward and the negative electrode current collecting lead 13 bends and bites into the electrode plate group 11,
There is a possibility of causing an internal short circuit by contact with the case 1. On the other hand, by disposing the lower insulating gasket 8 between the electrode group 11 and the sealing plate 2, the electrode group 11
It is considered that the deviation of the battery can be suppressed and the safety of the battery can be secured.

In the present invention, as shown in FIG. 1, the electrode plate group 11 is arranged so that the lower insulating gasket 8 surrounds the metal washer 7 electrically connected to the negative electrode current collecting lead 13 of the electrode plate.
The shape of the electrode plate is bent in the direction shown in FIG. The battery was subjected to a drop impact test with and without such a bent portion of the lower insulating gasket 8, and the results are shown in Table 5.
It was shown to. In the drop impact test method of the battery, the number of occurrences of internal short-circuits in the battery when the battery was turned upside down and dropped 20 times on concrete from a height of 1 m was counted.

[0034]

[Table 5]

As is clear from Table 5, the reliability of the battery can be improved by providing a bent portion of the lower insulating gasket.

[0036]

As described above, according to the present invention, gas can be discharged accurately with respect to a rise in battery internal pressure due to misuse of a battery such as short-circuit, overcharge, reverse charge, or an abnormal situation. ,
Further, it is possible to provide an explosion-proof valve device for a non-aqueous electrolyte battery having high safety and reliability excellent in liquid leakage resistance.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a main part of an explosion-proof valve device according to embodiments 1 and 4 of the present invention.

FIG. 2 is a longitudinal sectional view of a main part of the explosion-proof valve device according to the second embodiment.

FIG. 3 is a longitudinal sectional view of a main part showing another example of the explosion-proof valve device according to the second embodiment.

FIG. 4 is a longitudinal sectional view of a main part of the explosion-proof valve device according to the third embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Case 2 Sealing plate 2a Lid plate 2b Resin film 2c Aluminum foil 3 Explosion-proof valve 4 Explosion-proof valve hole 5 Rivet 6 Upper insulating gasket 7 Washer 8 Lower insulating gasket 9 Filling port 10 Plug 11 Electrode plate group 12 Positive electrode collection Lead 13 Negative current collecting lead 14 Laser welded part 15 Needle-like projection part 16 Metal plate

Claims (10)

[Claims] A case for accommodating an electrode group and an electrolyte therein; a sealing plate for closing an opening of the case and having an explosion-proof valve; and a rivet serving also as a terminal provided on the sealing plate.
A resin upper insulating gasket for insulating the sealing plate and the rivet, and a metal washer for electrically connecting a lower plate of the rivet to a lead plate of the same polarity as the rivet via a resin lower insulating gasket. With
The sealing plate is provided with an explosion-proof valve hole in the lid plate,
An explosion-proof valve device for a non-aqueous electrolyte battery, wherein the lower portion of the explosion-proof valve hole is covered with a resin film. 2. The explosion-proof valve device for a non-aqueous electrolyte battery according to claim 1, wherein the upper insulating gasket is made of a material selected from perfluoroalkoxy fluororesin, polysulfone resin, and polyphenylene sulfide resin. 3. The explosion-proof valve device for a non-aqueous electrolyte battery according to claim 1, wherein the lower insulating gasket is made of a material selected from perfluoroalkoxy fluororesin, polysulfone resin, and polyphenylene sulfide resin. 4. The lower insulating gasket according to claim 1, wherein the lower insulating gasket is bent in the direction of the electrode group so as to surround a metal washer electrically connected to the current collecting lead of the electrode group. Explosion-proof valve device for non-aqueous electrolyte batteries. 5. The resin film disposed under the hole for an explosion-proof valve is one kind of material selected from polyethylene terephthalate resin, perfluoroalkoxy fluororesin, polysulfone resin, and polyphenylene sulfide resin. 2. The explosion-proof valve device for a non-aqueous electrolyte battery according to 1. 6. The resin film disposed below the explosion-proof valve hole has a thickness of 10 to 100 μm.
^2. The explosion-proof valve device for a non-aqueous electrolyte battery according to claim 1, wherein the explosion-proof valve device is designed to be broken by a pressure of 5 kgf / cm ² . 7. The explosion-proof valve of the sealing plate is formed by covering only the lower part of the hole for the explosion-proof valve provided on the cover plate with aluminum foil, or covering the entire lower surface of the cover plate with aluminum foil. , The aluminum foil is 10 to 40 μm
^2. The explosion-proof valve device for a non-aqueous electrolyte battery according to claim 1, wherein the explosion-proof valve device has a thickness of 2 m and is broken by a pressure of ^{2 to} 15 kgf / cm ² . 8. The explosion-proof valve of the sealing plate may cover only the lower part of the hole for the explosion-proof valve provided on the lid plate with aluminum foil by ultrasonic welding, or may ultrasonically weld the entire lower surface of the lid plate. The non-aqueous water according to claim 1, wherein the non-aqueous material is formed by covering with an aluminum foil, wherein the aluminum foil has a thickness of 10 to 40 µm, and is broken by a pressure of ^{2 to} 15 kgf / cm2. Explosion-proof valve device for electrolyte battery. 9. The explosion-proof valve hole upper surface is deformed so as to have a needle-like projection projecting in the center direction of the explosion-proof valve hole portion on the upper surface of the explosion-proof valve hole portion of the sealing plate. The explosion-proof valve device for a non-aqueous electrolyte battery according to the above. 10. The non-aqueous electrolyte battery explosion proof according to claim 1, wherein a metal plate having a needle-like projection in a lower surface direction of the explosion proof valve hole is welded to an upper surface of the explosion proof valve hole of the sealing plate. Valve device.