JPH0950799A - Safety valve device and non-aqueous electrolyte secondary battery - Google Patents

Abstract

(57) Abstract: An object of the present invention is to enable reliable release even at a relatively low pressure without reducing the thickness of a metal foil constituting a safety valve more than necessary. SOLUTION: A cleaving valve 22 made of metal foil provided so as to seal an opening 10b of a closed container 10, and the cleaving valve 22.
A hollow needle 23b fixed to the cleaving valve 22 so that the tip of the cleaving valve 22 abuts on the outside.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a safety valve device and a non-aqueous electrolyte secondary battery suitable for use in a large-capacity power supply device used in, for example, an electric vehicle.

[0002]

2. Description of the Related Art Generally, in a non-aqueous electrolyte secondary battery, gas or the like is generated inside the battery container during abnormal charging / discharging.
In order not to cause inconvenience due to the generation of this gas or the like, a safety valve device 13 as an internal pressure release device is provided in this battery container.
Is provided.

Conventionally, as shown in FIGS. 5A and 5B, a safety valve device 13 provided in a battery container of such a non-aqueous electrolyte secondary battery has been used. 5A shows a cross-sectional view of the safety valve device 13, and FIG. 5B shows a top view thereof. In FIG. 5, 13a shows a safety valve which is a cleaving valve made of metal foil, for example, aluminum foil. 10b has an opening 10b provided at the center of the upper surface 10a.
A pressing metal fitting 13c having a pressure release hole 13d of a predetermined size is screwed and fixed to the central portion through a packing 13b so as to cover the.

In the safety valve device 13, the safety valve 13a is opened when the atmospheric pressure in the battery container 10 becomes large, and the atmospheric pressure in the battery container 10 is released.

[0005]

The safety valve device 13 for such a non-aqueous electrolyte secondary battery is accompanied by a destructive force when the safety valve 13a is set up so that it cleaves at too high pressure.
It is desired that a cleave at low pressure.

However, in order to open the safety valve 13a at a low pressure, it is necessary to thin the metal foil forming the safety valve 13a. When the metal foil is thinned, there is a possibility that the metal foil may be broken by vibration or the like. There is a disadvantage that it is difficult to use as a non-aqueous electrolyte secondary battery as a power source in a place where vibrations are large, such as in an electric vehicle. In a place where the operating temperature atmosphere fluctuates greatly, the internal pressure in the battery container 10 of this non-aqueous electrolyte secondary battery fluctuates up and down, and this safety valve 13a is repeatedly stressed. There was an inconvenience that it was difficult to cleave.

The present invention has been made in view of the above problems, and an object of the present invention is to enable reliable release even at a relatively low pressure without reducing the thickness of the metal foil constituting the safety valve more than necessary.

[0008]

The safety valve device of the present invention is a cleaving valve made of metal foil provided so as to seal the opening of a hermetically sealed container, and is fixed outside the cleaving valve so that the tip of the cleaving valve abuts the cleaving valve. And a hollow needle.

According to the present invention, when the internal pressure of the closed container rises and the cleaving valve swells to a predetermined size (when the internal pressure reaches a predetermined pressure), the hollow needle pierces the cleaving valve and cleaves. It can be cleaved at a relatively low pressure without making the thickness of the metal foil constituting the valve unnecessarily thin. Since the present invention uses a hollow needle, when this internal pressure is relatively low, the hollow needle penetrates Atmospheric pressure is released through the hole, and when the internal pressure is relatively high, the cleaving valve is cleaved, and the internal pressure of the closed container can be surely released.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An example in which the safety valve device of the present invention and a non-aqueous electrolyte secondary battery are applied to a lithium ion secondary battery will be described below with reference to the drawings.

In FIG. 3, 10 has a thickness of 0.5, for example.
1 shows a closed flat rectangular battery container made of a nickel-plated iron plate of mm, in which a predetermined plurality of positive electrode electrodes 2 and negative electrode electrodes 3 are arranged in a negative electrode electrode 3, a separator 8, The laminated body 14 in which the positive electrode 2, the separator 8, the negative electrode 3, ...

The negative electrode 3 is made by firing in an inert gas stream and then pulverizing it to obtain 90 parts by weight of carbon having an average particle size of 20 μm, and a vinylidene fluoride resin as a binder.
A slurry in which 0 part by weight of N-methylpyrrolidone is dispersed is applied as a negative electrode active material 6 on both surfaces of a negative electrode current collector 7 made of a copper foil having a thickness of 10 μm as shown in FIG.
A negative electrode original plate having a thickness of μm was prepared, and this negative electrode original plate was cut into a size of 82 mm × 284 mm, leaving an uncoated portion of the negative electrode active material 6 to be a lead portion of the negative electrode 3 in a part of the negative electrode current collector 7. It was formed.

The positive electrode 2 is made of L having an average particle size of 15 μm.
A slurry in which 91 parts by weight of iCoO ₂ powder, 6 parts by weight of graphite as a conductive material, and 3 parts by weight of vinylidene fluoride resin as a binder were dispersed in N-methylpyrrolidone was used as a positive electrode active material as shown in FIG. As No. 4, the positive electrode current collector 5 made of aluminum foil is coated on both sides to have a thickness of 150.
A positive electrode raw plate having a thickness of μm was prepared, and this positive electrode raw plate was cut into a size of 77 mm × 279 mm with a part of the positive electrode current collector 5 left uncoated with the positive electrode active material 4 to be the lead part of the positive electrode 2. It was formed.

The separator 8 has a thickness of 38 μm and is 87
It is composed of a microporous polypropylene film cut into mm × 289 mm.

In this example, as shown in FIG. 3, a plurality of the above-mentioned negative electrode 3 and a plurality of the above-mentioned positive electrode 2 are alternately laminated via the above-mentioned separator 8 to form a rectangular laminate 14.
To form In this case, the lead portion of the negative electrode 3 and the lead portion of the positive electrode 2 are positioned on opposite sides.

The lead portion of the negative electrode 3 is welded to the negative electrode lead body 12a made of copper by ultrasonic welding, and the lead portion of the positive electrode 2 is welded to the positive electrode lead body 11a made of aluminum by ultrasonic welding. Laminated body 1 in which the positive electrode lead body 11a and the negative electrode lead body 12a are welded
4 is stored in the flat rectangular battery container 10. Further, in this example, as shown in FIG. 3, the positive electrode lead body 11a and the negative electrode lead body 12a are connected to the external positive electrode terminal 11 and the external negative electrode terminal 12, respectively.

An electrolytic solution 9 in which LiPF ₆ is dissolved at a rate of 1 mol / l in a mixed solvent of propylene carbonate and dityl carbonate is injected into the closed flat rectangular battery container 10. In this case, the electrolytic solution 9 is injected by opening the mouth of the safety valve device 20 described later.

In this example, a safety valve device 20 is provided at the center of the upper surface 10a on which the external positive electrode terminal 11 and the external negative electrode terminal 12 of the closed flat rectangular battery container 10 are provided.

In this example, the safety valve device 20 is constructed as shown in FIGS. That is, a circular opening 10b having a predetermined diameter is formed at the center of the upper surface 10a of the closed flat rectangular battery container 10, and a safety valve fixing body 21 is airtightly fixed to the opening 10b. The safety valve 22, which is a cleavage valve made of aluminum foil, is screwed and fixed via the pedestal 23 with a lid-type pressing metal fitting 24 having a predetermined pressure release hole 24a.

In this case, the packing 25 is used, and the opening 10b is sealed by the safety valve 22 which is a cleavage valve made of the aluminum foil.

Aluminum foil 22 constituting this cleaving valve
The thickness of this was 30 μm in this example.

The pedestal 23 is made of stainless steel, has a circular shape having substantially the same diameter as that of the aluminum foil 22 constituting the cleaving valve as shown in FIGS. 2A and 2B, and has a thick cleaving valve pressing portion 23a on the outer periphery thereof. A hollow needle 23b is provided at the center of the pedestal 23 on the side facing the aluminum foil 22, which is a cleavage valve.

As shown in FIGS. 1A and 1B, the hollow needle 23b has a through hole 23c that penetrates the center of the needle from one side to the other side.
The hollow needle 23b is inclined so that its tip facing the cleaving valve 22 is sharpened.

In this case, the hollow needle 23 of the pedestal 23 is also used.
The distance between the tip of b and the aluminum foil 22 constituting the cleaving valve is determined according to the atmospheric pressure at which the cleaving valve 22 is to be cleaved.

Further, a predetermined pressure release hole 23d is formed in this pedestal 23 as shown in FIG. 2B.

Since this example is constructed as described above, when the operation of the non-aqueous electrolyte secondary battery is normal, the air pressure in the sealed battery container 10 does not rise and the cleaving valve of the safety valve device 20 is opened. The relationship between 22 and the hollow needle 23b is as shown in FIG. 1A, and this non-aqueous electrolyte secondary battery operates well.

When an abnormality occurs in the operation of the non-aqueous electrolyte secondary battery, the air pressure of the hermetically sealed battery container 10 rises, and in response to the rise in the air pressure, the aluminum foil forming the cleaving valve 22. Swells, the aluminum foil 22 and the hollow needle 23b come into contact with each other, and the stress on the portion of the aluminum foil 22 hit by the hollow needle 23b locally increases,
The aluminum foil 22 is cleaved at a lower pressure than the cleavage of the aluminum foil 22 only at this atmospheric pressure.

In this case, when the internal pressure of the battery container 10 rises and the cleaving valve 22 expands to a predetermined size (when the internal pressure reaches a predetermined pressure), the hollow needle 23b opens the cleaving valve 22 as shown in FIG. 1B. When the internal pressure is relatively low at this time, even if the pierced crack does not spread and the aluminum foil 22 clings to the needle tip of the hollow needle 23b, the air pressure is released through the through hole 23c of the hollow needle 23b. There is a profit to be made.

When the hollow needle 23b pierces the cleaving valve 22, the cleaving valve 22 has a relatively high internal pressure.
Has an advantage that the crack spreads and splits, and the internal pressure of the battery container 10 can be surely released.

In the above-mentioned embodiment, an example in which an aluminum foil is used as the cleaving valve has been described, but it goes without saying that the cleaving valve may be another metal foil.

Further, in the above-mentioned embodiments, the example in which the present invention is applied to the lithium ion secondary battery is described, but it may be applied to other non-aqueous electrolyte secondary batteries, and the safety valve device of the present invention is applied to other types. Of course, it may be used as a safety valve for a closed container.

Further, the present invention is not limited to the above-mentioned embodiments, and it goes without saying that various other configurations can be adopted without departing from the gist of the present invention.

[0033]

According to the present invention, when the internal pressure of the closed container rises and the cleaving valve swells to a predetermined size (when the internal pressure reaches a predetermined pressure), the hollow needle pierces the cleaving valve,
There is an advantage that the metal foil forming the cleaving valve can be cleaved at a relatively low pressure without making the thickness of the metal foil thinner than necessary.

Further, according to the present invention, since the hollow needle is used, when the internal pressure is relatively low, even if the cleaving valve clings to the needle tip of the hollow needle without spreading the pierced crack, The benefit is that the air pressure is released through the through hole of this hollow needle.

[Brief description of drawings]

FIG. 1 is a sectional view showing an example of a main part of an embodiment of a safety valve device of the present invention.

FIG. 2A is a sectional view showing an embodiment of the safety valve device of the present invention. B is a plan view showing an example of a pedestal.

FIG. 3 is a cross-sectional view showing an example of a lithium ion secondary battery.

FIG. 4 is a diagram provided for explaining a lithium ion secondary battery.

FIG. 5 is a diagram showing an example of a conventional safety valve device.

[Explanation of symbols] 2 positive electrode 3 negative electrode 8 separator 10 flat rectangular battery container 10a upper surface 10b opening 20 safety valve device 22 cleaving valve (safety valve) 23 pedestal 23b hollow needle 23c through hole

Claims (2)

[Claims] 1. A cleaving valve made of metal foil provided so as to seal an opening of a hermetic container, and a hollow needle fixed to the cleaving valve outside the cleaving valve so that the tip of the cleaving valve abuts. Characteristic safety valve device. 2. A non-aqueous electrolyte secondary battery in which a laminate in which a positive electrode and a negative electrode are sequentially laminated via a separator is housed in a battery container is provided with an opening at a predetermined position of the battery container. A non-aqueous electrolyte solution is provided with a cleaving valve made of metal foil so as to seal the opening, and a hollow needle fixed outside the cleaving valve so that the tip of the cleaving valve abuts the cleaving valve. Next battery.