JP2000348709A - Battery and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate the influence of a supporting method of a joint part to provide a good joint by crimping and jointing a positive electrode tab connected to a power generation element to the bottom of an external can. SOLUTION: A wound coil-like power generation element 3 and a positioning rod 22 in a form integrated with each other are inserted into an external can 1, and a tab hole is threaded with a projection 2 formed on the can bottom, and thereafter, the positioning rod 22 is extracted. At that time, when the positioning rod 22 is rotated, a positive electrode tab 4 can easily be dismounted from the positioning rod 22. The positive electrode tab 4 is crimped and jointed to the can bottom by inserting a crimping flat punch 24 from the central part of the power generation element 3 and by punching the projection 2 on the can bottom. When the crimped part is spot-welded to the positive electrode tab 4, joint strength and reliability are further improved. Therefore, the need of setting troublesome conditions such as pressing force, current, a current carrying period and the shape of the electrode when resistance welding is employed is obviated, and the positive electrode tab 4 can surely be jointed to the bottom of the external can 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a battery, such as a lithium ion secondary battery, in which a pole tab of a wound power generating element is securely fixed to the bottom of a cylindrical bottomed metal can (exterior can). And a method of manufacturing the same.

[0002]

2. Description of the Related Art A sealed secondary battery such as a lithium ion secondary battery generally has a power generating element 32 composed of positive and negative electrodes and the like housed in an iron outer can 31 as shown in FIG. The respective electrodes are connected by pole tabs 33 and 34. In many cases, the outer can is caulked with the sealing body 35 to form an electrically insulated structure.

In connection with the connection between the power generating element and the electrode, for example, in the technique described in Japanese Patent Application Laid-Open No. 10-261399, a current collecting tab provided on the power generating element and an electrode terminal are joined by bolts and nuts.

[0004] In addition, among the sealed secondary batteries, when the outer can is made of iron for the cylindrical battery, the negative electrode tab made of nickel is used for the outer can by resistance welding or ultrasonic welding. Welded to the bottom inside.

[0005] The connection by resistance welding is usually performed as shown in FIG.
6E, the positive electrode tab 33 shown in FIG.
The negative electrode tab 34 of the coil-shaped power generating element 32 on which the negative electrode tab 34 is formed is bent so as to sandwich the insulator 36 (b). In this state, the negative electrode tab 34 is attached to the bottom of the outer can 31.
(C). One electrode 37a of the resistance welding machine is inserted from the center hole of the power generating element 32, and spot welding is performed with the other outer electrode 37b (d).
Thereby, a welded portion 38 is formed, and the negative electrode tab 34 and the outer can 3
1 is made conductive and fixed (e).

However, in recent years, aluminum or aluminum alloys have been used for outer cans in order to reduce the weight of batteries. Accordingly, it has become necessary to connect the aluminum or aluminum alloy, which is the positive electrode tab, to an aluminum or aluminum alloy outer can.

In a sealed secondary battery having a conventional structure, when the outer can and the positive electrode tab are made of aluminum or an aluminum alloy, it is difficult to stably weld aluminum by conventional resistance welding, and the electrode in contact with the welded portion. It is practically difficult to use resistance welding because the sticks stick to the rods and shorten the life of the electrodes. Therefore, when the outer can and the positive electrode tab are made of aluminum or aluminum alloy, the following structure can be newly considered.

(L) A positive electrode tab is disposed on the inner surface of the bottom of an outer can having an opening at the upper end, and the joined portion of the positive electrode tab is supported on the inner surface of the outer can by an ultrasonic horn inserted from the upper opening of the outer can. And joined by ultrasonic welding.

(2) In the same manner as in (1) above, a positive electrode tab is arranged, and a cavity formed in the center of the power generating element 32 from the opening at the upper end of the outer can 31a as shown in a sectional side view in FIG. The positive electrode tab 34a is provided by the support 38 inserted in the 32a.
And the laser beam La is irradiated from the outer surface of the bottom of the outer can 31a and joined by spot welding.

[0010]

However, in a structure in which the current collecting tab provided on the power generating element and the electrode terminal are joined by bolts and nuts, the assembly is complicated and the joining force varies depending on the tightening strength. There is a problem with reliability.

In the sealed secondary battery having the structure (1), an ultrasonic horn for applying ultrasonic vibration to the joint portion when performing ultrasonic welding is provided through the opening at the upper end of the outer can. It is difficult to insert the ultrasonic horn because the space for passing the ultrasonic horn through the center of the electrode coil has a cross-sectional area of only about φ2 mm. Also, due to the height of the sealed secondary battery, the ultrasonic horn becomes thinner and longer, and the total length of the ultrasonic horn becomes about 100 mm. Therefore, sufficient vibration necessary for ultrasonic welding cannot be given to the welded joint. is there.

In the sealed secondary battery having the structure (2), a splash or a molten portion generated during laser welding comes into contact with the support rod, and the support rod itself is welded or melted. Even if the support rod is hollow so that the welded portion of the welded portion of the positive electrode tab does not overlap with the support rod, the diameter of the weld rod is originally about 2 mm. Cannot overlap.

Furthermore, since the positive electrode tab is thin and easily deformed, it is difficult to manage the gap between the surfaces and to confirm whether or not welding has been sufficiently performed inside the outer can.

Further, there is a problem that internal contamination is caused by splash generated at the time of welding. In addition, JI
S alloy number A3004 or A5052, A5182,
A6063, A6061 and the like are used, but these materials have a problem that cracks easily occur by laser welding.

[0015] Also, in the structure for connecting to the iron outer can by resistance welding, the positive electrode tab is supported by the rod inserted from the opening at the upper end of the outer can, so positioning of welding is difficult,
Since the positive electrode tab is thin and easily deformed, it is difficult to manage the gap with the outer can to be joined, and it is also difficult to confirm the quality of the joint, such as displacement of the welding and poor welding. In addition, since there is a large variation in bonding strength and only one bonding portion,
It has disadvantages such as weakness in vibration test and drop test.

Further, since it is considered that the capacity and weight of the battery will further increase in the future, it is conceivable to reduce the thickness of the can material and use aluminum for the can material. With aluminum materials that are difficult to weld, it is difficult to further secure a predetermined joint strength by resistance welding, which originally has a large variation in joint strength.

The present invention has been made based on these circumstances, and even when the outer can and the positive electrode tab of the secondary battery are made of aluminum or an aluminum alloy, there is no influence by the method of supporting the junction of the positive electrode tab, An object of the present invention is to provide a sealed secondary battery having a structure in which a positive electrode tab is satisfactorily joined to the inner surface of the bottom of an outer can and a method for manufacturing the same.

[0018]

According to the first aspect of the present invention, a metal outer can, a power generating element housed in the outer can and wound with a positive electrode and a negative electrode, The electrolyte contained in the outer can and the sealing body that closes the opening of the outer can and is electrically insulated from the outer can, and the positive electrode and the negative electrode of the power generating element are electrically connected to the outer can and the sealing body, respectively. In the battery having the connected structure, the outer can is formed by caulking and joining the positive electrode tab connected to the power generating element to the bottom of the can.

According to the second aspect of the present invention,
A battery is provided, wherein a protrusion for caulking and fixing the positive electrode tab is formed on a bottom of the outer can.

According to the third aspect of the present invention,
The battery is characterized in that the positive electrode tab is provided with a tab hole that fits into the protrusion.

According to the means of the invention of claim 4,
The battery is characterized in that the outer can and the positive electrode tab are formed of aluminum or an aluminum alloy.

According to the fifth aspect of the present invention,
A power generating element in which a positive electrode and a negative electrode are wound is housed inside an outer can formed in a metal bottomed cylindrical shape, and the positive electrode and the negative electrode of the power generating element are electrically connected to the outer can and a sealing body, In the method for producing a battery in which a nonaqueous electrolytic solution is injected into an outer can through an opening and the opening is closed, a positive electrode tab connected to the power generation element is crimped to a protrusion on a bottom of the outer can. A method for producing a battery characterized by the following.

According to the means of the invention of claim 6,
A method for manufacturing a battery, characterized in that the positive electrode tab is provided with a tab hole which fits with the protrusion in advance.

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A sealed secondary battery using a non-aqueous electrolyte according to the present invention will be described below in detail with reference to the drawings, taking a cylindrical sealed secondary battery as an example. Here, the cylindrical shape means that the shape when the outer can is cut at the surface including the power generation element is a circle or a shape similar to the circle.

FIG. 1 is a longitudinal sectional view showing a non-aqueous sealed secondary battery according to the present invention, for example, a cylindrical sealed lithium ion secondary battery.

The bottomed cylindrical outer can 1 also serves as a positive electrode terminal,
It is made of aluminum or aluminum alloy with a thickness of 0.3mm, diameter φ1mm, height 0.5mm at the center of the bottom of the can
The tab hole 5 of the positive electrode tab 4 extending from the power generating element 3 is inserted into the protrusion 2 of the degree, and is caulked and joined.

A power generating element 3 is mounted on a bottom surface inside the outer can 1. The power generating element 3 includes a positive electrode 7 and a separator 8
The cathode 7 is connected to the cathode tab 4 joined to the inner surface of the bottom of the outer can 1.

On the other hand, the outer can 1 is beaded near the opening at the upper end. The sealing body 10 engaged with the opening is formed of iron, nickel, copper or an alloy thereof, and a negative electrode tab is attached to the negative electrode 9 of the power generating element 3 with an electrode body holder 11 provided above the power generating element 3 interposed therebetween. 12. The sealing body 10 is caulked using a gasket 14 after the electrolyte 13 is injected into the outer can 1, and the outer can 1
Are hermetically sealed.

Next, a description will be given of a method of manufacturing a sealed secondary battery having these configurations.

First, as shown in FIGS. 2 (a) and 2 (b), a protrusion 2 having a diameter of about 1 mm and a height of about 0.5 mm is formed at the center of the bottom of the outer can 1 and is backward-extruded (impact). An outer can 1 manufactured by molding is prepared. In this backward extrusion, as shown in FIG. 2 (a), an aluminum block is mounted on a mold 20, and a concave portion 21a for forming the projection 2 is formed thereon.
A punch 21 having a clearance corresponding to the thickness of the outer can 1 between 0 and 0 is inserted into a mold 20 and an aluminum block is pressed to form the outer can 1 shown in FIG.

On the other hand, as shown in FIG. 3A, the power generating element 3 has a positive electrode 7 and a negative electrode 9 wound in a coil shape with a separator 8 interposed therebetween. A tab hole 5 having a diameter of 2 mm is formed with a certain clearance so that the projection 2 of the outer can 1 can be securely inserted. The insulating plate 13 is provided with a through-hole 13a substantially at the center in the same extent as the tab hole 5, and a part of the disk is cut straight. When the cut surface 13 b is pressed against the positive electrode tab 4 and the positive electrode tab 4 is bent toward the insulating plate 13, the through hole 13 a and the tab hole 5 of the positive electrode tab 4 just pass through.

Next, as shown in FIG. 3 (b), when the power generating element 3 is inserted into the outer can 1, it is positioned so that the tab hole 5 is securely inserted into the projection 2 on the bottom of the can. Then, the hollow positioning rod 22 is inserted into the center of the coiled power generating element 3. Then, as shown in FIG. 3C, the positive electrode tab 4 is lightly hit with the temporary fixing punch 23 so as to be fixed to the positioning rod 22 and integrated. As a result, when the insulating plate 13 is inserted into the outer can 1, the insulating plate 13 is fixed so that the center of the insulating plate 13 coincides with the center of the bottom of the outer can 1. When the insert 3 is inserted into the outer can 1, the tab hole 5 of the positive electrode tab 4 does not deviate from the center.

Next, the wound coil-shaped power generating element 3 and the positioning rod 22 are inserted into the outer can 1 as shown in FIG. Projection 2 installed on can bottom
Then, the positioning rod 22 is removed after the tab hole 5 is passed through. At this time, if the positioning rod 22 is rotated, the positive electrode tab 4
Can be easily removed from the positioning rod 22.

Then, as shown in FIG. 4 (b), a flat punch 24 for caulking is inserted from the center of the power generating element 3 and the projection 2 installed on the bottom of the can is hit, so that FIG. Then, the can bottom and the positive electrode tab 4 are caulked and joined as shown in FIG. In addition,
If the caulked portion and the positive electrode tab 4 are spot-welded, the joining strength and reliability are further improved.

The location where the positive electrode tab 4 is joined to the outer can 1 is not limited to the bottom of the can, but a projection can be provided on the can lid and the side wall of the can.

Next, after the electrode body retainer 11 shown in FIG. 1 is arranged on the power generating element 3, the vicinity of the upper end opening on the side surface of the outer can 1 is beaded.

Subsequently, the electrolytic solution 13 is injected into the inside of the outer can 1 from the opening at the upper end of the outer can 1.

As the electrolytic solution 13, for example, in the case of a lithium ion secondary battery, an electrolyte such as lithium perchlorate, lithium borofluoride, lithium hexafluoride, lithium phosphorus hexafluoride is used as an electrolyte such as ethylene carbonate or propylene carbonate. Use those dissolved in a suitable organic solvent.

Next, the negative electrode tab 12 is connected to the negative electrode 9 of the power generating element 3.
And the other end is connected to a sealing body 10 formed of iron, nickel, copper or an alloy thereof.

Next, the sealing body 10 is airtightly joined to the opening of the outer can 1 by caulking via a gasket 14 made of polypropylene.

As described above, according to the structure of the present invention, conventionally, when joining the electrode tab and the can bottom by spot welding, there is a large variation in joining strength and the material to be welded is attached to the electrode rod of the resistance welding machine. Although the electrode rods had to be dressed because the adhesion also had an adverse effect on the joining strength, the joining method by caulking according to the present invention required a pressing force, a current, and an electric current when using resistance welding as in the prior art. time,
There is no need to set the electrode shape and complicated conditions, and it is not necessary to consider the life of the electrode of the resistance welding machine, and the positive electrode tab 4 and the can bottom of the outer can 1 can be securely joined.

[0042]

According to the present invention, even when the outer can and the positive electrode tab are made of aluminum or aluminum alloy,
The positive electrode tab can be favorably joined to the bottom of the outer can.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing a cylindrical sealed lithium ion secondary battery according to the present invention.

FIGS. 2A and 2B are explanatory diagrams of a method for manufacturing an outer can.

3 (a) to 3 (c) are explanatory views of a step of connecting a positive electrode tab of a cylindrical sealed lithium ion secondary battery according to the present invention.

FIGS. 4A to 4C are explanatory views of a step of connecting a positive electrode tab of a cylindrical sealed lithium ion secondary battery to an outer can according to the present invention.

FIG. 5 is a vertical sectional view showing a conventional cylindrical sealed lithium ion secondary battery.

FIGS. 6A to 6E are explanatory views of a process of connecting a negative electrode tab of a conventional cylindrical sealed lithium ion secondary battery to an outer can.

FIG. 7 is a cross-sectional side view of a sealed lithium ion secondary battery in which tabs are joined by spot welding using laser light from the outer surface of the bottom of the outer can.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Outer can, 2 ... Protrusion, 3 ... Power generation element, 4 ... Positive electrode tab,
5: Tab hole, 24: Flat punch

Continuing from the front page (72) Inventor Fujio Takahashi 33F, Shinisogo-cho, Isogo-ku, Yokohama-shi, Kanagawa Prefecture F-term in the Toshiba Production Technology Center (reference) 5H022 AA09 BB01 BB19 CC08 CC12 CC13 CC19 EE04

Claims (6)

[Claims] 1. A metal outer can, a power generation element housed in the outer can and wound with a positive electrode and a negative electrode, an electrolytic solution housed in the outer can, and an opening of the outer can. A sealed body that is closed and electrically insulated from the outer can, and a battery having a structure in which the positive electrode and the negative electrode of the power generating element are electrically connected to the outer can and the sealed body, respectively, wherein the outer can is A battery, wherein the positive electrode tab connected to the power generating element is caulked to the bottom of a can and joined. 2. The battery according to claim 1, wherein a protrusion for caulking and fixing the positive electrode tab is formed on a bottom of the outer can. 3. The battery according to claim 1, wherein the positive electrode tab is provided with a tab hole that fits into the protrusion. 4. The battery according to claim 1, wherein the outer can and the positive electrode tab are formed of aluminum or an aluminum alloy. 5. A power generating element in which a positive electrode and a negative electrode are wound is accommodated in an outer can formed in a metal-made bottomed cylindrical shape,
The method of manufacturing a battery in which a positive electrode and a negative electrode of the power generation element are electrically connected to an outer can and a sealing body, and a nonaqueous electrolytic solution is injected into the outer can through an opening to close the opening. And crimping the positive electrode tab connected to the power generating element to the protrusion on the bottom of the can. 6. The positive electrode tab is provided with a tab hole for engaging with the projection in advance.
A method for producing the battery according to the above.