JP2007157350A - Method of manufacturing sealed battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing a sealed battery, sealing a metal plate covering a plug for closing an electrolyte pouring hole installed in the battery by welding with high energy beams such as laser beams in a short time, and forming an irradiation mark for discriminating a manufacturing history. <P>SOLUTION: In the method of manufacturing the sealed battery sealing the electrolyte pouring hole by closing the electrolyte pouring hole installed in the battery with the plug, and welding at least two portions 32, 33 in the periphery of the metal plate 29 part covering the plug to a sealing cover with high energy beams, the irradiation mark 36 for discrimination is formed with the high energy beams during relative moving of a working head from a welding finishing point of a first welding portion 34 with the high energy beams to a welding starting point of a second welding portion 35. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a sealed battery in which an electrolyte injection hole of a battery is sealed using a high energy beam welding method, and in particular, a plug for closing the battery injection hole provided in the battery is covered with a metal plate. In addition, the present invention relates to a method for manufacturing a sealed battery that can weld and seal a metal plate with a high energy beam such as a laser beam in a short time and also form an irradiation mark for discrimination.

  With the rapid spread of portable electronic devices, the required specifications for the batteries used for them are becoming stricter year by year, and in particular, small and thin, high capacity, excellent cycle characteristics, and stable performance are required. Yes. In the field of secondary batteries, lithium non-aqueous electrolyte secondary batteries, which have a higher energy density than other batteries, are attracting attention, and the proportion of lithium non-aqueous electrolyte secondary batteries shows a significant increase in the secondary battery market. ing.

This lithium non-aqueous electrolyte secondary battery mainly uses a carbonaceous material such as graphite capable of occluding and releasing lithium ions as a negative electrode active material, and contains lithium-containing cobalt oxide (LiCoO ₂ ), lithium-containing manganese oxide (LiMn ₂ O _4). A lithium-containing transition metal oxide such as) is widely used as a small, lightweight and high-capacity battery.

  By the way, in a device in which this type of non-aqueous electrolyte secondary battery is used, the space for storing the battery is often a square (flat box shape). Non-aqueous electrolyte secondary batteries are often used. An example of such a square sealed nonaqueous electrolyte secondary battery will be described with reference to the drawings.

  FIG. 4 is a perspective view showing a rectangular sealed nonaqueous electrolyte secondary battery manufactured in the related art cut in the vertical direction. The non-aqueous electrolyte secondary battery 10 accommodates a flat spiral electrode body 14 in which a positive electrode plate 12 and a negative electrode plate 11 are wound via a separator 13 inside a rectangular battery outer can 15. A rectangular battery outer can 15 is sealed with a sealing lid 16.

  The flat spiral electrode body 14 is wound such that the positive electrode plate 12 is exposed at the outermost periphery, and the exposed outermost positive electrode plate 12 is a rectangular battery outer can 15 that also serves as a positive electrode terminal. It is in direct contact with and electrically connected to the inner surface. The negative electrode plate 11 is formed in the center of the sealing lid 16 and is electrically connected to a negative electrode terminal 18 attached via an insulator 17 via a current collector 19.

  Since the rectangular battery outer can 15 is electrically connected to the positive electrode plate 12, a flat spiral electrode body 14 is used to prevent a short circuit between the negative electrode plate 11 and the rectangular battery outer can 15. By inserting the insulating spacer 20 between the upper end of the battery and the sealing lid 16, the negative electrode plate 11 and the rectangular battery outer can 15 are electrically insulated.

  In this rectangular nonaqueous electrolyte secondary battery, after the flat spiral electrode body 14 is inserted into the rectangular battery outer can 15, the sealing lid 16 is laser welded to the opening of the rectangular battery outer can 15. Thereafter, a non-aqueous electrolyte is injected from the electrolyte injection hole 21 to seal the electrolyte injection hole 21. Such a rectangular sealed non-aqueous electrolyte secondary battery has an excellent effect that there is little wasted space during use, and battery performance and battery reliability are high.

  Here, the process of laser welding the sealing lid of the sealed nonaqueous electrolyte secondary battery disclosed in Patent Document 1 to the opening of the rectangular battery outer can will be described with reference to FIG. In FIG. 5, the same components as those of the nonaqueous electrolyte secondary battery shown in FIG. A sealing lid 16 of a sealed nonaqueous electrolyte secondary battery disclosed in the following Patent Document 1 has a substantially rectangular shape, and a negative terminal 18 attached via an insulator 17 is provided at the center. In addition, an electrolyte injection hole 21 is provided at the peripheral edge. After the sealing lid 16 is attached to the inner edge of the opening of the outer can 15, the laser beam oscillated in a pulsed manner is intermittently sent in the circumferential direction to the joint between the sealing lid 16 and the battery outer can 15 in an orderly manner. By irradiating, a weld bead row 22 is formed, and a weld bead row 23 on the laser beam irradiation start side and a weld bead row 24 on the irradiation end side are overlapped to form a lap 25, thereby distinguishing these laps 25. It can be used as an irradiation mark (marking).

  On the other hand, the electrolyte solution injection hole 21 provided in the sealing lid 16 needs to be sealed after the electrolyte solution is injected, but here, the electrolyte solution of the sealed nonaqueous electrolyte secondary battery disclosed in Patent Document 2 below. A method for sealing the injection hole will be described with reference to FIGS. 6 is a longitudinal sectional view showing a state in which the electrolyte injection hole and the sealing plug of the sealing lid are laser-welded. FIG. 7 is a plan view of the same, and FIG. 6 and FIG. The same components as those of the nonaqueous electrolyte secondary battery shown in FIG.

  The sealing plug 26 for sealing the electrolyte injection hole 21 disclosed in the following Patent Document 2 is formed of the same material (for example, aluminum) as the sealing lid 16, and has a conical surface or a pyramidal surface 27 around it. It is provided with a substantially flat plate shape. This sealing plug 26 is placed on the sealing lid 16 so as to close the electrolyte injection hole 21, and then oscillates in a pulse manner over the entire conical surface or pyramidal surface 27 of the side surface of the sealing plug 26. The light 28 is welded to the sealing lid 16 so as to form a weld bead array 22 by intermittently irradiating the light 28 in order in the circumferential direction.

Japanese Patent Laying-Open No. 2003-31186 (Claims, paragraphs [0013] to [0018], FIGS. 1 to 3) JP 2000-90891 A (claims, paragraphs [0011] to [0013], FIGS. 1 to 3)

  According to the sealed nonaqueous electrolyte secondary battery disclosed in Patent Document 1, when laser-welding the sealing lid to the opening of the rectangular battery outer can, the laser irradiation start side and the irradiation end side Since a lap was formed by superimposing the welding traces of the lap and this lap could be used as an irradiation trace for discrimination, the formation of an irradiation trace for discriminating the manufacturing history for each manufactured battery was manufactured. Although it can be performed during the process, it does not increase the number of steps for forming an irradiation mark for separate determination, and it is possible to measure the shortening of the manufacturing time and the reduction of the manufacturing cost. There is no suggestion regarding how to seal the electrolyte injection hole provided in the sealing lid.

  On the other hand, in Patent Document 2 described above, in order to seal the electrolyte injection hole provided in the sealing lid of the nonaqueous electrolyte secondary battery, the laser beam is applied to the entire conical surface or the pyramidal surface of the side surface of the sealing plug. Although it is shown that it is welded to the sealing lid so as to form a weld bead array by intermittently irradiating while feeding in order in the circumferential direction, it forms an irradiation trace for discriminating the manufacturing history There is no suggestion about this.

  Usually, in the manufacturing process of a sealed nonaqueous electrolyte secondary battery, the step of laser welding the sealing lid to the opening of the battery outer can and the step of sealing the electrolyte injection hole provided in the sealing lid are separated. As a result, separate laser welding processing heads are used in each step. That is, in the process of laser welding the sealing lid of the sealed nonaqueous electrolyte secondary battery to the opening of the battery outer can, or in the process of laser welding the sealing plug to the electrolyte injection hole provided in the sealing lid, Since the time required for laser welding is long, a single laser welding processing head cannot provide sufficient processing capability. Therefore, a laser welding apparatus having a plurality of processing heads is used, and multiple batteries are welded simultaneously. I'm trying to do it. However, defective products may frequently occur in batteries welded with a specific processing head due to deterioration or damage of optical components in each processing head.

  Therefore, not only the step of laser welding the sealing lid of the sealed nonaqueous electrolyte secondary battery to the opening of the rectangular battery outer can, but also the step of laser welding the sealing plug to the electrolyte injection hole provided in the sealing lid However, it is necessary to form an irradiation mark for discriminating the manufacturing history. In this case, as disclosed in Patent Document 1, a lap is formed by overlapping the bead row on the laser irradiation start side and the bead row on the irradiation end side around the sealing plug, and this lap is discriminated. It may be used as an irradiation mark for the laser beam, or it may be possible to move the laser irradiation head to a position different from the laser welding location of the sealing plug to form a determination irradiation mark at that position. If such a method is employed, it takes time to move the laser head and form the irradiation mark for discrimination, and this causes a problem that the manufacturing time becomes long. The problem of this long manufacturing time is that even if the time required for laser welding of individual batteries is short, it will become enormous if accumulated in mass production applications. Is required.

  On the other hand, as a means for sealing the electrolyte injection hole provided in the nonaqueous electrolyte secondary battery, for example, a rubber plug is fixed to the surface of the metal plate, the electrolyte injection hole is closed with the rubber plug, and the metal plate is used as a sealing lid. A method for sealing an electrolyte injection hole provided in a sealing lid by laser welding has been proposed. In this case, since there is a sealing ability of the electrolyte injection hole by the rubber plug, the necessary sealing degree can be ensured without necessarily laser welding the entire periphery of the metal plate, which is necessary for the laser welding process. Can be shortened. Even in this case, in order to give an irradiation mark for discriminating the manufacturing history, a wrap is formed as in the method disclosed in Patent Document 1, or the laser processing head is moved separately. As such, it does not lead to a significant reduction in the time required for laser welding.

  The present invention has been made to solve the above-described problems of the prior art, and plugs the electrolyte injection hole provided in the outer can of the battery or the sealing lid with a plug, and plugs the plug with a metal plate. To provide a manufacturing method of a sealed battery that covers and seals a metal plate in a short time by welding with a high energy beam such as a laser beam and can also form an irradiation mark for discrimination. Objective.

In order to achieve the above object, the invention of a method for manufacturing a sealed battery according to claim 1 of the present application is as follows.
Plug the electrolyte injection hole provided in the battery with a stopper, cover the stopper with a metal plate, and seal the electrolyte injection hole by welding at least two places on the periphery of the metal plate to the sealing lid with high energy rays In the manufacturing method of the sealed battery,
An irradiation mark for discrimination is formed by the high energy line while moving the processing head relatively from the end point of the first weld bead line by the high energy line to the start point of the second weld bead line. Features.

  In the invention according to claim 1, even when welding with a high energy beam, the sealed battery is fixed and the processing head is moved, or the processing head is fixed and the sealed battery is, for example, XY. It may be moved by using a stage. The sealed battery may be not only a non-aqueous electrolyte secondary battery, but also a non-aqueous electrolyte primary battery or a secondary battery and a primary battery using an aqueous electrolyte. Further, the electrolyte solution injection hole may be provided in the outer can or the sealing lid.

  The invention according to claim 2 is the method for manufacturing a sealed battery according to claim 1, wherein the metal plate has a polygonal shape, an elliptical shape, or a circular shape, and the first welding portion and the second welding portion. The portions are provided on the peripheral edges facing each other.

  In addition, in the invention which concerns on Claim 2, when the said metal plate is a polygonal shape, it is preferable that it is a square shape, and the corner | angular part of a polygon may be dropped. Furthermore, at the first and second welding locations, welding may be performed so as to form a single welding bead, or welding may be performed so that a plurality of welding beads overlap each other.

  According to a third aspect of the present invention, in the method for manufacturing a sealed battery according to the first or second aspect, the high energy beam is a laser beam or an electron beam.

  The present invention has the following excellent effects by adopting the manufacturing method as described above. That is, according to the invention according to claim 1, since the sealing ability of the plug against the electrolyte injection hole can be utilized, the necessary sealing is not necessarily performed by welding the entire periphery of the metal plate covering the plug with a high energy ray. The degree can be secured. Therefore, according to the invention according to claim 1, if at least two places on the periphery of the metal plate are welded to the sealing lid, a predetermined sealing strength can be secured, and at the time of welding at least two places, Although it is necessary to relatively move the machining head from the welding end point of the first welding point to the welding start point of the second welding point by the high energy ray, an irradiation mark for discrimination is formed during this movement. As a result, it is not necessary to relatively move the machining head to form an irradiation trace for distinction separately, and the time required for the welding process of the metal plate with high energy rays can be shortened. become.

  Further, according to the invention according to claim 2, since the first welded portion and the second welded portion are provided on the peripheral edges facing each other, the stopper and the metal plate can be firmly fixed, and the sealing degree is good. A sealed battery can be manufactured.

  According to the third aspect of the present invention, both a laser beam and an electron beam are conventionally used as high energy beams for welding, and a prismatic battery with good welded portion reliability and quality can be obtained.

  Hereinafter, the best mode for carrying out the present invention will be described in detail with reference to FIGS. 1 to 3 by taking as an example a case where a rectangular sealed battery and a laser beam as a high energy beam are used. However, the examples shown below are merely examples for embodying the technical idea of the present invention, and are not intended to specify the present invention as examples. The present invention can be equally applied to various changes made without departing from the technical idea shown in the claims, such as when a circular sealed battery or an electron beam is used as a high energy beam.

  FIG. 1 is a diagram showing each manufacturing process of the sealed battery according to the example, FIG. 1A is a state of a sealing lid after electrolyte solution injection, and FIG. 1B is a diagram in which the electrolyte solution injection hole is closed with a metal plate. FIG. 1C is a plan view showing a state where the metal plate is laser-welded. 2A is an enlarged plan view in which the metal plate portion of FIG. 1B is overlapped with the laser scanning pattern, and FIG. 2B is an enlarged plan view of the metal plate portion of FIG. 1C. 3 is a cross-sectional view taken along line III-III in FIG. 2B.

  As shown in FIG. 1A, the sealing lid 16 of the rectangular sealed battery according to the embodiment has a substantially rectangular shape, and a negative electrode terminal 18 attached via an insulator 17 is provided at the center. In addition, an electrolyte injection hole 21 is provided at the peripheral edge. The sealing lid 16 is attached in advance to the inner edge of the opening of the outer can 15, and then the joint between the sealing lid 16 and the battery outer can 15 is welded by laser light over the entire circumferential direction. After injecting a predetermined amount of electrolyte with a predetermined composition from the electrolyte injection hole 21 of the sealing lid 16, as shown in FIG. 1B, a rubber plug 30 (see FIG. 3) provided on the surface of the metal plate 29 is used. It is placed and fixed on the surface of the sealing lid 16 by being inserted into the electrolyte injection hole 21. Here, as the shape of the metal plate 29, a rectangular shape with a corner cut off was used.

  Next, the laser head (not shown) is relatively moved along the locus 31 shown in FIG. 2A along the first short side 32 of the metal plate 29 upward in the drawing until slightly passing the corner. Then, move to the position corresponding to the second short side 33 in the right direction, parallel to the long side, and then move downward along the second short side 33 in the same way. . At that time, a series of weld beads is formed by intermittent laser irradiation.

  Thus, as shown in FIG. 2B, the first bead row 34 is formed on the first short side of the metal plate 29, and the irradiation mark 36 for discrimination along the long side. Further, a second bead row 35 is formed on the second short side. The metal plate 29 is firmly welded to the sealing lid 16 by the first bead row 34 and the second bead row 35, and the electrolyte solution injection hole 21 provided in the sealing lid 16 is sealed by the metal plate 29. It is ensured by the rubber plug 30 provided on the surface of the. In addition, since an irradiation mark 36 for determination is formed in the vicinity of the long side of the metal plate 29, the manufacturing history of the sealed battery can be determined by the irradiation mark 36.

  The irradiation mark 36 for discrimination in this embodiment is relatively close to the second short side 33 after the laser head forms the first bead row 34 on the first short side 32 of the metal plate 29. Formed on the way to travel. Therefore, in this embodiment, in particular, it is not necessary to move the laser head in a different direction in order to form the irradiation mark 36, and it is not necessary to weld the entire periphery of the metal plate 29. Compared to such a conventional example, a significant reduction in welding time can be achieved.

[Experimental example]
Hereinafter, the effect of shortening the welding time when the manufacturing method of the sealed battery of the example is adopted will be clarified using specific data. First, the electrolyte injection hole is closed with a rubber stopper provided on the surface of a rectangular metal plate with a 2 × 4 mm corner, and two 2 mm short sides of the metal plate are laser welded to a sealing lid and sealed. When sealing the electrolyte injection hole by fixing the stopcock, the processing head was relatively scanned as follows as an example of not forming an irradiation mark for discrimination.

The processing head is fixed, the battery is placed on the XY table, the speed of the XY table is 20 mm / second (ie, welding speed = 20 mm / second), and the time required for acceleration / deceleration of the XY table is set. Assuming 0.1 second, the time required for scanning the machining head in each section is as shown in Table 1 below, and the total is about 0.8 seconds.

Here, when the irradiation trace for manufacturing history discrimination is added as in the conventional example, the following time is further required.
(1) After moving the machining head, if it is moved so as to form a laser irradiation trace for manufacturing history discrimination at a point about 1 mm away from the end point, 0.1 second each is required for acceleration and deceleration In addition, since it takes about 0.04 seconds for communication until the laser is actually emitted after the processing head is stopped, a further 0.24 seconds are further required.
(2) In the same manner as in the case of (1), if two or more discrimination irradiation traces are to be made, about 0.24 seconds are required for each point.
(3) Although it is possible to discriminate even if the discrimination irradiation trace is formed at the same time as the laser scanning end point, the time required for communication until the laser is emitted requires about 0.04 seconds. In this case, since the irradiation trace is close to the welded portion, it is difficult to distinguish between the welding bead and the irradiation trace for discriminating the processing head, and it is difficult to confirm whether there is an irradiation trace.
(4) The above (1) to (3) are cases in which the discrimination irradiation trace is formed after laser welding, but the same applies if the discrimination irradiation trace is formed before laser welding.

  However, in the case of the above embodiment, the irradiation trace for manufacturing history determination may be irradiated with laser while the processing head is moving relatively in parallel with the long side of 4 mm, so the time required for communication or the like is 0.04. Even if it is about 2 seconds, since the communication is performed during the parallel movement, the processing time is not substantially increased.

  As described above, according to the present invention, it is not necessary to lengthen the time for moving the machining head relatively for laser welding, that is, for the purpose of discriminating manufacturing history without increasing the time required for manufacturing. An excellent effect that a laser irradiation trace can be formed can be obtained. In the above embodiment, the laser welding method is employed as the welding method. However, the present invention is not limited to this, and a well-known high energy beam, for example, an electron beam welding method can also be used.

It is a figure which shows each manufacturing process of the sealed battery which concerns on an Example, FIG. 1A is the state of the sealing lid after electrolyte solution injection, FIG. 1B is the state which plugged the electrolyte solution injection hole with the metal plate, and a figure. 1C is a plan view of a state in which the metal plate of the sealing plug is laser-welded. 2A is an enlarged plan view in which the metal plate portion of FIG. 1B is overlapped with the laser scanning pattern, and FIG. 2B is an enlarged plan view of the metal plate portion of FIG. 1C. It is the III-III sectional view taken on the line of FIG. 2B. It is a perspective view which cut | disconnects the square nonaqueous electrolyte secondary battery of a prior art example to the vertical direction, and shows it. It is a figure which shows the process of laser-welding the sealing lid of the nonaqueous electrolyte secondary battery of a prior art example to the opening part of a square battery exterior can. It is a longitudinal cross-sectional view which shows a mode that the electrolyte solution injection hole of the conventional sealing lid and a metal plate are laser-welded. It is a top view which shows a mode that the electrolyte solution injection hole of the conventional sealing lid and a metal plate are laser-welded.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Nonaqueous electrolyte secondary battery 11 Negative electrode plate 12 Positive electrode plate 13 Separator 14 Spiral electrode body 15 Exterior can 16 Sealing lid 17 Insulator 18 Negative electrode terminal 21 Electrolyte injection hole 26 Seal plug 29 Metal plate 30 Rubber plug 31 Laser head Locus 32 of the metal plate First short side 33 of the metal plate Second short side of the metal plate 34 First bead row 35 Second bead row 36 Irradiation trace for discrimination

Claims (3)

The electrolyte injection hole provided in the battery is closed with a stopper, and at least two portions of the periphery of the metal plate arranged so as to cover the stopper are welded to the sealing lid with high energy rays to seal the electrolyte injection hole. In the manufacturing method of the sealed battery to be stopped,
Forming an irradiation mark for discrimination by the high energy ray while moving the machining head relatively from the welding end point of the first welding point to the welding start point of the second welding point by the high energy ray. A method for producing a sealed battery, which is characterized.   The metal plate that covers the stopper is polygonal, elliptical, or circular, and the first and second welded portions are provided at peripheral edges facing each other. Manufacturing method for a sealed battery.   The method for manufacturing a sealed battery according to claim 1, wherein the high energy beam is formed of a laser beam or an electron beam.

Images