JP2006100213A - Manufacturing method of square battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of a square battery allowing a protective tape to be efficiently arranged in an electrode body composed by stacking positive and negative electrode plates by interlaying a separator. <P>SOLUTION: An insulating protective tape material 251 formed of polypropylene or the like is paid out from a roll 5; its end 252 is held by a chuck 8; and it is stretched. The electrode body 20 is faced to an exterior can 30 by interlaying the protective tape material 251 in this state; and the electrode body 20 is depressed into the exterior can 30 along with the protective tape material 251 and housed in the exterior can 30. A redundant part of the protective tape material is cut by a heat cutter 10. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for manufacturing a rectangular battery.

  In recent years, portable electronic devices such as mobile phones and personal digital assistants (PDAs) are rapidly spreading. In these electronic devices, a battery having a rectangular outer can such as a nickel metal hydride battery or a lithium ion battery is frequently used as a high energy density power source. Since the square battery can use space more effectively than the cylindrical battery, it is advantageous for the demand for downsizing and space saving in the electronic device.

A prismatic battery generally contains a power generating element containing an electrolyte in a rectangular outer can. For example, the power generating element is obtained by impregnating an electrolytic solution in a rectangular parallelepiped electrode body in which strip-shaped separators, a positive electrode, and a negative electrode are stacked. The volume of the electrode body is increased close to the volume of the outer can in order to obtain a high energy density of the battery.
In the method for manufacturing a battery having a rectangular outer can having the above-described configuration, as an example, the electrode body is first housed in an outer can made of a nickel-plated steel plate. Thereafter, a sealing body is attached to the opening of the outer can, and the boundary between the outer can and the sealing body is laser-welded. Then, a necessary amount of electrolyte is injected through an injection port provided in the sealing body, the injection port is closed with a sealing plug, and the inside of the battery is sealed.

Here, when the electrode body is inserted into the outer can, the lower part of the electrode body located on the outermost surface is in contact with the periphery of the outer can opening due to a slight misalignment between the outer can and the electrode body. There is. And the problem that the active material currently apply | coated to the electrode part which contacted the exterior can side is scraped by such contact arises.
When the active material scraped off in this way adheres to the opening of the outer can, the sealing performance of the sealing body during laser welding at the time of manufacture is deteriorated, causing the electrolyte to leak. Moreover, if the active material falls into the outer can, it may cause an unnecessary short circuit later, which is not preferable.

As a measure to solve such a problem, an insulating protective tape is attached to the electrode body portion (that is, the lower portion of the electrode body) that is first inserted into the outer can, and the electrode body contacts the outer can side. A technique for preventing the peeling of the active material has been devised.
Japanese Utility Model Publication No. 6-54208 JP-A-10-208769 Japanese Patent No. 3359498

However, according to the conventional manufacturing method using the protective tape, the protective tape is provided at a predetermined position with respect to the electrode body, and thus a step of attaching the protective tape cut to a certain length to each electrode body is required. And There is a problem that the production efficiency of the prismatic battery is reduced by the increase in the sticking step.
In addition, the electrode body is formed in the same size as the outer can for the purpose of increasing the capacity density of the battery, and in order to facilitate insertion into the outer can, the electrode body is pressurized and attached to the electrode body. In some cases, the thickness of the protective tape is reduced. However, the protective tape attached to the electrode body in this way is difficult to maintain its form for a long time. This is because the protective tape loses the expansion force of the electrode body over a long period of time, and the electrode body tends to return to its original size, which may make the insertion difficult.

  Therefore, after attaching the protective tape to the electrode body, it must be immediately stored in the outer can. However, if it is left for a relatively long period of time due to production control or a production line failure, it must be applied to the electrode body. The worn protective tape may be extended. When the protective tape extends in this manner, it becomes difficult to store the protective member in the outer can, and a manufacturing defect that prevents the electrode body from being stored well may occur. In particular, this manufacturing defect tends to become more prominent as the size of the rectangular battery is thinner.

From the above, problems to be solved still remain for the method of manufacturing a rectangular battery.
This invention is made | formed in view of the said subject, Comprising: It aims at providing the manufacturing method of the square battery which enables arrangement | positioning of an efficient protective tape, and insertion of an electrode body.

  In order to solve the above-mentioned problems, the present invention provides a method for manufacturing a prismatic battery that includes an electrode body housing step of housing an electrode body in which positive and negative electrode plates are stacked via a separator in an outer can. In the step, the electrode body was pressed against the stretched protective tape, the electrode body was guided to the outer can opening while the protective tape was deformed, and the electrode body and the protective tape were inserted into the outer can.

  Here, in the electrode body storing step, a roll-shaped protective tape is drawn out and a part thereof is stretched, and the electrode body and the protective tape are inserted into the outer can, and the excess of the protective tape can be cut.

  In the manufacturing method of the present invention, before the electrode body is stored in the outer can, the electrode body is inserted into the outer can through a protective tape stretched in advance. As a result, even if the protective tape is not attached to the electrode body, it is deformed into a U-shape covering both the main surface and the lower part of the electrode body, so that the protective tape is separately attached to the electrode body as in the past. There is no need for a step to wear. In the present invention, since the protective tape is stretched in advance, the tension of the protective tape acts when the electrode body is inserted, and the lower part of the electrode body is placed inside the electrode body in accordance with the U-shaped deformation. Inward stress is generated along. By such each action, the shape of the tip of the electrode body is adjusted, so that it can be quickly stored in the outer can.

  Furthermore, according to the present invention, since the electrode body is in contact with the protective tape only immediately before storage in the outer can, there is no process of sticking the protective tape to the electrode body for a long period of time, unnecessary extension of the protective tape, etc. The problem can be avoided.

<Embodiment 1>
1. FIG. 1 is a partially cutaway view showing a main configuration of a lithium manganese battery which is an application example of the prismatic battery of the present invention. The configuration shown in this figure is only an example, and the present invention is not limited to this configuration.

As shown in the figure, the lithium manganese battery 1 (hereinafter simply referred to as the battery 1) is mainly composed of the sealing body 10, the electrode body 20, and the rectangular outer can 30 (hereinafter simply referred to as the outer can 30). Here, as an example, the battery 1 is manufactured in a size of 32 mm (z direction) × 31 mm (y direction) × depth (x direction) 9 mm.
The outer can 30 is a bottomed can rectangular casing formed by drawing a nickel-plated steel sheet. The electrode body 20 is housed inside, and the opening 301 is sealed with a peripheral portion 105 of the sealing body 10 described later by laser welding.

The sealing body 10 is mainly composed of a sealing plate 104 formed by punching a nickel-plated steel plate, and has a configuration in which a polypropylene insulating plate 103 is arranged on the main surface inside the battery and a positive electrode terminal 101 is arranged at the center of the main surface outside the battery. Have. The peripheral edge 105 is secured around the sealing plate 104.
The insulating plate 103 prevents the electrode body 20 from vibrating inside the outer can 30.

The main surface centers of the sealing plate 104 and the insulating plate 103 are perforated, and a hollow positive electrode rivet 106 is caulked and fixed thereto via a gasket 102. The positive rivet 106 is connected to the positive electrode plate 204 of the electrode body 20 with a conductive tab (not shown) on the inner side of the outer can 30. The hollow part of the positive electrode rivet 106 serves as an electrolyte injection port.
On the upper surface (battery outer surface side) of the sealing plate 104, a resin sealing plug 107 is disposed so as to cover the hollow portion of the positive electrode rivet 106, and the periphery of the positive electrode rivet 106 is welded to the positive electrode terminal 101. This prevents the electrolyte inside the battery from leaking out. The lower surface (battery inner surface side) of the sealing plate 104 is connected to the negative electrode plate 203 of the electrode body 20 with a conductive tab (not shown).

The electrode body 20 is formed by sequentially laminating a strip-like positive electrode plate 204, a separator 202, a negative electrode plate 203, and a separator 202, respectively. In order to increase the energy density of the battery 1 as much as possible, it is desirable to secure the volume of the electrode body 20 close to the volume of the outer can 30.
The electrode body 20 is impregnated with an electrolytic solution (here, a nonaqueous electrolytic solution) inside the battery 1.

The positive electrode plate 204 is formed by applying a positive electrode mixture in which a conductive agent and a binder are mixed, mainly composed of manganese dioxide as a positive electrode active material, to the surface of a positive electrode core body such as stainless steel. The positive electrode plate 204 is electrically connected to the positive electrode terminal 101 through a conductive tab (not shown) inside the outer can 30.
The negative electrode plate 203 is formed by punching a lithium metal material.

  The separator 202 is a polypropylene non-woven fabric, and is used for insulation between the positive electrode plate 204 and the negative electrode plate 203. The heat resistant temperature is set to about 120 ° C. In FIG. 1, for convenience, the separator 202 is illustrated as a strip having substantially the same size as the positive and negative plates 203 and 204. In practice, the separator 202 is formed into a bag shape and the positive plate 204 is placed in the bag. Insulation with the negative electrode plate 203 is intended.

  Here, a protective tape 250 is provided on the surface of the negative electrode plate 203 or the like corresponding to both surfaces of the rectangular parallelepiped electrode body 20 so as to cover them in a U-shaped cross section through the lower part of the electrode body 20. This protective tape 250 is formed by processing a film material or non-woven fabric made of an insulating material such as polypropylene according to the width of the electrode body 20, and protects the surface of the electrode body 20 against the inside of the outer can 30. Have a role to do. That is, in the battery manufacturing step, the lower part of the electrode body 20 is in contact with the outer can opening 301 or the like, and the active material of the electrode (in this case, the positive electrode plate 203) located on the outermost surface of the electrode body 20 is missing. It is provided to prevent this.

  The size of the protective tape 250 may be at least as long as it covers at least the lower part of the electrode body 20 and the surface of the electrode plate in the vicinity thereof (in this case, the negative electrode plate 203), but as shown in FIG. Providing the outer electrode plate so as to substantially cover the entire surface of the outer surface is more preferable because it can effectively prevent the problem of contact between the electrode plate and the outer can 30. As a material for the protective tape, various insulating materials resistant to the electrolytic solution can be used.

  The feature of the present invention lies in the step of storing the electrode body 20 in the outer can 30 including the method of disposing the protective tape 250 (electrode body storing step). In the present invention, prior to the electrode body storing step as in the prior art, the step of attaching the protective tape 250 previously cut to a predetermined size to the electrode body 20 is not required. For this reason, while preventing the quality change of the protective tape 250 resulting from the electrode body 20, the effect of improving the manufacturing efficiency of a battery can be anticipated.

Hereinafter, this feature will be described together with an overall battery manufacturing method.

2. Manufacturing method of prismatic battery (1) Production of positive electrode plate Manganese dioxide as an active material, carbon black as a conductive agent, and fluororesin as a binder of both are mixed at a mass ratio of 85: 10: 5. And a positive electrode mixture is obtained. This positive electrode mixture is applied to both surfaces of a roll-shaped conductive core made of punching metal (made of stainless steel) and dried at 250 ° C. Then, this is cut into a predetermined size (for example, width 29 mm × height 22 mm × thickness 2.6 mm). Thereby, the positive electrode plate 204 is completed. A plurality of the positive plates 204 are produced, and a part of the active material on the surface of each positive plate 204 is peeled off to dispose conductive tabs.

(2) Step of producing negative electrode plate A strip-shaped negative electrode plate 203 (width 26 mm × height 19 mm × thickness 1.0 mm) made of lithium metal is produced by rolling and punching. A plurality of the negative electrode plates 203 are produced, and a nickel conductive tab is disposed on each negative electrode plate 203.

(3) Electrode Body Production Step Each of the produced positive electrode plates 204 is encapsulated with a bag-like separator 202 (thickness: 0.1 mm) made of a nonwoven fabric mainly composed of polypropylene, and this and the negative electrode plates 203 are alternately arranged. The electrode body 20 was manufactured as a laminate in which the negative electrode plate 203 was positioned on the outermost surface and two positive electrode plates 204 were disposed between the three negative electrode plates. Thereafter, the conductive tabs of each polarity were welded together.

(4) Electrode body accommodation step FIG. 2 is a schematic view showing an electrode body accommodation step. 2A to 2C, 5 is a roll formed by winding a protective tape material, 251 is a protective tape material fed out of the roll 5, 252 is an end of the protective tape material 251, 6 and Reference numeral 7 denotes a roller for guiding the protective tape material 251, and 8 denotes a clamp chuck (jig) supported by an extendable arm. Reference numeral 9 denotes an insertion jig for storing the electrode body 20 in the outer can 30.

  First, as shown in FIG. 2A, a protective tape material 251 (polyethylene terephthalate film) having a width of 30 mm and a thickness of 50 μm is fed out while being guided from the roller 5 to the peripheral surfaces of the guide rollers 6 and 7. Then, the end portion 252 of the protective tape material 251 is gripped by the chuck 8. Here, the step of stretching the protective tape material 251 is performed by urging the chuck 8 so as to pull the end portion 252 downstream. In this state, the outer can 30 (width 31 mm × height 31 mm × thickness 9 mm, material: nickel-plated steel plate / thickness 0.25 mm) and the electrode body 20 are arranged to face each other through the protective tape material 251 (in this case, in the vertical direction) And a predetermined arrangement step is performed. The outer can 30 is disposed such that the opening 301 faces the electrode body 20.

When the arrangement step is completed, the insertion jig 9 is then used to push the electrode body 20 toward the opening 301 (that is, in the vertical direction) of the outer can 30 with the protective tape material 251 interposed therebetween. Thereby, the electrode body 20 is pressed against the surface of the protective tape material 251 as shown in FIG.
Here, immediately after the arrangement step, the protective tape material is not in contact with the electrode body 20 and is not attached to the electrode body 20 as in the prior art. For this reason, the effort concerning the said sticking step can be saved significantly.

The tension when the protective tape material 251 is stretched is preferably 2 to 4N, and in this example, 3N.
Next, the electrode body 20 is deformed so that the lower portion of the electrode body 20 comes into contact with the protective tape material 251 and is bent into a U-shaped cross section so that the protective tape 250 wraps a part of the electrode body 20. Thus, the electrode body 20 is pressurized inward. For this reason, the lower part of the electrode body 20 is maintained in a good shape, and is easily guided to the opening 301 of the outer can 30, so that the effect of being stored smoothly is achieved.

  Thereafter, the electrode body 20 continues to be pressed by the insertion jig 9 and is inserted into the outer can 30 together with the protective tape material 251 (insertion step). Thereafter, when the electrode body 20 is accommodated to some extent, the excess protective tape material 251 is cut by the heat cutter 10. Thus, the protective tape 250 is formed from the long protective tape 251, and the electrode body 20 is completely accommodated inside the outer can 30 together with the protective tape 250 (FIG. 2C).

Thus, according to the electrode body accommodation step of the present invention, before the electrode body accommodation step of housing the electrode body 20 in the outer can 30, a step for separately attaching a protective tape to the electrode body 20, and adhesion This eliminates the need for an adhesive, and can greatly reduce the labor and cost of this sticking step.
Furthermore, in the present invention, a method of inserting the electrode body 20 into the outer can 30 through the preliminarily stretched protective tape material 251 is adopted, so that the protective tape 251 is not in contact with the electrode body 20 until this point. Therefore, problems such as unnecessary extension of the protective tape 250 by the electrode body 20 can be avoided.

Further, according to this method, since the lower part of the electrode body 20 is held by the protective tape 251 covered in a U shape, the insertion jig 9 is pressed from the disposing step to the inserting step. Each step can be performed at once. Also in this respect, since the present invention can perform work quickly, an improvement in manufacturing efficiency can be expected.

After the electrode body storing step is completed as described above, the sealing body 10 and the negative electrode conductive tab are welded, and the positive electrode conductive tab is welded to the positive electrode rivet.

Then, after pouring a predetermined electrolyte into the outer can 30, the peripheral portion 105 of the sealing body 10 and the outer can opening 301 are welded by laser, and the inside of the outer can 30 is sealed, whereby the battery 1 is completed. To do.
In addition, in the present invention, in addition to the process of the electrode body storage step described above, for example, before placing the electrode body and the outer can opposite to each other, a tension is applied by pressing the electrode body on the surface of the stretched protective tape material, In this state, the outer can and the electrode body may be arranged opposite to each other and inserted into the outer can.

3. Production of Examples The battery produced as described above was designated as Example Battery A.
And the battery which attached the protective tape beforehand before the electrode body accommodation step and was produced was made into the comparative example battery B, and the battery without a protective tape was made into the comparative example battery C.
The following experiments were performed on these batteries A, B, and C, and each performance was considered.

3-1. Liquid Leakage Test Each battery A, B, and C was subjected to a thermal shock test (after being left at −30 ° C. for 2 hours and then left at 70 ° C. for 2 hours for 30 cycles), and the subsequent liquid leakage rate was investigated. The results are shown in Table 1 below.

表１に示すように、保護テープを用いた実施例電池Ａおよび比較例電池Ｂでは、封口時のレーザー溶接不良による漏液が発生しないことがわかった。これは、保護テープの使用により極板の活物質が外装缶開口部に付着せず、良好にレーザー封口がなされたものと考えられる。

As shown in Table 1, in Example Battery A and Comparative Example Battery B using a protective tape, it was found that no leakage occurred due to poor laser welding during sealing. This is probably because the active material of the electrode plate did not adhere to the outer can opening due to the use of the protective tape, and the laser sealing was performed well.

3-2. Insertion test Next, in the battery of Comparative Example B, the protective tape was applied to the electrode body, while the Example battery A was left as an electrode body, each electrode body was left for 24 hours, and then stored in an outer can by each method. did. And the ratio (insertion rate) which was able to accommodate the exterior can appropriately was confirmed visually.
The results are shown in Table 2.

この表２に示されるように、実施例電池Ａは、挿入時に保護テープの張力により電極体下部の広がりが抑制されるので、良好に外装缶に収納できた。
これに対し、比較例電池５では外装缶収納前に保護テープを貼着したため、貼着後の放置間で電極体の下部が広がってしまうものが発生し、その分、挿入率が低下した。

As shown in Table 2, Example Battery A was able to be satisfactorily accommodated in the outer can because the expansion of the lower part of the electrode body was suppressed by the tension of the protective tape at the time of insertion.
On the other hand, in the comparative battery 5, since the protective tape was pasted before housing the outer can, there was a case where the lower part of the electrode body spread during the standing after the pasting, and the insertion rate was reduced accordingly.

From the results based on such experiments, the effectiveness of the present invention was confirmed.

<Other matters>
In the above embodiment, the example in which the present invention is applied to the lithium manganese battery has been described. However, the type of the battery is naturally not limited to this, and the present invention is applied to various batteries such as a lithium ion battery and a nickel metal hydride battery. May be.

Further, in the above embodiment, the example of the step of inserting the electrode body by moving it to the outer can side through the protective tape material has been shown, but the present invention is not limited to this, and the electrode body and the outer can are relative to each other. The electrode body storing step may be performed by moving the electrode body. Therefore, the electrode body may be disposed below and the outer can may be disposed above.
Alternatively, for example, the electrode body may be inserted into the exterior can by moving the exterior can side with respect to the electrode body. In this case, the electrode body comes into contact with the protective tape material stretched around the outer can opening, and is thereby easily guided into the outer can. However, in order to obtain the effect of the present invention more satisfactorily, as shown in FIG. 2, the electrode body side is moved and stored with respect to the outer can while using a protective tape stretched widely in the longitudinal direction. Is desirable.

Furthermore, in the above embodiment, the configuration of the electrode body formed by laminating strip (stack) electrodes and separators has been described. However, the present invention is a winding formed by winding a belt-like positive and negative electrode plate through a separator. Even when applied to an electrode body having a revolving structure, it is possible to desire a certain effect.
In the first embodiment, an example in which the width of the protective tape is substantially the same as the electrode plate width of the electrode body is shown. In the present invention, as shown in FIG. It is also possible to use a wider protective tape. It is desirable to use such a wide protective tape because a protective effect can be obtained not only on both main surface portions of the electrode body but also on the side portions thereof.

Furthermore, in the first embodiment, the tape material width direction and the electrode body width direction are made to coincide with each other and inserted into the outer can (see FIG. 2), but in the present invention, it is shown in FIG. 3 (b). As a variation, the angle of the electrode body may be rotated by 90 degrees from this method, and the longitudinal direction of the tape material and the width direction of the electrode body may be aligned. Except for the arrangement relationship, the setting is made in the same manner as described above, and the electrode body is accommodated in the outer can. This method is preferable because it can be inserted into the outer can while protecting both main surface portions and side portions of the electrode body as described above. However, in this method, since the pressing force is relatively weak inside the electrode body in the stacking direction, care must be taken in this respect.
Moreover, in the said embodiment, although the manufacturing method using a roll was shown, it is not limited to the said roll for protective tape material, Even if it stretches and uses the protective tape cut | disconnected to predetermined length, it is the same The effect of.

  The method for manufacturing a prismatic battery of the present invention can be applied to a method for manufacturing, for example, a prismatic lithium ion battery for a general power source.

It is a set figure of the square battery which is one example of application of the present invention. It is a schematic diagram of the electrode body accommodation step of this invention. It is a figure which shows the variation of this invention.

Explanation of symbols

1 Square battery 5 Roll 6, 7 Guide roller 8 Chuck (jig)
9 Inserting jig 10 Sealing body 20 Electrode body 30 Exterior can 202 Separator 203 Negative electrode 204 Positive electrode 250 Protective tape 251 Protective tape material 252 End 301 Opening

Claims (2)

A method for producing a prismatic battery that undergoes an electrode body housing step of housing an electrode body in which positive and negative electrode plates are stacked via a separator, in an outer can,
In the electrode body storing step,
An electrode body is pressed onto a stretched protective tape, the electrode body is guided to the outer can opening while the protective tape is deformed, and the electrode body and the protective tape are inserted into the outer can. Production method. In the electrode body storing step,
Roll out the protective tape and stretch a part of it.
The method for manufacturing a prismatic battery according to claim 1, wherein the electrode body and the protective tape are inserted into an outer can and the excess of the protective tape is cut.

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