JP2002208380A - Battery and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a battery and its manufacturing method which can achieve a highly reliable sealing through calking process made with the use of a ring- shaped groove formed in a place which does not diminish an inner space of a battery. SOLUTION: After a group of electrodes are contained in a battery case 5 of nearly rectangular shape in cross section, and an opening top 11 of the battery case 5 is compression molded in a cylindrical shape, a groove-making roller 9 is pressed against the side face of the opening top 11 as the battery case 5 is turned, to form a ring-shaped groove 5a. Electrolyte solution is injected in a ring-shaped support part 5b swollen inward after a sealing material 10 is supported, and an opening end of the battery case 5 is bent inward and then, the sealing material 10 is calked and fixed between the opening end and the ring-shaped support part 5b.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sealed battery in which a power generation element such as an electrode group and an electrolyte is sealed in a battery case, and a method for manufacturing the same.

[0002]

2. Description of the Related Art In recent years, with the development of various types of portable electric equipment, development of a battery serving as a driving power source has been regarded as important as one of the important key devices. Among these batteries, small rechargeable batteries such as rechargeable nickel-metal hydride batteries and lithium-ion rechargeable batteries are widely used in mobile phones, notebook computers, video cameras, etc.
In recent years, development has been advanced for use as a drive power source of a hybrid electric vehicle, and the demand has been increasing.

[0003] Such batteries are roughly classified into a cylindrical type and a square type. In the cylindrical battery, an electrode group 4 having a separator 3 interposed between a strip-shaped positive electrode plate 1 and a negative electrode plate 2 is spirally wound and housed in a battery case 5 (see FIG. 2 showing this embodiment). ) Due to the structure, the energy density per unit volume is high. On the other hand, as shown in FIG. 7, a prismatic battery generally has a structure in which an electrode group 4 in which a separator 3 is interposed between a positive electrode plate 1 and a negative electrode plate 2 is stacked and housed in a battery case 5. Comparing this point, the cylindrical battery is excellent in productivity and low in cost. However, in the case where a battery pack is formed by accommodating a plurality of battery packs in a pack case, for example, a cylindrical battery has a wasteful remaining space, that is, a dead space, and thus has poor space efficiency (see FIG. 5 showing a comparative example of this embodiment). In addition, since the stability in the storage space is poor, it is not suitable for miniaturization and thinning of electric equipment.

[0004] On the other hand, prismatic batteries have a high space efficiency and can be stably accommodated in a storage space. However, due to the above-mentioned laminated structure, if the number of laminated electrode plates is increased in order to increase the battery capacity, connection is made. For example, the number of the lines 6 (FIG. 7) increases and the production cost increases. In addition, it has the disadvantage that sealing is difficult and the reliability is inferior to cylindrical batteries.

[0005] As a method of sealing, in a square battery, a method of laser welding a joint between a sealing plate and a case opening is generally used. However, this method increases the manufacturing cost and stabilizes the welding state. It is difficult to control the conditions of the laser to make the laser lighter, and it cannot be said that the method is highly reliable. Further, in a rectangular battery as shown in FIG. 7, a method of closing the sealing body 10 and the opening by a caulking method in the same manner as the cylindrical battery,
It is disclosed in JP-A-63-221551 and the like.
However, according to this method, it is difficult to form an annular groove in the side surface of the battery case for hermetic sealing with the sealing body 10, and further, when the end portion of the rectangular tubular case is swaged, distortion is likely to occur at each corner. Therefore, there is a problem that the sealing performance is lower than in the case where the cylindrical battery is crimped.

Therefore, as shown in FIG.
The opening head 11 of the battery case having a cylindrical shape;
A method of caulking the cylindrical portion is conceivable. As this caulking method, for example, a method of manufacturing a battery using a caulking method (see FIG. 8) disclosed in Japanese Patent Application Laid-Open No. 58-112259 will be described.

After the electrode group is accommodated in the battery case 5, the bottom of the battery case 5 is inserted into the holder 7, and the battery case 5 is pressed from the bottom side in the axial direction with the upper fixing portion 8 To fix the opening of the battery case 5, and then rotate the upper fixing portion 8 at a predetermined rotation speed to
To rotate. In this state, while pressing the battery case 5 from the bottom side in the axial direction, the groove forming roller 9 is pressed against the side surface of the battery case 5 with a predetermined pressure to form the annular groove 5a near the opening. The annular support 5b bulged inward by the formation of the annular groove 5a is inserted into the sealing body 10b.
(FIG. 9), the opening of the battery case 5 is bent inward, and the opening end and the annular support portion 5b are bent.
The inside of the battery is hermetically sealed by caulking and fixing the sealing body 10 in between.

[0008]

However, the method of forming the annular groove used in the above-mentioned conventional example is changed to a method of manufacturing a battery having a square tubular body 12 and a cylindrical opening head 11 as shown in FIG. When used, since the pressing force is applied in the axial direction from the bottom side of the battery case 5, the material is not smoothly supplied to the annular groove 5a from the rectangular cylindrical body 12 side. When the groove 5a is formed at the boundary between the opening head 11 and the body 12, the material is locally extended by the grooving roller 9 with almost no material supply, and the thickness of that portion is thin. This causes problems such as deformation and cutting.

Therefore, when the annular groove 5a is formed by a conventional method of pressing from the bottom side of the battery case 5,
A state in which some cylindrical portions 5c are left under the annular groove 5a for material supply (see FIG.
(See (b))) to form the annular groove 5a,
The inside of the cylindrical portion 5c below the annular groove 5a is a useless space, which causes a problem of loss of the internal space of the battery case 5.

Therefore, the present invention takes advantage of the features of a rectangular battery having a good space efficiency when storing a plurality of batteries, and uses an annular groove formed at a position that does not cause loss of the internal space of the battery case. An object of the present invention is to provide a battery capable of performing highly reliable sealing by processing and a method for manufacturing the battery.

[0011]

In order to achieve the above object, a battery according to the present invention comprises a battery case in which an electrode group and an electrolyte are accommodated in a rectangular cylindrical body, and a cylindrical opening of the battery case. The sealing body is supported by the annular support portion that bulges inward due to the formation of the annular groove on the side surface of the battery case, and the open end of the battery case is bent inward. Wherein the annular groove is located at a boundary between a cylindrical opening head and a rectangular tubular body. Features.

According to this battery, an annular groove is formed in the cylindrical opening head while exhibiting the characteristics of a rectangular battery which has a high space efficiency and can be stably housed in the housing space. The sealing body is caulked and fixed by the same caulking method as that of the cylindrical battery between the annular support bulging inward by the formation and the opening end of the battery case, so that the sealing is easy and the airtightness is improved. Will also be excellent. The annular groove is
Since it is located at the boundary between the cylindrical opening head and the prismatic body that contains the electrode group and the electrolytic solution, loss of the internal space of the battery case is small.

In the above battery, if each corner of the body of the battery case has a substantially square cross-sectional shape in which a predetermined round shape is formed, the case can be easily processed and the cylindrical shape can be obtained. Plastic deformation is easy during the formation of the opening head and the annular groove, and the pressure resistance against an increase in internal pressure during overcharge or overdischarge is excellent. In addition, when a plurality of batteries are housed side by side in a pack case to form a battery pack or when housed in a battery housing of an electric device, damage or dents occur when batteries come into contact with each other. Can be prevented beforehand.

In the above battery, the electrode group may be wound with a separator interposed between the belt-like positive electrode plate and the negative electrode plate to form a cross-sectional shape corresponding to the cross-sectional shape of the body of the battery case. The productivity is improved, and the energy density per unit volume is increased.

In order to achieve the above object, a method of manufacturing a battery according to the present invention is characterized in that a group of electrodes is accommodated in a substantially square battery case having a predetermined rounded portion at each corner.
After compression molding the opening head of the battery case into a cylindrical shape,
While applying a pressing force to the battery case from the opening side in the axial direction, rotate the grooved roller while rotating the battery case.
An annular groove is formed by pressing against the side surface of the opening head from the side, and an annular electrolyte is injected into the annular support portion bulging inward after supporting the sealing body, and the opening end of the battery case is opened. Is bent inward, and the inside of the battery is sealed by caulking and fixing the sealing body between the opening end and the annular support portion.

According to this battery manufacturing method, the annular groove is formed in the cylindrical opening head, and the annular groove is formed between the annular support bulged inward by the formation of the annular groove and the open end of the battery case. In addition, since the sealing body can be caulked and fixed by the same caulking method as the cylindrical battery, the battery that is easily sealed and has excellent sealing performance can be stably housed in the storage space with high space efficiency. It can be manufactured while maintaining the characteristics of the prismatic battery. In addition, since the annular groove is formed while being pressed from the opening side of the battery case, it is possible to supply a sufficient amount of material for forming the annular groove, and to have a substantially uniform thickness and excellent dimensional stability. The formed annular groove can be reliably formed at the boundary between the cylindrical opening head and the rectangular cylindrical body. Therefore, there is no need to leave a cylindrical portion for supplying the material below the boundary as in the conventional example pressed from the bottom side, and the loss of the internal space of the battery case is reduced. In addition, since the electrode group is housed in a substantially square battery case having a predetermined round shape at each corner,
Plastic deformation is facilitated during the formation of the cylindrical opening head or the annular groove, and the pressure resistance against internal pressure rise at the time of overcharge or overdischarge is excellent. In the case where the battery pack is housed to form a battery pack or when housed in the battery housing section of an electric device, it is possible to manufacture a battery that can prevent damages and dents when the batteries come into contact with each other. it can.

It is preferable that the radius of curvature of the rounded portion is set to, for example, 4 to 7 mm.

Further, in the above method, the electrode group is wound into a columnar shape with a separator interposed between a strip-shaped positive electrode plate and a strip-shaped negative electrode plate. After performing compression molding so that
If it is inserted into the battery case in a press-fitted state, the degree of tension is slightly loosened at the time of insertion and it is slightly deformed into a state of swelling due to the restoring force to a circular shape, and a dead space inside the above-mentioned round shape portion By closely contacting the inner surface of the battery case without leaving any, a battery having a high energy density per unit volume can be manufactured with high productivity.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be specifically described below with reference to the drawings. still,
The same parts as those in the conventional example will be described with the same reference numerals. In addition, the present invention is not limited to the following embodiments, and can be implemented with appropriate changes within the scope of the present invention.

FIG. 1 is a perspective view showing a battery according to an embodiment of the present invention, and FIG. 2 is a sectional view taken along the line AA 'of FIG. This battery has a band-shaped positive electrode plate 1 and a negative electrode plate inside a body 12 of a bottomed rectangular cylindrical battery case 5 having a substantially square cross-sectional shape in which each corner is formed in a predetermined round shape. 2 and a group of electrodes 4 wound with a separator 3 interposed therebetween are accommodated, and an electrolyte is injected into the battery case 5.

The opening head 11 of the battery case 5 is formed in a cylindrical shape, and the sealing body 10 is mounted via an insulating gasket 13 on an annular support portion 5b bulging inward by an annular groove 5a formed on the side surface thereof. After being placed and supported, the opening end of the opening head 11 is bent inward, and the sealing body 10 is caulked and fixed between the opening end and the annular support portion 5b, whereby the inside of the battery is sealed. It has become.

The electrode group 4 is formed by spirally winding a strip of the positive electrode plate 1, the negative electrode plate 2, and the separator 3 into a columnar shape, and then performing compression molding with a mold on the battery case. 5, and is inserted into the battery case 5 in a press-fit state. As a result, when the electrode group 4 is inserted into the body portion 12, the electrode group 4 slightly deforms to a state in which the degree of tension is slightly loosened and swells due to a restoring force to the original circular shape, and Against each other.

In this battery, since each corner of the battery case 5 has a predetermined radius shape, for example, a radius-shaped portion 5d having a radius of curvature of 4 to 7 mm, the case processing is facilitated. , Cylindrical opening head 11 and annular groove 5
It is easy to plastically deform when forming a, and has excellent pressure resistance against internal pressure rise during overcharge or overdischarge. Further, even when the electrode group 4 wound in a columnar shape as described above is compression molded and pressed into the battery case 5, no dead space is left. Further, as described later in FIG. 5, when a plurality of batteries are housed side by side in a pack case to form the battery pack 17 or when housed in a battery housing of an electric device, when the batteries come into contact with each other, Problems such as damage and dents can be prevented beforehand.

FIG. 3 is a perspective view showing the manufacturing method of this embodiment in the order of steps. First, as shown in (a), the battery case 5 is formed in the shape of a bottomed rectangular tube having a substantially square cross section and having a rounded portion 5d as described above. After the electrode group 4 is spirally wound in a state where the electrode group 4 is overlapped with the positive electrode plate 1 and the negative electrode plate 2 and the separator 3 interposed therebetween, the cross section corresponding to the cross sectional shape of the battery case 5 is substantially reduced. Compression molding into a square shape. On the upper end surface of this electrode group 4,
The positive electrode current collector 16 is welded, and a positive electrode lead piece 14 projecting upward is welded onto the positive electrode current collector 16. On the lower end surface of the electrode group 4, a negative electrode current collector (FIG. 2) integrated with the negative electrode lead piece 15 is welded downward. The electrode group 4 thus formed is inserted into the battery case 5.

After inserting the electrode group 4 into the battery case 5, a welding electrode rod is inserted from the center hole of the electrode group 4,
The lead piece of the negative electrode current collector 15 is pressed so as to project downward, and is resistance-welded to the bottom surface of the battery case 5.

Next, the battery case 5 is subjected to compression molding by a metal mold at a portion near the opening, and (b)
As shown in (1), a cylindrical opening head 11 is formed, and an insulating gasket 13 is fitted inside the opening head.

Thereafter, as shown in FIG.
The electrode group 4 is fixed in the battery case 5 by forming an annular groove 5a on the side surface of the battery case 5. A method of forming the annular groove 5a will be described with reference to FIG.

First, after the bottom of the battery case 5 is inserted into the holder 7, the upper fixing portion 8 is pressed against the holder 7 with a predetermined pressure to fix the opening head 11 by the upper fixing portion 8, and The battery case 5 is rotated by rotating the holder 7 at the rotation speed. In this state, while the battery case 5 is applied with a predetermined pressing force in the axial direction from the opening side, the groove forming roller 9 is pressed against the side surface of the opening head 11 from the side while rotating the battery case 5. Thereby, an annular groove 5a is formed. Thereafter, a predetermined amount of alkaline electrolyte is injected into the battery case 5 from the center hole of the electrode group 4 shown in FIG. 3C, and then the annular support portion 5b bulged inward by the annular groove 5a.
Next, the sealing body 10 is supported via the insulating gasket 13.

In this state, as shown in FIG. 3D, the opening end of the opening head 11 is bent inward, and the sealing body 10 is caulked and fixed between the opening end and the annular support portion 5b. By doing so, the inside of the battery is sealed to form the battery.

(Embodiment) An embodiment of the present invention will be described in detail below. In this example, a battery was manufactured as follows.

That is, a band-shaped positive electrode plate having a height of 34 mm, a width of 250 mm and a thickness of 0.62 mm containing nickel hydroxide as an active material, and a height of 34 mm, a width of 310 mm and a thickness of 0 containing a hydrogen storage alloy as an active material. An electrode group was formed by winding a band-shaped negative electrode plate having a width of .36 mm with a polypropylene separator subjected to a hydrophilic treatment interposed therebetween, and welding a positive electrode current collector on the upper part and a negative electrode current collector on the lower part.

As the battery case, a metal case made of nickel-plated iron having a thickness of 0.3 mm and a height of 45 mm having a substantially square cross section of 21 mm on a side with each corner formed in a round shape of R6. Using the method described above, a battery was manufactured by the manufacturing process illustrated in FIG. 3 and the method of forming the annular groove illustrated in FIG. Note that the opening head 11 was compression-molded into a cylindrical shape having a diameter of 21 mm up to a portion corresponding to 7 mm in the upper part.

The battery obtained as described above was subjected to initial charge / discharge, and a height of 42 mm, a side of a square having a cross section of 21 mm,
Battery A having a standard capacity of 3600 mAh was manufactured.

COMPARATIVE EXAMPLE 1 A battery pack 17 was prepared by combining a battery A manufactured as described above and a cylindrical battery B having a height of 42 mm, a diameter of 21 mm and a standard capacity of 3000 mAh as a comparative example. The differences in space efficiency in the following are compared.

As an example, FIGS. 5 (a) and (b) show a case where nine batteries A and nine batteries B of the comparative example are stored in the battery pack 17 for a power tool, respectively. Compared with the case of the battery B, the battery pack 17 containing the battery A of the present embodiment exhibits the feature of a rectangular battery that has a small remaining space and excellent space efficiency. In addition, since the battery A of the present example has the rounded portion 5d as shown in the above embodiment, when the battery pack 17 is configured or stored in the battery storage portion of the electric device. In addition, it is possible to prevent problems such as damage and dents when batteries come into contact with each other. In addition, the opening head 11 is formed into a cylindrical shape so that a general cylindrical battery caulking method can be employed, and the method of forming the annular groove 5a for sealing the cylindrical portion is described below. Since the pressing direction is changed in consideration of the shape of the prismatic battery, the productivity is good while the body 12 has the structure of the prismatic battery with the prismatic shape, and the reliability to the sealing portion is high. The characteristics of cylindrical batteries can also be demonstrated.

Hereinafter, the structure of the annular groove portion will be described in comparison with a structure using a conventional annular groove forming method.

(Comparative Example 2) In Comparative Example 2, in order to form an annular groove, pressing was performed from the bottom side of the battery case as shown in FIG. 8 of the conventional example (in the example, as shown in FIG. 4). In the same manner as in the above embodiment, except that the groove-forming roller is pressed against the side surface of the boundary between the opening head and the body in the state of being pressed from the opening side of the battery case. Battery.

As a result, since little material is supplied from the bottom side, the annular groove portion is locally extended by the grooving roller, and a portion thereof is cut off because the thickness is not uniform. Many of them were deformed or deformed, and a stable annular groove could not be formed. For this reason, in order to form an annular groove in a battery having a cylindrical opening head and a square tubular body, FIG. 6B is an enlarged view of a main part taken along line BB ′ of FIG. As described above, the annular groove 5a must be formed with some cylindrical portion 5c left under the annular groove 5a for material supply, but this requires the inside of the cylindrical portion 5c below the annular groove 5a. Is a wasteful space, and there is a problem that the internal space of the battery case 5 is lost. Therefore, in this embodiment, FIG.
As shown in FIG. 5, a sufficient material supply for forming the annular groove 5a can be achieved by pressing from the opening side of the battery case 5, so that the cylindrical opening head 11 and the square tubular body 12, a uniform thickness can be ensured, the annular groove 5a having excellent dimensional stability can be reliably formed, and the loss of the internal space is reduced.

In the above embodiment, a nickel-metal hydride storage battery using a nickel electrode for the positive electrode plate and a hydrogen-absorbing alloy electrode for the negative electrode plate has been described. Similar effects can be obtained for secondary batteries and the like.

[0040]

As described above, according to the present invention, while taking advantage of the characteristics of a square battery having good space efficiency when storing a plurality of batteries, a cylindrical opening head and a square tubular body are utilized. A battery capable of reducing the loss of the internal space of the battery case and achieving highly reliable sealing by caulking using an annular groove formed at a boundary position between the battery case and the manufacturing method thereof can be provided.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a battery according to an embodiment of the present invention.

FIG. 2 is a sectional view taken along line A-A ′ of FIG. 1;

FIG. 3 is an exemplary perspective view showing the manufacturing steps of the embodiment in order;

FIG. 4 is an exemplary sectional view showing the method of forming the annular groove used in the embodiment;

FIG. 5 is a top view comparing the battery of the example of the present invention with a cylindrical battery.

FIG. 6 is an enlarged view of a main part taken along line BB ′ of FIG. 1 to compare the battery of the example with a prismatic battery using a conventional annular groove forming method.

FIG. 7 is a perspective view showing an example of a conventional prismatic battery.

FIG. 8 is a cross-sectional view showing a conventional method of forming an annular groove used for a cylindrical battery.

FIG. 9 is a perspective view showing a prismatic battery using a conventional annular groove forming method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Positive electrode plate 2 Negative electrode plate 3 Separator 4 Electrode group 5 Battery case 5a Annular groove 5b Annular support part 5c Cylindrical part below annular groove (conventional example) 5d R-shaped part 9 Slotting roller 10 Sealing body 11 Opening head 12 Body 13 Insulating gasket 14 Positive electrode lead piece 15 Negative current collector 16 Positive current collector

 ──────────────────────────────────────────────────の Continuing on the front page (72) Inventor Masaharu Miyahisa 1006 Kazuma Kadoma, Osaka Pref.Matsushita Electric Industrial Co., Ltd. F-term (reference) 5H011 AA03 AA09 AA17 CC06 DD03 DD05 DD06 DD15 KK03 5H028 AA01 AA07 BB01 BB03 BB04 BB07 CC07 CC12 HH05 5H029 AJ14 AJ15 AM01 BJ02 BJ14 CJ01 CJ03 CJ06 CJ07 HJ12 DJ02

Claims (6)

[Claims] 1. An electrode group and an electrolytic solution are accommodated in a rectangular cylindrical body of a battery case, and swelled inward by forming an annular groove on a side surface of a cylindrical opening of the battery case. The sealing member was supported by the annular support portion, and the opening end of the battery case was bent inward, and the sealing member was caulked and fixed between the opening end portion and the annular support portion, thereby sealing the battery case. A battery according to claim 1, wherein said annular groove is located at a boundary between a cylindrical opening head and a rectangular tubular body. 2. The battery according to claim 1, wherein the body of the battery case has a substantially square cross section in which each corner is formed in a predetermined round shape. 3. The electrode group is wound with a separator interposed between a strip-shaped positive electrode plate and a negative electrode plate, and formed in a cross-sectional shape corresponding to the cross-sectional shape of the body of the battery case. 3. The battery according to 1 or 2. 4. An electrode group is accommodated in a substantially square battery case having a predetermined rounded portion at each corner, and the opening of the battery case is compression-molded into a cylindrical shape. While applying a pressing force in the axial direction from the opening side to the battery case, the grooved roller is pressed from the side against the side surface of the opening head while rotating the battery case to form an annular groove. After the sealing body is supported on the inwardly swelling annular support portion, the electrolytic solution is injected, and the open end of the battery case is bent inward. A method for producing a battery, comprising sealing the inside of a battery by caulking and fixing a sealing body. 5. The method for manufacturing a battery according to claim 4, wherein the radius of curvature of the radius-shaped portion is 4 to 7 mm. 6. The electrode group is wound into a column shape with a separator interposed between a strip-shaped positive electrode plate and a negative electrode plate so that the electrode group has a cross-sectional shape corresponding to the cross-sectional shape of the battery case. 6. The method for producing a battery according to claim 4, wherein the battery is subjected to compression molding and then inserted into the battery case in a press-fit state.