JP2006012702A - Manufacturing method of sealed battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of a sealed battery with weight saving and space saving. <P>SOLUTION: A wound-round group 6 winding round a positive and a negative electrode plates is housed in a square battery can 7. A joggling part 15 is formed with a joggling supporter and a joggling roller on a battery can wall above the wound-round group 6. The joggling part 15 is wedge-shaped at cross section with one side at the top nearly at right angles with the battery can wall, and with a slanted side at the bottom nearly at 120° with the battery can wall. A caulking pretreatment part 16 is formed by having the battery can wall above the joggling part 15 bent outside with a caulking pretreatment concave die and a caulking pretreatment convex die. A battery lid 10 is made supported to the joggling part 15, and the caulking pretreatment part 16 and a peripheral part of the battery lid 10 are caulked and sealed to complete a lithium ion battery 20. The joggling part 15 is formed without the battery can 7 distorted, doing away with unnecessary support members. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for manufacturing a sealed battery, and more particularly, to a method for manufacturing a sealed battery in which a battery lid is caulked and fixed to an opening of a bottomed battery can in which an electrode group is accommodated.

  Conventionally, sealed batteries have been widely used in household electrical appliances, and recently, lithium secondary batteries have been used in many portable terminal devices and the like. As a sealing method for a sealed battery, when the battery container is made of metal, a caulking sealing method is often used to simplify the process and reduce the cost, and other methods such as laser welding and electron beam welding are also used. It is used. The shape of such a sealed battery is roughly classified into a cylindrical type and a square type. For cylindrical batteries, the caulking and sealing method is the mainstream, but when the outer diameter of the battery can increases, the battery can of the same thickness is easily deformed by an external force, so the laser welding method is also used for large cylindrical batteries. . On the other hand, in a square battery, a laser welding method is mainly used because the flat surface of the peripheral surface is easily deformed by an external force and it is difficult to crimp and seal the corner and the flat portion.

  However, in the laser welding method, since the complexity of the welding process, the increase in the number of parts for insulation, and the cost increase due to the welding itself are problems, the use of the caulking and sealing method for a rectangular battery has been studied. For example, a technique is disclosed in which a bridging plate is fixed by welding between opposing planes of a battery can peripheral surface, and a battery can wall is supported by the bridging plate to form a protruding portion projecting inward on the battery can wall. (See Patent Document 1). Also, a first step of bending the battery can wall inward to a substantially right angle using a battery lid with a peripheral portion bent in an L shape, and then bending to 90 degrees or more and 180 degrees or less to form an L-shaped battery lid A technique for sealing in a second step of caulking and sealing a battery can wall is disclosed (see, for example, Patent Document 2).

JP-A-8-195203 JP-A-8-195189

  However, in the technique of Patent Document 1 described above, since the cross-linked plate is welded, there are problems such as an increase in weight due to an increase in the number of members and a complicated welding process. In addition, since a space for disposing the cross-linking plate inside the battery is required and the cross-linking plate is welded to the battery can, when the battery can is used as an external terminal of the positive electrode or the negative electrode, the cross-linking plate is used. There is also a problem that a space for insulating from the other electrode inside the battery is further required and the battery volume is increased. Furthermore, in the technique of Patent Document 2 described above, the sealing can be secured with respect to the battery lid whose peripheral portion is bent in an L shape, but for other battery lids, like the L-shaped tip portion. However, since there is no portion serving as a fulcrum for bending the battery can wall, there is a problem that it cannot be hermetically sealed.

  In view of the above-described case, an object of the present invention is to provide a method for manufacturing a sealed battery that can achieve weight reduction and space saving.

  In order to solve the above problems, the present invention provides a method for manufacturing a sealed battery in which a battery lid is caulked and fixed to an opening of a bottomed battery can in which an electrode group is accommodated, and the battery can is sealed. After accommodating the electrode group in the can, a contact tool is brought into contact with the inside of the battery can wall above the electrode group, and the pressure contact tool is pressed from the outside of the battery can wall so that the cross section is wedge-shaped and the one side is the battery. A protruding portion that is substantially perpendicular to the can wall is formed, and the battery lid is supported on one side of the protruding portion, and the battery can wall above the protruding portion and the peripheral portion of the battery lid are caulked and fixed. Including the steps.

  In the present invention, after accommodating the electrode group in the battery can, the abutment tool is brought into contact with the inside of the battery can wall above the electrode group, and the pressure contact tool is pressed from outside to form the projecting portion. The battery can can be prevented from being distorted at the time of forming, and the formed protrusion has a wedge-shaped cross section and one side thereof is substantially perpendicular to the battery can wall so that the battery lid can be supported. The arrangement of a member for supporting the battery lid is not required and the weight can be reduced, and the battery can wall above the projecting portion and the peripheral portion of the battery lid are caulked and fixed, thereby saving space. Can do.

  In this case, if the outer angle formed by the hypotenuse of the wedge-shaped projecting portion and the battery can wall below the projecting portion is an obtuse angle, the projecting portion is projected along with the press-contact of the press fitting having an obtuse angle when the projecting portion is formed. Since the battery can wall below the portion is deformed in an oblique direction toward the tip of the protruding portion, it is possible to suppress the thinning of the protruding portion. Further, the peripheral surface of the battery can may be constituted by a curved surface and a flat surface. Furthermore, before the step of caulking and fixing the battery lid, the concave jig is brought into contact with the outside of the battery can wall above the protruding portion, and the convex jig is pressed from the inside to bend the battery can wall outward. If the step of performing the pre-caulking process is included, the curved battery can wall is bent inward with the curved shape, so that it is caulked and fixed along the shape of the periphery of the battery lid. A caulking shape can be obtained and sealing performance can be improved.

  According to the present invention, after the electrode group is housed in the battery can, the contact tool is brought into contact with the inside of the battery can wall above the electrode group, and the pressure contact tool is pressed from the outside to form the protruding portion. The battery can can be prevented from being distorted at the time of forming the mounting portion, and the formed protruding portion has a wedge-shaped cross section and one side thereof is substantially perpendicular to the battery can wall so that the battery lid can be supported. It is not necessary to place a member to support the battery cover inside, and the weight can be reduced, and the battery can wall above the projecting part and the peripheral part of the battery cover are fixed by caulking so that space saving is achieved. The effect that it can plan can be acquired.

  Hereinafter, an embodiment in which a manufacturing method of the present invention is applied to a prismatic lithium ion battery will be described with reference to the drawings.

<Preparation of positive and negative electrode plates>
In the production of the positive electrode plate, a lithium manganese complex oxide powder as a positive electrode active material, a flaky graphite as a conductive material, and a polyvinylidene fluoride as a binder (hereinafter abbreviated as PVDF) in a weight ratio of 85:10. The mixture was mixed with 5 and the slurry N-methylpyrrolidone (hereinafter abbreviated as NMP) added thereto and kneaded was applied to both sides of an aluminum foil having a thickness of 20 μm. At this time, an uncoated portion was left on the side edge on one side in the longitudinal direction of the aluminum foil. Thereafter, drying, pressing, and cutting were performed to obtain a positive electrode plate having a thickness of 170 μm. The uncoated portion left on the side edge was cut out in a comb shape to form a positive electrode lead piece.

  On the other hand, in the production of the negative electrode plate, 10 parts by mass of PVDF as a binder is added to 90 parts by mass of the amorphous carbon powder of the negative electrode active material, and the slurry obtained by adding and kneading the dispersion solvent NMP is thickened. It apply | coated on both surfaces of 10-micrometer-thick electrolytic copper foil. At this time, an uncoated portion was left on the side edge on one side in the longitudinal direction of the electrolytic copper foil. Then, the 130-micrometer-thick negative electrode plate was obtained by drying, pressing, and cutting. A negative electrode lead piece was formed in the same manner as the positive electrode plate on the uncoated portion left on the side edge.

<Battery assembly>
As shown in FIG. 1, the prepared positive and negative electrodes were wound together with a polyethylene separator having a thickness of 40 μm so that these bipolar plates were not in direct contact with each other, thereby producing a wound group 6. At the winding center, a hollow flat shaft core 1 made of polypropylene was used. At this time, the positive electrode lead piece 2 and the negative electrode lead piece 3 were respectively positioned on opposite sides of the wound group 6. The lower end portion of the flat positive electrode current collecting ring 4 was fixed to the upper end portion of the shaft core 1. The positive electrode lead piece 2 is deformed, and all of the positive electrode lead piece 2 is gathered and brought into contact with the vicinity of the buttocks circumferential surface integrally projecting from the periphery of the positive electrode current collecting ring 4, and then the positive electrode lead piece 2 and the buttocks circumferential surface are ultrasonically welded. Then, the positive electrode lead piece 2 was connected to the collar surface. One end of a positive electrode lead 9 formed by previously superposing a plurality of aluminum ribbons on the upper portion of the positive electrode current collecting ring 4 was welded. On the other hand, the connecting operation between the flat negative electrode current collecting ring 5 and the negative electrode lead piece 3 was performed in the same manner as the connecting operation between the positive electrode current collecting ring 4 and the positive electrode lead piece 2. Thereafter, an insulation coating was applied to the entire circumference of the collar peripheral surface of the positive electrode current collecting ring 4, and the wound group 6 was inserted into a bottomed prismatic battery can 7 made of steel plated with nickel. The battery can 7 used had a length of 108 mm, a width of 34 mm, and a height of 117 mm, and a corner portion of the peripheral surface formed in an R shape. For this reason, the peripheral surface of the battery can 7 is comprised by the curved surface and the plane. A negative electrode lead plate 8 for electrical continuity is welded to the negative electrode current collecting ring 5 in advance, and after the winding group 6 is inserted into the battery can 7, the bottom of the battery can 7 and the negative electrode lead plate 8 are welded. did.

(Stepped portion formation)
As shown in FIG. 2, a battery can is formed by using a step support 21 and a step roller 22 on a can wall (hereinafter simply referred to as a battery can wall) of a battery can 7 above the wound group 6. A stepped portion 15 having a wall protruding inward was formed as follows. That is, the stepped support 21 that is supported by a support column (not shown) disposed outside the battery can 7 is applied to the inside of the battery can 7 with the opening being upward and the vertical direction of the battery can 7 being pressurized. Contacted and fixed (positioned) at that position. Thereafter, the stepping roller 22 was gradually pushed from the outside of the battery can 7 to project the battery can wall inward. The used stepping roller 22 has a cylindrical roller portion, and a pressure contact portion having a substantially square cross section is projected from the outer peripheral surface of the roller portion. The pressure contact portion has a gradient of one side above the tip portion of about 0 degrees and a gradient of the lower hypotenuse of about 30 degrees with respect to the direction perpendicular to the axial direction of the roller portion (lateral direction in FIG. 2). Is set. For this reason, the external angle between the hypotenuse of the press contact portion and the outer peripheral surface of the roller portion below the press contact portion forms an obtuse angle of about 120 degrees. The step support 21 has a square cylindrical support, and a wedge-shaped protrusion is formed on the outer side of the lower end of the support so as to face the oblique side of the pressure contact portion of the step roller 22. . For this reason, the stepped portion 15 is formed in a wedge shape in cross section, the upper side is substantially perpendicular to the battery can wall, and the outer angle α of the stepped portion 15 formed by the lower oblique side and the battery can wall is about 120. It is formed at a degree (obtuse angle).

(Caulking pretreatment)
As shown in FIG. 3, a pre-caulking process was performed on the battery can wall above the stepped portion 15 by using a caulking pretreatment concave mold 31 and a caulking pretreatment convex mold 32 to form a caulking pretreatment section 16. That is, the caulking pretreatment concave mold 25 supported by a column (not shown) disposed outside the battery can 7 is brought into contact with the outside of the battery can wall, and the caulking pretreatment convex mold 26 is pressed from the inside of the battery can 7. The battery can wall was curved. The caulking pretreatment concave mold 25 used has a rectangular tube shape, and a concave portion is formed on the inner peripheral surface of the lower portion. The caulking pretreatment convex mold 26 corresponds to the concave portion of the caulking pretreatment concave mold 25 at the lower end portion of the columnar support. The convex part to be formed is formed. At this time, the upper end portion of the battery can wall was prevented from being inward from before the caulking pretreatment. For this reason, the caulking pretreatment unit 16 is formed in a shape in which the battery can wall is curved outward.

As shown in FIG. 1, after forming the stepped portion 15 and the pre-caulking processing portion 16, the other end of the positive electrode lead 9 was welded to the lower surface of the battery lid 10 for sealing the battery can 7. The battery lid 10 is assembled by laminating a lid case, a lid cap, and a cleavage valve that cleaves when the internal pressure rises, and caulking and fixing the periphery of the lid case. A non-aqueous electrolyte that can infiltrate the entire wound group 6 is poured into the battery can 7, and then the battery lid 10 is placed above the stepped portion 15 via the EPDM resin gasket so that the positive electrode lead 9 is folded. Supported. The battery can 7 is sealed by sealing the battery can wall and the peripheral portion of the battery lid 10 by bending the battery can wall inward with the lower part of the pre-caulking treatment section 16 as a fulcrum, and a capacity of 10.0 Ah lithium ion battery 20 was completed. For this reason, the pre-caulking process part 16 is bent inside the upper surface along the shape of the peripheral part of the battery cover 10, and the caulking sealing part of the lithium ion battery 20 is formed in a shape curved upward. The non-aqueous electrolyte includes lithium hexafluorophosphate in a mixed solvent in which ethylene carbonate (EC), dimethyl carbonate (DMC), and diethyl carbonate (DEC) are mixed at a volume ratio of 1: 1: 1. were used as the (LiPF ₆₎ was dissolved 1 mol / liter.

<Action etc.>
Next, the operation and the like of the lithium ion battery 20 of the present embodiment will be described.

  In the lithium ion battery 20 of the present embodiment, the stepped portion 15 is formed by contacting the stepped support 21 on the inside of the battery can 7 and pressing the stepping roller 22 on the outside of the battery can 7. For this reason, the stepped support member 21 is inserted and positioned inside the battery can 7, so that the stepped portion 15 can be formed without causing displacement due to the pressure contact force of the stepped roller 22. Further, since the stepping support 21 is brought into contact with the inner side, the stepped portion 15 can be formed without deforming and deforming the flat surface of the battery can 7 into a concave shape when the stepping roller 22 is pressed. When sealing by caulking, it is possible to ensure sealing performance. Further, by removing the stepped support 21 from the battery after the stepped portion 15 is formed, the weight can be reduced without leaving extra parts inside the battery, and the stepped support 21 is repeatedly used. Therefore, cost reduction can be achieved.

  Moreover, in the lithium ion battery 20 of the present embodiment, the peripheral surface of the battery can 7 has a corner portion formed in an R shape, and is configured by a curved surface and a flat surface. For this reason, when forming the stepped portion 15 by pressing the stepped roller 22, the stepped portion 15 can be formed substantially evenly at the corner.

  Furthermore, in the lithium ion battery 20 of this embodiment, the upper side of the stepped portion 15 is substantially perpendicular to the battery can wall. For this reason, the force applied from above at the time of caulking and fixing can be supported by one side above the stepped portion 15. In the present embodiment, the battery lid 10 is supported by the stepped portion 15 during caulking. For this reason, a complicated process of welding and fixing a member for supporting the battery lid 10 in the battery can is not required, so that the cost can be reduced and the weight can be reduced by the amount of unnecessary members. Can be planned. Furthermore, in this embodiment, since the battery can wall above the stepped portion 15 and the peripheral portion of the battery lid 10 are caulked and fixed, space saving can be achieved.

  Furthermore, in the lithium ion battery 20 of the present embodiment, the pre-caulking part 16 is formed on the battery can wall above the stepped part 15. The battery can wall and the peripheral portion of the battery lid 10 are caulked and fixed by bending inward with the lower portion of the curved caulking pretreatment portion 16 as a fulcrum. For this reason, since the pre-caulking process part 16 is bent along the shape of the peripheral part of the battery cover 10, a caulking shape can be formed substantially equally (good), and a sealing performance can be improved. Further, when the battery lid 10 is inserted into the inside of the battery can 7 in order to prevent the upper end of the battery can wall from being curved before the caulking pretreatment section 16 is formed, It can prevent that the upper part becomes obstructive.

  Furthermore, in the lithium ion battery 20 of the present embodiment, the obtuse outer angle α is formed by the oblique side below the stepped portion 15 and the battery can wall below the stepped portion 15. For this reason, when the battery can wall is gradually protruded inward by the stepping roller 22, the battery can wall below the tip of the stepping roller 22 is pushed (indented) along the gradient below the pressure contact portion of the stepping roller 22. (According to the amount), the stepped portion 15 is deformed while rising up, so that the stepped portion 15 can be formed without rupturing the battery can 7 or making an extremely thin portion, and reducing battery defects. And productivity can be improved.

  On the other hand, in the conventional lithium ion battery, the strength against the external stress on the plane of the battery peripheral surface is very low compared to the curved surface, and the battery can is distorted by the pressure contact force of the stepping roller when forming the stepped portion. Deformation into a shape different from the stepped shape. Further, when the step roller is pressed so that the lower side of the stepped portion and the battery can wall form a substantially right angle, the battery can wall is thinned and the battery can may be broken. In order to avoid these problems, when a cross-linking plate or the like is disposed in the battery, the weight of the entire battery is increased, and an extra space is required in the battery. Furthermore, when a cross-linked plate or the like is fixed to the inner wall of the battery can by welding, it is necessary to dispose the insulating member in the battery, and the battery volume increases. The lithium ion battery 20 of the present embodiment can solve these problems.

  In the present embodiment, the rectangular lithium ion battery 20 in which the peripheral surface of the battery can is composed of a curved surface and a flat surface is exemplified. However, the present invention is not limited to this, for example, a cylindrical type You may apply to a battery. As shown in FIG. 4, the cylindrical lithium ion battery 50 can be manufactured in the same process by changing each component used in the above-described lithium ion battery 20 into a shape suitable for manufacturing the cylindrical battery. it can. That is, a wound group 36 in which positive and negative electrode plates are wound around a hollow cylindrical shaft core 31 is accommodated in a cylindrical battery can 37. After the stepped portion 45 is formed on the battery can wall above the wound group 36 and the pre-caulking processing portion 46 is formed above the stepping portion 45, the battery lid 40 and the pre-caulking processing portion 46 are caulked and fixed. In this way, a lithium ion battery 50 having an outer diameter of 80 mm and a height of 90 mm and a capacity of 10.0 Ah can be completed.

  Regardless of the square shape or cylindrical shape, if the battery size is increased, the resistance to external force will be reduced even if the battery can wall has the same thickness, making it difficult to form the stepped portion without using a stepped support. In addition, the area of the caulking sealing portion is increased, and the sealing performance is easily lowered. In the present embodiment, the stepped portions 15 and 45 are formed using the stepped support and the pre-caulking process is performed, so that the caulking shape is formed almost uniformly and the caulking sealing portion is stabilized, so that the sealing property is improved. It is effective for improvement.

  In this embodiment, an example in which the outer angle α formed by the hypotenuse on the lower side of the stepped portion 15 and the battery can wall below the stepped portion 15 is about 120 degrees is shown. However, the outer angle α may be an obtuse angle. For example, the outer angle α can be changed by changing the shape of the pressure contact portion of the stepping roller 22.

  Furthermore, in the present embodiment, the winding type battery in which the positive and negative electrodes are wound around the shaft core is illustrated, but the present invention is not limited to this and is applied to a battery in which positive and negative electrode plates are laminated. Also good. Further, in the present embodiment, the lithium ion battery 20 is exemplified, but the present invention is not limited to this. For example, the present invention is applicable to alkaline batteries such as nickel metal hydride batteries and nickel cadmium batteries, lead storage batteries, and the like. Good.

  Furthermore, in the present embodiment, the steel battery can plated with nickel is illustrated, but the present invention is not limited to this, and for example, the battery can is made of an aluminum alloy or stainless steel. May be.

  Next, examples of the lithium ion batteries 20 and 50 manufactured according to the present embodiment will be described. In addition, it describes together about the battery of the comparative example produced for the comparison.

Example 1
In Example 1, the square battery can 7 was used to form the stepped portion 15 and the pre-caulking processing portion 16 (see FIG. 1).

(Example 2)
In Example 2, it produced similarly to Example 1 except not forming the caulking pre-processing part 16.

Example 3
In Example 3, a cylindrical battery can 37 was used to form a stepped portion 45 and a pre-caulking processing portion 46 (see FIG. 4).

Example 4
In Example 4, it produced like Example 3 except not forming the pre-caulking process part 46. FIG.

(Comparative Example 1)
Comparative Example 1 was the same as Example 1 except that the stepped portion was formed only by the stepped roller 22 without using the stepped support 21 and the pre-caulking processing portion 16 was not formed.

(Comparative Example 2)
Comparative Example 2 was the same as Example 3 except that the stepped portion was formed only by the stepped roller 22 without using the stepped support 21 and the pre-caulking processing portion 46 was not formed.

(Examination / Evaluation)
The following tests were performed on the batteries of the produced examples and comparative examples. First, when 100 batteries were produced, the number of production defects such as breakage of the battery can and poor caulking shape was examined. In addition, after the storage test of storing 100 manufactured batteries for 95 hours in an environment of 90 ° C. for 5 hours and then for 5 hours in an environment of −40 ° C. was repeated, the number of batteries in which leakage occurred was examined. . The test results are shown in Table 1.

  As shown in Table 1, in the batteries of Comparative Example 1 and Comparative Example 2 in which the stepped portion is formed without using the stepped support tool 21 but the pre-processing portions 16 and 46 are not formed, defects during manufacture are Many leaks were observed in many batteries. On the other hand, in the batteries of Examples 1 and 3 in which the stepped portions 15 and 45 are formed using the stepped support tool 21 and the caulking pretreatment units 16 and 46 are formed, there is no defect during manufacture. Furthermore, no leakage was observed. Further, in the batteries of Examples 2 and 4 in which the pre-caulking processing portions 16 and 46 are not formed, when the battery can wall and the battery lids 10 and 40 above the stepped portions 15 and 45 are caulked and fixed, Some distortion occurred in the caulking shape, and liquid leakage was observed in some batteries.

  From the above results, the battery cans 7 and 37 are not distorted by bringing the stepping support 21 into contact with the inside of the battery cans 7 and 37 and pressing the stepping roller 22 from the outside of the battery cans 7 and 37. It was found that the stepped portions 15 and 45 can be formed, and the battery cans 7 and 37 can be prevented from being broken or hermetically sealed by making the outer angle α an obtuse angle. Further, judging from the leakage occurrence state of the batteries of Comparative Examples 1 and 2, it was found that the battery can is particularly effective for batteries in which the peripheral surface of the battery can is a curved surface and a flat surface. Furthermore, by forming the pre-caulking processing parts 16 and 46 above the stepped parts 15 and 45, it has been found that the caulking shape can be satisfactorily formed without causing defects during caulking and sealing and the sealing performance can be improved. did.

  The present invention provides a manufacturing method of a sealed battery that can achieve weight reduction and space saving, contributes to manufacturing and sales, and can be used industrially.

It is sectional drawing of the prismatic lithium ion battery of embodiment which can apply this invention. It is a fragmentary sectional view which shows the positional relationship of the setting support with respect to a battery can and a setting roller when forming a setting part in the lithium ion battery of embodiment. It is a fragmentary sectional view which shows the positional relationship of the caulking pre-processing concave type with respect to the battery can when forming the caulking pre-processing part in the lithium ion battery of embodiment, and a caulking pre-processing convex type. It is sectional drawing of the cylindrical lithium ion battery of Example 3 which can apply this invention.

Explanation of symbols

6 Winding group (electrode group)
7 Battery can 10 Battery cover 15 Stepped part (projecting part)
16 Caulking pretreatment section 20 Lithium ion battery (sealed battery)
21 Step support (contact tool)
22 Step roller (Pressure contact)

Claims (4)

A method for producing a sealed battery in which a battery lid is caulked and fixed to an opening of a bottomed battery can in which an electrode group is accommodated, and the battery can is sealed,
After the electrode group is housed in the battery can, a contact tool is brought into contact with the inside of the battery can wall above the electrode group, the pressure contact tool is pressed from the outside of the battery can wall, and the cross section is wedge-shaped and the one side is Forming a projecting portion substantially perpendicular to the battery can wall;
Caulking and fixing the battery can wall above the projecting part and the peripheral part of the battery cover by supporting the battery cover on one side of the projecting part;
The manufacturing method characterized by including a step.   The manufacturing method according to claim 1, wherein an outer angle formed between a hypotenuse of the wedge-shaped projecting portion and a battery can wall below the projecting portion is an obtuse angle.   The manufacturing method according to claim 1, wherein a peripheral surface of the battery can is constituted by a curved surface and a flat surface.   Before the step of caulking and fixing the battery lid, the concave jig is brought into contact with the outside of the battery can wall above the projecting portion, and the convex jig is pressed from the inside to press the battery can wall. The manufacturing method according to claim 1, further comprising a step of pre-caulking to bend outward.