JP5412919B2 - Sealed battery and method for manufacturing sealed battery - Google Patents

Description

  The present invention relates to a sealed battery in which a power generation element is accommodated in a case and a lid is fitted to an opening edge of the case, and a method for manufacturing the sealed battery.

In recent years, along with the downsizing and diversification of portable electronic devices such as video cameras, mobile computers, mobile phones, etc., the battery as the power source is smaller and lighter, has high energy density, and storage stability. Therefore, there is a strong demand for the development of a secondary battery that is highly reliable and that can be repeatedly charged and discharged for a long period of time.
As a secondary battery that satisfies these requirements, a non-aqueous electrolyte secondary battery containing a non-aqueous electrolyte can be given.

A typical example of the non-aqueous electrolyte secondary battery is a lithium ion secondary battery. A lithium ion secondary battery includes a negative electrode made of an active material capable of occluding and releasing lithium ions, a positive electrode made of transition metal oxide, fluorinated graphite, a composite oxide of lithium and transition metal, and the like. A water electrolyte. The non-aqueous electrolyte is formed by mixing a lithium salt such as LiBF ₄ , LiPF ₆ , LiClO ₄ , LiAsF ₆ , LiCF ₃ SO ₃ in an aprotic organic solvent.

  As an example of a lithium ion secondary battery, a flat wound electrode group in which the positive electrode and the negative electrode are wound through a separator is accommodated in a case made of aluminum (Al) or an Al alloy, with one side opened. The opening is sealed with an Al or Al alloy lid.

  In a sealed battery such as a lithium ion secondary battery, when charged / discharged or heated under conditions exceeding the specification, gas is generated inside the battery, and the internal pressure of the battery abnormally increases. When the lid and the case cannot withstand the abnormal increase in internal pressure, there is a risk of explosion and the contents being scattered. In order to prevent this, the lid or case is provided with a cleavage valve that cleaves to release the battery internal pressure when the battery internal pressure rises above a predetermined value.

FIG. 10 is a perspective view showing a conventional battery (sealed battery) 51.
The battery 51 is a flat wound electrode in which a negative electrode plate obtained by applying a negative electrode mixture to a copper current collector and a positive electrode plate obtained by applying a positive electrode mixture to an Al current collector are wound through a separator. The group and the non-aqueous electrolyte (not shown) have a substantially rectangular parallelepiped shape with one side opened, and are accommodated in a case 52 made of Al or Al alloy, and the opening of the case 52 is covered by a lid 53 made of Al or Al alloy. It becomes obstructed.

  The center portion of the lid 53 having a substantially rectangular shape in plan view has a flat head portion and a cylindrical leg portion, and the surface of the negative electrode terminal 54 having a T shape in cross section is exposed. It is provided so as to penetrate the lid 53 in a state of being fitted into the gasket 55. In the battery 51, a portion other than the portion where the case 52 and the negative electrode terminal 54 of the lid 53 are provided becomes a positive electrode (terminal).

  The above-mentioned cleavage valve 56 having a substantially oval shape in plan view is recessed at one end of the lid 53 by pressing, and the other end of the lid 53 has a substantially rectangular shape in plan view. A recessed portion 57 is formed by press working.

FIG. 11 is a perspective view showing the lid 53. In the figure, the cleavage valve 56 and the recess 57 are omitted.
As shown in FIG. 11, each side surface of the lid body 53 is composed of a hanging surface portion 53 a that forms an angle of 90 degrees with the surface of the lid body 53, and a C surface portion 53 b formed by chamfering the back surface. .

12 is a perspective view showing a state in which the peripheral edge portion of the lid 53 and the opening edge portion of the case 52 are laser-welded, and FIG. 13 is a cross-sectional view taken along line XIII-XIII in FIG.
As shown in FIG. 12, the lid 53 is fitted to the opening edge of the case 52, and the boundary portion between the peripheral edge of the lid 53 and the opening edge (the portion indicated by the bold line in the figure) is laser welded. To do. In FIG. 13, 58 indicates a welded portion.

FIG. 14 is a cross-sectional view showing a state after the weld 58 has solidified.
When the weld 58 is solidified and contracts, the case 52 warps outward due to rigidity, and as a result, the battery 51 expands.

  In Patent Document 1, the lid is made slightly oversized from the case, and has a tapered portion near the back surface of the side of the lid, which melts to the vicinity of the root of the root portion during welding, preventing root cracks. An invention of a battery case joining method that can be performed and has good sealing performance is disclosed.

JP 2002-8615 A

In the battery case joining method of Patent Document 1, the lid is made slightly oversized from the case, and when the welded portion 58 is solidified, the joined portion is the same as or more than the battery in FIG. There was a problem that the battery was produced in a state where the case was slightly bent outward due to the solidification shrinkage.
In the conventional battery and the battery of Patent Document 1, a portion warped to the outside of the case is the maximum thickness of the battery, and reduction of the maximum thickness has been demanded.

  The present invention has been made in view of such circumstances, and the sealed battery in which the maximum thickness of the battery is reduced and the swelling during use is suppressed by being manufactured with the side surface of the case recessed inward. And it aims at providing the manufacturing method of a sealed battery.

  A sealed battery according to a first aspect of the present invention includes a power generation element accommodated in a bottomed cylindrical case having an oval or rectangular opening edge, and a lid is fitted to the opening edge. In the sealed battery formed by welding the peripheral edge of the lid and the edge of the opening, the battery is provided with an inclined portion that is inclined near the back surface of the longitudinal side surface of the lid body in the center portion in the short direction of the lid body, The side surface of the case corresponding to the side surface is welded to the peripheral edge portion of the lid and the opening edge portion in a state where the side surface is in close contact with the inclined portion so as to be recessed inward. .

  In the present invention, the case is produced with the side surface of the case being recessed inward so as to compress the power generation element, so that the case is prevented from warping outward, and the maximum thickness of the sealed battery (battery) is increased. To reduce. Swelling of the battery during use is also suppressed. And since the peripheral part of a cover body and the opening edge part of a case are welded in the state which the side surface of the case closely_contact | adhered to the inclination part of the cover body, a welding defect does not arise and the sealing property of a battery is favorable.

  The sealed battery according to a second aspect of the present invention is characterized in that, in the first aspect, the inclined portion is provided at a central portion in the longitudinal direction of the longitudinal side surface of the lid.

  In the present invention, the central portion of the side surface of the case is pressed and the inner wall of the side surface is brought into close contact with the inclined portion provided in the central portion of the lid body, and the peripheral edge portion of the lid body and the opening edge portion of the case Therefore, the maximum thickness of the battery can be effectively reduced. Moreover, since the center part of the electric power generation element which is easy to swell at the time of use is pressed, the swelling of a battery can be suppressed for a long term.

  The sealed battery according to a third invention is characterized in that, in the first invention, the inclined portion is provided so as to be gradually inclined from both end portions of the longitudinal side surface toward the central portion.

When an inclined part is provided at the end of the side surface of the lid over substantially the entire thickness of the lid, the corner of the corresponding case cannot be satisfactorily adhered to the inclined part, resulting in poor welding. Part can also occur.
In the present invention, since the inclined portion is provided so as to be gradually inclined as it goes from the both end portions of the longitudinal side surface to the central portion, the side surface of the lid body and the opening edge portion of the case are satisfactorily adhered. And can be welded well.

  A sealed battery according to a fourth invention is characterized in that, in any one of the first to third inventions, an angle formed by the inclined portion and the surface of the lid is 80 degrees or more and less than 90 degrees.

  In the present invention, the peripheral edge of the lid and the opening edge of the case can be well adhered and welded.

  A sealed battery according to a fifth aspect of the present invention is characterized in that, in any one of the first to fourth aspects, the power generation element includes a non-aqueous electrolyte.

  In the present invention, a non-aqueous electrolyte battery that is required to have a high energy density and that is required to be thin can be realized to be thin and can be prevented from being swollen during use. it can.

A method for manufacturing a sealed battery according to a sixth aspect of the invention is a method for manufacturing a sealed battery according to the first aspect of the invention, provided near the back surface of the long side surface of the lid, and a central portion in the short direction of the lid. the inclined portion which is inclined, the corresponding side of the case, in a state where the side surface is brought into close contact so as to be recessed inwardly, and Turkey to weld the opening edge portion of the the peripheral portion of the lid case Features.

  In the present invention, the battery is manufactured in a state where the inside of the case is recessed so as to press the power generation element, so that a battery having a reduced maximum thickness and suppressed swelling during use can be obtained.

  According to the present invention, since the battery is manufactured with the side surface of the case recessed inward and the power generation element pressed, the case is prevented from warping outward and the maximum thickness of the battery is reduced. Swelling of the battery during use is also suppressed. And since the peripheral part of a cover body and the opening edge part of a case are welded in the state which the side surface of the case closely_contact | adhered to the inclined part of the cover body, a welding defect does not arise and the sealing property of a battery is kept favorable. .

1 is a perspective view showing a sealed battery (battery) according to Embodiment 1 of the present invention. It is a partially broken side view which shows the cover body of the battery which concerns on Embodiment 1 of this invention. It is an expansion perspective view which shows the cover body concerning Embodiment 1 of this invention. It is the IV-IV sectional view taken on the line of FIG. It is a perspective view which shows the state which laser-welds the peripheral part of the cover which concerns on Embodiment 1 of this invention, and the opening edge part of a case. FIG. 6 is a cross-sectional view taken along line VI-VI in FIG. 5. It is a partial expanded sectional view of the battery which concerns on Embodiment 1 of this invention. It is a perspective view which shows the cover body concerning Embodiment 2 of this invention. It is a graph which shows the result of having measured the maximum thickness of a battery. It is a perspective view which shows the conventional battery. It is a perspective view which shows the cover body of the conventional battery. It is a perspective view which shows the state which laser-welds the peripheral part of the cover body of the conventional battery, and the opening edge part of a case. It is the XIII-XIII sectional view taken on the line of FIG. It is sectional drawing which shows the state after the welding part of the conventional battery solidified.

Hereinafter, the present invention will be specifically described with reference to the drawings showing embodiments thereof.
Embodiment 1 FIG.
1 is a perspective view showing a sealed battery (hereinafter referred to as a battery) 1 according to Embodiment 1 of the present invention, and FIG. 2 is a partially broken side view showing a lid 3 of the battery 1.

  The battery 1 is a lithium ion secondary battery in which a negative electrode plate formed by applying a negative electrode mixture to a copper current collector and a positive electrode plate formed by applying a positive electrode mixture to an Al current collector are wound through a separator. The flat wound electrode group and the non-aqueous electrolyte (not shown) have a substantially rectangular parallelepiped shape with one surface opened, and are accommodated in a case 2 made of Al or Al alloy, and the opening of the case 2 has a rectangular shape. It is closed by a lid 3 made of Al or Al alloy.

A negative electrode terminal 4 having a flat head portion 41 and a cylindrical leg portion 42 in a central portion of the lid 3 and having a T-shaped cross-sectional view is synthesized except for the surface of the negative electrode terminal 4. It is made of resin and is provided so as to penetrate through the lid 3 in a state surrounded by an insulating gasket 5. The negative electrode terminal 4 is made of nickel material or nickel-plated steel material. In the battery 1, a portion other than the portion where the negative electrode terminal 4 of the case 2 and the lid 3 is provided is a positive electrode (terminal).
At one end portion of the lid 3, the thickness is made thinner than the other portions in order to release the pressure when the internal pressure of the battery 1 is abnormally increased, and the cleavage valve 31 has a substantially oval shape in plan view. Is recessed by pressing. The cleavage valve 31 is provided so that the back surface is on the same plane as the back surface of the other part of the lid 3. At the other end of the lid 3, a recess 32 having a substantially rectangular shape in plan view is provided by pressing, and a projecting portion 33 is formed below the recess 32.

A synthetic resin insulator 6 is provided at the center of the back surface of the lid 3 in a state where the length of one end of the lid 3 of the insulator 6 is longer than the length of the other end. Yes. The recess 6 of the insulator 6 is made of copper and accommodates a plate-like current collector 7. A tab 71 is suspended from the current collector 7, and a negative lead connected to the negative plate of the electrode group is connected to the tab 71. The leg portion 42 of the negative electrode terminal 4 passes through the insulator 6 and the current collector 7, and then the end portion thereof is caulked to be fixed to the lid 3.
The protruding portion 33 is connected to a plate-like current collector 8 made of Al. A tab 81 suspended from the current collector 8 is connected to a positive electrode lead connected to a positive electrode plate of the electrode group.
When a battery pack is configured by arranging a protection circuit board having an input / output terminal and a protection circuit for preventing overcharge and overdischarge on the battery 1, the negative terminal 4 is connected to the protection circuit board via a lead. Connected to one connection terminal, the recess 32 is configured to be connected to the other connection terminal of the protection circuit board via the clad material and the lead.

3 is an enlarged perspective view showing the lid 3, and FIG. 4 is a cross-sectional view taken along line IV-IV in FIG. 3 and 4, the cleavage valve 31 and the recess 32 are omitted.
Each of the two longitudinal side surfaces of the lid 3 is provided with a hanging surface portion 3a and an inclined portion 3b at a portion of the central portion corresponding to approximately 1/3 of the length of the longitudinal side surface. The hanging surface portion 3 a is formed near the surface of the lid 3 so as to form an angle of 90 degrees with the surface. The inclined portion 3 b is formed closer to the back surface of the lid body 3, and is inclined to the center portion in the short direction of the lid body 3. The inclined portion 3b is formed in a portion corresponding to approximately 80% of the height (lid thickness) of the long side surface.
The portion of the side surface of the lid 3 where the inclined portion 3b is not provided is formed with a C-surface portion 3c formed by chamfering the C-surface on the back surface side, with the surface side of the lid body 3 forming 90 degrees with the surface. .
The lid 3 is manufactured by pressing so as to have the shape described above.

The inclined portion 3b is preferably formed in a portion corresponding to 1/3 or more and 1/2 or less of the length of the longitudinal side surface at the central portion of the longitudinal side surface. The inclined portion 3b is preferably formed in a portion corresponding to 30% or more of the height of the longitudinal side surface. Although the inclined part 3b may be formed over the entire height direction of the longitudinal side surface, it is preferable to provide the hanging surface part 3a on the longitudinal side surface.
The angle formed between the inclined portion 3b and the plane parallel to the surface of the lid 3 is preferably 80 degrees or more and less than 90 degrees.
The inclined portion 3b only needs to be formed on at least one longitudinal side surface of the lid body 3. However, since the maximum thickness of the battery 1 is further reduced, the inclined portion 3b is preferably formed on two longitudinal side surfaces.

Below, the manufacturing method of the battery 1 is demonstrated.
First, with the negative electrode lead of the electrode group connected to the tab 71 provided on the lid 3 and the positive electrode lead connected to the tab 81, the electrode group is inserted into the case 2, and the lid 3 is It fits into the opening edge of case 2.
Next, the peripheral edge of the lid 3 and the opening edge of the case 2 are laser welded.
5 is a perspective view showing a state in which the peripheral edge portion and the opening edge portion are laser-welded, FIG. 6 is a sectional view taken along line VI-VI in FIG. 5, and FIG. 7 is a partially enlarged sectional view. In FIG. 6, the negative electrode terminal 4 and the gasket 5 are omitted.
As shown in FIGS. 5 to 7, the central portion of the wide side surface of the case 2 is pressed inwardly so that the inner wall of the wide side surface is in close contact with the inclined portion 3 b of the lid body 3. Laser welding is performed on a portion where the peripheral edge portion is in contact with the opening edge portion (the portion indicated by a thick line in FIG. 5). Since the case 2 is pressed inward, even when the welded portion 11 is solidified and contracted, the case 2 does not warp outward and the maximum thickness of the battery 1 is reduced.
Then, the battery 1 is obtained by injecting a nonaqueous electrolyte from an injection hole (not shown) of the lid 3 and closing the injection hole.

  In the present embodiment, as described above, the inclined portion 3b is provided in the central portion of the longitudinal side surface of the lid 3, the central portion of the wide side surface of the case 2 is pressed, and the wide side surface of the case 2 is inclined. Since the peripheral edge of the lid 3 and the opening edge of the case 2 are welded in close contact with 3b, it is possible to weld with good sealing performance and to effectively reduce the maximum thickness of the battery 1. it can. Moreover, since the center part of the electric power generation element which is easy to swell at the time of use can be pressed, the swelling of the battery 1 can be suppressed in the long term.

Embodiment 2. FIG.
The battery according to the second embodiment has the same configuration as the battery 1 according to the first embodiment, and the shape of the lid 13 is different from the shape of the lid 3 according to the first embodiment.
FIG. 8 is a perspective view showing the lid 13.
The negative electrode terminal 14 having a flat head portion and a cylindrical leg portion in a central portion of the lid body 13 and having a T shape in cross section is made of a synthetic resin except for the surface of the negative electrode terminal 14. In addition, it is provided so as to penetrate through the lid body 13 while being surrounded by an insulating gasket 15.

Each of the two longitudinal side surfaces of the lid 13 is configured to be gradually inclined as it goes from both end portions to the central portion. The long side surface corresponds to approximately one third of the length of the long side surface of the central portion, the first inclined portion 13a having the largest inclination, and the inclination area and the degree of inclination gradually increase from the end toward the central portion. The second inclined portions 13b and 13b having a triangular shape in a side view are provided. The 1st inclination part 13a is formed in the part corresponded to about 80% of the height (lid body thickness) of the said longitudinal side surface.
As for the part in which the 1st inclination part 13a and 2nd inclination part 13b, 13b of a longitudinal side surface are not formed, the surface side of the cover body 3 makes | forms this surface 90 degree | times, and the back surface side is chamfered.
The short side surface of the lid body 3 is 90 degrees with the surface side of the lid body 3, and a C surface portion 13 c is formed by chamfering the back surface side.

The first inclined portion 13a is preferably formed in a portion corresponding to 1/3 or more and 1/2 or less of the length of the longitudinal side surface at the central portion of the longitudinal side surface. Moreover, it is preferable that the 1st inclination part 3 is formed in the part corresponded to 30% or more of the height of a longitudinal side surface. Although the 1st inclination part 3 may be formed over the whole height direction of a longitudinal side surface, it is preferable that a longitudinal side surface is provided with the part which makes 90 degree | times with this surface near the surface.
The angle formed between the first inclined portion 13a and the plane parallel to the surface of the lid 3 is preferably not less than 80 degrees and less than 90 degrees. Correspondingly, the second inclined portions 13b, 13b The slope is formed so as to gradually increase from the portion toward the center portion.
The first inclined portion 13a and the second inclined portions 13b and 13b may be formed on at least one longitudinal side surface of the lid 3, but the maximum thickness of the battery 1 is further reduced, so that the two longitudinal side surfaces are formed. Preferably it is formed.

  In the battery according to the second embodiment, like the battery 1 according to the first embodiment, the lid 13 is fitted to the opening edge of the case 2 and then the central portion of the wide side surface of the case 2 is recessed inside. In the state where the inner wall of the wide side is in close contact with the first inclined portion 13a and the second inclined portions 13b and 13b of the lid body 13, the peripheral edge portion of the lid body 13 and the opening edge portion are in contact with each other. It is manufactured by laser welding the part.

  In the present embodiment, the second inclined portions 13b and 13b are provided so as to be gradually inclined from the both end portions of the longitudinal side surface of the lid body 13 toward the central portion. A side surface and the opening edge part of case 2 can adhere | attach more favorably, and the peripheral part of the cover body 13 and the said opening edge part can be welded favorably. And since the inclination of the 1st inclination part 13a formed in the center part of the longitudinal side surface of the cover body 13 is the largest, when manufacturing a battery by pressing the center part of the wide side surface of case 2, it is effective. In addition, the maximum thickness of the battery can be reduced. Moreover, since the center part of the electric power generation element which is easy to swell at the time of use is pressed, the swelling of a battery can be suppressed.

  The present invention will be described below with reference to preferred examples. However, the present invention is not limited to the examples, and can be appropriately modified and implemented without departing from the scope of the present invention. .

The battery 1 according to the first embodiment was produced.
The case 2 has a width of 34 mm, a height of 36 mm, and a thickness of 5.2 mm.
The size of the lid 3 is 4.8 mm in length, 33.5 mm in width, and 0.8 mm in thickness. On the back surface of the lid 3, a C surface portion 3 c having a vertical dimension of 0.2 mm was formed.
The inclined portion 3b has a length corresponding to 1/3 of the length of the lid 3 and a height corresponding to 80% of the height of the longitudinal side of the central portion of the longitudinal side of the lid 3. Formed.
And the angle (inclination part angle) which makes the surface parallel to the surface of the lid 3 of the inclined part 3b is 80 degrees, 82 degrees, 84 degrees, 85 degrees, 86 degrees, 87 degrees, 88 degrees, 89 degrees, 89 Nine types of lids 3 were produced by changing the angle to 5 degrees. Each lid 3 is fitted to the opening edge of the case 2, the center of the wide side surface of the case 2 is pressed, and the inner wall of the wide side is pressed against the inclined portion 3 b using a YAG laser. The battery 1 of each Example was produced by laser welding the peripheral edge of the body 3 and the opening edge. The welding conditions are a laser output of 3 to 4 J and a welding speed of 10 to 15 mm / sec. As a comparative example, a lid body (corresponding to the case where the inclined portion angle is 90 degrees) having an angle between the long side surface and the surface of 90 degrees was produced, and a battery was produced in the same manner as in the example.

For each battery, the maximum thickness of the finished battery was measured.
FIG. 9 is a graph showing the results of measuring the maximum thickness of the battery, in which the horizontal axis represents the angle of the inclined portion (degrees) and the vertical axis represents the maximum thickness (mm) of the battery.
From FIG. 9, it can be seen that the maximum thickness of the battery is reduced in the example in which the angle of the inclined portion is 80 degrees or more and less than 90 degrees compared to the comparative example in which the angle is 90 degrees. Among the examples, when the inclined portion angle is 85 degrees or more and 89.5 degrees or less, the maximum thickness of the battery can be further reduced, and when the inclined portion angle is 88 degrees, the maximum thickness of the battery is reduced most. I understand that
As described above, by providing the inclined portion 3 b on the longitudinal side surface of the lid 3, the maximum thickness of the battery 1 can be satisfactorily reduced so as to approach the thickness of the narrow side surface of the case 2, and the battery 1 can be thinned. It was confirmed that it was possible.

In the first and second embodiments, the case where the side surfaces of the lid bodies 3 and 13 are provided with the C surface portions 3c and 13c closer to the back surface is described, but the present invention is not limited to this, and the R surface portion is provided. You may decide.
Moreover, it is not limited when the opening edge part of the case 2 and the cover bodies 3 and 13 make a rectangular shape, The case where the opening edge part of the case 2 and the cover bodies 3 and 13 make an oval shape may be sufficient. .
The case 2 is made of Al or Al alloy, but is not limited to this. The case 2 may be made of other metals.

Further, the present invention is not limited to the case where laser welding is performed on the peripheral edge of the lid bodies 3 and 13 and the opening edge of the case 2, but the peripheral edge of the lid and the opening edge of the case by other heat source welding such as electron beam welding. And may be welded.
Further, the case where the battery 1 is a lithium ion secondary battery has been described, but the present invention is not limited to this, and other secondary batteries such as a nickel / hydrogen secondary battery, a nickel / cadmium secondary battery, and the like A primary battery may be used.

DESCRIPTION OF SYMBOLS 1 Battery 2 Case 3, 13 Lid 3a Hanging surface part 3b Inclined part 3c, 13c C surface part 13a 1st inclined part 13b 2nd inclined part 4, 14 Negative electrode terminal 41 Head 42 Leg part 5, 15 Gasket 6 Insulator 7 8 Current collector 71, 81 Tab

Claims (6)

A power generation element is housed in a bottomed cylindrical case having an oval or rectangular opening edge, a lid is fitted to the opening edge, and the peripheral edge of the lid and the opening edge are In a sealed battery formed by welding,
Near the back side of the long side surface of the lid, provided with an inclined portion inclined in the center in the short direction of the lid,
In the state where the side surface of the case corresponding to the longitudinal side surface is in close contact with the inclined portion so that the side surface is recessed inward, the peripheral edge portion of the lid body and the opening edge portion are welded. A sealed battery. The sealed battery according to claim 1, wherein the inclined portion is provided in a central portion in a longitudinal direction of a longitudinal side surface of the lid. 2. The sealed battery according to claim 1, wherein the inclined portion is provided so as to be gradually inclined from both end portions of the longitudinal side surface toward a central portion. The sealed battery according to any one of claims 1 to 3, wherein an angle formed between the inclined portion and the surface of the lid is 80 degrees or more and less than 90 degrees. The sealed battery according to claim 1, wherein the power generation element includes a non-aqueous electrolyte. It is a manufacturing method of the sealed battery according to claim 1,
A state in which the side surface corresponding to the case is in close contact with the inclined portion that is provided near the back surface of the long side surface of the lid body and is inclined to the center portion in the short side direction of the lid body so that the side surface is recessed inside. In
Method of manufacturing a sealed battery, wherein the benzalkonium be welded to the opening edge of the case and the periphery of the lid.

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