Power storage device and method for manufacturing power storage device
The sealing body with a terminal body, first gasket, and second plate material improves the reliability of power storage devices by securing the seal and electrical connections, addressing leakage and reliability issues under severe conditions.
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- PANASONIC INTELLECTUAL PROPERTY MANAGEMENT CO LTD
- Filing Date
- 2025-11-25
- Publication Date
- 2026-06-04
AI Technical Summary
Existing power storage devices face challenges in maintaining reliability under severe conditions, particularly in sealing the open end of the exterior body to prevent leakage and ensure effective electrical connections.
A sealing body comprising a terminal body, a first gasket, and a second plate material is used to seal the open end of the exterior body, where the first gasket is compressed against the interior surface and laser-welded to the exterior body, ensuring a secure seal and electrical connection.
The solution enhances the reliability of power storage devices by preventing electrolyte leakage and ensuring robust electrical connections, even under severe conditions.
Smart Images
Figure JP2025041031_04062026_PF_FP_ABST
Abstract
Description
Power storage device and method for manufacturing the same
[0001] The present disclosure relates to a power storage device, particularly to the joining of an exterior body and a sealing body.
[0002] A power storage device such as a lithium-ion battery houses an electrode body and an electrolytic solution within an exterior body with one end open, and seals the open end with a sealing body. Usually, the exterior body is made of metal, one electrode of the electrode body is connected, a terminal body is disposed at the center of the sealing body, and the other electrode of the electrode body is connected thereto.
[0003] In such a power storage device, for example, with the sealing body disposed on the inner peripheral side of the upper end portion of the exterior body, the peripheral edge portion of the sealing body is sandwiched and caulked by the exterior body, thereby sealing the open end of the exterior body with the sealing body.
[0004] There is also known a structure in which the open end of the exterior body is closed with a sealing plate and the two are laser welded (see Patent Document 1).
[0005] Japanese Patent No. 6375172
[0006] In order for the power storage device to perform charging and discharging under even more severe conditions in the future, further improvement in reliability is required.
[0007] The power storage device according to the present disclosure includes an exterior body having one end as an open end in a first direction and housing an electrode body therein, and a sealing body for closing the open end of the exterior body. The sealing body includes a terminal body, a first plate material surrounding the terminal body, an annular first gasket contacting the inner peripheral surface of the exterior body, and a second plate material disposed at one end of the gasket in the first direction. The outer peripheral edge portion of the second plate material is joined to the open end of the exterior body.
[0008] Furthermore, the method for manufacturing the energy storage device involves preparing an outer casing having one end open in a first direction and housing an electrode body inside, injecting liquid into the outer casing, and pushing a sealing body, which includes a terminal body positioned in the center, a gasket covering the outer circumference of the terminal body and having a diameter larger than the inner diameter of the outer casing, and a second plate material positioned at one end of the peripheral edge of the gasket, into the interior of the outer casing from the open end of the outer casing while compressing it radially by pressing the peripheral edge of the gasket against the inner circumferential surface of the outer casing, bringing the peripheral edge of the second plate material into contact with the peripheral edge of the open end of the outer casing, and welding the peripheral edge of the second plate material and the peripheral edge of the open end.
[0009] According to the energy storage device and its manufacturing method described herein, the reliability of the energy storage device can be improved.
[0010] This figure shows the external appearance of the outer casing and sealing body of the energy storage device according to this disclosure. This is a cross-sectional view of the sealing body. This figure illustrates the process of attaching the sealing body to the outer casing. This figure shows other configuration examples for the gasket and sealing plate material. This figure shows an example of a sealing body configuration in which the cylindrical part of the terminal body and the cover plate material are separate. This figure shows an example of a configuration in which the cylindrical part of the terminal body and the cover plate material are separate and connected via a second gasket. This figure shows an example of the configuration of the first gasket. This figure shows an example of joining the outer casing and the sealing body.
[0011] The embodiments of this disclosure will be described below with reference to the drawings. The embodiments described below are not limiting to this disclosure, and configurations formed by selectively combining multiple examples are also included in this disclosure.
[0012] The energy storage device of this disclosure may be a secondary battery using an aqueous electrolyte or a secondary battery using a non-aqueous electrolyte. The energy storage device of this disclosure may be a cylindrical battery with a cylindrical (e.g., bottomed cylindrical) outer casing or a prismatic battery with a prismatic outer casing. In these batteries, the cylindrical outer casing or the prismatic outer casing constitutes the outer casing. Alternatively, the energy storage device of this disclosure may be a capacitor that undergoes repeated charging and discharging.
[0013] "Overall Configuration" Figure 1 shows the external appearance of the outer casing 10 and sealing body 12 of the energy storage device according to this disclosure, where (A) shows the sealing body 12 detached from the outer casing 10, and (B) shows the sealing body 12 attached to the outer casing.
[0014] The outer container 10 is a cylindrical container with one end open as an open end 10a in the first direction (in this case, the direction in which the electrode body and the sealing body are aligned). The sealing body 12 is a disc-shaped object corresponding to the open end 10a of the outer container 10, and closes the open end 10a. In this example, the upper side of the outer container 10 is the open end 10a, and the sealing body 10 is inserted so that its outer peripheral edge contacts the inner surface of the open end 10a of the outer container 10.
[0015] The sealing body 12 has a terminal body 20 positioned in the center, and an annular first gasket 22 is provided on the outside of the terminal body 20 in a second direction perpendicular to the first direction. The outer diameter of the first gasket 22 is larger than the inner diameter of the outer can 10, and when the sealing body 12 is inserted into the outer can 10, the outer periphery of the first gasket 22 contacts the inner circumferential surface of the outer can 10 in a compressed state. In addition, the first gasket may be subjected to force not only from the inner circumferential surface of the outer can 10 but also from the outer periphery of the first plate, resulting in a state where the first gasket is sandwiched in the second direction. Furthermore, an annular second plate material, a sealing plate material 24, is positioned on top of the first gasket 22. The outer periphery of the sealing plate material 24 and its inner circumferential surface are joined to the upper end of the outer can 10 by laser welding.
[0016] Figure 2 is a cross-sectional view of the sealing body 12, where (A) shows the state before inserting the sealing body 12 into the open end 10a of the outer can 10, and (B) shows the state after inserting the sealing body 12 into the open end 10a of the outer can 10.
[0017] The terminal body 20 has a central cylindrical portion 20a, the upper surface of which is electrically connected to the outside, and the lower surface of which is electrically connected to one electrode of the electrode body housed inside the outer casing 10.
[0018] A cover plate 20b is provided at the lower end of the cylindrical portion 20a of the terminal body 20, extending radially outward. The cover plate 20b is concentric with the cylindrical portion 20a, and its diameter is smaller than the inner diameter of the outer container 10. In this example, the cover plate 20b is configured as part of the terminal body 20, but it may be configured as a separate component, and this cover plate 20b is referred to as the first plate.
[0019] The first gasket 22 is positioned to cover the upper, outer, and lower surfaces of the peripheral edge of the cover plate material 20b of the terminal body 20. The first gasket 22 includes a U-shaped annular portion 22a that covers the cover plate material 20b, a projection 22b that protrudes radially outward from the outer peripheral end of the annular portion 22a, and a folded portion 22c that extends upward from the upper inner peripheral end of the annular portion 22a and then extends radially outward (second direction). An annular groove 22d is formed by the folded portion 22c and the upper surface of the annular portion 22a, and the inner peripheral portion of the annular sealing plate material 24 is housed in this annular groove 22d.
[0020] The protrusion 22b of the first gasket 22 extends outward and diagonally upward from the lower outer circumference of the annular portion 22a. In other words, on the outer surface of the annular portion 22a, the protrusion 22b is inclined such that the tip is closer to one end in the first direction than the base portion connected to the annular portion 22a. The inner end of the protrusion 22b, i.e., the outer circumference of the annular portion 22a, is smaller than the inner diameter of the outer can 10, while the outer circumference of the protrusion 22b is larger than the inner diameter of the outer can 10. When the sealing body 12 is inserted into the open end 10a of the outer can 10, the protrusion 22b is compressed inward, and therefore the tip of the protrusion 22b moves downward while being pressed against the inner surface of the outer can 10. Therefore, as will be described later, even if electrolyte is adhering to the inner surface of the outer can 10, the protrusion 22b of the first gasket 22 can scrape off the electrolyte.
[0021] The outer diameter of the annular sealing plate 24 is set to be the same as or slightly larger than the inner diameter of the open end 10a of the outer can 10. Therefore, as shown in Figure 2(B), when the sealing body 12 is inserted into the open end 10a of the outer can 10, the peripheral edge of the sealing plate 24 comes into contact with the inner surface of the outer can 10. Then, as indicated by the triangular mark in Figure 2(B), the outer peripheral edge of the sealing plate 24 and the inner edge of the outer can 10 are joined by laser welding using a laser. If the diameter of the sealing plate 24 is larger than the inner diameter of the outer can 10, the outer can 10 expands slightly, or the sealing plate 24 contracts slightly, or both, so that the outer peripheral edge of the sealing plate 24 is inserted into the upper end of the outer can 10. The outer diameter of the sealing plate 24 may be set to be smaller than the inner diameter of the open end 10a of the outer can 10, and the upper end of the outer can 10 may be pressed with a jig to reduce its diameter. However, in the energy storage device of this disclosure, it is not necessary to press the upper end of the outer can 10. Also, the terminal body 20 is exposed from the hollow portion of the annular sealing member 24.
[0022] Furthermore, the cover plate material 20b and sealing plate material 24 of the terminal body 20 are provided with vertically oriented protrusions, and the first gasket 22 is provided with corresponding recesses. When the two are fitted together, the radial movement of the cover plate material 20b and sealing plate material 24 is restricted. As long as the protrusions and recesses face each other, the recess may be provided on either the cover plate material 20b or the sealing plate material 24, and the protrusion may be provided on either.
[0023] The outer casing 10, terminal body 20, and sealing plate material 24 can be made of metal such as aluminum or steel, and the first gasket 22 can be made of a resin having a predetermined elasticity such as polypropylene.
[0024] "Manufacturing Process" Figure 3 is a diagram illustrating the process of attaching the sealing body 12 to the outer can 10. In the example in Figure 3, the protruding portion 22b at the outer edge of the first gasket 22 is simply a frustoconical shape with an area that widens upwards. However, even with this shape, when attaching the sealing body 12 to the outer can 10, the electrolyte can be scraped off by the tip portion, similar to the example in Figure 2.
[0025] In Figure 3(A), the sealing body 12 is positioned above the outer can 10. In this example, electrolyte droplets L are adhering to the inner surface near the open end 10a of the outer can 10. From here, the sealing body 12 descends, and in Figure 3(B), the outer edge of the first gasket 22 of the sealing body 12, for example, the outer edge of the protrusion 22b in Figure 2, comes into contact with the inner surface of the open end 10a at the upper end of the outer can 10. In Figure 3(C), the sealing body 12 descends further, with the protrusion 22b of the first gasket 22 bending inward and upward. At this time, as the protrusion 22b descends while rubbing against the inner surface of the outer can 10, electrolyte droplets L adhering to the inner surface are scraped off downwards.
[0026] As shown in Figure 3(C), when the sealing plate material 24 of the sealing body 12 reaches the inside of the open end 10a of the outer can 10, the descent of the sealing body 12 is stopped. In this example, the outer peripheral end of the sealing plate material 24 is inside the inner peripheral surface of the open end 10a of the outer can 10. As shown in Figure 3(D), the jig 30 is used to press the open end 10a radially inward from the outside, reducing the inner diameter of the open end 10a and pressing the inner peripheral surface of the open end 10a against the outer peripheral end of the sealing plate material 24. Various types of jig 30 can be used as long as the diameter of the open end 10a of the outer can 10 can be reduced.
[0027] Then, as shown in Figure 3(D), a laser is irradiated onto the contact area between the inner circumferential surface of the open end 10a and the outer circumferential end of the sealing plate material 24, causing them to melt and laser weld together.
[0028] Thus, according to this embodiment, even if electrolyte droplets L adhere to the inner circumferential surface of the open end 10a of the outer can 10, they can be scraped off. Therefore, the area to be joined can be kept free of electrolyte, preventing problems caused by the electrolyte during laser welding.
[0029] "Other Configuration Examples" Figure 4 shows other configuration examples for the first gasket 22 and sealing plate material 24.
[0030] Figure 4(A) shows the same configuration as shown in Figure 3, with the tip of the first gasket 22 being frustoconical in shape, widening upwards.
[0031] Figure 4(B) shows that the first gasket 22 does not have a folded portion 22c, and the sealing plate material 24 is positioned on the upper surface of the annular portion 22a of the first gasket 22. Even in this shape, when the sealing body 12 is inserted into the outer can 10, the electrolyte can be scraped off by the first gasket 22, and then the peripheral edge of the sealing plate material 24 can be welded to the open end 10a of the outer can 10. In other words, the sealing plate material 24 is placed afterwards. The sealing body 12 is fixed to the outer can 10 by the pressing force with the first gasket 22, but the first gasket 22 and the outer can 10 or the gasket and the sealing plate material 24 may be fixed using an adhesive or the like that does not cause problems during welding.
[0032] Figure 4(C) shows the terminal body 20 and the sealing plate material 24 formed as a single unit. The sealing plate material 24 is formed by rising upward from the peripheral edge of the cover plate material 20b of the terminal body 20 and then spreading outward in the radial direction. Therefore, when the cover plate material 20b and the sealing plate material 24 are joined together, the cross-section is U-shaped, and a part of the first gasket 22 is inserted into the U-shaped recess, fixing the gasket to the terminal body 20 and the sealing plate material 24.
[0033] In this example, as with Figures 5(C) and 6(C) described later, the terminal body 20 is electrically connected to the outer casing 10. Therefore, a special structure is adopted for the other electrode terminals, such as making the bottom of the outer casing 10 an additional electrode terminal electrically insulated from the outer casing 10. For example, a plate-shaped bottom may be formed at the other end of the outer casing in the first direction, an opening may be provided in this bottom, and a columnar terminal body provided in this opening in an electrically insulated state may be provided.
[0034] In Figure 5, the cylindrical portion 20a and the cover plate 20b of the terminal body 20 are separate components. The cover plate 20b is extended towards the center to form a disc portion 20c, on which the cylindrical portion 20a rests. A circular projection 20d is provided to surround the lower end of the cylindrical portion 20a. Therefore, the lower end of the cylindrical portion 20a is housed within the projection 20d. The cylindrical portion 20a and the disc portion 20c are fixed together by appropriate means and electrically connected.
[0035] Note that the configuration of the first gasket 22 and the sealing plate material 24 is the same as that of Figure 4(A) in Figure 5(A), Figure 5(B) in Figure 4(B), and Figure 5(C) in Figure 4(C).
[0036] In Figure 6, the cylindrical portion 20a and the cover plate material 20b of the terminal body 20 are separate components, and they are connected via a second gasket 32. Specifically, an annular groove 20e is provided in the middle of the outer peripheral wall of the cylindrical portion 20a in the vertical direction, and the second gasket 32, which has a U-shaped cross-section, is fitted into this groove, with the inner circumference of the cover plate material 20b being housed in the groove of the second gasket.
[0037] In this example, the cylindrical portion 20a of the terminal body 20 and the cover plate material 20b can be electrically insulated by the second gasket 32.
[0038] The first gasket 22 and the sealing plate material 24 are the same as those in Figure 4(A), Figure 6(B), and Figure 6(C). In the example of Figure 6(C), the lid plate material 20b and the sealing plate material 24 are connected, but the sealing plate material 24 and the cylindrical portion 20a are electrically insulated, and the cylindrical portion 20a and the outer can 10 can be connected to another electrode of the electrode body.
[0039] Thus, the terminal body 20 of the sealing body 12 may be an integrated unit including not only the cylindrical portion 20a and the cover plate material 20b, but also the sealing plate material 24, or these may be separate components. Alternatively, the cylindrical portion 20a and the cover plate material 20b may be separate components. Furthermore, the cylindrical portion 20a and the cover plate material 20b can be electrically insulated by connecting them via the second gasket 32. The cover plate material 20b and the sealing plate material 24 can also be made into a continuous, integrated component.
[0040] Figure 7 shows an example of the configuration of the protruding portion 22b of the first gasket 22.
[0041] Figure 7(A) has the same configuration as shown in Figures 4 to 6, and the protruding portion 22b has a triangular cross-section that widens upwards.
[0042] In Fig. 7(B), the protruding portion 22b is provided with a concave groove at a portion pressed against the inner peripheral surface of the outer can 10 at the tip, and a convex portion corresponding to the concave groove of the protruding portion 22b is provided on the inner peripheral surface of the outer can 10. Therefore, when the sealing body 12 is pushed into the open end 10a of the outer can 10, the convex portion on the inner peripheral surface of the outer can 10 fits into the concave groove of the protruding portion, and the two are fixed. Note that the convex and concave may be in the opposite direction, and the grooves may be provided over the circumference, or a plurality of spherical ones may be provided discretely.
[0043] In Fig. 7(C), the protruding portion 22b has a comb-like shape by providing a plurality of grooves in the vertical direction. With such a configuration, when the sealing body 12 is pushed into the outer can 10, the tip of the protruding portion 22b is easily deformed.
[0044] In Fig. 7(D), the tip of the protruding portion 22b is bent upward. Therefore, when the sealing body 12 is pushed into the outer can 10, first, a little central side of the tip of the protruding portion 22b is bent upward, and the tip portion becomes a U-shaped concave outward. And the outer-side tip portion of the sealing plate material 24 has a U-shaped concave inward corresponding to the shape of the protruding portion 22b. Therefore, when the sealing body 12 is pushed into the outer can 10 to a predetermined position, the U-shaped tip of the protruding portion 22b fits into the concave portion of the U-shaped tip of the sealing plate material 24, and the two are fixed.
[0045] The protruding portion 22b in Fig. 7(E) is similar to the configuration of Fig. 2, the tip is bent upward, and has a space opened upward there. And in the example of Fig. 7(E), an elastic member 22e having a ring shape with a circular cross-section is accommodated here. By accommodating the elastic member 22e inside the protruding portion 22b in this way, it becomes easy to change the total elasticity of the protruding portion 22b to an arbitrary value. Note that the method of accommodating the separate member is not limited to the illustrated example, and it may be embedded in the first gasket 22 or fitted from below.
[0046] Thus, in the first gasket 22, the outer peripheral side surface of the outer peripheral edge portion facing the inner peripheral surface of the outer can 10 is set such that the outer diameter at at least one location in the vertical direction is larger than the inner diameter of the outer can 10. For example, as shown in FIGS. 7(A) and 7(B), the end portion of the peripheral edge portion is tapered or dish-shaped. Further, at a plurality of locations where the end portion of the first gasket 22 contacts the outer can 10, the outer diameter thereof may be larger than the inner diameter of the outer can 10, such as a comb-tooth shape as shown in FIG. 7(C), a trap shape forming a plurality of recesses, and the like.
[0047] After the first gasket 22 is inserted into the outer can 10, the outer can 10 may be further compressed by being plastically deformed by compressing it in the radial direction, and may exhibit functions such as scraping off the electrolytic solution by downward movement and sealing.
[0048] Further, the first gasket 22 may have a deformed portion (for example, a bent portion) for fitting with other components (for example, the sealing plate material 24 shown in FIG. 7(D)) when the outer can 10 is inserted.
[0049] FIG. 8 is a diagram showing an example of the joining between the open end 10a of the outer can 10 and the outer peripheral edge portion of the sealing plate material 24 of the sealing body 12.
[0050] In FIG. 8(A), similarly to the example of FIG. 3(E), the sealing body 12 is pushed into the inner side of the outer can 10, and the outer peripheral edge portion of the sealing plate material 24 and the inner peripheral surface of the open end 10a of the outer can 10 are joined by laser welding.
[0051] In FIG. 8(B), the first gasket 22 of the sealing body 12 is pushed into the inner side of the outer can 10, but the outer peripheral edge portion of the sealing plate material 24 is placed on the open end 10a of the outer can 10, and the upper end of the outer can 10 and the lower end of the outer peripheral edge portion of the sealing plate material 24 are joined by laser welding from the side. <In Figure 8(C), which is an intermediate example between Figure 8(A) and Figure 8(B), the outer edge of the sealing plate material 24 is a slope that widens outward towards the top, and the upper end of the outer can 10 is a slope that slopes inward to receive the outer edge of the sealing plate material 24. The two are joined together by laser welding from the direction of the surfaces where the slopes meet, i.e., from diagonally above, to the upper end of the outer edge of the sealing plate material 24.
[0053] Furthermore, the first gasket 22 and the terminal body 20 may be joined by mating or insert molding. Regarding mating, the first gasket 22 may be mated before inserting it into the outer can 10, or it may be mated after insertion, or it may even be mated during insertion.
[0054] The first gasket 22 and the cover plate material 20b or sealing plate material 24 of the terminal body 20 may be joined by fitting or insert molding. Regarding fitting, the first gasket 22 may be fitted before inserting it into the outer can 10, fitted after insertion, or fitted during insertion. The first gasket 22 may not only be inserted into the outer can 10, but may also be fitted into the outer can 10.
[0055] The energy storage device in this disclosure is, for example, a battery, and a lithium-ion battery is preferably used as one example. The battery houses an electrode body and an electrolyte inside an outer casing 10. The electrode body has a positive electrode, a negative electrode, and a separator, and can have a wound structure in which the positive electrode and negative electrode are wound in a spiral shape with the separator in between. One of the positive electrode and the negative electrode may be electrically connected to the terminal body, and the other electrode may be electrically connected to the outer casing.
[0056] Furthermore, the battery has insulating plates positioned above and below the electrode bodies. A positive electrode lead attached to the positive electrode extends through a through-hole in the insulating plate towards the sealing body 12 and connects to the terminal body 20, while a negative electrode lead attached to the negative electrode extends outside the insulating plate towards the bottom of the outer casing 10 and connects to the outer casing 10.
[0057] Furthermore, although the present disclosure describes an energy storage device in which the outer casing has an opening at one end in the first direction and is sealed by a sealing body, the other end may also be open, and the opening at the other end may also be sealed by one of the sealing bodies described in the above embodiment. In this case, of the sealing bodies at both ends, at least one of the members of the first plate material and the terminal body of one of the sealing bodies is electrically insulated from the second plate material. Also, of the sealing bodies at both ends, the sealing body that is first joined to the outer casing does not need to have a first gasket. Furthermore, it may be just a metal plate material. Moreover, when sealing bodies are provided at both ends, one sealing body may be joined to the outer casing, the electrolyte may be supplied into the outer casing, and then the other sealing body may be joined to the outer casing.
[0058] 10 Outer can, 10a Open end, 12 Sealing body, 20 Terminal body, 20a Cylindrical part, 20b Cover plate material, 22 First gasket, 24 Sealing plate material, 30 Jig, 32 Second gasket, L Droplet
Claims
1. An energy storage device comprising: an outer casing having one end open in a first direction and housing an electrode body inside; and a sealing body that closes the open end of the outer casing, wherein the sealing body comprises: a terminal body; a first plate material surrounding the terminal body; an annular first gasket in contact with the inner circumferential surface of the outer casing; and a second plate material positioned at one end of the gasket in the first direction, wherein the outer peripheral edge of the second plate material and the open end of the outer casing are joined.
2. The energy storage device according to claim 1, wherein the first gasket is sandwiched and biased between the first plate material and the inner circumferential surface of the outer casing.
3. The energy storage device according to claim 2, wherein the terminal body and the first plate material are configured as a single unit.
4. The energy storage device according to claim 2, wherein the terminal body, the first plate material, and the second plate material are formed as a single unit.
5. The energy storage device according to claim 1, wherein the terminal body and the annular first plate material are connected via a second gasket.
6. The energy storage device according to claim 1, wherein a taper is formed on the outer circumferential surface of the first gasket such that the outer diameter of the first gasket decreases from one end to the other in the first direction.
7. The energy storage device according to claim 6, wherein the outer circumferential surface of the first gasket is provided with a projection that protrudes outward in a second direction perpendicular to the first direction, and the projection is biased between the first plate material and the outer casing.
8. The energy storage device according to claim 7, wherein the projection is inclined such that the tip is closer to one end than the base in the first direction.
9. The energy storage device according to claim 1, wherein the first gasket abuts against both end faces of the first plate material in the first direction.
10. The energy storage device according to claim 1, wherein a recess is formed on the outer peripheral surface of the first gasket.
11. A method for manufacturing an energy storage device, comprising: preparing an outer casing having one end open and housing an electrode body inside in a first direction; injecting liquid into the outer casing; pushing a sealing body, which includes a terminal body positioned in the center, a gasket covering the outer circumference of the terminal body and having a diameter larger than the inner diameter of the outer casing, and a second plate material positioned at one end of the peripheral edge of the gasket, into the interior of the outer casing from the open end of the outer casing while compressing it radially by pressing the peripheral edge of the gasket against the inner circumferential surface of the outer casing; bringing the peripheral edge of the second plate material into contact with the peripheral edge of the open end of the outer casing; and welding the peripheral edge of the second plate material to the peripheral edge of the open end.
12. The method for manufacturing an energy storage device according to claim 11, wherein the welding of the peripheral edge of the second plate material and the open end of the exterior body is performed by laser welding.