Method for manufacturing power storage device and power storage device

Abstract

The present application relates to a method of manufacturing an electricity storage device and an electricity storage device. The method of manufacturing an electricity storage device includes a housing main body preparation step, a seal plate preparation step, and a welding step. The seal plate prepared in the seal plate preparation step has a seal portion that covers an opening of the housing main body and overlaps an edge of the opening, and an insertion portion that enters into the opening along an inner side of the housing main body in a state where the seal plate plugs the opening. In the step of laser welding the housing main body and the seal plate, the junction of the edge of the opening and the seal portion is welded by irradiating laser to a portion on the seal portion side than the junction of the edge of the opening and the seal portion.

Description

Technical Field

[0001] This invention relates to a method for manufacturing energy storage devices and to energy storage devices. Background Technology

[0002] Japanese Patent Application Publication No. 2018-001245 discloses a battery manufacturing method including a process (welding process) of laser welding multiple metal plates used to form a casing for housing a battery pack. In two metal plates welded along their respective edge ends, one metal plate (first metal plate) has a predetermined welding portion along its edge end, and an opening (connecting path) penetrating the metal plate in the thickness direction along the predetermined welding portion on the side opposite to the edge end relative to the predetermined welding portion. The other metal plate (second metal plate) is bent at a right angle along its edge end in a manner that it stands upright at a portion (edge ​​end portion), and a predetermined protrusion (barrier portion) is formed between the edge end (including the predetermined welding portion) and the predetermined welding portion at the upright end. In the welding process, with the two edge ends of the first and second metal plates partially positioned such that the raised portion of the second metal plate partially enters the opening of the first metal plate, and the predetermined welding points of the two metal plates face each other with a small gap between them (lap joint), a laser is irradiated and scanned from the first metal plate towards the predetermined welding points of the two metal plates. According to Japanese Patent Application Publication No. 2018-001245, in such a welding process where the edge ends of metal plates are divided into relatively complex shapes, the gas generated during laser welding can be discharged outside the housing through the opening of the first metal plate, and the raised portion of the second metal plate can prevent welding spatter from entering the housing. Summary of the Invention

[0003] In addition, the inventors of this application intend to provide a new method for manufacturing an energy storage device suitable for suppressing the entry of welding spatter into the housing when welding a sealing plate that blocks the opening of the housing body to the housing body, and the energy storage device thereby manufactured.

[0004] The method for manufacturing an energy storage device disclosed herein includes: a step of preparing a housing body with at least one side opening; a step of preparing a sealing plate for blocking the opening; and a step of laser welding the housing body to the sealing plate while the sealing plate is installed on the housing body in a manner that blocks the opening. The sealing plate prepared in the step of preparing the sealing plate has: a sealing portion that covers the opening and overlaps the edge of the opening; and an insertion portion that, while the sealing plate blocks the opening, enters into the opening along the inner side of the housing body. In the step of laser welding the housing body to the sealing plate, the edge of the opening is welded to the junction of the sealing portion and the sealing portion by irradiating a portion of the housing body closer to the sealing portion than the junction of the edge of the opening and the sealing portion.

[0005] According to this method, during the laser welding process of the shell body and the sealing plate, welding spatter is less likely to enter the shell. Attached Figure Description

[0006] Figure 1 This is a perspective view of an energy storage device according to one embodiment of the present invention.

[0007] Figure 2 It is represented by flipping up and down. Figure 1 Another perspective view of the energy storage device shown.

[0008] Figure 3 express Figure 1 The internal structure of the energy storage device shown.

[0009] Figure 4 This is a flowchart of a method for manufacturing an energy storage device according to one embodiment of the present invention.

[0010] Figure 5 This is a side view of the sealing plate prepared during the sealing plate preparation process.

[0011] Figure 6 This is a partially enlarged sectional view showing the state in which a sealing plate is installed on the main body of the casing during the manufacturing process of an energy storage device.

[0012] Figure 7 This is a partially enlarged sectional view showing the welding process in the manufacturing method of energy storage equipment.

[0013] Figure 8 It means in Figure 7 The diagram shows a partially enlarged cross-sectional view of the welding process in which a molten portion and a pinhole are formed.

[0014] Figure 9 It means Figure 8 A partially enlarged sectional view of the state after the welding process is shown.

[0015] Figure 10 It means Figure 1 A partially enlarged cross-sectional view of the welding process in a variation of the manufacturing method of the energy storage device shown. Detailed Implementation

[0016] Hereinafter, embodiments of the technology disclosed herein will be described with reference to the accompanying drawings. The embodiments described herein are not intended to specifically limit the invention. The drawings are schematic and do not necessarily reflect the actual object. Furthermore, components and parts that perform the same function are appropriately labeled with the same reference numerals, and repetitive descriptions are omitted where appropriate. Additionally, in this specification, expressions such as "X~Y" indicating numerical ranges refer to "X and above and Y and below" unless otherwise specified.

[0017] In this specification, "energy storage device" refers to a device capable of charging and discharging. Energy storage devices include batteries commonly referred to as lithium-ion batteries or lithium secondary batteries, as well as lithium polymer batteries and nickel-metal hydride batteries. A secondary battery is a general-purpose battery that can be repeatedly charged and discharged due to the movement of charge carriers between the positive and negative electrodes. Energy storage devices can use either liquid electrolytes or solid electrolytes. For example, a secondary battery can be a so-called liquid electrolyte secondary battery or a so-called all-solid-state battery using a solid electrolyte. Additionally, energy storage devices also include capacitors such as double-layer capacitors and lithium-ion capacitors.

[0018] Figure 1 This is a perspective view of an energy storage device 100 as an embodiment of the present invention. Figure 2 It is represented by flipping up and down. Figure 1 Another perspective view of the energy storage device 100 shown. Figure 3 The internal structure of the energy storage device 100 is shown. In the following description, the reference numerals F, Rr, L, R, U, and D in the attached drawings represent front, back, left, right, top, and bottom, respectively. The reference numerals X, Y, and Z in the attached drawings represent the thickness direction, the width direction orthogonal to the thickness direction, and the up and down direction orthogonal to both the width and thickness directions, respectively.

[0019] like Figures 1 to 3 As shown, the energy storage device 100 includes a housing body 10, two sealing plates 20 (sealing plate 20A and sealing plate 20B), a positive terminal 30, a negative terminal 40, and an electrode body 50. Figure 3 (as shown) and electrolyte (not shown). In this embodiment, the energy storage device 100 is a lithium-ion secondary battery.

[0020] The housing body 10 and the sealing plates 20A and 20B form the housing C of the energy storage device 100. The housing C houses the electrode body 50 and the electrolyte. The housing C is box-shaped. The housing C has a flat and rectangular (e.g., square) shape.

[0021] like Figure 3 As shown, in this embodiment, the housing body 10 is a cylindrical housing with openings 10A at both ends (i.e., in this embodiment, the housing body 10 has openings on both sides). Specifically, the housing body 10 has edge ends 10E defining the openings 10A at both ends in the width direction Y. The edge ends 10E surround the openings 10A. That is, the edge ends 10E are the edges of the openings 10A. In addition, the housing body 10 has a shape that extends along the width direction Y. Such a housing body 10 is made of metal. Examples of materials that can be used to construct the housing body 10 include aluminum, aluminum alloys, iron, and iron alloys. From the viewpoint of balancing the lightweight of the housing body 10 and the required rigidity, the preferred material for constructing the housing body 10 is aluminum or an aluminum alloy with aluminum as the main component.

[0022] like Figure 1 and Figure 2 As shown, the shell body 10 has a pair of narrow side surfaces 11 and 12 and a pair of wide side surfaces 13 and 14 as shell walls. The narrow side surfaces 11 and 12 each have a generally rectangular shape with a long side extending in the width direction Y and a short side extending in the thickness direction X, and extending in both directions. The pair of narrow side surfaces 11 and 12 face each other in the vertical direction Z. The narrow side surface 11 forms the upper surface of the shell C or shell body 10. The narrow side surface 12 forms the lower surface of the shell body 10.

[0023] The wide sides 13 and 14 each have a generally rectangular shape with a long side extending in the width direction Y and a short side extending in the vertical direction Z, and extending in both directions. The pair of wide sides 13 and 14 face each other in the thickness direction X. The wide side 13 forms the front surface of the shell body 10. The wide side 14 forms the rear surface of the shell body 10. One long side of the wide side 13 (front surface) is connected to one long side of the narrow side 11 (upper surface), and the other long side of the wide side 13 is connected to one long side of the narrow side 12 (lower surface). One long side of the wide side 14 (rear surface) is connected to the other long side of the narrow side 11, and the other long side of the wide side 14 is connected to the other long side of the narrow side 12.

[0024] The end of one of the narrow sides 11, 12 and the wide sides 13, 14 in the width direction Y (in Figure 1 and Figure 2 The right end of the middle section is one edge end 10E that forms part of the main body 10 of the housing. Figure 3As shown), the other end in the width direction Y (in Figure 1 and Figure 2 The left end of the middle section constitutes the other edge end 10E of the main body 10 of the shell. Figure 3 (As shown). Such a housing body 10 is formed, for example, by bending a metal sheet into a cylindrical shape and then joining the seams. As a joining method, welding can be cited as an example.

[0025] In this embodiment, such as Figure 2 As shown, a gas discharge valve 15 is provided on the narrow side 12 (lower surface). The gas discharge valve 15 is configured to break when the pressure inside the housing C rises above a predetermined value. By breaking the gas discharge valve 15, the gas inside the housing C is discharged to the outside of the housing C, preventing or suppressing further pressure rise inside the housing C. Such a gas discharge valve 15 can be a cross-shaped cut, a linear cut (only vertical or horizontal lines), an elliptical valve (with a cut inside), or a circular valve (with a cut inside). Figure 2 The example shown illustrates a cross-shaped cut in the gas discharge valve 15. The dimensions (length, depth) of the cut in the gas discharge valve 15 can be appropriately determined, for example, taking into account the pressure resistance of the housing C. Within the housing C, the gas discharge valve 15 can also be located in a location other than the narrow side 12; for example, it can be located on the narrow side 11, the wide side 13, the wide side 14, the sealing plate 20A, or the sealing plate 20B. Furthermore, the number of gas discharge valves 15 located in the housing C can be one or more. Figure 2 This example illustrates the case where there is only one gas discharge valve 15.

[0026] Sealing plate 20 (sealing plate 20A, sealing plate 20B) is used to seal the opening 10A of the main body 10 of the shell. Figure 3 (As shown) The blocking component. The sealing plate 20A blocks one side of the housing body 10 (in Figure 3 The opening 10A (on the right side) is blocked, and the sealing plate 20B blocks the other side (in... Figure 3 The opening 10A (left side) is blocked. The sealing plate 20 blocks the opening 10A by welding it to one edge end 10E (edge ​​of the opening 10A) of the housing body 10 along its entire circumference. The welding method will be described later. Figure 9 This is an enlarged cross-sectional view of the welded area between the main shell 10 and the sealing plate 20, and its vicinity, after the welding. (See attached image.) Figure 9 As shown, in this embodiment, the sealing plate 20 has a sealing portion 21 and an insertion portion 22.

[0027] In this embodiment, the sealing portion 21 has a first surface 21a, a second surface 21b, and an outer peripheral end 21c. In the sealing portion 21, the first surface 21a is located on the side of the opening 10A of the housing body 10, and the second surface 21b is located on the opposite side of the first surface 21a. The outer peripheral end 21c surrounds the first surface 21a and the second surface 21b. In this embodiment, the sealing portion 21 is a generally rectangular flat plate when viewed from above, having a size and shape capable of closing the opening 10A of the housing body 10. Such a sealing portion 21 covers the opening 10A of the housing body 10 and overlaps with the edge of the opening 10A. Specifically, the sealing portion 21 of the sealing plate 20 faces the opening 10A in the housing body 10 and its edge end 10E, blocking the opening 10A.

[0028] The insertion portion 22 of the sealing plate 20 is located on the first surface 21a of the sealing portion 21, and enters the opening 10A along the inner side 10a of the edge end 10E of the housing body 10 (in Figures 6 to 10 In the diagram, the boundary between the sealing portion 21 and the insertion portion 22 is indicated by a dashed line.

[0029] Such a sealing plate 20 joins the edge end 10E of the housing body 10 in the entire circumferential area of ​​the opening 10A, thereby sealing the housing C in an airtight manner. Specifically, the housing C has a welded portion W in the area including the junction of the housing body 10 and the sealing plate 20. The welded portion W is a portion that is temporarily melted and solidified by laser welding, as described later. The welded portion W has a penetration depth d1 in a direction orthogonal to the aforementioned width direction Y. The welded portion W has a peak penetration depth d1 in the width direction Y at a portion closer to the sealing portion 21 than the junction of the edge (edge ​​end 10E) of the opening 10A and the sealing portion 21. In addition, the welded portion W has a peak penetration depth d1 in the width direction Y at a portion closer to the sealing portion 21 than the junction of the sealing portion 21 and the insertion portion 22. Figures 6 to 10 (Represented by dashed lines) The part near the sealing part 21 has a peak value of melting depth d1.

[0030] The penetration depth d1 is longer than the distance d2 from the outer peripheral end 21c of the sealing portion 21 to the insertion portion 22 in a direction orthogonal to the width direction Y. From the viewpoint of reliably welding the mating portion of the housing body 10 and the sealing plate 20 to ensure the strength of the welded portion, the ratio of penetration depth d1 to distance d2 (d1 / d2) is preferably 1.1 or more, more preferably 1.2 or more, and even more preferably 1.3 or more. From the viewpoint of improving the efficiency of the welding process described later, and thus the manufacturing efficiency of the energy storage device 100, the ratio (d1 / d2) is preferably 2.0 or less, more preferably 1.7 or less, and even more preferably 1.5 or less.

[0031] In this embodiment, such as Figure 1As shown, a liquid injection hole 25 is provided on the sealing plate 20A. The liquid injection hole 25 is a hole for injecting electrolyte into the interior of the housing C after the sealing plates 20A and 20B are assembled into the housing body 10. The liquid injection hole 25 is sealed by the sealing member 26 after the electrolyte is injected. Such a liquid injection hole 25 can be provided on the sealing plate 20B or on the housing body 10 in the housing C instead of being provided on the sealing plate 20A. In addition, the liquid injection hole 25 can be provided on the surface of the housing C where the gas exhaust valve 15 is provided, or it can be provided on a different surface than the surface where the gas exhaust valve 15 is provided.

[0032] like Figure 1 As shown, the positive terminal 30 is mounted on the sealing plate 20A. Specifically, the sealing plate 20A has a terminal opening extending through its sealing portion 21 in the thickness direction, and the positive terminal 30 is mounted in this opening with an insulating gasket sandwiched between it and the sealing plate 20A. One possible method for mounting the positive terminal 30 relative to the sealing plate 20A is riveting. The positive terminal 30 protrudes both outside and inside the housing C. Figure 3 As shown, inside the housing C, the positive terminal 30 is connected to the positive current collector 31. This positive terminal 30 is preferably made of metal, more preferably of aluminum or an aluminum alloy.

[0033] like Figure 2 As shown, the negative terminal 40 is mounted on the sealing plate 20B. Specifically, the sealing plate 20B has a terminal opening extending through its sealing portion 21 in the thickness direction, and the negative terminal 40 is mounted in this opening with an insulating gasket sandwiched between it and the sealing plate 20B. One possible method for mounting the negative terminal 40 relative to the sealing plate 20B is riveting. The negative terminal 40 is exposed both outside and inside the housing C. Figure 3 As shown, inside the housing C, the negative terminal 40 is connected to the negative current collector 41. This negative terminal 40 is preferably made of metal, more preferably of copper or a copper alloy.

[0034] like Figure 3 As shown, the electrode body 50 is housed in the housing C or the housing body 10. The electrode body 50 has a positive electrode 51 and a negative electrode 52. In this embodiment, the electrode body 50 is a so-called wound electrode body. The electrode body 50 is formed by winding a laminate of strip-shaped positive electrode 51 and strip-shaped negative electrode 52 in the longitudinal direction with a winding axis as the center. Instead of such a structure, the electrode body 50 may also be a laminated electrode body in which square positive electrode and square negative electrode are stacked in a mutually insulated state.

[0035] In this embodiment, the electrode body 50 has a flat shape. The electrode body 50 has a pair of curved portions and a pair of flat surfaces connecting the curved portions. This electrode body 50 (wound electrode body) is housed within the housing C with its winding axis oriented in the width direction Y. The pair of curved portions of the electrode body 50 face the pair of narrow side surfaces 11 and 12 of the housing body 10. Alternatively, the electrode body 50 can also be housed within the housing C with its winding axis oriented in the vertical direction Z.

[0036] The positive electrode 51 of the electrode body 50 has, for example, a stacked structure of a positive current collector and a positive active material layer. The positive current collector is, for example, strip-shaped and made of a conductive metal. Examples of conductive metals include aluminum, aluminum alloys, nickel, and stainless steel. The positive current collector is preferably a conductive metal foil, more preferably an aluminum foil. The positive active material layer is, for example, formed in a strip shape along the length direction on at least one surface of the strip-shaped positive current collector. The positive active material layer includes a positive active material capable of reversibly attracting and releasing charge carriers and a binder. The positive active material is preferably a lithium transition metal composite oxide. Specific examples of this oxide include lithium cobalt composite oxide, lithium manganese composite oxide, lithium nickel composite oxide, lithium nickel manganese composite oxide, lithium nickel cobalt composite oxide, and lithium nickel cobalt manganese composite oxide. As a binder, for example, polyvinylidene fluoride (PVdF) can be used.

[0037] The negative electrode 52 of the electrode body 50 has, for example, a laminated structure of a negative current collector and a negative active material layer. The negative current collector is, for example, strip-shaped and made of a conductive metal. Examples of conductive metals used for the negative electrode include copper, copper alloys, nickel, and stainless steel. The negative current collector is preferably a conductive metal foil, more preferably a copper foil. The negative active material layer is, for example, formed in a strip shape along the length direction on at least one surface of the strip-shaped negative current collector. The negative active material layer includes a negative active material capable of reversibly absorbing and releasing charge carriers and a binder. Examples of negative active materials include carbon materials such as graphite and carbon. Examples of binders used for the negative active material include styrene-butadiene rubber (SBR) and carboxymethyl cellulose (CMC).

[0038] A separator is a component used to insulate the positive electrode active material layer from the negative electrode active material layer while maintaining ionic conductivity between the two layers. Preferably, the separator is a porous resin sheet made of a polyolefin resin. Examples of polyolefin resins include polyethylene (PE) and polypropylene (PP). A heat resistance layer (HRL) containing inorganic fillers may also be provided on the surface of the separator. Examples of materials constituting the inorganic fillers include alumina, boehmite, aluminum hydroxide, and titanium dioxide.

[0039] like Figure 3As shown, the electrode body 50 has a positive electrode tab 53 and a negative electrode tab 54 extending in opposite directions. The positive electrode tab 53 is located at one end of the electrode body 50 in the width direction Y (in... Figure 3 (The middle part is on the right) extends towards the sealing plate 20A. The positive electrode tab 53 constitutes part of the positive electrode 51. Specifically, the positive electrode tab 53 is the part of the positive current collector (strip) in the positive electrode 51 that is exposed on its surface where the positive active material layer is not stacked. Multiple positive electrode tabs 53 are provided at predetermined intervals along the length of the positive current collector. In the electrode body 50, which is a wound electrode body, such multiple positive electrode tabs 53 overlap and are connected to the positive current collector 31. The electrode body 50 is electrically connected to the positive terminal 30 via the positive current collector 31. The negative electrode tab 54 is located at the other end of the electrode body 50 in the width direction Y (in... Figure 3 (The middle part is on the left) extends towards the sealing plate 20B. The negative electrode tab 54 constitutes part of the negative electrode 52. Specifically, the negative electrode tab 54 is the part of the negative electrode current collector (strip) in the negative electrode 52 that is exposed on its surface where the negative electrode active material layer is not stacked. A plurality of negative electrode tabs 54 are provided at predetermined intervals along the length direction of the negative electrode current collector. In the electrode body 50, which is a wound electrode body, such a plurality of negative electrode tabs 54 overlap and are connected to the negative electrode current collector 41. The electrode body 50 is electrically connected to the negative terminal 40 via the negative electrode current collector 41.

[0040] The electrolyte and electrode body 50 are housed together inside the casing C. The electrolyte is immersed in the electrode body 50. The electrolyte is typically a non-aqueous liquid electrolyte (non-aqueous electrolyte) containing a non-aqueous solvent and a supporting salt. The non-aqueous solvent may contain carbonates such as ethylene carbonate (EC), dimethyl carbonate (DMC), and ethyl methyl carbonate (EMC). The supporting salt may be, for example, a fluorinated lithium salt. Examples of fluorinated lithium salts include lithium hexafluorophosphate (LiPF6) and lithium bis(fluorosulfonyl)imide (F2LiNO4S2). The remaining electrolyte not immersed in the electrode body 50 may also accumulate inside the casing C. Alternatively, a solid electrolyte (solid electrolyte) integrated with the electrode body 50 may be used instead.

[0041] Figure 4 This is a flowchart illustrating an example of a manufacturing method for an energy storage device 100. The manufacturing method for the energy storage device 100 includes a housing body preparation step S1, a sealing plate preparation step S2, an assembly step S3, and a welding step S4.

[0042] In the shell body preparation step S1, a shell body 10 with openings 10A at both ends (a shell body 10 with at least one side opening) is prepared. The method for preparing the shell body 10 in this step is not particularly limited. The shell body 10 is prepared, for example, by bending a rectangular flat plate.

[0043] In the sealing plate preparation step S2, sealing plates 20 (sealing plate 20A, sealing plate 20B) are prepared to block the opening 10A of the housing body 10. In this step, sealing plate 20A is prepared with the positive terminal 30 installed, and sealing plate 20B is prepared with the negative terminal 40 installed. Figure 5 As shown, the sealing plate 20 prepared in this process has a sealing portion 21 and an insertion portion 22 (in Figure 5 (The diagrams of the positive terminal 30 and the negative terminal 40, which serve as electrode terminals, are omitted in the original text.)

[0044] In this embodiment, the sealing portion 21 has a first surface 21a, a second surface 21b, and an outer peripheral end 21c. The first surface 21a is the surface of the energy storage device 100 facing the opening 10A of the housing body 10, and the second surface 21b is located on the opposite side of the first surface 21a in the sealing portion 21. The outer peripheral end 21c surrounds the first surface 21a and the second surface 21b. In this embodiment, the sealing portion 21 is a generally rectangular flat plate when viewed from above, having dimensions and shape capable of closing the opening 10A of the housing body 10. The insertion portion 22 is located on the first surface 21a of the sealing portion 21, having dimensions and shape capable of entering the opening 10A of the housing body 10.

[0045] There is no particular limitation on the method for preparing the sealing plate 20. The sealing plate 20 can be prepared, for example, by machining a rectangular flat plate by making holes and then installing electrode terminals (positive terminal 30, negative terminal 40). The sealing plate preparation step S2 can be performed before or after the housing body preparation step S1. The sealing plate preparation step S2 can also be performed simultaneously with the housing body preparation step S1.

[0046] Then, in assembly step S3, the electrode body 50 is inserted into the interior of the housing body 10, and the electrode terminals (positive terminal 30, negative terminal 40) are electrically connected relative to the electrode body 50. Assembly step S3 can be performed, for example, in the following manner.

[0047] First, a plurality of overlapping positive electrode tabs 53 in the electrode body 50 are connected to a positive electrode current collector 31, and a plurality of overlapping negative electrode tabs 54 are connected to a negative electrode current collector 41. Laser welding is one example of the connection method (the same applies to the connection method described later in assembly step S3). Then, the negative electrode current collector 41 connected to the negative electrode tabs 54 is connected to a negative terminal 40 mounted on the sealing plate 20B. The portion of the negative terminal 40 exposed to the inside of the housing of the sealing plate 20B is connected to the negative electrode current collector 41 (see reference). Figure 3Then, the electrode body 50 with the sealing plate 20B bearing the negative terminal 40 is positioned with its positive terminal tab 53 facing forward from the opening 10A on one side of the housing body 10 (in... Figure 3 The opening 10A on the left side is inserted into the interior of the housing body 10. Then, the positive current collector 31 of the positive electrode tab 53 connected to the electrode body 50 is connected to the positive terminal 30 mounted on the sealing plate 20A. In the positive terminal 30, the portion exposed to the inside of the housing of the sealing plate 20A is connected to the positive current collector 31 (see reference). Figure 3 Assembly step S3 can be performed, for example, as described above. Assembly step S3 can also be performed in other steps.

[0048] Then, in the welding process S4, for each sealing plate 20, after the sealing plate 20 is installed on the housing body 10 in a manner that blocks the opening 10A, the housing body 10 and the sealing plate 20 are laser welded in this state. Figure 6 This is a partially enlarged sectional view showing the state in which the sealing plate 20 is installed on the main body 10 of the housing. For example... Figure 6 As shown, with the sealing portion 21 of the sealing plate 20 blocking the opening 10A, the insertion portion 22 enters the opening 10A along the inner side 10a of the edge end 10E of the housing body 10.

[0049] Alternatively, after the sealing plate 20 is installed on the housing body 10 and before welding, a clamping fixture can be used to press the edge end 10E of the housing body 10 and its vicinity against the insertion portion 22 of the sealing plate 20. The clamping fixture, for example, includes a pair of first clamping members that press the edge end 10E and its vicinity in a direction orthogonal to the narrow sides 11, 12, and a pair of second clamping members that press the edge end 10E and its vicinity in a direction orthogonal to the wide sides 13, 14. With such a clamping fixture, the edge end 10E and its vicinity in the narrow sides 11, 12 can be pressed against the insertion portion 22 of the sealing plate 20 by the pair of first clamping members, and the edge end 10E and its vicinity in the wide sides 13, 14 can be pressed against the insertion portion 22 by the pair of second clamping members. Through this pressing, the edge end 10E of the housing body 10 is positioned relative to the sealing plate 20 or its insertion portion 22. That is, the insertion part 22 functions as a positioning reference. In the formed housing body 10, in its natural state, it is particularly easy to position the housing in the vertical direction Z ( ) of the wide sides 13, 14. Figure 1 , 2The central portion of the housing body 10 bulges outwards. When a sealing plate 20 is installed at the opening 10A or edge 10E of the housing body 10, a gap easily forms between the housing body 10 and the sealing plate 20. In contrast, after the sealing plate 20 is installed at the edge 10E of the housing body 10, the edge 10E and its vicinity are pressed against the insertion portion 22 of the sealing plate 20 using a clamping fixture, thereby correcting the aforementioned bulge. This prevents the gap between the housing body 10 and the sealing plate 20 from forming. The narrower this gap, the better it suppresses the tendency for welding spatter during laser welding to enter the interior of the housing body 10 or the housing C.

[0050] In welding process S4, such as Figure 7 As shown, the edge of the opening 10A is welded to the sealing portion 21 of the sealing plate 20 by irradiating a laser LS onto the portion of the sealing portion 21 at the junction of the edge (edge ​​end 10E) of the opening 10A and the sealing portion 21. The irradiation direction of the laser LS relative to the sealing portion 21 is a direction that intersects (e.g., orthogonal) the width direction Y. In this embodiment, it is preferable to continuously irradiate the housing body 10 and the sealing plate 20 in the circumferential direction of the opening 10A relative to the sealing portion 21, thereby continuously welding them in the circumferential direction. As a result, the edge end 10E of the housing body 10 is joined to the sealing plate 20 in the entire circumferential region of the opening 10A, thereby forming an airtight sealed housing C.

[0051] In welding process S4, laser LS is irradiated at and around the laser-irradiated area relative to the sealing portion 21 in such a way that a molten portion and a keyhole are formed. Specifically, by laser irradiation relative to the sealing portion 21, a molten portion Wa is first formed at and around the laser-irradiated area in the sealing portion 21 (see reference). Figure 8 ), next, as Figure 8 As shown, a small hole KH is formed within the molten portion Wa. The molten portion Wa is formed over a portion of the sealing plate 20 (a portion of the sealing portion 21 and a portion of the insertion portion 22) and at least a portion of the edge end 10E of the housing body 10. The small hole KH is formed within the molten portion Wa in a manner that does not communicate with the interior of the housing body 10. In welding step S4, laser LS is irradiated under laser irradiation conditions that enable the molten portion Wa and the small hole KH to be formed as described above. Laser irradiation conditions can include the type of laser (classified from the viewpoint of energy distribution in the laser cross section), laser output, scanning speed (welding speed) of the laser irradiation area, the size of the laser spot diameter of the laser irradiation area, and the distance (offset) from the boundary between the edge of the opening 10A and the sealing portion 21 to the center of the laser irradiation area. In welding step S4, various laser welding apparatuses capable of achieving these laser irradiation conditions are used.

[0052] As types of lasers classified from the perspective of energy distribution in the cross-section of the laser beam, examples include ring-mode lasers, Gaussian lasers, and flat-top lasers. Among ring-mode lasers, examples include single-ring ring-mode lasers and ring-mode lasers having a central portion and an annular portion surrounding the central portion in the cross-section of the laser beam. With the latter type of ring-mode laser, the residual heat from the annular portion at the laser-irradiated area scanned along the predetermined welding line stabilizes the formed molten pool, reducing its fluctuations, and thus tends to reduce the generation of welding spatter.

[0053] When using a Gaussian laser or a flat-top laser, from the viewpoint of forming a sufficient molten portion Wa (covering the edge end 10E) and a sufficient pinhole KH by laser irradiation, the laser output (laser output) is preferably 500W or more, more preferably 700W or more, and even more preferably 800W or more. From the viewpoint of suppressing excessive energy input to the laser irradiation area and avoiding the formation of a pinhole (through-hole) communicating with the inside of the shell C, the laser output is preferably 6000W or less, more preferably 5500W or less, and even more preferably 5000W or less. In addition, from the viewpoint of suppressing excessive energy input to the laser irradiation area and avoiding the formation of the aforementioned through-hole, the scanning speed (welding speed) of the laser irradiation area is preferably 150mm / s or more, more preferably 180mm / s or more, and even more preferably 200mm / s or more.

[0054] When using a ring-shaped laser with a central portion and an annular portion as the laser, from the viewpoint of forming a sufficient molten portion Wa and a sufficient aperture KH by laser irradiation, the output of the central portion is preferably 600 to 800 W. When using a ring-shaped laser with a central portion and an annular portion as the laser, from the viewpoint of ensuring an appropriate welding depth for the weld portion W, the output of the annular portion is preferably 5000 to 6000 W.

[0055] When using a ring-shaped laser with a central portion and an annular portion as the laser, from the viewpoint of suppressing or preventing the formation of pores by forming a small hole of an appropriate size at the laser irradiation site, the diameter of the central portion (the diameter at the laser irradiation site or the diameter of the laser spot) is preferably 60 μm or more, more preferably 70 μm or more. From the viewpoint of suppressing or preventing the formation of through-holes at the laser irradiation site, the diameter of the central portion is preferably 90 μm or less, more preferably 80 μm or less. When using a ring-shaped laser with a central portion and an annular portion as the laser, from the viewpoint of ensuring heat input to the housing body 10 side near the laser irradiation site to form an appropriate molten portion Wa, the diameter of the annular portion (the outer diameter at the laser irradiation site) is preferably 800 μm or more. From the viewpoint of ensuring energy density at the laser irradiation site to form an appropriate molten portion Wa, the diameter of the annular portion is preferably 1000 μm or less.

[0056] When using a Gaussian laser or a flat-top laser as the laser, from the viewpoint of forming a sufficient molten portion Wa and a small hole KH by laser irradiation, the size of the laser irradiation area (spot diameter) is preferably 60 to 90 μm, more preferably 70 to 80 μm.

[0057] From the viewpoint of avoiding the formation of the aforementioned through-hole, the offset of the laser irradiation area (the distance from the end of the sealing portion facing the junction to the center of the laser irradiation area in a direction orthogonal to the junction of the edge of the opening 10A and the sealing portion 21) is preferably 0.15 mm or more, more preferably 0.20 mm or more, and even more preferably 0.25 mm or more. From the viewpoint of properly forming the aforementioned molten portion Wa (covering a portion of the sealing plate 20 and at least a portion of the edge end 10E of the shell body 10), the distance from the junction of the edge of the opening 10A (edge ​​end 10E) and the sealing portion 21 to the laser irradiation area is preferably 0.55 mm or less, more preferably 0.50 mm or less, and even more preferably 0.45 mm or less. Furthermore, from the viewpoint of avoiding the formation of the aforementioned through-hole, the aforementioned offset is preferably at least twice the size of the irradiation area, such as the laser spot diameter, more preferably at least 2.5 times, and even more preferably at least 3.0 times. From the viewpoint of properly forming the aforementioned molten portion Wa (covering a portion of the sealing plate 20 and at least a portion of the edge end 10E of the housing body 10), the aforementioned offset is preferably 8 times or less the size of the irradiated portion, such as the laser spot diameter, more preferably 7 times or less, and even more preferably 6 times or less.

[0058] After welding step S4, an electrolyte injection step is performed, followed by an aging step of charging the energy storage device 100 and then allowing it to stand for a specified time, and an inspection step to check for internal short circuits in the energy storage device 100. Specifically, in the electrolyte injection step, electrolyte is injected into the interior of the housing body 10 through the aforementioned injection hole 25. In this manner, the aforementioned energy storage device 100 can be manufactured.

[0059] In the welding step S4 of the above-mentioned energy storage device manufacturing method, by means of... Figure 7 As shown, laser LS is irradiated onto the portion of the junction between the edge (edge ​​end 10E) of the opening 10A and the sealing portion 21 of the sealing plate 20, on the side near the sealing portion 21. Figure 8 A molten portion Wa and a pinhole KH are temporarily formed in and around the laser-irradiated area in the sealing portion 21. The molten portion Wa is formed over a portion of the sealing plate 20 (a portion of the sealing portion 21 and a portion of the insertion portion 22) and at least a portion of the edge end 10E of the shell body 10. The pinhole KH is formed within the molten portion Wa in a manner that does not communicate with the interior of the shell body 10. Making the welding in the welding process S4 a pinhole welding (welding through a pinhole) is suitable for achieving a high processing speed (scanning speed of the laser-irradiated area), and therefore, it is suitable for suppressing the thermal effects around the welding area of ​​the shell C and suppressing the deformation of the material. This helps to ensure the compressive strength of the entire shell C, including the welding area. Furthermore, during laser welding in the welding process S4, by avoiding the formation of a pinhole that communicates with the interior of the shell C (i.e., becoming a non-through welding), welding spatter is less likely to enter the shell C.

[0060] In the process of laser welding the housing body 10 to the sealing plate 20, laser LS is irradiated onto a portion of the junction between the edge end 10E of the opening 10A and the sealing portion 21, near the sealing portion 21, to weld the junction of the edge end 10E of the opening 10A and the sealing portion 21. In other words, in welding step S4, laser LS is irradiated at a position appropriately separated from the junction of the edge end 10E of the opening 10A and the sealing portion 21 towards the sealing portion 21. This allows a molten portion Wa of the desired size to be formed at the junction of the edge end 10E of the opening 10A and the sealing portion 21. On the other hand, laser LS can be irradiated onto a portion closer to the sealing portion 21 than the junction to avoid forming a small hole communicating with the interior of the housing C. From this perspective, the position of the irradiated laser LS can be set to a position appropriately separated from the junction of the edge (edge ​​end 10E) of the opening 10A and the sealing portion 21 towards the sealing portion 21. Here, the distance at which the laser LS is irradiated from the junction of the edge (edge ​​end 10E) of the opening 10A and the sealing portion 21 toward the sealing portion 21 can be appropriately set according to the intensity of the laser LS required for welding, the size and shape of the spot, and the characteristics of the materials constituting the shell body 10 and the sealing plate 20 that are to be welded.

[0061] According to the inventors' understanding, in welding step S4, it is preferable to irradiate with laser LS at a position 0.15 mm to 0.55 mm away from the junction of the edge (edge ​​end 10E) of the opening 10A and the sealing portion 21 towards the sealing portion 21 (i.e., the aforementioned offset is preferably 0.15 to 0.55 mm). Such a structure is preferable in that it avoids the formation of the aforementioned through-hole during laser welding while appropriately forming the aforementioned molten portion Wa (covering a portion of the sealing plate 20 and at least a portion of the edge end 10E of the housing body 10).

[0062] According to the inventors' understanding, in welding step S4, it is preferable to irradiate with a ring-shaped laser having a central portion and an annular portion. With such a ring-shaped laser, the size (diameter) of the central portion and the laser output can be adjusted separately, making it easier to form the aforementioned molten portion Wa and its internal pinhole KH.

[0063] According to the inventors' understanding, in welding step S4, it is preferable to irradiate the laser LS at a distance of 2 to 8 times the spot diameter of the laser LS separated from the junction of the housing body 10 and the sealing portion 21 towards the sealing portion 21 (i.e., the aforementioned offset is preferably 2 to 8 times the spot diameter of the laser LS). Such a structure is preferable in that it avoids the formation of the aforementioned through-holes during laser welding while appropriately forming the aforementioned molten portion Wa (covering a portion of the sealing plate 20 and at least a portion of the edge end 10E of the housing body 10).

[0064] According to the inventors' understanding, in welding step S4, the laser spot diameter at the laser irradiation site is preferably 60 to 90 μm, and more preferably in the range of 70 to 80 μm, as described above. It is preferable to appropriately form the molten portion Wa (covering a portion of the sealing plate 20 and at least a portion of the edge end 10E of the housing body 10) while avoiding the formation of the aforementioned through-holes during laser welding.

[0065] In the energy storage device 100, as referred to Figure 9 As described above, the junction of the edge (edge ​​end 10E) of the opening 10A and the sealing portion 21 is welded (forming a welded portion W), and the welded portion W has a peak value of penetration depth d1 at the portion closer to the sealing portion 21 than the junction of the edge of the opening 10A and the sealing portion 21. This welded portion W is formed in the welding step S4 of the manufacturing process of the energy storage device 100 by the aforementioned laser welding, which simultaneously performs pinhole welding and non-through welding. Therefore, the energy storage device 100 having the welded portion W in the housing C is suitable for obtaining the same effect as described above regarding the welding step S4 in its manufacturing process (preventing welding spatter from entering the housing by simultaneously performing pinhole welding and non-through welding).

[0066] like Figure 10 As shown, the sealing plate 20 prepared in the sealing plate preparation step S2 may also have a shape in which the sealing portion 21 protrudes from the housing body 10 in a direction orthogonal to the opening direction of the opening 10A when the sealing plate 20 is installed on the opening 10A of the housing body 10. Figure 10 In the diagram, the protruding portion of the sealing part 21 is designated as protrusion 21A. In the welding process S4 following the sealing plate preparation process S2, it is compared with the reference... Figures 7 to 9 Similarly, in the welding process S4 described above, laser LS is irradiated onto the portion of the junction between the edge (edge ​​end 10E) of the opening 10A and the sealing portion 21 of the sealing plate 20, near the sealing portion 21, to weld the junction between the edge of the opening 10A and the sealing portion 21 of the sealing plate 20. In this modified example, specifically, the laser irradiation portion is the portion of the sealing portion 21 near the sealing portion 21, which is the protrusion 21A of the sealing portion 21. In this laser welding, it is easy to ensure the penetration depth and weld strength of the formed weld.

[0067] The energy storage device 100 can be used for various purposes. For example, the energy storage device 100 can be preferably used as a power source (drive power source) for an electric motor in a vehicle such as a passenger car or a truck. There is no particular limitation on the type of vehicle, but examples include plug-in hybrid electric vehicles (PHEVs), hybrid electric vehicles (HEVs), and battery electric vehicles (BEVs).

[0068] The following describes experimental examples of the technology disclosed herein. However, the technology disclosed herein is not limited to the content shown in the experimental examples.

[0069] <Example 1>

[0070] First, a housing body and a sealing plate were prepared. The housing body is a cylindrical shell (made of aluminum alloy) with openings at both ends, and the sidewall thickness is 0.65 mm. The sealing plate is a cover (made of aluminum alloy) that is roughly rectangular when viewed from above, having a sealing portion (90 mm long side × 30 mm short side × 1.0 mm thickness) and an insertion portion (1.0 mm thickness) disposed on one side, having dimensions and shape capable of closing the openings of the housing body. The outer peripheral end of the insertion portion retracts inward along the outer peripheral end of the sealing portion, and the retraction length from the outer peripheral end of the sealing portion to the outer peripheral end of the insertion portion (in... Figure 9 The distance (equivalent to d2) is 0.75 mm.

[0071] Then, the single-sided adhesive sheet (adhesive surface size approximately 4cm) used as a dust sampler was applied. 2 After being positioned near one of the openings inside the housing body, the sealing plate is installed at the edge end of the housing body (edge ​​of the opening) to block the opening. Figure 7 , 8 As shown by the imaginary line (double-dotted line), the adhesive sheet is positioned within the housing body with its adhesive surface facing the junction of the housing body and the sealing plate. During the installation of the sealing plate relative to the edge of the housing body, the insertion portion of the sealing plate is inserted into the opening. Then, using a pre-defined clamping fixture, the edge of the housing body and its vicinity are pressed against the insertion portion of the sealing plate, maintaining this position.

[0072] Then, a laser is irradiated at the junction of the edge (edge ​​end) of the opening of the main body of the housing and the sealing part of the sealing plate. The laser-irradiated area is scanned along the junction for 20 mm, thereby welding the junction of the edge of the opening and the sealing part of the sealing plate (laser welding with a welding length of 20 mm). This laser welding uses a laser welding device (product name "YLS-3000 / 5000-SM-AMB", manufactured by IPG Photonics). As the laser, a ring-mode laser is used, which has a central part (single-mode, wavelength 1070 nm) and an annular part (multi-mode, wavelength 1070 nm) surrounding the central part in the cross-section of the laser beam. For the laser irradiation conditions, the diameter of the center portion (the diameter of the laser irradiation area or the diameter of the laser spot) is set to 72 μm, the output of the center portion is set to 800 W, the diameter of the annular portion (the outer diameter of the laser irradiation area) is set to 920 μm, the inner diameter of the annular portion (the inner diameter of the laser irradiation area) is set to 210 μm, the output of the annular portion is set to 5000 W, and the scanning speed (welding speed) of the laser irradiation area is set to 200 mm / s (Table 1 shows the laser irradiation conditions). In Example 1, the laser is irradiated at the junction of the edge of the opening of the housing body and the sealing portion of the sealing plate, and the laser irradiation area is scanned by tracking this junction. Therefore, the offset of the laser irradiation area is 0.0 mm. The offset of the laser irradiation area refers to the distance from the edge (edge ​​end) of the opening facing the housing body, at the end of the sealing portion at the junction with the sealing portion, to the center of the laser irradiation area.

[0073] Then, after removing the adhesive sheet from the housing, the entire adhesive surface of the adhesive sheet was observed using a microscope, and the size and number of weld spatters attached to the adhesive surface were measured. In Example 1, the number of weld spatters with a maximum length of 60 μm or more was 3. Table 1 shows the results.

[0074] <Examples 2~6>

[0075] In addition to irradiating the portion near the sealing portion of the junction between the edge (edge ​​end) of the opening of the housing body and the sealing portion of the sealing plate during laser welding, and scanning the irradiated portion along the junction for 20 mm while maintaining a predetermined offset from the junction (as shown in Table 1), the process from preparation of the housing body and sealing plate to measurement of welding spatter was performed in the same manner as described in Example 1. Table 1 shows the measurement results.

[0076] <Examples 7~12>

[0077] Except for the change in laser irradiation conditions as shown in Table 1 during laser welding, the same procedures as those described in Example 1 were performed, from the preparation of the aforementioned housing body and sealing plate to the measurement of welding spatter. Table 1 shows the measurement results.

[0078] [evaluate]

[0079] As shown in Table 1, in Examples 1 and 7 (examples of irradiating a laser at the junction of the edge of the opening of the housing body and the sealing portion of the sealing plate), a relatively large amount of welding spatter was generated during laser welding, regardless of the size of the laser used for laser welding. In contrast, in Examples 2-6 and 8-12 (examples of irradiating a laser at a portion closer to the sealing portion than the junction of the edge of the opening of the housing body and the sealing portion of the sealing plate), the generation of welding spatter during laser welding was significantly suppressed. In Examples 2-6 (examples using a ring-shaped laser with a relatively small diameter at the center), it was confirmed that by setting the offset to 0.1 mm or more, the generation of welding spatter during laser welding could be sufficiently suppressed. In Examples 8-12 (examples using a ring-shaped laser with a relatively large diameter at the center), it was confirmed that the longer the offset, the more effectively the generation of welding spatter during laser welding could be suppressed.

[0080] Table 1

[0081]

[0082] The above provides various descriptions of the technology disclosed herein. Unless otherwise specified, the embodiments listed herein do not limit the invention. Furthermore, the technology disclosed herein is capable of various modifications; various components and processes mentioned herein can be appropriately omitted or combined without causing particular problems. Additionally, this specification includes the disclosures described below.

[0083] Item 1: A method for manufacturing an energy storage device, wherein the method for manufacturing the energy storage device includes:

[0084] The process of preparing a shell body with at least one side opening;

[0085] The process of preparing a sealing plate for plugging the opening; and

[0086] The process of laser welding the housing body to the sealing plate while the sealing plate is installed on the housing body to block the opening.

[0087] The sealing plate prepared in the process of preparing the sealing plate has the following characteristics:

[0088] A sealing portion, the sealing portion covering the opening and overlapping the edge of the opening; and

[0089] An insertion part, wherein the opening is blocked by the sealing plate, enters the opening along the inside of the housing body.

[0090] In the process of laser welding the housing body to the sealing plate,

[0091] The edge of the opening is welded to the junction of the sealing portion by irradiating a portion of the opening closer to the sealing portion than the junction of the opening edge and the sealing portion.

[0092] Item 2: In the manufacturing method of the energy storage device described in Item 1,

[0093] In the process of laser welding the housing body to the sealing plate, a laser is irradiated at a position 0.15mm to 0.55mm away from the junction of the edge of the opening and the sealing portion towards the sealing portion.

[0094] Item 3: In the manufacturing method of the energy storage device described in Item 1 or Item 2,

[0095] In the process of laser welding the housing body to the sealing plate, a ring-shaped laser having a central part and an annular part is used as the laser.

[0096] Item 4: In the manufacturing method of the energy storage device described in Item 3,

[0097] In the process of laser welding the housing body to the sealing plate, the laser is irradiated at a distance of 2 to 8 times the diameter of the laser spot, which is separated from the edge of the opening and the junction of the sealing portion towards the sealing portion.

[0098] Item 5: In the manufacturing method of the energy storage device described in Item 3 or Item 4,

[0099] In the process of laser welding the housing body to the sealing plate, the laser with a spot diameter of 60μm to 90μm is used for irradiation.

[0100] Item 6: In the manufacturing method of the energy storage device according to any one of Items 1 to 5,

[0101] The sealing plate prepared in the process of preparing the sealing plate has a shape in which the sealing portion protrudes from the main body of the housing in a direction orthogonal to the direction in which the opening is opened when the sealing plate is installed on the opening.

[0102] Item 7: An energy storage device, wherein the energy storage device comprises:

[0103] A housing body with at least one side opening; and

[0104] A sealing plate that blocks the opening.

[0105] The sealing plate has the following characteristics:

[0106] A sealing portion, the sealing portion covering the opening and overlapping the edge of the opening; and

[0107] An insertion portion that enters the opening along the inner side of the housing body.

[0108] The edge of the opening is welded to the junction of the opening and the sealing portion, and has a peak value of weld depth at the portion closer to the sealing portion than the junction of the opening and the sealing portion.

Claims

1. A method for manufacturing an energy storage device, wherein, The method for manufacturing the energy storage device includes: The process of preparing a shell body with at least one side opening; The process of preparing a sealing plate for plugging the opening; and The process of laser welding the housing body to the sealing plate while the sealing plate is installed on the housing body to block the opening. The sealing plate prepared in the process of preparing the sealing plate has the following characteristics: A sealing portion, the sealing portion covering the opening and overlapping the edge of the opening; and An insertion part, wherein the opening is blocked by the sealing plate, enters the opening along the inside of the housing body. In the process of laser welding the housing body to the sealing plate, The edge of the opening is welded to the junction of the sealing portion by irradiating a portion of the opening closer to the sealing portion than the junction of the opening edge and the sealing portion.

2. The method for manufacturing the energy storage device according to claim 1, wherein, In the process of laser welding the housing body to the sealing plate, a laser is irradiated at a position 0.15mm to 0.55mm away from the junction of the edge of the opening and the sealing portion towards the sealing portion.

3. The method for manufacturing the energy storage device according to claim 1 or 2, wherein, In the process of laser welding the housing body to the sealing plate, a ring-shaped laser having a central part and an annular part is used as the laser.

4. The method for manufacturing the energy storage device according to claim 3, wherein, In the process of laser welding the housing body to the sealing plate, the laser is irradiated at a distance of 2 to 8 times the diameter of the laser spot, which is separated from the edge of the opening and the junction of the sealing portion towards the sealing portion.

5. The method for manufacturing the energy storage device according to claim 3, wherein, In the process of laser welding the housing body to the sealing plate, the laser with a spot diameter of 60-90 μm is used for irradiation.

6. The method for manufacturing the energy storage device according to claim 1, wherein, The sealing plate prepared in the process of preparing the sealing plate has a shape in which the sealing portion protrudes from the main body of the housing in a direction orthogonal to the direction in which the opening is opened when the sealing plate is installed on the opening.

7. An energy storage device, wherein, The energy storage device includes: A housing body with at least one side opening; and A sealing plate that blocks the opening. The sealing plate has the following characteristics: A sealing portion that covers the opening and overlaps the edge of the opening; as well as An insertion portion that enters the opening along the inner side of the housing body. The edge of the opening is welded to the junction of the opening and the sealing portion, and has a peak value of weld depth at the portion closer to the sealing portion than the junction of the opening and the sealing portion.

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