Battery and battery manufacturing method

Abstract

To provide a battery which can simply adjust bond strength between a metal member and a resin member, and a battery manufacturing method.SOLUTION: A battery 1 includes an electrode 10 having a positive electrode terminal 11 and a negative electrode terminal 12, and an exterior member 20 storing the electrode body 10. The exterior member 20 includes: a metal box-like box member 30 including a first side part 31 having a through hole 31a; a plate member 40 which is arranged so as to be separated from the first side part 31 inside the through hole 31a, in plan view when viewed from the side of the first side part 31; and a sealing body 50 which is brought into contact with a first contact surface 31b of the first side part 31 and a second contact surface 40a of the plate member 40, and has a resin layer 52 for sealing a gap G between the side of the first side part 31 and the plate member 40. The first contact surface 31b and the second contact surface 40a each has a plurality of recesses C aligned in a matrix form, in a part P overlapping the resin layer 52 in plan view when viewed from the side of the first side part 31. The recess C is filled with a part of the resin layer 52.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to batteries and methods for manufacturing batteries. [Background technology]

[0002] Patent Document 1 discloses a method for manufacturing a metal part to be joined with a resin part, and a composite molded product including the metal part manufactured by the manufacturing method and the resin part. In the manufacturing method of Patent Document 1, a plurality of roughened surfaces are formed by a laser on the joining surface of the metal part to which the resin part is joined. The adhesion between the resin part and the metal part is improved by adjusting the spacing between adjacent roughened surfaces and the depth of the irregularities formed on the roughened surfaces. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-111881 Summary of the Invention [Problem to be solved by the invention]

[0004] The composite molded body of Patent Document 1 is considered to be applied to an exterior member of a battery. In the exterior member of a battery, it is considered that the metal part and the resin part are separated in response to an increase in the internal pressure of the exterior member. In this case, there is a demand for a way to easily adjust the bonding strength between the metal part and the resin part depending on the type and size of the electrode body in the exterior member.

[0005] The present disclosure has been made in view of the above, and aims to provide a battery and a method for manufacturing the battery that enable easy adjustment of the bonding strength between a metal member and a resin member. [Means for solving the problem]

[0006] The battery of the present disclosure comprises an electrode body having a positive terminal and a negative terminal, and an exterior member in which the electrode body is housed, the exterior member being a metal box-like member including a side plate portion having a through hole, the box member housing the electrode body and electrically connected to the negative terminal, a plate member arranged inside the through hole and spaced apart from the side plate portion in a plan view from the side plate portion side, and electrically connected to the positive terminal, and a sealing body having a resin layer in contact with each of a first contact surface of the side plate portion and a second contact surface of the plate member and sealing a gap between the side plate portion side and the plate member, the first contact surface and the second contact surface each having a plurality of recesses arranged in a matrix at a portion overlapping with the resin layer in a plan view from the side plate portion side, and the recesses are filled with a portion of the resin layer.

[0007] The method for manufacturing a battery disclosed herein is a method for manufacturing a battery including: a box-shaped box member having side plate portions and accommodating an electrode assembly; a plate member disposed inside a through hole of the side plate portion while being spaced apart from the side plate portion; and a sealing body that contacts the side plate portion and the plate member and seals a gap between the side plate portion and the plate member, wherein a lens is provided at a portion that overlaps with the sealing body in a plan view seen from the side plate portion on a first contact surface where the side plate portion contacts the sealing body and a second contact surface where the plate member contacts the sealing body. a second step of irradiating the portion with the laser at the laser intensity determined in the first step at each of the plurality of irradiation positions determined in the first step, thereby forming a plurality of recesses arranged in a matrix in a plan view seen from the side plate portion; and a third step of bringing the side plate portion, the plate member, and the sealing body into contact with each other and thermally welding the sealing body so that a portion of the sealing body enters the recesses, thereby joining the side plate portion, the plate member, and the sealing body. [Effects of the Invention]

[0008] According to the battery and the method for manufacturing the battery of the present disclosure, the bonding strength between the metal member and the resin member can be easily adjusted. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a perspective view of a battery according to an embodiment of the present disclosure. [Figure 2] FIG. 2 is an exploded perspective view of the battery shown in FIG. [Figure 3] FIG. 3 is a cross-sectional view of the battery shown in FIG. [Figure 4] FIG. 4 is a plan view of the battery as seen from the first side portion side. [Figure 5] FIG. 5 is a partially enlarged cross-sectional view of the sealing body shown in FIG. [Figure 6] FIG. 6 is a plan view of the first contact surface and the second contact surface. [Figure 7] FIG. 7 is a cross-sectional view of the recess taken along line VII-VII shown in FIG. [Figure 8] FIG. 8 is a diagram showing the bonding strength. [Figure 9] FIG. 9 is an exploded perspective view of a battery according to a modified example of the embodiment of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments will be described in detail with reference to the drawings. Note that the present disclosure is not limited to these embodiments. Each embodiment is an example, and it goes without saying that partial substitution or combination of the configurations shown in different embodiments is possible.

[0011] <Battery 1> FIG. 1 is a perspective view of a battery 1 according to an embodiment of the present disclosure. FIG. 2 is an exploded perspective view of the battery 1 shown in FIG. 1. FIG. 3 is a cross-sectional view of the battery 1 shown in FIG. 1. The X, Y, and Z directions shown in the figures are mutually orthogonal and correspond to the width, depth, and height directions of the battery 1, respectively. It goes without saying that the X, Y, and Z directions are not limited to the directions shown in the figures.

[0012] The battery 1 is a secondary battery, such as a lithium battery. The battery 1 includes an electrode assembly 10 and an exterior member 20.

[0013] The electrode body 10 is a wound electrode body. The electrode body 10 is formed by stacking long positive and negative electrodes with a separator interposed therebetween and winding them. The electrode body 10 is flat. The electrode body 10 has a first end surface 10a and a second end surface 10b facing opposite each other in the Z direction.

[0014] The electrode assembly 10 includes a strip-shaped positive electrode terminal 11 that is electrically connected to the positive electrode, and a strip-shaped negative electrode terminal 12 that is electrically connected to the negative electrode. The positive electrode terminal 11 and the negative electrode terminal 12 are located on a first end surface 10a of the electrode assembly 10.

[0015] The exterior member 20 includes a box member 30, a plate member 40, and a sealing body 50.

[0016] The box member 30 is a metal box-shaped member that houses the electrode body 10. The box member 30 is electrically conductive. Materials for the box member 30 include, for example, Fe (iron), Cu (copper), Ni (nickel), stainless steel, iron alloys, copper alloys, and nickel alloys. The type of stainless steel is not particularly limited, but specific examples include SUS304 and SUS316.

[0017] The box member 30 has a rectangular parallelepiped shape having a first side portion 31 (corresponding to a “side plate portion”), a second side portion 32, and a third side portion 33.

[0018] The first side portion 31 is a flat plate that faces the first end surface 10a of the electrode body 10 and has a through hole 31a. The second side portion 32 is a flat plate that is located on the opposite side of the electrode body 10 from the first side portion 31. The second side portion 32 faces the second end surface 10b. The first side portion 31 and the second side portion 32 face each other in the Z direction, with the electrode body 10 in between. The third side portion 33 connects the first side portion 31 and the second side portion 32. The third side portion 33 has a rectangular cross section.

[0019] The second side portion 32 and the third side portion 33 are integral with each other to form a storage portion 30a having an opening. In the storage portion 30a, the second side portion 32 corresponds to a bottom plate, and the third side portion 33 corresponds to a side plate.

[0020] The first side portion 31 constitutes a lid portion 30b that covers the opening of the storage portion 30a. The peripheral edge of the lid portion 30b is joined to the peripheral edge of the opening of the storage portion 30a by, for example, laser welding along the entire periphery. This electrically connects the storage portion 30a and the lid portion 30b and also seals the gap between the storage portion 30a and the lid portion 30b.

[0021] The negative electrode terminal 12 is joined to the inner surface of the housing portion 30a (the inner surface of the third side portion 33) by, for example, resistance welding. As a result, the housing portion 30a is electrically connected to the negative electrode terminal 12. In other words, the box member 30 is electrically connected to the negative electrode terminal 12.

[0022] FIG. 4 is a plan view of the battery 1 as seen from the first side portion 31 side.

[0023] The plate member 40 shown in FIGS. 1, 2, 3, and 4 is flat and electrically conductive. The thickness of the plate member 40 is approximately equal to the thickness of the first side portion 31. The plate member 40 is made of aluminum, an aluminum alloy, or the like. Alternatively, the plate member 40 may be made of a clad material formed by roll-bonding an aluminum layer with a metal layer made of one or more of iron (Fe), copper (Cu), nickel (Ni), stainless steel, an iron alloy, a copper alloy, and a nickel alloy. Furthermore, the plate member 40 may be a composite member having a three-layer structure of an aluminum (Al) layer, a stainless steel layer, and a nickel layer. The type of stainless steel is not particularly limited, but examples include SUS304 and SUS316.

[0024] In a plan view seen from the first side portion 31 side, the plate member 40 is arranged inside the through hole 31a at a distance from the first side portion 31. The plate member 40 faces the first end surface 10a of the electrode body 10. In a plan view seen from the first side portion 31 side, there is a gap G between the first side portion 31 and the plate member 40 around the entire periphery of the plate member 40. The gap G electrically insulates the plate member 40 from the box member 30.

[0025] 3, the positive electrode terminal 11 is joined to the inner surface of the plate member 40 by, for example, laser welding. In this way, the plate member 40 is electrically connected to the positive electrode terminal 11.

[0026] The battery 1 also includes a first insulator 60 and a second insulator 70. The first insulator 60 is strip-shaped and is disposed on the positive electrode terminal 11. The first insulator 60 electrically insulates the positive electrode terminal 11 from the box member 30. The second insulator 70 is disposed on the first end surface 10a of the electrode assembly 10. The second insulator 70 electrically insulates the positive electrode terminal 11 from the negative electrode.

[0027] The sealing body 50 is located outside the exterior member 20 relative to the first side portion 31 and the plate member 40. The sealing body 50 seals the gap G between the first side portion 31 and the plate member 40. The sealing body 50 is annular in plan view. The plate member 40 is exposed from the inside of the sealing body 50. The sealing body 50 overlaps with the first side portion 31, the plate member 40, and the gap G in plan view from the first side portion 31 side.

[0028] Fig. 5 is a partially enlarged cross-sectional view of the sealing body 50 shown in Fig. 3. The sealing body 50 includes a base layer 51, a resin layer 52, and a protective layer 53.

[0029] The material of the base layer 51 is, for example, stainless steel. The type of stainless steel is not particularly limited, but specific examples include SUS304 and SUS316. The material of the base layer 51 may also be, for example, an elemental metal such as aluminum, iron, copper, or nickel, or an alloy thereof, such as an aluminum alloy, an iron alloy, a copper alloy, or a nickel alloy.

[0030] The resin layer 52 overlaps the base material layer 51 and contacts the first side portion 31 and the plate member 40. The resin layer 52 seals the gap G. The material of the resin layer 52 is a thermoplastic resin having electrical insulation properties. Examples of the material of the resin layer 52 include polypropylene (PP) and polyethylene (PE). The material of the resin layer 52 may also be unstretched polypropylene (CPP), polyphenylene sulfide (PPS), or the like.

[0031] The protective layer 53 overlaps the base material layer 51 on the side opposite to the resin layer 52, and protects the base material layer 51. The protective layer 53 has electrical insulation properties. The heat resistance of the protective layer 53 is higher than that of the resin layer 52. The material of the protective layer 53 is a thermoplastic resin. Examples of materials for the protective layer 53 include nylon and polyethylene terephthalate (PET).

[0032] The sealing body 50 is joined to the first side portion 31 and the plate member 40 by thermal welding. As shown in Figures 4 and 5, the first contact surface 31b of the first side portion 31 and the second contact surface 40a of the plate member 40 are in contact with the resin layer 52, and the first side portion 31 and the plate member 40 are joined to the resin layer 52.

[0033] The first contact surface 31b is a surface facing outward from the first side portion 31, and has a first portion P1 (corresponding to "portion") that overlaps with the sealing body 50 in a plan view seen from the first side portion 31. The first portion P1 extends around the entire periphery of the through hole 31a on the first contact surface 31b.

[0034] The second contact surface 40a is a surface facing outward from the plate member 40, and has a second region P2 (corresponding to "region") that overlaps with the sealing body 50 in a plan view seen from the first side portion 31. The second region P2 extends around the entire periphery of the second contact surface 40a. Hereinafter, when the first region P1 and the second region P2 are described without distinction, they will be referred to as region P.

[0035] FIG. 6 is a plan view of a portion P of the first contact surface 31b and the second contact surface 40a.

[0036] The portion P has a plurality of recesses C arranged in a matrix. The row direction is along the X direction. The column direction is along the Y direction. The plurality of recesses C are arranged at equal intervals in both the row and column directions.

[0037] FIG. 7 is a cross-sectional view of the recess C taken along line VII-VII shown in FIG.

[0038] The width of the recess C narrows from the opening that opens to the portion P toward the bottom. The inner surface of the recess C is, for example, conical. A portion of the resin layer 52 is filled in the recess C. This creates an anchor effect that improves the bonding strength between the first side portion 31 and the plate member 40 and the resin layer 52. The bonding strength between the first side portion 31 and the plate member 40 and the sealing body 50 is smaller than the bonding strength between the storage portion 30a and the lid portion 30b of the box member 30.

[0039] Furthermore, when the internal pressure of the exterior member 20 reaches a predetermined pressure, the sealing body 50 is ruptured between the first contact surface 31b of the first side portion 31 and the sealing body 50. In other words, the sealing body 50 functions as a rupture valve. The predetermined pressure is equal to or greater than the bonding strength between the first contact surface 31b of the first side portion 31 and the sealing body 50.

[0040] For example, if the positive electrode and negative electrode in the electrode body 10 are short-circuited, gas is generated from the electrode body 10 and the electrode body 10 generates abnormal heat. This softens the resin layer 52, and when the internal pressure of the exterior member 20 reaches a predetermined pressure, the resin layer 52 ruptures and the gas leaks from the gap G. This suppresses an increase in the internal pressure of the exterior member 20, ensuring the safety of the battery 1.

[0041] The predetermined pressure is set to a pressure that can ensure the safety of the battery 1. The pressure that can ensure the safety of the battery 1 varies depending on, for example, the materials of the members that make up the electrode body 10. Therefore, the bonding strength between the resin layer 52 and each of the first side portion 31 and the plate member 40 needs to be adjusted depending on the members of the electrode body 10, etc.

[0042] Furthermore, the bonding strength per unit area between each of the first side portion 31 and the plate member 40 and the resin layer 52 needs to be adjusted depending on the area of ​​the portion P. Specifically, when the size of the battery 1 is relatively small and therefore the area of ​​the portion P is relatively small, the bonding strength per unit area between each of the first side portion 31 and the plate member 40 and the resin layer 52 needs to be increased.

[0043] Therefore, in order to ensure that the bond strength between the resin layer 52 and the first side portion 31 and the plate member 40 (hereinafter referred to as the bond strength) is appropriate, the depth of the recesses C and the arrangement of the recesses C are determined.

[0044] FIG. 8 is a diagram showing the bonding strength. The horizontal axis in FIG. 8 represents the depth of the recess C ("d" in FIG. 7). The vertical axis in FIG. 8 represents the bonding strength. The bonding strength in FIG. 8 corresponds to the pressing force per unit area when the plate member 40 is pressed from the inside of the box member 30 and the resin layer 52 is torn open. The bonding strength is calculated by dividing the pressing force applied to the plate member 40 when the resin layer 52 is torn open by the area of ​​the portion P.

[0045] The points indicated by black circles, white circles, and black triangles in Figure 8 represent the results of actual measurements of the bonding strength. The depths (d) of the recesses C when the bonding strength was measured were 5 μm, 30 μm, 60 μm, and 100 μm.

[0046] Furthermore, the points indicated by black circles in Fig. 8 indicate the case where the distance (L shown in Fig. 6) between two adjacent recesses C in both the row and column directions is 50 µm. The points indicated by white circles in Fig. 8 indicate the case where the distance (L) between two recesses C is 200 µm. The points indicated by black triangles in Fig. 8 indicate the case where the distance (L) between two recesses C is 500 µm.

[0047] Furthermore, the solid and dashed curves shown in Figure 8 are approximate curves showing the relationship between the depth (d) of the recess C and the bonding strength when the distance (L) between two recesses C is 50 μm, 200 μm, and 500 μm.

[0048] The solid curve in Fig. 8 indicates a case where the plate member 40 is made of SUS304 and the second contact surface 40a is nickel-plated. The dashed-dotted curve in Fig. 8 indicates a case where the plate member 40 is made of aluminum. The solid and dashed-dotted curves in Fig. 8 indicate a case where the box member 30 is made of SUS316.

[0049] 8, when the depth (d) of the recesses C is 5 μm or more and 100 μm or less in each of the two materials of the plate member 40, the deeper the depth (d) of the recesses C, the greater the bonding strength. Also, when the distance (L) between the two recesses C is 50 μm or more and 500 μm or less in each of the two materials of the plate member 40, the smaller the distance (L) between the two recesses C, the greater the bonding strength. In other words, the depth and arrangement of the recesses C can easily adjust the bonding strength between the metal member (box member 30 and plate member 40) and the resin member (resin layer 52 of the sealing body 50).

[0050] <Method of manufacturing battery 1> Next, a method for forming the recess C and a method for joining the box member 30 and the plate member 40 to the sealing body 50 in the method for manufacturing the battery 1 will be described.

[0051] The multiple recesses C are formed by irradiating the region P with a laser. First, in a first step, multiple irradiation positions for irradiating the region P with the laser and the laser intensity are determined. The multiple irradiation positions correspond to the positions of the multiple recesses C shown in FIG. 6. That is, in the first step, the distance (L) between two adjacent recesses C in both the row and column directions is determined. The multiple irradiation positions are determined based on the bonding strength. The bonding strength is determined based on the above-mentioned predetermined pressure (the internal pressure of the exterior member 20 when the sealing body 50 is cleaved), the area of ​​the region P, etc.

[0052] The laser intensity corresponds to the depth (d) of the recess C shown in Fig. 7. The greater the laser intensity, the greater the depth (d) of the recess C. The laser intensity is determined based on the bonding strength.

[0053] Subsequently, in the second step, the region P is irradiated with a laser at each of the multiple irradiation positions determined in the first step with the laser intensity determined in the first step. As a result, multiple recesses C are formed in the region P in a matrix, as shown in FIG.

[0054] Furthermore, in a third step, the first side portion 31 and the plate member 40 are joined to the sealing body 50. As described above, with the first contact surface 31b of the first side portion 31 and the second contact surface 40a of the plate member 40 in contact with the resin layer 52 of the sealing body 50, the first side portion 31, the plate member 40, and the sealing body 50 are clamped by a jig or the like and thermally welded. This thermal welding melts the resin layer 52, and as shown in FIG. 7, a portion of the resin layer 52 enters the recess C.

[0055] As described above, the sealing body 50 is positioned outside the exterior member 20 relative to the first side portion 31 and the plate member 40. As a result, when the first side portion 31, the plate member 40, and the sealing body 50 are clamped by a thermal welding jig or the like, the first contact surface 31b and the second contact surface 40a are positioned on the same plane, and the first side portion 31, the plate member 40, and the sealing body 50 can be easily thermally welded together. Furthermore, as described above, the inner surface of the recess C has a conical shape, which makes it easy for a portion of the resin layer 52 to penetrate therein. Therefore, thermal welding between the first side portion 31, the plate member 40, and the sealing body 50 can be reliably performed, and the bonding strength of the resin layer 52 can be stabilized.

[0056] The above-described embodiments are intended to facilitate understanding of the present disclosure and are not intended to limit the present disclosure. The present disclosure may be modified or improved without departing from the spirit thereof, and equivalents thereof are also included in the present disclosure.

[0057] For example, the electrode assembly 10 may be a rectangular parallelepiped laminate in which a plurality of sheet-shaped positive electrodes and a plurality of sheet-shaped negative electrodes are alternately stacked with separators interposed therebetween.

[0058] The through hole 31 a may also be located in the third side portion 33 .

[0059] FIG. 9 is an exploded perspective view of a battery 1 according to a modified example of an embodiment of the present disclosure. In this modified example, the exterior member 120 is cylindrical. Specifically, the box member 130 is cylindrical, and the third side portion 133 is tubular. The first side portion 131, the second side portion 132, and the plate member 140 are disk-shaped. The periphery of the through-hole 131a is circular. The sealing body 150 is annular. Furthermore, in this modified example, the electrode body 110 is cylindrical.

[0060] The present disclosure may also be implemented as a combination of the following configurations.

[0061] (1) an electrode assembly having a positive electrode terminal and a negative electrode terminal; an exterior member that houses the electrode body, The exterior member is a box member that is made of metal and has a box shape including a side plate portion having a through hole, the box member accommodating the electrode assembly and electrically connecting to the negative electrode terminal; a plate member that is disposed inside the through hole and spaced apart from the side plate portion in a plan view seen from the side plate portion side, and that is electrically connected to the positive electrode terminal; a sealing body having a resin layer that contacts each of the first contact surface of the side plate portion and the second contact surface of the plate member and seals a gap between the side plate portion and the plate member, the first contact surface and the second contact surface each have a plurality of recesses arranged in a matrix at a portion overlapping the resin layer in a plan view seen from the side plate portion side; The recess is filled with a part of the resin layer. battery.

[0062] (2) The width of the recess narrows from the opening to the bottom of the recess. (1) The battery according to (1).

[0063] (3) The sealing body is a base layer overlapping the resin layer; Further provided is a protective layer overlapping the base layer on the side opposite to the resin layer, The battery according to (1) or (2).

[0064] (4) the sealing body is located outside the exterior member with respect to the side plate portion and the plate member; A battery according to any one of (1) to (3).

[0065] (5) When the internal pressure of the exterior member reaches a predetermined pressure equal to or greater than the bonding strength between the first contact surface of the side plate portion and the sealing body, the exterior member ruptures between the first contact surface of the side plate portion and the sealing body. A battery according to any one of (1) to (4).

[0066] (6) A method for manufacturing a battery comprising: a box-shaped box member having a side plate portion and accommodating an electrode assembly; a plate member disposed inside a through hole of the side plate portion while being spaced apart from the side plate portion; and a sealing body that contacts the side plate portion and the plate member and seals a gap between the side plate portion and the plate member, a first step of determining a plurality of irradiation positions and intensities of the laser to be irradiated with a laser at portions of a first contact surface where the side plate portion contacts the sealing body and a second contact surface where the plate member contacts the sealing body, the portions overlapping with the sealing body in a plan view seen from the side plate portion; a second step of irradiating the laser beam onto the portion at each of the plurality of irradiation positions determined in the first step with the laser intensity determined in the first step, thereby forming a plurality of recesses arranged in a matrix in a plan view seen from the side plate portion; a third step of bringing the side plate portion and the plate member into contact with the sealing body and thermally welding them so that a part of the sealing body enters the recess, thereby joining the side plate portion and the plate member to the sealing body, How batteries are manufactured. [Explanation of symbols]

[0067] 1 battery 10 Electrode body 11 Positive terminal 12 Negative terminal 20 Exterior materials 30 Box material 31 First side portion (side plate portion) 31a Through hole 31b 1st contact surface 40 Plate members 40a 2nd contact surface 50 Sealing body 51 Base material layer 52 Resin layer 53 Protective layer C recess G Gap P part P1 1st part (part) P2 2nd part (part)

Claims

1. an electrode assembly having a positive electrode terminal and a negative electrode terminal; an exterior member in which the electrode body is housed, The exterior member is a box member that is made of metal and has a box shape including a side plate portion having a through hole, the box member accommodating the electrode body and being electrically connected to the negative electrode terminal; a plate member that is disposed inside the through hole and spaced apart from the side plate portion in a plan view seen from the side plate portion side, and that is electrically connected to the positive electrode terminal; a sealing body having a resin layer that contacts each of the first contact surface of the side plate portion and the second contact surface of the plate member and seals a gap between the side plate portion and the plate member, the first contact surface and the second contact surface each have a plurality of recesses arranged in a matrix at a portion overlapping the resin layer in a plan view seen from the side plate portion side, The recess is filled with a part of the resin layer. battery.

2. The width of the recess narrows from the opening to the bottom of the recess. The battery of claim 1 .

3. The sealing body is a base layer overlapping the resin layer; Further provided is a protective layer overlapping the base layer on the side opposite to the resin layer, The battery of claim 1 .

4. the sealing body is located outside the exterior member with respect to the side plate portion and the plate member; The battery of claim 1 .

5. When an internal pressure of the exterior member reaches a predetermined pressure equal to or greater than a bonding strength between the first contact surface of the side plate portion and the sealing body, the exterior member ruptures between the first contact surface of the side plate portion and the sealing body. The battery of claim 1 .

6. A method for manufacturing a battery comprising: a box-shaped box member having a side plate portion and accommodating an electrode assembly; a plate member disposed inside a through hole of the side plate portion while being spaced apart from the side plate portion; and a sealing body that contacts the side plate portion and the plate member and seals a gap between the side plate portion and the plate member, a first step of determining a plurality of irradiation positions and an intensity of the laser to be irradiated with a laser at portions of a first contact surface where the side plate portion contacts the sealing body and a second contact surface where the plate member contacts the sealing body, the portions overlapping with the sealing body in a plan view seen from the side plate portion; a second step of irradiating the portion with the laser at the laser intensity determined in the first step at each of the plurality of irradiation positions determined in the first step, thereby forming a plurality of recesses arranged in a matrix in a plan view seen from the side plate portion; a third step of bringing the side plate portion and the plate member into contact with the sealing body and thermally welding them so that a part of the sealing body enters the recess, thereby joining the side plate portion and the plate member to the sealing body, How batteries are manufactured.

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