Welding device and welding method

Abstract

A current collection plate is brought into contact with the inner surface of a bottom plate section (25) of a bottomed cylindrical exterior can (16), and a gas is caused to flow outside the bottom plate section (25) and substantially parallel to the bottom plate section (25). While the gas exhibits such a flowing behavior, the bottom plate section (25) is irradiated with laser light that passes through a region in which the gas flows and that travels in an orthogonal direction substantially orthogonal to the bottom plate section (25) to laser-weld the bottom plate section (25) and the current collection plate together. According to the present disclosure, it is possible to achieve a welding device and a welding method that make it possible to: easily effectively remove a plume produced when laser-welding the bottom plate section (25) and the current collection plate together; and easily achieve good laser-welding between the bottom plate section (25) and the current collection plate.

Description

Welding Device and Welding Method

[0001] The present disclosure relates to a welding device and a welding method for laser welding a current collector plate to the bottom plate portion of a bottomed cylindrical outer can.

[0002] Patent Document 1 describes that one end portion in the height direction of the wound electrode body of a cylindrical battery is formed as a negative electrode core body exposed portion, and the negative electrode core body exposed portion is welded to a current collector plate. Patent Document 1 also describes welding a current collector plate to which the negative electrode core body exposed portion is welded to the bottom plate portion of a bottomed cylindrical outer can.

[0003] Japanese Patent Application Laid-Open No. 2023-115135

[0004] When laser light is irradiated onto the bottom plate portion of a bottomed cylindrical outer can to laser-weld the bottom plate portion and the current collector plate, a plume (vapor of the molten material) of the molten material is generated. This plume is likely to cause welding defects and lead to a decrease in yield. Against this background, although it will be described in detail later, the inventor has found that even when an air flow is made to flow from a direction inclined at an acute angle with respect to the laser light toward the welding location with the intention of removing the plume when irradiating the laser light onto the bottom plate portion from a direction substantially orthogonal to the bottom plate portion, welding defects are likely to occur. Note that this laser welding method using an air flow is not publicly known and is not a prior art. Therefore, an object of the present disclosure is to provide a welding device and a welding method that can easily and effectively remove the plume generated when laser-welding the bottom plate portion of an outer can and the current collector plate, and can easily achieve good laser welding between the bottom plate portion and the current collector plate.

[0005] To solve the above problems, the welding apparatus according to the present disclosure comprises a support base having a support surface for supporting the bottom plate portion of a bottomed cylindrical outer can, and a space defining portion for defining a laser beam emission space from which laser light is emitted toward the bottom plate portion in a direction substantially perpendicular to the support surface, a laser beam emission device for emitting the laser light into the laser beam emission space in the direction perpendicular to the support surface, and a gas discharge device, wherein the support base is provided with a supply passage for which discharged gas from the gas discharge device flows from the outside to the laser beam emission space, including an outlet-side passage portion that extends in a direction substantially parallel to the support surface and communicates with the laser beam emission space at its outlet, and a discharge passage for which at least a portion of the discharged gas flows from the laser beam emission space to the outside, including an inlet that communicates with the laser beam emission space.

[0006] Furthermore, the welding method according to this disclosure involves contacting a current collector plate with the inner surface of the bottom plate portion of a bottomed cylindrical outer can, and while a gas is flowing outside the bottom plate portion substantially parallel to the bottom plate portion, a laser beam passing through the region where the gas is flowing and traveling in a direction substantially perpendicular to the bottom plate portion is irradiated toward the bottom plate portion, thereby laser welding the bottom plate portion and the current collector plate.

[0007] According to the welding apparatus and welding method described herein, it is easier to effectively remove the plume generated when laser welding the bottom plate portion and current collector plate of the outer can, and it is easier to achieve good laser welding of the bottom plate portion and current collector plate.

[0008] This is an axial cross-sectional view of a cylindrical battery that can be manufactured using a welding apparatus and welding method according to one embodiment of the present disclosure. This is a flowchart illustrating an example of the procedure for manufacturing a cylindrical battery. This is a perspective view of an electrode body to which positive electrode leads have been joined. This is a diagram illustrating a laser welding method for the bottom plate portion of the outer casing. This is a diagram illustrating the configuration and operation of the welding apparatus. This is a diagram illustrating a reference example (not a conventional example) welding method. This is a diagram illustrating problems in the reference example welding method. This is a diagram illustrating the effects of the welding apparatus and welding method of the present disclosure.

[0009] The embodiments relating to this disclosure will be described in detail below with reference to the accompanying drawings. Where multiple embodiments or modifications are included below, it is intended from the outset that new embodiments may be constructed by appropriately combining their characteristic features. Furthermore, in the following embodiments, the same reference numerals are used for the same components in the drawings, and redundant explanations are omitted. Also, multiple drawings include schematic diagrams, and the dimensional ratios such as length, width, and height of each component do not necessarily match between different drawings. Furthermore, among the components described below, components not described in the independent claim indicating the highest-level concept are optional components and not essential components. In this specification, the word "omitted" may be used to allow for manufacturing errors (manufacturing variations), and may also be used to describe the general shape of a component. Furthermore, this disclosure is not limited to the embodiments and modifications described below, and various improvements and changes are possible within the scope of the claims of this application and their equivalents.

[0010] Figure 1 is an axial cross-sectional view of a cylindrical battery 10 that can be manufactured using a welding apparatus and welding method according to one embodiment of the present disclosure, and Figure 2 is a flowchart illustrating an example of the procedure for manufacturing the cylindrical battery 10. Hereinafter, the side of the cylindrical battery 10 with the sealing body 17 in the axial direction (height direction) will be referred to as "up," and the side of the outer casing 16 with the bottom plate portion 25 in the axial direction will be referred to as "down." Note that the cylindrical battery 10 shown in Figure 1 is an example of a cylindrical battery 10 that can be manufactured using the welding apparatus and welding method of the present disclosure.

[0011] The welding apparatus and welding method of this disclosure can be used in the manufacture of any cylindrical battery in which one end of the electrode body in the height direction is composed of an electrode core exposed portion in which the electrode core (positive electrode core or negative electrode core) is exposed, the electrode core exposed portion is joined to one end face in the thickness direction of the current collector plate, and the other end face of the current collector plate is welded to the inner surface of the bottom plate portion of a bottomed cylindrical outer casing. Alternatively, the welding apparatus and welding method of this disclosure can also be used in the manufacture of a prismatic battery, such as a consumer prismatic battery, in which the electrode core exposed portion is joined to one end face in the thickness direction of the current collector plate, and the other end face of the current collector plate is welded to the inner surface of the bottom plate portion of a bottomed cylindrical outer casing.

[0012] In the manufacturing procedure for the cylindrical battery (hereinafter simply referred to as "battery") 10 shown in Figure 2, first, in step S1, an electrode assembly 15 (see Figure 1) is manufactured. The electrode assembly 15 includes an electrode body 14, a positive electrode lead 20, and a lower current collector plate 52. Figure 3 is a perspective view of the electrode body 14 to which the positive electrode lead 20 is attached.

[0013] In Figure 3, the positive electrode mixture layer 32 and the negative electrode mixture layer 42 are shown by diagonal hatching. As shown in Figure 3, the electrode body 14 has a long positive electrode 11, a long negative electrode 12, and two long separators 13, and has a wound structure in which the positive electrode 11 and the negative electrode 12 are wound around the separators 13. One or more positive electrode leads 20 are joined to the positive electrode 11, preferably six or more positive electrode leads 20 are joined, and in this embodiment, eight positive electrode leads 20 are joined to the positive electrode 11 at intervals from each other in the longitudinal direction of the positive electrode.

[0014] The negative electrode 12 is formed to be slightly larger than the positive electrode 11 in order to prevent lithium deposition. The negative electrode 12 is formed to be longer than the positive electrode 11 in the winding direction and axial direction. The two separators 13 are formed to be slightly larger than the positive electrode 11 and are arranged to sandwich the positive electrode 11. The separators 13 protrude above the positive electrode 11 and the negative electrode 12, and the negative electrode 12 protrudes below the positive electrode 11 and the separators 13.

[0015] The negative electrode 12 has a negative electrode core body exposed portion 41 at its lower axial end, extending from the inner end to the outer end in the longitudinal direction of the negative electrode, where the negative electrode mixture layer 42 is not provided in the negative electrode core body 40. Therefore, the lower axial end of the electrode body 14 is composed of at least a part of the negative electrode core body exposed portion 41. The negative electrode 12 may constitute the inner end of the electrode body 14. However, generally, the separator 13 extends beyond the inner end of the negative electrode 12, and the inner end of the separator 13 becomes the inner end of the electrode body 14.

[0016] The positive electrode 11 has a positive electrode core 30 and a positive electrode mixture layer 32 formed on both sides of the positive electrode core 30. The positive electrode core 30 can be made of a metal foil that is stable in the potential range of the positive electrode 11, such as aluminum or an aluminum alloy, or a film with the metal arranged on its surface. The positive electrode mixture layer 32 contains a positive electrode active material, a conductive agent, and a binder. The positive electrode 11 can be manufactured, for example, by applying a positive electrode mixture slurry containing a positive electrode active material, a conductive agent, and a binder onto the positive electrode core 30, drying the coating, and then compressing it to form the positive electrode mixture layer 32 on both sides of the positive electrode core 30. The positive electrode is provided with a positive electrode core exposure portion in which the positive electrode core is exposed in a part of the positive electrode width direction. One or more positive electrode leads 20 are joined to the positive electrode core exposure portion by ultrasonic welding or the like.

[0017] The negative electrode 12 has a negative electrode core 40 and a negative electrode mixture layer 42 formed on both sides of the negative electrode core 40. The negative electrode core 40 can be made of a metal foil that is stable in the potential range of the negative electrode 12, such as copper or a copper alloy, or a film with the metal arranged on its surface. The negative electrode mixture layer 42 contains a negative electrode active material and a binder. The negative electrode 12 can be manufactured, for example, by applying a negative electrode mixture slurry containing a negative electrode active material and a binder onto the negative electrode core 40, drying the coating, and then compressing it to form the negative electrode mixture layer 42 on both sides of the negative electrode core 40.

[0018] A porous sheet having ion permeability and insulating properties is used for the separator 13. Specific examples of porous sheets include microporous thin films, woven fabrics, and nonwoven fabrics. The material of the separator 13 is preferably polyethylene, polyolefin resins such as polypropylene, or cellulose. The separator 13 may have either a single-layer structure or a laminated structure. A heat-resistant layer or the like may be formed on the surface of the separator 13.

[0019] Referring to Figures 1 and 3, the electrode body 14 to which the positive electrode lead 20 is joined is pressed against the upper surface of the lower current collector plate 52 so as to tilt the elongated negative electrode core exposed portion 41 radially inward. By irradiating the lower current collector plate 52 with laser light from the lower surface, the negative electrode core exposed portion 41 is laser-welded and joined to the upper surface of the lower current collector plate 52 over a wide area. This completes the production of the electrode body assembly 15.

[0020] Next, in step S2, the lower current collector plate 52 of the electrode assembly 15 is laser-welded to the inner surface of the bottom plate portion 25 of the bottomed cylindrical outer can 16. In this process, first, the bottomed cylindrical outer can 16 shown in Figure 4 is prepared, and the electrode assembly 15 is placed inside the outer can 16 with the lower current collector plate 52 facing downwards. Then, a laser beam is shone from below in the axial direction, which is approximately perpendicular to the bottom plate portion 25, onto the center of the bottom plate portion 25 to laser-weld the lower current collector plate 52 to the bottom plate portion 25.

[0021] Referring to Figure 5 for details, the welding apparatus 55 that performs laser welding comprises a support base 60, a laser beam emission device 80, and a gas discharge device 85. The support base 60 supports the outer container 16 in which the electrode assembly 15 is housed. The support base 60 is a member whose upper surface shape, when viewed from the axial upper side of the support surface 61, is substantially circular. The support base 60 has a laser beam emission space S in its radial center from which the laser beam is emitted toward the bottom plate portion 25 in a direction substantially perpendicular to the support surface 61. In this embodiment, the laser beam emission space S is a through hole provided in the radial center of the support base 60, and the inner circumferential surface 62 of the through hole is a space definition portion that defines the laser beam emission space S.

[0022] The outer container 16 is supported on the support surface 61 of the support base 60 such that the extension of its central axis substantially coincides with the central axis of the support base 60. The gas discharge device 85 is composed of an air pump or the like. Inside the support base 60, there is a supply passage 67 through which the discharged gas (compressed air) from the gas discharge device 85 flows from the outside to the laser beam emission space S, including an outlet-side passage 65 that extends in a direction substantially parallel to the support surface 61 and communicates with the laser beam emission space S at an outlet 64.

[0023] Furthermore, the support base 60 is provided with an outlet passage 69, which includes an inlet 68 communicating with the laser beam emission space, through which at least a portion of the discharged gas flows from the laser beam emission space S to the outside. The discharged air is discharged radially from the support base 60 into the laser beam emission space S from the outlet 64 of the supply passage 67. The inlet 68 of the outlet passage 69 is oriented radially from the support base 60. The outlet 64 and the inlet 68 include portions located on a straight line extending substantially radially, and portions that are radially opposite to each other.

[0024] As shown in Figure 5, the discharged air from the gas discharge device 85 flows into the supply passage 67 from the inlet 71 and is discharged radially from the outlet 64 toward the laser beam emission space S in a direction substantially parallel to the support surface 61. At least a portion of the discharged air then crosses the laser beam emission space S substantially radially, flows into the discharge passage 69 from the inlet 68, and is discharged to the outside from the outlet 73 of the discharge passage 69.

[0025] The laser beam emitter 80 emits laser light axially towards the radial center of the bottom plate portion 25 of the outer can 16 supported on the support surface 61, with at least a portion of the discharged air traversing the laser beam emission space S in the radial direction. The lower current collector plate 52 is laser-welded to the bottom plate portion 25 by the emission of laser light while the discharged air is flowing.

[0026] Referring to Figure 1, in step S3, after the upper insulating plate 18 is housed inside the outer can 16, a grooved portion 22 is formed in the outer can 16. The upper insulating plate 18 has a through hole in its center. The upper insulating plate 18 is housed inside the outer can 16 with the tip of the positive electrode lead 20 passing through the through hole and positioned above the upper insulating plate 18. Subsequently, an annular grooved portion 22 is provided in the outer can 16 by spinning a part of the cylindrical portion 39 of the outer can to create a recess radially inward along its entire circumference.

[0027] In the following step S4, after housing the annular gasket 28 inside the outer can 16, the positive electrode lead 20 is joined to the sealing body 17. More specifically, after housing the annular gasket 28 inside the outer can 16, the positive electrode lead 20 is laser-welded to the upper current collector plate 50. More specifically, the positive electrode lead 20 is bent from the positive electrode 11 through the through hole 50a in the upper current collector plate 50 so as to follow the upper surface of the upper current collector plate 50. The tip of each positive electrode lead 20 is sandwiched between the upper surface of the upper current collector plate 50 and the lower surface of the metal plate 51. Each positive electrode lead 20 is joined to the upper surface of the upper current collector plate 50. The upper current collector plate 50 and the metal plate 51 are also joined, and each positive electrode lead 20 is also joined to the metal plate 51. These joints can be achieved, for example, by laser welding the metal plate 51 by irradiating it axially with a laser beam from above while the tip of each positive electrode lead 20 is sandwiched between the upper current collector plate 50 and the metal plate 51. By laser welding the tip of the positive electrode lead 20 while it is sandwiched between the upper current collector plate 50 and the metal plate 51, the positive electrode lead 20 can be reliably and easily welded to the upper current collector plate 50 and joined.

[0028] The sealing body 17 comprises an upper current collector plate 50, a metal plate 51, and a terminal cap 27. The sealing body 17 has a laminated portion 57 on its outer edge in which the terminal cap 27 and the upper current collector plate 50 are stacked. By irradiating the laminated portion 57 from above with laser light, the terminal cap 27 and the upper current collector plate 50 are laser-welded and electrically connected. The annular upper surface of the upper current collector plate 50 has an annular recess 53 that is radially inward from the laminated portion 57. Because the upper surface of the upper current collector plate 50 has a recess 53 that is recessed downward, a space is provided between the terminal cap 27 and the recess 53 of the upper current collector plate 50. Each positive electrode lead 20 is joined to the upper current collector plate 50 within the recess 53. In this way, the positive electrode leads 20 are joined to the sealing body 17.

[0029] In the following step S5, the electrolyte is placed inside the outer can 16. The electrolyte may be an aqueous electrolyte or a non-aqueous electrolyte. The electrolyte may also be a liquid electrolyte (electrolyte solution) or a solid electrolyte. In the following step S6, the upper end of the outer can is crimped. Specifically, the sealing body 17 is placed on the grooved portion 22 and crimped to the opening of the outer can 16 via a resin gasket 28. The shoulder portion 29 is formed when the upper end of the cylindrical portion 39 is bent radially inward and crimped to the outer edge of the sealing body 17, and extends radially inward at the upper end of the outer can 16.

[0030] The internal space of the battery 10 is sealed by an annular gasket 28 that seals the space between the outer casing 16 and the sealing body 17. The gasket 28 is sandwiched between the outer casing 16 and the sealing body 17, insulating the sealing body 17 from the outer casing 16. The gasket 28 serves as a sealing material to maintain airtightness inside the battery and as an insulating material to insulate the outer casing 16 and the sealing body 17. The terminal cap 27 electrically connected to the positive electrode lead 20 becomes the positive electrode terminal, and the outer casing 16 electrically connected to the negative electrode core exposed portion 41 via the lower current collector plate 52 becomes the negative electrode terminal.

[0031] The battery 10 shown in Figure 1 has a thin, easily breakable portion 25a on the bottom plate portion 25 of the outer casing 16. The easily breakable portion 25a is formed, for example, by marking the lower surface of the bottom plate portion 25 with a circular or C-shaped mark. By providing the easily breakable portion 25a on the bottom plate portion 25, when the battery 10 overheats abnormally, the easily breakable portion 25a will break, allowing the high-temperature gas inside the battery 10 to be released to the outside, thereby increasing the safety of the battery 10. The thin, easily breakable portion may also be provided on the terminal cap. When step S6 is completed, the manufacturing of the battery 10 is finished.

[0032] Next, the effects of the technology disclosed herein will be explained. When laser welding the bottom plate portion and the current collector plate of a bottomed cylindrical outer can by irradiating the bottom plate portion with laser light, a plume of molten material (vapor of molten material) is generated. This plume is prone to causing welding defects and leads to a decrease in yield. Against this backdrop, the inventors of this invention have found that, as shown in Figure 6, when irradiating the bottom plate portion 25 with laser light from a direction substantially perpendicular to the bottom plate portion 25, even if an airflow is blown towards the welding area from a direction inclined at an acute angle to the laser light, as indicated by arrow A, welding defects cannot be effectively suppressed.

[0033] The inventors of this case surmise that the reason for this is that, with such air blowing, turbulent airflow 91 is generated near the welding site, and as shown in Figure 7, the generation of plume 93 rising in a direction substantially perpendicular to the base material, the bottom plate 25, cannot be effectively excluded. As a result, the input of laser light to the welding site varies from one piece to another and becomes uneven, causing excessive bulging 92 or sharp depressions in the bead 94, which is the welding trajectory.

[0034] In contrast, according to the welding apparatus 55 of this disclosure, while the gas is flowing outside the bottom plate portion approximately parallel to the bottom plate portion 25, laser light is irradiated toward the bottom plate portion 25 in a direction perpendicular to the bottom plate portion 25 as it passes through the region where the gas is flowing. Therefore, as shown in Figure 8, the rising of the plume 93 in a direction approximately perpendicular to the bottom plate portion 25 can be effectively suppressed, and uniform input of laser light to the welding area, independent of individual differences, can be easily achieved. Thus, it is easier to achieve an appropriate bead 98 rise 99 and effectively suppress welding defects.

[0035] In Figures 7 and 8, the welding direction indicates the scanning direction of the laser beam. It is preferable that the opening area of ​​the outlet 64 be smaller than the opening area of ​​the inlet 68, as this allows for a higher flow velocity of compressed air discharged into the laser beam emission space S and a wider flow path for discharging the plume 93. Furthermore, to make this effect more pronounced, it is preferable to make the opening area of ​​the outlet 64 smaller than the opening area of ​​the inlet 68, and even further, to make the opening area of ​​the outlet 64 5.0 mm². ２ 50.0 mm ２ It is less than 5.0 mm in diameter at the entrance 68.２ Larger, 50.0 mm ２ The following is preferable:

[0036] It is preferable that the outlet 64 and inlet 68 include portions located on a straight line extending substantially parallel to the support surface 61, as this facilitates the generation of a smooth, unidirectional flow in the laser beam emission space S that is rectified substantially parallel to the support surface 61, and further effectively suppresses the generation of plumes 93 in a direction substantially perpendicular to the bottom plate portion 25.

[0037] In order to effectively suppress the rising of the plume 93 in a direction substantially perpendicular to the bottom plate portion 25 and to effectively suppress welding defects, it is preferable that the flow rate of the space discharge gas discharged from the supply passage 67 to the laser beam emission space S is 10 L / min or more and 100 L / min or less, and the flux of the space discharge gas is 10 m / sec or more and 100 m / sec or less. Furthermore, in order to efficiently achieve uniform input of laser light to the welding location regardless of individual differences, it is preferable that the aperture diameter of the laser beam emission portion 81 of the laser beam emission device 80 is 1.0 mm or more and 10.0 mm or less.

[0038] Furthermore, the welding apparatus of this disclosure may have the following configurations: Configuration 1: A welding apparatus comprising: a support base having a support surface for supporting the bottom plate portion of a bottomed cylindrical outer can, and a space defining portion for defining a laser beam emission space from which laser light is emitted toward the bottom plate portion in a direction substantially perpendicular to the support surface; a laser beam emission device for emitting the laser light into the laser beam emission space in the direction perpendicular to the support surface; and a gas discharge device, wherein a supply passage is provided inside the support base, including an outlet-side passage portion extending in a direction substantially parallel to the support surface and communicating with the laser beam emission space at its outlet, through which the discharged gas from the gas discharge device flows from the outside to the laser beam emission space; and a discharge passage is provided inside the support base, including an inlet communicating with the laser beam emission space, through which at least a portion of the discharged gas flows from the laser beam emission space to the outside. Configuration 2: The welding apparatus according to Configuration 1, wherein the opening area of ​​the outlet is smaller than the opening area of ​​the inlet. Configuration 3: The opening area of ​​the outlet is 5.0 mm ２ 50.0 mm ２It is less than 5.0 mm, and the diameter of the entrance is 5.0 mm ２ Larger, 50.0 mm ２ The welding apparatus according to configuration 2, which is as follows: Configuration 4: The welding apparatus according to any one of configurations 1 to 3, wherein the outlet and the inlet are located on a straight line extending substantially parallel to the support surface. Configuration 5: The welding apparatus according to any one of configurations 1 to 4, wherein the flow rate of the space discharge gas discharged from the supply passage to the laser beam emission space is 10 L / min or more and 100 L / min or less, and the flux of the space discharge gas is 10 m / sec or more and 100 m / sec or less. Configuration 6: The welding apparatus according to any one of configurations 1 to 5, wherein the aperture diameter of the laser beam emission section of the laser beam emission device is 1.0 mm or more and 10.0 mm or less.

[0039] 10 Cylindrical battery, 11 Positive electrode, 12 Negative electrode, 13 Separator, 14 Electrode body, 15 Electrode body assembly, 16 Outer can, 17 Sealing body, 18 Upper insulating plate, 20 Positive electrode lead, 22 Grooved section, 25 Bottom plate section, 25a Easily breakable section, 27 Terminal cap, 28 Gasket, 29 Shoulder section, 30 Positive electrode core, 32 Positive electrode mixture layer, 39 Cylindrical section, 40 Negative electrode core, 41 Negative electrode core exposed section, 42 Negative electrode mixture layer, 50 Upper current collector plate, 50a Through hole, 51 Metal plate, 52 Lower current collector plate, 55 Welding device, 57 Laminated section, 60 Support base, 61 Support surface, 62 Inner surface, S Laser beam emission space, 64 Outlet of supply passage, 65 Outlet side passage section, 67 Supply passage, 68 Inlet of discharge passage, 69 Discharge passage, 71 Inlet of supply passage, 73 Outlet of supply passage, 80 Laser beam emission device, 81 Laser beam emission section, 85 Gas discharge device, 91 Turbulence, 92, 99 Bump, 93 Plume, 94, 98 Bead.

Claims

1. A welding apparatus comprising: a support base having a support surface for supporting the bottom plate portion of a bottomed cylindrical outer can, and a space defining portion for defining a laser beam emission space from which laser light is emitted toward the bottom plate portion in a direction substantially perpendicular to the support surface; a laser beam emission device for emitting the laser light into the laser beam emission space in the direction perpendicular to the support surface; and a gas discharge device, wherein a supply passage is provided inside the support base, including an outlet-side passage portion that extends in a direction substantially parallel to the support surface and communicates with the laser beam emission space at its outlet, through which discharged gas from the gas discharge device flows from the outside to the laser beam emission space; and a discharge passage is provided inside the support base, including an inlet that communicates with the laser beam emission space, through which at least a portion of the discharged gas flows from the laser beam emission space to the outside.

2. The welding apparatus according to claim 1, wherein the opening area of ​​the outlet is smaller than the opening area of ​​the inlet.

3. The opening area of ​​the outlet is 5.0 mm². ２ 50.0 mm ２ It is less than 5.0 mm, and the diameter of the entrance is 5.0 mm ２ Larger, 50.0 mm ２ The welding apparatus according to claim 2, which is as follows:

4. The welding apparatus according to any one of claims 1 to 3, wherein the outlet and the inlet include portions located on a straight line extending substantially parallel to the support surface.

5. The welding apparatus according to any one of claims 1 to 3, wherein the flow rate of the space discharge gas discharged from the supply passage to the laser beam emission space is 10 L / min or more and 100 L / min or less, and the flux of the space discharge gas is 10 m / sec or more and 100 m / sec or less.

6. The welding apparatus according to any one of claims 1 to 3, wherein the aperture diameter of the laser light emitting section of the laser light emitting apparatus is 1.0 mm or more and 10.0 mm or less.

7. A welding method for laser welding a bottom plate and a current collector plate, wherein a current collector plate is brought into contact with the inner surface of the bottom plate of a bottomed cylindrical outer can, and gas is flowed outside the bottom plate substantially parallel to the bottom plate, and a laser beam passing through the area where the gas is flowing and traveling in a direction substantially perpendicular to the bottom plate is irradiated toward the bottom plate.

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