Joining method, power storage device, and method for manufacturing same

Abstract

The invention relates to a bonding method, an electricity storage device and a manufacturing method thereof. Provided is a bonding method in which welding sputter is less likely to remain. The disclosed joining method comprises: a laser welding step for irradiating a boundary portion between a first metal member and a second metal member with laser light to form a welded joint; and an etching step for forming a plurality of substantially circular recesses in the surface and the peripheral edge of the welded joint by irradiating the surface and the peripheral edge of the welded joint with energy rays at an output lower than that of the laser welding step.

Description

Technical Field

[0001] This invention relates to a connection method and an energy storage device, as well as a method of manufacturing the same. Background Technology

[0002] In the past, in the manufacturing process of energy storage devices, a first metal component and a second metal component were joined by laser welding. Examples of related prior art include International Patent Publication No. 2010 / 131298, Japanese Patent No. 6885072, and Japanese Patent Application Publication No. 2016-140877.

[0003] Prior art literature

[0004] Patent documents

[0005] Patent Document 1: International Publication No. 2010 / 131298

[0006] Patent Document 2: Japanese Patent No. 6885072

[0007] Patent Document 3: Japanese Patent Application Publication No. 2016-140877 Summary of the Invention

[0008] According to the inventors of this application, when metal components are welded together using a laser, the high-temperature molten metal generated at the welding point sometimes turns into microparticles (so-called welding spatter), which randomly scatter onto the surface and periphery of the weld joint. If welding spatter remains, it can cause adverse conditions such as short circuits. Therefore, there is a need to efficiently remove welding spatter after laser welding.

[0009] The present invention was made in view of the above circumstances, and its main objective is to provide a bonding method in which weld spatter is difficult to leave residue.

[0010] According to the present invention, a joining method is provided, wherein the joining method includes: a laser welding process, wherein the laser welding process irradiates a boundary portion of a first metal component and a second metal component with a laser to form a welded joint; and an etching process, wherein the etching process irradiates the surface and periphery of the welded joint with an energy beam at a lower output than that of the laser welding process, thereby forming a plurality of generally circular recesses on the surface and periphery of the welded joint.

[0011] In this invention, during the etching process, energy rays are irradiated onto the surface and periphery of the weld joint. This efficiently removes weld spatter that has scattered to random locations during the laser welding process. Consequently, weld spatter residue is reduced. Attached Figure Description

[0012] Figure 1 This is a perspective view schematically illustrating an embodiment of an energy storage device.

[0013] Figure 2 It is along Figure 1 A schematic longitudinal section view of line II-II.

[0014] Figure 3 It is a schematic three-dimensional view of the combined sealing plate and electrode assembly.

[0015] Figure 4 This is a schematic diagram showing the structure of a wound electrode.

[0016] Figure 5 This is a schematic perspective view of the sealing plate assembly.

[0017] Figure 6 It is Figure 5 A 3D view of the sealing plate turned upside down.

[0018] Figure 7 yes Figure 5 Sectional view along line VII-VII.

[0019] Figure 8 It is shown schematically. Figure 6 A magnified top view of the area near the welded joint.

[0020] Figure 9 yes Figure 8 A magnified view of the roughened portion.

[0021] Figure 10 yes Figure 9 XX-line sectional view.

[0022] Figure 11 It involves variations and Figure 8 A fairly accurate diagram.

[0023] Figure 12 Images (A) through (D) are observation images of the vicinity of the welded joint involved in the embodiments. Detailed Implementation

[0024] Hereinafter, preferred embodiments of the technology disclosed herein will be described with reference to the accompanying drawings. Furthermore, matters other than those specifically mentioned in this specification that are essential for implementing the invention (e.g., the general structure and manufacturing process of an energy storage device that do not constitute a feature of the invention) can be understood as design considerations by those skilled in the art based on prior art. The present invention can be implemented based on the disclosure herein and common technical knowledge in the field.

[0025] Furthermore, as one embodiment of the joining method disclosed herein, the following description will use a method for manufacturing an energy storage device comprising a first metal member and a second metal member as examples, but it is not intended to limit the application of the joining method disclosed herein to energy storage devices. Additionally, the expression "A~B" indicating a range in this specification includes meanings of A and below, and meanings of "greater than A" and "less than B".

[0026] <Electric Storage Devices>

[0027] First, the structure of the energy storage device manufactured by the manufacturing method disclosed herein will be described. Furthermore, in this specification, "energy storage device" refers to any device capable of repeated charging and discharging by moving charge carriers between the positive and negative electrodes via an electrolyte. The electrolyte can be any of a liquid electrolyte (electrolyte), a gel electrolyte, or a solid electrolyte. Energy storage devices include secondary batteries such as lithium-ion batteries or nickel-metal hydride batteries, and capacitors such as lithium-ion capacitors or double-layer capacitors.

[0028] Figure 1 This is a three-dimensional view of the energy storage device 100. Figure 2 It is along Figure 1 A schematic longitudinal sectional view along line II-II. Furthermore, in the following description, the symbols L, R, F, Rr, U, and D in the figures represent left, right, front, back, top, and bottom, respectively; and the symbols X, Y, and Z represent the short side direction of the energy storage device 100, the long side direction orthogonal to the aforementioned short side direction, and the up-down direction orthogonal to both the aforementioned short side direction and the long side direction, respectively. However, these are merely for illustrative purposes and do not impose any limitations on the arrangement of the energy storage device 100.

[0029] like Figure 2 As shown, the energy storage device 100 includes a housing 10, an electrode assembly 20, a positive terminal 30, a negative terminal 40, a positive current collector 50, and a negative current collector 60. Although not shown in the figure, the energy storage device 100 also includes a non-aqueous electrolyte. The energy storage device 100 is configured to house the electrode assembly 20 and a non-aqueous electrolyte (not shown) within the housing 10. Here, the energy storage device 100 is a non-aqueous electrolyte secondary battery. More specifically, it is a lithium-ion secondary battery.

[0030] The housing 10 is a frame that houses the electrode assembly 20 and the non-aqueous electrolyte. Here, the housing 10 has a flat, bottomed rectangular (square) shape. The material of the housing 10 can be the same as conventionally used materials, without particular limitation. The housing 10 is preferably made of metal, and more preferably of aluminum, aluminum alloy, iron, or iron alloy. Figure 2As shown, the housing 10 includes: a housing body 12 having an opening 12h; and a sealing plate (cover) 14 that seals the opening 12h.

[0031] like Figure 1 As shown, the housing body 12 includes: a generally rectangular bottom wall 12a; a pair of long side walls 12b extending from the long side of the bottom wall 12a and facing each other; and a pair of short side walls 12c extending from the short side of the bottom wall 12a and facing each other. The area of ​​the short side walls 12c is smaller than the area of ​​the long side walls 12b. Electrode groups 20 and a non-aqueous electrolyte are housed inside the housing body 12. Furthermore, in this specification, "generally rectangular" includes not only a perfect rectangle (rectangle) but also shapes such as those where the corners connecting the long and short sides of a rectangle are R-shaped, or shapes with cutouts at the corners.

[0032] The sealing plate 14 is a plate-shaped member with a specified thickness. The sealing plate 14 is installed on the housing body 12 to block the opening 12h of the housing body 12. The sealing plate 14 faces the bottom wall 12a of the housing body 12. The sealing plate 14 is generally rectangular in plan view. The housing 10 is integrated by joining (e.g., welding) the sealing plate 14 to the periphery of the opening 12h of the housing body 12. The housing 10 is hermetically sealed (closed).

[0033] like Figure 2 As shown, the sealing plate 14 is provided with an injection hole 15, a gas discharge valve 17, and two terminal outlet holes 18 and 19. The injection hole 15 is configured to inject a non-aqueous electrolyte into the interior of the housing 10 after the sealing plate 14 is assembled onto the housing body 12. The injection hole 15 is sealed by a sealing member 16. The gas discharge valve 17 is configured to rupture when the pressure inside the housing 10 reaches a specified value, thereby venting the gas inside the housing 10 to the outside. The terminal outlet holes 18 and 19 are respectively formed at both ends of the sealing plate 14 in the Y direction along its long side. The terminal outlet holes 18 and 19 penetrate the sealing plate 14 in the Z direction along its vertical side. The terminal outlet holes 18 and 19 are cylindrical in shape. The terminal outlet holes 18 and 19 each have an inner diameter that allows the positive terminal 30 and the negative terminal 40 to be inserted before the sealing plate 14 is installed (before riveting). For example, the terminal lead hole 18 is formed to be smaller than the shaft portion 30a of the positive terminal 30 before riveting.

[0034] Figure 3This is a perspective view schematically showing the combination of the sealing plate 14 (specifically, the sealing plate assembly described later) and the electrode group 20. Here, the electrode group 20 has three electrode bodies 20a, 20b, and 20c. However, the number of electrode bodies disposed inside the housing 10 is not particularly limited; it can be one or more (two or more). Furthermore, the configuration of the electrode bodies 20a, 20b, and 20c is not particularly limited and can be the same as before.

[0035] Figure 4 This is a schematic diagram showing the configuration of electrode body 20a. Furthermore, the following detailed description uses electrode body 20a as an example, but electrode bodies 20b and 20c can also have the same configuration. Electrode body 20a has a positive electrode 22 and a negative electrode 24. The positive electrode 22 and the negative electrode 24 are examples of the first and second electrodes disclosed herein. Here, electrode body 20a is a flat, wound electrode body, formed by layering a strip-shaped positive electrode 22 and a strip-shaped negative electrode 24 via two strip-shaped diaphragms 26 and winding them around a winding axis WL. However, electrode bodies 20a, 20b, and 20c can also be laminated electrode bodies, formed by overlapping square (typically rectangular) positive electrodes and square (typically rectangular) negative electrodes in an insulated state.

[0036] like Figure 2 , Figure 4 It can be seen that the electrode body 20a is arranged inside the housing 10 with the winding axis WL parallel to the long side direction Y. In other words, the electrode body 20a is arranged inside the housing 10 with the winding axis WL parallel to the bottom wall 12a and orthogonal to the short side wall 12c. Figure 2 As shown, the energy storage device 100 has a so-called horizontal tab structure with the positive tab group 23 and the negative tab group 25 positioned to the left and right of the electrode body group 20. However, the energy storage device 100 may also have a so-called upper tab structure with the positive tab group 23 and the negative tab group 25 positioned vertically above and below the electrode body group 20.

[0037] Here, as Figure 4 As shown, the positive electrode 22 includes: a positive current collector 22c; and a positive active material layer 22a and a positive protective layer 22p fixed on at least one surface of the positive current collector 22c. However, the positive protective layer 22p is not essential and can be omitted in other embodiments. The positive current collector 22c is strip-shaped. The positive current collector 22c is made of conductive metals such as aluminum, aluminum alloy, nickel, and stainless steel. Here, the positive current collector 22c is a metal foil, specifically an aluminum foil.

[0038] At one end of the long side Y of the positive current collector 22c ( Figure 4The left end of the electrode is provided with multiple positive electrode tabs 22t. These multiple positive electrode tabs 22t are convex, facing the long side Y direction (…). Figure 4 (Left side) protrudes. Multiple positive electrode tabs 22t are spaced apart (intermittently) along the length of the positive electrode 22. Here, the positive electrode tabs 22t are part of the positive current collector 22c and are made of metal foil (aluminum foil). The positive electrode tabs 22t are the portions of the positive current collector 22c where the positive active material layer 22a and the positive protective layer 22p are not formed (exposed portion of the current collector). However, the positive electrode tabs 22t can also be components separate from the positive current collector 22c. Multiple positive electrode tabs 22t are located at one end in the long side direction Y ( Figure 4 (Left end) layering, such as Figure 2 As shown, a positive electrode tab group 23 is formed. The positive electrode tab group 23 is electrically connected to the positive terminal 30 via the positive electrode current collector 50. A second positive electrode current collector 52, which will be described later, is attached to the positive electrode tab group 23.

[0039] like Figure 4 As shown, the positive electrode active material layer 22a is arranged in a strip shape along the length direction of the strip-shaped positive electrode current collector 22c. The positive electrode active material layer 22a contains a positive electrode active material (such as a lithium transition metal composite oxide, such as a lithium nickel cobalt manganese composite oxide) that can reversibly adsorb and release charge carriers. The positive electrode active material layer 22a may also contain any components other than the positive electrode active material, such as conductive materials, binders, and various additives.

[0040] like Figure 4 As shown, the positive electrode protective layer 22p is provided in the long side direction Y at the boundary between the positive electrode current collector 22c and the positive electrode active material layer 22a. Here, the positive electrode protective layer 22p is provided at one end of the positive electrode current collector 22c in the long side direction Y ( Figure 4 (At the left end). The positive electrode protective layer 22p is arranged in a strip along the positive electrode active material layer 22a. The positive electrode protective layer 22p contains inorganic fillers (e.g., alumina). The positive electrode protective layer 22p may also contain any components other than inorganic fillers, such as conductive materials, binders, various additives, etc.

[0041] Here, as Figure 4 As shown, the negative electrode 24 has: a negative electrode current collector 24c; and a negative electrode active material layer 24a fixed on at least one surface of the negative electrode current collector 24c. The negative electrode current collector 24c is strip-shaped. The negative electrode current collector 24c is made of conductive metals such as copper, copper alloy, nickel, and stainless steel. Here, the negative electrode current collector 24c is a metal foil, specifically a copper foil.

[0042] At one end of the long side Y of the negative current collector 24c ( Figure 4The right end of the electrode is provided with multiple negative electrode tabs 24t. These multiple negative electrode tabs 24t are convex, facing the long side Y direction (…). Figure 4 The right side of the negative electrode 24 protrudes. Multiple negative electrode tabs 24t are spaced apart (intermittently) along the length of the negative electrode 24. Here, the negative electrode tabs 24t are part of the negative electrode current collector 24c and are made of metal foil (copper foil). The negative electrode tabs 24t are the portions of the negative electrode current collector 24c where the negative electrode active material layer 24a is not formed (exposed portion of the current collector). However, the negative electrode tabs 24t can also be components separate from the negative electrode current collector 24c. Multiple negative electrode tabs 24t are located at one end in the long side direction Y (… Figure 4 (The right end) layering, such as Figure 2 As shown, a negative electrode tab group 25 is formed. The negative electrode tab group 25 is electrically connected to the negative terminal 40 via a negative electrode current collector 60. A second negative electrode current collector 62, which will be described later, is attached to the negative electrode tab group 25.

[0043] like Figure 4 As shown, the negative electrode active material layer 24a is arranged in a strip shape along the length of the strip-shaped negative electrode current collector 24c. The negative electrode active material layer 24a contains a negative electrode active material (such as carbon materials like graphite) capable of reversibly adsorbing and discharging charge carriers. The negative electrode active material layer 24a may further contain any components other than the negative electrode active material, such as binders, dispersants, and various additives.

[0044] The separator 26 is a component that insulates the positive electrode active material layer 22a of the positive electrode 22 from the negative electrode active material layer 24a of the negative electrode 24. Suitable materials for the separator 26 include, for example, a porous resin sheet made of polyolefin resins such as polyethylene (PE) or polypropylene (PP). Alternatively, functional layers such as an adhesive layer containing an adhesive and a heat resistance layer (HRL) containing inorganic fillers may be provided on the surface of the separator 26.

[0045] The non-aqueous electrolyte can be the same as before, without any particular limitations. A non-aqueous electrolyte typically comprises a non-aqueous solvent and a supporting salt. Examples of non-aqueous solvents include carbonates such as ethylene carbonate, dimethyl carbonate, and ethyl methyl carbonate. Examples of supporting salts are fluorinated lithium salts such as LiPF6. However, in other embodiments, for the energy storage device 100, in addition to a non-aqueous electrolyte, an aqueous electrolyte, a gel electrolyte, or a solid electrolyte (solid electrolyte) may also be used as the electrolyte.

[0046] Figure 5 This is a schematic perspective view of the sealing plate assembly. Figure 6 It is Figure 5 A three-dimensional view of the sealing plate 14 turned over. Figure 6The inner side of the housing body 12 of the sealing plate 14 is shown. Here, the sealing plate assembly is an assembly of the sealing plate 14, the positive terminal 30, the negative terminal 40, the first positive current collector 51 of the positive current collector 50, the first negative current collector 61 of the negative current collector 60, two resin components 70, and two gaskets 90. In the sealing plate assembly, the positive terminal 30, gaskets 90, the first positive current collector 51 of the positive current collector 50, and resin components 70 are integrated onto the sealing plate 14 by riveting the positive terminal 30 and welding it to the first positive current collector 51. Similarly, by riveting the negative terminal 40 and welding it to the negative first current collector 61, the negative terminal 40, the gasket 90, the negative first current collector 61 of the negative current collector 60 and the resin component 70 are integrated onto the sealing plate 14.

[0047] like Figure 5 As shown, the positive terminal 30 and the negative terminal 40 are respectively mounted on the sealing plate 14. The positive terminal 30 is located on one side of the long side Y direction of the sealing plate 14. Figure 5 (Left side). The negative terminal 40 is positioned on the other side of the long side Y direction of the sealing plate 14 ( Figure 5 (The right side). In addition, the following detailed explanation will take the positive terminal 30 side as an example, while the negative terminal 40 side can also have the same configuration.

[0048] like Figure 2 As shown, the positive terminal 30 is electrically connected inside the housing 10 to the positive terminals 22 (specifically, the positive electrode tab group 23) of the electrode bodies 20a, 20b, and 20c via the positive current collector 50. The positive terminal 30 is electrically connected to the first positive current collector 51 of the positive current collector 50 by riveting (mechanical fastening) and welding. The positive terminal 30 is preferably made of metal, and more preferably of aluminum or an aluminum alloy. The positive terminal 30 is an example of a first metal component disclosed herein.

[0049] Figure 7 yes Figure 5 The sectional view along line VII-VII is a schematic, enlarged sectional view showing a portion near the positive end 30. Additionally, in Figure 7 In the diagram, the central axis CL of the positive terminal 30 is indicated by a single-dotted line. For example... Figure 7 As shown, the positive terminal 30 is inserted through the terminal lead-out hole 18 of the sealing plate 14 and extends from the inside of the sealing plate 14 to the outside. The positive terminal 30 has: a shaft portion 30a; a flange portion 30f that expands in diameter from the upper end of the shaft portion 30a; and a riveting portion 30c provided at the lower end of the shaft portion 30a.

[0050] like Figure 7As shown, the shaft portion 30a extends vertically in the Z direction along the central axis CL. The shaft portion 30a is inserted through the terminal lead-out hole 18 of the sealing plate 14 and the through hole 51h of the positive electrode first current collector 51 (see reference). Figure 6 In this context, the shaft portion 30a is cylindrical. The lower end of the shaft portion 30a, that is, the end opposite to the side where the flange portion 30f is located, is hollow.

[0051] like Figure 7 As shown, the flange portion 30f connects to the upper end of the shaft portion 30a and extends upward. The flange portion 30f is larger than the shaft portion 30a. The flange portion 30f is larger than the terminal lead-out hole 18 of the sealing plate 14. The flange portion 30f protrudes from the terminal lead-out hole 18 toward the outside of the housing 10 (specifically, the outer surface of the sealing plate 14). Here, the flange portion 30f is circular when viewed from above. Here, the flange portion 30f is approximately cylindrical in shape. The axis of the flange portion 30f coincides with the axis of the shaft portion 30a.

[0052] like Figure 7 As shown, the riveting part 30c is provided at the end of the housing 10 inside the shaft part 30a. Figure 7 The lower end of the shaft portion 30a is provided at the periphery of the terminal lead-out hole 18 of the sealing plate 14. The riveting portion 30c is the part where the lower end of the shaft portion 30a is expanded by riveting when the positive terminal 30 is installed on the sealing plate 14. Preferably, the riveting portion 30c is arranged axially symmetrically with respect to the central axis CL of the positive terminal 30. As a result, even if vibration or impact is applied when using the energy storage device 100, the electrical connection between the positive terminal 30 and the positive current collector 50 can be stably maintained, and the conductivity reliability of the positive terminal 30 can be improved. Here, the riveting portion 30c is annular (e.g., circular) when viewed from above. The riveting portion 30c is provided all around the periphery of the terminal lead-out hole 18.

[0053] like Figure 7 As shown, the gasket 90 is an insulating member disposed between the sealing plate 14 and the positive terminal 30. Here, the gasket 90 functions to insulate the sealing plate 14 and the positive terminal 30 and to lock the terminal lead-out hole 18. The gasket 90 is made of a resin material that has electrical insulation properties and can be elastically deformed, such as fluorinated resins like perfluoroalkoxy fluoropolymer (PFA), polyphenylene sulfide resin (PPS), aliphatic polyamide, etc. Here, the gasket 90 has a cylindrical portion 90a and a base portion 90b.

[0054] The cylindrical portion 90a is the part that prevents the sealing plate 14 from directly contacting the shaft portion 30a of the positive terminal 30. The cylindrical portion 90a is hollow and cylindrical in shape. The cylindrical portion 90a has a through hole in the vertical direction Z at a position corresponding to the terminal lead-out hole 18 of the sealing plate 14. The through hole has an inner diameter that allows the shaft portion 30a of the positive terminal 30 to be inserted before riveting. The cylindrical portion 90a is inserted into the terminal lead-out hole 18 of the sealing plate 14. The base portion 90b is the part that prevents the sealing plate 14 from directly contacting the flange portion 30f of the positive terminal 30. The base portion 90b is connected to the upper end of the cylindrical portion 90a. Here, the base portion 90b is arranged in an annular shape to surround the terminal lead-out hole 18 of the sealing plate 14. The base 90b is sandwiched between the lower surface of the flange 30f of the positive terminal 30 and the sealing plate 14, and is compressed in the vertical Z direction by riveting.

[0055] like Figure 2 As shown, the positive current collector 50 forms a conductive path that electrically connects the positive electrode tab group 23 (positive electrode 22) composed of multiple positive electrode tabs 22t to the positive terminal 30. The positive current collector 50 may also be made of the same type of metal as the positive current collector 22c, such as aluminum, aluminum alloy, nickel, stainless steel, or other conductive metals. More preferably, the positive current collector 50 is made of aluminum or an aluminum alloy. Here, the positive current collector 50 includes: a first positive current collector 51 extending along the inner surface of the sealing plate 14 (also see...). Figure 6 ); and the positive electrode second current collector 52 extending along the short sidewall 12c of the housing body 12 (also see Figure 3 ).

[0056] like Figure 7 As shown, the first positive current collector 51 is fixed to the sealing plate 14 by means of a riveting part 30c and a welding joint J. Figure 6 As shown, the first positive electrode current collector 51 is approximately L-shaped. The first positive electrode current collector 51 can be constructed by bending a single component, for example, through stamping, or by integrating multiple components through welding. The first positive electrode current collector 51 has: a first portion 511 extending horizontally along the inner surface of the sealing plate 14; and an end portion extending from the long side direction Y of the first portion 511. Figure 6 The second part 512 extends along the vertical direction Z from the left end. The positive electrode first collector 51 is an example of the metal second component disclosed herein.

[0057] like Figure 7As shown, the first part 511 is the portion electrically connected to the positive terminal 30 via the riveting part 30c and the welding joint J. The first part 511 is flat. Without particular limitation, the thickness T of the first part 511 is typically 0.5 to 5 mm, for example, about 1 to 3 mm or 1.5 to 2 mm. The first part 511 has an upper surface 51u and a lower surface 51d. A resin member 70 is disposed between the sealing plate 14 and the upper surface 51u of the first part 511. The first part 511 is insulated from the sealing plate 14 by the resin member 70. In the first part 511, a through hole 51h is provided at a position corresponding to the terminal lead-out hole 18 of the sealing plate 14, extending through in the vertical direction Z. Figure 6 As shown, a positive terminal 30 (specifically, shaft 30a) is inserted through the through hole 51h.

[0058] like Figure 7 As shown, a weld joint J, formed by laser welding, is provided at the periphery of the through hole 51h in the first part 511 and at the boundary of the riveting portion 30c of the positive terminal 30. By having the weld joint J, the electrical connection between the positive terminal 30 and the positive current collector 50 can be stably maintained, improving conductivity reliability. The weld joint J is formed in the laser welding process (step S4) described later. The weld joint J is an example of the weld joint between the first component and the second component disclosed herein.

[0059] The weld joint J is provided around the central axis CL of the positive terminal 30. Preferably, the weld joint J is arranged symmetrically with respect to the central axis CL of the positive terminal 30. This ensures that, for example, when using the energy storage device 100, even if vibration or impact is applied, the electrical connection between the positive terminal 30 and the positive current collector 50 can be stably maintained, improving the conductivity reliability of the positive terminal 30. The weld depth of the weld joint J (the maximum length in the vertical direction Z, the vertical length from the lower surface 51d of the first part 511 to the end of the weld joint J on the upper surface 51u side) is typically 0.15 mm or more, for example, about 0.15 to 0.5 mm or 0.3 to 0.4 mm.

[0060] Figure 8 It is shown schematically. Figure 6 A magnified top view of the area near the welded joint J, with Figure 6 Similarly, the inner surface of the casing body 12 side of the sealing plate 14 is indicated. The welded joint J is preferably shaped as an annular (e.g., circular), U-shaped, or C-shaped (semi-circular) along the riveting part 30c when viewed from above, with a particularly preferred shape such as... Figure 8 It is arranged in a ring shape (e.g., annular) as shown. That is, it is particularly preferred that the welded joint J is in the through hole 51h (refer to...). Figure 7The circumference of the welded joint J is continuously arranged around the entire perimeter. The diameter D1 of the annular (e.g., circular) welded joint J is, for example, about 10 mm.

[0061] like Figure 7 , Figure 8 As shown, a roughened portion Ae is provided on the surface and periphery of the weld joint J. Furthermore, the term "periphery" as used here refers to an area where weld spatter may scatter during, for example, the laser welding process (step S4) described later. Therefore, since this varies depending on the laser welding conditions, it is not specifically limited; in one example, it is a range approximately 5 mm from the weld joint J. The roughened portion Ae is the area irradiated with energy rays during the etching process (step S5) described later. Additionally, hereafter, the area surrounding the roughened portion Ae (i.e., the area not irradiated with energy rays during the etching process (step S5)) is sometimes referred to as the general portion An.

[0062] Here, as Figure 7 As shown, in cross-section, the roughened portion Ae is formed axially symmetrically with respect to the central axis CL of the positive terminal 30. Here, as... Figure 8 As shown, when viewed from above, the roughened portion Ae is approximately circular (specifically, a perfect circle) centered on the central axis CL of the positive end 30. The diameter D2 of the roughened portion Ae is preferably larger than the diameter D1 of the weld joint J, more preferably by about 1 to 20 mm, for example, about 10 mm larger. Here, the diameter D2 of the roughened portion Ae is about 20 mm. Furthermore, while the roughened portion Ae is a perfect circle, it can also be other shapes, such as an ellipse or a polygonal shape like a quadrilateral.

[0063] Figure 9 yes Figure 8 A magnified view of the front half of the coarsened portion Ae. (See attached image.) Figure 9 As shown, the roughened portion Ae has a plurality of approximately circular recesses e1. Therefore, the roughness of the roughened portion Ae is greater than that of its surroundings (e.g., the region away from the central axis CL of the positive end 30 from the roughened portion Ae). Figure 8 The general part An) is large. Multiple recesses e1 can be formed by intermittently irradiating energy rays, such as using a pulsed oscillating laser, in the etching process (step S5) described later. In addition, "approximately circular" is a term used to distinguish it from linear (band-like) shapes, including circles and ellipses with an aspect ratio of approximately 1:5 to 5:1, preferably 1:2 to 2:1.

[0064] The multiple recesses e1 are preferably arranged in a regular pattern. In this embodiment, such as... Figure 8 As shown, the roughened portion Ae is roughly circular when viewed from above, as... Figure 9As shown, the plurality of recesses e1 are arranged circumferentially (in an arc shape). The plurality of recesses e1 are evenly arranged with the central axis CL of the positive terminal 30 as the center. However, in other embodiments, the plurality of recesses e1 may also be arranged in a straight line or other arrangements.

[0065] Figure 10 yes Figure 9 A cross-sectional view along line XX. For example... Figure 10 As shown, in the roughened portion Ae, a plurality of recesses e1 are regularly arranged in a cross-section along an arbitrary arc along the circumference. Thus, the cross-section of the roughened portion Ae has an uneven shape, with the unevenness being larger than that of its surroundings (the general portion An). In some embodiments, the diameter w of the recesses e1 (the average diameter of the plurality of recesses e1, the spot diameter) is preferably 5 to 200 μm, more preferably 10 to 150 μm, and even more preferably 20 to 100 μm. Furthermore, the diameter w of the recesses e1 is mainly determined by the specifications of the apparatus used in the etching process (step S5) described later, but can also be adjusted by factors such as the heat or output of energy rays like lasers, irradiation time, etc.

[0066] In some embodiments, the depth h of the recess e1 (the average of the maximum depths of the plurality of recesses e1) is preferably 0.1 μm or more, more preferably 0.5 μm or more, and even more preferably 1 μm or more. Furthermore, the depth h of the recess e1 can be formed primarily by adjusting the output or heat of energy rays such as lasers in the etching process (step S5) described later. Specifically, in the manufacturing method section, by irradiating the recess e1 with energy rays in the etching process so that the depth h of the recess e1 is at or above a predetermined value, the effects of the technology disclosed herein can be highly utilized. Additionally, the depth h of the recess e1 is generally smaller than the welding depth of the weld joint J, preferably 50 μm or less, more preferably 20 μm or less, and even more preferably 10 μm or less. Specifically, in the manufacturing method section, by irradiating the recess e1 with energy rays in the etching process so that the depth h of the recess e1 is at or below a predetermined value, the generation of new weld spatter can be better suppressed. Furthermore, the bonding strength of the weld joint J can be improved.

[0067] like Figure 2 As shown, the second positive current collector 52 extends along the short sidewall 12c of the housing body 12. One end of the second positive current collector 52 ( Figure 2 The upper end) and the positive electrode first collector 51 (specifically the second part 512 (see reference) Figure 6 Electrical connection. The other end of the positive electrode second collector 52 ( Figure 2 The lower end of the positive electrode is attached to the positive electrode tab group 23 and is electrically connected to a plurality of positive electrode tabs 22t. The second positive electrode current collector 52 and the positive electrode tab group 23 are welded together, for example, with a plurality of positive electrode tabs 22t overlapping.

[0068] like Figure 7 As shown, the resin component 70 is an insulating component disposed between the lower surface (inner surface) of the sealing plate 14 and the first portion 511 of the first positive current collector 51. The resin component 70 is made of a resin material that is resistant to and electrically insulating against the non-aqueous electrolyte used and can be elastically deformed, such as fluorinated resins like perfluoroalkoxy fluoropolymer (PFA) or polyphenylene sulfide resin (PPS). Figure 7 , Figure 8 As shown, the resin component 70 has a base portion 70a that extends horizontally along the inner surface of the sealing plate 14. Figure 7 As shown, the base portion 70a is a part that prevents the sealing plate 14 from directly contacting the positive electrode first current collector 51. The base portion 70a has a through hole in the vertical direction Z at a position corresponding to the terminal lead-out hole 18 of the sealing plate 14. The shaft portion 30a of the positive terminal 30 and the cylindrical portion 90a of the gasket 90 are inserted into the through hole.

[0069] like Figure 2 As shown, the negative terminal 40 is electrically connected inside the housing 10 to the negative terminals 24 (specifically, the negative electrode tab group 25) of the electrode bodies 20a, 20b, and 20c via the negative current collector 60. The configuration of the negative terminal 40 can be the same as or different from that of the positive terminal 30 described above. Here, the negative terminal 40 is electrically connected to the first negative current collector 61 of the negative current collector 60, just like the positive terminal 30, through riveting (mechanical fastening) and welding. The negative terminal 40 is inserted through the terminal lead-out hole 19 of the sealing plate 14 and extends from the inside of the sealing plate 14 to the outside. Here, the negative terminal 40 is symmetrically arranged with the positive terminal 30 and has a flange portion (omitted), a shaft portion 40a, and a riveting portion 40c.

[0070] The negative terminal 40 is preferably made of metal, and more preferably of copper or a copper alloy. The negative terminal 40 may also be constructed by joining and integrating two conductive components. For example, the shaft portion 40a or the riveting portion 40c connected to the negative current collector 60 may be made of copper or a copper alloy, while the flange portion protruding from the terminal lead-out hole 19 to the outside of the housing 10 (specifically, the outer surface of the sealing plate 14) may be made of aluminum or an aluminum alloy. The negative terminal 40 is an example of the first metal component disclosed herein.

[0071] like Figure 2As shown, the negative current collector 60 forms a conductive path that electrically connects the negative electrode tab group 25 (negative electrode 24), which consists of multiple negative electrode tabs 24t, and the negative terminal 40. The negative current collector 60 can also be made of the same type of metal as the negative current collector 24c, such as copper, copper alloy, nickel, stainless steel, or other conductive metals. Here, the negative current collector 60 includes a first negative current collector 61 and a second negative current collector 62. The configuration of the first negative current collector 61 and the second negative current collector 62 can be the same as that of the first positive current collector 51 and the second positive current collector 52 of the positive current collector 50. The first negative current collector 61 is an example of a second metal component disclosed herein.

[0072] like Figure 6 As shown, the first negative electrode current collector 61 is welded to the riveting portion 40c of the negative terminal 40. At the boundary between the first negative electrode current collector 61 and the riveting portion 40c, a welded joint J formed by laser welding is provided, similar to the positive electrode side. A roughened portion Ae is provided on the surface and periphery of the welded joint J, similar to the positive electrode side.

[0073] <Method for making sealing plate components>

[0074] like Figure 5 , Figure 6 The sealing plate assembly shown can be manufactured by fixing the positive terminal 30, the positive current collector 50 (specifically, the first positive current collector 51), the negative terminal 40, and the negative current collector 60 (specifically, the first negative current collector 61) to the sealing plate 14 in an insulated state from the sealing plate 14. Without particular limitation, the sealing plate assembly can be manufactured, for example, by a manufacturing method including: an assembly process of components (step S1); a riveting process forming a riveting portion at one end of the shaft portion of the terminal (step S2); a cover placement process placing a cover on the non-welded portion except for the boundary portion between the riveting portion and the current collector (step S3); a laser welding process forming a welded joint at the boundary portion between the riveting portion and the current collector (step S4); and an etching process irradiating the surface and periphery of the welded joint with energy rays (step S5). The laser welding process (step S4) and the etching process (step S5) are examples of the joining methods disclosed herein.

[0075] Furthermore, the riveting process (step S2) and the cover placement process (step S3) are optional and can be omitted in other embodiments. Additionally, the positive electrode side will be described in detail below, but the negative electrode side can be described similarly. In this case, the term "positive electrode" can be appropriately changed to "negative electrode." Furthermore, the manufacturing method disclosed herein can be further included at any stage with additional processes.

[0076] In the assembly process (step S1), the positive terminal 30, the positive current collector 50, the negative terminal 40, and the negative current collector 60 are typically assembled on the sealing plate 14 in a state of insulation from the sealing plate 14. For example, Figure 7 As shown, the flange 30f of the positive terminal 30 is arranged on the outer side of the sealing plate 14 with the gasket 90 in between, and the positive current collector 50 is arranged on the inner side of the sealing plate 14 with the resin member 70 in between. The positive terminal 30 and the positive current collector 50 are then assembled. Specifically, the shaft 30a of the positive terminal 30 before riveting is sequentially inserted into the cylindrical portion 90a of the gasket 90, the terminal lead-out hole 18 of the sealing plate 14, the through hole of the resin member 70, and the through hole 51h of the first part 511 of the positive current collector 50, so that it protrudes downward from the lower surface 51d of the through hole 51h, thereby assembling each component. In addition, the negative terminal 40 and the negative current collector 60 are also assembled to the sealing plate 14 in the same way.

[0077] In the riveting process (step S2), through riveting (rivet connection), one end of the shaft portion 30a of the positive terminal 30 assembled on the sealing plate 14 is deformed, such as... Figure 7 As shown, a riveting portion 30c is formed. Specifically, for example, the lower surface 51d of the first part 511 is placed on a fixed mold, and a compression punch is used to apply a vertical compressive force Z to the shaft portion 30a from above the flange portion 30f of the positive terminal 30. This pushes the end portion of the shaft portion 30a that protrudes downwards from the lower surface 51d of the first part 511 onto the inner surface of the through hole 51h of the positive current collector 50. As a result, the end portion of the shaft portion 30a expands, forming the riveting portion 30c. Through this riveting process, the positive terminal 30 and the positive current collector 50 are fixed to the sealing plate 14, and the terminal lead-out hole 18 is sealed. Similarly, a riveting portion 40c is formed for the negative terminal 40, which can fix the negative terminal 40 and the negative current collector 60 to the sealing plate 14.

[0078] In the cover configuration step (step S3), before the laser welding step (step S4), the cover covers at least a portion of the area except for the part forming the weld joint J. This reduces the area where weld spatter may scatter during the subsequent laser welding step. Consequently, the area to be processed in the subsequent etching step (step S5) is reduced, shortening the etching time. The cover is, for example, made of resin. To prevent scorching during the laser welding step, the cover is preferably positioned approximately 5 mm away from the part forming the weld joint J. In one example, besides… Figure 8 Outside the range of the roughened portion Ae (the range of diameter D2 centered on the central axis CL of the positive terminal 30), for example, a cover can be installed on the entire general portion An in the first collector portion 51 of the positive terminal.

[0079] In the laser welding process (step S4), a laser is irradiated at the boundary between the positive terminal 30 (a first metal component) and the first positive current collector 51 (a second metal component) to form a welded joint. Here, a laser is irradiated at the boundary between the riveting portion 30c, located at the end of the shaft portion 30a of the positive terminal 30, and the periphery of the through hole 51h of the first portion 511 of the positive current collector 50. Thus, a welded joint J is formed at the boundary between the positive terminal 30 and the positive current collector 50. The laser irradiation can be performed using a known laser welding apparatus as before. Preferably, the laser irradiation is performed along the mating line of the riveting portion 30c. The welded joint J is preferably formed around the entire periphery of the through hole 51h (in a ring shape). In addition, the riveting part 40c is also welded around the through hole of the negative electrode current collector 60, so that a welded joint J can be formed at the boundary between the negative electrode 40 and the negative electrode current collector 60.

[0080] The conditions for laser welding are preferably varied on the positive and negative electrode sides depending on the type of metal. There are no particular limitations, but in some embodiments, laser welding is preferably performed according to the conditions shown in Table 1 below. For example, by increasing the laser output to 1000W or more, and further to 2000W or more, or by increasing the laser heat to 100J or more, and further to 200J or more, a weld joint J with the aforementioned welding depth can be appropriately formed. Furthermore, by using a continuously oscillating laser, linear welding can be achieved, which can improve the joint strength.

[0081] Table 1. An example of laser welding conditions.

[0082]

[0083] During laser welding, the high-temperature molten metal generated at the welding site may turn into microparticles (so-called welding spatter). Therefore, after laser welding, welding spatter may sometimes randomly scatter onto the surface and periphery of the weld joint J.

[0084] In the etching process (step S5), energy rays are irradiated onto the surface and periphery of the weld joint J with an output lower than that of the laser in the laser welding process (step S4). This allows the weld sputtering material randomly scattered onto the surface and periphery of the weld joint J to be remelted and removed. The energy rays are preferably lasers or electron beams, more preferably lasers. In this process, a low-output device such as a laser marking machine can be appropriately used, for example. However, the laser welding apparatus used in the laser welding process (step S4) can also be used if the output can be adjusted. The irradiation with energy rays in this process is preferably performed intermittently and regularly using a pulsed oscillating laser. This allows for reliable removal of weld sputtering material with relatively easy device settings. However, in other embodiments, in addition to pulsed oscillating lasers, electron beams or continuously oscillating lasers can be used, with the output varying in a pulse pattern, thereby irradiating in a pulsed manner.

[0085] The energy beam scan is preferably performed along the weld joint J. Since the weld joint J is annular and has a curved portion, the energy beam scan is preferably performed circumferentially (in an arc shape) along the weld joint J. This results in multiple recesses e1 arranged circumferentially. However, the energy beam scan can also be performed in a straight line, a vortex, or other manner.

[0086] In this process, the output of the energy beam (preferably the laser output) is set lower than the laser output in the laser welding process (step S4). This suppresses the generation of new weld spatter in this process. From this perspective, based on the inventors' research, the energy beam output in this process is preferably approximately 200W or less, more preferably 100W or less, further preferably 50W or less, and particularly preferably 30W or less. Furthermore, the energy beam output in this process is preferably approximately 5W or more, more preferably 10W or more. This allows even relatively large weld spatter particles to be easily removed in a short time.

[0087] Furthermore, in some embodiments, when the laser output in the laser welding process (step S4) is set to 100, the energy ray output ratio in this process is preferably 0.1 or more, more preferably 0.2 or more, and for example, even more preferably 0.5 or more. This allows for the efficient removal of weld spatter generated in the laser welding process (step S4) in a shorter time. Additionally, it is easier to appropriately form a recess e1 with a depth h (e.g., 1 to 10 μm) as described above. The aforementioned output ratio is preferably approximately 3 or less, more preferably 2 or less, and in one example, even more preferably 1 or less. This better suppresses the generation of new weld spatter in this process.

[0088] The scanning speed of the energy beam in this process is preferably faster than the scanning speed of the laser in the laser welding process (step S4). This improves productivity or work efficiency. Furthermore, it better suppresses the formation of new weld spatter. Without particular limitation, the scanning speed in this process is preferably 1000 mm / s or more, more preferably 2000 mm / s or more, and even more preferably 3000 mm / s or more. Additionally, the scanning speed in this process is preferably approximately 12000 mm / s or less, more preferably 10000 mm / s or less, and even more preferably 5000 mm / s or less. This makes it easier to remove even relatively large weld spatter.

[0089] When using a pulsed oscillating laser, the pulse frequency of the laser in this process is determined by adjusting the interval between the multiple recesses e1, preferably based on the diameter w of the recesses e1 or the scanning speed, etc. Without particular limitation, the pulse frequency of the laser in this process is preferably 10,000 to 100,000, more preferably 30,000 to 80,000. This allows for easy and reliable removal of randomly scattered welding sputterings.

[0090] Furthermore, the heat generated by the energy beam is expressed as output × irradiation time. Therefore, it is preferable to typically set the heat generated by the energy beam in this process to a value lower than the heat generated by the laser in the laser welding process (step S4). This better suppresses the generation of new weld spatter in this process. From this viewpoint, the heat generated by the energy beam in this process is preferably approximately 0.01 J or less, more preferably 0.001 J or less, and even more preferably 0.0005 J or less. Additionally, the heat generated by the energy beam in this process is preferably approximately 0.00001 J or more, more preferably 0.0001 J or more. This allows even relatively large weld spatter particles to be easily removed in a short time.

[0091] Furthermore, in some embodiments, when the heat of the laser in the laser welding process (step S4) is set to 100, the heat ratio of the energy rays in this process is preferably approximately 0.01 or less, more preferably 0.001 or less, and in one example, even more preferably 0.0005 or less. This allows for the efficient removal of weld spatter generated in the laser welding process (step S4) in a shorter time. Additionally, it is easy to appropriately form a recess e1 with a depth h (e.g., 1–10 μm) as described above.

[0092] Without particular limitation, in some implementations, laser etching can be performed under conditions as shown in Table 2 below.

[0093] Table 2. An example of etching conditions.

[0094]

[0095] In this process, a plurality of generally circular recesses e1 are formed on the surface and periphery of the weld joint J. That is, roughened portions Ae are formed. As described above, with the technology disclosed herein, in the etching process, the surface and periphery of the weld joint are irradiated with energy rays (preferably lasers), thereby efficiently removing weld sputterings that have scattered to random locations during the laser welding process. As a result, the residue of weld sputterings can be reliably reduced. Furthermore, a highly reliable energy storage device 100 can be provided.

[0096] Other methods for removing welding spatter include visually identifying the spatter and manually removing it, or using a camera to detect the location of the spatter and irradiating it with energy rays from a point light source. However, manual removal is costly. Furthermore, there is a possibility of overlooking welding spatter due to human error. On the other hand, methods that irradiate welding spatter with energy rays from a point light source suffer from increased camera costs and longer cycle times due to camera reading and irradiation of energy rays. Compared to these methods, the technology disclosed herein offers a relatively low-cost, efficient, and reliable method for removing welding spatter.

[0097] <Manufacturing Method of Energy Storage Device>

[0098] The energy storage device 100 can be manufactured, for example, by a manufacturing method that prepares the sealing plate assembly, electrode group 20, non-aqueous electrolyte and housing body 12 as described above, including an installation process and a construction process.

[0099] During the installation process, electrode groups 20 are installed on the sealing plate 14 to manufacture... Figure 3 The sealing plate 14 and the electrode group 20 are combined (sealing plate assembly) as shown. Specifically, a second positive current collector 52 is installed on the positive electrode tabs 23 of the electrode bodies 20a, 20b, and 20c, and the second positive current collector 52 is joined (e.g., welded) to the first positive current collector 51 of the sealing plate assembly. Thus, the positive electrode 22 of the electrode bodies 20a, 20b, and 20c is electrically connected to the positive terminal 30. Similarly, a second negative current collector 62 is installed on the negative electrode tabs 25 of the electrode bodies 20a, 20b, and 20c, and the second negative current collector 62 is joined (e.g., welded) to the first negative current collector 61 of the sealing plate assembly. Thus, the negative electrode 24 of the electrode bodies 20a, 20b, and 20c is electrically connected to the negative terminal 40. Therefore, the sealing plate assembly and the electrode group 20 are integrated.

[0100] In the construction process, such as Figure 1 , Figure 2As shown, the electrode assembly 20, integrated with the sealing plate 14, is housed within the internal space of the housing body 12, sealing the housing body 12 and the sealing plate 14. Sealing can be achieved, for example, by welding such as laser welding. Subsequently, a non-aqueous electrolyte is injected through the injection hole 15 of the sealing plate 14, and the injection hole 15 is sealed by the sealing member 16, thereby sealing the energy storage device 100. The energy storage device 100 can be manufactured using this method.

[0101] <Applications of Energy Storage Devices>

[0102] The energy storage device 100 can also be appropriately used as a battery pack formed by electrically connecting multiple energy storage devices 100 together via a busbar. In this case, the multiple energy storage devices 100 can be electrically connected, for example, by providing a busbar or other conductive component between the positive terminal 30 and the negative terminal 40 of adjacent energy storage devices 100. The energy storage device 100 can be used for various purposes, such as being appropriately used as a power source (drive power source) for motors mounted in vehicles such as passenger cars and trucks. 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).

[0103] The present invention has been described above with reference to some embodiments, but these embodiments are merely examples. The present invention can also be implemented in various other forms. The present invention can be implemented based on the content disclosed in this specification and common technical knowledge in the field. The technology described in the claims includes configurations obtained by various modifications and alterations to the embodiments illustrated above. For example, a portion of the above embodiments can be replaced with other modifications, and other modifications can be added to the above embodiments. Furthermore, features of the technology that are not described as essential components can be appropriately omitted.

[0104] <Example 1>

[0105] For example, in the above embodiment, in the cover configuration step (step S3), the cover is configured except for the area of ​​diameter D2 centered on the central axis CL of the positive terminal 30, and in the etching step (step S5), a roughened portion Ae that is approximately circular when viewed from above is formed (see reference). Figure 8 However, it is not limited to this. For example, such as Figure 7It is known that the bottom surface of the positive terminal 30 (the inner circumferential side of the annular riveting portion 30c) is recessed. Therefore, it is sometimes difficult to irradiate with energy rays during the etching process. In such cases, it is preferable to place a cover on the recessed portion of the positive terminal 30 during the cover placement process (step S3).

[0106] If a cover is placed on the recessed portion of the positive terminal 30 during the cover placement process (step S3), no welding sputtering will scatter onto this portion during the laser welding process (step S4). Therefore, during the etching process (step S5), it is not necessary to irradiate this portion with energy rays, which can shorten the time required for the etching process. Figure 11 This is the variation involved in the case of... Figure 8 A comparable diagram. (For example...) Figure 11 As shown, in this modified example, during the etching process, a roughened portion Ae1, which appears as a ring (donut-shaped) when viewed from above, is formed on the surface and periphery of the weld joint J.

[0107] As an example, in Figure 12 Examples of the negative electrode side involved in this modification are shown in (A) to (D). In addition, in this embodiment, the negative terminal 40, which is the first component, and the first negative current collector 61, which is the second component, are both made of copper (C1020). Figure 12 Image (A) is an observation image of the weld joint J before the etching process (step S5). Figure 12 (B) is Figure 12 A magnified view of (A). For example... Figure 12 As shown in (A), there are two welded joints J, each arranged in a roughly C-shape. Figure 12 As shown by the circular markings in (B), it can be seen that welding spatter has scattered to random locations near the weld joint J.

[0108] Therefore, in this embodiment, the etching process is performed using the apparatus described below. Furthermore, the etching conditions using a laser are as shown in Table 2 above.

[0109] • Device: 3-Axis hybrid laser engraving machine (model: MD-X2500A) manufactured by Keyence Corporation

[0110] • Laser wavelength: 1064nm (IR) • Laser power: 90%

[0111] • Type of full-coat line: contour line • Spacing of full-coat lines: 0.06mm

[0112] Figure 12 Image (C) is an observation image of the weld joint J after the etching process (step S5). Figure 12 (D) is Figure 12 A magnified view of (C). For example... Figure 12 As shown in (C), multiple roughly circular recesses are formed on the surface and periphery of the welded joint J, which can be considered as forming annular roughened portions Ae1. Furthermore, as... Figure 12 As shown in (D), the solder sputtering present before the etching process is removed after the etching process.

[0113] <Second Variation>

[0114] For example, in the above embodiment, the first component is a terminal (positive terminal 30 or negative terminal 40), and the second component is a current collector (positive first current collector 51 or negative first current collector 61). However, it is not limited to this. For example, in the battery pack described above, the first component may be a terminal (positive terminal 30 or negative terminal 40), and the second component may be a busbar or other conductive component.

[0115] As described above, the following components can be listed as specific forms of the technology disclosed herein.

[0116] Item 1: A joining method, wherein the joining method comprises: a laser welding process, wherein the laser welding process irradiates a boundary portion of a first metal component and a second metal component with a laser to form a welded joint; and an etching process, wherein the etching process irradiates an energy beam on the surface and periphery of the welded joint with a lower output than that of the laser welding process, thereby forming a plurality of generally circular recesses on the surface and periphery of the welded joint.

[0117] Item 2: The bonding method as described in Item 1, wherein, in the above-mentioned etching process, the output of the energy ray is set to 50W or less.

[0118] Item 3: The joining method as described in Item 1 or 2, wherein, in the etching process, the scanning speed of the energy rays is faster than that of the laser welding process.

[0119] Item 4: The bonding method as described in any one of Items 1 to 3, wherein, in the etching process described above, a plurality of the above-mentioned recesses with a diameter of 20 to 100 μm and a depth of 1 to 10 μm are formed.

[0120] Item 5: The joining method as described in any one of Items 1 to 4, wherein, in the etching process described above, a plurality of the recesses described above are formed regularly.

[0121] Item 6: The joining method as described in any one of Items 1 to 5, wherein, in the etching process described above, the energy rays are scanned along the weld joint.

[0122] Item 7: The joining method as described in any one of Items 1 to 6, wherein, in the etching process described above, the energy rays are scanned circumferentially along the welded joint having a curved portion to form a plurality of the recesses arranged circumferentially.

[0123] Item 8: The joining method as described in any one of Items 1 to 7, wherein a cover configuration step is further included before the laser welding step, the cover configuration step using a cover to cover at least a portion of the area other than the portion forming the welded joint, and in the etching step, the area not covered by the cover is irradiated with the energy rays.

[0124] Item 9: A method for manufacturing an energy storage device, the energy storage device comprising a first component and a second component as constituent elements, wherein the method for manufacturing the energy storage device comprises any one of items 1 to 8.

[0125] Item 10: An energy storage device, wherein the energy storage device comprises: a first metal component; a second metal component; a welded joint between the first component and the second component; and a roughened portion provided on the surface and periphery of the welded joint, the roughened portion having a plurality of generally circular recesses, the recesses being larger than the surrounding area.

[0126] Item 11: The energy storage device as described in Item 10, wherein the diameter of the recess is 20 to 100 μm and the depth is 1 to 10 μm.

[0127] Item 12: The energy storage device as described in Item 10 or 11, wherein a plurality of the aforementioned recesses are arranged in a regular manner.

[0128] Item 13: The energy storage device as described in any one of Items 10 to 12, wherein the roughened portion is configured to be approximately circular or annular in plan view, and the plurality of the recesses are arranged circumferentially.

[0129] Item 14: The energy storage device as described in any one of Items 10 to 13, wherein the energy storage device comprises: an electrode body including a first electrode and a second electrode; a housing housing the electrode body; a terminal electrically connected to the first electrode and mounted on the housing; and a current collector disposed within the housing to electrically connect the first electrode to the terminal, wherein the first component is the terminal and the second component is the current collector.

[0130] Explanation of reference numerals in the attached figures

[0131] 10 housing

[0132] Electrode bodies 20a, 20b, and 20c

[0133] 22 Positive electrode (Electrode 1)

[0134] 24 Negative electrode (second electrode)

[0135] 30 Positive Terminal

[0136] 30c riveting part

[0137] 40 negative terminal (terminal)

[0138] 50 Positive Current Collector

[0139] 51 Positive electrode first current collector (current collector)

[0140] 60 negative electrode current collector

[0141] 61 Negative electrode first collector section (collector section)

[0142] 100 energy storage device

[0143] J-welded joint

[0144] Ae roughened section

[0145] e1 concavity

[0146] An General Section

Claims

1. A joining method, wherein, The joining method includes: A laser welding process, wherein a laser is irradiated onto the boundary portion of a first metal component and a second metal component to form a welded joint; and The etching process, which uses energy rays to irradiate the surface and periphery of the welded joint with a lower output than the laser welding process described above, forms a plurality of generally circular recesses on the surface and periphery of the welded joint.

2. The joining method as described in claim 1, wherein, In the above etching process, the output of the energy rays is set to 50W or less.

3. The joining method as described in claim 1, wherein, In the etching process described above, the scanning speed of the energy rays is faster than that of the laser welding process described above.

4. The joining method as described in claim 1, wherein, In the above etching process, a plurality of the above-mentioned recesses with a diameter of 20 to 100 μm and a depth of 1 to 10 μm are formed.

5. The joining method as described in claim 1, wherein, In the above etching process, multiple recesses are formed in a regular manner.

6. The joining method as claimed in claim 1, wherein, In the above etching process, the energy rays are scanned along the above weld joint.

7. The joining method as claimed in claim 1, wherein, In the above etching process, the energy rays are scanned circumferentially along the weld joint having a curved portion to form a plurality of the above recesses arranged circumferentially.

8. The joining method as claimed in claim 1, wherein, Prior to the laser welding process described above, a cover configuration process is included, which uses a cover to cover at least a portion of the area other than the area forming the welded joint. In the above etching process, the area not covered by the above cover is irradiated with the above energy rays.

9. A method for manufacturing an energy storage device, the energy storage device comprising a first component and a second component as constituent elements, wherein, The manufacturing method of the above-mentioned energy storage device includes the joining method according to any one of claims 1 to 8.

10. An energy storage device, wherein, The aforementioned energy storage device comprises: a first metal component; a second metal component; a welded joint between the first and second components; and a roughened portion provided on the surface and periphery of the welded joint. The roughened portion has multiple roughly circular recesses, with the concave and convex parts being larger than their surroundings.

11. The energy storage device as claimed in claim 10, wherein, The diameter of the aforementioned recess is 20–100 μm, and the depth is 1–10 μm.

12. The energy storage device as claimed in claim 10, wherein, The aforementioned recesses are arranged in a regular pattern.

13. The energy storage device as claimed in claim 10, wherein, The aforementioned roughened portion is designed to appear roughly circular or annular when viewed from above. Multiple of the aforementioned recesses are arranged circumferentially.

14. The energy storage device according to any one of claims 10 to 13, wherein, The above-mentioned energy storage device has the following features: An electrode body, comprising a first electrode and a second electrode; A housing that contains the aforementioned electrode body; Terminal, which is electrically connected to the first electrode, is mounted on the housing; and A current collector, disposed within the aforementioned housing, electrically connects the first electrode to the aforementioned terminal. The first component mentioned above is the terminal mentioned above. The second component mentioned above is the current collector.

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