Terminal member, secondary battery provided with the terminal member, and battery pack

Abstract

The present disclosure relates to a terminal member, a secondary battery provided with the terminal member, and a battery pack. According to the present disclosure, a terminal member capable of reducing thermal degradation caused by irradiation of a light beam to a metal joint is provided. The terminal member disclosed herein is provided with a first member made of metal and a second member made of metal in a plate shape, and a metal joint that is joined by metal joining is formed at a boundary surface where the first member and the second member overlap. At a surface of the second member on the side opposite to the above-described boundary surface, a protrusion that protrudes from the surface is formed around the metal joint.

Description

Technical Field

[0001] This disclosure relates to terminal components, secondary batteries having the terminal components, and battery packs. Background Technology

[0002] Lithium-ion batteries and other rechargeable batteries are preferred for use as high-output power supplies for driving electric vehicles, hybrid vehicles, and other similar vehicles due to their lightweight nature and high energy density; demand for these batteries is expected to increase in the future. In high-output power supplies for driving, battery packs consisting of multiple rechargeable batteries (single cells) electrically connected to each other are preferred for increasing output. In a battery pack, typically, adjacent single cells are connected by a busbar, linking one electrode terminal to another.

[0003] Patent Document 1 discloses a structure for a connecting busbar for a battery pack. This connecting busbar has a protrusion that extends toward the electrode terminals. By welding the electrode terminals to the connecting busbar at this protrusion, gaps between the connecting busbar and the electrode terminals caused by deviations in the height of the electrode terminals and errors in the shape of the connecting busbar can be suppressed.

[0004] Furthermore, Patent Document 2 discloses a structure for the welding portion between the busbar and the external terminals in a battery pack. The busbar used in Patent Document 2 is a plate-shaped component, having two terminal connection portions that overlap with the external terminals, and a connecting portion that connects the two terminal connection portions. A linear welding portion is formed at the location where the terminal connection portions overlap with the external terminals. This welding portion is non-circular, having a straight portion extending in a direction orthogonal to the arrangement direction of the plurality of individual cells constituting the battery pack, and two arc-shaped portions extending from both ends of the straight portion and curving toward a side opposite to the side where the connecting portion is located. This suppresses damage to the welding portion between the busbar and the external terminals.

[0005] Patent Document 1: Japanese Patent Application Publication No. 2015-99759

[0006] Patent Document 2: Japanese Patent Application Publication No. 2018-181552

[0007] However, when welding busbars to electrode terminals, beam welding, such as laser welding, is widely used. In beam welding, welding to the electrode terminals is achieved by locally melting the busbar in the irradiated area of ​​the beam and then solidifying the molten part. However, if the beam is directed at metal joints present near the welding area, thermal degradation of the metal joints may occur, potentially leading to a decrease in joint strength and conductivity. Summary of the Invention

[0008] Therefore, this disclosure was made in view of the above-mentioned situation, and its main object is to provide a terminal component that can reduce thermal degradation caused by light beam irradiation onto the metal joint.

[0009] To achieve the above objectives, the terminal component disclosed herein comprises a first metal component and a second metal component in the shape of a plate. A metal joint is formed at the boundary surface where the first component and the second component overlap, and the metal component is joined by a metal connection. On the surface of the second component opposite to the boundary surface, a raised portion is formed around the metal joint.

[0010] According to this structure, a raised portion protruding from the surface of the second component is formed around the metal joint. Furthermore, the raised portion functions as a wall to block light beams from irradiating the vicinity of the metal joint. This suppresses heat input caused by light beam irradiation towards the metal joint, thereby reducing thermal degradation of the metal joint.

[0011] In a preferred embodiment of the terminal component disclosed herein, the surface of the second component opposite to the boundary surface has a recess, within which the raised portion is formed. Furthermore, it is preferable that the maximum height of the raised portion from the bottom of the recess does not exceed the height from the bottom of the recess to the surface having the recess. In this structure, since the raised portion is formed without extending beyond the interior of the recess, it is possible to properly overlap the surface of the second component with the recess for welding. Moreover, the raised portion within the recess reduces heat input caused by light beam irradiation towards the metal joint.

[0012] Furthermore, in a preferred embodiment of the terminal component disclosed herein, the aforementioned raised portion is continuously formed to surround the aforementioned metal joint. In this structure, the raised portion is formed around the entire periphery of the metal joint, thus enabling more appropriate suppression of heat input caused by light beams irradiating the metal joint from various directions.

[0013] Furthermore, in a preferred embodiment of the terminal component disclosed herein, the aforementioned raised portion has a flat upper surface. This allows for a more appropriate reduction in heat input caused by light beam irradiation onto the metal joint.

[0014] Alternatively, the terminal component disclosed herein may also be configured as an ultrasonic joint where the aforementioned metal joint is joined by ultrasonic bonding.

[0015] Furthermore, according to this disclosure, a secondary battery incorporating the terminal components disclosed herein is provided. The disclosed secondary battery includes: an electrode body comprising a positive electrode and a negative electrode; a battery case housing the electrode body therein; a positive terminal electrically connected to the positive electrode; and a negative terminal electrically connected to the negative electrode. Moreover, at least one of the positive and negative terminals includes the terminal components disclosed herein. Therefore, when an external component is beam-welded to the terminal components of the secondary battery, heat input caused by beam irradiation to the metal joint of the terminal components is reduced, thereby reducing thermal degradation of the metal joint.

[0016] Furthermore, according to this disclosure, a battery pack incorporating the secondary battery disclosed herein is provided. The battery pack disclosed herein is a battery pack formed by electrically connecting and arranging multiple individual cells, characterized in that the secondary battery disclosed herein is at least one of the multiple individual cells. In a preferred embodiment, the multiple individual cells are electrically connected by a busbar to the positive terminal of one individual cell and the negative terminal of another individual cell, respectively. Here, the terminal component has a weld portion for welding the second component and the busbar beam electrically connected to the second component, and the raised portion is located between the metal joint and the weld portion. This enables a battery pack that reduces thermal degradation of the metal joint. Attached Figure Description

[0017] Figure 1 This is a partial cross-sectional view schematically illustrating the structure of a lithium-ion battery according to one embodiment.

[0018] Figure 2 It means Figure 1 Sectional view of section II-II.

[0019] Figure 3 It means Figure 2 Sectional view of section III-III.

[0020] Figure 4 It is a perspective view schematically showing the structure of a battery pack according to one embodiment.

[0021] Figure 5 This is a cross-sectional view schematically illustrating the structure of a terminal component according to one embodiment.

[0022] Figure 6 This is a top view schematically illustrating the structure of a terminal component according to one embodiment.

[0023] Figure 7 This is a schematic diagram illustrating the structure of a battery pack according to one embodiment when the terminal component disclosed herein is used as the external terminal of the negative terminal of a single cell.

[0024] Figure 8 It is a three-dimensional diagram that schematically represents the structure of the mold head.

[0025] Figure 9 It is a top view that schematically represents the structure of the mold head.

[0026] Figure 10 It is a side view schematically representing the structure of the mold head.

[0027] Figure 11A This is a schematic diagram showing the structure of the terminal components before ultrasonic bonding.

[0028] Figure 11B This is a schematic diagram illustrating the process of ultrasonic bonding.

[0029] Explanation of reference numerals in the attached figures

[0030] 10…Lithium-ion secondary battery; 20…Electrode body; 21…Positive electrode sheet; 21a…Positive current collector foil; 21a1…Unformed portion; 21b…Positive active material layer; 22…Negative electrode sheet; 22a…Negative current collector foil; 22a1…Unformed portion; 22b…Negative active material layer; 31, 32…Separator sheet; 41…Battery case; 41a…Case body; 41a1…Opening; 41b…Cover; 41b1…Mounting hole; 42…Positive terminal; 42a…Internal terminal of positive electrode; 42b…External terminal of positive electrode; 43 …negative terminal; 43a…internal terminal of negative electrode; 43a1…base; 43a2…connecting piece; 43b…external terminal of negative electrode; 43b1…head; 43b2…shaft; 43b3…rivet piece; 61…bottom surface; 62, 63…wide surface; 64, 65…narrow surface; 71…washer; 71a…seat; 71b…protrusion; 71c…sidewall; 72…insulator; 72a…bottom wall; 72b…hole; 90…battery pack; 91…separator; 92A, 92B…end plate; 93… Busbar; 94… Restraint band; 96… Screw; 98… End spacer; 99… Welded part; 100… Die head; 110… Base part; 112… Exposed surface; 130… Platform part; 131… Upper surface; 132… Peripheral wall; 132a… Wide surface; 132b… Narrow surface; 150… Crimping part; 152… Protrusion; 152a… Upper surface; 152b… Bottom surface; 152c… Side surface; 154… Zigzag part; 170… Burr accumulation part; 200… Terminal component; 210… First component; 212… Shaft portion; 212a…end end; 214…flange portion; 216…cylindrical portion; 220…second component; 221…surface; 222…recess; 222a…bottom; 222b…side peripheral surface; 223…surface; 224…recess; 224a…bottom; 224b…side peripheral surface; 225…protrusion; 226…contact portion; 230…metal joint; 300…anvil; T1…height of protrusion; T2…depth of recess; T3…height of platform; T4…height of protrusion; W1…width of exposed surface. Detailed Implementation

[0031] The technology disclosed herein will now be described in detail. Matters requiring implementation other than those specifically mentioned in this specification can be grasped by those skilled in the art based on prior art in this field. The technology disclosed herein can be implemented based on the content disclosed in this specification and common technical knowledge in this field.

[0032] Furthermore, the figures are depicted schematically, and the dimensional relationships (length, width, thickness, etc.) do not reflect actual dimensional relationships. Additionally, in the figures described below, sometimes the same reference numerals are used to denote parts or components that serve the same function, and repeated descriptions are omitted or simplified.

[0033] In this specification, when the numerical range is recorded as A~B (where A and B are arbitrary values), it means, as in general interpretation, that it is above A and below B (including the range that exceeds A but is below B).

[0034] In this specification, "secondary battery" generally refers to an energy storage device that generates a charging and discharging reaction by the movement of charge carriers between a pair of electrodes (positive and negative electrodes) via an electrolyte. Besides so-called rechargeable batteries such as lithium-ion batteries, nickel-metal hydride batteries, and nickel-cadmium batteries, secondary batteries also include capacitors such as electric double-layer capacitors. The following explanation will use a lithium-ion secondary battery as an example.

[0035] Lithium-ion secondary batteries 10

[0036] Figure 1 This is a partial cross-sectional view schematically showing the structure of a lithium-ion secondary battery 10. Figure 1 The image depicts a state where the interior of the battery box 41, which is roughly rectangular, is exposed along one side of a wide surface. Figure 1 The lithium-ion secondary battery 10 shown is a so-called closed-type battery. Figure 2 It means Figure 1 A sectional view of section II-II. Figure 2 The image shows a partial cross-sectional view schematically depicting the state in which the interior of the battery box 41, which is roughly rectangular, is exposed along a narrow section on one side.

[0037] like Figure 1 As shown, the lithium-ion secondary battery 10 includes an electrode body 20, a battery box 41, a positive terminal 42, and a negative terminal 43.

[0038] <Electrode 20>

[0039] The electrode body 20 is housed in the battery case 41 while covered by an insulating film (not shown). The electrode body 20 includes a positive electrode plate 21 as a positive electrode element, a negative electrode plate 22 as a negative electrode element, and separator plates 31 and 32 as separators. The positive electrode plate 21, the first separator plate 31, the negative electrode plate 22, and the second separator plate 32 are all long strip-shaped components.

[0040] For the positive electrode 21, a positive electrode current collector foil 21a (e.g., aluminum foil) with a predetermined width and thickness has a positive electrode active material layer 21b formed on both sides, except for the unformed portion 21a1 at one end in the width direction, which is set with a constant width. The positive electrode active material is, for example, a material in a lithium-ion secondary battery, such as a lithium transition metal composite material, that can release lithium ions during charging and absorb lithium ions during discharging. Generally, various positive electrode active materials other than lithium transition metal composite materials have been proposed, and there is no particular limitation.

[0041] For the negative electrode 22, a negative electrode current collector foil 22a (here, a copper foil) with a predetermined width and thickness has a negative electrode active material layer 22b formed on both sides, except for the unformed portion 22a1 on one side of the width direction which is set with a constant width. The negative electrode active material is, for example, a material like natural graphite used in lithium-ion secondary batteries that can absorb lithium ions during charging and release the lithium ions absorbed during charging during discharging. Generally, various negative electrode active materials other than natural graphite have been proposed, and there is no particular limitation.

[0042] For example, in the separators 31 and 32, porous resin sheets that allow electrolyte to pass through are used to achieve the required heat resistance. Various techniques have been proposed for separators 31 and 32, and there are no particular limitations.

[0043] Here, the width of the negative electrode active material layer 22b is, for example, wider than that of the positive electrode active material layer 21b. The widths of the separators 31 and 32 are wider than that of the negative electrode active material layer 22b. The unformed portions 21a1 of the positive electrode current collector foil 21a and 22a1 of the negative electrode current collector foil 22a face opposite directions in the width direction. Furthermore, the positive electrode sheet 21, the first separator 31, the negative electrode sheet 22, and the second separator 32 are aligned in the length direction, stacked sequentially, and wound. The negative electrode active material layer 22b covers the positive electrode active material layer 21b while the separators 31 and 32 are sandwiched between them. The negative electrode active material layer 22b is covered by the separators 31 and 32. The unformed portions 21a1 of the positive electrode current collector foil 21a are exposed on one side in the width direction of the separators 31 and 32. The unformed portion 22a1 of the negative electrode current collector foil 22a is exposed from the separators 31 and 32 on the opposite side in the width direction.

[0044] like Figure 1 As shown, the electrode body 20 is flat along a plane including the winding axis so that it can be accommodated in the main body 41a of the battery case 41. Moreover, at the end of the winding axis of the electrode body 20, an unformed portion 21a1 of the positive electrode current collector foil 21a is arranged on one side, and an unformed portion 22a1 of the negative electrode current collector foil 22a is arranged on the opposite side.

[0045] <Battery Box 41>

[0046] like Figure 1 As shown, the battery case 41 houses the electrode body 20. The battery case 41 has: a case body 41a, which is a generally rectangular shape with an opening on one side; and a cover 41b, which is fitted to the opening. In this embodiment, from the viewpoint of lightweighting and ensuring the required rigidity, the case body 41a and the cover 41b are respectively formed of aluminum or an aluminum alloy mainly composed of aluminum.

[0047] <Box body 41a>

[0048] like Figure 1 and 2 As shown, the box body 41a has a generally rectangular, cuboid shape with an opening on one side. The box body 41a has a generally rectangular base 61, a pair of wide faces 62 and 63, and a pair of narrow faces 64 and 65. The pair of wide faces 62 and 63 rise from the long sides of the base 61. The pair of narrow faces 64 and 65 rise from the short sides of the base 61. An opening 41a1, surrounded by the pair of wide faces 62 and 63 and the pair of narrow faces 64 and 65, is formed on one side of the box body 41a.

[0049] Cover 41b

[0050] The lid 41b is fitted into the opening 41a1 of the box body 41a, which is surrounded by the long sides of a pair of wide facets 62, 63 and the short sides of a pair of narrow facets 64, 65. Furthermore, the periphery of the lid 41b engages with the edge of the opening 41a1 of the box body 41a. This engagement can be achieved, for example, through seamless, continuous welding. This welding can be achieved, for example, through laser welding.

[0051] In this embodiment, a positive terminal 42 and a negative terminal 43 are mounted on the cover 41b. The positive terminal 42 has an internal terminal 42a and an external terminal 42b. The negative terminal 43 has an internal terminal 43a and an external terminal 43b. The internal terminals 42a and 43a are respectively mounted on the inner side of the cover 41b via an insulator 72. The external terminals 42b and 43b are respectively mounted on the outer side of the cover 41b via a washer 71. The internal terminals 42a and 43a extend inside the housing body 41a. The internal terminal 42a of the positive terminal is connected to the unformed portion 21a1 of the positive current collector foil 21a. The internal terminal 43a of the negative terminal is connected to the unformed portion 22a1 of the negative current collector foil 22a.

[0052] like Figure 1 As shown, the unformed portions 21a1 of the positive current collector foil 21a and the unformed portions 22a1 of the negative current collector foil 22a of the electrode body 20 are mounted on the internal terminals 42a and 43a respectively mounted on both sides of the cover 41b along its long side. The electrode body 20 is housed in the battery case 41 with the internal terminals 42a and 43a mounted on the cover 41b. Furthermore, a wound type electrode body 20 is illustrated here. The construction of the electrode body 20 is not limited to this method. For example, the electrode body 20 can also be constructed by alternately stacking positive and negative electrode sheets with separators between them. Additionally, multiple electrode bodies 20 may be housed within the battery case 41.

[0053] Figure 3 It means Figure 2 A sectional view of section III-III. Figure 3 The image shows a cross-section of the portion where the negative terminal 43 is mounted to the cover 41b. In this embodiment, the external terminal 43b of the negative electrode uses a component that joins different types of metals. Figure 3 The cross-sectional shape of the external terminal 43b is schematically shown in the diagram. Furthermore, in... Figure 3 The structure of the different types of metals constituting the external terminal 43b, as well as the interfaces between the different types of metals, are omitted.

[0054] like Figure 3 As shown, the cover 41b has a mounting hole 41b1 for mounting the external terminal 43b of the negative electrode. The mounting hole 41b1 penetrates the cover 41b at a predetermined position. The internal terminal 43a and the external terminal 43b of the negative electrode are mounted in the mounting hole 41b1 of the cover 41b in such a way that the washer 71 and the insulator 72 are positioned between them.

[0055] Here, as Figure 3 As shown, the external terminal 43b of the negative electrode includes a head 43b1, a shaft portion 43b2, and a rivet tab 43b3. The head 43b1 is located on the outside of the cover 41b. The head 43b1 is a generally flat plate-shaped portion larger than the mounting hole 41b1. The shaft portion 43b2 is fitted into the mounting hole 41b1 via a washer 71. The shaft portion 43b2 protrudes downward from approximately the center of the head 43b1. Figure 3 As shown, the rivet 43b3 is located inside the cover 41b and is riveted to the internal terminal 43a of the negative electrode. The rivet 43b3 extends from the shaft portion 43b2 and is bent after being inserted into the cover 41b to rivet to the internal terminal 43a of the negative electrode.

[0056] <Washer 71>

[0057] like Figure 3 As shown, washer 71 is a component that is mounted on the mounting hole 41b1 of cover 41b and the outer surface of cover 41b. In this embodiment, washer 71 includes a seat portion 71a, a protrusion 71b, and a sidewall 71c. The seat portion 71a is the portion that is fitted onto the outer surface of cover 41b. The protrusion 71b has an external shape that extends along the inner side of the mounting hole 41b1 so as to be fitted onto the mounting hole 41b1 of cover 41b. The inner side of the protrusion 71b forms a mounting hole for mounting the shaft portion 43b2 of the external terminal 43b. The sidewall 71c rises upward from the periphery of the seat portion 71a. The head 43b1 of the external terminal 43b is fitted into the portion surrounded by the sidewall 71c of washer 71.

[0058] Gasket 71 is disposed between cover 41b and external terminal 43b to ensure insulation between them. Additionally, gasket 71 ensures the airtightness of mounting hole 41b1 in cover 41b. From this perspective, materials with excellent chemical resistance and durability can be used. In this embodiment, PFA is used for gasket 71. PFA is a copolymer of tetrafluoroethylene and perfluoroalkylvinylether. However, the material used for gasket 71 is not limited to PFA.

[0059] <Insulator 72>

[0060] The insulator 72 is a component fitted around the mounting hole 41b1 of the cover 41b, inside the cover 41b. The insulator 72 includes a bottom wall 72a and a hole 72b. The bottom wall 72a is a portion disposed along the inner surface of the cover 41b. In this embodiment, the bottom wall 72a is a generally flat portion. The bottom wall 72a is disposed along the inner surface of the cover 41b. The hole 72b is a hole corresponding to the inner surface of the protrusion 71b of the gasket 71. Because it is disposed inside the battery case 41, the insulator 72 can also possess the required chemical resistance. In this embodiment, PPS is used for the insulator 72. PPS is polyphenylene sulfide resin. However, the material used for the insulator 72 is not limited to PPS.

[0061] The internal terminal 43a of the negative electrode has a base 43a1 and a connecting piece 43a2 (see reference). Figure 1 and 2 The base 43a1 is the portion fitted onto the bottom wall 72a of the insulator 72. The connecting piece 43a2 extends from one end of the base 43a1, extends within the housing body 41a, and connects to the unformed portion 22a1 of the negative electrode current collector foil 22a (see reference). Figure 1 and 2 ).

[0062] In this embodiment, a protrusion 71b is fitted into the mounting hole 41b1, and a washer 71 is fitted onto the outside of the cover 41b. An external terminal 43b is fitted onto the washer 71. At this time, the shaft portion 43b2 of the external terminal 43b is inserted through the protrusion 71b of the washer 71, and the head 43b1 of the external terminal 43b is positioned on the seat portion 71a of the washer 71. An insulator 72 and a negative terminal 43 are fitted onto the inside of the cover 41b. Furthermore, as... Figure 3 As shown, the rivet tab 43b3 of the external terminal 43b is bent to rivet it to the base 43a1 of the negative terminal 43. To improve conductivity, the rivet tab 43b3 of the external terminal 43b can be partially metal-jointed to the base 43a1 of the negative terminal 43.

[0063] However, the required level of oxidation-reduction resistance for the internal terminal 42a of the positive electrode in the lithium-ion secondary battery 10 is no higher than that for the negative electrode. Furthermore, from the viewpoint of requiring both oxidation-reduction resistance and lightweight design, aluminum can be used for the internal terminal 42a of the positive electrode. Conversely, the required level of oxidation-reduction resistance for the internal terminal 43a of the negative electrode is higher than that for the positive electrode. From this viewpoint, copper can be used for the internal terminal 43a of the negative electrode. On the other hand, for the busbar connected to the external terminal 43b, from the viewpoint of lightweight design and low cost, aluminum or an aluminum alloy is used.

[0064] Figure 4 This is a schematic perspective view of a battery pack 90. ​​The battery pack 90 includes a lithium-ion secondary battery 10 as a single cell. Multiple lithium-ion secondary batteries 10 are electrically connected and arranged in the battery pack 90, with spacers 91 between the lithium-ion secondary batteries 10. Additionally, the battery pack 90 includes a constraint mechanism. For example, as shown, the battery pack 90 includes a pair of end plates 92A and 92B, a constraint band 94, and multiple screws 96. The pair of end plates 92A and 92B are arranged at both ends of the battery pack 90 in the arrangement direction of the lithium-ion secondary batteries 10. The constraint band 94 is mounted on the pair of end plates 92A and 92B and is installed on the pair of end plates 92A and 92B by screws 96. The spacers 91 are sandwiched between two adjacent lithium-ion secondary batteries 10. Furthermore, end spacers 98 are respectively arranged between the lithium-ion secondary battery 10 and the end plate 92A, and between the lithium-ion secondary battery 10 and the end plate 92B. The positive terminal 42 of one lithium-ion secondary battery 10 constituting the battery pack 90 is electrically connected to the negative terminal 43 of another lithium-ion secondary battery 10 via a busbar 93. The busbar 93 is welded to the positive terminal 42 and the negative terminal 43 by beam welding. Thus, the lithium-ion secondary batteries 10 constituting the battery pack 90 are electrically connected in series sequentially. However, the shape, size, number, arrangement, and connection method of the lithium-ion secondary batteries 10 constituting the battery pack 90 are not limited to the form disclosed herein and can be appropriately modified.

[0065] The inventors have investigated a terminal component in which multiple metal parts are joined by a metal bonding process in at least one of the positive terminal 42 and the negative terminal 43. By constructing the terminal component from multiple metal parts, it is possible to construct a terminal component made of different types of metal. With such a terminal component, the portion connected to the busbar 93 of the terminal component can be of the same type of metal as the busbar 93, and the portion connected to the internal terminal of the terminal component can be of the same type of metal as the internal terminal. This results in a good electrical connection between the terminal component and the busbar 93 and the internal terminal, and further improves the bonding strength. However, if a beam of light generated by beam welding (e.g., laser welding) is irradiated onto the metal bonding portion of the terminal component and its vicinity, thermal degradation of the metal bonding portion occurs due to the heat input generated by the beam irradiation, potentially reducing the bonding strength and conductivity. Therefore, the terminal component 200 disclosed herein is characterized by having a raised portion 225 around the metal bonding portion capable of blocking beam irradiation. The terminal component 200 will be described below.

[0066] Figure 5 This is a cross-sectional view schematically showing the structure of the terminal component 200. Figure 6 This is a top view schematically illustrating the structure of the terminal component 200. The terminal component 200 includes a first component 210 and a second component 220 superimposed on the first component 210. The first component 210 and the second component 220 are each made of metal. In this embodiment, the first component 210 is made of copper, and the second component 220 is made of aluminum.

[0067] like Figure 5 As shown, in this embodiment, the first component 210 has a shaft portion 212 and a flange portion 214 extending outwardly from one end of the shaft portion 212. The end portion 212a of the first component 210 on the side where the flange portion 214 is provided is rounded. The flange portion 214 is continuously formed in the circumferential direction of the shaft portion 212. The outer edge of the flange portion 214 is formed perpendicularly to the end portion 212a. In addition, on the shaft portion 212, a cylindrical portion 216 is provided on the side opposite to the side where the flange portion 214 is provided, serving as a portion for riveting with other components (e.g., internal terminals).

[0068] In this embodiment, the second component 220 is plate-shaped. The second component 220 has a recess 222 on one surface 221 to receive the flange portion 214 of the first component 210. The recess 222 has a shape corresponding to the outer shape of the flange portion 214. The bottom 222a of the recess 222 is a circular shape corresponding to the shape of the end portion 212a of the first component 210. The side peripheral surface 222b of the recess 222 is formed perpendicularly from the bottom 222a toward the opening. The second component 220 has a recess 224 on another surface 223. In this embodiment, the recess 224 is formed by cutting a cuboid shape from the other surface 223. The side peripheral surface 224b of the recess 224 is formed perpendicularly from the bottom 224a toward the opening. Furthermore, the shape of the recess 224 is not particularly limited. In addition to a cuboid shape, it can also be a cube, hemisphere, cylinder, triangular pyramid, prism, pyramid, frustum pyramid, etc.

[0069] The first component 210 and the second component 220 have a metal joint 230 joined by metal bonding at their overlapping boundary surfaces. In this embodiment, the end face (upper surface) of the first component 210 on the side where the flange portion 214 is formed is joined to the bottom 222a of the recess 222 formed on the surface 221 of the second component 220 by metal bonding. In this embodiment, the metal joint 230 is formed by ultrasonic bonding. Specifically, the metal joint 230 is formed at the boundary surface between the first component 210 and the second component by pressing an ultrasonic bonding die against the bottom 224a of the recess 224 of the second component 220 and applying ultrasonic vibration. In this embodiment, the bottom 224a of the recess 224 has a recessed contact portion 226 formed as a pressing die (in... Figure 6 (The specific shape is omitted in the text). Furthermore, the method of forming the metal joint 230 is not limited to this; for example, it can be formed by resistance welding.

[0070] like Figure 5 and 6 As shown, on the surface 223 of the second component 220 opposite to the surface 221 where the metal joint 230 is formed, a raised portion 225 is formed around the metal joint 230. By forming the raised portion 225, when an external component (e.g., busbar 93) beam is welded to the surface 223 of the second component 220, it is possible to prevent the beam from directly irradiating the contact portion 226. As a result, thermal degradation of the metal joint 230 can be reduced.

[0071] like Figure 5As shown, in this embodiment, a protrusion 225 is formed at the bottom 224a of the recess 224. The maximum height T1 of the protrusion 225 is designed not to exceed the height (depth) T2 of the recess 224. This allows an external component (e.g., a busbar 93) to overlap the surface 223 of the second component 220 in a manner that closes the recess 224. Furthermore, the height T1 of the protrusion 225 refers to its height from the bottom 224a of the recess 224. Additionally, the height (depth) T2 of the recess 224 refers to the height from the bottom 224a of the recess 224 to the surface 223 of the second component 220 having the recess 224. In this embodiment, the height of the side peripheral surface 224b of the recess 224 is the height (depth) T2 of the recess 224.

[0072] While not specifically limited, if the height T1 of the raised portion 225 is too low, the obstruction of beam illumination may become insufficient. Therefore, the average value of the height T1 of the raised portion 225 can be, for example, 0.1 mm or more, or 0.15 mm or more, or 0.2 mm or more. On the other hand, if the height T1 of the raised portion 225 is too high, the strength of the raised portion 225 is compromised, and it is prone to detachment from the second component 220. Therefore, the average value of the height T1 of the raised portion 225 can be, for example, 0.5 mm or less, or 0.45 mm or less, or 0.4 mm or less. Furthermore, the average value of the height T1 of the raised portion 225 can be, for example, the average value when the heights of the raised portions 225 at 20 or more locations are randomly measured.

[0073] Figure 7 This is a schematic diagram showing the structure when the terminal component 200 is used as the external terminal 43b of the negative terminal 43 of a single cell in the battery pack 90. ​​A busbar 93 is beam-welded to the surface 223 of the second component 220. In this embodiment, welded portions 99 are formed at two locations. Furthermore, in this embodiment, the busbar 93 is made of aluminum. As shown, a raised portion 225 is located between the metal joint 230 and the welded portion 99.

[0074] With prolonged use of the battery pack 90 or the lithium-ion secondary battery 10, a portion of the raised portion 225 may detach from the surface. Therefore, it is preferable to form the weld portion 99 near the recess 224 to prevent the detached portion from leaking out of the recess 224. This allows for a more reliable sealing of the recess 224. While the closer the weld portion 99 is to the recess 224, the easier it is to irradiate the recess 224 with a light beam, the raised portion 225 reduces the amount of light beam irradiation directed to the contact portion 226, thereby reducing heat input to the metal joint 230. Furthermore, the type of beam welding is not particularly limited; examples include laser welding and electron beam welding.

[0075] like Figure 6As shown, in this embodiment, the raised portion 225 is continuously formed to surround the contact portion 226. In other words, the raised portion 225 is formed to surround the metal joint portion 230. Therefore, regardless of the position of the external component being beam-welded, the amount of light irradiated onto the contact portion 226 can be appropriately reduced, thereby reducing heat input to the metal joint portion 230. Furthermore, the raised portion 225 only needs to be formed in at least a predetermined direction near the contact portion 226 where beam welding is performed. Therefore, the raised portion 225 can also be formed discontinuously.

[0076] In addition, such as Figure 5 and 6 As shown, the raised portion 225 can have a flat upper surface 225a. By having an upper surface 225a, the thickness (width) of the raised portion 225 is increased, thus more appropriately suppressing the irradiation of the light beam toward the contact portion 226. In addition, according to this structure, the strength of the raised portion 225 is increased, so the raised portion 225 is less likely to detach from the surface.

[0077] like Figure 6 As shown, in this embodiment, the raised portion 225 is formed into a rectangular shape with rounded corners in a top view. However, the shape of the raised portion 225 in the top view is not particularly limited, and it can be rectangular, square, ring-shaped, etc., and these shapes can also be formed intermittently.

[0078] The above description describes one embodiment of the terminal component 200, but this embodiment is merely an example, and it can be implemented in various other ways. For example, in the above embodiment, the first component 210 of the terminal component 200 is made of copper, the second component 220 is made of aluminum, and the busbar 93 is made of aluminum, but it is not particularly limited to this. The first component 210, the second component 220, and the busbar may also be made of copper, a copper-based alloy, aluminum, an aluminum-based alloy, nickel, etc., respectively. In addition, the first component 210 and the second component 220 may be made of different metals or the same type of metal. Furthermore, the terminal component 200 may also be used as the external terminal 42b of the positive terminal 42.

[0079] Furthermore, in this specification, "aluminum-based alloy" refers to an alloy composed of at least 50% aluminum. Other elements that this aluminum material may contain are not particularly limited, but examples include silicon, iron, copper, manganese, magnesium, zinc, chromium, titanium, lead, and zirconium. Similarly, "copper-based alloy" refers to an alloy composed of at least 50% copper. Other elements that this same material may contain are not particularly limited, but examples include silicon, iron, manganese, magnesium, zinc, chromium, titanium, lead, tin, phosphorus, aluminum, nickel, cobalt, beryllium, and zirconium.

[0080] Hereinafter, a preferred example of a method for manufacturing the terminal component 200 will be described. As an example, ultrasonic bonding using the ultrasonic bonding mold 100 described later can be used. In this method, the raised portion 225 can be formed simultaneously when forming the metal joint 230 between the first component 210 and the second component 220. Therefore, no additional step for forming the raised portion 225 is required, thus reducing time and cost. Hereinafter, the structure of the mold 100 and ultrasonic bonding using the mold 100 will be described.

[0081] exist Figures 8-10 The diagram shows one embodiment of the mold head 100. Figure 8 It is a three-dimensional diagram schematically representing the structure of the mold head 100. Figure 9 It is a top view schematically showing the structure of the mold head 100. Figure 10 This is a schematic side view illustrating the structure of the mold head 100. Furthermore, in the following description, the reference numerals F, B, L, R, U, and D in the drawings represent front, rear, left, right, top, and bottom, respectively. However, these descriptions are merely for convenience and do not impose any limitations on the arrangement.

[0082] like Figure 8 As shown, the die head 100 includes a base portion 110, a platform portion 130, and a pressing portion 150. By mounting the die head 100 to an ultrasonic vibrator (not shown), ultrasonic vibration can be performed in a specified direction. This allows ultrasonic vibration to be transmitted to the materials to be joined, achieving ultrasonic bonding. Furthermore, in the following description, the direction of ultrasonic vibration (hereinafter also simply referred to as the "vibration direction") will be described as the front-to-back direction.

[0083] The base portion 110 is the part connected to the ultrasonic vibrator. For example... Figure 9 As shown, the base portion 110 has a rectangular surface in a top view. A platform portion 130 is formed from the surface (upper surface) of the base portion 110. In a top view, the upper surface of the base portion 110 has an area wider than the platform portion 130, and has an exposed surface 112 where the platform portion 130 is not formed. In this embodiment, the base portion 110 is formed in a cuboid shape, but the overall shape of the base portion 110 is not particularly limited as long as it has an upper surface for the platform portion 130 to stand on. Furthermore, the shape of the surface of the platform portion 130 of the base portion 110 in a top view is not particularly limited; for example, it can be polygonal, circular, elliptical, etc. The base portion 110 can be made of any material used in conventional molds, such as superhard alloy, mold steel, high-speed steel, etc.

[0084] The platform portion 130 is the portion that rises from the surface of the base portion 110 and exists between the base portion 110 and the pressing portion 150. For example... Figure 9As shown, in a top view, a platform 130 is formed within an area narrower than the surface of the base portion 110. Furthermore, in this embodiment, in a top view, the upper surface 131 of the platform 130 has an area wider than the pressing portion 150. Here, the upper surface 131 of the platform 130 is parallel to the upper surface of the base portion 110.

[0085] like Figure 9 As shown, in this embodiment, the platform 130 has a hexagonal shape with a long side in the left-right direction when viewed from above. A peripheral wall 132 is formed between the upper surface 131 of the platform 130 and the upper surface of the base 110. The peripheral wall 132 has a pair of wide surfaces 132a and four narrow surfaces 132b facing each other in the vibration direction.

[0086] Furthermore, the shape of the platform 130 is not particularly limited; from a top view, it can be polygonal, circular, elliptical, etc. Additionally, the platform 130 can be made of the same material as the base 110. Furthermore, the portions of the platform 130 that may come into contact with the materials being joined (e.g., the upper surface 131 of the platform 130) can be coated with diamond-like carbon (DLC) coatings, titanium nitride (TiN) coatings, etc. This reduces the condensation of the metal constituting the joined materials (e.g., aluminum). Additionally, the coating treatment improves wear resistance.

[0087] The crimping portion 150 is composed of a plurality of protrusions 152 extending from the upper surface 131 of the platform portion 130. The plurality of protrusions 152 are arranged on the upper surface 131 of the platform portion 130. The crimping portion 150 is the portion that is pressed against the materials to be joined and transmits ultrasonic vibrations to the materials to be joined.

[0088] like Figure 8 and 9 As shown, in this embodiment, the crimping portion 150 has 10 protrusions 152. Furthermore, the number of protrusions 152 can be two or more, for example, five or more, eight or more, ten or more, or twelve or more. The number of protrusions 152 can be appropriately varied depending on the area to be ultrasonically bonded, and no particular upper limit is set. For example, it can be less than 100, less than 50, or less than 20. Furthermore, the protrusions 152 can be made of the same material as the base portion 110. Additionally, the protrusions 152 can be coated with the same material as the platform portion 130.

[0089] like Figures 8-10As shown, in this embodiment, the protrusion 152 is formed in the shape of a frustum of a square pyramid. Here, the protrusion 152 has a square upper surface 152a, a square base 152b, and four side surfaces 152c formed between the upper surface 152a and the base 152b. The upper surface 152a has a narrower area than the base 152b. Furthermore, the shape of the protrusion 152 is not limited to this; for example, it can be a pyramid shape, such as a triangular pyramid, a square pyramid, a hexagonal pyramid, or a frustum of a triangular pyramid or a hexagonal pyramid. Additionally, the shapes of the multiple protrusions 152 may not all be identical.

[0090] like Figure 9 As shown, in a top view, at least a portion of the periphery of the arrangement of the plurality of protrusions 152 is formed with a zigzag-shaped portion 154. In this embodiment, the zigzag-shaped portion 154 is formed by the bottom surface 152b of three protrusions 152 arranged in a direction perpendicular to the vibration direction. Figure 8 and 9 As shown, the zigzag part 154 typically has a zigzag shape formed by connecting the vertices with straight lines, but it can also be a shape in which the vertices are rounded.

[0091] The zigzag portion 154 is formed by arranging at least two protrusions 152, but the number of protrusions 152 constituting the zigzag portion 154 is not particularly limited, for example, it can be 3 or more, 4 or more, or 5 or more. In addition, the number of protrusions 152 constituting the zigzag portion 154 is limited by the area of ​​the upper surface 131 of the platform portion 130. Although it is not particularly limited, it can be, for example, 20 or less, 15 or less, or 10 or less.

[0092] Figure 11A and 11B This is a schematic diagram that generally illustrates the process of joining the first component 210 and the second component 220 of the terminal component 200 by ultrasonic bonding. Figure 11A This is a schematic diagram showing the structure before ultrasonic bonding. Figure 11B This is a schematic diagram illustrating the ultrasonic bonding process.

[0093] like Figure 11A and 11BAs shown, ultrasonic bonding is performed with the first component 210 and the second component 220 having a recess 224 overlapping. A die head 100 is mounted on an ultrasonic oscillator (not shown). The pressing portion 150 of the die head 100 is pressed against the bottom 224a of the recess 224 of the second component 220. Meanwhile, the first component 210 is pressed against the anvil 300 from the cylindrical portion 216 side. Thus, the first component 210 and the second component 220 are clamped together by the die head 100 and the anvil 300. Furthermore, ultrasonic vibrations generated by the ultrasonic oscillator (in the figure, the front-to-back direction is the vibration direction) are transmitted to the die head 100, and the second component 220 is pressurized and subjected to ultrasonic vibration by the die head 100, thereby bonding the first component 210 and the second component 220 to form a metal joint 230.

[0094] like Figure 11B As shown, a raised portion 225 is formed by the accumulation of burrs generated during ultrasonic bonding. The mold head 100 has an exposed surface 112 of a platform portion 130 and a base portion 110. Therefore, when the burrs generated around the contact portion 226 extend in the height direction, they are pressed in by the exposed surface 112, thus controlling the height of the raised portion 225. As a result, the height T1 of the raised portion 225 can be adjusted to not exceed the height (depth) T2 of the recess 224.

[0095] Furthermore, the mold head 100 has a zigzag portion 154 around the periphery of the arrangement of the plurality of protrusions 152, thus guiding the burrs generated during ultrasonic bonding toward the valley of the zigzag portion 154. This suppresses the formation of burrs that extend horizontally, thus preventing them from easily elongating in the vertical direction. Moreover, the burrs elongating in the vertical direction are easily held in place by the exposed surface 112. As a result, the protrusion 225 can be formed to a height below the desired level.

[0096] Furthermore, various conditions for ultrasonic bonding can be appropriately set according to the metal type and size of the materials to be bonded (here, the first component 210 and the second component 220), the shape of the mold head 100, etc., and are therefore not particularly limited. For example, when the first component 210 is copper and the second component 220 is aluminum, the amplitude can be about 20 μm to 50 μm, the frequency can be about 19 kHz to 21 kHz, the load on which the mold head 100 is pressed against the materials to be bonded can be 30 N to 200 N, and the amount of energy supplied to the materials to be bonded can be about 30 J to 200 J.

[0097] In this way, a terminal component 200 having a raised portion 225 can be manufactured. Hereinafter, the structure of the mold head 100 that can form the raised portion 225 more appropriately will be described.

[0098] Preferably, the zigzag portion 154 of the die head 100 is formed along at least one of the vibration direction (here, the front-to-back direction) and the direction perpendicular to the vibration direction (here, the left-to-right direction), and more preferably, the zigzag portion 154 is formed along the direction perpendicular to the vibration direction. Since burrs tend to be generated in the vibration direction, by forming the zigzag portion 154 along the direction perpendicular to the vibration direction, the bulge 225 on the vibration direction side of the contact portion 226 can be formed more stably.

[0099] Furthermore, preferably, in a top view, the periphery of the arrangement of the plurality of protrusions 152 does not have either an edge extending in the vibration direction or an edge extending in a direction perpendicular to the vibration direction. With this structure, before the side surface 152c of the protrusion 152 contacts the material to be joined, the edge (corner) connecting the upper surface 152a and the bottom surface 152b of the protrusion 152 contacts the material to be joined. This suppresses the straight extrusion of burrs in the vibration direction, thus more appropriately controlling the burrs and enabling the formation of a more stable shape of the protrusion 225.

[0100] During ultrasonic bonding, burrs accumulate in the burr accumulation portion 170 of the mold head 100, forming a raised portion 225. That is, the shape of the raised portion 225 can be largely controlled by the shape of the burr accumulation portion 170. For example, the height T1 of the raised portion 225 can be controlled to be below the height T3 of the platform portion. Furthermore, since the upper surface 225a of the raised portion 225 is formed by contact with the exposed surface 112, if the exposed surface 112 is flat, the upper surface 225a of the raised portion 225 can be formed flatly.

[0101] Furthermore, generally speaking, the rough edge accumulation portion 170 refers to the space above the exposed surface 112 up to the height T3 of the platform portion 130 (see reference). Figure 10 Additionally, the height T3 of the platform 130 refers to the height from the upper surface (exposed surface 112) of the base 110.

[0102] Preferably, the volume of the burr accumulation portion 170 is greater than the volume of the entire protrusion 152 (pressing portion 150). It is presumed that the volume of the burr generated by ultrasonic bonding is the amount of volume that enters the material being bonded in the die 100. That is, it is presumed to be the amount of burr that can generate the volume of the entire protrusion 152. Therefore, by making the volume of the burr accumulation portion 170 greater than the volume of the entire protrusion 152, the height of the burr can be controlled more reliably. Generally, the volume of the burr accumulation portion 170 can be calculated by (area of ​​exposed surface 112) × (height T3 of platform 130). However, the method for calculating the volume can be appropriately changed according to the shape of the exposed surface 112, the shape of the platform 130, etc.

[0103] The ratio of the height T3 of the platform 130 to the height T4 of the protrusion 152 (pressing portion 150) can be, for example, 5:1 to 1:1, preferably 4:1 to 1:1, more preferably 3:1 to 1:1, and for example, 2:1 to 1:1. If the height T3 of the platform 130 is too large relative to the height T4 of the protrusion 152, the rigidity decreases, and the durability of the platform 130 may decrease. Furthermore, if the height T3 of the platform 130 is too small relative to the height T4 of the protrusion 152, the burrs pressed by the exposed surface 112 may extend horizontally, potentially becoming disorderly expanding burrs, which is therefore undesirable. Additionally, the height T4 of the protrusion 152 refers to the height from the upper surface 131 of the platform 130 (the bottom surface 152b of the protrusion 152) to the upper surface 152a of the protrusion 152 (the apex if the protrusion 152 is a pyramid).

[0104] Furthermore, although not specifically limited, the height T3 of the platform 130 can be, for example, 0.1 mm or more, or 0.3 mm or more. In addition, the height T3 of the platform 130 can be, for example, 1.5 mm or less, or 1 mm or less, or 0.5 mm or less.

[0105] If the height T4 of the protrusion 152 is too low, the contact area between the protrusion 152 and the material being joined increases, and components of the material being joined (e.g., aluminum) tend to solidify on the protrusion 152. Therefore, the height T4 of the protrusion 152 can be, for example, 0.03 mm or more, and can be 0.1 mm or more, or 0.2 mm or more. Conversely, if the height T4 of the protrusion 152 is too high, the rigidity of the protrusion 152 decreases, thus reducing its durability. Therefore, the height T4 of the protrusion 152 can be, for example, 0.3 mm or less, and can be 0.25 mm or less. Furthermore, the height T4 of the protrusion 152 can be appropriately varied depending on the material and thickness of the material being joined, and the conditions of ultrasonic bonding, and is therefore not limited to the above-mentioned numerical ranges.

[0106] like Figure 8 and 9 As shown, the protrusions 152 are preferably arranged adjacent to each other in a manner that does not create flat grooves between them. In other words, the bottom surfaces 152b of the protrusions 152 are adjacent to each other without gaps. This reduces the amount of burrs entering between the protrusions 152, making it easier to accumulate burrs around the contact portion 226, thus appropriately forming the raised portion 225. Furthermore, the arrangement of the protrusions 152 is not limited to this; for example, gaps (grooves) may exist between the protrusions 152.

[0107] like Figure 9As shown, in this embodiment, in a top view, the exposed surface 112 of the base portion 110 is provided around the entire circumference of the platform portion 130. In other words, the platform portion 130 is formed at a position inside the end of the surface of the base portion 110. As a result, the height T1 of the raised portion 225 can be appropriately controlled in any direction around the ultrasonic joint.

[0108] like Figure 10 As shown, the width W1 of the exposed surface 112 relative to the height T4 of the protrusion 152 can be, for example, more than 1 / 3, more than 1 / 2, more than 1, more than 2, or more than 4 times. This allows for more reliable accumulation of burrs in the burr accumulation portion 170 and appropriate control of the burr height. Here, the width W1 of the exposed surface 112 refers to the distance perpendicularly connecting the peripheral wall 132 of the platform 130 to the shape of the exposed surface, and may vary depending on each face of the peripheral wall 132 (here, the wide face 132a and the narrow face 132b). Furthermore, the width W1 of the exposed surface 112 is not limited to the aforementioned ratio and can be appropriately varied according to the height T3 of the platform 130. In other words, the volume of the burr accumulation portion 170 can be designed to be larger than the overall volume of the protrusion 152 (the pressing portion 150).

[0109] Additionally, the width of the exposed surface 112 may be uneven around the entire perimeter of the platform 130. For example, for burrs, more burrs are generated relative to the vibration direction, so it is preferable that the width of the exposed surface 112 in the vibration direction is wider than the width in the direction perpendicular to the vibration direction (left-right direction in the figure).

[0110] The above describes the manufacturing method of the terminal component 200 based on ultrasonic bonding using the die head 100. However, the method for forming the raised portion 225 is not limited to this; for example, it can also be formed by stamping.

[0111] The above descriptions of the disclosed technology, with specific examples, are merely illustrative and do not limit the scope of the claims. The disclosed technology includes various modifications and alterations to the above-described specific examples.

Claims

1. A terminal component comprising a first metal component and a plate-shaped second metal component, wherein, A metal joint is formed at the boundary surface where the first component and the second component overlap, and the metal joint is joined by metal bonding. On the surface of the second component opposite to the boundary surface, a raised portion is formed from that surface. The second component has a recess on the side opposite to the boundary surface, and the raised portion is formed within the recess. The maximum height of the raised portion from the bottom of the recess does not exceed the height from the bottom of the recess to the surface having the recess. The raised portion is continuously formed in a manner that surrounds the metal joint.

2. The terminal component according to claim 1, wherein, The raised portion has a flat upper surface.

3. The terminal component according to claim 1 or 2, wherein, The metal joint is an ultrasonic joint that is joined by ultrasonic bonding.

4. A secondary battery, comprising: Electrode body, including positive and negative electrodes; A battery case that houses the electrode body inside; The positive terminal is electrically connected to the positive electrode; and The negative terminal is electrically connected to the negative terminal. in, At least one of the positive terminal and the negative terminal includes the terminal component as described in any one of claims 1 to 3.

5. A battery pack, comprising multiple individual cells electrically connected and arranged together, wherein, The secondary battery as described in claim 4 is at least one of the plurality of single batteries.

6. The battery pack according to claim 5, wherein, The multiple individual cells are electrically connected via a busbar, with the positive terminal of one individual cell connected to the negative terminal of another individual cell respectively. Here, the terminal component has a welded portion for welding the second component and the busbar beam electrically connected to the second component. The raised portion is located between the metal joint and the weld.

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