Battery and method of manufacturing the same, and forming mold

Abstract

The present application provides a kind of battery and its manufacturing method and forming die.The riveting joint process includes: preparing the forming die including the first taper portion (910) inclined at the first angle and the second taper portion (920) inclined at the second angle larger than the first angle;And the first taper portion (910) of forming die (900) is opposite to the front end of terminal member, makes forming die (900) move along the central axis, inserts forming die (900) into the cylindrical portion (400β) formed in the front end of terminal member (400), the first part of cylindrical portion (400β) is pressed to the radial outside by the first taper portion (910), and the second part of cylindrical portion (400β) is pressed to the radial outside by the second taper portion (920), so that the front end of terminal member (400) is expanded.

Description

Technical Field

[0001] This invention relates to a battery, its manufacturing method, and a molding die. Background Technology

[0002] Batteries with a structure in which electrode terminals and current collectors are joined by riveting are known in the past. Such batteries are shown, for example, in Japanese Patent Application Publication No. 2017-10743.

[0003] Depending on the shape of the forming die used for riveting, the shape of the riveted joint may be unstable. In cases of unstable riveted joint shape, the strain of the riveted components may locally increase, potentially exceeding permissible limits. Conventional processing methods may not be sufficient to address these issues. Summary of the Invention

[0004] The purpose of this invention is to provide a battery with a shape-stable riveted joint, a method for manufacturing the same, and a forming mold for the manufacturing method.

[0005] The battery of the present invention comprises: a conductive member having a through hole; and a terminal member inserted into the through hole, having a front end portion exposed on the conductive member. A riveting joint is formed between the front end portion of the terminal member and the conductive member. The front end portion of the terminal member includes a recess having an inner circumferential surface. A bend is formed on the inner circumferential surface such that the inclination of the inner circumferential surface relative to the central axis of the terminal member changes.

[0006] The battery manufacturing method of the present invention includes: a step of inserting a terminal member into a through hole of a conductive member; and a step of riveting the front end of the terminal member to the conductive member. The riveting step includes: preparing a forming mold including a first tapered portion and a second tapered portion, the first tapered portion being inclined at a first angle relative to the central axis of the terminal member, and the second tapered portion being disposed on the large-diameter side of the first tapered portion and inclined at a second angle larger than the first angle relative to the central axis; and positioning the first tapered portion of the forming mold toward the front end of the terminal member, moving the forming mold along the central axis, inserting the forming mold into a cylindrical portion formed at the front end of the terminal member, pushing a first portion of the cylindrical portion radially outward by the first tapered portion, and pushing a second portion of the cylindrical portion radially outward by the second tapered portion, thereby expanding the diameter of the front end of the terminal member.

[0007] The forming mold of the present invention is for riveting a first component and a second component together and is insertable into a cylindrical portion formed at the front end of the second component. The first component has a through hole, and the second component is inserted into the through hole, having a front end portion exposed on the first component. The forming mold includes a first tapered portion and a second tapered portion. The first tapered portion is inclined at a first angle relative to the central axis of the second component, and the second tapered portion is disposed on the large-diameter side of the first tapered portion and is inclined at a second angle relative to the central axis at a second angle larger than the first angle.

[0008] The above and other objects, features, aspects and advantages of the invention will become apparent from the following detailed description of the invention, taken in conjunction with the accompanying drawings. Attached Figure Description

[0009] Figure 1 It is a 3D diagram of a square secondary battery.

[0010] Figure 2 yes Figure 1 Sectional view II-II.

[0011] Figure 3 This is a top view of the positive plate that makes up the electrode body.

[0012] Figure 4 This is a top view of the negative electrode plate that makes up the electrode body.

[0013] Figure 5 This is a top view showing an electrode body composed of a positive plate and a negative plate.

[0014] Figure 6 This diagram shows the connection structure between the electrode body and the positive and negative current collector components.

[0015] Figure 7 This diagram shows the installation structure of the positive and negative current collector components onto the sealing plate.

[0016] Figure 8 yes Figure 7 Sectional view of VIII-VIII.

[0017] Figure 9 yes Figure 7 IX-IX sectional view.

[0018] Figure 10 This is a diagram showing the connection state between the sealing plate and the electrode body.

[0019] Figure 11 This is a diagram illustrating the first step of a riveting joint in one embodiment.

[0020] Figure 12 yes Figure 11 A magnified view of the front end of the mold.

[0021] Figure 13 This is a diagram illustrating the second step of riveting joint in one embodiment.

[0022] Figure 14 yes Figure 13 A magnified view of the front end of the mold.

[0023] Figure 15 This is a diagram illustrating the third step of riveting joint in one embodiment.

[0024] Figure 16 yes Figure 15 A magnified view of the riveted joint in the image.

[0025] Figure 17 This is a diagram showing the first step of the riveting joint in a comparative example.

[0026] Figure 18 yes Figure 17 A magnified view of the front end of the mold.

[0027] Figure 19 This is a diagram showing the second step of the riveting joint in a comparative example.

[0028] Figure 20 yes Figure 19 A magnified view of the front end of the mold.

[0029] Figure 21 This is a diagram showing the third step of the riveting joint in a comparative example.

[0030] Figure 22 yes Figure 21 A magnified view of the riveted joint in the image.

[0031] Figure 23 This is a schematic diagram illustrating the riveting joint of one embodiment and a comparative example.

[0032] Figure 24 It means from Figure 23 A diagram of a riveting joint according to one embodiment is extracted from the image.

[0033] Figure 25 It means from Figure 23 The diagram shows the riveting joint of the comparative example extracted from the image.

[0034] Figure 26 This diagram illustrates the stress distribution during the riveting process.

[0035] Figure 27 This is a graph showing the relationship between the riveting diameter and the maximum equivalent total strain.

[0036] Figure 28This is a diagram illustrating the shape of the riveting portion midway through a riveting joint in one embodiment.

[0037] Figure 29 This is a diagram illustrating the shape of the riveted portion after riveting in one embodiment.

[0038] Figure 30 This is a diagram illustrating the shape of the riveted portion midway through the riveting joint in the comparative example.

[0039] Figure 31 This is a diagram used to illustrate the shape of the riveted part after the comparative example is riveted together.

[0040] Figure 32 This is a diagram showing the structure of the riveted parts on the outside of the battery casing. Detailed Implementation

[0041] The embodiments of the present invention will be described below. Furthermore, sometimes the same or equivalent parts are labeled with the same reference numerals, and their description will not be repeated.

[0042] Furthermore, in the embodiments described below, when numbers, quantities, etc., are mentioned, the scope of the present invention is not necessarily limited to those numbers, quantities, etc., unless specifically stated otherwise. Additionally, in the embodiments described below, each constituent element is not necessarily essential to the present invention, unless specifically stated otherwise.

[0043] Furthermore, in this specification, the terms "comprise," "include," and "have" are open-ended. That is, when a structure is included, it may or may not include other structures besides that structure. Additionally, the present invention is not necessarily limited to achieving all the effects mentioned in this embodiment.

[0044] In this specification, "battery" is not limited to lithium-ion batteries and may include other batteries such as nickel-metal hydride batteries. In this specification, "electrode" can be a general term for both positive and negative electrodes. Additionally, "electrode plate" can be a general term for both positive and negative electrode plates.

[0045] Figure 1 This is a 3D view of a square secondary battery 1. Figure 2 yes Figure 1 Sectional view II-II.

[0046] like Figure 1 , Figure 2 As shown, the square secondary battery 1 includes a battery casing 100, an electrode body 200, an insulating sheet 300, a positive terminal 400, a negative terminal 500, a positive current collector 600, a negative current collector 700, and a cover member 800.

[0047] The battery casing 100 consists of a square outer body 110 with an opening and a bottomed rectangular tube shape, and a sealing plate 120 that seals the opening of the square outer body 110. The square outer body 110 and the sealing plate 120 are preferably made of metal, preferably aluminum or aluminum alloy.

[0048] An electrolyte injection hole 121 is provided on the sealing plate 120. After electrolyte is injected into the battery housing 100 through the electrolyte injection hole 121, the electrolyte injection hole 121 is sealed by the sealing member 122. As the sealing member 122, for example, a hollow rivet and other metal components can be used.

[0049] A gas discharge valve 123 is provided on the sealing plate 120. The gas discharge valve 123 breaks when the pressure inside the battery housing 100 reaches a specified value. As a result, the gas inside the battery housing 100 is discharged to the outside of the battery housing 100.

[0050] The electrode body 200 is housed together with the electrolyte within the battery casing 100. The electrode body 200 is formed by stacking a positive electrode plate and a negative electrode plate separated by a separator. A resin insulating sheet 300 is disposed between the electrode body 200 and the square outer casing 110.

[0051] A positive electrode tab 210A and a negative electrode tab 210B are provided at the end of the electrode body 200 on the sealing plate 120 side.

[0052] The positive electrode tab 210A and the positive terminal 400 are electrically connected via the positive current collector 600. The positive current collector 600 includes a first positive current collector 610 and a second positive current collector 620. Alternatively, the positive current collector 600 may be a single component. The positive current collector 600 is preferably made of metal, more preferably of aluminum or an aluminum alloy.

[0053] The negative electrode tab 210B and the negative terminal 500 are electrically connected via a negative current collector 700. The negative current collector 700 includes a first negative current collector 710 and a second negative current collector 720. Alternatively, the negative current collector 700 may be a single component. The negative current collector 700 is preferably made of metal, more preferably of copper or a copper alloy.

[0054] The positive terminal 400 is fixed to the sealing plate 120 via an external resin insulating member 410. The negative terminal 500 is fixed to the sealing plate 120 via an external resin insulating member 510.

[0055] The positive terminal 400 is preferably made of metal, more preferably of aluminum or an aluminum alloy. The negative terminal 500 is preferably made of metal, more preferably of copper or a copper alloy. The negative terminal 500 may also have a region made of copper or a copper alloy disposed on the inner side of the battery housing 100 and a region made of aluminum or an aluminum alloy disposed on the outer side of the battery housing 100.

[0056] The cover member 800 is located between the first positive current collector 610 and the electrode body 200. The cover member 800 may also be provided on the negative current collector side. In addition, the cover member 800 is not a necessary component and can be omitted appropriately.

[0057] Figure 3 This is a top view of the positive electrode plate 200A constituting the electrode body 200. The positive electrode plate 200A has a main body portion 220A, on which a positive electrode active material mixture layer comprising a positive electrode active material (e.g., lithium nickel cobalt manganese composite oxide), a binder material (e.g., polyvinylidene fluoride (PVdF)), and a conductive material (e.g., carbon material) is formed on both sides of a positive electrode core made of rectangular aluminum foil. The positive electrode core protrudes from the end edge of the main body portion, and this protruding positive electrode core constitutes a positive electrode tab 210A. In the portion of the positive electrode tab 210A adjacent to the main body portion 220A, a positive electrode protective layer 230A comprising alumina particles, a binder material, and a conductive material is provided. The positive electrode protective layer 230A has a resistance greater than that of the positive electrode active material mixture layer. The positive electrode active material mixture layer may not contain conductive material. The positive electrode protective layer 230A may also be omitted.

[0058] Figure 4 This is a top view of the negative electrode plate 200B constituting the electrode body 200. The negative electrode plate 200B has a main body portion 220B, on which negative electrode active material layers are formed on both sides of a negative electrode core made of rectangular copper foil. The negative electrode core protrudes from the end edge of the main body portion 220B, and this protruding negative electrode core constitutes a negative electrode tab 210B.

[0059] Figure 5 This is a top view showing the electrode body 200 composed of a positive electrode plate 200A and a negative electrode plate 200B. (Example) Figure 5 As shown, the electrode body 200 is fabricated with positive electrode tabs 210A of each positive electrode plate 200A stacked at one end, and negative electrode tabs 210B of each negative electrode plate 200B stacked thereon. For example, approximately 50 sheets of each of the positive electrode plate 200A and negative electrode plate 200B are overlapped. The positive electrode plate 200A and negative electrode plate 200B are alternately stacked with a rectangular separator made of polyolefin in between. Alternatively, the long strip separator can be folded in a zigzag manner for use.

[0060] Figure 6 This diagram shows the connection structure between the electrode body 200 and the positive current collector 600 and the negative current collector 700. (See diagram below.) Figure 6 As shown, the electrode body 200 is composed of a first electrode body element 201 (first stacked group) and a second electrode body element 202 (second stacked group). A separator is also disposed on the outer surface of the first electrode body element 201 and the second electrode body element 202. The first electrode body element 201 and the second electrode body element 202 can be fixed in a stacked state, for example, by means of adhesive tape. Alternatively, an adhesive layer can be provided on each positive electrode plate 200A, negative electrode plate 200B, and separator to bond the separator and positive electrode plate 200A respectively, and to bond the separator and negative electrode plate 200B respectively.

[0061] The plurality of positive electrode tabs 210A of the first electrode element 201 constitute a first positive electrode tab group 211A. The plurality of negative electrode tabs 210B of the first electrode element 201 constitute a first negative electrode tab group 211B. The plurality of positive electrode tabs 210A of the second electrode element 202 constitute a second positive electrode tab group 212A. The plurality of negative electrode tabs 210B of the second electrode element 202 constitute a second negative electrode tab group 212B.

[0062] A second positive current collector 620 and a second negative current collector 720 are disposed between the first electrode element 201 and the second electrode element 202. The second positive current collector 620 has a first opening 620A and a second opening 620B. A first positive electrode tab group 211A and a second positive electrode tab group 212A are welded to the second positive current collector 620 to form a welded connection portion 213. A first negative electrode tab group 211B and a second negative electrode tab group 212B are welded to the second negative current collector 720 to form a welded connection portion 213. The welded connection portion 213 can be formed, for example, by ultrasonic welding, resistance welding, laser welding, etc.

[0063] Figure 7 This is a diagram showing the installation structure of the positive current collector 600 and the negative current collector 700 mounted on the sealing plate 120. Figure 8 express Figure 7 Section VIII-VIII. Figure 9 express Figure 7 The IX-IX section.

[0064] First, refer to Figure 7 , Figure 8 The installation of the positive current collector 600 onto the sealing plate 120 is explained.

[0065] A resin-made external insulating member 410 is disposed on the outer surface of the sealing plate 120. A first positive current collector 610 and a resin-made insulating member 630 (positive current collector bracket) are disposed on the inner surface of the sealing plate 120. Next, the positive terminal 400 is inserted into the through hole of the external insulating member 410, the positive terminal mounting hole of the sealing plate 120, the through hole of the first positive current collector 610, and the through hole of the insulating member 630. Then, the riveting portion 400A located at the front end of the positive terminal 400 is riveted to the first positive current collector 610. Thus, the positive terminal 400, the external insulating member 410, the sealing plate 120, the first positive current collector 610, and the insulating member 630 are fixed. Furthermore, the riveted portions of the positive terminal 400 and the first positive current collector 610 are preferably welded together by laser welding or the like. In addition, the first positive current collector 610 has a countersunk hole 610A, and the riveting part 400A is disposed in the countersunk hole 610A.

[0066] Furthermore, the second positive current collector 620 is disposed on the insulating member 630 such that a portion of the second positive current collector 620 overlaps with the first positive current collector 610. The second positive current collector 620 is welded to the first positive current collector 610 through a first opening 620A provided in the second positive current collector 620 by means of laser welding or the like.

[0067] like Figure 8 As shown, the insulating member 630 has a cylindrical portion 630A protruding from the electrode body 200 side. The cylindrical portion 630A passes through the second opening 620B of the second positive current collector 620, and the hole portion 630B is defined to communicate with the electrolyte injection hole 121.

[0068] When installing the positive current collector 600 onto the sealing plate 120, firstly, the first positive current collector 610 is connected to the insulating member 630 on the sealing plate 120. Next, the second positive current collector 620, which is connected to the electrode body 200, is installed onto the first positive current collector 610. At this time, the second positive current collector 620 is positioned on the insulating member 630 such that a portion of it overlaps with the first positive current collector 610. Then, the area around the first opening 620A in the second positive current collector 620 is welded to the first positive current collector 610 using laser welding or the like.

[0069] Below, refer to Figure 7 and Figure 9 This describes the installation of the negative current collector 700 onto the sealing plate 120.

[0070] A resin-made external insulating member 510 is disposed on the outer surface of the sealing plate 120. A first negative current collector 710 and a resin-made insulating member 730 (negative current collector bracket) are disposed on the inner surface of the sealing plate 120. Next, the negative terminal 500 is inserted into the through hole of the external insulating member 510, the negative terminal mounting hole of the sealing plate 120, the through hole of the first negative current collector 710, and the through hole of the insulating member 730. Then, the riveting portion 500A located at the front end of the negative terminal 500 is riveted to the first negative current collector 710. Thus, the negative terminal 500, the external insulating member 510, the sealing plate 120, the first negative current collector 710, and the insulating member 730 are fixed. Furthermore, the riveted portions of the negative terminal 500 and the first negative current collector 710 are preferably welded together by laser welding or the like.

[0071] Furthermore, the second negative current collector 720 is disposed on the insulating member 730 such that a portion of the second negative current collector 720 overlaps with the first negative current collector 710. The second negative current collector 720 is welded to the first negative current collector 710 through a first opening 720A provided in the second negative current collector 720 by means of laser welding or the like.

[0072] When installing the negative electrode current collector 700 onto the sealing plate 120, firstly, the first negative electrode current collector 710 is connected to the insulating member 730 on the sealing plate 120. Next, the second negative electrode current collector 720, which is connected to the electrode body 200, is installed onto the first negative electrode current collector 710. At this time, the second negative electrode current collector 720 is positioned on the insulating member 730 such that a portion of it overlaps with the first negative electrode current collector 710. Then, the area around the first opening 720A in the second negative electrode current collector 720 is welded to the first negative electrode current collector 710 using laser welding or the like.

[0073] Figure 10 This diagram shows the connection state between the sealing plate 120 and the electrode body 200. As described above, the first electrode body element 201 and the second electrode body element 202 are mounted on the sealing plate 120 via the positive current collector 600 and the negative current collector 700. Thus, as... Figure 10 As shown, the first electrode element 201 and the second electrode element 202 are connected to the sealing plate 120, and the electrode 200 is electrically connected to the positive terminal 400 and the negative terminal 500.

[0074] from Figure 10 From the state shown, the first electrode element 201 and the second electrode element 202 are integrated into one unit. At this time, the first positive electrode tab group 211A and the second positive electrode tab group 212A are bent in opposite directions. The first negative electrode tab group 211B and the second negative electrode tab group 212B are bent in opposite directions.

[0075] The first electrode element 201 and the second electrode element 202 can be integrated into one piece using adhesive tape or the like. Alternatively, they can be integrated by placing the first electrode element 201 and the second electrode element 202 within an insulating sheet shaped like a box or bag. Furthermore, the first electrode element 201 and the second electrode element 202 can also be fixed by adhesive bonding.

[0076] The first electrode element 201 and the second electrode element 202, which are integrated into one unit, are surrounded by an insulating sheet 300 and inserted into the square outer casing 110. Then, a sealing plate 120 is welded to the square outer casing 110, and the opening of the square outer casing 110 is sealed by the sealing plate 120 to form a sealed battery casing 100.

[0077] Subsequently, a non-aqueous electrolyte is injected into the battery casing 100 through the electrolyte injection hole 121 provided in the sealing plate 120. As a non-aqueous electrolyte, for example, a non-aqueous electrolyte in which LiPF6 is dissolved at a concentration of 1.2 mol / L can be used, which is a non-aqueous solvent prepared by mixing ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) in a volume ratio (25°C) of 30:30:40.

[0078] After the non-aqueous electrolyte is injected, the electrolyte injection hole 121 is sealed by the sealing member 122. Through the implementation of the above steps, the square secondary battery 1 is completed.

[0079] Figure 11 This diagram illustrates the first step in forming the riveting portion 400A of this embodiment. Figure 12 yes Figure 11 A magnified view of the front end of the mold.

[0080] The riveting part 400A has a long axis along the X-axis and a short axis along the Y-axis. Figure 11 and Figure 12 (To be continued) Figures 13-22 Similarly, in the diagram, the section to the left of the center line represents the section along the major axis (X-axis direction), and the section to the right of the center line represents the section along the minor axis (Y-axis direction).

[0081] The riveting portion 400A in this embodiment has a planar shape in which a pair of straight portions and a pair of curved portions extending in the X-axis direction are arranged alternately in the circumferential direction. However, the planar shape of the riveting portion 400A may also be an elliptical shape, or a perfect circle shape without a major axis and a minor axis.

[0082] like Figure 11 , Figure 12As shown, the forming mold 900 has a first tapered portion 910 and a second tapered portion 920. The first tapered portion 910 is inclined at an angle relative to the central axis CL, and the second tapered portion 920 is disposed on the large diameter side of the first tapered portion 910 and is inclined at an angle greater than that of the first tapered portion 910 relative to the central axis CL.

[0083] The positive terminal 400 (terminal component) includes a cylindrical front end portion 400β having an inner circumferential surface 400α. A forming die 900 is used to rivet the first positive current collector 610 (first component) to the cylindrical front end portion 400β of the positive terminal 400 (second component) by inserting it into the cylindrical front end portion 400β of the positive terminal 400.

[0084] The forming die 900 is configured such that the first tapered portion 910 faces the cylindrical front end portion 400β of the positive terminal 400. Then, the first tapered portion 910 located on the front end side of the forming die 900 is inserted into the cylindrical front end portion 400β of the positive terminal 400 along the central axis CL.

[0085] Here, the minimum diameter (2×R2) of the first tapered portion 910 is more than 100 μm smaller than the aperture (2×R1) of the cylindrical front end portion 400β. As a result, even if the forming mold 900 produces some eccentricity, the front end of the first tapered portion 910 can be inserted into the cylindrical front end portion 400β of the positive terminal 400 without obstruction.

[0086] Figure 13 It means to continue Figure 11 , Figure 12 The diagram for the second process, Figure 14 yes Figure 13 A magnified view of the front end of the mold.

[0087] like Figure 13 , Figure 14 As shown, the forming mold 900, which is inserted into the cylindrical front end 400β of the positive terminal 400, is further inserted toward the inside of the cylindrical front end 400β.

[0088] At this time, the first tapered portion 910 located on the front end side of the forming mold 900 abuts against the cylindrical front end portion 400β at the abutting surface B1 (first part), and pushes the cylindrical front end portion 400β radially outward along the direction of arrow A1.

[0089] The second tapered portion 920, located on the root side of the forming die 900, abuts against the cylindrical front end portion 400β at the abutment surface B2 (second part), and pushes the cylindrical front end portion 400β radially outward along the direction of arrow A2. As a result, the cylindrical front end portion 400β of the positive end 400 expands in diameter.

[0090] In this way, by pressing different parts (abutting surfaces B1 and B2) of the cylindrical front end 400β along different directions (arrows A1 and A2), the entire cylindrical front end 400β can be deformed. Therefore, it is possible to suppress the excessive local stress of the cylindrical front end 400β during the riveting process, which could lead to fracture.

[0091] In addition, the first tapered portion 910 pushes the root of the cylindrical front end portion 400β, and the cylindrical front end portion 400β expands in diameter from the root. Therefore, the riveting portion 400A can easily expand and easily reach the side wall of the countersink 610A.

[0092] Furthermore, even when the forming die 900 is off-center relative to the positive end 400, the first tapered portion 910 with a relatively small tilt angle relative to the central axis CL can suppress shape deviation while deforming the cylindrical front end 400β.

[0093] Thus, by using the forming mold 900 of this embodiment, the breakage of the cylindrical front end 400β can be suppressed, and the shape of the formed riveting portion 400A can also be stabilized.

[0094] Here, the maximum diameter of the first tapered portion 910 (2×R3: reference) Figure 12 ) 400β aperture of the cylindrical front end (2×R1: reference) Figure 12 Larger. More preferably, the maximum diameter (2×R3) of the first tapered portion 910 is about 50 μm larger than the aperture (2×R1) of the cylindrical front end portion 400β (more preferably about 100 μm larger).

[0095] The relationship (R3 > R1) is valid in at least one cross section passing through the central axis CL, but it is more preferable that the relationship (R3 > R1) is valid in a cross section (e.g., a cross section in the long axis direction) including the portion of the front end of the positive terminal 400 welded to the first positive current collector 610, and even more preferably that the relationship (R3 > R1) is valid in all cross sections (cross sections in the full circumference direction around the central axis CL) including the central axis CL.

[0096] By satisfying the above relationship (R3 > R1), pushing forces in different directions (arrows A1, A2) can be reliably applied from the first tapered portion 910 and the second tapered portion 920 of the forming mold 900 to the cylindrical front end portion 400β of the positive terminal 400. As a result, the shape of the riveting portion 400A can be easily stabilized.

[0097] Figure 15 It means to continue Figure 13 , Figure 14 The diagram of the third process. Figure 16 yes Figure 15 A magnified view of the riveted joint in the image.

[0098] like Figure 15 , Figure 16 As shown, the riveting portion 400A is further pressed by the second mold 900A. As a result, the front end of the cylindrical front end 400β reaches the side wall of the countersunk hole 610A. The front end of the positive terminal 400 is welded to the first positive current collector 610. By reliably ensuring that the front end of the positive terminal 400 reaches the side wall of the countersunk hole 610A, welding is easy, and the weld strength is also stable.

[0099] Figure 17 This diagram shows the first step in forming the riveting part 400A of the comparative example. Figure 18 yes Figure 17 A magnified view of the front end of the mold. Figure 19 It means to continue Figure 17 , Figure 18 The diagram for the second process, Figure 20 yes Figure 19 A magnified view of the front end of the mold. Additionally, Figure 21 It means to continue Figure 19 , Figure 20 The diagram of the third process. Figure 22 yes Figure 21 A magnified view of the riveted joint in the image.

[0100] exist Figures 17-22 In the comparative examples shown, it was also after being compared with... Figures 11-16 The same process is used to form the riveted part 400A. However, in Figures 17-22 In the comparative example, the shape of the forming mold 900 is different from the structure of this embodiment.

[0101] That is, in Figures 17-22 In the comparative example, the curved surface B3 located on the front end side of the forming die 900 does not abut against the cylindrical front end 400β of the positive terminal 400, and the pushing force is concentrated at the front end of the cylindrical front end 400β. As a result, the cylindrical front end 400β may break. Furthermore, the root of the cylindrical front end 400β is not directly pushed, making this part difficult to deform; therefore, the riveting part 400A is difficult to expand. As a result, as... Figure 21 , Figure 22 As shown, sometimes the riveting part 400A does not reach the side wall of the countersunk hole 610A.

[0102] Figure 23 This is a schematic diagram showing the riveting joint of this embodiment and the comparative example. Figure 24 , Figure 25 They represent from Figure 23 A diagram showing the riveting joint of this embodiment and the comparative example is extracted. (Refer to...) Figures 23-25It is easy to understand that in this embodiment, when the forming mold 900 is inserted into the cylindrical front end 400β, the first tapered portion 910 abuts against the cylindrical front end 400β, but in the comparative example, the curved surface B3 does not abut against the cylindrical front end 400β.

[0103] Figure 26 This diagram illustrates the stress distribution along the path leading to the riveted joint 400A. (Refer to...) Figure 26 The stress is greatest in region C2, located at the very front of the cylindrical front end 400β. The stress in region C1, located at the root side of region C2, is less than the stress in region C2. The stress in region C3, located at the bottom of the cylindrical front end 400β, is less than the stress in region C1.

[0104] Thus, the stress generated during the riveting process is greater towards the front end of the cylindrical front end 400β. According to the forming mold 900 of this embodiment, since the root of the cylindrical front end 400β can be pressed by the first tapered portion 910, the stress generated at the foremost end (region C2) of the cylindrical front end 400β can be mitigated, and the breakage of the cylindrical front end 400β can be suppressed.

[0105] Figure 27 This is a graph showing the relationship between the riveting diameter and the maximum equivalent total strain. Here, "riveting diameter" refers to the opening diameter at the front end of the cylindrical front end 400β, which is expanded by the forming die 900. Therefore, the "riveting diameter" increases as the riveting process proceeds.

[0106] like Figure 27 As shown, in the case of using the forming mold 900 of this embodiment (Example), compared with the comparative example, the increase in the maximum value of the equivalent total strain is suppressed overall. As a result, the fracture of the cylindrical front end 400β can be suppressed, and the shape of the formed riveted portion 400A can be stabilized.

[0107] Next, use Figure 28 , Figure 29 The shape of the riveted portion 400A during and after the riveting joint in this embodiment will be described, and... Figure 30 , Figure 31 The shape of the riveted part 400A during and after the riveting joint of the comparative example will also be described.

[0108] In the square secondary battery 1 of this embodiment, as Figure 28 As shown, the first tapered portion 910 and the second tapered portion 920 push the cylindrical front end 400β of the positive terminal 400, thus, during the intermediate process, two bending portions D1 and D2 are generated, causing the inclination of the inner circumferential surface 400α to change discontinuously. Furthermore, as... Figure 29As shown, after being further pressed by the second mold 900A, the bent part D1 on the root side also remains.

[0109] In contrast, in the comparative example, such as Figure 30 As shown, a bending section D3 is formed during the intermediate process, but as... Figure 31 As shown, after being further pressed by the second mold 900A, no bends remain that would cause the inclination of the inner circumferential surface 400α to change discontinuously.

[0110] However, in the square secondary battery 1 of this embodiment, there is also a case where no bending portion D1 remains.

[0111] The bend D1 is sometimes formed as a ring around the entire circumference of the inner circumferential surface 400α, but sometimes it is formed on a portion of the circumferential direction of the inner circumferential surface 400α.

[0112] In the example above, the riveting part 400A inside the battery casing 100 was described, but as... Figure 32 As shown, the same structure can also be used in the riveting portion 400B between the terminal member 401 of the positive terminal 400 and the external terminal 402. That is, the riveting joint structure of the present invention can also be applied to the joint structure of the terminal member and the conductive member disposed on the outside of the battery housing 100.

[0113] Alternatively, a third tapered portion (not shown) may be provided, which is located on the large-diameter side of the second tapered portion 920 and is inclined at a larger angle relative to the central axis CL than the second tapered portion.

[0114] Embodiments of the present invention have been described, but should be considered illustrative rather than restrictive in all respects. The scope of the invention is defined by the claims, including all modifications within the meaning and scope of the claims.

Claims

1. A battery, wherein, have: A conductive component having a through hole; and A terminal component, which is inserted into the through hole, has a front end exposed on the conductive member. The front end of the terminal component is riveted to the conductive component. The front end portion of the terminal component includes a recess having an inner circumferential surface. A bend is formed on the inner circumferential surface, wherein the inclination of the inner circumferential surface relative to the central axis of the terminal member changes. With the front end of the terminal member riveted to the conductive member, the inner circumferential surface adjacent to one side of the bent portion and the inner circumferential surface adjacent to the other side of the bent portion are inclined in a direction that moves away from the central axis as they move away from the bent portion, with the bent portion as the boundary.

2. The battery according to claim 1, wherein, The conductive component includes a hole with sidewalls. The riveted joint is formed within the hole. At the riveted joint, the front end of the terminal member reaches the sidewall of the hole.

3. The battery according to claim 2, wherein, At least a portion of the riveted joint is provided in which the front end of the terminal member is welded to the conductive member.

4. The battery according to any one of claims 1 to 3, wherein, The battery also includes electrode bodies. The conductive component is a current collector that electrically connects the electrode body to the terminal component.

5. A method for manufacturing a battery, wherein, have: The process of inserting terminal components into through holes in conductive components; as well as The process of riveting the front end of the terminal component to the conductive component. The riveting process includes: Prepare a forming mold including a first tapered portion and a second tapered portion, wherein the first tapered portion is inclined at a first angle relative to the central axis of the terminal member, and the second tapered portion is disposed on the large diameter side of the first tapered portion and is inclined at a second angle greater than the first angle relative to the central axis; as well as The first tapered portion of the forming mold is positioned facing the front end of the terminal component. The forming mold is moved along the central axis and inserted into the cylindrical portion formed at the front end of the terminal component. The first tapered portion pushes a first portion of the cylindrical portion radially outward, and the second tapered portion pushes a second portion of the cylindrical portion radially outward, thereby expanding the diameter of the front end of the terminal component. By expanding the diameter of the front end portion of the terminal member, a recess with an inner circumferential surface is formed at the front end portion of the terminal member. A bend is formed on the inner circumferential surface, wherein the inclination of the inner circumferential surface relative to the central axis of the terminal member changes. With the front end of the terminal member riveted to the conductive member, the inner circumferential surface adjacent to one side of the bent portion and the inner circumferential surface adjacent to the other side of the bent portion are inclined in a direction that moves away from the central axis as they move away from the bent portion, with the bent portion as the boundary.

6. The method for manufacturing a battery according to claim 5, wherein, In at least one cross-section passing through the central axis, the maximum diameter of the first tapered portion is larger than the aperture of the cylindrical portion.

7. The method for manufacturing a battery according to claim 6, wherein, In at least one cross-section passing through the central axis, the maximum diameter of the first tapered portion is more than 50 μm larger than the aperture of the cylindrical portion.

8. A method for manufacturing a battery according to any one of claims 5 to 7, wherein, In at least all cross sections passing through the central axis, the minimum diameter of the first tapered portion is more than 100 μm smaller than the aperture of the cylindrical portion.

9. A method for manufacturing a battery according to any one of claims 5 to 7, wherein, It also includes a step of welding the front end of the terminal component, which is joined to the conductive component, to the conductive component.

10. The method for manufacturing a battery according to claim 8, wherein, It also includes a step of welding the front end of the terminal component, which is joined to the conductive component, to the conductive component.

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