Battery, fastening structure body, battery manufacturing method, and method for manufacturing fastening structure body

Abstract

A battery according to the present disclosure comprises an electrode body (1), a current collector 15 connected to the electrode body (1), and an external terminal 11 formed on and connected to the current collector 15. The current collector 15 includes a body part and a current collector plate part connected to the body part. The body part has a through-hole. A rib 21 is formed around the through-hole of the body part. The external terminal 11 includes: a current collector connection part 11b inserted into the through-hole of the body part; and an enlarged-diameter part 11c that is continuous with the current collector connection part 11b along the lamination direction and has a larger dimension in a direction intersecting the lamination direction than the current collector connection part 11b. A recessed part 23 is formed at an end part of the enlarged-diameter part 11c facing the electrode body (1) along the lamination direction. The enlarged-diameter part 11c has a contact part with the rib 21 in a direction intersecting the lamination direction. In a cross-section passing through the enlarged-diameter part 11c and the contact part, the enlarged-diameter part 11c or the enlarged-diameter part 11c and current collector connection part 11b have a first fixing part to which the current collector 15 is fixed in a direction intersecting the lamination direction, and a second fixing part to which the current collector 15 is fixed in the lamination direction. The first fixing part has a wider structure than the second fixing part. This suppresses deformation of a component to be fastened when a fastening structure body is manufactured, and enables provision of a battery and a fastening structure body that have a high-quality fastening structure.

Description

Battery, fastening structure, battery manufacturing method, and fastening structure manufacturing method

[0001] The present disclosure relates to a battery, a fastening structure, a method for manufacturing a battery, and a method for manufacturing a fastening structure.

[0002] Conventionally, battery electrode terminals are fabricated by pressing the terminal of the lid assembly in the axial direction of the terminal with a crimping tool or the like to tightly contact the laminated current collector or other plate material.

[0003] Patent Document 1 discloses a method for manufacturing a secondary battery in which, when crimping the internal terminal 6, a crimping tool 20 is used to press the protruding portion 6a of the internal terminal 6 from the protruding direction, deforming it so that it expands radially, and further deforming the protruding portion 6a of the internal terminal 6 to form a crimping portion 21, thereby fixing the internal terminal 6 to the through hole 4a of the external terminal 4.

[0004] JP 2015-106501 A

[0005] In the method described in Patent Document 1, the step of forming the crimped portion 21 involves pressing the upper portion of the protruding portion 6a that expands in the radial direction of the internal terminal 6 to bring the internal terminal 6 into close contact with the external terminal 4 in the pressing direction. In this case, it is desirable to prevent the stacked case 2 and the like from being pressed and deforming the case 2.

[0006] Even when the case itself is not pressed, it is desirable to sandwich the lid as the fastened part and prevent the lid from being deformed.

[0007] An object of the present disclosure is to provide a battery and a fastening structure that have a high-quality fastening structure by suppressing deformation of fastened parts when manufacturing the fastening structure.

[0008] The battery of the present disclosure includes an electrode assembly, a current collector connected to the electrode assembly, and an external terminal stacked on and connected to the current collector. The current collector includes a main body portion and a current collector plate portion connected to the main body portion. The main body portion has a through hole. A rib is formed around the through hole in the main body. The external terminal includes a current collector connection portion inserted into the through hole in the main body portion and an expanded diameter portion connected to the current collector connection portion along the stacking direction and having a dimension larger than that of the current collector connection portion in a direction intersecting the stacking direction. A recess is formed at an end of the expanded diameter portion facing the electrode assembly along the stacking direction. The expanded diameter portion has a contact portion with the rib in a direction intersecting the stacking direction. In a cross section passing through the expanded diameter portion and the contact portion, the expanded diameter portion, or the expanded diameter portion and current collector connection portion, has a first fixing portion to which the current collector is fixed in a direction intersecting the stacking direction and a second fixing portion to which the current collector is fixed in the stacking direction. The first fixing portion has a wider structure than the second fixing portion.

[0009] According to the present disclosure, it is possible to provide a battery and a fastening structure with a high-quality fastening structure by suppressing deformation of fastened parts when manufacturing the fastening structure.

[0010] 1 is a perspective view showing a battery with the lid portion disassembled; FIG. 2 is a cross-sectional view showing the fastening structure of Example 1; FIG. 3 is a cross-sectional view showing the fastening structure of Example 2; FIG. 4 is a cross-sectional view showing a state before the connection portion is crimped in the process of producing the fastening structure of Example 1; FIG. 5 is a cross-sectional view showing the fastening structure of Example 3; FIG. 6 is a cross-sectional view showing the fastening structure of Example 4; FIG. 7 is a partially enlarged cross-sectional view showing the fastening structure of Modified Example 1; FIG. 8 is a partially enlarged cross-sectional view showing the fastening structure of Modified Example 2; FIG. 9 is a partially enlarged cross-sectional view showing the fastening structure of Modified Example 3; FIG. 10 is a partially enlarged cross-sectional view showing the fastening structure of Modified Example 1; Fig. 2 is a partially enlarged cross-sectional view showing the fastening structure of Modified Example 16. Fig. 3 is a partially enlarged cross-sectional view showing the fastening structure of Modified Example 17. Fig. 4 is a partially enlarged cross-sectional view showing the fastening structure of Modified Example 18. Fig. 5 is a cross-sectional view showing the state immediately before the crimping step of the fastening structure (part of the lid assembly) of Example 5. Fig. 6 is a cross-sectional view showing the completed state of the fastening structure (part of the lid assembly) of Example 5.

[0011] FIG. 1 is a perspective view showing a battery with the lid disassembled.

[0012] The battery 100 shown in this figure includes an electrode group 1 (electrode body), a case 2 that houses the electrode group 1, and a lid assembly 5. The case 2 and lid assembly 5 are collectively referred to as the "exterior body." The lid assembly 5 includes a positive electrode terminal 3 and a negative electrode terminal 4. The lid assembly 5 includes an external terminal 11, a gasket 12, a lid 13, an insulating block 14, and a current collector 15. The gasket 12, the lid 13, the insulating block 14, and the current collector 15 are stacked in this order, and the external terminal 11 is inserted with the through holes of each of these elements aligned. The current collector 15 includes a main body portion (upper portion in the figure) and a current collector plate portion (lower portion in the figure) connected to the underside of the main body portion. The main body portion has a through hole. The current collector plate portion is configured to be electrically connected to the electrode group 1.

[0013] The completed lid assembly 5 has a structure (fastening structure) in which the inserted external terminals 11 are fastened by crimping. The direction along the largest main surface of the case 2 and passing through the external terminals 11 is defined as the X direction. The direction perpendicular to the X direction, along the surface adjacent to the main surface, in which the batteries are stacked is defined as the Y direction. The direction perpendicular to the X direction and the Y direction is defined as the Z direction.

[0014] Generally, an assembly of components, etc., which is produced by stacking a plurality of fastened parts (plate-like members, etc.) having through holes, aligning the through holes of these fastened parts, inserting a columnar member, which is a fastening member, and crimping the columnar member, has a fastening structure.

[0015] A fastening structure according to an embodiment of the present disclosure will be described below with reference to the drawings. Note that, although the following embodiment will be described using a battery lid assembly as an example, the fastening structure according to the present disclosure can also be applied to assemblies other than batteries. Furthermore, the fastening structure according to the present disclosure can be applied regardless of the type of battery. Examples of batteries include secondary batteries using a liquid electrolyte, secondary batteries containing a solid electrolyte, and all-solid-state batteries.

[0016] Fig. 2 is a cross-sectional view showing the fastening structure (part of the lid assembly) of Example 1. That is, it is a cross-section (X-Z direction cross-section) showing the state in which external terminals 11 are inserted into and crimped into the through-holes of some of the components in Fig. 1. In Fig. 2, the positive and negative directions of the Z direction (up and down directions) are opposite to those in Fig. 1.

[0017] The fastening structure shown in Figure 2 is part of a battery lid assembly, and is made up of, from bottom to top, a gasket 12, a lid 13, an insulating block 14, and a current collector 15. The current collector connection portion 11b of the external terminal 11 (columnar member) is inserted into the through-holes. An enlarged diameter portion 11c is formed at the top of the external terminal 11. The bus bar connection portion 11a of the external terminal 11 is in contact with the gasket 12. A rib 21 is formed around the through-hole of the current collector 15. The external terminal 11 and the current collector 15 are made of metal. The lid 13 may also be made of metal.

[0018] The upper surface of the enlarged diameter portion 11 c of the external terminal 11 is at approximately the same height as the upper end of the rib 21 .

[0019] The gasket 12 is disposed between the bus bar connection portion 11a of the external terminal 11 and the lid 13. The gasket 12 has a sheath portion. The sheath portion is disposed between the inner wall 13n of the through hole in the lid 13 of the external terminal 11 and the outer periphery of the current collector connection portion 11b. In this figure, the sheath portion reaches the center in the thickness direction of the insulating block 14. In other words, the gasket 12 is disposed along the inner wall 13n of the through hole, connected to the insulating block 14, and in contact with the current collector connection portion 11b. The overall thickness of the portion where the gasket 12, lid 13, and insulating block 14 are stacked is indicated by the reference symbol 12a. The thickness 12a is longer than the length of the sheath portion.

[0020] The sheath portion is disposed between the inner wall of the through hole of the lid 13 and the collector connection portion 11b (columnar portion) of the external terminal 11. The diameter of the expanded diameter portion 11c of the external terminal 11 is preferably smaller than the diameter of the through hole of the lid 13.

[0021] Regarding the diameter of the collector connection portion 11b, diameter 11b1 indicates the dimension of the bottom of the through hole of the collector 15, diameter 11b2 indicates the dimension of the top of the through hole of the collector 15, diameter 11b3 indicates the dimension of the bottom of the through hole of the gasket 12, and diameter 11b4 indicates the dimension of the narrow part of the through hole of the insulating block 14.

[0022] The current collector connection portion 11b of the external terminal 11 faces an inner wall 13n of the through hole of the lid 13 via the gasket 12. The current collector connection portion 11b also faces an inner wall 14n of the through hole of the insulating block 14 (insulating member). The current collector connection portion 11b is in intimate contact with the inner wall 15n of the through hole of the current collector 15 by crimping.

[0023] The width of the portion of the external terminal 11 facing the inner wall 15n of the through hole of the collector 15 is shown as A1, the width of the portion of the external terminal 11 facing the inner wall 14n of the through hole of the insulating block 14 is shown as B1, and the diameter of the portion of the external terminal 11 facing the inner wall 13n of the through hole of the lid 13 is shown as D1.

[0024] The inside of the rib 21 is provided with a portion (enlarged diameter portion support portion 15s) that is the same height as the outer main surface of the current collector 15. The enlarged diameter portion 11c of the external terminal 11 is a portion that has been enlarged and crimped by a crimping punch 22. A recess 23 is formed in the enlarged diameter portion 11c by the crimping punch 22. The current collector 15 is connected to the positive electrode or the negative electrode of the electrode group.

[0025] The tip of the crimping punch 22 is conical in shape, and the recess 23 is formed by pressing the tip of the crimping punch 22, resulting in a conical recess. The recess 23 of the enlarged diameter portion 11c corresponds to the conical shape of the tip of the crimping punch 22, so the tip of the crimping punch 22 does not come into contact with, for example, any part of the enlarged diameter portion 11c other than the recess 23. Therefore, no trace of friction caused by the crimping punch 22 remains in any part of the tip of the enlarged diameter portion 11c other than the recess 23. Therefore, even if wrinkles or the like occur when the recess 23 is formed, no trace of friction remains in any part of the tip of the enlarged diameter portion 11c other than the recess 23. Therefore, the part of the tip of the enlarged diameter portion 11c other than the recess 23 can be called an "uncontacted surface."

[0026] The enlarged diameter portion 11c is pressed against the enlarged diameter portion support portion 15s inside the rib 21 and is in intimate contact with the inner wall of the rib 21, and at least a portion of the enlarged diameter portion 11c is pressed against and fixed to the inner wall of the rib 21 by the enlarged diameter portion 11c. Arrows [A], [B], and [C] in the figure represent the action and reaction of the force caused by the pressing. Arrow [A] represents the action and reaction between the current collector connection portion 11b and the inner wall 15n of the through hole of the current collector 15. Arrow [B] represents the action and reaction between the enlarged diameter portion 11c and the enlarged diameter portion support portion 15s. Arrow [C] represents the action and reaction between the enlarged diameter portion 11c and the inner wall 21n of the rib 21. Thus, between the external terminal 11 and the current collector 15, not only a force in the axial direction (Z direction) of the through hole but also a force in the radial direction (X direction) of the through hole acts. Furthermore, a force in the radial direction (X direction) of the through hole acts between the enlarged diameter portion 11c of the external terminal 11 and the rib 21. This ensures that the external terminal 11 and the current collector 15 are sufficiently fixed together, and electrical connection is achieved.

[0027] For example, when viewed in a cross section (Z-X plane) passing through the external terminal 11, the external terminal 11 has a first fixing portion that is tightly fixed to the current collector 15 by the forces indicated by arrows [A] and [C] in the direction (X direction) along the surface of the case 2 (battery container) in FIG. 1 , and a second fixing portion that is tightly fixed to the current collector 15 by the force indicated by arrow [B] in the stacking direction (Z direction) of the lid 13 and the current collector 15. The first fixing portion is wider than the second fixing portion. Specifically, the first fixing portion corresponding to arrow [A] includes the fixing portion between the current collector 15 and the current collector connection portion 11b. The first fixing portion corresponding to arrow [C] includes the fixing portion between the rib 21 of the current collector 15 and the expanded diameter portion 11c. The second fixing portion corresponding to arrow [B] includes the fixing portion (Z direction) between the expanded diameter portion 11c and the current collector 15. For example, these fixing portions (first fixing portion and second fixing portion) are in close contact with each other by caulking.

[0028] This makes it possible to provide a battery having a fastening structure that is highly reliable by suppressing deformation of the fastening structure (in this embodiment, the battery lid 13).

[0029] Specifically, for example, the external terminal 11 has a fixed portion that is caulked to the current collector 15, and the sum of the portions that are in close contact (fixed) in the radial direction (X direction) (the portion of the current collector connecting portion 11b that constitutes the first fixed portion and the portion of the expanded diameter portion 11c that constitutes the first fixed portion) is wider than the portion that is in close contact (fixed) in the axial direction (Z direction) that constitutes the second fixed portion. When viewed in cross section, this is long.

[0030] The width A1 of the portion constituting the first fixing portion corresponds to the portion facing the inner wall 15n of the current collector 15. The width C1 of the portion constituting the first fixing portion corresponds to the portion facing the inner wall 21n of the current collector 15 (e.g., rib 21). The width B1 of the portion constituting the second fixing portion corresponds to the portion facing the enlarged diameter portion support portion 15s of the current collector 15. It is desirable that the sum of the width A1 and the width C1 is greater than the width B1.

[0031] With this configuration, when the expanded diameter portion 11c is formed by plastic deformation caused by crimping, the stress acting in the stacking direction on the current collector 15 and the external terminal 11 can be reduced, thereby suppressing deformation of the current collector 15 and the external terminal 11 in the stacking direction.

[0032] It is preferable that the adhesive force constituting the first fixing portion in the radial direction (X direction) is small (it may be zero).

[0033] If the first and second fixing portions are not formed around the entire circumference of the external terminal 11, it is possible to measure the above lengths in cross sections in the X and Y directions (FIG. 1) and compare the totals. Alternatively, the comparison may be made using the area of ​​the contact portion between the first and second fixing portions of the external terminal 11. For example, the contact area in the X and Y directions is formed to be larger than the contact area in the Z direction.

[0034] In this specification, the inner walls of the ribs 21 are included in the inner walls of the through holes of the current collector 15 .

[0035] Furthermore, as shown in the figure, it is preferable that the enlarged diameter portion 11c and the rib 21 are joined by laser welding (LBW) or the like to form a welded portion 24. This makes it possible to further securely fix and electrically connect the external terminal 11 and the current collector 15.

[0036] From the viewpoint of fixation and electrical connection, it is desirable for the rib 21 to surround the entire periphery of the through hole, but it may also be configured to surround only a portion of the periphery of the through hole.

[0037] In the Z direction, the expanded diameter portion 11c of the external terminal 11 is mainly formed outside the ribs 21 of the surrounding current collector 15, and is disposed farther from the lid 13 than the surface of the current collector 15 formed along the X direction. For example, the portion of the expanded diameter portion 11c farther from the lid 13 than the surface of the current collector 15 is larger (longer) than the portion closer to the lid 13 than the surface of the current collector 15. The portion (rib 21) facing the expanded diameter portion 11c can be easily formed.

[0038] Specifically, for example, in the stacking direction (Z direction) of the lid 13 and the current collector 15, the end of the recess 23 of the enlarged diameter portion 11c on the lid 13 side, which is on the bus bar connection portion 11a side, is positioned on the side farther away from the lid 13 than the surface of the current collector 15. This makes it easy to form the enlarged diameter portion 11c.

[0039] Furthermore, the diameter 11c1 (in the X direction) of the expanded diameter portion 11c is smaller than the diameter D1 of the inner wall 13n of the through hole in the lid 13. The inner wall 13n of the through hole in the lid 13 faces the insulating member (gasket 12). This reduces the effect of pressure applied for adhesion in the Z direction on the lid 13, the insulating block 14, or the current collector 15.

[0040] Furthermore, the diameter 11c1 (in the X direction) of the expanded diameter portion 11c is larger than the diameter D1 of the inner wall 13n of the through hole of the lid 13. The inner wall 13n of the through hole of the lid 13 faces the insulating member (gasket 12). This allows the pressure for tight contact in the Z direction to be controlled with high precision.

[0041] FIG. 4 is a cross-sectional view showing the state before the connecting portion is crimped in the process of producing the fastening structure of this embodiment.

[0042] In this figure, the gasket 12, lid 13, insulating block 14, and collector 15 are stacked in this order, and the collector connection portion 11b of the external terminal 11 is inserted into the through hole with the through holes of each of these overlapping.

[0043] In this state, the diameter of the current collector connection portion 11b is expanded by pressing the tip of the current collector connection portion 11b with the crimping punch 22 shown in Fig. 2. The pressing by the crimping punch 22 is performed by causing the crimping punch 22 to collide with the tip of the current collector connection portion 11b (Fig. 4) at a predetermined speed once or twice or more times.

[0044] Because the tip of the crimping punch 22 is conical, the tip of the current collector connection portion 11b is subjected to not only an axial force but also a radial force of the current collector connection portion 11b. As a result, a recess 23 is formed, the radius of the tip of the current collector connection portion 11b increases, and the outer periphery of the current collector connection portion 11b comes into contact with the inner wall of the rib 21. Then, action and reaction of forces represented by arrows [A], [B], and [C] occur, and the external terminal 11 is crimped.

[0045] 4, the height of the tip of the current collector connection portion 11b is slightly higher than the height of the rib 21. This is because the deformation of the tip of the current collector connection portion 11b as described above makes the height of the tip of the current collector connection portion 11b after crimping approximately equal to the height of the rib 21.

[0046] When the inner diameter of the rib 21 is slightly larger than the radius of the tip of the current collector connection portion 11b, the height of the tip of the current collector connection portion 11b after crimping remains almost the same as before crimping, and the crimped state is sufficient even if the radius of the recess 23 is small. In this case, the area of ​​the non-contact surface described above becomes large.

[0047] In this embodiment, the tip of the crimping punch 22 is shown to have a conical shape, but the shape of the tip of the crimping punch 22 is not limited to this and may be a pyramidal shape with a polygonal horizontal cross section, such as a triangular pyramid or a square pyramid. It may also be a shape without a sharp point, such as a spherical or hemispherical shape. Furthermore, the tip of the crimping punch 22 may be a cylindrical shape with a radius smaller than the radius of the enlarged diameter portion 11c, or may be a cylindrical shape with a polygonal horizontal cross section, such as a triangular prism or a square prism.

[0048] The recess 23 is subjected to pressing by the crimping punch 22, leaving traces of deformation, friction, sliding, etc. of the metal structure toward the center of the recess 23. In this specification, these traces are referred to as "pressing traces." Microscopically, the pressing traces are a special state in which the metal structure (metal crystals, etc.) has moved toward the center of the recess 23. These traces can be observed using a microscope or the like. The pressing traces are observed as metal structure that spreads radially from the center of the recess 23. This radially spreading metal structure is generated because the pressing by the crimping punch 22 is performed without rotating the crimping punch 22.

[0049] If the tip of the crimping punch 22 is columnar, traces of deformation of the metal structure, friction, sliding, etc. will be observed in the recess 23 where the portion that has come into contact with the periphery of the tip of the crimping punch 22 moves toward the bottom of the recess 23. Such traces will also be referred to as "pressing traces" in this specification.

[0050] FIG. 3 is a cross-sectional view showing a fastening structure according to a second embodiment.

[0051] In this figure, no rib is provided on the current collector 35, but a countersunk portion 36 having an opening with a diameter larger than that of the through hole is provided around the periphery of the through hole, and a groove 37 is provided to surround the countersunk portion 36. The bottom of the countersunk portion 36 is formed from one surface to just before reaching the opposite main surface. After an enlarged diameter portion 11c is formed using a caulking punch 22, a weld 38 is formed using LBW or the like. The portion of the current collector 35 remaining between the countersunk portion 36 and the groove 37 functions similarly to a rib with respect to the enlarged diameter portion 11c. It is desirable to provide the groove 37 so as to surround the entire periphery of the countersunk portion 36, but it may also be provided only on a portion of the periphery of the countersunk portion 36.

[0052] In the Z direction, most of the expanded diameter portion 11c (FIG. 2) of the external terminal 11 is formed outside the groove 37 of the surrounding current collector 35, and is located closer to the lid 13 than the surface of the current collector 35 formed along the X direction. For example, the portion of the expanded diameter portion 11c that is closer to the lid 13 than the surface of the current collector 35 is larger (longer) than the portion that is farther from the surface than the lid 13. This reduces unevenness, allowing for the construction of a battery 100 that is smaller in size and higher in density.

[0053] Specifically, for example, the end of the recess 23 ( FIG. 2 ) of the expanded diameter portion 11c on the busbar connection portion 11a side is located closer to the lid 13 than the surface of the current collector 15. This makes it easy to form a tight contact structure between the outer periphery of the current collector connection portion 11b and the region of the inner wall 15n of the through hole of the current collector 15 on the lid 13 side.

[0054] In this specification, the inner wall of the counterbore 36 is included in the inner wall of the through hole of the current collector 15 .

[0055] According to this embodiment, since the current collector 35 is not provided with ribs, the main surfaces of the current collector 35 are free of protrusions, that is, the main surfaces can be made relatively flat.

[0056] Furthermore, the counterbore 36 and the groove 37 can be formed simply by cutting the current collector 35, which is advantageous in that the current collector 35 can be easily processed.

[0057] FIG. 5 is a cross-sectional view showing a fastening structure according to a third embodiment.

[0058] In this figure, a groove 27 is added to the outer periphery of the rib 21 compared to the configuration in Figure 2. By providing the groove 27, the rib 21 can be more easily deformed radially outward when forming the expanded diameter portion 11c, and the area of ​​contact between the expanded diameter portion 11c and the rib 21 and the current collector 15 can be increased.

[0059] FIG. 6 is a cross-sectional view showing a fastening structure according to a fourth embodiment.

[0060] In this figure, the groove 37 is not provided, unlike the configuration in Figure 3. Even in this case, the expanded diameter portion 11c is in close contact with the inner wall of the countersunk portion 36, so that the external terminal 11 is fixed and electrically connected.

[0061] According to this embodiment, the main surfaces of the current collector 35 can be made even flatter than in the second embodiment, and cutting of the current collector 35 becomes even easier.

[0062] In the above examples, the fastening structure of a battery lid assembly is used as an example for explanation, but the fastening structure of the present disclosure is not limited to battery lid assemblies and can be applied to assemblies made by fastening multiple parts together by crimping.

[0063] Next, a modified example of the enlarged diameter portion 11c of the external terminal 11 shown in FIG. 2 will be described with reference to the drawings.

[0064] (Modification) FIG. 7 is a partially enlarged cross-sectional view showing a fastening structure according to a first modification.

[0065] In this figure, the lid 13, insulating block 54, and current collector 55 are stacked in this order, and the external terminal 11 is inserted with the through holes of each of these overlapping. The current collector 55 has a rib 51. The current collector connection portion 11b of the external terminal 11 (columnar member) is inserted into the overlapping through hole. The enlarged diameter portion 11c of the external terminal 11 is in close contact with the rib 51 of the current collector 55. A recess 23 is formed on the upper surface of the enlarged diameter portion 11c using a crimping punch. A weld 24 is formed between the enlarged diameter portion 11c and the rib 51.

[0066] The upper surfaces of the enlarged diameter portion 11c, the rib 51, and the welded portion 24 are generally flat, except for the recessed portion 23. Furthermore, neither the inner nor outer wall surface of the rib 51 is inclined relative to the Z-axis direction. In other words, the inclination in the Z-axis direction is 0 degrees. In further words, the radius of the upper and lower parts of the inner and outer wall surfaces of the rib 51 are equal. However, the radius of part or all of the upper part of the inner wall surface of the rib 51 is larger because the welded portion 24 is formed thereon.

[0067] Regarding the following modifications, only the differences from the first modification will be described.

[0068] FIG. 8 is a partially enlarged cross-sectional view showing the fastening structure of the second modification.

[0069] In this figure, the inner wall surface of the rib 51 is not inclined with respect to the Z-axis direction. On the other hand, the outer wall surface of the rib 51 is inclined with respect to the Z-axis direction. Specifically, when comparing the radius of the upper part of the outer wall surface of the rib 51 with the radius of the lower part, the radius of the upper part is smaller. In other words, the rib 51 is formed so as to widen from the upper part of the outer periphery toward the lower part. In further words, in a cross section along the XZ plane, the angle formed by the slope of the outer periphery of the rib 51 and a line parallel to the Z-axis is positive.

[0070] Such a configuration of the rib 51 can increase the rigidity of the rib 51. This can suppress deformation of the rib 51 due to the force that is applied to the rib 51 when the external terminal 11 is plastically deformed to form the enlarged diameter portion 11c.

[0071] FIG. 9 is a partially enlarged cross-sectional view showing the fastening structure of the third modified example.

[0072] In this figure, the inner wall surface of the rib 51 is inclined in the Z-axis direction. On the other hand, the outer wall surface of the rib 51 is not inclined in the Z-axis direction. Specifically, when comparing the radius of the upper part of the inner wall surface of the rib 51 with the radius of the lower part, the radius of the upper part is larger. In other words, the rib 51 is formed so as to narrow from the upper part to the lower part of the inner periphery. In further words, in a cross section along the XZ plane, the angle formed by the slope of the inner periphery of the rib 51 and a line parallel to the Z-axis is positive.

[0073] Such a configuration of the rib 51 increases the rigidity of the rib 51. This suppresses deformation of the rib 51 due to the force applied to the rib 51 when the external terminal 11 undergoes plastic deformation to form the enlarged diameter portion 11c. This also has the effect of making it easier to bring the enlarged diameter portion 11c and the inner peripheral portion of the rib 51 into close contact with each other.

[0074] FIG. 10 is a partially enlarged cross-sectional view showing the fastening structure of the fourth modification.

[0075] In this figure, both the inner and outer wall surfaces of the rib 51 are inclined with respect to the Z-axis direction. Specifically, when comparing the radius of the upper and lower parts of the inner wall surface of the rib 51, the radius of the upper part is larger. On the other hand, when comparing the radius of the upper and lower parts of the outer wall surface of the rib 51, the radius of the upper part is smaller.

[0076] 8 to 10 can be formed by press working, etc. Therefore, the ribs 51 can be formed very easily.

[0077] FIG. 11 is a partially enlarged cross-sectional view showing the fastening structure of the fifth modified example.

[0078] The difference between this figure and the first modified example (FIG. 7) is that a groove 57 is provided around the rib 51. In this case, the material for forming the rib 51 can be obtained from the groove 57.

[0079] With this configuration, when the rib 51 is formed by press working, it is possible to suppress sagging of the shape of the rib 51 of the current collector due to deterioration of the mold used in the press working. In addition, when the enlarged diameter portion 11c is plastically deformed and comes into contact with the rib 51, the rib 51 is plastically deformed toward the groove 57, and the enlarged diameter portion 11c and the rib 21 are easily brought into close contact with each other.

[0080] FIG. 12 is a partially enlarged cross-sectional view showing the fastening structure of the sixth modification.

[0081] As shown in this figure, this modification has a configuration in which a groove 57 is added to the configuration of modification 2 (FIG. 8).

[0082] FIG. 13 is a partially enlarged cross-sectional view showing the fastening structure of the seventh modification.

[0083] As shown in this figure, this modification has a configuration in which a groove 57 is added to the configuration of modification 3 (FIG. 9).

[0084] FIG. 14 is a partially enlarged cross-sectional view showing the fastening structure of the eighth modified example.

[0085] As shown in this figure, this modification has a configuration in which a groove 57 is added to the fourth modification (FIG. 10).

[0086] FIG. 15 is a partially enlarged cross-sectional view showing the fastening structure of the ninth modification.

[0087] In this figure, the rib 51 is extruded outward and plastically deformed, as compared with the fifth modification (FIG. 11). Therefore, the radius of the upper part of both the inner and outer wall surfaces of the rib 51 is larger than the radius of the lower part.

[0088] FIG. 16 is a partially enlarged cross-sectional view showing the fastening structure of the tenth modification.

[0089] This figure shows the expanded diameter portion 11c of the external terminal 11 that has been expanded and crimped by a crimping punch. The radius of the recess 23 formed in the expanded diameter portion 11c is smaller than the radius of the expanded diameter portion 11c.

[0090] FIG. 17 is a partially enlarged cross-sectional view showing the fastening structure of the eleventh modification.

[0091] In this figure, the recess 23 formed in the enlarged diameter portion 11c has a radius equal to the radius of the enlarged diameter portion 11c because the radius is enlarged by a caulking punch with a large taper radius. In this case, there is no uncontacted surface on the upper surface of the enlarged diameter portion 11c.

[0092] FIG. 18 is a partially enlarged cross-sectional view showing the fastening structure of the twelfth modification.

[0093] In this figure, a raised portion is formed around the recess 23 formed in the enlarged diameter portion 11c by being pushed out by a caulking punch.

[0094] The following modified example does not have a rib.

[0095] FIG. 19 is a partially enlarged cross-sectional view showing the fastening structure of the thirteenth modification.

[0096] In this figure, the upper surfaces of the enlarged diameter portion 11c, current collector 55, and welded portion 24 of the external terminal 11 are substantially flat, except for the recess 23. The outer wall surface of the enlarged diameter portion 11c does not have an inclination with respect to the Z-axis direction. In other words, the inclination in the Z-axis direction is 0 degrees. In other words, the radius of the upper and lower parts of the outer wall surface of the enlarged diameter portion 11c are equal. However, the radius of part or all of the upper part of the outer wall surface of the enlarged diameter portion 11c is smaller because the welded portion 24 is formed thereon.

[0097] Corresponding to this configuration, the inner wall surface of the current collector 55 also has no inclination with respect to the Z-axis direction.

[0098] FIG. 20 is a partially enlarged cross-sectional view showing the fastening structure of the fourteenth modification.

[0099] In this figure, the outer wall surface of the expanded diameter portion 11c is inclined with respect to the Z-axis direction. In other words, the outer wall surface of the expanded diameter portion 11c has a larger radius at the top than at the bottom.

[0100] Corresponding to this configuration, the inner wall surface of the current collector 55 also has an inclination with respect to the Z-axis direction.

[0101] FIG. 21 is a partially enlarged cross-sectional view showing the fastening structure of the fifteenth modification.

[0102] As shown in this figure, this modification has a configuration in which a groove 57 is added to the modification 13 (FIG. 19).

[0103] FIG. 22 is a partially enlarged cross-sectional view showing the fastening structure of the sixteenth modification.

[0104] As shown in this figure, this modification has a configuration in which a groove 57 is added to the fourteenth modification (FIG. 20).

[0105] FIG. 23 is a partially enlarged cross-sectional view showing the fastening structure of the seventeenth modification.

[0106] In this figure, unlike Modification 15 (FIG. 21), the inner wall surface of groove 57 is inclined with respect to the Z-axis direction. In other words, the inner wall surface of groove 57 has a smaller radius at the top than at the bottom.

[0107] FIG. 24 is a partially enlarged cross-sectional view showing the fastening structure of Modified Example 18.

[0108] In this figure, unlike Modification 16 (FIG. 22), the inner wall surface of groove 57 is inclined with respect to the Z-axis direction. In other words, the inner wall surface of groove 57 has a smaller radius at the top than at the bottom.

[0109] 25 is a cross-sectional view showing the state immediately before the crimping process of the fastening structure (part of the lid assembly) of Example 5. That is, it is a cross-section (X-Z direction cross-section) showing the state in which the external terminals 11 are inserted into the through-holes of some of the components in FIG.

[0110] The fastening structure shown in this figure is part of a battery lid assembly, and is composed of, from top to bottom, an external terminal 111, a gasket 112, a lid 113, and an insulating block 114 stacked together, with a current collector 115 (columnar member) inserted into the through-holes. The expanded diameter portion 115c of the current collector 115 is expanded and crimped by a crimping punch 122. A recess 123 is formed in the expanded diameter portion 115c by the crimping punch 122. The current collector 115 is connected to the positive or negative electrode of the electrode group. The side wall surface 115n of the current collector 115 is in close contact with the inner wall surface of the external terminal 111 and is electrically connected thereto.

[0111] The gasket 112 is disposed between the external terminal 111 and the lid 113, and is disposed between the side wall surface 115n of the current collector 115 and the inner wall 113n of the through-hole of the lid 113. The gasket 112 is also disposed along the inner wall 113n of the through-hole and is connected to the insulating block 114. In other words, the gasket 112 has a sheath portion.

[0112] That is, in this figure, a through hole is also provided in the external terminal 111, and the columnar portion of the current collector 115 is inserted into this through hole. Then, the tip of the columnar portion of the current collector 115 is expanded in diameter by a crimping punch 122 and crimped.

[0113] FIG. 26 is a cross-sectional view showing the completed state of the fastening structure (part of the lid assembly) of this embodiment.

[0114] In this figure, a recess 123 is formed in the enlarged diameter portion 115c of the current collector 115, and a welded portion 124 is provided. The upper surface of the external terminal 111, the upper surface of the enlarged diameter portion 115c of the current collector 115, and the upper surface of the welded portion 124 are generally flat except for the recess 123. The tip of the enlarged diameter portion 115c has the recess 123 and an uncontacted surface.

[0115] The external terminal 111 has a countersunk portion. The enlarged diameter portion 115c of the current collector 115 is in close contact with the inner wall of the countersunk portion. The height of the uncontacted surface at the tip of the enlarged diameter portion 115c is approximately equal to the height of the upper end of the external terminal 111.

[0116] The current collector 115 includes a current collector plate connection portion 115a, a columnar portion 115b, and an enlarged diameter portion 115c.

[0117] The width of the portion (side wall surface 115n) where the columnar portion 115b presses the external terminal 111 in the X-axis direction is shown as A1, the width of the portion 115s where the expanded diameter portion 115c presses the external terminal 111 in the Z-axis direction is shown as B1, and the width of the portion where the expanded diameter portion 115c presses the external terminal 111 in the Z-axis direction is shown as C1.

[0118] In addition, the diameter of the columnar portion 115b at the portion where the columnar portion 115b contacts the lower part of the external terminal 111 is indicated as 115b1, the diameter of the columnar portion 115b at the portion where the columnar portion 115b contacts the upper part of the external terminal 111 is indicated as 115b2, the diameter of the columnar portion 115b at the portion where the columnar portion 115b contacts the insulating block 114 is indicated as 115b3, the diameter of the columnar portion 115b at the portion where the columnar portion 115b contacts the gasket 112 is indicated as 115b4, the diameter of the expanded diameter portion 115c is indicated as 115c1, and the inner diameter of the through hole in the lid 113 is indicated as D1.

[0119] In summary, the recess 123 and the welded portion 124 in this embodiment are exposed to the outside together with the external terminal 111 .

[0120] Here, a method for manufacturing a fastening structure according to the present disclosure will be described.

[0121] (1) A plurality of fastened components having through holes are stacked, and the through holes are aligned and a columnar member is inserted into the through holes. In this case, a rib or a counterbore is formed in a component constituting the outermost surface of one of the stacked fastened components.

[0122] (2) Next, the tip of the inserted columnar member is pressed with a crimping punch to expand the diameter of the columnar member. Since the columnar member is to be expanded in diameter, it is desirable that the columnar member be solid. It is desirable to leave an uncontacted surface at the tip of the expanded diameter portion. This allows the outer periphery of the expanded diameter portion of the columnar member to tightly contact the inner wall of the rib or counterbore.

[0123] (3) Thereafter, if necessary, the adhered portions are joined using LBW or the like. When using LBW, it is desirable that the height of the adhered portion of the columnar member and the height of the top of the rib or countersunk portion are approximately equal. This is because the laser can be irradiated from above without the need to adjust the position or angle of the laser generator. In this case, "approximately equal height" means that the difference in height is 3 mm or less. It is desirable that the difference in height is 2 mm or less, and more desirably 1 mm or less.

[0124] According to the above manufacturing method, it is possible to reduce the number of times and the time for pressing with the crimping punch, and yet obtain a fastening structure with a tightly bonded joint. In addition, it is no longer necessary to apply excessive force near the joint, and deformation of the joint can be suppressed.

[0125] Furthermore, when the expanded diameter portion is formed by plastic deformation caused by crimping, the stress applied to the current collector and the external terminal in the stacking direction can be reduced, thereby suppressing deformation of the current collector and the external terminal in the stacking direction.

[0126] The above-described method for manufacturing a fastening structure can also be applied to a method for manufacturing a battery, and can also be applied to a case where a crimp nut is used as a columnar member.

[0127] Next, the effects of the fastening structure according to the present disclosure will be described.

[0128] In the manufacturing process of a component assembly including a fastening structure, pressure is applied to the extent that non-contact surfaces remain, so the number of times crimping processes to expand the diameter of the tip of the columnar member can be reduced compared to conventional cases in which the tip is entirely deformed. Therefore, when the fastening structure is applied to a battery lid, pressure when crimping the external terminal acts horizontally, reducing the amount of warping of the lid.

[0129] Furthermore, the adhesion between the enlarged diameter portion of the external terminal and the rib of the current collector can be improved, and the welded portion can be stabilized.

[0130] Preferred embodiments of the present disclosure will be summarized below.

[0131] In the fastening structure, it is desirable that the fastened parts constituting the outermost surface have a rib or a countersunk portion formed therein, and that at least a portion of the outer periphery of the enlarged diameter portion be in close contact with the inner wall of the rib or countersunk portion.

[0132] It is desirable that the fastened parts constituting the outermost surface and the enlarged diameter portion are joined via a welded portion.

[0133] It is desirable that the heights of the fastened parts and the enlarged diameter portion at the weld be approximately equal.

[0134] The plurality of fastened components preferably include a gasket, an insulating block, and a current collector, and the columnar members are external terminals.

[0135] 1: electrode group, 2: case, 3: positive electrode terminal portion, 4: negative electrode terminal portion, 5: lid assembly, 11: external terminal, 11a: bus bar connection portion, 11b: current collector connection portion, 11c: enlarged diameter portion, 12: gasket, 13: lid, 14: insulating block, 15: current collector, 21: rib, 22: crimping punch, 23: recess, 24: welded portion, 27, 37: groove, 36: counterbore portion, 100: battery.

Claims

1. An electrode assembly comprising: an electrode body; a current collector connected to the electrode body; and an external terminal stacked on and connected to the current collector, wherein the current collector comprises: a main body portion; and a current collecting plate portion connected to the main body portion, wherein the main body portion has a through hole, and a rib is formed around the through hole of the main body portion, wherein the external terminal comprises: a current collector connection portion inserted into the through hole of the main body portion; and an expanded diameter portion continuous with the current collector connection portion along the stacking direction and having a dimension larger than that of the current collector connection portion in a direction intersecting the stacking direction, wherein a recess is formed at an end of the expanded diameter portion facing the electrode assembly along the stacking direction, and the expanded diameter portion has a contact portion with the rib in the direction intersecting the stacking direction, and in a cross section passing through the expanded diameter portion and the contact portion, the expanded diameter portion, or the expanded diameter portion and the current collector connection portion, has a first fixing portion to which the current collector is fixed in a direction intersecting the stacking direction, and a second fixing portion to which the current collector is fixed in the stacking direction, The battery, wherein the first fixing portion has a structure wider than the second fixing portion.

2. The battery according to claim 1, further comprising a gasket, a lid, and an insulating block, wherein the gasket, the lid, and the insulating block have through holes, the gasket, the lid, and the insulating block are stacked in this order and disposed between the external terminal and the current collector, the current collector connection portion of the external terminal is inserted into the through hole of the gasket, the lid, and the insulating block, the gasket has a sheath portion, and the sheath portion is disposed between the inner wall of the through hole of the lid and the current collector connection portion of the external terminal, and the diameter of the enlarged portion is smaller than the diameter of the through hole of the lid.

3. The battery according to claim 1, wherein a portion of said collector connection portion close to said enlarged diameter portion has a larger diameter than a portion of said collector connection portion away from said enlarged diameter portion.

4. A fastening structure comprising: a plurality of fastened parts each having a through hole; and a columnar member having an enlarged diameter portion; the plurality of fastened parts are stacked with their through holes aligned; the columnar member is inserted into the through hole; a rib is formed around the through hole of one of the plurality of stacked fastened parts which constitutes the outermost surface; the enlarged diameter portion has a contact portion with the rib in a direction intersecting the stacking direction; and in a cross section passing through the enlarged diameter portion and the contact portion, the enlarged diameter portion, or the enlarged diameter portion and the columnar member, have a first fixing portion to which the fastened parts which constitute the outermost surface in the direction intersecting the stacking direction are fixed, and a second fixing portion to which the fastened parts which constitute the outermost surface in the stacking direction are fixed; and the first fixing portion has a structure wider than the second fixing portion.

5. A fastening structure according to claim 4, wherein a portion of said columnar member closer to said enlarged diameter portion has a larger diameter than a portion of said columnar member further from said enlarged diameter portion.

6. A method for manufacturing a battery having an electrode body, a current collector connected to the electrode body, and an external terminal connected to the current collector, wherein the current collector includes a main body portion and a current collecting plate portion connected to the main body portion, the main body portion having a through hole, a rib formed around the through hole in the main body portion, and the external terminal having a bus bar connection portion and a current collector connection portion, the method comprising: inserting the current collector connection portion of the external terminal into the through hole in the main body portion of the current collector, and applying pressure with a crimping punch to the surface of the current collector connection portion opposite the bus bar connection portion, thereby forming a recess and an expanded diameter portion in the current collector connection portion.

7. A method for manufacturing a fastening structure comprising: a plurality of fastened parts having through holes; and a columnar member, wherein the plurality of fastened parts are stacked with their through holes aligned; and a rib is formed around the through hole of one of the stacked plurality of fastened parts that forms the outermost surface of the stacked plurality of fastened parts, wherein the columnar member is inserted into the through holes of the stacked plurality of fastened parts; and a crimping punch is used to apply pressure to the surface of the columnar member exposed to the fastened parts that form the outermost surface, thereby forming a recess and an enlarged diameter portion in the columnar member.

8. A battery comprising an electrode body, a case for accommodating the electrode body, and a lid assembly, wherein the lid assembly includes an external terminal, a gasket, a lid, an insulating block, and a current collector, wherein the gasket, the lid, the insulating block, and the current collector have through holes and constitute a plurality of fastened parts, wherein the external terminal has a columnar portion, wherein the gasket, the lid, the insulating block, and the current collector are stacked in this order with their respective through holes aligned, wherein the columnar portion is inserted into the through hole, and wherein at least a portion of the outer periphery of the expanded diameter portion of the columnar portion is in close contact with the inner wall of the through hole in the current collector, and wherein the tip of the expanded diameter portion has a recess, and wherein the recess has a pressing trace.

9. The battery of claim 8, wherein said tip of said enlarged diameter portion has an uncontacted surface.

10. The battery according to claim 8, wherein the current collector has a rib or a counterbore, and at least a portion of the outer periphery of the enlarged diameter portion is in close contact with the inner wall of the rib or the counterbore.

11. A fastening structure comprising: a plurality of fastened parts each having a through hole; and a columnar member having an enlarged diameter portion; the plurality of fastened parts are stacked with their through holes aligned; the columnar member is inserted into the through hole; at least a portion of the outer periphery of the enlarged diameter portion of the columnar member is in close contact with the inner wall of the through hole of one of the fastened parts that constitutes the outermost surface of the plurality of stacked fastened parts; the tip of the enlarged diameter portion has a recess; and the recess has a pressing trace.

12. The fastening structure of claim 11, wherein the tip of the enlarged portion has a non-contact surface.

13. A fastening structure as described in claim 11, wherein the fastened parts constituting the outermost surface have ribs or countersunk portions formed thereon, and at least a portion of the outer periphery of the enlarged diameter portion is in close contact with the inner wall of the rib or countersunk portion.

14. A fastening structure according to claim 11, wherein the fastened parts constituting the outermost surface and the enlarged diameter portion are joined via a welded portion.

15. The fastening structure according to claim 14, wherein the heights of the fastened parts and the enlarged diameter portion at the welded portion are approximately equal.

16. The fastening structure according to claim 11, wherein the plurality of fastened components include a gasket, an insulating block, and a current collector, and the columnar member is an external terminal.

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