Joining method

Abstract

This battery is provided with: a wound electrode group 2 wherein a separator and electrode plates are stacked and wound; and a collector plate. The electrode group 2 has a bonding region in which end parts of a plurality of electrode plates that are arranged in a radial direction B are bend in the radial direction B, and the plurality of bent end parts are bonded to the collector plate. The bonding region is sandwiched between two non-bonding regions 50 that are arranged in the circumferential direction of the electrode group 2; and a first boundary part 52, which is the boundary between the bonding region and one non-bonding region 50, and a second boundary part 54, which is the boundary between the bonding region and the other non-bonding region 50, extend substantially parallel to a specific virtual line L that passes through the winding center C of the electrode group 2 and the bonding region.

Description

[Technical Field]

[0001] The present disclosure relates to a battery including an electrode group and a current collector plate, and a method for joining the electrode group and the current collector plate. [Background technology]

[0002] Conventionally, batteries have been known in which a wound electrode group and an electrolyte are housed in a cylindrical outer can. Regarding such batteries, Patent Document 1 discloses a method of bending the end of the electrode group to form a flat welding surface and welding this welding surface to a current collector plate. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-106613 Summary of the Invention [Problem to be solved by the invention]

[0004] The present inventors have discovered a technique for improving the quality of batteries by joining current collector plates to welding surfaces formed by bending the ends of an electrode group.

[0005] The present disclosure has been made in light of these circumstances, and one of its objectives is to provide a technology for improving the quality of batteries. [Means for solving the problem]

[0006] One aspect of the present disclosure is a battery. The battery includes a wound electrode assembly in which separators and electrode plates are stacked and wound, and a current collector plate. The electrode assembly has a bonding region where the ends of multiple radially arranged electrode plates are bent radially and the bent ends are bonded to the current collector plate. The bonding region is sandwiched between two non-bonded regions aligned circumferentially of the electrode assembly, and a first boundary between the bonding region and one of the non-bonded regions and a second boundary between the bonding region and the other non-bonded region each extend substantially parallel to a predetermined imaginary line passing through the winding center of the electrode assembly and the bonding region.

[0007] Another aspect of the present disclosure is a method for joining a wound electrode group, in which separators and electrode plates are stacked and wound, to a current collector plate. This joining method includes pressing a first processing tool against ends of multiple electrode plates arranged in the radial direction of the electrode group to form first ridge lines that are substantially parallel to an imaginary line passing through the winding center of the electrode group and offset in the circumferential direction of the electrode group, pressing a second processing tool against ends of multiple electrode plates arranged in the radial direction, simultaneously with or after forming the first ridge lines, to form second ridge lines that are substantially parallel to the imaginary line and offset in the circumferential direction from the first ridge line, pressing a third processing tool against a section between the first and second ridge lines to bend the ends of the multiple electrode plates in the section in the radial direction to form a joining region, and joining the bent ends to the current collector plate in the joining region.

[0008] Any combination of the above components, and conversion of the expression of the present disclosure into a method, device, system, etc., are also valid aspects of the present disclosure. [Effects of the Invention]

[0009] According to the present disclosure, it is possible to improve the quality of batteries. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. [Figure 2] Fig. 2(A) is an exploded perspective view of the electrode group, and Fig. 2(B) is a plan view of the electrode group to which a first current collector plate is joined. [Figure 3] Fig. 3(A) is a plan view of the electrode group, and Fig. 3(B) is an enlarged view of a pair of first bonded regions and non-bonded regions. [Figure 4] 4(A) to 4(C) are diagrams showing the step of forming the first bonding region. [Figure 5] Figure 5(A) is a photograph of a section when the spacing M is 0.25D. Figure 5(B) is a photograph of the first bonding region when the spacing M is 0.25D. Figure 5(C) is a photograph of a section when the spacing M is 0.1D. Figure 5(D) is a photograph of the first bonding region when the spacing M is 0.1D. DETAILED DESCRIPTION OF THE INVENTION

[0011] The present disclosure will be described below with reference to preferred embodiments and drawings. The embodiments are illustrative and do not limit the present disclosure, and all features and combinations thereof described in the embodiments are not necessarily essential to the present disclosure. The same or equivalent components, parts, and processes shown in each drawing are designated by the same reference numerals, and redundant descriptions will be omitted where appropriate. The scale and shape of each part shown in each drawing are set for convenience to facilitate explanation and should not be interpreted as limiting unless otherwise specified. Furthermore, when terms such as "first" and "second" are used in this specification or claims, unless otherwise specified, these terms do not indicate any order or importance, but are intended to distinguish one configuration from another. Furthermore, some components that are not important for explaining the embodiments are omitted from each drawing.

[0012] FIG. 1 is a cross-sectional view of a battery 1. FIG. 2(A) is an exploded perspective view of an electrode group 2. FIG. 2(B) is a plan view of the electrode group 2 to which a first current collector plate 20 is joined. Note that the first uncoated portion 12 and the second uncoated portion 14 are not shown in FIG. 2(A). The non-joined region 50 is not shown in FIG. 2(B).

[0013] The battery 1 is, for example, a rechargeable secondary battery such as a lithium-ion battery, a nickel-metal hydride battery, or a nickel-cadmium battery. The battery 1, for example, has a structure in which an electrode group 2 is housed in an outer can 4 together with an electrolyte (not shown). The electrode group 2, for example, is cylindrical and has a spirally wound structure in which a strip-shaped first electrode plate 6 and a strip-shaped second electrode plate 8 are stacked with a strip-shaped separator 10 sandwiched between them, as shown in FIG. 2(A). In this embodiment, the first electrode plate 6 is a positive electrode plate and the second electrode plate 8 is a negative electrode plate, but the polarities of the first electrode plate 6 and the second electrode plate 8 may be reversed. The separator 10, for example, is made of a microporous film made of polypropylene resin or the like.

[0014] The first electrode plate 6 and the second electrode plate 8 have a structure in which an electrode active material layer is laminated on a current collector. In a typical lithium-ion secondary battery, the current collector is made of aluminum foil or the like for the positive electrode, and copper foil or the like for the negative electrode. The electrode active material layer can be formed by applying an electrode mixture to the surface of the current collector using a known coating device, followed by drying and rolling. The electrode mixture is obtained by kneading and uniformly dispersing materials such as the electrode active material, binder, and conductive material in a dispersion medium. In a typical lithium-ion secondary battery, the electrode active material is lithium cobalt oxide or lithium iron phosphate or the like for the positive electrode, and graphite or the like for the negative electrode.

[0015] The first electrode plate 6 has a first uncoated portion 12, which is not coated with the electrode composite, at one end in the width direction A (the direction intersecting the longitudinal direction of the strip). The first uncoated portion 12 is an exposed portion of the current collector of the first electrode plate 6 where no electrode active material layer is laminated. The second electrode plate 8 has a second uncoated portion 14, which is not coated with the electrode composite, at the other side in the width direction A, i.e., the end opposite the side from which the first uncoated portion 12 protrudes. The second uncoated portion 14 is an exposed portion of the current collector of the second electrode plate 8 where no electrode active material layer is laminated.

[0016] As described above, the electrode group 2 has a structure in which the first electrode plate 6 and the second electrode plate 8 are wound. Therefore, multiple ends of the first electrode plate 6 and the second electrode plate 8 in the width direction A are aligned in the radial direction B of the electrode group 2. Therefore, the electrode group 2 has multiple first uncoated portions 12 aligned in the radial direction B and multiple second uncoated portions 14 aligned in the radial direction B.

[0017] The electrode group 2 has first bonding regions 46 in which the ends (first uncoated portions 12) of the multiple first electrode plates 6 arranged in the radial direction B are bent in the radial direction B. In this embodiment, each of the first uncoated portions 12 is bent toward the winding center C of the electrode group 2, that is, toward the inside in the radial direction B. The winding center C is, for example, the geometric center of the outline of the electrode group 2 as viewed from the width direction A, in other words, the geometric center of the outline of the projected shape of the electrode group 2 in the width direction A. As an example, the electrode group 2 has multiple first bonding regions 46 spaced at predetermined intervals in the circumferential direction of the electrode group 2. As shown in FIG. 2(B), the electrode group 2 of this embodiment has four first bonding regions 46 spaced at 90° intervals in the circumferential direction.

[0018] The electrode group 2 also has second bonding regions 48 in which the ends (second uncoated portions 14) of the multiple second electrode plates 8 aligned in the radial direction B are bent in the radial direction B. In this embodiment, each second uncoated portion 14 is bent toward the winding center C. As an example, the electrode group 2 has multiple second bonding regions 48 spaced at predetermined intervals in the circumferential direction of the electrode group 2. The electrode group 2 of this embodiment has four second bonding regions 48 spaced at 90° intervals in the circumferential direction. Note that the electrode group 2 may have only one of the first bonding region 46 and the second bonding region 48. The first bonding region 46 and the second bonding region 48 will be described in detail later.

[0019] A first current collector plate 20 is disposed on the side of the electrode group 2 from which the first uncoated portion 12 protrudes. The first current collector plate 20 is made of, for example, aluminum. The ends of the multiple first electrode plates 6 bent in the first joint region 46 come into surface contact with the first current collector plate 20. By bending the end of each first electrode plate 6, the contact area between each first uncoated portion 12 and the first current collector plate 20 increases. Then, laser welding or the like is performed at the position where the first joint region 46 and the first current collector plate 20 overlap, forming a joint 44. This joins the first electrode plate 6 and the first current collector plate 20 of each winding layer to each other.

[0020] A second current collector plate 22 is disposed on the side of the electrode group 2 from which the second uncoated portion 14 protrudes. The second current collector plate 22 is made of, for example, copper, nickel, nickel-plated copper, or nickel-plated iron. The ends of the multiple second electrode plates 8 bent in the second bonding regions 48 come into surface contact with the second current collector plate 22. The bending of the ends of each second electrode plate 8 increases the contact area between each second uncoated portion 14 and the second current collector plate 22. Then, a bonding portion (not shown) is formed by laser welding or the like at the position where the second bonding region 48 and the second current collector plate 22 overlap. This bonds the second electrode plate 8 and the second current collector plate 22 of each winding layer to each other.

[0021] The electrode group 2, in which the first current collector plate 20 and the second current collector plate 22 are joined, is housed together with the electrolyte in a cylindrical outer can 4 with a bottom. The outer can 4 is made of, for example, copper, nickel, iron, or an alloy of these. The second current collector plate 22 is joined to the inner bottom surface of the outer can 4 by welding or the like. The first current collector plate 20 is joined to a sealing plate 26, which is made of the same metal as the outer can 4, by welding or the like. The sealing plate 26 is fitted into the opening of the outer can 4 via an insulating gasket 24. This seals the electrode group 2 and the electrolyte inside the outer can 4.

[0022] Next, the shape of the bonding region will be described. Fig. 3(A) is a plan view of the electrode group 2. Fig. 3(B) is an enlarged view of a pair of a first bonding region 46 and a non-bonding region 50. Below, the shape of the bonding region will be described using the first bonding region 46 as an example. The shape of the second bonding region 48 is the same as that of the first bonding region 46.

[0023] As described above, the electrode group 2 of this embodiment has four first bonding regions 46. The first bonding regions 46 are offset from one another by 90° in the circumferential direction of the electrode group 2. Each first bonding region 46 is a substantially rectangular region extending in the radial direction B. Each first bonding region 46 is sandwiched between two non-bonding regions 50 that are aligned in the circumferential direction of the electrode group 2. Each non-bonding region 50 is recessed in the width direction A from the first bonding region 46, and is a region that is not substantially bonded to the first electrode plate 6.

[0024] Each first bonding region 46 has a first boundary 52 and a second boundary 54. The first boundary 52 is the boundary between the first bonding region 46 and one of the non-bonding regions 50. The second boundary 54 is the boundary between the first bonding region 46 and the other non-bonding region 50. The first boundary 52 and the second boundary 54 are aligned with each other in the circumferential direction of the electrode group 2.

[0025] The first boundary 52 and the second boundary 54 each extend substantially parallel to a predetermined imaginary line L that passes through the winding center C of the electrode group 2 and the first bonding region 46. Therefore, the first boundary 52 and the second boundary 54 extend substantially parallel to each other. In this embodiment, "substantially parallel" refers not only to being completely parallel to the other side (such as the imaginary line L or the second boundary 54 relative to the first boundary 52), but also to being slightly displaced from the other side at each position in the radial direction B, for example, by an amount of displacement less than 0.075D (described later). The imaginary line L is a straight line located midway between the first boundary 52 and the second boundary 54. For example, the imaginary line L is a straight line that passes through the geometric center of the outline of the first bonding region 46 as viewed in the width direction A and the winding center C. By having the two boundaries extend substantially parallel, the bending range of the end of the first electrode plate 6 can be made uniform in each winding layer. This makes it possible to make uniform the bonding area between the first electrode plate 6 and the first current collector plate 20 in each winding layer, and improves the bonding stability between the electrode group 2 and the first current collector plate 20.

[0026] When the diameter of the electrode group 2 is D, the deviation of each of the first boundary 52 and the second boundary 54 in the direction perpendicular to the virtual line L is preferably less than 0.075D. That is, the distance between the closest and farthest points of each boundary in the direction perpendicular to the virtual line L, in other words, the parallelism of each boundary with respect to the virtual line L, is less than 0.075D. The diameter D is, for example, the average of the maximum and minimum outer diameters of the electrode group 2 as viewed from the width direction A, and is, for example, 15 mm to 50 mm. It is desirable that each boundary be completely parallel to the virtual line L. However, even if the boundary meanders with respect to the virtual line L, by keeping the deviation of each boundary in the direction perpendicular to the virtual line L to less than 0.075 times the diameter D, it is possible to prevent difficulty in achieving uniform bonding areas between the first electrode plate 6 and the first current collector plate 20 in each winding layer.

[0027] When the distance M between the first boundary portion 52 and the second boundary portion 54 at each position in the radial direction B and the diameter D of the electrode group 2 are considered, preferably the distance M satisfies 0.1D < M < 0.25D. The distance M is the distance in the direction orthogonal to the virtual line L between the first boundary portion 52 and the second boundary portion 54 at each position in the radial direction B. By setting the distance M to be more than 0.1 times and less than 0.25 times the diameter D of the electrode group 2, it becomes easier to equalize the bonding area between the first electrode plate 6 and the first current collector plate 20 in each winding layer.

[0028] Preferably, the first bonding region 46 extends to the outer edge in the radial direction B of the electrode group 2. Thereby, it becomes easier to equalize the bonding area between the first electrode plate 6 and the first current collector plate 20 in each winding layer. The dimension of the first bonding region 46 in the radial direction B is preferably 0.1D or more.

[0029] Next, the bonding method between the electrode group 2 and the current collector plate will be described. Hereinafter, taking the bonding of the first bonding region 46 and the first current collector plate 20 as an example, the bonding method between the electrode group 2 and the current collector plate will be described. The bonding of the second bonding region 48 and the second current collector plate 22 is the same as that of the first bonding region 46. Note that only one of the first bonding region 46 and the second bonding region 48 may be formed by the method according to the present embodiment and bonded to the current collector plate. FIGS. 4(A) to 4(C) are diagrams showing the formation process of the first bonding region 46.

[0030] First, as shown in FIG. 2(A), strip-shaped first electrode plates 6, second electrode plates 8, and separators 10 are prepared respectively. Then, the separator 10, the first electrode plate 6, the separator 10, and the second electrode plate 8 are laminated in this order. The obtained laminate is wound in a spiral shape to form a wound-type electrode group 2.

[0031] Next, as shown in FIG. 4(A), in a predetermined region of the electrode group 2, a first processing tool 56 is pressed against the ends of the multiple first electrode plates 6 lined up in the radial direction B, i.e., the multiple first uncoated portions 12, to bend the ends of the multiple first electrode plates 6 in the radial direction B. As an example, the end of each first electrode plate 6 is bent inward in the radial direction B. The first processing tool 56 has a surface parallel to an imaginary line L passing through the winding center C, and presses the ends of the multiple first electrode plates 6 with this surface. This forms a first ridge line 58 that is substantially parallel to the imaginary line L and is shifted in the circumferential direction of the electrode group 2 with respect to the imaginary line L.

[0032] Furthermore, a second processing tool 60 is pressed against the ends of the plurality of first electrode plates 6 arranged in the radial direction B, thereby bending the ends of the plurality of first electrode plates 6 in the radial direction B. The second processing tool 60 has a surface parallel to the imaginary line L, and presses the ends of the plurality of first electrode plates 6 with this surface. The second processing tool 60 also presses an area of ​​the electrode group 2 arranged in the circumferential direction across the imaginary line L from the area pressed by the first processing tool 56. This forms a second ridge line 62 that is substantially parallel to the imaginary line L and displaced in the circumferential direction from the first ridge line 58; in other words, the second ridge line 62 is arranged in the circumferential direction with the first ridge line 58 across the imaginary line L. The second ridge line 62 may be formed simultaneously with the formation of the first ridge line 58 or after the formation of the first ridge line 58.

[0033] When forming the first ridge line 58 and the second ridge line 62, it is preferable to displace the first processing tool 56 and the second processing tool 60 pressed against the end of each first electrode plate 6 in the radial direction B and in a direction approaching the imaginary line L. As an example, the first processing tool 56 and the second processing tool 60 in this embodiment move in a direction approaching the winding center C from the outside in the radial direction B, while also moving in a direction approaching the imaginary line L. In this way, by moving the first processing tool 56 and the second processing tool 60 obliquely with respect to the region where the first joining region 46 is to be formed while pressing them against the electrode group 2, it is possible to easily form the first ridge line 58 and the second ridge line 62 that are parallel to the imaginary line L.

[0034] Furthermore, it is more preferable to displace the first processing tool 56 and the second processing tool 60 on a curved trajectory so that the amount of displacement in the radial direction B gradually decreases and the amount of displacement in the direction approaching the imaginary line L gradually increases. For example, in the early stages of displacement, the first processing tool 56 and the second processing tool 60 are displaced more in the direction approaching the winding center C than in the direction approaching the imaginary line L. Then, during the displacement process, the amount of displacement in the direction approaching the imaginary line L gradually increases and the amount of displacement in the direction approaching the winding center C gradually decreases. As a result, in the later stages of displacement, the first processing tool 56 and the second processing tool 60 are displaced more in the direction approaching the imaginary line L than in the direction approaching the winding center C.

[0035] That is, the displacement of the first processing tool 56 and the second processing tool 60 transitions from a state in which the amount of displacement in the radial direction B is greater than the amount of displacement in the direction approaching the imaginary line L to a state in which the amount of displacement in the direction approaching the imaginary line L is greater than the amount of displacement in the radial direction B. By displacing each processing tool along a curved trajectory, in the early stage of the displacement of each processing tool, the end of each first electrode plate 6 is preferentially bent in the radial direction B, and in the later stage of the displacement, the end of each first electrode plate 6 that has fallen in the radial direction B is pressed toward the imaginary line L, thereby forming each ridge line. This makes it easier to form the first ridge line 58 and the second ridge line 62 that are parallel to the imaginary line L.

[0036] Next, as shown in FIG. 4(B), a third processing tool 66 is pressed against a section 64 sandwiched between the first ridge line 58 and the second ridge line 62. As an example, the third processing tool 66 has a width approximately equal to the distance M between the first ridge line 58 and the second ridge line 62 and a surface facing the electrode group 2 in the width direction A, and moves in the radial direction B while pressing this surface against the section 64. For example, the third processing tool 66 moves from the outside in the radial direction B in a direction approaching the winding center C. When the third processing tool 66 is pressed against the section 64, the ends of the multiple first electrode plates 6 are bent inward in the radial direction B, starting from the first ridge line 58 and the second ridge line 62.

[0037] 4(C), a substantially rectangular first bonding region 46 extending in the radial direction B is formed. The portion depressed by the first processing tool 56 and the portion depressed by the second processing tool 60 form a non-bonding region 50. The first ridge line 58 forms a first boundary portion 52, and the second ridge line 62 forms a second boundary portion 54.

[0038] In the wound electrode group 2, the first electrode plates 6 located on the outside in the radial direction B are curved with a smaller curvature than the first electrode plates 6 located on the inside in the radial direction B. Therefore, the outer first electrode plates 6 are more likely to bend in the radial direction B than the inner first electrode plates 6. For this reason, if the section 64 is pressed with the third processing tool 66 without providing the first ridge lines 58 and the second ridge lines 62, the outer first electrode plates 6 tend to bend at a deeper position than the inner first electrode plates 6, that is, at a position farther from the end in the width direction A. The deeper the bending position, the larger the portion that falls in the radial direction B. Therefore, the size of the contact area between the first electrode plates 6 and the first current collector plate 20 varies among the winding layers.

[0039] In contrast, when the first ridge line 58 and the second ridge line 62 are provided to extend substantially parallel to each other, the first electrode plate 6 of each winding layer is bent starting from the pair of ridge lines. This makes it possible to uniformize the width of the bent portion of each first electrode plate 6 (the dimension in the direction perpendicular to the imaginary line L). Furthermore, by making the width of the bent portion uniform, it is possible to uniformize the depth of the bent portion of each first electrode plate 6. This allows the end of the first electrode plate 6 located on the outer side to be bent in the same manner as the end of the first electrode plate 6 located on the inner side. This makes it possible to uniformize the bonding area between the first electrode plate 6 and the first current collector plate 20 in each winding layer.

[0040] The first ridge line 58 and the second ridge line 62 are preferably formed so as to contact the outer edge in the radial direction B of the electrode group 2. That is, the first ridge line 58 and the second ridge line 62 extend to the outer edge of the electrode group 2. Thereby, the outermost first electrode plate 6, which tends to bend at the deepest position, can be bent in the same manner as the other first electrode plates 6. Therefore, it is possible to make the bonding area between the first electrode plate 6 and the first current collector plate 20 uniform in each winding layer.

[0041] The first ridge line 58 and the second ridge line 62 are preferably formed so as to extend within a range where the amount of deviation in the direction orthogonal to the virtual line L is less than 0.075D. Thereby, it becomes easier to bend the first electrode plate 6 of each winding layer more uniformly. As a result, it is possible to make the bonding area between the first electrode plate 6 and the first current collector plate 20 uniform in each winding layer.

[0042] The first ridge line 58 and the second ridge line 62 are preferably formed so that the interval M between the first ridge line 58 and the second ridge line 62 at each position in the radial direction B satisfies 0.1D < M < 0.25D. FIG. 5(A) is a photograph of the partition 64 when the interval M is 0.25D. FIG. 5(B) is a photograph of the first bonding region 46 when the interval M is 0.25D. FIG. 5(C) is a photograph of the partition 64 when the interval M is 0.1D. FIG. 5(D) is a photograph of the first bonding region 46 when the interval M is 0.1D.

[0043] As shown in FIGS. 5(A) and 5(B), as a result of intensive studies by the inventors, it has been found that when the interval M becomes 0.25 times or more of the diameter D of the electrode group 2, an event in which the outer first electrode plate 6 in the radial direction B bends at a deeper position than the inner first electrode plate 6 is likely to occur. Further, as shown in FIGS. 5(C) and 5(D), when the interval M becomes 0.1 times or less of the diameter D, the amount of deflection of each first electrode plate 6 in the circumferential direction of the electrode group 2 becomes excessive, and wrinkles are likely to occur when each first electrode plate 6 is bent by the third processing tool 66. When wrinkles occur in the first bonding region 46, it becomes difficult to make the bonding area between the first electrode plate 6 and the first current collector plate 20 uniform in each winding layer.

[0044] Therefore, by forming each ridge line so that the interval M satisfies 0.1D < M < 0.25D, the depth of the bending position of each first electrode plate 6 can be made more uniform, and the occurrence of wrinkles in the first bonding region 46 can be suppressed. As a result, it becomes easier to make the bonding area between the first electrode plate 6 and the first current collector plate 20 uniform in each winding layer.

[0045] The above-described processing is also performed on other regions of the electrode group 2 to form other first bonding regions 46. Some or all of the first bonding regions 46 may be formed simultaneously. After all the first bonding regions 46 are formed, as shown in FIG. 2(B), the ends of the plurality of first electrode plates 6 bent in the first bonding region 46 and the first current collector plate 20 are joined.

[0046] The same processing is also performed on the ends of the plurality of second electrode plates 8 to form the second bonding region 48. Then, the second current collector plate 22 is joined to the ends of the plurality of second electrode plates 8 bent in the second bonding region 48. The electrode group 2 in which the first current collector plate 20 and the second current collector plate 22 are joined is housed in the exterior can 4 together with the electrolytic solution. Then, processes such as joining the second current collector plate 22 and the exterior can 4, joining the first current collector plate 20 and the sealing plate 26, and fitting the sealing plate 26 into the opening of the exterior can 4 are performed. Thereby, the battery 1 is obtained.

[0047] As described above, in the electrode group 2 included in the battery 1 according to the present embodiment, the ends of a plurality of electrode plates (at least one of the first electrode plate 6 and the second electrode plate 8) arranged in the radial direction B are bent in the radial direction B, and the ends of the plurality of bent electrode plates are joined to a current collector plate (at least one of the first current collector plate 20 and the second current collector plate 22) to have a bonding region (at least one of the first bonding region 46 and the second bonding region 48). The bonding region is sandwiched between two non-bonding regions 50 arranged in the circumferential direction of the electrode group 2. The first boundary portion 52 and the second boundary portion 54, which are the boundaries between the bonding region and each non-bonding region 50, extend substantially parallel to the virtual line L passing through the winding center C and the bonding region.

[0048] By having the two boundary portions extend substantially parallel to each other, the electrode plates of each winding layer can be bent more uniformly. As a result, the bonding area between the electrode plates of each winding layer and the current collector plate can be made uniform, and the bonding stability between the electrode group 2 and the current collector plate can be enhanced. Therefore, the quality of the battery 1 can be improved.

[0049] In addition, the first boundary portion 52 and the second boundary portion 54 of the present embodiment extend within a range where the amount of deviation in the direction orthogonal to the virtual line L is less than 0.075D. Also, the distance M between the first boundary portion 52 and the second boundary portion 54 at each position in the radial direction B satisfies 0.1D < M < 0.25D. Moreover, the bonding region extends to the outer edge in the radial direction B in the electrode group 2. By these means, it is possible to more easily make the bonding area between the electrode plates and the current collector plate in each winding layer uniform.

[0050] In addition, the bonding method between the electrode group 2 according to the present embodiment and the current collector plate (at least one of the first current collector plate 20 and the second current collector plate 22) is to press the first tool 56 against the ends of a plurality of electrode plates (at least one of the first electrode plate 6 and the second electrode plate 8) arranged in the radial direction B to form a first ridge line 58 that is substantially parallel to the virtual line L and displaced in the circumferential direction of the electrode group 2. Simultaneously with or after the formation of the first ridge line 58, the second tool 60 is pressed against the ends of a plurality of electrode plates arranged in the radial direction B to form a second ridge line 62 that is substantially parallel to the virtual line L and displaced in the circumferential direction with respect to the first ridge line 58. The third tool 66 is pressed against the section 64 sandwiched between the first ridge line 58 and the second ridge line 62 to bend the ends of the plurality of electrode plates in the section 64 in the radial direction B to form a bonding region (at least one of the first bonding region 46 and the second bonding region 48), and includes bonding the ends of the plurality of bent electrode plates in the bonding region to the current collector plate.

[0051] A first ridge line 58 and a second ridge line 62 that are substantially parallel to each other are provided, and by using the pair of ridge lines as the starting points for bending the electrode plates in each winding layer, each electrode plate can be bent more uniformly. As a result, the joint area between the electrode plates and the current collector plate in each winding layer can be made uniform, and the joint stability between the electrode group 2 and the current collector plate can be enhanced. Therefore, the quality of the battery 1 can be improved.

[0052] In addition, the joining method of the present embodiment includes displacing the first tool 56 and the second tool 60 in the radial direction B and in the direction approaching the virtual line L. Further, the joining method of the present embodiment includes displacing the first tool 56 and the second tool 60 along a curved trajectory such that the displacement amount in the radial direction B gradually decreases and the displacement amount in the direction approaching the virtual line L gradually increases. By these means, it becomes easier to form the first ridge line 58 and the second ridge line 62 parallel to the virtual line L. Therefore, it becomes easier to make the joint area between the electrode plates and the current collector plate in each winding layer more uniform.

[0053] In addition, the joining method of the present embodiment includes forming the first ridge line 58 and the second ridge line 62 so as to extend within a range where the amount of deviation in the direction orthogonal to the virtual line L is less than 0.075D. Further, it includes forming the first ridge line 58 and the second ridge line 62 such that the interval M between the first ridge line 58 and the second ridge line 62 at each position in the radial direction B satisfies 0.1D < M < 0.25D. Further, it includes forming the first ridge line 58 and the second ridge line 62 so as to contact the outer edge in the radial direction B of the electrode group 2. By these means, it becomes easier to make the joint area between the electrode plates and the current collector plate in each winding layer more uniform.

[0054] The embodiments of the present disclosure have been described in detail above. The above-described embodiments merely illustrate specific examples of implementing the present disclosure. The content of the embodiments does not limit the technical scope of the present disclosure, and many design modifications, such as changing, adding, or deleting components, are possible within the scope of the invention defined in the claims. A new embodiment with design modifications will combine the effects of the combined embodiments and modifications. In the above-described embodiments, content that allows such design modifications is emphasized by using notations such as "in this embodiment" or "in this embodiment," but design modifications are also permitted even in content without such notation. Furthermore, any combination of components included in each embodiment is also valid as an aspect of the present disclosure. Hatching on cross sections in the drawings does not limit the material of the hatched object.

[0055] The embodiments may be specified by the following items. [1st item] a wound electrode group (2) in which a separator (10) and electrode plates (6, 8) are stacked and wound; current collecting plates (20, 22), the electrode group (2) has joining regions (46, 48) in which the ends of the plurality of electrode plates (6, 8) arranged in the radial direction (B) are bent in the radial direction (B), and the bent ends are joined to the current collector plates (20, 22); The bonded regions (46, 48) are sandwiched between two non-bonded regions (50) arranged side by side in the circumferential direction of the electrode group (2), and a first boundary (52) which is a boundary between the bonded region (46, 48) and one of the non-bonded regions (50), and a second boundary (54) which is a boundary between the bonded region (46, 48) and the other non-bonded region (50), each extend substantially parallel to a predetermined imaginary line (L) which passes through the winding center (C) of the electrode group (2) and the bonded regions (46, 48). Batteries (1). [Second item] When the diameter of the electrode group (2) is D, the first boundary (52) and the second boundary (54) each extend within a range of a deviation of less than 0.075D in a direction perpendicular to the virtual line (L). The battery (1) according to Item 1. [Item 3] When the distance M between the first boundary portion (52) and the second boundary portion (54) at each position in the radial direction (B) and the diameter D of the electrode group (2) are defined, the distance M satisfies 0.1D < M < 0.25D. The battery (1) according to Item 1 or Item 2. [Item 4] The joining regions (46, 48) extend to the outer edge in the radial direction (B) of the electrode group (2). The battery (1) according to any one of Items 1 to 3. [Item 5] A joining method of a wound electrode group (2) in which a separator (10) and electrode plates (6, 8) are laminated and wound, and current collector plates (20, 22), A first tool (56) is pressed against the ends of a plurality of electrode plates (6, 8) arranged in the radial direction (B) of the electrode group (2) to form a first ridge line (58) that is substantially parallel to a virtual line (L) passing through the winding center (C) of the electrode group (2) and is displaced in the circumferential direction of the electrode group (2), Simultaneously with or after the formation of the first ridge line (58), a second tool (60) is pressed against the ends of a plurality of electrode plates (6, 8) arranged in the radial direction (B) to form a second ridge line (62) that is substantially parallel to the virtual line (L) and is displaced in the circumferential direction with respect to the first ridge line (58), A third tool (66) is pressed against a section (64) sandwiched between the first ridge line (58) and the second ridge line (62) to bend the ends of the plurality of electrode plates (6, 8) in the section (64) in the radial direction (B) to form joining regions (46, 48), including joining the bent plurality of ends and the current collector plates (20, 22) in the joining regions (46, 48). Joining method. [Item 6] including displacing the first tool (56) and the second tool (60) in the radial direction (B) and the direction approaching the virtual line (L). The joining method according to Item 5. [Item 7] Displacing the first tool (56) and the second tool (60) along a curved path such that the displacement amount in the radial direction (B) gradually decreases and the displacement amount in the direction approaching the virtual line (L) gradually increases, The joining method according to Item 6. [Item 8] When the diameter of the electrode group (2) is D, forming the first ridge line (58) and the second ridge line (62) so as to extend within a range where the displacement amount in the direction orthogonal to the virtual line (L) is less than 0.075D, The joining method according to any one of Items 5 to 7. [Item 9] When the distance between the first ridge line (58) and the second ridge line (62) at each position in the radial direction (B) is M and the diameter of the electrode group (2) is D, forming the first ridge line (58) and the second ridge line (62) such that the distance M satisfies 0.1D < M < 0.25D, The joining method according to any one of Items 5 to 8. [Item 10] Forming the first ridge line (58) and the second ridge line (62) so as to contact the outer edge in the radial direction (B) of the electrode group (2), The joining method according to any one of Items 5 to 9.

Industrial Applicability

[0056] The present disclosure can be used for a battery including an electrode group and a current collector plate, and a method for joining the electrode group and the current collector plate.

Explanation of Signs

[0057] 1 Battery, 2 Electrode group, 6 First electrode plate, 8 Second electrode plate, 10 Separator, 20 First current collector plate, 22 Second current collector plate, 46 First joining region, 48 Second joining region, 50 Non-joining region, 52 First boundary portion, 54 Second boundary portion, 56 First tool, 58 First ridge line, 60 Second tool, 62 Second ridge line, 64 Compartment, 66 Third tool.

Claims

1. A method for joining a wound electrode group, in which separators and electrode plates are stacked and wound, to a current collector plate, comprising the steps of: a first processing tool is pressed against ends of the plurality of electrode plates arranged in the radial direction of the electrode group to form a first ridge line that is substantially parallel to an imaginary line passing through a winding center of the electrode group and is shifted in the circumferential direction of the electrode group; simultaneously with or after the formation of the first ridge lines, a second processing tool is pressed against the ends of the plurality of electrode plates arranged in the radial direction to form second ridge lines that are substantially parallel to the imaginary line and displaced in the circumferential direction from the first ridge lines; a third processing tool is pressed against a section sandwiched between the first ridge line and the second ridge line to bend ends of the plurality of electrode plates in the section in the radial direction to form a joining region; and joining the bent end portions to the current collector plate in the joining region. Joining method.

2. displacing the first processing tool and the second processing tool in the radial direction and in a direction approaching the virtual line, The joining method according to claim 1 .

3. displacing the first processing tool and the second processing tool along a curved trajectory such that the amount of displacement in the radial direction gradually decreases and the amount of displacement in a direction approaching the virtual line gradually increases. The joining method according to claim 2 .

4. forming the first ridge line and the second ridge line so that a deviation amount in a direction perpendicular to the virtual line is less than 0.075D, where D is a diameter of the electrode group; The joining method according to any one of claims 1 to 3.

5. forming the first ridge lines and the second ridge lines so that the distance M satisfies 0.1D<M<0.25D, where M is a distance between the first ridge lines and the second ridge lines at each position in the radial direction and D is a diameter of the electrode group; The joining method according to any one of claims 1 to 3.

6. forming the first ridge line and the second ridge line so as to be in contact with an outer edge of the electrode group in the radial direction; The joining method according to any one of claims 1 to 3.

Images