Battery

Abstract

We aim to improve battery quality. [Solution] The battery comprises a wound electrode group 2 in which separators and electrode plates are stacked and wound, and a current collector plate. The electrode group 2 has a bonding region in which the ends of a plurality of electrode plates arranged in the radial direction B are bent in the radial direction B, and the bent plurality of ends are joined to the current collector plate. The bonding region is sandwiched between two non-bonding regions 50 arranged in the circumferential direction of the electrode group 2, and the first boundary portion 52, which is the boundary between the bonding region and one of the non-bonding regions 50, and the second boundary portion 54, which is the boundary between the bonding region and the other non-bonding region 50, each extend substantially parallel to a predetermined imaginary line L passing 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 Art

[0002] Conventionally, a battery in which a wound electrode group and an electrolytic solution are housed in a cylindrical exterior can is known. Regarding such a battery, Patent Document 1 discloses a method in which an end portion of the electrode group is bent to form a flat welding surface, and this welding surface and the current collector plate are welded.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The inventors of the present invention have found a technique for improving the quality of a battery in a method of joining a current collector plate to a welding surface formed by bending an end portion of an electrode group.

[0005] The present disclosure has been made in view of such circumstances, and one of its objects is to provide a technique for improving the quality of a battery.

Means for Solving the Problems

[0006] One aspect of the present disclosure is a battery. The battery comprises a wound electrode group in which separators and electrode plates are stacked and wound, and a current collector plate. The electrode group has a bonding region in which the ends of a plurality of radially aligned electrode plates are bent radially, and the bent ends are joined to the current collector plate. The bonding region is sandwiched between two non-bonding regions aligned circumferentially of the electrode group, and a first boundary portion, which is the boundary between the bonding region and one of the non-bonding regions, and a second boundary portion, which is the boundary between the bonding region and the other non-bonding region, each extend substantially parallel to a predetermined imaginary line passing through the winding center of the electrode group 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 together, to a current collector plate. This joining method includes pressing a first tool against the ends of a plurality of electrode plates arranged radially in the electrode group to form a first ridge that is substantially parallel to a virtual line passing through the winding center of the electrode group and offset in the circumferential direction of the electrode group; simultaneously with or after the formation of the first ridge, pressing a second tool against the ends of a plurality of electrode plates arranged radially to form a second ridge that is substantially parallel to the virtual line and offset in the circumferential direction with respect to the first ridge; pressing a third tool against the section sandwiched between the first and second ridges to bend the ends of the plurality of electrode plates in the section radially to form a joining region; and joining the bent ends in the joining region to the current collector plate.

[0008] Any combination of the above components, as well as any conversion of the expressions of this disclosure between methods, apparatus, systems, etc., are also valid forms of this disclosure. [Effects of the Invention]

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

[0010] [Figure 1] This is a cross-sectional view of a battery. [Figure 2] Figure 2(A) is an exploded perspective view of the electrode group. Figure 2(B) is a plan view of the electrode group to which the first current collector plate is attached. [Figure 3] Figure 3(A) is a plan view of the electrode group. Figure 3(B) is an enlarged view of a pair of first junction and non-junction regions. [Figure 4] Figures 4(A) to 4(C) show the process of forming the first bonding region. [Figure 5] Figure 5(A) is a photograph of the section when the spacing M is 0.25D. Figure 5(B) is a photograph of the first joint region when the spacing M is 0.25D. Figure 5(C) is a photograph of the section when the spacing M is 0.1D. Figure 5(D) is a photograph of the first joint region when the spacing M is 0.1D. [Modes for carrying out the invention]

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

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

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

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

[0015] The first electrode plate 6 has a first uncoated portion 12 at one end in the width direction A (the direction intersecting the longitudinal direction of the strip) where the electrode composite material is not applied. The first uncoated portion 12 is an exposed portion of the current collector of the first electrode plate 6 where the electrode active material layer is not laminated. The second electrode plate 8 also has a second uncoated portion 14 at the other end in the width direction A, that is, the end opposite to the side from which the first uncoated portion 12 protrudes, where the electrode composite material is not applied. The second uncoated portion 14 is an exposed portion of the current collector of the second electrode plate 8 where the electrode active material layer is not laminated.

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

[0017] The electrode group 2 has a first bonding region 46 formed by the ends (first uncoated portions 12) of a plurality of first electrode plates 6 arranged in the radial direction B being bent in the radial direction B. Each first uncoated portion 12 in this embodiment is bent toward the winding center C of the electrode group 2, that is, inward in the radial direction B. The winding center C is, for example, the geometric center of the outer shape of the electrode group 2 as viewed from the width direction A, in other words, the geometric center of the outer shape of the projection of the electrode group 2 toward the width direction A. As an example, the electrode group 2 has a plurality of first bonding regions 46 spaced at predetermined intervals in the circumferential direction of the electrode group 2. As shown in Figure 2(B), the electrode group 2 in this embodiment has four first bonding regions 46 spaced at 90° intervals in the circumferential direction.

[0018] Furthermore, the electrode group 2 has a second bonding region 48 where the ends (second uncoated portions 14) of a plurality of second electrode plates 8 arranged in the radial direction B are bent in the radial direction B. Each second uncoated portion 14 in this embodiment is bent toward the winding center C. As an example, the electrode group 2 has a plurality of second bonding regions 48 spaced at predetermined intervals in the circumferential direction of the electrode group 2. The electrode group 2 in 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] On the side where the first uncoated portion 12 in the electrode group 2 protrudes, the first current collector plate 20 is arranged. The first current collector plate 20 is made of, for example, aluminum or the like. The ends of the plurality of first electrode plates 6 bent in the first joints area 46 are in surface contact with the first current collector plate 20. By bending the ends of each of the first electrode plates 6, the contact area between each of the first uncoated portions 12 and the first current collector plate 20 increases. A laser welding or the like is performed at the position where the first joints area 46 and the first current collector plate 20 overlap, thereby forming the joint portion 44. Thus, the first electrode plates 6 and the first current collector plate 20 in each winding layer are joined to each other.

[0020] On the side where the second uncoated portion 14 in the electrode group 2 protrudes, the second current collector plate 22 is arranged. The second current collector plate 22 is made of, for example, copper, nickel, copper plated with nickel, iron plated with nickel, or the like. The ends of the plurality of second electrode plates 8 bent in the second joints area 48 are in surface contact with the second current collector plate 22. By bending the ends of each of the second electrode plates 8, the contact area between each of the second uncoated portions 14 and the second current collector plate 22 increases. A laser welding or the like is performed at the position where the second joints area 48 and the second current collector plate 22 overlap, thereby forming a joint portion (not shown). Thus, the second electrode plates 8 and the second current collector plate 22 in each winding layer are joined 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 electrolytic solution in a bottomed cylindrical exterior can 4. The exterior can 4 is made of, for example, copper, nickel, iron, or an alloy thereof. The second current collector plate 22 is joined to the inner bottom surface of the exterior can 4 by welding or the like. The first current collector plate 20 is joined to a sealing plate 26 made of the same metal as the exterior can 4 by welding or the like. The sealing plate 26 is fitted into the opening of the exterior can 4 via an insulating gasket 24. Thus, the electrode group 2 and the electrolytic solution are sealed inside the exterior can 4.

[0022] Next, the shape of the bonding region will be described. Figure 3(A) is a plan view of electrode group 2. Figure 3(B) is an enlarged view of a pair of first bonding regions 46 and non-bonding regions 50. In the following, 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. Each first bonding region 46 is offset from each other 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. Furthermore, 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 compared to the first bonding region 46 and is a region that is substantially not bonded to the first electrode plate 6.

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

[0025] The first boundary section 52 and the second boundary section 54 each extend substantially parallel to a predetermined virtual line L passing through the winding center C and the first junction region 46 of the electrode group 2. Therefore, the first boundary section 52 and the second boundary section 54 extend substantially parallel to each other. In this embodiment, "substantially parallel" means not only when they are perfectly parallel to the other side (such as the virtual line L or the second boundary section 54 relative to the first boundary section 52), but also when the distance from the other side at each position in the radial direction B is slightly shifted, for example, when the boundary section extends with a shift amount of less than 0.075D, as described later. The virtual line L is a straight line located midway between the first boundary section 52 and the second boundary section 54. For example, the virtual line L is a straight line passing through the geometric center of the outer shape of the first junction region 46 as viewed from the width direction A and the winding center C. By having the two boundary sections extend substantially parallel to each other, the range in which the ends of the first electrode plate 6 are bent in each winding layer can be made uniform. This makes it possible to equalize the bonding area between the first electrode plate 6 and the first current collector plate 20 in each winding layer, thereby improving the bonding stability between the electrode group 2 and the first current collector plate 20.

[0026] The first boundary section 52 and the second boundary section 54 each extend within a range where the amount of deviation in the direction perpendicular to the virtual line L is preferably less than 0.075D, when the diameter of the electrode group 2 is D. In other words, the distance in the direction perpendicular to the virtual line L between the point closest to the virtual line L and the point furthest from the virtual line L at each boundary section, or in other words, the parallelism of each boundary section 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 section be perfectly parallel to the virtual line L, but even if it meanders with respect to the virtual line L, by keeping the amount of deviation in the direction perpendicular to the virtual line L at each boundary section to less than 0.075 times the diameter D, it is possible to suppress the difficulty in achieving uniformity of the bonding area 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 defined, 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, the bonding of the first bonding region 46 and the first current collector plate 20 will be taken as an example to describe the bonding method between the electrode group 2 and the current collector plate. 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 Figure 4(A), in a predetermined region of the electrode group 2, the first processing tool 56 is pressed against the ends of the multiple first electrode plates 6 arranged in the radial direction B, that is, 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 the 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 offset in the circumferential direction of the electrode group 2 with respect to the imaginary line L.

[0032] Furthermore, the second processing tool 60 is pressed against the ends of the multiple first electrode plates 6 arranged in the radial direction B, bending the ends of the multiple 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 multiple first electrode plates 6 with this surface. The second processing tool 60 also presses the area of ​​the electrode group 2 arranged in the circumferential direction with respect to the area pressed by the first processing tool 56 and the imaginary line L. This forms a second ridge line 62 that is substantially parallel to the imaginary line L and offset in the circumferential direction with respect to the first ridge line 58, in other words, aligned with the first ridge line 58 in the circumferential direction with respect to the imaginary line L. The formation of the second ridge line 62 may be simultaneous with the formation of the first ridge line 58, or it may be 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, which are pressed against the ends of each first electrode plate 6, in the radial direction B and in the direction toward the imaginary line L. As an example, in this embodiment, the first processing tool 56 and the second processing tool 60 move toward the winding center C from the outside of the radial direction B, while also moving toward the imaginary line L. In this way, by pressing the first processing tool 56 and the second processing tool 60 against the electrode group 2 and moving them diagonally with respect to the planned formation area of ​​the first bonding region 46, it is possible to easily form the first ridge line 58 and the second ridge line 62 which are parallel to the imaginary line L.

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

[0035] In other words, the displacement of the first workpiece 56 and the second workpiece 60 transitions from a state where the displacement in the radial direction B is greater than the displacement in the direction approaching the virtual line L, to a state where the displacement in the direction approaching the virtual line L is greater than the displacement in the radial direction B. By displacing each workpiece along a curved trajectory, in the initial stages of displacement, the end of the first electrode plate 6 is preferentially bent in the radial direction B, and in the later stages of displacement, the end of each first electrode plate 6 that has bent radially in the B is pressed toward the virtual line L, thereby forming each ridge. This makes it easier to form the first ridge 58 and the second ridge 62 parallel to the virtual line L.

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

[0037] As a result, a roughly rectangular first joining region 46 extending in the radial direction B is formed, as shown in Figure 4(C). The portion pressed and recessed by the first workpiece 56 and the portion pressed and recessed by the second workpiece 60 become the non-joining region 50. Also, the first ridge line 58 becomes the first boundary line 52, and the second ridge line 62 becomes the second boundary line 54.

[0038] In the wound electrode group 2, the first electrode plate 6 located on the outside in the radial direction B is curved with a smaller curvature than the first electrode plate 6 located on the inside in the radial direction B. Therefore, the outer first electrode plate 6 is more prone to bending in the radial direction B than the inner first electrode plate 6. Consequently, when the section 64 is pressed with the third processing tool 66 without providing the first ridge 58 and the second ridge 62, the outer first electrode plate 6 tends to bend at a deeper position than the inner first electrode plate 6, that is, at a position further from the edge in the width direction A. The deeper the bending position, the larger the portion that collapses in the radial direction B. Therefore, the size of the contact area between the first electrode plate 6 and the first current collector plate 20 varies in each wound layer.

[0039] In contrast, when a first ridge 58 and a second ridge 62 are provided that extend substantially parallel to each other, the first electrode plate 6 of each winding layer bends starting from the pair of ridges. This allows for uniformity in 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 aligning the width of the bent portion, uniformity in the depth of the bent portion of each first electrode plate 6 is also achieved. This allows the ends of the first electrode plates 6 located on the outside to bend in the same way as the ends of the first electrode plates 6 located on the inside. Thus, uniformity in the contact area between the first electrode plate 6 and the first current collector plate 20 can be achieved 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, the joining area between the first electrode plate 6 and the first current collector plate 20 in each winding layer can be made uniform.

[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, the joining area between the first electrode plate 6 and the first current collector plate 20 in each winding layer can be made uniform.

[0042] The first ridge line 58 and the second ridge line 62 are preferably formed 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. 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 joining 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 joining 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 is 0.25 times or more 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 is 0.1 times or less 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 joining region 46, it becomes difficult to make the joining area between the first electrode plate 6 and the first current collector plate 20 in each winding layer uniform.

[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] Similar 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) in 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. Thus, the quality of the battery 1 can be improved.

[0049] Further, the first boundary portion 52 and the second boundary portion 54 of the present embodiment extend in 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. Further, the bonding region extends to the outer edge in the radial direction B of the electrode group 2. By these, 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] Also, 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 shifted 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 shifted 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 of the bending of the electrode plates in each winding layer, each electrode plate can be bent more uniformly. Thereby, the joint area between the electrode plate 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] Moreover, the joining method of the present embodiment includes displacing the first tool 56 and the second tool 60 in the radial direction B and 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, 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 plate and the current collector plate in each winding layer more uniform.

[0053] Moreover, the joining method of the present embodiment includes forming the first ridge line 58 and the second ridge line 62 so as to extend in a range where the amount of deviation in the direction orthogonal to the virtual line L is less than 0.075D. Further, the joining method of the present embodiment 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, the joining method of the present embodiment 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, it becomes easier to make the joint area between the electrode plate and the current collector plate in each winding layer more uniform.

[0054] The embodiments of this disclosure have been described in detail above. The embodiments described above are merely examples of how to implement this disclosure. The content of the embodiments does not limit the technical scope of this disclosure, and many design changes, such as changes, additions, and deletions of components, are possible as long as they do not depart from the spirit of the invention as defined in the claims. A new embodiment with design changes will have the combined effects of both the embodiment and the variation. In the embodiments described above, the content in which such design changes are possible is emphasized with notations such as "of this embodiment" or "in this embodiment," but design changes are also permitted even if there are no such notations. Furthermore, any combination of components included in each embodiment is also valid as an embodiment of this disclosure. The hatching applied to the cross-section in the drawings does not limit the material of the object to which the hatching is applied.

[0055] The embodiments may be specified by the items described below. [1st item] A wound electrode group (2) is formed by stacking and winding a separator (10) and electrode plates (6,8), Equipped with current collector plates (20, 22), The electrode group (2) has multiple electrode plates (6,8) arranged in the radial direction (B), the ends of which are bent in the radial direction (B), and the bent ends are joined to the current collector plates (20,22) in a joining region (46,48). The junction region (46,48) is sandwiched between two non-junction regions (50) arranged circumferentially around the electrode group (2). The first boundary (52), which is the boundary between the junction region (46,48) and one of the non-junction regions (50), and the second boundary (54), which is the boundary between the junction region (46,48) and the other non-junction region (50), each extend substantially parallel to a predetermined imaginary line (L) passing through the winding center (C) of the electrode group (2) and the junction region (46,48). Batteries (1). [Second item] The first boundary (52) and the second boundary (54) extend within a range where the displacement in the direction perpendicular to the imaginary line (L) is less than 0.075D, when the diameter of the electrode group (2) is D. The battery (1) according to Item 1. [Item 3] When the interval 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 interval M satisfies 0.1D < M < 0.25D. The battery (1) according to Item 1 or Item 2. [Item 4] The bonding 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 method of joining 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 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 (6, 8) in the section (64) in the radial direction (B) to form bonding regions (46, 48), including joining the plurality of bent ends in the bonding regions (46, 48) and the current collector plates (20, 22). Joining method. [Item 6] including displacing the first tool (56) and the second tool (60) in the radial direction (B) and in 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 bonding 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 bonding 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 bonding 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 bonding 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 bonding 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 bonding region, 48 Second bonding region, 50 Non-bonding region, 52 First boundary portion, 54 Second boundary portion, 56 First tool, 58 First ridge line, 60 Second tool, 62 Second ridge line, 64 Section, 66 Third tool.

Claims

1. A wound-type electrode group in which separators and electrode plates are stacked and wound, Equipped with a current collector plate, The electrode group has a bonding region in which the ends of a plurality of electrode plates arranged in the radial direction are bent in the radial direction, and the bent plurality of ends are joined to the current collector plate. The bonding region is sandwiched between two non-bonding regions arranged circumferentially around the electrode group, and the first boundary portion, which is the boundary between the bonding region and one of the non-bonding regions, and the second boundary portion, which is the boundary between the bonding region and the other non-bonding region, each extend substantially parallel to a predetermined imaginary line passing through the winding center of the electrode group and the bonding region. battery.

2. The first boundary and the second boundary each extend within a range where the displacement in the direction perpendicular to the imaginary line is less than 0.075D, when the diameter of the electrode group is D. The battery according to claim 1.

3. When the distance between the first boundary and the second boundary at each of the radial positions is M, and the diameter of the electrode group is D, the distance M satisfies 0.1D < M < 0.25D. The battery according to claim 1 or 2.

4. The bonding region extends to the radial outer edge of the electrode group. The battery according to claim 1 or 2.

Images