Storage battery unit
By incorporating grooves and multiple extensions at the bends of the tab leads, the problem of increased stress in large-scale battery cells was solved, resulting in reduced tab lead resistance and improved performance.
Patent Information
- Application Number
- CN202422789061.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Priority Date
- 2023-12-11
- Filing Date
- 2024-11-15
- Publication Date
- 2025-11-04
- Estimated Expiration
- 2034-11-15
AI Technical Summary
In large-scale storage battery cells, the increased current in the tab leads leads to increased resistance, and the stress in the bent parts also increases. Existing technologies cannot effectively reduce the stress in the tab leads.
The design of the tab lead has a groove in the bent part, which extends in the winding direction and dissipates heat through multiple extensions. The roots of the bent part and the extensions are not aligned with the groove in the axial direction, and the multiple extensions are separated from each other in the winding direction, making it easier to adjust the extension direction when bending.
This reduces the stress on the tab leads, decreases their resistance, and improves the performance and reliability of the battery cell.
Smart Images
Figure CN223514190U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to a storage battery unit. Background Technology
[0002] Japanese Patent No. 3203517 discloses a conventional rechargeable battery unit. This battery includes a wound electrode body, a first electrode lead, and a battery can housing the wound electrode body. The first electrode lead is configured to engage with a first strip electrode at its wound end on the outer periphery of the wound electrode body. The second electrode lead is configured to engage with a second strip electrode at its wound end on the inner periphery of the wound electrode body. Utility Model Content
[0003] In recent years, there has been a desire to increase the size of battery cells. If battery cells are enlarged, the current flowing through the wound electrode body increases. Therefore, it has been considered to lengthen the tab leads (electrode leads) in the winding direction of the wound electrode body. This would ideally reduce the resistance of the tab leads. However, by lengthening the tab leads, the stress applied to the portion of the tab leads that bends along the winding direction of the wound electrode body also increases.
[0004] This invention was made in view of the above-mentioned problems, and its purpose is to provide a battery cell that can reduce the stress on the tab leads.
[0005] One aspect of this utility model relates to a storage battery cell comprising a wound electrode body and a battery cell housing accommodating the wound electrode body. The wound electrode body includes an electrode plate and tab leads. The electrode plate has a current-collecting foil and an electrode material layer. The electrode material layer is coated on a portion of the current-collecting foil. The tab leads include a bent portion and an extended portion. The bent portion is disposed on an uncoated portion of the current-collecting foil where the electrode material layer is not coated, and extends in a bent manner along the winding direction of the wound electrode body. The extended portion extends out from the bent portion and extends towards one side of the current-collecting foil in the axial direction of the wound electrode body. The bent portion has a groove extending along the aforementioned axial direction.
[0006] Based on the above structure, the bent portion can be easily bent at the groove. Therefore, even if the tab lead is lengthened in the winding direction, the bent portion can extend in a direction closer to the winding direction. Furthermore, the stress on the tab lead can be reduced.
[0007] In one embodiment of the present invention, the battery cell preferably has a plurality of grooves arranged in the aforementioned winding direction.
[0008] According to the above structure, the bent portion can extend in a direction closer to the winding direction. Furthermore, this can further reduce the stress on the tab lead.
[0009] In one embodiment of the present invention, the battery cell preferably has a root portion. The root portion is the part where the extension portion connects to the curved portion. The root portion is configured not to be aligned with the groove portion in the aforementioned axial direction.
[0010] According to the above structure, it is possible to prevent the extended portion from bending in an undesirable manner along with the bending of the curved portion at the groove.
[0011] In one embodiment of the present invention, the battery cell preferably has a plurality of extensions arranged in the aforementioned winding direction. Each of the plurality of extensions has a root portion, which is the portion where each extension portion connects to the bend portion. The root portions of each of the plurality of extensions are configured not to be aligned with the groove portion in the aforementioned axial direction.
[0012] According to the above structure, by providing multiple extensions, the heat-generating parts of the electrode lead can be dispersed. Furthermore, by arranging multiple extensions as described above, it is possible to prevent the multiple extensions from bending in an undesirable manner.
[0013] In one embodiment of the rechargeable battery cell according to this utility model, preferably, the tab leads have a plurality of extensions arranged in the aforementioned winding direction. Each of the plurality of extensions has a root portion, which is the portion where each of the plurality of extensions connects to the bend portion. The roots of each of the plurality of extensions are configured not to be arranged with any of the plurality of groove portions in the aforementioned axial direction. The roots of each of the plurality of extensions are separated from each other in the aforementioned winding direction.
[0014] According to the above structure, by providing multiple extensions, the heat-generating parts of the tab lead can be dispersed. By arranging multiple extensions as described above, it is possible to prevent the multiple extensions from bending in an undesirable manner. Moreover, by separating the roots from each other, the multiple extensions can easily bend towards the radial center at their roots. Therefore, the extension direction of the multiple extensions can be easily adjusted.
[0015] According to this invention, the stress on the electrode leads can be reduced. Attached Figure Description
[0016] Hereinafter, with reference to the accompanying drawings, the features, advantages, and technical and industrial significance of exemplary embodiments of the present invention will be described, in which the same reference numerals denote the same elements, and wherein:
[0017] Figure 1 This is a cross-sectional view showing the storage battery unit involved in the embodiment of this utility model.
[0018] Figure 2 This is a schematic top view of a portion of the wound electrode body viewed from one side along its axial direction.
[0019] Figure 3 This is a schematic diagram showing the positive electrode plate and positive electrode tab leads in a state where the coil has been unwound and extended into a planar shape.
[0020] Figure 4 This is a schematic top view of a portion of the wound electrode body viewed from the opposite side along the axial direction of the wound electrode body.
[0021] Figure 5 This is a schematic diagram showing the negative electrode plate and negative electrode tab leads in a state where the winding has been unwound and extended into a planar shape. Detailed Implementation
[0022] The embodiments of this utility model will now be described in detail with reference to the accompanying drawings. Furthermore, identical or corresponding parts in the drawings will be labeled with the same symbols, and their descriptions will not be repeated.
[0023] The battery cell described below, as an embodiment of the present invention, is, for example, a lithium-ion battery mounted in a vehicle. However, the uses and types of battery cells are not limited to the example described above.
[0024] Figure 1 This is a cross-sectional view showing the storage battery unit involved in the embodiment of this utility model. Figure 1 The diagram shows the overall structure of the storage battery unit 1 according to one embodiment of the present invention.
[0025] like Figure 1 As shown, the storage battery unit 1 includes a wound electrode body 100 and a battery unit housing 200.
[0026] The wound electrode body 100 includes a positive electrode plate 110, a negative electrode plate 120, a separator 130, a positive electrode tab lead 140, and a negative electrode tab lead 150. The wound electrode body 100 is configured to include an electrode plate assembly, which is formed by winding the positive electrode plate 110 and the negative electrode plate 120 through the separator 130.
[0027] Figure 2 This is a schematic top view of a portion of the wound electrode body viewed from one side along its axial direction. Figure 3 This is a schematic diagram showing the positive electrode plate and positive electrode tab leads in a state where the coil has been unwound and extended into a planar shape.
[0028] like Figure 2 and Figure 3 As shown, the positive electrode plate 110 has a positive electrode current collector foil 111 and a positive electrode material layer 112. The positive electrode material layer 112 is coated on a portion of the positive electrode current collector foil 111.
[0029] The positive electrode current collector foil 111 has an uncoated portion 111a and a coated portion 111b. The uncoated portion 111a is the part of the positive electrode current collector foil 111 that is not coated with the positive electrode material layer 112. The coated portion 111b is the part of the positive electrode current collector foil 111 that is coated with the positive electrode material layer 112.
[0030] In this embodiment, the uncoated portion 111a is provided at the respective ends of the positive electrode plate 110 on both the X1 and X2 sides. The X1 side is the winding end side in the winding direction X of the winding electrode body 100. The X2 side is the winding start side in the winding direction X. That is, the X1 side is the outer peripheral side of the radial direction R of the winding electrode body 100, and the X2 side is the center side of the radial direction R of the winding electrode body 100.
[0031] In this embodiment, the positive electrode plate 110 is configured such that one coating portion 111b is continuous in the winding direction X. That is, the positive electrode plate 110 is configured such that one positive electrode material layer 112 is continuous in the winding direction X. However, it is also possible to configure multiple coating portions 111b to be separated in the winding direction X. That is, it is also possible to configure multiple positive electrode material layers 112 to be separated in the winding direction X. Uncoated portions 111a can be disposed between multiple coating portions 111b in the winding direction X.
[0032] The positive electrode current collector foil 111 is, for example, made of aluminum. The positive electrode material layer 112 is formed by coating a positive electrode slurry onto the surface of the positive electrode current collector foil 111 and then drying it. The positive electrode slurry is a slurry that is adjusted by mixing positive electrode active materials, binders, and solvents. The positive electrode material layer 112 is in close contact with the separator 130. The thickness of the positive electrode material layer 112 is, for example, 0.1 μm or more and 1000 μm or less.
[0033] In addition, the positive electrode plate 110, the positive electrode current collector foil 111, and the positive electrode material layer 112 can be examples of the "electrode plate", "current collector foil", and "electrode material layer" of this utility model, respectively.
[0034] Figure 4 This is a schematic top view of a portion of the wound electrode body viewed from the opposite side along the axial direction of the wound electrode body. Figure 5 This is a schematic diagram showing the negative electrode plate and negative electrode tab leads in a state where the winding has been unwound and extended into a planar shape.
[0035] like Figure 4 and Figure 5 As shown, the negative electrode plate 120 has a negative electrode current collector foil 121 and a negative electrode material layer 122. The negative electrode material layer 122 is coated on a portion of the negative electrode current collector foil 121.
[0036] The negative electrode current collector foil 121 has an uncoated portion 121a and a coated portion 121b. The uncoated portion 121a is the part of the negative electrode current collector foil 121 that is not coated with the negative electrode material layer 122. The coated portion 121b is the part of the negative electrode current collector foil 121 that is coated with the negative electrode material layer 122.
[0037] In this embodiment, the uncoated portion 121a is provided at the ends of the X1 side and X2 side of the negative electrode plate 120.
[0038] In this embodiment, the negative electrode plate 120 is configured such that one coating portion 121b is continuous in the winding direction X. That is, the negative electrode plate 120 is configured such that one negative electrode material layer 122 is continuous in the winding direction X. However, it is also possible to configure multiple coating portions 121b to be separated in the winding direction X. That is, it is also possible to configure multiple negative electrode material layers 122 to be separated in the winding direction X. Uncoated portions 121a can be disposed between multiple coating portions 121b in the winding direction X.
[0039] The negative electrode current collector foil 121 is, for example, made of copper. The negative electrode material layer 122 is formed by coating a negative electrode slurry onto the surface of the negative electrode current collector foil 121 and allowing it to dry. The negative electrode slurry is a slurry that is adjusted by mixing negative electrode active materials, binders, and solvents. The negative electrode material layer 122 is in close contact with the separator 130. The thickness of the negative electrode material layer 122 is, for example, 0.1 μm or more and 1000 μm or less.
[0040] In addition, the negative electrode plate 120, the negative electrode current collector foil 121 and the negative electrode material layer 122 can be another example of the "electrode plate", "current collector foil" and "electrode material layer" of this utility model.
[0041] like Figure 1 , Figure 2 and Figure 4 As shown, a separator 130 is disposed between the positive electrode plate 110 and the negative electrode plate 120. The separator 130 enables ions (e.g., lithium ions) to travel back and forth between the positive electrode material layer 112 of the positive electrode plate 110 and the negative electrode material layer 122 of the negative electrode plate 120, and separates the positive electrode plate 110 and the negative electrode plate 120.
[0042] like Figures 1 to 3 As shown, the positive electrode tab lead 140 is configured to protrude from the positive electrode current collector foil 111 of the positive electrode plate 110 toward one side (Z1 side) in the Z-axis direction. The positive electrode tab lead 140 includes a bent portion 141 and an extended portion 142.
[0043] A bent portion 141 is provided on the uncoated portion 111a. The bent portion 141 is provided on the uncoated portion 111a at the end of the positive electrode plate 110 located on the X1 side. However, the bent portion 141 may also be provided on the uncoated portion 111a at the end of the positive electrode plate 110 located on the X2 side. The bent portion 141 may also be provided on such an uncoated portion 111a when the uncoated portion 111a is not located at the end of the positive electrode plate 110 in the winding direction X. The bent portion 141 extends in a manner that bends along the winding direction X of the winding electrode body 100.
[0044] In this embodiment, the bent portion 141 extends along the axial direction Z of the wound electrode body 100 toward one side (Z1 side) of the positive electrode current collector foil 111. As a result, the extended portion 142 can be easily bent at its root 142a. In addition, the bent portion 141 can be entirely provided on the uncoated portion 111a.
[0045] The bent portion 141 has a groove 141S. The groove 141S extends along the axial direction Z. The bent portion 141 has a plurality of grooves 141S. The plurality of grooves 141S are arranged in the winding direction X. The plurality of grooves 141S are arranged at approximately equal intervals in the winding direction X. Each groove 141S extends from one end edge of the bent portion 141 in the axial direction Z to the other end edge. Each groove 141S extends in a straight line along the axial direction Z.
[0046] The extension portion 142 extends out from the bending portion 141. The bending portion 141 extends in the axial direction Z of the winding electrode body 100 toward one side (Z1 side) of the positive electrode current collector foil 111.
[0047] The extension 142 has a root 142a. The root 142a is the portion that connects to the bend 141. The root 142a is configured not to be aligned with the groove 141S in the axial direction Z.
[0048] The extension 142 bends at the root 142a. The extension 142 bends toward the center side of the radial R of the coiled electrode body 100.
[0049] The positive electrode lead 140 has a plurality of extensions 142. The plurality of extensions 142 are arranged in the winding direction X. Each of the plurality of extensions 142 has a root portion 142a, which is the portion connected to the bend portion 141. The root portions 142a of each of the plurality of extensions 142 are configured not to be aligned with the slot portions 141S in the axial direction Z. Specifically, each root portion 142a is configured not to be aligned with any of the plurality of slot portions 141S in the axial direction Z. The root portions 142a of each of the plurality of extensions 142 are separated from each other in the winding direction X.
[0050] Multiple extensions 142 are bent at their respective roots 142a. The multiple extensions 142 are bent toward the center of the radial direction R around the electrode body 100. When viewed from the axial direction Z, the multiple extensions 142 overlap each other. The multiple extensions 142 can be fused together.
[0051] like Figure 1 , Figure 4 and Figure 5 As shown, the negative electrode tab lead 150 is configured to protrude from the negative electrode current collector foil 121 of the negative electrode plate 120 to the other side (Z2 side) in the Z-axis direction. The negative electrode tab lead 150 includes a bent portion 151 and an extended portion 152.
[0052] A bent portion 151 is provided on the uncoated portion 111a. The bent portion 151 is provided on the uncoated portion 121a at the end of the negative electrode plate 120 located on the X2 side. However, the bent portion 151 may also be provided on the uncoated portion 121a at the end of the negative electrode plate 120 located on the X1 side. The bent portion 151 may also be provided on such an uncoated portion 121a when the uncoated portion 121a is not located at the end of the negative electrode plate 120 in the winding direction X. The bent portion 151 extends in a bent manner along the winding direction X.
[0053] In this embodiment, the bent portion 151 extends along the axial direction Z of the wound electrode body 100 toward the other side (Z2 side) of the negative electrode current collector foil 121. Therefore, the extended portion 152 can be easily bent at its root 152a. Furthermore, the bent portion 151 can be entirely disposed on the uncoated portion 111a.
[0054] The bent portion 151 has a groove 151S. The groove 151S extends along the axial direction Z. The bent portion 151 has a plurality of grooves 151S. The plurality of grooves 151S are arranged in the winding direction X. The plurality of grooves 151S are arranged at approximately equal intervals in the winding direction X. Each groove 151S extends from one end edge of the bent portion 151 in the axial direction Z to the other end edge. Each groove 151S extends in a straight line along the axial direction Z.
[0055] The extension portion 152 extends out from the bending portion 151. The extension portion 152 extends in the axial direction Z of the winding electrode body 100 toward the other side (Z2 side) of the negative electrode current collector foil 121.
[0056] The extension 152 has a root 152a. The root 152a is the portion that connects to the bend 151. The root 152a is configured not to be aligned with the groove 151S in the axial direction Z.
[0057] The extension 152 is bent at the root 152a. The extension 152 is bent toward the center side of the radial R of the winding electrode body 100.
[0058] The negative electrode tab lead 150 has a plurality of extensions 152. The plurality of extensions 152 are arranged in the winding direction X. Each of the plurality of extensions 152 has a root portion 152a, which is the portion connected to the bend portion 151. The root portions 152a of each of the plurality of extensions 152 are configured not to be aligned with the slot portions 151S in the axial direction Z. Specifically, each root portion 152a is configured not to be aligned with any one of the plurality of slot portions 151S in the axial direction Z. The root portions 152a of each of the plurality of extensions 152 are separated from each other in the winding direction X.
[0059] Multiple extensions 152 are bent at their respective roots 152a. The multiple extensions 152 are bent toward the center of the radial direction R around the electrode body 100. When viewed from the axial direction Z, the multiple extensions 152 overlap each other. The multiple extensions 152 can be welded together.
[0060] like Figure 1 As shown, the battery cell housing 200 houses the wound electrode body 100. The battery cell housing 200 has a cylindrical shape. Therefore, the storage battery cell 1 is a cylindrical battery.
[0061] The battery cell housing 200 has an outer peripheral wall portion 210, a first end portion 220 and a second end portion 230.
[0062] The outer peripheral wall portion 210 is cylindrical and is disposed on the outer side of the radial direction R of the wound electrode body 100. The outer peripheral wall portion 210 is formed of copper or aluminum, etc. The outer peripheral wall portion 210 is in contact with the negative electrode current collector of the negative electrode plate 120 disposed on the outermost periphery of the wound electrode body 100.
[0063] The first end portion 220 is connected to one side (Z1 side) of the outer peripheral wall portion 210 in the axial direction Z of the wound electrode body 100.
[0064] Specifically, the first end 220 has an outer cover 222, an insulating layer 223, and a riveting portion 224.
[0065] The outer cover 222 functions as an external terminal through electrical connection with an external busbar (not shown). A vulnerable portion 225 (thin-walled portion) is provided on the outer cover 222. In the event of an increase in internal pressure within the battery cell housing 200, the outer cover 222 is prone to rupture, starting from the vulnerable portion 225. This allows gas to rapidly escape to the outside of the battery cell housing 200. The outer cover 222 is formed of copper or aluminum, etc.
[0066] The insulating layer 223 is configured to cover the outer peripheral end of the outer cover 222. The insulating layer 223 is configured to insulate the outer cover 222 from the riveting portion 224.
[0067] The riveting portion 224 is connected to one side of the outer peripheral wall portion 210 along the axial Z direction of the wound electrode body 100. The riveting portion 224 is integrally formed with the outer peripheral wall portion 210. The riveting portion 224 is riveted to the outer periphery of the outer cover 222 (and the conductive film 510 described later) through the insulating layer 223. The riveting portion 224 is formed of copper or aluminum, etc.
[0068] The second end portion 230 is connected to the other side (Z2 side) of the outer peripheral wall portion 210 in the Z direction. The second end portion 230 has a circular plate-like shape. The second end portion 230 is formed of copper or aluminum, etc. The periphery of the second end portion 230 is connected to the outer peripheral wall portion 210. The second end portion 230 and the outer peripheral wall portion 210 are integrally formed.
[0069] The second end 230 comes into contact with the negative electrode lead 150. Thus, the negative electrode lead 150 is electrically connected to the second end 230. As a result, the second end 230, the outer peripheral wall portion 210 connected to the second end 230, and the riveting portion 224 are all negatively charged.
[0070] The battery cell 1 also includes a positive side insulation plate 300, a negative side insulation plate 400, and a CID (Current Interrupt Device) 500.
[0071] The positive insulating plate 300 is housed within the battery cell housing 200. The positive insulating plate 300 is configured to insulate the wound electrode body 100 (negative electrode plate 120 and separator 130) from the battery cell housing 200. The positive insulating plate 300 is configured to cover the positive electrode plate 110, negative electrode plate 120 and separator 130 from one side (Z1 side).
[0072] The positive insulating plate 300 has a first through hole 310. The extension 142 of the positive electrode tab lead 140 is inserted into the first through hole 310, thereby contacting the conductive film 510 described later. Thus, the positive electrode tab lead 140 is electrically connected to the conductive film 510.
[0073] The negative-side insulating plate 400 is housed within the battery cell housing 200. The negative-side insulating plate 400 is configured to insulate the wound electrode body 100 (positive electrode plate 110 and separator 130) from the battery cell housing 200. The negative-side insulating plate 400 is configured to cover the positive electrode plate 110, negative electrode plate 120, and separator 130 from the other side (Z2 side).
[0074] The negative side insulating plate 400 has a second through hole 410. The extension 152 of the negative electrode tab lead 150 is inserted into the second through hole 410. Thus, the extension 152 of the negative electrode tab lead 150 is electrically connected to the second end 230.
[0075] CID500 is a component that cuts off the current path by utilizing the increase in internal pressure of the battery cell caused by the gas generated due to overcharging of the battery cell 1. CID500 is configured to close the opening on one side (Z1 side) of the outer peripheral wall portion 210. CID500 has a conductive film 510, a gasket 520, and a chassis 530.
[0076] The conductive film 510 is configured to close the opening on one side (Z1 side) of the outer peripheral wall portion 210. The conductive film 510 is in contact with the extension portion 142 of the positive electrode tab lead 140. As a result, the conductive film 510 is positively charged. Furthermore, the conductive film 510 is electrically connected to the outer cover 222 via a connecting member (not shown). As a result, the outer cover 222 is also positively charged.
[0077] Specifically, the conductive film 510 includes a protrusion 511 that protrudes toward the side of the wound electrode body 100 (Z2 side). The protrusion 511 contacts the extension 142 of the positive electrode tab lead 140.
[0078] Similar to the outer cover 222, a vulnerable portion 512 (thin-walled portion) is provided on the conductive film 510. When the internal pressure of the battery cell housing 200 increases, the conductive film 510 is prone to rupture starting from the vulnerable portion 512. When the conductive film 510 ruptures due to the increased internal pressure, the contact between the conductive film 510 and the extension 142 of the positive electrode lead 140 is released. As a result, the positive charge on the conductive film 510 is eliminated, and the positive charge on the outer cover 222 is also eliminated. Consequently, the charging and discharging of the battery cell 1 stops.
[0079] The washer 520 is located on the side of the wound electrode body 100 of the conductive film 510. The chassis 530 is connected to the conductive film 510 through the washer 520. The protrusion 511 of the conductive film 510 passes through the washer 520 and the chassis 530.
[0080] As described above, in the positive electrode tab lead 140 of the battery cell 1 according to the embodiment of this utility model, the bending portion 141 has a groove 141S. Therefore, the bending portion 141 is easily bent at the groove 141S. Thus, even if the positive electrode tab lead 140 is extended in the winding direction X, the bending portion 141 can extend in a direction closer to the winding direction X. Furthermore, the stress on the positive electrode tab lead 140 can be reduced.
[0081] Furthermore, in the negative electrode tab lead 150, the bent portion 151 also has a groove 151S. Therefore, the bent portion 151 is easily bent at the groove 151S. Thus, even if the negative electrode tab lead 150 is extended in the winding direction X, the bent portion 151 can extend in a direction closer to the winding direction X. Furthermore, the stress on the negative electrode tab lead 150 can be reduced.
[0082] It should be considered that the embodiments disclosed herein are illustrative in all respects and not restrictive. The scope of this utility model is set forth not by the description of the above embodiments but by the claims, and is intended to include all modifications within the meaning and scope equivalent to the claims.
Claims
1. A storage battery unit, characterized in that, have: Winded electrode body; and A battery cell housing that houses the wound electrode body. The wound electrode body includes an electrode plate and electrode leads. The electrode plate has a current-collecting foil and an electrode material layer coated on a portion of the current-collecting foil. The electrode lead includes: A bent portion is disposed on an uncoated portion of the current collector foil where the electrode material layer is not coated, and extends in a bent manner along the winding direction of the wound electrode body; and An extension portion extends from the curved portion and extends axially toward one side of the current collector foil on the wound electrode body. The curved portion has a groove extending along the axial direction.
2. The storage battery unit according to claim 1, characterized in that, The curved portion has a plurality of grooves arranged in the winding direction.
3. The storage battery unit according to claim 1, characterized in that, The extended portion has a root portion, which is the part where the extended portion connects to the curved portion. The root portion is configured not to be aligned with the groove portion in the axial direction.
4. The storage battery unit according to claim 1, characterized in that, The electrode lead has a plurality of extensions arranged in the winding direction. Each of the plurality of extended portions has a root portion, which is the portion where each of the plurality of extended portions connects to the curved portion. The root of each of the plurality of extensions is configured not to be aligned with the groove in the axial direction.
5. The storage battery unit according to claim 2, characterized in that, The electrode lead has a plurality of extensions arranged in the winding direction. Each of the plurality of extended portions has a root portion, which is the portion where each of the plurality of extended portions connects to the curved portion. The root of each of the plurality of extensions is configured such that it is not aligned with any of the plurality of grooves in the axial direction. The roots of each of the plurality of extensions are separated from each other in the winding direction.