Method for manufacturing cylindrical batteries and energy storage cells
The battery cell design addresses the challenge of maintaining conductivity and reducing dimensions in the uncoated portion of the current collector foil by employing bent and folded regions, thereby improving energy density and reducing electrical resistance.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Patents
- Current Assignee / Owner
- TOYOTA JIDOSHA KK
- Filing Date
- 2023-05-26
- Publication Date
- 2026-06-02
Smart Images
Figure 0007868555000001 
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Abstract
Description
Technical Field
[0001] This disclosure relates to a storage battery cell.
Background Art
[0002] U.S. Patent Application Publication No. 2020 / 0144676 (Patent Document 1) discloses a cell having at least one tabless electrode. The contact surface of the first cap corresponds to the conductive portion of the rolled first substrate and is configured to be connected. The conductive portion is an exposed area of the first substrate.
Prior Art Documents
Patent Documents
[0003]
Patent Document 1
Summary of the Invention
Problems to be Solved by the Invention
[0004] Regarding a so-called tabless-structured battery such as Patent Document 1 above, in order to improve the energy density, it is preferable to reduce the dimensions of the end portion (uncoated portion) of the current collector foil in the axial direction of the wound electrode body. Here, in order to reduce the axial dimension of the uncoated portion, it is also conceivable to make the uncoated portion into a complex shape by making a plurality of cuts. However, if the uncoated portion has a complex shape, the degree of freedom of the current conduction path of the current collector foil may decrease. When the degree of freedom of the current collector foil conduction path decreases, the amount of heat generated due to the electrical resistance of the current collector foil may increase.
[0005] This disclosure has been made in view of the above problems, and an object thereof is to provide a storage battery cell that can suppress a decrease in the degree of freedom of the current conduction path of the current collector foil while reducing the dimension of the uncoated portion in one direction.
Means for Solving the Problems
[0006] A storage cell according to the first aspect of the present disclosure comprises a wound electrode body including a first electrode and a second electrode, and a case for housing the wound electrode body. The first electrode includes a current collector foil and an electrode material coated on a portion of the current collector foil. The current collector foil has a coated portion on which the electrode material is provided, and an uncoated portion on which the electrode material is not provided, exposed on one side in the axial direction of the wound electrode body, and extending in the winding direction of the wound electrode body. The uncoated portion has a plurality of bent portions bent radially toward the wound electrode body, and a folded portion formed by folding regions located between a plurality of adjacent bent portions.
[0007] According to the above configuration, since the uncoated portion is bent radially, the dimensions of the uncoated portion in the axial direction of the wound electrode body can be reduced. At the same time, the regions between the bent portions in the uncoated portion are folded, so that the bent portions are reliably electrically connected to each other by the folded portions. Therefore, a reduction in the degree of freedom of the conductive path in the current collector foil can be suppressed.
[0008] In the energy storage cell relating to the first aspect of this disclosure, preferably, the radial length of each of the multiple bent portions is 1 mm or more and 23 mm or less.
[0009] Having a radial length of 1 mm or more in the bent portion results in a relatively large area of the bent portion when viewed from the axial direction, making it easier to connect the bent portion to other components such as current collector plates. At the same time, having a radial length of 23 mm or less in the bent portion results in a relatively small size of the folded portion. Therefore, the average thickness of the portion consisting of the bent and folded portions within the unpainted area can be reduced. Consequently, the dimensions of the unpainted portion in the axial direction of the wound electrode body can be further reduced.
[0010] In the energy storage cell relating to the first aspect of this disclosure, preferably, the winding length of each of the multiple bent portions is 1 mm or more and 40 mm or less.
[0011] By having a winding length of 1 mm or more in the bent portion, the reduction in the degree of freedom of the conductive path in the current collector foil can be further suppressed. At the same time, by having a winding length of 40 mm or less in the bent portion, the deflection of the bent portion is suppressed. Consequently, the dimensions of the uncoated portion in the axial direction can be made smaller.
[0012] A storage cell according to a second aspect of the present disclosure comprises a current collector foil and an electrode material coated on a portion of the current collector foil. The length of the current collector foil in a first direction is longer than the length in a second direction intersecting the first direction. The current collector foil has a coated portion on which the electrode material is provided and an uncoated portion on which the electrode material is not provided and which extends from the coated portion in a second direction. The uncoated portion has a first fold and a second fold. The first fold and the second fold are formed such that the distance between the first fold and the second fold increases as the distance from the coated portion increases in the second direction.
[0013] According to the above configuration, by folding the first and second folds of the unpainted portion while winding the current collector foil, the unpainted portion can be easily folded in the radial direction relative to the winding direction. By folding the unpainted portion in the radial direction, the dimensions of the unpainted portion in the second direction can be reduced. In addition, by folding the first and second folds, the region between the first and second folds can be folded. This maintains a continuous state of the unpainted portion in the first direction. Therefore, a decrease in the degree of freedom of the conductive path in the current collector foil can be suppressed.
[0014] In the energy storage cell relating to the second aspect of this disclosure, preferably, the coated end of the first fold and the coated end of the second fold coincide with each other.
[0015] According to the above configuration, between the first fold and the second fold The unpainted area The area of the folded portion formed by folding can be reduced. Consequently, the average thickness of the folded portion of the uncoated area in the second direction can be reduced.
[0016] In the energy storage cell relating to the second aspect of the present disclosure, preferably, the uncoated portion further has a third fold. The third fold is formed on the side opposite to the second fold when viewed from the first fold.
[0017] According to the above configuration, when folding the first and second folds, the third fold is also made, allowing the uncoated portion to be folded radially to form the folded portion. After this, the third fold is bent back to form the folded portion. Consequently, the folded portion and the folded portion can be easily formed.
[0018] A power storage cell according to a third aspect of the present disclosure comprises a current collector foil and an electrode material coated on a portion of the current collector foil. The length of the current collector foil in a first direction is longer than the length in a second direction intersecting the first direction. The current collector foil has a coated portion on which the electrode material is provided and an uncoated portion on which the electrode material is not provided and which extends from the coated portion in a second direction. The uncoated portion includes a base and an extension. The base is connected to the coated portion in the second direction. The extension extends from the base on the side opposite to the coated portion. The length of the extension in the first direction is 73 mm or more and shorter than the length of the base in the first direction.
[0019] With the above configuration, since the length of the extension in the first direction is shorter than the length of the base in the first direction, the extension can be easily bent relative to the base. Therefore, the dimensions of the uncoated portion in the second direction can be reduced. In addition, since the length of the extension in the first direction is 73 mm or more, it is possible to prevent the extension from becoming too small, and thus prevent a decrease in the degree of freedom of the conductive path in the current collector foil.
[0020] In the energy storage cell relating to the third aspect of this disclosure, preferably, the length of the extension in the first direction is 220 mm or less.
[0021] With the above configuration, the length of the extension in the first direction is 220 mm or less, which makes it easier to bend the extension.
[0022] In the power storage cell according to the third aspect of the present disclosure, preferably, the length of the extension portion in the second direction is 1 mm or more and 23 mm or less.
[0023] According to the above configuration, since the length of the extension portion in the second direction is 1 mm or more, the extension portion can be more easily bent with respect to the base portion. At the same time, since the length of the extension portion in the second direction is 23 mm or less, the dimension of the uncoated portion in the second direction can be made smaller.
Effect of the Invention
[0024] According to the present disclosure, it is possible to suppress a decrease in the degree of freedom of the current collecting foil's conduction path while reducing the dimension of the uncoated portion in one direction.
Brief Description of the Drawings
[0025] [Figure 1] It is a cross-sectional view showing the entire power storage cell according to an embodiment of the present disclosure. [Figure 2] In the power storage cell according to an embodiment of the present disclosure, it is a partial cross-sectional view showing an enlarged upper surface portion of the case and its peripheral portion. [Figure 3] In the power storage cell according to an embodiment of the present disclosure, it is a partial cross-sectional view showing an enlarged lower surface portion of the case and its peripheral portion. [Figure 4] In the power storage cell according to an embodiment of the present disclosure, it is a schematic plan view showing a state where the wound positive electrode plate is extended in a planar shape. [Figure 5] When manufacturing the wound electrode body, it is a schematic perspective view showing a state immediately after the positive electrode plate, the negative electrode plate, and the separator laminated on each other are wound together. [Figure 6] When manufacturing the wound electrode body, it is a schematic cross-sectional view showing a state immediately after the positive electrode plate, the negative electrode plate, and the separator are wound together. [Figure 7] It is a schematic plan view showing a state immediately before a plurality of blades are pressed against the extension portion of the positive electrode uncoated portion in the state immediately after winding. [Figure 8]This is a schematic plan view showing the state immediately after winding, where multiple blades are pressed radially against the uncoated extension of the positive electrode. [Figure 9] This is a schematic top view showing a wound electrode body according to one embodiment of the present disclosure. [Figure 10] This is a schematic perspective view showing a wound electrode body according to one embodiment of the present disclosure, viewed from above. [Figure 11] This is a schematic plan view showing a state in which a wound negative electrode plate is flattened in a planar manner in a storage cell according to one embodiment of the present disclosure. [Figure 12] This is a schematic bottom view showing a wound electrode body according to one embodiment of the present disclosure. [Figure 13] This is a schematic perspective view showing a wound electrode body according to one embodiment of the present disclosure, viewed from below. [Figure 14] This is a schematic plan view showing a state in which a wound positive electrode plate is extended into a planar shape in a storage cell according to a modified embodiment of one embodiment of the present disclosure. [Figure 15] This is a schematic cross-sectional view showing the state immediately after the positive electrode plate, negative electrode plate, and separator are wound together when manufacturing a wound electrode body according to a modified embodiment of one embodiment of the present disclosure. [Figure 16] This is a schematic perspective view showing a modified example of a wound electrode body according to one embodiment of the present disclosure. [Modes for carrying out the invention]
[0026] Hereinafter, one embodiment of the present disclosure will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals, and their descriptions will not be repeated.
[0027] Figure 1 is a cross-sectional view showing an overall representation of a battery storage cell according to one embodiment of the present disclosure. The battery storage cell 100 is, for example, a lithium-ion battery mounted in a vehicle. on It is a battery. Note that the applications and types of the energy storage cell 100 are not limited to the examples given above.
[0028] An energy storage cell 100 according to one embodiment of the present disclosure comprises a wound electrode body 1, a case 2, a positive electrode terminal 3, a positive electrode current collector plate 4, an external gasket 5, an internal gasket 6, and a negative electrode current collector plate 7.
[0029] The wound electrode body 1 is housed in case 2. Case 2 has a cylindrical shape. In other words, the energy storage cell 100 is a cylindrical battery.
[0030] The wound electrode body 1 includes a positive electrode plate 10, a negative electrode plate 20, and a separator 30. The separator 30 is provided between the positive electrode plate 10 and the negative electrode plate 20 in the radial direction R of the wound electrode body 1. The separator 30 separates the positive electrode plate 10 and the negative electrode plate 20. On the other hand, the separator 30 is configured to allow ions (for example, lithium ions) to move between the positive electrode plate 10 (positive electrode active material) and the negative electrode plate 20 (negative electrode active material).
[0031] The wound electrode body 1 is composed of a group of electrode plates in which a positive electrode plate 10 and a negative electrode plate 20 are wound around a separator 30. In this embodiment, the positive electrode plate 10 and the negative electrode plate 20 are examples of the "first electrode" and "second electrode" of this disclosure, respectively. The "first electrode" and "second electrode" of this disclosure may also be the negative electrode plate 20 and the positive electrode plate 10, respectively. The detailed configuration of the wound electrode body 1 will be described later.
[0032] Case 2 has an upper surface 2a, a lower surface 2b, and a circumferential surface 2c. The upper surface 2a is the surface located on one side in the axial direction of the cylindrical shape of Case 2. The upper surface 2a is located on one side in the axial direction Z of the wound electrode body 1 when viewed from the wound electrode body 1. The lower surface 2b is the surface located on the other side in the axial direction of the cylindrical shape of Case 2. The lower surface 2b is located on the other side in the axial direction Z of the wound electrode body 1 when viewed from the wound electrode body 1. The circumferential surface 2c has a cylindrical outer shape. The circumferential surface 2c connects the upper surface 2a and the lower surface 2b. Case 2 is made of copper or aluminum, etc. Case 2 also contains an electrolyte (not shown).
[0033] In Case 2, the height dimension (dimension in the axial direction Z) is, for example, 50 mm or more, 60 mm or more, 70 mm or more, or 80 mm or more. The larger the height dimension (dimension in the axial direction Z) of Case 2, the larger the battery capacity of the energy storage cell 100. Alternatively, the height dimension (dimension in the axial direction Z) of Case 2 is, for example, 150 mm or less, 100 mm or less, or 80 mm or less. The smaller the height dimension (dimension in the axial direction Z) of Case 2, the lower the height of the module housing the energy storage cell 100 can be.
[0034] In Case 2, the diameter dimension (dimension in the radial direction R) is, for example, 15 mm or more, 20 mm or more, 25 mm or more, 30 mm or more, 40 mm or more, 45 mm or more, or 46 mm or more. The larger the diameter dimension (maximum dimension in the radial direction R) of Case 2, the larger the battery capacity of the energy storage cell 100. In Case 2, the diameter dimension (dimension in the radial direction R) is, for example, 100 mm or less, 75 mm or less, 50 mm or less, or 46 mm or less. The smaller the diameter dimension (dimension in the radial direction R) of Case 2, the more densely the energy storage cells 100 can be arranged within the module.
[0035] Figure 2 is a partial cross-sectional view showing an enlarged view of the top surface of the case and its surrounding portion in a storage cell according to one embodiment of the present disclosure.
[0036] As shown in Figures 1 and 2, the positive electrode terminal 3 is located on one side Z1 in the axial direction Z when viewed from the wound electrode body 1. The positive electrode terminal 3 includes a disk portion 3a and a rivet portion 3b. The rivet portion 3b is connected to the disk portion 3a. The rivet portion 3b is provided so as to extend from the center of the disk portion 3a to the other side Z2 in the axial direction Z. The positive electrode terminal 3 is made of aluminum. The disk portion 3a is located on the upper surface portion 2a of the case 2. A through hole 2d is provided in the upper surface portion 2a of the case 2. The rivet portion 3b extends from the disk portion 3a located on the outside of the case 2 through the through hole 2d to the inside of the case 2.
[0037] The positive electrode current collector plate 4 is housed in the case 2. The positive electrode current collector plate 4 is located on one side Z1 in the axial direction Z when viewed from the wound electrode body 1. The positive electrode current collector plate 4 is welded to the unpainted positive electrode portion 11b of the positive electrode plate 10, which will be described later. As a result, the positive electrode current collector plate 4 becomes positively charged. The positive electrode current collector plate 4 is welded to the end portion 3c on the other side Z2 in the axial direction Z of the rivet portion 3b. As a result, the positive electrode terminal 3 becomes positively charged.
[0038] The external gasket 5 is positioned between the disc portion 3a of the positive terminal 3 and the upper surface portion 2a of the case 2. This insulates the positive terminal 3 and the case 2 from each other.
[0039] The internal gasket 6 is positioned inside the case 2, between the case 2 and the positive electrode current collector plate 4. This insulates the case 2 and the positive electrode current collector plate 4 from each other. The rivet portion 3b penetrates the internal gasket 6 and is in contact with the positive electrode current collector plate 4.
[0040] Figure 3 is a partial cross-sectional view showing an enlarged view of the lower surface of the case and its surrounding area in a storage cell according to one embodiment of the present disclosure.
[0041] As shown in Figures 1 and 3, the negative electrode current collector plate 7 is housed in the case 2. The negative electrode current collector plate 7 is located on the other side Z2 in the axial direction Z when viewed from the wound electrode body 1. The negative electrode current collector plate 7 is welded to the unpainted negative electrode portion 21b of the negative electrode plate 20, which will be described later. As a result, the negative electrode current collector plate 7 becomes negatively charged. The negative electrode current collector plate 7 is in contact with the case 2. Specifically, the negative electrode current collector plate 7 is in contact with the lower surface portion 2b and the peripheral surface portion 2c. As a result, the case 2 becomes negatively charged. Consequently, the upper surface portion 2a also becomes negatively charged.
[0042] The detailed configuration of the wound electrode body 1 will now be described. First, the configuration of the positive electrode plate 10 will be described. As shown in Figures 1 and 2, the positive electrode plate 10 includes a positive electrode current collector foil 11 and a positive electrode composite material layer 12. As described above, the positive electrode plate 10 of this embodiment is an example of the "first electrode" of this disclosure, so the positive electrode current collector foil 11 and the positive electrode composite material layer 12 of this embodiment correspond to the "current collector foil" and "electrode material" of this disclosure, respectively.
[0043] The positive electrode composite layer 12 is coated onto a portion of the positive electrode current collector foil 11. The positive electrode composite layer 12 is provided on both sides of the wound electrode body 1 in the radial direction R.
[0044] The positive electrode current collector foil 11 is, for example, aluminum Mi It is formed from materials such as nium. The positive electrode composite layer 12 is formed by coating the surface of the positive electrode current collector foil 11 with a positive electrode slurry and drying it. The positive electrode slurry is a slurry prepared by kneading the materials constituting the positive electrode composite layer 12 with a solvent. The materials constituting the positive electrode composite layer 12 include positive electrode active material and binders. The positive electrode composite layer 12 is in close contact with the separator 30. The thickness of the positive electrode composite layer 12 is, for example, 0.1 μm or more and 1000 μm or less.
[0045] The positive electrode current collector foil 11 has a positive electrode coated portion 11a and a positive electrode uncoated portion 11b. The positive electrode coated portion 11a is the portion on which the positive electrode composite material layer 12 is provided.
[0046] The uncoated positive electrode portion 11b is the portion where the positive electrode composite layer 12 is not provided. The uncoated positive electrode portion 11b extends from the coated positive electrode portion 11a to one side Z1 in the axial direction Z of the wound electrode body 1. The uncoated positive electrode portion 11b is exposed to one side Z1 in the axial direction Z of the wound electrode body 1.
[0047] Figure 4 is a schematic plan view showing a state in which a wound positive electrode plate is unrolled in a planar manner in a storage cell according to one embodiment of the present disclosure. In Figure 4, the winding direction X corresponds to the plane direction of the paper.
[0048] As shown in Figure 4, the positive electrode current collector foil 11 has a substantially rectangular shape when stretched in the winding direction X. That is, in this state, the positive electrode current collector foil 11 has an outer shape such that the length of the positive electrode current collector foil 11 in the first direction D1 is longer than the length of the second direction D2 which intersects the first direction D1. More specifically, the second direction D2 is a direction perpendicular to the first direction D1. The first direction D1 is, The positive plate This corresponds to the winding direction X in the wound state. The second direction D2 is substantially the same direction as the axial direction Z.
[0049] The uncoated portion 11b of the positive electrode extends from the coated portion 11a in the second direction D2 (axial direction Z). The uncoated portion 11b of the positive electrode extends in the first direction D1 (winding direction X).
[0050] The uncoated positive electrode portion 11b has a first fold 11bx, a second fold 11by, and a third fold 11bz.
[0051] The first fold 11bx and the second fold 11by are formed such that the distance between them increases as they move away from the positive electrode coated portion 11a in the second direction D2 (axial direction Z). The end of the first fold 11bx on the positive electrode coated portion 11a side and the end of the second fold 11by on the positive electrode coated portion 11a side coincide with each other. The end of the first fold 11bx opposite to the positive electrode coated portion 11a side is located at the edge of the uncoated positive electrode portion 11b. The end of the second fold 11by opposite to the positive electrode coated portion 11a side is located at the edge of the uncoated positive electrode portion 11b.
[0052] The third fold 11bz is formed on the opposite side of the second fold 11by when viewed from the first fold 11bx. The first fold 11bx and the third fold 11bz are formed such that the distance between them increases as they move away from the positive electrode coated portion 11a in the second direction D2 (axial direction Z). The end of the first fold 11bx on the positive electrode coated portion 11a side and the end of the third fold 11bz on the positive electrode coated portion 11a side coincide with each other. The end of the third fold 11bz opposite to the positive electrode coated portion 11a side is located at the edge of the uncoated positive electrode portion 11b. Note that the third fold 11bz does not necessarily have to be provided in the uncoated positive electrode portion 11b.
[0053] The uncoated positive electrode portion 11b has a plurality of first folds 11bx, a plurality of second folds 11by corresponding to each of the plurality of first folds 11bx, and a plurality of third folds 11bz corresponding to each of the plurality of first folds 11bx. A group of adjacent first folds 11bx, a second fold 11by, and a third fold 11bz constitute a group of folds. The groups of folds are spaced apart from each other in the first direction D1 (winding direction X).
[0054] The uncoated positive electrode portion 11b has a base portion 11bA and an extension portion 11bB. The base portion 11bA is the portion connected to the coated positive electrode portion 11a in the second direction D2 (axial direction Z). The base portion 11bA extends over the entire positive electrode current collector foil 11 in the first direction D1 (winding direction X). The extension portion 11bB is the portion that extends from the base portion 11bA to the side opposite to the coated positive electrode portion 11a. The length of the extension portion 11bB in the first direction D1 is shorter than the length of the base portion 11bA in the first direction D1 (winding direction X). This allows the extension portion 11bB to be easily bent relative to the base portion 11bA (details will be described later). Multiple first folds 11bx, multiple second folds 11by, and multiple third folds 11bz are formed in the extension portion 11bB.
[0055] The extension portion 11bB extends from the end X2 of the base portion 11bA in the first direction D1 (winding direction X). However, the position where the extension portion 11bB extends is not limited to the above. Furthermore, multiple extension portions 11bB, each having the above-described fold, may be provided on the uncoated positive electrode portion 11b.
[0056] The length of the extension portion 11bB in the first direction D1 (winding direction X) is the length in the winding direction X at the position where the extension portion 11bB is located. Winding electrode body 1 It is preferable that the length is longer than 0.5 turns. Also, the length of the extension portion 11bB in the first direction D1 (winding direction X) is in the winding direction X at the position where the extension portion 11bB is located. Winding electrode body 1 It is preferable that the length is longer than the length of one turn. In other words, it is preferable that, in the wound state, at least a portion of the extension 11bB overlaps with another portion of the extension 11bB when viewed from the center of winding. The longer the length of the extension 11bB in the first direction D1 (winding direction X), the greater the degree of freedom of the current path of the extension 11bB. Note that the length of the extension 11bB in the first direction D1 (winding direction X) is in the winding direction X at the position where the extension 11bB is positioned. Winding electrode body 1 It is also preferable that the length be shorter than the length of one full turn. The shorter the length of the extension 11bB in the first direction D1 (winding direction X), the easier it is to bend the extension 11bB relative to the base 11bA. In this specification, the starting end side X1 of the winding direction X means the central end side where winding begins in the winding electrode body 1, and the ending end side X2 of the winding direction X means the outer peripheral end side where winding ends in the winding electrode body 1.
[0057] Furthermore, the length of the extension portion 11bB in the first direction D1 (winding direction X) is preferably 73 mm or more. If the length of the extension portion 11bB in the first direction D1 (winding direction X) is 73 mm or more, the reduction in the degree of freedom of the current path in the positive electrode current collector foil 11 can be further suppressed. The length of the extension portion 11bB in the first direction D1 (winding direction X) may be 1 mm or more, 5 mm or more, 10 mm or more, 25 mm or more, 50 mm or more, 100 mm or more, 145 mm or more, 150 mm or more, 200 mm or more, 500 mm or more, or 1000 mm or more. The length of the extension portion 11bB in the first direction D1 (winding direction X) is preferably 220 mm or less. If the extension portion 11bB is 220 mm or less, it becomes easier to bend the extension portion 11bB relative to the base portion 11bA. Consequently, when the extended portion 11bB is folded radially R after winding, the overlapping portion can be reduced, making it easier to form the folded portion and folded portion described later. The length of the extended portion 11bB in the first direction D1 (winding direction X) may be 2000 mm or less, 1500 mm or less, 1000 mm or less, 750 mm or less, 500 mm or less, 250 mm or less, 200 mm or less, 150 mm or less, 145 mm or less, or 140 mm or less.
[0058] The length of the extension portion 11bB in the second direction D2 is preferably 1 mm or more and 23 mm or less. A length of 1 mm or more in the second direction D2 of the extension portion 11bB allows the extension portion 11bB to be bent more easily relative to the base portion 11bA. Furthermore, a length of 23 mm or less in the second direction D2 of the extension portion 11bB allows the dimensions of the uncoated positive electrode portion 11b in the second direction D2 to be reduced. The length of the extension portion 11bB in the second direction D2 may be 0.1 mm or more, 0.5 mm or more, 5 mm or more, or 10 mm or more. The length of the extension portion 11bB in the second direction D2 may be 100 mm or less, 50 mm or less, 20 mm or less, or 10 mm or less.
[0059] As shown in Figure 2, the uncoated positive electrode portion 11b has a plurality of bent portions 11bC and one or more folded portions 11bD. Before describing the configuration of the bent portions 11bC and folded portions 11bD, an example of a method for forming the bent portions 11bC and folded portions 11bD (a method for manufacturing the wound electrode body 1 and the energy storage cell 100 according to this embodiment) will be described. Note that the method for forming the bent portions 11bC and folded portions 11bD is not limited to the method described below.
[0060] Figure 5 is a schematic perspective view showing the state immediately after the positive electrode plate, negative electrode plate, and separator, which are stacked on top of each other, are wound together during the manufacturing of a wound electrode body. Figure 6 is a schematic cross-sectional view showing the state immediately after the positive electrode plate, negative electrode plate, and separator are wound together during the manufacturing of a wound electrode body. As shown in Figures 5 and 6, immediately after the positive electrode plate 10, negative electrode plate 20, and separator 30 are wound together, the positive electrode current collector foil 11 extends axially Z throughout its entire length. That is, in the state immediately after winding, the uncoated portion 11b of the positive electrode and the extended portion 11bB extend axially Z. Also, in the state immediately after winding, the first fold 11bx, the second fold 11by, and the third fold 11bz may or may not be formed beforehand.
[0061] Figure 7 is a schematic plan view showing the state immediately before the multiple blades are pressed against the extended portion of the uncoated positive electrode immediately after winding. Figure 8 is a schematic plan view showing the state after the multiple blades have been pressed radially against the extended portion of the uncoated positive electrode immediately after winding. As shown in Figures 7 and 8, after the positive electrode plate 10, negative electrode plate 20, and separator 30 are wound together, multiple blades 200 are pressed against the extended portion 11bB of the uncoated positive electrode portion 11b.
[0062] Multiple blades 200 are pressed against the winding electrode body immediately after winding, from the radially outer side toward the winding center. The multiple blades 200 are arranged in the circumferential direction of the winding electrode body immediately after winding, spaced apart from each other. Multiple blades 200 are adjacent to each other at multiple folds. groupThey are pressed against each other. Note that the first fold 11bx, the second fold 11by, and the third fold 11bz may be formed for the first time at this point. As the multiple blades 200 are pressed against the extension portion 11bB of the uncoated positive electrode portion 11b as described above, the extension portion 11bB is bent radially inward of the wound electrode body 1. In order to bend the extension portion 11bB uniformly, it is preferable that the multiple blades 200 are arranged at approximately equal intervals along the winding direction X. Furthermore, in order to bend the entire extension portion 11bB radially R, it is preferable that the number of multiple blades 200 pressed against the extension portion 11bB be four or more, and more preferably eight or more.
[0063] Next, the multiple blades 200 bend toward one side in the circumferential direction of the wound electrode body 1. More specifically, the blades 200 located on the opposite side of the second fold 11by from the first fold 11bx bend toward the area between the first fold 11bx and the third fold 11bz. As a result, the region of the extended portion 11bB of the uncoated positive electrode portion 11b between the first fold 11bx and the second fold 11by is folded. In addition, the region of the extended portion 11bB of the uncoated positive electrode portion 11b between the first fold 11bx and the third fold 11bz is arranged to extend along a direction intersecting the axial direction Z.
[0064] Figure 9 is a schematic top view showing a wound electrode body according to one embodiment of the present disclosure. Figure 10 is a schematic perspective view showing a wound electrode body according to one embodiment of the present disclosure from above. As shown in Figures 7 to 11, when the blade 200 is pressed radially as described above, the extension portion 11bB is bent radially to form a plurality of bent portions 11bC. Then, as described above, when the blade 200 collapses, the region of the extension portion 11bB located between the plurality of bent portions 11bC is folded to form a folded portion 11bD.
[0065] Here, as described above, the end of the first fold 11bx on the positive electrode coated portion 11a side and the end of the second fold 11by on the positive electrode coated portion 11a side coincide with each other. Therefore, the area of the folded portion 11bD formed by folding between the first fold 11bx and the second fold 11by can be reduced. Consequently, the average thickness of the folded portion of the uncoated positive electrode portion 11b in the second direction D2 can be reduced. Furthermore, the third fold 11bz is formed on the opposite side of the second fold 11by side when viewed from the first fold 11bx. Therefore, when folding the first fold 11bx and the second fold 11by, the third fold 11bz is folded first, causing the uncoated positive electrode portion 11b to be folded radially to form the folded portion 11bC. After this, the folded portion 11bD can be formed by bending the third fold 11bz back in the opposite direction. Consequently, the bent portion 11bC and the folded portion 11bD can be easily formed.
[0066] It is also conceivable to pre-form a notch in the extended portion 11bB when forming the bent portion 11bC. However, the formation of the notch in the extended portion 11bB is carried out, for example, by laser irradiation. When the extended portion 11bB is irradiated with a laser, the heat from the laser is transferred to the positive electrode composite layer 12. This heat may damage the positive electrode current collector foil 11 or the positive electrode plate 10. In addition, foreign matter such as fumes may be generated during laser irradiation. Therefore, by providing the folded portion 11bD, damage to the positive electrode current collector foil 11 or the positive electrode plate 10 and the generation of foreign matter such as fumes can be suppressed compared to the case where a notch is formed in the extended portion 11bB.
[0067] Furthermore, when the diameter of case 2 is 46 mm and the extension portion 11bB extends from the end of the base portion 11bA on the terminal side X2 in the first direction D1 (winding direction X) (see Figure 4), it is also preferable that the length of the extension portion 11bB in the first direction D1 (winding direction X) is 145 mm or less. This reduces the area of the overlapping portion of both ends of the extension portion 11bB in the winding direction X when the extension portion 11bB is bent (see Figures 9 and 10). Moreover, when the diameter of case 2 is 46 mm and the extension portion 11bB extends from the end of the base portion 11bA on the terminal side X2 in the first direction D1 (winding direction X) (see Figure 4), it is particularly preferable that the length of the extension portion 11bB in the second direction D2 is 23 mm or less. This prevents parts of the extension 11bB that are symmetrically positioned with respect to the winding center from overlapping when the extension 11bB is folded (see Figures 9 and 10).
[0068] The configuration of the bent portion 11bC and the folded portion 11bD will now be described. As shown in Figures 2, 9, and 10, the uncoated positive electrode portion 11b has a plurality of bent portions 11bC and one or more folded portions 11bD.
[0069] Multiple bent portions 11bC are formed when the uncoated positive electrode portion 11b is bent in the radial direction R (see Figure 2) of the wound electrode body 1. Multiple bent portions 11bC are aligned in the winding direction X. Multiple bent portions 11bC that are adjacent to each other in the winding direction X overlap each other in the axial direction Z.
[0070] The radial length of each of the multiple bent portions 11bC is, for example, 1 mm or more and 23 mm or less. Having a radial length of 1 mm or more for the bent portion 11bC results in a relatively large area of the bent portion 11bC when viewed from the axial direction Z, facilitating welding of the bent portion 11bC to the positive electrode current collector plate 4, etc. Simultaneously, having a radial length of 23 mm or less for the bent portion 11bC results in a relatively small size for the folded portion 11bD. Therefore, the average thickness of the portion of the unpainted positive electrode 11b consisting of the bent portion 11bC and the folded portion 11bD can be reduced. Consequently, the dimensions of the unpainted positive electrode 11b in the axial direction Z of the wound electrode body 1 can be further reduced. Note that the radial length of the bent portion 11bC may be 0.1 mm or more, 0.5 mm or more, 5 mm or more, or 10 mm or more. The radial length of the bent portion 11bC may be 100 mm or less, 50 mm or less, 20 mm or less, 15 mm or less, or 10 mm or less.
[0071] The winding length of each of the multiple bent portions 11bC is, for example, 1 mm or more and 40 mm or less. By having a winding length of 1 mm or more for the bent portion 11bC, the reduction in the degree of freedom of the conductive path in the positive electrode current collector foil 11 can be further suppressed. At the same time, by having a winding length of 40 mm or less for the bent portion 11bC, the deflection of the bent portion 11bC is suppressed. Consequently, the dimensions of the uncoated portion 11b of the positive electrode in the axial direction Z can be made smaller. Note that the winding length of the bent portion 11bC may be 0.1 mm or more, 0.5 mm or more, 5 mm or more, 10 mm, or 20 mm or more. The winding length of the bent portion 11bC may be 20 mm or less, 15 mm or less, 10 mm or less, or 5 mm or less.
[0072] Furthermore, if the diameter of case 2 is 46 mm, and the blades 200 (see Figures 7 and 8) that are pressed against the extension portion 11bB when bending the extension portion 11bB are arranged in a line of four at equal intervals, then the winding length of each of the formed bent portions 11bC will be 40 mm or less. Therefore, from the viewpoint of easily bending the entire extension portion 11bB (facilitating the formation of the bent portion 11bC), it is preferable that the winding length of the bent portion 11bC be 40 mm or less.
[0073] The folded portion 11bD is a region located between a plurality of adjacent folded portions 11bC that is formed by folding. The folded portion 11bD is the portion of the uncoated positive electrode portion 11b between the first fold 11bx and the second fold 11by. The folded portion 11bD is folded such that the first fold 11bx is mountain-folded when viewed from one side Z1 in the axial direction Z. The folded portion 11bD is folded such that the second fold 11by is mountain-folded when viewed from the other side Z2 in the axial direction Z.
[0074] Furthermore, the third fold 11bz is located on the bent portion 11bC (see Figure 2). The third fold 11bz is approximately aligned with the second fold 11by in the axial direction Z.
[0075] Next, the configuration of the negative electrode plate 20 will be described. As shown in Figure 3, the negative electrode plate 20 includes a negative electrode current collector foil 21 and a negative electrode composite material layer 22. The negative electrode plate 20 is an example of the "second electrode" of this disclosure, but the negative electrode plate 20 may also be the "first electrode" of this disclosure. If the negative electrode plate 20 is the "first electrode" of this disclosure, the negative electrode current collector foil 21 and the negative electrode composite material layer 22 may correspond to the "current collector foil" and "electrode material" of this disclosure, respectively.
[0076] The negative electrode composite layer 22 is coated onto a portion of the negative electrode current collector foil 21. The negative electrode composite layer 22 is provided on both sides of the wound electrode body 1 in the radial direction R.
[0077] The negative electrode current collector foil 21 is made of, for example, copper. The negative electrode composite layer 22 is formed by coating the surface of the negative electrode current collector foil 21 with a negative electrode slurry and drying it. The negative electrode slurry is a slurry prepared by kneading the materials constituting the negative electrode composite layer 22 with a solvent. The materials constituting the negative electrode composite layer 22 include a negative electrode active material and a binder. The negative electrode composite layer 22 is in close contact with the separator 30. The thickness of the negative electrode composite layer 22 is, for example, 0.1 μm or more and 1000 μm or less.
[0078] The negative electrode current collector foil 21 has a negative electrode coated portion 21a and a negative electrode uncoated portion 21b. The negative electrode coated portion 21a is the portion on which the negative electrode composite material layer 22 is provided.
[0079] The uncoated negative electrode portion 21b is the portion where the negative electrode composite layer 22 is not provided. The uncoated negative electrode portion 21b extends from the coated negative electrode portion 21a to the other side Z2 in the axial direction Z of the wound electrode body 1. The uncoated negative electrode portion 21b is exposed on the other side Z2 in the axial direction Z of the wound electrode body 1.
[0080] Figure 11 is a schematic plan view showing a state in which a wound negative electrode plate is unrolled in a planar manner in a storage cell according to one embodiment of the present disclosure. In Figure 11, the winding direction X corresponds to the plane direction of the paper.
[0081] As shown in Figure 11, the negative electrode current collector foil 21 has a substantially rectangular shape when stretched in the winding direction X. That is, in this state, the negative electrode current collector foil 21 has an outer shape such that the length in the first direction D1 is longer than the length in the second direction D2 which intersects the first direction D1. More specifically, the second direction D2 is a direction perpendicular to the first direction D1. The first direction D1 is, The negative plate This corresponds to the winding direction X in the wound state. The second direction D2 is substantially the same direction as the axial direction Z.
[0082] The uncoated portion 21b of the negative electrode extends from the coated portion 21a in the second direction D2 (axial direction Z). The uncoated portion 21b of the negative electrode extends in the first direction D1 (winding direction X).
[0083] The uncoated negative electrode portion 21b has a first fold 21bx, a second fold 21by, and a third fold 21bz formed therein.
[0084] The first fold 21bx and the second fold 21by are formed such that the distance between them increases as they move away from the negative electrode coated portion 21a in the second direction D2 (axial direction Z). The end of the first fold 21bx on the negative electrode coated portion 21a side and the end of the second fold 21by on the negative electrode coated portion 21a side coincide with each other. The end of the first fold 21bx opposite to the negative electrode coated portion 21a side is located at the edge of the negative electrode uncoated portion 21b. The end of the second fold 21by opposite to the negative electrode coated portion 21a side is located at the edge of the negative electrode uncoated portion 21b.
[0085] The third fold 21bz is formed on the opposite side of the second fold 21by when viewed from the first fold 21bx. The first fold 21bx and the third fold 21bz are formed such that the distance between them increases as they move away from the negative electrode coated portion 21a in the second direction D2 (axial direction Z). The end of the first fold 21bx on the negative electrode coated portion 21a side and the end of the third fold 21bz on the negative electrode coated portion 21a side coincide with each other. The end of the third fold 21bz opposite to the negative electrode coated portion 21a side is located at the edge of the uncoated negative electrode portion 21b. Note that the third fold 21bz does not necessarily have to be provided in the uncoated negative electrode portion 21b.
[0086] The uncoated negative electrode portion 21b has a plurality of first folds 21bx, a plurality of second folds 21by corresponding to each of the plurality of first folds 21bx, and a plurality of third folds 21bz corresponding to each of the plurality of first folds 21bx. A group of adjacent first folds 21bx, a second fold 21by, and a third fold 21bz constitute a group of folds. The groups of folds are spaced apart from each other in the first direction D1 (winding direction X).
[0087] The uncoated negative electrode portion 21b has a base portion 21bA and an extension portion 21bB. The base portion 21bA is the portion connected to the coated negative electrode portion 21a in the second direction D2 (axial direction Z). The base portion 21bA extends over the entire negative electrode current collector foil 21 in the first direction D1 (winding direction X). The extension portion 21bB is the portion that extends from the base portion 21bA to the side opposite to the coated negative electrode portion 21a. The length of the extension portion 21bB in the first direction D1 is shorter than the length of the base portion 21bA in the first direction D1 (winding direction X). This allows the extension portion 21bB to be easily bent relative to the base portion 21bA (details will be described later). Multiple first folds 21bx, multiple second folds 21by, and multiple third folds 21bz are formed in the extension portion 21bB.
[0088] The extension portion 21bB extends from the end X2 of the base portion 21bA in the first direction D1 (winding direction X). However, the position where the extension portion 21bB extends is not limited to the above. Furthermore, multiple extension portions 21bB, each having the above-described fold, may be provided on the uncoated negative electrode portion 21b.
[0089] The length of the extension portion 21bB in the first direction D1 (winding direction X) is the length in the winding direction X at the position where the extension portion 21bB is located. Winding electrode body 1 It is preferable that the length is longer than 0.5 turns. Also, the length of the extension portion 21bB in the first direction D1 (winding direction X) is in the winding direction X at the position where the extension portion 21bB is positioned. Winding electrode body 1 It is preferable that the length is longer than the length of one turn. In other words, it is preferable that, in the wound state, at least a portion of the extension 21bB overlaps with another portion of the extension 21bB when viewed from the center of winding. The longer the length of the extension 21bB in the first direction D1 (winding direction X), the greater the degree of freedom of the current path in the extension 21bB. Note that the length of the extension 21bB in the first direction D1 (winding direction X) is in the winding direction X at the position where the extension 21bB is positioned. Winding electrode body 1 It is also preferable that the length be shorter than the length of one full turn. The shorter the length of the extension 21bB in the first direction D1 (winding direction X), the easier it is to bend the extension 21bB relative to the base 21bA.
[0090] Furthermore, the length of the extension portion 21bB in the first direction D1 (winding direction X) is preferably 73 mm or more. If the length of the extension portion 21bB in the first direction D1 (winding direction X) is 73 mm or more, the reduction in the degree of freedom of the current path in the negative electrode current collector foil 21 can be further suppressed. The length of the extension portion 21bB in the first direction D1 (winding direction X) may be 1 mm or more, 5 mm or more, 10 mm or more, 25 mm or more, 50 mm or more, 100 mm or more, 145 mm or more, 150 mm or more, 200 mm or more, 500 mm or more, or 1000 mm or more. The length of the extension portion 21bB in the first direction D1 (winding direction X) is preferably 220 mm or less. If the extension portion 21bB is 220 mm or less, it becomes easier to bend the extension portion 21bB relative to the base portion 21bA. Consequently, when the extended portion 21bB is folded radially R after winding, the overlapping portion can be reduced, making it easier to form the folded portion and folded portion described later. The length of the extended portion 21bB in the first direction D1 (winding direction X) may be 2000 mm or less, 1500 mm or less, 1000 mm or less, 750 mm or less, 500 mm or less, 250 mm or less, 200 mm or less, 150 mm or less, 145 mm or less, or 140 mm or less.
[0091] The length of the extension portion 21bB in the second direction D2 is preferably 1 mm or more and 23 mm or less. A length of 1 mm or more in the second direction D2 of the extension portion 21bB allows the extension portion 21bB to be bent more easily relative to the base portion 21bA. Furthermore, a length of 23 mm or less in the second direction D2 of the extension portion 21bB allows the dimensions of the uncoated negative electrode portion 21b in the second direction D2 to be reduced. The length of the extension portion 21bB in the second direction D2 may be 0.1 mm or more, 0.5 mm or more, 5 mm or more, or 10 mm or more. The length of the extension portion 21bB in the second direction D2 may be 100 mm or less, 50 mm or less, 20 mm or less, or 10 mm or less.
[0092] As shown in Figure 3, the uncoated negative electrode portion 21b has a plurality of bent portions 21bC and one or more folded portions 21bD. The bent portions 21bC and folded portions 21bD of the uncoated negative electrode portion 21b can be formed in the same manner as the bent portions 11bC and folded portions 11bD of the uncoated positive electrode portion 11b described above. That is, immediately after winding, the extended portion 21bB (see Figure 11) is bent radially to form a plurality of bent portions 21bC. Then, the region of the extended portion 21bB located between the plurality of bent portions 21bC is folded to form the folded portion 21bD.
[0093] It is also conceivable to pre-form a notch in the extended portion 21bB when forming the bent portion 21bC. However, the formation of the notch in the extended portion 21bB is carried out, for example, by laser irradiation. When the extended portion 21bB is irradiated with a laser, the heat from the laser is transferred to the negative electrode composite layer 22. This heat may damage the negative electrode current collector foil 21 or the negative electrode plate 20. In addition, foreign matter such as fumes may be generated during laser irradiation. Therefore, by providing the folded portion 21bD, damage to the negative electrode current collector foil 21 or the negative electrode plate 20 and the generation of foreign matter such as fumes can be suppressed compared to the case where a notch is formed in the extended portion 21bB.
[0094] Figure 12 is a schematic bottom view showing a wound electrode body according to one embodiment of the present disclosure. Figure 13 is a schematic perspective view showing a wound electrode body according to one embodiment of the present disclosure from below.
[0095] When the diameter of case 2 is 46 mm and the extension portion 21bB extends from the end of the base portion 21bA on the terminal side X2 in the first direction D1 (winding direction X) (see Figure 11), it is also preferable that the length of the extension portion 21bB in the first direction D1 (winding direction X) is 145 mm or less. This reduces the area of the overlapping portion of both ends of the extension portion 21bB in the winding direction X when the extension portion 21bB is bent, as shown in Figures 12 and 13. Furthermore, when the diameter of case 2 is 46 mm and the extension portion 21bB extends from the end of the base portion 21bA on the terminal side X2 in the first direction D1 (winding direction X) (see Figure 11), it is particularly preferable that the length of the extension portion 21bB in the second direction D2 is 23 mm or less. This prevents overlapping of parts of the extension 21bB that are symmetrically positioned with respect to the winding center when the extension 21bB is folded (see Figures 12 and 13).
[0096] As shown in Figures 12 and 13, the multiple bent portions 21bC are formed when the uncoated negative electrode portion 21b is bent in the radial direction R (see Figure 3) of the wound electrode body 1. The multiple bent portions 21bC are aligned in the winding direction X. Multiple bent portions 21bC that are adjacent to each other in the winding direction X overlap each other in the axial direction Z.
[0097] The radial length of each of the multiple bent portions 21bC is, for example, 1 mm or more and 23 mm or less. Having a radial length of 1 mm or more for the bent portion 21bC results in a relatively large area of the bent portion 21bC when viewed from the axial direction Z, facilitating welding of the bent portion 21bC to the negative electrode current collector plate 7, etc. Simultaneously, having a radial length of 23 mm or less for the bent portion 21bC results in a relatively small size for the folded portion 21bD. Therefore, the average thickness of the portion of the unpainted negative electrode 21b consisting of the bent portion 21bC and the folded portion 21bD can be reduced. Consequently, the dimensions of the unpainted negative electrode 21b in the axial direction Z of the wound electrode body 1 can be further reduced. Note that the radial length of the bent portion 21bC may be 0.1 mm or more, 0.5 mm or more, 5 mm or more, or 10 mm or more. The radial length of the bent portion 21bC may be 15 mm or less, or 10 mm or less.
[0098] The winding length of each of the multiple bent portions 21bC is, for example, 1 mm or more and 40 mm or less. By having a winding length of 1 mm or more for the bent portion 21bC, the reduction in the degree of freedom of the conductive path in the negative electrode current collector foil 21 can be further suppressed. At the same time, by having a winding length of 40 mm or less for the bent portion 21bC, the deflection of the bent portion 21bC is suppressed. Consequently, the dimensions of the uncoated portion 21b of the negative electrode in the axial direction Z can be made smaller. Note that the winding length of the bent portion 21bC may be 0.1 mm or more, 0.5 mm or more, 5 mm or more, 10 mm or more, or 20 mm or more. The winding length of the bent portion 21bC may be 20 mm or less, 15 mm or less, 10 mm or less, or 5 mm or less. Furthermore, from the viewpoint of easily bending the entire extended portion 21bB (facilitating the formation of the bent portion 21bC), it is preferable that the length of the bent portion 21bC in the winding direction be 40 mm or less.
[0099] The folded portion 21bD is a region located between a plurality of adjacent folded portions 21bC that is formed by folding. The folded portion 21bD is the portion of the uncoated negative electrode portion 21b between the first fold 21bx and the second fold 21by. The folded portion 21bD is folded such that the first fold 21bx is mountain-folded when viewed from the other side Z2 in the axial direction Z. The folded portion 21bD is folded such that the second fold 21by is mountain-folded when viewed from the one side Z1 in the axial direction Z.
[0100] Furthermore, the third fold 21bz is located on the bent portion 21bC (see Figure 3). The third fold 21bz is in the axial direction Z, compared to the second fold. 2 It's roughly on par with 1by.
[0101] As described above, in a storage cell 100 according to one embodiment of the present disclosure, the positive electrode plate 10 includes a positive electrode current collector foil 11 and a positive electrode composite layer 12 coated on a part of the positive electrode current collector foil 11. The positive electrode current collector foil 11 has a positive electrode coated portion 11a and a positive electrode uncoated portion 11b. The positive electrode coated portion 11a is provided with the positive electrode composite layer 12. The positive electrode uncoated portion 11b is not provided with the positive electrode composite layer 12, is exposed on one side Z1 in the axial direction Z of the wound electrode body 1, and extends in the winding direction X of the wound electrode body 1. The positive electrode uncoated portion 11b has a plurality of bent portions 11bC bent toward the radial direction R of the wound electrode body 1, and a folded portion 11bD formed by folding the region located between a plurality of adjacent bent portions 11bC.
[0102] According to the above configuration, since the uncoated portion 11b of the positive electrode is bent in the radial direction R, the dimensions of the uncoated portion 11b of the positive electrode in the axial direction Z of the wound electrode body 1 can be reduced. At the same time, the region between the bent portions 11bC in the uncoated portion 11b of the positive electrode is folded, so that the bent portions 11bC are reliably electrically connected to each other by the folded portion 11bD. Therefore, a decrease in the degree of freedom of the conductive path in the positive electrode current collector foil 11 can be suppressed.
[0103] Furthermore, in a power storage cell 100 according to one embodiment of the present disclosure, the length of the positive electrode current collector foil 11 in a first direction D1 is longer than the length of a second direction D2 intersecting the first direction D1. The positive electrode current collector foil 11 has a positive electrode coated portion 11a and a positive electrode uncoated portion 11b. The positive electrode coated portion 11a is provided with a positive electrode composite material layer 12. The positive electrode uncoated portion 11b is not provided with the positive electrode composite material layer 12 and extends from the positive electrode coated portion 11a in a second direction D2. The positive electrode uncoated portion 11bb has a first fold 11bx and a second fold 11by. The first fold 11bx and the second fold 11by are formed such that the distance between them increases as they move away from the positive electrode coated portion 11a in the second direction D2.
[0104] According to the above configuration, by winding the positive electrode current collector foil 11 and bending the first fold 11bx and the second fold 11by of the uncoated portion 11b of the positive electrode, the uncoated portion 11b can be easily bent in the radial direction R with respect to the winding direction X. By bending the uncoated portion 11b toward the radial direction R, the dimensions of the uncoated portion 11b in the second direction D2 can be reduced. Furthermore, by bending the first fold 11bx and the second fold 11by, the region between the first fold 11bx and the second fold 11by can be folded. This maintains the state in which the uncoated portion 11b is continuous with the first direction D1. Therefore, a decrease in the degree of freedom of the conductive path in the positive electrode current collector foil 11 can be suppressed.
[0105] Furthermore, in a power storage cell 100 according to one embodiment of the present disclosure, the negative electrode plate 20 includes a negative electrode current collector foil 21 and a negative electrode composite layer 22 coated on a part of the negative electrode current collector foil 21. The negative electrode current collector foil 21 has a negative electrode coated portion 21a and a negative electrode uncoated portion 21b. The negative electrode coated portion 21a is provided with the negative electrode composite layer 22. The negative electrode uncoated portion 21b is not provided with the negative electrode composite layer 22, is exposed on the other side Z2 in the axial direction Z of the wound electrode body 1, and extends in the winding direction X of the wound electrode body 1. The negative electrode uncoated portion 21b has a plurality of bent portions 21bC bent toward the radial direction R of the wound electrode body 1, and a folded portion 21bD formed by folding the region located between a plurality of adjacent bent portions 21bC.
[0106] According to the above configuration, since the uncoated portion 21b of the negative electrode is bent in the radial direction R, the dimensions of the uncoated portion 21b of the negative electrode in the axial direction Z of the wound electrode body 1 can be reduced. At the same time, the region between the bent portions 21bC in the uncoated portion 21b of the negative electrode is folded, so that the bent portions 21bC are reliably electrically connected to each other by the folded portion 21bD. Therefore, a decrease in the degree of freedom of the conductive path in the negative electrode current collector foil 21 can be suppressed.
[0107] Furthermore, in the energy storage cell 100 according to one embodiment of the present disclosure, the length of the negative electrode current collector foil 21 in the first direction D1 is longer than the length of the second direction D2 intersecting the first direction D1. The negative electrode current collector foil 21 has a negative electrode coated portion 21a and a negative electrode uncoated portion 21b. The negative electrode coated portion 21a is provided with a negative electrode composite layer 22. The negative electrode uncoated portion 21b is not provided with a negative electrode composite layer 22 and extends from the negative electrode coated portion 21a in the second direction D2. The negative electrode uncoated portion 21bb has a first fold 21bx and a second fold 21by. The first fold 21bx and the second fold 21by are formed such that the distance between them increases as they move away from the negative electrode coated portion 21a in the second direction D2.
[0108] According to the above configuration, by folding the first fold 21bx and the second fold 21by of the uncoated portion 21b of the negative electrode while winding the negative electrode current collector foil 21, the uncoated portion 21b of the negative electrode can be easily folded in the radial direction R with respect to the winding direction X. By folding the uncoated portion 21b of the negative electrode toward the radial direction R, the dimensions of the uncoated portion 21b of the negative electrode in the second direction D2 can be reduced. Furthermore, by folding the first fold 21bx and the second fold 21by, the region between the first fold 21bx and the second fold 21by can be folded. As a result, the state in which the uncoated portion 21b of the negative electrode is continuous with respect to the first direction D1 is maintained. Therefore, a decrease in the degree of freedom of the conductive path in the negative electrode current collector foil 21 can be suppressed.
[0109] In addition, in a storage cell according to one embodiment of the present disclosure, the unpainted portions (positive electrode unpainted portion 11b, negative electrode unpainted portion 21b) may have a plurality of extensions that are separated from each other. The following describes an example of a positive electrode unpainted portion having a plurality of extensions, but the negative electrode unpainted portion may also have a plurality of extensions, similar to the positive electrode unpainted portion in the following modified example.
[0110] Figure 14 is a schematic plan view showing a state in which a wound positive electrode plate is extended into a planar shape in a storage cell according to a modified embodiment of one embodiment of the present disclosure. In Figure 14, the winding direction X corresponds to the plane direction of the paper.
[0111] As shown in Figure 14, in a modified embodiment of the present disclosure, the uncoated positive electrode portion 11b has a plurality of extensions 11bB. The plurality of extensions 11bB include a first extension 11bE and a second extension 11bF.
[0112] In this modified example, the first extension 11bE and the second extension 11bF are aligned in the first direction D1 (winding direction X) and are separated from each other. The first extension 11bE and the second extension 11bF may be separated from each other or adjacent to each other.
[0113] The first extension 11bE extends from the end X2 of the base 11bA in the first direction D1 (winding direction X). The second extension 11bF extends from the base 11bA, from the portion located on the starting end side X1 when viewed from the portion to which the first extension 11bE extends. In this modified example, the length of the first extension 11bE in the second direction D2 is longer than the length of the second extension 11bF in the second direction D2. However, the length of the first extension 11bE in the second direction D2 may be shorter than or the same as the length of the second extension 11bF in the second direction D2.
[0114] Figure 15 is a schematic cross-sectional view showing the state immediately after the positive electrode plate, negative electrode plate, and separator are wound together when manufacturing a wound electrode body according to a modified embodiment of one embodiment of the present disclosure. As shown in Figure 15, in the state immediately after winding when manufacturing the wound electrode body according to this modified embodiment, the second extension portion 11bF is located on the radial side R when viewed from the first extension portion 11bE.
[0115] Figure 16 is a schematic perspective view showing a modified example of a wound electrode body according to one embodiment of the present disclosure. As shown in Figures 15 and 16, the first extension portion 11bE is bent radially to form a plurality of first bent portions 11bG. Then, the region of the first extension portion 11bE located between the plurality of first bent portions 11bG is folded to form a first folded portion 11bH.
[0116] Furthermore, with respect to the first bent portion 11bG and the first folded portion 11bH, the second extended portion 11bF is bent radially on the center side of the radial direction R, forming a plurality of second bent portions 11bI. Then, the region of the second extended portion 11bF located between the plurality of second bent portions 11bI is folded to form a second folded portion 11bJ. The second bent portions 11bI and the second folded portion 11bJ may or may not overlap with the first bent portion 11bG and the first folded portion 11bH.
[0117] The embodiments disclosed herein should be considered in all respects to be illustrative and not restrictive. The scope of this disclosure is indicated by the claims rather than by the description of the embodiments above, and all modifications within the meaning and scope equivalent to the claims are intended to be included. [Explanation of Symbols]
[0118] 1 Electrode body, 2 Case, 2a Top surface, 2b Bottom surface, 2c Peripheral surface, 2d Through hole, 3 Positive electrode terminal, 3a Disc part, 3b Rivet part, 3c End, 4 Positive electrode current collector plate, 5 External gasket, 6 Internal gasket, 7 Negative electrode current collector plate, 10 Positive electrode plate (first electrode), 11 Positive electrode current collector foil (current collector foil), 11a Positive electrode coated part (coated part), 11b Positive electrode uncoated part (uncoated part), 11bA Base part, 11bB Extension part, 11bC Bent part, 11bD Folded part, 11bE First extension part, 11bF Second extension part, 11bG First bent part, 11bH First folded part, 11bI Second bent part, 11bJ Second folding section, 11bx First fold, 11by Second fold, 11bz Third fold, 12 Positive electrode composite layer (electrode material), 20 Negative electrode plate (second electrode), 21 Negative electrode current collector foil, 21a Negative electrode coated section, 21b Negative electrode uncoated section, 21bA Base section, 21bB Extension section, 21bC Bent section, 21bD Folding section, 21bx First fold, 21by Second fold, 21bz Third fold, 22 Negative electrode composite layer, 30 Separator, 100 Energy storage cell, 200 Blade.
Claims
1. A method for manufacturing a wound cylindrical battery including a first electrode, a second electrode, and a separator, A step of placing the separator between the first electrode and the second electrode, A step of winding the first electrode, the second electrode, and the separator, A step of forming a wound electrode body by winding the first electrode, the second electrode, and the separator together, The process involves pressing at least two pressing members against the uncoated portion of the current collector foil of the first electrode or the second electrode, where no electrode material is provided, from the radially outer side of the wound electrode body, toward the winding center, after the winding has been completed. The process includes the step of pressing at least two or more pressing members against the uncoated portion toward the winding center of the wound electrode body, and then pressing down the uncoated portion in the circumferential direction of the wound electrode body. A method for manufacturing cylindrical batteries.
2. Current collector foil and The collection includes an electrode material coated on a portion of the current collector foil, The length of the current collector foil in the first direction is longer than the length in the second direction intersecting the first direction. The aforementioned current collector foil is The coated portion on which the electrode material is provided, The electrode material is not provided, and the coated portion has an uncoated portion extending in the second direction from the coated portion, The uncoated portion has a first fold, a second fold, and a third fold. The third fold is formed on the side opposite to the second fold when viewed from the first fold. The first and second folds are formed such that the distance between them increases as the distance from the coated portion increases in the second direction. A storage cell in which, when the current collector foil is viewed from one side in the thickness direction of the current collector foil, the first fold is a mountain fold, and the second and third folds are valley folds.
3. The energy storage cell according to claim 2, wherein the end of the first fold on the coated side and the end of the second fold on the coated side coincide with each other.
4. The aforementioned unpainted portion is, A base portion connected to the coated portion in the second direction, It includes an extension portion that extends from the base portion on the side opposite to the coated portion portion, The energy storage cell according to claim 2, wherein the length of the extension in the first direction is 73 mm or more, and shorter than the length of the base in the first direction.
5. The energy storage cell according to claim 4, wherein the length of the extension in the first direction is 220 mm or less.
6. The energy storage cell according to claim 4 or claim 5, wherein the length of the extension in the second direction is 1 mm or more and 23 mm or less.