Power storage cell

Abstract

To provide a power storage cell capable of making a thickness of a wound electrode body in a radial direction uniform.SOLUTION: A power storage cell 100 includes: a wound electrode body 1 including a positive electrode plate 10 (first electrode) and a negative electrode body 20 (second electrode); and a case 2 accommodating the wound electrode body 1. The positive electrode plate 10 includes: a positive electrode current collector 11 (current collector); a positive electrode mixture layer 12 (electrode material) with which a portion of the positive electrode current collector 11 is coated; and a positive electrode tab 13 (tab lead). The positive electrode current collector 11 has an uncoated portion 11b that is not coated with the positive electrode mixture layer 12. The positive electrode current collector 11 is folded such that an overlapping portion 14 where the uncoated portions 11b are overlapped on each other in a radial direction of the wound electrode body 1 is formed, and the positive electrode tab lead 13 is disposed in the overlapping portion 14.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present disclosure relates to an energy storage cell. [Background technology]

[0002] Japanese Patent No. 4805545 (Patent Document 1) discloses a lithium secondary battery equipped with a wound-type internal electrode assembly in which a positive electrode plate and a negative electrode plate are arranged with a separator interposed therebetween. Each of the positive electrode plate and the negative electrode plate is provided with a current collecting tab. The current collecting tab is attached to a portion of each of the positive electrode plate and the negative electrode plate where the electrode active material (electrode mixture layer) is not coated and the metal foil body is exposed. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 4805545 Summary of the Invention [Problem to be solved by the invention]

[0004] The internal electrode body in Patent Document 1 includes various components such as a positive electrode plate (negative electrode plate), an electrode composite layer, and a current collecting tab. Therefore, when the internal electrode body is wound, it may be difficult to make the radial thickness of the internal electrode body (wound electrode body) uniform. In this case, steps are likely to occur in the wound electrode body, and when the wound electrode body is constrained by a case or the like, a load is locally applied to the wound electrode body.

[0005] The present disclosure has been made to solve the above-mentioned problems, and an object of the present disclosure is to provide an energy storage cell in which the radial thickness of the wound electrode body can be made uniform. [Means for solving the problem]

[0006] An energy storage cell according to one aspect of the present disclosure includes a wound electrode assembly including a first electrode and a second electrode, and a case that houses the wound electrode assembly. The first electrode includes a current collector, an electrode material coated on a portion of the current collector, and a tab lead that protrudes from the current collector in the axial direction of the wound electrode assembly. The current collector has an uncoated portion that is not coated with the electrode material. The current collector is bent to form an overlapping portion where the uncoated portions overlap in the radial direction of the wound electrode assembly. The tab lead is disposed in the overlapping portion.

[0007] In the energy storage cell according to one aspect of the present disclosure, as described above, the tab lead is disposed in the overlapping portion. This allows the thickness of the first electrode at the location where the tab lead is disposed to be easily adjusted by adjusting the number of overlaps in the overlapping portion. As a result, the thickness of the first electrode can be easily made uniform. This allows the radial thickness of the wound electrode body to be easily made uniform. As a result, the occurrence of steps in the wound electrode body is suppressed, and it is possible to suppress localized loads on the wound electrode body in a constrained state.

[0008] In the energy storage cell according to the above aspect, the current collector preferably has a coated portion where an electrode material is coated. The sum of the radial thickness of the overlapping portion and the radial thickness of the tab lead is defined as a first thickness, and the sum of the radial thickness of the electrode material and the radial thickness of the current collector corresponding to the coated portion is defined as a second thickness. The absolute value of the difference between the first thickness and the second thickness is smaller than the radial thickness of the current collector corresponding to the coated portion. With this configuration, the thickness of the first electrode can be made more uniform than when the absolute value is equal to or greater than the radial thickness of the current collector corresponding to the coated portion.

[0009] In this case, the first thickness is preferably equal to the second thickness, which makes it possible to make the thickness of the first electrode even more uniform.

[0010] In the energy storage cell according to the above aspect, the overlapping portion is preferably provided at an end of the first electrode in the winding direction of the wound electrode body. With this configuration, it is possible to suppress localized load application to the end of the first electrode.

[0011] In the energy storage cell according to the above aspect, the overlapping portion is preferably provided between one end of the first electrode and the other end of the first electrode in the winding direction of the wound electrode body. With this configuration, it is possible to suppress localized load application between the one end of the first electrode and the other end of the first electrode.

[0012] In the energy storage cell according to the above aspect, the overlapping portion is preferably formed by folding the uncoated portion. With this configuration, folding of the coated portion can be suppressed. As a result, peeling of the electrode material due to folding can be suppressed. [Effects of the Invention]

[0013] According to the present disclosure, by arranging the positive electrode tab lead in the overlapping portion, the radial thickness of the wound electrode body can be made uniform. [Brief explanation of the drawings]

[0014] [Figure 1] 1 is a cross-sectional view showing a configuration of a storage cell according to an embodiment. [Figure 2] FIG. 2 is a plan view illustrating the configuration of a positive electrode plate according to one embodiment. [Figure 3] FIG. 2 is a plan view showing the configuration of a negative electrode plate according to one embodiment. [Figure 4] FIG. 10 is a side view illustrating the configuration of an overlapping portion according to one embodiment. [Figure 5] FIG. 10 is a plan view showing a state in which a positive electrode tab lead is attached to an overlapping portion according to an embodiment. [Figure 6] FIG. 4 is a cross-sectional view showing the thickness of a positive electrode plate according to one embodiment. [Figure 7]FIG. 10 is a plan view showing a state in which a positive electrode tab lead is attached to an overlapping portion according to a first modified example of an embodiment. [Figure 8] FIG. 8 is a side view showing the configuration of the overlapping portion of FIG. 7. [Figure 9] FIG. 10 is a plan view showing a state in which a positive electrode tab lead is attached to an overlapping portion according to a second modified example of the embodiment. [Figure 10] FIG. 10 is a plan view showing a state in which a negative electrode tab lead is attached to an overlapping portion according to a third modified example of the embodiment. [Figure 11] FIG. 10 is a cross-sectional view showing the thickness of a positive electrode plate according to a fourth modified example of an embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0015] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are designated by the same reference numerals, and description thereof will not be repeated.

[0016] 1 is a cross-sectional view showing the overall configuration of an energy storage cell 100 according to an embodiment of the present disclosure. The energy storage cell 100 is, for example, a lithium-ion battery mounted on a vehicle. Note that the uses and types of the energy storage cell 100 are not limited to the above examples.

[0017] The energy storage cell 100 includes a wound electrode body 1 , a case 2 , a CID (Current Interrupt Device) 3 , a positive insulating plate 4 , a negative insulating plate 5 , and an insulating layer 6 .

[0018] The wound electrode body 1 is housed in a case 2. The case 2 has a cylindrical shape. That is, the energy storage cell 100 is a cylindrical battery.

[0019] 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. The separator 30 separates the positive electrode plate 10 and the negative electrode plate 20 while allowing ions (e.g., lithium ions) to move between the positive electrode plate 10 (positive electrode active material) and the negative electrode plate 20 (negative electrode active material). The wound electrode body 1 is composed of an electrode plate group in which the positive electrode plate 10 and the negative electrode plate 20 are wound with the separator 30 interposed therebetween. The positive electrode plate 10 and the negative electrode plate 20 are examples of the "first electrode" and the "second electrode," respectively, of the present disclosure.

[0020] FIG. 2 is a view of the positive electrode plate 10 in an unwound state, viewed from the Y1 side. The positive electrode plate 10 has a rectangular shape with long sides extending in the X direction and short sides extending in the Z direction. The X direction is an example of the "winding direction" in the present disclosure. The Z direction is an example of the "axial direction" in the present disclosure. The Y direction is a direction corresponding to the R direction shown in FIG. 1. The R direction is an example of the "radial direction" in the present disclosure.

[0021] 2, positive electrode plate 10 includes positive electrode current collector 11 and positive electrode composite layer 12 (hatched portion). Positive electrode composite layer 12 is coated onto a portion of positive electrode current collector 11. That is, positive electrode current collector 11 includes coated portion 11a coated with positive electrode composite layer 12 and uncoated portion 11b not coated with the positive electrode composite layer.

[0022] In the example shown in FIG. 2, the uncoated portion 11b is provided at each of the X1-side end 10a and the X2-side end 10b of the positive electrode plate 10. The coated portion 11a is provided between the uncoated portion 11b on the X1 side and the uncoated portion 11b on the X2 side. In this embodiment, the X1 side and the X2 side are the winding end side and the winding start side, respectively, of the wound electrode body 1. The positive electrode current collector 11 and the positive electrode composite layer 12 are examples of the "current collector" and "electrode material" of the present disclosure.

[0023] Positive electrode current collector 11 is made of, for example, aluminum. Positive electrode mixture layer 12 is formed by applying a positive electrode slurry to the surface of positive electrode current collector 11 and drying it. The positive electrode slurry is prepared by kneading materials for positive electrode mixture layer 12 (such as a positive electrode active material and a binder) with a solvent. Positive electrode mixture layer 12 is in close contact with separator 30 (see FIG. 1). The thickness of positive electrode mixture layer 12 is, for example, 0.1 μm or more and 1000 μm or less.

[0024] 3 is a view of the unwound negative electrode plate 20 as seen from the Y1 side. Similar to the positive electrode plate 10, the negative electrode plate 20 has a rectangular shape with long sides extending in the X direction and short sides extending in the Z direction.

[0025] 3, negative electrode plate 20 includes negative electrode current collector 21 and negative electrode composite material layer 22 (hatched portion). Negative electrode composite material layer 22 is coated on a portion of negative electrode current collector 21. That is, negative electrode current collector 21 includes coated portion 21a coated with negative electrode composite material layer 22 and uncoated portion 21b not coated with negative electrode composite material layer 22.

[0026] The uncoated portion 21b is provided at each of the X1-side end portion 20a and the X2-side end portion 20b of the negative electrode plate 20. The coated portion 21a is provided between the uncoated portion 21b on the X1 side and the uncoated portion 21b on the X2 side. The coated portion 21a of the negative electrode plate 20 is provided at a position facing the coated portion 11a of the positive electrode plate 10 (a position overlapping in the Y direction). The uncoated portion 21b of the negative electrode plate 20 is provided at a position facing the uncoated portion 11b of the positive electrode plate 10 (a position overlapping in the Y direction). As a result, when the positive electrode plate 10 and the negative electrode plate 20 are wound, the coated portion 11a and the uncoated portion 11b are provided at circumferential positions corresponding to the coated portion 21a and the uncoated portion 21b, respectively.

[0027] For example, copper foil is used for the negative electrode current collector 21. The negative electrode mixture layer 22 is formed by applying a negative electrode slurry to the surface of the negative electrode current collector 21 and drying it. The negative electrode slurry is prepared by kneading the materials for the negative electrode mixture layer 22 (negative electrode active material, binder, etc.) with a solvent. The negative electrode mixture layer 22 is in close contact with the separator 30 (see FIG. 1). The thickness of the negative electrode mixture layer 22 is, for example, 0.1 μm or more and 1000 μm or less.

[0028] 1 again, the positive electrode plate 10 includes a positive electrode tab lead 13. The positive electrode tab lead 13 is provided so as to protrude from the positive electrode current collector 11 (see FIG. 2) toward the Z1 side. The positive electrode tab lead 13 is an example of the "tab lead" of the present disclosure.

[0029] The negative electrode plate 20 includes a negative electrode tab lead 23. The negative electrode tab lead 23 is provided so as to protrude from the negative electrode current collector 21 (see FIG. 2) to the Z2 side.

[0030] The positive-side insulating plate 4 is housed in the case 2. The positive-side insulating plate 4 is provided so as to insulate the wound electrode body 1 (negative electrode plate 20 and separator 30) from the case 2. The positive-side insulating plate 4 is provided so as to cover the positive electrode current collector 11, the negative electrode plate 20, and the separator 30 from the Z1 side.

[0031] The positive insulating plate 4 has a through hole 4a. The positive electrode tab lead 13 passes through the through hole 4a and comes into contact with a conductive film 3b (described later), thereby electrically connecting the positive electrode tab lead 13 and the conductive film 3b.

[0032] The negative insulating plate 5 is housed in the case 2. The negative insulating plate 5 is provided to insulate the wound electrode body 1 (positive electrode plate 10 and separator 30) from the case 2. The negative insulating plate 5 is provided to cover the positive electrode plate 10, negative electrode current collector 21, and separator 30 from the Z2 side.

[0033] The negative insulating plate 5 has a through hole 5a. The negative electrode tab lead 23 passes through the through hole 5a and is in contact with the bottom 2a of the case 2. This electrically connects the negative electrode tab lead 23 to the bottom 2a of the case. As a result, the side surface 2b of the case 2 connected to the bottom 2a of the case 2 is negatively charged. The side surface 2b is in contact with the negative electrode current collector 21 of the negative electrode plate 20 provided on the outermost periphery of the wound electrode body 1.

[0034] CID 3 is an element that interrupts the current path by utilizing an increase in the internal cell pressure caused by gas generated due to overcharging of the energy storage cell 100. CID 3 is provided to seal the opening on the Z1 side of the case 2. CID 3 has an outer cap 3a, a conductive film 3b, a gasket 3c, and a bottom disk 3d.

[0035] The external cap 3a functions as an external terminal by being electrically connected to an external bus bar (not shown). The external cap 3a is provided with a weak portion 3e (thin portion). When the internal pressure of the case 2 increases, the external cap 3a is easily broken starting from the weak portion 3e. This allows gas to be quickly discharged to the outside of the case 2.

[0036] The conductive film 3b is provided so as to seal the opening on the Z1 side of the case 2. The conductive film 3b includes a protruding portion 3f that protrudes toward the wound electrode body 1 side (Z2 side). The protruding portion 3f is in contact with the positive electrode tab lead 13. As a result, the conductive film 3b is positively charged. The conductive film 3b is also electrically connected to the external cap 3a. As a result, the external cap 3a is also positively charged. The protruding portion 3f is provided so as to penetrate each of the gasket 3c and the bottom disk 3d.

[0037] The conductive film 3b has a weak portion 3g (thin portion) similar to the external cap 3a. The conductive film 3b is easily broken from the weak portion 3g when the internal pressure of the case 2 increases. When the conductive film 3b breaks due to the increase in internal pressure, the contact between the conductive film 3b and the positive electrode tab lead 13 is released. As a result, the positive charge of the conductive film 3b is released, and the positive charge of the external cap 3a is also released. As a result, charging and discharging of the energy storage cell 100 is stopped.

[0038] The case 2 is provided with a crimped portion 2c that is crimped to the outer periphery of the outer cap 3a. The insulating layer 6 is provided so as to insulate the crimped portion 2c from the outer cap 3a (and the conductive film 3b).

[0039] 2, the uncoated portion 11b on the X1 side is provided with a first portion 11c, a second portion 11d, and a third portion 11e that are adjacent to each other in the X direction. Specifically, the first portion 11c, the second portion 11d, and the third portion 11e are arranged in this order from the X1 side. The width W11 in the X direction of the first portion 11c, the width W12 in the X direction of the second portion 11d, and the width W13 in the X direction of the third portion 11e are all equal to each other.

[0040] As shown in Fig. 4, the positive electrode current collector 11 is bent (folded) so as to form an overlapping portion 14 where the uncoated portions 11b (first portion 11c, second portion 11d, and third portion 11e) overlap each other. In Fig. 4, the uncoated portions 11b of the overlapping portion 14 overlap each other in the Y direction. The overlapping portion 14 is formed so that the first portion 11c is sandwiched between the second portion 11d and the third portion 11e.

[0041] The overlapping portion 14 is formed by bending the uncoated portion 11b. That is, a bent portion 11f (see the broken line in FIG. 2) is formed within the region of the uncoated portion 11b. The bent portion 11f is provided so as to extend along the Z direction.

[0042] Here, the wound electrode body 1 includes various components such as a positive electrode plate 10 (negative electrode plate 20), electrode composite layers (12, 22), and tab leads (13, 23). For this reason, with conventional configurations, it may be difficult to make the radial thickness of the wound electrode body uniform. In this case, steps are likely to occur in the wound electrode body, and when the wound electrode body is constrained by a case or the like, a load is applied locally to the wound electrode body.

[0043] Therefore, the energy storage cell 100 of this embodiment is configured so that the positive electrode tab lead 13 is disposed in the overlapping portion 14, as shown in Fig. 5. This makes it possible to easily increase the thickness in the overlapping portion 14 (the total thickness of the overlapping portion 14 and the positive electrode tab lead 13). As a result, it is possible to prevent the formation of a step (a step in the radial direction) in the wound electrode body 1 due to a difference in thickness between the uncoated portion 11b and the coated portion 11a. The positive electrode tab lead 13 is welded to the positive electrode current collector 11 in the overlapping portion 14, for example.

[0044] The positive electrode tab lead 13 is contained within the region of the overlapping portion 14 in the X direction. In other words, the width W1 of the positive electrode tab lead 13 in the X direction is smaller than the width W2 of the overlapping portion 14 in the X direction. The positive electrode tab lead 13 is disposed in the center of the overlapping portion 14 in the X direction. Note that the width W1 and the width W2 may be equal to each other.

[0045] In this embodiment, the overlapping portion 14 is provided at the end 10a on the X1 side of the positive electrode plate 10 in the X direction. That is, when the wound electrode body 1 is wound, the overlapping portion 14 is provided at the end of the winding of the wound electrode body 1.

[0046] As shown in FIG. 6, the positive electrode current collector 11 has a thickness t1 in the Y direction. The thickness t1 is the thickness of one metal foil plate of the positive electrode current collector 11. Therefore, the thickness t11 in the Y direction of the overlapping portion 14 is three times the thickness t1 (t11 = 3 × t1). The thickness t1 is an example of the "thickness in the radial direction of the current collector corresponding to the coated portion" in the present disclosure.

[0047] The positive electrode tab lead 13 has a thickness t2 in the Y direction. Therefore, the thickness t12 of the positive electrode plate 10 corresponding to the overlapping portion 14 is the sum of the thickness t11 of the overlapping portion 14 and the thickness t2 of the positive electrode tab lead 13 (t12 = t11 + t2). In the example shown in FIG. 2, the thickness t2 of the positive electrode tab lead 13 is greater than the thickness t1 of the positive electrode current collector 11. The thickness t2 may be equal to or less than the thickness t1. The thickness t12 is an example of the "first thickness" in the present disclosure.

[0048] Positive electrode mixture layer 12 has a thickness t3 in the Y direction. Therefore, thickness t13 of positive electrode plate 10 corresponding to coated portion 11a is the sum of thickness t3 of positive electrode mixture layer 12 and thickness t1 of positive electrode current collector 11 (t13 = t3 + t1). Note that thickness t3 of positive electrode mixture layer 12 is greater than thickness t2 of positive electrode tab lead 13. Furthermore, thickness t13 is an example of the "second thickness" of the present disclosure.

[0049] In this embodiment, the thickness t12 is equal to the thickness t13. In other words, the positive electrode plate 10 is formed so that the thickness is uniform between the portion corresponding to the overlapping portion 14 and the portion corresponding to the coated portion 11a.

[0050] As described above, in this embodiment, the positive electrode tab lead 13 is disposed in the overlapping portion 14 of the positive electrode current collector 11. This makes it possible to easily increase the thickness (t12) of the positive electrode plate 10 at the location where the positive electrode tab lead 13 is disposed, without changing the thickness (t2) of the positive electrode tab lead 13, etc. As a result, the radial thickness of the wound electrode body 1 can be easily made uniform.

[0051] In the above embodiment, an example has been shown in which the overlapping portion 14 is provided at the end 10a on the X1 side of the positive electrode plate 10, but the present disclosure is not limited to this. The position of the overlapping portion 14 is not limited to the above embodiment.

[0052] FIG. 7 shows a positive electrode plate 110 according to a modified example of the above embodiment. The positive electrode plate 110 includes a positive electrode current collector 111. In the example shown in FIG. 7, the uncoated portion 11b is provided not only at the end 110a on the X1 side of the positive electrode plate 110 and the end 110b on the X2 side, but also between the end 110a and the end 110b. The positive electrode plate 110 and the positive electrode current collector 111 are examples of the "first electrode" and "current collector" of the present disclosure, respectively.

[0053] 7, the overlapping portion 114 is formed by the uncoated portion 11b between the end portion 110a and the end portion 110b. The positive electrode tab lead 13 is attached to the overlapping portion 114.

[0054] 8 is a view of the positive electrode plate 110 of FIG. 7 as viewed from the Z2 side. The overlapping portion 114 is formed by overlapping the first portion 111c, the second portion 111d, and the third portion 111e. The first portion 111c, the second portion 111d, and the third portion 111e are arranged in this order from the X1 side. The overlapping portion 114 is provided such that the second portion 111d is sandwiched between the first portion 111c and the third portion 111e in the Y direction. That is, the overlapping portion 114 is formed by bending the uncoated portion 11b in a meandering shape.

[0055] In the above embodiment, an example was shown in which the overlapping portion 14 was provided at the X1-side end 10a of the positive electrode plate 10, but the present disclosure is not limited to this. As shown in Fig. 9, the overlapping portion 14 may be provided at the X2-side end 10b of the positive electrode body 10. Alternatively, the overlapping portion 14 may be provided at both the X1-side end 10a and the X2-side end 10b.

[0056] In the above embodiment, an example in which the overlapping portion 14 is provided on the positive electrode plate 10 has been shown, but the present disclosure is not limited to this. As shown in FIG. 10, the negative electrode plate 20 may be provided with an overlapping portion 24 where the uncoated portions 21b of the negative electrode current collector 21 are overlapped with each other. In this case, the negative electrode tab lead 23 is attached to the overlapping portion 24. Note that the overlapping portion 14 (24) may be provided on each of the positive electrode plate 10 and the negative electrode plate 20. Further, in the example shown in FIG. 10, the overlapping portion 24 is provided at the end portion 20a on the X1 side of the negative electrode plate 20, but the overlapping portion 24 may be provided at the end portion 20b on the X2 side of the negative electrode plate 20 and between the end portion 20a and the end portion 20b.

[0057] In the above embodiment, an example in which the thickness t12 of the positive electrode plate 10 corresponding to the overlapping portion 14 is equal to the thickness t13 of the positive electrode plate 10 corresponding to the coated portion 11a has been shown, but the present disclosure is not limited to this. As shown in FIG. 11, a difference may occur between the thickness t12 and the thickness t13. In the example shown in FIG. 11, the difference t14 between the thickness t12 and the thickness t13 is smaller than the thickness t1 of one metal foil plate of the positive electrode current collector 11 (|t12 - t13| < t1). Note that in FIG. 11, an example in which the thickness t12 is smaller than the thickness t13 is shown, but the thickness t12 may be larger than the thickness t13.

[0058] In the above embodiment, an example in which the bent portion 11f is formed in the uncoated portion 11b has been shown, but the present disclosure is not limited to this. For example, the uncoated portions 11b may be overlapped with each other by bending the positive electrode current collector 11 along the bent portion formed in the coated portion 11a between the uncoated portions 11b.

[0059] The embodiments disclosed this time should be considered as illustrative in all respects and not restrictive. The scope of the present disclosure is shown not by the description of the above embodiments but by the claims, and it is intended that all modifications within the meaning and scope equivalent to the claims are included.

Description of Reference Numerals

[0060] 1 wound electrode body, 2 case, 10, 110 positive electrode plate (first electrode), 10a, 10b end, 11, 111 positive electrode current collector (current collector), 11a coated portion, 11b uncoated portion, 12 positive electrode composite layer (electrode material), 13 positive electrode tab lead (tab lead), 14, 114 overlapping portion, 20 negative electrode plate (second electrode), 100 energy storage cell, R direction (radial direction), t1 thickness (thickness of current collector corresponding to coated portion), t2 thickness (thickness of tab lead), t3 thickness (thickness of electrode material), t11 thickness (thickness of overlapping portion), t12 thickness (first thickness), t13 thickness (second thickness), t14 difference, X direction (winding direction), Z direction (axial direction).

Claims

1. a wound electrode body including a first electrode and a second electrode; a case that houses the wound electrode body, The first electrode is A current collector; an electrode material coated on a portion of the current collector; a tab lead provided so as to protrude from the current collector in the axial direction of the wound electrode body, The current collector is The electrode material has an uncoated portion that is not coated with the electrode material, The uncoated portions are folded to form overlapping portions in which the uncoated portions overlap each other in the radial direction of the wound electrode body, The tab lead is disposed in the overlapping portion.

2. the current collector has a coated portion to which the electrode material is applied, a first thickness is a sum of a thickness of the overlapping portion in the radial direction and a thickness of the tab lead in the radial direction; When the sum of the thickness of the electrode material in the radial direction and the thickness of the current collector corresponding to the coated portion in the radial direction is defined as a second thickness, The energy storage cell according to claim 1 , wherein an absolute value of a difference between the first thickness and the second thickness is smaller than a thickness in the radial direction of the current collector corresponding to the coated portion.

3. The energy storage cell according to claim 2 , wherein the first thickness is equal to the second thickness.

4. The energy storage cell according to any one of claims 1 to 3, wherein the overlapping portion is provided at an end of the first electrode in the winding direction of the wound electrode body.

5. The storage cell according to any one of claims 1 to 3, wherein the overlapping portion is provided between one end of the first electrode and the other end of the first electrode in the winding direction of the wound electrode body.

6. The energy storage cell according to any one of claims 1 to 3, wherein the overlapping portion is formed by folding the uncoated portion.

Images