Electric storage cell

Abstract

To provide a power storage cell capable of maintaining a wound state of a wound electrode body while suppressing generation of local pressure in the wound electrode body.SOLUTION: The electric storage cell 100 includes a wound electrode body 1 that includes a positive electrode plate 10 (first electrode), a negative electrode plate 20 (second electrode), and separators 30. The positive electrode plate 10 includes a positive electrode current collector 11 (first current collector) and a positive electrode mixture layer 12 (first electrode material layer). A positive electrode uncoated portion 11b of the positive electrode current collector 11, which is not coated with the positive electrode mixture layer 12, is bent in the radial direction. A partial side 11b (first part) which is a part of the positive electrode uncoated part side 11e and a partial side 11e (first proximity part) protruding from the positive electrode coated part side 11a at a position closer to the winding axis α than the partial side 11f are welded and joined.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 internal electrode assembly in which a positive electrode metal foil and a negative electrode metal foil are arranged with a separator interposed therebetween. The internal electrode assembly has a tabless structure in which the ends of the metal foils (positive electrode, negative electrode) are arranged to contact the current collecting members (positive electrode, negative electrode). The internal electrode assembly is housed in a case. [Prior art documents] [Patent documents]

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

[0004] Although not explicitly stated in Patent Document 1, fixing tape is sometimes applied to the side surfaces of the internal electrode body to maintain the wound state of the internal electrode body. Here, the space between the side surfaces of the internal electrode body and the inner peripheral surface of the case is made small to restrict movement of the internal electrode body. For this reason, when the internal electrode body expands, for example, the tape interferes with the case, generating local pressure at the location where the tape is applied.

[0005] The present disclosure has been made to solve the above-mentioned problems, and its purpose is to provide a storage cell that is capable of maintaining the wound state of the wound electrode body while suppressing the generation of local pressure in the wound electrode body. [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, a second electrode, and a separator disposed between the first and second electrodes, and a case that houses the wound electrode assembly. The wound electrode assembly has the first electrode, the second electrode, and the separator wound around a winding axis. The first electrode includes a first current collector and a first electrode material layer that is applied to a portion of the first current collector and faces the separator in the radial direction of the wound electrode assembly. The first current collector has a first coated portion that is coated with the first electrode material layer and a first uncoated portion that protrudes from the first coated portion to one axial side of the wound electrode assembly and is not coated with the first electrode material layer. The first uncoated portion is bent radially, and a first portion that is part of the first uncoated portion and a first adjacent portion of the first uncoated portion that protrudes from the first coated portion at a position closer to the winding axis than the first portion are joined by welding.

[0007] In the energy storage cell according to one aspect of the present disclosure, as described above, the first portion, which is a part of the first uncoated portion, and the first adjacent portion of the first uncoated portion, which is closer to the winding axis than the first portion, are joined together by welding. This makes it possible to prevent the wound electrode body from unwinding due to the joining force created by welding between the first portion and the first adjacent portion. As a result, the wound state of the wound electrode body can be maintained without applying tape to the side surfaces of the wound electrode body. This makes it possible to maintain the wound state of the wound electrode body while suppressing the occurrence of local pressure on the wound electrode body due to the application of tape.

[0008] In the energy storage cell according to the above aspect, the welded portion formed by welding the first portion and the first adjacent portion is preferably provided in a part of the wound electrode body when viewed from one axial side. With this configuration, when the electrolyte is poured from one axial side of the wound electrode body, it is possible to prevent the flow of the electrolyte from being obstructed by the welded portion compared to when the welded portion is provided on the entire (full) surface of the wound electrode body.

[0009] In this case, the welded portion is formed at least in the first portion provided on the outer periphery of the wound electrode body. With this configuration, it is possible to prevent the wound state of the wound electrode body from coming undone from the outer periphery side.

[0010] In the energy storage cell in which the welded portion includes a first portion of the outer periphery, the wound electrode body preferably includes a terminal end portion of the winding. The welded portion is formed in at least the first portion provided in the terminal end portion. With this configuration, it is possible to prevent the wound state of the wound electrode body from unraveling from the terminal end portion, and therefore the wound state of the wound electrode body can be easily maintained.

[0011] In the energy storage cell in which the welded portion includes a first portion on the outer peripheral edge, the welded portion is preferably provided so as to extend from the first portion located on the outer peripheral edge to a first adjacent portion located on the inner peripheral edge of the wound electrode body when viewed from one axial side. With this configuration, the length of the welded portion can be easily increased, and the wound state of the wound electrode body can be easily maintained.

[0012] In the energy storage cell according to the above aspect, the second electrode preferably includes a second current collector and a second electrode material layer coated on a portion of the second current collector and facing the separator in the radial direction. The second current collector has a second coated portion coated with the second electrode material layer and a second uncoated portion protruding from the second coated portion toward the other axial side of the wound electrode body and not coated with the second electrode material layer. The second uncoated portion is bent in the radial direction. A second portion, which is part of the second uncoated portion, and a second adjacent portion of the second uncoated portion protruding from the second coated portion at a position closer to the winding axis than the second portion are joined by welding. With this configuration, the wound state of the wound electrode body can be maintained by utilizing the joining force generated by welding between the second portion and the second adjacent portion. This more reliably maintains the wound state of the wound electrode body. [Effects of the Invention]

[0013] According to the present disclosure, it is possible to maintain the wound state of the wound electrode body while suppressing the occurrence of local pressure in the wound electrode body. [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. 1 is a perspective view showing the configuration of a wound electrode body according to one embodiment. [Figure 3] FIG. 2 is a partial enlarged view of the positive electrode side of FIG. [Figure 4] FIG. 2 is a partially enlarged view of the negative electrode side of FIG. [Figure 5] FIG. 2 is a plan view of a wound electrode body according to one embodiment, as viewed from the Z1 side. [Figure 6] 5A to 5C are schematic cross-sectional views illustrating a method for forming a welded portion of a wound electrode assembly according to one embodiment. [Figure 7] FIG. 2 is a side view of a wound electrode body according to one embodiment, as viewed from the radially outer side. [Figure 8] FIG. 2 is a plan view of a wound electrode body according to one embodiment, as viewed from the Z2 side. [Figure 9] FIG. 10 is a plan view of a wound electrode body according to a first modified example of an embodiment, as viewed from the Z1 side. [Figure 10] FIG. 10 is a plan view of a wound electrode body according to a second modified example of the embodiment, as viewed from the Z1 side. [Figure 11] FIG. 11 is a plan view of a wound electrode body according to a third modified example of an embodiment, as viewed from the Z1 side. [Figure 12] FIG. 10 is a plan view of a wound electrode body according to a fourth modified example of an embodiment, as viewed from the Z1 side. [Figure 13] FIG. 11 is a plan view of a wound electrode body according to a fifth modified example of the embodiment, as viewed from the Z1 side. [Figure 14] FIG. 14 is a cross-sectional view taken along line XIV-XIV in FIG. [Figure 15] FIG. 13 is a side view of a wound electrode body according to a sixth modified example of an embodiment, as viewed from the radially outer side. 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 assembly 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 .

[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. The case 2 is made of copper, aluminum, or the like.

[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] As shown in FIG. 2, the wound electrode body 1 is formed by winding a positive electrode plate 10, a negative electrode plate 20, and a separator 30 around a winding axis α.

[0021] 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 toward the Z2 side. The positive electrode terminal 3 is made of aluminum.

[0022] 3, the disk portion 3a is disposed on the upper surface 2a (surface on the Z1 side) of the case 2. A through hole 2b is provided in the upper surface 2a of the case 2. The rivet portion 3b extends from the disk portion 3a, which is disposed outside the case 2, through the through hole 2b to the inside of the case 2.

[0023] The positive current collector 4 is housed in the case 2. The positive current collector 4 is welded to a positive electrode uncoated portion 11b (described later) of the positive plate 10 on the Z1 side of the wound electrode body 1. As a result, the positive current collector 4 is positively charged. The positive current collector 4 is welded to an end 3c on the Z2 side of the rivet portion 3b. As a result, the positive terminal 3 is positively charged.

[0024] The external gasket 5 is disposed between the disk portion 3a of the positive electrode terminal 3 and the upper surface 2a of the case 2. This insulates the positive electrode terminal 3 from the case 2.

[0025] The internal gasket 6 is disposed inside the case 2, between the case 2 and the positive current collector plate 4. This insulates the case 2 from the positive current collector plate 4. The rivet portion 3b penetrates the internal gasket 6 and comes into contact with the positive current collector plate 4.

[0026] As shown in FIG. 4, the negative electrode current collector 7 is housed in the case 2. The negative electrode current collector 7 is welded to a negative electrode uncoated portion 21b (described later) of the negative electrode plate 20 on the Z2 side of the wound electrode body 1. As a result, the negative electrode current collector 7 is negatively charged. The negative electrode current collector 7 is in contact with the case 2. As a result, the case 2 is negatively charged.

[0027] Referring again to FIG. 3, positive electrode plate 10 includes positive electrode current collector 11 and positive electrode composite layer 12. Positive electrode composite layer 12 is applied to both surfaces in the radial direction (R direction) of positive electrode current collector 11 (positive electrode coated portion 11a described below). Positive electrode composite layer 12 faces separator 30 in the R direction. Positive electrode current collector 11 and positive electrode composite layer 12 are examples of a "first current collector" and a "first electrode material layer," respectively.

[0028] 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. The thickness of positive electrode mixture layer 12 is, for example, 0.1 μm or more and 1000 μm or less.

[0029] The positive electrode current collector 11 includes a positive electrode coated portion 11a and a positive electrode uncoated portion 11b. The positive electrode coated portion 11a is a portion of the positive electrode current collector 11 that is coated with a positive electrode composite layer 12. The positive electrode coated portion 11a is sandwiched between separators 30. The positive electrode coated portion 11a and the positive electrode uncoated portion 11b are examples of a "first coated portion" and a "first uncoated portion" of the present disclosure, respectively.

[0030] The positive electrode uncoated portion 11b is a portion of the positive electrode current collector 11 that is not coated with the positive electrode composite layer 12. The positive electrode uncoated portion 11b is located on the Z1 side of the positive electrode coated portion 11a. Specifically, the positive electrode uncoated portion 11b protrudes from the positive electrode coated portion 11a toward the Z1 side. The Z1 side is an example of "one axial side" in the present disclosure.

[0031] The positive electrode uncoated portion 11b includes a portion 11c extending along the Z direction and a portion 11d extending along the R direction. The positive electrode uncoated portion 11b is bent radially inward. The positive electrode uncoated portion 11b is bent into an L shape. The portion 11d of the positive electrode uncoated portion 11b is in contact with the positive electrode current collector plate 4. This causes the positive electrode current collector plate 4 to be positively charged. The positive electrode uncoated portion 11b (portion 11d) is joined to the positive electrode current collector plate 4 by welding.

[0032] A plurality of positive electrode uncoated portions 11b are arranged side by side along the winding direction. A slit 11g (see FIG. 5) is provided between adjacent positive electrode uncoated portions 11b in the winding direction. Among the plurality of positive electrode uncoated portions 11b, adjacent positive electrode uncoated portions 11b in the R direction are arranged so as to partially overlap each other.

[0033] 4 again, the negative electrode plate 20 includes a negative electrode current collector 21 and a negative electrode composite layer 22. The negative electrode composite layer 22 is applied to both surfaces of the negative electrode current collector 21 (a negative electrode coated portion 21a described later) in the radial direction (R direction). The negative electrode composite layer 22 faces the separator 30 in the R direction. The negative electrode current collector 21 and the negative electrode composite layer 22 are examples of the "second current collector" and the "second electrode material layer" of the present disclosure, respectively.

[0034] Negative electrode current collector 21 is made of, for example, copper. Negative electrode mixture layer 22 is formed by applying a negative electrode slurry to the surface of negative electrode current collector 21 and drying the coating. The negative electrode slurry is prepared by kneading materials for negative electrode mixture layer 22 (negative electrode active material, binder, etc.) with a solvent. Negative electrode mixture layer 22 is in close contact with separator 30. The thickness of negative electrode mixture layer 22 is, for example, 0.1 μm or more and 1000 μm or less.

[0035] The negative electrode current collector 21 includes a negative electrode coated portion 21a and a negative electrode uncoated portion 21b. The negative electrode coated portion 21a is a portion of the negative electrode current collector 21 that is coated with a negative electrode composite layer 22. The negative electrode coated portion 21a is sandwiched between separators 30. The negative electrode coated portion 21a and the negative electrode uncoated portion 21b are examples of a "second coated portion" and a "second uncoated portion," respectively, of the present disclosure.

[0036] The negative electrode uncoated portion 21b is a portion of the negative electrode current collector 21 that is not coated with the negative electrode composite material layer 22. The negative electrode uncoated portion 21b is located on the Z2 side of the negative electrode coated portion 21a. Specifically, the negative electrode uncoated portion 21b protrudes from the negative electrode coated portion 21a toward the Z2 side. The Z2 side is an example of the "other axial side" in the present disclosure.

[0037] The negative electrode uncoated portion 21b includes a portion 21c extending along the Z direction and a portion 21d extending along the R direction. The negative electrode uncoated portion 21b is bent radially inward. The negative electrode uncoated portion 21b is bent into an L shape. The portion 21d of the negative electrode uncoated portion 21b is in contact with the negative electrode current collector plate 7. As a result, the negative electrode current collector plate 7 is negatively charged. The negative electrode uncoated portion 21b (portion 21d) is joined to the negative electrode current collector plate 7 by welding.

[0038] A plurality of negative electrode uncoated portions 21b are arranged side by side along the winding direction. A slit 21g (see FIG. 8) is provided between adjacent negative electrode uncoated portions 21b in the winding direction. Among the plurality of negative electrode uncoated portions 21b, adjacent negative electrode uncoated portions 21b in the R direction are arranged so as to partially overlap each other.

[0039] In a conventional energy storage cell configuration, fixing tape is sometimes applied to the side surfaces of the wound electrode body to maintain the wound state of the wound electrode body. In this case, when the wound electrode body expands, local pressure is generated at the location of the tape.

[0040] Therefore, in this embodiment, as shown in FIG. 5, portion 11e, which is one of the plurality of positive electrode uncoated portions 11b, and portion 11f, which is another of the plurality of positive electrode uncoated portions 11b, are joined by welding. FIG. 5 is a plan view of the wound electrode body 1 as viewed from the Z1 side. Portion 11f is a portion that protrudes from the positive electrode coated portion 11a at a position closer to the winding axis α than portion 11e. In other words, portion 11f protrudes at a position closer to the winding axis α than the position at which portion 11e protrudes from the positive electrode coated portion 11a. A welded portion 40 (the shaded portion in FIG. 5) is formed by welding portion 11e and portion 11f. Note that portion 11e and portion 11f are examples of the "first portion" and "first adjacent portion" of the present disclosure, respectively.

[0041] The portion 11e is a positive electrode uncoated portion 11b provided on the outer peripheral edge (the radially outermost edge) 1a of the wound electrode body 1. That is, the portion 11e is a positive electrode uncoated portion 11b that protrudes toward the Z1 side from the positive electrode coated portion 11a (see FIG. 3) that is wound radially outermost of the positive electrode current collector 11. Therefore, the welded portion 40 is formed at least in the portion 11e provided on the outer peripheral edge 1a.

[0042] The portion 11f is a positive electrode uncoated portion 11b that protrudes toward the Z1 side from the positive electrode coated portion 11a that is wound radially inward relative to the positive electrode coated portion 11a that is wound radially outward.

[0043] The portion 11f is provided radially inward of the portion 11e. A plurality of the portions 11f are arranged radially inward of the portion 11e. That is, the portion 11e and the plurality of the portions 11f are arranged side by side in the radial direction.

[0044] The portions 11e and 11f are arranged to partially overlap in the Z direction. Furthermore, the portions 11f adjacent in the radial direction are arranged to partially overlap in the Z direction. The welded portion 40 is formed by welding the positive electrode uncoated portions 11b that overlap in the Z direction (the portions 11e and 11f / the adjacent portions 11f). The welded portion 40 is not formed near the outer peripheral edge 1a and near the inner peripheral edge 1b (the radially innermost edge) of the wound electrode body 1 where the portions of the positive electrode uncoated portions 11b do not overlap. Therefore, unwelded portions 41 where no welding has been performed are provided between the welded portion 40 and each of the outer peripheral edge 1a and the inner peripheral edge 1b.

[0045] The welded portion 40 is formed so as to extend linearly in the radial direction. The welded portion 40 (and the welded portion 50 described below) is formed, for example, by irradiating the wound electrode body 1 with a laser from the laser irradiation portion 110 (see FIG. 6) while scanning the wound electrode body 1 in the radial direction (R direction) on the Z1 side of the wound electrode body 1. The welded portion 40 (50) is formed by lap joint welding using the laser irradiation portion 110.

[0046] When viewed from the Z1 side, the welded portion 40 is provided so as to extend from a portion 11e provided on the outer peripheral edge 1a of the wound electrode body 1 to a portion 11f provided on the inner peripheral edge 1b of the wound electrode body 1. In other words, the welded portion 40 is formed from the vicinity of the outer peripheral edge 1a to the vicinity of the inner peripheral edge 1b.

[0047] In the example shown in FIG. 5, two welds 40 are formed. The two welds 40 are provided on opposite sides of the winding axis α. That is, the two welds 40 are provided on a straight line passing through the winding axis α. This makes it possible to form two welds 40 consecutively without changing the scanning direction of the laser irradiation unit 110 (see FIG. 6). Note that one or three or more welds 40 may be formed.

[0048] As can be seen from the above description, the welded portion 40 is provided in a part of the wound electrode body 1 when viewed from the Z1 side. Specifically, the welded portion 40 is formed in a part of the region occupied by the positive electrode uncoated portion 11b when viewed from the Z1 side.

[0049] FIG. 7 is a side view of the wound electrode body 1 as seen from the radially outer side of portion 11e. As shown in FIG. 7, the wound electrode body 1 includes a winding terminal portion 1c. One of the two welds 40, portion 11e, is provided in terminal portion 1c. Therefore, the weld 40 is formed at least in portion 11e provided in terminal portion 1c. Note that providing the weld 40 in terminal portion 1c not only means that the weld 40 is provided at a position that overlaps with terminal portion 1c in the circumferential direction, but also means that the weld 40 is provided near terminal portion 1c in the circumferential direction.

[0050] The negative electrode side is configured similarly to the positive electrode side. Specifically, as shown in FIG. 8, portion 21e, which is one of the plurality of negative electrode uncoated portions 21b, and portion 21f, which is another of the plurality of negative electrode uncoated portions 21b, are joined by welding. FIG. 8 is a plan view of the wound electrode body 1 as viewed from the Z2 side. Portion 21f is a portion that protrudes from the negative electrode coated portion 21a at a position closer to the winding axis α than portion 21e. In other words, portion 21f protrudes at a position closer to the winding axis α than the position at which portion 21e protrudes from the negative electrode coated portion 21a. A welded portion 50 (the shaded portion in FIG. 8) is formed by welding portion 21e and portion 21f. Portion 21e and portion 21f are examples of the "second portion" and "second adjacent portion" of the present disclosure, respectively.

[0051] The portion 21e is provided on the outer peripheral edge 1a of the wound electrode body 1. That is, the portion 21e is the negative electrode uncoated portion 21b that protrudes toward the Z2 side from the negative electrode coated portion 21a (see FIG. 4) that is wound radially outwardly of the negative electrode current collector 21. Therefore, the welded portion 50 is formed at least in the portion 21e that is provided on the outer peripheral edge 1a.

[0052] The portion 21f is a negative electrode uncoated portion 21b that protrudes toward the Z2 side from the negative electrode coated portion 21a that is wound radially inward relative to the negative electrode coated portion 21a that is wound radially outward.

[0053] Portion 21f is provided radially inward of portion 21e. A plurality of portions 21f are arranged radially inward of portion 21e. That is, portion 21e and the plurality of portions 21f are arranged side by side in the radial direction.

[0054] The portions 21e and 21f are arranged to partially overlap in the Z direction. Furthermore, the portions 21f adjacent in the radial direction are arranged to partially overlap in the Z direction. The welded portion 50 is formed by welding the negative electrode uncoated portions 21b that overlap in the Z direction (the portions 21e and 21f / the adjacent portions 21f). The welded portion 50 is not formed near the outer peripheral edge 1a and the inner peripheral edge 1b of the wound electrode body 1 where the portions of the positive electrode uncoated portions 21b do not overlap. Therefore, unwelded portions 51 where no welding has been performed are provided between the welded portion 50 and each of the outer peripheral edge 1a and the inner peripheral edge 1b.

[0055] As can be seen from the above description, the welded portion 50 is provided in a part of the wound electrode body 1 when viewed from the Z2 side. Specifically, the welded portion 50 is formed in a part of the area occupied by the negative electrode uncoated portion 21b when viewed from the Z2 side. The welded portion 50 may be formed in an area that overlaps with the welded portion 40 in the Z direction (an area that coincides with the welded portion 40 in a plan view).

[0056] 7, portion 21e of one of the two welds 50 is provided at terminal end 1c. Note that providing weld 50 at terminal end 1c does not only mean that weld 50 is provided at a position that overlaps terminal end 1c in the circumferential direction, but also means that weld 50 is provided near terminal end 1c in the circumferential direction. This makes it possible to prevent the wound electrode body 1 from unwinding from terminal end 1c from both the Z1 side and the Z2 side.

[0057] As shown in FIG. 7, the circumferential width W1 of the welded portion 40 is smaller than the circumferential width W11 of the positive electrode uncoated portion 11b. The circumferential width W2 of the welded portion 50 is smaller than the circumferential width W21 of the negative electrode uncoated portion 21b. This allows the area of ​​the welded portion 40 (50) to be relatively small, thereby preventing the welded portion 40 (50) from interfering with the injection of electrolyte. The width W1 of the welded portion 40 may be equal to or larger than the width W11 of the positive electrode uncoated portion 11b. The width W2 of the welded portion 50 may be equal to or larger than the width W21 of the negative electrode uncoated portion 21b.

[0058] As described above, in this embodiment, portion 11e, which is part of positive electrode uncoated portion 11b, and portion 11f, which protrudes from positive electrode coated portion 11a at a position closer to the winding axis α than portion 11e, are joined by welding. By joining portion 11e to portion 11f, it is possible to prevent portion 11e from separating from portion 11f. As a result, the wound state of the wound electrode body 1 can be stably maintained. This makes it possible to omit tape for maintaining the wound state of the wound electrode body 1. As a result, it is possible to maintain the wound state of the wound electrode body 1 while suppressing the generation of local pressure in the wound electrode body 1.

[0059] In the above embodiment, an example was shown in which the welded portion 40 (50) was formed in the portion 11e (21e) provided on the outer peripheral edge 1a of the wound electrode body 1, but the present disclosure is not limited to this. The welded portion 40 (50) does not have to be formed in the uncoated portion (11b, 21b) provided on the outer peripheral edge 1a. For example, in the example shown in FIG. 9, the positive electrode uncoated portion 11b provided radially inward of the positive electrode uncoated portion 11b on the outer peripheral edge 1a is the portion 11e. In other words, the welded portion 140 shown in FIG. 9 is not formed in the positive electrode uncoated portion 11b on the outer peripheral edge 1a. The negative electrode side may also be configured in a similar manner.

[0060] In the above embodiment, an example was shown in which the welded portion 40 (50) is provided so as to extend from the vicinity of the outer peripheral edge 1a to the vicinity of the inner peripheral edge 1b, but the present disclosure is not limited to this. The welded portion 40 (50) does not have to extend to the vicinity of the inner peripheral edge 1b. For example, in the example shown in FIG. 10, the welded portion 240 is provided so as to extend from the vicinity of the outer peripheral edge 1a to the center between the outer peripheral edge 1a and the inner peripheral edge 1b. Note that a similar configuration may also be used on the negative electrode side.

[0061] In the above embodiment, an example was shown in which the welded portion 40 (50) is provided so as to extend in the radial direction, but the present disclosure is not limited to this. The welded portion 40 (50) does not have to extend in the radial direction. For example, in the example shown in FIG. 11, the welded portion 340 is provided so as to extend in a direction intersecting both the radial direction and the circumferential direction. Note that a similar configuration may also be used on the negative electrode side.

[0062] In the above embodiment, an example has been shown in which the welded portion 40 (50) is formed linearly so as to extend in the radial direction, but the present disclosure is not limited to this. The welded portion 40 (50) does not have to be formed linearly. For example, in the example shown in FIG. 12, a plurality of welded portions 440 formed by welding the portion 11e and the portion 11f are formed at a distance from each other. The plurality of welded portions 440 are arranged side by side in the radial direction. Note that the plurality of welded portions 440 do not have to be arranged side by side in the radial direction. A similar configuration may also be used on the negative electrode side.

[0063] Fig. 13 is a diagram showing a modified example of Fig. 12. In the example shown in Fig. 13, portion 11e is provided only on the outer peripheral edge 1a of the wound electrode body 1. Furthermore, portion 11e provided only on the outer peripheral edge 1a is provided at the terminal end portion 1c. Fig. 14 is a cross-sectional view taken along line XIV-XIV in Fig. 13.

[0064] In the above embodiment, an example was shown in which the welded portion 40 was formed on the positive electrode side and the welded portion 50 was formed on the negative electrode side, but the present disclosure is not limited to this. Only one of the welded portion 40 and the welded portion 50 may be formed. Fig. 15 shows an example in which the welded portion 50 is not formed and only the welded portion 40 is formed.

[0065] In the above embodiment, an example is shown in which the uncoated portions are welded together using a laser, but the present disclosure is not limited to this. Welding may be performed using methods other than laser (for example, gas welding, brazing, arc welding, etc.).

[0066] In the above embodiment, the positive electrode uncoated portion 11b and the negative electrode uncoated portion 21b are each bent radially inward, but the present disclosure is not limited to this. At least one of the positive electrode uncoated portion 11b and the negative electrode uncoated portion 21b may be bent radially outward.

[0067] In the above embodiment, an example was shown in which slits 11g were provided between the multiple positive electrode uncoated portions 11b, but the present disclosure is not limited to this. The positive electrode uncoated portions do not necessarily have to have slits. That is, the positive electrode current collector may include a single positive electrode uncoated portion wound around the winding axis α. The same may be true for the negative electrode.

[0068] In the above embodiment, an example was shown in which multiple positive electrode uncoated portions 11b including portions 11c and 11d were provided, but the present disclosure is not limited to this. Multiple portions 11d may be connected to a single portion (corresponding to portion 11c) extending in the winding direction. The same may be true for the negative electrode side.

[0069] The configurations of the above-described embodiment and the above-described modifications may be combined with each other.

[0070] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. The scope of the present disclosure is defined by the claims, not by the description of the above embodiments, and is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0071] 1 wound electrode body, 1a outer peripheral edge, 1b inner peripheral edge, 1c end portion, 2 case, 10 positive electrode plate (first electrode), 11 positive electrode current collector (first current collector), 11a positive electrode coated portion (first coated portion), 11b positive electrode uncoated portion (first uncoated portion), 11e portion (first portion), 11f portion (first adjacent portion), 12 positive electrode composite layer (first electrode material layer), 20 negative electrode plate (second electrode), 21 negative electrode current collector (second current collector), 21a negative electrode coated portion (second coated portion), 21b negative electrode uncoated portion (second uncoated portion), 21e portion (second portion), 21f portion (second adjacent portion), 22 negative electrode composite layer (second electrode material layer), 30 separator, 40 welded portion, 100 storage cell, R Direction (radial direction), Z direction (axial direction), α winding axis.

Claims

1. a wound electrode body including a first electrode, a second electrode, and a separator disposed between the first electrode and the second electrode; a case that houses the wound electrode body, the wound electrode body is formed by winding the first electrode, the second electrode, and the separator around a winding axis, the first electrode includes a first current collector and a first electrode material layer that is applied to a portion of the first current collector and faces the separator in a radial direction of the wound electrode body, The first current collector is a first coated portion on which the first electrode material layer is coated; a first uncoated portion that protrudes from the first coated portion to one side in the axial direction of the wound electrode body and is not coated with the first electrode material layer, The first uncoated portion is bent in the radial direction, a first portion that is a part of the first uncoated portion and a first adjacent portion of the first uncoated portion that protrudes from the first coated portion at a position closer to the winding axis than the first portion are joined by welding.

2. The energy storage cell according to claim 1 , wherein a welded portion formed by welding the first portion and the first adjacent portion is provided in a part of the wound electrode body when viewed from the one axial side.

3. The energy storage cell according to claim 2 , wherein the welded portion is formed at least in the first portion provided on an outer circumferential edge of the wound electrode body.

4. The wound electrode body includes a winding terminal end, The energy storage cell according to claim 3 , wherein the welded portion is formed at least in the first portion provided at the terminal end.

5. 5. The energy storage cell according to claim 3, wherein the welded portion is provided so as to extend from the first portion arranged on the outer peripheral edge to the first adjacent portion arranged on the inner peripheral edge of the wound electrode body when viewed from one side in the axial direction.

6. the second electrode includes a second current collector and a second electrode material layer that is applied to a portion of the second current collector and faces the separator in the radial direction; The second current collector is a second coated portion on which the second electrode material layer is coated; a second uncoated portion that protrudes from the second coated portion to the other axial side of the wound electrode body and is not coated with the second electrode material layer, The second uncoated portion is bent in the radial direction, 5. The energy storage cell according to claim 1, wherein a second portion that is a part of the second uncoated portion and a second adjacent portion of the second uncoated portion that protrudes from the second coated portion at a position closer to the winding axis than the second portion are joined by welding.

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