Energy storage cell

Abstract

Provided is an electricity storage cell that can maintain the wound state of a wound electrode body while suppressing the occurrence of local pressure in the wound electrode body. [Solution] The energy storage cell 100 includes a wound electrode body 1 including a positive electrode plate 10 (first electrode), a negative electrode plate 20 (second electrode), and a separator 30. The positive electrode plate 10 includes a positive electrode current collector 11 (first current collector) and a positive electrode composite layer 12 (first electrode material layer). A positive electrode uncoated portion 11b of the positive electrode current collector 11 that is not coated with the positive electrode composite layer 12 is bent radially. A portion 11e (first portion) that is part of the positive electrode uncoated portion 11b and a portion 11f (first adjacent portion) that protrudes from the positive electrode coated portion 11a at a position closer to the winding axis α than portion 11e are joined by welding.

Description

Technical Field

[0001] The present disclosure relates to a storage battery cell.

Background Art

[0002] Japanese Patent No. 4805545 (Patent Document 1) discloses a lithium secondary battery including a wound internal electrode body in which a positive electrode metal foil body and a negative electrode metal foil body are configured via a separator. The internal electrode body has a tabless structure by being provided such that the ends of the metal foil bodies (positive electrode, negative electrode) contact the current collecting members (positive electrode, negative electrode). Further, the internal electrode body is housed in a case.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Although not specified in the above Patent Document 1, in order to maintain the wound state of the internal electrode body, a fixing tape may be attached to the side surface of the internal electrode body. Here, in order to restrict the movement of the internal electrode body, the space between the side surface of the internal electrode body and the inner peripheral surface of the case is small. Therefore, when the internal electrode body expands or the like, the tape and the case interfere with each other, and local pressure is generated at the portion where the tape is attached.

[0005] The present disclosure has been made to solve the above problems, and an object thereof is to provide a storage battery cell 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 Problems

[0006] A storage cell according to one aspect of the present disclosure comprises a wound electrode body including a first electrode, a second electrode, and a separator disposed between the first electrode and the second electrode, and a case for housing the wound electrode body. The wound electrode body is wound such that the first electrode, the second electrode, and the separator surround the winding axis. The first electrode includes a first current collector and a first electrode material layer coated on a part of the first current collector and facing the separator in the radial direction of the wound electrode body. The first current collector has a first coated portion coated with the first electrode material layer and a first uncoated portion protruding from the first coated portion to one axial side of the wound electrode body and not coated with the first electrode material layer. The first unpainted section is bent radially, and a first portion, which is part of the first unpainted section, and a first adjacent portion of the first unpainted section, which protrudes from the first painted section at a position closer to the winding axis than the first portion, are joined by welding.

[0007] In a storage cell relating to one aspect of this disclosure, as described above, a first portion, which is part of the first unpainted portion, and a first adjacent portion, which is closer to the winding axis than the first portion, are joined to each other by welding. As a result, the welding force between the first portion and the first adjacent portion can prevent the winding of the winding electrode body from unraveling. Consequently, the winding state of the winding electrode body can be maintained without applying tape to the side surface of the winding electrode body. This makes it possible to maintain the winding state of the winding electrode body while suppressing the generation of localized pressure on the winding electrode body caused by the application of tape.

[0008] In the energy storage cell relating to the first aspect described above, preferably, the welded portion formed by welding the first portion and the first adjacent portion is provided on a part of the wound electrode body when viewed from one side in the axial direction. With this configuration, when the electrolyte is injected from one side in the axial direction of the wound electrode body, obstruction of the electrolyte flow by the welded portion can be suppressed compared to when the welded portion is provided on the entire (surface) surface of the wound electrode body.

[0009] In this case, the welded portion is formed on at least the first portion located on the outer edge of the wound electrode body. This configuration makes it possible to suppress the unraveling of the wound state of the wound electrode body from the outer side.

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

[0011] In an energy storage cell in which the welded portion includes a first portion of the outer periphery, preferably, the welded portion is provided to extend from a first portion located on the outer periphery to a first adjacent portion located on the inner periphery of the wound electrode body, when viewed from one side in the axial direction. 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 relating to the first aspect described above, preferably, the second electrode includes a second current collector and a second electrode material layer coated on a part 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 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 radially. A second portion, which is part of the second uncoated portion, and a second adjacent portion of the second uncoated portion, which protrudes 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 winding state of the wound electrode body can be maintained by utilizing the joining force by welding between the second portion and the second adjacent portion. This makes it possible to maintain the winding state of the wound electrode body more reliably. [Effects of the Invention]

[0013] According to the present disclosure, while suppressing the generation of local pressure in the wound electrode body, the wound state of the wound electrode body can be maintained.

Brief Description of the Drawings

[0014] [Figure 1] It is a cross-sectional view showing the configuration of a power storage cell according to an embodiment. [Figure 2] It is a perspective view showing the configuration of a wound electrode body according to an embodiment. [Figure 3] It is a partially enlarged view of the positive electrode side of FIG. 1. [Figure 4] It is a partially enlarged view of the negative electrode side of FIG. 1. [Figure 5] It is a plan view of a wound electrode body according to an embodiment as viewed from the Z1 side. [Figure 6] It is a schematic cross-sectional view showing a method of forming a welded portion of a wound electrode body according to an embodiment. [Figure 7] It is a side view of a wound electrode body according to an embodiment as viewed from the radially outer side. [Figure 8] It is a plan view of a wound electrode body according to an embodiment as viewed from the Z2 side. ​​​​​​​​​​​​​​​​​​​​​​​​

[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 denoted by the same reference numerals, and the description thereof will not be repeated.

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

[0017] The power storage cell 100 includes 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.

[0018] The wound electrode body 1 is housed in the case 2. The case 2 has a cylindrical shape. That is, the power storage cell 100 is a cylindrical battery. Note that the case 2 is formed 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 allows 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), while separating the positive electrode plate 10 and the negative electrode plate 20. The wound electrode body 1 is composed of a plate group in which the positive electrode plate 10 and the negative electrode plate 20 are wound via the separator 30. Note that the positive electrode plate 10 and the negative electrode plate 20 are examples of the "first electrode" and the "second electrode" of the present disclosure, respectively.

[0020] As shown in FIG. 2, the wound electrode body 1 is wound such that the positive electrode plate 10, the negative electrode plate 20, and the separator 30 surround the periphery of the winding axis α.

[0021] Referring again to Figure 1, the positive 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 Z2. The positive terminal 3 is made of aluminum.

[0022] As shown in Figure 3, the disc portion 3a is positioned on the upper surface 2a (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 disc portion 3a, which is located outside the case 2, through the through hole 2b to the inside of the case 2.

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

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

[0025] 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 from the positive electrode current collector plate 4. The rivet portion 3b is in contact with the positive electrode current collector plate 4 by penetrating the internal gasket 6.

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

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

[0028] For example, aluminum is used for the positive electrode current collector 11. The positive electrode composite layer 12 is formed by coating the surface of the positive electrode current collector 11 with a positive electrode slurry and drying it. The positive electrode slurry is a slurry prepared by kneading the materials of the positive electrode composite layer 12 (such as positive electrode active material and binder) with a solvent. 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.

[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 the portion of the positive electrode current collector 11 to which the positive electrode composite material layer 12 is coated. The positive electrode coated portion 11a is sandwiched between the separators 30. The positive electrode coated portion 11a and the positive electrode uncoated portion 11b are examples of the "first coated portion" and "first uncoated portion" as described herein.

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

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

[0032] Multiple uncoated positive electrode portions 11b are arranged in a row along the winding direction. Slits 11g (see Figure 5) are provided between adjacent uncoated positive electrode portions 11b in the winding direction. Among the multiple uncoated positive electrode portions 11b, those adjacent in the R direction are arranged to partially overlap each other.

[0033] Referring again to Figure 4, 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 coated on both radial (R-direction) surfaces of the negative electrode current collector 21 (negative electrode coated portion 21a, described later). 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 "second electrode material layer" of this disclosure, respectively.

[0034] The negative electrode current collector 21 is made of a material such as copper. The negative electrode composite layer 22 is formed by coating the surface of the negative electrode current collector 21 with a negative electrode slurry and drying it. The negative electrode slurry is a slurry prepared by kneading the materials of the negative electrode composite layer 22 (such as negative electrode active material and binder) with a solvent. 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.

[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 the portion of the negative electrode current collector 21 to which the negative electrode composite material layer 22 is coated. The negative electrode coated portion 21a is sandwiched between the separators 30. The negative electrode coated portion 21a and the negative electrode uncoated portion 21b are examples of the "second coated portion" and "second uncoated portion" of this disclosure, respectively.

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

[0037] The unpainted portion 21b of the negative electrode includes a portion 21c extending along the Z direction and a portion 21d extending along the R direction. The unpainted portion 21b of the negative electrode is bent radially inward. The unpainted portion 21b of the negative electrode is bent into an L shape. Portion 21d of the unpainted portion 21b of the negative electrode 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 unpainted portion 21b (portion 21d) of the negative electrode is joined to the negative electrode current collector plate 7 by welding.

[0038] Furthermore, multiple uncoated negative electrode portions 21b are arranged in a row along the winding direction. Slits 21g (see Figure 8) are provided between adjacent uncoated negative electrode portions 21b in the winding direction. In addition, among the multiple uncoated negative electrode portions 21b, those adjacent in the R direction are arranged to partially overlap each other.

[0039] In conventional energy storage cell configurations, fixing tape is sometimes applied to the sides of the wound electrode body to maintain its winding state. In this case, localized pressure is generated at the location of the tape when the wound electrode body expands, etc.

[0040] Therefore, in this embodiment, as shown in Figure 5, a portion 11e, which is one of the multiple uncoated positive electrode portions 11b, and a portion 11f, which is also one of the multiple uncoated positive electrode portions 11b, are joined by welding. Figure 5 is a plan view of the wound electrode body 1 as seen from the Z1 side. Portion 11f is a portion that protrudes from the coated positive electrode portion 11a at a position closer to the winding axis α than portion 11e. That is, portion 11f is a portion that protrudes at a position closer to the winding axis α than the position where portion 11e protrudes from the coated positive electrode portion 11a. A welded portion 40 (shaded portion in Figure 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 this disclosure, respectively.

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

[0042] The portion 11f is the uncoated positive electrode portion 11b that protrudes towards Z1 from the positive electrode coated portion 11a which is wound radially inward, rather than the positive electrode coated portion 11a which is wound radially outward.

[0043] Part 11f is provided radially inward of part 11e. Multiple parts 11f are arranged radially inward of part 11e. That is, part 11e and the multiple parts 11f are arranged side by side along the radial direction.

[0044] Parts 11e and 11f are provided so as to partially overlap in the Z direction. Also, radially adjacent parts 11f are provided so as to partially overlap in the Z direction. The welded portion 40 is formed by welding together overlapping unpainted positive electrode portions 11b (parts 11e and 11f / adjacent portions 11f) in the Z direction. No welded portions 40 are formed near the outer peripheral edge 1a and the inner peripheral edge 1b (the innermost radial edge) of the wound electrode body 1 where the portions of the unpainted positive electrode portions 11b do not overlap. Therefore, an unwelded portion 41 is provided between the welded portion 40 and the outer peripheral edge 1a and the inner peripheral edge 1b, respectively.

[0045] The welded portion 40 is formed to extend linearly along the radial direction. The welded portion 40 (and the welded portion 50 described later) is formed, for example, by irradiating the wound electrode body 1 with a laser from the laser irradiation unit 110 (see Figure 6) while scanning the laser irradiation unit 110 radially (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 unit 110.

[0046] The welded portion 40 is provided so as viewed from the Z1 side, that it extends from the portion 11e provided on the outer peripheral edge 1a of the wound electrode body 1 to the 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 Figure 5, two welds 40 are formed. The two welds 40 are located on opposite sides of the winding axis α. That is, the two welds 40 are located on a straight line passing through the winding axis α. This makes it possible to continuously form the two welds 40 without changing the scanning direction of the laser irradiation unit 110 (see Figure 6). Note that one or more welds 40 may be formed.

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

[0049] Figure 7 is a side view of the wound electrode body 1 viewed from the radially outer side of portion 11e. As shown in Figure 7, the wound electrode body 1 includes the end portion 1c of the winding. Portion 11e of one of the two welds 40 is provided at the end portion 1c. Therefore, the weld 40 is formed at least in the portion 11e provided at the end portion 1c. Note that the statement that the weld 40 is provided at the end portion 1c includes not only the position in which the weld 40 overlaps with the end portion 1c in the circumferential direction, but also the position in the vicinity of the end portion 1c in the circumferential direction.

[0050] The negative electrode side is configured similarly to the positive electrode side. Specifically, as shown in Figure 8, part 21e, which is one of the multiple uncoated negative electrode parts 21b, and part 21f, which is also one of the multiple uncoated negative electrode parts 21b, are joined by welding. Figure 8 is a plan view of the wound electrode body 1 as seen from the Z2 side. Part 21f is a part that protrudes from the coated negative electrode part 21a at a position closer to the winding axis α than part 21e. That is, part 21f is a part that protrudes at a position closer to the winding axis α than the position where part 21e protrudes from the coated negative electrode part 21a. A welded part 50 (shaded part in Figure 8) is formed by welding part 21e and part 21f. Part 21e and part 21f are examples of the "second part" and "second adjacent part" of this 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 uncoated negative electrode portion 21b that protrudes toward Z2 from the negative electrode coated portion 21a (see Figure 4), which is wound most radially outward among the negative electrode current collector 21. Therefore, the welded portion 50 is formed at least on the portion 21e provided on the outer peripheral edge 1a.

[0052] The portion 21f is the uncoated negative electrode portion 21b that protrudes towards Z2 from the negative electrode coated portion 21a which is wound radially inward, rather than the negative electrode coated portion 21a which is wound radially outward.

[0053] Part 21f is provided radially inward of part 21e. Multiple parts 21f are arranged radially inward of part 21e. That is, part 21e and the multiple parts 21f are arranged side by side along the radial direction.

[0054] Parts 21e and 21f are provided so as to partially overlap in the Z direction. Also, radially adjacent parts 21f are provided so as to partially overlap in the Z direction. The welded portion 50 is formed by welding together the unpainted negative electrode portions 21b that overlap in the Z direction (parts 21e and 21f / adjacent portions 21f). No welded portions 50 are formed near the outer peripheral edge 1a and the inner peripheral edge 1b of the wound electrode body 1 where the portions of the unpainted positive electrode portions 21b do not overlap. Therefore, an unwelded portion 51 is provided between the welded portion 50 and the outer peripheral edge 1a and the inner peripheral edge 1b, respectively.

[0055] As can be seen from the above explanation, the welded portion 50 is provided on 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 region occupied by the uncoated negative electrode portion 21b when viewed from the Z2 side. The welded portion 50 may also be formed in a region that overlaps with the welded portion 40 in the Z direction (a region that coincides with the welded portion 40 in a plan view).

[0056] Referring again to Figure 7, a portion 21e of one of the two welds 50 is provided at the end portion 1c. Note that providing the weld 50 at the end portion 1c includes not only the position in which the weld 50 overlaps with the end portion 1c in the circumferential direction, but also the position in the vicinity of the end portion 1c in the circumferential direction. This makes it possible to restrict the unwinding of the winding electrode body 1 from the end portion 1c from both the Z1 side and the Z2 side.

[0057] Furthermore, as shown in Figure 7, the circumferential width W1 of the welded portion 40 is smaller than the circumferential width W11 of the uncoated positive electrode portion 11b. The circumferential width W2 of the welded portion 50 is smaller than the circumferential width W21 of the uncoated negative electrode portion 21b. As a result, the area of ​​the welded portion 40 (50) can be made relatively small, thereby suppressing obstruction of electrolyte injection by the welded portion 40 (50). Note that the width W1 of the welded portion 40 may be greater than or equal to the width W11 of the uncoated positive electrode portion 11b. The width W2 of the welded portion 50 may be greater than or equal to the width W21 of the uncoated negative electrode portion 21b.

[0058] As described above, in this embodiment, a portion 11e, which is part of the uncoated positive electrode portion 11b, and a portion 11f, which protrudes from the coated positive electrode 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 restrict portion 11e from separating from portion 11f. As a result, the winding state of the winded electrode body 1 can be stably maintained. This makes it possible to omit the tape used to maintain the winding state of the winded electrode body 1. As a result, the winding state of the winded electrode body 1 can be maintained while suppressing the generation of localized pressure in the winded electrode body 1.

[0059] In the above embodiment, an example was shown in which the welded portion 40(50) is formed on a portion 11e(21e) provided on the outer peripheral edge 1a of the wound electrode body 1, but the disclosure is not limited thereto. The welded portion 40(50) does not have to be formed on an unpainted portion (11b, 21b) provided on the outer peripheral edge 1a. For example, in the example shown in Figure 9, the portion 11e is the positive electrode unpainted portion 11b provided radially inward from the positive electrode unpainted portion 11b of the outer peripheral edge 1a. That is, the welded portion 140 shown in Figure 9 is not formed on the positive electrode unpainted portion 11b of the outer peripheral edge 1a. The negative electrode side may be configured similarly.

[0060] In the above embodiment, an example was shown in which the welded portion 40(50) extends from the vicinity of the outer peripheral edge 1a to the vicinity of the inner peripheral edge 1b, but the disclosure is not limited thereto. 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 Figure 10, the welded portion 240 is provided 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. The negative electrode side may be configured similarly.

[0061] In the above embodiment, an example was shown in which the weld portion 40(50) extends radially, but the disclosure is not limited thereto. The weld portion 40(50) does not have to extend radially. For example, in the example shown in Figure 11, the weld portion 340 is provided to extend in directions intersecting the radial and circumferential directions, respectively. The negative electrode side may be configured similarly.

[0062] In the above embodiment, an example was shown in which the welded portion 40(50) is formed linearly so as to extend radially, but the disclosure is not limited thereto. The welded portion 40(50) does not have to be formed linearly. For example, in the example shown in Figure 12, multiple welded portions 440 are formed spaced apart from each other by welding portion 11e and portion 11f. The multiple welded portions 440 are arranged in a line along the radial direction. Note that the multiple welded portions 440 do not have to be arranged in a line along the radial direction. The negative electrode side may be configured similarly.

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

[0064] In the above embodiment, an example was shown in which a welded portion 40 is formed on the positive electrode side and a welded portion 50 is formed on the negative electrode side, but the disclosure is not limited thereto. Only one of the welded portion 40 or the welded portion 50 may be formed. Figure 15 shows an example in which no welded portion 50 is formed and only a welded portion 40 is formed.

[0065] The above embodiment shows an example of welding unpainted parts together using a laser, but the disclosure is not limited thereto. Welding may be performed by methods other than lasers (for example, gas welding, brazing, and arc welding).

[0066] In the above embodiment, an example was shown in which the uncoated portion 11b of the positive electrode and the uncoated portion 21b of the negative electrode are each bent radially inward, but the disclosure is not limited thereto. At least one of the uncoated portion 11b of the positive electrode and the uncoated portion 21b of the negative electrode may be bent radially outward.

[0067] In the above embodiment, an example was shown in which slits 11g are provided between multiple uncoated positive electrode portions 11b, but the disclosure is not limited thereto. Slits are not provided in the uncoated positive electrode portions. That is, the positive electrode current collector may include a single uncoated positive electrode portion wound around the winding axis α. The same may apply to the negative electrode side.

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

[0069] Furthermore, the configurations of the above embodiments and each of the above modified examples may be combined with each other.

[0070] 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]

[0071] 1. Winding electrode body, 1a. Outer edge, 1b. Inner 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. Part (first portion), 11f. Part (first proximity 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. Part (second portion), 21f. Part (second proximity portion), 22. Negative electrode composite layer (second electrode material layer), 30. Separator, 40. Welded portion, 100. Energy storage cell, R Direction (radial direction), Z direction (axial direction), α winding axis.

Claims

1. A wound electrode body including an electrode wound in the winding direction so as to surround the winding axis, The case comprises the aforementioned wound electrode body, The electrode comprises a current collector and an electrode material layer coated on a part of the current collector. The aforementioned current collector is The coated portion to which the electrode material layer is coated, The winding electrode body has an uncoated portion located at one end in the axial direction from which the winding axis extends, and the electrode material layer is not coated therein. The uncoated portion has a plurality of tabs that are bent radially in the direction of the wound electrode body and arranged in the direction of the winding, and a welded portion. The welded portion is formed by welding a first tab among the plurality of tabs and a second tab among the plurality of tabs that is located radially inward from the first tab. The aforementioned welded portion comprises a plurality of energy storage cells arranged at intervals in the radial direction.

2. The group of welds, which consists of a plurality of welds arranged radially apart, includes a first group and a second group, The energy storage cell according to claim 1, wherein the first group and the second group are arranged symmetrically with respect to the winding axis.

3. The first group includes, in order from the radially outer side, a first part, a second part, and a third part. The second group includes, in order from the radially outer side, a fourth part, a fifth part, and a sixth part. The first and fourth parts are arranged symmetrically with respect to the winding axis, The second and fifth parts are arranged symmetrically with respect to the winding axis, The energy storage cell according to claim 2, wherein the third and sixth parts are arranged symmetrically with respect to the winding axis.

4. The wound electrode body includes a first end portion in the winding direction and a second end portion in the winding direction located radially outward from the first end portion. The first tab includes the terminal tab located furthest towards the second terminal among the plurality of tabs, The second tab includes a nearby tab located radially inward from the terminal tab, The energy storage cell according to claim 3, wherein the first portion is welded to the terminal tab and the proximity tab.

5. The welded portion includes a first welded portion and a second welded portion located radially inward from the first welded portion, The energy storage cell according to any one of claims 1 to 4, wherein, when the wound electrode body is viewed along the axial direction, the area of ​​the first weld is larger than the area of ​​the second weld.

6. The plurality of welded portions that are spaced apart in the radial direction are The outermost weld, which is located furthest out in the radial direction among the plurality of welds, The innermost weld, which is located furthest inward in the radial direction among the plurality of welds, The energy storage cell according to any one of claims 1 to 4, wherein the radial distance between the outermost weld and the outer peripheral edge of the wound electrode body is smaller than the radial distance between the innermost weld and the winding axis.

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