power storage unit

Abstract

The present disclosure relates to a power storage unit. In the power storage unit, a current collecting plate includes a central portion, an outer peripheral portion, a spoke, a first sheet portion, and a second sheet portion. The central portion is disposed so as to overlap with a center of a wound electrode body when viewed in an axial direction. The outer peripheral portion is located on an outer peripheral side of the central portion. The current collecting plate is electrically connected to a first external terminal by either of the outer peripheral portion and the central portion being connected to a case. The spoke connects the central portion and the outer peripheral portion. The first sheet portion extends from the central portion toward the outer peripheral portion and is connected to a first electrode. The second sheet portion extends from the outer peripheral portion toward the central portion and is connected to the first electrode.

Description

[0001] This invention is a divisional application based on Chinese patent application No. 202411261891.6, filed on September 10, 2024, entitled "Electric Storage Unit". Technical Field

[0002] This disclosure relates to energy storage units. Background Technology

[0003] Japanese Patent No. 3324372 discloses a cylindrical battery in which an electrode assembly consisting of a positive electrode, a negative electrode, and a separator is spirally wound and housed in a battery case. The connection method for the lead portion of the positive electrode is shown as a tabless tab connection. The lead portion of the current collector plate located at the positive electrode is welded to the back of the cover. The overlapping lead portion of the negative electrode is spot-welded to the bottom of the inner casing. Summary of the Invention

[0004] Japanese Patent No. 3324372 discloses that energy storage units such as cylindrical batteries are sometimes charged via fast charging. When an energy storage unit is rapidly charged, it is desirable for the temperature of the unit to rise to some extent. However, in order to maintain the function of the energy storage unit, it is necessary to suppress excessive heat generation within the unit.

[0005] This disclosure was made in view of the aforementioned problems and aims to provide an energy storage unit that can generate moderate heat when energized.

[0006] The energy storage unit based on this disclosure includes a wound electrode body, a housing, and a current collector. The wound electrode body includes a first electrode and a second electrode. The housing houses the wound electrode body and includes a first external terminal. The current collector is disposed within the housing on one side of the wound electrode body along its axial direction. The current collector is provided for housing the first electrode and the first external terminal. The current collector includes a central portion, an outer peripheral portion, spokes, a first plate portion, and a second plate portion. The central portion is disposed such that it overlaps with the center of the wound electrode body when viewed from the axial direction. The outer peripheral portion is located on the outer periphery of the central portion. The current collector is electrically connected to the first external terminal by connecting to the housing via either the outer peripheral portion or the central portion. The spokes connect the central portion and the outer peripheral portion. The first plate portion extends from the central portion toward the outer peripheral portion and is connected to the first electrode. The second plate portion extends from the outer peripheral portion toward the central portion and is connected to the first electrode.

[0007] In the above configuration, firstly, for example, when the outer periphery is connected to the outer casing, the path on the current collector plate, which is connected in the order of the first piece, the central part, the spokes, and the outer periphery, is relatively long. Therefore, when the energy storage unit is energized, the current collector plate generates a relatively large amount of heat along this path. On the other hand, the path on the current collector plate, which is only composed of the second piece and the outer periphery, is relatively short. Therefore, the heat generated when energized along this path is relatively small. Thus, an energy storage unit that generates moderate heat when energized can be provided. Secondly, for example, when the central part is connected to the outer casing, the path on the current collector plate, which is connected in the order of the second piece, the outer periphery, the spokes, and the central part, is relatively long. Therefore, when the energy storage unit is energized, the current collector plate generates a relatively large amount of heat along this path. On the other hand, the path on the current collector plate, which is only composed of the first piece and the central part, is relatively short. Therefore, the heat generated when energized along this path is relatively small. Thus, an energy storage unit that generates moderate heat when energized can be provided.

[0008] In the energy storage unit disclosed herein, it is preferred that the first and second portions are arranged circumferentially with spokes spaced apart from each other around the central portion.

[0009] Based on the above configuration, the longer paths on the current collector plate that generate more heat when energized and the shorter paths on the current collector plate that generate less heat are arranged alternately in the circumferential direction. This reduces the circumferential distribution deviation of the heat generated by the current collector plate when energized.

[0010] In the energy storage unit disclosed herein, it is preferable that the first and second portions are arranged radially with the central portion as the center. This configuration allows the first and second portions to be compactly arranged.

[0011] In the energy storage unit disclosed herein, it is preferred that the first plate and the second plate are welded to the first electrode 11A.

[0012] According to the above configuration, the first plate and the second plate are reliably fixedly connected by the first electrode. Furthermore, the conductive paths through the first plate and through the second plate in the current collector are formed more reliably.

[0013] In the energy storage unit disclosed herein, it is preferred that the housing includes an integral cylindrical wall portion covering the outer periphery of the wound electrode body. The current collector is electrically connected to the first external terminal via the outer periphery portion and the cylindrical wall portion.

[0014] According to the above configuration, the conductive path from the current collector to the first external terminal includes a cylindrical wall portion with a relatively large outer surface area. This allows heat generated in the conductive path during energization to be easily released from the outer surface of the cylindrical wall portion.

[0015] In the energy storage unit disclosed herein, it is preferable that the first external terminal is located at a position overlapping the central portion when viewed from the axial direction. The current collector is electrically connected to the first external terminal via the central portion and the housing.

[0016] According to the above configuration, the conductive path from the current collector to the first external terminal can be shortened, and the heat generation on the conductive path can be suppressed.

[0017] The above and other objects, features, aspects and advantages of the present invention will become apparent from the following detailed description relating to the invention in conjunction with the accompanying drawings. Attached Figure Description

[0018] Figure 1 This is a perspective view showing the energy storage unit according to Embodiment 1.

[0019] Figure 2 It is Figure 1 A cross-sectional view of the energy storage unit as viewed in the direction of the arrow along line II-II.

[0020] Figure 3 It is Figure 1 A cross-sectional view of the energy storage unit as viewed in the direction of the arrow along line III-III.

[0021] Figure 4 It is a three-dimensional view showing a partial breakdown of the wound electrode body.

[0022] Figure 5 This is an exploded perspective view showing the energy storage unit according to Embodiment 1.

[0023] Figure 6 This is an exploded perspective view showing another energy storage unit according to Embodiment 1.

[0024] Figure 7 This is a top view showing the negative current collector in Embodiment 1.

[0025] Figure 8 This is a cross-sectional view showing the energy storage unit according to Embodiment 2.

[0026] Figure 9 This is a top view showing the negative current collector in Embodiment 2.

[0027] Figure 10 This is a cross-sectional view of the energy storage unit involved in Embodiment 3.

[0028] Figure 11 This is another cross-sectional view of the energy storage unit involved in Embodiment 3.

[0029] Figure 12This is an exploded perspective view showing the energy storage unit involved in Embodiment 3.

[0030] Figure 13 This is an exploded perspective view showing another energy storage unit according to Embodiment 3.

[0031] Figure 14 This is a top view showing the positive current collector in Embodiment 3.

[0032] Figure 15 This is a cross-sectional view showing the energy storage unit according to Embodiment 4.

[0033] Figure 16 This is a top view showing the positive current collector in embodiment 4.

[0034] Figure 17 This is a cross-sectional view of the energy storage unit according to Embodiment 5.

[0035] Figure 18 This is an exploded perspective view showing the energy storage unit according to Embodiment 5. Detailed Implementation

[0036] Hereinafter, the energy storage units involved in the various embodiments of this disclosure will be discussed with reference to the accompanying drawings. Figure 1 The same or similar parts in the figure are labeled with the same reference numerals, and their descriptions are not repeated.

[0037] (Implementation Method 1)

[0038] Figure 1 This is a perspective view showing the energy storage unit according to Embodiment 1. Figure 2 It is Figure 1 A cross-sectional view of the energy storage unit as viewed in the direction of the arrow along line II-II. Figure 3 It is Figure 1 A cross-sectional view of the energy storage unit as viewed in the direction of the arrow along line III-III.

[0039] like Figures 1-3 As shown, the energy storage unit 1 is a cylindrical battery. The energy storage unit 1 includes a wound electrode body 10, a housing 20, a positive current collector 30P, and a negative current collector 30N. In Embodiment 1, the negative current collector 30N is exemplified as the current collector (30) in this disclosure.

[0040] First, let’s explain the wound electrode body 10. Figure 4 This is a three-dimensional view showing a partial breakdown of the wound electrode body. For example... Figures 2-4 As shown, the electrode body 10 is wound in a cylindrical shape. Figure 4 The diagram shows the slightly loosened state of the wound electrode body 10.

[0041] The wound electrode body 10 includes a positive electrode 11P, a negative electrode 11N, and a spacer 12. The wound electrode body 10 is wound such that the positive electrode 11P, the negative electrode 11N, and the spacer 12 surround the winding axis α. In Embodiment 1, the negative electrode 11N is exemplified as the first electrode (11A) of this disclosure, and the positive electrode 11P is exemplified as the second electrode (11B).

[0042] The positive electrode 11P and the negative electrode 11N have a sheet-like shape. The wound electrode body 10 is composed of an electrode plate assembly formed by winding the positive electrode 11P and the negative electrode 11N with a separator 12 between them.

[0043] The separator 12 is disposed between the positive electrode 11P and the negative electrode 11N. The separator 12 can both allow ions (e.g., lithium ions) to move between the positive electrode 11P (positive electrode active material) and the negative electrode 11N (negative electrode active material) and separate the positive electrode 11P and the negative electrode 11N.

[0044] The positive electrode 11P comprises a positive current collector 111P and a positive composite material (positive electrode agent) layer 112P. The positive current collector 111P is formed of, for example, aluminum.

[0045] A positive electrode composite material layer 112P is coated on both radial sides of the positive electrode current collector 111P (the positive electrode coating portion 111PA described later). The positive electrode composite material layer 112P is in close contact with the separator 12. The positive electrode composite material layer 112P is formed by coating a positive electrode slurry onto the surface of the positive electrode current collector 111P and then drying it. The positive electrode slurry is a slurry prepared by mixing the material of the positive electrode composite material layer 112P (positive electrode active material, binder, etc.) with a solvent. The thickness of the positive electrode composite material layer 112P is, for example, 0.1 μm or more and 1000 μm or less.

[0046] The positive current collector 111P includes a positive electrode coated portion 111PA and a positive electrode uncoated portion 111PB. The positive electrode coated portion 111PA is the part of the positive current collector 111P coated with a positive electrode composite material layer 112P. In other words, the positive electrode coated portion 111PA is the part that is covered by the positive electrode composite material layer 112P and is not exposed.

[0047] The uncoated portion 111PB is the part of the positive electrode current collector 111P that is not covered by the positive electrode composite material layer 112P. The uncoated portion 111PB is located on the first direction Z1 side along the axial direction Z, closer to the coated portion 111PA. Specifically, the uncoated portion 111PB protrudes from the coated portion 111PA towards the first direction Z1 side. The uncoated portion 111PB is bent radially inward.

[0048] The uncoated portion 111PB of the positive electrode includes a plurality of extended portions 111PC. The plurality of extended portions 111PC are arranged along the winding direction of the wound electrode body 10.

[0049] The negative electrode 11N comprises a negative electrode current collector 111N and a negative electrode composite material (negative electrode agent) layer 112N. The negative electrode current collector 111N is formed of, for example, copper.

[0050] A negative electrode composite material layer 112N is coated on both radial sides of the negative electrode current collector 111N (hereinafter referred to as the negative electrode coating portion 111NA). The negative electrode composite material layer 112N is in close contact with the separator 12. The negative electrode composite material layer 112N is formed by coating a negative electrode slurry onto the surface of the negative electrode current collector 111N and then drying it. The negative electrode slurry is a slurry prepared by mixing the material of the negative electrode composite material layer 112N (negative electrode active material, binder, etc.) with a solvent. The thickness of the negative electrode composite material layer 112N is, for example, 0.1 μm or more and 1000 μm or less.

[0051] The negative electrode current collector 111N includes a negative electrode coated portion 111NA and a negative electrode uncoated portion 111NB. The negative electrode coated portion 111NA is the portion of the negative electrode current collector 111N coated with a negative electrode composite material layer 112N. In other words, the negative electrode coated portion 111NA is the portion that is covered by the negative electrode composite material layer 112N and is not exposed.

[0052] The uncoated negative electrode portion 111NB is the part of the negative electrode current collector 111N that is not covered by the negative electrode composite material layer 112N. The uncoated negative electrode portion 111NB is located on the side along the second axial direction Z2, closer to the coated negative electrode portion 111NA. The second direction Z2 is the opposite direction to the first direction Z1. The uncoated negative electrode portion 111NB protrudes from the coated negative electrode portion 111NA towards the second axial direction Z2. The uncoated negative electrode portion 111NB is bent radially inward.

[0053] The uncoated negative electrode portion 111NB includes multiple extension portions 111NC. The multiple extension portions 111NC are arranged along the winding direction of the wound electrode body 10.

[0054] Next, the outer casing 20 will be explained. Figure 5 This is an exploded perspective view showing the energy storage unit according to Embodiment 1. Figure 6 This is an exploded perspective view showing another energy storage unit according to Embodiment 1.

[0055] like Figures 1-3 , Figure 5 and Figure 6As shown, the housing 20 houses the wound electrode body 10. The housing 20 includes a positive terminal 21P, a negative terminal 21N, a cylindrical wall portion 22, a sealing plate 23, a sealing plug 24, an outer gasket 25, an inner gasket 26, and an annular gasket 27. In Embodiment 1, the negative terminal 21N is exemplified as the first external terminal (21A) in this disclosure, and the positive terminal 21P is exemplified as the second external terminal (21B) in this disclosure.

[0056] The positive terminal 21P is disposed on the first direction Z1 side of the wound electrode body 10. The positive terminal 21P includes a disk portion 211 and a rivet portion 212. The disk portion 211 is exposed to the outside. The rivet portion 212 is connected to the disk portion 211. The rivet portion 212 extends from the center of the disk portion 211 when viewed from the axial direction Z. The rivet portion 212 is located approximately on the winding axis α of the wound electrode body 10. The rivet portion 212 extends towards the second direction Z2 side. The positive terminal 21P is formed of, for example, aluminum.

[0057] The negative terminal 21N is arranged orthogonally to the Z-axis. A through hole 21Nh is provided in the negative terminal 21N. Therefore, the negative terminal 21N has an annular shape when viewed from the Z-axis. The negative terminal 21N is located between the disk portion 211 and the wound electrode body 10 in the Z-axis direction. A rivet portion 212 is inserted through the through hole 21Nh. The rivet portion 212 extends into the interior of the housing 20. The material constituting the negative terminal 21N is not particularly limited, but is formed of aluminum, copper, or stainless steel, etc.

[0058] A cylindrical wall portion 22 is provided on the outer periphery of the wound electrode body 10. The cylindrical wall portion 22 covers the entire outer periphery of the wound electrode body 10. The cylindrical wall portion 22 has a cylindrical shape. The end of the cylindrical wall portion 22 on the first direction Z1 side is connected to the negative terminal 21N. The cylindrical wall portion 22 and the negative terminal 21N are integrally formed. The material constituting the cylindrical wall portion 22 is not particularly limited, but is formed of aluminum, copper, or stainless steel, etc.

[0059] A tightening (gluing) portion 22d is formed at the end of the cylindrical wall portion 22 on the second direction Z2 side. The tightening portion 22d is formed in a circular shape along the circumference of the winding electrode body 10. Furthermore, in Figure 5 and Figure 6 The image shows the cylindrical wall portion 22 before the formation of the constriction portion 22d.

[0060] The sealing plate 23 is connected to the end of the cylindrical wall portion 22 on the second direction Z2 side. The sealing plate 23 seals the opening of the cylindrical wall portion 22 on the second direction Z2 side. The tightening portion 22d tightens around the outer periphery of the sealing plate 23. Alternatively, the sealing plate 23 can also be connected to the cylindrical wall portion 22 by welding, such as laser welding. The material constituting the sealing plate 23 is not particularly limited, but may be formed of aluminum, copper, or stainless steel.

[0061] A through hole 23h is formed in the sealing plate 23. The through hole 23h can be used to inject electrolyte (not shown) contained in the housing 20. The through hole 23h is formed in the center of the sealing plate 23 when viewed from the axial direction Z.

[0062] The sealing bolt 24 is inserted through the through hole 23h of the sealing plate 23. Thus, the sealing bolt 24 is fixed to the sealing plate 23. The sealing bolt 24 and the through hole 23h can function as a pressure relief valve to release the pressure inside the housing 20 when the pressure inside the housing 20 becomes excessively high.

[0063] An external gasket 25 is disposed between the positive terminal 21P and the negative terminal 21N. The external gasket 25 is formed of an insulating material. Therefore, the external gasket 25 insulates the positive terminal 21P and the negative terminal 21N. The external gasket 25 covers the surface of the disk portion 211 in the second direction Z2. The rivet portion 212 passes through the external gasket 25 in the axial Z direction. The external gasket 25 covers the radially inner surface of the through hole 21Nh of the negative terminal 21N.

[0064] The inner gasket 26 covers the surface of the negative terminal 21N in the second direction Z2. The inner gasket 26 is formed of insulating material. Thus, the inner gasket 26 insulates the wound electrode body 10 and the negative terminal 21N. The rivet portion 212 further penetrates the inner gasket 26 in the axial Z direction. Thus, the rivet portion 212 is exposed inside the housing 20.

[0065] The annular gasket 27 has a circular shape. The annular gasket 27 covers the outer periphery of the sealing plate 23. The annular gasket 27 is disposed between the outer periphery of the sealing plate 23 and the constricting portion 22d of the cylindrical wall portion 22. The annular gasket 27 can be formed of an insulating material or a conductive material. Alternatively, the housing 20 may not include the annular gasket 27.

[0066] In this embodiment, the sealing plate 23 is insulated from the cylindrical wall portion 22 by the annular gasket 27, but the sealing plate 23 may also be electrically connected to the cylindrical wall portion 22. In this case, the sealing plate 23 may also be the negative terminal.

[0067] In this embodiment, the portion of the housing 20 facing the first direction Z1 is composed of a positive terminal 21P, a negative terminal 21N, and an outer gasket 25. However, as part of the aforementioned portion, the housing 20 may also have a top plate portion. The top plate portion may, for example, be located further inner circumferentially on the negative terminal 21N. The top plate portion may be arranged in a manner aligned with the positive terminal 21P in the axial Z direction. The top plate portion may be insulated from the negative terminal 21N. Furthermore, if the sealing plate 23 is the negative terminal as described above, a top plate portion that is electrically insulated from the sealing plate 23 may be provided instead of the negative terminal 21N.

[0068] Next, the positive current collector 30P will be explained. For example... Figure 2 , Figure 3 and Figure 5 As shown, the positive current collector 30P is disposed within the housing 20. The positive current collector 30P is disposed on the first direction Z1 side of the wound electrode body 10.

[0069] The positive current collector plate 30P is provided for electrically connecting the positive electrode 11P and the positive terminal 21P. The positive current collector plate 30P is welded to the uncoated portion 111PB of the positive electrode 11P. Therefore, the positive current collector plate 30P is positively charged. The positive current collector plate 30P is also welded to the end of the rivet portion 212 of the positive terminal 21P in the second direction Z2. Therefore, the positive terminal 21P is positively charged.

[0070] An internal gasket 26 is disposed between the positive current collector 30P and the negative terminal 21N. This electrically insulates the positive current collector 30P and the negative terminal 21N from each other. Furthermore, the internal gasket 26 extends to the outer periphery of the positive current collector 30P. Consequently, an internal gasket 26 is also disposed between the positive current collector 30P and the cylindrical wall portion 22. This electrically insulates the positive current collector 30P and the cylindrical wall portion 22 from each other.

[0071] The positive current collector 30P has a generally circular shape. The positive current collector 30P includes a central portion 31P, an outer peripheral portion 32P, multiple spokes 33P, and multiple plates 35P.

[0072] The central portion 31P is located at a position that overlaps with the rivet portion 212 of the positive terminal 21P when viewed from the Z-axis. The positive current collector plate 30P is electrically connected to the positive terminal 21P via the central portion 31P and the housing 20. Specifically, the central portion 31P and the rivet portion 212 of the positive terminal 21P are joined by welding.

[0073] The outer peripheral portion 32P is disposed on the outer periphery of the positive current collector 30P. The outer peripheral portion 32P is located on the outer periphery of the central portion 31P. The outer peripheral portion 32P extends in a ring shape with the central portion 31P as the center. The outer peripheral portion 32P may also contact the uncoated portion 111PB of the positive electrode 11P. However, the outer peripheral portion 32P is not bonded to the uncoated portion 111PB.

[0074] Multiple spokes 33P are spaced apart from each other. The multiple spokes 33P are arranged at equal intervals in the circumferential direction with the central portion 31P as the center. The spokes 33P connect the central portion 31P and the outer peripheral portion 32P. The spokes 33P have a shape in which the width dimension is approximately equal from the central portion 31P to the outer peripheral portion 32P.

[0075] Multiple plates 35P are spaced apart from each other. Multiple plates 35P are arranged at equal intervals in the circumferential direction centered on the central portion 31P. Multiple spokes 33P and multiple plates 35P are arranged in a manner in which spokes 33P and plates 35P are arranged alternately in the circumferential direction centered on the central portion 31P.

[0076] The sheet portion 35P extends from the outer peripheral portion 32P toward the central portion 31P. The sheet portion 35P is connected to the positive electrode 11P. Specifically, the sheet portion 35P is bonded to the uncoated positive electrode portion 111PB of the positive electrode 11P by soldering. Figure 5 The diagram schematically shows the path PP on the positive current collector plate 30P from the joint between the sheet portion 35P and the uncoated positive electrode portion 111PB to the joint between the central portion 31P and the rivet portion 212.

[0077] The sheet portion 35P has a fan-shaped portion 351P and a neck portion 352P. The fan-shaped portion 351P is joined to the uncoated positive electrode portion 111PB of the positive electrode 11P by welding. The tip of the fan-shaped portion 351P faces the central portion 31P. The fan-shaped portion 351P extends towards the outer peripheral edge portion 32P along two adjacent spokes 33P on both sides in the circumferential direction. As a result, the surface area of ​​the fan-shaped portion 351P is relatively large, making welding to the uncoated positive electrode portion 111PB of the positive electrode 11P easier.

[0078] The neck 352P connects the outer peripheral portion 32P and the fan-shaped portion 351P. The neck 352P can also contact the uncoated positive electrode portion 111PB of the positive electrode 11P. However, the neck 352P is not bonded to the uncoated positive electrode portion 111PB of the positive electrode 11P. The circumferential dimension of the neck 352P is smaller than the circumferential dimension of the outer peripheral edge of the fan-shaped portion 351P. Therefore, at the neck 352P, the sheet portion 35P is prone to bending.

[0079] Here, an example of the welding method between the central portion 31P and the rivet portion 212 in this embodiment will be described. First, before welding the central portion 31P and the rivet portion 212, the fan-shaped portion 351P of the plate portion 35P is pre-welded to the uncoated portion 111PB of the positive electrode 11P. Next, a welding device is inserted from the second direction Z2 side of the winding electrode body 10 along the winding axis α of the winding electrode body 10. Then, with the welding device abutting against the central portion 31P from the second direction Z2 side, the central portion 31P and the rivet portion 212 are welded together by the welding device. At this time, the connection portion between the spoke 33P and the central portion 31P, and the connection portion between the spoke 33P and the outer peripheral portion 32P, are significantly deflected on the path PP. As a result, the central portion 31P can be easily displaced relative to the plate portion 35P in the axial Z direction. Therefore, even if the welding device is pressed against the central portion 31P, the bonding between the sheet portion 35P and the uncoated positive electrode portion 111PB can be prevented from being disrupted due to the displacement of the central portion 31P. Furthermore, the connection between the positive electrode current collector 30P and the housing 20 becomes easier.

[0080] Next, the negative current collector 30N will be explained. Figure 7 This is a top view showing the negative current collector in Embodiment 1. Figure 2 , Figure 3 , Figure 6 and Figure 7 As shown, the negative electrode current collector 30N is disposed inside the housing 20. The negative electrode current collector 30N is disposed on one side of the axial direction Z of the wound electrode body 10, that is, the second direction Z2 side.

[0081] The negative current collector plate 30N is provided for electrically connecting the negative electrode 11N and the negative terminal 21N. The negative current collector plate 30N is welded to the uncoated portion 111NB of the negative electrode 11N. Therefore, the negative current collector plate 30N carries a negative charge. The negative current collector plate 30N is joined to the cylindrical wall portion 22 by being tightened together with the outer periphery of the sealing plate 23 and the annular gasket 27 by the tightening portion 22d. Therefore, the negative terminal 21N connected to the cylindrical wall portion 22 carries a negative charge.

[0082] The negative electrode current collector 30N has a generally circular shape. The negative electrode current collector 30N includes a central portion 31N, an outer peripheral portion 32N, a plurality of spokes 33N, a plurality of first plates 34N, and a plurality of second plates 35N. In Embodiment 1, the above-described components included in the negative electrode current collector 30N are illustrated as the central portion (31), outer peripheral portion (32), spokes (33), first plates (34), and second plates (35) in this disclosure.

[0083] The central portion 31N is arranged to overlap with the center of the wound electrode body 10 when viewed from the Z-axis. Specifically, when viewed from the Z-axis, the central portion 31N is located at a position overlapping with the winding axis α. The central portion 31N may also contact the uncoated portion 111NB of the negative electrode 11N. However, the central portion 31N is not coupled to the uncoated portion 111NB.

[0084] A through hole 31Nh is formed in the central portion 31N. When viewed from the axial direction Z, the through hole 31N in the central portion 31N overlaps with the through hole 23h in the sealing plate 23. This facilitates the injection of electrolyte through the through hole 23h. Furthermore, when releasing pressure within the casing 20, it prevents the negative electrode current collector 30N from blocking the through hole 23h in the sealing plate 23. The sealing plug 24 is also inserted through the through hole 31Nh in the central portion 31N.

[0085] The outer peripheral portion 32N is disposed on the outer periphery of the negative electrode current collector 30N. The outer peripheral portion 32N is located on the outer periphery of the central portion 31N. The outer peripheral portion 32N extends in a ring shape with the central portion 31P as the center.

[0086] The negative electrode current collector 30N is electrically connected to the negative terminal 21N via either the outer peripheral portion 32N or the central portion 31N, which is connected to the outer casing 20. In this embodiment, the negative electrode current collector 30N is electrically connected to the negative terminal 21N via the outer peripheral portion 32N, which is connected to the cylindrical wall portion 22. Specifically, the outer peripheral portion 32N is joined to the cylindrical wall portion 22 by being tightened together with the outer periphery of the sealing plate 23 and the annular gasket 27 by the tightening portion 22d. Thus, the outer peripheral portion 32N is electrically connected to the negative terminal 21N connected to the cylindrical wall portion 22.

[0087] The outer peripheral portion 32N has an annular base 321 and a plurality of outermost peripheral portions 322. The annular base 321 extends in a ring shape with the central portion 31N as the center. The annular base 321 is not connected to the cylindrical wall portion 22. That is, the annular base 321 is not tightened to the cylindrical wall portion 22 by the tightening portion 22d.

[0088] Multiple outermost peripheral portions 322 extend outward from the annular base 321. These portions 322 are spaced apart from each other. They are arranged at equal intervals in the circumferential direction centered on the central portion 31P. The portions 322 are connected to the cylindrical wall portion 22. Specifically, the portions 322 are tightened to the cylindrical wall portion 22 by the tightening portion 22d. By connecting the spaced outermost peripheral portions 322 and the cylindrical wall portion 22 through tightening, stress concentration acting on the outer peripheral edge portion 32N can be mitigated.

[0089] Multiple spokes 33N are spaced apart from each other. The multiple spokes 33N are arranged at equal intervals in the circumferential direction centered on the central portion 31N. The spokes 33N connect the central portion 31N and the outer peripheral portion 32N. The spokes 33N have a shape with a width dimension that is approximately equal from the central portion 31N to the outer peripheral portion 32N. The multiple spokes 33N are arranged radially with multiple outermost peripheral portions 322. Therefore, when the spokes 33N flex in the axial direction Z, shear force acting between the annular base 321 and the outermost peripheral portion 322 can be suppressed.

[0090] Multiple first portions 34N are spaced apart from each other. Multiple first portions 34N are arranged at equal intervals in the circumferential direction with the central portion 31N as the center. Multiple first portions 34N are adjacent to two spokes 33N on both sides of the circumferential direction.

[0091] The first portion 34N extends from the central portion 31N toward the outer peripheral portion 32N. The first portion 34N is connected to the negative electrode 11N. Specifically, the first portion 34N is bonded to the uncoated portion 111NB of the negative electrode 11N by soldering. Figure 6 and Figure 7 The diagram schematically illustrates the path on the negative electrode current collector 30N, i.e., the first path PN1, from the junction of the first piece 34N and the uncoated negative electrode portion 111NB to the junction of the outer peripheral portion 32N and the cylindrical wall portion 22. The first piece 34N extends along two adjacent spokes 33N. This results in a relatively large surface area for the first piece 34N, facilitating soldering to the uncoated negative electrode portion 111NB of the negative electrode 11N.

[0092] Multiple second portions 35N are spaced apart from each other. The multiple second portions 35N are arranged at equal intervals in the circumferential direction centered on the central portion 31N. Each of the multiple second portions 35N is adjacent to two spokes 33N on both sides of the circumference. That is, the first portion 34N and the second portion 35N are arranged circumferentially, separated by spokes 33N, centered on the central portion 31N.

[0093] The second piece 35N extends from the outer periphery 32N toward the center 31N. The second piece 35N is connected to the negative electrode 11N. The second piece 35N and the uncoated negative electrode portion 111NB of the negative electrode 11N are joined by soldering. Figure 6 and Figure 7 The diagram schematically shows the path on the negative electrode current collector 30N, namely the second path PN2, from the joint between the second piece 35N and the uncoated negative electrode portion 111NB to the joint between the outer peripheral portion 32 and the cylindrical wall portion 22. Alternatively, the second piece 35N may be joined to the uncoated negative electrode portion 111NB without soldering.

[0094] The second portion 35N has a fan-shaped portion 351N and a neck 352N. The fan-shaped portion 351N is joined to the uncoated negative electrode portion 111NB of the negative electrode 11N by welding. The tip of the fan-shaped portion 351N faces the central portion 31N. The fan-shaped portion 351N extends along two adjacent spokes 33N on both sides in the circumferential direction. As a result, the surface area of ​​the fan-shaped portion 351N is relatively large, making welding to the uncoated negative electrode portion 111NB of the negative electrode 11N easier.

[0095] The neck 352N connects the outer peripheral portion 32N and the fan-shaped portion 351N. The neck 352N can also contact the uncoated negative electrode portion 111NB of the negative electrode 11N. However, the neck 352N is not bonded to the uncoated negative electrode portion 111NB of the negative electrode 11N. The circumferential dimension of the neck 352N is smaller than the circumferential dimension of the outer peripheral edge of the fan-shaped portion 351N. Therefore, the second piece 35N is prone to bending at the neck 352N.

[0096] Here, an example of a tightening-based joining method for the outermost peripheral portion 322 of the outer peripheral portion 32N and the cylindrical wall portion 22 will be described. First, before the outermost peripheral portion 322 and the cylindrical wall portion 22 are joined by tightening, the fan-shaped portions 351N of the first piece 34N and the second piece 35N are pre-welded to the uncoated negative electrode portion 111NB of the negative electrode 11N. Afterward, the cylindrical wall portion 22 is tightened to form a tightened portion 22d. At this time, on the first path PN1, the connection portion between the spoke 33N and the central portion 31N, and the connection portion between the spoke 33N and the outer peripheral portion 32N, are significantly deflected. As a result, the outermost peripheral portion 322 can be easily displaced relative to the first piece 34N in the axial Z direction. Therefore, when the outer peripheral portion 32N is connected to the cylindrical wall portion 22, even if the outer peripheral portion 32N is displaced in the axial direction Z, the bonding between the first piece portion 34N and the uncoated negative electrode portion 111NB can be prevented from being disrupted. Furthermore, the connection between the negative electrode current collector 30N and the housing 20 becomes easier.

[0097] On the other hand, the second path PN2 is shorter than the first path PN1. Therefore, when the negative current collector 30N is energized, the second path PN2 becomes the main conductive path. The shorter second path PN2 reduces the heat generated during energization.

[0098] As described above, the energy storage unit 1 according to Embodiment 1 of this disclosure includes a wound electrode body 10, a housing 20, and a current collector 30. The wound electrode body 10 includes a first electrode 11A and a second electrode 11B. The housing 20 houses the wound electrode body 10 and includes a first external terminal 21A. The current collector 30 is disposed within the housing 20 on one side of the wound electrode body 10 along the axial direction Z. The current collector 30 is provided for electrically connecting the first electrode 11A and the first external terminal 21A. The current collector 30 includes a central portion 31, an outer peripheral portion 32, spokes 33, a first sheet portion 34, and a second sheet portion 35. The central portion 31 is disposed such that it overlaps with the center of the wound electrode body 10 when viewed from the axial direction Z. The outer peripheral portion 32 is located on the outer periphery of the central portion 31. The current collector 30 is electrically connected to the first external terminal 21A by connecting either the outer peripheral portion 32 or the central portion 31 to the housing 20. Spokes 33 connect the central portion 31 and the outer peripheral portion 32. A first plate portion 34 extends from the central portion 31 toward the outer peripheral portion 32 and is connected to the first electrode 11A. A second plate portion 35 extends from the outer peripheral portion 32 toward the central portion 31 and is connected to the first electrode 11A.

[0099] Based on the above configuration, the connection between the current collector 30 and the housing 20 becomes easier, and the heat generation of the current collector 30 can be suppressed.

[0100] Furthermore, from another perspective, with the above-described configuration, the energy storage unit 1 can generate moderate heat when energized. As in Embodiment 1 of this disclosure, for example, when the outer peripheral portion 32 is connected to the outer casing 20, the path PN1 on the current collector plate 30, which is connected in the order of the first plate 34, the central portion 31, the spokes 33, and the outer peripheral portion 32, is relatively long. Therefore, when the energy storage unit 1 is energized, the current collector plate 30 generates a relatively large amount of heat along this path PN1. On the other hand, the path on the current collector plate 30, which consists only of the second plate 35 and the outer peripheral portion 32, is relatively short. Therefore, the heat generated along this path PN2 when energized is relatively small. Thus, it is possible to provide an energy storage unit 1 that generates moderate heat when energized.

[0101] Furthermore, in Embodiment 1 of this disclosure, the first piece 34 and the second piece 35 are arranged circumferentially with the central piece 31 as the center, separated by spokes 33.

[0102] According to the above configuration, the long conductive path (the first path PN1 in this embodiment) on the current collector 30, which generates more heat when energized, and the short path (the second path PN2 in this embodiment) on the current collector 30, which generates less heat, are arranged circumferentially opposite to each other. As a result, the deviation in the distribution of heat generated by the current collector 30 when energized can be reduced circumferentially.

[0103] Furthermore, in Embodiment 1 of this disclosure, the first piece 34 and the second piece 35 are welded to the first electrode 11A.

[0104] According to the above configuration, the first plate portion 34 and the second plate portion 35 are reliably fixedly connected by the first electrode 11A. Furthermore, the conductive path via the first plate portion 34 (the first path PN1 in this embodiment) and the conductive path via the second plate portion 35 (the second path PN2 in this embodiment) in the current collector plate 30 are formed more reliably.

[0105] Furthermore, in Embodiment 1 of this disclosure, the housing 20 includes a cylindrical wall portion 22 that covers the entire outer periphery of the coiled electrode body 10. The current collector 30 is electrically connected to the first external terminal 21A via the outer peripheral portion 32 connected to the cylindrical wall portion 22.

[0106] According to the above configuration, the conductive path from the current collector 30 to the first external terminal 21A includes a cylindrical wall portion 22 with a relatively large outer surface area. This allows heat generated in the conductive path during energization to be easily released from the outer surface of the cylindrical wall portion 22.

[0107] (Implementation Method 2)

[0108] Next, the energy storage unit according to Embodiment 2 of this disclosure will be described. In Embodiment 2 of this disclosure, the configuration of the first and second portions of the negative electrode current collector is different from that in Embodiment 1 of this disclosure. Therefore, the same configuration and effects as in Embodiment 1 of this disclosure will not be described again.

[0109] Figure 8 This is a cross-sectional view showing the energy storage unit according to Embodiment 2. Figure 9 This is a top view showing the negative current collector in Embodiment 2.

[0110] like Figure 8 and Figure 9 As shown, in the energy storage unit 1a according to Embodiment 2 of this disclosure, the first piece 34a and the second piece 35a are arranged radially with the central piece 31 as the center.

[0111] Based on the above configuration, the first piece 34a and the second piece 35a can be compactly arranged. Therefore, for example, compared to Embodiment 1, the number of the first piece 34a and the number of the second piece 35a increase.

[0112] Furthermore, the multiple spokes 33 and the multiple first plates 34a are arranged in a manner in which the spokes 33 and the first plates 34a are alternately arranged in a circumferential direction centered on the central portion 31. The multiple spokes 33 and the multiple second plates 35a are arranged in a manner in a manner in which the spokes 33 and the second plates 35a are alternately arranged in a circumferential direction centered on the central portion 31.

[0113] (Implementation Method 3)

[0114] Next, the energy storage unit according to Embodiment 3 of this disclosure will be described. In Embodiment 3 of this disclosure, the current collector is exemplified by a positive current collector 30P, which is the main difference from Embodiment 1 of this disclosure. Therefore, the same configuration and effects as Embodiment 3 of this disclosure will not be described again.

[0115] Figure 10 This is a cross-sectional view of the energy storage unit involved in Embodiment 3. Figure 11 This is another cross-sectional view of the energy storage unit involved in Embodiment 3. Figure 12 This is an exploded perspective view showing the energy storage unit involved in Embodiment 3. Figure 13 This is an exploded perspective view showing another energy storage unit according to Embodiment 3.

[0116] like Figures 10-13 As shown, in the energy storage unit 1b according to Embodiment 3 of this disclosure, the first electrode (11Ab) is exemplified as the positive electrode 11Pb, and the second electrode (11Ab) is exemplified as the negative electrode 11Nb. Furthermore, the first external terminal (21Ab) is exemplified as the positive terminal 21Pb, and the second external terminal (21Bb) is exemplified as the negative terminal 21Nb.

[0117] First, the positive current collector 30Pb in this embodiment will be explained. Figure 14 This is a top view showing the positive current collector in embodiment 3. (Example) Figures 10-12 and Figure 14 As shown, the positive electrode current collector 30Pb is exemplified as the current collector plate (30b) in this disclosure. The central portion (31P), the outer peripheral portion (32P), the spokes (33P), the first plate portion (34Pb), and the second plate portion (35Pb) included in the positive electrode current collector 30P are respectively exemplified as the central portion (31P), the outer peripheral portion (32P), the spokes (33P), the first plate portion (34Pb), and the second plate portion (35Pb) included in the positive electrode current collector 30P.

[0118] In embodiment 3, the positive current collector 30P includes a plurality of first portions 34Pb and a plurality of second portions 35Pb.

[0119] Multiple first segments 34Pb are spaced apart from each other. Multiple first segments 34Pb are arranged at equal intervals in the circumferential direction centered on the central segment 31P. Multiple first segments 34Pb are each adjacent to two spokes 33P on both sides of the circumferential direction.

[0120] The first portion 34Pb extends from the central portion 31P toward the outer peripheral portion 32P. The first portion 34Pb is connected to the positive electrode 11P. Specifically, the first portion 34Pb is bonded to the uncoated portion 111PB of the positive electrode 11P by welding. Figure 14 The diagram schematically illustrates the path on the positive electrode current collector 30Pb, namely the first path PP1b, from the junction of the first piece 34Pb and the uncoated positive electrode portion 111PB to the junction of the central portion 31P and the rivet portion 212. The first piece 34Pb extends along two adjacent spokes 33P. This results in a relatively large surface area for the first piece 34Pb, facilitating welding to the uncoated positive electrode portion 111PB of the positive electrode 11P. Furthermore, the first piece 34Pb can also be joined without welding to the uncoated positive electrode portion 111PB.

[0121] Multiple second portions 35Pb are spaced apart from each other. These multiple second portions 35Pb are arranged at equal intervals in the circumferential direction centered on the central portion 31P. Each of the multiple second portions 35Pb is adjacent to two spokes 33P on each side of the circumference. That is, the first portion 34Pb and the second portion 35Pb are arranged circumferentially, separated by spokes 33P, centered on the central portion 31P.

[0122] The second portion 35Pb extends from the outer periphery 32P toward the central portion 31P. The second portion 35Pb is connected to the positive electrode 11P. The second portion 35Pb is bonded to the uncoated portion 111PB of the positive electrode 11P by welding. Figure 14 The diagram schematically shows the path on the positive current collector plate 30P, namely the second path PP2b, from the joint between the second piece 35Pb and the uncoated positive electrode portion 111PB to the joint between the central portion 31P and the rivet portion 212.

[0123] The second portion 35Pb has a fan-shaped portion 351P and a neck 352P. The fan-shaped portion 351P is joined to the uncoated positive electrode portion 111PB of the positive electrode 11P by welding. The tip of the fan-shaped portion 351P faces the central portion 31P. The fan-shaped portion 351P extends along two adjacent spokes 33P on both sides in the circumferential direction. As a result, the surface area of ​​the fan-shaped portion 351P is relatively large, making welding to the uncoated positive electrode portion 111PB of the positive electrode 11P easier.

[0124] The neck 352P connects the outer peripheral portion 32P and the fan-shaped portion 351P. The neck 352P can also contact the uncoated positive electrode portion 111PB of the positive electrode 11P. However, the neck 352P is not bonded to the uncoated positive electrode portion 111PB of the positive electrode 11P. The circumferential dimension of the neck 352P is smaller than the circumferential dimension of the outer peripheral edge of the fan-shaped portion 351P. Therefore, at the neck 352P, the second piece 35Pb is prone to bending.

[0125] Here, an example of the welding method between the central portion 31P and the rivet portion 212 in this embodiment will be described. First, before welding the central portion 31P and the rivet portion 212, the fan-shaped portions 351P of the first piece 34Pb and the second piece 35Pb are pre-welded to the uncoated portion 111PB of the positive electrode 11P. Next, a welding device is inserted from the second direction Z2 side of the winding electrode body 10 along the winding axis α of the winding electrode body 10. Then, with the welding device abutting against the central portion 31P from the second direction Z2 side, the central portion 31P and the rivet portion 212 are welded together by the welding device. At this time, on the second path PP2b, the connection portion between the spoke 33P and the central portion 31P and the connection portion between the spoke 33P and the outer peripheral portion 32P are significantly deflected. As a result, the central portion 31P can be easily displaced in the axial Z direction relative to the second piece 35Pb. Therefore, even if the welding device is pressed against the central portion 31P, the bonding between the second portion 35Pb and the uncoated positive electrode portion 111PB can be prevented from being disrupted due to the displacement of the central portion 31P. Furthermore, the connection between the positive electrode current collector 30Pb and the housing 20 becomes easier.

[0126] On the other hand, the first path PP1b is shorter than the second path PP2b. Therefore, when the positive current collector 30Pb is energized, the first path PP1b becomes the main conductive path. The shorter first path PP1b can reduce the heat generated during energization.

[0127] Next, the negative current collector 30Nb in Embodiment 3 will be described. For example... Figure 10 , Figure 11 and Figure 13 As shown, in Embodiment 3, the negative current collector 30Nb includes a plurality of plates 34Nb.

[0128] Multiple plates 34Nb are spaced apart from each other. Multiple plates 34Nb are arranged at equal intervals in the circumferential direction centered on the central portion 31N. Multiple spokes 33N and multiple plates 34Nb are arranged in a manner in which spokes 33N and plates 34Nb are arranged alternately in the circumferential direction centered on the central portion 31N.

[0129] The sheet portion 34Nb extends from the central portion 31N toward the outer peripheral portion 32N. The sheet portion 34Nb is connected to the negative electrode 11N. Specifically, the sheet portion 34Nb is bonded to the uncoated negative electrode portion 111NB of the negative electrode 11N by soldering. Figure 13The diagram schematically illustrates the path, or path PNb, on the negative electrode current collector plate 30N from the junction of the sheet portion 34Nb and the uncoated negative electrode portion 111NB to the junction of the outer peripheral portion 32N and the cylindrical wall portion 22. The sheet portion 34Nb extends along two adjacent spokes 33N. This results in a relatively large surface area for the sheet portion 34Nb, facilitating soldering to the uncoated negative electrode portion 111NB of the negative electrode 11N.

[0130] Here, an example of a tightening-based joining method for the outermost peripheral portion 322 of the outer peripheral portion 32N and the cylindrical wall portion 22 will be described. First, before the outermost peripheral portion 322 and the cylindrical wall portion 22 are joined by tightening, the sheet portion 34Nb is pre-welded to the uncoated negative electrode portion 111NB of the negative electrode 11N. Afterward, the cylindrical wall portion 22 is tightened to form a tightened portion 22d. At this time, the connection portion between the spoke 33N and the central portion 31N and the connection portion between the spoke 33N and the outer peripheral portion 32N on the path PNb is significantly deflected. As a result, the outermost peripheral portion 322 can easily displace relative to the sheet portion 34Nb in the axial Z direction. Therefore, when the outer peripheral portion 32N is joined to the cylindrical wall portion 22, even if the outer peripheral portion 32N displaces in the axial Z direction, the joint between the sheet portion 34Nb and the uncoated negative electrode portion 111NB can be prevented from being disrupted. Furthermore, the connection between the negative current collector 30Nb and the housing 20 becomes easier.

[0131] As described above, the energy storage unit 1b according to Embodiment 3 of this disclosure includes a wound electrode body 10, a housing 20, and a current collector plate 30b. The wound electrode body 10 includes a first electrode 11Ab and a second electrode 11B. The housing 20 houses the wound electrode body 10 and includes a first external terminal 21Ab. The current collector plate 30b is disposed within the housing 20 on one side of the wound electrode body 10 along the axial direction Z. The current collector plate 30b is provided for electrically connecting the first electrode 11Ab and the first external terminal 21Ab. The current collector plate 30b includes a central portion 31, an outer peripheral portion 32, spokes 33, a first sheet portion 34b, and a second sheet portion 35b. The central portion 31 is disposed such that it overlaps with the center of the wound electrode body 10 when viewed from the axial direction Z. The outer peripheral portion 32 is located on the outer periphery of the central portion 31. The current collector plate 30b is electrically connected to the first external terminal 21Ab via either the outer peripheral portion 32 or the central portion 31 to the housing 20. Spokes 33 connect the central portion 31 and the outer peripheral portion 32. A first plate portion 34b extends from the central portion 31 toward the outer peripheral portion 32 and is connected to the first electrode 11Ab. A second plate portion 35b extends from the outer peripheral portion 32 toward the central portion 31 and is connected to the first electrode 11Ab.

[0132] Based on the above configuration, the connection between the current collector 30b and the housing 20 becomes easier, and the heat generation of the current collector 30b can be suppressed.

[0133] Furthermore, from another perspective, with the above-described configuration, the energy storage unit 1b can generate moderate heat when energized. As in Embodiment 3 of this disclosure, for example, when the central portion 31 is connected to the outer casing 20, the path PP2b on the current collector plate 30b, which is connected in the order of the second piece 35b, the outer peripheral portion 32, the spokes 33, and the central portion 31, is relatively long. Therefore, when the energy storage unit 1b is energized, the current collector plate 30b generates a relatively large amount of heat along this path PP2b. On the other hand, the path PP1b on the current collector plate 30b, which consists only of the first piece 34b and the central portion 31, is relatively short. Therefore, the heat generated along this path PP1b when energized is relatively small. Thus, it is possible to provide an energy storage unit 1b that generates moderate heat when energized.

[0134] Furthermore, in Embodiment 3 of this disclosure, the first piece 34b and the second piece 35b are arranged circumferentially with the central piece 31 as the center, separated by spokes 33.

[0135] According to the above configuration, the long conductive path (the second path PP2b in this embodiment) on the current collector 30b, which generates more heat when energized, and the short path (the first path PP1b in this embodiment) on the current collector 30b, which generates less heat, are arranged circumferentially opposite to each other. As a result, the deviation in the distribution of heat generated by the current collector 30b when energized can be reduced circumferentially.

[0136] Furthermore, in Embodiment 3 of this disclosure, the first piece 34b and the second piece 35b are welded to the first electrode 11Ab.

[0137] According to the above configuration, the first plate portion 34b and the second plate portion 35b are reliably fixedly connected by the first electrode 11Ab. Furthermore, the conductive path via the first plate portion 34b (the first path PP1b in this embodiment) and the conductive path via the second plate portion 35b (the second path PP2b in this embodiment) in the current collector plate 30b are formed more reliably.

[0138] Furthermore, in Embodiment 3 of this disclosure, the first external terminal 21Ab is located at a position that overlaps with the central portion 31 when viewed from the Z-axis. Additionally, the current collector 30b is electrically connected to the first external terminal 21Ab via the central portion 31, which is connected to the housing 20.

[0139] According to the above configuration, the conductive path from the current collector 30b to the first external terminal 21Ab can be shortened, and the heat generation on the conductive path can be suppressed.

[0140] (Implementation Method 4)

[0141] Next, the energy storage unit according to Embodiment 4 of this disclosure will be described. In Embodiment 4 of this disclosure, the first and second portions of the positive current collector plate are different from those in Embodiment 3 of this disclosure. Therefore, the same configuration and effects as in Embodiment 3 of this disclosure will not be described again.

[0142] Figure 15 This is a cross-sectional view showing the energy storage unit according to Embodiment 4. Figure 16 This is a top view showing the positive current collector in embodiment 4.

[0143] like Figure 15 and Figure 16 As shown, in the energy storage unit 1c according to Embodiment 4 of this disclosure, the first piece 34c and the second piece 35c are arranged radially with the central piece 31 as the center.

[0144] Based on the above configuration, the first piece 34c and the second piece 35c can be compactly arranged. Therefore, for example, compared to Embodiment 3, the number of the first piece 34c and the number of the second piece 35c are increased.

[0145] Furthermore, the multiple spokes 33 and the multiple first plates 34c are arranged in a manner in which the spokes 33 and the first plates 34c are alternately arranged in a circumferential direction centered on the central portion 31. The multiple spokes 33 and the multiple second plates 35c are arranged in a manner in a manner in which the spokes 33 and the second plates 35c are alternately arranged in a circumferential direction centered on the central portion 31.

[0146] (Implementation Method 5)

[0147] Next, the energy storage unit according to Embodiment 5 of this disclosure will be described. Embodiment 5 of this disclosure differs from the energy storage unit 1b according to Embodiment 3 of this disclosure in that it does not include a negative current collector. Therefore, the same configuration and effects as Embodiment 3 of this disclosure will not be described again.

[0148] Figure 17 This is a cross-sectional view of the energy storage unit according to Embodiment 5. Figure 18 This is an exploded perspective view showing the energy storage unit according to Embodiment 5.

[0149] like Figure 17 and Figure 18 As shown, in the energy storage unit 1d according to Embodiment 5, the outer casing 20 does not include annular gaskets.

[0150] In this embodiment, the outer periphery of the sealing plate 23d is connected to the cylindrical wall portion 22 by welding such as laser welding. Therefore, in this embodiment, no tightening portion is provided in the cylindrical wall portion 22.

[0151] In this embodiment, the sealing plate 23d is provided for electrically connecting the negative electrode 11N and the negative terminal 21N. The sealing plate 23d is welded to the uncoated portion 111NB of the negative electrode 11N. Therefore, the sealing plate 23d carries a negative charge. Additionally, the negative terminal 21N connected to the cylindrical wall portion 22 carries a negative charge. Alternatively, the sealing plate 23d may also be the negative terminal.

[0152] The sealing plate 23d has an annular protrusion 231, multiple radial protrusions 232, and multiple welding portions 233. When viewed from the axial direction Z, the annular protrusion 231 extends in a ring shape around the winding axis α of the winding electrode body 10. The annular protrusion 231 protrudes towards the first direction Z1. That is, the annular protrusion 231 protrudes towards the winding electrode body 10. The annular protrusion 231 contacts the uncoated portion 111NB of the negative electrode 11N.

[0153] When viewed from the axial direction Z, the plurality of radial protrusions 232 are arranged in a spaced-apart manner in the circumferential direction centered on the winding axis α of the winding electrode body 10. The plurality of radial protrusions 232 are arranged at equal intervals in this circumferential direction.

[0154] Multiple radial protrusions 232 extend radially about the winding axis α of the winding electrode body 10. The radial protrusions 232 are connected to the annular protrusions 231.

[0155] The radial protrusion 232 protrudes toward the first direction Z1. That is, the radial protrusion 232 protrudes toward the wound electrode body 10. The radial protrusion 232 contacts the uncoated portion 111NB of the negative electrode 11N.

[0156] Multiple weld portions 233 are portions of the sealing plate 23d joined to the uncoated negative electrode portion 111NB by welding. Multiple weld portions 233 are formed in the annular ridge portion 231. In the annular ridge portion 231, the multiple weld portions 233 are formed in a manner extending circumferentially. Multiple weld portions 233 are also formed in multiple radial ridge portions 232. In the radial ridge portions 232, the weld portions 233 are formed in a manner extending radially. The annular ridge portion 231 and the multiple radial ridge portions 232 can be thinner than other portions of the sealing plate 23d. Therefore, the formation of the weld portions 233 becomes easier.

[0157] In the above description of the embodiments, the components that can be combined can also be combined with each other. For example, the positive current collector in one embodiment can be combined with the negative current collector in other embodiments.

[0158] While embodiments of the invention have been described, it should be understood that the embodiments disclosed herein are illustrative in all respects and not restrictive. The scope of the invention is defined by the claims and is intended to include all modifications within the meaning and scope equivalent to the claims.

Claims

1. An energy storage unit, comprising: A wound electrode body, comprising a first electrode and a second electrode; A housing that contains the wound electrode body; and A current collector is disposed within the housing on one side of the wound electrode body along its axial direction. The outer casing also includes a cylindrical wall, an annular gasket, and a sealing plate. The cylindrical wall portion is located on the outer periphery of the wound electrode body. A constricting portion is formed at the end of the cylindrical wall portion. The annular gasket is located between the tightening portion and the outer periphery of the sealing plate. The current collector plate includes a central portion, an outer peripheral portion, spokes, and a sheet portion. A through hole is formed in the central part. The outer peripheral portion is located on the outer periphery of the central portion. The outer peripheral portion is connected to the tightening portion. The spokes connect the central portion to the outer peripheral portion. The plate extends from the outer periphery toward the central portion when viewed from the axial direction and is connected to the first electrode. The spokes are bent such that the distance between the spokes and the sealing plate in the axial direction is less than the distance between the plate and the sealing plate.

2. The energy storage unit according to claim 1, The outer peripheral portion includes an annular base and multiple outermost peripheral portions. The plurality of outermost portions extend from the annular base toward the outer periphery. The plurality of outermost peripheral portions are separated from each other. The plurality of outermost peripheral portions are connected to the tightening portion.

3. The energy storage unit according to claim 1 or 2, The plate portion includes a fan-shaped portion and a neck. The fan-shaped portion is joined to the first electrode by welding. The neck connects the outer peripheral portion to the fan-shaped portion. The circumferential dimension of the neck of the outer peripheral portion is smaller than the circumferential dimension of the fan-shaped portion.

4. The energy storage unit according to claim 1 or 2, The sheet portion includes a neck connected to the outer peripheral portion and an inner peripheral portion located on the opposite side of the neck. The inner periphery extends in an arc shape toward the neck.

5. The energy storage unit according to claim 1 or 2, A through hole is formed in the sealing plate. The housing also includes a sealing plug that seals the through-hole formed in the sealing plate. The inner space of the through hole formed in the central part and the inner space of the through hole formed in the sealing plate are arranged in the axial direction.

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