Electricity storage unit

Abstract

The present disclosure relates to an electricity storage cell in which a wound electrode body includes a first electrode and a second electrode. The first collector member is connected to the first electrode. The second collector member is connected to the second electrode. The cover includes a first external terminal and a second external terminal. The first external terminal is disposed so as to overlap the radial center of the wound electrode body when viewed from the axial direction. The second external terminal is fixed to the housing main body. The first collector member is connected to the first external terminal. The second current collection member is disposed between the housing main body and the second external terminal. The second current collector member is joined to the second external terminal by being fixed to the housing main body together with the second external terminal.

Description

Technical Field

[0001] The present disclosure relates to a power storage unit. Background Art

[0002] In Japanese Patent No. 3322321, a non-aqueous electrolyte secondary battery is disclosed as a power storage unit. In this non-aqueous electrolyte secondary battery, a negative electrode and a positive electrode are wound with a porous separator interposed therebetween and inserted into a cylindrical container. Leads are taken out from the positive electrode and the negative electrode. The cylindrical container is made of stainless steel. A container lid is welded to the opening of the container at the peripheral portion. A positive electrode terminal and a negative electrode terminal are provided at a part of the container lid. Summary of the Utility Model

[0003] In the case where both a positive electrode terminal and a negative electrode terminal are provided on the lid as in the power storage unit disclosed in Japanese Patent No. 3322321, the distance between the lead of the positive electrode and the lead of the negative electrode in the container is relatively close. Thus, for example, there is a possibility that the leads contact each other and cause a short circuit.

[0004] The present disclosure has been made in view of the above problems, and an object thereof is to provide a power storage unit capable of suppressing a short circuit inside the unit housing.

[0005] The power storage unit according to the first aspect of the present disclosure includes a wound electrode body, a unit housing, a first current collector, and a second current collector. The wound electrode body includes a first electrode and a second electrode. The unit housing houses the wound electrode body. The first current collector is connected to the first electrode. The second current collector is connected to the second electrode. The unit housing includes a housing main body and a lid. The housing main body has an opening portion that opens on one side in the axial direction of the wound electrode body when viewed from the wound electrode body. The lid closes the opening portion of the housing main body. The lid includes a first external terminal and a second external terminal. The first external terminal is arranged to overlap with the radial center of the wound electrode body when viewed from the above axial direction. The second external terminal is fixed to the housing main body. The first current collector is arranged on the above one side in the axial direction of the wound electrode body. The first current collector is connected to the first external terminal. The second current collector is arranged on the above one side in the axial direction of the wound electrode body. The second current collector is arranged between the housing main body and the second external terminal. The second current collector is joined to the second external terminal by being fixed to the housing main body together with the second external terminal.

[0006] According to the above configuration, the second external terminal and the second current collector are joined to each other at a position far from the first current collector connected to the first external terminal. Therefore, a short circuit between the first current collector and the second current collector can be suppressed. Therefore, according to the above configuration, a power storage unit capable of suppressing a short circuit inside the unit housing can be provided.

[0007] The electricity storage unit according to the second aspect of the present disclosure includes a wound electrode body, a unit housing, a first current collector member, and a second current collector member. The wound electrode body includes a first electrode and a second electrode. The unit housing houses the wound electrode body. The first current collector member is connected to the first electrode. The second current collector member is connected to the second electrode. The unit housing includes a housing main body and a lid. The housing main body has conductivity and has an opening portion that opens on one side in the axial direction of the wound electrode body when viewed from the wound electrode body. The lid closes the opening portion of the housing main body. The lid includes a first external terminal and a second external terminal. The first external terminal is arranged to overlap the radial center of the wound electrode body when viewed from the above-mentioned axial direction. The second external terminal is directly joined to the housing main body. The first current collector member is arranged on the above-mentioned one side in the axial direction of the wound electrode body. The first current collector member is connected to the first external terminal. The second current collector member is arranged on the other side in the axial direction of the wound electrode body. The second current collector member is directly connected to the housing main body.

[0008] According to the above configuration, at a position far from the first current collector member connected to the first external terminal, the second external terminal and the second current collector member are electrically connected to each other via the housing main body. Therefore, a short circuit between the first current collector member and the second current collector member can be suppressed. Therefore, according to the above configuration, an electricity storage unit in which a short circuit inside the unit housing is suppressed can be provided.

[0009] According to the present disclosure, a short circuit inside the unit housing can be suppressed. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Hereinafter, the features, advantages, and technical and industrial significance of the exemplary embodiments of the present utility model will be described with reference to the drawings, and the same reference numerals in the drawings denote the same elements.

[0011] Figure 1 is a perspective view showing the electricity storage unit of Embodiment 1;

[0012] Figure 2 is a cross-sectional view of the electricity storage unit viewed in the arrow direction along line II-II Figure 1 of;

[0013] Figure 3 is a cross-sectional view showing the electricity storage unit of Embodiment 2. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0014] Hereinafter, the electricity storage unit of each embodiment of the present disclosure will be described with reference to the drawings. The same or corresponding parts in the drawings are denoted by the same reference numerals, and the description thereof will not be repeated.

[0015] Embodiment 1

[0016] Figure 1 is a perspective view showing the electricity storage unit of Embodiment 1. Figure 2Viewed along the arrow direction of line II-II Figure 1 Cross-sectional view of the power storage unit

[0017] As Figure 1 and Figure 2 shown, the power storage unit 1 of Embodiment 1 is a cylindrical battery. The power storage unit 1 includes a wound electrode body 10, a unit housing 20, a first current collector member 30, and a second current collector member 40.

[0018] First, the wound electrode body 10 will be described. As Figure 2 shown, the wound electrode body 10 includes a positive electrode 11P, a negative electrode 11N, and a separator 12. In the wound electrode body 10, the positive electrode 11P, the negative electrode 11N, and the separator 12 are wound around the periphery of the winding axis α.

[0019] In Embodiment 1, the positive electrode 11P is exemplified as the first electrode in the present disclosure. In Embodiment 1, the negative electrode 11N is exemplified as the second electrode in the present disclosure. However, the first electrode may also be the negative electrode. The second electrode may also be the positive electrode.

[0020] The positive electrode 11P and the negative electrode 11N have a sheet-like outer shape. The wound electrode body 10 is composed of a plate group formed by winding the positive electrode 11P and the negative electrode 11N with the separator 12 interposed therebetween.

[0021] The separator 12 is provided between the positive electrode 11P and the negative electrode 11N. The separator 12 allows ions (such as lithium ions) to travel back and forth between the positive electrode 11P (positive electrode active material) and the negative electrode 11N (negative electrode active material) and isolates the positive electrode 11P and the negative electrode 11N.

[0022] The positive electrode 11P includes a positive electrode current collector foil 111P and a positive electrode mixture layer 112P. The positive electrode current collector foil 111P is formed of, for example, aluminum or the like.

[0023] The positive electrode mixture layer 112P is coated on both sides in the radial direction of the positive electrode current collector foil 111P. The positive electrode mixture layer 112P is in close contact with the separator 12. The positive electrode mixture layer 112P is formed by coating a positive electrode paste on the surface of the positive electrode current collector foil 111P and drying it. The positive electrode paste is a paste prepared by kneading the materials (positive electrode active material, binder, etc.) of the positive electrode mixture layer 112P with a solvent. The thickness of the positive electrode mixture layer 112P is, for example, 0.1 μm or more and 1000 μm or less.

[0024] The negative electrode 11N includes a negative electrode current collector foil 111N and a negative electrode mixture layer 112N. The negative electrode current collector foil 111N is formed of, for example, copper or the like.

[0025] The negative electrode mixture layer 112N is coated on both sides in the radial direction of the negative electrode current collector foil 111N. The negative electrode mixture layer 112N is in close contact with the separator 12. The negative electrode mixture layer 112N is formed by coating a negative electrode paste on the surface of the negative electrode current collector foil 111N and drying it. The negative electrode paste is a paste prepared by kneading the materials of the negative electrode mixture layer 112N (negative electrode active material, binder, etc.) with a solvent. The thickness of the negative electrode mixture layer 112N is, for example, 0.1 μm or more and 1000 μm or less.

[0026] Next, the unit case 20 will be described. As Figure 1 and Figure 2 shown, the unit case 20 houses the wound electrode body 10. The unit case 20 includes a case main body 21 and a lid 22.

[0027] The case main body 21 has an opening 211 that opens on one side (the first direction Z1 side) in the axial direction Z of the wound electrode body 10 when viewed from the wound electrode body 10. Specifically, the opening 211 opens on the first direction Z1 side of the case main body 21. The case main body 21 has a bottomed cylindrical shape.

[0028] The case main body 21 further includes a tightening portion 212 formed by tightening (chiseling) the end portion on one side (the first direction Z1 side) of the wound electrode body 10. The tightening portion 212 extends annularly along the opening 211.

[0029] The case main body 21 further includes a cylindrical wall portion 213, a bottom portion 214, and a sealing layer 215.

[0030] The cylindrical wall portion 213 is provided so as to cover the outer peripheral side of the wound electrode body 10. The cylindrical wall portion 213 covers the entire outer peripheral side of the wound electrode body 10. The cylindrical wall portion 213 has a cylindrical shape. The cylindrical wall portion 213 may also have a rectangular cylindrical shape. When viewed from the tightening portion 212, the cylindrical wall portion 213 is located on the second direction Z2 side in the axial direction Z. The cylindrical wall portion 213 is integrally formed with the tightening portion 212.

[0031] When viewed from the wound electrode body 10, the bottom portion 214 is disposed along the second direction Z2 side in the axial direction Z. The bottom portion 214 is connected to the end portion on the second direction Z2 side of the cylindrical wall portion 213. In the present embodiment, the bottom portion 214 is integrally formed with the cylindrical wall portion 213. The bottom portion 214 may also be formed as a member separate from the cylindrical wall portion 213. At this time, the outer peripheral edge of the bottom portion 214 may be joined to the cylindrical wall portion 213 by laser welding or the like.

[0032] A through-hole 214h is formed in the bottom 214. The through-hole 214h may also be provided for injecting an electrolyte (not shown) housed in the unit case 20. A sealing plug 216 is inserted through the through-hole 214h in the bottom 214. Thus, the sealing plug 216 is fixed to the bottom 214. The sealing plug 216 and the through-hole 214h can function as a pressure relief valve for releasing the pressure inside the unit case 20 when the pressure inside the unit case 20 becomes too high.

[0033] The tightening portion 212, the cylindrical wall portion 213, and the bottom 214 are conductive. The tightening portion 212, the cylindrical wall portion 213, and the bottom 214 are formed of aluminum or an aluminum alloy, copper, or stainless steel, etc.

[0034] The sealing layer 215 is disposed radially inside the tightening portion 212. In the present embodiment, the sealing layer 215 forms an opening 211. The sealing layer 215 extends along the tightening portion 212. The sealing layer 215 has an annular shape. The sealing layer 215 has electrical insulation properties.

[0035] The lid 22 closes the opening 211 of the case main body 21. The lid 22 includes a positive electrode external terminal 221P, a negative electrode external terminal 221N, and an insulating member 222. In Embodiment 1, the positive electrode external terminal 221P is illustrated as the first external terminal in the present disclosure. In Embodiment 1, the negative electrode external terminal 221N is illustrated as the second external terminal in the present disclosure. However, the first external terminal may be the negative electrode external terminal, and the second external terminal may be the positive electrode external terminal.

[0036] The positive electrode external terminal 221P is arranged to overlap with the radial center of the wound electrode body 10 when viewed from the axial direction Z. The positive electrode external terminal 221P is formed of, for example, aluminum, copper, or stainless steel, etc.

[0037] The positive electrode external terminal 221P is disposed on the first direction Z1 side of the wound electrode body 10. The positive electrode external terminal 221P includes a disk portion 221PA and a rivet portion 221PB.

[0038] The disk portion 221PA is exposed to the outside. When viewed from the negative electrode external terminal 221N, the disk portion 221PA is located at a position opposite to the wound electrode body 10.

[0039] The rivet portion 221PB is connected to the disk portion 221PA. The rivet portion 221PB extends from the center of the disk portion 221PA when viewed from the axial direction Z. The rivet portion 221PB is substantially located on the winding axis α of the wound electrode body 10. When viewed from the disk portion 221PA, the rivet portion 221PB extends toward the second direction Z2 side.

[0040] The negative electrode external terminal 221N has a plate-like outer shape. Specifically, the negative electrode external terminal 221N has a substantially circular plate-like outer shape. The negative electrode external terminal 221N is arranged to be orthogonal to the axial direction Z. A through-hole 221Nh is provided in the negative electrode external terminal 221N. Therefore, when viewed from the axial direction Z, the negative electrode external terminal 221N has an annular outer shape. The rivet portion 221PB of the positive electrode external terminal 221P is inserted through the through-hole 221Nh. Thus, the rivet portion 221PB extends into the interior of the unit case 20.

[0041] The negative electrode external terminal 221N is formed of aluminum or an aluminum alloy, copper, or stainless steel.

[0042] Moreover, the negative electrode external terminal 221N is fixed to the case main body 21. Details of the state in which the negative electrode external terminal 221N is fixed to the case main body will be described later.

[0043] The first current collector member 30 is connected to the positive electrode 11P. Specifically, the first current collector member 30 is arranged to project from the positive electrode current collecting foil 111P of the positive electrode 11P toward one side (the first direction Z1 side) in the axial direction Z. Therefore, the first current collector member 30 is disposed on the above-mentioned one side (the first direction Z1 side) in the axial direction Z of the wound electrode body 10.

[0044] The first current collector member 30 is connected to the positive electrode external terminal 221P. Specifically, the first current collector member 30 and the rivet portion 221PB of the positive electrode external terminal 221P are joined by welding.

[0045] The first current collector member 30 has an outer shape like a tab lead, but the shape of the first current collector member 30 is not particularly limited. The first current collector member 30 may also be a plate-like member extending in the plane direction orthogonal to the axial direction Z. The first current collector member 30 has conductivity. The material constituting the first current collector member 30 is not particularly limited. The first current collector member 30 may also contain the metal contained in the positive electrode current collecting foil 111P or the positive electrode external terminal 221P.

[0046] The second current collector member 40 is connected to the negative electrode 11N. Specifically, the second current collector member 40 is arranged to project from the negative electrode current collecting foil 111N of the negative electrode 11N toward one side (the first direction Z1 side) in the axial direction Z. Therefore, the second current collector member 40 is disposed on the above-mentioned one side (the first direction Z1 side) in the axial direction Z of the wound electrode body 10.

[0047] Moreover, the second current collector member 40 is disposed between the housing main body 21 and the negative external terminal 221N. The second current collector member 40 is joined to the negative external terminal 221N by being fixed to the housing main body 21 together with the negative external terminal 221N. Specifically, the second current collector member 40 and the negative external terminal 221N are fixed to the tightening portion 212 together. In other words, the second current collector member 40 and the negative external terminal 221N are fixed to the housing main body 21 by tightening.

[0048] More specifically, the sealing layer 215 is disposed between the negative external terminal 221N and the second current collector member 40 and the tightening portion 212. The sealing layer 215 is provided to cover the outer peripheral edge of the negative external terminal 221N and the end portion of the second current collector member 40 on the side opposite to the negative electrode 11N side.

[0049] The second current collector member 40 has an ear-lead-like outer shape, but the shape of the second current collector member 40 is not particularly limited. The second current collector member 40 may also be a plate-like member extending in a plane direction orthogonal to the axial direction Z. The second current collector member 40 has conductivity. The material constituting the second current collector member 40 is not particularly limited. The second current collector member 40 may also contain the metal contained in the negative current collector foil 111N or the negative external terminal 221N.

[0050] The power storage unit 1 of the present embodiment may further include a first internal insulating member 50, a second internal insulating member 60, and a third internal insulating member 70.

[0051] The first internal insulating member 50 is disposed on the inner surface of the negative external terminal 221N. The first internal insulating member 50 is disposed between the negative external terminal 221N and the first current collector member 30. The first internal insulating member 50 is provided to insulate the negative external terminal 221N and the first current collector member 30.

[0052] The second internal insulating member 60 is housed in the unit housing 20. The second internal insulating member 60 is disposed on the first direction Z1 side of the wound electrode body 10. In the axial direction Z, the second internal insulating member 60 is disposed between the wound electrode body 10 and the tightening portion 212. A first through hole 61 and a second through hole 62 are formed in the second internal insulating member 60. The first current collector member 30 is inserted through the first through hole 61. The second current collector member 40 is inserted through the second through hole 62.

[0053] The third internal insulating member 70 is housed in the unit housing 20. The third internal insulating member 70 is disposed on the second direction Z2 side of the wound electrode body 10. The third internal insulating member 70 is disposed between the bottom portion 214 and the wound electrode body 10. The third internal insulating member 70 is provided to insulate the bottom portion 214 and the wound electrode body 10.

[0054] As described above, the power storage unit 1 according to Embodiment 1 of the present disclosure includes a wound electrode body 10, a unit case 20, a first current collector member 30, and a second current collector member 40. The wound electrode body 10 includes a positive electrode 11P (first electrode) and a negative electrode 11N (second electrode). The unit case 20 houses the wound electrode body 10. The first current collector member 30 is connected to the positive electrode 11P. The second current collector member 40 is connected to the negative electrode 11N. The unit case 20 includes a case main body 21 and a lid 22. The case main body 21 has an opening 211 that opens on one side in the axial direction Z of the wound electrode body 10 when viewed from the wound electrode body 10. The lid 22 closes the opening 211 of the case main body 21. The lid 22 includes a positive electrode external terminal 221P (first external terminal) and a negative electrode external terminal 221N (second external terminal). The positive electrode external terminal 221P is arranged to overlap with the radial center of the wound electrode body 10 when viewed from the axial direction Z. The negative electrode external terminal 221N is fixed to the case main body 21. The first current collector member 30 is arranged on the above-mentioned one side in the axial direction Z of the wound electrode body 10. The first current collector member 30 is connected to the positive electrode external terminal 221P. The second current collector member 40 is arranged on the above-mentioned one side in the axial direction Z of the wound electrode body 10. The second current collector member 40 is arranged between the case main body 21 and the negative electrode external terminal 221N. The second current collector member 40 is joined to the negative electrode external terminal 221N by being fixed to the case main body 21 together with the negative electrode external terminal 221N.

[0055] According to the above configuration, at a position farther from the first current collector member 30 connected to the positive electrode external terminal 221P (first external terminal), the negative electrode external terminal 221N (second external terminal) and the second current collector member 40 are joined to each other. Therefore, a short circuit between the first current collector member 30 and the second current collector member 40 can be suppressed. Therefore, according to the above configuration, a power storage unit 1 that suppresses a short circuit inside the unit case 20 can be provided.

[0056] In addition, in the present embodiment, the case main body 21 further includes a constriction portion 212 formed by constricting an end portion on the above-mentioned one side of the wound electrode body 10. The second current collector member 40 and the negative electrode external terminal 221N (second external terminal) are fixed to the constriction portion 212 together.

[0057] When the case main body 21 is connected to the lid 22 by welding, foreign matter may enter the unit case 20. However, according to the above configuration, compared with the case where the case main body 21 is connected to the lid 22 by welding, the entry of foreign matter into the unit case 20 is suppressed. Therefore, according to the above configuration, a power storage unit 1 that further suppresses a short circuit inside the unit case 20 can be provided.

[0058] In addition, in the present embodiment, the housing main body 21 further includes an electrically insulating sealing layer 215 disposed between the negative electrode external terminal 221N (the second external terminal), the second current collecting member 40, and the tightening portion 212.

[0059] According to the above configuration, it is possible to prevent the negative electrode external terminal 221N (the second external terminal) from being short-circuited with the positive electrode 11P (the first electrode) or a member electrically connected to the positive electrode 11P via the housing main body 21.

[0060] Embodiment 2

[0061] Next, the power storage unit according to Embodiment 2 of the present disclosure will be described. In Embodiment 2 of the present disclosure, mainly the configuration of the second current collecting member is different from that of Embodiment 1 of the present disclosure. Therefore, the same configurations and effects as those in Embodiment 1 of the present disclosure will not be repeatedly described.

[0062] Figure 3 is a cross-sectional view showing the power storage unit of Embodiment 2. As Figure 3 shown, in Embodiment 2, the housing main body 21a does not include the tightening portion and the sealing layer shown in Embodiment 1. An opening 211 is formed at the end of the cylindrical wall portion 213a on the first direction Z1 side. In the present embodiment, the entire housing main body 21a has conductivity.

[0063] The negative electrode external terminal 221Na is directly joined to the housing main body 21a. The negative electrode external terminal 221Na is directly joined to the opening 211 of the housing main body 21a (the cylindrical wall portion 213a). The negative electrode external terminal 221Na is joined to the housing main body 21a by welding. The negative electrode external terminal 221Na is joined to the opening 211 of the housing main body 21a (the cylindrical wall portion 213a) by welding. A welding portion 217 is formed between the negative electrode external terminal 221Na and the housing main body 21a (the cylindrical wall portion 213a).

[0064] The second current collecting member 40a is provided to protrude from the negative electrode current collecting foil 111N of the negative electrode 11N toward the other side (the second direction Z2 side) in the axial direction Z. Therefore, the second current collecting member 40a is disposed on the other side (the second direction Z2 side) in the axial direction Z of the wound electrode body 10.

[0065] The second current collecting member 40a is directly connected to the housing main body 21a. The second current collecting member 40a may also be joined to the housing main body 21a by welding or the like. The second current collecting member 40a is connected to the bottom portion 214. The second current collecting member 40a may also be connected to the cylindrical wall portion 213a. The second current collecting member 40a may also be connected to both the bottom portion 214 and the cylindrical wall portion 213a.

[0066] In this embodiment, the second through-hole as shown in Embodiment 1 may not be formed in the second internal insulating member 60a. On the other hand, a third through-hole 71 is formed in the third internal insulating member 70a. A second current collector member 40a is inserted through the third through-hole 71.

[0067] As described above, the power storage unit 1a of Embodiment 2 of the present disclosure includes a wound electrode body 10, a unit case 20, a first current collector member 30, and a second current collector member 40a. The wound electrode body 10 includes a positive electrode 11P (first electrode) and a negative electrode 11N (second electrode). The unit case 20 houses the wound electrode body 10. The first current collector member 30 is connected to the positive electrode 11P. The second current collector member 40a is connected to the negative electrode 11N. The unit case 20 includes a case main body 21a and a lid 22. The case main body 21a has conductivity and has an opening 211 that opens on one side in the axial direction Z of the wound electrode body 10 when viewed from the wound electrode body 10. The lid 22 closes the opening 211 of the case main body 21a. The lid 22 includes a positive external terminal 221P (first external terminal) and a negative external terminal 221Na (second external terminal). The positive external terminal 221P is arranged to overlap the radial center of the wound electrode body 10 when viewed from the axial direction Z. The negative external terminal 221Na is directly joined to the case main body 21a. The first current collector member 30 is arranged on the above-mentioned one side in the axial direction Z of the wound electrode body 10. The first current collector member 30 is connected to the positive external terminal 221P. The second current collector member 40a is arranged on the other side in the axial direction Z of the wound electrode body 10. The second current collector member 40a is directly connected to the case main body 21a.

[0068] According to the above configuration, at a position far from the first current collector member 30 connected to the positive external terminal 221P (first external terminal), the negative external terminal 221Na (second external terminal) and the second current collector member 40a are electrically connected to each other via the case main body 21a. Therefore, a short circuit between the first current collector member 30 and the second current collector member 40a can be suppressed. Therefore, according to the above configuration, a power storage unit 1a in which a short circuit inside the unit case 20 is suppressed can be provided.

[0069] In addition, in this embodiment, the negative external terminal 221Na (second external terminal) is joined to the case main body 21a by welding.

[0070] According to the above configuration, the distance between the wound electrode body 10 and the lid 22 can be shortened as compared with the case where the negative external terminal 221Na (second external terminal) is joined by tightening the case main body 21a. Therefore, the energy density of the power storage unit 1a can be improved.

[0071] In the description of the above embodiments, the configurations that can be combined may be combined with each other.

[0072] The embodiments disclosed herein should be considered illustrative in all aspects and not restrictive. The scope of the present utility model is not represented by the description of the above embodiments, but by the claims, and is intended to include all modifications within the meaning and scope equivalent to the claims.

Claims

1. A power storage unit, characterized in that: have: A wound electrode body comprising a first electrode and a second electrode; a unit housing for housing the wound electrode body; a first current collecting member connected to the first electrode; as well as a second current collecting member connected to the second electrode; The unit housing includes a housing body and a cover, The case body has an opening portion that opens on one side in the axial direction of the wound electrode body when viewed from the wound electrode body. The cover blocks the opening of the housing body. The cover includes a first external terminal and a second external terminal, The first external terminal is arranged so as to overlap with the radial center of the wound electrode body when viewed in the axial direction. The second external terminal is fixed to the housing body, The first current collecting member is arranged on the one side in the axial direction of the wound electrode body and is connected to the first external terminal. The second current collecting member is disposed on the one side in the axial direction of the wound electrode body and between the case body and the second external terminal. The second current collecting member is joined to the second external terminal by being fixed to the case body together with the second external terminal.

2. The power storage unit according to claim 1, wherein The outer shell body further includes a tightening portion formed by tightening the end portion of the wound electrode body on one side in the axial direction. The second current collecting member is fixed to the clamping portion together with the second external terminal.

3. The power storage unit according to claim 2, wherein: The case body further includes a sealing layer disposed between the second external terminal and the second current collecting member and the clamping portion and having electrical insulation properties.

4. A power storage unit, characterized in that: have: A wound electrode body comprising a first electrode and a second electrode; a unit housing for housing the wound electrode body; a first current collecting member connected to the first electrode; as well as a second current collecting member connected to the second electrode; The unit housing includes a housing body and a cover, The case body has electrical conductivity and has an opening portion that opens on one side in the axial direction of the wound electrode body when viewed from the wound electrode body. The cover blocks the opening of the housing body. The cover includes a first external terminal and a second external terminal, The first external terminal is arranged so as to overlap with the radial center of the wound electrode body when viewed in the axial direction. The second external terminal is directly connected to the housing body. The first current collecting member is arranged on the one side in the axial direction of the wound electrode body and is connected to the first external terminal. The second current collecting member is disposed on the other side of the wound electrode body in the axial direction and is directly connected to the case body.

5. The power storage unit according to claim 4, wherein: The second external terminal is joined to the housing body by welding.

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