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] Japanese Patent No. 3322321 discloses a non-aqueous electrolyte secondary battery as a power storage unit. In the non-aqueous electrolyte secondary battery, the negative electrode and the positive electrode are wound with a porous separator, 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. The container cover is welded to the opening of the container at the periphery. A positive terminal and a negative terminal are provided on a part of the container cover. Summary of the invention

[0003] In the case of a storage cell disclosed in Japanese Patent No. 3322321, where both the positive and negative terminals are provided on the cover, the positive and negative leads in the container are close to each other, which may cause the leads to contact each other and short-circuit, for example.

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

[0005] The first aspect of the present disclosure provides a storage unit comprising a wound electrode body, a unit housing, a first current collecting member, and a second current collecting member. The wound electrode body comprises a first electrode and a second electrode. The unit housing accommodates the wound electrode body. The first current collecting member is connected to the first electrode. The second current collecting member is connected to the second electrode. The unit housing comprises a housing body and a cover. The housing body comprises an opening portion which opens on one side in the axial direction of the wound electrode body when viewed from the wound electrode body. The cover seals the opening portion of the housing body. The cover comprises a first external terminal and a second external terminal. The first external terminal is configured to overlap with the radial center of the wound electrode body when viewed from the above-mentioned axial direction. The second external terminal is fixed to the housing body. The first current collecting member is configured on the above-mentioned one side in the axial direction of the wound electrode body. The first current collecting member is connected to the first external terminal. The second current collecting member is configured on the above-mentioned one side in the axial direction of the wound electrode body. The second current collecting member is configured between the housing 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.

[0006] According to the above configuration, the second external terminal and the second current collecting member are joined to each other at a position far from the first current collecting member connected to the first external terminal. Therefore, a short circuit between the first current collecting member and the second current collecting member can be suppressed. Therefore, according to the above configuration, a storage cell can be provided in which a short circuit inside the cell casing is suppressed.

[0007] The storage cell of the second aspect of the present disclosure comprises a wound electrode body, a cell housing, a first current collecting member, and a second current collecting member. The wound electrode body comprises a first electrode and a second electrode. The cell housing accommodates the wound electrode body. The first current collecting member is connected to the first electrode. The second current collecting member is connected to the second electrode. The cell housing comprises a housing body and a cover. The housing body is conductive 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 seals the opening portion of the housing body. The cover comprises a first external terminal and a second external terminal. The first external terminal is configured to overlap with 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 body. The first current collecting member is configured on the above-mentioned one side in the above-mentioned axial direction of the wound electrode body. The first current collecting member is connected to the first external terminal. The second current collecting member is configured on the other side in the above-mentioned axial direction of the wound electrode body. The second current collecting member is directly connected to the housing body.

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

[0009] According to the present disclosure, it is possible to suppress a short circuit inside the unit casing. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Features, advantages, and technical and industrial significance of exemplary embodiments of the present invention will be described below with reference to the accompanying drawings, in which like reference numerals represent like elements.

[0011] Figure 1 is a perspective view showing the power storage unit according to the first embodiment;

[0012] Figure 2 Observe along the arrow direction of line II-II Figure 1 A cross-sectional view of a power storage unit;

[0013] Figure 3 This is a cross-sectional view showing a power storage unit according to the second embodiment. DETAILED DESCRIPTION

[0014] Hereinafter, the power storage unit according to 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 their description will not be repeated.

[0015] Implementation Method 1

[0016] Figure 1 This is a perspective view showing the power storage unit according to the first embodiment. Figure 2Observe along the arrow direction of line II-II Figure 1 A cross-sectional view of a power storage unit.

[0017] like Figure 1 and Figure 2 As shown, the electricity storage cell 1 of the first embodiment is a cylindrical battery. The electricity storage cell 1 includes a wound electrode body 10 , a cell case 20 , a first current collecting member 30 , and a second current collecting member 40 .

[0018] First, the wound electrode body 10 will be described. Figure 2 As 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 so as to surround the periphery of a winding axis α.

[0019] In the first embodiment, the positive electrode 11P is exemplified as the first electrode in the present disclosure. In the first embodiment, the negative electrode 11N is exemplified as the second electrode in the present disclosure. However, the first electrode may be a negative electrode. The second electrode may be a 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 an electrode plate group in which the positive electrode 11P and the negative electrode 11N are wound with a 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 (for example, lithium ions) to and from the positive electrode 11P (positive electrode active material) and the negative electrode 11N (negative electrode active material) to separate the positive electrode 11P from 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 made of, for example, aluminum.

[0023] The positive electrode mixture layer 112P is applied to both radial surfaces of the positive electrode 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 applying a positive electrode slurry to the surface of the positive electrode collector foil 111P and drying it. The positive electrode slurry is a slurry prepared by kneading the material (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, not less than 0.1 μm and not more than 1000 μm.

[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 made of, for example, copper.

[0025] The negative electrode mixture layer 112N is applied to both radial surfaces of the negative electrode 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 applying a negative electrode slurry to the surface of the negative electrode collector foil 111N and drying it. The negative electrode slurry is a slurry prepared by kneading the material 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 housing 20 will be described. Figure 1 as well as Figure 2 As shown, the unit case 20 accommodates the wound electrode body 10 . The unit case 20 includes a case main body 21 and a cover 22 .

[0027] The case 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 body 21. The case body 21 has a bottomed cylindrical outer shape.

[0028] The case body 21 further includes a clamped portion 212 formed by clamping (caulking) an end portion on one side (on the first direction Z1 side) of the wound electrode body 10 . The clamped portion 212 extends in an annular shape along the opening 211 .

[0029] The housing 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 in a manner covering the outer circumference of the wound electrode body 10. The cylindrical wall portion 213 covers the entire outer circumference 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 formed integrally with the tightening portion 212.

[0031] When viewed from the wound electrode body 10, the bottom 214 is arranged on the second direction Z2 side along the axial direction Z. The bottom 214 is connected to the end of the cylindrical wall portion 213 on the second direction Z2 side. In the present embodiment, the bottom 214 is formed integrally with the cylindrical wall portion 213. The bottom 214 may also be formed as a separate member from the cylindrical wall portion 213. At this time, the outer peripheral edge of the bottom 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) contained in the unit housing 20. A sealing plug 216 is inserted through the through hole 214h of 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 housing 20 when the pressure inside the unit housing 20 becomes too high.

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

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

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

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

[0037] The positive electrode external terminal 221P is arranged 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 and is located opposite to the wound electrode body 10 when viewed from the negative electrode external terminal 221N.

[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 in 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.

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

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

[0042] Furthermore, the negative electrode external terminal 221N is fixed to the case body 21. Details of how the negative electrode external terminal 221N is fixed to the case body will be described later.

[0043] The first current collecting member 30 is connected to the positive electrode 11P. Specifically, the first current collecting member 30 is provided so as to protrude from the positive electrode current collecting foil 111P of the positive electrode 11P to one side (the first direction Z1 side) in the axial direction Z. Therefore, the first current collecting member 30 is arranged 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 collecting member 30 is connected to the positive electrode external terminal 221P. Specifically, the first current collecting member 30 and the rivet portion 221PB of the positive electrode external terminal 221P are joined by welding.

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

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

[0047] Furthermore, the second current collecting member 40 is disposed between the case body 21 and the negative external terminal 221N. The second current collecting member 40 is joined to the negative external terminal 221N by being fixed to the case body 21 together with the negative external terminal 221N. Specifically, the second current collecting member 40 is fixed to the clamping portion 212 together with the negative external terminal 221N. In other words, the second current collecting member 40 is fixed to the case body 21 together with the negative external terminal 221N by clamping.

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

[0049] The second current collecting member 40 has a tab lead-shaped outer shape, but the shape of the second current collecting member 40 is not particularly limited. The second current collecting member 40 may also be a plate-shaped member extending in a plane direction orthogonal to the axial direction Z. The second current collecting member 40 has conductivity. The material constituting the second current collecting member 40 is not particularly limited. The second current collecting member 40 may also contain a metal contained in the negative electrode current collecting foil 111N or the negative electrode 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 provided on the inner surface of the negative external terminal 221N. The first internal insulating member 50 is provided between the negative external terminal 221N and the first current collecting member 30. The first internal insulating member 50 is provided to insulate the negative external terminal 221N from the first current collecting member 30.

[0052] The second internal insulating member 60 is accommodated in the unit housing 20. The second internal insulating member 60 is provided on the first direction Z1 side of the wound electrode body 10. In the axial direction Z, the second internal insulating member 60 is arranged 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 collector member 30 is inserted through the first through hole 61. The second collector member 40 is inserted through the second through hole 62.

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

[0054] As described above, the storage cell 1 of the first embodiment of the present disclosure includes a wound electrode body 10, a cell case 20, a first current collecting member 30, and a second current collecting member 40. The wound electrode body 10 includes a positive electrode 11P (first electrode) and a negative electrode 11N (second electrode). The cell case 20 accommodates the wound electrode body 10. The first current collecting member 30 is connected to the positive electrode 11P. The second current collecting member 40 is connected to the negative electrode 11N. The cell case 20 includes a case body 21 and a cover 22. The case 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 cover 22 blocks the opening 211 of the case body 21. The cover 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 configured 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 shell body 21. The first collector member 30 is configured on the above-mentioned one side in the axial direction Z of the wound electrode body 10. The first collector member 30 is connected to the positive electrode external terminal 221P. The second collector member 40 is configured on the above-mentioned one side in the axial direction Z of the wound electrode body 10. The second collector member 40 is configured between the shell body 21 and the negative electrode external terminal 221N. The second collector member 40 is joined to the negative electrode external terminal 221N by being fixed to the shell body 21 together with the negative electrode external terminal 221N.

[0055] According to the above configuration, the negative electrode external terminal 221N (second external terminal) and the second current collecting member 40 are joined to each other at a position far from the first current collecting member 30 connected to the positive electrode external terminal 221P (first external terminal). Therefore, it is possible to suppress a short circuit between the first current collecting member 30 and the second current collecting member 40. Therefore, according to the above configuration, it is possible to provide a storage cell 1 in which a short circuit inside the cell case 20 is suppressed.

[0056] In the present embodiment, the case body 21 further includes a clamping portion 212 formed by clamping the one end of the wound electrode body 10. The second current collecting member 40 is fixed to the clamping portion 212 together with the negative electrode external terminal 221N (second external terminal).

[0057] When the case body 21 is connected to the cover 22 by welding, foreign matter may enter the unit case 20. However, according to the above configuration, compared with the case body 21 being connected to the cover 22 by welding, foreign matter is prevented from entering the unit case 20. Therefore, according to the above configuration, it is possible to provide the power storage unit 1 in which short circuits inside the unit case 20 are further prevented.

[0058] In the present embodiment, the case body 21 further includes a sealing layer 215 having electrical insulation properties disposed between the negative electrode external terminal 221N (second external terminal) and the second current collecting member 40 and the clamping portion 212 .

[0059] According to the above configuration, it is possible to suppress short circuit between the negative electrode external terminal 221N (second external terminal) and the positive electrode 11P (first electrode) or a member electrically connected to the positive electrode 11P via the case body 21 .

[0060] Implementation Method 2

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

[0062] Figure 3 2 is a cross-sectional view showing a power storage unit according to Embodiment 2. Figure 3 As shown, in Embodiment 2, the housing body 21a does not include the tightening portion and the sealing layer shown in Embodiment 1. The end of the cylindrical wall portion 213a on the first direction Z1 side forms the opening 211. In this embodiment, the housing body 21a as a whole has conductivity.

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

[0064] The second current collecting member 40 a is provided to protrude from the negative electrode current collecting foil 111N of the negative electrode 11N to the other side (the second direction Z2 side) in the axial direction Z. Therefore, the second current collecting member 40 a 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 body 21a. The second current collecting member 40a may be joined to the housing body 21a by welding or the like. The second current collecting member 40a is connected to the bottom 214. The second current collecting member 40a may be connected to the cylindrical wall portion 213a. The second current collecting member 40a may be connected to both the bottom 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, the third through hole 71 is formed in the third internal insulating member 70a. The second current collecting member 40a is inserted through the third through hole 71.

[0067] As described above, the power storage cell 1a of the second embodiment of the present disclosure includes a wound electrode body 10, a cell case 20, a first current collecting member 30, and a second current collecting member 40a. The wound electrode body 10 includes a positive electrode 11P (first electrode) and a negative electrode 11N (second electrode). The cell case 20 accommodates the wound electrode body 10. The first current collecting member 30 is connected to the positive electrode 11P. The second current collecting member 40a is connected to the negative electrode 11N. The cell case 20 includes a case body 21a and a cover 22. The case 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 cover 22 blocks the opening 211 of the case body 21a. The cover 22 includes a positive electrode external terminal 221P (first external terminal) and a negative electrode external terminal 221Na (second external terminal). The positive electrode external terminal 221P is configured to overlap with the radial center of the wound electrode body 10 when viewed in the axial direction Z. The negative electrode external terminal 221Na is directly joined to the outer shell body 21a. The first collector member 30 is configured on the above-mentioned one side in the axial direction Z of the wound electrode body 10. The first collector member 30 is connected to the positive electrode external terminal 221P. The second collector member 40a is configured on the other side in the axial direction Z of the wound electrode body 10. The second collector member 40a is directly connected to the outer shell body 21a.

[0068] According to the above configuration, the negative electrode external terminal 221Na (second external terminal) and the second current collecting member 40a are electrically connected to each other via the housing body 21a at a position far from the first current collecting member 30 connected to the positive electrode external terminal 221P (first external terminal). Therefore, it is possible to suppress a short circuit between the first current collecting member 30 and the second current collecting member 40a. Therefore, according to the above configuration, it is possible to provide a storage cell 1a in which a short circuit inside the cell housing 20 is suppressed.

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

[0070] According to the above configuration, the distance between the wound electrode body 10 and the lid 22 can be shortened compared to the case body 21a is tightened to join the negative electrode external terminal 221Na (second external terminal). Therefore, the energy density of the power storage cell 1a can be increased.

[0071] In the description of each embodiment described above, it is also possible to combine the configurations that can be combined with each other.

[0072] The embodiments disclosed this time should be considered in all respects as illustrative and non-restrictive. The scope of the present invention is indicated not 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 comprising: A wound electrode body including 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; and 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 closes the opening of the housing body. The cover 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 in the axial direction. The second external terminal is fixed to the housing body, The first current collecting member is disposed 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, and 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, The case body further includes a tightening portion formed by tightening the end portion of the wound electrode body on the 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, 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 comprising: A wound electrode body including 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; and a second current collecting member connected to the second electrode, The unit housing includes a housing body and a cover, The case 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 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 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 disposed 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, The second external terminal is joined to the case body by welding.

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