Electricity storage unit

Abstract

The present disclosure provides a power storage unit capable of suppressing a short circuit inside a unit case. A power storage cell according to the present disclosure is provided with a wound electrode body and a cell case. The wound electrode body includes a positive electrode and a negative electrode. The unit case accommodates the wound electrode body. The unit case includes a case body and a cover. The housing main body is open in one direction. The cover closes the housing main body. The cap includes a positive electrode external terminal, a negative electrode external terminal, and an insulating member. The positive electrode external terminal is directly joined to the case main body. The negative electrode external terminal is electrically connected to the negative electrode. The insulating member electrically insulates the positive electrode external terminal from the negative electrode external terminal. The positive electrode external terminal is electrically connected to the positive electrode via the housing main body.

Description

Technical Field

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

[0002] Japanese Patent No. 3322321 discloses a conventional non-aqueous electrolyte secondary battery as a power storage unit. In this non-aqueous electrolyte secondary battery, the negative and positive electrodes are wound with a porous separator between them and inserted into a cylindrical container. Leads extend from the positive and negative electrodes. The cylindrical container is made of stainless steel. The container lid is welded to the container opening at its periphery. A portion of the container lid is provided with a positive and negative electrode terminal. Utility Model Content

[0003] When both positive and negative terminals are provided on the lid, as in the storage cell disclosed in Japanese Patent No. 3322321, the positive and negative leads within the container become relatively close to each other, potentially causing the leads to contact and short-circuit.

[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 battery cell disclosed herein includes a wound electrode assembly and a cell case. The wound electrode assembly includes a positive electrode and a negative electrode. The cell case houses the wound electrode assembly. The cell case includes a case body and a cover. The case body is open in one direction. The cover closes the case body.

[0006] The cover contains a positive external terminal, a negative external terminal, and an insulating member. The positive external terminal is directly bonded to the housing body. The negative external terminal is electrically connected to the negative electrode. The insulating member electrically insulates the positive and negative external terminals.

[0007] The positive electrode external terminal is electrically connected to the positive electrode via the case body.

[0008] According to the above structure, it is no longer necessary to provide a positive tab lead or the like between the wound electrode body and the cover.

[0009] Therefore, the positive electrode current collecting member does not come into contact with negatively charged components between the wound electrode body and the cover. This further prevents short circuits within the cell casing.

[0010] According to the present disclosure, it is possible to suppress a short circuit inside the unit case. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Hereinafter, features, advantages, and technical and industrial significance of exemplary embodiments of the present invention will be described with reference to the accompanying drawings, wherein like symbols denote like elements.

[0012] Figure 1This is a cross-sectional view showing the power storage cell according to the first embodiment.

[0013] Figure 2 It is a perspective view showing a partially exploded wound electrode body.

[0014] Figure 3 This is an exploded perspective view partially showing the power storage unit according to the first embodiment.

[0015] Figure 4 This is another exploded perspective view partially showing the power storage unit according to the first embodiment.

[0016] Figure 5 This is a cross-sectional view showing a power storage cell according to the second embodiment.

[0017] Figure 6 It is an exploded perspective view partially showing the power storage unit according to the second embodiment. DETAILED DESCRIPTION

[0018] Hereinafter, the power storage unit according to each embodiment of the present disclosure will be described with reference to the accompanying drawings. The same or corresponding parts in the drawings are denoted by the same reference numerals, and their description will not be repeated.

[0019] Implementation Method 1

[0020] Figure 1 : is a cross-sectional view showing the power storage unit of the first embodiment. Figure 1 As shown, the electricity storage cell 1 according to the first embodiment of the present disclosure includes a wound electrode body 10 , a cell case 20 , a negative electrode current collecting member 30 , and an inner gasket 40 .

[0021] First, the wound electrode body 10 will be described. Figure 2 This is a partially exploded perspective view of the wound electrode body. Figure 1 and Figure 2 As shown, the wound electrode body 10 is wound into a cylindrical shape. Figure 2 , a state in which the wound electrode body 10 is slightly unwound is shown.

[0022] The wound electrode body 10 includes a positive electrode 11P, a negative electrode 11N, and a separator 12. The positive electrode 11P and the negative electrode 11N have sheet-like shapes. 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 the separator 12 interposed therebetween.

[0023] The separator 12 is provided between the positive electrode 11P and the negative electrode 11N. The separator 12 allows ions (eg, lithium ions) to pass between the positive electrode 11P (positive electrode active material) and the negative electrode 11N (negative electrode active material), and separates the positive electrode 11P from the negative electrode 11N.

[0024] 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 aluminum or an aluminum alloy.

[0025] The positive electrode mixture layer 112P is stacked on the positive electrode collector foil 111P. Specifically, the positive electrode mixture layer 112P is coated on both radial surfaces of the positive electrode collector foil 111P (positive electrode coating portion 111PA described later). The positive electrode mixture layer 112P is in close contact with the separator 12. In this embodiment, the radial outer surface of the wound electrode body 10 is composed of the positive electrode 11P. Specifically, the radial outer surface of the wound electrode body 10 is composed of the positive electrode collector foil 111P. That is, the positive electrode mixture layer 112P is not stacked on the outer surface of the positive electrode collector foil 111P located at the radial outermost side of the wound electrode body 10.

[0026] Positive electrode mixture layer 112P is formed by applying positive electrode slurry to the surface of positive electrode current collector foil 111P and drying it. Positive electrode slurry is prepared by kneading the materials for positive electrode mixture layer 112P (such as the positive electrode active material and the binder) with a solvent. The thickness of positive electrode mixture layer 112P is, for example, 0.1 μm to 1000 μm.

[0027] The positive electrode current collector foil 111P includes a positive electrode coated portion 111PA and a positive electrode uncoated portion 111PB. The positive electrode coated portion 111PA is the portion of the positive electrode current collector foil 111P coated with the positive electrode mixture layer 112P. In other words, the positive electrode coated portion 111PA is the portion covered by the positive electrode mixture layer 112P and not exposed.

[0028] The positive electrode uncoated portion 111PB is the exposed portion of the positive electrode current collector foil 111P that is not covered by the positive electrode mixture layer 112P. The positive electrode uncoated portion 111PB is located further to the side in the second direction Z2 than the positive electrode coated portion 111PA. The second direction Z2 is the opposite direction to the first direction Z1 along the axial direction Z. Specifically, the positive electrode uncoated portion 111PB protrudes from the positive electrode coated portion 111PA toward the side in the second direction Z2. The positive electrode uncoated portion 111PB is bent radially inward about the winding axis α.

[0029] The positive electrode uncoated portion 111PB includes a plurality of extending portions 111PC. The plurality of extending portions 111PC are arranged along the winding direction of the wound electrode body 10.

[0030] 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 has a sheet-like outer shape and is formed of, for example, copper.

[0031] The negative electrode mixture layer 112N is stacked on the negative electrode collector foil 111N. Specifically, the negative electrode mixture layer 112N is coated on both radial surfaces of the negative electrode collector foil 111N (negative electrode coating portion 111NA described later). 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 on the surface of the negative electrode collector foil 111N and drying it. The negative electrode slurry is a slurry prepared by kneading the materials of the negative electrode mixture layer 112N (negative electrode active material and binder, etc.) and a solvent. The thickness of the negative electrode mixture layer 112N is, for example, not less than 0.1 μm and not more than 1000 μm.

[0032] The negative electrode current collector foil 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 foil 111N coated with the negative electrode mixture layer 112N. In other words, the negative electrode coated portion 111NA is the portion covered by the negative electrode mixture layer 112N and not exposed.

[0033] The negative electrode uncoated portion 111NB is the portion not coated with the negative electrode mixture layer 112N. In other words, the negative electrode uncoated portion 111NB is the portion of the negative electrode current collector foil 111N that is not covered by the negative electrode mixture layer 112N and is exposed. The negative electrode uncoated portion 111NB is located further to the first direction Z1 side along the axial direction than the negative electrode coated portion 111NA. The negative electrode uncoated portion 111NB protrudes from the negative electrode coated portion 111NA to one side in the axial direction Z of the wound electrode body 10. Specifically, the negative electrode uncoated portion 111NB protrudes from the negative electrode coated portion 111NA to the first direction Z1 side along the axial direction Z. The negative electrode uncoated portion 111NB is bent radially inward about the winding axis α.

[0034] The negative electrode uncoated portion 111NB includes a plurality of extending portions 111NC. The plurality of extending portions 111NC are arranged along the winding direction of the wound electrode body 10.

[0035] Next, the unit case 20 will be described. Figure 3 This is an exploded perspective view partially showing the power storage unit according to the first embodiment. Figure 4 FIG. 1 is another exploded perspective view partially showing the power storage unit of the first embodiment. Figure 1 、 Figure 3 and Figure 4 As shown, the cell case 20 houses the wound electrode body 10 . The cell case 20 includes a case body 21 and a lid 22 .

[0036] The housing body 21 is open in one direction. Specifically, the housing body 21 is open in the first direction Z1. The housing body 21 has a bottomed cylindrical outer shape. The housing body 21 is formed of aluminum or an aluminum alloy.

[0037] The case body 21 is directly bonded to the positive electrode current collector foil 111P. Specifically, the case body 21 is welded to the positive electrode uncoated portion 111PB (plural extension portions 111NC). The case body 21 is directly bonded to the positive electrode current collector foil 111P on the second direction Z2 side of the wound electrode body 10.

[0038] The shell body 21 includes a cylindrical wall portion 211 and a bottom portion 212. The cylindrical wall portion 211 is provided in a manner covering the outer peripheral side of the wound electrode body 10. The cylindrical wall portion 211 covers the entire outer peripheral side of the wound electrode body 10. The cylindrical wall portion 211 has a cylindrical shape. The cylindrical wall portion 211 may also have a rectangular cylindrical shape. The inner peripheral surface of the cylindrical wall portion 211 is in close contact with the positive electrode 11P constituting the radially outer surface of the wound electrode body 10. Specifically, the inner peripheral surface of the cylindrical wall portion 211 is in contact with the positive electrode collector foil 111P. However, the inner peripheral surface of the cylindrical wall portion 211 may also be in contact with the positive electrode mixture layer 112P. The inner peripheral surface of the cylindrical wall portion 211 may also be in contact with the separator 12.

[0039] From the perspective of the wound electrode body 10, the bottom 212 is arranged on one side in the axial direction Z. Specifically, from the perspective of the wound electrode body 10, the bottom 212 is arranged on the second direction Z2 side along the axial direction Z. The bottom 212 is connected to the end of the cylindrical wall portion 211 on the second direction Z2 side. In the present embodiment, the bottom 212 is formed integrally with the cylindrical wall portion 211. The bottom 212 can also be formed as a component different from the cylindrical wall portion 211. In this case, the outer peripheral edge of the bottom 212 can also be joined to the cylindrical wall portion 211 by laser welding or the like. The bottom 212 is electrically connected to the cylindrical wall portion 211.

[0040] Bottom 212 is joined to positive electrode uncoated portion 111PB by welding from the outside of cell case 20. This positively charges bottom 212. The cylindrical wall portion 211 connected to bottom 212 is also positively charged. Furthermore, bottom 212 can also be used as a positive electrode terminal in power storage cell 1.

[0041] The bottom portion 212 includes an annular ridge portion 212A, multiple radial ridge portions 212B, and multiple welded portions 212C. The annular ridge portion 212A extends annularly with the winding axis α of the wound electrode body 10 as the center, as viewed in the axial direction Z. The annular ridge portion 212A protrudes toward the first direction Z1. That is, the annular ridge portion 212A protrudes toward the wound electrode body 10. The annular ridge portion 212A contacts the positive electrode uncoated portion 111PB of the positive electrode 11P.

[0042] The plurality of radial ridges 212B are arranged so as to be separated from each other in the circumferential direction centered on the winding axis α of the wound electrode body 10 when viewed in the axial direction Z. The plurality of radial ridges 212B are arranged at equal intervals in the circumferential direction.

[0043] Each of the plurality of radial ridges 212B extends in a radial direction centered on the winding axis α of the wound electrode body 10. The radial ridges 212B are connected to the annular ridge 212A.

[0044] The radial ridge portion 212B protrudes toward the first direction Z1. That is, the radial ridge portion 212B protrudes toward the wound electrode body 10. The radial ridge portion 212B contacts the positive electrode uncoated portion 111PB of the positive electrode 11P.

[0045] The plurality of welded portions 212C are portions of the bottom portion 212 that are joined to the positive electrode uncoated portion 111PB by welding. The plurality of welded portions 212C are formed by laser welding or the like from the outside of the unit housing 20. The plurality of welded portions 212C are formed on the annular ridge portion 212A. In the annular ridge portion 212A, the plurality of welded portions 212C are formed so as to extend in the circumferential direction. The plurality of welded portions 212C are respectively formed on the plurality of radial ridge portions 212B. In the radial ridge portion 212B, the welded portions 212C are formed so as to extend in the radial direction. The thickness of the annular ridge portion 212A and the plurality of radial ridge portions 212B may also be thinner than that of other portions of the bottom portion 212. This facilitates the formation of the welded portions 212C.

[0046] A through hole 212h is formed in the bottom portion 212. The through hole 212h can also be used to inject an electrolyte (not shown) contained in the unit case 20. The through hole 212h is formed in the center of the bottom portion 212 when viewed in the axial direction Z.

[0047] The sealing plug 213 is inserted into the through hole 212h of the bottom 212. Thus, the sealing plug 213 is fixed to the bottom 212. The sealing plug 213 and the through hole 212h 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.

[0048] The cover 22 closes the case body 21. The cover 22 includes a positive electrode external terminal 221P, a negative electrode external terminal 221N, and an insulating member 222.

[0049] The positive external terminal 221P has a plate-like shape. Specifically, the positive external terminal 221P has a roughly circular plate-like shape. The positive external terminal 221P is positioned perpendicular to the axial direction Z. A through-hole 221Ph is provided in the positive external terminal 221P. Therefore, when viewed in the axial direction Z, the positive external terminal 221P has a ring-shaped shape. The positive external terminal 221P is formed from aluminum or an aluminum alloy.

[0050] The positive external terminal 221P is directly bonded to the case body 21 (cylindrical wall portion 211). Consequently, the positive external terminal 221P connected to the case body 21 (cylindrical wall portion 211) is also positively charged. Therefore, in this embodiment, the positive external terminal 221P is electrically connected to the positive electrode 11P via the case body 21. Alternatively, the positive external terminal 221P can be bonded to the cylindrical wall portion 211 by caulking the end of the cylindrical wall portion 211.

[0051] The positive external terminal 221P is joined to the end portion of the case body 21 (cylindrical wall portion 211 ) on the first direction Z1 side by laser welding or other welding methods.

[0052] The negative electrode external terminal 221N is electrically connected to the negative electrode 11N via a negative electrode current collecting member 30 described later. The negative electrode external terminal 221N is formed of, for example, aluminum, copper, or stainless steel.

[0053] The negative electrode external terminal 221N is arranged on the first direction Z1 side of the wound electrode body 10. The negative electrode external terminal 221N includes a disk portion 221NA and a rivet portion 221NB.

[0054] The disk portion 221NA is exposed to the outside and is located opposite to the wound electrode body 10 when viewed from the positive electrode external terminal 221P.

[0055] The rivet portion 221NB is connected to the disk portion 221NA. The rivet portion 221NB extends from the center of the disk portion 221NA when viewed in the axial direction Z. The rivet portion 221NB is approximately located on the winding axis α of the wound electrode body 10. The rivet portion 221NB extends toward the second direction Z2 when viewed from the disk portion 221NA. The rivet portion 221NB is inserted into the through-hole 221Ph. The rivet portion 221NB extends into the interior of the unit case 20.

[0056] The insulating member 222 electrically insulates the positive external terminal 221P from the negative external terminal 221N. The insulating member 222 is disposed between the positive external terminal 221P and the negative external terminal 221N. The insulating member 222 covers the surface of the disk portion 221NA on the side in the second direction Z2. The rivet portion 221NB penetrates the insulating member 222 in the axial direction Z. The insulating member 222 covers the radially inner surface of the through-hole 221Ph in the positive external terminal 221P.

[0057] Next, the negative electrode current collecting member 30 will be described. Figure 1 and Figure 4As shown, the negative electrode current collecting member 30 is disposed in the cell case 20. The negative electrode current collecting member 30 is disposed on the first direction Z1 side of the wound electrode body 10. In this embodiment, the negative electrode current collecting member 30 has a plate-like outer shape, but may also be a tab-shaped lead.

[0058] The negative electrode current collecting member 30 is provided to electrically connect the negative electrode 11N to the negative electrode external terminal 221N. The negative electrode current collecting member 30 is welded to the negative electrode uncoated portion 111NB of the negative electrode 11N. This negatively charges the negative electrode current collecting member 30. The negative electrode current collecting member 30 is welded to the end of the rivet portion 221NB of the negative electrode external terminal 221N on the second direction Z2 side. This negatively charges the negative electrode external terminal 221N.

[0059] The negative electrode current collecting member 30 has a substantially disk-shaped outer shape and includes a central portion 31 , an outer peripheral portion 32 , a plurality of spokes 33 , and a plurality of tabs 34 .

[0060] The central portion 31 is located at a position overlapping with the rivet portion 221NB of the negative external terminal 221N when viewed in the axial direction Z. The central portion 31 is joined to the rivet portion 221NB of the negative external terminal 221N by welding.

[0061] The outer peripheral edge portion 32 is provided on the outer peripheral edge of the negative electrode current collecting member 30. The outer peripheral edge portion 32 is located on the outer periphery of the central portion 31. The outer peripheral edge portion 32 extends in an annular shape centered on the central portion 31. The outer peripheral edge portion 32 may also contact the negative electrode uncoated portion 111NB of the negative electrode 11N. However, the outer peripheral edge portion 32 does not bond to the negative electrode uncoated portion 111NB.

[0062] The spokes 33 are spaced apart from each other. The spokes 33 are arranged at equal intervals in the circumferential direction around the central portion 31. The spokes 33 connect the central portion 31 and the outer peripheral portion 32. The spokes 33 have an outer shape with a substantially uniform width from the central portion 31 to the outer peripheral portion 32.

[0063] The plurality of pieces 34 are separated from each other. The plurality of pieces 34 are arranged at equal intervals in a direction centered on the central portion 31. The plurality of spokes 33 and the plurality of pieces 34 are arranged so that the spokes 33 and the pieces 34 are alternately arranged in a circumferential direction centered on the central portion 31.

[0064] The piece 34 extends from the outer peripheral edge portion 32 toward the central portion 31. The piece 34 is connected to the negative electrode 11N. Specifically, the piece 34 is joined to the negative electrode uncoated portion 111NB of the negative electrode 11N by welding. Figure 4 , a path PN on the negative electrode current collecting member 30 from the joining portion between the sheet portion 34 and the negative electrode uncoated portion 111NB to the joining portion between the central portion 31 and the rivet portion 221NB is schematically shown.

[0065] The piece 34 includes a fan-shaped portion 341 and a neck portion 342. The fan-shaped portion 341 is joined to the negative electrode uncoated portion 111NB of the negative electrode 11N by welding. The tip of the fan-shaped portion 341 faces the central portion 31. The fan-shaped portion 341 extends toward the outer peripheral edge portion 32 along two adjacent spokes 33 on either side in the circumferential direction. This increases the surface area of ​​the fan-shaped portion 341, facilitating welding to the negative electrode uncoated portion 111NB of the negative electrode 11N.

[0066] Neck 342 connects outer peripheral edge 32 and fan-shaped portion 341. Neck 342 may also contact negative electrode uncoated portion 111NB of negative electrode 11N. However, neck 342 does not engage with negative electrode uncoated portion 111NB of negative electrode 11N. The circumferential dimension of neck 342 is smaller than the circumferential dimension of the outer peripheral edge of fan-shaped portion 341. As a result, sheet 34 is easily flexed in neck 342.

[0067] Here, an example of a method for welding the central portion 31 and the rivet portion 221NB of this embodiment is described. First, before welding the central portion 31 and the rivet portion 221NB, the fan-shaped portion 341 of the sheet portion 34 is pre-welded to the negative electrode uncoated portion 111NB of the negative electrode 11N. Next, a welding device is inserted from the second direction Z2 side of the wound electrode body 10 along the winding axis α of the wound electrode body 10. The welding device presses the central portion 31 from the second direction Z2 side and welds the central portion 31 and the rivet portion 221NB to each other using the welding device. At this time, the connection portion between the spoke 33 and the central portion 31 and the connection portion between the spoke 33 and the outer peripheral edge portion 32 are greatly bent on the path PN. As a result, the central portion 31 can be easily displaced relative to the sheet portion 34 in the axial direction Z. Therefore, even if the welding device contacts the center portion 31, the connection between the tab portion 34 and the negative electrode uncoated portion 111NB can be prevented from being damaged due to displacement of the center portion 31. Furthermore, the connection between the negative electrode current collecting member 30 and the negative electrode external terminal 221N is facilitated.

[0068] The internal gasket 40 is housed in the cell case 20. It covers the surface of the positive electrode external terminal 221P on the side in the second direction Z2. The internal gasket 40 is formed of an insulating material. Therefore, the internal gasket 40 insulates the wound electrode assembly 10 from the positive electrode external terminal 221P. The rivet portion 221NB penetrates the internal gasket 40 in the axial direction Z.

[0069] Specifically, the internal gasket 40 is positioned between the negative current collecting member 30 and the positive external terminal 221P. This electrically insulates the negative current collecting member 30 and the positive external terminal 221P. Furthermore, the internal gasket 40 extends toward the outer periphery of the negative current collecting member 30. This also positions the internal gasket 40 between the negative current collecting member 30 and the cylindrical wall portion 211. Consequently, the negative current collecting member 30 and the cylindrical wall portion 211 are electrically insulated from each other.

[0070] As described above, the storage cell 1 of the first embodiment of the present disclosure includes a wound electrode body 10 and a cell case 20. The wound electrode body 10 includes a positive electrode 11P and a negative electrode 11N. The cell case 20 houses the wound electrode body 10. The cell case 20 includes a case body 21 and a cover 22. The case body 21 is open in one direction. The cover 22 closes the case body 21. The cover 22 includes a positive electrode external terminal 221P, a negative electrode external terminal 221N, and an insulating member 222. The positive electrode external terminal 221P is directly bonded to the case body 21. The negative electrode external terminal 221N is electrically connected to the negative electrode 11N. The insulating member 222 electrically insulates the positive electrode external terminal 221P from the negative electrode external terminal 221N. The positive electrode external terminal 221P is electrically connected to the positive electrode 11P via the case body 21.

[0071] This configuration eliminates the need for a positive electrode current collecting member, such as a tab lead, between the wound electrode body 10 and the lid 22. Consequently, the positive electrode current collecting member does not come into contact with negatively charged components between the wound electrode body 10 and the lid 22. Furthermore, short circuits within the cell case 20 can be suppressed.

[0072] In this embodiment, 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 aluminum or an aluminum alloy. The positive electrode mixture layer 112P is laminated on the positive electrode current collector foil 111P. The case body 21 is directly bonded to the positive electrode current collector foil 111P. The case body 21 is formed of aluminum or an aluminum alloy. The positive electrode external terminal 221P is formed of aluminum or an aluminum alloy.

[0073] According to the above configuration, the case body 21 is directly bonded to the positive electrode current collector foil 111P, thereby reducing the weight of the case body 21. The case body 21 is formed of aluminum or an aluminum alloy, further reducing the weight of the case body 21. The case body 21 and the positive electrode current collector foil 111P are both formed of aluminum or an aluminum alloy and are directly bonded to each other, thereby reducing contact resistance. Furthermore, the positive electrode external terminal 221P and the case body 21 are formed of aluminum or an aluminum alloy, further reducing contact resistance.

[0074] Implementation Method 2

[0075] Next, the power storage unit according to the second embodiment of the present disclosure will be described. The power storage unit according to the second embodiment of the present disclosure differs from the first embodiment of the present disclosure in that it further includes a positive electrode current collecting member. Therefore, the same structure and effects as those of the first embodiment of the present disclosure will not be described repeatedly.

[0076] Figure 5 This is a cross-sectional view showing a power storage cell according to the second embodiment. Figure 6 It is an exploded perspective view partially showing the power storage unit according to the second embodiment.

[0077] like Figure 5 and Figure 6 As shown, the electricity storage cell 1a further includes a positive electrode current collecting member 50. The positive electrode current collecting member 50 is disposed between the wound electrode body 10 and the case body 21 on the side opposite to the lid 22 when viewed from the wound electrode body 10. The positive electrode current collecting member 50 is formed of aluminum or an aluminum alloy. The positive electrode current collecting member 50 is directly bonded to the positive electrode current collecting foil 111P. The positive electrode current collecting member 50 is connected to the case body 21.

[0078] The above configuration can suppress internal short circuits between the wound electrode body 10 and the lid 22, and can also increase the degree of freedom in the connection method between the case body 21 and the positive electrode 11P via the positive electrode current collecting member 50. Furthermore, the positive electrode current collecting member 50, the positive electrode current collecting foil 111P, and the case body 21 are all formed of aluminum or an aluminum alloy, and these are connected to each other, thereby suppressing increases in contact resistance.

[0079] In this embodiment, the positive electrode current collecting member 50 has a plate-like shape, but it may also be a tab-shaped lead. The positive electrode current collecting member 50 is welded to the positive electrode uncoated portion 111PB of the positive electrode 11P. This causes the positive electrode current collecting member 50 to be positively charged. The positive electrode current collecting member 50 may or may not be welded to the case body 21 (bottom 212). However, the positive electrode current collecting member 50 is in close contact with the bottom 212. This also causes the case body 21 to be positively charged.

[0080] Like the negative electrode current collecting member 30, the positive electrode current collecting member 50 includes a central portion 51, an outer peripheral portion 52, a plurality of spokes 53, and a plurality of tabs 54. However, in the positive electrode current collecting member 50, each tab 54 extends from the central portion 51 toward the outer peripheral portion 52. The tabs 54 are connected to the positive electrode 11P. Specifically, the tabs 54 are joined to the positive electrode uncoated portion 111PB of the positive electrode 11P by welding.

[0081] The embodiments disclosed herein are illustrative in all respects and should not be construed as restrictive. The scope of the present disclosure is not represented by the description of the above embodiments, but by the scope of the patent claims, including all changes within the meaning and scope equivalent to the scope of the patent claims.

Claims

1. A power storage unit, characterized in that: have: A wound electrode body including a positive electrode and a negative electrode, and a unit case for housing the wound electrode body, The unit housing includes a housing body opened in one direction and a cover closing the housing body. The cover includes: a positive electrode external terminal directly joined to the case body, a negative electrode external terminal electrically connected to the negative electrode, and an insulating member electrically insulating the positive electrode external terminal from the negative electrode external terminal. The positive electrode external terminal is electrically connected to the positive electrode via the case body.

2. The power storage unit according to claim 1, wherein The positive electrode comprises a positive electrode current collector foil and a positive electrode mixture layer. The positive electrode current collector foil is formed of aluminum or an aluminum alloy. The positive electrode mixture layer is laminated on the positive electrode current collector foil. The shell body is directly bonded to the positive electrode collector foil. The housing body is formed of aluminum or aluminum alloy. The positive electrode external terminal is formed of aluminum or an aluminum alloy.

3. The power storage unit according to claim 1, wherein The invention further comprises a positive electrode current collecting member disposed between the wound electrode body and the case body on the opposite side of the cover when viewed from the wound electrode body. The positive electrode comprises a positive electrode current collector foil and a positive electrode mixture layer. The positive electrode current collector foil is formed of aluminum or an aluminum alloy. The positive electrode mixture layer is laminated on the positive electrode current collector foil. The positive electrode current collecting member is formed of aluminum or an aluminum alloy, The positive electrode current collecting member is directly bonded to the positive electrode current collecting foil. The positive electrode current collecting member is connected to the shell body, The housing body is formed of aluminum or aluminum alloy. The positive electrode external terminal is formed of aluminum or an aluminum alloy.

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