Electricity storage unit

Abstract

The present disclosure provides a power storage unit having further improved reliability. In a power storage cell according to the present disclosure, a first wound electrode body includes a first positive electrode and a first negative electrode. The second wound electrode body includes a second positive electrode and a second negative electrode. The second positive electrode is not in contact with the first positive electrode. The second negative electrode is not in contact with the first negative electrode. The second wound electrode body is formed by winding around the first wound electrode body on the outside of the first wound electrode body. The positive electrode current collector is electrically connected to both the first positive electrode and the second positive electrode. The negative electrode current collector is electrically connected to both the first negative electrode and the second negative electrode.

Description

Technical Field

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

[0002] Japanese Patent Application Laid-Open No. 11-273743 discloses a cylindrical non-aqueous electrolyte secondary battery in which a spirally wound electrode assembly and a non-aqueous electrolyte are housed in a cylindrical battery can. Utility Model Content

[0003] For example, in a storage cell such as a secondary battery disclosed in Japanese Patent Application Laid-Open No. 11-273743, pressure is sometimes applied to the outer circumference of the casing. In this case, the casing deforms, further pressing against the electrode assembly inside. This compresses the electrode assembly, affecting the original function of the storage cell. There is room for further improvement in the reliability of storage cells.

[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 with further improved reliability.

[0005] The storage unit according to the present disclosure comprises a first wound electrode body, a second wound electrode body, a shell, a positive electrode current collecting member, and a negative electrode current collecting member. The first wound electrode body includes a first positive electrode and a first negative electrode. The second wound electrode body includes a second positive electrode and a second negative electrode. The second positive electrode is not in contact with the first positive electrode. The second negative electrode is not in contact with the first negative electrode. The second wound electrode body is formed by winding the first wound electrode body around the outer periphery of the first wound electrode body. The shell accommodates the first wound electrode body and the second wound electrode body. The positive electrode current collecting member is accommodated in the shell. The positive electrode current collecting member is arranged on one side of the first wound electrode body and the second wound electrode body in the axial direction of the first wound electrode body. The positive electrode current collecting member is electrically connected to both the first positive electrode and the second positive electrode. The negative electrode current collecting member is accommodated in the shell. The negative electrode current collecting member is arranged on the other side of the first wound electrode body and the second wound electrode body in the above-mentioned axial direction. The negative electrode current collecting member is electrically connected to both the first negative electrode and the second negative electrode.

[0006] With this structure, even if the second wound electrode assembly is damaged by pressure applied to the case from the outer circumference, the first wound electrode assembly can function normally together with the positive and negative current collecting members. This further improves the reliability of the power storage unit.

[0007] According to the present disclosure, it is possible to provide a power storage unit having further improved reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] 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 represent like elements.

[0009] Figure 1 This is a cross-sectional view showing a power storage cell according to one embodiment.

[0010] Figure 2 It is a perspective view showing a first wound electrode body, a second wound electrode body, and a heat insulating member in a partially exploded manner.

[0011] Figure 3 This is an exploded perspective view showing a power storage unit according to one embodiment.

[0012] Figure 4 This is another exploded perspective view showing the power storage unit according to one embodiment. DETAILED DESCRIPTION

[0013] Hereinafter, an electric storage unit according to an embodiment of the present disclosure will be described with reference to the accompanying drawings. Identical or corresponding parts in the drawings are denoted by the same reference numerals, and their description will not be repeated.

[0014] Figure 1 : is a cross-sectional view showing an electric storage unit according to one embodiment. Figure 1 As shown, the electricity storage cell 1 according to one embodiment of the present disclosure is a cylindrical battery and includes a first wound electrode body 10 , a second wound electrode body 20 , a case 30 , a positive electrode current collecting member 40 , a negative electrode current collecting member 50 , and a heat insulating member 60 .

[0015] First, the first wound electrode body 10 will be described. Figure 2 : is a partially exploded perspective view showing the first wound electrode body, the second wound electrode body and the heat insulating member. Figure 1 and Figure 2 As shown in FIG, the first wound electrode body 10 is wound into a cylindrical shape. Figure 2 , a state in which the first wound electrode body 10 is slightly unwound is shown.

[0016] The first wound electrode body 10 includes a first positive electrode 11P, a first negative electrode 11N, and a first separator 12. The first wound electrode body 10 is wound so that the first positive electrode 11P, the first negative electrode 11N, and the first separator 12 surround a winding axis α.

[0017] The first positive electrode 11P and the first negative electrode 11N have sheet-like outer shapes. The first wound electrode body 10 is composed of an electrode plate group in which the first positive electrode 11P and the first negative electrode 11N are wound with a first separator 12 interposed therebetween.

[0018] The first separator 12 is provided between the first positive electrode 11P and the first negative electrode 11N. The first separator 12 allows ions (e.g., lithium ions) to flow between the first positive electrode 11P (positive electrode active material) and the first negative electrode 11N (negative electrode active material) and separates the first positive electrode 11P from the first negative electrode 11N.

[0019] The first positive electrode 11P includes a first positive electrode current collector foil 111P and a first positive electrode mixture layer 112P. The first positive electrode current collector foil 111P is made of, for example, aluminum.

[0020] The first positive electrode mixture layer 112P is applied to both radial surfaces of the first positive electrode current collector foil 111P (the first positive electrode coating portion 111PA described below). The first positive electrode mixture layer 112P is in close contact with the first separator 12. The first positive electrode mixture layer 112P is formed by applying a positive electrode slurry to the surface of the first positive electrode current collector foil 111P and drying it. The positive electrode slurry is a slurry prepared by kneading the materials of the first positive electrode mixture layer 112P (positive electrode active material and binder, etc.) with a solvent. The thickness of the first positive electrode mixture layer 112P is, for example, not less than 0.1 μm and not more than 1000 μm.

[0021] The first positive electrode current collector foil 111P includes a first positive electrode coated portion 111PA and a first positive electrode uncoated portion 111PB. The first positive electrode coated portion 111PA is the portion of the first positive electrode current collector foil 111P coated with the first positive electrode mixture layer 112P. In other words, the first positive electrode coated portion 111PA is the portion covered by the first positive electrode mixture layer 112P and not exposed.

[0022] The first positive electrode uncoated portion 111PB is the exposed portion of the first positive electrode current collector foil 111P that is not covered by the first positive electrode mixture layer 112P. The first positive electrode uncoated portion 111PB is located closer to the first direction Z1 than the first positive electrode coated portion 111PA along the axial direction Z. Specifically, the first positive electrode uncoated portion 111PB protrudes from the first positive electrode coated portion 111PA in the first direction Z1. The first positive electrode uncoated portion 111PB is bent radially inward.

[0023] The first 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 first wound electrode body 10.

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

[0025] The first negative electrode mixture layer 112N is applied to both radial surfaces of the first negative electrode current collector foil 111N (the first negative electrode coating portion 111NA described later). The first negative electrode mixture layer 112N is in close contact with the first separator 12. The first negative electrode mixture layer 112N is formed by applying a negative electrode slurry to the surface of the first negative electrode current collector foil 111N and drying it. The negative electrode slurry is a slurry prepared by kneading the materials of the first negative electrode mixture layer 112N (such as a negative electrode active material and a binder) with a solvent. The thickness of the first negative electrode mixture layer 112N is, for example, not less than 0.1 μm and not more than 1000 μm.

[0026] The first negative electrode current collector foil 111N includes a first negative electrode coating portion 111NA and a first negative electrode uncoated portion 111NB. The first negative electrode coating portion 111NA is the portion of the first negative electrode current collector foil 111N coated with the first negative electrode mixture layer 112N. In other words, the first negative electrode coating portion 111NA is the portion covered by the first negative electrode mixture layer 112N and not exposed.

[0027] The first negative electrode uncoated portion 111NB is the exposed portion of the first negative electrode current collector foil 111N that is not covered by the first negative electrode mixture layer 112N. The first negative electrode uncoated portion 111NB is located axially closer to the second direction Z2 than the first negative electrode coated portion 111NA. The second direction Z2 is opposite to the first direction Z1. The first negative electrode uncoated portion 111NB protrudes from the first negative electrode coated portion 111NA in the second direction Z2 along the axial direction Z. The first negative electrode uncoated portion 111NB is bent radially inward.

[0028] The first 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 first wound electrode body 10.

[0029] Next, the second wound electrode body 20 will be described. Figure 1 and Figure 2 As shown in FIG. 1 , the second wound electrode body 20 is formed by winding the first wound electrode body 10 around the outer periphery of the first wound electrode body 10. The second wound electrode body 20 is wound into a cylindrical shape. Figure 2 , a state in which the second wound electrode body 20 is slightly unwound is shown.

[0030] The second wound electrode body 20 includes a second positive electrode 21P, a second negative electrode 21N, and a second separator 22. In the second wound electrode body 20, the second positive electrode 21P, the second negative electrode 21N, and the second separator 22 are wound around the winding axis α, similarly to the first wound electrode body 10.

[0031] The second positive electrode 21P is not in contact with the first positive electrode 11P. The second positive electrode 21P is formed from a member that is discontinuous with the first positive electrode 11P. The second negative electrode 21N is not in contact with the first negative electrode 11N. The second negative electrode 21N is formed from a member that is discontinuous with the first negative electrode 11N. In this embodiment, the second separator 22 is formed from a member that is discontinuous with the first separator 12. However, the second separator 22 may also be formed from an integral member together with the first separator 12.

[0032] In addition to the above-described structure, the second wound electrode body 20 can have the same structure as the first wound electrode body 10. In addition to the above-described structure, the second positive electrode 21P, the second negative electrode 21N, and the second separator 22 in the second wound electrode body 20 have the same structures as the first positive electrode 11P, the first negative electrode 11N, and the first separator 12 in the first wound electrode body 10, respectively.

[0033] The second positive electrode 21P includes a second positive electrode collector foil 211P and a second positive electrode mixture layer 212P. The second positive electrode collector foil 211P and the second positive electrode mixture layer 212P in the second positive electrode 21P have the same structures as the first positive electrode collector foil 111P and the first positive electrode mixture layer 112P in the first positive electrode 11P, respectively. The second positive electrode collector foil 211P includes a second positive electrode coating portion 211PA and a second positive electrode uncoated portion 211PB. The second positive electrode coating portion 211PA and the second positive electrode uncoated portion 211PB in the second positive electrode collector foil 211P have the same structures as the first positive electrode coating portion 111PA and the first positive electrode uncoated portion 111PB in the first positive electrode collector foil 111P, respectively. The second positive electrode uncoated portion 211PB includes a plurality of extension portions 211PC, similarly to the first positive electrode uncoated portion 111PB.

[0034] The second negative electrode 21N includes a second negative electrode collector foil 211N and a second negative electrode mixture layer 212N. The second negative electrode collector foil 211N and the second negative electrode mixture layer 212N in the second negative electrode 21N have the same structures as the first negative electrode collector foil 111N and the first negative electrode mixture layer 112N in the first negative electrode 11N, respectively. The second negative electrode collector foil 211N includes a second negative electrode coating portion 211NA and a second negative electrode uncoated portion 211NB. The second negative electrode coating portion 211NA and the second negative electrode uncoated portion 211NB in ​​the second negative electrode collector foil 211N have the same structures as the first negative electrode coating portion 111NA and the first negative electrode uncoated portion 111NB in ​​the first negative electrode collector foil 111N, respectively. The second negative electrode uncoated portion 211NB includes a plurality of extending portions 211NC, similarly to the plurality of extending portions 111NC in the first negative electrode uncoated portion 111NB.

[0035] Next, the housing 30 will be described. Figure 3This is an exploded perspective view showing a power storage unit according to one embodiment. Figure 4 FIG. 1 is another exploded perspective view showing an electric storage unit according to an embodiment of the present invention. Figure 1 、 Figure 3 and Figure 4 As shown, the case 30 accommodates the first wound electrode body 10 and the second wound electrode body 20 .

[0036] The case 30 includes a positive electrode terminal 31P, a negative electrode terminal 31N, a cylindrical wall portion 32 , a sealing plate 33 , a sealing plug 34 , an outer gasket 35 , an inner gasket 36 , and an annular gasket 37 .

[0037] The positive terminal 31P is exposed to the outside of the shell 30. The positive terminal 31P is arranged on the first direction Z1 side of the first wound electrode body 10. The positive terminal 31P includes a disk portion 311 and a rivet portion 312. The disk portion 311 is exposed to the outside. The rivet portion 312 is connected to the disk portion 311. The rivet portion 312 extends from the center of the disk portion 311 when viewed in the axial direction Z. The rivet portion 312 is approximately located on the winding axis α of the first wound electrode body 10. The rivet portion 312 extends to the second direction Z2 side. The positive terminal 31P is formed of, for example, aluminum.

[0038] The negative terminal 31N is arranged to be perpendicular to the axial direction Z. A through hole 31Nh is provided in the negative terminal 31N. Therefore, when viewed from the axial direction Z, the negative terminal 31N has an annular shape. The negative terminal 31N is located between the disk portion 311 and the first wound electrode body 10 and the second wound electrode body 20 in the axial direction Z. The rivet portion 312 is inserted into the through hole 31Nh. The rivet portion 312 extends to the interior of the shell 30. The material constituting the negative terminal 31N is not particularly limited and is formed of aluminum, copper, stainless steel, or the like.

[0039] The cylindrical wall portion 32 is provided on the outer circumference of the second wound electrode body 20. The cylindrical wall portion 32 covers the entire outer circumference of the second wound electrode body 20. The cylindrical wall portion 32 has a cylindrical shape. The end of the cylindrical wall portion 32 on the first direction Z1 side is connected to the negative electrode terminal 31N. The cylindrical wall portion 32 and the negative electrode terminal 31N are integrally formed. The material constituting the cylindrical wall portion 32 is not particularly limited and may be formed from aluminum, copper, stainless steel, or the like.

[0040] A caulking portion 32d is formed at the end portion on the second direction Z2 side of the cylindrical wall portion 32. The caulking portion 32d is formed in an annular shape along the circumferential direction of the second wound electrode body 20. Figure 4 , the cylindrical wall portion 32 is shown in a state before the caulked portion 32d is formed.

[0041] The sealing plate 33 is connected to the end portion of the cylindrical wall portion 32 on the second direction Z2 side. The sealing plate 33 seals the opening of the cylindrical wall portion 32 on the second direction Z2 side. The caulking portion 32d caulks the outer peripheral edge of the sealing plate 33. Furthermore, the sealing plate 33 may be connected to the cylindrical wall portion 32 by welding such as laser welding. The material constituting the sealing plate 33 is not particularly limited and may be formed from aluminum, copper, stainless steel, or the like.

[0042] A through hole 33h is formed in the sealing plate 33. The through hole 33h can also be used to inject the electrolyte (not shown) contained in the case 30. The through hole 33h is formed in the center of the sealing plate 33 when viewed in the axial direction Z.

[0043] The sealing plug 34 is inserted into the through hole 33h of the sealing plate 33. Thus, the sealing plug 34 is fixed to the sealing plate 33. The sealing plug 34 and the through hole 33h can function as a pressure relief valve for releasing the pressure inside the housing 30 when the pressure inside the housing 30 becomes too high.

[0044] The external gasket 35 is disposed between the positive electrode terminal 31P and the negative electrode terminal 31N. The external gasket 35 is formed of an insulating material. Therefore, the external gasket 35 insulates the positive electrode terminal 31P from the negative electrode terminal 31N. The external gasket 35 covers the surface of the disc portion 311 on the side in the second direction Z2. The rivet portion 312 penetrates the external gasket 35 in the axial direction Z. The external gasket 35 covers the radially inner surface of the through hole 31Nh of the negative electrode terminal 31N.

[0045] The internal gasket 36 covers the surface of the negative electrode terminal 31N on the side in the second direction Z2. The internal gasket 36 is formed of an insulating material. Therefore, the internal gasket 36 insulates the first and second wound electrode bodies 10, 20 from the negative electrode terminal 31N. The rivet portion 312 also penetrates the internal gasket 36 in the axial direction Z. Therefore, the rivet portion 312 is exposed inside the case 30.

[0046] The annular gasket 37 has a circular ring shape. It covers the outer periphery of the sealing plate 33. It is positioned between the outer periphery of the sealing plate 33 and the caulked portion 32d of the cylindrical wall portion 32. The annular gasket 37 can be formed of either an insulating material or a conductive material. Furthermore, the housing 30 does not necessarily need to include the annular gasket 37.

[0047] In this embodiment, the sealing plate 33 is insulated from the cylindrical wall portion 32 by the annular gasket 37, but the sealing plate 33 may be electrically connected to the cylindrical wall portion 32. In this case, the sealing plate 33 may also be a negative electrode terminal.

[0048] In addition, in the present embodiment, the portion of the shell 30 facing the first direction Z1 side is composed of the positive terminal 31P, the negative terminal 31N and the external gasket 35. However, as a part of the above-mentioned portion, the shell 30 may also have a top plate portion. The top plate portion may be located, for example, on the inner peripheral side of the negative terminal 31N. The top plate portion may also be arranged in parallel with the positive terminal 31P in the axial direction Z. The top plate portion may also be insulated from the negative terminal 31N. In addition, as described above, in the case where the sealing plate 33 serves as the negative terminal, a top plate portion electrically insulated from the sealing plate 33 and the cylindrical wall portion 32 may also be arranged instead of the negative terminal 31N.

[0049] Next, the positive electrode current collecting member 40 will be described. Figure 1 and Figure 3 As shown, the positive electrode current collecting member 40 is housed in the case 30. The positive electrode current collecting member 40 is arranged on the first direction Z1 side of the first wound electrode body 10 and the second wound electrode body 20 in the axial direction Z of the first wound electrode body 10.

[0050] An internal gasket 36 is disposed between the positive current collecting member 40 and the negative electrode terminal 31N. This electrically insulates the positive current collecting member 40 and the negative electrode terminal 31N from each other. Furthermore, the internal gasket 36 extends toward the outer periphery of the positive current collecting member 40. Thus, the internal gasket 36 is also disposed between the positive current collecting member 40 and the cylindrical wall portion 32. Consequently, the positive current collecting member 40 and the cylindrical wall portion 32 are electrically insulated from each other.

[0051] The positive electrode current collecting member 40 has a plate-like outer shape. The positive electrode current collecting member 40 has a generally circular plate-like outer shape. The positive electrode current collecting member 40 includes a plurality of first positive electrode connecting portions 41, a plurality of second positive electrode connecting portions 42, a terminal connecting portion 43, a plurality of first fuse portions 44, a plurality of second fuse portions 45, an outer peripheral portion 46, and a plurality of positive electrode spoke portions 47.

[0052] The plurality of first positive electrode connectors 41 are each connected to the first positive electrode 11P. Specifically, the plurality of first positive electrode connectors 41 are each welded to the first positive electrode uncoated portion 111PB of the first positive electrode 11P. The plurality of first positive electrode connectors 41 are isolated from one another. The plurality of first positive electrode connectors 41 are arranged at equal intervals in the circumferential direction centered around the terminal connection portion 43.

[0053] The plurality of second positive electrode connecting portions 42 are each connected to the second positive electrode 21P. Specifically, the plurality of second positive electrode connecting portions 42 are each welded to the second positive electrode uncoated portion 211PB of the second positive electrode 21P. The plurality of second positive electrode connecting portions 42 are isolated from one another. The plurality of second positive electrode connecting portions 42 are arranged at equal intervals in a circumferential direction centered on the terminal connecting portion 43. The plurality of first positive electrode connecting portions 41 and the plurality of second positive electrode connecting portions 42 are alternately arranged in the circumferential direction.

[0054] The terminal connection portion 43 is connected to the positive electrode terminal 31P. Specifically, the terminal connection portion 43 is joined to the rivet portion 312 of the positive electrode terminal 31P by welding. Thus, in the present embodiment, the positive electrode terminal 31P is electrically connected to the positive electrode current collecting member 40. The terminal connection portion 43 is located at a position overlapping with the rivet portion 312 of the positive electrode terminal 31P when viewed from the axial direction Z. The terminal connection portion 43 is electrically connected to the first positive electrode connection portion 41 and the second positive electrode connection portion 42. However, in the present embodiment, the terminal connection portion 43 is configured in a manner isolated from the first positive electrode connection portion 41 and the second positive electrode connection portion 42.

[0055] The plurality of first fuses 44 are connected to the plurality of first positive electrode connectors 41, respectively. Each first fuse 44 is located opposite the terminal connector 43, as viewed from the corresponding first positive electrode connector 41. The circumferential dimension of the first fuse 44 is smaller than the circumferential dimension of the outer peripheral edge of the first positive electrode connector 41. The thickness of the first fuse 44 is preferably thinner than that of the first positive electrode connector 41.

[0056] The plurality of second fuses 45 are connected to the plurality of second positive electrode connectors 42, respectively. Each second fuse 45 is located opposite the terminal connector 43, as viewed from the corresponding second positive electrode connector 42. The circumferential dimension of the second fuse 45 is smaller than the circumferential dimension of the outer peripheral edge of the second positive electrode connector 42. The thickness of the second fuse 45 is preferably thinner than that of the second positive electrode connector 42.

[0057] The outer peripheral edge portion 46 is provided on the outer peripheral edge of the positive electrode current collecting member 40. The outer peripheral edge portion 46 is provided further outwardly than the plurality of first positive electrode connecting portions 41 and the plurality of second positive electrode connecting portions 42. The outer peripheral edge portion 46 is isolated from the plurality of first positive electrode connecting portions 41 and the plurality of second positive electrode connecting portions 42. The outer peripheral edge portion 46 is connected to the plurality of first fuse portions 44 and the plurality of second fuse portions 45. The outer peripheral edge portion 46 extends in an annular shape centered on the terminal connecting portion 43.

[0058] The plurality of positive electrode spokes 47 are isolated from one another. Each of the plurality of positive electrode spokes 47 connects the terminal connection portion 43 and the outer peripheral edge portion 46. Each of the plurality of positive electrode spokes 47 extends radially centered on the terminal connection portion 43. Each of the plurality of positive electrode spokes 47 is disposed between the first positive electrode connection portion 41 and the second positive electrode connection portion 42, which are adjacent to each other in the circumferential direction.

[0059] Therefore, the conductive path PP1 from the first positive electrode connecting portion 41 to the terminal connecting portion 43 in the positive electrode current collecting member 40 passes through the first fuse portion 44, the outer peripheral edge portion 46, and the positive electrode spoke portion 47 (see Figure 3The first fuse portion 44 is disposed in the conductive path PP1 extending from the first positive electrode connecting portion 41 to the terminal connecting portion 43 in the positive electrode current collecting member 40 .

[0060] In addition, the conductive path PP2 from the second positive electrode connecting portion 42 to the terminal connecting portion 43 in the positive electrode current collecting member 40 passes through the second fuse portion 45, the outer peripheral edge portion 46 and the positive electrode spoke portion 47 (see Figure 3 The second fuse portion 45 is disposed in the conductive path PP2 extending from the second positive electrode connecting portion 42 to the terminal connecting portion 43 in the positive electrode current collecting member 40 .

[0061] Furthermore, the first fuse 44 is provided so as not to be located on the conductive path PP2 from the second positive electrode connecting portion 42 to the terminal connecting portion 43 in the positive electrode current collecting member 40. The second fuse 45 is provided so as not to be located on the conductive path PP1 from the first positive electrode connecting portion 41 to the terminal connecting portion 43 in the positive electrode current collecting member 40.

[0062] In this embodiment, the positive electrode current collecting member 40 has the above-described structure, thereby being electrically connected to both the first positive electrode 11P and the second positive electrode 21P. This positively charges the positive electrode current collecting member 40. Furthermore, the positive electrode current collecting member 40 is electrically connected to the positive electrode terminal 31P. This positively charges the positive electrode terminal 31P.

[0063] Furthermore, the positive electrode current collecting member 40 is not limited to the plate-shaped member described above. The positive electrode current collecting member 40 may also be composed of multiple tab leads. One tab lead may electrically connect the first positive electrode 11P to the positive electrode terminal 31P, while another tab leads electrically connect the second positive electrode 21P to the positive electrode terminal 31P. Furthermore, one tab lead may be provided with the first fuse 44, and the other tab lead may be provided with the second fuse 45.

[0064] Next, the negative electrode current collecting member 50 will be described. Figure 1 and Figure 4 As shown, the negative electrode current collecting member 50 is housed in the case 30. The negative electrode current collecting member 50 is disposed on the second direction Z2 side of the first wound electrode body 10 and the second wound electrode body 20 in the axial direction Z. The negative electrode current collecting member 50 is electrically connected to both the first negative electrode 11N and the second negative electrode 21N. The structure of the negative electrode current collecting member 50 is not particularly limited.

[0065] The negative electrode current collecting member 50 in this embodiment is joined to the cylindrical wall portion 32 by being caulked together with the outer peripheral edge of the sealing plate 33 and the annular gasket 37 at the caulked portion 32 d.

[0066] The negative electrode current collecting member 50 has a plate-like outer shape. The negative electrode current collecting member 50 has a substantially disk-like outer shape. The negative electrode current collecting member 50 includes a plurality of first negative electrode connecting portions 51 , a plurality of second negative electrode connecting portions 52 , a case connecting portion 53 , a central portion 54 , and a plurality of negative electrode spoke portions 55 .

[0067] Each of the plurality of first negative electrode connecting portions 51 is connected to the first negative electrode 11N. Specifically, each of the plurality of first negative electrode connecting portions 51 is welded to the first negative electrode uncoated portion 111NB of the first negative electrode 11N. The plurality of first negative electrode connecting portions 51 are isolated from one another. The plurality of first negative electrode connecting portions 51 are arranged at equal intervals in a direction centered on the central portion 54.

[0068] Each of the plurality of second negative electrode connecting portions 52 is connected to the second negative electrode 21N. Specifically, each of the plurality of second negative electrode connecting portions 52 is welded to the second negative electrode uncoated portion 211NB of the second negative electrode 21N. The plurality of second negative electrode connecting portions 52 are isolated from one another. The plurality of second negative electrode connecting portions 52 are arranged at equal intervals in a direction centered on the central portion 54. The plurality of first negative electrode connecting portions 51 and the plurality of second negative electrode connecting portions 52 are arranged alternately in the circumferential direction.

[0069] The shell connection portion 53 is connected to the cylindrical wall portion 32. Specifically, the shell connection portion 53 is joined to the cylindrical wall portion 32 by being caulked together with the outer edge of the sealing plate 33 and the annular gasket at the caulking portion 32d. Thus, in the present embodiment, the negative terminal 31N is electrically connected to the negative electrode current collecting member 50 via the cylindrical wall portion 32. The shell connection portion 53 is provided on the outer peripheral edge of the negative electrode current collecting member 50. The shell connection portion 53 is provided on the outer peripheral side of the plurality of first negative electrode connection portions 51 and the plurality of second negative electrode connection portions 52. The shell connection portion 53 is isolated from the plurality of first negative electrode connection portions 51 and the plurality of second negative electrode connection portions 52. The shell connection portion 53 extends in a circular ring shape with the central portion 54 as the center.

[0070] The central portion 54 is located at a position overlapping the first wound electrode body 10 in the axial direction Z. The central portion 54 is provided on the inner circumference side of the plurality of first negative electrode connecting portions 51 and the plurality of second negative electrode connecting portions 52. The central portion 54 is connected to the plurality of first negative electrode connecting portions 51 and the plurality of second negative electrode connecting portions 52.

[0071] The negative electrode spokes 55 are isolated from one another. Each of the negative electrode spokes 55 connects the center portion 54 to the case connection portion 53. Each of the negative electrode spokes 55 extends radially about the center portion 54. Each of the negative electrode spokes 55 is disposed between the first negative electrode connecting portion 51 and the second negative electrode connecting portion 52, which are adjacent to each other in the circumferential direction.

[0072] Therefore, in the negative electrode current collecting member 50 , the conductive path PN1 from the first negative electrode connecting portion 51 to the case connecting portion 53 and the conductive path PN2 from the second negative electrode connecting portion 52 to the case connecting portion 53 both pass through the central portion 54 and the negative electrode spoke portion 55 .

[0073] Furthermore, the negative electrode current collecting member 50 is not limited to the plate-shaped member described above. The negative electrode current collecting member 50 may also be composed of multiple tab leads. Alternatively, one tab lead may electrically connect the first negative electrode 11N to the negative electrode terminal 31N, and another tab lead may electrically connect the second negative electrode 21N to the negative electrode terminal 31N. Furthermore, when the sealing plate 33 serves as the negative electrode terminal, or when the sealing plate 33 is electrically connected to the negative electrode terminal 31N, the first negative electrode 11N and the second negative electrode 21N may be directly joined to the sealing plate 33 by welding or the like.

[0074] Finally, the heat insulating member 60 will be described. Figures 1 to 4 As shown, the insulating member 60 has a cylindrical outer shape. The insulating member 60 is disposed between the first wound electrode body 10 and the second wound electrode body 20 in the radial direction of the first wound electrode body 10. The insulating member 60 is preferably formed of an electrically insulating member. For example, a resin composition such as a foamed resin can be used for the insulating member 60.

[0075] As described above, the electricity storage cell 1 according to one embodiment of the present disclosure includes: a first wound electrode body 10, a second wound electrode body 20, a case 30, a positive electrode current collecting member 40, and a negative electrode current collecting member 50. The first wound electrode body 10 includes a first positive electrode 11P and a first negative electrode 11N. The second wound electrode body 20 includes a second positive electrode 21P and a second negative electrode 21N. The second positive electrode 21P is not in contact with the first positive electrode 11P. The second negative electrode 21N is not in contact with the first negative electrode 11N. The second wound electrode body 20 is formed by winding the first wound electrode body 10 around the outer periphery of the first wound electrode body 10. The case 30 houses the first wound electrode body 10 and the second wound electrode body 20. The positive electrode current collecting member 40 is housed in the case 30. The positive electrode current collecting member 40 is disposed on one side of the first and second wound electrode bodies 10 and 20 in the axial direction Z of the first wound electrode body 10. The positive electrode current collecting member 40 is electrically connected to both the first positive electrode 11P and the second positive electrode 21P. The negative electrode current collecting member 50 is housed in the case 30. The negative electrode current collecting member 50 is disposed on the other side of the first and second wound electrode bodies 10 and 20 in the axial direction Z. The negative electrode current collecting member 50 is electrically connected to both the first and second negative electrodes 11N and 21N.

[0076] With the above configuration, even if pressure is applied to the case 30 from the outer circumference thereof, damaging the second wound electrode body 20, the first wound electrode body 10 can function normally together with the positive electrode current collecting member 40 and the negative electrode current collecting member 50. This further improves the reliability of the electricity storage unit 1.

[0077] In this embodiment, the housing 30 includes a positive electrode terminal 31P. The positive electrode terminal 31P is exposed outside the housing 30. The positive electrode terminal 31P is electrically connected to the positive electrode current collecting member 40. The positive electrode current collecting member 40 includes a first positive electrode connecting portion 41, a second positive electrode connecting portion 42, a terminal connecting portion 43, and a first fuse 44. The first positive electrode connecting portion 41 is connected to the first positive electrode 11P. The second positive electrode connecting portion 42 is connected to the second positive electrode 21P. The terminal connecting portion 43 is connected to the positive electrode terminal 31P. The first fuse 44 is arranged in the conductive path PP1 in the positive electrode current collecting member 40, extending from the first positive electrode connecting portion 41 to the terminal connecting portion 43.

[0078] Because the first wound electrode body 10 is located on the inner circumference of the second wound electrode body 20, heat dissipation is relatively difficult. However, with the above structure, if the first wound electrode body 10 overheats, the first fuse 44 is disconnected. Short circuits in the first wound electrode body 10 are suppressed. This further improves the safety of the storage cell 1.

[0079] In the present embodiment, the positive electrode current collecting member 40 includes a second fuse portion 45 . The second fuse portion 45 is disposed in the conductive path PP2 extending from the second positive electrode connecting portion 42 to the terminal connecting portion 43 in the positive electrode current collecting member 40 .

[0080] With the above configuration, when the second wound electrode assembly 20 is crushed and an excessive current flows through the second wound electrode assembly 20 , the second fuse 45 is disconnected, thereby suppressing a short circuit in the second wound electrode assembly 20 . This further improves the safety of the power storage unit 1 .

[0081] In this embodiment, the first fuse 44 is provided so as not to be located on the conductive path PP2 from the second positive electrode connecting portion 42 to the terminal connecting portion 43 in the positive electrode current collecting member 40. The second fuse 45 is provided so as not to be located on the conductive path PP1 from the first positive electrode connecting portion 41 to the terminal connecting portion 43 in the positive electrode current collecting member 40.

[0082] According to the above configuration, it is possible to individually suppress short circuits in the first wound electrode body 10 and short circuits in the second wound electrode body 20. This further improves both the reliability and safety of the electricity storage unit 1.

[0083] In the present embodiment, the electricity storage cell 1 further includes a cylindrical heat insulating member 60 . The heat insulating member 60 is disposed between the first wound electrode body 10 and the second wound electrode body 20 in the radial direction of the first wound electrode body 10 .

[0084] With this structure, when the first wound electrode body 10 overheats, the heat generated by the first wound electrode body 10 is prevented from being transferred to the second wound electrode body 20. The first fuse 44 is cut, thus preventing short circuits in the first wound electrode body 10. This allows the second wound electrode body 20 to function normally together with the positive electrode current collecting member 40 and the negative electrode current collecting member 50. This further improves the reliability of the power storage unit 1.

[0085] The embodiments disclosed herein are illustrative in all respects and should not be construed as restrictive. The scope of the present disclosure is not indicated by the description of the embodiments described above, but by the scope of the patent claims, and includes all modifications within the meaning and scope equivalent to the scope of the patent claims.

Claims

1. A power storage unit, characterized in that: The invention comprises a first wound electrode body, a second wound electrode body, a casing, a positive electrode current collecting member, and a negative electrode current collecting member. The first wound electrode body includes a first positive electrode and a first negative electrode. The second wound electrode body includes a second positive electrode that is not in contact with the first positive electrode and a second negative electrode that is not in contact with the first negative electrode, and the second wound electrode body is formed by winding the first wound electrode body around the outer periphery of the first wound electrode body. The case accommodates the first wound electrode body and the second wound electrode body. The positive electrode current collecting member is housed in the case and is arranged on one side of the first wound electrode body and the second wound electrode body in the axial direction of the first wound electrode body, and is electrically connected to both the first positive electrode and the second positive electrode. The negative electrode current collecting member is housed in the case, is disposed on the other side of the first wound electrode body and the second wound electrode body in the axial direction, and is electrically connected to both the first negative electrode and the second negative electrode.

2. The power storage unit according to claim 1, wherein The case includes a positive electrode terminal, the positive electrode terminal is exposed outside the case and is electrically connected to the positive electrode current collecting member. The positive electrode current collecting member includes a first positive electrode connecting portion, a second positive electrode connecting portion, a terminal connecting portion, and a first fuse portion. The first positive electrode connecting portion is connected to the first positive electrode, The second positive electrode connecting portion is connected to the second positive electrode, The terminal connection portion is connected to the positive terminal, The first fuse portion is disposed in a conductive path from the first positive electrode connecting portion to the terminal connecting portion in the positive electrode current collecting member.

3. The power storage unit according to claim 1, wherein The case includes a positive electrode terminal, the positive electrode terminal is exposed outside the case and is electrically connected to the positive electrode current collecting member. The positive electrode current collecting member includes a first positive electrode connecting portion, a second positive electrode connecting portion, a terminal connecting portion, and a second fuse portion. The first positive electrode connecting portion is connected to the first positive electrode, The second positive electrode connecting portion is connected to the second positive electrode, The terminal connection portion is connected to the positive terminal, The second fuse portion is disposed in a conductive path from the second positive electrode connecting portion to the terminal connecting portion in the positive electrode current collecting member.

4. The power storage unit according to claim 2, wherein: further comprising a second fuse portion, the second fuse portion being arranged in a conductive path from the second positive electrode connecting portion to the terminal connecting portion in the positive electrode current collecting member, The first fuse portion is provided so as not to be located on the conductive path from the second positive electrode connecting portion to the terminal connecting portion in the positive electrode current collecting member. The second fuse portion is provided so as not to be located on a conductive path from the first positive electrode connecting portion to the terminal connecting portion in the positive electrode current collecting member.

5. The power storage unit according to any one of claims 1 to 4, characterized in that A cylindrical heat insulating member is further provided. The cylindrical heat insulating member is arranged between the first wound electrode body and the second wound electrode body in the radial direction of the first wound electrode body.

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