Energy storage cell

Abstract

Further improve energy density. [Solution] In the energy storage cell 1 according to this disclosure, the first electrode 11N of the wound electrode body 10 includes a sheet-like current collector 111N and an electrode composite layer 112N formed on the current collector 111N. The current collector 111N includes a coated portion 111NA coated with the electrode composite layer 112N and an uncoated portion 111NB not coated with the electrode composite layer 112N. The uncoated portion 111NB protrudes from the coated portion 111NA to one side in the axial direction Z of the wound electrode body 10. The case 20 houses the wound electrode body 10. The case 20 includes a cylindrical wall portion 22 and a bottom portion 23. The cylindrical wall portion 22 is provided to cover the outer circumference of the wound electrode body 10. The bottom portion 23 is located on one side in the axial direction Z and is connected to one end of the cylindrical wall portion 22. The bottom portion 23 is joined to the unpainted portion 111NB by welding from the outside of the case 20.

Description

Technical Field

[0001] This disclosure relates to a storage battery cell.

Background Art

[0002] Patent Document 1 (Japanese Unexamined Patent Application Publication No. 10-162854) discloses a cylindrical battery having a spiral electrode group and a tabless current collection method. A single substantially disc-shaped current collector is welded to the conductive end edges of negative electrode plates protruding outward from the upper and lower end faces of the electrode group.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In a storage battery cell such as the cylindrical battery disclosed in Patent Document 1, there is room to further reduce the number of parts and further improve the energy density per unit volume of the cell.

[0005] This disclosure has been made in view of the above problems, and an object thereof is to provide a storage battery cell with further improved energy density.

Means for Solving the Problems

[0006] A storage cell according to this disclosure comprises a wound electrode body and a case. The wound electrode body includes a wound first electrode and a second electrode. The first electrode includes a sheet-like current collector and an electrode composite layer formed on the current collector. The current collector includes a coated portion coated with the electrode composite layer and an uncoated portion not coated with the electrode composite layer. The uncoated portion protrudes from the coated portion to one side in the axial direction of the wound electrode body. The case houses the wound electrode body. The case includes a cylindrical wall portion and a bottom portion. The cylindrical wall portion is provided to cover the outer circumference of the wound electrode body. The bottom portion is located on one side in the axial direction and is connected to one end of the cylindrical wall portion. The bottom portion is joined to the uncoated portion by welding from the outside of the case.

[0007] According to the above configuration, the bottom of the case has the function of collecting current for the first electrode. Therefore, a current collector plate, which is a different material from the case, is not required for the first electrode, and the number of components in the energy storage cell can be reduced. As a result, the space available in the case for housing the wound electrode body is increased, and a larger wound electrode body can be accommodated. Consequently, the energy density of the energy storage cell is further improved. [Effects of the Invention]

[0008] According to this disclosure, it is possible to provide energy storage cells with further improved energy density. [Brief explanation of the drawing]

[0009] [Figure 1] This is a cross-sectional view showing a power storage cell according to Embodiment 1. [Figure 2] This is a perspective view showing a partially disassembled wound electrode assembly. [Figure 3] This is an exploded perspective view showing a storage cell according to Embodiment 1. [Figure 4] This is another exploded perspective view showing the energy storage cell according to Embodiment 1. [Figure 5] This is a cross-sectional view of the energy storage cell according to Embodiment 2. [Modes for carrying out the invention]

[0010] Hereinafter, energy storage cells according to each embodiment of this 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 descriptions will not be repeated.

[0011] (Embodiment 1) Figure 1 is a cross-sectional view showing a power storage cell according to Embodiment 1. As shown in Figure 1, the power storage cell 1 according to Embodiment 1 of the present disclosure comprises a wound electrode body 10, a case 20, and a positive electrode current collector plate 30.

[0012] First, the wound electrode body 10 will be described. Figure 2 is a perspective view showing the wound electrode body in a partially disassembled state. As shown in Figures 1 and 2, the wound electrode body 10 is wound into a cylindrical shape. In Figure 2, the state in which the winding of the wound electrode body 10 has been slightly unwound is illustrated.

[0013] The wound electrode body 10 includes a positive electrode 11P, a negative electrode 11N, and a separator 12. In Embodiment 1, the negative electrode 11N is exemplified as the first electrode in this disclosure, and the positive electrode 11P is exemplified as the second electrode. The first electrode may be the positive electrode and the second electrode may be the negative electrode.

[0014] The positive electrode 11P and the negative electrode 11N have a sheet-like outer shape. The wound electrode body 10 is composed of a group of electrode plates in which the positive electrode 11P and the negative electrode 11N are wound around a separator 12.

[0015] The separator 12 is placed between the positive electrode 11P and the negative electrode 11N. The separator 12 separates the positive electrode 11P (positive electrode active material) and the negative electrode 11N (negative electrode active material) while allowing ions (for example, lithium ions) to move between them.

[0016] The positive electrode 11P includes a positive electrode current collector 111P and a positive electrode composite layer 112P. The positive electrode current collector 111P is made of, for example, aluminum.

[0017] The positive electrode composite layer 112P is coated on both radial surfaces of the positive electrode current collector 111P (the positive electrode coating part 111PA described later). The positive electrode composite layer 112P is in close contact with the separator 12. The positive electrode composite layer 112P is formed by coating the positive electrode slurry on the surface of the positive electrode current collector 111P and drying it. The positive electrode slurry is a slurry prepared by kneading the materials (such as positive electrode active material and binder) of the positive electrode composite layer 112P and a solvent. The thickness of the positive electrode composite layer 112P is, for example, 0.1 µm or more and 1000 µm or less.

[0018] The positive electrode current collector 111P includes a positive electrode coating part 111PA and a non-coated part 111PB of the positive electrode. The positive electrode coating part 111PA is the part of the positive electrode current collector 111P where the positive electrode composite layer 112P is coated. In other words, the positive electrode coating part 111PA is the part that is not exposed because it is covered by the positive electrode composite layer 112P.

[0019] The non-coated part 111PB of the positive electrode is the part of the positive electrode current collector 111P that is not covered by the positive electrode composite layer 112P and is exposed. The non-coated part 111PB of the positive electrode is located on the first direction Z1 side along the axial direction Z rather than the positive electrode coating part 111PA. Specifically, the non-coated part 111PB of the positive electrode protrudes from the positive electrode coating part 111PA toward the first direction Z1. The non-coated part 111PB of the positive electrode is bent inward in the radial direction around the winding axis α.

[0020] The non-coated part 111PB of the positive electrode includes a plurality of extension parts 111PC. The plurality of extension parts 11 1PC are arranged along the winding direction of the wound electrode body 10.

[0021] The negative electrode 11N includes a negative electrode current collector 111N and a negative electrode composite layer 112N. In Embodiment 1, the negative electrode current collector 111N is exemplified as the current collector in the present disclosure, and the negative electrode composite layer 112N is exemplified as the electrode composite layer in the present disclosure.

[0022] The negative electrode current collector 111N has a sheet-like outer shape. The negative electrode current collector 111N is made of, for example, copper.

[0023] The negative electrode composite layer 112N is formed on the negative electrode current collector 111N. Specifically, the negative electrode composite layer 112N is coated on both radial surfaces of the negative electrode current collector 111N (the negative electrode coated portion 111NA described later). The negative electrode composite layer 112N is in close contact with the separator 12. The negative electrode composite layer 112N is formed by coating the surface of the negative electrode current collector 111N with a negative electrode slurry and drying it. The negative electrode slurry is a slurry prepared by kneading the materials of the negative electrode composite layer 112N (such as negative electrode active material and binder) with a solvent. The thickness of the negative electrode composite layer 112N is, for example, 0.1 μm or more and 1000 μm or less.

[0024] The negative electrode current collector 111N includes a negative electrode coated portion 111NA and a negative electrode uncoated portion 111NB. The negative electrode coated portion 111NA is the part of the negative electrode current collector 111N to which the negative electrode composite material layer 112N is coated. In other words, the negative electrode coated portion 111NA is the part that is not exposed because it is covered by the negative electrode composite material layer 112N.

[0025] The uncoated negative electrode portion 111NB is the portion of the negative electrode current collector 111N that is not coated with the negative electrode composite layer 112N. In other words, the uncoated negative electrode portion 111NB is the portion of the negative electrode current collector 111N that is not covered by the negative electrode composite layer 112N and is exposed. The uncoated negative electrode portion 111NB is located on the side of the second direction Z2, which is axially aligned with the negative electrode coated portion 111NA. The second direction Z2 is the opposite direction to the first direction Z1. The uncoated negative electrode 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 uncoated negative electrode portion 111NB protrudes from the negative electrode coated portion 111NA to the side of the second direction Z2, which is axially aligned with the negative electrode coated portion 111NA. The uncoated negative electrode portion 111NB is bent radially inward with respect to the winding axis α.

[0026] The uncoated negative electrode portion 111NB includes a plurality of extensions 111NC. The plurality of extensions 111NC are aligned along the winding direction of the wound electrode body 10.

[0027] Next, we will describe Case 20. Figure 3 is an exploded perspective view showing a storage cell according to Embodiment 1. Figure 4 is another exploded perspective view showing a storage cell according to Embodiment 1.

[0028] As shown in Figures 1, 3, and 4, the case 20 houses the wound electrode body 10. The case 20 includes a positive electrode terminal 21P, a negative electrode terminal 21N, a cylindrical wall portion 22, a bottom portion 23, a sealing plug 24, an external gasket 25, and an internal gasket 26. In this embodiment, the negative electrode terminal 21N is exemplified as the external terminal in this disclosure.

[0029] The positive electrode terminal 21P is located on the first direction Z1 side of the wound electrode body 10. The positive electrode terminal 21P includes a disk portion 211 and a rivet portion 212. The disk portion 211 is exposed to the outside. The rivet portion 212 is connected to the disk portion 211. The rivet portion 212 extends from the center of the disk portion 211 when viewed from the axial direction Z. The rivet portion 212 is located approximately on the winding axis α of the wound electrode body 10. The rivet portion 212 extends in the second direction Z2. The positive electrode terminal 21P is formed of, for example, aluminum.

[0030] The negative electrode terminal 21N is positioned perpendicular to the axial direction Z. The negative electrode terminal 21N is provided with a through hole 21Nh. Therefore, the negative electrode terminal 21N has an annular outer shape when viewed from the axial direction Z. The negative electrode terminal 21N is located between the disk portion 211 and the wound electrode body 10 in the axial direction Z. The rivet portion 212 is inserted through the through hole 21Nh. The rivet portion 212 extends into the interior of the case 20. The material constituting the negative electrode terminal 21N is not particularly limited, but it is formed from aluminum, copper, or stainless steel, etc.

[0031] The cylindrical wall portion 22 is provided to cover the outer circumference of the wound electrode body 10. The cylindrical wall portion 22 covers the entire outer circumference of the wound electrode body 10. The cylindrical wall portion 22 has a cylindrical shape. The end of the cylindrical wall portion 22 on the first direction Z1 side is connected to the negative electrode terminal 21N. The negative electrode terminal 21N is integrally formed together with the cylindrical wall portion 22. The material constituting the cylindrical wall portion 22 is not particularly limited, but it is formed from a conductive material such as aluminum, copper, or stainless steel.

[0032] The bottom portion 23 is positioned on one side in the axial direction Z when viewed from the wound electrode body 10. When the negative electrode terminal 21N is connected to the other end of the cylindrical wall portion 22, it can be said that the bottom portion 23 is connected to one end of the cylindrical wall portion 22. Specifically, the bottom portion 23 is connected to the end of the cylindrical wall portion 22 on the second direction Z2 side.

[0033] The bottom portion 23 seals the opening of the cylindrical wall portion 22 on the second direction Z2 side. The bottom portion 23 is a sealing plate. The bottom portion 23 is welded to the cylindrical wall portion 22 so that the negative electrode 11N is electrically connected to the negative electrode terminal 21N via the bottom portion 23 and the cylindrical wall portion 22. The outer edge of the bottom portion 23 is connected to the cylindrical wall portion 22 by welding, such as laser welding. The material constituting the bottom portion 23 is not particularly limited, but it is formed from a conductive material such as aluminum, copper, or stainless steel.

[0034] The bottom portion 23 is joined to the unpainted negative electrode portion 111NB by welding from the outside of the case 20. As a result, the bottom portion 23 becomes negatively charged. The cylindrical wall portion joined to the bottom portion 23 also becomes negatively charged. The negative electrode terminal 21N connected to the cylindrical wall portion 22 also becomes negatively charged. Note that the energy storage cell 1 can also use the bottom portion 23 as the negative electrode terminal.

[0035] The bottom portion 23 has an annular projection 231, a plurality of radial projections 232, and a plurality of welded portions 233. The annular projection 231 extends in an annular shape around the winding axis α of the wound electrode body 10 when viewed from the axial direction Z. The annular projection 231 protrudes toward the first direction Z1. That is, the annular projection 231 protrudes toward the wound electrode body 10. The annular projection 231 is in contact with the uncoated negative electrode portion 111NB of the negative electrode 11N.

[0036] The multiple radial protrusions 232 are arranged apart from each other in the circumferential direction, centered on the winding axis α of the wound electrode body 10, when viewed from the axial direction Z. The multiple radial protrusions 232 are arranged at equal intervals in the circumferential direction.

[0037] Each of the multiple radially oriented protrusions 232 extends radially around the winding axis α of the wound electrode body 10. The radially oriented protrusions 232 are connected to the annular protrusions 231.

[0038] The radially protruding portion 232 protrudes toward the first direction Z1. That is, the radially protruding portion 232 protrudes toward the wound electrode body 10. The radially protruding portion 232 is in contact with the uncoated portion 111NB of the negative electrode 11N.

[0039] Multiple welded joints 233 are joined to the uncoated negative electrode portion 111NB at the bottom portion 23 by welding. This is the part that has been welded. Multiple welds 233 are formed by laser welding from the outside of the case 20. Multiple welds 233 are formed on the annular protrusion 231. On the annular protrusion 231, multiple welds 233 are formed to extend along the circumferential direction. Multiple welds 233 are formed on each of the multiple radial protrusions 232. On the radial protrusions 232, multiple welds 233 are formed to extend along the radial direction. The annular protrusion 231 and the multiple radial protrusions 232 may be thinner in thickness compared to other parts of the bottom 23. This makes it easier to form the welds 233.

[0040] A through-hole 23h is formed in the bottom portion 23. The through-hole 23h may be used to inject an electrolyte (not shown) contained within the case 20. The through-hole 23h is formed in the center of the bottom portion 23 when viewed from the axial direction Z.

[0041] The sealing plug 24 is inserted through a through hole 23h in the bottom 23. This secures the sealing plug 24 to the bottom 23. The sealing plug 24 and the through hole 23h can function as a pressure relief valve to release pressure inside the case 20 when the pressure inside the case 20 becomes excessively high.

[0042] The external gasket 25 is positioned between the positive terminal 21P and the negative terminal 21N. The external gasket 25 is made of an insulating material. Therefore, the external gasket 25 insulates the positive terminal 21P and the negative terminal 21N. The external gasket 25 covers the second direction Z2 side surface of the disk portion 211. The rivet portion 212 penetrates the external gasket 25 in the axial direction Z. The external gasket 25 covers the radial inner surface of the through hole 21Nh of the negative terminal 21N.

[0043] The internal gasket 26 covers the second direction Z2 side surface of the negative electrode terminal 21N. The internal gasket 26 is made of an insulating material. Therefore, the internal gasket 26 insulates the wound electrode body 10 from the negative electrode terminal 21N. The rivet portion 212 further penetrates the internal gasket 26 in the axial direction Z. Therefore, the rivet portion 212 is exposed inside the case 20.

[0044] Next, the positive electrode current collector plate 30 will be described. As shown in Figures 1 and 3, the positive electrode current collector plate 30 is located inside the case 20. The positive electrode current collector plate 30 is located on the first direction Z1 side of the wound electrode body 10.

[0045] The positive electrode current collector plate 30 is provided to electrically connect the positive electrode 11P and the positive electrode terminal 21P. The positive electrode current collector plate 30 is joined to the unpainted positive electrode portion 111PB of the positive electrode 11P by welding. As a result, the positive electrode current collector plate 30 is positively charged. The positive electrode current collector plate 30 is also joined to the end of the rivet portion 212 of the positive electrode terminal 21P on the second direction Z2 side by welding. As a result, the positive electrode terminal 21P is positively charged.

[0046] An internal gasket 26 is placed between the positive electrode current collector plate 30 and the negative electrode terminal 21N. This electrically insulates the positive electrode current collector plate 30 and the negative electrode terminal 21N from each other. Furthermore, the internal gasket 26 extends to the outer circumference of the positive electrode current collector plate 30. As a result, the internal gasket 26 is also placed between the positive electrode current collector plate 30 and the cylindrical wall portion 22. Therefore, the positive electrode current collector plate 30 and the cylindrical wall portion 22 are electrically insulated from each other.

[0047] The positive electrode current collector plate 30 has a roughly disc-shaped outer form. The positive electrode current collector plate 30 includes a central portion 31, an outer peripheral edge portion 32, a plurality of spokes 33, and a plurality of side portions 35.

[0048] The central portion 31 is positioned so as to overlap with the rivet portion 212 of the positive terminal 21P when viewed from the axial direction Z. The central part 31 is connected to the case 20, thereby electrically connecting the positive electrode current collector plate 30 to the positive electrode terminal 21P. Specifically, the central part 31 is joined to the rivet portion 212 of the positive electrode terminal 21P by welding.

[0049] The outer peripheral edge portion 32 is provided on the outer peripheral edge of the positive electrode current collector plate 30. The outer peripheral edge portion 32 is located on the outer peripheral side of the central portion 31. The outer peripheral edge portion 32 extends in an annular shape with the central portion 31 as the center. The outer peripheral edge portion 32 may be in contact with the unpainted positive electrode portion 111PB of the positive electrode 11P. However, the outer peripheral edge portion 32 is not joined to the unpainted positive electrode portion 111PB.

[0050] Multiple spokes 33 are spaced apart from each other. Multiple spokes 33 are arranged at equal intervals in the circumferential direction with respect to the central portion 31. The spokes 33 connect the central portion 31 and the outer edge portion 32. The spokes 33 have an outer shape such that their width is approximately equal from the central portion 31 to the outer edge portion 32.

[0051] The multiple side sections 35 are spaced apart from each other. The multiple side sections 35 are arranged at equal intervals in the circumferential direction with respect to the central section 31. The multiple spokes 33 and multiple side sections 35 are arranged such that the spokes 33 and side sections 35 alternate in the circumferential direction with respect to the central section 31.

[0052] The single piece 35 extends from the outer edge 32 toward the central part 31. The single piece 35 is connected to the positive electrode 11P. Specifically, the single piece 35 is joined to the unpainted positive electrode portion 111PB of the positive electrode 11P by welding. Figure 5 schematically shows the path PP on the positive electrode current collector plate 30 from the joint between the single piece 35 and the unpainted positive electrode portion 111PB to the joint between the central part 31 and the rivet portion 212.

[0053] The piece 35 has a fan-shaped portion 351 and a neck portion 352. The fan-shaped portion 351 is joined to the unpainted positive electrode portion 111PB of the positive electrode 11P by welding. The tip of the fan-shaped portion 351 faces the central portion 31. The fan-shaped portion 351 extends toward the outer peripheral edge portion 32 along two adjacent spokes 33 on both sides in the circumferential direction. This makes the surface area of ​​the fan-shaped portion 351 relatively large, facilitating welding to the unpainted positive electrode portion 111PB of the positive electrode 11P.

[0054] The neck portion 352 connects the outer peripheral edge portion 32 and the fan-shaped portion 351. The neck portion 352 may be in contact with the uncoated positive electrode portion 111PB of the positive electrode 11P. However, the neck portion 352 is not joined to the uncoated positive electrode portion 111PB of the positive electrode 11P. The circumferential dimension of the neck portion 352 is smaller than the circumferential dimension of the outer peripheral edge of the fan-shaped portion 351. This makes it easier for the side portion 35 to bend in the neck portion 352.

[0055] Here, an example of a welding method between the central portion 31 and the rivet portion 212 in this embodiment will be described. First, before the central portion 31 is welded to the rivet portion 212, the fan-shaped portion 351 of the side portion 35 is welded in advance to the unpainted positive electrode portion 111PB of the positive electrode 11P. 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. Then, while the welding device is pressed against the central portion 31 from the second direction Z2 side, the central portion 31 and the rivet portion 212 are welded to each other by the welding device. At this time, along the path PP, 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, bend significantly. As a result, the central portion 31 can be easily displaced in the axial direction Z relative to the side portion 35. Therefore, even if a welding device is pressed against the central portion 31, the displacement of the central portion 31 prevents the joint between the single portion 35 and the uncoated positive electrode portion 111PB from being destroyed. Consequently, the connection between the positive electrode current collector plate 30 and the case 20 becomes easier.

[0056] As described above, the energy storage cell 1 according to Embodiment 1 of the present disclosure comprises a wound electrode body 10 and a case The case 20 houses the wound electrode body 10. The case 20 includes a wound negative electrode 11N and a positive electrode 11P. The negative electrode 11N includes a sheet-like negative electrode current collector 111N and a negative electrode composite layer 112N formed on the negative electrode current collector 111N. The negative electrode current collector 111N includes a negative electrode coated portion 111NA coated with the negative electrode composite layer 112N and a negative electrode uncoated portion 111NB not coated with the negative electrode composite layer 112N. 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. The case 20 houses the wound electrode body 10. The case 20 includes a cylindrical wall portion 22 and a bottom portion 23. The cylindrical wall portion 22 is provided to cover the outer circumference of the wound electrode body 10. The bottom portion 23 is positioned on one side in the axial direction Z and is connected to one end of the cylindrical wall portion 22. The bottom portion 23 is joined to the uncoated negative electrode portion 111NB by welding from the outside of the case 20.

[0057] According to the above configuration, the bottom 23 of the case 20 has the function of collecting current from the negative electrode 11N. Therefore, a current collector plate, which is a different material from the case 20, is not required for the negative electrode 11N, and the number of components of the energy storage cell 1 can be reduced. As a result, the space available in the case 20 for accommodating the wound electrode body 10 is increased, and a larger wound electrode body 10 can be accommodated. Consequently, the energy density of the energy storage cell 1 is further improved.

[0058] Furthermore, in this embodiment, the case 20 further includes a negative electrode terminal 21N that is connected to the other end of the cylindrical wall portion 22 and is integrally formed with the cylindrical wall portion 22. The bottom portion 23 is welded to the cylindrical wall portion 22 such that the negative electrode 11N is electrically connected to the negative electrode terminal 21N via the bottom portion 23 and the cylindrical wall portion 22.

[0059] Even when the negative electrode terminal 21N is relatively far from the bottom portion 23 as in the above configuration, the negative electrode 11N can be electrically connected to the negative electrode terminal 21N via the bottom portion 23 without using any materials other than those used in the case 20. As a result, the energy density of the energy storage cell 1 can be increased.

[0060] (Embodiment 2) Next, a storage cell according to Embodiment 2 of this disclosure will be described. In Embodiment 2 of this disclosure, some of the configurations of Case 20 differ from those of Embodiment 1 of this disclosure. Therefore, the same configurations and effects as in Embodiment 1 of this disclosure will not be repeated in this description.

[0061] Figure 5 is a cross-sectional view of a storage cell according to Embodiment 2. As shown in Figure 5, in Embodiment 2 of this disclosure, the negative electrode terminal 21Na is joined to the other end of the cylindrical wall portion 22 by welding. The bottom portion 23a is integrally formed with the cylindrical wall portion 22 such that the negative electrode 11N is electrically connected to the negative electrode terminal 21Na via the bottom portion 23a and the cylindrical wall portion 22.

[0062] Even when the external terminal (negative electrode terminal 21Na) is relatively far from the bottom portion 23a as in the above configuration, the first electrode (negative electrode 11N) can be electrically connected to the external terminal (negative electrode terminal 21Na) via the bottom portion 23a without using any material other than that of the case 20. As a result, the energy density of the energy storage cell 1a can be increased. In this embodiment, the negative electrode terminal 21Na is exemplified as an external terminal in this disclosure.

[0063] Case 20 further includes an annular welded portion 27a. The annular welded portion 27a is formed by joining the cylindrical wall portion 22 and the negative electrode terminal 21Na to each other by laser welding or the like. When viewed from the axial direction Z, the annular welded portion 27a extends in an annular shape along the outer edge of the negative electrode terminal 21Na.

[0064] The embodiments disclosed herein should be considered in all respects to be illustrative and not restrictive. The scope of this disclosure is indicated by the claims rather than by the description of the embodiments above, and all modifications within the meaning and scope equivalent to the claims are included. This is intended to be the case. [Explanation of Symbols]

[0065] 1,1a Energy storage cell, 10 Winded electrode body, 11N Negative electrode, 111N Negative electrode current collector, 111NA Negative electrode coated part, 111NB Negative electrode uncoated part, 112N Negative electrode composite layer, 11P Positive electrode, 111P Positive electrode current collector, 111PA Positive electrode coated part, 111PB Positive electrode uncoated part, 112P Positive electrode composite layer, 12 Separator, 20 Case, 21N,21Na Negative electrode terminal, 21P Positive electrode terminal, 211 Disc part, 212 Rivet part, 22 Cylindrical wall part, 23,23a Bottom part, 231 Annular protrusion part, 232 Radial protrusion part, 233 Welded part, 24 Sealing plug, 25 External gasket, 26 Internal gasket, 27a Annular welded part, 30 Positive electrode current collector plate, 31 central part, 32 outer edge part, 33 spoke, 35 side part, 351 fan-shaped part, 352 neck part.

Claims

1. A wound electrode body including a wound first electrode and a wound second electrode, The device comprises a case for housing the aforementioned wound electrode body, The first electrode comprises a sheet-shaped current collector and an electrode composite layer formed on the current collector. The current collector includes a coated portion to which the electrode composite layer is applied and an uncoated portion to which the electrode composite layer is not applied. The uncoated portion protrudes from the coated portion to one side in the axial direction of the wound electrode body. The case includes a cylindrical wall portion provided to cover the outer circumference of the wound electrode body, and a bottom portion positioned on one side in the axial direction and connected to one end of the cylindrical wall portion. The bottom portion is joined to the unpainted portion by welding from the outside of the case, and is a power storage cell.

2. The case further includes an external terminal connected to the other end of the cylindrical wall portion and integrally formed with the cylindrical wall portion, The energy storage cell according to claim 1, wherein the bottom portion is joined to the cylindrical wall portion by welding such that the first electrode is electrically connected to the external terminal via the bottom portion and the cylindrical wall portion.

3. The case further includes an external terminal joined to the other end of the cylindrical wall by welding, The energy storage cell according to claim 1, wherein the bottom portion is integrally formed with the cylindrical wall portion such that the first electrode is electrically connected to the external terminal via the bottom portion and the cylindrical wall portion.

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