Energy storage cell

Abstract

To provide an energy storage cell that allows for a simplified configuration of the wound electrode body. [Solution] The energy storage cell 100 comprises a conductive winding core 90, a wound electrode body 10 including a first electrode sheet 10A and a second electrode sheet 10B wound around the winding core 90, and a first connecting member 50A and a second connecting member 50B positioned opposite the wound electrode body 10 in the Z direction in which the winding core 90 extends. The winding core 90 has a rectangular parallelepiped shape. The first electrode 91 of the winding core 90 is connected to the first electrode sheet 10A and the first connecting member 50A, respectively. The second electrode 92 of the winding core 90 is connected to the second electrode sheet 10B and the second connecting member 50B, respectively.

Description

Technical Field

[0001] The present disclosure relates to a storage battery cell.

Background Art

[0002] JP-T-2023-516411 (Patent Document 1) discloses a wound electrode assembly. The wound electrode assembly is formed by winding a positive electrode plate, a negative electrode plate, and a separator. The positive electrode plate and the negative electrode plate are each provided with a positive electrode tab portion and a negative electrode tab portion.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In Patent Document 1 described above, as described above, the positive electrode plate (electrode sheet) and the negative electrode plate (electrode sheet) are each provided with a positive electrode tab portion and a negative electrode tab portion. It is conceivable that the configuration of the electrode assembly (wound electrode body) becomes complicated by providing the positive electrode tab and the negative electrode tab.

[0005] The present disclosure has been made to solve the above problems, and an object thereof is to provide a storage battery cell capable of simplifying the configuration of a wound electrode body.

Means for Solving the Problems

[0006] A power storage cell according to one aspect of the present disclosure comprises a conductive winding core, a wound electrode body including an electrode sheet wound around the winding core, and a current collector positioned opposite the wound electrode body in the axial direction from which the winding core extends. The winding core has a rectangular parallelepiped shape and is connected to the electrode sheet and the current collector, respectively. The rectangular parallelepiped shape also includes a cubic shape. [Effects of the Invention]

[0007] According to this disclosure, the configuration of the wound electrode body can be simplified. [Brief explanation of the drawing]

[0008] [Figure 1] This is a perspective view showing the configuration of the energy storage device and frame members according to the first embodiment. [Figure 2] This is a perspective view showing the configuration of the energy storage cell according to the first embodiment. [Figure 3] This is an exploded perspective view showing the configuration of the energy storage cell according to the first embodiment. [Figure 4] This is a cross-sectional view of a wound electrode body according to the first embodiment. [Figure 5] This is a plan view showing the initial state of winding the first electrode sheet and the second electrode sheet according to the first embodiment. [Figure 6] This is a cross-sectional view showing a first modified example of the first embodiment. [Figure 7] This is a plan view showing a second modified example of the first embodiment. [Figure 8] This is a plan view showing a modified example of Figure 7. [Figure 9] This is a cross-sectional view showing the configuration of a storage cell according to the second embodiment. [Figure 10] This is a cross-sectional view along line XX in Figure 9. [Figure 11] This is a cross-sectional view showing the configuration of a storage cell according to the third embodiment. [Figure 12] This is a perspective view showing the starting state of the winding of the first electrode sheet and the second electrode sheet according to the third embodiment. [Figure 13]It is a perspective view showing the state at the start of winding of the first electrode sheet and the second electrode sheet according to a modification of the third embodiment. [Figure 14] It is a cross-sectional view showing the configuration of the power storage cell according to the fourth embodiment. [Figure 15] It is a perspective view showing the state at the start of winding of the first electrode sheet and the second electrode sheet according to the fourth embodiment. [Figure 16] It is a cross-sectional view showing the configuration of the power storage cell according to a modification of the present disclosure. [Figure 17] It is a diagram showing the power storage cell according to a modification of the present disclosure and the flow path through which the heat medium flows. [Figure 18] It is a diagram showing the wound electrode body and the electrode tab of the power storage cell according to a modification of the present disclosure.

Embodiments for Carrying Out the Invention

[0009] Embodiments of the present disclosure will be described with reference to the drawings. In the drawings referred to below, the same or corresponding members are denoted by the same reference numerals.

[0010] <First Embodiment> FIG. 1 is a perspective view showing the configuration of a power storage device 1 including a power storage cell 100 in an embodiment of the present disclosure. The power storage device 1 is mounted on, for example, a vehicle (not shown). Examples of the vehicle include a hybrid electric vehicle, a plug-in hybrid electric vehicle, and a battery electric vehicle. Note that the power storage device 1 may be provided in an electric device other than an electric vehicle (for example, a stationary power storage device).

[0011] In addition, the X-direction, Y-direction, and Z-direction in this specification are directions orthogonal to each other. For example, the X-direction and Y-direction may be the front-back direction and left-right direction, respectively, when the power storage device 1 is mounted on an electric vehicle. Also, the Z-direction may be the up-down direction. Specifically, the Z1-direction and Z2-direction may be the upward direction and downward direction, respectively. Note that the Z-direction is an example of the "axial direction" of the present disclosure.

[0012] The power storage device 1 is attached to a frame member 2 provided at the bottom of the vehicle. The frame member 2 is formed in a substantially rectangular prism shape surrounding the power storage device 1.

[0013] The power storage device 1 includes a plurality of power storage stacks 3. Each power storage stack 3 is formed in a rectangular parallelepiped shape long in the Y-direction. The plurality of power storage stacks 3 are arranged side by side along the X-direction. Each power storage stack 3 includes a plurality of power storage cells 100 arranged in the Y-direction. Note that in FIG. 1, for the sake of simplification, only two power storage stacks 3 are shown, and only three power storage cells 100 in each power storage stack 3 are shown.

[0014] FIG. 2 is a perspective view showing the power storage cell 100 according to the present embodiment. As shown in FIG. 2, the power storage cell 100 is a so-called square battery. The power storage cell 100 is a secondary battery configured to be capable of charging and discharging. The power storage cell 100 may be a secondary battery such as a lithium-ion battery or a nickel-metal hydride battery. The power storage cell 100 can be used, for example, as a cell included in a power storage module mounted on an electric vehicle.

[0015] The power storage cell 100 includes a wound electrode body 10, a case 20, a first external terminal 30A, a second external terminal 30B, a first terminal support portion 40A, and a second terminal support portion 40B. Note that in FIG. 2, the wound electrode body 10 is schematically shown by a broken line.

[0016] Case 20 is conductive. The conductive portion of Case 20 is made of a metal such as aluminum. Case 20 houses the wound electrode body 10 and the winding core portion 90, which will be described later. Case 20 also houses an electrolyte, which is not shown.

[0017] The case 20 includes a case body 21 and a lid 22. When viewed from a position P spaced apart from the winding core 90 (described later) in the Z direction, the case 20 has a rectangular shape. The case body 21 includes a bottom wall 210 and a peripheral wall 211 rising from the bottom wall 210.

[0018] The lid 22 includes a lid body 220 and an insulating cover 221. The lid body 220 is joined to the peripheral wall 211 by welding or the like so as to close the opening in the peripheral wall 211.

[0019] The first external terminal 30A and the second external terminal 30B are provided in the energy storage cell 100 so as to be exposed to the outside. In this embodiment, the first external terminal 30A is the positive terminal and the second external terminal 30B is the negative terminal. The first external terminal 30A and the second external terminal 30B are aligned in the X direction.

[0020] The first terminal support portion 40A is locked to the lid body 220. The first terminal support portion 40A supports the first external terminal 30A from the outer circumference side of the first external terminal 30A. The second terminal support portion 40B is locked to the lid body 220. The second terminal support portion 40B supports the second external terminal 30B from the outer circumference side of the second external terminal 30B.

[0021] Figure 3 is an exploded perspective view of the energy storage cell 100 according to this embodiment. The energy storage cell 100 further comprises a first connecting member 50A, a second connecting member 50B, a first sealing ring 60A, a second sealing ring 60B, an insulating member 70, a fuse protection section 80, and a winding core section 90. The first connecting member 50A and the second connecting member 50B are examples of the "current collector" of this disclosure.

[0022] The bottom wall 210 includes a bottom body 212, an outer protective film 213, and an inner protective film 214. The peripheral wall 211 rises from the bottom body 212. A pressure relief valve SV is provided in the bottom body 212. The outer protective film 213 covers the pressure relief valve SV from the outside. The inner protective film 214 covers the pressure relief valve SV from the inside. The bottom body 212 and the pressure relief valve SV are made of a metal such as aluminum.

[0023] An opening is formed at the upper end of the peripheral wall 211. The peripheral wall 211 has a substantially rectangular outer shape when viewed from the direction of the opening (position P (Figure 2)). The opening and the bottom wall 210 are aligned in the Z direction. The opening is located on the Z1 side of the bottom wall 210. The Z direction may be the height direction or vertical direction of the energy storage cell 100. The peripheral wall 211 is made of a metal such as aluminum.

[0024] The lid 22 further includes a sealing plug 222 and a plug cover 223. The lid body 220 has a first connecting hole 224A, a second connecting hole 224B, and an electrolyte injection hole 225. The electrolyte injection hole 225 is a through hole for injecting electrolyte into the case body 21 during the manufacturing process of the energy storage cell 100.

[0025] The sealing plug 222 seals the injection hole 225. The plug cover 223 covers the injection hole 225 and the sealing plug 222. The insulating cover 221 covers the injection hole 225, the sealing plug 222, and the plug cover 223.

[0026] The first connecting member 50A and the second connecting member 50B are conductive. At least a portion of the first connecting member 50A and the second connecting member 50B are located inside the case 20. Each of the first connecting member 50A and the second connecting member 50B is positioned opposite the wound electrode body 10 in the Z direction. Each of the first connecting member 50A and the second connecting member 50B is located on the Z1 side of the wound electrode body 10.

[0027] The first external terminal 30A or the first connecting member 50A is inserted through the first connecting hole 224A. The first external terminal 30A and the first connecting member 50A are joined to each other. The first connecting member 50A is joined to the wound electrode body 10. As a result, the first external terminal 30A is electrically connected to the wound electrode body 10.

[0028] The second external terminal 30B or the second connecting member 50B is inserted through the second connecting hole 224B. The second external terminal 30B and the second connecting member 50B are joined to each other. The second connecting member 50B is joined to the wound electrode body 10. As a result, the second external terminal 30B is electrically connected to the wound electrode body 10.

[0029] The first seal ring 60A is provided along the first connecting hole 224A. The first seal ring 60A is provided in the gap between the lid body 220 and the first external terminal 30A, and seals this gap. The second seal ring 60B is provided along the second connecting hole 224B. The second seal ring 60B is provided in the gap between the lid body 220 and the second external terminal 30B, and seals this gap. The first seal ring 60A and the second seal ring 60B have electrical insulating properties.

[0030] The first terminal support portion 40A includes a first locking ring 41A and a first covering ring 42A. The first locking ring 41A extends in an annular shape to surround the first connecting hole 224A and is directly locked to the lid body 220. The first covering ring 42A covers the first locking ring 41A. The first locking ring 41A supports the first external terminal 30A via the first covering ring 42A. The first covering ring 42A is made of a resin material that is electrically insulating or has relatively weak conductivity.

[0031] The second terminal support portion 40B includes a second locking ring 41B and a second covering ring 42B. The second locking ring 41B extends in an annular shape to surround the second connecting hole 224B and is directly locked to the lid body 220. The second covering ring 42B covers the second locking ring 41B. The second locking ring 41B supports the second external terminal 30B via the second covering ring 42B. The second covering ring 42B is made of an electrically insulating resin material.

[0032] The insulating member 70 has electrical insulating properties. The insulating member 70 is positioned between the wound electrode body 10 and the case 20. The insulating member 70 electrically insulates the wound electrode body 10 and the case 20 from each other. The insulating member 70 includes an insulating bracket 71, a circumferential insulating portion 72, a bottom insulating portion 73, and adhesive tape 74.

[0033] The insulating bracket 71 is positioned between the wound electrode body 10 and the lid body 220. The insulating bracket 71 is relatively rigid and is in contact with both the wound electrode body 10 and the lid body 220. As a result, the wound electrode body 10 is fixed to the case 20 in the Z direction.

[0034] The circumferential insulating portion 72 is positioned between the wound electrode body 10 and the circumferential wall 211. The wound electrode body 10 is made of a film-like material.

[0035] The bottom insulating portion 73 is positioned between the wound electrode body 10 and the bottom wall 210. The bottom insulating portion 73 is made of a film-like material. The bottom insulating portion 73 is fixed (adhered) to the case 20 (bottom wall 210) by adhesive tape 74.

[0036] The core portion 90 is conductive. The wound electrode body 10 is wound around the core portion 90. The wound electrode body 10 and the core portion 90 are electrically connected.

[0037] The core portion 90 extends in the Z direction. The core portion 90 protrudes from the upper end surface 101 of the wound electrode body 10 toward the Z1 side. The core portion 90 does not protrude toward the Z2 side from the lower end surface (not shown) of the wound electrode body 10 (see Figure 4).

[0038] The core portion 90 includes a metal first electrode 91, a metal second electrode 92, and an insulating layer 93. In this embodiment, the first electrode 91 is the positive electrode metal and may be made of, for example, aluminum. The second electrode 92 is the negative electrode metal and may be made of, for example, copper. The insulating layer 93 may be made of, for example, resin. The first electrode 91 and the second electrode 92 have the same shape and size as each other. Each of the first electrode 91 and the second electrode 92 has a rectangular parallelepiped shape. The insulating layer 93 insulates the first electrode 91 and the second electrode 92. The insulating layer 93 has a rectangular parallelepiped shape. Therefore, the core portion 90 has a rectangular parallelepiped shape. In this disclosure, the term "rectangular parallelepiped shape" has a broad meaning that also includes a cubic shape. Furthermore, the first electrode 91 and the second electrode 92 are examples of the "positive electrode metal" and "negative electrode metal" of this disclosure, respectively.

[0039] Figure 4 is a cross-sectional view of the wound electrode body 10 in the XZ plane. The wound electrode body 10 includes a first electrode sheet 10A and a second electrode sheet 10B. The first electrode sheet 10A and the second electrode sheet 10B have a sheet-like outer shape. The wound electrode body 10 is composed of an electrode plate group in which the first electrode sheet 10A and the second electrode sheet 10B are wound. Note that each of the first electrode sheet 10A and the second electrode sheet 10B is an example of an "electrode sheet" as disclosed herein.

[0040] In conventional energy storage cells, the wound electrode body and the current collector are electrically connected by connecting electrode tabs provided on the electrode sheet to the current collector (connecting member). In this case, the presence of electrode tabs can complicate the structure of the wound electrode body.

[0041] In the first embodiment, the first electrode 91 of the winding core 90 is connected to the first electrode sheet 10A and the first connecting member 50A, respectively. The second electrode 92 of the winding core 90 is connected to the second electrode sheet 10B and the second connecting member 50B, respectively.

[0042] This allows the first electrode sheet 10A and the first connecting member 50A to be electrically connected, and the second electrode sheet 10B and the second connecting member 50B to be electrically connected, without the need for electrode tabs. This simplifies the configuration of the wound electrode body 10.

[0043] Furthermore, because the core portion 90 has a rectangular parallelepiped shape, the outer shape of the wound electrode body 10 can be formed in a rectangular parallelepiped shape, thereby suppressing the formation of dead space between the corners of the wound electrode body 10 and the case 20. As a result, the volumetric efficiency of the wound electrode body 10 can be improved.

[0044] Referring again to Figure 4, the upper end surface 91a of the first electrode 91 is in contact with the lower surface 51A of the first connecting member 50A. The upper end surface 91a and the lower surface 51A may be joined by ultrasonic welding or the like. The upper end surface 92a of the second electrode 92 is in contact with the lower surface 51B of the second connecting member 50B. The upper end surface 92a and the lower surface 51B may be joined by ultrasonic welding or the like.

[0045] The first electrode sheet 10A is constructed by stacking a positive electrode sheet 11A, a separator 12A, a negative electrode sheet 13A, and a separator 14A in that order. Starting from the winding core 90 side, the positive electrode sheet 11A, separator 12A, negative electrode sheet 13A, and separator 14A are arranged in that order. The first electrode sheet 10A is fixed to the winding core 90 by the positive electrode sheet 11A being connected to the first electrode 91. This electrically connects the first electrode sheet 10A and the first electrode 91. Separators 12A and 14A are examples of the "first separator" and "second separator" of this disclosure, respectively. Also, the positive electrode sheet 11A and negative electrode sheet 13A are examples of the "first positive electrode sheet" and "first negative electrode sheet" of this disclosure, respectively.

[0046] The second electrode sheet 10B is constructed by stacking the negative electrode sheet 11B, separator 12B, positive electrode sheet 13B, and separator 14B in this order. Starting from the winding core 90 side, the negative electrode sheet 11B, separator 12B, positive electrode sheet 13B, and separator 14B are arranged in that order. The second electrode sheet 10B is fixed to the winding core 90 by the connection of the negative electrode sheet 11B to the second electrode 92. This electrically connects the second electrode sheet 10B and the second electrode 92. Separators 12B and 14B are examples of the "third separator" and "fourth separator" of this disclosure, respectively. Also, the negative electrode sheet 11B and positive electrode sheet 13B are examples of the "second negative electrode sheet" and "second positive electrode sheet" of this disclosure, respectively.

[0047] The outer edge of the separator 14A or separator 14B, which is positioned on the outermost circumference of the wound electrode body 10, is fixed by a tape member (not shown) in the winding direction.

[0048] In each of the positive electrode sheet 11A and positive electrode sheet 13B described above, a current collector (not shown) and a positive electrode active material layer (not shown) are laminated. In each of the negative electrode sheet 13A and negative electrode sheet 11B, a current collector (not shown) and a negative electrode active material layer (not shown) are laminated.

[0049] As shown in Figure 4, the first electrode sheet 10A and the second electrode sheet 10B are arranged alternately in a direction intersecting the Z direction (the X direction in Figure 4). The direction intersecting the Z direction (hereinafter sometimes referred to as the intersecting direction) means the direction away from the winding core 90 in the XY plane.

[0050] The first electrode sheet 10A and the second electrode sheet 10B, which are adjacent in the intersecting direction, are insulated by a separator 14A or separator 14B. This allows the first electrode sheet 10A and the second electrode sheet 10B to be insulated from each other while being wound around a common core 90.

[0051] The first electrode 91 and the second electrode 92 are arranged side by side with an insulating layer 93 in between, as viewed from position P (Figure 2). This allows the first electrode sheet 10A connected to the first electrode 91 and the second electrode sheet 10B connected to the second electrode 92 to be easily overlapped in the intersecting direction.

[0052] The first electrode 91 is positioned on the X1 side of the insulating layer 93. The second electrode 92 is positioned on the X2 side of the insulating layer 93. The insulating layer 93 is in contact with each of the first electrode 91 and the second electrode 92. In other words, there is no gap between the insulating layer 93 and each of the first electrode 91 and the second electrode 92.

[0053] Each of the above separators separates the positive and negative electrode sheets while allowing ions to move between adjacent positive and negative electrode sheets. These ions are, for example, lithium ions. Each separator has electrical insulating properties.

[0054] Figure 5 shows an example of the initial winding state of the first electrode sheet 10A and the second electrode sheet 10B. The first electrode 91 has a side surface 91b on the Y1 side, a side surface 91c on the Y2 side, and a side surface 91d connecting side surfaces 91b and 91c. Side surface 91d is the side surface opposite to the insulating layer 93. The second electrode 92 has a side surface 92b on the Y2 side, a side surface 92c on the Y1 side, and a side surface 92d connecting side surfaces 92b and 92c. Side surface 92d is the side surface opposite to the insulating layer 93. The insulating layer 93 has a side surface 93a on the Y1 side and a side surface 93b on the Y2 side.

[0055] The first electrode sheet 10A is joined to the side surface 91b of the first electrode 91 by ultrasonic welding or the like. The first electrode sheet 10A is wound from side surface 91b towards sides 91c and 91d (counterclockwise in Figure 5).

[0056] The second electrode sheet 10B is joined to the side surface 92b of the second electrode 92 by ultrasonic welding or the like. The second electrode sheet 10B is wound from side surface 92b towards sides 92c and 92d (counterclockwise in Figure 5).

[0057] The winding start end 15A of the first electrode sheet 10A is located at the boundary between the side surface 91b of the first electrode 91 and the side surface 93a of the insulating layer 93. The winding start end 15A may also be located on the side surface 93a. Similarly, the winding start end 15B of the second electrode sheet 10B is located at the boundary between the side surface 92b of the second electrode 92 and the side surface 93b of the insulating layer 93. The winding start end 15B may also be located on the side surface 93b. This makes it possible to prevent electrical conductivity between the second electrode sheet 10B and the first electrode 91, and also to prevent electrical conductivity between the first electrode sheet 10A and the second electrode 92.

[0058] The first electrode 91 has a corner portion 91e and a corner portion 91f. The corner portion 91e connects the side surface 91b and the side surface 91d. The corner portion 91f connects the side surface 91c and the side surface 91d. Each of the corner portions 91e and 91f may have a shape in which the sharp corners have been removed (smooth shape) by chamfering (R processing) or the like. This makes it possible to suppress the first electrode 91 from breaking due to damage caused by the corner portions 91e and 91f.

[0059] The second electrode 92 has a corner portion 92e and a corner portion 92f. The corner portion 92e connects the side surface 92b and the side surface 92d. The corner portion 92f connects the side surface 92c and the side surface 92d. Each of the corner portions 92e and 92f may be formed in the same manner as the corner portions 91e and 91f.

[0060] The first electrode sheet 10A has a portion 16A and a portion 17A. Portion 16A is the portion that contacts the corner 91e. Portion 17A is the portion that contacts the corner 91f. Each of portions 16A and 17A is formed such that the surface on the first electrode 91 side is recessed on the opposite side from the first electrode 91. This makes it possible to easily bend the first electrode sheet 10A.

[0061] The second electrode sheet 10B has a portion 16B and a portion 17B. Portion 16B is the portion that contacts the corner 92e. Portion 17B is the portion that contacts the corner 92f. Each of portions 16B and 17B is formed such that the surface on the second electrode 92 side is recessed on the side opposite to the second electrode 92.

[0062] <Modified form of the first embodiment> Figure 6 shows a first modified example of the first embodiment. In the first modified example, an air gap Ga is formed between the first electrode 91 and the second electrode 92 without an insulating layer being placed therein.

[0063] Figure 7 shows a second modified example of the first embodiment. The winding start end 15A of the first electrode sheet 10A is inserted into a recess 91g formed on the side surface 91d of the first electrode 91. The winding start end 15A is joined to the surface 91h that defines the recess 91g. The recess 91g may be filled with adhesive or the like. The corner portion 91i at the open end of the recess 91g may be formed into a smooth shape by chamfering (R processing) or the like.

[0064] Similarly, the winding start end 15B of the second electrode sheet 10B is also inserted into the recess 92g formed on the side surface 92d of the second electrode 92. Since the shape of the recess 92g is the same as that of the recess 91g, a detailed explanation is omitted.

[0065] An insulating sheet 94 is placed on the first electrode 91. The insulating sheet 94 spans the side surface 91b and the portion of the side surface 91d between the corner 91e and the recess 91g. An insulating sheet 95 is placed on the second electrode 92. The insulating sheet 95 spans the side surface 92b and the portion of the side surface 92d between the corner 92e and the recess 92g. This makes it possible to prevent electrical conductivity between the first electrode sheet 10A and the second electrode 92, and also to prevent electrical conductivity between the second electrode sheet 10B and the first electrode 91. Furthermore, it is possible to reduce the surface roughness of the first electrode 91 and the second electrode 92. Note that the insulating sheet 94 may extend from the side surface 93a of the insulating layer 93 to the recess 91g. The insulating sheet 95 may extend from the side surface 93b of the insulating layer 93 to the recess 92g.

[0066] Note that the locations where recesses are formed are not limited to the examples above. In the example shown in Figure 8, recess 191g is formed at the corner of the first electrode 91 on the insulating layer 93 side. Recess 192g is formed at the corner of the second electrode 92 on the insulating layer 93 side.

[0067] <Second Embodiment> Next, a storage cell 300 according to the second embodiment of this disclosure will be described. Components identical to those in the first embodiment will be denoted by the same reference numerals as in the first embodiment. Furthermore, components similar to those in the first embodiment will be described using the same names as in the first embodiment, and detailed descriptions may be omitted.

[0068] Figure 9 shows a cross-sectional view of the energy storage cell 300. The energy storage cell 300 comprises a wound electrode body 310, a case 320, and a winding core 390.

[0069] The core portion 390 is formed from a metal (for example, aluminum) on the positive electrode side. The core portion 390 has a substantially square shape when viewed from the Z direction. As a result, the outer shape of the wound electrode body 310 also has a substantially square shape. The case 320 also has a substantially square shape when viewed from the Z direction.

[0070] Figure 10 is a cross-sectional view along line XX in Figure 9. The wound electrode body 310 includes a first electrode sheet 10A and at least one negative electrode tab 311. In the second embodiment, there are multiple negative electrode tabs 311. The first electrode sheet 10A is wound around a winding core 390. The winding core 390 is in contact with the positive electrode sheet 11A of the first electrode sheet 10A. The electrode body 310 does not have a second electrode sheet 10B.

[0071] The case 320 includes a bottom wall 321, a peripheral wall 322, a top plate 323, an insulating seal 324, and a bottom insulating portion 325. The bottom wall 321 may be formed integrally with the peripheral wall 322. The top plate 323 is an example of a "current collector" as disclosed herein.

[0072] The upper end surface 391 of the winding core 390 is in contact with the top plate 323 of the case 320. As a result, the top plate 323 is positively charged.

[0073] Each of the multiple negative electrode tabs 311 connects the negative electrode sheet 13A to the bottom wall 321 of the case 320. As a result, both the bottom wall 321 and the peripheral wall 322 are negatively charged.

[0074] The bottom insulating portion 325 is positioned between the wound electrode body 310 (first electrode sheet 10A) and the bottom wall 321. The bottom insulating portion 325 has through holes 325a through which multiple negative electrode tabs 311 pass.

[0075] The insulating seal 324 surrounds the top plate 323 in a circumferential manner. The insulating seal 324 is formed in an annular shape. This electrically insulates the peripheral wall 322 from the top plate 323.

[0076] Furthermore, the winding core portion formed from the metal on the negative electrode side may be in contact with the case 320, and the positive electrode tab provided on the first electrode sheet 10A may also be in contact with the case 320.

[0077] <Third Embodiment> Figure 11 shows a power storage cell 400 according to the third embodiment of this disclosure. Note that components identical to those in the second embodiment will be denoted by the same reference numerals as in the second embodiment, and will not be described repeatedly.

[0078] The energy storage cell 400 comprises a wound electrode body 410, a case 320, and a winding core 490. The core portion 490 includes a first electrode 491, a second electrode 492, and an insulating layer 493. The first electrode 491 and the second electrode 492 are arranged side by side in the Z direction with the insulating layer 493 in between. The first electrode 491 is positioned on the Z1 side of the second electrode 492. The first electrode 491 and the second electrode 492 are examples of the "positive electrode metal" and "negative electrode metal" of this disclosure, respectively.

[0079] This configuration allows for a reduction in the length of the outer circumference of the core portion 490 when viewed from the Z direction, compared to the case where the first electrode 491 and the second electrode 492 are arranged side by side in the XY plane. As a result, the length of the electrode sheet forming the wound electrode body 410 in the winding direction can be reduced.

[0080] The upper end surface 491a of the first electrode 491 is in contact with the top plate 323 of the case 320. The lower end surface 492a of the second electrode 492 is in contact with the bottom wall 321 of the case 320. In the third embodiment and the fourth embodiment described later, the bottom wall 321 is an example of the "current collector" of this disclosure.

[0081] As shown in Figure 12, the wound electrode body 410 includes a first electrode sheet 410A and a second electrode sheet 410B. Figure 12 shows an example of the initial winding state of each of the first electrode sheet 410A and the second electrode sheet 410B. Note that each of the first electrode sheet 410A and the second electrode sheet 410B is an example of an "electrode sheet" as disclosed herein.

[0082] The first electrode 491 has a side surface 491b on the Y1 side. The second electrode 492 has a side surface 492b on the Y2 side. The first electrode sheet 410A may be connected (bonded) to side surface 491b. The second electrode sheet 410B may be connected (bonded) to side surface 492b.

[0083] The first electrode sheet 410A includes a narrow portion 411A, a wide portion 412A, and a connecting portion 413A. The narrow portion 411A covers the side surface 491b of the first electrode 491. The narrow portion 411A is connected (bonded) to the side surface 491b.

[0084] The wide portion 412A has a greater width in the Z direction than the narrow portion 411A. Specifically, the Z2-side end 414A of the narrow portion 411A is located closer to Z1 than the Z2-side end 415A of the wide portion 412A. The end 414A is located closer to Z1 than the insulating layer 493 in the Z direction. The end 414A may also be located within the range of the insulating layer 493 in the Z direction. The end 415A is located closer to Z1 than the lower end surface 492a of the second electrode 492 and closer to Z2 than the end 414B described later. The Z1-side ends of the narrow portion 411A, the wide portion 412A, and the connecting portion 413A are all located at the same position in the Z direction and are located closer to Z2 than the upper end surface 491a of the first electrode 491.

[0085] The connecting portion 413A connects the narrow portion 411A and the wide portion 412A. The width of the connecting portion 413A in the Z direction increases as it approaches the wide portion 412A. The Z2 side end 416A of the connecting portion 413A is inclined toward the Z2 side as it approaches the wide portion 412A. The inclination angle of the end 416A is set so that the connecting portion 413A of the first electrode sheet 410A wound around the winding core portion 490 does not come into contact with the second electrode 492. A bend radius may be formed at the connection between the end 416A and the end 414A.

[0086] The second electrode sheet 410B includes a narrow portion 411B, a wide portion 412B, and a connecting portion 413B. The narrow portion 411B covers the side surface 492b of the first electrode 491. The narrow portion 411B is connected (bonded) to the side surface 492b.

[0087] The wide portion 412B has a greater width in the Z direction than the narrow portion 411B. Specifically, the Z1-side end 414B of the narrow portion 411B is located Z2-side than the Z1-side end 415B of the wide portion 412B. The end 414B is located Z2-side of the insulating layer 493 in the Z direction. Note that the end 414B may be located within the range of the insulating layer 493 in the Z direction. The end 415B is located Z2-side of the upper end surface 491a of the first electrode 491 and Z1-side of the end 414A. Note that the Z2-side ends of the narrow portion 411B, the wide portion 412B, and the connecting portion 413B are all located in the same position in the Z direction and are located Z1-side of the lower end surface 492a of the second electrode 492.

[0088] The connecting portion 413B connects the narrow portion 411B and the wide portion 412B. The width of the connecting portion 413B in the Z direction increases as it approaches the wide portion 412B. The Z2 side end 416B of the connecting portion 413B is inclined toward the Z1 side as it approaches the wide portion 412B. The inclination angle of the end 416B is set so that the connecting portion 413B of the second electrode sheet 410B wound around the winding core portion 490 does not come into contact with the first electrode 491. A bend radius may be formed at the connection between the end 416B and the end 414B.

[0089] <Modified form of the third embodiment> Figure 13 is a perspective view showing a modified example of the third embodiment described above. In the modified example of Figure 13, the narrow portion 411A protrudes from the side surface 491b in the winding direction (towards X2 in Figure 13). Also, the narrow portion 411B protrudes from the side surface 492b in the winding direction (towards X1 in Figure 13).

[0090] <Fourth Embodiment> Figure 14 is a cross-sectional view showing a storage cell 500 according to the fourth embodiment of this disclosure. Components identical to those in the above embodiments will be denoted by the same reference numerals and will not be described repeatedly.

[0091] The energy storage cell 500 comprises a wound electrode body 10, a case 320, and a winding core 590. The winding core 590 includes a first electrode 591, a second electrode 592, and an insulating layer 593. Each of the first electrode 591 and the second electrode 592 is formed in an L-shape. The first electrode 591 and the second electrode 592 are combined to form a rectangular parallelepiped winding core 590. The first electrode 591 and the second electrode 592 are examples of the "positive electrode metal" and "negative electrode metal" of this disclosure, respectively.

[0092] The upper end surface 591a of the first electrode 591 is in contact with the top plate 323 of the case 320. The lower end surface 592a of the second electrode 592 is in contact with the bottom wall 321 of the case 320.

[0093] The first electrode 591 includes an upper end portion 591b and a downward extension portion 591c. The upper end portion 591b is the portion provided at the Z1-side end of the first electrode 591 and has an upper end surface 591a. The downward extension portion 591c extends from the X1-side end of the upper end portion 591b toward the Z2 side. The upper end portion 591b extends from the upper end of the downward extension portion 591c toward the X2 side.

[0094] The second electrode 592 includes a lower end portion 592b and an upward extension portion 592c. The lower end portion 592b is the portion provided at the Z2 side end of the second electrode 592 and has a lower end surface 592a. The upward extension portion 592c extends from the X2 side end of the lower end portion 592b toward the Z1 side. The lower end portion 592b extends toward the X1 side from the lower end of the upward extension portion 592c.

[0095] The insulating layer 593 includes an upper end 593a, a lower end 593b, and a connecting portion 593c. The upper end 593a is the portion of the insulating layer 593 provided at the Z1 side end. The lower end 593b is the portion of the insulating layer 593 provided at the Z2 side end end. The connecting portion 593c connects the upper end 593a and the lower end 593b. The upper end 593a extends from the upper end of the connecting portion 593c toward the X2 side. The upper end 593a extends to the X2 side surface 592d of the second electrode 592. The lower end 593b extends from the lower end of the connecting portion 593c toward the X1 side. The lower end 593b extends to the X1 side surface 591d of the first electrode 591.

[0096] The upper end portion 593a of the insulating layer 593 is positioned between the upper end portion 591b of the first electrode 591 and the upward extension portion 592c of the second electrode 592. The lower end portion 593b of the insulating layer 593 is positioned between the downward extension portion 591c of the first electrode 591 and the lower end portion 592b of the second electrode 592. The connecting portion 593c of the insulating layer 593 is positioned between the downward extension portion 591c and the upward extension portion 592c.

[0097] Figure 15 shows the state when the first electrode sheet 10A and the second electrode sheet 10B are each started to be wound onto the winding core 590. The starting end 15A of the first electrode sheet 10A is located on the Y1 side surface 594 of the winding core 590, in the portion where the connection portion 593c of the insulating layer 593 is exposed. The starting end 15B of the second electrode sheet 10B is located on the Y2 side surface 595 of the winding core 590, in the portion where the connection portion 593c is exposed.

[0098] Furthermore, the Z1-side end of the first electrode sheet 10A and the Z1-side end of the second electrode sheet 10B are provided in the Z-direction within the range where the upper end 593a of the insulating layer 593 is located. The Z2-side end of the first electrode sheet 10A and the Z2-side end of the second electrode sheet 10B are provided in the Z-direction within the range where the lower end 593b of the insulating layer 593 is located.

[0099] <Other variations> The energy storage cell 600 shown in Figure 16 comprises a wound electrode body 10, a case 320, and a winding core 690.

[0100] The core portion 690 includes a first electrode 691, a second electrode 692, and an insulating layer 693. Each of the first electrode 691 and the second electrode 692 is formed in the shape of a rectangular parallelepiped. The first electrode 691 and the second electrode 692 are arranged side by side in the X direction with the insulating layer 693 in between. The first electrode 691 and the second electrode 692 are examples of the "positive electrode metal" and "negative electrode metal" of this disclosure, respectively.

[0101] The upper end surface 691a of the first electrode 691 is in contact with the top plate 323 of the case 320. The lower end surface 692a of the second electrode 692 is in contact with the bottom wall 321 of the case 320.

[0102] The insulating layer 693 is sandwiched in the X direction by the first electrode 691 and the second electrode 692. The first electrode 691 protrudes Z1 side from the upper end 693a of the insulating layer 693. However, the first electrode 691 does not protrude Z2 side from the lower end 693b of the insulating layer 693. The second electrode 692 protrudes Z2 side from the lower end 693b of the insulating layer 693. However, the second electrode 692 does not protrude Z1 side from the upper end 693a of the insulating layer 693.

[0103] Figure 17 shows a power storage cell 700. The power storage cell 700 comprises a wound electrode body 410, a case 720, and a winding core 790.

[0104] The core portion 790 includes a first electrode 791, a second electrode 792, and an insulating layer 793. The first electrode 791 and the second electrode 792 are arranged side by side in the Z direction with the insulating layer 793 in between. The first electrode 791 and the second electrode 792 are examples of the "positive electrode metal" and "negative electrode metal" of this disclosure, respectively.

[0105] The upper end surface 791a of the first electrode 791 is in contact with the top plate 723 of the case 720. The lower end surface 792a of the second electrode 792 is in contact with the bottom wall 721 of the case 720.

[0106] A through-hole 794 extending in the Z direction is formed in the core portion 790. The through-hole 794 penetrates the first electrode 791, the insulating layer 793, and the second electrode 792 in the Z direction. The Z1 side opening end 794a of the through-hole 794 is formed on the upper end surface 791a. The Z2 side opening end 794b of the through-hole 794 is formed on the lower end surface 792a.

[0107] A through hole 720a is formed in the top plate 723. The through hole 720a communicates with the through hole 794 of the winding core portion 790 via its open end 794a. A through hole 721a is formed in the bottom wall 721. The through hole 721a communicates with the through hole 794 via its open end 794b.

[0108] The through-hole 720a in the top plate 723 is connected to the first end 1100 of the flow path 1000. The through-hole 721a in the bottom wall 721 is connected to the second end 1200 of the flow path 1000. A pump 1300 and a heat sink 1400 are provided in the portion of the flow path 1000 that is outside the energy storage cell 700. A heat transfer medium such as a coolant or a fire extinguishing liquid flows through the flow path 1000. The pump 1300 may be a water pump. Note that if a fire extinguishing liquid is flowing, the heat sink 1400 may not be provided. Alternatively, an inert gas may be flowed instead of a fire extinguishing liquid.

[0109] As a result, when a heat transfer medium such as a coolant flows through the flow path 1000, the energy storage cell 700 can be cooled and temperature variations within the energy storage cell 700 can be suppressed. When a fire extinguishing liquid (or inert gas) flows through the flow path 1000, the fire in the energy storage cell 700 can be extinguished. Alternatively, a liquid containing a fire extinguishing agent added to the heat transfer medium for cooling may be flowed through the flow path 1000.

[0110] Furthermore, the modified examples shown in Figure 17 may also be applied to the above embodiments and each of the above modified examples.

[0111] Figure 18 is a cross-sectional view showing a storage cell 800. The storage cell 800 includes a wound electrode body 510. The wound electrode body 510 differs from the wound electrode body 10 of the first embodiment in that it includes at least one positive electrode tab 511 and at least one negative electrode tab 512. In Figure 18, only one positive electrode tab 511 and one negative electrode tab 512 are shown, but there may be multiple positive electrode tabs 511 and negative electrode tabs 512. Note that each of the positive electrode tab 511 and the negative electrode tab 512 is an example of an "electrode tab" as described herein.

[0112] The positive electrode tab 511 is connected to the positive electrode sheet 11A of the first electrode sheet 10A. The positive electrode tab 511 protrudes from the positive electrode sheet 11A toward the first connecting member 50A side (Z1 side). Specifically, the positive electrode tab 511 protrudes from the outermost part of the positive electrode sheet 11A, rather than the innermost part. The positive electrode tab 511 is connected to the X1 side surface 91d of the first electrode 91.

[0113] The negative electrode tab 512 is connected to the negative electrode sheet 11B of the second electrode sheet 10B. The negative electrode tab 512 protrudes from the negative electrode sheet 11B toward the second connecting member 50B side (Z1 side). Specifically, the negative electrode tab 512 protrudes from the portion of the negative electrode sheet 11B that is on the outer circumference side rather than the portion located on the innermost circumference side. The negative electrode tab 512 is connected to the X2 side surface 92d of the second electrode 92.

[0114] With this configuration, the positive electrode tab 511 can improve the current collection efficiency on the positive electrode side. Furthermore, the negative electrode tab 512 can improve the current collection efficiency on the negative electrode side. Since the innermost positive electrode sheet 11A and the first electrode 91 are directly electrically connected, the desired current collection efficiency can be easily achieved even with a reduced number of positive electrode tabs 511 compared to the case where the innermost positive electrode sheet 11A and the first electrode 91 are not connected. Similarly, the desired current collection efficiency can be easily achieved even with a reduced number of negative electrode tabs 512 compared to the case where the innermost negative electrode sheet 11B and the second electrode 92 are not connected. Therefore, the configuration of the wound electrode body 510 can be easily simplified.

[0115] Furthermore, only one of the positive electrode tab 511 and the negative electrode tab 512 may be provided. Also, the modified example shown in Figure 18 may be applied to each of the modified examples described above. In addition, the positive electrode tab 511 may be directly connected to the first connecting member 50A. The negative electrode tab 512 may be directly connected to the second connecting member 50B.

[0116] In the embodiments and modifications described above, examples are shown in which the first electrode and the second electrode have the same shape and size. However, the disclosure is not limited thereto, and the first electrode and the second electrode may have different shapes and sizes.

[0117] In the embodiments and modifications described above, examples are shown in which the electrode sheet is directly wound around the electrode of the winding core, but the disclosure is not limited thereto. For example, a pretreatment may be performed to form an electrode layer on the surface of the electrode. The electrode sheet is wound over the electrode layer. This makes it possible to reduce the surface roughness of the electrode and to lower the resistance between the electrode and the electrode sheet.

[0118] The configurations of each of the above embodiments and each of the modified examples may be combined with each other. It should be noted that the embodiments disclosed herein are illustrative in all respects and not restrictive. The scope of this disclosure is defined by the claims rather than the description of the embodiments above, and includes all modifications within the meaning and scope equivalent to the claims. [Explanation of symbols]

[0119] 10, 310, 410 wound electrode body, 10A, 410A first electrode sheet (electrode sheet), 10B, 410B second electrode sheet (electrode sheet), 11A positive electrode sheet (first positive electrode sheet), 11B negative electrode sheet (second negative electrode sheet), 12A separator (first separator), 12B separator (third separator), 13A negative electrode sheet (first negative electrode sheet), 13B positive electrode sheet (second positive electrode sheet), 14A separator (second separator), 14B separator (fourth separator), 20, 320, 720 case, 50A first connecting member (current collector), 50B second connecting member (current collector), 90, 390, 490, 590, 690, 790 Core section, 91, 491, 591, 691, 791 First electrode (positive side metal), 92, 492, 592, 692, 792 Second electrode (negative side metal), 93, 493, 593, 693, 793 Insulating layer, 100, 300, 400, 500, 600, 700, 800 Energy storage cell, 321 Bottom wall (current collector), 323 Top plate (current collector), 511 Positive tab (electrode tab), 512 Negative tab (electrode tab), 794 Through hole, 1000 Flow path, P position.

Claims

1. A conductive core section, A wound electrode body including an electrode sheet wound around the aforementioned core portion, The winding core portion comprises a current collector positioned opposite to the winding electrode body in the axial direction from which the winding core portion extends, The winding core portion has a rectangular parallelepiped shape and is connected to the electrode sheet and the current collector, respectively, in a power storage cell.

2. The electrode sheet includes a first electrode sheet and a second electrode sheet. The first electrode sheet is constructed by stacking a first positive electrode sheet, a first separator, a first negative electrode sheet, and a second separator in this order. The aforementioned second electrode sheet is constructed by stacking a second negative electrode sheet, a third separator, a second positive electrode sheet, and a fourth separator in this order. The aforementioned winding core portion is The positive electrode metal and, The negative electrode metal and, It includes an insulating layer that insulates the positive electrode metal and the negative electrode metal, Each of the first electrode sheet and the second electrode sheet is wound around the core portion, The first electrode sheet is fixed to the core portion by the first positive electrode sheet being connected to the positive electrode side metal. The second electrode sheet is fixed to the core portion by the second negative electrode sheet being connected to the negative electrode side metal. In the intersecting direction that intersects the axial direction, the first electrode sheet and the second electrode sheet are arranged alternately. The energy storage cell according to claim 1, wherein the first electrode sheet and the second electrode sheet, which are adjacent in the intersecting direction, are insulated by the second separator or the fourth separator.

3. The energy storage cell according to claim 2, wherein the positive electrode metal and the negative electrode metal are arranged side by side with the insulating layer in between, when viewed from a position spaced apart from the winding core in the axial direction.

4. The energy storage cell according to claim 2, wherein the positive electrode metal and the negative electrode metal are arranged side by side in the axial direction with the insulating layer in between.

5. The wound electrode body includes an electrode tab that is electrically connected to the electrode sheet, The electrode tab is Protruding from the electrode sheet toward the current collector side, A storage cell according to any one of claims 1 to 4, connected to the aforementioned winding core.

6. The aforementioned winding core portion has a through hole extending in the axial direction, The energy storage cell according to any one of claims 1 to 4, wherein the through-hole is connected to a flow path through which a coolant or inert gas flows.

7. The case further comprises the aforementioned winding core and the aforementioned winding electrode body, The energy storage cell according to any one of claims 1 to 4, wherein the case has a rectangular shape when viewed from a position spaced apart from the winding core in the axial direction.

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