Energy storage device

Abstract

The energy storage device can prevent the exhaust valve from opening before the internal pressure of the housing case containing the energy storage cell installed in the device reaches a predetermined pressure. [Solution] The energy storage device 3 comprises a first electrode body 81, a second electrode body 91, and a housing case 20. The housing case 20 includes a first end plate 22a and a second end plate 21aa on which an exhaust valve 21ab is formed. The first electrode body 81 and the second electrode body 91 are arranged such that the first winding axis α1 and the second winding axis α2 pass through the first end plate and the second end plate. The first electrode body 81 has a first hollow portion S1 formed therein. The second electrode body 91 has a second hollow portion S2 formed therein. When the exhaust valve 21ab is viewed from the axial direction, it is positioned away from at least one of the first hollow portion S1 and the second hollow portion S2.

Description

Technical Field

[0001] The present disclosure relates to a power storage device.

Background Art

[0002] Power storage cells included in power storage devices have been proposed in various ways. For example, Japanese Unexamined Patent Application Publication No. 2014-154292 discloses a power storage cell having a housing case and an electrode body housed in the housing case. An exhaust valve is formed in the housing case.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The position of the exhaust valve disclosed in Japanese Unexamined Patent Application Publication No. 2014-154292 does not take into account the positional relationship with the winding center of the wound body among the electrode bodies housed in the power storage cell. When the internal pressure in the housing case increases due to gas generation from the electrode body, the pressure distribution in the housing case is non-uniform. In particular, the winding center portion is likely to become a gas flow portion when gas is ejected. Therefore, the internal pressure applied to the housing case near the winding center plane tends to be high, and by providing an exhaust valve in this portion, the exhaust valve can be immediately opened when the internal pressure in the housing case increases. On the other hand, if the exhaust valve is arranged so as to overlap with a plurality of winding center portions, in the housing case, exhaust gas is likely to be directly blown onto the exhaust valve, and there is a possibility that the exhaust valve may be opened before the internal pressure in the housing case reaches a predetermined pressure when viewed from the overall pressure distribution in the housing case.

[0005] This disclosure has been made in view of the above-mentioned problems, and its purpose is to provide an energy storage device that can suppress the opening of the exhaust valve before the internal pressure of the housing case of the energy storage cell mounted in the energy storage device reaches a predetermined pressure. [Means for solving the problem]

[0006] The energy storage device according to this disclosure comprises a first electrode body, a second electrode body, and a housing case. The first electrode body includes a first electrode sheet, a first separator, a second electrode sheet, and a second separator. The first electrode body is formed to surround a first winding axis extending in the axial direction. The second electrode body is arranged adjacent to the first electrode body and includes a third electrode sheet, a third separator, a fourth electrode sheet, and a fourth separator. The second electrode body is formed to surround a second winding axis extending in the axial direction. The housing case houses the first electrode body and the second electrode body. The housing case includes a first end plate and a second end plate on which an exhaust valve is formed. The first electrode body and the second electrode body are arranged such that the first winding axis and the second winding axis pass through the first end plate and the second end plate, respectively. The first electrode sheet is located on the inner circumference of the second electrode sheet in the first radial direction, which intersects the axial direction and is centered on the first winding axis. The third electrode sheet is located on the inner circumference of the fourth electrode sheet in the second radial direction, which intersects the axial direction and is centered on the second winding axis. The first electrode body includes a first winding end face located on the second end plate side and a second winding end face located on the first end plate side, and the first electrode body has a first hollow portion that extends from the first winding end face to the second winding end face. The first hollow portion is defined by the first electrode sheet, which is located on the innermost circumference in the first radial direction. The second electrode body includes a third winding end face located on the second end plate side and a fourth winding end face located on the first end plate side, and the second electrode body has a second hollow portion that extends from the third winding end face to the fourth winding end face. The second hollow portion is defined by the third electrode sheet, which is located on the innermost circumference in the second radial direction. When the exhaust valve, the first winding end face, and the third winding end face are viewed from the axial direction in a plan view, the exhaust valve is positioned away from at least one of the first hollow section and the second hollow section.

[0007] When the exhaust valve of the energy storage device according to this disclosure, the first winding end face, and the third winding end face are viewed from the axial direction in a plan view, the exhaust valve is positioned between the first hollow section and the second hollow section.

[0008] The second end plate of the energy storage device of this disclosure has an inner surface and an outer surface arranged in the axial direction. The outer surface is positioned away from the first electrode body and the second electrode body with respect to the inner surface. The outer surface has an outer edge portion that defines the outer edge of the outer surface. A first arc portion is formed at the side end of the first winding end surface. A second arc portion is formed at the side end of the third winding end surface. When the outer surface, the first winding end surface and the third winding end surface are viewed in plan in the axial direction, the outer edge portion, the first arc portion and the second arc portion define a gap region on the outer surface. The exhaust valve is positioned so as to overlap at least a portion with the gap region.

[0009] The energy storage device of this disclosure further comprises a cooler. The second end plate has an opening. The cooler does not face the opening in the axial direction. The exhaust valve faces at least a portion of the opening in the axial direction.

[0010] The second end plate of the energy storage device of this disclosure has an inner surface and an outer surface arranged in the axial direction, and a facing region defined within the outer surface. The outer surface is positioned away from the first electrode body and the second electrode body with respect to the inner surface. When the outer surface and the first wound end surface are viewed in plan from the axial direction, the facing region is the region where the outer surface and the first wound end surface overlap. The cooler is positioned opposite the facing region in the axial direction. The exhaust valve is positioned to avoid the facing region.

[0011] The first end plate of the energy storage device of this disclosure is provided with electrode terminals. The energy storage device of this disclosure is located below the bottom of the vehicle. The first end plate is located closer to the bottom than the second end plate. [Effects of the Invention]

[0012] According to the energy storage device described herein, it is possible to prevent the exhaust valve from opening before the internal pressure of the housing case of the energy storage cell mounted in the energy storage device reaches a predetermined pressure. [Brief explanation of the drawing]

[0013] [Figure 1] This is a schematic diagram showing a vehicle equipped with an energy storage device according to an embodiment of the present disclosure. [Figure 2] This is an exploded perspective view of the energy storage device in an embodiment of the present disclosure. [Figure 3] This is a perspective view of an energy storage cell in an embodiment of the present disclosure. [Figure 4] This is an exploded perspective view of a storage cell in an embodiment of the present disclosure. [Figure 5] Figure 3 is a cross-sectional view of the first electrode body housed in the energy storage cell, viewed in the direction of the VV arrow. [Figure 6] Figure 5 is an enlarged view of the first hollow section. [Figure 7] Figure 3 is a cross-sectional view of the second electrode body housed in the energy storage cell, viewed in the direction of the VII-VII arrow. [Figure 8] Figure 1 is an end view of the energy storage device as seen in the direction of the arrow VIII-VIII. [Figure 9] Figure 8 is a plan view of the outer surface of the bottom plate of the energy storage cell, seen from a position away from the bottom plate towards the cooler in the axial direction. [Figure 10] This is a plan view of a modified example 1 of the bottom plate of the energy storage cell in the embodiment of the present disclosure, viewed from a position away from the bottom plate towards the cooler side in the axial direction. [Figure 11] This is a plan view of a modified example 2 of the bottom plate of the energy storage cell in the embodiment of the present disclosure, viewed from a position away from the bottom plate towards the cooler in the axial direction. [Figure 12] This is a plan view of modified example 3 of the energy storage cell in the embodiment of the present disclosure, viewed from a position away from the bottom plate towards the cooler in the axial direction. [Figure 13] This is a plan view of modified example 4 of the energy storage cell in the embodiment of the present disclosure, viewed from a position away from the bottom plate towards the cooler in the axial direction.

Best Mode for Carrying Out the Invention

[0014] Hereinafter, embodiments and modified examples of the present disclosure will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals and their description will not be repeated. <Embodiment> FIG. 1 is a side view schematically showing a vehicle equipped with the power storage device according to the present embodiment. The vertical direction H shown in FIG. 1 indicates the vertical direction of the vehicle 1. The vertical direction H is the same direction as the axial direction A of the first winding axis α1 of the first electrode body 81 described orally. The width direction W indicates the width direction of the vehicle 1. The longitudinal direction D indicates the longitudinal direction of the vehicle 1.

[0015] The vehicle 1 includes a vehicle body 2 and a power storage device 3. The vehicle 1 includes, for example, a PHEV (Plug-in Hybrid Electric Vehicle), a BEV (Battery Electric Vehicle), or a FCEV (Fuel Cell Electric Vehicle). The power storage device 3 is disposed below the bottom 2a of the vehicle body 2.

[0016] FIG. 2 is an exploded perspective view of the power storage device in the present embodiment. The power storage device 3 includes a storage case 4, a power storage stack 15, and a cooler 13 shown in FIG. 10.

[0017] The storage case 4 includes an upper cover 5 and a lower case 6. The storage case 4 forms a storage space V defined by the upper cover 5 and the lower case 6.

[0018] The upper cover 5 is formed so as to cover the lower case 6 formed to open upward.

[0019] The lower case 6 includes a bottom wall 7 and a wall portion 8. The bottom wall 7 supports the power storage stack 15 in the vertical direction H. An opening 7a (see FIG. 8) described later is formed in the bottom wall 7. The opening 7a is disposed at a position facing an exhaust valve 21ab described later.

[0020] The wall portion 8 is formed to rise upward from the bottom wall 7 in the vertical direction H. The wall portion 8 has a peripheral wall 9 and a reinforcing portion 12. The peripheral wall 9 is formed to extend in a frame shape and to extend upward in the vertical direction H from the outer peripheral edge of the bottom wall 7. The peripheral wall 9 has a first side wall 10 and a second side wall 11. The first side wall 10 and the second side wall 11 are formed to extend in the front-rear direction D and are arranged with a gap between them in the width direction W.

[0021] The reinforcing portion 12 is formed to extend in the front-rear direction D. In the width direction W, the reinforcing portion 12 is positioned to pass through the center between the first side wall 10 and the second side wall 11.

[0022] The energy storage stack 15 is housed in the storage space V and is positioned on the upper surface of the bottom wall 7. The energy storage stack 15 is made up of a plurality of energy storage cells 100. The plurality of energy storage cells 100 are arranged in the front-to-back direction D. The energy storage cells 100 are formed in a rectangular parallelepiped shape that is elongated in the width direction W.

[0023] Figure 3 shows a perspective view of the energy storage cell 100. As shown in Figure 3, the energy storage cell 100 according to this embodiment is a so-called rectangular battery. The energy storage cell 100 may be a rechargeable secondary battery such as a lithium-ion battery or a nickel-metal hydride battery.

[0024] Figure 4 is an exploded perspective view of a battery according to an embodiment of the present disclosure. As shown in Figure 4, the energy storage cell 100 comprises a housing case 20, an insulating member 70, and a plurality of electrode bodies 80.

[0025] The housing case 20 is conductive. The housing case 20 is made of a metal such as aluminum. The housing case 20 houses a plurality of electrode bodies 80. The housing case 20 also houses an electrolyte solution, which is not shown in the figure. The housing case 20 includes a case body 21 and a top plate 22.

[0026] The case body 21 includes a bottom plate 21a and a peripheral wall 21b that rises from the bottom plate 21a. The bottom plate 21a is joined to the peripheral wall 21b at its outer peripheral edge.

[0027] The bottom plate 21a includes a bottom body 21aa and an exhaust valve 21ab. The bottom body 21aa is an example of the "second end plate" of this disclosure.

[0028] The exhaust valve 21ab is formed in the bottom body 21aa. The exhaust valve 21ab is a known exhaust valve. For example, the exhaust valve 21ab has a general section that is machined to be thinner than the bottom body 21aa. A fracture groove is formed in the general section of the exhaust valve 21ab. By appropriately designing this groove, the exhaust valve 21ab can be selectively fractured by a small increase in pressure inside the housing case 20. The groove is formed, for example, by a die and a punch. When viewed in plan in the axial direction A, the groove is formed in an elliptical or linear shape.

[0029] The peripheral wall 21b rises from the base body 21aa. An opening is formed at the upper end of the peripheral wall 21b. The peripheral wall 21b has a roughly rectangular shape when viewed from the vertical direction H. The peripheral wall 21b and the base plate 21a are aligned in the vertical direction H. The peripheral wall 21b is made of a metal such as aluminum.

[0030] The top plate 22 includes a top plate body 22a, a sealing plug 22b, a plug cover 22c, an insulating cover 22d, and electrode terminals 22e. The top plate body 22a is an example of the "first end plate" of this disclosure.

[0031] The top plate body 22a is joined to the peripheral wall 21b by welding or other means so as to close the opening in the peripheral wall 21b. Electrode terminals 22e are provided on the top plate body 22a. The top plate body 22a has a first connecting hole 22aa, a second connecting hole 22ab, and an electrolyte injection hole 22ac. The electrolyte injection hole 22ac is a through hole for injecting electrolyte into the case body 21 during the manufacturing process of the energy storage cell 100. The top plate body 22a is positioned closer to the bottom 2a of the vehicle body 2 than to the bottom body 21aa.

[0032] The sealing plug 22b seals the injection hole 22ac. The plug cover 22c covers the injection hole 22ac and the sealing plug 22b. The insulating cover 22d covers the injection hole 22ac, the sealing plug 22b, and the plug cover 22c.

[0033] The electrode terminal 22e includes a first external terminal 30A, a second external terminal 30B, a first connecting member 40A, a second connecting member 40B, a first sealing ring 50A, a second sealing ring 50B, a first terminal support portion 60A, and a second terminal support portion 60B.

[0034] 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.

[0035] The first connecting member 40A and the second connecting member 40B are electrically conductive. At least a portion of the first connecting member 40A and the second connecting member 40B are located inside the housing case 20.

[0036] The first external terminal 30A or the first connecting member 40A is inserted through the first connecting hole 22aa. The first external terminal 30A and the first connecting member 40A are joined to each other. The first connecting member 40A is electrically connected to the electrode body 80. Thus, the first external terminal 30A is electrically connected to the electrode body 80.

[0037] The second external terminal 30B or the second connecting member 40B is inserted through the second connecting hole 22ab. The second external terminal 30B and the second connecting member 40B are joined to each other. The second connecting member 40B is electrically connected to the electrode body 80. As a result, the second external terminal 30B is electrically connected to the electrode body 80.

[0038] The first seal ring 50A is provided along the first connecting hole 22aa. The first seal ring 50A is provided in the gap between the top plate body 22a and the first external terminal 30A, and seals this gap. The second seal ring 50B is provided along the second connecting hole 22ab. The second seal ring 50B is provided in the gap between the top plate body 22a and the second external terminal 30B, and seals this gap. The first seal ring 50A and the second seal ring 50B have electrical insulating properties.

[0039] The first terminal support portion 60A is locked to the top plate body 22a. The first terminal support portion 60A supports the first external terminal 30A from the outer circumference of the first external terminal 30A. The first terminal support portion 60A includes a first locking ring 61A and a first covering ring 62A. The first locking ring 61A extends in an annular shape so as to surround the first connecting hole 22aa and is locked directly to the top plate body 22a. The first covering ring 62A covers the first locking ring 61A. The first locking ring 61A supports the first external terminal 30A via the first covering ring 62A. The first covering ring 62A is made of an electrically insulating resin material.

[0040] The second terminal support portion 60B is locked to the top plate body 22a. The second terminal support portion 60B supports the second external terminal 30B from the outer circumference of the second external terminal 30B. The second terminal support portion 60B includes a second locking ring 61B and a second covering ring 62B. The second locking ring 61B extends in an annular shape so as to surround the second connecting hole 22ab and is locked directly to the top plate body 22a. The second covering ring 62B covers the second locking ring 61B. The second locking ring 61B supports the second external terminal 30B via the second covering ring 62B. The second covering ring 62B is made of an electrically insulating resin material.

[0041] The insulating member 70 has electrical insulating properties. The insulating member 70 is positioned between the electrode body 80 and the housing case 20. The insulating member 70 electrically insulates the electrode body 80 and the housing case 20 from each other. The insulating member 70 includes an insulating bracket 71, a circumferential insulating portion 72, and a bottom insulating portion 73.

[0042] The insulating bracket 71 is positioned between the electrode body 80 and the top plate body 22a. The insulating bracket 71 is relatively rigid and is in contact with both the electrode body 80 and the top plate body 22a. This fixes the electrode body 80 to the housing case 20 in the vertical direction H. The circumferential insulating portion 72 is positioned between the electrode body 80 and the circumferential wall 21b. The circumferential insulating portion 72 is made of a film-like material. The bottom insulating portion 73 is positioned between the electrode body 80 and the bottom plate 21a. The bottom insulating portion 73 is made of a film-like material. In this embodiment, the bottom insulating portion 73 is bonded to the electrode body 80.

[0043] The electrode body 80 is a so-called wound electrode body. Typically, the electrode body 80 has a first electrode body 81 and a second electrode body 91. The first electrode body 81 and the second electrode body 91 are arranged adjacent to each other in the front-to-back direction D. The circumferential insulating portion 72 may integrally cover the electrode body 80 so that the first electrode body 81 and the second electrode body 91 are fixed to each other.

[0044] The first electrode body 81 has a first tab 151A and a second tab 151B. The second electrode body 91 has a first tab 152A and a second tab 152B. The first tab 151A electrically connects the first electrode sheet 82, described later, which is on the first electrode body 81, to the first connecting member 40A. The second tab 151B electrically connects the second electrode sheet 83, described later, which is on the first electrode body 81, to the second connecting member 40B. The first tab 152A electrically connects the second electrode sheet 83, described later, which is on the second electrode body 91, to the first connecting member 40A. The second tab 152B electrically connects the second electrode sheet 83, described later, which is on the second electrode body 91, to the second connecting member 40B.

[0045] The first tab 151A and the first tab 152A are arranged side by side in the front-to-back direction D. The first tabs 151A and 152A are joined to each other, for example by ultrasonic welding. The first tabs 151A and 152A are joined to the first connecting member 40A, for example by ultrasonic welding. The second tab 151B and the second tab 152B are arranged side by side in the front-to-back direction D. The second tabs 151B and 152B are joined to each other, for example by ultrasonic welding. The second tabs 151B and 152B are joined to the second connecting member 40B, for example by ultrasonic welding.

[0046] The details of the first electrode body 81 will be explained below with reference to Figure 5. Figure 5 is an end view of the first electrode body 81 housed in the energy storage cell 100 shown in Figure 3, viewed in the direction of the VV arrow.

[0047] The first electrode body 81 includes a first electrode sheet 82, a second electrode sheet 83, a first separator 84A, a second separator 84B, and a tape member 85. The first electrode sheet 82, the second electrode sheet 83, the first separator 84A, and the second separator 84B all have a sheet-like outer shape. The first electrode sheet 82, the second electrode sheet 83, the first separator 84A, and the second separator 84B together are referred to as a sheet group. The first electrode body 81 is formed by winding the first electrode sheet 82 and the second electrode sheet 83 around a first winding axis α1 via the first separator 84A and the second separator 84B. In other words, the first electrode body 81 is a so-called wound electrode body. Here, the first winding axis α1 is the axis of the first electrode body 81 extending in the axial direction A, and in this embodiment, the axial direction A is the same direction as the vertical direction H. The first electrode body 81 intersects with the axial direction A and is formed so as to surround the first winding axis α1 from the inner circumference side in the first radial direction R1 centered on the first winding axis α1, in the order of first separator 84A, first electrode sheet 82, second separator 84B, and second electrode sheet 83. As a result, the first electrode body 81 has a first hollow portion S1 centered on the first winding axis α1. More specifically, in this embodiment, the first electrode sheet 82 is located on the inner circumference side of the second electrode sheet 83 in the first radial direction R1, and as shown in Figure 6, the first hollow portion S1 is defined by the first electrode sheet 82 which is located on the innermost circumference side in the first radial direction R1.

[0048] The first electrode sheet 82 includes a first current collector 82A and a first active material layer 82B. The second electrode sheet 83 includes a second current collector 83A and a second active material layer 83B. In this embodiment, the first electrode sheet 82 is the positive electrode and the second electrode sheet 83 is the negative electrode. However, the first electrode sheet 82 may be the negative electrode and the second electrode sheet 83 may be the positive electrode.

[0049] The first separator 84A and the second separator 84B separate the first electrode sheet 82 and the second electrode sheet 83 while allowing ions to pass between them. These ions are, for example, lithium ions. The first separator 84A and the second separator 84B are electrically insulating. The first separator 84A is located on the innermost side in the first radial direction R1. On the other hand, the second separator 84B is located on the outermost side in the first radial direction R1. The outer edge of the second separator 84B in the first radial direction R1 is fixed by a tape member 85 placed on the outer surface of the second separator 84B.

[0050] The details of the second electrode body 91 will be explained below with reference to Figure 7. Note that the first electrode body 81 and the second electrode body 91 have substantially the same configuration. Figure 7 is a cross-sectional view of the second electrode body 91 housed in the energy storage cell 100 shown in Figure 3, viewed in the direction of the VII-VII arrow.

[0051] The second electrode body 91 includes a third electrode sheet 92, a fourth electrode sheet 93, a third separator 94A, a fourth separator 94B, and a tape member 95. The third electrode sheet 92, the fourth electrode sheet 93, the third separator 94A, and the fourth separator 94B all have a sheet-like outer shape. The third electrode sheet 92, the fourth electrode sheet 93, the third separator 94A, and the fourth separator 94B together are referred to as a sheet group. The second electrode body 91 is formed by winding the third electrode sheet 92 and the fourth electrode sheet 93 around the second winding axis α2 via the third separator 94A and the fourth separator 94B. In other words, the second electrode body 91 is a so-called wound electrode body. Here, the second winding axis α2 is the axis of the second electrode body 91 extending in the axial direction A, and in this embodiment, the axial direction A is the same direction as the vertical direction H. The second electrode body 91 intersects with the axial direction A and is formed so as to surround the second winding axis α2 from the inner circumference side in the second radial direction R2 centered on the second winding axis α2, in the order of third separator 94A, third electrode sheet 92, fourth separator 94B, and fourth electrode sheet 93. As a result, a second hollow portion S2 is formed in the second electrode body 91 centered on the second winding axis α2. More specifically, in this embodiment, the third electrode sheet 92 is located on the inner circumference side of the fourth electrode sheet 93 in the second radial direction R2, and the second hollow portion S2 is defined by the third electrode sheet 92 which is located on the innermost circumference side in the second radial direction R2.

[0052] The third electrode sheet 92 includes a third current collector 92A and a third active material layer 92B. The fourth electrode sheet 93 includes a fourth current collector 93A and a fourth active material layer 93B.

[0053] The third separator 94A and the fourth separator 94B separate the third electrode sheet 92 and the fourth electrode sheet 93 while allowing ions to pass between them. These ions are, for example, lithium ions. The third separator 94A and the fourth separator 94B are electrically insulating. The third separator 94A is located on the innermost side in the second radial direction R2. On the other hand, the fourth separator 94B is located on the outermost side in the second radial direction R2. The outer edge of the fourth separator 94B in the second radial direction R2 is fixed by a tape member 95 placed on the outer surface of the fourth separator 94B.

[0054] Figure 8 is an end view of the energy storage device shown in Figure 1, viewed in the direction of the arrow VIII-VIII. Inside the housing case 20, the first electrode body 81 and the second electrode body 91 are arranged such that the first winding axis α1 and the second winding axis α2 pass through the top plate 22 and the bottom plate 21a.

[0055] The first electrode body 81 has a first winding end face 86 and a second winding end face 87. The first winding end face 86 and the second winding end face 87 are spaced apart in the axial direction A. The first winding end face 86 is located on the bottom plate 21a side. The second winding end face 87 is located on the top plate 22 side. Here, the first hollow portion S1 is formed to extend from the first winding end face 86 to the second winding end face 87.

[0056] The second electrode body 91 has a third winding end face 96 and a fourth winding end face 97. The third winding end face 96 and the fourth winding end face 97 are spaced apart in the axial direction A. The third winding end face 96 is located on the bottom plate 21a side. The fourth winding end face 97 is located on the top plate 22 side. Here, the second hollow portion S2 is formed to extend from the third winding end face 96 to the fourth winding end face 97.

[0057] The bottom plate 21a of the case body 21 has an inner surface 21ac and an outer surface 21ad. The inner surface 21ac and the outer surface 21ad are spaced apart in the axial direction A. The inner surface 21ac is located on the electrode body 80 side relative to the outer surface 21ad. The outer surface 21ad is located on the bottom wall 7 side relative to the inner surface 21ac. The outer surface 21ad is located away from the first electrode body 81 and the second electrode body 91 relative to the inner surface 21ac. The outer surface 21ad has a facing region 21ae. The facing region 21ae is a region defined within the outer surface 21ad, and is also the region where the outer surface 21ad and the first winding end surface 86 overlap when viewed from the axial direction A in a plan view.

[0058] An opening 7a is formed in the bottom wall 7 of the storage case 4. The opening 7a is positioned opposite the exhaust valve 21ab. The energy storage device 3 includes a cooler 13. The cooler 13 is provided in the bottom wall 7. In the vertical direction H, the cooler 13 is positioned on the opposite side from the energy storage cells 100 with respect to the bottom wall 7. More specifically, in the axial direction A, the cooler 13 is positioned opposite the opposing region 21ae, with the bottom wall 7 in between. Note that when the cooler 13 is positioned opposite the opposing region 21ae, it means that when the cooler 13 and the opposing region 21ae are viewed in plan from the axial direction A, at least a part of the cooler 13 overlaps with the opposing region 21ae. In this embodiment, the cooler 13 cools the multiple energy storage cells 100 of the energy storage stack 15. A cooling medium (oil, etc.) flows inside the cooler 13.

[0059] The storage case 4 further has a shear panel 14. The shear panel 14 is located on the opposite side of the energy storage cell 100 in the vertical direction H, with respect to the bottom wall 7. The shear panel 14 is provided on the bottom wall 7 with the cooler 13 in between. The shear panel 14 has the function of protecting the lower case 6. The shear panel 14 may be formed in a flat plate shape.

[0060] Figure 9 is a plan view of the outer surface of the bottom plate of the energy storage cell shown in Figure 8, viewed from a position away from the bottom plate towards the cooler in the axial direction.

[0061] The first wound end face 86 of the first electrode body 81 has a pair of first arc portions 86a and a pair of first straight portions 86b. The pair of first arc portions 86a and the pair of first straight portions 86b form the outer edge of the first wound end face 86. Each of the pair of first arc portions 86a is located at the side end of the first wound end face 86 and is spaced apart in the width direction W. Each of the pair of first straight portions 86b is spaced apart in the front-rear direction D. One of the pair of first straight portions 86b connects one end of the pair of first arc portions 86a to the other end of the pair of first arc portions 86a. The other of the pair of first straight portions 86b connects the other end of one of the pair of first arc portions 86a to the other end of the pair of first arc portions 86a.

[0062] The third winding end face 96 of the second electrode body 91 has a pair of second arc portions 96a and a pair of second straight portions 96b. The pair of second arc portions 96a and the pair of second straight portions 96b form the outer edge of the third winding end face 96. Each of the pair of second arc portions 96a is located at the side end of the third winding end face 96 and is spaced apart in the width direction W. Each of the pair of second straight portions 96b is spaced apart in the front-rear direction D. One of the pair of second straight portions 96b connects one end of the pair of second arc portions 96a to the other end of the pair of second arc portions 96a. The other of the pair of second straight portions 96b connects the other end of one of the pair of second arc portions 96a to the other end of the pair of second arc portions 96a.

[0063] The outer surface 21ad of the bottom plate 21a has an outer edge portion 21af that defines the outer edge of the outer surface 21ad. When the outer surface 21ad, the first winding end face 86, and the third winding end face 96 are viewed from a plane direction A, the region on the outer surface 21ad defined by the outer edge portion 21af, the first arc portion 86a, and the second arc portion 96a is called the gap region G.

[0064] The first electrode body 81 has a first hollow portion S1 formed around a first winding axis α1 and a first winding end face 86. The second electrode body 91 has a second hollow portion S2 formed around a second winding axis α2 and a third winding end face 96. An exhaust valve 21ab is provided on the bottom plate 21a of the housing case 20 that houses the first electrode body 81. An opposing region 21ae is defined on the outer surface 21ad of the bottom plate 21a.

[0065] When the exhaust valve 21ab and the first winding end face 86 and the third winding end face 96 are viewed from the axial direction A, the exhaust valve 21ab in this embodiment is positioned away from the first hollow portion S1. More specifically, the exhaust valve 21ab is positioned to avoid the opposing region 21ae. Here, when the exhaust valve 21ab is positioned away from the first hollow portion S1, it means that when the exhaust valve 21ab and the first hollow portion S1 are viewed from the axial direction A, the center of the exhaust valve 21ab does not overlap with the first hollow portion S1. Furthermore, when the exhaust valve 21ab is positioned to avoid the opposing region 21ae, it means that when the exhaust valve 21ab and the opposing region 21ae are viewed from the axial direction A, the center of the exhaust valve 21ab does not overlap with the opposing region 21ae.

[0066] Furthermore, the exhaust valve 21ab may be positioned such that it does not overlap with at least one of the first hollow section S1 and the second hollow section S2 in any way.

[0067] Generally, gas is generated from the electrode body 80 when the energy storage cell 100 is used. When the internal pressure inside the housing case 20 increases due to the gas generation from the electrode body 80, the pressure distribution inside the housing case 20 is uneven. The first hollow section S1 and the second hollow section S2 tend to become areas where gas flows when gas is ejected. Therefore, the internal pressure on the housing case 20 facing the first hollow section S1 and the second hollow section S2 tends to increase.

[0068] Here, we will describe the case where the exhaust valve is arranged to overlap with multiple winding centers (the first hollow section S1 and the second hollow section S2 in this embodiment). In this case, when gas is generated from the first electrode body 81 and the second electrode body 91, both the gas ejected from the first hollow section S1 and the second hollow section S2 will be blown onto the exhaust valve. As a result, there is a risk that the exhaust valve will open before the internal pressure inside the housing case 20 reaches a predetermined pressure.

[0069] On the other hand, in the energy storage device 3 according to this embodiment, the exhaust valve 21ab is positioned away from the first hollow section S1. With this configuration, even if gas is generated from the first electrode body 81 and the second electrode body 91, it is possible to suppress the gas from the first hollow section S1 from being blown onto the exhaust valve 21ab. This makes it possible to suppress the opening of the exhaust valve 21ab before the internal pressure inside the housing case reaches a predetermined internal pressure.

[0070] With this configuration, it is possible to prevent the exhaust valve 21ab from opening before the internal pressure of the housing case 20 of the energy storage cell 100 mounted on the energy storage device 3 reaches a predetermined pressure.

[0071] Although an example has been shown in which the exhaust valve 21ab is positioned away from the first hollow section S1, the embodiments of this disclosure are not limited to this. For example, the exhaust valve 21ab may be positioned away from at least one of the first hollow section S1 and the second hollow section S2. For example, if the exhaust valve is positioned so as to overlap both the first hollow section S1 and the second hollow section S2, there is a risk that gas from both the first hollow section S1 and the second hollow section S2 may be blown onto the exhaust valve 21ab. On the other hand, if the exhaust valve 21ab is positioned away from at least one of the first hollow section S1 and the second hollow section S2, it is possible to avoid gas from both the first hollow section S1 and the second hollow section S2 being blown onto the exhaust valve 21ab. Furthermore, it is possible to suppress the opening of the exhaust valve 21ab before the internal pressure of the housing case 20 of the energy storage cell 100 mounted on the energy storage device 3 reaches a predetermined pressure.

[0072] In this embodiment, the cooler 13 of the energy storage device 3 is positioned opposite the opposing region 21ae. Furthermore, the exhaust valve 21ab is positioned to avoid the opposing region 21ae. The opening 7a is positioned opposite the exhaust valve 21ab. With this configuration, it is possible to avoid the opening 7a being blocked by the cooler 13. And it is possible to suppress the blocking of the outlet of the gas exhausted from the exhaust valve 21ab. Note that the exhaust valve 21ab only needs to be facing at least a part of the opening 7a.

[0073] Although an example has been shown in which the cooler 13 is positioned opposite the opposing region 21ae, the embodiments of this disclosure are not limited to this. For example, the cooler 13 may not face the opening 7a in the axial direction A, while the exhaust valve 21ab may face a part of the opening 7a in the axial direction A. With such a configuration, it is possible to avoid the opening 7a being blocked by the cooler 13. Furthermore, it is possible to suppress the blockage of the outlet of the gas exhausted from the exhaust valve 21ab.

[0074] In this embodiment, electrode terminals 22e are provided on the top plate body 22a, and an exhaust valve 21ab is formed on the bottom body 21aa. With this configuration, when gas is ejected from the exhaust valve 21ab, it is possible to suppress short circuits at the electrode terminals 22e caused by debris contained in the gas.

[0075] In this embodiment, the energy storage device 3 is located below the bottom 2a of the vehicle 1, and the top plate body 22a is located close to the bottom 2a relative to the bottom body 21aa. The exhaust valve 21ab is formed in the bottom body 21aa. With this configuration, it is possible to suppress the inflow of gas into the interior of the vehicle 1 when gas is ejected from the exhaust valve 21ab. <Example 1> In this embodiment, an example is shown in which the exhaust valve 21ab is positioned away from at least one of the first hollow portion S1 and the second hollow portion S2, but the embodiments of this disclosure are not limited thereto. For example, as shown in Figure 10, when the exhaust valve 21ab and the first winding end face 86 and the third winding end face 96 are viewed from a plan view from axial A, the exhaust valve 21ab may be positioned between the first hollow portion S1 and the second hollow portion S2. Furthermore, the exhaust valve 21ab may be positioned so as not to overlap either the first hollow portion S1 or the second hollow portion S2. Note that Figure 10 is a plan view of the outer surface of the bottom plate of the energy storage cell shown in Figure 8, viewed from a position away from the bottom plate towards the cooler side in the axial direction.

[0076] For example, if the exhaust valve 21ab is positioned away from at least one of the first hollow section S1 and the second hollow section S2, gas from at least one of the first hollow section S1 and the second hollow section S2 may blow onto the exhaust valve 21ab, causing it to open, and a portion of the electrode body 80 inside the housing case 20 may be discharged to the outside of the housing case 20 along with the gas forcefully expelled from the exhaust valve 21ab. For example, in the case of a first electrode body 81 which is a wound electrode body formed by winding a group of sheets, one end of the group of sheets forming the first electrode body 81 faces the first hollow section S1. Gas passing through the first hollow section S1 and ejected from the exhaust valve 21ab may unwind the first electrode body 81, and a portion of the first electrode body 81 may be discharged from the exhaust valve 21ab. If a portion of the electrode body 80 is exposed to the outside air, the compounds constituting the electrode body may react with the air and generate high temperatures. On the other hand, if the exhaust valve 21ab is positioned between the first hollow section S1 and the second hollow section S2, it is possible to avoid direct blowing of gas from the first hollow section S1 or the second hollow section S2 onto the exhaust valve 21ab. As a result, even if the exhaust valve 21ab ruptures, it is possible to suppress the discharge of a portion of the electrode body 80 to the outside as it is dragged along by the gas ejection. <Modification 2> In this embodiment, an example is shown in which the exhaust valve 21ab is positioned away from at least one of the first hollow portion S1 and the second hollow portion S2, but the embodiments of this disclosure are not limited thereto. For example, as shown in Figure 11, the exhaust valve 21ab may be positioned so as to overlap at least a portion with the gap region G. Figure 11 is a plan view of the outer surface of the bottom plate of the energy storage cell shown in Figure 8, viewed from a position away from the bottom plate towards the cooler in the axial direction.

[0077] By positioning the exhaust valve 21ab so that it overlaps with the gap area G, the area in which the exhaust valve 21ab overlaps with the electrode body 80 can be reduced. As a result, when the exhaust valve 21ab ruptures and gas inside the containment case 20 is ejected to the outside, the discharge of, for example, the first electrode sheet 82 forming the first electrode body 81 to the outside can be suppressed compared to when the exhaust valve 21ab is positioned to overlap with the electrode body 80. <Variation 3> In this embodiment, the electrode body 80 has a first electrode body 81 and a second electrode body 91, and an example is shown in which the first electrode body 81 and the second electrode body 91 are arranged adjacent to each other in the front-to-back direction D. However, the embodiments of this disclosure are not limited to this. For example, the energy storage cell may have three or more electrode bodies.

[0078] Using Figure 12, a modified example 3 of the energy storage cell 100, a energy storage cell 101 having three or more electrode bodies 80, will be described. Figure 12 is a plan view of modified example 3 of the energy storage cell in the embodiment of this disclosure, viewed from a position away from the bottom plate towards the cooler side in the axial direction.

[0079] The energy storage cell 101 has a plurality of electrode bodies 80, which include a first electrode body 81, a second electrode body 91, a third electrode body 111, and a fourth electrode body 112. The third electrode body 111 and the fourth electrode body 112 each have substantially the same configuration as the first electrode body 81. The third electrode body 111 is formed by winding an electrode body and a separator around a third winding axis α3 extending in the axial direction A. The third electrode body 111 has a third hollow portion S3 centered on the third winding axis α3. Similarly, the fourth electrode body 112 is formed by winding an electrode body and a separator around a fourth winding axis α4 extending in the axial direction A. The fourth electrode body 112 has a fourth hollow portion S4 centered on the fourth winding axis α4.

[0080] In a power storage cell 101 having such a configuration, the exhaust valve 21ab only needs to be positioned away from at least one of the first hollow section S1, the second hollow section S2, the third hollow section S3, and the fourth hollow section S4. <Modification 4> In the modified example 3 of the energy storage cell 101, the exhaust valve 21ab is positioned away from at least one of the first hollow section S1, the second hollow section S2, the third hollow section S3, and the fourth hollow section S4, but the disclosure is not limited thereto. As shown in Figure 13, the exhaust valve 21ab may be positioned away from all of the first hollow section S1, the second hollow section S2, the third hollow section S3, and the fourth hollow section S4.

[0081] While embodiments of this disclosure have been described above, the embodiments disclosed herein should be considered in all respects to be illustrative and not restrictive. The technical scope provided herein is defined by the claims and is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0082] 1 Vehicle, 2 Body, 2a Bottom, 3 Energy storage device, 4 Storage case, 5 Upper cover, 6 Lower case, 7 Bottom wall, 7a Opening, 8 Wall section, 9 Peripheral wall, 10 First side wall, 11 Second side wall, 12 Reinforcement section, 13 Cooler, 14 Share panel, 15 Energy storage stack, 20 Housing case, 21 Case body, 21a Bottom plate, 21aa Bottom body, 21ab Exhaust valve, 21ac Inner surface, 21ad Outer surface, 21ae Opposing area, 21af Outer edge, 21b Peripheral wall, 22 Top plate, 22a Top plate body, 22aa First connecting hole, 22ab Second connecting hole, 22ac Liquid injection hole, 22b Sealing plug, 22c Plug cover, 22d Insulating cover, 22e Electrode terminal, 30A First external terminal, 30B 40A Second external terminal, 40B First connecting member, 40A Second connecting member, 50A First seal ring, 50B Second seal ring, 60A First terminal support part, 60B Second terminal support part, 61A First locking ring, 61B Second locking ring, 62A First covering ring, 62B Second covering ring, 70 Insulating member, 71 Insulating bracket, 72 Peripheral insulating part, 73 Bottom insulating part, 80 Electrode body, 81 First electrode body, 82 First electrode sheet, 82A First current collector, 82B First active material layer, 83 Second electrode sheet, 83A Second current collector, 83B Second active material layer, 84A First separator, 84B Second separator, 85 Tape member, 86 First winding end face, 86a First arc part, 86b First straight part, 87 Second winding end face, 91 92 Second electrode body, 92A Third electrode sheet, 92A Third current collector, 92B Third active material layer, 93 Fourth electrode sheet, 93A Fourth current collector, 93B Fourth active material layer, 94A Third separator, 94B Fourth separator, 95 Tape member, 96 Third winding end face, 96a Second arc section, 96b Second straight section, 97 Fourth winding end face, 100 Energy storage cell, 101 Energy storage cell, 111 Third electrode body, 112 Fourth electrode body, 151A, 152A First tab, 151B, 152B Second tab, G Gap region, S1 First hollow section, S2 Second hollow section, S3 Third hollow section, S4 Fourth hollow section, V Storage space, α1 First winding axis, α2 Second winding axis, α3 Third winding axis, α4 Volume 4 rotation axis.

Claims

1. A first electrode body comprising a first electrode sheet, a first separator, a second electrode sheet, and a second separator, formed to surround a first winding axis extending in the axial direction, A second electrode body is arranged adjacent to the first electrode body and includes a third electrode sheet, a third separator, a fourth electrode sheet, and a fourth separator, and is formed to surround the periphery of a second winding axis extending in the axial direction. A housing case for housing the first electrode body and the second electrode body, Equipped with, The aforementioned housing case includes a first end plate and a second end plate on which an exhaust valve is formed, The first electrode body and the second electrode body are arranged such that the first winding axis and the second winding axis pass through the first end plate and the second end plate, The first electrode sheet intersects the axial direction and is located on the inner circumference side of the second electrode sheet in the first radial direction centered on the first winding axis, The third electrode sheet intersects the axial direction and is located on the inner circumference side of the fourth electrode sheet in the second radial direction centered on the second winding axis, The first electrode body includes a first wound end face located on the second end plate side and a second wound end face located on the first end plate side, and the first electrode body has a first hollow portion extending from the first wound end face to the second wound end face. The first hollow portion is defined by the first electrode sheet located on the innermost circumferential side in the first radial direction. The second electrode body includes a third wound end face located on the second end plate side and a fourth wound end face located on the first end plate side, and the second electrode body has a second hollow portion that extends from the third wound end face to the fourth wound end face. The second hollow portion is defined by the third electrode sheet located on the innermost circumferential side in the second radial direction. An energy storage device in which, when the exhaust valve, the first winding end face, and the third winding end face are viewed in plan from the axial direction, the exhaust valve is positioned away from at least one of the first hollow portion and the second hollow portion.

2. The energy storage device according to claim 1, wherein, when the exhaust valve, the first winding end face, and the third winding end face are viewed in plan from the axial direction, the exhaust valve is positioned between the first hollow portion and the second hollow portion.

3. The second end plate has an inner surface and an outer surface arranged in the axial direction, The outer surface is positioned away from the inner surface from the first electrode body and the second electrode body. The outer surface has an outer edge portion that defines the outer edge of the outer surface, A first circular arc portion is formed at the side end of the first winding end face. A second circular arc portion is formed at the side end of the third winding end face. When the outer surface, the first winding end surface, and the third winding end surface are viewed in plan in the axial direction, the outer edge, the first circular arc portion, and the second circular arc portion define a gap region on the outer surface. The energy storage device according to claim 1, wherein the exhaust valve is positioned so as to overlap at least a portion with the gap region.

4. Equipped with an additional cooler, The second end plate has an opening, The cooler does not face the opening in the axial direction. The energy storage device according to claim 1, wherein the exhaust valve faces at least a portion of the opening in the axial direction.

5. The second end plate has an inner surface and an outer surface arranged in the axial direction, and an opposing region defined within the outer surface. The outer surface is positioned away from the inner surface from the first electrode body and the second electrode body. The opposing region is the region where the outer surface and the first wound end face overlap when viewed in plan from the axial direction. The cooler is positioned in the axial direction opposite to the opposing region, The energy storage device according to claim 4, wherein the exhaust valve is arranged to avoid the opposing region.

6. The energy storage device according to claim 1, wherein the first end plate is provided with electrode terminals.

7. The aforementioned energy storage device is located below the bottom of the vehicle. The energy storage device according to claim 1, wherein the first end plate is positioned near the bottom of the second end plate.

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