Energy storage device

Abstract

To provide a power storage device capable of suppressing generation of stress at a corner portion connecting a portion along a power storage element and a portion along a terminating member in an extension member.SOLUTION: A power storage device includes a power storage element, a termination member aligned with the power storage element in a first direction, and an extension member 42 extending in the first direction along the power storage element and connected to the termination member, and the extension member includes at least a piece portion 421 which is a first portion extending in the first direction along the edge of the power storage element in the second direction perpendicular to the first direction, a connection piece portion 422 which is a second portion extending in the second direction along the termination member and connected to the termination member, a corner portion 423 connecting corresponding ends of the first portion and the second portion, and a reinforcing portion 425 that reinforces the corner at an end near the center of the terminating member in a third direction orthogonal to each of the first direction and the second direction at the corner.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a power storage device provided with a power storage element.

Background Art

[0002] Conventionally, a battery pack including a plurality of secondary battery cells has been known (see Patent Document 1). Specifically, as shown in FIG. 15, this battery pack 500 includes a plurality of secondary battery cells 501, a separator 502 interposed between main surfaces of the plurality of secondary battery cells 501 to stack the secondary battery cells 501 and insulating between the secondary battery cells 501, a pair of end plates 504 disposed on end faces in the stacking direction of a battery stack 503 in which the plurality of secondary battery cells 501 and the separator 502 are alternately stacked, and a plurality of metallic fastening members 505 disposed on the upper surface of the battery stack 503 and fastening the end plates 504 to each other.

[0003] Each secondary battery cell 501 has a rectangular shape in which an exterior can 501a constituting its outer shape is thinner in thickness than in width. This secondary battery cell 501 is made of a metallic exterior can 501a.

[0004] The separator 502 is a spacer for insulating and stacking adjacent secondary battery cells 501 electrically and thermally. This separator 502 is made of an insulating material such as plastic and is disposed between adjacent secondary battery cells 501 to insulate the adjacent secondary battery cells 501.

[0005] The pair of end plates 504 are disposed on both end faces of a battery stack 503 in which the secondary battery cells 501 and the separator 502 are alternately stacked to fasten the battery stack 503. This end plate 504 is made of, for example, metal.

[0006] The fastening member 505 is positioned on the upper side of the battery stack 503, which has end plates 504 stacked at both ends, and is fixed to the pair of end plates 504 to fasten the battery stack 503. This fastening member 505 has a main body portion 5051 that covers the upper surface of the battery stack 503, and bent pieces 5052 that are bent at both ends of the main body portion 5051 and fixed to the end plates 504. Such a fastening member 505 is made of a material with sufficient strength, such as metal.

[0007] In the above-described battery pack 500, the secondary battery cells 501 expand due to charging and discharging or deterioration over time, causing a large force to be applied to each end plate 504 in a direction that separates them from each other. At this time, stress tends to concentrate at the corners (bent portions) formed at both ends of the fastening members 505 connected to the pair of end plates 504, making these corners prone to damage. [Prior art documents] [Patent Documents]

[0008] [Patent Document 1] Patent No. 6328842 [Overview of the project] [Problems that the invention aims to solve]

[0009] Therefore, the objective of this embodiment is to provide an energy storage device in which the generation of stress at the corner of an extension member that extends along an energy storage element, and at the corner where the portion of the extension member along the energy storage element and the portion along the terminal member are connected, is suppressed. [Means for solving the problem]

[0010] The energy storage device of this embodiment is Energy storage element, In the first direction, a terminal member is arranged alongside the energy storage element, The system comprises an extending member that extends in the first direction along the energy storage element and is connected to the terminal member, The stretched member comprises at least, A first portion extending in the first direction along the end of the energy storage element in a second direction perpendicular to the first direction, A second portion extending in the second direction along the terminal member and connected to the terminal member, A corner connecting the corresponding ends of the first part and the second part, The device has a reinforcing portion that reinforces the corner at the end of the terminal member near the center in a third direction perpendicular to each of the first and second directions at the corner. [Effects of the Invention]

[0011] Based on the above, according to this embodiment, it is possible to provide an energy storage device that can suppress the generation of stress at the corner of an extension member that extends along an energy storage element, where the portion of the extension member along the energy storage element and the portion along the terminal member are connected. [Brief explanation of the drawing]

[0012] [Figure 1] Figure 1 is a perspective view of the energy storage device according to this embodiment. [Figure 2] Figure 2 is an exploded perspective view of the aforementioned energy storage device, with some components omitted. [Figure 3] Figure 3 is a perspective view of a pair of extendable members provided in the energy storage device. [Figure 4] Figure 4 is a view of the stretched member from the inside in the Y-axis direction. [Figure 5] Figure 5 is an enlarged perspective view of the first corner and surrounding portion of the stretched member. [Figure 6] Figure 6 is an enlarged perspective view of the first corner and its surrounding portion of the stretched member. [Figure 7] Figure 7 is an enlarged perspective view of the second corner and surrounding portion of the extension member. [Figure 8] Figure 8 is an enlarged perspective view of the second corner and surrounding portion of the stretched member. [Figure 9]FIG. 9 is an enlarged cross-sectional view of an end portion in the X-axis direction in the cross-section at the IX-IX position of FIG. 4. [Figure 10] FIG. 10 is an enlarged cross-sectional view of an end portion in the X-axis direction in the cross-section at the X-X position of FIG. 4. [Figure 11] FIG. 11 is a cross-sectional view at the XI-XI position of FIG. 4. [Figure 12] FIG. 12 is an enlarged cross-sectional view of an end portion in the X-axis direction in the cross-section at the XII-XII position of FIG. 4. [Figure 13] FIG. 13 is an enlarged perspective view of a first corner and its peripheral portion in an extension member according to another embodiment. [Figure 14] FIG. 14 is an enlarged cross-sectional view of a reinforcing portion of an extension member according to another embodiment. [Figure 15] FIG. 15 is a perspective view of a conventional assembled battery.

MODE FOR CARRYING OUT THE INVENTION

[0013] The power storage device of the present embodiment includes a power storage element, a terminal member aligned with the power storage element in a first direction, and an extension member that extends in the first direction along the power storage element and is connected to the terminal member. The extension member includes at least a first portion that extends in the first direction along an end portion of the power storage element in a second direction orthogonal to the first direction, a second portion that extends in the second direction along the terminal member and is connected to the terminal member, a corner that connects corresponding end portions of the first portion and the second portion, and a reinforcing portion that reinforces the corner at an end portion close to the center of the terminal member in a third direction orthogonal to each of the first direction and the second direction in the corner.

[0014] In this way, by providing reinforcing portions at least at the ends of corners where stress tends to concentrate (ends close to the center of the terminal member in the third direction), the rigidity of the corner is improved, thereby effectively suppressing the generation of stress at the corner.

[0015] In the aforementioned energy storage device, The reinforcing portion may extend from the end closest to the center of the terminal member at the corner in a direction away from the energy storage element and the terminal member.

[0016] This simple configuration makes it possible to improve the rigidity of the end portion of the extension member near the center of the terminal member and the surrounding portion at the corner of the extension member.

[0017] Furthermore, in the aforementioned energy storage device, The contour of the terminal member as viewed from the first direction is a rectangular shape that is elongated in the third direction. The extending members are arranged in pairs with a gap between them in the third direction, The first portion, the second portion, and the corner of each extension member may be positioned to correspond to the ends in the third direction of the long side that constitutes the rectangular contour when viewed from the first direction.

[0018] When the terminal member is constrained at both ends in the longitudinal direction (third direction) by the stretching member, and the energy storage element expands or otherwise causes the central part in the third direction to bulge, the stretching member deforms so that the second part connected to the terminal member twists relative to the first part. However, by providing a reinforcing part at the end in the third direction of the corner, where stress is likely to occur in this deformation, the rigidity of the end in the corner is improved, thereby effectively suppressing the generation of stress at the end in the corner.

[0019] Furthermore, in the aforementioned energy storage device, The second portion may have multiple connection points with the terminal member, spaced apart in the second direction.

[0020] With this configuration, the dimensions of the second part in the third direction can be kept small while firmly connecting the second part and the terminal member.

[0021] Hereinafter, one embodiment of the present invention will be described with reference to Figures 1 to 12. Note that the names of each component (each element) in this embodiment are those of this embodiment and may differ from the names of each component (each element) in the background art.

[0022] As shown in Figures 1 and 2, the energy storage device 1 comprises an energy storage element 10, a terminal member 41 aligned with the energy storage element 10 in a predetermined direction, and a holding member 4 having an extension member 42 that extends along the energy storage element 10 in the predetermined direction and is connected to the terminal member 41. The energy storage device 1 also comprises an adjacent member 2 adjacent to the energy storage element 10 in the predetermined direction.

[0023] More specifically, the energy storage device 1 comprises a plurality of energy storage elements 10 arranged in the predetermined direction, a plurality of adjacent members 2 adjacent to the energy storage elements 10 in the predetermined direction, and a holding member 4 that holds the plurality of energy storage elements 10 and the plurality of adjacent members 2. Furthermore, the energy storage device 1 of this embodiment comprises a first fastening member 5 that fixes at least one adjacent member 2 to the holding member 4, at least one insulator 6 disposed between the plurality of energy storage elements 10 and the holding member 4, and a plurality of busbars 8 that electrically connect different energy storage elements 10 to each other.

[0024] Each of the multiple energy storage elements 10 is a primary battery, a secondary battery, a capacitor, etc. The energy storage element 10 in this embodiment is a non-aqueous electrolyte secondary battery that can be charged and discharged. More specifically, the energy storage element 10 is a lithium-ion secondary battery that utilizes electron transfer that occurs with the movement of lithium ions.

[0025] Specifically, each energy storage element 10 comprises an electrode body, a case 11 that houses the electrode body together with an electrolyte, an external terminal 14 in which at least a portion is exposed to the outside of the case 11, and a current collector that connects the electrode body and the external terminal 14.

[0026] In the electrode body, positive and negative electrodes are stacked alternately with a separator in between. In this electrode body, lithium ions move between the positive and negative electrodes, causing the energy storage element 10 to charge and discharge.

[0027] Case 11 comprises a case body 12 having an opening and a plate-shaped lid 13 that closes (closes) the opening of the case body 12. The case body 12 has a rectangular tube shape with one end closed in the direction of the opening (i.e., a bottomed rectangular tube shape), and case 11 has a rectangular parallelepiped shape (hexagonal shape).

[0028] Specifically, the case body 12 comprises a plate-shaped closing portion 121 and a cylindrical body portion (peripheral wall) 122 connected to the periphery of the closing portion 121.

[0029] The closure portion 121 is located at the lower end of the case body 12 when the case body 12 is positioned with the opening facing upwards (i.e., it becomes the bottom wall of the case body 12 when the opening is facing upwards). The closure portion 121 is rectangular in shape when viewed from the direction normal to the closure portion 121.

[0030] The body portion 122 is rectangular in shape, more specifically, a flattened rectangular shape. The body portion 122 has a pair of long wall portions 123 extending from the long side at the periphery of the closure portion 121, and a pair of short wall portions 124 extending from the short side at the periphery of the closure portion 121. In this body portion 122, the short wall portions 124 connect the corresponding ends of the pair of long wall portions 123, thereby forming the rectangular body portion 122.

[0031] The cover plate 13 is a plate-shaped member that closes the opening of the case body 12. This cover plate 13 has a rectangular plate-shaped cover plate body 131 and a gas discharge valve 132 that is positioned on the cover plate body 131.

[0032] The gas discharge valve 132 discharges gas to the outside when the pressure inside the case 11 exceeds a predetermined value due to gas generation inside the case 11. In this embodiment, the gas discharge valve 132 is located in the center of the cover plate body 131 in the longitudinal direction.

[0033] The case 11 is formed when the cover plate 13, configured in this way, is joined to the case body 12 with its peripheral edge overlapping the opening peripheral edge of the case body 12.

[0034] In the above case 11, the shape is a flat rectangular parallelepiped, and the multiple energy storage elements 10 are arranged in the predetermined direction with the wide surfaces (long walls 123) of the case 11 facing each other. In this case, the gas discharge valves 132 of each energy storage element 10 are arranged in a line in the predetermined direction.

[0035] The external terminal 14 is a part that is electrically connected to the external terminal 14 of another energy storage element 10 or to external equipment, etc. The external terminal 14 is formed of a conductive material. For example, the external terminal 14 is formed of a highly weldable metal material such as aluminum or an aluminum alloy, or a copper alloy.

[0036] The energy storage element 10 of this embodiment is equipped with two external terminals 14, which are located at both ends of the cover plate 13 in the longitudinal direction. Specifically, the two external terminals 14 are positioned on the cover plate 13 with the gas discharge valve 132 in between.

[0037] In the following explanation, the direction in which multiple energy storage elements 10 are aligned (first direction) is defined as the X-axis of the Cartesian coordinate system, the direction in which the short wall portions 124 of the case 11 face each other (third direction) is defined as the Y-axis of the Cartesian coordinate system, and the direction in which the cover plate 13 and the closing portion 121 face each other (second direction) is defined as the Z-axis of the Cartesian coordinate system.

[0038] The adjacent member 2 is insulating and is positioned between energy storage elements 10 aligned in the X-axis direction, or between an energy storage element 10 and a member aligned with respect to the energy storage element 10 in the X-axis direction (in this embodiment, a part of the holding member 4). The adjacent member 2 in this embodiment is made of resin. This adjacent member 2 forms a flow path R through which a temperature-regulating fluid (in this embodiment, a gas such as air) can flow between adjacent energy storage elements 10. The energy storage device 1 in this embodiment comprises a plurality of adjacent members 2, and these plurality of adjacent members 2 include a plurality of adjacent members 2A, 2B, 2C.

[0039] Specifically, the plurality of adjacent members 2 include a first adjacent member 2A positioned between two adjacent energy storage elements 10, a second adjacent member 2B positioned between adjacent energy storage elements 10 and fixed to a holding member 4, and a third adjacent member 2C positioned between the holding member 4 and the energy storage element 10 at the outermost end in the X-axis direction, adjacent to the energy storage element 10. That is, the energy storage device 1 comprises a first adjacent member 2A, a second adjacent member 2B, and a third adjacent member 2C as adjacent members 2. The energy storage device 1 of this embodiment comprises a plurality of first adjacent members 2A, one second adjacent member 2B, and two (a pair) third adjacent members 2C. Each of these plurality of first adjacent members 2A is positioned between each energy storage element 10, excluding the positions between the energy storage elements 10 where the second adjacent member 2B is positioned.

[0040] Each of the multiple first adjacent members 2A has a first main body portion 21A that extends in a direction perpendicular to the X-axis direction between adjacent energy storage elements 10 in the X-axis direction, and at least one first restricting portion 25A that restricts the movement of the energy storage element 10 adjacent to the first main body portion 21A relative to the first main body portion 21A. In addition, each of the multiple first adjacent members 2A forms at least one flow path R through which a temperature-regulating fluid can flow between adjacent energy storage elements 10.

[0041] The first main body portion 21A is a part that faces the long wall portion 123 of the case 11 of the energy storage element 10, with a portion of it in contact with it. This first main body portion 21A, together with the adjacent energy storage element 10, forms a flow path R through which a temperature-regulating fluid can flow between it and the energy storage element 10. In this embodiment, the first main body portion 21A is a rectangular plate shape with a size corresponding to the energy storage element 10 when viewed from the X-axis direction, and its cross-sectional shape along the XZ plane (the plane including the X-axis direction and the Z-axis direction) is a rectangular wave shape.

[0042] The first restricting portion 25A extends in the X-axis direction from at least one corner of the rectangular first main body portion 21A and restricts the relative movement of the energy storage element 10 (specifically the case 11) adjacent to the first main body portion 21A in the YZ plane direction (a plane including the Y-axis direction and the Z-axis direction) by contacting the energy storage element 10 from the outside in the YZ plane direction. In this embodiment, the first restricting portion 25A extends from the first main body portion 21A toward one side and the other side in the X-axis direction.

[0043] The second adjacent member 2B has a second main body portion 21B that extends in a direction perpendicular to the X-axis direction (YZ plane direction) between two adjacent energy storage elements 10, and a second fastening member 22B used to fix the second adjacent member 2B to the holding member 4. The second adjacent member 2B also has at least one second restricting portion 25B that restricts the movement of the energy storage element 10 adjacent to the second main body portion 21B relative to the second main body portion 21B. The second adjacent member 2B also forms at least one flow path R through which a temperature-regulating fluid can flow between it and the adjacent energy storage elements 10.

[0044] The second main body portion 21B is a part that faces the long wall portion 123 of the case 11 of the energy storage element 10, with a portion of it in contact with it. This second main body portion 21B, together with the adjacent energy storage element 10, forms a flow path R through which a temperature-regulating fluid can flow between it and the energy storage element 10. The dimension of this second main body portion 21B in the X-axis direction is larger than the dimension of the first main body portion 21A in the X-axis direction (i.e., it is thicker). In this embodiment, the second main body portion 21B is a rectangular plate shape with a size corresponding to the energy storage element 10 when viewed from the X-axis direction. This second main body portion 21B has a plurality of protrusions 211B, each extending in the Y-axis direction and spaced apart in the Z-axis direction. These plurality of protrusions 211B protrude from the surface 212B of the second main body portion 21B that faces the energy storage element 10.

[0045] The second fastening members 22B are positioned at each end of the second main body 21B in the Y-axis direction. Each of these multiple second fastening members 22B fastens the second adjacent member 2B and the retaining member 4 by engaging with the first fastening member 5. In this embodiment, each second fastening member 22B is an insert nut. In this embodiment, each first fastening member 5 is a bolt, which fastens the second adjacent member 2B and the retaining member 4 by engaging (screwing) with the second fastening member 22B while the retaining member 4 is inserted through it.

[0046] The second restricting portion 25B extends in the X-axis direction from at least one corner of the rectangular second main body portion 21B and restricts the relative movement of the energy storage element 10 (specifically the case 11) adjacent to the second main body portion 21B in the YZ-axis direction by contacting it from the outside in the YZ-axis direction. In this embodiment, the second restricting portion 25B extends from the second main body portion 21B in one direction and the other in the X-axis direction.

[0047] Each of the two third adjacent members 2C has a third main body portion 21C that extends in a direction perpendicular to the X-axis direction between adjacent energy storage elements 10 in the X-axis direction and a portion of the holding member 4 (in this embodiment, the terminal member 41), and at least one third restricting portion 25C that restricts the movement of the energy storage element 10 adjacent to the third main body portion 21C relative to the third main body portion 21C. Furthermore, each of the two third adjacent members 2C forms at least one flow path R through which a temperature-regulating fluid can flow between adjacent energy storage elements 10.

[0048] The third main body portion 21C is a part that faces the long wall portion 123 of the energy storage element 10, with a portion of it in contact with it. Similar to the first main body portion 21A of the first adjacent member 2A and the second main body portion 21B of the second adjacent member 2B, this third main body portion 21C works together with the adjacent energy storage element 10 to form a flow path R through which a temperature-regulating fluid can flow between it and the energy storage element 10. In this embodiment, the third main body portion 21C is a rectangular plate shape with a size corresponding to the energy storage element 10 when viewed from the X-axis direction. This third main body portion 21C has a plurality of protrusions 211C, each extending in the Y-axis direction and spaced apart in the Z-axis direction. These plurality of protrusions 211C protrude from the surface 212C of the third main body portion 21C that faces the energy storage element 10.

[0049] The third restricting portion 25C extends in the X-axis direction from at least one corner of the rectangular third main body portion 21C and restricts the relative movement of the energy storage element 10 (specifically the case 11) adjacent to the third main body portion 21C in the YZ-axis direction by contacting it from the outside in the YZ-axis direction. In this embodiment, the third restricting portion 25C extends from the third main body portion 21C toward one side in the X-axis direction (towards the energy storage element 10).

[0050] The holding member 4 surrounds the multiple energy storage elements 10 and the multiple adjacent members 2, thereby holding these multiple energy storage elements 10 and multiple adjacent members 2 together. This holding member 4 is made of a conductive material such as metal.

[0051] Specifically, the holding member 4 includes a pair of end members 41 arranged on both sides of a plurality of energy storage elements 10 (a stack of energy storage elements 10) in the X-axis direction, and an extension member 42 extending along the X-axis direction at a position adjacent to the plurality of energy storage elements 10 in the Y-axis direction. The holding member 4 of this embodiment has a pair of extension members 42 arranged at intervals in the Y-axis direction, and each of the pair of extension members 42 connects the Y-axis ends of the pair of end members 41. The holding member 4 also has at least one fastening member 43 that fastens the end members 41 and the extension members 42. The holding member 4 of this embodiment has a plurality of fastening members 43.

[0052] Each of the pair of terminal members 41 is positioned to sandwich a third adjacent member 2C between itself and the energy storage element 10 located at its X-axis end (outermost end). Each of the pair of terminal members 41 is a rectangular plate shape with a size corresponding to the energy storage element 10 when viewed from the X-axis direction. Specifically, the contour of each terminal member 41 when viewed from the X-axis direction is a rectangle that is elongated in the Y-axis direction. Each terminal member 41 also has a plurality of through holes 411 at both ends in the Y-axis direction, spaced apart in the Z-axis direction.

[0053] Each extending member 42, as shown in Figures 3 to 12, has at least a piece (first portion) 421 extending in the X-axis direction along the end of the energy storage element 10 in the Z-axis direction, a connecting piece (second portion) 422 extending in the Z-axis direction along the end member 41 and connected to the end member 41, a corner portion 423 connecting the corresponding ends of the piece 421 and the connecting piece portion 422, and a reinforcing portion 425 reinforcing the corner portion 423. The extending member 42 in this embodiment is formed by drawing a plate member of a predetermined shape.

[0054] The extension member 42 of this embodiment has an extension member body 420 that extends in a direction perpendicular to the Y-axis direction at a position adjacent to each energy storage element 10 (more specifically, the short wall portion 124 of each energy storage element 10) in the Y-axis direction, and a pair of connecting pieces 422 that extend from each end of the extension member body 420 in the X-axis direction along the terminal member 41. In this extension member 42, the piece 421 includes a first piece 421A that extends from one end of the extension member body 420 in the Z-axis direction (upper in Figure 11) along the cover plate 13 of each energy storage element 10, and a second piece 421B that extends from the other end of the extension member body 420 in the Z-axis direction (lower in Figure 11) along the closing portion 121 of each energy storage element 10. Furthermore, the corner portion 423 includes a pair of first corner portions 423A (see Figures 3, 5, and 6) that connect the corresponding ends of the first piece portion 421A and the connecting piece portion 422, respectively, and a pair of second corner portions 423B (see Figures 3, 7, and 8) that connect the corresponding ends of the second piece portion 421B and the connecting piece portion 422, respectively. Furthermore, the reinforcing portion 425 includes a pair of first reinforcing portions 425A (see Figures 3, 5, and 6) that reinforce each first corner portion 423A, and a pair of second reinforcing portions 425B (see Figures 3, 7, and 8) that reinforce each second corner portion 423B.

[0055] The extension member body 420 is a plate-shaped portion that extends in a direction perpendicular to the Y-axis direction and has at least one through hole 4201. The extension member body 420 of this embodiment is rectangular in length in the X-axis direction when viewed from the Y-axis direction and has a plurality of through holes 4201. These plurality of through holes 4201 are arranged at intervals in the X-axis direction. Specifically, at least one through hole 4201 is a hole that is sized to correspond to a plurality of energy storage elements 10 and a plurality of first adjacent members 2A that are arranged alternately in the X-axis direction and penetrates in the Y-axis direction. When the energy storage device 1 is viewed from the Y-axis direction, the plurality of energy storage elements 10 and a plurality of first adjacent members 2A are exposed from this through hole 4201. In addition, the four corners of this extension member body 420 (the parts corresponding to the corner portions 423) are arc-shaped.

[0056] The first piece 421A extends from one end of the stretching member body 420 in the Z-axis direction in the Y-axis direction and also in the X-axis direction. This first piece 421A extends to a position in the Y-axis direction that does not come into contact with the external terminal 14 (i.e., a position in front of the external terminal 14). In this embodiment, the first piece 421A is a long, strip-shaped portion in the X-axis direction.

[0057] The second piece 421B extends in the Y-axis direction from the other end of the stretching member body 420 in the Z-axis direction, and also extends in the X-axis direction. In this embodiment, the second piece 421B is a long, strip-shaped portion in the X-axis direction. Furthermore, both ends of the second piece 421B in the X-axis direction have portions where the dimension (width) in the Y-axis direction decreases towards the end in the X-axis direction (see Figure 3). The dimension in the Y-axis direction of the central part of the second piece 421B in the X-axis direction is larger than the dimension in the Y-axis direction of the first piece 421A (see Figure 11), and is such that it does not come into contact with (abut against) the second piece 421B of the stretching member 42, which is positioned on the other side in the Y-axis direction with a laminate sandwiched between it and the stretching member 42 including the second piece 421B.

[0058] The connecting piece 422 extends in the Y-axis direction and the Z-axis direction along the terminal member 41 on the outer side of the terminal member 41 in the X-axis direction (opposite the side of the energy storage element 10). This connecting piece 422 has a connecting portion 4221 with the terminal member 41. In this embodiment, the connecting portion 4221 is a through hole provided at a position corresponding to the through hole 411 of the terminal member 41 (more specifically, a position that overlaps when viewed from the X-axis direction). Therefore, the connecting piece 422 has a plurality of connecting portions (through holes) 4221 arranged at intervals in the Z-axis direction.

[0059] Each of the pair of first corners 423A is a strip-shaped portion that connects the X-axis end of the first piece 421A to one Z-axis end of the connecting piece 422. In this embodiment, the first corners 423A extend in an arc shape when viewed from the Y-axis direction.

[0060] Each of the pair of second corner portions 423B is a strip-shaped portion that connects the X-axis end of the second piece portion 421B to the other Z-axis end of the connecting piece portion 422.

[0061] Each of the pair of first reinforcing portions 425A is positioned at the end of the first corner portion 423A closest to the center C (see Figure 1) in the Y-axis direction of the terminal member 41 (the end opposite to the side of the extension member body 420). Specifically, the first reinforcing portion 425A extends from the aforementioned end of the first corner portion 423A (i.e., the end of the first corner portion 423A on the center C side of the terminal member 41 in the Y-axis direction) in a direction away from the energy storage element 10 and the terminal member 41 (hereinafter also referred to as "outward") (see Figures 5 and 6). In this embodiment, the first reinforcing portion 425A is also positioned across the connecting piece portion 422 (more specifically, the end of the connecting piece portion 422 on the first corner portion 423A side). In other words, the first reinforcing portion 425A is the portion that extends outward from the end of the first corner portion 423A and the connecting piece portion 422 (more specifically, the end on the side of the first corner portion 423A) that is opposite to the side of the extending member body 420 in the Y-axis direction, so as to bend outward.

[0062] Each of the pair of second reinforcing portions 425B is positioned at the end of the second corner portion 423B closest to the center C in the Y-axis direction of the terminal member 41 (the end opposite to the extension member body 420). Specifically, the second reinforcing portion 425B extends from the aforementioned end of the second corner portion 423B (i.e., the end of the second corner portion 423B on the center C side of the terminal member 41 in the Y-axis direction) away from the energy storage element 10 and the terminal member 41 (outward) (see Figures 7 and 8). In this embodiment, the second reinforcing portion 425B also spans the connecting piece portion 422 (more specifically, the end of the connecting piece portion 422 on the second corner portion 423B side). In other words, the second reinforcing portion 425B is the portion that extends outward from the end of the second corner portion 423B and the connecting piece portion 422 (more specifically, the end on the second corner portion 423B side) that is opposite to the main body of the extending member 420 in the Y-axis direction, so as to bend outward.

[0063] Each of the multiple fastening members 43 fastens the end member 41 and the extension member 42 by inserting them through the through hole 411 of the end member 41 and the connecting portion 4221 of the extension member 42 (more specifically, the connecting piece 422). In this embodiment, each fastening member 43 is composed of a bolt 431 and a nut 432.

[0064] The insulator 6 has insulating properties. This insulator 6 is placed between the stretching member 42 and the plurality of energy storage elements 10. Specifically, the energy storage device 1 includes a pair of insulators 6, and each insulator 6 covers at least the region of the stretching member 42 that faces the plurality of energy storage elements 10. In this way, each insulator 6 insulates the stretching member 42 from the plurality of energy storage elements 10.

[0065] Specifically, the insulator 6 has an insulator body 60 having a shape corresponding to the stretchable member body 420. The insulator 6 of this embodiment has a first insulator piece 63 that extends in the Y-axis direction and the X-axis direction at a position corresponding to the first piece 421A in the Z-axis direction, and a second insulator piece 64 that extends in the Y-axis direction and the X-axis direction at a position corresponding to the second piece 421B in the Z-axis direction.

[0066] The insulator body 60 has through holes 61 at positions corresponding to each through hole 4201 of the stretching member body 420, with through holes 61 having the same size and shape as each through hole 4201 of the stretching member body 420. The insulator body 60 also has ribs 62 that protrude outward in the Y-axis direction (away from the laminate) from the periphery of the through holes 61, specifically protruding from the outer surface of the insulator body 60. The ribs 62 in this embodiment are annular ribs that protrude from the entire circumferential area of ​​the periphery of the through holes 61, and each rib protrudes from the periphery of each through hole 61.

[0067] The first insulator piece 63 is located between the first piece 421A and the laminate in the Z-axis direction, more specifically, between the first piece 421A and one of the regulating portions 25 (25A, 25B, 25C) in the Z-axis direction of each adjacent member 2 (2A, 2B, 2C). In this embodiment, the first insulator piece 63 extends in the Y-axis direction as if bent in the Y-axis direction from the insulator body 60.

[0068] The second insulator piece 64 is located between the second piece 421B and the laminate in the Z-axis direction, more specifically, between the second piece 421B and the other restricting portion 25 (25A, 25B, 25C) in the Z-axis direction of each adjacent member 2 (2A, 2B, 2C). In this embodiment, the second insulator piece 64 extends in the Y-axis direction as if bent in the Y-axis direction from the insulator body 60.

[0069] Furthermore, each insulator 6 in this embodiment does not have a portion corresponding to the connecting piece 422 of the stretching member 42 at each end in the X-axis direction.

[0070] Each of the multiple busbars 8 is a conductive plate-shaped member such as metal. Each busbar 8 connects the external terminals 14 of the energy storage elements 10 to each other. The multiple busbars 8 in this embodiment connect (connect) the multiple energy storage elements 10 included in the energy storage device 1 in series.

[0071] According to the above-described energy storage device 1, in the extension member 42 of the holding member 4, reinforcing portions 425 (first reinforcing portion 425A, second reinforcing portion 425B) are provided at least at the ends of the end member 41 in the Y-axis direction that are close to the center C in the Y-axis direction of the corner portion 423 (first corner portion 423A, second corner portion 423B) where stress tends to concentrate (i.e., the ends of the end member 41 on the center C side in the Y-axis direction), thereby improving the rigidity of the corner portion 423, and thereby effectively suppressing the generation of stress in the corner portion 423.

[0072] In the energy storage device 1 of this embodiment, the reinforcing portion 425 extends outward (away from the energy storage element 10 and the terminal member 41) from the end of the terminal member 41 near the center C at the corner portion 423. This simple configuration makes it possible to improve the rigidity of the end of the extending member 42 near the center C of the terminal member 41 at the corner portion 423 and the surrounding portion.

[0073] Furthermore, in the energy storage device 1 of this embodiment, the contour of the terminal member 41 as viewed from the X-axis direction is a long rectangle in the Y-axis direction, and the extension members 42 are arranged in pairs at intervals in the Y-axis direction. The pieces 421 (first piece 421A, second piece 421B), connecting piece 422, and corner 423 of each extension member 42 are positioned to correspond to the ends in the Y-axis direction of the long side that constitutes the rectangular contour of the terminal member 41 as viewed from the X-axis direction.

[0074] In this energy storage device 1, when the energy storage element 10 expands or otherwise bends so that the central part in the Y-axis direction bulges out, while the terminal member 41 is constrained at both ends in the longitudinal direction (Y-axis direction) by the stretching member 42, the stretching member 42 deforms so that the connecting piece 422 connected to the terminal member 41 twists relative to the piece 421. However, by providing a reinforcing portion 425 at the Y-axis end of the corner 423, where stress is likely to occur in this deformation, the rigidity of the end of the corner 423 is improved, thereby effectively suppressing the generation of stress at the end of the corner 423.

[0075] Furthermore, in the energy storage device 1 of this embodiment, the connecting piece 422 has multiple connection points 4221 with respect to the terminal member 41, spaced apart in the Z-axis direction. This allows for a strong connection between the connecting piece 422 and the terminal member 41 while keeping the dimensions of the connecting piece 422 in the Y-axis direction to a minimum.

[0076] It should be noted that the energy storage device of the present invention is not limited to the embodiments described above, and various modifications can be made without departing from the spirit of the invention. For example, the configuration of one embodiment can be added to the configuration of another embodiment, and a part of the configuration of one embodiment can be replaced with the configuration of another embodiment. Furthermore, a part of the configuration of one embodiment can be deleted.

[0077] The specific configuration of the reinforcing portion 425 in the extending member 42 is not limited. In the above embodiment, the reinforcing portion 425 extends outward (away from the energy storage element 10 and the terminal member 41) from the end of the terminal member 41 on the center C side at the corner 423, but it may also be composed of a protrusion or rib provided in a region including the end of the terminal member 41 on the center C side at the corner 423 (for example, the region indicated by reference numeral A in Figure 13). In the reinforcing portion 425 composed of this protrusion, the cross-sectional shape may be such that one surface is convex and the other surface (the back surface of one surface) is concave (see Figure 14(a)), or one surface is convex and the other surface is flat (see Figure 14(b)), or one surface is convex and the other surface is convex (see Figure 14(c)). The direction in which the protrusion or rib extends is not limited.

[0078] Furthermore, the reinforcing portion 425 may be configured such that the thickness dimension of the end of the terminal member 41 on the center C side at the corner 423 is larger than that of other parts of the corner 423. In other words, the reinforcing portion 425 should be configured to reinforce (increase the rigidity of) the end of the terminal member 41 on the center C side at the corner 423 more than that of other parts of the corner 423.

[0079] Furthermore, in the above embodiment, the extending member 42 has reinforcing portions 425 at each of the four corners 423, but the configuration is not limited to this. The reinforcing portions 425 only need to be located at least one corner 423. Also, the reinforcing portions 425 only need to be located at least one of the pair of extending members 42.

[0080] Furthermore, in the extension member 42 of the above embodiment, one reinforcing portion 425 is arranged for one corner portion 423, but the configuration is not limited to this. Multiple reinforcing portions 425 may be arranged for one corner portion 423 (see the area indicated by reference numeral A in Figure 13).

[0081] Furthermore, although the extending member 42 in the above embodiment has an extending member body 420, it is not limited to this configuration. The extending member 42 may also have a configuration without an extending member body 420, that is, a configuration having a single piece 421, a connecting piece 422, a corner piece 423, and a reinforcing piece 425.

[0082] Furthermore, while the above embodiments described a case where the energy storage element is used as a non-aqueous electrolyte secondary battery (e.g., a lithium-ion secondary battery) capable of charging and discharging, the type and size (capacity) of the energy storage element are arbitrary. Also, while the above embodiments described a lithium-ion secondary battery as an example of an energy storage element, the invention is not limited to this. For example, the present invention can be applied to various secondary batteries, as well as primary batteries and capacitors such as electric double-layer capacitors. [Explanation of symbols]

[0083] 1...Energy storage device, 2...Adjacent member, 2A...First adjacent member, 21A...First main body, 25A...First restricting part, 2B...Second adjacent member, 21B...Second main body, 211B...Protrusion, 212B...Opposite surface, 22B...Second fastening member, 25B...Second restricting part, 2C...Third adjacent member, 21C...Third main body, 211C...Protrusion, 212C...Opposite surface, 25C...Third restricting part, 4...Retainer Member, 41...End member, 411...Through hole, 42...Extended member, 420...Extended member body, 4201...Through hole, 421...Single piece (first part), 421A...First piece, 421B...Second piece, 422...Connecting piece (second part), 4221...Connecting part (through hole), 423...Corner, 423A...First corner, 423B...Second corner, 425...Reinforcement part, 425A...First reinforcement part, 4 25B...Second reinforcement part, 43...Fastening member, 431...Bolt, 432...Nut, 5...First fastening member, 6...Insulator, 60...Insulator body, 61...Through hole, 62...Rib, 63...First insulator piece, 64...Second insulator piece, 8...Bus bar, 10...Energy storage element, 11...Case, 12...Case body, 121...Closing part, 122...Body part, 123...Long wall part, 124...Short wall part, 13...Lid plate, 131...Lid plate body, 132...Gas discharge valve, 14...External terminal, 500...Battery pack, 501...Secondary battery cell, 501a...Outer can, 502...Separator, 503...Battery stack, 504...End plate, 505...Fastening member, 5051...Body part, 5052...Bent piece, A...Region, C...Center of the terminal member in the Y-axis direction, R...Flow path

Claims

1. Energy storage element, In the first direction, a terminal member is arranged alongside the energy storage element, The system comprises an extending member that extends in the first direction along the energy storage element and is connected to the terminal member, The stretched member comprises at least, A first portion extending in the first direction along the end of the energy storage element in a second direction perpendicular to the first direction, A second portion extending in the second direction along the terminal member and connected to the terminal member, A corner connecting the corresponding ends of the first part and the second part, A power storage device having a reinforcing portion that reinforces the corner at the end of the terminal member near the center in a third direction perpendicular to each of the first and second directions at the corner.

2. The energy storage device according to claim 1, wherein the reinforcing portion extends from the end of the terminal member near the center at the corner in a direction away from the energy storage element and the terminal member.

3. The contour of the terminal member as viewed from the first direction is a rectangular shape that is elongated in the third direction. The extending members are arranged in pairs with a gap between them in the third direction, The energy storage device according to claim 1 or 2, wherein the first portion, the second portion, and the corner of each extension member are positioned to correspond to the ends in the third direction of the long side that constitutes the rectangular contour when viewed from the first direction.

4. The energy storage device according to any one of claims 1 to 3, wherein the second portion has a plurality of connection portions with the terminal member spaced apart in the second direction.

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