power storage device

Abstract

The power storage device includes a power storage module, a pair of current collecting plates stacked in a first direction so as to sandwich the power storage module, and a pair of constraint plates that constrain the power storage module and the current collecting plates in the first direction, wherein the power storage module has current extraction surfaces at both ends in the first direction, at least one of the current collecting plates has a flat plate portion that electrically contacts the current extraction surfaces and an extraction portion that extracts current from the power storage module, the extraction portion has a first piece portion that extends in a direction orthogonal to the first direction from an outer edge portion provided from an edge of the flat plate portion when viewed in the first direction, a second piece portion that extends in the first direction and has a fitting portion that fits the extraction portion to a terminal seat of the constraint plate, and a bent portion that is bent from a sheet material that constitutes the extraction portion and connects the first piece portion and the second piece portion, a spring portion that relieves stress acting on the extraction portion is present between a connection portion of the extraction portion to the outer edge portion and the fitting portion, and the spring portion has at least a first bent portion that is bent from the sheet material other than the bent portion.

Description

Technical Field

[0001] This disclosure relates to energy storage devices. Background Technology

[0002] As existing energy storage devices, energy storage devices comprising multiple stacked energy storage modules are known. Furthermore, as existing energy storage modules, bipolar batteries comprising bipolar electrodes with a positive electrode formed on one side of an electrode plate and a negative electrode formed on the other side of the electrode plate are known. Multiple energy storage modules are stacked and constrained from both ends in the stacking direction by constraint plates. Current collectors with flat plates are provided for the energy storage modules at the ends in the stacking direction (Japanese Patent Application Laid-Open No. 2007-213990). Summary of the Invention

[0003] In such an energy storage device, the current collector has a extraction section that extracts current from the energy storage module. This extraction section is susceptible to defects such as breakage due to vibration acting on the energy storage device.

[0004] The present invention was made to solve the above-mentioned problems and provides an energy storage device that can suppress the breakage of the current collector plate extraction part when vibrating.

[0005] The energy storage device disclosed herein includes: an energy storage module; a pair of current collectors stacked in a first direction to sandwich the energy storage module; and a pair of constraint plates constraining the energy storage module and the current collectors in the first direction. In the energy storage device, the energy storage module has current extraction surfaces at both ends in the first direction. At least one current collector has: a flat plate portion that is electrically in contact with the current extraction surface; and an extraction portion connected to the flat plate portion for extracting current from the energy storage module. The extraction portion has: a first piece portion that extends from an outer edge portion provided at the edge of the flat plate portion in a direction orthogonal to the first direction when viewed from the first direction; a second piece portion that extends in the first direction and has an assembly portion for assembling the extraction portion to a terminal seat of the constraint plates; and a bending portion formed by bending a sheet material constituting the extraction portion, connecting the first piece portion and the second piece portion. Between the connection portion of the extraction portion and the outer edge portion to the assembly portion, there is a spring portion for relieving stress acting on the extraction portion. The spring portion has at least a first bending portion formed by bending the sheet material outside the bending portion.

[0006] In this energy storage device, at least one current collector plate has a take-out portion for extracting current from the energy storage module. Therefore, the take-out portion can extract current to the terminal block by connecting to the terminal block. Here, the take-out portion has: a first piece extending from an outer edge of a flat plate portion orthogonal to the first direction when viewed from the first direction; a second piece extending in the first direction, having an assembly portion for fixing the take-out portion to the terminal block; and a bent portion formed by bending the sheet metal constituting the take-out portion, connecting the first piece and the second piece. In this configuration, the bent portion between the first and second pieces functions as one of the starting points for deformation during assembly to the terminal block. Furthermore, the distance between the bent portion and the assembly position to the terminal block is short. Therefore, when the second piece is assembled via the assembly portion, the stress near the assembly position may increase. In the event of vibration under these conditions, the take-out portion may break. To address this, a spring portion is provided between the connection portion of the take-out section and the assembly portion to alleviate the stress acting on the take-out section. The spring portion has at least a first bend formed by bending the sheet metal outside the bend portion. By forming this spring portion between the connection portion and the assembly portion of the take-out section, the stress concentrated near the assembly position of the take-out section can be alleviated. Based on the above, breakage of the take-out section of the current collector plate during vibration can be suppressed.

[0007] Alternatively, the spring portion may also have a second bend, which is formed by bending the sheet metal to the side opposite to the first bend when viewed from the connecting portion. In this case, although the sheet metal of the first piece is positioned differently from the reference shape by the first bend, it can return to its original reference shape by the second bend. Thus, the shape of the extraction portion is maintained in a state where it does not change excessively from the reference shape.

[0008] Alternatively, the spring portion can be formed in the first piece. Since the first piece extends in a direction orthogonal to the first direction, when a vibration in the first direction acts on the energy storage device, the first piece will deform by alternately flexing to one side and the other side in the first direction. Here, the spring portion can function as a node for this flexure, thus reducing the deformation caused by the vibration of the first piece.

[0009] Alternatively, the bent portion can be positioned on the side opposite to the terminal block in the first direction, more so than the connecting portion. In this case, the distance between the assembly position of the second piece and the terminal block and the bent portion can be increased. As mentioned earlier, the bent portion functions as one of the starting points for deformation during assembly to the terminal block. Therefore, by increasing the distance between the assembly position and the bent portion, the amount of deformation increases, thus alleviating the stress concentrated around the assembly portion.

[0010] According to this disclosure, an energy storage device can be provided that can suppress defects in the extraction portion of the current collector plate when vibration occurs. Attached Figure Description

[0011] Figure 1 This is a perspective view of an energy storage device according to one implementation method.

[0012] Figure 2 It is a three-dimensional view of the structure near the negative end in the Z-axis direction of the energy storage device.

[0013] Figure 3 This is a three-dimensional diagram of the connection structure between the positive terminal and the terminal block.

[0014] Figure 4 This is a cross-sectional view of the connection structure between the positive terminal and the terminal block.

[0015] Figure 5 This diagram shows the deformation of the positive terminal when it is assembled into the terminal block.

[0016] Figure 6 This is a diagram showing the deformation of the positive terminal when it vibrates.

[0017] Figure 7 of (a), Figure 7 (b) is a diagram showing the positive terminal of the energy storage device of the comparative example.

[0018] Figure 8 of (a), Figure 8 (b) is a diagram showing the positive terminal of a modified energy storage device.

[0019] Explanation of reference numerals in the attached figures

[0020] 1…Energy storage device; 3…Energy storage module; 5A, 5B…Current collector; 6, 206, 306…Positive terminal (removal part); 7…Negative terminal (removal part); 8A, 8B…Constraint plate; 15…Plate part; 17…Terminal base; 41, 241, 341…First piece; 42, 242, 342…Second piece; 43…Through hole (assembly part); 46…Connecting part; 47, 247, 347…Bending part; 50…Spring part; 51…Bending part (first bending part); 52, 252…Bending part (second bending part). Detailed Implementation

[0021] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the description of the drawings, the same reference numerals are used for the same or equivalent elements, and repeated descriptions are omitted.

[0022] Reference Figure 1 The energy storage device 1 of this embodiment is described. Figure 1 This is a side view of the energy storage device 1.

[0023] The energy storage device 1 is used, for example, as a battery for various vehicles such as forklifts, hybrid vehicles, and electric vehicles. The energy storage device 1 includes a modular stack 2 and a constraint member 4. The modular stack 2 contains a plurality of stacked energy storage modules 3. The constraint member 4 applies constraint loads to the modular stack 2 from both sides in the stacking direction (first direction). When viewed from the stacking direction, the energy storage module 3 has, for example, a rectangular shape. In this specification, for ease of explanation, the stacking direction is defined as the Z-axis direction, the long side direction of the energy storage module 3 when viewed from the stacking direction is defined as the Y-axis direction, and the short side direction of the energy storage module 3 is defined as the X-axis direction. Furthermore, the stacking direction refers to the direction in which the energy storage module 3 is stacked with a pair of current collectors 5A and 5B (described later).

[0024] The module stack 2 includes multiple (seven in this embodiment) energy storage modules 3 and multiple (eight in this embodiment) current collectors 5. As an example, the energy storage module 3 is a bipolar battery. The energy storage module 3 is, for example, a nickel-metal hydride secondary battery or a lithium-ion secondary battery. However, the energy storage device 1 is not limited to the above-mentioned secondary batteries; for example, it can also be a double-layer capacitor. In this embodiment, the energy storage device 1 is a nickel-metal hydride secondary battery.

[0025] Multiple energy storage modules 3 are stacked with a current collector 5 between them. Adjacent energy storage modules 3 in the Z-axis direction are electrically connected to each other via the current collector 5. In this embodiment, as... Figure 1 As shown, the multiple (eight) current collectors 5 consist of a current collector 5A on one end in the Z-axis direction, a current collector 5B on the other end, and multiple (six) current collectors 5C located between the energy storage modules 3. The current collectors 5C are disposed between adjacent energy storage modules 3 in the Z-axis direction. Between adjacent energy storage modules 3 in the Z-axis direction, the current collectors 5C are arranged in contact between the exposed electrode portions of opposing electrode stacks.

[0026] Current collectors 5A and 5B are disposed on the positive and negative sides of the energy storage modules 3 located at the stacking end of the plurality of energy storage modules 3, respectively, along the Z-axis. Thus, current collectors 5A and 5B are stacked in a manner that sandwiches the energy storage modules 3 along the Z-axis, which is the stacking direction. Figure 1 As shown, a negative terminal 7 (removal portion) is connected to one current collector plate 5A. A positive terminal 6 (removal portion) is connected to another current collector plate 5B. The negative terminal 7 and the positive terminal 6 protrude from the edges of the current collector plates 5A and 5B in the Y-axis direction. Charging and discharging of the energy storage device 1 are performed via the negative terminal 7 and the positive terminal 6. Furthermore, the negative terminal 7 and the positive terminal 6 are located at the negative end of the energy storage device 1 in the Y-axis direction. In this embodiment, the negative terminal 7 is located biased towards the positive side in the X-axis direction, and the positive terminal 6 is located biased towards the negative side in the X-axis direction.

[0027] The constraint member 4 includes: a pair of constraint plates 8 (constraint plate 8A on the negative terminal 7 side and constraint plate 8B on the positive terminal 6 side) sandwiching the module stack 2 from both sides in the Z-axis direction, and a plurality of connecting members 9 connecting the pair of constraint plates 8. The pair of constraint plates 8 constrain the energy storage module 3 and the current collectors 5A and 5B in the Z-axis direction, which is the stacking direction. The connecting members 9 apply constraint loads to the module stack 2 in the Z-axis direction via the pair of constraint plates 8. In this embodiment, the connecting members 9 are composed of bolts 9a and nuts 9b that fasten the pair of constraint plates 8.

[0028] The constraint plate 8 is a rectangular metal plate with an area one size larger than that of the energy storage module 3 and the current collector plate 5 when viewed from the Z-axis direction. The constraint plate 8 has: a main body 11 that overlaps with the module stack 2 when viewed from the Z-axis direction; and an edge portion 10 that extends from the main body 11 in the X-axis direction and does not overlap with the module stack 2 when viewed from the Z-axis direction. In this embodiment, a pair of edge portions 10 are provided on both sides of the main body 11 in the X-axis direction. That is, the main body 11 is sandwiched between a pair of edge portions 10. The edge portion 10 has: an outer surface 10a facing outward in the Z-axis direction (the side opposite to the energy storage module 3 in the Z-axis direction); and an inner surface 10b facing inward in the Z-axis direction (the side of the energy storage module 3 in the Z-axis direction). The main body 11 has an outer surface 11a facing outward in the Z-axis direction and an inner surface 11b facing inward in the Z-axis direction. The outer surface 10a is located further inward in the Z-axis direction than the outer surface 11a. The inner surface 10b is located inside the inner surface 11b in the Z-axis direction.

[0029] A pair of edge portions 10 are the outer edges extending along the long side direction (Y-axis direction) of the constraint plate 8. The pair of edge portions 10 are configured not to overlap with the module stack 2 when viewed from the Z-axis direction. Each edge portion 10 is provided with a plurality of through holes 10c for inserting bolts 9a. In each edge portion 10, the plurality of through holes 10c are configured to be separated from each other along the long side direction (Y-axis direction) of the constraint plate 8. In this embodiment, the plurality of through holes 10c are arranged at equal intervals from one end to the other of the edge portion 10 along the long side direction of the constraint plate 8.

[0030] The head of bolt 9a is positioned on the outer surface 10a of constraint plate 8A. The top end (screw head) of the shaft portion of bolt 9a protrudes from the outer surface 10a of constraint plate 8B. A nut 9b is screwed onto the top end of bolt 9a. Nut 9b is positioned on the outer surface 10a of constraint plate 8B. Thus, multiple energy storage modules 3 and multiple current collectors 5 are clamped by constraint plates 8A and 8B and modularized as a module stack 2. In addition, a constraint load in the Z-axis direction is applied to the module stack 2.

[0031] An insulating plate 20A is provided between the current collector plate 5A and the constraint plate 8A. Additionally, an insulating plate 20B is provided between the current collector plate 5B and the constraint plate 8B. The insulating plates 20A and 20B are components used to ensure insulation between the current collector plates 5A and 5B and the constraint plates 8A and 8B.

[0032] Next, refer to Figure 2 The configuration near the end in the Z-axis direction of the energy storage device 1 will be described in more detail. Figure 2 This is an unfolded perspective view of the structure near the negative end in the Z-axis direction of the energy storage device 1. Furthermore, in Figure 2 In this section, the configuration near the end corresponding to the negative side (positive end 6 side) in the Z-axis direction will be described, but the configuration near the end corresponding to the positive side (negative end 7 side) in the Z-axis direction also has the same basic principle.

[0033] like Figure 2 As shown, the energy storage device 1 has an energy storage module 3, a current collector plate 5B, an insulating plate 20B, and a constraint plate 8B near the negative end in the Z-axis direction. The energy storage module 3, the current collector plate 5B, the insulating plate 20B, and the constraint plate 8B have a rectangular plate shape with the Y-axis direction as the long side.

[0034] The energy storage module 3 is composed of a laminate 13, which is constructed by stacking multiple separators and bipolar electrodes, one side of which has a positive electrode and the other side has a negative electrode, on the laminate. Furthermore, a frame-shaped sealing member 14 (frame) is provided on the side of the laminate 13, thereby sealing the laminate 13. An electrolyte, which is a liquid, is sealed inside the laminate 13. In addition, the energy storage module 3 has current extraction surfaces 13a at both ends in the Z-axis direction. The current extraction surfaces 13a are surfaces from which current is extracted from the energy storage module 3, and are formed by exposing the electrodes of the laminate 13 from the sealing member 14.

[0035] The current collector 5B has a flat plate portion 15 disposed relative to the energy storage module 3 and the aforementioned positive terminal 6. The flat plate portion 15 contacts the current extraction surface 13a of the energy storage module 3. The flat plate portion 15 is formed such that its entire area overlaps with the current extraction surface 13a when viewed from the Z-axis direction. The positive terminal 6 is formed on the outer edge portion 15a of the flat plate portion 15 on the negative side in the Y-axis direction. Thus, a pair of current collectors 5A (refer to...) Figure 1 The current collector 5A and the current collector 5B are arranged such that they sandwich the current extraction surfaces 13a on both ends in the stacking direction. Furthermore, in this embodiment, multiple energy storage modules 3 are stacked. Therefore, the current collector 5A (refer to...) Figure 1The current extraction surface 13a of the energy storage module 3 on the positive side of the Z-axis direction is in contact with the current extraction surface 13a of the energy storage module 3 on the negative side of the Z-axis direction, and the current extraction surface 5B of the current storage module 3 on the negative side of the Z-axis direction is in contact with the current extraction surface 13a of the energy storage module 3 on the negative side of the Z-axis direction. However, the energy storage device 1 may also have a single energy storage module 3. In this case, the current extraction surfaces 5A and 5B are arranged such that they sandwich the current extraction surfaces 13a on both sides of the energy storage module 3.

[0036] The insulating plate 20B is a component made of an insulating material such as resin, disposed between the current collector plate 5B and the constraint plate 8B. The insulating plate 20B is provided to ensure insulation between the current collector plate 5B and the constraint plate 8B. The insulating plate 20B is configured to overlap the entire area of ​​the flat plate portion 15 of the current collector plate 5B when viewed from the Z-axis direction. Thus, the insulating plate 20B is positioned between the current collector plate 5B and the constraint plate 8B, ensuring insulation between them. Furthermore, a terminal block protection portion 16 is formed on the cover portion 24 on the negative side of the Y-axis direction of the insulating plate 20B, covering the terminal block 17 (described later). A more detailed description of the configuration of the insulating plate 20B will follow.

[0037] As described above, the constraint plate 8B has a flat body portion 11 and a pair of edge portions 10 with through holes 10c for bolt insertion. A terminal block 17 is provided on the outer edge portion 8a on the negative side of the constraint plate 8B in the Y-axis direction. The positive terminal 6 and wiring (not shown) are connected to this terminal block 17.

[0038] Next, refer to Figure 3 and Figure 4 The connection structure between the positive terminal 6 and the terminal block 17 is described in detail. Figure 3 This is a perspective view of the connection structure between the positive terminal 6 and the terminal block 17. Figure 4 This is a cross-sectional view of the connection structure between the positive terminal 6 and the terminal block 17. Furthermore, from... Figure 3 The energy storage module 3 is omitted. Furthermore, in the following description, considering the relationship with the flow of liquid leaking from the energy storage module 3, the description will be based on the orientation of the current collector plate 5B being positioned lower than the energy storage module 3 in the vertical direction. That is, the liquid flows from the positive side to the negative side in the Z-axis direction. In the following description, the positive side in the Z-axis direction will sometimes be referred to as "upper," and the negative side in the Z-axis direction as "lower." In addition, a constraint plate 8A, a current collector plate 5A, and an insulating plate 20A are also provided on the positive side in the Z-axis direction, and these constraint plate 8A, current collector plate 5A, and insulating plate 20A are also related to… Figure 3 The constraint plate 8B, current collector plate 5B, and insulating plate 20B on the negative side of the Z-axis direction, as shown, are symmetrically arranged and share the same purpose. Therefore, when the positive side of the Z-axis direction faces downward, the liquid leaking from the energy storage module 3 flows from the negative side to the positive side of the Z-axis direction, and the insulating plate 20A on the constraint plate 8A side receives this liquid.

[0039] like Figure 3 and Figure 4 As shown, the terminal block 17 includes a base portion 31 and a fastening portion 32. The base portion 31 has a cuboid shape with its long side in the X-axis direction. The base portion 31 is positioned such that it extends from the outer edge 8a of the constraint plate 8B (see reference). Figure 4 The base portion 31 protrudes to the negative side in the Y-axis direction. It protrudes at least to a position on the negative side of the Y-axis direction relative to the energy storage module 3. The vertical dimension of the base portion 31 is approximately the same as the vertical dimension of the outer edge portion 8a. The base portion 31 is configured to extend in the X-axis direction within a portion of the region on the negative side of the outer edge portion 8a of the main body portion 11 of the constraint plate 8B.

[0040] The fastening part 32 is constituted by a bolt protruding from the end face of the base part 31 in the negative Y-axis direction. The fastening part 32 extends parallel to the Y-axis direction toward the negative Y-axis direction. Furthermore, the fastening part 32 is supported by a cylindrical support metal member 33 (see reference) disposed inside the base part 31. Figure 4 Furthermore, the supporting metal member 33 has a flange portion 33a extending from the fastening portion 32 toward the outer periphery at the end face of the base portion 31 in the negative Y-axis direction (see reference). Figure 4 The second piece 42 of the positive terminal 6, described later, and the washer 37 connected to the wiring 36 are assembled to the fastening part 32 by being pressed by the nut 38 fastened to the fastening part 32 (see reference). Figure 3 ).

[0041] like Figure 3 As shown, the insulating plate 20B has a main body portion 21 and a cover portion 24. The main body portion 21 is a flat plate portion disposed between the flat plate portion 15 of the current collector plate 5B and the main body portion 11 of the constraint plate 8. The main body portion 21 has a rectangular shape with its long side in the Y-axis direction. The cover portion 24 extends downward from the outer edge portion 21a on the negative side of the Y-axis direction of the main body portion 21. The cover portion 24 extends in the X-axis direction along the outer edge portion 21a. The terminal block protection portion 16 is provided to protrude from the cover portion 24 in the negative Y-axis direction. The terminal block protection portion 16 has a box-shaped shape that internally houses the terminal block 17.

[0042] The terminal block protection portion 16 includes: an upper wall portion 22 extending from the main body portion 21 toward the negative side in the Y-axis direction; a pair of side wall portions 23, 23 extending from the cover portion 24 toward the negative side in the Y-axis direction; and an end wall portion 26 extending parallel to the cover portion 24 at the ends of the upper wall portion 22 and the side wall portions 23, 23 on the negative side in the Y-axis direction. The upper wall portion 22 is configured to cover the base portion 31 of the terminal block 17 from above. The side wall portions 23, 23 are configured to cover the terminal block 17 from both sides in the X-axis direction. The end wall portion 26 is positioned in the Y-axis direction at approximately the same position as the end of the base portion 31 of the terminal block 17 on the negative side in the Y-axis direction. The end wall portion 26 has an opening at the location of the terminal block 17, thereby exposing the terminal block 17.

[0043] A recess 27 is formed in the upper wall portion 22 of the terminal block protection portion 16, which is recessed downwards compared to other areas. The recess 27 has the function of receiving and storing liquid in the event of leakage from the energy storage module 3. The recess 27 has a bottom surface 27a, long sides 27b and 27c, and short sides 27d and 27e. The bottom surface 27a extends parallel to the XY plane at a position lower than other areas of the upper wall portion 22. The long side portion 27b extends parallel to the X-axis direction near the end of the upper wall portion 22 on the negative side of the Y-axis direction. The long side portion 27b is located at a position separated from the end wall portion 26 on the positive side of the Y-axis direction. The long side portion 27b extends parallel to the X-axis direction in the Y-axis direction at a position corresponding to the outer edge portion 21a of the main body portion 21. The short sides 27d and 27e extend parallel to the Y-axis direction in the X-axis direction at positions separated from the two ends of the terminal block 17 on the outwards, respectively. Furthermore, a recess 27 is also formed in the main body 21 at the portion through which the positive terminal 6 passes. The recess 27 extends to a stepped portion 21b located on the positive side of the flat plate portion 15 in the Y-axis direction (see reference). Figure 4 At both ends of the long side portion 27b of the recess 27 in the X-axis direction, grooves 28, 28 extending to the end wall portion 26 are formed. The grooves 28, 28 can discharge the liquid stored in the recess 27 to the end wall portion 26 at a position avoiding the terminal seat 17.

[0044] Next, the structure of the positive terminal 6 will be explained in detail. For example... Figure 3As shown, the positive terminal 6 is configured in a roughly L-shape when viewed from the X-axis direction by having a first plate portion 41, a second plate portion 42, and a bent portion 47. The first plate portion 41 is a plate-shaped portion that extends from the outer edge portion 15a provided at the edge of the flat plate portion 15 in a direction orthogonal to the stacking direction (in this case, the Y-axis direction) when viewed from the stacking direction (in this case, the Z-axis direction). Furthermore, the state in which the first plate portion 41 extends in a direction orthogonal to the stacking direction includes not only a state that is exactly 90° relative to the stacking direction, but also a state that is slightly tilted relative to the stacking direction due to manufacturing errors, etc. The first plate portion 41 is a plate-shaped portion that extends from the outer edge portion 15a of the flat plate portion 15 in a direction extending from the flat plate portion 15 (in this case, the Y-axis direction). The second plate portion 42 is a portion that extends in the Z-axis direction and has a through hole 43 (mounting portion) for mounting the positive terminal 6 to the terminal block 17. Furthermore, the structure of the assembly part is not limited to the through hole 43, and can be appropriately modified according to the assembly structure with the terminal block 17. The second piece 42 is a plate-shaped part that is folded from the top of the first piece 41 toward the terminal block 17 side (lower side) along the stacking direction and assembled in a state of being pressed against the terminal block 17. A through hole 43 extending in the Y-axis direction is formed at approximately the center position of the second piece 42. The fastening part 32 is inserted into the through hole 43. Both the first piece 41 and the second piece 42 extend parallel to each other in the X-axis direction, and the size of their X-axis directions is the same. The folded part 47 is the part formed by folding the plate constituting the positive terminal 6 and connecting the first piece 41 and the second piece 42.

[0045] In the following description, the boundary between the flat plate portion 15 and the positive terminal 6 will be referred to as the connecting portion 46 of the first piece portion 41. When the positive terminal 6 is pressed onto the terminal block 17 for assembly, the positive terminal 6 deforms as a whole (see reference). Figure 5 At this point, the connecting portion 46 becomes the starting point for the deformation of the first piece 41 and the second piece 42. The aforementioned folded portion 47 corresponds to the boundary between the first piece 41 and the second piece 42. The folded portion 47 is the part with the least displacement after deformation. Therefore, the folded portion 47 becomes the starting point for the deformation of the second piece 42. Furthermore, when "length" is mentioned in the following description regarding the positive end 6, it refers to the length corresponding to the neutral axis of the sheet metal constituting each piece 41, 42 of the positive end in a cross-sectional view along the X-axis. For example, the length of the first piece 41 is equal to the dimension in the Y-axis direction between the connecting portion 46 and the folded portion 47 of the sheet metal when the spring portion 50 is bent and stretched into a straight line.

[0046] A spring portion 50 is formed in the positive terminal 6 to alleviate the stress acting on it. This spring portion 50 can alleviate the stress acting on the positive terminal 6 after it has been assembled in a pressed state against the terminal block 17 using the fastening portion 32 and the nut 38.

[0047] Reference Figure 4 The detailed structure of the spring section 50 will be explained below. Furthermore, in the following descriptions, the term "reference shape" of the positive terminal 6 will sometimes be used. The reference shape refers to the shape of the positive terminal 6 without the spring section 50, specifically... Figure 7 The shapes shown are as follows. The cross-sectional shape of the first piece 41 in the reference shape extends parallel to the Y-axis direction between the connecting portion 46 and the bent portion 47, and extends in a straight line without bending in the middle. The cross-sectional shape of the second piece 42 in the reference shape extends parallel to the downward direction from the bent portion 47, and extends in a straight line without bending in the middle.

[0048] With the reference shape defined in this way, the spring portion 50 is defined as a location where the sheet metal is deformed and positioned differently from the reference shape, such that the length of the positive terminal 6 is longer than the length of the reference shape. In this embodiment, the spring portion 50 is formed on the first sheet portion 41. Therefore, the first sheet portion 41 is positioned at the location of the spring portion 50, extending from the reference shape SL ( Figure 4 (The deviation is shown in dashed lines.) On the other hand, the spring portion 50 is not formed in the second piece 42. Therefore, the second piece 42 has the same shape as the reference shape.

[0049] Specifically, between the connecting portion 46 and the through hole 43 of the positive terminal 6, there is a spring portion 50 that alleviates the stress acting on the positive terminal 6. The spring portion 50 has a bend portion 51 (first bend portion) formed by bending the sheet metal constituting the positive terminal 6 at a location other than the bend portion 47. The bend portion 51 is the portion where the sheet metal of the first piece 41 bends downward when viewed from the connecting portion 46. Furthermore, when viewed from the bend portion 47, the sheet metal is bent upward at the bend portion 51. In the following description of the bend portions 51 and 52, unless otherwise specified, the appearance shown is that when viewed from the connecting portion 46. Here, the bend portion 51 bends downward as the sheet metal of the first piece 41 moves toward the negative Y-axis direction. The bend portion 51 has bending points 51a and 51b for bending the sheet metal. A bending point 51a is formed at the end of the bent portion 51 on the positive side of the Y-axis direction, and a bending point 51b is formed at the end of the bent portion 51 on the negative side of the Y-axis direction. At bending point 51a, the sheet metal is bent in a downward-sloping manner. Furthermore, in this embodiment, bending point 51a is formed at the location of the connecting portion 46. At bending point 51b, the sheet metal is bent from a downward-sloping state back to a state parallel to the Y-axis direction. The first sheet portion 41 has an extension portion 53 extending parallel to the Y-axis direction from bending point 51b toward the negative side of the Y-axis direction.

[0050] The spring portion 50 also has a bend portion 52 (second bend portion) formed when the sheet metal is bent to the side opposite to the bend portion 51 when viewed from the connecting portion 46. The bend portion 52 is the portion where the sheet metal of the first piece portion 41 bends upward when viewed from the connecting portion 46. Here, the bend portion 52 bends upward as the sheet metal of the first piece portion 41 moves towards the negative side of the Y-axis direction. The bend portion 52 has bend points 52a and 52b for bending the sheet metal. The bend point 52a is formed at the end of the bend portion 52 on the positive side of the Y-axis direction, and the bend point 52b is formed at the end of the bend portion 52 on the negative side of the Y-axis direction. At the bend point 52a, the sheet metal is bent upward. At the bend point 52b, the sheet metal is bent from the upward-tilted state back to a state parallel to the Y-axis direction. The first piece 41 has an extension 54 that extends parallel to the Y-axis direction from the bending point 52b toward the negative side of the Y-axis direction.

[0051] Through the aforementioned bends 51 and 52, the extension 53 is positioned lower than the reference shape SL, that is, a position lower than the flat plate 15. The extension 54 is positioned at the same height as the reference shape SL, that is, at the same height as the flat plate 15. In other words, the first piece 41 has a shape such that it descends a certain distance at the bend 51 and returns to its original position at the bend 52.

[0052] Here, the extension 53 is disposed below the sealing member 14 of the energy storage module 3. The sealing member 14 extends to a position lower than the reference shape SL. That is, the sealing member 14 is configured to enter the concave shape formed by the bending portions 51 and 52 and the extension 53. Furthermore, the extension 53 is configured to enter the recess 27 of the insulating plate 20B. In this way, the first piece 41 allows the energy storage module 3 to be disposed in a low position while avoiding the insulating plate 20B and the sealing member 14 so as not to interfere with them. According to the above description, the energy storage device 1 can be made compact. In addition, with this structure, liquid from the energy storage module 3 can be received and drained by the recess 27. With the above configuration, the bending portion 51 is disposed in the space between the step portion 21b of the insulating plate 20B and the sealing member 14 in the Y-axis direction. The bending portion 52 is disposed in the space between the long side portion 27b of the recess 27 of the insulating plate 20B and the sealing member 14 in the Y-axis direction.

[0053] Next, the function / effect of the energy storage device 1 in this embodiment will be explained. Furthermore, the following functions / effects are also obtained in the structure on the current collector 5A side.

[0054] In the energy storage device 1, the current collector plate 5B has a positive terminal 6 for extracting current from the energy storage module 3, and the constraint plate 8B has a terminal block 17 connected to the positive terminal 6. Therefore, the positive terminal 6 can extract current to the terminal block 17 by connecting to the terminal block 17. Here, the positive terminal 6 has: a first plate portion 41, which is plate-shaped and extends from the outer edge portion 15a provided at the edge of the plate portion 15 in the Y-axis direction (orthogonal to the stacking direction) when viewed from the Z-axis direction (stack direction); a second plate portion 42, which extends in the Z-axis direction and has a through hole 43 for fixing the positive terminal 6 to the terminal block 17; and a bent portion 47, which is formed by bending the plate constituting the positive terminal 6 and connecting the first plate portion 41 and the second plate portion 42.

[0055] Here, refer to Figure 5 This describes the deformation of the positive terminal 6 during assembly with the second piece 42 pressed against the terminal block 17. Figure 5 The dashed line shows the deformed positive terminal 6. Additionally, within the dashed line, the stress distribution acting on the positive terminal 6 is shown. Darker colors indicate greater stress acting at those locations. Furthermore, in... Figure 5 In the diagram, to facilitate observation of stress distribution, the shadow lines for the positive terminal 6 are omitted. In L-shaped cross-sections such as the positive terminal 6, as... Figure 5 As shown, the bend 47 functions as one of the starting points for deformation during assembly to the terminal block 17. Furthermore, the distance between the bend 47 and the assembly position (through hole 43) to the terminal block 17 is short. Therefore, when the second piece 42 is assembled in a pressed-on state to the terminal block 17, the stress near the assembly position increases (for example, refer to stress concentration point RP1). If vibration occurs in this state, damage may occur at stress concentration point RP1, potentially causing breakage of the positive terminal 6. Moreover, portions like stress concentration point RP1 that bend as a result of stress during assembly, rather than manufacturing the positive terminal 6, are not considered bends in this invention.

[0056] To address this, a spring portion 50 is provided between the connection portion 46 and the through hole 43 of the positive terminal 6 and the outer edge portion 15a to alleviate the stress acting on the positive terminal 6. The spring portion 50 has at least a bent portion 51 formed by bending the sheet metal outside the bent portion 47. By forming this spring portion 50 between the connection portion 46 and the through hole 43 of the positive terminal 6, the stress concentrated near the assembly position of the positive terminal 6 can be alleviated. Figure 5As shown, in the positive terminal 6, in addition to the bending portion 47, the connecting portion 46 also functions as one of the starting points of deformation. Therefore, if a spring portion 50 is present at any point between the connecting portion 46 and the assembly position, the stress concentrated at the stress concentration point RP1 can be dispersed in the spring portion 50. Based on the above, the breakage of the positive terminal 6 of the current collector plate 5B during vibration can be suppressed. Furthermore, when the entire length of the positive terminal 6 is increased, the resistance increases. However, the inventors of this application found that the advantage of the stress relief effect outweighs the disadvantage of the increased resistance, and therefore adopted the above configuration.

[0057] As a comparative example, it is explained Figure 7 The positive terminal 106 is shown. The positive terminal 106 has a reference shape SL. (As shown...) Figure 7 As shown in (a), the positive terminal 106 of the reference shape SL does not have a spring portion formed in the first piece 141. Therefore, the length of the sheet material in the first piece 141 is shorter than that in the first piece 41 of this embodiment. This results in less bending of the first piece 141 (see reference). Figure 7 (a) (dashed line), the stress at the stress concentration point RP1 that can be dispersed by the first piece 141 is smaller than that in this embodiment. Therefore, the possibility of damage at the stress concentration point RP1 is greater.

[0058] The spring portion 50 has at least a bent portion 51 formed by bending the sheet metal constituting the positive terminal 6. By bending the sheet metal, the sheet metal of the positive terminal 6 can be lengthened accordingly. In this case, relative to the stress concentrated near the assembly position of the positive terminal 6, the positive terminal 6 as a whole can be bent more easily, thereby dispersing and mitigating stress. For example, as... Figure 5 As shown, the sheet metal becomes longer due to the presence of bends 51 and 52. Therefore, the first piece 41 (and) Figure 7 Compared to the first piece 141 of (a), it can bend upwards more significantly. In this way, the area near the bend 47 also bends gently, so by making the deformation near the stress concentration point RP gentle, the stress can be distributed throughout the entire positive end 6.

[0059] Furthermore, the spring section 50 alleviates the stress acting on the positive terminal 6. This helps to prevent breakage of the positive terminal 6 of the current collector plate 5B during vibration.

[0060] The spring portion 50 may also include a bending portion 52, which is formed by bending the sheet metal towards the side opposite to the bending portion 51 (upper side) when viewed from the connecting portion 46 of the first piece portion 41 relative to the flat plate portion 15. In this case, although the sheet metal of the first piece portion 41 is positioned at a different position from the reference shape SL by the bending portion 51, it can return to the original reference shape SL by the bending portion 52. Thus, the shape of the positive terminal 6 is maintained in a state that does not change excessively from the reference shape SL. For example, when using... Figure 8 In the case of the shape shown in (b), the position of the bend is also changed, so there is a possibility that the shape near the terminal block 17 needs to be redesigned. Regarding this, as... Figure 4 As shown, at the bending portion 52, the first piece 41 returns to its original reference shape SL, thus eliminating the need to change the shape near the terminal block 17. Furthermore, by bending the sheet metal upwards through the bending portion 52, the position of the bent portion 47 is increased, moving it away from the assembly position (through hole 43). Therefore, (with...) Figure 8 Compared to structure (b), it can reduce deformation near stress concentration points RP.

[0061] The spring portion 50 may also be formed on the first piece portion 41. The first piece portion 41 extends in the Y-axis direction, which is the direction intersecting the stacking direction. Therefore, when the vibration V1 in the stacking direction acts on the energy storage device 1, the first piece portion 41 will deform in a manner that alternately flexes to one side and the other side in the stacking direction (refer to deformation direction D1). Here, in the comparative example, the first piece portion 141 of the positive terminal 106 extends straight in the Y-axis direction throughout the entire area. Therefore, the nodes where the connecting portion 46 and the bending portion 47 are the vibration points will vibrate more (refer to deformation direction D2). In this case, it is possible that the first piece portion 141 and the upper energy storage module 3 (refer to...) will vibrate. Figure 4 The vibration is transmitted to the energy storage module 3 upon contact. In this embodiment, the spring portion 50 functions as a flexural node, thus reducing deformation caused by the vibration of the first piece 41. Specifically, as... Figure 6 As shown, extension 53 vibrates at the bends 51 and 52. Extension 54 vibrates at the bends 52 and 47. Since extensions 53 and 54 are shorter than the entire length of the first piece 141 of the reference shape SL, deformation is reduced. Therefore, contact between extensions 53 and 54 and the energy storage module 3 can be avoided, thus suppressing vibration transmission to the energy storage module 3.

[0062] The present invention is not limited to the embodiments described above.

[0063] For example, it can also be used Figure 8The positive terminal 206 is shown in (a). In the positive terminal 206, the bent portion 252 of the first piece 241 is raised more, and the extension 54 is positioned higher than the reference shape SL. In this case, the folded portion 247 between the first piece 241 and the second piece 242 is positioned higher than the connecting portion 46 of the first piece 241 relative to the flat plate portion 15 (the side opposite to the terminal block 17 in the stacking direction). In this case, the distance between the assembly position (through hole 43) of the second piece 242 with the terminal block 17 and the folded portion 247 can be increased. As mentioned above, the folded portion 247 functions as one of the starting points of deformation when assembled with the terminal block 17. Therefore, by increasing the distance between the assembly position and the folded portion 247, the amount of deformation increases, and the stress concentrated around the assembly portion can be alleviated.

[0064] Alternatively, one can use, such as Figure 8 As shown in (b), the positive terminal 306. In the positive terminal 306, the first piece 341 does not have a bent portion 52 (see reference). Figure 4 The extension 353, which descends from the reference shape SL, extends as is to the bend 347 between the second piece 342. In this way, even if the spring part 50 has only one bend 51, the plate can be lengthened and the vertical deformation during vibration can be reduced, thus achieving the same effect as described above.

[0065] Furthermore, in the above-described embodiments and variations, although the bending portion 51 bends the sheet metal downwards when viewed from the connecting portion 46, it may also bend the sheet metal upwards.

[0066] The position of the spring portion is not specific; it can be formed in the bent portion or in the second piece. Furthermore, the number of bent portions in the spring portion is not limited; it can be three or more.

[0067] Furthermore, in the above-described embodiments and variations, although the bent portion is straight and inclined, the bending pattern of the bent portion is not particularly limited. For example, the bent portion may be bent in a curved shape, or it may be bent in a stepped shape, or it may be bent in a manner where the inclination angle gradually changes.

[0068] Such a spring portion can be formed in at least one of the positive terminal 6 and the negative terminal 7.

Claims

1. An energy storage device, comprising: Energy storage module; A pair of current collectors, located at opposite ends of the energy storage device in a first direction, are stacked in the first direction such that they sandwich the energy storage module; and A pair of constraint plates constrain the aforementioned energy storage module and the aforementioned pair of current collectors in the aforementioned first direction. The aforementioned energy storage device is characterized in that, The above-mentioned energy storage module In the first direction described above, there are current extraction surfaces at both ends. At least one of the aforementioned pair of current collectors has: The flat plate portion is in electrical contact with the current extraction surface located on the same end side as the current collector plate in the first direction; and The extraction section, which is connected to the aforementioned flat plate section, extracts current from the aforementioned energy storage module. The above-mentioned extraction section has: The first piece extends from the outer edge of the plate portion to a second direction orthogonal to the first direction when viewed from the first direction. The boundary between the plate portion and the extraction portion is the connecting portion of the first piece. The second portion, extending in the first direction, has an assembly portion for attaching the extraction portion to a terminal block of one of the pair of constraint plates; and The folded section is formed by folding the sheet metal constituting the aforementioned take-out section, and connects the first piece and the second piece. Between the aforementioned connecting portion and the aforementioned assembly portion, there is a spring portion that alleviates the stress acting on the aforementioned extraction portion. The aforementioned spring portion includes: a first bending portion, which is formed by bending the aforementioned sheet metal at a location other than the aforementioned folded portion; a second bending portion; and an extension portion connecting the aforementioned first bending portion and the aforementioned second bending portion. The aforementioned first bend has a first bend point and a second bend point separate from the aforementioned first bend point. The aforementioned second bend has a third bend point and a fourth bend point that is separate from the aforementioned third bend point. The aforementioned extension connects the second bend point and the third bend point. The aforementioned energy storage device further includes a sealing member, which is frame-shaped and disposed on the side of the energy storage module. The extension is disposed below the sealing member in the first direction. The sealing member is configured to enter a concave shape formed by the first bend, the second bend, and the extension. The aforementioned energy storage device also includes an insulating plate disposed between the current collector plate and the constraint plate, the insulating plate having a recess, and the entire extension portion being located within the recess.

2. The energy storage device according to claim 1, wherein, The second bend is formed by bending the sheet metal to the side opposite to the first bend when viewed from the connection.

3. The energy storage device according to claim 1 or 2, wherein, The aforementioned spring portion is formed in the aforementioned first piece portion.

4. The energy storage device according to any one of claims 1 to 3, wherein, In the first direction, the distance between the bent portion and the terminal block is greater than the distance between the connecting portion and the terminal block.

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