Energy Storage Module

Abstract

This power storage module comprises: a plurality of power storage devices; a pair of end plates disposed on both ends of the plurality of power storage devices and having at least a first member and a second member which are mutually separate members; and a restraining member which restrains the plurality of power storage devices, and which has a main body part and a connecting arm part extending from the main body part and connecting to the pair of end plates. The first member has a fixing part to which the connecting arm part is fixed. The second member has a pressure receiving part which is interposed between the first member and the power storage devices and directly or indirectly contacts the power storage devices, and a pressing part which directly or indirectly contacts a base portion of the connecting arm part.

Description

[Technical field]

[0001] The present disclosure relates to an energy storage module. [Background technology]

[0002] For example, as a power source that requires a high output voltage for a vehicle, etc., a power storage module in which a plurality of power storage devices (e.g., batteries) are connected in series is known. In general, a power storage module includes a plurality of power storage devices, a pair of end plates disposed at both ends in the arrangement direction of the power storage devices, and a binding member (bind bar) that is stretched between the pair of end plates and binds the plurality of power storage devices in the arrangement direction (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2012-181972 A Summary of the Invention [Problem to be solved by the invention]

[0004] In general, energy storage devices expand due to various factors. In conventional energy storage modules, this expansion is suppressed by end plates and restraining members. However, in recent years, the capacity of energy storage devices has been increasing, and the amount of expansion of energy storage devices tends to increase. This increases the load on the restraining members, which may cause the restraining members to deform.

[0005] The present disclosure has been made in light of these circumstances, and one of its objectives is to provide a technique for suppressing deformation of a restraining member included in an energy storage module. [Means for solving the problem]

[0006] One aspect of the present disclosure is an energy storage module. The energy storage module includes a plurality of energy storage devices arranged in a first direction, a pair of end plates having at least a first member and a second member separate from each other and disposed at both ends of the plurality of energy storage devices in the first direction, and a restraining member having a main body portion extending in the first direction and connecting arms extending from the main body portion in a second direction intersecting the first direction and connected to the pair of end plates, and restraining the plurality of energy storage devices. The first member has fixing portions to which the connecting arms are fixed on both sides in the second direction, and the second member has a pressure receiving portion interposed between the first member and the energy storage devices in the first direction and in direct or indirect contact with the energy storage devices, and a pressing portion in direct or indirect contact with a base portion of the connecting arms located closer to the main body portion than the fixing portions.

[0007] Another aspect of the present disclosure is also an energy storage module. This energy storage module includes a plurality of energy storage devices arranged in a first direction, a pair of end plates having a hollow portion, a first portion, and a second portion and disposed at both ends of the plurality of energy storage devices in the first direction, a main body portion extending in the first direction, and a connecting arm portion extending from the main body portion in a second direction intersecting the first direction and connected to the pair of end plates, and a restraining member for restraining the plurality of energy storage devices. The first portion is located farther from the plurality of energy storage devices than the hollow portion, and has a fixing portion to which the connecting arm portion is fixed on both sides in the second direction. The second portion has a pressure receiving portion located closer to the plurality of energy storage devices than the hollow portion and in direct or indirect contact with the energy storage devices, and a pressing portion connecting the pressure receiving portion and the first portion, and in direct or indirect contact with a base located closer to the body portion than the fixing portion of the connecting arm portion.

[0008] Any combination of the above components and any conversion of the expression of the present disclosure between a method, an apparatus, a system, etc. are also valid as aspects of the present disclosure. Effect of the Invention

[0009] According to the present disclosure, it is possible to suppress deformation of the restraining member included in the energy storage module. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a perspective view of an electricity storage module according to a first embodiment. [Diagram 2] FIG. 2 is an exploded perspective view of the electricity storage module. [Diagram 3] 3(A) and 3(B) are cross-sectional views that typically show how the electricity storage device expands. [Figure 4] 3 is an enlarged cross-sectional view showing an end region of the electricity storage module according to the first embodiment. FIG. [Diagram 5] 11 is an enlarged cross-sectional view showing an end region of an electricity storage module according to a second embodiment. FIG. [Figure 6] Fig. 6(A) is an exploded perspective view of an end plate according to Modification 1. Fig. 6(B) is a cross-sectional view of the end plate according to Modification 1. [Figure 7] Fig. 7(A) is a schematic cross-sectional view showing an enlarged portion of an end plate according to Modification 2. Fig. 7(B) is a schematic cross-sectional view showing an enlarged portion of an end plate according to Modification 3. Fig. 7(C) is a schematic cross-sectional view showing an enlarged portion of an end plate according to Modification 4. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] The present disclosure will be described below with reference to the drawings based on preferred embodiments. The embodiments are illustrative and do not limit the present disclosure, and all features and combinations thereof described in the embodiments are not necessarily essential to the present disclosure. The same or equivalent components, members, and processes shown in each drawing are given the same reference numerals, and duplicated descriptions are omitted as appropriate. In addition, the scale and shape of each part shown in each drawing are set for convenience to facilitate explanation, and are not to be interpreted as being limiting unless otherwise specified. In addition, when terms such as "first" and "second" are used in this specification or claims, unless otherwise specified, these terms do not represent any order or importance, but are intended to distinguish one configuration from another. In addition, some of the members that are not important in explaining the embodiment in each drawing are omitted.

[0012] (Embodiment 1) Fig. 1 is a perspective view of an electricity storage module according to embodiment 1. Fig. 2 is an exploded perspective view of the electricity storage module. The electricity storage module 1 includes a battery stack 2 and a pair of restraining members 4. The battery stack 2 has a plurality of electricity storage devices 6, a plurality of separators 8, and a pair of end plates 10.

[0013] Each power storage device 6 is, for example, a rechargeable secondary battery such as a lithium ion battery, a nickel-hydrogen battery, or a nickel-cadmium battery, or a capacitor such as an electric double layer capacitor. The power storage device 6 of this embodiment is a so-called prismatic battery, and has a housing 12 having a flat rectangular parallelepiped shape. The housing 12 is composed of an exterior can 14 and a sealing plate 16. The exterior can 14 has a substantially rectangular opening on one side, and an electrode body 18 (see FIG. 3(A)), an electrolyte, etc. are accommodated in the exterior can 14 through this opening.

[0014] As shown in FIG. 3(A), the electrode body 18 has a structure in which a plurality of positive electrodes 18a, a plurality of negative electrodes 18b, and a plurality of porous separators 18c, each of which is in the form of a sheet, are laminated. The positive electrodes 18a and the negative electrodes 18b are alternately arranged in a first direction X, and the porous separator 18c is disposed between the positive electrodes 18a and the negative electrodes 18b. Each positive electrode 18a and each negative electrode 18b has a lead 20 extending from an end of the laminate toward the sealing plate 16. The lead 20 is connected to an output terminal 22 directly or via a current collecting member. The electrode body 18 may be a wound body having a structure in which a strip-shaped positive electrode and a strip-shaped negative electrode are wound with a porous separator interposed therebetween.

[0015] The exterior can 14 may be covered with an insulating film (not shown) such as a shrink tube. By covering the surface of the exterior can 14 with an insulating film, it is possible to suppress short circuits between adjacent power storage devices 6 and between the power storage devices 6 and the end plates 10 and between the power storage devices 6 and the restraining members 4. A sealing plate 16 that closes the opening and seals the exterior can 14 is provided at the opening of the exterior can 14. The exterior can 14 and the sealing plate 16 are conductive and are made of metal such as aluminum, iron, stainless steel, etc. The exterior can 14 and the sealing plate 16 are joined together by, for example, a laser, friction stir welding, brazing, etc. Alternatively, the exterior can 14 and the sealing plate 16 are made of insulating resin.

[0016] An output terminal 22 electrically connected to the positive electrode 18a of the electrode body 18 is provided near one end of the sealing plate 16 in the longitudinal direction, and an output terminal 22 electrically connected to the negative electrode 18b of the electrode body 18 is provided near the other end. Hereinafter, the output terminal 22 connected to the positive electrode will be referred to as the positive electrode terminal 22a, and the output terminal 22 connected to the negative electrode will be referred to as the negative electrode terminal 22b, as appropriate. Furthermore, when it is not necessary to distinguish the polarity of the pair of output terminals 22, the positive electrode terminal 22a and the negative electrode terminal 22b will be collectively referred to as the output terminals 22.

[0017] The exterior can 14 has a bottom surface facing the sealing plate 16 and four side surfaces connecting the opening and the bottom surface. Two of the four side surfaces are a pair of long side surfaces connected to two opposing long sides of the opening. Each long side surface is the surface with the largest area among the surfaces of the exterior can 14, i.e., the main surface. The remaining two side surfaces excluding the two long side surfaces are a pair of short side surfaces connected to the short sides of the opening of the exterior can 14. In the description of the present embodiment, for convenience, the bottom surface, long side surface, and short side surface of the exterior can 14 are respectively referred to as the bottom surface, long side surface, and short side surface of the housing 12 or the power storage device 6. Also, the sealing plate 16 is referred to as the top surface of the housing 12 or the power storage device 6.

[0018] In addition, in the energy storage module 1, the surface on the upper side of the energy storage device 6 is the upper surface of the energy storage module 1, the surface on the bottom side of the energy storage device 6 is the bottom surface of the energy storage module 1, and the surface on the short side of the energy storage device 6 is the side of the energy storage module 1. In addition, the upper side of the energy storage module 1 is the upper side in the vertical direction, and the bottom side of the energy storage module 1 is the lower side in the vertical direction. These directions and positions are defined for convenience. Therefore, for example, the part defined as the upper surface in this disclosure does not necessarily mean that it is located higher than the part defined as the bottom surface. Therefore, the sealing plate 16 is not necessarily located higher than the bottom surface of the exterior can 14. In addition, hereinafter, the direction in which the multiple energy storage devices 6 are arranged (stacked) is defined as the first direction X, the direction in which the two output terminals 22 are aligned is defined as the second direction Y, and the direction in which the upper surface and the bottom surface of the energy storage device 6 are aligned is defined as the third direction Z. The first direction X, the second direction Y, and the third direction Z are perpendicular to each other.

[0019] A safety valve (not shown) is provided on the sealing plate 16 between the pair of output terminals 22. The safety valve is configured to open when the internal pressure of the housing 12 rises to or above a predetermined value, thereby allowing the gas inside the housing 12 to be released. The safety valve is configured, for example, by a thin-walled portion that is provided in a portion of the sealing plate 16 and is thinner than other portions, and a linear groove formed in the surface of the thin-walled portion. In this configuration, when the internal pressure of the housing 12 rises, the thin-walled portion tears starting from the groove, opening the safety valve.

[0020] The multiple power storage devices 6 are arranged at predetermined intervals in the first direction X such that the long sides of adjacent power storage devices 6 face each other. The output terminals 22 of each power storage device 6 are arranged to face the same direction. In this embodiment, the output terminals 22 of each power storage device 6 are arranged to face vertically upward for convenience. Note that the output terminals 22 of each power storage device 6 may be arranged to face different directions.

[0021] Two adjacent power storage devices 6 are arranged so that the positive electrode terminal 22a of one power storage device 6 and the negative electrode terminal 22b of the other power storage device 6 are adjacent to each other. The positive electrode terminal 22a and the negative electrode terminal 22b are connected in series via a bus bar (not shown). Note that the output terminals 22 of the same polarity in a plurality of adjacent power storage devices 6 may be connected in parallel with each other via a bus bar to form a power storage device block, and the power storage device blocks may be connected in series with each other.

[0022] The separator 8 is also called an insulating spacer, and is flat and disposed between the opposing long sides of two adjacent electricity storage devices 6. This electrically insulates the two electricity storage devices 6. The separator 8 is made of, for example, an insulating resin. Examples of the resin constituting the separator 8 include thermoplastic resins such as polypropylene (PP), polybutylene terephthalate (PBT), polycarbonate (PC), and Noryl (registered trademark) resin (modified PPE). A plurality of electricity storage devices 6 and a plurality of separators 8 are alternately laminated. In addition, the separator 8 is also disposed between the electricity storage device 6 and the end plate 10. This insulates the electricity storage device 6 from the end plate 10.

[0023] The pair of end plates 10 are disposed on both ends of the multiple power storage devices 6 in the first direction X. The multiple power storage devices 6 and the multiple separators 8 arranged side by side are sandwiched between the pair of end plates 10 in the first direction X. The end plates 10 are made of, for example, a metal plate or a resin plate. The end plates 10 are provided with screw holes 26 into which screws 24 serving as fixing members are screwed. The structure of the end plates 10 will be described in detail later.

[0024] The pair of restraining members 4, also called bind bars, are elongated members with the first direction X as their longitudinal direction. The pair of restraining members 4 are arranged to face each other in the second direction Y. The battery stack 2 is interposed between the pair of restraining members 4. The pair of restraining members 4 may be connected by a connecting portion (not shown) that extends around the battery stack 2 and connects the two restraining members 4. Each of the restraining members 4 has a main body 28 and a pair of connecting arms 30.

[0025] The main body 28 is a rectangular plate-like body extending in the first direction X. The main body 28 extends parallel to the short side surfaces of each of the power storage devices 6. The pair of connecting arms 30 are plate-like bodies extending in the second direction Y from both ends of the main body 28 in the first direction X. The pair of connecting arms 30 face each other in the first direction X. Each connecting arm 30 is provided with a through hole 32 through which the screw 24 is inserted. The connecting arm 30 has a tip portion 45 in which the through hole 32 is arranged and which is fixed to a fixing portion 38 (see FIG. 4 ) of the first member 34, and a base portion 46 located closer to the main body 28 than the tip portion 45.

[0026] The restraint member 4 is fixed to the battery stack 2 by connecting the pair of connecting arms 30 to the pair of end plates 10. The main body 28 and the pair of connecting arms 30 can be formed, for example, by bending both ends of a metal plate. In this case, the parts from the bent position to the tips become the connecting arms 30, and the remaining parts become the main body 28. Note that the end plates 10 may be made of resin as long as a predetermined level of rigidity can be obtained.

[0027] The energy storage module 1 is assembled, for example, as follows. A plurality of energy storage devices 6 and a plurality of separators 8 are arranged alternately and sandwiched between a pair of end plates 10 in a first direction X to form a battery stack 2. The battery stack 2 is sandwiched between a pair of restraining members 4 in a second direction Y. Each restraining member 4 is aligned so that its through hole 32 overlaps with a screw hole 26 of the end plate 10. In this state, a screw 24 is inserted into the through hole 32 and screwed into the screw hole 26.

[0028] In this manner, the pair of restraining members 4 engage with the pair of end plates 10 to restrain the multiple energy storage devices 6. Each energy storage device 6 is fastened in the first direction X by the restraining members 4, and is positioned in the first direction X. The connecting arm 30 and the end plate 10 may be fixed by welding or the like. The surface of the restraining member 4 facing the battery stack 2 may be covered with an insulating sheet (not shown).

[0029] As an example, after completing these positioning steps, a bus bar is attached to the output terminal 22 of each power storage device 6, and the output terminals 22 of the multiple power storage devices 6 are electrically connected to each other. For example, the bus bar is fixed to the output terminal 22 by welding. The top surface of the battery stack 2 is then covered with a cover member (not shown). The cover member prevents condensed water, dust, and the like from coming into contact with the output terminals 22, bus bar, safety valve, and the like. The cover member is made of, for example, insulating resin, and can be fixed to the top surface of the battery stack 2 by a well-known fixing structure (not shown) including screws or a well-known locking mechanism.

[0030] 3(A) and 3(B) are cross-sectional views that typically show the expansion of the electricity storage device 6. In FIG. 3(A), the number of electricity storage devices 6 is reduced. Also, in FIG. 3(A) and FIG. 3(B), the structure of each part is simplified.

[0031] As shown in FIG. 3(A), an electrode body 18 is housed inside each power storage device 6. In the power storage device 6, the exterior can 14 repeatedly expands and contracts as the device is charged and discharged. The expansion of the exterior can 14 is caused by, for example, the expansion of the electrode body 18. Therefore, the central part of the exterior can 14 expands more than the peripheral part. When the exterior can 14 of each power storage device 6 expands, a force F1 acting outward in the first direction X is generated in the battery stack 2. Meanwhile, a reaction force F2 corresponding to the force F1 is applied to the battery stack 2 by the restraining member 4. This suppresses the expansion of each power storage device 6.

[0032] In a structure in which the restraining members 4 restrain a plurality of electric storage devices 6, a load is applied to the restraining members 4 when the electric storage devices 6 expand. When the amount of expansion increases due to the increase in the capacity of the electric storage devices 6, the load applied to the restraining members 4 also increases. When the load applied to the restraining members 4 becomes excessive, the restraining members 4 may be deformed. Specifically, as shown in FIG. 3B, in this embodiment, the connecting arm 30 is fixed to both ends of the end plate 10 in the second direction Y. Therefore, when the electric storage devices 6 expand, the end plate 10 is deformed so that the center portion bulges outward. When such deformation occurs in the end plate 10, the connecting arm 30 is deformed so as to open outward from the electric storage module 1. In particular, when the dimension of the electric storage devices 6 in the second direction Y is increased in order to increase the capacity, the end plate 10 also extends in the second direction Y and becomes more likely to bend, so that the connecting arm 30 is more likely to open outward.

[0033] If the connecting arm 30 opens outward, excessive stress is generated at the connection between the main body 28 and the connecting arm 30, and the restraining member 4 may be damaged. If the strength of the restraining member 4 is increased to prevent damage, this may lead to an increase in the size and cost of the restraining member 4 and the energy storage module 1. Furthermore, if the connecting arm 30 opens outward, the end plate 10 may move in a direction away from the energy storage device 6. If the end plate 10 moves, the restraint of the energy storage device 6 is loosened, and a shift S in the first direction X occurs in the energy storage device 6. If the energy storage device 6 is shifted in the first direction X, the energy storage device 6 may fall off or the electrical connection between adjacent energy storage devices 6 may become unstable.

[0034] In contrast, in the present embodiment, the restraining member 4 and the end plate 10 have a connecting structure described below, thereby suppressing deformation of the restraining member 4. FIG. 4 is an enlarged cross-sectional view showing an end region of the energy storage module 1 according to the first embodiment. In FIG. 4, the internal structure of the energy storage device 6 is simplified. Each end plate 10 has at least a first member 34 and a second member 36 that are separate from each other. The end plate 10 in the present embodiment is composed of only the first member 34 and the second member 36, but may include other members such as a third member and a fourth member.

[0035] The first member 34 has a flat plate shape extending in the second direction Y and the third direction Z, and has fixing portions 38 to which the connecting arm portions 30 are fixed on both sides in the second direction Y. The fixing portions 38 are provided with screw holes 26. The second member 36 has a flat plate shape extending in the second direction Y and the third direction Z, and has a recess 40 on a main surface facing away from the electricity storage device 6. Therefore, the second member 36 has a U-shaped cross section along the XY plane parallel to the first direction X and the second direction Y. The first member 34 is housed in the recess 40.

[0036] The second member 36 has a pressure receiving portion 42 and a pressing portion 44. The pressure receiving portion 42 is interposed between the first member 34 and the electricity storage device 6 in the first direction X, directly or indirectly contacts the electricity storage device 6, and receives a force F1 from the electricity storage device 6. The pressing portion 44 directly or indirectly contacts a base portion 46 located closer to the main body portion 28 than the fixing portion 38 in the connecting arm portion 30. In the second member 36 having a U-shape, a bottom surface facing the electricity storage device 6 constitutes the pressure receiving portion 42, and a pair of side surfaces extending in the first direction X from both ends of the pressure receiving portion 42 in the second direction Y constitute the pressing portion 44. As a case where the pressing portion 44 indirectly contacts the base portion 46, a case where the pressing portion 44 contacts the base portion 46 via the insulating sheet when the surface of the restraining member 4 is covered with the insulating sheet described above is assumed.

[0037] When a force F1 is input from the electricity storage device 6 to the pressure receiving portion 42, the second member 36 is displaced or deformed independently of the first member 34. As a result, the pressing portion 44 of the second member 36 presses the base portion 46. The force F1 generated by the expansion of the electricity storage device 6 is guided to the base portion 46, and the base portion 46, which is closer to the connection portion of the main body portion 28 and the connecting arm portion 30 than the fixing portion 38, receives the force F1, thereby reducing the moment of force generated in the connecting arm portion 30 and suppressing deformation of the connecting arm portion 30. This makes it possible to reduce stress generated in the connection portion between the base portion 46 and the main body portion 28 and also suppress displacement of the electricity storage device 6.

[0038] Further, the end plate 10 has a gap 48 interposed between the first member 34 and the pressure receiving portion 42. In this embodiment, the depth (size in the first direction X) of the recess 40 is greater than the thickness (size in the first direction X) of the fixed portion 38. The first member 34 is fixed to the tip portion 45, and the pressing portion 44 abuts against the base portion 46. This provides the gap 48 between the first member 34 and the pressure receiving portion 42. Due to the presence of the gap 48, the pressure receiving portion 42 is easily displaced in the first direction X when the electricity storage device 6 expands. Therefore, a part of the force F1 from the electricity storage device 6 can be absorbed by the pressure receiving portion 42. This allows the load applied to the restraining member 4 to be reduced. The gap 48 does not have to be provided. That is, the first member 34 and the second member 36 may be in contact with each other. Even in this case, since the first member 34 is only in contact with the second member 36, the first member 34 can be prevented from following the displacement or deformation of the second member 36.

[0039] Moreover, the restraining member 4 excessively restrains the expansion of the electricity storage device 6, and it is possible to avoid application of an excessive load to the electrode body 18, particularly the porous separator 18c. This makes it possible to suppress a decrease in performance and a shortened lifespan of the electricity storage device 6. Furthermore, it is possible to suppress the force F1 from being transmitted to the first member 34, and it is possible to further suppress deformation of the connecting arm portion 30.

[0040] Furthermore, the width of the recess 40 (the size in the second direction Y and the third direction Z) is larger than the width of the first member 34 (the size in the second direction Y and the third direction Z). As a result, the gap 48 extends to between the first member 34 and the pressing portion 44. By having the gap 48 extend to between the first member 34 and the pressing portion 44, the second member 36 becomes more easily displaced. This makes it easier to transmit the force F1 to the base 46.

[0041] Moreover, the pressure-receiving portion 42 overlaps with the electrode body 18 when viewed from the first direction X. Moreover, the pressure-receiving portion 42 is disposed between the two fixed portions 38 when viewed from the first direction X. This enables the force F1 generated by the expansion of the electricity storage device 6 to be received by the pressure-receiving portion 42 more reliably and transmitted to the base 46.

[0042] The pressure receiving portion 42 may be disposed in a region excluding the area between the two fixing portions 38 as viewed from the first direction X. For example, the pressure receiving portion 42 may be disposed so as to contact only the vicinity of the outer edge portion of the housing 12. In this case, the second member 36 may be an annular frame. Alternatively, the second member 36 may be divided into a plurality of parts, and each part may be arranged in the second direction Y in which the pair of restraining members 4 are arranged. For example, the second member 36 is composed of a first part including one pressing portion 44 and a second part including the other pressing portion 44. The first part and the second part each have the pressure receiving portion 42 on the opposite side to the pressing portion 44 in the first direction X. Also, the dimension (thickness) of the pressure receiving portion 42 in the first direction X may be smaller than the dimension of the pressing portion 44 in the second direction Y. In this case, the pressure receiving portion 42 becomes thinner and therefore more easily deformed. This makes it easier for the pressure receiving portion 42 to absorb the expansion of the electricity storage device 6. As a result, the force F1 transmitted from the pressure-receiving portion 42 to the pressing portion 44 can be weakened, and therefore the force with which the pressing portion 44 presses the base portion 46 can be weakened.

[0043] As described above, the energy storage module 1 according to this embodiment includes a plurality of energy storage devices 6 arranged in a first direction X, a pair of end plates 10 each having at least a first member 34 and a second member 36 separate from each other and arranged at both ends of the plurality of energy storage devices 6 in the first direction X, and a restraining member 4 having a main body portion 28 extending in the first direction X and connecting arm portions 30 extending from the main body portion 28 in a second direction Y intersecting the first direction X and connected to the pair of end plates 10, thereby restraining the plurality of energy storage devices 6.

[0044] The first member 34 has fixing portions 38 to which the connecting arm portion 30 is fixed on both sides in the second direction Y. The second member 36 has a pressure receiving portion 42 that is interposed between the first member 34 and the electricity storage device 6 in the first direction X and that directly or indirectly contacts the electricity storage device 6, and a pressing portion 44 that directly or indirectly contacts a base portion 46 that is located on the connecting arm portion 30 closer to the main body portion 28 than the fixing portion 38. By providing the end plate 10 with such a structure, it is possible to suppress deformation of the restraining member 4 when the electricity storage device 6 expands. Furthermore, by suppressing deformation of the restraining member 4, it is possible to suppress damage to the restraining member 4. Furthermore, it is possible to suppress displacement of the electricity storage device 6.

[0045] Moreover, the end plate 10 has a gap 48 interposed between the first member 34 and the pressure-receiving portion 42. This can reduce the load applied to the restraining member 4. Also, deterioration in performance and shortening of the life of the electricity storage device 6 can be suppressed.

[0046] Moreover, the power storage device 6 has a housing 12, and an electrode body 18 having a positive electrode 18a and a negative electrode 18b aligned in the first direction X and housed in the housing 12, and the pressure-receiving portion 42 overlaps with the electrode body 18 when viewed from the first direction X. Furthermore, the pressure-receiving portion 42 is disposed between the two fixed portions 38 when viewed from the first direction X. This makes it possible to further suppress deformation of the restraining member 4.

[0047] (Embodiment 2) Except for the shape of the end plate 10, the second embodiment has a common configuration with the first embodiment. The following description of the second embodiment will focus on configurations that are different from the first embodiment, and common configurations will be explained briefly or omitted. Fig. 5 is an enlarged cross-sectional view of an end region of the energy storage module 1 according to the second embodiment. In Fig. 5, the internal structure of the energy storage device 6 is simplified.

[0048] The energy storage module 1 includes a plurality of energy storage devices 6, a pair of end plates 10, and a restraining member 4. The plurality of energy storage devices 6 are arranged in a first direction X. The pair of end plates 10 are disposed on both ends of the plurality of energy storage devices 6 in the first direction X. The restraining member 4 has a main body portion 28 and a connecting arm portion 30, and restrains the plurality of energy storage devices 6. The main body portion 28 extends in the first direction X. The connecting arm portion 30 extends from the main body portion 28 in a second direction Y intersecting the first direction X and is connected to the pair of end plates 10.

[0049] Each end plate 10 has a hollow portion 50, a first portion 52, and a second portion 54. The end plate 10 of the present embodiment is a plate having a trapezoidal cross section along the XY plane, with the first portion 52 and the second portion 54 forming an outer shell and the hollow portion 50 being disposed inside. The first portion 52 and the second portion 54 are integral. The first portion 52 is located farther from the multiple power storage devices 6 than the hollow portion 50. The first portion 52 also has fixing portions 38 on both sides in the second direction Y to which the connecting arm portion 30 is fixed.

[0050] The second portion 54 has a pressure receiving portion 42 and a pressing portion 44. The pressure receiving portion 42 is located closer to the plurality of electricity storage devices 6 than the hollow portion 50, contacts the electricity storage devices 6 directly or indirectly, and receives a force F1 from the electricity storage devices 6. The pressing portion 44 connects the pressure receiving portion 42 and the first portion 52, and contacts a base portion 46 directly or indirectly, which is located closer to the main body portion 28 than the fixing portion 38 of the connecting arm portion 30, and presses the base portion 46 when the force F1 is input to the pressure receiving portion 42. Such an end plate 10 can also suppress deformation of the restraining member 4 when the electricity storage devices 6 expand.

[0051] The dimension of the hollow portion 50 in the second direction Y may be larger than the distance between the two fixing portions 38 in the second direction Y. With this configuration, the base portion 46 is more likely to receive the force from the pressing portion 44 than the fixing portions 38. Also, the dimension (thickness) in the first direction X of the portion of the first portion 52 sandwiched between the two fixing portions 38 may be smaller than the dimension in the second direction Y of each pressing portion 44, in other words, the dimension in the second direction Y of each of the two portions of the second portion 54 arranged side by side with the hollow portion 50 therebetween. With this configuration, the portion of the first portion 52 sandwiched between the two fixing portions 38 is more likely to deform, so that the pressing portion 44 can apply force to the base portion 46 preferentially. Therefore, it is possible to more effectively suppress the force in the direction in which the connecting arm portion 30 opens outward from being transmitted to the fixing portion 38.

[0052] The above describes the embodiments of the present disclosure in detail. The above-mentioned embodiments merely show specific examples of implementing the present disclosure. The contents of the embodiments do not limit the technical scope of the present disclosure, and many design changes such as changes, additions, and deletions of components are possible within the scope of the invention defined in the claims. A new embodiment with a design change has the effects of each of the combined embodiments and modifications. In the above-mentioned embodiments, the contents for which such design changes are possible are emphasized by adding notations such as "in this embodiment" and "in this embodiment", but design changes are permitted even in contents without such notations. In addition, any combination of components included in each embodiment is also valid as an aspect of the present disclosure. The hatching on the cross section of the drawing does not limit the material of the object to which the hatching is added.

[0053] (Variation 1) Fig. 6(A) is an exploded perspective view of an end plate 10 according to Modification 1. Fig. 6(B) is a cross-sectional view of the end plate 10 according to Modification 1. Like the end plate 10 of the first embodiment, the end plate 10 of this modification has a first member 34 and a second member 36 that are separate from each other. The first member 34 is in the form of a flat plate extending in the second direction Y and the third direction Z. The second member 36 has a U-shaped cross section along the XY plane, and has a pressure-receiving portion 42 and a pressing portion 44.

[0054] The first member 34 of this modification has an upper convex portion 56 and a lower convex portion 58 that protrude in the first direction X from the upper and lower ends of the main surface facing the second member 36. The upper convex portion 56 and the lower convex portion 58 are both elongated extending in the second direction Y and face each other in the third direction Z. When the first member 34 and the second member 36 are combined, the pressure receiving portion 42 is sandwiched between the upper convex portion 56 and the lower convex portion 58. This allows the second member 36 to be supported by the first member 34. As a result, it is possible to prevent the second member 36 from falling off during the assembly of the energy storage module 1, etc. The locking structure between the first member 34 and the second member 36 is not limited to the combination of the upper convex portion 56 and the lower convex portion 58, and for example, a convex portion may be provided on one of the first member 34 and the second member 36 and a concave portion into which the convex portion fits may be provided on the other.

[0055] (Variation 2) Fig. 7(A) is a schematic cross-sectional view showing an enlarged portion of the end plate 10 according to Modification 2. Note that Fig. 7(A) also shows a portion of the restraining member 4. In the end plate 10 of this modification, the thickness T42 of the pressure-receiving portion 42 is greater than the thickness T34 of the first member 34. The thickness T42 is the dimension of the pressure-receiving portion 42 in the first direction X, and the thickness T34 is the dimension of the first member 34 in the first direction X. Furthermore, the thickness T42 is, for example, the average thickness of the pressure-receiving portion 42, and the thickness T34 is, for example, the average thickness of the first member 34.

[0056] As a result, in particular in the end plate 10 in which the first member 34 is housed in the second member 36, in other words, in which both sides of the first member 34 in the second direction Y are sandwiched by the pressing parts 44, the pressure receiving part 42 can be easily made thicker, and the protruding height of the pressing part 44 (the size from the end on the pressure receiving part 42 side to the end on the connecting arm part 30 side) can be made smaller. Therefore, when the pressure receiving part 42 receives a force F1 from the electricity storage device 6, it is possible to suppress the central part of the pressure receiving part 42 in the second direction Y from being curved and deformed so as to protrude more than the edge part (separate from the electricity storage device 6). By suppressing this curved deformation, it is possible to suppress the pressing part 44 from opening outward in the second direction Y. This makes it possible to easily transmit the force F1 input to the pressure receiving part 42 to the connecting arm part 30 via the pressing part 44. Although not shown in FIG. 7(A), the end plate 10 may have a gap between the first member 34 and the pressure receiving part 42. Furthermore, in the second member 36, the thickness of the pressure-receiving portion 42 may be greater than the protruding height of the pressing portion 44. This structure also makes it possible to prevent the pressing portion 44 from deforming so as to open outward in the second direction Y.

[0057] (Variation 3) FIG. 7(B) is a schematic cross-sectional view showing an enlarged portion of the end plate 10 according to the third modification. Note that FIG. 7(B) also shows a portion of the restraining member 4. In the end plate 10 of this modification, the pressure receiving portion 42 and the pressing portion 44 are separate bodies. The pressure receiving portion 42 has a flat plate portion 42a extending parallel to the YZ plane, and a recessed portion 42b provided on a main surface of the flat plate portion 42a facing the first member 34 side. The recessed portion 42b is provided in an area including the center of the pressure receiving portion 42 in the second direction Y. Therefore, the edge portion 43 of the flat plate portion 42a protrudes toward the first member 34 side beyond the bottom surface of the recessed portion 42b. The pressing portion 44 has a flat portion 44a that extends parallel to the YZ plane and is aligned in the first direction X with the flat portion 42a, and a protruding portion 44b that protrudes in the first direction X from an edge of the flat portion 44a in the second direction Y and contacts the connecting arm portion 30. The entire main surface of the flat portion 44a facing the pressure-receiving portion 42 extends parallel to the YZ plane, and the edge in the second direction Y contacts the edge 43 of the pressure-receiving portion 42.

[0058] By providing the recess 42b in the flat plate portion 42a, only the edge portion 43 abuts against the flat plate portion 44a. Therefore, a gap is formed between the flat plate portion 44a and an area of ​​the flat plate portion 42a other than the edge portion 43. This makes it possible to prevent the flat plate portion 44a from being pressed by the deformed flat plate portion 42a even if the flat plate portion 42a is curved and deformed by receiving the force F1 from the power storage device 6. This makes it possible to prevent the protrusion 44b from opening outward in the second direction Y. Therefore, it is possible to easily transmit the force F1 input to the pressure receiving portion 42 to the connecting arm portion 30 via the pressing portion 44. Although not shown in FIG. 7(B), the end plate 10 may have a gap between the first member 34 and the flat plate portion 44a.

[0059] (Variation 4) FIG. 7(C) is a schematic cross-sectional view showing an enlarged portion of the end plate 10 according to the fourth modification. Note that FIG. 7(C) also shows a portion of the restraining member 4. In this modification, the pressure receiving portion 42 and the pressing portion 44 are separate bodies, as in the third modification. The pressure receiving portion 42 has a flat plate portion 42a and a recessed portion 42b, and the pressing portion 44 has a flat plate portion 44a and a protruding portion 44b. The flat plate portion 44a in this modification is disposed in the recessed portion 42b while maintaining a gap between the flat plate portion 42a and the recessed portion 44b. The outer portion of the protruding portion 44b in the second direction Y abuts against the edge portion 43. The inner portion of the protruding portion 44b in the second direction Y is inclined so as to fall into the recessed portion 42b as it moves away from the edge portion 43 in the second direction Y, and is connected to the edge portion of the flat plate portion 44a.

[0060] By having the inclined portion, the protrusion 44b can be more effectively prevented from opening outward, compared to the case where the entire protrusion 44b protrudes parallel to the first direction X as in Modification 3. This makes it easier to transmit the force F1 input to the pressure-receiving portion 42 to the connecting arm portion 30 via the pressing portion 44. Although not shown in FIG. 7(C), the end plate 10 may have a gap between the first member 34 and the flat plate portion 44a. [Explanation of symbols]

[0061] REFERENCE SIGNS LIST 1 Energy storage module, 4 Restraint member, 6 Energy storage device, 10 End plate, 28 Main body portion, 30 Connecting arm portion, 34 First member, 36 Second member, 38 Fixed portion, 42 Pressure receiving portion, 44 Pressing portion, 46 Base portion, 48 Void portion, 50 Hollow portion, 52 First portion, 54 Second portion.

Claims

1. A plurality of power storage devices arranged in a first direction; a pair of end plates including at least a first member and a second member that are separate from each other and that are disposed at both ends of the plurality of power storage devices in the first direction; a restraining member that has a main body portion extending in the first direction and connecting arms extending from the main body portion in a second direction intersecting the first direction and connected to the pair of end plates, and that restrains the plurality of power storage devices; the first member has fixing portions to which the connecting arm portion is fixed on both sides in the second direction, the second member has a pressure receiving portion interposed between the first member and the power storage device in the first direction and in direct or indirect contact with the power storage device, and a pressing portion in direct or indirect contact with a base portion located closer to the main body portion than the fixed portion in the connecting arm portion, The pressure-receiving portion is disposed in a region excluding a region between the two fixed portions when viewed from the first direction. Energy storage module.

2. The end plate has a gap portion interposed between the first member and the pressure-receiving portion. The energy storage module according to claim 1 .

3. The power storage device includes a housing and an electrode body having a positive electrode and a negative electrode aligned in the first direction and housed in the housing; The pressure receiving portion overlaps with the electrode body when viewed from the first direction. The energy storage module according to claim 1 or 2.

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