Power storage module

Abstract

To provide a power storage module capable of ensuring strength.SOLUTION: A power storage module 4 includes an electrode laminate 11 and an outer seal 24. The electrode laminate 11 has a first end face 11a and a second end face 11b in a lamination direction, and a side face 11c extending in the lamination direction. The outer seal 24 has a side surface portion 25, a first protruding portion 26, a second protruding portion 27, a canopy 60, and a rib 70. The side surface portion 25 has a connection portion 25a to which the canopy 60 is connected, a first side surface portion 25b located between the connection portion 25a and the first protruding portion 26, and a second side surface portion 25c located between the connection portion 25a and the second protruding portion 27. The rib 70 connects the canopy 60 and the first side portion 25b. In a direction perpendicular to the side surface 11c, the second side surface portion 25c is thicker than the first side surface portion 25b.SELECTED DRAWING: Figure 9

Description

[Technical Field]

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

[0002] A known energy storage module includes a seal that includes a side portion provided on a side surface of an electrode stack and a pair of protruding portions that protrude from the side portion onto a pair of end surfaces of the electrode stack (see, for example, Patent Document 1). The energy storage unit described in Patent Document 1 includes a seal portion and a canopy portion formed on a long wall portion of the seal portion. The canopy portion includes an inclined portion with an inclined surface that extends downward as it moves away from the outer peripheral surface of the long wall portion in the horizontal direction. Liquid that accumulates in a gap between certain energy storage units drips from the gap onto the canopy portion and moves along the inclined surface of the canopy portion, thereby being separated from the gap between other energy storage units in the horizontal direction. This aims to prevent the liquid from entering the gap between other energy storage units. As a result, a short circuit (liquid junction) caused by the liquid can be prevented. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2020 / 138110 Summary of the Invention [Problem to be solved by the invention]

[0004] When the sealing portion of the energy storage unit described in Patent Document 1 is formed by resin injection molding, uneven thickness may occur between the pair of protruding portions. When uneven thickness occurs between the pair of protruding portions, it may not be possible to ensure the strength of the energy storage module.

[0005] An object of the present disclosure is to provide an electricity storage module that can ensure strength. [Means for solving the problem]

[0006] An energy storage module according to one embodiment of the present disclosure comprises an electrode stack including a plurality of stacked electrodes, and a seal provided around the electrode stack to seal between the electrodes, wherein the electrode stack has a first end face and a second end face in the stacking direction of the plurality of electrodes, and a side face extending in the stacking direction to connect the first end face and the second end face, wherein the seal has a side portion provided on the side face, a first protrusion protruding from the side face onto the first end face, a second protrusion protruding from the side face onto the second end face, an eave extending from the side face to the outside of the electrode stack, and a rib provided on the eave, wherein the side face has a connection portion to which the eave is connected, a first side portion located between the connection portion and the first protrusion, and a second side portion located between the connection portion and the second protrusion, wherein the rib connects the eave and the first side portion, and the second side portion is thicker than the first side portion in a direction perpendicular to the side face.

[0007] In this energy storage module, the rib is connected to the eaves and the first side surface portion of the side wall. Therefore, when injection molding is performed using the rib formation space (hereinafter simply referred to as the rib) as the resin injection port, the resin path from the rib to the formation space of the first side surface portion (hereinafter simply referred to as the first side surface portion) includes a path that passes through the eaves formation space (hereinafter simply referred to as the eaves) and a path that directly connects the rib and the first side surface portion without passing through the eaves. In contrast, the resin path from the rib to the formation space of the second side surface portion of the side wall (hereinafter simply referred to as the second side surface portion) is only a path that passes through the eaves. Therefore, the resin injected from the rib flows more easily into the first side surface portion than into the second side surface portion. Because the second side surface portion is thicker than the first side surface portion, the resin flows more easily through the second side surface portion than through the first side surface portion. Therefore, it is difficult for an imbalance to occur between the resin flowing into the formation space of the first protrusion located downstream of the first side surface portion (hereinafter simply referred to as the first protrusion) and the resin flowing into the formation space of the second protrusion located downstream of the second side surface portion (hereinafter simply referred to as the second protrusion).As a result, it is possible to prevent an imbalance in thickness between the first protrusion and the second protrusion.As a result, the strength of the energy storage module can be ensured.

[0008] The second side surface portion may have a thick portion at a position facing the rib across the eaves in the stacking direction.

[0009] The rib has a plate-shaped main body portion connecting the eaves and the first side portion, and a pillar portion spaced apart from the side portion and protruding from the eaves in the stacking direction, and the pillar portion may be thicker than the main body portion in a direction perpendicular to the stacking direction and parallel to the side surface.

[0010] The main body portion may be connected to the first side surface portion at a position spaced apart from the first protruding portion in the stacking direction.

[0011] The main body portion has a first main body portion connected to the first side portion and a second main body portion connected to the column portion, and the distance that the first main body portion is separated from the first protrusion portion in the stacking direction may be longer than the distance that the second main body portion is separated from the first protrusion portion in the stacking direction.

[0012] and a seal provided around the periphery of the electrode stack to seal between the electrodes. The electrode stack has a first end face and a second end face in the stacking direction, and a side face extending in the stacking direction to connect the first end face and the second end face. The seal has a side face portion provided on the side face, a first protruding portion protruding from the side face onto the first end face, a second protruding portion protruding from the side face onto the second end face, eaves extending from the side face to the outside of the electrode stack, and a rib provided on the eaves. The side face portion has a connection portion to which the eaves is connected, a first side face portion located between the connection portion and the first protruding portion, and a second side face portion located between the connection portion and the second protruding portion. The rib connects the eaves and the first side face portion to form a plate-shaped main body portion and the first side face portion. minutes and a column portion spaced apart from the eaves and protruding from the eaves in the stacking direction, the column portion being thicker than the main body portion in a direction perpendicular to the stacking direction and parallel to the side surface.

[0013] In this energy storage module, the rib is connected to the eaves and the first side surface portion of the side panel. Therefore, when injection molding is performed using the rib as a resin inlet, the resin has a path from the rib to the first side surface portion that bypasses the eaves and also a path that connects the rib to the first side surface portion directly without passing through the eaves. In contrast, the resin has only one path from the rib to the second side surface portion of the side panel that passes through the eaves. Therefore, the resin injected through the rib is more likely to flow into the first side surface portion than into the second side surface portion. In addition to a plate-shaped main body portion, the rib has a column portion that protrudes from the eaves and is spaced apart from the first side surface portion. Because the column portion is thicker than the main body portion, injection molding using the space where the column portion is formed (hereinafter simply referred to as the column portion) as a resin inlet makes it easier for the resin to flow into the eaves. This prevents the resin from flowing directly from the rib into the first side surface portion without passing through the eaves. In other words, the amount of resin flowing into the first side surface portion and the second side surface portion is less likely to be uneven compared to when the column portion has the same thickness as the main body portion. Therefore, the amount of resin flowing into the first protruding portion located downstream of the first side surface portion is less likely to be uneven compared to the amount of resin flowing into the second protruding portion located downstream of the second side surface portion. As a result, it is possible to prevent uneven thickness between the first protruding portion and the second protruding portion. As a result, the strength of the energy storage module can be ensured.

[0014] In the energy storage module according to the above-described another aspect, the main body portion may be connected to the first side surface portion at a position spaced apart from the first protruding portion in the stacking direction.

[0015] In the energy storage module according to the another aspect described above, the main body portion has a first main body portion connected to the first side portion and a second main body portion connected to the column portion, and the distance that the first main body portion is separated from the first protrusion portion in the stacking direction may be longer than the distance that the second main body portion is separated from the first protrusion portion in the stacking direction. [Effects of the Invention]

[0016] According to the present disclosure, it is possible to provide an electricity storage module that can ensure strength. [Brief explanation of the drawings]

[0017] [Figure 1] FIG. 1 is a schematic cross-sectional view showing a cross section including a first direction and a second direction of a power storage device according to one embodiment. [Figure 2] FIG. 2 is a schematic cross-sectional view showing a cross section including a first direction and a third direction of the power storage device according to one embodiment. [Figure 3] FIG. 3 is a schematic cross-sectional view showing the power storage module shown in FIGS. [Figure 4] FIG. 4 is a perspective view showing the electricity storage module shown in FIGS. 1 to 3. As shown in FIG. [Figure 5] FIG. 5 is an enlarged perspective view of the rib and its surroundings. [Figure 6] FIG. 6 is an enlarged perspective view of the rib and its surroundings. [Figure 7] FIG. 7 is an enlarged plan view showing the rib and its surroundings. [Figure 8] FIG. 8 is an enlarged side view of the rib and its surroundings. [Figure 9] FIG. 9 is an enlarged cross-sectional view showing the rib and its surroundings. [Figure 10] FIG. 10 is a cross-sectional view for explaining the inner seal forming step. [Figure 11] FIG. 11 is a cross-sectional view for explaining the outer seal forming step. DETAILED DESCRIPTION OF THE INVENTION

[0018] An embodiment of a power storage device will be described below with reference to the drawings. In the description of each drawing, the same or corresponding elements are given the same reference numerals, and duplicate explanations may be omitted. Each drawing also illustrates a Cartesian coordinate system configured with a first axis defining a first direction D1, a second axis defining a second direction D2, and a third axis defining a third direction D3. As an example, the first direction D1 is a vertical direction, and the second direction D2 and the third direction D3 are two horizontal directions that intersect with each other.

[0019] Fig. 1 is a schematic cross-sectional view showing a cross section including a first direction and a second direction of a power storage device according to an embodiment. Fig. 2 is a schematic cross-sectional view showing a cross section including a first direction and a third direction of a power storage device according to an embodiment. The power storage device 1 shown in Figs. 1 and 2 can be used as a battery for various vehicles such as forklifts, hybrid vehicles, and electric vehicles. The power storage device 1 includes a module stack 2 including a plurality of power storage modules 4 stacked along a first direction D1, and a restraining member 3 that applies a restraining load to the module stack 2 along the first direction D1.

[0020] The module stack 2 includes a plurality of (three in this example) storage modules 4 and a plurality of (two in this example) conductive plates 5. The storage modules 4 are, for example, bipolar batteries, and have a rectangular shape when viewed in the first direction D1. More specifically, the storage modules 4 have a rectangular shape having long sides and short sides when viewed in the first direction D1. The storage modules 4 are, for example, secondary batteries such as nickel-metal hydride batteries or lithium-ion batteries, or electric double layer capacitors. In the following description, a nickel-metal hydride secondary battery will be used as an example.

[0021] In the module stack 2, a conductive plate 5 is interposed between adjacent power storage modules 4 in the first direction D1. This allows the multiple power storage modules 4 to be electrically connected via the conductive plate 5. More specifically, each power storage module 4 has a positive terminal surface on one end surface in the first direction D1 and a negative terminal surface on the other end surface in the first direction D1, and the multiple stacked power storage modules 4 are connected in series via the conductive plate 5. A current collector 6 from which a positive terminal 6a is drawn is disposed on the outer side of the power storage module 4 located at one end of the module stack 2 in the first direction D1 and is electrically connected to the power storage module 4. Furthermore, a current collector 7 from which a negative terminal 7a is drawn is disposed on the outer side of the power storage module 4 located at the other end of the module stack 2 in the first direction D1 and is electrically connected to the power storage module 4. The power storage device 1 is charged and discharged using the positive terminal 6a and the negative terminal 7a.

[0022] A plurality of flow paths 5a for circulating a refrigerant such as air are provided inside the conductive plate 5. The flow paths 5a extend, for example, along a direction (here, a third direction D3) that intersects (is perpendicular to) the first direction D1 and the direction in which the positive electrode terminal 6a and the negative electrode terminal 7a are drawn out. The conductive plate 5 not only functions as a connecting member that electrically connects the power storage modules 4 to each other, but also functions as a heat dissipating member that dissipates heat generated in the power storage modules 4 by circulating a refrigerant through these flow paths 5a.

[0023] The restraint member 3 includes a pair of restraint plates 8 that sandwich the module stack 2 in the stacking direction, a plurality of fasteners 9 such as bolts that connect the restraint plates 8 together, and supports 10 that house the main bodies of the fasteners 9 (e.g., bolt shanks). The restraint plates 8 are rectangular metal plates that have an area slightly larger than the areas of the energy storage modules 4 and the conductive plates 5 when viewed from the first direction D1. The restraint plates 8 have a rectangular shape with long and short sides when viewed from the first direction D1. A plate-shaped insulating member F is provided on the inner surface of the restraint plate 8 (the surface facing the module stack 2). That is, the current collector plate 6 or current collector plate 7 and the insulating member F are interposed between the module stack 2 and the restraint plate 8. This provides insulation between the restraint plate 8 and the module stack 2 (more specifically, the current collector plates 6 and 7).

[0024] An insertion hole 8a is provided in an edge of one of the restraint plates 8 at a position that is outward from the module stack 2 when viewed from the first direction D1, and a screw hole 8b is provided in an edge of the other of the restraint plates 8 at a position that faces the insertion hole 8a. A fastener 9 is passed from the insertion hole 8a of one of the restraint plates 8 toward the screw hole 8b of the other of the restraint plates 8 and is screwed into the screw hole 8b of the other of the restraint plates 8. As a result, the energy storage module 4 and the conductive plate 5 are sandwiched between the restraint plates 8 and united as the module stack 2, and a restraint load is applied to the module stack 2 in the first direction.

[0025] In this way, the fasteners 9 are arranged outside the module stack 2, extend along the first direction D1, and fasten the pair of restraint plates 8 to each other along the first direction D1, thereby restraining the module stack 2. The support posts 10 are interposed between the pair of restraint plates 8, and extend along the first direction D1 together with the fasteners 9. The support posts 10 determine the distance between the pair of restraint plates 8 in the first direction D1, thereby determining the restraining force on the module stack 2.

[0026] In the energy storage device 1, a plurality of connection members, each consisting of one fastener 9 and one support 10 that houses the fastener 9, are arranged along the long side of the restraint plate 8 when viewed from the first direction D1. The connection members face each other in a direction along the short side of the restraint plate 8 when viewed from the first direction D1. The closer the facing connection members are to each other, the more uniformly a restraint load can be applied to the energy storage module 4 via the restraint plate 8.

[0027] Fig. 3 is a schematic cross-sectional view showing the energy storage module shown in Figs. 1 and 2. Fig. 4 is a perspective view showing the energy storage module shown in Figs. 1 to 3. As shown in Figs. 3 and 4, the energy storage module 4 includes an electrode stack 11 and a second seal portion 12 made of resin that seals the electrode stack 11. The electrode stack 11 includes a plurality of electrodes (a plurality of bipolar electrodes 14, one negative terminal electrode 18, and one positive terminal electrode 19) stacked along a first direction D1 with separators 13 interposed between them. Here, the stacking direction of the electrodes coincides with the stacking direction of the energy storage module 4.

[0028] The bipolar electrode 14 includes an electrode plate 15 having a first surface 15a and a second surface 15b opposite the first surface 15a, a positive electrode active material layer 16 provided on the first surface 15a, and a negative electrode active material layer 17 provided on the second surface 15b. In the electrode stack 11, the positive electrode active material layer 16 of one bipolar electrode 14 faces the negative electrode active material layer 17 of another bipolar electrode 14 adjacent to it in the first direction D1 with the separator 13 interposed therebetween. In the electrode stack 11, the negative electrode active material layer 17 of one bipolar electrode 14 faces the positive electrode active material layer 16 of yet another bipolar electrode 14 adjacent to it in the first direction D1 with the separator 13 interposed therebetween.

[0029] The negative electrode terminal electrode 18 includes an electrode plate 15 and a negative electrode active material layer 17 provided on a second surface 15b of the electrode plate 15. No active material layer is provided on a first surface 15a of the electrode plate 15 of the negative electrode terminal electrode 18. The negative electrode terminal electrode 18 is disposed at one end of the electrode stack 11 in the first direction D1 so that the second surface 15b is on the inner side of the electrode stack 11 (the center side in the first direction D1). The negative electrode active material layer 17 of the negative electrode terminal electrode 18 faces the positive electrode active material layer 16 of the bipolar electrode 14 at one end in the first direction D1, with the separator 13 interposed therebetween.

[0030] The positive terminal electrode 19 includes an electrode plate 15 and a positive electrode active material layer 16 provided on a first surface 15a of the electrode plate 15. No active material layer is provided on a second surface 15b of the electrode plate 15 of the positive terminal electrode 19. The positive terminal electrode 19 is disposed at the other end of the electrode stack 11 in the first direction D1 so that the first surface 15a is on the inner side of the electrode stack 11. The positive electrode active material layer 16 of the positive terminal electrode 19 faces the negative electrode active material layer 17 of the bipolar electrode 14 at the other end in the first direction D1, with the separator 13 interposed therebetween.

[0031] The first surface 15a of the electrode plate 15 of the negative terminal electrode 18 is the surface facing the outside of the electrode stack 11. A conductive plate 5 is electrically connected to the first surface 15a of the negative terminal electrode 18 via a metal plate 50 described later. In addition, the second surface 15b of the electrode plate 15 of the positive terminal electrode 19 is the surface facing the outside of the electrode stack 11. Another conductive plate 5 is electrically connected to the second surface 15b of the positive terminal electrode 19 via a metal plate 50 described later.

[0032] The electrode plate 15 is made of a metal such as nickel or a nickel-plated steel plate. As an example, the electrode plate 15 is a rectangular metal foil made of nickel. The peripheral portion 15c of the electrode plate 15 (the peripheral portion of the bipolar electrode 14, the negative terminal electrode 18, and the positive terminal electrode 19) has a rectangular frame shape and is an area where the positive electrode active material layer 16 and the negative electrode active material layer 17 are not formed. An example of a positive electrode active material that constitutes the positive electrode active material layer 16 is nickel hydroxide. An example of a negative electrode active material that constitutes the negative electrode active material layer 17 is a hydrogen storage alloy.

[0033] The separator 13 is formed, for example, in the shape of a sheet. Examples of the separator 13 include a porous film made of a polyolefin resin such as polyethylene (PE) or polypropylene (PP), and a woven or nonwoven fabric made of polypropylene, polyethylene terephthalate (PET), methyl cellulose, etc. The separator 13 may be reinforced with a vinylidene fluoride resin compound.

[0034] The electrode stack 11 includes a plurality of first seal portions 21 made of insulating resin. Each of the plurality of first seal portions 21 includes a first portion 21a, a second portion 21b, and a third portion 21c. The first portion 21a is formed in a rectangular frame shape when viewed from the first direction D1 and is joined (e.g., welded) to a peripheral portion 15c of the electrode plate 15. The second portion 21b has a rectangular frame shape when viewed from the first direction D1 and is disposed on a portion of the first portion 21a. That is, when viewed from the first direction D1, the inner edge of the second portion 21b is positioned outside the inner edge of the first portion 21a. The peripheral portion of the separator 13 is disposed in a portion of the first portion 21a that is exposed from the second portion 21b and is joined (e.g., welded) to the portion.

[0035] The third portion 21c has a rectangular cylindrical shape extending along the first direction D1, and is formed by joining together the multiple first portions 21a and the multiple second portions 21b. The first portion 21a and the second portion 21b may be formed, for example, by folding a single sheet-like member. In this case, the third portion 21c is a welded end portion formed, for example, by welding together the folded portions (the outer ends of the first portion 21a and the second portion 21b) of the sheet-like member that are aligned in the first direction D1. The third portion 21c does not necessarily have to be provided around the entire periphery of the first seal portion 21, but may be provided partially around the periphery of the first seal portion 21.

[0036] The electrode stack 11 has a first end face 11a and a second end face 11b in the first direction D1, and a side face 11c extending in the first direction D1 to connect the first end face 11a and the second end face 11b. The first end face 11a is formed by the outer surface of a metal plate 50 that constitutes the negative electrode terminal surface of the energy storage module 4 and the outer surface of a first seal portion 21 provided on the metal plate 50. The second end face 11b is formed by the outer surface of a metal plate 50 that constitutes the positive electrode terminal surface of the energy storage module 4 and the outer surface of the first seal portion 21 provided on the metal plate 50. The side face 11c is formed by the outer surface of a third portion 21c.

[0037] The second seal portion 12 is formed of, for example, an insulating resin and has an overall rectangular cylindrical shape. The second seal portion 12 is provided around the electrode stack 11 so as to surround the electrode stack 11. The second seal portion 12 is formed, for example, by injection molding of resin, and extends over the entire length of the electrode stack 11 in the first direction D1.

[0038] The second seal portion 12 has an inner seal 23 and an outer seal 24 (seal). The inner seal 23 is joined to the first seal portion 21 so as to surround the first seal portion 21 from the outside. The inner seal 23 is welded to the outer surface of the first seal portion 21 by heat, for example, during injection molding. The inner seal 23 is in contact with the side surface 11c and is provided on the side surface 11c. The inner seal 23 covers the entire side surface 11c in the first direction D1. The first direction of the inner seal 23 D1 The length of the inner seal 23 is equal to the length of the side surface 11c in the first direction D1. The inner seal 23 is provided in a cylindrical shape so as to cover the entire periphery of the electrode stack 11 when viewed in the first direction D1.

[0039] The outer seal 24 is joined to the inner seal 23 so as to surround the inner seal 23 from the outside. The outer seal 24 has a side surface portion 25, a first protruding portion 26, and a second protruding portion 27. The side surface portion 25, the first protruding portion 26, and the second protruding portion 27 are integrally formed by, for example, injection molding. The side surface portion 25 is provided on the side surface 11c, sandwiching the inner seal 23 therebetween. The side surface portion 25 is welded to the outer surface of the inner seal 23 by, for example, heat during injection molding. Furthermore, the outer seal 24 is provided in a cylindrical shape so as to cover the entire circumference of the electrode stack 11 when viewed from the first direction D1.

[0040] The first overhanging portion 26 overhangs the first end surface 11a from one end of the side surface portion 25 in the first direction D1. The second overhanging portion 27 overhangs the second end surface 11b from the other end of the side surface portion 25 in the first direction D1. That is, the first overhanging portion 26 is a portion that extends inward from the inner peripheral edge of the side surface portion 25 when viewed from the first direction D1. Similarly, the second overhanging portion 27 is a portion that extends inward from the inner peripheral edge of the side surface portion 25 when viewed from the first direction D1. When viewed from the first direction D1, the inner edge 26d of the first overhanging portion 26 and the inner edge 27d of the second overhanging portion 27 are located outward from the inner edge 21d of the first seal portion 21. The first overhanging portion 26 and the second overhanging portion 27 have the same thickness (length in the first direction D1). The first protruding portion 26 and the second protruding portion 27 are provided continuously over all sides of the electrode plate 15. The first protruding portion 26 and the second protruding portion 27 are formed in the shape of a rectangular frame when viewed from the first direction D1.

[0041] The first seal portion 21 and the second seal portion 12 seal between adjacent bipolar electrodes 14 in the first direction D1, between the negative electrode terminal electrode 18 and the bipolar electrode 14, and between the positive electrode terminal electrode 19 and the bipolar electrode 14, respectively. This creates airtightly separated internal spaces V between the bipolar electrodes 14, between the negative electrode terminal electrode 18 and the bipolar electrode 14, and between the positive electrode terminal electrode 19 and the bipolar electrode 14. That is, the first seal portion 21 and the second seal portion 12 form the internal spaces V between the electrodes and seal the internal spaces V. An electrolyte (not shown) such as an alkaline solution, such as a potassium hydroxide aqueous solution, is contained in the internal spaces V. At least a portion of the electrolyte may be impregnated into the separator 13, the positive electrode active material layer 16, and the negative electrode active material layer 17.

[0042] The first seal portion 21 and the second seal portion 12 may be made of, for example, an insulating resin such as polypropylene (PP), polyphenylene sulfide (PPS), or modified polyphenylene ether (modified PPE).

[0043] 1 to 4, the second seal portion 12 includes a pair of outer peripheral surfaces 12s and a pair of outer peripheral surfaces 12r connecting the outer peripheral surfaces 12s. The outer peripheral surfaces 12s and 12r are surfaces extending along the first direction D1. Here, the outer peripheral surface 12s is a surface that intersects (is perpendicular to) the third direction D3, and the outer peripheral surface 12r is a surface that intersects (is perpendicular to) the second direction D2. The length of the outer peripheral surface 12s in the second direction D2 is longer than the length of the outer peripheral surface 12r in the third direction D3. In the conductive plate 5 described above, the flow paths 5a extend along the third direction D3 and open to a pair of surfaces of the conductive plate 5 that intersect with the third direction D3.

[0044] Therefore, the gaps on the outer peripheral surfaces 12s side of the second seal portions 12 of adjacent energy storage modules 4 are used for introducing and discharging the refrigerant into and from the flow paths 5a (the refrigerant passes through them). On the other hand, the gaps on the outer peripheral surfaces 12r side of the second seal portions 12 of adjacent energy storage modules 4 are not used for introducing and discharging the refrigerant into and from the flow paths 5a. For this reason, in the module stack 2, the gaps on the outer peripheral surfaces 12s side of the second seal portions 12 of adjacent energy storage modules 4 are open, and the gaps on the outer peripheral surfaces 12r side are filled with sealing material E.

[0045] Here, the energy storage module 4 may include a pair of metal plates 50. In this embodiment, the metal plates 50 are provided at one end (the end on the negative terminal electrode 18 side) and the other end (the end on the positive terminal electrode 19 side) of the electrode stack 11 in the first direction D1. One of the pair of metal plates 50 contacts the first surface 15a of the electrode plate 15 of the negative terminal electrode 18 and the conductive plate 5. The other of the pair of metal plates 50 contacts the second surface 15b of the electrode plate 15 of the positive terminal electrode 19 and another conductive plate 5. In this way, in the energy storage module 4, the metal plates 50 are provided further outside the negative terminal electrode 18 and the positive terminal electrode 19. The metal plate 50 arranged at one end of the energy storage module 4 in the first direction D1 contacts the negative terminal electrode 18 and forms the negative terminal surface of the energy storage module 4. Furthermore, the metal plate 50 disposed at the other end of the power storage module 4 in the first direction D1 is in contact with the positive terminal electrode 19 and constitutes the positive terminal surface of the power storage module 4.

[0046] The peripheral edge of one of the pair of metal plates 50 is sandwiched between a first portion 21a of a first seal portion 21 provided on the electrode plate 15 of the negative terminal electrode 18 and another first portion 21a provided on the opposite side of the first portion 21a. The pair of first portions 21a are joined (e.g., welded) together by a third portion 21c. The peripheral edge of the other of the pair of metal plates 50 is sandwiched between a first portion 21a of a first seal portion 21 provided on the electrode plate 15 of the positive terminal electrode 19 and another first portion 21a provided on the opposite side of the first portion 21a. The pair of first portions 21a are also joined (e.g., welded) together by a third portion 21c. The metal plate 50 is an uncoated foil with no active material layers formed on either side. The same metal foil (uncoated foil) as the electrode plate 15 can be used for the metal plate 50.

[0047] Next, the second seal portion 12 will be described in detail. Fig. 5 is a partial perspective view of the rib and its periphery as viewed from above in the first direction D1. Fig. 6 is a partial perspective view of the rib and its periphery as viewed from below in the first direction D1. Fig. 7 is a plan view showing an enlarged view of the rib and its periphery. Fig. 8 is a side view showing an enlarged view of the rib and its periphery. Fig. 9 is a cross-sectional view showing an enlarged view of the rib and its periphery. As shown in Figs. 4 to 9, the outer seal 24 has a canopy 60 and a rib 70. The canopy 60 and the rib 70 are formed integrally with the side surface portion 25, the first protruding portion 26, and the second protruding portion 27 by, for example, resin injection molding. In other words, the side surface portion 25, the first protruding portion 26, the second protruding portion 27, the canopy 60, and the rib 70 are formed as a single member by a single injection molding.

[0048] The eaves 60 function to suppress a phenomenon known as a liquid short circuit, in which liquid adhering near one terminal surface of the energy storage module 4 flows along the outer peripheral surface of the outer seal 24 to the other terminal surface of the energy storage module 4, causing a short circuit between the positive electrode terminal surface and the negative electrode terminal surface of the energy storage module 4. The liquid may be, for example, electrolyte leaking from inside the energy storage module 4 or condensed water from outside the energy storage module 4. As described above, the gaps on the outer peripheral surfaces 12r of the second seal portions 12 of adjacent energy storage modules 4 are filled with the sealing material E (see FIG. 1 ), so there is little need to provide the eaves 60 on the outer peripheral surfaces 12r of each energy storage module 4. For this reason, in the energy storage module 4, the eaves 60 are provided only on the outer peripheral surface 12s of the outer peripheral surfaces 12s, 12r of the second seal portion 12. The eaves 60 are elongated, plate-shaped protrusions that are integrated with the side surface portion 25 and extend in the second direction D2.

[0049] The eaves 60 extend outward from the electrode stack 11 from the outer surface of the side surface portion 25 that constitutes the outer peripheral surface 12s. The eaves 60 extend in the second direction D2 along the outer peripheral surface 12s. The side surface portion 25 has a connection portion 25a, a first side surface portion 25b, and a second side surface portion 25c. The eaves 60 is connected to the connection portion 25a. The connection portion 25a is provided in the center of the side surface 11c in the first direction D1. The first side surface portion 25b is located between the connection portion 25a and the first overhanging portion 26 and connects the connection portion 25a to the first overhanging portion 26. The second side surface portion 25c is located between the connection portion 25a and the second overhanging portion 27 and connects the connection portion 25a to the second overhanging portion 27.

[0050] In the direction perpendicular to the side surface 11c (third direction D3), the thickness t2 of the second side surface portion 25c is thicker than the thickness t1 of the first side surface portion 25b (t2>t1). In this embodiment, the thickness t1 of the first side surface portion 25b is constant throughout the first side surface portion 25b in the second direction D2, but it does not have to be constant. Furthermore, the thickness t2 of the second side surface portion 25c is constant throughout the second side surface portion 25c in the second direction D2, but it does not have to be constant. When the thickness t1 of the first side surface portion 25b and the thickness t2 of the second side surface portion 25c are not constant, it is sufficient that at least the average value of the thickness t2 of the second side surface portion 25c is greater than the average value of the thickness t1 of the first side surface portion 25b. For example, the minimum value of the thickness t2 of the second side surface portion 25c may be equal to or greater than the maximum value of the thickness t1 of the first side surface portion 25b.

[0051] The second side surface portion 25c has a thick portion 25d at a position facing the rib 70 across the eave 60 in the first direction D1. The thick portion 25d is a portion that bulges outward from the electrode stack 11. The thick portion 25d is provided in contact with the eave 60.

[0052] The canopy 60 includes a base end portion 61, an inclined portion 62, and a tip end portion 63. The base end portion 61 is connected to the side surface portion 25. The base end portion 61 protrudes from the outer peripheral surface 12s in a direction perpendicular to the outer peripheral surface 12s (third direction D3). The upper surface 61s of the base end portion 61 is a flat surface (horizontal surface) extending along the second direction D2 and the third direction D3. The upper surface 61s is a surface facing upward in the first direction D1. The upper surface 61s is adjacent to the first side surface portion 25b and is continuous with the first side surface portion 25b.

[0053] The inclined portion 62 connects the base end portion 61 and the tip end portion 63. The inclined portion 62 is inclined with respect to the third direction D3 so that the distance from the outer peripheral surface 12s gradually increases as it moves downward (vertically downward) in the first direction D1. As a result, the upper surface 62s of the inclined portion 62 is an inclined surface that is inclined so as to move away from the outer peripheral surface 12s as it moves downward in the first direction D1. The upper surface 62s is a surface that faces upward in the first direction D1. The upper surface 62s is adjacent to the upper surface 61s and is continuous with the upper surface 61s.

[0054] The tip portion 63 extends from the tip of the inclined portion 62 so as to be inclined with respect to the third direction D3 at an angle greater than the angle at which the inclined portion 62 is inclined with respect to the third direction D3. This improves the drainage of liquid flowing along the canopy 60. Note that the tip portion 63 may extend downward substantially perpendicularly from the tip of the inclined portion 62 so that the distance from the outer peripheral surface 12s is substantially constant regardless of the position in the first direction D1. The tip (lower end) of the tip portion 63 is set at a position so as not to protrude from the side surface portion 25 and the second protruding portion 27 in the first direction D1.

[0055] The ribs 70 are provided on the eaves 60 to reinforce the eaves 60. The multiple ribs 70 are provided at predetermined intervals along the extension direction of the eaves 60 (second direction D2). The ribs 70 have a plate-shaped main body portion 71 and a pillar portion 72. The main body portion 71 connects the eaves 60 and the first side surface portion 25b. The main body portion 71 protrudes upward in the first direction D1 from the upper surface 61s of the base end portion 61 and the upper surface 62s of the inclined portion 62. The main body portion 71 is provided across the entire upper surface 61s and the upper surface 62s in a direction perpendicular to the side surface 11c (third direction D3). The main body portion 71 is connected to the first side surface portion 25b at a position spaced apart from the first protrusion portion 26 in the first direction D1.

[0056] The main body 71 has a first main body portion 73 connected to the first side surface portion 25b and a second main body portion 74 connected to the pillar portion 72. The first main body portion 73 is provided on the upper surface 61s. The first main body portion 73 has a rectangular shape when viewed from the second direction D2. The first main body portion 73 is spaced a distance d1 (d1>0) from the first protrusion 26 in the first direction D1. The second main body portion 74 is provided on the upper surface 62s. The second main body portions 74 are connected to both sides of the pillar portion 72 in the third direction D3, and sandwich the pillar portion 72 in the third direction D3.

[0057] The distance d1 by which the first main body portion 73 is separated from the first protruding portion 26 in the stacking direction is longer than the distance d2 by which the second main body portion 74 is separated from the first protruding portion 26 in the stacking direction (d1>d2). As a result, a step is formed between the first main body portion 73 and the second main body portion 74. The step is an inclined surface. It can also be said that a notch is provided in the portion of the main body portion 71 adjacent to the first side surface portion 25b. Note that in FIG. 5, a notch 74a is also provided in the upper end of the second main body portion 74 on the opposite side to the first main body portion 73. However, this notch 74a is a structure provided, for example, due to the characteristics of the manufacturing equipment, and is not an essential structure for the main body portion 71.

[0058] The pillar portion 72 protrudes upward in the first direction D1 from the upper surface 62s of the inclined portion 62. The tip (upper end) of the pillar portion 72 is set at a position that does not protrude from the first protruding portion 26 in the first direction D1. The pillar portion 72 has a cylindrical shape with a circular cross section. The pillar portion 72 is provided at the center of the upper surface 62s in the third direction D3. The pillar portion 72 divides the second main body portion 74 of the main body portion 71 in a direction (third direction D3) perpendicular to the side surface 11c. The pillar portion 72 is thicker than the main body portion 71 in a direction (second direction D2) perpendicular to the stacking direction (first direction D1) and parallel to the side surface 11c. The pillar portion 72 protrudes upward more than the main body portion 71 in the first direction D1.

[0059] On the upper surface of the first overhanging portion 26, a protrusion 26a protruding upward is provided at a position corresponding to the rib 70. On the lower surface of the second overhanging portion 27, a protrusion 27a protruding downward is provided at a position corresponding to the rib 70. In the energy storage device 1, energy storage modules 4 adjacent in the first direction D1 are arranged so that the protrusions 26a and the protrusions 27a face each other in the first direction D1. Even if the energy storage modules 4 expand, a gap between the energy storage modules 4 can be secured by bringing the protrusions 26a and the protrusions 27a into contact with each other.

[0060] Next, a method for forming the second seal portion 12 will be described. Figure 10 is a cross-sectional view for explaining the inner seal forming step. Figure 11 is a cross-sectional view for explaining the outer seal forming step.

[0061] 10, in the process of forming the inner seal 23 (see FIG. 9), a pair of molds 55, 56 configured to be able to move toward and away from each other in the first direction D1 is used to form the inner seal 23 along the side surface 11c. When the pair of molds 55, 56 are in contact with each other (closed mold state), a space for arranging the electrode stack 11 and a space for forming the inner seal 23 are provided inside the pair of molds 55, 56.

[0062] The electrode stack 11 is arranged so that the entire first end face 11a and the entire second end face 11b are pressed against the molds 55, 56. A compressive force in the first direction D1 is applied to the electrode stack 11 by the pair of molds 55, 56. In this state, the resin that constitutes the inner seal 23 is injected in a molten state into the pair of molds 55, 56 from, for example, an injection port H1 (a resin injection gate) that is provided so as to face the side surface 11c. As a result, the third portion 21 c( See FIG. 3) is covered by an inner seal 23.

[0063] 11, in the process of forming the outer seal 24 (see FIG. 9), a pair of molds 57, 58 configured to be movable toward and away from each other in the first direction D1 is used to form the side portion 25 along the inner seal 23, and also form a first protruding portion 26 that protrudes from the side portion 25 onto the first end face 11a and a second protruding portion 27 that protrudes from the side portion 25 onto the second end face 11b. When the pair of molds 57, 58 are in contact with each other (mold closed state), a space for arranging the electrode stack 11 with the inner seal 23 provided thereon and a space for forming the outer seal 24 are provided inside the pair of molds 57, 58.

[0064] The resin constituting the outer seal 24 is injected in a molten state into the pair of molds 57, 58, for example, from an injection port H2 (resin injection gate) provided in the forming space of the column portion 72. As a result, the inner seal 23 is covered with the outer seal 24. Because the outer edge portion of the electrode stack 11 and the inner seal 23 are not in contact with the pair of molds 57, 58, there is a risk that the outer edge portion of the electrode stack 11 and the inner seal 23 may be deformed by the resin injection pressure. This may cause the outer edge portion of the electrode stack 11 and the inner seal 23 to be misaligned in the first direction D1, resulting in uneven thickness between the first protruding portion 26 and the second protruding portion 27. In the energy storage module 4, unevenness in the amount of resin flowing between the first protruding portion 26 and the second protruding portion 27 is unlikely to occur. Therefore, the outer edge portion of the electrode stack 11 and the inner seal 23 are prevented from being misaligned in the first direction D1 within the pair of molds 57, 58. The reason for this is explained below.

[0065] The rib 70 is connected to the eave 60 and the first side surface portion 25b of the side surface portion 25. When injection molding is performed using the rib 70 as a resin inlet, the resin can travel from the rib 70 to the first side surface portion 25b via the eave 60, as well as via a direct path between the rib 70 and the first side surface portion 25b without passing through the eave 60. In contrast, the resin can only travel from the rib 70 to the second side surface portion 25c of the side surface portion 25 via the eave 60. Therefore, the resin injected from the rib 70 is more likely to flow into the first side surface portion 25b than into the second side surface portion 25c.

[0066] The thickness t2 of the second side surface portion 25c is greater than the thickness t1 of the first side surface portion 25b (t2>t1). That is, the flow path area in the resin flow direction in the second side surface portion 25c is greater than the flow path area in the resin flow direction in the first side surface portion 25b. Therefore, the resin flows more easily in the second side surface portion 25c than in the first side surface portion 25b. In contrast, as described above, the resin flows more easily into the first side surface portion 25b than into the second side surface portion 25c due to the rib 70 being connected thereto. Therefore, unevenness in the resin flowing into the portions forming the first protrusion 26 and the second protrusion 27 is unlikely to occur. As a result, the positions of the outer edge portion of the electrode stack 11 and the inner seal 23 are prevented from shifting in the first direction D1 within the pair of molds 57, 58.

[0067] Furthermore, the rib 70 has, in addition to the plate-shaped main body portion 71, a pillar portion 72 that protrudes from the eaves 60 at a distance from the first side surface portion 25b. Because the pillar portion 72 is thicker than the main body portion 71, if injection molding is performed using the pillar portion 72 as a resin inlet, the resin will easily flow into the eaves 60, and the flow of the resin from the eaves 60 into the side surface portion 25 can be promoted. In other words, because the main body portion 71 is thinner than the pillar portion 72, the amount of resin that flows through the main body portion 71 can be limited. This makes it possible to limit the amount of resin that flows directly from the rib 70 into the first side surface portion 25b without passing through the eaves 60. In other words, compared to when the pillar portion 72 is not provided on the rib 70, in this embodiment in which the pillar portion 72 is provided on the rib 70, the unevenness in the amount of resin that flows into the first side surface portion 25b and the second side surface portion 25c is suppressed. Therefore, the first side surface portion 25b The first extension located downstream of 26 and the second side part 25c The second overhang located downstream of 27 This makes it difficult for unevenness to occur in the flowing resin, and prevents the outer edge of the electrode stack 11 and the inner seal 23 from being misaligned in the first direction D1 within the pair of molds 57, 58. As a result, it is possible to prevent unevenness in the thickness between the first protruding portion 26 and the second protruding portion 27. As a result, the strength of the energy storage module 4 can be ensured.

[0068] The rib 70 has a pillar portion 72 that is thicker than the main body portion 71. This increases the strength of the rib 70. Therefore, even if the main body portion 71 is made thin, the strength of the rib 70 can be maintained.

[0069] The second side surface portion 25c has a thick portion 25d at a position facing the rib 70 across the eave 60 in the first direction D1. This ensures that the second side surface portion 25c is thicker than the first side surface portion 25b near the rib 70 where the resin flows in. The thick portion 25d allows the average thickness of the second side surface portion 25c to be greater than the average thickness of the first side surface portion 25b, even if the thickness of the portion of the second side surface portion 25c other than the thick portion 25d is made equal to the thickness of the first side surface portion 25b.

[0070] The main body portion 71 is connected to the first side surface portion 25b at a position spaced apart from the first protrusion portion 26 in the first direction D1. That is, a predetermined separation distance (distance d1) is provided between the first protrusion portion 26 and the first main body portion 73 in the stacking direction. Overhang 26 The distance that the resin flows from the rib 70 to the first overhanging portion 26 is longer than when the first main body portion 73 is provided at the same position as the first overhanging portion 26. As a result, it is possible to further prevent uneven thickness between the first overhanging portion 26 and the second overhanging portion 27.

[0071] Although an example embodiment of the present disclosure has been described in detail above, the present disclosure is not limited to the above embodiment.

[0072] For example, in the above embodiment, the energy storage device 1 includes a plurality of energy storage modules 4 stacked along the first direction D1. However, the number of energy storage modules 4 in the energy storage device 1 is arbitrary, and may be, for example, one.

[0073] In the energy storage module 4, the rib 70 does not need to have the pillar portion 72. Even in this case, since the second side surface portion 25c is thicker than the first side surface portion 25b, it is possible to prevent uneven thickness between the first protruding portion 26 and the second protruding portion 27.

[0074] In the energy storage module 4, the second side surface portion 25c may have the same thickness as the first side surface portion 25b. Even in this case, by providing the rib 70 with the pillar portion 72 that is thicker than the main body portion 71, it is possible to prevent uneven thickness from occurring between the first overhanging portion 26 and the second overhanging portion 27.

[0075] Second side surface portion 25c does not have to have thick portion 25d. Even in this case, for example, as long as the minimum thickness of second side surface portion 25c is equal to or greater than the maximum thickness of first side surface portion 25b, the average thickness of second side surface portion 25c will be greater than the average thickness of first side surface portion 25b.

[0076] The cross section of the column portion 72 is not limited to a circular shape, but may be rectangular, elliptical, or the like. [Explanation of symbols]

[0077] 4...storage module, 11...electrode stack, 11a...first end face, 11b...second end face, 11c...side face, 24...outer seal (seal), 25...side face portion, 25a...connection portion, 25b...first side face portion, 25c...second side face portion, 25d...thick portion, 26...first protrusion portion, 27...second protrusion portion, 60...eaves, 70...rib, 71...main body portion, 72...column portion, d1, d2...distance.

Claims

1. an electrode stack including a plurality of stacked electrodes; a seal provided around the electrode stack to seal between the electrodes, the electrode stack has a first end face and a second end face in a stacking direction of the plurality of electrodes, and a side face extending in the stacking direction so as to connect the first end face and the second end face, The seal is a side surface portion provided on the side surface; a first protruding portion protruding from the side surface onto the first end surface; a second protruding portion protruding from the side surface onto the second end surface; an eave extending from the side surface portion to the outside of the electrode stack; a rib provided on the eaves, the side surface portion has a connection portion to which the eaves are connected, a first side surface portion located between the connection portion and the first overhang portion, and a second side surface portion located between the connection portion and the second overhang portion, the rib connects the eave and the first side surface portion, The second side surface portion is thicker than the first side surface portion in a direction perpendicular to the side surface. Energy storage module.

2. the second side surface portion has a thick portion at a position facing the rib across the eaves in the stacking direction, The energy storage module according to claim 1 .

3. The rib has a plate-shaped main body portion connecting the eave and the first side surface portion, and a column portion spaced from the side surface portion and protruding from the eave in the stacking direction, the column portion is thicker than the main body portion in a direction perpendicular to the stacking direction and parallel to the side surface; The energy storage module according to claim 1 or 2.

4. the main body portion is connected to the first side surface portion at a position spaced apart from the first protruding portion in the stacking direction; The energy storage module according to claim 3 .

5. the main body portion has a first main body portion connected to the first side surface portion and a second main body portion connected to the column portion, a distance by which the first main body portion is spaced from the first protruding portion in the stacking direction is longer than a distance by which the second main body portion is spaced from the first protruding portion in the stacking direction; The energy storage module according to claim 4 .

6. an electrode stack including a plurality of electrodes stacked along a stacking direction; a seal provided around the electrode stack to seal between the electrodes, the electrode stack has a first end surface and a second end surface in the stacking direction, and a side surface extending in the stacking direction so as to connect the first end surface and the second end surface, The seal is a side surface portion provided on the side surface; a first protruding portion protruding from the side surface onto the first end surface; a second protruding portion protruding from the side surface onto the second end surface; an eave extending from the side surface portion to the outside of the electrode stack; a rib provided on the eaves, the side surface portion has a connection portion to which the eaves are connected, a first side surface portion located between the connection portion and the first overhang portion, and a second side surface portion located between the connection portion and the second overhang portion, the rib has a plate-shaped main body portion connecting the eave and the first side surface portion, and a column portion spaced from the first side surface portion and protruding from the eave in the stacking direction, the column portion is thicker than the main body portion in a direction perpendicular to the stacking direction and parallel to the side surface; Energy storage module.

7. the main body portion is connected to the first side surface portion at a position spaced apart from the first protruding portion in the stacking direction; The electricity storage module according to claim 6 .

8. the main body portion has a first main body portion connected to the first side surface portion and a second main body portion connected to the column portion, a distance by which the first main body portion is spaced from the first protruding portion in the stacking direction is longer than a distance by which the second main body portion is spaced from the first protruding portion in the stacking direction; The electricity storage module according to claim 7 .

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