Energy 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 a power storage module.

Background Art

[0002] There is known a power storage module including a seal including a side portion provided on a side surface of an electrode laminate and a pair of protruding portions protruding from the side portion to a pair of end surfaces of the electrode laminate (see, for example, Patent Document 1). The power storage unit described in Patent Document 1 includes a seal portion and a eaves portion formed in a long wall portion of the seal portion. The eaves portion includes an inclined portion having 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 accumulated in a gap between certain power storage units drips from the gap onto the eaves portion and moves on the inclined surface of the eaves portion, thereby being separated from the gap between other power storage units in the horizontal direction. As a result, it is intended to prevent the liquid from entering the gap between other power storage units. As a result, a short circuit (liquid contact) due to the liquid can be suppressed.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] When the seal portion of the power storage unit described in Patent Document 1 is formed by injection molding of resin, unevenness in wall thickness may occur between the pair of protruding portions. If there is unevenness in wall thickness between the pair of protruding portions, the strength of the power storage module may not be ensured.

[0005] An object of the present disclosure is to provide a power storage module capable of ensuring strength.

Means for Solving the Problems

[0006] An energy storage module according to one aspect of the present disclosure comprises an electrode stack including a plurality of stacked electrodes, and a seal provided around the electrode stack to seal the spaces 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 surface extending in the stacking direction to connect the first end face and the second end face, the seal has a side portion provided on the side surface, a first overhang extending from the side portion onto the first end face, a second overhang extending from the side portion onto the second end face, a canopy extending outward from the side portion of the electrode stack, and ribs provided on the canopy, wherein the side portion has a connecting portion to which the canopy is connected, a first side portion located between the connecting portion and the first overhang, and a second side portion located between the connecting portion and the second overhang, the ribs connect the canopy and the first side portion, and in a direction perpendicular to the side surface, the second side portion is thicker than the first side portion.

[0007] In this energy storage module, the ribs are connected to the canopy and the first side portion of the side section. Therefore, when injection molding is performed using the rib formation space (hereinafter also 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 portion (hereinafter also simply referred to as the first side portion) includes a path that goes through the canopy formation space (hereinafter also simply referred to as the canopy), as well as a path that bypasses the canopy and goes directly between the rib and the first side portion. In contrast, the resin path from the rib to the formation space of the second side portion of the side section (hereinafter also simply referred to as the second side portion) only goes through the canopy. Therefore, the resin injected from the rib flows more easily into the first side portion than into the second side portion. The second side portion is thicker than the first side portion, so the resin flows more easily into the second side portion than into the first side portion. Therefore, unevenness is less likely to occur between the resin flowing into the formation space of the first protrusion located downstream of the first side portion (hereinafter also 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 portion (hereinafter also simply referred to as the second protrusion). As a result, unevenness in wall thickness between the first and second protrusions can be suppressed. Thus, the strength of the energy storage module can be ensured.

[0008] The second side portion may have a thickened section in the stacking direction, facing the rib across the overhang.

[0009] Each rib has a plate-shaped main body that connects the eaves and the first side portion, and a column portion that is separated from the side portion and protrudes from the eaves in the stacking direction. In a direction perpendicular to the stacking direction and parallel to the side portion, the column portion may be thicker than the main body.

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

[0011] The main body comprises a first main body portion connected to a first side portion and a second main body portion connected to a column portion. The distance at which the first main body portion is separated from the first overhang portion in the stacking direction may be longer than the distance at which the second main body portion is separated from the first overhang portion in the stacking direction.

[0012] A different embodiment of the present disclosure of an energy storage module comprises an electrode stack including a plurality of electrodes stacked along a stacking direction, and a seal provided around the electrode stack to seal the spaces between the electrodes, wherein the electrode stack has a first end face and a second end face in the stacking direction, and a side surface extending in the stacking direction to connect the first end face and the second end face, the seal has a side portion provided on the side surface, a first overhang extending from the side portion onto the first end face, a second overhang extending from the side portion onto the second end face, a canopy extending outward from the side portion onto the electrode stack, and ribs provided on the canopy, wherein the side portion has a connecting portion to which the canopy is connected, a first side portion located between the connecting portion and the first overhang, and a second side portion located between the connecting portion and the second overhang, the ribs connecting the canopy and the first side portion and having a plate-shaped main body portion and the first side portion minutes It has a column portion that is separated from the eaves and protrudes in the stacking direction from the eaves, and in a direction perpendicular to the stacking direction and parallel to the side surface, the column portion is thicker than the main body portion.

[0013] In this energy storage module, the ribs are connected to the canopy and the first side portion of the side section. Therefore, when injection molding using the ribs as resin inlet ports, the resin path from the ribs to the first side portion includes a path via the canopy and a direct path between the ribs and the first side portion that bypasses the canopy. In contrast, the resin path from the ribs to the second side portion of the side section only includes a path via the canopy. Consequently, the resin injected from the ribs flows more easily into the first side portion than into the second side portion. The ribs have a plate-like main body and a column portion that is separated from the first side portion and protrudes from the canopy. Since the column portion is thicker than the main body, if injection molding is performed using the space formed by the column portion (hereinafter simply referred to as the column portion) as the resin inlet, the resin flows more easily into the canopy. This prevents the resin from flowing directly from the ribs to the first side portion without passing through the canopy. In other words, compared to the case where the column portion has the same thickness as the main body, the amount of resin flowing into the first and second side portions is less likely to be uneven. Therefore, the amount of resin flowing into the first protrusion located downstream of the first side portion and the second protrusion located downstream of the second side portion is less likely to be uneven. As a result, it is possible to suppress unevenness in wall thickness between the first and second protrusions. In this way, the strength of the energy storage module can be ensured.

[0014] In the energy storage module according to the above-described alternative embodiment, the main body may be connected to the first side portion at a position separated from the first protruding portion in the stacking direction.

[0015] In the energy storage module according to the above-described alternative embodiment, the main body portion comprises a first main body portion connected to a first side portion and a second main body portion connected to a column portion, and the distance at which the first main body portion is separated from the first protruding portion in the stacking direction may be longer than the distance at which the second main body portion is separated from the first protruding portion in the stacking direction. [Effects of the Invention]

[0016] According to this disclosure, it is possible to provide an energy storage module that can ensure strength. [Brief explanation of the drawing]

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

MODE FOR CARRYING OUT THE INVENTION

[0018] Hereinafter, an embodiment of a power storage device will be described with reference to the drawings. In the description of each figure, the same or corresponding elements are denoted by the same reference numerals, and redundant descriptions may be omitted. In addition, each figure illustrates a rectangular coordinate system constituted by 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 intersecting each other.

[0019] Figure 1 is a schematic cross-sectional view showing a cross-section of a power storage device according to one embodiment, including the first and second directions. Figure 2 is a schematic cross-sectional view showing a cross-section of a power storage device according to one embodiment, including the first and third directions. The power storage device 1 shown in Figures 1 and 2 can be used, for example, as a battery for various vehicles such as forklifts, hybrid vehicles, and electric vehicles. The power storage device 1 comprises a module stack 2 including a plurality of power storage modules 4 stacked along the 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 (in this case, three) of energy storage modules 4 and a plurality (in this case, two) of conductive plates 5. The energy storage module 4 is, for example, a bipolar battery and has a rectangular shape when viewed from the first direction D1. More specifically, the energy storage module 4 has a rectangular shape with a long side and a short side when viewed from the first direction D1. The energy storage module 4 is, for example, a secondary battery such as a nickel-metal hydride battery or a lithium-ion battery, or an electric double-layer capacitor. 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 energy storage modules 4 along the first direction D1. This electrically connects multiple energy storage modules 4 via the conductive plate 5. More specifically, each energy storage module 4 has a positive terminal surface on one end face in the first direction D1 and a negative terminal surface on the other end face in the first direction D1, and multiple energy storage modules 4 stacked via the conductive plate 5 are connected in series. A current collector plate 6 with a positive terminal 6a is positioned on the outside of an energy storage module 4 located at one end of the module stack 2 in the first direction D1 and is electrically connected to that energy storage module 4. Similarly, a current collector plate 7 with a negative terminal 7a is positioned on the outside of an energy storage module 4 located at the other end of the module stack 2 in the first direction D1 and is electrically connected to that energy storage module 4. Charging and discharging of the energy storage device 1 is performed using these positive terminal 6a and negative terminal 7a.

[0022] Multiple flow channels 5a are provided inside the conductive plate 5 for circulating a coolant such as air. The flow channels 5a extend in directions (in this case, the third direction D3) that intersect (are perpendicular to) the first direction D1 and the direction in which the positive terminal 6a and negative terminal 7a are drawn out. In addition to functioning as a connecting member that electrically connects the energy storage modules 4 together, the conductive plate 5 also functions as a heat dissipation member that dissipates heat generated in the energy storage modules 4 by circulating the coolant through these flow channels 5a.

[0023] The restraining member 3 includes a pair of restraining plates 8 that sandwich the module stack 2 in the stacking direction, a plurality of fasteners 9 such as bolts that connect the restraining plates 8 by fastening them together, and a support column 10 that houses the main body of the fasteners 9 (for example, the shaft of a bolt). The restraining plate 8 is a rectangular metal plate having an area slightly larger than the area of ​​the energy storage module 4 and conductive plate 5 as viewed from the first direction. The restraining plate 8 is rectangular in shape with a long side and a short side as viewed from the first direction D1. A plate-shaped insulating member F is provided on the inner surface of the restraining plate 8 (the surface facing the module stack 2). That is, a current collector plate 6 or current collector plate 7 and the insulating member F are interposed between the module stack 2 and the restraining plate 8. This provides insulation between the restraining plate 8 and the module stack 2 (specifically, the current collector plates 6 and 7).

[0024] An insertion hole 8a is provided on the edge of one restraint plate 8 at a position outside the module stack 2 when viewed from the first direction D1, and a screw hole 8b is provided on the edge of the other restraint plate 8 at a position opposite to the insertion hole 8a. The fastener 9 is passed through the insertion hole 8a of one restraint plate 8 towards the screw hole 8b of the other restraint plate 8 and screwed into the screw hole 8b of the other restraint plate 8. As a result, the energy storage module 4 and the conductive plate 5 are sandwiched by the restraint plates 8 and unitized as a module stack 2, and a restraining load is applied to the module stack 2 along the first direction.

[0025] Thus, the fastener 9 is positioned on the outside of the module stack 2, extends along the first direction D1, and restrains the module stack 2 by fastening a pair of restraint plates 8 together along the first direction D1. The support column 10 is interposed between the pair of restraint plates 8 and extends along the first direction D1 together with the fastener 9. The support column 10 defines the restraining force on the module stack 2 by defining the distance between the pair of restraint plates 8 in the first direction D1.

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

[0027] Figure 3 is a schematic cross-sectional view showing the energy storage module shown in Figures 1 and 2. Figure 4 is a perspective view showing the energy storage module shown in Figures 1 to 3. As shown in Figures 3 and 4, the energy storage module 4 comprises an electrode stack 11 and a second resin seal portion 12 that seals the electrode stack 11. The electrode stack 11 includes a plurality of electrodes (a plurality of bipolar electrodes 14, a negative terminal electrode 18, and a positive terminal electrode 19) stacked along a first direction D1 via a separator 13. 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 with a first surface 15a and a second surface 15b opposite to 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 in the first direction D1, separated by a separator 13. 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 in the first direction D1, separated by a separator 13.

[0029] The negative electrode terminal electrode 18 includes an electrode plate 15 and a negative electrode active material layer 17 provided on the second surface 15b of the electrode plate 15. The first surface 15a of the electrode plate 15 of the negative electrode terminal electrode 18 does not have an active material layer. The negative electrode terminal electrode 18 is positioned at one end of the electrode stack 11 in the first direction D1 such that its second surface 15b faces the inside of the electrode stack 11 (towards the center 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 of the first direction D1 via a separator 13.

[0030] The positive electrode terminal electrode 19 includes an electrode plate 15 and a positive electrode active material layer 16 provided on the first surface 15a of the electrode plate 15. The second surface 15b of the electrode plate 15 of the positive electrode terminal electrode 19 does not have an active material layer. The positive electrode terminal electrode 19 is positioned at the other end of the electrode stack 11 in the first direction D1 such that its first surface 15a is on the inside of the electrode stack 11. The positive electrode active material layer 16 of the positive electrode terminal electrode 19 faces the negative electrode active material layer 17 of the bipolar electrode 14 at the other end of the first direction D1, via a separator 13.

[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, which will be described later. The second surface 15b of the electrode plate 15 of the positive terminal electrode 19 is also 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, which will be described later.

[0032] The electrode plate 15 is made of a metal such as nickel or nickel-plated steel. For example, the electrode plate 15 is a rectangular metal foil made of nickel. The peripheral edge 15c of the electrode plate 15 (the peripheral edge of the bipolar electrode 14, the negative electrode terminal electrode 18, and the positive electrode terminal electrode 19) is rectangular in shape and is a region where the positive electrode active material layer 16 and the negative electrode active material layer 17 are not formed. Examples of positive electrode active materials that constitute the positive electrode active material layer 16 include nickel hydroxide. Examples of negative electrode active materials that constitute the negative electrode active material layer 17 include hydrogen storage alloys.

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

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

[0035] The third portion 21c has a rectangular cylindrical shape extending along the first direction D1 and is formed by joining and integrating a plurality of first portions 21a and a plurality of second portions 21b. The first portions 21a and the second portions 21b can be formed, for example, by folding a single sheet-like member. In this case, the third portion 21c is a welded end formed, for example, by welding together the folded portions (the outer ends of the first portions 21a and the second portions 21b) of the sheet-like members aligned in the first direction D1. The third portion 21c does not necessarily need 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 laminate 11 has a first end face 11a and a second end face 11b in a first direction D1, and a side surface 11c extending in the first direction D1 so as to connect the first end face 11a and the second end face 11b. The first end face 11a is composed of 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 composed of 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 a first seal portion 21 provided on the metal plate 50. The side surface 11c is composed of the outer surface of the third portion 21c.

[0037] The second seal portion 12 is formed in an overall rectangular cylindrical shape, for example, from an insulating resin. 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 resin injection molding and extends along 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 it from the outside. The inner seal 23 is welded to the outer surface of the first seal portion 21 by heat during injection molding, for example. The inner seal 23 is in contact with the side surface 11c and is provided on the side surface 11c. In the first direction D1, the inner seal 23 covers the entire side surface 11c. D1 The length of the side surface 11c is equivalent to the length of the first direction D1. The inner seal 23 is also provided in a cylindrical shape so as to cover the entire circumference of the electrode stack 11 when viewed from the first direction D1.

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

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

[0041] The first seal portion 21 and the second seal portion 12 seal the spaces between adjacent bipolar electrodes 14 in the first direction D1, between the negative terminal electrode 18 and the bipolar electrode 14, and between the positive terminal electrode 19 and the bipolar electrode 14, respectively. As a result, airtightly partitioned internal spaces V are formed between the bipolar electrodes 14, between the negative terminal electrode 18 and the bipolar electrode 14, and between the positive terminal electrode 19 and the bipolar electrode 14. In other words, the first seal portion 21 and the second seal portion 12 are for forming the internal spaces V between the electrodes and sealing the internal spaces V. This internal space V contains an electrolyte (not shown) consisting of an alkaline solution such as an aqueous potassium hydroxide solution. At least a portion of the electrolyte can be impregnated into the separator 13, the positive electrode active material layer 16, and the negative electrode active material layer 17.

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

[0043] As shown in Figures 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 two outer peripheral surfaces 12s. The outer peripheral surfaces 12s and 12r are surfaces that extend 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. Also, 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 path 5a extends along the third direction D3 and opens to a pair of surfaces of the conductive plate 5 that intersect the third direction D3.

[0044] Therefore, the gap on the outer peripheral surface 12s side of the second seal portion 12 of adjacent energy storage modules 4 is used for the introduction and discharge of refrigerant to the flow path 5a (the refrigerant passes through it). On the other hand, the gap on the outer peripheral surface 12r side of the second seal portion 12 of adjacent energy storage modules 4 is not used for the introduction and discharge of refrigerant to the flow path 5a. For this reason, in the module stack 2, the gap on the outer peripheral surface 12s side of the second seal portion 12 of adjacent energy storage modules 4 is open, and the gap on the outer peripheral surface 12r side is 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 located at one end of the energy storage module 4 in the first direction D1 is in contact with the negative terminal electrode 18 and constitutes the negative terminal surface of the energy storage module 4. Furthermore, the metal plate 50 positioned at the other end of the energy 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 energy storage module 4.

[0046] One peripheral edge 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 electrode terminal electrode 18 and another first portion 21a provided on the opposite side of the first portion 21a. These pair of first portions 21a are joined (e.g., welded) together by a third portion 21c. The other peripheral edge 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 electrode terminal electrode 19 and another first portion 21a provided on the opposite side of the first portion 21a. These 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 layer formed on both sides. The same metal foil (uncoated foil) as the electrode plate 15 can be used as the metal plate 50.

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

[0048] The canopy 60 has the function of suppressing a phenomenon known as a liquid junction, in which liquid adhering to the vicinity of one terminal surface of the energy storage module 4 flows along the outer surface of the outer seal 24 to the other terminal surface of the energy storage module 4, causing a short circuit between the positive and negative terminal surfaces of the energy storage module 4 via the liquid. The liquid is, for example, electrolyte leaked from inside the energy storage module 4 or condensation from outside the energy storage module 4. As described above, the gap on the outer surface 12r side of the second seal portion 12 of adjacent energy storage modules 4 is filled with sealing material E (see Figure 1), so there is little need to provide a canopy 60 on the outer surface 12r of each energy storage module 4. For this reason, in the energy storage module 4, the canopy 60 is provided only on the outer surface 12s of the outer surfaces 12s and 12r of the second seal portion 12. The canopy 60 is an elongated plate-shaped projection that is integrated with the side portion 25 and extends in the second direction D2.

[0049] The canopy 60 extends outward from the outer surface of the side portion 25 that constitutes the outer peripheral surface 12s to the electrode stack 11. The canopy 60 extends in a second direction D2 along the outer peripheral surface 12s. The side portion 25 has a connecting portion 25a, a first side portion 25b, and a second side portion 25c. The canopy 60 is connected to the connecting portion 25a. The connecting portion 25a is located in the center of the side portion 11c in the first direction D1. The first side portion 25b is located between the connecting portion 25a and the first overhang 26 and connects the connecting portion 25a and the first overhang 26. The second side portion 25c is located between the connecting portion 25a and the second overhang 27 and connects the connecting portion 25a and the second overhang 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 greater 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 over the entire second direction D2 of the first side surface portion 25b, but it does not have to be constant. Similarly, the thickness t2 of the second side surface portion 25c is constant over the entire second direction D2 of the second side surface portion 25c, but it does not have to be constant. If the thickness t1 of the first side surface portion 25b and the thickness t2 of the second side surface portion 25c are not constant, at least the average value of the thickness t2 of the second side surface portion 25c must be 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 greater than or equal to the maximum value of the thickness t1 of the first side surface portion 25b.

[0051] The second side portion 25c has a thickened portion 25d in the first direction D1, at a position facing the rib 70 with the overhang 60 in between. The thickened portion 25d is a raised portion toward the outside of the electrode stack 11. The thickened portion 25d is provided in contact with the overhang 60.

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

[0053] The inclined portion 62 connects the base portion 61 and the tip portion 63. The inclined portion 62 is inclined with respect to the third direction D3 such 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 moves away from the outer peripheral surface 12s as it moves downward in the first direction D1. The upper surface 62s is the surface facing 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 such that it is inclined with respect to the third direction D3 at a larger angle than the angle at which the inclined portion 62 is inclined with respect to the third direction D3. This improves the liquid drainage of liquid flowing down the canopy 60. The tip portion 63 may also extend substantially vertically downward from the tip of the inclined portion 62 such 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 in a position that does not protrude from the side portion 25 and the second overhang portion 27 in the first direction D1.

[0055] The ribs 70 are provided on the canopy 60 and reinforce it. Multiple ribs 70 are provided at predetermined intervals along the extending direction (second direction D2) of the canopy 60. The ribs 70 have a plate-shaped main body portion 71 and a column portion 72. The main body portion 71 connects the canopy 60 to the first side 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 over the entire upper surface 61s and 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 portion 25b at a position separated from the first overhang portion 26 in the first direction D1.

[0056] The main body portion 71 has a first main body portion 73 connected to the first side portion 25b and a second main body portion 74 connected to the column 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 separated from the first overhang portion 26 at a distance d1 (d1>0) in the first direction D1. The second main body portion 74 is provided on the upper surface 62s. The second main body portion 74 is connected to both sides of the column portion 72 in the third direction D3, sandwiching the column portion 72 in the third direction D3.

[0057] The distance d1 at 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 at 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. This step consists of 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 portion 25b. In Figure 5, a notch 74a is also provided at the upper end of the second main body portion 74 on the opposite side from the first main body portion 73, but this notch 74a is a structure provided for reasons such as the characteristics of the manufacturing equipment and is not an essential structure for the main body portion 71.

[0058] The column 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 column portion 72 is set to a position where it does not protrude from the first overhang portion 26 in the first direction D1. The column portion 72 has a cylindrical shape with a circular cross-section. The column portion 72 is located in the center of the upper surface 62s in the third direction D3. The column portion 72 divides the second main body portion 74 of the main body portion 71 in a direction perpendicular to the side surface 11c (third direction D3). The column portion 72 is thicker than the main body portion 71 in a direction perpendicular to the stacking direction (first direction D1) and parallel to the side surface 11c (second direction D2). The column portion 72 protrudes upward above the main body portion 71 in the first direction D1.

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

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

[0061] As shown in Figure 10, in the process of forming the inner seal 23 (see Figure 9), a pair of molds 55, 56 configured to move toward and away from each other in a first direction D1 are 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), the inside of the pair of molds 55, 56 is provided with a space for arranging the electrode laminate 11 and a space for forming the inner seal 23.

[0062] The electrode laminate 11 is positioned such that the entirety of the first end face 11a and the second end face 11b are pressed against the molds 55, 56. The electrode laminate 11 is subjected to a compressive force in the first direction D1 by the pair of molds 55, 56. In this state, the resin constituting the inner seal 23 is injected in a molten state into the pair of molds 55, 56 from, for example, an injection port H1 (resin injection gate) provided facing the side surface 11c. As a result, the third portion 21 c( (See Figure 3) is covered by the internal seal 23.

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

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

[0065] The rib 70 is connected to the canopy 60 and the first side portion 25b of the side portion 25. When injection molding is performed using the rib 70 as the resin injection port, the resin path from the rib 70 to the first side portion 25b includes a path via the canopy 60, as well as a direct path between the rib 70 and the first side portion 25b that bypasses the canopy 60. In contrast, the resin path from the rib 70 to the second side portion 25c of the side portion 25 only includes a path via the canopy 60. Therefore, the resin injected from the rib 70 flows more easily into the first side portion 25b than into the second side portion 25c.

[0066] The thickness t2 of the second side portion 25c is greater than the thickness t1 of the first side portion 25b (t2 > t1). In other words, the flow area in the resin flow direction in the second side portion 25c is larger than the flow area in the resin flow direction in the first side portion 25b. Therefore, resin flows more easily in the second side portion 25c than in the first side portion 25b. In contrast, as mentioned above, resin flows more easily into the first side portion 25b than into the second side portion 25c because the rib 70 is connected to it. Therefore, uneven distribution of resin flow into the portions forming the first protrusion 26 and the second protrusion 27 is less likely to occur. As a result, the displacement of the outer edge of the electrode laminate 11 and the inner seal 23 in the first direction D1 within the pair of molds 57 and 58 is suppressed.

[0067] Furthermore, in addition to the plate-shaped main body portion 71, the rib 70 has a column portion 72 that is separated from the first side portion 25b and protrudes from the canopy 60. Since the column portion 72 is thicker than the main body portion 71, if the column portion 72 is used as a resin injection port for injection molding, the resin can easily flow into the canopy 60, and the flow of resin from the canopy 60 to the side portion 25 can be promoted. In other words, since the main body portion 71 is thinner than the column portion 72, the amount of resin flowing through the main body portion 71 can be limited. This limits the amount of resin that flows directly from the rib 70 to the first side portion 25b without passing through the canopy 60. In other words, compared to the case where the rib 70 does not have a column portion 72, in this embodiment in which the rib 70 has a column portion 72, the uneven distribution of the amount of resin flowing into the first side portion 25b and the second side portion 25c is suppressed. 25b The first overhang located downstream 26 and the second side section 25c The second extension located downstream 27 This makes it less likely for unevenness to occur in the flowing resin, and prevents the outer edge of the electrode laminate 11 and the inner seal 23 from shifting in the first direction D1 within the pair of molds 57 and 58. As a result, it is possible to suppress unevenness in wall 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 column 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 thinner, the strength of the rib 70 can be maintained.

[0069] The second side portion 25c has a thickened portion 25d at a position facing the rib 70 across the canopy 60 in the first direction D1. Therefore, the second side portion 25c is reliably thicker than the first side portion 25b in the vicinity of the rib 70 into which the resin flows. With the thickened portion 25d, even if the thickness of the portion of the second side portion 25c other than the thickened portion 25d is made the same as the thickness of the first side portion 25b, the average thickness of the second side portion 25c can be made greater than the average thickness of the first side portion 25b.

[0070] The main body portion 71 is connected to the first side portion 25b at a position separated from the first protruding portion 26 in the first direction D1. That is, in the stacking direction, a predetermined separation distance (distance d1) is provided between the first protruding portion 26 and the first main body portion 73. Therefore, in the stacking direction, Overhang 26 Compared to the case where the first main body portion 73 and the rib 70 are located in the same position, the distance over which the resin flows from the rib 70 to the first protruding portion 26 is increased. As a result, it is possible to further suppress the occurrence of thickness unevenness between the first protruding portion 26 and the second protruding portion 27.

[0071] The above describes in detail one example of the form of this disclosure, but this disclosure is not limited to the above form.

[0072] For example, in the above embodiment, the energy storage device 1 had 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 a column portion 72. Even in this case, the second side portion 25c is thicker than the first side portion 25b, which helps to suppress unevenness in thickness between the first protruding portion 26 and the second protruding portion 27.

[0074] In the energy storage module 4, the second side portion 25c may have the same thickness as the first side portion 25b. Even in this case, by providing the rib 70 with a column portion 72 that is thicker than the main body portion 71, it is possible to suppress the occurrence of a thickness imbalance between the first protruding portion 26 and the second protruding portion 27.

[0075] The second side portion 25c does not necessarily have a thickened portion 25d. Even in this case, for example, if the minimum thickness of the second side portion 25c is greater than or equal to the maximum thickness of the first side portion 25b, the average thickness of the second side portion 25c will be greater than the average thickness of the first side portion 25b.

[0076] The column section 72 is not limited to a circular cross-section; it may also have a rectangular cross-section, an elliptical cross-section, or the like. [Explanation of Symbols]

[0077] 4... Energy storage module, 11... Electrode stack, 11a... First end face, 11b... Second end face, 11c... Side surface, 24... Outer seal (seal), 25... Side surface, 25a... Connection part, 25b... First side surface, 25c... Second side surface, 25d... Thickened part, 26... First protrusion, 27... Second protrusion, 60... Canopy, 70... Rib, 71... Main body, 72... Column, d1, d2... Distance.

Claims

1. An electrode stack containing multiple stacked electrodes, A seal is provided around the electrode stack to seal the space between the electrodes, 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 surface extending in the stacking direction so as to connect the first end face and the second end face, The seal mentioned above is A side portion provided on the aforementioned side surface, A first protruding portion extending from the side portion onto the first end surface, A second protruding portion extending from the side portion onto the second end surface, An overhang extending outward from the aforementioned side portion of the electrode stack, The canopy has ribs provided on it, The side portion has a connecting portion to which the canopy is connected, a first side portion located between the connecting portion and the first overhang, and a second side portion located between the connecting portion and the second overhang. The rib connects the canopy and the first side portion. In a direction perpendicular to the aforementioned side surface, the second side surface portion is thicker than the first side surface portion. Energy storage module.

2. The second side portion has a thickened portion at a position facing the rib with the overhang in the stacking direction. The energy storage module according to claim 1.

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

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

5. The main body portion comprises a first main body portion connected to the first side portion and a second main body portion connected to the column portion. The distance at which the first main body portion is separated from the first protruding portion in the stacking direction is longer than the distance at which the second main body portion is separated from the first protruding portion in the stacking direction. The energy storage module according to claim 4.

6. An electrode stack comprising multiple electrodes stacked along the stacking direction, A seal is provided around the electrode stack to seal the space between the electrodes, The electrode stack has a first end face and a second end face in the stacking direction, and a side surface extending in the stacking direction so as to connect the first end face and the second end face, The seal mentioned above is A side portion provided on the aforementioned side surface, A first protruding portion extending from the side portion onto the first end surface, A second protruding portion extending from the side portion onto the second end surface, An overhang extending outward from the aforementioned side portion of the electrode stack, The canopy has ribs provided on it, The side portion has a connecting portion to which the canopy is connected, a first side portion located between the connecting portion and the first overhang, and a second side portion located between the connecting portion and the second overhang. The rib has a plate-shaped main body that connects the canopy and the first side portion, and a column portion that is separated from the first side portion and protrudes from the canopy in the stacking direction. In a direction perpendicular to the stacking direction and parallel to the side surface, the column portion is thicker than the main body portion. Energy storage module.

7. The main body is connected to the first side portion at a position separated from the first protruding portion in the stacking direction. The energy storage module according to claim 6.

8. The main body portion comprises a first main body portion connected to the first side portion and a second main body portion connected to the column portion. The distance at which the first main body portion is separated from the first protruding portion in the stacking direction is longer than the distance at which the second main body portion is separated from the first protruding portion in the stacking direction. The energy storage module according to claim 7.

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