Energy storage device

Abstract

An energy storage device includes a plurality of stacked energy storage modules, and conductive plates and sealing members disposed between adjacent energy storage modules. Each of the plurality of energy storage modules has an electrode stack, an electrolyte, and a sealing body. The electrode stack includes a plurality of electrodes stacked along the stacking direction of the energy storage modules, separated by a separator. The electrolyte is contained in the internal space between adjacent electrodes. The sealing body surrounds the side of the electrode stack along the stacking direction and seals the internal space. The plurality of electrodes have a negative terminal electrode, a positive terminal electrode, and a plurality of bipolar electrodes stacked between the two. Each of the plurality of bipolar electrodes has an electrode plate, a positive electrode, and a negative electrode. The electrode stack has electrode exposure portions exposed from the sealing body at one end and the other end in the stacking direction. Between adjacent energy storage modules, conductive plates are disposed in contact with the electrode exposure portions between opposing electrode exposure portions, and at least a portion between opposing sealing bodies is filled with sealing members.

Description

Technical Field

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

[0002] As existing energy storage devices, energy storage devices comprising multiple stacked energy storage modules are known. Furthermore, as existing energy storage modules, bipolar batteries are known to have bipolar electrodes with a positive electrode formed on one side of the electrode plate and a negative electrode formed on the other side. For example, the bipolar battery disclosed in Japanese Patent Application Laid-Open No. 2005-135764 comprises: an electrode stack consisting of multiple stacked bipolar electrodes; and a battery casing (enclosure) made of polypropylene disposed on the side of the electrode stack. A polypropylene layer is provided at the edge of the bipolar electrodes, and the bipolar electrodes and the battery casing are firmly fixed together by integral molding through the polypropylene layer. This allows for the sealing of the electrolyte. Summary of the Invention

[0003] The problem the invention aims to solve

[0004] In such energy storage modules, when the electrolyte is an alkaline aqueous solution, due to the so-called alkali creep phenomenon, the electrolyte can sometimes propagate across the electrode plates of each electrode, seeping through the gap between the polypropylene layer and the electrode plate to the outer surface of the electrode plate. If alkali creep occurs at the outermost electrode, the electrolyte will leak out of the system. Not limited to alkali creep, if leakage occurs, a short circuit (leakage trace) may occur between the stacked energy storage modules.

[0005] This disclosure provides an energy storage device capable of suppressing short circuits between energy storage modules.

[0006] Solution for solving the problem

[0007] The energy storage device disclosed herein includes: a plurality of stacked energy storage modules; and a conductive plate and a sealing member disposed between adjacent energy storage modules in the stacking direction of the energy storage modules. Each of the plurality of energy storage modules has an electrode stack, an electrolyte, and a sealing body. The electrode stack includes a plurality of electrodes stacked along the stacking direction of the energy storage modules, separated by a separator. The electrolyte is contained in an internal space formed between adjacent electrodes. The sealing body surrounds the side of the electrode stack along the stacking direction and seals the internal space. The plurality of electrodes have a negative terminal electrode, a positive terminal electrode, and a plurality of bipolar electrodes stacked between the negative terminal electrode and the positive terminal electrode. Each of the plurality of bipolar electrodes has an electrode plate, a positive electrode disposed on one side of the electrode plate, and a negative electrode disposed on the other side of the electrode plate. The electrode stack has electrode exposed portions exposed from the sealing body at one end and the other end in the stacking direction. Between adjacent energy storage modules in the stacking direction, a conductive plate is arranged between mutually opposing exposed electrode portions in a manner that contacts the exposed electrode portions, and at least a portion between mutually opposing enclosed bodies is filled with a sealing member.

[0008] In this energy storage device, at least a portion of the space between adjacent energy storage modules in the stacking direction, between opposing enclosures, is filled with a sealing member. Therefore, even if electrolyte leaks from the internal space of the energy storage module and flows out onto the outer peripheral surface of the enclosure, the portion filled with the sealing member can suppress the ingress of electrolyte propagating on the outer peripheral surface of the enclosure. Consequently, short circuits between energy storage modules caused by electrolyte propagating on the outer peripheral surface of the enclosure can be prevented.

[0009] Alternatively, the enclosure may have: an outer peripheral surface along the stacking direction; a pair of end faces facing the stacking direction; and an eaves portion disposed on the outer peripheral surface, extending outward from the electrode stack. Alternatively, the end faces may have: a first portion corresponding to the location of the eaves portion; and a second portion not corresponding to the location of the eaves portion. Alternatively, a sealing member may be provided at least on the second portion. In this case, even if electrolyte flows out to the outer peripheral surface in the first portion of the end face of the enclosure corresponding to the location of the eaves portion, the electrolyte will flow down along the eaves portion, thus suppressing electrolyte ingress. In the second portion not corresponding to the location of the eaves portion, the presence of a sealing member also suppresses electrolyte ingress. Therefore, short circuits between energy storage modules caused by electrolyte propagating on the outer peripheral surface of the enclosure can be reliably suppressed.

[0010] Alternatively, Part 1 and Part 2 can be adjacent to each other in the circumferential direction of the enclosure. Alternatively, a sealing member can also be provided in Part 1. In this case, short circuits between the energy storage modules due to leakage can be further suppressed.

[0011] Alternatively, a cooling flow path for the cooling fluid can be formed in the conductive plate. Alternatively, the conductive plate can be configured such that the inlet and outlet of the cooling flow path correspond to the first part. In this case, the possibility of the inlet and outlet of the cooling flow path being blocked by the sealing member is suppressed.

[0012] Alternatively, the energy storage module may have a pressure regulating valve to adjust the pressure of the internal space. Alternatively, the pressure regulating valve may be mounted on the outer peripheral surface corresponding to the second part. In this case, since no flange is provided on the outer peripheral surface corresponding to the second part, the pressure regulating valve can be easily mounted.

[0013] Alternatively, the sealing member can be bonded to the enclosure. In this case, positional displacement of the sealing member is suppressed. Attached Figure Description

[0014] Figure 1 This is a perspective view of an energy storage device according to one implementation method.

[0015] Figure 2 This is a side view of the energy storage device.

[0016] Figure 3 It is along Figure 1 A cross-sectional view of line III-III.

[0017] Figure 4 It is along Figure 1 A cross-sectional view of line IV-IV.

[0018] Figure 5 It is a 3D view of an energy storage module with sealed components.

[0019] Figure 6 This is a top view of an energy storage module equipped with sealing components.

[0020] Figure 7 This is a cross-sectional view of the energy storage module. Detailed Implementation

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

[0022] Reference Figures 1 to 7 The energy storage device 1 of this embodiment will be explained. Figure 1 This is a three-dimensional view of the energy storage device 1. Figure 2 This is a side view of the energy storage device 1. Figure 3 It is along Figure 1 A cross-sectional view of line III-III. Figure 4 It is along Figure 1 A cross-sectional view of line IV-IV. Figure 5This is a perspective view of the energy storage module 3 equipped with a sealing component S. Figure 6 This is a top view of the energy storage module 3 equipped with a sealing component S. Figure 7 This is a cross-sectional view of the energy storage module 3.

[0023] The energy storage device 1 is used, for example, as a battery for various vehicles such as forklifts, hybrid vehicles, and electric vehicles. The energy storage device 1 includes a modular stack 2 and constraint members 4. The modular stack 2 comprises multiple stacked energy storage modules 3. The constraint members 4 apply constraint loads to the modular stack 2 from both sides of the stacking direction of the energy storage modules 3. The energy storage modules 3 have, for example, a rectangular shape when viewed from the stacking direction. In this specification, for ease of explanation, the stacking direction is defined as the Z-axis direction, the long side direction of the energy storage module 3 when viewed from the stacking direction is defined as the Y-axis direction, and the short side direction of the energy storage module 3 is defined as the X-axis direction.

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

[0025] Multiple energy storage modules 3 are stacked with a conductive plate 5 between them. Energy storage modules 3 adjacent to each other in the stacking direction are electrically connected to each other via the conductive plate 5. In this embodiment, as... Figure 3 As shown, the plurality of (8) conductive plates 5 include a plurality of (6) conductive plates 5A and a plurality of (2) conductive plates 5B (conductive members). The conductive plates 5A are disposed between adjacent energy storage modules 3 in the stacking direction. Between adjacent energy storage modules 3 in the stacking direction, the conductive plates 5A are arranged in contact with the electrode exposure portions 31b of the opposing electrode stacks 31. The electrode exposure portions 31b will be described later. The conductive plates 5B are disposed on the outer side of the energy storage module 3 located at the stacking end in the stacking direction. Figure 1 and Figure 2 As shown, the positive terminal 6 (electrode terminal) is connected to a conductive plate 5B. The negative terminal 7 (electrode terminal) is connected to another conductive plate 5B. The positive terminal 6 and the negative terminal 7 protrude from the edge of the conductive plate 5B in a direction intersecting the stacking direction (Y-axis direction). The charging and discharging of the energy storage device 1 is carried out through the positive terminal 6 and the negative terminal 7.

[0026] like Figure 3 and Figure 4As shown, multiple cooling flow paths 5a are formed on the conductive plate 5A for the flow of cooling fluid. Here, the cooling fluid may be, for example, air or water. The cooling flow paths 5a extend along an intersecting direction (X-axis direction) that intersects the stacking direction (Z-axis direction). The extending direction (X-axis direction) of the cooling flow paths 5a is orthogonal to both the stacking direction (Z-axis direction) and the lead-out direction (Y-axis direction) of the positive terminal 6 and the negative terminal 7. The conductive plate 5A functions as a heat sink to dissipate heat generated in the energy storage module 3 by allowing the cooling fluid to flow through the cooling flow paths 5a.

[0027] The conductive plate 5 has, for example, a rectangular shape when viewed from the stacking direction. A pair of ends 5b and 5c of the cooling flow path 5a are respectively disposed on a pair of sides of the conductive plate 5 facing the X-axis. In this embodiment, the area of ​​the conductive plate 5 when viewed from the stacking direction is smaller than the area of ​​the energy storage module 3. From the viewpoint of improving heat dissipation, the area of ​​the conductive plate 5 may be the same as or larger than the area of ​​the energy storage module 3.

[0028] A sealing member S is disposed between adjacent energy storage modules 3 in the stacking direction. In this embodiment, the sealing member S is disposed together with the conductive plate 5A between adjacent energy storage modules 3 in the stacking direction. The sealing member S is disposed on the outside of the conductive plate 5A. Alternatively, the sealing member S may also be disposed together with the conductive plate 5B on the outside of the energy storage module 3 located at the stacking end in the stacking direction. The specific configuration of the sealing member S will be described later.

[0029] like Figure 1 , Figure 2 as well as Figure 4 As shown, the energy storage device 1 has an inlet pipe 21 and an outlet pipe 22 for the flow of cooling fluid to the energy storage module 3. Here, Figure 4 A cross-section of a plane along the central portion of a conductive plate 5A passing through the stacking direction is shown. Figure 4 For ease of explanation, only one conductive plate 5A, inlet pipe 21, and outlet pipe 22 are shown in the diagram.

[0030] The inlet pipe 21 is configured to be opposite to one end 5b of each cooling flow path 5a of each conductive plate 5A and extend along the Y-axis direction. The inlet pipe 21 is configured to allow cooling fluid to flow and introduce the cooling fluid into the cooling flow path 5a. An inlet port 21a for introducing cooling fluid into the inlet pipe 21 is provided at one end in the Y-axis direction. After being introduced into the end 5b of the cooling flow path 5a from the inlet pipe 21, the cooling fluid flows in the cooling flow path 5a and exits from the other end 5c of the cooling flow path 5a.

[0031] The outlet pipe 22 is configured to face the end 5c of each cooling flow path 5a of each conductive plate 5A and extend along the Y-axis. The outlet pipe 22 is configured to allow cooling fluid to flow after exiting from the end 5c of the cooling flow path 5a. An outlet port 22a for discharging cooling fluid from the outlet pipe 22 to the outside is provided at one end of the outlet pipe 22 in the Y-axis direction. At the outlet port 22a, for example, a blower or the like is connected to draw the cooling fluid in the outlet pipe 22.

[0032] like Figure 1 and Figure 2 As shown, the constraint member 4 includes: a pair of constraint plates 8 (constraint plate 8A on the negative end 7 side and constraint plate 8B on the positive end 6 side) sandwiching the module stack 2 from both sides in the stacking direction; and a plurality of (ten in this embodiment) connecting members 9 that connect the pair of constraint plates 8. The connecting members 9 apply constraint loads to the module stack 2 in the stacking direction via the pair of constraint plates 8. In this embodiment, the connecting members 9 include bolts 9a and nuts 9b for fastening the pair of constraint plates 8.

[0033] The constraint plate 8 is a rectangular metal plate with an area that is larger than that of the energy storage module 3 and the conductive plate 5 when viewed from the stacking direction. An insulating film F, such as a resin film, is disposed between each constraint plate 8 and the conductive plate 5B. The constraint plate 8 and the conductive plate 5B are insulated by the insulating film F. The insulating film F has, for example, a rectangular shape when viewed from the stacking direction. In this embodiment, the area of ​​the insulating film F when viewed from the stacking direction is larger than that of the energy storage module 3 and the conductive plate 5, but smaller than that of the constraint plate 8.

[0034] The constraint plate 8 has: a central portion 11 that overlaps with the module stack 2 when viewed from the stacking direction; and edge portions 10 that extend from the central portion 11 in a direction orthogonal to the stacking direction (the Y-axis direction in this embodiment) and do not overlap with the module stack 2 when viewed from the stacking direction. In this embodiment, a pair of edge portions 10 are provided on both sides of the central portion 11 in the X-axis direction. That is, the central portion 11 is sandwiched by a pair of edge portions 10. The edge portions 10 have: an outer surface 10a facing outward in the stacking direction; and an inner surface 10b facing inward in the stacking direction. The central portion 11 has: an outer surface 11a facing outward in the stacking direction; and an inner surface 11b facing inward in the stacking direction. The outer surface 10a is located inward in the stacking direction than the outer surface 11a. The inner surface 10b is located inward in the stacking direction than the inner surface 11b.

[0035] A pair of edges 10 are outer edge portions extending along the long side direction (Y-axis direction) of the constraint plate 8. The pair of edges 10 are configured not to overlap with the module stack 2 when viewed from the stacking direction. Each edge 10 is provided with a plurality of (five in this embodiment) through holes 10c for inserting bolts 9a. In each edge 10, the plurality of through holes 10c are configured to be separated from each other along the long side direction (Y-axis direction) of the constraint plate 8. In this embodiment, the plurality of through holes 10c are arranged at equal intervals from one end to the other of the edge 10 along the long side direction of the constraint plate 8.

[0036] The head of bolt 9a is positioned on the outer surface 10a of constraint plate 8A. The tip of the shaft portion of bolt 9a (screw head) protrudes from the outer surface 10a of constraint plate 8B. Nut 9b is screwed onto the tip of bolt 9a. Nut 9b is positioned on the outer surface 10a of constraint plate 8B. Thus, multiple energy storage modules 3 and multiple conductive plates 5 are clamped by constraint plates 8A and 8B and unitized into a module stack 2. In addition, the module stack 2 is subjected to constraint loads in the stacking direction.

[0037] The inner surface 10b is located on the outermost side of the stacking direction compared to any of the conductive plates 5A. That is, when viewed from the X-axis direction, the inner surface 10b is located on the outermost side of the stacking direction compared to the outermost conductive plate 5A among the plurality of conductive plates 5A. In other words, the inlet (end 5b) or outlet (end 5c) of the cooling flow path 5a of any conductive plate 5A is not covered by the edge 10. Therefore, cooling fluid can be smoothly introduced from the inlet pipe 21 into the cooling flow path 5a, and cooling fluid can be smoothly discharged from the cooling flow path 5a to the outlet pipe 22. Thus, cooling fluid can reliably flow through the cooling flow path 5a of the conductive plate 5A.

[0038] As described above, the positive terminal 6 and the negative terminal 7 protrude from the side of the conductive plate 5B along the short side direction (X-axis direction) (the side direction intersecting the Y-axis direction). Thus, by leading the electrode terminals (positive terminal 6 and negative terminal 7) from the side of the conductive plate 5B that is not opposite to the edge portion 10, interference between the electrode terminals and the edge portion 10 can be reliably prevented. Furthermore, when the inlet channel 21 and outlet channel 22 are provided at positions opposite to the side of the module stack 2 along the long side direction (Y-axis direction), as in this embodiment, interference between the electrode terminals and the inlet channel 21 or outlet channel 22 can also be prevented.

[0039] like Figure 1As shown, in this embodiment, the inlet pipe 21 is fixed to one edge 10 (edge ​​10 on the side of one end 5b of the cooling flow path 5a) by four fixing screws 18A. The outlet pipe 22 is fixed to another edge 10 (edge ​​10 on the side of the other end 5c of the cooling flow path 5a) by four fixing screws 18B. Each edge 10 is provided with four screw holes (not shown) for engaging the fixing screws 18A and 18B. The four screw holes are located near the four connecting members 9 other than the connecting member 9 located at the center of the long side of the constraint plate 8.

[0040] The inlet pipe 21 and the outlet pipe 22 have extensions 21b and 22b, respectively. The extensions 21b and 22b extend along a plane orthogonal to the lamination direction (XY plane) opposite to the screw holes of each edge 10. Through holes corresponding to the screw holes of each edge 10 are formed in the extensions 21b and 22b. Fixing screws 18A and 18B are inserted into these through holes and screwed into the hole 19. Thus, the inlet pipe 21 and the outlet pipe 22 are fixed to the edge 10.

[0041] like Figures 5-7 As shown, the energy storage module 3 includes an electrode stack 31, a resin enclosure 40, and a pressure regulating valve 52. The electrode stack 31 includes multiple electrodes stacked along the stacking direction (Z-axis direction) of the energy storage module 3, separated by a separator 33. The multiple electrodes include a negative terminal electrode 38, a positive terminal electrode 39, and a stack of multiple bipolar electrodes 34 stacked between the negative terminal electrode 38 and the positive terminal electrode 39. Furthermore, in the example shown, a current-collecting foil 44 is disposed outside the negative terminal electrode 38, and a current-collecting foil 45 is disposed outside the positive terminal electrode 39. In this electrode stack 31, a single cell is formed by a pair of electrodes facing each other separated by a separator 33.

[0042] The bipolar electrode 34 includes: an electrode plate 35 comprising a surface 35a and a surface 35b opposite to the surface 35a; a positive electrode 36 disposed on the surface 35a; and a negative electrode 37 disposed on the surface 35b. The positive electrode 36 is a layer of positive active material formed by coating the electrode plate 35 with a positive active material. The negative electrode 37 is a layer of negative active material formed by coating the electrode plate 35 with a negative active material. In the electrode stack 31, the positive electrode 36 of one bipolar electrode 34 faces the negative electrode 37 of another adjacent bipolar electrode 34 in the stacking direction, separated by a separator 33. In the electrode stack 31, the negative electrode 37 of one bipolar electrode 34 faces the positive electrode 36 of another adjacent bipolar electrode 34 in the stacking direction, separated by a separator 33. Thus, in the electrode stack 31, multiple bipolar electrodes 34 are stacked in series, separated by separators 33.

[0043] Electrode plate 35 comprises a metal such as nickel or nickel-plated steel. As an example, electrode plate 35 is a rectangular metal foil comprising nickel. The edge 35c of electrode plate 35 is rectangular and represents the uncoated area where neither the positive nor negative electrode active material is applied. Examples of positive electrode active materials constituting positive electrode 36 include nickel hydroxide. Examples of negative electrode active materials constituting negative electrode 37 include hydrogen storage alloys. In this embodiment, the area where the negative electrode 37 is formed on the other side 35b of electrode plate 35 is larger than the area where the positive electrode 36 is formed on one side 35a of electrode plate 35.

[0044] The negative terminal electrode 38 includes an electrode plate 35 and a negative electrode 37 disposed on the other side 35b of the electrode plate 35. The negative terminal electrode 38 is positioned at one end in the stacking direction with its other side 35b facing the center of the electrode stack 31. One side 35a of the electrode plate 35 of the negative terminal electrode 38 forms an outer side surface of the electrode stack 31 in the stacking direction. The negative electrode 37 disposed on the other side 35b of the electrode plate 35 of the negative terminal electrode 38 faces the positive electrode 36 of the bipolar electrode 34 at one end in the stacking direction, separated by a separator 33. Furthermore, as described later, the negative terminal electrode 38 can be electrically connected to a conductive plate 5 (see reference 5) disposed adjacent to the energy storage module 3. Figure 3 ).

[0045] The positive terminal electrode 39 includes an electrode plate 35 and a positive electrode 36 disposed on one surface 35a of the electrode plate 35. The positive terminal electrode 39 is positioned at the other end of the stacking direction with one surface 35a facing the center of the electrode stack 31. The other surface 35b of the electrode plate 35 of the positive terminal electrode 39 forms another outer surface of the electrode stack 31 in the stacking direction. The positive electrode 36 disposed on one surface 35a of the electrode plate 35 of the positive terminal electrode 39 faces the negative electrode 37 of the bipolar electrode 34 at the other end of the stacking direction, separated by an separator 33. Furthermore, as described later, the positive terminal electrode 39 can be electrically connected to a conductive plate 5 (see reference 5) disposed adjacent to the energy storage module 3. Figure 3 ).

[0046] As an example, the current collector foil 44 can be an electrode plate 35. In the current collector foil 44, neither the positive electrode active material nor the negative electrode active material is coated on either side 35a or the other side 35b of the electrode plate 35. The current collector foil 44 is in contact with the negative electrode terminal electrode 38. Similarly, as an example, the current collector foil 45 can be an electrode plate 35. In the current collector foil 45, neither the positive electrode active material nor the negative electrode active material is coated on either side 35a or the other side 35b of the electrode plate 35. The current collector foil 45 is in contact with the positive electrode terminal electrode 39. Furthermore, although the current collector foils 44 and 45 are shown bent toward each other in the example figures, they can also be bent toward each other in a direction away from each other. For example, the current collector foils 44 and 45 can be bent to protrude further outward in the stacking direction than the end of the cylindrical portion 32 described later.

[0047] The separator 33 may be formed in the form of a sheet, for example. Examples of separator 33 include porous membranes made of polyolefin resins such as polyethylene (PE) and polypropylene (PP), as well as woven or nonwoven fabrics made of polypropylene, methylcellulose, etc. The separator 33 may also be a separator reinforced with a vinylidene fluoride resin compound.

[0048] The electrode stack 31 has electrode exposure portions 31b at one end and the other end in the stacking direction (Z-axis direction), which protrude from the enclosure 40. In this embodiment, the electrode exposure portion 31b includes the central region of the current collector foils 44 and 45 exposed from the enclosure 40. As an example, the electrode exposure portion 31b at one end in the stacking direction includes the central region of one surface 35a of the current collector foil 44 (electrode plate 35) exposed from the enclosure 40. As an example, the electrode exposure portion 31b at the other end in the stacking direction includes the central region of the other surface 35b of the current collector foil 45 (electrode plate 35) exposed from the enclosure 40.

[0049] The enclosure 40 surrounds the side surface 31a of the electrode stack 31 along the stacking direction (Z-axis direction) and encloses the internal space V formed between adjacent electrodes in the electrode stack 31. The enclosure 40 has a cylindrical portion 32 surrounding the side surface 31a. The cylindrical portion 32 has an outer peripheral surface 32a along the stacking direction and a pair of end faces 32b facing the axial direction (Z-axis direction). The cylindrical portion 32 is generally formed into a rectangular cylindrical shape. The cylindrical portion 32 is disposed on the side surface 31a of the electrode stack 31 in a manner that surrounds the edge 35c of the electrode plate 35. The cylindrical portion 32 holds the edge 35c at the side surface 31a. The cylindrical portion 32 is formed, for example, from an alkali-resistant insulating resin. Examples of materials constituting the cylindrical portion 32 include polypropylene (PP), polyphenylene sulfide (PPS), and modified polyphenylene ether (modified PPE).

[0050] The cylindrical portion 32 has multiple first closing portions 41 and second closing portions 42. The first closing portions 41 are joined to the edge 35c of the electrode plate 35. The first closing portions 41 are continuously provided on the entire circumference of the edge 35c on one surface 35a of the electrode plate 35, and appear as a rectangular frame when viewed from the stacking direction. In this embodiment, the first closing portions 41 are provided not only for the bipolar electrode 34, but also for the electrode plates 35 of the negative terminal electrode 38, the positive terminal electrode 39, and the current collector foils 44 and 45. That is, the bipolar electrode 34, the negative terminal electrode 38, the positive terminal electrode 39, the current collector foil 44, and the current collector foil 45 each form an electrode unit on the electrode plate 35 with the first closing portion 41 provided thereon. Furthermore, in the current collector foil 45, the first closing portions 41 are provided on the edges 35c of both one surface 35a and the other surface 35b of the electrode plate 35.

[0051] The first sealing portion 41 is hermetically bonded to a surface 35a of the electrode plate 35, for example, by ultrasonic waves, heat, or the like. The first sealing portion 41 may be a film of a predetermined thickness in the lamination direction. Alternatively, multiple films of a predetermined thickness may be laminated to form a first sealing portion 41 with localized steps. The inner side of the first sealing portion 41 is located between the edges 35c of adjacent electrode plates 35 in the lamination direction. The outer side of the first sealing portion 41 extends further outward than the edges of the electrode plates 35, and its top portion is bonded to the second sealing portion 42 by a weld layer 46. The weld layer 46 is formed, for example, by melting the top portions of the first sealing portions 41 together using hot plate welding. The first sealing portions 41 adjacent to each other along the lamination direction may be separate or in contact. Furthermore, the outer edges of the first sealing portions 41 may also be bonded together by, for example, hot plate welding.

[0052] The area where the electrode plate 35 overlaps with the first sealing portion 41 is the joint area K of the electrode plate 35 and the first sealing portion 41. In the joint area K, the surface of the electrode plate 35 is roughened. The roughened area may be only the joint area K, but in this embodiment, the entire surface of the electrode plate 35 is roughened. Roughening can be achieved, for example, by forming multiple protrusions using electroplating. By forming multiple protrusions, molten resin enters between the multiple protrusions formed by roughening at the joint interface between the electrode plate 35 and the first sealing portion 41, providing an anchoring effect. This improves the bonding strength between the electrode plate 35 and the first sealing portion 41. The protrusions formed during roughening have, for example, a shape that thickens from the base end to the top end. This results in an undercut shape between adjacent protrusions, enhancing the anchoring effect.

[0053] The second closure 42 surrounds the first closure 41 from the outside along the side 31a and is joined to each of the first closures 41. The second closure 42 is disposed on the outside of the unit stack 43 including the electrode stack 31 and the first closure 41, forming the outer wall of the energy storage module 3. The second closure 42 is formed, for example, by resin injection molding, and extends along the entire length of the electrode stack 31 in the stacking direction. The second closure 42 has a rectangular cylindrical shape extending axially in the stacking direction. The second closure 42 is fused to the outer surface of the first closure 41, for example, by the heat during injection molding.

[0054] The first sealing portion 41 and the second sealing portion 42 form an internal space V between adjacent electrodes and seal the internal space V. More specifically, the second sealing portion 42, together with the first sealing portion 41, seals the spaces between adjacent bipolar electrodes 34 along the stacking direction, between adjacent negative terminal electrodes 38 and bipolar electrodes 34 along the stacking direction, and between adjacent positive terminal electrodes 39 and bipolar electrodes 34 along the stacking direction. Thus, airtightly separated internal spaces V are formed between adjacent bipolar electrodes 34, between negative terminal electrodes 38 and bipolar electrodes 34, and between positive terminal electrodes 39 and bipolar electrodes 34.

[0055] As an example, in this embodiment, 24 internal spaces V are formed by stacked electrodes. An electrolyte (not shown) containing, for example, an alkaline solution such as an aqueous solution of potassium hydroxide is contained within each internal space V. The electrolyte is impregnated into the separator 33, the positive electrode 36, and the negative electrode 37. An injection port (not shown) for injecting electrolyte into the internal spaces V is provided on the outer peripheral surface 32a of the cylindrical portion 32. The outer peripheral surface 32a is formed by the outer peripheral surface of the second sealing portion 42.

[0056] In this embodiment, the cylindrical portion 32 includes: a pair of long side portions extending along the Y-axis direction; and a pair of short side portions extending along the X-axis direction. The circumferential direction of the cylindrical portion 32 is the Y-axis direction in the long side portions and the X-axis direction in the short side portions. The outer peripheral surface 32a faces the X-axis direction in the long side portions and faces the Y-axis direction in the short side portions. An injection port (not shown) for injecting electrolyte into the internal space V is provided on the outer peripheral surface 32a of one of the short side portions.

[0057] The enclosure 40 has an eave 51, which is disposed on the outer peripheral surface 32a of the cylindrical portion 32 and extends outward from the outer peripheral surface 32a toward the outside of the electrode stack 31. The eave 51 protrudes from the outer peripheral surface 32a and extends along the circumferential direction of the cylindrical portion 32. In this embodiment, one eave 51 is provided on the outer peripheral surface 32a of each long side portion of the cylindrical portion 32 and extends along the circumferential direction (Y-axis direction) of the cylindrical portion 32.

[0058] The eaves 51 is reinforced by a plurality of ribs 53 provided on the outer peripheral surface 32a. The plurality of ribs 53 are provided at predetermined intervals in the extending direction (Y-axis direction) of the eaves 51. The eaves 51 and ribs 53 are formed, for example, of an alkali-resistant insulating resin. The eaves 51 and ribs 53 are formed, for example, of the same material as the cylindrical portion 32. The eaves 51 and ribs 53 are integrally formed with the second closure portion 42, for example, by resin injection molding.

[0059] The end face 32b of the cylindrical portion 32 includes: a first portion 32A, which corresponds to the location of the eaves 51; and a second portion 32B, which does not correspond to the location of the eaves 51. The first portion 32A and the eaves 51 are aligned in the circumferential direction of the cylindrical portion 32. The second portion 32B and the eaves 51 are not aligned in the circumferential direction of the cylindrical portion 32. In this embodiment, the end face 32b includes a pair of first portions 32A and a pair of second portions 32B. The first portion 32A is the end face of the portion of the cylindrical portion 32 excluding the two ends of the long side portion. The first portion 32A has a pair of ends 32Aa in the circumferential direction (Y-axis direction) of the cylindrical portion 32. The ends 32Aa are the boundary portions of the first portion 32A with the second portions 32B. A second portion 32B is the end face of a U-shaped portion formed by a short side portion of the cylindrical portion 32 and the end portion on the short side side of one of the pair of long side portions. The other second part 32B is the end face of a U-shaped portion formed by the other short side portion of the cylindrical portion 32 and the end of the other short side portion of a pair of long side portions. The first part 32A and the second part 32B are adjacent to each other in the circumferential direction of the cylindrical portion 32 (closed body 40).

[0060] The outer peripheral surface 32a corresponding to part 32A is adjacent in the stacking direction to the side surface of the conductive plate 5A, which has the inlet (end 5b) and outlet (end 5c) of the cooling flow path 5a. That is, the conductive plate 5 is configured such that the inlet and outlet of the cooling flow path 5a correspond to part 32A. The outer peripheral surface 32a corresponding to part 32A and the side surface of the conductive plate 5A, which has the inlet and outlet of the cooling flow path 5a, face the same direction (X-axis direction).

[0061] The eaves 51 are mounted above the center of the outer peripheral surface 32a in the stacking direction and slope downwards. The length of the eaves 51 in the stacking direction is shorter than the length of the outer peripheral surface 32a in the stacking direction. The eaves 51 is disposed inside the outer peripheral surface 32a in the stacking direction. Therefore, the inlet (end 5b) and outlet (end 5c) of the cooling flow path 5a of the conductive plate 5A are not covered by the eaves 51. As a result, the cooling fluid can flow smoothly in the cooling flow path 5a.

[0062] A pressure regulating valve 52 is mounted on the outer peripheral surface 32a corresponding to one of the second portions 32B. The pressure regulating valve 52 is connected to a liquid inlet (not shown) provided on the outer peripheral surface 32a to adjust the pressure of the internal space V. In this embodiment, two pressure regulating valves 52 are mounted on the outer peripheral surface 32a of one short side portion of the cylinder 32.

[0063] The sealing member S fills at least a portion of the space between opposing enclosures 40 between adjacent energy storage modules 3 in the stacking direction. Two sealing members S are disposed between each adjacent energy storage module 3 in the stacking direction. The sealing member S seals the space between the cylindrical portions 32 of adjacent energy storage modules 3 in the stacking direction. The sealing member S is provided at least throughout the entire second portion 32B. In this embodiment, the sealing member S is provided not only in the second portion 32B but also at the end 32Aa of the first portion 32A. The sealing member S contacts the second portion 32B and also contacts the end 32Aa of the first portion 32A.

[0064] The sealing member S extends along the circumference of the cylindrical portion 32 (X-axis direction in the short side portion and Y-axis direction in the long side portion). The sealing member S has a pair of ends Sa in the circumferential direction of the cylindrical portion 32. The ends Sa are configured to contact the ends 32Aa. That is, the sealing member S is provided at the ends 32Aa, and an eave 51 is provided on the outer circumferential surface 32a corresponding to the ends 32Aa.

[0065] In adjacent energy storage modules 3 along the stacking direction, the end faces 32b of the cylindrical portions 32 face each other. The sealing member S is clamped and compressed by the opposing end faces 32b in the stacking direction. Thus, the sealing member S liquid-tightly seals the space between the cylindrical portions 32. The sealing member S is configured to contact the end faces 32b. The sealing member S is, for example, a sponge sealing member (foam sealing member) that is softer than the cylindrical portions 32 and has liquid-tight properties. Therefore, the sealing member S is easily compressed by the cylindrical portions 32 and adheres tightly to the end faces 32b, thus providing a seal. Examples of materials used to construct the sealing member S include EPDM (ethylene propylene diene rubber). The sealing member S is, for example, formed from an insulating resin with alkali resistance.

[0066] exist Figure 5 and Figure 6 The image shows the state of the energy storage module 3 before it is stacked. When stacking the energy storage module 3, for example, as shown... Figure 5 and Figure 6 As shown, the sealing member S is pre-positioned on the end face 32b of the cylindrical portion 32. With the sealing member S in place, the energy storage modules 3 are sequentially stacked, thereby clamping the sealing member S between adjacent energy storage modules 3 in the stacking direction. The sealing member S is, for example, bonded to the end face 32b. Thus, positional displacement of the sealing member S during and after the stacking of the energy storage modules 3 is suppressed.

[0067] As explained above, in the energy storage device 1, at least a portion of the space between adjacent energy storage modules 3 in the stacking direction, between the opposing enclosures 40, is filled with a sealing member S. Therefore, even if electrolyte leaks from the internal space V of the energy storage module 3 and flows out to the outer peripheral surface 32a, the portion filled with the sealing member S can suppress the entry of electrolyte propagating on the outer peripheral surface 32a. Thus, short circuits between the energy storage modules 3 caused by electrolyte propagating on the outer peripheral surface 32a can be suppressed. Furthermore, the leakage of electrolyte to the outer peripheral surface 32a in the portion filled with the sealing member S is suppressed. Therefore, short circuits between the energy storage modules 3 caused by electrolyte propagating on the outer peripheral surface 32a can also be suppressed. In addition, causes of leakage from the energy storage module 3 include, for example, alkaline creep or damage to the electrode plates 35, including the current collector foils 45 and 44.

[0068] The end face 32b of the enclosure 40 has a first portion 32A corresponding to the location of the eaves 51 on the outer peripheral surface 32a, and a second portion 32B not corresponding to the location of the eaves 51 on the outer peripheral surface 32a. A sealing member S is provided at least on the second portion 32B. In the first portion 32A, even if electrolyte flows out onto the outer peripheral surface 32a, the electrolyte will fall down along the eaves 51, thus suppressing electrolyte ingress. In the second portion 32B, due to the presence of the sealing member S, electrolyte ingress is suppressed. Therefore, short circuits between the energy storage modules 3 caused by electrolyte propagating on the outer peripheral surface 32a can be reliably suppressed. Furthermore, in the second portion 32B, electrolyte outflow onto the outer peripheral surface 32a is suppressed. The electrolyte is guided to the first portion 32A side by the sealing member S. As described above, the electrolyte flowing from the first part 32A side to the outer peripheral surface 32a falls down along the eaves 51.

[0069] Part 1 32A and Part 2 32B are adjacent to each other in the circumferential direction of the enclosure 40, and a sealing member S is also provided in Part 1 32A. Specifically, the sealing member S is also provided at the end 32Aa of Part 1 32A. End 32Aa is the boundary between Part 1 32A and Part 2 32B, so electrolyte can easily reach End 32Aa from the portion of the outer peripheral surface 32a where the eaves 51 is not provided. However, since the sealing member S is provided at End 32Aa, the ingress of electrolyte can be suppressed. As a result, short circuits between the energy storage modules 3 due to leakage can be further suppressed. In addition, electrolyte flowing out from End 32Aa can easily reach the portion of the outer peripheral surface 32a where the eaves 51 is not provided. However, since the sealing member S is provided at End 32Aa, the outflow of electrolyte from End 32Aa to the outer peripheral surface 32a and to the outer peripheral surface 32a of Part 2 32B can be suppressed.

[0070] Multiple cooling flow paths 5a are formed in the conductive plate 5A to allow cooling fluid to flow through. The conductive plate 5A is configured such that the inlet (end 5b) and outlet (end 5c) of the cooling flow paths 5a correspond to the first part 32A. An eave 51 is provided on the outer peripheral surface 32a corresponding to the first part 32A, and the eave 51 can suppress short circuits between the energy storage modules 3. Therefore, there is no need to provide a sealing member S in the first part 32A, and thus it is possible to prevent the ends 5b and 5c of the cooling flow paths 5a from being blocked by the sealing member S.

[0071] The pressure regulating valve 52 is mounted on the outer peripheral surface 32a corresponding to one of the second portions 32B. Since no eaves 51 are provided on the outer peripheral surface 32a corresponding to the second portion 32B, the pressure regulating valve 52 can be easily mounted. Because the pressure regulating valve 52 is mounted on the outer peripheral surface 32a corresponding to one of the second portions 32B, there is no space for the eaves 51. According to the sealing member S, even in a second portion 32B where there is no space for the eaves 51 on the corresponding outer peripheral surface 32a, the ingress of electrolyte can be suppressed, thus preventing short circuits between the energy storage modules 3. In this embodiment, the pressure regulating valve 52 is not provided on the other second portion 32B. Therefore, for example, other components (not shown) can be arranged in contact with the outer peripheral surface 32a of the other second portion 32B.

[0072] The sealing member S is bonded to the end face 32b of the cylindrical portion 32. Therefore, the positional displacement of the sealing member S is suppressed.

[0073] The above describes the energy storage device 1 according to the embodiment, but the present invention is not limited to the above embodiment. For example, an eave 51 may be provided on the outer peripheral surface 32a corresponding to the other second part 32B. Although the sealing member S is configured to contact the second closing part 42 in the end face 32b, it may also be configured to contact the first closing part 41, or it may be configured to contact both the first closing part 41 and the second closing part 42. The eaves 51 may also be arranged in two or more rows in the stacking direction, each protruding from the outer peripheral surface 32a and extending circumferentially along the cylindrical part 32.

Claims

1. An energy storage device, comprising: Multiple stacked energy storage modules; and A conductive plate and a sealing member are disposed between adjacent energy storage modules in the stacking direction of the aforementioned energy storage modules. The aforementioned energy storage device is characterized in that, Each of the aforementioned energy storage modules comprises: an electrode stack comprising a plurality of electrodes stacked along the stacking direction of the energy storage module, separated by a separator; an electrolyte contained in an internal space formed between adjacent electrodes; and a sealing body surrounding the sides of the electrode stack along the stacking direction and sealing the internal space. The aforementioned plurality of electrodes have a negative terminal electrode, a positive terminal electrode, and a plurality of bipolar electrodes stacked between the negative terminal electrode and the positive terminal electrode. Each of the aforementioned bipolar electrodes has an electrode plate, a positive electrode disposed on one side of the electrode plate, and a negative electrode disposed on the other side of the electrode plate. The aforementioned electrode stack has exposed electrode portions at one end and the other end in the aforementioned stacking direction, which protrude from the aforementioned enclosed body. Between adjacent energy storage modules in the aforementioned stacking direction, a conductive plate is disposed in contact with the exposed electrode portions facing each other, and at least a portion between the opposing enclosures is filled with the aforementioned sealing member. The aforementioned enclosure has: a plurality of first sealing portions that engage with the edge of the aforementioned electrode; and a second sealing portion that surrounds the plurality of first sealing portions along the aforementioned side surface. The sealing component described above is more flexible than the closure body described above.

2. The energy storage device according to claim 1, wherein, The aforementioned enclosure has: an outer peripheral surface along the aforementioned stacking direction; a pair of end faces facing the aforementioned stacking direction; and an eaves disposed on the aforementioned outer peripheral surface, extending outward from the outer side of the aforementioned electrode stack. The aforementioned end face has: a first portion, which corresponds to the location of the aforementioned eaves; and a second portion, which does not correspond to the aforementioned location. The aforementioned sealing member is provided at least on the second part.

3. The energy storage device according to claim 2, wherein, The first part and the second part mentioned above are adjacent to each other in the circumferential direction of the closed body. The aforementioned sealing component is also provided in the aforementioned Part 1.

4. The energy storage device according to claim 2 or 3, wherein, The aforementioned conductive plate has a cooling flow path for allowing cooling fluid to circulate. The conductive plate is configured such that the inlet and outlet of the cooling flow path correspond to the first part mentioned above.

5. The energy storage device according to claim 2 or 3, wherein, The aforementioned energy storage module has a pressure regulating valve for adjusting the pressure in the aforementioned internal space. The pressure regulating valve described above is mounted on the outer peripheral surface corresponding to the second part described above.

6. The energy storage device according to any one of claims 1 to 3, wherein, The aforementioned sealing component is bonded to the aforementioned enclosure.

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