Power storage module

Abstract

A storage battery module comprises: a stack including a plurality of electrodes stacked along a first direction; a sealing body arranged on the stack in a manner surrounding the peripheral portion of the electrode, forming an internal space for storing an electrolyte between the electrodes adjacent to each other along the first direction, and sealing the internal space; and a reinforcing body arranged on the electrode for suppressing deformation of the electrode, the electrode including a plurality of bipolar electrodes and a negative terminal electrode, the bipolar electrode including an electrode plate, a positive electrode arranged on a first surface of the electrode plate, and a negative electrode arranged on a second surface of the electrode plate opposite to the first surface, the negative terminal electrode including the electrode plate and the negative electrode arranged on the second surface, and arranged at one end of the stack in the first direction in a manner such that the second surface faces the inner side of the stack in the first direction.

Description

Technical Field

[0001] One aspect of the present invention relates to a power storage module. Background Art

[0002] Patent document 1 describes a bipolar battery. The bipolar battery includes a battery element including a plurality of stacked bipolar electrodes. The bipolar electrode includes: a current collector; a positive electrode layer provided on one surface of the current collector; and a negative electrode layer provided on the other surface of the current collector. In addition, the bipolar battery includes a resin group covering the outside of the battery element. The resin group is provided to keep the battery element airtight (liquid-tight) so that the electrolyte inside the battery does not leak to the outside.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Publication No. 2005-005163 Summary of the invention

[0006] Problem that the invention aims to solve

[0007] In the above-mentioned bipolar battery, for example, when the internal pressure rises, although the load is eliminated in the bipolar electrode located in the middle part of the stacking direction of the bipolar electrodes, the load is not eliminated in the outermost bipolar electrode, which may cause the collector and the resin group to deform. In this case, a gap sometimes occurs between the resin group and the collector, causing leakage of the electrolyte or damage to the resin group. In particular, in the case where the negative electrode layer is located at the outermost part and the electrolyte includes an alkaline aqueous solution, leakage of the electrolyte from the gap is likely to occur due to the so-called alkali creep phenomenon. In this case, in a storage module such as the above-mentioned bipolar battery, it is expected to suppress leakage and damage and improve reliability.

[0008] Therefore, an object of one aspect of the present invention is to provide a power storage module capable of improving reliability.

[0009] Solutions for solving problems

[0010] The storage module of one aspect of the present invention comprises: a stacked body including a plurality of electrodes stacked along a first direction; a sealing body provided on the stacked body in a manner surrounding the peripheral edge of the electrode, forming an internal space for storing an electrolyte between the electrodes adjacent to each other along the first direction and sealing the internal space; and a reinforcing body provided on the electrode for suppressing deformation of the electrode, the electrode including a plurality of bipolar electrodes and a negative terminal electrode, the bipolar electrode including an electrode plate, a positive electrode provided on a first surface of the electrode plate, and a positive electrode provided on a surface opposite to the first surface of the electrode plate. A negative electrode on the second surface of one side, the negative terminal electrode includes an electrode plate and a negative electrode arranged on the second surface, and is arranged at one end of the stack in the first direction in a manner that the second surface faces the inner side of the stack in the first direction, the sealing body includes: a plurality of first sealing parts, which are fused to the first surface at the peripheral portion of the electrode; and a second sealing part, which is joined to the first sealing part in a manner of surrounding the plurality of first sealing parts from the outer side in the first direction, and the reinforcing body includes a first reinforcing part, and the first reinforcing part is joined to the second surface of the negative terminal electrode at the peripheral portion of the negative terminal electrode.

[0011] In the power storage module, the electrode includes a plurality of bipolar electrodes and a negative terminal electrode arranged at one end of the stack in the first direction. The sealing body includes: a plurality of first sealing portions which are fused to the first surface of the electrode at the peripheral portion of the electrode; and a second sealing portion which is joined to the first sealing portion in a manner of surrounding the plurality of first sealing portions from the outside in the first direction. The reinforcing body includes a first reinforcing portion joined to the second surface of the negative terminal electrode. Thus, in the bipolar electrode, the first sealing portion is fused to the first surface, and in the negative terminal electrode, the first sealing portion is fused to the first surface and the first reinforcing portion is joined to the second surface. Therefore, deformation of the negative terminal electrode is suppressed, and leakage or damage of the electrolyte on the negative terminal electrode side is suppressed. Therefore, according to the power storage module, reliability can be improved.

[0012] Alternatively, in an electricity storage module according to one aspect of the present invention, the electrode further includes a positive terminal electrode, the positive terminal electrode includes an electrode plate and a positive electrode provided on the first surface, and is arranged at the other end of the stack in the first direction in such a manner that the first surface faces the inner side of the stack in the first direction, and the reinforcing body further includes a second reinforcing portion, and the second reinforcing portion is joined to the second surface of the positive terminal electrode at the peripheral portion of the positive terminal electrode. In this case, in the bipolar electrode, the first sealing portion is fused to the first surface, and in the positive terminal electrode, the first sealing portion is fused to the first surface and the second reinforcing portion is joined to the second surface, similarly to the negative terminal electrode side. Therefore, deformation of the positive terminal electrode is suppressed, and leakage or damage of the electrolyte on the positive terminal electrode side is suppressed. As a result, the reliability of the electricity storage module is further improved.

[0013] In the power storage module according to one aspect of the present invention, the reinforcing body may be joined to the second sealing portion together with the first sealing portion. In this case, the reinforcing body may be used for sealing the internal space in addition to the first sealing portion.

[0014] Alternatively, in the storage battery module according to one aspect of the present invention, the second sealing portion includes an overlapping portion, and the overlapping portion is provided at one end and the other end of the stack so as to overlap with the electrode when viewed from the first direction. In this case, the negative terminal electrode (and the positive terminal electrode) is reinforced by the overlapping portion, so that deformation of the negative terminal electrode (and the positive terminal electrode) can be further reliably suppressed.

[0015] Alternatively, in the storage battery module according to one aspect of the present invention, the tensile strength of the material of the reinforcing body is greater than the tensile strength of the material of the first sealing portion. In this case, the negative terminal electrode (and the positive terminal electrode (hereinafter the same)) is further reliably reinforced by the reinforcing body, and thus deformation of the negative terminal electrode can be further reliably suppressed.

[0016] In the power storage module according to one aspect of the present invention, the Young's modulus of the material of the reinforcing body may be larger than that of the material of the first sealing portion. In this case, the negative terminal electrode is more reliably reinforced by the reinforcing body, and deformation of the negative terminal electrode can be more reliably suppressed.

[0017] In the power storage module according to one aspect of the present invention, the reinforcing body may be made of polypropylene. In this case, the negative terminal electrode is further reliably reinforced by the reinforcing body, and thus deformation of the negative terminal electrode can be further reliably suppressed.

[0018] In the power storage module according to one aspect of the present invention, the reinforcing body may be made of stretched polypropylene. In this case, the negative terminal electrode is further reliably reinforced by the reinforcing body, and thus deformation of the negative terminal electrode can be further reliably suppressed.

[0019] In the power storage module according to one aspect of the present invention, the reinforcing body may be made of biaxially stretched polypropylene. In this case, the negative terminal electrode is further reliably reinforced by the reinforcing body, and thus deformation of the negative terminal electrode can be further reliably suppressed.

[0020] In the power storage module according to one aspect of the present invention, the reinforcing body may be made of the same material as the first sealing portion. In this case, the materials can be made common.

[0021] Effects of the Invention

[0022] According to one aspect of the present invention, it is possible to provide a power storage module capable of improving reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a schematic cross-sectional view showing one embodiment of a power storage device.

[0024] Figure 2 It is shown Figure 1 A schematic cross-sectional view of the internal structure of the power storage module shown.

[0025] Figure 3 yes Figure 2 A top view of a bipolar electrode is shown.

[0026] Figure 4 yes Figure 2 A top view of the negative terminal electrode is shown.

[0027] Figure 5 yes Figure 2 A top view of the positive terminal electrode is shown.

[0028] Figure 6 It is a partially enlarged cross-sectional view of a power storage module of a comparative example.

[0029] Figure 7 It is a partially enlarged cross-sectional view of a power storage module of a comparative example.

[0030] Figure 8 It is a schematic cross-sectional view showing the internal structure of a power storage module according to a modified example. DETAILED DESCRIPTION

[0031] Hereinafter, one embodiment will be described in detail with reference to the accompanying drawings. In addition, in each figure, the same reference numerals are attached to the same or corresponding parts, and repeated descriptions are omitted.

[0032] Figure 1 This is a schematic cross-sectional view showing one embodiment of a power storage device. Figure 1 The power storage device 1 shown is used as a battery for various vehicles such as forklifts, hybrid vehicles, and electric vehicles. The power storage device 1 includes: a module stack 2 including a plurality of stacked power storage modules 4; and a restraining member 3 for applying a restraining load to the module stack 2 in its stacking direction (here, the stacking direction D of the electrodes in the electrode stack 11 described later).

[0033] The module stack 2 includes: a plurality of (here, 3) power storage modules 4, and a plurality of (here, 4) conductive plates 5. The power storage module 4 is a bipolar battery, and is rectangular when viewed from the stacking direction D. The power storage module 4 is, for example, a secondary battery such as a nickel-hydrogen secondary battery, a lithium-ion secondary battery, or an electric double layer capacitor. In the following description, a nickel-hydrogen secondary battery is exemplified.

[0034] The storage modules 4 adjacent to each other in the stacking direction D are electrically connected to each other via the conductive plates 5. The conductive plates 5 are respectively arranged between the storage modules 4 adjacent to each other in the stacking direction D and outside the storage modules 4 located at the stacking end in the stacking direction D. A positive terminal 6 is connected to one conductive plate 5 arranged outside the storage module 4 located at the stacking end in the stacking direction D. A negative terminal 7 is connected to the other conductive plate 5 arranged outside the storage module 4 located at the stacking end in the stacking direction D. The positive terminal 6 and the negative terminal 7 are drawn out from the edge of the conductive plate 5 in a direction intersecting the stacking direction D, for example. The storage device 1 is charged and discharged through the positive terminal 6 and the negative terminal 7.

[0035] A plurality of flow paths 5a for circulating a refrigerant such as air are provided inside the conductive plate 5. The flow paths 5a extend, for example, in directions intersecting (orthogonal to) the stacking direction D and the lead-out directions of the positive terminal 6 and the negative terminal 7. In addition to functioning as a connecting member for electrically connecting the power storage modules 4 to each other, the conductive plate 5 also functions as a heat sink for dissipating heat generated in the power storage modules 4 by circulating a refrigerant in these flow paths 5a. Figure 1 In the example, when viewed from the stacking direction D, the area of ​​the conductive plate 5 is smaller than the area of ​​the power storage module 4, but from the perspective of improving heat dissipation, the area of ​​the conductive plate 5 can be the same as or larger than the area of ​​the power storage module 4.

[0036] The restraining member 3 includes: a pair of end plates 8 sandwiching the module stack 2 in the stacking direction D; and fastening bolts 9 and nuts 10 fastening the end plates 8 to each other. The end plate 8 is a rectangular metal plate having an area slightly larger than that of the storage module 4 and the conductive plate 5 when viewed from the stacking direction D. An electrically insulating film F is provided on the inner side surface (the surface facing the module stack 2 side) of the end plate 8 in the stacking direction D. The end plate 8 and the conductive plate 5 are insulated by the film F.

[0037] The end plate 8 is provided with an insertion hole 8a at an edge portion on the outer peripheral side of a portion overlapping with the module stack 2 in the stacking direction D. The fastening bolt 9 is passed from the insertion hole 8a of one end plate 8 toward the insertion hole 8a of the other end plate 8, and the nut 10 is screwed to the tip portion of the fastening bolt 9 protruding from the insertion hole 8a of the other end plate 8. Thus, the power storage module 4 and the conductive plate 5 are clamped by the end plate 8 and unitized into the module stack 2, and a restraining load is applied to the module stack 2 in the stacking direction D.

[0038] Next, the configuration of the power storage module 4 will be described in detail. Figure 2 It is shown Figure 1 The schematic cross-sectional view of the internal structure of the power storage module 4 is shown. Figure 2As shown, the storage module 4 includes: an electrode stack (stack) 11; a resin seal 12 that seals the electrode stack 11; and a reinforcing body 23. The electrode stack 11 includes a separator 13, and a plurality of electrodes (a plurality of bipolar electrodes 14, a single negative terminal electrode 18, and a single positive terminal electrode 19) stacked along a stacking direction D (a first direction) with the separator 13 interposed therebetween. Here, the stacking direction D of the electrode stack 11 coincides with the stacking direction of the module stack 2. The electrode stack 11 has a side surface 11a extending in the stacking direction D. As an example, the side surface 11a is formed as a collection of end surfaces (surfaces connecting the first surface 15a and the second surface 15b) of the electrode plate 15 described later.

[0039] The bipolar electrode 14 includes an electrode plate 15, a positive electrode 16 disposed on a first surface 15a of the electrode plate 15, and a negative electrode 17 disposed on a second surface 15b of the electrode plate 15 opposite to the first surface 15a. The electrode plate 15 includes a metal such as nickel or a nickel-plated steel plate. As an example, the electrode plate 15 is a rectangular metal foil including nickel. The electrode plate 15 includes an outer edge 15d that is rectangular when viewed from the stacking direction D.

[0040] The surface of the electrode plate 15 is roughened. Here, the entire surface of the electrode plate 15 including the first surface 15a, the second surface 15b and the end surface connecting the first surface 15a and the second surface 15b is roughened. The surface of the electrode plate 15 is roughened, for example, by forming a plurality of protrusions by electrolytic plating. When the electrode plate 15 is roughened in this way, at the bonding interface between the electrode plate 15 and the first resin part 21, the first reinforcement part 24 and the second reinforcement part 25 described later, the molten first resin part 21, the first reinforcement part 24 and the second reinforcement part 25 enter into the recess formed by the roughening, and exert an anchor effect. As a result, the bonding force between the electrode plate 15 and the first resin part 21, the first reinforcement part 24 and the second reinforcement part 25 can be improved. As long as at least the peripheral edge part 15c in the first surface 15a is roughened, the effect of improving the bonding force can be obtained. The protrusion has a shape that becomes thicker from the base end side toward the tip end side, for example. In this case, the cross-sectional shape between mutually adjacent protrusions becomes an undercut shape, which makes it easy to produce an anchoring effect.

[0041] The positive electrode 16 is a positive electrode active material layer formed by coating a positive electrode active material on the electrode plate 15. As the positive electrode active material constituting the positive electrode 16, nickel hydroxide can be cited, for example. The positive electrode 16 includes an outer edge 16d that is rectangular when viewed from the stacking direction D. The negative electrode 17 is a negative electrode active material layer formed by coating a negative electrode active material on the electrode plate 15. As the negative electrode active material constituting the negative electrode 17, a hydrogen storage alloy can be cited, for example. The negative electrode 17 includes an outer edge 17d that is rectangular when viewed from the stacking direction D.

[0042] In the present embodiment, the formation area of ​​the negative electrode 17 in the second surface 15b of the electrode plate 15 is one circle larger than the formation area of ​​the positive electrode 16 in the first surface 15a of the electrode plate 15. That is, the outer edge 17d of the negative electrode 17 is one circle larger than the outer edge 16d of the positive electrode 16. The peripheral portion 15c of the electrode plate 15 is in the shape of a rectangular frame, and is an uncoated area where the positive electrode active material and the negative electrode active material are not coated. That is, the peripheral portion 15c of the electrode plate 15 is a portion other than the area where the positive electrode 16 and the negative electrode 17 are formed in the electrode plate 15 when viewed from the stacking direction D, and is a portion surrounding the positive electrode 16 and the negative electrode 17. In addition, the surfaces of the bipolar electrode 14, the negative terminal electrode 18, and the positive terminal electrode 19 respectively include the first surface 15a and the second surface 15b in the peripheral portion 15c of the electrode plate 15.

[0043] In the electrode stack 11, the positive electrode 16 of one bipolar electrode 14 faces the negative electrode 17 of another bipolar electrode 14 adjacent in the stacking direction D via the separator 13. In the electrode stack 11, the negative electrode 17 of one bipolar electrode 14 faces the positive electrode 16 of yet another bipolar electrode 14 adjacent in the stacking direction D via the separator 13.

[0044] The negative terminal electrode 18 includes: an electrode plate 15; and a negative electrode 17 provided on the second surface 15b of the electrode plate 15. The negative terminal electrode 18 does not include a positive electrode 16. That is, no active material layer is provided on the first surface 15a of the electrode plate 15 of the negative terminal electrode 18 (that is, the entire first surface 15a of the negative terminal electrode 18 is exposed). The negative terminal electrode 18 is arranged at one end in the stacking direction D in such a manner that the second surface 15b faces the inner side in the stacking direction D of the electrode stack 11 (the center side in the stacking direction D). The negative electrode 17 of the negative terminal electrode 18 faces the positive electrode 16 of the bipolar electrode 14 at one end in the stacking direction D via the separator 13.

[0045] The positive terminal electrode 19 includes: an electrode plate 15; and a positive electrode 16 provided on the first surface 15a of the electrode plate 15. The positive terminal electrode 19 does not include a negative electrode 17. That is, no active material layer is provided on the second surface 15b of the electrode plate 15 of the positive terminal electrode 19 (that is, the entire second surface 15b of the positive terminal electrode 19 is exposed). The positive terminal electrode 19 is arranged at the other end in the stacking direction D in such a way that the first surface 15a faces the inner side in the stacking direction D of the electrode stack 11. The positive electrode 16 of the positive terminal electrode 19 faces the negative electrode 17 of the bipolar electrode 14 at the other end in the stacking direction D through the separator 13.

[0046] The first surface 15a of the electrode plate 15 of the negative terminal electrode 18 is in contact with the conductive plate 5. In addition, the second surface 15b of the electrode plate 15 of the positive terminal electrode 19 is in contact with the conductive plate 5 of the adjacent power storage module 4. The restraint load from the restraint member 3 is applied to the electrode stack 11 from the negative terminal electrode 18 and the positive terminal electrode 19 via the conductive plate 5. That is, the conductive plate 5 is also a restraint member that applies the restraint load to the electrode stack 11 along the stacking direction D.

[0047] The separator 13 is formed into a sheet, for example. Examples of the separator 13 include porous films made of polyolefin resins such as polyethylene (PE) and polypropylene (PP), woven fabrics or nonwoven fabrics made of polypropylene, polyethylene terephthalate (PET), methylcellulose, and the like. The separator 13 may also be a separator reinforced with a vinylidene fluoride resin compound. In addition, the separator 13 is not limited to a sheet, and a bag-shaped separator may also be used.

[0048] The sealing body 12 is formed of, for example, an insulating resin into a cylindrical shape having a generally rectangular cross section. The sealing body 12 is disposed along the side 11a of the electrode stack 11 in a manner that surrounds the peripheral portion 15c. The sealing body 12 holds the peripheral portion 15c. The sealing body 12 comprises: a plurality of first resin portions (a plurality of first sealing portions) 21, which are fused to the first surface 15a and the end surface at the peripheral portion 15c of each electrode; and a single second resin portion (a second sealing portion) 22, which is joined to the first resin portion 21 in a manner that surrounds the first resin portion 21 from the outside in the stacking direction D along the side 11a of the electrode stack 11.

[0049] Figure 3 This is a diagram showing the bipolar electrode 14 to which the first resin portion 21 is welded when viewed from the stacking direction D. Figure 4 The figure shows the negative terminal electrode 18 to which the first resin portion 21 and the first reinforcing portion 24 described later are welded when viewed from the stacking direction D. Figure 5 The diagram shows the positive terminal electrode 19 to which the first resin portion 21 and the second reinforcing portion 25 described later are welded when viewed from the stacking direction D.

[0050] like Figure 2 to Figure 5 As shown, among the bipolar electrode 14, the negative terminal electrode 18, and the positive terminal electrode 19, the negative electrode 17 is one size smaller than the electrode plate 15. That is, the outer edge 17d of the negative electrode 17 is located inside compared to the outer edge 15d of the electrode plate 15. The positive electrode 16 is one size smaller than the negative electrode 17. That is, the outer edge 16d of the positive electrode 16 is located inside compared to the outer edge 17d of the negative electrode 17. In addition, the inner side refers to the center side of the storage module 4 when viewed from the stacking direction D. The outer side refers to the side away from the center of the storage module 4 when viewed from the stacking direction D.

[0051] The first resin portion 21 is in the shape of a rectangular frame when viewed from the stacking direction D, and is continuously provided over the entire circumference of the peripheral portion 15c of each of the bipolar electrode 14, the negative terminal electrode 18, and the positive terminal electrode 19. The first resin portion 21 is a film having a predetermined thickness (length in the stacking direction D). The first resin portion 21 includes an inner edge 21c and an outer edge 21d, both of which are rectangular when viewed from the stacking direction D. The first resin portion 21 is fused to the surfaces of the bipolar electrode 14, the negative terminal electrode 18, and the positive terminal electrode 19 at least at the peripheral portion 15c of each of the bipolar electrode 14, the negative terminal electrode 18, and the positive terminal electrode 19. Specifically, the first resin portion 21 is fused to the first surface 15a and the end surface of each of the bipolar electrode 14, the negative terminal electrode 18, and the positive terminal electrode 19 to be airtightly (liquid-tightly) joined thereto.

[0052] The outer edge 21d of the first resin portion 21 is located outside the outer edge 15d of the electrode plate 15. The inner edge 21c of the first resin portion 21 is located between the outer edge 15d of the electrode plate 15 and the outer edge 17d of the negative electrode 17. A step portion 21e is formed in the first resin portion 21 welded to the bipolar electrode 14 and the positive terminal electrode 19. The step portion 21e is formed on the inner edge 21c side, which is the side opposite to the electrode of the first resin portion 21. The edge of the separator 13 is placed on the step portion 21e.

[0053] The outer edges 15d of the electrode plates 15 of the bipolar electrode 14, the negative terminal electrode 18, and the positive terminal electrode 19 are aligned with each other. The outer edges 17d of the negative electrodes 17 of the bipolar electrode 14 and the negative terminal electrode 18 are aligned with each other. The outer edges 16d of the positive electrodes 16 of the bipolar electrode 14 and the positive terminal electrode 19 are aligned with each other. The inner edges 21c of the plurality of first resin portions 21 are aligned with each other. The outer edges 21d of the plurality of first resin portions 21 are aligned with each other.

[0054] The reinforcing body 23 is provided on the electrode (here, the negative terminal electrode 18 and the positive terminal electrode 19) to suppress deformation of the electrode. The reinforcing body 23 includes a first reinforcing portion 24 and a second reinforcing portion 25. The first reinforcing portion 24 is joined to the second surface 15b of the negative terminal electrode 18 at the peripheral portion 15c of the negative terminal electrode 18. The first reinforcing portion 24 is welded to the second surface 15b of the negative terminal electrode 18. The first reinforcing portion 24 is a film having a predetermined thickness (length in the stacking direction D).

[0055] The first reinforcing portion 24 is in a rectangular frame shape when viewed from the stacking direction D, and is continuously provided over the entire circumference of the peripheral edge portion 15c of the negative terminal electrode 18. The first reinforcing portion 24 includes an inner edge 24c and an outer edge 24d, both of which are rectangular when viewed from the stacking direction D. The inner edge 24c of the first reinforcing portion 24 coincides with the inner edge 21c of the first resin portion 21 when viewed from the stacking direction D. The outer edge 24d of the first reinforcing portion 24 coincides with the outer edge 21d of the first resin portion 21 when viewed from the stacking direction D. The negative terminal electrode 18 is sandwiched between the first resin portion 21 and the first reinforcing portion 24.

[0056] The second reinforcing portion 25 is joined to the second surface 15b of the positive terminal electrode 19 at the peripheral portion 15c of the positive terminal electrode 19. The second reinforcing portion 25 is welded to the second surface 15b of the positive terminal electrode 19. The second reinforcing portion 25 is the same as the first reinforcing portion 24. That is, the second reinforcing portion 25 is a film having a predetermined thickness (length in the stacking direction D).

[0057] The second reinforcing portion 25 is in a rectangular frame shape when viewed from the stacking direction D, and is continuously provided over the entire circumference of the peripheral edge portion 15c of the positive terminal electrode 19. The second reinforcing portion 25 includes an inner edge 25c and an outer edge 25d, both of which are rectangular when viewed from the stacking direction D. The inner edge 25c of the second reinforcing portion 25 coincides with the inner edge 21c of the first resin portion 21 when viewed from the stacking direction D. The outer edge 25d of the second reinforcing portion 25 coincides with the outer edge 21d of the first resin portion 21 when viewed from the stacking direction D. The positive terminal electrode 19 is sandwiched between the first resin portion 21 and the second reinforcing portion 25.

[0058] The first resin portion 21, the first reinforcement portion 24, and the second reinforcement portion 25 are respectively bonded to the electrode plate 15 by, for example, ultrasonic or thermal fusion. The inner end portions of the first resin portion 21, the first reinforcement portion 24, and the second reinforcement portion 25 are respectively located between the peripheral edge portions 15c of the electrode plates 15 adjacent to each other in the stacking direction D, and the outer end portions extend outward from the electrode plates 15 when viewed from the stacking direction D. The first resin portion 21, the first reinforcement portion 24, and the second reinforcement portion 25 are respectively embedded in the second resin portion 22 in the outer end portions. The first resin portions 21 adjacent to each other along the stacking direction D are separated from each other.

[0059] The second resin portion 22 is provided outside the electrode stack 11, the first resin portion 21, the first reinforcement portion 24, and the second reinforcement portion 25, and constitutes the outer wall (box) of the power storage module 4. The second resin portion 22 is formed, for example, by injection molding of a resin, and extends over the entire length of the electrode stack 11 along the stacking direction D. The second resin portion 22 is in a cylindrical (ring-shaped) shape extending in the stacking direction D as an axial direction. The second resin portion 22 is fused (bonded) to the outer surfaces of the first resin portion 21, the first reinforcement portion 24, and the second reinforcement portion 25, for example, by heat during injection molding. The first reinforcement portion 24 and the second reinforcement portion 25 are surrounded by the second resin portion 22 together with the first resin portion 21, and bonded to the second resin portion 22.

[0060] The second resin portion 22, together with the first resin portion 21, seals the bipolar electrodes 14 adjacent to each other along the stacking direction D, the negative terminal electrode 18 and the bipolar electrode 14 adjacent to each other along the stacking direction D, and the positive terminal electrode 19 and the bipolar electrode 14 adjacent to each other along the stacking direction D. Thus, an internal space V separated by airtightness (liquidtightness) is 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. An electrolyte (not shown) such as an alkaline aqueous solution such as an aqueous potassium hydroxide solution is contained in the internal space V. That is, the sealing body 12 having the first resin portion 21 and the second resin portion 22 forms the internal space V for containing the electrolyte between the electrodes adjacent to each other along the stacking direction D, and seals the internal space V. The electrolyte is impregnated into the separator 13, the positive electrode 16, and the negative electrode 17.

[0061] The first reinforcement 24 and the second reinforcement 25 (reinforcement body 23 (hereinafter the same)) include, for example, resin. The tensile strength of the material of each of the first reinforcement 24 and the second reinforcement 25 is greater than the tensile strength of the material of the first resin part 21 and the second resin part 22. The Young's modulus of the material of each of the first reinforcement 24 and the second reinforcement 25 is greater than the Young's modulus of the material of the first resin part 21 and the second resin part 22. The material of each of the first resin part 21, the second resin part 22, the first reinforcement 24, and the second reinforcement 25 is, for example, polypropylene (PP). The material of each of the first resin part 21, the second resin part 22, the first reinforcement 24, and the second reinforcement 25 is, for example, oriented polypropylene (OPP). The material of each of the first resin part 21, the second resin part 22, the first reinforcement 24, and the second reinforcement 25 is, for example, biaxially oriented polypropylene. Alternatively, the material of each of the first resin portion 21, the second resin portion 22, the first reinforcement portion 24, and the second reinforcement portion 25 is, for example, unstretched polypropylene (CPP: Cast Polypropylene). The tensile strength and Young's modulus are measured by the method specified in JIS K 7127, for example.

[0062] Next, the operation and effects of the power storage module 4 will be described. Figure 6 This is an enlarged cross-sectional view of a main part showing the state of the negative terminal electrode when the internal pressure in the electricity storage module of the comparative example increases. Figure 7 1 is an enlarged cross-sectional view of a main part showing the state of the positive terminal electrode when the internal pressure in the storage module of the comparative example increases. Figure 6 and Figure 7 As shown, the power storage module 100 of the comparative example is different from the power storage module 4 of the embodiment in that it does not include the first reinforcement portion 24 and the second reinforcement portion 25 .

[0063] In the power storage module 100, when the internal pressure of the bipolar electrode 114 or the internal space V between the bipolar electrodes 114 increases due to the use conditions, the load caused by the internal pressure of the internal space V adjacent in the stacking direction is eliminated in the middle layer of the electrode stack 111. In addition, since the internal space V itself is also a very small space, the bipolar electrode 114 is less likely to be deformed.

[0064] On the other hand, in the negative terminal electrode 118 and the positive terminal electrode 119 located at the stacking end of the electrode stack 111, unlike the intermediate layer, the load due to the internal pressure of the internal space V is not eliminated. Therefore, it is conceivable that when the internal pressure increases, the negative terminal electrode 118 and the positive terminal electrode 119 are deformed outward in the stacking direction. If the negative terminal electrode 118 and the positive terminal electrode 119 are deformed, excessive stress may be applied to the first resin portion 121, causing the first resin portion 121 to break or a gap to be generated between the first resin portion 121 and the negative terminal electrode 118 and the positive terminal electrode 119. The breakage of the first resin portion 121 or the formation of a gap between the first resin portion 121 and the negative terminal electrode 118 and the positive terminal electrode 119 may cause the electrolyte (not shown) to leak to the outside of the electrode stack 111.

[0065] In this regard, in the power storage module 4, the electrode includes: a plurality of bipolar electrodes 14; and a negative terminal electrode 18 disposed at one end in the stacking direction D of the electrode stack 11. The sealing body 12 includes: a plurality of first resin portions 21 fused to the first surface 15a of the electrode at the peripheral edge portion 15c of the electrode; and a second resin portion 22 joined to the first resin portion 21 so as to surround the plurality of first resin portions 21 from the outside in the stacking direction D. The reinforcing body 23 includes a first reinforcing portion 24 joined to the second surface 15b of the negative terminal electrode 18. Thus, in the bipolar electrode 14, the first resin portion 21 is fused to the first surface 15a, and in the negative terminal electrode 18, the first resin portion 21 is fused to the first surface 15a, and the first reinforcing portion 24 is joined to the second surface 15b. Therefore, for example, when the internal pressure of the internal space V increases, deformation of the negative terminal electrode 18 is suppressed, and leakage of electrolyte or damage (for example, damage to the first resin portion 21 ) on the negative terminal electrode 18 side is suppressed. Therefore, the power storage module 4 can improve reliability.

[0066] In addition, in the power storage module 100, due to the so-called alkali creep phenomenon, the electrolyte sometimes diffuses on the electrode plate of the negative terminal electrode 118, passes through the gap between the first resin portion 121 of the seal and the electrode plate, and seeps out to the outside of the internal space V. This alkali creep phenomenon may occur when the power storage device is charged, discharged, and unloaded due to electrochemical factors and fluid phenomena. The alkali creep phenomenon is caused by the existence of channels for the negative electrode potential, moisture, and electrolyte. In response to this, in the power storage module 4, as described above, in the negative terminal electrode 18, the first resin portion 21 is fused to the first surface 15a, and the first reinforcement portion 24 is bonded to the second surface 15b. As a result, the electrolyte seepage path becomes longer, so that leakage of the electrolyte can be suppressed.

[0067] In the power storage module 4, the electrode includes a positive terminal electrode 19, which includes an electrode plate 15 and a positive electrode 16 provided on a first surface 15a, and is arranged at the other end of the electrode stack 11 in the stacking direction D so that the first surface 15a faces the inner side in the stacking direction D of the electrode stack 11. The reinforcing body 23 includes a second reinforcing portion 25 joined to the second surface 15b of the positive terminal electrode 19 at the peripheral portion 15c of the positive terminal electrode 19. In this way, in the bipolar electrode 14, the first resin portion 21 is fused to the first surface 15a, and in the positive terminal electrode 19, similarly to the negative terminal electrode 18 side, the first resin portion 21 is fused to the first surface 15a, and the second reinforcing portion 25 is joined to the second surface 15b. Therefore, deformation of the positive terminal electrode 19 is suppressed, and leakage of electrolyte or damage (for example, damage to the first resin portion 21 ) on the positive terminal electrode 19 side is suppressed. As a result, the reliability of the power storage module 4 is further improved.

[0068] In the power storage module 4, the first reinforcement 24 and the second reinforcement 25 are joined to the second resin portion 22 together with the first resin portion 21. Therefore, the first reinforcement 24 and the second reinforcement 25 can be used to seal the internal space V in addition to the first resin portion 21.

[0069] In addition, in the power storage module 4, the tensile strength of the material of the first reinforcement portion 24 and the second reinforcement portion 25 is greater than the tensile strength of the material of the first resin portion 21. As a result, the negative terminal electrode 18 and the positive terminal electrode 19 are further reliably reinforced by the first reinforcement portion 24 and the second reinforcement portion 25. Therefore, deformation of the negative terminal electrode 18 and the positive terminal electrode 19 can be further reliably suppressed.

[0070] In addition, in the power storage module 4, the Young's modulus of the material of the first reinforcement portion 24 and the second reinforcement portion 25 is larger than the Young's modulus of the material of the first resin portion 21. Thus, the negative terminal electrode 18 and the positive terminal electrode 19 are further reliably reinforced by the first reinforcement portion 24 and the second reinforcement portion 25. Therefore, deformation of the negative terminal electrode 18 and the positive terminal electrode 19 can be further reliably suppressed.

[0071] In addition, in the power storage module 4, when the material of the first reinforcement part 24 and the second reinforcement part 25 is any one of polypropylene, stretched polypropylene, and biaxially stretched polypropylene, the negative terminal electrode 18 and the positive terminal electrode 19 are further reliably reinforced by the first reinforcement part 24 and the second reinforcement part 25. Therefore, the deformation of the negative terminal electrode 18 and the positive terminal electrode 19 can be further reliably suppressed.

[0072] Although one embodiment has been described above, one aspect of the present invention is not limited to the above embodiment.

[0073] Figure 8 2 is a schematic cross-sectional view showing the internal structure of a power storage module according to a modified example. Figure 8 As shown, the second resin portion 22 includes an overlapping portion 26. Specifically, the overlapping portion 26 includes a first overlapping portion 27 provided at one end of the electrode stack 11 in a manner overlapping the negative terminal electrode 18 when viewed from the stacking direction D, and a second overlapping portion 28 provided at the other end of the electrode stack 11 in a manner overlapping the positive terminal electrode 19 when viewed from the stacking direction D.

[0074] The first overlapping portion 27 is formed in a rectangular ring shape when viewed from the stacking direction D, and overlaps the first resin portion 21, the electrode plate 15, and the first reinforcing portion 24 over the entire circumference of the peripheral portion 15c of the negative terminal electrode 18. The first overlapping portion 27 is welded to the surface of the first resin portion 21 on the side opposite to the negative terminal electrode 18 and is airtightly (liquid-tightly) joined to the first resin portion 21. The inner edge 27c of the first overlapping portion 27 coincides with the inner edge 21c of the first resin portion 21 and the inner edge 24c of the first reinforcing portion 24.

[0075] The second overlapping portion 28 is formed in a rectangular ring shape when viewed from the stacking direction D, and overlaps the first reinforcing portion 24, the electrode plate 15, and the first resin portion 21 over the entire circumference of the peripheral portion 15c of the positive terminal electrode 19. The second overlapping portion 28 is welded to the surface of the second reinforcing portion 25 on the side opposite to the positive terminal electrode 19 and is joined to the second reinforcing portion 25 in an airtight (liquid-tight) manner. The inner edge 28c of the second overlapping portion 28 coincides with the inner edge 25c of the second reinforcing portion 25 and the inner edge 21c of the first resin portion 21. According to this configuration, the negative terminal electrode 18 and the positive terminal electrode 19 are reinforced by the first overlapping portion 27 and the second overlapping portion 28, so that deformation of the negative terminal electrode 18 and the positive terminal electrode 19 can be further reliably suppressed.

[0076] In addition, the materials of the first resin part 21, the second resin part 22, the first reinforcing part 24, and the second reinforcing part 25 may be uniaxially stretched polypropylene. In this case, the negative terminal electrode 18 and the positive terminal electrode 19 are further reliably reinforced by the first reinforcing part 24 and the second reinforcing part 25, so that the deformation of the negative terminal electrode 18 and the positive terminal electrode 19 can be further reliably suppressed. In addition, the materials of the first resin part 21, the second resin part 22, the first reinforcing part 24, and the second reinforcing part 25 may be acid-modified polypropylene, modified polyphenylene ether, polypropylene, or a thermoplastic elastomer obtained by mixing a rubber component and polypropylene.

[0077] In addition, the material of the first reinforcement portion 24 and the second reinforcement portion 25 may be the same as the material of the first resin portion 21. In this case, the material can be made common.

[0078] In addition, although the example in which the inner edge 24c of the first reinforcing portion 24 coincides with the inner edge 21c of the first resin portion 21 is shown in the above embodiment, the inner edge 24c of the first reinforcing portion 24 may not coincide with the inner edge 21c of the first resin portion 21. The inner edge 24c of the first reinforcing portion 24 may, for example, be located at a position further inside than the inner edge 21c of the first resin portion 21. Similarly, the inner edge 25c of the second reinforcing portion 25 may not coincide with the inner edge 21c of the first resin portion 21. The inner edge 25c of the second reinforcing portion 25 may, for example, be located at a position further inside than the inner edge 21c of the first resin portion 21. In this case, the negative terminal electrode 18 and the positive terminal electrode 19 are further reliably reinforced by the first reinforcing portion 24 and the second reinforcing portion 25.

[0079] In addition, although the example in which the inner edges 21c of the plurality of first resin portions 21 coincide with each other is shown, the inner edge 21c of the first resin portion 21 welded to the negative terminal electrode 18 and the inner edge 21c of the first resin portion 21 welded to the positive terminal electrode 19 may be located, for example, at a position inside the outer edge 16d of the positive electrode 16 or the outer edge 17d of the negative electrode 17. In other words, the inner edge 21c of the first resin portion 21 welded to the negative terminal electrode 18 and the inner edge 21c of the first resin portion 21 welded to the positive terminal electrode 19 may extend so as to overlap with the positive electrode 16 or the negative electrode 17. In this case, the negative terminal electrode 18 and the positive terminal electrode 19 are further reliably reinforced by the first resin portion 21.

[0080] Furthermore, as described above, from the viewpoint of suppressing liquid leakage due to alkali creep, it is more important to provide the first reinforcing portion 24 to the negative terminal electrode 18. Therefore, from this viewpoint, the reinforcing body 23 may not include the second reinforcing portion 25.

[0081] Description of Reference Numerals

[0082] 4…power storage module, 11…electrode stack (stack), 12…sealing body, 14…bipolar electrode, 15…electrode plate, 15a…first surface, 15b…second surface, 15c…peripheral portion, 16…positive electrode, 17…negative electrode, 18…negative electrode terminal electrode, 19…positive electrode terminal electrode, 21…first resin portion (first sealing portion), 22…second resin portion (second sealing portion), 23…reinforcing body, 24…first reinforcing portion, 25…second reinforcing portion, 26…overlapping portion, 27…first overlapping portion, 28…second overlapping portion, D…stacking direction (first direction), V…internal space.

Claims

1. A power storage module, characterized in that: have: A stacked body comprising a plurality of electrodes stacked along a first direction; a sealing body provided on the stacked body so as to surround the peripheral edge of the electrode, forming an internal space for storing an electrolyte between the electrodes adjacent to each other in the first direction, and sealing the internal space; and A reinforcing body, which is provided on the electrode and is used to suppress deformation of the electrode. The electrodes include a plurality of bipolar electrodes and a negative terminal electrode. The bipolar electrode includes an electrode plate, a positive electrode disposed on a first surface of the electrode plate, and a negative electrode disposed on a second surface of the electrode plate opposite to the first surface. The negative terminal electrode includes the electrode plate and a negative electrode provided on the second surface, and is arranged at one end of the stack in the first direction with the second surface facing the inner side of the stack in the first direction. The sealing body includes: a plurality of first sealing portions which are welded to the first surface at the peripheral edge of the electrode; and a second sealing portion which is joined to the first sealing portion in a manner of surrounding the plurality of first sealing portions from the outside in the first direction. The reinforcing body includes a first reinforcing portion, and the first reinforcing portion is joined to the second surface of the negative terminal electrode at a peripheral portion of the negative terminal electrode.

2. The power storage module according to claim 1, The above-mentioned electrode further comprises a positive terminal electrode, The positive terminal electrode includes the electrode plate and the positive electrode provided on the first surface, and is arranged at the other end of the stack in the first direction in such a manner that the first surface faces the inner side of the stack in the first direction. The reinforcing body further includes a second reinforcing portion joined to the second surface of the positive terminal electrode at a peripheral portion of the positive terminal electrode.

3. The power storage module according to claim 1 or 2, The reinforcing body is joined to the second sealing portion together with the first sealing portion.

4. The power storage module according to claim 1 or 2, The second sealing portion includes an overlapping portion provided at one end and the other end of the stacked body so as to overlap with the electrode when viewed from the first direction.

5. The power storage module according to claim 1 or 2, The tensile strength of the material of the reinforcing body is greater than the tensile strength of the material of the first sealing portion.

6. The power storage module according to claim 1 or 2, The Young's modulus of the material of the reinforcing body is larger than the Young's modulus of the material of the first sealing portion.

7. The power storage module according to claim 1 or 2, The material of the reinforcement body is polypropylene.

8. The power storage module according to claim 7, The material of the reinforcement body is stretched polypropylene.

9. The power storage module according to claim 8, The material of the reinforcement is biaxially stretched polypropylene.

10. The power storage module according to claim 1 or 2, The material of the reinforcing body is the same as that of the first sealing portion.

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