阅读说明：本技术 蓄电模块 (Electricity storage module ) 是由 田丸耕二郎 酒井崇 山田正博 岸根翔 前田纮树 于 2020-03-10 设计创作，主要内容包括：在蓄电模块(4)中,电极层叠体(11)的侧面(11a)具有在层叠方向(D)上相邻的第1密封部(21)彼此熔接而成的熔接层(30)。密封体(12)具有：侧面(开口壁)(12A),其设置有与内部空间(V)连通的贯通孔(R)；以及侧面(非开口壁)(12B～12D),其未设置贯通孔(R)。在从层叠方向(D)观看时,开口壁处的熔接层(30)的宽度(W1)小于非开口壁处的熔接层(30)的宽度(W2)。(In the electricity storage module (4), the side surface (11a) of the electrode laminate (11) has a welded layer (30) in which the 1 st seal sections (21) adjacent to each other in the lamination direction (D) are welded to each other. The sealing body (12) has: a side surface (opening wall) (12A) provided with a through hole (R) communicating with the internal space (V); and side surfaces (non-opening walls) (12B-12D) which are not provided with the through holes (R). The width (W1) of the weld layer (30) at the opening wall is smaller than the width (W2) of the weld layer (30) at the non-opening wall when viewed from the stacking direction (D).)

1. An electricity storage module is provided with: an electrode laminate having a plurality of electrodes laminated in a 1 st direction; a separator accommodated in an internal space that contains an electrolyte and is formed between the adjacent electrodes in the electrode stack; and a sealing body provided at an outer peripheral portion of the electrode laminate and sealing the internal space,

the above-described power storage module is characterized in that,

the plurality of electrodes include a bipolar electrode having a positive electrode active material layer on one surface of a current collector and a negative electrode active material layer on the other surface of the current collector,

the sealing body comprises a 1 st sealing part and a 2 nd sealing part,

the 1 st sealing part is joined to an edge of the current collector of each of the plurality of electrodes and has a protruding part protruding outward from the edge of the current collector,

the 2 nd sealing part is provided on a side surface of the electrode laminate extending in the 1 st direction so as to cover an outer periphery of the 1 st sealing part,

the sealing body has a welded layer in which the protruding portions of the 1 st sealing portions adjacent to each other in the 1 st direction are welded to each other, and the sealing body has: an opening wall provided with a communication hole for communicating the internal space with the outside of the sealing body; and a non-opening wall provided with no communication hole,

the width of the welded layer at the opening wall is smaller than the width of the welded layer at the non-opening wall when viewed from the 1 st direction.

2. An electricity storage module is provided with: an electrode laminate having a plurality of electrodes laminated in a 1 st direction; a separator accommodated in an internal space that contains an electrolyte and is formed between the adjacent electrodes in the electrode stack; and a sealing body provided at an outer peripheral portion of the electrode laminate and sealing the internal space,

the above-described power storage module is characterized in that,

the plurality of electrodes include a bipolar electrode having a positive electrode active material layer on one surface of a current collector and a negative electrode active material layer on the other surface of the current collector,

the sealing body comprises a 1 st sealing part and a 2 nd sealing part,

the 1 st sealing part is joined to an edge of the current collector of each of the plurality of electrodes and has a protruding part protruding outward from the edge of the current collector,

the 2 nd sealing part is provided on a side surface of the electrode laminate extending in the 1 st direction so as to cover an outer periphery of the 1 st sealing part,

the sealing body has a welded layer in which the protruding portions of the 1 st sealing portions adjacent to each other in the 1 st direction are welded to each other, and the sealing body has: an opening wall provided with a communication hole for communicating the internal space with the outside of the sealing body; and a non-opening wall provided with no communication hole,

the fusion layer is provided on the non-opening wall but not on the opening wall.

3. The power storage module according to claim 1,

the opening wall is provided with: an opening region in which the communication hole is arranged; and a non-opening region where the communication hole is not provided,

the width of the welding layer in the non-opening region is larger than the width of the welding layer in the opening region when viewed from the 1 st direction.

Technical Field

The present disclosure relates to an electricity storage module.

Background

As a conventional electrical storage module, a bipolar battery including a bipolar electrode having a positive electrode formed on one surface of an electrode plate and a negative electrode formed on the other surface of the electrode plate is known (see patent document 1). The bipolar battery includes a laminate in which a plurality of bipolar electrodes are laminated with separators interposed therebetween. A sealing body for sealing between the bipolar electrodes adjacent to each other in the stacking direction is provided on the side surface of the stacked body. An electrolyte is contained in an internal space formed between the bipolar electrodes.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open publication No. 2011-204386

Disclosure of Invention

Problems to be solved by the invention

In order to accommodate the electrolyte in the bipolar battery as in patent document 1, an injection port for injecting the electrolyte into the battery needs to be formed in the sealing body. However, when a sealing body is formed to seal between adjacent bipolar electrodes and then an injection port is formed in the sealing body, the manufacturing process may be complicated. Further, if the position of the injection port is deviated from the design, the sealing performance of the sealing body may be deteriorated.

The present disclosure has been made to solve the above-described problems, and an object thereof is to provide an electricity storage module capable of sufficiently ensuring sealing performance of a sealing body without complicating a manufacturing process.

Means for solving the problems

An electric storage module according to an aspect of the present disclosure includes: an electrode laminate having a plurality of electrodes laminated in a 1 st direction; a separator received in an internal space that contains an electrolyte and is formed between adjacent electrodes in the electrode stack; and a sealing body that is provided at an outer peripheral portion of the electrode laminate and seals the internal space, wherein the plurality of electrodes include a bipolar electrode having a positive electrode active material layer on one surface of the current collector and a negative electrode active material layer on the other surface of the current collector, the sealing body includes a 1 st sealing portion and a 2 nd sealing portion, the 1 st sealing portion is joined to an edge portion of the current collector of each of the plurality of electrodes and has a protruding portion that protrudes outward from the edge portion of the current collector, the 2 nd sealing portion is provided at a side surface of the electrode laminate extending in the 1 st direction so as to cover an outer periphery of the 1 st sealing portion, the sealing body has a welding layer in which protruding portions of the 1 st sealing portion adjacent in the 1 st direction are welded to each other, and has: an opening wall provided with a communication hole for communicating the internal space with the outside of the sealing body; and a non-opening wall provided with no communicating hole, the width of the welding layer at the opening wall being smaller than the width of the welding layer at the non-opening wall when viewed from the 1 st direction.

In this electricity storage module, when viewed from the 1 st direction, the width of the weld layer at the opening wall of the through hole that connects the internal space to the outside of the sealing body is smaller than the width of the weld layer at the non-opening wall where the communication hole is not provided. The through-hole can be formed, for example, as follows: a plate member as a hole forming member is inserted into a through hole provided in a 1 st seal part, a 2 nd seal part is formed in this state, and then the plate member is pulled out from the seal body. In this case, since the position of the through hole can be defined by inserting the plate member, the formation position of the through hole can be prevented from deviating from the design. Further, since the width of the weld layer at the opening wall is small, when the projecting portions of the 1 st seal part are welded in advance, the fused portion of the 1 st seal part can be prevented from becoming a burr and adhering to the panel. Therefore, in this electricity storage module, the 2 nd sealing part can be formed without removing the plate member used when the projecting portions of the 1 st sealing part are welded in advance, and complication of the manufacturing process can be avoided. On the other hand, the width of the weld layer is sufficiently secured at the non-opening wall, and therefore, the sealing performance of the sealing body can be ensured.

An electric storage module according to an aspect of the present disclosure includes: an electrode laminate having a plurality of electrodes laminated in a 1 st direction; a separator received in an internal space that contains an electrolyte and is formed between adjacent electrodes in the electrode stack; and a sealing body that is provided at an outer peripheral portion of the electrode laminate and seals the internal space, wherein the plurality of electrodes include a bipolar electrode having a positive electrode active material layer on one surface of the current collector and a negative electrode active material layer on the other surface of the current collector, the sealing body includes a 1 st sealing portion and a 2 nd sealing portion, the 1 st sealing portion is joined to an edge portion of the current collector of each of the plurality of electrodes and has a protruding portion that protrudes outward from the edge portion of the current collector, the 2 nd sealing portion is provided at a side surface of the electrode laminate extending in the 1 st direction so as to cover an outer periphery of the 1 st sealing portion, the sealing body has a welding layer in which protruding portions of the 1 st sealing portion adjacent in the 1 st direction are welded to each other, and has: an opening wall provided with a communication hole for communicating the internal space with the outside of the sealing body; and a non-opening wall provided with no communication hole, the fusion-bonded layer being provided on the non-opening wall and not provided on the opening wall.

In this electricity storage module, the fusion-welded layer is provided on the non-opening wall where the communication hole for communicating the internal space with the outside of the sealing body is not provided, and the fusion-welded layer is not provided on the opening wall where the communication hole is provided. The through-hole can be formed, for example, as follows: a plate member as a hole forming member is inserted into a through hole provided in a 1 st seal part, a 2 nd seal part is formed in this state, and then the plate member is pulled out from the seal body. In this case, since the position of the through hole can be defined by inserting the plate member, the formation position of the through hole can be prevented from deviating from the design. Further, since the welding layer is not provided on the opening wall, when the projecting portions of the 1 st seal part are welded in advance, the fused portion of the 1 st seal part can be prevented from becoming a burr and adhering to the plate member. Therefore, in this electricity storage module, the 2 nd sealing part can be formed without removing the plate member used when the projecting portions of the 1 st sealing part are welded in advance, and complication of the manufacturing process can be avoided. On the other hand, since the welding layer is provided on the non-opening wall, the sealing performance of the sealing body can be ensured.

The opening wall may be provided with: an opening region in which a through-hole is arranged; and a non-opening region in which the through-hole is not disposed, wherein a width of the welding layer in the non-opening region is larger than a width of the welding layer in the opening region when viewed from the 1 st direction. In this case, when the electrode laminate is placed in the mold in forming the 2 nd seal part, the electrode laminate can be positioned in the mold with high accuracy by abutting the electrode laminate against a positioning block or the like in the non-opening region. Thus, the improvement of the dimensional accuracy of the 2 nd seal portion can be achieved. Further, by sufficiently welding the 1 st seal portion in the non-open region, the rigidity of the 1 st seal portion in the in-plane direction in the non-open region can be sufficiently improved as compared with the rigidity of the 1 st seal portion in the in-plane direction in the open region without changing the resin material.

Effects of the invention

According to the present disclosure, the sealing performance of the sealing body can be sufficiently ensured without complicating the manufacturing process.

Drawings

Fig. 1 is a schematic cross-sectional view illustrating a power storage device including the power storage module according to the present embodiment.

Fig. 2 is a schematic cross-sectional view showing an internal configuration of the power storage module.

Fig. 3 is a perspective view showing an external configuration of the power storage module.

Fig. 4 is an enlarged cross-sectional view of a main portion of the internal structure of the power storage module on the side surface side where the pressure regulating valve is disposed.

Fig. 5 (a) is an enlarged cross-sectional view showing a main portion of the internal configuration of the power storage module on the side surface side where the pressure regulating valve is not disposed, and (b) is an enlarged cross-sectional view showing a main portion of the internal configuration of the power storage module at a portion corresponding to the non-opening region.

Fig. 6 is a schematic plan view showing a configuration example for securing rigidity in the in-plane direction of the 1 st seal portion at a portion corresponding to a non-opening region.

Fig. 7 is a flowchart showing a manufacturing process of the power storage module.

Fig. 8 is a schematic cross-sectional view showing a state where the 1 st seal portion is welded in advance.

Fig. 9 is a schematic diagram showing how the electrode laminate is positioned in the mold.

Fig. 10 is a schematic cross-sectional view showing a modification of the internal configuration of the power storage module.

Fig. 11 is a schematic plan view showing a modification of the fusion-bonded layer.

Fig. 12 is a schematic plan view showing another modification of the fusion-bonded layer.

Detailed Description

Hereinafter, a preferred embodiment of the power storage module according to one aspect of the present disclosure will be described in detail with reference to the drawings.

Fig. 1 is a schematic cross-sectional view showing one embodiment of a power storage device. The power storage device 1 shown in fig. 1 is used as a battery for various vehicles such as a forklift, a hybrid vehicle, and an electric vehicle. The power storage device 1 includes: a module laminate 2 including a plurality of stacked power storage modules 4; and a restraint member 3 that applies a restraint load to the module laminated body 2 in a lamination direction (1 st direction) D of the module laminated body 2.

The module stacked body 2 includes a plurality of (here, 3) power storage modules 4 and a plurality of (here, 4) conductive plates 5. The conductive plate 5 is made of a metal material having high conductivity such as aluminum or iron or a conductive resin. Power storage module 4 is a bipolar battery and has a rectangular shape when viewed from stacking direction D. The storage module 4 is a secondary battery such as a nickel-metal hydride secondary battery or a lithium ion secondary battery, or an electric double layer capacitor. In the following description, a nickel-hydrogen secondary battery is exemplified.

The power 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 disposed between the power storage modules 4 adjacent to each other in the stacking direction D and outside the power storage modules 4 located at the stacking ends, respectively. A positive electrode terminal 6 is connected to one conductive plate 5 disposed outside the power storage module 4 located at the lamination end. The negative terminal 7 is connected to the other conductive plate 5 disposed outside the power storage module 4 located at the lamination end. The positive electrode terminal 6 and the negative electrode terminal 7 are drawn out from the edge of the conductive plate 5, for example, in a direction intersecting the stacking direction D. The charge and discharge of the power storage device 1 are performed by the positive electrode terminal 6 and the negative electrode terminal 7. In power storage device 1, power storage module 4 may be disposed at one end and the other end in stacking direction D. That is, the outermost layer (stack outermost layer) of the stack of the power storage modules 4 and the conductive plates 5 in the module stack 2 may be the power storage module 4. In this case, the positive electrode terminal 6 and the negative electrode terminal 7 are provided for the electricity storage module 4 at the outermost layer of the stack.

The conductive plate 5 is provided with a plurality of flow paths 5a through which a cooling fluid such as cooling water or cooling air flows. The flow path 5a extends, for example, in a direction intersecting (orthogonal to) the stacking direction D and the drawing direction of the positive electrode terminal 6 and the negative electrode terminal 7. The conductive plates 5 have a function as a connecting member for electrically connecting the power storage modules 4 to each other, and also have a function as a heat dissipating plate for dissipating heat generated in the power storage modules 4 by flowing a cooling fluid through the flow passages 5 a. In the example of fig. 1, the area of the conductive plates 5 as viewed in the stacking direction D is smaller than the area of the power storage module 4, but the area of the conductive plates 5 may be the same as the area of the power storage module 4 or may be larger than the area of the power storage module 4 in view of improving heat dissipation.

The restraint member 3 is composed of a pair of end plates 8 that sandwich the module stacked body 2 in the stacking direction D, and a fastening bolt 9 and a nut 10 that fasten the end plates 8 to each other. The end plate 8 is a rectangular plate-shaped member having an area slightly larger than the areas of the power storage modules 4 and the conductive plates 5 when viewed in the stacking direction D. The end plate 8 is formed of, for example, a highly rigid metal material or a resin material that can withstand a restraining load. When the end plate 8 is formed of a metal material, an insulating member F having electrical insulation is provided on the surface of the end plate 8 on the module laminate 2 side. The insulating member F is made of, for example, an insulating resin formed in a film shape or a plate shape. By disposing such an insulating member F, the end plate 8 and the conductive plate 5 are insulated from each other. In the case where the outermost layer of the stack is the power storage module 4, the insulating member F is disposed between the restraining member 3 and the power storage module 4.

An insertion hole 8a is provided in the edge of the end plate 8 at a position outside the module laminate 2. The fastening bolt 9 is inserted from the insertion hole 8a of the one end plate 8 toward the insertion hole 8a of the other end plate 8, and a nut 10 is screwed to the tip end portion of the fastening bolt 9 protruding from the insertion hole 8a of the other end plate 8. Accordingly, the electricity storage modules 4 and the conductive plates 5 are sandwiched by the end plates 8 and unitized as the module stacked body 2, and the module stacked body 2 is applied with a restraining load in the stacking direction D.

Next, the structure of the power storage module 4 will be described in detail. Fig. 2 is a schematic cross-sectional view showing an internal configuration of the power storage module shown in fig. 1. As shown in fig. 2, the power storage module 4 includes an electrode laminate 11 and a resin seal body 12 for sealing the electrode laminate 11. The electrode stack 11 is composed of a plurality of electrodes stacked in the stacking direction D of the power storage module 4 with spacers 13 interposed therebetween. These electrodes comprise: a laminate of a plurality of bipolar electrodes 14; a negative terminal electrode 18; and a positive terminal electrode 19.

The bipolar electrode 14 includes an electrode plate (current collector) 15 including a 1 st surface 15a facing one side in the stacking direction D and a 2 nd surface 15b facing the opposite side to the stacking direction D. A positive electrode 16 is provided on the 1 st surface 15a, which is one surface of the electrode plate 15, and a negative electrode 17 is provided on the 2 nd surface 15b, which is the other surface of the electrode plate 15. The positive electrode 16 includes a positive electrode active material layer provided on the 1 st surface 15a of the electrode plate 15. The negative electrode 17 includes a negative electrode active material layer provided on the 2 nd surface 15b of the electrode plate 15. In the electrode laminate 11, the positive electrode 16 of one bipolar electrode 14 faces the negative electrode 17 of another bipolar electrode 14 adjacent to the other bipolar electrode in the lamination direction D via the separator 13. In the electrode laminate 11, the negative electrode 17 of one bipolar electrode 14 faces the positive electrode 16 of another bipolar electrode 14 adjacent to the other bipolar electrode in the lamination direction D via the separator 13.

The negative electrode terminal electrode 18 has an electrode plate 15 and a negative electrode 17 including a negative electrode active material layer provided on one surface of the electrode plate 15. In the present embodiment, no active material layer is formed on the 1 st surface 15a of the electrode plate 15 of the negative electrode terminal electrode 18, and the negative electrode 17 including the negative electrode active material layer is provided on the 2 nd surface 15 b. The negative electrode terminal electrode 18 is disposed at one end of the electrode laminate 11 in the lamination direction D so that the negative electrode 17 provided on one surface of the electrode plate 15 faces the positive electrode 16 of the bipolar electrode 14 adjacent to the electrode laminate in the lamination direction D through the separator 13. The 1 st surface 15a of the electrode plate 15 of the negative electrode terminal electrode 18 on which the active material layer is not provided constitutes one external terminal surface in the stacking direction D of the electrode laminate 11, and is electrically connected to one conductive plate 5 (see fig. 1) adjacent to the power storage module 4.

The positive electrode terminal electrode 19 includes an electrode plate 15 and a positive electrode 16 including a positive electrode active material layer provided on one surface of the electrode plate 15. In the present embodiment, the positive electrode 16 including the positive electrode active material layer is provided on the 1 st surface 15a of the electrode plate 15 of the positive electrode terminal electrode 19, and the active material layer is not formed on the 2 nd surface 15 b. The positive electrode terminal electrode 19 is disposed at the other end of the electrode laminate 11 in the lamination direction D so that the positive electrode 16 provided on one surface of the electrode plate 15 faces the negative electrode 17 of the bipolar electrode 14 adjacent to the positive electrode terminal electrode in the lamination direction D through the separator 13. The 2 nd surface 15b of the electrode plate 15 of the positive electrode terminal electrode 19 on which the active material layer is not provided constitutes the other external terminal surface in the stacking direction D of the electrode laminate 11, and is electrically connected to the other conductive plate 5 (see fig. 1) adjacent to the power storage module 4.

As the electrode plate 15, for example, a metal foil or a metal plate such as a nickel foil, a nickel-plated steel foil, or a stainless steel foil can be used. In the present embodiment, a rectangular metal foil made of nickel is used as the electrode plate 15, for example. The edge 15c of the electrode plate 15 is provided with a rectangular frame-shaped uncoated region where the positive electrode active material and the negative electrode active material are not formed. Examples of the positive electrode active material constituting positive electrode 16 include nickel hydroxide. Examples of the negative electrode active material constituting the negative electrode 17 include a hydrogen storage alloy. In the present embodiment, the formation area of the negative electrode 17 on the 2 nd surface 15b of the electrode plate 15 is one larger than the formation area of the positive electrode 16 on the 1 st surface 15a of the electrode plate 15.

The spacer 13 is formed in a sheet shape, for example. Examples of the separator 13 include a porous film made of polyolefin resin such as Polyethylene (PE) and polypropylene (PP); woven or nonwoven fabrics comprising polypropylene, methyl cellulose and the like. The separator 13 may be a separator reinforced with a vinylidene fluoride resin compound.

The sealing body 12 is a member that prevents a short circuit of liquid due to leakage of the electrolytic solution and prevents adjacent bipolar electrodes 14 from contacting each other and causing a short circuit. As the sealing body 12 in the alkaline battery, for example, an insulating resin having alkali resistance is used. The sealing body 12 covers the edge portions 15c of the electrode plates 15 stacked in the stacking direction D, and also functions as a case for holding the electrode stacked body 11. The seal body 12 holds the edge portion 15c on the side surface 11 a. The sealing body 12 has a 1 st sealing portion 21, and the 1 st sealing portion 21 is provided along the edge portion 15c of the electrode plate 15 so as to surround the active material layers (positive electrode active material layer and negative electrode active material layer) formed at the center of the electrode plate 15. The sealing body 12 has the 2 nd sealing part 22, and the 2 nd sealing part 22 surrounds the 1 st sealing part 21 from the outside along the side surface 11a of the electrode laminate 11 and is joined to each of the 1 st sealing parts 21. Examples of the material of the 1 st seal part 21 and the 2 nd seal part 22 include polypropylene (PP), Polyphenylene Sulfide (PPs), modified polyphenylene ether (modified PPE), and the like.

The 1 st sealing portion 21 is provided continuously over the entire periphery of the uncoated region of the edge portion 15c on the 1 st surface 15a of the rectangular electrode plate 15, and has a rectangular frame shape when viewed in the stacking direction D. In the present embodiment, the 1 st sealing portion 21 is provided not only for the electrode plate 15 of the bipolar electrode 14, but also for the electrode plate 15 of the negative terminal electrode 18 and the electrode plate 15 of the positive terminal electrode 19. The negative electrode terminal 18 has a 1 st sealing portion 21 provided at an edge portion 15c of the 1 st surface 15a of the electrode plate 15, and the positive electrode terminal 19 has a 1 st sealing portion 21 provided at an edge portion 15c of both the 1 st surface 15a and the 2 nd surface 15b of the electrode plate 15.

The 1 st sealing portion 21 is hermetically joined (welded) to the 1 st surface 15a of the electrode plate 15 by, for example, thermal welding or ultrasonic welding. The 1 st seal part 21 is, for example, a film having a predetermined thickness in the lamination direction D. In the 1 st seal portion 21, the inner portions that engage with the edge portions 15c of the electrode plates 15 are located between the edge portions 15c of the electrode plates 15 that are adjacent to each other in the stacking direction D. In the 1 st sealing portion 21, an outer portion not joined to the edge portion 15c of the electrode plate 15 becomes a protruding portion protruding outward from the edge of the electrode plate 15. The projection is engaged with the 2 nd seal 22. The projecting portions of the 1 st seal portions 21 adjacent in the stacking direction D are joined (welded) to each other by, for example, hot plate welding or the like.

The region where the electrode plate 15 overlaps the 1 st sealing portion 21 becomes a joint region of the electrode plate 15 and the 1 st sealing portion 21. In the bonding region, the surface of the electrode plate 15 is roughened. The roughened region may be only the bonding region, but in the present embodiment, the entire surface of the electrode plate 15 is roughened. The roughening can be achieved by forming a plurality of protrusions by, for example, electrolytic plating. By forming the plurality of projections, the resin in a molten state enters between the plurality of projections formed by roughening at the joint interface between the electrode plate 15 and the 1 st sealing portion 21, and an anchor effect is exerted. This can improve the bonding strength between the electrode plate 15 and the 1 st sealing portion 21. The protrusions formed during the roughening are, for example, overhang-shaped fine protrusions having a base end of a convex portion formed on the surface of the electrode plate 15. By forming such minute protrusions, the anchoring effect can be improved.

The 2 nd sealing part 22 is provided outside the electrode laminate 11 and the 1 st sealing part 21. The 2 nd sealing part 22 is formed by, for example, injection molding of a resin in a state where the electrode laminate 11 provided with the 1 st sealing part 21 is disposed as an insert in a mold, and extends over the entire length of the electrode laminate 11 along the lamination direction D. The 2 nd seal part 22 has a rectangular tubular shape extending in the axial direction in the stacking direction D. The 2 nd seal part 22 is welded to the outer edge portion of the 1 st seal part 21 by, for example, heat at the time of injection molding.

The 1 st sealing part 21 and the 2 nd sealing part 22 form an internal space V between adjacent electrodes and seal the internal space V. More specifically, the 2 nd sealing part 22 and the 1 st sealing part 21 respectively seal between the bipolar electrodes 14 adjacent to each other in the stacking direction D, between the negative electrode terminal electrode 18 and the bipolar electrode 14 adjacent to each other in the stacking direction D, and between the positive electrode terminal electrode 19 and the bipolar electrode 14 adjacent to each other in the stacking direction D. Accordingly, air-tightly partitioned internal spaces V are formed between the adjacent 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, respectively. The internal space V contains, for example, an alkaline solution such as a potassium hydroxide aqueous solution or a gel electrolyte for holding an electrolytic solution in a polymer. An electrolyte such as an electrolytic solution or a gel electrolyte is impregnated in the separator 13, the positive electrode 16, and the negative electrode 17.

Fig. 3 is a perspective view showing an external configuration of the power storage module. As shown in the drawing, the outer wall portion of the power storage module 4 is constituted by the sealing body 12. The sealing body 12 has 4 side surfaces 12A to 12D corresponding to the side surface 11a (see fig. 2) of the electrode laminate 11. Each of the side surfaces 12A to 12D is a surface extending along the stacking direction D of the electrode stack 11. In the example of fig. 3, the shape of the power storage module 4 when viewed from the stacking direction D is rectangular. The side surfaces 12A and 12B are short-side surfaces when viewed from the stacking direction D, and the side surfaces 12C and 12D are long-side surfaces when viewed from the stacking direction D.

A plurality of (4 in this case) pressure regulating valves 28 are provided at predetermined intervals on the side surface 12A among the side surfaces 12A to 12D. The pressure regulating valve 28 is a valve that releases the gas in the internal space V to the outside of the power storage module 4 to regulate the pressure in the internal space V. On the side surface 12A provided with the pressure regulating valve 28, as shown in fig. 4, the pressure regulating valve 28 and the through hole R communicating with the internal space V are provided in the seal body 12. That is, the side face 12A of the seal body 12 is formed of an opening wall provided with the through-hole R, and the side faces 12B to 12D of the seal body 12 are formed of non-opening walls not provided with the through-hole R. In fig. 4, the pressure regulating valve 28 is omitted.

The through-hole R is composed of, for example, a through-hole Ra provided in the 1 st seal part 21 and a through-hole Rb provided in the 2 nd seal part 22 corresponding to the through-hole Ra. The through-hole R is formed, for example, as follows: a plate 35 (see fig. 8) as a hole forming member is inserted in advance into the through hole Ra of the 1 st sealing part 21 provided in the electrode laminate 11 at the time of injection molding of the 2 nd sealing part 22, and the plate 35 is pulled out from the sealing body 12 after the 2 nd sealing part 22 is molded. The through-holes R also function as injection ports for injecting the electrolyte into the internal space V in the manufacturing process of the power storage module 4. After the electrolyte is injected, the through hole R is sealed. In the present embodiment, the opening region 31 in which the through hole R (in which the pressure regulating valve 28 is arranged) is disposed and the non-opening region 32 in which the through hole R (in which the pressure regulating valve 28 is not disposed) is not disposed are alternately provided in the side surface 12A (see fig. 3).

The seal body 12 has a weld layer 30, and the weld layer 30 is formed by welding the 1 st seal portions 21 adjacent to each other in the stacking direction D by hot plate welding or the like. The width W of fusion-spliced layer 30 when viewed from the stacking direction D differs between the side 12A where through-holes R are provided and the sides 12B to 12D where through-holes R are not provided. Specifically, in the present embodiment, as shown in fig. 4, the 1 st seal part 21 has a step part 29 on which the separator 13 is placed. The step portion 29 is formed by, for example, folding back the outer edge portion of the 1 st sealing portion 21 toward the inner edge side in the manufacturing process of the power storage module 4. Here, the width W of the fusion-bonded layer 30 is the length of a fused and solidified portion formed on the outer edge side (2 nd sealing part 22 side) of the 1 st sealing part 21 by hot plate fusion bonding. In the case of performing hot plate welding, the projecting length of the outer edge portion of the 1 st sealing portion 21 from the edge of the electrode plate 15 is reduced by melting of the resin material. Therefore, the width W of the fusion-bonded layer 30 is the length of the melt-solidified portion from the outer edge of the 1 st seal part 21 after hot plate fusion bonding is performed until the protrusion length of the outer edge portion of the 1 st seal part 21 becomes a fixed dimension from the initial value.

In the present embodiment, the width W1 (see fig. 4) of the fusion-spliced layer 30 on the side surface 12A is smaller than the width W2 (see fig. 5 a) of the fusion-spliced layer 30 on the side surfaces 12B to 12D. When the width W2 is 0.5mm to 1.0mm, the width W1 is set to 0.2mm or less, for example. The widths W1 and W2 can be adjusted according to conditions such as a welding temperature and a welding time in hot plate welding. The fusion-spliced layer 30 may be provided only on the side surfaces 12B to 12D not including the opening wall, and may not be provided on the side surface a including the opening wall. That is, the edge of the 1 st seal part 21 on the side surface 12A side may not be subjected to hot plate welding, and the width W1 of the welding layer 30 may be 0 mm.

At the edge of the 1 st seal part 21 on the side surface 12A side, the rigidity in the in-plane direction of the portion corresponding to the non-opening region 32 where the through-hole R is not arranged may be higher than the rigidity in the in-plane direction of the portion corresponding to the opening region 31 where the through-hole R is arranged. In the present embodiment, the rigidity in the in-plane direction is adjusted by adjusting the width W of the fusion-bonded layer 30. More specifically, in the present embodiment, the width W3 (see fig. 5 b) of the fusion-bonded layer 30 in the portion corresponding to the non-open region 32 is larger than the width W1 of the fusion-bonded layer 30 corresponding to the open region 31. The width W3 of the fusion-spliced layer 30 may be equal to the width of the fusion-spliced layer 30 of the side surfaces 12B to 12D, or may be a value between the width W1 and the width W2.

In the case of adjusting the rigidity in the in-plane direction by adjusting the width W of the fusion-bonded layer 30, a melting margin of the 1 st seal part 21 is required. For example, as shown in fig. 6 (a), in the 1 st seal part 21 before hot plate welding, a projected portion 33 may be provided as a melting margin at a position corresponding to the non-opening region 32. Thus, the resin of the protruding portion 33 can be made to firmly enter between the 1 st seal portions 21 adjacent in the stacking direction D. Therefore, the rigidity of the portion corresponding to the non-opening region 32 can be sufficiently ensured.

Instead of providing the projecting portion 33, for example, as shown in fig. 6 (b), a recessed portion 34 formed by hot plate welding may be provided at a position corresponding to the non-opening region 32 in the 1 st seal portion 21 after hot plate welding. By melting more resin in the recessed portion 34 than in other portions, the resin can be firmly inserted between the 1 st seal portions 21 adjacent to each other in the stacking direction D, as in the case of fig. 6 (a). Therefore, the rigidity of the portion corresponding to the non-opening region 32 can be sufficiently ensured.

Next, the manufacturing process of the above-described power storage module 4 will be described. Fig. 7 is a flowchart showing a manufacturing process of the power storage module. As shown in the figure, the manufacturing process includes: a laminating step (step S01), a fusion-bond layer forming step (step S02), a 2 nd seal portion forming step (step S03), and an injecting step (step S04).

In the lamination step, the bipolar electrodes 14 are laminated with the separators 13 interposed therebetween to obtain a laminate. Further, a negative electrode terminal electrode 18 and a positive electrode terminal electrode 19 were laminated on each of the two laminated ends of the laminate of the bipolar electrode 14 via a separator 13, to obtain an electrode laminate 11. At the time of lamination, the first sealing portion 21 having a rectangular frame shape is bonded in advance to the edge portion 15c of the electrode plate 15 of each of the bipolar electrode 14, the negative terminal electrode 18, and the positive terminal electrode 19 by welding or the like. In the 1 st seal portion 21, a recess is provided from the inner edge to the outer edge on the side to be the side surface 12A, and a plate member 35 is disposed in the recess (see fig. 8). The depth of the recess is, for example, the same as the thickness of the folded-back portion of the 1 st seal part 21 (the thickness of the upper portion of the step portion 29). The plate 35 is made of, for example, a metal plate. The number of the plate members 35 arranged is the same as the number of the internal spaces V formed in the electrode laminated body 11.

In the fusion-bonding layer forming step, as shown in fig. 8, the outer edge portions of the 1 st seal part 21 adjacent in the stacking direction D are fused to each other by the hot plate 36 on the side surface 11a of the electrode laminate 11. In fig. 8, the welding of the surfaces corresponding to the side surfaces 12A is shown, but the welding by the hot plate 36 is performed for each of the surfaces corresponding to the side surfaces 12A to 12D. At this time, by adjusting the welding temperature using hot plate 36 and the welding time using hot plate 36, width W1 of welding layer 30 on side surface 12A is made smaller than width W2 of welding layer 30 on side surfaces 12B to 12D (see fig. 4 and fig. 5 (a)). The width W3 of the fusion-bonded layer 30 at the portion corresponding to the non-open region 32 is made larger than the width (i.e., the width W1) of the fusion-bonded layer 30 at the portion corresponding to the open region 31 (see fig. 4 and 5 (b)).

In the 2 nd sealing portion forming step, the 2 nd sealing portion 22 is formed using, for example, an injection molding machine. Here, in a state where the plate 35 as the hole forming member is disposed in the through hole Ra of the 1 st sealing portion 21, the electrode laminate 11 in which the fusion-bonded layer 30 is formed in the 1 st sealing portion 21 is disposed in the mold 41 for injection molding. When the electrode laminate 11 is placed in the mold 41, the electrode laminate 11 is positioned using a positioning block 42 placed in the mold 41, as shown in fig. 9, for example. In this case, the electrode laminate 11 is pushed into the mold 41 by the pusher 43 so that the edge of the 1 st sealing portion 21 on the side surface 12A and the edge of the 1 st sealing portion 21 on the side surface 12B abut against the positioning block 42, respectively. At the edge of the 1 st seal portion 21 on the side surface 12A side, only the portion corresponding to the non-opening region 32 is abutted against the positioning block 42. The positioning block 42 and the pusher 43 may be removed from the mold 41 before the injection molding of the resin.

After the positioning, a resin material is poured into a space in the mold 41 from a gate (not shown) of the mold 41, and the 2 nd sealing portion 22 is formed around the 1 st sealing portion 21. After the 2 nd sealing part 22 is formed, the plate member 35 is removed from the electrode laminate 11. Thus, the sealing body 12 having the through-hole R is formed on the side surface 12A side. Examples of the method of removing the plate 35 include pulling out, heating, and ultrasonic vibration.

In the injection step, the electrolyte is injected into the internal space V through the through-hole R of the sealing body 12. After the injection, pressure regulating valve 28 is fitted to through-hole R to seal internal space V, thereby obtaining power storage module 4.

As described above, in the power storage module 4, the width W1 of the fusion-bonded layer 30 on the side surface (opening wall) 12A side provided with the through-hole R communicating with the internal space V is smaller than the width W2 of the fusion-bonded layer 30 on the other side surfaces (non-opening walls) 12B to 12D side. The through-hole R can be formed, for example, as follows: after the plate member 35 as a hole forming member is inserted into the through hole Ra provided in the 1 st seal portion and the 2 nd seal portion 22 is formed in this state, the plate member 35 is pulled out from the seal body 12. In this case, since the position of the through hole R can be defined by inserting the plate member 35, the formation position of the through hole R can be prevented from deviating from the design. Further, since the width W1 of the weld layer 30 on the side surface 12A side is small, when the projecting portions of the 1 st seal part 21 are welded in advance, the fused portion of the 1 st seal part 21 can be prevented from becoming a burr and adhering to the plate member 35. Therefore, in the power storage module 4, the 2 nd sealing part 22 can be formed without removing the plate member 35 used for welding the protruding portions of the 1 st sealing part 21 in advance, and the complexity of the manufacturing process can be avoided. On the other hand, the width W2 of the fusion-spliced layer 30 is sufficiently ensured on the side surfaces 12B to 12D, and therefore, the sealing performance of the sealing body 12 can be sufficiently ensured.

In addition, in the case where the welding layer 30 is not provided on the side surface 12A as the opening wall, when the projecting portions of the 1 st seal part are welded in advance, the fused portion of the 1 st seal part 21 can be more reliably prevented from being a burr and adhering to the plate 35.

In addition, in the power storage module 4, the side surface 12A is provided with: an opening region 31 in which a through hole R is arranged; and a non-open region 32 in which the through holes R are not arranged, a width W3 of the fusion-spliced layer 30 in the non-open region 32 being larger than a width W1 of the fusion-spliced layer 30 in the open region 31 when viewed in the stacking direction D. In this case, the rigidity of the 1 st seal part 21 in the in-plane direction in the non-opening region 32 can be sufficiently improved as compared with the rigidity of the 1 st seal part 21 in the opening region 31 in the in-plane direction. When the electrode laminate 11 abuts against the positioning block 42 in the mold 41, if the rigidity of the edge of the 1 st seal part 21 in the in-plane direction is insufficient, the edge of the 1 st seal part 21 is likely to be deformed, and the positioning accuracy of the positioning block 42 cannot be sufficiently obtained. In contrast, in the power storage module 4, by increasing the rigidity in the non-opening region 32 and bringing only this region into contact with the positioning block 42, the electrode stacked body 11 can be accurately positioned in the mold 41. Thus, the improvement of the dimensional accuracy of the 2 nd seal part 22 can be achieved. In addition, by sufficiently melting the edge of the 1 st seal part 21 in the non-opening region 32, the rigidity of the 1 st seal part 21 in the in-plane direction in the non-opening region 32 can be sufficiently improved compared to the rigidity of the 1 st seal part 21 in the opening region 31 in the in-plane direction without changing the resin material.

The present disclosure is not limited to the above-described embodiments. For example, the internal configuration of the power storage module 4 is not limited to the configuration shown in fig. 2. Fig. 10 is a schematic cross-sectional view showing a modification of the internal configuration of the power storage module. In the example of fig. 10, in each bipolar electrode 14, the outer edge side of the frame-shaped 1 st sealing portion 21 joined to the edge portion 15c on the 1 st surface 15a side of the electrode plate 15 is folded inward. Accordingly, a step portion 23 for placing the edge portion of the spacer 13 is formed on the inner edge side of the 1 st seal portion 21. The step portion 23 may be formed by laminating a film constituting a lower step portion to a film constituting an upper step portion.

In the example of fig. 10, the terminal conductors 20 are laminated on the outer sides of the negative electrode terminal electrode 18 and the positive electrode terminal electrode 19 in the laminating direction. The terminal conductor 20 is a so-called uncoated conductive member in which the positive electrode active material and the negative electrode active material are not provided on both surfaces. The terminal conductor 20 is in contact with the external terminal surface of the negative terminal electrode 18 or the positive terminal electrode 19 facing thereto, and is electrically connected to each other. The terminal conductor 20 can be formed of a rectangular metal foil made of nickel, a nickel-plated steel foil, a stainless steel foil, or the like, for example, as in the electrode plate 15 of the bipolar electrode 14. The entire surface or a part of the surface of the terminal conductor 20 may be roughened.

Similarly to the electrode plate 15 of the bipolar electrode 14, the frame-shaped 1 st sealing portion 21A is joined to the edge portion 20c of the terminal conductor 20. The 1 st sealing portion 21A is folded inward on the outer edge side and joined to each of the 1 st surface 20a and the 2 nd surface 20b at the edge portion 20c of the terminal conductor 20. The 1 st sealing portion 21A joined to the 2 nd surface 20b of the terminal conductor 20 on the negative terminal electrode 18 side is also joined to the 1 st surface 15a of the electrode plate 15 of the negative terminal electrode 18. The thickness of the film constituting the 1 st sealing portion 21A may be different from the thickness of the film constituting the 1 st sealing portion 21. In this case, the joint of the terminal conductor 20 and the 1 st sealing portion 21A also functions as a member for adjusting the thickness of the electrode laminate 11 including the 1 st sealing portions 21 and 21A in the stacking direction D.

The outer edge portions of the 1 st seal parts 21, 21A are joined to each other by the weld layer 30. In this modification, as shown in fig. 11, the fusion-spliced layer 30 is provided only on the side surfaces 12B to 12D constituted by the non-opening walls. That is, the width W1 of the fusion-bonded layer 30 is 0mm at the edge of the 1 st seal part 21 on the side surface 12A side. Since the fusion-bonded layer 30 on the side surface 12A is not formed, the fused portion of the 1 st seal part 21 can be prevented from being attached to the plate member 35 as a burr (see fig. 8).

In the case where the formation of the weld layer 30 on the side face 12A side is not performed, the bipolar electrode 14 to which the 1 st seal portion 21 has been bonded in advance to the electrode plate 15, the negative electrode terminal electrode 18 to which the 1 st seal portion 21 has been bonded in advance to the electrode plate 15, the positive electrode terminal electrode 19 to which the 1 st seal portion 21 has been bonded in advance to the electrode plate 15, and the terminal conductor 20 to which the 1 st seal portion 21A has been bonded in advance are laminated in the laminating step with reference to the side corresponding to the side face 12A side to which the weld layer 30 is not formed. When the fusion-bonded layer 30 is formed on the side surface 12A side, if the number of burrs adhering to the plate member 35 is large, the burrs need to be removed before the 2 nd sealing portion forming step is performed. However, since the lamination accuracy of the side face 12A side which becomes the opening wall can be ensured by laminating the bipolar electrode 14, the negative electrode terminal electrode 18, the positive electrode terminal electrode 19, and the terminal conductor 20 with reference to the side corresponding to the side face 12A side on which the fusion-bonded layer 30 is not formed, it is not necessary to form the fusion-bonded layer 30 on the side face 12A side and to remove the burr adhered to the plate 35.

The fusion-bonded layer 30 may be formed not only by hot plate fusion but also by ultrasonic fusion, infrared fusion, or the like. In the case of ultrasonic welding, an ultrasonic horn (horn) is pressed against the outer edge portions of the 1 st seal parts 21, 21A adjacent to each other in the stacking direction D, and ultrasonic waves of about several tens kHz are applied from the ultrasonic horn to the outer edge portions of the 1 st seal parts 21, 21A. By the application of ultrasonic waves, the outer edge portions of the 1 st seal parts 21, 21A are melted and solidified by frictional heat, and the weld layer 30 can be formed. In the hot plate welding, after the heating is stopped, the hot plate and the 1 st sealing portions 21 and 21A need to be kept on standby until they are sufficiently cooled in order to prevent the 1 st sealing portions 21 and 21A from adhering to each other. On the other hand, in ultrasonic welding, natural cooling is performed after the application of ultrasonic waves is stopped, but by releasing heat of the 1 st sealing portions 21, 21A from the ultrasonic welding head or the like, cooling can be performed more quickly than in hot plate welding. Therefore, the time required for the fusion layer forming step can be reduced. Further, burrs adhering to the panel 35 can be reduced as compared with hot plate welding.

In the case of infrared welding, the welding layer 30 can be formed on the 1 st sealing portions 21, 21A by irradiating the laminated 1 st sealing portions 21, 21A with infrared rays from an infrared heater disposed separately from the side surface 11A of the electrode laminate 11. In this method, by controlling the wavelength of infrared rays, only the resins of the 1 st sealing parts 21, 21A can be selectively heated, and the 1 st sealing parts 21 and 21A and the 1 st sealing parts 21, 21A can be welded to each other with good quality in a short time to form the welded layer 30.

In the above embodiment, the thickness of the fusion-spliced layer 30 in the direction from the outer surface of the sealing body 12 to the inner side (the electrode laminated body 11 side) is made different between the non-opening wall and the opening wall, but the extending width of the fusion-spliced layer 30 in the in-plane direction of the side surfaces 12A to 12D when viewed from the lamination direction D may be made different between the non-opening wall and the opening wall. For example, as shown in fig. 12, the weld layers 30 may be provided continuously along the in-plane direction of the side surfaces 12B to 12D on the side surfaces 12B to 12D as the non-opening walls, and the weld layers 30 may be provided partially at a constant interval along the in-plane direction of the side surface a on the side surface 12A as the opening wall. In this case, the width of fusion-bonded layer 30 along the in-plane direction of side surface 12A (the total width of L3a to L3 e) is smaller than the width L1 of fusion-bonded layer 30 along the in-plane direction of side surfaces 12A, 12C and the width L2 of fusion-bonded layer 30 along the in-plane direction of side surface 12B. This embodiment also provides the same effects as those of the above embodiment.

Description of the reference numerals

4 … electric storage module, 11 … electrode laminate, 11a … side face, 12 … seal body, 12a … side face (opening wall), 12B to 12D … side face (non-opening wall), 14 … bipolar electrode, 15 … electrode plate (metal plate), 15a … 1 st face, 15B … 2 nd face, 15c … edge, 21a … 1 st seal part, 22 … nd 2 nd seal part, 30 … fusion layer, 31 … opening region, 32 … non-opening region, D … lamination direction (1 st direction), R … penetration hole, V … internal space, W (W1 to W3) … fusion layer width.