JP7125914B2 - Storage module and method for manufacturing storage module - Google Patents

Description

TECHNICAL FIELD The present invention relates to an electric storage module and a method for manufacturing an electric storage module.

As a conventional power storage module, a bipolar battery is known that includes a bipolar electrode in which a positive electrode is formed on one side of a metal plate and a negative electrode is formed on the other side (see Patent Document 1). A bipolar battery has a laminate formed by laminating a plurality of bipolar electrodes with separators interposed therebetween. A frame-shaped resin portion provided between the bipolar electrodes adjacent to each other in the stacking direction is provided on the side surface of the laminate, and an electrolytic solution is accommodated in the internal space formed between the bipolar electrodes.

JP 2018-133201 A

In the electric storage module as described above, the resin portion joined to the metal plate is formed, for example, by heat-sealing the resin body to the metal plate. In thermal welding, the resin body is heated by, for example, a heater, and cooled while the heated portion and the metal plate are welded. At this time, if the entire resin body is not uniformly heated, residual stress may occur in the resin portion. For example, if a resin body has a melted portion that melts due to heating and a non-melted portion that does not melt, the polymer chains in the unmelted portion are pulled when the melted portion welded to the metal plate shrinks due to cooling. It is stretched and stress is generated. The generated stress remains in the resin portion as residual stress. As the residual stress generated in the resin portion increases, cracks are more likely to occur in the resin portion due to the stress applied to the resin portion, such as the internal pressure of the internal space. If a crack occurs in the resin portion that is joined to the metal plate located in the outermost layer, it may cause leakage of the electrolyte to the outside of the power storage module.

An object of the present invention is to provide an electricity storage module and a method of manufacturing an electricity storage module that can suppress leakage of an electrolytic solution to the outside of the electricity storage module while ensuring the rigidity of the entire electricity storage module.

An electricity storage module according to one aspect of the present invention includes an electrode laminate having a pair of metal end plates and a plurality of bipolar electrodes laminated between the pair of end plates; and an electrolytic solution contained between adjacent bipolar electrodes, and each of the plurality of bipolar electrodes includes a metal plate and a positive electrode provided on one side of the metal plate. , and a negative electrode provided on the other surface of the metal plate, and the sealing body includes a terminal resin portion bonded to a peripheral edge portion of at least one of the pair of end plates, and a peripheral edge portion of the metal plate of the bipolar electrode. and an intermediate resin portion joined to the end resin portion, wherein the crystallinity of the terminal resin portion is lower than the crystallinity of the intermediate resin portion.

In the power storage module according to one aspect of the present invention, the degree of crystallinity of the terminal resin portion is lower than the degree of crystallinity of the intermediate resin portion. The terminating resin portion is joined to the peripheral portion of the end plate. The lower the degree of crystallinity of the resin portion, the lower the rigidity, but the cracks due to the residual stress described above are less likely to occur. In the electric storage module, cracks due to residual stress are less likely to occur in the terminal resin portion than at least in the intermediate resin portion. If the occurrence of cracks in the terminating resin portion is suppressed, leakage of the electrolytic solution to the outside of the power storage module is also suppressed. Further, the rigidity of the entire power storage module can be ensured by the intermediate resin portion having a higher degree of crystallinity than the terminal resin portion. That is, in the power storage module, the electrolyte can be prevented from leaking out of the power storage module while ensuring the rigidity of the power storage module as a whole.

The terminal resin portion and the intermediate resin portion are made of different materials, and the material of the terminal resin portion may be a material that is less likely to crystallize than the material of the intermediate resin portion. In this case, a structure in which the degree of crystallinity of the terminal resin portion is lower than the degree of crystallinity of the intermediate resin portion can be easily realized.

The intermediate resin portion may contain homopolymer polypropylene and the end resin portion may contain random copolymer or block copolymer polypropylene. Random or block copolymer polypropylene is less likely to crystallize than homopolymer polypropylene. Therefore, it is possible to easily realize a configuration in which the degree of crystallinity of the terminal resin portion is lower than that of the intermediate resin portion. As a result, the rigidity of the power storage module as a whole can be ensured in the middle resin portion while the occurrence of cracks in the terminal resin portion is suppressed. In addition, by containing the homopolymer polypropylene in the intermediate resin portion, it is possible to prevent the additive from coming off.

The terminal resin portion and the intermediate resin portion may be made of the same material. Manufacturing costs can be reduced if the terminal resin portion and the intermediate resin portion are manufactured from the same material. Even if the same material is used, the crystallinity relationship between the terminal resin portion and the intermediate resin portion can be satisfied by adjusting the bonding conditions.

One of the pair of end plates is a metal plate of a negative terminal electrode having a metal plate and a negative electrode provided on one side of the metal plate, the electrolytic solution contains an alkaline solution, and the terminal resin part is a negative electrode. It may have a negative electrode-side terminating resin portion joined to the peripheral edge portion of the terminating electrode metal plate. When the electrolyte contains an alkaline solution, the so-called alkali creep phenomenon causes the electrolyte to flow along the surface of the end plate of the negative terminal electrode, pass between the negative terminal resin portion and the end plate, and flow out of the power storage module. There is a risk that it will seep out. If the electrolyte leaks and diffuses to the outside of the power storage module, there is a risk of corrosion of a metal plate arranged in contact with the power storage module, short-circuiting between the power storage module and the restraining member, and the like. In addition to the internal pressure of the internal space, stress due to the alkali creep phenomenon is applied to the negative electrode-side terminal resin portion. In this regard, since the crystallinity of the terminal resin portion is lower than that of the intermediate resin portion, cracks due to residual stress are less likely to occur in the negative electrode-side terminal resin portion than at least in the intermediate resin portion. Therefore, even if stress due to the alkali creep phenomenon is applied to the negative electrode-side terminating resin portion in addition to the internal pressure of the internal space, leakage of the electrolytic solution to the outside of the electric storage module is suppressed.

The electrolyte contains an alkaline solution, and one of the pair of end plates is arranged outside the metal plate and the negative terminal electrode having the negative electrode provided on one side of the metal plate in the stacking direction of the electrode laminate. The terminating resin portion may include a negative terminating resin portion joined to a peripheral edge portion of the negative electrode side outermost metal plate. In this case as well, even if stress due to the alkali creep phenomenon is applied to the negative electrode-side terminating resin portion in addition to the internal pressure of the internal space, leakage of the electrolytic solution to the outside of the power storage module is suppressed.

The other of the pair of end plates is a metal plate of a positive electrode termination electrode having a metal plate and a positive electrode provided on one side of the metal plate, and the termination resin portion is joined to the peripheral edge portion of the metal plate of the positive electrode termination electrode. The positive electrode side termination resin portion may be included, and the crystallinity of the positive electrode side termination resin portion may be higher than the crystallinity of the negative electrode side termination resin portion. The occurrence of cracks in the positive electrode-side terminal resin portion has little relationship with leakage of the electrolytic solution due to the alkaline creep phenomenon. If the crystallinity of the positive electrode side terminating resin portion is higher than the crystallinity of the negative electrode side terminating resin portion, the positive electrode side terminating resin portion has at least higher rigidity than the negative electrode side terminating resin portion. Therefore, in this electricity storage module, the rigidity of the entire electricity storage module can be further improved while preventing the electrolyte from leaking out of the electricity storage module due to the alkali creep phenomenon.

The other of the pair of end plates is a positive electrode-side outermost metal plate disposed outside the positive terminal electrode having a positive electrode provided on one side of the metal plate and the positive electrode provided on one side of the metal plate in the stacking direction of the electrode laminate, The termination resin portion has a positive electrode side termination resin portion joined to the peripheral edge portion of the positive electrode side outermost metal plate, and the crystallinity of the positive electrode side termination resin portion is higher than the crystallinity of the negative electrode side termination resin portion. It may be. In this electricity storage module, the rigidity of the entire electricity storage module can be further improved while preventing the electrolyte from leaking out of the electricity storage module due to the alkaline creep phenomenon.

The terminal resin portion may have a facing surface facing the intermediate resin portion. The facing surface may include areas that are bonded and areas that are not bonded to the end plate. In this case, when the resin body is cooled, the area that is not bonded to the end plate shrinks more than the area that is bonded to the end plate, and there is a problem that residual stress is likely to occur in the resin section. In the electricity storage module, at least one of the pair of terminal resin portions has a relatively low degree of crystallinity. Generation of residual stress in at least one of the above is suppressed. Therefore, cracks due to residual stress are less likely to occur.

The end plate may be roughened in the joint region between the terminating resin portion and the end plate. In this case, it is possible to improve the joint strength between the terminating resin portion and the end plate due to the anchor effect. Therefore, it is possible to further suppress peeling of the terminal resin portion, and to further suppress leakage of the electrolytic solution.

According to another aspect of the present invention, there is provided a method of manufacturing an electricity storage module in which a plurality of bipolar electrodes including a metal plate, a positive electrode provided on one side of the metal plate, and a negative electrode provided on the other side of the metal plate are made of metal. A method for manufacturing an electric storage module having an electrode laminate laminated between a pair of end plates made by the company, comprising: an outermost layer forming step of joining a terminating resin portion to at least one peripheral edge portion of the pair of end plates; and an intermediate layer forming step of joining the intermediate resin portion to the peripheral edge portion of the metal plate of the electrode, so that the degree of crystallinity after joining the terminal resin portion is lower than the degree of crystallinity after joining the intermediate resin portion. , the outermost layer forming step and the intermediate layer forming step are carried out.

In the power storage module manufactured by the manufacturing method described above, the crystallinity of the terminal resin portion is lower than that of the intermediate resin portion. The terminating resin portion is bonded to the peripheral portion of the end plate. In the electric storage module, cracks due to residual stress are less likely to occur in the terminal resin portion than at least in the intermediate resin portion. If the occurrence of cracks in the terminating resin portion is suppressed, leakage of the electrolytic solution to the outside of the power storage module is also suppressed. Moreover, the rigidity of the entire power storage module can be ensured by the intermediate resin portion. That is, in the power storage module, the electrolyte can be prevented from leaking out of the power storage module while ensuring the rigidity of the power storage module as a whole.

Different materials may be used for the terminating resin portion and the intermediate resin portion, and a material that is less likely to crystallize than the material for the intermediate resin portion may be used as the material for the terminating resin portion. In this case, a structure in which the crystallinity of the terminal resin portion is lower than that of the intermediate resin portion can be easily realized.

A homopolymer polypropylene may be used as the intermediate resin portion, and a random copolymer or block copolymer polypropylene may be used as the terminal resin portion. Random or block copolymer polypropylene is less likely to crystallize than homopolymer polypropylene. Therefore, it is possible to easily realize a structure in which the degree of crystallinity of the terminal resin portion is lower than that of the intermediate resin portion. As a result, the rigidity of the entire power storage module can be ensured in the intermediate resin portion while suppressing the occurrence of cracks in the terminal resin portion. In addition, by containing the homopolymer polypropylene in the intermediate resin portion, it is possible to prevent the additive from coming off.

The same material may be used for the terminating resin portion and the intermediate resin portion, and the cooling rate during bonding of the terminating resin portion may be faster than the cooling rate during bonding of the intermediate resin portion. In this case, the crystallinity of the terminal resin portion after cooling may be lower than the crystallinity of the intermediate resin portion after cooling. Therefore, in the electricity storage module manufactured by this manufacturing method, the leakage of the electrolytic solution to the outside of the electricity storage module can be suppressed while ensuring the rigidity of the entire electricity storage module.

One of the pair of end plates is a negative terminal electrode having a metal plate and a negative electrode provided on one side of the metal plate. The outermost layer forming step and the intermediate layer forming step are performed so that the crystallinity of the negative electrode-side terminal resin portion after bonding is lower than the crystallinity of the intermediate resin portion after bonding. You may In this case, cracks due to residual stress are less likely to occur in the negative electrode-side terminal resin portion than in at least the intermediate resin portion. Therefore, even if stress due to the alkali creep phenomenon is applied to the negative electrode-side terminating resin portion in addition to the internal pressure of the internal space, leakage of the electrolytic solution to the outside of the electric storage module is suppressed.

one of the pair of end plates is a negative electrode-side outermost metal plate disposed outside the negative terminal electrode having a negative electrode provided on one side of the metal plate and the negative electrode provided on one side of the metal plate in the stacking direction of the electrode laminate; In the outermost layer forming step, in the stacking direction, a negative electrode-side terminating resin portion as a terminating resin portion is joined to the peripheral edge portion of the negative electrode-side outermost metal plate, and the degree of crystallinity after bonding of the negative electrode-side terminating resin portion is the intermediate resin portion. The outermost layer forming step and the intermediate layer forming step may be carried out so that the degree of crystallinity after bonding is lower than that of . Also in this case, even if stress due to the alkali creep phenomenon is applied to the terminal resin portion in addition to the internal pressure of the internal space, leakage of the electrolytic solution to the outside of the electric storage module is suppressed.

The other of the pair of end plates is a metal plate of a positive electrode termination electrode having a metal plate and a positive electrode provided on one side of the metal plate. The outermost layer forming step is performed so that the positive electrode side termination resin portion as the resin portion is joined, and the crystallinity after bonding of the positive electrode side termination resin portion is higher than the crystallinity after bonding of the negative electrode side termination resin portion. may be implemented. In this case, in the electricity storage module manufactured by this manufacturing method, the rigidity of the entire electricity storage module can be further improved while preventing the electrolyte from leaking out of the electricity storage module due to the alkali creep phenomenon.

ADVANTAGE OF THE INVENTION According to one aspect of the present invention, it is possible to provide an electricity storage module and a method for manufacturing the electricity storage module that can suppress leakage of an electrolytic solution to the outside of the electricity storage module while ensuring the rigidity of the entire electricity storage module.

1 is a schematic cross-sectional view showing a power storage device including power storage modules according to a first embodiment; FIG. 1 is a schematic cross-sectional view showing a power storage module according to a first embodiment; FIG. 4 is a flow chart for explaining a manufacturing process of an electric storage module; It is a figure which shows an example of the process in which a resin body is heated. FIG. 10 is a diagram showing an example of a process of cooling a resin body in a power storage module according to a comparative example; FIG. 10 is a diagram showing an example of a process of cooling a resin body in an electricity storage module; FIG. 11 is a schematic cross-sectional view showing a power storage module according to a second embodiment;

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the description of the drawings, the same reference numerals are used for the same or equivalent elements, and overlapping descriptions are omitted.
[First embodiment]

A first embodiment of a power storage device will be described with reference to FIG. FIG. 1 is a schematic cross-sectional view showing a first embodiment of a power storage device. A power storage device 1 shown in FIG. 1 is used as a battery for various vehicles such as forklifts, hybrid vehicles, and electric vehicles. The power storage device 1 includes a plurality of (three in the configuration shown in FIG. 1 ) power storage modules 4 , but may include a single power storage module 4 . The power storage module 4 is a bipolar battery. The storage module 4 is, for example, a secondary battery such as a nickel-hydrogen secondary battery or a lithium-ion secondary battery, but may be an electric double layer capacitor. In the following description, a nickel-metal hydride secondary battery is exemplified.

A plurality of power storage modules 4 can be stacked via a conductive structure 5 such as a metal plate, for example. When viewed from the stacking direction D, the power storage module 4 and the conductive structure 5 have, for example, a rectangular shape. Details of each power storage module 4 will be described later. In the configuration shown in FIG. 1 , the conductive structures 5 are also arranged outside the storage modules 4 positioned at both ends in the stacking direction D of the storage modules 4 . Note that the power storage device 1 may have a structure in which the conductive structures 5 are not arranged outside the power storage modules 4 located at both ends in the stacking direction D. A power storage module 4 may be arranged. That is, the storage module 4 may be the outermost layer (stack outermost layer) of the laminate of the storage module 4 and the conductive structure 5 in the storage device 1 . In this case, a positive electrode terminal 6 and a negative electrode terminal 7, which will be described later, are provided for the power storage module 4 in the outermost layer of the stack. The conductive structure 5 is electrically connected to adjacent power storage modules 4 . Thereby, the plurality of power storage modules 4 are connected in series in the stacking direction D. As shown in FIG.

In the configuration shown in FIG. 1, in the stacking direction D, the conductive structure 5 positioned at one end is connected to the positive electrode terminal 6, and the conductive structure 5 positioned at the other end is connected to the negative electrode terminal 7. It is The positive terminal 6 may be integral with the conductive structure 5 connected with the positive terminal 6 . The negative terminal 7 may be integral with the conductive structure 5 that is connected to the negative terminal 7 . The positive terminal 6 and the negative terminal 7 extend in a direction intersecting the stacking direction D. As shown in FIG. Charging and discharging of the power storage device 1 are performed by the positive electrode terminal 6 and the negative electrode terminal 7 .

The conductive structure 5 can also function as a heat sink for releasing heat generated in the power storage module 4 . Coolants such as air and gas pass through the plurality of gaps 5 a provided inside the conductive structure 5 , so that heat from the power storage module 4 can be efficiently released to the outside. Each gap 5a extends, for example, in a direction intersecting the stacking direction D and the direction in which the positive electrode terminal 6 and the negative electrode terminal 7 are pulled out. The conductive structure 5 functions not only as a connecting member that electrically connects the storage modules 4, but also as a radiator plate that dissipates the heat generated in the storage modules 4 by circulating a coolant in the gaps 5a. have a combination of functions. The conductive structure 5 is smaller than the power storage module 4 when viewed from the stacking direction D, but may be the same size as the power storage module 4 or larger than the power storage module 4 .

The power storage device 1 may include a restraining member 3 that restrains the alternately stacked power storage modules 4 and the conductive structures 5 in the stacking direction D. As shown in FIG. The restraining member 3 includes a pair of restraining plates 8A, 8B, bolts 9 and nuts 10. As shown in FIG. Bolts 9 and nuts 10 are fastened to the restraining plates 8A and 8B to connect the restraining plates 8A and 8B. An insulating film F such as, for example, a resin film is arranged between each constraining plate 8A, 8B and the conductive structure 5 . When the stack outermost layer is the power storage module 4 , an insulating film F is arranged between the restraining member 3 and the power storage module 4 .

Each restraining plate 8A, 8B is made of metal, for example. Seen from the stacking direction D, each of the constraining plates 8A, 8B and the insulating film F has, for example, a rectangular shape. The insulating film F is larger than the conductive structure 5 and each constraining plate 8 A, 8 B is larger than the storage module 4 . Each of the restraint plates 8A and 8B is formed by, for example, aluminum die-casting to secure strength and design flexibility and reduce weight.

When viewed from the stacking direction D, an insertion hole H1 through which the shaft of the bolt 9 is inserted is provided outside the power storage module 4 at the edge of the restraining plate 8A. Similarly, when viewed from the stacking direction D, an insertion hole H2 through which the shaft of the bolt 9 is inserted is provided outside the power storage module 4 at the edge of the restraining plate 8B. When each constraining plate 8A, 8B has a rectangular shape as viewed from the stacking direction D, the insertion holes H1 and H2 are positioned at the corners of the constraining plates 8A, 8B.

The constraining plate 8A is abutted against the conductive structure 5 connected to the negative electrode terminal 7 via the insulating film F, and the constraining plate 8B is placed against the conductive structure 5 connected to the positive electrode terminal 6 or the storage module 4 with the insulating film. It is pushed through F. The bolt 9 is passed through the insertion hole H1 and the insertion hole H2 from the restraining plate 8A toward the restraining plate 8B, for example. A nut 10 is screwed onto the tip of the bolt 9 protruding from the restraining plate 8B. As a result, the insulating film F, the conductive structure 5 and the power storage module 4 are sandwiched and unitized, and a restraining load is applied in the stacking direction D. As shown in FIG.

Next, the configuration of the power storage module 4 according to the first embodiment will be described in detail with reference to FIG. 2 . 2 is a schematic cross-sectional view showing the internal configuration of the power storage module shown in FIG. 1. FIG. As shown in FIG. 2 , the power storage module 4 includes an electrode laminate 11 and a resin sealing body 12 that seals the electrode laminate 11 . Electrode laminate 11 includes a plurality of metal plates 15 and a plurality of electrodes stacked along stacking direction D of power storage module 4 with separators 13 interposed therebetween. These electrodes include a stack of multiple bipolar electrodes 14 , a negative terminal electrode 18 and a positive terminal electrode 19 . The plurality of metal plates 15 includes a pair of metal end plates arranged at both ends in the stacking direction D among the plurality of metal plates 15 . That is, in the present embodiment, the end plate is the outermost metal plate located on the outermost side in the electrode laminate 11 included in one power storage module 4 . All the bipolar electrodes 14 in one electrode laminate 11 are laminated between a pair of end plates. The pair of end plates includes a negative electrode-side outermost metal plate located on the side of the negative terminal electrode 18 described later, and a positive electrode-side outermost metal plate located on the side of the positive terminal electrode 19 described later.

The bipolar electrode 14 has a metal plate 15 including one surface 15a and the other surface 15b opposite to the one surface 15a, a positive electrode 16 provided on the one surface 15a, and a negative electrode 17 provided on the other surface 15b. ing. The positive electrode 16 is a positive electrode active material layer formed by coating the metal plate 15 with a positive electrode active material. The negative electrode 17 is a negative electrode active material layer formed by coating the metal plate 15 with a negative electrode active material. 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 one side in the stacking direction D with the separator 13 interposed therebetween. 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 in the stacking direction D with the separator 13 interposed therebetween.

The negative terminal electrode 18 has a metal plate 15 and a negative electrode 17 provided on the other surface 15 b of the metal plate 15 . In the first embodiment, the metal plate 15 of the negative terminal electrode 18 is the outermost negative metal plate forming one of the pair of end plates. The negative terminal electrode 18 is arranged at one end in the stacking direction D so that the other surface 15b faces the central side in the stacking direction D of the electrode stack 11 . One surface 15a of the metal plate 15 of the negative terminal electrode 18 constitutes one outer surface in the stacking direction D of the electrode laminate 11, and is electrically connected to one conductive structure 5 (see FIG. 1) adjacent to the electricity storage module 4. properly connected. The negative electrode 17 provided on the other surface 15b of the metal plate 15 of the negative terminal electrode 18 faces the positive electrode 16 of the bipolar electrode 14 at one end in the stacking direction D with the separator 13 interposed therebetween.

The positive terminal electrode 19 has a metal plate 15 and a positive electrode 16 provided on one surface 15 a of the metal plate 15 . In the first embodiment, the metal plate 15 of the positive terminal electrode 19 is the positive electrode side outermost metal plate, the other of the pair of end plates. The positive terminal electrode 19 is arranged at the other end in the stacking direction D so that one surface 15 a faces the central side in the stacking direction D of the electrode stack 11 . The positive electrode 16 provided on one surface 15a 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 with the separator 13 interposed therebetween. The other surface 15b of the metal plate 15 of the positive terminal electrode 19 constitutes the other outer surface in the stacking direction D of the electrode laminate 11, and is electrically connected to the other conductive structure 5 (see FIG. 1) adjacent to the electricity storage module 4. properly connected.

The metal plate 15 is made of metal such as nickel or nickel-plated steel plate, for example. As an example, the metal plate 15 is a rectangular metal foil made of nickel. A peripheral portion 15c of the metal plate 15 has a rectangular frame shape and is an uncoated region where the positive electrode active material and the negative electrode active material are not coated. Examples of the positive electrode active material forming the positive electrode 16 include nickel hydroxide. Examples of negative electrode active materials that constitute the negative electrode 17 include hydrogen storage alloys. In the first embodiment, the formation area of the negative electrode 17 on the other surface 15 b of the metal plate 15 is one size larger than the formation area of the positive electrode 16 on the one surface 15 a of the metal plate 15 .

The separator 13 is formed in a sheet shape, for example. Examples of the separator 13 include porous films made of polyolefin resins such as polyethylene (PE) and polypropylene (PP), and woven or nonwoven fabrics made of polypropylene, methyl cellulose, and the like. The separator 13 may be reinforced with a vinylidene fluoride resin compound. Note that the separator 13 is not limited to a sheet shape, and may be bag-shaped.

The sealing body 12 is made of, for example, an insulating resin, and is formed into a rectangular tubular shape as a whole. The sealing body 12 is provided so as to surround the side surface 11 a of the electrode laminate 11 . The encapsulant 12 holds the peripheral portion 15c on the side surface 11a. The sealing body 12 is, for example, an insulating resin having alkali resistance. The sealing body 12 has a resin portion 21 , a resin portion 22 , a resin portion 23 and a housing portion 24 . The resin portion 21, the resin portion 22, and the resin portion 23 are provided continuously over the entire periphery of the peripheral edge portion 15c of the metal plate 15, and have a rectangular frame shape when viewed from the stacking direction D. As shown in FIG. The housing portion 24 surrounds the resin portion 21, the resin portion 22, and the resin portion 23 from the outside along the side surface 11a. The housing portion 24 is coupled to each of the resin portion 21 , the resin portion 22 , and the resin portion 23 .

The power storage module 4 includes a bipolar electrode unit 31 including a plurality of bipolar electrodes 14 and a resin portion 21 , a negative electrode unit 32 including a negative electrode 18 and a resin portion 22 , a positive electrode 19 and a resin portion 23 . and a positive terminal electrode unit 33 including The negative terminal electrode unit 32 is joined to one end of the bipolar electrode unit 31 . The positive terminal electrode unit 33 is joined to the other end of the bipolar electrode unit 31 . The resin portion 21 is joined to the peripheral portion 15 c of the metal plate 15 of the plurality of bipolar electrodes 14 . The resin portion 22 is joined to the peripheral portion 15 c of the metal plate 15 of the negative terminal electrode 18 . The resin portion 23 is joined to the peripheral portion 15 c of the metal plate 15 of the positive terminal electrode 19 .

In the first embodiment, for example, the resin portion 22 is the negative terminal resin portion, the resin portion 23 is the positive electrode terminal resin portion, and the resin portion 21 is the intermediate resin portion. For example, the negative terminal resin portion is bonded to one peripheral edge portion 15c of the end plate, the positive electrode terminal resin portion is bonded to the other peripheral edge portion 15c of the end plate, and the intermediate resin portion is the peripheral edge of the metal plate of the bipolar electrode 14. It is joined to the portion 15c.

The resin portion 21, the resin portion 22, and the resin portion 23 each have a facing surface 25 that faces the resin portion 21, the resin portion 22, and the resin portion 23 that are adjacent to each other. The resin portion 21 is joined to the one surface 15a and the other surface 15b of the metal plate 15 on the surface 25 facing the resin portion 21, the resin portion 22, or the resin portion 23 adjacent thereto. The resin portion 22 is joined to the other surface 15 b of the metal plate 15 of the negative terminal electrode 18 on the surface 25 facing the adjacent resin portion 21 . The resin portion 23 is joined to one surface 15 a of the metal plate 15 of the positive terminal electrode 19 on the surface 25 facing the adjacent resin portion 21 . Each of the resin portion 21, the resin portion 22, and the resin portion 23 includes a region K1 bonded to the metal plate 15 and a region K2 not bonded to the metal plate 15 on the facing surface 25 bonded to the metal plate 15. .

The surface of each metal plate 15 is roughened in a bonding region K3 where the resin portion 21, the resin portion 22, and the resin portion 23 are bonded. The roughened region may be only the joint region K3, but in the first embodiment, the entire surface of the metal plate 15 is roughened. Roughening can be achieved by forming a plurality of projections by, for example, electroplating. By forming the plurality of projections, the molten resin enters between the plurality of projections formed by surface roughening at the joint interface between the metal plate 15 and the resin portions 21, 22, and 23. , the anchor effect is exhibited. Thereby, the bonding strength between the metal plate 15 and the resin portions 21, 22, and 23 can be improved. The projections formed during surface roughening have, for example, a shape that tapers from the proximal side to the distal side. As a result, the cross-sectional shape between adjacent projections becomes an undercut shape, making it possible to enhance the anchor effect.

The resin portion 21, the resin portion 22, and the resin portion 23 are welded to the metal plate 15 by heat and are airtightly joined. The resin portion 21, the resin portion 22, and the resin portion 23 are films having a predetermined thickness in the stacking direction D, for example. The inside of each of the resin portion 21 , the resin portion 22 , and the resin portion 23 is positioned so as to overlap the peripheral edge portion 15 c of the metal plate 15 when viewed from the stacking direction D. As shown in FIG. The outer sides of the resin portion 21 , the resin portion 22 , and the resin portion 23 protrude beyond the edge of the metal plate 15 , and the tip portions thereof are supported by the housing portion 24 . The resin portion 21, the resin portion 22, and the resin portion 23 that are adjacent to each other along the stacking direction D may be separated from each other or may be in contact with each other. Further, the outer edge portions of the resin portion 21, the resin portion 22, and the resin portion 23 may be joined together by, for example, hot plate welding.

The housing portion 24 is provided outside the electrode laminate 11 , the resin portion 21 , the resin portion 22 , and the resin portion 23 and constitutes the outer wall of the power storage module 4 . The housing part 24 is formed, for example, by injection molding of resin, and extends along the stacking direction D over the entire length of the electrode stack 11 . The housing part 24 has a rectangular frame shape extending with the stacking direction D as an axial direction. The housing portion 24 is welded to the outer surface of the resin portion 21 by heat during injection molding, for example.

The resin portion 21, the resin portion 22, the resin portion 23, and the housing portion 24 form an internal space V between adjacent electrodes and seal the internal space V. As shown in FIG. More specifically, the housing part 24, together with the resin part 21, the resin part 22, and the resin part 23, is adjacent to each other along the stacking direction D between the bipolar electrodes 14 that are adjacent to each other along the stacking direction D. It seals between the negative terminal electrode 18 and the bipolar electrode 14 and between the positive terminal electrode 19 and the bipolar electrode 14 that are adjacent to each other along the stacking direction D, respectively. As a result, airtight 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. ing. This internal space V accommodates an electrolytic solution (not shown) containing an alkaline solution such as an aqueous potassium hydroxide solution. The electrolytic solution is impregnated in the separator 13 , the positive electrode 16 and the negative electrode 17 .

The resin portion 21, the resin portion 22, the resin portion 23, and the housing portion 24 are, for example, an insulating resin having alkali resistance. In the first embodiment, main constituent materials of the resin portion 21, the resin portion 22, the resin portion 23, and the housing portion 24 include, for example, polypropylene (PP), polyphenylene sulfide (PPS), modified polyphenylene ether (modified PPE ) and the like. Polypropylene includes, for example, homopolymers of homopolymerization, and random and block copolymers of copolymerization. An additive having an antioxidant function may be added to the resin portion 21, the resin portion 22, the resin portion 23, and the housing portion 24, for example. Additives having an antioxidant function include, for example, hindered phenols.

In the first embodiment, the crystallinity of the resin portion 22 is lower than the crystallinity of the resin portions 21 and 23 . In other words, the degree of crystallinity of the resin portion 21 and the degree of crystallinity of the resin portion 23 is higher than the degree of crystallinity of the resin portion 22 . The difference in the degree of crystallinity of the resin portion is brought about by the difference in materials and the difference in bonding conditions, such as the difference in cooling rate. In the first embodiment, the difference in crystallinity between the resin portions 21 , 22 and 23 is caused by the difference in the materials of the resin portions 21 , 22 and 23 .

In the first embodiment, the degree of crystallinity of the resin portion 23 is equal to the degree of crystallinity of the resin portion 21, but it is not limited to this. The degree of crystallinity of at least one of the resin portions 22 and 23 may be lower than the degree of crystallinity of the resin portion 21 . For example, as a modification of the first embodiment, the crystallinity of the resin portion 23 may be lower than the crystallinity of the resin portion 21 . In this modification, the degree of crystallinity of resin portion 23 may be equal to the degree of crystallinity of resin portion 22 .

In the first embodiment, the resin portion 22 and the resin portions 21 and 23 are made of different materials. The material of the resin portion 22 is a material that is less likely to crystallize than the materials of the resin portions 21 and 23 . The resin portion 21 and the resin portion 23 contain homopolymer polypropylene as a main constituent material. The resin part 22 contains random copolymer or block copolymer polypropylene as a main constituent material. The melting point of block copolymer polypropylene is higher than that of random copolymer polypropylene. Therefore, when the main constituent material of the resin portion 22 is a block copolymer polypropylene, the encapsulant 12 can be formed more easily and reliably than when it is a random copolymer polypropylene. As a result, product reliability is improved.

In the first embodiment, the resin portion 21 and the resin portion 23 are made of the same material, but are not limited to this. At least one of the resin portion 22 and the resin portion 23 and the resin portion 21 may be made of different materials. The material of the resin portion 21 may be a material that is less likely to crystallize than the material of at least one of the resin portions 22 and 23 . For example, in the modified example described above, the resin portion 23 and the resin portion 21 may be made of different materials, and the material of the resin portion 23 may be a material that is less likely to crystallize than the material of the resin portion 21 .

In the first embodiment, the resin portion 21 and the resin portion 23 contain homopolymer polypropylene as a main material, and the resin portion 22 contains a random copolymer or block copolymer polypropylene as a main constituent material, but they are limited to this. not. At least one of the resin portion 22 and the resin portion 23 may contain random copolymer or block copolymer polypropylene. For example, in the variations described above, resin portion 21 may contain homopolymer polypropylene, and resin portions 22 and 23 may contain random copolymer or block copolymer polypropylene.

Next, an example of a method for manufacturing the power storage module 4 will be described with reference to FIGS. 3 and 4. FIG. FIG. 3 is a flow chart showing an embodiment of the method for manufacturing the electric storage module described above. FIG. 4 is a diagram showing an example of a process in which the resin body is heated. As shown in FIG. 3, the method for manufacturing the power storage module 4 includes a formation step S1, a lamination step S2, a sealing step S3, and an injection step S4.

First, in the forming step S1, the bipolar electrode unit 31, the negative terminal electrode unit 32, and the positive terminal electrode unit 33 are formed. The forming step S1 includes a first forming step of forming the negative terminal electrode unit 32, a second forming step of forming the bipolar electrode unit 31, and a third forming step of forming the positive terminal electrode unit 33. . The first formation process, the second formation process, and the third formation process may be performed in any order, or may be performed in parallel. The first forming step and the third forming step are included in the outermost layer forming step of joining the terminating resin portion to the peripheral portion of the end plate. The second forming step is included in the intermediate layer forming step of bonding the intermediate resin portion to the peripheral portion of the metal plate of the bipolar electrode 14 .

In the first formation step, the negative termination electrode 18 is prepared. Subsequently, a resin body to be the resin portion 22 is joined to the peripheral portion 15c of the other surface 15b of the metal plate 15 of the negative terminal electrode 18 by thermal welding. Thus, the negative terminal electrode unit 32 is formed.

In the second forming process, a predetermined number of bipolar electrodes 14 are prepared. Subsequently, a plurality of bipolar electrodes 14 are stacked with separators 13 interposed therebetween. Subsequently, a resin body to be the resin portion 21 is joined to the peripheral edge portion 15c of the one surface 15a and the peripheral edge portion 15c of the other surface 15b of the metal plate 15 of each bipolar electrode 14 by thermal welding. Thereby, the bipolar electrode unit 31 is formed.

In the third formation step, the positive termination electrode 19 is prepared. Subsequently, a resin body to be the resin portion 23 is joined to the peripheral edge portion 15c of the one surface 15a of the metal plate 15 of the positive terminal electrode 19 by thermal welding. Thus, the positive terminal electrode unit 33 is formed.

In the first embodiment, in the first forming step, the second forming step, and the third forming step, the metal plate 15 is formed of the resin body as the resin portion 21, the resin portion 22, and the resin portion 23 by the same method. is spliced to FIG. 4 shows, as an example, the process of welding the resin body 40 to the metal plate 15 of the bipolar electrode 14 in the first forming process. For example, as shown in FIG. 4, the resin body 40 is heated by the heater 41 . At this time, at least the heating surface 42 facing the heater 41 is heated to exceed the melting point of the material of the resin body 40 . Subsequently, the rubber member 43 presses the resin body against the metal plate 15 to weld the heating surface 42 of the resin body 40 to the metal plate 15 . In the first embodiment, part of the heating surface 42 is welded to the metal plate 15 . Subsequently, the resin body 40 is cooled while the heating surface 42 is welded to the metal plate 15 .

As a result, the resin portion 22 joined to the peripheral edge portion 15c of the metal plate 15 of the negative electrode terminal electrode 18 is formed in the first forming step, and the peripheral edge portion 15c of the metal plate 15 of the positive electrode terminal electrode 19 is formed in the third forming step. A resin portion 23 is formed which is joined to the , and a resin portion 21 which is joined to the peripheral edge portion 15c of the metal plate 15 of the bipolar electrode 14 is formed in the third forming step. The heated surface 42 after cooling corresponds to the facing surface 25 joined to the metal plate 15 .

The first formation process, the second formation process, and the third formation process are performed so that the degree of crystallinity after bonding of the resin portion 22 is lower than the degree of crystallinity after bonding of the resin portions 21 and 23 . will be implemented. In other words, in the first forming step, the second forming step, and the third forming step, the degree of crystallinity after the crystallization of the resin portions 21 and 23 is the same as the degree of crystallization after the crystallization of the resin portion 22. It is carried out to be higher than

In the first embodiment, the second forming step and the third forming step are performed so that the degree of crystallinity after bonding of the resin portion 23 is equal to the degree of crystallinity after bonding of the resin portion 21. It is not limited to this. The first to third forming steps may be performed so that the degree of crystallinity after bonding of at least one of the resin portion 22 and the resin portion 23 is lower than the degree of crystallinity after bonding of the resin portion 21. . For example, in the modified example described above, the second forming step and the third forming step are performed so that the degree of crystallinity after bonding of the resin portion 23 is lower than the degree of crystallinity after bonding of the resin portion 21. may In this modification, the first forming step and the third forming step may be performed so that the degree of crystallinity after bonding of the resin portion 23 is equal to the degree of crystallinity after bonding of the resin portion 22 .

In the first embodiment, the difference in crystallinity between the resin portions 21 , 22 and 23 is caused by the difference in the materials of the resin portions 21 , 22 and 23 . In the first embodiment, different materials are used for the resin portions 21 and 23 and the resin portion 22 . A material that is less likely to crystallize than the material of the resin portions 21 and 23 is used as the material of the resin portion 22 .

In the first embodiment, homopolymer polypropylene is used as the main constituent material of the resin portion 21 and the resin portion 23 . Random copolymer or block copolymer polypropylene is used as the main constituent material of the resin portion 22 . The melting point of block copolymer polypropylene is higher than that of random copolymer polypropylene. Therefore, when the main constituent material of the resin portion 22 is a block copolymer polypropylene, the encapsulant 12 can be formed more easily and reliably than when it is a random copolymer polypropylene.

Although the same material is used for the resin portion 21 and the resin portion 23 in the first embodiment, the material is not limited to this. At least one of the resin portion 22 and the resin portion 23 and the resin portion 21 may be made of different materials. A material that is less likely to crystallize than the material of at least one of the resin portions 22 and 23 may be used as the material of the resin portion 21 . For example, in the modified example described above, different materials may be used for the resin portion 23 and the resin portion 21, and a material that is less likely to crystallize than the material for the resin portion 23 may be used for the resin portion 21. .

In the first embodiment, homopolymer polypropylene is used as the main constituent material of the resin portion 21 and the resin portion 23, and random copolymer or block copolymer polypropylene is used as the main constituent material of the resin portion 22. but not limited to this. Random copolymer or block copolymer polypropylene may be used as a main constituent material of at least one of the resin portion 22 and the resin portion 23 . For example, in the modified example described above, homopolymer polypropylene may be used as the constituent material of the resin portion 21, and random copolymer or block copolymer polypropylene may be used as the constituent material of the resin portion 22 and the resin portion 23. may be

Next, in the stacking step S2, the negative terminal electrode unit 32 is joined to one end of the bipolar electrode unit 31, and the positive terminal electrode unit 33 is joined to the other end of the bipolar electrode unit 31. As shown in FIG. Thus, the electrode laminate 11 is formed. At this time, the negative terminal electrode unit 32 is laminated on the bipolar electrode 14 on one end side of the bipolar electrode unit 31 with the separator 13 interposed therebetween. The bipolar electrode unit 31 is laminated on the positive terminal electrode 19 of the positive terminal electrode unit 33 with the separator 13 interposed therebetween.

Next, in the sealing step S3, after placing the electrode laminate 11 in a mold (not shown) for injection molding, the housing part 24 is molded by injecting molten resin into the mold. That is, the sealing body 12 is formed so as to surround the side surface 11 a of the electrode laminate 11 to seal the electrode laminate 11 . Next, in the injection step S4, an electrolytic solution is injected into the internal space V between the electrodes. The power storage module 4 is obtained through the above steps.

Next, functions and effects of the power storage module 4 will be described with reference to FIGS. 5 and 6. FIG. FIG. 5 is a diagram showing an example of a process of cooling a resin body in a power storage module according to a comparative example. FIG. 6 is a diagram showing an example of a process of cooling a resin body in the power storage module according to the first embodiment.

As described above, the resin body 40 is heated by, for example, a heater, and cooled while the heated heating surface 42 is welded to the metal plate 15 . At this time, it is difficult to uniformly heat the entire resin body 40 , and a melted portion 46 and a non-melted portion 47 exist in the resin body 40 . In FIGS. 5 and 6, the fusion zone 46 is indicated by dot hatching.

The melted portion 46 welded to the metal plate 15 shrinks by cooling, but the unmelted portion 47 shrinks less than the melted portion 46 even when cooled. Therefore, when the melted portion 46 welded to the metal plate 15 shrinks, the polymer chains of the unmelted portion 47 are stretched and stress is generated. As a result, residual stress may occur inside the resin portion 21 , the resin portion 22 , and the resin portion 23 . As the residual stress generated in the resin portion increases, cracks are more likely to occur in the resin portion due to the stress applied to the resin portion due to the internal pressure of the internal space V or the alkali creep phenomenon. If a crack occurs in the resin portion 22 joined to the metal plate 15 of the negative terminal electrode 18, it may cause leakage of the electrolytic solution to the outside of the power storage module.

In FIGS. 5 and 6, arrows A1 and A2 represent images of contraction of the melted portion 46, and arrows B1 and B2 represent images of the stress generated by stretching the polymer chains of the unmelted portion 47. . The lengths of arrows A1 and A2 represent the degree of contraction, and the lengths of arrows B1 and B2 represent the strength of stress. FIG. 6 shows a case where the resin portion is formed so that the degree of crystallinity is lower than that in FIG. The difference in the degree of crystallinity of the resin portion is caused by the difference in cooling rate, the difference in materials, and the like. As indicated by arrows B1 and B2 in FIGS. 5 and 6, the lower the degree of crystallinity of the resin portion, the more the stress generated by stretching the polymer chains of the non-melting portion 47 during the formation of the resin portion. weakens. Therefore, the lower the degree of crystallinity of the resin portion, the more difficult it is for cracks to occur due to residual stress.

In power storage module 4 , the crystallinity of at least one of resin portion 22 and resin portion 23 is lower than the crystallinity of resin portion 21 . Therefore, in the electric storage module 4 , at least one of the resin portion 22 and the resin portion 23 is less likely to crack due to residual stress than at least the resin portion 21 . If the occurrence of cracks in at least one of the resin portions 22 and 23 is suppressed, leakage of the electrolytic solution to the outside of the power storage module 4 is also suppressed. Moreover, the rigidity of the entire power storage module 4 can be ensured by the resin portion 21 . That is, in the electricity storage module 4 , leakage of the electrolytic solution to the outside of the electricity storage module 4 can be suppressed while ensuring the rigidity of the entire electricity storage module 4 .

In the first embodiment, the crystallinity of the resin portion 22 joined to the metal plate 15 of the negative terminal electrode 18 is lower than the crystallinity of the resin portion 21 joined to the metal plate 15 of the bipolar electrode 14. there is The resin portion 22 is joined to the peripheral portion 15 c of the metal plate 15 of the negative terminal electrode 18 . However, when the electrolyte contains an alkaline solution, the electrolyte runs along the surface of the metal plate 15 of the negative terminal electrode 18 and passes between the resin part 22 and the metal plate 15 due to the so-called alkali creep phenomenon, and the power storage module There is a possibility that it will seep out to the outside of 4. If the electrolyte leaks and diffuses to the outside of the storage module 4 , for example, corrosion of the metal plate 15 arranged in contact with the storage module 4 or a short circuit between the storage module 4 and the binding member 3 may occur. In addition to the internal pressure of the internal space V, stress due to the alkali creep phenomenon is applied to the resin portion 22 . In this respect, since the degree of crystallinity of the resin portion 22 is lower than that of the resin portion 23 , at least cracks due to residual stress are less likely to occur in the resin portion 22 than in the resin portion 23 . Therefore, even if stress due to the alkali creep phenomenon is applied to the resin portion 22 in addition to the internal pressure of the internal space V, leakage of the electrolytic solution to the outside of the power storage module 4 can be suppressed.

In the first embodiment, the crystallinity of the resin portion 23 joined to the metal plate 15 of the positive terminal electrode 19 is higher than the crystallinity of the resin portion 22 joined to the metal plate 15 of the negative terminal electrode 18. ing. On the side of the positive terminal electrode 19, the occurrence of cracks in the resin portion 23 has a low relationship with leakage of the electrolytic solution due to the alkaline creep phenomenon. If the degree of crystallinity of resin portion 23 is higher than the degree of crystallinity of resin portion 22 , resin portion 23 has at least higher rigidity than resin portion 22 . Therefore, in this electricity storage module 4, the rigidity of the entire electricity storage module can be further improved while preventing the electrolyte from leaking out of the electricity storage module 4 due to the alkaline creep phenomenon.

In the modified example of the first embodiment, the degree of crystallinity of the resin portion 23 joined to the metal plate 15 of the positive terminal electrode 19 is lower than the degree of crystallinity of the resin portion 21 . In this case, cracks due to residual stress are less likely to occur at least in the resin portion 23 than in the resin portion 21 . Therefore, even if stress due to the internal pressure of the internal space V is applied to the resin portion 23 , leakage of the electrolytic solution to the outside of the power storage module 4 can be suppressed.

In the first embodiment, the resin portions 21 and 23 and the resin portion 22 are made of different materials, and the material of the resin portion 22 is less likely to crystallize than the material of the resin portions 21 and 23. material. In this case, it is possible to easily realize a structure in which the degree of crystallinity of resin portion 22 is lower than that of resin portion 21 and the degree of crystallinity of resin portion 23 is higher than that of resin portion 22 .

In the modified example of the first embodiment, the resin portion 23 and the resin portion 21 are made of different materials, and the material of the resin portion 23 is less likely to crystallize than the material of the resin portion 21 . In this case, a structure in which the degree of crystallinity of the resin portion 23 is lower than that of the resin portion 21 can be easily realized.

In the first embodiment, resin portion 21 and resin portion 23 contain homopolymer polypropylene, and resin portion 22 contains random or block copolymer polypropylene. Random or block copolymer polypropylene is less likely to crystallize than homopolymer polypropylene. Therefore, a structure in which the crystallinity of the resin portion 22 is lower than that of the resin portion 21 and the crystallinity of the resin portion 23 is higher than that of the resin portion 22 can be easily realized. As a result, while the generation of cracks in resin portion 22 is suppressed, the rigidity of the entire power storage module can be ensured in resin portions 21 and 23 . In addition, since homopolymer polypropylene is contained in the resin portion 21 and the resin portion 23, it is possible to suppress leakage of additives such as hindered phenol added to the resin body.

In a variant of the first embodiment, resin portion 21 contains homopolymer polypropylene, and resin portions 22 and 23 contain random copolymer or block copolymer polypropylene. In this case, a structure in which the degree of crystallinity of the resin portion 23 is lower than that of the resin portion 21 can be easily realized.

The resin portion 22 and the resin portion 23 have a facing surface 25 that faces the resin portion 21 . The facing surface 25 includes a region K1 bonded to the metal plate 15 and a region K2 not bonded to the metal plate 15 . In this case, as indicated by arrows A1 and A2 in FIG. It shrinks more than the region K1 where it is. Therefore, there is a problem that residual stress tends to occur in the resin portions 22 and 23 .

In addition, the metal plate 15 is roughened in the joint regions K3 between the metal plate 15 and the resin portions 22 and 23 . In this case, the bonding strength between the resin portions 22 and 23 and the metal plate 15 is improved by the anchor effect. Therefore, peeling of the resin portion 22 and the resin portion 23 can be further suppressed, and leakage of the electrolyte due to the peeling of the resin portion 22 and the resin portion 23 can be suppressed. In particular, since the metal plate 15 of the negative electrode terminal electrode 18 is roughened in the joint region K3 between the metal plate 15 of the negative electrode terminal electrode 18 and the resin portion 22, the alkali creep phenomenon due to peeling of the resin portion 22 is prevented from progressing. can be suppressed. However, due to the occurrence of the anchor effect, the above-mentioned problem due to the difference in shrinkage between the region K2 not bonded to the metal plate 15 and the region K1 bonded to the metal plate 15 may become more pronounced.

In the first embodiment, in the electricity storage module 4, the resin portion 22 has a relatively low degree of crystallinity. Even if there is, the occurrence of residual stress in the resin portion 22 is suppressed. Therefore, cracks due to residual stress are less likely to occur in the resin portion 22 . Further, in the modified example of the first embodiment, the resin portion 23 also has a relatively low degree of crystallinity. Even if there is, the occurrence of residual stress in the resin portion 23 is suppressed. Therefore, cracks due to residual stress are less likely to occur in the resin portion 23 as well.

Next, a power storage module according to another modification of the first embodiment will be described. This variation is generally similar or the same as the embodiment described above. This modification is similar to the embodiment described above with respect to the point that the resin portion 21, the resin portion 22, and the resin portion 23 are made of the same material, and the difference in crystallinity of the resin portion is caused by the difference in the cooling rate. differ from Differences from the above-described embodiment will be mainly described below.

In this modification, the difference in crystallinity between the resin portion 21 , the resin portion 22 , and the resin portion 23 is due to cooling when the resin portion 21 , the resin portion 22 , and the resin portion 23 are each bonded to the metal plate 15 . brought about by the difference in speed. When the resin body is made of the same material, the faster the cooling rate of the resin body, the lower the degree of crystallinity after cooling. Manufacturing costs can be reduced if the resin portion 21, the resin portion 22, and the resin portion 23 are manufactured from the same material.

In this modification, the crystallinity of the resin portion 22 is lower than the crystallinity of the resin portions 21 and 23 . In other words, the degree of crystallinity of the resin portion 21 and the degree of crystallinity of the resin portion 23 is higher than the degree of crystallinity of the resin portion 22 . In this modification, the difference in crystallinity between the resin portion 22 and the resin portion 21 is caused by the difference in cooling rate.

In this modification, the resin portion 21, the resin portion 22, and the resin portion 23 are made of the same material, and contain homopolymer polypropylene as a main constituent material. The resin portion 21, the resin portion 22, and the resin portion 23 may contain random copolymer polypropylene as a main constituent material. The resin portion 21, the resin portion 22, and the resin portion 23 may contain block copolymer polypropylene as a main constituent material. The melting point of block copolymer polypropylene is higher than that of random copolymer polypropylene. Therefore, when the main constituent material of the resin portion 21, the resin portion 22, and the resin portion 23 is a block copolymer polypropylene, the sealing body 12 is formed more easily and reliably than in the case of a random copolymer polypropylene. obtain.

In the method for manufacturing the electricity storage module 4 in this modified example, in the first forming step, the second forming step, and the third forming step, the degree of crystallinity after the bonding of the resin portion 22 is the same as that of the resin portion 21 and the resin portion 23 . It is implemented so that the degree of crystallinity after bonding is lower than that of . In this modified example, the difference in the crystallinity of the resin portion 21, the resin portion 22, and the resin portion 23 is the difference in the cooling rate when the resin portion 21, the resin portion 22, and the resin portion 23 are bonded to the metal plate 15. brought about by

In this modified example, the cooling rate during bonding of the resin portion 22 in the first forming process is faster than the cooling rate during bonding of the resin portion 21 in the second forming process. As a result, even if the same material is used for the resin portion 21 and the resin portion 22, the crystallinity of the resin portion 22 after the resin body is cooled is the same as that of the resin portion 22 after the resin body is cooled. can be formed below the crystallinity of Therefore, while the rigidity of the entire power storage module 4 is ensured, leakage of the electrolytic solution to the outside of the power storage module 4 can be suppressed.

In this modified example, the cooling rate during bonding of the resin portion 23 in the second forming process is slower than the cooling rate during bonding of the resin portion 22 in the first forming process. As a result, even if the same material is used for the resin portion 22 and the resin portion 23, the crystallinity of the resin portion 23 after the resin body is cooled is the same as that of the resin portion 23 after the resin body is cooled. can be formed higher than the crystallinity of If the degree of crystallinity of resin portion 23 is higher than the degree of crystallinity of resin portion 22 , resin portion 23 has at least higher rigidity than resin portion 22 . Therefore, in this electricity storage module 4, the rigidity of the entire electricity storage module can be further improved while preventing the electrolyte from leaking out of the electricity storage module 4 due to the alkaline creep phenomenon.

As yet another modification, when the crystallinity of the resin portion 23 is lower than that of the resin portion 21, the first forming step, the second forming step, and the third forming step are performed after bonding the resin portion 23. It is performed so that the degree of crystallinity is lower than the degree of crystallinity after bonding of the resin portion 21 . In this case, for example, the cooling rate during bonding of the resin portion 23 in the second forming step may be faster than the cooling speed during bonding of the resin portion 21 in the third forming step. As a result, even if the same material is used for the resin portion 21 and the resin portion 23, the degree of crystallinity of the resin portion 23 after the resin body is cooled is the same as that of the resin portion 23 after the resin body is cooled. can be formed below the crystallinity of Therefore, even if stress due to the internal pressure of the internal space V is applied to the resin portion 23 , leakage of the electrolytic solution to the outside of the power storage module 4 can be suppressed.
[Second embodiment]

Next, a power storage module according to a second embodiment will be described with reference to FIG. The second embodiment is generally similar or the same as the first embodiment and variations of the first embodiment described above. The second embodiment differs from the above-described first embodiment and its modification in that end plates are arranged outside the negative terminal electrode 18 and the positive terminal electrode 19 . Differences from the above-described first embodiment and its modification will be mainly described below. FIG. 7 is a schematic cross-sectional view showing the internal configuration of the power storage module according to the second embodiment.

In the power storage module 4A of the second embodiment, the metal plate 50 is arranged outside the metal plate 15 included in the negative terminal electrode 18 in the stacking direction D. As shown in FIG. A metal plate 60 is arranged outside the metal plate 15 included in the positive terminal electrode 19 in the stacking direction D. As shown in FIG. In the second embodiment, the metal plate 50 constitutes one of the pair of end plates, and the metal plate 60 constitutes the other of the pair of end plates. The metal plate 50 is the outermost metal plate on the negative electrode side, and the metal plate 60 is the outermost metal plate on the positive electrode side. The metal plates 50 and 60 are plate-like members provided for suppressing deterioration of the electrode laminate 11, and exhibit conductivity and flexibility.

The one surface 50a and the other surface 50b of the metal plate 50 and the one surface 60a and the other surface 60b of the metal plate 60 are not coated with the positive electrode active material and the negative electrode active material. Therefore, the entire surfaces of the one surfaces 50a, 60a and the other surfaces 50b, 60b are uncoated areas. The one surfaces 50a and 60a are surfaces facing the conductive structure 5 in the stacking direction D. As shown in FIG. The other surfaces 50b and 60b are located on the opposite sides of the one surfaces 50a and 60a in the stacking direction D and face the electrode stack 11 . The other surface 50 b faces the negative terminal electrode 18 and the other surface 60 b faces the positive terminal electrode 19 . The metal plate 50 can also have a function of suppressing the outflow of the electrolytic solution through the gap between the negative terminal electrode 18 and the sealing body 12 . The metal plate 60 can also have a function of suppressing the outflow of the electrolytic solution through the gap between the positive terminal electrode 19 and the sealing body 12 .

The metal plates 50 and 60 have central portions 51 and 61 in contact with the conductive structure 5 and peripheral edge portions 52 and 62 surrounding the central portions 51 and 61 in plan view. The center portion 51 of the metal plate 50 is depressed toward the center of the electrode laminate 11 and pressed against the negative terminal electrode 18 by the binding force of the binding member 3 applied to the electrode laminate 11 via the conductive structure 5 . there is Similarly, the central portion 61 of the metal plate 60 is depressed toward the center of the electrode stack 11 and pressed against the positive terminal electrode 19 . Thereby, the central portion 51 contacts the negative terminal electrode 18, and the metal plate 50 can function as a negative terminal in the power storage module 4A. The central portion 61 contacts the positive terminal electrode 19, and the metal plate 60 can function as a positive terminal in the power storage module 4A.

The peripheral edge portions 52 and 62 are portions separated from the negative terminal electrode 18 and the positive terminal electrode 19 . A portion 52 a of the peripheral edge portion 52 is a portion held by the resin portion 22 and a resin portion 71 to be described later, and is positioned outside the central portion 51 in the stacking direction D. As shown in FIG. A portion 62a of the peripheral portion 62 is a portion held by the resin portion 23 and a resin portion 72 described later, and is positioned outside the central portion 61 in the stacking direction D. As shown in FIG. The other portion 52b of the peripheral portion 52 is a portion that connects the portion 52a and the central portion 51, and is positioned closer to the center of the metal plate 50 than the sealing member 12 in the horizontal direction. The other portion 62b of the peripheral portion 62 is a portion that connects the portion 62a and the central portion 61, and is positioned closer to the center of the metal plate 60 than the sealing body 12 in the horizontal direction. Like the metal plate 15, the metal plates 50, 60 are made of metal such as nickel or nickel-plated steel plate.

In the second embodiment, the sealing body 12 holds the peripheral portion 15c of the metal plate 15, a portion 52a of the peripheral portion 52 of the metal plate 50, and a portion 62a of the peripheral portion 62 of the metal plate 60. ing. In the second embodiment, the sealing body 12 has a resin portion 71 and a resin portion 72 in addition to the resin portions 21 , 22 and 23 . The resin portion 71 is provided continuously over the entire circumference of the portion 52a of the peripheral portion 52 in the metal plate 50, and has a rectangular frame shape when viewed from the stacking direction D. As shown in FIG. The resin portion 72 is provided continuously over the entire circumference of the portion 62a of the peripheral edge portion 62 in the metal plate 60, and has a rectangular frame shape when viewed from the stacking direction D. As shown in FIG.

In the second embodiment, for example, the resin portion 71 is the negative electrode side terminal resin portion, the resin portion 72 is the positive electrode side terminal resin portion, and the resin portion 21 is the intermediate resin portion. For example, the negative terminal resin portion is bonded to one peripheral edge portion 52 of the pair of end plates, the positive electrode terminal resin portion is bonded to the other peripheral edge portion 62 of the pair of end plates, and the intermediate resin portion is bonded to the bipolar electrode 14. It is joined to the peripheral portion 15 c of the metal plate 15 .

The resin portion 71 faces the resin portion 22 , and the resin portion 72 faces the resin portion 23 . Therefore, the resin portions 71 and 72 also have facing surfaces 25 that face adjacent resin portions in the same manner as the resin portions 21 , 22 and 23 . The resin portion 71 is joined to the one surface 50 a of the metal plate 50 on the opposing surface 25 . The resin portion 71 also includes a region K<b>1 bonded to the metal plate 50 and a region K<b>2 not bonded to the metal plate 50 on the facing surface 25 . The resin portion 72 is joined to the one surface 60 a of the metal plate 60 on the opposing surface 25 . The resin portion 72 also includes a region K<b>1 bonded to the metal plate 60 and a region K<b>2 not bonded to the metal plate 60 on the facing surface 25 .

The surfaces of the metal plates 50 and 60 are roughened in the bonding regions K3 where they are bonded to the resin portions 71 and 72, respectively. The roughened region may be only the joint region K3, but in the second embodiment, the entire surfaces of the metal plates 50 and 60 are roughened. Roughening can be achieved by forming a plurality of protrusions by, for example, electroplating. By forming a plurality of protrusions, at the joint interface between the metal plates 50 and 60 and the resin portion 71 and the resin portion 72, the resin in a molten state enters between the plurality of protrusions formed by roughening the surface, resulting in an anchor effect. is exhibited. Thereby, the bonding strength between the metal plates 50 and 60 and the resin portions 71 and 72 can be improved. The projections formed during surface roughening have, for example, a shape that tapers from the proximal side to the distal side. As a result, the cross-sectional shape between adjacent projections becomes an undercut shape, making it possible to enhance the anchor effect.

The resin portion 71 and the resin portion 72 are welded to the metal plates 50 and 60 by heat and are airtightly joined. The resin portion 71 and the resin portion 72 are films having a predetermined thickness in the stacking direction D, for example. The inner sides of the resin portions 71 and 72 are positioned so as to overlap the peripheral edge portions 52 and 62 of the metal plates 50 and 60 when viewed from the stacking direction D. As shown in FIG. The outer sides of the resin portion 71 and the resin portion 72 protrude beyond the edges of the metal plates 50 and 60 , and their tip portions are supported by the housing portion 24 . In the stacking direction D, the resin portion 71 is in contact with the resin portion 22 , and the resin portion 72 is in contact with the resin portion 23 . Further, the outer edge portions of the resin portion 71 and the resin portion 22 and the outer edge portions of the resin portion 72 and the resin portion 23 may be joined to each other by hot plate welding, for example.

The housing portion 24 is provided outside the resin portion 71 and the resin portion 72, and constitutes an outer wall of the power storage module 4A. The housing part 24 is formed, for example, by injection molding of resin, and extends along the stacking direction D over the entire length of the electrode stack 11 . The housing part 24 has a rectangular frame shape extending with the stacking direction D as an axial direction. The housing portion 24 is welded to the outer surface of the resin portion 21 by heat during injection molding, for example.

The resin portion 71 and the resin portion 72 are, for example, an insulating resin having alkali resistance. In the second embodiment, main constituent materials of the resin portion 71 and the resin portion 72 include, for example, polypropylene (PP), polyphenylene sulfide (PPS), modified polyphenylene ether (modified PPE), and the like. Polypropylene includes, for example, homopolymers of homopolymerization, and random and block copolymers of copolymerization. For example, an additive having an antioxidant function may be added to the resin portion 71 and the resin portion 72 . Additives having an antioxidant function include, for example, hindered phenols.

In the second embodiment, the resin portion 22 is arranged between the peripheral portion 15 c of the metal plate 15 of the negative terminal electrode 18 and the portion 52 a of the peripheral portion 52 of the metal plate 50 and the resin portion 71 . Moreover, the metal plate 15 , the resin portion 22 , and the metal plate 50 of the negative terminal electrode 18 are hermetically sealed by the housing portion 24 . Therefore, the negative terminal electrode 18 , the metal plate 50 , and the resin portion 22 form an extra space EV.

In the second embodiment, the resin portion 23 is arranged between the peripheral portion 15 c of the metal plate 15 of the positive terminal electrode 19 and the portion 62 a of the peripheral portion 62 of the metal plate 60 and the resin portion 72 . Moreover, the metal plate 15 , the resin portion 23 , and the metal plate 60 of the positive terminal electrode 19 are hermetically sealed by the housing portion 24 . Therefore, the surplus space EV is formed by the positive terminal electrode 19 , the metal plate 60 and the resin portion 23 .

In the second embodiment, the crystallinity of the resin portion 71 is lower than the crystallinity of the resin portions 21 , 22 , 23 and the resin portion 72 . In other words, the crystallinity of the resin portions 21 , 22 , 23 and the resin portion 72 is higher than the crystallinity of the resin portion 71 . The difference in the degree of crystallinity of the resin portion is brought about by the difference in materials and the difference in bonding conditions, such as the difference in cooling rate. In the second embodiment, the difference in crystallinity between the resin portion 71, the resin portion 72, and the resin portions 21, 22, and 23 is the difference in the materials of the resin portion 71, the resin portion 72, and the resin portions 21, 22, and 23. brought about by

In the second embodiment, the degree of crystallinity of the resin portion 72 is equal to the degree of crystallinity of the resin portions 21, 22, and 23, but is not limited to this. The crystallinity of at least one of the resin portions 71 and 72 may be lower than the crystallinity of the resin portions 21 , 22 and 23 . For example, as a modification of the second embodiment, the crystallinity of the resin portion 72 may be lower than the crystallinity of the resin portions 21 , 22 , 23 . In this modification, the degree of crystallinity of resin portion 72 may be equal to the degree of crystallinity of resin portion 71 .

In the second embodiment, the resin portion 71, the resin portions 21, 22, 23, and the resin portion 72 are made of different materials. The material of the resin portion 71 is a material that is less likely to crystallize than the material of the resin portions 21 , 22 , 23 and the resin portion 72 . The resin portions 21, 22, 23 and the resin portion 72 contain homopolymer polypropylene as a main constituent material. The resin portion 71 contains random copolymer or block copolymer polypropylene as a main constituent material. The melting point of block copolymer polypropylene is higher than that of random copolymer polypropylene. Therefore, when the main constituent material of the resin portion 71 is a block copolymer polypropylene, the encapsulant 12 can be formed more easily and reliably than when it is a random copolymer polypropylene. As a result, product reliability is improved.

In the second embodiment, the resin portions 21, 22, 23 and the resin portion 72 are made of the same material, but are not limited to this. At least one of the resin portion 71 and the resin portion 72 and the resin portions 21, 22, and 23 may be made of different materials. The material of the resin portions 21 , 22 , 23 may be a material that is less likely to crystallize than the material of at least one of the resin portions 71 and 72 . For example, in the modified example of the second embodiment described above, the resin portion 72 and the resin portions 21, 22, and 23 may be made of different materials, and the material of the resin portions 21, 22, and 23 may be the material of the resin portion 72. It may be a material that is more difficult to crystallize.

In the second embodiment, the resin portions 21, 22, 23 and the resin portion 72 contain homopolymer polypropylene as the main material, and the resin portion 71 contains random copolymer or block copolymer polypropylene as the main constituent material. , but not limited to. At least one of the resin portion 71 and the resin portion 72 may contain random copolymer or block copolymer polypropylene. For example, in the modification of the second embodiment described above, the resin portions 21, 22, and 23 contain homopolymer polypropylene, and the resin portions 71 and 72 contain random copolymer or block copolymer polypropylene. good too.

Next, an example of a method for manufacturing the electricity storage module 4A according to the second embodiment will be described, mainly focusing on differences from the explanation of the electricity storage module 4 according to the first embodiment.

In the second embodiment, in the step of forming the resin portion 71 and the resin portion 72, the degree of crystallinity after bonding the resin portion 71 is higher than the degree of crystallinity after bonding the resin portions 21, 22, 23 and the resin portion 72. implemented to be low. In other words, in the step of forming the resin portion 71 and the resin portion 72, the degree of crystallinity after crystallization of the resin portions 21, 22, 23 and the resin portion 72 is higher than the degree of crystallinity after crystallization of the resin portion 71. It is implemented so that

In the second embodiment, the step of forming the resin portion 72 is performed so that the crystallinity of the resin portion 72 after bonding is equal to the crystallinity of the resin portions 21, 22, and 23 after bonding. is not limited to The step of forming the resin portion 71 and the resin portion 72 is performed so that the degree of crystallinity after bonding of at least one of the resin portion 71 and the resin portion 72 is lower than the degree of crystallinity after bonding the resin portions 21 , 22 , and 23 . may be implemented. For example, in the modified example of the second embodiment described above, in the step of forming the resin portion 72, the degree of crystallinity after bonding the resin portion 72 becomes lower than the degree of crystallinity after bonding the resin portions 21, 22, and 23. may be implemented as follows. In this modification, the step of forming the resin portion 71 and the resin portion 72 may be performed so that the degree of crystallinity after bonding of the resin portion 72 is equal to the degree of crystallinity after bonding of the resin portion 71 .

In the second embodiment, the difference in crystallinity between the resin portion 71, the resin portion 72, and the resin portions 21, 22, and 23 is the difference in the materials of the resin portion 71, the resin portion 72, and the resin portions 21, 22, and 23. brought about by In the second embodiment, different materials are used for the resin portions 21 , 22 , 23 and the resin portion 72 and the resin portion 71 . A material that is less likely to crystallize than the material of the resin portions 21 , 22 , 23 and the resin portion 72 is used as the material of the resin portion 71 .

In the second embodiment, homopolymer polypropylene is used as the main constituent material of the resin portions 21 , 22 , 23 and the resin portion 72 . Random copolymer or block copolymer polypropylene is used as a main constituent material of the resin portion 71 . The melting point of block copolymer polypropylene is higher than that of random copolymer polypropylene. Therefore, when the main constituent material of the resin portion 71 is a block copolymer polypropylene, the encapsulant 12 can be formed more easily and reliably than when it is a random copolymer polypropylene.

In the second embodiment, the same material is used for the resin portions 21, 22, 23 and the resin portion 72, but the present invention is not limited to this. At least one of the resin portion 71 and the resin portion 72 and the resin portions 21, 22, and 23 may be made of different materials. A material that is less likely to crystallize than the material of at least one of the resin portions 71 and 72 may be used as the material of the resin portions 21 , 22 , and 23 . For example, in the modified example of the second embodiment described above, different materials may be used for the resin portion 72 and the resin portions 21, 22, and 23. A material that is less likely to crystallize than the material may be used.

In the second embodiment, homopolymer polypropylene is used as the main constituent material of the resin portions 21, 22, 23 and the resin portion 72, and random copolymer or block copolymer is used as the main constituent material of the resin portion 71. Polypropylene is used, but is not so limited. Random copolymer or block copolymer polypropylene may be used as a main constituent material of at least one of the resin portion 71 and the resin portion 72 . For example, in the modified example of the second embodiment described above, homopolymer polypropylene may be used as the constituent material of the resin portions 21, 22, and 23, and the constituent material of the resin portion 71 and the resin portion 72 is Random copolymer or block copolymer polypropylene may be used.

In power storage module 4</b>A, the crystallinity of at least one of resin portion 71 and resin portion 72 is lower than the crystallinity of resin portions 21 , 22 , and 23 . Therefore, in the electricity storage module 4A, at least one of the resin portion 71 and the resin portion 72 is less likely to crack due to residual stress than at least the resin portions 21 , 22 , and 23 . If the occurrence of cracks in at least one of the resin portions 71 and 72 is suppressed, leakage of the electrolytic solution to the outside of the power storage module 4A is also suppressed. Moreover, the rigidity of the entire power storage module 4A can be ensured by the resin portions 21 , 22 , 23 . That is, in the electricity storage module 4A, the leakage of the electrolytic solution to the outside of the electricity storage module 4A can be suppressed while ensuring the rigidity of the entire electricity storage module 4A.

A surplus space EV is formed in the power storage module 4A. The alkaline electrolyte accommodated in the internal space V may flow out of the power storage module through the gap between the resin portion 22 and the metal plate 15 of the negative terminal electrode 18 due to a so-called alkaline creep phenomenon. Since the electric storage module 4A includes the metal plate 50 located outside the negative terminal electrode 18 in the stacking direction D, the surplus space EV is formed. Therefore, the outflowing alkaline electrolyte is suppressed from leaking out of the power storage module 4A. In addition, entry of moisture contained in the outside air through the gap between the negative terminal electrode 18 and the resin portion 71 is also suppressed. As a result, the acceleration of the alkali creep phenomenon caused by the moisture is suppressed. Therefore, the outflow of the alkaline electrolyte to the outside of the power storage module 4A is suppressed satisfactorily.

In the second embodiment, the crystallinity of the resin portion 71 joined to the metal plate 50 on the negative terminal electrode 18 side is lower than the crystallinity of the resin portions 21 , 22 , 23 . Therefore, even if stress due to the alkali creep phenomenon is applied to the resin portion 71 in addition to the internal pressure of the internal space V, leakage of the electrolytic solution to the outside of the power storage module 4A can be suppressed.

In the second embodiment, the crystallinity of the resin portion 72 joined to the metal plate 60 on the positive terminal electrode 19 side is higher than the crystallinity of the resin portion 71 . On the side of the positive terminal electrode 19, the occurrence of cracks in the resin portion 72 has little relationship with leakage of the electrolytic solution due to the alkaline creep phenomenon. If the degree of crystallinity of resin portion 72 is higher than the degree of crystallinity of resin portion 71 , resin portion 72 has at least higher rigidity than resin portion 71 . Therefore, in this electricity storage module 4A, the rigidity of the entire electricity storage module can be further improved while preventing the electrolyte from leaking out of the electricity storage module 4A due to the alkaline creep phenomenon.

In the modified example of the second embodiment, the crystallinity of the resin portion 72 joined to the metal plate 60 on the positive terminal electrode 19 side is lower than the crystallinity of the resin portion 21 . In this case, cracks due to residual stress are less likely to occur in the resin portion 72 than at least in the resin portion 21 . Therefore, even if stress due to the internal pressure of the internal space V is applied to the resin portion 72, leakage of the electrolytic solution to the outside of the power storage module 4A can be suppressed.

In the second embodiment, the resin portions 21, 22, 23 and the resin portion 72 and the resin portion 71 are made of different materials. The material of the resin portion 71 is a material that is less likely to crystallize than the material of the resin portions 21 , 22 , 23 and the resin portion 72 . In this case, a structure in which the crystallinity of resin portion 71 is lower than that of resin portions 21 , 22 , and 23 and the crystallinity of resin portion 72 is higher than that of resin portion 71 can be easily realized.

In the modification of the second embodiment, the resin portion 72 and the resin portions 21, 22, and 23 are made of different materials, and the material of the resin portion 72 is less likely to crystallize than the material of the resin portions 21, 22, and 23. material. In this case, a structure in which the degree of crystallinity of the resin portion 72 is lower than that of the resin portions 21, 22, and 23 can be easily realized.

As described above, the first and second embodiments and modifications of the present invention have been described, but the present invention is not necessarily limited to the first and second embodiments and modifications described above, and the gist thereof is Various changes are possible without departing from the scope.

For example, in the second embodiment, all or part of the resin portion 21, the resin portion 22, the resin portion 23, the resin portion 71, and the resin portion 72 are made of the same material, and the modification of the first embodiment described above is used. Thus, the difference in crystallinity of the resin portion may be caused by the difference in cooling rate.

In the power storage module 4A having the metal plates 50 and 60 and the resin portions 71 and 72 as in the second embodiment, the above-described first embodiment and the modifications described accompanying it can be achieved in accordance with the various functions and effects described above. As in the example, the resin parts 21, 22, 23 may have different crystallinity, different materials, and different cooling rates.

In the above-described first and second embodiments and modifications, the difference in crystallinity among the resin portion 21, the resin portion 22, the resin portion 23, the resin portion 71, and the resin portion 72 is the difference in the cooling rate and the material. I explained the case brought about by either one of the differences in However, the difference in crystallinity between the resin portion 21, the resin portion 22, the resin portion 23, the resin portion 71, and the resin portion 72 may be brought about by a combination of the difference in cooling rate and the difference in material.

4, 4A... Electricity storage module 11... Electrode laminate 11a... Side surface 12... Sealing body 14... Bipolar electrode 15, 50, 60... Metal plate 15c, 52, 62... Peripheral part 16... Positive electrode, 17 Negative electrode 18 Negative electrode terminal electrode 19 Positive electrode terminal electrode 21, 22, 23, 71, 72 Resin portion 25 Opposing surface D Lamination direction K1, K2 Area K3 Joining area V... Internal space.

Claims (17)

an electrode laminate having a pair of metal end plates and a plurality of bipolar electrodes laminated between the pair of end plates;
a sealing body provided so as to surround the side surface of the electrode laminate;
and an electrolytic solution contained between the adjacent bipolar electrodes,
Each of the plurality of bipolar electrodes includes a metal plate, a positive electrode provided on one side of the metal plate, and a negative electrode provided on the other side of the metal plate,
The sealing body includes a terminal resin portion bonded to the peripheral edge portion of at least one of the pair of end plates, and an intermediate resin portion bonded to the peripheral edge portion of the metal plate of the bipolar electrode,
The power storage module, wherein the crystallinity of the terminal resin portion is lower than the crystallinity of the intermediate resin portion. the terminal resin portion and the intermediate resin portion are made of different materials,
The power storage module according to claim 1, wherein the terminal resin portion is made of a material that is less likely to crystallize than the material of the intermediate resin portion. The intermediate resin portion contains homopolymer polypropylene,
The electricity storage module according to claim 1 or 2, wherein the terminating resin portion contains polypropylene of random copolymer or block copolymer. 2. The power storage module according to claim 1, wherein said terminal resin portion and said intermediate resin portion are made of the same material. one of the pair of end plates is a metal plate of a negative terminal electrode having a negative electrode provided on one side of the metal plate and the metal plate;
The electrolytic solution contains an alkaline solution,
The power storage module according to any one of claims 1 to 4, wherein the termination resin portion has a negative electrode side termination resin portion joined to a peripheral edge portion of the metal plate of the negative electrode termination electrode. The electrolytic solution contains an alkaline solution,
One of the pair of end plates is a negative electrode-side outermost metal plate disposed outside a negative terminal electrode having a negative electrode provided on one side of a metal plate and a negative electrode provided on one side of the metal plate in the stacking direction of the electrode laminate. can be,
The power storage module according to any one of claims 1 to 4, wherein the termination resin portion includes a negative electrode side termination resin portion joined to a peripheral edge portion of the negative electrode side outermost metal plate. The other of the pair of end plates is a metal plate of a positive terminal electrode having a metal plate and a positive electrode provided on one surface of the metal plate,
The termination resin portion includes a positive electrode side termination resin portion joined to a peripheral edge portion of the metal plate of the positive electrode termination electrode,
The power storage module according to claim 5 or 6, wherein the positive electrode side termination resin portion has a higher crystallinity than the negative electrode side termination resin portion. The other of the pair of end plates is a positive electrode side outermost metal plate disposed outside a positive terminal electrode having a positive electrode provided on one side of the metal plate and the metal plate in the stacking direction of the electrode laminate. can be,
The termination resin portion has a positive electrode side termination resin portion joined to a peripheral edge portion of the positive electrode side outermost metal plate,
7. The power storage module according to claim 5, wherein the positive electrode side termination resin portion has a higher crystallinity than the negative electrode side termination resin portion. The terminal resin portion has a facing surface facing the intermediate resin portion,
The power storage module according to any one of claims 1 to 8, wherein said facing surface includes a region that is bonded to said end plate and a region that is not bonded to said end plate. The power storage module according to any one of claims 1 to 9, wherein the end plate is roughened in a joint region between the terminal resin portion and the end plate. An electrode laminate in which a plurality of bipolar electrodes including a metal plate, a positive electrode provided on one side of the metal plate, and a negative electrode provided on the other side of the metal plate are laminated between a pair of metal end plates. A method for manufacturing an electricity storage module having
an outermost layer forming step of joining a terminating resin portion to a peripheral portion of at least one of the pair of end plates;
an intermediate layer forming step of joining an intermediate resin portion to a peripheral portion of the metal plate of the bipolar electrode;
A method of manufacturing an electricity storage module, wherein the outermost layer forming step and the intermediate layer forming step are performed such that the degree of crystallinity after bonding of the terminal resin portion is lower than the degree of crystallinity after bonding of the intermediate resin portion. . Using different materials for the terminal resin portion and the intermediate resin portion,
12. The method of manufacturing an electric storage module according to claim 11, wherein a material that is less likely to crystallize than a material of the intermediate resin portion is used as the material of the terminal resin portion. Using homopolymer polypropylene as the intermediate resin part,
13. The method of manufacturing an electricity storage module according to claim 11, wherein the terminating resin portion is made of random copolymer or block copolymer polypropylene. using the same material for the terminal resin portion and the intermediate resin portion,
12. The manufacturing method according to claim 11, wherein a cooling rate during bonding of the terminal resin portion is set faster than a cooling rate during bonding of the intermediate resin portion. one of the pair of end plates is a negative terminal electrode having a metal plate and a negative electrode provided on one surface of the metal plate;
In the outermost layer forming step, a negative electrode side termination resin portion as the termination resin portion is joined to a peripheral edge portion of the metal plate of the negative electrode termination electrode,
12. The outermost layer forming step and the intermediate layer forming step are performed such that the degree of crystallinity after bonding of the negative electrode-side terminal resin portion is lower than the degree of crystallinity after bonding of the intermediate resin portion. 15. The method for manufacturing the electricity storage module according to any one of 14. One of the pair of end plates is a negative electrode-side outermost metal plate disposed outside a negative terminal electrode having a negative electrode provided on one side of a metal plate and a negative electrode provided on one side of the metal plate in the stacking direction of the electrode laminate. can be,
In the outermost layer forming step, a negative electrode side termination resin portion as the termination resin portion is joined to a peripheral edge portion of the negative electrode side outermost metal plate in the stacking direction,
The outermost layer forming step and the intermediate layer forming step are performed such that the crystallinity after bonding of the negative electrode-side terminal resin portion is lower than the crystallinity after bonding of the intermediate resin portion. 15. The method for manufacturing the power storage module according to any one of 14. The other of the pair of end plates is a metal plate of a positive terminal electrode having a metal plate and a positive electrode provided on one surface of the metal plate,
In the outermost layer forming step, a positive electrode side termination resin portion as the termination resin portion is joined to a peripheral edge portion of the metal plate of the positive electrode termination electrode,
17. The outermost layer forming step according to claim 15 or 16, wherein the outermost layer forming step is performed so that the crystallinity after bonding of the positive electrode side termination resin portion is higher than the crystallinity after bonding of the negative electrode side termination resin portion. of the storage module.

Images