Power storage module and manufacturing method of power storage module

Abstract

To provide a power storage module capable of appropriately suppressing infiltration of moisture by suppressing short-circuiting, and a manufacturing method of a power storage module.SOLUTION: A power storage module comprises: a laminate including a plurality of laminated electrodes; and a sheath body which is formed from a pair of sheet members joined to each other so as to envelope the laminate and encapsulates the laminate inside. The plurality of electrodes includes: a cathode termination electrode including a cathode active material layer provided on one face of a collector; an anode termination electrode including an anode active material layer provided on the other face of the collector; and a bipolar electrode disposed between the cathode termination electrode and the anode termination electrode. Each of the pair of sheet members includes a peeling part in which each of a pair of insulation layers is partially peeled from a metal layer disposed between the pair of insulation layers. The peeling part in one of the pair of sheet member is disposed so as to be opposed with the anode termination electrode, and the peeling part in the other of the pair of sheet members is disposed so as to be opposed with the cathode termination electrode.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a power storage module and a method for manufacturing the power storage module.

Background Art

[0002] In a non-aqueous secondary battery in which the electrolyte is composed of a non-aqueous electrolyte, it is known that the battery performance deteriorates due to the intrusion of moisture into the battery. Specifically, when moisture enters the battery, the electrolyte may deteriorate and the resistance may increase, or the active material and the film may be decomposed by the deteriorated components, resulting in a decrease in battery performance. Therefore, in a non-aqueous secondary battery, it is important to ensure the airtightness of the battery exterior in order to suppress the intrusion of moisture such as atmospheric humidity. As an example of a non-aqueous secondary battery, Patent Document 1 discloses a power storage module having a laminate including a bipolar electrode and terminal electrodes of positive and negative electrodes.

[0003] The power storage module described in Patent Document 1 includes a laminate having an outer surface, and a sheet member provided in close contact with the laminate so as to cover the outer surface in a cross-section along the stacking direction of the laminate. The laminate includes a current collector having one surface and the other surface in the stacking direction, and at least one of a positive electrode active material layer and a negative electrode active material layer. A plurality of current collectors are stacked such that one surface faces the same direction along the stacking direction to form a plurality of electrodes, and a sealing portion that defines a space for accommodating an electrolyte together with the current collectors adjacent to each other in the stacking direction. The electrodes include a bipolar electrode having a positive electrode active material layer provided on one surface of the current collector and a negative electrode active material layer provided on the other surface of the current collector, a positive electrode terminal electrode having a positive electrode active material layer provided on one surface of the current collector and an exposed portion exposed from the sealing portion on the other surface of the current collector, and a negative electrode terminal electrode having a negative electrode active material layer provided on the other surface of the current collector and an exposed portion exposed from the sealing portion on one surface of the current collector. The sealing portion includes a plurality of frame-shaped first resin layers provided at the peripheral edges of the respective current collectors, a plurality of frame-shaped spacers arranged so as to be interposed between the first resin layers adjacent to each other in the stacking direction, and a second resin layer formed by welding the end portions on the opposite side of the spaces of the plurality of first resin layers and the plurality of spacers when viewed from the stacking direction. The outer surface includes a first surface that is the surface on the opposite side of the other surface of the current collector of the first resin layer provided on the other surface of the current collector of the positive electrode terminal electrode, a second surface that is the surface on the opposite side of the one surface of the current collector of the first resin layer provided on the one surface of the current collector of the negative electrode terminal electrode, and a third surface that is the surface on the opposite side of the space in the second resin layer and extends so as to connect the first surface and the second surface. The sheet member includes a metal layer and a first insulating layer laminated on the metal layer and disposed on the outer surface side of the metal layer. It extends from the first surface through the third surface to the second surface. The first end portion on the first surface of the sheet member and the second end portion on the second surface of the sheet member are located outside the inner edges of the first resin layer and the spacer and inside the outer edge of the current collector when viewed from the stacking direction. A first insulating member is provided from the first surface over the sheet member so as to cover the first end portion and is adhered to the first surface and the sheet member. A second insulating member is provided from the second surface over the sheet member so as to cover the second end portion and is adhered to the second surface and the sheet member.

[0004] In this power storage module, since a sheet member including a metal layer is provided so as to cover the outer surface of the laminate, Patent Document 1 describes that water intrusion into the laminate is suppressed as compared with the case where a sheet made of only a resin layer is provided.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] By the way, in a power storage device including a power storage module, a plurality of power storage modules may be stacked via a conductive member. In this case, adjacent power storage modules are electrically connected via a conductive member.

[0007] Therefore, for example, if the entire surface of the laminate is sealed with a sheet member including a resin layer, conduction between the laminate and the conductive member cannot be ensured. In order to ensure conduction between the laminate and the conductive member, it is conceivable to expose at least a part of the terminal electrodes of the positive and negative electrodes included in the laminate sealed with the sheet member outside the sheet member, as in the technique described in Patent Document 1. However, in such a configuration, moisture easily intrudes from between the end portion of the sheet member located at the exposed portion of the terminal electrodes of the positive and negative electrodes and the terminal electrodes of the positive and negative electrodes. Therefore, although the power storage module described in Patent Document 1 can suppress a short circuit by using a sheet member including a metal layer, there is a problem that moisture intrusion cannot be sufficiently suppressed.

[0008] The present disclosure has been made to solve such problems, and an object thereof is to provide a power storage module and a method for manufacturing a power storage module capable of suitably suppressing moisture intrusion while suppressing a short circuit.

Means for Solving the Problems

[0009] A power storage module according to an embodiment includes a laminate including a plurality of electrodes laminated along a stacking direction, and an exterior body formed by a pair of sheet members joined to each other so as to wrap the laminate and sealing the laminate inside. The plurality of electrodes each include a current collector having one surface and the other surface facing each other in the stacking direction and one surface facing the same direction along the stacking direction, a positive terminal electrode including a positive electrode active material layer provided on one surface of the current collector, a negative terminal electrode including a negative electrode active material layer provided on the other surface of the current collector so as to face the positive electrode active material layer, and at least one bipolar electrode disposed between the positive terminal electrode and the negative terminal electrode. Each of the pair of sheet members has a pair of insulating layers, a metal layer disposed between the pair of insulating layers, and a peeling portion in which a part of each of the pair of insulating layers is peeled off from the metal layer. One peeling portion of the pair of sheet members is disposed so as to face the negative terminal electrode, and the other peeling portion of the pair of sheet members is disposed so as to face the positive terminal electrode.

[0010] Also, a method for manufacturing a power storage module according to an embodiment includes a laminate manufacturing step of manufacturing a laminate including a plurality of electrodes laminated along a stacking direction, and a laminate sealing step of sealing the laminate inside an exterior body formed by a pair of sheet members joined to each other so as to wrap the laminate. The plurality of electrodes each include a current collector having one surface and the other surface facing each other in the stacking direction and one surface facing the same direction along the stacking direction, a positive terminal electrode including a positive electrode active material layer provided on one surface of the current collector, a negative terminal electrode including a negative electrode active material layer provided on the other surface of the current collector so as to face the positive electrode active material layer, and at least one bipolar electrode disposed between the positive terminal electrode and the negative terminal electrode. Each of the pair of sheet members has a pair of insulating layers, a metal layer disposed between the pair of insulating layers, and a peeling portion in which a part of each of the pair of insulating layers is peeled off from the metal layer. One peeling portion of the pair of sheet members is disposed so as to face the negative terminal electrode, and the other peeling portion of the pair of sheet members is disposed so as to face the positive terminal electrode.

Effects of the Invention

[0011] According to the present disclosure, it is possible to provide a power storage module capable of suitably suppressing intrusion of moisture while suppressing short circuits, and a method for manufacturing the power storage module.

Brief Description of the Drawings

[0012]

Figure 1

Figure 2

Figure 3

Figure 4

Modes for Carrying Out the Invention

[0013] Embodiment 1 Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. However, the present disclosure is not limited to the following embodiments. Also, for clarity of explanation, the following description and drawings are simplified as appropriate. In the following description, the same or equivalent elements are denoted by the same reference numerals, and overlapping descriptions are omitted.

[0014] Referring to FIGS. 1 and 2, the power storage module 1 according to Embodiment 1 will be described. FIG. 1 is a schematic cross-sectional view of the power storage module according to Embodiment 1. FIG. 2 is a perspective view of the power storage module shown in FIG. 1. The power storage module 1 shown in FIGS. 1 and 2 is used, for example, as a battery for various vehicles such as forklifts, hybrid vehicles, and electric vehicles. The power storage module 1 is, for example, a secondary battery such as a nickel-metal hydride secondary battery or a lithium-ion secondary battery. The power storage module 1 may be an electric double layer capacitor or an all-solid-state battery. In the present embodiment, the case where the power storage module 1 is a lithium-ion secondary battery is exemplified.

[0015] The storage module 1 has a laminate 10 and an exterior body 30. As shown in FIG. 1, the laminate 10 includes a plurality of electrodes laminated along the Z direction which is the lamination direction. The laminate 10 includes, in addition to the plurality of electrodes, a plurality of separators 14, a sealing portion 20, and an electrolyte (not shown). The plurality of electrodes have a plurality of bipolar electrodes 11, a negative terminal electrode 12, and a positive terminal electrode 13.

[0016] The bipolar electrode 11 has a current collector 15, a positive electrode active material layer 16, and a negative electrode active material layer 17. The current collector 15 has, for example, a rectangular sheet shape. The positive electrode active material layer 16 is provided on one surface 15a of the current collector 15. The negative electrode active material layer 17 is provided on the other surface 15b of the current collector 15. The plurality of bipolar electrodes 11 are laminated such that the positive electrode active material layer 16 of one bipolar electrode 11 faces the negative electrode active material layer 17 of another bipolar electrode 11. One surface 15a of the current collector 15 is a surface facing one direction in the Z direction, and the other surface 15b of the current collector 15 is a surface facing the other direction in the Z direction.

[0017] The positive electrode active material layer 16 and the negative electrode active material layer 17 have a rectangular shape when viewed from the Z direction. The negative electrode active material layer 17 is slightly larger than the positive electrode active material layer 16 when viewed from the Z direction. That is, in a plan view when viewed from the Z direction, the entire formation region of the positive electrode active material layer 16 is located within the formation region of the negative electrode active material layer 17.

[0018] The negative terminal electrode 12 includes a current collector 15 and a negative electrode active material layer 17 provided on the other surface 15b of the current collector 15. On one surface 15a of the current collector 15 included in the negative terminal electrode 12, neither the positive electrode active material layer 16 nor the negative electrode active material layer 17 is provided. That is, no active material layer is provided on one surface 15a of the current collector 15 included in the negative terminal electrode 12. The negative terminal electrode 12 is disposed at one end of the laminate 10 in the Z direction such that the other surface 15b faces the inside in the Z direction. The negative terminal electrode 12 is laminated on the bipolar electrode 11 such that its negative electrode active material layer 17 faces the positive electrode active material layer 16 of the bipolar electrode 11. Therefore, one surface 15a of the current collector 15 included in the negative terminal electrode 12 faces the outside of the laminate 10 and is an exposed surface at least partially exposed to the outside of the laminate 10. In the present embodiment, one surface 15a of the current collector 15 included in the negative terminal electrode 12 is an exposed surface entirely exposed to the outside of the laminate 10.

[0019] The positive terminal electrode 13 includes a current collector 15 and a positive electrode active material layer 16 provided on one surface 15a of the current collector 15. On the other surface 15b of the current collector 15 included in the positive terminal electrode 13, neither the positive electrode active material layer 16 nor the negative electrode active material layer 17 is provided. That is, no active material layer is provided on the other surface 15b of the current collector 15 included in the positive terminal electrode 13. The positive terminal electrode 13 is disposed at the other end of the laminate 10 in the Z direction such that one surface 15a faces the inside in the Z direction. The positive terminal electrode 13 is laminated on the bipolar electrode 11 such that its positive electrode active material layer 16 faces the negative electrode active material layer 17 of the bipolar electrode 11. Therefore, the other surface 15b of the current collector 15 included in the positive terminal electrode 13 faces the outside of the laminate 10 and is an exposed surface at least partially exposed to the outside of the laminate 10. In the present embodiment, the other surface 15b of the current collector 15 included in the positive terminal electrode 13 is an exposed surface entirely exposed to the outside of the laminate 10.

[0020] As described above, the laminate 10 includes a plurality of electrodes laminated along the Z direction, which is the lamination direction. The plurality of electrodes each include a current collector 15 having one surface 15a and the other surface 15b facing each other in the Z direction, and the one surface 15a faces the same direction along the Z direction. The plurality of electrodes also include a positive terminal electrode 13 including a positive electrode active material layer 16 provided on one surface 15a of the current collector 15, a negative terminal electrode 12 including a negative electrode active material layer 17 provided on the other surface 15b of the current collector 15 so as to face the positive electrode active material layer 16, and at least one bipolar electrode 11 disposed between the positive terminal electrode 13 and the negative terminal electrode 12.

[0021] The separator 14 is disposed between adjacent electrodes. That is, the separator 14 is disposed between adjacent bipolar electrodes 11, between the negative terminal electrode 12 and the bipolar electrode 11, and between the positive terminal electrode 13 and the bipolar electrode 11. The separator 14 is interposed between the positive electrode active material layer 16 and the negative electrode active material layer 17. The separator 14 separates the positive electrode active material layer 16 and the negative electrode active material layer 17 to prevent short - circuit due to contact of adjacent electrodes while allowing charge carriers such as lithium ions to pass through.

[0022] The current collector 15 is a chemically inert electrical conductor for continuously passing current through the positive electrode active material layer 16 and the negative electrode active material layer 17 during discharge or charge of the lithium - ion secondary battery. The material of the current collector 15 is, for example, a metal material, a conductive resin material, or a conductive inorganic material, etc. Examples of the conductive resin material include a conductive polymer material or a resin obtained by adding a conductive filler to a non - conductive polymer material as needed. The current collector 15 may include a plurality of layers. In this case, each layer of the current collector 15 may include the above - mentioned metal material or conductive resin material.

[0023] A coating layer may be formed on the surface of the current collector 15. The coating layer may be formed by a known method such as plating or spray coating. The current collector 15 may have, for example, a plate shape, a foil shape (e.g., a metal foil), a film shape, or a mesh shape. Examples of the metal foil include aluminum foil, copper foil, nickel foil, titanium foil, or stainless steel foil. Examples of the stainless steel foil include SUS304, SUS316, or SUS301 defined in JIS G4305:2015. By using a stainless steel foil as the current collector 15, the mechanical strength of the current collector 15 can be ensured. The current collector 15 may be an alloy foil or a clad foil of the above metals. When the current collector 15 has a foil shape, the thickness of the current collector 15 may be, for example, 1 μm to 100 μm.

[0024] The positive electrode active material layer 16 contains a positive electrode active material capable of occluding and releasing charge carriers such as lithium ions. Examples of the positive electrode active material include lithium composite metal oxides having a layered rock salt structure, metal oxides having a spinel structure, and polyanion-based compounds. The positive electrode active material may be any material that can be used in a lithium ion secondary battery. The positive electrode active material layer 16 may contain a plurality of positive electrode active materials. In the present embodiment, the positive electrode active material layer 16 contains olivine-type lithium iron phosphate (LiFePO4) as a composite oxide.

[0025] The negative electrode active material layer 17 contains a negative electrode active material capable of occluding and releasing charge carriers such as lithium ions. The negative electrode active material may be any of a single substance, an alloy, or a compound. Examples of the negative electrode active material include Li, carbon, and metal compounds. The negative electrode active material may be an element capable of alloying with lithium or its compound. Examples of the carbon include natural graphite, artificial graphite, hard carbon (carbon with low graphitization property), or soft carbon (carbon with high graphitization property). Examples of the artificial graphite include highly oriented graphite and mesocarbon microbeads. Examples of the element capable of alloying with lithium include silicon or tin. In the present embodiment, the negative electrode active material layer 17 contains graphite as a carbon-based material.

[0026] Each of the positive electrode active material layer 16 and the negative electrode active material layer 17 may further contain a conductive assistant, a binder, an electrolyte, an electrolyte supporting salt for enhancing ionic conductivity, etc., as necessary. The conductive assistant is added to enhance the conductivity of each electrode (bipolar electrode 11, negative electrode terminal electrode 12, positive electrode terminal electrode 13). The conductive assistant is, for example, acetylene black, carbon black, graphite, or the like.

[0027] Examples of the binder include fluorine-containing resins such as polyvinylidene fluoride, polytetrafluoroethylene, and fluororubber, thermoplastic resins such as polypropylene and polyethylene, imide resins such as polyimide and polyamideimide, alkoxysilyl group-containing resins, acrylic resins such as acrylic acid or methacrylic acid, styrene-butadiene rubber (SBR), carboxymethyl cellulose, alginates such as sodium alginate and ammonium alginate, water-soluble cellulose ester crosslinked products, starch-acrylic acid graft polymers, and the like. These binders can be used alone or in combination. As the solvent, for example, water, N-methyl-2-pyrrolidone (NMP), or the like is used. Examples of the electrolyte include a polymer matrix, an ion-conductive polymer, an electrolytic solution, and the like. Examples of the electrolyte supporting salt include lithium salts and the like.

[0028] The separator 14 may be, for example, a porous sheet or nonwoven fabric containing a polymer that absorbs and retains an electrolyte. Examples of the material of the separator 14 include polypropylene, polyethylene, polyolefin, polyester, and the like. The separator 14 may have a single-layer structure or a multilayer structure. The multilayer structure may have, for example, an adhesive layer or a ceramic layer as a heat-resistant layer. The separator 14 may be impregnated with an electrolyte. The separator 14 may be composed of an electrolyte such as a polymer electrolyte or an inorganic-type electrolyte. Examples of the electrolyte impregnated in the separator 14 include a liquid electrolyte (electrolytic solution) containing a non-aqueous solvent and an electrolyte salt dissolved in the non-aqueous solvent, or a polymer gel electrolyte containing an electrolyte held in a polymer matrix.

[0029] When the separator 14 is impregnated with the electrolytic solution, as the electrolyte salt, known lithium salts such as LiClO4, LiAsF6, LiPF6, LiBF4, LiCF3SO3, LiN(FSO2)2, LiN(CF3SO2)2, etc. may be used. As the non-aqueous solvent, known solvents such as cyclic carbonates, cyclic esters, chain carbonates, chain esters, ethers, etc. may be used. Note that two or more of these known solvent materials may be used in combination.

[0030] The sealing portion 20 is formed in a frame shape at the peripheral edge portion of the laminate 10 so as to surround the laminate 10. The sealing portion 20 can be joined to each of one surface 15a and the other surface 15b of each current collector 15 at the peripheral edge portion 15c of each current collector 15. The sealing portion 20 seals each of the spaces S between the current collectors 15 adjacent in the Z direction. An electrolyte is accommodated in each space S. That is, the sealing portion 20 defines the space S that accommodates the electrolyte together with the current collectors 15 adjacent in the Z direction. When the electrolyte is liquid, the sealing portion 20 prevents the electrolyte from permeating to the outside.

[0031] The sealing portion 20 suppresses the intrusion of moisture and the like from the outside of the laminate 10 into the space S. The sealing portion 20 prevents, for example, the gas generated at each electrode due to charge and discharge reactions and the like from leaking to the outside of the power storage module 1. The sealing portion 20 contains an insulating material. Examples of the material of the sealing portion 20 include various resin materials such as polypropylene, polyethylene, polystyrene, ABS resin, acid-modified polypropylene, acid-modified polyethylene, acrylonitrile styrene resin, etc.

[0032] As shown in FIGS. 1 and 2, the exterior body 30 is formed by a first sheet member 31 and a second sheet member 32 that are joined to each other so as to wrap the laminate 10. The exterior body 30 is arranged so as to be in close contact with the laminate 10. The exterior body 30 houses and seals the laminate 10 inside. Since the inside of the exterior body 30 is sealed, it suppresses the intrusion of moisture and the like from the outside of the exterior body 30 to the inside.

[0033] Each of the first sheet member 31 and the second sheet member 32 is a sheet member having a rectangular shape when viewed from the Z direction. Each of the first sheet member 31 and the second sheet member 32 may be pre-formed into a predetermined shape so as to form a bag shape when overlapped with each other, or may be formed into a bag shape by sandwiching and joining the laminate 10 therebetween.

[0034] Each of the first sheet member 31 and the second sheet member 32 has a first insulating layer 41, a second insulating layer 42, and a metal layer 43. The first insulating layer 41 is laminated on one surface 43a of the metal layer 43 on the laminate 10 side. The second insulating layer 42 is laminated on the other surface 43b of the metal layer 43 opposite to the one surface 43a where the first insulating layer 41 is provided. That is, the metal layer 43 is disposed between the first insulating layer 41 and the second insulating layer 42. In the present embodiment, the first insulating layer 41 is in contact with the outer surface 20a of the sealing portion 20, one surface 15a of the peripheral portion 15c of the current collector 15 included in the negative terminal electrode 12, and the other surface 15b of the peripheral portion 15c of the current collector 15 included in the positive terminal electrode 13. The first insulating layer 41 and the second insulating layer 42 may have a single-layer structure or a multilayer structure. In the case of a multilayer structure, the first insulating layer 41 and the second insulating layer 42 may have, for example, an adhesive layer or the like.

[0035] The first sheet member 31 has a first peeling portion 44 from which the first insulating layer 41 and the second insulating layer 42 are peeled off from the metal layer 43. That is, the first peeling portion 44 is a portion where the metal layer 43 of the first sheet member 31 is exposed. And the first peeling portion 44 of the first sheet member 31 is arranged so as to face the negative terminal electrode 12. The first peeling portion 44 has one surface 43a on the laminate 10 side in contact with one surface 15a of the non-peripheral portion 15d of the current collector 15 included in the negative terminal electrode 12. The other surface 43b of the first peeling portion 44 opposite to the one surface 43a on the laminate 10 side is exposed to the outside of the exterior body 30.

[0036] The second sheet member 32 has a second peeling portion 45 where the first insulating layer 41 and the second insulating layer 42 are peeled off from the metal layer 43. That is, the second peeling portion 45 is a portion where the metal layer 43 of the second sheet member 32 is exposed. And the second peeling portion 45 of the second sheet member 32 is arranged to face the positive terminal electrode 13. On the second peeling portion 45, one surface 43a on the laminated body 10 side is in contact with the other surface 15b of the current collector 15 included in the positive terminal electrode 13 at a non-peripheral portion 15d. On the second peeling portion 45, the other surface 43b on the side opposite to the one surface 43a on the laminated body 10 side is exposed to the outside of the exterior body 30.

[0037] In this way, the first peeling portion 44 is electrically connected to the negative terminal electrode 12 by contacting the current collector 15 included in the negative terminal electrode 12. The second peeling portion 45 is electrically connected to the positive terminal electrode 13 by contacting the current collector 15 included in the positive terminal electrode 13. The first peeling portion 44 and the second peeling portion 45 have a function of electrically connecting a plurality of power storage modules 1.

[0038] The first insulating layer 41 is made of an insulating resin. The material of the first insulating layer 41 is, for example, polypropylene (PP), polyethylene (PE), polyamide (PA), nylon (NY), etc. The material of the first insulating layer 41 can be selected from the same kind of materials as the sealing portion 20 from the viewpoint of adhesiveness with the sealing portion 20. The second insulating layer 42 is made of, for example, an insulating resin. The material of the second insulating layer 42 is, for example, polypropylene (PP), polyethylene terephthalate (PET), nylon (NY), etc. The metal layer 43 is made of a conductive metal. The material of the metal layer 43 is aluminum (Al), aluminum alloy, stainless steel, copper (Cu), copper alloy, iron (Fe), etc. The material of the metal layer 43 can be selected as a material with low water permeability (small water permeability coefficient), such as aluminum or stainless steel.

[0039] Each of the first sheet member 31 and the second sheet member 32 is a laminate sheet such as an aluminum laminate sheet, a stainless steel laminate sheet, a copper laminate sheet, an iron laminate sheet, or the like. As a specific example of the aluminum laminate sheet, a laminate sheet having a three-layer structure (PE / Al / PET) including a first insulating layer 41 of PE, a metal layer 43 of Al, and a second insulating layer 42 of PET can be mentioned. As another specific example of the aluminum laminate sheet, a laminate sheet having a three-layer structure (PE / Al / NY) including a first insulating layer 41 of PE, a metal layer 43 of Al, and a second insulating layer 42 of NY can be mentioned.

[0040] Each of the first insulating layer 41, the second insulating layer 42, and the metal layer 43 may have a single-layer structure or a multilayer structure. Therefore, each of the first sheet member 31 and the second sheet member 32 may have a structure of three or more layers. For example, it may be a laminate sheet having a four-layer structure composed of CPP / NY / Al / PET or the like.

[0041] Thus, the exterior body 30 is formed by a pair of sheet members joined to each other so as to wrap the laminate 10, and seals the laminate 10 inside. Each of the pair of sheet members has a first insulating layer 41 and a second insulating layer 42 which are a pair of insulating layers, a metal layer 43 disposed between the first insulating layer 41 and the second insulating layer 42, and a peeling portion where a part of each of the first insulating layer 41 and the second insulating layer 42 is peeled off from the metal layer 43. And the first peeling portion 44 which is the peeling portion of the first sheet member 31 which is one of the pair of sheet members is arranged so as to face the negative terminal electrode 12, and the second peeling portion 45 which is the peeling portion of the second sheet member 32 which is the other of the pair of sheet members is arranged so as to face the positive terminal electrode 13.

[0042] The interior of the exterior body 30 may be depressurized. Since the interior of the exterior body 30 is depressurized, surface pressure is applied to the laminate 10 accommodated inside the exterior body 30, so that unevenness in current density in the power storage module 1 is suppressed.

[0043] The exterior body 30 may have a first adhesive layer 51 and a second adhesive layer 52. Each of the first adhesive layer 51 and the second adhesive layer 52 has conductivity. Each of the first adhesive layer 51 and the second adhesive layer 52 can be formed by applying a conductive adhesive such as a conductive epoxy adhesive or a conductive silicone adhesive to one surface 43a of the first peeling portion 44 and one surface 43a of the second peeling portion 45.

[0044] The first adhesive layer 51 is disposed between the first peeling portion 44 and the current collector 15 included in the negative terminal electrode 12. The first adhesive layer 51 adheres the first peeling portion 44 to the current collector 15 included in the negative terminal electrode 12. The second adhesive layer 52 is disposed between the second peeling portion 45 and the current collector 15 included in the positive terminal electrode 13. The second adhesive layer 52 adheres the second peeling portion 45 to the current collector 15 included in the positive terminal electrode 13.

[0045] By providing the first adhesive layer 51 and the second adhesive layer 52 on the exterior body 30, conduction between the first peeling portion 44 and the current collector 15 included in the negative terminal electrode 12 and conduction between the second peeling portion 45 and the current collector 15 included in the positive terminal electrode 13 can be surely ensured. As a result, an increase in resistance in the power storage module 1 is suppressed. Further, by providing the first adhesive layer 51 and the second adhesive layer 52 on the exterior body 30, displacement of the laminate 10 inside the exterior body 30 that may occur when an external force is applied to the power storage module 1 is suppressed.

[0046] Next, with reference to FIG. 3, a method for manufacturing the power storage module 1 according to Embodiment 1 will be described. FIG. 3 is a flowchart showing a method for manufacturing the power storage module according to Embodiment 1. As shown in FIG. 3, the method for manufacturing the power storage module 1 has a laminate manufacturing step (step S1) of manufacturing the laminate 10 and a laminate sealing step (step S2) of sealing the laminate 10 inside the exterior body 30.

[0047] In the laminate manufacturing process, first, as a plurality of electrodes, a plurality of bipolar electrodes 11, a positive terminal electrode 13, and a negative terminal electrode 12 are prepared, and a plurality of separators 14 are prepared. Then, in the laminate manufacturing process, the laminate 10 is obtained by laminating the plurality of electrodes along the Z direction with the separator 14 interposed therebetween. At this time, the plurality of electrodes are laminated such that one surface 15a of each current collector 15 faces the same direction along the Z direction, and a plurality of bipolar electrodes 11 are arranged between the positive terminal electrode 13 and the negative terminal electrode 12. Further, a sealing portion 20 may be formed at the peripheral portion of the laminate 10. The sealing portion 20 can be formed, for example, by injection molding a resin material which is the material of the sealing portion 20. The electrolyte can be injected into each space S, for example, from an injection port provided in the sealing portion 20.

[0048] Next, the laminate sealing process includes, for example, a peeling process (S2-1), an arranging process (S2-2), and a bonding process (S2-3). In the peeling process, peeling portions (a first peeling portion 44 and a second peeling portion 45) in which a part of each of the first insulating layer 41 and the second insulating layer 42 is peeled from the metal layer 43 are formed. By the peeling process, the first sheet member 31 and the second sheet member 32 can be obtained. The first peeling portion 44 and the second peeling portion 45 can be formed, for example, by irradiating the first sheet member 31 and the second sheet member 32 before forming the first peeling portion 44 and the second peeling portion 45 with laser light to peel the first insulating layer 41 and the second insulating layer 42 of the irradiated portion of the laser light from the metal layer 43.

[0049] The type of laser can be appropriately selected according to the materials of the first insulating layer 41 and the second insulating layer 42. Examples of the type of laser include YAG laser, fiber laser, semiconductor laser, carbon dioxide laser, helium-neon laser, excimer laser, argon laser, etc. By using such laser processing, the first insulating layer 41 and the second insulating layer 42 can be peeled off at high speed, so that the first peeling portion 44 and the second peeling portion 45 can be formed in a short time. The method of forming the first peeling portion 44 and the second peeling portion 45 is not limited to the method using laser processing. The method of forming the first peeling portion 44 and the second peeling portion 45 may be, for example, a method of dissolving a part of each of the first insulating layer 41 and the second insulating layer 42 with an appropriate solvent and peeling it from the metal layer 43, or a method using cutting processing such as milling processing in which a part of each of the first insulating layer 41 and the second insulating layer 42 is cut and peeled from the metal layer 43.

[0050] Next, in the arranging step, the first sheet member 31 and the second sheet member 32 are arranged such that the first peeling portion 44 faces the negative terminal electrode 12 included in the laminate 10 and the second peeling portion 45 faces the positive terminal electrode 13 included in the laminate 10. Also, in the arranging step, the laminate 10 is sandwiched between them and the first sheet member 31 and the second sheet member 32 are overlapped.

[0051] Next, in the joining step, the contact surfaces of the peripheral edges 31a and 32a of the first sheet member 31 and the second sheet member 32 overlapped in the arranged state as described above are joined. By the joining step, a joined portion is formed. When the joined portion is formed, the inside of the exterior body 30 is sealed. The method of joining the first sheet member 31 and the second sheet member 32 is not particularly limited, and examples include a method of welding the first insulating layers 41 together and adhesion using an adhesive. Examples of the method of welding the first insulating layers 41 together include a hot plate welding method, an ultrasonic welding method, a vibration welding method, or a laser welding method. Also, the laminate sealing step may include a pressure reducing step before the joining step. In the pressure reducing step, the inside of the exterior body 30 is depressurized using a vacuum pump or the like.

[0052] As described above, the manufacturing method of the power storage module 1 according to the present embodiment includes a laminate manufacturing step of manufacturing a laminate 10 including a plurality of electrodes laminated along the Z direction, which is the stacking direction, and a laminate sealing step of sealing the laminate 10 inside an exterior body 30 formed by a pair of sheet members joined to each other so as to wrap the laminate 10. The plurality of electrodes each include a current collector 15 having one surface 15a and the other surface 15b facing each other in the Z direction, and one surface 15a facing the same direction along the Z direction. Further, the plurality of electrodes include a positive electrode terminal electrode 13 including a positive electrode active material layer 16 provided on one surface 15a of the current collector 15, a negative electrode terminal electrode 12 including a negative electrode active material layer 17 provided on the other surface 15b of the current collector 15 so as to face the positive electrode active material layer 16, and at least one bipolar electrode 11 disposed between the positive electrode terminal electrode 13 and the negative electrode terminal electrode 12. Each of the pair of sheet members has a first insulating layer 41 and a second insulating layer 42 which are a pair of insulating layers, a metal layer 43 disposed between the first insulating layer 41 and the second insulating layer 42, and a peeling portion in which a part of each of the first insulating layer 41 and the second insulating layer 42 is peeled off from the metal layer 43. The first peeling portion 44, which is the peeling portion of the first sheet member 31, which is one of the pair of sheet members, is disposed so as to face the negative electrode terminal electrode 12, and the second peeling portion 45, which is the peeling portion of the second sheet member 32, which is the other of the pair of sheet members, is disposed so as to face the positive electrode terminal electrode 13.

[0053] According to such a manufacturing method, the power storage module 1 shown in FIGS. 1 and 2 can be manufactured.

[0054] Note that the present disclosure is not limited to the above-described embodiment, and can be appropriately changed without departing from the gist. For example, in the above-described embodiment, the exterior body 30 formed by the first sheet member 31 and the second sheet member 32 in which the joint surfaces of the peripheral portions 31a and 32a are joined in a state where the peripheral portions 31a and 32a of the first sheet member 31 and the second sheet member 32 substantially coincide with each other is taken as an example, but the configuration of the exterior body 30 is not limited to this.

[0055] Therefore, FIG. 4 is a perspective view and a partially enlarged cross-sectional view of a power storage module according to a modified example. The perspective view of FIG. 4 corresponds to FIG. 2. The power storage module 100 shown in FIG. 4 has the same configuration as the power storage module 1 except that it has an outer package 300 instead of the outer package 30.

[0056] The outer package 300 of the power storage module 100 is formed by the first sheet member 31 and the second sheet member 32 in which the contact surfaces of the peripheral edges 31a and 32a are joined in a state where the peripheral edges 31a and 32a of the first sheet member 31 and the second sheet member 32 are arranged so as to be displaced from each other. The power storage module 100 having such an outer package 300 is suitable when using the first sheet member 31 and the second sheet member 32 in which the metal layer 43 is exposed on each end face.

[0057] The broken line in FIG. 4 shows an enlarged cross-sectional view of the joint portion of the outer package 300. The outer package 300 is obtained by joining the contact surfaces of the peripheral edges 31a and 32a of the first sheet member 31 and the second sheet member 32 that are overlapped with the peripheral edge 31a being arranged 1 mm or more outside the peripheral edge 32a. The outer package 300 thus obtained has a protruding portion 301 where the first sheet member 31 protrudes outside the second sheet member 32. That is, the protruding amount L of the protruding portion is 1 mm or more. The protruding amount L is the distance between the end face of the first sheet member 31 and the end face of the second sheet member 32.

[0058] In the power storage module 100 in which the laminate 10 is sealed inside the outer package 300 configured as described above, the creepage distance between the metal layer 43 of the first sheet member 31 and the metal layer 43 of the second sheet member 32 is ensured. Therefore, a short circuit between the first sheet member 31 and the second sheet member 32 that may occur when the metal layer 43 is exposed on each end face of the first sheet member 31 and the second sheet member 32 is suppressed.

Explanation of reference numerals

[0059] 1, 100 Power storage module 10 Laminate 11 Bipolar electrode 12 Negative terminal electrode 13 Positive terminal electrode 14 Separator 15 Current collector 15a One side 15b The other side 15c Peripheral part 15d Non-peripheral part 16 Positive electrode active material layer 17 Negative electrode active material layer 20 Sealing part 20a Outer surface 30, 300 Exterior body 31 First sheet member 31a Peripheral part 32 Second sheet member 32a Peripheral part 41 First insulating layer 42 Second insulating layer 43 Metal layer 43a One side 43b The other side 44 First peeling part 45 Second peeling part 51 First adhesive layer 52 Second adhesive layer L Protrusion amount S Space

Claims

1. A laminate including a plurality of electrodes laminated along a stacking direction, and An exterior body formed by a pair of sheet members joined to each other so as to wrap the laminate, and sealing the laminate inside, The plurality of electrodes Each include a current collector having one surface and the other surface facing each other in the stacking direction and the one surface facing the same direction along the stacking direction, A positive terminal electrode including a positive electrode active material layer provided on the one surface of the current collector, A negative terminal electrode including a negative electrode active material layer provided on the other surface of the current collector so as to face the positive electrode active material layer, At least one bipolar electrode disposed between the positive terminal electrode and the negative terminal electrode, Each of the pair of sheet members A pair of insulating layers, A metal layer disposed between the pair of insulating layers, A peeling portion in which a part of each of the pair of insulating layers is peeled off from the metal layer, A power storage module in which one of the peeling portions of the pair of sheet members is disposed so as to face the negative terminal electrode, and the other of the peeling portions of the pair of sheet members is disposed so as to face the positive terminal electrode.

2. The exterior body has a protruding portion in which one of the pair of sheet members protrudes outside the other of the pair of sheet members, The power storage module according to claim 1, wherein a protruding amount of the protruding portion is 1 mm or more.

3. The power storage module according to claim 1, wherein the inside of the exterior body is depressurized.

4. The exterior body has a pair of conductive adhesive layers, One of the pair of adhesive layers adheres the peeling portion facing the positive terminal electrode to the current collector included in the positive terminal electrode, The power storage module according to claim 1, wherein the other of the pair of adhesive layers adheres the peeling portion facing the negative terminal electrode to the current collector included in the negative terminal electrode.

5. A laminate manufacturing step of manufacturing a laminate including a plurality of electrodes laminated along a stacking direction, and A laminate sealing step of sealing the laminate inside an exterior body formed by a pair of sheet members joined to each other so as to wrap the laminate, The plurality of electrodes Each include a current collector having one surface and the other surface facing each other in the stacking direction and the one surface facing the same direction along the stacking direction, A positive terminal electrode including a positive electrode active material layer provided on the one surface of the current collector, A negative electrode terminal electrode including a negative electrode active material layer provided on the other surface of the current collector so as to face the positive electrode active material layer; At least one bipolar electrode disposed between the positive electrode terminal electrode and the negative electrode terminal electrode; and Each of the pair of sheet members includes A pair of insulating layers; A metal layer disposed between the pair of insulating layers; and A peeling portion in which a part of each of the pair of insulating layers is peeled off from the metal layer; and A method for manufacturing a power storage module, wherein one of the peeling portions of the pair of sheet members is disposed so as to face the negative electrode terminal electrode, and the other peeling portion of the pair of sheet members is disposed so as to face the positive electrode terminal electrode.

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