Power storage module and method for manufacturing power storage module

Abstract

The invention provides a power storage module and a method for manufacturing the power storage module. The power storage module has a laminated body including a plurality of laminated electrodes, and an exterior body formed of a pair of sheet members joined to each other and enclosing the laminated body therein. The plurality of electrodes includes a positive electrode terminal electrode including a positive electrode active material layer, a negative electrode terminal electrode including a negative electrode active material layer, and a bipolar electrode disposed between the positive electrode terminal electrode and the negative electrode terminal electrode. Each of the pair of sheet members has a peeling portion obtained by peeling a portion of each of the pair of insulating layers from a metal layer disposed between the pair of insulating layers, and one of the peeling portions of the pair of sheet members is disposed so as to face the negative terminal electrode. The peeling portion of the other of the pair of sheet members is disposed so as to face the positive terminal electrode.

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] It is known that sometimes, in a non-aqueous secondary battery in which the electrolyte is composed of a non-aqueous electrolyte, the battery performance deteriorates due to the intrusion of moisture into the battery interior. Specifically, if moisture intrudes into the battery interior, there is a possibility that the electrolyte deteriorates and the resistance increases, and the active material and the film decompose due to 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 body in order to suppress the intrusion of moisture such as humidity in the atmosphere. As an example of a non-aqueous secondary battery, a power storage module having a laminate including bipolar electrodes and terminal electrodes of positive and negative electrodes is disclosed in Japanese Unexamined Patent Application Publication No. 2023-110291.

[0003] The power storage module described in Japanese Unexamined Patent Application Publication No. 2023-110291 includes: a laminate having an outer side surface; and a sheet member disposed in close contact with the laminate so as to cover the outer side 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. The plurality of current collectors have: a plurality of electrodes stacked in such a manner that one surface faces the same direction along the stacking direction; and a sealing portion that divides a space for accommodating an electrolyte together with the current collectors adjacent in the stacking direction. The electrodes include bipolar electrodes, a positive electrode terminal electrode, and a negative electrode terminal electrode. The bipolar electrode has 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. The positive electrode terminal electrode has 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. The negative electrode terminal electrode has 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 has a plurality of first resin layers, a plurality of separators, and a second resin layer. The plurality of first resin layers are in a frame shape provided at the peripheral portions of the respective current collectors among the plurality of current collectors. The plurality of separators are in a frame shape arranged so as to be interposed between the first resin layers adjacent in the stacking direction. The second resin layer is formed by fusing the ends of the plurality of first resin layers and the plurality of separators, which are on the side opposite to the space when viewed from the stacking direction, to each other. The outer side surface includes a first surface, a second surface, and a third surface. The first surface is the surface of the first resin layer provided on the other surface of the current collector of the positive electrode terminal electrode, which is on the side opposite to the other surface of the current collector. The second surface is the surface of the first resin layer provided on one surface of the current collector of the negative electrode terminal electrode, which is on the side opposite to one surface of the current collector. The third surface is the surface of the second resin layer on the side opposite to the space, 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 side surface side of the metal layer. The sheet member 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 at positions outside the inner edges of the first resin layer and the separator and inside the outer edges of the current collector when viewed from the stacking direction. The first insulating member is provided so as to cover the first end portion from the first surface over the sheet member and is bonded to the first surface and the sheet member. The second insulating member is provided so as to cover the second end portion from the second surface over the sheet member and is bonded to the second surface and the sheet member.

[0004] Japanese Unexamined Patent Application Publication No. 2023-110291 discloses that: since the sheet member including a metal layer is provided so as to cover the outer side surface of the laminate in this power storage module, moisture intrusion into the laminate can be suppressed as compared with the case where only a resin layer sheet is provided. Summary of the Invention

[0005] Sometimes, in a power storage device having a power storage module, a plurality of power storage modules are stacked with a conductive member therebetween. In this case, adjacent power storage modules are electrically connected to each other via the conductive member.

[0006] Therefore, for example, if the entire surface of the stacked body is encapsulated with a sheet member including a resin layer, conduction between the stacked body and the conductive member cannot be ensured. In order to ensure conduction between the stacked body and the conductive member, as in the technique described in Japanese Unexamined Patent Application Publication No. 2023-110291, at least a part of the terminal electrodes of the positive and negative electrodes included in the stacked body encapsulated with the sheet member is exposed to the outside of the sheet member. However, in such a configuration, moisture easily enters 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, in the power storage module described in Japanese Unexamined Patent Application Publication No. 2023-110291, although short circuits can be suppressed by using a sheet member including a metal layer, there is a problem that moisture ingress cannot be sufficiently suppressed.

[0007] 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 that can suppress short circuits and appropriately suppress moisture ingress.

[0008] A power storage module according to one embodiment includes:

[0009] a stacked body including a plurality of electrodes stacked along a stacking direction; and

[0010] an exterior body formed of a pair of sheet members joined to each other so as to enclose the stacked body, and encapsulating the stacked body inside,

[0011] 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 faces the same direction along the stacking direction,

[0012] the plurality of electrodes have:

[0013] a positive electrode terminal electrode including a positive electrode active material layer provided on one surface of the current collector;

[0014] 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; and

[0015] at least one bipolar electrode disposed between the positive electrode terminal electrode and the negative electrode terminal electrode,

[0016] each of the pair of sheet members has:

[0017] a pair of insulating layers;

[0018] A metal layer disposed between a pair of insulating layers; and

[0019] A peeling portion that peels off a part of each of the pair of insulating layers from the metal layer,

[0020] The peeling portion of one of the pair of sheet members is disposed to face the negative terminal electrode, and the peeling portion of the other of the pair of sheet members is disposed to face the positive terminal electrode.

[0021] In addition, a method for manufacturing a power storage module according to one embodiment includes:

[0022] A laminate manufacturing step of manufacturing a laminate including a plurality of electrodes laminated along a lamination direction; and

[0023] A laminate encapsulation step of encapsulating the laminate inside an outer package formed by a pair of sheet members joined to each other so as to enclose the laminate,

[0024] Each of the plurality of electrodes includes a current collector having one surface and the other surface facing each other in the lamination direction, and one surface faces the same direction along the lamination direction,

[0025] The plurality of electrodes have:

[0026] A positive terminal electrode including a positive electrode active material layer provided on one surface of the current collector;

[0027] 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

[0028] At least one bipolar electrode disposed between the positive terminal electrode and the negative terminal electrode,

[0029] Each of the pair of sheet members has:

[0030] A pair of insulating layers;

[0031] A metal layer disposed between the pair of insulating layers; and

[0032] A peeling portion that peels off a part of each of the pair of insulating layers from the metal layer,

[0033] The peeling portion of one of the pair of sheet members is disposed to face the negative terminal electrode, and the peeling portion of the other of the pair of sheet members is disposed to face the positive terminal electrode.

[0034] Through the present disclosure, it is possible to provide a power storage module and a method for manufacturing a power storage module that can appropriately suppress the intrusion of moisture while suppressing a short circuit. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Hereinafter, the features, advantages, and technical and industrial significance of exemplary embodiments of the present invention will be described with reference to the accompanying drawings, in which like reference numerals denote like elements, and in which:

[0036] Figure 1 is a schematic cross-sectional view of the power storage module according to Embodiment 1.

[0037] Figure 2 is Figure 1 a perspective view of the power storage module shown.

[0038] Figure 3 is a flowchart showing a manufacturing method of the power storage module according to Embodiment 1.

[0039] Figure 4 are a perspective view and a partially enlarged cross-sectional view of the power storage module according to a modified example. Detailed Description of the Invention

[0040] Embodiment 1

[0041] Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. However, the present disclosure is not limited to the following embodiments. In addition, for clarity of explanation, the following description and drawings are appropriately simplified. Further, in the following description, the same or equivalent elements are denoted by the same reference numerals, and repeated explanations are omitted.

[0042] Refer to Figure 1 and Figure 2 to describe the power storage module 1 according to Embodiment 1. Figure 1 is a schematic cross-sectional view of the power storage module according to Embodiment 1. Figure 2 is Figure 1 a perspective view of the power storage module shown. Figure 1 and Figure 2 The power storage module 1 shown can be used, for example, as a storage battery for various vehicles such as forklifts, hybrid electric vehicles, and battery 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 can be either 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 illustrated.

[0043] The power storage module 1 has a laminate 10 and an exterior body 30. As Figure 1 shown, the laminate 10 includes a plurality of electrodes laminated in the Z direction as the lamination direction. In addition to the plurality of electrodes, the laminate 10 further includes a plurality of separators 14, a sealing portion 20, and an electrolyte (not shown). The plurality of electrodes include a plurality of bipolar electrodes 11, a negative terminal electrode 12, and a positive terminal electrode 13.

[0044] 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 is, for example, in the shape of a rectangular sheet. 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. A plurality of bipolar electrodes 11 are stacked 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 the surface facing "one side in the Z direction", and the other surface 15b of the current collector 15 is the surface facing "the other side in the Z direction".

[0045] The positive electrode active material layer 16 and the negative electrode active material layer 17 are rectangular in shape when viewed from the Z direction. The negative electrode active material layer 17 is larger in a circle than the positive electrode active material layer 16 when viewed from the Z direction. That is, in a plan view obtained by observing 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.

[0046] The negative terminal electrode 12 includes the current collector 15 and the negative electrode active material layer 17 provided on the other surface 15b of the current collector 15. The negative terminal electrode 12 does not have the positive electrode active material layer 16 and the negative electrode active material layer 17 provided on one surface 15a of the current collector 15. 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 arranged at one end in the Z direction of the laminate 10 such that the other surface 15b faces the inside in the Z direction. The negative terminal electrode 12 is stacked 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 at least a part thereof is an exposed surface 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 that is entirely exposed to the outside of the laminate 10.

[0047] 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. The positive terminal electrode 13 does not provide a positive electrode active material layer 16 and a negative electrode active material layer 17 on the other surface 15b of the current collector 15. That is, an active material layer is not provided on the other surface 15b of the current collector 15 included in the positive terminal electrode 13. The positive terminal electrode 13 is arranged at the other end in the Z direction of the laminate 10 with one surface 15a facing 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 at least a part thereof is an exposed surface 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 that is entirely exposed to the outside of the laminate 10.

[0048] As such, the laminate 10 includes a plurality of electrodes laminated along the Z direction as the lamination direction. And each of the plurality of electrodes includes a current collector 15 having one surface 15a and the other surface 15b facing each other in the Z direction, and one surface 15a faces the same direction along the Z direction. In addition, the plurality of electrodes have a positive terminal electrode 13, a negative terminal electrode 12, and at least one bipolar electrode 11 arranged between the positive terminal electrode 13 and the negative terminal electrode 12. The positive terminal electrode 13 includes a positive electrode active material layer 16 provided on one surface 15a of the current collector 15. The negative terminal electrode 12 includes 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.

[0049] The separator 14 is arranged between adjacent electrodes. That is, the separator 14 is arranged 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. By separating the positive electrode active material layer 16 and the negative electrode active material layer 17, the separator 14 prevents short circuits caused by contact between adjacent electrodes and allows charge carriers such as lithium ions to pass through.

[0050] The current collector 15 is a chemically inert conductor that allows current to continuously flow through the positive electrode active material layer 16 and the negative electrode active material layer 17 during discharge or charging of the lithium-ion secondary battery. Examples of the material of the current collector 15 include metal materials, conductive resin materials, or conductive inorganic materials. As the conductive resin material, for example, a conductive polymer material or a resin obtained by adding a conductive filler to a non-conductive polymer material as needed can be cited. The current collector 15 may have multiple layers. In this case, each layer of the current collector 15 may contain the above-mentioned metal material or conductive resin material.

[0051] A coating layer may be formed on the surface of the current collector 15. This coating layer can be formed, for example, by known methods such as plating treatment or spraying. The current collector 15 can be in the form of a plate, foil (such as a metal foil), film, or mesh, etc. As the metal foil, for example, aluminum foil, copper foil, nickel foil, titanium foil, or stainless steel foil can be cited. As the stainless steel foil, for example, SUS304, SUS316, or SUS301 specified by JIS G4305:2015 can be cited. By using the stainless steel foil as the current collector 15, the mechanical strength of the current collector 15 can be ensured. The current collector 15 can also be an alloy foil or composite foil of the above-mentioned metals. When the current collector 15 is in the form of a foil, the thickness of the current collector 15 can be, for example, 1 μm to 100 μm.

[0052] The positive electrode active material layer 16 contains a positive electrode active material that can occlude and release charge carriers such as lithium ions. As the positive electrode active material, for example, a lithium composite metal oxide having a layered rock salt structure, a metal oxide having a spinel structure, a polyanion-based compound, etc. can be cited. The positive electrode active material only needs to be a material that can be used in a lithium-ion secondary battery. The positive electrode active material layer 16 may also contain multiple 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.

[0053] The negative electrode active material layer 17 contains a negative electrode active material that can occlude and release charge carriers such as lithium ions. The negative electrode active material can be any one of a simple substance, an alloy, or a compound. As the negative electrode active material, for example, Li, carbon, metal compounds, etc. can be cited. The negative electrode active material can also be an element or its compound that can be alloyed with lithium. As carbon, for example, natural graphite, artificial graphite, hard carbon (difficult-to-graphitize carbon), or soft carbon (easy-to-graphitize carbon) can be cited. As artificial graphite, for example, highly oriented graphite, mesocarbon microbeads, etc. can be cited. As an element that can be alloyed with lithium, silicon (Si element) or tin can be cited. In the present embodiment, the negative electrode active material layer 17 contains graphite as a carbon-based material.

[0054] The positive electrode active material layer 16 and the negative electrode active material layer 17 may each optionally further contain a conductive aid for improving conductivity, a binder, an electrolyte, a supporting electrolyte salt for improving ion conductivity, etc. The conductive aid is added to improve the conductivity of each electrode (the bipolar electrode 11, the negative electrode terminal electrode 12, and the positive electrode terminal electrode 13). Examples of the conductive aid include acetylene black, carbon black, or graphite.

[0055] Examples of the binder include fluorine-containing resins such as polyvinylidene fluoride, polytetrafluoroethylene, and fluororubber, thermoplastic resins such as polypropylene and polyethylene, imide-based resins such as polyimide and polyamideimide, resins containing alkoxysilyl groups, 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 bodies, starch-acrylic acid graft polymers, etc. These binders can be used alone or in combination. Solvents such as water and N-methyl-2-pyrrolidone (NMP) are used, for example. Examples of the electrolyte include a polymer matrix, an ion-conductive polymer, and an electrolytic solution. Examples of the supporting electrolyte salt include lithium salts.

[0056] The separator 14 can be, for example, a porous sheet or a non-woven fabric containing a polymer that absorbs and retains the electrolyte. Examples of the material of the separator 14 include polypropylene, polyethylene, polyolefin, polyester, etc. The separator 14 can have a single-layer structure or a multi-layer structure. The multi-layer structure can have, for example, a ceramic layer as an adhesive layer or a heat-resistant layer. The electrolyte can be impregnated in the separator 14. The separator 14 can also 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.

[0057] When the electrolytic solution is impregnated in the separator 14, well-known lithium salts such as LiClO4, LiAsF6, LiPF6, LiBF4, LiCF3SO3, LiN(FSO2)2, and LiN(CF3SO2)2 can be used as the electrolyte salt. In addition, well-known solvents such as cyclic carbonates, cyclic esters, chain carbonates, chain esters, and ethers can be used as the non-aqueous solvent. Furthermore, two or more of the above well-known solvent materials can be used in combination.

[0058] The encapsulation part 20 is formed in a frame shape at the peripheral part of the laminate 10 so as to surround the laminate 10. The encapsulation part 20 can be joined to one surface 15a and the other surface 15b of each current collector 15 at the peripheral part 15c of each current collector 15. The encapsulation part 20 seals the spaces S between the current collectors 15 adjacent in the Z direction respectively. An electrolyte is accommodated in each space S. That is, the encapsulation part 20 and the current collectors 15 adjacent in the Z direction together define the space S for accommodating the electrolyte. When the electrolyte is in a liquid state, the encapsulation part 20 prevents the electrolyte from passing to the outside.

[0059] The encapsulation part 20 suppresses the intrusion of moisture and the like from the outside of the laminate 10 into the space S. The encapsulation part 20 prevents, for example, the gas generated at each electrode due to charge-discharge reactions and the like from leaking to the outside of the power storage module 1. The encapsulation part 20 contains an insulating material. As the material of the encapsulation part 20, various resin materials such as polypropylene, polyethylene, polystyrene, ABS resin, acid-modified polypropylene, acid-modified polyethylene, and acrylonitrile styrene resin can be cited, for example.

[0060] As Figure 1 and Figure 2 shown, the exterior body 30 is formed by a first sheet member 31 and a second sheet member 32 joined to each other so as to enclose the laminate 10. The exterior body 30 is arranged in close contact with the laminate 10. The exterior body 30 accommodates the laminate 10 inside and encapsulates it. Since the inside of the exterior body 30 is airtight, the intrusion of moisture and the like from the outside of the exterior body 30 to the inside is suppressed.

[0061] The first sheet member 31 and the second sheet member 32 are each sheet members having a rectangular shape when viewed from the Z direction. The first sheet member 31 and the second sheet member 32 can each be preformed into a predetermined shape so as to form a bag shape when overlapping each other, or can be formed into a bag shape by sandwiching the laminate 10 therebetween and joining them.

[0062] The first sheet member 31 and the second sheet member 32 respectively have 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 side of the laminate 10. The second insulating layer 42 is laminated on the other surface 43b of the metal layer 43, which is on the opposite side to the 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 contacts the outer side surface 20a of the encapsulation portion 20. The first insulating layer 41 contacts one surface 15a of the peripheral portion 15c in the current collector 15 included in the negative terminal electrode 12. The first insulating layer 41 contacts the other surface 15b of the peripheral portion 15c in 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 multi-layer structure. In the case of a multi-layer structure, the first insulating layer 41 and the second insulating layer 42 may have, for example, an adhesive layer or the like.

[0063] 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 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 disposed so as to face the negative terminal electrode 12. In the first peeling portion 44, one surface 43a on the side of the laminate 10 contacts one surface 15a of the non-peripheral portion 15d in the current collector 15 included in the negative terminal electrode 12. In the first peeling portion 44, the other surface 43b, which is on the opposite side to the one surface 43a on the side of the laminate 10, is exposed to the outside of the outer package 30.

[0064] The second sheet member 32 has a second peeling portion 45 from which the first insulating layer 41 and the second insulating layer 42 are peeled off 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 disposed so as to face the positive terminal electrode 13. In the second peeling portion 45, one surface 43a on the side of the laminate 10 contacts the other surface 15b of the non-peripheral portion 15d in the current collector 15 included in the positive terminal electrode 13. In the second peeling portion 45, the other surface 43b, which is on the opposite side to the one surface 43a on the side of the laminate 10, is exposed to the outside of the outer package 30.

[0065] 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 the function of electrically connecting the plurality of power storage modules 1.

[0066] 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. Regarding the material of the first insulating layer 41, from the viewpoint of adhesiveness to the encapsulation part 20, it can be selected from the same materials as the encapsulation part 20. The second insulating layer 42 is made of an insulating resin, for example. 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. Regarding the material of the metal layer 43, for example, materials with low water permeability (small water permeability coefficient) such as aluminum and stainless steel can be selected.

[0067] The first sheet member 31 and the second sheet member 32 are laminated sheets such as aluminum laminated sheet, stainless steel laminated sheet, copper laminated sheet, iron laminated sheet, etc., for example. As a specific example of the aluminum laminated sheet, a laminated sheet with a three-layer structure (PE / Al / PET) having a first insulating layer 41 of PE, a metal layer 43 of Al, and a second insulating layer 42 of PET can be cited. As another specific example of the aluminum laminated sheet, a laminated sheet with a three-layer structure (PE / Al / NY) having a first insulating layer 41 of PE, a metal layer 43 of Al, and a second insulating layer 42 of NY can be cited.

[0068] The first insulating layer 41, the second insulating layer 42, and the metal layer 43 can each have a single-layer structure or a multi-layer structure. Therefore, the first sheet member 31 and the second sheet member 32 only need to have a structure of three layers or more, and for example, they can also be laminated sheets with a four-layer structure formed by CPP / NY / Al / PET, etc.

[0069] In this way, the exterior body 30 is formed by a pair of sheet members joined to each other in a manner of enclosing the laminate 10, and the laminate 10 is encapsulated inside. Each of the pair of sheet members has a first insulating layer 41 and a second insulating layer 42, a metal layer 43, and a peeling part obtained by peeling a part of the first insulating layer 41 and the second insulating layer 42 from the metal layer 43, respectively. The first insulating layer 41 and the second insulating layer 42 are a pair of insulating layers. The metal layer 43 is disposed between the first insulating layer 41 and the second insulating layer 42. And the first peeling part 44, which is the peeling part of the first sheet member 31 as one of the pair of sheet members, is disposed to face the negative terminal electrode 12. The second peeling part 45, which is the peeling part of the second sheet member 32 as the other of the pair of sheet members, is disposed to face the positive terminal electrode 13.

[0070] The exterior body 30 can also have its interior depressurized. By depressurizing the interior of the exterior body 30, surface pressure is applied to the laminate 10 accommodated inside the exterior body 30, thereby suppressing uneven current density in the power storage module 1.

[0071] The exterior body 30 can have a first adhesive layer 51 and a second adhesive layer 52. The first adhesive layer 51 and the second adhesive layer 52 each have conductivity. The first adhesive layer 51 and the second adhesive layer 52 can be formed by coating a conductive adhesive such as a conductive epoxy adhesive or a conductive silicone adhesive on one surface 43a of the first peeling portion 44 and one surface 43a of the second peeling portion 45, respectively.

[0072] 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 bonds 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 bonds the second peeling portion 45 to the current collector 15 included in the positive terminal electrode 13.

[0073] By providing the first adhesive layer 51 and the second adhesive layer 52 in 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 reliably ensured. As a result, an increase in resistance in the power storage module 1 can be suppressed. In addition, by providing the first adhesive layer 51 and the second adhesive layer 52 in the exterior body 30, positional deviation of the laminate 10 inside the exterior body 30 that may occur when an external force is applied to the power storage module 1 can be suppressed.

[0074] Next, with reference to Figure 3 , the manufacturing method of the power storage module 1 according to Embodiment 1 will be described. Figure 3 is a flowchart showing the manufacturing method of the power storage module according to Embodiment 1. As Figure 3 shown, the manufacturing method of the power storage module 1 has a laminate manufacturing process (S1) for manufacturing the laminate 10 and a laminate encapsulation process (S2) for encapsulating the laminate 10 inside the exterior body 30.

[0075] In the process of manufacturing the laminate, first, a plurality of bipolar electrodes 11, a positive terminal electrode 13, and a negative terminal electrode 12 are prepared as a plurality of electrodes, and a plurality of separators 14 are prepared. And, in the process of manufacturing the laminate, 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 in such a manner 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 disposed between the positive terminal electrode 13 and the negative terminal electrode 12. Moreover, an encapsulation portion 20 can be formed at the peripheral portion of the laminate 10. The encapsulation portion 20 can be formed, for example, by injection molding a resin material as the material of the encapsulation portion 20. The electrolyte can be injected into each space S, for example, from an injection port provided in the encapsulation portion 20.

[0076] Next, the laminate encapsulation process includes, for example, a peeling process (S2-1), a placement process (S2-2), and a bonding process (S2-3). In the peeling process, a peeled portion (a first peeled portion 44 and a second peeled portion 45) is formed by peeling a part of the first insulating layer 41 and the second insulating layer 42 from the metal layer 43, respectively. By the peeling process, the first sheet member 31 and the second sheet member 32 can be obtained. For example, the first sheet member 31 and the second sheet member 32 before the formation of the first peeled portion 44 and the second peeled portion 45 are irradiated with laser light. The first insulating layer 41 and the second insulating layer 42 of the irradiated portion are peeled from the metal layer 43. Thereby, the first peeled portion 44 and the second peeled portion 45 can be formed.

[0077] The type of laser can be appropriately selected according to the respective 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. If such laser processing is used, the first insulating layer 41 and the second insulating layer 42 can be peeled at high speed, and thus the first peeled portion 44 and the second peeled portion 45 can be formed in a short time. The method of forming the first peeled portion 44 and the second peeled portion 45 is not limited to the method using laser processing. The method of forming the first peeled portion 44 and the second peeled portion 45 can also be, for example, a method of peeling from the metal layer 43 by dissolving a part of each of the first insulating layer 41 and the second insulating layer 42 with an appropriate solvent. The method of forming the first peeled portion 44 and the second peeled portion 45 can also be a cutting process such as a milling process of cutting a part of each of the first insulating layer 41 and the second insulating layer 42 and peeling from the metal layer 43.

[0078] Next, in the configuration process, 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. Further, in the configuration process, the first sheet member 31 and the second sheet member 32 are overlapped so as to sandwich the laminate 10 therebetween.

[0079] Next, in the joining process, the contact surfaces of the peripheral portions 31a and 32a of the first sheet member 31 and the second sheet member 32 overlapped in the state arranged as described above are joined to each other. A joined portion is formed by the joining process. After the joined portion is formed, the inside of the outer package 30 is sealed. The method of joining the first sheet member 31 and the second sheet member 32 is not particularly limited, and examples thereof include a method of welding the first insulating layers 41 to each other and adhesion using an adhesive. As the method of welding the first insulating layers 41 to each other, a hot plate welding method, an ultrasonic welding method, a vibration welding method, a laser welding method, or the like can be cited. Further, regarding the laminate packaging process, a decompression process may be included before the joining process. In the decompression process, the inside of the outer package 30 is decompressed using a vacuum pump or the like.

[0080] In this way, the manufacturing method of the power storage module 1 according to the present embodiment includes a laminate manufacturing process and a laminate encapsulation process. The laminate manufacturing process manufactures a laminate 10 including a plurality of electrodes laminated along the Z direction as the lamination direction. The laminate encapsulation process encapsulates the laminate 10 inside an exterior body 30 formed by a pair of sheet members joined to each other so as to enclose the laminate 10. Each of the plurality of electrodes includes a current collector 15 having a first surface 15a and a second surface 15b facing each other in the Z direction, and the first surface 15a faces the same direction along the Z direction. Further, the plurality of electrodes include a positive terminal electrode 13, a negative terminal electrode 12, and at least one bipolar electrode 11 disposed between the positive terminal electrode 13 and the negative terminal electrode 12. The positive terminal electrode 13 includes a positive electrode active material layer 16 provided on the first surface 15a of the current collector 15. The negative terminal electrode 12 includes a negative electrode active material layer 17 provided on the second surface 15b of the current collector 15 so as to face the positive electrode active material layer 16. Each of the pair of sheet members has a first insulating layer 41 and a second insulating layer 42, a metal layer 43, and a peeled portion obtained by peeling a part of the first insulating layer 41 and the second insulating layer 42 from the metal layer 43, respectively. The first insulating layer 41 and the second insulating layer 42 are a pair of insulating layers. The metal layer 43 is disposed between the first insulating layer 41 and the second insulating layer 42. And, the first peeled portion 44, which is the peeled portion of the first sheet member 31 as one of the pair of sheet members, is disposed so as to face the negative terminal electrode 12. The second peeled portion 45, which is the peeled portion of the second sheet member 32 as the other of the pair of sheet members, is disposed so as to face the positive terminal electrode 13.

[0081] According to such a manufacturing method, it is possible to manufacture Figure 1 and Figure 2 the power storage module 1 shown.

[0082] In addition, the present disclosure is not limited to the above-described embodiment, and can be appropriately modified without departing from the gist. For example, in the above-described embodiment, an example of the exterior body 30 formed by the first sheet member 31 and the second sheet member 32 is given. Regarding the first sheet member 31 and the second sheet member 32, the joint surfaces of the peripheral portions 31a and 32a are joined in a state where the peripheral portions 31a and 32a are disposed in a substantially coincident manner with each other. The configuration of the exterior body 30 is not limited thereto.

[0083] In view of this, Figure 4 are a perspective view and a partial enlarged cross-sectional view of the power storage module according to the modification example. Figure 4 The perspective view of Figure 2 is equivalent to the view of Figure 4 The power storage module 100 shown has the same configuration as the power storage module 1 except that it has an exterior body 300 instead of the exterior body 30.

[0084] The exterior body 300 of the power storage module 100 is formed by a first sheet member 31 and a second sheet member 32. The first sheet member 31 and the second sheet member 32 join the contact surfaces of the peripheral portions 31a and 32a with each other in a state where the peripheral portions 31a and 32a of the first sheet member 31 and the second sheet member 32 are arranged offset from each other. The power storage module 100 having such an exterior body 300 is preferable when the first sheet member 31 and the second sheet member 32 with the metal layers 43 exposed at the respective end faces are used.

[0085] Figure 4 A cross-sectional view showing an enlarged view of the joint portion of the exterior body 300 is shown within the dashed line. The exterior body 300 is obtained by joining the contact surfaces of the peripheral portions 31a and 32a of the first sheet member 31 and the second sheet member 32 that overlap in a state where the peripheral portion 31a is disposed at a position 1 mm or more outside the peripheral portion 32a. The exterior body 300 obtained in this way has a protruding portion 301 in which the first sheet member 31 protrudes outward more than the second sheet member 32. That is, the protruding amount L of the protruding portion is 1 mm or more. In addition, 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.

[0086] In the power storage module 100 in which the laminate 10 is encapsulated inside the exterior body 300 configured in this way, 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 can be ensured. Therefore, it is possible to suppress a short circuit between the first sheet member 31 and the second sheet member 32 that may occur when the metal layers 43 are exposed at the respective end faces of the first sheet member 31 and the second sheet member 32.

Claims

1. A power storage module, comprising: A stacked body comprising a plurality of electrodes stacked along a stacking direction; and The outer casing is formed of a pair of sheet members joined to each other so as to enclose the laminated body, and seals the laminated body inside. The plurality of electrodes each include a current collector, the current collector having one surface and another surface facing each other in the stacking direction, and the one surface faces the same direction along the stacking direction, The plurality of electrodes have: A positive terminal electrode, comprising a positive active material layer disposed on the one side of the current collector; a negative terminal electrode including a negative active material layer disposed on the other surface of the current collector in a manner opposing the positive active material layer; and At least one bipolar electrode is disposed between the positive terminal electrode and the negative terminal electrode, The pair of sheet members respectively include: A pair of insulating layers; a metal layer disposed between the pair of insulating layers; and a peeling portion obtained by peeling a part of each of the pair of insulating layers from the metal layer; The release portion of one of the pair of sheet members is disposed so as to face the negative terminal electrode, and the release portion of the other of the pair of sheet members is disposed so as to face the positive terminal electrode.

2. The power storage module according to claim 1, The outer casing has a protrusion in which one of the pair of sheet members protrudes outward from the other of the pair of sheet members. The protrusion amount of the protrusion is 1 mm or more.

3. The power storage module according to claim 1, The interior of the outer casing is decompressed.

4. The power storage module according to claim 1, The outer casing has a pair of adhesive layers, and the pair of adhesive layers are conductive. One of the pair of adhesive layers bonds the release portion facing the positive terminal electrode to the current collector included in the positive terminal electrode. The other of the pair of adhesive layers bonds the release portion facing the negative terminal electrode to the current collector included in the negative terminal electrode.

5. A method for manufacturing a power storage module, comprising: a stacking body manufacturing step of manufacturing a stacking body including a plurality of electrodes stacked along a stacking direction; and a laminate packaging step of packaging the laminate in an outer casing formed of a pair of sheet members joined to each other so as to enclose the laminate, The plurality of electrodes each include a current collector, the current collector having one surface and another surface facing each other in the stacking direction, and the one surface faces the same direction along the stacking direction, The plurality of electrodes have: A positive terminal electrode, comprising a positive active material layer disposed on the one side of the current collector; a negative terminal electrode including a negative active material layer disposed on the other surface of the current collector in a manner opposing the positive active material layer; and At least one bipolar electrode is disposed between the positive terminal electrode and the negative terminal electrode, The pair of sheet members respectively include: A pair of insulating layers; a metal layer disposed between the pair of insulating layers; and a peeling portion obtained by peeling a part of each of the pair of insulating layers from the metal layer; The release portion of one of the pair of sheet members is disposed so as to face the negative terminal electrode, and the release portion of the other of the pair of sheet members is disposed so as to face the positive terminal electrode.

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