Power storage cell, power storage device, and method for manufacturing power storage device

Abstract

An electricity storage element (2) is provided with a positive electrode (11), a negative electrode (12), a separator (13), and a spacer (14). The positive electrode (11) has a first current collector (20) and a positive electrode active material layer (22) provided on one face (20a) of the first current collector (20). The negative electrode (12) has a second current collector (21) and a negative electrode active material layer (23) provided on one face (21a) of the second current collector (21). The separator (13) has a base material layer (13a), a first adhesive layer (13b), and a second adhesive layer (13c). One face (20a) of the first current collector (20) is adhered to the first adhesive layer (13b) in a rim portion (13e) of the separator (13). The spacer (14) is adhered to the second adhesive layer (13c) in the rim portion (13e) of the separator (13).

Description

TECHNICAL FIELD

[0001] The present disclosure relates to a power storage cell, a power storage device, and a manufacturing method of a power storage device. BACKGROUND

[0002] Patent Document 1 discloses a power storage element provided with a bagged positive electrode plate in which an adhesive layer provided on the surface of a separator is adhered to a tab of a positive electrode plate.

[0003] Prior art documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2018-152236 SUMMARY

[0006] Problems to be solved by the invention

[0007] In the above-described power storage element, when the adhesion of the separator to the tab decreases, the separator can shrink.

[0008] The present disclosure provides a power storage cell, a power storage device, and a manufacturing method of a power storage device that can suppress shrinkage of a separator.

[0009] Solution to the problem

[0010] The power storage cell according to an aspect of the present disclosure includes a positive electrode having a first current collector and a positive electrode active material layer provided on one face of the first current collector; a negative electrode having a second current collector and a negative electrode active material layer provided on one face of the second current collector, the negative electrode being stacked with the positive electrode in such a manner that the negative electrode active material layer opposes the positive electrode active material layer; a separator having a base material layer, the separator being disposed between the positive electrode and the negative electrode; and a spacer formed between the first current collector and the second current collector, the spacer being joined to at least one of the first current collector and the second current collector, the separator having, when viewed in a stacking direction of the positive electrode and the negative electrode, a central portion overlapping the positive electrode active material layer and the negative electrode active material layer, and a peripheral portion surrounding the central portion and not overlapping the positive electrode active material layer and the negative electrode active material layer, the separator having, at least in the peripheral portion of the separator, a first adhesive layer provided on a first face of the base material layer, and a second adhesive layer provided on a second face of the base material layer, either one of the first current collector and the second current collector being adhered to the first adhesive layer in the peripheral portion of the separator, the spacer being adhered to the second adhesive layer in the peripheral portion of the separator.

[0011] According to the power storage cell described above, the rim portion of the separator is bonded to either one of the first and second current collectors and the spacer, and thus, shrinkage of the separator can be suppressed.

[0012] The first bonding layer and the second bonding layer can be provided on the central portion of the separator. In this case, the first bonding layer and the second bonding layer can be bonded to the positive active material layer and the negative active material layer.

[0013] One of the first bonding layer and the second bonding layer can be bonded to one of the positive active material layer and the negative active material layer, and the other of the first bonding layer and the second bonding layer can be bonded to the other of the positive active material layer and the negative active material layer. In this case, even when the active material layer shrinks, the decrease in the contact area between the bonding layer and the active material layer can be suppressed.

[0014] The spacer can be bonded to the end surface of the first bonding layer and the end surface of the second bonding layer. In this case, the adhesion between the separator and the spacer is improved.

[0015] At least one of the first bonding layer and the second bonding layer can include a thermosetting adhesive. In this case, even when the power storage cell is heated after the thermosetting adhesive is cured, the thermosetting adhesive does not melt. Thus, the separator can be more reliably attached to either one of the first and second current collectors or the spacer.

[0016] The first bonding layer can be bonded to the one face of the second current collector. In the negative electrode, at the interface between the second current collector and the spacer, the spacer can be deteriorated by a reaction between the spacer and the electrolyte using the second current collector as a catalyst, and the adhesion between the spacer and the second current collector can decrease. Even in this case, by disposing the end portion of the separator at the interface between the second current collector and the spacer, the progress of the deterioration of the spacer can be delayed.

[0017] In the current collector of the first and second current collectors to which the first bonding layer is bonded, the surface roughness of the one face can be greater than the surface roughness of the other face opposite to the one face. In this case, the contact area between the first bonding layer and the one face increases, and thus, the adhesion between the first bonding layer and the one face is improved.

[0018] An electricity storage device according to an aspect of the present disclosure includes a laminate including a plurality of power storage cells stacked, the plurality of power storage cells including the power storage cell described above.

[0019] According to the above-described power storage device, shrinkage of the separator can be suppressed.

[0020] Also, the above-described power storage device can further include a metal layer provided on an outer surface of the separator. In this case, water vapor or oxygen or the like can be prevented from permeating through the separator.

[0021] Also, the above-described power storage device can further include a pair of constraint plates that sandwich the stack in the stacking direction, and a current collector plate that is disposed between each of the pair of constraint plates and the stack. In this case, the stack can be additionally constrained in the stacking direction by the pair of constraint plates.

[0022] A manufacturing method of a power storage device according to an aspect of the present disclosure includes: a step of preparing a first electrode unit having a first electrode including a first current collector and a first active material layer provided on one face of the first current collector; a step of preparing a second electrode unit having a second electrode including a second current collector and a second active material layer provided on one face of the second current collector, and a separator joined to a peripheral portion of the second current collector, the second electrode having a polarity different from that of the first electrode; a step of alternately stacking the first electrode unit and the second electrode unit with the second active material layer opposing the first active material layer via a separator having a base material layer, a first adhesive layer provided on a first face of the base material layer, and a second adhesive layer provided on a second face of the base material layer, a peripheral portion of the separator being disposed between the one face of the second current collector and the separator, the first adhesive layer in the peripheral portion of the separator opposing the one face of the second current collector, and the second adhesive layer in the peripheral portion of the separator opposing the separator; a step of forming a seal body that seals a space between the first electrode and the second electrode by fusion bonding the separators adjacent to each other in a stacking direction of the first electrode unit and the second electrode unit; and a step of performing charge and discharge of a power storage device including the first electrode, the second electrode, and the separator after the seal body is formed.

[0023] According to the above-described manufacturing method of a power storage device, the first adhesive layer and the second adhesive layer respectively exhibit adhesiveness in the step of alternately stacking the first electrode unit and the second electrode unit or the step of performing charge and discharge of the power storage device, for example, due to heat generation of the power storage device or moisture or the like contained therein during charge and discharge. As a result, the first adhesive layer in the peripheral portion of the separator adheres to the one face of the first current collector. The second adhesive layer in the peripheral portion of the separator adheres to the separator. Thus, shrinkage of the separator can be suppressed.

[0024] Effects of the invention

[0025] According to the present disclosure, a power storage cell, a power storage device, and a manufacturing method of a power storage device capable of suppressing shrinkage of a separator can be provided. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 is a schematic cross-sectional view illustrating a power storage device of an embodiment.

[0027] Figure 2 (a) to (d) of FIG. 1 are cross-sectional views illustrating each process of a manufacturing method of a power storage device of an embodiment.

[0028] Figure 3 is a cross-sectional view illustrating one process of a manufacturing method of a power storage device of an embodiment.

[0029] Figure 4 is a schematic cross-sectional view illustrating a power storage device of another embodiment.

[0030] Figure 5 is a schematic cross-sectional view illustrating a power storage device of another embodiment.

[0031] Figure 6 is a schematic cross-sectional view illustrating a part of a power storage device of another embodiment. DETAILED DESCRIPTION

[0032] Hereinafter, an embodiment of the present disclosure will be described in detail with reference to the drawings. In the description of the drawings, the same reference numerals are used for the same or equivalent elements, and repetitive description is omitted.

[0033] Figure 1 is a schematic cross-sectional view illustrating a power storage device of an embodiment. Figure 1 The power storage device 1 illustrated is, for example, a power storage module of a battery for various vehicles such as a forklift, a hybrid car, an electric car, and the like. The power storage device 1 is, for example, a secondary battery such as a nickel-hydrogen secondary battery or a lithium-ion secondary battery. The power storage device 1 can be an electric double layer capacitor or a full solid battery. In the present embodiment, a case where the power storage device 1 is a lithium-ion secondary battery is exemplified.

[0034] The power storage device 1 is configured to include a battery stack 5 (stack) in which a plurality of power storage cells 2 are stacked in a stacking direction. Hereinafter, the stacking direction of the plurality of power storage cells 2 is simply referred to as the stacking direction. The power storage device 1 has, for example, a rectangular shape with a side of 50 cm or more when viewed from the stacking direction. As illustrated in FIG. 1, the power storage device 1 includes a plurality of power storage cells 2, a plurality of separators 3, and a plurality of current collectors 4. Figure 1As shown, each of the power storage cells 2 includes a positive electrode 11, a negative electrode 12, a separator 13, and a spacer 14. The positive electrode 11 includes a first current collector 20 and a positive electrode active material layer 22 provided on one face 20a of the first current collector 20. The positive electrode 11 is, for example, an electrode having a rectangular shape as viewed in the stacking direction. The negative electrode 12 includes a second current collector 21 and a negative electrode active material layer 23 provided on one face 21a of the second current collector 21. The negative electrode 12 is, for example, an electrode having a rectangular shape as viewed in the stacking direction. The negative electrode 12 is stacked with the positive electrode 11 in such a manner that the negative electrode active material layer 23 and the positive electrode active material layer 22 face each other in the stacking direction. That is, the direction in which the positive electrode 11 and the negative electrode 12 face each other coincides with the stacking direction. In the present embodiment, the positive electrode active material layer 22 and the negative electrode active material layer 23 are each formed in a rectangular shape. The negative electrode active material layer 23 is formed to be larger than the positive electrode active material layer 22 by one turn, and the entire formation region of the positive electrode active material layer 22 is located within the formation region of the negative electrode active material layer 23 as viewed in the stacking direction.

[0035] The first current collector 20 has another face 20b as a face opposite to the one face 20a. The positive electrode active material layer 22 is not formed on the other face 20b. The second current collector 21 has another face 21b as a face opposite to the one face 21a. The negative electrode active material layer 23 is not formed on the other face 21b. The power storage cells 2 are stacked in such a manner that the other face 20b of the first current collector 20 and the other face 21b of the second current collector 21 contact each other, thereby constituting the battery stack 5. Thus, the plurality of power storage cells 2 are electrically connected in series. In the battery stack 5, a pseudo-bipolar electrode 10 having the first current collector 20 and the second current collector 21 as electrode bodies in contact with each other is formed by the power storage cells 2, 2 adjacent in the stacking direction. That is, one bipolar electrode 10 includes the first current collector 20, the second current collector 21, the positive electrode active material layer 22, and the negative electrode active material layer 23. The first current collector 20 is disposed as a terminal electrode at one end in the stacking direction. The second current collector 21 is disposed as a terminal electrode at the other end in the stacking direction.

[0036] The first and second current collectors 20 and 21 (hereinafter, also simply referred to as "current collectors") are chemically inert electric conductors for allowing current to continuously flow through the positive electrode active material layer 22 and the negative electrode active material layer 23 during discharge or charge of the lithium-ion secondary battery. As a material constituting the current collector, for example, a metallic material, a conductive resin material, a conductive inorganic material, or the like can be used. As the conductive resin material, for example, a resin obtained by adding a conductive filler to a conductive polymer material or a non-conductive polymer material as needed, or the like can be given. The current collector can have a plurality of layers including one or more layers containing the above-described metallic material or conductive resin material. The surface of the current collector can be coated with a known protective layer. The coating layer can also be formed on the surface of the current collector by a known method such as plating treatment or spraying. For example, a carbon film can be provided on the surface (e.g., one face 20a and one face 21a) of the current collector. The current collector can be formed in a plate shape, a foil shape, a sheet shape, a film shape, a mesh shape, or the like. In the case where the current collector is a metal foil, for example, an aluminum foil, a copper foil, a nickel foil, a titanium foil, or a stainless steel foil, or the like can be used. In the case where an aluminum foil, a copper foil, or a stainless steel foil is used as the current collector, the mechanical strength of the current collector can be ensured. The current collector can also be an alloy foil or a clad foil of the above-described metal, or a current collector in which a metal plating film is formed on one face of a metal foil. In the present embodiment, the first current collector 20 is an aluminum foil, and the second current collector 21 is a copper foil. In the case where a foil-shaped current collector is used, the thickness thereof can be, for example, 1 μm to 100 μm.

[0037] The positive electrode active material layer 22 contains a positive electrode active material capable of occluding and releasing a charge carrier such as a lithium ion. As the positive electrode active material, for example, a lithium complex metal oxide having a layered rock salt structure, a metal oxide having a spinel structure, a polyanion-based compound, or the like can be used. Two or more kinds of positive electrode active materials can also be used together. In the present embodiment, the positive electrode active material layer 22 contains an olivine-type lithium iron phosphate (LiFeP04) as a polyanion-based compound.

[0038] The negative electrode active material layer 23 can be a simple substance, an alloy, or a compound capable of occluding and releasing a charge carrier such as a lithium ion, and can be used without particular limitation. For example, as the negative electrode active material, Li, carbon, a metal compound, an element or a compound thereof capable of alloying with lithium, or the like can be given. As the carbon, for example, natural graphite, artificial graphite, hard carbon (difficultly graphitizable carbon), soft carbon (easily graphitizable carbon), or the like can be given. As the artificial graphite, for example, high-orientation black lead, mesocarbon microbeads, or the like can be given. As examples of the element capable of alloying with lithium, for example, silicon, tin, or the like can be given. In the present embodiment, the negative electrode active material layer 23 contains graphite as the carbon.

[0039] The positive electrode active material layer 22 and the negative electrode active material layer 23 (hereinafter also simply referred to as "active material layer") can each further include, as necessary, a conductive aid for improving electrical conductivity, a binder, an electrolyte (polymer matrix, ion-conducting polymer, electrolytic solution, etc.), an electrolyte-supporting salt (lithium salt) for improving ion conductivity, and the like. The components included in the active material layer or the compounding ratio of the components and the thickness of the active material layer are not particularly limited, and can be appropriately referred to the existing publicly known insights regarding lithium ion secondary batteries. The thickness of the active material layer is, for example, 2 to 150 μm. In order to form the active material layer on the surface of the current collector, a method known since old such as a roll coating method can be used. In order to improve the thermal stability of the positive electrode 11 or the negative electrode 12, a heat-resistant layer can also be provided on the surface (one side or both sides) of the current collector or the surface of the active material layer. The heat-resistant layer includes, for example, inorganic particles and a binder, and can also include an additive such as a thickening agent in addition thereto.

[0040] The conductive aid is added in order to improve the electrical conductivity of the positive electrode 11 or the negative electrode 12. The conductive aid is, for example, acetylene black, carbon black, graphite, or the like.

[0041] As the binder, a fluorine-containing resin such as polyvinylidene fluoride, polytetrafluoroethylene, or fluorine rubber; a thermoplastic resin such as polypropylene or polyethylene; an imide-based resin such as polyimide or polyamide-imide; a resin containing an alkoxysilyl group; an acrylic resin such as polyacrylic acid or polymethacrylic acid; styrene-butadiene rubber (SBR); carboxymethyl cellulose (CMC); an alginate salt such as sodium alginate or ammonium alginate; a water-soluble cellulose ester crosslinking product; and a starch-acrylic acid graft polymer can be exemplified. These binders can be used alone or in a plurality. A solvent such as water or N-methyl-2-pyrrolidone (NMP) is used, for example.

[0042] The separator 13 separates the positive electrode 11 from the negative electrode 12, not only to prevent short-circuiting due to contact of the two electrodes, but also to allow the passage of charge carriers such as lithium ions. The separator 13 is disposed between the positive electrode 11 and the negative electrode 12. The separator 13 prevents short-circuiting between adjacent bipolar electrodes 10, 10 when the power storage cells 2 are stacked.

[0043] The separator 13 has a base material layer 13a, a first adhesive layer 13b provided on a first surface 13aa of the base material layer 13a, and a second adhesive layer 13c provided on a second surface 13ab of the base material layer 13a which is opposite to the first surface 13aa. The separator 13 has, when viewed in the stacking direction of the positive electrode 11 and the negative electrode 12, a central portion 13d overlapping the positive electrode active material layer 22 and the negative electrode active material layer 23, a peripheral portion 13e surrounding the central portion 13d of the separator 13 and not overlapping the positive electrode active material layer 22 and the negative electrode active material layer 23, and a connecting portion connecting the central portion 13d and the peripheral portion 13e of the separator 13. The first adhesive layer 13b and the second adhesive layer 13c are provided at least on the peripheral portion 13e of the separator 13.

[0044] In the present embodiment, the first adhesive layer 13b is also provided on the central portion 13d of the separator 13. That is, the first adhesive layer 13b is provided on the entire surface of the first surface 13aa of the base material layer 13a. The first adhesive layer 13b is adhered to the positive electrode active material layer 22. The first adhesive layer 13b prevents positional displacement between the positive electrode 11 and the base material layer 13a.

[0045] In the present embodiment, the second adhesive layer 13c is also provided on the central portion 13d of the separator 13. That is, the second adhesive layer 13c is provided on the entire surface of the second surface 13ab of the base material layer 13a. The second adhesive layer 13c is adhered to the negative electrode active material layer 23. The second adhesive layer 13c prevents positional displacement between the negative electrode 12 and the base material layer 13a.

[0046] The base material layer 13a can be, for example, a porous sheet or a nonwoven fabric including a polymer that absorbs and holds an electrolyte. As a material constituting the base material layer 13a, for example, a porous film including polypropylene (PP) is used. The material constituting the base material layer 13a can also be a woven fabric or a nonwoven fabric including polypropylene or methyl cellulose, or the like. The base material layer 13a can have a single-layer structure or a multi-layer structure. The multi-layer structure can have, for example, an adhesive layer, a ceramic layer as a heat-resistant layer, or the like. The base material layer 13a can be impregnated with an electrolyte. The base material layer 13a itself can also be constituted of a high-molecular solid electrolyte or an inorganic solid-type electrolyte, or the like.

[0047] As the electrolyte impregnated in the base material layer 13a, for example, a liquid electrolyte (electrolytic solution) including a nonaqueous solvent and an electrolyte salt dissolved in the nonaqueous solvent, or a high-molecular gel electrolyte including an electrolyte held in a polymer matrix, or the like can be cited.

[0048] In the case where the electrolytic solution is impregnated in the substrate layer 13a, as the electrolyte salt thereof, known lithium salts such as LiCIO4, LiAsF6, LiPF6, LiBF4, LiCF3SO3, LiN(FSO2)2, LiN(CF3SO2)2, and the like can be used. In addition, as the non-aqueous solvent, known solvents such as cyclic carbonate-based, cyclic ester-based, chain carbonate-based, chain ester-based, ether-based, and the like can be used. Furthermore, two or more of these known solvent materials can be used in combination.

[0049] Each of the first adhesive layer 13b and the second adhesive layer 13c can include a thermosetting adhesive or a thermoplastic adhesive, and can include, for example, an adhesive that is cured by reacting with moisture such as an electrolytic solution (moisture-curable adhesive). The moisture-curable adhesive can be cured at a temperature higher than the use temperature (for example, room temperature) of the power storage device 1, for example. In the case where an ester-based electrolytic solution is used, the moisture-curable adhesive can be cured at 80°C or lower. The thermosetting adhesive can include a thermosetting resin such as an epoxy resin, a phenol resin, and the like. The thermoplastic adhesive can include a thermoplastic resin such as polyethylene, polypropylene, polyvinylidene fluoride (PVDF), and the like. The first adhesive layer 13b and the second adhesive layer 13c can each be formed by applying an adhesive.

[0050] The spacer 14 is formed at least between the first current collector 20 and the second current collector 21, and is joined or fixed to the first current collector 20 and the second current collector 21. The spacer 14 includes an insulating material, and prevents short-circuiting by insulating between the first current collector 20 and the second current collector 21. In the present embodiment, the spacer 14 includes acid-modified polyethylene as a resin as the insulating material. In addition, as the material of the spacer 14, in addition to acid-modified polyethylene, polyethylene (PE), polystyrene (PS), ABS resin, polypropylene (PP), modified polypropylene (modified PP), and acrylonitrile styrene (AS) resin, for example, can be used.

[0051] In the present embodiment, the spacer 14 is a frame that extends along at least one of the edge portion 20e of the first current collector 20 and the edge portion 21e of the second current collector 21, and surrounds at least one of the positive electrode active material layer 22 and the negative electrode active material layer 23.

[0052] In the present embodiment, the spacer 14 also functions as a sealing portion that seals the space S between the positive electrode 11 and the negative electrode 12. In the present embodiment, the spacer 14 disposed to each power storage cell 2 has a portion disposed between the pair of current collectors and a portion extending further outward than the edge portion of the current collector, and the outwardly extending portions of the spacers 14 adjacent in the stacking direction of the battery stack 5 are joined to each other and integrated. A plurality of spacers 14 are integrated to form a sealing body 14a. The electrolyte (electrolytic solution) impregnated in the base material layer 13a of the separator 13 is housed in the space S surrounded by the spacer 14, the positive electrode 11, and the negative electrode 12. The spacer 14 is rectangular in frame shape when viewed in the stacking direction, and is bonded to the edge portion 21e of the second current collector 21. The sealing body 14a extends in the stacking direction from the first current collector 20 disposed at one end in the stacking direction of the battery stack 5 to the second current collector 21 disposed at the other end in the stacking direction. The sealing body 14a is a tubular member. As described later, such a sealing body 14a is formed by fusion bonding a plurality of resin frames 25 to each other (see FIG. 6). Figure 2

[0053] The spacer 14 prevents the permeation of the electrolyte by sealing the space S between the positive electrode 11 and the negative electrode 12. In addition, the spacer 14 prevents the intrusion of moisture from the outside of the power storage device 1 into the space S by sealing the space S between the positive electrode 11 and the negative electrode 12. Furthermore, the spacer 14 prevents the leakage of gas generated from the positive electrode 11 or the negative electrode 12, for example, by charge and discharge reactions, to the outside of the power storage device 1.

[0054] In the present embodiment, one face 20a of the first current collector 20 is bonded to the first bonding layer 13b in the edge portion 13e of the separator 13. That is, the one face 20a of the first current collector 20 includes a bonding face 20aa bonded to the first bonding layer 13b. The one face 20a of the first current collector 20 includes a formed region in which the positive electrode active material layer 22 is formed, and a non-formed region in which the positive electrode active material layer 22 is not formed. The non-formed region is provided around the formed region, and includes the bonding face 20aa bonded to the first bonding layer 13b.

[0055] The spacer 14 is bonded to the second bonding layer 13c in the edge portion 13e of the separator 13. The spacer 14 can also be bonded to the end face 13bs of the first bonding layer 13b and the end face 13cs of the second bonding layer 13c. The edge portion 13e of the separator 13 is sandwiched between the bonding face 20aa and the spacer 14. The edge portion 13e of the separator 13 is embedded in the spacer 14.

[0056] According to the power storage device 1 and the power storage cell 2 of the present embodiment, the edge portion 13e of the separator 13 is bonded to the first current collector 20 and the spacer 14, and thus the edge portion 13e of the separator 13 is fixed, and the shrinkage or positional displacement of the separator 13 can be suppressed.​

[0057] The edge portion 13e of the separator 13 of the present embodiment is adhered to the current collector not only on one surface but also on the other surface. Since the spacer 14 is arranged in a fixed state at the end portion of the power storage cell 2, even if the adhesion of the edge portion 13e of the separator 13 to the current collector decreases, the edge portion 13e of the separator 13 is held by the spacer 14. Therefore, in the present embodiment, compared to a case where the edge portion 13e of the separator 13 is not adhered to any portion or a case where the edge portion 13e of the separator 13 is adhered to the current collector only, the shrinkage of the separator 13 is suppressed. Thus, the short circuit of the positive electrode and the negative electrode due to the thermal shrinkage of the separator 13 is suppressed. In addition, it is possible that a gap is generated between the electrode and the separator due to the repeated expansion and shrinkage of the positive active material layer 22 or the negative active material layer 23, by the influence of residual stress or the like, but by the first adhesive layer 13b and the second adhesive layer 13c, the expansion of the distance between the one surface 20a of the first current collector 20 and the one surface 21a of the second current collector 21 at the central portion 13d of the power storage device 1 is suppressed, and the decrease in the battery performance is suppressed.

[0058] If the first adhesive layer 13b and the second adhesive layer 13c are provided at the central portion 13d of the separator 13, respectively, the first adhesive layer 13b and the second adhesive layer 13c can be adhered to the positive active material layer 22 and the negative active material layer 23, respectively.

[0059] Although it is possible that a gap is generated between the electrode and the separator due to the repeated expansion and shrinkage of the positive active material layer 22 or the negative active material layer 23, by the influence of residual stress or the like, since the first adhesive layer 13b is adhered to the positive active material layer 22 and the second adhesive layer 13c is adhered to the negative active material layer 23, the expansion of the distance between the positive active material layer 22 and the negative active material layer 23 is suppressed. As a result, the increase in the electric resistance value of the power storage device 1 is reduced, and thus the decrease in the capacity of the power storage device 1 is suppressed. In addition, in a case where the size of the power storage device 1 is large when viewed in the stacking direction as in the present embodiment, the expansion of the distance between the current collectors at the central portion 13d of the power storage device 1 is increased. Even in such a case, since the first adhesive layer 13b and the second adhesive layer 13c are adhered to the positive active material layer 22 and the negative active material layer 23, respectively, at the central portion 13d of the separator 13, the expansion of the distance between the one surface 20a of the first current collector 20 and the one surface 21a of the second current collector 21 at the central portion 13d of the power storage device 1 when viewed in the stacking direction is suppressed.

[0060] When the spacer 14 is bonded to the end face 13bs of the first adhesive layer 13b and the end face 13cs of the second adhesive layer 13c, the bonding area between the spacer 13 and the spacer 14 becomes larger, thus the spacer 13 can be bonded to the spacer 14 more firmly.

[0061] When at least one of the first adhesive layer 13b and the second adhesive layer 13c contains a thermosetting adhesive, the thermosetting adhesive will not melt even if the battery cell 2 is heated after the thermosetting adhesive has cured. Therefore, the spacer 13 can be more reliably installed onto the first current collector 20 or the spacer 14.

[0062] Figure 2 (a) to (d) and Figure 3 This is a cross-sectional view showing the various steps of a method for manufacturing an energy storage device according to one embodiment. The energy storage device 1 can be manufactured, for example, as follows.

[0063] (Preparation of the positive electrode unit)

[0064] First, such as Figure 2 As shown in (a), a positive electrode unit U1 (first electrode unit) is prepared. The positive electrode unit U1 has a positive electrode 11 (first electrode), which has a first current collector 20 and a positive electrode active material layer 22 (first active material layer) disposed on one surface 20a of the first current collector 20. In this embodiment, the positive electrode unit U1 has a separator 13 disposed on one surface 20a of the first current collector 20. The separator 13 is configured to cover the positive electrode active material layer 22. The separator 13 has a substrate layer 13a, a first adhesive layer 13b disposed on a first surface 13aa of the substrate layer 13a, and a second adhesive layer 13c disposed on a second surface 13ab of the substrate layer 13a. The first adhesive layer 13b in the edge 13e of the separator 13 is configured to face one surface 20a of the first current collector 20. The first adhesive layer 13b in the edge 13e of the separator 13 can also be bonded to one surface 20a of the first current collector 20. In this process, when the first adhesive layer 13b and the second adhesive layer 13c of the separator 13 contain a thermosetting adhesive, the thermosetting adhesive is uncured, but it is adhesive to one surface 20a of the first current collector 20.

[0065] (Preparation of the negative electrode unit)

[0066] In addition, such as Figure 2As shown in (b), a negative electrode unit U2 (second electrode unit) is prepared. The negative electrode unit U2 has: a negative electrode 12 (a second electrode having a polarity different from that of the first electrode), which has a second current collector 21 and a negative electrode active material layer 23 (second active material layer) disposed on one surface 21a of the second current collector 21; and a resin frame 25 (spacer) which is joined to the edge 21e of the second current collector 21. Electrolyte may also be supplied to the resin frame 25.

[0067] (Stacking of positive and negative electrode units)

[0068] Next, as Figure 2 As shown in (c), the positive electrode unit U1 and the negative electrode unit U2 are alternately stacked such that the negative electrode active material layer 23 faces the positive electrode active material layer 22 through the separator 13. The edge 13e of the separator 13 is disposed between a surface 20a of the first current collector 20 and the resin frame 25. The first adhesive layer 13b in the edge 13e of the separator 13 faces the surface 20a of the first current collector 20. The second adhesive layer 13c in the edge 13e of the separator 13 faces the resin frame 25. A plurality of resin frames 25 are arranged spaced apart from each other in the stacking direction of the positive electrode unit U1 and the negative electrode unit U2.

[0069] (Formation of a sealing body)

[0070] Next, as Figure 2 As shown in (d), a sealing body 14a is formed by fusing adjacent resin frames 25 in the stacking direction of positive electrode unit U1 and negative electrode unit U2 to each other. For example, adjacent resin frames 25 are fused to each other by pressing a hot plate against the outer peripheral surface 25s of each resin frame 25.

[0071] (Charging and discharging of the energy storage device)

[0072] Next, as Figure 3 As shown, the energy storage device 1, comprising a positive electrode 11, a negative electrode 12, and a separator 13, is charged and discharged (activation process). In this embodiment, the charging and discharging is performed while the positive electrode 11, negative electrode 12, and separator 13 are constrained in the stacking direction. The energy storage device 1 is constrained by sandwiching it between a pair of constraining members 30 in the stacking direction. A positive current collector plate 40 electrically connected to the first current collector 20 is disposed between one constraining member 30 and a first current collector 20 disposed at one end in the stacking direction. An insulating plate 41 is disposed between the positive current collector plate 40 and one constraining member 30. A negative current collector plate 50 electrically connected to the second current collector 21 is disposed between the other constraining member 30 and a second current collector 21 disposed at the other end in the stacking direction. An insulating plate 51 is disposed between the negative current collector plate 50 and the other constraining member 30.

[0073] The charge and discharge (initial charge and discharge) of the power storage device 1 is performed, for example, by arranging the power storage device 1 restrained by the pair of restraint members 30 in a thermostat tank and causing a current to flow between the positive current collector plate 40 and the negative current collector plate 50.

[0074] After the activation process, the restraint by the pair of restraint members 30 is released, and the power storage device 1 is taken out. In this way, the power storage device 1 can be manufactured.

[0075] According to the manufacturing method of the power storage device 1 of the present embodiment, in the case where the first adhesive layer 13b and the second adhesive layer 13c contain a thermosetting adhesive, in the process of performing the charge and discharge of the power storage device 1, the first adhesive layer 13b and the second adhesive layer 13c are respectively cured by the heat generation (for example, 90°C) of the power storage device 1 at the time of the charge and discharge. As a result, the first adhesive layer 13b in the edge portion 13e of the separator 13 is adhered to the adhesive surface 20aa of the one face 20a of the first current collector 20. The second adhesive layer 13c in the edge portion 13e of the separator 13 is adhered to the spacer 14. The edge portion 13e of the separator 13 is sandwiched between the adhesive surface 20aa of the one face 20a of the first current collector 20 and the spacer 14. Thereby, the shrinkage of the separator 13 can be suppressed.

[0076] In the case where the first adhesive layer 13b and the second adhesive layer 13c contain a thermoplastic adhesive, in the stacking process of the positive electrode unit and the negative electrode unit, the first adhesive layer 13b is adhered to the adhesive surface 20aa and the second adhesive layer 13c is adhered to the spacer 14 by thermal compression bonding. In the case where the first adhesive layer 13b and the second adhesive layer 13c contain a moisture curing type adhesive, in the stacking process of the positive electrode unit and the negative electrode unit, the first adhesive layer 13b is adhered to the adhesive surface 20aa and the second adhesive layer 13c is adhered to the spacer 14 by the reaction with the moisture of the electrolyte solution dropped in the resin frame 25.

[0077] Figure 4 is a schematic cross-sectional view showing a power storage device of another embodiment. Figure 4 The power storage device 1a shown has Figure 1The power storage device 1, a pair of restraint plates 31, a positive electrode current collecting plate 40, and a negative electrode current collecting plate 50. The pair of restraint plates 31 sandwich the power storage device 1, the positive electrode current collecting plate 40, and the negative electrode current collecting plate 50 in the stacking direction of the battery stack 5. The pair of restraint plates 31 are linked to each other by fastening members such as bolts 32 and nuts 33, for example. The positive electrode current collecting plate 40 is disposed between one restraint plate 31 and the first current collector 20 disposed at one end in the stacking direction. An insulating plate 41 is disposed between the positive electrode current collecting plate 40 and one restraint plate 31. The negative electrode current collecting plate 50 is disposed between the other restraint plate 31 and the second current collector 21 disposed at the other end in the stacking direction. An insulating plate 51 is disposed between the negative electrode current collecting plate 50 and the other restraint plate 31.

[0078] The same effects as the power storage device 1 can also be obtained in the power storage device 1a. Furthermore, by the pair of restraint plates 31, it is possible to apply a restraint load to the battery stack 5 in the stacking direction. The power storage device 1a can be manufactured by the same method as the power storage device 1.

[0079] Figure 5 is a schematic cross-sectional view showing a power storage device of another embodiment. Figure 5 The power storage device 1b shown has the same configuration as the power storage device 1 except that the edge portion 13e of the separator 13 is not bonded to the one face 20a of the first current collector 20 but is bonded to the one face 21a of the second current collector 21. Figure 1 The power storage device 1b has the same configuration as the power storage device 1 except that the edge portion 13e of the separator 13 is not bonded to the one face 20a of the first current collector 20 but is bonded to the one face 21a of the second current collector 21. Figure 1 The power storage device 1b has the same configuration as the power storage device 1 except that the edge portion 13e of the separator 13 is not bonded to the one face 20a of the first current collector 20 but is bonded to the one face 21a of the second current collector 21.

[0080] The same effects as the power storage device 1 are obtained in the power storage device lb. In the negative electrode 12, at the interface of the second current collector 21 and the spacer 14, the deterioration of the spacer 14 is sometimes accelerated due to a reaction of the spacer 14 (for example, resin) with the electrolyte with the second current collector 21 (for example, copper) as a catalyst. Even in such a case, by disposing the rim portion 13e of the separator 13 at the interface of the second current collector 21 and the spacer 14, the deterioration of the spacer 14 can be delayed. In addition, in a case where the negative electrode active material layer 23 of the negative electrode 12 is graphite and the positive electrode active material layer 22 of the positive electrode 11 is olivine-type lithium iron phosphate, the negative electrode active material layer 23 becomes a layer that is softer than the positive electrode active material layer 22. Therefore, in the present embodiment in which the separator 13 is bonded to the second current collector 21 on which the negative electrode active material layer 23 is formed, the separator 13 is prevented from being damaged by the corner of the active material layer. In addition, since the separator 13 is provided so as to cover the negative electrode active material layer 23 having a larger area than the positive electrode active material layer 22, the peeling of the negative electrode active material layer 23 from the second current collector 21 is prevented.

[0081] The power storage device lb can be manufactured by the same method as the power storage device 1. In the preparation process of the positive electrode unit, a positive electrode unit including the positive electrode 11 and the resin frame 25 is prepared. In the preparation process of the negative electrode unit, a negative electrode unit including the negative electrode 12 and the separator 13 is prepared. After the electrolyte is supplied into the resin frame 25 of the positive electrode unit, the positive electrode unit and the negative electrode unit are stacked.

[0082] Figure 6 is a schematic cross-sectional view showing a part of a power storage device of another embodiment. Figure 6 The power storage device shown in the drawing has the same configuration as the power storage device 1b except that one face 20a of the first current collector 20 is subjected to roughening. Figure 1The region subjected to roughening can be only the bonding surface 20aa, but in the present embodiment, the entire one surface 20a of the first current collector 20 is subjected to roughening. The surface roughness (arithmetic average roughness Ra) of the one surface 20a of the first current collector 20 is greater than the surface roughness of the other surface 20b of the first current collector 20. In the case where the entire one surface 20a of the first current collector 20 is subjected to roughening, it is only necessary that the surface roughness of the entire one surface 20a of the first current collector 20 be greater than the surface roughness of the entire other surface 20b of the first current collector 20. In the case where only the bonding surface 20aa of the first current collector 20 is subjected to roughening, it is only necessary that the surface roughness of the bonding surface 20aa of the first current collector 20 be greater than the surface roughness of the entire other surface 20b of the first current collector 20. The surface roughness of the one surface 20a is, for example, 50 to 300 μm. The other surface 20b is, for example, a smooth surface, but can also be roughened. A plurality of protrusions 20p protruding in the stacking direction are provided on the one surface 20a, for example. The protrusions 20p are disposed within the first bonding layer 13b. That is, the height of the protrusions 20p is smaller than the thickness of the first bonding layer 13b. The first bonding layer 13b enters into the recesses formed between adjacent protrusions 20p, thereby exerting an anchoring effect.

[0083] The protrusions 20p have, for example, a tapered portion between the base end and the top end. In other words, the protrusions 20p have an overhang portion between the base end and the top end. In still other words, the protrusions 20p have an expanding portion whose diameter increases from the base end side toward the top end side, and a reducing portion whose diameter decreases from the base end side toward the top end side. With the plurality of protrusions 20p having the tapered portion, the anchoring effect can be further improved. Furthermore, Figure 6 The size, shape, and density of the protrusions 20p are not particularly limited. The protrusions 20p can be formed by electrolytic plating, or can be formed by etching. The protrusions 20p can also have, for example, a shape that tapers from the base end side toward the top end side.

[0084] In the power storage device 1 of the present embodiment, Figure 6 In the power storage device 1 of the present embodiment, the contact area between the first bonding layer 13b and the one surface 20a is increased, and thus the adhesion between the first bonding layer 13b and the one surface 20a is improved. Thus, the shrinkage of the separator 13 can be further suppressed.

[0085] The other surface 20b of the first current collector 20 is in contact with the other surface 21b of the second current collector 21 of the adjacent power storage cell 2. When the other surface 20b of the first current collector 20 and the other surface 21b of the second current collector 21 are smooth surfaces, the contact resistance between the first current collector 20 and the second current collector 21 can be reduced.

[0086] In the power storage device 1 of the present embodiment, Figure 4In the same manner as in the power storage device 1a, the surface roughness of one face 20a of the first current collector 20 can be greater than the surface roughness of the other face 20b of the first current collector 20. Figure 5 In the same manner as in the power storage device 1b, the surface roughness of one face 21a of the second current collector 21 can be greater than the surface roughness of the other face 21b of the second current collector 21.

[0087] The above, the preferred embodiments of the present disclosure are described in detail, but the present disclosure is not limited to the above-described embodiments.

[0088] The separator 13 can also be formed by applying a separator material to the positive electrode active material layer 22 or the negative electrode active material layer 23, for example. The first adhesive layer 13b can also be provided partially (non-continuously, discontinuously) on the first face 13aa of the base material layer 13a. The second adhesive layer 13c can also be provided partially (non-continuously, discontinuously) on the second face 13ab of the base material layer 13a.

[0089] The spacer 14 can also be a frame formed by combining a plurality of members in a manner surrounding the positive electrode active material layer 22 or the negative electrode active material layer 23. The spacer 14 can also be provided discontinuously along the edge portion 20e of the first current collector 20 or the edge portion 21e of the second current collector 21. In this case, the material of the spacer 14 can be reduced.

[0090] In the battery stack 5 in which the power storage cells 2 are stacked, the edge portion 20e of the first current collector 20 and the edge portion 21e of the second current collector 21 can also be configured to be exposed from the spacer 14. In this case, compared to a configuration in which the edge portion 20e of the first current collector 20 and the edge portion 21e of the second current collector 21 are buried in the spacer 14, the material of the spacer 14 can be reduced.

[0091] A metal layer 15 can also be formed on the outer surface (outer peripheral surface) of the spacer 14. The metal layer 15 extends in the stacking direction from the first current collector 20 disposed at one end in the stacking direction of the battery stack 5 to the second current collector 21 disposed at the other end in the stacking direction. The metal layer 15 can be laminated on the outer surface of the spacer 14 by the adhesive layer 16, for example, or can be formed in contact with the outer surface of the spacer 14 without the adhesive layer 16. In this case, the metal layer 15 can be formed by evaporation, for example, or can be formed by welding a metal foil to the outer surface of the spacer 14. The metal layer 15 is laminated on the outer surface of the sealant 14a (the outer surface of the spacer 14) by the adhesive layer 16, for example, after the sealant 14a is formed. A resin layer 17 can also be further formed on the outer surface of the metal layer 15.

[0092] By the metal layer 15, the water vapor or the gas such as oxygen can be inhibited from permeating the spacer 14. As a result, the decrease in the battery performance of the power storage device 1, 1a, 1b caused by the gas can be inhibited.

[0093] The spacer 14 can include a ceramic or the like as an insulating material. The spacer 14 can also include a material having a high elasticity such as rubber or the like.

[0094] The preparation of the negative electrode unit U2 can be performed before the preparation of the positive electrode unit U1, after the preparation of the positive electrode unit U1, or simultaneously with the preparation of the positive electrode unit U1.

[0095] The positive electrode unit U1 can also not have the separator 13. In this case, the separator 13 can be disposed between the positive electrode unit U1 and the negative electrode unit U2 in the stacking process of the positive electrode unit and the negative electrode unit.

[0096] In the power storage device 1, Figure 3 In the power storage device 1,

[0097] In the manufacture of the power storage device 1a, Figure 4 In the power storage device 1a, instead of the pair of constraint members 30, a pair of constraint plates 31, a bolt 32, and a nut 33 can be used in the activation process in which the charge and discharge of the power storage device 1a is performed. In this case, the constraint by the pair of constraint plates 31 does not need to be released after the activation process.

[0098] Explanation of reference signs

[0099] 1, 1a, 1b power storage device

[0100] 2 power storage cell

[0101] 5 battery stack (stack)

[0102] 11 positive electrode (first electrode)

[0103] 12 negative electrode (second electrode)

[0104] 13 separator

[0105] 13a base material layer

[0106] 13aa first surface

[0107] 13ab second surface

[0108] 13b first adhesive layer

[0109] 13c second adhesive layer

[0110] 13d central portion

[0111] 13e, 20e, 21e edge portion

[0112] 14 spacer

[0113] 15 metal layer

[0114] 20 first current collector

[0115] 20a, 21a one face

[0116] 20b, 21b the other face

[0117] 20aa, 21aa bonding face

[0118] 21 second current collector

[0119] 22 positive electrode active material layer (first active material layer)

[0120] 23 negative electrode active material layer (second active material layer)

[0121] 25 resin frame

[0122] 31 restraint plate

[0123] S space

[0124] U1 positive electrode unit (first electrode unit)

[0125] U2 negative electrode unit (second electrode unit)

Claims

1. A power storage cell characterized by comprising: Possessing: a positive electrode having a first current collector and a positive electrode active material layer provided on one face of the first current collector; a negative electrode having a second current collector and a negative electrode active material layer provided on one face of the second current collector, the negative electrode being stacked with the positive electrode in a manner that the negative electrode active material layer opposes the positive electrode active material layer; a separator having a base material layer, disposed between the positive electrode and the negative electrode; and a spacer formed between the first current collector and the second current collector, bonded to at least one of the first current collector and the second current collector, the separator, when viewed from a stacking direction of the positive electrode and the negative electrode, has a central portion overlapping the positive electrode active material layer and the negative electrode active material layer, and a peripheral portion surrounding the central portion and not overlapping the positive electrode active material layer and the negative electrode active material layer, the separator has, at least in the peripheral portion of the separator, a first adhesive layer provided on a first face of the base material layer, and a second adhesive layer provided on a second face of the base material layer, either one of the first current collector and the second current collector is bonded to the first adhesive layer in the peripheral portion of the separator, the spacer is bonded to the second adhesive layer in the peripheral portion of the separator.

2. The power storage cell according to claim 1, wherein the first adhesive layer and the second adhesive layer are respectively provided in the central portion of the separator.

3. The power storage cell according to claim 1, wherein one of the first adhesive layer and the second adhesive layer is bonded to one of the positive electrode active material layer and the negative electrode active material layer, the other of the first adhesive layer and the second adhesive layer is bonded to the other of the positive electrode active material layer and the negative electrode active material layer.

4. The power storage cell according to claim 2, wherein one of the first adhesive layer and the second adhesive layer is bonded to one of the positive electrode active material layer and the negative electrode active material layer, the other of the first adhesive layer and the second adhesive layer is bonded to the other of the positive electrode active material layer and the negative electrode active material layer.

5. The power storage cell according to any one of claims 1 to 4, wherein the spacer is bonded to an end face of the first adhesive layer and an end face of the second adhesive layer.

6. The power storage cell according to any one of claims 1 to 4, wherein at least one of the first adhesive layer and the second adhesive layer contains a thermosetting adhesive.

7. The power storage cell according to any one of claims 1 to 4, wherein the first adhesive layer is bonded to the one face of the second current collector.

8. The power storage cell according to any one of claims 1 to 4, wherein in the current collector of the first current collector and the second current collector that is bonded to the first adhesive layer, a surface roughness of the one face is greater than a surface roughness of the other face on the opposite side from the one face.

9. A power storage device, characterized by A laminate including a plurality of power storage cells stacked, The plurality of power storage cells include the power storage cell according to any one of claims 1 to 8.

10. The power storage device according to claim 9, wherein A metal layer is further provided on an outer surface of the spacer of the power storage cell.

11. The power storage device according to claim 9 or 10, wherein A pair of constraint plates sandwiching the laminate in a stacking direction of the laminate is further provided, and A current collector is provided between each of the pair of constraint plates and the laminate.

12. A method for manufacturing an electrical storage device, characterized by Comprising: a step of preparing a first electrode unit having a first electrode having a first current collector and a first active material layer provided on one face of the first current collector; a step of preparing a second electrode unit having a second electrode having a second current collector and a second active material layer provided on one face of the second current collector, and a spacer joined to a rim portion of the second current collector, the second electrode having a different polarity from the first electrode; a step of alternately stacking the first electrode unit and the second electrode unit with the second active material layer opposing the first active material layer via a separator having a base material layer, a first adhesive layer provided on a first face of the base material layer, and a second adhesive layer provided on a second face of the base material layer, a rim portion of the separator being disposed between the one face of the second current collector and the spacer, the first adhesive layer in the rim portion of the separator opposing the one face of the second current collector, and the second adhesive layer in the rim portion of the separator opposing the spacer; a step of forming a seal body sealing a space between the first electrode and the second electrode by fusion bonding the spacers adjacent to each other in a stacking direction of the first electrode unit and the second electrode unit; and a step of performing charge and discharge of a power storage device including the first electrode, the second electrode, and the separator after the formation of the seal body.

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