Method for manufacturing power storage device

Abstract

To improve adhesion to a seal resin, of a bipolar electrode comprising a bipolar current collector comprised of a rolled aluminum foil and an electrolytic copper foil.SOLUTION: A method for manufacturing a power storage device includes an electrode forming step. The electrode forming step includes an adhesion step, an unwinding step, a corona discharge step, carbon coat layer forming step, and an active material layer forming step. The adhesion step is a step of adhering an aluminum foil roll and an electrolytic copper foil together, thereby forming a laminate comprising an aluminum surface comprised of the aluminum foil roll and a copper surface comprised of the electrolytic copper foil. The unwinding step is a step of taking up the laminate in a roll shape, thereby forming a roll body. The corona discharge step is a step of performing corona discharge processing on the copper surface of the laminate which is taken out from the roll body. The carbon coat layer forming step is a step of forming a carbon coat layer on the copper surface after the corona discharge step.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a method for manufacturing an electricity storage device. [Background technology]

[0002] In recent years, research has been conducted on power storage devices using bipolar electrodes. The bipolar electrodes include a bipolar current collector having a positive electrode current collector and a negative electrode current collector, a positive electrode active material layer provided on the surface of the positive electrode current collector, and a negative electrode active material layer provided on the surface of the negative electrode current collector. Power storage devices using bipolar electrodes are expected to be superior to other power storage devices in terms of improving volumetric energy density and output.

[0003] Patent Document 1 discloses a bipolar electrode using a clad material made by rolling aluminum foil and copper foil as a bipolar current collector. In the case of the bipolar current collector of Patent Document 1, the aluminum layer made by rolling aluminum foil serves as a positive current collector, and the copper layer made by rolling copper foil serves as a negative current collector. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 08-007926 Summary of the Invention [Problem to be solved by the invention]

[0005] From the viewpoint of reducing the weight of a power storage device using a bipolar electrode and improving the volumetric energy density, it is preferable to form a thin bipolar current collector. As a method for making the bipolar current collector thin, for example, a method of laminating a rolled aluminum foil and an electrolytic copper foil is considered. However, a bipolar current collector having a structure of laminating a rolled aluminum foil and an electrolytic copper foil has a problem that the adhesion to the sealing resin that adheres the bipolar current collector is low in the power storage device. [Means for solving the problem]

[0006] A manufacturing method for an electricity storage device that solves the above-mentioned problems is a manufacturing method for an electricity storage device including a bipolar electrode and a sealing resin bonded to the bipolar electrode, the manufacturing method including an electrode forming step of forming the bipolar electrode, and an adhesion step of bonding the sealing resin to the bipolar electrode, the electrode forming step including a lamination step of bonding a rolled aluminum foil and an electrolytic copper foil together to form a laminate having an aluminum surface constituted by the rolled aluminum foil and a copper surface constituted by the electrolytic copper foil, a winding step of winding the laminate into a roll to form a roll body, a corona discharge step of performing a corona discharge treatment on the copper surface of the laminate unwound from the roll body, a carbon coat layer forming step of forming a carbon coat layer on the copper surface after the corona discharge step, and an active material layer forming step of forming an active material layer on each of a part of the aluminum surface and a part of the copper surface after the carbon coat layer forming step, and the adhesion step includes adhering the sealing resin to a part of the copper surface on which the active material layer is not formed and on which the carbon coat layer is formed.

[0007] According to the above-mentioned configuration, the rolling oil transferred to the electrolytic copper foil in the winding process is removed by the corona discharge treatment, so that the decrease in adhesive strength of the copper surface caused by the rolling oil can be suppressed. Furthermore, by forming a carbon coating layer on the copper surface, the adhesiveness of the carbon coating layer to the sealing resin can be ensured even after being exposed to a high-temperature environment for a long time in the electrode formation process. Therefore, the adhesiveness of the electrolytic copper foil side surface to the sealing resin is improved.

[0008] In the method for producing an electricity storage device, it is preferable that the corona discharge step and the carbon coat layer forming step are carried out successively. According to the above-mentioned configuration, it is possible to suppress the decrease of the hydrophilic functional groups generated by the corona discharge process, and as a result, it is possible to firmly bond the carbon coating layer to the laminate.

[0009] In the method for producing an electricity storage device, it is preferable that the corona discharge step and the carbon coat layer forming step are performed on both the aluminum surface and the copper surface of the laminate.

[0010] According to the above-mentioned configuration, the adhesive strength of the aluminum foil side can be suppressed from decreasing due to rolling oil and exposure to a high-temperature environment for a long time, similarly to the electrolytic copper foil side, and thus the adhesiveness of both the electrolytic copper foil side and the aluminum foil side to the sealing resin is improved.

[0011] In the above-mentioned method for producing a bipolar current collector, the sealing resin is preferably an acid-modified polyolefin resin. Effect of the Invention

[0012] According to the present invention, it is possible to improve the adhesion of a bipolar electrode having a bipolar current collector made of rolled aluminum foil and electrolytic copper foil to a sealing resin. [Brief description of the drawings]

[0013] [Figure 1] FIG. 1 is a cross-sectional view of the electricity storage device. [Diagram 2] FIG. 2 is a cross-sectional view of a bipolar electrode. [Diagram 3] FIG. 3 is an explanatory diagram of the lamination step. [Figure 4] FIG. 4 is an explanatory diagram of the first carbon coat forming step. [Diagram 5] FIG. 5 is an explanatory diagram of the second carbon coat forming step. [Figure 6] FIG. 6 is a graph showing the results of analysis by X-ray photoelectron spectroscopy. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. First, the electricity storage device 20 manufactured by the manufacturing method of this embodiment will be described. <Electricity storage device> The power storage device 20 is, for example, a lithium ion secondary battery. The power storage device 20 is, for example, a power storage module used in batteries of various vehicles such as forklifts, hybrid cars, electric cars, etc. The power storage device 20 may be an electric double layer capacitor.

[0015] 1, the electricity storage device 20 includes a laminate 21, a sealing resin 22, and an electrolyte L. The laminate 21 has a plurality of bipolar electrodes 23, a positive terminal electrode 24, a negative terminal electrode 25, and a plurality of separators 26.

[0016] (Bipolar electrode) As shown in FIG. 2, the bipolar electrode 23 includes a bipolar current collector 30, a positive electrode active material layer 31, and a negative electrode active material layer 32.

[0017] [Bipolar current collector] The bipolar current collector 30 is a chemically inactive electrical conductor for continuing to pass current through the positive electrode active material layer 31 and the negative electrode active material layer 32 during discharging or charging of the electricity storage device 20. The bipolar current collector 30 has a first main surface 30a and a second main surface 30b. The first main surface 30a and the second main surface 30b are surfaces perpendicular to the thickness direction of the bipolar current collector 30. The second main surface 30b is located opposite the first main surface 30a in the thickness direction of the bipolar current collector 30. The plan view described below means a view in the thickness direction of the bipolar current collector 30.

[0018] The bipolar current collector 30 is a laminate formed by integrally bonding a sheet-shaped positive electrode current collector 33 and a sheet-shaped negative electrode current collector 34 in the thickness direction. One example of the bipolar current collector 30 has an adhesive layer (not shown) located between the positive electrode current collector 33 and the negative electrode current collector 34 to bond the positive electrode current collector 33 and the negative electrode current collector 34.

[0019] The adhesive layer is conductive and electrically connects the positive electrode collector 33 and the negative electrode collector 34. The adhesive layer includes, for example, an adhesive component and a conductive component dispersed in the adhesive component. Examples of the adhesive component include polyolefin resins such as polypropylene and polyethylene. The adhesive component may be one type or a combination of two or more types. The adhesive component may include a curing agent such as an isocyanate curing agent or an epoxy curing agent. An example of the adhesive component includes a polyolefin resin and an epoxy curing agent. In this case, the generation of gas accompanying the curing reaction can be suppressed. Examples of the conductive component include conductive particles and conductive fillers. Examples of the conductive particles include metal particles such as aluminum particles, nickel particles, SUS particles, silver particles, gold particles, copper particles, titanium particles, and alloy particles, and carbon particles such as graphite particles. The conductive particles may also be spherical particles in which a metal film is formed on the surface of a core particle such as a resin or ceramic. Examples of the conductive filler include carbon nanotubes. The conductive component may be one type or a combination of two or more types. The adhesive component may be an adhesive component having electrical conductivity. An example of an adhesive component having electrical conductivity is a conductive polymer material. When the adhesive component has electrical conductivity, the conductive component dispersed in the adhesive component may be omitted.

[0020] A first main surface 30a of the bipolar current collector 30 is formed by a positive electrode current collector 33. A second main surface 30b of the bipolar current collector 30 is formed by a negative electrode current collector 34. The bipolar current collector 30 has, for example, a rectangular shape in a plan view. Note that in FIG. 1, the bipolar current collector 30 is illustrated in a simplified form.

[0021] The positive electrode current collector 33 is a chemically inactive electrical conductor for continuing to pass a current through the positive electrode active material layer 31 during discharging or charging of the electricity storage device 20. The positive electrode current collector 33 is an aluminum current collector made of rolled aluminum foil. The thickness of the rolled aluminum foil constituting the positive electrode current collector 33 is, for example, 10 μm or more and 200 μm or less.

[0022] The negative electrode current collector 34 is a chemically inactive electrical conductor for continuing to pass a current through the negative electrode active material layer 32 during discharging or charging of the electricity storage device 20. The negative electrode current collector 34 is a copper current collector made of electrolytic copper foil. The thickness of the electrolytic copper foil constituting the negative electrode current collector 34 is, for example, 1 μm or more and 20 μm or less.

[0023] A carbon coating layer C1 is provided on the surface of the positive electrode current collector 33, which is the first main surface 30a of the bipolar current collector 30. The carbon coating layer C1 is provided on the entire first main surface 30a. Therefore, the first main surface 30a is bonded to a sealing resin 22, which will be described later.

[0024] A carbon coating layer C2 is provided on the surface of the negative electrode current collector 34, which is the second main surface 30b of the bipolar current collector 30. The carbon coating layer C2 is provided on the entire second main surface 30b. Therefore, the second main surface 30b is bonded to a sealing resin 22, which will be described later.

[0025] Each of the carbon coating layers C1 and C2 contains carbon particles and a coating layer binder. The carbon particles and the coating layer binder will be described in detail later in the description of the manufacturing method of the bipolar current collector 30.

[0026] The thickness of each of the carbon coating layers C1 and C2 is, for example, not less than 0.1 μm and not more than 5 μm, and preferably not less than 0.5 μm and not more than 2 μm. The weight of each of the carbon coating layers C1 and C2 is, for example, 0.2 g / m 2 More than 1.0g / m 2 The thickness is preferably 0.6 μm or more and 1.8 μm or less.

[0027] The carbon coating layers C1, C2 may all have the same composition, thickness, and basis weight, or one or all of them may be different. [Cathode active material layer] The positive electrode active material layer 31 is provided on the first main surface 30a of the bipolar current collector 30 via the carbon coating layer C1. The positive electrode active material layer 31 includes a positive electrode active material capable of absorbing and releasing charge carriers such as lithium ions. Examples of the positive electrode active material include polyanion compounds such as olivine-type lithium iron phosphate (LiFePO4), lithium composite metal oxides having a layered rock salt structure, and metal oxides having a spinel structure. The positive electrode active material used is one that can be used as a positive electrode active material for a power storage device such as a lithium ion secondary battery.

[0028] The positive electrode active material layer 31 may contain other components such as a conductive assistant for increasing electrical conductivity, a binder, an electrolyte (polymer matrix, ion conductive polymer, liquid electrolyte, etc.), an electrolyte supporting salt for increasing ion conductivity (lithium salt), etc. The types of other components contained in the positive electrode active material layer 31 and the mixing ratio thereof are not particularly limited.

[0029] The positive electrode active material layer 31 has a thickness of, for example, 2 to 150 μm. The positive electrode active material layer 31 has, for example, a rectangular shape in a plan view. The outer shape of the positive electrode active material layer 31 is slightly smaller than the outer shape of the bipolar current collector 30. As shown in FIG. 1, the first main surface 30a of the bipolar current collector 30 includes a first uncoated region 30c. The first uncoated region 30c is a region where the positive electrode active material layer 31 is not provided. The first uncoated region 30c is located in the peripheral portion of the first main surface 30a.

[0030] [Negative electrode active material layer] The negative electrode active material layer 32 is provided on the second main surface 30b of the bipolar current collector 30 via the carbon coating layer C2. The negative electrode active material layer 32 includes a negative electrode active material capable of absorbing and releasing charge carriers such as lithium ions. The negative electrode active material is not particularly limited and may be any simple substance, alloy, or compound capable of absorbing and releasing charge carriers such as lithium ions. For example, the negative electrode active material may be Li, carbon, a metal compound, an element capable of alloying with lithium, or a compound thereof. Examples of carbon include natural graphite, artificial graphite, hard carbon (hardly graphitizable carbon), and soft carbon (easily graphitizable carbon). Examples of artificial graphite include highly oriented graphite and mesocarbon microbeads. Examples of elements capable of alloying with lithium include silicon and tin.

[0031] The negative electrode active material layer 32 may contain other components such as a conductive assistant for enhancing electrical conductivity, a binder, an electrolyte (polymer matrix, ion conductive polymer, liquid electrolyte, etc.), an electrolyte supporting salt for enhancing ion conductivity (lithium salt), etc. The types of other components contained in the negative electrode active material layer 32 and the compounding ratio thereof are not particularly limited.

[0032] The negative electrode active material layer 32 has a thickness of, for example, 2 to 150 μm. The negative electrode active material layer 32 has, for example, a rectangular shape in a plan view. The outer shape of the negative electrode active material layer 32 is slightly smaller than the outer shape of the bipolar current collector 30. As shown in FIG. 1, the second main surface 30b of the bipolar current collector 30 includes a second uncoated region 30d. The second uncoated region 30d is a region where the negative electrode active material layer 32 is not provided. The second uncoated region 30d is located in the peripheral portion of the second main surface 30b.

[0033] (Sealing resin material) The sealing resin 22 is made of an acid-modified polyolefin resin. Examples of the acid-modified polyolefin resin include acid-modified polyethylene, acid-modified polypropylene, acid-modified isoprene, and acid-modified polybutene. Examples of the acid-modified group include a carboxylic acid group, a maleic acid group, and a maleic anhydride group. The acid-modified polyolefin resin constituting the sealing resin 22 may be one type or a combination of two or more types. The acid-modified polyolefin resin constituting the sealing resin 22 may be a thermoplastic resin or a thermosetting resin.

[0034] As shown in FIG. 1, the sealing resin 22 has a plurality of first sealing resins 27 and one second sealing resin 28. The first sealing resin 27 has a rectangular frame shape. The first sealing resin 27 has a first sealing surface 27a and a second sealing surface 27b. The first sealing surface 27a and the second sealing surface 27b are surfaces perpendicular to the thickness direction of the first sealing resin 27. The second sealing surface 27b is located on the opposite side to the first sealing surface 27a in the thickness direction of the first sealing resin 27. The second sealing resin 28 has, for example, a rectangular frame shape.

[0035] (Laminate) The laminate 21 is formed by stacking a plurality of bipolar electrodes 23, a positive terminal electrode 24, a negative terminal electrode 25, and a plurality of separators 26. The direction in which the plurality of bipolar electrodes 23, the positive terminal electrode 24, the negative terminal electrode 25, and the plurality of separators 26 are stacked is defined as the stacking direction.

[0036] The separator 26 is, for example, a porous sheet or nonwoven fabric containing a polymer that absorbs and retains the liquid electrolyte. Examples of materials constituting the separator 26 include polypropylene, polyethylene, polyolefin, and polyester. The separator 26 may have a single-layer structure or a multi-layer structure. The multi-layer structure may include, for example, an adhesive layer, a ceramic layer as a heat-resistant layer, and the like.

[0037] The bipolar electrodes 23 and the separators 26 are alternately stacked between the positive terminal electrode 24 and the negative terminal electrode 25. In two bipolar electrodes 23 adjacent to each other in the stacking direction, the positive electrode active material layer 31 of one bipolar electrode 23 faces the negative electrode active material layer 32 of the other bipolar electrode 23 with the separator 26 sandwiched therebetween.

[0038] The positive terminal electrode 24 includes a sheet-like terminal positive electrode current collector 24a and a terminal positive electrode active material layer 24b provided on one main surface of the terminal positive electrode current collector 24a. For example, the terminal positive electrode current collector 24a may be the one described for the positive electrode current collector 33. The terminal positive electrode active material layer 24b may be the one described for the positive electrode active material layer 31.

[0039] The negative electrode terminal electrode 25 includes a sheet-like terminal negative electrode current collector 25a and a terminal negative electrode active material layer 25b provided on one main surface of the terminal negative electrode current collector 25a. As the terminal negative electrode current collector 25a, the same as described for the negative electrode current collector 34 can be applied. As the terminal negative electrode active material layer 25b, the same as described for the negative electrode active material layer 32 can be applied.

[0040] A first seal resin 27 is disposed between the bipolar current collectors 30 of the two bipolar electrodes 23 adjacent to each other in the stacking direction. The first seal resin 27 surrounds the positive electrode active material layer 31 of one bipolar electrode 23 and the negative electrode active material layer 32 of the other bipolar electrode 23 of the two bipolar electrodes 23 adjacent to each other in the stacking direction. A first seal surface 27a of the first seal resin 27 is welded to a first uncoated region 30c of a first main surface 30a of the bipolar current collector 30. A second seal surface 27b of the first seal resin 27 is welded to a second uncoated region 30d of a second main surface 30b of the bipolar current collector 30. The first seal resin 27 can be welded to the bipolar current collector 30 by a known welding method such as heat welding, ultrasonic welding, or infrared welding.

[0041] A first sealing resin 27 is arranged between the bipolar electrode 23 located at the end on one side of the stacking direction and the positive terminal electrode 24, and between the bipolar electrode 23 located at the end on the other side of the stacking direction and the negative terminal electrode 25, similarly to between adjacent bipolar electrodes 23.

[0042] The second seal resin 28 is disposed so as to surround the laminate 21. The second seal resin 28 has a portion positioned so as to surround a plurality of first seal resins 27, and a portion interposed between the first seal resins 27 adjacent to each other in the stacking direction.

[0043] (electrolyte) The electrolyte L is contained in a space partitioned by the bipolar current collectors 30 of two bipolar electrodes 23 adjacent to each other in the stacking direction and the first seal resin 27 located between these two bipolar current collectors 30. The electrolyte L is also contained in a space partitioned by the bipolar electrode 23, the positive terminal electrode 24, and the first seal resin 27 located therebetween, and in a space partitioned by the bipolar electrode 23, the negative terminal electrode 25, and the first seal resin 27 located therebetween.

[0044] The electrolyte L may be, for example, an electrolyte containing a non-aqueous solvent and an electrolyte salt dissolved in the non-aqueous solvent. The electrolyte salt may be, for example, LiClO4, LiAsF6, LiPF6, LiBF4, LiCF3SO3, LiN(FSO2)2, LiN(CF3SO2)2, or other known lithium salts. The non-aqueous solvent may be, for example, a known solvent such as cyclic carbonates, cyclic esters, chain carbonates, chain esters, or ethers. Two or more of these known solvent materials may be used in combination.

[0045] (Energy storage cell) The power storage device 20 is configured to include a plurality of storage cells 29 stacked in the stacking direction of the laminate 21. The plurality of storage cells 29 are formed of the laminate 21, a sealing resin 22, and an electrolytic solution L. Two storage cells 29 adjacent to each other in the stacking direction share one bipolar electrode 23 and are connected in series via the shared bipolar electrode 23. Thus, the power storage device 20 includes a plurality of storage cells 29 connected in series via the bipolar electrode 23.

[0046] <Method of manufacturing electricity storage device> Next, an example of a method for manufacturing the electricity storage device 20 of this embodiment will be described. The electricity storage device 20 is manufactured by sequentially performing an electrode formation step and an electricity storage cell formation step.

[0047] (Electrode formation process) The electrode forming process includes a bonding process, a winding process, a corona discharge process, a carbon coat layer forming process, and an intermediate winding process. The bipolar current collector 30 is formed by performing each of these processes in order. The corona discharge process includes a first corona discharge process and a second corona discharge process. The carbon coat layer forming process includes a first carbon coat layer forming process and a second carbon coat layer forming process. In this embodiment, the bonding process, the winding process, the first corona discharge process, the first carbon coat layer forming process, the second corona discharge process, and the second carbon coat layer forming process are performed in order.

[0048] As shown in FIG. 3, the lamination step is a step of forming a laminate 40 by laminating a rolled aluminum foil 41 and an electrolytic copper foil 42. The laminate 40 has an aluminum surface 40a formed by the rolled aluminum foil 41 and a copper surface 40b formed by the electrolytic copper foil 42. The laminate 40 is formed, for example, by overlapping and bonding a rolled aluminum foil 41 drawn out from a roll of rolled aluminum foil and an electrolytic copper foil 42 drawn out from a roll of electrolytic copper foil. For example, a method of bonding the rolled aluminum foil 41 and the electrolytic copper foil 42 can be mentioned using a conductive adhesive. As the conductive adhesive, an adhesive that forms the adhesive layer by curing is used. The conductive adhesive is, for example, a solvent-based adhesive containing the adhesive component, the conductive component, and a solvent. Examples of the solvent include organic solvents such as aromatic solvents such as toluene and xylene, aliphatic solvents, alicyclic solvents, ester solvents, ketone solvents, and alcohols. These solvents may be one type or a combination of two or more types.

[0049] The winding process is a process of forming a first roll body by winding the laminate 40 formed in the laminating process into a roll. At this time, the laminate 40 is stacked in a rolled state, so that the rolling oil adhering to the rolled aluminum foil is transferred to the electrolytic copper foil. The effect of the rolling oil transferred to the electrolytic copper foil will be described later.

[0050] The first corona discharge step is a step of performing a corona discharge treatment on the aluminum surface 40a of the laminate 40 unwound from the first roll. A specific method of the first corona discharge step will be described later.

[0051] As shown in Fig. 4, the first carbon coat layer forming step is a step of forming a carbon coat layer C1 on the aluminum surface 40a of the corona discharge treated laminate 40. A specific method of the first corona discharge step will be described later. The first carbon coat layer forming step is performed consecutively after the first corona discharge step. "Consecutively" means that the first corona discharge step and the first carbon coat layer forming step are performed in the unwound state without winding between steps.

[0052] Between the first corona discharge step and the first carbon coat layer forming step, a surface cleaning step may be additionally performed to clean the aluminum surface 40a of the corona discharge-treated laminate 40. An example of the surface cleaning step is a plasma treatment step. Even if the surface cleaning step is performed, it is included in the above-mentioned consecutive steps as long as the first corona discharge step and the first carbon coat layer forming step are performed in the unwound state without winding between the steps.

[0053] The intermediate winding step is a step of forming a second roll body by winding the laminate 40 on which the carbon coating layer C1 has been formed into a roll. The second corona discharge step is a step of performing a corona discharge treatment on the copper surface 40b of the laminate 40 unwound from the second roll. A specific method of the second corona discharge step will be described later.

[0054] As shown in Fig. 5, the second carbon coat layer forming step is a step of forming a carbon coat layer C2 on the copper surface 40b of the corona discharge treated laminate 40. A specific method of the second corona discharge step will be described later. The second carbon coat layer forming step is performed consecutively after the second corona discharge step. "Consecutively" means that the second corona discharge step and the second carbon coat layer forming step are performed in the unwound state without winding between steps.

[0055] Between the second corona discharge step and the second carbon coat layer forming step, a surface cleaning step may be additionally performed to clean the copper surface 40b of the corona discharge-treated laminate 40. An example of the surface cleaning step is a plasma treatment step. Even if the surface cleaning step is performed, it is included in the above-mentioned consecutive steps as long as the second corona discharge step and the second carbon coat layer forming step are performed in the unwound state without winding between the steps.

[0056] The bipolar current collector 30 is formed through the above-mentioned steps. The aluminum surface 40a of the laminate 40 on which the carbon coating layer C1 is formed becomes the first main surface 30a of the bipolar current collector 30, and the copper surface 40b on which the carbon coating layer C2 is formed becomes the second main surface 30b of the bipolar current collector 30. The formed bipolar current collector 30 is wound up into a roll as necessary. In this case, a long bipolar current collector 30 can be continuously manufactured by a roll-to-roll method.

[0057] [Corona discharge treatment] The corona discharge treatment in the first corona discharge step and the second corona discharge step is carried out, for example, by placing the unwound laminate 40 between electrodes and applying a high voltage between the electrodes in normal air pressure to cause discharge. The output intensity is, for example, 0.1 kW or more and 5.0 kW or less. The moving speed of the laminate 40 is, for example, 5 m / min or more and 100 m / min or less. The treatment conditions for the corona discharge treatment are not particularly limited and can be changed as appropriate.

[0058] Furthermore, the first corona discharge step and the second corona discharge step may be performed under the same corona discharge treatment conditions, or may be performed under different corona discharge treatment conditions. [Method of forming carbon coating layer] As a method for forming the carbon coating layer in the first carbon coating layer forming step and the second carbon coating layer forming step, a known method applicable to the formation of a coating film, such as a solution-based process, a vapor deposition-based process, etc. An example of the solution-based process is described below.

[0059] First, carbon particles, a coating layer binder, and an aqueous solvent are mixed together to prepare a carbon paste. A coating film is formed by adhering the carbon paste to a predetermined thickness on the aluminum surface 40a or the copper surface 40b of the laminate 40. The formed coating film is dried and solidified to form a carbon coating layer. Examples of the treatment for solidifying the carbon paste coating include a treatment for drying the coating film to volatilize the solvent, heating the coating film to a temperature equal to or higher than the glass transition temperature of the coating layer binder, and then cooling the coating film to solidify it.

[0060] As the carbon particles, known carbon materials applicable to carbon coating layers such as graphite, acetylene black, etc. can be used. The content of the carbon particles in the solid content contained in the carbon paste is, for example, 13 mass % or more and 90 mass % or less.

[0061] Examples of materials constituting the coating layer binder include acrylic resins and carboxy-modified styrene-butadiene rubber. The material constituting the coating layer binder is preferably an acrylic resin.

[0062] Examples of the acrylic resin include homopolymers of acrylic monomers such as acrylic acid, methacrylic acid, and (meth)acrylic acid esters, and (meth)acrylic copolymers containing the above acrylic monomers. In the present embodiment, (meth)acrylic acid means acrylic acid or methacrylic acid.

[0063] Examples of the (meth)acrylic acid ester include methyl (meth)acrylate, ethyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, and isobutyl (meth)acrylate.

[0064] In the above (meth)acrylic copolymer, other comonomers copolymerized with the acrylic monomer include α-olefin, styrene, α-methylstyrene, vinyltoluene, acrylonitrile, methacrylonitrile, and vinyl acetate. These comonomers can be present in the acrylic resin in the form of random copolymer, graft copolymer, or block copolymer. Examples of the above (meth)acrylic copolymer include silicon-modified acrylic styrene resin, carboxy-modified acrylic styrene resin, and hydroxyl-modified acrylic resin.

[0065] The material constituting the coating layer binder may be one type or a combination of two or more types. The carbon paste may contain other components such as a dispersant, for example, carboxyethyl cellulose.

[0066] Examples of the aqueous solvent used in the carbon paste include water and a mixed solvent of water and an organic solvent. Examples of the organic solvent used in the mixed solvent include N-methyl-2-pyrrolidone (NMP).

[0067] In the first carbon coating layer forming step and the second carbon coating layer forming step, the carbon coating layer may be formed by the same method, or may be formed by different methods.

[0068] [Active material layer formation process] The electrode forming step further includes an active material layer forming step of forming an active material layer on each of a part of the aluminum surface 40a and a part of the copper surface 40b of the laminate 40 after the carbon coat layer forming step. The active material layer forming step is a step of forming a positive electrode active material layer 31 on a part of the first main surface 30a of the bipolar current collector 30, and forming a negative electrode active material layer 32 on a part of the second main surface 30b.

[0069] The laminate 40 provided to the active material layer forming step may be a long sheet, or may be a sheet cut from a long sheet into a predetermined shape. When a long sheet is used, a process of cutting the long sheet on which the active material layer is formed into a predetermined shape is performed after the active material layer forming step. In the following, as an example, a case where the laminate 40 provided to the active material layer forming step is a sheet cut from a long sheet into a predetermined shape will be described.

[0070] The electrode forming step includes a coating step and a drying step. The coating step is a step of coating the electrode mixture on the aluminum surface 40a of the bipolar current collector 30 so as to form a first uncoated region 30c, and coating the electrode mixture on the copper surface 40b so as to form a second uncoated region 30d. Examples of methods for coating the electrode mixture include a roll method, a die coating method, a reverse roll method, a doctor blade method, a knife method, a gravure method, a dip method, and a squeeze method.

[0071] The electrode mixture applied to the aluminum surface 40a is a positive electrode mixture. The positive electrode mixture is a mixture that becomes the positive electrode active material layer 31 by solidification. The positive electrode mixture is, for example, a slurry. The positive electrode mixture contains a positive electrode active material, a binder, and an aqueous solvent, and may contain other components as necessary. The components contained in the positive electrode mixture other than the aqueous solvent are the same as those described in the above section on the positive electrode active material layer.

[0072] The electrode mixture applied to the copper surface 40b is a negative electrode mixture. The negative electrode mixture is a mixture that becomes the negative electrode active material layer 32 by solidification. The negative electrode mixture is, for example, a slurry. The negative electrode mixture contains a negative electrode active material, a binder, and an aqueous solvent, and may contain other components as necessary. The components contained in the negative electrode mixture other than the aqueous solvent are the same as those described in the above section on the negative electrode active material layer.

[0073] The aqueous solvent used in the electrode mixture is water or a mixed solvent of water and an organic solvent. The aqueous solvent is preferably a solvent in which the mass ratio of water is 50 to 100 mass%. The aqueous solvent is mixed into the electrode mixture so that the solid ratio of the electrode mixture is, for example, 60 mass% or more and 80 mass% or less.

[0074] The drying step is a step of removing the aqueous solvent and solidifying the coating layer of the electrode mixture formed on the laminate 40 by drying it. The coating layer solidified through the drying step becomes the positive electrode active material layer 31 and the negative electrode active material layer 32, which are active material layers. Examples of methods for drying the coating layer include natural drying, low-temperature air, hot air, vacuum, infrared rays, far-infrared rays, electron beams, and microwaves. Two or more of these drying methods may be combined. The drying temperature is, for example, 100 degrees or higher and 240 degrees or lower. The drying time is, for example, 10 seconds or higher and 20 hours or lower.

[0075] In the electrode formation step, the order in which the positive electrode active material layer 31 and the negative electrode active material layer 32 are formed may be arbitrary. For example, after the coating step of coating the positive electrode composite and the negative electrode composite, a drying step of drying the coating layer of the positive electrode composite and the coating layer of the negative electrode composite may be performed. Alternatively, the coating step of coating the positive electrode composite and the drying step of drying the coating layer of the positive electrode composite may be performed first, and then the coating step of coating the negative electrode composite and the drying step of drying the coating layer of the negative electrode composite may be performed later.

[0076] Furthermore, in order to increase the electrode density, a compression step may be performed after the drying step to compress the positive electrode active material layer 31 and the negative electrode active material layer 32. Examples of a compression method in the compression step include a die pressing method and a calendar pressing method. The compression step may be performed on only one of the positive electrode active material layer 31 and the negative electrode active material layer 32.

[0077] (Storage cell formation process) In the storage cell formation process, first, a plurality of bipolar electrodes 23, positive electrode terminal electrodes 24, and negative electrode terminal electrodes 25 are arranged so that the positive electrode active material layers 31 and the negative electrode active material layers 32 face each other in the stacking direction with the separator 26 sandwiched therebetween. Then, sealing resin 22 is arranged between the bipolar electrodes 23, between the bipolar electrodes 23 and the positive electrode terminal electrode 24, and between the bipolar electrodes 23 and the negative electrode terminal electrode 25.

[0078] At this time, the sealing resin 22 is arranged so that at least a part of it contacts the portion where the carbon coating layer C1 is formed in the first uncoated region 30c of the first main surface 30a of the bipolar current collector 30 constituting the bipolar electrode 23. In other words, the sealing resin 22 is arranged so as to contact the portion of the aluminum surface 40a of the laminate 40 which is the bipolar current collector 30 where the positive electrode active material layer 31 is not formed and where the carbon coating layer C1 is formed.

[0079] Moreover, the sealing resin 22 is arranged so that at least a part of it contacts the portion where the carbon coating layer C2 is formed in the second uncoated region 30d of the second main surface 30b of the bipolar current collector 30 constituting the bipolar electrode 23. In other words, the sealing resin 22 is arranged so as to contact the portion of the copper surface 40b of the laminate 40 which is the bipolar current collector 30 where the negative electrode active material layer 32 is not formed and where the carbon coating layer C2 is formed.

[0080] Thereafter, the bipolar electrode 23, the positive terminal electrode 24, and the negative terminal electrode 25 are bonded to the sealing resin 22 by welding to form an assembly in which they are integrated. The bonding process when forming the assembly corresponds to a bonding step of bonding the sealing resin 22 to the bipolar electrode 23. The bonding step is a step of bonding the sealing resin 22 to a portion of the copper surface 40b of the laminate 40, which is the bipolar current collector 30, where the active material layer (negative active material layer 32) is not formed and where the carbon coat layer C2 is formed.

[0081] Next, a liquid electrolyte is injected into the sealed space inside the assembly through an injection port provided in a part of the sealing resin 22, and then the injection port is sealed. This forms an electricity storage device 20 including a plurality of electricity storage cells 29 connected in series via bipolar electrodes 23.

[0082] <effect> Next, the operation of this embodiment will be described. First, the cause of the decrease in adhesion to the sealing resin of the bipolar electrode 23 having a bipolar current collector made of rolled aluminum foil and electrolytic copper foil will be described. In order to clarify the cause, the following test was performed.

[0083] By carrying out the following "Step 1"-"Step 2A" in order, the state in which the rolling oil adhering to the rolled aluminum foil is transferred to the electrolytic copper foil in the winding process after the lamination process in the manufacturing process of the electricity storage device was reproduced. In addition, by carrying out the following "Step 1"-"Step 2B"-"Step 3"-"Step 4" in order, the electrolytic copper foil was given a temperature history simulating the manufacturing process of the bipolar current collector and the manufacturing process of the bipolar electrode. Step 2B and Step 3 simulate the lamination process and the carbon coat layer formation process in manufacturing the bipolar current collector. Step 4 simulates the electrode formation process in manufacturing the bipolar electrode.

[0084] Step 1: Prepare electrolytic copper foil (thickness 8 μm). Step 2A: A rolled aluminum foil was placed on the specific surface of the electrolytic copper foil prepared in step 1, and the rolling oil adhering to the rolled aluminum foil was transferred to the specific surface of the electrolytic copper foil, and then the rolled aluminum foil was peeled off from the electrolytic copper foil.

[0085] Step 2B: Heat the electrolytic copper foil prepared in step 1 at 70°C for 3 days, then return it to room temperature. Step 3: After step 2B, the electrolytic copper foil is heated at 100°C for 40 seconds, at 120°C for 40 seconds, and at 150°C for 20 seconds, in that order. Then, it is returned to room temperature.

[0086] Step 4: Heat the electrolytic copper foil after step 3 at 100°C for 8 hours, then return it to room temperature. After each of the above steps, the surface of the electrolytic copper foil was subjected to measurement of wettability, measurement of adhesive strength of the electrolytic copper foil to the sealing resin, and analysis of the surface structure.

[0087] (Measurement of wettability) A 4 μL drop of water was dropped onto the surface of the electrolytic copper foil using a dropper, and the contact angle of the drop of water formed on the surface of the electrolytic copper foil was measured. The results are shown in Table 1.

[0088] (Adhesive strength measurement) From the electrolytic copper foil after each step, a rectangular sheet material of 10 mm length x 50 mm width was cut out. A rectangular sealing material of 10 mm length x 50 mm width was also prepared. An acid-modified polyethylene sheet having a thickness of 120 μm and a melting point of 120° C. was used as the sealing material. The sealing material was laminated on the sheet material so that the ends were aligned to obtain a laminate. The laminate was heated at 150° C. for 10 seconds using an impulse sealer, and then cooled to prepare a measurement sample in which the sheet material and the sealing material were bonded. A 180-degree peel test was performed on the obtained measurement sample under conditions of a pulling speed of 10 mm / min and a temperature of 25° C. The strength measured in the 180-degree peel test was divided by the line width of 10 mm to calculate the peel strength of the measurement sample, and the calculated value was taken as the adhesive strength. The results are shown in Table 1.

[0089] (surface structure analysis) The surface structure of the electrodeposited copper foil after each step was analyzed by X-ray photoelectron spectroscopy, and the results are shown in Figure 6.

[0090] [Table 1] As shown in Table 1, an increase in the contact angle on the surface of the electrolytic copper foil and a decrease in adhesive strength can be confirmed in step 2A. Referring to Fig. 6, the peak shape in step 2A is the same as that in step 1, so the surface structure does not change in step 2A. Therefore, the decrease in adhesive strength in step 2A is considered to be caused by a part of the hydrophilic functional groups such as hydroxyl groups present on the surface of the electrolytic copper foil being covered by the rolling oil transferred from the rolled aluminum foil.

[0091] In addition, as shown in Table 1, a significant increase in the contact angle on the surface of the electrolytic copper foil and a significant decrease in the adhesive strength can be confirmed in step 4. Referring to FIG. 6, the peak shape in step 4 is significantly changed from that in step 1. Specifically, the peak of "Cu" is decreased, and the peak of the oxide "CuO" is increased. Therefore, the decrease in adhesive strength in step 4 is considered to be caused by the surface of the electrolytic copper foil being oxidized by exposure to a high-temperature environment for a long period of time, resulting in a decrease in hydrophilic functional groups such as hydroxyl groups.

[0092] As described above, in a bipolar collector made of rolled aluminum foil and electrolytic copper foil, the cause of the decrease in adhesion to the sealing resin is the rolling oil adhering to the rolled aluminum foil and heating during the electrode formation process.

[0093] In the manufacturing method of the electricity storage device 20 of this embodiment, in the electrode formation step, the laminate 40 in which the rolled aluminum foil and the electrolytic copper foil are bonded together is once wound into a roll to form a roll body, and then a corona discharge treatment is performed on the copper surface 40b of the laminate 40 unwound from the roll body. In this case, the rolling oil that was transferred from the rolled aluminum foil to the electrolytic copper foil when wound into a roll or due to other factors and adhered to the surface of the electrolytic copper foil (the copper surface 40b of the laminate 40) is removed by the corona discharge treatment. As a result, a decrease in the adhesive strength of the sealing resin caused by the rolling oil adhered to the copper surface 40b is suppressed.

[0094] In addition, in the manufacturing method of the electricity storage device 20 of this embodiment, after the corona discharge step, a carbon coating layer C2 is formed on the copper surface 40b of the laminate 40. As a result, the copper surface 40b is covered with the carbon coating layer C2, and the electrolytic copper foil and the carbon coating layer C2 are bonded to each other. This bond is either one or both of an ester bond and a hydrogen bond.

[0095] The ester bond is a bond structure (-COOCu) in which a hydroxyl group (Cu-OH) bonded to a copper atom constituting the electrolytic copper foil and a carboxyl group (-COOH) of the coating layer binder are ester-bonded. The hydrogen bond is a bond structure in which a hydroxyl group (Cu-OH) bonded to a copper atom constituting the electrolytic copper foil and either or both of a hydroxyl group and a carboxyl group of a material constituting the carbon coating layer C2 are hydrogen-bonded. The hydroxyl group is either or both of a hydroxyl group (C-OH) on the surface of the carbon particle and a hydroxyl group (C-OH) of the coating layer binder. The carboxyl group is a carboxyl group (-COOH) of the coating layer binder.

[0096] In particular, the corona discharge treatment has the effect of newly generating hydrophilic functional groups such as hydroxyl groups on the copper surface 40b before the carbon coating layer C2 is formed, i.e., on the surface of the electrolytic copper foil. Therefore, on the copper surface 40b after the corona discharge treatment, many hydrophilic functional groups are formed, and the electrolytic copper foil and the carbon coating layer C2 are firmly bonded to each other. Therefore, the corona discharge treatment also has the effect of strengthening the bond between the electrolytic copper foil and the carbon coating layer C2 in the subsequent carbon coating layer formation step.

[0097] The copper surface 40b is formed in a state in which the hydrophilic functional groups of the electrolytic copper foil are bonded to the carbon coating layer C2, and thus oxidation of the electrolytic copper foil caused by long-term exposure to a high-temperature environment in the electrode formation process is suppressed. The hydroxyl and carboxyl groups of the substances contained in the carbon coating layer C2 are retained without being oxidized even after the electrode formation process, compared with the hydrophilic functional groups of the electrolytic copper foil, and therefore it is possible to bond the carbon coating layer C2 to the sealing resin 22. As a result, the adhesive strength to the sealing resin 22 can be increased compared with the case in which the sealing resin 22 is bonded to the copper surface 40b on which the carbon coating layer C2 is not formed.

[0098] <Effects> According to this embodiment, the following effects can be obtained. (1) The manufacturing method of the electricity storage device 20 includes an electrode forming step of forming the bipolar electrode 23, and an adhesion step of adhering the seal resin 22 to the bipolar electrode 23. The electrode forming step includes a bonding step, a winding step, a corona discharge step, a carbon coat layer forming step, and an active material layer forming step. The bonding step is a step of bonding a rolled aluminum foil 41 and an electrolytic copper foil 42 together to form a laminate 40 having an aluminum surface 40a formed by the rolled aluminum foil 41 and a copper surface 40b formed by the electrolytic copper foil 42. The winding step is a step of winding the laminate 40 into a roll to form a roll body. The corona discharge step is a step of performing a corona discharge treatment on the copper surface 40b of the laminate 40 unwound from the roll body. The carbon coat layer forming step is a step of forming a carbon coat layer C2 on the copper surface 40b after the corona discharge step. In the bonding step, the sealing resin 22 is bonded to the portion of the copper surface 40b where the negative electrode active material layer 32 is not formed and where the carbon coating layer C2 is formed.

[0099] According to the above-mentioned configuration, the rolling oil transferred to the electrolytic copper foil 42 in the winding process is removed by the corona discharge treatment, so that the decrease in adhesive strength of the copper surface 40b caused by the rolling oil can be suppressed. Furthermore, since the copper surface 40b is provided with the carbon coating layer C2, the surface of the carbon coating layer C2 can ensure adhesiveness to the sealing resin 22 even after being exposed to a high-temperature environment for a long period of time in the electrode formation process. Therefore, for the bipolar electrode 23 including the bipolar current collector 30 made of the rolled aluminum foil and the electrolytic copper foil, the adhesiveness of the copper surface 40b (first main surface 30a) to the sealing resin 22 is improved.

[0100] (2) The corona discharge step and the carbon coating layer forming step are carried out successively. When the time between the corona discharge step and the carbon coat layer forming step is long, such as when the laminate 40 after the corona discharge step is wound up and stored, the hydrophilic functional groups generated in the corona discharge step are oxidized and gradually decreased. By continuously performing the carbon coat layer forming step after the corona discharge step, the decrease in the hydrophilic functional groups generated in the corona discharge step can be suppressed. As a result, the carbon coat layer can be firmly bonded to the laminate 40.

[0101] (3) A corona discharge step and a carbon coating layer forming step are performed on both the aluminum surface 40a and the copper surface 40b of the laminate 40. According to the above configuration, the aluminum surface 40a of the laminate 40 (the first main surface 30a of the bipolar current collector 30) can also suppress a decrease in adhesive strength caused by rolling oil and a decrease in adhesive strength caused by long-term exposure to a high-temperature environment, similar to the copper surface 40b of the laminate 40. Therefore, the adhesion to the sealing resin 22 is improved on both the copper surface 40b and the aluminum surface 40a of the laminate 40 (both the second main surface 30b and the first main surface 30a of the bipolar current collector 30).

[0102] This embodiment can be modified as follows: This embodiment and the following modifications can be combined with each other to the extent that no technical contradiction occurs. Regarding the second corona discharge step, the area where the corona discharge treatment is performed is not limited to the entire copper surface 40b of the laminate 40, but may be an area including the portion of the copper surface 40b to which the sealing resin 22 is bonded. Similarly, regarding the first corona discharge step, the area where the corona discharge treatment is performed is not limited to the entire aluminum surface 40a of the laminate 40, but may be an area including the portion of the aluminum surface 40a to which the sealing resin 22 is bonded.

[0103] Regarding the second carbon coating layer forming step, the area where the carbon coating layer C2 is formed is not limited to the entire copper surface 40b of the laminate 40, but may be any area including the portion of the copper surface 40b to which the sealing resin 22 is bonded. Similarly, regarding the first carbon coating layer forming step, the area where the carbon coating layer C1 is formed is not limited to the entire aluminum surface 40a of the laminate 40, but may be any area including the portion of the aluminum surface 40a to which the sealing resin 22 is bonded.

[0104] The order of the first corona discharge step, the second corona discharge step, the first carbon coat layer forming step, and the second carbon coat layer forming step may be changed. For example, the first corona discharge step and the second corona discharge step may be performed after the first corona discharge step and the second carbon coat layer forming step. In this case, the first corona discharge step and the second corona discharge step may be performed simultaneously or separately. Furthermore, the first carbon coat layer forming step and the second carbon coat layer forming step may be performed simultaneously or separately.

[0105] Either or both of the first corona discharge step and the second carbon coating layer forming step may be omitted. In other words, the corona discharge step may be a step of performing a corona discharge treatment on at least the copper surface 40b of the laminate 40. Similarly, the carbon coating layer forming step may be a step of forming a carbon coating layer C2 on at least the copper surface 40b of the laminate 40.

[0106] Next, the technical ideas that can be understood from the above embodiment and modified examples will be described below. [Aspect 1] A method for manufacturing an electricity storage device including a bipolar electrode and a sealing resin bonded to the bipolar electrode, an electrode forming step of forming the bipolar electrode; and a bonding step of bonding the sealing resin to the bipolar electrode, The electrode forming step includes: A lamination step of laminating a rolled aluminum foil and an electrolytic copper foil to form a laminate having an aluminum surface formed by the rolled aluminum foil and a copper surface formed by the electrolytic copper foil; a winding step of winding the laminate into a roll to form a roll body; a corona discharge step of subjecting the copper surface of the laminate unwound from the roll to a corona discharge treatment; a carbon coating layer forming step of forming a carbon coating layer on the copper surface after the corona discharge step; and forming an active material layer on each of the part of the aluminum surface and the part of the copper surface after the carbon coat layer forming step, The method for manufacturing an electricity storage device, wherein the bonding step comprises bonding the sealing resin to a portion of the copper surface on which the active material layer is not formed and on which the carbon coating layer is formed.

[0107] [Aspect 2] 2. The method for producing an electricity storage device according to aspect 1, wherein the corona discharge step and the carbon coat layer forming step are carried out continuously.

[0108] [Aspect 3] 3. The method for producing an electricity storage device according to aspect 1 or 2, wherein the corona discharge step and the carbon coat layer forming step are performed on both the aluminum surface and the copper surface of the laminate.

[0109] [Aspect 4] 5. The method for producing an electricity storage device according to aspect 4, wherein the sealing resin is an acid-modified polyolefin resin.

[0110] [Aspect 5] The bipolar electrode is a bipolar current collector in which an aluminum current collector made of the rolled aluminum foil and a copper current collector made of the electrolytic copper foil are laminated; a positive electrode active material layer provided on a surface of the aluminum current collector of the bipolar current collector; A method for producing an electricity storage device according to any one of aspects 1 to 4, further comprising: a negative electrode active material layer provided on a surface of the copper current collector of the bipolar current collector.

[0111] [Aspect 6] The power storage device is A plurality of the bipolar electrodes arranged such that the positive electrode active material layer and the negative electrode active material layer face each other; a separator disposed between the bipolar electrodes adjacent to each other in the stacking direction; a sealing resin disposed between the bipolar electrodes adjacent in the stacking direction so as to surround the positive electrode active material layer and the negative electrode active material layer, and adhered to the bipolar current collector to form an enclosed space for containing a liquid electrolyte between the bipolar electrodes. [Explanation of symbols]

[0112] C1, C2: Carbon coating layer 20...Electricity storage device 22…Sealing resin 23...Bipolar electrode 30…Bipolar current collector 31...Cathode active material layer 32...Negative electrode active material layer 40...Laminate 40a…Aluminum surface 40b…Copper surface 41...Rolled aluminum foil 42...Electrolytic copper foil

Claims

1. A method for manufacturing an electricity storage device including a bipolar electrode and a sealing resin bonded to the bipolar electrode, an electrode forming step of forming the bipolar electrode; and a bonding step of bonding the sealing resin to the bipolar electrode, The electrode forming step includes: A lamination step of laminating a rolled aluminum foil and an electrolytic copper foil to form a laminate having an aluminum surface formed by the rolled aluminum foil and a copper surface formed by the electrolytic copper foil; a winding step of winding the laminate into a roll to form a roll body; a corona discharge step of subjecting the copper surface of the laminate unwound from the roll to a corona discharge treatment; a carbon coating layer forming step of forming a carbon coating layer on the copper surface after the corona discharge step; and forming an active material layer on each of the part of the aluminum surface and the part of the copper surface after the carbon coat layer forming step, The method for manufacturing an electricity storage device, wherein the bonding step comprises bonding the sealing resin to a portion of the copper surface on which the active material layer is not formed and on which the carbon coating layer is formed.

2. The method for producing an electricity storage device according to claim 1 , wherein the corona discharge step and the carbon coat layer forming step are carried out continuously.

3. The method for producing an electricity storage device according to claim 1 , wherein the corona discharge step and the carbon coat layer forming step are performed on both the aluminum surface and the copper surface of the laminate.

4. The method for producing an electricity storage device according to any one of claims 1 to 3, wherein the sealing resin is an acid-modified polyolefin resin.

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