Manufacturing method for current collector foil

Abstract

To provide a manufacturing method for a current collector foil whereby generation of pinholes can be reduced.SOLUTION: A manufacturing method for a current collector foil, includes: a first step of applying an adhesive to one surface of a first metal foil; a second step of bonding a second metal foil to the surface of the first metal foil to which the adhesive has been applied, and applying heat and pressure thereto to obtain a bonded foil; and a third step of winding the bonded foil; wherein the surface tension of the adhesive agent is 60 mN / m or less, and a contact angle between the adhesive agent and the first metal foil is 60° or less.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present disclosure relates to a method for manufacturing a current collector foil. [Background technology]

[0002] Various techniques have been proposed for manufacturing current collector foils as disclosed in Patent Documents 1 and 2. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. H08-007926 [Patent Document 2] JP 2023-053669 A Summary of the Invention [Problem to be solved by the invention]

[0004] The current collector foil used in bipolar batteries is, for example, a clad material in which aluminum (Al) foil and copper (Cu) foil are bonded together. It is known that the current collector foil is manufactured by rolling aluminum foil and copper foil. From the viewpoint of improving the battery capacity, it is preferable that this current collector foil is thin. If the current collector foil is made thin, pinholes may occur in the current collector foil. If pinholes exist, they may become larger during charging and discharging. As a method for solving the above problems, for example, Patent Document 2 proposes a current collector foil having an anodized aluminum layer with Ni portions formed in pores between Al-Cu. However, the anodizing process is costly. In addition, this technology has problems such as the anodized aluminum layer being formed on the Al foil, so that if there are pinholes in the Al foil, the anodized aluminum layer is not formed in the pinholes in the Al foil.

[0005] The present disclosure has been made in consideration of the above-mentioned circumstances, and has as its main object to provide a manufacturing method for a current collector foil that can reduce the occurrence of pinholes. [Means for solving the problem]

[0006] That is, the present disclosure includes the following aspects. <1> A first step of applying an adhesive to one side of a first metal foil; A second step of laminating a second metal foil to the surface of the first metal foil to which the adhesive is applied, and then heating and pressing the second metal foil to obtain a laminated foil; A third step of winding up the laminated foil, The adhesive has a surface tension of 60 mN / m or less; The method for producing a current collector foil, wherein a contact angle between the adhesive and the first metal foil is 60° or less.

[0007] <2> the adhesive comprises a leveling agent; The content of the leveling agent is 0.1% by mass or more and 1% by mass or less with respect to the total mass of the adhesive. <1> A method for producing the current collector foil according to claim 1.

[0008] <3> The adhesive contains water as a solvent. <1> or the above <2> A method for producing the current collector foil according to claim 1.

[0009] <4> The first metal foil is an aluminum foil. <1> ~The above <3> 13. A method for producing a current collector foil according to claim 12.

[0010] <5> The above <1> ~The above <4> 13. A method for producing a battery using a current collecting foil obtained by the method according to claim 12. Effect of the Invention

[0011] The method for producing a current collector foil according to the present disclosure can reduce the occurrence of pinholes. [Brief description of the drawings]

[0012] [Figure 1] FIG. 1 is a flowchart of the first embodiment. [Diagram 2]FIG. 2 is a schematic diagram showing an example of a bonding apparatus (dry lamination). [Diagram 3] FIG. 3 is a flowchart of the first comparative example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Hereinafter, embodiments of the present disclosure will be described. Note that matters other than those specifically mentioned in this specification and necessary for implementing the present disclosure (for example, the general configuration and manufacturing process of the current collector foil that do not characterize the present disclosure) can be understood as design matters of a person skilled in the art based on the prior art in the field. The present disclosure can be implemented based on the contents disclosed in this specification and the technical common sense in the field. Furthermore, the dimensional relationships (length, width, thickness, etc.) in the drawings do not reflect the actual dimensional relationships.

[0014] In the present disclosure, a first step includes applying an adhesive to one side of a first metal foil; A second step of laminating a second metal foil to the surface of the first metal foil to which the adhesive is applied, and then heating and pressing the second metal foil to obtain a laminated foil; A third step of winding up the laminated foil, The adhesive has a surface tension of 60 mN / m or less; The method for producing a current collector foil is provided, wherein a contact angle between the adhesive and the first metal foil is 60° or less.

[0015] In the present disclosure, a laminated foil is produced by laminating a first metal foil and a second metal foil together using a dry laminator.

[0016] The method for producing a current collector foil according to the present disclosure includes a first step, a second step, and a third step.

[0017] (1st step) The first step is to apply an adhesive to one side of a first metal foil. The method of applying the adhesive is not particularly limited, and for example, the first metal foil in a roll form may be unwound and the adhesive may be applied using a doctor blade, a gravure roll, or the like. Thereafter, the solvent in the adhesive may be dried using hot air or the like in a drying oven. The temperature of the drying oven may be, for example, 150° C. or higher.

[0018] The surface tension of the adhesive is 60 mN / m or less. The contact angle between the adhesive and the first metal foil is 60° or less. The base material of the adhesive is preferably a water-based polyester resin solution. Here, the water-based polyester resin solution refers to a solution containing water as a solvent and a polyester resin as a solute. Examples of the aqueous polyester resin solution include Aronmelt (Aronmelt is a registered trademark) PES1000 and Aronmelt PES2000 series manufactured by Toagosei Co., Ltd. The content of the base agent may be 50% by mass or more based on the total mass of the adhesive. The adhesive may contain a conductive additive, which may be Ni-plated particles or the like. The content of the conductive assistant is not particularly limited. The adhesive may contain a leveling agent. Here, the leveling agent refers to a compound that, when added to an adhesive, lowers the surface tension of the adhesive compared to before the addition. The addition of a leveling agent lowers the surface tension of the adhesive, making it easier for the adhesive to penetrate into pinholes in the first metal foil. Therefore, even if pinholes exist in the first metal foil, the pinholes can be filled with the adhesive, preventing the liquid from penetrating into the current collecting foil. The content of the leveling agent may be 0.1 mass % or more and 1 mass % or less with respect to the total mass of the adhesive. The leveling agent may be a hydrocarbon resin, a silicone resin, a fluorine resin, or the like, and may be BYK-ET 3033 (BYK is a registered trademark) manufactured by BYK. The adhesive may contain water as a solvent.

[0019] Examples of metals that can be used for the first metal foil include aluminum, copper, SUS, and nickel. The first metal foil may be an aluminum foil. The thickness of the first metal foil is, for example, not less than 0.1 μm and not more than 100 μm.

[0020] (2nd process) The second step is a step of laminating a second metal foil onto the surface of the first metal foil on which the adhesive has been applied, and then heating and pressing the resulting laminated foil.

[0021] The method of heating and pressing in the second step is not particularly limited, and for example, a workpiece in which a roll of a second metal foil is unrolled and bonded onto the surface of a first metal foil to which an adhesive has been applied may be heated and pressed using a heat roll, a rubber roll, or the like. The hot roll temperature may be, for example, 90° C. or higher. The hot roll nip pressure may be, for example, 0.45 MPa or more.

[0022] The metal used for the second metal foil may be different from the metal used for the first metal foil. Metals that can be used for the second metal foil include copper, SUS, nickel, and the like. For example, aluminum may be selected as the metal for the first metal foil, and copper may be selected as the metal for the second metal foil. The second metal foil may be a copper foil. The thickness of the second metal foil is, for example, not less than 0.1 μm and not more than 100 μm.

[0023] (3rd step) The third step is a step of winding up the laminated foil. The method for winding the laminated foil is not particularly limited, and the laminated foil obtained in the second step may be wound up using a roller, etc. After the laminated foil is wound up, the laminated foil in the roll state may be heated. The winding line speed may be, for example, 15 m / min or more.

[0024] The current collector foil obtained by the manufacturing method of the present disclosure comprises a laminated foil in which a first metal foil and a second metal foil are laminated with an adhesive. The current collector foil may be a bipolar current collector foil. A bipolar current collector foil is a current collector foil having a positive electrode current collector foil on one side and a negative electrode current collector foil on the other side. It is preferable that the first metal foil is a positive electrode current collector foil and the second metal foil is a negative electrode current collector foil. The thickness of the current collecting foil is, for example, not less than 0.2 μm and not more than 200 μm.

[0025] The present disclosure provides a method for producing a battery that uses a current collector foil obtained by the method for producing a current collector foil. The current collector foil of the present disclosure is used in the manufacture of batteries. The type of battery in which the current collecting foil is used is not particularly limited, and may be, for example, a lithium ion secondary battery. The battery may be a liquid battery using an electrolytic solution as an electrolyte, or a solid battery using a solid electrolyte as an electrolyte. Applications of the battery include, for example, power sources for vehicles such as hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), electric vehicles (BEVs), gasoline automobiles, and diesel automobiles. In particular, the battery may be used as a driving power source for hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), or electric vehicles (BEVs). The battery may also be used as a power source for moving objects other than vehicles (for example, railways, ships, and aircraft), and may be used as a power source for electrical appliances such as information processing devices. EXAMPLES

[0026] Example 1 An aluminum foil was used as the first metal foil, and a copper foil was used as the second metal foil. The adhesive used was a water-based polyester resin solution (manufactured by Toa Gosei Co., Ltd.) as a base agent, Ni-plated particles as a conductive assistant, and BYK-ET 3033 (manufactured by BYK Co., Ltd.) as a leveling agent. The amount of the leveling agent added was 0.1% by mass or more and 1% by mass or less of the total mass of the adhesive. The surface tension of the adhesive was 30 mN / m or more and 60 mN / m or less, and the contact angle with the aluminum foil was 60°. FIG. 1 is a flowchart of the first embodiment. FIG. 2 is a schematic diagram showing an example of a bonding apparatus (dry lamination). The dry lamination conditions shown in FIG. 2 were set as follows: Line speed: 15m / min Gravure roll: Elongated, 75 lines ·Drying oven temperature: 150℃ Heat roll temperature: 90℃ Heat roll nip pressure: 0.45MPa In Example 1, as shown in FIG. 1, a mixture of a main agent, a conductive additive, and a leveling agent was used as the adhesive. As shown in FIG. 2, in the first step, a first metal foil 1 was unrolled, and an adhesive 2 was applied to one side of the first metal foil 1 with a gravure roll 3 to impregnate the adhesive into pinholes present in the first metal foil 1. The solvent in the adhesive 2 was then dried in a drying furnace 4. In the second step, a second metal foil 5 was unrolled and placed on the side of the first metal foil 1 on which the adhesive 2 was applied, and these were bonded together while being heated and pressurized by a hot roll 6. In the third step, the laminated foil 7 was rolled up to obtain a current collector foil.

[0027] Comparative Example 1 FIG. 3 is a flowchart of the first comparative example. In Comparative Example 1, as shown in FIG. 3, a current collector foil was obtained in the same manner as in Example 1, except that no leveling agent was used as the adhesive. The surface tension of the adhesive in Comparative Example 1 was 72.8 mN / m, and the contact angle with respect to the aluminum foil was 102.3°.

[0028] The current collecting foils produced in Example 1 and Comparative Example 1 were evaluated for the presence or absence of pinholes of 0.5 mm or less. The results are shown in Table 1. Since the pinholes in the current collecting foil are considered to be capillaries, they are considered to be filled by the rise in the liquid level due to capillary action (h) in Equation 1 below. If the value of the rise in the liquid level due to capillary action (h) is positive, capillary action is caused, and the adhesive will easily penetrate into the pinholes in the first metal foil and second metal foil, and the current collecting foil was evaluated as being free of pinholes. Equation 1: h = (2T cosθ) / (ρgr) h: Height of liquid level rise due to capillary action T: Surface tension of adhesive θ: Contact angle between the adhesive and the first metal foil ρ: Density of adhesive (1000kg / m 3 ) g: Gravitational acceleration (9.8m / s 2 ) r: pinhole radius

[0029] [Table 1]

[0030] As shown in Table 1, it has been demonstrated that the current collecting foil obtained by the manufacturing method of the present disclosure can reduce the occurrence of pinholes. [Explanation of symbols]

[0031] 1. First metal foil 2. Glue 3. Gravure roll 4.Drying oven 5. Second metal foil 6. Heat roll 7. Laminated foil

Claims

1. A first step of applying an adhesive to one side of a first metal foil; A second step of laminating a second metal foil onto the surface of the first metal foil on which the adhesive is applied, and then heating and pressing the second metal foil to obtain a laminated foil; A third step of winding up the laminated foil, The adhesive has a surface tension of 60 mN / m or less; The method for producing a current collector foil, wherein a contact angle between the adhesive and the first metal foil is 60° or less.

2. the adhesive comprises a leveling agent; The method for producing a current collector foil according to claim 1 , wherein a content of the leveling agent is 0.1 mass % or more and 1 mass % or less with respect to a total mass of the adhesive.

3. The method for producing a current collector foil according to claim 1 , wherein the adhesive contains water as a solvent.

4. The method for producing a current collector foil according to claim 3 , wherein the first metal foil is an aluminum foil.

5. A method for producing a battery using a current collecting foil obtained by the method according to any one of claims 1 to 4.

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