Electrode structure

Abstract

To provide a technique for preventing an electrode active material from coming into contact with a metal foil and for hardly causing peeling of the electrode active material from a resin layer.SOLUTION: An electrode structure includes a metal foil, a resin layer disposed on the metal foil, and an electrode layer disposed on the resin layer. The resin layer includes a first layer disposed on the metal foil and a second layer disposed on the first layer. The electrode layer comprises a solvent mixed with an electrode active material. The first layer comprises a first resin. The second layer comprises a second resin different from the first resin. A difference between the solubility parameter of the first resin and the solubility parameter of the solvent is greater than a difference between the solubility parameter of the second resin and the solubility parameter of the solvent.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The technology disclosed in this specification relates to an electrode structure, and more particularly to an electrode structure that is a semi-finished product of a battery. [Background technology]

[0002] Various improvements have been made to batteries to improve their performance. For example, the battery disclosed in Patent Document 1 includes a metal foil, a resin layer disposed on the metal foil, and an electrode active material disposed on the resin layer. When manufacturing a battery, an electrode structure is formed, which is a semi-finished product of the battery. The electrode structure includes a metal foil, a resin layer disposed on the metal foil, and an electrode layer disposed on the resin layer. The electrode layer is composed of a solvent mixed with the electrode active material. A battery is formed by removing (drying) the solvent in the electrode layer from the electrode structure. In the electrode structure, the resin constituting the resin layer and the solvent constituting the electrode layer dissolve, causing the electrode active material to penetrate into the resin layer. By having the electrode active material penetrate into the resin layer, the electrode active material is less likely to peel off from the resin layer in a battery from which the solvent has been removed. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-26192 Summary of the Invention [Problem to be solved by the invention]

[0004] In a battery such as that described in Patent Document 1, the electrode active material penetrates into the resin layer as a result of dissolution of the resin constituting the resin layer and the solvent constituting the electrode layer in the electrode structure, which is a semi-finished product of the battery. However, if the resin and solvent are a combination that is easily soluble, the electrode active material may penetrate into the vicinity of the metal foil along with the solvent. If the electrode active material penetrates into the metal foil, the metal foil may be damaged. If the metal foil is damaged and penetrated, the electrode active material may come into contact with the electrode arranged on the opposite side, causing a short circuit. Furthermore, if the resin and solvent are combined in a way that makes them difficult to dissolve in order to prevent the electrode active material from coming into contact with the metal foil, the electrode active material will be less likely to penetrate into the resin, and in a battery from which the solvent has been removed, the electrode active material will be more likely to peel off from the resin layer.

[0005] This specification discloses a technique for preventing the electrode active material from coming into contact with the metal foil and for making the electrode active material less likely to peel off from the resin layer. [Means for solving the problem]

[0006] In a first aspect of the present technology, an electrode structure includes a metal foil, a resin layer disposed on the metal foil, and an electrode layer disposed on the resin layer. The resin layer includes a first layer disposed on the metal foil and a second layer disposed on the first layer. The electrode layer is composed of a solvent mixed with an electrode active material. The first layer is composed of a first resin. The second layer is composed of a second resin different from the first resin. The difference between the solubility parameter of the first resin and the solubility parameter of the solvent is larger than the difference between the solubility parameter of the second resin and the solubility parameter of the solvent.

[0007] According to this configuration, the solvent constituting the electrode layer dissolves more easily in the second resin than in the first resin. That is, due to the difference in solubility parameters, the solvent dissolves more easily in the second resin of the second layer arranged on the electrode layer side, but dissolves less easily in the first resin of the first layer arranged on the metal foil side. Therefore, the electrode active material in the electrode layer easily penetrates into the second layer together with the solvent, but does not easily penetrate into the first layer. By the electrode active material penetrating into the second layer, in a battery from which the solvent has been removed, the electrode active material is less likely to peel off from the second layer (i.e., the resin layer). On the other hand, since the electrode active material hardly penetrates into the first layer, the electrode active material is less likely to come into contact with the metal foil. Therefore, it is possible to simultaneously make it difficult for the electrode active material to come into contact with the metal foil and to make it difficult for the electrode active material to peel off from the resin layer.

[0008] In a second aspect of the present technology, an electrode structure includes a metal foil, a resin layer disposed on the metal foil, and an electrode layer disposed on the resin layer. The resin layer includes a first layer disposed on the metal foil and a second layer disposed on the first layer. The electrode layer is made of a solvent mixed with an electrode active material. The first layer is made of a first resin. The second layer is made of a second resin different from the first resin. The density of the first resin is higher than the density of the second resin.

[0009] The solvent constituting the electrode layer dissolves more easily in the resin as the density of the resin decreases. Therefore, the solvent dissolves more easily in the second resin than in the first resin. This makes it easier for the electrode active material in the electrode layer to penetrate into the second layer but less easily into the first layer. Therefore, even with this configuration, it is possible to simultaneously make it difficult for the electrode active material to come into contact with the metal foil and for the electrode active material to peel off from the resin layer.

[0010] In a third aspect of the present technology, an electrode structure includes a metal foil, a resin layer disposed on the metal foil, and an electrode layer disposed on the resin layer. The resin layer includes a first layer disposed on the metal foil and a second layer disposed on the first layer. The electrode layer is composed of a solvent mixed with an electrode active material. The first layer is composed of a first resin. The second layer is composed of a second resin different from the first resin. The molecular weight of the first resin is greater than the molecular weight of the second resin.

[0011] The solvent constituting the electrode layer dissolves more easily in the resin as the molecular weight of the resin decreases. Therefore, the solvent dissolves more easily in the second resin than in the first resin. This makes it easier for the electrode active material in the electrode layer to penetrate into the second layer but less easily into the first layer. Therefore, even with this configuration, it is possible to simultaneously make it difficult for the electrode active material to come into contact with the metal foil and for the electrode active material to peel off from the resin layer. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1 is a diagram showing a schematic configuration of an electrode structure according to an embodiment. [Figure 2] 1A and 1B are diagrams showing a method for manufacturing an electrode structure according to an embodiment, in which (a) shows a state in which a first layer is disposed on a metal foil, (b) shows a state in which a second layer is disposed on the first layer, and (c) shows a state in which an electrode layer is disposed on the second layer (i.e., an electrode structure). [Figure 3] 1A and 1B are diagrams showing a method for manufacturing a battery from an electrode structure according to an embodiment, in which (a) shows a state in which the second resin constituting the second layer and the solvent constituting the electrode layer are dissolved, and (b) shows a state in which the solvent has been removed from the electrode structure (i.e., a battery). DETAILED DESCRIPTION OF THE INVENTION

[0013] Example 1 An electrode structure 10 of this embodiment will be described with reference to the drawings. The electrode structure 10 is a semi-finished product used in manufacturing a battery 1. The battery 1 is manufactured by removing a solvent 34 (described below) that constitutes an electrode layer 30 from the electrode structure 10. As shown in FIG. 1, the electrode structure 10 includes a metal foil 12, a resin layer 14, and an electrode layer 30.

[0014] The metal foil 12 is made of a metal having high conductivity. In this embodiment, the metal foil 12 is a copper foil. The type of metal constituting the metal foil 12 is not particularly limited, and the metal foil 12 may be made of other metals such as aluminum, nickel, stainless steel, etc.

[0015] The resin layer 14 is disposed on the metal foil 12. The resin layer 14 is composed of resins 22, 24 containing a conductive additive 20. The resin layer 14 includes multiple layers, and in this embodiment includes a first layer 16 disposed on the metal foil 12 and a second layer 18 disposed on the first layer 16.

[0016] The resin layer 14 includes multiple types of resins 22 and 24, and in this embodiment includes two types of resins 22 and 24 (hereinafter also referred to as a first resin 22 and a second resin 24). The first layer 16 is made of the first resin 22, and the second layer 18 is made of the second resin 24. The first resin 22 and the second resin 24 have different compositions.

[0017] The second resin 24 is a resin that is more easily soluble in a solvent 34 (described later) constituting the electrode layer 30 than the first resin 22. Specifically, the types of the first resin 22 and the second resin 24 are selected so that the difference between the solubility parameter of the first resin 22 and the solubility parameter of the solvent 34 is greater than the difference between the solubility parameter of the second resin 24 and the solubility parameter of the solvent 34. For example, the SP value or the HSP value can be used as the solubility parameter. In this embodiment, the first resin 22 is Teflon (PTFE) (registered trademark), the second resin 24 is polymethyl methacrylate, and the solvent 34 (described later) is acetone. Note that the types of the first resin 22 and the second resin 24 are not particularly limited as long as the second resin 24 is more easily soluble in the solvent 34 than the first resin 22. For example, the first resin 22 and the second resin 24 may be composed of a conductive resin or a non-conductive resin. The conductive resin is, for example, polythiophene. The non-conductive resin can be selected from thermoplastic resins and thermosetting resins. When the battery 1 manufactured from the electrode structure 10 is used as a positive electrode, the first resin 22 and the second resin 24 may be a resin such as a polyvinylidene fluoride (PVdF) resin or a polyacrylic acid resin. When the battery 1 manufactured from the electrode structure 10 is used as a negative electrode, the first resin 22 and the second resin 24 may be a resin such as a polyacrylic acid resin, polyamideimide, or styrene-butadiene rubber.

[0018] The resin layer 14 contains the same type of conductive additive 20. That is, the first layer 16 and the second layer 18 contain the same type of conductive additive 20. The type of conductive additive 20 is not particularly limited. For example, the conductive additive 20 can be formed from a carbon material or a metal material. Carbon materials come in various shapes, such as particulate (solid, hollow, or porous), fibrous, tubular, brush-like, and chip-like (or flat) shapes, and any of these may be used. Metal materials come in shapes such as particulate and fibrous, and any of these may be used. Metal-coated carbon may also be used as the conductive additive 20. The resin layer 14 may contain one type of conductive additive 20, or multiple types of conductive additives may be combined in any ratio. The conductive additive 20 contained in the first resin 22 and the conductive additive 20 contained in the second resin 24 may be different types of conductive additives, and the first resin 22 and the second resin 24 may each contain one type of conductive additive, or multiple types of conductive additives may be mixed in any ratio.

[0019] The electrode layer 30 is disposed on the resin layer 14 (more specifically, the second layer 18). The electrode layer 30 is in a slurry state and is composed of a solvent 34 mixed with an electrode active material 32. The electrode layer 30 may contain various substances in addition to the electrode active material 32 and the solvent 34. For example, the electrode layer 30 may contain additives such as a conductive aid, a binder, a thickener, or a dispersant. Furthermore, when the battery 1 manufactured from the electrode structure 10 is an all-solid-state battery, the electrode layer 30 may further contain an electrolyte.

[0020] The electrode layer 30 contains a mixture of the same type of electrode active material 32. The type of electrode active material 32 is not particularly limited. For example, the electrode active material 32 may be made of graphite. When the battery 1 manufactured from the electrode structure 10 is used as a positive electrode, the electrode active material 32 may be made of a material selected from the group consisting of LCO (LiCoO), LiNi 1 / 3 Co 1 / 3 Mn 1 / 3The electrode active material 32 can be formed of, but is not limited to, NCM-based materials such as O2, LFP (LiFePO4), LiMn2O4, etc. When the battery 1 manufactured from the electrode structure 10 is used as a negative electrode, the electrode active material 32 can be formed of Si, SiO, graphite, LTO (Li4Ti5O 12 ), but is not limited to these. The electrode active material 32 may be solid particles, porous particles, or other shapes.

[0021] The solvent 34 is used to mix various substances contained in the electrode layer 30 to form a slurry of the electrode layer 30. The type of solvent 34 is not particularly limited. In this embodiment, the solvent 34 is acetone, but the solvent 34 may be other substances such as NMP (N-methylpyrrolidone) or water.

[0022] As described above, the difference between the solubility parameter of the first resin 22 and the solubility parameter of the solvent 34 is greater than the difference between the solubility parameter of the second resin 24 and the solubility parameter of the solvent 34. The closer the solubility parameter values ​​of two substances, the easier they are to dissolve. Because the difference between the solubility parameter of the first resin 22 and the solubility parameter of the solvent 34 is greater than the difference between the solubility parameter of the second resin 24 and the solubility parameter of the solvent 34, the solvent 34 is more easily soluble in the second resin 24 than in the first resin 22. In other words, the solvent 34 is more easily soluble in the second resin 24 but less soluble in the first resin 22.

[0023] For example, in this embodiment, the solvent 34 is acetone, the first resin 22 is Teflon (PTFE), and the second resin 24 is polymethylmethacrylate. For example, the SP value of acetone (solvent 34) is 9.9, the SP value of Teflon (PTFE) (first resin 22) is 6.2, and the SP value of polymethylmethacrylate (second resin 24) is 9.1 to 9.5. The solubility parameter value of acetone (solvent 34) is closer to the solubility parameter value of polymethylmethacrylate (second resin 24) than the solubility parameter value of Teflon (PTFE) (first resin 22). In other words, the difference between the solubility parameter of Teflon (PTFE) (first resin 22) and the solubility parameter of acetone (solvent 34) is greater than the difference between the solubility parameter of polymethylmethacrylate (second resin 24) and the solubility parameter of acetone (solvent 34). Therefore, acetone (solvent 34) dissolves easily in polymethyl methacrylate (second resin 24), but does not dissolve easily in Teflon (PTFE) (first resin 22).

[0024] Next, a method for manufacturing the electrode structure 10 will be described. First, a resin slurry containing a conductive additive 20 and a first resin 22 (hereinafter also referred to as a first resin slurry) is applied to the surface of the metal foil 12. The first resin slurry may contain other substances such as a dispersant or a dispersion medium. Next, the first resin slurry applied to the surface of the metal foil 12 is dried. As a result, a first layer 16 is formed on the metal foil 12, as shown in FIG. 2(a).

[0025] Next, a resin slurry containing a conductive additive 20 and a second resin 24 (hereinafter also referred to as a second resin slurry) is applied to the surface of the first layer 16. The second resin slurry may also contain other substances such as a dispersant or a dispersion medium. Next, the second resin slurry applied to the surface of the first layer 16 is dried. As a result, a second layer 18 is formed on the first layer 16, as shown in FIG. 2(b).

[0026] 2(c), the electrode layer 30 is applied to the surface of the second layer 18. In this way, the electrode structure 10 is formed.

[0027] Next, a method for manufacturing a battery 1 from the electrode structure 10 will be described. As shown in FIG. 3( a), when the electrode structure 10 is formed, the solvent 34 constituting the electrode layer 30 dissolves in the resin (specifically, the second resin 24) constituting the resin layer 14. In the electrode structure 10, the electrode layer 30 is disposed on the second layer 18. Because the second layer 18 and the electrode layer 30 are in contact with each other, the second resin 24 constituting the second layer 18 comes into contact with the solvent 34 in the electrode layer 30. As described above, the solvent 34 is easily soluble in the second resin 24. Therefore, contact between the second layer 18 and the electrode layer 30 dissolves the solvent 34 and the second resin 24. Then, the electrode active material 32 penetrates into the second layer 18 together with the solvent 34. On the other hand, the solvent 34 is less soluble in the first resin 22. For this reason, even if the solvent 34 dissolved in the second resin 24 in the second layer 18 reaches the first layer 16, the solvent 34 hardly dissolves in the first resin 22. Therefore, the electrode active material 32 penetrates into the second layer 18, but hardly penetrates into the first layer 16.

[0028] Next, the solvent 34 is dried. As a result, the battery 1 is formed as shown in FIG. 3(b). The solvent 34 is dried in a state in which the electrode active material 32 has penetrated into the second layer 18 but has hardly penetrated into the first layer 16. Therefore, in the battery 1, the electrode active material 32 has penetrated into the second layer 18 but has hardly penetrated into the first layer 16. The penetration of the electrode active material 32 into the second layer 18 creates an anchor effect between the electrode active material 32 and the resin layer 14 (second layer 18), making the electrode active material 32 less likely to peel off from the battery 1.

[0029] For example, if the resin layer 14 is composed only of the second resin 24 (composed only of the second layer 18 without the first layer 16), there is a risk that the electrode active material 32 will penetrate the entire resin layer 14 and reach the metal foil 12. If the electrode active material 32 reaches the metal foil 12, the metal foil 12 may be damaged. Furthermore, if the resin layer 14 is composed only of a resin that is difficult to dissolve in the solvent 34 (for example, the first resin 22) in order to prevent the electrode active material 32 from reaching the metal foil 12, the electrode active material 32 will be less likely to penetrate into the resin layer 14, and the anchor effect generated between the electrode active material 32 and the resin layer 14 will be reduced. In this example, the difference between the solubility parameter of the first resin 22 and the solubility parameter of the solvent 34 is larger than the difference between the solubility parameter of the second resin 24 and the solubility parameter of the solvent 34. This makes it easier for the electrode active material 32 to penetrate into the second layer 18 on the electrode active material 32 side, but makes it difficult for the electrode active material 32 to penetrate into the first layer 16 on the metal foil 12 side. Therefore, the electrode active material 32 easily penetrates into the second layer 18, but hardly penetrates into the first layer 16. By manufacturing a battery 1 using the electrode structure 10 of this example, in the battery 1, the electrode active material 32 is less likely to come into contact with the metal foil 12, and the electrode active material 32 is less likely to peel off from the battery 1.

[0030] Example 2 In the first embodiment described above, the types of the first resin 22 and the second resin 24 were selected so that the difference between the solubility parameter of the first resin 22 and the solubility parameter of the solvent 34 was greater than the difference between the solubility parameter of the second resin 24 and the solubility parameter of the solvent 34. However, this is not a limitation. It is sufficient that the second resin 24 dissolves more easily in the solvent 34 than the first resin 22. For example, the density of the first resin 22 may be higher than the density of the second resin 24. Specifically, the types of the first resin 22 and the second resin 24 can be selected so that the density of the first resin 22 is higher than the density of the second resin 24. As long as the density of the first resin 22 is higher than the density of the second resin 24, the types of the first resin 22 and the second resin 24 are not particularly limited. The lower the density of the resin, the more easily the solvent 34 dissolves in the resin. For example, in this embodiment, high-density polyethylene (HDPE, density 0.942 to 0.970 g / cm) is used as the first resin 22. 3) is used, and low-density polyethylene (LDPE, density 0.910 to 0.930 g / cm 3 ) is used as the second resin 24. 3 A resin 32 having a density less than 1000 kJ / cm2 can be used. The density of the high-density polyethylene (first resin 22) is higher than the density of the low-density polyethylene (second resin 24). Therefore, the solvent 34 dissolves easily in the low-density polyethylene (second resin 24) but does not dissolve easily in the high-density polyethylene (first resin 22). Because the density of the first resin 22 is higher than the density of the second resin 24, when a battery 1 is manufactured using the electrode structure 10, the electrode active material 32 easily penetrates into the second layer 18 but does not easily penetrate into the first layer 16. Therefore, in this embodiment as well, when a battery 1 is manufactured using the electrode structure 10, the electrode active material 32 is less likely to come into contact with the metal foil 12 in the battery 1 and is less likely to peel off from the battery 1.

[0031] Example 3 Furthermore, the molecular weight of the first resin 22 may be greater than the molecular weight of the second resin 24. Specifically, the types of the first resin 22 and the second resin 24 may be selected so that the molecular weight of the first resin 22 is greater than the molecular weight of the second resin 24. As long as the molecular weight of the first resin 22 is greater than the molecular weight of the second resin 24, the types of the first resin 22 and the second resin 24 are not particularly limited. The smaller the molecular weight of the resin, the more easily the solvent 34 dissolves in the resin. For example, in this embodiment, polyacrylic acids with different molecular weights can be used as the first resin 22 and the second resin 24. As an example, polyacrylic acid with an average molecular weight of 1,000,000 g / mol (hereinafter also referred to as high-molecular-weight polyacrylic acid) can be used as the first resin 22, and polyacrylic acid with an average molecular weight of 5,000 g / mol (hereinafter also referred to as low-molecular-weight polyacrylic acid) can be used as the second resin 24. The molecular weight of the high-molecular-weight polyacrylic acid (first resin 22) is greater than the molecular weight of the low-molecular-weight polyacrylic acid (second resin 24). Therefore, the solvent 34 dissolves easily in the low-molecular-weight polyacrylic acid (second resin 24) but does not dissolve easily in the high-molecular-weight polyacrylic acid (first resin 22). Because the molecular weight of the first resin 22 is greater than the molecular weight of the second resin 24, when a battery 1 is manufactured using the electrode structure 10, the electrode active material 32 easily penetrates into the second layer 18 but does not easily penetrate into the first layer 16. Therefore, in this example as well, when a battery 1 is manufactured using the electrode structure 10, the electrode active material 32 is less likely to come into contact with the metal foil 12 in the battery 1 and is less likely to peel off from the battery 1.

[0032] The above-described Examples 1 to 3 may be combined. For example, the above-described Examples 1 and 3 may be combined, and the types of the first resin 22 and the second resin 24 may be selected so that the difference between the solubility parameter of the first resin 22 and the solubility parameter of the solvent 34 is greater than the difference between the solubility parameter of the second resin 24 and the solubility parameter of the solvent 34, and the molecular weight of the first resin 22 is greater than the molecular weight of the second resin 24. The above-described Examples 1 and 2 may be combined, and the types of the first resin 22 and the second resin 24 may be selected so that the difference between the solubility parameter of the first resin 22 and the solubility parameter of the solvent 34 is greater than the difference between the solubility parameter of the second resin 24 and the solubility parameter of the solvent 34, and the density of the first resin 22 is greater than the density of the second resin 24. The above-described Examples 2 and 3 may be combined, and the types of the first resin 22 and the second resin 24 may be selected so that the molecular weight of the first resin 22 is greater than the molecular weight of the second resin 24, and the density of the first resin 22 is greater than the density of the second resin 24. Furthermore, by combining Examples 1 to 3, the types of first resin 22 and second resin 24 may be selected so that the difference between the solubility parameter of first resin 22 and the solubility parameter of solvent 34 is greater than the difference between the solubility parameter of second resin 24 and the solubility parameter of solvent 34, the density of first resin 22 is higher than the density of second resin 24, and the molecular weight of first resin 22 is greater than the molecular weight of second resin 24.

[0033] Furthermore, in the above Examples 1 to 3, the resin layer 14 and the electrode layer 30 were disposed on only one side of the metal foil 12, but the present invention is not limited to such a configuration. For example, the resin layer 14 and the electrode layer 30 may be disposed on both sides of the metal foil 12. In this case, the first layer 16 of the resin layer 14 on the metal foil 12 side and the second layer 18 on the electrode layer 30 side may have the same configuration on both sides of the metal foil 12. Furthermore, as long as the second layer 18 on the electrode layer 30 side has a configuration that is more easily dissolved in the solvent 34 than the first layer 16 on the metal foil 12 side (the configurations of the above Examples 1 to 3), the configurations of the first layer 16 and the second layer 18 disposed on one side of the metal foil 12 may be different from the configurations of the first layer 16 and the second layer 18 disposed on the other side of the metal foil 12.

[0034] Although specific examples of the present invention have been described in detail above, these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and variations of the specific examples exemplified above. The technical elements described in this specification or drawings exhibit technical utility alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. Furthermore, the technology exemplified in this specification or drawings can achieve multiple objectives simultaneously, and achieving one of these objectives itself has technical utility. [Explanation of symbols]

[0035] 1:Battery 10: Electrode structure 12: Metal foil 14: Resin layer 16: 1st layer 18:Second layer 20: Conductive additive 22: First resin 24: Second resin 30: Electrode layer 32: Electrode active material 34: Solvent

Claims

1. Metal foil; a resin layer disposed on the metal foil; an electrode layer disposed on the resin layer, the resin layer includes a first layer disposed on the metal foil and a second layer disposed on the first layer; The electrode layer is made of a solvent mixed with an electrode active material, the first layer is made of a first resin, the second layer is made of a second resin different from the first resin, An electrode structure, wherein the difference between the solubility parameter of the first resin and the solubility parameter of the solvent is greater than the difference between the solubility parameter of the second resin and the solubility parameter of the solvent.

2. Metal foil; a resin layer disposed on the metal foil; an electrode layer disposed on the resin layer, the resin layer includes a first layer disposed on the metal foil and a second layer disposed on the first layer; The electrode layer is made of a solvent mixed with an electrode active material, the first layer is made of a first resin, the second layer is made of a second resin different from the first resin, The electrode structure, wherein the density of the first resin is higher than the density of the second resin.

3. Metal foil; a resin layer disposed on the metal foil; an electrode layer disposed on the resin layer, the resin layer includes a first layer disposed on the metal foil and a second layer disposed on the first layer; The electrode layer is made of a solvent mixed with an electrode active material, the first layer is made of a first resin, the second layer is made of a second resin different from the first resin, The electrode structure, wherein the molecular weight of the first resin is greater than the molecular weight of the second resin.

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