Method for manufacturing electrode plate, electrode plate, electrode body, and battery

Abstract

This method for manufacturing an electrode plate includes: a preparation step for preparing a strip-shaped original material 60 having a first main surface 61 and a second main surface, the original material 60 being provided with, alternately in the width direction, double-sided coated portions 63 in which an active material layer 65 is formed on the first main surface 61 and the second main surface and double-sided exposed portions 64 in which the active material layer 65 is not formed on the first main surface 61 and the second main surface; a forming step for forming at least one identification display portion 70 in the double-sided exposed portions 64; and, after the forming step, a cutting step for cutting the original material 60 along the longitudinal direction thereof to obtain an electrode plate including the double-sided coated portion 63 and the double-sided exposed portion 64 in which the identification display portion 70 is formed. This allows the identification display portion to be formed with high precision.

Description

Electrode plate manufacturing method, electrode plate, electrode body, and battery

[0001] The present disclosure relates to a method for manufacturing an electrode plate, an electrode plate, an electrode assembly, and a battery.

[0002] Conventionally, there has been known an electrode plate provided with an identification marking for checking the history of the manufacturing process (for example, see Patent Document 1). The electrode plate in Patent Document 1 includes a current collector at least partially coated with an active material, and a tab connected to a plain portion of the current collector that is not coated with the active material, and the identification marking is provided on at least one of the tab and the plain portion.

[0003] Japanese Patent Application Laid-Open No. 2006-40875

[0004] However, it is believed that it is difficult to form an identification marking with high precision on the electrode plate of Patent Document 1. That is, it is difficult to form an identification marking with high precision on a narrow tab, and it is also difficult to form an identification marking with high precision on a plain area that has low strength. In this situation, one of the objects of the present disclosure is to form an identification marking with high precision.

[0005] One aspect of the present disclosure relates to a method for manufacturing an electrode plate, the method comprising: a preparation step of preparing a strip-shaped raw material having first and second main surfaces, the raw material having double-sided coated portions in which active material layers are formed on the first and second main surfaces and double-sided exposed portions in which the active material layers are not formed on the first and second main surfaces, alternating in the width direction of the raw material; a formation step of forming at least one identification marking on the double-sided exposed portion; and a cutting step of cutting the raw material along its length after the formation step to obtain an electrode plate having the double-sided coated portions and the double-sided exposed portions in which the identification markings are formed.

[0006] Another aspect of the present disclosure relates to an electrode plate, comprising: a strip-shaped core having first and second main surfaces; and active material layers formed on the first and second main surfaces, wherein the core has a double-sided coated portion where the active material layers are formed on the first and second main surfaces; and a double-sided exposed portion located adjacent to the double-sided coated portion in the width direction of the core and where the active material layers are not formed on the first and second main surfaces, wherein at least one identification mark is formed in a region of the double-sided exposed portion that is a distance of L2 / 2 or less from the double-sided coated portion, where L2 is the dimension of the double-sided exposed portion in the width direction.

[0007] Another aspect of the present disclosure relates to an electrode assembly including a first electrode plate and a second electrode plate wound with a separator interposed therebetween, the first electrode plate being the electrode plate described above.

[0008] Another aspect of the present disclosure relates to a battery including the above-described electrode assembly and a bottomed cylindrical outer can that houses the electrode assembly.

[0009] According to the present disclosure, it is possible to form an identification marking portion with high accuracy.

[0010] The novel features of the present invention are set forth in the appended claims, but the present invention, both in terms of structure and content, together with other objects and features of the present application, will be better understood from the following detailed description taken in conjunction with the drawings.

[0011] 1 is a diagram showing a raw sheet prepared in a preparation step of an example of a manufacturing method for an electrode plate according to the present disclosure, where (a) is a front view and (b) is a cross-sectional view along line IB-IB. 2 is a diagram for explaining a forming step of a manufacturing method for an electrode plate, showing a front view of a raw sheet on which an identification display part has been formed. 3 is a diagram showing an electrode plate obtained by the manufacturing method for an electrode plate, where (a) is a front view and (b) is a cross-sectional view along line IIIB-IIIB. 4 is a cross-sectional view schematically showing an example of a battery according to the present disclosure.

[0012] The following describes examples of embodiments of the electrode plate manufacturing method, electrode plate, electrode body, and battery according to the present disclosure. However, the present disclosure is not limited to the examples described below. In the following description, specific numerical values ​​and materials may be used as examples, but other numerical values ​​and materials may be used as long as the effects of the present disclosure are obtained.

[0013] (Method for manufacturing an electrode plate) The method for manufacturing an electrode plate according to the present disclosure may be a method for manufacturing an electrode plate for use in a battery, and includes a preparation step, a forming step, and a cutting step. Hereinafter, an electrode plate for use in a non-aqueous electrolyte secondary battery (e.g., a lithium ion secondary battery) will be described as an example, but the use of the electrode plate is not limited thereto. Note that in the present disclosure, the category of secondary battery also includes an electricity storage device (e.g., a lithium ion capacitor) in which at least one of the positive electrode and the negative electrode is an electrode that exhibits capacity through a non-Faradic reaction.

[0014] In the preparation step, a strip-shaped raw web having a first main surface and a second main surface is prepared. The raw web is provided with double-sided coated sections, in which active material layers are formed on the first and second main surfaces, and double-sided exposed sections, in which active material layers are not formed on the first and second main surfaces, alternately arranged in the width direction. A plurality of double-sided coated sections and a plurality of double-sided exposed sections may be provided. A double-sided coated section may be provided on both ends of the raw web in the width direction.

[0015] The base sheet may have a wide metal foil made of, for example, aluminum, an aluminum alloy, stainless steel, titanium, a titanium alloy, copper, a copper alloy, nickel, a nickel alloy, or the like, and an active material layer formed on its surface (first main surface and second main surface) and which may contain, in addition to the active material, a conductive agent, a binder, a thickener, or the like.

[0016] Examples of active materials include composite metal oxides of lithium with transition metals such as cobalt, manganese, and nickel, and carbon materials such as natural graphite, spherical or fibrous artificial graphite, non-graphitizable carbon (hard carbon), and easily graphitizable carbon (soft carbon).The active materials may be used alone or in combination of two or more.

[0017] The conductive agent may be carbon black such as acetylene black, ketjen black, channel black, furnace black, lamp black, or thermal black, or conductive fibers such as carbon fiber or metal fiber. The conductive agent for the positive electrode may be various graphites such as natural graphite and artificial graphite.

[0018] The binder is not particularly limited as long as it can be dissolved or dispersed in the dispersion medium by kneading. Examples of binders include fluororesins, rubbers, acrylic polymers, or vinyl polymers (e.g., homopolymers or copolymers of monomers such as acrylic monomers such as methyl acrylate and acrylonitrile, and vinyl monomers such as vinyl acetate). Examples of fluororesins include polyvinylidene fluoride, copolymers of vinylidene fluoride and propylene hexafluoride, and polytetrafluoroethylene. Examples of rubbers include acrylic rubber, modified acrylonitrile rubber, and styrene butadiene rubber (SBR). The binder may be used alone or in combination of two or more. Generally, fluororesins are preferred as binders for the positive electrode, and fluororesins and rubbers are preferred as binders for the negative electrode.

[0019] In the forming process, at least one identification marking is formed on the double-sided exposed portion. Two or more identification markings may be formed on each double-sided exposed portion. When the double-sided exposed portion is divided into two halves in the width direction, one or more identification markings may be formed on one half and one or more identification markings may be formed on the other half. The identification marking may be an identification marking that can identify the history of the manufacturing process. The identification marking may be, but is not limited to, a QR code (registered trademark), which is a two-dimensional code. For example, the identification marking may be composed of numbers, letters, or a combination of numbers and letters, or may be composed of protrusions, holes, or a combination of protrusions and holes. The identification marking may also be a one-dimensional code such as a barcode. The identification marking may be formed, for example, by irradiating the first main surface and / or the second main surface of the double-sided exposed portion with a laser.

[0020] In the forming step, at least one identification mark may be formed on the exposed portions on both sides while tension is being applied to the raw web. In this case, the exposed portions on both sides are in a tightly tensed state compared to when tension is not being applied to the raw web, making it easier to form the identification mark with high precision.

[0021] In the cutting step, after the forming step, the raw web is cut along its longitudinal direction to obtain an electrode plate having a double-sided coated portion and a double-sided exposed portion on which an identification marking portion is formed. The raw web may be cut along the longitudinal direction of the raw web at the widthwise center of each double-sided coated portion and at the widthwise center of each double-sided exposed portion. This allows for the production of multiple electrode plates each having one double-sided coated portion and one double-sided exposed portion.

[0022] As described above, in the manufacturing method of the electrode plate according to the present disclosure, an identification marking is formed on the two-side exposed portion in the forming step, which is performed before the cutting step. During the forming step, a two-side coated portion having a strength higher than that of the two-side exposed portion is provided on both sides of the two-side exposed portion in the width direction. Therefore, the strength of the two-side exposed portion is maintained relatively high, and it is easy to form the identification marking thereon with high precision.

[0023] In the forming process, the dimension of the double-sided exposed portion in the width direction may be L1, and the identification marking may be formed in a region of the double-sided exposed portion that is a distance of L1 / 4 or less from the double-sided coated portion. In this configuration, the identification marking is formed in a region of the double-sided exposed portion adjacent to the double-sided coated portion, which has a higher strength, i.e., in a region of the double-sided exposed portion that is relatively strong. Such a high-strength region is less likely to wrinkle than the other regions of the double-sided exposed portion. Therefore, the identification marking can be formed with even greater precision.

[0024] (Electrode Plate) The electrode plate according to the present disclosure can be suitably used in a so-called end-surface current collection type battery. The electrode plate according to the present disclosure includes a strip-shaped core and an active material layer.

[0025] The core has a first main surface and a second main surface. When the electrode plate is used as a positive electrode plate, the core may be a metal foil made of, for example, aluminum, an aluminum alloy, stainless steel, titanium, a titanium alloy, etc. When the electrode plate is used as a negative electrode plate, the core may be a metal foil made of, for example, copper, a copper alloy, nickel, a nickel alloy, etc.

[0026] The active material layer is formed on the first and second main surfaces of the substrate. When the electrode plate is used as a positive electrode plate, the active material layer is a positive electrode active material layer and may contain, in addition to the positive electrode active material, a conductive agent, a binder, a thickener, etc. When the electrode plate is used as a negative electrode plate, the active material layer is a negative electrode active material layer and may contain, in addition to the negative electrode active material, a conductive agent, a binder, a thickener, etc.

[0027] The core has a double-sided coated portion and a double-sided exposed portion. The double-sided coated portion has active material layers formed on its first and second main surfaces. The double-sided exposed portion is located next to the double-sided coated portion in the width direction of the core, and no active material layers are formed on its first and second main surfaces. Therefore, the double-sided exposed portion has lower strength than the double-sided coated portion.

[0028] In contrast, in the electrode plate according to the present disclosure, the dimension of the double-sided exposed portion in the width direction of the substrate is L2, and at least one identification marking is formed in a region of the double-sided exposed portion that is a distance of L2 / 2 or less from the double-sided coated portion. In other words, the identification marking is formed in the double-sided exposed portion, which has lower strength than the double-sided coated portion, but in a region of the double-sided exposed portion that is closer to the double-sided coated portion and has relatively higher strength. This allows the identification marking to be formed with high precision. Furthermore, because no uncoated region for forming the identification marking is provided in the region where the double-sided coated portion is provided, the identification marking can be formed without reducing battery capacity.

[0029] (Electrode assembly) The electrode assembly according to the present disclosure includes a first electrode plate and a second electrode plate wound with a separator interposed therebetween. That is, the electrode assembly according to the present disclosure is a wound-type electrode assembly. The first electrode plate is the electrode plate described above. The first electrode plate may be either a negative electrode plate or a positive electrode plate. The second electrode plate may also be the electrode plate described above.

[0030] The separator may be formed in a strip shape. The separator may be made of a polyolefin-based material or a porous film made of a combination of a polyolefin-based material and a heat-resistant material. Examples of porous films made of polyolefin-based materials include porous films made of polyethylene, polypropylene, and ethylene-propylene copolymers. These resins may be used alone or in combination of two or more. Other thermoplastic polymers may be used in combination with the polyolefin, if necessary. Examples of heat-resistant materials include heat-resistant resins and inorganic fillers. The porous film may be a single film or a multilayer film. The multilayer film may include a film made of a mixture of a heat-resistant resin and an inorganic filler.

[0031] In the electrode assembly according to the present disclosure, the identification marking may be exposed to the outside, in which case information relating to the identification marking can be obtained without disassembling the electrode assembly, which is a wound body.

[0032] (Battery) A battery according to the present disclosure includes the electrode assembly described above and a bottomed, cylindrical outer can that houses the electrode assembly. The outer can may be, for example, a bottomed cylindrical shape or a bottomed, rectangular tubular shape. A core may be in contact with the inner surface of the outer can. The outer can may house a non-aqueous electrolyte together with the electrode assembly. The non-aqueous electrolyte may be prepared by dissolving a lithium salt in a non-aqueous solvent. Examples of non-aqueous solvents include cyclic carbonates such as ethylene carbonate, propylene carbonate, and butylene carbonate; chain carbonates such as dimethyl carbonate and diethyl carbonate; and lactones such as γ-butyrolactone. The non-aqueous solvents may be used alone or in combination.

[0033] Examples of lithium salts include lithium salts with strong electron-withdrawing properties, such as LiPF, LiBF, LiClO, LiAsF, LiCFSO, LiN(SOCF), LiN(SOCF) and LiC(SOCF). These lithium salts can be used alone or in combination. The concentration of the lithium salt in the nonaqueous electrolyte is, for example, 0.5 to 1.5 M, preferably 0.7 to 1.2 M.

[0034] The non-aqueous electrolyte may contain additives as appropriate. For example, vinylene carbonate (VC), cyclohexylbenzene (CHB), and modified forms thereof may be used to form good films on the positive and negative electrodes. For example, terphenyl, cyclohexylbenzene, diphenyl ether, and the like may be used as additives that act when the non-aqueous electrolyte secondary battery is overcharged. The additives may be used alone or in combination of two or more. The proportion of these additives is not particularly limited, but is, for example, about 0.05 to 10 wt % of the non-aqueous electrolyte.

[0035] As described above, according to the present disclosure, by forming an identification marking on a double-sided exposed portion sandwiched between double-sided coated portions, the identification marking can be formed with high accuracy. Also, according to the present disclosure, by forming an identification marking on a region of the double-sided exposed portion near the double-sided coated portions, the identification marking can be formed with high accuracy.

[0036] Below, examples of an electrode plate manufacturing method, an electrode plate, an electrode assembly, and a battery according to the present disclosure will be described in detail with reference to the drawings. The above-described processes and components can be applied to the steps and components of the electrode plate manufacturing method, electrode plate, electrode assembly, and battery of the example described below. The steps and components of the electrode plate manufacturing method, electrode plate, electrode assembly, and battery of the example described below can be modified based on the above description. Furthermore, the matters described below may be applied to the above-described embodiment. Among the steps and components of the electrode plate manufacturing method, electrode plate, electrode assembly, and battery of the example described below, steps and components that are not essential for the electrode plate manufacturing method, electrode plate, electrode assembly, and battery according to the present disclosure may be omitted. Note that the diagrams shown below are schematic and do not accurately reflect the actual shapes and numbers of components.

[0037] The following first describes the method for manufacturing an electrode plate of this embodiment, and then describes the battery 10 of this embodiment. As will be described later, the battery 10 of this embodiment includes an electrode plate 22 manufactured by the method for manufacturing an electrode plate of this embodiment.

[0038] (Method for Manufacturing Electrode Plate) As shown in FIGS. 1 to 3, the method for manufacturing an electrode plate according to this embodiment includes a preparation step, a forming step, and a cutting step.

[0039] In the preparation step, as shown in FIG. 1 , a strip-shaped (or long sheet-shaped) raw web 60 having a first main surface 61 and a second main surface 62 is prepared. The strip-shaped raw web 60 has double-sided coated sections 63 and double-sided exposed sections 64 alternately arranged in its width direction (the vertical direction in FIG. 1 ). The double-sided coated sections 63 have active material layers 65 formed on the first main surface 61 and the second main surface 62. The double-sided exposed sections 64 have no active material layers formed on the first main surface 61 and the second main surface 62. The active material layers 65 in this embodiment are negative electrode active material layers, but are not limited thereto and may be positive electrode active material layers.

[0040] 2, at least one (two in this example) identification marking portion 70 is formed on each of the two-sided exposed portions 64. The identification marking portion 70 can be formed by irradiating the two-sided exposed portions 64 with a laser while the web 60 is being transported by transport rollers (not shown). At this time, it is preferable to apply a tension of a predetermined value or more to the web 60.

[0041] In the forming process of this embodiment, the dimension of the double-sided exposed portion 64 in the width direction of the original roll 60 is L1, and the identification display portion 70 is formed in an area of ​​the double-sided exposed portion 64 that is a distance of L1 / 4 or less from the double-sided coated portion 63, but this is not limited to this.

[0042] 2 and 3, after the forming step, the raw web 60 is cut along its longitudinal direction to obtain an electrode plate 22 having a double-sided coated portion 63 and a double-sided exposed portion 64 on which an identification display portion 70 is formed. Note that in FIG. 2, the cutting line for cutting the raw web 60 is shown by a two-dot chain line.

[0043] 3 , the electrode plate 22 includes a strip-shaped core 22a having a first main surface 61 and a second main surface 62, and an active material layer 65 formed on the first main surface 61 and the second main surface 62. The core 22a has a double-sided coated portion 63 in which the active material layer 65 is formed on the first main surface 61 and the second main surface 62, and a double-sided exposed portion 64 that is disposed adjacent to the double-sided coated portion 63 in the width direction of the core 22a (the vertical direction in FIG. 3 ) and in which the active material layer 65 is not formed on the first main surface 61 or the second main surface 62.

[0044] The dimension of the double-sided exposed portion 64 in the width direction of the core 22a is L2, and the identification marking portion 70 is formed in a region of the double-sided exposed portion 64 that is a distance of L2 / 2 or less from the double-sided coated portion 63. This is because, in the above-mentioned forming process, the identification marking portion 70 is formed in a region of the double-sided exposed portion 64 that is a distance of L1 / 4 or less from the double-sided coated portion 63. Note that, in Figure 3(b), the identification marking portion 70 is shown as protruding from the first main surface 61, but this is for the purpose of facilitating understanding, and the identification marking portion 70 does not have to protrude from the first main surface 61.

[0045] (Battery) The battery 10 of this embodiment is configured as a lithium-ion secondary battery, but is not limited to this. As shown in Fig. 4, the battery 10 includes a wound electrode assembly 20, a positive electrode current collector 31, a negative electrode current collector 32, an outer can 40, and a sealing plate 51.

[0046] The electrode assembly 20 is formed by winding a strip-shaped first electrode plate 21 and a strip-shaped second electrode plate 22 with a strip-shaped separator 23 interposed therebetween. In this embodiment, the first electrode plate 21 is a positive electrode plate, and the second electrode plate 22 is a negative electrode plate. In this embodiment, the second electrode plate 22 is an electrode plate 22 manufactured by the above-described electrode plate manufacturing method. Although the separator 23 is exposed at the outermost periphery of the electrode assembly 20, this is not limitative. For example, the core of the first electrode plate 21 or the core 22a of the second electrode plate 22 may be exposed at the outermost periphery of the electrode assembly 20.

[0047] The first electrode plate 21 has a double-sided coated portion 21 a in which positive electrode active material layers (not shown) are formed on both sides of a strip-shaped core body, and a double-sided exposed portion 21 b adjacent to the double-sided coated portion 21 a in which no positive electrode active material layers are formed. The core body is made of, for example, aluminum foil or aluminum alloy foil.

[0048] The second electrode plate 22 is arranged so that its double-sided exposed portion 64 is on the bottom side (the lower side in FIG. 4 ) of the outer can 40. The double-sided coated portion 63 of the second electrode plate 22 faces the double-sided coated portion 21 a of the first electrode plate 21 with the separator 23 interposed therebetween.

[0049] The positive electrode current collector 31 is disposed above the electrode body 20 and is connected by welding to the exposed portions 21b on both surfaces of the first electrode plate 21. The positive electrode current collector 31 is made of, for example, stainless steel.

[0050] The negative electrode current collector 32 is disposed below the electrode body 20 and is connected by welding to the double-sided exposed portions 64 of the second electrode plate 22. The negative electrode current collector 32 is made of, for example, a nickel alloy.

[0051] The exterior can 40 is made of metal and is formed into a cylindrical shape with a bottom and an opening at one end (the upper end in FIG. 4 ). The exterior can 40 houses the electrode assembly 20, the positive electrode current collector plate 31, and the negative electrode current collector plate 32. A welding member 41 is provided on the inner bottom surface of the exterior can 40, and the negative electrode current collector plate 32 is welded to this welding member 41. Thus, the exterior can 40 of this embodiment functions as an external negative electrode terminal.

[0052] The sealing plate 51 seals the opening of the outer can 40. A gasket 52 is disposed around the periphery of the sealing plate 51, and the inside of the outer can 40 is sealed by crimping the open edge of the outer can 40 to the gasket 52. The sealing plate 51 is electrically connected to the positive electrode current collector plate 31 via a metal tab 53. Thus, the sealing plate 51 of this embodiment functions as a positive electrode external terminal.

[0053] <<Appendix>> The above embodiments disclose the following techniques. (Technology 1) A method for manufacturing an electrode plate, comprising: a preparation step of preparing a band-shaped raw material having first and second main surfaces, in which double-sided coated portions, in which an active material layer is formed on the first and second main surfaces, and double-sided exposed portions, in which the active material layer is not formed on the first and second main surfaces, are alternately arranged in the width direction of the raw material; a formation step of forming at least one identification marking on the double-sided exposed portion; and a cutting step of, after the formation step, cutting the raw material along its longitudinal direction to obtain an electrode plate having the double-sided coated portions and the double-sided exposed portions on which the identification marking is formed. (Technology 2) The method for manufacturing an electrode plate according to Technology 1, in the formation step, the identification marking is formed in a region of the double-sided exposed portion that is a distance of L1 / 4 or less from the double-sided coated portion, where L1 is the dimension of the double-sided exposed portion in the width direction. (Technology 3) An electrode plate comprising: a strip-shaped core body having a first main surface and a second main surface; and active material layers formed on the first main surface and the second main surface, wherein the core body has a double-sided coated portion where the active material layers are formed on the first main surface and the second main surface, and a double-sided exposed portion arranged adjacent to the double-sided coated portion in the width direction of the core body and where the active material layers are not formed on the first main surface and the second main surface, wherein at least one identification marking portion is formed in a region of the double-sided exposed portion that is a distance of L2 / 2 or less from the double-sided coated portion, where L2 is the dimension of the double-sided exposed portion in the width direction. (Technology 4) An electrode body comprising a first electrode plate and a second electrode plate wound with a separator interposed therebetween, wherein the first electrode plate is the electrode plate described in Technology 3. (Technology 5) A battery comprising: the electrode body described in Technology 4; and a bottomed tubular outer can that houses the electrode body.

[0054] While the present invention has been described in terms of presently preferred embodiments, such disclosure is not to be interpreted as limiting. Various changes and modifications will no doubt become apparent to those skilled in the art to which the present invention pertains upon reading the above disclosure. It is therefore intended that the appended claims be interpreted to cover all changes and modifications that do not depart from the true spirit and scope of the invention.

[0055] The present disclosure can be used for a method for manufacturing an electrode plate, an electrode plate, an electrode assembly, and a battery.

[0056] DESCRIPTION OF SYMBOLS 10: Battery 20: Electrode body 21: First electrode plate 21a: Double-sided coated portion 21b: Double-sided exposed portion 22: Second electrode plate (electrode plate) 22a: Core body 23: Separator 31: Positive electrode current collector 32: Negative electrode current collector 40: Outer can 51: Sealing plate 52: Gasket 53: Metal tab 54: Welding rod member 60: Raw material 61: First main surface 62: Second main surface 63: Double-sided coated portion 64: Double-sided exposed portion 65: Active material layer 70: Identification marking portion

Claims

1. A method for manufacturing an electrode plate, comprising: a preparation step of preparing a band-shaped original web having a first main surface and a second main surface, in which double-sided coated portions, in which an active material layer is formed on the first main surface and the second main surface, and double-sided exposed portions, in which the active material layer is not formed on the first main surface and the second main surface, are alternately provided in the width direction of the original web; a formation step of forming at least one identification marking on the double-sided exposed portion; and a cutting step of, after the formation step, cutting the original web along its longitudinal direction to obtain an electrode plate having the double-sided coated portions and the double-sided exposed portions on which the identification markings are formed.

2. A method for manufacturing an electrode plate as described in claim 1, wherein in the forming process, the dimension of the double-sided exposed portion in the width direction is L1, and the identification marking portion is formed in an area of ​​the double-sided exposed portion that is a distance of L1 / 4 or less from the double-sided coated portion.

3. An electrode plate comprising: a band-shaped core body having a first main surface and a second main surface; and an active material layer formed on the first main surface and the second main surface, wherein the core body has a double-sided coated portion where the active material layer is formed on the first main surface and the second main surface, and a double-sided exposed portion arranged adjacent to the double-sided coated portion in the width direction of the core body and where the active material layer is not formed on the first main surface and the second main surface, wherein the dimension of the double-sided exposed portion in the width direction is L2, and at least one identification marking portion is formed in an area of ​​the double-sided exposed portion that is a distance of L2 / 2 or less from the double-sided coated portion.

4. An electrode assembly comprising a first electrode plate and a second electrode plate wound with a separator interposed therebetween, the first electrode plate being the electrode plate according to claim 3.

5. A battery comprising: the electrode assembly according to claim 4; and a bottomed cylindrical exterior can housing the electrode assembly.

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