Electrode plate and battery

Abstract

A cylindrical battery (10) according to an example of an embodiment is provided with an electrode body (14) including a positive electrode plate (11) and a negative electrode plate (12) as electrode plates. The electrode plate has a core body, a mixture layer formed on the core body, a lead bonded to an exposed portion exposed from the surface of the core body, and an identification mark. At least one part of the identification mark is formed in the projection range of the outline of the projection lead in the exposed part.

Description

Technical Field

[0001] The present disclosure relates to electrode plates and batteries. Background Art

[0002] In the past, electrode plates with identification marks are known (for example, see Patent Documents 1 and 2). Based on the identification mark, the production line, manufacturing date, etc. of the electrode plate can be determined. The identification mark of the electrode plate is used to analyze the cause of a malfunction caused by some reason during the manufacturing process of the battery or after the battery leaves the factory.

[0003] Patent Document 1 describes that an identification mark is provided on at least one of the positive lead, the negative lead, the exposed core portion of the positive electrode, and the exposed core portion of the negative electrode. In addition, Patent Document 2 describes that an identification mark is provided on the exposed core portion, and a mixture layer is provided on the core surface opposite to the identification mark in the thickness direction of the core.

[0004] Prior Art Literature

[0005] Patent Document 1: Japanese Patent Application Publication No. 2006-040875

[0006] Patent Document 2: International Publication No. 2019 / 193869 Summary of the invention

[0007] As a result of the research conducted by the present inventor, it was found that, as disclosed in Patent Documents 1 and 2, when an identification mark is provided on the exposed portion of the core of the electrode plate, the identification mark is deformed due to the tensile force acting on the exposed portion during the charge and discharge of the battery, because the rigidity of the exposed portion of the core is low. If the identification mark is deformed, it is sometimes difficult to read the mark. In addition, the lead wire has higher rigidity than the exposed portion of the core and is not easily deformed during charge and discharge, but the width of the lead wire is usually small, and it is not easy to provide an identification mark on the surface of the lead wire.

[0008] The electrode plate disclosed in the present invention comprises a core body and a mixture layer formed on the core body, and is provided with an exposed portion exposing the surface of the core body, and the electrode plate comprises a lead wire connected to the exposed portion, and an identification mark. At least a part of the identification mark is formed within the projection range of the outline of the lead wire projected in the exposed portion.

[0009] The battery according to the present disclosure includes an electrode body including the electrode plate described above and an exterior body that houses the electrode body.

[0010] According to the electrode plate of the present disclosure, it is possible to suppress the identification mark from being deformed during use of the electrode plate, thereby making it difficult for the identification mark to be read incorrectly. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 It is a cross-sectional view of a cylindrical battery according to an example of the embodiment.

[0012] Figure 2 This is a plan view of a positive electrode plate according to an example of the embodiment, and shows a positive electrode lead and its vicinity.

[0013] Figure 3 This is a plan view of a negative electrode plate according to an example of the embodiment, and shows a negative electrode lead and its vicinity.

[0014] Figure 4 It is a diagram showing a modified example of the electrode plate.

[0015] Figure 5 It is a diagram showing a modified example of the electrode plate.

[0016] Figure 6 It is a diagram showing a manufacturing process of an electrode plate according to an example of an embodiment. DETAILED DESCRIPTION

[0017] Hereinafter, an example of an embodiment of the electrode plate of the present disclosure and a battery using the electrode plate will be described in detail with reference to the accompanying drawings. The embodiment described below is only an example, and the present disclosure is not limited to the following embodiment. In addition, a technical solution formed by selectively combining the constituent elements of the embodiment described below is also included in the present disclosure.

[0018] Hereinafter, as a battery, a cylindrical battery 10 is exemplified in which a wound electrode body 14 is housed in an outer can 16 having a bottomed cylindrical shape, but the outer body of the battery is not limited to a cylindrical outer can. The battery disclosed herein may be, for example, a square battery having a square outer can, or a coin-shaped battery having a coin-shaped outer can, or a pouch-shaped battery having an outer body composed of a laminate sheet including a metal layer and a resin layer. In addition, the cylindrical battery 10 of the present embodiment is a secondary battery, but the electrode plate disclosed herein can also be applied to power storage devices other than secondary batteries such as primary batteries and capacitors.

[0019] Figure 1 1 is a diagram schematically showing an axial cross section of a cylindrical battery 10 according to an example of an embodiment. Figure 1 As shown, the cylindrical battery 10 includes an electrode body 14, an electrolyte, and an outer can 16 for storing the electrode body 14 and the electrolyte. The electrode body 14 includes a positive electrode plate 11, a negative electrode plate 12, and a separator 13, and has a structure in which the positive electrode plate 11 and the negative electrode plate 12 are wound in a spiral shape with the separator 13 interposed therebetween. The outer can 16 is a metal container in a bottomed cylindrical shape with one side open in the axial direction, and the opening of the outer can 16 is sealed by a sealing body 17. In the following, for convenience of description, the sealing body 17 side of the cylindrical battery 10 is set as the upper side, and the bottom side of the outer can 16 is set as the lower side.

[0020] The electrolyte may be an aqueous electrolyte, but a non-aqueous electrolyte is used in the present embodiment. The non-aqueous electrolyte comprises a non-aqueous solvent and an electrolyte salt dissolved in the non-aqueous solvent. The non-aqueous solvent may be, for example, esters, ethers, nitriles, amides, and mixed solvents of two or more thereof. As an example of a non-aqueous solvent, ethylene carbonate (EC), ethyl methyl carbonate (EMC), dimethyl carbonate (DMC), diethyl carbonate (DEC), and mixed solvents thereof may be cited. The non-aqueous solvent may contain a halogen substitute (e.g., fluoroethylene carbonate, etc.) in which at least a portion of the hydrogen of these solvents is replaced by a halogen atom such as fluorine. The electrolyte salt may be, for example, a lithium salt such as LiPF6.

[0021] The positive electrode plate 11, the negative electrode plate 12 and the separator 13 constituting the electrode body 14 are all strip-shaped long bodies, which are alternately stacked in the radial direction of the electrode body 14 by being wound into a spiral shape. In order to prevent the precipitation of lithium, the negative electrode plate 12 is formed to be one circle larger than the positive electrode plate 11. In other words, the negative electrode plate 12 is formed longer than the positive electrode plate 11 in the length direction and the width direction (short side direction). The separator 13 is formed to be at least one circle larger than the positive electrode plate 11, and two sheets are arranged in a manner of sandwiching the positive electrode plate 11.

[0022] The positive electrode plate 11 has a positive electrode core 30 and a positive electrode mixture layer 31 formed on the positive electrode core 30. The positive electrode core 30 can be made of a foil of a metal such as aluminum or aluminum alloy that is stable within the potential range of the positive electrode plate 11, or a thin film having the metal disposed on the surface. The positive electrode mixture layer 31 preferably contains a positive electrode active material, a conductive agent such as carbon black or carbon nanotubes, and a binder such as polyvinylidene fluoride, and is formed on the exposed portion 32 (see Figure 2 ) on both sides of the positive electrode core 30. The positive electrode plate 11 can be manufactured by applying a positive electrode mixture slurry containing a positive electrode active material, a conductive agent, and a binder on both sides of the positive electrode core 30 and compressing the coating film.

[0023] An example of the positive electrode active material contained in the positive electrode mixture layer 31 is a lithium transition metal composite oxide. The lithium transition metal composite oxide is a composite oxide containing metal elements such as Co, Mn, Ni, and Al in addition to Li. The metal element constituting the composite oxide is, for example, at least one selected from Mg, Al, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Ge, Y, Zr, Sn, Sb, W, Pb, and Bi. Among them, it is preferred to contain at least one selected from Ni, Mn, and Co.

[0024] The negative electrode plate 12 includes a negative electrode core 40 and a negative electrode mixture layer 41 formed on the negative electrode core 40. The negative electrode core 40 may be made of a foil of a metal such as copper or a copper alloy that is stable within the potential range of the negative electrode plate 12, or a thin film having the metal disposed on the surface. The negative electrode mixture layer 41 preferably contains a negative electrode active material, a binder, and, if necessary, a conductive agent such as carbon black or carbon nanotubes, and is formed on the exposed portion 42 (see Figure 3 ) on both sides of the negative electrode core 40 other than the negative electrode core 40. The binder may be, for example, styrene-butadiene rubber (SBR), or carboxymethyl cellulose or its salt. The negative electrode plate 12 may be manufactured by coating a negative electrode mixture slurry containing a negative electrode active material and a binder on both sides of the negative electrode core 40 and compressing the coating.

[0025] An example of the negative electrode active material contained in the negative electrode mixture layer 41 is a carbon material such as graphite that reversibly absorbs and releases lithium ions. Graphite can be any of natural graphite and artificial graphite. As the negative electrode active material, elements such as Si and Sn that alloy with Li, materials containing the elements, etc. can be used. Among them, a composite material containing Si is preferred. As a preferred example of a composite material containing Si, a material in which a fine Si phase is dispersed in a SiO2 phase, a silicate phase such as lithium silicate, a carbon phase or a silicide phase can be cited.

[0026] The separator 13 uses a porous sheet having ion permeability and insulation. Specific examples of porous sheets include microporous films, woven fabrics, non-woven fabrics, etc. As the material of the separator 13, polyolefins such as polyethylene and polypropylene, cellulose, etc. are preferred. The separator 13 can be a single-layer structure or a multi-layer structure. In addition, a resin layer with high heat resistance such as aramid resin can be formed on the surface of the separator 13. A filler layer containing an inorganic filler can be formed on the interface between the separator 13 and at least one of the positive electrode plate 11 and the negative electrode plate 12.

[0027] Insulating plates 18 and 19 are disposed above and below the electrode body 14, respectively. Figure 1 In the example shown, the positive electrode lead 20 extends to the sealing body 17 side through the through hole of the insulating plate 18, and the negative electrode lead 21 extends to the bottom side of the outer can 16 through the outside of the insulating plate 19. The positive electrode lead 20 is connected to the lower surface of the internal terminal plate 23 of the sealing body 17 by laser welding or the like, and the top plate of the sealing body 17, that is, the cover 27 electrically connected to the internal terminal plate 23 serves as the positive terminal. The negative electrode lead 21 is connected to the inner surface of the bottom of the outer can 16 by laser welding or the like, and the outer can 16 serves as the negative terminal.

[0028] The positive electrode lead 20 is connected to the positive electrode core 30 by ultrasonic welding or the like. The positive electrode lead 20 is, for example, joined to the longitudinal center of the positive electrode plate 11 away from both ends in the longitudinal direction. The positive electrode lead 20 may also be joined to a position substantially equidistant from both ends in the longitudinal direction of the positive electrode plate 11. The negative electrode lead 21 is connected to the negative electrode core 40 by ultrasonic welding or the like. Figure 1 In the example shown, a negative electrode lead 21 is joined to a longitudinal end of the negative electrode plate 12 located on the outer peripheral side of the electrode body 14. The positive electrode lead 20 and the negative electrode lead 21 are, for example, strip-shaped metal members having a thickness of 30 μm to 100 μm.

[0029] The negative electrode plate 12 may be disposed on the outer peripheral surface of the electrode body 14. In addition, an exposed portion that exposes the surface of the negative electrode core 40 may be formed on the outer peripheral surface of the electrode body 14, and the exposed portion may contact the inner surface of the outer can 16 to electrically connect the negative electrode plate 12 to the outer can 16. In this case, the negative electrode plate 12 may not have the negative electrode lead 21, and may not have the identification mark 46 described later.

[0030] As described above, the outer can 16 is a metal container in a cylindrical shape with a bottom and an opening on one side in the axial direction. A gasket 28 is provided between the outer can 16 and the sealing body 17 to ensure the airtightness of the battery interior and the insulation of the outer can 16 and the sealing body 17. The outer can 16 is provided with a groove 22 in which a part of the side surface protrudes inwardly and supports the sealing body 17. The groove 22 is preferably formed in an annular shape along the circumferential direction of the outer can 16, and supports the sealing body 17 on its upper surface. The sealing body 17 is fixed to the upper part of the outer can 16 through the groove 22 and the open end of the outer can 16 riveted relative to the sealing body 17.

[0031] The sealing body 17 has a structure in which an internal terminal plate 23, a lower valve body 24, an insulating component 25, an upper valve body 26 and a cover 27 are stacked in order from the electrode body 14 side. The components constituting the sealing body 17 have, for example, a disc shape or a ring shape, and the components except the insulating component 25 are electrically connected to each other. The lower valve body 24 and the upper valve body 26 are connected at their respective central portions, and an insulating component 25 is sandwiched between their respective peripheral portions. When an abnormality occurs in the battery and the internal pressure rises, the lower valve body 24 is deformed and ruptured in a manner that pushes the upper valve body 26 toward the cover 27 side, thereby cutting off the current path between the lower valve body 24 and the upper valve body 26. When the internal pressure rises further, the upper valve body 26 ruptures, and the gas is discharged from the opening of the cover 27.

[0032] Below, refer to Figure 2 and Figure 3 The positive electrode plate 11 and the negative electrode plate 12 are described in detail. Figure 2 and Figure 3In the figure, the mixture layer is shaded with oblique lines, and the bands 33 and 43 are shaded with dots. As described above, the positive electrode plate 11 includes a positive electrode core 30 and a positive electrode mixture layer 31 formed on both sides of the positive electrode core 30. Similarly, the negative electrode plate 12 includes a negative electrode core 40 and a negative electrode mixture layer 41 formed on both sides of the negative electrode core 40.

[0033] like Figure 2 As shown, an exposed portion 32 exposing the surface of the positive electrode core 30 is formed on the positive electrode plate 11. The exposed portion 32 is formed by not applying the positive electrode mixture slurry on the positive electrode core 30 and not providing the positive electrode mixture layer 31. Alternatively, the exposed portion 32 can also be formed by peeling off a part of the positive electrode mixture layer 31. In the present embodiment, the exposed portion 32 is formed at a point in the central part of the longitudinal direction of the positive electrode plate 11. In addition, the formation position of the exposed portion 32 is not limited to the central part of the longitudinal direction of the positive electrode plate 11, for example, it can also be formed at a plurality of locations separated along the longitudinal direction.

[0034] The positive electrode plate 11 has a positive lead 20 joined to the exposed portion 32 and an identification mark 36, and at least a portion of the identification mark 36 is formed within a projection range X of the outline of the positive lead 20 projected on the exposed portion 32, and the details will be described later. In the case where a plurality of exposed portions 32 are formed and a positive lead 20 is joined to each exposed portion 32, the identification mark 36 can be formed on any one of the exposed portions 32, but may also be formed on a plurality of exposed portions 32 or all of the exposed portions 32.

[0035] The exposed portion 32 preferably includes a first surface to which the positive electrode lead 20 is joined and a second surface opposite to the first surface. That is, the positive electrode lead 20 is joined only to one surface of the positive electrode core body 30, and the exposed portion 32 is also formed on the other surface on which the positive electrode lead 20 is not arranged. The second surface of the exposed portion 32 is formed at least within the projection range X of the positive electrode lead 20, and is preferably formed to overlap in the thickness direction of the positive electrode plate 11 with substantially the same size as the first surface.

[0036] The exposed portion 32 may be formed to have a length not extending from one end to the other end in the width direction of the positive electrode plate 11, but Figure 2 In the example shown, the exposed portion 32 is formed over the entire length in the width direction. The exposed portion 32 is formed to be wider than the positive electrode lead 20. The width of the exposed portion 32 is constant over the entire length, for example, and is 1.5 to 2.0 times the width of the positive electrode lead 20. In this case, there is no obstacle to the joining of the positive electrode lead 20, and a high capacity can be maintained. An example of the width of the exposed portion 32 is 5 mm to 8 mm.

[0037] A joint 35 with the positive lead 20 is formed on the exposed portion 32. On the first surface of the exposed portion 32, the positive lead 20 is arranged from one end in the width direction of the positive plate 11 to a predetermined position. The predetermined position is located, for example, between the center in the width direction and the other end (lower end) in the width direction of the positive plate 11. The joint 35 is a portion where the positive lead 20 is joined to the exposed portion 32, and is formed on a portion of the projection range X, which is an area where the positive lead 20 is arranged on the first surface of the exposed portion 32. The joint 35 is formed, for example, by ultrasonic welding. In this case, a fine depression is formed on the joint 35 as an ultrasonic welding mark. In the projection range X of the present embodiment, the joint 35 and the identification mark 36 are formed.

[0038] The positive electrode plate 11 is provided with a tape 33 covering the positive electrode lead 20. The tape 33 preferably covers the positive electrode lead 20, the exposed portion 32, and the region of the positive electrode mixture layer 31 adjacent to the exposed portion 32. In addition, the tape 33 preferably covers the entire exposed portion 32 including the region where the positive electrode lead 20 is present, is formed into a strip shape that is slightly larger than the exposed portion 32, and is provided extending from the exposed portion 32 in the length direction and the width direction of the positive electrode plate 11. The tape 33 is preferably provided on both surfaces of the positive electrode core 30. In addition, it is preferred that a tape 34 be provided at least in the range of the portion of the positive electrode lead 20 extending from the exposed portion 32, which faces the negative electrode plate 12 via the separator 13.

[0039] The tape 33 has, for example, a base material made of an insulating resin and an adhesive layer formed on one side of the base material. In addition, the tape 34 can be made of the same material as the tape 33. The tape 33 is preferably an insulating tape that is substantially non-conductive. The tape 33 can have a layer structure of more than three layers, and the base material can be composed of more than two layers of laminated films of the same or different types. The tape 33 can contain inorganic fillers such as titanium dioxide, aluminum oxide, silicon dioxide, and zirconium oxide, and preferably has a light transmittance to the extent that the identification mark 36 can be read through the tape 33. The tape 33 can be any one of colored transparent and colorless transparent.

[0040] As the resin constituting the base material of the belt 33, polyesters such as polyethylene terephthalate (PET), polypropylene (PP), polyimide (PI), polyphenylene sulfide (PPS), polyetherimide (PEI), polyamide, etc. can be exemplified. The adhesive layer is formed by, for example, applying an adhesive on one side of the base material. The adhesive constituting the adhesive layer can be a hot melt type that exhibits adhesiveness by heating or a thermosetting type that cures by heating. From the viewpoint of productivity, etc., an adhesive having adhesiveness at room temperature is preferred. As the adhesive constituting the adhesive layer, acrylic adhesives, synthetic rubber adhesives, etc. can be exemplified.

[0041] As described above, the identification mark 36 is formed on the exposed portion 32. The identification mark 36 is a separate mark attached to the positive electrode plate 11, and provides identification information for distinguishing from other positive electrode plates 11. Different identification marks 36 are set for each positive electrode plate 11, or for each group of a predetermined number of positive electrode plates 11. The identification mark 36 can be a batch number attached to a product group made of the same material and at the same time, or a product number attached to each product.

[0042] The identification mark 36 can distinguish each positive electrode plate 11 or each manufacturing batch, and is used to obtain information related to the manufacturing of the positive electrode plate 11. For example, the manufacturer of the positive electrode plate 11 has a database containing information related to the manufacturing of the positive electrode plate 11, which is associated with the identification mark 36 of the positive electrode plate 11. Therefore, by reading the identification mark 36 with a reading device such as a reader to identify the positive electrode plate 11, it is possible to obtain information related to the manufacturing of the positive electrode plate 11. As an example of information related to the manufacturing of the positive electrode plate 11, a history of the manufacturing process including information such as a production line and a manufacturing date and time can be cited.

[0043] The identification mark 36 is, for example, composed of at least one selected from numbers, characters, and identification codes. The identification mark 36 may be a mark composed of a combination of numbers and characters. The identification code constituting the identification mark 36 may be any one of a one-dimensional code, a two-dimensional code, and a three-dimensional code, preferably a two-dimensional code. Figure 2 In the illustrated example, a square two-dimensional code (QR code (registered trademark)) is formed as the identification mark 36 .

[0044] The identification mark 36 can be read by a reader or other reading device, and can be composed of at least one selected from a protrusion, a depression, and a through hole. Alternatively, the identification mark 36 can have a color different from the surrounding. The numbers, characters, or identification codes constituting the identification mark 36 may not have protrusions, depressions, or through holes, but only have a color different from the surrounding color.

[0045] The identification mark 36 can be formed by printing such as inkjet printing or stamping, and is preferably formed by laser marking. Laser marking is a method of forming a mark by irradiating a laser to the exposed portion 32. In the case where the identification mark 36 is a laser marking mark, for example, the mark is formed by discoloring the portion irradiated with the laser. In addition, a depression or a through hole can be formed in the portion irradiated with the laser. The laser marking mark has excellent durability, so it is difficult to have poor reading even after the positive electrode plate 11 is used.

[0046] As described above, at least a portion of the identification mark 36 is formed within the projection range X of the outline of the positive lead 20 projected on the exposed portion 32. That is, at least a portion of the identification mark 36 is formed within the range overlapping with the positive lead 20 in the thickness direction of the positive electrode plate 11. Since the positive lead 20 is thicker and more rigid than the positive electrode core 30, the projection range X of the exposed portion 32 joined to the positive lead 20 is less likely to deform with battery charging and discharging than other portions of the exposed portion 32. Therefore, by providing the identification mark 36 in the projection range X overlapping with the positive lead 20, deformation of the identification mark 36 with charging and discharging can be effectively suppressed, and reading errors of the identification mark 36 are less likely to occur.

[0047] Regarding the identification mark 36, a part of it may extend from the projection range X of the exposed portion 32, but it is preferably formed entirely within the projection range X. In this case, the deformation suppression effect of the identification mark 36 becomes more significant. In addition, the identification mark 36 is preferably formed so as not to overlap with the periphery of the projection range X. As described later Figure 5 As shown, a plurality of identification marks 36 may be formed. In this case, it is preferred that all identification marks 36 are formed within the projection range X as a whole.

[0048] The identification mark 36 is also preferably formed in a range that does not overlap with the joint 35 in the thickness direction of the positive electrode plate 11. By forming the identification mark 36 avoiding the joint 35, poor reading of the identification mark 36 due to the influence of the joint 35 can be prevented. In particular, when the joint 35 is formed by ultrasonic welding, since ultrasonic welding marks that may affect the reading of the mark are left on the joint 35, it is preferred to form the identification mark 36 in a manner that does not overlap with the joint 35 within the projection range X.

[0049] The identification mark 36 is arranged close to the bonding portion 35 in the projection range X of the exposed portion 32. Figure 2 In the example shown, the projection range X has a rectangular shape in a plan view that is long in the width direction of the positive electrode plate 11, and the joint portion 35 and the identification mark 36 are arranged in the length direction of the projection range X and are close to each other. Within a predetermined length range from the lower end of the projection range X, the joint portion 35 is not formed, and the identification mark 36 is formed so as not to extend from the projection range X. The predetermined length is preferably less than 50% of the length of the projection range X, for example, 15% to 30%. The interval between the joint portion 35 and the identification mark 36 is, for example, 5% to 15% of the length of the projection range X.

[0050] In one example of the embodiment, the identification mark 36 is formed on at least the first surface of the exposed portion 32. Since the first surface of the exposed portion 32 is the surface on which the positive lead 20 is disposed, when the identification mark 36 is formed on the first surface, the identification mark 36 is covered by the positive lead 20 and is shielded by the positive lead 20. In addition, since the tape 33 is provided on the positive lead 20, the identification mark 36 is covered by the tape 33 and the positive lead 20. In this case, for example, the identification mark 36 is read by turning over at least a portion of the tape 33 and the positive lead 20. Since the identification mark 36 is covered by the positive lead 20, there is an advantage that the identification mark 36 is unlikely to deteriorate even if the positive electrode plate 11 is used for a long time.

[0051] In another example of the embodiment, the identification mark 36 is formed at least on the second surface of the exposed portion 32. There is no positive lead 20 on the second surface, but since the tape 33 is also attached to the second surface, the identification mark 36 is in a state of being covered and protected by the tape 33. In this case, if the tape 33 is transparent, the identification mark 36 can be read through the tape 33. It is also preferable that the entirety of the identification mark 36 is formed on the second surface within the projection range X of the positive lead 20. In addition, the identification mark 36 is preferably formed within a range that does not overlap with the bonding portion 35 in the thickness direction of the positive electrode plate 11.

[0052] The identification mark 36 may be formed only on the first surface or only on the second surface of the exposed portion 32, or may be formed on both surfaces of the exposed portion 32. When the identification mark 36 is formed on both surfaces of the exposed portion 32, for example, at least a portion of each identification mark 36 overlaps with each other in the thickness direction of the positive electrode plate 11.

[0053] like Figure 3 As shown, an exposed portion 42 exposing the surface of the negative electrode core 40 is formed on the negative electrode plate 12. The exposed portion 42 is formed by not applying the negative electrode mixture slurry on the negative electrode core 40 and not providing the negative electrode mixture layer 41. Alternatively, the exposed portion 42 can also be formed by peeling off a part of the negative electrode mixture layer 41. In the present embodiment, the exposed portion 42 is formed at a location of the longitudinal end of the negative electrode plate 12 located on the outer peripheral side of the electrode body 14. In addition, the formation position of the exposed portion 42 is not limited to the longitudinal end of the negative electrode plate 12, for example, it can also be formed at a plurality of locations separated along the longitudinal direction.

[0054] Similar to the case of the positive electrode plate 11, the negative electrode plate 12 has a negative electrode lead 21 joined to the exposed portion 42, and an identification mark 46, at least a portion of which is formed within a projection range Y of the outline of the negative electrode lead 21 projected on the exposed portion 42. In the case where a plurality of exposed portions 42 are formed and one negative electrode lead 21 is joined to each exposed portion 42, the identification mark 46 may be formed at one of the plurality of exposed portions 42, or may be formed on a plurality of exposed portions 32 or all of the exposed portions 32.

[0055] The exposed portion 42 preferably includes a first surface joined to the negative electrode lead 21 and a second surface opposite to the first surface, similarly to the exposed portion 32 of the positive electrode plate 11. The exposed portion 42 is formed wider than the exposed portion 32 from one end in the longitudinal direction of the negative electrode plate 12. In addition, the negative electrode plate 12 is provided with the negative electrode lead 21, the exposed portion 42, and a tape 43 covering the region of the negative electrode mixture layer 41 adjacent to the exposed portion 42. In addition, the tape 43 does not have to cover the entire exposed portion 42. The tape 43 can use the same tape as the tape 33 of the positive electrode plate 11.

[0056] The identification mark 46 can be formed in the same structure as the identification mark 36 of the positive electrode plate 11, and thus the description of the identification mark 36 can be cited. The identification mark 46 is preferably formed entirely within the projection range Y of the exposed portion 42. In addition, the identification mark 46 is preferably formed on at least one of the first surface and the second surface of the exposed portion 42 in a range that does not overlap with the joint portion 45 of the negative lead 21.

[0057] Figure 4 and Figure 5 1 and 11B are diagrams showing modified examples (positive electrode plates 11A and 11B) of the positive electrode plate 11. The structure of this modified example can also be applied to the negative electrode plate 12.

[0058] Figure 4 The positive electrode plate 11A shown is similar to the positive electrode plate 11 in that the identification mark 36 is formed in the projection range X of the exposed portion 32 while avoiding the joint portion 35 of the positive lead 20. On the other hand, the positive electrode plate 11A is different from the positive electrode plate 11 in that the identification mark 36 is sandwiched from the top and bottom by the joint portion 35. That is, in the positive electrode plate 11A, the joint portion 35 is formed in two places of the exposed portion 32, and the identification mark 36 is formed in the area sandwiched by the joint portion 35. In this case, since the area where the identification mark 36 is formed is more strongly constrained by the positive lead 20 with high rigidity, the deformation suppression effect of the identification mark 36 becomes significant.

[0059] Figure 5The difference between the positive plate 11B shown and the positive plates 11 and 11A is that a plurality of identification marks 36 are formed within a projection range X. On the other hand, each identification mark 36 is common to the identification mark 36 of the positive plate 11A in that it is sandwiched from the top and bottom by the joint portion 35. In the positive plate 11B, the identification mark 36 can be formed in two on each side of the exposed portion 32, forming a total of four, or it can be formed in two on only one of the first and second surfaces. In this case, the identification mark 36 in good condition can be selected to read the mark. In addition, the plurality of identification marks 36 are not limited to the same mark, and can also be different marks from each other.

[0060] Figure 6 FIG. 2 shows an example of a process for forming the identification mark 36 on the exposed portion 32 of the positive electrode plate 11. Figure 6 As shown, the identification mark 36 can be formed by laser marking by irradiating the surface of the exposed portion 32 with laser α. Laser marking is a non-contact marking using laser, which can be marked at high speed. The laser α is scanned, for example, along the length direction and width direction of the positive electrode plate 11 on the exposed portion 32. The portion irradiated with the laser α changes color or becomes a tiny depression, forming an identification mark 36 (two-dimensional code). The identification mark 36 is formed in the area that becomes the projection range X by welding the positive lead 20 in the subsequent process.

[0061] The identification mark 36 may be formed before the positive electrode mixture layer 31 is formed, but it is preferred that the positive electrode mixture slurry is intermittently applied to the long strip of positive electrode core 30 to form the positive electrode mixture layer 31 and the exposed portion 32, and then the exposed portion 32 is irradiated with laser α to form the identification mark 36. It is preferred that the long strip of positive electrode core 30 formed with the positive electrode mixture layer 31 and the exposed portion 32 is transported to the irradiation point of the laser α to continuously form the identification mark 36. Figure 6 In the illustrated example, the positive electrode core body 30 in a state where a predetermined tension is applied between the conveying rollers 100 and 101 is irradiated with the laser beam α.

[0062] As described above, according to the cylindrical battery 10 having the above structure, the deformation of the identification marks 36 and 46 accompanying charging and discharging can be effectively suppressed. Therefore, it is difficult for the identification marks 36 and 46 to be read incorrectly. During the charging and discharging of the battery, a tensile force acts on the exposed portions 32 and 42, but the projection ranges X and Y of the leads are suppressed from deformation due to the effect of the highly rigid leads. Therefore, if the identification marks 36 and 46 are formed in the projection ranges X and Y of the exposed portions 32 and 42, respectively, deformation of the marks is difficult to occur. In addition, the identification marks 36 and 46 are covered by the tapes 33 and 43, respectively, and when formed on the first surface, they are further covered by the leads, so that the wear of the identification marks 36 and 46 and the degradation caused by exposure of the marks to the electrolyte, etc. can be effectively suppressed.

[0063] In addition, in the above-mentioned embodiment, the identification mark is provided on both the positive electrode plate and the negative electrode plate, but the identification mark may be provided only on the positive electrode plate or only on the negative electrode plate.

[0064] The present disclosure is further described through the following embodiments.

[0065] Technical structure 1: An electrode plate, comprising a core and a composite layer formed on the core, and an exposed portion exposing the surface of the core, the electrode plate having a lead connected to the exposed portion, and an identification mark, at least a portion of the identification mark being formed within the projection range of the outline of the lead projected in the exposed portion.

[0066] Technical Configuration 2: In the electrode plate according to Technical Configuration 1, the exposed portion includes a first surface to be bonded to the wire and a second surface opposite to the first surface, and the identification mark is formed on at least the first surface.

[0067] Technical Configuration 3: In the electrode plate according to Technical Configuration 1, the exposed portion includes a first surface to be bonded to the wire and a second surface opposite to the first surface, and the identification mark is formed on at least the second surface.

[0068] Technical Configuration 4: According to the electrode plate of Technical Configuration 1, the identification mark is formed in a range that does not overlap with a joint portion between the core body and the lead wire in a thickness direction of the electrode plate.

[0069] Technical configuration 5: In the electrode plate according to any one of technical configurations 1 to 4, the identification mark is entirely formed within the projection range of the exposed portion.

[0070] Technical Configuration 6: A battery comprising an electrode body including the electrode plate according to any one of Technical Configurations 1 to 5, and an exterior body housing the electrode body.

[0071] Description of Reference Numerals

[0072] 10 cylindrical battery, 11 positive electrode plate, 12 negative electrode plate, 13 separator, 14 electrode body, 16 outer can, 17 sealing body, 18, 19 insulating plate, 20 positive electrode lead, 21 negative electrode lead, 22 groove, 23 internal terminal plate, 24 lower valve body, 25 insulating component, 26 upper valve body, 27 cover, 28 gasket, 30 positive electrode core, 31 positive electrode mixture layer, 32, 42 exposed part, 33, 34, 43 belt, 35, 45 joint part, 36, 46 identification mark, 40 negative electrode core, 41 negative electrode mixture layer, 100, 101 conveyor roller, X, Y projection range

Claims

1. An electrode plate comprising a core body and a mixture layer formed on the core body, and having an exposed portion exposing a surface of the core body, The electrode plate has a lead wire connected to the exposed portion and an identification mark. At least a portion of the identification mark is formed within a projection range of an outline of the lead projected onto the exposed portion.

2. The electrode plate according to claim 1, The exposed portion includes a first surface to be bonded to the wire and a second surface opposite to the first surface. The identification mark is formed at least on the first surface.

3. The electrode plate according to claim 1, The exposed portion includes a first surface to be bonded to the wire and a second surface opposite to the first surface. The identification mark is formed at least on the second surface.

4. The electrode plate according to claim 1, The identification mark is formed in a range that does not overlap with a joining portion between the core body and the lead wire in a thickness direction of the electrode plate.

5. The electrode plate according to claim 1, The identification mark is entirely formed within the projection range of the exposed portion. 6 . A battery comprising an electrode body including the electrode plate according to claim 1 , and an exterior body accommodating the electrode body.

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