Sealed battery

Abstract

A sealed battery according to one embodiment of the present invention comprises: an electrode body (14) in which a positive electrode plate (11) and a negative electrode plate (12) are stacked with a separator (13) interposed therebetween; an outer packaging body that houses the electrode body and has an opening at one end; and a sealing body (19) that seals the opening of the outer packaging body. The sealing body has an identification display (30) formed on a portion that can move away from the exterior body when the internal pressure of the battery rises.

Description

Technical Field

[0001] The present invention relates to a sealed battery. Background Art

[0002] Sealed batteries equipped with identification displays are known (see, for example, Patent Documents 1 and 2). This identification display can be used to identify the battery's production line, manufacturing date, and time. For example, if a battery experiences a problem during the manufacturing process or after shipment, this identification display can be used to analyze the cause.

[0003] Patent Document 1 describes providing an identification barcode (identification display) on the outer circumference or end surface of a battery can. Patent Document 2 describes providing an identification code (identification display) on a sealing member that closes the opening of a prismatic secondary battery having a prismatic outer casing at a position different from that of a gas discharge valve.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application No. 2015-524142

[0007] Patent Document 2: Japanese Patent Application Publication No. 2019-29189 Summary of the Invention

[0008] When an identification display is provided on the outer circumferential surface of the battery can, as in the configuration described in Patent Document 1, during the manufacturing process of a battery module comprising multiple batteries and a battery holder, the identification display may be damaged by contact between the battery holder and other components on the outer circumferential surface of the battery. This may make it difficult to read the identification display. In addition, when an identification display is provided on the outer circumferential surface, end surface, or seal of the battery at a position different from the gas discharge valve during abnormal heating of the battery, the identification display may also change color or deform due to the high temperature of the battery, making it difficult to read the identification display.

[0009] The sealed battery of the present invention comprises: an electrode body formed by stacking positive and negative plates with a separator therebetween, an outer packaging body that houses the electrode body and has an opening at one end, and a sealing body that seals the opening of the outer packaging body, wherein the sealing body has an identification display formed on a portion that can move away from the outer packaging body when the internal pressure of the battery increases.

[0010] The sealed battery of the present invention allows for an identification display to be provided in a portion of the seal that is less likely to come into contact with other components during the manufacturing process of the battery module containing the battery and that moves away from the battery before being exposed to high temperatures during abnormal heating. This facilitates reading of the identification display both after the battery is assembled into a battery module and after abnormal heating. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 This is a diagram schematically showing an axial cross section of a cylindrical battery used as a sealed battery as an example of an embodiment.

[0012] Figure 2 (a) Observed from the side Figure 1 Schematic diagram of a cylindrical battery, (b) is a view of part A of (a) viewed from above.

[0013] Figure 3 (a) means Figure 1 Schematic diagram of a state in which the valve portion of the sealing body is blown away by the increase in the internal pressure of the battery during abnormal heating of a cylindrical battery. (b) is a diagram showing the outer side surface of the valve portion shown in part B of (a).

[0014] Figure 4 Yes Figure 3 Schematic diagram of the state where the temperature rise of the cylindrical battery further advances after the state (a).

[0015] Figure 5 In a cylindrical battery as another example of a sealed battery, Figure 2 (b) Corresponding graph.

[0016] Figure 6 This is a schematic diagram showing a state in which a rupture plate of a sealing member ruptures during abnormal heat generation, thereby deforming the valve portion so as to move outward, in another example of the embodiment. DETAILED DESCRIPTION

[0017] Below, an embodiment of the sealed battery of the present invention is described in detail with reference to the accompanying drawings. The embodiment described below is merely an example, and the present invention is not limited to the following embodiment. In addition, the present invention also includes forms in which the components of the embodiments described below are selectively combined.

[0018] Hereinafter, a cylindrical battery 10 is described as an example of a sealed battery, wherein a wound electrode assembly 14 is housed in a bottomed cylindrical outer can 20. However, the outer can of the battery is not limited to a cylindrical outer can. For example, the sealed battery of the present invention may also be a prismatic battery having a prismatic outer can.

[0019] Figure 1 1 is a diagram schematically showing an axial cross section of a cylindrical battery 10 used as a sealed battery as an example of an embodiment. Figure 1 As shown, the cylindrical battery 10 includes an electrode body 14, an electrolyte, and an outer can 20 for housing 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. The positive electrode plate 11 and the negative electrode plate 12 are stacked with the separator 13 interposed therebetween and wound into a spiral shape. The outer can 20 is a metal container with a bottom and a cylindrical shape, with an opening at one axial end. The opening of the outer can 20 is sealed by a sealing member 19. For ease of description, the sealing member 19 side of the cylindrical battery 10 is referred to as the top, and the bottom side of the outer can 20 is referred to as the bottom.

[0020] The electrolyte may be an aqueous electrolyte, but in this embodiment, a non-aqueous electrolyte is used. The non-aqueous electrolyte includes a non-aqueous solvent and an electrolyte salt dissolved in the non-aqueous solvent. Examples of non-aqueous solvents include esters, ethers, nitriles, amides, and mixed solvents of two or more thereof. Examples of non-aqueous solvents include ethylene carbonate (EC), ethyl methyl carbonate (EMC), dimethyl carbonate (DMC), diethyl carbonate (DEC), and mixed solvents thereof. The non-aqueous solvent may contain a halogen-substituted substance (e.g., fluoroethylene carbonate) in which at least a portion of the hydrogen atoms of these solvents are replaced with halogen atoms such as fluorine. Examples of electrolyte salts include lithium salts such as LiPF6.

[0021] The positive electrode plate 11, negative electrode plate 12, and separator 13 that make up the electrode assembly 14 are all long, ribbon-like strips, wound in a spiral and stacked radially along the electrode assembly 14. To prevent lithium precipitation, the negative electrode plate 12 is slightly larger than the positive electrode plate 11. In other words, the negative electrode plate 12 is longer in both the length and width (short-side direction) than the positive electrode plate 11. The separator 13 is at least slightly larger than the positive electrode plate 11, and two separators are positioned to sandwich the positive electrode plate 11.

[0022] The positive electrode plate 11 has a positive electrode core and a positive electrode mixture layer formed on the positive electrode core. The positive electrode core can be made of a foil of a metal such as aluminum or aluminum alloy that is stable in the potential range of the positive electrode plate 11, or a film having the metal configured on the surface. The positive electrode mixture layer 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 preferably formed on both sides of the positive electrode core. A positive electrode mixture slurry containing a positive electrode active material, a conductive agent, and a binder is applied to both sides of the positive electrode core and the coating is compressed to produce the positive electrode plate 11.

[0023] An example of a positive electrode active material contained in the positive electrode mixture layer is a lithium transition metal composite oxide. A 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 elements constituting the composite oxide are, for example, at least one selected from the group consisting of Mg, Al, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Ge, Y, Zr, Sn, Sb, W, Pb, and Bi. Among these, at least one selected from the group consisting of Ni, Mn, and Co is preferably contained.

[0024] The negative electrode plate 12 includes a negative electrode core and a negative electrode mixture layer formed on the negative electrode core. The negative electrode core can 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 film having the metal disposed on the surface. The negative electrode mixture layer contains a negative electrode active material, a binder, and, if necessary, a conductive agent such as carbon black or carbon nanotubes, and is preferably formed on both sides of the negative electrode core. For example, styrene-butadiene rubber (SBR) can be used as the binder, and carboxymethyl cellulose or its salt can also be used in combination. The negative electrode mixture slurry containing the negative electrode active material and the binder is applied to both sides of the negative electrode core and the coating is compressed to produce the negative electrode plate 12.

[0025] An example of the negative electrode active material contained in the negative electrode mixture layer is a carbon material such as graphite that reversibly occludes and releases lithium ions. The 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 such elements, etc. can be used. Among them, composite materials containing Si are preferred. As a suitable 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 with ion permeability and insulation. Specific examples of the porous sheet include microporous films, woven fabrics, non-woven fabrics, and the like. Suitable materials for the separator 13 include polyolefins such as polyethylene and polypropylene, and cellulose. The separator 13 may be a single-layer structure or a multi-layer structure. In addition, a resin layer with high heat resistance such as an aromatic polyamide resin may be formed on the surface of the separator 13. A filler layer containing an inorganic filler may be formed at 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 15 and 16 are disposed above and below the electrode body 14 , respectively. Figure 1In the example shown, the positive electrode lead 17 extends through a through-hole in the insulating plate 15 toward the sealing body 19, while the negative electrode lead 18 extends through the outside of the insulating plate 16 toward the bottom 20a of the outer can 20. The positive electrode lead 17 is connected to the lower surface of an internal terminal plate 21 of the sealing body 19 by laser welding or other means. A rupture plate 22 (described later) serving as the top plate of the sealing body 19 and electrically connected to the internal terminal plate 21 serves as the positive electrode terminal. The negative electrode lead 18 is connected to the inner surface of the bottom 20a of the outer can 20 by laser welding or other means, with the outer can 20 serving as the negative electrode terminal.

[0028] The positive electrode lead 17 is bonded to the positive electrode core by ultrasonic welding or the like. For example, the positive electrode lead 17 is bonded to the longitudinal center of the positive electrode plate 11, spaced from both longitudinal ends. The positive electrode lead 17 can be bonded to positions substantially equidistant from both longitudinal ends of the positive electrode plate 11. The negative electrode lead 18 is bonded to the negative electrode core by ultrasonic welding or the like. Figure 1 In the example shown, a negative electrode lead 18 is joined to the winding end of the negative electrode plate 12, which is located on the outer periphery of the electrode body 14. The positive and negative electrode leads 17 and 18 are, for example, strip-shaped metal members having a thickness of 30 to 100 μm.

[0029] The negative electrode plate 12 may be disposed on the outer circumference of the electrode body 14. Alternatively, an exposed portion may be formed on the outer circumference of the electrode body 14, exposing the surface of the negative electrode core. This exposed portion may also be in contact with the inner surface of the outer can 20, electrically connecting the negative electrode plate 12 to the outer can 20. In this case, the negative electrode plate 12 may not have the negative electrode lead 18.

[0030] As described above, the outer can 20 is a metal container with a bottomed cylindrical shape and an opening at one axial end. A resin gasket 24 is provided between the outer can 20 and the sealing body 19 to ensure the airtightness of the battery interior and the insulation between the outer can 20 and the sealing body 19. The outer can 20 has a groove 20b formed on the side surface thereof, which bulges inward and supports the sealing body 19. The groove 20b is preferably formed in an annular shape along the circumferential direction of the outer can 20, and the sealing body 19 is supported by its upper surface. The sealing body 19 is fixed to the upper portion of the outer can 20 by using the groove 20b and the open end of the outer can 20 that is crimped to the sealing body 19.

[0031] The sealing member 19 is a disc-shaped member equipped with a current interruption mechanism. The sealing member 19 comprises an internal terminal plate 21, an insulating plate 23, and a rupture plate 22 stacked in this order from the electrode body 14 side. The internal terminal plate 21 has a thinner portion at its center than the outer annular portion connected to the positive electrode lead 17.

[0032] Insulating plate 23 is a disc-shaped member made of insulating material with an opening 23a at its center. Rupturable plate 22 is positioned opposite internal terminal plate 21, sandwiching insulating plate 23. The center of rupturable plate 22 is connected to the thin-walled center portion of internal terminal plate 21 by welding or other means through opening 23a in insulating plate 23.

[0033] In addition, the rupture plate 22 has an easily breakable portion 22a in the radial middle portion. The easily breakable portion 22a is formed by an annular thin-walled portion 22b formed in a radial portion of the rupture plate 22. Figure 1 The groove for forming the easy-to-break portion 22a may also be formed on the outer side surface ( Figure 1 The valve portion 22d is formed by utilizing a portion of the rupture plate 22 that is radially inward of the easily breakable portion 22a.

[0034] The sealing member 19 is secured to the outer can 20 by crimping, via a gasket 24, radially outward of the easily breakable portion 22a. The pressure within the battery acts on the groove 22c of the rupture plate 22 through the vent holes formed in the internal terminal plate 21 and the insulating plate 23.

[0035] When the internal pressure of the battery rises and exceeds a predetermined threshold, the easily breakable portion 22 a of the rupture plate 22 breaks, and the valve portion 22 d radially inward of the easily breakable portion 22 a moves away from the outer can 20 .

[0036] In the cylindrical battery 10, the electrical connection between the internal terminal plate 21, to which the positive lead 17 is connected, and the rupture plate 22 forms a current path from the electrode body 14 to the rupture plate 22. When an abnormality occurs in the battery and the internal pressure rises, the internal terminal plate 21 breaks, separating the thin-walled portion of the internal terminal plate 21 from the annular portion outside it, and the valve portion 22d deforms convexly toward the outside of the battery. This blocks the current path. When the internal pressure of the battery rises further, the easily breakable portion 22a breaks as described above, forming a gas discharge port. If the easily breakable portion 22a breaks across its entire circumference, the valve portion 22d is blown out of the battery. If only a portion of the circumferential portion of the easily breakable portion 22a breaks, leaving a portion of the circumferential portion of the valve portion 22d bonded to the remaining portion of the rupture plate 22, the valve portion 22d deforms to move outward. In either case, the valve portion 22d is capable of moving away from the outer can 20 when the internal pressure of the battery rises.

[0037] On the outer side of the rupture plate 22, Figure 1 The portion of the area indicated by arrow α forms the identification display 30 . Figure 2(a) is a schematic diagram of a cylindrical battery 10 viewed from the side. Figure 2 (b) Observation from above Figure 2 (a) Diagram of part A.

[0038] like Figure 2 As shown in (b), the sealing member 19 includes an identification indicator 30 formed on the outer side of the valve portion 22d, radially inward of the easily breakable portion 22a. The identification indicator 30 is preferably formed away from the center of the valve portion 22d to avoid the connection point of the external lead provided on the positive terminal plate (not shown) to the rupture plate 22.

[0039] The identification display 30 is an independent display attached to the cylindrical battery 10, providing identification information for distinguishing it from other cylindrical batteries 10. A different identification display 30 is provided for each cylindrical battery 10, or for each group of a predetermined number of cylindrical batteries 10. The identification display 30 may be a batch number attached to a group of products manufactured at the same time, or a product number attached to each individual product.

[0040] The identification display 30 allows individual cylindrical batteries 10 or individual manufacturing batches to be distinguished and is used to obtain information about the manufacturing of the cylindrical batteries 10. For example, the manufacturer of the cylindrical batteries 10 may have a database containing information about the manufacturing of the cylindrical batteries 10, which is associated with the identification display 30 of the cylindrical batteries 10. Therefore, by reading the identification display 30 using a reader or other device and identifying the cylindrical battery 10, information about the manufacturing of the cylindrical battery 10 can be obtained. An example of information about the manufacturing of the cylindrical batteries 10 is a history of the manufacturing process including information such as the production line and the date and time of manufacturing.

[0041] The identification display 30 includes, for example, at least one selected from the group consisting of numbers, characters, and identification codes. The identification display 30 may also be a combination of numbers and characters. The identification code constituting the identification display 30 may be any one of a one-dimensional code, a two-dimensional code, and a three-dimensional code, but is preferably a two-dimensional code. Figure 2 In the example shown, a square two-dimensional code (QR code (registered trademark)) is formed as the identification display 30 .

[0042] The identification mark 30 can be read using a reader or other reading device and may include at least one selected from a protrusion and a depression. Alternatively, the identification mark 30 may have a color different from the surrounding area. The numbers, characters, or identification code constituting the identification mark 30 may not have protrusions or depressions, but may simply have a color different from the surrounding area.

[0043] The identification display 30 can be formed by printing such as inkjet printing, or by pressing, but is preferably formed by laser marking. Laser marking is a method of forming a display by irradiating the valve portion 22d with laser light. In the case where the identification display 30 is a laser marking display, the display is formed, for example, by discoloring the portion irradiated with laser light. In addition, a depression can be formed in the portion irradiated with laser light. Since the laser marking display has excellent durability, it is less likely to cause poor reading after the cylindrical battery 10 has been used.

[0044] According to the cylindrical battery 10 described above, the seal 19 includes an identification indicator 30 formed in a portion that can move away from the outer can 20 when the battery internal pressure rises. This prevents contact with other components during the manufacturing process of the battery module containing the battery. Furthermore, the identification indicator 30 is provided in a portion of the seal 19 that can move away from the battery before exposure to high temperatures during abnormal heating. Consequently, the identification indicator can be easily read both after the battery is assembled into a battery module and after abnormal heating.

[0045] Figure 3 (a) is a schematic diagram showing a state in which the valve portion 22d of the sealing member 19 is blown away by the increase in the internal pressure of the battery when the cylindrical battery 10 is abnormally heated. Figure 3 (b) means Figure 3 (a) is a diagram showing the outer side surface of the valve portion 22d shown in part B.

[0046] Figure 3 In FIG. 1 , it is shown that the easily breakable portion 22 a ( Figure 1 、 Figure 2 ) is broken in the entire circumferential direction and the valve portion 22d is blown outward. Figure 3 As shown in (b), the identification display 30 is maintained on the blown-off valve portion 22d.

[0047] Figure 4 This is a schematic diagram showing a state where the temperature rise of the cylindrical battery 10 further advances thereafter. Figure 4 In the figure, the dotted line indicates that a large amount of heat is generated locally in the upper portion of the cylindrical battery 10. For example, if the cylindrical battery 10 is used under extremely harsh conditions or if excessive external force is applied, the possibility of ignition and localized large amounts of heat generation is not zero. In this case, the valve portion 22d on which the identification display is formed may separate from the cylindrical battery 10 and fall to the surrounding area before such a large amount of heat is generated. This can prevent the thermal effects of the cylindrical battery 10 from affecting the identification display 30, causing discoloration or deformation that makes the display difficult to read.

[0048] In the above embodiment, the identification display 30 is formed on the outer side of the valve portion 22d. However, the identification display can also be formed on the inner side of the valve portion 22d. On the other hand, from the aspect of the easy formation of the identification display 30, it is preferred to Figures 1 to 4 As in the embodiment of FIG. 1 , the identification display 30 is formed on the outer side surface of the valve portion 22 d.

[0049] Figure 5 In another embodiment, the cylindrical battery 10a is Figure 2 (b) Corresponding graph. Figure 6 This is a schematic diagram showing a state in which the rupture plate 32 of the sealing body 19a is ruptured during abnormal heat generation, causing the valve portion 32d to deform so as to move outward in another example of the embodiment.

[0050] In this embodiment, the thin-walled portion 32b of the rupture plate 32, which forms the easily breakable portion 32a, is provided in a C-shape on the inner side of the rupture plate 32, rather than extending along the entire circumference. The valve portion 32d of the rupture plate 32 is formed radially inward of the easily breakable portion 32a. The identification indicator 30 is formed on the outer side of the valve portion 32d, radially inward of the easily breakable portion 32a.

[0051] In the configuration of this example, when the cylindrical battery 10a is abnormally heated, Figure 6 As shown, due to the increase in the internal pressure of the battery, the easily breakable portion 32a breaks to form a gas discharge port. In a state where the valve portion 22d is connected to the remaining periphery of the rupture plate 32 at the discontinuous portion in the circumferential direction of the easily breakable portion 32a due to the break, the valve portion 22d moves toward the outside of the battery in a manner away from the outer packaging can 20. Thus, thereafter, even when the temperature of the cylindrical battery 10 further rises, it is possible to suppress the temperature of the valve portion 22d that is deformed outward from increasing. Therefore, it is possible to suppress the thermal influence of the cylindrical battery 10 from affecting the identification display 30 and making it difficult to read the display due to discoloration or deformation. In this example, the other structures and functions are the same as Figures 1 to 4 The composition is the same.

[0052] Description of Reference Numerals

[0053] 10, 10a Cylindrical battery, 11 Positive electrode plate, 12 Negative electrode plate, 13 Separator, 14 Electrode body, 15, 16 Insulating plate, 17 Positive electrode lead, 18 Negative electrode lead, 19 Sealing member, 20 Outer can, 20a Bottom, 20b Grooved portion, 21 Internal terminal plate, 22 Rupture plate, 22a Easy-to-break portion, 22b Thin-walled portion, 22c Groove, 22d Valve portion, 23 Insulating plate, 23a Opening, 24 Gasket, 30 Identification display, 32 Rupture plate, 32a Easy-to-break portion, 32b Thin-walled portion, 32d Valve portion.

Claims

1. A sealed battery comprising: The positive electrode plate and the negative electrode plate are stacked with a separator between them. an outer packaging body that houses the electrode body and has an opening at one end, and a sealing body for sealing the opening of the outer packaging body, The sealing body has an identification indicator formed on a portion that is movable away from the outer packaging body when the internal pressure of the battery increases.

2. The sealed battery according to claim 1, wherein The sealing body has an annular or C-shaped easily breakable portion, and is fixed to the outer packaging body by crimping at a position radially outward of the easily breakable portion via a resin gasket. The identification display is formed radially inward of the easy-to-break portion.

3. The sealed battery according to claim 2, wherein: The easily breakable portion is formed of a thin-walled portion.

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