Cylindrical battery

Abstract

This cylindrical battery comprises an electrode body in which a positive electrode and a negative electrode are wound with a separator interposed therebetween, an electrolyte, a bottomed cylindrical outer can accommodating the electrode body and the electrolyte, and a sealing body blocking an opening portion of the outer can, wherein: the sealing body has a cap disposed in the outermost portion of the sealing body; the cap includes a protruding portion formed in a central portion thereof; the protruding portion includes a top surface portion and a side wall portion; and a plurality of independent venting ports are formed in the top surface portion and the side wall portion.

Description

Technical Field

[0001] The present disclosure relates to a cylindrical battery.

Background Art

[0002] Conventionally, a cylindrical battery having a bottomed cylindrical outer can and a sealing body that closes the opening of the outer can is known. Further, the cylindrical battery may be used as an assembled battery (battery pack) in which a plurality of cylindrical batteries are connected.

[0003] In the case of a cylindrical battery, cases have been reported in which ignition occurs during an abnormality. When the cylindrical battery catches fire, flames may spout from the exhaust port of the cylindrical battery, and there is a risk that adjacent cylindrical batteries in the battery pack will burn. Patent Document 1 discloses a battery pack in which a mesh member for extinguishing the flames spouting from the exhaust port of the cylindrical battery is disposed above the cylindrical battery. Further, Patent Document 2 discloses a configuration in which a fire extinguishing agent is provided in the battery pack.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

[0005] In the battery packs disclosed in Patent Documents 1 and 2, since the fire extinguishing components are arranged as separate components, the cost increases by the number of components compared to a normal battery pack. Further, in the above battery pack, since the fire extinguishing components are arranged, it is difficult to miniaturize the battery pack, and as a result, it is also difficult to miniaturize the device incorporating the battery pack.

[0006] A cylindrical battery according to one aspect of the present disclosure includes an electrode body in which a positive electrode and a negative electrode are wound with a separator interposed therebetween, an electrolyte, a bottomed cylindrical outer can that houses the electrode body and the electrolyte, and a sealing body that closes the opening of the outer can. The sealing body has a cap disposed on the outermost part of the sealing body. The cap includes a convex portion formed at the center. The convex portion includes a top surface portion and a side wall portion. Independent exhaust ports are formed in the top surface portion and the side wall portion, respectively.

[0007] According to one aspect of the present disclosure, when ignition occurs during an abnormality, the battery unit can extinguish the fire.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Embodiments for Carrying Out the Invention

[0009] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. The shapes, materials, and numbers described below are examples for explanation and can be appropriately changed according to the specifications of the cylindrical battery. Hereinafter, the same reference numerals will be given to equivalent elements in all the drawings for explanation.

[0010] A cylindrical battery 10 which is an example of the present embodiment will be described with reference to FIG. 1. FIG. 1 is a cross-sectional view of the cylindrical battery 10.

[0011] As shown in FIG. 1, the cylindrical battery 10 has an electrode body 14, an electrolyte, and an exterior can 16 that houses the electrode body 14 and the electrolyte. The electrode body 14 has a positive electrode 11, a negative electrode 12, and a separator 13, and has a winding structure in which the positive electrode 11 and the negative electrode 12 are wound in a spiral shape with the separator 13 interposed therebetween. The exterior can 16 has a bottomed cylindrical shape with one axial side open, and the opening of the exterior can 16 is closed by a sealing body 17.

[0012] The positive electrode 11 has a positive electrode current collector and a positive electrode composite layer formed on at least one surface of the current collector. For the positive electrode current collector, a foil of a metal stable within the potential range of the positive electrode 11, such as aluminum or an aluminum alloy, or a film with such a metal disposed on the surface layer can be used. The positive electrode composite layer includes a positive electrode active material, a conductive material such as acetylene black, and a binder material such as polyvinylidene fluoride, and is preferably formed on both surfaces of the positive electrode current collector. For the positive electrode active material, for example, a lithium-containing transition metal composite oxide is used. The positive electrode 11 can be manufactured by applying a positive electrode composite slurry containing a positive electrode active material, a conductive material, a binder material, etc. onto the positive electrode current collector, drying the coating film, and then compressing the coating film to form the positive electrode composite layer on both surfaces of the positive electrode current collector.

[0013] The negative electrode 12 has a negative electrode current collector and a negative electrode composite layer formed on at least one surface of the current collector. For the negative electrode current collector, a foil of a metal stable within the potential range of the negative electrode 12, such as copper or a copper alloy, or a film with such a metal disposed on the surface layer can be used. The negative electrode composite layer includes a negative electrode active material and a binder material such as styrene-butadiene rubber (SBR), and is preferably formed on both surfaces of the negative electrode current collector. For the negative electrode active material, for example, graphite, a silicon-containing compound, etc. are used. The negative electrode 12 can be manufactured by applying a negative electrode composite slurry containing a negative electrode active material, a binder material, etc. onto the negative electrode current collector, drying the coating film, and then rolling the coating film to form the negative electrode composite layer on both surfaces of the current collector.

[0014] For the electrolyte, for example, 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. As the non-aqueous solvent, for example, esters, ethers, nitriles, amides, a mixed solvent of two or more of these, etc. may be used. The non-aqueous solvent may contain a halogen-substituted product in which at least a part of the hydrogen of these solvents is substituted with a halogen atom such as fluorine. Note that the non-aqueous electrolyte is not limited to a liquid electrolyte and may be a solid electrolyte. As the electrolyte salt, for example, a lithium salt such as LiPF6 is used. The type of the electrolyte is not particularly limited and may be an aqueous electrolyte.

[0015] The cylindrical battery 10 has insulating plates 18 and 19 respectively arranged above and below the electrode body 14. In the example shown in FIG. 1, the positive electrode lead 20 attached to the positive electrode 11 extends toward the sealing body 17 through the through hole of the insulating plate 18, and the negative electrode lead 21 attached to the negative electrode 12 extends toward the bottom side of the outer can 16 through the outside of the insulating plate 19. The positive electrode lead 20 is connected by welding or the like to the bottom surface of the internal terminal plate 23 arranged at the innermost part of the sealing body 17. Thereby, the cap 30 which is the top plate of the sealing body 17 electrically connected to the internal terminal plate 23 becomes the positive electrode external terminal. The negative electrode lead 21 is connected by welding or the like to the inner surface of the bottom of the outer can 16. Thereby, for example, the bottom of the outer can 16 becomes the negative electrode external terminal.

[0016] The outer can 16 is a bottomed cylindrical metal container. A gasket 27 is provided between the outer can 16 and the sealing body 17 to ensure the airtightness inside the battery. The outer can 16 is formed with a groove portion 22 for supporting the sealing body 17, in which a part of the side surface portion projects inward. The groove portion 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 by the groove portion 22 and the open end portion of the outer can 16 caulked to the sealing body 17. An annular caulking portion 28 is formed at the open end portion of the outer can 16.

[0017] The sealing body 17 has a structure in which an internal terminal plate 23, a lower valve body 24, an insulating member 25, an upper valve body 26, and a cap 30 are laminated in this order from the side of the electrode body 14. Each member constituting the sealing body 17 has, for example, a disk shape or a ring shape, and each member except the insulating member 25 is electrically connected to each other. The lower valve body 24 and the upper valve body 26 are connected to each other at their respective central portions, and the insulating member 25 is interposed between the peripheral portions of each. When the internal pressure of the cylindrical battery 10 rises during abnormal occurrence, the lower valve body 24 is deformed and broken so as to push up the upper valve body 26 toward the cap 30 side, and the current path between the lower valve body 24 and the upper valve body 26 is interrupted. When the internal pressure further rises, the upper valve body 26 is broken, and gas is discharged from exhaust ports 33H and 34H of the cap 30 described later.

[0018] Note that the structure of the sealing body is not limited to the structure illustrated in FIG. 1. For example, the sealing body may have a structure without an internal terminal plate, or an electrode lead may be connected to the lower valve body. Further, the valve body may be composed of one member.

[0019] Another example of the internal terminal plate 23 constituting the sealing body 17 will be described with reference to FIG. 2. FIG. 2 is a perspective view showing the internal terminal plate 23.

[0020] As described above, the internal terminal plate 23 is disposed at the innermost part of the sealing body 17. A positive electrode lead 20 is connected to the lower surface of the internal terminal plate 23 by welding or the like (see FIG. 1). As shown in FIG. 2, the internal terminal plate 23 includes a recess 23A formed in the central portion of the metal plate and an outer peripheral portion 23B formed around the recess 23A. The recess 23A bulges inside the cylindrical battery 10. A plurality of exhaust ports 23H are formed in the recess 23A. The exhaust ports 23H have, for example, the same diameter as the exhaust ports 33H on the top surface 33 of the cap 30 described later.

[0021] According to the internal terminal board 23, when ignition occurs during an abnormality, the recess 23A can block the flame and suppress the ejection of the flame. Further, according to the internal terminal board 23, by absorbing heat from the ejected flame by the recess 23A, the temperature of the flame can be lowered, and the ejection of the flame can be suppressed. Furthermore, in the internal terminal board 23, since a plurality of exhaust ports 23H are formed in the recess 23A, the gas generated inside the cylindrical battery 10 during an abnormality can easily escape to the outside.

[0022] Using FIG. 3, the cap 30 constituting the sealing body 17 will be described. FIG. 3 is a perspective view showing the cap 30.

[0023] The cap 30 is disposed at the outermost part of the sealing body 17 and forms the top surface of the cylindrical battery 10. The cap 30 is, for example, a welding terminal on the positive electrode side for connecting cylindrical batteries 10 in series or in parallel or for attaching a safety element to the cylindrical battery 10 when incorporating the cylindrical battery 10 into a device.

[0024] As shown in FIG. 3, the cap 30 is formed in a substantially disk shape. Further, the cap 30 is formed of a metal plate. The composition of the metal plate is not particularly limited, but is generally iron or an iron alloy (for example, stainless steel). An example of the thickness of the metal plate is 0.1 mm to 0.8 mm. The cap 30 is manufactured, for example, by deep drawing a metal plate. The cap 30 includes a convex portion 31 formed at the central portion of the metal plate and a flange portion 32 formed around the convex portion 31.

[0025] The convex portion 31 bulges outside the cylindrical battery 10. Although the convex portion 31 of the present embodiment bulges outside the cylindrical battery 10, the convex portion may bulge inside the cylindrical battery 10. The degree (height) of the bulge of the convex portion 31 is not particularly limited, but is, for example, about 1 mm to 5 mm. The convex portion 31 is preferably formed such that the center of the top surface portion 33 coincides with the center in the radial direction of the cap 30 in a plan view. The convex portion 31 includes a top surface portion 33 and a side wall portion 34 connected to the flange portion 32.

[0026] The top surface portion 33 is a portion where, as will be described in detail later, when ignition occurs during an abnormality in the cylindrical battery 10, the flame is blocked, and as described above, is a portion where the lead wire or the like is connected by welding or the like. The top surface portion 33 is formed in a substantially circular shape in plan view. The top surface portion 33 is flat and is formed parallel to the flange portion 32. It is not necessary for the entire top surface portion 33 to be flat. For example, the outer peripheral portion may be chamfered. The top surface portion 33 is preferably formed as wide as possible in consideration of the flame blocking effect when ignition occurs during an abnormality in the cylindrical battery 10 described above, the workability of the welding joint, the welding strength, and the like.

[0027] A plurality of exhaust ports 33H are formed in the outer peripheral portion of the top surface portion 33. In the example shown in FIG. 3, a plurality of exhaust ports 33H are formed in an annular shape along the circumferential direction at substantially equal intervals for one turn. The exhaust port 33H is preferably a perfect circle in plan view, but may be, for example, a polygon, an ellipse, a substantially circular shape, or the like. The exhaust port 33H is preferably formed together with the exhaust port 34H described later, for example, before the cap 30 is manufactured by deep drawing.

[0028] The exhaust port 33H has a diameter of 0.01 mm to 9 mm, preferably a diameter of 0.5 mm to 3 mm. In the example shown in FIG. 2, the diameter of the exhaust port 33H is 1 mm. Also, it is preferable that at least the diameters of the exhaust ports 33H formed in the top surface portion 33 have substantially the same diameter, but they may be different from each other. The total opening area of the exhaust ports 33H is 1 to 30 mm 2 and more preferably 5 to 15 mm 2 and is formed to be so. In the example shown in FIG. 2, the total opening area of the exhaust ports 33H is 9 mm 2 and is.

[0029] The total opening ratio of all the exhaust ports 33H in the top surface portion 33 is 1 to 60%, preferably 10 to 30%. The total opening ratio is the ratio of the total opening area of all the exhaust ports 33H to the surface area of the top surface portion 33. In the example shown in FIG. 3, the total opening ratio of the exhaust ports 33H is 24%.

[0030] The central portion of the top surface portion 33 has a flat top surface without the formation of the exhaust port 33H. According to the central portion of the top surface portion 33, the workability during welding can be improved, and the welding strength and the like can be improved. The central portion of the top surface portion 33 may be formed with the exhaust port 33H in the manufacturing process of the cap 30, and the exhaust port 33H may be blocked by the lead wire and the welded portion when the lead wire is welded.

[0031] The side wall portion 34 is a portion connecting the flange portion 32 and the top surface portion 33, and is formed substantially perpendicular to the flange portion 32. The angle formed by the side wall portion 34 with respect to the bulging direction of the convex portion 31 is preferably about 90° to 110°, and more preferably about 90° to 100°.

[0032] A plurality of exhaust ports 34H are formed in the side wall portion 34. The exhaust port 34H is preferably a perfect circle when viewed from a direction perpendicular to the side wall portion 34, but may be, for example, a polygon, an ellipse, a substantially circular shape, or the like. The exhaust port 34H is preferably formed together with the exhaust port 33H before the cap 30 is manufactured by deep drawing processing as described above.

[0033] The exhaust port 34H has a diameter of 0.01 mm to 9 mm, and preferably has a diameter of 0.5 mm to 2 mm. In the example shown in FIG. 2, the diameter of the exhaust port 34H is 0.5 mm. Further, it is preferable that at least the diameters of the exhaust ports 34H formed in the side wall portion 34 have substantially the same diameter, but they may be different from each other.

[0034] The total opening ratio of all the exhaust ports 34H in the side wall portion 34 is 1 to 60%, and preferably 10 to 30%. The total opening ratio is the ratio of the sum of the opening areas of all the exhaust ports 34H to the surface area of the side wall portion 34. Here, it is preferable that the total opening ratio of the exhaust port 33H in the top surface portion 33 described above is larger than the total opening ratio of the exhaust port 34H in the side wall portion 34.

[0035] In the convex portion 31 of the present embodiment, a plurality of independent exhaust ports 33H and 34H are formed in the top surface portion 33 and the flange portion 32, respectively, but exhaust ports may be formed at the boundary portion between the top surface portion 33 and the flange portion 32.

[0036] The cap 30 includes a flange portion 32 formed around the convex portion 31 as described above. Since the flange portion 32 is a portion pressed by the caulking portion 28 of the outer can 16, it is necessary to secure a flange portion 32 having a certain width. Further, exhaust ports may be formed in the flange portion 32.

[0037] The effects of the cylindrical battery 10 will be described. According to the cylindrical battery 10, the cylindrical battery 10 can extinguish ignition during abnormal times by itself.

[0038] In the cylindrical battery 10, ignition may occur when an abnormality occurs. In such ignition of the cylindrical battery 10, flames jet out from the exhaust portion formed by breaking of the upper valve body 26 of the cylindrical battery 10. In the cap 30 of the cylindrical battery 10, only a plurality of exhaust ports 33H and 34H are formed in the top surface portion 33 and the side wall portion 34 of the convex portion 31, and it does not have an opening of a size such that flames jet out as compared with a conventional cap in which a large exhaust port is formed in the side wall portion. Therefore, the top surface portion 33 and the side wall portion 34 can block the flames and suppress the jetting of the flames.

[0039] Further, in the cap 30 of the cylindrical battery 10 of the present embodiment, the top surface portion 33 and the side wall portion 34 of the convex portion 31 can absorb heat from the jetted flames to lower the temperature of the flames and suppress the jetting of the flames.

[0040] By the cylindrical battery 10 extinguishing ignition during abnormal times by itself, it is not necessary to arrange digestion components as separate components in a battery pack in which a plurality of cylindrical batteries 10 are packaged as in the prior art. Therefore, neither the cost due to an increase in the number of parts of the battery pack nor an increase in the number of parts occurs. Also, it is possible to miniaturize the cylindrical battery or the battery pack.

[0041] Furthermore, in the cap 30 of the cylindrical battery 10 of the present embodiment, since a plurality of exhaust ports 33H and 34H are formed in the top surface portion 33 and the side wall portion 34 of the convex portion 31, respectively, the gas generated inside the battery can be released to the outside. In the cap 30 of the cylindrical battery 10 of the present embodiment, a plurality of exhaust ports 33H are also formed in the top surface portion 33 of the convex portion 31. Compared with the conventional cap in which the exhaust port is formed only in the side wall portion, the configuration is such that it is easier to release the gas to the outside.

[0042] Using FIG. 4, another example of the cap 30 of the present embodiment will be described. FIG. 4 is a perspective view showing the cap 30.

[0043] As shown in FIG. 4, the cap 30 has the same configuration as the above-described cap 30 shown in FIG. 3, except that the diameters and numbers of the plurality of exhaust ports 33H formed in the top surface portion 33 are different. In the example shown in FIG. 4, the plurality of exhaust ports 33H are formed in an annular shape along the circumferential direction at substantially equal intervals for two rounds. In the example shown in FIG. 4, the exhaust port 33H has a diameter of 0.5 mm, and the total opening area of the exhaust ports 33H is 5 mm 2 and the total opening ratio of the exhaust ports 33H in the top surface portion 33 is 13%. Even the cap 30 shown in FIG. 4 exhibits the same effects as the above-described cap 30 shown in FIG. 3.

[0044] Note that the present invention is not limited to the above-described embodiments and their modifications, and it goes without saying that various changes and improvements can be made within the scope of the matters described in the claims of the present application.

Explanation of Reference Numerals

[0045] 10 Cylindrical battery 11 Positive electrode 12 Negative electrode 13 Separator 14 Electrode body 16 Outer can 17 Sealing body 18, 19 Insulating plate 20 Positive electrode lead 21 Negative electrode lead 22 Grooved portion 23 Inner terminal board 23A Recess 23B Outer peripheral part 23H Exhaust port 24 Lower valve body 25 Insulating member 26 Upper valve body 27 Gasket 30 Cap 31 Protrusion 32 Flange part 33 Top surface part 33H Exhaust port 34 Side wall part 34H Exhaust port

Claims

1. A cylindrical battery comprising: an electrode body in which a positive electrode and a negative electrode are wound with a separator interposed therebetween; an electrolyte; a bottomed cylindrical exterior can that houses the electrode body and the electrolyte; and a sealing body that closes an opening of the exterior can, wherein the sealing body has a cap disposed on the outermost portion of the sealing body, the cap includes a convex portion formed at a central portion, the convex portion includes a top surface portion and a side wall portion, a plurality of independent exhaust ports are respectively formed in the top surface portion and the side wall portion, the exhaust ports have a diameter of 0.01 mm to 9 mm, cylindrical battery.

2. The cylindrical battery according to claim 1, wherein a total opening ratio of the exhaust ports in the top surface portion is larger than a total opening ratio of the exhaust ports in the side wall portion. cylindrical battery.

3. The cylindrical battery according to claim 1 or 2, wherein the exhaust ports are not formed at a substantially central portion of the top surface portion. cylindrical battery.

4. The cylindrical battery according to any one of claims 1 to 3, wherein the sealing body has an internal terminal plate disposed at the innermost portion of the sealing body, to which a positive electrode lead is joined, and which forms a current path from the positive electrode lead to the cap, and a plurality of exhaust ports are formed in the internal terminal plate. cylindrical battery.

5. The cylindrical battery according to any one of claims 1 to 4, wherein the cap includes a flange portion formed around the convex portion, and a plurality of exhaust ports are formed in the flange portion. cylindrical battery.

Images