Cylindrical battery

Abstract

Provided is a cylindrical battery with which it is possible to suppress an increase in weight while increasing capacity.　A cylindrical battery (10) includes: an electrode body comprising a positive electrode and a negative electrode, which are wound together via a separator; an electrolyte; a bottomed cylindrical outer can (20) for accommodating the electrode body and the electrolyte; and a sealing body (30) that is fixed to an open end portion (20B) of the outer can (20) by swaging and is for sealing the outer can (20). In regard to the outer can (20), the outer diameter of a body part (20A) for accommodating the electrode body is 20 mm or greater, and the outer diameter of the open end portion (20B) for accommodating the sealing body (30) is less than the outer diameter of the body part (20A).

Description

[Technical field]

[0001] The present disclosure relates to cylindrical batteries. [Background technology]

[0002] Conventionally, cylindrical batteries have been known. For example, Patent Document 1 discloses a cylindrical battery having a cylindrical outer can with a bottom that is open at one end and a sealing body that seals the outer can. In recent years, the applications of cylindrical batteries have expanded from personal computers to electric vehicles and the like, so there is a demand for cylindrical batteries with a higher capacity, and studies are being conducted on increasing the size of the battery. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2018-200826 A Summary of the Invention [Problem to be solved by the invention]

[0004] In order to increase the size of the battery, if the diameter of the outer can is increased, the diameter of the sealing body must be increased. In order to increase the diameter of the sealing body, the crimping force when crimping the sealing body to the outer can and the durability of the sealing body against external impact must also be increased, and thus the thickness of the sealing body must be increased. However, if the thickness of the sealing body is increased, the weight of the sealing body increases, leading to an increase in the weight of the cylindrical battery.

[0005] An object of the present disclosure is to provide a cylindrical battery that can achieve high capacity while suppressing an increase in weight. [Means for solving the problem]

[0006] A cylindrical battery according to one embodiment of the present disclosure is a cylindrical battery having an electrode assembly in which a positive electrode and a negative electrode are wound with a separator interposed therebetween, an electrolyte, a cylindrical outer can with a bottom that houses the electrode assembly and the electrolyte, and a sealing body that is crimped and fixed to the open end of the outer can, wherein the outer diameter of the body of the outer can that houses the electrode assembly is 20 mm or more, and the outer diameter of the open end that houses the sealing body is smaller than the outer diameter of the body portion. Effect of the Invention

[0007] According to one aspect of the present disclosure, a cylindrical battery can be realized that can achieve a high capacity while suppressing an increase in weight. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a cross-sectional view of a cylindrical battery according to an embodiment. [Diagram 2] 1 is a cross-sectional view of an exterior can and a sealing body according to an embodiment of the present invention. [Diagram 3] FIG. 2 is a flow diagram showing a flow of a manufacturing process for manufacturing a cylindrical battery according to an embodiment. [Figure 4] 5A to 5C are schematic diagrams illustrating a part of a manufacturing process for manufacturing a cylindrical battery according to an embodiment of the present invention. [Diagram 5] 1A is a cross-sectional view of a cylindrical battery according to an embodiment of the present invention, and FIG. 1B is a cross-sectional view of a cylindrical battery according to a comparative example, illustrating the effects of the cylindrical battery according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, an embodiment of the present disclosure will be described with reference to the drawings. The shapes, materials, and numbers described below are examples for the purpose of explanation and can be changed as appropriate according to the specifications of the cylindrical battery. In the following, the same reference numerals are used to denote equivalent elements in all drawings.

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

[0011] 1, cylindrical battery 10 includes an electrode assembly 14, an electrolyte (not shown), and an exterior can 20 that accommodates the electrode assembly 14 and the electrolyte. The electrode assembly 14 includes a positive electrode 11, a negative electrode 12, and a separator 13, and has a wound structure in which the positive electrode 11 and the negative electrode 12 are wound in a spiral shape with separator 13 interposed therebetween. The exterior can 20 has a cylindrical shape with a bottom that is open at the top, and the opening of the exterior can 20 is closed by a sealing body 30.

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

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

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

[0015] The cylindrical battery 10 includes insulating plates 18, 19 disposed above and below the electrode body 14. In the example shown in Fig. 1, the positive electrode lead 15 attached to the positive electrode 11 passes through a through hole in the insulating plate 18 and extends toward the sealing body 30, and the negative electrode lead 16 attached to the negative electrode 12 passes outside the insulating plate 19 and extends toward the bottom side of the outer can 20. The positive electrode lead 15 is connected to the lower surface of the internal terminal plate 31, which is the bottom plate of the sealing body 30, by welding or the like, and the cap 35, which is the top plate of the sealing body 30 and is electrically connected to the internal terminal plate 31, serves as the positive electrode external terminal. The negative electrode lead 16 is connected to the inner surface of the bottom of the outer can 20 by welding or the like, and the bottom of the outer can 20 serves as the negative electrode external terminal.

[0016] The outer can 20 is a cylindrical metal container with a bottom. A gasket 39 is provided between the outer can 20 and the sealing body 30 to ensure the sealing of the inside of the battery. Although details will be described later, the outer diameter of the open end 20B of the outer can 20 is formed smaller than the outer diameter of the body portion 20A of the outer can 20 that houses the electrode body 14. A grooved portion 20C that supports the sealing body 30 is formed near the open end 20B of the outer can 20, with a part of the side portion protruding inward. The grooved portion 20C is preferably formed in an annular shape along the circumferential direction of the outer can 20, and supports the sealing body 30 on its upper surface. The sealing body 30 supported by the grooved portion 20C is fixed to the outer can 20 by the open end of the outer can 20 that is crimped to the sealing body 30.

[0017] The sealing body 30 has a structure in which an internal terminal plate 31, a lower valve body 32, an insulating member 33, an upper valve body 34, and a cap 35 are laminated in this order from the electrode body 14 side. Each member constituting the sealing body 30 is, for example, disk-shaped or ring-shaped, and each member except the insulating member 33 is electrically connected to each other. The lower valve body 32 and the upper valve body 34 are connected to each other at their respective centers, and the insulating member 33 is interposed between their respective peripheral edges. When the internal pressure of the battery increases due to abnormal heat generation, the lower valve body 32 deforms and breaks so as to push the upper valve body 34 toward the cap 35, and the current path between the lower valve body 32 and the upper valve body 34 is interrupted. When the internal pressure further increases, the upper valve body 34 breaks, and gas is discharged from the vent hole 35A of the cap 35.

[0018] The exterior can 20 and the sealing body 30 will be described in further detail with reference to Figure 2. Figure 2 is a cross-sectional view of a cylindrical battery 10. Note that in Figure 2, the electrode body 14 and other components inside the cylindrical battery 10 are not shown.

[0019] As described above, the outer can 20 is a cylindrical metal container that contains the electrode assembly 14 (see FIG. 1) and the electrolyte and has an open upper end. As described above, the outer diameter (φB in the figure) of the open end 20B of the outer can 20 is smaller than the outer diameter (φA in the figure) of the body portion 20A.

[0020] The body portion 20A is a portion of the exterior can 20 that is sandwiched between the bottom and the lower surface of the grooved portion 20C, and is a portion that houses the electrode body 14. The body portion 20A is formed in a cylindrical shape. In this embodiment, the outer diameter of the body portion 20A is preferably 20 mm or more and 35 mm or less. More preferably, it is 20 mm or more and 21 mm or less.

[0021] Open end 20B is a portion sandwiched between the open end of exterior can 20 and the upper surface of grooved portion 20C, and is a portion that accommodates sealing body 30. Open end 20B is formed in a cylindrical shape.

[0022] In this embodiment, the outer diameter of the open end 20B is preferably 2% or more smaller than the outer diameter of the body portion 20A. Furthermore, the outer diameter of the open end 20B is preferably 10% or less smaller than the outer diameter of the body portion 20A. In other words, the outer diameter of the open end 20B is preferably 90% to 98% of the outer diameter of the body portion 20A.

[0023] Furthermore, in this embodiment, the outer diameter of the open end 20B is preferably 5% or more smaller than the outer diameter of the body portion 20A. Furthermore, the outer diameter of the open end 20B is preferably 9% or less smaller than the outer diameter of the body portion 20A. In other words, the outer diameter of the open end 20B is preferably 91% to 95% of the outer diameter of the body portion 20A.

[0024] The sealing body 30 is fixed by crimping to the open end 20B of the outer can 20. A gasket 39 is provided between the outer can 20 and the sealing body 30 to ensure airtightness inside the outer can 20. For the sealing body 30 of this embodiment, a sealing body having a diameter corresponding to the outer diameter of the open end 20B of the outer can 20 is used.

[0025] The manufacturing process of the cylindrical battery 10 will be described with reference to Figures 3 and 4. In the following, Figure 1 may be referred to as appropriate. Figure 3 is a flow diagram showing the flow of the manufacturing process. Figure 4 is a schematic diagram showing a part of the manufacturing process. In Figure 4, the electrode body 14 and the like inside the cylindrical battery 10 are omitted.

[0026] 3, in step S11, the positive electrode 11 and the negative electrode 12 are spirally wound with a separator 13 interposed therebetween to produce an electrode body 14. In step S12, the electrode body 14 is inserted together with an insulating plate 19 into a cylindrical exterior can 20 with a bottom produced by drawing a steel plate. In step S13, the inner surface of the bottom part of the exterior can 20 and the negative electrode lead 16 are welded.

[0027] As shown in FIG. 4(A), in step S14, a diameter reducing die 51 having an inner diameter of φ21 mm to φ18.2 mm and a 10° tapered shape is used to reduce the diameter of the open end 20B (10 mm from the opened upper end side) of the outer can 20 from φ20 mm to φ18.2 mm. By using the diameter reducing die 51 having a tapered shape, the diameter reducing die 51 can be easily separated from the outer can 20 after processing. The diameter reducing process may be performed so that a tapered diameter reducing portion is formed between the body portion 20A and the grooved portion 20C, in which the outer diameter of the outer can 20 decreases toward the grooved portion 20C. By performing step S14 after step S12, the electrode body 14 having an outer diameter larger than the inner diameter of the open end 20B can be inserted into the outer can 20.

[0028] In step S15, insulating plate 18 is inserted into exterior can 20. As shown in Fig. 4(B), in step S16, grooves are machined in opening end 20B that has been machined to reduce its diameter, to form grooved portion 20C. In step S17, a sealant is applied to the inner surface of grooved portion 20C.

[0029] In step S18, a gasket 39 is inserted into the grooved portion 20C. In step S19, the internal terminal plate 31 of the sealing body 30 and the positive electrode lead 15 are welded together. The outer diameters of the sealing body 30 and the gasket 39 are determined according to the outer diameter of the reduced opening end 20B. In step S20, an electrolyte is injected into the outer can 20. In step S21, the sealing body 30 is inserted into the opening end 20B of the outer can 20.

[0030] As shown in Fig. 4(C), in step S22, the sealing body 30 is crimped and fixed using a crimping die (not shown). The crimping die has an upper die that moves up and down, for example, by a press device, and a lower die that receives the upper die in the grooved portion 20C. A split die divided into two is used for the lower die, and when the open end 20B is pressed, one part of the split die is inserted into the grooved portion 20C and receives pressure from the upper die. In step S23, the cylindrical batteries 10 are pressed to adjust the height of the cylindrical batteries 10.

[0031] The effects of the cylindrical battery 10 will be described with reference to Figures 5(A) and 5(B). Figure 5(A) is a cross-sectional view of a cylindrical battery 10 that is an example of an embodiment. Figure 5(B) is a cross-sectional view of a cylindrical battery of a comparative example. Note that in Figures 5(A) and 5(B), the electrode body 14 and other components inside the cylindrical battery 10 are omitted.

[0032] In the cylindrical battery 10 of this embodiment, the outer diameter of the body portion 20A that houses the electrode assembly 14 is larger than that of the cylindrical battery of the comparative example. This allows the exterior can 20 of the cylindrical battery 10 to house an electrode assembly 14 with a larger outer diameter that is filled with a larger amount of active material, thereby achieving a high capacity cylindrical battery 10.

[0033] In conventional cylindrical batteries, the body and the open end have the same outer diameter, as in the comparative example. Therefore, when increasing the capacity by increasing the size of the battery, the outer diameter of the open end is also increased along with the outer diameter of the body. However, if the outer diameter of the sealing body is increased to match the open end, the sealing body will not have enough strength to withstand external impacts or the crimping force required to crimp the sealing body to the outer can, so it is necessary to increase the thickness of the sealing body as well.

[0034] Increasing the thickness of the sealing body requires that the thicknesses of components constituting the sealing body, such as the internal terminal plate, lower valve body, upper valve body or cap, also be increased, resulting in problems such as increased manufacturing costs, increased weight of the sealing body leading to an increase in the weight of the cylindrical battery, and a reduction in battery capacity by the amount of the increased thickness of the sealing body.

[0035] Therefore, by applying the cylindrical battery 10 of this embodiment, it is possible to use a sealing body 30 whose diameter corresponds to the outer diameter of the open end 20B, which is smaller than the outer diameter of the body portion 20A, and this makes it possible to suppress the weight increase and capacity decrease of the cylindrical battery that would otherwise be caused by an increase in the thickness of the sealing body. In this way, a cylindrical battery that can suppress weight increase while increasing capacity can be realized.

[0036] Furthermore, the cylindrical battery 10 of this embodiment has the following advantages. For example, even when the outer diameter of the cylindrical battery's exterior can is changed from φ18.2 mm to φ20 mm, a common sealing body and gasket can be used. A common insulating plate 18 disposed on the upper side of the electrode body 14 may also be used. A common crimping die can also be used in step S22 shown in FIG. 3. This makes it possible to simplify the switching of manufacturing equipment when the outer diameter of the exterior can is changed during the manufacturing process, thereby reducing manufacturing costs.

[0037] It should be noted that the present invention is not limited to the above-described embodiment and its modified examples, and various modifications and improvements are possible within the scope of the matters described in the claims of this application. [Explanation of symbols]

[0038] 10 cylindrical battery, 11 positive electrode, 12 negative electrode, 13 separator, 14 electrode body, 15 positive electrode lead, 16 negative electrode lead, 18 insulating plate, 19 insulating plate, 20 outer can, 20A body portion, 20B opening end, 20C grooved portion, 30 sealing body, 31 internal terminal plate, 32 lower valve body, 33 insulating member, 34 upper valve body, 35 cap, 35A vent hole, 39 gasket, 51 diameter reduction die

Claims

[Claim 1] The battery comprises an electrode assembly in which a positive electrode and a negative electrode are wound with a separator interposed therebetween, an insulating plate disposed on the electrode assembly, an electrolyte, a cylindrical outer can with a bottom that contains the electrode assembly and the electrolyte, and a sealing body that is crimped and fixed to an open end of the outer can, In the outer can, the outer diameter of a body portion that houses the electrode assembly is 20 mm or more and 21 mm or less, The outer diameter of the open end that accommodates the sealing body is 91% to 95% of the outer diameter of the body portion. A method for manufacturing a cylindrical battery, comprising the steps of: an electrode assembly inserting step of inserting the electrode assembly into the outer casing; a diameter reducing step of reducing an outer diameter of the opening end portion after the electrode body inserting step; and an insulating plate inserting step of inserting the insulating plate into the outer can after the diameter reducing step. Manufacturing method for cylindrical batteries.

Images