Cylindrical battery

Abstract

The object of the present disclosure is to provide a cylindrical battery capable of reducing the leakage of electrolyte to the outside of the battery. The cylindrical battery involved in one embodiment of the present disclosure comprises: an electrode body, a positive electrode and a negative electrode are wound with a separator between them; an electrolyte; a bottomed cylindrical outer can (20) for storing the electrode body and the electrolyte; a sealing body (30) for sealing the opening of the outer can (20); and an annular gasket (40) between the outer can (20) and the sealing body (30), the sealing body (30) being fixed to the opening end of the outer can (20) by caulking through the gasket (40), a convex portion (40A) protruding radially outward is formed on the outer peripheral surface of the gasket (40), and the convex portion (40A) abuts against the inner peripheral surface of the opening end of the outer can (20).

Description

Technical Field

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

[0002] In a cylindrical battery, a sealing body that seals the opening of an outer can is fixed to the opening of the outer can via a gasket (for example, Patent Document 1). In the manufacturing process of a cylindrical battery, the electrode body is first inserted into the outer can, and then, after a groove portion supporting the sealing body is formed near the opening of the outer can, an electrolyte is injected into the outer can. The injected electrolyte gradually penetrates into the electrode body, and the liquid level of the electrolyte is lowered from the top of the groove portion to the bottom. At this time, the electrolyte sometimes adheres and remains on the inner circumferential surface of the outer can at a position above the groove portion.

[0003] Prior Art Literature

[0004] Patent Literature

[0005] Patent Document 1: International Publication No. 2016 / 157749 Summary of the invention

[0006] -Problems to be solved by the invention-

[0007] In the manufacturing process of cylindrical batteries, if the sealing body is fixed by caulking with a gasket in a state where the electrolyte is attached to the inner circumferential surface of the outer can at a position above the groove, the attached electrolyte may leak out to the outside of the battery. The leaked electrolyte causes rust on the outer can and the sealing body. In addition, the electrolyte leaks out, which causes the variation of the electrolyte amount in the cylindrical battery.

[0008] An object of the present disclosure is to provide a cylindrical battery capable of reducing leakage of an electrolyte solution to the outside of the battery.

[0009] -Methods for solving the problem-

[0010] A cylindrical battery as one mode of the present invention comprises: an electrode body, in which a positive electrode and a negative electrode are wound with a separator between them; an electrolyte; a bottomed cylindrical outer can that accommodates the electrode body and the electrolyte; a sealing body that seals the opening of the outer can; and an annular gasket that is interposed between the outer can and the sealing body, the sealing body being fixed to the open end of the outer can by caulking with the gasket between them, wherein a convex portion protruding radially outward is formed on the outer peripheral surface of the gasket, and the convex portion abuts against the inner peripheral surface of the open end of the outer can.

[0011] -Effects of the Invention-

[0012] According to one aspect of the present disclosure, leakage of electrolyte to the outside of the battery can be reduced, thereby reducing variations in the amount of electrolyte in the cylindrical battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a cross-sectional view of a cylindrical battery as an example of an embodiment.

[0014] Figure 2 It is a cross-sectional view showing a gasket before a sealing body as an example of an embodiment is inserted into an outer can.

[0015] Figure 3 It is a cross-sectional view showing a gasket before a sealing body as another example of the embodiment is inserted into an outer can.

[0016] Figure 4 It is a cross-sectional view showing a gasket before a sealing body as another example of the embodiment is inserted into an outer can.

[0017] Figure 5A It is a figure for demonstrating the assembly process of a sealing body.

[0018] Figure 5B It is a figure for demonstrating the assembly process of a sealing body.

[0019] Figure 5C It is a figure for demonstrating the assembly process of a sealing body. DETAILED DESCRIPTION

[0020] The following drawings are used to illustrate the embodiments of the present disclosure. The shapes, materials, and numbers described below are examples for illustration and can be appropriately changed according to the specifications of the cylindrical battery. In the following drawings, the same reference numerals are given to the same elements in all the drawings and described.

[0021] use Figure 1 , a cylindrical battery 10 as an example of an embodiment will be described. Figure 1 is a cross-sectional view of the cylindrical battery 10 .

[0022] like Figure 1 As shown, the cylindrical battery 10 includes an electrode body 14, an electrolyte, an outer can 20 for storing the electrode body 14 and the electrolyte, and a sealing body 30 for sealing the opening of the outer can 20. The electrode body 14 includes a positive electrode 11, a negative electrode 12, and a separator 13, and has a structure in which the positive electrode 11 and the negative electrode 12 are wound in a spiral shape with the separator 13 interposed therebetween. In addition, for convenience of description below, the sealing body 30 side (the opening side of the outer can 20) of the cylindrical battery 10 is set as the upper side, and the bottom surface 20A side of the outer can 20 is set as the lower side.

[0023] The positive electrode 11 has a positive electrode core and a positive electrode mixture layer formed on at least one surface of the core. The positive electrode core can use a foil of a metal such as aluminum or aluminum alloy that is stable within the potential range of the positive electrode 11, a film that configures the metal on the surface, etc. The positive electrode mixture layer contains a positive electrode active material, a conductive agent such as acetylene black, and a binder such as polyvinylidene fluoride, and is preferably formed on both sides of the positive electrode core. For example, a lithium transition metal composite oxide is used as the positive electrode active material. The positive electrode 11 can be manufactured by coating a positive electrode mixture slurry containing a positive electrode active material, a conductive agent, a binder, etc. on the positive electrode core, and compressing the coating after drying the coating to form a positive electrode mixture layer on both sides of the core.

[0024] The negative electrode 12 has a negative electrode core and a negative electrode mixture layer formed on at least one surface of the core. The negative electrode core can use a foil of a metal such as copper or copper alloy that is stable within the potential range of the negative electrode 12, a film that configures the metal on the surface, and the like. The negative electrode mixture 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 core. The negative electrode active material is, for example, graphite, a silicon-containing compound, and the like. The negative electrode 12 can be manufactured by coating a negative electrode mixture slurry containing a negative electrode active material, a binder, and the like on the negative electrode core, drying the coating, and then rolling the coating to form a negative electrode mixture layer on both sides of the core.

[0025] The electrolyte solution uses, for example, a non-aqueous electrolyte solution. The non-aqueous electrolyte solution contains a non-aqueous solvent and an electrolyte salt dissolved in the non-aqueous solvent. The non-aqueous solvent can use esters, ethers, nitriles, amides, and mixed solvents of two or more of these solvents. The non-aqueous solvent may also contain a halogen substituent obtained by replacing at least a portion of the hydrogen atoms of these solvents with halogen atoms such as fluorine. The electrolyte salt uses, for example, a lithium salt such as LiPF6. The type of the electrolyte solution is not particularly limited, and it may also be an aqueous electrolyte solution.

[0026] The cylindrical battery 10 has insulating plates 15 and 16 disposed above and below the electrode body 14, respectively. Figure 1 In the example shown, the positive electrode lead 17 connected to the positive electrode 11 extends to the sealing body 30 side through the through hole of the insulating plate 15, and the negative electrode lead 18 connected to the negative electrode 12 extends to the bottom portion 20A side of the outer can 20 through the outside of the insulating plate 16. The positive electrode lead 17 is connected to the bottom surface of the internal terminal plate 31 constituting the sealing body 30 by welding or the like, and the external terminal plate 33 serves as the positive electrode external terminal. The negative electrode lead 18 is connected to the inner surface of the bottom portion 20A of the outer can 20 by welding or the like, and the outer can 20 serves as the negative electrode external terminal.

[0027] The outer can 20 is a metal container with a bottom and a cylindrical shape. A gasket 40 is provided between the outer can 20 and the sealing body 30 to ensure the airtightness of the inside of the cylindrical battery 10. A groove portion 20C for supporting the sealing body 30 is formed in the outer can 20, in which a part of the side portion 20B extends inward. The groove portion 20C is preferably formed in an annular shape along the circumference of the outer can 20, and the sealing body 30 is supported on its upper surface. The sealing body 30 supported by the groove portion 20C is caulked to the open end of the outer can 20, thereby being fixed to the upper part of the outer can 20. At the open end of the outer can 20, a shoulder portion 20D is formed in an annular shape.

[0028] The sealing body 30 is a disc-shaped member having a current interruption mechanism. The sealing body 30 has a structure in which an internal terminal plate 31, an insulating plate 32, and an external terminal plate 33 are stacked in order from the electrode body 14 side. The internal terminal plate 31 is a metal plate including an annular portion 31A connected to the positive lead 17 and a thin-walled central portion 31B that is cut off from the annular portion 31A when the internal pressure of the battery exceeds a given threshold. A vent hole 31C is formed in the annular portion 31A.

[0029] The external terminal plate 33 is arranged opposite to the internal terminal plate 31 with the insulating plate 32 sandwiched therebetween. The insulating plate 32 is provided with an opening 32A in the radial center, and a vent hole 32B is formed in the portion of the internal terminal plate 31 overlapping with the vent hole 31C. The external terminal plate 33 has a valve portion 33A that breaks when the internal pressure of the cylindrical battery 10 exceeds a given threshold, and the valve portion 33A is connected to the central portion 31B of the internal terminal plate 31 via the opening 32A of the insulating plate 32 by welding or the like. The insulating plate 32 insulates the internal terminal plate 31 and the external terminal plate 33 around their connection portion.

[0030] The valve portion 33A includes a lower convex portion protruding toward the inside of the battery and a thin-walled portion formed around the lower convex portion, and is formed in the radial center of the external terminal plate 33. In the cylindrical battery 10, the internal terminal plate 31 connected to the positive lead 17 is electrically connected to the external terminal plate 33, thereby forming a current path connected from the electrode body 14 to the external terminal plate 33. If an abnormality occurs in the cylindrical battery 10 and the internal pressure rises, the internal terminal plate 31 breaks, the central portion 31B is cut off from the annular portion 31A, and the valve portion 33A is deformed to become convex toward the outside of the battery. As a result, the current path is cut off. If the internal pressure of the cylindrical battery 10 rises further, the valve portion 33A breaks to form a gas discharge port.

[0031] In addition, the structure of the sealing body is not limited to Figure 1 The sealing body may also have a convex sealing body cover covering the valve body. In addition, the negative electrode lead may be connected to the inner surface of the sealing body, and the positive electrode lead may be connected to the inner surface of the outer can. In this case, the sealing body becomes the negative electrode external terminal, and the outer can becomes the positive electrode external terminal.

[0032] use Figure 2 The gasket 40 will be described. Figure 2 It is a cross-sectional view showing the gasket 40 before the sealing body 30 is inserted into the opening of the outer can 20 .

[0033] The gasket 40 is a sealing material interposed between the outer can 20 and the sealing body 30. The gasket 40 can seal the gap between the sealing body 30 and the opening of the outer can 20, thereby ensuring the airtightness of the interior of the outer can 20. The gasket 40 of this embodiment uses a polyolefin resin, but is not limited to this.

[0034] The gasket 40 is formed in a substantially annular shape. Before the sealing body 30 is crimped to the outer can 20, the gasket 40 is formed in a substantially L-shaped shape in a circumferential cross-sectional view, and after the sealing body 30 is crimped to the outer can 20, the gasket 40 is deformed into a substantially C-shaped shape in a circumferential cross-sectional view (see FIG. Figure 1 ) The gasket 40 has a convex portion 40A protruding outward in the radial direction on the outer peripheral surface.

[0035] The upper portion of the gasket 40 extends in the vertical direction before the sealing body 30 is crimped to the outer can 20 , and is bent when the sealing body 30 is crimped to the outer can 20 , thereby being sandwiched and compressed by the shoulder 20D of the outer can 20 and the external terminal plate 33 .

[0036] The lower portion of the gasket 40 is disposed between the groove 20C of the outer can 20 and the external terminal plate 33 before the sealing body 30 is crimped to the outer can 20 , and is sandwiched and compressed by the groove 20C of the outer can 20 and the external terminal plate 33 when the sealing body 30 is crimped to the outer can 20 .

[0037] As described above, the convex portion 40A protrudes radially outward on the outer peripheral surface of the gasket 40. The convex portion 40A is formed over the entire circumference of the gasket 40. The convex portion 40A abuts between the groove portion 20C and the shoulder portion 20D on the inner peripheral surface of the side portion 20B of the outer can 20. According to the convex portion 40A, the details will be described later, but when the sealing body 30 is inserted into the opening of the outer can 20, the electrolyte attached to the inner peripheral surface of the outer can 20 can be scraped off. In addition, the convex portion 40A is a portion that is not compressed when the sealing body 30 is crimped to the outer can 20.

[0038] The outer diameter of the front end portion of the convex portion 40A of the gasket 40 (hereinafter referred to as the maximum diameter of the gasket) is preferably set to the length of the front end portion of the convex portion 40A abutting against the inner peripheral surface of the side portion 20B of the outer can 20. The maximum diameter of the convex portion 40A is preferably greater than the inner diameter of the outer can 20. The radial length of the convex portion 40A (the length from the outer peripheral surface of the gasket 40 to the front end of the convex portion 40A (dimension A in the figure)) is preferably, for example, 0.05 mm to 0.15 mm.

[0039] Thus, when the sealing body 30 is inserted into the opening of the outer can 20, the entire circumference of the convex portion 40A abuts against the inner circumferential surface of the outer can 20 without a gap, and the sealing body 30 is inserted into the opening of the outer can 20. In addition, when the sealing body 30 and the gasket 40 are inserted into the opening of the outer can 20, the center position of the gasket 40 in a plan view can be easily aligned with the center position of the opening of the outer can 20. Thus, the workability in the manufacturing process of the cylindrical battery 10 can be improved.

[0040] The outer diameter of a portion of the outer peripheral surface of the gasket 40 where the convex portion 40A is not formed (hereinafter referred to as a gasket diameter) is preferably smaller than the inner diameter of the outer can 20 .

[0041] The convex portion 40A is formed so that the vertical position of the front end portion is located at a position lower than the position of the upper surface of the external terminal plate 33. Specifically, it is preferred that the difference between the vertical position of the front end portion of the convex portion 40A and the vertical position of the upper surface of the external terminal plate 33 (dimension B in the figure) is 1.0 mm to 1.5 mm. As a result, it is possible to avoid the convex portion 40A being compressed by the shoulder 20D of the outer can 20 being pressed against the upper surface of the external terminal plate 33 during caulking. Furthermore, it is possible to avoid a reduction in the sealing performance of the sealing body 30.

[0042] The cross-sectional shape of the convex portion 40A in the circumferential direction is not particularly limited, and may be the same width from the root to the tip, but is preferably a tapered shape. Figure 2 In the example shown, the cross-sectional shape of the convex portion 40A in the circumferential direction is a trapezoidal shape. Thus, when the sealing body 30 and the gasket 40 are inserted into the opening of the outer can 20, the frictional resistance is reduced, and the sealing body 30 and the gasket 40 can be easily inserted.

[0043] like Figure 3 As shown in FIG. 1 , the cross-sectional shape of the convex portion 40A in the circumferential direction may also be a triangle. Figure 4 As shown, the cross-sectional shape of the convex portion 40A in the circumferential direction may be a triangle shape whose oblique sides reach the lower end of the gasket 40 .

[0044] use Figure 5A , Figure 5B and Figure 5C , the manufacturing process of the cylindrical battery 10 as an example of this embodiment is described. Figure 5A , Figure 5B and Figure 5C It is a diagram for explaining the assembly process of the sealing body 30 .

[0045] In the manufacturing process of the cylindrical battery 10, first, the electrode body 14 is inserted into the outer can 20. The sealing body 30 is connected to the electrode body 14 via the positive electrode lead 17. Next, near the opening of the outer can 20, a groove portion 20C for supporting the sealing body 30 is formed by spinning from the outside of the side surface portion 20B of the outer can 20.

[0046] Next, the electrolyte is poured into the outer can 20 until the liquid level is above the groove 20C. The electrolyte gradually penetrates into the electrode body 14, and the electrolyte level drops from above the groove 20C to below. At this time, the electrolyte may adhere to and remain above the groove 20C on the inner circumferential surface of the outer can 20.

[0047] Next, if Figure 5A As shown, the sealing body 30 is inserted into the opening of the outer can 20. When the gasket maximum diameter of the gasket 40 is equal to or larger than the inner diameter of the outer can 20, the convex portion 40A can contact the inner circumferential surface of the outer can 20 without any gap over the entire circumference.

[0048] Next, if Figure 5B As shown in the figure, the sealing body 30 is inserted into the opening of the outer can 20. At this time, the electrolyte adhering to the inner peripheral surface of the outer can 20 is scraped off by the convex portion 40A. Even if the maximum diameter of the gasket is smaller than the inner diameter of the outer can 20, the convex portion 40A is formed to exert the scraping effect of the electrolyte, but as in the present embodiment, the maximum diameter of the gasket is preferably greater than the inner diameter of the outer can 20. The electrolyte scraped off by the convex portion 40A moves along the inner peripheral surface of the outer can 20 and passes over the concave portion 20C, and falls toward the injected electrolyte.

[0049] Next, if Figure 5C As shown, the open end of the outer can 20 is caulked, and the sealing body 30 is fixed to the open end of the outer can 20. At this time, a shoulder 20D is formed at the open end of the outer can 20 in an annular shape.

[0050] The following describes the effects of the cylindrical battery 10. According to the cylindrical battery 10, leakage of the electrolyte to the outside of the cylindrical battery 10 can be reduced.

[0051] According to the cylindrical battery 10, when the sealing body 30 is inserted into the outer can 20, the electrolyte adhering to the inner peripheral surface of the outer can 20 is scraped off by the convex portion 40A formed on the gasket 40. As a result, when the sealing body 30 is crimped to the outer can 20, no electrolyte remains between the gasket 40 and the inner peripheral surface of the outer can 20. Therefore, the leakage of the electrolyte to the outside of the cylindrical battery 10 can be reduced.

[0052] When the sealing body 30 is inserted into the outer can 20, the electrolyte adhering to the inner peripheral surface of the outer can 20 is scraped off by the convex portion 40A, thereby reducing the variation in the amount of electrolyte in the cylindrical battery 10. Thus, the tolerance of the amount of electrolyte in the cylindrical battery 10 can be reduced.

[0053] In addition, the present invention is not limited to the above-described embodiment and its modified examples, and various changes and improvements can be implemented within the scope of the matters described in the claims of the present application.

[0054] -Explanation of symbols-

[0055] 10 cylindrical battery, 11 positive electrode, 12 negative electrode, 13 separator, 14 electrode body, 15 insulating plate, 16 insulating plate, 17 positive electrode lead, 18 negative electrode lead, 20 outer can, 20A bottom portion, 20C groove portion, 20D shoulder portion, 30 sealing body, 31 internal terminal plate, 31A annular portion, 31B central portion, 31C vent hole, 32 insulating plate, 32A opening portion, 32B vent hole, 33 external terminal plate, 33A valve portion, 40 gasket, 40A convex portion.

Claims

1. A cylindrical battery comprising: An electrode body, in which the positive electrode and the negative electrode are wound with a separator between them; Electrolyte; An outer container having a bottom and in a cylindrical shape, containing the electrode body and the electrolyte; a sealing body for sealing the opening of the outer can; and An annular gasket is interposed between the outer can and the sealing body. The sealing body is fixed to the opening end of the outer can by caulking through a gasket. in, A convex portion protruding radially outward is formed on the outer peripheral surface of the gasket, The convex portion abuts against the inner peripheral surface of the opening end of the outer can. The maximum diameter of the protrusion is larger than the inner diameter of the outer can. The convex portion is a portion that is not compressed when the sealing body is caulked to the outer can.

2. The cylindrical battery according to claim 1, wherein: The convex portion is formed below the upper surface of the sealing body.

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