Cylindrical battery

Abstract

A cylindrical battery (10) comprises: a housing canister (16) which is bottomed and which accommodates an electrode body (14); and an opening-sealing body (17) which is fixed to a crimping section (31) by crimping with a gasket (18) interposed therebetween, the crimping section being formed by bending an opening part of the housing canister (16). The opening-sealing body (17) includes a cap (28) that includes a flange part (28b) which is crimped by the crimping section (31). The flange part (28b) of the cap (28) includes a recess (28c) the thickness of which is made thin. The gasket (18) includes a projection (18a) that projects from the leading edge of the crimping section (31) and that fits into the recess (28c).

Description

[[Technical Field]]

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

[0002] Applications of lithium ion batteries are expanding to vehicle mounting, power sources and power storage. Mounting on products is achieved by connecting a large number of cells in series and / or in parallel to form a module. For electrical connection of cells, there are an increasing number of customer requests for single-sided connection, in which the positive side is connected via the cell positive electrode on the top surface of the cap, and the negative side is connected via the crimped portion (crimped shoulder) of the cell.

[0003] Patent Document 1 describes a sealed cylindrical battery obtained by crimping a sealing body to an opening of an outer can via a gasket. [[Prior Art Literature]] [[Patent Literature]]

[0004] [[Patent Document 1]] Japanese Patent Laid-Open No. 2008-282679 [[Summary of Invention]]

[0005] When a connecting plate is welded at the crimped shoulder by single-sided connection of the cylindrical battery described in Patent Document 1 and the like, welding defects occur if there is a gap between the crimped shoulder and the connecting plate. The cause of this gap is that the gasket bulges upward beyond the crimped shoulder, and the gasket interferes with the connecting plate. As a countermeasure against this, it is conceivable to shorten the gasket protruding from the tip of the crimped portion. However, if the gasket protruding from the tip of the crimped portion is shortened, there is a risk that the insulation performance between the tip of the crimped portion and the cap may decrease.

[0006] An object of the present disclosure is to provide a cylindrical battery that can prevent the formation of a gap between the crimped shoulder and the connecting plate when welding the connecting plate at the crimped shoulder, and can ensure welding quality.

[0007] The cylindrical battery according to this disclosure comprises a bottomed cylindrical outer casing that houses an electrode body, and a sealing body that is crimped and fixed via a gasket to a crimped portion formed by bending the opening of the outer casing. The sealing body has a cap with a flange portion that is crimped to the crimped portion, the flange portion of the cap has a recess formed with a thin plate thickness, and the gasket is characterized in that a protruding portion that extends from the tip of the crimped portion fits into the recess.

[0008] In the cylindrical battery according to this disclosure, the gasket protruding from the tip of the crimped portion is not located above the crimped shoulder portion. Therefore, when welding the connecting plate at the crimped shoulder portion, no gap is created between the crimped shoulder portion and the connecting plate, and welding quality can be ensured. [Brief explanation of the drawing]

[0009] [Figure 1] These are a side view and a partial cross-sectional view of the cylindrical battery according to the embodiment. [Figure 2] This is a plan view of the sealing body of the embodiment. [Figure 3] This is an enlarged cross-sectional view of the vicinity of the crimped portion when the connecting plate is welded at the crimped shoulder portion in the cylindrical battery of the first embodiment. [Figure 4] This is an enlarged cross-sectional view of the vicinity of the crimped portion when the connecting plate is welded at the crimped shoulder portion in the cylindrical battery of the second embodiment. [Figure 5] This is an enlarged cross-sectional view of the vicinity of the crimped portion when the connecting plate is welded at the crimped shoulder of a conventional cylindrical battery. [Modes for carrying out the invention]

[0010] The embodiments of this disclosure will be described in detail below with reference to the drawings. In the following description, specific shapes, materials, directions, numerical values, etc., are examples to facilitate understanding of this disclosure and can be appropriately modified according to the application, purpose, specifications, etc. Furthermore, it is intended from the outset that the components of the embodiments and modifications described below can be selectively combined.

[0011] Hereinafter, an example of an embodiment of the cylindrical battery 10 according to this disclosure will be described in detail with reference to the drawings. Figure 1 is a side view and a partial cross-sectional view of the cylindrical battery 10, which is an example of an embodiment.

[0012] <First Embodiment> As shown in Figure 1, the cylindrical battery 10 comprises a bottomed cylindrical outer casing 16 including a bottom portion 16a and side portions 16b, a sealing body 17 that closes the opening of the outer casing 16, and a gasket 18 interposed between the outer casing 16 and the sealing body 17. The cylindrical battery 10 also comprises an electrode body 14 and an electrolyte housed in the outer casing 16. 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 via the separator 13.

[0013] In this specification, for the sake of explanation, the direction along the axial direction of the outer casing 16 is referred to as the "vertical direction or up-and-down direction," with the sealing body 17 side of the cylindrical battery 10 (the opening side of the outer casing 16) being considered the top and the bottom surface 16a side of the outer casing 16 being considered the bottom.

[0014] The positive electrode 11 comprises a positive electrode core and a positive electrode mixture layer formed on at least one surface of the core. The positive electrode core can be made of a metal foil that is stable within the potential range of the positive electrode 11, such as aluminum or an aluminum alloy, or a film with the metal arranged on its surface. 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 can be used as the positive electrode active material.

[0015] The negative electrode 12 comprises a negative electrode core and a negative electrode mixture layer formed on at least one surface of the core. The negative electrode core can be made of a metal foil that is stable within the potential range of the negative electrode 12, such as copper or a copper alloy, or a film with the metal arranged on its surface. 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. Examples of negative electrode active materials include graphite and silicon-containing compounds.

[0016] The electrolyte may be an aqueous electrolyte or a non-aqueous electrolyte. Furthermore, it may be either a liquid or solid electrolyte. In this embodiment, a non-aqueous electrolyte is used. The non-aqueous electrolyte comprises 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 mixtures of two or more of these. The non-aqueous solvent may contain halogen-substituted solvents in which at least some of the hydrogen atoms in the solvent are replaced with halogen atoms such as fluorine. Examples of electrolyte salts used include lithium salts such as LiPF6.

[0017] The cylindrical battery 10 includes insulating plates 19 and 20 positioned above and below the electrode body 14, respectively. In the example shown in Figure 1, a positive electrode tab 21 connected to the positive electrode 11 extends through a through hole in the insulating plate 19 towards the sealing body 17. Negative electrode tabs 22 are connected to the outermost and innermost circumferences of the negative electrode 12, respectively. The negative electrode tab 22 connected to the outermost circumference of the negative electrode 12 extends outside the insulating plate 20 towards the bottom surface 16a of the outer casing 16, while the negative electrode tab 22 connected to the innermost circumference of the negative electrode 12 extends through a through hole in the insulating plate 20 to the bottom surface 16a of the outer casing 16. The positive electrode tab 21 is connected to the terminal plate 25, which is the bottom plate of the sealing body 17, by welding or the like, and the cap 28 of the sealing body 17, which is electrically connected to the terminal plate 25, becomes the positive electrode external terminal. The negative electrode tab 22 is connected to the inner surface of the bottom surface 16a of the outer casing 16 by welding or the like, and the outer casing 16 becomes the negative electrode external terminal. The detailed structure of the sealing body 17 will be described later.

[0018] The outer casing 16 is a metal container with an axial end (upper end) open, a bottom surface 16a that is disc-shaped, and a side surface 16b that is cylindrical along the outer edge of the bottom surface 16a. The sealing body 17 is formed in a disc shape corresponding to the shape of the opening of the outer casing 16. The gasket 18 is an annular member made of resin that ensures airtightness inside the battery and ensures electrical insulation between the outer casing 16 and the sealing body 17.

[0019] In the outer can 16, an opening edge (upper end) is bent inward, and a crimped portion 31 that presses the sealing body 17 via the gasket 18 is formed. In addition, in the outer can 16, a grooved portion 30 that is formed by protruding the side surface portion 16b from the outside to the inside and supports the sealing body 17 via the gasket 18 is formed. The grooved portion 30 is annularly formed along the circumferential direction of the outer can 16 by spinning from the outside of the side surface portion 16b.

[0020] The crimped portion 31 faces the grooved portion 30 via the sealing body 17 and the gasket 18, and clamps the sealing body 17 together with the grooved portion 30. Similar to the grooved portion 30, the crimped portion 31 is annularly formed along the circumferential direction of the outer can 16, and presses the peripheral edge of the sealing body 17 from above via the gasket 18. The crimped portion 31 has a crimped shoulder 31a which is the highest portion in the axial direction of the outer can 16.

[0021] The sealing body 17 is a disk-shaped member provided with a CID mechanism (current interrupt mechanism). The sealing body 17 has a structure in which a terminal plate 25, an insulating plate 27, a rupture disk 26 and a cap 28 are laminated in this order from the electrode body 14 side. The terminal plate 25 is a metal plate including an annular portion to which the positive electrode tab 21 is connected, and a thin-walled central portion that is disconnected from the annular portion when the internal pressure of the battery exceeds a predetermined threshold.

[0022] The rupture disk 26 is disposed opposite to the terminal plate 25 with the insulating plate 27 interposed therebetween. The rupture disk 26 has a valve body 26a that breaks when the internal pressure of the battery exceeds a predetermined threshold, and an outer peripheral portion crimped to the crimped portion 31 on the outer peripheral side. The valve body 26a is connected to the central portion of the terminal plate 25 by welding or the like. When an abnormality occurs in the battery, the internal pressure rises and exceeds the operating pressure of the CID mechanism, the terminal plate 25 breaks, the central portion is disconnected from the annular portion, and the valve body 26a deforms so as to be convex toward the outside of the battery. This interrupts the current path. When the internal pressure of the battery further rises and exceeds the vent pressure, the valve body 26a breaks to form a gas discharge port.

[0023] Here, the cause of welding defects occurring at the crimped shoulder 131a in the conventional cylindrical battery 100 will be described. FIG. 5 is an enlarged cross-sectional view of the vicinity of the crimped portion 131 when the connecting plate 140 is welded at the crimped shoulder 131a in the cylindrical battery 100.

[0024] In the conventional cylindrical battery 100 shown in FIG. 5, the structure other than the flange portion 128b of the cap 128 is the same as that of the cylindrical battery 10 of the present embodiment shown in FIG. 1. The flange portion 128b of the cap 128 of the cylindrical battery 100 is formed into an annular shape with a flat and uniform plate thickness.

[0025] In the conventional cylindrical battery 100, it is the same that the crimped portion 131 is formed by crimping the flange portion 128b of the cap 128 and the rupture disk 126 at the opening edge of the outer can 116 via the gasket 118. In the conventional cylindrical battery 100, at the distal end portion 131b on the radially inner peripheral side of the crimped portion 131, the gasket 118 is pressed against the flange portion 128b from above and is deformed the most. For this reason, the protruding portion 118a of the gasket 118 rebounds from the flange portion 128b starting from the distal end portion 131b of the crimped portion 131 and bulges upward. Therefore, if the radial length of the protruding portion 118a of the gasket 118 is long, the distal end of the protruding portion 118a of the gasket 118 will be positioned upward beyond the crimped shoulder 131a.

[0026] In the cylindrical battery 100 in this state, when welding the connecting plate 140 at the crimped shoulder 131a, the distal end of the protruding portion 118a of the gasket 118 interferes with the connecting plate 140, and as shown in FIG. 5, a gap d is generated between the connecting plate 140 and the crimped shoulder 131a. Therefore, due to the presence of the gap d, welding defects between the connecting plate 140 and the crimped shoulder 131a may occur.

[0027] Next, with reference to FIG. 1, the reason why welding defects of the connecting plate 40 are suppressed in the structure of the sealing body 17 of the cylindrical battery 10 according to the first embodiment will be described.

[0028] The cylindrical battery 10 of this embodiment comprises a bottomed cylindrical outer casing 16 that houses the electrode body 14, and a sealing body 17 that is crimped and fixed via a gasket 18 to a crimped portion 31 formed by bending the opening of the outer casing 16. The sealing body 17 has a cap 28 with a convex portion 28a that protrudes upward in the center and a flange portion 28b on the outer circumference of the convex portion 28a. The flange portion 28b of the cap 28 has a recess 28c formed with a thin plate thickness, and the gasket 18 is configured such that a convex portion 18a that protrudes from the radial end of the crimped portion 31 fits into the recess 28c.

[0029] In this embodiment, the cylindrical battery 10 has a thin plate thickness in the recess 28c of the flange portion 28b. By pressing the gasket 18 with the tip 31b of the crimping portion 31, the tip of the protruding portion 18a of the gasket 18 deforms to fit into the recess 28c. Therefore, the tip of the gasket 18 is never positioned above the crimping shoulder portion 31a. When connecting the cylindrical battery 10 to the external terminal, the connecting plate 40 can be made to contact the crimping shoulder portion 31a without any gaps, enabling reliable welding. The configuration of the sealing body 17 in this embodiment makes it possible to ensure the quality of the welding of the external terminal.

[0030] Referring to Figures 2 and 3, the structure of the sealing body 17 and crimped portion 31 of the cylindrical battery 10 of this embodiment will be further described. Figure 2 is a view of the cylindrical battery 10 of this embodiment from above. Figure 3 is an enlarged cross-sectional view of the vicinity of the crimped portion 31 when the connecting plate 40 is welded with the crimped shoulder portion 31a.

[0031] The crimping portion 31 is formed in an annular shape, extending radially inward from the opening edge of the outer can 16. The crimping portion 31 crimps and presses the flange portion 28b and the rupture disc 26 via the gasket 18. The flange portion 28b has an annular recess 28c formed on the inner circumference side from the inner circumference tip 31b of the crimping portion 31. The gasket 18 has a projection 18a that protrudes radially inward from the inner circumference tip 31b of the crimping portion 31. The projection 18a of the gasket 18 fits into the recess 28c of the flange portion 28b. Further on the inner circumference side of the flange portion 28b, a convex portion 28a is formed. Multiple holes 28d are formed in the convex portion 28a, but this is not an essential configuration.

[0032] As shown in Figure 3, when the radial length of the protrusion 18a of the gasket 18 is r and the radial length of the recess 28c is R, the recess 28c is formed such that R > r. By forming it in this way, the tip of the protrusion 18a of the gasket 18 is securely fitted into the recess 28c. Therefore, the protrusion 18a of the gasket 18 does not rise above the crimping shoulder 31a, and when the connecting plate 40 is welded at the crimping shoulder 31a, no gap is created between the crimping shoulder 31a and the connecting plate 40. Thus, the cylindrical battery 10 of this embodiment has a structure that suppresses welding defects of the connecting plate 40 at the crimping shoulder 31a.

[0033] It is preferable that the position of the inner circumferential tip 31b of the crimping portion 31 and the position of the outer circumferential edge of the recess 28c be formed to be approximately the same. If the position of the outer circumferential edge of the recess 28c is on the inner circumferential side than the tip 31b of the crimping portion 31, the tip 31b will press the gasket 18 against the flat portion of the flange portion 28b, and as in the conventional structure, the protruding portion 18a of the gasket 18 may rebound upward from the flange portion 28b, starting from the tip 31b, and rise upward.

[0034] <Second Embodiment> Figure 4 is an enlarged cross-sectional view of the vicinity of the crimped portion 31 when the connecting plate 40 is welded to the crimped shoulder portion 31a of the cylindrical battery 10 of the second embodiment. The view of the cylindrical battery 10 of the second embodiment from above is the same as that of the first embodiment, so it is omitted from the illustration. The cylindrical battery 10 of the second embodiment differs from the cylindrical battery 10 of the first embodiment in the cross-sectional shape of the recess 28c provided in the flange portion 28b.

[0035] In this embodiment as well, when the radial length of the protrusion 18a of the gasket 18 is r and the radial length of the recess 28c is R, the recess 28c is formed such that R > r. By forming it in this way, the tip of the protrusion 18a of the gasket 18 is reliably fitted into the recess 28c.

[0036] Furthermore, the recess 28c in the second embodiment is formed to have a slope in which the plate thickness decreases from the outer edge of the recess 28c toward the radially inner side. The position of the outer edge of the recess 28c is formed to be substantially the same as the position of the inner tip 31b of the crimping portion 31. Therefore, the gasket 18 of the cylindrical battery 10 in this embodiment slopes gently downward from the tip 31b of the crimping portion 31 along the slope of the recess 28c.

[0037] In the second embodiment, the recess 28c is provided with an inclination to suppress upward movement of the gasket 18, and the plate thickness on the outer circumference of the flange portion 28b is secured to suppress a decrease in strength.

[0038] Furthermore, in the second embodiment, the recess 28c is formed in a slope such that the plate thickness gradually decreases from the vicinity of the tip 31b of the crimping portion 31. Therefore, even when the position of the tip 31b of the crimping portion 31 extends radially inward, the airtightness of the sealing body 17 can be improved.

[0039] As described above, the cylindrical battery 10 of this disclosure has a recess 28c in the flange portion 28b of the cap 28, which prevents the protruding portion 18a of the gasket 18 from rising above the crimped shoulder portion 31a after the outer casing 16 is crimped. Therefore, there is no need to shorten the protruding portion 18a of the gasket 18 from the crimped portion 31, so there is no risk of a decrease in the insulation performance between the tip portion 31b of the crimped portion 31 and the cap 28, and the welding quality when welding the connecting plate 40 at the crimped shoulder portion 31a can be ensured.

[0040] Next, the results of verifying the suppression of upward protrusion of the gasket 18 from the crimped portion 31 in the cylindrical battery 10 of this disclosure will be described using examples. A cylindrical battery 10 was manufactured under the following conditions, and it was verified whether or not the gasket 18 protruded above the crimped shoulder portion 31a. 100 cylindrical batteries 10 of Examples 1 to 4 and 100 cylindrical batteries 100 of the comparative example were manufactured.

[0041] <Example 1> In the cylindrical battery 10 of the first embodiment shown in Figure 3, a cylindrical battery 10 was manufactured having a recess 28c with a radial length R = 1.3 mm and a depth h = 0.10 mm. The thickness of the flange portion 28b was set to 0.4 mm.

[0042] <Example 2> In the cylindrical battery 10 of the first embodiment shown in Figure 3, a cylindrical battery 10 was fabricated having a recess 28c with a radial length R = 1.3 mm and a depth h = 0.15 mm. The rest is the same as in Example 1.

[0043] <Example 3> In the cylindrical battery 10 of the second embodiment shown in Figure 4, a cylindrical battery 10 was fabricated having a recess 28c with an inclination angle θ = 10°, a radial length R = 1.3 mm, and a depth h = 0.23 mm. The rest is the same as in Example 1.

[0044] <Example 4> In the cylindrical battery 10 of the second embodiment shown in Figure 4, a cylindrical battery 10 was fabricated having a recess 28c with an inclination angle θ = 12°, a radial length R = 1.3 mm, and a depth h = 0.28 mm. The rest is the same as in Example 1.

[0045] <Comparative Example> As a comparative example, a conventional cylindrical battery 100, as shown in Figure 5, was fabricated. The thickness of the flange portion 128b was set to 0.4 mm.

[0046] Table 1 shows the verification results regarding whether the protruding portions 18a and 118a of the gaskets 18 and 118 of the cylindrical batteries 10 and 100 of Examples 1 to 4 protrude above the crimped shoulder portions 31a and 131a. [Table 1]

[0047] <Rating> In the cylindrical batteries 10 of Examples 1 and 2, regardless of the depth h of the recess 28c of the flange portion 28b, no instances were observed where the protruding portion 18a of the gasket 18 protruded above the crimped shoulder portion 31a. In the cylindrical batteries 10 of Examples 3 and 4, regardless of the inclination angle θ of the recess 28c of the flange portion 28b being 10° or 12°, no instances were observed where the protruding portion 18a of the gasket 18 protruded above the crimped shoulder portion 31a. In contrast, in the comparative example cylindrical battery 100, in 4 out of 100 units, it was observed that the protruding portion 118a of the gasket 118 protruded above the crimped shoulder portion 131a.

[0048] From the results above, it can be seen that in the cylindrical battery 10 of this disclosure, the protruding portion 18a of the gasket 18 does not protrude above the crimped shoulder portion 31a, and therefore, the welding performance of the connecting plate at the crimped shoulder portion is superior to that of the conventional cylindrical battery 100.

[0049] It should be noted that the present invention is not limited to the embodiments and their modifications described above, and various changes and improvements are possible within the scope of the claims of this application. [Explanation of symbols]

[0050] 10, 100 Cylindrical battery, 11 Positive electrode, 12 Negative electrode, 13 Separator, 14 Electrode body, 16 Outer casing, 16a Bottom, 16b Side, 17 Sealing body, 18, 118 Gasket, 18a, 118a Protruding part, 19 Insulating plate, 20 Insulating plate, 21 Positive electrode tab, 22 Negative electrode tab, 25 Terminal plate, 26, 126 Rupture disk, 27 Insulating plate, 28, 128 Cap, 28a Protruding part, 28b, 128b Flange part, 28c Recessed part, 28d Hole, 30 Grooved part, 31, 131 Crimping part, 31a, 131a Crimping shoulder part, 31b, 131b Tip part, 40, 140 Connecting plate

Claims

1. A bottomed cylindrical outer container that houses the electrode body, A sealing body is crimped and fixed to the crimped portion formed by bending the opening of the outer can via a gasket, Equipped with, The sealing body has a cap with a flange portion that is crimped to the crimping portion, The flange portion of the cap has a recess formed with a thin plate thickness, The gasket has a protruding portion that extends from the radial tip of the crimped portion and fits into the recess. Cylindrical battery.

2. The recess has a slope in which the plate thickness decreases toward the radially inner circumference of the flange portion. The cylindrical battery according to claim 1.

3. When the radial length of the protruding portion of the gasket is r and the radial length of the recess is R, the gasket is formed such that R > r. A cylindrical battery according to claim 1 or 2.

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