Cylindrical battery

Abstract

The purpose of the present disclosure is to provide a cylindrical battery for which it is possible to extend a crimped part to a greater length while suppressing deformation of a sealing body. The cylindrical battery according to an exemplary embodiment comprises a bottomed cylindrical outer can, a sealing body that closes an opening in the outer can, and a gasket interposed between the outer can and the sealing body. On the outer can, an edge of the opening is curved inward, and a crimped part is formed pressing the sealing body via the gasket. The crimped part includes: a base-end-side part that is inclined so that the gap with the sealing body becomes smaller toward the inside of the outer can; and a tip-end-side part that is inclined at a smaller angle at the sealing-body side than the base-end-side part, or is parallel to the bottom surface part of the outer can, or is inclined so that the gap with the sealing body becomes larger toward the tip end.

Description

[Technical Field]

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

[0002] Conventionally, cylindrical batteries have been widely known that include a cylindrical outer can with a bottom, a sealing body that closes the opening of the outer can, and a gasket that is interposed between the outer can and the sealing body (see, for example, Patent Documents 1 and 2). The outer can generally has a crimped portion formed by bending the edge of the opening inward and pressing the sealing body via the gasket. In a cylindrical battery, for example, a positive electrode lead is connected to the inner surface of the sealing body, making the sealing body the positive electrode external terminal, and a negative electrode lead is connected to the inner surface of the outer can, making the outer can the negative electrode external terminal. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-152031 [Patent Document 2] Special Publication No. 2010-512638 Summary of the Invention [Problem to be solved by the invention]

[0004] In some cases, multiple cylindrical batteries are electrically connected to form a module, and external leads are connected to the positive and negative external terminals. In this case, to reduce the size of the battery module, the external lead may be connected to a crimped portion of the outer can serving as the negative external terminal, which is located close to the sealing body. In this case, extending the crimped portion is considered to increase the connection area of ​​the external lead and improve the workability of lead connection. However, simply extending the crimped portion makes the sealing body more susceptible to deformation due to the large pressure applied by the crimped portion. Deformation of the sealing body can lead to problems such as increased variability in the operating pressure of the safety valve provided in the sealing body and unstable connection positions when connecting the external lead to the sealing body. [Means for solving the problem]

[0005] A cylindrical battery according to one aspect of the present disclosure comprises a cylindrical outer can with a bottom, a sealing body that closes the opening of the outer can, and a gasket that is interposed between the outer can and the sealing body, wherein the outer can has a crimped portion formed by bending the edge of the opening inward and pressing the sealing body via the gasket, and the crimped portion includes a base end portion that is inclined so that the distance between the crimped portion and the sealing body decreases toward the inside of the outer can, and a tip end portion that is inclined at a smaller angle toward the sealing body than the base end portion, or is parallel to the bottom surface of the outer can, or is inclined so that the distance between the crimped portion and the sealing body increases toward the tip. [Effects of the Invention]

[0006] According to a cylindrical battery according to one aspect of the present disclosure, the crimped portion can be elongated while suppressing deformation of the sealing body, thereby ensuring a sufficient connection area for the external lead at the crimped portion without causing a performance degradation due to deformation of the sealing body, and improving the workability of lead connection when modularizing cylindrical batteries. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a longitudinal cross-sectional view of a cylindrical battery according to an embodiment of the present invention. [Figure 2] FIG. 2 is an enlarged view of a part of the grooved portion, the crimped portion, and the sealing body of the outer can in FIG. [Figure 3] FIG. 3 is a diagram for explaining the configuration of the caulking portion. DETAILED DESCRIPTION OF THE INVENTION

[0008] An example of an embodiment of a cylindrical battery according to the present disclosure will be described in detail below with reference to the drawings. Figure 1 is a cross-sectional view of a cylindrical battery 10 as an example of the embodiment.

[0009] 1, cylindrical battery 10 includes a cylindrical outer can 16 with a bottom including a bottom portion 16a and a side portion 16b, a sealing body 17 that closes the opening of outer can 16, and a gasket 18 that is interposed between outer can 16 and sealing body 17. Cylindrical battery 10 also includes an electrode assembly 14 and an electrolyte housed in outer can 16. Electrode assembly 14 includes a positive electrode 11, a negative electrode 12, and a separator 13, and has a structure in which positive electrode 11 and negative electrode 12 are spirally wound with separator 13 interposed therebetween.

[0010] In this specification, for ease of explanation, the direction along the axial direction of the outer can 16 is referred to as the "vertical direction or up-down direction," with the sealing body 17 side of the cylindrical battery 10 (the opening side of the outer can 16) being the top and the bottom surface 16a side of the outer can 16 being the bottom.

[0011] 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 be made of a foil of a metal, such as aluminum or an aluminum alloy, that is stable within the potential range of the positive electrode 11, or a film with such a metal disposed on the 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 is used as the positive electrode active material.

[0012] 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 be made of a foil of a metal such as copper or a copper alloy that is stable within the potential range of the negative electrode 12, or a film with such a metal disposed on the surface layer. 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 can be, for example, graphite or a silicon-containing compound.

[0013] The electrolyte may be an aqueous electrolyte or a non-aqueous electrolyte. It may also be a liquid electrolyte or a solid electrolyte. In this embodiment, a non-aqueous electrolyte is used. The non-aqueous electrolyte includes a non-aqueous solvent and an electrolyte salt dissolved in the non-aqueous solvent. Examples of the non-aqueous solvent that can be used include esters, ethers, nitriles, amides, and mixed solvents of two or more of these. The non-aqueous solvent may contain a halogen-substituted compound in which at least a portion of the hydrogen atoms in these solvents are substituted with halogen atoms such as fluorine. The electrolyte salt may be, for example, a lithium salt such as LiPF6.

[0014] The cylindrical battery 10 includes insulating plates 19 and 20 disposed above and below the electrode assembly 14. In the example shown in FIG. 1 , a positive electrode lead 21 connected to the positive electrode 11 passes through a through-hole in the insulating plate 19 and extends toward the sealing body 17, and a negative electrode lead 22 connected to the negative electrode 12 passes outside the insulating plate 20 and extends toward the bottom 16a of the outer can 16. The positive electrode lead 21 is connected by welding or the like to an internal terminal plate 25, which is the bottom plate of the sealing body 17, and a rupture plate 26 of the sealing body 17, which is electrically connected to the internal terminal plate 25, serves as the positive electrode external terminal. The negative electrode lead 22 is connected by welding or the like to the inner surface of the bottom 16a of the outer can 16, and the outer can 16 serves as the negative electrode external terminal.

[0015] The outer can 16 is a metal container that is open at one axial end (top end), with a disk-shaped bottom portion 16a and a cylindrical side portion 16b that follows the outer periphery of the bottom portion 16a. The sealing body 17 is formed in a disk shape that corresponds to the shape of the opening of the outer can 16. The gasket 18 is an annular resin member that ensures the sealing of the inside of the battery and also ensures electrical insulation between the outer can 16 and the sealing body 17.

[0016] In outer can 16, the edge of the opening is bent inward to form a crimped portion 31 that presses down on sealing body 17 via gasket 18. In addition, outer can 16 has side surface portion 16b that protrudes inward from the outside to form a grooved portion 30 that supports sealing body 17 via gasket 18. Grooved portion 30 is formed in an annular shape along the circumferential direction of outer can 16 by spinning side surface portion 16b from the outside.

[0017] The crimping portion 31 is formed by bending the opening edge (upper end) of the outer can 16 inward, and faces the grooved portion 30 with the sealing body 17 and gasket 18 between them, and holds the sealing body 17 together with the grooved portion 30. Like the grooved portion 30, the crimping portion 31 is formed in an annular shape along the circumferential direction of the outer can 16, and presses the peripheral edge of the sealing body 17 from above with the gasket 18 between them. As will be described in more detail below, the crimping portion 31 has a small bent portion 34 formed in the middle.

[0018] The sealing body 17 is a disc-shaped member equipped with a current interruption mechanism. The sealing body 17 has a structure in which, from the electrode body 14 side, an internal terminal plate 25, an insulating plate 27, and a rupture plate 26 are stacked. The internal terminal plate 25 is a metal plate including an annular portion 25a to which the positive electrode lead 21 is connected and a thin-walled central portion 25b that is separated from the annular portion 25a when the internal pressure of the battery exceeds a predetermined threshold. An air vent 25c is formed in the annular portion 25a.

[0019] Rupture plate 26 is disposed opposite internal terminal plate 25 with insulating plate 27 sandwiched therebetween. Insulating plate 27 has opening 27a formed in its radial center and vent hole 27b formed in a portion overlapping vent hole 25c of internal terminal plate 25. Rupture plate 26 has valve portion 26a that ruptures when the internal pressure of the battery exceeds a predetermined threshold, and valve portion 26a is connected to central portion 25b of internal terminal plate 25 via opening 27a of insulating plate 27 by welding or the like. Insulating plate 27 insulates portions other than the connection portion between annular portion 25a and central portion 25b of valve portion 26a.

[0020] The valve portion 26a is formed in the radial center of the rupture plate 26, including a lower convex portion that protrudes toward the inside of the battery and a thin-walled portion formed around the lower convex portion. In a cylindrical battery 10, the internal terminal plate 25, to which the positive electrode lead 21 is connected, is electrically connected to the rupture plate 26, thereby forming a current path connecting the electrode body 14 to the rupture plate 26. When an abnormality occurs in the battery and the internal pressure increases, the internal terminal plate 25 breaks, the central portion 25b is separated from the annular portion 25a, and the valve portion 26a deforms so that it protrudes toward the outside of the battery. This interrupts the current path. If the internal pressure of the battery increases further, the valve portion 26a breaks, forming a gas outlet.

[0021] The structure of the sealing body is not limited to the structure shown in FIG. 1. The sealing body may have a laminated structure including two valve bodies, or may have a convex sealing body cap covering the valve bodies. Alternatively, 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 serves as the negative electrode external terminal, and the outer can serves as the positive electrode external terminal.

[0022] For example, multiple cylindrical batteries 10 are connected in series to form a module. In a battery module including multiple cylindrical batteries 10, the external leads are connected to the crimped portion 31 and the sealing body 17 of the outer can 16 by welding or other means. Connecting the external leads to the crimped portion 31 allows for a more compact module compared to connecting the external leads to the bottom surface 16a of the outer can 16. With the cylindrical battery 10, the crimped portion 31 can be extended radially inward of the outer can 16, ensuring a sufficient external lead connection area at the crimped portion 31 and improving lead connection workability. The external leads are preferably welded to the second region 33 (see Figure 2, described below), which is the tip end portion of the crimped portion 31.

[0023] The grooved portion 30 and the crimped portion 31 of the outer can 16 will be described in detail below with reference to Figures 2 and 3. Figure 2 is an enlarged view of the grooved portion 30, the crimped portion 31, and a portion of the sealing body 17 in Figure 1, and Figure 3 is an enlarged view of the crimped portion 31.

[0024] As shown in FIG. 2, the grooved portion 30 has a generally U-shaped cross section and supports the sealing body 17 on its upper surface. The length L1 of the grooved portion 30 is, for example, 0.5 to 3 mm. Here, the length L1 of the grooved portion 30 refers to the length along the radial direction of the outer can 16 from the side surface portion 16b to the inner end 30a of the grooved portion 30. If the length L1 of the grooved portion 30 is within this range, the sealing body 17 can be stably supported while ensuring the mechanical strength of the outer can 16. Note that, if the length L1 of the grooved portion 30 is increased, deformation of the sealing body 17 can be suppressed even if the length L2 of the crimping portion 31 is increased; however, an increase in L1 poses the problem of a reduction in the internal space of the battery.

[0025] As described above, the crimped portion 31 is a portion bent inwardly of the outer can 16 and presses the peripheral edge of the sealing body 17 from above with the gasket 18 interposed therebetween. The crimped portion 31 is formed by bending the opening edge (upper end) of the outer can 16 inwardly of the outer can 16 so that it faces the grooved portion 30 with the sealing body 17 and gasket 18 interposed therebetween. In the cylindrical battery 10, the crimped portion 31 compresses the gasket 18, thereby ensuring airtightness inside the battery.

[0026] Furthermore, it is preferable that the crimped portion 31 has a uniform thickness. That is, it is preferable that the crimped portion 31 does not have large irregularities, grooves, steps, or the like, and that there are no thin-walled portions where the thickness is locally thin. In this case, the strength of the crimped portion 31 can be sufficiently ensured, and it is possible to prevent, for example, cracks from occurring in the exterior can 16 due to an impact applied to the battery.

[0027] The crimping portion 31 is inclined downward so that the distance from the outer surface of the sealing body 17 decreases toward the inside of the outer can 16, and includes a first region 32, which is a base-side portion that strongly compresses the gasket 18 to the extent that the sealing body 17 does not deform. The first region 32 has a rounded portion that curves significantly toward the outside of the outer can 16 near the base end 32a, which is the boundary position with the portion of the side surface 16b that runs along the vertical direction (i.e., the base of the crimping portion 31), and extends from the rounded portion toward the inside of the outer can 16 in the radial direction. The crimping portion 31, particularly the first region 32, strongly compresses the gasket 18, thereby ensuring good sealing inside the battery.

[0028] The crimped portion 31 includes a second region 33, which is a tip portion formed parallel to the bottom surface 16a of the outer can 16 and along the outer surface of the sealing body 17 in the radial direction of the outer can 16. In the example shown in FIG. 2, a bent portion 34 is present in the middle of the crimped portion 31, and the crimped portion 31 is formed parallel to the bottom surface 16a from the bent portion 34 to the tip 33a. By forming this second region 33, the pressure applied to the sealing body 17 by the crimped portion 31 is reduced, preventing deformation of the sealing body 17 even if the crimped portion 31 is extended. Furthermore, the external lead is welded to the second region 33, and the presence of the flat and long second region 33 improves the workability of lead connection. Note that in conventional cylindrical batteries, the crimped portion slopes downward from the rounded portion to the tip.

[0029] Bent portion 34 is the boundary between first region 32, which slopes downward, and second region 33, which is parallel to bottom surface portion 16a, and is a portion where the extension direction of crimped portion 31 changes. Bent portion 34 is formed by slightly bending the middle portion of crimped portion 31 so as to be convex toward sealing body 17. In this embodiment, bent portion 34 is formed closer to tip end 33a than base end 32a, but bent portion 34 may be formed closer to base end 32a or at a position approximately equidistant from base end 32a and tip end 33a.

[0030] 3, second region 33 of crimped portion 31 may be inclined upward so that the distance from sealing member 17 increases toward tip 33a. In this case, the inclination direction of crimped portion 31 changes from downward to upward at bent portion 34. Note that second region 33 may be inclined downward like first region 32, but in this case, second region 33 is inclined at a smaller angle toward sealing member 17 than first region 32.

[0031] As a specific example, in a vertical cross section of the outer can 16, the angle θ1 formed by an imaginary line α parallel to the bottom surface 16a of the outer can 16 and an imaginary line β along the second region 33 of the crimped portion 31 is preferably within a range of ±3°. Here, a positive angle θ1 means that the second region 33 is inclined upward toward the tip 33a, and a negative angle θ1 means that the second region 33 is inclined downward toward the tip 33a. Furthermore, when the second region 33 is parallel to the bottom surface 16a, the angle θ1 is 0°.

[0032] If angle θ1 is ±3°, deformation of sealing body 17 can be more reliably suppressed. Angle θ1 is more preferably −1.5 to 3°, and particularly preferably 0 to 3°. On the other hand, if angle θ1 is greater than +3°, problems may occur, such as reduced workability in connecting an external lead, or reduced sealing performance inside the battery due to excessively weak compression of gasket 18 on the side of tip 33a of crimped portion 31.

[0033] Furthermore, in the vertical cross section of outer can 16, the angle θ2 formed by an imaginary line α parallel to bottom surface portion 16a of outer can 16 and an imaginary line γ along the downwardly sloping portion of first region 32 is preferably 5 to 30°, more preferably 5 to 25°, and particularly preferably 5 to 20°. When angle θ2 is within this range, deformation of sealing body 17 is suppressed, and it is easy to strongly compress gasket 18 and ensure good sealing of the inside of the battery.

[0034] 2, the length L2 of the crimped portion 31 is preferably equal to or greater than the length L1 of the grooved portion 30. That is, the crimped portion 31 preferably extends radially inward of the outer can 16 beyond the inner end 30a of the grooved portion 30. In this case, a sufficient connection area for the external lead at the crimped portion 31 can be ensured, further improving the workability of lead connection. The length L1 of the crimped portion 31 is, for example, 1.05 to 2 times, and preferably 1.1 to 1.5 times, the length L2 of the grooved portion 30. An example of the length L2 is 1.5 to 3 mm.

[0035] The bent portion 34 is formed in a range facing the grooved portion 30. In other words, the bent portion 34 is formed in the crimped portion 31 closer to the base end 32a than the position where the bent portion 34 overlaps with the inner end 30a of the grooved portion 30 in the vertical direction. In this case, even if the crimped portion 31 is extended long, deformation of the sealing body 17 can be easily suppressed.

[0036] The crimped portion 31 is formed, for example, by reducing the diameter of only a region of a predetermined length (for example, 1 mm) from the top end of the outer can 16, inserting the sealing body 17 into the outer can 16, and then using a crimping die to plastically process the top end of the outer can 16 to crimp it to the sealing body 17. By bending the reduced diameter portion inward or outward at a predetermined angle during the reduction process, the inclination angle θ1 of the second region 33 can be freely adjusted.

[0037] The shape of the crimped portion 31 may be machined at an early stage of manufacturing the outer can 16. Alternatively, the upper end of the outer can 16 may be plastically machined so that only the rounded portion of the crimped portion 31 is the portion where the crimping die comes into contact with the outer can 16. In this case, for example, the tip 33a side springs back after crimping, forming the bent portion 34. Alternatively, the tip 33a may be additionally machined after crimping to machine the shape of the crimped portion 31.

[0038] As described above, in the cylindrical battery 10, the crimped portion 31 extends radially inward of the outer can 16 beyond the grooved portion 30. The crimped portion 31 has a bent portion 34, and the second region 33, which is the tip portion, is gently inclined within an angle range of ±3° relative to the bottom surface 16a of the outer can 16, or is formed parallel to the bottom surface 16a. Therefore, even if the crimped portion 31 is extended, deformation of the sealing body 17 due to pressure from the crimped portion 31 is suppressed. The cylindrical battery 10 can ensure a sufficient connection area for the external lead at the crimped portion 31 without causing a decrease in performance due to deformation of the sealing body 17, improving the workability of lead connection when modularizing the cylindrical battery 10. [Explanation of symbols]

[0039] 10 cylindrical battery, 11 positive electrode, 12 negative electrode, 13 separator, 14 electrode body, 16 Outer can, 16a bottom portion, 16b side portion, 17 sealing body, 18 gasket, 19, 20 insulating plate, 21 positive electrode lead, 22 negative electrode lead, 25 internal terminal plate, 25a annular portion, 25b central portion, 25c vent hole, 26 rupture plate, 26a valve portion, 27 insulating plate, 27a opening, 27b vent hole, 30 grooved portion, 30a inner end, 31 crimped portion, 32 first region, 32a base end, 33 second region, 33a tip, 34 bent portion

Claims

1. a cylindrical outer can with a bottom; a sealing body that closes the opening of the outer can; a gasket interposed between the outer can and the sealing body; Equipped with The outer can has an edge portion of the opening bent inward to form a crimping portion that presses the sealing body via the gasket, the crimping portion includes a base end portion that is inclined toward the inside of the exterior can so that the distance between the crimping portion and the sealing body becomes smaller, and a front end portion that is inclined at a smaller angle toward the sealing body than the base end portion, or that is parallel to a bottom surface of the exterior can, or that is inclined so that the distance between the crimping portion and the sealing body becomes larger toward the front end, The gasket is compressed at a portion facing a region extending from the base end portion to the tip end portion of the crimping portion.

2. the outer can has a grooved portion formed opposite the crimping portion across the sealing body and supporting the sealing body, The cylindrical battery according to claim 1 , wherein the length of the crimping portion is equal to or greater than the length of the grooved portion.

3. 3. The cylindrical battery according to claim 1, wherein, in a vertical cross section of the outer can, an angle θ formed by an imaginary line α parallel to a bottom surface of the outer can and an imaginary line β along the tip side portion of the crimped portion is within a range of ±3°.

4. The cylindrical battery according to any one of claims 1 to 3, wherein the crimped portion has a constant thickness.

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