Cylindrical battery

Abstract

The purpose of the present disclosure is to provide a cylindrical battery capable of suppressing the deformation of a sealing body while extending a caulking portion. A cylindrical battery as an example of an embodiment comprises: an outer can having a bottomed cylindrical shape; a sealing body that blocks an opening of the outer can; and a gasket that is interposed between the outer can and the sealing body. In the outer can, an edge forming an opening is bent inward and presses the caulking portion of the sealing body through the gasket. The caulking portion includes: a base end side portion that is inclined toward the inner side of the outer can and the gap with the sealing body becomes smaller; and a front end side portion that is inclined toward the sealing body at a smaller angle than the base end side portion, or is parallel to the bottom portion of the outer can, or is inclined toward the front end and the gap with the sealing body becomes larger.

Description

Technical Field

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

[0002] In the past, it is known that there is a cylindrical battery having a bottomed cylindrical outer can, a sealing body that blocks the opening of the outer can, and a gasket between the outer can and the sealing body (for example, refer to patent documents 1 and 2). Generally speaking, the edge of the opening formed in the outer can is bent inward and presses the caulking portion of the sealing body through the gasket. In addition, in a cylindrical battery, for example, the positive lead is connected to the inner surface of the sealing body, and the sealing body becomes the positive external terminal, and the negative lead is connected to the inner surface of the outer can, and the outer can becomes the negative external terminal.

[0003] Prior Art Literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Publication No. 2009-152031

[0006] Patent Document 2: JP 2010-512638 Summary of the invention

[0007] -Problems to be solved by the invention-

[0008] However, cylindrical batteries have multiple electrical connections and are modularized, and the external lead is connected to the positive external terminal and the negative external terminal. In this case, the external lead is sometimes connected to the crimping portion close to the sealing body in the outer can, which serves as the negative external terminal, for the purpose of miniaturization of the battery module. In this case, in order to increase the connection area of ​​the external lead and improve the operability of the lead connection, it is considered to extend the crimping portion longer, but if the crimping portion is simply extended, the sealing body is subjected to greater pressure from the crimping portion and is easily deformed. If the sealing body is deformed, there will be a greater deviation in the working pressure of the safety valve provided on the sealing body, and there will be undesirable conditions such as unstable connection position when the external lead is connected to the sealing body.

[0009] -Methods for solving problems-

[0010] A cylindrical battery as one aspect of the present disclosure is characterized in that it comprises: an outer can having a bottomed cylindrical shape; a sealing body that blocks the opening of the outer can; and a gasket that is interposed between the outer can and the sealing body, wherein an edge of the opening in the outer can is bent inwardly and presses a caulking portion of the sealing body via the gasket, the caulking portion comprising: a base end side portion that is inclined toward the inner side of the outer can and has a smaller gap with the sealing body; and a front end side portion that is inclined toward the sealing body at an angle smaller than that of the base end side portion, or is parallel to the bottom portion of the outer can, or is inclined toward the front end and has a larger gap with the sealing body.

[0011] -Effects of the Invention-

[0012] According to the cylindrical battery as one mode of the present disclosure, the crimping portion can be extended longer while suppressing the deformation of the sealing body. Thus, the performance degradation caused by the deformation of the sealing body will not occur, the connection area of ​​the external lead in the crimping portion can be fully ensured, and the workability of the lead connection is improved when the cylindrical battery is modularized. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0014] Figure 2 yes Figure 1 An enlarged view of a portion of the groove, caulking and sealing body of the outer can.

[0015] Figure 3 It is a figure for demonstrating the structure of a caulking part. DETAILED DESCRIPTION

[0016] Hereinafter, an example of an embodiment of a cylindrical battery according to the present disclosure will be described in detail with reference to the drawings. Figure 1 It is a cross-sectional view of a cylindrical battery 10 as an example of the embodiment.

[0017] like Figure 1 As shown, the cylindrical battery 10 includes: a bottomed cylindrical outer can 16 including a bottom portion 16a and a side portion 16b; a sealing body 17 that blocks the opening of the outer can 16; and a gasket 18 interposed between the outer can 16 and the sealing body 17. In addition, the cylindrical battery 10 includes an electrode body 14 and an electrolyte housed in the outer can 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 with the separator 13 interposed therebetween.

[0018] In this specification, for the sake of convenience, the direction along the axial direction of the outer can 16 is set as the "longitudinal or up and down direction", the sealing body 17 side of the cylindrical battery 10 (the opening side of the outer can 16) is set as the top, and the bottom portion 16a side of the outer can 16 is set as the bottom.

[0019] 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 aluminum alloy that is stable within the potential range of the positive electrode 11, or a film that arranges the metal on the surface. The positive electrode mixture layer includes 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 surfaces of the positive electrode core. For example, a lithium transition metal composite oxide is used as the positive electrode active material.

[0020] 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 that arranges the metal on the surface. The negative electrode mixture layer includes 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, or the like.

[0021] The electrolyte may be an aqueous electrolyte or a non-aqueous electrolyte. In addition, it may be any of a liquid electrolyte and a solid electrolyte. In the present 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. As the non-aqueous solvent, for example, esters, ethers, nitriles, amides, and mixed solvents of two or more of these solvents can be used. 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. For example, LiPF is used as the electrolyte salt. 6 And other lithium salts.

[0022] The cylindrical battery 10 includes insulating plates 19 and 20 disposed above and below the electrode body 14, respectively. Figure 1 In the example shown, the positive electrode lead 21 connected to the positive electrode 11 extends to the sealing body 17 side through the through hole of the insulating plate 19, and the negative electrode lead 22 connected to the negative electrode 12 extends to the bottom portion 16a side of the outer can 16 through the outside of the insulating plate 20. The positive electrode lead 21 is connected to the internal terminal plate 25 as the bottom plate of the sealing body 17 by welding or the like, and the burst plate 26 of the sealing body 17 electrically connected to the internal terminal plate 25 serves as the positive electrode external terminal. The negative electrode lead 22 is connected to the inner surface of the bottom portion 16a of the outer can 16 by welding or the like, and the outer can 16 serves as the negative electrode external terminal.

[0023] The outer can 16 is a metal container with one axial end (upper end) open, the bottom portion 16a is disc-shaped, and the side portion 16b is formed in a cylindrical shape along the outer peripheral edge of the bottom portion 16a. The sealing body 17 is formed in a disc shape corresponding to the shape of the opening of the outer can 16. The gasket 18 is a resin annular member, which ensures the airtightness of the battery interior and ensures the electrical insulation of the outer can 16 and the sealing body 17.

[0024] The outer can 16 is formed with a caulking portion 31 that is bent inwardly at the edge of the opening and presses the sealing body 17 via the gasket 18. In addition, the outer can 16 is formed with a groove portion 30 that is formed by the side portion 16b extending from the outside to the inside and supports the sealing body 17 via the gasket 18. The groove portion 30 is formed in an annular shape along the circumferential direction of the outer can 16 by spinning from the outside of the side portion 16b.

[0025] The caulking portion 31 is formed by bending the opening edge (upper end) of the outer can 16 inward, and is opposed to the groove portion 30 via the sealing body 17 and the gasket 18, and clamps the sealing body 17 together with the groove portion 30. The caulking portion 31 is formed in an annular shape along the circumference of the outer can 16 similarly to the groove portion 30, and presses the peripheral edge of the sealing body 17 from above via the gasket 18. The details will be described later, and a small bent portion 34 is formed in the middle of the caulking portion 31.

[0026] The sealing body 17 is a disc-shaped member having a current interruption mechanism. The sealing body 17 has a structure in which an internal terminal plate 25, an insulating plate 27, and a bursting plate 26 are stacked in order from the electrode body 14 side. The internal terminal plate 25 is a metal plate including an annular portion 25a to which the positive lead 21 is connected; and a thin-walled central portion 25b that is cut off from the annular portion 25a when the internal pressure of the battery exceeds a given threshold. A vent hole 25c is formed in the annular portion 25a.

[0027] The bursting plate 26 is disposed opposite to the internal terminal plate 25 with the insulating plate 27 sandwiched therebetween. An opening 27a is formed in the radial center of the insulating plate 27, and a vent hole 27b is formed in the portion of the internal terminal plate 25 overlapping with the vent hole 25c. The bursting plate 26 has a valve portion 26a that breaks when the internal pressure of the battery exceeds a given threshold, and the valve portion 26a is connected to the central portion 25b of the internal terminal plate 25 by welding or the like through the opening 27a of the insulating plate 27. The insulating plate 27 insulates the portion other than the connection portion between the annular portion 25a and the central portion 25b of the valve portion 26a.

[0028] The valve portion 26a 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 burst plate 26. In the cylindrical battery 10, the internal terminal plate 25 connected to the positive lead 21 is electrically connected to the burst plate 26, thereby forming a current path from the electrode body 14 to the burst plate 26. If an abnormality occurs in the battery and the internal pressure rises, the internal terminal plate 25 breaks, the central portion 25b is cut off from the annular portion 25a, and the valve portion 26a 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 battery further rises, the valve portion 26a breaks to form a gas discharge port.

[0029] In addition, the structure of the sealing body is not limited to Figure 1 The sealing body may have a laminated structure including two valve bodies, or may 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.

[0030] For example, a plurality of cylindrical batteries 10 are connected in series to be modularized. In a battery module including a plurality of cylindrical batteries 10, the external lead is connected to the crimping portion 31 and the sealing body 17 of the outer can 16 by welding or the like. When the external lead is connected to the crimping portion 31, the module can be miniaturized compared to the case where the external lead is connected to the bottom portion 16a of the outer can 16. According to the cylindrical battery 10, the crimping portion 31 can be extended radially inwardly of the outer can 16, so that the external lead connection area in the crimping portion 31 can be sufficiently ensured, thereby improving the workability of the lead connection. In addition, the external lead is preferably welded to the front end side portion of the crimping portion 31, that is, the second region 33 (see below). Figure 2 ).

[0031] Below, refer to Figure 2 and Figure 3 , the groove portion 30 and the caulking portion 31 of the outer can 16 are described in detail. Figure 2 yes Figure 1 An enlarged view of the groove portion 30, the caulking portion 31 and a portion of the sealing body 17, Figure 3 It is an enlarged view of the caulking portion 31 .

[0032] like Figure 2As shown, the cross-section of the groove portion 30 has a substantially U-shape, and the sealing body 17 is supported by the upper surface of the groove portion. The length L1 of the groove portion 30 is, for example, 0.5 to 3 mm. Here, the length L1 of the groove portion 30 refers to the length along the radial direction of the outer can 16 from the side portion 16b to the inner end 30a of the groove portion 30. If the length L1 of the groove portion 30 is within this range, the sealing body 17 can be stably supported while ensuring the mechanical strength of the outer can 16. In addition, if the length L1 of the groove portion 30 is extended, even if the length L2 of the caulking portion 31 is extended, the deformation of the sealing body 17 can be suppressed, but if L1 becomes longer, there is a problem such as a reduction in the internal space of the battery.

[0033] As described above, the caulking portion 31 is a portion bent toward the inside of the outer can 16, and is a portion that presses the peripheral edge of the sealing body 17 from above via the gasket 18. The caulking portion 31 is formed by bending the inner side of the outer can 16 so that the opening edge (upper end) of the outer can 16 faces the groove portion 30 via the sealing body 17 and the gasket 18. In the cylindrical battery 10, the caulking portion 31 compresses the gasket 18, thereby ensuring the airtightness of the inside of the battery.

[0034] In addition, the thickness of the caulking portion 31 is preferably constant. That is, it is preferred that no large concave-convex, groove, step difference, etc. is formed in the caulking portion 31, and no thin-walled portion where the thickness is locally thinned exists. In this case, the strength of the caulking portion 31 can be sufficiently ensured, and for example, cracks can be prevented from being generated in the outer can 16 due to impact applied to the battery.

[0035] The caulking portion 31 is inclined downward with the gap between the inner side of the outer can 16 and the outer surface of the sealing body 17 becoming smaller, and includes a first region 32 as a base end side portion that strongly compresses the gasket 18 within a range where the sealing body 17 does not deform. The first region 32 has an R portion that is greatly curved toward the outer side of the outer can 16 near the base end 32a at the boundary position with the part of the side portion 16b along the vertical direction (that is, the root of the caulking portion 31), and extends from the R portion to the radial inner side of the outer can 16. The gasket 18 is strongly compressed in the caulking portion 31, especially the first region 32, thereby ensuring good airtightness inside the battery.

[0036] The caulking portion 31 includes a second region 33 as a front end portion formed along the radial direction of the outer can 16 and along the outer surface of the sealing body 17 in parallel with the bottom surface portion 16a of the outer can 16. Figure 2In the example shown, there is a curved portion 34 in the middle of the caulking portion 31, and the curved portion 34 of the caulking portion 31 to the front end 33a is formed parallel to the bottom surface portion 16a. By forming such a second region 33, the pressure on the sealing body 17 from the caulking portion 31 is suppressed, and the deformation of the sealing body 17 can be prevented even if the caulking portion 31 is extended. In addition, although the external lead is welded to the second region 33, the existence of the flat and long second region 33 improves the workability of the lead connection. In addition, in the conventional ordinary cylindrical battery, the caulking portion is inclined downward from the R portion to the front end.

[0037] The curved portion 34 is a boundary portion between the first region 32 inclined downward and the second region 33 parallel to the bottom surface portion 16a, and is a portion where the direction in which the caulking portion 31 extends changes. The curved portion 34 is formed by slightly bending the middle portion of the caulking portion 31 so as to protrude toward the sealing body 17. In the present embodiment, the curved portion 34 is formed at a position closer to the front end 33a than the base end 32a, but the curved portion 34 may be formed at a position closer to the base end 32a, or may be formed at a position approximately equidistant from the base end 32a and the front end 33a.

[0038] like Figure 3 As shown in the figure, the second area 33 of the caulking portion 31 may be inclined upward so that the distance between the front end 33a and the sealing body 17 becomes larger. In this case, the inclination direction of the caulking portion 31 changes from the bottom to the top in the curved portion 34. In addition, the second area 33 may be inclined downward like the first area 32, but in this case, it is inclined toward the sealing body 17 side at a smaller angle than the first area 32.

[0039] As a specific example, in the longitudinal section of the outer can 16, it is preferred that the angle θ1 formed by the imaginary line α parallel to the bottom surface 16a of the outer can 16 and the imaginary line β along the second region 33 of the caulking portion 31 is within the range of ±3°. Here, the angle θ1 being + means that the second region 33 is inclined upward toward the front end 33a, and the angle θ1 being - means that the second region 33 is inclined downward toward the front end 33a. In addition, when the second region 33 is parallel to the bottom surface 16a, the angle θ1 is 0°.

[0040] If the angle θ1 is ±3°, the deformation of the sealing body 17 can be more reliably suppressed. The angle θ1 is more preferably -1.5 to 3°, and particularly preferably 0 to 3°. On the other hand, if the angle θ1 is larger than +3°, for example, the workability of the external lead connection is reduced, or the compression of the gasket 18 on the front end 33a side of the caulking portion 31 becomes too weak, thereby reducing the airtightness of the battery.

[0041] In addition, in the longitudinal section of the outer can 16, the angle θ2 formed by the imaginary line α parallel to the bottom portion 16a of the outer can 16 and the imaginary line γ along the downwardly inclined portion of the first region 32 is preferably 5 to 30°, more preferably 5 to 25°, and particularly preferably 5 to 20°. If the angle θ2 is within this range, the deformation of the sealing body 17 can be suppressed, and the gasket 18 can be easily compressed to ensure good sealing inside the battery.

[0042] like Figure 2 As shown, the length L2 of the caulking portion 31 is preferably greater than the length L1 of the groove portion 30. That is, the caulking portion 31 preferably extends radially inward of the outer can 16 relative to the inner end 30a of the groove portion 30. In this case, the connection area of ​​the external lead in the caulking portion 31 can be sufficiently ensured, and the workability of the lead connection is further improved. The length L1 of the caulking portion 31 is, for example, 1.05 to 2 times the length L2 of the groove portion 30, preferably 1.1 to 1.5 times. An example of the length L2 is 1.5 to 3 mm.

[0043] The bent portion 34 is formed within a range facing the groove portion 30. In other words, the bent portion 34 is formed on the caulking portion 31 closer to the base end 32a than the position overlapping with the inner end 30a of the groove portion 30 in the vertical direction. In this case, even if the caulking portion 31 is extended, deformation of the sealing body 17 can be easily suppressed.

[0044] The caulking portion 31 is formed, for example, by performing a diameter reduction process on only a region of a given length (e.g., 1 mm) from the upper end of the outer can 16, inserting the sealing body 17 into the outer can 16, and performing plastic working on the upper end of the outer can 16 with a caulking die to caulk the sealing body 17. During the diameter reduction process, the diameter reduction portion is bent at a given angle on the inside or outside, so that the inclination angle θ1 of the second region 33 can be freely adjusted.

[0045] In addition, the shape of the caulking portion 31 may be processed at the initial stage of manufacturing the outer can 16. In addition, only the portion where the caulking die contacts the outer can 16 may be used as the R portion of the caulking portion 31, and the upper end portion of the outer can 16 may be plastically processed. In this case, for example, after caulking, the front end 33a side rebounds to form the bent portion 34. In addition, even if the front end 33a is additionally processed after caulking, the shape of the caulking portion 31 can be processed.

[0046] As described above, in the cylindrical battery 10, the caulking portion 31 extends radially inward of the outer can 16 further than the groove portion 30. In addition, a curved portion 34 is formed in the caulking portion 31, and the second region 33 as the front end portion is gently inclined within an angle range of ±3° relative to the bottom portion 16a of the outer can 16, or is formed parallel to the bottom portion 16a. Therefore, even if the caulking portion 31 is extended longer, the deformation of the sealing body 17 caused by the pressure received from the caulking portion 31 can be suppressed. According to the cylindrical battery 10, the performance degradation caused by the deformation of the sealing body 17 will not occur, and the connection area of ​​the external lead in the caulking portion 31 can be fully ensured, and the workability of the lead connection is improved when the cylindrical battery 10 is modularized.

[0047] -Explanation of symbols-

[0048] 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 burst plate, 26a valve portion, 27 insulating plate, 27a opening, 27b vent hole, 30 groove portion, 30a inner end, 31 caulking portion, 32 first region, 32a base end, 33 second region, 33a front end, 34 bent portion.

Claims

1. A cylindrical battery comprising: The outer can is cylindrical with a bottom; A sealing body, which blocks the opening of the outer can; and A gasket is disposed between the outer can and the sealing body, In the outer can, the edge forming the opening is bent inward and presses the caulking portion of the sealing body through the gasket. The caulking portion comprises: The base end side portion is inclined toward the inner side of the outer can so that the distance between the base end portion and the sealing body becomes smaller; and a front end side portion that is inclined toward the sealing body at a smaller angle than the base end side portion.

2. The cylindrical battery according to claim 1, The outer can has a groove portion, the groove portion being formed to face the caulking portion across the sealing body and to support the sealing body. The length of the caulking portion is greater than the length of the groove portion.

3. The cylindrical battery according to claim 1 or 2, In the longitudinal section of the outer can, an angle θ formed by an imaginary line α parallel to the bottom surface portion of the outer can and an imaginary line β along the front end side portion of the caulked portion is within a range of −3°.

4. The cylindrical battery according to claim 1 or 2, The thickness of the caulking portion is constant.

5. A cylindrical battery comprising: The outer can is cylindrical with a bottom; A sealing body, which blocks the opening of the outer can; and A gasket is disposed between the outer can and the sealing body, In the outer can, the edge forming the opening is bent inward and presses the caulking portion of the sealing body through the gasket. The caulking portion comprises: The base end side portion is inclined toward the inner side of the outer can so that the distance between the base end portion and the sealing body becomes smaller; and a front end side portion which is inclined so as to increase the distance between the front end and the sealing body toward the front end, In the longitudinal section of the outer can, an angle θ formed by an imaginary line α parallel to the bottom surface portion of the outer can and an imaginary line β along the front end side portion of the caulked portion is within a range of +3°.

6. The cylindrical battery according to claim 5, The outer can has a groove portion, the groove portion being formed to face the caulking portion across the sealing body and to support the sealing body. The length of the caulking portion is greater than the length of the groove portion.

7. The cylindrical battery according to claim 5 or 6, The thickness of the caulking portion is constant.

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