Cylindrical battery

Abstract

A cylindrical battery exemplifying one embodiment comprises an electrode body, a bottomed cylindrical external can that accommodates the electrode body, a sealing body that blocks an opening of the external can, a gasket that is interposed between the external can and the sealing body, and an external terminal plate that is joined to the outer surface of the external can. The external terminal plate is a metal plate having a thick portion and a thin portion, and the thin portion is joined to an open edge of the external can.

Description

Technical Field

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

Background Art

[0002] A cylindrical battery generally includes a wound electrode body, a bottomed cylindrical outer can that houses the electrode body, and a sealing body that closes the opening of the outer can. The outer can has a caulking portion formed by bending the opening edge inward to press the sealing body through a gasket. Cylindrical batteries are characterized by being resistant to shock and easy to modularize. In applications that require a large capacity, a plurality of cylindrical batteries are electrically connected and modularized. At this time, leads for connecting the cylindrical batteries to each other are joined to the external terminals of the cylindrical batteries by laser welding or the like (see, for example, Patent Document 1).

[0003] In a cylindrical battery, for example, the sealing body serves as the positive electrode external terminal, and the outer can serves as the negative electrode external terminal. Patent Document 1 discloses a battery connection device that connects the top surface of the sealing body of the first cylindrical battery and the bottom of the outer can of the second cylindrical battery. In addition, a current collecting terminal on the negative electrode side may be welded to the caulking portion of the outer can close to the sealing body among the outer cans that are the negative electrode external terminals (see, for example, Patent Document 2). In this case, since each current collecting terminal on the positive electrode side and the negative electrode side can be arranged on one end side in the axial direction of the cylindrical battery, for example, the size of the battery module can be reduced.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] When welding leads to the crimped portion of the outer casing during the modularization of cylindrical batteries, ensuring a stable and reliable connection of the leads is not easy. To stabilize the lead connection, one might consider increasing the radial length of the crimped portion to increase the bonding area. However, in this case, the sealing body is strongly compressed from the crimped portion and becomes prone to deformation. As a result, problems such as increased variation in the operating pressure of the safety valve provided in the sealing body, or instability in the connection position when connecting the leads to the sealing body, may occur. [Means for solving the problem]

[0006] The cylindrical battery according to this disclosure comprises an electrode body, a bottomed cylindrical outer casing housing the electrode body, a sealing body that closes the opening of the outer casing, a gasket interposed between the outer casing and the sealing body, and an external terminal plate joined to the outer surface of the outer casing, wherein the external terminal plate is a metal plate having a thick portion and a thin portion, and the thin portion is joined to the opening edge of the outer casing. [Effects of the Invention]

[0007] The cylindrical battery described herein allows for stable lead connection during modularization while suppressing deformation of the sealing body. [Brief explanation of the drawing]

[0008] [Figure 1] This is a cross-sectional view of a cylindrical battery, which is an example of an embodiment. [Figure 2] This is a plan view of a cylindrical battery, which is an example of an embodiment. [Figure 3] This is an enlarged view of section A in Figure 1. [Figure 4] This figure shows a modified example of an external terminal board. [Figure 5] This figure shows a modified example of an external terminal board. [Figure 6] This figure shows a modified example of an external terminal board. [Modes for carrying out the invention]

[0009] Hereinafter, an example of an embodiment of the cylindrical battery according to this disclosure will be described in detail with reference to the drawings. The cylindrical battery according to this disclosure is not limited to the embodiments described below, and configurations that selectively combine the multiple embodiments and modifications described below are also included in this disclosure.

[0010] Figure 1 is a cross-sectional view of a cylindrical battery 10, which is an example of an embodiment. As shown in Figure 1, the cylindrical battery 10 comprises an electrode body 14, a bottomed cylindrical outer casing 16 that houses the electrode body 14, and a sealing body 17 that closes the opening of the outer casing 16. The outer casing 16 contains an electrolyte together with the electrode body 14. The electrolyte may be an aqueous electrolyte, but in this embodiment, a non-aqueous electrolyte is used. The outer casing 16 has grooves 22 formed in its side wall, and the sealing body 17 is supported by the grooves 22 and closes the opening of the outer casing 16. The outer casing 16 and the sealing body 17 together constitute a case 15 that has a substantially cylindrical shape as a whole. In the following description, for convenience, the sealing body 17 side of the cylindrical battery 10 will be considered the top, and the bottom side of the outer casing 16 will be considered the bottom.

[0011] The cylindrical battery 10 further includes a gasket 28 interposed between the outer casing 16 and the sealing body 17. The gasket 28 is a ring-shaped resin member attached to the outer circumference of the sealing body 17, ensuring insulation between the outer casing 16 and the sealing body 17. The gasket 28 also seals the gap between the outer casing 16 and the sealing body 17, thereby sealing the inside of the battery. The gasket 28 is made of, for example, polyolefin.

[0012] The cylindrical battery 10 further includes an external terminal plate 30 bonded to the outer surface of the outer casing 16. The external terminal plate 30 is a conductive member to which leads are connected, for example, to electrically connect multiple cylindrical batteries 10 to each other when modularizing them. As will be described in more detail later, the external terminal plate 30 is located on the upper surface of the case 15 and welded to the outer surface of the outer casing 16. The external terminal plate 30 is made of a metal, for example, with iron as the main component. For the leads, for example, metal plates or metal wires can be used.

[0013] Non-aqueous electrolytes comprise 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. Non-aqueous solvents may also 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 non-aqueous solvents include ethylene carbonate (EC), ethyl methyl carbonate (EMC), dimethyl carbonate (DMC), and mixtures thereof. Examples of electrolyte salts include lithium salts such as LiPF6. Note that non-aqueous electrolytes are not limited to liquid electrolytes and may also be solid electrolytes.

[0014] The electrode body 14 has a positive electrode 11, a negative electrode 12, and a separator 13, and has a wound structure in which the positive electrode 11 and the negative electrode 12 are wound in a spiral shape via the separator 13. The positive electrode 11, the negative electrode 12, and the separator 13 are all elongated strip-shaped bodies, and are alternately stacked in the radial direction of the electrode body 14 by being wound in a spiral shape. The negative electrode 12 is formed to be slightly larger in dimensions than the positive electrode 11 in order to prevent lithium deposition. That is, the negative electrode 12 is formed to be longer in the longitudinal and width directions than the positive electrode 11. The separator 13 is formed to be at least slightly larger in dimensions than the positive electrode 11, and for example, two separators are arranged so as to sandwich the positive electrode 11.

[0015] A positive electrode lead 20 and a negative electrode lead 21 are connected to the electrode body 14. In this embodiment, the positive electrode lead 20 electrically connects the positive electrode 11 to the sealing body 17, and the negative electrode lead 21 electrically connects the negative electrode 12 to the outer can 16. The sealing body 17 functions as the positive electrode external terminal, and the external terminal plate 30 joined to the outer can 16 functions as the negative electrode external terminal. In the example shown in Figure 1, the positive electrode lead 20 extends through the opening of the insulating plate 18 towards the sealing body 17, and the negative electrode lead 21 extends outside the insulating plate 19 towards the bottom of the outer can 16.

[0016] The positive electrode 11 has a positive electrode core body and a positive electrode mixture layer formed on at least one surface of the core body. For the positive electrode core body, a foil of a metal stable within the potential range of the positive electrode 11, such as aluminum or an aluminum alloy, or a film with such a metal disposed on the surface layer can be used. The positive electrode mixture layer preferably contains a positive electrode active material, a conductive agent such as acetylene black, and a binder such as polyvinylidene fluoride (PVdF), and is formed on both surfaces of the positive electrode core body. For the positive electrode active material, for example, a lithium transition metal composite oxide containing Ni, Co, Mn, Al, etc. is used. The positive electrode lead 20 is connected to the positive electrode 11, and is preferably directly joined to the positive electrode core body by ultrasonic welding or the like.

[0017] The negative electrode 12 has a negative electrode core body and a negative electrode mixture layer formed on at least one surface of the core body. For the negative electrode core body, a foil of a metal stable within the potential range of the negative electrode 12, such as copper or a copper alloy, or a film with such a metal disposed on the surface layer can be used. The negative electrode mixture layer preferably contains a negative electrode active material and a binder such as styrene-butadiene rubber (SBR) or PVdF, and is formed on both surfaces of the negative electrode core body. For the negative electrode active material, for example, graphite, a silicon-containing compound, etc. are used. The negative electrode lead 21 is preferably directly joined to the negative electrode core body by ultrasonic welding or the like. It is also possible to electrically connect the negative electrode 12 and the outer can 16 by bringing the negative electrode core body into contact with the inner surface of the outer can 16.

[0018] The outer can 16 is a bottomed cylindrical metal container with one end (upper end) in the axial direction open, and has a cylindrical side wall and a bottom that is circular in plan view. The outer can 16 is generally made of a metal mainly composed of iron, but may also be made of a metal mainly composed of aluminum or the like. An annular groove portion 22 is formed in the side wall of the outer can 16 over the entire circumferential length. The groove portion 22 is a part where a part of the side wall projects inward of the outer can 16, and is formed, for example, by spinning the side wall from the outside. The groove portion 22 is formed at a position a predetermined length away from the upper end of the outer can 16. The predetermined length is, for example, a length corresponding to 1 to 20% of the axial length of the outer can 16.

[0019] The sealing body 17 is fixed to the opening edge of the outer can 16 by being sandwiched between the groove insertion part 22 and the caulking part 29. In the present embodiment, the caulking part 29 is formed at the upper end of the outer can 16. The caulking part 29 is a part where the upper end of the outer can 16 is bent inward of the outer can 16 and caulked against the sealing body 17 disposed on the groove insertion part 22. The caulking part 29 is formed in an annular shape along the circumferential direction of the outer can 16. The caulking part 29 is inclined with respect to the radial direction of the outer can 16 so that, for example, the distance from the outside in the radial direction of the outer can 16 to the upper surface of the sealing body 17 becomes closer. Although it will be described in detail later, the gasket 28 is strongly compressed by the caulking part 29, and a part thereof extends from between the caulking part 29 and the sealing body 17 toward the central axis side of the case 15.

[0020] The sealing body 17 has a structure in which an internal terminal plate 23, a lower valve body 24, an insulating plate 25, an upper valve body 26, and a cap 27 are laminated in this order from the side of the electrode body 14. Each member constituting the sealing body 17 has, for example, a disc shape or a ring shape, and each member except the insulating plate 25 is electrically connected to each other. The cap 27 has a convex shape in which the central part in the radial direction protrudes outward. The convex part 27a of the cap 27 includes an annular inclined surface part and a flat top surface part surrounded by the inclined surface part. A plurality of ventilation holes 27b are formed in the top surface part.

[0021] The lower valve body 24, the insulating plate 25, and the upper valve body 26 constitute a current interruption mechanism. The lower valve body 24 and the upper valve body 26 are connected at the central parts of each, and the insulating plate 25 is interposed between the peripheral parts of each. In this case, when an abnormality occurs in the battery and the internal pressure rises, the lower valve body 24 is deformed and broken so as to push up the upper valve body 26 toward the cap 27 side, thereby interrupting the current path between the lower valve body 24 and the upper valve body 26. When the internal pressure further rises, the upper valve body 26 is broken, and gas is discharged from the ventilation holes 27b of the cap 27.

[0022] In this embodiment, the positive lead 20 is connected to the lower surface of the internal terminal plate 23 by welding or ultrasonic welding, and the cap 27, which is the top plate of the sealing body 17 electrically connected to the internal terminal plate 23, becomes the positive external terminal. The current collection terminal on the positive side is welded, for example, to the upper surface of the cap 27, more specifically to the top surface of the protrusion 27a. The negative lead 21 is connected to the inner surface of the bottom of the outer can 16 by welding or ultrasonic welding, and the external terminal plate 30 electrically connected to the outer can 16 becomes the negative external terminal. The current collection terminal on the negative side is welded, for example, to the upper surface of the external terminal plate 30.

[0023] The configuration of the external terminal board 30 and the insulating member 40 will be described in detail below with further reference to Figures 2 and 3. Figure 2 is a plan view of the cylindrical battery 10. Figure 3 is an enlarged view of section A in Figure 1.

[0024] As shown in Figures 1 to 3, the cylindrical battery 10 includes an external terminal plate 30 positioned on the upper surface of the case 15, with insulation from the sealing body 17 ensured. As described above, the external terminal plate 30 is joined to the outer casing 16 and functions as the negative electrode external terminal. In the cylindrical battery 10, both the cap 27 of the sealing body 17, which functions as the positive electrode external terminal, and the external terminal plate 30, which functions as the negative electrode external terminal, are positioned on the upper surface of the case 15. Therefore, when modularizing the cylindrical battery 10, leads can be connected to either the positive or negative electrode external terminal positioned on the upper surface of the case 15, making it possible to miniaturize the module and improve productivity.

[0025] The external terminal plate 30 is an annular metal plate in plan view having a thick portion 31 and a thin portion 32, with the thin portion 32 joined to the opening edge of the outer can 16. The thick portion 31 is the part of the external terminal plate 30 with the maximum thickness, and the thin portion 32 is the part of the external terminal plate 30 with the minimum thickness. In this embodiment, an inclined portion 33 is formed between the thick portion 31 and the thin portion 32, in which the thickness gradually decreases toward the radially outward direction of the external terminal plate 30.

[0026] The external terminal plate 30 is positioned on the upper surface of the case 15 so as not to protrude radially outward from the outer circumferential surface of the outer casing 16. In this case, the cylindrical battery 10 can be made smaller, and interference between the external terminal plate 30 and surrounding components in the battery module can be prevented. The outer diameter of the external terminal plate 30 is smaller than the outer diameter of the outer casing 16, and the external terminal plate 30 is positioned so as not to protrude from the upper surface of the case 15. In this embodiment, the thin-walled portion 32 of the external terminal plate 30 is joined to the crimped portion 29 that constitutes the outer circumferential edge of the upper surface of the case 15.

[0027] The external terminal plate 30 has an opening 34 in its radial center. The opening 34 has, for example, a circular shape in plan view and is formed to penetrate the external terminal plate 30 in the thickness direction. As described above, the cap 27 has a circular projection 27a in plan view that protrudes upward. The opening 34 is a hole for the projection 27a to pass through and has, for example, a diameter larger than the diameter of the projection 27a. The projection 27a protrudes upward through the opening 34, and the top surface of the projection 27a is located at the upper end of the cylindrical battery 10.

[0028] The thickened portion 31 is formed in an annular shape along the periphery of the opening 34 with a predetermined radial length (hereinafter sometimes referred to as "width"). Preferably, the thickened portion 31 is formed with a substantially constant width over the entire circumferential length of the external terminal plate 30. The thickened portion 31, the inclined portion 33, and the thinned portion 32 are arranged in this order from the inner circumferential side of the external terminal plate 30, and all are formed in an annular shape. Preferably, the thinned portion 32 and the inclined portion 33 are formed with a substantially constant width over the entire circumferential length of the external terminal plate 30, similar to the thickened portion 31.

[0029] The optimal thickness of the thick-walled portion 31 and the thin-walled portion 32, and the relationship between the thicknesses of each portion, vary depending on the material of the external terminal plate 30, but one example of the ratio of the thickness of the thin-walled portion 32 to the thickness of the thick-walled portion 31 is 0.5 to 0.7 times. The external terminal plate 30 is made of, for example, iron or an iron alloy such as stainless steel. The thickness of the thick-walled portion 31 is set based on the load acting on the thick-walled portion 31 when welding the current collection terminals, the strength of the material, etc. The thick-walled portion 31 and the thin-walled portion 32 are arranged side by side in the radial direction of the external terminal plate 30, and their respective surfaces (top and bottom surfaces) are parallel to each other.

[0030] The thickness of the thin-walled portion 32 is preferably less than or equal to the thickness of the portion of the outer can 16 to which the thin-walled portion 32 is joined. The outer can 16 and the thin-walled portion 32 are, for example, laser welded, but by setting the thickness of the thin-walled portion 32 to be less than or equal to the thickness of the outer can 16, the laser output can be suppressed, and the generation of spatter and the thermal impact on the gasket 28 can be effectively suppressed. In this embodiment, the thin-walled portion 32 is laser welded to the crimped portion 29 of the outer can 16. An example of the ratio of the thickness of the thin-walled portion 32 to the thickness of the crimped portion 29 is 0.5 to 0.8 times.

[0031] The relationship between the thickness of the thick portion 31 and the crimped portion 29 is not particularly limited, but in this embodiment, the thickness of the thick portion 31 is greater than the thickness of the crimped portion 29. That is, the relationship is: thickness of thin portion 32 < thickness of crimped portion 29 < thickness of thick portion 31. It is preferable that the thick portion 31 is formed with a substantially constant thickness along the entire circumferential length of the external terminal plate 30. The same applies to the thin portion 32.

[0032] The inclined portion 33 is a part in which the thickness gradually decreases toward the radially outward direction, and the upper and lower surfaces of the inclined portion 33 are gently inclined with respect to the radial direction of the external terminal plate 30. In this case, the change in the thickness of the external terminal plate 30 is gradual, and no step-like difference is formed between the thick portion 31 and the thin portion 32, thus improving the load-bearing capacity of the external terminal plate 30. The upper and lower surfaces of the inclined portion 33 are inclined so that they gradually get closer to each other toward the radially outward direction.

[0033] The inclination angles of the upper and lower surfaces of the radially inclined portion 33 of the external terminal plate 30 may be different from each other, but in this embodiment they are substantially the same. The center in the thickness direction of the thick portion 31 and the center in the thickness direction of the thin portion 32 are aligned in the radial direction of the external terminal plate 30. In this case, the upper and lower surfaces of the external terminal plate 30 have the same shape, and there is no need to distinguish between the front and back during use. Furthermore, moldability is also good.

[0034] The radial lengths (widths) of the thick-walled portion 31, the thin-walled portion 32, and the inclined portion 33 are not particularly limited, but it is preferable that the boundary between the thin-walled portion 32 and the inclined portion 33, in other words, the radially inner end of the thin-walled portion 32, is located closer to the central axis of the case 15 than the tip of the crimping portion 29. In this case, a sufficient joining area between the crimping portion 29 and the thin-walled portion 32 can be secured, and interference between the inclined portion 33 or the thick-walled portion 31 and the crimping portion 29 can be prevented more reliably. In this embodiment, the relationship is that the width of the inclined portion 33 < the width of the thick-walled portion 31 < the width of the thin-walled portion 32, but for example, the width of the thick-walled portion 31 may be greater than the width of the thin-walled portion 32.

[0035] Preferably, multiple welds between the crimping portion 29 and the external terminal plate 30 are formed by laser welding at predetermined intervals in the circumferential direction of the external terminal plate 30. Preferably, the predetermined intervals are substantially equal. In the example shown in Figure 2, four welds are formed at equal intervals in the circumferential direction, but the number of welds is not particularly limited. The number and area of ​​the welds are set, for example, taking into consideration the joint strength and resistance. Generally, the larger the welding area, the higher the joint strength and the lower the resistance. It is also possible to form welds continuously along the circumferential direction of the external terminal plate 30.

[0036] The cylindrical battery 10 further includes an insulating member 40 positioned on the upper surface of the case 15 to prevent electrical connection between the sealing body 17 and the external terminal plate 30. The insulating member 40 is a resin member with an annular shape in plan view, positioned between the sealing body 17 and the external terminal plate 30. The insulating member 40 is made of, for example, polyolefin. It is preferable that the insulating member 40 is positioned on the central axis side of the case 15, with a gap between it and the tip of the crimping portion 29, so as not to interfere with the welding of the crimping portion 29 of the outer casing 16 and the external terminal plate 30.

[0037] The insulating member 40 has a base portion 41 that abuts against the upper surface of the sealing body 17 and the lower surface of the thickened portion 31 of the external terminal plate 30. The base portion 41 is preferably formed in a flat annular shape and has a substantially constant width along the entire circumferential length of the insulating member 40. The thickness of the base portion 41 is not particularly limited, but in this embodiment it is greater than the thickness of the thickened portion 31. Since the base portion 41 abuts against the sealing body 17 and the thickened portion 31 and is positioned to support the thickened portion 31, the current collector terminal can be stably welded to the thickened portion 31.

[0038] The insulating member 40 has an opening 44 in its radial center. The opening 44 has, for example, a circular shape in plan view and is formed to penetrate the insulating member 40 in the thickness direction. The opening 44 is a hole for passing through the protrusion 27a of the cap 27, and the periphery of the opening 44 has a shape that allows it to closely adhere to the slope of the protrusion 27a. Preferably, the diameter of the opening 44 gradually decreases towards the top, and the periphery of the opening 44 abuts against the slope of the protrusion 27a along its entire circumferential length. In this case, the insulating member 40 can be stably positioned on the upper surface of the case 15.

[0039] The insulating member 40 is positioned to overlap with the extended portion 28a of the gasket 28, which extends from between the crimped portion 29 and the sealing body 17 toward the central axis of the case 15. The insulating member 40 has a first projection 42 that covers the upper surface of the gasket 28. The first projection 42 is formed in an annular shape, projecting radially outward from the outer peripheral edge of the base portion 41.

[0040] The first protrusion 42 is thinner than the insulating member 40, and the upper surface of the first protrusion 42 is formed flush with the upper surface of the base portion 41. Preferably, the first protrusion 42 overlaps the gasket 28 along the entire circumferential length of the insulating member 40. In this case, the entire upper surface of the sealing body 17 facing the external terminal plate 30 is covered by the gasket 28 and the insulating member 40, improving insulation performance.

[0041] Furthermore, the insulating member 40 has a second projection 43 that protrudes upward from the inner peripheral edge of the base portion 41 and is formed in an annular shape. The second projection 43 is formed in a hook shape in cross-section so as to wrap around to the upper surface of the external terminal plate 30. The second projection 43 is interposed between the convex portion 27a of the cap 27 and the inner peripheral edge of the external terminal plate 30, preventing contact between the convex portion 27a and the external terminal plate 30. The tip of the second projection 43 is formed substantially parallel to the base portion 41, with a gap between it and the upper surface of the base portion 41. The inner peripheral portion of the external terminal plate 30 is then inserted into the gap formed between the base portion 41 and the second projection 43. As a result, the external terminal plate 30 and the insulating member 40 are integrated, improving, for example, productivity and stability.

[0042] Figures 4 to 6 show external terminal boards 30A, 30B, and 30C, which are modified versions of the external terminal board 30. For the cylindrical battery 10, it is also possible to use any of the external terminal boards 30A, 30B, or 30C instead of the external terminal board 30.

[0043] The external terminal plate 30A shown in Figure 4 is similar to the external terminal plate 30 in that it has a thick section 31A, a thin section 32A, an inclined section 33A, and an opening 34A (the same applies to external terminal plates 30B and 30C). On the other hand, in the inclined section 33A where the thickness of the external terminal plate 30A gradually decreases toward the radially outward direction, a slope is formed only on the lower surface, and the upper surface is the thick section 31 A and thin-walled portion 32 A It is flush with the top surface. In other words, the top surface of the external terminal board 30A is flat and flush across its entire surface.

[0044] The outer terminal plate 30B shown in Figure 5, like the outer terminal plate 30A, has a flat, flush upper surface. However, it differs from the outer terminal plate 30A in that a protruding portion 35B is formed on the outer periphery of the outer terminal plate 30B. The protruding portion 35B catches, for example, on the upper corner of the outer casing 16, contributing to improved stability of the outer terminal plate 30B. From the inner circumferential side of the outer terminal plate 30B, the thick portion 31B, the inclined portion 33B, the thin portion 32B, and the protruding portion 35B are arranged in this order, and all are formed in an annular shape.

[0045] The external terminal plate 30C shown in Figure 6 has a protrusion 35C formed along the outer edge of the external terminal plate 30C, similar to the external terminal plate 30B. However, it differs from the external terminal plate 30B in that the protrusion 35C also protrudes upward from the external terminal plate 30C. The upper and lower surfaces of the external terminal plate 30C are recessed by the thin-walled portion 32C. The external terminal plate 30C has a protrusion 35C that protrudes upward and downward from the outer edge of the external terminal plate 30C. C It can be said that the following is formed. From the inner circumference side of the external terminal plate 30C, the thick portion 31C, the inclined portion 33C, the thin portion 32C, and the convex portion 35C are arranged in this order, and all are formed in an annular shape.

[0046] As described above, the cylindrical battery 10 is equipped with an external terminal plate 30 having a thick-walled portion 31 and a thin-walled portion 32, and the thin-walled portion 32 is joined to the crimped portion 29 of the outer casing 16 by welding or the like. The external terminal plate 30 is preferably laser-welded to the outer casing 16, but by irradiating the thin-walled portion 32 with laser light and welding it, a good weld can be formed even if the laser output is reduced. As a result, the generation of spatter and the thermal impact on the gasket 28 are suppressed, and the good sealing performance of the sealing body 17 can be maintained.

[0047] Furthermore, the current collection terminals constituting the battery module can be welded to the thickened portion 31 of the external terminal plate 30. By providing the external terminal plate 30, the welding area for the current collection terminals can be secured without extending the crimping portion 29, and stable connection of the current collection terminals becomes possible while suppressing deformation of the sealing body 17. Since an insulating member 40 is interposed between the sealing body 17 and the external terminal plate 30, contact between the sealing body 17 and the external terminal plate 30 is more reliably prevented.

[0048] The above embodiments can be modified as appropriate without impairing the purpose of this disclosure. For example, although the above embodiments and modifications illustrate an external terminal plate formed in an annular shape in plan view, the external terminal plate may be a metal plate with an arc shape in plan view. Similarly, the planar shape of the insulating member may also be formed in an arc shape in plan view. The external terminal plate may be a metal plate having a shape other than an annular or arc shape in plan view. In this case as well, it is preferable that the external terminal plate is positioned so as not to protrude radially outward from the outer circumferential surface of the outer casing 16.

[0049] In the case of an external terminal plate that is arc-shaped in plan view, it is preferable that the length of the arc along the outer edge is 25% or more of the circumference corresponding to the arc, but it is more preferable that it is 60% or more of the circumference. In this case, it becomes easier to stably position the external terminal plate on the top surface of the case. Even in the case of an external terminal plate that is arc-shaped in plan view, a thicker portion is formed on the inner circumference side and a thinner portion on the outer circumference side, and the external terminal plate is positioned so that it does not protrude radially outward from the top surface of the case. It is also possible to use an external terminal plate that is larger than the top surface of the case and fits onto the upper end of the outer can, and to join the external terminal plate to the upper end of the side located at the opening edge of the outer can.

[0050] In the above embodiment, the example shown is one in which the sealing body 17 functions as the positive external terminal and the external terminal plate 30 functions as the negative external terminal. However, it is also possible to adopt a configuration in which the external terminal plate 30 becomes the positive external terminal and the sealing body 17 becomes the negative external terminal. [Explanation of Symbols]

[0051] 10 Cylindrical battery, 11 Positive electrode, 12 Negative electrode, 13 Separator, 14 Electrode body, 15 Case, 16 Outer can, 17 Sealing body, 18,19 Insulating plate, 20 Positive electrode lead, 21 Negative electrode lead, 22 Grooved section, 23 Internal terminal plate, 24 Lower valve body, 25 Insulating plate, 26 Upper valve body, 27 Cap, 27a Protrusion, 27b Ventilation hole, 28 Gasket, 28a Extension, 29 Crimped section, 30 External terminal plate, 31 Thick section, 32 Thin section, 33 Inclined section, 34,44 Opening, 40 Insulating member, 41 Base section, 42 First protrusion, 43 Second protrusion

Claims

1. Electrode body and A bottomed cylindrical outer can containing the electrode body, A sealing body that closes the opening of the outer can, A gasket interposed between the outer can and the sealing body, An external terminal plate joined to the outer surface of the outer casing, Equipped with, The external terminal plate is a metal plate having a thick portion and a thin portion, and an inclined portion between the thick portion and the thin portion that gradually decreases in thickness toward the radially outward direction, and the thin portion is joined to the opening edge of the outer casing, in a cylindrical battery.

2. The cylindrical battery according to claim 1, wherein the metal plate is annular or arc-shaped in plan view.

3. The cylindrical battery according to claim 2, further comprising an insulating member that is annular in plan view or arc-shaped in plan view, disposed between the sealing body and the external terminal plate.

4. The cylindrical battery according to any one of claims 1 to 3, wherein the external terminal plate is arranged so as not to protrude radially outward from the outer surface of the outer casing.

5. The gasket has an extension that extends from between the outer can and the sealing body, The cylindrical battery according to claim 3, wherein the insulating member is arranged to overlap with the extension portion.

6. An electrode body and A bottomed cylindrical outer can containing the electrode body, A sealing body that closes the opening of the outer can, A gasket interposed between the outer can and the sealing body, An external terminal plate joined to the outer surface of the outer casing, An insulating member, which is an annular or arc-shaped member in plan view, is disposed between the sealing body and the external terminal plate. Equipped with, The external terminal plate is a metal plate that is annular or arc-shaped in plan view, having a thick portion and a thin portion, wherein the thin portion is joined to the opening edge of the outer can. The gasket has an extension that extends from between the outer can and the sealing body, The insulating member is arranged to overlap with the extended portion, forming a cylindrical battery.

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