Cylindrical battery

Abstract

This cylindrical battery (10) comprises: an outer container which has the shape of a bottomed tube and accommodates an electrode body; a terminal cap (27); a plurality of cathode leads which extend out of the electrode body (14); and an upper current collector plate (50) to which the plurality of cathode leads are connected. The upper current collector plate (50) has a protruding portion (61) which protrudes towards the terminal cap (27) in the axial direction, and the terminal cap (27) has a recessed portion (71) which accommodates at least the tip of the protruding portion (61). Part of the protruding portion (61) at the tip and part of the bottom surface of the recessed portion (71) are connected by a connecting part (75). Between the protruding portion (61) and the recessed portion (71), there is a first passage portion (76) which is radially adjacent to the connecting part (75) and a second passage portion (77) which is linked to the reverse side of the first passage portion (76) from the connecting part in the radial direction and has a maximum axial length that is smaller than the maximum axial length of the first passage portion (76).

Description

Cylindrical battery

[0001] The present disclosure relates to cylindrical batteries.

[0002] A conventional cylindrical battery is described in Patent Document 1. This cylindrical battery includes an outer can, an electrode assembly housed in the outer can, two positive electrode leads extending from the positive electrode of the electrode assembly to one axial side at a distance in the winding direction, a current collector plate to which the two positive electrode leads are connected, and a terminal cap to which the current collector plate is electrically connected. This cylindrical battery collects current using the two positive electrode leads, thereby shortening the current collection path and reducing electrical resistance.

[0003] International Publication No. 2016 / 098291

[0004] Directly joining a current collector plate with multiple leads connected to it to the terminal cap can further reduce electrical resistance (note that this configuration is not publicly known or conventional). Furthermore, even if a flame occurs due to the heat generated when joining the current collector plate to the terminal cap, it is desirable to be able to extinguish the flame in a short time, as this would result in a high-quality cylindrical battery. Therefore, an object of the present disclosure is to provide a cylindrical battery that is easy to reduce electrical resistance and has high flame-extinguishing performance.

[0005] In order to solve the above problems, the cylindrical battery according to the present disclosure comprises an electrode body, a bottomed cylindrical outer can that houses the electrode body, a terminal cap having terminals exposed to the outside, a plurality of electrode leads extending from the electrode body, and a current collector plate to which the plurality of electrode leads are joined, wherein the current collector plate has a convex portion that protrudes axially toward the terminal cap, and the terminal cap has a concave portion that houses at least the tip side of the convex portion and includes a joint portion that joins a portion of the tip side of the convex portion to a portion of the bottom surface of the concave portion, and between the convex portion and the concave portion, there is a first passage portion that is radially adjacent to the joint portion, and a second passage portion that communicates with the side of the first passage portion opposite the radial joint portion side and has a maximum axial length that is smaller than the maximum axial length of the first passage portion.

[0006] The cylindrical battery according to the present disclosure can easily reduce electrical resistance and improve flame quenching performance.

[0007] Fig. 1 is an axial cross-sectional view of a cylindrical battery according to an embodiment of the present disclosure; Fig. 2 is a perspective view showing a portion of an electrode body and a positive electrode lead; Fig. 3 is a perspective view of a cylindrical battery cut along a plane including the central axis; Fig. 4 is an enlarged schematic cross-sectional view of the periphery of a protrusion in a cylindrical battery; Fig. 5 is an enlarged schematic cross-sectional view of a cylindrical battery according to a modified example, corresponding to Fig. 4; Fig. 6 is an enlarged schematic cross-sectional view of a cylindrical battery according to another modified example, corresponding to Fig. 4;

[0008] Hereinafter, an embodiment of a cylindrical battery according to the present disclosure will be described in detail with reference to the drawings. The cylindrical battery according to the present disclosure may be a primary battery or a secondary battery. It may also be a battery using an aqueous electrolyte or a battery using a non-aqueous electrolyte. Hereinafter, a non-aqueous electrolyte secondary battery (lithium ion battery) using a non-aqueous electrolyte will be exemplified as a cylindrical battery 10 according to one embodiment, but the cylindrical battery according to the present disclosure is not limited thereto.

[0009] When multiple embodiments and variations are included below, it is anticipated from the beginning that new embodiments can be constructed by appropriately combining their characteristic features. Furthermore, in the following embodiments, the same components are designated by the same reference numerals in the drawings, and redundant explanations are omitted. Furthermore, multiple drawings include schematic diagrams, and the dimensional ratios of the length, width, height, etc., of each component between different drawings do not necessarily match. Furthermore, in this specification, the sealing body 17 side in the axial direction (height direction) of the cylindrical battery 10 is referred to as "upper," and the bottom plate portion 68 side of the outer can 16 in the axial direction is referred to as "lower." Furthermore, among the components described below, components not recited in the independent claims representing the highest concepts are optional components and not required components.

[0010] 1 is an axial cross-sectional view of a cylindrical battery 10 according to one embodiment of the present disclosure. As shown in Fig. 1, the cylindrical battery 10 includes a wound electrode assembly 14, a non-aqueous electrolyte (not shown), a cylindrical outer can 16 with a bottom that houses the electrode assembly 14 and the non-aqueous electrolyte, and a sealing body 17 that closes the opening of the outer can 16.

[0011] The non-aqueous electrolyte includes a non-aqueous solvent and an electrolyte salt dissolved in the non-aqueous solvent. The non-aqueous solvent may be, for example, an ester, an ether, a nitrile, an amide, or a mixed solvent 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 of these solvents are substituted with halogen atoms such as fluorine. The non-aqueous electrolyte is not limited to a liquid electrolyte, but may also be a solid electrolyte using a gel polymer or the like. The electrolyte salt may be LiPF ６ Lithium salts such as

[0012] Fig. 2 is a perspective view showing a portion of the electrode assembly 14 and the positive electrode lead 20. As shown in Fig. 2, the electrode assembly 14 has a long positive electrode 11, a long negative electrode 12, and two long separators 13, and has a wound structure in which the positive electrode 11 and the negative electrode 12 are wound with the separator 13 interposed therebetween. A plurality of positive electrode leads are joined to the positive electrode 11 at intervals in the longitudinal direction of the positive electrode 11 and electrically connected thereto; for example, as shown in Fig. 2, eight positive electrode leads 20 are joined at approximately equal intervals in the longitudinal direction. The positive electrode leads 20 are an example of an electrode lead.

[0013] The negative electrode 12 is formed to have dimensions slightly larger than the positive electrode 11 in order to prevent lithium precipitation. That is, the negative electrode 12 is formed to be longer in the longitudinal direction and width direction (short direction) than the positive electrode 11. Furthermore, the two separators 13 are formed to have dimensions slightly larger than the positive electrode 11 and are arranged to sandwich the positive electrode 11. The separator 13 protrudes upward beyond the positive electrode 11 and the negative electrode 12, and the negative electrode 12 protrudes downward beyond the positive electrode 11 and the separator 13.

[0014] The negative electrode 12 has a negative electrode current collector exposed portion 41, where the negative electrode mixture layer 42 is not provided on the negative electrode current collector 40, at the axial lower end from the winding start end to the winding end end of the long negative electrode 12. Therefore, the axial lower end of the electrode assembly 14 is formed by the negative electrode current collector exposed portion 41. The negative electrode 12 may form the winding start end of the electrode assembly 14. However, typically, the separator 13 extends beyond the winding start end of the negative electrode 12, and the winding start end of the separator 13 becomes the winding start end of the electrode assembly 14.

[0015] The positive electrode 11 has a positive electrode current collector and a positive electrode mixture layer formed on both sides of the positive electrode current collector. The positive electrode current collector can be a metal foil, 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 layer. The positive electrode mixture layer contains a positive electrode active material, a conductive agent, and a binder. The positive electrode 11 can be produced, for example, by applying a positive electrode mixture slurry containing a positive electrode active material, a conductive agent, a binder, etc., onto the positive electrode current collector, drying the coating, and then compressing it to form a positive electrode mixture layer on both sides of the positive electrode current collector.

[0016] The positive electrode active material is mainly composed of a lithium-containing metal composite oxide. Examples of metal elements contained in the lithium-containing metal composite oxide include Ni, Co, Mn, Al, B, Mg, Ti, V, Cr, Fe, Cu, Zn, Ga, Sr, Zr, Nb, In, Sn, Ta, and W. An example of a preferred lithium-containing metal composite oxide is a composite oxide containing at least one of Ni, Co, Mn, and Al.

[0017] Examples of the conductive agent contained in the positive electrode mixture layer include carbon materials such as carbon black, acetylene black, ketjen black, and graphite. Examples of the binder contained in the positive electrode mixture layer include fluororesins such as polytetrafluoroethylene (PTFE) and polyvinylidene fluoride (PVdF), polyacrylonitrile (PAN), polyimide resins, acrylic resins, and polyolefin resins. These resins may be used in combination with cellulose derivatives such as carboxymethyl cellulose (CMC) or its salts, and polyethylene oxide (PEO).

[0018] The positive electrodes 11 are arranged at approximately equal intervals in the longitudinal direction and have the same number of positive electrode current collector exposed portions as the positive electrode leads 20. The positive electrode leads 20 are joined to the positive electrode current collector exposed portions. By joining the multiple positive electrode leads 20 at intervals in the longitudinal direction of the strip-shaped positive electrode current collector, preferably at approximately equal intervals in the longitudinal direction, the current path in the longitudinal direction of the positive electrode 11 can be shortened and the internal resistance of the cylindrical battery 10 can be reduced. The positive electrode leads 20 are covered, for example, with insulating tape (not shown), thereby suppressing short circuits between the positive electrode 11 and the negative electrode 12. It is preferable that the insulating tape cover all of the positive electrode current collector exposed portions.

[0019] As shown in FIG. 2 , the negative electrode 12 has a negative electrode current collector 40 and a negative electrode mixture layer 42 formed on both sides of the negative electrode current collector 40. The negative electrode current collector 40 can be made of a metal foil, 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 its surface. The negative electrode mixture layer 42 contains a negative electrode active material and a binder. The negative electrode 12 can be produced, for example, by applying a negative electrode mixture slurry containing the negative electrode active material and the binder to the negative electrode current collector 40, drying the coating, and then compressing it to form the negative electrode mixture layer 42 on both sides of the negative electrode current collector 40.

[0020] The negative electrode active material generally uses a carbon material that reversibly absorbs and releases lithium ions. Preferred carbon materials include natural graphite such as flake graphite, lump graphite, and amorphous graphite, and artificial graphite such as lump artificial graphite and graphitized mesophase carbon microbeads. The negative electrode mixture layer 42 may contain a silicon (Si) material as the negative electrode active material. Furthermore, the negative electrode active material may include a metal other than Si that alloys with lithium, an alloy containing such a metal, or a compound containing such a metal.

[0021] As in the case of the positive electrode 11, fluororesin, PAN, polyimide resin, acrylic resin, polyolefin resin, or the like may be used as the binder contained in the negative electrode mixture layer 42, but styrene-butadiene rubber (SBR) or a modified product thereof is preferably used. In addition to SBR or the like, the negative electrode mixture layer may also contain, for example, CMC or a salt thereof, polyacrylic acid (PAA) or a salt thereof, polyvinyl alcohol, or the like.

[0022] A porous sheet having ion permeability and insulating properties is used for the separator 13. Specific examples of the porous sheet include a microporous thin film, a woven fabric, and a nonwoven fabric. Preferred materials for the separator 13 include polyolefin resins such as polyethylene and polypropylene, and cellulose. The separator 13 may have either a single-layer structure or a laminated structure. A heat-resistant layer or the like may be formed on the surface of the separator 13.

[0023] As shown in Figure 1, the cylindrical battery 10 has an annular insulating plate 18 on the upper side of the electrode body 14. A positive electrode lead 20 attached to the positive electrode 11 passes through a through-hole in the insulating plate 18 and extends toward the sealing body 17. The sealing body 17 has an upper current collector plate 50 and a terminal cap 27. The upper current collector plate 50 is a metal annular plate member with a through-hole 50a in its radial center.

[0024] The terminal cap 27 is a metal plate-like member without a through hole, and is located axially above the sealing body 17. The axially upper end face of the terminal cap 27 is exposed to the outside except for the outer edge, and this exposed portion forms the positive electrode terminal. The sealing body 17 further includes a metal plate 51. The metal plate 51 is an annular metal member. The metal plate 51 has a through hole 51a that is a cylindrical hole.

[0025] Each positive electrode lead 20 is bent from the positive electrode 11 through the through hole 50a of the upper current collector plate 50 so as to fit along the upper surface of the upper current collector plate 50. The tip of each positive electrode lead 20 is sandwiched between the upper surface of the upper current collector plate 50 and the lower surface of the metal plate 51. Each positive electrode lead 20 is joined to the upper surface of the upper current collector plate 50. The upper current collector plate 50 and the metal plate 51 are also joined, and each positive electrode lead 20 and the metal plate 51 are also joined. These joints can be achieved, for example, by laser welding the tip of each positive electrode lead 20 sandwiched between the upper current collector plate 50 and the metal plate 51 by irradiating a laser beam from the side opposite the upper current collector plate 50 in the thickness direction of the metal plate 51. By laser welding the tip of the positive electrode lead 20 sandwiched between the upper current collector plate 50 and the metal plate 51, the positive electrode lead 20 can be reliably and easily welded and joined to the upper current collector plate 50. The upper current collector plate 50 does not have to be joined to the metal plate 51, and the positive electrode lead 20 does not have to be joined to the metal plate 51. Furthermore, the cylindrical battery does not have to have a metal plate.

[0026] The upper current collecting plate 50 has a first annular portion 60 located radially outward and extending radially, an annular protrusion 61 connected to a radially inner end of the first annular portion 60 and protruding axially upward beyond that end, and a second annular portion 63 connected to the annular protrusion 61 via an annular step 62 extending downward from the annular protrusion 61 and extending radially inward from the step 62. The terminal cap 27 also has an annular recess 71 that accommodates at least the tip side of the annular protrusion 61.

[0027] The cylindrical battery 10 includes a metal lower current collector plate 52 axially below the electrode assembly 14. Referring to FIGS. 1 and 2 , the electrode assembly 14 is pressed against the upper surface of the lower current collector plate 52 so as to tilt the strip-shaped negative electrode current collector exposed portion 41 radially inward. Laser light is irradiated from the underside of the lower current collector plate 52, thereby laser-welding and joining the negative electrode current collector exposed portion 41 over a wide area to the upper surface of the lower current collector plate 52. Laser light is also irradiated from the underside of the outer can 16, thereby laser-welding the bottom plate portion 68 of the outer can 16 to the lower current collector plate 52. This electrically connects the negative electrode 12 of the electrode assembly 14 to the outer can 16 via the lower current collector plate 52. By joining the negative electrode current collector exposed portion 41 over a wide area to the upper surface of the lower current collector plate 52, it is possible to prevent current from flowing long distances along the longitudinal direction of the elongated negative electrode 12, thereby reducing the electrical resistance of the cylindrical battery 10.

[0028] The outer can 16 has an annular groove 35 in a portion of the axial direction of its cylindrical outer circumferential surface. The groove 35 can be formed, for example, by spinning a portion of the cylindrical outer circumferential surface radially inward to create a recess radially inward. The sealing body 17 is placed on the groove 35 and is fixed to the opening of the outer can 16 by crimping via a gasket 28.

[0029] The internal space of the cylindrical battery 10 is sealed by sealing the space between the outer can 16 and the sealing body 17 with an annular gasket 28. The gasket 28 is sandwiched between the outer can 16 and the sealing body 17, insulating the sealing body 17 from the outer can 16. In other words, the gasket 28 serves as a sealant to maintain airtightness inside the battery and as an insulator to insulate the outer can 16 from the sealing body 17. The gasket 28 may have a through hole 28a. The local strength (elastic force) of the gasket 28 can be adjusted by adjusting the size and shape of the through hole 28a provided in the gasket 28.

[0030] The cylindrical battery 10 has a thin-walled portion 69 on the bottom plate portion 68 of the outer can 16. The thin-walled portion 69 can be formed by providing a circular, C-shaped, or other marking on the bottom plate portion 68. By providing the thin-walled portion 69 on the bottom plate portion 68, the bottom plate portion 68 can be smoothly broken starting from the thin-walled portion 69 when the cylindrical battery 10 generates abnormal heat. Therefore, when the cylindrical battery 10 generates abnormal heat, high-temperature gas inside the battery can be smoothly released to the outside, improving the safety of the cylindrical battery 10.

[0031] The exposed negative electrode current collector portion 41 of the electrode body 14 is joined to the lower current collector plate 52, and the positive electrode lead 20 extending from the electrode body 14 is joined to the upper current collector plate 50. Thereafter, an insulating plate 18 is placed between the electrode body 14 and the upper current collector plate 50. Next, the assembly including the electrode body 14, upper current collector plate 50, and lower current collector plate 52 is inserted into the outer can 16 before crimping from the side of the lower current collector plate 52. At this time, a part of the gasket 28 is positioned between the outer can 16 and the sealing body 17.

[0032] Thereafter, an electrolyte is poured into the outer can 16 before crimping, and then the terminal cap 27 is placed on the upper current collector plate 50 so that the tip side of the protrusion 61 of the upper current collector plate 50 is accommodated in the recess 71. The above crimping is then performed to seal the opening of the outer can 16. Finally, to improve electrical conductivity, a laser beam is irradiated from the outside in the axial direction of the terminal cap 27 to laser weld the terminal cap 27 and the upper current collector plate 50 together.

[0033] 3, which is a perspective view of cylindrical battery 10 cut along a plane including the central axis, laser light is applied in a circular pattern from the axially outer side of terminal cap 27 to a radial position corresponding to the radial center of annular recess 71, and the radial center of recess 71 is laser-welded to the radial center of the tip surface of protrusion 61. This laser welding ensures good electrical conductivity between terminal cap 27 and upper current collecting plate 50.

[0034] By fitting at least the tip of the protrusion 61 on the upper current collector plate 50 into the recess 71 of the terminal cap 27, the upper current collector plate 50 and the terminal cap 27 can be more easily brought into close contact with each other, thereby enabling the upper current collector plate 50 and the terminal cap 27 to be reliably joined by laser welding. Furthermore, by fitting at least the tip of the protrusion 61 into the recess 71, a labyrinth structure can be formed between the protrusion 61 and the recess 71, making it difficult for the electrolyte to penetrate between the protrusion 61 and the recess 71. This prevents deterioration of the cylindrical battery 10 due to electrolyte penetrating between the protrusion 61 and the recess 71. Furthermore, because hydrocarbons generated by the evaporation of the electrolyte are less likely to penetrate between the protrusion 61 and the recess 71, the combustion of hydrocarbons and the generation of flames during laser welding can be prevented, resulting in the production of a high-quality cylindrical battery 10.

[0035] In the cylindrical battery 10, the terminal cap 27 electrically connected to the multiple positive electrode leads 20 serves as the positive electrode terminal, and the outer casing 16 electrically connected to the negative electrode current collector exposed portion 41 serves as the negative electrode terminal. Note that because the upper current collector plate 50 has an annular step portion 62 extending axially downward from the protrusion 61, an axial gap can be provided between the second annular portion 63 and the terminal cap 27. Therefore, the positive electrode lead 20 and the metal plate 51 can be disposed in this axial gap.

[0036] Next, a detailed structure of the area around the protrusion 61 of the cylindrical battery 10 will be described. Figure 4 is an enlarged schematic cross-sectional view of the area around the protrusion 61 of the cylindrical battery 10. Note that in Figure 4 and Figures 5 and 6 used below, for ease of understanding, the axial length of the gap between the protrusion 61 of the upper current collector plate 50 and the recess 71 of the terminal cap 27 is exaggerated, and the shape characteristics of the gap are also exaggerated.

[0037] As shown in FIG. 4 , the cylindrical battery 10 has a joint 75 that joins a portion of the tip of the protrusion 61 to a portion of the bottom of the recess 71. The cylindrical battery 10 also has a first passage portion 76 between the protrusion 61 and the recess 71 that is radially adjacent to the joint 75, and a second passage portion 77 that communicates with the radially opposite side of the first passage portion 76 from the joint 75 and has a maximum axial length shorter than the maximum axial length of the first passage portion 76. With this configuration, the cylindrical battery 10 has the first passage portion 76 and the second passage portion 77 between the protrusion 61 and the recess 71. The first passage portion 76 is radially adjacent to the joint 75. The second passage portion 77 communicates with the first passage portion 76 on the opposite side of the first passage portion 76 from the joint 75. The length of the portion of the second passage portion 77 that has the longest axial length is shorter than the length of the portion of the first passage portion 76 that has the longest axial length.

[0038] As shown in FIG. 4 , in a cross section including the axial direction of the cylindrical battery 10, the first passage portion 76 and the second passage portion 77 are located on both radial sides of the joint portion 75. In the example shown in FIG. 4 , the joint portion 75, the first passage portion 76, and the second passage portion 77 extend in a circular shape when viewed in the radial direction of the cylindrical battery 10. As shown in FIG. 4 , in a cross section including the axial direction of the cylindrical battery 10, the second passage portion 77 includes a passage portion 81 surrounded by a zigzag first line 78 with repeated concave and convex portions and a zigzag second line 79 with repeated concave and convex portions. The convex portions of the first line 78 face the concave portions of the second line 79 in the axial direction, and the concave portions of the first line 78 face the convex portions of the second line 79 in the axial direction. Therefore, the passage portion 81 is a zigzag passage portion that progresses in a zigzag pattern.

[0039] In other words, each of terminal cap 27 and upper current collecting plate 50 has an uneven surface with repeated concave and convex portions in the radial direction. The uneven surface of terminal cap 27 fits into the uneven surface of upper current collecting plate 50, and faces the uneven surface of upper current collecting plate 50 in the axial direction so that a zigzag passage portion 81 is formed between the two uneven surfaces. The uneven surfaces of terminal cap 27 and upper current collecting plate 50 can be formed by, for example, pressing, polishing, or the like.

[0040] In this embodiment, a zigzag passage portion 81 is formed over the entire radial extent of the second passage portion 77, and the second passage portion 77 coincides with the zigzag passage portion 81. However, the zigzag passage portion may be provided only in a portion of the radial extent of the second passage portion. Furthermore, while the configuration in which the joint portion 75, first passage portion 76, and second passage portion 77 extend in a circular shape when viewed in the radial direction of the cylindrical battery 10 has been described as an example, the joint portion 75 does not necessarily have to be formed in a circular shape. For example, a configuration in which multiple joint portions are formed in an arc shape may also be used. In a configuration with multiple joint portions, first and second passage portions are provided corresponding to each of the multiple joints.

[0041] As described above, after the electrolyte is poured, laser welding is performed to join the terminal cap 27 and the upper current collecting plate 50, which creates a risk of fire when the area where the electrolyte is present is irradiated with laser light. In this case, in the case of a fire caused by a heat source, if the temperature of the wall near the fire area is low, the heat of the flame is absorbed by the wall, causing a flame-extinction phenomenon in which the combustion does not continue.

[0042] In this context, according to this embodiment, a cylindrical battery 10 includes a bottomed tubular outer can 16 that houses an electrode assembly 14, a terminal cap 27, multiple positive electrode leads 20 extending from the electrode assembly 14, and an upper current collector plate 50 to which the multiple positive electrode leads 20 are joined. The upper current collector plate 50 has a protrusion 61 that protrudes axially toward the terminal cap 27, and the terminal cap 27 has a recess 71 that houses at least the tip end of the protrusion 61. A portion of the tip end of the protrusion 61 is joined to a portion of the bottom surface of the recess 71 by a joint 75. Between the protrusion 61 and the recess 71, there are a first passage portion 76 that is radially adjacent to the joint 75, and a second passage portion 77 that communicates with the side of the first passage portion 76 opposite the radial joint and has a maximum axial length that is shorter than the maximum axial length of the first passage portion 76.

[0043] Therefore, the second passage portion 77, which has a maximum axial length smaller than the maximum axial length of the first passage portion 76, is located on the opposite side of the first passage portion 76 from the radial joint portion 75, so heat can be efficiently absorbed by the axially opposing surfaces on both axial sides of the second passage portion 77, which has a narrow axial length.

[0044] Furthermore, the axial thickness of the terminal cap 27 and upper current collector plate 50 portions that axially overlap the second passage portion 77 can be increased, thereby increasing the thermal capacity of these portions and the amount of heat they can absorb. Therefore, for this reason as well, flame quenching can be effectively achieved, and even if a flame occurs during laser welding, the flame can be extinguished in a short time, resulting in a high-quality cylindrical battery 10.

[0045] Furthermore, the first passage portion 76 and the second passage portion 77 are present on both radial sides of the joint portion 75. Therefore, the radial extent of the second passage portion 77 can be increased, and the flame quenching phenomenon can be more effectively generated.

[0046] Furthermore, the second passage portion 77 includes a passage portion 81 that progresses in a zigzag pattern and is surrounded by a first zigzag line 78 with repeated concaves and convexes and a second zigzag line 79 with repeated convexities and convexes. This makes it possible to increase the path length of the zigzag passage portion 81 and increase the surface area of ​​the passage portion 81. This allows the zigzag passage portion 81 to absorb heat more effectively, thereby more effectively generating a flame-extinguishing effect.

[0047] In the production of metal parts, the polishing marks of the mold or rolling rollers may be transferred to the material, resulting in unevenness on the surface of the metal part. However, in the technology disclosed herein, it is necessary for the surfaces of the positive electrode cap and the upper current collector plate to approach each other in the axial direction so that the approaching surfaces can exist over a wider area. Therefore, it is preferable that the axial length of the convex portions of the zigzag-progressing passage portion 81 be longer than the axial length of the convex portions of the unevenness due to the polishing marks of the mold or rolling rollers. For example, it is preferable that the axial length of the convex portions of the passage portion 81 be 0.05 mm to 1.5 mm, and it is even more preferable that the axial length of the convex portions of the passage portion 81 be 0.1 mm to 1.0 mm.

[0048] [Test to Confirm Anti-Flame Effect] The cylindrical batteries of the comparative example and the cylindrical batteries of Examples 1-4 were checked for anti-flame effect.

[0049] <Cylindrical Battery of Comparative Example> In comparison with the cylindrical battery 10 of the above embodiment in which the terminal cap 27 and the upper current collector plate 50 were joined by the above-described laser welding, a cylindrical battery was fabricated that had only the first passage portion 76 and no second passage portion 77. More specifically, in comparison with the cylindrical battery 10 of the above embodiment, a cylindrical battery was fabricated in which an extension of the first passage portion 76 was present at the radial position of the second passage portion 77. The axial length of the first passage portion 76 was set to 2 mm.

[0050] <Cylindrical Battery of Example 1> A cylindrical battery 10 according to the above embodiment was produced. The terminal cap 27 and the upper current collector plate 50 were joined by laser welding as described above. The axial length of the zigzag second passage portion 77 was set to 0.1 mm.

[0051] <Cylindrical Battery of Example 2> A cylindrical battery 10 according to the above embodiment was produced. The terminal cap 27 and the upper current collector plate 50 were joined by laser welding as described above. The axial length of the zigzag second passage portion 77 was set to 0.5 mm.

[0052] <Cylindrical Battery of Example 3> A cylindrical battery 10 according to the above embodiment was produced. The terminal cap 27 and the upper current collector plate 50 were joined by laser welding as described above. The axial length of the zigzag second passage portion 77 was set to 1.0 mm.

[0053] <Cylindrical Battery of Example 4> A cylindrical battery 10 according to the above embodiment was produced. The terminal cap 27 and the upper current collector plate 50 were joined by the above-described laser welding. The axial length of the zigzag second passage portion 77 was set to 1.5 mm.

[0054] [Method for checking flame-extinguishing effect] We checked whether there were any signs of combustion. Specifically, we checked whether there were any discolored areas around the welds formed by laser welding. We also measured the amount of moisture inside each cylindrical battery. When hydrocarbons produced by vaporizing the electrolyte are burned, water is produced. Therefore, by measuring the amount of moisture, we can determine whether combustion has occurred.

[0055] [Test Results] The test results are shown in Table 1.

[0056] As shown in Table 1, no traces of combustion were observed in any of the cylindrical batteries (cylindrical batteries of Examples 1-4) that had the zigzag-progressing second passage portion 77. That is, it was confirmed that in the cylindrical batteries of Examples 1-4, either no combustion occurred or, if a flame occurred, it was extinguished in a short time. As described above, the provision of a second passage portion can improve the flame-extinguishing effect regardless of the maximum axial length of the second passage portion. Furthermore, a maximum axial length of the second passage portion of 0.1 mm or more is preferable because heat can be effectively absorbed by the inner surface of the second passage portion. Furthermore, a maximum axial length of the second passage portion of 1 mm or less is preferable because the flame-extinguishing phenomenon can be effectively generated. Furthermore, a radial dimension of the range in which the second passage portion exists of 0.2 mm or more is preferable because the contact area of ​​the portion that can effectively absorb heat can be increased, thereby enhancing the flame-extinguishing effect. Furthermore, a radial dimension of the range in which the second passage portion exists of 1 mm or less is preferable because it facilitates the fabrication of a compact cylindrical battery with a small radial dimension.

[0057] The present disclosure is not limited to the above-described embodiment and its modifications, and various improvements and modifications are possible within the scope of the claims of the present application and their equivalents.

[0058] For example, in the above embodiment, the second passage section 77 includes a zigzag passage portion 81. However, the second passage section does not have to include a zigzag passage portion. Specifically, as shown in Figure 5, which is an enlarged schematic cross-sectional view of a modified cylindrical battery 110 corresponding to Figure 4, the second passage section 177 may have a linear shape in a cross section including the axial direction of the cylindrical battery 110.

[0059] Even if the second passage portion 177 does not include a zigzag passage portion like the cylindrical battery 110, narrowing the axial length of the second passage portion 177 allows the inner surface of the second passage portion 177 to effectively absorb heat and enhance the flame-extinguishing effect. Furthermore, the thickness of the portion of the terminal cap 127 that axially overlaps the second passage portion 177 and the thickness of the portion of the upper current collecting plate 150 that axially overlaps the second passage portion 177 can be increased, thereby increasing the heat capacity of the overlapping portions. This also contributes to an enhanced flame-extinguishing effect.

[0060] In cylindrical battery 110, the portion of terminal cap 127 that axially overlaps second passage portion 177 has protrusion 127a that protrudes axially downward. Also, the portion of upper current collector plate 150 that axially overlaps second passage portion 177 has protrusion 150a that protrudes axially upward. When the axial length of first passage portion 176 is t1, the axial thickness of protrusion 127a is t2, and the axial thickness of protrusion 150a is t3, then t1 > (t2 + t3) holds.

[0061] However, when forming the second passage portion, a protrusion may be provided on only one of the portion of the terminal cap that axially overlaps the second passage portion and the portion of the upper current collector plate that axially overlaps the second passage portion. For example, as shown in Figure 6, which is an enlarged schematic cross-sectional view of another modified cylindrical battery 210 corresponding to Figure 4, a protrusion 227a that protrudes axially downward may be provided on the portion of the terminal cap 227 that axially overlaps the second passage portion 277, while a protrusion that protrudes axially upward may not be provided on the portion of the upper current collector plate 250 that axially overlaps the second passage portion 277. This configuration also achieves good flame quenching performance.

[0062] In addition, the case where the first passage portion 76 and the second passage portion 77 are present on both radial sides of the joint portion 75 formed by laser welding has been described. However, the first passage portion and the second passage portion may be present on only one radial side of the joint portion formed by laser welding. Also, the case where the cylindrical battery 10 includes only one annular insulating plate 18 above the electrode assembly 14 has been described. However, the cylindrical battery may include another insulating plate between the annular insulating plate and the electrode assembly, or may include two insulating plates arranged double above the electrode assembly.

[0063] In addition, we have described a case in which the electrical resistance of the cylindrical battery 10 is reduced by joining the negative electrode current collector exposed portion 41 to the lower current collector plate 52 and joining the lower current collector plate 52 to the bottom plate portion 68 of the outer can 16. However, joining the negative electrode current collector exposed portion 41 to the lower current collector plate 52 is not necessarily required. For example, a negative electrode lead extending from a radially inner portion of the negative electrode current collector exposed portion may be joined to the bottom of the can, and the outer circumferential surface of the electrode assembly may be formed of a negative electrode current collector without a negative electrode mixture layer, so that the negative electrode current collector constituting the outer circumferential surface of the electrode assembly contacts the cylindrical inner circumferential surface of the outer can. This also reduces the electrical resistance of the cylindrical battery. We have described a case in which the terminal cap 27 constitutes the positive electrode and the outer can 16 constitutes the negative electrode. However, the polarity may be reversed, with the terminal cap constituting the negative electrode and the outer can constituting the positive electrode.

[0064] REFERENCE SIGNS LIST 10,110,210 Cylindrical battery, 11 Positive electrode, 12 Negative electrode, 13 Separator, 14 Electrode body, 16 Outer can, 17 Sealing body, 18 Insulating plate, 20 Positive electrode lead, 27,127,227 Terminal cap, 28 Gasket, 40 Negative electrode current collector, 41 Negative electrode current collector exposed portion, 42 Negative electrode mixture layer, 50,150,250 Upper current collector plate, 51 Metal plate, 52 Lower current collector plate, 60 First annular portion, 61 Convex portion, 62 Step portion, 63 Second annular portion, 68 Bottom plate portion, 69 Thin portion, 71 Recessed portion, 75 Joint portion, 76,176 First passage portion, 77, 177, 277 Second passage portion, 78 First line, 79 Second line, 81 Zigzag passage portion, 127a, 227a Protrusion of terminal cap, 150a Protrusion of upper current collecting plate.

Claims

1. An electrode body; a cylindrical exterior can containing the electrode assembly; a terminal cap having a terminal exposed to the outside; A plurality of electrode leads extending from the electrode body; a current collector plate to which the plurality of electrode leads are joined, the current collector plate has a protrusion protruding toward the terminal cap in the axial direction, and the terminal cap has a recess for accommodating at least a tip side of the protrusion, a joining portion joining a part of a tip side of the protrusion and a part of a bottom surface of the recess, a first passage portion between the convex portion and the concave portion, the first passage portion being radially adjacent to the joint portion, and a second passage portion communicating with the side of the first passage portion opposite the joint portion in the radial direction and having a maximum axial length smaller than the maximum axial length of the first passage portion.

2. The cylindrical battery according to claim 1 , wherein the first passage portion and the second passage portion are present on both radial sides of the joint portion.

3. The cylindrical battery according to claim 1 , wherein the second passage portion has a linear shape in a cross section including the axial direction.

4. In a cross section including the axial direction, the second passage portion includes a passage portion surrounded by a first line having a zigzag pattern with repeated concaves and convexes and a second line having a zigzag pattern with repeated concaves and convexes, The cylindrical battery according to claim 1 , wherein the convex portion of the first line faces the concave portion of the second line in the axial direction, and the concave portion of the first line faces the convex portion of the second line in the axial direction.