Cylindrical battery

Abstract

A cylindrical battery (10) is provided with: a bottomed cylindrical outer can housing an electrode body; a terminal cover (27); a plurality of positive electrode leads extending from the electrode body (14); and an upper collector plate (50) to which a plurality of positive electrode leads are joined. The upper collector plate (50) has a convex portion (61) protruding toward the terminal cover (27) side in the axial direction, and the terminal cover (27) has a concave portion (71) that accommodates at least the tip side of the convex portion (61). A part of the front end side of the convex part (61) and a part of the bottom surface of the concave part (71) are joined at a joining part (75). Between the convex portion (61) and the concave portion (71): a first passage portion (76) adjacent to the joining portion (75) in the radial direction; and a second passage section (77) that communicates with the opposite side of the first passage section (76) from the joining section side in the radial direction, and that has an axial maximum length that is smaller than the axial maximum length of the first passage section (76).

Description

Technical Field

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

[0002] Conventionally, as a cylindrical battery, there is a battery described in Patent Document 1. The cylindrical battery includes an outer can, an electrode body housed in the outer can, two positive electrode leads extending from the positive electrode of the electrode body to one side in the axial direction with a gap in the winding direction, a current collector connecting the two positive electrode leads, and a terminal cover electrically connected to the current collector. The cylindrical battery uses two positive electrode leads for current collection, so the current collection path can be shortened and the resistance can be reduced.

[0003] Prior Art Literature

[0004] Patent Document 1: International Publication No. 2016 / 098291 Summary of the invention

[0005] If the collector plate connected to the plurality of leads is directly joined to the terminal cover, the resistance can be further reduced (this technical configuration is not known and is not a prior art). In addition, even if a flame is generated due to the heat when the collector plate is joined to the terminal cover, if the flame can be extinguished in a short time, the cylindrical battery can be made into a high-quality battery, which is preferred. Therefore, the purpose of the present disclosure is to provide a cylindrical battery that is easy to reduce resistance and has high fire extinguishing performance.

[0006] In order to solve the above-mentioned problems, the cylindrical battery involved in the present disclosure comprises an electrode body, a bottomed cylindrical outer can for accommodating the electrode body, a terminal cover with terminals exposed to the outside, a plurality of electrode leads extending from the electrode body, and a collector plate to which the plurality of electrode leads are joined, the collector plate having a convex portion protruding toward the axial terminal cover side, and the terminal cover having a concave portion for accommodating at least the front end side of the convex portion, the cylindrical battery including a joint portion for joining a portion of the front end side of the convex portion with a portion of the bottom surface of the concave portion, a first passage portion and a second passage portion between the convex portion and the concave portion, the first passage portion and the joint portion being radially adjacent to each other, the second passage portion being connected to the opposite side of the radial joint portion side of the first passage portion, and having an axial maximum length that is smaller than the axial maximum length of the first passage portion.

[0007] According to the cylindrical battery according to the present disclosure, the resistance can be easily reduced and the fire extinguishing performance can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 This is a cross-sectional view in the axial direction of a cylindrical battery according to one embodiment of the present disclosure.

[0009] Figure 2 It is a perspective view showing a part of the electrode body and the positive electrode lead.

[0010] Figure 3 This is a perspective view of a cylindrical battery in a state cut along a plane including the central axis.

[0011] Figure 4 This is an enlarged schematic cross-sectional view of the periphery of a convex portion in a cylindrical battery.

[0012] Figure 5 A cylindrical battery of a modified example Figure 4 Corresponding enlarged schematic cross-sectional view.

[0013] Figure 6 Another modification of a cylindrical battery Figure 4 Corresponding enlarged schematic cross-sectional view. DETAILED DESCRIPTION

[0014] Hereinafter, the embodiment of the cylindrical battery involved in the present disclosure will be described in detail with reference to the accompanying drawings. In addition, the cylindrical battery of the present disclosure may be a primary battery or a secondary battery. In addition, it may be a battery using an aqueous electrolyte or a battery using a non-aqueous electrolyte. Hereinafter, as a cylindrical battery 10 of one embodiment, a non-aqueous electrolyte secondary battery (lithium ion battery) using a non-aqueous electrolyte is exemplified, but the cylindrical battery of the present disclosure is not limited thereto.

[0015] In the case where the following includes multiple embodiments or variations, it is envisaged from the beginning that these characteristic parts are appropriately combined to construct a new embodiment. In addition, in the following embodiments, the same structure is marked with the same symbol in the drawings, and repeated descriptions are omitted. In addition, multiple drawings include schematic diagrams, and the dimension ratios of the vertical, horizontal, height, etc. of each component may not be consistent between different figures. In addition, in this specification, the axial (height direction) side of the sealing body 17 of the cylindrical battery 10 is set to "upper", and the axial side of the bottom plate portion 68 of the outer can 16 is set to "lower". In addition, among the constituent elements described below, the constituent elements that are not recorded in the independent claims representing the highest concept are arbitrary constituent elements and are not essential constituent elements.

[0016] Figure 1 FIG. 1 is a cross-sectional view of a cylindrical battery 10 in the axial direction according to an embodiment of the present disclosure. Figure 1 As shown, the cylindrical battery 10 includes a wound electrode body 14 , a nonaqueous electrolyte (not shown), a bottomed cylindrical outer can 16 accommodating the electrode body 14 and the nonaqueous electrolyte, and a sealing body 17 that closes the opening of the outer can 16 .

[0017] The non-aqueous electrolyte comprises a non-aqueous solvent and an electrolyte salt dissolved in the non-aqueous solvent. The non-aqueous solvent may be, for example, esters, ethers, nitriles, amides, and mixed solvents of two or more thereof. The non-aqueous solvent may contain a halogen substitution body in which at least a portion of the hydrogen atoms of these solvents are replaced with halogen atoms such as fluorine. In addition, the non-aqueous electrolyte is not limited to a liquid electrolyte, and may also be a solid electrolyte using a gel-like polymer or the like. The electrolyte salt uses a lithium salt such as LiPF6.

[0018] Figure 2 2 is a perspective view showing a portion of the electrode body 14 and the positive electrode lead 20. Figure 2 As shown, the electrode body 14 includes a long positive electrode 11, a long negative electrode 12, and two long separators 13, and has a winding 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, for example Figure 2 As shown, eight positive electrode leads 20 are joined at substantially equal intervals in the longitudinal direction. The positive electrode lead 20 is an example of an electrode lead.

[0019] In order to prevent lithium precipitation, the negative electrode 12 is formed to be one size larger than the positive electrode 11. That is, the negative electrode 12 is formed to be longer than the positive electrode 11 in the length direction and the width direction (short side direction). In addition, the two separators 13 are formed to be one size larger than the positive electrode 11 and are arranged to sandwich the positive electrode 11. The separator 13 protrudes upward more than the positive electrode 11 and the negative electrode 12, and the negative electrode 12 protrudes downward more than the positive electrode 11 and the separator 13.

[0020] The negative electrode 12 has a negative electrode collector exposed portion 41 in which no negative electrode mixture layer 42 is provided in the negative electrode collector 40 at the lower end in the axial direction from the end on the winding start side to the end on the winding end side in the longitudinal direction of the long strip of the negative electrode 12. Therefore, the lower end in the axial direction of the electrode body 14 is constituted by the negative electrode collector exposed portion 41. The negative electrode 12 may also constitute the winding start end of the electrode body 14. However, generally speaking, the separator 13 extends beyond the winding start side end of the negative electrode 12, and the winding start side end of the separator 13 becomes the winding start end of the electrode body 14.

[0021] 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 use a metal foil such as aluminum or aluminum alloy that is stable within the potential range of the positive electrode 11, a thin film having the metal on the surface, etc. In addition, the positive electrode mixture layer contains a positive electrode active material, a conductive agent, and a binder. The positive electrode 11 can be made, for example, as follows: a positive electrode mixture slurry containing a positive electrode active material, a conductive agent, and a binder is applied to the positive electrode current collector, and after the coating is dried, it is compressed to form a positive electrode mixture layer on both sides of the positive electrode current collector.

[0022] The positive electrode active material is composed of a lithium-containing metal composite oxide as a main component. As the metal elements contained in the lithium-containing metal composite oxide, Ni, Co, Mn, Al, B, Mg, Ti, V, Cr, Fe, Cu, Zn, Ga, Sr, Zr, Nb, In, Sn, Ta, W, etc. can be cited. An example of a preferred lithium-containing metal composite oxide is a composite oxide containing at least one of Ni, Co, Mn, and Al.

[0023] As the conductive agent contained in the positive electrode mixture layer, carbon materials such as carbon black, acetylene black, Ketjen black, and graphite can be exemplified. As the binder contained in the positive electrode mixture layer, fluororesins such as polytetrafluoroethylene (PTFE) and polyvinylidene fluoride (PVdF), polyacrylonitrile (PAN), polyimide resins, acrylic resins, polyolefin resins, etc. can be exemplified. These resins can be used in combination with cellulose derivatives such as carboxymethyl cellulose (CMC) or its salts, polyethylene oxide (PEO), etc.

[0024] The positive electrode 11 has exposed portions of the positive electrode current collector which are arranged at approximately equal intervals in the longitudinal direction thereof and have the same number as the positive electrode leads 20. The positive electrode lead 20 is joined to the exposed portion of the positive electrode current collector. By joining a plurality of 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 lead 20 is covered, for example, with an insulating tape (not shown), and as a result, a short circuit between the positive electrode 11 and the negative electrode 12 is suppressed. The insulating tape preferably covers the entire exposed portion of the positive electrode current collector.

[0025] like Figure 2 As shown, the negative electrode 12 has a negative electrode collector 40 and a negative electrode mixture layer 42 formed on both sides of the negative electrode collector 40. The negative electrode collector 40 can use a metal foil such as copper or copper alloy that is stable within the potential range of the negative electrode 12, a thin film having the metal on the surface, etc. The negative electrode mixture layer 42 contains a negative electrode active material and a binder. The negative electrode 12 can be made, for example, as follows: a negative electrode mixture slurry containing a negative electrode active material and a binder is applied to the negative electrode collector 40, and after the coating is dried, it is compressed to form a negative electrode mixture layer 42 on both sides of the negative electrode collector 40.

[0026] The negative electrode active material generally uses a carbon material that reversibly absorbs and releases lithium ions. Preferred carbon materials are natural graphites such as flaky graphite, blocky graphite, and earthy graphite, blocky artificial graphite, and artificial graphites such as graphitized mesophase carbon microbeads. In the negative electrode mixture layer 42, as the negative electrode active material, a Si material containing silicon (Si) may be included. In addition, the negative electrode active material may also use a metal other than Si that is alloyed with lithium, an alloy containing the metal, a compound containing the metal, and the like.

[0027] The binder contained in the negative electrode mixture layer 42 is the same as that in the positive electrode 11, and fluororesin, PAN, polyimide resin, acrylic resin, polyolefin resin, etc. can be used, preferably styrene-butadiene rubber (SBR) or its modified body. In the negative electrode mixture layer, for example, in addition to SBR, CMC or its salt, polyacrylic acid (PAA) or its salt, polyvinyl alcohol, etc. can also be contained.

[0028] The separator 13 may be a porous sheet having ion permeability and insulation. Specific examples of the porous sheet include microporous films, woven fabrics, nonwoven fabrics, etc. The material of the separator 13 is preferably a polyolefin resin such as polyethylene and polypropylene, cellulose, etc. The separator 13 may be a single-layer structure or a laminated structure. A heat-resistant layer may be formed on the surface of the separator 13.

[0029] like Figure 1 As shown, the cylindrical battery 10 is provided with an annular insulating plate 18 on the upper side of the electrode body 14. The positive electrode lead 20 attached to the positive electrode 11 extends toward the sealing body 17 through the through hole of the insulating plate 18. The sealing body 17 has an upper collector plate 50 and a terminal cover 27. The upper collector plate 50 is a metal annular plate member having a through hole 50a in the radial center.

[0030] The terminal cover 27 is a metal plate-shaped member having no through-hole, and is located on the axial upper side of the sealing body 17. The end surface of the axial upper side of the terminal cover 27 is exposed to the outside except for the outer edge, and the exposed portion constitutes the positive terminal. The sealing body 17 also has a metal plate 51. The metal plate 51 is a metal annular member. The metal plate 51 has a through hole 51a formed by a cylindrical hole.

[0031] Each positive lead 20 is bent from the positive electrode 11 through the through hole 50a of the upper current collector plate 50 so as to follow the upper surface of the upper current collector plate 50. The front end portion of each positive 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 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 lead 20 and the metal plate 51 are also joined. These joinings can be achieved, for example, by irradiating a laser from the opposite side of the upper current collector plate 50 side in the thickness direction of the metal plate 51 to perform laser welding in a state where the front end portion of each positive lead 20 is sandwiched between the upper current collector plate 50 and the metal plate 51. By performing laser welding in a state where the front end of the positive lead 20 is sandwiched between the upper current collector plate 50 and the metal plate 51, the positive lead 20 can be reliably and easily welded to the upper current collector plate 50 and joined. In addition, the upper current collector plate 50 may not be joined to the metal plate 51, and the positive lead 20 may not be joined to the metal plate 51. In addition, the cylindrical battery may not have a metal plate.

[0032] The upper current collector plate 50 includes a first annular portion 60 located radially outward and extending in the radial direction, an annular protrusion 61 connected to the radially inner end of the first annular portion 60 and protruding axially upward from the end, and a second annular portion 63 connected to the annular protrusion 61 via an annular step portion 62 extending downward from the annular protrusion 61 and extending radially inward from the step portion 62. In addition, the terminal cover 27 includes an annular recess 71 that accommodates at least the front end side of the annular protrusion 61.

[0033] The cylindrical battery 10 includes a metal lower current collector plate 52 on the axially lower side of the electrode body 14. Figure 1 and Figure 2 , by irradiating laser from the lower surface side of the lower current collector 52 while pressing the electrode body 14 on the upper surface of the lower current collector 52 in such a manner that the strip-shaped negative current collector exposed portion 41 is turned inward in the radial direction, the negative current collector exposed portion 41 is widely laser welded and joined to the upper surface of the lower current collector 52. In addition, by irradiating laser from the lower side of the outer can 16, the bottom plate portion 68 of the outer can 16 is joined to the lower current collector 52 by laser welding. Thus, the negative electrode 12 of the electrode body 14 is electrically connected to the outer can 16 via the lower current collector 52. By widely joining the negative current collector exposed portion 41 to the upper surface of the lower current collector 52, it is possible to suppress the current from flowing over a long distance along the length direction of the long strip-shaped negative electrode 12, and the resistance of the cylindrical battery 10 can be reduced.

[0034] The outer can 16 has an annular groove 35 on a portion of the axial direction of the outer circumferential surface of the cylinder. The groove 35 can be formed, for example, by spinning a portion of the outer circumferential surface of the cylinder radially inward to be recessed radially inward. The sealing body 17 is arranged on the groove 35 and is fixed to the opening of the outer can 16 by riveting through the gasket 28.

[0035] The internal space of the cylindrical battery 10 is sealed by sealing the outer can 16 and the sealing body 17 with an annular gasket 28. In addition, the gasket 28 is clamped by the outer can 16 and the sealing body 17 to insulate the sealing body 17 from the outer can 16. That is, the gasket 28 has the function of a sealing material for maintaining the airtightness inside the battery, and the function of an insulating material for insulating the outer can 16 from the sealing body 17. In addition, the gasket 28 may have a through hole 28a. By adjusting the size or shape of the through hole 28a provided in the gasket 28, the local strength (elastic force) of the gasket 28 can be adjusted.

[0036] The cylindrical battery 10 has a thin-walled portion 69 on the bottom plate 68 of the outer can 16. The thin-walled portion 69 can be formed by providing a circular or C-shaped engraving on the bottom plate 68. By providing the thin-walled portion 69 on the bottom plate 68, when the cylindrical battery 10 is abnormally heated, the bottom plate 68 can be smoothly broken starting from the thin-walled portion 69. Thus, when the cylindrical battery 10 is abnormally heated, the high-temperature gas in the battery can be smoothly discharged to the outside, and the safety of the cylindrical battery 10 can be improved.

[0037] The negative electrode current collector exposed 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. Then, the insulating plate 18 is arranged between the electrode body 14 and the upper current collector plate 50. Next, the assembly including the electrode body 14, the upper current collector plate 50 and the lower current collector plate 52 is inserted from the lower current collector plate 52 side into the outer can 16 before caulking. At this time, a part of the gasket 28 is located between the outer can 16 and the sealing body 17.

[0038] Then, the electrolyte is injected into the outer can 16 before riveting, and then the terminal cover 27 is arranged on the upper side of the upper collector plate 50 in such a way that the front end side of the convex portion 61 of the upper collector plate 50 is accommodated in the concave portion 71. Then, the above-mentioned riveting is performed to close the opening of the outer can 16. Finally, in order to improve the conductivity, the terminal cover 27 and the upper collector plate 50 are laser welded by irradiating a laser from the axial outer side of the terminal cover 27.

[0039] In detail, Figure 3As shown in the perspective view of the cylindrical battery 10 in a state cut by a plane including the central axis, the laser is irradiated in a circular manner from the axial outer side of the terminal cover 27 to the radial position corresponding to the radial center position of the annular recess 71, and the radial center portion of the recess 71 is joined to the radial center portion of the front end surface of the protrusion 61 by laser welding. By this laser welding, good conductivity between the terminal cover 27 and the upper collector plate 50 can be achieved.

[0040] By accommodating at least the front end side of the convex portion 61 provided on the upper current collector plate 50 in the concave portion 71 of the terminal cover 27, it is easy to make the upper current collector plate 50 and the terminal cover 27 close together, and as a result, the upper current collector plate 50 and the terminal cover 27 can be reliably joined by laser welding. In addition, by accommodating at least the front end side of the convex portion 61 in the concave portion 71, a labyrinth structure can be constructed between the convex portion 61 and the concave portion 71, making it difficult for the electrolyte to penetrate between the convex portion 61 and the concave portion 71. Therefore, it is possible to suppress the deterioration of the cylindrical battery 10 caused by the electrolyte penetrating between the convex portion 61 and the concave portion 71. Furthermore, it is difficult for hydrocarbons generated by gasification of the electrolyte to enter between the convex portion 61 and the concave portion 71, so it is also possible to suppress the combustion of hydrocarbons and the generation of flames during laser welding, and it is possible to manufacture high-quality cylindrical batteries 10.

[0041] In the cylindrical battery 10, the terminal cover 27 electrically connected to the plurality of positive leads 20 serves as a positive terminal, and the outer can 16 electrically connected to the negative current collector exposed portion 41 serves as a negative terminal. In addition, the upper current collector plate 50 has an annular step portion 62 extending axially downward from the protrusion 61, so that an axial gap can be provided between the second annular portion 63 and the terminal cover 27. Thus, the positive lead 20 and the metal plate 51 can be arranged in the axial gap.

[0042] Next, the detailed structure of the periphery of the protrusion 61 in the cylindrical battery 10 will be described. Figure 4 FIG. 1 is an enlarged schematic cross-sectional view of the periphery of the convex portion 61 of the cylindrical battery 10. Figure 4 and the following used Figure 5 and Figure 6 In the figure, for easy understanding, the axial length of the gap generated between the convex portion 61 of the upper current collecting plate 50 and the concave portion 71 of the terminal cover 27 is exaggerated, and the characteristics of the shape of the gap are exaggerated.

[0043] like Figure 4As shown, the cylindrical battery 10 has a joint portion 75 that joins a portion of the front end side of the convex portion 61 with a portion of the bottom of the concave portion 71. In addition, the cylindrical battery 10 has a first passage portion 76 and a second passage portion 77 between the convex portion 61 and the concave portion 71, the first passage portion 76 is adjacent to the joint portion 75 in the radial direction, and the second passage portion 77 is connected to the opposite side of the radial joint portion 75 of the first passage portion 76, and has a maximum axial length smaller than the maximum axial length of the first passage portion 76. According to this structure, the cylindrical battery 10 has the first passage portion 76 and the second passage portion 77 between the convex portion 61 and the concave portion 71. The first passage portion 76 is adjacent to the joint portion 75 in the radial direction. The second passage portion 77 is connected to the first passage portion 76 on the opposite side of the joint portion 75 with respect to the first passage portion 76. The length of the portion with the largest axial length in the second passage portion 77 is smaller than the length of the portion with the largest axial length in the first passage portion 76.

[0044] like Figure 4 As shown in FIG. 1 , in a cross section including the axial direction of the cylindrical battery 10 , the first passage portion 76 and the second passage portion 77 exist on both sides of the radial direction of the joint portion 75 . Figure 4 In the example shown, the joint portion 75, the first passage portion 76, and the second passage portion 77 extend in a circular shape when viewed from the radial direction of the cylindrical battery 10. Figure 4 As shown, in the cross section including the axial direction of the cylindrical battery 10, the second passage portion 77 includes a passage portion 81 surrounded by a first line 78 having repeated convex and concave meanders (zigzag shape) and a second line 79 having repeated convex and concave meanders. The convex portion of the first line 78 and the concave portion of the second line 79 are opposite in the axial direction, and the concave portion of the first line 78 and the convex portion of the second line 79 are opposite in the axial direction. Therefore, the passage portion 81 becomes a meandering passage portion that moves in a meandering manner.

[0045] In other words, the terminal cover 27 and the upper collector plate 50 each have a concave-convex surface that is repeatedly concave-convex in the radial direction. Moreover, the concave-convex surface of the terminal cover 27 and the concave-convex surface of the upper collector plate 50 are opposite to each other in the axial direction in such a manner that the concave-convex surface of the terminal cover 27 fits with the concave-convex surface of the upper collector plate 50 and a zigzag passage portion 81 is formed between the two concave-convex surfaces. The concave-convex surfaces of the terminal cover 27 and the upper collector plate 50 can be formed, for example, by stamping or grinding.

[0046] In addition, in the present embodiment, a zigzag passage portion 81 is formed in the entire radial area of ​​the second passage portion 77, and the second passage portion 77 is consistent with the zigzag passage portion 81. However, the zigzag passage portion may be provided only on a portion of the radial direction of the second passage portion. In addition, the structure in which the joint 75, the first passage portion 76, and the second passage portion 77 extend in a circular shape when viewed from the radial direction of the cylindrical battery 10 is described as an example, but the joint 75 does not necessarily have to be formed in a circular shape. For example, it may also be configured to form a plurality of joints in an arc shape. In addition, in the case of a structure having a plurality of joints, the first passage portion and the second passage portion are respectively provided corresponding to the plurality of joints.

[0047] As described above, after the electrolyte is injected, laser welding is performed to join the terminal cover 27 to the upper collector plate 50, so there is a risk of fire due to laser irradiation to the part where the electrolyte exists. Here, compared with the phenomenon of fire based on heat source, when the temperature of the wall near the fire part is low, the heat of the flame is taken away by the wall and the fire does not continue to burn.

[0048] In this context, according to the present embodiment, the cylindrical battery 10 includes a bottomed cylindrical outer can 16 that accommodates the electrode body 14, a terminal cover 27, a plurality of positive electrode leads 20 extending from the electrode body 14, and an upper current collector 50 to which the plurality of positive electrode leads 20 are joined. In addition, the upper current collector 50 has a convex portion 61 that protrudes toward the terminal cover 27 side in the axial direction, and the terminal cover 27 has a concave portion 71 that accommodates at least the front end side of the convex portion 61. In addition, a portion of the front end side of the convex portion 61 is joined to a portion of the bottom surface of the concave portion 71 at a joint portion 75. Furthermore, a first passage portion 76 and a second passage portion 77 are present between the convex portion 61 and the concave portion 71, the first passage portion 76 is adjacent to the joint portion 75 in the radial direction, and the second passage portion 77 is connected to the opposite side of the radial joint portion side of the first passage portion 76, and has an axial maximum length that is smaller than the axial maximum length of the first passage portion 76.

[0049] Therefore, the second passage portion 77 having a maximum axial length smaller than the maximum axial length of the first passage portion 76 exists on the opposite side of the radial joint 75 of the first passage portion 76, so that heat can be effectively absorbed by the axially opposing surfaces on both sides of the second passage portion 77 having a smaller axial length.

[0050] In addition, since the axial wall thickness of the portion of the terminal cover 27 and the portion of the upper current collector plate 50 that overlap the second passage portion 77 in the axial direction can be increased, the heat capacity of these portions can be increased, and the amount of heat that these portions can absorb can be increased. Therefore, for this reason, the fire extinguishing phenomenon can be effectively generated, so even if a flame is generated during laser welding, the flame can be extinguished in a short time, and the cylindrical battery 10 can be made into a high-quality battery.

[0051] In addition, the first passage portion 76 and the second passage portion 77 exist on both radial sides of the joint portion 75. Therefore, the radial existence range of the second passage portion 77 can be increased, and the fire extinguishing phenomenon can be more effectively produced.

[0052] Furthermore, the second passage portion 77 includes a zigzag passage portion 81 surrounded by the repeatedly zigzag first line 78 and the repeatedly zigzag second line 79. Therefore, the path length of the zigzag passage portion 81 can be increased, and the surface area of ​​the passage portion 81 can be increased. As a result, the zigzag passage portion 81 can absorb heat more effectively, and thus the fire extinguishing effect can be more effectively produced.

[0053] In addition, in the production of metal parts, sometimes the surface of the metal parts is formed with unevenness in the form of the grinding marks of the metal mold or the calendering roller being transferred to the material, but in the technology disclosed in the present invention, it is necessary to make the surface of the positive electrode cap and the upper collector plate close to each other in the axial direction, and make the close surfaces exist in a larger area. Therefore, it is preferred that the axial length of the convex part of the zigzag passage part 81 is longer than the axial length of the convex part in the unevenness based on the grinding marks of the metal mold or the calendering roller. For example, the axial length of the convex part of the passage part 81 is preferably 0.05mm to 1.5mm, and the axial length of the convex part of the passage part 81 is more preferably 0.1mm to 1.0mm.

[0054] [Fire extinguishing effect confirmation check]

[0055] The cylindrical batteries of the comparative example and the cylindrical batteries of Examples 1 to 4 were checked for the presence or absence of fire extinguishing effect.

[0056] <Cylindrical battery of comparative example>

[0057] In comparison with the cylindrical battery 10 of the above embodiment in which the terminal cover 27 and the upper current collector plate 50 are joined by the above laser welding, a cylindrical battery was produced in which only the first passage portion 76 existed but the second passage portion 77 did not exist. More specifically, in comparison with the cylindrical battery 10 of the above embodiment, a cylindrical battery was produced in which an extension of the first passage portion 76 existed at a radial position of the second passage portion 77. The axial length of the first passage portion 76 was set to 2 mm.

[0058] <Cylindrical battery of Example 1>

[0059] The cylindrical battery 10 of the above embodiment was produced. The terminal cover 27 and the upper current collecting plate 50 were joined by the above laser welding. The axial length of the zigzag second passage portion 77 was set to 0.1 mm.

[0060] <Cylindrical battery of Example 2>

[0061] The cylindrical battery 10 of the above embodiment was produced. The terminal cover 27 and the upper current collecting plate 50 were joined by the above laser welding. The axial length of the zigzag second passage portion 77 was set to 0.5 mm.

[0062] <Cylindrical battery of Example 3>

[0063] The cylindrical battery 10 of the above embodiment was produced. The terminal cover 27 and the upper current collecting plate 50 were joined by the above laser welding. The axial length of the zigzag second passage portion 77 was set to 1.0 mm.

[0064] <Cylindrical battery of Example 4>

[0065] The cylindrical battery 10 of the above embodiment was produced. The terminal cover 27 and the upper current collecting plate 50 were joined by the above laser welding. The axial length of the zigzag second passage portion 77 was set to 1.5 mm.

[0066] [Fire extinguishing effect confirmation method]

[0067] The presence or absence of burning signs was confirmed. Specifically, the presence or absence of discolored parts around the welded parts formed by laser welding was confirmed. In addition, the amount of water inside each cylindrical battery was measured. When hydrocarbons generated by electrolyte vaporization are burned, water is generated. Therefore, by measuring the amount of water, it is possible to determine whether there is burning.

[0068] [Test results]

[0069] The inspection results are shown in Table 1.

[0070] Table 1

[0071]

[0072] As shown in Table 1, no traces of burning were confirmed in all cylindrical batteries (cylindrical batteries of Examples 1-4) formed with the second passage portion 77 that zigzags. That is, it was confirmed that no burning occurred in the cylindrical batteries of Examples 1-4, or even if flames were generated, they could be extinguished in a short time. In addition, as described above, when the second passage portion is provided, the fire extinguishing effect can be improved regardless of the maximum axial length of the second passage portion. In addition, when the maximum axial length of the second passage portion is 0.1 (mm) or more, heat can be effectively absorbed by the inner surface of the second passage portion, so it is preferred. In addition, when the maximum axial length of the second passage portion is 1 (mm) or less, a fire extinguishing phenomenon can be effectively produced, so it is preferred. In addition, when the radial dimension of the existence range of the second passage portion is 0.2 (mm) or more, the contact area of ​​the part that can effectively absorb heat can be increased, and the fire extinguishing effect can be improved, so it is preferred. In addition, when the radial dimension of the existence range of the second passage portion is 1 (mm) or less, it is easy to make a compact cylindrical battery with a small radial dimension, so it is preferred.

[0073] In addition, the present disclosure is not limited to the above-described embodiment and its modified examples, and various improvements and changes can be made within the scope of the matters described in the scope of the claims of the present application and the scope of their equivalents.

[0074] For example, in the above-mentioned embodiment, the second passage portion 77 includes the zigzag passage portion 81. However, the second passage portion may not include the zigzag passage portion. Figure 5 , namely, the cylindrical battery 110 of the modified example and Figure 4 As shown in the corresponding enlarged schematic cross-sectional view, the second passage portion 177 may have a linear shape in a cross section including the axial direction of the cylindrical battery 110 .

[0075] Even if the second passage portion 177 does not include a zigzag passage portion as in the cylindrical battery 110, by reducing the axial length of the second passage portion 177, heat can be effectively absorbed by the inner surface of the second passage portion 177, and the fire extinguishing effect can be improved. In addition, the wall thickness of the portion of the terminal cover 127 overlapping with the second passage portion 177 in the axial direction and the wall thickness of the portion of the upper collector plate 150 overlapping with the second passage portion 177 in the axial direction can be increased, so the heat capacity of the overlapping portion can also be increased. Therefore, for this reason, the fire extinguishing effect can also be improved.

[0076] In the cylindrical battery 110, the portion of the terminal cover 127 overlapping the second passage portion 177 in the axial direction has a protrusion 127a protruding axially downward. In addition, the portion of the upper collector plate 150 overlapping the second passage portion 177 in the axial direction has a protrusion 150a protruding axially upward. Moreover, when the axial length of the first passage portion 176 is t1, the axial thickness of the protrusion 127a is t2, and the axial thickness of the protrusion 150a is t3, t1>(t2+t3) holds.

[0077] However, when forming the second passage portion, the protrusion may be provided only on one of the portion of the terminal cover overlapping with the second passage portion in the axial direction and the portion of the upper collector plate overlapping with the second passage portion in the axial direction. Figure 6 , that is, another modified example of the cylindrical battery 210 and Figure 4 As shown in the corresponding enlarged schematic cross-sectional view, the protrusion 227a protruding axially downward may be provided at the portion of the terminal cover 227 axially overlapping with the second passage portion 277, and the protrusion protruding axially upward may not be provided at the portion of the upper collector plate 250 axially overlapping with the second passage portion 277. Even in this way, good fire extinguishing performance can be achieved.

[0078] In addition, the case where the first passage portion 76 and the second passage portion 77 exist on both radial sides of the joint portion 75 provided by laser welding is described. However, the first passage portion and the second passage portion may exist only on one radial side of the joint provided by laser welding. In addition, the case where the cylindrical battery 10 has only one annular insulating plate 18 on the upper side of the electrode body 14 is described. However, the cylindrical battery may also have other insulating plates between the annular insulating plate and the electrode body, or may have two insulating plates in a double configuration on the upper side of the electrode body.

[0079] In addition, the case where the resistance of the cylindrical battery 10 is reduced by joining the negative electrode collector exposed portion 41 to the lower collector plate 52 and joining the lower collector plate 52 to the bottom plate portion 68 of the outer can 16 is described. However, it is also possible not to adopt a structure in which the negative electrode collector exposed portion 41 is joined to the lower collector plate 52. For example, the negative electrode lead extending from the radially inner portion of the negative electrode collector exposed portion can be joined to the bottom of the can, and the negative electrode collector without a negative electrode mixture layer can constitute the outer peripheral surface of the electrode body, so that the negative electrode collector constituting the outer peripheral surface of the electrode body is in contact with the cylindrical inner peripheral surface of the outer can. Even in this way, the resistance of the cylindrical battery can be reduced. In addition, the case where the terminal cover 27 constitutes the positive electrode and the outer can 16 constitutes the negative electrode is described. However, the polarity can be reversed, and the terminal cover can constitute the negative electrode and the outer can can constitute the positive electrode.

[0080] Description of Reference Numerals

[0081] 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 cover, 28 gasket, 40 negative electrode collector, 41 negative electrode collector exposed portion, 42 negative electrode mixture layer, 50, 150, 250 upper collector plate, 51 metal plate, 52 lower collector Plate, 60 first annular portion, 61 convex portion, 62 segment portion, 63 second annular portion, 68 bottom plate portion, 69 thin-walled portion, 71 concave portion, 75 joining 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 the terminal cover, 150a protrusion of the upper collector plate.

Claims

1. A cylindrical battery comprising: Electrode body; An outer container having a bottom and a cylindrical shape for accommodating the electrode body; a terminal cover having externally exposed terminals; a plurality of electrode leads extending from the electrode body; and a current collector to which the plurality of electrode leads are joined, The current collector plate has a convex portion protruding toward the terminal cover in the axial direction, and the terminal cover has a concave portion that accommodates at least the front end side of the convex portion. The cylindrical battery includes a joint portion that joins a portion of the front end side of the convex portion to a portion of the bottom surface of the concave portion. A first passage portion and a second passage portion are provided between the convex portion and the concave portion, the first passage portion is radially adjacent to the joining portion, the second passage portion is connected to the radial side of the first passage portion opposite to the joining portion side, and has an axial maximum length that is smaller than the axial maximum length of the first passage portion.

2. The cylindrical battery according to claim 1, The first passage portion and the second passage portion exist on both sides of the joining portion in a radial direction.

3. The cylindrical battery according to claim 1 or 2, The second passage portion has a linear shape in a cross section including the axial direction.

4. The cylindrical battery according to claim 1 or 2, In a cross section including the axial direction, the second passage portion includes a passage portion surrounded by a first line of repeated concavoconvex meandering and a second line of repeated concavoconvex meandering, The convex portion of the first line and the concave portion of the second line are opposed to each other in the axial direction, and the concave portion of the first line and the convex portion of the second line are opposed to each other in the axial direction.

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