Cylindrical battery

Abstract

This cylindrical battery (10) comprises: a bottomed tubular exterior can (16); an electrode body (14) which is housed in the exterior can (16) and around which a long positive electrode (11) and a long negative electrode (12) are wound with a separator (13) therebetween; a plurality of negative-electrode lead parts (21) extending from a long negative-electrode current collector of the negative electrode (12) toward the bottom part (68) of the exterior can (16); a first current-collector plate (40) that is disposed on the bottom part (68) side of the electrode body (14) and that has at least two through-holes (41) at the positions different from each other in the radial direction; and a second current-collector plate (45) disposed between the first current-collector plate (40) and the bottom part (68). The negative-electrode lead parts (21) each pass through any one of the through-holes (41). Leading-end portions of the plurality of negative-electrode lead parts (21) are sandwiched between the first current-collector plate (40) and the second current-collector plate (45), and are electrically connected to the second current-collector plate (45).

Description

[Technical Field]

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

[0002] A conventional cylindrical battery is described in Patent Document 1. In this cylindrical battery, multiple rectangular positive electrode leads protrude from the positive electrode toward the sealing body. The multiple positive electrode leads are sandwiched between a metal plate and a metal ring-shaped component and electrically connected to the metal plate and the ring-shaped component by laser welding. The metal plate is electrically connected to the sealing body, and the positive electrode is electrically connected to a sealing plate located at the end of the sealing body in the height direction. The sealing plate serves as the positive electrode terminal. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2001-118561 Summary of the Invention [Problem to be solved by the invention]

[0004] In the cylindrical battery, multiple positive electrode leads must be bent radially outward toward the ring-shaped member. However, the positive electrode leads protruding from the radially inner side of the electrode body have a large curvature when bent. Therefore, the positive electrode leads protruding from the radially inner side of the electrode body are likely to be subjected to large stresses and are prone to breakage. Furthermore, due to the susceptibility to breakage of the positive electrode leads, it is difficult to protrude the positive electrode leads from the radially inner end of the electrode body, limiting the radial range of the electrode body from which the positive electrode leads can be removed.

[0005] Therefore, an object of the present disclosure is to provide a cylindrical battery that allows for a high degree of freedom in the arrangement of multiple lead portions and is less likely to break the multiple lead portions. [Means for solving the problem]

[0006] In order to solve the above problems, the cylindrical battery according to the present disclosure includes a bottomed cylindrical outer can, an electrode assembly housed in the outer can and formed by winding a first elongated electrode and a second elongated electrode having opposite polarities with a separator interposed therebetween, a plurality of second electrode lead portions extending from the second electrode toward the bottom of the outer can, and a battery assembly the bottom The electrode assembly includes a first current collector plate disposed on the bottom side and having two or more through holes at different radial positions, and a second current collector plate disposed between the first current collector plate and the bottom, wherein each second electrode lead portion passes through one of the through holes, and the tip portions of the plurality of second electrode lead portions are sandwiched between the first current collector plate and the second current collector plate and are electrically connected to the second current collector plate. [Effects of the Invention]

[0007] The cylindrical battery according to the present disclosure allows for greater freedom in the placement of the multiple lead portions, and the multiple lead portions are less likely to be damaged. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is an axial cross-sectional view of a cylindrical battery according to an embodiment of the present disclosure. [Figure 2] FIG. [Figure 3] FIG. 2 is a schematic plan view of the negative electrode as viewed in its thickness direction, illustrating the structure of a negative electrode lead portion. [Figure 4] FIG. 2 is a perspective view of an electrode body with an integrated first current collector plate. [Figure 5] FIG. 10 is a perspective view of an electrode body with an integrated second current collector plate. [Figure 6] FIG. 10 is a perspective view showing a state in which the second current collector plate and the bottom of the outer can are laser-welded together. [Figure 7] FIG. 4 is a schematic plan view of a negative electrode according to a modified example, corresponding to FIG. 3. DETAILED DESCRIPTION OF THE INVENTION

[0009] 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. In the following, 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.

[0010] 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. In the following embodiments, the same components are denoted 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. In this specification, the side of the sealing body 17 in the axial direction (height direction) of the battery case 15 is referred to as "upper," and the bottom side of the outer can 16 in the axial direction is referred to as "lower." Among the components described below, components not recited in the independent claims representing the highest concepts are optional components and not essential components.

[0011] FIG. 1 is an axial cross-sectional view of a cylindrical battery 10 according to one embodiment of the present disclosure, and FIG. 2 is a perspective view of an electrode assembly 14. As shown in FIG. 1, the cylindrical battery 10 includes a wound electrode assembly 14, a non-aqueous electrolyte (not shown), and a battery case 15 that accommodates the electrode assembly 14 and the non-aqueous electrolyte. The electrode assembly 14 includes a positive electrode 11 as an example of a first electrode, a negative electrode 12 as an example of a second electrode, and a separator 13 interposed between the positive electrode 11 and the negative electrode 12. The electrode assembly 14 has a wound structure in which the positive electrode 11 and the negative electrode 12 are wound with the separator 13 interposed therebetween. The battery case 15 includes a cylindrical outer can 16 with a bottom and a sealing member 17 that closes the opening of the outer can 16. The cylindrical battery 10 also includes a resin gasket 28 disposed between the outer can 16 and the sealing member 17.

[0012] The non-aqueous electrolyte includes a non-aqueous solvent and an electrolyte salt dissolved in the non-aqueous solvent. Examples of the non-aqueous solvent include esters, ethers, nitriles, amides, and mixtures 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 is a lithium salt such as LiPF6.

[0013] 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. A positive electrode lead 20 is joined to the positive electrode 11, and multiple negative electrode lead portions 21 (only one is shown in FIG. 2) are electrically connected to the negative electrode 12. The negative electrode lead portion 21 constitutes a second electrode lead portion. The structure of the multiple negative electrode lead portions 21 will be described in detail later with reference to FIG. 3. The negative electrode 12 is formed to be slightly larger than the positive electrode 11 in order to suppress lithium deposition, and is formed to be longer than the positive electrode 11 in the longitudinal direction and width direction (short direction). The two separators 13 are formed to be at least slightly larger than the positive electrode 11 and are arranged, for example, to sandwich the positive electrode 11.

[0014] 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 current collector.

[0015] 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.

[0016] Examples of conductive agents contained in the positive electrode mixture layer include carbon materials such as carbon black, acetylene black, ketjen black, and graphite. Examples of binders 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).

[0017] The negative electrode 12 has a negative electrode current collector and a negative electrode mixture layer formed on both sides of the negative electrode current collector. The negative electrode current collector can be 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 the surface layer. The negative electrode mixture layer 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 onto the negative electrode current collector, drying the coating, and then compressing it to form a negative electrode mixture layer on both sides of the current collector.

[0018] 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 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.

[0019] The binder contained in the negative electrode mixture layer may be a fluororesin, PAN, polyimide resin, acrylic resin, polyolefin resin, or the like, as in the case of the positive electrode 11. Preferably, styrene-butadiene rubber (SBR) or a modified product thereof is used. The negative electrode mixture layer may contain, in addition to SBR, for example, CMC or a salt thereof, polyacrylic acid (PAA) or a salt thereof, polyvinyl alcohol, or the like.

[0020] The separator 13 is a porous sheet having ion permeability and insulating properties. 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. The negative electrode 12 may form the winding start end of the electrode assembly 14, but 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.

[0021] As shown in Figure 1, cylindrical battery 10 includes insulating plate 18 disposed on the upper side of electrode body 14. Positive electrode lead 20 attached to positive electrode 11 passes through a through-hole in insulating plate 18 and extends toward sealing body 17. Positive electrode lead 20 is connected by welding or the like to the underside of terminal plate 23, which is the bottom plate of sealing body 17, and sealing plate 27, which is the top plate of sealing body 17 and is electrically connected to terminal plate 23, serves as the positive electrode terminal.

[0022] The cylindrical battery 10 includes a first current collector plate 40 disposed below the electrode body 14 and a second current collector plate 45 disposed below the first current collector plate 40. The first current collector plate 40 has a plurality of through holes 41. Each negative electrode lead portion 21 passes through one of the through holes 41 and is then bent radially inward or outward. As will be described in detail later, the plurality of through holes 41 are located at different radial positions. Furthermore, the negative electrode lead portion 21 extending from the radially inner side of the electrode body 14 passes through a through hole 41 located on the radially inner side and is then bent radially outward, while the negative electrode lead portion 21 extending from the radially outer side of the electrode body 14 passes through a through hole 41 located on the radially outer side and is then bent radially inward.

[0023] The tip portions 21a of the plurality of negative electrode lead portions 21 are sandwiched between the first current collector plate 40 and the second current collector plate 45. The tip portions 21a of the plurality of negative electrode lead portions 21 are joined to at least the second current collector plate 45 located below. In this case, it is not necessary that the tip portions 21a of all of the negative electrode lead portions 21 are joined to the second current collector plate 45. As long as the tip portion 21a of at least one negative electrode lead portion 21 is joined to the second current collector plate 45, the tip portions 21a of all of the negative electrode leads 21 can be electrically connected to the second current collector plate 45 by joining the tip portions 21a of the negative electrode lead portions 21 to each other. The plurality of negative electrode lead portions 21 are preferably also joined to the first current collector plate 40 located above. The first current collector plate 40 has a fitting portion 51 that protrudes axially upward and fits into the hollow portion of the electrode body 14. The fitting portion 51 includes a cylindrical portion 52 fitted into the hollow portion of the electrode body 14, and a disk portion 53 connected to the upper end of the cylindrical portion 52 and closing the upper opening of the cylindrical portion 52. A through-hole 54 passing through the disk portion 53 in the axial direction is provided in the radial center of the disk portion 53. The outer can 16 is a metal container having a cylindrical portion with a bottom. The second current collector 45 is joined to the bottom 68 of the outer can 16.

[0024] The gap between the outer can 16 and the sealing body 17 is sealed with an annular gasket 28, thereby sealing the internal space of the battery case 15. The gasket 28 is also sandwiched between the outer can 16 and the sealing body 17, and insulates 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 insulating material to insulate the outer can 16 and the sealing body 17.

[0025] The outer can 16 has an annular grooved portion 35 along a portion of the cylindrical outer surface in the height direction. The grooved portion 35 can be formed, for example, by spinning a portion of the cylindrical outer surface radially inward to create a recess in the radial direction. The outer can 16 has a bottomed tubular portion 30 including the grooved portion 35 and an annular shoulder portion 33. The bottomed tubular portion 30 accommodates the electrode assembly 14 and the nonaqueous electrolyte, and the shoulder portion 33 is bent radially inward from the end of the open side of the bottomed tubular portion 30 and extends inward. The shoulder portion 33 is formed when the upper end of the outer can 16 is bent inward and crimped to the peripheral edge 31 of the sealing body 17. The sealing body 17 is crimped to the outer can 16 with a gasket 28 interposed between the shoulder portion 33 and the grooved portion 35.

[0026] [Cylindrical battery of the embodiment] Next, an example of a method for producing the cylindrical battery 10 will be specifically described. <Preparation of positive electrode> LiNi as the positive electrode active material 0.8 Co 0.15 Al 0.05 O2 was used. A positive electrode mixture paste was prepared by mixing 100 parts by weight of the positive electrode active material, 1.7 parts by weight of polyvinylidene fluoride as a binder, and 2.5 parts by weight of acetylene black as a conductive agent with a liquid component. The positive electrode mixture paste was applied to both sides of an aluminum foil positive electrode current collector, excluding the connection portion of the positive electrode lead, and dried. The positive electrode was then rolled to a predetermined thickness to obtain a positive electrode. The positive electrode was cut to the predetermined dimensions, and an aluminum positive electrode lead was connected to the exposed portion of the current collector by ultrasonic welding.

[0027] <Preparation of negative electrode> Graphitizable carbon was used as the negative electrode active material. 100 parts by mass of the negative electrode active material, 0.6 parts by mass of polyvinylidene fluoride as a binder, 1 part by mass of carboxymethyl cellulose as a thickener, and an appropriate amount of water were mixed in a twin-arm kneader to form a negative electrode. combination drug The negative electrode mixture paste was applied to both sides of a long negative electrode current collector made of copper foil. When applying the paste to both sides, the negative electrode mixture paste was applied to predetermined regions in the width direction of the long negative electrode current collector on both sides. combination drug A non-coated portion was provided where no paste was applied. Subsequently, both sides of the negative electrode current collector were dried, and then the negative electrode was obtained by rolling to a predetermined thickness. The negative electrode was then cut to a predetermined size so that a non-coated portion was formed on one side in the width direction of the negative electrode. The non-coated portion made of copper foil was then subjected to a press punching process to form a plurality of negative electrode lead portions 21 made up of a portion of the non-coated portion.

[0028] FIG. 3 is a schematic plan view of the fabricated negative electrode 12 as viewed in its thickness direction, and is a schematic plan view for explaining the structure of the negative electrode lead portion 21. Note that the left edge of the paper in FIG. 3 is the winding start end. As shown in FIG. 3, the negative electrode 12 includes a negative electrode current collector 25 and a negative electrode mixture layer 26 provided on both sides of the negative electrode current collector 25. The negative electrode current collector 25 is made of, for example, copper foil. A non-coated portion 29 where the negative electrode current collector 25 is exposed is provided on one side in the width direction of both sides of the negative electrode 12. A portion of the non-coated portion 29 protrudes in the width direction of the negative electrode 12, thereby forming a plurality of negative electrode lead portions 21. That is, the plurality of negative electrode lead portions 21 are formed from the metal foil (copper foil in this embodiment) that constitutes the negative electrode current collector 25. The plurality of negative electrode lead portions 21 are formed integrally with the negative electrode current collector 25 by the press punching process.

[0029] The multiple negative electrode lead portions 21 are arranged at intervals from one another in the longitudinal direction of the negative electrode 12. In this embodiment, the multiple negative electrode lead portions 21 are configured as four sets of negative electrode lead pairs 37, and each set of negative electrode lead pair 37 is configured as two negative electrode lead portions 21 arranged at an interval in the longitudinal direction of the negative electrode 12. The longitudinal interval between the two negative electrode lead portions 21 constituting each negative electrode lead pair 37 gradually increases toward the end of the winding. As will be described later, the two negative electrode lead portions 21 constituting each negative electrode lead pair 37 pass through the same through-hole 41 in the first current collector plate 40. The multiple negative electrode lead portions 21 have approximately the same length.

[0030] <Preparation of non-aqueous electrolyte> A non-aqueous electrolyte solution was prepared by dissolving lithium hexafluorophosphate (LiPF6) as an electrolyte in a mixed solvent of ethylene carbonate (EC), diethyl carbonate (DEC), and ethyl methyl carbonate (EMC) to a concentration of 1.0 mol / L.

[0031] <Preparing the sealing body> Thin portion 23a (see FIG. 1) was provided in the center of metal terminal plate 23, which was circular in plan view, and then terminal plate 23, annular insulating plate 24 (see FIG. 1), and sealing plate 27 were integrated to produce sealing body 17. Thin portion 23a was joined to the center of the underside of sealing plate 27 by welding.

[0032] <Battery assembly> The positive electrode 11 and the negative electrode 12 were spirally wound with a polyolefin resin separator 13 interposed therebetween to produce an electrode body 14. Then, the electrode body 14, the first current collector plate 40, and the second current collector plate 45 were integrated into one body. The first current collector plate 40 and the second current collector plate 45 were each made of a nickel (Ni) plate having the structure described below.

[0033] First to fourth through holes 41a, 41b, 41c, and 41d (see FIG. 4) are provided at different radial positions on the first current collector plate 40. The first through hole 41a is located radially inward from the second through hole 41b, the second through hole 41b is located radially inward from the third through hole 41c, and the third through hole 41c is located radially inward from the fourth through hole 41d. The first to fourth through holes 41a, 41b, 41c, and 41d are arranged at equal intervals in the circumferential direction. The first current collector plate 40 is provided with the above-mentioned fitting portion 51 (see FIG. 1), while the second current collector plate 45 is a disc-shaped member. The second current collector plate 45 differs from the first current collector plate 40 only in that it does not have the fitting portion 51 protruding toward the electrode body 14. In this embodiment, the second current collector plate 45 has the through-holes 47 (see FIG. 1), but the second current collector plate does not necessarily have to have the through-holes.

[0034] The electrode body 14, first current collector plate 40, and second current collector plate 45 were integrated as follows. First, as shown in FIGS. 1, 3, and 4, the fitting portion 51 (see FIG. 1) of the first current collector plate 40 was fitted into the hollow portion of the electrode body 14, and at the same time, the negative electrode lead portion 21 was passed through the through hole 41 of the first current collector plate. More specifically, this is as follows. The first negative electrode lead pair 37a (see FIGS. 3 and 4) located closest to the start of winding was passed through the first through hole 41a (see FIG. 4) of the first current collector plate 40. The second negative electrode lead pair 37b located second closest to the start of winding was passed through the second through hole 41b of the first current collector plate 40. The third negative electrode lead pair 37c located third closest to the start of winding was passed through the third through hole 41c of the first current collector plate 40. The fourth negative electrode lead pair 37d located on the outermost side in the radial direction was passed through the fourth through-hole 41d of the first current collector plate 40.

[0035] Next, as shown in FIG. 4, the portions of the first negative electrode lead pair 37a and the second negative electrode lead pair 37b protruding from the first and second through holes 41a, 41b were bent radially outward, and the portions of the third negative electrode lead pair 37c and the fourth negative electrode lead pair 37d protruding from the third and fourth through holes 41c, 41d were bent radially inward. In this manner, all of the negative electrode lead portions 21 were bent onto the first current collector plate 40. Thereafter, as shown in FIG. 5, a second current collector plate 45 was placed on the bent negative electrode lead portions 21, and then a laser beam was irradiated onto the second current collector plate 45 from the axially outer side of the second current collector plate 45. In this manner, the negative electrode lead portion 21 made of copper foil was joined to the second current collector plate 45 by laser welding, and the electrode body 14, the first current collector plate 40, and the second current collector plate 45 were integrated into one body.

[0036] 5 and the following FIG. 6, the areas painted black are areas irradiated with laser light. The wavelength and intensity of the laser light used in laser welding can be changed as appropriate based on the thickness of the second current collector plate 45, etc. This laser welding can also join the second current collector plate 45 and the negative electrode lead 21 and the first current collector plate 40 at the same time.

[0037] Next, as shown in FIG. 6 , the electrode assembly 14, in which the first and second current collector plates 40 and 45 are integrated, is inserted into the outer can 16, and laser welding is performed by irradiating a laser beam from the bottom 68 side of the outer can 16 to join the bottom 68 and the second current collector plate 45. As shown in FIG. 6 , it is preferable to irradiate the entire circumferential area with the laser beam, as this ensures reliable joining of the bottom 68 and the second current collector plate 45. For example, as shown in FIG. 6 , the laser beam is irradiated to an annular area that is concentric with the bottom 68, which has a circular shape in a plan view when viewed from the axial direction. The laser beam irradiation area can be set to any area of ​​the bottom 68 facing the second current collector plate 45 without any particular limitations. The wavelength and intensity of the laser beam used in the laser welding can be appropriately changed depending on the thickness of the bottom 68, etc. Thereafter, the positive electrode lead 20 connected to the positive electrode 11 and the sealing body 17 are connected by welding. Next, after pouring an electrolyte into the outer can 16, the sealing member 17 was inserted into the outer can 16, and the side surface of the outer can 16 and the sealing member 17 were crimped together to produce the cylindrical battery 10.

[0038] [Essential configurations of the cylindrical battery of the present disclosure and their effects] As described above, the cylindrical battery 10 of the present disclosure includes a bottomed cylindrical outer can 16, an electrode assembly 14 housed within the outer can 16 and formed by winding an elongated positive electrode 11 (first electrode) and an elongated negative electrode 12 (second electrode) with a separator 13 interposed therebetween, and a plurality of negative electrode lead portions 21 (second electrode lead portions) extending from an elongated negative electrode current collector 25 of the negative electrode 12 toward a bottom 68 of the outer can 16. The cylindrical battery 10 also includes a first current collector 40 disposed on the bottom 68 side of the electrode assembly 14 and having two or more through holes 41a, 41b, 41c, and 41d positioned at different radial positions, and a second current collector 45 disposed between the first current collector 40 and the bottom 68. Each negative electrode lead portion 21 passes through one of the through holes 41. Furthermore, the tip portions of the plurality of negative electrode lead portions 21 are sandwiched between the first current collector plate 40 and the second current collector plate 45 and are electrically connected to the second current collector plate 45 .

[0039] Therefore, the through-hole for passing the negative electrode lead portion 21 through can be provided at any position in the first current collector plate 40, and the negative electrode lead portion 21 can be freely taken out from any position in the longitudinal direction of the negative electrode 12, for example, from the end portion on the winding start side in the longitudinal direction of the negative electrode 12. Therefore, the multiple negative electrode lead portions 21 can be evenly and entirely dispersed in the longitudinal direction of the negative electrode 12, which makes it easier to reduce the internal resistance of the cylindrical battery 10.

[0040] By providing the through hole 41 in the first current collector plate 40 at a position suitable for passing the negative electrode lead portion 21, the negative electrode lead portion 21 can be passed through the through hole 41 and bent toward the first current collector plate 40 without applying stress to the negative electrode lead portion 21, and damage to the negative electrode lead portion 21 can also be suppressed. Furthermore, since the position of the tip end of each negative electrode lead portion 21 relative to the radial direction of the second current collector plate can be easily adjusted, each negative electrode lead portion 21 can be reliably and easily joined to the second current collector plate 45 by laser welding or the like. Furthermore, since the above adjustment can be made even when the lengths of the negative electrode lead portions 21 are uniform as shown in FIG. 3, processing of the negative electrodes 12 can be facilitated.

[0041] Furthermore, since the multiple negative electrode lead portions 21 can be joined to the second current collector plate 45 while being restrained by the first current collector plate 40 and the second current collector plate 45, the joining can be performed reliably. Furthermore, when laser welding is used for joining, the first current collector plate 40 can be used as a laser welding receiver. That is, when the negative electrode lead portions 21 and the second current collector plate 45 are joined by irradiating laser light from the underside of the second current collector plate 45 (the side opposite the first current collector plate 40 in the axial direction), spatter is generated. However, this spatter can be received by the first current collector plate 40, and the intrusion of the spatter into the electrode body 14 can be prevented. Therefore, a high-quality cylindrical battery 10 can be manufactured.

[0042] [Preferable cylindrical battery configuration and its effects] The plurality of negative electrode lead portions 21 are preferably formed from the metal foil that constitutes the negative electrode current collector 25 .

[0043] With the above configuration, the negative electrode lead portion 21 is easy to bend, and the bending process can be easily performed. Furthermore, because the thickness of the negative electrode lead portion 21 can be made thin, it is easy to increase the number of windings of the electrode body 14 and the capacity of the cylindrical battery 10. Furthermore, the negative electrode lead portion 21 can be manufactured simply and inexpensively.

[0044] In addition, it is preferable that a plurality of negative electrode lead portions 21 are joined to the first current collector plate 40 .

[0045] The above configuration makes it possible to further ensure the electrical connection between the plurality of negative electrode lead portions 21 and the second current collector plate 45. Furthermore, the first current collector plate 40 can be fixed inside the outer can 16.

[0046] Moreover, it is preferable that the first current collector plate 40 has a fitting portion 51 that fits into the hollow portion of the electrode body 14 .

[0047] According to the above configuration, the first current collector plate 40 can be positioned with high precision in the radial direction relative to the electrode body 14, and the through hole 41 can be positioned with high precision relative to the electrode body 14. Therefore, the negative electrode lead portion 21 can be easily passed through the through hole 41.

[0048] Furthermore, because the electrode body 14 receives a radially outward force from the fitting portion 51, it is possible to prevent the electrode body 14 from expanding toward the hollow portion during charging and discharging of the cylindrical battery 10. This prevents deformation of the positive electrode 11 and negative electrode 12, and thus prevents capacity degradation of the cylindrical battery.

[0049] As shown in FIG. 1 , the fitting portion 51 has a through-hole 54 extending in the axial direction. This through-hole 54 is provided to allow high-temperature gas generated when the cylindrical battery 10 generates abnormal heat to pass through the hollow portion of the electrode body 14 and flow toward the sealing body 17. The fitting portion may have any structure as long as it can fit into the hollow portion of the electrode body 14 and allow high-temperature gas to pass through the hollow portion of the electrode body. For example, the fitting portion may be cylindrical. Furthermore, the fitting portion may be a tapered cylindrical shape with a conical outer circumferential surface that tapers toward the upper side in the axial direction. If the fitting portion has a cylindrical shape that tapers toward the upper side, damage to the electrode body 14 due to contact with the fitting portion when the fitting portion is fitted into the hollow portion can be suppressed.

[0050] [Variations] The present disclosure is not limited to the above-described embodiment and its variations, and various improvements and modifications are possible within the scope of the claims of the present application and their equivalents. In the above-described embodiment, as shown in Figures 3 and 4, through holes 41a, 41b, 41c, and 41d are provided in four non-overlapping circumferential regions of the cylindrical battery 10, and two negative electrode lead portions 21 are led out from each of the through holes 41a, 41b, 41c, and 41d. The number of through holes and the number of negative electrode lead portions passing through each through hole can be changed as desired.

[0051] In addition, the case where all of the through holes 41a, 41b, 41c, and 41d in the first current collector plate 40 are at different radial positions has been described. However, the multiple through holes in the first current collector plate may include two or more through holes at the same radial position. If two through holes do not substantially overlap when moved circumferentially, their radial positions are determined to be different from each other. Furthermore, the multiple through holes in the first current collector plate may include two or more through holes that overlap at least partially in the circumferential position but do not overlap in the radial position.

[0052] In the example, the plurality of negative electrode lead portions 21 are formed integrally with the negative electrode current collector 25 by press-punching the metal foil. However, the plurality of negative electrode lead portions may also be formed by cutting the metal foil using a laser beam.

[0053] 7, that is, a schematic plan view of a modified negative electrode 112 corresponding to FIG. 3, a plurality of negative electrode lead portions 121 may be formed by joining a plurality of metallic (e.g., copper) lead plates to a non-coated portion 129 of a negative electrode current collector 125 that is adjacent to the negative electrode mixture layer 126 in the width direction. According to this modification, the thickness of the negative electrode lead portion 121 can be adjusted, and the strength of the negative electrode lead portion 121 can also be adjusted.

[0054] Furthermore, in the electrode assembly 14, the axial length of the separator 13 is longer than the axial length of the positive electrode 11 and the axial length of the negative electrode 12. Therefore, even if a first current collector plate 40 is placed below the electrode assembly 14, the separator 13 will not get in the way and the positive electrode 11 and negative electrode 12 will not be short-circuited via the first current collector plate 40. However, an insulating layer may be placed between the electrode assembly 14 and the first current collector plate 40.

[0055] Although the second current collector plate 45 and the plurality of negative electrode lead portions 21 were joined by laser welding, the second current collector plate and the plurality of negative electrode lead portions may also be joined by resistance welding or ultrasonic welding. Furthermore, the bottom 68 of the outer can 16 and the second current collector plate 45 were joined by laser welding, but the bottom of the outer can and the second current collector plate may also be joined by resistance welding or ultrasonic welding. Furthermore, although the case where the first current collector plate 40 has a fitting portion 51 that fits into the hollow portion of the electrode body 14 has been described, the first current collector plate does not have to have a fitting portion that fits into the hollow portion of the electrode body.

[0056] Although the case where the first current collector 40 is joined to the second current collector 45 and the plurality of negative electrode lead portions 21 has been described, the first current collector 40 does not have to be joined to both the plurality of negative electrode lead portions 21 and the second current collector 45. Furthermore, although nickel is used as the material for the first and second current collectors 40, 45, other metals such as cast iron, copper, or nickel-plated iron may also be used as the material for the first and second current collectors.

[0057] In one embodiment of the present disclosure, the case where the second electrode electrically connected to the outer can 16 is a negative electrode has been described. However, the first electrode may be a negative electrode and the second electrode may be a positive electrode. In this case, the outer can serves as the positive electrode terminal. [Explanation of symbols]

[0058] 10 Cylindrical battery, 11 Positive electrode, 12,112 Negative electrode, 13 Separator, 14 Electrode body, 15 Battery case, 16 Outer can, 17 Sealing body, 18 Insulating plate, 20 Positive electrode lead, 21,121 Negative electrode lead portion, 23 Terminal plate, 24 Insulating plate, 25,125 Negative electrode current collector, 26,126 Negative electrode mixture layer, 27 Sealing plate, 28 Gasket, 29,129 Non-coated portion, 37 Negative electrode lead pair, 37a First negative electrode lead pair, 37b Second negative electrode lead pair, 37c Third negative electrode lead pair, 37d Fourth negative electrode lead pair, 40 First current collector plate, 41 Through hole, 41a First through hole, 41b Second through hole, 41c third through hole, 41d fourth through hole, 45 second current collecting plate, 51 fitting portion, 54 through hole, 68 bottom of outer can.

Claims

1. a cylindrical outer can with a bottom; an electrode assembly housed in the outer can, the electrode assembly being formed by winding a first elongated electrode and a second elongated electrode having opposite polarities with a separator interposed therebetween; a plurality of second electrode lead portions extending from the second electrode toward the bottom of the outer can; a first current collecting plate disposed on the bottom side of the electrode body and having two or more through holes positioned at different radial positions; a second current collecting plate disposed between the first current collecting plate and the bottom portion; Each of the second electrode lead portions passes through one of the through holes, a cylindrical battery, wherein the tip ends of the plurality of second electrode lead portions are sandwiched between the first current collector plate and the second current collector plate and are electrically connected to the second current collector plate.

2. The cylindrical battery according to claim 1 , wherein the plurality of second electrode lead portions are formed from a metal foil that constitutes a current collector of the second electrode.

3. The cylindrical battery according to claim 1 or 2, wherein at least one of the plurality of second electrode lead portions is joined to the first current collector plate.

4. The cylindrical battery according to claim 1 , wherein the first current collector plate has a fitting portion that fits into the hollow portion of the electrode body.

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