Cylindrical battery

Abstract

A battery (10) comprises: an electrode body (14) in which a positive electrode (11) and a negative electrode (12) are wound with a separator (13) interposed therebetween; a positive electrode lead (16) electrically connected to the electrode body (14); and an exterior can (20) that accommodates the electrode body (14) and the positive electrode lead (16). The positive electrode lead (16) has a small cross-sectional region (55) having a small cross-sectional area outside the electrode body (14). The small cross-sectional region (55) is preferably covered with tape such as insulating tape (51) or heat-insulating tape. According to the present disclosure, it is possible to provide a battery (10) in which appropriate current interruption is easily achieved when abnormal heat generation occurs.

Description

Cylindrical battery

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

[0002] Conventionally, as a battery, there is a cylindrical battery described in Patent Document 1. This cylindrical battery includes an electrode body in which a positive electrode and a negative electrode are wound with a separator interposed therebetween, an outer can that houses the electrode body, and a sealing body that seals an opening located on one axial side of the outer can through a gasket. The positive electrode is electrically connected to the sealing body, and the negative electrode is electrically connected to the outer can. The sealing body has a current interruption mechanism that interrupts the electrical connection between the positive electrode and the sealing body when the internal pressure of the battery rises due to abnormal heat generation of the battery. The current interruption mechanism is provided to suppress further heat generation when the battery abnormally generates heat and is provided to achieve high safety.

[0003] Japanese Unexamined Patent Application Publication No. 2016-225014

[0004] Even if the current interruption mechanism does not appropriately interrupt due to some problem, high safety can be achieved if the current to the sealing body can be interrupted. Also, there may be a case where the cylindrical battery does not have a current interruption mechanism and the outer can has a thin and easily breakable portion at the bottom. Even in this case, high safety can be achieved if the current to the sealing body can be interrupted before the breakage of the easily breakable portion. Therefore, an object of the present disclosure is to provide a cylindrical battery that can easily achieve appropriate current interruption when abnormal heat generation occurs.

[0005] To solve the above problems, the cylindrical battery according to the present disclosure includes an electrode body in which a positive electrode and a negative electrode are wound with a separator interposed therebetween, an electrode lead electrically connected to the electrode body, and an outer can that houses the electrode body and the electrode lead, and the electrode lead has a small cross-sectional area region with a small cross-sectional area outside the electrode body.

[0006] According to the cylindrical battery according to the present disclosure, appropriate current interruption can be easily achieved when abnormal heat generation occurs.

[0007] This is an axial cross-sectional view of a cylindrical battery according to one embodiment of the present disclosure. This is a schematic diagram showing the area around the positive electrode lead junction in the strip-shaped positive electrode and a part of the positive electrode lead. This is a schematic diagram corresponding to Figure 2 in the first modified cylindrical battery. This is a schematic diagram corresponding to Figure 2 in the second modified cylindrical battery.

[0008] Hereinafter, embodiments of the cylindrical battery according to this disclosure will be described in detail with reference to the drawings. The cylindrical battery of this 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 lithium-ion secondary battery is given as an example of a cylindrical battery 10 in one embodiment, but the cylindrical battery of this disclosure is not limited to this.

[0009] It is intended from the outset that new embodiments can be constructed by appropriately combining the characteristic features of the embodiments and modifications described below. In the following embodiments, the same reference numerals are used for the same components in the drawings, and redundant explanations are omitted. In addition, multiple drawings include schematic diagrams, and the dimensional ratios such as length, width, and height of each component do not necessarily match between different drawings. In this specification, the axial (height direction) sealing body 19 side of the cylindrical battery 10 is referred to as "top," and the axial bottom 20A side of the outer casing 20 is referred to as "bottom." Among the components described below, components that are not described in the independent claim indicating the highest-level concept are optional components and are not essential components.

[0010] Figure 1 is an axial cross-sectional view of a cylindrical battery 10 according to one embodiment of the present disclosure. As shown in Figure 1, the cylindrical battery (hereinafter simply referred to as "battery") 10 comprises an electrode body 14, a non-aqueous electrolyte, a bottomed cylindrical outer casing 20 housing the electrode body 14 and the non-aqueous electrolyte, and a sealing body 19 that closes the opening of the outer casing 20 via an annular gasket 24. In the example shown in Figure 1, the outer casing 20 has a bottomed cylindrical shape, but the outer casing may have openings at both the upper and lower ends, and each opening may be closed by one or more members.

[0011] The electrode body 14 includes a long positive electrode 11, a long negative electrode 12, and two long separators 13 interposed between the positive electrode 11 and the negative electrode 12, and has a wound structure in which the positive electrode 11 and the negative electrode 12 are wound around the separators 13. The negative electrode 12 is formed to be slightly larger in dimensions than the positive electrode 11 in order to prevent lithium deposition. The negative electrode 12 is formed to be longer than the positive electrode 11 in the winding direction and in the axial direction. The two separators 13 are formed to be slightly larger in dimensions than the positive electrode 11 and are arranged to sandwich the positive electrode 11. The separators 13 protrude above and below the positive electrode 11 and the negative electrode 12.

[0012] Non-aqueous electrolytes are ionic conductive (e.g., lithium ion conductive). Non-aqueous electrolytes may be liquid electrolytes (electrolytes) or solid electrolytes. Liquid electrolytes (electrolytes) contain a non-aqueous solvent and an electrolyte salt dissolved in the non-aqueous solvent. Examples of non-aqueous solvents include esters, ethers, nitriles, amides, and mixtures of two or more of these. Examples of non-aqueous solvents include ethylene carbonate (EC), ethyl methyl carbonate (EMC), dimethyl carbonate (DMC), diethyl carbonate (DEC), and mixtures thereof. Non-aqueous solvents may contain halogen-substituted compounds (e.g., fluoroethylene carbonate) in which at least some of the hydrogen atoms in these solvents are replaced with halogen atoms such as fluorine. Examples of electrolyte salts include LiPF4. ６ Lithium salts such as these are used.

[0013] As solid electrolytes, for example, solid or gel-like polymer electrolytes, inorganic solid electrolytes, etc., are used. Polymer electrolytes include, for example, a lithium salt and a matrix polymer, or a non-aqueous solvent, a lithium salt and a matrix polymer. As matrix polymers, for example, polymer materials that absorb non-aqueous solvents and gel are used. As polymer materials, for example, fluororesins, acrylic resins, polyether resins, etc., are used. As inorganic solid electrolytes, for example, materials known for all-solid-state lithium-ion secondary batteries, etc. (for example, oxide-based solid electrolytes, sulfide-based solid electrolytes, halide-based solid electrolytes, etc.) are used.

[0014] The positive electrode 11 has a positive electrode core 45 (see Figure 2) and positive electrode mixture layers 46 (see Figure 2) formed on both sides of the positive electrode core 45. The positive electrode core 45 can be made of a metal foil that is stable in the potential range of the positive electrode 11, such as aluminum or an aluminum alloy, or a film with the metal arranged on its surface. The positive electrode mixture layers 46 contain a positive electrode active material, a conductive agent, and a binder. The positive electrode 11 is manufactured, for example, by applying a positive electrode mixture slurry containing a positive electrode active material, a conductive agent, and a binder onto the positive electrode core 45, drying the coating, and then compressing it to form the positive electrode mixture layers 46 on both sides of the positive electrode core 45.

[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. A preferred example of a lithium-containing metal composite oxide is a composite oxide containing at least one of Ni, Co, Mn, and Al.

[0016] Examples of conductive agents included in the positive electrode mixture layer 46 include carbon black such as acetylene black and Ketjen black, and carbon materials such as graphite. Examples of binders included in the positive electrode mixture layer 46 include fluororesins such as polytetrafluoroethylene (PTFE) and polyvinylidene fluoride (PVdF), polyacrylonitrile (PAN), polyimide resin, acrylic resin, and polyolefin resin. These resins may be used in combination with cellulose derivatives such as carboxymethylcellulose (CMC) or its salts, polyethylene oxide (PEO), etc.

[0017] The negative electrode 12 comprises a negative electrode core and negative electrode mixture layers formed on both sides of the negative electrode core. The negative electrode core can be made of a metal foil that is stable within the potential range of the negative electrode 12, such as copper or a copper alloy, or a film with the metal arranged on its surface. The negative electrode mixture layers contain a negative electrode active material and a binder. The negative electrode 12 is manufactured, for example, by applying a negative electrode mixture slurry containing the negative electrode active material and binder onto the negative electrode core, drying the coating, and then compressing it to form the negative electrode mixture layers on both sides of the negative electrode core.

[0018] Generally, carbon materials that reversibly intercept and release lithium ions are used as the negative electrode active material. Preferred carbon materials are graphite such as natural graphite such as flake graphite, lump graphite, and clay graphite, and artificial graphite such as lump graphite and graphitized mesophase carbon microbeads. The negative electrode mixture layer may contain silicon (Si) material as the negative electrode active material. In addition, metals that alloy with lithium other than Si, alloys containing such metals, compounds containing such metals, etc., may be used as the negative electrode active material.

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

[0020] A porous sheet having ion permeability and insulating properties is used for the separator 13. Specific examples of porous sheets include microporous thin films, woven fabrics, and nonwoven fabrics. The material of the separator 13 is preferably polyethylene, polyolefin resins such as polypropylene, or 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.

[0021] As shown in Figure 1, an upper insulating plate 15 is positioned above the electrode body 14, and a lower insulating plate 16 is positioned below the electrode body 14. In the example shown in Figure 1, the positive electrode lead 17 attached to the positive electrode 11 extends through a through-hole in the upper insulating plate 15 towards the sealing body 19 and is connected to the lower surface of the sealing body 19 by welding or the like. On the other hand, the negative electrode lead 18 attached to the negative electrode 12 extends outside the lower insulating plate 16 towards the bottom 20A of the outer casing 20 and is connected to the inner surface of the bottom 20A by welding or the like. The sealing body 19 to which the positive electrode lead 17 is connected becomes the positive electrode terminal, and the outer casing 20 to which the negative electrode lead 18 is connected becomes the negative electrode terminal. As will be explained in detail later using Figures 2 to 4, the positive electrode lead 17 is an example of an electrode lead having a region with a smaller cross-sectional area.

[0022] The case described above has been one in which the battery 10 has a single negative electrode lead 18 extending from the radial end of the electrode body 14 toward the bottom 20A. However, the battery may also have a plurality of negative electrode leads that electrically connect the negative electrode of the electrode body to the bottom of the outer casing, and one end of each of the plurality of negative electrode leads may be joined to the negative electrode at intervals in the longitudinal direction of the negative electrode. Alternatively, one axial end of the electrode body may be a strip-shaped negative electrode core exposed portion, and this negative electrode core exposed portion may be joined to the bottom of the outer casing via a negative electrode current collector plate for electrical connection.

[0023] Furthermore, at least a portion of the outermost surface of the electrode body may be composed of an exposed negative electrode core, and this exposed negative electrode core may be in contact with the inner surface of the outer can. In this case, the end of the negative electrode of the electrode body on the winding start side may be electrically connected to the bottom of the outer can via a negative electrode lead passing through a through hole in the lower insulating plate. This effectively shortens the current path on the negative electrode side and effectively reduces electrical resistance. Even if the exposed negative electrode core is not in contact with the inner surface of the outer can, the end of the negative electrode of the electrode body on the winding start side may be electrically connected to the bottom of the outer can via a negative electrode lead passing through a through hole in the lower insulating plate.

[0024] A gasket 24 is provided between the outer casing 20 and the sealing body 19 to ensure airtightness inside the battery and insulation between the outer casing 20 and the sealing body 19. The outer casing 20 has a cylindrical portion 20B and a bottom portion 20A, and the cylindrical portion 20B includes an annular grooved portion 28 and an annular shoulder portion 29. The grooved portion 28 is formed by spinning a part of the cylindrical portion 20B to create a recess radially inward. On the other hand, the shoulder portion 29 is formed when the upper end of the cylindrical portion 20B is bent radially inward and crimped to the peripheral edge portion 31 of the sealing body 19, and extends radially inward. The sealing body 19 is fixed to the outer casing 20 by being sandwiched between the shoulder portion 29 and the grooved portion 28 via the gasket 24 through crimping. More specifically, the outer peripheral edge of the sealing plate 22 of the sealing body 19 (the annular portion outside the thickened portion 35, which will be described later) is sandwiched between the shoulder portion 29 and the grooved portion 28 via a gasket 24 and fixed to the outer can 20.

[0025] The sealing body 19 has a structure in which a metal terminal plate 21, an annular insulating plate 23, and a metal sealing plate 22 are stacked in order from the electrode body 14 side. The sealing plate 22 is a rupture plate (valve body) and is positioned opposite the terminal plate 21 with the insulating plate 23 in between. The insulating plate 23 has an opening 23A formed in the radial center and a ventilation hole 23B provided in the part that overlaps with the ventilation hole 21C of the terminal plate 21. The sealing plate 22 has a valve portion 22A on the radial center side that ruptures as the internal pressure of the battery rises. The terminal plate 21 has an annular portion 21A and a central portion 21B that is connected to the radially inward end of the annular portion 21A and is located in the radial center. The central portion 21B has a disc shape and is thinner than the annular portion 21A.

[0026] The valve portion 22A is joined to the central portion 21B of the terminal plate 21 by welding or the like through an opening 23A in the insulating plate 23. The valve portion 22A includes a projection 33 located in the radial center and projecting downward, and a thin-walled portion 34 located radially outside the projection 33. The thickness of the thin-walled portion 34 decreases as it extends radially outward. Because the thickness of the thin-walled portion 34 decreases as it extends radially outward, an annular space 39 is provided below the thin-walled portion 34. The insulating plate 23 is positioned radially outside the projection 33 so as to surround the projection 33 around its entire circumference. The majority of the insulating plate 23 is located between the sealing plate 22 and the terminal plate 21.

[0027] The sealing plate 22 holds the insulating plate 23, and the insulating plate 23 holds the terminal plate 21. Specifically, the sealing plate 22 includes an annular thickened portion 35 connected to the radially outward end of the thinned portion 34, and the thickened portion 35 has an annular projection 37 that protrudes downward. The outer circumferential surface of the insulating plate 23 is fitted and fixed to the inner circumferential surface of the annular projection 37. The insulating plate 23 also has an annular projection 38 that protrudes downward on the outer circumferential side, and the inner circumferential surface of the annular projection 38 is fitted and fixed to the outer circumferential surface of the terminal plate 21. The insulating plate 23 includes a clamping portion 43 that is sandwiched radially between the annular projection 37 and the terminal plate 21. The ventilation hole 21C is provided in the annular portion 21A. The positive lead 17 is joined to the lower surface of the annular portion 21A. The terminal board 21 to which the positive lead 17 is connected and the sealing plate 22 are electrically connected, thereby forming a current path from the electrode body 14 to the sealing plate 22.

[0028] Figure 2 is a schematic diagram showing the area around the positive electrode lead bonding portion of the positive electrode 11 in a strip-shaped configuration, and a part of the positive electrode lead 17. In Figure 2, the shaded area is the region of the positive electrode core 45 where the positive electrode mixture layer 46 is located. As shown in Figure 2, the positive electrode 11 has a positive electrode core exposed portion 47 where the positive electrode core 45 is exposed, and the positive electrode lead 17 is bonded to the positive electrode core exposed portion 47 by, for example, ultrasonic welding.

[0029] The positive electrode lead 17 is joined to the positive electrode core exposed portion 47, which may be provided on the outer surface of the winding of the positive electrode 11 or on the inner surface of the winding of the positive electrode 11. In the example shown in Figure 2, to prevent short circuits of the positive electrode lead 17, an insulating tape 51 is attached to a part of the positive electrode lead 17 so as to surround its entire circumference. In addition, an insulating tape 52 is fixed to a region including a part of the positive electrode mixture layer 46 on both sides in the longitudinal direction of the positive electrode so as to cover all the contact portions of the positive electrode lead 17 that are in contact with the positive electrode core exposed portion 47. The insulating tapes 51 and 52 are made of insulating materials, for example, a polyimide film as the base material and silicone as the adhesive.

[0030] As shown in Figure 1, the insulating tape 51 covers the entire circumference of the portion of the positive electrode lead 17 that extends from the point where it protrudes from the electrode body 14 to a point beyond the center of the extending direction of the positive electrode lead 17. As shown in Figure 2, the positive electrode lead 17 has a small cross-sectional area 55 outside the electrode body 14. The entire circumference of the small cross-sectional area 55 is covered by the insulating tape 51. The small cross-sectional area 55 is the portion of the positive electrode lead 17 that has a notch 56. In the example shown in Figure 2, the small cross-sectional area 55 has a pair of notches 56 facing each other in the width direction of the positive electrode lead, but the small cross-sectional area may have only one notch. Also, in the example shown in Figure 2, the shape of the notch 56 is approximately semicircular, but the shape of the notch can be any shape, for example, rectangular, isosceles trapezoidal, triangular, semi-elliptical, etc.

[0031] In Figure 1, the area of ​​the positive electrode lead 17 that is filled in black is the small cross-sectional area 55. When L is defined as the radial length from the central axis of the outer can 20 to the innermost diameter point on the inner circumference of the outer can 20, and the area where the radial distance from the central axis is L / 2 or less is defined as the radial center, the insulating tape 51 includes the portion located in the radial center, and the small cross-sectional area 55 is provided in the radial center.

[0032] The sealing body 19 is equipped with a current interruption mechanism. Specifically, in the above configuration, when the battery 10 overheats abnormally and the internal pressure of the battery rises, the valve portion 22A inverts so that it becomes convex axially upward, using the radially outward annular end 22B, which has low rigidity in the thin-walled portion 34, as a fulcrum. Simultaneously with this inversion, the central portion 21B is separated from the annular portion 21A or detaches from the valve portion 22A. Since the valve portion 22A is insulated from the annular portion 21A by the insulating plate 23, the current path is interrupted by this inversion. This interruption suppresses the overheating of the battery 10. If the internal pressure of the battery rises further, the annular end 22B of the thin-walled portion 34 breaks, forming a gas outlet. As a result, high-temperature gas and molten material are discharged to the outside of the battery 10, and the battery 10 becomes safe.

[0033] Furthermore, the small cross-sectional region 55 not only has low strength due to its small cross-sectional area, but also high electrical resistance due to its small cross-sectional area, making it prone to generating large amounts of Joule heat and becoming hot. Therefore, even if the current path is not properly interrupted when the battery 10 overheats abnormally, the small cross-sectional region 55 is easily cut by melting due to Joule heat. Thus, even in such cases, it becomes easier to properly interrupt the current, thereby increasing the safety of the battery 10.

[0034] As in this embodiment, when the small cross-sectional region 55 is covered with insulating tape 51, the Joule heat generated in the small cross-sectional region 55 becomes trapped inside the insulating tape 51 and is less likely to be dissipated to the outside, so the small cross-sectional region 55 can be effectively cut off when the battery 10 overheats abnormally. Also, when the battery 10 overheats abnormally, the sealing body 19 and the positive electrode core 45 tend to function as heat sinks. Therefore, heat from both ends in the extending direction of the positive electrode lead 17 is easily transferred to the sealing body 19 and the positive electrode core 45, while heat from the central part in the extending direction of the positive electrode lead 17 is less likely to be dissipated and tends to be trapped inside the positive electrode lead 17. Thus, by providing the small cross-sectional region 55 in the radial center, the small cross-sectional region 55 can be effectively cut off when the battery 10 overheats abnormally.

[0035] As in this embodiment, by using insulating tape 51, which has insulating properties to suppress short circuits of the positive lead 17, to cover the small cross-sectional area 55, the number of parts can be reduced. However, a tape other than the insulating tape for suppressing short circuits of the positive lead may be fixed to the small cross-sectional area so as to cover the entire circumference of the small cross-sectional area. In this case, if the tape is an insulating tape with excellent heat insulation properties, it is preferable as it can further suppress heat dissipation from the small cross-sectional area when the battery overheats abnormally.

[0036] As the insulating tape, for example, insulating tape containing ceramic fibers, insulating tape containing a material in which aluminum has been vapor-deposited onto glass cloth, insulating tape containing glass cloth made by laminating glass cloth onto aluminum foil and further applying a synthetic resin adhesive, insulating tape containing foamed material made by insulating tape containing foamed polyethylene, insulating tape containing a material made by applying an acrylic adhesive to aluminum foil, or insulating tape containing silicone rubber may be used. Alternatively, the insulating tape may contain an insulating material used for insulating purposes and a fixing agent for fixing the insulating material to the positive electrode lead, and the fixing agent may be an adhesive made of glue or paste.

[0037] Referring to Figure 2, it is preferable that the insulating tape 51 covering the small cross-sectional area 55 is a tape with higher thermal insulation properties than the insulating tape 52. For example, it is preferable that the insulating tape 51 is made of a material with higher thermal insulation properties than the insulating tape 52, or that it is thicker. Since the insulating tape 52 is wound, it is desirable that it be thin and highly flexible, which limits the material and thickness, but since a large portion of the insulating tape 51 is located outside the electrode body 14, it is possible to prioritize thermal insulation in its design.

[0038] When the battery 10 overheats abnormally, the small cross-sectional area 55 is more likely to be cut, so it is preferable that the small cross-sectional area 55 is located in a region of L / 3 or less from the central axis while being covered by tape around its entire circumference. Also, when the battery 10 overheats abnormally, high-temperature gas is more likely to flow inside the hollow portion 14A (see Figure 1) of the electrode body 14. Therefore, when the battery 10 overheats abnormally, high-temperature gas is more likely to come into contact with the small cross-sectional area 55, making it more likely to be cut, so it is preferable that at least a part of the small cross-sectional area 55 is positioned so as to overlap the hollow portion 14A in the axial direction.

[0039] This disclosure is not limited to the embodiments and their modifications, and various improvements and modifications are possible within the scope of the claims of this application and their equivalents. For example, the small cross-sectional area does not have to be covered with tape. Also, the small cross-sectional area may be provided at a location other than the radial center.

[0040] The case described above is when the small cross-sectional region 55 is the extended portion of the positive electrode lead 17 in which a notch 56 is provided. However, the small cross-sectional region can be any region of the electrode lead with a small cross-sectional area in a section perpendicular to the extension direction. For example, as shown in Figure 3, the small cross-sectional region 155 may be the extended portion of the positive electrode lead 117 in which a through hole 156 is provided. The small cross-sectional region may also include an extended portion in which both a part of the notch and a part of the through hole exist. Furthermore, multiple small cross-sectional regions may be provided at intervals in the extension direction of the positive electrode lead. For example, the positive electrode lead may have a first extended portion in which a notch is provided, and a second extended portion that is spaced apart from the first extended portion and has a through hole.

[0041] The case described above includes a terminal plate 21, a sealing plate (rupture plate) 22, and an insulating plate 23 located between them. However, the sealing body may have a laminated structure including two rupture plates (lower valve body and upper valve body), and may further include a convex terminal cap covering the two rupture plates. Alternatively, the sealing body may consist only of rupture plates. Or, the sealing body may not have rupture plates, and the bottom of the outer casing may have a thin, easily breakable section that breaks when the battery overheats abnormally. In these cases as well, the battery of this disclosure can be made more safe because the positive electrode lead is more likely to break when the battery overheats abnormally.

[0042] The case described above involves a positive electrode lead 17 including a small cross-sectional region 55 being joined to a positive electrode core exposed portion 47 that extends from one end to the other in the positive electrode width direction. However, as shown in Figure 4, the positive electrode lead 17 including the small cross-sectional region 55 may be joined to a positive electrode core exposed portion 247 that is located only in a part of the positive electrode width direction and overlaps the positive electrode mixture layer 246 of the positive electrode 211 in the positive electrode width direction. In this case, the area where the positive electrode mixture layer 246 is arranged can be increased, thereby increasing the battery capacity.

[0043] The case described above is one in which the positive electrode lead 17 is an electrode lead having a region with a smaller cross-sectional area, the positive electrode 11 is electrically connected to the sealing body 19, and the negative electrode 12 is electrically connected to the outer can 20. However, the negative electrode lead may also be an electrode lead having a region with a smaller cross-sectional area, and the negative electrode may be electrically connected to the sealing body, and the positive electrode may be electrically connected to the outer can.

[0044] Further, the cylindrical battery of the present disclosure may have the following configuration. Configuration 1: An electrode body in which a positive electrode and a negative electrode are wound via a separator, an electrode lead electrically connected to the electrode body, and an exterior can that houses the electrode body and the electrode lead, wherein the electrode lead has a small cross-section region with a small cross-sectional area outside the electrode body, a cylindrical battery. Configuration 2: The cylindrical battery according to Configuration 1, comprising a tape attached to the outer peripheral surface of the electrode lead, wherein the small cross-section region is covered with the tape. Configuration 3: The cylindrical battery according to Configuration 2, wherein the tape has insulating properties and can suppress a short circuit of the electrode lead. Configuration 4: The cylindrical battery according to any one of Configurations 1 to 3, wherein the small cross-section region includes an extending portion provided with a notch in the electrode lead. Configuration 5: The cylindrical battery according to any one of Configurations 1 to 5, wherein the small cross-section region includes an extending portion provided with a through-hole in the electrode lead. Configuration 6: The cylindrical battery according to Configuration 2 or 3, wherein the tape includes a portion located at the central portion in the radial direction. Configuration 7: The cylindrical battery according to any one of Configurations 1 to 6, wherein the small cross-section region is provided at the central portion in the radial direction.

[0045] 10 Battery, 11, 211 Positive electrode, 12 Negative electrode, 13 Separator, 14 Electrode body, 14A Hollow portion, 15 Upper insulating plate, 16 Lower insulating plate, 17, 117 Positive electrode lead, 18 Negative electrode lead, 19 Sealing body, 20 Exterior can, 20A Bottom, 20B Cylindrical portion, 21 Terminal plate, 21A Annular portion, 21B Central portion, 21C Vent hole, 22 Sealing plate, 22A Valve portion, 22B Annular end portion, 23 Insulating plate, 23A Opening portion, 23B Vent hole, 24 Gasket, 28 Groove portion, 29 Shoulder portion, 31 Peripheral portion, 33 Protrusion portion, 34 Thin-walled portion, 35 Thick-walled portion, 37, 38 Annular protrusion portion, 39 Space, 43 Clamping portion, 45 Positive electrode core, 46, 246 Positive electrode mixture layer, 47, 247 Positive electrode core exposed portion, 51, 52 Insulating tape, 55, 155 Small cross-section region, 56 Notch, 156 Through-hole.

Claims

1. A cylindrical battery comprising: an electrode body in which a positive electrode and a negative electrode are wound with a separator between them; electrode leads electrically connected to the electrode body; and an outer casing housing the electrode body and the electrode leads, wherein the electrode leads have a small cross-sectional area on the outside of the electrode body.

2. The cylindrical battery according to claim 1, comprising a tape attached to the outer circumferential surface of the electrode lead, wherein the small cross-sectional area is covered with the tape.

3. The cylindrical battery according to claim 2, wherein the tape has insulating properties and can suppress short circuits of the electrode leads.

4. The cylindrical battery according to any one of claims 1 to 3, wherein the small cross-sectional region includes an extended portion of the electrode lead in which a notch is provided.

5. The cylindrical battery according to any one of claims 1 to 3, wherein the small cross-sectional region includes an extended portion in the electrode lead where a through hole is provided.

6. The cylindrical battery according to claim 2 or 3, wherein the tape includes a portion located in the radial center.

7. The cylindrical battery according to claim 1, wherein the small cross-sectional area is provided in the central part in the radial direction.

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