Cylindrical battery

Abstract

A battery (10) is provided with: an electrode body (14) in which a positive electrode and a negative electrode are wound with a separator interposed therebetween; a positive electrode lead (17) that is electrically connected to a positive electrode (11); a sealing body (19) that is electrically connected to the positive electrode lead (17); an outer can (20) that accommodates the electrode body (14) and the positive electrode lead (17); and a heat insulating tape (55) that covers at least a portion of the positive electrode lead (17) located outside the electrode body (14) over the entire circumference. The heat-insulating tape (55) is preferably positioned at a distance from the electrode body (14).

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 via a separator, 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 via a gasket. The positive electrode is electrically connected to the sealing body, and the negative electrode is electrically connected to the outer can. Such a cylindrical battery may be provided with a current interruption mechanism. In the current interruption mechanism, for example, when the internal pressure of the cylindrical battery rises during abnormal heat generation, the sealing body is deformed and the terminal plate inside the outer can is broken, thereby interrupting the current to the sealing body.

[0003] Japanese Patent Application Laid-Open No. 2016-225014

[0004] In recent years, in view of various worst-case scenarios, it has been required to enhance safety. For example, even if the current interruption mechanism as described above does not operate properly due to some problems, if the current to the sealing body can be interrupted, high safety can be ensured. Also, regardless of the presence or absence of the current interruption mechanism as described above, if the current to the sealing body can be interrupted when the internal pressure of the battery rises, high safety can be ensured. 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 first electrode and a second electrode are wound via a separator, an electrode lead electrically connected to the first electrode, a sealing body electrically connected to the electrode lead, an outer can that houses the electrode body and the electrode lead, and a heat insulating material that covers at least a portion of the electrode lead located outside the electrode body over the entire circumference.

[0006] According to the cylindrical battery of 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 an enlarged cross-sectional view of the area around the sealing body in the cylindrical battery. This is an enlarged cross-sectional view of the cylindrical battery of the first modified example corresponding to Figure 2. This is an enlarged cross-sectional view of the cylindrical battery of the second modified example corresponding to Figure 2. This is a schematic diagram showing the area around the positive electrode lead connection portion and a part of the positive electrode in the strip-shaped positive electrode 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 connection portion and a part of the positive electrode in the strip-shaped positive electrode of a 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 as an example of a first electrode, a long negative electrode 12 as an example of a second electrode, 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 and a positive electrode mixture layer formed on both sides of the positive electrode core. The positive electrode core can be made of a metal foil that is stable within 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 layer contains 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, drying the coating, and then compressing it to form the positive electrode mixture layer on both sides of the positive electrode core.

[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 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 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 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, a 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. The positive electrode lead 17 is an example of an electrode lead electrically connected to the first electrode. On the other hand, a negative electrode lead 18 attached to the negative electrode 12 extends through the outside of the lower insulating plate 16 towards the bottom 20A of the outer container 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 container 20 to which the negative electrode lead 18 is connected becomes the negative electrode terminal.

[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 increases. The terminal plate 21 has an annular portion 21A and a central portion 21B that is connected to the radially inward annular 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 an enlarged cross-sectional view of the area around the sealing body 17 in the battery 10. The positive electrode 11 has a positive electrode core exposed portion 47 (see Figure 5) in which the positive electrode core is exposed because the positive electrode mixture layer is not arranged in a part of the longitudinal direction of the positive electrode, and the positive electrode lead 17 is joined to the positive electrode core exposed portion 47 by, for example, ultrasonic welding. The positive electrode core exposed portion 47 to which the positive electrode lead 17 is joined 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.

[0029] Figure 5 is a schematic diagram showing the area around the positive electrode lead connection portion of the positive electrode 11 in the strip-shaped unfolded positive electrode of the battery 10, and a part of the positive electrode lead 17. As shown in Figures 1, 2, and 5, in order to prevent short circuits of the positive electrode lead 17, an insulating tape 51 having insulating properties is attached to a part of the positive electrode lead 17 so as to surround the entire circumference of the positive electrode lead 17. In the example shown in Figure 2, the insulating tape 51 covers the entire circumference of the positive electrode lead 17 from a first position P1 (see Figures 2 and 5) that overlaps the positive electrode 11 in the positive electrode thickness direction, through a through hole in the upper insulating plate 15, and bends to a second position P2 (see Figures 2 and 5) that overlaps the upper insulating plate 15 axially on the upper side of the upper insulating plate 15.

[0030] The battery 10 may have an insulating tape 52 (see Figures 2 and 5) different from the insulating tape 51, which covers all contact portions of the positive electrode lead 17 that are in contact with the positive electrode core exposed portion 47. The insulating tape 51 and insulating tape 52 are made of an insulating material, for example, a polyimide film as the base material and silicone as the adhesive.

[0031] The battery 10 further includes an insulating tape 55 as an example of an insulating material. The insulating tape 55 is arranged at intervals on the insulating tape 51 and covers the entire circumference of the portion of the positive electrode lead 17 that is located closer to the terminal board 21 than the portion covered by the insulating tape 51. The insulating tape 55 may contain any material used as an insulating material. Examples of insulating tape 55 include 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 composed of aluminum foil laminated with glass cloth and further coated with a synthetic resin adhesive, insulating tape containing foamed material composed of insulating tape containing foamed polyethylene, insulating tape containing a material in which an acrylic adhesive has been applied to aluminum foil, or insulating tape containing silicone rubber. Alternatively, the insulating tape 55 may include 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, glue, or the like.

[0032] Referring to Figure 1, 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 battery 10 includes a covering portion 17a (see Figures 1 and 5) in which the positive electrode lead 17 is covered with an insulating tape 55 that has excellent heat insulation properties. Therefore, even if the current path is not properly interrupted when the battery 10 overheats abnormally, the Joule heat generated in the covering portion 17a and the Joule heat transferred from the part of the positive electrode lead 17 other than the covering portion to the covering portion 17a tend to accumulate inside the insulating tape 55, making the covering portion 17a more likely to melt and break. Thus, even in such cases, it becomes easier to properly interrupt the current, thereby increasing the safety of the battery 10.

[0034] Making the thickness of the heat-insulating tape 55 thicker than that of the insulating tape 51 suppresses heat dissipation from the covering portion 17a to the outside, so that the covering portion can be effectively cut when the battery 10 overheats abnormally. Also, when the battery 10 overheats abnormally, the sealing body 19 and the positive electrode core easily 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, while heat from the central part in the extending direction of the positive electrode lead 17 is difficult to dissipate and tends to accumulate inside the positive electrode lead 17.

[0035] Therefore, with respect to the extending direction of the positive electrode lead 17, if the center position P5 (see Figure 1) between the point where the positive electrode lead 17 protrudes from the positive electrode 11 P3 (see Figures 1 and 5) and the position P4 (see Figure 1) of the end of the positive electrode lead 17 on the protruding point P3 side at the joint 90 of the positive electrode lead 17 with respect to the sealing body 19 is included in the covering portion 17a, then the covering portion 17a can be effectively cut off when the battery 10 overheats abnormally.

[0036] Since the roundness of the electrode body 14 tends to be higher, and battery performance and reliability tend to be higher, it is preferable that the heat insulating tape 55 be located outside the electrode body 14, and preferably at a distance from the electrode body 14. Also, as shown in Figure 2, the positive electrode lead 17 has a joint portion 90 joined to the sealing body 19, more specifically to the terminal plate 21, and a folded portion 91 located on the electrode body 14 side of the joint portion 90 and folded back radially inward. Since the folded portion 91 is easy to bend and the battery 10 is easy to manufacture, it is preferable that the heat insulating tape 55 covers only the lead portion 17b (see Figures 1 and 5) of the positive electrode lead 17 that is located on the electrode body 14 side of the folded portion 91.

[0037] This disclosure is not limited to the above embodiments and their variations, and various improvements and modifications are possible within the scope of the claims of this application and their equivalents. For example, in the above embodiments, the heat insulating tape 55 was spaced apart from the insulating tape 51. However, the battery of this disclosure may also include a heat insulating material covering the entire circumference of at least the portion of the positive electrode lead that is located outside the electrode body, and an insulating tape that covers the entire circumference of at least the extension portion of the positive electrode lead that extends from the positive electrode and also has insulating properties, and at least a portion of the heat insulating material may be provided so as to overlap the insulating tape.

[0038] In this case, at least a portion of the insulating material may be located inside or outside the insulating tape. According to this modified example, the heat dissipation of the portion of the positive electrode lead covered by both the insulating tape and the insulating material can be effectively suppressed. Therefore, when the battery overheats abnormally, that portion can be effectively cut off, thereby increasing the safety of the battery. The overlapping portion of the insulating tape and the insulating material can be easily formed, for example, by fixing the insulating material to the insulating tape so that it is wrapped around the entire circumference of the insulating tape from the outside of the insulating tape covering the positive electrode lead.

[0039] When the battery overheats abnormally, the overlapping portion of the insulating tape and the insulating material makes it easier to cut the positive electrode lead portion covered by it. Therefore, it is preferable that the overlapping portion covers the center position P5 (see Figure 1) between the protruding position P3 (see Figure 1) of the positive electrode lead and the position P4 (see Figure 1) of the end of the positive electrode lead on the protruding position P3 side at the joint of the positive electrode lead to the sealing body.

[0040] Figure 3 is an enlarged cross-sectional view corresponding to Figure 2 of the battery 110 of the first modified example. As shown in Figure 3, in comparison with the above embodiment, the length of the portion of the insulating tape 151 covering the positive electrode lead 17 in the above embodiment may be increased without using the insulating tape 55. In other words, the insulating tape 151 may constitute the insulating material.

[0041] More specifically, the insulating tape 151 may cover the positive electrode lead 17 from the point where it protrudes from the positive electrode 11 (P3) to the center position P5 between the end of the joint 90 of the positive electrode lead 17 with respect to the sealing body 19 on the protruding point P3 side. According to this modified example, the insulating tape 151, which has insulating properties to suppress short circuits of the positive electrode lead 17, can be used to cut the positive electrode lead 17 in the event of abnormal overheating of the battery 110, thereby reducing the number of parts. As shown in Figure 4, the insulating tape 251 used to cut the positive electrode lead 17 in the event of abnormal overheating of the battery 210 may extend from a position spaced apart from the positive electrode 11 towards the sealing body 19. In this case, the insulating tape 251 may cover the positive electrode lead from the point where it protrudes from the electrode body 14 to the center position between the end of the joint 90 of the positive electrode lead with respect to the sealing body on the protruding point side.

[0042] 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.

[0043] The case described above is one in which the positive electrode lead 17 is an electrode lead electrically connected to the sealing body 19, 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 electrically connected to the sealing body, and the negative electrode may be electrically connected to the sealing body and the positive electrode may be electrically connected to the outer can. Furthermore, the insulating material covering the entire circumference of at least the portion of the electrode lead located outside the electrode body may be composed of an insulating substance applied to the positive electrode lead. Also, in this embodiment, as shown in Figure 5, the insulating tape 52 covers the exposed portion 47 of the positive electrode core up to a certain point in the axial direction, but as shown in Figure 6, it may cover up to the lower end of the exposed portion 47 of the positive electrode core.

[0044] Further, the cylindrical battery of the present disclosure may have the following configuration. Configuration 1: An electrode body in which a first electrode and a second electrode are wound via a separator, an electrode lead electrically connected to the first electrode, a sealing body electrically connected to the electrode lead, an exterior can housing the electrode body and the electrode lead, and a heat insulating material covering at least a portion of the electrode lead located outside the electrode body over the entire circumference. A cylindrical battery. Configuration 2: The cylindrical battery according to Configuration 1, wherein the heat insulating material covers a central position between a position where the electrode lead protrudes from the first electrode and a position of an end on the protruding position side at a joint of the electrode lead to the sealing body with respect to the extending direction of the electrode lead. Configuration 3: The cylindrical battery according to Configuration 2, wherein the heat insulating material covers from the protruding position to the central position in the electrode lead. Configuration 4: An insulating tape different from the heat insulating material is provided, and the insulating tape covers at least an extending portion of the electrode lead extending from the first electrode over the entire circumference. The cylindrical battery according to any one of Configurations 1 to 3. Configuration 5: The cylindrical battery according to Configuration 4, wherein at least a part of the heat insulating material is provided so as to overlap the insulating tape. Configuration 6: The cylindrical battery according to Configuration 4 or 5, wherein at least a part of the heat insulating material is provided so as to overlap the insulating tape. Configuration 7: The cylindrical battery according to any one of Configurations 1 to 6, wherein the heat insulating material is positioned at a distance from the electrode body. Configuration 8: The electrode lead has a joint portion joined to the sealing body and a folded-back portion located closer to the electrode body side than the joint portion and folded back inward in the radial direction, and the heat insulating material covers a lead portion of the electrode lead located closer to the electrode body side than the folded-back portion. The cylindrical battery according to any one of Configurations 1 to 7.

[0045] 10,110,210 Battery, 11 Positive electrode, 12 Negative electrode, 13 Separator, 14 Electrode body, 14A Hollow part, 15 Upper insulating plate, 16 Lower insulating plate, 17 Positive electrode lead, 17a Covering part, 17b Lead part, 18 Negative electrode lead, 19 Sealing body, 20 Outer can, 20A Bottom part, 20B Cylindrical part, 21 Terminal plate, 21A Annular part, 21B Central part, 21C Ventilation hole, 22 Sealing plate, 22A Valve part, 22B Annular end, 23 Insulating plate, 23A Opening, 23B Ventilation hole, 24 Gasket, 28 Grooved part, 29 Shoulder part, 31 Peripheral part, 33 P1 is the first position, P2 is the second position, P3 is the position where the positive lead protrudes from the positive electrode, P4 is the position of the end on the side where the positive lead protrudes from the positive electrode at the joint, and P5 is the center position of P4 and P5.

Claims

1. A cylindrical battery comprising: an electrode body in which a first electrode and a second electrode are wound with a separator between them; an electrode lead electrically connected to the first electrode; a sealing body electrically connected to the electrode lead; an outer casing housing the electrode body and the electrode lead; and a heat insulating material covering at least the portion of the electrode lead located outside the electrode body over its entire circumference.

2. The cylindrical battery according to claim 1, wherein the insulating material covers the center position between the position where the electrode lead protrudes from the first electrode and the position of the end on the protruding position side at the joint of the electrode lead with respect to the sealing body, with respect to the extending direction of the electrode lead.

3. The cylindrical battery according to claim 2, wherein the insulating material covers the electrode lead from the protruding position to the center position.

4. The cylindrical battery according to any one of claims 1 to 3, comprising an insulating tape different from the heat insulating material, wherein the insulating tape covers at least the extension portion of the electrode lead that extends from the first electrode over its entire circumference.

5. The cylindrical battery according to claim 4, wherein at least a portion of the heat insulating material is provided so as to overlap the insulating tape.

6. The cylindrical battery according to claim 4, wherein the heat insulating material is thicker than the insulating tape.

7. The cylindrical battery according to any one of claims 1 to 3, wherein the insulating material is positioned at a distance from the electrode body.

8. The cylindrical battery according to any one of claims 1 to 3, wherein the electrode lead has a joint portion joined to the sealing body and a folded portion located on the electrode body side of the joint portion and folded radially inward, and the insulating material covers the lead portion of the electrode lead located on the electrode body side of the folded portion.

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