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) therebetween; an external can (20) which accommodates the electrode body (14); and a sealing body (19) which closes an opening of the external can (20). The sealing body (19) has: a sealing plate (22) which has an annular protruding part (34) that protrudes to the electrode body (14) side in the axial direction; a terminal plate (21) to which is joined a positive electrode lead (17) that extends from the electrode body (14); and an annular insulating plate (23) which has an outer peripheral surface (40) that is internally fitted and fixed to an inner peripheral surface of the annular protruding part (34) and an inner peripheral surface (60) that is externally fitted and fixed to an outer peripheral surface of the terminal plate (21). At least one recess that is recessed in the radial direction is provided to at least of the outer peripheral surface (40) and the inner peripheral surface (60).

Description

Cylindrical battery

[0001] The present disclosure relates to cylindrical batteries.

[0002] A conventional cylindrical battery is described in Patent Document 1. This cylindrical battery includes an electrode assembly, a cylindrical outer can with a bottom that houses the electrode assembly, and a sealing body that closes the opening of the outer can via a gasket. The cylindrical portion of the outer can has a grooved portion and an annular shoulder portion. The grooved portion is formed by recessing a portion of the cylindrical portion radially inward. The shoulder portion is formed when the end of the opening side of the cylindrical portion is bent inward and crimped onto the peripheral edge of the sealing body, and extends radially inward.

[0003] The sealing body is fixed to the outer can by being crimped between the shoulder and groove with a gasket interposed between them. The sealing body includes a sealing plate that constitutes the electrode terminal and breaks when the internal pressure of the cylindrical battery becomes excessive, and an annular insulating plate. The insulating plate is fitted and fixed to the inner circumferential surface of the annular protrusion of the sealing plate. The insulating plate is provided to reliably interrupt the current path between the terminal plate and the sealing plate in the event that the sealing plate is reversed and breaks at the thin-walled portion.

[0004] Japanese Patent Application Publication No. 9-320562

[0005] The present inventors have discovered that when the sealing body of a cylindrical battery has a sealing plate with an annular protrusion that protrudes axially toward the electrode body, a terminal plate to which an electrode lead extending from the electrode body is joined, and an annular insulating plate having an outer peripheral surface that is fitted and fixed to the inner peripheral surface of the annular protrusion and an inner peripheral surface that is fitted and fixed to the outer peripheral surface of the terminal plate, the insulating plate needs to have a high fitting strength.

[0006] Specifically, the present inventors discovered that in a cylindrical battery equipped with such a sealing body, the insulating plate is sandwiched between the sealing plate and the terminal plate, and therefore when the insulating plate is crimped to the annular protrusion of the sealing plate, the insulating plate is susceptible to large radial crimping forces from both the outer and inner radial directions, making it necessary for the insulating plate to have high fitting strength. Therefore, an object of the present disclosure is to provide a cylindrical battery that can reduce the radial load applied to the insulating plate and improve the fitting strength of the insulating plate.

[0007] In order to solve the above problems, the cylindrical battery of the present disclosure comprises an electrode assembly in which a positive electrode and a negative electrode are wound with a separator interposed therebetween, an outer can that houses the electrode assembly, and a sealing body that closes the opening of the outer can, wherein the sealing body has a sealing plate with an annular protrusion that protrudes axially toward the electrode assembly, a terminal plate to which an electrode lead extending from the electrode assembly is joined, and an annular insulating plate having an outer peripheral surface that is fitted and fixed to the inner peripheral surface of the annular protrusion and an inner peripheral surface that is fitted and fixed to the outer peripheral surface of the terminal plate, and at least one of the outer peripheral surface and the inner peripheral surface is provided with one or more radially recessed depressions.

[0008] According to the cylindrical battery according to the present disclosure, the radial load on the insulating plate can be reduced, and the fitting strength durability of the insulating plate can be improved.

[0009] Fig. 2 is an axial cross-sectional view of a cylindrical battery according to an embodiment of the present disclosure; Fig. 3 is a top view of an insulating plate as viewed from above in the axial direction; Fig. 4 is a top view of an insulating plate of a reference example corresponding to Fig. 2; Fig. 5 is a top view of an insulating plate of a first modified example corresponding to Fig. 2; Fig. 6 is a top view of an insulating plate of an insulating plate of a second modified example corresponding to Fig. 2; Fig. 7 is a top view of an insulating plate of a third modified example corresponding to Fig. 2;

[0010] Hereinafter, an embodiment of a cylindrical battery according to the present disclosure will be described in detail with reference to the drawings. The cylindrical battery according to the present disclosure may be a primary battery or a secondary battery. It may also be a battery using an aqueous electrolyte or a battery using a non-aqueous electrolyte. Hereinafter, a lithium-ion secondary battery 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.

[0011] It is anticipated from the beginning that new embodiments will be constructed by appropriately combining the features of the embodiments and variations described below. In the following embodiments, the same components are designated by the same reference numerals in the drawings, and redundant descriptions will be omitted. Furthermore, multiple drawings include schematic diagrams, and the dimensional ratios of the length, width, height, and other dimensions of each component do not necessarily match between different drawings. In this specification, the sealing body 19 side in the axial direction (height direction) of the cylindrical battery 10 is referred to as "upper," and the bottom 20A side of the outer can 20 in the axial direction is referred to as "lower." In the following description, when referring to the outer peripheral surface of the insulating plate, this outer peripheral surface refers to the outer peripheral surface that is fitted and fixed to the inner peripheral surface of the annular protrusion of the sealing plate. When referring to the inner peripheral surface of the insulating plate, this inner peripheral surface refers to the inner peripheral surface that is fitted and fixed to the outer peripheral surface of the terminal plate. Among the components described below, components not recited in the independent claims representing the highest concept are optional components and are not required components. Furthermore, units are not specified in this specification (the following description). The MKS unit system can be used as units.

[0012] Fig. 1 is an axial cross-sectional view of a cylindrical battery 10 according to one embodiment of the present disclosure. As shown in Fig. 1, the cylindrical battery (hereinafter simply referred to as battery) 10 includes an electrode assembly 14, a non-aqueous electrolyte, a cylindrical outer can 20 with a bottom that houses the electrode assembly 14 and the non-aqueous electrolyte, and a sealing body 19 that closes the opening of the outer can 20 via an annular gasket 24.

[0013] The electrode assembly 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 with the separators 13 interposed therebetween. The negative electrode 12 is formed to be slightly larger 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 the axial direction. The two separators 13 are formed to be slightly larger 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.

[0014] The non-aqueous electrolyte has ion conductivity (e.g., lithium ion conductivity). The non-aqueous electrolyte may be a liquid electrolyte (electrolytic solution) or a solid electrolyte. The liquid electrolyte (electrolytic solution) 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 mixed solvents of two or more of these. Examples of the non-aqueous solvent include ethylene carbonate (EC), ethyl methyl carbonate (EMC), dimethyl carbonate (DMC), diethyl carbonate (DEC), and mixed solvents of these. The non-aqueous solvent may contain a halogen-substituted compound (e.g., fluoroethylene carbonate) in which at least a portion of the hydrogen atoms of these solvents are substituted with halogen atoms such as fluorine. The electrolyte salt may include, for example, LiPF ６ Lithium salts such as

[0015] Examples of the solid electrolyte include solid or gel polymer electrolytes and inorganic solid electrolytes. The polymer electrolyte includes, for example, a lithium salt and a matrix polymer, or a non-aqueous solvent, a lithium salt, and a matrix polymer. Examples of the matrix polymer include a polymer material that absorbs the non-aqueous solvent and gels. Examples of the polymer material include fluororesin, acrylic resin, and polyether resin. Examples of the inorganic solid electrolyte include materials known in all-solid-state lithium ion secondary batteries (e.g., oxide-based solid electrolytes, sulfide-based solid electrolytes, halide-based solid electrolytes, etc.).

[0016] The positive electrode 11 has a positive electrode core and positive electrode mixture layers formed on both sides of the positive electrode core. The positive electrode core can be made of 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 is 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 core, drying the coating, and then compressing it to form positive electrode mixture layers on both sides of the positive electrode core.

[0017] 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.

[0018] Examples of conductive agents contained 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 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, polyethylene oxide (PEO), and the like.

[0019] The negative electrode 12 has 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, 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 is produced, for example, by applying a negative electrode mixture slurry containing the negative electrode active material and the binder onto the negative electrode core, drying the coating, and then compressing it to form a negative electrode mixture layer on both sides of the negative electrode core.

[0020] The negative electrode active material generally uses a carbon material that reversibly absorbs and releases lithium ions. Preferred carbon materials are graphites such as 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. In addition, the negative electrode active material may be a metal other than Si that alloys with lithium, an alloy containing such a metal, or a compound containing such a metal.

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

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

[0023] An upper insulating plate 15 is disposed above the electrode body 14, and a lower insulating plate 16 is disposed below the electrode body 14. In the example shown in FIG. 1 , a positive electrode lead 17 attached to the positive electrode 11 passes through a through-hole in the upper insulating plate 15, extends toward the sealing body 19, and is connected to the underside of the sealing body 19 by welding or the like. On the other hand, a negative electrode lead 18 attached to the negative electrode 12 passes outside the lower insulating plate 16, extends toward the bottom 20A of the outer can 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 serves as a positive electrode terminal, and the outer can 20 to which the negative electrode lead 18 is connected serves as a negative electrode terminal. Note that the negative electrode lead 18 may pass through a through-hole in the lower insulating plate 16 instead of passing outside the lower insulating plate 16.

[0024] A gasket 24 is provided between the outer can 20 and the sealing body 19 to ensure sealing of the battery interior and insulation between the outer can 20 and the sealing body 19. The outer can 20 has a cylindrical portion 20B and a bottom portion 20A. 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 portion of the cylindrical portion 20B to recess it radially inward. The shoulder portion 29, on the other hand, is formed when the upper end of the cylindrical portion 20B is bent radially inward and the peripheral edge portion 31 of the sealing body 19 is crimped, and extends radially inward. The sealing body 19 is clamped between the shoulder portion 29 and the grooved portion 28 via the gasket 24, and is fixed to the outer can 20.

[0025] The sealing body 19 is a disk-shaped integrated mechanism equipped with a current interruption mechanism. The sealing body 19 has a structure in which, in order from the electrode body 14 side, a terminal plate 21, an insulating plate 23, and a sealing plate 22 are stacked. The sealing plate 22 tightly seals the opening of the outer can 20 via a gasket 24, and is disposed opposite the terminal plate 21 with the insulating plate 23 sandwiched between them. The insulating plate 23 has an opening 23A formed in its radial center and one or more ventilation holes 23B formed therein that communicate with the ventilation hole 21C of the terminal plate 21.

[0026] Sealing plate 22 holds insulating plate 23, and insulating plate 23 holds terminal plate 21. More specifically, sealing plate 22 has an annular protrusion 34 that protrudes downward on its outer periphery, and an outer periphery surface 40 of insulating plate 23 is fitted and fixed to the inner periphery surface of annular protrusion 34. Insulating plate 23 also has an annular protrusion 35 that protrudes downward on its outer periphery, and an inner periphery surface 60 of annular protrusion 35 is fitted and fixed to the outer periphery surface of terminal plate 21. Insulating plate 23 is clamped radially between annular protrusion 34 and terminal plate 21.

[0027] The sealing plate 22 has a valve portion 22A at its radial center that ruptures when the battery internal pressure exceeds a predetermined threshold, and the valve portion 22A is connected by welding or the like to a central portion 21B of the terminal plate 21 through an opening 23A in the insulating plate 23. The valve portion 22A includes a lower protrusion 32A that protrudes toward the inside of the battery and is provided at the radial center, and a thin portion 32B formed around the lower protrusion 32A. The thickness of the thin portion 32B becomes thinner as it goes radially outward.

[0028] The terminal plate 21 is a metal plate and includes a thick annular portion 21A to which the positive electrode lead 17 is connected, and a disk-shaped central portion 21B that is connected to a radially inner end of the annular portion 21A and is thinner than the annular portion 21A. The positive electrode lead 17 constitutes an electrode lead that is joined to the terminal plate 21. An air vent 21C is formed in the annular portion 21A. The positive electrode lead 17 is connected to the underside of the annular portion 21A. The terminal plate 21 to which the positive electrode lead 17 is connected is electrically connected to the sealing plate 22, thereby forming a current path that connects the electrode body 14 to the sealing plate 22.

[0029] The electrode assembly accommodating chamber 20C below the grooved portion 28 in the outer can 20 communicates with the annular space 33 below the thin-walled portion 32B via the vent holes 21C and 23B. When the electrode assembly 14 generates abnormal heat, the air pressure in the annular space 33 communicating with the electrode assembly accommodating chamber 20C increases, causing the valve portion 22A to invert so as to become convex axially upward, with the annular end portion 22B as a fulcrum. Simultaneously with this inversion, the central portion 21B is separated from the annular portion 21A. Because the valve portion 22A is insulated from the annular portion 21A by the insulating plate 23, this inversion interrupts the current path. If the battery internal pressure further increases, the annular end portion 22B of the thin-walled portion 32B breaks, forming a gas outlet.

[0030] It is preferable that the terminal plate 21 has a plurality of vent holes 21C arranged at equal intervals in the circumferential direction, and the insulating plate 23 has a plurality of vent holes 23B arranged at equal intervals in the circumferential direction, so that when the electrode body 14 generates abnormal heat, gas can easily flow smoothly from the electrode body accommodating chamber 20C to the annular space 33, and the current interruption mechanism can easily operate appropriately.

[0031] 2 is a top view (plan view) of the insulating plate 23 as viewed from above in the axial direction (above in the thickness direction). As shown in Fig. 2, the outer peripheral surface 40 of the insulating plate 23 has one or more recesses 41 recessed in the radial direction, and in this embodiment, has a plurality of identical recesses 41. Among the plurality of recesses 41, two adjacent recesses 41 in the circumferential direction are continuously connected. In a cross section of the insulating plate 23 perpendicular to the axial direction and passing through the outer peripheral surface 40, the outer peripheral surface 40 has a wave shape with continuously repeated concave and convex portions.

[0032] Next, we will explain the problems discovered by the inventors and the effects of the cylindrical battery according to the present disclosure. When the sealing body of a cylindrical battery has a sealing plate with an annular protrusion that protrudes axially toward the electrode body, a terminal plate to which an electrode lead extending from the electrode body is joined, and an annular insulating plate with an outer circumferential surface that is fitted and fixed to the inner circumferential surface of the annular protrusion and an inner circumferential surface that is fitted and fixed to the outer circumferential surface of the terminal plate, the insulating plate is sandwiched between the sealing plate and the terminal plate.

[0033] Therefore, as shown in Figure 3, that is, the top view of insulating plate 423 of the reference example corresponding to Figure 2, if both outer peripheral surface 440 and inner peripheral surface 460 are circular in plan view, when the upper end of the tubular portion of the outer can is crimped to the peripheral edge of the sealing body, the insulating plate is likely to be subjected to large radial forces from both the outer and inner radial directions, and insulating plate 423 needs to have a high fitting strength and resistance.

[0034] In contrast, in the battery 10 of the above embodiment, one or more radially recessed depressions 41 are provided in the outer peripheral surface 40 of the insulating plate 23. This reduces the radially inward force that the insulating plate 23 receives from the sealing plate 22 when the upper end of the tubular portion 20B of the outer can 20 is crimped onto the peripheral edge 31 of the sealing body 19, and also reduces the radially inward force that the insulating plate 23 continues to receive from the sealing plate 22 after the battery is assembled. This reduces the radial load that the insulating plate 23 receives, and improves the fitting strength durability of the insulating plate 23.

[0035] As in the battery 10 of the above embodiment, when the outer surface 40 has a wavy shape with continuously repeated unevenness in a cross section perpendicular to the axial direction of the insulating plate 23, radial forces are more likely to be applied to the insulating plate 23 evenly in the circumferential direction, which makes it possible to prevent large radial loads from being applied to local circumferential positions of the insulating plate 23, and further increases the fitting strength resistance of the insulating plate 23.

[0036] The distance between the central axis P of the outer can 20 and the outer peripheral surface 40 in the radial direction (the radial direction of the battery 20 (which coincides with the radial direction of the outer can 20)) is defined as the radius of the outer peripheral surface 40. Furthermore, suppose that a recess 41 is provided on the outer peripheral surface 40, the maximum radius of the outer peripheral surface 40 is R1, the area of ​​a circle with radius R1 is S1, and the area of ​​a plane perpendicular to the axial direction and enclosed by the outer peripheral surface 40 is S2. In this case, in order to effectively improve the fitting strength durability of the insulating plate 23, it is preferable that S2 / S1 be 0.98 or less. Furthermore, since this effectively suppresses the relative movement of the insulating plate 23 with respect to the sealing plate 22, it is preferable that S2 / S1 be 0.94 or more. Note that, if the insulating plate 23 is movable in the radial direction relative to the outer can 20, the maximum radius of the outer peripheral surface 40 is defined as the maximum radius when the insulating plate 23 is positioned relative to the outer can 20 so that this maximum radius is maximized.

[0037] The present disclosure is not limited to the above-described embodiment and its modifications, and various improvements and modifications are possible within the scope of the claims of the present application and their equivalents. For example, in the above-described embodiment, one or more recesses are provided on the outer peripheral surface 40 of the insulating plate 23 that abuts on the inner peripheral surface of the annular protrusion 34 of the sealing plate 22. However, as shown in Figure 4, i.e., a top view of the insulating plate 123 of a first modification corresponding to Figure 2, in addition to providing one or more recesses 141 on the outer peripheral surface 140 that abuts on the inner peripheral surface of the annular protrusion 34 of the sealing plate 22, one or more recesses 142 may also be provided on the inner peripheral surface 160 that abuts on the outer peripheral surface of the terminal plate 21.

[0038] This reduces not only the radially inward force that insulating plate 123 receives from sealing plate 22, but also the radially outward force that insulating plate 123 receives from terminal plate 21. Therefore, the radial load that insulating plate 123 receives can be more effectively reduced, and the fitting strength durability of insulating plate 123 can be further improved.

[0039] As in the insulating plate 123 of the first modified example, when the outer peripheral surface 140 has a wavy shape in a cross section perpendicular to the axial direction of the insulating plate 123 passing through the outer peripheral surface 140, and the inner peripheral surface 160 has a wavy shape in a cross section perpendicular to the axial direction of the insulating plate 123 passing through the inner peripheral surface 160, radial forces are likely to be applied to the insulating plate 123 evenly in the circumferential direction, thereby preventing large radial loads from acting on local circumferential positions of the insulating plate 123, and further increasing the fitting strength resistance of the insulating plate 123.

[0040] Assume that the radial distance between the central axis P of the outer can 20 and the outer peripheral surface 140 is defined as the radius of the outer peripheral surface 140, and the radial distance between the central axis P and the inner peripheral surface 160 is defined as the radius of the inner peripheral surface 160. Also assume that the outer peripheral surface 140 and the inner peripheral surface 160 are provided with recesses 141, 142, the maximum radius of the outer peripheral surface 140 is R3, the minimum radius of the inner peripheral surface 160 is R4, the area of ​​a circle with radius R3 is S5, the area of ​​a first plane perpendicular to the axial direction and enclosed by the outer peripheral surface 140 is S6, the area of ​​a circle with radius R4 is S7, and the area of ​​a second plane perpendicular to the axial direction and enclosed by the inner peripheral surface 160 is S8. In this case, in order to effectively improve the fitting strength durability of the insulating plate 23, it is preferable that S6 / S5 is 0.98 or less and S8 / S7 is 1.02 or more.

[0041] Furthermore, when S6 / S5 is 0.94 or more and S8 / S7 is 1.07 or less, sealing plate 22 tends to have a sufficient holding force for insulating plate 123, and insulating plate 123 tends to have a sufficient holding force for terminal plate 21. Therefore, relative movement of insulating plate 23 with respect to sealing plate 22 can be effectively suppressed, and relative movement of terminal plate 21 with respect to insulating plate 123 can also be effectively suppressed.

[0042] When the insulating plate 123 is movable in the radial direction relative to the outer can 20, the maximum radius of the outer circumferential surface 140 is defined as the maximum radius when the insulating plate 123 is disposed relative to the outer can 20 so that the maximum radius is maximized. When the insulating plate 123 is movable in the radial direction relative to the outer can 20, the minimum radius of the inner circumferential surface 160 is defined as the minimum radius when the insulating plate 123 is disposed relative to the outer can 20 so that the minimum radius is minimized.

[0043] As shown in Figure 5, i.e., a top view corresponding to Figure 2 of insulating plate 223 of a second modified example, one or more recesses 242 may be provided on inner circumferential surface 260 abutting the outer circumferential surface of terminal plate 21 without providing a recess on the outer circumferential surface abutting the inner circumferential surface of annular protrusion 34 of sealing plate 22. Even in this case, the radial outward force that insulating plate 223 receives from terminal plate 21 can be reduced, thereby reducing the radial load that insulating plate 223 receives and improving the fitting strength durability of insulating plate 223. Furthermore, because inner circumferential surface 260 has a corrugated shape in a cross section perpendicular to the axial direction of insulating plate 223 passing through inner circumferential surface 260, radial forces are likely to be applied to insulating plate 223 evenly in the circumferential direction, thereby improving the fitting strength durability of insulating plate 223.

[0044] The radius of the inner circumferential surface 260 is defined as the radial distance between the central axis P of the outer can 20 and the inner circumferential surface 260. The inner circumferential surface 260 has a recess 242, the minimum radius of the inner circumferential surface 260 is R2, the area of ​​a circle with radius R2 is S3, and the area of ​​a plane perpendicular to the axial direction and enclosed by the inner circumferential surface 260 is S4. In this case, if S4 / S3 is 1.07 or less, the fitting strength durability of the insulating plate 223 can be effectively improved. Furthermore, if S4 / S3 is 1.02 or more, the holding force of the terminal board 21 in the insulating plate 223 is likely to be sufficient, and relative movement of the terminal board 21 with respect to the insulating plate 223 can be effectively suppressed. Note that, if the insulating plate 223 is movable radially relative to the outer can 20, the minimum radius of the inner circumferential surface 260 is defined as the minimum radius when the insulating plate 223 is positioned relative to the outer can 20 so that the minimum radius is smallest.

[0045] 6 , that is, a top view of an insulating plate 323 of a third modified example corresponding to FIG. 2 , at least one of an outer peripheral surface 340 and an inner peripheral surface 360 ​​of the insulating plate 323 does not have to have a wave shape in a cross section perpendicular to the axial direction of the insulating plate 323, but may have a gear shape, a serration shape, or the like. The shape of one or more recesses provided in at least one of the outer peripheral surface and the inner peripheral surface of the insulating plate in a cross section perpendicular to the axial direction of the insulating plate may be any shape, such as a substantially semicircular shape, a substantially isosceles trapezoidal shape, or a substantially isosceles triangular shape, for example.

[0046] It is preferable to provide a plurality of recesses on at least one of the outer peripheral surface and the inner peripheral surface of the insulating plate, and it is even more preferable to provide a plurality of identical recesses. In this case, it is preferable that two adjacent recesses in the circumferential direction are continuously connected, or that the plurality of recesses are arranged at equal intervals in the circumferential direction. In this way, radial forces are likely to be applied to the insulating plate evenly in the circumferential direction, which makes it possible to prevent large radial loads from being applied to localized positions in the circumferential direction of the insulating plate, and thereby increases the fitting strength durability of the insulating plate.

[0047] When multiple recesses are provided on at least one of the outer peripheral surface and the inner peripheral surface of the insulating plate, the multiple recesses may include two or more non-identical recesses, and may be arranged at uneven intervals in the circumferential direction. Also, at least one of the outer peripheral surface and the inner peripheral surface of the insulating plate may have only one recess.

[0048] REFERENCE SIGNS LIST 10 Battery, 11 Positive electrode, 12 Negative electrode, 13 Separator, 14 Electrode body, 15 Upper insulating plate, 16 Lower insulating plate, 17 Positive electrode lead, 18 Negative electrode lead, 19 Sealing body, 20 Outer can, 20A Bottom, 20B Cylindrical portion, 20C Electrode body accommodating chamber, 21 Terminal plate, 21A Annular portion, 21B Central portion, 21C Vent, 22 Sealing plate, 22A Valve portion, 22B Annular end portion, 23, 123, 223, 323 Insulating plate, 23A Opening, 23B Vent, 24 Gasket, 28 Grooved portion, 29 Shoulder portion, 31 Peripheral portion, 32A Lower convex portion, 32B Thinned portion, 33 Annular space, 34 Annular protrusion of sealing plate, 35 Annular protrusion of insulating plate, 40, 140, 340 Outer surface of insulating plate, 41, 141 Depression in outer surface of insulating plate, 60, 160, 260, 360 Inner surface, 142, 242 Depression in inner surface of insulating plate, P Central axis of outer can.

Claims

1. A cylindrical battery comprising: an electrode assembly in which a positive electrode and a negative electrode are wound with a separator interposed therebetween; an outer can that houses the electrode assembly; and a sealing body that closes the opening of the outer can, wherein the sealing body has a sealing plate with an annular protrusion that protrudes axially toward the electrode assembly, a terminal plate to which an electrode lead extending from the electrode assembly is joined, and an annular insulating plate having an outer peripheral surface that is fitted and fixed to the inner peripheral surface of the annular protrusion and an inner peripheral surface that is fitted and fixed to the outer peripheral surface of the terminal plate, and at least one of the outer peripheral surface and the inner peripheral surface is provided with one or more radially recessed depressions.

2. The cylindrical battery according to claim 1, wherein at least one of the outer peripheral surface and the inner peripheral surface of the insulating plate in a cross section perpendicular to the axial direction has a wave shape with continuously repeated concave and convex portions.

3. A cylindrical battery according to claim 1 or 2, wherein, when the radial distance between the central axis of the outer can and the outer peripheral surface is defined as the radius of the outer peripheral surface, the recess is provided on the outer peripheral surface, the maximum radius of the outer peripheral surface is R1, the area of ​​a circle with radius R1 is S1, and the area of ​​a plane perpendicular to the axial direction and enclosed by the outer peripheral surface is S2, S2 / S1 is 0.94 or more and 0.98 or less.

4. A cylindrical battery according to claim 1 or 2, wherein, when the radial distance between the central axis of the outer can and the inner circumferential surface is defined as the radius of the inner circumferential surface, the recess is provided on the inner circumferential surface, the maximum radius of the inner circumferential surface is R2, the area of ​​a circle having radius R2 is S3, and the area of ​​a plane enclosed by the inner circumferential surface and perpendicular to the axial direction is S4, S4 / S3 is 1.02 or more and 1.07 or less.

5. The cylindrical battery according to claim 1 or 2, wherein, when the radial distance between the central axis of the outer can and the outer peripheral surface is defined as the radius of the outer peripheral surface and the radial distance between the central axis and the inner peripheral surface is defined as the radius of the inner peripheral surface, the recesses are provided on the outer peripheral surface and the inner peripheral surface, the maximum radius of the outer peripheral surface is R3, the maximum radius of the inner peripheral surface is R4, the area of ​​a circle with radius R3 is S5, the area of ​​a first plane perpendicular to the axial direction and enclosed by the outer peripheral surface is S6, the area of ​​a circle with radius R4 is S7, and the area of ​​a second plane perpendicular to the axial direction and enclosed by the inner peripheral surface is S8, S6 / S5 is 0.94 or more and 0.98 or less, and S8 / S7 is 1.02 or more and 1.07 or less.

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