JP7709293B2 - Cylindrical battery - Google Patents

Description

This disclosure relates to cylindrical batteries.

A conventional cylindrical battery is described in Patent Document 1. In this cylindrical battery, tape is attached to the outermost end of the electrode body. The outermost circumference of the electrode body is fixed with the tape, allowing the electrode body to be smoothly inserted into the outer can.

JP 2009-199974 A

When the electrode body expands with the charge/discharge cycles of the battery, the portion of the electrode body to which the tape is attached is not allowed to expand by the thickness of the tape compared to the portion of the electrode body that is not wrapped with tape, and is subjected to greater pressure from the outer can through the tape. In particular, the electrode body is more susceptible to damage due to the edges of the tape.

Therefore, the objective of this disclosure is to provide a cylindrical battery that allows the electrode body to be smoothly inserted into the outer can and suppresses damage to the electrode body caused by the edges of the tape.

To solve the above problem, the cylindrical battery disclosed herein comprises an electrode assembly in which a long positive electrode and a long negative electrode are wound with a separator interposed therebetween, and a bottomed cylindrical outer can that houses the electrode assembly, the electrode assembly having a tape that fixes the outermost periphery, a recess provided at least at a location facing the tape on the inner circumferential surface of the outer can, and at least a portion of the tape in the thickness direction housed in the recess.

The cylindrical battery according to the present disclosure allows the electrode body to be smoothly inserted into the outer can, and reduces damage to the electrode body caused by the edges of the tape.

FIG. 2 is an axial cross-sectional view of a cylindrical battery according to one embodiment of the present disclosure. FIG. 2 is a schematic diagram showing the positional relationship between an exterior can and an electrode assembly in a cylindrical battery. 1 is a schematic diagram illustrating a DI process for forming a recess in an exterior can. FIG. FIG. 2 is a schematic cross-sectional view of an exterior can. FIG. 3 is a schematic diagram corresponding to FIG. 2 and showing a cylindrical battery according to a modified example.

Below, 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. Below, a non-aqueous electrolyte secondary battery (lithium ion battery) using a non-aqueous electrolyte will be exemplified as the cylindrical battery 10, which is one embodiment, but the cylindrical battery according to the present disclosure is not limited thereto.

When multiple embodiments and variations are included below, it is assumed from the beginning that new embodiments will be constructed by appropriately combining the characteristic parts of those. In the following embodiments, the same components are given the same reference numerals in the drawings, and duplicated explanations are omitted. In addition, multiple drawings include schematic diagrams, and the dimensional ratios of the length, width, height, etc. of each component do not necessarily match between different drawings. In this specification, for convenience of explanation, the sealing body 17 side in the axial direction (height direction) of the cylindrical battery 10 is referred to as "upper", and the bottom side of the exterior can 16 in the axial direction is referred to as "lower". Among the components described below, components that are not described in the independent claim showing the highest concept are optional components and are not essential components.

Figure 1 is an axial cross-sectional view of a cylindrical battery 10 according to an embodiment of the present disclosure. As shown in Figure 1, the cylindrical battery 10 includes a wound electrode body 14, a non-aqueous electrolyte (not shown), a cylindrical metal exterior can 16 with a bottom that contains the electrode body 14 and the non-aqueous electrolyte, and a sealing body 17 that closes the opening of the exterior can 16. The electrode body 14 has a wound structure in which a long positive electrode 11 and a long negative electrode 12 are wound with two long separators 13 in between.

The negative electrode 12 is formed with dimensions slightly larger than the positive electrode 11 to prevent lithium precipitation. That is, the negative electrode 12 is formed longer in the longitudinal direction and width direction (short direction) than the positive electrode 11. In addition, the two separators 13 are formed with dimensions at least slightly larger than the positive electrode 11, and are arranged to sandwich the positive electrode 11, for example. The negative electrode 12 may form the winding start end of the electrode body 14. However, in general, the separator 13 extends beyond the winding start end of the negative electrode 12, and the winding start end of the separator 13 becomes the winding start end of the electrode body 14.

The non-aqueous electrolyte includes a non-aqueous solvent and an electrolyte salt dissolved in the non-aqueous solvent. For example, esters, ethers, nitriles, amides, and mixed solvents of two or more of these may be used as the non-aqueous solvent. The non-aqueous solvent may contain a halogen-substituted body in which at least a part of the hydrogen atoms of these solvents is replaced with a halogen atom such as fluorine. The non-aqueous electrolyte is not limited to a liquid electrolyte, and may be a solid electrolyte using a gel polymer or the like. A lithium salt such as _LiPF6 is used as the electrolyte salt.

The positive electrode 11 has a positive electrode current collector and a positive electrode mixture layer formed on both sides of the positive electrode current collector. For the positive electrode current collector, 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 disposed on the surface layer can be used. The positive electrode mixture layer contains a positive electrode active material, a conductive agent, and a binder. The positive electrode 11 can be produced, for example, by applying a positive electrode mixture slurry containing a positive electrode active material, a conductive agent, and a binder, etc., onto the positive electrode current collector, drying the coating, and then compressing it to form a positive electrode mixture layer on both sides of the current collector. The positive electrode mixture layer may be formed on only one side of the positive electrode current collector.

The positive electrode active material is composed mainly of a lithium-containing metal composite oxide. 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.

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

The negative electrode 12 has a negative electrode current collector and a negative electrode mixture layer formed on both sides of the negative electrode current collector. For the negative electrode current collector, a metal foil that is stable in the potential range of the negative electrode 12, such as copper or a copper alloy, or a film with the metal disposed on the surface layer can be used. The negative electrode mixture layer contains a negative electrode active material and a binder. The negative electrode 12 can be produced, for example, by applying a negative electrode mixture slurry containing a negative electrode active material and a binder, etc., onto the negative electrode current collector, drying the coating, and then compressing it to form a negative electrode mixture layer on both sides of the current collector. The negative electrode mixture layer may be formed on only one side of the negative electrode current collector.

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 graphites such as flake graphite, lump graphite, and earthy graphite, and artificial graphites such as lump artificial graphite and graphitized mesophase carbon microbeads. The negative electrode mixture layer may contain a Si material containing silicon (Si) 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 the metal, or a compound containing the metal.

As with the positive electrode 11, the binder contained in the negative electrode mixture layer may be fluororesin, PAN, polyimide resin, acrylic resin, polyolefin resin, etc., but styrene-butadiene rubber (SBR) or a modified form thereof is preferably 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.

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. The material for the separator 13 is preferably a polyolefin resin such as polyethylene or 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.

As shown in FIG. 1, a positive electrode lead 20 is joined to the positive electrode 11, and a negative electrode lead 21 is joined to the winding start side of the negative electrode 12 in the longitudinal direction. The cylindrical battery 10 has an insulating plate 18 above the electrode body 14, and an insulating plate 19 below the electrode body 14. The positive electrode lead 20 extends to the sealing body 17 side through a through hole of the insulating plate 18, and the negative electrode lead 21 extends to the bottom 68 side of the outer can 16 through a through hole of the insulating plate 19. The positive electrode lead 20 is connected to the underside of the bottom plate 23 of the sealing body 17 by welding or the like. The terminal plate 27 constituting the top plate of the sealing body 17 is electrically connected to the bottom plate 23, and the terminal plate 27 becomes a positive electrode terminal. The negative electrode lead 21 is connected to the inner surface of the bottom 68 of the metal outer can 16 by welding or the like, and the outer can 16 becomes a negative electrode terminal.

The cylindrical battery 10 further includes a resin gasket 28 disposed between the exterior can 16 and the sealing body 17. The gasket 28 is sandwiched between the exterior can 16 and the sealing body 17, and insulates the sealing body 17 from the exterior can 16. The gasket 28 serves as a sealant to maintain airtightness inside the battery, and as an insulating material to insulate the exterior can 16 and the sealing body 17. The exterior can 16 has an annular grooved portion 34 in part of the axial direction.

The grooved portion 34 can be formed, for example, by spinning a portion of the side surface radially inward to recess it radially inward. The exterior can 16 has a bottomed tubular portion 30 including the grooved portion 34, and an annular shoulder portion 38. The bottomed tubular portion 30 contains the electrode body 14 and the non-aqueous electrolyte, and the shoulder portion 38 is bent radially inward from the end of the opening side of the bottomed tubular portion 30 and extends inward. The shoulder portion 38 is formed when the upper end of the exterior can 16 is bent inward and crimped to the peripheral portion of the sealing body 17. The sealing body 17 is crimped and fixed to the exterior can 16 via a gasket 28 between the shoulder portion 38 and the grooved portion 34. In this way, the internal space of the cylindrical battery 10 is sealed.

The sealing body 17 has a structure in which, in order from the electrode body 14 side, a bottom plate 23, a lower valve body 24, an insulating member 25, an upper valve body 26, and a terminal plate 27 are stacked. Each member constituting the sealing body 17 has, for example, a disk or ring shape, and each member except for the insulating member 25 is electrically connected to each other. The bottom plate 23 has at least one through hole 23a. In addition, the lower valve body 24 and the upper valve body 26 are connected at their respective centers, and an insulating member 25 is interposed between their respective peripheral portions.

When the cylindrical battery 10 generates abnormal heat and the internal pressure of the cylindrical battery 10 rises, the lower valve body 24 deforms and breaks as it pushes the upper valve body 26 towards the terminal plate 27, cutting off the current path between the lower valve body 24 and the upper valve body 26. If the internal pressure rises further, the upper valve body 26 breaks and gas is discharged from the through hole 27a of the terminal plate 27. This gas discharge prevents the internal pressure of the cylindrical battery 10 from rising excessively, which could cause the cylindrical battery 10 to explode, thereby increasing the safety of the cylindrical battery 10.

Next, the heat dissipation structure of the cylindrical battery 10, the fixing structure of the electrode body 14 by the tape 39, and the tape housing structure of the outer can will be described. In the cylindrical battery 10, the negative electrode 12 is arranged on the outermost circumference of the electrode body 14. The tape 39 is attached to the outer surface of the end of the winding end of the negative electrode 12 so as to fix the end of the electrode body 14. The end of the winding end of the negative electrode 12 has an exposed portion 33 on its outer surface where the negative electrode mixture layer is not arranged and the negative electrode current collector is exposed. This exposed portion 33 is arranged on the outermost surface 42 of the electrode body 14. In other words, the tape 39 is arranged on the outermost surface 42 of the electrode body 14 together with the exposed portion 33 of the negative electrode current collector. The tape 39 may be made of any material as long as it can fix the end of the electrode body 14. For example, a two-layer tape consisting of a base layer and an adhesive layer can be used as the tape 39.

The substrate layer may contain inorganic particles, or may be composed of only organic materials without inorganic particles. The ratio of organic materials to the constituent materials of the substrate layer may be, for example, 90% by mass or more, 95% by mass or more, or approximately 100% by mass. As the main component of the substrate layer, for example, ester resins such as polypropylene (PP) and polyethylene terephthalate (PET), polyimide (PI), polyphenylene sulfide, polyamide, etc. may be used. As the main component of the substrate layer, one of these resins may be used alone, or two or more of these resins may be used in combination.

The adhesive layer is a layer for imparting adhesiveness to the tape 39 with respect to the electrode body 14. The adhesive layer is formed by applying an adhesive onto one surface of the base layer. The adhesive layer can be formed using an adhesive (resin) with excellent insulating properties, electrolyte resistance, etc. The adhesive constituting the adhesive layer may be a hot melt type that exhibits adhesiveness when heated or a thermosetting type that hardens when heated, or may be one that has adhesiveness at room temperature. The adhesive layer is formed, for example, from an acrylic adhesive or a synthetic rubber adhesive.

The tape 39 is not limited to a two-layer tape, and may be, for example, a three-layer tape in which an inorganic particle-containing layer is formed between the base layer and the adhesive layer. By using a three-layer tape, the heat resistance of the adhesive tape can be improved. The inorganic particle-containing layer may have a layer structure in which inorganic particles are dispersed in a resin matrix constituting the layer. The inorganic particle-containing layer is formed, for example, by applying a resin solution containing inorganic particles onto one side of the base layer. Examples of resins constituting the inorganic particle-containing layer include acrylic resins, urethane resins, and copolymers thereof. As the inorganic particle-containing layer, one of these resins may be used alone, or two or more of these resins may be used in combination.

Figure 2 is a schematic diagram showing the positional relationship between the exterior can 16 and the electrode body 14 in a cylindrical battery 10. The tape 39 is placed around the entire circumferential direction on the outermost surface 42 of the electrode body 14. This allows the end of the electrode body 14 to be fixed to other parts of the electrode body 14. As shown in Figure 2, the tape 39 is placed only on both axial ends of the electrode body 14, and is composed of a first tape portion 39a placed at the first axial end (upper end) of the electrode body 14 and a second tape portion 39b placed at the second axial end (lower end) of the electrode body 14.

A recess 45 is provided at least at a location radially opposed to the tape 39 on the inner peripheral surface of the outer can 16. More specifically, the recess 45 is composed of an annular first recess 45a provided at a location radially opposed to the first tape portion 39a, and an annular second recess 45b provided at a location radially opposed to the second tape portion 39b. The second recess 45b is positioned at a distance in the axial direction from the first recess 45a. The first tape portion 39a is housed in the first recess 45a, and the second tape portion 39b is housed in the second recess 45b.

In this embodiment, the end of the electrode body 14 can be fixed with tape 39, so the wound structure of the electrode body 14 can be maintained. This allows the electrode body 14 to be smoothly inserted into the outer can 16, improving the mass productivity of the cylindrical battery 10.

In addition, a recess 45 is provided on the inner circumferential surface of the exterior can 16 at a location radially corresponding to the tape 39, so that at least a portion of the thickness of the tape 39 is accommodated within the recess 45. Therefore, compared to a case in which an exterior can without a recess on the inner circumferential surface is used, the pressure received from the inner circumferential surface of the exterior can 16 at the locations on the outermost circumferential surface 42 of the electrode body 14 where the tape 39 is arranged and at the locations where the tape 39 is not arranged can be made uniform. Therefore, damage to the electrode body 14 caused by the edge of the tape 39 can be suppressed.

The tape 39 is disposed only on both axial ends of the electrode body 14 and is housed in recesses 45 spaced apart in the axial direction. Therefore, the exposed portion 33 located in the axial center of the outermost surface 42 of the electrode body 14 can be brought into close contact with the inner circumferential surface of the outer can 16. As a result, heat generated in the electrode body 14 during charging and discharging of the cylindrical battery 10 can be efficiently dissipated through the exposed portion 33, and the electrode body 14 can be efficiently cooled. This makes it possible to suppress thermal deterioration of the electrode body 14 and increase the capacity retention rate when charging and discharging are repeated.

In addition, by contacting the exterior can 16 with the exposed portion 33, the end of the long negative electrode current collector 32 at the end of the winding is electrically connected to the exterior can 16 as the negative electrode terminal. Therefore, the start of the winding of the long negative electrode current collector 32 can be electrically connected to the exterior can 16 using the negative electrode lead 21, and the end of the winding of the negative electrode current collector 32 can also be electrically connected to the exterior can 16, so that the electrical resistance of the path from the negative electrode 12 to the exterior can 16 can be reduced, and power loss can be reduced.

Generally, when inserting the electrode body into an outer can, both axial ends of the outermost periphery of the electrode body are likely to get caught on the outer can. In contrast, by arranging tape 39 at both axial ends of the outermost surface 42 as in this embodiment, it is possible to significantly reduce the outermost periphery from getting caught on the outer can 16. Therefore, the electrode body 14 can be smoothly inserted into the outer can 16, improving the mass productivity of the cylindrical battery 10.

The recess 45 for accommodating the tape 39 is provided in an annular shape around the entire inner circumferential surface of the outer can 16. Therefore, even if the tape is not placed around the entire outermost surface of the electrode body, the tape can be accommodated in the recess regardless of the relative circumferential position of the tape with respect to the outer can. This allows for greater freedom in the relative position of the electrode body with respect to the outer can when inserting the electrode body into the outer can.

In the cylindrical battery of the present disclosure, the negative electrode 12 may be electrically connected to the outer can 16 by only contacting the outer can 16 with the exposed portion 33, and the negative electrode lead may be omitted. Alternatively, a separator may be disposed on the outermost periphery of the electrode body. Then, a negative electrode lead may be joined to an exposed portion of the negative electrode current collector provided on at least one of the end portion on the winding start side and the end portion on the winding end side in the longitudinal direction of the electrode body, and the negative electrode lead may be joined to the outer can.

Next, a method for producing the outer can 16 having the recess 45 described above will be described. FIG. 3 is a schematic diagram for explaining the DI (Drawing Ironing) method for forming the recess 45 in the outer can 16. In this method, first, as shown in FIG. 3, a flat steel sheet 62 is sandwiched between two dies 60, 61 that define a cup-shaped shape, and the steel sheet 62 is bent to form the steel sheet 62 into a cup shape. Next, a punch 65 having a shape corresponding to the electrode arrangement space of the outer can 16 is placed in the cup-shaped steel sheet 62. In addition, a plurality of annular dies 85, 86, 87 with different inner diameters are stacked and fixed in order of increasing inner diameter. Then, the cup-shaped steel sheet 62 with the punch 65 placed inside is passed from the side with the larger inner diameter to the side with the smaller inner diameter of the plurality of dies 85, 86, 87 stacked and fixed from the bottom side. In this way, the cup-shaped steel plate 62 is subjected to ironing to gradually reduce the outer diameter of the cup-shaped steel plate 62, producing a bottomed cylindrical member 71 that has a constant outer diameter in the axial direction.

A punch 65 is fitted inside the bottomed cylindrical member 71. The punch 65 has two annular projections 65a, 65b that correspond to the two recesses 45a, 45b spaced apart in the axial direction. As a result, the thickness of the portion 71a of the cylindrical portion of the cylindrical member 71 that faces the two annular projections 65a, 65b of the punch 65 in the radial direction is thinner than the thickness of the other portion 71b. Thereafter, as shown in FIG. 3, the punch 65 is removed from the cylindrical member 71 to produce the outer can 16. Note that the method of producing the outer can 16 is not limited to the DI method.

As shown in FIG. 3, tapered portions 64a, 64b are provided at both axial ends of the protrusions 65a, 65b of the punch 65, the outer diameter of which gradually decreases as it approaches the axial outside. In this way, as shown in FIG. 4, tapered portions 46a, 46b are formed at both axial ends of the recess 45 of the outer can 16, the inner diameter of which gradually decreases as it approaches the axial outside. A curved surface portion may be interposed between the tapered portions 46a, 46b and the bottom 47 of the recess 45. By providing the tapered portions 64a, 64b on the punch 65, the punch 65 can be easily removed from the cylindrical member 71. In addition, by forming the tapered portions 46a, 46b on the outer can 16, even if there is variation in the axial attachment position of the tape 39 relative to the electrode body 14, damage to the electrode body 14 caused by the edge of the tape 39 can be effectively suppressed.

[Example 1]
(Preparation of Positive Electrode)
A lithium nickel composite oxide represented _{by LiNi0.88Co0.09Al0.03O2} was used as the positive electrode active material. 100 parts by mass of this positive electrode active material was mixed with 1 part by mass of acetylene black as a carbon conductive agent and 0.9 parts _by mass _of polyvinylidene fluoride as a binder, and an appropriate amount of NMP (N-methyl-2-pyrrolidone) was added to prepare a positive electrode mixture slurry. This positive electrode mixture slurry was applied to both sides of an aluminum positive electrode current collector, dried and rolled to prepare a positive electrode.

(Preparation of negative electrode)
Graphite powder was mixed to 95 parts by mass and Si oxide was mixed to 5 parts by mass. Then, 1 part by mass of carboxymethyl cellulose (CMC) as a thickener and 0.1 part by mass of styrene butadiene rubber (SBR) as a binder were dispersed in water to prepare a negative electrode mixture slurry. This negative electrode mixture slurry was applied to both sides of a copper foil negative electrode current collector, dried and rolled to prepare a negative electrode.

(Preparation of electrode body)
The positive and negative electrodes were wound with a separator made of a polyethylene microporous film interposed therebetween to prepare an electrode body in which the negative electrode was located at the outermost periphery. In addition, an exposed portion was provided on the outer peripheral surface of the outermost negative electrode, in which the copper foil serving as the negative electrode current collector was exposed. In addition, a negative electrode lead was welded to the start side of the winding of the negative electrode, and the end of the exposed portion at the outermost periphery was fixed with tape. The tape used had a thickness of 0.03 mm and a width of 9 mm. An aluminum lead was used as the positive electrode lead, and a nickel lead was used as the negative electrode lead.

(Fabrication of outer can)
The outer can was made by punching a nickel-plated steel sheet into a circle and forming a cylindrical can with a bottom by the DI method. At this time, a punch having a shape shown in FIG. 3 was used, and the outer diameter of the punch at the portion facing the tape attached to the outermost circumference of the electrode body was set to be larger by the thickness of the tape. This provided a recess on the inner peripheral surface of the outer can. In addition, the above-mentioned tapered portion and curved surface portion were provided in the recess of the outer can. The width of the bottom of the recess was 9 mm, and the depth of the recess was 0.03 mm.

(Preparation of non-aqueous electrolyte)
A non-aqueous electrolyte was prepared by adding ₅ parts by mass of vinylene carbonate (VC) to 80 parts by mass of a mixed solvent consisting of ethylene carbonate (EC) and dimethyl methyl carbonate (DMC) (volume ratio of EC:DMC=1:3), and dissolving LiPF6 at 1.5 mol/L.

(Preparation of Cylindrical Battery)
A cylindrical non-aqueous electrolyte secondary battery was fabricated using the above electrode assembly, outer can, and non-aqueous electrolyte. The tape of the electrode assembly was placed in a recess in the outer can.

[Example 2]
A cylindrical battery of Example 2 was fabricated in the same manner as in Example 1, except that the depth of the recess in the outer can was 0.024 mm.

[Example 3]
A cylindrical battery of Example 3 was fabricated in the same manner as in Example 1, except that the depth of the recess in the outer can was 0.036 mm.

[Comparative Example]
A cylindrical battery of the comparative example was fabricated in the same manner as in Example 1, except that no recess was provided in the exterior can.

[Cycle test]
Each cylindrical battery was charged at a constant current of 0.5 It until it reached 4.2 V, and then charged at a constant voltage of 4.2 V until the current value reached 0.05 It. The battery was also discharged at a constant current of 0.5 It until the voltage reached 2.5 V. After repeating this charge-discharge cycle 100 times, the battery was disassembled and visually inspected for deformation of the electrode body due to the edge of the tape. The results are shown in Table 1.

As shown in Table 1, in the comparative example in which no recess was provided at the location radially facing the tape on the outer can, deformation due to the axial edge of the tape on the electrode body was confirmed. On the other hand, in Examples 1 to 3 in which a recess was provided at the location radially facing the tape on the outer can, no deformation due to the axial edge of the tape on the electrode body was observed. From this, it can be seen that by providing a recess at the location radially facing the tape on the outer can, damage to the electrode body due to the edge of the tape can be suppressed.

In the above examples, the presence or absence of deformation of the electrode body was confirmed when the depth of the recess was 80% or more and 120% or less of the tape thickness. However, regardless of the dimension of the depth of the recess provided in the outer can at a location radially opposite the tape, at least a portion of the thickness of the tape corresponding to that depth can be accommodated within the recess, and stress generated in the electrode body due to the edge of the tape can be reduced. Therefore, by providing a recess in the outer can at a location radially opposite the tape, damage to the electrode body due to the edge of the tape can be suppressed regardless of the value of the depth of the recess.

Furthermore, this disclosure is not limited to the above-described embodiment and its modified examples, and various improvements and modifications are possible within the scope of the claims of this application and their equivalents.

For example, in the above embodiment, the tape 39 is disposed at both axial ends of the electrode body 14. However, the tape may be disposed at only one axial end of the electrode body. Alternatively, the tape may be fixed to a range including the central portion of the electrode body in the axial direction, for example, the tape may be disposed only at the central portion of the electrode body in the axial direction.

Also, the case where the tape 39 is arranged around the entire circumference of the outermost circumference of the electrode body 14 and the tape 39 is accommodated in the annular recess 45 provided on the inner surface of the outer can 16 has been described. However, as shown in FIG. 5, i.e., a schematic diagram corresponding to FIG. 2 of the modified cylindrical battery 110, the tape 139 may be arranged only on a part of the circumference including the terminal end of the outermost circumference of the electrode body 14. In this case, a non-annular recess 145 may be provided in an area including a portion facing the tape 139 on the inner surface of the outer can 116. Then, at least a part of the thickness direction of the tape 139 may be accommodated in the recess 145. Such a recess 145 can be easily formed by providing a non-annular protrusion on the punch used in the DI method for manufacturing the outer can 116.

LIST OF SYMBOLS 10,110 CYLINDRICAL BATTERY, 11 POSITIVE ELECTRICITY, 12 NEGATIVE ELECTRICITY, 13 SEPARATOR, 14 ELECTRODE BODY, 16,116 EXTERNAL CAN, 17 SEALING BODY, 20 POSITIVE ELECTRICITY LEAD, 21 NEGATIVE ELECTRICITY LEAD, 28 GASKET, 30 BOTTOM TURBINE PORTION, 32 NEGATIVE ELECTRIC ELECTRIC CURRENT COLLECTOR, 33 EXPOSED PORTION, 34 GROOVED PORTION, 38 SHOULDER PORTION, 39,139 TAPE, 39a FIRST TAPE PORTION, 39b SECOND TAPE PORTION, 42 OUTER PERIPHERAL SURFACE, 45,145 CONVENTION, 45a FIRST RECEPTION, 45b SECOND RECEPTION, 46a,46b TAPERED PORTION, 47 BOTTOM, 60,61 DIE, 62 STEEL PLATE, 64a,64b TAPERED PORTION, 65 PUNCH, 65a,65b Convex portion, 68 bottom portion, 71 cylindrical member, 85, 86, 87 dies.

Claims (6)

an electrode assembly in which a long positive electrode and a long negative electrode are wound with a separator interposed therebetween;
a bottomed cylindrical exterior can for accommodating the electrode assembly;
The electrode body has a tape for fixing a terminal end of the electrode body,
a recess is provided at least at a portion of an inner circumferential surface of the outer can facing the tape,
At least a portion of the tape in the thickness direction is accommodated in the recess. The cylindrical battery according to claim 1, wherein the recess is provided on the entire inner circumferential surface. the negative electrode has a long negative electrode current collector and a negative electrode mixture layer provided on at least one side surface of the negative electrode current collector,
an exposed portion in which the negative electrode current collector is exposed is disposed on at least a part of the outermost peripheral surface of the electrode body;
The cylindrical battery according to claim 1 , wherein at least a portion of the exposed portion is in contact with the inner circumferential surface. 4. The cylindrical battery of claim 3, wherein the tape is composed of a first tape portion arranged at a first end of the electrode body in the axial direction of the cylindrical battery and a second tape portion arranged at a second end of the electrode body in the axial direction. 5. The cylindrical battery according to claim 1, wherein an end of the recess in the axial direction of the cylindrical battery on the opening side of the outer can has a tapered shape in which the inner diameter becomes smaller toward the opening side in the axial direction. 6. The cylindrical battery according to claim 1, wherein the recess has a depth of 80% or more and 120% or less of the thickness of the tape.