Cylindrical battery

Abstract

To provide a cylindrical battery capable of smoothly inserting an electrode body into an outer can and suppressing damage caused by an edge of a tape on the electrode body.SOLUTION: A cylindrical battery 10 has an electrode body 14 consisting of a long positive electrode 11 and a long negative electrode 12 wound through a separator 13 and a bottomed tubular outer can 16 that accommodates the electrode body 14. The electrode body 14 has a tape 39 for fixing an end of the electrode body 14. A recess 45 is provided at a portion on the inner surface of the outer can 16 facing at least to the tape 39. At least a part of the tape 39 in the thickness direction is accommodated in the recess 45.SELECTED DRAWING: Figure 1

Description

Technical Field

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

Background Art

[0002] Conventionally, as a cylindrical battery, there is one described in Patent Document 1. In this cylindrical battery, a tape is attached to the end portion of the outermost circumference of the electrode body. The outermost circumference of the electrode body is fixed with the tape so that the electrode body can be smoothly inserted into the outer can.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] When the electrode body expands with the charge and discharge cycles of the battery, the portion of the electrode body where the tape is attached is not allowed to expand by the thickness of the tape compared to the portion of the electrode body where the tape is not wound, and thus receives a greater pressure from the outer can through the tape. In particular, the electrode body is likely to be damaged due to the edge of the tape.

[0005] Therefore, an object of the present disclosure is to provide a cylindrical battery that can smoothly insert the electrode body into the outer can and suppress damage caused by the edge of the tape on the electrode body.

Means for Solving the Problems

[0006] To solve the above problems, the cylindrical battery of the present disclosure includes an electrode body 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 body. The electrode body has a tape for fixing the outermost circumference, and a recess is provided at least at a position facing the tape on the inner circumferential surface of the outer can, and at least a part in the thickness direction of the tape is accommodated in the recess.

Effect of the Invention

[0007] According to the cylindrical battery according to the present disclosure, the electrode body can be smoothly inserted into the outer can, and damage caused by the edge of the tape in the electrode body can be suppressed.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Mode for Carrying Out the Invention

[0009] Hereinafter, embodiments of the cylindrical battery according to the present disclosure will be described in detail with reference to the drawings. The cylindrical battery of the present disclosure may be a primary battery or a secondary battery. Also, it may be a battery using an aqueous electrolyte or a battery using a non-aqueous electrolyte. Hereinafter, as a cylindrical battery 10 which is an embodiment, a non-aqueous electrolyte secondary battery (lithium ion battery) using a non-aqueous electrolyte is exemplified, but the cylindrical battery of the present disclosure is not limited thereto.

[0010] When multiple embodiments, variations, etc. are included below, it is initially assumed that new embodiments can be constructed by appropriately combining their characteristic parts. In the following embodiments, the same reference numerals are given to the same configurations in the drawings, and duplicate explanations are omitted. Also, the plurality of drawings include schematic diagrams, and the dimensional ratios of length, width, height, etc. of each member between different drawings do not necessarily match. In this specification, for the sake of convenience of explanation, the side of the sealing body 17 in the axial direction (height direction) of the cylindrical battery 10 is referred to as "upper", and the bottom side of the outer can 16 in the axial direction is referred to as "lower". Among the components described below, the components not described in the independent claims indicating the highest-level concept are optional components and not essential components.

[0011] FIG. 1 is a cross-sectional view of a cylindrical battery 10 in the axial direction according to an embodiment of the present disclosure. As shown in FIG. 1, the cylindrical battery 10 includes a wound electrode body 14, a non-aqueous electrolyte (not shown), a bottomed cylindrical metal outer can 16 that houses the electrode body 14 and the non-aqueous electrolyte, and a sealing body 17 that closes the opening of the outer 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 via two long separators 13.

[0012] The negative electrode 12 is formed to be slightly larger in size than the positive electrode 11 in order to prevent the precipitation of lithium. That is, the negative electrode 12 is formed longer than the positive electrode 11 in the longitudinal direction and the width direction (short side direction). Also, the two separators 13 are formed to be at least slightly larger in size than the positive electrode 11 and are arranged, for example, so as to sandwich the positive electrode 11. The negative electrode 12 may constitute the winding start end of the electrode body 14. However, generally, the separator 13 extends beyond the winding start side end of the negative electrode 12, and the winding start side end of the separator 13 becomes the winding start end of the electrode body 14.

[0013] The non-aqueous electrolyte contains a non-aqueous solvent and an electrolyte salt dissolved in the non-aqueous solvent. As the non-aqueous solvent, for example, esters, ethers, nitriles, amides, and mixed solvents of two or more of these may be used. The non-aqueous solvent may contain a halogen-substituted product in which at least a part of the hydrogen atoms of these solvents are substituted with halogen atoms such as fluorine. Note that the non-aqueous electrolyte is not limited to a liquid electrolyte, and may be a solid electrolyte using a gel-like polymer or the like. As the electrolyte salt, a lithium salt such as LiPF6 is used.

[0014] The positive electrode 11 has a positive electrode current collector and positive electrode mixture layers formed on both surfaces of the positive electrode current collector. As the positive electrode current collector, a metal foil stable within the potential range of the positive electrode 11, such as aluminum or an aluminum alloy, or a film having 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 manufactured, for example, by applying a positive electrode mixture slurry containing a positive electrode active material, a conductive agent, a binder, etc. onto the positive electrode current collector, drying the coating film, and then compressing it to form the positive electrode mixture layers on both surfaces of the current collector. Note that the positive electrode mixture layer may be formed only on one side of the positive electrode current collector.

[0015] The positive electrode active material is mainly composed of a lithium-containing metal composite oxide. Examples of the 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, W, etc. An example of a preferable lithium-containing metal composite oxide is a composite oxide containing at least one of Ni, Co, Mn, and Al.

[0016] Examples of the conductive agent contained in the positive electrode active material layer include carbon materials such as carbon black, acetylene black, ketjen black, and graphite. Examples of the binder contained in the positive electrode active material layer include fluororesins such as polytetrafluoroethylene (PTFE) and polyvinylidene fluoride (PVdF), polyacrylonitrile (PAN), polyimide resin, acrylic resin, and polyolefin resin. These resins may be used in combination with cellulose derivatives such as carboxymethyl cellulose (CMC) or its salts, and polyethylene oxide (PEO).

[0017] The negative electrode 12 has a negative electrode current collector and negative electrode active material layers formed on both sides of the negative electrode current collector. As the negative electrode current collector, 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 such a metal disposed on its surface layer can be used. The negative electrode active material layer contains a negative electrode active material and a binder. The negative electrode 12 can be manufactured, for example, by applying a negative electrode active material slurry containing a negative electrode active material, a binder, etc. onto the negative electrode current collector, drying the coating film, and then compressing it to form negative electrode active material layers on both sides of the current collector. Note that the negative electrode active material layer may be formed on only one side of the negative electrode current collector.

[0018] Generally, a carbon material that reversibly intercalates and releases lithium ions is used as the negative electrode active material. Preferred carbon materials are graphite such as flake graphite, massive graphite, and earthy graphite, artificial graphite such as massive artificial graphite, and graphitized mesophase carbon microbeads. The negative electrode active material layer may contain an Si material containing silicon (Si) as the negative electrode active material. Further, as the negative electrode active material, a metal that alloys with lithium other than Si, an alloy containing such a metal, a compound containing such a metal, etc. may be used.

[0019] As the binder contained in the negative electrode active material layer, fluororesins, PAN, polyimide resin, acrylic resin, polyolefin resin, etc. may be used as in the case of the positive electrode 11, but preferably styrene-butadiene rubber (SBR) or a modified product thereof is used. The negative electrode active material layer may contain, for example, in addition to SBR, CMC or its salts, polyacrylic acid (PAA) or its salts, polyvinyl alcohol, etc.

[0020] For the separator 13, a porous sheet having ion permeability and insulation is used. Specific examples of the porous sheet include microporous thin films, woven fabrics, non-woven fabrics, etc. As the material of the separator 13, polyolefin resins such as polyethylene and polypropylene, cellulose, etc. are preferable. 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 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 in the longitudinal direction of the negative electrode 12. 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 toward the sealing body 17 through the through-hole of the insulating plate 18, and the negative electrode lead 21 extends toward the bottom 68 side of the outer can 16 through the through-hole of the insulating plate 19. The positive electrode lead 20 is connected to the lower surface 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 serves as the positive electrode terminal. Also, 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 serves as the negative electrode terminal.

[0022] The cylindrical battery 10 further includes a resin gasket 28 disposed between the outer can 16 and the sealing body 17. The gasket 28 is sandwiched between the outer can 16 and the sealing body 17 and insulates the sealing body 17 from the outer can 16. The gasket 28 serves as a sealing material for maintaining the airtightness inside the battery and as an insulating material for insulating the outer can 16 and the sealing body 17. The outer can 16 has an annular groove portion 34 in a part of the axial direction.

[0023] The grooving portion 34 can be formed, for example, by spinning a part of the side surface radially inward to form a depression radially inward. The outer can 16 has a bottomed cylindrical portion 30 including the grooving portion 34 and an annular shoulder portion 38. The bottomed cylindrical portion 30 houses the electrode body 14 and the non-aqueous electrolyte, and the shoulder portion 38 is bent radially inward from the end portion on the opening side of the bottomed cylindrical portion 30 and extends inward. The shoulder portion 38 is formed when the upper end portion of the outer can 16 is bent inward and caulked to the peripheral edge portion of the sealing body 17. The sealing body 17 is caulked and fixed to the outer can 16 via a gasket 28 between the shoulder portion 38 and the grooving portion 34. In this way, the internal space of the cylindrical battery 10 is sealed.

[0024] The sealing body 17 has a structure in which a bottom plate 23, a lower valve body 24, an insulating member 25, an upper valve body 26, and a terminal plate 27 are laminated in order from the electrode body 14 side. Each member constituting the sealing body 17 has, for example, a disc shape or a ring shape, and each member except the insulating member 25 is electrically connected to each other. The bottom plate 23 has at least one through hole 23a. Further, the lower valve body 24 and the upper valve body 26 are connected at their respective central portions, and an insulating member 25 is interposed between their respective peripheral edge portions.

[0025] When the cylindrical battery 10 abnormally generates heat and the internal pressure of the cylindrical battery 10 rises, the lower valve body 24 deforms and breaks so as to push up the upper valve body 26 toward the terminal plate 27 side, and the current path between the lower valve body 24 and the upper valve body 26 is interrupted. When the internal pressure further rises, the upper valve body 26 breaks, and gas is discharged from the through hole 27a of the terminal plate 27. By discharging this gas, it is possible to prevent the internal pressure of the cylindrical battery 10 from rising excessively and the cylindrical battery 10 from bursting, and the safety of the cylindrical battery 10 can be improved.

[0026] 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 accommodation structure of the outer can will be described. In the cylindrical battery 10, the negative electrode 12 is disposed on the outermost periphery of the electrode body 14. The tape 39 is adhered to the outer surface of the end portion on the winding end side of the negative electrode 12 so as to fix the end portion of the electrode body 14. The end portion on the winding end side of the negative electrode 12 has an exposed portion 33 where the negative electrode current collector is exposed without the negative electrode mixture layer being disposed on its outer surface. This exposed portion 33 is disposed on the outermost peripheral surface 42 of the electrode body 14. That is, the tape 39 is disposed on the outermost peripheral 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 portion of the electrode body 14. As the tape 39, for example, a two-layer tape composed of a base material layer and an adhesive layer can be employed.

[0027] The base material layer may contain inorganic particles or may be composed of only an organic material without containing inorganic particles. The proportion of the organic material in the constituent material of the base material 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 base material layer, for example, ester-based resins such as polypropylene (PP) and polyethylene terephthalate (PET), polyimide (PI), polyphenylene sulfide, polyamide, etc. can be adopted. As the main component of the base material layer, one of these resins may be adopted alone, or two or more of these resins may be adopted in combination.

[0028] 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 coating an adhesive on one surface of the base material layer. The adhesive layer can be configured using an adhesive (resin) excellent in insulating properties, electrolyte resistance, etc. The adhesive constituting the adhesive layer may be a hot melt type that exhibits adhesiveness by heating or a thermosetting type that cures by heating, or may have adhesiveness at room temperature. The adhesive layer is composed of, for example, an acrylic-based adhesive or a synthetic rubber-based adhesive.

[0029] 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 a base material layer and an 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 coating a resin solution containing inorganic particles on one surface of the base material layer. Examples of the resin 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.

[0030] FIG. 2 is a schematic diagram showing the positional relationship between the outer can 16 and the electrode body 14 in the cylindrical battery 10. The tape 39 is disposed over the entire circumference in the circumferential direction on the outermost peripheral surface 42 of the electrode body 14. Thereby, the terminal portion of the electrode body 14 is fixed to the other portion of the electrode body 14. As shown in FIG. 2, the tape 39 is disposed only at both axial ends of the electrode body 14, and includes a first tape portion 39a disposed at the first axial end (upper end portion) of the electrode body 14 in the axial direction and a second tape portion 39b disposed at the second axial end (lower end portion) of the electrode body 14 in the axial direction.

[0031] Recesses 45 are provided at at least locations on the inner peripheral surface of the outer can 16 that are radially opposed to the tape 39. Specifically, the recess 45 includes 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 axially spaced from the first recess 45a. The first tape portion 39a is received in the first recess 45a, and the second tape portion 39b is received in the second recess 45b.

[0032] According to the present embodiment, since the terminal portion of the electrode body 14 can be fixed by the tape 39, the winding structure of the electrode body 14 can be maintained. Therefore, the electrode body 14 can be smoothly inserted into the outer can 16, and the mass productivity of the cylindrical battery 10 can be improved.

[0033] Further, since the concave portion 45 is provided at a position on the inner peripheral surface of the outer can 16 corresponding to the tape 39 in the radial direction, at least a part of the tape 39 in the thickness direction is accommodated in the concave portion 45. Therefore, in comparison with the case where an outer can having no concave portion on the inner peripheral surface is adopted, the pressure received from the inner peripheral surface of the outer can 16 by each of the portion where the tape 39 is disposed and the portion where the tape 39 is not disposed on the outermost peripheral surface 42 of the electrode body 14 can be made uniform. Thus, damage to the electrode body 14 caused by the edge of the tape 39 can be suppressed.

[0034] Further, the tape 39 is disposed only at both axial ends of the electrode body 14 and is accommodated in the concave portions 45 provided at intervals in the axial direction. Therefore, the exposed portion 33 located at the central portion in the axial direction of the outermost peripheral surface 42 of the electrode body 14 can be brought into contact with the inner peripheral surface of the outer can 16 in a state of being in close contact therewith. Thus, the 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. Therefore, thermal degradation of the electrode body 14 can be suppressed, and the capacity retention rate when charging and discharging are repeated can be increased.

[0035] Further, when the outer can 16 comes into contact with the exposed portion 33, the end portion on the winding end side of the long negative electrode current collector 32 is electrically connected to the outer can 16 as a negative electrode terminal. Therefore, the start side of the long negative electrode current collector 32 can be electrically connected to the outer can 16 using the negative electrode lead 21, and the winding end side of the negative electrode current collector 32 can also be electrically connected to the outer can 16. Thus, the electrical resistance of the path from the negative electrode 12 to the outer can 16 can be reduced, and the power loss can be reduced.

[0036] Generally, when inserting the electrode body into the outer can, the both axial ends of the outermost peripheral portion of the electrode body are likely to be caught by the outer can. On the other hand, when the tape 39 is disposed at both axial ends of the outermost peripheral surface 42 as in the present embodiment, the catching of the outermost peripheral portion by the outer can 16 can be greatly suppressed. Therefore, the electrode body 14 can be smoothly inserted into the outer can 16, and the mass productivity of the cylindrical battery 10 is improved.

[0037] The recess 45 for accommodating the tape 39 is provided annularly over the entire circumference on the inner peripheral surface of the outer can 16. Therefore, even when the tape is not arranged over the entire circumference of the outermost peripheral surface of the electrode body, the tape can be accommodated in the recess regardless of the circumferential relative position of the tape with respect to the outer can. Thus, the degree of freedom of the relative position of the electrode body with respect to the outer can when inserting the electrode body into the outer can can be increased.

[0038] In the cylindrical battery of the present disclosure, the negative electrode 12 may be electrically connected to the outer can 16 only by the contact between the outer can 16 and the exposed portion 33, and the negative electrode lead may be omitted. Alternatively, a separator may be arranged on the outermost periphery of the electrode body. Then, a negative electrode lead may be joined to the exposed portion of the negative electrode current collector provided at at least one of the end portions in the winding start side and the winding end side in the longitudinal direction of the electrode body, and the negative electrode lead may be joined to the outer can.

[0039] Next, a method for manufacturing the outer can 16 having the recess 45 described above will be described. FIG. 3 is a schematic diagram for explaining a DI (Drawing Ironing) method for forming the recess 45 in the outer can 16. In this method, first, as shown in FIG. 3, the flat steel plate 62 is bent by sandwiching the flat steel plate 62 with two dies 60 and 61 defining a cup shape, thereby forming the steel plate 62 into a cup shape. Next, a punch 65 having a shape corresponding to the electrode body arrangement space of the outer can 16 is arranged inside the cup-shaped steel plate 62. Further, a plurality of annular dies 85, 86, 87 having different inner diameters are stacked and fixed in descending order of the inner diameter. Thereafter, the cup-shaped steel plate 62 having the punch 65 arranged therein 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 fixed by stacking from the bottom side. In this way, ironing is performed on the cup-shaped steel plate 62 to gradually reduce the outer diameter of the cup-shaped steel plate 62, thereby producing a bottomed cylindrical member 71 having a constant outer diameter in the axial direction.

[0040] Inside the bottomed cylindrical member 71, a punch 65 is fitted. The punch 65 has two annular convex portions 65a and 65b having a shape corresponding to two concave portions 45a and 45b spaced apart in the axial direction. From this, in the cylindrical portion of the cylindrical member 71, the thickness of the portion 71a radially opposed to the two annular convex portions 65a and 65b of the punch 65 is thinner than the thickness of the other portion 71b. Thereafter, as shown in FIG. 3, the outer can 16 can be manufactured by removing the punch 65 from the cylindrical member 71. Note that the manufacturing method of the outer can 16 is not limited to the DI method.

[0041] As shown in FIG. 3, taper portions 64a and 64b whose outer diameter gradually decreases as going axially outward are provided at both axial ends of the convex portions 65a and 65b of the punch 65. In this way, as shown in FIG. 4, taper portions 46a and 46b whose inner diameter gradually decreases as going axially outward are formed at both axial ends of the concave portion 45 of the outer can 16. A curved surface portion may be interposed between the taper portions 46a and 46b and the bottom portion 47 of the concave portion 45. By providing the taper portions 64a and 64b on the punch 65, the punch 65 can be easily removed from the cylindrical member 71. Further, by forming the taper portions 46a and 46b on the outer can 16, even when there is a variation in the axial sticking position of the tape 39 with respect to the electrode body 14, damage to the electrode body 14 caused by the edge of the tape 39 can be effectively suppressed.

Example

[0042] [Example 1] (Fabrication of Positive Electrode) As the positive electrode active material, a lithium nickel composite oxide represented by LiNi 0.88 Co 0.09 Al 0.03 O2 was used. 1 part by mass of acetylene black as a carbon conductive agent and 0.9 part by mass of polyvinylidene fluoride as a binder were mixed with 100 parts by mass of this positive electrode active material, and further, 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 and dried and rolled to fabricate a positive electrode.

[0043] (Fabrication of the negative electrode) Graphite powder was mixed so that it would be 95 parts by mass, and silicon oxide was 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 negative electrode current collector made of copper foil, and dried and rolled to fabricate a negative electrode.

[0044] (Fabrication of the electrode body) The positive electrode and the negative electrode were wound through a separator made of a microporous polyethylene film to fabricate an electrode body with the negative electrode positioned on the outermost periphery. Also, an exposed portion where the copper foil, which is the negative electrode current collector, is exposed was provided on the outer peripheral surface of the outermost peripheral negative electrode. Further, a negative electrode lead was welded to the starting side of the winding of the negative electrode, and the end portion of the outermost peripheral exposed portion was fixed with a tape. As the tape, one with a thickness of 0.03 mm and a width of 9 mm was used. As the positive electrode lead, an aluminum lead was used, and as the negative electrode lead, a nickel lead was used.

[0045] (Fabrication of the outer can) The outer can was made by punching a nickel-plated steel sheet into a circular shape and fabricating a bottomed cylindrical can by the DI method. At this time, using a punch having the shape shown in Fig. 3, the outer diameter of the punch at the portion facing the tape adhered to the outermost periphery of the electrode body was set larger by the thickness of the tape. Thereby, a concave portion was provided on the inner peripheral surface of the outer can. Also, the above-mentioned tapered portion and curved surface portion were provided in the concave portion of the outer can. The width of the bottom of the concave portion was 9 mm, and the depth of the concave portion was 0.03 mm.

[0046] (Preparation of the non-aqueous electrolyte) 5 parts by mass of vinylene carbonate (VC) was added to 80 parts by mass of a mixed solvent (volume ratio EC:DMC = 1:3) composed of ethylene carbonate (EC) and dimethyl methyl carbonate (DMC), and LiPF6 was dissolved at 1.5 mol / liter to prepare a non-aqueous electrolyte.

[0047] (Fabrication of the cylindrical battery) A cylindrical non-aqueous electrolyte secondary battery was fabricated using the above electrode body, outer can, and non-aqueous electrolyte. The tape of the electrode body was housed in the concave portion of the outer can.

[0048] [Example 2] A cylindrical battery of Example 2 was fabricated in the same manner as in Example 1, except that the depth of the concave portion of the outer can was set to 0.024 mm.

[0049] [Example 3] A cylindrical battery of Example 3 was fabricated in the same manner as in Example 1, except that the depth of the concave portion of the outer can was set to 0.036 mm.

[0050] [Comparative Example] A cylindrical battery of the comparative example was fabricated in the same manner as in Example 1, except that the outer can was not provided with a concave portion.

[0051] [Cycle Test] Each of the fabricated cylindrical batteries was charged at a constant current of 0.5It until it reached 4.2 V, and then charged at a constant voltage of 4.2 V until the current value reached 0.05It. Also, it was discharged at a constant current of 0.5It until the voltage reached 2.5 V. After repeating this charge-discharge cycle 100 times, the battery was disassembled, and the presence or absence of deformation due to the edge of the tape in the electrode body was visually confirmed. The results are shown in Table 1.

[0052]

Table 1

[0053] As shown in Table 1, in the comparative example where the concave portion was not provided at the location on the outer can that radially opposed the tape, deformation due to the axial edge of the tape in the electrode body was confirmed. On the other hand, in Examples 1 to 3 where the concave portion was provided at the location on the outer can that radially opposed the tape, deformation due to the axial edge of the tape in the electrode body was not observed. From this, it can be seen that providing a concave portion at the location on the outer can that radially opposed the tape can suppress damage due to the edge of the tape in the electrode body.

[0054] In the above embodiment, the presence or absence of deformation of the electrode body was confirmed when the depth of the concave portion was 80% or more and 120% or less of the thickness of the tape. However, no matter what the dimension of the depth of the concave portion provided at the portion of the tape facing the radial direction in the outer can is, at least a part of the thickness portion of the tape corresponding to the depth can be accommodated in the concave portion, and the stress generated in the electrode body due to the edge of the tape can be reduced. Therefore, when a concave portion is provided at the portion of the tape facing the radial direction in the outer can, damage caused by the edge of the tape in the electrode body can be suppressed regardless of the value of the depth dimension of the concave portion.

[0055] Further, the present disclosure is not limited to the above-described embodiment and its modified examples, and various improvements and changes can be made within the scope of the matters described in the claims of the present application and their equivalent scope.

[0056] For example, in the above embodiment, the case where the tape 39 is arranged at both axial ends of the electrode body 14 has been described. However, the tape may be arranged only at one axial end of the electrode body. Or, the tape may be fixed in a range including the central portion in the axial direction of the electrode body. For example, the tape may be arranged only at the central portion in the axial direction of the electrode body.

[0057] Also, the case where the tape 39 is arranged over the entire circumference in the circumferential direction of the outermost periphery of the electrode body 14 and the tape 39 is accommodated in the annular concave portion 45 provided on the inner circumferential surface of the outer can 16 has been described. However, as shown in FIG. 5, that is, the schematic diagram corresponding to FIG. 2 in the cylindrical battery 110 of the modified example, the tape 139 may be arranged only on a part of the circumferential direction including the terminal end portion at the outermost periphery of the electrode body 14. Further, in that case, a non-annular concave portion 145 may be provided in a region including the portion facing the tape 139 on the inner circumferential surface of the outer can 116. And at least a part of the tape 139 in the thickness direction may be accommodated in the concave portion 145. Such a concave portion 145 can be easily formed by providing a non-annular convex portion on the punch used in the DI method for manufacturing the outer can 116.

Description of Reference Numerals

[0058] 10,110 cylindrical battery, 11 positive electrode, 12 negative electrode, 13 separator, 14 electrode body, 16,116 outer can, 17 sealing body, 20 positive electrode lead, 21 negative electrode lead, 28 gasket, 30 bottomed cylindrical portion, 32 negative electrode current collector, 33 exposed portion, 34 grooved portion, 38 shoulder portion, 39,139 tape, 39a first tape portion, 39b second tape portion, 42 outermost peripheral surface, 45,145 recess, 45a first recess, 45b second recess, 46a,46b tapered portion, 47 bottom, 60,61 mold, 62 steel plate, 64a,64b tapered portion, 65 punch, 65a,65b convex portion, 68 bottom, 71 cylindrical member, 85,86,87 die.

Claims

1. An electrode body in which a long positive electrode and a long negative electrode are wound with a separator interposed therebetween, A bottomed cylindrical exterior can for housing the electrode body, and The electrode body has a tape for fixing the end portion of the electrode body, A recess is provided at least at a position facing the tape on the inner peripheral surface of the exterior can, A cylindrical battery in which at least a part in the thickness direction of the tape is housed in the recess.

2. The cylindrical battery according to claim 1, wherein the recess is provided over the entire circumference on the inner peripheral surface.

3. 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 where at least a part of the negative electrode current collector is exposed is arranged on at least a part of the outermost peripheral surface of the electrode body, The cylindrical battery according to claim 1 or 2, wherein at least a part of the exposed portion is in contact with the inner peripheral surface.

4. The cylindrical battery according to claim 3, wherein the tape is composed of a first tape portion arranged at a first end portion of the electrode body in the axial direction of the cylindrical battery and a second tape portion arranged at a second end portion of the electrode body in the axial direction.

5. The cylindrical battery according to any one of claims 1 to 4, wherein an end portion of the recess on the opening side of the exterior can in the axial direction of the cylindrical battery has a tapered shape in which the inner diameter becomes smaller as it goes toward the opening side in the axial direction.

6. The cylindrical battery according to any one of claims 1 to 5, wherein the recess has a depth of 80% or more and 120% or less of the thickness of the tape.

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