Cylindrical battery

Abstract

This cylindrical battery comprises: a winding-type electrode body (14); an outer can that has a bottomed cylindrical shape and that accommodates the electrode body (14); and a sealing body that closes the opening of the outer can, wherein a plurality of positive electrode leads connected to a positive electrode (11) of the electrode body (14) are included. The plurality of positive electrode leads include a main lead (20a) and two or more sub leads (20b, 20c). The main lead (20a) is connected to the sealing body, and the sub leads (20b, 20c) are connected to the main lead (20a) at a location away from the connection part between the main lead (20a) and the sealing body.

Description

Cylindrical battery

[0001] The present disclosure relates to cylindrical batteries, and more particularly to cylindrical batteries having an electrode assembly including multiple positive electrode leads.

[0002] A cylindrical battery generally includes a wound electrode assembly, a cylindrical outer can with a bottom that houses the electrode assembly, and a sealing member that closes the opening of the outer can. A positive electrode lead extending from the positive electrode of the electrode assembly is connected to the sealing member or the outer can. In recent years, cylindrical batteries have been widely used in applications requiring high capacity, high output, high durability, etc., such as in-vehicle applications and power storage applications. To improve the output characteristics of the battery, a cylindrical battery with multiple positive electrode leads that connect each of the positive electrode and the sealing member has also been proposed (see, for example, Patent Document 1).

[0003] Japanese Patent Application Laid-Open No. 2001-176489

[0004] In cylindrical batteries, for example, if an external short circuit occurs while the battery is in a charged state, a large current may be applied to the electrode body, potentially causing the electrode body to overheat abnormally. In particular, in cylindrical batteries with multiple positive electrode leads, the application of a large current is likely to continue in the event of an abnormality, which is likely to result in a large amount of heat being generated by the electrode body.

[0005] The cylindrical battery according to the present disclosure is a cylindrical battery comprising a wound electrode body, a cylindrical outer can with a bottom that houses the electrode body, and a sealing body that closes the opening of the outer can, and including a plurality of positive electrode leads connected to the positive electrode of the electrode body, wherein the plurality of positive electrode leads include a main lead and two or more sub-leads, the main lead is connected to the sealing body, and the sub-leads are connected to the main lead at a position away from the connection between the main lead and the sealing body.

[0006] According to the cylindrical battery of the present disclosure, in a battery equipped with an electrode assembly including multiple positive electrode leads, the electrical connection between the electrode assembly and an external circuit can be quickly cut off in the event of an abnormality, thereby suppressing heat generation in the electrode assembly in the event of an abnormality.

[0007] Fig. 1 is a cross-sectional view of a cylindrical battery that is an example of an embodiment; Fig. 2 is a perspective view of an electrode body that is an example of an embodiment; Fig. 3 is a perspective view of an electrode body that is another example of an embodiment; Fig. 4 is a perspective view of an electrode body that is another example of an embodiment; Fig. 5 is a perspective view of an electrode body that is another example of an embodiment; Fig. 6 is a perspective view of an electrode body that is another example of an embodiment.

[0008] An embodiment of a cylindrical battery according to the present disclosure will be described in detail with reference to the drawings.

[0009] Fig. 1 is a cross-sectional view of a cylindrical battery 10 according to an embodiment. As shown in Fig. 1, the cylindrical battery 10 includes a wound electrode assembly 14, an electrolyte, a cylindrical outer can 16 with a bottom that houses the electrode assembly 14 and the electrolyte, and a sealing member 17 that closes the opening of the outer can 16. The electrode assembly 14 includes a positive electrode 11, a negative electrode 12, and a separator 13, and has a wound structure in which the positive electrode 11 and the negative electrode 12 are spirally wound with the separator 13 interposed therebetween. Hereinafter, for convenience of explanation, the sealing member 17 side of the battery will be referred to as the top, and the bottom side of the outer can 16 will be referred to as the bottom.

[0010] The positive electrode 11, negative electrode 12, and separator 13 that constitute the electrode assembly 14 are all long, strip-like bodies that are spirally wound and alternately stacked in the radial direction of the electrode assembly 14. The negative electrode 12 is formed to be slightly larger than the positive electrode 11 in order to prevent lithium deposition. That is, the negative electrode 12 is formed to be longer than the positive electrode 11 in the longitudinal and width directions. The separator 13 is formed to be at least slightly larger than the positive electrode 11, and, for example, two separators 13 are arranged to sandwich the positive electrode 11. The electrode assembly 14 has a positive electrode lead connected to the positive electrode 11 by welding or the like, and a negative electrode lead 21 connected to the negative electrode 12 by welding or the like.

[0011] As will be described in more detail below, the cylindrical battery 10 includes multiple positive electrode leads. The multiple positive electrode leads include a main lead 20a and two or more sub-leads 20b and 20c. The main lead 20a is connected to the outer can 16 or the sealing body 17, and the sub-leads 20b and 20c are connected to the main lead 20a at positions away from the connection between the main lead 20a and the outer can 16 or the sealing body 17. In this embodiment, the main lead 20a is connected to the sealing body 17, and in the event of an abnormality, the main lead 20a melts and breaks the electrical connection between the positive electrode 11 and the sealing body 17.

[0012] The positive electrode 11 has a positive electrode core and a positive electrode mixture layer disposed on the positive electrode core. The positive electrode core can be a foil of a metal that is stable within the potential range of the positive electrode 11, such as aluminum, an aluminum alloy, stainless steel, or titanium, or a film with such a metal disposed on the surface. The positive electrode mixture layer contains a positive electrode active material, a conductive agent, and a binder, and is preferably provided on both sides of the positive electrode core except for the portion where the positive electrode lead is connected. The positive electrode active material is a lithium transition metal composite oxide containing a transition metal element such as Ni, Co, or Mn.

[0013] The negative electrode 12 has a negative electrode core and a negative electrode mixture layer disposed on the negative electrode core. The negative electrode core can be a foil of a metal stable within the potential range of the negative electrode 12, such as copper, a copper alloy, stainless steel, nickel, or a nickel alloy, or a film having such a metal disposed on its surface. The negative electrode mixture layer contains a negative electrode active material and a binder, and is preferably provided on both sides of the negative electrode core except for the portion to which the negative electrode lead 21 is connected. The negative electrode active material generally uses a carbon material that reversibly absorbs and releases lithium ions. The negative electrode active material may also use an element that alloys with Li, such as Si or Sn, or a material containing such an element.

[0014] 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. Suitable materials for the separator 13 include polyolefins such as polyethylene and polypropylene, and cellulose. The separator 13 may have a single-layer structure or a multi-layer structure. The separator 13 may have, for example, a multi-layer structure including a thermoplastic resin layer such as polyolefin and a cellulose fiber layer, a two-layer structure of polyethylene (PE) / polypropylene (PP), or a three-layer structure of PE / PP / PE.

[0015] The electrolyte may be an aqueous electrolyte, but in this embodiment, a non-aqueous electrolyte is used. The non-aqueous electrolyte has lithium ion conductivity. The non-aqueous electrolyte may be a liquid electrolyte (electrolytic solution) or a solid electrolyte.

[0016] The liquid electrolyte (electrolytic solution) contains 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. Examples of the electrolyte salt include LiPF ６ Lithium salts such as

[0017] As the solid electrolyte, for example, a solid or gel-like polymer electrolyte, an inorganic solid electrolyte, etc. can be used. As the inorganic solid electrolyte, a material known in all-solid-state lithium ion secondary batteries, etc. (for example, an oxide-based solid electrolyte, a sulfide-based solid electrolyte, a halogen-based solid electrolyte, etc.) can be used. 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. As the matrix polymer, for example, a polymer material that absorbs a non-aqueous solvent and gels is used. As the polymer material, for example, a fluororesin, an acrylic resin, a polyether resin, etc. can be used.

[0018] Insulating plates 18 and 19 are disposed above and below the electrode body 14. In the example shown in FIG. 1 , the positive electrode lead passes through a through hole in the insulating plate 18 and extends toward the sealing body 17, and the negative electrode lead 21 passes outside the insulating plate 19 and extends toward the bottom of the outer can 16. Of the multiple positive electrode leads, a main lead 20a is connected to the underside of an internal terminal plate 23 of the sealing body 17 by welding or the like, and a cap 27, which is the top plate of the sealing body 17 and is electrically connected to the internal terminal plate 23, serves as the positive electrode terminal. The negative electrode lead 21 is connected to the inner bottom surface of the outer can 16 by welding or the like, and the outer can 16 serves as the negative electrode terminal. The outer can 16 and the sealing body 17 are connected to an external circuit, for example, another battery constituting the battery module, a charger, or the like.

[0019] The outer can 16 is a cylindrical metal container with a bottom and an opening on one axial side, and the opening of the outer can 16 is closed by a sealing body 17. A gasket 28 is provided between the outer can 16 and the sealing body 17 to ensure airtightness inside the battery. The outer can 16 has a grooved portion 22 that supports the sealing body 17, with part of the side surface protruding inward. The grooved portion 22 is preferably formed in an annular shape along the circumferential direction of the outer can 16, and supports the sealing body 17 on its top surface. The sealing body 17 is fixed to the top of the outer can 16 by the grooved portion 22 and the open end of the outer can 16 that is crimped to the sealing body 17.

[0020] The sealing body 17 has a structure in which, in order from the electrode body 14 side, an internal terminal plate 23, a lower valve body 24, an insulating member 25, an upper valve body 26, and a cap 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 one another. The lower valve body 24 and the upper valve body 26 are connected at their respective centers, and the insulating member 25 is interposed between their respective peripheral edges. When the internal pressure of the battery increases due to abnormal heat generation, the lower valve body 24 deforms and breaks, pushing the upper valve body 26 toward the cap 27, thereby interrupting the current path between the lower valve body 24 and the upper valve body 26. When the internal pressure further increases, the upper valve body 26 breaks, and gas is discharged from the opening of the cap 27.

[0021] The configuration of the electrode assembly 14, particularly the configuration of the positive electrode lead, will be described in detail below with further reference to Fig. 2. Fig. 2 is a perspective view of the electrode assembly 14.

[0022] As shown in Figures 1 and 2, the electrode assembly 14 includes one main lead 20a and two sub-leads 20b, 20c as positive electrode leads connected to the positive electrode 11. The positive electrode lead extends from the upper end of the electrode group 14a constituting the electrode assembly 14 toward the sealing body 17, and the main lead 20a is connected to an internal terminal plate 23 of the sealing body 17. The electrode group 14a refers to a wound body consisting of the positive electrode 11, negative electrode 12, and separator 13, and a hollow portion 29 is formed in the winding core. In the cylindrical battery 10, only the main lead 20a is directly connected to the sealing body 17. The sub-leads 20b, 20c are electrically connected to the sealing body 17 via the main lead 20a.

[0023] The sub-leads 20b, 20c are not directly connected to the sealing body 17, but are connected to the main lead 20a at a position away from the connection between the main lead 20a and the sealing body 17. In this embodiment, the main lead 20a is welded to the internal terminal plate 23 of the sealing body 17, and the sub-leads 20b, 20c are welded to the main lead 20a. As will be described in detail later, a second weld 32 which is the connection between the main lead 20a and the sub-leads 20b, 20c is formed above the hollow portion 29 of the electrode group 14a, away from the first weld 31 which is the connection between the main lead 20a and the sealing body 17.

[0024] A current path is formed only by the main lead 20a between the first welded portion 31 between the main lead 20a and the sealing body 17 and the second welded portion 32 between the main lead 20a and the sub-leads 20b and 20c. The portion of the main lead 20a located between the welded portions 31 and 32 is referred to as a first region R1, and the portion of the main lead 20a located closer to the positive electrode 11 than the welded portion 32 is referred to as a second region R2.

[0025] Assuming an external short circuit occurs while the cylindrical battery 10 is in a charged state, the short-circuit current will be shunted to multiple positive electrode leads, but because the short-circuit current is shunted closer to the positive electrode 11 than the welded portion 31, a large current will be applied to the first region R1 of the main lead 20a. This causes the first region R1 of the main lead 20a to heat up and melt, cutting off the electrical connection between the positive electrode 11 and the sealing body 17. The cylindrical battery 10 has multiple positive electrode leads and is structured to shunt the short-circuit current, but by providing a portion of the positive electrode lead where the short-circuit current concentrates (first region R1), the electrical connection between the electrode body 14 and the external circuit is quickly cut off in the event of an abnormality, effectively suppressing heat generation in the electrode body 14.

[0026] The main lead 20a and the sub-leads 20b, 20c are strip-shaped conductive members, and are made of, for example, a metal containing aluminum as a main component. The positive electrode lead is preferably made of an aluminum alloy. The aluminum alloy is an alloy to which one or more other metal elements, such as copper, manganese, silicon, magnesium, zinc, or nickel, are added. By adjusting the type and amount of the added element, the electrical resistance, hardness, etc. of the material can be changed. The main lead 20a and the sub-leads 20b, 20c may be made of the same material or different materials.

[0027] When the main lead 20a and the sub-leads 20b, 20c are made of different materials, the main lead 20a is made of, for example, a material with a higher electrical resistance than the sub-leads 20b, 20c. By making the electrical resistance of the main lead 20a higher than the electrical resistance of the sub-leads 20b, 20c, the first region R1 of the main lead 20a is more likely to melt when a battery abnormality occurs and a large current is applied, allowing the current path to the external circuit to be cut off more quickly. Note that the sub-leads 20b, 20c are preferably made of the same material.

[0028] One example of a method for making the electrical resistance of the main lead 20a greater than the electrical resistance of the sub-leads 20b, 20c is to lower the aluminum purity of the aluminum alloy constituting the main lead 20a than the aluminum purity of the aluminum alloy constituting the sub-leads 20b, 20c. The electrical resistance of the main lead 20a is adjusted, for example, to be 1.1 to 3.0 times, or 1.2 to 2.0 times, the electrical resistance of the sub-leads 20b, 20c. In this case, heat generation in the main lead 20a during normal battery use can be suppressed, while the current path can be quickly shut off in the event of an abnormality.

[0029] When the main lead 20a and the sub-leads 20b and 20c are made of different materials, the main lead 20a is made of, for example, a material having a higher hardness than the sub-leads 20b and 20c. Since the sub-leads 20b and 20c are welded to the main lead 20a and there are many bending portions as described below, the main lead 20a is preferably stronger than the sub-leads 20b and 20c. The main lead 20a may have a higher resistance and a higher hardness (higher strength) than the sub-leads 20b and 20c. The hardness of the positive electrode lead is measured by Vickers hardness measurement.

[0030] One example of a method for making the hardness of the main lead 20a greater than the hardness of the sub-leads 20b, 20c is to lower the aluminum purity of the aluminum alloy constituting the main lead 20a than the aluminum purity of the aluminum alloy constituting the sub-leads 20b, 20c. From the viewpoint of ensuring the mechanical strength of the main lead 20a, the hardness of the main lead 20a is adjusted to, for example, 1.1 to 4.0 times, or 1.2 to 3.0 times, the hardness of the sub-leads 20b, 20c.

[0031] The positive electrode lead is welded to the core of the positive electrode 11. The positive electrode 11 has a plurality of core exposed portions spaced apart in the longitudinal direction of the positive electrode 11, where the positive electrode mixture layer is not present on the positive electrode core and the surface of the positive electrode core is exposed. One positive electrode lead is connected to each exposed portion by welding or the like. The positive electrode lead is generally joined to only one side of the positive electrode core, but the core exposed portions are provided on both sides of the positive electrode 11. The core exposed portions are formed, for example, with substantially the same size so as to overlap in the thickness direction of the positive electrode 11. The welding position of the positive electrode lead at each exposed portion is not particularly limited, and the positive electrode lead is arranged within the range of the core exposed portion so as not to overlap with the positive electrode mixture layer.

[0032] In this embodiment, a total of three positive electrode leads, the main lead 20a and the sub-leads 20b and 20c, are provided, so that exposed core portions are formed at three locations spaced apart along the length of the positive electrode 11. The spacing between each exposed portion may be constant or may vary. However, for example, the layout of the positive electrode leads is appropriately set depending on the battery performance of the cylindrical battery 10, such as the capacity and output characteristics, and therefore the spacing between each exposed core portion is determined depending on the layout, etc. The number of positive electrode leads may be three or more, and may be, for example, four to fifteen or six to ten. Two or more main leads may be connected to the sealing body 17, but one is preferred from the viewpoint of quickly interrupting the current path.

[0033] The main lead 20a passes through a through hole in the insulating plate 18 and extends toward the sealing body 17, and is bent so as to fit along the upper surface of the insulating plate 18. The tip of the main lead 20a is bent back so as to fit along the lower surface of the internal terminal plate 23. In this embodiment, the main lead 20a has a first bent portion 41 near the positive electrode 11 and a second bent portion 42 near the sealing body 17. The main lead 20a is disposed closer to the outer periphery of the electrode body 14 than the sub-leads 20b and 20c, and is longer than the sub-leads 20b and 20c. The sub-leads 20b and 20c are bent back so as to fit along the upper surface of the insulating plate 18, but their tips are not bent back like the main lead 20a.

[0034] In the main lead 20a, the first weld 31 to the sealing body 17 is formed closer to the tip than the second bent portion 42, and the second weld 32 to the sub-leads 20b, 20c is formed between the bent portions 41, 42. Note that although the second weld 32 is formed in one location, it is possible to weld the sub-leads 20b, 20c to different locations on the main lead 20a. However, even in this case, each weld is formed so that the weld 31 to the sealing body 17 and the weld 32 to the sub-leads 20b, 20c do not come into contact with each other. The first region R1 of the main lead 20a has a length that is, for example, 10% or more of the length of the portion extending from the electrode group 14a.

[0035] As described above, the electrode body 14 has a hollow portion 29 formed in the winding core. The hollow portion 29 is a space extending in the axial direction of the electrode group 14a. The welded portion 32 of the sub-leads 20b, 20c to the main lead 20a is located, for example, above the hollow portion 29 of the electrode group 14a. That is, the hollow portion 29 and the welded portion 32 overlap in the axial direction of the electrode body 14. In this case, the welded portion 32 can be formed by inserting a jig used for welding into the hollow portion 29. As a result, a good welded portion 32 can be easily formed, and the reliability of the welded portion 32 is also improved. For example, in a plan view of the electrode body 14, the entire area of ​​the welded portion 32 overlaps with the hollow portion 29, or at least a portion of the welded portion 32 overlaps with the hollow portion 29.

[0036] The sub-leads 20b, 20c are welded while being disposed on the main lead 20a. That is, the sub-leads 20b, 20c are disposed closer to the sealing body 17 than the main lead 20a at the welded portion 32. In this case, welding is facilitated and the reliability of the welded portion 32 is improved. In this embodiment, the sub-lead 20b is disposed on the main lead 20a, and the sub-lead 20c is disposed on the sub-lead 20b at the welded portion 32. When the width of the sub-lead 20b is, for example, approximately the same as that of the sub-leads 20b, 20c, it is preferable to overlap and weld the sub-leads 20b, 20c to each other from the viewpoint of welding stability, etc.

[0037] In this embodiment, all positive electrode leads have substantially the same width, but as described below, the widths of the main lead and the sub-leads may be different. Note that it is preferable that the sub-leads have substantially the same width. For example, when the width of the main lead 20a is large, the sub-lead 20c may be disposed directly on the main lead 20a without overlapping with the sub-lead 20b, and one weld 32 including the tip ends of the sub-leads 20b and 20c may be formed.

[0038] Another example of the embodiment will be described below with reference to Figures 3 to 6. Below, the same components as those in the above embodiment are designated by the same reference numerals, and redundant description will be omitted. Note that the configurations of all the embodiments are the same except for the positive electrode lead.

[0039] The electrode body 50 illustrated in FIG. 3 differs from the electrode body 14 in that the widthwise cross-sectional area of ​​the main lead 51 is larger than the widthwise cross-sectional area of ​​the sub-leads 20b and 20c. In this case, heat generation in the main lead 51 during normal use of the battery can be suppressed. Although the widthwise cross-sectional area of ​​the main lead 51 can be increased by making it thicker than the sub-leads 20b and 20c, it is preferable to increase the widthwise cross-sectional area. Using a main lead 51 that is wider than the sub-leads 20b and 20c not only suppresses heat generation during normal use, but also makes it easier to weld the sub-leads 20b and 20c, improving the reliability of the welded portion 32.

[0040] The width of the main lead 51 is, for example, 1.2 to 4.0 times, or 1.3 to 3.0 times, or 1.4 to 2.0 times the width of the sub-leads 20b, 20c. If the ratio of the width of the main lead 51 to the width of the sub-leads 20b, 20c is within this range, the above-mentioned effect can be ensured during normal battery use while quickly interrupting the current path in the event of an abnormality. Note that the preferred width of the electrode lead varies depending on the battery capacity, size, etc., but is, for example, 3 mm to 25 mm.

[0041] The electrode assembly 60 illustrated in FIG. 4 differs from the electrode assembly 14 in that it includes two main leads 61, each of which is arranged overlapping one another. In this case, the mechanical strength of the main lead 61 is improved, and the widthwise cross-sectional area of ​​the main lead 61 is larger than the widthwise cross-sectional area of ​​the sub-leads 20b and 20c, thereby achieving the same effect as in the electrode assembly 50. In the example illustrated in FIG. 4, the two main leads 61 extend from positions radially spaced apart and aligned radially from the electrode group 60a. It is also possible to connect the two main leads 61 to the front and back of a single positive electrode core, sandwiching the core body between them.

[0042] The electrode body 70 illustrated in Fig. 5 differs from the electrode body 14 in that the widthwise cross-sectional area of ​​the main lead 71 is smaller than the widthwise cross-sectional area of ​​the sub-leads 20b, 20c. In this case, the current path can be cut off more quickly in the event of a battery abnormality. Although the widthwise cross-sectional area of ​​the main lead 71 can be reduced by making it thinner than the sub-leads 20b, 20c, in the example illustrated in Fig. 5, the widthwise cross-sectional area is reduced by making it thinner.

[0043] The width of the main lead 71 is, for example, 0.50 to 0.95 times, or 0.60 to 0.90 times, or 0.70 to 0.90 times the width of the sub-leads 20b and 20c. The ratio of the width of the main lead 71 to the width of the sub-leads 20b and 20c is determined in consideration of the welding stability of the sub-leads 20b and 20c, suppression of heat generation in the main lead 71 during normal use, and rapid melting of the main lead 71 in the event of an abnormality.

[0044] The electrode assembly 80 illustrated in FIG. 6 includes six sub-leads 81b to 81g, and differs from the electrode assembly 14 in that the main lead 81a is wider than the sub-leads 81b to 81g. The widths of the six sub-leads 81b to 81g are substantially the same. The electrode assembly 80 includes a total of seven positive electrode leads, but as described above, the number of positive electrode leads may be eight or more. In addition, the main lead 81a extends radially inward of the electrode group 80a relative to the sub-leads 81b to 81g.

[0045] The width of the main lead 81a is, for example, 1.2 to 4.0 times, or 1.3 to 3.0 times, or 1.4 to 2.0 times the width of the sub-leads 81b to 81g, as in the case of the electrode body 50. In the example shown in Fig. 6, six sub-leads 81b to 81g are arranged in pairs, overlapping each other. The pairs of sub-leads are arranged close to each other on the main lead 81a without overlapping, and are connected to the main lead 81a by a single weld 32 formed above the hollow portion 29 of the electrode group 80a.

[0046] The above-mentioned pair of sub-leads can be connected to the front and back of a single positive electrode core body by sandwiching the core body between them, but it is preferable that the two sub-leads extend from positions that are radially spaced apart from each other and aligned radially on the electrode group 80a, as shown in Figure 6.

[0047] As described above, the cylindrical battery of the above embodiment has an electrode assembly including multiple positive leads, and therefore exhibits good output characteristics during normal use. Meanwhile, with the cylindrical battery of the above embodiment, in the event of an abnormality, the first region of the main lead heats up and melts, quickly cutting off the electrical connection between the electrode assembly and the external circuit. As a result, heat generation in the electrode assembly during an abnormality is effectively suppressed.

[0048] The above-described embodiments may be appropriately modified without departing from the scope of the present disclosure, and may be modified by selectively combining the components of the above-described embodiments. For example, in the embodiment illustrated in Fig. 6, the width of the main lead may be the same as the width of the sub-lead, or two main leads may be used as in the embodiment illustrated in Fig. 4.

[0049] The present disclosure is further described by the following embodiments. Configuration 1: A cylindrical battery comprising a wound 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, and including multiple positive electrode leads connected to the positive electrode of the electrode assembly, wherein the multiple positive electrode leads include a main lead and two or more sub-leads, the main lead is connected to the sealing body, and the sub-leads are connected to the main lead at a position away from the connection between the main lead and the sealing body. Configuration 2: The cylindrical battery according to Configuration 1, wherein the widthwise cross-sectional area of ​​the main lead is larger than the widthwise cross-sectional area of ​​the sub-leads. Configuration 3: The cylindrical battery according to Configuration 1, wherein the widthwise cross-sectional area of ​​the main lead is smaller than the widthwise cross-sectional area of ​​the sub-leads. Configuration 4: The cylindrical battery according to any one of Configurations 1 to 3, wherein the main lead has a higher electrical resistance than the sub-leads. Configuration 5: The cylindrical battery according to any one of Configurations 1 to 4, wherein the main lead has a higher hardness than the sub-leads. The cylindrical battery of any one of the preceding claims, wherein the electrode assembly has a hollow portion formed in a winding core, and the connection portion of the sub-lead to the main lead is located above the hollow portion. The cylindrical battery of any one of the preceding claims, wherein the main lead is connected to the sealing body, and the sub-lead is located closer to the sealing body than the main lead at the connection portion of the sub-lead to the main lead.

[0050] REFERENCE SIGNS LIST 10 Cylindrical battery, 11 Positive electrode, 12 Negative electrode, 13 Separator, 14 Electrode body, 14a Electrode group, 16 Outer can, 17 Sealing body, 18, 19 Insulating plate, 20a Main lead, 20b, 20c Sub-lead, 21 Negative electrode lead, 22 Grooved portion, 23 Internal terminal plate, 24 Lower valve body, 25 Insulating member, 26 Upper valve body, 27 Cap, 28 Gasket, 29 Hollow portion, 31, 32 Welded portion, 41, 42 Bent portion, R1 First region, R2 Second region

Claims

1. A cylindrical battery comprising a wound-type electrode body, a cylindrical outer can with a bottom that houses the electrode body, and a sealing body that closes the opening of the outer can, and including a plurality of positive electrode leads connected to the positive electrode of the electrode body, wherein the plurality of positive electrode leads include a main lead and two or more sub-leads, the main lead is connected to the sealing body, and the sub-leads are connected to the main lead at a position away from the connection between the main lead and the sealing body.

2. The cylindrical battery according to claim 1, wherein the cross-sectional area in the width direction of the main lead is larger than the cross-sectional area in the width direction of the sub-lead.

3. The cylindrical battery according to claim 1, wherein the cross-sectional area in the width direction of the main lead is smaller than the cross-sectional area in the width direction of the sub-lead.

4. The cylindrical battery according to any one of claims 1 to 3, wherein the main lead has a higher electrical resistance than the sub-lead.

5. The cylindrical battery according to any one of claims 1 to 3, wherein the main lead has a harder hardness than the sub-lead.

6. A cylindrical battery as described in any one of claims 1 to 3, wherein the electrode body has a hollow portion formed in a winding core, and the connection portion of the sub-lead to the main lead is located above the hollow portion.

7. A cylindrical battery according to any one of claims 1 to 3, wherein the main lead is connected to the sealing body, and at the connection portion of the sub-lead to the main lead, the sub-lead is positioned closer to the sealing body than the main lead.

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