Cylindrical battery

Abstract

The present invention provides a cylindrical battery in which the opening end of an outer can has a different polarity from a sealing body and is easily connectable to an external lead. A cylindrical battery (10) that is one embodiment described in the present disclosure comprises: an electrode body (14) that includes a positive electrode (11) and a negative electrode (12); a bottomed cylindrical outer can (16) that houses the electrode body (14) and is connected to one of the positive electrode (11) and the negative electrode (12); and a sealing body (17) that is connected to the other of the positive electrode (11) and the negative electrode (12). The outer can (16) has a protrusion (16a) formed by the side surface thereof protruding radially inward, and an opening end (16b) extends radially outward. The sealing body (17) is fixed by crimping radially inward of the protrusion (16a) with a gasket (18) interposed therebetween.

Description

[Technical Field]

[0001] The present disclosure relates to cylindrical batteries. [Background technology]

[0002] Cylindrical batteries have been widely known in which an electrode assembly is housed in a cylindrical outer can with a bottom, and the opening of the outer can is sealed with a sealing body (see, for example, Patent Documents 1 and 2). Generally, the outer can has a grooved portion where a portion of the side surface protrudes inward, and the open end of the outer can is bent inward. A gasket interposed between the grooved portion and the open end is compressed vertically to crimp and secure the sealing body. Furthermore, a positive electrode lead and a negative electrode lead protrude from the positive electrode and negative electrode, respectively, included in the electrode assembly. For example, the sealing body is connected to the positive electrode lead to form a positive electrode external terminal, and the outer can is connected to the negative electrode lead to form a negative electrode external terminal. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-152031 [Patent Document 2] Special Publication No. 2010-512638 Summary of the Invention [Problem to be solved by the invention]

[0004] When connecting multiple cylindrical batteries to form a battery module, external leads are connected to each of the sealing body and the outer can, and the multiple cylindrical batteries are connected to each other via the external leads. To shorten the connection distance between batteries, the external leads are sometimes connected to the open end of the outer can located on the sealing body side of one battery and to the sealing body of an adjacent battery. In conventional batteries, the open end of the outer can is short, making it difficult to connect the external leads to the open end. Furthermore, if an attempt is made to improve workability by lengthening the open end, the gasket cannot be uniformly compressed at the open end, resulting in wrinkles and waving, which reduces the flatness of the open end and makes it difficult to stably connect the external leads to the open end serving as an external terminal.

[0005] Therefore, an object of the present disclosure is to provide a cylindrical battery having an external terminal at the open end of the outer can, which has a polarity different from that of the sealing body and can be easily connected to an external lead. [Means for solving the problem]

[0006] A cylindrical battery according to one aspect of the present disclosure comprises an electrode assembly including a positive electrode and a negative electrode, a cylindrical outer can with a bottom that houses the electrode assembly and is connected to one of the positive electrode and the negative electrode, and a sealing body that is connected to the other of the positive electrode and the negative electrode, wherein the outer can has a protrusion that protrudes radially inward on its side and has an open end that extends radially outward, and the sealing body is fixed by crimping to the radially inward by the protrusion via a gasket. [Effects of the Invention]

[0007] In a cylindrical battery according to one aspect of the present disclosure, the open end for connecting an external lead extends radially outward, making it possible to form an open end that is flatter and has a larger area than the open end of the outer can of a conventional cylindrical battery. This allows for the formation of an external terminal at the open end of the outer can that has a polarity different from that of the sealing body and that can be easily connected to an external lead. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a longitudinal cross-sectional view of a cylindrical battery according to an embodiment of the present invention; [Figure 2] FIG. 2 is an enlarged view of a portion of the upper end of the outer can in FIG. [Figure 3] 3 is a diagram showing an embodiment of FIG. 2 further comprising a conductive member joined to the open end. [Figure 4] FIG. 10 is a diagram corresponding to FIG. 2 in another example of the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] An example of an embodiment of a cylindrical battery according to the present disclosure will be described in detail below with reference to the drawings. Figure 1 is a longitudinal cross-sectional view of a cylindrical battery 10 according to an embodiment.

[0010] As shown in FIG. 1 , a cylindrical battery 10 includes an electrode assembly 14, a cylindrical outer can 16 with a bottom that houses the electrode assembly 14 and an electrolyte (not shown), and a sealing body 17 that closes the opening of the outer can 16 via a gasket 18. The electrode assembly 14 includes a positive electrode 11, a negative electrode 12, and a separator 13, and has a structure in which the positive electrode 11 and the negative electrode 12 are spirally wound with the separator 13 interposed therebetween. Note that, for convenience of explanation, the direction along the axial direction of the outer can 16 will be referred to as the "vertical direction or up-down direction," the sealing body 17 side will be referred to as the "top," and the bottom side of the outer can 16 will be referred to as the "bottom." Furthermore, the direction perpendicular to the axial direction of the outer can 16 will be referred to as the "horizontal direction or radial direction," and the radially inner side of the outer can 16 will be referred to as the "inner side," and the radially outer side will be referred to as the "outer side."

[0011] The positive electrode 11 has a positive electrode core and a positive electrode mixture layer formed on at least one surface of the core. The positive electrode core can be a foil of a metal such as aluminum or an aluminum alloy that is stable within the potential range of the positive electrode 11, or a film with such a metal disposed on the surface layer. The positive electrode mixture layer contains a positive electrode active material, a conductive agent such as acetylene black, and a binder such as polyvinylidene fluoride, and is preferably formed on both sides of the positive electrode core. The positive electrode active material can be, for example, a lithium transition metal composite oxide.

[0012] The negative electrode 12 has a negative electrode core and a negative electrode mixture layer formed on at least one surface of the core. The negative electrode core can be made of a foil of a metal such as copper or a copper alloy that is stable within the potential range of the negative electrode 12, or a film with such a metal disposed on the surface layer. The negative electrode mixture layer contains a negative electrode active material and a binder such as styrene-butadiene rubber (SBR), and is preferably formed on both sides of the negative electrode core. The negative electrode active material can be, for example, graphite or a silicon-containing compound.

[0013] The electrolyte may be an aqueous electrolyte or a non-aqueous electrolyte. It may also be a liquid electrolyte or a solid electrolyte. In this embodiment, a non-aqueous electrolyte is used. The non-aqueous electrolyte includes a non-aqueous solvent and an electrolyte salt dissolved in the non-aqueous solvent. Examples of the non-aqueous solvent that can be used include esters, ethers, nitriles, amides, and mixed solvents of two or more of these. The non-aqueous solvent may contain a halogen-substituted compound in which at least a portion of the hydrogen atoms in these solvents are substituted with halogen atoms such as fluorine. The electrolyte salt may be, for example, a lithium salt such as LiPF6.

[0014] The cylindrical battery 10 includes insulating plates 19 and 20 disposed above and below the electrode assembly 14. An outer can 16 is connected to either the positive electrode 11 or the negative electrode 12, and a sealing body 17 is connected to the other of the positive electrode 11 and the negative electrode 12. In the example shown in FIG. 1 , a positive electrode lead 21 connected to the positive electrode 11 passes through a through-hole in the insulating plate 19 and extends toward the sealing body 17, while a negative electrode lead 22 connected to the negative electrode 12 passes outside the insulating plate 20 and extends toward the bottom of the outer can 16. The positive electrode lead 21 is connected by welding or the like to an internal terminal plate 25, which is the bottom plate of the sealing body 17. A rupture plate 26 of the sealing body 17, which is electrically connected to the internal terminal plate 25, serves as a positive electrode external terminal. The negative electrode lead 22 is connected by welding or the like to the inner surface of the bottom of the outer can 16, which serves as a negative electrode external terminal. The negative electrode lead may be connected to the inner surface of sealing body 17, and the positive electrode lead may be connected to the inner surface of outer can 16. In this case, sealing body 17 serves as the negative electrode external terminal, and outer can 16 serves as the positive electrode external terminal.

[0015] The outer can 16 is a metal container that is open at one axial end (top end), has a disk-shaped bottom, and has cylindrical sides that follow the outer periphery of the bottom. The sealing body 17 is formed in a disk shape that corresponds to the shape of the opening of the outer can 16. The gasket 18 is an annular resin member that ensures the sealing of the interior of the battery and ensures electrical insulation between the outer can 16 and the sealing body 17. The sealing body 17 is fixed by crimping via the gasket 18 on the radially inner side of the protruding portion 16a of the outer can 16.

[0016] The exterior can 16 has a protruding portion 16a on its side that protrudes radially inward, and an open end 16b that extends radially outward. The protruding portion 16a functions to crimp and fix the sealing body 17. An external lead is connected to the open end 16b.

[0017] The outer can 16 has a grooved portion 23 that protrudes inward from the side surface. The grooved portion 23 is formed in a ring shape along the circumferential direction of the outer can 16 by spinning from the outside of the side surface. The grooved portion 23 has a generally U-shaped cross section, and its upper surface supports the sealing body 17. The grooved portion 23 supports the sealing body 17 from below, making it easy to align the sealing body 17 during the manufacture of the cylindrical battery 10. Note that the outer can 16 does not necessarily have to have the grooved portion 23. As described below, the protruding portion 16a crimps and fixes the sealing body 17 to the radially inward side, ensuring a tight seal inside the battery even if the outer can 16 does not have the grooved portion 23. If the outer can 16 does not have the grooved portion 23, the space inside the outer can 16 that houses the electrode assembly 14 can be made larger vertically, thereby increasing the capacity of the battery.

[0018] The sealing body 17 is a disc-shaped member equipped with a current interruption mechanism. The sealing body 17 has a structure in which, from the electrode body 14 side, an internal terminal plate 25, an insulating plate 27, and a rupture plate 26 are stacked. The internal terminal plate 25 is a metal plate including an annular portion 25a to which the positive electrode lead 21 is connected and a thin-walled central portion 25b that is separated from the annular portion 25a when the internal pressure of the battery exceeds a predetermined threshold. An air vent 25c is formed in the annular portion 25a.

[0019] Rupture plate 26 is disposed opposite internal terminal plate 25 with insulating plate 27 sandwiched therebetween. Insulating plate 27 has opening 27a formed in its radial center and vent hole 27b formed in a portion overlapping vent hole 25c of internal terminal plate 25. Rupture plate 26 has valve portion 26a that ruptures when the internal pressure of the battery exceeds a predetermined threshold, and valve portion 26a is connected to central portion 25b of internal terminal plate 25 via opening 27a of insulating plate 27 by welding or the like. Insulating plate 27 insulates portions other than the connection portion between annular portion 25a and central portion 25b of valve portion 26a.

[0020] The valve portion 26a is formed in the radial center of the rupture plate 26, including a lower protrusion that protrudes toward the inside of the battery and a thin-walled portion formed around the lower protrusion. In the cylindrical battery 10, the internal terminal plate 25, to which the positive electrode lead 21 is connected, is electrically connected to the rupture plate 26, thereby forming a current path connecting the electrode body 14 to the rupture plate 26. When an abnormality occurs in the battery and the internal pressure increases, the internal terminal plate 25 breaks, the central portion 25b is separated from the annular portion 25a, and the valve portion 26a deforms so that it protrudes upward toward the battery. This interrupts the current path. If the internal pressure of the battery increases further, the valve portion 26a breaks, forming a gas outlet.

[0021] The structure of the sealing body is not limited to the structure shown in Fig. 1. The sealing body may have a laminated structure including two valve bodies, or may have a convex sealing body cap that covers the valve body.

[0022] For example, multiple cylindrical batteries 10 are connected in series to form a module. In a battery module including the cylindrical batteries 10 of this embodiment, the external leads are connected to the open end 16b and the sealing body 17 by welding or the like. By connecting the external leads to the open end 16b, the connection distance between the batteries can be made shorter than when the external leads are connected to the bottom surface of the outer can 16.

[0023] The crimping and fixing structure of sealing body 17 by protrusion 16a of outer can 16 and opening edge 16b will be described below with reference to Fig. 2. Fig. 2 is an enlarged view of a portion of the upper end of the outer can in Fig. 1.

[0024] The outer can 16 has a protruding portion 16a that protrudes radially inward from its side surface. The protruding portion 16a compresses the gasket 18 radially inward to crimp and fix the sealing body 17. In this embodiment, the protruding portion 16a is formed around the entire circumference of the outer can 16. The protruding portion 16a is formed in an annular shape along the circumferential direction of the outer can 16 by spinning from the outside of the side surface.

[0025] 2, only one protrusion 16a is formed in the vertical direction, but multiple protrusions may be formed. The shape of the protrusion 16a is not particularly limited, and the cross section may be a substantially V-shape as shown in FIG. 2, a substantially U-shape, a substantially W-shape, or the like. One or multiple protrusions 16a may be formed at a portion of the circumferential direction of the outer can 16. In this case, from the viewpoint of improving the sealing performance of the inside of the battery, it is preferable that a pair of protrusions 16a are formed so as to face each other in the radial direction.

[0026] The opening edge 16b is formed by bending outward the opening edge (upper end) of the outer can 16, and extends radially outward approximately horizontally. The length L1 of the opening edge 16b is, for example, 0.5 to 3 mm. Here, the length L1 of the opening edge 16b means the length along the radial direction from the side surface to the end of the outer can 16. Like the grooved portion 23, the opening edge 16b is formed in an annular shape along the circumferential direction of the outer can 16.

[0027] In this embodiment, the open end 16b is formed around the entire circumference of the outer can 16. This allows external leads to be connected to the open end 16b in any direction in the circumferential direction of the outer can 16.

[0028] One or more open edges 16b may be formed at a portion in the circumferential direction of the outer can 16. This allows the outer dimensions of the battery in the radial direction to be reduced, thereby reducing the spacing between batteries and increasing the density of the battery module.

[0029] 3, the cylindrical battery 10 may further include a conductive member 30 joined to the open end 16b. This allows external leads to be connected to the surface of the conductive member 30, which has a larger area than the open end 16b, when the cylindrical battery 10 is modularized, and the conductive member 30 functions as an external terminal. This further improves the workability of connecting the external terminals formed on the open end 16b of the outer can 16 to the external leads. The conductive member 30 is, for example, a flat metal plate. The thickness of the conductive member 30 is, for example, 0.05 to 0.5 mm.

[0030] The position of the outer end 30a of the conductive member 30 is not particularly limited, and for example, as shown in Fig. 3, the outer end 30a may be substantially aligned with the open end of the outer can 16. The position of the inner end 30b of the conductive member 30 is not particularly limited, and for example, as shown in Fig. 3, it may be located outside the inner end of the gasket 18. Furthermore, the conductive member 30 may be a ring-shaped plate member. The outer shape of the conductive member 30 is, for example, an outer diameter of 20 to 30 mm and a hollow cutout of 15 to 20 mm.

[0031] The conductive member 30 and the opening end 16b can be joined by, for example, welding or adhesive. Welding methods include laser welding and resistance welding, with laser welding being preferred. Adhesion methods include methods using adhesives or solder. A conductive adhesive is preferred. The surface roughness of the conductive member 30 may be increased to improve weldability. The material of the conductive member 30 is preferably the same as the main component of the material of the outer can 16. This makes it easier to join the conductive member 30 and the opening end 16b by laser welding. For example, the material of the conductive member 30 and the opening end 16b may be a steel plate material. The surface of the steel plate material may also be plated with, for example, nickel.

[0032] 4, the cross-sectional shape of gasket 18 may be L-shaped. Base portion 18a extending in the radial direction of gasket 18 prevents the outer peripheral edge of sealing body 17 from contacting groove portion 23. Upstanding portion 18b extending in the vertical direction of gasket 18 prevents the outer peripheral edge of sealing body 17 from contacting outer can 16, and is compressed between protruding portion 16a of outer can 16 and sealing body 17 to crimp and fix sealing body 17. The outer shape of gasket 18 is not particularly limited as long as base portion 18a and upstanding portion 18b can perform their respective functions.

[0033] Next, an example of a manufacturing method for a cylindrical battery 10 will be described with reference to FIG. 1. First, a cylindrical, bottomed outer can 16 made of steel plate material is pressed with a 90° bent portion formed near the top end, and the top end is trimmed to form an open end 16b with a length of 0.5 to 3 mm on the radially outer side. Next, insulating plates 19 and 20 are placed above and below the electrode assembly 14, respectively, and the outer can 16 is housed. A negative electrode lead 22 is welded to the bottom of the outer can 16, and a groove 23 is formed in the side of the outer can 16 by pressing. Thereafter, a sealing member 17 is welded to the positive electrode lead 21, and an appropriate amount of nonaqueous electrolyte is poured into the interior of the outer can 16. After the liquid is poured in, the gasket 18 and sealing body 17 are placed in the upper part of the grooved portion 23, and the side surface of the outer can 16 is spun from the outside to form a ring-shaped protrusion 16a along the circumferential direction of the outer can 16. The sealing body 17 is then crimped and fixed radially inward by the protrusion 16a via the gasket 18, thereby producing a cylindrical battery.

[0034] As described above, in cylindrical battery 10, open end 16b of outer can 16 extends radially outward, and sealing body 17 is fixed by radial crimping using protrusion 16a. Cylindrical battery 10 ensures a sufficient connection area for the external lead at open end 16b, improving the stability and ease of connection between the outer can and the external lead when modularizing cylindrical battery 10. [Explanation of symbols]

[0035] 10 Cylindrical battery, 11 Positive electrode, 12 Negative electrode, 13 Separator, 14 Electrode body, 16 Outer can, 16a Protrusion, 16b Opening end, 17 Sealing body, 18 Gasket, 19, 20 Insulating plate, 21 Positive electrode lead, 22 Negative electrode lead, 23 Grooved portion, 25 Internal terminal plate, 25a Annular portion, 25b Center portion, 25c Vent, 26 Rupture plate, 26a Valve portion, 27 Insulating plate, 27a Opening, 27b Vent, 30 Conductive member, 30a Outer end, 30b Inner end

Claims

1. an electrode assembly including a positive electrode and a negative electrode; a cylindrical outer can with a bottom that houses the electrode assembly and is connected to either the positive electrode or the negative electrode; a sealing body connected to the other of the positive electrode and the negative electrode, the outer can has a protruding portion on a side surface protruding radially inward, and an opening end portion extending radially outward and positioned radially outward of the side surface, The sealing body is fixed by crimping radially inward by the protrusion via a gasket.

2. The cylindrical battery according to claim 1 , wherein the open end is formed around the entire circumference of the outer can.

3. An electrode body including a positive electrode and a negative electrode; a cylindrical outer can with a bottom that houses the electrode assembly and is connected to either the positive electrode or the negative electrode; a sealing body connected to the other of the positive electrode and the negative electrode, the outer can has a protruding portion on a side surface protruding radially inward, and an open end portion extending radially outward; The sealing body is fixed by crimping to the radially inner side by the protruding portion via a gasket, The cylindrical battery has one or more open ends formed at a portion of the circumferential direction of the outer can.

4. An electrode body including a positive electrode and a negative electrode; a cylindrical outer can with a bottom that houses the electrode assembly and is connected to either the positive electrode or the negative electrode; a sealing body connected to the other of the positive electrode and the negative electrode, the outer can has a protruding portion on a side surface protruding radially inward, and an open end portion extending radially outward; The sealing body is fixed by crimping to the radially inner side by the protruding portion via a gasket, The cylindrical battery further comprises a conductive member joined to the open end.

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