Cylindrical battery

Abstract

Provided is a cylindrical battery capable of avoiding functional loss of a sealing body when a lead plate is welded to a positive electrode external terminal and having an excellent gas discharging function.　The cylindrical battery (10) includes: an electrode body in which a positive electrode plate and a negative electrode plate are wound with a separator therebetween; an electrolyte; a bottomed cylindrical outer can that houses the electrode body and the electrolyte; and a sealing body (30) that closes an opening of the outer can, wherein the sealing body (30) includes a rupture plate (33) that is caulked and fixed to the opening of the outer can with a gasket (21) therebetween, and an external terminal (35) that is not caulked and fixed to the opening of the outer can, the rupture plate (33) has a valve part (33B) that is ruptured when an internal battery pressure rises, and the external terminal (35) is fixed to an upper surface portion of a valve part (33B).

Description

[Technical field]

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

[0002] Conventionally, cylindrical batteries having a sealing body that closes the opening of the outer can are known (for example, Patent Document 1). In the sealing body of the cylindrical battery, a rupture plate and a metal plate are laminated with an insulating plate interposed therebetween, and the rupture plate and the metal plate are welded together to form a current path inside the sealing body. In the sealing body, when the internal pressure of the battery rises in the event of an abnormality, the rupture plate deforms and breaks the metal plate to cut off the current path, and when the internal pressure rises further, the rupture plate breaks to form a gas exhaust port.

[0003] The cylindrical battery is used as a power source for electronic devices such as mobile phones, digital cameras, video cameras, and notebook computers. When the cylindrical battery is installed inside the electronic device, lead plates are joined to the positive and negative external terminals to connect the cylindrical batteries together. In recent years, various joining methods such as wire bonding, laser welding, and resistance welding have been used for this joining. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2016 / 157749 Summary of the Invention [Problem to be solved by the invention]

[0005] In the cylindrical battery, since the rupture plate serves as the positive external terminal, heat or impact may be applied to the joint between the rupture plate and the metal plate depending on the joining method. In this case, the metal plate may come off the rupture plate due to heat or impact during welding, leading to a loss of function of the sealing body. In addition, if a conventional terminal cap is applied to the cylindrical battery, the gas discharge ability may be hindered.

[0006] An object of the present disclosure is to provide a cylindrical battery that can avoid loss of function of a sealing body when a lead plate is welded to a positive electrode external terminal and has excellent gas discharge function. [Means for solving the problem]

[0007] A cylindrical battery according to one embodiment of the present disclosure is a cylindrical battery having an electrode assembly in which a positive electrode plate and a negative electrode plate are wound with a separator interposed therebetween, an electrolyte, a cylindrical outer can with a bottom that houses the electrode assembly and the electrolyte, and a sealing body that closes the opening of the outer can, wherein the sealing body includes a rupture plate that is crimped and fixed to the opening of the outer can via a gasket, and an external terminal that is not crimped and fixed to the opening of the outer can, the rupture plate has a valve portion that ruptures when the internal pressure of the battery increases, and the external terminal is fixed to the upper surface of the valve portion. Effect of the Invention

[0008] According to one aspect of the present disclosure, it is possible to provide a cylindrical battery that can avoid loss of function of a sealing body when a lead plate is welded to a positive electrode external terminal and has excellent gas discharge function. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a cross-sectional view of a cylindrical battery according to an embodiment. [Diagram 2] FIG. 2 is an enlarged view of a sealing body and its vicinity according to an embodiment of the present invention. [Diagram 3] FIG. 4 is an enlarged view of a sealing body and its vicinity of a cylindrical battery that is another example of an embodiment. [Figure 4] FIG. 4 is an enlarged view of a sealing body and its vicinity of a cylindrical battery that is another example of an embodiment. [Diagram 5] FIG. 4 is an enlarged view of a sealing body and its vicinity of a cylindrical battery that is another example of an embodiment. [Figure 6] FIG. 4 is an enlarged view of a sealing body and its vicinity of a cylindrical battery that is another example of an embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, an embodiment of the present disclosure will be described with reference to the drawings. The shapes, materials, and numbers described below are examples for the purpose of explanation and can be changed as appropriate according to the specifications of the cylindrical battery. In the following, the same reference numerals are used to denote equivalent elements in all drawings.

[0011] The cylindrical battery 10 will be described with reference to Fig. 1. Fig. 1 is a cross-sectional view of the cylindrical battery 10.

[0012] 1, a cylindrical battery 10 as an example of an embodiment includes an electrode assembly 14, an electrolyte, an exterior can 20 that contains the electrode assembly 14 and the electrolyte, and a sealing body 30 that closes the opening of the exterior can 20. The electrode assembly 14 includes a positive electrode plate 11, a negative electrode plate 12, and a separator 13, and has a structure in which the positive electrode plate 11 and the negative electrode plate 12 are spirally wound with the separator 13 interposed therebetween. In the following description, for ease of explanation, the sealing body 30 side of the cylindrical battery 10 (the opening side of the exterior can 20) is referred to as the top, and the bottom portion 20A side of the exterior can 20 is referred to as the bottom.

[0013] The positive electrode plate 11 has a positive electrode core and a positive electrode mixture layer formed on at least one surface of the core. For the positive electrode core, a foil of a metal stable in the potential range of the positive electrode plate 11, such as aluminum or an aluminum alloy, or a film with the metal disposed on the surface layer can be used. The positive electrode mixture layer contains a positive electrode active material, a conductive agent such as acetylene black, and a binder such as polyvinylidene fluoride, and is preferably formed on both sides of the positive electrode core. For the positive electrode active material, for example, a lithium transition metal composite oxide is used. The positive electrode plate 11 can be manufactured by applying a positive electrode mixture slurry containing a positive electrode active material, a conductive agent, and a binder, etc., onto the positive electrode core, drying the coating, and then compressing the coating to form a positive electrode mixture layer on both sides of the core.

[0014] The negative electrode plate 12 has a negative electrode core and a negative electrode mixture layer formed on at least one surface of the core. For the negative electrode core, a foil of a metal such as copper or a copper alloy that is stable in the potential range of the negative electrode plate 12, or a film with the metal disposed on the surface layer, can be used. The negative electrode mixture layer contains a negative electrode active material and a binder such as styrene-butadiene rubber (SBR), and is preferably formed on both sides of the negative electrode core. For the negative electrode active material, for example, graphite, a silicon-containing compound, etc. are used. The negative electrode plate 12 can be manufactured by applying a negative electrode mixture slurry containing a negative electrode active material, a binder, etc., onto the negative electrode core, drying the coating, and then rolling the coating to form a negative electrode mixture layer on both sides of the core.

[0015] For example, a non-aqueous electrolyte is used as the electrolyte. The non-aqueous electrolyte includes a non-aqueous solvent and an electrolyte salt dissolved in the non-aqueous solvent. For the non-aqueous solvent, esters, ethers, nitriles, amides, and a mixed solvent of two or more of these can be used. The non-aqueous solvent may contain a halogen-substituted product in which at least a part of the hydrogen of these solvents is substituted with a halogen atom such as fluorine. The non-aqueous electrolyte is not limited to a liquid electrolyte, and may be a solid electrolyte. For the electrolyte salt, a lithium salt such as LiPF6 is used. The type of electrolyte is not particularly limited, and may be an aqueous electrolyte.

[0016] The cylindrical battery 10 has insulating plates 15 and 16 arranged above and below the electrode body 14. In the example shown in FIG. 1, a positive electrode lead 17 connected to the positive electrode plate 11 extends through a through hole in the insulating plate 15 toward the sealing body 30, and a negative electrode lead 18 connected to the negative electrode plate 12 extends through the outside of the insulating plate 16 toward the bottom portion 20A of the outer can 20. The positive electrode lead 17 is connected to the lower surface of the metal plate 31, which is the bottom plate of the sealing body 30, by welding or the like, and the rupture plate 33 of the sealing body 30, which is electrically connected to the metal plate 31, serves as a positive electrode external terminal. The negative electrode lead 18 is connected to the inner surface of the bottom portion 20A of the outer can 20 by welding or the like, and the outer can 20 serves as a negative electrode external terminal.

[0017] As described above, the cylindrical battery 10 has an outer can 20 and a sealing body 30 that closes the opening of the outer can 20. The outer can 20 is a cylindrical metal container with a bottom including a bottom portion 20A and a side portion 20B. The bottom portion 20A is disk-shaped, and the side portion 20B is cylindrically formed along the outer peripheral edge of the bottom portion 20A. The sealing body 30 has a rupture plate 33 that is fixed to the opening of the outer can 20 by crimping via a gasket 21.

[0018] More specifically, the rupture plate 33 is supported by the grooved portion 20C of the outer can 20 and is fixed by crimping with a shoulder portion 20D of the outer can 20. The grooved portion 20C is formed in an annular shape along the circumferential direction of the outer can 20, with a part of the side portion 20B protruding inward near the opening of the outer can 20. The shoulder portion 20D is formed in an annular shape along the circumferential direction of the outer can 20 at the open end.

[0019] The sealing body 30 will be described in detail with reference to Figures 1 and 2. Figure 2 is an enlarged view of the sealing body 30 and its vicinity.

[0020] As described above, the sealing body 30 is a disk-shaped member that closes the opening of the exterior can 20, and functions as a current interruption mechanism and a safety valve. The sealing body 30 has a structure in which a metal plate 31, an insulating plate 32, a rupture plate 33, and an external terminal 35 are laminated in this order from the electrode body 14 side. The rupture plate 33 is formed with a valve portion 33B that breaks when the internal pressure of the battery increases.

[0021] The metal plate 31 includes an annular portion 31A to which the positive electrode lead 17 is connected, and a thin-walled central portion 31B that is cut off from the annular portion 31A when the internal pressure of the battery exceeds a predetermined threshold. The insulating plate 32 insulates the metal plate 31 except for the connection portion between the central portion 31B and the valve portion 33B. The insulating plate 32 has an opening 32A formed in the radial center.

[0022] The rupture plate 33 is disposed opposite the metal plate 31 with the insulating plate 32 sandwiched therebetween. The rupture plate 33 is formed in a circular shape in a plan view, and is produced, for example, by pressing a plate material of aluminum or an aluminum alloy. The rupture plate 33 has an outer periphery 33A that is supported by the grooved portion 20C of the outer can 20 and is fixed by crimping with a shoulder portion 20D of the outer can 20. A step portion 33S is formed on the upper surface portion of the outer periphery 33A, and a valve portion 33B is formed inside the outer periphery 33A.

[0023] The valve portion 33B functions as a safety valve that breaks when the battery internal pressure rises to release gas inside the battery. In a radial cross-sectional view, the valve portion 33B includes an inclined portion 33C that inclines downward from the outside to the inside, and a central portion 33D having a protrusion that protrudes toward the inside of the battery. The inclined portion 33C is interposed between the outer peripheral portion 33A and the central portion 33D, and the thickness of the inclined portion 33C is smaller than the thicknesses of the outer peripheral portion 33A and the central portion 33D. In addition, the thickness of the inclined portion 33C continuously decreases from the central portion 33D side to the outer peripheral portion 33A side. By forming the inclined portion 33C, it becomes easy to reverse and break the valve portion 33B when the battery internal pressure rises. The protrusion of the central portion 33D is connected to the central portion 31B of the metal plate 31 through the opening 32A of the insulating plate 32 by welding or the like.

[0024] In the cylindrical battery 10, the metal plate 31 to which the positive electrode lead 17 is connected is electrically connected to the rupture plate 33, forming a current path from the electrode body 14 to the rupture plate 33. In addition, in the cylindrical battery 10, when gas inside the battery rises as described above, the current interruption mechanism and safety valve are activated to ensure safety.

[0025] When the internal pressure of the cylindrical battery 10 increases, the metal plate 31 breaks, the central portion 31B is separated from the annular portion 31A, and the valve portion 33B is deformed so as to invert, thereby cutting off the current path. When the internal pressure of the battery increases further, the valve portion 33B breaks as described above, forming a gas exhaust port.

[0026] The external terminal 35 is a positive external terminal for connecting the cylindrical batteries 10 in series or parallel when, for example, the cylindrical batteries 10 are incorporated inside an electronic device. The external terminal 35 is provided on the upper surface of the rupture plate 33 inside the opening end of the outer can 20 (the portion corresponding to the inner peripheral end of the shoulder portion 20D). The external terminal 35 is also fixed to the upper surface of the valve portion 33B formed on the rupture plate 33. The external terminal 35 is not fixed to the opening of the outer can 20 by crimping. This makes it possible to prevent the gas exhaust port formed in the valve portion 33B from being blocked by the external terminal 35, and ensures excellent gas exhaust function of the cylindrical battery 10.

[0027] The external terminal 35 is made of metal, for example, a metal mainly composed of aluminum or iron. The external terminal 35 of this embodiment is produced by pressing a metal plate and is formed into a substantially disk-like shape. The external terminal 35 includes a disk-like main body 35A, a recess 35B formed in the substantially central portion of the main body 35A, and legs 35C formed on the outer periphery of the main body 35A.

[0028] The main body 35A is a portion to which the lead plate is welded. The main body 35A is formed in a flat disk shape. By forming the main body 35A flat, the welding area can be made as large as possible, and the welding work for welding the lead plate to the external terminal 35 can be made easier.

[0029] The vertical position of the main body 35A can be changed by changing the height of the recess 35B and the height of the leg 35C. This makes it possible to change the height of the main body 35A to correspond to, for example, the installation space for the cylindrical batteries 10 in the electronic device, or the position of the lead plates that join the cylindrical batteries 10 in the electronic device. The top end position of the main body 35A in this embodiment is preferably located above the top end position of the shoulder 20D of the exterior can 20. Note that if the lead plates are welded to the top end position of the shoulder 20D, the top end position of the main body 35A may be located on the same plane as the top end position of the shoulder 20D.

[0030] The main body 35A is disposed with a gap provided between it and the rupture plate 33. This makes it possible for the joint between the rupture plate 33 and the metal plate 31 to be less susceptible to vibration or heat caused by the joining when the lead plate is joined to the external terminal 35. For example, even when joining is performed by wire bonding or laser welding, which involves high-frequency vibration, loss of function of the sealing body 30, such as the metal plate 31 coming off the valve portion 33B, is avoided.

[0031] The recess 35B is formed in the approximate center of the main body 35A. In the external terminal 35 of this embodiment, the bottom surface of the recess 35B is joined to the valve portion 33B by laser welding. By adjusting the thickness of the bottom surface of the recess 35B, the laser load can be optimized.

[0032] The leg 35C is formed by bending downward the outer periphery or a part of the outer periphery of the external terminal 35. In this embodiment, the leg 35C is formed by bending diagonally downward, but may be formed by bending vertically downward. The leg 35C in this embodiment is formed in a convex shape at an arbitrary position on the outer periphery of the main body 35A in a plan view, but may be formed around half or the entire circumference of the main body 35A in a plan view.

[0033] The legs 35C can support the main body 35A relative to the rupture plate 33 by engaging with a step portion 33S formed on the outer periphery 33A of the rupture plate 33. This makes it possible to easily position the external terminal 35 when welding the external terminal 35 to the rupture plate 33.

[0034] As described above, cylindrical battery 10 can avoid loss of function of sealing body 30 when a lead plate is welded to the positive electrode side, and can ensure excellent gas discharge function.

[0035] An external terminal 35, which is another example of the embodiment, will be described in detail with reference to Fig. 3. Fig. 3 is an enlarged view of the sealing body 30 and its vicinity.

[0036] An external terminal 35 as another example of the embodiment includes a disk-shaped main body 35A, an annular recess 35B formed in the approximate center of the main body 35A, and legs 35C that support the main body 35A against the rupture plate 33. In the external terminal 35 of this embodiment, the above-mentioned lead plate is welded to the main body 35A surrounded by the annular recess 35B. Other than the above configuration, the external terminal 35 has the same configuration as the external terminal 35 shown in FIG.

[0037] According to the external terminal 35 of the present embodiment, by forming the recess 35B in an annular shape, the area of ​​the bottom surface of the recess 35B can be increased. This makes it possible to ensure a plurality of welding points when, for example, joining the bottom surface of the recess 35B and the valve portion 33B by spot welding.

[0038] An external terminal 35, which is another example of the embodiment, will be described in detail with reference to Fig. 4. Fig. 4 is an enlarged view of the sealing body 30 and its vicinity.

[0039] The external terminal 35, which is another example of the embodiment, includes a disk-shaped main body 35A having a predetermined thickness and a recess 35B formed in the approximate center of the main body 35A. The main body 35A has a predetermined thickness. The bottom surface of the main body 35A is formed to fit along the top surface of the rupture plate 33. The top surface of the main body 35A is formed flat.

[0040] According to the external terminal 35 of this embodiment, since the main body 35A has a predetermined thickness, even if a welding load such as a laser output needs to be increased when welding a lead plate to the external terminal 35, the welding load can be withstood. Furthermore, in joining the external terminal 35 and the valve portion 33B, the recess 35B, which is formed to be thinner than the thickness of the main body 35A, and the valve portion 33B are joined by laser welding, so that the load of laser welding can be reduced.

[0041] An external terminal 35, which is another example of the embodiment, will be described in detail with reference to Fig. 5. Fig. 5 is an enlarged view of the sealing body 30 and its vicinity.

[0042] An external terminal 35, which is another example of the embodiment, includes a disk-shaped main body 35A and an annular recess 35B formed in the approximate center of the main body 35A. In the external terminal 35, the above-mentioned lead plate is welded to the main body 35A surrounded by the annular recess 35B. Other than the above configuration, the external terminal 35 has the same configuration as the external terminal 35 shown in Fig. 4 and provides the same effects. Also, as with the external terminal 35 shown in Fig. 3, by forming the recess 35B in an annular shape, the area of ​​the bottom surface of the recess 35B used for welding to the valve portion 33B can be increased.

[0043] An external terminal 35, which is another example of the embodiment, will be described in detail with reference to Fig. 6. Fig. 6 is an enlarged view of the sealing body 30 and its vicinity.

[0044] The external terminal 35, which is another example of the embodiment, is formed only from a disk shape having a predetermined thickness. The external terminal 35 is joined to the upper surface of the central portion 33D of the valve portion 33B. The radial size of the external terminal 35 is smaller than the radial size of the central portion 33D of the valve portion 33B. According to the external terminal 35 of this embodiment, the external terminal 35 is formed only from a disk shape having a predetermined thickness, so that the processing cost can be reduced.

[0045] It should be noted that the present invention is not limited to the above-described embodiment and its modified examples, and various modifications and improvements are possible within the scope of the claims of this application. [Explanation of symbols]

[0046] 10 cylindrical battery, 11 positive electrode plate, 12 negative electrode plate, 13 separator, 14 electrode body, 15 insulating plate, 16 insulating plate, 17 positive electrode lead, 18 negative electrode lead, 20 outer can, 20A bottom surface, 20B side surface, 20C grooved portion, 20D shoulder portion, 21 gasket, 30 sealing body, 31 metal plate, 31A annular portion, 31B center portion, 32 insulating plate, 32A opening, 33 rupture plate, 33A outer periphery, 33B valve portion, 33C inclined portion, 33D center portion, 33S step portion, 35 external terminal, 35A main body, 35B recess, 35C leg portion

Claims

1. A cylindrical battery comprising: an electrode assembly in which a positive electrode plate and a negative electrode plate are wound with a separator interposed therebetween; an electrolyte; a cylindrical outer can with a bottom that contains the electrode assembly and the electrolyte; and a sealing body that closes an opening of the outer can, the sealing body includes a rupture plate that is crimped and fixed to the opening of the outer can via a gasket, and an external terminal that is not crimped and fixed to the opening of the outer can, The rupture plate has a valve portion that breaks when the internal pressure of the battery increases, The external terminal is fixed to an upper surface of the valve portion. Cylindrical battery.

2. 2. The cylindrical battery according to claim 1, The external terminal has a recess in an approximately central portion, the recess being recessed in an upper surface portion. the external terminal and the valve portion are welded to each other in the recess; Cylindrical battery.

3. 3. The cylindrical battery according to claim 2, The external terminal includes a main body formed in a plate shape and arranged with a gap between the main body and the rupture plate, and a leg portion supporting the main body against the rupture plate. Cylindrical battery.

4. 3. The cylindrical battery according to claim 2, The upper surface of the rupture plate is formed so as to be inclined toward the center in the radial direction, The bottom surface of the external terminal facing the upper surface of the rupture plate is formed along the shape of the upper surface of the rupture plate. Cylindrical battery.

5. A cylindrical battery according to any one of claims 2 to 4, The recess is formed in a ring shape in a plan view. Cylindrical battery.

6. 6. A cylindrical battery according to claim 1, The external terminals are formed of a metal containing aluminum or iron as a main component. Cylindrical battery.

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