Cylindrical battery

Abstract

Provided is 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. The cylindrical battery (10) comprises: an electrode body formed by winding a positive electrode plate and a negative electrode plate with a separator interposed therebetween; an electrolyte; a bottomed cylindrical outer can that accommodates the electrode body and the electrolyte; and a sealing body (30) that seals the opening of the outer can, the sealing body (30) comprising: a bursting plate (33) that is fixed to the opening of the outer can by caulking through a gasket (21); and an external terminal (35) that is not fixed to the opening of the outer can by caulking, the bursting plate (33) having a valve portion (33B) that ruptures when the internal pressure of the battery rises, and the external terminal (35) is fixed to the upper surface of the valve portion (33B).

Description

Technical Field

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

[0002] In the past, a cylindrical battery having a sealing body that blocks the opening of the outer can is known (for example, Patent Document 1). In the sealing body of the cylindrical battery, a bursting plate and a metal plate are stacked with an insulating plate therebetween, and the bursting plate and the metal plate are welded and joined to form a current path inside the sealing body. In the sealing body, if the internal pressure of the battery rises in an abnormal situation, the bursting plate is deformed, the metal plate ruptures, and the current path is cut off. If the internal pressure rises further, the bursting plate ruptures, thereby forming a gas discharge port.

[0003] However, the cylindrical battery is used as a power source for electronic devices such as mobile phones, digital cameras, video cameras, or notebook personal computers. When the cylindrical battery is assembled inside the electronic device, in order to connect the cylindrical batteries to each other, the lead plate is joined to the positive electrode external terminal and the negative electrode external terminal. In recent years, various joining methods such as wire bonding, laser welding, and resistance welding are used for this joining.

[0004] Prior Art Literature

[0005] Patent Literature

[0006] Patent Document 1: International Publication No. 2016 / 157749 Summary of the invention

[0007] -Problems to be solved by the invention-

[0008] In the above cylindrical battery, the burst plate becomes the positive electrode external terminal, so sometimes heat or impact is applied to the joint between the burst plate and the metal plate due to the joining method. In this case, the metal plate falls off from the burst plate due to the heat or impact during welding, which may cause functional loss of the sealing body. In addition, when the existing terminal cover is applied to the above cylindrical battery, the gas discharge capability may be hindered.

[0009] 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 an excellent gas discharge function.

[0010] -Methods for solving problems-

[0011] A cylindrical battery as one mode of the present invention comprises: an electrode body formed by winding a positive electrode plate and a negative electrode plate with a separator in between; an electrolyte; a bottomed cylindrical outer can that accommodates the electrode body and the electrolyte; and a sealing body that seals the opening of the outer can, wherein the sealing body includes: a bursting plate that is fixed to the opening of the outer can by caulking through a gasket; and an external terminal that is not fixed to the opening of the outer can by caulking, the bursting plate having a valve portion that ruptures when the internal pressure of the battery rises, and the external terminal is fixed to the upper surface of the valve portion.

[0012] -Effects of the Invention-

[0013] According to one aspect of the present disclosure, it is possible to provide a cylindrical battery that can avoid loss of function of the sealing body when welding the lead plate to the positive electrode external terminal and has an excellent gas discharge function. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a cross-sectional view of a cylindrical battery as an example of an embodiment.

[0015] Figure 2 This is an enlarged view of a sealing body and its vicinity as an example of an embodiment.

[0016] Figure 3 This is an enlarged view of a sealing body and its vicinity of a cylindrical battery as another example of the embodiment.

[0017] Figure 4 This is an enlarged view of a sealing body and its vicinity of a cylindrical battery as another example of the embodiment.

[0018] Figure 5 This is an enlarged view of a sealing body and its vicinity of a cylindrical battery as another example of the embodiment.

[0019] Figure 6 This is an enlarged view of a sealing body and its vicinity of a cylindrical battery as another example of the embodiment. DETAILED DESCRIPTION

[0020] The following drawings are used to illustrate the embodiments of the present disclosure. The shapes, materials, and numbers described below are examples for illustration and can be appropriately changed according to the specifications of the cylindrical battery. In the following drawings, the same reference numerals are given to the same elements and described.

[0021] use Figure 1 The cylindrical battery 10 will be described. Figure 1 is a cross-sectional view of the cylindrical battery 10 .

[0022] like Figure 1As shown in the figure, a cylindrical battery 10 as an example of an embodiment includes an electrode body 14, an electrolyte, an outer can 20 for storing the electrode body 14 and the electrolyte, and a sealing body 30 for sealing the opening of the outer can 20. The electrode body 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 wound in a spiral shape with the separator 13 interposed therebetween. In addition, for the sake of convenience in the following description, the sealing body 30 side (the opening side of the outer can 20) of the cylindrical battery 10 is set as the upper side, and the bottom surface 20A side of the outer can 20 is set as the lower side.

[0023] The positive electrode plate 11 has a positive electrode core and a positive electrode mixture layer formed on at least one side of the core. The positive electrode core can be made of a foil of a metal such as aluminum or aluminum alloy that is stable within the potential range of the positive electrode plate 11, or a film that configures the metal on the surface. 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 is, for example, a lithium transition metal composite oxide. The positive electrode plate 11 can be manufactured by the following steps: applying a positive electrode mixture slurry containing a positive electrode active material, a conductive agent, and a binder on the positive electrode core, drying the coating, and then compressing the coating to form the positive electrode mixture layer on both sides of the core.

[0024] The negative electrode plate 12 has a negative electrode core and a negative electrode mixture layer formed on at least one side of the core. The negative electrode core can be made of a foil of a metal such as copper or copper alloy that is stable within the potential range of the negative electrode plate 12, or a film that configures the metal on the surface. 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 may be, for example, graphite or a silicon-containing compound. The negative electrode plate 12 can be manufactured by the following steps: applying a negative electrode mixture slurry containing a negative electrode active material, a binder, etc. on the negative electrode core, drying the coating, and then pressing the coating to form negative electrode mixture layers on both sides of the core.

[0025] The electrolyte uses, for example, a non-aqueous electrolyte. The non-aqueous electrolyte includes a non-aqueous solvent and an electrolyte salt dissolved in the non-aqueous solvent. The non-aqueous solvent can use esters, ethers, nitriles, amides, and mixed solvents of two or more of these solvents. The non-aqueous solvent may also contain a halogen substitute in which at least a portion of the hydrogen of these solvents is replaced with a halogen atom such as fluorine. In addition, the non-aqueous electrolyte is not limited to a liquid electrolyte, and may also be a solid electrolyte. The electrolyte salt uses, for example, a lithium salt such as LiPF6. The type of electrolyte is not particularly limited, and may also be an aqueous electrolyte.

[0026] The cylindrical battery 10 has insulating plates 15 and 16 disposed above and below the electrode body 14, respectively. Figure 1In the example shown, the positive electrode lead 17 connected to the positive electrode plate 11 extends to the sealing body 30 side through the through hole of the insulating plate 15, and the negative electrode lead 18 connected to the negative electrode plate 12 extends to the bottom portion 20A side of the outer can 20 through the outer side of the insulating plate 16. The positive electrode lead 17 is connected to the lower surface of the metal plate 31 as the bottom plate of the sealing body 30 by welding or the like, and the burst plate 33 of the sealing body 30 electrically connected to the metal plate 31 becomes the 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 becomes the negative electrode external terminal.

[0027] As described above, the cylindrical battery 10 includes an outer can 20 and a sealing body 30 that seals the opening of the outer can 20. The outer can 20 is a metal container having a bottom cylindrical shape and including a bottom portion 20A and a side portion 20B. The bottom portion 20A is in the shape of a disk, and the side portion 20B is formed in a cylindrical shape along the outer peripheral edge of the bottom portion 20A. The sealing body 30 includes a bursting plate 33 that is fixed to the opening of the outer can 20 by caulking through a gasket 21.

[0028] In more detail, the bursting plate 33 is supported by the groove portion 20C of the outer can 20 and is fixed by caulking the shoulder portion 20D of the outer can 20. The groove portion 20C is formed in a ring shape along the circumferential direction of the outer can 20, with a part of the side portion 20B extending inward near the opening of the outer can 20. The shoulder portion 20D is formed in a ring shape along the circumferential direction of the outer can 20 at the opening end.

[0029] use Figure 1 as well as Figure 2 , the sealing body 30 will be described in detail. Figure 2 This is an enlarged view of the sealing body 30 and its vicinity.

[0030] As described above, the sealing body 30 is a disc-shaped member that seals the opening of the outer can 20 and has the function of 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 bursting plate 33, and an external terminal 35 are stacked in order from the electrode body 14 side. The bursting plate 33 is formed with a valve portion 33B that ruptures when the internal pressure of the battery rises.

[0031] The metal plate 31 is a metal plate including an annular portion 31A connected to the positive lead 17 and a thin central portion 31B that is cut away from the annular portion 31A when the internal pressure of the battery exceeds a predetermined threshold. The insulating plate 32 is a plate that insulates the portion other than the connection portion between the central portion 31B and the valve portion 33B of the metal plate 31. An opening 32A is formed in the radial center of the insulating plate 32.

[0032] The bursting plate 33 is disposed opposite to the metal plate 31 with the insulating plate 32 interposed therebetween. The bursting plate 33 is formed into a circular shape in a plan view, and is made, for example, by stamping a plate of aluminum or an aluminum alloy. The bursting plate 33 is supported by the groove portion 20C of the outer can 20, and has an outer peripheral portion 33A fixed by caulking by the shoulder portion 20D of the outer can 20. A step portion 33S is formed on the upper surface portion of the outer peripheral portion 33A, and a valve portion 33B is formed inside the outer peripheral portion 33A.

[0033] The valve portion 33B functions as a safety valve that ruptures when the internal pressure of the battery rises and discharges the gas inside the battery. The valve portion 33B includes an inclined portion 33C that tilts downward from the outside toward the inside in a radial cross-section and a central portion 33D having a protrusion protruding toward the inside of the battery. The inclined portion 33C is sandwiched between the outer peripheral portion 33A and the central portion 33D, and the thickness of the inclined portion 33C is smaller than the thickness of the outer peripheral portion 33A and the central portion 33D. In addition, the thickness of the inclined portion 33C decreases continuously from the central portion 33D side toward the outer peripheral portion 33A side. By forming the inclined portion 33C, the valve portion 33B is easily turned over and ruptured when the internal pressure of the battery 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.

[0034] In the cylindrical battery 10, the metal plate 31 connected to the positive electrode lead 17 and the bursting plate 33 are electrically connected to form a current path from the electrode body 14 to the bursting plate 33. In addition, as described above, in the cylindrical battery 10, when the gas inside the battery rises, the current interruption mechanism and the safety valve are operated to ensure safety.

[0035] When the internal pressure of the cylindrical battery 10 rises, the metal plate 31 is deformed, the central portion 31B is separated from the annular portion 31A, and the valve portion 33B is turned over. As a result, the current path is cut off. If the internal pressure of the battery further rises, the valve portion 33B is ruptured as described above to form a gas discharge port.

[0036] The external terminal 35 is, for example, a positive electrode external terminal for connecting the cylindrical batteries 10 in series or in parallel with each other when the cylindrical batteries 10 are assembled inside an electronic device. The external terminal 35 is provided on the upper surface of the burst plate 33 inside the opening end of the outer can 20 (the portion corresponding to the inner peripheral end of the shoulder 20D). In addition, the external terminal 35 is fixed to the upper surface of the valve portion 33B formed in the burst plate 33. In addition, the external terminal 35 is not fixed to the opening of the outer can 20 by caulking. Thus, it is possible to prevent the gas discharge port formed in the valve portion 33B from being blocked by the external terminal 35, and it is possible to ensure the excellent gas discharge function of the cylindrical battery 10.

[0037] 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 made by stamping a metal plate and is formed into a roughly disc shape. The external terminal 35 includes: a disc-shaped body 35A; a recess 35B formed in the approximate center of the body 35A; and a foot 35C formed on the outer periphery of the body 35A.

[0038] 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. The main body 35A is formed flatly, thereby making it possible to expand the welding area as much as possible, and facilitating the welding operation when welding the lead plate to the external terminal 35.

[0039] The position of the main body 35A in the vertical direction can be changed by changing the height of the recess 35B and the height of the leg 35C. Thus, for example, the height of the main body 35A can be changed corresponding to the assembly space of the cylindrical battery 10 in the electronic device or the position of the lead plate to which the cylindrical battery 10 is connected in the electronic device. The upper end position of the main body 35A in this embodiment is preferably a position higher than the upper end position of the shoulder 20D of the outer can 20. In addition, when the lead plate is welded to the upper end position of the shoulder 20D, the upper end position of the main body 35A and the upper end position of the shoulder 20D can also be arranged on the same plane.

[0040] The main body 35A is configured to provide a gap between the main body 35A and the burst plate 33. Thus, when the lead plate is joined to the external terminal 35, the joint between the burst plate 33 and the metal plate 31 is not easily affected by vibration or heat caused by the joining. For example, even when joining is performed by wire bonding or laser welding accompanied by high-frequency vibration, it is possible to avoid loss of function of the sealing body 30 such as the metal plate 31 falling off from the valve portion 33B.

[0041] A recess 35B is formed substantially in the center of the main body 35A. In the external terminal 35 of this embodiment, the bottom of the recess 35B is joined to the valve portion 33B by laser welding. The load of the laser can be optimized by adjusting the thickness of the bottom of the recess 35B.

[0042] The foot portion 35C is formed by bending the outer peripheral edge portion or a part of the outer peripheral edge portion of the external terminal 35 downward. In the present embodiment, the foot portion 35C is formed by bending obliquely downward, but it can also be formed by bending vertically downward. The foot portion 35C of the present embodiment is formed in a convex shape at any position of the outer peripheral edge of the main body 35A when viewed from above, but it can also be a structure formed on half or the entire circumference of the main body 35A when viewed from above.

[0043] The leg portion 35C engages with the stepped portion 33S formed on the outer peripheral portion 33A of the bursting plate 33, thereby supporting the main body 35A with respect to the bursting plate 33. Thus, when the external terminal 35 is welded to the bursting plate 33, the external terminal 35 can be easily positioned.

[0044] As described above, according to the cylindrical battery 10 , it is possible to avoid loss of function of the sealing body 30 when the lead plate is welded to the positive electrode side, and to ensure an excellent gas discharge function.

[0045] use Figure 3 , the external terminal 35 as another example of the embodiment will be described in detail. Figure 3 This is an enlarged view of the sealing body 30 and its vicinity.

[0046] The external terminal 35 as another embodiment includes: a disk-shaped main body 35A; an annular recess 35B formed in the substantially central portion of the main body 35A; and a leg 35C for supporting the main body 35A with respect to the burst plate 33. In the external terminal 35 of this embodiment, the lead plate is welded to the main body 35A surrounded by the annular recess 35B. Figure 2 The external terminals 35 shown have the same structure.

[0047] According to the external terminal 35 of this embodiment, the recess 35B is formed into a ring shape, so that the area of ​​the bottom of the recess 35B can be increased. Thus, when the bottom of the recess 35B and the valve portion 33B are joined by spot welding, for example, multiple welding locations can be ensured.

[0048] use Figure 4 , the external terminal 35 as another example of the embodiment will be described in detail. Figure 4 This is an enlarged view of the sealing body 30 and its vicinity.

[0049] The external terminal 35 as another embodiment includes: a disc-shaped body 35A having a given thickness; and a recessed portion 35B formed in a substantially central portion of the body 35A. The body 35A has a given thickness. The bottom portion of the body 35A is formed along the upper surface portion of the blasting plate 33. The upper surface portion of the body 35A is formed flat.

[0050] According to the external terminal 35 of the present embodiment, the main body 35A has a given thickness, so that when the lead plate is welded to the external terminal 35, even if a welding load such as a laser output needs to be increased, the welding load can be withstood. In addition, in the joining of the external terminal 35 and the valve portion 33B, the recessed portion 35B formed thinner than the thickness of the main body 35A and the valve portion 33B are joined by laser welding, thereby reducing the load of laser welding.

[0051] use Figure 5 , the external terminal 35 as another example of the embodiment will be described in detail. Figure 5 This is an enlarged view of the sealing body 30 and its vicinity.

[0052] The external terminal 35 as another embodiment includes a disk-shaped main body 35A and an annular recess 35B formed in the substantially central portion of the main body 35A. In the external terminal 35, the lead plate is welded to the main body 35A surrounded by the annular recess 35B. Figure 4 The same structure as the external terminal 35 shown in FIG. Figure 3 Similarly to the external terminal 35 shown, by forming the recessed portion 35B in a ring shape, the area of ​​the bottom surface portion of the recessed portion 35B used for welding with the valve portion 33B can be increased.

[0053] use Figure 6 , the external terminal 35 as another example of the embodiment will be described in detail. Figure 6 This is an enlarged view of the sealing body 30 and its vicinity.

[0054] The external terminal 35 as another example of the embodiment is formed only by a disc shape having a given thickness. The external terminal 35 is bonded 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, by setting the external terminal 35 only to a disc shape having a given thickness, it is possible to reduce processing costs.

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

[0056] -Explanation of symbols-

[0057] 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 portion, 20B side portion, 20C groove portion, 20D shoulder portion, 21 gasket, 30 sealing body, 31 metal plate, 31A annular portion, 31B central portion, 32 insulating plate, 32A opening portion, 33 bursting plate, 33A outer peripheral portion, 33B valve portion, 33C inclined portion, 33D central portion, 33S height difference portion, 35 external terminal, 35A main body, 35B recessed portion, 35C foot portion.

Claims

1. A cylindrical battery comprising: an electrode body formed by winding a positive electrode plate and a negative electrode plate with a separator interposed therebetween; an electrolyte; a bottomed cylindrical outer can for accommodating the electrode body and the electrolyte; and a sealing body for sealing an opening of the outer can, The sealing body includes: a bursting plate fixed to the opening of the outer can by caulking through a gasket; and an external terminal not fixed to the opening of the outer can by caulking, The bursting plate has a valve portion that ruptures when the internal pressure of the battery rises. The external terminal is fixed to the upper surface of the valve portion. The external terminal has a recessed portion in the substantially central portion thereof. The external terminal and the valve portion are welded in the recessed portion.

2. The cylindrical battery according to claim 1, in, The external terminal includes: a main body formed in a plate shape and arranged to provide a gap between the main body and the bursting plate; and a leg portion supporting the main body with respect to the bursting plate.

3. The cylindrical battery according to claim 1, in, The upper surface of the bursting plate is formed to be inclined toward the central portion in the radial direction. A bottom surface portion of the external terminal facing the upper surface portion of the bursting plate is formed along the shape of the upper surface portion of the bursting plate.

4. The cylindrical battery according to any one of claims 1 to 3, in, The recessed portion is formed in a ring shape in a plan view.

5. The cylindrical battery according to any one of claims 1 to 3, in, The external terminal is formed of a metal mainly composed of aluminum or iron.

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