Cylindrical battery

Abstract

The objective of the present invention is to provide a cylindrical battery with which it is possible to suppress deformation of a sealing plate when the sealing plate is being crimped. A cylindrical battery according to an embodiment of the present disclosure includes an electrode body in which a positive electrode plate and a negative electrode plate are wound with a separator interposed therebetween, an electrolyte, a bottomed cylindrical outer can (20) accommodating the electrode body and the electrolyte, and a sealing plate (30) blocking an opening portion of the outer can (20), wherein: the sealing plate (30) includes a flange portion (31) which is secured by crimping to the opening portion of the outer can (20), a terminal portion (32) formed on the radially inner side of the flange portion (31), and a thin-walled portion (33) which is formed on the radially outer side of the sealing plate (30), and which connects the flange portion (31) and the terminal portion (32); and the thin-walled portion (33) is formed in such a way as to be inclined upward toward the outside from the radially inner side of the sealing plate (30), and is formed in such a way as to connect a part below the central portion of an outer circumferential surface (32A) of the terminal portion (32) to a part above the central portion of an inner circumferential surface (31A) of the flange portion (31).

Description

Technical Field

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

Background Art

[0002] A cylindrical battery has a bottomed cylindrical outer can that houses an electrode body and an electrolyte, and a sealing body that closes the opening of the outer can (for example, Patent Document 1). The sealing body of the cylindrical battery is configured by laminating an external terminal plate and an internal terminal plate with an insulating plate interposed therebetween.

[0003] Some of the sealing bodies are composed only of a plate-like member (hereinafter referred to as a sealing plate). Since such a sealing plate can reduce the number of parts compared to the sealing body of the cylindrical battery, the manufacturing cost can be reduced. In addition, since the thickness can be made smaller than that of the sealing body of the cylindrical battery, the internal volume of the outer can can be increased, and a battery with a high energy density can be realized.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] By the way, a thin portion that breaks when an abnormality occurs in the battery and the internal pressure rises is formed in the sealing plate. However, when the sealing plate is caulked and fixed to the opening of the outer can, this thin portion may deform and the upper surface position of the sealing plate may fluctuate. As a result, the overall height of the cylindrical battery including the sealing plate may vary.

[0006] An object of the present disclosure is to provide a cylindrical battery capable of suppressing deformation of the sealing plate during caulking.

Means for Solving the Problems

[0007] A cylindrical battery according to one aspect of the present disclosure includes an electrode body in which a positive electrode plate and a negative electrode plate are wound with a separator interposed therebetween, an electrolyte, a bottomed cylindrical outer can that houses the electrode body and the electrolyte, and a sealing plate that closes an opening of the outer can. The sealing plate has a flange portion caulked and fixed to the opening of the outer can, a terminal portion formed radially inward of the flange portion, and a thin portion connecting the flange portion and the terminal portion. The thin portion is formed to incline upward from the radially inner side to the outer side of the sealing plate, and is formed to connect downward from the central portion of the outer peripheral surface of the terminal portion and upward from the central portion of the inner peripheral surface of the flange portion.

Effects of the Invention

[0008] According to one aspect of the present disclosure, deformation of the sealing plate can be suppressed during caulking of the sealing plate.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Modes for Carrying Out the Invention

[0010] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. The shapes, materials, and numbers described below are examples and can be appropriately changed according to the specifications of the cylindrical battery. In the following, the same reference numerals will be given to equivalent elements in all the drawings for description.

[0011] With reference to FIG. 1, a cylindrical battery 10 as an example of an embodiment will be described. FIG. 1 is a cross-sectional view of the cylindrical battery 10.

[0012] As shown in FIG. 1, the cylindrical battery 10 includes an electrode body 14, an electrolyte, an outer can 20 that houses the electrode body 14 and the electrolyte, and a sealing plate 30 that closes 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. Further, hereinafter, for convenience of explanation, the side of the sealing plate 30 of the cylindrical battery 10 (the opening side of the outer can 20) is defined as the upper side, and the side of the bottom surface portion 20A of the outer can 20 is defined as the lower side.

[0013] The positive electrode plate 11 has a positive electrode core body and a positive electrode mixture layer formed on at least one surface of the core body. As the positive electrode core body, a foil of a metal stable within the potential range of the positive electrode plate 11, such as aluminum or an aluminum alloy, or a film having such a metal disposed on the surface layer can be used. The positive electrode mixture layer includes 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 surfaces of the positive electrode core body. As 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 onto the positive electrode core body, drying the coating film, and then compressing the coating film to form the positive electrode mixture layer on both surfaces of the core body.

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

[0015] For the electrolyte, for example, 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. As the non-aqueous solvent, esters, ethers, nitriles, amides, and mixed solvents 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. Note that the non-aqueous electrolyte is not limited to a liquid electrolyte and may be a solid electrolyte. As the electrolyte salt, for example, a lithium salt such as LiPF6 is used. The type of the electrolyte is not particularly limited and may be an aqueous electrolyte.

[0016] The cylindrical battery 10 has insulating plates 15 and 16 respectively arranged above and below the electrode body 14. In the example shown in FIG. 1, the positive electrode lead 17 connected to the positive electrode plate 11 extends toward the sealing plate 30 through the through hole of the insulating plate 15, and the negative electrode lead 18 connected to the negative electrode plate 12 extends toward the bottom surface portion 20A side of the outer can 20 through the outside of the insulating plate 16. The positive electrode lead 17 is connected to the bottom surface of the terminal portion 32 of the sealing plate 30 by welding or the like, and the sealing plate 30 serves as the positive electrode external terminal. The negative electrode lead 18 is connected to the inner surface of the bottom surface portion 20A of the outer can 20 by welding or the like, and the outer can 20 serves as the negative electrode external terminal.

[0017] As described above, the cylindrical battery 10 has an outer can 20 and a sealing plate 30 that closes the opening of the outer can 20. The outer can 20 is a bottomed cylindrical metal container including a bottom surface portion 20A and a side surface portion 20B. The bottom surface portion 20A has a disc shape, and the side surface portion 20B is formed in a cylindrical shape along the outer peripheral edge of the bottom surface portion 20A. The sealing plate 30 is caulked and fixed to the opening of the outer can 20 via a gasket 21.

[0018] More specifically, the sealing plate 30 is supported by the groove portion 20C of the outer can 20 and caulked and fixed by the caulking portion 20D of the outer can 20. The groove portion 20C is formed in an annular shape along the circumferential direction of the outer can 20 with a part of the side surface portion 20B projecting inward in the vicinity of the opening of the outer can 20. The caulking portion 20D is formed in an annular shape along the circumferential direction of the outer can 20 at the opening end portion.

[0019] The sealing plate 30 will be described with reference to FIG. 2. FIG. 2 is a cross-sectional view of the sealing plate 30.

[0020] As described above, the sealing plate 30 is a member that closes the opening of the outer can 20. The sealing plate 30 is formed in a substantially disc shape in plan view and is manufactured, for example, by pressing a plate material of aluminum or an aluminum alloy. The sealing plate 30 has a function of exhausting the gas inside the cylindrical battery 10 when the internal pressure of the cylindrical battery 10 rises during an abnormality of the cylindrical battery 10.

[0021] As shown in FIG. 2, the sealing plate 30 includes a flange portion 31 caulked and fixed to the opening of the outer can 20, a terminal portion 32 formed radially inward of the flange portion 31, and a thin portion 33 connecting the flange portion 31 and the terminal portion 32.

[0022] The flange portion 31 is a portion supported by the grooved portion 20C of the outer can 20 and caulked and fixed by the caulked portion 20D of the outer can 20. The flange portion 31 is formed in a substantially annular shape. The outer end portion 33B of the thin portion 33 is connected to the inner peripheral surface 31A of the flange portion 31. Hereinafter, when the inner peripheral surface 31A of the flange portion 31 is equally divided into three parts in the vertical direction, each part will be referred to as an upper portion, a central portion, and a lower portion. The upper portion of the inner peripheral surface 31A includes at least the upper end of the inner peripheral surface 31A.

[0023] The terminal portion 32 is a portion to which the positive electrode lead 17 is joined and serves as a positive electrode internal terminal. In order to connect the cylindrical batteries 10 to each other when a plurality of cylindrical batteries 10 are configured as a battery pack, a lead plate can be joined to either the upper surface of the terminal portion 32 or the flange portion 31. The terminal portion 32 is formed in a substantially disc shape. The inner end portion 33A of the thin portion 33 is connected to the outer peripheral surface 32A of the terminal portion 32. Hereinafter, when the outer peripheral surface 32A of the terminal portion 32 is equally divided into three parts in the vertical direction, each part will be referred to as an upper portion, a central portion, and a lower portion. The lower portion of the outer peripheral surface 32A includes at least the lower end of the outer peripheral surface 32A.

[0024] The thin-walled portion 33 is a portion that breaks when the internal pressure of the cylindrical battery 10 rises. Also, the thin-walled portion 33 is a portion that connects the terminal portion 32 and the flange portion 31 as described above. The thin-walled portion 33 is formed in a substantially annular shape.

[0025] The thin-walled portion 33 is formed so as to incline upward from the inner side to the outer side in the radial direction of the sealing plate 30. For example, both the upper surface and the bottom surface of the thin-walled portion 33 are formed so as to incline upward from the inner side to the outer side in the radial direction. Also, it is preferable that the inclination angle of the upper surface of the thin-walled portion 33 is formed to be smaller than the inclination angle of the bottom surface of the thin-walled portion 33.

[0026] The thin-walled portion is formed to be tapered from the inner side to the outer side in the radial direction of the sealing plate. For example, in the thin-walled portion 33, the thickness (length in the vertical direction) of the outer end portion 33B is formed to be smaller than that of the inner end portion 33A. Also, in the thin-walled portion 33, it is preferable that the thickness of the outer end portion 33B is formed to be the minimum.

[0027] When the internal pressure of the cylindrical battery 10 rises, the sealing plate 30 is pressed upward by the gas pressure, and the thin-walled portion 33 reverses from a state of inclining upward from the inner side to the outer side in the radial direction to a state of inclining downward, and the outer end portion 33B of the thin-walled portion 33 breaks to form a gas discharge port.

[0028] In the thin-walled portion 33, the inner end portion 33A is connected to the lower part (central part and lower part) from the central part of the outer peripheral surface 32A of the terminal portion 32, and the outer end portion 33B is connected to the upper part (central part and upper part) from the central part of the inner peripheral surface 31A of the flange portion 31. Here, being connected to the lower part from the central part of the outer peripheral surface 32A means being connected to at least a part of the lower part from the central part of the outer peripheral surface 32A, and being connected to the upper part from the central part of the inner peripheral surface 31A means being connected to at least a part of the upper part from the central part of the inner peripheral surface 31A.

[0029] More preferably, in the thin-walled portion 33, the inner end portion 33A is connected to the lower portion of the outer peripheral surface 32A of the terminal portion 32, and the lower surface of the thin-walled portion 33 is formed to be continuous with the lower surface of the terminal portion 32. Further, in the thin-walled portion 33, the outer end portion 33B is connected to the upper portion of the inner peripheral surface 31A of the flange portion 31, and the upper surface of the thin-walled portion 33 is formed to be continuous with the upper surface of the flange portion 31.

[0030] According to the cylindrical battery 10, deformation of the sealing plate 30 can be suppressed during caulking of the sealing plate 30. More specifically, since the amount of deformation of the thin-walled portion 33 can be suppressed during caulking of the sealing plate 30, fluctuation in the vertical position of the terminal portion 32 can be suppressed.

[0031] Note that the present invention is not limited to the above-described embodiments and their modifications, and it goes without saying that various changes and improvements can be made within the scope of the matters described in the claims of the present application.

[0032] Hereinafter, the present disclosure will be further described by way of examples, but the present disclosure is not limited to these examples.

Example

[0033] <Example 1> [Fabrication of Sealing Plate] A sealing plate was fabricated by pressing an aluminum plate. In the sealing plate, a substantially annular flange portion that is caulked and fixed to the opening of the outer can was formed, a substantially disk-shaped terminal portion was formed radially inward of the flange portion, and a thin-walled portion that connects the terminal portion and the flange portion was formed. The thin-walled portion was formed to incline upward from the inner side to the outer side in the radial direction of the sealing plate. The thin-walled portion was formed to connect the lower portion of the outer peripheral surface of the terminal portion and the upper portion of the inner peripheral surface of the flange portion.

[0034] [Fabrication of Battery Case] A bottomed cylindrical outer can made of a steel plate and nickel-plated was plastically processed to form a circumferential grooved portion. The opening of the outer can was caulked and sealed using a sealing plate into which a gasket was inserted to produce an empty battery case having no electrode body and electrolyte.

[0035] <Example 2> A battery case was produced in the same manner as in Example 1, except that the thin-walled portion of the sealing plate was formed so as to connect the lower portion of the outer peripheral surface of the terminal portion and the central portion of the inner peripheral surface of the flange portion.

[0036] <Comparative Example 1> A battery case was produced in the same manner as in Example 1, except that the thin-walled portion of the sealing plate was formed so as to connect the lower portion of the outer peripheral surface of the terminal portion and the lower portion of the inner peripheral surface of the flange portion.

[0037] <Comparative Example 2> A battery case was produced in the same manner as in Example 1, except that the thin-walled portion of the sealing plate was formed so as to connect the central portion of the outer peripheral surface of the terminal portion and the central portion of the inner peripheral surface of the flange portion.

[0038] <Comparative Example 3> A battery case was produced in the same manner as in Example 1, except that the thin-walled portion of the sealing plate was formed so as to connect the upper portion of the outer peripheral surface of the terminal portion and the upper portion of the inner peripheral surface of the flange portion.

[0039] [Observation of the Cross-Section of the Sealing Plate] Among the battery cases produced as described above, the sealing plate was embedded in an epoxy resin, and after the epoxy resin was cured, it was cut so that the cross-section of the sealing plate appeared, and the cross-section of the sealing plate was observed. The results are summarized in Table 1 together with the shape and connection position of the thin-walled portion.

[0040] [Table 1]

[0041] In Example 1, there was almost no deformation of the thin-walled portion, and there was also almost no fluctuation in the vertical position of the terminal portion. In Example 2, the thin-walled portion was slightly deformed so as to change from an inclined state to a horizontal state, and the vertical position of the terminal portion moved slightly upward. In Comparative Examples 1 and 3, the thin-walled portion was deformed so as to change from an inclined state to a horizontal state, and the vertical position of the terminal portion moved significantly upward. In Comparative Example 2, the thin-walled portion was significantly deformed, and the vertical position of the terminal portion moved significantly.

[0042] From the above results, it can be seen that it is preferable that the thin-walled portion inclines upward from the inner side to the outer side in the radial direction of the sealing plate and is connected downward from the central portion of the outer peripheral surface of the terminal portion and upward from the central portion of the inner peripheral surface of the flange portion. Furthermore, since the effect of suppressing deformation of the thin-walled portion in Example 1 is remarkable, it can be seen that it is more preferable that the thin-walled portion is connected to the lower portion of the outer peripheral surface of the terminal portion and the upper portion of the inner peripheral surface of the flange portion.

Explanation of Reference Numerals

[0043] 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 Exterior can, 20A Bottom surface portion, 20B Side surface portion, 20C Groove portion, 20D Caulked portion, 21 Gasket, 30 Sealing plate, 31 Flange portion, 31A Inner peripheral surface, 32 Terminal portion, 32A Outer peripheral surface, 33 Thin-walled portion, 33A Inner end portion, 33B Outer end portion

Claims

1. A cylindrical battery having an electrode body in which a positive electrode plate and a negative electrode plate are wound with a separator interposed therebetween, an electrolyte, a bottomed cylindrical exterior can housing the electrode body and the electrolyte, and a sealing plate closing an opening of the exterior can, wherein the sealing plate has a flange portion caulked and fixed to the opening of the exterior can, a terminal portion formed radially inward of the flange portion, and a thin portion connecting the flange portion and the terminal portion, the thin portion is formed to incline upward from the radially inner side to the outer side of the sealing plate, and when the outer peripheral surface of the terminal portion and the inner peripheral surface of the flange portion are each divided into three equal parts in the vertical direction into an upper portion, a central portion, and a lower portion, it is formed to connect only the lower portion of the outer peripheral surface of the terminal portion and only the upper portion of the inner peripheral surface of the flange portion, a cylindrical battery.

2. The cylindrical battery according to Claim 1, wherein the thin portion is formed to taper from the radially inner side to the outer side of the sealing plate, a cylindrical battery.

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