Battery can and battery using same

Abstract

A battery can 10 according to the present disclosure comprises: a bottom part 12; a cylindrical trunk part 14 that extends from the bottom part 12; and an opening end part 16 that is continuous with the trunk part 14. The opening end part 16 includes an opening end face 16p, an outer peripheral face 16q, and an inner peripheral face 16r. The opening end face 16p is formed by the surface of a base material 22 that is not provided with a plating layer 20. The inner peripheral face 16r includes a tapered face 16t inclined with respect to the opening end face 16p and the outer peripheral face 16q such that the thickness of the opening end part 16 decreases toward the opening end face 16p.

Description

Battery can and battery using same

[0001] The present disclosure relates to a battery can and a battery using the same.

[0002] Metal battery cans are widely used in batteries such as lithium-ion secondary batteries, nickel-metal hydride batteries, and alkaline batteries.

[0003] Patent Literature 1 describes an example of a method for manufacturing a battery can. The battery can is manufactured using a steel sheet having a plating layer. The steel sheet is formed into the shape of the battery can by drawing, and then the open edge is trimmed.

[0004] Japanese Patent Application Laid-Open No. 2004-220863

[0005] As described in Patent Document 1, trimming the open end removes the plating layer, exposing the base material of the steel sheet to the surface. When the base material of the steel sheet, i.e., the steel, is exposed to the surface, the exposed portion may come into contact with an electrolyte, condensed water, or air, causing rust.

[0006] As described in Patent Document 1, the formation of rust can be prevented by reforming the plating layer after trimming. However, since plating each and every battery can formed into a predetermined shape is cumbersome, such a method is difficult to adopt from the standpoints of cost and mass productivity.

[0007] The present disclosure provides a battery can that can suppress the occurrence of rust with a simple configuration, and a battery using the same.

[0008] The present disclosure provides a battery can comprising: a bottom; a cylindrical body extending from the bottom; and an open end continuing to the body, wherein the open end includes an open end surface, an outer circumferential surface, and an inner circumferential surface, the open end surface being formed by a surface of a base material not provided with a plating layer, and the inner circumferential surface including a tapered surface inclined with respect to the open end surface and the outer circumferential surface such that the thickness of the open end decreases toward the open end surface.

[0009] According to the technology of the present disclosure, it is possible to provide a battery can that can suppress the occurrence of rust with a simple configuration, and a battery using the same.

[0010] FIG. 1 is a cross-sectional view of a battery can according to Embodiment 1. FIG. 2 is a partially enlarged view of FIG. 1. FIG. 3 is a process diagram showing a method for manufacturing a battery can. FIG. 4 is a cross-sectional view of a battery according to Embodiment 2. FIG. 5 is a partially enlarged view of FIG. 4. FIG. 6A is a diagram illustrating the operation of a battery according to the present disclosure. FIG. 6B is a diagram illustrating the operation of a conventional battery. FIG. 7 is a partially enlarged cross-sectional view of a battery can according to a modified example.

[0011] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. The present disclosure is not limited to the following embodiments.

[0012] (Embodiment 1) Fig. 1 is a cross-sectional view of a battery can according to embodiment 1. Fig. 2 is a partially enlarged view of Fig. 1. The cross sections of Figs. 1 and 2 are cross sections including the central axis O of the battery can 10.

[0013] The battery can 10 is a molded body of a plate-shaped base material 22 having a plating layer 20 formed on its surface, and includes a bottom 12, a body 14, and an opening end 16. The plating layer 20 serves to suppress corrosion of the base material 22. The plating layer 20 is, for example, a Ni plating layer. The base material 22 is a metal plate such as a steel plate. The body 14 is a cylindrical portion extending vertically from the bottom 12. The opening end 16 is a portion continuing from the body 14 and is a portion that should be bent toward the inside of the battery can 10 to seal the battery can 10.

[0014] The opening end 16 includes an opening end surface 16p, an outer peripheral surface 16q, and an inner peripheral surface 16r. The opening end surface 16p is an annular surface exposed to the outside of the final battery. The opening end surface 16p is formed by the surface of the base material 22 on which the plating layer 20 is not provided. In this embodiment, the entire opening end surface 16p is formed by the surface of the base material 22. The outer peripheral surface 16q is the surface exposed to the outside of the final battery. The inner peripheral surface 16r is the surface exposed to the inside of the final battery or in contact with the sealing body. The inner peripheral surface 16r includes a tapered surface 16t that is inclined with respect to the opening end surface 16p and the outer peripheral surface 16q so that the thickness of the opening end 16 decreases toward the opening end surface 16p. The opening end 16 is composed of a portion with a constant thickness and a portion whose thickness gradually decreases toward the opening end surface 16p. With this configuration, compared to a battery can without tapered surface 16t, the area of ​​opening end surface 16p without plating layer 20 can be reduced, thereby suppressing the occurrence of rust. There is no need to form a new plating layer on opening end surface 16p, and rust can be suppressed with a simple configuration.

[0015] In the present embodiment, the outer peripheral surface 16q and the inner peripheral surface 16r are each a plated surface formed by the plating layer 20. The tapered surface 16t, which is a part of the inner peripheral surface 16r, is also a plated surface formed by the plating layer 20. This configuration can also suppress the occurrence of rust on the tapered surface 16t. It is desirable that the entire surface of the battery can 10, excluding the opening end surface 16p, is a plated surface formed by the plating layer 20.

[0016] The thickness T1 of the opening end 16 at the position of the opening end surface 16p is adjusted to, for example, 80% or less of the thickness T2 of the opening end 16 at the portion where the tapered surface 16t is not provided. By appropriately adjusting the thickness T1, the rust suppression effect is enhanced. The ratio (T1 / T2) of the thickness T1 to the thickness T2 is, for example, 10% or more and 80% or less, and preferably 10% or more and 50% or less, in percentage. By adjusting the ratio (T1 / T2) within this range, the rust suppression effect can be sufficiently obtained while avoiding a complicated process for forming the tapered surface 16t. The thickness T1 is equal to the width of the opening end surface 16p. The thickness T2 is equal to the thickness of the body portion 14 of the battery can 10.

[0017] The position of the upper end of the tapered surface 16t coincides with the opening end surface 16p. The position of the lower end of the tapered surface 16t is not particularly limited. The length L1 of the tapered surface 16t is adjusted, for example, in the range of 0.3 mm to 1 mm. By ensuring an appropriate length L1, the process of forming the tapered surface 16t can be prevented from becoming complicated. The length L1 of the tapered surface 16t refers to the length in the direction perpendicular to the thickness direction of the opening end 16.

[0018] In this embodiment, the outer peripheral surface 16q is not tapered, and the outer peripheral surface 16q and the opening end surface 16p form a roughly 90-degree corner. At first glance, it may seem that the same effect can be achieved by providing a tapered surface on the outer peripheral surface 16q instead of the inner peripheral surface 16r. However, providing a tapered surface on the outer peripheral surface 16q could cause problems in the process of bending the opening end 16 inward to attach a sealing cap to the opening end 16, or problems due to changes in the external dimensions of the battery. This embodiment makes such problems less likely to occur.

[0019] There are no particular limitations on the shape of the battery can 10. The battery can 10 has, for example, a cylindrical, rectangular, or elliptical cylindrical shape, and is typically cylindrical.

[0020] 3 is a process diagram showing the manufacturing method of the battery can 10. In step S1, a plate-shaped base material 22 is drawn. The plate-shaped base material 22 is a plated steel plate, and is pre-processed to a predetermined size taking into account the final shape of the battery can 10. In the drawing process, the plate-shaped base material 22 is set in a mold, and a punch is pressed against the plate-shaped base material 22 to plastically deform the plate-shaped base material 22 into a cylindrical shape. If necessary, the formed body obtained by the drawing process may be subjected to ironing.

[0021] Next, in step S2, the open end of the formed body is trimmed. After the drawing process in step S1, a flange-shaped portion is formed at the open end of the formed body. The flange-shaped portion is the portion that is gripped by the die during the drawing process. Trimming is a process for cutting and removing the flange-shaped portion. The cut surface formed by trimming is the surface of the base material 22 on which no plating layer is provided.

[0022] Finally, in step S3, the tapered surface 16t is formed. One method for forming the tapered surface 16t is to press the open end of the molded body. By pressing, the plating layer 20 remains on the tapered surface 16t.

[0023] The step of trimming the open end of the molded body and the step of forming the tapered surface 16t may be carried out simultaneously.

[0024] (Embodiment 2) Figure 4 is a cross-sectional view of a battery according to Embodiment 2. The battery 100 includes a battery can 10 and an electrode group 4. The battery can 10 is the same as that described in Embodiment 1. A sealing body 24 is attached to an open end 16 so as to seal the interior of the battery 100. The open end 16 is bent to secure the sealing body 24 to the battery can 10. The sealing body 24 includes a lid 2 and a gasket 3. The lid 2 serves as a terminal and a safety valve. The gasket 3 is an annular member made of an insulating material such as resin. The gasket 3 is disposed between the lid 2 and the open end 16 of the battery can 10.

[0025] The battery can 10 houses an electrode group 4. The electrode group 4 has a wound structure. The electrode group 4 includes a positive electrode 5, a negative electrode 6, and a pair of separators 7. The electrode group 4 is impregnated with an electrolyte. The positive electrode 5 includes a positive electrode current collector 5a and a positive electrode active material layer 5b. One end of a positive electrode lead 5c is connected to the positive electrode 5. The other end of the positive electrode lead 5c is connected to the back surface of the lid 2. The negative electrode 6 includes a negative electrode current collector 6a and a negative electrode active material layer 6b. One end of a negative electrode lead 6c is connected to the negative electrode 6. The other end of the negative electrode lead 6c is connected to the bottom surface of the battery can 10. Insulating rings 8 are disposed on the top and bottom surfaces of the electrode group 4, respectively.

[0026] Fig. 5 is a partially enlarged view of Fig. 4. The open end 16 of the battery can 10 is bent and pressed against the gasket 3. The inner peripheral surface 16r of the open end 16 is in close contact with the gasket 3. This seals the inside of the battery 100. In the example shown in Fig. 5, the entire tapered surface 16t is in close contact with the gasket 3.

[0027] As shown in FIG. 5 , in this embodiment, the opening end 16 of the battery can 10 includes a rounded portion 161 curved toward the central axis O of the battery can 10 and a straight portion 162 extending from the rounded portion 161 and contacting the upper surface of the sealing body 24. The tapered surface 16t of the opening end 16 is formed only on the straight portion 162. By limiting the area where the tapered surface 16t is formed to the straight portion 162, the airtightness of the interior of the battery 100 is reliably ensured. Furthermore, the rounded portion 161 is a portion of the battery can 10 where stress concentrates. If the rounded portion 161 does not have a tapered surface 16t, the thickness of the rounded portion 161 can be sufficiently ensured. This reduces the possibility of stress corrosion cracking of the plating layer 20 at the rounded portion 161.

[0028] The length of the straight portion 162 is, for example, 0.5 mm to 1.5 mm. It is also desirable that the length L1 (FIG. 2) of the tapered surface 16t be 0.3 mm to 1.0 mm.

[0029] FIG. 6A is a diagram illustrating the operation of the battery 100 of this embodiment. As shown in FIG. 6A , the battery 100 of this embodiment uses the battery can 10 of embodiment 1. The inner circumferential surface 16r of the opening end 16 of the battery can 10 includes a tapered surface 16t. The tapered surface 16t reduces the area of ​​the opening end surface 16p. With the battery 100 of this embodiment, even if a liquid W such as water or an electrolyte solution accumulates on the upper surface of the sealing body 24, the contact area between the liquid W and the opening end surface 16p is small. Therefore, even if the opening end surface 16p is formed by the surface of the base material 22 on which no plating layer is provided, rust generation can be minimized.

[0030] When the opening end 16 is bent and pressed against the gasket 3, a part of the opening end surface 16p bites into the gasket 3. When the area of ​​the opening end surface 16p is small, the ratio of the area of ​​the part biting into the gasket 3 to the area of ​​the opening end surface 16p is large. This also works advantageously to suppress rust.

[0031] 6B is a diagram illustrating the operation of a conventional battery. When the opening end 116 of the battery can is not provided with a tapered surface, the opening end 116 has a constant thickness up to the opening end surface 116p. In this case, the contact area between the opening end surface 116p and the liquid W is large. Therefore, there is a possibility that an amount of rust will occur corresponding to the large area of ​​the opening end surface 116p.

[0032] (Modification) Fig. 7 is a partially enlarged cross-sectional view of a battery can 11 according to a modification. In the battery can 11, the tapered surface 16t is formed by the surface of the base material 22 on which the plating layer 20 is not provided. As can be seen from Figs. 5 and 6A, the tapered surface 16t of the opening end 16 is the surface that comes into close contact with the gasket 3. Therefore, even if the plating layer 20 does not exist in a position corresponding to the tapered surface 16t, the tapered surface 16t is unlikely to rust. Even if rust does occur, it is unlikely to become a technical problem because the gasket 3 and the tapered surface 16t are in close contact with each other.

[0033] In this modification, the tapered surface 16t can be formed by grinding and / or polishing in step S3 shown in Fig. 3. When the tapered surface 16t is formed by grinding and / or polishing, the plating layer 20 is removed, and the battery can 11 of this modification is obtained. The battery can 11 of this modification may be easier to manufacture than the battery can 10 of the first embodiment.

[0034] (Other Embodiments) (Additional Notes) The above description of the embodiments discloses the following techniques.

[0035] (Technology 1) A battery can comprising: a bottom; a cylindrical body extending from the bottom; and an open end continuing to the body, wherein the open end includes an open end surface, an outer circumferential surface, and an inner circumferential surface, wherein the open end surface is formed by a surface of a base material not provided with a plating layer, and the inner circumferential surface includes a tapered surface that is inclined with respect to the open end surface and the outer circumferential surface such that the thickness of the open end decreases toward the open end surface.

[0036] According to the technology of the present disclosure, it is possible to provide a battery can that can suppress the occurrence of rust with a simple configuration.

[0037] (Technology 2) The battery can according to Technology 1, wherein the tapered surface is a plated surface formed by a plating layer. With this configuration, rust can be prevented from occurring on the tapered surface.

[0038] (Technology 3) The battery can according to Technology 1, wherein the tapered surface and the opening end surface are formed by a surface of the base material on which no plating layer is provided. Such a battery can may be easily manufactured.

[0039] (Technology 4) A battery comprising: a battery can; an electrode group housed in the battery can; and a sealing body attached to the battery can, wherein the battery can is the battery can according to any one of Technologies 1 to 3.

[0040] According to the technology of the present disclosure, it is possible to provide a battery that can suppress the occurrence of rust with a simple configuration.

[0041] (Technology 5) The battery according to Technology 4, wherein the open end of the battery can includes a rounded portion curved toward the center of the battery can and a straight portion extending from the rounded portion and contacting the upper surface of the sealing body, and the tapered surface is formed only on the straight portion. With this configuration, it is possible to reduce the possibility of stress corrosion cracking of the plating layer in the rounded portion.

[0042] The technology of the present disclosure is useful for batteries that use metal containers.

Claims

1. A battery can comprising: a bottom; a cylindrical body extending from the bottom; and an open end continuing from the body, wherein the open end includes an open end surface, an outer peripheral surface, and an inner peripheral surface, wherein the open end surface is formed by a surface of a base material not provided with a plating layer, and the inner peripheral surface includes a tapered surface that is inclined relative to the open end surface and the outer peripheral surface such that the thickness of the open end decreases toward the open end surface.

2. The battery can according to claim 1, wherein the tapered surface is a plated surface formed by a plating layer.

3. The battery can according to claim 1, wherein the tapered surface and the open end surface are formed by a surface of the base material that is not provided with a plating layer.

4. A battery comprising: a battery can; an electrode group housed in the battery can; and a sealing body attached to the battery can, wherein the battery can is the battery can defined in claim 1.

5. The battery according to claim 4, wherein the open end of the battery can includes a rounded portion curved toward the center of the battery can and a straight portion extending from the rounded portion and contacting the upper surface of the sealing body, and the tapered surface is formed only on the straight portion.

Images