Battery

Abstract

A battery 100 according to the present disclosure comprises: a battery can 10 including a bottom portion 13, a cylindrical body portion 14 extending from the bottom portion 13, and an opening 16 following the body portion 14; an electrode assembly 4 housed in the battery can 10; and a sealing body 24 attached to the opening 16. The sealing body 24 includes a lid body 2 and a gasket 3 disposed between the lid body 2 and the opening 16. The opening 16 includes an end surface 16p having an opening end edge 16s of the battery can 10, and the end surface 16p is formed by the surface of a base material on which a plating layer is not provided. The inner peripheral surface 16r of the opening 16 includes a tapered surface 16t inclined with respect to the outer peripheral surface 16q of the opening 16 such that the thickness of the opening 16 decreases toward the opening end edge 16s. A portion of the opening 16 bites into the gasket 24, and the entire surface of the end surface 16p is in contact with and covered by the gasket 24.

Description

Battery

[0001] This disclosure relates to a battery.

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

[0003] Patent Document 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. After forming the steel sheet into the shape of a battery can by drawing, a trimming process is applied to the opening.

[0004] Patent Document 2 describes a sealed square non-aqueous electrolyte battery in which a sealing lid group including a packing, a holding plate, an overcurrent heating protection element, and a terminal plate is held at the outer mounting can opening portion at the outer pedestal portion of the packing, and is drawn from the outside to the inside between the thick portions of the packing, and the openings of the outer mounting can and the packing are bent inward around the upper protruding portion of the holding plate, the overcurrent heating protection element, and the terminal plate.

[0005] Japanese Patent Application Laid-Open No. 2004-220863 Japanese Patent Application Laid-Open No. 8-138727

[0006] As described in Patent Document 1, when trimming the opening, the plating layer is removed and the base material of the steel sheet is exposed on the surface. When the base material of the steel sheet, that is, steel, is exposed on the surface, the exposed portion may come into contact with an electrolytic solution, condensed water, or air, resulting in rust.

[0007] As described in Patent Document 1, if the plating layer is reformed after the trimming process, the occurrence of rust can be prevented. However, since it is complicated to apply a plating process to each of the battery cans formed into a predetermined shape, such a method is difficult to adopt from the viewpoints of cost and mass productivity.

[0008] Patent Document 2 illustrates a square battery in which the opening end face of the outer mounting can appears to be covered by a packing. If the exposed portion where the plating layer is removed is covered by the packing, it is possible to suppress the occurrence of rust when the exposed portion comes into contact with an electrolytic solution, condensed water, or air. However, in reality, it is not easy to completely cover the opening end face of the outer mounting can by conventional bending, and it is considered that the battery disclosed in Patent Document 2 does not suppress the occurrence of rust.

[0009] This disclosure provides a battery that can suppress the occurrence of rust with a simple configuration.

[0010] This disclosure provides a battery comprising: a battery can including a bottom, a cylindrical body extending from the bottom, and an opening continuing from the body; a group of electrodes housed in the battery can; and a sealing body attached to the opening of the battery can to seal the battery can, wherein the sealing body includes a lid and a gasket disposed between the lid and the opening; the opening includes an end face having an open edge of the battery can, the end face is formed by the surface of a base material without a plating layer, the inner circumferential surface of the opening includes a tapered surface inclined with respect to the outer circumferential surface of the opening such that the thickness of the opening decreases toward the open edge, a portion of the opening bites into the gasket, and the entire surface of the end face abuts against and covers the gasket.

[0011] The technology disclosed herein provides a battery that can suppress the occurrence of rust with a simple configuration.

[0012] Figure 1 is a cross-sectional view of a battery according to Embodiment 1. Figure 2 is a partially enlarged view of Figure 1. Figure 3 is a partially enlarged view of Figure 2. Figure 4A is a diagram illustrating the operation of the battery of this disclosure. Figure 4B is a diagram illustrating the operation of a conventional battery. Figure 5 is a process diagram showing a method for manufacturing a battery. Figure 6 is a cross-sectional view of a molded body in the manufacturing method of a battery. Figure 7 is a partially enlarged cross-sectional view of a modified battery. Figure 8 is a partially enlarged cross-sectional view of a battery according to another modified battery.

[0013] The embodiments of this disclosure will be described below with reference to the drawings. This disclosure is not limited to the embodiments described below.

[0014] (Embodiment 1) Figure 1 is a cross-sectional view of a battery according to Embodiment 1. The cross-section in Figure 1 includes the central axis of the battery 100. The battery 100 comprises a battery case 10, an electrode group 4, and a sealing body 24. The electrode group 4 is housed in the battery case 10. The sealing body 24 seals the battery case 10 so as to seal the battery 100.

[0015] The battery can 10 comprises a bottom portion 13, a body portion 14, and an opening 16. The body portion 14 is a cylindrical portion extending vertically from the bottom portion 13. The opening 16 is a portion that continues from the body portion 14. A sealing body 24 is attached to the opening 16, and the upper and lower surfaces of the peripheral edge of the sealing body 24 are sandwiched by the opening 16. The opening 16 includes a curved portion 161 that is bent inward toward the inside of the battery can 10. The opening end edge 16s of the battery can 10, which is the end of the opening 16, is located on the peripheral edge of the sealing body 24. The sealing body 24 includes a lid 2 and a gasket 3. The gasket 3 is positioned between the lid 2 and the opening 16.

[0016] Figure 2 is a partially enlarged view of Figure 1. Figure 3 is a partially enlarged view of Figure 2. The battery can 10 is a molded body of a plate-shaped base material 22 with a plating layer 20 on its surface. The plating layer 20 plays a role in suppressing 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 opening 16 includes an end face 16p, an outer peripheral surface 16q, and an inner peripheral surface 16r. The end face 16p is an annular surface and includes the opening edge 16s. The opening edge 16s is the annular edge of the battery can 10 that is furthest from the bottom 13 in the direction in which the body 14 and the opening 16 extend from the bottom 13. The end face 16p is the end surface of the opening 16, that is, the surface furthest from the bottom 13 in the direction in which the body 14 and the opening 16 extend from the bottom 13. Therefore, when the part furthest from the bottom 13 is a surface, the opening edge 16s coincides with the end face 16p.

[0017] The end face 16p is formed by the surface of the base material 22, which does not have the plating layer 20. In this embodiment, the entire end face 16p is formed by the surface of the base material 22. The outer circumferential surface 16q is the surface exposed to the outside in the battery 100. The inner circumferential surface 16r is the surface exposed to the inside of the battery 100 or in contact with the sealing body 24 (gasket 3). The inner circumferential surface 16r includes a tapered surface 16t that is inclined with respect to the outer circumferential surface 16q such that the thickness of the opening 16 decreases toward the opening edge 16s. In the battery 100, the upper end of the tapered surface 16t is located on the outer circumferential surface 16q and coincides with the opening edge 16s of the battery can 10. Therefore, in the battery can 10, the tapered surface 16t is the end face 16p of the opening 16. The outer circumferential surface 16q is a plated surface formed by the plating layer 20. The portion of the inner circumferential surface 16r excluding the tapered surface 16t (end face 16p in Figure 3) is a plated surface formed by the plating layer 20. The tapered surface 16t, which is the end face 16p, is a surface formed by the surface of the base material 22 where the plating layer 20 is not provided. The entire surface of the battery can 10, excluding the end face 16p, may be a plated surface formed by the plating layer 20.

[0018] In this embodiment, a portion of the opening 16 of the battery can 10, including the end face 16p, is embedded in the gasket 3. More specifically, a portion of the opening 16 at the periphery of the sealing body 24 is embedded in the gasket 3. As a result, the entire surface of the end face 16p is in contact with and covered by the gasket 3. With this configuration, since the end face 16p is not exposed on the surface of the battery 100, electrolyte, condensation, or air is less likely to come into contact with the end face 16p. Therefore, there is no need to form another plating layer on the end face 16p, and rust can be suppressed with a simple configuration.

[0019] The opening 16 of the battery can 10 is provided with a tapered surface 16t, which allows the opening to be composed of a portion of constant thickness and a portion of gradually decreasing thickness towards the opening edge 16s. With this configuration, the end face 16p can be easily fitted into the gasket 3 compared to a battery can without a tapered surface 16t. Therefore, the battery 100 of this embodiment can easily and reliably suppress the occurrence of rust.

[0020] The sealing body 24 is crimped and fixed to the opening 16 such that the upper and lower surfaces of the peripheral edge of the lid 2 are sandwiched by the gasket 3. The opening 16 of the battery can 10 is bent and pressed against the gasket 3. The gasket 3 is positioned between the lid 2 and the opening 16 of the battery can 10. The inner circumferential surface 16r of the opening 16 is in close contact with the gasket 3. This seals the inside of the battery 100. In this embodiment, a part of the opening 16 bites into the gasket 3, so that the inner circumferential surface 16r of the opening 16, through the end face 16p and the opening edge 16s, is in close contact with the gasket 3 up to a part of the outer circumferential surface 16q.

[0021] In the battery 100, the opening 16 bites into the gasket 3, so that the entire end face 16p and a portion of the outer peripheral surface 16q are in contact with the gasket 3. More specifically, the entire tapered surface 16t, which is the end face 16p, the opening edge 16s, and a portion of the outer peripheral surface 16q are in contact with and covered by the gasket 3. With this configuration, the electrolyte, condensation, or air is less likely to come into contact with the end face 16p, and rust generation can be further suppressed with a simple configuration.

[0022] As described above, in the battery 100, the upper end of the tapered surface 16t is located on the outer peripheral surface 16q and coincides with the opening edge 16s of the battery can 10. That is, the tapered surface 16t is the end surface 16p and is formed by the surface of the base material 22 which does not have the plating layer 20. With this configuration, the end surface 16p (tapered surface 16t) can be easily fitted into the gasket 3 and covered with the gasket 3. Therefore, the electrolyte, condensation, or air is less likely to come into contact with the end surface 16p, and the occurrence of rust can be further suppressed with a simple configuration. In addition, a battery can 10 having such a configuration may be easy to manufacture, which may be advantageous in the manufacturing process of the battery 100.

[0023] The position of the lower end of the tapered surface 16t is not particularly limited. It is desirable to make the length L1 of the tapered surface 16t as short as possible. The length L1 is adjusted, for example, to be greater than or equal to the maximum thickness of the opening 16 and less than or equal to the length of the straight portion 162 described later. By ensuring an appropriate length L1 of the tapered surface 16t, it is possible to avoid making the process of forming the tapered surface 16t complicated. The length L1 of the tapered surface 16t refers to the length in the direction perpendicular to the thickness direction of the opening 16.

[0024] It is preferable that the outer circumferential surface 16q does not have a tapered surface. If a tapered surface is provided on the outer circumferential surface 16q, problems may arise in the process of bending the opening 16 inward and attaching the sealing body 24 to the opening 16, or problems may arise due to changes in the external dimensions of the battery 100. According to this embodiment, such problems are less likely to occur.

[0025] As shown in Figure 2, in this embodiment, the opening 16 of the battery can 10 includes a curved portion 161 that curves toward the central axis of the battery can 10 and a straight portion 162 that extends from the curved portion 161 and contacts the upper surface of the sealing body 24. The tapered surface 16t of the opening 16 is not formed in the curved portion 161, but only in the straight portion 162. By limiting the formation range of the tapered surface 16t to the straight portion 162, the airtightness inside the battery 100 is reliably ensured. Furthermore, the curved portion 161 is a part of the battery can 10 where stress is concentrated. If the tapered surface 16t is not provided in the curved portion 161, sufficient wall thickness can be ensured in the curved portion 161. Therefore, the possibility of stress corrosion cracking of the plating layer 20 in the curved portion 161 can be reduced.

[0026] The length of the straight section 162 is, for example, 0.5 mm or more and 1.5 mm or less.

[0027] 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 has a positive electrode current collector 5a and a positive electrode active material layer 5b. One end of the 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 cover 2. The negative electrode 6 has a negative electrode current collector 6a and a negative electrode active material layer 6b. One end of the 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 arranged on the upper and lower surfaces of the electrode group 4, respectively.

[0028] The lid 2 of the sealing body 24 seals the battery can 10 via the gasket 3. The lid 2 serves as both a terminal and a safety valve. The structure of the lid 2 is not particularly limited as long as it can seal the inside of the battery 100 via the gasket 3; for example, it may be a structure in which multiple components, such as a component that acts as a terminal and a component that acts as a safety valve, are stacked. The gasket 3 is an annular component made of an insulating material such as resin.

[0029] The shape of the battery 100 is not particularly limited. The battery 100 may have, for example, a cylindrical, rectangular, or elliptical shape, and is typically cylindrical. That is, the battery casing 10 is typically cylindrical.

[0030] Figure 4A is a diagram illustrating the operation of the battery 100 of this embodiment. According to the battery 100 of this embodiment, even if a liquid W such as water or electrolyte accumulates on the upper surface of the sealing body 24, the end face 16p is in contact with and covered by the gasket 3, so contact between the liquid W and the end face 16p is prevented. Therefore, even if the end face 16p is formed by the surface of the base material 22 which does not have a plating layer, the occurrence of rust can be minimized. Even if rust does occur, the end face 16p is embedded in the gasket 3 and is not exposed on the surface of the battery 100, so it is unlikely to cause problems.

[0031] Figure 4B is a diagram illustrating the operation of a conventional battery. If the opening 116 of the battery case does not include a tapered surface, the end face 116p is not covered by the gasket 3, and the end face 116p comes into contact with the liquid W. As a result, rust may occur.

[0032] Figure 5 is a process diagram showing an example of a method for manufacturing a battery 100. In step S1, a plate-shaped base material 22 is subjected to deep drawing. The plate-shaped base material 22 is a plated steel sheet and has been pre-processed to a predetermined size considering the final shape of the battery can 10. In the deep 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 it into a cylindrical shape. If necessary, the molded body obtained by deep drawing may be subjected to ironing.

[0033] Next, in step S2, the opening of the molded body is trimmed. After the drawing process in step S1, a flange-like portion is formed in the opening of the molded body. The flange-like portion is the part that was gripped by the die during the drawing process. Trimming is a process to cut and remove this flange-like portion. The cut surface formed by trimming is the surface of the base material 22 that does not have a plating layer.

[0034] Next, in step S3, a tapered surface 16t, i.e., an end surface 16p, is formed. One method for forming the tapered surface 16t is to grind and / or polish the opening of the molded body. When the tapered surface 16t is formed by grinding and / or polishing, the plating layer 20 is removed, and the tapered surface 16t becomes the surface of the base material 22 that does not have the plating layer 20. Here, the step of trimming the opening of the molded body and the step of forming the tapered surface 16t may be performed simultaneously. For example, the tapered surface 16t may be formed simultaneously by trimming the opening of the molded body. This reduces the number of steps and makes it easier to manufacture the battery can 10.

[0035] Figure 6 is a cross-sectional view of a molded body 30 in which a tapered surface 16t, which is the end face 16p, is formed in step S3 of the manufacturing method of the battery 100. The molded body 30 is the battery can 10 before the battery 100 is assembled. The cross-section in Figure 6 is a cross-section including the central axis of the molded body 30. The molded body 30 comprises a bottom portion 33, a cylindrical body portion 34 extending vertically from the bottom portion 33, and an opening 36 continuing from the body portion 34. The opening 36 includes an outer circumferential surface 36q, an inner circumferential surface 36r, and an end face 36p. The end face 36p is a tapered surface 36t which is part of the inner circumferential surface 36r that is inclined with respect to the outer circumferential surface 36q such that the inner diameter increases towards the top of the molded body 30. The upper end of the tapered surface 36t is located on the outer circumferential surface 36q and coincides with the opening edge 36s of the molded body 30. The end face 36p is formed by the surface of the base material 22 which does not have a plating layer 20. The outer circumferential surface 36q and the inner circumferential surface 36r are plated surfaces formed by the plating layer 20, respectively.

[0036] Next, in step S4, the electrode group 4 is housed in the molded body 30. When housing the electrode group 4, the negative electrode lead 6c connected to the electrode group 4 may be connected to the molded body 30. For example, after housing the electrode group 4 in the molded body 30, the insulating ring 8 is inserted into the molded body 30 and placed on top of the electrode group 4. Then, the electrolyte is poured into the molded body 30.

[0037] Finally, in step S5, the battery can 10 (molded body 30) is sealed with a sealing body 24. The sealing is performed, for example, by crimping and fixing the sealing body 24 to the opening 16. At this time, a part of the opening 16 is made to bite into the gasket 3 of the sealing body 24, so that the end face 16p abuts against and covers the gasket 3. For example, when performing this sealing, a top mold having a flat surface that is more inclined toward the sealing body 24 than conventional molds is used for crimping and fixing, and the inclination of the straight portion 162 of the opening 16 with respect to the upper surface of the sealing body 24 is made steeper, so that a part of the opening 16, including the entire end face 16p, bites into the gasket 3 of the sealing body 24.

[0038] In this way, battery 100 is obtained.

[0039] (Modified Version) Figure 7 is a partially enlarged cross-sectional view of a modified battery 110. In the battery 110, the vicinity of the end face 16p of the opening 16 of the battery can 11 is bent in a hook shape so as to bite into the gasket 3. The battery can 11 can bite into the gasket 3 with its end face 16p while the radius of curvature of the rounded portion 161 (see Figure 2) of the opening 16 is larger than that of the battery can 10. Therefore, the battery 110 can suppress the occurrence of rust without significantly changing the curvature of the rounded portion 161 from that of a conventional battery. This configuration can be obtained by, for example, using an upper die that is hook-shaped so that the end of the opening 16 bites into the gasket 3 when sealing the battery can 11 with the sealing body 24 in step S5 shown in Figure 5.

[0040] Figure 8 is a partially enlarged cross-sectional view of a battery 120 according to another modified example. In the battery 120, the upper end of the tapered surface 16t at the opening 16 of the battery can 12 coincides with the end face 16p. That is, the opening 16 of the battery can 12 independently includes the end face 16p and the tapered surface 16t provided on the inner circumferential surface 16r. In the battery can 12, the thickness of the opening 16 at the position of the end face 16p is, for example, more than 0% and 50% or less of the thickness of the opening 16 in the portion where the tapered surface 16t is not provided, preferably more than 0% and 40% or less, and more preferably more than 0% and 20% or less. In this case, the thickness of the opening 16 at the position of the end face 16p is equal to the width of the end face 16p. The thickness of the opening 16 in the portion where the tapered surface 16t is not provided is equal to the thickness of the body portion 14 of the battery can 10. When the upper end of the tapered surface 16t coincides with the end surface 16p, the smaller the thickness of the opening 16 at the position of the end surface 16p, the easier it is for the end surface 16p to bite into the gasket 3, and the easier it is for the end surface 16p to be covered by the gasket 3. Therefore, the occurrence of rust can be suppressed more easily. In this case, the tapered surface 16t, which is part of the inner circumferential surface 16r, may be a surface formed by the surface of the base material 22 that does not have a plating layer 20. Such a configuration can be obtained, for example, by the manufacturing method described above.

[0041] In this modified example, the tapered surface 16t may be a plated surface provided with the plating layer 20. According to such a configuration, the occurrence of rust on the tapered surface 16t can be further suppressed. The tapered surface 16t that is the plated surface can be formed by pressing the opening of the molded body in step S3 shown in FIG. 5. According to the pressing process, the plating layer 20 remains on the inner peripheral surface 16r (tapered surface 16t).

[0042] (Other Embodiments) (Appended Note) The following techniques are disclosed by the description of the above embodiments.

[0043] (Technique 1) A battery can, including a bottom portion, a cylindrical body portion extending from the bottom portion, and an opening following the body portion; an electrode group housed in the battery can; and a sealing body attached to the opening of the battery can to seal the battery can, the sealing body including a lid body and a gasket disposed between the lid body and the opening, the opening including an end surface having an opening edge of the battery can, the end surface being formed by the surface of a base material without a plating layer provided thereon, the inner peripheral surface of the opening including a tapered surface inclined with respect to the outer peripheral surface of the opening such that the thickness of the opening decreases toward the opening edge, a part of the opening biting into the gasket, and the entire surface of the end surface being in contact with and covered by the gasket.

[0044] According to the technique of the present disclosure, a battery capable of suppressing the occurrence of rust with a simple configuration can be provided.

[0045] (Technique 2) The battery according to Technique 1, wherein the entire surface of the end surface and a part of the outer peripheral surface are in contact with and covered by the gasket. According to such a configuration, the occurrence of rust can be further suppressed with a simple configuration.

[0046] (Technique 3) The battery according to Technique 1 or 2, wherein the tapered surface is formed by the surface of the base material without a plating layer provided thereon and is in contact with and covered by the gasket. A battery can having such a configuration may be easily manufactured, which is advantageous in the manufacturing process of a battery capable of suppressing the occurrence of rust.

[0047] (Technical 4) The battery according to Technical 3, wherein the tapered surface is the end face. With such a configuration, the occurrence of rust can be suppressed more effectively with a simple structure. Furthermore, a battery case having such a configuration can be easily manufactured, which is advantageous in the manufacturing process of a battery that can suppress the occurrence of rust.

[0048] The technology disclosed herein is useful for batteries using metal containers.

Claims

1. A battery comprising: a battery can including a bottom, a cylindrical body extending from the bottom, and an opening continuing from the body; a group of electrodes housed in the battery can; and a sealing body attached to the opening of the battery can to seal the battery can, wherein the sealing body includes a lid and a gasket disposed between the lid and the opening; the opening includes an end face having an open edge of the battery can, the end face is formed by the surface of a base material without a plating layer, the inner circumferential surface of the opening includes a tapered surface inclined with respect to the outer circumferential surface of the opening such that the thickness of the opening decreases toward the open edge, a portion of the opening bites into the gasket, and the entire surface of the end face abuts against and covers the gasket.

2. The battery according to claim 1, wherein the entire end face and a portion of the outer peripheral surface are in contact with and covered by the gasket.

3. The battery according to claim 1, wherein the tapered surface is formed by the surface of the base material which does not have a plating layer, and is in contact with and covering the gasket.

4. The battery according to claim 3, wherein the tapered surface is the end face.

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