JP6688029B2 - battery - Google Patents

Description

  The present disclosure relates to batteries.

  Conventionally, a flat battery called a coin battery or the like is known. The battery generally includes an outer can, a sealing can, and a gasket. The outer can and the sealing can form a space for accommodating the electrode body and the electrolytic solution. This space is sealed by a gasket.

  In recent years, as electronic devices have become thinner, batteries used in the electronic devices have been required to be thinner. For example, Patent Document 1 discloses a thin battery having a thickness of 1 mm or less. In Patent Document 1, the sealing can is formed in a hat shape and has a peripheral portion extending parallel to the bottom surface of the outer can. A convex portion protruding toward the bottom surface of the outer can is formed on the peripheral portion of the sealing can. On the bottom surface of the outer can, a convex portion that projects toward the peripheral portion of the sealing can is also formed. When these convex portions bite into the gasket, the compressibility of the gasket is increased and the sealing performance is improved.

JP, 2000-353503, A

  By the way, in the case of a thin battery, it is preferable that the gasket disposed between the outer can and the sealing can has a small thickness. However, if the thickness of the gasket is reduced, the sealing performance of the gasket may be deteriorated and liquid leakage may occur.

  The present disclosure aims to reduce the thickness of a battery while maintaining the sealing performance of the gasket.

The battery according to the present disclosure includes an outer can, a sealing can, and a gasket. The outer can has a tubular first peripheral wall portion and a bottom portion that closes one axial end of the first peripheral wall portion. The sealing can has a cylindrical second peripheral wall portion and a top portion that seals one axial end of the second peripheral wall portion. The second peripheral wall portion is arranged on the inner periphery of the first peripheral wall portion, and one end in the axial direction projects outward from the first peripheral wall portion. The second peripheral wall portion constitutes the other end portion in the axial direction and includes a folded portion having a shape that is folded outward in the radial direction and to one end side in the axial direction. The gasket closes the gap between the outer can and the sealing can. The gasket includes a gasket exterior and a gasket bottom. The outside of the gasket is arranged between the inner peripheral surface of the first peripheral wall portion and the outer peripheral surface of the second peripheral wall portion. The gasket bottom portion is arranged between the bottom portion and the second peripheral wall portion. The gasket bottom has a minimum thickness of less than 0.15 mm. The compressibility of the portion having the minimum thickness in the gasket bottom is 30% or more and less than 50% (first configuration).

  According to the first configuration, the minimum thickness of the gasket bottom is less than 0.15 mm. That is, the thickness of the gasket is extremely small between the bottom of the outer can and the peripheral wall of the sealing can. Therefore, the battery can be thinned.

Further, according to the first configuration, the compressibility of the portion having the minimum thickness in the gasket bottom is 30% or more and less than 50% , and the gasket bottom is sufficiently compressed. Further, the outside of the gasket is arranged between the inner peripheral surface of the peripheral wall portion of the outer can and the outer peripheral surface of the peripheral wall portion of the sealing can and is pressed by these surfaces. By doing so, the hermeticity of the space formed by the outer can and the sealing can can be improved. Therefore, even if the thickness of the bottom of the gasket is reduced and the battery is made thinner, the sealing performance of the gasket can be maintained.

  At the other end of the first peripheral wall portion in the axial direction, a bent portion that bends inward in the radial direction may be formed. The second peripheral wall portion may include a small diameter portion and a large diameter portion. The small diameter portion is connected to the top portion. A part of the small diameter portion projects outward from the first peripheral wall portion. The large diameter portion is connected to the small diameter portion via a step. The large diameter portion has an outer diameter larger than the outer diameter of the small diameter portion. The minimum thickness of the gasket bottom may be 0.08 mm or more (second configuration).

  According to the second configuration, the gasket bottom portion has a thickness of 0.08 mm or more. Therefore, it is possible to prevent the gasket bottom portion from tearing due to the pressure from the peripheral wall portion of the sealing can.

  According to the present disclosure, it is possible to reduce the thickness of a battery while maintaining the sealing performance of the gasket.

FIG. 1 is a vertical sectional view of a battery according to an embodiment. FIG. 2 is a vertical cross-sectional view of the peripheral portion of the battery according to the embodiment.

  Hereinafter, embodiments will be described with reference to the drawings. The same or corresponding components in the drawings are designated by the same reference numerals, and the same description will not be repeated. For convenience of explanation, in each drawing, the configuration may be illustrated in a simplified or schematic manner, or a part of the configuration may be omitted.

[Battery structure]
FIG. 1 is a vertical cross-sectional view of a battery 10 according to the embodiment. The battery 10 is a so-called coin-shaped battery and has a substantially columnar shape. The battery 10 is a flat battery whose axial dimension is smaller than the outer diameter. The axial dimension L of the battery 10 is, for example, 1 mm or less.

  The battery 10 includes an outer can 1, a sealing can 2, a gasket 3, and an electrode body 4.

  The outer can 1 is made of a metal material such as stainless steel. The outer can 1 has a peripheral wall portion 11 and a bottom portion 12. The peripheral wall portion 11 has a tubular shape. The bottom portion 12 closes one end of the peripheral wall portion 11 in the axial direction. The bottom portion 12 has a disc shape. The other end of the peripheral wall portion 11 in the axial direction is open. Hereinafter, for convenience of description, the bottom portion 12 side may be referred to as a lower side and the opposite side may be referred to as an upper side.

  The peripheral wall portion 11 has a peripheral wall body 11a and a bent portion 11b. The peripheral wall body 11 a has a substantially cylindrical shape, and the lower end thereof is connected to the peripheral edge of the bottom portion 12. The bent portion 11b is continuous with the upper end of the peripheral wall body 11a. The bent portion 11b is bent radially inward with respect to the peripheral wall body 11a. The bent portion 11b constitutes an opening edge portion of the outer can 1.

  The axial dimension L1 of the peripheral wall portion 11 is preferably 0.70 mm or less, and more preferably 0.60 mm or less. The dimension L1 is preferably 0.50 mm or more. The dimension L1 is the axial length from the lower end of the peripheral wall body 11a (the lower surface of the bottom portion 12) to the upper end of the bent portion 11b.

  Like the outer can 1, the sealing can 2 is also made of a metallic material such as stainless steel. The sealing can 2 has a peripheral wall portion 21 and a top portion 22.

  The peripheral wall portion 21 has a tubular shape. The peripheral wall portion 21 is arranged on the inner periphery of the peripheral wall portion 11 of the outer can 1. At least a part of the outer peripheral surface of the peripheral wall portion 21 faces the inner peripheral surface of the peripheral wall portion 11 of the outer can 1 via the gasket 3. That is, the outer peripheral surface of the peripheral wall portion 21 has a portion that presses the gasket 3 together with the inner peripheral surface of the peripheral wall body 11 a of the outer can 1. In the present embodiment, the folded portion 21d included in the peripheral wall portion 21 presses the gasket 3.

  One end (upper end) in the axial direction of the peripheral wall portion 21 projects outward from the peripheral wall portion 11 of the outer can 1. That is, the upper end of the peripheral wall portion 21 projects above the upper end of the peripheral wall portion 11. The top portion 22 closes the upper end of the peripheral wall portion 21. The other end (lower end) in the axial direction of the peripheral wall portion 21 is open.

  The peripheral wall portion 21 includes a small diameter portion 21a and a large diameter portion 21b. The small diameter portion 21 a is connected to the top portion 22. The outer diameter of the large diameter portion 21b is larger than the outer diameter of the small diameter portion 21a. The large diameter portion 21b is arranged below the small diameter portion 21a, and is connected to the small diameter portion 21a via a step. In other words, the large diameter portion 21b is connected to the small diameter portion 11a by the connecting portion 21c extending radially outward from the lower end of the small diameter portion 21a.

  The upper end of the small diameter portion 21 a projects upward from the peripheral wall portion 11 of the outer can 1. Therefore, the top portion 22 is arranged above the bent portion 11b of the outer can 1. The large diameter portion 21b and the connecting portion 21c are arranged below the bent portion 11b. With such a configuration, a convex portion is formed on the upper surface of the battery 10. The axial dimension L21 of the convex portion is, for example, 0.15 to 0.40 mm. The dimension L21 is the length from the upper end of the bent portion 11b to the upper surface of the top portion 22.

  The large diameter portion 21b has a folded portion 21d. The folded-back portion 21d constitutes an opening edge portion of the sealing can 2. The folded portion 21d constitutes the lower end portion of the peripheral wall portion 21 and has a shape that is folded outward in the radial direction and toward the upper end side. The folded-back portion 21d is formed by folding the lower end of the large-diameter portion 21b radially outward and upward. In the present embodiment, the tip of the folded portion 21d reaches the same height as the upper surface of the connecting portion 21c. That is, almost the entire large diameter portion 21b is formed by the folded portion 21d. However, the tip of the folded portion 21d may be located below the connecting portion 21c. Alternatively, the tip of the folded portion 21d may be located above the connecting portion 21c.

  The gasket 3 is configured to close the gap between the outer can 1 and the sealing can 2. The gasket 3 is arranged on the peripheral wall portion 21 of the sealing can 2. The gasket 3 includes a gasket inner portion 31, a gasket outer portion 32, and a gasket bottom portion 33.

  The gasket interior 31 is arranged on the inner peripheral side of the peripheral wall portion 21 of the sealing can 2. The gasket inner part 31 covers the entire inner peripheral surface of the peripheral wall portion 21. The gasket exterior 32 is arranged on the outer peripheral side of the peripheral wall portion 21. The gasket outer portion 32 is arranged between the peripheral wall portion 21 and the peripheral wall portion 11 of the outer can 1. The gasket bottom portion 33 is a portion that connects the gasket inner portion 31 and the gasket outer portion 32. The gasket bottom portion 33 is arranged between the peripheral wall portion 21 and the bottom portion 12 of the outer can 1.

  The gasket 3 is made of a resin material. Examples of the resin material include polyphenylene sulfide (PPS), polyethylene (PE), polypropylene (PP), polyethylene terephthalate (PET), perfluoroalkoxy fluororesin (PFA), and polyether ether ketone (PEEK). .

  The electrode body 4 is housed in a space formed by the outer can 1, the sealing can 2 and the gasket 3. A nonaqueous electrolytic solution (not shown) is also stored in the space. The electrode body 4 includes a positive electrode 41, a negative electrode 42, and a separator 43.

  The positive electrode 41 is formed in a disc shape, for example. The positive electrode 41 has a positive electrode current collector 41a and a positive electrode active material layer 41b. The positive electrode collector 41a is made of a metal foil such as aluminum. The positive electrode active material layer 41b contains a positive electrode active material such as a lithium transition metal composite oxide such as lithium cobalt oxide, lithium nickel oxide, or lithium manganate. The positive electrode active material layer 41b is formed on the positive electrode current collector 41a. The positive electrode current collector 41 a contacts the inner surface of the bottom portion 12 of the outer can 1. Thereby, the outer can 1 functions as the positive electrode of the battery 10.

  The negative electrode 42 is formed in a disc shape, for example. The negative electrode 42 has a negative electrode current collector 42a and a negative electrode active material layer 42b. The negative electrode collector 42a is made of a metal foil such as copper. The negative electrode active material layer 42b contains a negative electrode active material such as graphite or lithium foil. The negative electrode active material layer 42b is formed on the negative electrode current collector 42a. The negative electrode current collector 42 a contacts the inner surface of the top portion 22 of the sealing can 2. As a result, the sealing can 2 functions as the negative electrode of the battery 10.

  The separator 43 is formed in, for example, a circular shape. The separator 43 is arranged between the positive electrode 41 and the negative electrode 42. The separator 43 is composed of a microporous thin film made of polyethylene or polypropylene.

  Hereinafter, the gasket bottom portion 33 and the gasket outer portion 32 will be described in more detail with reference to FIG. FIG. 2 is a vertical cross-sectional view of the peripheral portion of the battery 10.

  As described above, the gasket bottom 33 is arranged between the bottom 12 of the outer can 1 and the peripheral wall 21 of the sealing can 2. More specifically, the gasket bottom 33 is sandwiched between the bottom 12 of the outer can 1 and the opening edge of the peripheral wall 21 of the sealing can 2. The thickness of the gasket bottom portion 33 is the smallest between the inner surface of the bottom portion 12 and the lower end of the peripheral wall portion 21. The minimum thickness A of the gasket bottom 33 is less than 0.15 mm. The minimum thickness A of the gasket bottom 33 is preferably 0.08 mm or more.

  The gasket bottom portion 33 is compressed between the bottom portion 12 of the outer can 1 and the peripheral wall portion 21 of the sealing can 2. The gasket bottom portion 33 is pressed by the opening edges of the bottom portion 12 and the peripheral wall portion 21. The lower surface of the opening edge portion of the peripheral wall portion 21 that contacts the gasket bottom portion 33 is preferably configured by one curved surface having no protruding portion or the like. For example, the lower surface of the folded portion 21d is a circular arc surface. However, the lower surface of the folded portion 21d does not have to be a perfect arcuate surface. The lower surface of the folded portion 21d may be a distorted curved surface (curved surface that is not a circular arc) whose curvature changes. The inner surface of the bottom portion 12 is also preferably a flat surface without any protrusions or the like.

  The gasket outer portion 32 is arranged between the peripheral wall portion 11 of the outer can 1 and the peripheral wall portion 21 of the sealing can 2. The gasket outer portion 32 is sandwiched by the peripheral wall portions 11 and 21. The thickness of the portion of the gasket outer portion 32 located above the large diameter portion 21b, that is, the portion in contact with the tip of the folded portion 21d is determined in consideration of the minimum thickness A of the gasket bottom portion 33.

  The thickness of the portion of the gasket outer portion 32 that comes into contact with the tip of the folded-back portion 21d affects the pressure applied from the peripheral wall portion 21 of the sealing can 2 to the gasket bottom portion 33. Assuming that the minimum thickness of the portion of the gasket outer portion 32 that contacts the tip of the folded portion 21d is B, the ratio B / A of B to the minimum thickness A of the gasket bottom portion 33 is less than 1.5. B / A is preferably larger than 1.27. B can be, for example, 0.14 to 0.16 mm.

  The gasket outer portion 32 is compressed between the peripheral wall portion 11 of the outer can 1 and the folded portion 21d of the sealing can 2. Since the folded-back portion 21d is formed by folding the lower end portion of the large-diameter portion 21b radially outward and upward, it has an outer surface S. At least a part of the outer surface S of the folded-back portion 21d faces the inner peripheral surface of the peripheral wall body 11a of the peripheral wall portion 11 via the gasket outer portion 32. A part of the gasket outer part 32 is pressed by the outer surface S of the folded portion 21d and the inner peripheral surface of the peripheral wall body 11a. In the gasket outer portion 32, a portion mainly in contact with the outer surface S of the folded portion 21d and a portion in contact with the outer can 1 from the outer peripheral edge portion of the bottom portion 12 to a part of the peripheral wall body 11a and the bent portion 11b. And are pressed.

  The axial dimension L3 of the outer surface S of the folded-back portion 21d is preferably 0.12 mm or more from the viewpoint of more reliably pressing the gasket exterior 32. The dimension L3 is the length in the axial direction from the tip (upper end) of the folded portion 21d to the lower end of the peripheral wall portion 21. The thickness C of the portion of the gasket outer portion 32 arranged between the outer surface S of the folded portion 21d and the inner peripheral surface of the peripheral wall body 11a is preferably 0.18 to 0.23 mm.

[Battery manufacturing method]
Next, an example of a method for manufacturing the battery 10 will be described. The manufacturing method of the battery 10 includes a step of manufacturing the outer can 1, a step of manufacturing the sealing can 2, a step of attaching the gasket 3 to the peripheral wall portion 21 of the sealing can 2, and the outer can 1 and the gasket 3. And a step of assembling the sealing can 2 and the electrode body 4.

  The outer can 1 is manufactured by pressing a metal plate. The bent portion 11b is not formed in the peripheral wall portion 11 of the outer can 1 before being combined with other members. That is, at the time of finishing the press working, the peripheral wall portion 11 of the outer can 1 extends substantially straight in the axial direction over the whole.

  The sealing can 2 is also manufactured by pressing a metal plate. The sealing can 2 is formed in the shape shown in FIG.

  The gasket 3 is formed on the peripheral wall portion 21 of the sealing can 2 by insert molding, for example. Thereby, the sealing can 2 to which the gasket 3 is attached can be easily obtained. However, the gasket 3 may be attached to the peripheral wall portion 21 of the sealing can 2 after the gasket 3 that is separate from the sealing can 2 is formed. At this point, the gasket 3 is formed in a substantially U shape in a sectional view. That is, the gasket outer portion 32 does not extend along the outer peripheral surface of the peripheral wall portion 21 and extends generally in the axial direction. The upper end of the gasket outer portion 32 may protrude above the top portion 22 of the sealing can 2.

  After the gasket 3 is attached to the sealing can 2, the sealing can 2 is combined with the outer can 1 and the electrode body 4. Specifically, the electrode body 4 is placed in the outer can 1 with the bottom 12 facing downward, and the nonaqueous electrolytic solution is injected. Then, after the sealing can 2 to which the gasket 3 is attached is put over the outer can 1, the bent edge 11b is formed by caulking the opening edge portion of the peripheral wall portion 11 of the outer can 1 inward in the radial direction.

The opening edge portion of the peripheral wall portion 11 of the outer can 1 has a large diameter portion 21b and a large diameter portion 21b of the peripheral wall portion 21 of the sealing can 2 such that the compression rate of the portion having the minimum thickness A of the gasket bottom portion 33 is 30 to 50%. It is crimped to the connecting portion 21c. The compression rate can be calculated by the following equation (1).
{(Minimum thickness of gasket bottom 33 in uncompressed state-Minimum thickness A of gasket bottom 33 in compressed state) / Minimum thickness of gasket bottom 33 in non-compressed state} × 100 (1)

  In the above formula (1), the “non-compressed state” means that the gasket bottom 33 is not pressed by the bottom 12 of the outer can 1 and the peripheral wall 21 of the sealing can 2, that is, the gasket bottom before combining the members. 33 state. The “compressed state” is a state in which the gasket bottom portion 33 is sandwiched between the bottom portion 12 and the peripheral wall portion 21 by being combined with each other and is pressed by the bottom portion 12 and the peripheral wall portion 21.

  By caulking the opening edge portion of the peripheral wall portion 11 of the outer can 1, the space in which the electrode body 4 and the nonaqueous electrolytic solution are stored is sealed, and the battery 10 is completed.

[Effect of Embodiment]
In the battery 10 according to this embodiment, the minimum thickness A of the gasket bottom portion 33 is less than 0.15 mm, which is extremely small. Therefore, the battery 10 can be thinned.

Further, in the battery 10 according to the present embodiment, the compressibility of the portion having the minimum thickness A in the gasket bottom 33 is 30 to 50 %, and the gasket bottom 33 is sufficiently compressed. Thereby, the sealing performance of the gasket 3 can be improved.

  Further, in the battery 10 according to the present embodiment, a part of the gasket outer part 33 is pressed by the inner peripheral surface of the peripheral wall body 11 a of the outer can 1 and the outer surface S of the folded portion 21 of the sealing can 2. That is, the peripheral wall portion 11 of the outer can 1 and the peripheral wall portion 21 of the sealing can 2 come into surface contact with the gasket outer portion 33, so that radial pressure is reliably applied to the gasket outer portion 33. In particular, in the gasket outer portion 32, the portion in contact with the outer can 1 from the outer peripheral edge portion of the bottom portion 12 to a part of the peripheral wall body 11a and the bent portion 11b is continuously pressed, so that the sealing performance of the gasket 3 is improved. Can be increased. Thereby, the sealing property of the space in which the electrode body 4 and the non-aqueous electrolyte solution are stored is improved. Therefore, even when the thickness of the gasket bottom 33 is reduced and the battery 10 is thinned, the sealing performance of the gasket 3 can be maintained and liquid leakage can be prevented.

  In the battery 10 according to the present embodiment, the minimum thickness A of the gasket bottom portion 33 is preferably 0.08 mm or more. As a result, it is possible to prevent the gasket bottom portion 33 from tearing due to pressure from the bottom portion 12 of the outer can 1 and the peripheral wall portion 21 of the sealing can 2.

  In the battery 10 according to this embodiment, the lower surface of the folded portion 21d is preferably a smooth curved surface. The inner surface of the bottom portion 12 of the outer can 1 is also a flat surface. In this case, it is possible to prevent stress concentration from occurring in the gasket bottom portion 33 arranged between the folded portion 21d and the bottom portion 12. Therefore, tearing of the gasket bottom 33 can be suppressed.

  In the battery 10 according to this embodiment, the ratio B / A of the minimum thickness B of the upper portion of the gasket outer portion 32 to the minimum thickness A of the gasket bottom portion 33 is set to less than 1.5. That is, the thickness of the portion of the gasket outer portion 32 arranged above the gasket bottom portion 33 does not become too large with respect to the thickness of the gasket bottom portion 33. As a result, the pressure load on the gasket bottom 33 is reduced, and it is possible to prevent the gasket bottom 33 from tearing.

  In the battery 10 according to the present embodiment, the convex portion is formed on the upper surface by disposing the upper end of the peripheral wall portion 21 of the sealing can 2 above the upper end of the peripheral wall portion 11 of the outer can 1. This convex portion can be used for positioning the battery 10 with respect to the electronic device. Therefore, the battery 10 can be accurately and easily attached to the electronic device.

  In general, when the thickness of the bottom of the gasket is large, the shoulder opening after crimping the opening edge of the outer can becomes high, which may make it difficult to position the battery with respect to the electronic device. On the other hand, if a gasket with a large thickness is used and the opening edge of the outer can is caulked with a strong force to obtain a predetermined thickness, and the compressibility of the bottom of the gasket becomes high, the sealing can will be deformed as the gasket deforms The battery may be deformed, and the hermeticity of the battery may deteriorate.

  On the other hand, in the battery 10 according to the present embodiment, the gasket bottom portion 33 has a small thickness, and the compression rate thereof is set within an appropriate range. Therefore, the battery 10 can be easily positioned with respect to the electronic device, and high sealing performance can be ensured.

  Although the embodiment has been described above, the present disclosure is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the present disclosure.

  For example, in the battery according to the above embodiment, the folded portion is formed at the lower end of the peripheral wall portion of the sealing can. However, the folded back portion may not be formed at the lower end of the peripheral wall portion of the sealing can.

  The battery according to the above embodiment includes an electrode body having a single-layer electrode structure. However, the structure of the electrode body is not limited to this. For example, a pellet-shaped electrode can be used.

  In the battery according to the above embodiment, the outer can functions as a positive electrode and the sealing can functions as a negative electrode. However, the outer can can function as the negative electrode and the sealing can can function as the positive electrode. Further, the outer can and the sealing can themselves do not have to serve as the positive electrode or the negative electrode. In this case, in the battery, a terminal for contacting the terminal of the electronic device may be separately provided.

  In the above embodiment, after the gasket is attached to the sealing can, the sealing can and the outer can are combined. However, a gasket may be separately prepared, and the gasket may be fitted between the outer can and the sealing can in the final assembly stage.

  Hereinafter, the present disclosure will be described in more detail with reference to examples. However, the present disclosure is not limited to the following examples.

[About gasket sealing performance]
As Examples 1-1, 1-2, and Comparative Example 1, ten batteries each having the structure shown in FIGS. 1 and 2 were prepared. In Example 1-1, Example 1-2, and Comparative Example, the minimum thickness (A) of the gasket bottom (33) and the compressibility of the portion of the gasket bottom (33) having the minimum thickness (A) are mutually different. different.

  In each battery according to Example 1-1, the minimum thickness (A) of the gasket bottom portion (33) was 0.1 mm, and the compressibility of the portion having the minimum thickness (A) of the gasket bottom portion (33) was 50%. . In each battery according to Example 1-2, the minimum thickness (A) of the gasket bottom portion (33) was 0.13 mm, and the compressibility of the portion having the minimum thickness (A) of the gasket bottom portion (33) was 35%. . In each battery according to Comparative Example 1, the minimum thickness (A) of the gasket bottom portion (33) was 0.16 mm, and the compressibility of the portion having the minimum thickness (A) of the gasket bottom portion (33) was 20%. In all the batteries, PPS was used as the material of the gasket (3).

  A heat shock test was performed on each of the batteries according to Example 1-1, Example 1-2, and Comparative Example 1. In the test, each battery was charged at 3.8 V, held at 60 ° C. for 1 hour, and then held at −10 ° C. for 1 hour, which was repeated 120 cycles for 10 days. The said test was implemented using the heat shock test apparatus of the 2 zone movement system which moves each battery between a 60 degreeC thermostat and a -10 degreeC thermostat. For each battery, the occurrence of liquid leakage was confirmed with a microscope (20 times).

  On the sixth day of the test, liquid leakage occurred in one of the batteries according to Comparative Example 1 (leakage generation rate 10%). No leak occurred in each of the batteries according to Example 1-1 and Example 1-2 (leak rate 0%).

As described above, in Examples 1-1 and 1-2 in which the minimum thickness (A) of the gasket bottom portion (33) is less than 0.15 mm and the compressibility is in the range of 30 to 50 %, liquid leakage It has been confirmed that does not occur. Therefore, in order to make the battery thinner, the minimum thickness (A) of the gasket bottom (33) is set to less than 0.15 mm, and the compression ratio of the portion having the minimum thickness (A) in the gasket bottom (33) is 30 to 50 %. Then, it can be said that the sealing performance of the gasket (3) can be maintained.

[About gasket tearing]
A plurality of batteries having different minimum thicknesses (A) of the gasket bottom portion (33) and the minimum thickness (B) of a portion (upper portion) of the gasket outer portion (32) that contacts the tip of the folded portion (21d) were produced. The occurrence of tearing of the bottom (33) was confirmed. In all the batteries, PPS was used as the material for the gasket (3).

  As shown in Table 1, in the batteries of Examples 2-1 to 2-4 in which the minimum thickness (A) of the gasket bottom portion (33) was 0.08 mm or more, the gasket bottom portion (33) did not tear. . On the other hand, in the battery of Comparative Example 2 in which the minimum thickness (A) was less than 0.08 mm, the gasket bottom part (33) was torn. The ratio (B / A) of the minimum thickness (B) of the upper part of the gasket outer part (32) to the minimum thickness (A) of the gasket bottom part (33) was less than 1.5 in Examples 2-1 to 2-4. In Comparative Example 2, it is 1.5 or more.

  From the above, it was found that if the minimum thickness (A) of the gasket bottom portion (33) is 0.08 mm or more, tearing of the gasket bottom portion (33) is suppressed. By suppressing the tearing of the gasket bottom portion (33), the sealing performance can be maintained and a short circuit due to the contact between the outer can (1) and the sealing can (2) can be prevented.

  10: Battery, 1: Exterior can, 11: First peripheral wall part, 12: First flat plate part, 2: Sealing can, 21: Second peripheral wall part, 21a: Small diameter part, 21b: Large diameter part, Folded part: 21d , 22: second flat plate part, 3: gasket, 32: outside of gasket, 33: bottom part of gasket

Claims (3)

An outer can having a tubular first peripheral wall portion and a bottom portion that closes one axial end of the first peripheral wall portion;
The cylindrical second peripheral wall portion, which is disposed on the inner periphery of the first peripheral wall portion and has one axial end protruding outward from the first peripheral wall portion, closes the axial end of the second peripheral wall portion. A sealing can having a top,
A gasket that closes the gap between the outer can and the sealing can,
Equipped with
The second peripheral wall portion,
A folded-back portion that constitutes the other end portion in the axial direction and has a shape that is folded back radially outward and to one end side in the axial direction,
Including,
The gasket is
An outer gasket located between the inner peripheral surface of the first peripheral wall portion and the outer peripheral surface of the second peripheral wall portion,
A gasket bottom disposed between the bottom and the second peripheral wall and having a minimum thickness of less than 0.15 mm;
Including,
When the minimum thickness of the portion of the gasket outside the gasket that comes into contact with the tip of the folded portion of the sealing can is B, the ratio B / A to the minimum thickness A of the gasket bottom is 1.2 or more and less than 1.5,
A battery having a compression ratio of 30% or more and less than 50% in a portion having a minimum thickness in the gasket bottom portion. The battery according to claim 1, wherein
At the other end of the first peripheral wall portion in the axial direction, a bent portion that bends inward in the radial direction is formed,
The second peripheral wall portion,
A small-diameter portion connected to the top portion, a part of which projects outward from the first peripheral wall portion;
A large-diameter portion connected to the small-diameter portion via a step, and having a larger outer diameter than the outer diameter of the small-diameter portion;
Including,
The minimum thickness of the bottom of the gasket is 0.08 mm or more. The battery according to claim 1 or 2, wherein
The resin material forming the gasket is polyphenylene sulfide (PPS), polyethylene (PE), polypropylene (PP), polyethylene terephthalate (PET), perfluoroalkoxy fluororesin (PFA), or polyether ether ketone (PEEK). ,battery.

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