JP7574541B2 - Double seaming structure, battery having the same, and method for manufacturing the double seaming structure - Google Patents

Description

The present invention relates to a double seaming structure, a battery having the same, and a method for manufacturing the double seaming structure.

Double seaming is known as a method for joining the can body and the can lid of a metal container. Double seaming provides an inexpensive and highly reliable seal. For example, Patent Documents 1 and 2 disclose the use of double seaming for electrical equipment cases. Patent Document 1 discloses that double seaming is performed by sandwiching an additional stretch film between the coated or laminated can body and the can lid in order to insulate the can body from the can lid. Patent Document 2 also discloses that an organic compound is applied to ensure hermeticity and insulation when double seaming the can body and the can lid formed from an aluminum plate laminated with a resin film.

JP 2002-343310 A JP 2006-320918 A

The objective of the present invention is to provide a double-sewn structure in which the two metals are insulated.

According to one aspect of the present invention, the double seaming structure includes a first metal member and a second metal member, and a first region including a first end face of the first metal member and a second region including a second end face of the second metal member are tightly sealed by double seaming. This double seaming structure further includes a resin layer that electrically insulates the first region from the second region and is in contact with the first end face or the second end face.

The present invention provides a double-sewn structure in which the two metals are insulated.

FIG. 1 is a partially cutaway perspective view showing an outline of a configuration example of a battery according to an embodiment. FIG. 2 is an end view showing an outline of a configuration example of a double seaming structure of a seaming section according to one embodiment. FIG. 3 is a flowchart showing an outline of an example of a method for manufacturing a battery according to an embodiment. FIG. 4 is a cross-sectional view showing an outline of an example of the shape of a can body and a can lid before double seaming. FIG. 5 is a schematic diagram showing an example of the configuration of a resin-coated container used in one embodiment. FIG. 6 is a diagram for explaining double seaming according to one embodiment. FIG. 7 is an end view showing an outline of a configuration example of a double seaming structure of a seaming section according to one modified example.

One embodiment will be described with reference to the drawings. This embodiment relates to a battery. In particular, the battery has a battery container in which a metal can body and a can lid are sealed with a double seaming structure, in which the can body and the can lid are insulated from each other, and the can body and the can lid each function as an electrode.

[Battery structure]
FIG. 1 is a partially cutaway perspective view that shows a schematic outline of an example of the configuration of a battery 1 according to the present embodiment. The battery 1 has a structure in which a battery section 9 is housed inside a battery container 2. The battery container 2 includes a can body 3 and a can lid 4, and the can body 3 and the can lid 4 are joined by a double seaming structure of a seaming section 5. The battery container 2 is sealed by the can body 3 and the can lid 4 that are joined by this double seaming structure. For the purpose of explanation, FIG. 1 shows the can body 3 and the can lid 4 of the battery container 2 cut vertically, excluding the battery section 9 inside the battery container 2 and the bottom part 31 of the can body 3.

The can body 3 has a cylindrical shape with a bottom that is open at the top. The bottom of the can body 3 is referred to as a bottom portion 31, and the side of the can body 3 is referred to as a cylindrical portion 32. The open top of the can body 3 is closed by a can lid 4. The can lid 4 is a member that closes the opening of the can body 3, and has a flat portion 41 parallel to the bottom portion 31, and a joint portion 42 that is in close contact with the cylindrical portion 32 of the can body 3.
The bottom surface portion 31 and the flat surface portion 41 may have a shape (such as a bead, not shown) for improving resistance (rigidity) against deformation due to internal pressure.

A battery unit 9 is housed in the sealed internal space of the battery container 2. The battery unit 9 may be any type of battery. For example, the battery unit 9 may be a lithium ion battery. The positive electrode of the battery unit 9 is electrically connected to the can body 3, and the negative electrode is electrically connected to the can lid 4. In this embodiment, the can body 3 and the can lid 4 are insulated by the seaming section 5. Therefore, the can body 3 functions as the positive electrode, and the can lid 4 functions as the negative electrode. The positive and negative electrodes may be reversed, with the negative electrode of the battery unit 9 connected to the can body and the positive electrode of the battery unit 9 connected to the can lid.

The size of the battery 1 is not limited to this, but may be, for example, about 70 mm in diameter and about 70 mm in height. Although not limited to this, the plate thickness of the can body 3 may be, for example, about 0.2 mm, and the plate thickness of the can lid 4 may be, for example, about 0.25 mm. In addition, the battery container 2 has, although not limited to this, a pressure resistance of, for example, about 1 MPa.

When the batteries 1 are stacked, the can body 3 of the upper battery 1 fits inside the joint 42 that rises around the flat surface 41 of the can lid 4 of the lower battery 1. At this time, the flat surface 41 of the can lid 4 of the lower battery 1 comes into contact with the bottom surface 31 of the can body 3 of the upper battery 1. Since the can body 3 and the can lid 4 are the positive and negative electrodes, respectively, stacking the batteries 1 results in the batteries 1 being connected in series.

The material of the can body 3 and the can lid 4 is preferably a metal suitable for use as an electrode. The same metal or different metals may be used for the can body 3 and the can lid 4. For example, nickel-plated steel, tin-plated steel, tin-free steel, aluminum, etc. may be used.

[Double seaming structure]
2 is an end view showing an outline of the double seaming structure 100 of the seaming section 5 according to the present embodiment. The double seaming structure 100 is formed by a first metal member 111 forming the can body 3 and a second metal member 121 forming the can lid 4. The double seaming structure 100 of the present embodiment is basically the same structure as that generally known as a double seaming structure. That is, it is formed by wrapping the curled portion of the can lid 4 around the flange portion of the can body 3 and crimping and joining them, and has a structure in which the second metal member 121 of the can lid 4 and the first metal member 111 of the can body 3 are doubled.

As shown in FIG. 2, the first metal member 111 of the can body 3 is connected to the cylindrical portion 32 and extends upward, and is folded back from its upper end to form a body hook 171 that extends downward. The total length of the body hook 171 and the body wall 172 is, but is not limited to, about 5 to 10 mm.

The second metal member 121 of the can lid 4 has a cover hook 173 that is provided between the body hook 171 and the body wall 172 so as to enter from below, a seaming wall 174 that is folded back from the lower end of the cover hook 173 to extend upward outside the body hook 171, and a chuck wall 175 that is folded back from the upper end of the seaming wall 174 to extend downward inside the body wall 172, and the chuck wall 175 is connected to the flat portion 41 of the can lid 4.

In this embodiment, the double seaming structure 100 keeps the first region 115 including the first end surface 114 of the first metal member 111 and the second region 125 including the second end surface 124 of the second metal member 121 in close contact and sealed. In order to ensure electrical insulation between the first metal member 111 and the second metal member 121, the first region 115 of the first metal member 111 is provided with a first insulating layer 131, which is a coating formed by applying an insulating paint. Similarly, the second region 125 of the second metal member 121 is provided with a second insulating layer 141, which is a coating formed by applying an insulating paint.

To ensure insulation, in this embodiment, the first insulating layer 131 is formed in the first region 115, including the first end face 114 of the first metal member 111. Similarly, the second insulating layer 141 is formed in the second region 125, including the second end face 124 of the second metal member 121. The first region 115 as the coating region is a region that is in contact with at least the second metal member 121. The second region 125 as the coating region is a region that is in contact with at least the first metal member 111.

The first insulating layer 131 and the second insulating layer 141 are formed of the same material. That is, the first insulating layer 131 and the second insulating layer 141 are formed of one type of resin composition. For example, the first insulating layer 131 and the second insulating layer 141 are formed using a silicone resin. Thus, in this embodiment, the insulating layer is a resin layer.

The thickness of the first insulating layer 131 and the second insulating layer 141 is preferably, but not limited to, 0.1 μm or more and 25 μm or less. The insulating layer can be made thin by forming the insulating layer by coating.
It should be noted that the first insulating layer 131 and the second insulating layer 141 are not limited to being formed directly on the metal member, but may be formed on the metal member after surface processing such as painting or printing has been performed.

In addition, in the double seaming structure 100 according to this embodiment, the gap between the first region 115 and the second region 125 may be filled with a sealing compound 161. This sealing compound 161 improves the sealing ability of the double seaming structure 100.

[Battery manufacturing method]
A method for manufacturing the battery 1 will now be described. Fig. 3 is a flow chart showing an outline of the method for manufacturing the battery according to this embodiment. First, the can body 3 is formed (step S1), and the can lid 4 is formed (step S2).

Figure 4 is a vertical cross-sectional view showing the outline of the shape of the can body 3 and the can lid 4 before double seaming. For the can body 3, as shown in Figure 4(b), a cup-shaped member having a bottom surface portion 31 and a cylindrical portion 32 is formed. A flange portion 38 that spreads outward is formed at the upper end portion of the cylindrical portion 32. For the can lid 4, as shown in Figure 4(a), a curl portion 48 is formed on the peripheral portion of the disk-shaped flat portion 41 so as to cover the flange portion 38 of the can body 3.

Once the can body 3 and the can lid 4 are molded, resin is applied to an area including at least the end faces of each (step S3). That is, the resin material is applied to the first area 115 including the first end face 114 of the can body 3. Similarly, the resin material is applied to the second area 125 including the second end face 124 of the second metal member 121 of the can lid 4. The first area 115 and the second area 125 may be provided corresponding to the area where the first metal member 111 and the second metal member 121 contact each other, or may be provided wider than the area of contact.

In this embodiment, the resin material is applied by, for example, immersing the first region 115 and the second region 125 in liquid resin. FIG. 5 shows an outline of a configuration example of a resin coating container 300 used in this embodiment. The resin coating container 300 has a container body 310 in a ring shape corresponding to the diameter of the flange portion 38 of the can body 3 and the curl portion 48 of the can lid 4. A groove 320 is provided in a ring shape on the upper surface of the container body 310. Liquid resin 360 is stored in this groove 320. The first region 115 of the can body 3 is immersed in the resin 360 in the groove 320 with the flange portion 38 where the first region 115 is located facing down. Similarly, the second region 125 of the can lid 4 is immersed in the resin 360 in the groove 320 with the curl portion 48 where the second region 125 is located facing down. The film thickness can be adjusted by adjusting the viscosity of the resin.

In this embodiment, the resin is an epoxy resin or a silicone resin. Epoxy resin has excellent adhesiveness and insulating properties. Silicone resin also has excellent adhesiveness and insulating properties. Furthermore, silicone resin becomes a rubber elastic body after curing and has higher toughness than epoxy resin, etc., and maintains its function as an insulating film without peeling off from the metal member even if the metal member is significantly deformed during seaming. For this reason, silicone resin is more preferable as the insulating layer of the double seaming structure 100. Instead of epoxy resin or silicone resin, urethane resin, phenolic resin, polyethylene, polypropylene, etc. may be used.

For example, Momentive Performance Materials' TSE series is a well-known silicone resin. With the TSE series, the tack-free time is about 10 to 90 minutes, and it takes about 7 days for the resin to fully harden. However, there is no need to wait until the resin has fully hardened before carrying out subsequent processing such as seaming; the next processing can be carried out once the resin has hardened appropriately.

In addition, the TSE series is expected to have an elongation rate of 140 to 300% after curing. This value is extremely large compared to the 3 to 6% elongation rate expected for epoxy. Such elongation characteristics contribute to maintaining its function as an insulating film by adhering to the metal member even when the metal member deforms during seaming. In addition, the TSE series has a dielectric breakdown voltage of 20 to 22 kV/mm, which is higher than the dielectric breakdown voltage of epoxy, 14.9 kV/mm. Therefore, silicone resin also has excellent insulating properties.

The resin application is not limited to the dipping method in which the resin is immersed in liquid resin as described above, but may be performed, for example, by application using a roller, spray application, electrostatic application, or application using a brush.

Following application of the resin, the applied resin is cured (step S4). The resin cures, for example, at room temperature, but is not limited thereto. As the resin cures, a coating that will become the first insulating layer 131 is formed in the first region 115, and a coating that will become the second insulating layer 141 is formed in the second region 125. Since the insulating layer is formed after the flange portion 38 of the can body 3 and the curled portion 48 of the can lid 4 are formed, the amount of processing of the insulating layer is smaller than when a coating of the insulating layer is formed before molding, and the insulating layer is less likely to break.

A sealing compound may be applied to the inside of the curled portion 48 of the can lid 4, which is the area that is rolled up inside the double seaming structure 100 (step S5).
Next, a separately prepared battery unit 9 is placed inside the can body 3, and the can lid 4 is placed over the opening of the can body 3 (step S6). At this time, the positive electrode of the battery unit 9 is connected to the can body 3, and the negative electrode of the battery unit 9 is connected to the can lid 4.

Finally, the flange portion 38 of the can body 3 and the curled portion 48 of the can lid 4 are seamed (step S7). The seaming of this embodiment will be described with reference to FIG. 6. FIG. 6 is a diagram for explaining the double seaming of this embodiment. As shown in FIG. 6(a), the curled portion 48 of the can lid 4 is placed on the flange portion 38 of the can body 3 during seaming. Then, as shown in FIG. 6(b), the seaming chuck 410 is fitted to the can lid 4. Next, as shown in FIG. 6(c) and (d) in order, a first seaming is performed using the first seaming roll 420, and the first metal member 111 of the can body 3 and the second metal member 121 of the can lid 4 are rolled up. Then, as shown in FIG. 6(e) and (f) in order, a second seaming is performed using the second seaming roll 430, and the first region 115 of the first metal member 111 and the second region 125 of the second metal member 121 are firmly crimped together to form a double seaming structure 100.
In this manner, the battery 1 is manufactured.

[Regarding the double seaming structure of this embodiment]
The double seaming structure 100 according to this embodiment will be further described. In the double seaming structure 100 according to this embodiment, the first metal member 111 and the second metal member 121 are well electrically insulated from each other. Therefore, the battery container 2 having the double seaming structure 100 according to this embodiment is suitable as a battery container.

By forming the insulating layer with one type of coating film, such as the first insulating layer 131 on the first metal member 111 and the second insulating layer 141 on the second metal member 121, the insulating layer can be formed cheaply and simply in one process. In addition, even if the insulating layer is formed with a single resin film without providing a coating film, the insulating layer can be formed cheaply and simply compared to providing both the coating film and the film using different materials.

In this embodiment, the first insulating layer 131 is formed up to the first end surface 114 of the first metal member 111, and the second insulating layer 141 is formed up to the second end surface 124 of the second metal member 121. With this configuration, during seaming, the first insulating layer 131 of the first end surface 114 prevents the second insulating layer 141 of the second metal member 121 from being destroyed, and the second insulating layer 141 of the second end surface 124 prevents the first insulating layer 131 of the first metal member 111 from being destroyed. Therefore, the electrical insulation between the first metal member 111 and the second metal member 121 is well maintained.

If an insulating layer were not formed on the first end surface 114 of the first metal member 111 and the second end surface 124 of the second metal member 121, the exposed first metal member 111 on the first end surface 114 would destroy the second insulating layer 141, and the exposed second metal member 121 on the second end surface 124 would destroy the first insulating layer 131. For example, this situation may occur when an insulating layer is coated or laminated onto a plate-shaped metal member and then the plate-shaped metal member is punched out to produce a molding precursor (blank).

In addition, organic compounds containing styrene butadiene rubber, ethylene propylene rubber, polyisoprene rubber, polyamide resins, polyolefin resins, etc., which are commonly used to improve the sealing performance of double seaming, have lower strength than coatings using silicone resins, etc. For this reason, commonly used organic compounds do not provide sufficient protection for the end faces of metal components, which may expose the end faces of the metal components during seaming, and the exposed metal components may destroy the insulating layer.

[First Modification]
A modified example of the above-mentioned embodiment will be described. Here, the differences from the above-mentioned embodiment will be described, and the same parts will be given the same reference numerals and their description will be omitted. Figure 7 is an end view showing the outline of the double seaming structure 101 according to this modified example.

In this double seaming structure 101, the first insulating layer 131 provided on the first metal member 111 to ensure insulation is thicker at the first end face 114 than at other parts, and a first reservoir portion 181 is formed by the resin composition. In other words, the thickness of the first insulating layer 131 on the tip side of the first end face 114 is thicker than the thickness of the first insulating layer 131 on the rear side of the first end face 114. Similarly, the second insulating layer 141 provided on the second metal member 121 is thicker at the second end face 124 than at other parts, and a second reservoir portion 182 is formed by the resin composition. In other words, the thickness of the second insulating layer 141 on the tip side of the second end face 124 is thicker than the thickness of the second insulating layer 141 on the rear side of the second end face 124.

The first reservoir 181 and the second reservoir 182 are formed by placing the first end face 114 and the second end face 124 facing downward for an appropriate period of time after the resin is applied in step S3 until the resin hardens, so that the liquid resin accumulates in the first end face 114 and the second end face 124 due to gravity.

The first insulating layer 131 and the second insulating layer 141 are thicker at the first end face 114 and the second end face 124, which increases the effect of preventing the first end face 114 and the second end face 124 from destroying the second insulating layer 141 and the first insulating layer 131 during seaming, and the electrical insulation between the first metal member 111 and the second metal member 121 is better maintained.

In addition, the first accumulation portion 181 at the tip of the body hook 171 sandwiched between the cover hook 173 and the seaming wall 174 is bulged, and by getting caught there, the body hook 171 is less likely to slip out from between the cover hook 173 and the seaming wall 174. Similarly, the second accumulation portion 182 at the tip of the cover hook 173 sandwiched between the body hook 171 and the body wall 172 is bulged, and by getting caught there, the cover hook 173 is less likely to slip out from between the body hook 171 and the body wall 172. As a result, the strength of this double seaming structure 101 is high.

[Other Modifications]
In the above-described embodiment or its modified example, the electrical insulation between the first metal member 111 and the second metal member 121 is performed by the first insulating layer 131 and the second insulating layer 141, which are resin coatings formed on the first metal member 111 and the second metal member 121, respectively. However, the present invention is not limited to this. Either the first insulating layer 131 or the second insulating layer 141 may be used.

In addition, the insulating film is not limited to a coating film, and may be, for example, a stretched film made of resin provided between the first metal member 111 and the second metal member 121. However, stretched films are relatively expensive. For this reason, as in the above-mentioned embodiment, by forming an insulating film with a coating film, electrical insulation between the first metal member and the second metal member can be achieved inexpensively. In addition, if a stretched film is sandwiched between them, the adhesion between the first metal member 111 and the second metal member 121 will be poor, and there is a risk of poor sealing in a double seaming structure with the stretched film sandwiched between them. Since higher sealing can be obtained by forming the insulating film with a coating film, it is more preferable that the insulating film is a coating film.

In addition, in the double seaming structure 100, the part where the first region 115 and the second region 125 are in close contact may be solidified with an anaerobic adhesive. The anaerobic adhesive is mainly composed of an acrylate monomer, and begins to solidify when it comes into contact with metal ions and is blocked from air. In general, it is possible to use an anaerobic adhesive that is widely used in preventing loosening of screws and in pipe joints. If the metal ions are insufficient to solidify the anaerobic adhesive, a reaction activator can also be used in combination. This anaerobic adhesive is applied to the first region 115 or the second region 125 before the formation of the double seaming structure 100, and solidifies when the air in the double seaming structure 100 is blocked by seaming. Such an anaerobic adhesive further improves the strength and sealing of the double seaming structure 100. In addition, the liquid adhesive before solidification acts as a lubricant, contributing to stable seaming.

Although the present invention has been described above by showing preferred embodiments, it goes without saying that the present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the present invention.
In the above-described embodiment, the double seaming structure is used in a battery container as an example, but it goes without saying that this double seaming structure may also be used in other articles, not limited to batteries, to join two metal components while insulating them from each other.

LIST OF SYMBOLS 1...Battery 2...Battery container 3...Can body 31...Bottom surface portion, 32...Cylindrical portion, 38...Flange portion 4...Can lid 41...Flat portion, 42...Joint portion, 48...Curled portion 5...Sealing portion 9...Battery portion 100, 101...Double seaming structure 111...First metal member, 114...First end surface, 115...First region 121...Second metal member, 124...Second end surface, 125...Second region 131...First insulating layer, 141...Second insulating layer 161...Sealing compound 171...Body hook, 172...Body wall 173...Cover hook, 174...Seaming wall, 175...Chuck wall 300...Resin-coated container 310...Container body, 320...Groove 410...Seaming chuck 420: First winding roll, 430: Second winding roll

Claims (12)

A double seaming structure comprising a first metal member and a second metal member, in which a first region including a first end surface of the first metal member and a second region including a second end surface of the second metal member are tightly sealed by double seaming,
a resin layer that electrically insulates the first region and the second region and is in contact with the first end surface or the second end surface ;
In addition to the resin layer, a layer formed by solidifying an anaerobic adhesive containing an acrylate monomer as a main component is further provided between the first region of the first metal member and the second region of the second metal member.
Double seaming structure. The double seaming structure of claim 1, wherein the resin layer contains a silicone resin. The double seaming structure according to claim 1 or 2, wherein the thickness of the resin layer provided on the first end face or the second end face is greater than the thickness of the resin layer provided on other parts. The double seaming structure according to any one of claims 1 to 3, wherein the resin layer is formed from a single type of resin composition. The double seaming structure according to any one of claims 1 to 4, wherein the resin layer has a thickness of 0.1 μm or more and 25 μm or less. The double seaming structure according to any one of claims 1 to 5, wherein the resin layer is a coating film formed on at least the first region or the second region. The double seaming structure according to any one of claims 1 to 6,
a positive electrode material and a negative electrode material contained in a space sealed by the first metal member and the second metal member,
one of the positive electrode material and the negative electrode material is connected to the first metal member;
The other of the positive electrode material and the negative electrode material is connected to the second metal member.
battery. forming a metal can body including a flange portion;
forming a metal can end including a curled portion;
forming a resin layer by coating a coating region including at least one of a first region including the molded flange portion and its end surface and a second region including the molded curled portion and its end surface ;
Applying an anaerobic adhesive containing an acrylate monomer as a main component to at least one of the first region and the second region;
and forming a double seaming structure by seaming the first region and the second region to solidify the anaerobic adhesive, in which the first region and the second region are electrically insulated by the resin layer, and a layer formed by solidifying the anaerobic adhesive in addition to the resin layer between the first region and the second region is further provided . The formation of the resin layer includes
Immersing the application area in a liquid resin;
and solidifying the resin. The manufacturing method according to claim 8 or 9, wherein forming the resin layer includes curing the resin at room temperature. The manufacturing method according to any one of claims 8 to 10, wherein the coating area is provided at least in correspondence with the area where the can body and the can lid are in contact. The manufacturing method according to any one of claims 8 to 11, wherein the resin layer contains a silicone resin.

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