JP4622271B2 - battery - Google Patents

Description

  The present invention relates to a battery provided with a safety valve that vents gas when the internal pressure of the battery is abnormally increased by closing a through hole formed in a metal battery container with a burst valve made of metal foil or the like.

  In many cases, a battery is configured as a sealed battery container by, for example, closing and sealing an opening of a metal battery can that houses a power generation element with a metal lid plate. Such a battery includes a battery provided with a safety valve on a cover plate of the battery container so that gas is vented when the pressure in the battery container increases abnormally (see, for example, Patent Document 1). .

  FIG. 5 shows a conventional configuration example when the safety valve is provided on the lid plate. The safety valve is formed with a recess 1a in the lid plate 1 and a through hole 1c in the center of the bottom surface 1b of the recess 1a. In the recess 1a, a rupture valve 2 made of a flat metal foil, and a metal plate An annular plate 3 having an opening at the center thereof is placed in an overlapping manner, and the rupture valve 2 and the annular plate 3 are joined to the bottom surface 1b of the recess 1a by laser welding.

However, the rupture valve 2 is a metal foil having a thickness of about several tens of μm formed with a groove 2a that is ruptured at a predetermined pressure or higher, so that the flat foil is distorted in the process of forming the groove 2a. And warping often occur. For this reason, conventionally, even if the rupture valve 2 is pressed against the bottom surface 1b of the recess 1a with the annular plate 3, a slightly raised portion is generated around the through hole 1c. Has become insufficient, and there has been a problem that liquid leakage may occur due to poor sealing during production or use. In addition, since the rupture valve 2 is formed by forming a groove 2a on a thin metal foil, an inadvertent force is applied during assembly work, causing distortion or warping, and the annular plate 3 is pressed against the bottom surface 1b of the recess 1a. In other words, if the distortion or warpage is forcibly corrected, there is a problem that a crack is generated in the groove 2a and liquid leakage may occur in the groove 2a. Furthermore, since this rupture valve 2 is a thin flat metal foil, it may be caught at the side surface when inserted into the recess 1a, and may be inserted obliquely without completely riding on the bottom surface 1b. If the annular plate 3 is further stacked and pressed in the state, the edge of the burst valve 2 may be bent or bent, which may result in insufficient joining by laser welding, which may cause liquid leakage. There was also a problem.
Japanese Patent No. 3003511

  The present invention seeks to solve the problem of forming a standing wall portion at the peripheral edge of a metal rupture valve, resulting in insufficient joining of the metal rupture valve and the risk of liquid leakage.

The invention according to claim 1 is a recess formed in the surface of the metal battery container, and a through hole is formed in a part of the bottom surface of the recess, and the bottom surface is closed so as to close the through hole in the recess. A metal burst valve disposed in the recess and a metal annular body disposed to hold the metal burst valve in the recess, and the bottom surface of the recess, the metal burst valve, and the metal annular body pass through. In the battery joined by welding around the hole, a standing wall portion along the side surface of the concave portion is formed at the peripheral edge portion of the metal burst valve.

  According to the first aspect of the present invention, since the standing wall portion is formed at the peripheral edge portion of the metal burst valve, distortion and warpage are hardly generated in the process of forming the groove. In addition, since such a standing wall portion is formed, even if an inadvertent force is applied during the assembly operation, there is no possibility of distortion or warping, and there is no possibility that the groove is easily cracked. Further, when the metal burst valve is disposed on the bottom surface, the standing wall portion extends along the side surface of the recess, so that the metal burst valve is not inserted obliquely into the recess during assembly. Accordingly, since the metal burst valve is reliably disposed between the bottom surface of the recess and the metal annular body, the joining may be insufficient, the groove may crack, and liquid leakage may occur. Nothing will happen.

  Hereinafter, the best embodiment of the present invention will be described with reference to FIGS. 1 to 4, the same reference numerals are given to the constituent members having the same functions as those of the conventional example shown in FIG.

  In the present embodiment, a nonaqueous electrolyte secondary battery in which a safety valve is provided on a lid plate will be described. As shown in FIG. 2, this non-aqueous electrolyte secondary battery has a battery container sealed by fitting a stainless steel lid plate 1 into an upper end opening of a stainless steel battery can 4 and sealing the inside by welding. It is composed. A power generation element 5 is housed inside the battery can 4.

  As shown in FIG. 1, the cover plate 1 is formed with a recess 1a that is recessed from the top surface to the inside, and a through hole 1c that leads to the inside is formed at the center of the bottom surface 1b of the recess 1a. Has been. In addition, the recessed part 1a and the through-hole 1c show here the case where it is set as the circular hollow and hole.

  On the bottom surface 1b of the recess 1a of the lid plate 1, a rupture valve 2 is disposed so as to close the through hole 1c. The rupture valve 2 is formed by forming a groove 2a having a depth of 30 μm in a cross shape in the center of a disk-shaped nickel foil having a thickness of 50 μm and forming a standing wall 2b on the entire periphery of the peripheral edge. The standing wall portion 2b is a portion where the peripheral edge portion of the horizontal disk portion 2c is bent upward in a short cylindrical shape over the entire circumference, and the outer diameter is slightly smaller than the inner diameter of the concave portion 1a. Along the side. Such a rupture valve 2 is formed by, for example, punching a nickel foil having a thickness of 20 μm into a disk shape having a standing wall portion 2b by press working, and nickel plating having a thickness of 30 μm on the upper surface of the disk portion 2c excluding the groove 2a. It is produced by giving. Accordingly, the plate thickness at the groove 2a is exactly 20 μm which is exactly the same as the thickness of the original nickel foil, so that the groove 2a can be reliably broken at a predetermined pressure or higher.

  An annular plate 3 is disposed on the rupture valve 2. The annular plate 3 is an annular stainless steel plate. The annular plate 3 is arranged on the upper surface of the disc portion 2c inside the standing wall portion 2b by making the outer diameter smaller than the inner diameter of the standing wall portion 2b of the rupture valve 2. The plate thickness of the annular plate 3 is sufficiently thicker than that of the rupture valve 2. The hole diameter of the annular plate 3 is usually larger than the through hole 1c in order to smoothly discharge the gas.

  The rupture valve 2 and the annular plate 3 arranged so as to overlap the bottom surface 1b of the recess 1a as described above are joined to the bottom surface 1b by laser welding. That is, by irradiating laser light from above the annular plate 3, the stainless steel of the annular plate 3, the nickel foil of the rupture valve 2, and the stainless steel of the lid plate 1 near the bottom surface 1b are fused and integrated. To do. Further, since the joining by laser welding is performed over the entire circumference of the through hole 1c, the through hole 1c is completely covered and sealed by the rupture valve 2. The annular plate 3 is arranged as a pressing plate to prevent the rupture valve 2 made of a thin nickel foil from being broken by the heat of laser welding and to ensure that the rupture valve 2 is welded to the bottom surface 1b. ing. The rupture valve 2 and the annular plate 3 are preliminarily fixed by resistance welding over several places around the through hole 1c in advance, so that the adhesion at the time of laser welding is improved and the joining is reliably performed. It is preferable to make it.

  In the non-aqueous electrolyte secondary battery having the above-described configuration, the battery internal pressure inside the battery container composed of the cover plate 1 and the battery can 4 is applied to the lower surface of the rupture valve 2 through the through hole 1c. When the internal pressure of the battery is abnormally increased due to, for example, heat generation due to an external short circuit and exceeds a predetermined value, the groove 2a of the rupture valve 2 is broken to discharge the high-pressure gas to the outside. Can be prevented.

  Further, the burst valve 2 having the above-described configuration is not a simple disc shape, and the standing wall portion 2b is formed at the peripheral portion, so that the disc portion 2c is surely flat when punched by press working. If this is done, the standing wall 2b may act as a rib, and distortion or warping may occur during the subsequent process of forming the groove 2a, handling during assembly work, or temporary fixing by resistance welding. Disappear. Therefore, the rupture valve 2 is disposed in close contact with the flat bottom surface 1b of the recess 1a of the cover plate 1 and is sufficiently pressed down by the flat annular plate 3 so that it can be reliably joined. become. In addition, since the burst valve 2 does not cause distortion or warpage in the disc portion 2c, the distortion or warpage is not forcibly corrected at the time of resistance welding or laser welding, and the groove 2a is not cracked. Further, since the rupture valve 2 is smoothly inserted along the side surface of the concave portion 1a, the rupture valve 2 is less likely to be caught on the side surface. Since the upper end of 2b protrudes from the recessed part 1a, it becomes easy to find before performing resistance welding or laser welding. Therefore, the burst valve 2 is inserted into the recess 1a at an angle, so that joining by laser welding is not insufficient.

  In the above embodiment, the case where the standing wall portion 2b is formed on the entire periphery of the peripheral portion of the disc portion 2c of the rupture valve 2 is shown. However, the standing wall portion 2b is formed on a part of the peripheral portion of the disc portion 2c. The same effect can be obtained even if is formed. That is, for example, as shown in FIG. 3, a plurality of standing wall portions 2b may be formed at intervals in the peripheral edge portion of the disc portion 2c. Moreover, although the case where the burst valve 2 made of nickel foil is used has been described in the above embodiment, any other metal burst as long as it is reliably ruptured at a predetermined pressure and has corrosion resistance against an electrolytic solution or the like. Valve 2 can be used. Furthermore, in the above-described embodiment, the rupture valve 2 provided with the cross-shaped groove 2a at the center of the disk portion 2c is shown. However, the shape of the groove 2a is arbitrary and can be reliably broken at a predetermined pressure or higher. In this case, the burst valve 2 without the groove 2a can be used.

  Moreover, in the said embodiment, although the case where the recessed part 1a, the rupture valve 2, and the annular plate 3 were circular was shown, these shapes are also arbitrary. That is, as shown in FIG. 4, the concave portion 1a, the rupture valve 2 and the annular plate 3 can be rectangular. Furthermore, since the annular plate 3 only needs to have a vent hole for venting gas when the rupture valve 2 is broken inside the peripheral edge portion, it is not necessary to form a hole having the same shape as the outer periphery. In addition, a guide plate or the like may be provided in the inner hole in order to avoid the ejection of gas directly above. Further, the annular plate 3 may be formed with a standing wall portion having the same shape as the standing wall portion 2 b at the peripheral edge so as to be fitted inside the standing wall portion 2 b of the burst valve 2. When such an upright wall portion is provided on the annular plate 3, it is possible to prevent distortion and warpage from occurring as in the case of the burst valve 2.

  Moreover, in the said embodiment, although the case where the cover plate 1, the battery can 4, and the annular plate 3 were made from stainless steel was shown, these metal materials are also arbitrary, respectively. Furthermore, although the case where the safety valve was provided in the cover plate 1 was shown in the said embodiment, since this safety valve may be provided in any place of a battery container, it can also be provided in the battery can 4. FIG. Furthermore, in the said embodiment, although the case where a battery container was comprised with the cover plate 1 and the battery can 4 was shown, the structure of this battery container is also arbitrary. Furthermore, although the said embodiment demonstrated the non-aqueous electrolyte secondary battery, if it is a battery which requires a safety valve, it can implement similarly to what kind of battery.

1 is a partial cross-sectional perspective view showing a configuration of a safety valve provided on a lid plate according to an embodiment of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a partially omitted vertical cross-sectional front view showing a structure of a nonaqueous electrolyte secondary battery provided with a safety valve according to an embodiment of the present invention. FIG. 10 is a perspective view showing another embodiment of the present invention and showing another configuration example of the rupture valve. FIG. 5 is a partial cross-sectional perspective view showing another embodiment of the present invention and showing another configuration example of the safety valve provided on the cover plate. It is a fragmentary sectional perspective view which shows a prior art example and shows the structure of the safety valve provided in the cover plate.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Lid board 1a Recessed part 1b Bottom face 1c Through-hole 2 Rupture valve 2b Standing wall part 3 Annular board

Claims (1)

A metal rupture formed on the surface of the metal battery container, wherein a through-hole is formed in a part of the bottom surface of the recess, and the through-hole is disposed in the recess to close the through-hole. A valve and a metal annular body arranged to hold the metal rupture valve in the recess, and the bottom surface of the recess, the metal rupture valve, and the metal annular body are joined by welding around the through hole. In the used battery,
A battery, wherein a standing wall portion along a side surface of the concave portion is formed at a peripheral edge portion of the metal burst valve.

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