JP6096504B2 - Battery with pressure relief valve - Google Patents

Description

  The present invention relates to a battery with a pressure relief valve in which a holder for holding a pressure relief valve is attached to a part of a lid.

A lithium ion battery is known in which a through-hole is provided in a part of a lid of a battery case including a battery case and a lid, and a holder for holding a pressure relief valve is attached to the through-hole (for example, Patent Documents 1 and 2). Conventionally, there is a type using a rupture disk for this pressure release valve. The rupture disk is made of a metal film having a thickness of 0.1 mm or less, and has a structure in which the pressure is released to the outside of the battery by rupturing when the internal pressure of the battery rises.
Therefore, in order to prevent damage during handling of the rupture disc, the disc holder that holds the rupture disc includes a metal upper holder that welds the rupture disc and a metal lower holder that surrounds the rupture disc. And having an upper holder and a lower holder joined by welding or the like.

Japanese Patent Laid-Open No. 10-334883 Japanese Patent No. 3727225

However, in the conventional configuration, the structure around the pressure release valve is large, so that depending on the size of the battery, the metal disk holder and the positive and negative terminals arranged in the vicinity may come into contact with each other, causing an internal short circuit. There is.
In addition, it is necessary to join a large number of parts constituting a disc holder that holds the rupture disc by welding or the like, and there are many joining points, and the assembly work is complicated.
The present invention has been made in view of the above-described circumstances, and an object thereof is to provide a battery with a pressure relief valve capable of preventing internal short circuit and improving assembly while reducing damage to the pressure relief valve. To do.

In order to achieve the above object, the present invention provides a through-hole in the lid of a battery case having a bottomed battery case with one end opened and a lid that closes the opening of the battery case. In a battery with a pressure release valve to which a disk holder for holding a pressure release valve is attached, the lid is insulated from an electrode terminal of the battery, the lid is insulated from an electrode terminal of the battery, and the disk holder is A metal first holder to which a pressure release valve is welded and attached to the through hole, and a second holder that fits on an outer peripheral surface of the first holder to protect the pressure release valve and have electrical insulation. It is characterized by.
In addition, the present invention provides a disc in which a through hole is provided in the lid of a battery case having a bottomed battery case having one end opened and a lid that closes the opening of the battery case, and a pressure relief valve is held in the through hole. In the battery with a pressure relief valve to which a holder is attached, the disk holder is fitted with a metal first holder to which the pressure relief valve is welded and attached to the through hole, and an outer peripheral surface of the first holder, and the pressure relief valve. And a second holder having electrical insulation, wherein the second holder covers all outer peripheral surfaces of the first holder that are exposed in the battery case.
According to this configuration, since the second holder having electrical insulation is fitted to the metal first holder attached to the through hole of the battery case by welding the pressure release valve, the pressure release valve is protected. While reducing damage, it is possible to prevent internal short circuit and improve assembly.

The said structure WHEREIN: The said 2nd holder may cover the whole outer periphery exposed in the said battery case in the said 1st holder. According to this configuration, an internal short circuit can be more effectively prevented.
Further, in the above configuration, the second holder integrally includes a cylindrical portion that covers an outer peripheral surface exposed in the battery case in the first holder and a cover portion that covers an outer peripheral edge of the pressure release valve, At the time of fitting, the cover part may be in contact with the first holder and the cylindrical part may be positioned at a position covering the entire outer peripheral surface of the first holder. According to this configuration, the mounting position of the second holder can be easily set to an appropriate position.

In the above configuration, the second holder may be made of resin. According to this structure, it can reduce in weight compared with the case where it makes it metal.
In the above configuration, the pressure release valve may be a rupture disk. According to this configuration, with a configuration using a rupture disk having a structure that is easily ruptured, damage to the rupture disk can be reduced while preventing internal short circuit and improving assembly.
In the above configuration, the battery may be a lithium ion secondary battery. According to this structure, the lithium ion secondary battery which can prevent an internal short circuit more effectively can be provided.

  According to the present invention, it is possible to prevent internal short circuit and improve assembly while reducing damage to the pressure release valve.

It is a figure which shows the pressure release valve structure of the lithium ion battery which concerns on embodiment of this invention. It is the figure which looked at the lithium ion battery from the upper part. It is the figure which showed the pressure release valve unit. It is an exploded view of a pressure release valve unit. It is a figure which shows the 1st process required for the assembly of a pressure release valve unit. It is a figure which shows the 2nd process required for the assembly of a pressure release valve unit. It is the figure which showed the comparative example.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 shows a pressure relief valve structure of a lithium ion battery 10 according to an embodiment of the present invention. In FIG. 1, the left region shows the internal structure and the right region shows the external appearance with respect to the central axis C1 penetrating the lithium ion battery 10 vertically. Moreover, FIG. 2 has shown the figure which looked at the lithium ion battery 10 from upper direction.
The lithium ion battery 10 includes a power generation element 12 such as a positive and negative electrode, a separator, and an electrolytic solution disposed in a battery case 11 having a bottomed housing having an opening 11A having an upper surface opened as one end. The opening 11 </ b> A of the tank 11 is formed by closing with a lid (lid) 13. The battery case 11 and the lid 13 are joined to each other by a joining method such as laser welding so as to maintain airtightness, thereby forming a battery case 15 having an airtight structure. In FIG. 1, reference numeral 16 indicates a reinforcing body made of a synthetic resin such as polypropylene that reinforces the battery case 15 disposed on the power generation element 12.

The battery case 11 and the lid 13 constituting the battery case 15 are made of metal in order to ensure strength. In the present embodiment, the battery case 11 and the lid 13 are made of an aluminum alloy that achieves both strength and weight reduction. Moreover, although the lithium ion battery 10 of this embodiment has shown the case where the battery case 15 is a square battery formed in a square, it is not limited to a square, and other shapes such as a cylinder may be applied.
A pair of electrode terminals (positive electrode terminal, negative electrode terminal) 17 and 18 are attached to the lid body 13 so as to penetrate therethrough, and between the pair of electrode terminals 17 and 18, a single piece that penetrates in the thickness direction of the lid body 13. One through hole 19 is formed. A pressure relief valve unit 21 is attached to the through hole 19 from the inside of the lid 13.
In FIG. 1, reference numerals 17p and 18n are sealing portions formed between the electrode terminals 17 and 18 and the lid 13 through which the electrode terminals 17 and 18 pass, and are formed so as to surround the electrode terminals 17 and 18. 18 and the lid 13 are insulated and hermetically sealed.
Further, although not shown, the positive and negative electrodes in the power generation element 12 are electrically connected to the electrode terminals 17 and 18 by conductors that penetrate the reinforcing body 16, respectively.

FIG. 3 is a view showing the pressure release valve unit 21, with respect to the central axis C <b> 1, the left region shows the internal structure and the right region shows the appearance.
The pressure relief valve unit 21 includes a rupture disc 22 that constitutes a pressure relief valve, and a disc holder 24 that holds the rupture disc 22.
The rupture disk 22 is a thin metal plate that is ruptured and released at a predetermined set pressure, and is also referred to as a rupture disk. In this embodiment, an Ω-shaped (dome-shaped) rupture disk is used, but a pressure relief valve other than a dome-shaped valve such as an inverted type may be used as long as desired performance is ensured.

As shown in FIG. 3, the disc holder 24 includes an upper holder (first holder) 31 joined to the lid 13 by welding and a lower holder that surrounds and protects the rupture disc 22 between the upper holder 31. (Second holder) 32. By employing the disk holder 24 having this configuration, the following effects can be obtained.
1) Since the thin film rupture disk 22 is easily damaged by a slight stress, the rupture disk 22 can be prevented from being accidentally damaged by providing a disk holder 24 having a shape covering the periphery.
2) Rather than welding the thin rupture disk 22 directly to the battery case 15, the work of welding the rupture disk 22 to the disk holder 24 separate from the battery case 15 and then welding to the battery case 15 is better. Therefore, weldability and airtightness can be easily secured, and the defect rate is reduced, which is advantageous for cost reduction.
3) In addition to 2), since the battery case 15 is generally expensive among battery components, the probability of damaging the battery case 15 due to poor welding can be reduced, which also reduces the defect rate and reduces costs. Is advantageous.

A detailed configuration of the disc holder 24 will be described.
FIG. 4 shows an exploded view of the pressure relief valve unit 21.
The upper holder 31 of the disc holder 24 is formed as a perfect circular cylindrical member that can be welded to the through hole 19 provided in the lid body 13. More specifically, the outer holder 31 has the same diameter as the through hole 19. A small-diameter cylindrical portion 34 formed on the surface 34G and a large-diameter cylindrical portion 35 having an outer peripheral surface 35G larger in diameter than the small-diameter cylindrical portion 34 are integrally provided on the coaxial line, and are formed of a metal material such as an aluminum alloy. ing.
As shown in FIGS. 1 and 2, the small-diameter cylindrical portion 34 is inserted into the through hole 19 provided in the lid body 13 from below, and the periphery of the upper end portion is joined to the lid body 13 without a gap by welding. Thus, it functions as a lid joint portion joined to the lid body 13.

The large-diameter cylinder portion 35 has substantially the same diameter as the outer diameter of the rupture disc 22, and the outer peripheral portion of the rupture disc 22 is joined to a surface (lower surface) 35 </ b> L opposite to the small-diameter cylinder portion 34. Functions as a disk joint (pressure release valve joint).
More specifically, the large-diameter cylindrical portion 35 is formed in a cylindrical shape extending in the axial direction with a constant outer diameter that is slightly larger than the outer diameter of the rupture disk 22, and the rupture disk 22 on the lower surface 35 </ b> L. A recess 35M is formed in which the outer peripheral portion of the rupture is inserted, and the rupture disk 22 is joined to the recess 35M. In this case, since the rupture disc 22 is inserted into the recess 35M, the rupture disc 22 can be easily positioned.
The depth of the recess 35M is set to be substantially the same as the thickness of the rupture disc 22.

The lower holder 32 is formed in a fitting cylinder shape that fits into the upper holder 31, and is formed of a resin material such as polypropylene having stretchability and electrical insulation.
More specifically, the lower holder 32 is connected to the fitting cylinder part 37 that fits to the outer peripheral surface 35G of the large-diameter cylinder part 35 of the upper holder 31, and one end of the fitting cylinder part 37. And a flat plate guard portion 38 that covers the outer peripheral edge of the rupture disk 22 attached to the rim, and is integrally manufactured by resin molding.
The fitting cylinder part 37 has an inner peripheral surface 37N having substantially the same diameter as the outer diameter of the large diameter cylinder part 35 of the upper holder 31, and its length (length along the axial direction (see FIG. 4)) L1 is set. The large diameter cylindrical portion 35 is formed to have the same length L2 (length along the axial direction (see FIG. 4)) L2. As a result, as shown in FIG. 3, all of the outer peripheral surface 35 </ b> G of the large-diameter cylindrical portion 35 exposed in the battery case 15 can be covered by the fitting cylindrical portion 37.

The flat plate-shaped guard portion 38 has an outer peripheral surface 38G continuous with the outer peripheral surface 37G of the fitting cylinder portion 37, and the inner peripheral surface 38N has an inner diameter that escapes the protruding portion 22T protruding below the rupture disk 22. Is formed.
Further, the thickness (length along the axial direction) L <b> 3 of the guard portion 38 is formed so as to protrude downward from the rupture disc 22. Thus, the guard portion 38 can cover the outer peripheral edge of the rupture disk 22. Accordingly, for example, when the pressure release valve unit 21 is placed on a table or the like, it is possible to avoid a situation in which the rupture disk 22 directly contacts the table or the like and is damaged.

  As shown in FIGS. 3 and 4, the upper surface 38U of the guard portion 38 abuts on an annular lowermost end portion 35L1 formed on the outer peripheral end of the lower surface 35L of the upper holder 31, and this contact causes the lower holder 32 to Further upward movement is restricted, and the fitting cylindrical portion 37 of the lower holder 32 is positioned at a position covering the entire outer peripheral surface 35G of the large diameter cylindrical portion 35 of the upper holder 31. That is, the guard part 38 also serves as a positioning part for positioning the mounting position of the lower holder 32.

The assembly of the pressure release valve unit 21 is performed by a first step of attaching the rupture disk 22 to the upper holder 31 and a second step of attaching the lower holder 32.
FIG. 5 shows the first step. As shown in FIG. 5, in the first step, the rupture disc 22 is inserted into the recess 35M provided on the lower surface 35L of the upper holder 31, and the outer periphery of the rupture disc 22 is joined to the upper holder 31 by welding. This welding is performed so that there is no gap between the rupture disk 22 and the upper holder 31.

FIG. 6 shows the second step. As shown in FIG. 6, in the second step, the lower holder 32 is fitted into the upper holder 31 to which the rupture disk 22 is attached. By this fitting, the upper holder 31 and the lower holder 32 are friction-joined and connected to each other.
In this case, since the lower holder 32 side made of a soft resin material as compared with the metal upper holder 31 is bent by its own elasticity, the upper holder 31 and the lower holder 32 can be easily fitted together. The engagement force can be sufficiently ensured by the expansion / contraction repulsive force (elastic force) of the lower holder 32. That is, since the upper holder 31 and the lower holder 32 can easily secure a sufficient fitting force by the friction fitting force generated by the elasticity of the lower holder 32, the upper holder 31 and the lower holder 32 are welded or the like. It is not necessary to join.
In this way, the pressure relief valve unit 21 can be assembled by simple operations such as welding the rupture disk 22 to the upper holder 31 and attaching the lower holder 32 to the upper holder 31 by fitting.

FIG. 7 shows a comparative example. In the pressure release valve unit 121 of this comparative example, a disk holder 124 in which both the upper holder 131 and the lower holder 132 are formed of a metal material is employed. In this configuration, in order to connect the upper holder 131 and the lower holder 132 by welding, welding work of the rupture disk 22 (in FIG. 7, the welding location is indicated by α), the upper holder 131 and the lower holder 132 are connected. Welding work (in FIG. 7, the welding location is indicated by symbol β), and the welding work increases.
In this type of pressure relief valve unit 121, since airtightness is required, it is desired to avoid defects due to welding work as much as possible. For this reason, an increase in welding work leads to an increase in the defect rate. Moreover, since the disk holder 124 is made of metal, the electrode terminals 17 and 18 (see FIG. 1) in the battery case 15 and the disk holder 124 may come into contact with each other, causing an internal short circuit.

In addition, in the comparative example, since the lower holder 132 is made of metal, the thickness cannot be increased due to weight restrictions, and there is a gap S between the lower holder 132 and the lower surface 131L of the upper holder 131. Becomes empty. In this configuration, in order to suppress the upward movement of the lower holder 132, the upper holder 131 requires a notch 131K that suppresses the upward movement of the lower holder 132, resulting in a complicated shape.
Further, the diameter of the upper holder 131 is increased by the amount of the cutout 131K, and the diameter of the lower holder 132 is increased so as to cover the entire outer peripheral surface 131G of the upper holder 131. It is difficult from.

On the other hand, in this embodiment, as described above, the welding work required for assembling the pressure release valve unit 21 can be reduced to one time, so that the welding work can be simplified as compared with the comparative example. The defect rate due to welding work can be reduced. Moreover, since the lower holder (second holder) 32 has electrical insulation, for example, depending on the size of the battery, the space between the pressure relief valve unit 21 and the pair of electrode terminals 17 and 18 becomes narrower. Although there is a possibility that the electrode terminals 17 and 18 may be short-circuited with each other, the lower holder 32 positioned on the outermost side of the contacting pressure release valve unit 21 is electrically insulating, so that an internal short circuit can be prevented. it can.
Note that, regardless of the electrode terminals, it is possible to prevent an internal short circuit of different polarity components arranged in the vicinity of the pressure release valve unit in the battery.
Furthermore, compared to the case where the disc holder 24 is entirely made of metal, it becomes easy to avoid the complicated shape and weight.
As a result, the disc holder 24 can prevent damage to the rupture disc 22 and prevent internal short circuit and improve assembly.

Further, in this configuration, as shown in FIG. 1, the lower holder 32 having electrical insulation covers all of the outer peripheral surface 35G exposed in the battery case 15 in the metal upper holder 31, so that an internal short circuit is achieved. Can be prevented more effectively.
2 and 3, the lower holder 32 includes a fitting cylinder portion 37 that covers the outer peripheral surface 35G exposed in the battery case 15 of the upper holder (first holder) 31, and a rupture disc. And the guard portion 38 that functions as a cover portion that covers the outer peripheral edge of the upper portion 22, and when the lower holder 32 is fitted, the guard portion 38 comes into contact with the end surface (lower surface 35L) of the upper holder 31, Since the fitting cylinder part 37 is positioned at a position covering the entire outer peripheral surface 35G exposed in the battery case 15 of the upper holder 31, the attachment position of the lower holder 32 can be easily set to an appropriate position.

In addition, since the rupture disc 22 attached to the lower holder 32 is covered with the guard portion 38 in contact with the lower holder 32, the empty space below the lower holder 32 can be used efficiently. The thickness can be secured, and the strength of the guard portion 38 can be easily obtained.
Furthermore, since the lower holder 32 is made of resin, the weight can be reduced as compared with a case where the lower holder 32 is made of metal, so that the pressure release valve unit 21 can be reduced in weight, and thus the lithium ion battery 10 can be reduced in weight. It is possible to reduce the cost of the lower holder 32.

In the above embodiment, the case where the present invention is applied to the pressure relief valve structure of the lithium ion battery 10 has been described. However, the present invention may be applied to a pressure relief valve structure of a battery other than the lithium ion battery 10.
In the above-described embodiment, the case where the lower holder 32 is made of resin has been described. However, other materials having electrical insulation may be applied.
Moreover, although the case where the rupture disc 22 was used for the pressure release valve was described in the above embodiment, other pressure release valves may be used.
Further, the structure and shape of the battery 10 and the disk holder 24 may be changed as appropriate without departing from the scope of the present invention.

10 Lithium ion battery (Battery with pressure relief valve)
11 Battery case 12 Power generation element 13 Lid (lid)
15 Battery case 19 Through hole 22 Rupture disc (pressure release valve)
24 Disc holder 31 Upper holder (first holder)
32 Lower holder (second holder)
34 Small-diameter cylindrical portion of upper holder 35 Large-diameter cylindrical portion of upper holder 37 Fitting cylindrical portion of lower holder 38 Guard portion (covering portion) of lower holder

Claims (6)

A pressure relief valve in which a through hole is provided in the lid of the battery case having a bottomed battery case having one end opened and a lid that closes the opening of the battery case, and a disk holder that holds the pressure relief valve is attached to the through hole. With batteries,
The lid is insulated from the electrode terminal of the battery,
The disk holder has a first metal holder that is welded to the through hole to which the pressure release valve is welded, and is fitted to the outer peripheral surface of the first holder to protect the pressure release valve and has electrical insulation. A battery with a pressure relief valve comprising two holders. A pressure relief valve in which a through hole is provided in the lid of the battery case having a bottomed battery case having one end opened and a lid that closes the opening of the battery case, and a disk holder that holds the pressure relief valve is attached to the through hole. With batteries,
  The disk holder has a first metal holder that is welded to the through hole to which the pressure release valve is welded, and is fitted to the outer peripheral surface of the first holder to protect the pressure release valve and has electrical insulation. With two holders,
  The battery with a pressure relief valve, wherein the second holder covers all outer peripheral surfaces exposed in the battery case in the first holder. The second holder integrally includes a cylindrical portion that covers an outer peripheral surface exposed in the battery case in the first holder and a cover portion that covers an outer peripheral edge of the pressure release valve. 3. The battery with a pressure relief valve according to claim 1, wherein the cover portion is in contact with the first holder to position the cylindrical portion at a position covering the entire outer peripheral surface of the first holder.   The battery with a pressure relief valve according to any one of claims 1 to 3, wherein the second holder is made of a resin.   The battery with a pressure relief valve according to any one of claims 1 to 4, wherein the pressure relief valve is a rupture disk. The said battery is a lithium ion secondary battery, The battery with a pressure release valve as described in any one of Claim 1 thru | or 5 characterized by the above-mentioned.

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