JP6201797B2 - Power storage device - Google Patents

Description

  The present invention relates to a power storage device in which an electrode assembly and an electrolytic solution are housed in a case.

  Power storage devices such as secondary batteries and capacitors are widely used as power sources because they can be recharged and can be used repeatedly. Generally, a secondary battery (power storage device) having a large capacity includes a case, and an electrode assembly and an electrolytic solution are accommodated in the case. In assembling the secondary battery, after the electrode assembly is accommodated in the main body member of the case, the lid member of the case is welded to the main body member to close the main body member. Then, after pouring electrolyte solution into the case from the liquid injection hole of the lid member, the liquid injection hole is sealed.

  As a liquid injection hole sealing structure, there is one using a rivet (see, for example, Patent Document 1). As shown in FIG. 7, in the sealed battery of Patent Document 1, the electrolyte injection hole 81 a of the sealing plate 81 is sealed with a rivet 83. The rivet 83 includes a shaft portion 84, a flange portion 85 that covers the peripheral surface of the electrolyte injection hole 81a, and a crimping portion 86 that covers the back surface of the peripheral portion of the electrolyte injection hole 81a. Further, a gasket 88 in close contact with the peripheral surface of the electrolyte injection hole 81 a and the back surface of the flange 85 is interposed between the flange 85 of the rivet 83 and the sealing plate 81.

  In the sealing plate 81, an annular first convex portion 89a and an annular second convex portion 89b positioned outside the first convex portion 89a are provided on the peripheral surface of the electrolyte solution injection hole 81a. . In the rivet 83, an annular third convex portion 85 a that protrudes toward the gasket 88 is provided on the back surface of the flange portion 85. The third convex portion 85a is formed at a position that does not overlap with the first convex portion 89a in a plan view of the sealing plate 81 but overlaps with the second convex portion 89b.

  The gasket 88 is sandwiched between the first convex portion 89a and the second convex portion 89b and the flange portion 85, and the third convex portion 85a is in close contact with the gasket 88, and the electrolyte injection hole in the sealing plate 81 The peripheral surface of 81a and the back surface of the flange 85 are sealed.

JP 2010-277936 A

  By the way, in order to simplify the sealing operation of the electrolyte injection hole 81a, in Patent Document 1, a gasket 88 is fitted into the outer peripheral surface of the shaft portion 84 of the rivet 83 by an interference fit, and is assembled integrally. This is because the gasket 88 can be disposed on the peripheral surface of the electrolyte injection hole 81a in the sealing plate 81 only by inserting the shaft portion 84 into the electrolyte injection hole 81a.

  However, when the gasket 88 is tightly fitted to the shaft portion 84 of the rivet 83, the inner peripheral surface of the gasket 88 is in close contact with the outer peripheral surface of the shaft portion 84, and the inner peripheral portion of the gasket 88 is compressed in the radial direction to increase the thickness. It is in a deformed state. For this reason, when the crimping portion 86 is formed with a predetermined axial force for sealing the electrolyte injection hole 81a, the surface pressure of the gasket 88 becomes excessively high at the inner peripheral portion. The acting surface pressure is reduced. And since the surface pressure of the gasket 88 becomes excessively high at the inner peripheral portion, the portion where the gasket 88 is compressed more strongly than others to improve the sealing performance, that is, the tips of the first convex portion 89a and the second convex portion 89b. The surface pressure generated in the gasket 88 between the surface and the back surface of the flange portion 85 facing the surface decreases. For this reason, there exists a possibility that the sealing performance of the electrolyte solution injection hole 81a by the gasket 88 may fall.

  An object of the present invention is to provide a power storage device capable of sealing a liquid injection hole with a seal member.

  A power storage device for solving the above-mentioned problems includes an electrode assembly and an electrolytic solution housed in a case, and has a liquid injection hole on the wall of the case, and a sealing member for the liquid injection hole The sealing member includes a bottomed cylindrical body, a flange at one axial end of the body, and an annular seal member assembled integrally with the flange. The protrusion has a protrusion protruding toward the seal member from the surface facing the seal member, and the seal member has a recess into which the protrusion is inserted, and the protrusion protrudes toward the seal member. The gist is that the length is longer than the depth of the recess.

  According to this, the sealing member can be integrally assembled to the sealing member by fitting the protruding portion of the flange into the concave portion of the sealing member. In such a sealing member, when the sealing member is fastened to the wall portion and an axial force acts on the sealing member, the sealing member is compressed in the axial direction. Therefore, the surface facing the wall portion of the seal member is in close contact with the outer wall surface of the wall portion, the surface facing the flange is in close contact with the flange, and the liquid injection hole is sealed by the seal member.

  At this time, since the seal member is integrally assembled by fitting the protrusion and the recess, and the inner peripheral portion is not in close contact with the body portion, the surface pressure of the seal member is excessive at the inner peripheral portion as in the interference fit. It is suppressed that it becomes high. And the site | part corresponding to the recessed part in a sealing member is compressed to an axial direction by the protrusion which received the axial force, and a surface pressure increases locally. Therefore, it is possible to prevent the surface pressure in the axial direction from becoming excessively high only at the inner peripheral portion of the seal member, and it is possible to secure the surface pressure of the seal member and ensure the sealing performance of the liquid injection hole.

In the power storage device, the protrusion may have an annular shape surrounding the body portion.
According to this, in the seal member, the surface pressure can be increased at a position surrounding the entire circumference of the liquid injection hole.

  The power storage device is a secondary battery.

  According to the present invention, the liquid injection hole can be sealed by the sealing member.

The disassembled perspective view which shows the secondary battery of embodiment. The perspective view which shows the secondary battery of embodiment. (A) is sectional drawing which shows a sealing member, (b) is a fragmentary sectional view which expands and shows an annular protrusion and an annular recessed part. Sectional drawing which shows a sealing member. (A) is a fragmentary sectional view which shows the state which sealed the liquid injection hole, (b) is an expanded sectional view which shows the state by which the annular protrusion was inserted by the annular recessed part. The disassembled perspective view which shows the sealing member and sealing member of another example. The figure which shows background art.

Hereinafter, an embodiment in which the power storage device is embodied as a secondary battery will be described with reference to FIGS.
As shown in FIGS. 1 and 2, in the secondary battery 10, an electrode assembly 12 and an electrolytic solution are accommodated in a case 11. The case 11 includes a bottomed rectangular tube-shaped main body member 13 and a rectangular flat plate-shaped lid 14 that closes an opening 13 a for inserting the electrode assembly 12 into the main body member 13. In the present embodiment, the lid 14 corresponds to a wall portion constituting the case 11. The main body member 13 and the lid 14 are both made of metal (for example, made of stainless steel or aluminum). The secondary battery 10 is a prismatic battery and is a lithium ion battery.

  A positive electrode terminal 15 and a negative electrode terminal 16 are electrically connected to the electrode assembly 12. A ring-shaped insulating member 17 for insulating from the case 11 is attached to each of the positive terminal 15 and the negative terminal 16. Further, the positive terminal 15 and the negative terminal 16 are exposed from the lid 14 to the outside of the case 11.

  The electrode assembly 12 includes a positive electrode, a negative electrode, and a separator that insulates the positive electrode and the negative electrode. The positive electrode includes a positive electrode active material layer on both surfaces of a positive electrode metal foil (aluminum foil). The negative electrode includes a negative electrode active material layer on both sides of a negative electrode metal foil (copper foil). The electrode assembly 12 has a laminated structure in which a plurality of positive electrodes and a plurality of negative electrodes are alternately laminated, and a separator is interposed between the two electrodes.

  The lid 14 has an inner wall surface 14 a on the surface facing the inner side of the case 11, and an outer wall surface 14 b on the surface facing the outer side of the case 11. The lid | cover 14 is equipped with the liquid injection hole 14c penetrated in the thickness direction. The liquid injection hole 14c is sealed by the sealing member 20, and leakage of gas and electrolyte from the case 11 is prevented.

First, the sealing member 20 before being inserted into the liquid injection hole 14c will be described.
As shown in FIGS. 1 and 3A, the sealing member 20 has a hollow cylindrical body 21 having an opening at one axial end and a bottom wall 21 a at the other axial end, and the body 21. And an annular flange 22 provided at the opening edge of one end in the axial direction. Further, the sealing member 20 includes an annular seal member 40 that is integrated with the flange 22, and a mandrel 30 that is accommodated in the body portion 21.

  The trunk | drum 21 (bottom wall 21a) and the flange 22 are integrally made from aluminum, and are integrally formed by press molding. The trunk portion 21 has a first cylindrical portion 25 near the flange 22 along the axial direction, and a second cylindrical portion 26 closer to the bottom wall 21 a than the first cylindrical portion 25. The first tube portion 25 has a length along the axial direction of the body portion 21 that is longer than the thickness of the lid 14 and a smaller diameter than the second tube portion 26. The 1st cylinder part 25 is arrange | positioned inside the liquid injection hole 14c. The second cylindrical portion 26 is disposed inside the case 11 with respect to the inner wall surface 14 a of the lid 14.

  Inside the body portion 21, an accommodating portion 21 d having a larger diameter than the large diameter portion 31 of the mandrel 30 is formed on the second cylindrical portion 26 side, and is connected to the accommodating portion 21 d and tapered toward the flange 22. In addition, a communication portion 21e having a smaller diameter (reduced diameter) than the large diameter portion 31 is formed. The trunk portion 21 includes an insertion portion 21f whose inner diameter is larger than that of the communication portion 21e on one end side in the axial direction of the first cylindrical portion 25 relative to the communication portion 21e.

  The flange 22 has a seal member side end face 22 a that faces the seal member 40. The flange 22 includes an annular protrusion 22 b that protrudes toward the seal member 40 from the end surface 22 a on the seal member side and that surrounds the first tube portion 25 of the trunk portion 21.

  The seal member 40 has a flange-side end surface 40 a as a surface facing the flange 22, and a lid-side end surface 40 b as a surface facing the outer wall surface 14 b of the lid 14. The seal member 40 has an annular recess 40c that is recessed in an annular shape from the flange-side end surface 40a. The annular recess 40 c is an annular shape that surrounds the inner peripheral edge of the seal member 40.

  As shown in FIG. 3B, the outer diameter R1 of the annular recess 40c in the seal member 40 is slightly smaller than the outer diameter N1 of the annular protrusion 22b in the flange 22, and the inner diameter R2 of the annular recess 40c is the annular protrusion. It is slightly larger than the inner diameter N2 of 22b. For this reason, the thickness W1 along the radial direction of the annular protrusion 22b is slightly longer than the opening width W2 along the radial direction of the annular recess 40c. The seal member 40 is made of resin, but may be made of rubber. As shown in FIG. 3A, the inner diameter H of the seal member 40 is slightly larger than the outer diameter K of the first cylinder portion 25 in the trunk portion 21.

  Further, as shown in FIG. 3B, the length along the protruding direction from the seal member side end face 22 a toward the seal member 40 in the annular protrusion 22 b is defined as a protrusion length L. On the other hand, in the annular recess 40c, a length from the flange side end surface 40a to the lid side end surface 40b is defined as a depth F. The protrusion length L of the annular protrusion 22b is longer than the depth F of the annular recess 40c.

  Therefore, as shown in FIG. 4, the annular protrusion 22b has a size that can be inserted into the annular recess 40c. When the annular protrusion 22b is sandwiched between the annular recesses 40c, the seal member 40 is The flange 22 is assembled so as not to fall. Further, in the sealing member 20 in which the flange 22 and the seal member 40 are integrated from the relationship between the protrusion length L of the annular protrusion 22b and the depth F of the annular recess 40c, the seal member side end face 22a, the flange A slight gap T is defined between the side end faces 40a.

  As shown in FIGS. 1 and 4, the mandrel 30 is provided with a rod-shaped operation part 32, a large-diameter part 31 having a larger diameter than the operation part 32, and a boundary between the operation part 32 and the large-diameter part 31. And a weakened portion 33 having a smaller diameter than the portion 32. The mandrel 30 is made of stainless steel. In the mandrel 30, the large-diameter portion 31 is accommodated in the accommodating portion 21d, and the fragile portion 33 is accommodated in the communicating portion 21e. Further, the operation part 32 is accommodated in the insertion part 21 f, and the tip thereof protrudes from the trunk part 21. In addition, the hardness of the mandrel 30 is larger than the hardness of the trunk portion 21.

Next, the operation of the secondary battery 10 will be described together with the method for sealing the injection hole 14c.
As shown in FIG. 5A, the sealing member 20 is inserted into the liquid injection hole 14c from the second cylindrical portion 26 on the other axial end side, the bottom wall 21a is located in the case 11, and the flange 22 is inserted. Is fastened to the lid 14 in a state of being located outside the case 11. Specifically, the large-diameter portion 31 of the mandrel 30 is press-fitted into the trunk portion 21 to expand the diameter of the second cylindrical portion 26 of the trunk portion 21 to form a caulking portion 24. In the mandrel 30, the operation portion 32 and the large diameter portion 31 are separated from the fragile portion 33, and the operation portion 32 is removed from the body portion 21. The outer peripheral surface of the caulking portion 24 is in close contact with the periphery of the liquid injection hole 14 c in the inner wall surface 14 a of the lid 14 and seals the liquid injection hole 14 c.

  Further, the sealing member 20 is fastened to the lid 14 by the caulking portion 24 and the flange 22, and the seal member 40 is sandwiched between the seal member side end surface 22 a of the flange 22 and the outer wall surface 14 b of the lid 14. ing. An axial force accompanying the fastening acts on the seal member 40 via the seal member side end face 22a and the annular protrusion 22b, and is compressed in the axial direction of the seal member 40.

  5B, the annular protrusion 22b of the flange 22 compresses the inner bottom surface of the annular recess 40c of the seal member 40, and a portion of the seal member 40 that faces the annular protrusion 22b is covered with the lid 14. Is pressed against the outer wall surface 14b. For this reason, in the seal member 40, a predetermined surface pressure is generated between the tip of the annular protrusion 22b and the outer wall surface 14b of the lid 14 facing the tip.

  Further, the surface of the flange 22 on the seal member side end surface 22a excluding the annular protrusion 22b is in close contact with the surface on the flange side end surface 40a of the seal member 40 excluding the annular recess 40c, and the gap T is eliminated. Similarly, the surface of the lid-side end surface 40b of the seal member 40 excluding the portion facing the annular recess 40c is in close contact with the outer wall surface 14b of the lid 14. Therefore, the liquid injection hole 14 c is sealed by the seal member 40 outside the case 11.

According to the above embodiment, the following effects can be obtained.
(1) The annular protrusion 22 b of the flange 22 is fitted into the annular recess 40 c of the seal member 40, and the seal member 40 is integrated with the flange 22. For this reason, in the sealing member 20, the trunk | drum 21 and the sealing member 40 can be handled integrally, and conveyance becomes easy. As for the sealing of the liquid injection hole 14c, if the body 21 is inserted into the liquid injection hole 14c, the sealing member 40 can be disposed around the liquid injection hole 14c. Become.

  (2) Further, the seal member 40 is integrated by inserting and inserting the annular protrusion 22b into the annular recess 40c, and the inner peripheral surface of the seal member 40 is not in pressure contact with the outer peripheral surface of the body portion 21 (an interference fit). is not). For this reason, even if the sealing member 40 receives axial force and is compressed in the axial direction in order to fasten the sealing member 20 to the lid 14, it is suppressed that the surface pressure of the sealing member 40 becomes excessively high at the inner peripheral portion. The And the protrusion length L of the cyclic | annular protrusion 22b was made longer than the depth F of the cyclic | annular recessed part 40c. For this reason, when an axial force is applied to the seal member 40 in order to fasten the sealing member 20 to the lid 14, the seal member 40 can be locally compressed by the annular protrusion 22b. Therefore, in the seal member 40, a desired surface pressure can be reliably generated at the portion where the annular protrusion 22b is inserted, and the periphery of the liquid injection hole 14c can be accurately sealed.

  (3) The annular protrusion 22b is provided so as to surround the trunk portion 21, and the annular protrusion 22b is provided so as to surround the entire circumference of the liquid injection hole 14c. The annular recess 40c is also provided so as to surround the entire circumference of the body portion 21, that is, the entire circumference of the liquid injection hole 14c. For this reason, when the seal member 40 is locally compressed by the annular protrusion 22b, a surface pressure can be generated in the seal member 40 at a position surrounding the liquid injection hole 14c, and the liquid injection hole 14c extends over the entire circumference. Can be sealed.

  (4) The protruding length L of the annular protrusion 22b is made longer than the depth F of the annular recess 40c, and the seal member 40 is locally compressed by the annular protrusion 22b. At this time, the surface excluding the annular protrusion 22b on the seal member side end surface 22a of the flange 22 is in close contact with the surface excluding the annular recess 40c on the flange side end surface 40a of the seal member 40, and the lid side end surface 40b is the lid 14. Close to the outer wall surface 14b. For this reason, while the surface pressure of the sealing member 40 is locally increased by the annular protrusion 22b, the surfaces can be brought into close contact with each other to seal the liquid injection hole 14c.

In addition, you may change the said embodiment as follows.
As shown in FIG. 6, the seal member 50 may be configured to have a plurality of projecting pieces 52 on the inner peripheral surface of an annular base 51. The base 51 has a flange-side end surface 51 a as a surface facing the flange 22 and a lid-side end surface 51 b as a surface facing the outer wall surface 14 b of the lid 14.

  The seal member 50 includes a plurality of protruding pieces 52 that protrude from the inner peripheral surface of the base portion 51 toward the central axis of the base portion 51. The plurality of protruding pieces 52 are arranged at equal intervals along the circumferential direction of the base 51. The thickness of the projecting piece 52 and the thickness of the base 51 are the same. When the direction in which the protruding pieces 52 extend from the inner peripheral surface of the base portion 51 toward the central axis of the seal member 50 is defined as the protruding direction of the protruding pieces 52, the diameter of the virtual circle C connecting the tips of all protruding pieces 52 in the protruding direction. Is slightly larger than the outer diameter of the first cylindrical portion 25 in the trunk portion 21. For this reason, a gap is formed between the tip of each protruding piece 52 and the outer peripheral surface of the first cylindrical portion 25. Further, the sealing member 50 has an annular recess 51c in the base 51 that is recessed in an annular shape from the flange-side end surface 51a.

  And the trunk | drum 21 is inserted inside the protrusion 52, and the cyclic | annular protrusion 22b of the flange 22 fits in the cyclic | annular recessed part 51c in the state which the front-end | tip of the protrusion direction of all the protrusions 52 was slightly spaced apart from the trunk | drum 21. The seal member 50 is integrated with the flange 22.

  In the embodiment, the projecting portion is the annular projecting portion 22b extending over the entire circumference of the flange 22. However, the projecting portion may be provided at a plurality of locations at intervals in the circumferential direction of the flange 22.

In this case, the recess may be the annular recess 40c as in the embodiment, or may be a plurality of recesses provided in a portion facing the protrusion.
In the embodiment, the lid 14 is a wall portion, but the side wall or bottom wall of the main body member 13 may be a wall portion, and a liquid injection hole 14 c may be provided in the wall portion and sealed with the sealing member 20.

  The positive electrode has a positive electrode active material layer on both sides of the positive electrode metal foil, but may have a positive electrode active material layer only on one side of the positive electrode metal foil. Similarly, although the negative electrode has the negative electrode active material layer on both sides of the negative electrode metal foil, the negative electrode may have the negative electrode active material layer only on one side of the negative electrode metal foil.

The power storage device may be applied not to the secondary battery 10 but to another power storage device such as an electric double layer capacitor.
In the embodiment, the stacked type is described as the electrode assembly 12, but a wound type may be used.

  The secondary battery 10 is a lithium ion secondary battery, but is not limited thereto, and may be another secondary battery. In short, any material may be used as long as ions move between the positive electrode active material and the negative electrode active material and transfer charge.

Next, the technical idea that can be grasped from the above embodiment and other examples will be described below.
(A) The power storage device having an annular shape extending over the entire circumferential direction of the seal member.

  (B) The flange has a seal member side end surface facing the seal member, the seal member has a flange side end surface facing the seal member side end surface, and the seal member side end surface and the flange side end surface Are power storage devices in close contact with each other.

  F: Depth, L ... Projection length, 10 ... Secondary battery as power storage device, 11 ... Case, 12 ... Electrode assembly, 14 ... Lid as wall, 14c ... Injection hole, 20 ... Sealing member , 21 ... trunk, 22 ... flange, 22b ... annular projection as projection, 40, 50 ... seal member, 40c, 51c ... annular recess as recess.

Claims (3)

The electrode assembly and the electrolyte are accommodated in the case,
While having a liquid injection hole in the wall of the case, a sealing member for the liquid injection hole,
The sealing member is
A cylindrical body with a bottom;
A flange at one axial end of the barrel,
An annular seal member assembled integrally with the flange,
An inner diameter of the seal member is larger than an outer diameter of the trunk portion,
The flange has a protrusion protruding toward the seal member from the surface facing the seal member;
The seal member has a recess into which the protrusion is inserted,
The protruding length of the protrusion toward the seal member is longer than the depth of the recess.
  The power storage device according to claim 1, wherein the protrusion has an annular shape surrounding the body portion.   The power storage device according to claim 1, wherein the power storage device is a secondary battery.