JP2015210950A - Power storage device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress deterioration in sealability of an injection hole by a seal member, the deterioration being caused by the deformation of the seal member associated with the shrink fit of a rivet member to a body portion.SOLUTION: In a secondary battery, an electrode assembly and an electrolyte are accommodated in a case comprising a case body and a lid. An injection hole of the electrolyte is formed to the lid of the case. The injection hole is sealed with a rivet member 20. The rivet member 20 includes a tubular body portion 21 with a bottom, a flange 22 at one end of the body portion 21 in an axial direction, and an annular seal member 40 integrally assembled by shrink fit to the body portion 21. In the rivet member 20, the body portion 21 is inserted into the injection hole from the other end thereof in the axial direction. The seal member 40 has an escape space for escaping the deformation at an inner peripheral part 41 of the seal member 40 along an inner peripheral edge, the deformation being associated with shrink fit to the body portion 21.

Description

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

  A vehicle such as an EV (Electric Vehicle) or a PHV (Plug in Hybrid Vehicle) is equipped with a secondary battery such as a lithium ion battery as a power storage device that stores power supplied to an electric motor serving as a prime mover. This type of secondary battery includes, for example, an electrode assembly in which a positive electrode having a positive electrode active material layer on a metal foil and a negative electrode having a negative electrode active material layer on a metal foil are insulated with a separator and laminated in layers. Have. The secondary battery is configured by accommodating an electrode assembly and an electrolytic solution in a case.

  The electrolyte solution is injected into the case from a liquid injection hole penetrating in the thickness direction of the case wall constituting the case. In the secondary battery described in Patent Document 1, a rivet member is used as a sealing structure for the liquid injection hole. As shown in FIG. 8, in the secondary battery of Patent Document 1, the liquid injection hole 51 a of the case wall 51 is sealed with a rivet member 53. The rivet member 53 includes a trunk portion 54, a flange 55 that covers the peripheral surface of the liquid injection hole 51a, and a caulking portion 56 that covers the rear surface of the liquid injection hole 51a. An annular seal member 58 is provided between the flange 55 of the rivet member 53 and the case wall 51 so as to be in close contact with the peripheral surface of the liquid injection hole 51 a and the lower surface of the flange 55. The sealing member 58 seals the peripheral surface of the liquid injection hole 51a in the case wall 51 and the lower surface of the flange 55, thereby suppressing leakage of the electrolytic solution from the liquid injection hole 51a.

JP 2010-277936 A

  By the way, in order to simplify the sealing operation of the liquid injection hole 51a, it is conceivable that the seal member 58 is fitted into the body portion 54 of the rivet member 53 by interference fitting and assembled together. If it does in this way, the sealing member 58 can also be arrange | positioned now at the peripheral part surface of the liquid injection hole 51a in the case wall 51 only by inserting the trunk | drum 54 in the liquid injection hole 51a.

  However, when the sealing member 58 is fitted to the barrel portion 54 of the rivet member 53, the inner circumferential portion 59 of the seal member 58 to which the barrel portion 54 is fitted extends from the barrel portion 54 in a direction perpendicular to the axial direction. When the stress acts, the inner peripheral portion 59 of the seal member 58 is compressed and deformed so as to increase its thickness. For this reason, since the surface pressure of the seal member 58 becomes excessively high at the inner peripheral portion 59, the surface pressure acting at other locations in the seal member 58 is reduced. And in the state which inserted the trunk | drum 54 in the liquid injection hole 51a, there exists a possibility that the sealing performance of the liquid injection hole 51a by the sealing member 58 may fall.

  The present invention has been made paying attention to such problems existing in the prior art, and its purpose is to seal the seal member due to the deformation of the seal member due to the interference fit of the rivet member to the body. An object of the present invention is to provide a power storage device capable of suppressing a decrease in sealing performance of a liquid injection hole by a member.

In the following, means for achieving the above object and its effects are described.
A power storage device that solves the above problem is a power storage device in which an electrode assembly and an electrolytic solution are housed in a case. A rivet member for stopping is provided. The rivet member includes a bottomed cylindrical body, a flange at one end of the body in the axial direction, and an annular seal member assembled integrally by an interference fit to the body. The rivet member is inserted into the liquid injection hole from the other end in the axial direction, and the seal member has a clearance space for releasing deformation of the inner peripheral portion of the seal member due to the interference fit to the barrel. It has along the periphery.

  In the above configuration, when a stress in a direction perpendicular to the axial direction acts on the seal member from the trunk portion in accordance with an interference fit of the seal member to the trunk portion of the rivet member, the seal member is orthogonal to the axial direction. Is compressed. At this time, it is suppressed that the surface pressure of the seal member integrally assembled by the interference fit to the body portion becomes excessively high at the inner peripheral portion.

  That is, the seal member is compressed in a direction orthogonal to the axial direction in accordance with the interference fit of the rivet member to the body portion, but the seal member is deformed so as to escape into the escape space at the inner peripheral portion. For this reason, it is suppressed that the surface pressure to the direction orthogonal to an axial direction becomes high too much only in the inner peripheral part of a seal member. Therefore, it can suppress that the sealing performance of the injection hole by a sealing member falls due to a deformation | transformation of the sealing member accompanying the interference fitting to the trunk | drum of a rivet member.

  ADVANTAGE OF THE INVENTION According to this invention, it can suppress that the sealing performance of the liquid injection hole by a sealing member falls due to the deformation | transformation of the sealing member accompanying the interference fitting to the trunk | drum of a rivet member.

The disassembled perspective view which shows a secondary battery. The perspective view which shows a secondary battery. Sectional drawing which shows the rivet member before a sealing member is fitted by the trunk | drum. The top view which shows the sealing member before fitting by the trunk | drum. Sectional drawing which shows the rivet member after a sealing member was fitted by the trunk | drum. The top view which shows the sealing member after being fitted by the trunk | drum. Sectional drawing which shows the state by which the liquid injection hole was sealed by the rivet member. Sectional drawing which shows the conventional secondary battery.

Hereinafter, an embodiment embodying a power storage device will be described with reference to FIGS.
As shown in FIGS. 1 and 2, the secondary battery 10 is configured by housing an electrode assembly 12 and an electrolytic solution in a case 11. The case 11 includes a bottomed square cylindrical case main body 13 and a rectangular flat lid 14 that closes an opening 13 a for inserting the electrode assembly 12 into the case main body 13. In the present embodiment, the lid body 14 corresponds to a case wall constituting the case 11. Both the case body 13 and the lid body 14 are 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. Ring-shaped insulating members 17 for insulating from the case 11 are attached to the positive terminal 15 and the negative terminal 16, respectively. Further, the positive electrode terminal 15 and the negative electrode terminal 16 are exposed outside the case 11 from the lid body 14.

  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 sides of a positive metal foil (for example, an aluminum foil). A negative electrode is equipped with a negative electrode active material layer on both surfaces of negative electrode metal foil (for example, 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.

  Of both surfaces of the lid body 14, a surface located inside the case 11 is a back surface 14 a and a surface located outside the case 11 is a surface 14 b. The lid body 14 has a liquid injection hole 14c penetrating in the thickness direction. The liquid injection hole 14c is sealed by the rivet member 20, and the leakage of gas and electrolyte from the case 11 is prevented.

Next, the rivet member 20 before being inserted into the liquid injection hole 14c will be described.
As shown in FIGS. 1 and 3, the rivet member 20 is open at one end in the axial direction and has a hollow cylindrical body 21 having a bottom wall 21 a at the other end in the axial direction, and one end in the axial direction of the body 21. It has the annular flange 22 provided in the opening edge, and the mandrel 30 accommodated in the inside of the trunk | drum 21. FIG. The body portion 21 and the flange 22 are integrally made of aluminum and are integrally formed by press molding.

  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 other axial end side, that is, on the lower side, and is connected to the accommodating portion 21 d and has a large diameter portion. A communication portion 21 e having a smaller diameter than 31 is formed. Further, in the body portion 21, an insertion portion 21f having an inner diameter larger than that of the communication portion 21e is formed on one end side in the axial direction of the communication portion 21e, that is, on the upper side.

The flange 22 has an annular convex portion 22 b that protrudes downward on the lower surface 22 a and surrounds the body portion 21.
The mandrel 30 is provided with a rod-shaped operation part 32, a large-diameter part 31 larger in diameter than the operation part 32, a boundary between the operation part 32 and the large-diameter part 31, and a fragile part 33 smaller in diameter than the operation part 32. have. The mandrel 30 is made of stainless steel, for example. In the state where the mandrel 30 is accommodated in the body portion 21, the large-diameter portion 31 of the mandrel 30 is accommodated in the accommodation portion 21 d of the body portion 21, and the fragile portion 33 of the mandrel 30 communicates with the body portion 21. It is accommodated in the part 21e. Further, the operation portion 32 of the mandrel 30 is accommodated in the insertion portion 21 f of the trunk portion 21, and the distal end of the operation portion 32 protrudes from the trunk portion 21. In addition, the hardness of the mandrel 30 is larger than the hardness of the trunk portion 21.

In the rivet member 20, an annular seal member 40 is fitted to the outer peripheral surface of the trunk portion 21. The seal member 40 is made of, for example, resin or rubber.
As shown in FIG. 4, the inner peripheral portion 41 of the seal member 40 is sandwiched between a plurality of (in this embodiment, five) convex portions 41 a protruding inward and two convex portions 41 a adjacent in the circumferential direction. And a plurality of (in this embodiment, five) recesses 41b that are recessed outward. The apex of the convex portion 41 a and the apex of the concave portion 41 b are connected by a linear inner peripheral edge in the circumferential direction of the inner peripheral portion 41 of the seal member 40.

  The space S1 formed by virtually connecting the vertices of the plurality of convex portions 41a has a circular shape, and the sealing member 40 has a circular inner diameter slightly smaller than the outer diameter of the body portion 21. The inner peripheral portion 41 is formed. Further, in the inner peripheral portion 41 of the seal member 40, the inner peripheral portion 41 of the seal member 40, which is the sum of the space S2 composed of a plurality of concave portions 41b that are outer spaces in the circumferential direction than the space S1, and the space S1. The overall volume is larger than the volume in the direction orthogonal to the axial direction of the body portion 21.

  As shown in FIG. 5, when the seal member 40 is fitted to the body portion 21, the inner peripheral portion 41 of the seal member 40 is compressed and deformed. That is, the seal member 40 is fitted into the body portion 21 with an interference fit, and is integrally assembled with the body portion 21.

  As shown in FIG. 6, the stress in the direction perpendicular to the vertical direction acts on the seal member 40 from the barrel 21 with the interference fit to the barrel 21, and the direction perpendicular to the vertical direction. The sealing member 40 is compressed to the heel. For this reason, in the inner peripheral part 41 of the sealing member 40, the convex part 41a is dented toward the outer side of the sealing member 40 in the direction orthogonal to the up-down direction. And in the sealing member 40, the deformation | transformation which the recessed part 41b becomes narrow in the circumferential direction by the part which the convex part 41a dented in this way arises. That is, the deformation in which the concave portion 41b is narrowed in the circumferential direction of the seal member 40 is caused by the difference in the space S1 of the seal member 40 with respect to the volume perpendicular to the axial direction of the body portion 21. In addition, in the rivet member 20 before the seal member 40 is fitted to the body portion 21 and inserted into the liquid injection hole 14c, the space S2 is narrowed by the above-described deformation of the concave portion 41b of the seal member 40. The volume of the space S <b> 2 of the seal member 40 before being fitted to the trunk portion 21 is a volume capable of absorbing the deformation of the seal member 40 due to the interference fit to the trunk portion 21.

Next, the rivet member 20 inserted in the liquid injection hole 14c will be described.
As shown in FIG. 7, when the rivet member 20 is inserted into the liquid injection hole 14 c from the bottom wall 21 a of the body portion 21, the bottom wall 21 a of the body portion 21 is positioned in the case 11, and the flange 22 is outside the case 11. It is fastened to the lid body 14 in a state of being positioned at the position. In the mandrel 30, the operation portion 32 and the large-diameter portion 31 are separated from the weak portion 33, and the operation portion 32 is removed from the body portion 21. By the operation of removing the operation portion 32 from the body portion 21, the large-diameter portion 31 of the mandrel 30 is press-fitted into the body portion 21 to expand the diameter of the body portion 21, thereby forming the caulking portion 24. The outer peripheral surface of the caulking portion 24 is in close contact with the periphery of the liquid injection hole 14 c on the back surface 14 a of the lid body 14 and seals the liquid injection hole 14 c.

  When the rivet member 20 is inserted into the liquid injection hole 14 c, the upper surface 40 a of the seal member 40 faces the lower surface 22 a of the flange 22, and the lower surface 40 b of the seal member 40 faces the surface 14 b of the lid body 14. It will be in the state.

  The rivet member 20 is fastened to the lid body 14 by the caulking portion 24 and the flange 22, and the seal member 40 is sandwiched between the lower surface 22 a of the flange 22 and the surface 14 b of the lid body 14. The axial force accompanying the fastening acts on the seal member 40 via the lower surface 22a of the flange 22 and the annular convex portion 22b, and the seal member 40 is compressed in the axial direction.

  A predetermined surface pressure is generated between the lower surface 22 a of the flange 22 and the upper surface 40 a of the seal member 40 by closely contacting the lower surface 22 a and the annular protrusion 22 b of the flange 22 and the upper surface 40 a of the seal member 40. Similarly, when the lower surface 40b of the seal member 40 and the surface 14b of the lid 14 are in close contact with each other, a predetermined surface pressure is generated between the lower surface 40b of the seal member 40 and the surface 14b of the lid 14. The liquid injection hole 14c is sealed outside the case 11 by the seal member 40 in which surface pressure is generated on the upper surface 40a and the lower surface 40b.

Next, the operation of the secondary battery 10 will be described.
With the interference fit to the body portion 21, the seal member 40 is deformed so that the convex portion 41a of the inner peripheral portion 41 of the seal member 40 is compressed and the thickness is increased. At this time, the inner peripheral portion 41 of the seal member 40 is deformed so as to escape into the space S2 as the escape space.

Therefore, according to the present embodiment, the following effects can be obtained.
(1) When the stress in the direction orthogonal to the axial direction acts on the seal member 40 from the trunk portion 21 in accordance with the interference fit of the seal member 40 to the trunk portion 21 of the rivet member 20, the seal member 40 has an inner circumference. The part 41 is deformed so as to escape to the space S2 as the escape space. For this reason, it is suppressed that the surface pressure in the direction orthogonal to the axial direction becomes excessively high only by the inner peripheral portion 41 of the seal member 40. Therefore, it is possible to suppress a decrease in the sealing performance of the liquid injection hole 14c by the seal member 40 due to the deformation of the seal member 40 due to the interference fit of the rivet member 20 to the body portion 21.

In addition, you may change the said embodiment as follows.
The number of the convex portions 41a and the concave portions 41b of the sealing member 40 may be changed. Further, the shape of the inner peripheral portion 41 of the seal member 40 may be changed. For example, the inner circumferential portion 41 of the seal member 40 is formed to have a thickness smaller than the outer circumferential thickness over the entire circumference, and the space generated between the outer circumferential surface and the inner circumferential surface in the axial direction is You may make it function as an escape space which escapes a deformation | transformation of the sealing member 40. FIG.

  ○ The annular protrusion 22b may be omitted. Further, instead of the annular convex portion 22b, a convex portion protruding toward the seal member 40 may be provided on the surface 14b of the lid body 14. Moreover, you may provide both the cyclic | annular convex part 22b and the convex part of the cover body 14. FIG.

A side wall or bottom wall constituting the case body 13 may be used as a case wall, and a liquid injection hole 14c may be provided in the case wall and sealed with the rivet member 20.
O A foil made of a metal other than aluminum may be adopted as the positive electrode metal foil.

O A foil made of a metal other than copper may be employed as the negative electrode metal foil.
○ Only one side of the positive electrode may have a positive electrode active material layer.
○ Only one side of the negative electrode may have a negative electrode active material layer.

The electrode assembly 12 may be a wound type.
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 layer and the negative electrode active material layer and transfer charges.

○ The shape of the case 11 may be changed. For example, the case 11 may be cylindrical.
The present invention may be embodied in a power storage device such as an electric double layer capacitor.
Next, a technical idea that can be grasped from the above embodiment and another example will be additionally described.

  (A) The power storage device is a secondary battery.

  DESCRIPTION OF SYMBOLS 10 ... Secondary battery, 11 ... Case, 12 ... Electrode assembly, 13 ... Case main body, 14 ... Cover body, 14c ... Injection hole, 20 ... Rivet member, 21 ... Trunk part, 21a ... Bottom wall, 22 ... Flange 30 ... Mandrel, 40 ... Seal member, 41 ... Inner circumference, 41a ... Convex part, 41b ... Concave part, S1, S2 ... Space.

Claims (1)

A power storage device in which an electrode assembly and an electrolytic solution are housed in a case,
The case wall constituting the case has a liquid injection hole for the electrolytic solution, and includes a rivet member for sealing the liquid injection hole.
The rivet member includes a bottomed cylindrical body, a flange at one end in the axial direction of the body, and an annular seal member integrally assembled by an interference fit to the body,
In the rivet member, the body portion is inserted into the liquid injection hole from the other axial end,
The power storage device according to claim 1, wherein the seal member has a clearance space along the inner peripheral edge for releasing deformation of the inner peripheral portion of the seal member due to the interference fit with the body portion.