JP2017076475A - Power storage device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power storage device arranged so that a liquid inlet can be used as a hole for replenishment of an electrolytic solution in re-using the power storage device, and a seal structure of the liquid inlet serves as a safety valve.SOLUTION: A secondary battery 10 is a power storage device comprising: an electrode assembly 12; and a case 11 including a lid (top wall) 15, in which the electrode assembly is encased, provided that the lid has a hole 30 formed therein and allowing an electrolytic solution 13 to be poured in the secondary battery. The hole 30 has a large-diameter part 31 with internal threads 31a formed therein, and a small-diameter part 32 formed in its bottom part 31b, and is formed so that the large- and small- diameter parts adjoin to each other. The secondary battery further comprises a seal member 33 made of an elastic material and arranged in the bottom part 31b; the seal member covers the bottom part 31b and has gas-passage holes 33a formed at positions where the gas-passage holes never overlap the small-diameter part 32. To the large-diameter part 31, a fastening member 35 having a through-hole 35b formed in its axial direction is attached so as to be able to adjust a pressing force for pressing the seal member 33 against the bottom part 31b when being screw-fitted with the internal threads 31a.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a power storage device, and more particularly, to a power storage device characterized by a hole sealing structure into which an electrolyte can be injected.

  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. When manufacturing this type of secondary battery, a battery element such as an electrode assembly is accommodated in the case, and the opening of the case is closed with a lid. In addition, the secondary battery case is provided with a liquid injection hole (liquid injection port) for injecting an electrolytic solution into the closed case. It is sealed by.

  For example, in the case of a lithium ion secondary battery, after the secondary battery is assembled, an aging process is performed in which the secondary battery is charged and discharged to activate the secondary battery. In this process, gas is generated in the secondary battery. For this reason, it is necessary to seal the case after exhausting the gas generated in the process during the aging process from the case. Therefore, when performing the aging process, the liquid injection hole is temporarily sealed, and after the aging process is completed, the temporary sealing is released and the gas is discharged, and then the liquid injection hole is fully sealed.

  As shown in FIG. 6, the sealed battery of Patent Document 1 includes a screw hole 62 provided in the lid 61 of the outer case, and a screw 63 inserted into the screw hole 62 and fastened. The bottom surface 64 is provided with an opening (a liquid injection port) 65 which is an inner opening communicating with the inside of the exterior case and whose opening diameter is smaller than the hole diameter on the case surface of the screw hole 62. Between the bottom surface 64 of the screw hole 62 and the tip 63a of the screw 63, a hole inner seal member 66 that covers the opening 65 is disposed. The hole inner seal member 66 is pressed against the bottom surface 64 of the screw hole 62 by the tightening force of the screw 63 to seal the opening 65. Further, a hole external seal member 67 is interposed between the head 63 b of the screw 63 and the lid 61, and the hole external seal member 67 seals a gap between the head 63 b of the screw 63 and the lid 61. Yes. The hole exterior seal member 67 is accommodated in an annular groove 68 formed on the lower surface of the head 63 b of the screw 63.

  Also, in general, in a lithium ion secondary battery, the reaction of the electrode body (power generation element) in the case proceeds excessively due to overcharging, etc., and gas is generated and accumulated inside the case, causing the internal pressure to rise abnormally. In order to prevent this, a safety valve is provided for venting the internal gas when the internal pressure exceeds a set pressure.

JP 2009-48968 A

  In patent document 1, it aims at preventing the mixing of the foreign material into the inside of the battery when fastening the screw, and improving the sealing property of the opening by screwing the screw directly into the liquid injection hole. . Therefore, the configuration for sealing the liquid injection hole does not play the role of a safety valve.

  The present invention has been made in view of the above problems, and the purpose thereof is to allow the injection hole to be used as an electrolyte replenishment hole when the power storage device is reused, and to seal the injection hole. An object of the present invention is to provide a power storage device whose structure can serve as a safety valve.

  A power storage device that solves the above problem is a power storage device in which a hole into which an electrolytic solution can be injected is formed on an upper wall of a case in which an electrode assembly is accommodated. The hole is formed in a state in which a large-diameter portion in which a female screw portion is formed and a small-diameter portion formed in the bottom portion are continuous, and the bottom portion covers the bottom portion and does not overlap the small-diameter portion. A sealing member made of an elastic body having a gas passage hole formed therein is disposed, and a fastening member that is threadedly engaged with the female screw portion in the large-diameter portion and has a through hole formed in the axial direction includes the sealing member. A pressing force that presses against the bottom is attached to be adjustable. Here, the “upper wall of the case” means a wall disposed on the upper side in a state in which the power storage device is used, and generally a lid that covers an opening formed on the upper side of the case is the upper wall. However, in the case of the power storage device in which the electrode assembly is accommodated in the case from the opening formed on the side of the case and then the opening is sealed with the lid, there is a hole for injecting the electrolyte instead of the lid. The formed wall becomes the upper wall. In addition, the term “elastic body” means not only a material that exhibits elasticity even when it is formed as a uniform solid body such as rubber, but also a material that exhibits elasticity in a porous state such as foamed plastic. To do. In the case of foamed plastic, a closed cell foam is preferred.

  According to this configuration, after the electrolyte is injected from the small-diameter portion of the hole into which the electrolyte can be injected, the seal member is disposed at the bottom of the large-diameter portion, and the seal member is screwed with the female screw portion of the large-diameter portion. The tightening member fixed to the large diameter portion in the state is fixed in a state where the tightening force by the tightening member is adjusted. Since the seal member is made of an elastic body, when the pressure in the case becomes equal to or higher than a preset pressure due to overcharging or the like in the state of use of the power storage device, the gas in the case becomes the bottom of the large diameter portion and the contact portion of the seal member Pass between. Then, after passing through the gas passage hole of the seal member, it is discharged through the through hole of the tightening member, and the seal member serves as a safety valve. Further, since the sealing member is made of an elastic body, the sealing member performs a good sealing function when the pressure in the case is less than a preset pressure. Further, since the tightening member is screwed into the large-diameter portion of the hole, when the power storage device is reused, if the seal member is removed with the tightening member removed, the small-diameter portion of the hole is replaced with the electrolyte replenishing hole. Can be used as Therefore, according to the present invention, the injection hole can be used as an electrolyte replenishment hole when the power storage device is reused, and the injection hole sealing structure can serve as a safety valve.

  The tightening member preferably applies a pressing force to the seal member via a spring. The tightening member can also adjust the pressing force with respect to the seal member by adjusting the screwing amount with respect to the female screw portion in a state where it is in contact with the seal member. However, it is easier to adjust the pressing force to a target value by pressing the seal member via the spring.

  A hard pressing plate having a gas passage hole formed at the same position as the sealing member is disposed on the sealing member, and the sealing member receives the pressing force from the tightening member via the pressing plate. It is preferable. Here, the “hard pressing plate” is a portion that receives a pressing force directly when the pressing plate receives a pressing force partially from the other side with an elastic body arranged on one side. The other part also means a pressing plate that can move together with the part directly receiving the pressing force and press the elastic body. According to this configuration, since the sealing member receives a pressing force by the tightening member via the hard pressing plate, the pressing force by the tightening member uniformly presses the sealing member, and the sealing function of the sealing member works well. .

  According to the present invention, the liquid injection hole can be used as an electrolyte replenishment hole when the power storage device is reused, and the liquid injection hole sealing structure can serve as a safety valve.

(A) is a schematic cross section of the secondary battery of one embodiment, (b) is an enlarged cross sectional view of the sealing structure. The disassembled perspective view of a sealing structure. The schematic cross section which shows an effect | action. The partial expanded sectional view of another embodiment. The partial schematic cross section of the secondary battery of another embodiment. The schematic cross section of a prior art.

Hereinafter, an embodiment in which the present invention is embodied in a lithium ion secondary battery will be described with reference to FIGS.
As shown in FIG. 1A, in a secondary battery 10 as a power storage device, an electrode assembly 12 and an electrolytic solution 13 are accommodated in a case 11. The case 11 includes a bottomed square cylindrical case main body 14 and a lid 15 that closes an opening of the case main body 14 into which the electrode assembly 12 is inserted. The case main body 14 and the lid 15 are joined by welding. The case main body 14 and the lid body 15 are made of an aluminum-based metal.

  A positive electrode terminal 16 and a negative electrode terminal 17 are fixed to the lid 15. The positive electrode terminal 16 and the negative electrode terminal 17 have male screw portions 16 a and 17 a and flange portions 16 b and 17 b, and pass through holes formed in the lid body 15 with the flange portions 16 b and 17 b positioned inside the case 11. Then, it is fastened and fixed to the lid body 15 by a nut 18 that is screwed into the male screw portions 16a and 17a protruding from the lid body 15. The positive terminal 16 and the negative terminal 17 are configured such that a bus bar 19 that electrically connects the plurality of secondary batteries 10 can be fastened and fixed by bolts 20.

  The positive electrode terminal 16 is electrically connected to the positive electrode tab 12p of the electrode assembly 12 through a conductive member 21 bonded to the flange portion 16b. The negative electrode terminal 17 is electrically connected to the negative electrode tab 12n of the electrode assembly 12 through a conductive member 22 bonded to the flange portion 17b.

Next, a liquid injection hole for injecting the electrolytic solution 13 and a sealing structure capable of sealing the liquid injection hole and serving as a safety valve of the secondary battery 10 will be described in detail.
As shown in FIGS. 1B and 2, a hole 15 into which the electrolytic solution 13 can be injected is formed in the lid 15 as the upper wall of the case 11. The hole 30 is formed in a state in which a large-diameter portion 31 with an internal thread portion 31a formed on the upper side and a small-diameter portion 32 formed on the bottom portion 31b are continuous. The small diameter portion 32 functions as a liquid injection hole. An elastic seal member 33 having a gas passage hole 33a formed at a position that covers the bottom 31b and does not overlap the small diameter portion 32 is disposed on the bottom 31b. On the seal member 33, a hard pressing plate 34 in which a gas passage hole 34 a is formed at the same position as the seal member 33 is disposed. In this embodiment, a plurality of, for example, four gas passage holes 33a and four gas passage holes 34a are formed. The large-diameter portion 31 is formed so that the diameter of the female screw portion 31a is larger than the diameter of the portion in which the seal member 33 and the pressing plate 34 are accommodated.

  A fastening member 35 having a male screw portion 35a that is screwed with the female screw portion 31a is attached to the large-diameter portion 31 so that the pressing force for pressing the seal member 33 against the bottom portion 31b can be adjusted. The tightening member 35 is formed with a through hole 35b extending in the axial direction. On the upper surface of the tightening member 35, a key groove 35 c is formed for engaging a tool (driver) that rotates in a state where the tightening member 35 is screwed with the female screw portion 31 a of the large-diameter portion 31. The seal member 33 receives a pressing force from the tightening member 35 via the pressing plate 34. In this embodiment, the tightening member 35 applies a pressing force to the seal member 33 via the spring 36. That is, the sealing member 33, the pressing plate 34, the tightening member 35, and the spring 36 constitute a sealing structure for the liquid injection hole (small diameter portion 32). In this embodiment, a compression coil spring is used as the spring 36.

Next, the small-diameter portion (injection hole) 32 configured as described above and the small-diameter portion (injection hole) 32 are sealed, and a sealing structure that can serve as a safety valve of the secondary battery 10 The operation of will be described.
In the method for manufacturing the secondary battery 10, after the electrode assembly 12 is accommodated in the case 11, an injection step of injecting the electrolytic solution 13 from the small diameter portion (injection hole) 32, and the small diameter portion (injection after injection) Hole) 32 is temporarily sealed, and an aging step of performing aging is provided. In addition, after the aging, the temporary sealing is released and the gas generated in the aging process is released to the outside of the case 11, and then the sealing process is performed to fully seal the small diameter portion (injection hole) 32.

  In the liquid injection process, after removing the tightening member 35 screwed into the female thread portion 31a of the large diameter portion 31, the spring 36, the pressing plate 34 and the seal member 33 are taken out from the large diameter portion 31, and the small diameter portion 32 is formed. Leave it open. In this state, an electrolyte solution tank (not shown) is disposed above the case 11, and the electrolyte solution is injected into the case 11 from the small diameter portion 32.

  After the injection of the electrolytic solution is completed, the seal member 33 and the pressing plate 34 are stacked in a state where the gas passage holes 33a and 34a overlap with each other, and the seal member 33 is accommodated in the large-diameter portion 31 in a state where the seal member 33 is in contact with the bottom 31b. Next, the spring 36 is placed on the pressing plate 34, and in this state, the tightening member 35 is screwed into the female screw portion 31a, and the spring 36 is rotated until the screwing amount reaches a preset value.

  As shown in FIG. 3, when the tightening member 35 is fixed at a position where the screwing amount is set in advance, the seal member 33 is in a state where the tightening force by the tightening member 35 is adjusted to a preset value. Fixed. The adjusted state means a state in which the gas in the case 11 is discharged out of the case 11 when the pressure in the case 11 becomes equal to or higher than a preset pressure due to overcharge in the usage state of the secondary battery 10. To do. More specifically, when the pressure in the case 11 becomes equal to or higher than a preset pressure, the gas in the case 11 flows from the small diameter portion 32 to the bottom portion 31b of the large diameter portion 31 and the seal member 33 as shown by arrows in FIG. After passing between the contact portions and passing through the gas passage holes 33a and 34a, the gas is discharged through the through hole 35b of the tightening member 35. Therefore, the seal member 33 serves as a safety valve.

  Further, unlike the case where the sealing plug is fixed to the lid by welding, the small diameter portion 32 is used as an electrolyte replenishing hole without removing the lid 15 when the secondary battery 10 is reused (when reused). be able to.

According to this embodiment, the following effects can be obtained.
(1) The secondary battery 10 is a power storage device in which a hole 30 into which the electrolytic solution 13 can be injected is formed in the lid (upper wall) 15 of the case 11 in which the electrode assembly 12 is accommodated. The hole 30 is formed in a state in which the large-diameter portion 31 in which the female screw portion 31a is formed and the small-diameter portion 32 formed in the bottom portion 31b are continuous. The bottom portion 31b covers the bottom portion 31b and the small-diameter portion 32. An elastic seal member 33 in which a gas passage hole 33a is formed is disposed at a position that does not overlap with the gas. A fastening member 35 that is screwed into the female screw portion 31a and has a through hole 35b formed in the axial direction is attached to the large-diameter portion 31 so that the pressing force for pressing the seal member 33 against the bottom portion 31b can be adjusted.

  According to this configuration, after the electrolyte solution 13 is injected into the case 11 from the small diameter portion 32 of the hole 30 into which the electrolyte solution 13 can be injected, the seal member 33 is disposed on the bottom portion 31 b of the large diameter portion 31. The seal member 33 is fixed in a state in which the tightening force by the tightening member 35 is adjusted by the tightening member 35 fixed to the large diameter portion 31 in a state of being screwed with the female screw portion 31a of the large diameter portion 31. Since the seal member 33 is made of an elastic material, when the pressure in the case 11 becomes equal to or higher than a preset pressure due to overcharge or the like in the usage state of the secondary battery 10, the gas in the case 11 passes through the small diameter portion 32 and becomes large. It passes between the bottom part 31 b of the diameter part 31 and the contact part of the seal member 33. Then, after passing through the gas passage hole 33a of the seal member 33 and the gas passage hole 34a of the holding plate 34, the seal member 33 is discharged through the through hole 35b of the tightening member 35, so that the seal member 33 serves as a safety valve.

  Further, since the seal member 33 is made of an elastic body, the seal member 33 performs a good sealing function when the pressure in the case 11 is less than a preset pressure. Further, since the tightening member 35 is screwed into the large-diameter portion 31 of the hole 30, when the secondary battery 10 is reused, the seal member 33 can be removed after removing the tightening member 35 and the pressing plate 34. For example, the small diameter portion 32 of the hole 30 can be used as an electrolyte solution replenishing hole. Therefore, the small diameter portion (injection hole) 32 can be used as an electrolyte replenishment hole when the secondary battery (power storage device) 10 is reused, and the sealing structure of the injection hole (small diameter portion 32) is a safety valve. Can play a role.

  (2) The tightening member 35 applies a pressing force to the seal member 33 via the spring 36 and the pressing plate 34. The tightening member 35 can also adjust the pressing force against the seal member 33 by adjusting the screwing amount with respect to the female screw portion 31a in a state where the tightening member 35 is in contact with the seal member 33 without passing through the spring 36 and the pressing plate 34. However, it is easier to adjust the pressing force to a target value by pressing the seal member 33 via the spring 36 and the pressing plate 34.

  (3) On the seal member 33, a hard pressing plate 34 in which a gas passage hole 34 a is formed at the same position as the gas passage hole 33 a of the sealing member 33 is disposed, and the sealing member 33 is interposed via the pressing plate 34. Then, a pressing force is received from the tightening member 35. According to this configuration, since the sealing member 33 receives a pressing force by the tightening member 35 via the hard pressing plate 34, the pressing force by the tightening member 35 uniformly presses the sealing member 33, and the sealing member 33 seals. The function works well.

  (4) On the upper surface of the tightening member 35, a keyway 35c is formed for hooking a tool for rotating the tightening member 35 in a state where the tightening member 35 is screwed with the female screw portion 31a of the large diameter portion 31. Yes. Therefore, the adjustment of the pressing force by the tightening member 35 applied to the seal member 33 is facilitated from the extending direction of the key groove 35c and the amount of rotation when the tightening member 35 is screwed into the female screw portion 31a.

The embodiment is not limited to the above, and may be embodied as follows, for example.
As shown in FIG. 4, the lid body 15 is not formed to have a constant thickness, but is formed in a state in which a portion where a liquid injection hole (small-diameter portion 32) and a portion constituting the sealing structure are provided protrudes. May be. In this case, it is not necessary to form the entire lid 15 thick, which contributes to weight reduction.

  The tightening member 35 is not limited to a screw having a key groove 35c for hooking a tool for rotating the tightening member 35 on the upper surface, and a bolt may be used. However, the screw having the keyway 35c formed on the upper surface can reduce the thickness of the lid 15.

  The tightening member 35 is not limited to a structure that applies a pressing force to the seal member 33 via the spring 36 and the pressing plate 34, and the screwing amount with respect to the female screw portion 31a in a state in which the tightening member 35 is in direct contact with the pressing plate 34. You may make it adjust the pressing force with respect to the sealing member 33 by adjusting. However, the configuration in which the seal member 33 is pressed via the spring 36 and the pressing plate 34 makes it easier to adjust the pressing force to a target value.

  The spring 36 is not limited to a compression coil spring, and for example, a bamboo child spring or a leaf spring may be used. However, the compression coil spring can easily apply a pressing force to the seal member 33.

  O It is good also as a structure which the spring 36 presses directly the sealing member 33, without arrange | positioning the hard pressing board 34 in which the gas passage hole 34a was formed in the same position as the sealing member 33 on the sealing member 33. FIG. However, the configuration in which the spring 36 applies a pressing force to the seal member 33 via the hard pressing plate 34 is more than the configuration in which the spring 36 directly contacts the seal member 33 and presses the seal member 33. The pressing force by 35 presses the sealing member 33 uniformly, and the sealing function of the sealing member 33 works well.

  The sealing member 33 and the pressing plate 34 may be used as parts that are integrally joined and fixed in advance. In this case, the number of parts constituting the sealing structure of the liquid injection hole (small diameter part 32) is reduced, and after injecting the electrolytic solution 13 from the small diameter part 32, there is an effort to seal the liquid injection hole (small diameter part 32). Less.

  As shown in FIG. 5, the case 11 may be composed of a case main body 14 whose front side is open and a lid 15 that covers the opening. In this case, the hole 30 into which the electrolytic solution 13 can be injected is formed not in the lid body 15 but in the upper wall 11a of the case 11.

The large diameter portion 31 may be formed so that the diameter of the female screw portion 31a is the same as the diameter of the portion in which the seal member 33 and the pressing plate 34 are accommodated.
The present invention is not limited to the stacked electrode assembly 12 and may be applied to the secondary battery 10 having a wound electrode assembly.

  ○ The positive electrode terminal 16 and the positive electrode conductive member 21 or the negative electrode terminal 17 and the negative electrode conductive member 22 are not limited to the structure in which the separately formed members are later fixed together by welding or an adhesive, etc. The formed structure may be used.

The secondary battery 10 is not limited to a lithium ion secondary battery, and may be another secondary battery such as a nickel hydrogen secondary battery or a nickel cadmium secondary battery.
The power storage device is not limited to the secondary battery 10 and may be a capacitor such as an electric double layer capacitor or a lithium ion capacitor.

  DESCRIPTION OF SYMBOLS 10 ... Secondary battery as a power storage device, 11 ... Case, 11a ... Upper wall, 12 ... Electrode assembly, 13 ... Electrolyte, 15 ... Lid as upper wall, 30 ... Hole, 31 ... Large diameter part, 31a ... female screw part, 31b ... bottom part, 32 ... small diameter part, 33 ... sealing member, 33a, 34a ... gas passage hole, 34 ... pressing plate, 35 ... tightening member, 35b ... through hole, 36 ... spring.

Claims (3)

A power storage device in which a hole into which an electrolytic solution can be injected is formed on an upper wall of a case in which an electrode assembly is accommodated,
The hole is formed in a state in which a large-diameter portion in which an internal thread portion is formed and a small-diameter portion formed in the bottom portion are continuous, and the bottom portion covers the bottom portion and gas does not overlap the small-diameter portion. A sealing member made of an elastic body having a passage hole is disposed, and a tightening member that is threadedly engaged with the female screw portion in the large diameter portion and has a through hole formed in the axial direction, the sealing member is connected to the bottom portion. The power storage device is characterized in that the pressing force for pressing is attached to be adjustable.   The power storage device according to claim 1, wherein the tightening member applies a pressing force to the seal member via a spring.   A hard pressing plate having a gas passage hole formed at the same position as the sealing member is disposed on the sealing member, and the sealing member receives the pressing force from the tightening member via the pressing plate. The power storage device according to claim 1.

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