JP2018049737A - Power storage device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power storage device capable of suppressing a part of an electrode from scattering from a pressure release valve having been cleaved in a nail penetration test, and also preventing metal powder as a part of a case from scattering from the pressure release valve having been cleaved.SOLUTION: A secondary battery 10 comprises a coating part 64 interposed between an inner surface 14a of a lid body 14 and a shield part 61. The coating part 64 has a through hole 65 opposed to a pressure release valve 18. A region of the coating part 64 at a periphery of a through hole 65 covers a region on the inner surface 14a of the lid body 14 at a periphery of the pressure release valve 18. A high-pressure gas produced at a short-circuit part collides against the shield part 61 in flowing toward the pressure release valve 18 having been cleaved to change its flow direction, so that a path of the gas flowing toward the pressure release valve 18 becomes long. Thus, the gas to flow toward the pressure release valve 18 after colliding against the shield part 61 is prevented from colliding against the region on the inner surface 14a of the lid body 14 at the periphery of the pressure release valve 18 before being discharged to outside the case 11 from the pressure release valve 18.SELECTED DRAWING: Figure 6

Description

  The present invention relates to a power storage device including a pressure release valve.

  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. For example, as described in Patent Document 1, the secondary battery includes an electrode assembly and an electrolytic solution housed in a metal case, and the case wall portion releases the pressure inside the case to the outside of the case. A pressure relief valve is provided.

  In such a secondary battery, when a nail penetration test that is one of the evaluation tests is performed, the nail breaks the separator between the positive electrode and the negative electrode, and the positive electrode and the negative electrode are in the case. Short circuit. When a short circuit occurs, heat is generated around the short circuit part, the electrolyte component is decomposed by the heat generated around the short circuit part, and gas is generated in the case. Then, the pressure in the case rises and the pressure release valve is opened, but when the gas is released from the pressure release valve to the outside of the case, a part of the electrode is scraped off by the high pressure gas, and it gets on the gas as it is. There is a risk of splashing outside.

  Therefore, Patent Document 1 discloses a secondary battery including a safety protection device having a baffle plate (shielding portion) facing a pressure relief valve (pressure release valve). When the pressure in the case rises and the pressure relief valve is cleaved, the high-pressure gas generated at the short-circuit portion collides with the baffle plate on the way to the pressure relief valve, and the direction of gas flow changes. Then, since the gas path toward the pressure release valve becomes longer, it is possible to prevent a part of the electrode from riding on the gas and scattering to the outside of the case.

Japanese Patent Laid-Open No. 2006-96129

  However, as in Patent Document 1, before the gas directed to the pressure relief valve after colliding with the baffle plate is released from the pressure relief valve to the outside of the case, the portion around the pressure relief valve on the inner surface of the wall portion of the case It is easy to collide with. When the gas collides with the inner surface of the case wall, the gas colliding part on the inner surface of the case wall is scraped off to generate metal powder, and the metal powder may get on the gas as it is and splash outside the case. is there.

  The present invention has been made in order to solve the above-mentioned problems, and its purpose is to suppress a part of the electrode from scattering from the cleaved pressure relief valve during the nail penetration test and to cleave the pressure relief. An object of the present invention is to provide a power storage device that can prevent metal powder that is a part of a case from scattering from a valve.

  An electricity storage device that solves the above problems includes an electrode assembly in which electrodes of different polarities are insulated from each other and having a layered structure, an electrolytic solution, a metal case that contains the electrode assembly and the electrolytic solution, A pressure release valve that is present in the wall portion of the case and is cleaved when the pressure in the case reaches an open pressure, and releases the pressure in the case to the outside of the case; an inner surface of the wall portion; A power storage device having a shielding portion interposed between the opposing end surfaces of the electrode assembly and facing the pressure release valve, wherein the covering is interposed between the inner surface of the wall portion and the shielding portion The covering portion has a through hole facing the pressure release valve, and the portion around the through hole in the covering portion is a portion around the pressure release valve on the inner surface of the wall portion. Covering.

  According to this, during the nail penetration test, the high-pressure gas generated in the short-circuited part where the electrodes of different polarities are short-circuited via the nail is on the way to the pressure release valve that has been opened when the pressure in the case reaches the release pressure. By colliding with the shield and changing the direction of gas flow, the gas path toward the pressure release valve becomes longer. As a result, a part of the electrode contained in the gas is prevented from falling from the gas in the case, and a part of the electrode is prevented from scattering from the cleaved pressure release valve to the outside of the case.

  The high-pressure gas generated in the short-circuit part collides with the shielding part on the way to the pressure release valve and changes the direction of the gas flow, and then flows again toward the pressure release valve, through the through hole of the covering part. Released from the pressure relief valve. Here, since the site | part surrounding the through-hole in a coating | coated part has covered the site | part surrounding the pressure release valve in the inner surface of a wall part, the gas which goes to a pressure release valve after colliding with a shielding part is from a pressure release valve. It is possible to avoid colliding with a portion around the pressure release valve on the inner surface of the wall portion before being discharged out of the case. As a result, the gas around the pressure relief valve on the inner surface of the wall can be prevented from being scraped by the gas going to the pressure relief valve, and the generation of metal powder can be prevented. Scattering outside is suppressed.

  The power storage device includes a shielding member that exists in a state in which different polarities are not short-circuited between an inner surface of the wall portion and an end surface of the electrode assembly facing the inner surface, and the shielding member includes the shielding portion and It is good to have the said covering part integrally and to have an opening part between the said shielding part and the said covering part. According to this, compared with the case where a shielding part and a coating | coated part are separate bodies, a number of parts can be reduced and a structure can be simplified. Moreover, the gas which goes to a pressure relief valve collides with a shielding part, the direction of a gas flow changes, and is discharged | emitted out of a case from a pressure relief valve through the opening part of a shielding member, and the through-hole of a coating | coated part.

  In the above power storage device, a tab group having a shape protruding from a part of one side of the electrode is bonded to the tab group, and is interposed between the wall portion and the tab group. A conductive member and an insulating cover that insulates the wall portion and the conductive member may be provided, and the insulating cover may function as the covering portion. According to this, by making the insulating cover which is an existing member function as the covering portion, it is not necessary to separately prepare the covering portion as a separate member, so that the number of parts can be reduced.

  In the above power storage device, the power storage device may be a secondary battery.

  According to the present invention, at the time of a nail penetration test, a part of the electrode is prevented from scattering from the cleaved pressure release valve, and a metal powder which is a part of the case is prevented from scattering from the cleaved pressure release valve. it can.

The disassembled perspective view of the secondary battery in embodiment. The perspective view of a secondary battery. The disassembled perspective view which shows the component of an electrode assembly. The cross-sectional view of a secondary battery. The sectional side view of a secondary battery. The longitudinal cross-sectional view which shows the state which the valve body of the pressure release valve opened. The disassembled perspective view of the secondary battery in another embodiment. The sectional side view of a secondary battery.

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, the secondary battery 10 as the power storage device includes a metal case 11 made of, for example, aluminum. The secondary battery 10 includes an electrode assembly 12 accommodated in a case 11 and an electrolytic solution. The case 11 includes a case main body 13 having an opening 13 a and a lid body 14 that closes the opening 13 a of the case main body 13.

  The case body 13 includes a rectangular plate-shaped bottom wall 13b, a short side wall 13c that protrudes from both short side edges of the bottom wall 13b, and a long side wall 13d that protrudes from both long side edges of the bottom wall 13b. With. The case 11 has a rectangular parallelepiped shape, and the electrode assembly 12 has a rectangular parallelepiped shape according to the case 11. The secondary battery 10 is a square lithium ion secondary battery.

  As shown in FIG. 3, the electrode assembly 12 includes a plurality of positive electrodes 21 having a rectangular sheet shape and a plurality of negative electrodes 31 having a rectangular sheet shape. The positive electrode 21 and the negative electrode 31 are electrodes having different polarities. The positive electrode 21 includes a positive metal foil 21a and a positive electrode active material layer 21b present on both surfaces of the positive metal foil 21a. The positive electrode metal foil 21a is, for example, an aluminum foil. The negative electrode 31 includes a negative electrode metal foil 31a and negative electrode active material layers 31b present on both surfaces of the negative electrode metal foil 31a. The negative electrode metal foil 31a is, for example, a copper foil. The electrode assembly 12 is a laminated type having a layered structure in which separators 24 are interposed between a plurality of positive electrodes 21 and a plurality of negative electrodes 31. The separator 24 insulates the positive electrode 21 and the negative electrode 31. That is, the electrode assembly 12 has a layered structure in which the positive electrode 21 and the negative electrode 31, which are electrodes of different polarities, are insulated from each other by the separator 24. In addition, the stacking direction of the electrode assembly 12 is the short direction of the lid 14 in the case 11.

  As shown in FIG. 1, the positive electrode 21 has a tab 25 having a shape protruding from a part of one side of the positive electrode 21. The negative electrode 31 has a tab 35 having a shape protruding from a part of one side of the negative electrode 31. The plurality of positive electrode tabs 25 and the plurality of negative electrode tabs 35 are arranged at positions shifted from each other in the longitudinal direction of the lid body 14 in a state where the positive electrode 21 and the negative electrode 31 are stacked. Therefore, the plurality of positive electrode tabs 25 and the plurality of negative electrode tabs 35 do not overlap each other in a state where the positive electrode 21 and the negative electrode 31 are laminated. The electrode assembly 12 has a tab-side end face 12b from which the tabs 25 and 35 protrude. The tab-side end surface 12 b is an end surface of the electrode assembly 12 that faces the inner surface 14 a of the lid body 14.

  The secondary battery 10 includes a positive electrode tab group 26 having a shape protruding from the tab-side end surface 12b. The positive electrode tab group 26 is configured by collecting and stacking all the positive electrode tabs 25 having the same polarity on one end side in the stacking direction of the electrode assembly 12. The secondary battery 10 includes a negative electrode tab group 36 having a shape protruding from the tab-side end surface 12b. The negative electrode tab group 36 is formed by stacking all the negative electrode tabs 35 having the same polarity together at one end side in the stacking direction of the electrode assembly 12.

  The secondary battery 10 includes a positive electrode conductive member 41 that is a conductive member. The positive electrode conductive member 41 has a rectangular plate shape with the length extending in the longitudinal direction of the lid body 14. A positive electrode tab group 26 is joined to one end in the longitudinal direction of the positive electrode conductive member 41. One end side in the longitudinal direction of the positive electrode conductive member 41 is interposed between the inner surface 14a of the lid body 14 and the tab group 26 of the positive electrode. The other part of the positive electrode conductive member 41 is disposed between the inner surface 14a of the lid 14 and the tab side end surface 12b of the electrode assembly 12 facing the inner surface 14a. A positive electrode terminal 42 is joined to the other end in the longitudinal direction of the positive electrode conductive member 41. The positive electrode terminal 42 extends from the positive electrode conductive member 41 toward the side opposite to the electrode assembly 12 (the lid body 14 side).

  The secondary battery 10 includes a negative electrode conductive member 51 that is a conductive member. The negative electrode conductive member 51 is in the shape of a rectangular plate whose length extends in the longitudinal direction of the lid body 14. A negative electrode tab group 36 is joined to one end side in the longitudinal direction of the negative electrode conductive member 51. One end side in the longitudinal direction of the negative electrode conductive member 51 is interposed between the inner surface 14a of the lid body 14 and the tab group 36 of the negative electrode. The other part of the negative electrode conductive member 51 is disposed between the inner surface 14a of the lid body 14 and the tab side end surface 12b of the electrode assembly 12 facing the inner surface 14a. A negative electrode terminal 52 is joined to the other end side in the longitudinal direction of the negative electrode conductive member 51. The negative electrode terminal 52 extends from the negative electrode conductive member 51 toward the side opposite to the electrode assembly 12 (the lid body 14). The positive terminal 42 and the negative terminal 52 extend in parallel to each other.

  The positive electrode conductive member 41 and the negative electrode conductive member 51 are separated from each other in the longitudinal direction of the lid body 14. The positive electrode terminal 42 and the negative electrode terminal 52 pass through the lid body 14 and a part thereof is exposed outside the case 11. In addition, ring-shaped insulating members 17 a for insulating from the case 11 are attached to the positive terminal 42 and the negative terminal 52, respectively.

  The secondary battery 10 has a pressure release valve 18 present in the lid 14 that is a wall portion of the case 11. The pressure release valve 18 is opened when the pressure in the case 11 reaches an open pressure that is a predetermined pressure, and releases the pressure in the case 11 to the outside of the case 11. The release pressure of the pressure release valve 18 is set to a pressure at which the case 11 itself or the joint portion between the case body 13 and the lid body 14 can be broken before a crack or breakage can occur.

  In the present embodiment, the pressure release valve 18 is formed integrally with the lid body 14. Specifically, a concave portion 20 is formed on the outer surface 14 b located on the outer side of the case 11 out of both surfaces of the lid body 14, and the pressure release valve 18 is a plate-like portion that forms the bottom portion of the concave portion 20. It is. Therefore, the thickness of the pressure release valve 18 is thinner than the thickness of the portion other than the pressure release valve 18 in the lid body 14.

  The recess 20 is located closer to the positive electrode terminal 42 than the center in the longitudinal direction of the lid body 14. Therefore, the pressure release valve 18 is located closer to the positive electrode terminal 42 than the center in the longitudinal direction of the lid body 14. The recess 20 is located at the center of the lid 14 in the short direction. Therefore, the pressure release valve 18 is located at the center of the lid 14 in the short direction. The recess 20 has a long hole shape extending in the longitudinal direction of the lid body 14 when the outer surface 14b of the lid body 14 is viewed in plan. Therefore, the pressure release valve 18 has an oval shape whose longitudinal direction extends in the longitudinal direction of the lid body 14 when the outer surface 14b of the lid body 14 is viewed in plan view.

  As shown in FIG. 1, FIG. 4 or FIG. 5, the secondary battery 10 includes a shielding member 60. The shielding member 60 is disposed between the positive electrode conductive member 41 and the negative electrode conductive member 51 in the longitudinal direction of the lid body 14. The shielding member 60 is disposed between the inner surface 14a of the lid body 14 and the tab side end surface 12b, and is placed on the tab side end surface 12b. The shielding member 60 is made of synthetic resin. For this reason, the shielding member 60 does not short-circuit the positive potential member and the negative potential member in the case 11. That is, the shielding member 60 exists in the state which does not short-circuit a different polarity between the inner surface 14a of the cover body 14 and the tab side end surface 12b.

  The shielding member 60 of the present embodiment has a rectangular parallelepiped shape (square box shape) having an opening 60a on the surface on the negative electrode conductive member 51 side. And the inside of the shielding member 60 and the inside of the case 11 are connected via the opening part 60a.

  The shielding member 60 includes a rectangular plate-shaped shielding part 61. The shielding part 61 is interposed between the inner surface 14 a of the lid body 14 and the tab side end face 12 b and faces the pressure release valve 18 in the thickness direction of the lid body 14. The longitudinal direction of the shielding part 61 extends in the longitudinal direction of the lid body 14. The shielding member 60 includes a first wall portion 62 having a shape erected from the pair of long edge portions of the shielding portion 61 toward the lid body 14. The first wall portion 62 has a shape that extends in the longitudinal direction of the lid body 14. The shielding member 60 includes a second wall portion 63. The second wall portion 63 has a shape erected from the short edge portion near the positive electrode conductive member 41 toward the lid body 14 among the pair of short edge portions of the shielding portion 61. A pair of 1st wall part 62 and the 2nd wall part 63 are mutually connected.

  The shielding member 60 has a rectangular plate-shaped covering portion 64 facing the shielding portion 61. Therefore, in this embodiment, the shielding member 60 integrally includes the shielding part 61 and the covering part 64, and has an opening 60 a between the shielding part 61 and the covering part 64. The covering portion 64 is interposed between the inner surface 14 a of the lid body 14 and the shielding portion 61. The length of the covering portion 64 extends in the longitudinal direction of the lid body 14. A pair of long edge portions of the covering portion 64 are connected to the first wall portions 62. Of the pair of short edges of the covering part 64, the short edge near the positive electrode conductive member 41 is connected to the second wall part 63. The outer surface 64 a of the covering portion 64 is disposed to face the inner surface 14 a of the lid body 14.

  The outer surface of the second wall 63 can contact one end surface of the positive electrode conductive member 41 in the longitudinal direction. Further, the outer surface of the second wall portion 63 and the end surface of the shielding portion 61 can contact the side surface of the tab group 26 of the positive electrode. Similarly, the end surface of the shielding part 61 can contact the side surface of the tab group 36 of the negative electrode. When the shielding member 60 moves slightly in the longitudinal direction of the lid body 14, it quickly contacts the positive electrode conductive member 41, the positive electrode tab group 26, or the negative electrode tab group 36. For this reason, as for the shielding member 60, the movement to the longitudinal direction of the cover body 14 is controlled.

  The outer surface of one first wall 62 can contact the inner surface of one long side wall 13d of the case body 13, and the outer surface of the other first wall 62 can contact the inner surface of the other long side wall 13d. Is possible. The shielding member 60 is in a state of being separated from the inner surface of each long side wall 13 d that is the inner surface of the case 11. When the shielding member 60 moves slightly in the short direction of the lid body 14, it quickly comes into contact with any of the long side walls 13 d. For this reason, as for the shielding member 60, the movement to the transversal direction of the cover body 14 is controlled. Therefore, the movement of the shielding member 60 in any direction along the tab-side end surface 12b is restricted.

  The covering portion 64 has a through hole 65 that faces the pressure release valve 18 in the thickness direction of the lid body 14. The through-hole 65 has a long hole shape extending in the longitudinal direction of the lid body 14 when the outer surface 64a of the covering portion 64 is viewed in plan.

  As shown in FIG. 4, the length L1 in the longitudinal direction of the through hole 65 is shorter than the length L11 in the longitudinal direction of the pressure release valve 18 (recess 20). The length L2 in the short direction of the through-hole 65 is shorter than the length L12 in the short direction of the pressure release valve 18 (recess 20). The through hole 65 is a hole that is smaller than the recess 20 in a plan view. In the thickness direction of the lid body 14, the entire region of the through hole 65 overlaps the pressure release valve 18 (recessed portion 20).

  As shown in FIG. 5, the inner peripheral surface 65 a of the covering portion 64 that forms the through hole 65 overlaps the pressure release valve 18 in the thickness direction of the lid body 14. And the site | part around the through-hole 65 in the coating | coated part 64 has overlapped with the site | part surrounding the pressure release valve 18 in the inner surface 14a of the cover body 14 in the thickness direction of the cover body 14, and also the pressure release valve 18. It also overlaps the outer edge of the. Therefore, the site | part around the through-hole 65 in the coating | coated part 64 has covered the site | part surrounding the pressure release valve 18 in the inner surface 14a of the cover body 14. FIG. In addition, it is preferable to form the site | part around the through-hole 65 in the coating | coated part 64 with a resin with good heat resistance, or to provide a coat layer with good heat resistance in the site | part around the through-hole 65 in the coating | coated part 64.

  When the site around the pressure release valve 18 on the inner surface 14a of the lid 14 is not covered by the site around the through hole 65 in the covering portion 64, the gas directed to the pressure release valve 18 is transferred from the pressure release valve 18 to the case. 11 is a portion that is likely to collide before being released to the outside. Therefore, in the present embodiment, the portion around the through hole 65 in the covering portion 64 is a lid that is a portion where the gas toward the pressure release valve 18 easily collides before being released from the pressure release valve 18 to the outside of the case 11. At least a portion around the pressure release valve 18 on the inner surface 14a of the body 14 is covered.

Next, the operation of this embodiment will be described.
In such a secondary battery 10, when a nail penetration test, which is one of the evaluation tests, is performed, the nail penetrates the electrode assembly 12 in the stacking direction, and the nail is interposed between the positive electrode 21 and the negative electrode 31. The separator 24 is broken, and the positive electrode 21 and the negative electrode 31 are short-circuited in the case 11. When a short circuit occurs, heat is generated in the vicinity of the short circuit part, the electrolyte component is decomposed by the heat generated in the vicinity of the short circuit part, and gas is generated in the case 11. Then, the pressure in the case 11 rises.

  As shown in FIG. 6, when the pressure in the case 11 rises and the pressure in the case 11 reaches the opening pressure of the pressure releasing valve 18, the pressure releasing valve 18 is cleaved. Then, the gas generated in the short-circuit portion flows toward the pressure release valve 18 that has been cleaved as indicated by an arrow in FIG. Moreover, a part of each electrode 21 and 31 is stripped off by the generated gas. The gas which goes to the pressure release valve 18 collides with the outer surface 61a of the shielding part 61, and the direction of the gas flow changes. The gas whose direction of flow has changed due to the collision with the shielding part 61 flows into the shielding member 60 through the opening 60a of the shielding member 60, and from the pressure release valve 18 to the outside of the case 11 through the through hole 65. Is released.

In the above embodiment, the following effects can be obtained.
(1) The high-pressure gas generated in the short-circuit portion collides with the shielding portion 61 on the way to the pressure release valve 18 that has been opened due to the pressure in the case 11 reaching the release pressure, and the direction of the gas flow is changed. The gas path toward the pressure release valve 18 becomes longer. As a result, a part of the electrodes 21, 31 contained in the gas is prevented from falling from the gas in the case 11, and a part of the electrodes 21, 31 is prevented from scattering out of the case 11 from the cleaved pressure release valve 18. It can be deterred from sparking. Further, a portion around the through hole 65 in the covering portion 64 covers a portion around the pressure release valve 18 on the inner surface 14 a of the lid body 14. For this reason, before the gas which goes to the pressure release valve 18 after colliding with the shielding part 61 is discharge | released out of the case 11 from the pressure release valve 18, it is in the site | part around the pressure release valve 18 in the inner surface 14a of the cover body 14. A collision can be avoided. As a result, the gas surrounding the pressure release valve 18 on the inner surface 14a of the lid body 14 can be prevented from being scraped by the gas directed to the pressure release valve 18, and the generation of metal powder can be suppressed. The metal powder can be prevented from scattering out of the case 11.

  (2) The shielding member 60 integrally includes the shielding part 61 and the covering part 64, and has an opening 60 a between the shielding part 61 and the covering part 64. According to this, compared with the case where the shielding part 61 and the coating | coated part 64 are separate bodies, a number of parts can be reduced and the structure of the secondary battery 10 can be simplified. Further, the secondary battery 10 can be easily assembled. Further, the gas directed to the pressure release valve 18 collides with the shielding part 61, the direction of the gas flow is changed, and from the pressure relief valve 18 through the opening 60 a of the shielding member 60 and the through hole 65 of the covering part 64. It is discharged out of the case 11.

  (3) In the thickness direction of the lid body 14, the inner peripheral surface 65 a of the covering portion 64 that forms the through hole 65 overlaps the pressure release valve 18. And the site | part around the through-hole 65 in the coating | coated part 64 has overlapped with the site | part surrounding the pressure release valve 18 in the inner surface 14a of the cover body 14 in the thickness direction of the cover body 14, and also the pressure release valve 18. It also overlaps the outer edge of the. Therefore, for example, when the inner peripheral surface 65 a of the covering portion 64 that forms the through hole 65 overlaps the inner peripheral surface of the recess 20 in the thickness direction of the lid body 14 and does not overlap the pressure release valve 18. In comparison, the portion around the through hole 65 in the covering portion 64 can be reliably overlapped with the portion around the pressure release valve 18 of the lid body 14. Therefore, the site | part around the pressure release valve 18 in the inner surface 14a of the cover body 14 can be reliably covered with the site | part around the through-hole 65 in the coating | coated part 64. FIG.

In addition, you may change the said embodiment as follows.
As shown in FIGS. 7 and 8, the secondary battery 10 includes an insulating cover 71 that insulates the lid body 14 from the positive electrode conductive member 41 and the negative electrode conductive member 51, and the insulating cover 71 includes a through hole 65. You may make it function also as a coating | coated part. Therefore, the shielding member 60 does not have the covering portion 64 integrally, and may be a box shape with the lid body 14 opened. As described above, when the insulating cover 71 is caused to function as a covering portion, a portion around the through hole 65 in the insulating cover 71 is formed of a resin having good heat resistance, or a portion around the through hole 65 in the insulating cover 71 is heat resistant. It is preferable to provide a coat layer with good properties. The insulating cover 71 is an existing member in the secondary battery 10. According to this, by making the insulating cover 71 which is an existing member function as a covering portion, it is not necessary to separately prepare the covering portion as a separate member, so that the number of parts can be reduced.

In the embodiment, the length L1 in the longitudinal direction of the through-hole 65 and the length L11 in the longitudinal direction of the pressure release valve 18 (recess 20) may be the same.
In the embodiment, the length L2 in the short direction of the through-hole 65 and the length L12 in the short direction of the pressure release valve 18 (recess 20) may be the same.

  In the embodiment, the length L1 in the longitudinal direction of the through hole 65 is the same as the length L11 in the longitudinal direction of the pressure release valve 18 (recess 20), and the length L2 in the short direction of the through hole 65 is The length L12 in the short direction of the pressure release valve 18 (recess 20) may be the same. That is, the inner peripheral surface 65 a of the covering portion 64 that forms the through hole 65 overlaps the inner peripheral surface of the recess 20 in the thickness direction of the lid body 14, and does not have to overlap the pressure release valve 18.

The recess 20 may have a perfect circular hole shape in plan view, and the pressure release valve 18 may have a perfect circular shape in plan view. The through hole 65 may also be a perfect circular hole in plan view.
The pressure release valve 18 may be a separate member from the lid body 14. In this case, a pressure relief hole is formed in the lid body 14, and the pressure release valve 18 is attached in a sealed state with respect to the pressure relief hole.

  ○ The shielding member 60 may be made of metal. In this case, an insulating member is interposed between the positive potential member (the positive electrode conductive member 41 and the positive electrode 21) and the negative potential member (the negative electrode conductive member 51 and the negative electrode 31). The insulating member may be integrated with one of the charged member and the shielding member 60, or may be integrated with both. The insulating member may be an insulating resin or ceramic coating. Alternatively, when the shielding member 60 is made of metal, the shielding member 60 is any of a positive potential member (the positive electrode conductive member 41 and the positive electrode 21) and a negative potential member (the negative electrode conductive member 51 and the negative electrode 31). When contacting one of them, it arrange | positions in the state which does not contact the other.

The shielding member 60 may not be placed on the tab-side end surface 12b but may be joined to the inner surface 14a of the lid body 14 or other members.
O The shielding member 60 should just exist in the state which does not short-circuit a different polarity between the inner surface 14a of the cover body 14 and the tab side end surface 12b, and the structure and shape are not specifically limited.

In the embodiment, the shielding part 61 may be a separate member from the shielding member 60.
The separator 24 may not be a type in which the separator 24 is interposed between the positive electrode 21 and the negative electrode 31 one by one. For example, the separator 24 may be a bag-like separator that accommodates the positive electrode 21. Alternatively, the separator may have a long shape and may be a type that is interposed between the positive electrode 21 and the negative electrode 31 by being folded.

The electrode assembly may be a wound type in which one belt-like positive electrode and one belt-like negative electrode are wound around a winding shaft in a state where they are insulated by a separator.
The power storage device may be another power storage device such as an electric double layer capacitor.

  In embodiment, although the secondary battery 10 was a lithium ion secondary battery, it is not restricted to this, Other secondary batteries, such as nickel hydride, may be sufficient. In short, any ion may be used as long as ions move between the positive electrode active material layer and the negative electrode active material layer and transfer charge.

  DESCRIPTION OF SYMBOLS 10 ... Secondary battery as a power storage device, 11 ... Case, 12 ... Electrode assembly, 12b ... End surface on the tab side as an end surface, 14 ... Lid body as a wall, 14a ... Inner surface, 18 ... Pressure release valve, 21 ... Positive electrode as electrode, 25, 35 ... tab, 26, 36 ... tab group, 31 ... negative electrode as electrode, 41 ... positive electrode conductive member as conductive member, 51 ... negative electrode conductive member as conductive member, 60 ... shielding 60a ... opening, 61 ... shielding part, 64 ... covering part, 65 ... through hole, 71 ... insulating cover.

Claims (4)

An electrode assembly in which electrodes of different polarities are insulated from each other and having a layered structure;
An electrolyte,
A metal case containing the electrode assembly and the electrolyte;
A pressure release valve that is present in the wall of the case and is cleaved when the pressure in the case reaches an open pressure, and releases the pressure in the case to the outside of the case;
A power storage device having a shielding portion interposed between an inner surface of the wall portion and an end surface of the electrode assembly facing the inner surface, and facing the pressure release valve,
A covering portion interposed between the inner surface of the wall portion and the shielding portion;
The covering portion has a through hole facing the pressure release valve,
The part around the through-hole in the covering part covers the part around the pressure release valve on the inner surface of the wall part. A shielding member present in a state in which different polarities are not short-circuited between the inner surface of the wall portion and the end surface of the electrode assembly facing the inner surface;
The power storage device according to claim 1, wherein the shielding member integrally includes the shielding portion and the covering portion, and has an opening between the shielding portion and the covering portion. A tab group in which tabs in a shape protruding from a part of one side of the electrode are laminated with the same polarity,
A conductive member joined to the tab group and interposed between the wall portion and the tab group;
An insulating cover for insulating the wall portion and the conductive member;
The power storage device according to claim 1, wherein the insulating cover also functions as the covering portion.   The power storage device according to any one of claims 1 to 3, wherein the power storage device is a secondary battery.

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