JP2014203708A - Power storage device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce variations in an opening shape and an opening area of a pressure release valve.SOLUTION: A power storage device includes an intersection groove 23 in a valve body 21 of a pressure release valve 20. The intersection groove 23 has an intersection part P in which a straight groove 24 and a straight groove 25 intersect with each other. In the intersection grooves 24 and 25, an angle between opening ends 28 on both ends of the groove and the deepest part of the groove is reduced between from ends 24a and 25a of the groove to the intersection part P capable of becoming a cleavage start point.

Description

  The present invention relates to a power storage device having a pressure release valve that releases pressure inside a case to the outside of the 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 is disclosed in Patent Document 1, for example. The secondary battery has an electrode assembly in which a negative electrode obtained by applying a negative electrode active material to a metal foil and a positive electrode obtained by applying a positive electrode active material to a metal foil are insulated with a separator and laminated in layers. And the electrode assembly and electrolyte solution are accommodated in the case of the secondary battery. Further, the case of the secondary battery is provided with a pressure release valve (gas discharge valve) that releases the pressure inside the case to the outside of the case.

JP 2011-181214 A

When variation occurs in the position where the pressure release valve starts to be opened, the opening shape and the opening area of the valve also vary. As a result, there is a possibility that the pressure in the case cannot be sufficiently released.
The present invention has been made paying attention to such problems existing in the prior art, and an object thereof is to provide a power storage device capable of reducing variations in the opening shape and opening area of the pressure release valve. There is to do.

  A power storage device that solves the above problem is a power storage device having a pressure release valve that opens a pressure in the case to a case in which an electrode assembly is housed, and the pressure release valve includes a cleavage start point, A groove including a cleavage starting point, and the groove has an angular change in which an angle between an opening end on both sides of the groove and a deepest part of the groove decreases from the groove end to the cleavage starting point. Part.

  According to this configuration, the position where the angle is the smallest by the groove having the angle changing portion can be determined as the position where the cleavage starts, and the cleavage is easily started from that position. As a result, variations in the opening shape and opening area of the pressure release valve can be reduced.

  In the above power storage device, it is preferable that the groove includes an intersecting groove, and the cleavage start point is an intersecting portion of the intersecting groove. According to this configuration, the pressure release valve can be cleaved in a well-balanced manner by defining the intersecting portion as a position where the cleaving starts. Therefore, variations in the opening shape and opening area of the pressure release valve can be reduced.

  In the above power storage device, it is preferable that the angle change portion is located in a range from the end portion to the cleavage start point. According to this configuration, the position where the angle is the smallest in the groove can be reliably determined as the position where the cleavage starts.

  In the above power storage device, it is preferable that the angle changing unit changes the angle constantly. According to this structure, since it can be set as a regular groove | channel, a cleavage can be performed rapidly.

  A power storage device that solves the above-described problem is a power storage device that includes a pressure release valve that opens a pressure in the case to the outside of the case in which the electrode assembly is housed, and the pressure release valve includes a cleavage start point. 1 and a second groove that does not include the cleavage start point, and the angle between the open ends of the first groove on both sides of the first groove and the deepest part of the first groove is The angle between the open ends of the second groove on both sides of the second groove and the deepest portion of the second groove is small.

  According to this configuration, it is possible to determine the position where the cleavage starts in the first groove having a small angle, and the cleavage is likely to start from that position. As a result, variations in the opening shape and opening area of the pressure release valve can be reduced.

  In the above power storage device, it is preferable that the first groove has an angle changing portion in which the angle decreases between an end portion of the first groove and the cleavage start point. According to this configuration, the position where the angle is the smallest in the first groove can be determined as the position where the cleavage starts, and the cleavage is likely to start from that position. Therefore, variations in the opening shape and opening area of the pressure release valve can be reliably reduced.

  In the above power storage device, a preferable example of the power storage device is a secondary battery.

  According to the present invention, variations in the opening shape and opening area of the pressure release valve can be reduced.

The perspective view which shows the external appearance of a secondary battery. The top view which shows the surface of the pressure release valve of 1st Embodiment. (A) is a sectional view taken along line 1-1, and (b) is a sectional view taken along line 2-2. The top view which shows the surface of the pressure release valve of 2nd Embodiment. The top view which shows the surface of the pressure release valve of 3rd Embodiment. The top view which shows the surface of the pressure release valve of 4th Embodiment. (A) is a sectional view taken along line 3-3, (b) is a sectional view taken along line 4-4, and (c) is a sectional view taken along line 5-5. The top view which shows the surface of the pressure release valve in another example.

(First embodiment)
Hereinafter, a first embodiment embodying a power storage device will be described with reference to FIGS.
As shown in FIG. 1, in a secondary battery 10 as a power storage device, an electrode assembly 12 is accommodated in a case 11. The case 11 also contains an electrolyte solution together with the electrode assembly 12. The case 11 includes a bottomed cylindrical case main body 13 and a flat lid 14 that closes an opening for inserting the electrode assembly 12 into the case main body 13. Both the case main body 13 and the lid body 14 are made of metal (for example, stainless steel or aluminum). In addition, the secondary battery 10 of this embodiment is a rectangular battery whose appearance is a rectangular shape because the case body 13 has a bottomed rectangular tube shape and the lid body 14 has a rectangular flat plate shape. Moreover, the secondary battery 10 of this embodiment is a lithium ion battery.

  The electrode assembly 12 includes a positive electrode, a negative electrode, and a separator that insulates the positive electrode from the negative electrode. The positive electrode is configured by applying a positive electrode active material to both surfaces of a positive metal foil (aluminum foil). The negative electrode is configured by applying a negative electrode active material to both surfaces of a negative electrode metal foil (copper foil). The electrode assembly 12 has a stacked structure in which a plurality of positive electrodes and a plurality of negative electrodes are alternately stacked and a separator is interposed between the electrodes. In addition, a positive electrode terminal 15 and a negative electrode terminal 16 are electrically connected to the electrode assembly 12. Each part of the positive electrode terminal 15 and the negative electrode terminal 16 is exposed to the outside of the case 11 from the lid body 14. Further, a ring-shaped insulating ring 17 a for insulating from the case 11 is attached to the positive terminal 15 and the negative terminal 16, respectively.

  In addition, the lid 14 of the case 11 is provided with a liquid injection hole 18 for injecting an electrolyte into the case 11 (case body 13). The liquid injection hole 18 is closed by a sealing member 19. Has been. The sealing member 19 is fixed to the surface 14 a (surface outside the case) of the lid body 14 and is exposed outside the case 11. Further, the pressure release valve 20 that is opened when the pressure in the case 11 reaches an open pressure, which is a predetermined pressure, and communicates the inside and outside of the case so that the pressure in the case 11 does not increase excessively. Is provided. In this embodiment, the pressure release valve 20 is located on the lid 14 of the case 11. Further, in the lid body 14, the sealing member 19 (the liquid injection hole 18) and the pressure release valve 20 are positioned side by side. The release pressure of the pressure release valve 20 is set to a pressure at which the case 11 itself and the joint between the case body 13 and the lid body 14 can be broken before cracks or breakage can occur. The pressure release valve 20 has a thin plate-like valve body 21 that is thinner than the plate thickness of the lid body 14. The valve body 21 is located at the bottom of a recess 22 that is recessed in the upper surface of the lid body 14, and is molded integrally with the lid body 14.

As shown in FIG. 2, the pressure relief valve 20 has a circular periphery. The valve body 21 is connected to the periphery of the pressure release valve 20 and has a circular shape like the pressure release valve 20.
The surface 21 a of the valve body 21 has a cross groove 23. The intersecting groove 23 includes two straight grooves 24 and 25 extending linearly between the peripheral edges of the valve body 21. The intersection groove 23 has an intersection P at a position where the two linear grooves 24 and 25 intersect. In this embodiment, the intersection P of the intersection groove 23 is located in the center of the valve body 21. Further, the two straight grooves 24 and 25 intersect at the intersecting portion P, and end portions 24a and 25a on both sides of the respective straight grooves 24 and 25 are located in the vicinity of the peripheral edge of the valve body 21. The two linear grooves 24 and 25 have an opening width 26 that narrows from the end portions 24 a and 25 a toward the intersection P, and the opening width 26 is the narrowest at the intersection P. Here, the “opening width” means that on the surface 21 a of the valve body 21, the linear grooves 24, 25 and the surface 21 a of the valve body 21 are arranged at positions orthogonal to the direction in which the linear grooves 24, 25 extend. The width between the boundaries.

  As shown in FIGS. 3A and 3B, the straight groove 24 (“D1” and “D2” in the figure) has the same groove depth 27 and the openings on both sides of the straight groove 24. An angle 30 between the end 28 and the deepest portion 29 of the linear groove 24 decreases in a range from the end 24 a of the linear groove 24 to the intersection P. As the angle 30 is decreased, the opening width 26 of the linear groove 24 becomes narrower from the end 24a toward the intersection P as shown in FIG. The groove depth 27 is the length when the deepest portion 29 of the groove and the surface of the valve body are connected by a straight line along the thickness direction of the valve body. Further, the opening ends 28 on both sides of the groove are the ends where the groove surface extending from the deepest portion 29 of the groove to the surface of the valve body intersects the surface of the valve body.

  In the straight groove 24, the angle 30 from the end 24a to the intersection P is changed constant. The constant change means not only that the angle changes continuously and the amount of change, but also that the angle changes stepwise and the amount of change at each step is constant. In this embodiment, the angle 30 of the linear groove 24 changes continuously, and the amount of change is also constant. By reducing the angle 30 in this way, the groove of the valve body 21 has an angle changing portion.

  The straight groove 25 has the same shape as the straight groove 24 and has an angle changing portion like the straight groove 24. That is, as shown in FIGS. 3A and 3B, the straight grooves 25 (“D1” and “D2” in the figure) have an opening end 28 on both sides of the straight grooves 25 and a deepest portion 29 of the straight grooves 25. Is reduced in the range from the end 25a of the linear groove 25 to the intersection P. The valve body 21 of the pressure release valve 20 includes a thin film portion 31 between the bottoms of the straight grooves 24 and 25 and the back surface 21b of the valve body 21. The thin film portion 31 is thinner than the thickness of the valve body 21.

Hereinafter, the operation of this embodiment will be described.
The pressure in the case 11 is applied so that the valve body 21 is expanded outward when the back surface 21b of the valve body 21 becomes a pressure receiving surface. Further, stress is generated in the intersecting groove 23 of the valve body 21 by the pressure applied from the inside of the case 11.

  In this embodiment, the angle 30 of the straight grooves 24 and 25 at the intersection P is the smallest. Thereby, the angle 30 of the straight grooves 24 and 25 in the intersection P becomes a sharper angle than the angles of other groove portions other than the intersection P. For this reason, the pressure applied from the inside of the case 11 is likely to concentrate on the intersection P, and the valve element 21 is likely to start to break starting from the intersection P. That is, the intersecting portion P is assumed as a cleavage starting point which is a starting point when the valve body 21 starts to be cleaved.

  When the pressure in the case 11 reaches the opening pressure, the intersecting groove 23 is cleaved starting from the intersecting portion P. When the intersecting groove 23 on the surface 21a of the valve body 21 is thus cleaved, the valve body 21 is turned up outside while being divided into a plurality of regions. Thereby, a large opening is generated in the pressure release valve 20. The pressure in the case 11 is released to the outside of the case 11 through an opening generated in the pressure release valve 20.

Therefore, according to the present embodiment, the following effects can be obtained.
(1) The intersecting portion P of the intersecting groove 23 can be determined as a position where the cleavage starts, and the cleavage is easily started from the intersecting portion P as a starting point. As a result, variations in the opening shape and the opening area of the pressure release valve 20 can be reduced. Therefore, the pressure in the case 11 can be sufficiently released.

  (2) By defining the intersecting portion P of the intersecting groove 23 as a position where the cleavage starts, the pressure release valve 20 can be cleaved with a good balance. Therefore, variations in the opening shape and opening area of the pressure release valve 20 can be reduced.

  (3) Moreover, by having the crossing groove 23, it is possible to expand the cleavage radially by the crossing groove 23 at the initial stage of the cleavage. Accordingly, it is possible to improve the speed in releasing the pressure in the case 11.

(4) By changing the angle 30 to be constant, the intersecting grooves 23 become regular grooves. For this reason, the load of cleavage can be stabilized and cleavage can be performed rapidly.
(5) Since the intersecting portion P is positioned at the center of the valve body 21, the valve body 21 can be cleaved with good balance.

(Second Embodiment)
Next, a second embodiment in which the power storage device is embodied will be described with reference to FIG.
Note that, in the embodiment described below, the same components as those already described in the embodiment are denoted by the same reference numerals, and redundant description thereof is omitted or simplified.

  As shown in FIG. 4, the pressure release valve 32 of this embodiment has a track-shaped periphery in which two parallel straight portions 33 and 34 are connected by arc portions 35 and 36. The valve element 37 of the pressure release valve 32 is connected to the periphery of the pressure release valve 32 and has a track shape like the pressure release valve 32.

  The arc portion 35 has one end connected to one end of the straight portion 33 and the other end connected to one end of the straight portion 34. The arc portion 36 has one end connected to the other end of the straight portion 33 and the other end connected to the other end of the straight portion 34. That is, in this embodiment, one end portion of the straight portions 33 and 34 is connected by an arc portion 35 having an arc shape as a whole, and the other end portion of the straight portions 33 and 34 has an arc shape as a whole. Connected by the arc portion 36. In the pressure release valve 32, the portion where the end portions of the straight portions 33 and 34 and the end portions of the arc portions 35 and 36 are connected is the boundary P1, P2, P3, P4 between the straight portions 33 and 34 and the arc portions 35 and 36. Become.

  The surface 37a of the valve body 37 has a groove. The groove includes an intersecting groove 38 and a plurality of arc-shaped grooves 39 and 40 along the arc portions 35 and 36. In this embodiment, the intersecting groove 38 and the arc-shaped grooves 39 and 40 are both V-shaped grooves.

  The intersecting groove 38 includes two straight grooves 41 and 42. The straight grooves 41 and 42 are positioned on virtual straight lines Y1 and Y2 that intersect the arc portions 35 and 36 that are the peripheral edges of the pressure release valve 32, respectively. The virtual straight lines Y1 and Y2 intersect the virtual line indicated by the two-dot chain line in the diagram connecting the boundaries P1 and P3, and the virtual line indicated by the two-dot chain line in the diagram connecting the boundaries P2 and P4. The intersecting groove 38 has an intersecting portion P at a position where the two straight grooves 41 and 42 intersect. The intersection P includes intersections of virtual straight lines Y1 and Y2. In this embodiment, the intersection P of the intersection groove 38 is located at the center of the valve body 37.

  Further, the surface 37 a of the valve body 37 has two arc-shaped grooves 39 along the arc portion 35 and two arc-shaped grooves 40 along the arc portion 36. Of the two arc-shaped grooves 39, one arc-shaped groove 39 is connected to one end located on the boundary P <b> 1 side in the linear groove 41, and extends in an arc shape along the arc portion 35. Of the two arc-shaped grooves 40, one arc-shaped groove 40 is connected to one end located on the boundary P <b> 2 side in the linear groove 42, and extends in an arc shape along the arc portion 36. . Of the two arc-shaped grooves 39, the other arc-shaped groove 39 is connected to the other end located on the boundary P <b> 3 side in the linear groove 42, and extends in an arc shape along the arc portion 35. . Of the two arc-shaped grooves 40, the other arc-shaped groove 40 is connected to the other end located on the boundary P <b> 4 side in the linear groove 41, and extends in an arc shape along the arc portion 36. . Each arcuate groove 39, 40 bisects the valve body 37 in a direction in which the position of the end opposite to the end connected to the straight grooves 41, 42 is perpendicular to the direction in which the straight portions 33, 34 extend. The length is a position that is separated from the bisector L1 indicated by a one-dot chain line in the inside at a predetermined distance. That is, each arcuate groove 39, 40 is provided along a part of the arc portions 35, 36.

  In this embodiment, the straight groove 41 ("D2" in the figure) shown in FIG. 3B and the arc-shaped grooves 39 and 40 ("D1" in the figure) connected to the straight groove 41 shown in FIG. The groove depth 27 is the same depth. On the other hand, the angle 30 between the opening ends 28 on both sides of the linear groove 41 and the deepest portion 29 of the linear groove 41 shown in FIG. 3B is the opening end on both sides of the arc-shaped grooves 39 and 40 shown in FIG. It is smaller than the angle 30 between 28 and the deepest part 29 of the arc-shaped grooves 39 and 40. Thereby, in the cleavage groove | channel 43 containing the linear groove | channel 41 and the arc-shaped grooves 39 and 40, in the range from the edge parts 39a and 40a on the opposite side to the edge part of the arc-shaped grooves 39 and 40 connected with the linear groove 41 to the cross | intersection part P Angle 30 is decreasing. As the angle 30 decreases, the opening width 26 of the cleavage groove 43 becomes narrower from the end portion 39a toward the intersecting portion P and the opening width 26 becomes smaller from the end portion 40a toward the intersecting portion P as shown in FIG. Narrow. In this embodiment, the angle 30 changes stepwise by making the angle 30 of the linear groove 41 different from the angle 30 of the arcuate grooves 39 and 40. Further, the amount of change between the angle 30 of the linear groove 41 and the angle 30 of the arc-shaped grooves 39 and 40 is constant. By reducing the angle 30 in this way, the groove of the valve body 37 has an angle changing portion.

  The linear groove 42 has the same shape as the linear groove 41, and the arc-shaped grooves 39 and 40 connected to the linear groove 42 have the same shape as the arc-shaped grooves 39 and 40 connected to the linear groove 41. For this reason, the cleavage groove 44 including the straight groove 42 and the arc-shaped grooves 39 and 40 has the same shape as the cleavage groove 43. In addition, the cleavage groove 44 has an angle change portion as with the cleavage groove 43. That is, the angle 30 of the cleavage groove 44 is reduced in the range from the end portions 39a, 40a opposite to the end portions of the arc-shaped grooves 39, 40 connected to the linear groove 42 to the intersection P. Thereby, as shown in FIG. 4, the opening width 26 of the cleavage groove 44 becomes narrower from the end portion 39 a toward the intersecting portion P, and the opening width 26 becomes narrower from the end portion 40 a toward the intersecting portion P. The valve body 37 of the pressure release valve 32 includes the thin film portion 31 between the bottoms of the straight grooves 41 and 42 and the back surface 37 b of the valve body 37, and the bottoms of the arc-shaped grooves 39 and 40 and the back surface of the valve body 37. The thin film portion 31 is provided between the thin film portion 37b and the thin film portion 31b.

  Further, on the surface 37 a of the valve body 37, assuming virtual straight lines Y <b> 1 and Y <b> 2 along the intersecting grooves 38, a plurality of regions S <b> 1, S <b> 2, S <b> 3 surrounded by the virtual straight lines Y <b> 1 and Y <b> 2 and the periphery of the pressure release valve 32. S4 is assumed. In the region S1, the virtual straight line Y1 located between the intersection P of the intersection groove 38 and the intersection where the virtual straight line Y1 intersects the arc 35, and the intersection P and the virtual straight line Y2 intersect the arc 36. This is a region partitioned by the portion of the virtual straight line Y2 located between the intersecting portion and the straight portion 33. In addition, the region S2 includes a portion of the virtual straight line Y2 located between the intersection P and the intersection where the virtual straight line Y2 intersects the arc 35, and an intersection where the intersection P and the virtual straight line Y1 intersect the arc 36. This is a region defined by the portion of the virtual straight line Y1 located between the straight line portion 34 and the virtual straight line Y1. The region S1 and the region S2 are point symmetric with respect to the intersection of the virtual straight line Y1 and the virtual straight line Y2.

  The area S3 includes a portion of the virtual straight line Y1 located between the intersection P and the intersection where the virtual straight line Y1 intersects the arc 35, and an intersection where the intersection P and the virtual straight line Y2 intersect the arc 35. This is a region partitioned by the portion of the virtual straight line Y2 located between and the arc portion 35. Further, the region S4 includes a portion of the virtual straight line Y2 located between the intersection P and the intersection where the virtual straight line Y2 intersects the arc 36, and an intersection where the intersection P and the virtual straight line Y1 intersect the arc 36. This is a region partitioned by the portion of the virtual straight line Y1 located between the arc portion 36 and the virtual straight line Y1. The region S3 and the region S4 are point symmetric with the intersection of the virtual straight line Y1 and the virtual straight line Y2 as the center of symmetry.

  In this embodiment, the regions S1 and S2 are regions including the straight portions 33 and 34, and are in contact with the entirety of the straight portions 33 and 34 while slightly touching the arc portions 35 and 36. On the other hand, in this embodiment, the regions S3 and S4 are regions including the arc portions 35 and 36, and are in contact with almost the entire arc portions 35 and 36. In this embodiment, the regions S1 and S2 are second regions with few portions in contact with the arc portions 35 and 36, and the regions S3 and S4 are first regions with many portions in contact with the arc portions 35 and 36. The area of the four regions S1 to S4 on the surface 37a of the valve body 37 is such that the regions S3 and S4 having more portions in contact with the arc portions 35 and 36 have less portions in contact with the arc portions 35 and 36. , Larger than S2.

Hereinafter, the operation of this embodiment will be described.
In this embodiment, the angle 30 of the straight grooves 41 and 42 constituting the intersecting groove 23 is smaller than the angle 30 of the arcuate grooves 39 and 40. Thereby, the angle 30 of the straight grooves 41 and 42 is sharper than the angle 30 of the arcuate grooves 39 and 40. The straight grooves 41 and 42 include an intersection P. For this reason, the pressure applied from the inside of the case 11 is likely to concentrate on the intersection P, and the valve element 21 is likely to start to break starting from the intersection P. That is, the intersecting portion P is assumed as a cleavage starting point that is a starting point when the valve body 37 starts to be cleaved. When the pressure in the case 11 reaches the open pressure, the valve element 37 is cleaved starting from the intersection P.

  Further, in this embodiment, the cracking starts from the intersection P, and when the straight grooves 41 and 42 reach the ends connected to the arcuate grooves 39 and 40, the arcuate grooves 39 and 40 also start to crack. By this cleavage, the valve body 37 is divided into four regions S1 to S4 along the grooves that define the regions S1 to S4.

  At this time, in this embodiment, the areas of the regions S3 and S4 having many portions in contact with the arc portions 35 and 36 are made larger than the areas of the regions S1 and S2 having many portions in contact with the straight portions 33 and 34. . That is, the areas S3 and S4 have a larger pressure receiving area than the areas S1 and S2. For this reason, the pressure receiving amount of the pressure applied from the inside of the case 11 to the back surface 37b of the valve body 37 is larger in the regions S3 and S4 than in the regions S1 and S2.

  Therefore, according to this embodiment, in addition to the effects (1) to (5) of the first embodiment, the following effects can be obtained. The effects (1) to (5) are as follows: “pressure release valve 20” is “pressure release valve 32”, “valve body 21” is “valve body 37”, and “crossing groove 23” is “crossing groove 38”. , And shall be read respectively.

  (6) The arc-shaped grooves 39 and 40 are less likely to be cleaved than the straight grooves 41 and 42. For this reason, by increasing the area of the regions S3 and S4 with many portions in contact with the arc portions 35 and 36 as compared with the areas of the regions S1 and S2 with few portions in contact with the arc portions 35 and 36, the regions S3 and S4. The amount of pressure received increases. Therefore, even in the pressure release valve 32 having the arc-shaped grooves 39 and 40 along the arc portions 35 and 36 in order to enlarge the opening of the pressure release valve 32, the cleavage of the arc-shaped grooves 39 and 40 is promoted to promote the region. S3 and S4 are easily opened outward. As a result, the balance of the opening of the pressure release valve 32 is improved, and the opening of the pressure release valve 32 can be increased. That is, the pressure in the case 11 can be quickly released.

  Incidentally, when the amount of pressure received in the regions S3 and S4 in contact with the arc portions 35 and 36 is small, the arc-shaped grooves 39 and 40 may not be sufficiently cleaved. That is, when the balance of the opening of the pressure release valve 32 is poor, the arc-shaped grooves 39 and 40 are not sufficiently cleaved, and as a result, the opening of the pressure release valve 32 is also reduced. Therefore, the quickness in releasing the pressure in the case 11 is impaired.

  (7) The intersecting groove 38 has two straight grooves 41 and 42. For this reason, the cleavage is promoted by the linear grooves 41 and 42 at the initial stage of the cleavage of the valve element 37. Accordingly, it is possible to improve the speed in releasing the pressure in the case 11.

  (8) By making the pressure release valve 32 into a track shape, the opening of the pressure release valve 32 can be set larger than in the case of making the pressure release valve 32 into a square shape. Accordingly, it is possible to improve the speed in releasing the pressure in the case 11.

  (9) Since the straight grooves 41 and 42 extend to the vicinity of the boundaries P1 to P4, the arc-shaped grooves 39 and 40 can be arranged along the arc portions 35 and 36. Therefore, when each groove of the valve body 37 is cleaved, the opening of the pressure release valve 32 can be increased.

  (10) The arc-shaped grooves 39 and 40 are provided along part of the arc portions 35 and 36. For this reason, even if each groove | channel cleaves and it turns up outside, the valve body 37 is connected in the location in which the groove | channel is not provided. Therefore, the fragments of the valve body 37 can be prevented from scattering.

  (11) Since the straight grooves 41 and 42 and the arc-shaped grooves 39 and 40 are connected, after the straight grooves 41 and 42 are cleaved, the arc-shaped grooves 39 and 40 can be promptly shifted to cleave. The pressure release valve 32 is divided into the regions S1 to S4 by the cleavage of the linear grooves 41 and 42, and an opening is generated when the valve body 37 is turned up to the outside in accordance with the progress of the cleavage. Open to the outside. For this reason, the opening amount of the pressure release valve 32 can be sufficiently ensured by quickly shifting the cleavage from the straight grooves 41 and 42 to the arc-shaped grooves 39 and 40.

(Third embodiment)
Next, a third embodiment in which the power storage device is embodied will be described with reference to FIG.
As shown in FIG. 5, the surface 37a of the valve element 37 of the pressure release valve 32 of this embodiment has an intersecting groove 38 composed of linear grooves 41, 42 and arc portions 35, 36, as in the second embodiment. Arcuate grooves 39 and 40 along In this embodiment, the straight grooves 41 and 42 and the arcuate grooves 39 and 40 are not connected.

  Further, as shown in FIGS. 3A and 3B, the angle 30 of the straight grooves 41 and 42 (“D2” in the figure) is set to the angle 30 of the arc-shaped grooves 39 and 40 (“D1” in the figure). Smaller than that. As shown in FIG. 5, the opening width 26 of the linear grooves 41 and 42 is narrower than the opening width 26 of the arc-shaped grooves 39 and 40. Thereby, the intersection part P of the intersection groove | channel 38 is assumed as a cleavage starting point which is a starting point when the valve body 37 starts a cleavage similarly to 2nd Embodiment. Therefore, in this embodiment, the intersecting groove 38 (straight grooves 41 and 42) is the first groove including the cleavage starting point, and the arc-shaped grooves 39 and 40 are the second grooves not including the cleavage starting point.

  Further, on the surface 37a of the valve body 37, a plurality of regions S1, S2, S3, S4 surrounded by the virtual straight lines Y1, Y2 and the peripheral edge of the pressure release valve 32 are assumed by the intersecting grooves 38 and the arc-shaped grooves 39, 40. The The area of the four regions S1 to S4 on the surface 37a of the valve body 37 is such that the regions S3 and S4 having more portions in contact with the arc portions 35 and 36 have less portions in contact with the arc portions 35 and 36. , Larger than S2.

Hereinafter, the operation of this embodiment will be described.
In this embodiment, similarly to the second embodiment, the angle 30 of the straight grooves 41 and 42 is made smaller than the angle 30 of the arc-shaped grooves 39 and 40. For this reason, the pressure applied from the inside of the case 11 is likely to concentrate on the intersection P, and the valve element 21 is likely to start to break starting from the intersection P.

  The valve body 37 starts to be cleaved starting from the intersection P, and when the straight grooves 41 and 42 reach the end close to the arc-shaped grooves 39 and 40, the arc-shaped grooves 39 and 40 also start to cleave. By this cleavage, the valve body 37 is divided into four regions S1 to S4 along the grooves that define the regions S1 to S4. Further, the pressure receiving amount of the pressure applied from the inside of the case 11 to the back surface 37b of the valve body 37 is larger in the regions S3 and S4 than in the regions S1 and S2.

Therefore, according to this embodiment, in addition to the effects (1) to (5) of the first embodiment and the effects (6) to (10) of the second embodiment, the following effects can be obtained. Can do.
(12) Since the cross groove 38 and the arc-shaped grooves 39 and 40 are not connected, the cross groove 38 having the cross portion P can be reliably cleaved.

(Fourth embodiment)
Next, a fourth embodiment in which the power storage device is embodied will be described with reference to FIGS.
As shown in FIG. 6, the surface 37a of the valve element 37 of the pressure release valve 32 of this embodiment has an intersecting groove 38 composed of linear grooves 41, 42 and arc portions 35, 36, as in the second embodiment. Arcuate grooves 39 and 40 along In this embodiment, the straight grooves 41 and 42 and the arcuate grooves 39 and 40 are connected.

  As shown in FIGS. 7A and 7B, the linear groove 41 has the same groove depth 27, and the opening end 28 on both sides of the linear groove 41 and the deepest portion 29 of the linear groove 41 are not shown. The angle 30 decreases in a range from the end portion connected to the arc-shaped grooves 39 and 40 in the linear groove 41 to the intersection P. As the angle 30 decreases, the opening width 26 of the linear groove 41 becomes narrower from the end connected to the arc-shaped grooves 39 and 40 toward the intersection P as shown in FIG.

  As shown in FIG. 7C, the arc-shaped grooves 39 and 40 connected to the linear groove 41 have the same groove depth 27 as that of the linear groove 41. The arc-shaped grooves 39, 40 are configured so that the angle 30 between the open ends 28 on both sides of the arc-shaped grooves 39, 40 and the deepest portion 29 of the arc-shaped grooves 39, 40 is the end of the linear groove 41 that is connected to the arc-shaped grooves 39, 40. Larger than angle 30. For this reason, the arc-shaped grooves 39 and 40 are wider than the opening width 26 of the linear groove 41 as shown in FIG.

  Thereby, in the cleavage groove | channel 43 containing the linear groove | channel 41 and the arc-shaped grooves 39 and 40, in the range from the edge parts 39a and 40a on the opposite side to the edge part of the arc-shaped grooves 39 and 40 connected with the linear groove 41 to the cross | intersection part P Angle 30 is decreasing. As the angle 30 decreases, the opening width 26 of the cleavage groove 43 becomes narrower from the end portion 39a toward the intersecting portion P and the opening width 26 becomes smaller from the end portion 40a toward the intersecting portion P as shown in FIG. Narrow. In this embodiment, the angle 30 changes stepwise between the linear groove 41 and the arcuate grooves 39, 40 and continuously changes in the linear groove 41. By reducing the angle 30 in this way, the groove of the valve body 37 has an angle changing portion.

  The linear groove 42 has the same shape as the linear groove 41, and the arc-shaped grooves 39 and 40 connected to the linear groove 42 have the same shape as the arc-shaped grooves 39 and 40 connected to the linear groove 41. For this reason, the cleavage groove 44 including the straight groove 42 and the arc-shaped grooves 39 and 40 has the same shape as the cleavage groove 43. In addition, the cleavage groove 44 has an angle change portion as with the cleavage groove 43. That is, the angle 30 of the cleavage groove 44 is reduced in the range from the end portions 39a, 40a opposite to the end portions of the arc-shaped grooves 39, 40 connected to the linear groove 42 to the intersection P. Thereby, as shown in FIG. 6, the opening width 26 of the cleavage groove 44 becomes narrower from the end portion 39 a toward the intersecting portion P, and the opening width 26 becomes narrower from the end portion 40 a toward the intersecting portion P. The valve body 37 of the pressure release valve 32 includes the thin film portion 31 between the bottoms of the straight grooves 41 and 42 and the back surface 37 b of the valve body 37, and the bottoms of the arc-shaped grooves 39 and 40 and the back surface of the valve body 37. The thin film portion 31 is provided between the thin film portion 37b and the thin film portion 31b.

  Further, on the surface 37a of the valve body 37, a plurality of regions S1, S2, S3, S4 surrounded by the virtual straight lines Y1, Y2 and the peripheral edge of the pressure release valve 32 are assumed by the intersecting grooves 38 and the arc-shaped grooves 39, 40. The The area of the four regions S1 to S4 on the surface 37a of the valve body 37 is such that the regions S3 and S4 having more portions in contact with the arc portions 35 and 36 have less portions in contact with the arc portions 35 and 36. , Larger than S2.

Hereinafter, the operation of this embodiment will be described.
In this embodiment, the angle 30 of the linear grooves 41 and 42 at the intersection P is the smallest. Thereby, the angle 30 of the linear grooves 41 and 42 in the crossing part P becomes sharper than the angle of other groove parts other than the crossing part P. For this reason, the pressure applied from the inside of the case 11 is likely to concentrate on the intersection P, and the valve element 37 is likely to start to break starting from the intersection P. That is, the intersecting portion P is assumed as a cleavage starting point that is a starting point when the valve body 37 starts to be cleaved.

  The valve body 37 starts to be cleaved starting from the intersection P, and when the straight grooves 41 and 42 reach the end close to the arc-shaped grooves 39 and 40, the arc-shaped grooves 39 and 40 also start to cleave. By this cleavage, the valve body 37 is divided into four regions S1 to S4 along the grooves that define the regions S1 to S4. Further, the pressure receiving amount of the pressure applied from the inside of the case 11 to the back surface 37b of the valve body 37 is larger in the regions S3 and S4 than in the regions S1 and S2.

Therefore, according to this embodiment, in addition to the effects (1) to (5) of the first embodiment and the effects (6) to (11) of the second embodiment, the following effects can be obtained. Can do.
(13) The intersecting portion P of the intersecting groove 23 can be determined as a position where the cleavage starts, and the cleavage is easily started from the intersecting portion P as a starting point. As a result, variations in the opening shape and the opening area of the pressure release valve 32 can be reliably reduced.

In addition, you may change this embodiment as follows.
FIG. 8 shows a configuration similar to that of the linear grooves 41 and 42 in the valve body 37 of the fourth embodiment shown in FIG. 6 in the linear grooves 41 and 42 of the valve body 37 of the third embodiment shown in FIG. The valve element 37 of the pressure release valve 32 when employed is shown. In this other example, the angle 30 of the straight grooves 41 and 42 intersects from end portions 41a and 42a opposite to the intersecting portion P in the straight grooves 41 and 42 as shown in FIGS. 7 (a) and 7 (b). It decreases in the range up to part P. As the angle 30 decreases, the opening width 26 of the linear grooves 41 and 42 becomes narrower from the end portions 41a and 42a of the linear grooves 41 and 42 toward the intersection P as shown in FIG. According to this structure, there exists an effect similar to 3rd Embodiment and 4th Embodiment.

The cross grooves 23 and 38 may be changed to a Y shape instead of the X shape.
○ The cross-sectional shape of each groove may be changed.
○ The shape of the case 11 may be changed. For example, the case 11 may be cylindrical.

The pressure release valves 20 and 32 may be separate parts from the case 11, and the pressure release valves 20 and 32 may be joined to the case 11. Joining is performed by welding (for example, laser welding), for example.
The electrode assembly 12 is not limited to the laminated type, and may be a wound type in which a belt-like positive electrode and a belt-like negative electrode are wound and laminated in layers.

  The secondary battery 10 is a lithium ion secondary battery, but is not limited thereto, and may be another secondary battery. 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. Further, a capacitor may be used as the power storage device.

(Circle) the secondary battery 10 may be mounted in a motor vehicle as a vehicle power supply device, and may be mounted in an industrial vehicle. Further, the present invention may be applied to a stationary power storage device.
In the valve bodies 21 and 37, grooves may be provided on the back surfaces 21b and 37b.

  O You may change the shape of the groove | channel provided in the valve bodies 21 and 37. FIG. For example, a single linear groove or a groove having no intersection, such as a “C” -shaped groove, may be used. In addition, as in each embodiment, these grooves are provided with angle changing portions in which the angle between the open ends on both sides of the groove and the deepest portion of the groove decreases from the end of the groove to the cleavage start point.

  In the first embodiment, the groove depth 27 of the intersecting groove 23 may be changed. In this case, the groove depth 27 is changed so as to become deeper toward the intersecting portion P that becomes the cleavage starting point. Further, in the second to fourth embodiments and another example of FIG. 8, the groove depth 27 of the intersecting grooves 38 and the arc-shaped grooves 39 and 40 may be changed. In this case, the groove depth 27 of the intersecting groove 38 is changed so as to become deeper toward the intersecting portion P serving as a cleavage starting point. In addition, the groove depth 27 of the arc-shaped grooves 39 and 40 is made deeper from an end portion far from the straight grooves 41 and 42 in the arc-shaped grooves 39 and 40 toward an end portion close to the end portions. Even in this case, the same effect as in the embodiment can be obtained, and the intersecting portion P can be reliably determined as the position where the cleavage starts.

  In the second to fourth embodiments and another example of FIG. 8, the virtual straight lines Y1 and Y2 may be defined as lines passing through the center of the opening width of the groove or as lines passing through the opening end of the groove. You may do it. In any case, the virtual straight lines Y1 and Y2 are lines extending along the groove.

  In the second to fourth embodiments and another example of FIG. 8, the positions where the virtual straight lines Y1 and Y2 intersect the arc portions 35 and 36 are further separated from the respective boundaries P1 to P4 toward the arc portions 35 and 36. The straight grooves 41 and 42 may be provided along these virtual straight lines Y1 and Y2. In this case, the virtual straight lines Y1 and Y2 intersect the peripheral edges of the arc portions 35 and 36. In this case, the regions S1 to S4 are provided so that the area of the region with many portions in contact with the arc portions 35 and 36 is larger than the area of the region with few portions in contact with the arc portions 35 and 36. Even in this case, the same effect as the embodiment can be obtained.

  In the second to fourth embodiments and another example of FIG. 8, the straight grooves 41 and 42 are not limited to being located on the virtual straight lines Y <b> 1 and Y <b> 2 intersecting the arc portions 35 and 36, but the same straight line portion 33. , 34 may be located in a region where the end portions on the boundary side approach each other. The virtual straight lines Y1 and Y2 in this case are extended along the straight grooves 41 and 42 and intersect the straight portions 33 and 34. Even in this case, the same effect as the embodiment can be obtained.

  In the second to fourth embodiments and another example of FIG. 8, the shape of the pressure release valve 32 may be changed to another shape as long as the shape has an arc portion. For example, it may be oval or circular. Moreover, the shape which connected one edge part of the linear parts 33 and 34 with the arc part, and connected the other edge part with the linear part may be sufficient. Moreover, you may vary the shape of the arc part connected to one edge part of the linear parts 33 and 34, and the arc part connected to the other edge part of the linear parts 33 and 34. As shown in FIG. Even in this case, the same effect as the embodiment can be obtained.

  In the third embodiment and another example of FIG. 8, the angle 30 of the intersecting groove 38 may be small if the entire angle 30 in the intersecting groove 38 is smaller than the angle 30 of the arcuate grooves 39 and 40. The average of the angles 30 may be small. Even in this case, the same effect as the embodiment can be obtained.

  In the fourth embodiment and another example of FIG. 8, the arc-shaped grooves 39 and 40 may further have an angle changing portion. That is, the angle 30 of the arc-shaped grooves 39 and 40 may be changed continuously or stepwise. In this case, the angle is increased from the end portion close to the straight grooves 41 and 42 in the arc-shaped grooves 39 and 40 toward the end portion far from the end portions. Even in this case, the same effect as the embodiment can be obtained.

Next, a technical idea that can be grasped from the above embodiment and another example will be added below.
(A) A part of the periphery of the pressure relief valve has an arc portion, and the pressure relief valve has a groove including a cleavage start point. The groove is connected to the cross groove and the end of the cross groove and is along the arc portion. A plurality of arcuate grooves, extending along the intersecting grooves, and assuming a virtual straight line that intersects the peripheral edge of the pressure relief valve, is surrounded by the virtual straight line and the peripheral edge of the pressure relief valve and contacts the arc portion A first region having a large portion and a second region surrounded by a virtual straight line and the periphery of the pressure release valve and having a small portion in contact with the arc portion are assumed, and the area of the first region is the second region. Is larger than the area.

  (B) The peripheral edge of the pressure release valve has a track shape in which parallel straight portions are connected by an arc portion.

  DESCRIPTION OF SYMBOLS 10 ... Secondary battery, 11 ... Case, 12 ... Electrode assembly, 20, 32 ... Pressure release valve, 21, 37 ... Valve body, 21a, 37a ... Surface, 23, 38 ... Cross groove, 24a, 25a, 39a, 40a, 41a, 42a ... end, 28 ... open end, 29 ... deepest part, 30 ... angle, P ... crossing part.

Claims (7)

In a power storage device having a pressure release valve for releasing the pressure in the case to the outside of the case in the case in which the electrode assembly is accommodated,
The pressure relief valve has a cleavage start point and a groove including the cleavage start point,
The power storage device according to claim 1, wherein the groove includes an angle changing portion in which an angle between an opening end on both sides of the groove and a deepest portion of the groove decreases from the end of the groove to the cleavage start point. The groove includes a cross groove,
The power storage device according to claim 1, wherein the cleavage starting point is an intersecting portion of the intersecting groove.   The power storage device according to claim 1, wherein the angle change unit is located in a range from the end to the cleavage start point.   The power storage device according to any one of claims 1 to 3, wherein the angle changing unit changes the angle to be constant. In a power storage device having a pressure release valve for releasing the pressure in the case to the outside of the case in the case in which the electrode assembly is accommodated,
The pressure release valve has a first groove including a cleavage start point, and a second groove not including the cleavage start point,
The angle between the opening ends on both sides of the first groove in the first groove and the deepest portion of the first groove is such that the opening ends on both sides of the second groove in the second groove and the second A power storage device characterized by being smaller than an angle with a deepest portion of the groove.   6. The power storage device according to claim 5, wherein the first groove has an angle changing portion in which the angle decreases between an end portion of the first groove and the cleavage start point.   The power storage device according to any one of claims 1 to 6, wherein the power storage device is a secondary battery.