JP2019133854A - Power storage device - Google Patents

Abstract

To provide a power storage device capable of suppressing rapture of a case during a nail penetration test.SOLUTION: A lid 14 of a secondary battery 10 includes a bulge part 37 where the lid 14 bulges in a convex shape toward the outside of a case. The bulge part 37 includes: a rectangular top plate part 38 located at the tip of the lid 14 in a bulging direction; a short wall part 39a tilted from both edges of the top plate part 38 in a longitudinal direction; and a long wall part 39b extending from both edges of the top plate part 38 in a short direction. Inside the case of the secondary battery 10, a gas passage 56 partitioned by the bulge part 37 and a shield member 50 is provided, and a gas inflow part 57 is also provided.SELECTED DRAWING: Figure 5

Description

  The present invention relates to a power storage device having a pressure release valve that opens the internal pressure of 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. For example, as described in Patent Document 1, the secondary battery includes a case in which an electrode assembly and an electrolytic solution are housed, and a pressure relief valve that releases the pressure inside the case to the outside of the case on the wall portion of the case Is provided.

  In such a secondary battery, when a nail penetration test, which is one of the evaluation tests, is performed, the separator between the positive electrode and the negative electrode is broken by the nail, and the positive electrode and the negative electrode are short-circuited in the case. To do. 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.

  When a part of the electrode is released out of the case, it can spark. In order to prevent the sparks from being scattered, for example, as shown in FIG. 9, Patent Document 1 includes a safety protection device 92 disposed opposite to a pressure relief valve 91 (pressure release valve) provided on the battery upper cover 90. . The safety protection device 92 includes a baffle plate 93 that faces the pressure relief valve 91 and covers the pressure relief valve 91, and a pair of frame-shaped side walls 94 that are erected from the baffle plate 93. Further, the safety protection device 92 includes a first gas flow passage 95 formed in the frame of each side wall 94 and a second gas flow passage 96 that opens at a position sandwiched between the side walls 94. Further, the safety protection device 92 includes an integral flange-like connection portion 98 at the end of the side wall 94.

  In the nail penetration test, even if a part of the electrode is scraped by the gas, a part of the electrode is rebounded by the baffle plate 93 together with the gas. Then, it is suppressed that a part of electrode is discharged | emitted out of a case with gas, and scattering of a spark is suppressed. The gas from which a part of the electrode has been removed is discharged from the pressure relief valve 91 to the outside of the case via the gas flow passages 95 and 96.

Japanese Patent Laid-Open No. 2006-96129

  However, if the gas generated during the nail penetration test cannot be completely discharged from the case through the pressure relief valve 91, the case may burst due to an increase in the internal pressure of the case, so that the generated gas is efficiently discharged out of the case. It is hoped that.

  The objective of this invention is providing the electrical storage apparatus which can suppress rupture of a case at the time of a nail penetration test.

  A power storage device for solving the above problems includes a rectangular parallelepiped electrode assembly having a layered structure in which electrodes of different polarities are insulated from each other, an electrolytic solution, the electrode assembly, and the electrolytic solution A case having a rectangular box-like case main body and a rectangular plate-like lid closing the opening of the case main body, and present in the lid, and is cleaved when the internal pressure of the case reaches an open pressure. A power release device comprising: a pressure release valve that opens the internal pressure of the case to the outside of the case; and a shielding member that covers the pressure release valve from the electrode assembly side in the case, wherein the lid is The lid includes a bulging portion that bulges outwardly from the case, and the bulging portion is located at a distal end of the lid in the bulging direction, and the lid Is a rectangular shape extending in the longitudinal direction, A top plate portion on which the pressure release valve is arranged, a short wall portion inclined from each longitudinal end edge of the top plate portion toward each end edge located at the longitudinal end of the lid, and the top plate A long wall portion that connects both edges in the short direction of the plate portion and the lid, and the shielding member covers the pressure release valve disposed on the top plate portion from the electrode assembly side. And a side wall protruding toward the lid from a pair of edge portions of the shield extending along the longitudinal direction of the lid, and the shield and the top plate in the case And a gas passage partitioned by the pair of side walls, and partitioned by each edge of the shielding portion, each short wall portion, and the pair of long wall portions located near the longitudinal end of the lid body. The gist of the present invention is that a pair of gas inflow portions are provided.

  According to this, when the nail is inserted into the case during the nail penetration test, electrodes of different polarities are short-circuited in the case via the nail. When a short circuit occurs, heat is generated around the short circuit part, and the electrolyte component is decomposed to generate gas. Due to the generation of gas, the pressure in the power storage device increases. When the internal pressure of the case reaches the open pressure of the pressure release valve, the pressure release valve is cleaved and the gas in the case is released out of the case.

  The high-pressure gas generated in the short-circuit portion is directed to the pressure release valve that is cleaved from the end face of the electrode assembly. At this time, a part of the electrode is peeled off by the generated gas. Since the shielding part covers the cleaved pressure release valve from the electrode assembly side, the gas that has flowed out of the electrode assembly collides with the shielding part, and the direction of the gas that has been directed to the pressure relief valve changes and is directed to the pressure relief valve. The gas discharge route becomes longer. As a result, a part of the electrode contained in the gas is prevented from falling from the gas, and a part of the electrode is prevented from scattering from the cleaved pressure release valve to the outside of the case.

  The generated gas collides with the shielding part and then flows into the gas passage from the gas inflow part. By providing the bulging part on the lid, compared to the case without the bulging part, the height of the gas passage partitioned between the shielding part and the opening width of the gas inflow part can be increased, The cross-sectional area of the gas passage and the gas inflow portion can be increased. As a result, the generated gas can be efficiently discharged out of the case from the cleaved pressure release valve, and the case can be prevented from bursting during the nail penetration test.

  In the power storage device, the separation distance a at the shortest distance between the edge of the shielding portion and the short wall portion in the gas inflow portion is opposed to the inner surface of the top plate portion in the gas passage and the inner surface. It may be longer than the separation distance b at the shortest distance from the inner surface of the shielding part.

  The difference in the cross-sectional area of the gas passage and the gas inflow portion is determined by the difference between the separation distances a and b. Since the separation distance a of the gas inflow portion is longer than the separation distance b of the gas passage, the gas inflow portion does not become a restriction. For this reason, a gas passage can be secured by providing a bulging portion, and the generated gas can be efficiently discharged from the cleaved pressure release valve to the outside of the case, and the case can be prevented from bursting during the nail penetration test.

  Further, for the power storage device, a positive electrode terminal and a negative electrode terminal of the power storage device fixed to the lid, and a short-circuit mechanism that short-circuits the positive electrode terminal and the negative electrode terminal when the internal pressure of the case reaches a set pressure. It may be provided on the outer surface of the lid.

  According to this, even in a power storage device including a short-circuit mechanism, there is no short-circuit mechanism in the case, and the electrode assembly can be enlarged so as to approach the lid. On the other hand, the gap between the lid and the electrode assembly becomes narrow, but by providing the bulging portion, a space for arranging the shielding member between the lid and the electrode assembly is secured, and the gas passage is narrow. To avoid becoming.

  The power storage device is a secondary battery.

  According to the present invention, rupture of the case can be suppressed during the nail penetration test.

The perspective view which shows the secondary battery of embodiment. Sectional drawing which shows the secondary battery of embodiment. The expanded sectional view which shows a short circuit apparatus. The perspective view which shows a shielding member. The expanded sectional view which shows a shielding member and a bulging part. (A) is a top view which shows a shielding member and a bulging part from the outer surface side of a cover body, (b) is a top view which shows a shielding member and a bulging part from the inner surface side of a cover body. The fragmentary sectional view which shows the secondary battery at the time of a nail penetration test. Sectional drawing which shows the shielding member of another example. The figure which shows background art.

Hereinafter, an embodiment in which the power storage device is embodied as a secondary battery will be described with reference to FIGS.
As shown in FIG. 1 or 2, the secondary battery 10 as the power storage device includes a case 11. The secondary battery 10 includes an electrode assembly 12 accommodated in a case 11 and an electrolyte solution (not shown). The case 11 includes a rectangular box-shaped case main body 13 having an opening 13 a and a rectangular plate-shaped lid body 14 that closes the opening 13 a of the case main body 13.

  Both the case body 13 and the lid body 14 are made of aluminum. The case main body 13 includes a rectangular plate-like bottom wall 13b, a short side wall 13c having a shape protruding from the short side edge of the bottom wall 13b, and a long side wall 13d having a shape protruding from the long side edge of the bottom wall 13b. The lid body 14 is one surface of the pair of plate surfaces and is located on the outer side of the case 11 and is directed to the outside of the case 11, and the other surface is the inner surface of the case 11. And an inner surface 14a facing the surface. 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 battery.

  Although not described in detail, the electrode assembly 12 includes a plurality of rectangular sheet-like positive electrodes 19 and a plurality of rectangular sheet-like negative electrodes 20. The positive electrode 19 and the negative electrode 20 are electrodes having different polarities. The positive electrode 19 includes a positive electrode metal foil (in this embodiment, an aluminum foil) and a positive electrode active material layer present on both surfaces of the positive electrode metal foil. The negative electrode 20 includes a negative electrode metal foil (a copper foil in the present embodiment) and a negative electrode active material layer present on both surfaces of the negative electrode metal foil.

  The electrode assembly 12 is a laminated type having a layered structure in which separators (not shown) are interposed between a plurality of positive electrodes 19 and a plurality of negative electrodes 20. The electrode assembly 12 includes a positive electrode 19 and a negative electrode 20 that are insulated from each other and stacked. The separator insulates the positive electrode 19 and the negative electrode 20. The stacking direction of the positive electrode 19 and the negative electrode 20 coincides with the short direction of the lid 14 in the case 11.

  The positive electrode 19 has a tab 15 having a shape protruding from a part of one side thereof. The negative electrode 20 has a tab 16 having a shape protruding from a part of one side thereof. The plurality of positive electrode tabs 15 and the plurality of negative electrode tabs 16 do not overlap each other in a state where the positive electrode 19 and the negative electrode 20 are laminated.

  As shown in FIG. 2, the electrode assembly 12 has tab-side end surfaces 12 b from which the tabs 15 and 16 protrude. The tab side end surface 12 b is an end surface of the electrode assembly 12 facing the inner surface 14 a of the lid body 14. The secondary battery 10 includes a positive electrode tab group 17 having a shape protruding from the tab-side end surface 12 b toward the inner surface 14 a of the lid body 14. The positive electrode tab group 17 is configured by collecting and stacking all the positive electrode tabs 15 on one end side in the stacking direction of the electrode assembly 12. The secondary battery 10 includes a negative electrode tab group 18 that protrudes from the tab-side end surface 12 b toward the inner surface 14 a of the lid body 14. The negative electrode tab group 18 is configured by collecting and stacking all the negative electrode tabs 16 on one end side in the stacking direction of the electrode assembly 12.

  The secondary battery 10 includes a positive electrode conductive member 21. The positive electrode conductive member 21 has a rectangular plate shape with the length extending in the longitudinal direction X of the lid body 14. A positive electrode tab group 17 is joined to one end in the longitudinal direction of the positive electrode conductive member 21. A positive electrode terminal 22 is joined to the other end side in the longitudinal direction of the positive electrode conductive member 21. The positive terminal 22 is fixed to the lid body 14.

  The secondary battery 10 includes a negative electrode conductive member 23. The negative electrode conductive member 23 has a rectangular plate shape with the length extending in the longitudinal direction X of the lid body 14. A negative electrode tab group 18 is joined to one end in the longitudinal direction of the negative electrode conductive member 23. A negative electrode terminal 24 is joined to the other end in the longitudinal direction of the negative electrode conductive member 23. The negative terminal 24 is fixed to the lid body 14. The positive electrode conductive member 21 and the negative electrode conductive member 23 are interposed 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.

  The positive electrode conductive member 21 and the negative electrode conductive member 23 are juxtaposed along the surface direction of the lid body 14. The surface direction of the lid body 14 is a direction along the inner surface 14a of the lid body 14. In the present embodiment, the positive electrode conductive member 21 and the negative electrode conductive member 23 are arranged in the longitudinal direction X of the lid body 14 that is one of the surface directions of the lid body 14. Therefore, the parallel direction of the positive electrode conductive member 21 and the negative electrode conductive member 23 is the longitudinal direction X of the lid body 14. The surface direction of the lid body 14 and the direction orthogonal to the longitudinal direction X is the lateral direction Y. The short direction Y of the lid 14 coincides with the stacking direction of the positive electrode 19, the separator and the negative electrode 20.

  The positive electrode terminal 22 penetrates the lid body 14 and a part thereof is exposed outside the case 11. The positive terminal 22 is electrically connected to the lid body 14. The negative electrode terminal 24 penetrates the lid body 14 and a part thereof is exposed outside the case 11. In addition, a ring-shaped first insulating member 25 for insulating from the case 11 is attached to the negative electrode terminal 24.

Next, the short-circuit mechanism 30 provided in the secondary battery 10 will be described.
As shown in FIG. 3, the short-circuit mechanism 30 is disposed on the outer surface 14 b of the lid body 14. The short-circuit mechanism 30 includes a deformation plate 31 and a short-circuit plate 32. The deformable plate 31 is a conductive diaphragm that is formed of a plate material having a constant plate thickness and is circular when viewed in plan. The deformable plate 31 has a shape that protrudes toward the electrode assembly 12 when the internal pressure of the case 11 is lower than a predetermined value. The upper surface 31 a of the deformation plate 31 faces the short-circuit plate 32, and the lower surface 31 c faces the tab-side end surface 12 b of the electrode assembly 12. The deformation plate 31 is fixed to the lid body 14 by joining the outer peripheral end 31 b of the deformation plate 31 to the lid body 14 of the case 11. For this reason, the internal pressure of the case 11 acts on the lower surface 31 c of the deformation plate 31. On the other hand, atmospheric pressure acts on the upper surface 31 a of the deformation plate 31. At least a part of the deformable plate 31 can be deformed upwardly convex (convex toward the short-circuit plate 32).

  The deformation plate 31 is electrically connected to the lid body 14. As described above, the lid body 14 is electrically connected to the positive terminal 22 and insulated from the negative terminal 24. For this reason, the deformation plate 31 is electrically connected to the positive terminal 22 and insulated from the negative terminal 24. The deformable plate 31 may be integrally formed with the lid body 14 of the case 11 or may be welded to the lid body 14 after being molded separately from the lid body 14.

  The short-circuit plate 32 is a metal member and has conductivity. The short-circuit plate 32 is formed in a substantially rectangular shape in plan view, and is disposed above the deformation plate 31. The short-circuit plate 32 has a facing surface 32 a that faces the upper surface 31 a of the deformation plate 31. The short-circuit plate 32 includes a protrusion 33 that protrudes from the facing surface 32 a toward the deformation plate 31. The protrusion 33 is integrally formed with the short-circuit plate 32 by, for example, pressing.

  The short-circuit plate 32 is electrically connected to the negative electrode terminal 24. A first insulating member 25 and a second insulating member 35 are disposed between the short-circuit plate 32 and the lid body 14. The short-circuit plate 32 is supported on the lid body 14 by the first insulating member 25 and the second insulating member 35. The first insulating member 25 insulates the negative electrode terminal 24 from the lid body 14 and insulates one end of the short-circuit plate 32 from the lid body 14. The second insulating member 35 insulates the other end of the short-circuit plate 32 from the lid body 14. For this reason, the short-circuit plate 32 is insulated from the lid body 14. That is, the short-circuit plate 32 is insulated from the positive terminal 22.

  In the present embodiment, the deformable plate 31 is connected to the positive electrode terminal 22 and the short-circuit plate 32 is connected to the negative electrode terminal 24. However, the configuration is not limited thereto. For example, the deformation plate 31 may be connected to the negative terminal 24 and the short-circuit plate 32 may be connected to the positive terminal 22.

  In the short-circuit mechanism 30, when the internal pressure of the case 11 is equal to or lower than the set pressure, the deformable plate 31 is convex downward. As described above, the deformation plate 31 is electrically connected to the positive terminal 22 and insulated from the negative terminal 24. For this reason, an energization path through the short-circuit mechanism 30 is not formed between the positive electrode terminal 22 and the negative electrode terminal 24.

  When the internal pressure of the case 11 increases, the pressure acting on the lower surface 31c of the deformation plate 31 increases. On the other hand, atmospheric pressure acts on the upper surface 31 a of the deformation plate 31. For this reason, when the internal pressure of the case 11 rises and reaches the set pressure, the deformable plate 31 is deformed so as to protrude upward as indicated by a two-dot chain line in FIG. In the deformable plate 31, a portion that is deformed upward and protrudes contacts the protrusion 33 of the short-circuit plate 32. As a result, the deformable plate 31 contacts the short-circuit plate 32 via the protrusion 33. Then, an energization path is formed between the positive electrode terminal 22 and the negative electrode terminal 24 via the deformation plate 31 and the short-circuit plate 32. That is, the positive electrode terminal 22 and the negative electrode terminal 24 are short-circuited. As a result, the current flowing through the electrode assembly 12 can be reduced.

  As shown in FIG. 1 or FIG. 2, the secondary battery 10 includes a bulging portion 37 in the lid body 14. The bulging portion 37 has a shape in which the outer surface 14b of the lid body 14 is convex outward. In other words, the bulging portion 37 has a shape in which the outer surface 14b of the lid body 14 is convex toward the outside of the case 11, and the inner surface 14a of the lid body 14 is recessed toward the outside. The bulging portion 37 is provided at the center in the longitudinal direction X of the lid body 14. The bulging portion 37 includes a flat top plate portion 38 at the tip in the bulging direction from the lid body 14. The top plate portion 38 has a rectangular shape when viewed from the outer surface 14 b side of the lid body 14, and the length of the top plate portion 38 extends in the longitudinal direction X of the lid body 14. The inner surface 38 a of the top plate portion 38 is a surface extending in parallel with the inner surface 14 a of the lid body 14, and the outer surface 38 b of the top plate portion 38 is a surface extending in parallel with the outer surface 14 b of the lid body 14.

  The bulging portion 37 includes short wall portions 39 a that are inclined from both end edges in the longitudinal direction of the top plate portion 38 toward each end edge located at the end in the longitudinal direction of the lid body 14. Further, the bulging portion 37 has a long wall portion 39 b that connects the both ends of the top plate portion 38 in the short direction and the lid body 14. When the secondary battery 10 is viewed from the side of the long side wall 13d, the long wall portion 39b widens toward the outer surface 14b of the lid body 14 from the outer surface 38b of the top plate portion 38.

  The secondary battery 10 includes a pressure release valve 40 in the top plate portion 38 of the bulging portion 37. The pressure release valve 40 is cleaved when the internal pressure of the case 11 reaches an open pressure that is a predetermined pressure. The internal pressure of the case 11 is released to the outside of the case 11 by the cleavage of the pressure release valve 40.

  The release pressure of the pressure release valve 40 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 cracks or breakage can occur. The pressure release valve 40 includes a thin plate-like valve body 41 that is thinner than the plate thickness of the lid body 14. The valve body 41 is located at the bottom of a concave portion 14 c that is recessed from the outside to the inside on the outer surface 14 b that is located outside the case 11, and is formed integrally with the lid body 14. Has been. In a plan view of the lid body 14 as viewed from the outer surface 14 b side, the pressure release valve 40 has a long hole shape with the length extending in the longitudinal direction of the top plate portion 38.

Here, the nail penetration test of the secondary battery 10 will be described.
As shown in FIG. 7, the nail penetration test is performed by inserting a nail into the central portion of the secondary battery 10 in a front view. The separator between the positive electrode 19 and the negative electrode 20 is broken by the nail, and the positive electrode 19 and the negative electrode 20 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. At this time, the internal pressure of the case 11 suddenly increases, the pressure release valve 40 is cleaved, and gas is released from the pressure release valve 40 to the outside of the case 11.

  As shown by the arrow G, the gas rises from the center of the electrode assembly 12 toward the pressure release valve 40. At this time, a part of the positive electrode 19 or the negative electrode 20 is scraped off by the rising gas, and a foreign substance including the scraped electrode or the like may be generated. The foreign matter goes to the pressure release valve 40 together with the gas going to the pressure release valve 40.

The secondary battery 10 includes a shielding member 50 that suppresses foreign matter generated during the nail penetration test from being released from the pressure release valve 40 to the outside of the case 11.
As shown in FIG. 4 or 5, the shielding member 50 is joined to the inner surface 38 a of the top plate portion 38. The shielding member 50 is disposed between the inner surface 38a of the top plate portion 38 and the tab side end surface 12b. The shielding member 50 includes a rectangular plate-shaped shielding part 51.

  As shown in FIG. 5, FIG. 6A, or FIG. 6B, the shielding portion 51 has a rectangular plate shape when viewed from the outer surface 14 b side or the inner surface 14 a of the lid body 14. The shielding part 51 has a shape in which the longitudinal direction extends in the longitudinal direction of the top plate portion 38 (longitudinal direction X of the lid body 14), and the short side extends in the lateral direction of the top plate portion 38 (the lateral direction Y of the lid body 14). is there. The shielding part 51 includes end edges 51c at both ends in the longitudinal direction. Each end edge 51 c is an edge portion of the shielding portion 51 located near the end in the longitudinal direction X of the lid body 14.

  The shielding member 50 includes side walls 52 projecting from the pair of long edges of the shielding part 51 extending along the longitudinal direction X of the lid body 14 toward the lid body 14. On each edge 51 c side of the shielding part 51, the side walls 52 adjacent to each other in the short direction of the shielding part 51 are separated from each other in the short direction of the shielding part 51.

  The shielding member 50 includes a flange 53 supported by a pair of side walls 52 on each edge 51 c side of the shielding part 51. The flange 53 has a rectangular plate shape whose longitudinal direction extends in the short direction Y of the lid body 14, that is, in the short direction of the shielding part 51. When viewed from the outer surface 14 b side or the inner surface 14 a side of the lid body 14, each flange 53 protrudes outward from the end edge 51 c of the shielding portion 51. The pair of flanges 53 are joined to the top plate portion 38 in a state in which the longitudinal direction extends in the short direction Y of the lid body 14 (top plate portion 38). Therefore, the shield member 50 is welded to the top plate portion 38 by welding the pair of flanges 53 to a position between the inner surfaces 38a of the top plate portion 38 and sandwiching the pressure release valve 40 from both sides in the longitudinal direction X of the lid body 14. It is joined.

  The shielding portion 51 includes an inner surface 51 a on the surface facing the inner surface 38 a of the top plate portion 38, and an outer surface 51 b on the surface facing the tab side end surface 12 b of the electrode assembly 12. The outer surface 51 b of the shielding part 51 is located closer to the electrode assembly 12 than the inner surface 14 a of the lid body 14. Further, in the longitudinal direction X of the lid body 14, each side wall 52 of the shielding part 51 is located closer to the pressure release valve 40 than each short wall part 39 a of the bulging part 37.

  As shown in FIGS. 6A and 6B, in the plan view of the secondary battery 10 viewed from the outer surface 14b side or the inner surface 14a side of the lid body 14, the shielding portion 51 is located on the short wall portion 39a. The pressure release valve 40 is covered from the electrode assembly 12 side in a position that overlaps only the top plate portion 38 without overlapping.

  As shown in FIG. 5, the secondary battery 10 includes a gas passage 56 in the case 11. The gas passage 56 is defined by the shielding portion 51, the pair of side walls 52, and the top plate portion 38. The gas passages 56 are open toward both ends in the longitudinal direction X of the lid body 14. The secondary battery 10 includes a gas inflow portion 57 in the case 11. The gas inflow portion 57 is a space defined by each end edge 51c located at the end in the longitudinal direction of the shielding portion 51, each short wall portion 39a, and a part of each of the pair of long wall portions 39b near each end edge 51c. It is. Each gas inflow portion 57 is connected to both ends of the gas passage 56 in the longitudinal direction.

  In the gas inflow part 57, the length of the straight line L1 connecting the end edge 51c of the shielding part 51 and the inner surface of the short wall part 39a with the shortest distance is defined as a separation distance a. On the other hand, in the gas passage 56, if the length of the straight line L2 connecting the inner surface 51a of the shielding part 51 and the inner surface 38a of the top plate part 38 with the shortest distance is the separation distance b, the separation distance a of the gas inflow part 57 described above. Is longer than the separation distance b in the gas passage 56.

  A case in which the bulging portion 37 is not provided on the lid body 14 and the lid body 14 has a flat plate shape is taken as a comparative example, and positions of the inner surface 14a and the outer surface 14b of the lid body 14 of the comparative example are indicated by two-dot chain lines. In the gas passage 56 in this comparative example, if the length of the straight line L3 connecting the inner surface 51a of the shielding part 51 and the inner surface 14a of the lid body 14 with the shortest distance is the separation distance c, the separation distance c of the comparative example is It is shorter than the separation distance a and the separation distance b when the protruding portion 37 is provided.

  The cross-sectional area of the gas passage 56 is determined by the height of the gas passage 56 and the separation distance between the pair of side walls 52 along the short direction Y of the lid body 14 (the short direction of the shielding portion 51). If the distance between the pair of side walls 52 is the same, in the comparative example in which the bulging portion 37 is not provided, the height of the gas passage 56 is reduced, and the flow passage cross-sectional area of the gas passage 56 is reduced. Therefore, by providing the bulging portion 37, the flow path cross-sectional area of the gas passage 56 can be made wider than when the bulging portion 37 is not provided.

  As described above, the cross-sectional area of the gas passage 56 is such that the separation distance b, which is the height of the gas passage 56, and a pair of side walls along the short direction Y of the lid body 14 (short direction of the shielding portion 51). 52 is determined by the separation distance. On the other hand, the flow path cross-sectional area of the gas inflow portion 57 is a separation distance a that is the opening width of the gas inflow portion 57 in the longitudinal direction X of the lid body 14 and a pair of long walls along the short direction Y of the lid body 14. It is determined by the separation distance of the part 39b. If the separation distance between the pair of long wall portions 39b is substantially the same as the separation distance between the pair of side walls 52 of the shielding member 50, the separation distance a is longer than the separation distance b. Larger than the cross-sectional area of the channel. Therefore, the gas inflow portion 57 does not become a restriction of the gas passage 56.

  In addition, the separation distance c of the comparative example is shorter than the separation distance a. That is, by providing the bulging portion 37, the flow passage cross-sectional area of the gas inflow portion 57 is widened, and the gas inflow portion 57 does not become a restriction of the gas passage 56.

Next, the operation of the secondary battery 10 will be described.
Now, as shown in FIG. 7, in order to perform a nail penetration test, gas is generated when a nail is inserted into the central portion of the case 11 when the secondary battery 10 is viewed from the front. The generation of gas causes an increase in the internal pressure of the case 11 in the secondary battery 10. When the internal pressure of the case 11 reaches the open pressure of the pressure release valve 40, the valve body 41 of the pressure release valve 40 is cleaved, and the gas in the case 11 is released to the outside of the case 11.

  As indicated by the arrow G, the high-pressure gas generated around the short-circuit portion rises toward the cleaved pressure release valve 40. Moreover, a part of each electrode is scraped off by the generated gas, and foreign matter is generated. The gas toward the pressure release valve 40 exits the electrode assembly 12 from the tab side end face 12b. Then, after the gas collides with the shielding part 51 of the shielding member 50, the gas changes direction and flows toward the gas inflow part 57. As a result, the gas discharge path toward the pressure release valve 40 becomes longer. Then, after flowing into the gas inflow portion 57, the gas flows through the gas passage 56 and is released from the pressure release valve 40 to the outside of the case 11. On the other hand, since the foreign substance contained in the gas rises as shown by the arrow G and contacts the shielding part 51, the foreign substance is prevented from falling in the direction opposite to the arrow G and being released to the outside of the case 11. Is done.

According to the above embodiment, the following effects can be obtained.
(1) The secondary battery 10 includes a pressure release valve 40 in the top plate portion 38 of the bulging portion 37 and a shielding member 50 disposed inside the bulging portion 37. By providing the bulging portion 37, the height of the gas passage 56 is made higher than when the bulging portion 37 is not provided, the opening width of the gas inflow portion 57 is increased, and the flow path of the gas passage 56 and the gas inflow portion 57 is increased. The cross-sectional area can be increased. For this reason, the generated gas can be efficiently released out of the case 11 from the cleaved pressure release valve 40, and the case 11 can be prevented from bursting during the nail penetration test.

  (2) The secondary battery 10 includes a gas passage 56 and a gas inflow portion 57 partitioned by the bulging portion 37 and the shielding member 50. The separation distance a in the gas inflow portion 57 is longer than the separation distance b in the gas passage 56. By setting the separation distance a and the separation distance b in this way, it is possible to avoid the gas inflow part 57 connected to the gas passage 56 from being throttled while providing the bulging part 37, and to efficiently release the gas to the pressure release valve. 40 can be discharged out of the case 11. Therefore, the rupture of the case 11 can be suppressed during the nail penetration test.

  (3) The secondary battery 10 includes a short-circuit mechanism 30 disposed on the outer surface 14 b of the lid body 14. For this reason, the short-circuit mechanism 30 does not exist in the case 11 of the secondary battery 10, and the electrode assembly 12 can be enlarged so that the tab-side end surface 12 b approaches the inner surface 14 a of the lid body 14. On the other hand, the interval between the inner surface 14a of the lid body 14 and the tab side end surface 12b of the electrode assembly 12 is narrowed, but by providing the bulging portion 37 on the lid body 14, the height of the shielding member 50 is increased. The size is not reduced, and the narrowing of the gas passage 56 is avoided.

  (4) The shielding portion 51 of the shielding member 50 is positioned closer to the electrode assembly 12 than the inner surface 14 a of the lid body 14. For this reason, the position of the edge 51c of the shielding part 51 can be prevented from narrowing the gas inflow part 57.

In addition, you may change the said embodiment as follows.
As shown in FIG. 8, if the bulging part 37 is provided, the separation distance a may be shorter than the separation distance b. When configured in this manner, the flow passage cross-sectional area of the gas inflow portion 57 is smaller than the flow passage cross-sectional area of the gas passage 56, and the gas inflow portion 57 and the gas passage 56 function as a throttle flow passage.

  During the nail penetration test, the high-pressure gas generated around the short-circuit portion rises toward the cleaved pressure release valve 40. Moreover, a part of each electrode is scraped off by the generated gas, and foreign matter is generated. The gas toward the pressure release valve 40 exits the electrode assembly 12 from the tab side end face 12b. Then, after the gas collides with the shielding part 51 of the shielding member 50, the gas changes direction and flows toward the gas inflow part 57. After the gas flows into the gas inflow portion 57, the gas flows through the gas passage 56 and is released from the pressure release valve 40 to the outside of the case 11.

  At this time, since the gas inflow portion 57 and the gas passage 56 function as a throttle channel, for example, the throttle channel can be made longer than when only the gas channel 56 is a throttle channel. As a result, when the gas passes through the gas passage 56 and the gas inflow portion 57, the foreign matter contained in the gas collides with the top plate portion 38, the side wall 52, etc. and falls from the gas. Moreover, the flow rate of gas falls and the foreign material contained in gas falls from gas. As a result, the foreign matter is not released from the pressure release valve 40 to the outside of the case 11 and the discharge of sparks can be suppressed.

The inclination angle of the short wall portion 39a of the bulging portion 37 may be changed as appropriate.
(Circle) you may change suitably the quantity (height) of the bulging part 37 made to protrude from the outer surface 14b of the cover body 14. FIG.

The flange 53 may be located inside the end edge 51 c of the shielding part 51 along the longitudinal direction of the shielding part 51.
In the plan view seen from the inner surface 14a or the outer surface 14b side of the lid body 14, the pressure relief valve 40 may have a shape in which the short side of the pressure relief valve 40 extends in the longitudinal direction of the lid body 14, or It may be a shape. In this case, the shielding part 51 may have a square shape in plan view so that the pressure release valve 40 can be covered with the shielding part 51, or a rectangle in which the short side of the shielding part 51 extends in the longitudinal direction of the lid body 14. It may be a shape.

As long as the bulging portion 37 is provided, the separation distance a and the separation distance b may be the same.
The secondary battery 10 may not include the short-circuit mechanism 30.
○ The short-circuit mechanism may be disposed in the case 11.

(Circle) the structure provided in the state insulated from the cover body 14 may be sufficient as a short circuit mechanism.
The power storage device may be another power storage device such as an electric double layer capacitor.
The secondary battery 10 is a lithium ion secondary battery, but is not limited thereto, and may be another secondary battery such as nickel metal hydride. 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.

Next, technical ideas that can be grasped from the above-described embodiment and other examples will be described below together with their effects.
(1) The short-circuit mechanism is electrically connected to one electrode terminal of the positive electrode terminal and the negative electrode terminal, electrically connected to the deformed plate insulated from the other electrode terminal, and to the other electrode terminal. A power storage device comprising: a short-circuit plate insulated from the one electrode terminal.

  (2) In a plan view of the lid body as viewed from the outer surface side, the pressure release valve has a shape extending in the longitudinal direction of the lid body, and the shielding portion is elongated in the longitudinal direction of the lid body. A power storage device that extends in a rectangular shape.

  a ... separation distance, b ... separation distance, X ... longitudinal direction, 10 ... secondary battery as a power storage device, 11 ... case, 12 ... electrode assembly, 13 ... case body, 13a ... opening, 14 ... lid body, 14 ... outer surface, 19 ... positive electrode, 20 ... negative electrode, 22 ... positive electrode terminal, 24 ... negative electrode terminal, 30 ... short-circuit mechanism, 37 ... bulge portion, 38 ... top plate portion, 38a ... inner surface, 39a ... short wall portion 39b ... long wall part, 40 ... pressure release valve, 50 ... shielding member, 51 ... shielding part, 51a ... inner surface, 51c ... end edge, 52 ... side wall, 56 ... gas passage, 57 ... gas inflow part.

Claims (4)

A rectangular parallelepiped electrode assembly having a layered structure in which electrodes of different polarities are laminated and insulated from each other;
An electrolyte,
A case having a rectangular box-shaped case main body that accommodates the electrode assembly and the electrolytic solution, and a rectangular plate-shaped lid that closes an opening of the case main body;
A pressure release valve that is present in the lid and cleaves when the internal pressure of the case reaches an open pressure, and releases the internal pressure of the case to the outside of the case;
A shielding member that covers the pressure release valve from the electrode assembly side in the case,
The lid includes a bulging portion that bulges into a shape in which the lid is convex toward the outside of the case,
The bulging portion is positioned at the distal end of the lid in the bulging direction and has a rectangular shape extending in the longitudinal direction of the lid, and the top plate portion on which the pressure release valve is disposed; A short wall portion that is inclined from both longitudinal edges of the plate portion toward each edge located at the longitudinal end of the lid, and both lateral edges of the top plate portion in the short direction and the lid. A long wall portion to connect,
The shielding member includes a shielding portion that covers the pressure release valve disposed on the top plate portion from the electrode assembly side, and a pair of edges of the shielding portion that extends along a longitudinal direction of the lid body. And a side wall protruding toward the
In the case, a gas passage defined by the shielding portion, the top plate portion, and the pair of side walls is provided, and each edge of the shielding portion is located near the longitudinal end of the lid. And a pair of gas inflow portions partitioned by the short wall portions and the pair of long wall portions.   The separation distance a at the shortest distance between the edge of the shielding portion and the short wall portion in the gas inflow portion is the inner surface of the top plate portion in the gas passage and the inner surface of the shielding portion facing the inner surface. The power storage device according to claim 1, wherein the power storage device is longer than the separation distance b at the shortest distance between the power storage device and the storage device.   A positive electrode terminal and a negative electrode terminal of the power storage device fixed to the lid, and a short-circuit mechanism for short-circuiting the positive electrode terminal and the negative electrode terminal when the internal pressure of the case reaches a set pressure are provided on the outer surface of the lid. The power storage device according to claim 1.   The power storage device according to any one of claims 1 to 3, wherein the power storage device is a secondary battery.