JP2018137179A - Power storage device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power storage device capable of suppressing a part of an electrode from being scattered through a cleaved pressure release valve while suppressing a case from being ruptured, during a nailing test.SOLUTION: A secondary battery 10 includes a pressure release valve 18 in a lid 14, and the secondary battery 10 also includes a shielding member 60 facing the pressure release valve 18. The shielding member 60 is arranged along a tab side end surface 12b of an electrode assembly 12, includes a shielding portion 61 facing the pressure release valve 18, and also includes a plurality of slits 61c in the shielding portion 61, each of the slits opening toward the inner surface of the lid 14 and the tab side end surface 12b of the electrode assembly 12 and having a longitudinal extending in a lamination direction.SELECTED DRAWING: Figure 4

Description

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

  A vehicle such as an EV (Electric Vehicle) or a PHV (Plug in Hybrid Vehicle) is equipped with a secondary battery such as a lithium ion battery as a power storage device that stores power supplied to an electric motor serving as a prime mover. For example, as described in Patent Document 1, the secondary battery includes an electrode assembly and an electrolytic solution accommodated in a case, and the case body wall portion is configured so that the internal pressure of the case is external to the case. A pressure relief valve is provided for opening.

  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. At this time, the internal pressure of the case suddenly rises and the pressure release valve is ruptured.However, a part of the electrode is scraped by high-pressure gas from the periphery of the short-circuited part toward the pressure release valve, and becomes a foreign substance together with the gas. There is a risk of splashing outside.

  When foreign matter is released out of the case, it can spark. In order to prevent the sparks from being scattered, for example, as shown in FIG. 7, 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 lid 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. Furthermore, the safety protection device 92 has a plurality of through holes 93a that penetrate the baffle plate 93 in the thickness direction.

  Even if a foreign object is generated during the nail penetration test, the foreign object is bounced back by the baffle plate 93. Then, it is suppressed that a foreign material is discharged | emitted out of a case with gas, and scattering of a spark is suppressed. The gas from which foreign substances have been removed is discharged from the pressure relief valve 91 to the outside of the case via the gas flow passages 95 and 96 and the through hole 93a.

Japanese Patent Laid-Open No. 2006-96129

  However, in Patent Document 1, the gas generated around the short-circuit portion during the nail penetration test flows linearly toward the cleaved pressure relief valve 91. For this reason, the gas generated in the vicinity of the short-circuit portion flows toward the baffle plate 93 facing the pressure relief valve 91, and the foreign matter also moves toward the baffle plate 93. At this time, there is a possibility that the foreign matter is clogged in the through hole 93 a of the baffle plate 93. Then, the gas flow toward the pressure relief valve 91 is blocked by the baffle plate 93, the function of releasing the gas to the outside of the case is lowered, and the internal pressure of the case is increased and the case may be ruptured.

  The objective of this invention is providing the electrical storage apparatus which can suppress that a part of electrode scatters from the open pressure release valve, suppressing the burst of a case at the time of a nail penetration test.

  A power storage device for solving the above problems includes an electrode assembly having a layered structure in which electrodes having different polarities are insulated from each other and laminated, an electrolyte, a case containing the electrode assembly and the electrolyte, A pressure release valve that is present on the wall of the case and that is cleaved when the internal pressure of the case reaches an open pressure and opens the internal pressure of the case to the outside of the case; A shield member that is in a state that does not short-circuit different polarities between the inner surface of the wall portion and the end surface of the electrode assembly that faces the inner surface, and that faces the pressure release valve, The electrode assembly includes a shielding portion disposed along the end surface of the electrode assembly and facing the pressure release valve, and opens toward the inner surface of the wall portion and the end surface of the electrode assembly. The length extends to And summarized in that a plurality of slits in the shielding unit.

  According to this, when a nail is stuck in the center of the case when viewed from the front during a 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 internal pressure of the case of the power storage device increases. And when the internal pressure of a case reaches the open pressure of a pressure release valve, a pressure release valve will open. Gas generated in the vicinity of the short-circuit portion passes through the slit and is released from the cleaved pressure release valve to the outside of the case. Further, a part of the electrode is peeled off by the generated gas and becomes a foreign substance. In many cases, the foreign matter is a small piece extending in the surface direction of the electrode when viewed from the outer surface of the lid.

  The slit has a shape in which the length extends in the stacking direction of the electrode assembly, and the length of the slit intersects the length of the foreign matter. For this reason, the both ends of the foreign material in the longitudinal direction come into contact with the portion of the shielding portion that sandwiches the slit from the lateral direction. Therefore, it can suppress that a foreign material is jammed in a slit, and it is suppressed that a foreign material passes a slit. As a result, the flow of gas to the pressure release valve is prevented from being obstructed by the shielding portion, and the foreign matter is moved to the outside of the case while suppressing an excessive increase in the internal pressure of the case and suppressing the case from bursting. Release can be suppressed.

Moreover, about the electrical storage apparatus, the sum total of the opening area of the said slit is more than the opening area of the said pressure release valve.
According to this, the gas generated around the short circuit part flows linearly toward the pressure release valve. For this reason, gas tends to collide with a shielding part. In the shielding part, it is possible to secure an opening area through which the gas passes by the slit, to prevent the gas flow toward the pressure release valve from being hindered by the shielding part, and to avoid an excessive increase in the internal pressure of the case.

Moreover, about the electrical storage apparatus, the dimension to the transversal direction of the said slit is set smaller than 1 mm.
According to this, it can suppress effectively that a foreign material passes a slit.

In the power storage device, the shielding member may include an interval holding portion that rises from the shielding portion toward the wall portion.
According to this, even if a shielding part receives gas pressure from the electrode assembly side, a space | interval holding | maintenance part contacts a wall part and hold | maintains the state which separated the shielding part and wall part. For this reason, even in a configuration in which a shielding member is interposed between the end face of the electrode assembly and the wall portion, a gas flow path toward the pressure release valve is ensured, and gas discharge from the pressure release valve to the outside of the case The function can be maintained.

  ADVANTAGE OF THE INVENTION According to this invention, it can suppress that a part of electrode scatters from the pressure-release valve which broke, suppressing the burst of a case at the time of a nail penetration test.

The disassembled perspective view which shows the secondary battery of embodiment. The perspective view which shows the external appearance of the secondary battery of embodiment. The disassembled perspective view which shows the component of an electrode assembly. (A) is the partially broken plan view which shows the inside of a secondary battery, (b) is an enlarged view which shows the slit of a shielding member. The sectional side view which shows the inside of a secondary battery. The partially broken front view which shows the secondary battery at the time of a nail penetration test. 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 case main body 13 having an opening 13 a and a lid body 14 that closes the opening 13 a of the case main body 13.

  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 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.

  As shown in FIG. 3, the electrode assembly 12 includes a plurality of positive electrodes 21 having a rectangular sheet shape and a plurality of negative electrodes 31 having a rectangular sheet shape. The positive electrode 21 and the negative electrode 31 are electrodes having different polarities. The positive electrode 21 includes a positive metal foil (aluminum foil in the present embodiment) 21a and a positive electrode active material layer 21b present on both surfaces of the positive metal foil 21a. The negative electrode 31 includes a negative electrode metal foil (copper foil in this embodiment) 31a and a negative electrode active material layer 31b present on both surfaces of the negative electrode metal foil 31a.

  The electrode assembly 12 is a laminated type having a layered structure in which separators 24 are interposed between a plurality of positive electrodes 21 and a plurality of negative electrodes 31. The separator 24 insulates the positive electrode 21 and the negative electrode 31. The stacking direction of the positive electrode 21 and the negative electrode 31 is the short direction of the lid 14 in the case 11.

  The positive electrode 21 has a tab 25 having a shape protruding from a part of one side of the positive electrode 21. The negative electrode 31 has a tab 35 having a shape protruding from a part of one side of the negative electrode 31. The plurality of positive electrode tabs 25 and the plurality of negative electrode tabs 35 do not overlap each other in a state where the positive electrode 21 and the negative electrode 31 are laminated.

  As shown in FIG. 1, the electrode assembly 12 has tab-side end surfaces 12 b from which tabs 25 and 35 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 26 having a shape protruding from the tab-side end surface 12b. The positive electrode tab group 26 is configured by collecting and stacking all the positive electrode tabs 25 on one end side in the stacking direction of the electrode assembly 12. The secondary battery 10 includes a negative electrode tab group 36 having a shape protruding from the tab-side end surface 12b. The negative electrode tab group 36 is configured by collecting and stacking all the negative electrode tabs 35 on one end side in the stacking direction of the electrode assembly 12.

  The secondary battery 10 includes a positive electrode conductive member 41. The positive electrode conductive member 41 has a rectangular plate shape with the length extending in the longitudinal direction of the lid body 14. A positive electrode tab group 26 is joined to one end in the longitudinal direction of the positive electrode conductive member 41. A positive electrode terminal 42 is joined to the other end in the longitudinal direction of the positive electrode conductive member 41.

  The secondary battery 10 includes a negative electrode conductive member 51. The negative electrode conductive member 51 is in the shape of a rectangular plate whose length extends in the longitudinal direction of the lid body 14. A negative electrode tab group 36 is joined to one end side in the longitudinal direction of the negative electrode conductive member 51. A negative electrode terminal 52 is joined to the other end side in the longitudinal direction of the negative electrode conductive member 51. The positive electrode conductive member 41 and the negative electrode conductive member 51 are interposed between the inner surface 14a of the lid 14 and the tab side end surface 12b of the electrode assembly 12 facing the inner surface 14a.

  As shown in FIG. 4A, the positive electrode conductive member 41 and the negative electrode conductive member 51 are arranged side by side 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 41 and the negative electrode conductive member 51 are arranged in the longitudinal direction of the lid body 14 which is one of the surface directions of the lid body 14. Therefore, the juxtaposed direction of the positive electrode conductive member 41 and the negative electrode conductive member 51 is also the longitudinal direction X of the tab-side end surface 12 b and also the longitudinal direction of the lid body 14. The direction along the tab side end surface 12b and perpendicular to the longitudinal direction X is the stacking direction Y of the positive electrode 21, the separator 24, and the negative electrode 31, and is the short direction of the lid 14 and the tab side end surface 12b. .

  As shown in FIG. 1, the positive electrode terminal 42 and the negative electrode terminal 52 pass through the lid body 14 and a part thereof is exposed outside the case 11. In addition, ring-shaped insulating members 17 a for insulating from the case 11 are attached to the positive terminal 42 and the negative terminal 52, respectively.

  The secondary battery 10 includes a pressure release valve 18 in a lid body 14 as a wall portion. The pressure release valve 18 is opened 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 18.

  The release pressure of the pressure release valve 18 is set to a pressure at which the case 11 itself or the joint portion between the case body 13 and the lid body 14 can be broken before a crack or breakage can occur. The pressure release valve 18 has a thin plate-like valve body 19 that is thinner than the plate thickness of the lid body 14. The valve body 19 is positioned at the bottom of the recess 20 formed in the outer surface 14 b positioned outside the case 11 out of both surfaces of the lid 14, and is formed integrally with the lid 14.

  The pressure release valve 18 is located closer to the positive electrode terminal 42 than the center of the lid body 14 in the longitudinal direction. Further, the pressure release valve 18 is located at the center of the lid 14 in the short direction. In a plan view of the lid body 14 as viewed from the outer surface 14b, the pressure release valve 18 has a long hole shape.

  As shown in FIG. 1, FIG. 4A, or FIG. 5, the secondary battery 10 includes a shielding member 60. The shielding member 60 is disposed between the positive electrode conductive member 41 and the negative electrode conductive member 51 in the longitudinal direction X of the tab side end surface 12b.

  The shielding member 60 is disposed between the inner surface 14a of the lid body 14 and the tab side end surface 12b, and is placed on the tab side end surface 12b. The shielding member 60 is made of a resin having heat resistance and insulation. For this reason, the shielding member 60 does not short-circuit the positive potential member and the negative potential member in the case 11.

  The shielding member 60 includes a rectangular plate-shaped shielding part 61. The shielding part 61 has a rectangular plate shape when viewed from the outer surface 14 b of the lid body 14. The shielding part 61 has a shape in which the long side extends in the longitudinal direction X of the tab side end face 12 b and the short side extends in the stacking direction Y.

  The shielding member 60 includes a plurality of slits 61 c in the shielding part 61. Each slit 61 c penetrates the shielding part 61 in the thickness direction, and each slit 61 c opens toward the inner surface 14 a of the lid body 14 and the tab side end surface 12 b of the electrode assembly 12. Therefore, each slit 61 c communicates the lid 14 side and the electrode assembly 12 side with the shielding part 61 interposed therebetween. Each slit 61 c extends in the short direction of the shielding portion 61. The plurality of slits 61 c are arranged in the longitudinal direction of the shielding part 61. Therefore, the length of each slit 61 c extends in the stacking direction Y of the positive electrode 21, the negative electrode 31, and the separator 24. Each slit 61c extends in the laminating direction Y so as to extend over the entire lateral direction of the tab-side end surface 12b.

Here, the nail penetration test of the secondary battery 10 will be described.
As shown in FIG. 6, the nail penetration test is performed by inserting a nail into the central portion P in the front view of the electrode assembly 12. The separator 24 between the positive electrode 21 and the negative electrode 31 is broken by the nail, and the positive electrode 21 and the negative electrode 31 are short-circuited in the case 11. When a short circuit occurs, heat is generated in the vicinity of the short circuit part, the electrolyte component is decomposed by the heat generated in the vicinity of the short circuit part, and gas is generated in the case 11. At this time, the internal pressure of the case 11 suddenly increases, the pressure release valve 18 is cleaved, and gas is released from the pressure release valve 18 to the outside of the case 11.

  As shown by the arrow G, the gas rises straight from the center of the electrode assembly 12 toward the pressure relief valve 18. At this time, a part of the positive electrode 21 or the negative electrode 31 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 18 together with the gas going to the pressure release valve 18.

  As shown in FIG. 4B, the foreign substance Z is scraped by the gas force of the positive electrode 21 and the negative electrode 31, and rises toward the pressure release valve 18 together with the gas. Therefore, the foreign matter Z is a small piece having the thickness of the positive electrode 21 or the negative electrode 31 and is long in the surface direction of the positive electrode 21 or the negative electrode 31 (the direction in which one side extends) when viewed from the outer surface 14b of the lid 14. Is formed in a shape extending. Hereinafter, in the foreign material Z, when the secondary battery 10 is viewed from the outer surface 14b of the lid body 14, a direction along the longitudinal direction X of the tab side end surface 12b is defined as a longitudinal direction V.

  The slit width W, which is the dimension in the short direction of the slit 61c, is set in view of the foreign substance size S, which is the dimension in the longitudinal direction V of the foreign substance Z. The slit width W is set smaller than the minimum size of the foreign matter Z that can be generated. The minimum value of the foreign substance size S is assumed to be 1 mm, and in this embodiment, the slit width W is set to a value smaller than 1 mm.

  The longitudinal direction of the slit 61 c extends over the entire short direction of the shielding part 61. And the opening area of each slit 61c and the number of the slits 61c are set so that the sum total of the opening area of the slit 61c may become larger than the sum total of the opening area formed at the time of cleavage of the pressure release valve 18.

  As shown in FIG. 4A or 5, the shielding member 60 includes first ribs 62 having a shape erected from the pair of long edge portions of the shielding portion 61 toward the lid body 14. The first rib 62 has a shape extending in the longitudinal direction X of the tab-side end surface 12 b and the longitudinal direction of the lid body 14. The shielding member 60 includes a second rib 63. The second rib 63 has a shape erected from the short edge portion close to the positive electrode conductive member 41 toward the lid body 14 among the pair of short edge portions of the shielding portion 61. The pair of first ribs 62 and second ribs 63 are connected to each other.

  The outer surface of the second rib 63 can be in contact with one end surface in the longitudinal direction of the positive electrode conductive member 41. Further, the end surface of the shielding portion 61 can contact the side surface of the negative electrode tab group 36. When the shielding member 60 moves slightly in the longitudinal direction X of the lid body 14 and the tab-side end surface 12b, it quickly contacts the positive electrode conductive member 41 or the tab group 36 of the negative electrode. For this reason, as for the shielding member 60, the movement to the longitudinal direction X of the cover body 14 and the tab side end surface 12b is controlled.

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

  There is a shielding member 60 between the positive electrode conductive member 41 and the negative electrode conductive member 51 in the longitudinal direction X of the lid body 14 and the tab side end surface 12b. A portion that is a central portion in the longitudinal direction X of the lid body 14 and the tab side end surface 12b and is surrounded by the positive electrode conductive member 41, the negative electrode conductive member 51, and the pair of long side walls 13d is defined as a covering region H. This covering region H is covered with a shielding member 60. A direction in which a straight line connecting the inner surface 14a of the lid body 14 and the bottom surface of the case main body 13 with the shortest distance is defined as a height direction. In the shielding member 60, a surface of the shielding part 61 placed on the tab side end surface 12b is an outer surface 61a, and a surface facing the inner surface 14a of the lid body 14 is an inner surface 61e.

  As shown in FIG. 5, in the shielding member 60, among the dimensions along the standing direction of the first rib 62 from the shielding part 61, the dimension of the first rib 62 from the outer surface 61a of the shielding part 61 is the standing distance H1. And In the shielding member 60, the dimension from the outer surface 61a of the shielding part 61 among the dimensions along the standing direction of the second rib 63 from the shielding part 61 is defined as the standing distance H2. The standing distance H <b> 2 of the second rib 63 is shorter than the standing distance H <b> 1 of the first rib 62. The protruding end of the first rib 62 from the shielding portion 61 is in a position where it substantially contacts the inner surface 14 a of the lid body 14. On the other hand, the protruding end of the second rib 63 from the shielding portion 61 is separated from the inner surface 14 a of the lid body 14. This is to secure a flow path for the gas generated during the nail penetration test for the secondary battery 10 to flow from the positive electrode conductive member 41 side toward the pressure release valve 18. Note that the protruding end of the second rib 63 from the shielding portion 61 is located closer to the lid body 14 than the positive electrode conductive member 41. That is, the position of the protruding end of the second rib 63 is at a position beyond the positive electrode conductive member 41 closer to the lid body 14.

  As shown in FIG. 4A, in the shielding member 60 placed on the tab-side end surface 12b, the pair of first ribs 62 cover the pressure release valve 18 on the inner surface 14a of the lid body 14. It is possible to contact the outside of the pressure release valve 18 in the short direction of the body 14. The second rib 63 is located on the outer side closer to the positive electrode conductive member 41 than the pressure release valve 18 in the longitudinal direction of the lid body 14. Therefore, the 1st rib 62 and the 2nd rib 63 exist in the position which does not overlap with the pressure release valve 18 seeing the cover body 14 from the outer surface 14b. When the secondary battery 10 vibrates or the electrode assembly 12 moves toward the lid body 14, the shielding member 60 also moves toward the lid body 14, and the first rib 62 is formed on the inner surface 14 a of the lid body 14. Contact. The shielding part 61 and the lid body 14 are separated by this contact. Therefore, in the present embodiment, the first rib 62 constitutes the interval holding portion of the shielding member 60.

Next, the operation of the secondary battery 10 will be described.
Now, as shown in FIG. 6, in order to perform a nail penetration test, gas is generated when the nail is inserted into the central portion P 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 18, the valve body 19 of the pressure release valve 18 is cleaved and the gas in the case 11 is released to the outside of the case 11.

  As shown by the arrow G, the high-pressure gas generated around the short-circuit portion rises straight toward the cleaved pressure release valve 18. In addition, the electrodes 21 and 31 are partly scraped off by the generated gas, and the foreign matter Z is generated. The gas toward the pressure release valve 18 exits the electrode assembly 12 from the tab side end face 12b. Then, the gas passes through the slit 61 c and is released from the cleaved pressure release valve 18 to the outside of the case 11.

  On the other hand, as shown in FIG. 4B, the foreign substance Z contained in the gas contacts both ends of the longitudinal direction V with the portion sandwiching the slit 61c in the shielding part 61 from the short side direction. For this reason, the foreign material Z falls and is prevented from passing through the slit 61c.

According to the above embodiment, the following effects can be obtained.
(1) The shielding member 60 includes a plurality of slits 61c in the shielding part 61 facing the tab-side end surface 12b, and the length of the slit 61c extends in the stacking direction Y. For this reason, at the time of a nail penetration test, the both ends of the longitudinal direction V of the foreign material Z can be made to contact the part which pinches | interposes the slit 61c in the shielding part 61 in a transversal direction. As a result, the shielding member 60 can prevent the foreign matter Z contained in the gas from falling into the case 11 and clogging the foreign matter Z into the slit 61c.

  Further, since the gas passes through the slit 61c, it is possible to prevent the gas flow toward the pressure release valve 18 from being blocked by the shielding member 60. As a result, even if the shielding member 60 is disposed, the internal pressure of the case 11 can be suppressed from rising excessively, and the case 11 can be prevented from bursting.

  (2) The sum total of the opening areas of the slits 61 c in the shielding part 61 is equal to or larger than the opening area of the cleaved pressure release valve 18. During the nail penetration test, the gas generated in the electrode assembly 12 is directed to the shielding part 61. However, an opening area through which the gas passes is secured in the shielding part 61, and the gas flow toward the pressure release valve 18 is prevented from flowing through the shielding part 61. Can be suppressed, and an excessive increase in the internal pressure of the case 11 can be avoided.

(3) The dimension of the slit 61c in the short direction is set to be smaller than 1 mm which is the minimum size of the foreign matter Z. For this reason, it can suppress that the foreign material Z passes the slit 61c.
(4) The shielding member 60 includes a first rib 62. The 1st rib 62 contacts the inner surface 14a of the cover body 14, maintains the state which separated the shielding part 61 and the cover body 14, and maintains the space | interval of both surfaces. For this reason, even if it is the structure by which the shielding part 61 is arrange | positioned between the tab side end surface 12b and the inner surface 14a of the cover body 14, the gas flow path is ensured and it goes out of the case 11 from the pressure release valve 18. The gas discharge function can be maintained.

(5) The shielding member 60 is made of heat resistant resin. For this reason, it is possible to suppress the shielding member 60 from being melted by the high-temperature gas generated during the nail penetration test.
(6) The shielding member 60 includes a pair of first ribs 62 that rise from the shielding part 61. For this reason, even if the secondary battery 10 vibrates and the electrode assembly 12 moves toward the lid 14, the shielding member 60 moves toward the lid 14, and the first rib 62 contacts the lid 14. . For this reason, it can avoid that the electrode assembly 12 collides with the cover body 14 with the shielding member 60, and can suppress that the electrode assembly 12 is damaged.

  (7) The tab 25 of the positive electrode 21 is a part of the positive metal foil 21a, and the tab 35 of the negative electrode 31 is a part of the negative metal foil 31a. Therefore, when the positive electrode 21 and the negative electrode 31 are stacked, the shielding member 60 is provided between the tab group 26 in which the tabs 25 of the positive electrode 21 are stacked and the tab group 36 in which the tabs 35 of the negative electrode 31 are stacked. Space can be secured. For example, unlike the case where a tab is provided separately for each electrode 21, 31, the size of the space between the tabs does not vary, and the shielding member 60 cannot be disposed.

  (8) The outer surface of the second rib 63 can contact one end surface of the positive electrode conductive member 41 in the longitudinal direction. Further, the end surface of the shielding portion 61 can contact the side surface of the tab group 36 of the negative electrode in the bent state. For this reason, the movement of the shielding member 60 in the longitudinal direction X of the tab-side end surface 12b can be regulated by the positive electrode conductive member 41 and the negative electrode tab group 36. Therefore, the arrangement in which the slit 61c faces the pressure release valve 18 can be maintained.

In addition, you may change the said embodiment as follows.
The slit width W of the slit 61c may be 1 mm.
The shielding member 60 may have a shape in which the second rib 63 is provided on both short edges of the shielding part 61.

The shielding member 60 may have a shape in which the second rib 63 is provided not on the positive electrode conductive member 41 side but on the short edge portion on the negative electrode conductive member 51 side.
○ Although the first rib 62 is embodied as the interval holding portion, a rod-like shape standing from four corners of the shielding portion 61 may be used.

The rigidity of the first rib 62 and the second rib 63 may be increased by increasing the thickness.
O The thickness of the shielding part 61 may be increased to increase the rigidity of the shielding part 61. When comprised in this way, even if it is the structure which has the slit 61c in the shielding part 61, it can suppress that the shielding part 61 is damaged with the gas generate | occur | produced at the time of a nail penetration test.

The shielding member 60 may have a shape including a plurality of gas through holes that penetrate the second rib 63 in the plate thickness direction.
The shielding member 60 may include a reinforcing rib connected to the shielding part 61 and the first rib 62 or a reinforcing rib connected to the shielding part 61 and the second rib 63.

The pair of first ribs 62 of the shielding member 60 may not be provided upright from each long edge portion of the shielding part 61.
The shielding member 60 made of resin may not be placed on the tab side end surface 12b but may be joined to the inner surface 14a of the lid body 14 or other members by adhesion or welding.

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

The 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, the technical idea that can be grasped from the above embodiment and other examples will be described below.
(1) The power storage device, wherein the slit extends to the entirety of the shielding portion along the stacking direction.

  Y ... stacking direction, Z ... foreign material, 10 ... secondary battery as power storage device, 11 ... case, 12 ... electrode assembly, 12b ... end face on the tab side as end face, 14 ... lid on wall part, 14a ... inner face , 18 ... pressure release valve, 21 ... positive electrode as electrode, 31 ... negative electrode as electrode, 60 ... shielding member, 61 ... shielding part, 61c ... slit, 62 ... first rib as interval holding part.

Claims (4)

An electrode assembly having a layered structure in which electrodes of different polarities are laminated and insulated from each other;
An electrolyte,
A case containing the electrode assembly and the electrolyte;
A pressure release valve that is present on the wall of the case and that is cleaved when the internal pressure of the case reaches an open pressure and opens the internal pressure of the case to the outside of the case; ,
A shield member that is present in a state in which different polarities are not short-circuited between the inner surface of the wall portion and the end surface of the electrode assembly facing the inner surface, and that faces the pressure release valve;
The shielding member is disposed along the end surface of the electrode assembly and includes a shielding portion facing the pressure release valve, and opens toward the inner surface of the wall portion and the end surface of the electrode assembly, A power storage device comprising a plurality of slits extending in a direction in which electrodes are stacked in the shielding portion.   The power storage device according to claim 1, wherein a total sum of opening areas of the slits is equal to or larger than an opening area of the pressure release valve.   The power storage device according to claim 1 or 2, wherein a dimension of the slit in a short direction is set to be smaller than 1 mm.   The power storage device according to any one of claims 1 to 3, wherein the shielding member includes an interval holding unit that rises from the shielding unit toward the wall unit.

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