JP2018037225A - Power storage device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power storage device capable of inhibiting a part of an electrode from scattering from a cleaved pressure release valve at the time of a nailing time.SOLUTION: A secondary battery 10 equipped with a pressure release valve 18 has exhaust passages 51. The exhaust passage 51 penetrates through a plurality of thickness adjusting members 50 in the lamination direction and is formed by laminating a passage formation part 50f extending in a plane direction of the thickness adjusting member 50. An exhaust port 51a of the exhaust passage 51 is opened toward a position located in the outer side than the pressure release valve 18, out of a position along an inner surface 14c of a lid body 14.SELECTED DRAWING: Figure 7

Description

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

  A vehicle such as an EV (Electric Vehicle) or a PHV (Plug in Hybrid Vehicle) is equipped with a secondary battery such as a lithium ion battery as a power storage device that stores power supplied to an electric motor serving as a prime mover. For example, as described in Patent Document 1, the secondary battery includes an electrode assembly and an electrolytic solution housed in a case, and a pressure release valve that releases the pressure inside the case to the outside of the case on the wall surface of the case. Is provided.

Japanese Patent No. 4881409

  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.

  An object of the present invention is to provide a power storage device that can suppress a part of an electrode from being scattered from a cleaved pressure release valve during a nail penetration test.

  A power storage device for solving the above problems includes an electrode assembly configured in layers with electrodes having different polarities insulated by a separator, an electrolytic solution, and a case for housing the electrode assembly and the electrolytic solution. And at least one sheet member stacked on the electrode assembly along the stacking direction of the electrodes, and a wall provided in the case, and is cleaved when the pressure in the case reaches an open pressure. A pressure release valve for releasing the pressure inside the case to the outside of the case, wherein the sheet member penetrates or dents in the stacking direction and forms a passage extending in the surface direction of the sheet member And a downstream end of the exhaust passage in the gas flow direction in the position along the surface direction of the wall portion, the pressure end of the exhaust passage is formed of the passage forming portion of the at least one sheet member. Than the open valve towards the outside position and summarized in that open.

  According to this, when the nail is inserted into the power storage device during the nail penetration test, electrodes having 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 gas generated in the short-circuit portion flows along the stacking direction toward the exhaust passage that is a large space, and flows into the exhaust passage. Then, the gas flows through the exhaust passage and flows toward the downstream end of the exhaust passage. The downstream end of the exhaust passage is outside the pressure release valve in the position along the surface direction of the wall portion, and does not open toward the pressure release valve. For this reason, the gas released from the downstream end of the exhaust passage further flows toward the pressure release valve. That is, the gas flows around the pressure release valve. Therefore, compared with the case where the gas generated in the short circuit part flows directly into the pressure release valve without bypassing the pressure release valve, the gas discharge path from the short circuit part to the pressure release valve can be lengthened. As a result, it is possible to suppress a part of the electrode from dropping from the gas on the way to the pressure release valve, and a part of the electrode from scattering from the cleaved pressure release valve to the outside of the case.

In the power storage device, it is preferable that there are a plurality of exhaust passages.
According to this, the gas generated in the short circuit part can be dispersed in the plurality of exhaust passages. Therefore, for example, the momentum of the gas released from the downstream end of the exhaust passage can be weakened as compared with the case of using a single exhaust passage.

In addition, the power storage device includes a shielding portion that is interposed between an inner surface of the wall portion and an end surface of the electrode assembly facing the inner surface and covers the pressure release valve from the electrode assembly side.
According to this, some of the gas generated in the short circuit part does not flow into the exhaust passage and rises straight in the electrode assembly toward the pressure release valve. By causing the gas to collide with the shielding portion, the direction of the gas can be changed, and the gas discharge path toward the pressure release valve can be lengthened. As a result, both of the exhaust passage and the shielding portion allow a part of the electrode contained in the gas to fall more from the gas, and the amount of the part of the electrode scattered out of the case from the cleaved pressure release valve can be reduced.

Moreover, about the electrical storage apparatus, the downstream end of the gas passage direction in the exhaust passage opens toward a position outside the shielding portion among positions along the surface direction of the wall portion.
According to this, since the shielding part is shaped to cover the pressure relief valve, the downstream end of the exhaust passage outside the shielding part is located further away from the pressure relief valve along the surface direction of the wall part. It will be in. For this reason, the gas discharge path | route of the gas which flows detouring a shielding part can be made longer. As a result, it is possible to suppress a part of the electrode from dropping from the gas on the way to the pressure release valve, and a part of the electrode from scattering from the cleaved pressure release valve to the outside of the case.

  The power storage device is a secondary battery.

  ADVANTAGE OF THE INVENTION According to this invention, it can suppress that a part of electrode scatters from the pressure release valve which broke 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 an electrode assembly and a thickness adjustment member. The perspective view which shows the electrode assembly integrated with the shielding member and the thickness adjustment member. Sectional drawing which shows the inside of a secondary battery. The fragmentary sectional view which shows a nail penetration test. The fragmentary sectional view which shows the secondary battery of the state which the pressure relief valve opened. The perspective view which shows another example of a secondary battery.

Hereinafter, an embodiment in which the power storage device is embodied as a secondary battery will be described with reference to FIGS.
As shown in FIGS. 1 and 2, the secondary battery 10 as the power storage device includes a 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 is a lithium ion secondary battery, and has a metal case 11 that constitutes the outline thereof. The case 11 includes a case main body 13 having an opening 13 a and a lid body 14 that closes the opening 13 a of the case main body 13. The lid body 14 has a rectangular shape in plan view.

  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 secondary battery 10 includes an insulating film 15 that insulates the electrode assembly 12 from the case body 13. 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.

  The secondary battery 10 includes a pressure release valve 18 in the lid body 14. The pressure release valve 18 is located at the center in the longitudinal direction of the lid body 14. Further, the pressure release valve 18 is located at the center of the lid 14 in the short direction. The pressure release valve 18 has a long hole shape when the lid 14 is viewed from the outer surface 14b. In the present embodiment, the lid body 14 constitutes a wall portion of the case 11. The pressure release valve 18 is cleaved when the pressure in the case 11 reaches an open pressure that is a predetermined pressure. The pressure in the case 11 is released outside 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 20 a that is thinner than the plate thickness of the lid body 14. The valve body 20 a is located at the bottom of the recess 20 that is recessed in the outer surface 14 b of the lid body 14, and is molded integrally with the lid body 14. The pressure release valve 18 includes a cleavage groove 20b that facilitates the cleavage of the valve body 20a.

  As shown in FIG. 3, the electrode assembly 12 includes a rectangular sheet-like positive electrode 21 and a rectangular sheet-like negative electrode 22, and is made of resin and is porous so that ions related to electrical conduction (lithium ions) can pass therethrough. And a separator 23 formed of a material film. The direction in which the positive electrode 21, the negative electrode 22, and the separator 23 are stacked is defined as a stacking direction.

  The positive electrode 21 includes a rectangular positive electrode metal foil (aluminum foil in this embodiment) 21a and a rectangular positive electrode active material layer 21b provided on both surfaces (surfaces) of the positive electrode metal foil 21a. . The positive electrode 21 includes a first side 21c on one long side. The positive electrode 21 includes a positive electrode current collecting tab 24 having a shape protruding from a part of the first side 21c. The positive electrode 21 includes a second side 21d on the long side opposite to the first side 21c. Further, the positive electrode 21 includes a third side 21e on a short side connecting one end of the first side 21c and one end of the second side 21d, and the other end of the first side 21c and the second side 21d. A fourth side 21f is provided on the short side connecting the other end of the second side.

  The negative electrode 22 has a rectangular negative electrode metal foil (copper foil in this embodiment) 22a and a rectangular negative electrode active material layer 22b provided on both surfaces (surfaces) of the negative electrode metal foil 22a. . The negative electrode 22 includes a first side 22c on one long side. The negative electrode 22 includes a negative electrode current collecting tab 25 having a shape protruding from a part of the first side 22c. The negative electrode 22 includes a second side 22d on the long side opposite to the first side 22c. Further, the negative electrode 22 includes a third side 22e on a short side connecting one end of the first side 22c and one end of the second side 22d, and the other end of the first side 22c and the second side 22d. A fourth side 22f is provided on the short side connecting the other ends of the second side 22f.

  As shown in FIG. 1, the electrode assembly 12 has rectangular end faces 44 on both sides in the stacking direction, and each end face 44 is constituted by a negative electrode 22. The electrode assembly 12 includes a first side 21c of the positive electrode 21, a first side 22c of the negative electrode 22, and a tab side end face 36 in which one side of the separator 23 along the first sides 21c and 22c is gathered. Have The electrode assembly 12 includes a second side 21d of the positive electrode 21, a second side 22d of the negative electrode 22, and a bottom surface 37 on which one side of the separator 23 along the second sides 21d and 22d gathers. The electrode assembly 12 has a side surface 38 on a surface excluding the tab-side end surface 36 and the bottom surface 37 among the four surfaces connected to the end surface 44. The one side surface 38 of the electrode assembly 12 is formed by gathering the third side 21e of the positive electrode 21, the third side 22e of the negative electrode 22, and one side of the separator 23 along the third sides 21e and 22e. Has been. The other side surface 38 of the electrode assembly 12 is formed by gathering the fourth side 21f of the positive electrode 21, the fourth side 22f of the negative electrode 22, and one side of the separator 23 along these fourth sides 21f and 22f. Has been.

  As shown in FIGS. 1 and 4, the positive electrode 21, the negative electrode 22, and the separator 23 are arranged such that the positive electrode current collecting tabs 24 are arranged in a line along the stacking direction and do not overlap with the positive electrode current collecting tabs 24. The negative electrode current collecting tabs 25 are stacked at the position so as to be arranged in a line along the stacking direction. The positive electrode current collecting tab 24 and the negative electrode current collecting tab 25 are positioned on the tab side end surface 36 of the electrode assembly 12. On the tab side end surface 36, each positive electrode current collecting tab 24 and each negative electrode current collecting tab 25 are bent in a state of being collected (bundled) within a range from one end to the other end in the stacking direction of the electrode assembly 12. ing. Each positive current collecting tab 24 is electrically connected by welding a portion where each positive current collecting tab 24 overlaps, and a positive electrode conductive member 26 is connected to the positive current collecting tab 24. A positive electrode terminal 27 for taking out electricity from the electrode assembly 12 is connected to the positive electrode conductive member 26.

  Similarly, the negative electrode current collecting tabs 25 are electrically connected by welding the portions where the negative electrode current collecting tabs 25 are overlapped, and the negative electrode conductive member 28 is connected to the negative electrode current collecting tabs 25. A negative electrode terminal 29 for taking out electricity from the electrode assembly 12 is connected to the negative electrode conductive member 28. The positive electrode terminal 27 and the negative electrode terminal 29 penetrate the lid body 14 and protrude out of the case 11, and the positive electrode terminal 27 and the negative electrode terminal 29 are insulated from the lid body 14 by the insulating ring 14a.

  The secondary battery 10 includes a shielding member 60. The shielding member 60 is disposed between the positive electrode conductive member 26 and the negative electrode conductive member 28 in the longitudinal direction of the lid body 14. Further, the shielding member 60 is disposed between the inner surface 14 c of the lid body 14 and the tab side end surface 36 and is placed on the tab side end surface 36. The shielding member 60 is made of a synthetic resin, more preferably a heat-resistant resin, for example, a polyimide resin. 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 portion 61 is interposed between the inner surface 14 c of the lid body 14 and the tab side end surface 36 of the electrode assembly 12. The shielding member 60 includes first ribs 62 having a shape erected from the pair of edges of the shielding portion 61 extending in the longitudinal direction of the lid body 14 toward the lid body 14. The first rib 62 has a shape that extends in 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 edge closer to the negative electrode conductive member 28 toward the lid body 14 out of the pair of edge portions facing the longitudinal direction of the lid body 14 in 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 contact one end surface of the negative electrode conductive member 28 in the longitudinal direction. Further, the edge portion of the shielding portion 61 can contact the side surface of the tab group in which the positive electrode current collecting tabs 24 are collected. When the shielding member 60 moves slightly in the longitudinal direction of the lid body 14, it immediately comes into contact with the tab group in which the negative electrode conductive member 28 or the positive electrode current collecting tab 24 is collected. For this reason, as for the shielding member 60, the movement to the longitudinal direction of the cover body 14 is controlled.

  The outer surface of one first 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, it quickly comes into contact with any of the long side walls 13 d. For this reason, as for the shielding member 60, the movement to the transversal direction of the cover body 14 is controlled. Therefore, the movement of the shielding member 60 in any direction along the tab-side end surface 36 is restricted.

  A shielding member 60 exists between the positive electrode conductive member 26 and the negative electrode conductive member 28 in the longitudinal direction of the lid body 14. A portion that is a central portion in the longitudinal direction of the tab-side end surface 36 and is surrounded by the positive electrode conductive member 26, the negative electrode conductive member 28, and the pair of long side walls 13 d 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 14c 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 placed on the tab side end surface 36 in the shielding part 61 is defined as an outer surface 61 a.

  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. This is to secure a flow path for the gas flowing from the negative electrode conductive member 28 side toward the pressure release valve 18.

  In the shielding member 60 placed on the tab-side end surface 36, the pair of first ribs 62 is located in the short direction of the lid body 14 in a place surrounding the pressure release valve 18 at a position along the inner surface 14 c of the lid body 14. It is possible to contact the outside of the pressure release valve 18. The second rib 63 is located closer to the negative electrode conductive member 28 of the pressure release valve 18 in the longitudinal direction of the lid body 14. When the shielding member 60 moves toward the lid body 14, the first rib 62 contacts the inner surface 14 c of the lid body 14. The shielding part 61 and the lid body 14 are separated by this contact. Therefore, the shielding part 61 of the shielding member 60 covers the entire pressure release valve 18 from the electrode assembly 12 side.

  In the case main body 13, when the shortest distance between the insulating films 15 of the pair of long side walls 13d facing each other with the electrode assembly 12 interposed therebetween is the inner dimension of the case main body 13, the length of the electrode assembly 12 in the stacking direction is as follows. It is slightly smaller than the inner dimension of the main body 13. This is because, when a predetermined number of positive electrodes 21, negative electrodes 22, and separators 23 are stacked, the electrode assembly 12 can be accommodated in the case 11 even if the actual thickness takes the maximum manufacturing tolerance. , Because each thickness is set.

  As shown in FIG. 1 or FIG. 4, the thickness adjustment as a sheet member is made between both end faces 44 of the electrode assembly 12 and the long side wall 13 d (insulating film 15) as a side wall facing each end face 44. A member 50 is interposed. The thickness adjusting member 50 is a resin film having a predetermined thickness. A plurality of thickness adjusting members 50 are stacked corresponding to the length of the electrode assembly 12 in the stacking direction. That is, the thickness adjusting member 50 is stacked on the electrode assembly 12 along the stacking direction of the positive electrode 21 and the negative electrode 22.

  In the electrode assembly 12, a large number of positive electrodes 21, negative electrodes 22, separators 23, and a plurality of thickness adjusting members 50 are fixed to each other by a plurality of holding tapes 45. Then, by using the thickness adjusting member 50, the length in the stacking direction in which the electrode assembly 12 and the thickness adjusting member 50 are combined is adjusted within a predetermined value range.

  As shown in FIG. 3, each thickness adjusting member 50 has a shape along the outer shape of the separator 23. The thickness adjusting member 50 includes a first side 50 a along the first side 21 c of the positive electrode 21 and the first side 22 c of the negative electrode 22, and the second side 21 d of the positive electrode 21 and the negative electrode 22. The second side 50b is provided along the second side 22d. The thickness adjusting member 50 includes a third side 21e along the third side 21e of the positive electrode 21 and a third side 22e along the negative electrode 22, and a fourth side 21f of the positive electrode 21; A fourth side 50 d is provided along the fourth side 22 f of the negative electrode 22. The first side 50 a of the thickness adjusting member 50 exists on a surface along the tab-side end surface 36 and faces the lid body 14.

  As shown in FIG. 1, the thickness adjusting member 50 includes two passage forming portions 50f. The passage forming portion 50 f has a shape that penetrates the thickness adjusting member 50 in the thickness direction and extends in the surface direction of the thickness adjusting member 50. One end portion of each passage forming portion 50 f opens near the end portion in the longitudinal direction of the first side 50 a, and the other end portion is located at the center portion of the thickness adjusting member 50. Each passage forming portion 50f has a shape extending straight from the one end portion (first side 50a) toward the other end portion (center portion) with a constant width.

  As shown in FIG. 4, the secondary battery 10 includes two exhaust passages 51 formed by overlapping a plurality of passage formation portions 50 f in the stacking direction, and each exhaust passage 51 includes a plurality of thickness adjusting members 50. The shape penetrates in the thickness direction and extends in the surface direction of the thickness adjusting member 50. That is, each exhaust passage 51 has a shape that penetrates a plurality of thickness adjusting members 50 in the stacking direction. When the electrode assembly 12 is viewed from the stacking direction, the two exhaust passages 51 form a shape close to a V shape.

  As shown in FIG. 5, each exhaust passage 51 includes an exhaust port 51 a at one end located on the first side 50 a of the thickness adjusting member 50. Each exhaust port 51 a is opened at the upper end surface (tab side end surface 36) of the electrode assembly 12. Each exhaust passage 51 includes an inflow port 51 b located at the center of the electrode assembly 12. Each inflow port 51 b opens at the center of the end face 44 of the electrode assembly 12. Since the central part of the end surface 44 of the electrode assembly 12 is also the central part of the positive electrode 21 and the negative electrode 22, the inlet 51 b of each exhaust passage 51 is opened to the central part of the positive electrode 21 and the negative electrode 22. Will be.

  The gas generated when the electrode assembly 12 is short-circuited flows into each exhaust passage 51. Since the gas rises, the exhaust port 51 a as the downstream end in the gas flow direction G in each exhaust passage 51 opens at the tab side end surface 36 that is the upper end surface of the electrode assembly 12. The exhaust port 51 a of the exhaust passage 51 opens toward a position outside the pressure release valve 18 along the longitudinal direction of the lid body 14 among positions along the inner surface 14 c of the lid body 14.

  In the present embodiment, the exhaust port 51 a of each exhaust passage 51 opens at a position outside the tabs 24, 25 along the longitudinal direction of the lid body 14, that is, a position outside the shielding member 60. ing. Therefore, the exhaust port 51 a of each exhaust passage 51 does not open toward the pressure release valve 18.

  In addition, the inflow port 51 b as the upstream end in the gas flow direction G in each exhaust passage 51 is open at the center of the end surface 44 of the electrode assembly 12 that is the center of the positive electrode 21 and the negative electrode 22.

  In the secondary battery 10, since the thickness adjusting member 50 is interposed between both end surfaces 44 of the electrode assembly 12 and the long side walls 13 d, the exhaust passage 51 is connected to the end surface of the electrode assembly 12. 44 and the long side wall 13d.

Next, the operation of the secondary battery 10 will be described.
As shown in FIG. 6, in order to perform a nail penetration test, when the nail F is inserted into the central portion of one of the long side walls 13d, the nail F is inserted into the central portion of the end face 44 of the electrode assembly 12, The positive electrode 21, the negative electrode 22, and the central part of the separator 23 are stuck. At this time, the nail F is stuck in the upstream end of the gas passage direction in the exhaust passage 51, that is, in the vicinity of the inflow port 51b. Then, the separator 23 between the positive electrode 21 and the negative electrode 22 is broken or melted via the nail F, and the positive electrode 21 and the negative electrode 22 are short-circuited in the case 11.

  As shown in FIG. 7, when a short circuit occurs in the electrode assembly 12, heat is generated around the short circuit part, and the pressure in the secondary battery 10 is increased due to the generation of gas. When the internal pressure of the case 11 reaches the open pressure of the pressure release valve 18, the valve body 20 a of the pressure release valve 18 is cleaved from the cleavage groove 20 b, and the gas in the case 11 is released outside the case 11.

  Further, the high-pressure gas generated in the short-circuit portion flows in the stacking direction along the nail F toward the inlet 51b of the exhaust passage 51 which is a large space, as indicated by an arrow Y in FIG. 51 flows into the inlet 51b. Then, as shown in FIG. 7, the high-pressure gas is separated into the two exhaust passages 51, rises in the exhaust passage 51, and is discharged from the exhaust port 51 a onto the tab side end surface 36 outside the shielding portion 61. Thereafter, the direction is changed toward the pressure release valve 18. Then, the gas flows along the conductive members 26, 28 and the lid body 14 from the outside of the shielding portion 61, reaches the pressure release valve 18, and is released from the cleaved pressure release valve 18 to the outside of the case 11. .

  In the present embodiment, the place where the nail F is inserted is the central portion of the end surface 44 of the electrode assembly 12 and the vicinity of the inlet 51b of the exhaust passage 51. However, the place where the nail F is inserted is the flow of the exhaust passage 51. Even outside the vicinity of the inlet 51b, the high-pressure gas flows into the exhaust passage 51 and is released from the case 11 through the pressure release valve 18.

  Further, part of the high-pressure gas that has not flowed into the exhaust passage 51 rises in the electrode assembly 12. The gas is released from the tab-side end surface 36 located in the covering region H, collides with the outer surface 61a of the shielding portion 61 of the shielding member 60, and changes its direction along the outer surface 61a. The gas whose direction has changed due to the collision with the shielding part 61 rises along the first rib 62 and the second rib 63, and passes through the gap between the tip surface of each rib 62, 63 and the inner surface 14 c of the lid body 14. To the pressure relief valve 18. Thereafter, the gas is discharged out of the case 11 from the cleaved pressure release valve 18.

According to the above embodiment, the following effects can be obtained.
(1) The exhaust port 51a of the exhaust passage 51 is opened toward a position outside the pressure release valve 18 on the inner surface 14c of the lid body 14. For this reason, the gas released from the exhaust port 51 a of the exhaust passage 51 then flows toward the pressure release valve 18. As a result, the gas discharge path from the short circuit part to the pressure release valve 18 can be made longer than when the gas generated in the short circuit part flows directly into the pressure release valve 18. As a result, it is possible to prevent a part of the electrode from dropping from the gas in the middle of the gas toward the pressure release valve 18 and a part of the electrode from scattering from the cleaved pressure release valve 18 to the outside of the case 11.

  (2) The exhaust passage 51 is provided using the thickness adjusting member 50 stacked outside the end face 44 of the electrode assembly 12. For this reason, most of the gas can flow outside the electrode assembly 12. For example, the positive electrode 21 and the negative electrode exposed to high-pressure gas as compared with the case where most of the gas rises in the electrode assembly 12. The number of 22 is reduced. As a result, it is possible to suppress a part of the positive electrode 21 and the negative electrode 22 from being scraped by the high-pressure gas, and it is possible to suppress a part of the electrode from being scattered as the gas is released to the outside of the case 11.

  (3) The secondary battery 10 includes two exhaust passages 51 and two exhaust ports 51a. For this reason, the gas can be dispersed in the two exhaust passages 51. Therefore, the momentum of the gas can be weakened as compared with, for example, a single exhaust passage.

  (4) The exhaust port 51a of the exhaust passage 51 is opened toward a position on the inner surface 14c of the lid body 14 that is outside the shielding portion 61 that covers the pressure release valve 18. For this reason, the exhaust port 51a is located further away from the pressure release valve 18. Therefore, the gas discharge path of the gas that flows around the shielding portion 61 can be made longer. As a result, it is possible to prevent a part of the electrode from dropping from the gas in the middle of the gas toward the pressure release valve 18 and a part of the electrode from scattering from the cleaved pressure release valve 18 to the outside of the case 11.

  (5) The exhaust passage 51 exists between each end surface 44 of the electrode assembly 12 and each long side wall 13d. During the nail penetration test, gas is first generated near the end face 44 where the nail F first penetrates. For this reason, the inflow port 51b of the exhaust passage 51 exists in the immediate vicinity of the place where the gas is first generated, and the generated gas can be quickly supplied to the exhaust passage 51.

  (6) The exhaust passage 51 is formed by laminating the passage forming portions 50 f of the thickness adjusting member 50. The thickness adjusting member 50 is a member for adjusting the length of the electrode assembly 12 and the thickness adjusting member 50 in the stacking direction within a predetermined range. Therefore, the thickness adjusting member 50 is a member that does not contribute to the performance of the secondary battery 10. Therefore, the exhaust passage 51 can be provided in the case 11 without changing the performance of the secondary battery 10 and without increasing the number of parts.

  (7) Since the exhaust passage 51 is formed by laminating the passage forming portions 50f of the thickness adjusting members 50, the exhaust passage 51 can be formed even if the number of the thickness adjusting members 50 is different.

  (8) The thickness adjusting member 50 is integrated with the electrode assembly 12 by the holding tape 45. Therefore, the exhaust passage 51 formed by the thickness adjusting member 50 can also be provided integrally with the electrode assembly 12, and the gas generated from the electrode assembly 12 can easily flow toward the exhaust passage 51.

  (9) The thickness adjusting members 50 are disposed on both sides of the electrode assembly 12 in the stacking direction, and the exhaust passages 51 are also present on both sides of the electrode assembly 12 in the stacking direction. For this reason, even if the nail F stabs from any of the lamination directions of the electrode assembly 12, it can suppress that a gas flows into the exhaust passage 51 and the positive electrode 21 and the negative electrode 22 are exposed to a high pressure gas.

  (10) The shielding part 61 of the shielding member 60 covers the pressure release valve 18 from the electrode assembly 12 side. For this reason, during the nail penetration test, the gas directed to the pressure release valve 18 is collided with the outer surface 61a of the shielding portion 61, the direction of gas flow is removed from the path directly flowing into the pressure release valve 18, and the gas release direction is directed to the pressure release valve 18. The gas discharge path can be lengthened. As a result, both of the exhaust passage 51 and the shielding portion 61 cause a part of the positive electrode 21 and the negative electrode 22 included in the gas to fall more from the gas, and the electrode that scatters out of the case 11 from the cleaved pressure release valve 18. Some amount can be reduced.

In addition, you may change the said embodiment as follows.
The thickness adjusting member 50 is not interposed between the end surface 44 of the electrode assembly 12 and the long side wall 13d, but is interposed in the middle of the stacking direction in the electrode assembly 12, and is in the middle of the stacking direction. The exhaust passage 51 may be provided by the passage forming portion 50 f of one or a plurality of thickness adjusting members 50.

  When configured in this way, the high-pressure gas generated in the vicinity of the short-circuit portion flows toward the exhaust passage 51 along the stacking direction, collects in the exhaust passage 51, and rises together. For this reason, the positive electrode 21 and the negative electrode 22 which are exposed to high-pressure gas decrease. As a result, the positive electrode 21 and the negative electrode 22 scraped by the generated high-pressure gas during the nail penetration test are reduced, and it is possible to suppress a part of them from being scattered outside the case 11.

  In the embodiment, the sheet member is embodied as the thickness adjusting member 50 that adjusts the dimension in the stacking direction of the electrode assembly 12, but the sheet member is an insulating sheet that insulates the electrode assembly 12 from the case body 13. It may be a short-circuit electrode interposed between the electrode assembly 12 and the long side wall 13d. In this case, the insulating sheet and the short-circuit electrode may be one sheet or plural sheets.

  ○ The inlet 51b of the exhaust passage 51 is opened at the center of the end surface 44 of the electrode assembly 12, but the place where the inlet 51b of the exhaust passage 51 is opened is stuck with the nail F set in the nail penetration test. You may change according to the place.

  The number of the thickness adjusting members 50 may be appropriately changed according to the dimensions of the end face 44 and the long side wall 13d, may be one, or may be more or less than the number in the embodiment. The flow passage cross-sectional area of the exhaust passage 51 is changed according to the number of stacked thickness adjusting members 50.

  The channel forming part 50f may be recessed in the thickness of the thickness adjusting member 50, the insulating sheet as the sheet member, or the short-circuiting electrode, that is, a groove shape recessed in the stacking direction. When the exhaust passage 51 is formed by the single thickness adjusting member 50, the insulating sheet, or the short-circuit electrode, the groove-shaped passage forming portion 50f itself becomes the exhaust passage. On the other hand, when the exhaust passage 51 is formed by a plurality of thickness adjusting members 50, insulating sheets, or short-circuit electrodes, the groove-shaped passage forming portion 50f overlaps in the stacking direction to form an exhaust passage.

In addition, it is good also considering the sheet | seat member provided with the groove-shaped channel | path formation part 50f, and the sheet | seat member provided with the channel | path formation part 50f penetrated in the thickness direction as the exhaust path 51. FIG.
If the exhaust port 51a of the exhaust passage 51 opens toward the position outside the pressure release valve 18 in the inner surface 14c of the lid body 14, the position of the exhaust port 51a may be changed as appropriate. For example, the position of the exhaust port 51a may be further away from the pressure release valve 18 than in the embodiment along the longitudinal direction of the lid body 14, or may be closer.

As long as the exhaust port 51a of the exhaust passage 51 opens toward the position outside the pressure release valve 18 in the inner surface 14c of the lid body 14, three or more exhaust passages 51 may be provided.
As long as the exhaust port 51a of the exhaust passage 51 opens toward the position outside the pressure release valve 18 in the inner surface 14c of the lid body 14, the number of the exhaust passage 51 may be one.

  If the exhaust port 51a of the exhaust passage 51 opens toward the position outside the pressure release valve 18 on the inner surface 14c of the lid body 14, the exhaust passage 51 is not linearly extended but curved. Or may be bent.

  In embodiment, although the shielding part 61 was provided in the shielding member 60 mounted in the tab side end surface 36, the method of providing the shielding part 61 is not restricted to this. For example, as shown in FIG. 8, the negative electrode conductive member 28 may be extended in the longitudinal direction, and the negative electrode conductive member 28 may be provided with a shielding portion 70 that covers the pressure release valve 18 from the electrode assembly 12 side. Alternatively, the positive electrode conductive member 26 may be extended in the longitudinal direction, and the positive electrode conductive member 26 may be provided with a shielding portion 70 that covers the pressure release valve 18 from the electrode assembly 12 side. The shielding portion 70 is interposed between the inner surface 14c of the lid body 14 and the tab side end surface 36 of the electrode assembly 12, and covers the pressure release valve 18 from the electrode assembly 12 side.

O The shielding member 60 and the shielding part 70 may not be present.
The number of positive electrodes 21 and negative electrodes 22 constituting the electrode assembly 12 may be changed as appropriate.

  The thickness adjusting member 50 is interposed only between one end surface 44 of the electrode assembly 12 and the long side wall 13d, and the exhaust passage 51 is only between the one end surface 44 of the electrode assembly 12 and the long side wall 13d. May be present.

The electrode assembly may be a wound type in which one belt-like positive electrode and one belt-like negative electrode are wound around a winding shaft in a state where they are insulated by a separator.
The positive electrode 21 may be a type having a positive electrode active material layer 21b on one side of the positive electrode metal foil 21a, and the negative electrode 22 is a type having a negative electrode active material layer 22b on one side of the negative electrode metal foil 22a. It may be.

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

Next, the technical idea that can be grasped from the above embodiment and other examples will be described below.
(1) A power storage device in which an upstream end in a gas flow direction in the exhaust passage is open at a central portion of the electrode.

(2) The power storage device, wherein the exhaust passage exists between an end face located at least one end in the stacking direction of the electrode assembly and a side wall of the case facing the end face.
(3) The power storage device, wherein the sheet member is a thickness adjusting member that adjusts a dimension of the electrode assembly in a stacking direction.

  DESCRIPTION OF SYMBOLS 10 ... Secondary battery as a power storage device, 11 ... Case, 12 ... Electrode assembly, 14 ... Lid as wall, 14c ... Inner surface, 18 ... Pressure release valve, 21 ... Positive electrode as electrode, 22 ... Electrode , A tab side end surface as an end surface, 50 a thickness adjusting member as a sheet member, 50 f a passage forming portion, 51 an exhaust passage, 61 and 70 a shielding portion.

Claims (5)

An electrode assembly configured in layers with electrodes of different polarities insulated by separators;
An electrolyte,
A case for accommodating the electrode assembly and the electrolyte;
At least one sheet member stacked on the electrode assembly along the electrode stacking direction;
A power storage device having a pressure release valve that is present in a wall portion provided in the case, is cleaved when the pressure in the case reaches an open pressure, and releases the pressure in the case to the outside of the case,
The sheet member includes a passage forming portion that penetrates or is recessed in the stacking direction and extends in a surface direction of the sheet member,
An exhaust passage comprising the passage forming portion of the at least one sheet member;
The power storage device according to claim 1, wherein a downstream end of the exhaust passage in the gas flow direction is open toward a position outside the pressure release valve among positions along the surface direction of the wall portion.   The power storage device according to claim 1, wherein there are a plurality of exhaust passages.   The interposition between the inner surface of the wall portion and the end surface of the electrode assembly facing the inner surface includes a shielding portion that covers the pressure release valve from the electrode assembly side. Power storage device.   4. The power storage device according to claim 3, wherein a downstream end of the exhaust passage in a gas flow direction opens toward a position outside the shielding portion among positions along the surface direction of the wall portion.   The power storage device according to any one of claims 1 to 4, wherein the power storage device is a secondary battery.

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