JP2020102413A - Power storage device - Google Patents

Abstract

To provide a power storage device capable of excellently switching a penetration hole with a valve even in the configuration that the penetration is formed at a position deviated from a center of a wall part.SOLUTION: A secondary battery comprises a valve 16 to which a penetration hole 14h is switchably attached to an inner face 14x of a lid 14. The lid 14 is formed in a rectangular shape, and the penetration hole 14h is arranged at a position deviated from a center C of a short direction of the lid 14. The valve 16 includes: a thin-plate like valve part 16a switching the penetration hole 14h; a fixed part 16b fixed to the inner face 14x of the lid 14; and a thin-plate like connection part 16c connecting the valve part 16a and the fixed part 16b. The fixed part 16b is positioned on the valve part 16a side from the center C of the short direction of the lid 14. One part of the connection part 16c is positioned at the side opposite to the valve part 16a from the center C of the short direction of the lid 14. No connection part 16c exists on a virtual line L connecting the valve part 16a and the fixed part 16b by setting the valve part 16a as one end L1 and setting the fixed part 16b as other end L2 in a minimal length.SELECTED DRAWING: Figure 2

Description

The present invention relates to a power storage device including a valve body that can open and close a through hole formed in a wall portion of a case.

A secondary battery such as a lithium-ion secondary battery is mounted on a vehicle such as an EV (Electric Vehicle) or a PHV (Plug in Hybrid Vehicle) as a power storage device for storing electric power used in electric components and a traveling motor. ing. For example, the secondary battery includes an electrode assembly in which an electrode having an active material layer is laminated on both surfaces or one surface of a current collector, an electrolytic solution, and a case containing the electrode assembly and the electrolytic solution. The case has a rectangular parallelepiped case body and a rectangular lid that closes an opening of the case body and has a through hole formed therein. The through hole of the lid is sealed by the sealing member. The case may be expanded and deformed by the gas generated inside the case when the secondary battery is used. At this time, the deformation amount of the lid is larger at the center than at the end portion in the lateral direction of the lid. Therefore, in order to ensure the sealing of the through-hole by the sealing member even if the lid is deformed when the secondary battery is used, the through-hole is placed at a position with a small deformation amount deviated from the center of the lid in the lateral direction. May be placed.

In the manufacturing process of such a secondary battery, the electrode assembly is housed inside the case, and the liquid injection step of injecting the electrolytic solution into the case through the through hole, and the through hole after the liquid injection step is a temporary sealing member. And a temporary sealing step of temporarily sealing. Further, the manufacturing process of the secondary battery includes an initial charging/discharging process of performing initial charging/discharging in order to activate and stabilize the power storage device. In the initial charging/discharging step, a treatment such as one-time charging or multiple-time charging/discharging and, if necessary, aging for storing for a predetermined period in a constant temperature state are performed. In the manufacturing process of the secondary battery, by removing the temporary sealing member from the through hole and releasing the temporary sealing, the gas inside the case generated in the initial charging/discharging step is released from the through hole to the outside of the case. A degassing step is provided. Further, the manufacturing process of the secondary battery includes a filling process of filling the inside of the case with helium from the through hole and a main sealing process of main sealing the through hole with the main sealing member. Furthermore, the manufacturing process of the secondary battery includes an airtightness inspection process for inspecting the airtightness of the case by detecting the leakage of helium from the inside of the case.

By the way, since helium is a light gas as is generally known, it easily leaks from the through hole to the outside of the case between the filling step and the main sealing step. Therefore, it is possible to suppress the leakage of helium by providing the valve element disclosed in Patent Document 1 on the inner surface of the lid. The valve body included in the secondary battery of Patent Document 1 has a rectangular shape and is arranged such that the central portion closes the through hole from the inside of the lid. Further, the valve body is attached to the lid by joining the inner surface of the lid except for a part of the four sides. When an external force is applied to the valve body from the outside of the case through the through hole, the central portion of the valve body is pushed down toward the inside of the case, and a gap is formed between the valve body and the inner surface of the lid. The gap and the through hole allow the inside and outside of the case to communicate with each other.

JP, 2003-142060, A

However, when the valve element disclosed in Patent Document 1 is arranged on the inner surface of the lid, the workability of the liquid injection step and the filling step may be deteriorated due to the presence of the valve element. Therefore, for example, it is conceivable that only one of the four sides of the valve body is joined to the inner surface of the lid to improve the opening/closing performance of the valve body, but in this case, the amount by which the valve body is pushed down becomes large. Therefore, it is necessary to secure a space between the inner surface of the lid and the electrode assembly so that the depressed valve body does not interfere with the electrode assembly housed in the case. This space is a dead space that does not contribute to the battery capacity. In addition, the valve body must be placed so as to fit inside the lid. For example, when the through hole is placed off the center of the lid in the lateral direction, the shape and placement of the valve body are limited. There is.

The present invention has been made to solve the above problems, and an object thereof is to open and close the through hole by the valve body even if the through hole is formed at a position displaced from the center of the wall portion. An object of the present invention is to provide a power storage device that can improve the above.

An electricity storage device for solving the above-mentioned problems includes an electrode assembly, a case in which the electrode assembly is housed, a through hole is formed in a wall portion, helium is filled inside, and an inner surface of the wall portion. On the other hand, a valve body having the through hole attached so that it can be opened and closed, the wall portion in which the through hole is formed has a rectangular shape, and the through hole has a center in the lateral direction of the wall portion. The valve element is arranged at a position displaced from the thin plate-shaped valve portion that opens and closes the through hole, the fixing portion fixed to the inner surface of the wall portion, and the valve portion and the fixing portion are connected to each other. A thin plate-shaped connecting portion, the fixing portion is located closer to the valve portion than a center in the lateral direction of the wall portion, and the connecting portion is at least partly in the lateral direction of the wall portion. Is located on the side opposite to the valve portion with respect to the center of the valve portion, and does not exist on an imaginary line connecting the valve portion and the fixed portion at the shortest distance with the valve portion as one end and the fixed portion as the other end. That is the summary.

According to this, by arranging the fixing portion on the valve portion side with respect to the center in the lateral direction of the wall portion, the wall portion is connected to the side opposite to the valve portion with respect to the center in the lateral direction of the wall portion. The part in which the part is located is secured, and the connection part can be arranged in this secured part. Further, the connecting portion bypasses the gap between the valve portion and the fixed portion to connect the valve portion and the fixed portion. Therefore, as compared with the case where the connecting portion exists along the imaginary line, that is, the connecting portion connects the valve portion and the fixed portion at the shortest distance, the length of the connecting portion from the valve portion to the fixed portion is It becomes longer, and the force required to push down the valve body can be reduced. As a result, even if the through hole is formed at a position deviated from the center of the wall portion, the opening/closing property of the through hole by the valve body can be improved.

Further, in the above electricity storage device, the valve portion and the fixing portion are arranged at intervals in the longitudinal direction of the wall portion, and the connecting portion is a first straight line extending from the valve portion in the longitudinal direction of the wall portion. Section, a second straight section extending in the lateral direction of the wall section from an end of the first straight section opposite to the valve section, and a side of the second straight section opposite to the first straight section A third linear portion extending in the longitudinal direction of the wall portion from the end portion of the first linear portion and arranged in the lateral direction of the wall portion, and an opposite side of the second linear portion of the third linear portion. And a fourth straight portion extending in the lateral direction of the wall portion from the end portion to the fixed portion.

According to this, the valve body is formed of four linear portions and has a substantially rectangular shape in which a part is discontinuous due to the gap between the valve portion and the fixed portion. Therefore, the length of the connecting portion is longer than that in the case where the connecting portion has a U-shape composed of, for example, three linear portions, or when the connecting portion connects the valve portion and the fixed portion in a half-moon shape. Become. Therefore, the openability of the through hole can be improved.

Further, in the above electricity storage device, it is preferable that the valve body is a single leaf spring, and a rubber resin seal member is attached to a surface of the valve portion on the wall portion side.
According to this, in the state where the valve portion of the valve body is not pushed down, the valve portion of the valve body closes the through hole and the seal member comes into close contact with the inner surface of the lid. Therefore, the airtightness of the case can be improved. As a result, it is possible to further prevent helium from leaking out of the case from the through hole.

Further, in the power storage device, it is preferable that a portion of the valve portion that overlaps the through hole is a convex portion that faces the outside of the case.
According to this, in the state where the valve portion of the valve body is not pushed down, the valve portion of the valve body closes the through hole and the convex portion enters the inside of the through hole. Therefore, the airtightness of the case can be improved. As a result, it is possible to further prevent helium from leaking out of the case from the through hole.

Further, in the above electricity storage device, the valve body is made of an ultraviolet curable resin, and a portion surrounding the through hole in the valve portion is provided with a cured portion that is cured in a state of being in close contact with an inner surface of the wall portion. preferable.

According to this, by making the valve body made of resin, it is possible to improve the opening/closing property of the through hole by the valve body due to the spring property, and it is possible to suppress wear of the valve body when the through hole is repeatedly opened and closed. The hardened portion is formed by irradiating the valve portion with ultraviolet rays after filling the inside of the case with helium through the through hole. Since the hardened portion is hardened in a state of being in close contact with the inner surface of the wall portion, the airtightness of the case can be improved. As a result, it is possible to further prevent helium from leaking out of the case from the through hole.

According to the present invention, even if the through hole is formed at a position deviated from the center of the wall portion, the opening/closing property of the through hole by the valve body can be improved.

The disassembled perspective view of a secondary battery. The bottom view of a lid. (A), (b) is the 3-3 sectional view taken on the line in FIG. The bottom view which shows another example of a valve body. The bottom view which shows another example of a valve body. The bottom view which shows another example of a valve body. The bottom view which shows another example of a valve body. Sectional drawing which shows another example of a valve body. Sectional drawing which shows another example of a valve body. Sectional drawing which shows another example of a valve body.

Hereinafter, an embodiment in which the power storage device is embodied as a secondary battery will be described with reference to FIGS. 1 to 3.
As shown in FIG. 1, a secondary battery 10 as a power storage device includes a rectangular parallelepiped case 11, an electrode assembly 12 housed in the case 11, and an electrolyte solution (not shown) housed in the case 11. The case 11 has a case body 13 in the shape of a square cylinder with a bottom, and a plate-like lid 14 that closes the opening 13 a of the case body 13. The case body 13 and the lid 14 form a wall portion of the case 11. The secondary battery 10 of the present embodiment is a prismatic battery whose appearance is prismatic. Further, the secondary battery 10 of the present embodiment is a lithium ion secondary battery.

Although not shown, the electrode assembly 12 includes a plurality of positive electrodes, a plurality of negative electrodes, and a plurality of separators. The electrode assembly 12 has a layered structure in which a separator is interposed between a positive electrode and a negative electrode and they are laminated in a state of being insulated from each other. Each of the positive electrode and the negative electrode has a rectangular sheet-shaped current collector, active material layers present on both surfaces of the current collector, and a tab 15 protruding from a part of one side of the current collector. The tab 15 does not have an active material layer and is composed of a current collector itself. The electrode assembly 12 has a tab group 12a in which a plurality of tabs 15 are laminated with the same polarities.

The lid 14 has a rectangular shape. Of the pair of long side edges, one long side edge is the first long side edge 14a, and the other long side edge is the second long side edge 14b. Also, of the pair of short side edges, one short side edge is the first short side edge 14c, and the other short side edge is the second short side edge 14d. Further, in the lid 14, a surface facing the inside of the case 11 is an inner surface 14x, and a surface facing the outside of the case 11 and a surface opposite to the inner surface 14x is an outer surface 14y.

The lid 14 has a round hole-shaped through hole 14h that penetrates the lid 14 in the plate thickness direction. The through hole 14h is located near the center in the longitudinal direction of the lid 14, and is located on the one end side closer to the first long side edge 14a than the center C in the lateral direction of the lid 14. That is, the through hole 14h is arranged at a position displaced from the center C in the lateral direction of the lid 14. Further, the lid 14 is provided with a thin plate-shaped valve body 16 arranged so as to open and close the through hole 14h with respect to the inner surface 14x of the lid 14. The valve element 16 of the present embodiment is a single leaf spring made of metal.

As shown in FIG. 2, the valve body 16 of the present embodiment is composed of rectangular first to fourth portions 21 to 24. The first portion 21 is located closer to the first long side edge portion 14a than the center C of the lid 14 in the lateral direction. The length of the first portion 21 extends in the longitudinal direction of the lid 14, and the short side of the first portion 21 extends in the short side direction of the lid 14. The second portion 22 is the second from the portion of the pair of long edge portions of the first portion 21 near the second short side edge portion 14d of the long edge portion closer to the second long side edge portion 14b of the lid 14. It extends in the lateral direction of the lid 14 toward the long side edge portion 14b. The length of the second portion 22 extends in the lateral direction of the lid 14, and the width of the second portion 22 extends in the longitudinal direction of the lid 14. Of the pair of long edge portions of the second portion 22, the third portion 23 is first from the portion of the long edge portion closer to the first short side edge portion 14c of the lid 14 near the second long side edge portion 14b. It extends in the longitudinal direction of the lid 14 toward the short side edge portion 14c. The length of the third portion 23 extends in the longitudinal direction of the lid 14, and the width of the third portion 23 extends in the width direction of the lid 14. The third portion 23 is located closer to the second long-side edge portion 14b than the center C of the lid 14 in the lateral direction. In the longitudinal direction of the lid 14, the dimension of the third portion 23 is longer than the dimension of the first portion 21. Of the pair of long edge portions of the third portion 23, the fourth portion 24 is the first from the portion of the long edge portion closer to the first long side edge portion 14a of the lid 14 near the first short side edge portion 14c. It extends in the lateral direction of the lid 14 toward the long side edge portion 14a. The length of the fourth portion 24 extends in the longitudinal direction of the lid 14, and the width of the fourth portion 24 extends in the width direction of the lid 14. The length of the fourth portion 24 extends so as to straddle the center C of the lid 14 in the lateral direction. A part of the fourth portion 24 is located closer to the first long side edge portion 14a than the center C of the lid 14 in the lateral direction.

The valve body 16 is arranged so that a part of the first portion 21 closes the entire through hole 14h of the lid 14. Therefore, a part of the first portion 21 is the valve portion 16a that closes the entire through hole 14h of the lid 14. Of the inner peripheral surface forming the through hole 14h, a position separated by a predetermined distance from the inner surface 141 closest to the second short side edge portion 14d in the longitudinal direction of the lid 14 toward the second short side edge portion 14d. The closed edge 161 is used. An imaginary straight line that passes through the closed edge portion 161 and extends along the lateral direction of the lid 14 is referred to as a first boundary portion B1. The valve portion 16a is a portion of the first portion 21 that is located closer to the first short-side edge portion 14c in the longitudinal direction of the lid 14 than the first boundary portion B1. The valve portion 16a is larger than the opening area of the through hole 14h and can close the entire through hole 14h. Further, as described above, the closed edge portion 161 of the valve portion 16a is located outside the inner surface 141 of the through hole 14h by a predetermined distance. Therefore, the through hole 14h is completely closed by the valve portion 16a.

The valve body 16 has a joint portion 25 as a fixing portion in which a part of the fourth portion 24 is joined to the inner surface 14x of the lid 14 by indirect spot welding. The valve body 16 is fixed to the lid 14 by the joint portion 25. Therefore, a part of the fourth portion 24 is the fixing portion 16b fixed to the lid 14. Of the peripheral portion of the joint portion 25, a virtual straight line passing through the edge portion 25a closest to the second long side edge portion 14b in the lateral direction of the lid 14 and extending along the longitudinal direction of the lid 14 is second. The boundary is B2. The fixing portion 16b is a portion of the fourth portion 24 that is located closer to the first long-side edge portion 14a in the lateral direction of the lid 14 than the second boundary portion B2. The fixed portion 16b is located on the valve portion 16a side (the first long side edge portion 14a side) with respect to the center C in the lateral direction of the lid 14. The valve portion 16a and the fixed portion 16b are arranged at intervals in the longitudinal direction of the lid 14. The valve element 16 has a substantially rectangular shape, a part of which is discontinuous due to a gap S between the valve portion 16a and the fixed portion 16b.

A straight line that virtually connects the valve portion 16a and the fixed portion 16b at the shortest distance is defined as an imaginary line L. The imaginary line L extends along the longitudinal direction of the lid 14. One end L1 of the imaginary line L is located at one of the pair of short edge portions of the first portion 21 which is closer to the first short side edge portion 14c in the longitudinal direction of the lid 14, and the other of the imaginary line L. The end L2 is located at the short edge of the pair of long edges of the fourth portion 24 that constitutes the fixing portion 16b, which is closer to the second short side edge 14d in the longitudinal direction of the lid 14.

The valve body 16 includes a connecting portion 16c that connects the valve portion 16a and the fixed portion 16b. The valve element 16 of the present embodiment is composed of first to fourth straight portions. The first straight portion is a portion extending from the valve portion 16a in the longitudinal direction of the lid 14, and is located closer to the second short side edge portion 14d in the longitudinal direction of the lid 14 than the first boundary portion B1 in the first portion 21. Corresponds to the part. The second linear portion is a portion that extends in the lateral direction of the lid 14 from the end of the first portion 21 on the opposite side to the valve portion 16 a, and corresponds to the entire second portion 22. The third linear portion is a portion that extends in the longitudinal direction of the lid 14 from the end of the second portion 22 opposite to the first portion 21, and that is aligned in the lateral direction of the first portion 21 and the lid 14, It corresponds to the whole of the three parts 23. The fourth straight portion is a portion extending in the lateral direction of the lid 14 from the end of the third portion 23 opposite to the second portion 22 toward the fixing portion 16b, and the second boundary portion of the fourth portion 24. It corresponds to the portion located on the second long side edge 14b side in the lateral direction of the lid 14 with respect to B2. A part of the connecting portion 16c is located on the side opposite to the valve portion 16a (on the side of the second long side edge portion 14b) with respect to the center C of the lid 14 in the lateral direction. Further, the connecting portion 16c does not exist on the virtual line L. That is, the connecting portion 16c bypasses the gap S between the valve portion 16a and the fixed portion 16b in the longitudinal direction of the lid 14 to connect the valve portion 16a and the fixed portion 16b.

As shown in FIG. 3A, when the external force F is not applied to the valve body 16, the valve portion 16a and the connecting portion 16c of the valve body 16 are along the inner surface 14x of the lid 14 and the through hole 14h. Is closed by a part of the valve portion 16a. Therefore, communication between the inside and outside of the case 11 via the through hole 14h is blocked. As shown in FIG. 3B, when an external force F is applied to the valve body 16 from the outside of the case 11 via the through hole 14h, the valve portion 16a of the valve body 16 is pushed down toward the inside of the case 11, The valve portion 16a and the connecting portion 16c of the valve body 16 are separated from the inner surface 14x of the lid 14. Therefore, a gap is formed between the valve portion 16a and the inner surface 14x of the lid 14, and the through hole 14h is opened. Therefore, the inside and outside of the case 11 communicate with each other through the gap and the through hole 14h. The valve portion 16a does not interfere with the electrode assembly 12 in the depressed state. Then, when the external force F is not applied to the valve body 16, the valve portion 16a returns from the depressed state to the state along the inner surface 14x of the lid 14, and the through hole 14h is closed by a part of the valve portion 16a.

As shown in FIG. 1, the secondary battery 10 includes a blind rivet 17 as a sealing member for sealing the through hole 14h. Note that FIG. 1 illustrates a state before the through hole 14h is sealed by the blind rivet 17.

The secondary battery 10 includes a positive electrode and a negative electrode terminal structure 18 for extracting electricity from the electrode assembly 12. Each terminal structure 18 has a plate-shaped conductive member 18a joined to the tab group 12a and a rod-shaped electrode terminal 18b protruding from the conductive member 18a. Each electrode terminal 18b penetrates the lid 14 and projects to the outside of the case 11 to connect the inside and outside of the case 11. The positive electrode terminal 18b penetrates a portion of the lid 14 near the second short side edge 14d in the longitudinal direction, and the negative electrode terminal 18b passes through a portion of the lid 14 near the first short side edge 14c in the longitudinal direction. Penetrate through. A bus bar as an external device (not shown) for electrically connecting the secondary batteries 10 to each other can be fixed to each electrode terminal 18b. Each terminal structure 18 electrically connects the electrode assembly 12 and the bus bar. The secondary battery 10 includes an insulating ring 19 for insulating the lid 14 and the electrode terminals 18b of the terminal structures 18 from each other.

The secondary battery 10 includes a pressure release valve 20 on the lid 14. The pressure release valve 20 is located between the positive electrode terminal 18b and the through hole 14h in the longitudinal direction of the lid 14 and does not overlap the valve body 16 when viewed from the outer surface 14y of the lid 14. The pressure release valve 20 is provided at the bottom of a recessed portion that is recessed from the outer surface 14y of the lid 14. The pressure release valve 20 is opened when the pressure in the case 11 reaches an opening pressure that is a predetermined pressure so that the pressure in the case 11 does not rise too much when gas is generated in the case 11. As a result, the inside and outside of the case 11 are in communication with each other, so that the pressure inside the case 11 is released to the outside of the case 11.

Next, a method of manufacturing the secondary battery 10 will be described.
The method of manufacturing the secondary battery 10 includes a housing step of housing the electrode assembly 12 in the case 11. In the housing step, the electrode assembly 12 is housed in the case body 13 through the opening 13a. Next, the opening 13a of the case body 13 is closed by the lid 14 having the valve body 16 attached to the inner surface 14x, and the case body 13 and the lid 14 are joined. The method for manufacturing the secondary battery 10 includes a liquid injection step of injecting an electrolytic solution into the case 11 from the through hole 14h with respect to the case 11 in which the electrode assembly 12 is housed. In the liquid injection step, for example, the nozzle of the liquid injection device (not shown) pushes down the valve portion 16a of the valve body 16 from the outside of the case 11 to open the through hole 14h and inject the electrolytic solution into the case 11. After the liquid injection step, the through hole 14h is closed by the valve portion 16a of the valve body 16.

The manufacturing method of the secondary battery 10 includes a temporary sealing step of temporarily sealing the through hole 14h with a temporary sealing member (not shown), and an initial charge/discharge in which the case 11 is held with a holding jig (not shown) to perform initial charge/discharge. And a process. The initial charging/discharging process of the present embodiment includes a conditioning process and an aging process. In the conditioning process, initial charging is performed. Depending on the specifications of the secondary battery 10, charging and discharging may be repeated a plurality of times. After the conditioning step, in the aging step, the secondary battery 10 is allowed to stand for a predetermined time while being heated to a predetermined aging temperature in a thermostat (not shown). The initial charge/discharge step is performed in a state where the through hole 14h is temporarily sealed by the temporary sealing member. After the initial charge/discharge step, the restraint of the case 11 by the restraint jig is released.

The method for manufacturing the secondary battery 10 is such that the temporary sealing of the through hole 14h is released by removing the temporary sealing member from the through hole 14h, and the gas generated inside the case 11 in the aging step is discharged from the through hole 14h to the case. A degassing step of releasing the gas to the outside of 11 is provided. In the degassing step, the through hole 14h is opened by pushing down the valve portion 16a of the valve body 16 from the outside of the case 11 by a pressing member (not shown), and the gas generated inside the case 11 is released from the through hole 14h to the outside of the case 11. To release. After the degassing step, the through hole 14h is closed by the valve portion 16a of the valve body 16.

The manufacturing method of the secondary battery 10 includes a filling step of filling the inside of the case 11 with helium from the through hole 14h. In the filling step, for example, the nozzle of the filling device (not shown) pushes down the valve portion 16a of the valve body 16 from the outside of the case 11 to open the through hole 14h and fill the inside of the case 11 with helium through the through hole 14h. After the filling step, the through hole 14h is closed by the valve portion 16a of the valve body 16. Therefore, the helium filled in the case 11 is suppressed from leaking out of the case 11 from the through hole 14h. In the method for manufacturing the secondary battery 10, the through-hole 14h is main-sealed by performing a main-sealing step of main-sealing the through-hole 14h with the blind rivet 17 and detecting a leak of helium from the inside of the case 11. And an airtightness inspection step of inspecting the airtightness of the case 11.

The operation and effect of this embodiment will be described.
(1) The valve body 16 includes a valve portion 16a for opening and closing the through hole 14h of the lid 14, a fixed portion 16b fixed to the inner surface 14x of the lid 14, and a connecting portion 16c for connecting the valve portion 16a and the fixed portion 16b. Have and. The fixed portion 16b is located closer to the valve portion 16a than the center C of the lid 14 in the lateral direction. Therefore, on the inner surface 14x of the lid 14, a portion for locating the connecting portion 16c is secured on the side opposite to the valve portion 16a with respect to the center C in the lateral direction of the lid 14, and the secured portion is secured. The connection portion 16c can be arranged in the. Further, the connecting portion 16c does not exist on the imaginary line L that connects the valve portion 16a and the fixed portion 16b. In other words, the connecting portion 16c bypasses the gap between the valve portion 16a and the fixed portion 16b to connect the valve portion 16a and the fixed portion 16b. Therefore, as compared with the case where the connecting portion 16c exists along the imaginary line L, that is, the case where the connecting portion 16c connects the valve portion 16a and the fixed portion 16b at the shortest distance, from the valve portion 16a to the fixed portion 16b. The connecting portion 16c has a longer length, and the force required to push down the valve body 16 can be reduced. As a result, even if the through hole 14h is formed at a position displaced from the center C of the lid 14 in the lateral direction, the openability of the through hole 14h by the valve body 16 can be improved.

(2) The valve body 16 is composed of four linear portions and has a substantially rectangular shape in which a part is discontinuous due to the gap S between the valve portion 16a and the fixed portion 16b. Therefore, for example, when the connecting portion 16c is U-shaped composed of three straight portions (see FIG. 4) or when the connecting portion 16c connects the valve portion 16a and the fixed portion 16b in a half-moon shape (see FIG. 6). The length of the connecting portion 16c is longer than that of the reference portion 16c. Therefore, the openability of the through hole 14h can be improved.

The present embodiment can be modified and implemented as follows. The present embodiment and the modified examples can be implemented in combination with each other within a technically consistent range.
The through hole 14h may be formed in the case body 13.

An insulating member for insulating the electrode assembly 12 and the lid 14 may be interposed between the electrode assembly 12 and the inner surface 14x of the lid 14.
The thickness of the valve body 16 may be different for the valve portion 16a, the fixed portion 16b, and the connecting portion 16c. However, the valve portion 16a and the connecting portion 16c are thin plates that can open and close the through hole 14h by the valve portion 16a.

The shape of the valve body 16 is not limited to the shape of the above-mentioned embodiment, and may satisfy the following configuration. The valve body 16 has a valve portion 16a for opening and closing the through hole 14h, a fixing portion 16b fixed to the inner surface 14x of the lid 14, and a connecting portion 16c for connecting the valve portion 16a and the fixing portion 16b. The fixed portion 16b is located closer to the valve portion 16a than the center C of the lid 14 in the lateral direction. At least a part of the connecting portion 16c is located on the side opposite to the valve portion 16a with respect to the center C in the lateral direction of the lid 14, and on the virtual line L connecting the valve portion 16a and the fixed portion 16b at the shortest distance. Does not exist in.

The shape of the valve body 16 may be the shape shown in FIGS. 4 to 7, for example.
The valve body 16 shown in FIG. 4 is composed of rectangular first to third portions 31 to 33. The length of the first portion 31 extends in the lateral direction of the lid 14, and the width of the first portion 31 extends in the longitudinal direction of the lid 14. The length of the first portion 31 extends so as to straddle the center C of the lid 14 in the lateral direction. Part of the first portion 31 is located closer to the first long-side edge portion 14a than the center C of the lid 14 in the lateral direction. The second portion 32 is the second from the portion of the pair of long edge portions of the first portion 31 closer to the second short side edge portion 14d of the lid 14 and closer to the second long side edge portion 14b. It extends in the longitudinal direction of the lid 14 toward the short side edge portion 14d. The length of the second portion 32 extends in the longitudinal direction of the lid 14, and the width of the second portion 32 extends in the width direction of the lid 14. The second portion 32 is located closer to the second long-side edge portion 14b than the center C of the lid 14 in the lateral direction. Of the pair of long edge portions of the second portion 32, the third portion 33 is the first from the portion of the long edge portion closer to the first long side edge portion 14a of the lid 14 near the second short side edge portion 14d. It extends in the lateral direction of the lid 14 toward the long side edge portion 14a. The length of the third portion 33 extends in the lateral direction of the lid 14, and the width of the third portion 33 extends in the longitudinal direction of the lid 14. The length of the third portion 33 extends so as to straddle the center C of the lid 14 in the lateral direction. A part of the third portion 33 is located closer to the first long side edge portion 14a than the center C of the lid 14 in the lateral direction.

The valve body 16 is arranged such that a part of the first portion 31 closes the entire through hole 14h of the lid 14. Therefore, a part of the first portion 31 is the valve portion 16a that closes the entire through hole 14h of the lid 14. A position separated by a predetermined distance from the inner surface 141 closest to the second long-side edge portion 14b in the lateral direction of the lid 14 to the second long-side edge portion 14b among the inner peripheral surface forming the through hole 14h. Is the closed edge 161. An imaginary straight line that passes through the closed edge portion 161 and extends along the lateral direction of the lid 14 is referred to as a first boundary portion B1. The valve portion 16a is a portion located in the first portion 31 on the first long side edge portion 14a side in the lateral direction of the lid 14 with respect to the first boundary portion B1. The valve portion 16a is larger than the opening area of the through hole 14h and can close the entire through hole 14h. Further, as described above, the closed edge portion 161 of the valve portion 16a is located outside the inner surface 141 of the through hole 14h by a predetermined distance. Therefore, the through hole 14h is completely closed by the valve portion 16a.

The valve body 16 has a joint portion 25 as a fixing portion in which a part of the third portion 33 is joined to the inner surface 14x of the lid 14 by indirect spot welding. The valve body 16 is fixed to the lid 14 by the joint portion 25. Therefore, a part of the third portion 33 is the fixing portion 16b fixed to the lid 14. Of the peripheral portion of the joint portion 25, a virtual straight line passing through the edge portion 25a closest to the second long side edge portion 14b in the lateral direction of the lid 14 and extending along the longitudinal direction of the lid 14 is second. The boundary is B2. The fixing portion 16b is a portion located closer to the first long side edge portion 14a in the lateral direction of the lid 14 than the second boundary portion B2 in the third portion 33. The fixed portion 16b is located on the valve portion 16a side (the first long side edge portion 14a side) with respect to the center C in the lateral direction of the lid 14. The valve portion 16a and the fixed portion 16b are arranged at intervals in the longitudinal direction of the lid 14. The valve element 16 has a U-shape that opens toward the first long side edge portion 14 a of the lid 14.

A straight line that virtually connects the valve portion 16a and the fixed portion 16b at the shortest distance is defined as an imaginary line L. The imaginary line L extends along the longitudinal direction of the lid 14. One end L1 of the imaginary line L is located at one of the pair of long edge portions of the first portion 31 that is closer to the second short side edge portion 14d in the longitudinal direction of the lid 14, and the other of the imaginary line L The end L2 is located at a short edge portion of the pair of long edge portions of the third portion 33, which is closer to the first short side edge portion 14c in the longitudinal direction of the lid 14.

The valve body 16 includes a connecting portion 16c that connects the valve portion 16a and the fixed portion 16b. The connecting portion 16c of the present embodiment is a portion located on the second long side edge portion 14b side in the lateral direction of the lid 14 with respect to the first boundary portion B1 in the first portion 31, and the entire second portion 32, The third portion 33 includes a portion located closer to the second long-side edge portion 14b in the lateral direction of the lid 14 than the second boundary portion B2. A part of the connecting portion 16c is located on the side opposite to the valve portion 16a (on the side of the second long side edge portion 14b) with respect to the center C of the lid 14 in the lateral direction. Further, the connecting portion 16c does not exist on the virtual line L. That is, the connecting portion 16c bypasses the gap S between the valve portion 16a and the fixed portion 16b in the longitudinal direction of the lid 14 to connect the valve portion 16a and the fixed portion 16b.

The valve body 16 shown in FIG. 5 is composed of rectangular first to fifth portions 41 to 45. The first portion 41 is located between the first long side edge portion 14a and the through hole 14h in the lateral direction of the lid 14. Therefore, the first portion 41 is located closer to the first long side edge portion 14a than the center C of the lid 14 in the lateral direction. The length of the first portion 41 extends in the longitudinal direction of the lid 14, and the width of the first portion 41 extends in the width direction of the lid 14. The second portion 42 is the second from the portion of the pair of long edge portions of the first portion 41 near the second short side edge portion 14d of the long edge portion closer to the second long side edge portion 14b of the lid 14. It extends in the lateral direction of the lid 14 toward the long side edge portion 14b. The length of the second portion 42 extends in the lateral direction of the lid 14, and the width of the second portion 42 extends in the longitudinal direction of the lid 14. Of the pair of long edge portions of the second portion 42, the third portion 43 is the first from the portion of the long edge portion closer to the first short side edge portion 14c of the lid 14 near the second long side edge portion 14b. It extends in the longitudinal direction of the lid 14 toward the short side edge portion 14c. The length of the third portion 43 extends in the longitudinal direction of the lid 14, and the width of the third portion 43 extends in the width direction of the lid 14. The third portion 43 is located closer to the second long side edge portion 14b than the center C in the lateral direction of the lid 14. Of the pair of long edge portions of the third portion 43, the fourth portion 44 is the first from the portion near the first short side edge portion 14c of the long edge portion closer to the first long side edge portion 14a of the lid 14. It extends in the lateral direction of the lid 14 toward the long side edge portion 14a. The length of the fourth portion 44 extends in the lateral direction of the lid 14, and the width of the fourth portion 44 extends in the longitudinal direction of the lid 14. The dimension of the fourth portion 44 is shorter than the dimension of the second portion 42 in the lateral direction of the lid 14. The fifth portion 45 is the second from the portion of the pair of long edges of the fourth portion 44 closer to the second short side edge 14 d of the lid 14 and closer to the first long side edge 14 a. It extends in the longitudinal direction of the lid 14 toward the short side edge portion 14d. The length of the fifth portion 45 extends in the longitudinal direction of the lid 14, and the short side of the fifth portion 45 extends in the short side direction of the lid 14. The fifth portion 45 is located between the first portion 41 and the third portion 43 in the lateral direction of the lid 14.

The valve body 16 is arranged such that a part of the fifth portion 45 closes the entire through hole 14h of the lid 14. Therefore, a part of the fifth portion 45 is the valve portion 16a that closes the entire through hole 14h of the lid 14. Of the inner peripheral surface forming the through hole 14h, a position separated by a predetermined distance from the inner surface 141 closest to the first short side edge portion 14c in the longitudinal direction of the lid 14 toward the first short side edge portion 14c. The closed edge 161 is used. An imaginary straight line that passes through the closed edge portion 161 and extends along the lateral direction of the lid 14 is referred to as a first boundary portion B1. The valve portion 16a is a portion located closer to the second short side edge portion 14d in the longitudinal direction of the lid 14 than the first boundary portion B1 in the fifth portion 45. The valve portion 16a is larger than the opening area of the through hole 14h and can close the entire through hole 14h. Further, as described above, the closed edge portion 161 of the valve portion 16a is located outside the inner surface 141 of the through hole 14h by a predetermined distance. Therefore, the through hole 14h is completely closed by the valve portion 16a.

The valve body 16 has a joint portion 25 as a fixing portion in which a part of the first portion 41 is joined to the inner surface 14x of the lid 14 by indirect spot welding. The valve body 16 is fixed to the lid 14 by the joint portion 25. Therefore, the first portion 41 is the fixing portion 16b fixed to the lid 14. The fixed portion 16b is located on the valve portion 16a side (the first long side edge portion 14a side) with respect to the center C in the lateral direction of the lid 14. The valve portion 16a and the fixed portion 16b are arranged at intervals in the lateral direction of the lid 14. The valve body 16 has a spiral shape.

A straight line that virtually connects the valve portion 16a and the fixed portion 16b at the shortest distance is defined as an imaginary line L. The virtual line L extends along the lateral direction of the lid 14. One end L1 of the imaginary line L is located at a long edge portion of the pair of long edge portions of the fifth portion 45 forming the valve portion 16a, which is closer to the first long side edge portion 14a in the lateral direction of the lid 14. The other end L2 of the imaginary line L is located at a short edge portion of the pair of long edge portions of the first portion 41, which is closer to the second long side edge portion 14b in the short side direction of the lid 14.

The valve body 16 includes a connecting portion 16c that connects the valve portion 16a and the fixed portion 16b. The connecting portion 16c of the present embodiment is a portion located closer to the first short side edge portion 14c in the longitudinal direction of the lid 14 than the first boundary portion B1 in the second to fourth portions 42 to 44 and the fifth portion 45. It is composed of and. A part of the connecting portion 16c is located on the side opposite to the valve portion 16a (on the side of the second long side edge portion 14b) with respect to the center C of the lid 14 in the lateral direction. Further, the connecting portion 16c does not exist on the virtual line L. That is, the connecting portion 16c connects the valve portion 16a and the fixed portion 16b so as to bypass the gap S between the valve portion 16a and the fixed portion 16b in the lateral direction of the lid 14.

The valve body 16 shown in FIG. 6 includes a first portion 51 that extends linearly and a second portion 52 that extends arcuately. The first portion 51 is located closer to the first long side edge portion 14a than the center C of the lid 14 in the lateral direction. The first portion 51 has a rectangular shape whose longitudinal direction extends in the longitudinal direction of the lid 14 and whose lateral direction extends in the lateral direction of the lid 14. The second portion 52 has an arc shape that is concave toward the second long-side edge portion 14b in the lateral direction of the lid 14. Of both end portions of the second portion 52, one end portion close to the first short side edge portion 14c in the longitudinal direction of the lid 14 is one of the pair of long edge portions of the first portion 51 in the lateral direction of the lid 14. The second long side edge portion 14b is connected to a portion of the long edge portion near the first short side edge portion 14c. The other end of the second portion 52 close to the second short side edge 14d in the longitudinal direction of the lid 14 is located closer to the first long side edge 14a than the center C of the lid 14 in the lateral direction.

The valve body 16 is arranged such that a part of the first portion 51 closes the entire through hole 14h of the lid 14. Therefore, a part of the first portion 51 is the valve portion 16a that closes the entire through hole 14h of the lid 14. Further, of the inner peripheral surface forming the through hole 14h, the inner surface 141 closest to the first short side edge 14c in the longitudinal direction of the lid 14 is separated from the first short side edge 14c by a predetermined distance. The position is the closed edge 161. An imaginary straight line that passes through the closed edge portion 161 and extends along the lateral direction of the lid 14 is referred to as a first boundary portion B1. The valve portion 16a is a portion located closer to the second short side edge portion 14d in the longitudinal direction of the lid 14 than the first boundary portion B1 in the first portion 51. The valve portion 16a is larger than the opening area of the through hole 14h and can close the entire through hole 14h. Further, as described above, the closed edge portion 161 of the valve portion 16a is located outside the inner surface 141 of the through hole 14h by a predetermined distance. Therefore, the through hole 14h is completely closed by the valve portion 16a.

The valve body 16 has a joint portion 25 as a fixing portion in which a part of the second portion 52 is joined to the inner surface 14x of the lid 14 by indirect spot welding. The valve body 16 is fixed to the lid 14 by the joint portion 25. Therefore, a part of the second portion 52 is the fixing portion 16b fixed to the lid 14. Of the peripheral portion of the joint portion 25, a virtual straight line passing through the edge portion 25a closest to the second long side edge portion 14b in the lateral direction of the lid 14 and extending along the longitudinal direction of the lid 14 is second. The boundary is B2. The fixing portion 16b is a portion located closer to the first long side edge portion 14a in the lateral direction of the lid 14 than the second boundary portion B2 in the second portion 52. The fixed portion 16b is located on the valve portion 16a side (the first long side edge portion 14a side) with respect to the center C in the lateral direction of the lid 14. The valve portion 16a and the fixed portion 16b are arranged at intervals in the longitudinal direction of the lid 14.

A straight line that virtually connects the valve portion 16a and the fixed portion 16b at the shortest distance is defined as an imaginary line L. The imaginary line L extends along the longitudinal direction of the lid 14. One end L1 of the virtual line L is located at a short edge portion of the pair of short edge portions of the first portion 51 closer to the second short side edge portion 14d in the longitudinal direction of the lid 14, and the other virtual line L The end L2 is located on the inner peripheral edge of the second portion 32.

The valve body 16 includes a connecting portion 16c that connects the valve portion 16a and the fixed portion 16b. The connecting portion 16c of the present embodiment is a portion located closer to the first short side edge portion 14c in the longitudinal direction of the lid 14 than the first boundary portion B1 in the first portion 51, and the second boundary portion in the second portion 52. And a portion located closer to the second long side edge 14b in the lateral direction of the lid 14 than B2. A part of the connecting portion 16c is located on the side opposite to the valve portion 16a (on the side of the second long side edge portion 14b) with respect to the center C of the lid 14 in the lateral direction. Further, the connecting portion 16c does not exist on the virtual line L. That is, the connecting portion 16c bypasses the gap S between the valve portion 16a and the fixed portion 16b in the longitudinal direction of the lid 14 to connect the valve portion 16a and the fixed portion 16b.

The valve element 16 shown in FIG. 7 has an elliptical shape in which one circumferential position is discontinuous. One end and the other end of the valve element 16 are located closer to the first long side edge 14a than the center C of the lid 14 in the lateral direction. The valve body 16 is arranged so that one end thereof closes the through hole 14h of the lid 14. Therefore, one end of the valve body 16 is a valve portion 16a that closes the through hole 14h of the lid 14. Of the inner peripheral surface forming the through hole 14h, a position separated by a predetermined distance from the inner surface 141 closest to the first short side edge portion 14c in the longitudinal direction of the lid 14 toward the first short side edge portion 14c. The closed edge 161 is used. An imaginary straight line that passes through the closed edge portion 161 and extends along the lateral direction of the lid 14 is referred to as a first boundary portion B1. One end portion of the valve body 16 that is the valve portion 16a is a portion of the valve body 16 from the first boundary portion B1 to one end edge 162 in the circumferential direction. The valve portion 16a is larger than the opening area of the through hole 14h and can close the entire through hole 14h. Further, as described above, the closed edge portion 161 of the valve portion 16a is located outside the inner surface 141 of the through hole 14h by a predetermined distance. Therefore, the through hole 14h is completely closed by the valve portion 16a.

The valve body 16 has a joint portion 25 as the fixing portion, the other end portion of which is joined to the inner surface 14x of the lid 14 by indirect spot welding. The valve body 16 is fixed to the lid 14 by the joint portion 25. Therefore, the other end of the valve body 16 is a fixed portion 16b fixed to the lid 14. Of the peripheral portion of the joint portion 25, a virtual straight line passing through the edge portion 25a closest to the second long side edge portion 14b in the lateral direction of the lid 14 and extending along the longitudinal direction of the lid 14 is second. The boundary is B2. The other end portion of the valve body 16 that constitutes the fixed portion 16b is a portion of the valve body 16 from the second boundary portion B2 to the other end edge 163 in the circumferential direction. The fixed portion 16b is located closer to the valve portion 16a than the center C of the lid 14 in the lateral direction. The valve portion 16a and the fixed portion 16b are arranged side by side in the circumferential direction of the valve body 16 with an interval.

A straight line that virtually connects the valve portion 16a and the fixed portion 16b at the shortest distance is defined as an imaginary line L. One end L1 of the virtual line L is located at one end edge 162 of the valve body 16, and the other end L2 of the virtual line L is located at the other end edge 163 of the valve body 16.

The valve body 16 includes a connecting portion 16c that connects the valve portion 16a and the fixed portion 16b. The connecting portion 16c of the present embodiment is configured by the portion from the first boundary portion B1 to the second boundary portion B2 in the valve body 16. A part of the connecting portion 16c is located on the side opposite to the valve portion 16a (on the side of the second long side edge portion 14b) with respect to the center C of the lid 14 in the lateral direction. Further, the connecting portion 16c does not exist on the virtual line L. That is, the connecting portion 16c bypasses the gap S between the valve portion 16a and the fixed portion 16b to connect the valve portion 16a and the fixed portion 16b.

○ Depending on the arrangement of the valve portion 16a and the fixing portion 16b on the first long side edge 14a side of the center C of the lid 14 in the lateral direction, the entire connecting portion 16c is located in the center C of the lid 14 in the lateral direction. On the other hand, it may be located on the opposite side of the valve portion 16a.

As shown in FIG. 8, a seal member 26 made of rubber resin may be attached to the surface of the valve portion 16a of the valve body 16 on the lid 14 side. The seal member 26 has a diameter larger than that of the through hole 14h. In this case, in the state where the valve portion 16a of the valve body 16 is not pushed down, the valve portion 16a closes the through hole 14h, and the seal member 26 comes into close contact with the inner surface 14x of the lid 14. Therefore, the airtightness of the case 11 can be improved. As a result, it is possible to further prevent helium from leaking out of the case 11 from the through hole 14h.

As shown in FIG. 9, the portion of the valve portion 16a of the valve body 16 that overlaps the through hole 14h may be a convex portion 16d facing the outside of the case 11. In this case, in a state where the valve portion 16a of the valve body 16 is not pushed down, the valve portion 16a of the valve body 16 closes the through hole 14h and the convex portion 16d enters the inside of the through hole 14h. Therefore, the airtightness of the case 11 can be improved. As a result, it is possible to further prevent helium from leaking out of the case 11 from the through hole 14h.

As shown in FIG. 10, the valve body 16 may be made of an ultraviolet curable resin. Further, the valve body 16 may be provided with a cured portion 16e cured by irradiation of ultraviolet rays within the thickness of the valve body 16. The hardened portion 16e is formed in about half of the valve body 16 on the lid 14 side in the thickness direction. The hardened portion 16e has a substantially cylindrical shape whose diameter decreases from one end surface on the lid 14 side toward the other end surface on the electrode assembly 12 side. The area of the one end surface of the hardened portion 16e is larger than the opening area of the through hole 14h. The hardened portion 16e is formed in a portion of the valve portion 16a exposed from the through hole 14h to the outside of the case 11 and a portion of the valve portion 16a surrounding the through hole 14h.

The hardened portion 16e is formed by irradiating the valve portion 16a with ultraviolet rays from the outer surface 14y side of the lid 14 after the filling step. The portion of the valve portion 16a exposed to the outside of the case 11 is cured by being directly irradiated with the ultraviolet rays that have passed through the through holes 14h, and the portion of the valve portion 16a exposed to the outside of the case 11 is cured. The portion of the valve portion 16a surrounding the through hole 14h is also hardened. At this time, the portion of the valve portion 16a surrounding the through hole 14h is hardened in a state of being in close contact with the inner surface 14x of the lid 14.

When the valve element 16 is made of resin, the opening and closing of the through hole 14h by the valve element 16 can be improved by the spring property, and the wear of the valve element 16 when the through hole 14h is repeatedly opened and closed can be suppressed. Further, the hardened portion 16e formed in the portion surrounding the through hole 14h in the valve portion 16a is hardened in a state of being in close contact with the inner surface 14x of the lid 14, so that the airtightness of the case 11 is improved. Therefore, it is possible to further prevent helium from leaking out of the case 11 through the through hole 14h.

The method of fixing the valve body 16 to the lid 14 is not limited to indirect spot welding, and may be changed as appropriate.
The electrode assembly 12 is not limited to the so-called laminated type electrode assembly described in the above embodiment, and a strip-shaped positive electrode, a strip-shaped separator, and a strip-shaped negative electrode are laminated and wound in this order. It may be a circular electrode assembly.

The main sealing member is not limited to the blind rivet 17 and may be appropriately changed as long as the through hole 14h can be main sealed.
The power storage device can also be applied to power storage devices other than secondary batteries, such as capacitors.

10... Secondary battery as power storage device, 11... Case, 12... Electrode assembly, 14... Lid as wall part, 14h... Through hole, 14x... Inner surface, 16... Valve body, 16a... Valve part, 16b... Fixed Part, 16c... connection part, 16d... convex part, 16e... hardening part, 21... first part as first linear part, 22... second part as second linear part, 23... third part as third linear part 3 parts, 24... 4th part as a 4th linear part, 26... Seal member, C... Center, L... Virtual line, L1... One end, L2... The other end.

Claims (5)

An electrode assembly,
A case in which the electrode assembly is housed, a through hole is formed in the wall portion, and helium is filled in the inside,
A valve body attached to the inner surface of the wall portion so that the through hole can be opened and closed;
Equipped with
The wall portion in which the through hole is formed is rectangular, the through hole is arranged at a position displaced from the center of the wall portion in the lateral direction,
The valve body has a thin plate-shaped valve portion that opens and closes the through hole, a fixed portion fixed to an inner surface of the wall portion, and a thin plate-shaped connection portion that connects the valve portion and the fixed portion. Then
The fixing portion is located closer to the valve portion than the center in the lateral direction of the wall portion,
At least a part of the connecting portion is located on the opposite side to the valve portion with respect to the center in the lateral direction of the wall portion, the valve portion is one end, and the fixing portion is the other end. A power storage device, wherein the power storage device does not exist on a virtual line that connects the fixed portion and the fixed portion at the shortest distance. The valve portion and the fixed portion are arranged at intervals in the longitudinal direction of the wall portion,
The connection is
A first straight portion extending from the valve portion in the longitudinal direction of the wall portion;
A second straight portion extending in the lateral direction of the wall portion from an end portion of the first straight portion opposite to the valve portion;
A third straight line portion extending from the end of the second straight line portion opposite to the first straight line portion in the longitudinal direction of the wall portion, and a third straight line portion arranged in the short side direction of the wall portion;
A fourth straight portion extending in the lateral direction of the wall portion from the end of the third straight portion opposite to the second straight portion toward the fixed portion;
The power storage device according to claim 1, comprising: The valve body is a leaf spring,
The power storage device according to claim 1 or 2, wherein a seal member made of rubber resin is attached to a surface of the valve portion on the wall portion side. The power storage device according to claim 1, wherein a portion of the valve portion that overlaps the through hole is a convex portion that faces the outside of the case. The valve body is made of an ultraviolet curable resin, and a curing portion cured in a state of being in close contact with an inner surface of the wall portion is provided in a portion of the valve portion surrounding the through hole. Power storage device.