Energy storage devices

Abstract

A power storage device, according to the present disclosure, is equipped with: a power storage element; a bottomed cylindrical case that accommodates the power storage element and that has an opening at one end thereof; and a sealing body that seals the opening. The case has, near the opening thereof, a first pressing part that presses the side surface of the sealing body and protrudes to the inside the case, and a second pressing part that presses the upper surface of the sealing body. Formed on the upper surface of the sealing body is a slit that extends further to the inside of the case in the radial direction thereof than the second pressing part and that opens the side surface of the sealing body.

Description

[Technical Field]

[0001] The present disclosure relates to an electricity storage device. [Background technology]

[0002] Conventionally, there has been known an electric storage device (e.g., an electrolytic capacitor) that includes an electric storage element, a cylindrical case with a bottom that houses the electric storage element, and a sealing body that seals the opening of the case. Some such electric storage devices have a groove, such as a cross groove, formed on the bottom of the case as an explosion-proof mechanism. The bottom of this groove is weaker than the surrounding area. Therefore, when the internal pressure of the case increases, the case tears starting from the groove, and gas inside the case escapes through the tear. This prevents the sealing part of the electric storage device from bursting.

[0003] To ensure reliable operation of the explosion-proof mechanism consisting of a groove, a safety margin is provided between the allowable internal case pressure and the activation pressure of the explosion-proof mechanism, and between the activation pressure of the explosion-proof mechanism and the sealing strength. However, as the sealing body deteriorates, the sealing strength of the energy storage device decreases, and the internal case pressure at which the sealing part ruptures decreases. Meanwhile, the internal case pressure at which the explosion-proof mechanism consisting of a groove activates remains unchanged. Therefore, depending on the deterioration state of the sealing body, there is the disadvantage that the sealing part may rupture before the explosion-proof mechanism activates.

[0004] On the other hand, the electricity storage device proposed in Patent Document 1 has a groove or slit formed on the side of the sealing body, extending from one of the upper and lower edges to the other. This groove or slit is normally closed, but opens when the internal pressure of the case rises abnormally, thereby functioning as an explosion-proof mechanism that allows gas inside the case to escape. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 6191015 Summary of the Invention

[0006] However, because the groove or slit in Patent Document 1 is formed from the upper edge to the lower edge of the sealing body, there is a risk that it may open even if the internal pressure of the case does not increase significantly if the sealing body deteriorates over time. In other words, due to its structure, the explosion-proof mechanism in Patent Document 1 may lose operational reliability over time. In light of this situation, one of the objects of the present disclosure is to provide an electricity storage device equipped with an explosion-proof mechanism that can maintain high operational reliability.

[0007] One aspect of the present disclosure relates to an electricity storage device, the electricity storage device including: an electricity storage element; a cylindrical case that houses the electricity storage element and has an opening at one end; and a sealing body that seals the opening, wherein the case has a sealing member that seals the opening near the opening. The device has a first pressing portion and a second pressing portion, and the first pressing portion is Pressing the side of the sealing body, it protrudes into the inside of the case. The second pressing portion is Press the top surface of the sealing body death, The sealing body The sealing body On the top surface of The slit has: The second pressing portion extends radially inward of the case and opens to the side surface of the sealing body. do.

[0008] According to the present disclosure, an electricity storage device having an explosion-proof mechanism capable of maintaining high operational reliability can be obtained. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a cross-sectional view passing through a slit, which schematically shows an example of an electricity storage device according to the present disclosure. [Figure 2] FIG. 2 is a plan view schematically showing the sealing member. [Figure 3] FIG. 3 is an enlarged cross-sectional view showing a main part of the electricity storage device when the internal pressure of the case increases. DETAILED DESCRIPTION OF THE INVENTION

[0010] An embodiment of the power storage device according to the present disclosure will be described below using examples. However, the present disclosure is not limited to the examples described below. In the following description, specific numerical values ​​and materials may be used as examples, but other numerical values ​​and materials may be used as long as the effects of the present disclosure are obtained.

[0011] (Electricity storage device) The power storage device according to the present disclosure includes a power storage element, a case, and a sealing body, which will be described below.

[0012] (storage element) The electricity storage element includes electrodes, an electrolyte, and the like. For example, when the electricity storage device is an electrolytic capacitor, the electricity storage element includes a wound body. The wound body is formed by winding a pair of electrodes with a separator interposed therebetween. Both of the pair of electrodes may be polarizable electrodes, or one may be an anode and the other a cathode. For example, when the electricity storage device is a secondary battery or a lithium ion capacitor, the electricity storage element includes an electrode group. The electrode group is formed by winding a positive electrode and a negative electrode with a separator interposed therebetween. The electricity storage element may further include an electrolyte or a liquid component.

[0013] (case) The case has a cylindrical shape with a bottom and an opening at one end, and houses the electricity storage element. The case may be made of a metal such as aluminum, iron, or nickel. The shape of the case is not particularly limited, and may be, for example, a cylindrical shape with a bottom.

[0014] (sealing body) The gasket seals the opening of the case. The gasket is made of an elastic material (e.g., a material containing an elastic resin). The shape of the gasket may correspond to the shape of the case. For example, if the case is cylindrical with a bottom, the gasket may be disk-shaped, and if the case is rectangular with a bottom, the gasket may be rectangular plate-shaped.

[0015] The elastic resin is preferably a rubber component, such as butyl rubber (IIR), nitrile rubber (NBR), ethylene propylene rubber, ethylene propylene diene rubber (EPDM), chloroprene rubber (CR), isoprene rubber (IR), or Hypalon. (trademark) Rubber, silicone rubber, fluororubber, etc. can be used alone or in blends. Of these, butyl rubber, ethylene propylene rubber, fluororubber, etc. are preferred. In addition to the elastic resin, the elastic material may contain optional components such as fillers, carbon black, processing aids, and crosslinking aids.

[0016] The case has a first pressing portion and a second pressing portion near the opening.

[0017] The first pressing portion presses against the side surface of the sealing body and protrudes toward the inside of the case. The inner diameter of the first pressing portion at its most protruding apex may be smaller than the outer diameter of the sealing body when no load is applied. The first pressing portion may be formed, for example, by groove cutting to reduce the diameter of a portion of the opening.

[0018] The second pressing portion is disposed closer to one end of the case than the first pressing portion, i.e., closer to the opening, and presses the edge of the sealing body toward the inside of the case. The second pressing portion may be formed, for example, by curling a portion of the outermost end of the opening.

[0019] A slit is formed on the top surface of the sealing body. The slit extends radially inward of the case beyond the second pressing portion. The slit opens to the side surface of the sealing body. Here, the slit is formed at the most protruding apex of the first pressing portion on the side surface of the sealing body. Location Above (opening side) Area The slit may be open only at the bottom surface of the sealing body (the inner surface of the case). The slit does not open at the bottom surface of the sealing body (the inner surface of the case). The slit may provide communication between the inside and outside of the case when the force acting on the first pressing portion from the sealing body falls below a predetermined value due to an increase in the internal pressure of the case.

[0020] When the internal pressure of the case increases, the sealing body expands in the axial direction of the case toward the outside of the case. When this axial expansion occurs, the area of ​​the sealing body that is in contact with the first pressing portion is displaced away from the first pressing portion, thereby weakening the force acting from the sealing body on the first pressing portion (elastic repulsive force against compression). When this acting force weakens below a predetermined value, gas inside the case passes between the sealing body and the first pressing portion. This gas escapes from inside the case to the outside through the slit, reducing the internal pressure of the power storage device and ensuring safety.

[0021] As such, the slits in the electricity storage device of the present disclosure do not open or close depending on the pressure inside the case. In this respect, they differ from the grooves or slits in the electricity storage device of Patent Document 1. Alternatively, the slits in the electricity storage device of the present disclosure are always open. Therefore, the problem of Patent Document 1, in which a slit that is normally closed opens when the sealing body deteriorates over time, does not occur. In other words, even if the sealing body deteriorates over time, the function of the slits of the present disclosure as an explosion-proof mechanism is not substantially impaired.

[0022] As described above, the present disclosure provides an electricity storage device equipped with an explosion-proof mechanism that can maintain high operational reliability. Furthermore, the present disclosure also provides an electricity storage device that can prevent unexpected explosion of the electricity storage device, such as scattering of the sealing member, by operating the explosion-proof mechanism.

[0023] A plurality of slits may be provided. When a plurality of slits are provided, the slits may be arranged at equal intervals in the circumferential direction of the case. This prevents asymmetric deformation of the sealing body and improves the operational reliability of the explosion-proof mechanism formed by the slits.

[0024] An example of an electricity storage device according to the present disclosure will be specifically described below with reference to the drawings. The components described above can be applied to the components of the example electricity storage device described below. The components of the example electricity storage device described below can be modified based on the above description. Furthermore, the matters described below may be applied to the above embodiment. Of the components of the example electricity storage device described below, components that are not essential to the electricity storage device according to the present disclosure may be omitted. Note that the diagrams shown below are schematic and do not accurately reflect the shapes and numbers of actual components.

[0025] As shown in FIG. 1, the electricity storage device 10 is configured as an electrolytic capacitor, and includes an electricity storage element 11, a case 20, and a sealing body 30.

[0026] The electricity storage element 11 includes a wound body. The wound body is formed by winding an anode foil and a cathode foil with a separator interposed therebetween. One end of lead tabs 12A and 12B are connected to the anode foil and the cathode foil, respectively. The wound body is formed by winding the lead tabs 12A and 12B. The other end of the lead tabs 12A and 12B are connected to lead wires 13A and 13B, respectively.

[0027] The case 20 has a cylindrical shape with a bottom and an opening 21 at one end, and houses the electricity storage element 11. The case 20 of this embodiment is made of aluminum, but is not limited to this. The case 20 of this embodiment has a cylindrical shape with a bottom, but is not limited to this. The axial length of the case 20 may be, for example, 60 to 80 mm before the first pressing portion 22 and the second pressing portion 23 described below are formed. The outer diameter of the case 20 may be, for example, 16 to 20 mm.

[0028] The sealing body 30 seals the opening 21 of the case 20. In this embodiment, the sealing body 30 is disk-shaped, but is not limited to this. The thickness of the sealing body 30 (the length in the axial direction of the case 20) may be, for example, 3 to 7 mm. The sealing body 30 may be made of an elastic body whose main component is rubber.

[0029] The opening 21 of the case 20 has a first pressing portion 22 and a second pressing portion 23.

[0030] First pressing portion 22 presses the side surface of sealing body 30 near opening 21 and protrudes inward of case 20. The inner diameter of first pressing portion 22 at apex 22a is smaller than the outer diameter of sealing body 30 when no load is applied. In this embodiment, first pressing portion 22 is formed by grooving to reduce the diameter of a portion of opening 21, but the present invention is not limited to this.

[0031] Second pressing portion 23 is disposed closer to one end of case 20 (i.e., the opening side) than first pressing portion 22, and presses the edge of sealing body 30. In other words, second pressing portion 23 presses upper surface 30a of sealing body 30 in the vicinity of opening 21. Second pressing portion 23 in this embodiment is formed by curling a portion of opening 21, but is not limited to this.

[0032] As shown in FIGS. 1 and 2, a slit 31 is formed in the upper surface 30a of the sealing body 30. The slit 31 extends radially inward of the case 20 beyond the second pressing portion 23 and communicates with the space outside the case 20. The slit 31 may extend radially inward by 0.2 to 2.0 mm beyond the radially inner end of the second pressing portion 23, for example. The slit 31 extends along the radial direction of the case 20. However, the slit 31 does not have to extend along the radial direction of the case 20.

[0033] The slit 31 is open to the side surface of the sealing body 30. Here, the slit 31 is formed at the most protruding apex 22a of the first pressing portion 22 on the side surface of the sealing body 30. Location Above AreaThe vertex 22a of the first pressing portion 22 is an important portion for ensuring the airtightness of the case 20, and it is advantageous from the viewpoint of ensuring the airtightness that the slit 31 does not open there. The slit 31 does not open on the underside of the sealing body 30.

[0034] As shown in Fig. 2, in this embodiment, four slits 31 are provided, but the number of slits 31 may be three or less or five or more. The four slits 31 are arranged at equal intervals (every 90° in this example) in the circumferential direction of the case 20. However, the multiple slits 31 do not have to be arranged at equal intervals. Note that through holes for passing the lead tabs 12A and 12B are not shown in Fig. 2.

[0035] The portion of opening 21 closer to the opening than vertex 22a of first pressing portion 22 may not be in partial contact with sealing body 30. That is, on the opening side closer to vertex 22a of first pressing portion 22, a gap may exist between the inner surface of opening 21 and the side surface of sealing body 30. If this gap exists, slit 31 may be in communication with the gap.

[0036] The depth of the slit 31 (the length in the direction parallel to the axial direction of the case 20) is the distance from the top surface of the sealing body 30 to the apex 22a of the first pressing portion 22. Location The distance to the case 20 may be D, and may be, for example, 0.25×D to 0.9×D. In this embodiment, the distance D may be, for example, 2 to 5 mm. The width of the slit 31 (the length in the circumferential direction of the case 20) may be, for example, 0.2 to 0.5 mm.

[0037] Slit 31 allows communication between the inside and outside of case 20 when the force acting from sealing body 30 on first pressing portion 22 falls below a predetermined value due to an increase in the internal pressure of case 20. On the other hand, slit 31 does not allow communication between the inside and outside of case 20 when the acting force is equal to or greater than the predetermined value.

[0038] 3, when the internal pressure of the case 20 increases, the sealing body 30 expands in the axial direction of the case 20 toward the outside of the case 20. When this axial expansion occurs, the area of ​​the sealing body 30 that is in contact with the first pressing portion 22 is displaced in a direction away from the first pressing portion 22 (i.e., radially inward), thereby weakening the force (elastic repulsive force against compression) acting from the sealing body 30 on the first pressing portion 22. When this acting force weakens to a value below a predetermined value, gas inside the case 20 passes between the sealing body 30 and the first pressing portion 22. This gas escapes from inside the case 20 to outside the case 20 through the slits 31, thereby ensuring the safety of the electricity storage device 10. [Example]

[0039] The relationship between the depth of the slit 31 and the operating pressure of the explosion-proof mechanism was measured for the electricity storage devices 10 of Examples 1 to 3 and Comparative Examples 1 and 2 shown below. Here, the operating pressure of the explosion-proof mechanism refers to the internal pressure of the case 20 when the inside and outside of the case 20 communicate with each other via the slit 31 as the internal pressure of the case 20 increases.

[0040] Example 1 The outer diameter of the aluminum case 20 was 18 mm, the axial length of the case 20 before the formation of the first pressing portion 22 and the second pressing portion 23 was 70 mm, and the axial distance from the upper surface 30a of the sealing body 30 to the apex 22a of the first pressing portion 22 was 3.5 mm. The thickness of the butyl rubber sealing body 30 was 7 mm, and the outer diameter of the sealing body 30 before compression was 17.1 mm. The width of the slit 31 was 0.3 mm, and the depth of the slit 31 was 1.11 mm. The operating pressure of the explosion-proof mechanism was 2.15 MPa.

[0041] Example 2 The depth of the slit 31 was set to 2.56 mm, and the other configurations were the same as those in Example 1. The operating pressure of the explosion-proof mechanism was 1.94 MPa.

[0042] Example 3 The depth of the slit 31 was set to 3.20 mm, and the other configurations were the same as those in Example 1. The operating pressure of the explosion-proof mechanism was 1.86 MPa.

[0043] Comparative Example 1 The depth of the slit 31 was set to 3.87 mm, and the other configurations were the same as those in Example 1. The operating pressure of the explosion-proof mechanism was 0.42 MPa.

[0044] Comparative Example 2 The depth of the slit 31 was set to 5.09 mm, and the other configurations were the same as those in Example 1. The operating pressure of the explosion-proof mechanism was 0.19 MPa.

[0045] As described above, a large difference was observed in the operating pressure of the explosion-proof mechanism between Examples 1 to 3 and Comparative Examples 1 and 2. As long as the desired operation can be obtained, a higher operating pressure of the explosion-proof mechanism is preferable, and it can be said that Examples 1 to 3 demonstrate the superiority of the explosion-proof mechanism. [Industrial Applicability]

[0046] The present disclosure can be used in an electricity storage device. [Explanation of symbols]

[0047] 10: Energy storage device 11: Energy storage element 12A, 12B: Lead tab 13A, 13B: Lead wire 20: Case 21: Opening 22: First pressing part 22a: Vertex 23: Second pressing part 30: Sealing body 30a:Top surface 31: Slit

Claims

1. A storage element; a cylindrical case having a bottom and an opening at one end, the case housing the storage element; a sealing body that seals the opening and contains an elastic resin, the case has a first pressing portion and a second pressing portion in the vicinity of the opening, the first pressing portion presses against a side surface of the sealing body and protrudes toward the inside of the case, the second pressing portion presses the upper surface of the sealing body, The sealing body has a slit on the top surface of the sealing body, the slit extends radially inward of the case beyond the second pressing portion and opens to a side surface of the sealing body, The sealing body is configured to deform in response to an increase in internal pressure of the case so as to form a gap at the first pressing portion between the side of the sealing body and the inner surface of the case, allowing gas inside the case to escape to the outside, while maintaining the lower surface of the sealing body opposite the upper surface positioned below the first pressing portion.

2. The power storage device according to claim 1 , wherein the slit is open only in a region above the most protruding apex of the first pressing portion on the side surface of the sealing body.

3. The power storage device according to claim 1 , wherein the sealing body has a plurality of slits, each of which is the slit.

4. The power storage device according to claim 3 , wherein the plurality of slits are arranged at equal intervals in a circumferential direction of the case.

5. An energy storage device as described in claim 1, further comprising an anode lead tab and a cathode lead tab connected to the anode and cathode of the energy storage element, respectively, and penetrating the sealing body.

6. The energy storage device described in claim 1, wherein the case is formed from aluminum, iron, or nickel.

7. The entire area of ​​the upper surface of the sealing body covered by the case, except for the area of ​​the slit, is in contact with the second pressing portion, The power storage device according to claim 1 , wherein a gap exists between the side surface of the sealing body and the inner surface of the case at a position above the position of the most protruding apex of the first pressing portion.

8. The entire area of ​​the upper surface of the sealing body covered by the case, except for the area of ​​the slit, is in contact with the second pressing portion, 2. The energy storage device according to claim 1, wherein in a cross section including the center of the sealing body and the center of the energy storage element, there is an empty area surrounded by the second pressing portion, a portion of the case above the most protruding apex of the first pressing portion, and the side surface of the sealing body.

9. An energy storage device as described in claim 1, wherein the slit extends radially inward by 0.2 mm or more and 2.0 mm or less than the radially inner end of the second pressing portion.

10. An energy storage device as described in claim 1, wherein when the distance from the upper surface of the sealing body to the position of the most protruding vertex of the first pressing portion is D, the depth of the slit is 0.25 x D or more and 0.9 x D or less.

11. An energy storage device as described in claim 1, wherein when the distance from the upper surface of the sealing body to the position of the most protruding vertex of the first pressing portion is D, the depth of the slit is 0.31 x D or more and 0.9 x D or less.

12. An energy storage device as described in claim 1, wherein the sealing body is configured so that the upper surface of the sealing body deforms to protrude toward the outside of the case due to an increase in internal pressure of the case.

13. An energy storage device as described in claim 1, wherein the sealing body is configured so that the lower surface of the sealing body deforms to protrude toward the outside of the case due to an increase in internal pressure of the case.

14. A lead tab connects to the storage element, a lead wire connected to the lead tab and thinner than the lead tab; The power storage device according to claim 1 , wherein the lead tab protrudes from the sealing body.

15. A storage element; a cylindrical case having a bottom and an opening at one end, the case housing the storage element; a sealing body that seals the opening and contains an elastic resin, the case has a first pressing portion and a second pressing portion in the vicinity of the opening, the first pressing portion presses against a side surface of the sealing body and protrudes toward the inside of the case, the second pressing portion presses the upper surface of the sealing body, The sealing body has a slit on the top surface of the sealing body, the slit extends radially inward of the case beyond the second pressing portion and opens to a side surface of the sealing body, The first pressing portion presses only a vertically middle portion of the side surface of the sealing body.

Images