End cap assembly, battery cell, battery pack, and electric device

Abstract

This application discloses an end cap assembly, a battery cell, a battery pack, and an electrical device. The end cap assembly includes an end cap, a stepped structure, a protrusion, and a pressure relief plate. The end cap has a pressure relief hole, and the stepped structure protrudes from the outer surface of the end cap and surrounds the pressure relief hole. The stepped structure includes a mounting surface. The protrusion protrudes from the inner surface of the end cap and surrounds the pressure relief hole. The pressure relief plate is mounted on the mounting surface and covers the pressure relief hole. The end cap with the stepped structure and protrusion can disperse stress during the formation of the pressure relief hole, making the end cap less prone to deformation. Furthermore, after the pressure relief hole is formed, it strengthens the structural strength of the end cap around the pressure relief hole, making the end cap less prone to deformation, thereby improving the problem of deformation easily occurring in the area of ​​the end cap near the pressure relief hole.

Description

Technical Field

[0001] This application belongs to the field of battery cell technology, and specifically relates to an end cap assembly, a battery cell, a battery pack, and an electrical device. Background Technology

[0002] With the widespread adoption of new energy vehicles and large-scale energy storage systems, the severity of thermal runaway in battery cells increases with energy density, placing higher demands on the safety and reliability of battery cells during thermal runaway. A battery cell consists of an end cap assembly and a core. The end cap assembly includes an end cap and a pressure relief component connected to the end cap. Under normal circumstances, the pressure relief component covers the pressure relief hole on the end cap. When thermal runaway occurs in the battery cell, and the pressure inside the containment cavity exceeds the safe range, the pressure relief component opens the pressure relief hole to release the pressure inside the containment cavity.

[0003] Because the end cap has a pressure relief hole, the strength of the end cap around the pressure relief hole is low. When the end cap is subjected to force, the area of ​​the end cap near the pressure relief hole is prone to deformation, which affects the assembly and use of the battery cell. Utility Model Content

[0004] This application provides an end cap assembly, a battery cell, a battery pack, and an electrical device, aiming to improve the problem of deformation easily occurring in the area of ​​the end cap near the pressure relief hole.

[0005] Embodiments of this application provide an end cap assembly, including an end cap, a stepped structure, a protrusion, and a pressure relief plate. The end cap has a pressure relief hole, the stepped structure protrudes from the outer surface of the end cap and surrounds the pressure relief hole, and the stepped structure includes a mounting surface. The protrusion protrudes from the inner surface of the end cap and surrounds the pressure relief hole. The pressure relief plate is mounted on the mounting surface and covers the pressure relief hole.

[0006] In the aforementioned end cap assembly, the pressure relief plate installed on the mounting surface, which covers the protrusions on the inner surface of the end cap and the stepped structure protruding from the outer surface of the end cap, increases the structural strength of the end cap around the pressure relief hole. This prevents the end cap from deforming or cracking during the formation of the pressure relief hole and during pressure relief. During the formation of the required pressure relief hole, the stepped structure and protrusions on both sides of the end cap disperse stress, preventing stress concentration that could lead to deformation or cracking of the end cap around the pressure relief hole. Therefore, the stepped structure and protrusions on both sides of the end cap disperse stress during the formation of the pressure relief hole, preventing deformation, and also strengthen the structural strength of the end cap around the pressure relief hole after its formation, thus improving the problem of deformation in the area near the pressure relief hole.

[0007] In some embodiments, the step structure includes a first step portion and a second step portion, the second step portion being disposed outside the first step portion and protruding from the first step portion, and the mounting surface being disposed on the first step portion; the protrusion is corresponding to the first step portion along the extension direction of the pressure relief hole.

[0008] The second step protrudes from the mounting surface of the first step to form a stepped structure, with the protrusion corresponding to the first step so that the protrusion surrounds the pressure relief hole.

[0009] In some embodiments, the second step portion includes a stop surface and a top surface, the stop surface being configured to abut against the side surface of the pressure relief sheet in the mounting surface, and the top surface of the second step portion being coplanar with the side of the pressure relief sheet facing away from the mounting surface or protruding from the pressure relief sheet.

[0010] The pressure relief plate is sealed against the side surface of the stop surface to increase its sealing effect on the cavity; the top surface of the second step protrudes from the pressure relief plate to protect it from being damaged by impact.

[0011] In some embodiments, the step structure further includes a third step portion, which is disposed outside the second step portion and protrudes beyond the second step portion.

[0012] The third step further reinforces the end cap around the pressure relief hole, increasing the strength of the end cap near the pressure relief hole area and making it less prone to deformation and cracking. When the pressure relief plate is installed on the mounting surface, the third step protrudes from the pressure relief plate to protect it and prevent it from being damaged by external impacts.

[0013] In some embodiments, the sides of the second and third steps closest to the protrusion are coplanar with the inner surface of the end cap.

[0014] The second and third steps are easily integrated with the end cap, and the protrusions protrude from the inner surface of the end cap. The step structure is set on the same side as the inner surface of the end cap, so that the protrusions can support and hold the electrode core to prevent electrolyte from flowing into the pressure relief hole.

[0015] In some embodiments, the end cap includes a lower cover and a sidewall. The lower cover is connected to one end of the sidewall to form a receiving cavity with an opening together with the sidewall. A pressure relief hole is provided in the lower cover, and the lower cover and the opening of the receiving cavity are disposed opposite to each other along the extending direction of the pressure relief hole.

[0016] When the pressure inside the containment chamber exceeds the safe range and the pressure relief plate is ejected, the pressure relief hole located on the lower cover can prevent the ejected material from being ejected upward and causing secondary damage.

[0017] Embodiments of this application also provide a battery cell, including the end cap assembly as described in the previous embodiment.

[0018] The battery cell described above uses the end cap assembly from the previous embodiment. The end cap assembly is less prone to deformation or cracking, resulting in better safety performance and a longer service life for the battery cell.

[0019] Embodiments of this application also provide a battery pack, including a housing and battery cells as described in the previous embodiment, the housing having a receiving space in which multiple battery cells are disposed.

[0020] In the aforementioned battery pack, multiple battery cells are arranged within a housing space to form the battery pack, thereby meeting higher energy demands. The end cap assembly is not prone to deformation or cracking, resulting in better battery pack safety performance and a longer service life.

[0021] In some embodiments, the housing is provided with through holes, each through hole corresponding to a pressure relief hole; in each cell, the stepped structure includes a third stepped portion disposed around the pressure relief hole, and a sealing ring is sleeved on the outer periphery of the third stepped portion, and when the cell is disposed in the receiving space, the sealing ring is configured to abut against the inner surface of the housing.

[0022] The sealing rings hold the bottom of the lower cover and the outer casing respectively to seal the gap between the lower cover and the outer casing. When the battery cell ejects material through the pressure relief hole and the through hole, the sealing rings can prevent the ejected material from flowing back into the receiving space.

[0023] Embodiments of this application also provide an electrical device, including a battery pack as in the previous embodiment or a battery cell as in another embodiment.

[0024] In the aforementioned electrical device, the battery pack described above is used. The battery pack uses a sealing ring to prevent ejected material from entering the containment space, thereby ensuring the safety and service life of the battery pack and thus improving the safety of the electrical device. Attached Figure Description

[0025] Figure 1 This is a perspective view of the battery cell in one embodiment of this application.

[0026] Figure 2 yes Figure 1 Exploded view of China Electronics Cell.

[0027] Figure 3 yes Figure 1 A 3D view of the cut-out end cap assembly of the CNC cell.

[0028] Figure 4 yes Figure 3 Cross-sectional view of the middle end cap assembly.

[0029] Figure 5 yes Figure 1 A partial schematic diagram of the battery cell installed in the casing.

[0030] Explanation of main component symbols

[0031] 100. End cap assembly; 101. Receiving cavity; 10. End cap; 11. Lower cap; 111. Pressure relief hole; 12. Side wall; 20. Stepped structure; 21. First step portion; 211. Mounting surface; 212. Bottom surface; 22. Second step portion; 221. Stop surface; 222. Top surface; 23. Third step portion; 30. Protrusion; 40. Pressure relief plate; 200. Battery cell; 210. Electrode core; 220. Upper cover assembly; 2201. Liquid injection structure; 300. Outer shell; 310. Through hole; 320. Sealing ring; Z, First direction.

[0032] The following detailed description, in conjunction with the accompanying drawings, will further illustrate this application. Detailed Implementation

[0033] The technical solutions of the embodiments of this application will be described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments.

[0034] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

[0035] Embodiments of this application provide an end cap assembly for a battery cell, including an end cap, a stepped structure, a protrusion, and a pressure relief plate. The end cap has a pressure relief hole, the stepped structure protrudes from the outer surface of the end cap and surrounds the pressure relief hole, and the stepped structure includes a mounting surface. The protrusion protrudes from the inner surface of the end cap and surrounds the pressure relief hole. The pressure relief plate is mounted on the mounting surface and covers the pressure relief hole.

[0036] In the aforementioned end cap assembly, the pressure relief plate installed on the mounting surface, which covers the protrusions on the inner surface of the end cap and the stepped structure protruding from the outer surface of the end cap, increases the structural strength of the end cap around the pressure relief hole. This prevents the end cap from deforming or cracking during the formation of the pressure relief hole and during pressure relief. During the formation of the required pressure relief hole, the stepped structure and protrusions disperse stress, preventing stress concentration that could lead to deformation or cracking of the end cap around the pressure relief hole. Therefore, the end cap with the stepped structure and protrusions disperses stress during the formation of the pressure relief hole, preventing deformation, and strengthens the structural strength of the end cap around the pressure relief hole after its formation, thus mitigating the problem of deformation in the area near the pressure relief hole.

[0037] The embodiments of this application will be further described below with reference to the accompanying drawings. Unless otherwise specified, the various embodiments in this application can be combined with each other.

[0038] Please combine Figure 1 and Figure 2 An embodiment of this application provides an end cap assembly 100, including a receiving cavity 101 with an opening, the receiving cavity 101 for receiving an electrode core 210, so that the electrode core 210, the end cap assembly 100 and the top cover assembly 220 can together form a battery cell 200.

[0039] In some embodiments, the battery cell 200 can be used in an electrical device, which may include a small portable device, an energy storage device, or other power-consuming device, and this application does not limit this.

[0040] In some embodiments, multiple battery cells 200 can form a battery pack. The battery pack can be used in electrical devices, including processing appliances, power tools, or vehicles, etc., and this application does not impose any limitations on this.

[0041] Please combine Figure 2 and Figure 3 In an embodiment of this application, the end cap assembly 100 includes an end cap 10, a stepped structure 20, and a pressure relief plate 40. The end cap 10 forms a receiving cavity 101 with an opening, and the end cap 10 has a pressure relief hole 111 communicating with the receiving cavity 101. The stepped structure 20 is disposed on the end cap 10, protruding from the outer surface of the end cap 10 and coaxially surrounding the pressure relief hole 111. The pressure relief plate 40 is mounted on the stepped structure 20 to cover the pressure relief hole 111, thereby sealing the receiving cavity 101. The stepped structure 20 is integrally formed on the end cap 10.

[0042] When the pressure inside the receiving cavity 101 exceeds the safe range, the pressure relief plate 40 is ejected, that is, the pressure relief plate 40 is disengaged from the stepped structure 20 and the pressure relief hole 111, so that the pressure inside the receiving cavity 101 can be released through the pressure relief hole 111, thereby improving the explosion-proof performance and safety of the battery cell 200.

[0043] The end cap assembly 100 also includes a protrusion 30 that protrudes from the inner surface of the end cap 10 and is coaxially arranged around the pressure relief hole 111.

[0044] The extension direction of the pressure relief hole 111 is defined as the first direction Z. The outer surface and inner surface of the end cap 10 refer to the two opposite sides of the end cap 10 along the first direction Z.

[0045] The end cap 10 is made of aluminum. During the formation of the required pressure relief hole 111, the end cap 10 is at a high temperature, meaning it is in a flowable state. After the end cap 10 is formed, it hardens and becomes non-flowable. To form the required pressure relief hole 111, a small hole is first made in the end cap 10. Then, a stepped structure 20 is formed in the end cap 10. The flowability of the aluminum material is then used to enlarge the hole, finally obtaining the required pressure relief hole 111. During the formation of the required pressure relief hole 111, the stepped structure 20 and protrusions 30 located on both sides of the end cap 10 disperse the stress around the pressure relief hole 111, preventing stress concentration from causing deformation or cracking of the end cap 10 around the pressure relief hole 111. After the required pressure relief hole 111 is formed, the end cap 10 is hardened. The step structure 20 and protrusion 30 respectively provided on both sides of the end cap 10 can support the end cap 10, so as to reinforce the end cap 10 around the pressure relief hole 111 and make the area of ​​the end cap 10 near the pressure relief hole 111 less prone to deformation or cracking.

[0046] Therefore, the stepped structure 20 and the protrusion 30 respectively provided on both sides of the end cap 10 can disperse stress during the formation of the pressure relief hole 111, making the end cap 10 less prone to deformation. They can also strengthen the structural strength of the end cap 10 around the pressure relief hole 111 after the pressure relief hole 111 is formed, making the end cap 10 less prone to deformation, thereby improving the problem that the area of ​​the end cap 10 near the pressure relief hole 111 is prone to deformation.

[0047] In some embodiments, the pressure relief plate 40 is fixed to the mounting surface 211 by adhesive bonding or welding.

[0048] Please see Figure 2 In some embodiments, the end cap 10 includes a lower cover 11 and a side wall 12. Along a first direction Z, the lower cover 11 is connected to one end of the side wall 12, such that the lower cover 11 and the side wall 12 together form a receiving cavity 101 with an opening, and the lower cover 11 and the opening of the receiving cavity 101 are disposed opposite each other along the first direction Z. In the illustrated embodiment, the first direction Z is the height direction of the end cap 10, that is, the first direction Z is the vertical direction.

[0049] In some embodiments, the pressure relief hole 111 is provided on the lower cover 11, that is, the stepped structure 20 protrudes from the side of the lower cover 11 facing away from the side wall 12 in the first direction Z, and the protrusion 30 protrudes from the side of the lower cover 11 connected to the side wall 12 in the first direction Z.

[0050] When the electrode core 210 is located in the receiving cavity 101 and the battery cell 200 is installed on the main body of the device, the protrusion 30 protruding from the inner surface of the lower cover 11 supports and abuts the electrode core 210.

[0051] Understandably, the battery cell 200 is filled with electrolyte, which tends to settle at the bottom of the receiving cavity 101, i.e., the lower cover 11. The protrusion 30 protruding from the inner surface of the lower cover 11 supports the electrode core 210, raising the position of the electrode core 210 within the receiving cavity 101 and preventing the bottom of the electrode core 210 from being immersed in the electrolyte sediment for a long time, thus affecting the performance and lifespan of the electrode core 210.

[0052] In some embodiments, the stepped structure 20 includes a first stepped portion 21 and a second stepped portion 22. The first stepped portion 21 is disposed around the outer periphery of the pressure relief hole 111. The second stepped portion 22 is disposed around the outer side of the first stepped portion 21. Along the first direction Z, the second stepped portion 22 protrudes from the first stepped portion 21 to form a stepped structure 20 in the form of a step.

[0053] The mounting surface 211 is provided on the first step portion 21. Along the first direction Z, the protrusion 30 corresponds to the first step portion 21, that is, the protrusion 30 and the first step portion 21 are both arranged around the pressure relief hole 111.

[0054] The protrusion 30 surrounding the pressure relief hole 111 protrudes from the inner surface of the lower cover 11, which can increase the structural strength of the lower cover 11 around the pressure relief hole 111, so that the end cover assembly 100 is not easily deformed and broken when the lower cover 11 forms the pressure relief hole 111 and when the battery cell 200 is depressurized.

[0055] In some embodiments, the second step portion 22 includes a stop surface 221 and a top surface 222. When the pressure relief plate 40 is fixedly installed on the mounting surface 211, the stop surface 221 abuts against the side surface of the pressure relief plate 40 so that the pressure relief plate 40 completely covers the pressure relief hole 111, increasing the sealing effect of the pressure relief plate 40 on the receiving cavity 101; and the top surface 222 of the second step portion 22 is coplanar with the side of the pressure relief plate 40 facing away from the mounting surface 211, or protrudes from the pressure relief plate 40, to protect the pressure relief plate 40 from being damaged by impact. When the top surface 222 protrudes from the pressure relief plate 40, it can better protect the pressure relief plate 40 from being damaged by impact.

[0056] In some embodiments, the stop surface 221 is perpendicular to the top surface 222 to adapt to the pressure relief plate 40, so that the stop surface 221 can fit with the side surface of the pressure relief plate 40.

[0057] Please see Figure 3 In some embodiments, the step structure 20 further includes a third step portion 23, which surrounds the outer periphery of the second step portion 22 and protrudes from the top surface 222 of the second step portion 22 in the first direction Z.

[0058] The third step 23 further reinforces the lower cover 11 around the pressure relief hole 111, increasing the strength of the area near the pressure relief hole 111 and making the end cover 10 less prone to deformation and cracking. When the pressure relief plate 40 is fixedly installed on the mounting surface 211, the third step 23 protects the pressure relief plate 40 and prevents it from being damaged by external impacts.

[0059] In some embodiments, along the first direction Z, the side of the second step portion 22 and the third step portion 23 near the protrusion 30 is coplanar with the inner surface of the lower cover 11, so that the second step portion 22 and the third step portion 23 are integrally formed with the end cover 10.

[0060] The second step portion 22 and the third step portion 23 are both coplanar with the inner surface of the lower cover 11 on one side inside the receiving cavity 101. The protrusion 30 protrudes from the inner surface of the lower cover 11, which enables the first step portion 21 to both improve the structural strength of the lower cover 11 around the pressure relief hole 111 and prevent electrolyte from settling into the pressure relief hole 111.

[0061] Understandably, when the electrode core 210 is installed on the end cap assembly 100 to form the battery cell 200, some electrolyte may easily settle at the bottom of the receiving cavity 101, i.e., the lower cover 11. By having the protrusion 30 surrounding the outer periphery of the pressure relief hole 111 and protruding from the inner surface of the lower cover 11 against the electrode core 210, the electrolyte settled at the bottom of the receiving cavity 101 can be prevented from flowing into the pressure relief hole 111, thereby preventing the electrolyte from clogging the pressure relief hole 111.

[0062] Please see Figure 4 In some embodiments, along the first direction Z, the thickness of the first step portion 21 is defined as H1, the thickness of the second step portion 22 is defined as H2, and the thickness of the third step portion 23 is defined as H3, where H3 > H2 > H1.

[0063] During the formation of the pressure relief hole 111, the thinnest first step portion 21 can preferentially absorb the pressure of deformation, absorb processing errors, and disperse stress to prevent stress concentration from causing the lower cover 11 to crack; the thickest third step portion 23 is the most robust and can provide rigid support for the area of ​​the lower cover 11 near the pressure relief hole 111, thereby preventing the lower cover 11 from undergoing overall deformation or cracking; the second step portion 22 can serve as a transition between the first step portion 21 and the third step portion 23, further homogenizing the stress distribution.

[0064] After the pressure relief hole 111 is formed, the end cap 10 hardens. The first step portion 21, the second step portion 22 and the third step portion 23, which gradually increase in thickness, surround the pressure relief hole 111. They can disperse local stress and suppress cracking of the end cap 10 by step-by-step thickening. This makes the end cap 10 stronger around the pressure relief hole 111 than the ordinary flat-mouth structure, so as to prevent the end cap 10 from deforming and cracking.

[0065] In some embodiments, along the first direction Z, the mounting surface 211 of the first step portion 21 is recessed into the outer surface of the lower cover 11, that is, the mounting surface 211 is lower than the outer surface of the lower cover 11, so that the thickness of the first step portion 21 is thinner, so as to avoid the thickness of the gradually thickening second step portion 22 and third step portion 23 being too large.

[0066] Please combine Figure 3 and Figure 4 In some embodiments, the pressure relief hole 111 is circular, racetrack-shaped, elliptical, or square. In the illustrated embodiment, the pressure relief hole 111 is racetrack-shaped.

[0067] Please see Figure 1 and Figure 2 The embodiments of this application also provide a battery cell 200, which includes the end cap assembly 100 in the previous embodiment.

[0068] The battery cell 200 also includes an electrode core 210 and a cover assembly 220. The electrode core 210 is disposed in the receiving cavity 101, and the cover assembly 220 is connected to the end cap 10, specifically connected to the end of the side wall 12 near the opening along the first direction Z, so that the cover assembly 220 closes the opening of the receiving cavity 101.

[0069] In the battery cell 200, the end cap assembly 100 is connected to the upper cover assembly 220 to encapsulate the electrode core 210 within the receiving cavity 101. The stepped structure 20 and the protrusion 30 respectively provided on both sides of the lower cover 11 give the end cap 10 of the end cap assembly 100 greater structural strength in the area near the pressure relief hole 111. When the pressure inside the receiving cavity 101 increases, the end cap 10 is less likely to deform or crack, resulting in better safety performance and a longer service life for the battery cell 200.

[0070] In some embodiments, the top cover assembly 220 is provided with a liquid injection structure 2201, which is configured to connect to a liquid injection machine, so that the liquid injection machine can inject electrolyte into the electrode core 210 in the receiving cavity 101 through the liquid injection structure 2201, so that the electrolyte wets the internal pores of the electrode core 210 (such as the micropores of the electrode and the diaphragm).

[0071] During installation, the electrode core 210 is first installed in the receiving cavity 101, then the upper cover assembly 220 is welded to the side wall 12, and finally the electrolyte is injected into the electrode core 210 through the liquid injection structure 2201.

[0072] Please see Figure 5 Embodiments of this application also provide a battery pack (not shown), including a housing 300 and a plurality of battery cells 200 as in the previous embodiment. The housing 300 has a receiving space in which the plurality of battery cells 200 are installed.

[0073] Multiple battery cells 200 are installed in the housing space of the casing 300 to form a battery pack, which can meet higher energy requirements. The stepped structure 20 and the protrusion 30 make the end cover 10 of the end cover assembly 100 have greater structural strength in the area near the pressure relief hole 111. When the pressure in the housing cavity 101 increases, the end cover 10 is not easy to deform or crack, which makes the battery pack safer and has a longer service life.

[0074] In some embodiments, the bottom of the housing 300 is provided with a through hole 310. Each through hole 310 corresponds to a pressure relief hole 111. A sealing ring 320 is fitted around the outer periphery of the third step portion 23. When the battery cell 200 is disposed in the receiving space, the sealing ring 320 is configured to abut against the inner surface of the housing 300.

[0075] When the pressure inside the receiving cavity 101 exceeds the safe range, the pressure relief plate 40 is ejected, causing the electrode core 210 to release pressure through the pressure relief hole 111. The ejected material from the electrode core 210 is ejected through the pressure relief hole 111 and the through hole 310.

[0076] The sealing rings 320 abut against the bottom of the lower cover 11 and the outer shell 300 respectively to seal the gap between the lower cover 11 and the outer shell 300, thereby preventing the ejected material from flowing back into the gap between the lower cover 11 and the outer shell 300, that is, preventing the ejected material from entering the receiving space.

[0077] Embodiments of this application also provide an electrical device, including a device body and a battery pack as described in the previous embodiment. The battery pack is installed in the device body and provides electrical power to the device body. The electrical device is a vehicle, and the device body is the vehicle body.

[0078] The electrical devices using the aforementioned battery pack have better battery pack safety and longer service life, thus ensuring better safety for the electrical devices.

[0079] Furthermore, those skilled in the art should recognize that the above embodiments are merely illustrative of this application and are not intended to limit this application. Any appropriate changes and variations made to the above embodiments within the essential spirit and scope of this application fall within the scope of this application's disclosure.

Claims

1. An end cap assembly, characterized in that, The end cap assembly includes: End cap, equipped with pressure relief hole; A stepped structure protrudes from the outer surface of the end cap and surrounds the pressure relief hole; the stepped structure includes a mounting surface. A protrusion protrudes from the inner surface of the end cap and surrounds the pressure relief hole; A pressure relief plate is installed on the mounting surface and covers the pressure relief hole.

2. The end cap assembly as claimed in claim 1, characterized in that, The step structure includes a first step portion and a second step portion, the second step portion is disposed on the outside of the first step portion and protrudes from the first step portion, and the mounting surface is disposed on the first step portion; Along the extending direction of the pressure relief hole, the protrusion corresponds to the first stepped portion.

3. The end cap assembly as described in claim 2, characterized in that, The second step portion includes a stop surface and a top surface. The stop surface is configured to abut against the side surface of the pressure relief sheet in the mounting surface. The top surface of the second step portion is coplanar with the side of the pressure relief sheet facing away from the mounting surface, or protrudes from the pressure relief sheet.

4. The end cap assembly as claimed in claim 2, characterized in that, The stepped structure also includes a third stepped portion, which is located outside the second stepped portion and protrudes from the second stepped portion.

5. The end cap assembly as claimed in claim 4, characterized in that, The second and third stepped portions are both coplanar with the inner surface of the end cap on the side closest to the protrusion.

6. The end cap assembly as claimed in claim 1, characterized in that, The end cap includes a lower cover and a side wall. The lower cover is connected to one end of the side wall to form an open receiving cavity together with the side wall. The pressure relief hole is provided on the lower cover, and the lower cover and the opening of the receiving cavity are arranged opposite to each other along the extending direction of the pressure relief hole.

7. A battery cell, characterized in that, Includes the end cap assembly as described in any one of claims 1 to 6.

8. A battery pack, characterized in that, include: The outer shell has a storage space; A plurality of battery cells as described in claim 7, wherein the plurality of battery cells are disposed in the receiving space.

9. The battery pack as described in claim 8, characterized in that, The outer casing is provided with multiple through holes, each of which corresponds to a pressure relief hole; In each of the battery cells, the stepped structure includes a third stepped portion surrounding the pressure relief hole, and a sealing ring is fitted around the outer periphery of the third stepped portion. When the battery cell is placed in the receiving space, the sealing ring is configured to abut against the inner surface of the housing.

10. An electrical device, characterized in that, This includes the battery pack as described in claim 8 or 9, or the battery cell as described in claim 7.

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