Top cover assembly, single battery cell and battery pack

Abstract

The utility model relates to the technical field of batteries, and provides a top cover assembly, a single battery cell and a battery pack. The top cover assembly comprises a cover plate, a liquid injection pipe and a one-way valve. And the cover plate is provided with a liquid injection hole. The liquid injection pipe is connected to the inner side of the cover plate and communicates with the liquid injection hole. The one-way valve is connected to the liquid injection pipe. The one-way valve is configured to allow liquid to flow in the direction from the liquid injection hole to the liquid injection pipe. Therefore, the electrolyte in the single battery cell can be prevented from leaking or spraying out from the liquid injection pipe and the liquid injection hole, the electrolyte is prevented from being wasted, and the electrolyte is prevented from influencing the production environment and harming the health of staff after being sprayed and leaked.

Description

Technical Field

[0001] This utility model relates to the field of battery technology, specifically to a top cover assembly, a single battery cell, and a battery pack. Background Technology

[0002] In related technologies, electrolyte is typically injected into individual battery cells through injection holes in the cover plate using an injection needle. When the injection needle is removed, leakage or spraying of electrolyte can occur because the powder and diaphragm inside the individual battery cell do not absorb the electrolyte in time. Electrolyte leakage not only wastes raw materials, but the volatile nature of the electrolyte also affects the production environment and endangers the health of employees. Utility Model Content

[0003] The embodiments of this utility model provide a top cover assembly, a single battery cell, and a battery pack. A one-way valve is used to ensure that the electrolyte can only be injected into the single battery cell through the injection hole, thereby preventing leakage and spraying.

[0004] In a first aspect, embodiments of the present invention provide a top cover assembly. The top cover assembly includes:

[0005] The cover plate is equipped with an injection hole;

[0006] The injection tube is connected to the inside of the cover plate, and the injection tube is in communication with the injection hole;

[0007] A one-way valve, connected to the injection tube, is configured to allow liquid to flow in the direction from the injection port to the injection tube.

[0008] In one embodiment, the one-way valve includes:

[0009] A valve cover is rotatably connected to the end of the injection tube furthest from the cover plate;

[0010] A support member, connected to the valve cover, is configured to apply a force to the valve cover so that the valve cover closes the injection tube under the action of the force.

[0011] In one embodiment, the top cover assembly further includes:

[0012] A chemically formed pin is detachably installed in the injection hole. A channel is formed inside the chemically formed pin. The chemically formed pin is configured to open the one-way valve and connect the inside and outside of the cover plate through the channel.

[0013] In one embodiment, the aperture of the channel is D, which satisfies: 0.5 mm ≤ D ≤ 3 mm.

[0014] In one embodiment, the length of the chemically formed nail is L1, and the sum of the depths of the injection hole and the injection tube is L2, satisfying: L1 > L2.

[0015] In one embodiment, the following condition is satisfied: 1 mm ≤ L1 - L2 ≤ 7 mm.

[0016] In one embodiment, the chemically formed nail includes a first segment and a second segment. The outer diameter of the first segment is less than or equal to the diameter of the injection hole and the outer diameter of the first segment is less than or equal to the diameter of the injection tube. The outer diameter of the second segment is greater than the diameter of the injection hole. The first segment is configured to pass through the injection hole into the injection tube and open the one-way valve.

[0017] In one embodiment, the second segment has an expanding sub-segment with an increasing outer diameter along the direction away from the cover plate.

[0018] Secondly, embodiments of this utility model provide a single battery cell, including the top cover assembly as described above.

[0019] Thirdly, embodiments of this utility model provide a battery pack, including the single battery cell as described above.

[0020] The beneficial effects of the embodiments of this utility model are as follows:

[0021] In this embodiment of the invention, a one-way valve is installed on the injection tube. When electrolyte is injected into the individual battery cell through the injection hole and injection tube, the one-way valve is in the open state, allowing the electrolyte to flow into the individual battery cell. After the injection is completed and the injection needle is removed, the one-way valve closes the injection tube. This prevents electrolyte from leaking or spraying out of the individual battery cell from the injection tube and injection hole, avoiding electrolyte waste and preventing electrolyte leakage from affecting the production environment and endangering employee health. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of this utility model, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 This is a schematic diagram of the cover plate provided in an embodiment of the present invention from a first-view perspective;

[0024] Figure 2 This is a schematic diagram of the cover plate provided in an embodiment of the present invention from a second perspective.

[0025] Figure 3 This is a cross-sectional view of the injection tube provided in an embodiment of this utility model;

[0026] Figure 4This is a cross-sectional view of the chemically formed nail provided in an embodiment of this utility model.

[0027] Figure label:

[0028] 10-Cover plate, 110-Injection hole, 20-Injection tube, 30-One-way valve, 310-Valve cover, 40-Chemicalization nail, 410-Channel, 420-First section, 430-Second section, 4310-Gradually expanding sub-section. Detailed Implementation

[0029] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present utility model. In addition, it should be understood that the specific embodiments described herein are only for illustration and explanation of the present utility model and are not intended to limit the present utility model. In the present utility model, unless otherwise stated, directional terms such as "upper" and "lower" generally refer to the upper and lower positions of the device in actual use or operation, specifically the drawing directions in the accompanying drawings; while "inner" and "outer" refer to the outline of the device.

[0030] Please see Figures 1 to 2 This application provides a top cover assembly. The top cover assembly includes a cover plate 10, a liquid injection pipe 20, and a one-way valve 30. The cover plate 10 has a liquid injection hole 110. The liquid injection pipe 20 is connected to the inner side of the cover plate 10 and communicates with the liquid injection hole 110. The one-way valve 30 is connected to the liquid injection pipe 20. The one-way valve 30 is configured to allow liquid to flow in the direction from the liquid injection hole 110 to the liquid injection pipe 20.

[0031] In this embodiment, by installing a one-way valve 30 on the injection tube 20, when electrolyte is injected into the individual battery cell through the injection hole 110 and the injection tube 20, the one-way valve 30 is in the open state, allowing the electrolyte to flow into the individual battery cell. After the injection is completed and the injection needle is removed, the one-way valve 30 closes the injection tube 20. This prevents the electrolyte inside the individual battery cell from leaking or spraying out from the injection tube 20 and the injection hole 110, avoiding electrolyte waste and preventing electrolyte leakage from affecting the production environment and endangering employee health.

[0032] In some embodiments, the cover plate 10 includes an aluminum plate and upper and lower plastic sheets located on the upper and lower sides of the aluminum plate, respectively. The aluminum plate, upper plastic sheet, and lower plastic sheet all have interconnected injection holes 110. The injection tube 20 can be integrally formed with the aluminum plate and communicate with the injection hole 110. Alternatively, the injection tube 20 can be integrally formed with the lower plastic sheet and communicate with the injection hole 110. Alternatively, the injection tube 20 can also be connected to the aluminum plate or lower plastic sheet by means of snap-fit ​​fixing, welding, heat fusion connection, etc.

[0033] It should be noted that the shape of the injection tube 20 can be the same as the shape of the injection hole 110. For example, the injection hole 110 is preferably a circular hole, then the injection tube 20 is a circular tube, and the diameter of the injection tube 20 is the same as the diameter of the injection hole 110.

[0034] In some embodiments, the one-way valve 30 is connected to the end of the injection tube 20 away from the injection port 110. Alternatively, the one-way valve 30 is located inside the injection tube 20.

[0035] In some embodiments, the top cover assembly is applied to a single battery cell. The single battery cell includes an electrode assembly. The side of the cover plate 10 facing the electrode assembly is the inner side of the cover plate 10, and the side of the cover plate 10 away from the electrode assembly is the outer side of the cover plate 10. When the valve cover 310 of the one-way valve 30 moves towards the electrode assembly, the one-way valve 30 switches from a closed state to an open state. When the valve cover 310 of the one-way valve 30 moves towards the injection tube 20, the one-way valve 30 switches from an open state to a closed state.

[0036] It should be noted that the one-way valve 30 can switch from a closed state to an open state under the action of the injection needle, and automatically return to the closed state after the injection needle is withdrawn. Alternatively, the one-way valve 30 can be controlled to open and close by a drive component. For example, during injection, the drive component controls the one-way valve 30 to switch from a closed state to an open state. When the injection is completed and the injection needle is withdrawn, the drive component controls the one-way valve 30 to switch from an open state to a closed state. The drive component includes, but is not limited to, a motor, a hydraulic rod, etc.

[0037] like Figure 3 As shown, in some embodiments, the one-way valve 30 includes a valve cover 310 and a support. The valve cover 310 is rotatably connected to the end of the injection tube 20 away from the cover plate 10. The support is connected to the valve cover 310. The support is configured to apply a force to the valve cover 310, causing the valve cover 310 to close the injection tube 20 under the action of the force.

[0038] Understandably, the support member provides force to the valve cover 310 to ensure that the valve cover 310 can close the injection tube 20. The shape of the valve cover 310 is adapted to the shape of the injection tube 20. The shape of the valve cover 310 is the same as that of the injection tube 20, and the size of the valve cover 310 is slightly larger than that of the injection tube 20. This allows the valve cover 310 to completely close the injection tube 20. For example, the injection tube 20 is a circular tube, and the valve cover 310 is a circular cap. Therefore, when the valve cover 310 is rotatably connected to the injection tube 20, it can completely close the injection tube 20.

[0039] It should be noted that the diameter of the valve cover 310 must be larger than the orifice of the injection tube 20 to ensure that the valve cover 310 can completely seal the end of the injection tube 20 away from the cover plate 10, and to ensure that the valve cover 310 cannot rotate into the injection tube 20, so as to prevent the one-way flow failure of the one-way valve 30 due to the valve cover 310 rotating into the injection tube 20.

[0040] In some embodiments, the support is a torsion spring. The valve cover 310 is rotatably mounted on the end of the injection tube 20 away from the cover plate 10 via a rotating seat and a rotating shaft. The torsion spring is sleeved on the rotating shaft and can apply a force to the valve cover 310 to rotate it towards the injection tube 20. When the valve cover 310 closes the injection tube 20, the torsion spring remains in a contracted state, allowing it to apply a force to the valve cover 310 to close the injection tube 20. Specifically, during the injection phase, after the injection needle abuts against the valve cover 310, as the needle continues to extend, it applies pressure to the valve cover 310. When this pressure exceeds the force exerted by the torsion spring on the valve cover 310, the valve cover 310 will rotate away from the injection tube 20. This switches the one-way valve 30 from a closed state to an open state. When the injection is complete and the injection needle is removed, the pressure of the injection needle on the valve cover 310 will disappear. At this time, the torsion spring, based on its own elastic self-returning mechanism, can drive the cover plate 10 to rotate towards the injection tube 20. This causes the one-way valve 30 to switch from the open state to the closed state.

[0041] In some embodiments, the support is configured as an elastic sheet, which can be connected to an extension of the injection tube 20 or other mounting structure of the lower plastic. The elastic sheet can be horizontally or obliquely disposed on the side of the valve cover 310 away from the injection tube 20. At least a portion of the elastic sheet abuts against the side of the valve cover 310 away from the injection tube 20, and the elastic sheet has a tendency to deform towards the injection tube 20. Thus, the elastic sheet can apply a force to the valve cover 310 to rotate towards the injection tube 20, enabling the valve cover 310 to close the injection tube 20. Specifically, during the injection phase, after the injection needle abuts against the valve cover 310, as the injection needle continues to extend, it applies pressure to the valve cover 310. When this pressure exceeds the force exerted by the elastic sheet on the valve cover 310, the valve cover 310 will rotate away from the injection tube 20. This switches the one-way valve 30 from a closed state to an open state. When the injection is complete and the injection needle is removed, the pressure of the injection needle on the valve cover 310 will disappear. At this time, the elastic plate, based on its own elastic self-recovery, can drive the cover plate 10 to rotate towards the injection tube 20. Thus, the one-way valve 30 switches from the open state to the closed state.

[0042] In some embodiments, the support member can also be configured as a torsion motor. The torsion motor can drive the valve cover 310 to rotate. The torsion motor is a worm gear motor. When the valve cover 310 closes the injection tube 20, the torsion motor can achieve self-locking of the torsion motor shaft through the worm gear structure, so as to ensure that the valve cover 310 can maintain the state of closing the injection tube 20. Specifically, during the injection stage, the torsion motor drives the valve cover 310 to rotate away from the injection tube 20, so that the one-way valve 30 switches from the closed state to the open state. After the injection is completed and the injection needle is pulled out, the torsion motor drives the cover plate 10 to rotate towards the injection tube 20, so that the one-way valve 30 switches from the open state to the closed state.

[0043] In some embodiments, the support member can also be configured as a telescopic rod. The telescopic rod is inclinedly disposed on the side of the valve cover 310 away from the injection tube 20. The telescopic rod may include a sleeve and a rod body, one end of which is slidably mounted within the sleeve, and a spring is disposed within the sleeve. When the telescopic rod retracts, the rod body gradually retracts into the sleeve, causing the spring to gradually contract. The end of the sleeve away from the rod body is connected to an extension of the injection tube 20 or other mounting structure on the lower plastic, and the end of the rod away from the sleeve is slidably connected to the side of the valve cover 310 away from the injection tube 20. When the valve cover 310 closes the injection tube 20, the spring remains in a contracted state, allowing the spring to exert a closing force on the valve cover 310 through the rod body. Specifically, during the injection phase, after the injection needle abuts against the valve cover 310, as the injection needle continues to extend, it applies pressure to the valve cover 310. When the pressure exceeds the force exerted by the spring on the valve cover 310, the valve cover 310 will rotate away from the injection tube 20. At this time, the rod slides on the valve cover 310 towards the rotating connection of the valve cover 310 and gradually retracts into the sleeve. This switches the one-way valve 30 from the closed state to the open state. When the injection is completed and the injection needle is removed, the pressure of the injection needle on the valve cover 310 will disappear. At this time, the spring, based on its own elastic self-returning, can drive the rod to extend out of the sleeve. At this time, the rod slides on the valve cover 310 away from the rotating connection of the valve cover 310 and tends the cover plate 10 to rotate towards the injection tube 20. This switches the one-way valve 30 from the open state to the closed state.

[0044] like Figure 4 As shown, in some embodiments, the top cover assembly further includes a formation pin 40. The formation pin 40 is detachably mounted to the injection port 110. A channel 410 is formed within the formation pin 40. The formation pin 40 is configured to open the one-way valve 30 and communicate with the inside and outside of the cover plate 10 through the channel 410.

[0045] It is understandable that after electrolyte injection, the individual battery cells need to be left to stand for a period of time to complete formation. Formation ensures the consistency of individual battery cells, improves their performance, and eliminates potential hazards, thereby enhancing their safety. During the formation stage, formation pins 40 need to be inserted into the electrolyte injection hole 110. However, formation gas is generated during the formation stage. In this embodiment, the formation pins 40 can open the one-way valve 30 and, through their internal channels 410, connect the internal space of the individual battery cell with the external environment, thereby promptly releasing the formation gas and preventing its accumulation inside the individual battery cell, which could cause defects such as bulging.

[0046] It should be noted that when the formation pin 40 is pulled out, the valve cover 310 of the one-way valve 30 will rotate towards the injection tube 20, so that the one-way valve 30 switches from the open state to the closed state. The passage 410 connecting the inside and outside of the cover plate 10 means that when the formation pin 40 is inserted into the injection hole 110, the passage 410 can conduct the internal space of the single cell to the external environment space.

[0047] In related technologies, the electrolyte injection process for a single battery cell is typically as follows: primary electrolyte injection - insertion of formation pin 40 - standing - removal of formation pin 40 - formation - insertion of formation pin 40 - standing - removal of formation pin 40 - secondary electrolyte injection - welding to seal the electrolyte injection hole 110. It is evident that the above process requires repeated insertion and removal of the formation pin 40, making its use relatively frequent. In this embodiment, based on the cooperation between the one-way valve 30 and the formation pin 40, the electrolyte injection process can be simplified to: primary electrolyte injection - standing - insertion of formation pin 40 - formation - removal of formation pin 40 - standing - secondary electrolyte injection - welding to seal the electrolyte injection hole 110. Alternatively, the electrolyte injection process can be simplified to: electrolyte injection - standing - insertion of formation pin 40 - formation - removal of formation pin 40 - standing - welding to seal the electrolyte injection hole 110. Alternatively, the electrolyte injection process can be simplified to: electrolyte injection - standing - insertion of formation pin 40 - formation - removal of formation pin 40 - standing. This process eliminates the need to seal the injection hole 110 via welding, facilitating electrolyte replenishment after a period of battery use. Therefore, in this embodiment, the cooperation between the one-way valve 30 and the formation pin 40 optimizes the electrolyte injection process, reduces the use of the formation pin 40, and allows for electrolyte replenishment at any time during battery use.

[0048] Please continue reading. Figure 4 In some embodiments, the aperture of channel 410 is D, which satisfies: 0.5 mm ≤ D ≤ 3 mm.

[0049] Understandably, if the aperture of channel 410 is less than 0.5 mm, the formation gas will have difficulty escaping from the channel 410 into the individual cell, causing the formation gas to accumulate inside the individual cell and resulting in defects such as casing bulging. Since the aperture of injection hole 110 and / or injection tube 20 is usually only 4 mm, if the aperture of channel 410 is greater than 3 mm, the solid part of formation nail 40 will be less, resulting in insufficient strength of formation nail 40 and failing to meet the usage requirements.

[0050] For example, the aperture of channel 410 can be set to 0.5 mm, 1 mm, 2 mm, 3 mm, or any value between the two.

[0051] Please continue reading. Figure 4 In some embodiments, the length of the chemically formed nail 40 is L1, and the sum of the depths of the injection hole 110 and the injection tube 20 is L2, satisfying: L1 > L2.

[0052] Understandably, the length L1 of the formation pin 40 is greater than the sum of the depths L2 of the injection hole 110 and the injection tube 20. This ensures that after the formation pin 40 is inserted into the injection tube 20 through the injection hole 110, it can push the valve cover 310 away from the injection tube 20, thus ensuring that the one-way valve 30 can switch from the closed state to the open state after the formation pin 40 is inserted. This allows the channel 410 to connect the internal space of the individual battery cell with the external environment, allowing the formation gas to be discharged from the channel 410.

[0053] In some embodiments, the following condition is satisfied: 1 mm ≤ L1 - L2 ≤ 7 mm.

[0054] Understandably, if the difference between the length L1 of the formation pin 40 and the sum L2 of the depths of the injection hole 110 and the injection tube 20 is less than 1 mm, the valve cover 310 may be in a partially open state after the formation pin 40 is inserted into the injection hole 110 and the injection tube 20. In this case, the valve cover 310 may abut against the lower end of the formation pin 40 and close the channel 410, preventing the channel 410 from connecting the internal space of the individual cell with the external environment. If the difference between the length L1 of the formation pin 40 and the sum L2 of the depths of the injection hole 110 and the injection tube 20 is greater than 7 mm, the formation pin 40 may abut against or insert into the electrode assembly, causing damage to the electrode assembly and resulting in defects and safety hazards in the individual cell.

[0055] For example, the difference between the length L1 of the chemically formed nail 40 and the sum L2 of the depths of the injection hole 110 and the injection tube 20 is set to 1 mm, 3 mm, 5 mm, 7 mm, or any value between the two.

[0056] Please continue reading. Figure 4 In some embodiments, the chemically formed nail 40 includes a first segment 420 and a second segment 430. The outer diameter of the first segment 420 is less than or equal to the diameter of the injection hole 110, and the outer diameter of the first segment 420 is less than or equal to the diameter of the injection tube 20. The outer diameter of the second segment 430 is greater than the diameter of the injection hole 110. The first segment 420 is configured to pass through the injection hole 110 into the injection tube 20 and open the one-way valve 30.

[0057] Understandably, since the outer diameter of the first segment 420 is less than or equal to the diameter of the injection hole 110, and the outer diameter of the first segment 420 is less than or equal to the diameter of the injection tube 20, the first segment 420, as the part inserted into the injection hole 110 and the injection tube 20, will switch the one-way valve 30 from the closed state to the open state after the first segment 420 pushes the valve cover 310 away from the injection tube 20. The outer diameter of the second segment 430 is greater than the diameter of the injection hole 110, so the second segment 430 cannot be inserted into the injection hole 110, thus acting as a limiter to prevent the formation pin 40 from being fully inserted into the injection hole 110. Furthermore, since the second segment 430 is located outside the injection hole 110, it can be clamped to facilitate the removal of the formation pin 40.

[0058] In some embodiments, the channel 410 extends axially along the first segment 420 and the second segment 430, and passes through both the first segment 420 and the second segment 430.

[0059] To facilitate the insertion of the first segment 420 into the injection hole 110 and the injection tube 20, it is preferable that the outer diameter of the first segment 420 is smaller than the diameter of the injection hole 110 and the outer diameter of the first segment 420 is smaller than the diameter of the injection tube 20.

[0060] It should be noted that, in order to ensure that the first section 420 can open the one-way valve 30, the length of the first section 420 is greater than the sum of the depths of the injection hole 110 and the injection tube 20.

[0061] Please continue reading. Figure 4 In some embodiments, the second segment 430 has an expanding sub-segment 4310 with an increasing outer diameter along the direction away from the cover plate 10.

[0062] Understandably, the design of the expanding sub-segment 4310 facilitates the clamping mechanism's gripping of the second segment 430 and the removal of the forming pin 40 from the injection hole 110. Specifically, when the clamping mechanism grips the second segment 430, the distance between the two jaws of the clamping mechanism is fixed. Because the second segment 430 has the expanding sub-segment 4310, the two jaws cannot slide relative to the second segment 430 in a direction away from the cover plate 10, ensuring reliable gripping of the second segment 430 by the clamping mechanism and facilitating the removal of the forming pin 40.

[0063] This application also provides a single battery cell. The single battery cell includes the top cover assembly as described in the foregoing embodiments.

[0064] In this embodiment, by installing a one-way valve 30 on the injection tube 20, when electrolyte is injected into the individual battery cell through the injection hole 110 and the injection tube 20, the one-way valve 30 is in the open state, allowing the electrolyte to flow into the individual battery cell. After the injection is completed and the injection needle is removed, the one-way valve 30 closes the injection tube 20. This prevents the electrolyte inside the individual battery cell from leaking or spraying out from the injection tube 20 and the injection hole 110, avoiding electrolyte waste and preventing electrolyte leakage from affecting the production environment and endangering employee health.

[0065] This application also provides a battery pack. The battery pack includes individual battery cells as described in the foregoing embodiments.

[0066] In this embodiment, by installing a one-way valve 30 on the injection tube 20, when electrolyte is injected into the individual battery cell through the injection hole 110 and the injection tube 20, the one-way valve 30 is in the open state, allowing the electrolyte to flow into the individual battery cell. After the injection is completed and the injection needle is removed, the one-way valve 30 closes the injection tube 20. This prevents the electrolyte inside the individual battery cell from leaking or spraying out from the injection tube 20 and the injection hole 110, avoiding electrolyte waste and preventing electrolyte leakage from affecting the production environment and endangering employee health.

[0067] The embodiments of this utility model have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of this utility model. The description of the above embodiments is only for the purpose of helping to understand the method and core ideas of this utility model. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this utility model. Therefore, the content of this specification should not be construed as a limitation of this utility model.

Claims

1. A top cover assembly, characterized in that, include: The cover plate is equipped with an injection hole; The injection tube is connected to the inside of the cover plate, and the injection tube is in communication with the injection hole; A one-way valve, connected to the injection tube, is configured to allow liquid to flow in the direction from the injection port to the injection tube; The one-way valve includes: A valve cover is rotatably connected to the end of the injection tube furthest from the cover plate; A support member, connected to the valve cover, is configured to apply a force to the valve cover so that the valve cover closes the injection tube under the action of the force.

2. The top cover assembly according to claim 1, characterized in that, The top cover assembly also includes: A chemically formed pin is detachably installed in the injection hole. A channel is formed inside the chemically formed pin. The chemically formed pin is configured to open the one-way valve and connect the inside and outside of the cover plate through the channel.

3. The top cover assembly according to claim 2, characterized in that, The aperture of the channel is D, which satisfies the following condition: 0.5 mm ≤ D ≤ 3 mm.

4. The top cover assembly according to claim 2, characterized in that, The length of the chemically formed nail is L1, and the sum of the depths of the injection hole and the injection tube is L2, satisfying: L1 > L2.

5. The top cover assembly according to claim 4, characterized in that, The following condition must be met: 1 mm ≤ L1 - L2 ≤ 7 mm.

6. The top cover assembly according to claim 2, characterized in that, The chemically formed nail includes a first segment and a second segment. The outer diameter of the first segment is less than or equal to the diameter of the injection hole and the outer diameter of the first segment is less than or equal to the diameter of the injection tube. The outer diameter of the second segment is greater than the diameter of the injection hole. The first segment is configured to pass through the injection hole into the injection tube and open the one-way valve.

7. The top cover assembly according to claim 6, characterized in that, Along the direction away from the cover plate, the second segment has a gradually expanding sub-segment with an increasing outer diameter.

8. A single battery cell, characterized in that, Includes the top cover assembly as described in any one of claims 1 to 7.

9. A battery pack, characterized in that, Including the single-cell battery as described in claim 8.

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