Double-valve cover plate structure and battery cell

Abstract

The invention relates to the technical field of energy storage equipment, in particular to a double-valve cover plate structure and a battery cell, the double-valve cover plate structure comprises a cover plate and an anti-explosion sheet, the cover plate is provided with a liquid injection hole and a first anti-explosion nick, and the cover plate is made of steel. A second anti-explosion nick is formed in the anti-explosion piece, the anti-explosion piece is annularly welded to the portion, around the liquid injection hole, of the cover plate to form a welding ring, the projection, in the axial direction of the cover plate, of the second anti-explosion nick is located in the welding ring, the anti-explosion piece is made of aluminum, and the preset opening pressure of the second anti-explosion nick is smaller than that of the first anti-explosion nick. The battery cell comprises a steel shell and the double-valve cover plate structure, and the cover plate is connected to the opening of the steel shell in a sealing manner to form a shell of the battery cell. According to the double-valve cover plate structure and the battery cell, the overall structural strength of the battery cell can be ensured, the anti-explosion precision of the anti-explosion valve can be improved, and the safety of the battery cell is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of energy storage equipment, and in particular to a double-valve cover plate structure and a battery core. Background Art

[0002] Existing large cylindrical batteries usually use a steel shell with an open bottom. The coiled pole group is arranged in the shell and is welded and encapsulated with the open end of the shell through the bottom cover. A notch is set on the bottom cover to act as an explosion-proof valve. By controlling the residual thickness of the notch, it can be ensured that the explosion-proof valve opens normally under the set air pressure to meet the explosion-proof needs when the battery cell is out of control, prevent the battery from deforming and causing the shell to burst or the battery cell to explode, and ensure the safety of the battery cell. However, the steel shell notch explosion-proof valve will be affected by processing errors and production fluctuations. The actual opening pressure of the notch and the set pressure have a large deviation range. In extreme cases, there is still a risk of shell bursting or battery cell explosion. The aluminum notch explosion-proof valve has high opening accuracy, but the cover is made of aluminum material, which is not conducive to the structural strength of the cover on the one hand, and the structural strength of the welding point between the cover and the steel shell on the other hand, resulting in low overall structural strength of the battery cell. Summary of the invention

[0003] One object of the present invention is to provide a double-valve cover plate structure, which can ensure the overall structural strength of the battery cell, improve the explosion-proof accuracy of the explosion-proof valve, and improve the safety of the battery cell.

[0004] To achieve this object, the present invention adopts the following technical solutions:

[0005] A double valve cover plate structure is provided, comprising:

[0006] A cover plate, wherein a liquid injection hole and a first explosion-proof notch are formed on the cover plate, and the material of the cover plate is steel;

[0007] An explosion-proof piece, wherein a second explosion-proof notch is formed on the explosion-proof piece, and the explosion-proof piece is annularly welded to the cover plate around the injection hole to form a welding ring, and the projection of the second explosion-proof notch along the axial direction of the cover plate is located within the welding ring, the material of the explosion-proof piece is aluminum, and the preset opening pressure of the second explosion-proof notch is less than the preset opening pressure of the first explosion-proof notch.

[0008] Optionally, a first annular groove is formed on a side of the cover plate facing away from the inner cavity of the battery cell, and the first explosion-proof notch is formed at the bottom of the first annular groove.

[0009] Optionally, a liquid injection groove is formed on a side of the cover plate facing away from the inner cavity of the battery cell, and the liquid injection hole is located at the bottom of the liquid injection groove.

[0010] Optionally, the explosion-proof plate is welded to the bottom of the liquid injection groove.

[0011] Optionally, a protective sheet is further included, wherein the injection groove is located in the area enclosed by the first annular groove, the protective sheet is located on the side of the cover plate away from the inner cavity of the battery cell, and the protective sheet is annularly connected to the first outer end surface of the first annular groove.

[0012] Optionally, the protection sheet is also connected to the annular end surface between the liquid injection groove and the first annular groove.

[0013] Optionally, a second annular groove is formed on the side of the cover plate facing away from the inner cavity of the battery cell, the first annular groove is located in the area surrounded by the second annular groove, and the end surface of the protective sheet facing away from the inner cavity of the battery cell is flush with the second outer end surface of the second annular groove.

[0014] Optionally, the protective sheet is bonded to the cover plate.

[0015] Optionally, the thickness of the explosion-proof plate where the second explosion-proof notch is not formed is less than or equal to 0.5 mm.

[0016] Another object of the present invention is to provide a battery cell that can ensure the overall structural strength of the battery cell, improve the explosion-proof accuracy of the explosion-proof valve, and improve the safety of the battery cell.

[0017] To achieve this object, the present invention adopts the following technical solutions:

[0018] Provided is a battery core, comprising a steel shell and the above-mentioned double-valve cover plate structure, wherein the cover plate is sealed and connected to the opening of the steel shell to form an outer shell of the battery core.

[0019] Beneficial effects of the present invention:

[0020] The present invention provides a double-valve cover plate structure, including a cover plate and an explosion-proof disc, wherein a liquid injection hole and a first explosion-proof notch are provided on the cover plate, and the material of the cover plate is steel. A second explosion-proof notch is provided on the explosion-proof disc, and the explosion-proof disc is annularly welded to the cover plate around the liquid injection hole to form a welding ring, and the projection of the second explosion-proof notch along the axial direction of the cover plate is located within the welding ring, and the material of the explosion-proof disc is aluminum, and the preset opening pressure of the second explosion-proof notch is less than the preset opening pressure of the first explosion-proof notch. The second explosion-proof notch can be used as a primary explosion-proof, and since the material of the explosion-proof disc is aluminum, the accuracy of the opening pressure of the primary explosion-proof can be improved, ensuring that there is no danger of shell explosion or battery cell explosion, thereby ensuring the safety of the battery cell. The aperture of the liquid injection hole is small, and the pressure release is slow. The first explosion-proof notch can be used as a secondary explosion-proof to accelerate gas discharge. The accuracy requirement for the secondary explosion-proof is low, so the first explosion-proof notch is suitable for being set at the steel cover plate. The double-valve cover plate structure can ensure that the cover plate is still made of steel, thereby ensuring the structural strength of the cover plate itself and the structural strength of the welding point between the cover plate and the steel shell, thereby ensuring the overall structural strength of the battery cell.

[0021] The present invention also provides a battery cell, comprising a steel shell and the above-mentioned double valve cover plate structure, wherein the cover plate is sealed and connected to the opening of the steel shell to form the outer shell of the battery cell. The battery cell can ensure the overall structural strength of the battery cell, and can also improve the explosion-proof accuracy of the explosion-proof valve and improve the safety of the battery cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 is a schematic structural diagram of a battery cell provided by an embodiment of the present invention from a first perspective;

[0023] Figure 2 is a structural schematic diagram of a battery cell provided by an embodiment of the present invention from a second viewing angle;

[0024] Figure 3 is an exploded schematic diagram of a battery cell provided by an embodiment of the present invention;

[0025] Figure 4 is a schematic structural diagram of a battery cell provided by an embodiment of the present invention from a third viewing angle;

[0026] Figure 5 yes Figure 4 Partial view of the AA section view.

[0027] In the figure:

[0028] 1. Cover plate; 11. First annular groove; 111. First explosion-proof notch; 12. Liquid injection groove; 121. Liquid injection hole; 13. First peripheral end surface; 14. Annular end surface; 15. Second annular groove; 16. Second peripheral end surface;

[0029] 2. Explosion-proof plate; 3. Protective plate;

[0030] 100. Double valve cover plate structure; 200. Steel shell. DETAILED DESCRIPTION

[0031] The technical solution of the present invention is further described below in conjunction with the accompanying drawings and implementation methods. It is to be understood that the specific embodiments described herein are only used to explain the present invention, rather than to limit the present invention. It should also be noted that, for ease of description, only the parts related to the present invention are shown in the accompanying drawings, rather than all of them.

[0032] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection or a detachable connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, and it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0033] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0034] Existing large cylindrical batteries usually use a steel shell with an open bottom. The coiled pole group is arranged in the shell and is welded and encapsulated with the open end of the shell through the bottom cover. A notch is set on the bottom cover to act as an explosion-proof valve. By controlling the residual thickness of the notch, it can be ensured that the explosion-proof valve opens normally under the set air pressure to meet the explosion-proof needs when the battery cell is out of control, prevent the battery from deforming and causing the shell to burst or the battery cell to explode, and ensure the safety of the battery cell. However, the steel shell notch explosion-proof valve will be affected by processing errors and production fluctuations. The actual opening pressure of the notch and the set pressure have a large deviation range. In extreme cases, there is still a risk of shell bursting or battery cell explosion. The aluminum notch explosion-proof valve has high opening accuracy, but the cover is made of aluminum material, which is not conducive to the structural strength of the cover on the one hand, and the structural strength of the welding point between the cover and the steel shell on the other hand, resulting in low overall structural strength of the battery cell.

[0035] In order to solve the above problems, the present embodiment provides a double-valve cover plate structure 100, which can ensure the overall structural strength of the battery cell, improve the explosion-proof accuracy of the explosion-proof valve, and improve the safety of the battery cell.

[0036] like Figure 1-Figure 5 As shown, the double valve cover plate structure 100 of this embodiment includes a cover plate 1 and an explosion-proof disc 2. The cover plate 1 is provided with a liquid injection hole 121 and a first explosion-proof notch 111. The cover plate 1 is made of steel. The explosion-proof disc 2 is provided with a second explosion-proof notch (not shown in the figure). The explosion-proof disc 2 is annularly welded to the cover plate 1 around the liquid injection hole 121 to form a welding ring, and the projection of the second explosion-proof notch along the axial direction of the cover plate 1 is located in the welding ring. The material of the explosion-proof disc 2 is aluminum, and the preset opening pressure of the second explosion-proof notch is less than the preset opening pressure of the first explosion-proof notch 111. It should be noted that the projection of the second explosion-proof notch along the axial direction of the cover plate 1 is located in the welding ring, which does not mean that it is located in the welding area of ​​the welding ring, but means that it is located in the middle space surrounded by the welding ring to ensure that welding does not affect the second explosion-proof notch.

[0037] The second explosion-proof notch can be used as the first-level explosion-proof, and because the material of the explosion-proof plate 2 is aluminum, the accuracy of the opening pressure of the first-level explosion-proof can be improved to ensure that there is no danger of shell explosion or battery cell explosion, thereby ensuring the safety of the battery cell. The aperture of the injection hole 121 is small, and the pressure release is slow. The first explosion-proof notch 111 can be used as the second-level explosion-proof, accelerating the gas discharge, further improving safety, and the precision requirement for the second-level explosion-proof is low, so the first explosion-proof notch 111 is suitable for being set at the steel cover plate 1. The double-valve cover plate structure 100 can ensure that the cover plate 1 is still made of steel while ensuring the completeness of the explosion-proof, thereby ensuring the structural strength of the cover plate 1 itself and the structural strength of the welding point between the cover plate 1 and the steel shell 200, thereby ensuring the overall structural strength of the battery cell.

[0038] Optionally, the first explosion-proof notch 111 is an open annular notch, and the ratio of the circumference of the first explosion-proof notch 111 to the circumference of the circle to which it corresponds is less than 0.95 to ensure its explosion-proof performance.

[0039] Optionally, the second explosion-proof notch is a cross or a straight line, so as to facilitate processing on a smaller explosion-proof disc 2. Optionally, the second explosion-proof notch is arranged on any side end face of the explosion-proof disc 2, as long as it is located within the welding ring. In this embodiment, the second explosion-proof notch is arranged on the end face of the explosion-proof disc 2 away from the inner cavity of the battery cell.

[0040] Optionally, a first annular groove 11 is provided on the side of the cover plate 1 facing away from the inner cavity of the battery cell, and a first explosion-proof notch 111 is provided at the bottom of the first annular groove 11, so as to avoid the first annular groove 11 being located on the end face of the cover plate 1, thereby preventing it from being damaged by bumps and ensuring that the actual opening pressure does not deviate from the preset pressure range.

[0041] Optionally, a liquid injection groove 12 is provided on the side of the cover plate 1 away from the inner cavity of the battery cell, and the liquid injection hole 121 is located at the bottom of the liquid injection groove 12. The liquid injection groove 12 is provided to facilitate the liquid injection operation. Optionally, the side wall of the liquid injection groove 12 is inclined to guide the liquid injection operation. Optionally, the liquid injection groove 12 is located at the center of the cover plate 1, and the liquid injection hole 121 is coaxially arranged with the cover plate 1.

[0042] Optionally, the explosion-proof disc 2 is welded to the bottom of the injection groove 12, so as to protect the explosion-proof disc 2 and prevent the explosion-proof disc 2 from being subjected to force. Optionally, the end face of the explosion-proof disc 2 facing away from the inner cavity of the battery cell is lower than the height of the side wall of the injection groove 12. This arrangement can protect the second explosion-proof notch from being damaged by bumps, ensure that the actual opening pressure does not deviate from the preset pressure range, and ensure that the first-level explosion-proof has high precision. On the other hand, it can also prevent the explosion-proof disc 2 from being subjected to force, causing the connection between the explosion-proof disc 2 and the cover plate 1 to loosen, causing problems such as electrolyte leakage.

[0043] Optionally, the thickness of the explosion-proof plate 2 where the second explosion-proof notch is not provided is less than or equal to 0.5 mm. When the thickness of the explosion-proof plate 2 is greater than 0.5 mm, the welding quality between the aluminum explosion-proof plate 2 and the bottom of the steel injection groove 12 will be unstable, which is not conducive to the quality stability of the battery. Taking the 4680 large cylindrical battery cell as an example, since the cylindrical shell has a good tolerance for gas production, when the positive electrode uses materials such as 9 series high nickel, the nickel content is high and the activity is high, it is easy to react with the electrolyte. And because the pole group occupies a large proportion in the shell, the electrolyte that can be accommodated in the shell is relatively small, and the electrolyte is prone to dryness in the later stage of the cycle, resulting in a reduction or termination of the cycle life, so it is necessary to perform secondary injection. When the thickness of the explosion-proof plate 2 is greater than 0.5 mm, the difficulty of disassembling the explosion-proof plate 2 increases, which is not conducive to the secondary injection operation of the battery cell.

[0044] In order to further protect the first explosion-proof notch 111 and the second explosion-proof notch, and prevent corrosion leakage or sudden change of opening pressure at the notch due to the small thickness of the remaining material at the notch in some harsh environments, the double-valve cover plate structure 100 optionally further includes a protective sheet 3, the injection groove 12 is located in the area surrounded by the first annular groove 11, the protective sheet 3 is located on the side of the cover plate 1 away from the inner cavity of the battery cell, and the protective sheet 3 is annularly connected to the first outer peripheral end surface 13 of the first annular groove 11. That is, the protective sheet 3 covers the injection groove 12 and the first annular groove 11, and can protect the first explosion-proof notch 111 and the second explosion-proof notch.

[0045] Optionally, the protective sheet 3 is also connected to the annular end face 14 between the injection groove 12 and the first annular groove 11, that is, the protective sheet 3 can be further supported by the annular end face 14 to prevent it from being concave and deformed, and increasing the connection area is beneficial to increasing the connection strength between the protective sheet 3 and the cover plate 1 to prevent the protective sheet 3 from shifting.

[0046] Optionally, a second annular groove 15 is further provided on the side of the cover plate 1 away from the inner cavity of the battery cell, the first annular groove 11 is located in the area surrounded by the second annular groove 15, and the end surface of the protective sheet 3 away from the inner cavity of the battery cell is flush with the second peripheral end surface 16 of the second annular groove 15. Optionally, in this embodiment, the second peripheral end surface 16 is located at the edge of the side of the cover plate 1 away from the inner cavity of the battery cell, and the protective sheet 3 is flush with the edge of the cover plate 1, which can ensure that the battery cell is placed stably and is conducive to aesthetics.

[0047] Optionally, the protection sheet 3 is bonded to the cover plate 1 to facilitate removal of the protection sheet 3 during secondary liquid injection.

[0048] Optionally, the material of the protective sheet 3 is plastic to reduce weight. Optionally, the protective sheet 3 is made of transparent material, which makes it easy to observe whether the explosion-proof sheet 2 has leakage due to poor welding or abnormal welding, and can also provide protection for the first explosion-proof notch 111 to prevent corrosion at the first explosion-proof notch 111 and / or the second explosion-proof notch due to long-term use in harsh environments.

[0049] When the battery cell needs to be replenished, it is only necessary to remove the protective sheet 3 first, and then remove the welded explosion-proof sheet 2 to replenish the electrolyte. After the replenishment is completed, a new explosion-proof sheet 2 can be re-welded. In order to ensure the sealing, the welding residue of the explosion-proof sheet 2 needs to be polished. This is a conventional design and will not be described in detail here.

[0050] The double valve cover plate structure 100 has a two-stage explosion-proof design. The first-stage explosion-proof pressure is accurate and stable to open. When the pressure is too high, the second-stage explosion-proof opening can quickly release the gas inside the thermal runaway battery cell, reduce the internal pressure, and make the safety of the battery cell more guaranteed. In addition, the double valve cover plate structure 100 adopts two layers of protection, not only by welding the explosion-proof plate 2 to block the injection hole 121, but also by the protective plate 3 to further prevent leakage, which can improve the safety of the battery cell and the service life of the battery cell. Not only that, the double valve cover plate structure 100 also has the function of secondary filling of electrolyte, which can further extend the life of the battery cell and make the cascade utilization of the battery cell possible. In addition, the double valve cover plate structure 100 also has a performance repair function, that is, according to the battery cell situation, the old electrolyte can be replaced at any time to extend the cycle life of the battery cell, while reducing the frequency of replacement of waste batteries, reducing resource waste, and saving energy and reducing emissions.

[0051] This embodiment also provides a battery cell, including a steel shell 200 and the above-mentioned double valve cover plate structure 100, and the cover plate 1 is sealed and connected to the opening of the steel shell 200 to form the outer shell of the battery cell. Optionally, the cover plate 1 and the steel shell 200 are laser welded and packaged. In this embodiment, the battery cell is a large cylindrical battery cell, and of course the double valve cover plate structure 100 can also be applied to a rectangular battery cell. The battery cell can ensure the overall structural strength of the battery cell, and can also improve the explosion-proof accuracy of the explosion-proof valve and improve the safety of the battery cell.

[0052] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the embodiments here. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. Double valve cover plate structure, characterized in that: include: A cover plate (1), wherein the cover plate (1) is provided with a liquid injection hole (121) and a first explosion-proof notch (111), and the material of the cover plate (1) is steel; An explosion-proof plate (2), wherein a second explosion-proof notch is formed on the explosion-proof plate (2), the explosion-proof plate (2) is annularly welded to the cover plate (1) around the injection hole (121) to form a welding ring, and the projection of the second explosion-proof notch along the axial direction of the cover plate (1) is located within the welding ring, the material of the explosion-proof plate (2) is aluminum, and the preset opening pressure of the second explosion-proof notch is less than the preset opening pressure of the first explosion-proof notch (111).

2. The double valve cover plate structure according to claim 1, characterized in that: A first annular groove (11) is provided on the side of the cover plate (1) facing away from the inner cavity of the battery cell, and the first explosion-proof notch (111) is provided at the bottom of the first annular groove (11).

3. The double valve cover plate structure according to claim 2, characterized in that: A liquid injection groove (12) is provided on the side of the cover plate (1) facing away from the inner cavity of the battery cell, and the liquid injection hole (121) is located at the bottom of the liquid injection groove (12).

4. The double valve cover plate structure according to claim 3, characterized in that: The explosion-proof disc (2) is welded to the bottom of the liquid injection groove (12).

5. The double valve cover plate structure according to claim 3, characterized in that: It also comprises a protective sheet (3), the injection groove (12) is located in the area enclosed by the first annular groove (11), the protective sheet (3) is located on the side of the cover plate (1) away from the inner cavity of the battery cell, and the protective sheet (3) is annularly connected to the first outer end surface (13) of the first annular groove (11).

6. The double valve cover plate structure according to claim 5, characterized in that: The protection sheet (3) is also connected to the annular end surface (14) between the liquid injection groove (12) and the first annular groove (11).

7. The double valve cover plate structure according to claim 5, characterized in that: A second annular groove (15) is also provided on the side of the cover plate (1) facing away from the inner cavity of the battery cell; the first annular groove (11) is located in the area enclosed by the second annular groove (15); and the end surface of the protective sheet (3) facing away from the inner cavity of the battery cell is flush with a second outer end surface (16) of the second annular groove (15).

8. The double valve cover plate structure according to claim 5, characterized in that: The protective sheet (3) is bonded to the cover plate (1).

9. The double valve cover plate structure according to any one of claims 1 to 8, characterized in that: The thickness of the explosion-proof plate (2) where the second explosion-proof notch is not formed is less than or equal to 0.5 mm.

10. A battery cell, characterized in that: It comprises a steel shell (200) and a double-valve cover plate structure as claimed in any one of claims 1 to 9, wherein the cover plate (1) is sealed and connected to the opening of the steel shell (200) to form the outer shell of the battery cell.

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