Cap assembly and battery cell

Abstract

The utility model relates to the technical field of batteries, and discloses a cap assembly and a battery cell. The cap assembly comprises a top cover and an anti-explosion valve located below the top cover, the anti-explosion valve comprises an anti-explosion valve body and an annular flange located on the peripheral side of the anti-explosion valve body, the free end of the annular flange is bent towards the upper surface of the top cover to form a bent part, and the bent part, the top cover and the anti-explosion valve body are welded to form a whole. And annular welding areas are respectively formed at the joints of the top cover and the bending part as well as the explosion-proof valve body. According to the explosion-proof valve, the overlapping area of the bending part, the top cover and the explosion-proof valve body is welded, so that the welding penetration risk can be reduced, and the reliability of the welding structure is improved.

Description

Technical Field

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

[0002] The cap assembly is a key component in small cylindrical batteries, used for electrical connection, safety, sealing, and structural support. It typically consists of several parts, including a cap plate, an explosion-proof valve, and seals. Since both the cap plate and the explosion-proof valve are made of metal, laser penetration welding is usually used to join them together to form a single unit. However, due to variations in welding skill levels among workers, problems such as weld burn-through can easily occur during the welding process, resulting in a connection between the explosion-proof valve and the cap plate that does not meet the intended requirements. Utility Model Content

[0003] In view of this, the present invention provides a cap assembly and a battery cell to solve the problem of weld burn-through that easily occurs during the welding process of explosion-proof valve and cover plate.

[0004] In a first aspect, the present invention provides a cap assembly, including a top cover and an explosion-proof valve located below the top cover. The explosion-proof valve includes an explosion-proof valve body and an annular flange located around the periphery of the explosion-proof valve body. The free end of the annular flange is bent toward the upper surface of the top cover to form a bent portion. The bent portion, the top cover, and the explosion-proof valve body are welded together to form an integral whole, and the connection between the top cover and the bent portion and the explosion-proof valve body respectively forms an annular welding area.

[0005] Beneficial Effects: This invention reduces the risk of burn-through and improves the reliability of the welded structure by welding the overlapping areas of the bending section, top cover, and explosion-proof valve body. Specifically, the increased material thickness at the weld joint in the overlapping area allows for more even heat distribution during welding, making it easier for operators to control the penetration depth and effectively preventing burn-through due to localized heat concentration. Secondly, compared to laser spot welding, this invention forms annular welding areas at the connections between the top cover and the bending section and the explosion-proof valve body, increasing the welding contact area and resulting in a more secure connection between the top cover and the explosion-proof valve.

[0006] In one alternative embodiment, the edge of the top cover abuts against the inner wall of the annular flange, and the upper surface of the top cover fits against the lower surface of the bent portion.

[0007] Beneficial effects: This invention abuts the edge of the top cover against the inner wall of the annular flange, reducing the gap between the top cover and the annular flange and making the overall structure of the cap assembly more compact. Secondly, this invention fits the upper surface of the top cover against the lower surface of the bent portion, increasing the contact area between them. This not only improves the convenience of welding operations but also facilitates the formation of a larger welding area during welding, enhancing the connection strength between the top cover and the explosion-proof valve and ensuring their overall integrity.

[0008] In one alternative embodiment, the bend of the annular flange is flush with the upper surface of the top cover.

[0009] Beneficial Effects: If the bend of the annular flange is lower than the upper surface of the top cover, the bend will interfere with the edge of the top cover during the forming process, causing damage to the structure of the top cover or the annular flange itself. Conversely, if the bend of the annular flange is higher than the upper surface of the top cover, although the lower surface of the bend can smoothly fit with the upper surface of the top cover without interference, part of the annular flange structure will not be fully utilized and will occupy additional space. Therefore, this invention keeps the bend of the annular flange flush with the upper surface of the top cover, which ensures that the bend is easy to form and also makes the overall structure of the cap assembly after the bend is formed more compact.

[0010] In one optional embodiment, the explosion-proof valve body is provided with a first groove, the area of ​​the top cover corresponding to the first groove protrudes upward to form a protrusion, and the annular welding area is arranged around the protrusion.

[0011] Beneficial Effects: By providing a first groove on the explosion-proof valve body, this invention can improve the structural strength of the valve body to a certain extent, preventing abnormal valve opening during normal use of the battery cell and improving the reliability of the explosion-proof valve. Furthermore, providing a protrusion in the area corresponding to the first groove on the top cover further increases the distance between the first groove and the lower surface of the top cover, providing sufficient deformation space for the explosion-proof valve. Moreover, the annular welding area surrounding the protrusion ensures sufficient welding area between the top cover, the bent portion, and the explosion-proof valve body, making the connection between the top cover and the explosion-proof valve more robust. It also evenly distributes welding stress within the annular area, avoiding weld cracking caused by localized stress concentration.

[0012] In one alternative embodiment, the free end of the bent portion is spaced apart from the protrusion.

[0013] Beneficial effects: This invention sets the free end of the bend and the protrusion at an interval, meaning that a large portion does not need to be reserved in advance on the annular flange for making the bend. This allows the annular flange to be made relatively smaller, saving material and reducing the manufacturing cost of the explosion-proof valve. However, it is understandable that the size of the bend cannot be made too small, otherwise it may affect the welding area between the bend and the top cover, reducing the welding strength between them.

[0014] In one optional embodiment, the bottom of the first groove is provided with an annular groove and a second groove, the annular groove being arranged around the periphery of the opening of the second groove; the cap assembly further includes an orifice plate located below the explosion-proof valve body, the orifice plate being welded to the bottom of the second groove.

[0015] Beneficial effects: The thickness of the annular groove at the bottom of the first groove is less than the thickness of other areas at the bottom of the first groove. Therefore, in the event of thermal runaway of the battery cell, the annular groove will break first due to its thinner thickness, forming a pressure relief channel, thus ensuring the safety of the battery cell. Secondly, by setting a second groove on the bottom of the first groove, the bottom of the second groove can preferentially contact the orifice plate. In this way, while ensuring a stable connection between the explosion-proof valve body and the orifice plate during normal use of the battery cell, the connection between the two can also be disconnected in the event of thermal runaway of the battery cell. This allows the connection between the explosion-proof valve and the electrode group to be disconnected in the event of thermal runaway of the battery cell, cutting off the circuit and preventing electrical sparks caused by circuit continuity during subsequent valve opening, thus reducing the possibility of safety accidents. Furthermore, by placing an annular groove around the periphery of the second groove opening, the second groove can be separated from the explosion-proof valve body due to the breakage of the annular groove during thermal runaway. In this way, even if the orifice plate does not separate from the second groove in time, the explosion-proof valve and the electrode assembly will be disconnected due to the breakage of the annular groove, ensuring the safety and reliability of the pressure relief process.

[0016] In one alternative embodiment, the thickness of the orifice plate is less than the thickness of the explosion-proof valve body.

[0017] Beneficial effects: Compared to the explosion-proof valve body, the orifice plate is closer to the inside of the battery cell. Therefore, by making the orifice plate thinner, it can be made to break or deform first when the battery cell experiences thermal runaway, thus creating favorable conditions for the explosion-proof valve to open and release pressure.

[0018] In one optional embodiment, a first sealing element is provided between the orifice plate and the explosion-proof valve body, the first sealing element having a first through hole, and the connection between the orifice plate and the bottom of the second groove is located within the first through hole.

[0019] Beneficial effects: By providing an insulating component between the orifice plate and the explosion-proof valve body, and by providing a first through hole on the insulating component suitable for the connection between the orifice plate and the bottom of the second groove, the orifice plate and the explosion-proof valve body can be made to contact only at the bottom of the second groove.

[0020] In one optional embodiment, the cap assembly further includes a second seal having a second through hole, the top cover and the explosion-proof valve being disposed within the second through hole, and the outer wall of the annular flange being fitted against the wall of the second through hole.

[0021] Beneficial effects: By incorporating a second sealing element, this invention isolates the top cover and explosion-proof valve from the battery cell housing, preventing short circuits. It also provides reliable sealing protection for the top cover and explosion-proof valve, preventing electrolyte leakage and thus avoiding corrosion of surrounding components and performance degradation due to electrolyte leakage. Furthermore, the outer wall of the annular flange fits snugly against the wall of the second through hole, preventing external dust, moisture, and other impurities from entering the battery cell and reducing the risk of cell malfunction.

[0022] Secondly, this utility model also provides a battery cell, comprising:

[0023] The housing has a cavity and an opening communicating with the cavity;

[0024] An electrode assembly is disposed within the cavity, and an electrode tab is provided at the end of the electrode assembly facing the opening;

[0025] The aforementioned cap assembly covers and seals the opening, the top cover is located on the outside of the housing, and the explosion-proof valve is connected to the electrode lug.

[0026] Beneficial effects: The battery cell of this utility model includes the cap assembly as described above, and has all the beneficial technical effects of the cap assembly, which will not be repeated here. Attached Figure Description

[0027] To more clearly illustrate the specific embodiments of this utility model or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this utility model. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0028] Figure 1 This is a schematic diagram of the structure of a cap assembly according to an embodiment of the present utility model;

[0029] Figure 2 for Figure 1 A top view of the cap assembly shown;

[0030] Figure 3 for Figure 2 The diagram shows a cross-sectional view of the cap assembly from the AA perspective.

[0031] Explanation of reference numerals in the attached figures:

[0032] 1. Top cover; 101. Protrusion; 2. Explosion-proof valve; 201. Explosion-proof valve body; 2011. First groove; 2012. Annular groove; 2013. Second groove; 202. Annular flange; 2021. Bending part; 3. Orifice plate; 4. First seal; 401. First through hole; 5. Second seal; 501. Second through hole. Detailed Implementation

[0033] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.

[0034] To address the problem of weld burn-through that easily occurs during the welding process of explosion-proof valves and cover plates, this utility model provides a cap assembly and a battery cell.

[0035] The following is combined Figures 1 to 3 The following describes embodiments of the present invention.

[0036] According to embodiments of the present invention, such as Figures 1 to 3 As shown, on one hand, a cap assembly is provided, including a top cover 1 and an explosion-proof valve 2 located below the top cover 1. The explosion-proof valve 2 includes an explosion-proof valve body 201 and an annular flange 202 located around the explosion-proof valve body 201. The free end of the annular flange 202 is bent toward the upper surface of the top cover 1 to form a bent portion 2021. The bent portion 2021, the top cover 1, and the explosion-proof valve body 201 are welded together to form an integral whole, and the connection between the top cover 1 and the bent portion 2021 and the explosion-proof valve body 201 respectively forms an annular welding area.

[0037] This embodiment of the invention reduces the risk of burn-through and improves the reliability of the welded structure by welding the overlapping areas of the bending portion 2021, the top cover 1, and the explosion-proof valve body 201. Specifically, because the overlapping area increases the material thickness at the weld, the heat distribution during the welding process is more uniform. Therefore, operators can more easily control the penetration depth during operation, effectively avoiding burn-through caused by local heat concentration. Secondly, compared with laser spot welding, this embodiment of the invention forms annular welding areas at the connection points of the top cover 1 with the bending portion 2021 and the explosion-proof valve body 201, which increases the welding contact area between the top cover 1 and the bending portion 2021 and the explosion-proof valve body 201, making the top cover 1 and the explosion-proof valve 2 more firmly connected together.

[0038] According to one embodiment of the present invention, such as Figure 3 As shown, the edge of the top cover 1 abuts against the inner wall of the annular flange 202, and the upper surface of the top cover 1 fits against the lower surface of the bent portion 2021. In this embodiment, by abutting the edge of the top cover 1 against the inner wall of the annular flange 202, the gap between the top cover 1 and the annular flange 202 is reduced, making the overall structure of the cap assembly more compact. Furthermore, by fitting the upper surface of the top cover 1 against the lower surface of the bent portion 2021, the contact area between the two is increased. This not only improves the convenience of welding operations but also facilitates the formation of a larger welding area during welding, enhancing the connection strength between the top cover 1 and the explosion-proof valve 2 and ensuring their overall integrity.

[0039] Furthermore, in this embodiment, as Figure 3 As shown, the bend of the annular flange 202 is flush with the upper surface of the top cover 1. It is understandable that if the bend of the annular flange 202 is lower than the upper surface of the top cover 1, the bend 2021 will interfere with the edge of the top cover 1 during the forming process, causing damage to the structure of the top cover 1 or the annular flange 202 itself. Conversely, if the bend of the annular flange 202 is higher than the upper surface of the top cover 1, although the lower surface of the bend 2021 can smoothly fit with the upper surface of the top cover 1 without interference, part of the structure of the annular flange 202 will not be fully utilized, and it will also occupy additional space. Therefore, in this embodiment of the invention, the bend of the annular flange 202 is kept flush with the upper surface of the top cover 1, which ensures that the bend 2021 is easy to form while also making the overall structure of the cap assembly after the bend 2021 is formed more compact.

[0040] According to one embodiment of the present invention, such as Figure 3As shown, the explosion-proof valve body 201 has a first groove 2011, and the area of ​​the top cover 1 corresponding to the first groove 2011 protrudes upward to form a protrusion 101. An annular welding area surrounds the protrusion 101. This embodiment of the invention, by providing the first groove 2011 on the explosion-proof valve body 201, can improve the structural strength of the explosion-proof valve body 201 to a certain extent, preventing abnormal valve opening during normal use of the battery cell and improving the reliability of the explosion-proof valve 2. Furthermore, providing the protrusion 101 in the area of ​​the top cover 1 corresponding to the first groove 2011 can further increase the distance between the first groove 2011 and the lower surface of the top cover 1, reserving sufficient deformation space for the explosion-proof valve 2. Furthermore, the annular welding area surrounding the protrusion 101 ensures sufficient welding area between the top cover 1, the bent part 2021, and the explosion-proof valve body 201, making the connection between the top cover 1 and the explosion-proof valve 2 more secure. On the other hand, it allows the welding stress to be evenly distributed within the annular area, avoiding weld cracking caused by localized welding stress concentration.

[0041] According to one embodiment of the present invention, such as Figure 3 As shown, the free end of the bent portion 2021 is spaced apart from the protrusion 101. In this embodiment of the invention, the spaced-apart arrangement of the free end of the bent portion 2021 from the protrusion 101 means that a large portion does not need to be pre-reserved on the annular flange 202 for manufacturing the bent portion 2021. This means the size of the annular flange 202 can be made relatively small, thus saving material and reducing the manufacturing cost of the explosion-proof valve 2. However, it is understandable that the size of the bent portion 2021 cannot be made too small, otherwise it may affect the welding area between the bent portion 2021 and the top cover 1, reducing the welding strength between them.

[0042] According to one embodiment of the present invention, such as Figure 3As shown, the bottom of the first groove 2011 is provided with an annular groove 2012 and a second groove 2013. The annular groove 2012 is arranged around the periphery of the opening of the second groove 2013. The cap assembly also includes an orifice plate 3 located below the explosion-proof valve body 201, and the orifice plate 3 is welded to the bottom of the second groove 2013. The thickness of the area where the annular groove 2012 is located on the bottom of the first groove 2011 is less than the thickness of other areas on the bottom of the first groove 2011. Therefore, once the battery cell experiences thermal runaway, the annular groove 2012 will break first due to its thinner thickness, forming a pressure relief channel, thereby ensuring the safety of the battery cell. Secondly, by providing the second groove 2013 on the bottom of the first groove 2011, the bottom of the second groove 2013 can preferentially contact the orifice plate 3. In this way, while ensuring a stable connection between the explosion-proof valve body 201 and the orifice plate 3 during normal use of the battery cell, the connection between the two can also be made to detach when the battery cell experiences thermal runaway. This allows the connection between the explosion-proof valve 2 and the electrode group to be disconnected in the event of thermal runaway, thus cutting off the circuit and preventing electrical sparks from being generated during subsequent valve opening, reducing the possibility of safety accidents. Furthermore, the annular notch 2012 is arranged around the periphery of the second groove 2013. This allows the second groove 2013 to detach from the explosion-proof valve body 201 due to the breakage of the annular notch 2012 during thermal runaway. In this way, even if the orifice plate 3 does not detach from the second groove 2013 in time, the explosion-proof valve 2 and the electrode group will still be disconnected due to the breakage of the annular notch 2012, ensuring the safety and reliability of the pressure relief process.

[0043] It should be noted that the tabs on the electrode assembly in the battery cell are not directly connected to the explosion-proof valve body 201, but are indirectly connected to the explosion-proof valve body 201 through the orifice plate 3. In other words, after the battery cell is assembled, the tabs on the electrode assembly are directly connected to the orifice plate 3.

[0044] According to one embodiment of this utility model, the thickness of the orifice plate 3 is less than the thickness of the explosion-proof valve body 201. Compared to the explosion-proof valve body 201, the orifice plate 3 is closer to the interior of the battery cell. Therefore, making the orifice plate 3 thinner allows it to crack or deform first when the battery cell experiences thermal runaway, thus creating favorable conditions for the explosion-proof valve 2 to open and release pressure.

[0045] According to one embodiment of the present invention, such as Figure 3As shown, a first sealing element 4 is provided between the orifice plate 3 and the explosion-proof valve body 201. The first sealing element 4 has a first through hole 401, and the connection between the orifice plate 3 and the bottom of the second groove 2013 is located within the first through hole 401. This embodiment of the invention, by providing a first sealing element 4 between the orifice plate 3 and the explosion-proof valve body 201, and by providing a first through hole 401 on the first sealing element 4 suitable for the connection between the orifice plate 3 and the bottom of the second groove 2013 to pass through, enables the orifice plate 3 and the explosion-proof valve body 201 to contact only at the bottom of the second groove 2013.

[0046] It should be noted that the first sealing element 4 in this embodiment can be, but is not limited to, a plastic sealing ring. It is understood that, since the plastic sealing ring is made of plastic, it can also serve an insulating function.

[0047] According to one embodiment of the present invention, such as Figure 3 As shown, the cap assembly also includes a second sealing element 5, which has a second through hole 501. The top cover 1 and the explosion-proof valve 2 are disposed within the second through hole 501, and the outer wall of the annular flange 202 is in contact with the hole wall of the second through hole 501. By providing the second sealing element 5, this embodiment of the invention can, on the one hand, isolate the top cover 1 and the explosion-proof valve 2 from the battery cell housing, preventing short circuits; on the other hand, it provides reliable sealing protection for the top cover 1 and the explosion-proof valve 2, preventing electrolyte leakage from the battery cell and avoiding corrosion of surrounding components and impact on battery cell performance due to electrolyte leakage. Furthermore, the contact between the outer wall of the annular flange 202 and the hole wall of the second through hole 501 can prevent external dust, moisture, and other impurities from entering the battery cell, reducing the risk of battery cell failure.

[0048] It should be noted that the second sealing element 5 in this embodiment can be, but is not limited to, a plastic sealing ring.

[0049] According to an embodiment of the present invention, another aspect provides a battery cell, comprising: a housing, an electrode assembly, and the aforementioned cap assembly. Specifically, the housing has a cavity and an opening communicating with the cavity; the electrode assembly is disposed within the cavity, and an electrode tab is provided at one end of the electrode assembly facing the opening; the aforementioned cap assembly covers and seals the opening, a top cover 1 is located on the outside of the housing, and an explosion-proof valve 2 is connected to the electrode tab.

[0050] It is understood that the battery cell in this embodiment includes the cap assembly as described above, and has all the beneficial technical effects of the cap assembly, which will not be repeated here.

[0051] It should be noted that the battery cell in this embodiment can be a small cylindrical battery.

[0052] Although embodiments of the present invention have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the present invention, and such modifications and variations all fall within the scope defined by the appended claims.

Claims

1. A cap assembly, characterized in that, The device includes a top cover and an explosion-proof valve located below the top cover. The explosion-proof valve includes an explosion-proof valve body and an annular flange located around the periphery of the explosion-proof valve body. The free end of the annular flange is bent toward the upper surface of the top cover to form a bent portion. The bent portion, the top cover, and the explosion-proof valve body are welded together to form an integral whole. The connection between the top cover and the bent portion and the explosion-proof valve body respectively forms an annular welding area.

2. The cap assembly according to claim 1, characterized in that, The edge of the top cover abuts against the inner wall of the annular flange, and the upper surface of the top cover fits against the lower surface of the bent portion.

3. The cap assembly according to claim 2, characterized in that, The bend of the annular flange is flush with the upper surface of the top cover.

4. The cap assembly according to claim 1, characterized in that, The explosion-proof valve body is provided with a first groove, and the area of ​​the top cover corresponding to the first groove protrudes upward to form a protrusion, and the annular welding area is arranged around the protrusion.

5. The cap assembly according to claim 4, characterized in that, The free end of the bent portion is spaced apart from the protrusion.

6. The cap assembly according to claim 4, characterized in that, The bottom of the first groove is provided with an annular groove and a second groove, the annular groove being arranged around the periphery of the opening of the second groove; the cap assembly also includes an orifice plate located below the explosion-proof valve body, the orifice plate being welded to the bottom of the second groove.

7. The cap assembly according to claim 6, characterized in that, The thickness of the orifice plate is less than the thickness of the explosion-proof valve body.

8. The cap assembly according to claim 6, characterized in that, A first sealing element is provided between the orifice plate and the explosion-proof valve body. The first sealing element has a first through hole, and the connection between the orifice plate and the bottom of the second groove is located in the first through hole.

9. The cap assembly according to any one of claims 1 to 8, characterized in that, The cap assembly also includes a second sealing element, which has a second through hole. The top cover and the explosion-proof valve are disposed in the second through hole, and the outer wall of the annular flange is in contact with the hole wall of the second through hole.

10. A battery cell, characterized in that, include: The housing has a cavity and an opening communicating with the cavity; An electrode assembly is disposed within the cavity, and an electrode tab is provided at the end of the electrode assembly facing the opening; The cap assembly according to any one of claims 1 to 9 covers and seals the opening, the top cover is located outside the housing, and the explosion-proof valve is connected to the electrode lug.

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