Cylindrical lithium battery roll groove sealing structure and sealing process

Abstract

This invention discloses a cylindrical lithium battery roll groove sealing structure and sealing process, relating to the field of lithium battery packaging technology. It includes a cylindrical lithium battery roll groove sealing structure comprising a battery casing. From bottom to open end, the battery casing has a current-carrying disk, a diaphragm, and a steel cap arranged sequentially. A roll groove is provided at the open end of the battery casing, and a sealing ring is provided on the inner wall of the roll groove. The diaphragm and steel cap are both confined within the sealing ring, and the current-carrying disk is located below the diaphragm. This invention optimizes the sealing structure design, increasing the edge width of the battery casing opening to >4mm while retaining a flat platform structure >2mm. Simultaneously, the inner diameter of the roll groove is reduced by 1-2mm compared to conventional sizes. This solves the technical pain point of traditional roll groove sealing, which, due to narrow edges and lack of a flat platform, cannot achieve simultaneous welding of positive and negative electrodes. This allows the mature and low-cost roll groove sealing process to be re-adapted to the production of large cylindrical batteries, significantly reducing the overall production cost of large cylindrical batteries.

Description

Technical Field

[0001] This invention relates to the field of lithium battery packaging technology, specifically to a cylindrical lithium battery roll groove sealing structure and sealing process. Background Technology

[0002] In the production of large cylindrical batteries, welding the positive and negative electrodes on the same side has become an important development direction for optimizing battery pack structure, improving production efficiency and product quality. Welding the positive and negative electrodes on the same side can significantly simplify the overall structural design of the battery pack, reduce the difficulty of welding operations, improve welding efficiency and welding quality stability, and at the same time make it easier to achieve safe control under battery thermal runaway conditions, meeting the industry's stringent requirements for battery safety.

[0003] However, due to its structural limitations, the traditional roller groove sealing process cannot meet the requirements of welding positive and negative electrodes on the same side, leading to its gradual elimination in the production of large cylindrical batteries. Nevertheless, the roller groove sealing process has significant advantages such as mature technology, low production cost, high structural reliability, and high product qualification rate. If it can be reasonably improved to adapt to the requirements of welding positive and negative electrodes on the same side, it can effectively reduce the overall production cost of large cylindrical batteries while retaining its inherent advantages, and has extremely high industrial application value.

[0004] Currently, most mainstream cylindrical batteries in the industry adopt a single safety valve structure. This structure can only release gas when the internal pressure of the battery reaches the safety limit. It cannot provide circuit protection against common battery safety hazards such as overcharging and short circuits, and its safety protection performance is significantly insufficient. In contrast, the traditional roller groove sealing process, after improvement, can retain two explosion-proof protection functions, namely the first explosion-proof power-off treatment and the second flip-open cracking pressure relief treatment. Its safety protection effect is better than the existing single safety valve structure, and it can more comprehensively deal with safety risks such as battery overcharging and short circuits, further improving the overall safety performance of the battery.

[0005] Based on the above situation, it is urgent to improve the traditional roller groove sealing process so that it can meet the requirements of welding the positive and negative electrodes on the same side of large cylindrical batteries, while retaining its advantages of mature technology, low cost and excellent safety performance, and solving the problems of high cost and insufficient safety protection in the existing technology, so as to promote the high-quality development of the large cylindrical battery industry. Summary of the Invention

[0006] The purpose of this invention is to provide a cylindrical lithium battery roller groove sealing structure and sealing process to solve the problems mentioned in the background art.

[0007] To achieve the above objectives, the present invention provides the following technical solution: a cylindrical lithium battery roll groove sealing structure, comprising a cylindrical lithium battery casing, wherein an electrode current disk, a diaphragm, and a steel cap are sequentially arranged from bottom to open end of the battery casing, a roll groove is provided at the open end of the battery casing, a sealing ring is provided on the inner wall of the roll groove, the diaphragm and the steel cap are both confined within the sealing ring, and the electrode current disk is located below the diaphragm. The polar current plate has a poor solder joint in the middle. The diaphragm includes an explosion-proof aluminum sheet and a bursting aluminum sheet. There are connection marks between the explosion-proof aluminum sheet and the bursting aluminum sheet. The poor solder joint is connected to the middle of the bursting aluminum sheet through a poor soldering process. The bursting aluminum sheet can be separated from the polar current plate and the explosion-proof aluminum sheet under a set pressure. An annular notch is formed below the roller groove. The diameter of the polar flow disk is matched with or smaller than the inner wall diameter of the annular notch. The edge width of the battery case opening is >4mm, and a flat platform structure of >2mm is retained at the edge. The inner diameter of the roller groove is 1-2mm smaller than the conventional size.

[0008] Furthermore, the connection grooves are formed by either soldering or die-cutting, and the blasting aluminum sheet separates from the explosion-proof section aluminum sheet under a pressure of 1.3-1.6 MPa.

[0009] Further, regarding this scheme, the blasting aluminum sheet breaks off from the poorly welded part of the polar flow plate under a pressure of 1.0-1.3 MPa, and under this pressure, the blasting aluminum sheet does not separate from the explosion-proof section aluminum sheet but undergoes deformation.

[0010] Further, the steel cap includes a ring section, which is smooth and flat. The explosion-proof aluminum sheet has a smooth and flat ring that fits into the ring section. After the two are fitted together, they rest on the stepped surface inside the roller groove and are fixed and limited by a sealing ring.

[0011] Further, the steel cap has a cross seal in the middle, which rises from the connection with the ring section toward the axis. The inner side of the ring section has a bent edge that abuts against the top of the explosion-proof section aluminum sheet. The connection groove is located near the bent edge.

[0012] A cylindrical lithium battery roller groove sealing process based on the above structure employs a novel tooling comprising several circumferentially distributed abutments. The bottom of each abutment is horizontal and can be attached to the periphery of the steel cap, while the end furthest from the battery casing is curved and connected to a control mechanism that controls the lifting and lateral movement of the abutments. The process includes at least the following steps: Step 1: After installing the battery cell, install the polar current plate, diaphragm, and steel cap in sequence; Step 2: Control the foot to descend vertically and place it against the surrounding surface of the steel cap; Step 3: Control the movement of the abutment feet and position them against the inner wall of the sealing ring; Step 4: Gradually rotate and wrap the edge by squeezing the battery casing, gradually removing the foot during the wrapping process until the edge is sealed. Step 5: Level the sealing surface.

[0013] Further, regarding this scheme, the gradual rotational binding involves at least four rotational extrusion actions, as seen from a cross-sectional perspective: The first rotation controls the edge of the battery case to tilt 15°-30° toward the axis, while simultaneously controlling the foot to slightly move toward the axis. The second rotation of the edge control tilts the battery case edge position 15°-30° toward the axis again, and the foot is then slightly moved toward the axis again. The third rotation of the edge control tilts the edge of the battery case 15°-25° toward the axis again, and then the foot is pulled out; The fourth rotation controls the edge of the battery casing to be aligned with the top plane of the steel cap, and then it is leveled.

[0014] To go a step further with this solution, after the diaphragm and steel cap are installed with the sealing ring in advance, the rotation and edge-wrapping operations in steps two through five are then performed.

[0015] Further, during the sealing process, a support platform is used to provide stable support for the battery casing. The support platform is locked in the roller groove to prevent the battery from shaking or shifting.

[0016] Further, the control mechanism can be an integrated device that can simultaneously control the lifting and lateral movement of each foot; or it can be several separate devices that can simultaneously control the lifting and lateral movement of each foot.

[0017] Compared with the prior art, the beneficial effects of the present invention are: This cylindrical lithium battery roller groove sealing structure and sealing process optimizes the sealing structure design, increasing the edge width of the battery casing opening to >4mm while retaining a flat platform structure of >2mm. At the same time, the inner diameter of the roller groove is reduced by 1-2mm compared to the conventional size. This solves the technical pain point of traditional roller groove sealing, which cannot achieve welding of the positive and negative electrodes on the same side due to narrow edge and lack of flat platform. It makes the mature and low-cost roller groove sealing process suitable for the production of large cylindrical batteries, significantly reducing the overall production cost of large cylindrical batteries while balancing production efficiency and product quality.

[0018] Meanwhile, a new type of tooling with circumferentially distributed feet is adopted, combined with a four-stage rotating edge-wrapping process. By gradually tilting the edge and simultaneously adjusting the position of the feet, problems such as wave deformation and structural displacement caused by cell shrinkage that occur in the traditional edge-wrapping process are effectively avoided, ensuring the flatness of the edge-wrapping. At the same time, the design of the support table engaging the roller groove can prevent the battery from shaking as a whole, further improving the sealing accuracy. The optimized design that allows the diaphragm and steel cap to be pre-assembled with the sealing ring reduces the packaging difficulty, reduces processing defects caused by sealing ring deformation, and significantly improves the product qualification rate.

[0019] Furthermore, compared to the mainstream single safety valve structure in the industry, which can only achieve single pressure relief protection, this invention achieves two-stage explosion protection through the poor welding connection between the polar current plate and the diaphragm burst aluminum sheet, and the connection groove design between the explosion-proof section aluminum sheet and the burst aluminum sheet. The first stage is under a pressure of 1.0-1.3 MPa, the burst aluminum sheet and the poor welding part of the polar current plate break off, achieving power-off protection and preventing the further expansion of safety hazards; the second stage is under a pressure of 1.3-1.6 MPa, the burst aluminum sheet separates from the explosion-proof section aluminum sheet, achieving gas depressurization. This dual protection can comprehensively cope with common safety risks such as battery overcharging and short circuits, significantly improving the safety of battery use. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the external structure of the cylindrical lithium battery of the present invention; Figure 2 This is a top-view structural diagram of the sealing structure of the present invention; Figure 3 This is a cross-sectional view of the sealing structure of the present invention. Figure 4 This is a three-dimensional structural diagram of the sealing structure of the present invention from a cross-sectional perspective; Figure 5 This is a schematic diagram of the tooling position structure of the sealing structure of the present invention under the sealing process condition; Figure 6 For the present invention Figure 3 Enlarged structural diagram of section A; Figure 7 This is a schematic diagram of the diaphragm structure of the present invention; Figure 8 This is a schematic diagram of the polar flow disk structure of the present invention; Figure 9 This is a schematic diagram of the steel cap structure of the present invention; Figure 10 This is a schematic diagram of the roller groove position structure of the cylindrical lithium battery casing of the present invention.

[0021] In the diagram: 1. Battery casing; 101. Roller groove; 102. Annular notch; 2. Polar flow plate; 201. Poor weld section; 3. Diaphragm; 301. Explosion-proof aluminum sheet; 302. Explosion-proof aluminum sheet; 303. Connection groove; 4. Sealing ring; 5. Steel cap; 501. Ring section; 502. Cross seal; 503. Bending edge; 6. Foot; 7. Support platform. Detailed Implementation

[0022] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0023] like Figures 1 to 3 As shown, the present invention provides a technical solution: a cylindrical lithium battery roller groove sealing structure and sealing process, including a cylindrical lithium battery casing 1, wherein the battery casing 1 is provided with an polar current disk 2, a diaphragm 3 and a steel cap 5 in sequence from bottom to open end, a roller groove 101 is provided at the open end of the battery casing 1, and a sealing ring 4 is provided on the inner wall of the roller groove 101, the diaphragm 3 and the steel cap 5 are both confined within the sealing ring 4, and the polar current disk 2 is located below the diaphragm 3; like Figure 4 as well as Figure 10 As shown, to ensure the smooth implementation of the above embodiments, it is necessary to understand that during the formation of the roller groove 101, an annular notch 102 is also formed below the roller groove 101. During the battery packaging process, the height of the battery cell generally reaches the annular notch 102 and abuts against the bottom inner wall of the annular notch 102. The polar flow disk 2 is located at the top of the battery cell, and its diameter is matched with the inner wall diameter of the annular notch 102, or at least its diameter is smaller than the inner wall diameter of the annular notch 102.

[0024] like Figure 4 As shown, in this embodiment, the diaphragm 3 and steel cap 5 are limited by the setting of the roller groove 101. In order to ensure the overall safety of the battery and the connection of the subsequent battery pack, the improvement method is mainly to expand the area of ​​the sealing edge. Since the previous sealing edge width was very small, there was no flat platform to provide a basis for the subsequent battery pack welding, and it was impossible to achieve single-sided welding of the positive and negative electrodes on the same side. In this embodiment, the sealing edge area is reserved as a platform structure of >2mm to ensure that there is enough space for subsequent battery pack welding and single-sided welding of the negative electrode. like Figure 4As shown, in order to ensure the smooth implementation of the above embodiments, this embodiment completely changes the overall structure of the roller groove sealing. First, the inner diameter of the roller groove 101 is changed. After the sealing edge is enlarged, its own support platform needs to be larger. Therefore, the inner diameter of the roller groove 101 is 1-2mm smaller than the traditional size. Under the condition of the strength of the battery shell 1 material, the inner diameter of the roller groove 101 is even less than 2mm. In addition, the width of the edging needs to be improved. The traditional edging size is generally around 2mm, and now it needs to reach a edging width of >4mm. During the edging process, care must be taken because the battery cell will shrink during the edging process. If the traditional method is used to directly squeeze, it will cause wavy deformation of the edging. Now, by rotating the edging at multiple angles and compressing it little by little with a mold, it is ensured that even with an edging size of >4mm, there is still no wavy deformation at the edging position. The flat part can be more than 2mm, providing a stable platform structure.

[0025] like Figure 5 As shown, to achieve the above objectives, this embodiment provides a novel sealing process employing a new type of tooling. This tooling includes several feet 6 arranged in a circular pattern. The bottom of each foot 6 is horizontal and can adhere to the peripheral plane of the steel cap 5. The end of each foot 6 away from the housing is curved, and this curved end is connected to a control mechanism for controlling the position of the foot 6. This control mechanism is a device capable of controlling the raising, lowering, and lateral movement of each foot 6. This device can be integrated, capable of simultaneously controlling the raising, lowering, and lateral movement of each foot 6; or it can consist of several separate devices capable of simultaneously controlling the raising, lowering, and lateral movement of each foot 6. Therefore, in this embodiment, this novel sealing process includes at least the following steps: Step 1: After the battery cell is installed, install the polar current plate 2, diaphragm 3 and steel cap 5 in sequence; Step 2: Control the foot 6 to descend vertically and attach it to the perimeter of the steel cap 5; Step 3: Control the movement of the foot 6 until it abuts against the inner wall of the sealing ring 4; Step 4: Gradually rotate and wrap the edge by squeezing the battery casing 1, and gradually pull out the foot 6 during the wrapping process until the edge sealing of the lithium battery is completed. Step 5: Level the sealing surface.

[0026] Unlike traditional edge binding, the gradual rotation edge binding achieves the edge binding action of the battery shell 1 through several rotation and compression actions. In this embodiment, the gradual rotation edge binding is divided into at least four rotation edge binding actions of different degrees. From the cross-sectional view, the first rotation edge binding controls the edge binding position of the battery shell 1 to tilt towards the axis by about 15°-30°. At this time, the control foot 6 is slightly translated towards the axis. The second rotation edge binding controls the edge binding position of the battery shell 1 to tilt towards the axis again by about 15°-30°. At this time, the control foot 6 is again slightly translated towards the axis. The third rotation edge binding controls the edge binding position of the battery shell 1 to tilt towards the axis again by about 15°-25°. Finally, the control foot 6 is pulled out. The fourth rotation edge binding controls the edge binding position of the battery shell 1 to be attached to the plane of the top of the steel cap 5, flattened, and the edge binding action is completed. As an alternative embodiment, unlike traditional edge wrapping, the gradual rotation edge wrapping gradually achieves the edge wrapping action of the battery casing 1 through several rotation and compression actions. In this embodiment, since the new sealing process can avoid the compression of the sealing structure and the battery cell and reduce the wrinkling phenomenon, the diaphragm 3 and the steel cap 5 can be installed with the sealing ring 4 in advance, and then the gradual rotation edge wrapping is carried out in the same way as above. This can avoid the increased processing difficulty caused by the deformation of the sealing ring 4 and reduce the packaging difficulty.

[0027] like Figure 5 As shown, it is also necessary to understand the above embodiments that, during the sealing process of the cylindrical lithium battery, a support platform 7 is used to provide stable support for the battery casing 1. The support platform 7 is locked at the roller groove 101 to ensure that the battery as a whole will not shake or shift during the edge sealing operation, and to reduce the deformation of the internal cells and sealing structure of the cylindrical lithium battery during the edge sealing process.

[0028] like Figure 5 , Figure 6 as well as Figure 7 As shown, to ensure the smooth implementation of this embodiment, it is also necessary to understand that the diaphragm 3 includes an explosion-proof aluminum sheet 301 and a ruptureable aluminum sheet 302. A connection groove 303 is provided between the explosion-proof aluminum sheet 301 and the ruptureable aluminum sheet 302. The connection groove 303 is formed by a false weld or a pressing, which means that the explosion-proof aluminum sheet 301 and the ruptureable aluminum sheet 302 can separate under certain conditions. In this embodiment, the ruptureable aluminum sheet 302 can detach from the explosion-proof aluminum sheet 301 at 1.3-1.6 MPa.

[0029] like Figure 5 , Figure 6 and Figure 8As shown, it is also necessary to understand that a poorly welded part 201 is provided in the middle of the polar current plate 2. The poorly welded part 201 is connected to the middle of the blasting aluminum sheet 302 through a poorly welded process. That is to say, the polar current plate 2 can also be separated from the explosion-proof aluminum sheet 301 under certain conditions. In this embodiment, the blasting aluminum sheet 302 separates from the polar current plate 2 at 1.0-1.3 MPa.

[0030] To facilitate understanding of the above embodiments, it is necessary to understand that, under the setting of the connecting groove 303, at 1.0-1.3 MPa, although the bursting aluminum sheet 302 does not detach from the explosion-proof section aluminum sheet 301, it will also deform under pressure and break off from the poorly welded part 201 under the deformation.

[0031] like Figure 5 and Figure 9 As shown, to ensure the smooth implementation of this embodiment, it is also necessary to understand that the steel cap 5 includes a ring section 501, which is smooth and flat as a whole. The explosion-proof aluminum sheet 301 also has a smooth and flat ring section. The steel cap 5 is attached to the plane of the explosion-proof aluminum sheet 301 and rests on the inner stepped surface of the roller groove 101. It is fixed and limited by the sealing ring 4. A cross seal 502 is also provided in the middle of the steel cap 5. The cross seal 502 extends from the connection with the ring section 501 toward the shaft. The raised center provides space for the detachment of the explosive aluminum sheet 302. In addition, a bent edge 503 is provided on the inner side of the annular section 501. After the steel cap 5 is attached to the explosion-proof aluminum sheet 301, the bent edge 503 abuts against the top of the explosion-proof aluminum sheet 301, providing more stable conditions for the explosion-proof aluminum sheet 301. At the same time, the connecting groove 303 should be set near the bent edge 503 to reduce the deformation of the explosion-proof aluminum sheet 301 and facilitate the detachment of the explosive aluminum sheet 302.

[0032] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended embodiments and their equivalents.

Claims

1. A cylindrical lithium battery roll groove sealing structure, comprising a cylindrical lithium battery casing (1), wherein the battery casing (1) is provided with an polar current disk (2), a diaphragm (3) and a steel cap (5) sequentially from bottom to open end, a roll groove (101) is provided at the open end of the battery casing (1), a sealing ring (4) is provided on the inner wall of the roll groove (101), the diaphragm (3) and the steel cap (5) are both confined within the sealing ring (4), and the polar current disk (2) is located below the diaphragm (3), characterized in that: The polar flow plate (2) has a poor solder joint (201) in the middle. The diaphragm (3) includes an explosion-proof aluminum sheet (301) and a rupture aluminum sheet (302). A connection groove (303) is provided between the explosion-proof aluminum sheet (301) and the rupture aluminum sheet (302). The poor solder joint (201) is connected to the middle of the rupture aluminum sheet (302) through a poor solder joint process. The rupture aluminum sheet (302) can be separated from the polar flow plate (2) and the explosion-proof aluminum sheet (301) under a set pressure. An annular notch (102) is formed below the roller groove (101). The diameter of the polar flow disk (2) is matched with or smaller than the inner wall diameter of the annular notch (102). The edge width of the opening end of the battery case (1) is >4mm, and a flat platform structure of >2mm is retained at the edge. The inner diameter of the roller groove (101) is 1-2mm smaller than the conventional size.

2. The cylindrical lithium battery roller groove sealing structure according to claim 1, characterized in that: The connecting groove (303) is formed by welding or stamping, and the blasting aluminum sheet (302) is separated from the explosion-proof aluminum sheet (301) under a pressure of 1.3-1.6 MPa.

3. The cylindrical lithium battery roller groove sealing structure according to claim 1, characterized in that: The blasting aluminum sheet (302) breaks off from the poor weld (201) of the polar flow plate (2) under a pressure of 1.0-1.3 MPa, and the blasting aluminum sheet (302) does not separate from the explosion-proof section aluminum sheet (301) under this pressure but undergoes deformation.

4. The cylindrical lithium battery roller groove sealing structure according to claim 1, characterized in that: The steel cap (5) includes a ring section (501). The ring section (501) is smooth and flat. The explosion-proof aluminum sheet (301) has a smooth and flat ring that fits into the ring section (501). After the two are fitted together, they are placed on the inner stepped surface of the roller groove (101) and fixed and limited by the sealing ring (4).

5. The cylindrical lithium battery roller groove sealing structure according to claim 4, characterized in that: The steel cap (5) is provided with a cross seal (502) in the middle. The cross seal (502) rises from the connection with the ring section (501) toward the axis. The inner side of the ring section (501) is provided with a bent edge (503). The bent edge (503) abuts against the top of the explosion-proof section aluminum sheet (301). The connection groove (303) is set near the bent edge (503).

6. A cylindrical lithium battery roll groove sealing process, applied to the cylindrical lithium battery roll groove sealing structure as described in any one of claims 1-5, characterized in that: A new type of tooling is adopted, which includes several circumferentially distributed feet (6). The bottom of the feet (6) is horizontal and attached to the periphery of the steel cap (5). The end away from the battery case (1) is raised and connected to a control mechanism that can control the lifting and lateral movement of the feet (6). The process includes at least the following steps: Step 1: After the battery cell is installed, install the polar current plate (2), diaphragm (3) and steel cap (5) in sequence. Step 2: Control the foot (6) to descend vertically and attach it to the periphery of the steel cap (5); Step 3: Control the movement of the foot (6) to abut against the inner wall of the sealing ring (4); Step 4: Gradually rotate and wrap the edge by squeezing the battery casing (1), and gradually remove the foot (6) during the wrapping process until the edge is sealed. Step 5: Level the sealing surface.

7. The cylindrical lithium battery roll groove sealing process according to claim 6, characterized in that: The gradual rotational binding involves at least four rotational extrusion actions, as seen from a cross-sectional perspective: The first rotation of the edge control battery case (1) tilts the edge position towards the axis by 15°-30°, while controlling the foot (6) to move slightly towards the axis; The second rotation of the edge control battery case (1) tilts the edge position towards the axis again by 15°-30°, and the control foot (6) moves slightly towards the axis again; The third rotation of the edge control battery case (1) tilts the edge position towards the axis again by 15°-25°, and then the foot (6) is pulled out. The fourth rotation of the edge control battery case (1) is placed on the top plane of the steel cap (5) and then leveled.

8. The cylindrical lithium battery roll groove sealing process according to claim 6, characterized in that: After the diaphragm (3) and steel cap (5) are installed with the sealing ring (4) in advance, the rotation and edge wrapping operations in steps two to five are performed.

9. The cylindrical lithium battery roll groove sealing process according to claim 6, characterized in that: During the sealing process, a support platform (7) is used to provide stable support for the battery casing (1). The support platform (7) is locked at the roller groove (101) to prevent the battery from shaking or shifting.

10. The cylindrical lithium battery roll groove sealing process according to claim 6, characterized in that: The control mechanism is an integrated device that simultaneously controls the lifting and lateral movement of each foot (6); or it can be several separate devices that simultaneously control the lifting and lateral movement of each foot (6).

Images