Battery cell cover plate assembly, battery cell and battery pack

Abstract

The invention relates to the technical field of batteries, and discloses a battery cell cover plate assembly, a battery cell and a battery pack. The battery cell cover plate assembly comprises a cover plate, an anti-explosion valve, a plastic part and a supporting structure, the cover plate is provided with an assembly hole; the anti-explosion valve is arranged in the assembly hole; the plastic part is arranged on the first surface of the cover plate; the supporting structure is arranged between the cover plate and the plastic part, the melting point of the supporting structure is higher than that of the plastic part, the supporting structure is suitable for being supported between the pole group and the cover plate after the plastic part is melted due to high temperature in the battery cell, an exhaust channel communicated with the anti-explosion valve is formed, the supporting structure comprises a supporting plate corresponding to the anti-explosion valve in position, and the supporting plate is provided with a plurality of exhaust holes; the proportional relation between the areas of all the parts and the proportional relation between the areas of all the parts and the capacity of the battery cell meet preset conditions. When thermal runaway of the battery cell occurs, the supporting structure can keep the exhaust channel communicated with the anti-explosion valve between the pole group and the cover plate, so that the exhaust of the anti-explosion valve is not influenced, and the safety performance of the battery cell is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of batteries, and in particular to a battery cover assembly, a battery cell and a battery pack. Background Art

[0002] Lithium-ion batteries have become the representative of modern high-performance batteries due to their high operating voltage, high specific energy, large capacity, low self-discharge, good cycle performance, long service life, light weight and small size.

[0003] Long-cell lithium-ion batteries are usually designed with tabs on both sides, and their structure includes: cell cover assembly, shell, pole group, electrolyte, etc. The cell cover assembly integrates structural parts such as pole column, explosion-proof valve and injection hole. After the cell cover assembly and the shell are welded, a closed space with a certain mechanical strength is formed to protect the pole group. The pole tabs on both sides of the pole group are fixed to the base of the pole column on both sides of the cover by laser welding to achieve electrical connection. The length direction of the cell is mainly fixed by the lower plastic insulating material on the inner side of the cover pressing on the pole group. The cover is integrated with an explosion-proof valve structure, which is mainly used for the directional discharge of internal high-temperature and high-pressure gas when the battery has thermal runaway due to internal short circuit, thereby improving the safety performance of the battery.

[0004] When this type of battery cell generates high temperature inside, the lower plastic will melt, causing its fixing effect on the electrode group to fail. The high-temperature and high-pressure gas inside the battery cell is exhausted in the direction of the explosion-proof valve. Under the push of the high-temperature and high-pressure gas, the electrode group will move toward the explosion-proof valve and block the explosion-proof valve, causing the exhaust channel to be blocked, thereby affecting the pressure relief effect of the battery cell and reducing the safety performance of the battery cell. Summary of the invention

[0005] In view of this, the present invention provides a battery cover assembly, a battery cell and a battery pack to solve the problem that when the high temperature generated inside the battery cell causes the lower plastic to melt, the electrode group blocks the explosion-proof valve and affects the exhaust pressure relief.

[0006] In the first aspect, the present invention provides a battery cell cover plate assembly, including a cover plate, an explosion-proof valve, a plastic part, and a support structure. The cover plate is provided with an assembly hole, and the cover plate has a first surface facing the pole group of the battery cell; the explosion-proof valve is provided in the assembly hole; the plastic part is provided on the first surface of the cover plate; the support structure is provided between the cover plate and the plastic part, the melting point of the support structure is higher than the melting point of the plastic part, the support structure is suitable for supporting between the pole group and the cover plate after the plastic part melts due to the high temperature inside the battery cell, forming an exhaust channel connected to the explosion-proof valve, the support structure includes a bracket corresponding to the position of the explosion-proof valve, the bracket is provided with a plurality of exhaust holes facing the explosion-proof valve, and the area of ​​the explosion-proof valve is S1, unit is mm 2 The total area of ​​the exhaust holes is S2, in mm 2 The effective supporting area of ​​the support plate to the electrode group of the battery cell is S3, in mm 2The capacity of the battery cell formed by the battery cell cover assembly is A, unit Ah, satisfying: S1 / A≥1.08, S3 / A≥2.0, S2≥1.2S1.

[0007] Beneficial effect: The battery cover plate assembly provided by the present invention is provided with an explosion-proof valve protection structure. By setting a support structure with a melting point greater than that of the plastic part, when high-temperature and high-pressure gas is generated inside the battery, the plastic part melts and fails. At this time, the support structure is not melted, and the pole group has a tendency to move toward the explosion-proof valve under the action of the high-temperature and high-pressure gas. At this time, the support structure can effectively support and fix the pole group to avoid the pole group randomly moving with the high-temperature and high-pressure airflow to block the explosion-proof valve on the cover plate and affect the exhaust effect of the explosion-proof valve when the battery cell is thermally runaway. The support structure allows the pole group and the cover plate to maintain an exhaust channel connected to the explosion-proof valve, ensuring that the exhaust of the explosion-proof valve is not affected, thereby improving the safety performance of the battery cell. Since the support structure and the explosion-proof valve are arranged in a corresponding position, by controlling the proportional relationship between the areas of each part, and controlling the proportional relationship between the areas of each part and the battery cell capacity, it can be ensured that the support structure can reduce the blocking ratio of the support structure to the explosion-proof valve while supporting the pole group and maintaining the exhaust channel, thereby ensuring the exhaust effect of the explosion-proof valve.

[0008] In an optional embodiment, the bracket includes a support plate facing the explosion-proof valve and at least two support legs arranged on the edge of the support plate, and the exhaust hole is arranged on the support plate.

[0009] In an optional implementation, along the thickness direction of the cover plate, the exhaust hole is located within the projection range of the explosion-proof valve.

[0010] In an optional embodiment, the support structure further includes a boss disposed on the first surface of the cover plate, the boss is disposed corresponding to the supporting feet, and each supporting foot is connected to a boss.

[0011] In an optional embodiment, two groups of bosses are provided, which are respectively located on both sides of the explosion-proof valve.

[0012] In an optional embodiment, the support plate is provided with a window, the inner wall of the window is connected with reinforcing ribs, the reinforcing ribs are arranged at intervals or staggered, and the gaps between adjacent reinforcing ribs and / or between the reinforcing ribs and the inner wall of the window constitute exhaust holes.

[0013] In an optional embodiment, the support plate is provided with a plurality of exhaust holes; and / or, an exhaust gap communicating with the exhaust channel is provided between the support foot, the support plate and the cover plate.

[0014] In an optional embodiment, the height of the exhaust channel is H, 3mm≤H≤6mm.

[0015] In a second aspect, the present invention further provides a battery cell, comprising a shell, a pole group and the battery cell cover assembly in the above technical solution, wherein the shell has an open end; the pole group is arranged in the shell; the battery cell cover assembly is arranged at the open end of the shell to encapsulate the pole group in the shell.

[0016] Beneficial effect: Because the battery cell includes the battery cell cover plate assembly, it has the same effect as the battery cell cover plate assembly and will not be described in detail here.

[0017] In a third aspect, the present invention further provides a battery pack, comprising the battery cell in the above technical solution.

[0018] Beneficial effect: Since the battery pack includes the battery cell, it has the same effect as the battery cell and will not be described in detail here. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0020] Figure 1 The figure is a schematic diagram of the exploded structure of an existing battery cell;

[0021] Figure 2 It is a partial structural schematic diagram of a battery cell cover plate assembly according to an embodiment of the present invention;

[0022] Figure 3 for Figure 2 Schematic diagram of the structure of the middle cover plate and the boss;

[0023] Figure 4 A schematic diagram of the structure of a bracket;

[0024] Figure 5 This is a schematic structural diagram of a battery cell according to an embodiment of the present invention;

[0025] Figure 6 for Figure 5 Schematic diagram of the exploded structure of the battery cell shown;

[0026] Figure 7 for Figure 5 A top view of the battery cell shown;

[0027] Figure 8 for Figure 7 Sectional view along AA;

[0028] Fig. 9 for Figure 8 A magnified view of the local structure.

[0029] Description of reference numerals:

[0030] 1. Cell cover assembly; 11. Cover; 12. Explosion-proof valve; 13. Plastic parts; 14. Support structure; 141. Boss; 142. Bracket; 1421. Support plate; 1422. Support foot; 1423. Exhaust hole; 1424. Exhaust gap; 1425. Window; 1426. Reinforcement rib; 15. Exhaust channel; 2. Shell; 3. Pole group. DETAILED DESCRIPTION

[0031] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0032] At present, traditional batteries, such as Figure 1 As shown, the battery cell includes a shell, both ends of the shell are open, and two battery cover plate assemblies are arranged at the two open ends. The battery cover plate assembly integrates a cover plate, a pole, an explosion-proof valve and a plastic part. A pole group is arranged in the shell, and the plastic part is between the cover plate and the pole group to support and fix the pole group.

[0033] In the length direction of the battery cell, the electrode group is mainly insulated and fixed by the lower plastic in the battery cell cover assembly, but this insulating material is generally made of PP material, and its strength and high temperature resistance are very limited, generally around 150 degrees Celsius, but the temperature at which the battery cell undergoes thermal runaway is usually much higher than the melting point of these insulating materials. When thermal runaway occurs, these fixed structures inside the battery cell have melted and failed. At this time, only the electrode group is left inside the battery cell, and due to the melting of the insulating protective material, the gap between the electrode group and the cover and shell is increased. At this time, the electrode group has a high degree of freedom inside the battery cell. Since the high-temperature and high-pressure gas is exhausted in the direction of the explosion-proof valve, the electrode group will randomly move with the high-temperature and high-pressure airflow and block the explosion-proof valve on the cover, thereby blocking the exhaust channel, greatly reducing the exhaust effect of the explosion-proof valve and reducing the safety performance of the battery cell.

[0034] Combine the following Figures 2 to 9 , describing an embodiment of the present invention.

[0035] According to an embodiment of the present invention, in a first aspect, a battery cell cover plate assembly 1 is provided, comprising a cover plate 11, an explosion-proof valve 12, a plastic part 13 and a support structure 14. The cover plate 11 is provided with an assembly hole, and the cover plate 11 has a first surface facing the pole group 3 of the battery cell; the explosion-proof valve 12 is provided in the assembly hole; the plastic part 13 is provided on the first surface of the cover plate 11; the support structure 14 is provided between the cover plate 11 and the plastic part 13, the melting point of the support structure 14 is higher than the melting point of the plastic part 13, the support structure 14 is suitable for supporting between the pole group 3 and the cover plate 11 after the plastic part 13 melts due to the high temperature inside the battery cell, and forming an exhaust channel 15 connected with the explosion-proof valve 12, the support structure 14 includes a bracket 142 corresponding to the position of the explosion-proof valve 12, the bracket 142 is provided with a plurality of exhaust holes 1423, and the area of ​​the explosion-proof valve 12 is S1, in mm 2 The total area of ​​the exhaust holes 1423 is S2, in mm 2 The effective supporting area of ​​the bracket 142 for the electrode group 3 of the battery cell is S3, in mm 2 The capacity of the battery cell formed by the battery cell cover assembly is A, unit Ah, satisfying: S1 / A≥1.08, S3 / A≥2.0, S2≥1.2S1.

[0036] The battery cell cover plate assembly 1 provided by the present invention is provided with an explosion-proof valve 12 protection structure. By providing a support structure 14 with a melting point greater than that of the plastic part 13, when high-temperature and high-pressure gas is generated inside the battery cell, the plastic part 13 melts and fails. At this time, the support structure 14 has not melted, and the pole group 3 has a tendency to move toward the explosion-proof valve 12 under the action of the high-temperature and high-pressure gas. At this time, the support structure 14 can effectively support and fix the pole group 3 to avoid the pole group 3 randomly moving with the high-temperature and high-pressure airflow to block the explosion-proof valve 12 on the cover plate 11 and affect the exhaust effect of the explosion-proof valve 12 when thermal runaway occurs in the battery cell. The support structure 14 allows the pole group 3 and the cover plate 11 to maintain an exhaust channel 15 connected to the explosion-proof valve 12, thereby ensuring that the exhaust of the explosion-proof valve 12 is not affected, thereby improving the safety performance of the battery cell. Since the support structure 14 and the explosion-proof valve 12 are arranged in corresponding positions, by controlling the proportional relationship between the areas of each part and the proportional relationship between the area of ​​each part and the capacity of the battery cell, S1 / A≥1.08; S3 / A≥2.0 and S2≥1.2S1 are satisfied, so that the support structure 14 can reduce the blocking ratio of the explosion-proof valve 12 by the support structure 14 while supporting the electrode group 3 and maintaining the exhaust channel 15, thereby ensuring the exhaust effect of the explosion-proof valve 12.

[0037] In some embodiments, the bracket 142 includes a support plate 1421 and at least two legs 1422 disposed on the edge of the support plate 1421 , and the exhaust hole 1423 is disposed on the support plate 1421 .

[0038] By providing the support feet 1422 on the edge of the support plate 1421 , the bracket 142 can be stably connected to the cover plate 11 through the support feet 1422 .

[0039] Specifically, the support plate 1421 effectively supports the electrode group 3. The total area of ​​the region occupied by the support plate 1421 is S, then, S3=S-S2.

[0040] Furthermore, the support legs 1422 are used. Compared with the technical solution of the long strip flange formed outward by the support plate 1421, the support legs 1422 can make an exhaust gap 1424 exist between the support plate 1421 and the cover plate 11, further improving the flowability of the gas in the exhaust channel 15. At the same time, the material used for the support 142 can be reduced, and the overall weight of the battery cover plate assembly 1 can be reduced.

[0041] When thermal runaway occurs inside the battery cell, the bracket 142 first supports the electrode group 3, so that the exhaust channel 15 is maintained between the electrode group 3 and the explosion-proof valve 12. In addition, the exhaust holes 1423 on the support plate 1421 and the exhaust gap 1424 in the height direction of the support leg 1422, the bracket 142 and the cover plate 11 are connected to the exhaust channel 15, which can ensure the exhaust requirements.

[0042] In some embodiments, along the thickness direction of the cover plate 11 , the exhaust hole 1423 is located within the projection range of the explosion-proof valve 12 .

[0043] This arrangement can effectively prevent internal combustion products from erupting outward through the explosion-proof valve 12 when thermal runaway occurs in the battery cell, thereby improving the safety performance of the battery cell.

[0044] In some embodiments, the support structure 14 further includes a boss 141 disposed on the first surface of the cover plate 11 . The boss 141 is disposed correspondingly to the legs 1422 , and each leg 1422 is connected to a boss 141 .

[0045] The support structure 14 adopts the structural form of the boss 141 and the bracket 142, which can facilitate the connection between the bracket 142 and the cover plate 11. Since the bracket 142 is connected to the boss 141, the bracket 142 and the boss 141 together constitute the protection structure of the explosion-proof valve 12. When the battery cell has thermal runaway and the plastic part 13 melts and fails, the battery cell moves to the position of the explosion-proof valve 12 under the impact of high-temperature and high-pressure gas. The bracket 142 and the boss 141 are both located between the cover plate 11 and the pole group 3, playing a supporting role. The sum of the height of the boss 141 protruding from the first surface of the cover plate 11 and the height of the bracket 142 is the height of the exhaust channel 15 between the pole group 3 and the cover plate 11.

[0046] In some embodiments, the boss 141 is configured as a prism, which facilitates processing.

[0047] In some embodiments, two groups of bosses 141 are provided, which are respectively located on both sides of the explosion-proof valve 12 .

[0048] Specifically, the number and position of the bosses 141 are arranged correspondingly to the number and position of the legs 1422 , and each leg 1422 is connected to one boss 141 .

[0049] In this embodiment, two legs 1422 are respectively provided on two opposite sides of a support plate 1421, that is, four legs 1422 are provided on a support plate 1421. Two groups of bosses 141 are provided on the first surface of the cover plate 11, two bosses 141 are provided in each group, and a total of four bosses 141 are provided, which are respectively provided on both sides of the explosion-proof valve 12 along the length direction of the cover plate 11. The legs 1422 are welded to the bosses 141 in correspondence with the positions of the four legs 1422 to achieve a fixed connection between the support 142 and the cover plate 11.

[0050] Furthermore, in some embodiments, the two groups of bosses 141 are symmetrically distributed on both sides of the explosion-proof valve 12 .

[0051] In some embodiments, the support plate 1421 is formed by stamping an aluminum plate. The support legs 1422 of the support plate 1421 are fixed to the surface of the boss 141 away from the cover plate 11 by welding, and the boss 141 and the support legs 142 are combined to form a protective structure of the explosion-proof valve 12.

[0052] In some embodiments, the support plate 1421 is provided with a window 1425, the inner wall of the window 1425 is connected with reinforcing ribs 1426, the reinforcing ribs 1426 are arranged at intervals or staggered, and the gaps between adjacent reinforcing ribs 1426 and / or between the reinforcing ribs 1426 and the inner wall of the window 1425 constitute exhaust holes 1423.

[0053] This arrangement can ensure the exhaust requirements while strengthening the structural strength of the support plate 1421, thereby ensuring that the support structure 14 can effectively and stably support the electrode group 3 after the plastic part 13 melts due to thermal runaway of the battery cell. Specifically, in this embodiment, the shape of the window 1425 is compatible with the shape of the explosion-proof valve 12, and the reinforcing ribs 1426 in the window 1425 are distributed in a "well" shape.

[0054] In some embodiments, the height of the exhaust channel 15 is H, 3 mm ≤ H ≤ 6 mm.

[0055] Specifically, the height by which the surface of the bracket 142 away from the cover plate 11 protrudes from the first surface of the cover plate 11 is the height of the exhaust passage 15 .

[0056] By controlling the height of the exhaust passage 15 within the range of 3 mm to 6 mm, high-temperature and high-pressure gas can be discharged more smoothly when thermal runaway occurs in the battery cell.

[0057] The following provides specific cases for testing, with a total of 19 groups tested, each group having 5 test cells, divided into embodiments and comparative examples, to verify the technical effects brought about by the technical solution of the present invention. The specific results are shown in Tables 1 and 2.

[0058] Specifically, the object of the test is a battery cell assembled by the battery cell cover plate assembly. Except for the variables in Table 1 and Table 2, the other factors and test conditions are the same. Table 1:

[0059]

[0060] Table 2:

[0061]

[0062] It can be seen from Table 1 and Table 2 that the design size of the support structure 14 has a great influence on the single-cell safety test results. The areas of S3, S2, and S1 need to satisfy S3 / A≥2.0, S1 / A≥1.08, and S2≥1.2S1 to ensure good support effect and smooth exhaust channel 15. At the same time, the exhaust area meets the cell capacity requirements, improves the pass rate of the cell safety test, and improves the safety performance of the cell.

[0063] According to an embodiment of the present invention, in a second aspect, a battery cell is further provided, comprising a shell 2, a pole group 3 and the battery cell cover assembly 1 in the above embodiment, wherein the shell 2 has an open end; the pole group 3 is disposed in the shell 2; the battery cell cover assembly 1 is disposed at the open end of the shell 2 to encapsulate the pole group 3 in the shell 2.

[0064] Because the battery cell includes the battery cell cover plate assembly 1, it has the same effect as the battery cell cover plate assembly 1, and will not be described in detail here.

[0065] According to an embodiment of the present invention, in a third aspect, a battery pack is further provided, comprising the battery cell in the above embodiment.

[0066] Since the battery pack includes battery cells and has the same effect as the battery cells, it will not be described in detail here.

[0067] Although the embodiments of the present invention have been described in conjunction with the accompanying drawings, those skilled in the art may make various modifications and variations without departing from the spirit and scope of the present invention, and such modifications and variations are all within the scope defined by the appended claims.

Claims

1. A battery cover assembly, characterized in that: include: A cover plate, wherein the cover plate is provided with an assembly hole, and the cover plate has a first surface facing the electrode group of the battery cell; An explosion-proof valve, the explosion-proof valve being arranged in the assembly hole; A plastic part, the plastic part is arranged on the first surface of the cover plate; A support structure, the support structure is arranged between the cover plate and the plastic part, the melting point of the support structure is higher than the melting point of the plastic part, and the support structure is suitable for supporting the plastic part between the electrode group and the cover plate after the plastic part melts due to the high temperature inside the battery cell, so as to form an exhaust channel connected to the explosion-proof valve; The support structure includes a bracket corresponding to the position of the explosion-proof valve, and the bracket is provided with a plurality of exhaust holes facing the explosion-proof valve. The area of ​​the explosion-proof valve is S1, in mm. 2 The total area of ​​the exhaust holes is S2, in mm 2 The effective supporting area of ​​the bracket for the electrode group of the battery cell is S3, in mm 2 , the capacity of the battery cell formed by the battery cell cover assembly is A, in Ah, and satisfies: S1 / A≥1.08, S3 / A ≥ 2.0, S2≥1.2S1.

2. The battery cover assembly according to claim 1, characterized in that: The bracket comprises a support plate arranged facing the explosion-proof valve and at least two support legs arranged at the edge of the support plate, and the exhaust hole is arranged on the support plate.

3. The battery cover assembly according to claim 2, characterized in that: Along the thickness direction of the cover plate, the exhaust hole is located within the projection range of the explosion-proof valve.

4. The battery cover assembly according to claim 2 or 3, characterized in that: The support structure further comprises a boss arranged on the first surface of the cover plate, the boss is arranged corresponding to the supporting feet, and each of the supporting feet is connected to one of the bosses.

5. The battery cover assembly according to claim 4, characterized in that: The bosses are arranged in two groups, and are respectively located on both sides of the explosion-proof valve.

6. The battery cover assembly according to claim 2 or 3, characterized in that: The support plate is provided with a window, the inner wall of the window is connected with reinforcing ribs, the reinforcing ribs are arranged at intervals or in a staggered manner, and the gaps between adjacent reinforcing ribs and / or between the reinforcing ribs and the inner wall of the window constitute the exhaust holes.

7. The battery cover assembly according to claim 2 or 3, characterized in that: An exhaust gap communicating with the exhaust channel is provided between the support foot, the support plate and the cover plate.

8. The battery cell cover plate assembly according to any one of claims 1 to 3, characterized in that: The height of the exhaust channel is H, 3mm≤H≤6mm.

9. A battery cell, characterized in that: include: a housing having an open end; A pole group, the pole group is arranged in the shell; The battery cell cover plate assembly according to any one of claims 1 to 8, wherein the battery cell cover plate assembly is arranged at the open end of the shell, and the electrode group is encapsulated in the shell.

10. A battery pack, characterized in that: Comprising the battery cell as claimed in claim 9.

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