Battery cover assembly, battery cell and battery pack

Abstract

The present invention relates to the field of battery technology, and discloses a battery cell cover plate assembly, a battery cell, and a battery pack. The battery cell cover plate assembly includes a cover plate, an explosion-proof valve, a plastic part, and a support structure. The cover plate is provided with an assembly hole; 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, and 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, and the support structure includes a support plate corresponding to the position of the explosion-proof valve, and the support plate is provided with a plurality of exhaust holes, and the proportional relationship between the area of ​​each part, and between the area of ​​each part and the capacity of the battery cell meets the preset conditions. In the present invention, when thermal runaway occurs in the battery cell, the support structure can maintain an exhaust channel connected to the explosion-proof valve between the pole group and the cover plate, thereby ensuring that the exhaust of the explosion-proof valve is not affected, thereby improving the safety performance of the battery cell.

Description

Technical Field

[0001] The present invention relates to the field of battery technology, 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 advantages such as 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. Their structure includes: a cell cover assembly, a shell, a pole group, an electrolyte, etc. The cell cover assembly integrates structural components such as pole posts, explosion-proof valves, and injection holes. 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 tabs on both sides of the pole group are fixed to the base of the pole posts on both sides of the cover by laser welding to achieve electrical connection. The length direction of the battery cell is mainly fixed by the lower plastic insulating material on the inside of the cover pressing against 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 gases when the battery experiences thermal runaway due to an internal short circuit, thereby improving battery safety performance.

[0004] When this type of battery cell reaches high temperatures, the lower plastic melts, rendering it ineffective in securing the electrode assembly. The high-temperature, high-pressure gas inside the cell then vents toward the explosion-proof valve. Driven by this high-temperature, high-pressure gas, the electrode assembly can move toward the valve, blocking it and blocking the exhaust passage. This affects the cell's pressure relief and reduces its safety. Summary of the Invention

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

[0006] In a first aspect, the present invention provides a cell cover assembly, comprising a cover, an explosion-proof valve, a plastic part, and a support structure. The cover is provided with an assembly hole, and has a first surface facing the electrode group of the cell; the explosion-proof valve is provided in the assembly hole; the plastic part is provided on the first surface of the cover; the support structure is provided between the cover and the plastic part, the melting point of the support structure is higher than the melting point of the plastic part, an exhaust channel connected to the explosion-proof valve is formed between the electrode group and the cover, the exhaust channel includes at least one exhaust port distributed circumferentially around the explosion-proof valve, and the total gas flow area of ​​the exhaust port is S1, in mm 2 The support structure includes a bracket corresponding to the explosion-proof valve position. The bracket is provided with a number of exhaust holes facing the explosion-proof valve. The total area of ​​the exhaust holes is S2, unit mm 2 The total projected area of ​​the support structure along the thickness direction of the cover is S, in mm. 2The capacity of the battery cell formed by the battery cell cover assembly is A, unit is Ah, and it satisfies: 1.6≤S1 / A≤2.2, 45%≤(S1+S2) / S≤58%.

[0007] Beneficial effect: The battery cover 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 cell, the plastic part melts and fails. At this time, the support structure has not melted, and the electrode 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 electrode group, and avoid the electrode group randomly moving with the high-temperature and high-pressure airflow to block the explosion-proof valve on the cover plate when the battery cell is thermally runaway, thereby affecting the exhaust effect of the explosion-proof valve. The support structure allows an exhaust channel connected to the explosion-proof valve to be maintained between the electrode group and the cover plate, 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 the proportional relationship between the areas of each part and the battery cell capacity, the strength of the support structure can be guaranteed, the support effect on the electrode group can be guaranteed, and the blocking ratio of the support structure to the explosion-proof valve can be reduced, 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 embodiment, 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 provided on the first surface of the cover plate, the boss is provided corresponding to the supporting legs, and each supporting leg is connected to a boss.

[0011] In an optional embodiment, two groups of bosses are provided, one located on each side 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 the gaps between the legs, the support plate and the cover plate form exhaust ports.

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

[0015] In a second aspect, the present invention also 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 effects: Since the battery pack includes battery cells, it has the same effects as the battery cells and will not be described in detail here. BRIEF DESCRIPTION OF THE DRAWINGS

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

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

[0021] Figure 2 This is a partial structural diagram of a battery cell cover 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 boss;

[0023] Figure 4 for Figure 2 A schematic structural diagram of the bracket in the battery cover assembly shown;

[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 Cross-sectional view along the middle line AA;

[0028] Figure 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 port; 1425. Window; 1426. Reinforcement rib; 2. Shell; 3. Pole group. DETAILED DESCRIPTION

[0031] To make the purpose, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying 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 making creative efforts shall fall within the scope of protection of the present invention.

[0032] At present, traditional battery cells, such as Figure 1 As shown, the battery cell includes a housing with two open ends. Two cell cover assemblies are located at the two open ends. The cell cover assemblies integrate a cover plate, a terminal post, an explosion-proof valve, and a plastic component. A pole group is located within the housing, with the plastic component positioned between the cover plate and the pole group to support and secure the pole group.

[0033] In the length direction of the battery cell, the pole 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. However, 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 pole group is left inside the battery cell. Due to the melting of the insulating protective material, the gap between the pole group and the cover and shell increases. At this time, the pole 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 pole 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] The following combination Figures 2 to 9 , describing embodiments of the present invention.

[0035] According to an embodiment of the present invention, in a first aspect, a 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 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, and the melting point of the support structure 14 is higher than the melting point of the plastic part 13. An exhaust channel connected to the explosion-proof valve 12 is formed between the pole group 3 and the cover plate 11, and the exhaust channel includes at least one exhaust port 1424 arranged circumferentially around the explosion-proof valve 12. The total gas flow area of ​​the exhaust port 1424 is S1, in mm. 2 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 facing the explosion-proof valve 12. The total area of ​​the exhaust holes 1423 is S2, in mm. 2 The total area of ​​the projection area of ​​the support structure 14 along the thickness direction of the cover plate 11 is S, in mm 2 The capacity of the battery cell formed by the battery cell cover assembly is A, unit is Ah, and it satisfies: 1.6≤S1 / A≤2.2, 45%≤(S1+S2) / S≤58%.

[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 electrode 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 electrode group 3, thereby preventing the electrode group 3 from randomly moving with the high-temperature and high-pressure airflow to block the explosion-proof valve 12 on the cover plate 11 when thermal runaway occurs in the battery cell, thereby affecting the exhaust effect of the explosion-proof valve 12. The support structure 14 ensures that an exhaust channel connected to the explosion-proof valve 12 is maintained between the electrode group 3 and the cover plate 11, 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, the following conditions are satisfied: 1.6≤S1 / A≤2.2, 45%≤(S1+S2) / S≤58%, thereby ensuring the strength of the support structure 14 and the supporting effect on the electrode group 3, while reducing the blocking ratio of the support structure 14 to the explosion-proof valve 12 and 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 edges of the support plate 1421 , and the exhaust hole 1423 is disposed on the support plate 1421 .

[0038] By providing the support legs 1422 on the edge of the support plate 1421 , the bracket 142 and the cover plate 11 can be stably connected via the support legs 1422 .

[0039] In some embodiments, the gaps between the legs 1422 , the support plate 1421 , and the cover plate 11 form an exhaust port 1424 .

[0040] Specifically, the use of legs 1422, compared to the technical solution of a long flange formed outward from the support plate 1421, allows the presence of an exhaust port 1424 between the support plate 1421 and the cover plate 11, further improving the flow of gas within the exhaust channel. At the same time, the material used for the legs 1422 can be reduced, reducing the overall weight of the cell cover plate assembly 1.

[0041] Specifically, the exhaust holes 1423 provide exhaust along the thickness direction of the cover plate 11, and the exhaust ports 1424 provide exhaust along the length or width direction of the cover plate 11. Figure 2 As shown. Figure 2 In the embodiment shown, four exhaust ports 1424 are formed between the support structure 14 and the cover plate 11 in a direction parallel to the cover plate 11. Figure 9 The shaded area is the cross-sectional area of ​​one exhaust port 1424 along the thickness direction of the cover plate 11, i.e., the gas flow area of ​​one exhaust port 1424. S1 is the sum of the gas flow cross-sectional areas of all exhaust ports 1424 around the explosion-proof valve 12.

[0042] When thermal runaway occurs inside the battery cell, the bracket 142 first supports the electrode group 3, so that an exhaust channel 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 port 1424 between the support leg 1422, the bracket 142 and the cover plate 11 are all connected to the exhaust channel, which can ensure the exhaust requirements.

[0043] 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 .

[0044] This arrangement can effectively prevent internal combustion materials 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.

[0045] 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 corresponding to the legs 1422 , and each leg 1422 is connected to a boss 141 .

[0046] The support structure 14 adopts a structure of a boss 141 and a bracket 142, which can facilitate the connection between the bracket 142 and the cover plate 11. Because the bracket 142 is connected to the boss 141, the bracket 142 and the boss 141 together constitute a protective structure for the explosion-proof valve 12. When the battery cell experiences thermal runaway and the plastic part 13 melts and fails, the battery cell moves toward the explosion-proof valve 12 under the impact of the high-temperature and high-pressure gas. The bracket 142 and the boss 141 are both located between the cover plate 11 and the electrode group 3, providing support. 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 between the electrode group 3 and the cover plate 11.

[0047] In this embodiment, the total area S of the projection area of ​​the support structure 14 along the thickness direction of the cover plate 11 is the total area of ​​the projection area of ​​the boss 141 and the bracket 142 along the thickness direction of the cover plate 11 .

[0048] In some embodiments, the boss 141 is configured as a prism, which facilitates processing.

[0049] In some embodiments, two groups of bosses 141 are provided, one located on each side of the explosion-proof valve 12 .

[0050] 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 .

[0051] In this embodiment, two legs 1422 are provided on opposite sides of a support plate 1421, i.e., 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, each group having two bosses, for a total of four bosses 141. These bosses 141 are positioned on either side of the explosion-proof valve 12 along the length of the cover plate 11. The legs 1422 are welded to the bosses 141, corresponding to the positions of the four legs 1422, to achieve a fixed connection between the support plate 142 and the cover plate 11.

[0052] Furthermore, in some embodiments, the two groups of bosses 141 are symmetrically distributed on both sides of the explosion-proof valve 12 .

[0053] In some embodiments, the support plate 1421 is stamped from an aluminum plate. The legs 1422 of the support plate 1421 are fixed to the surface of the boss 141 away from the cover plate 11 by welding. The boss 141 and the bracket 142 form a protective structure for the explosion-proof valve 12.

[0054] 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.

[0055] This arrangement ensures exhaust requirements while also strengthening the structural strength of the support plate, thereby ensuring that the support structure 14 effectively and stably supports the electrode assembly 3 after the plastic component 13 melts due to thermal runaway in the battery cell. Specifically, in this embodiment, the shape of the window 1425 matches the shape of the explosion-proof valve 12, and the reinforcing ribs 1426 within the window 1425 are arranged in a "well" shape.

[0056] In some embodiments, the height of the exhaust channel is H, 3 mm ≤ H ≤ 6 mm.

[0057] Specifically, the height of the side surface of the bracket 142 away from the cover plate 11 protruding from the first surface of the cover plate 11 is the height of the exhaust passage.

[0058] By controlling the height of the exhaust channel within the range of 3mm to 6mm, high-temperature and high-pressure gas can be discharged more smoothly when thermal runaway occurs in the battery cell.

[0059] The following provides specific cases for testing. A total of 12 groups were tested, with 5 test cells in each group, to verify the technical effects brought about by the technical solution of the present invention. The specific results are shown in Table 1.

[0060] Specifically, the test object is a battery cell assembled with the battery cell cover plate assembly. Except for the variables in Table 1, the other factors and test conditions are the same.

[0061] Table 1:

[0062]

[0063] It can be seen from Table 1 that the design size of the support structure 14 has a great influence on the safety test effect of a single battery cell. When S1 / A is less than 1.6 or (S1+S2) / S is less than 45%, the support structure 14 has an impact on the exhaust effect of the battery cell. When S1 / A is greater than 2.2 or (S1+S2) / S is greater than 58%, the overall strength of the support structure 14 is relatively weak, there is a risk of deformation, and the exhaust effect is also affected.

[0064] 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 arranged in the shell 2; the battery cell cover assembly 1 is arranged at the open end of the shell 2, and the pole group 3 is encapsulated in the shell 2.

[0065] Because the battery cell includes the battery cell cover plate assembly 1 and has the same effect as the battery cell cover plate assembly 1 , it will not be described in detail here.

[0066] 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.

[0067] Since the battery pack includes battery cells and has the same effect as the battery cells, it will not be described in detail here.

[0068] Although the embodiments of the present invention have been described with reference to 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. 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 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 being disposed on the first surface of the cover plate; A support structure, the support structure being provided between the cover plate and the plastic part, the melting point of the support structure being higher than the melting point of the plastic part, and an exhaust passage communicating with the explosion-proof valve being formed between the electrode group and the cover plate; The exhaust channel includes at least one exhaust port distributed circumferentially around the explosion-proof valve. The total gas flow area of ​​the exhaust port is S1, in mm. 2 , 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 total area of ​​the exhaust holes is S2, in mm. 2 The total area of ​​the projection area of ​​the support structure along the thickness direction of the cover plate is S, in mm 2 , the capacity of the battery cell formed by the battery cell cover assembly is A, unit Ah, meeting: 1.6≤S1 / A≤2.2, 45%≤(S1+S2) / S≤58%.

2. The battery cover assembly according to claim 1, characterized in that: The bracket includes a support plate arranged facing the explosion-proof valve and at least two supporting 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 includes a boss provided on the first surface of the cover plate, the boss is provided corresponding to the supporting legs, and each supporting leg is connected to one of the bosses.

5. The battery cover assembly according to claim 4, characterized in that: The bosses are provided 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: The gaps between the legs, the support plate and the cover plate form the exhaust port.

8. The battery cell cover 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 being 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: Including the battery cell according to claim 9.

Images