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 at least one 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 and located on the side of the anti-explosion valve, the melting point of the supporting structure is higher than that of the plastic part, and 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 to form an exhaust channel communicated with the anti-explosion valve; the size of the supporting structure, the capacity of the battery cell and the voltage meet a preset relational expression. According to the invention, the condition that the exhaust effect of the explosion-proof valve is influenced by the fact that the pole group randomly moves along with high-temperature and high-pressure airflow to shield the explosion-proof valve on the cover plate when the battery cell is subjected to thermal runaway can be avoided, the support structure enables an exhaust channel communicated with the explosion-proof valve to be kept between the pole group and the cover plate, the exhaust of the explosion-proof 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 cover plate assembly, including a cover plate, an explosion-proof valve, a plastic part and at least one supporting 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 supporting structure is provided between the cover plate and the plastic part and is located on the side of the explosion-proof valve, the melting point of the supporting structure is higher than the melting point of the plastic part, and an exhaust channel connected to the explosion-proof valve is formed between the pole group and the cover plate; along the length direction of the cover plate, the length occupied by the supporting structure is L1, in mm, along the width direction of the cover plate, the width occupied by the supporting structure is W1, in mm, the capacity of the battery cell formed by the battery cover plate assembly is C, in Ah, the voltage is U, in V, and it satisfies: (L1+W1) / CU≥0.030, 250Ah≤C≤1000Ah.

[0007] Beneficial effect: The battery cover plate assembly provided by the present invention is provided with an explosion-proof valve protection structure. By providing 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 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. By limiting the size of the support structure, the capacity of the battery cell, and the voltage to meet the preset relationship, it can not only ensure that the exhaust of the explosion-proof valve is not affected, but also effectively support and fix the pole group to ensure the exhaust effect of the battery cell.

[0008] In an optional implementation, the width of the cover plate is W, in mm, 0.65≤W1 / W≤0.80, and W-W1≥10 mm.

[0009] In an optional implementation, the length of the cover plate is L, in mm, and 0.20≤L1 / L≤0.30.

[0010] In an optional embodiment, the support structure includes at least two bosses provided on the first surface of the cover plate and a bracket connected to the bosses, and the bracket is connected to the cover plate via the bosses.

[0011] In an optional embodiment, the bracket includes a support plate and at least two supporting legs arranged on the edge of the support plate, the bosses are arranged corresponding to the supporting legs, and each supporting leg is connected to a boss respectively.

[0012] In an optional embodiment, two support structures are provided, and the two support structures are respectively arranged on both sides of the explosion-proof valve along the length direction of the cover plate.

[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, one of the boss and the leg is provided with an inserting protrusion, and the other is provided with an inserting hole that cooperates with the inserting protrusion. The boss and the leg are inserted through the cooperation of the inserting protrusion and the inserting hole, and are fixed by welding.

[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 for Figure 2 Schematic diagram of the structure of the middle 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; 143. Plug-in protrusion; 144. Plug-in hole; 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 inside the battery cell, 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 at least one supporting 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 and is located on the side of the explosion-proof valve 12, the melting point of the support structure 14 is higher than the melting point of the plastic part 13, and an exhaust channel 15 connected to the explosion-proof valve 12 is formed between the pole group 3 and the cover plate 11; along the length direction of the cover plate 11, the length occupied by the support structure 14 is L1, in mm, and along the width direction of the cover plate 11, the width occupied by the support structure 14 is W1, in mm, the capacity of the battery cell formed by the battery cell cover plate assembly is C, in Ah, and the voltage is U, in V, satisfying: (L1+W1) / CU≥0.030, 250Ah≤C≤1000Ah.

[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. By limiting the size of the support structure 14, the capacity of the battery cell, and the voltage to satisfy the preset relationship: (L1+W1) / CU≥0.030, 250Ah≤C≤1000Ah, it can ensure that the exhaust of the explosion-proof valve 12 is not affected, and at the same time can effectively support the fixed pole group 3 to ensure the exhaust effect of the battery cell.

[0037] In some embodiments, the width of the cover plate 11 is W, in mm, 0.65≤W1 / W≤0.80, and W-W1≥10 mm.

[0038] The ratio of the width W1 of the support structure 14 to the width W of the cover plate 11 is controlled within the range of 0.65 to 0.8, and the difference between the width W1 of the support structure 14 and the width W of the cover plate 11 is controlled within the range of not less than 10 mm. In this way, the support structure 14 can meet the requirements for supporting the electrode group 3 when thermal runaway occurs in the battery cell, and can also meet the assembly requirements of the battery cell, reducing the difficulty of assembly.

[0039] In some embodiments, the length of the cover plate 11 is L, in mm, and 0.20≤L1 / L≤0.30.

[0040] By controlling the ratio of the length L1 of the support structure 14 to the length L of the cover plate 11 within the range of 0.20 to 0.30, the support structure 14 can meet the requirement of supporting the electrode group 3 when thermal runaway occurs in the battery cell, and the exhaust effect of the explosion-proof valve 12 can be ensured.

[0041] In some embodiments, the support structure 14 includes at least two bosses 141 disposed on the first surface of the cover plate 11 and a bracket 142 connected to the bosses 141 , and the bracket 142 is connected to the cover plate 11 through the bosses 141 .

[0042] 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.

[0043] In some embodiments, the boss 141 is configured as a prism, which facilitates processing.

[0044] In some embodiments, the bracket 142 includes a support plate 1421 and at least two legs 1422 arranged on the edge of the support plate 1421. The number and position of the bosses 141 correspond to the number and position of the legs 1422, and each leg 1422 is connected to a boss 141 respectively.

[0045] By arranging the support legs 1422 on the edge of the support plate 1421 , the boss 141 and the bracket 142 are arranged correspondingly, so that one support leg 1422 is correspondingly connected to one boss 141 , and the bracket 142 and the cover plate 11 can be stably connected.

[0046] In this embodiment, two legs 1422 are respectively provided on two opposite sides of a support plate 1421, that is, one support plate 1421 is provided with four legs 1422. Four bosses 141 are provided in a group on the first surface of the cover plate 11, and the four bosses 141 are matched with the four legs 1422 in corresponding positions. The legs 1422 are welded to the bosses 141 to realize the fixed connection between the bracket 142 and the cover plate 11.

[0047] Specifically, along the thickness direction of the cover plate 11 , the projection of the bracket 142 is within the area formed by the projection of the boss 141 , and along the length direction of the cover plate 11 , the length occupied by the support structure 14 is the length occupied by the boss 141 .

[0048] 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.

[0049] In some embodiments, two support structures 14 are provided, and the two support structures 14 are respectively provided on both sides of the explosion-proof valve 12 along the length direction of the cover plate 11 .

[0050] In this embodiment, two support structures 14 are provided. Specifically, on the first surface of the cover plate 11, two groups of bosses 141 are provided, and two brackets 142 are provided. The position and number of the bosses 141 in each group correspond to the position and number of the legs 1422 of one bracket 142. The two brackets 142 are respectively welded and fixed to the two groups of bosses 141.

[0051] By providing two support structures 14, the support effect of the support structure 14 on the electrode group 3 can be improved when the battery cell has thermal runaway. Because the two support structures 14 are respectively provided on both sides of the explosion-proof valve 12, the two support structures 14 can provide stable support for the electrode group 3 along the length direction of the cover plate 11, ensuring the stability of the support structure 14 supporting the electrode group 3 after the plastic part 13 fails due to melting, maintaining the balance of the electrode group 3, and further ensuring the smoothness of the exhaust channel 15.

[0052] Furthermore, in some embodiments, the two support structures 14 are symmetrically distributed on both sides of the explosion-proof valve 12 .

[0053] In some embodiments, the support plate 1421 is provided with a plurality of exhaust holes 1423 ; and / or, an exhaust gap 1424 communicating with the exhaust channel 15 is provided between the support foot 1422 , the support plate 1421 and the cover plate 11 .

[0054] By providing a plurality of exhaust through holes 1423 on the support plate 1421 , it is possible to facilitate the flow of gas through the exhaust through holes 1423 , thereby improving the flow smoothness of the high-temperature and high-pressure gas in the exhaust channel 15 .

[0055] 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.

[0056] 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 through holes 1423 on the support plate 1421 and the exhaust gap 1424 in the height direction of the support foot 1422, the bracket 142 and the cover plate 11 are connected to the exhaust channel 15, which can ensure the exhaust requirements.

[0057] In some embodiments, one of the boss 141 and the leg 1422 is provided with an inserting protrusion 143, and the other is provided with an inserting hole 144 that cooperates with the inserting protrusion 143. The boss 141 and the leg 1422 are inserted through the matching of the inserting protrusion 143 and the inserting hole 144, and are fixed by welding.

[0058] In this embodiment, the boss 141 is provided with a plug-in protrusion 143, and the leg 1422 is provided with a plug-in hole 144. When the bracket 142 and the boss 141 are fixedly connected, the plug-in hole 144 of the leg 1422 is plugged and matched with the plug-in protrusion 143 of the boss 141, and then the boss 141 and the leg 1422 are welded and fixed. This arrangement can further improve the welding effect and ensure the overall structural strength of the support structure 14.

[0059] The plug hole 144 can be a through hole or a blind hole, depending on the actual situation.

[0060] The following provides specific cases for testing, with a total of 16 groups tested, each group having 6 test cells, to verify the technical effect brought by the technical solution of the present invention. The specific results are shown in Tables 1 and 2.

[0061] 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, the other factors and test conditions are the same.

[0062] Table 1:

[0063]

[0064] Table 2:

[0065]

[0066] According to Table 1 and Table 2, the size design of the support structure 14 has a great influence on the safety performance of the single cell. First, W1 must meet the assembly requirements. In addition, L1 and W1 must meet the requirements of supporting the electrode group 3, requiring (L1+W1) / CU≥0.030. At this time, the support structure 14 has a better effect in supporting the electrode group 3.

[0067] 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.

[0068] 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.

[0069] 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.

[0070] Since the battery pack includes battery cells and has the same effect as the battery cells, it will not be described in detail here.

[0071] 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; At least one supporting structure, the supporting structure is arranged between the cover plate and the plastic part and is located on the side of the explosion-proof valve, the melting point of the supporting structure is higher than the melting point of the plastic part, and an exhaust channel connected to the explosion-proof valve is formed between the electrode group and the cover plate; Along the length direction of the cover plate, the length occupied by the support structure is L1, in mm. Along the width direction of the cover plate, the width occupied by the support structure is W1, in mm. The capacity of the battery cell formed by the battery cell cover assembly is C, in Ah, and the voltage is U, in V. satisfy: (L1+W1) / CU≥0.030, 250Ah≤C≤1000Ah.

2. The battery cover assembly according to claim 1, characterized in that: The width of the cover plate is W, in mm, 0.65≤W1 / W≤0.80, and W-W1≥10 mm.

3. The battery cover assembly according to claim 2, characterized in that: The length of the cover plate is L, in mm, and 0.20≤L1 / L≤0.

30.

4. The battery cell cover plate assembly according to any one of claims 1 to 3, characterized in that: The supporting structure comprises at least two bosses arranged on the first surface of the cover plate and a bracket connected to the bosses, and the bracket is connected to the cover plate through the bosses.

5. The battery cover assembly according to claim 4, characterized in that: The bracket includes a support plate and at least two legs arranged on the edge of the support plate, the bosses are arranged corresponding to the legs, and each of the legs is connected to one of the bosses respectively.

6. The battery cell cover plate assembly according to any one of claims 1 to 3, characterized in that: The supporting structures are provided with two, and the two supporting structures are respectively arranged on both sides of the explosion-proof valve along the length direction of the cover plate.

7. The battery cover assembly according to claim 5, characterized in that: 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.

8. The battery cover assembly according to claim 5, characterized in that: One of the boss and the leg is provided with an inserting protrusion, and the other is provided with an inserting hole matched with the inserting protrusion. The boss and the leg are inserted through the matching of the inserting protrusion and the inserting hole, and are fixed by welding.

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.

Images