Explosion-proof valve, battery case and battery

Abstract

The application relates to the technical field of batteries and discloses an explosion-proof valve, a battery shell and a battery, which comprise a valve body, the valve body is provided with a notch in the thickness direction, the notch encloses an explosion area, the effective explosion area of the valve body is S, the circumference of the notch is c, the residual thickness of the valve body at the notch is h, the shearing strength of the valve body is tau, and the opening pressure of the valve body is p, and the value range of c / S is 0.375mm to 4.445mm. The value range of the ratio of the effective explosion area of the explosion-proof valve to the circumference of the notch is limited, so that the shell cannot collapse during the operation of the battery, the explosion-proof valve can be normally opened, the structural strength and the safety performance of the battery are considered, safety accidents are avoided, and the safe operation of the battery is ensured.

Description

Technical Field

[0001] This invention relates to the field of battery technology, specifically to explosion-proof valves, battery casings, and batteries. Background Technology

[0002] With the development of modern society and the increasing awareness of environmental protection, more and more devices are choosing batteries as their power source, especially electric vehicles, which require high-capacity, high-energy-density power batteries. Batteries are usually equipped with explosion-proof valves, which open in time to release gas and pressure in the event of thermal runaway of the battery cell. When the battery casing is made of high-strength materials (such as steel), the resulting battery can effectively improve thermal runaway conditions. However, precisely because steel is high-strength, the explosion-proof valves made from it are also high-strength, which can lead to the risk of the explosion-proof valves being difficult to open, or requiring extremely high pressure to open. Summary of the Invention

[0003] In view of this, the present invention provides an explosion-proof valve, a battery housing, and a battery to solve the problem that explosion-proof valves in the prior art are difficult to open or require extremely high pressure to open.

[0004] In a first aspect, the present invention provides an explosion-proof valve, comprising: a valve body, wherein a notch is formed on the valve body along its thickness direction, the notch enclosing a bursting zone; the effective bursting area of ​​the valve body is S, the perimeter of the notch is c, the residual thickness of the valve body corresponding to the notch is h, the shear strength of the valve body is τ, and the opening pressure of the valve body is p, satisfying the following conditions: but The value ranges from 0.375mm to 4.445mm.

[0005] Beneficial effects: By limiting the range of the ratio of the effective burst area of ​​the explosion-proof valve to the perimeter of the groove, the battery casing will not collapse during operation, and the explosion-proof valve can be opened normally. This balances the structural strength and safety performance of the battery, avoids safety accidents, and ensures the safe operation of the battery.

[0006] In one optional embodiment, the blasting zone has a rectangular structure, with two sides of length a and b, where a = m × b, and 1 ≤ m ≤ 4, satisfying the condition... but The value of b ranges from 0.93 mm to 17.78 mm.

[0007] Beneficial effects: When the blast zone is rectangular, by limiting the side length b of the rectangular structure, the battery casing will not collapse during operation, and the explosion-proof valve can be opened normally. This balances the structural strength and safety performance of the battery, avoids safety accidents, and ensures the safe operation of the battery.

[0008] In one optional implementation, the four corners of the rectangular structure are rounded, and the radius of the rounded corners is r, which satisfies r = k × b, where 0 < k < 0.5.

[0009] Beneficial effect: By rounding the four corners of the rectangular structure, stress concentration at the four corners of the rectangular structure is avoided, which makes the explosion-proof valve explode evenly.

[0010] In one optional embodiment, the blasting zone has a circular structure with a diameter of d, satisfying the following condition: but The value of d ranges from 1.5 mm to 17.78 mm.

[0011] Beneficial effects: When the blast zone is circular, by limiting the diameter d of the circular structure, the battery casing will not collapse during operation, and the explosion-proof valve can be opened normally. This balances the structural strength and safety performance of the battery, avoids safety accidents, and ensures the safe operation of the battery.

[0012] In one optional embodiment, the blasting zone has an elongated oval structure, comprising two spaced semicircular segments and a straight line segment connecting the two semicircular segments. The diameter of each semicircular segment is d, and the length of each straight line segment is l, where l = n × d, and 0 < n ≤ 4, satisfying... but The value of d ranges from 0.87 mm to 17.78 mm.

[0013] Beneficial effects: When the explosion zone has an elongated oval structure, by limiting the diameter d of the semicircular arc segment in the elongated oval structure, the battery casing will not collapse during operation, and the explosion-proof valve can be opened normally. This balances the structural strength and safety performance of the battery, avoids safety accidents, and ensures the safe operation of the battery.

[0014] In one optional embodiment, the shear strength τ ranges from 25 MPa to 50 MPa.

[0015] Beneficial effects: While ensuring the structural strength of the explosion-proof valve, production costs are controlled.

[0016] In one optional implementation, the opening pressure p ranges from 0.9 MPa to 2.0 MPa.

[0017] Beneficial effect: When gas accumulates inside the battery, causing excessive internal pressure, the explosion-proof valve opens to release gas and prevent the battery from exploding.

[0018] In one optional embodiment, the residual thickness h ranges from 0.03 mm to 0.08 mm.

[0019] Beneficial effects: While ensuring the connection strength between the blast zone and the rest of the valve body, it also ensures the effective blasting of the blast zone.

[0020] Secondly, the present invention also provides a battery casing including the aforementioned explosion-proof valve.

[0021] Thirdly, the present invention also provides a battery, including the battery casing described above. Attached Figure Description

[0022] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0023] Figure 1 This is a schematic diagram of the overall structure of the explosion-proof valve according to an embodiment of the present invention;

[0024] Figure 2 for Figure 1 A schematic cross-sectional view of the explosion-proof valve shown.

[0025] Figure 3 for Figure 2 A magnified view of the enlarged area of ​​the scoring on the explosion-proof valve shown.

[0026] Figure 4 This is a schematic diagram of the rectangular structure of the blasting zone in an embodiment of the present invention;

[0027] Figure 5 This is a schematic diagram of the structure of the blasting zone of an embodiment of the present invention, which is a rectangular structure with rounded corners;

[0028] Figure 6 This is a schematic diagram of the circular structure of the blasting zone in an embodiment of the present invention;

[0029] Figure 7 This is a schematic diagram of the blasting zone having an elongated oval structure according to an embodiment of the present invention;

[0030] Figure 8 This is a schematic diagram of the cover plate according to an embodiment of the present invention.

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

[0032] 1. Valve body; 101. Score. Detailed Implementation

[0033] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, 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, 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.

[0034] In the field of power battery technology, aluminum is currently the mainstream material for battery casings. The tensile strength of aluminum casings ranges from 100MPa to 250MPa, and the pressure resistance of an aluminum casing with a wall thickness of 0.5mm is approximately 1.3MPa to 1.6MPa. In ternary lithium-ion batteries, due to the relatively low pressure resistance of aluminum casings, the casing is prone to cracking, leading to battery fires and explosions. Using steel for the battery casing can effectively improve the structural strength of the battery. However, precisely because of the high strength of steel, the explosion-proof valves made from it also require high strength, which can lead to the risk of the explosion-proof valve being difficult to open, or requiring extremely high pressure to open, posing a safety hazard. In other words, steel-cased batteries with steel explosion-proof valves cannot simultaneously achieve both structural strength and safety performance.

[0035] The following is combined Figures 1 to 8 The following describes embodiments of the present invention.

[0036] According to an embodiment of the present invention, an explosion-proof valve is provided, including a valve body 1. A notch 101 is formed on the valve body 1 along its thickness direction, and the notch 101 encloses a bursting zone. The effective bursting area of ​​the valve body 1 is S, the perimeter of the notch 101 is c, the residual thickness of the valve body 1 corresponding to the notch 101 is h, the shear strength of the valve body 1 is τ, and the opening pressure of the valve body 1 is p, satisfying the following conditions: but The value ranges from 0.375mm to 4.445mm.

[0037] By limiting the range of the ratio of the effective burst area of ​​the explosion-proof valve to the perimeter of the notch 101, the battery casing will not collapse during operation, and the explosion-proof valve can be opened normally. This balances the structural strength and safety performance of the battery, avoids safety accidents, and ensures the safe operation of the battery.

[0038] It is worth noting that, such as Figure 3 As shown, a groove 101 is formed by etching downward along the thickness direction on the upper surface of the valve body 1. The portion of the valve body 1 after removing the groove 101 is the residual thickness.

[0039] In one embodiment, such as Figure 4 As shown, the blasting zone has a rectangular structure with two sides of length a and b, where a = m × b, and 1 ≤ m ≤ 4, satisfying the condition... but The value of b ranges from 0.93 mm to 17.78 mm.

[0040] When the blast zone is rectangular, by limiting the side length b of the rectangle, the battery casing will not collapse during operation, and the explosion-proof valve can be opened normally. This balances the structural strength and safety performance of the battery, avoids safety accidents, and ensures the safe operation of the battery.

[0041] Specifically, when h and τ are both constant values, the larger the value of b, the smaller the value of p. When the internal pressure of the battery reaches a relatively small value, the explosion-proof valve will open to release gas, increasing the production and use costs of the battery. Furthermore, the battery itself has a certain internal pressure, and when this internal pressure reaches the opening pressure, the explosion-proof valve will open, preventing the battery from operating safely. Conversely, when h and τ are both constant values, the smaller the value of b, the larger the value of p. The explosion-proof valve can only open to release gas when the internal pressure of the battery reaches a very large value. During the process of internal pressure accumulation, the casing is prone to cracking. Moreover, if the gas inside the battery cannot be released in time, there is a risk of battery explosion.

[0042] Specifically, when τ and p are both constant values, the larger the value of b, the larger the corresponding value of h. Excessive residual thickness makes it difficult for the explosion-proof valve to open, meaning the valve requires a higher opening pressure. The valve can only open to release gas when the internal pressure of the battery reaches a very high value. This internal pressure buildup can easily cause the casing to crack, and if the gas inside the battery cannot be released in time, there is a risk of battery explosion. Conversely, when τ and p are both constant values, the smaller the value of b, the smaller the corresponding value of h. Insufficient residual thickness makes the explosion-proof valve prone to cracking, compromising its structural strength.

[0043] Specifically, when h and p are both constant values, the larger the value of b, the larger the corresponding value of τ, and the greater the material strength of the explosion-proof valve. This requires the selection of better materials to make the battery casing, resulting in excessive production costs. When h and p are both constant values, the smaller the value of b, the smaller the corresponding value of τ, and the lower the material strength of the explosion-proof valve, resulting in insufficient structural strength of the explosion-proof valve itself.

[0044] In one embodiment, such as Figure 5 As shown, the four corners of the rectangular structure are rounded, and the radius of the rounded corners is r, which satisfies r = k × b, where 0 < k < 0.5.

[0045] By rounding the four corners of the rectangular structure, stress concentration at the corners is avoided, ensuring that the explosion-proof valve explodes evenly.

[0046] It is worth noting that, in order to avoid stress concentration, the four corners of a rectangular structure are usually rounded. The rounded corners have little impact on the blasting zone. Therefore, a rectangular structure with rounded corners can also satisfy the requirement that the value of b is in the range of 0.93mm to 17.78mm.

[0047] It should be noted that when k = 0, then r = 0, and the blasting zone is a standard rectangular structure (i.e., without rounded corners). When k = 0.5, then r = 0.5 × b, and the blasting zone is an oblong structure.

[0048] In one embodiment, such as Figure 6 As shown, the blasting zone has a circular structure with a diameter of d, satisfying the following condition: but The value of d ranges from 1.5 mm to 17.78 mm.

[0049] When the blast zone is circular, by limiting the diameter d of the circular structure, the battery casing will not collapse during operation, and the explosion-proof valve can be opened normally. This balances the structural strength and safety performance of the battery, avoids safety accidents, and ensures the safe operation of the battery.

[0050] In one embodiment, such as Figure 7 As shown, the blasting zone has an elongated oval structure, which includes two semicircular segments spaced apart and a straight line segment connecting the two semicircular segments. The diameter of the semicircular segments is d, and the length of the straight line segment is l, where l = n × d, and 0 < n ≤ 4, satisfying... but The value of d ranges from 0.87 mm to 17.78 mm.

[0051] When the blast zone has an elongated oval structure, by limiting the diameter d of the semicircular arc segment in the elongated oval structure, the battery casing will not collapse during operation, and the explosion-proof valve can be opened normally. This balances the structural strength and safety performance of the battery, avoids safety accidents, and ensures the safe operation of the battery.

[0052] It should be noted that when n=0, then l=0, and the blasting zone is a circular structure.

[0053] Specifically, when h and τ are both constant values, the larger the value of d, the smaller the value of p. When the internal pressure of the battery reaches a relatively small value, the explosion-proof valve will open to release gas, increasing the production and use costs of the battery. Furthermore, the battery itself has a certain internal pressure, and when this internal pressure reaches the opening pressure, the explosion-proof valve will open, preventing the battery from operating safely. Conversely, when h and τ are both constant values, the smaller the value of d, the larger the value of p. The explosion-proof valve can only open to release gas when the internal pressure of the battery reaches a very large value. During the process of internal pressure accumulation, the casing is prone to cracking. Moreover, if the gas inside the battery cannot be released in time, there is a risk of battery explosion.

[0054] Specifically, when τ and p are both constant values, the larger the value of d, the larger the corresponding value of h. Excessive residual thickness makes it difficult for the explosion-proof valve to open, meaning the valve requires a higher opening pressure. The valve can only open to release gas when the internal pressure of the battery reaches a very high value. This internal pressure buildup can easily cause the casing to crack, and if the gas inside the battery cannot be released in time, there is a risk of battery explosion. Conversely, when τ and p are both constant values, the smaller the value of d, the smaller the corresponding value of h. Insufficient residual thickness makes the explosion-proof valve prone to cracking, compromising its structural strength.

[0055] Specifically, when h and p are both constant values, the larger the value of d, the larger the corresponding value of τ, and the greater the material strength of the explosion-proof valve. This requires the selection of better materials to make the battery casing, resulting in excessive production costs. When h and p are both constant values, the smaller the value of d, the smaller the corresponding value of τ, and the lower the material strength of the explosion-proof valve, resulting in insufficient structural strength of the explosion-proof valve itself.

[0056] In one embodiment, the shear strength τ ranges from 25 MPa to 50 MPa. By controlling the value of the shear strength τ, production costs can be controlled while ensuring the structural strength of the explosion-proof valve.

[0057] Optionally, the shear strength τ can be 25MPa, 30MPa, 38MPa, 45MPa, 50MPa, etc.

[0058] In one embodiment, the opening pressure p ranges from 0.9 MPa to 2.0 MPa. When gas accumulates inside the battery, causing excessive internal pressure, the explosion-proof valve opens to release gas and prevent the battery from exploding.

[0059] Optionally, the opening pressure p can be 0.9MPa, 1.0MPa, 1.1MPa, 1.5MPa, 2.0MPa, etc.

[0060] In one embodiment, the residual thickness h ranges from 0.03 mm to 0.08 mm. This ensures the connection strength between the blast zone and the rest of the valve body 1 while guaranteeing the effective blasting of the blast zone.

[0061] Optionally, the residual thickness h can be 0.03 mm, 0.04 mm, 0.055 mm, 0.075 mm, 0.08 mm, etc.

[0062] The following explosion tests were conducted on different explosion-proof valves, and the experimental results are shown in Tables 1 and 2.

[0063] As shown in Table 1, in Examples 1 to 10, the values ​​of τ range from 25 MPa to 50 MPa, p range from 0.9 MPa to 2.0 MPa, and h range from 0.03 mm to 0.08 mm. Furthermore, for circular explosion-proof valves, the value of d ranges from 1.5 mm to 17.78 mm; for oblong explosion-proof valves, d ranges from 0.87 mm to 17.78 mm; and for rectangular explosion-proof valves, b ranges from 0.93 mm to 17.78 mm. Therefore, the explosion-proof valves in Examples 1 to 10 all pass the burst test.

[0064] As can be seen from Table 2, in Comparative Example 1 and Comparative Example 2, the value of d is too large, both greater than 17.78 mm. Therefore, the explosion zone area of ​​the explosion-proof valve is too large, and the explosion-proof valve can be opened with a small pressure during the test, resulting in low safety.

[0065] As can be seen from Table 2, in Comparative Examples 3 and 4, the value of h is too large, both greater than 0.08 mm. During the test, a large pressure is required to open the explosion-proof valve, resulting in low safety.

[0066] As can be seen from Table 2, in Comparative Examples 5 and 6, the value of h is too small, both less than 0.03 mm. During the test, the explosion-proof valve can be opened with a small pressure, resulting in low safety.

[0067] As can be seen from Table 2, in Comparative Examples 7 and 8, the value of τ is too large, both exceeding 50 MPa. During the test, a large pressure is required to open the explosion-proof valve, resulting in low safety.

[0068] As can be seen from Table 2, in Comparative Example 9 and Comparative Example 10, the value of τ is too small, both less than 25 MPa. During the test, the explosion-proof valve can be opened with a small pressure, resulting in low safety.

[0069] It is worth noting that the burst test involves placing the explosion-proof valve under test on a specific fixture, applying pressure, and causing the valve to crack at the scored area and burst open, indicating that it has opened. If the opening pressure of the explosion-proof valve is within the required range, it is considered OK; if the opening pressure exceeds the range, it is considered NG.

[0070] Table 1 Experimental Results of Examples

[0071]

[0072] Table 2 Comparative Experimental Results

[0073]

[0074] According to an embodiment of the present invention, another aspect provides a battery housing including the aforementioned explosion-proof valve.

[0075] In one embodiment, the battery casing further includes a housing and a cover plate, the housing having an opening, and the cover plate being connected to the housing and having a corresponding opening.

[0076] In one embodiment, such as Figure 8 As shown, the explosion-proof valve is installed on the cover plate, and there is one explosion-proof valve.

[0077] It should be noted that the cover plate may also be equipped with poles, upper plastic, riveting blocks, light aluminum sheets, lower plastic, sealing structures, etc.

[0078] Of course, in other alternative implementations, the explosion-proof valve is mounted on the cover plate, and there may be several explosion-proof valves.

[0079] In other alternative implementations, the explosion-proof valve may also be disposed on the housing, and one or more explosion-proof valves may be disposed.

[0080] According to an embodiment of the present invention, in another aspect, a battery is also provided, including the battery casing described above.

[0081] Although embodiments of the invention have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the invention, and such modifications and variations all fall within the scope defined by the appended claims.

Claims

1. An explosion-proof valve, characterized in that, include: A valve body has grooves formed along its thickness direction, which enclose a bursting zone. The effective bursting area of ​​the valve body is S, the perimeter of the grooves is c, the residual thickness of the valve body at the groove is h, the shear strength of the valve body is τ, and the opening pressure of the valve body is p, satisfying the following conditions: but The value ranges from 0.375mm to 4.445mm.

2. The explosion-proof valve according to claim 1, characterized in that, The blasting zone has a rectangular structure with two sides of length a and b, where a = m × b, and 1 ≤ m ≤ 4, satisfying the condition... but The value of b ranges from 0.93 mm to 17.78 mm.

3. The explosion-proof valve according to claim 2, characterized in that, The four corners of the rectangular structure are rounded, and the radius of the rounded corners is r, which satisfies r = k × b, where 0 < k < 0.

5.

4. The explosion-proof valve according to claim 1, characterized in that, The blasting zone has a circular structure with a diameter of d, satisfying the following conditions: but The value of d ranges from 1.5 mm to 17.78 mm.

5. The explosion-proof valve according to claim 1, characterized in that, The blasting zone has an elongated oval structure, comprising two spaced semicircular segments and a straight line segment connecting the two semicircular segments. The diameter of each semicircular segment is d, and the length of each straight line segment is l, where l = n × d, and 0 < n ≤ 4, satisfying the condition... but The value of d ranges from 0.87 mm to 17.78 mm.

6. The explosion-proof valve according to any one of claims 1 to 5, characterized in that, The shear strength τ ranges from 25 MPa to 50 MPa.

7. The explosion-proof valve according to any one of claims 1 to 5, characterized in that, The opening pressure p ranges from 0.9 MPa to 2.0 MPa.

8. The explosion-proof valve according to any one of claims 1 to 5, characterized in that, The residual thickness h ranges from 0.03 mm to 0.08 mm.

9. A battery casing, characterized in that, The explosion-proof valve includes any one of claims 1 to 8.

10. A battery, characterized in that, Includes the battery casing as described in claim 9.

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