Explosion-proof valve, battery housing, and battery

Abstract

Disclosed are an explosion-proof valve, a battery housing, and a battery. The explosion-proof valve comprises a valve body (1), wherein a notch (101) is formed in the valve body (1) in the thickness direction, and the notch (101) defines an explosion area; an effective explosion area of the valve body (1) is S, the perimeter of the notch (101) is c, the residual thickness of the corresponding valve body (1) at 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, which satisfy formula A: s=c×h×τ / p, that is, s / c=h×τ / p, and the value range of s / c is 0.375 mm to 4.445 mm. By defining the value range of the ratio of the effective explosion area of the explosion-proof valve to the perimeter of the notch (101), the housing does not collapse during operation of the battery, and the explosion-proof valve can be normally opened, thereby considering both the structural strength and safety performance of the battery, avoiding safety accidents, and ensuring safe operation of the battery.

Description

Explosion-proof valve, battery casing and battery

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to the Chinese patent application filed with the China Patent Office on December 11, 2023, with application number 202311702942.X and invention name “Explosion-proof valve, battery casing and battery”, the entire contents of which are incorporated by reference into this application. Technical Field

[0003] The present application relates to the field of battery technology, and in particular to an explosion-proof valve, a battery casing and a battery. Background Art

[0004] With the development of modern society and the enhancement of environmental awareness, more and more devices choose batteries as power sources, especially electric vehicles, which require large-capacity, high-energy-density power batteries. Batteries are usually equipped with explosion-proof valves, which open in time when the battery cell is in thermal runaway to relieve exhaust and pressure. When the battery casing is made of a high-strength material (such as steel), the resulting battery can effectively improve the thermal runaway situation. However, due to the high strength of steel, the resulting explosion-proof valve is also high in strength, which can easily lead to the risk of the explosion-proof valve being difficult to open or requiring extremely high pressure to open. Summary of the Invention

[0005] In view of this, the present application provides an explosion-proof valve, a battery housing and a battery to solve the problem in the prior art that the explosion-proof valve is difficult to open or requires extremely high pressure to open.

[0006] In a first aspect, the present application provides an explosion-proof valve, comprising: a valve body, wherein a notch is formed on the valve body along the thickness direction, wherein the notch encloses a bursting area; 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, the opening pressure of the valve body is p, and the valve body is 1. but The value range is 0.375mm to 4.445mm.

[0007] Beneficial effect: By limiting the range of the ratio of the effective blasting area of ​​the explosion-proof valve to the circumference of the notch, the battery shell will not collapse during operation and the explosion-proof valve can be opened normally, taking into account both the structural strength and safety performance of the battery, avoiding safety accidents and ensuring the safe operation of the battery.

[0008] In an optional embodiment, the blasting area is a rectangular structure, the lengths of the two sides of the rectangular structure are a and b respectively, and a=m×b, where 1≤m≤4, satisfying but The value range of b is 0.93mm to 17.78mm.

[0009] Beneficial effect: When the blasting area is a rectangular structure, by limiting the side length b of the rectangular structure, the battery shell will not collapse during operation, and the explosion-proof valve can be opened normally, taking into account the structural strength and safety performance of the battery, avoiding safety accidents and ensuring the safe operation of the battery.

[0010] In an optional embodiment, the four corners of the rectangular structure are rounded, and the radius of the rounded corners is r, satisfying r=k×b, where 0<k<0.5.

[0011] Beneficial effect: The four corners of the rectangular structure are set to be rounded, which avoids stress concentration at the four corners of the rectangular structure and makes the explosion-proof valve explode evenly.

[0012] In an optional embodiment, the blasting area is a circular structure with a diameter of d, satisfying but The value range of d is 1.5mm to 17.78mm.

[0013] Beneficial effect: When the explosion zone is a circular structure, by limiting the diameter d of the circular structure, the outer shell of the battery will not collapse during operation, and the explosion-proof valve can be opened normally, taking into account the structural strength and safety performance of the battery, avoiding safety accidents and ensuring the safe operation of the battery.

[0014] In an optional embodiment, the blasting area is an oblong structure, which includes two semicircular arc segments spaced apart and a straight line segment connecting the two semicircular arc segments. The diameter of the semicircular arc segment is d, the length of the straight line segment is l, and l = n × d, where 0 < n ≤ 4, satisfying but The value range of d is 0.87mm to 17.78mm.

[0015] Beneficial effect: When the blasting area is an oblong structure, by limiting the diameter d of the semicircular arc segment in the oblong structure, the outer shell of the battery will not collapse during operation, and the explosion-proof valve can be opened normally, taking into account the structural strength and safety performance of the battery, avoiding safety accidents and ensuring the safe operation of the battery.

[0016] In an optional embodiment, the shear strength τ ranges from 25 MPa to 50 MPa.

[0017] Beneficial effect: while ensuring the structural strength of the explosion-proof valve, the production cost is controlled.

[0018] In an optional embodiment, the opening pressure p ranges from 0.9 MPa to 2.0 MPa.

[0019] Beneficial effect: When gas accumulates inside the battery and causes the internal pressure of the battery to be too high, the explosion-proof valve opens to exhaust gas and avoid battery explosion.

[0020] In an optional embodiment, the residual thickness h ranges from 0.03 mm to 0.08 mm.

[0021] Beneficial effect: While ensuring the connection strength between the blasting zone and the rest of the valve body, the blasting zone is ensured to be effectively blasted.

[0022] In a second aspect, the present application also provides a battery housing comprising the above-mentioned explosion-proof valve.

[0023] In a third aspect, the present application also provides a battery, comprising the above-mentioned battery casing. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the specific implementation methods of the present application or the technical solutions in the prior art, the following is a brief introduction to the drawings required for use in the specific implementation methods or the description of the prior art. Obviously, the drawings described below are some implementation methods of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0025] FIG1 is a schematic diagram of the overall structure of an explosion-proof valve according to an embodiment of the present application;

[0026] FIG2 is a schematic cross-sectional view of the explosion-proof valve shown in FIG1 ;

[0027] FIG3 is an enlarged view of the notch of the explosion-proof valve shown in FIG2 ;

[0028] FIG4 is a schematic structural diagram of a blasting area in a rectangular structure according to an embodiment of the present application;

[0029] FIG5 is a schematic structural diagram of a blasting area in an embodiment of the present application in a rectangular structure with rounded corners;

[0030] FIG6 is a schematic structural diagram of a circular blasting zone according to an embodiment of the present application;

[0031] FIG7 is a schematic structural diagram of an embodiment of the present application in which the blasting zone is an oblong structure;

[0032] FIG8 is a schematic structural diagram of a cover plate according to an embodiment of the present application.

[0033] Description of the accompanying drawings: 1. valve body; 101. notch. DETAILED DESCRIPTION

[0034] To make the purpose, technical solutions, and advantages of the embodiments of the present application more clear, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without making creative efforts shall fall within the scope of protection of this application.

[0035] In the field of power battery technology, the current mainstream battery casing is made of aluminum. The tensile strength of the aluminum shell is between 100MPa and 250MPa, and the compressive strength of the aluminum shell with a wall thickness of 0.5mm is about 1.3MPa to 1.6MPa. In the ternary system, due to the low compressive strength of the aluminum shell, the shell is prone to rupture, causing the battery to catch fire and explode. When the battery casing is made of steel, the structural strength of the battery can be effectively improved. However, precisely because of the high strength of steel, the explosion-proof valve made is also high in strength, and there is a risk that the explosion-proof valve is difficult to open, or it requires extremely high pressure to open, posing a safety hazard. In other words, a steel-shell battery with a steel explosion-proof valve cannot take into account both structural strength and safety performance.

[0036] The following describes an embodiment of the present application in conjunction with Figures 1 to 8.

[0037] According to an embodiment of the present application, on the one hand, an explosion-proof valve is provided, comprising a valve body 1. A notch 101 is formed on the valve body 1 along the thickness direction, and the notch 101 encloses a bursting area. 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 but The value range is 0.375mm to 4.445mm.

[0038] By limiting the range of the ratio of the effective blasting area of ​​the explosion-proof valve to the circumference of the notch 101, the battery casing will not collapse during operation and the explosion-proof valve can be opened normally, taking into account both the structural strength and safety performance of the battery, avoiding safety accidents, and ensuring the safe operation of the battery.

[0039] It is worth noting that, as shown in FIG3 , a notch 101 is formed by etching downward along the thickness direction on the upper surface of the valve body 1 , and the portion of the valve body 1 excluding the notch 101 is the residual thickness.

[0040] In one embodiment, as shown in FIG4 , the blasting area is a rectangular structure, the lengths of the two sides of the rectangular structure are a and b respectively, and a=m×b, where 1≤m≤4, satisfying but The value range of b is 0.93mm to 17.78mm.

[0041] When the explosion zone is a rectangular structure, by limiting the side length b of the rectangular structure, the battery shell will not collapse during operation, and the explosion-proof valve can open normally, taking into account the structural strength and safety performance of the battery, avoiding safety accidents and ensuring the safe operation of the battery.

[0042] Specifically, when h and τ are both constants, the larger the value of b, the smaller the corresponding value of p. When the accumulated pressure inside the battery reaches a small value, the explosion-proof valve will open to exhaust, which increases the production and use costs of the battery. In addition, the battery itself has a certain internal pressure. When the internal pressure reaches the opening pressure, the explosion-proof valve will open and the battery cannot operate safely. When h and τ are both constants, the smaller the value of b, the larger the corresponding value of p. When the accumulated pressure inside the battery reaches a very high value, the explosion-proof valve can only open to exhaust. During the process of internal pressure accumulation of the battery, the shell is likely to burst. Moreover, when the gas inside the battery cannot be discharged in time, there is a risk of battery explosion.

[0043] Specifically, when τ and p are both constants, the larger the value of b, the larger the corresponding value of h, the larger the residual thickness, the more difficult it is to open the explosion-proof valve, that is, the greater the opening pressure required for the explosion-proof valve, the more pressure accumulated inside the battery reaches a very high value before the explosion-proof valve can open to exhaust. During the pressure accumulation process inside the battery, the outer shell may easily burst, and when the gas inside the battery cannot be discharged in time, there is a risk of battery explosion; when τ and p are both constants, the smaller the value of b, the smaller the corresponding value of h, the more small the residual thickness, the more likely it is that the explosion-proof valve will crack, and the structural strength of the explosion-proof valve itself cannot be guaranteed.

[0044] Specifically, when h and p are both constants, the larger the value of b, the larger the corresponding value of τ, and the greater the material strength of the explosion-proof valve, then a better material needs to be used to make the battery casing, resulting in excessively high production costs; when h and p are both constants, the smaller the value of b, the smaller the corresponding value of τ, the material strength of the explosion-proof valve is too low, and the structural strength of the explosion-proof valve itself is too low.

[0045] In one embodiment, as shown in FIG5 , the four corners of the rectangular structure are rounded, and the radius of the rounded corners is r, satisfying r=k×b, where 0<k<0.5.

[0046] The four corners of the rectangular structure are set to be rounded, which avoids stress concentration at the four corners of the rectangular structure and makes the explosion-proof valve explode evenly.

[0047] It is worth noting that in order to avoid stress concentration, the four corners of the rectangular structure are usually set to a rounded shape. The rounded shape has little effect on the blasting zone. Therefore, the rectangular structure with rounded corners can also meet the requirement that the value range of b is 0.93mm to 17.78mm.

[0048] It should be noted that when k=0, then r=0, and the blasting area is a standard rectangular structure (ie, without rounded corners). When k=0.5, then r=0.5×b, and the blasting area is an oblong structure.

[0049] In one embodiment, as shown in FIG6 , the blasting area is a circular structure with a diameter of d, satisfying but The value range of d is 1.5mm to 17.78mm.

[0050] When the explosion zone is a circular structure, by limiting the diameter d of the circular structure, the battery shell will not collapse during operation, and the explosion-proof valve can open normally, taking into account the structural strength and safety performance of the battery, avoiding safety accidents and ensuring the safe operation of the battery.

[0051] In one embodiment, as shown in FIG7 , the blasting area is an oblong structure, which includes two semicircular arc segments spaced apart and a straight line segment connecting the two semicircular arc segments. The diameter of the semicircular arc segment is d, the length of the straight line segment is l, and l=n×d, where 0<n≤4, satisfying but The value range of d is 0.87mm to 17.78mm.

[0052] When the blasting zone is an oblong structure, by limiting the diameter d of the semicircular arc segment in the oblong structure, the battery shell will not collapse during operation and the explosion-proof valve can open normally, taking into account the structural strength and safety performance of the battery, avoiding safety accidents and ensuring the safe operation of the battery.

[0053] It should be noted that when n=0, then l=0, and the blasting area is a circular structure.

[0054] Specifically, when h and τ are both constants, the larger the value of d, the smaller the corresponding value of p. When the accumulated pressure inside the battery reaches a small value, the explosion-proof valve will open to exhaust, which increases the production and use costs of the battery. In addition, the battery itself has a certain internal pressure. When the internal pressure reaches the opening pressure, the explosion-proof valve will open and the battery cannot operate safely. When h and τ are both constants, the smaller the value of d, the larger the corresponding value of p. When the accumulated pressure inside the battery reaches a very high value, the explosion-proof valve can only open to exhaust. During the process of internal pressure accumulation of the battery, the shell is likely to burst. Moreover, when the gas inside the battery cannot be discharged in time, there is a risk of battery explosion.

[0055] Specifically, when τ and p are both constants, the larger the value of d, the larger the corresponding value of h, the residual thickness is too large, and the explosion-proof valve is not easy to open. That is, the explosion-proof valve requires a larger opening pressure. When the accumulated pressure inside the battery reaches a very large value, the explosion-proof valve can open to exhaust. During the pressure accumulation process inside the battery, it is easy to cause the shell to burst. Moreover, when the gas inside the battery cannot be discharged in time, there is a risk of battery explosion. When τ and p are both constants, the smaller the value of d, the smaller the corresponding value of h, the residual thickness is too small, the explosion-proof valve is easy to crack, and the structural strength of the explosion-proof valve itself cannot be guaranteed.

[0056] Specifically, when h and p are both constants, the larger the value of d, the larger the corresponding value of τ, and the greater the material strength of the explosion-proof valve, then a better material needs to be used to make the battery casing, resulting in excessively high production costs; when h and p are both constants, the smaller the value of d, the smaller the corresponding value of τ, the material strength of the explosion-proof valve is too low, and the structural strength of the explosion-proof valve itself is too low.

[0057] In one embodiment, the shear strength τ ranges from 25 MPa to 50 MPa. By controlling the value of the shear strength τ, the production cost can be controlled while ensuring the structural strength of the explosion-proof valve.

[0058] Optionally, the value of the shear strength τ may be 25 MPa, 30 MPa, 38 MPa, 45 MPa, 50 MPa, etc.

[0059] In one embodiment, the opening pressure p ranges from 0.9 MPa to 2.0 MPa. When gas accumulates inside the battery and the internal pressure of the battery is too high, the explosion-proof valve is opened to exhaust gas and prevent the battery from exploding.

[0060] Optionally, the value of the opening pressure p may be 0.9 MPa, 1.0 MPa, 1.1 MPa, 1.5 MPa, 2.0 MPa, etc.

[0061] In one embodiment, the residual thickness h ranges from 0.03 mm to 0.08 mm, thereby ensuring the connection strength between the blasting zone and the rest of the valve body 1 and ensuring effective blasting of the blasting zone.

[0062] Optionally, the residual thickness h may be 0.03 mm, 0.04 mm, 0.055 mm, 0.075 mm, 0.08 mm, etc.

[0063] The following explosion tests are carried out on different explosion-proof valves. The experimental results are shown in Tables 1 and 2.

[0064] As can be seen from Table 1, in Examples 1 to 10, the value of τ is in the range of 25 MPa to 50 MPa, the value of p is in the range of 0.9 MPa to 2.0 MPa, the value of h is in the range of 0.03 mm to 0.08 mm, and for the circular explosion-proof valve, the value of d is in the range of 1.5 mm to 17.78 mm, for the oblong explosion-proof valve, the value of d is in the range of 0.87 mm to 17.78 mm, and for the rectangular explosion-proof valve, the value of b is in the range of 0.93 mm to 17.78 mm. Therefore, the explosion-proof valves of Examples 1 to 10 can all pass the burst test.

[0065] As can be seen from Table 2, in Comparative Examples 1 and 2, the value of d is too large, both greater than 17.78 mm. Therefore, the explosion zone of the explosion-proof valve is too large. During the test, the explosion-proof valve can be opened by a relatively small pressure, resulting in low safety.

[0066] It can be seen from Table 2 that 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.

[0067] It can be seen from Table 2 that 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 by a relatively small pressure, resulting in low safety.

[0068] It can be seen from Table 2 that in Comparative Examples 7 and 8, the values ​​of τ are too large, both greater than 50 MPa. During the test, a large pressure is required to open the explosion-proof valve, resulting in low safety.

[0069] It can be seen from Table 2 that in Comparative Examples 9 and 10, the values ​​of τ are too small, both less than 25 MPa. During the test, the explosion-proof valve can be opened by a relatively small pressure, resulting in low safety.

[0070] It's worth noting that a burst test involves placing the explosion-proof valve under test on a specific fixture and applying pressure. This occurs when the notched portion of the valve cracks and the burst zone flips open, indicating the valve is open. If the valve's opening pressure is within the specified range, it's considered OK. If it exceeds the specified range, it's considered NG.

[0071] Table 1 Experimental results of the embodiment

[0072] Table 2 Comparative Example Experimental Results

[0073] According to an embodiment of the present application, on the other hand, a battery housing is provided, comprising the above-mentioned explosion-proof valve.

[0074] In one embodiment, the battery housing further includes a shell and a cover plate, the shell is provided with an opening, and the cover plate is connected to the shell and is provided corresponding to the opening.

[0075] In one embodiment, as shown in FIG8 , an explosion-proof valve is provided on the cover plate, and one explosion-proof valve is provided.

[0076] It should be noted that the cover plate may also be provided with a pole, an upper plastic, a riveted block, a plain aluminum sheet, a lower plastic, a sealing structure, and the like.

[0077] Of course, in other alternative embodiments, the explosion-proof valve is provided on the cover plate, and there may be several explosion-proof valves.

[0078] In other alternative embodiments, the explosion-proof valve may also be provided on the housing, with one or more explosion-proof valves being provided.

[0079] According to an embodiment of the present application, on another aspect, a battery is provided, comprising the above-mentioned battery casing.

[0080] Although the embodiments of the present application 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 application, and such modifications and variations shall fall within the scope defined by the appended claims.

Claims

1. An explosion-proof valve, characterized in that: include: A valve body, wherein a notch is formed on the valve body along the thickness direction, and the notch encloses a bursting area; 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 but The value range is 0.375mm to 4.445mm.

2. The explosion-proof valve according to claim 1, characterized in that: The blasting area is a rectangular structure, the lengths of the two sides of the rectangular structure are a and b respectively, and a = m × b, where 1≤m≤4, satisfying but The value range of b is 0.93mm to 17.78mm.

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 corner is r, satisfying r=k×b, wherein 0<k<0.

5.

4. The explosion-proof valve according to claim 1, characterized in that: The blasting area is a circular structure, the diameter of the circular structure is d, and satisfies but The value range of d is 1.5mm to 17.78mm.

5. The explosion-proof valve according to claim 1, characterized in that: The blasting area is in an oblong structure, and the oblong structure includes two semicircular arc segments arranged at intervals and a straight line segment connected between the two semicircular arc segments, the diameter of the semicircular arc segment is d, the length of the straight line segment is l, and l=n×d, wherein 0<n≤4, satisfying but The value range of d is 0.87mm to 17.78mm.

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 has a value range of 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 comprises the explosion-proof valve according to any one of claims 1 to 8.

10. A battery, characterized in that: The battery casing comprises the battery casing as claimed in claim 9.

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