Explosion-proof valve, cover plate assembly, battery cell, battery pack and electrical system

Abstract

An explosion-proof valve (100), a cover plate assembly, a battery cell, a battery pack and an electrical system. The explosion-proof valve (100) comprises a main body (1), a rupture disc (2) and a temperature-sensitive film (3). The main body (1) is provided with a pressure relief hole (11) passing through same in the thickness direction. The rupture disc (2) and the temperature-sensitive film (3) are connected to the main body (1) and cover the pressure relief hole (11). The temperature-sensitive film (3) is made of plastic, such that the cracking critical pressure value of the temperature-sensitive film (3) is inversely proportional to the temperature of the explosion-proof valve (100), the thickness of the temperature-sensitive film (3) being A, and 0.05mm≤A≤0.5mm. The present invention provides the temperature-sensitive film (3) in the explosion-proof valve (100) and limits the size of the temperature-sensitive film (3), and therefore under the limitation of the size, when the battery cell is in a normal working condition, the temperature-sensitive film (3) together with the rupture disc (2) can cover the pressure relief hole (11) of the main body (1), thereby improving the opening pressure of the pressure relief hole (11) and reducing the risk of the pressure relief hole (11) being mistakenly opened; and when the battery cell is out of control, the high temperature achieved after the battery cell is out of control enables the temperature-sensitive film (3) to be quickly softened, so as to reduce the opening pressure of the explosion-proof valve (100), thus achieving the purpose of quickly opening the valve.

Description

Explosion-proof valves, cover assemblies, battery cells, battery packs, and power systems

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to the Chinese patent application filed with the China Patent Office on February 22, 2024, with application number 202410199341X and application name “Explosion-proof valve, cover assembly, battery cell, battery pack and power system”, the entire contents of which are incorporated by reference into this application. Technical Field

[0003] The present application relates to the technical field of battery explosion-proof technology, and more specifically, to an explosion-proof valve, a cover assembly, a battery cell, a battery pack, and an electrical system. Background Art

[0004] A battery cell is a device that converts chemical energy into electrical energy and is widely used in new energy vehicles, energy storage power stations, and other fields. The battery cell has an explosion-proof valve. When the pressure inside the battery cell exceeds the preset opening pressure of the valve, the valve automatically opens, releasing the pressure inside the battery cell and ensuring the safe operation of the battery cell.

[0005] Given the operating characteristics of explosion-proof valves, designers typically aim for a higher opening pressure under normal operating conditions to prevent accidental opening. However, in the event of battery loss, the valve can be designed with a lower opening pressure to increase its opening speed and ensure the safety of the battery cell and surrounding cells.

[0006] However, in the related art, regardless of whether the battery cell is out of control or not, the opening pressure of the explosion-proof valve can only be maintained at a constant value, and the explosion-proof valve has poor adaptability to different working conditions of the battery cell.

[0007] Summary of the Invention

[0008] The purpose of this application is to provide an explosion-proof valve, a cover plate assembly, a battery cell, a battery pack and an electrical system, aiming to solve the problem in related technologies that the explosion-proof valve has poor adaptability to various working conditions of the battery cell.

[0009] In a first aspect, the present application discloses an explosion-proof valve, comprising a main body, an explosion-proof disc, and a temperature-sensitive membrane. The main body is provided with a pressure relief hole extending through its thickness. The explosion-proof disc and the temperature-sensitive membrane are connected to the main body and cover the pressure relief hole. The temperature-sensitive membrane is made of plastic so that the critical rupture pressure of the temperature-sensitive membrane is inversely proportional to the temperature of the explosion-proof valve.

[0010] Wherein, the thickness of the temperature-sensitive film is A, 0.05mm≤A≤0.5mm.

[0011] In a possible implementation, the temperature-sensitive film includes at least two temperature-sensitive layers stacked sequentially along the axis of the pressure relief hole.

[0012] In a possible implementation, the plastic includes at least one of polypropylene, polyethylene, and polyethylene terephthalate.

[0013] In a possible implementation, the plastic used in each temperature-sensing layer is set to be the same, and the thickness of the temperature-sensing film is A, 0.12 mm ≤ A ≤ 0.18 mm.

[0014] In a possible implementation, the thickness of each temperature-sensitive layer is B, and 0.04 mm ≤ B ≤ 0.06 mm.

[0015] In a possible implementation, the temperature sensing layer includes a first temperature sensing layer, a second temperature sensing layer, and a third temperature sensing layer, and the third temperature sensing layer is connected to the main body;

[0016] The first temperature-sensing layer and the third temperature-sensing layer are made of polypropylene, and the second temperature-sensing layer is made of polyethylene terephthalate.

[0017] The thickness of the temperature-sensitive film is A, 0.07 mm ≤ A ≤ 0.13 mm.

[0018] In a possible implementation, the first temperature sensing layer, the second temperature sensing layer, and the third temperature sensing layer satisfy at least one of the following relationships: 0.02 mm ≤ C ≤ 0.04 mm, 0.03 mm ≤ D ≤ 0.05 mm, and 0.02 mm ≤ E ≤ 0.04 mm;

[0019] Wherein, C is the thickness of the first temperature-sensitive layer;

[0020] D is the thickness of the second temperature-sensitive layer;

[0021] E is the thickness of the third temperature-sensitive layer.

[0022] In a possible implementation, a notch is provided on the side of the explosion-proof disk facing the temperature-sensitive membrane, and an outer edge of the notch forms a pressure relief area.

[0023] Along the length direction of the explosion-proof valve, the length of the temperature-sensitive membrane is F, the length of the pressure relief area is G, and 1mm≤FG≤1.5mm.

[0024] In a possible implementation, a notched groove is provided on the side of the explosion-proof disk facing the temperature-sensitive membrane;

[0025] The minimum distance from the bottom of the notched groove to the side of the explosion-proof disk facing away from the temperature-sensitive membrane is H, and 0.02 mm ≤ H ≤ 0.1 mm.

[0026] In a possible implementation, the explosion-proof disk has a thickness J, 0.2 mm ≤ J ≤ 1 mm.

[0027] In a possible implementation, the main body includes a first surface and a second surface that are oppositely disposed, and the pressure relief hole passes through the first surface and the second surface;

[0028] The explosion-proof plate is arranged on the first surface, and the temperature-sensitive membrane is arranged on the second surface.

[0029] In a possible implementation, the depth of the pressure relief hole is K, and 0.5 mm ≤ K ≤ 2 mm.

[0030] In a second aspect, the present application discloses a cover plate assembly, the cover plate assembly including an explosion-proof valve, the explosion-proof valve including a main body, an explosion-proof disc, and a temperature-sensitive membrane. The main body is provided with a pressure relief hole extending through the thickness thereof; the explosion-proof disc and the temperature-sensitive membrane are connected to the main body and cover the pressure relief hole; the temperature-sensitive membrane is made of plastic so that the critical pressure value of the rupture of the temperature-sensitive membrane is inversely proportional to the temperature of the explosion-proof valve;

[0031] Wherein, the thickness of the temperature-sensitive film is A, 0.05mm≤A≤0.5mm.

[0032] In a third aspect, the present application discloses a battery cell, comprising a cover assembly, the cover assembly comprising an explosion-proof valve, the explosion-proof valve comprising a main body, an explosion-proof disc, and a temperature-sensitive membrane, the main body being provided with a pressure relief hole extending through the thickness thereof; the explosion-proof disc and the temperature-sensitive membrane being connected to the main body and covering the pressure relief hole; the temperature-sensitive membrane being made of plastic so that the critical rupture pressure of the temperature-sensitive membrane is inversely proportional to the temperature of the explosion-proof valve;

[0033] Wherein, the thickness of the temperature-sensitive film is A, 0.05mm≤A≤0.5mm.

[0034] In a fourth aspect, the present application discloses a battery pack, comprising a battery cell, the battery cell comprising a cover assembly, the cover assembly comprising an explosion-proof valve, the explosion-proof valve comprising a main body, an explosion-proof disc, and a temperature-sensitive membrane, the main body being provided with a pressure relief hole extending through the main body along its thickness; the explosion-proof disc and the temperature-sensitive membrane being connected to the main body and covering the pressure relief hole; the temperature-sensitive membrane being made of plastic so that a critical rupture pressure of the temperature-sensitive membrane is inversely proportional to the temperature of the explosion-proof valve;

[0035] Wherein, the thickness of the temperature-sensitive film is A, 0.05mm≤A≤0.5mm.

[0036] In a fifth aspect, the present application discloses an electricity system, comprising a battery pack, the battery pack comprising a cover assembly, the cover assembly comprising an explosion-proof valve, the explosion-proof valve comprising a main body, an explosion-proof disc, and a temperature-sensitive membrane, the main body being provided with a pressure relief hole extending through the main body along its thickness; the explosion-proof disc and the temperature-sensitive membrane being connected to the main body and covering the pressure relief hole; the temperature-sensitive membrane being made of plastic so that the critical rupture pressure of the temperature-sensitive membrane is inversely proportional to the temperature of the explosion-proof valve;

[0037] Wherein, the thickness of the temperature-sensitive film is A, 0.05mm≤A≤0.5mm.

[0038] In combination with the above technical solutions, this application sets a temperature-sensitive membrane in the explosion-proof valve and limits the size of the temperature-sensitive membrane. Under this size limit, when the battery cell is in normal operating conditions, the temperature-sensitive membrane and the explosion-proof disc can cover the main pressure relief hole together, thereby increasing the opening pressure of the pressure relief hole and reducing the risk of the pressure relief hole being accidentally opened. When the battery cell loses control, the high temperature of the battery cell after the loss of control will cause the temperature-sensitive membrane to soften rapidly, thereby reducing the critical rupture pressure of the temperature-sensitive membrane and the opening pressure of the explosion-proof valve, thereby achieving the purpose of rapid valve opening. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the background technology, the drawings required for use in the embodiments of the present application or the background technology will be described below.

[0040] FIG1 is a schematic structural diagram of an explosion-proof valve according to an embodiment of the present invention;

[0041] FIG2 is a cross-sectional view of an embodiment of the assembly of the explosion-proof disk, the temperature-sensitive membrane, and the main body in FIG1 ;

[0042] FIG3 is a schematic structural diagram of the main body in FIG1 ;

[0043] FIG4 is a front view of the explosion-proof disk and the temperature-sensitive membrane;

[0044] FIG5 is a cross-sectional view of FIG4;

[0045] FIG6 is an enlarged view of FIG5 at position S;

[0046] FIG7 is a schematic structural diagram of the temperature-sensitive membrane in FIG1 ;

[0047] FIG8 is a cross-sectional view of another embodiment of the assembly of the explosion-proof disk, the temperature-sensitive membrane, and the main body in FIG1 .

[0048] Description of reference numerals:

[0049] 100-explosion-proof valve;

[0050] 1-main body, 11-pressure relief hole, 12-installation slot;

[0051] 2-burst disk, 21-scored groove, 211-pressure relief area;

[0052] 3 - Temperature-sensitive film, 31 - Temperature-sensitive layer, 31a - First temperature-sensitive layer, 31b - Second temperature-sensitive layer, 31c - Third temperature-sensitive layer. DETAILED DESCRIPTION

[0053] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments of this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0054] It should be noted that when a component is referred to as being "fixed to" another component, it may be directly on the other component or there may be an intermediate component. When a component is referred to as being "connected to" another component, it may be directly connected to the other component or there may be an intermediate component.

[0055] Unless otherwise defined, all technical and scientific terms used in this application have the same meanings as those commonly understood by those skilled in the art to which this application belongs. The terms used in this specification are for the purpose of describing specific embodiments only and are not intended to limit this application. The term "and / or" as used in this application includes any and all combinations of one or more of the relevant listed items.

[0056] The following describes some embodiments of the present application in detail with reference to the accompanying drawings. In the absence of conflict, the following embodiments and features therein may be combined with each other.

[0057] This application proposes an electricity system that can be applied to vehicles, industrial production lines, and household appliances, and this application does not impose any restrictions on this. Taking vehicles as an example, when the electricity system is applied to vehicles, the vehicles can be electric vehicles, fuel vehicles, or hybrid vehicles, and this application does not impose any restrictions on this. The vehicles can be cars, off-road vehicles, trucks, or forklifts, and this application does not impose any restrictions on this.

[0058] The power system includes a battery pack and power-consuming devices. The power-consuming devices are mounted on the vehicle body. The power-consuming devices may be the vehicle's engine, the vehicle's dashboard, or even the vehicle's doors or windows, though this application does not impose any restrictions thereon. The battery pack is located within the vehicle's mounting cavity and is connected to the power-consuming devices. The battery pack is used to store electrical energy and release it when the power-consuming devices need it, thereby maintaining normal operation of the power-consuming devices.

[0059] A battery pack consists of a housing and cells. The housing, as the main body of the pack, supports and connects the various components. The housing houses the cells, which are the energy source of the pack and are used to store and release electrical energy.

[0060] The battery cell consists of a housing, a cover assembly, and a core. The housing forms a chamber with an opening on one side, which contains an electrolyte. The core is housed in the chamber and reacts with the electrolyte inside, storing and releasing electrical energy. The cover assembly covers the opening of the chamber and seals it to prevent dust and impurities from entering, maintaining stable operation of the cell inside.

[0061] The cover plate assembly includes a cover plate and an explosion-proof valve, and the cover plate is arranged on the opening of the accommodating chamber. The explosion-proof valve is arranged on the cover plate, and the explosion-proof valve is used to be opened when the pressure in the accommodating chamber exceeds the preset opening pressure, thereby releasing the air pressure in the accommodating chamber, thereby ensuring the safe operation of the battery cell and its surrounding battery cells. During daily use of the explosion-proof valve, designers usually hope that the pressure of the explosion-proof valve can change with the working conditions of the battery cell, that is, when the battery cell is in normal working conditions, the explosion-proof valve can have a higher opening pressure to ensure that the explosion-proof valve will not be opened by mistake. When the battery is out of control, the explosion-proof valve can have a smaller opening pressure to increase the opening speed of the explosion-proof valve and ensure the safety of the battery cell.

[0062] However, in the related art, regardless of whether the battery cell is out of control or not, the opening pressure of the explosion-proof valve can only be maintained at a constant value, and the explosion-proof valve has poor adaptability to different working conditions of the battery cell.

[0063] To solve the above problems, please refer to Figure 1. In the present application, the explosion-proof valve 100 includes a main body 1, an explosion-proof disc 2 and a temperature-sensitive membrane 3. The main body 1 is provided with a pressure relief hole 11 running through it in the thickness direction. The explosion-proof disc 2 is connected to the main body 1, and the explosion-proof disc 2 covers the pressure relief hole 11. The temperature-sensitive membrane 3 is connected to the main body 1, and the temperature-sensitive membrane 3 covers the pressure relief hole 11. The temperature-sensitive membrane 3 is made of plastic so that the critical rupture pressure value of the temperature-sensitive membrane 3 is inversely proportional to the temperature of the explosion-proof valve 100. The thickness of the temperature-sensitive membrane is A, 0.05mm≤A≤0.5mm. The technical solution of the present application is to set a temperature-sensitive membrane 3 in the explosion-proof valve 100 and limit the size of the temperature-sensitive membrane 3. Under the size limit, when the battery cell is in normal working conditions, the temperature-sensitive membrane 3 and the explosion-proof disc 2 jointly cover the pressure relief hole 11 of the main body 1, thereby increasing the opening pressure of the pressure relief hole 11 and reducing the risk of the pressure relief hole 11 being opened by mistake. When the battery cell is out of control, the high temperature after the out-of-control battery cell will cause the temperature sensitive membrane 3 to be softened quickly, thereby reducing the critical rupture pressure value of the temperature sensitive membrane 3 and the opening pressure of the explosion-proof valve 100, thereby achieving the purpose of rapid valve opening.

[0064] Hereinafter, various components of the explosion-proof valve 100 provided in the present application will be described in detail with reference to the accompanying drawings.

[0065] Please refer to Figures 2 and 3. The explosion-proof valve 100 provided in the present application includes a main body 1. The main body 1 serves as the main body of the explosion-proof valve 100 and is used to support and connect the various components of the explosion-proof valve 100. The main body 1 is connected to the cover plate. The main body 1 and the cover plate can be formed as one piece, or they can be formed separately and then connected to each other. In the embodiment of the present application, the main body 1 and the cover plate are formed as one piece. The main body 1 can serve as the main structure of the explosion-proof valve 100 and is used to support and connect the explosion-proof disc 2 and the temperature-sensitive membrane 3. It can also serve as the main structure of the cover plate assembly to cover the opening of the accommodating cavity and support and connect other components provided on the cover plate assembly, such as poles and spacers.

[0066] The main body 1 is provided with a pressure relief hole 11, which communicates with the accommodating chamber. The explosion-proof disk 2 is connected to the main body 1. The explosion-proof disk 2 and the main body 1 can be connected by bonding, heat fusion, or welding, which is not limited in this application. The explosion-proof disk 2 is made of metal, which can be aluminum, iron, or steel, which is not limited in this application.

[0067] In one possible embodiment of the present application, the explosion-proof disc 2 is welded to the main body 1. A fixed portion is formed on the outer edge of the explosion-proof disc 2 by welding, and the explosion-proof disc 2 is connected to the main body 1 via the fixed portion. During the welding process of the explosion-proof disc 2 to the main body 1, weld veins will form around the fixed portion. In this embodiment, the outer edge of the orthographic projection of the fixed portion is located within the orthographic projection of the temperature-sensitive membrane 3. In this way, the weld veins around the fixed portion are shielded by the temperature-sensitive membrane 3, thereby preventing welding foreign matter from falling into the accommodating cavity when the explosion-proof disc 2 is welded to the main body 1, thereby affecting the normal use of the electrode core in the accommodating cavity.

[0068] Referring to Figures 1 and 4 , the explosion-proof disc 2 is positioned over the pressure relief hole 11. The explosion-proof disc 2 is positioned over the pressure relief hole 11 to influence the opening pressure of the explosion-proof valve after a battery cell loses control. It is understood that the total opening pressure of the explosion-proof valve 100 should be neither too low nor too high. If the total opening pressure of the explosion-proof valve 100 is too low, the possibility of accidental opening of the explosion-proof valve 100 increases, thereby affecting the normal operation of the battery cell. If the total opening pressure of the explosion-proof valve 100 is too high, the opening speed of the explosion-proof valve 100 after a battery cell loses control can be affected, potentially posing a safety risk to the battery cell. In one embodiment of the present application, when the temperature of the explosion-proof valve 100 is lower than the preset temperature, the critical pressure value at which both the explosion-proof disc 2 and the temperature-sensitive membrane 3 rupture is PA1, 0.4Mpa≤PA1≤1.2Mpa; when the temperature of the explosion-proof valve 100 is higher than the preset temperature, the critical pressure value at which both the explosion-proof disc 2 and the temperature-sensitive membrane 3 rupture is PA2, 0.2Mpa≤PA2≤1Mpa. After testing, under this pressure limit, the possibility of the explosion-proof valve 100 being opened by mistake can be reduced, and the response speed of the explosion-proof valve 100 can be improved.

[0069] The explosion-proof valve 100 is preset to a temperature T, 55° ≤ T ≤ 65°. Within this temperature limit, the temperature-sensitive membrane 3 is prevented from prematurely softening, which could cause the explosion-proof valve 100 to open prematurely. It also prevents the temperature-sensitive membrane 3 from softening too late, which could affect the response speed of the explosion-proof valve 100 and the safety performance of the battery cell. In particular, when T = 60°, the temperature-sensitive membrane 3 is able to better balance the relationship between opening force and response speed.

[0070] To ensure that the critical rupture pressure of explosion-proof disc 2 meets the requirements of explosion-proof valve 100, the critical rupture pressure of the explosion-proof disc is PA3. PA3 must satisfy the relationship: 0.2Mpa ≤ PA3 ≤ 0.8Mpa or 0.3Mpa ≤ PA3 ≤ 1Mpa. 0.2Mpa ≤ PA3 ≤ 0.8Mpa is the critical rupture pressure of explosion-proof disc 2 when used in iron-lithium batteries, and 0.3Mpa ≤ PA3 ≤ 1Mpa is the critical rupture pressure of explosion-proof disc 2 when used in ternary lithium batteries. Within this critical rupture pressure limit, the opening pressure of explosion-proof valve 100 is guaranteed to be greater than the safe opening pressure, reducing the possibility of accidental opening of explosion-proof valve 100. It also ensures that if the battery cell loses control, the explosion-proof disc 2 can be quickly breached by the air pressure within the containment chamber, thereby improving the response speed of explosion-proof valve 100.

[0071] Please refer to Figure 4. The explosion-proof disc 2 is provided with a notched groove 21. The notched groove 21 is used to adjust the critical pressure value of the explosion-proof disc 2. The notched groove 21 is provided on the side of the explosion-proof disc 2 facing the temperature-sensitive membrane 3. The outer edge of the notched groove 21 is surrounded to form a pressure relief area 211. When the pressure on the explosion-proof disc 2 is greater than the critical pressure value of the explosion-proof disc 2, the pressure will first break through the pressure relief area 211 and be released. By adjusting the depth of the notched groove 21, the critical pressure value of the explosion-proof disc 2 can be adjusted. It should be noted that the critical pressure value of the explosion-proof disc 2 refers to the minimum pressure value required to cause the explosion-proof disc 2 to rupture. When the pressure on the explosion-proof disc 2 is greater than the critical pressure value of the explosion-proof disc 2, the explosion-proof disc 2 ruptures, thereby allowing the pressure in the accommodating cavity to be released through the pressure relief hole 11.

[0072] Please refer to Figures 5 and 6 to ensure that the explosion-proof disc can meet the above-mentioned critical rupture pressure value requirements. In one embodiment of the present application, the explosion-proof disc 2 satisfies at least one of the following relationships: 0.02mm≤H≤0.1mm, 0.2mm≤J≤1mm. Here, H is the minimum distance from the bottom of the notched groove 21 to the side of the explosion-proof disc 2 facing away from the temperature-sensitive membrane 3, and J is the thickness of the explosion-proof disc 2. Within this size limit, it can ensure that the opening pressure of the explosion-proof valve 100 is greater than the safe opening pressure, reducing the possibility of the explosion-proof valve 100 being accidentally opened. It can also ensure that when the battery cell loses control, the explosion-proof disc 2 can be quickly broken by the air pressure in the containment chamber. This thereby improves the response speed of the explosion-proof valve 100.

[0073] In one possible embodiment of the present application, the outer edge of the orthographic projection of the notched groove 21 is located within the orthographic projection of the temperature-sensitive membrane 3, so that the entire pressure relief area 211 is covered within the temperature-sensitive membrane 3, thereby increasing the contact area between the temperature-sensitive membrane 3 and the pressure relief area 211, thereby reducing the possibility of the pressure in the accommodating cavity passing through the temperature-sensitive membrane 3 and directly acting on the pressure relief area 211, thereby increasing the opening pressure of the explosion-proof valve 100 and reducing the possibility of the explosion-proof valve 100 being opened by mistake.

[0074] In one embodiment of the present application, the pressure relief area 211 and the temperature-sensitive membrane 3 satisfy the relationship: 1mm≤FG≤1.5mm, where F is the length of the temperature-sensitive membrane 3 along the length of the explosion-proof valve 100, G is the length of the pressure relief area 211 along the length of the explosion-proof valve 100, and FG is the difference between the length of the temperature-sensitive membrane 3 along the length of the explosion-proof valve 100 and the length of the pressure relief area 211 along the length of the explosion-proof valve 100. Within this size limit, the temperature-sensitive membrane 3 can be fully covered with the pressure relief area 211, while also saving material for the temperature-sensitive membrane 3 and reducing the manufacturing cost of the temperature-sensitive membrane 3.

[0075] The temperature-sensitive membrane 3 is connected to the main body 1. The temperature-sensitive membrane 3 can be adhered to the main body 1 by glue or by hot melting. The temperature-sensitive membrane 3 is used to cover the pressure relief hole 11 together with the explosion-proof plate 2. The temperature-sensitive membrane 3 is made of plastic. The plastic can be polypropylene, polyethylene, or polyethylene glycol terephthalate. The plastic is used to make the critical rupture pressure value of the temperature-sensitive membrane 3 inversely proportional to the temperature of the explosion-proof valve 100. When the battery cell is in normal working conditions, the temperature-sensitive membrane 3 and the explosion-proof plate 2 jointly cover the pressure relief hole 11 of the main body 1, thereby increasing the opening pressure of the pressure relief hole 11 and reducing the risk of the pressure relief hole 11 being opened by mistake. When the battery cell is out of control, the high temperature after the battery cell is out of control will cause the temperature-sensitive membrane 3 to be softened quickly, thereby reducing the critical rupture pressure value of the temperature-sensitive membrane 3 and reducing the opening pressure of the explosion-proof valve 100, thereby achieving the purpose of opening the valve in advance.

[0076] In order to facilitate the explanation of the beneficial effects of the early opening of the temperature-sensitive membrane 3, it is assumed that the safety opening pressure of the explosion-proof valve is 1Mpa. The safety opening pressure refers to the minimum opening pressure that each qualified explosion-proof valve must have. If the opening pressure of the explosion-proof valve is less than the safety opening pressure, the explosion-proof valve will be opened in advance, affecting the normal use of the battery cell. The opening pressure of the explosion-proof valve in the related art and the explosion-proof valve provided in this application are both taken as the safety opening pressure. Since the opening pressure of the explosion-proof valve 100 is constant in the related art, the air pressure in the accommodating chamber needs to reach 1Mpa in the related art before the explosion-proof valve 100 can be opened. In the present application, the critical rupture pressure value of the temperature-sensitive membrane 3 can be set to 0.4Mpa, and the critical rupture pressure value of the explosion-proof plate 2 can be set to 0.6Mpa. At this time, the opening pressure of the explosion-proof valve 100 is also 1Mpa, which meets the minimum opening pressure of the explosion-proof valve 100. When the battery cell loses control, the temperature-sensitive membrane 3 softens, and the critical rupture pressure of the temperature-sensitive membrane 3 is reduced to 0. At this time, the opening pressure of the explosion-proof valve 100 is only 0.6 MPa, the critical rupture pressure of the explosion-proof disc 2. In other words, at this time, the air pressure in the battery cell housing chamber only needs to reach 0.6 MPa to complete the opening of the explosion-proof valve 100. Compared with related technologies, the explosion-proof valve 100 of the present application requires a lower opening pressure, has a faster response speed, and has higher battery cell safety performance.

[0077] In order to ensure that when the temperature of the explosion-proof valve 100 is lower than the preset temperature, the critical pressure value at which both the explosion-proof disc 2 and the temperature-sensitive membrane 3 rupture can reach PA1, and when the temperature of the explosion-proof valve 100 is higher than the preset temperature, the critical pressure value at which both the explosion-proof disc 2 and the temperature-sensitive membrane 3 rupture is PA2, in one embodiment of the present application, the temperature-sensitive membrane 3 satisfies the following relationship: PA3=Z*PA2; wherein PA2 is the critical pressure value at which the temperature-sensitive membrane 3 ruptures when the temperature of the explosion-proof valve 100 is lower than the preset temperature; PA3 is the critical pressure value at which the temperature-sensitive membrane 3 ruptures when the temperature of the explosion-proof valve 100 is higher than the preset temperature; Z is a constant, and 0≤Z≤0.25. Tests have shown that when the temperature of the explosion-proof valve 100 reaches 60°C, the critical rupture pressure of the temperature-sensitive membrane 3 can be reduced to 1 / 4 of the critical rupture pressure of the temperature-sensitive membrane 3 before the battery cell loses control. When the temperature of the explosion-proof valve 100 reaches 80°C, the critical rupture pressure of the temperature-sensitive membrane 3 can be reduced to 1 / 20 of the critical rupture pressure of the temperature-sensitive membrane 3 before the battery cell loses control. When the temperature of the explosion-proof valve 100 reaches 120°C, the critical rupture pressure of the temperature-sensitive membrane 3 can be reduced to 0. In this way, the influence of the temperature-sensitive membrane on the opening force of the explosion-proof valve 100 is minimized when the battery cell loses control, thereby improving the response speed of the explosion-proof valve 100.

[0078] In order to satisfy the above relationship, the plastic used for the temperature-sensitive membrane 3 includes at least one of polypropylene, polyethylene and polyethylene glycol terephthalate. The thickness of the temperature-sensitive membrane 3 is A, 0.05mm≤A≤0.5mm. After experimental testing, under the restrictions of the above materials and dimensions, it can not only ensure that the temperature-sensitive membrane 3 maintains a high opening force when the battery cell is in a normal state, thereby reducing the possibility of the explosion-proof valve 100 being opened by mistake, but also ensure that the temperature-sensitive membrane 3 can be quickly melted when the battery cell is out of control, thereby improving the response speed of the explosion-proof valve 100.

[0079] Please refer to Figure 7. Due to the limitations of existing material molding technology, micropores will be formed on the surface of the temperature-sensitive membrane 3 during molding, and the thicker the molding thickness of the temperature-sensitive membrane 3, the more micropores there are on the surface of the temperature-sensitive membrane 3. When the temperature-sensitive membrane 3 comes into contact with the electrolyte in the battery cell, the electrolyte will penetrate into the micropores, thereby accelerating the corrosion of the temperature-sensitive membrane. To solve the above problems, please refer to Figure 6. In one embodiment of the present application, the temperature-sensitive membrane 3 includes a plurality of temperature-sensitive layers 31, and the two temperature-sensitive layers 31 are stacked and interconnected in sequence along the axial direction of the pressure relief hole 11 to form a final temperature-sensitive membrane 3. The number of layers of the temperature-sensitive layer 31 can be set to two layers, or three layers, or four layers, and this application does not impose any restrictions on this. This application reduces the number of micropores on the surface of the temperature-sensitive membrane 3 and extends the service life of the temperature-sensitive membrane 3 by disassembling the thicker temperature-sensitive membrane 3 into a plurality of thinner temperature-sensitive layers 31.

[0080] The material of each temperature-sensing layer 31 can be the same or different, and this application does not impose any restrictions on this. In one embodiment of the present application, the material of each temperature-sensing layer 31 is set to be the same. In this way, the melting point consistency of each temperature-sensing layer 31 is maintained, thereby reducing the difficulty of hot-melt connection of each temperature-sensing layer 31 and improving the production efficiency of the temperature-sensing film 3.

[0081] When the material of each temperature-sensing layer 31 is set to be the same, the material of the temperature-sensing layer 31 can be polypropylene, polyethylene, or polyethylene terephthalate. This application does not limit this. In one embodiment of the present application, the material of each temperature-sensing layer 31 includes polyethylene. Compared with other materials, polyethylene has higher adhesion to metal, which can improve the stability of the connection between the temperature-sensing film 3 and the main body 1.

[0082] To ensure that each temperature-sensitive layer 31 is made of the same material, the temperature-sensitive film satisfies the equation: PA3 = Z * PA2. In one embodiment of the present application, the thickness of the temperature-sensitive film 3 is A, 0.12mm ≤ A ≤ 0.18mm, and the thickness of each temperature-sensitive layer 31 is B, 0.04mm ≤ B ≤ 0.06mm. Within this size constraint, the temperature-sensitive film 3, composed of multiple temperature-sensitive layers 31 of the same material, will neither soften too quickly, causing premature opening of the explosion-proof valve 100, nor soften too slowly, affecting the response speed of the explosion-proof valve 100.

[0083] The material of each temperature-sensing layer 31 can also be set to be different. Specifically, in this embodiment, the temperature-sensing layer 31 includes a first temperature-sensing layer 31a, a second temperature-sensing layer 31b, and a third temperature-sensing layer 31c. The third temperature-sensing layer 31c is connected to the main body 1. The first temperature-sensing layer 31a and the third temperature-sensing layer 31c are made of polypropylene, and the second temperature-sensing layer 31b is made of polyethylene terephthalate. The second temperature-sensing layer 31b serves as the main body 1 of the temperature-sensing membrane 3. Polyethylene terephthalate can effectively improve the ductility of the second temperature-sensing layer 31b, thereby increasing the opening force of the explosion-proof valve 100 and reducing the possibility of the explosion-proof valve 100 being accidentally opened. The first temperature-sensing layer 31a and the third temperature-sensing layer 31c are arranged on both sides of the first temperature-sensing layer 31a. The first temperature-sensing layer 31a and the third temperature-sensing layer 31c are made of polypropylene with relatively high hardness. In this way, the second temperature-sensing layer 31b is protected to prevent the second temperature-sensing layer 31b from being punctured by other objects during the assembly process of the explosion-proof valve 100, thereby improving the yield rate of the explosion-proof valve 100.

[0084] To ensure that the material of each temperature-sensitive layer 31 is different, the temperature-sensitive film 3 satisfies the relationship: PA3 = Z * PA2. In one embodiment of the present application, the temperature-sensitive film 3, the first temperature-sensitive layer 31a, the second temperature-sensitive layer 31b, and the third temperature-sensitive layer 31c satisfy at least one of the following relationships: 0.07mm≤A≤0.13mm, 0.02mm≤C≤0.04mm, 0.03mm≤D≤0.05mm, and 0.02mm≤E≤0.04mm, where A is the thickness of the temperature-sensitive film 3, C is the thickness of the first temperature-sensitive layer 31a, D is the thickness of the second temperature-sensitive layer 31b, and E is the thickness of the third temperature-sensitive layer 31c. Within this size limit, the temperature-sensitive film 3 composed of multiple temperature-sensitive layers 31 of the same material will neither cause the explosion-proof valve 100 to open prematurely due to excessive softening, nor will it affect the response speed of the explosion-proof valve 100 due to excessive softening.

[0085] Please refer to Figure 2. There are many ways to set up the explosion-proof disc 2 and the temperature-sensitive membrane 3. The explosion-proof disc 2 and the temperature-sensitive membrane 3 can be covered on the pressure relief hole 11 along the same side of the main body 1, or can be covered on both ends of the pressure relief hole 11 along both sides of the main body 1. This application does not limit this. In one embodiment of the present application, the temperature-sensitive membrane 3 and the explosion-proof disc 2 are arranged on the side of the main body 1 facing the accommodating cavity, the temperature-sensitive membrane 3 is in contact with the explosion-proof disc 2, and the temperature-sensitive membrane 3 is at least partially located on the side of the explosion-proof disc 2 away from the main body 1. When the battery cell is in normal working condition, the temperature-sensitive membrane 3 and the explosion-proof disc 2 are in contact with each other and support each other, thereby increasing the opening pressure of the explosion-proof valve 100. When the battery cell is out of control, the temperature-sensitive membrane 3 is softened, and the critical rupture pressure value of the temperature-sensitive membrane 3 is reduced, so as to increase the opening speed of the explosion-proof valve 100 when the battery cell is out of control. At the same time, since the temperature-sensitive membrane 3 and the explosion-proof disk 2 are arranged along the same side of the main body 1, the temperature-sensitive membrane 3, the explosion-proof disk 2 and the main body 1 can be connected to each other through only one hot melt, thereby improving the assembly efficiency of the explosion-proof valve 100.

[0086] To improve the stability of the explosion-proof disc 2, in one embodiment of the present application, a mounting groove 12 is provided on one side of the main body 1. The mounting groove 12 is connected to the pressure relief hole 11. The mounting groove 12 has a notch on the side away from the pressure relief hole 11. The explosion-proof disc 2 is disposed in the mounting groove 12; the temperature-sensitive membrane 3 is covered in the notch. The provision of the mounting groove 12, on the one hand, can provide positioning for the installation of the explosion-proof disc 2, thereby improving the stability of the connection between the explosion-proof disc 2 and the main body. On the other hand, the mounting groove 12 can reduce the height of the explosion-proof disc 2 protruding from the main body 1, thereby leaving space for the temperature-sensitive membrane 3 to extend outward under the action of pressure, thereby increasing the opening pressure of the explosion-proof valve 100 and reducing the possibility of the explosion-proof valve 100 being opened by mistake.

[0087] When the temperature-sensitive membrane 3 and the explosion-proof disc 2 are attached to each other, in order to ensure that the explosion-proof valve 100 can be opened in time when the battery cell is out of control. In one embodiment of the present application, the explosion-proof disc 2 and the temperature-sensitive membrane 3 satisfy the relationship: PA2 = X*PA3; wherein PA2 is the critical rupture pressure value of the temperature-sensitive membrane 3 when the temperature of the explosion-proof valve 100 is lower than the preset temperature, PA3 is the critical rupture pressure value of the explosion-proof disc 2, X is a constant, and X satisfies 0.1≤X≤0.5. That is, when the temperature-sensitive membrane 3 and the explosion-proof disc 2 are attached to each other, the critical rupture pressure value of the temperature-sensitive membrane 3 when the temperature of the explosion-proof valve 100 is lower than the preset temperature is between one tenth and one half of the critical rupture pressure value of the explosion-proof disc 2. Under the constraints of this relationship, the opening pressure of the explosion-proof valve 100 will not be excessively concentrated on the explosion-proof disc 2, which will cause the explosion-proof disc 2 to be difficult to open after the temperature-sensitive membrane 3 softens. It will not cause the opening pressure of the explosion-proof valve 100 to be excessively concentrated on the temperature-sensitive membrane 3, thereby increasing the thickness of the temperature-sensitive membrane 3, prolonging the softening time of the temperature-sensitive membrane 3, and reducing the response speed of the explosion-proof valve 100.

[0088] As can be understood from the above relationship, the critical rupture pressure of the temperature-sensitive membrane 3 determines the opening speed of the explosion-proof valve 100. The critical rupture pressure of the explosion-proof disc 2 determines the ultimate opening pressure of the explosion-proof valve 100. To ensure that the opening pressure of the explosion-proof valve 100 is greater than the safe opening pressure of the explosion-proof valve 100, in the above embodiment, the explosion-proof disc 2 satisfies the relationship: 0.2Mpa≤PA3≤0.8Mpa or 0.3Mpa≤PA3≤1Mpa, where PA3 is the critical rupture pressure of the explosion-proof disc 2, 0.2Mpa≤PA3≤0.8Mpa is the critical rupture pressure of the explosion-proof disc 2 when it is used in iron-lithium batteries, and 0.3Mpa≤PA3≤1Mpa is the critical rupture pressure of the explosion-proof disc 2 when it is used in ternary lithium batteries. Within the limit of this critical rupture pressure, the opening pressure of the explosion-proof valve 100 is ensured to be greater than the safe opening pressure, reducing the possibility of the explosion-proof valve 100 being accidentally opened. It can also ensure that when the battery cell loses control, the explosion-proof disc 2 can be quickly broken by the air pressure in the accommodation chamber, thereby improving the response speed of the explosion-proof valve 100.

[0089] Please refer to Figure 8. In other possible embodiments of the present application, the explosion-proof disc 2 and the temperature-sensitive membrane 3 can also be arranged on both sides of the main body 1. Specifically, in one possible embodiment of the present application, the main body 1 includes a first surface and a second surface arranged opposite to each other, the second surface facing the accommodating cavity, and the pressure relief hole 11 passes through the first surface and the second surface; the explosion-proof disc 2 is arranged on the first surface, and the temperature-sensitive membrane 3 is arranged on the second surface. When the temperature-sensitive membrane 3 is subjected to pressure from the accommodating cavity, the temperature-sensitive membrane 3 can extend and deform into the pressure relief hole 11, and eventually contact the explosion-proof disc 2 arranged on the other side of the pressure relief hole 11, and then share the air pressure from the accommodating cavity with the explosion-proof disc 2, thereby increasing the opening pressure of the explosion-proof valve 100 and reducing the possibility of the explosion-proof valve 100 being accidentally opened. The pressure relief hole 11 also leaves space for the extension of the temperature-sensitive membrane 3, thereby increasing the critical rupture pressure value of the temperature-sensitive membrane 3, increasing the opening pressure of the explosion-proof valve 100, and reducing the possibility of the explosion-proof valve 100 being accidentally opened.

[0090] It can be understood that in the above embodiment, the depth of the pressure relief hole 11 affects the critical pressure value of the rupture of the temperature-sensitive membrane 3. If the depth of the pressure relief hole 11 is too deep, the temperature-sensitive membrane 3 will not be able to contact the explosion-proof disc 2, thereby affecting the normal use of the temperature-sensitive membrane 3. If the depth of the pressure relief hole 11 is too shallow, it will reduce the expansion space of the temperature-sensitive membrane 3, thereby reducing the critical pressure value of the rupture of the temperature-sensitive membrane 3. In order to solve the above problem, in one embodiment of the present application, the depth of the pressure relief hole 11 is K, 0.5mm≤K≤2mm. Under this size limit, it can ensure that the temperature-sensitive membrane 3 can fit with the explosion-proof disc 2, and it can also ensure that the temperature-sensitive membrane 3 has a certain ductility, thereby increasing the critical pressure value of the rupture of the temperature-sensitive membrane 3, increasing the opening pressure of the explosion-proof valve 100, and reducing the possibility of the explosion-proof valve 100 being opened by mistake.

[0091] It can be understood that since the pressure relief hole 11 can increase the extension distance of the temperature-sensitive membrane 3, and thus increase the critical rupture pressure value of the temperature-sensitive membrane 3, when the opening pressure of the explosion-proof valve 100 and the thickness of the temperature-sensitive membrane 3 remain unchanged, the temperature-sensitive membrane 3 can be assigned a larger critical rupture pressure value. In one embodiment of the present application, the explosion-proof disc 2 and the temperature-sensitive membrane 3 satisfy the relationship: PA2 = Y*PA3; wherein PA2 is the critical rupture pressure value of the temperature-sensitive membrane 3 when the temperature of the explosion-proof valve 100 is lower than the preset temperature, PA3 is the critical rupture pressure value of the explosion-proof disc 2, Y is a constant, and 0.2≤Y≤0.6. That is, at this time, the critical rupture pressure value assigned to the explosion-proof disc 2 is between 1 / 5 and 3 / 5 of the explosion-proof disc 2, so as to reduce the critical rupture pressure value of the explosion-proof disc 2, reduce the pressure required to open the explosion-proof disc 2, and improve the response speed of the explosion-proof valve 100.

[0092] In the description of the embodiments of the present application, it should be noted that the orientation or positional relationship of terms such as "center", "up", "down", "left", "right", "vertical", "horizontal", "inside", and "outside" are based on the orientation or positional relationship described in the accompanying drawings. They are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, they cannot be understood as limitations on the present application.

[0093] The above disclosure is only a preferred embodiment of the present application, and certainly cannot be used to limit the scope of rights of the present application. Ordinary technicians in this field can understand that all or part of the processes of the above embodiment and equivalent changes made in accordance with the claims of the present application are still within the scope covered by the present application.

Claims

1. An explosion-proof valve, comprising a main body (1), an explosion-proof disc (2) and a temperature-sensitive membrane (3), wherein the main body (1) is provided with a pressure relief hole (11) penetrating along the thickness direction thereof; the explosion-proof disc (2) and the temperature-sensitive membrane (3) are connected to the main body (1) and cover the pressure relief hole (11); the temperature-sensitive membrane (3) is made of plastic so that the critical rupture pressure value of the temperature-sensitive membrane (3) is inversely proportional to the temperature of the explosion-proof valve; in, The thickness of the temperature-sensitive film (3) is A, 0.05 mm ≤ A ≤ 0.5 mm.

2. The explosion-proof valve according to claim 1, wherein the temperature-sensitive membrane (3) comprises at least two temperature-sensitive layers (31) stacked in sequence along the axis direction of the pressure relief hole (11). 3 . The explosion-proof valve according to claim 1 , wherein the plastic comprises at least one of polypropylene, polyethylene and polyethylene terephthalate.

4. The explosion-proof valve according to claim 3, wherein the plastic material used in each temperature-sensing layer (31) is the same, and the thickness of each temperature-sensing layer (31) is B, 0.04 mm ≤ B ≤ 0.06 mm.

5. The explosion-proof valve according to claim 3, wherein the temperature-sensitive layer (31) comprises a first temperature-sensitive layer (31a) temperature-sensitive layer (31), a second temperature-sensitive layer (31b) temperature-sensitive layer (31), and a third temperature-sensitive layer (31c) temperature-sensitive layer (31), and the third temperature-sensitive layer (31c) temperature-sensitive layer (31) is connected to the main body (1); The material of the first temperature-sensing layer (31a) temperature-sensing layer (31) and the third temperature-sensing layer (31c) temperature-sensing layer (31) includes polypropylene, and the material of the second temperature-sensing layer (31b) temperature-sensing layer (31) includes polyethylene terephthalate; The thickness of the temperature-sensitive film (3) is A, 0.07 mm ≤ A ≤ 0.13 mm.

6. The explosion-proof valve according to claim 5, wherein the first temperature-sensing layer (31a) temperature-sensing layer (31), the second temperature-sensing layer (31b) temperature-sensing layer (31), and the third temperature-sensing layer (31c) temperature-sensing layer (31) satisfy at least one of the following relationships: 0.02 mm ≤ C ≤ 0.04 mm, 0.03 mm ≤ D ≤ 0.05 mm, and 0.02 mm ≤ E ≤ 0.04 mm; in, C is the thickness of the first temperature-sensing layer (31a) temperature-sensing layer (31); D is the thickness of the second temperature-sensing layer (31b) temperature-sensing layer (31); E is the thickness of the third temperature-sensing layer (31c) temperature-sensing layer (31).

7. The explosion-proof valve according to any one of claims 1 to 6, wherein a notch groove (21) is provided on a side of the explosion-proof disc (2) facing the temperature-sensitive membrane (3), and an outer edge of the notch groove (21) is surrounded to form a pressure relief area (211); Along the length direction of the explosion-proof valve, the length of the temperature-sensitive membrane (3) is F, the length of the pressure relief area (211) is G, and 1mm≤FG≤1.5mm.

8. The explosion-proof valve according to any one of claims 1 to 6, wherein a notched groove (21) is provided on the side of the explosion-proof disc (2) facing the temperature-sensitive membrane (3); The minimum distance from the bottom of the notched groove (21) to the side of the explosion-proof plate (2) facing away from the temperature-sensitive membrane (3) is H, and 0.02mm≤H≤0.1mm.

9. The explosion-proof valve according to any one of claims 1 to 6, wherein the thickness of the explosion-proof disc (2) is J, 0.2 mm ≤ J ≤ 1 mm.

10. The explosion-proof valve according to any one of claims 1 to 6, wherein the main body (1) comprises a first surface and a second surface arranged opposite to each other, and the pressure relief hole (11) passes through the first surface and the second surface; The explosion-proof plate (2) is arranged on the first surface, and the temperature-sensitive membrane (3) is arranged on the second surface.

11. The explosion-proof valve according to claim 10, wherein the depth of the pressure relief hole (11) is K, and 0.5 mm ≤ K ≤ 2 mm.

12. A cover plate assembly comprising the explosion-proof valve according to any one of claims 1 to 11.

13. A battery cell comprising the cover plate assembly according to claim 12.

14. A battery pack comprising the battery cell according to claim 13.

15. An electric power system comprising the battery pack according to claim 14.

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