Explosion-proof valve of energy storage battery

Abstract

The utility model discloses an energy storage battery explosion-proof valve which comprises a base body, a thermoplastic film, a waterproof breathable film and a one-way valve, the base body is provided with a first pressure relief hole and a second pressure relief hole, the thermoplastic film is connected with the base body in a sealing mode and covers the first pressure relief hole, the thermoplastic film is provided with a breathable hole, and the orthographic projection of the breathable hole on the base body is located in the first pressure relief hole. The waterproof breathable film is in sealed connection with the thermoplastic film and covers the breathable hole, and the one-way valve is connected with the base body and used for opening and closing the second pressure relief hole. When the explosion-proof valve of the energy storage battery works normally, the waterproof and breathable film is used for water resistance, breathability and pressure balance, in the initial stage of thermal runaway of a battery pack, the one-way valve is opened, pressure is released from the second pressure release hole, and once the battery pack is seriously thermally runaway and reaches the melting point of the thermoplastic film, the thermoplastic film begins to melt; and then the first pressure relief hole is quickly opened to release gas in the battery pack, so that the battery pack is prevented from exploding, and the battery pack is safer and more reliable.

Description

Technical Field

[0001] The utility model relates to the technical field of batteries, in particular to an explosion-proof valve for energy storage batteries. Background Art

[0002] In the wind, solar, and automotive power storage battery manufacturing industry, lithium-ion batteries, with their high energy density and long cycle life, have become a key component in new energy vehicles. In recent years, thermal runaway incidents in new energy vehicles have become frequent. The main cause is heat accumulation caused by exothermic side reactions within the battery cells. The rate of heat exchange from the battery cells to the outside is slower than the rate of heat accumulation, causing the temperature to continue to rise until it reaches the ignition point, causing combustion and explosion.

[0003] Currently, the main solution to this problem is to quickly discharge toxic gases, pressure and heat through explosion-proof valves, thereby prolonging the time of explosion and fire.

[0004] There are two main types of explosion-proof valves currently available on the market: piston-spring-type and ejector-type. Under normal operating conditions, the piston-spring-type explosion-proof valve maintains a pressure differential between the inside and outside of the battery pack casing primarily through the waterproof, breathable membrane. In this state, the explosion-proof valve acts as a breathing valve. When the battery pack experiences thermal runaway—when the internal pressure significantly exceeds the valve's opening pressure—the internal gas pressure displaces the valve's built-in spring piston rod, opening the check valve and allowing gas to flow directly to the outside environment through an unobstructed path. This allows for rapid gas discharge, rapidly reducing internal pressure and preventing explosion. After a period of venting, when the internal pressure decreases and is below the spring force, the piston rod returns to its original position, closing the explosion-proof valve. This prevents the continued discharge of high-temperature gases generated by thermal runaway from the casing. Heat buildup within the casing can easily lead to continued thermal runaway of the battery cells within, compromising the safety of the battery pack. Utility Model Content

[0005] The purpose of the utility model is to provide a safe and reliable explosion-proof valve for energy storage batteries.

[0006] In order to achieve the above-mentioned purpose, the technical solution proposed by the present utility model is:

[0007] An energy storage battery explosion-proof valve comprises: a base, a thermoplastic membrane, a waterproof breathable membrane, and a one-way valve. The base is provided with a first pressure relief hole and a second pressure relief hole. The thermoplastic membrane is sealed and connected to the base and covers the first pressure relief hole. The thermoplastic membrane is provided with an air hole, the orthographic projection of the air hole on the base is located within the first pressure relief hole. The waterproof breathable membrane is sealed and connected to the thermoplastic membrane and covers the air hole. The one-way valve is connected to the base and is used to open and close the second pressure relief hole.

[0008] Preferably, the orthographic projection of the waterproof breathable membrane on the substrate is located inside the first pressure relief hole.

[0009] Preferably, the base is provided with a mounting hole. The one-way valve comprises: a valve stem, an umbrella-shaped valve cover connected to one end of the valve stem, and a stopper connected to the other end of the valve stem, wherein the umbrella-shaped valve cover is made of an elastic material, the valve stem is inserted into the mounting hole, the end edge of the umbrella-shaped valve cover facing the valve stem elastically abuts against the outer surface of the base, and the end edge of the stopper facing the valve stem abuts against the inner surface of the base.

[0010] Preferably, the mounting hole is configured as a tapered hole whose diameter shrinks from the outer surface to the inner surface of the base, and the outer peripheral wall of the end of the limiting portion away from the valve stem is configured as a guide slope.

[0011] Preferably, the base body is provided with a plurality of second pressure relief holes arranged around the mounting hole along the circumference of the mounting hole, and the second pressure relief holes are fan-shaped.

[0012] Preferably, the base body is formed with a convex ring protruding outward on the outer side of the one-way valve, and the air vent and the mounting hole are located in the convex ring.

[0013] Preferably, a hollow support member connected to the base is provided in the first pressure relief hole, and the hollow support member is used to support the thermoplastic membrane and / or the waterproof breathable membrane.

[0014] Preferably, a plurality of metal embedded nuts are embedded in the base along the circumferential direction, and a sealing ring protruding from the inner surface of the base is embedded in the inner surface of the base.

[0015] Preferably, the melting point of the thermoplastic film is 100-260°C.

[0016] Preferably, the one-way valve is made of one of silicone, natural rubber, nitrile rubber and thermoplastic elastomer.

[0017] Preferably, the waterproof and breathable membrane is made of e-PTFE.

[0018] Preferably, the thermoplastic film is made of one of PP, PA, PE, ABS, TPU and PVDF.

[0019] Preferably, the substrate is made of one of flame retardant reinforced PBT, flame retardant reinforced PA, flame retardant reinforced PC and flame retardant reinforced PPS.

[0020] By adopting the above technical solution, the beneficial effects of the utility model are as follows: when the battery pack is working normally, the energy storage battery explosion-proof valve of the utility model is waterproof and breathable and pressure balanced through the waterproof and breathable membrane. In the early stage of thermal runaway of the battery pack, the one-way valve is opened to release pressure from the second pressure relief hole. Once the battery pack is seriously thermally runaway and reaches the melting point of the thermoplastic film, the thermoplastic film begins to melt, and the waterproof and breathable film is separated from the substrate, and then the first pressure relief hole is quickly opened to release the gas inside the battery pack, preventing the battery pack from exploding, which is safer and more reliable. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 The figure is a schematic diagram of the three-dimensional structure of an energy storage battery explosion-proof valve according to a preferred embodiment of the present utility model.

[0022] Figure 2 for Figure 1 Schematic diagram of the explosion structure.

[0023] Figure 3 for Figure 1 Schematic diagram of the rear view.

[0024] Figure 4 for Figure 1 Isometric half-section diagram of .

[0025] Among them: 1. Base; 11. First pressure relief hole; 12. Second pressure relief hole; 13. Mounting hole; 14. Raised ring; 15. Hollow support member; 16. Metal embedded nut; 17. Sealing ring; 2. Thermoplastic membrane; 21. Air vent; 3. Waterproof and breathable membrane; 4. One-way valve; 41. Valve stem; 42. Umbrella-shaped valve cover; 43. Limiting part; 431. Guide slope. DETAILED DESCRIPTION

[0026] The present invention will be further described below with reference to the accompanying drawings and specific implementation methods.

[0027] like Figures 1 to 4 As shown, the energy storage battery explosion-proof valve of this embodiment includes: a base body 1, a thermoplastic membrane 2, a waterproof breathable membrane 3 and a one-way valve 4, wherein the base body 1 is provided with a first pressure relief hole 11 and a second pressure relief hole 12, the thermoplastic membrane 2 is sealed and connected to the base body 1 and covers the first pressure relief hole 11, the thermoplastic membrane 2 is provided with an air hole 21, the waterproof breathable membrane 3 is sealed and connected to the thermoplastic membrane 2 and covers the air hole 21, and the one-way valve 4 is installed on the base body 1 for opening and closing the second pressure relief hole 12.

[0028] In this embodiment, the thermoplastic film 2 and the substrate 1 as well as the waterproof and breathable membrane 3 and the thermoplastic film 2 can be connected by adhesive bonding or welding (such as ultrasonic welding).

[0029] The melting point of the thermoplastic film 2 of this embodiment is 100-260°C, and its material can be selected from PP (polypropylene), PA (polyamide), PE (polyethylene), ABS (acrylonitrile-styrene-butadiene copolymer), TPU (thermoplastic polyurethane elastomer), PVDF (polyvinylidene fluoride), etc. The appropriate melting point and material can be selected according to actual conditions, and PP material with a melting point of 150-180°C is preferred.

[0030] The waterproof and breathable membrane 3 of this embodiment can be made of e-PTFE (expanded polytetrafluoroethylene) material.

[0031] In order to ensure that the waterproof breathable membrane 3 is separated from the substrate 1 as the thermoplastic membrane 2 melts, the orthographic projection of the waterproof breathable membrane 3 on the substrate 1 needs to be located inside the first pressure relief hole 11, that is, the four edges of the waterproof breathable membrane 3 are connected to the substrate 1 through the thermoplastic membrane 2. When the thermoplastic membrane 2 melts at high temperature, the waterproof breathable membrane 3 will naturally fall off.

[0032] In this embodiment, a hollow support member 15 connected to the base 1 is provided in the first pressure relief hole 11. The hollow support member 15 is used to support the thermoplastic membrane 2 and the waterproof breathable membrane 3. The shape of the hollow support member 15 is not limited, as long as it does not affect the waterproof breathable membrane 3 to balance the air pressure inside and outside the battery pack shell and the high-temperature melting of the thermoplastic membrane 2. In this embodiment, the hollow support member 15 includes an annular portion and a plurality of connecting portions. The annular portion is connected to the base 1 through a plurality of connecting portions arranged at intervals along the circumference of the annular portion. The orthographic projection of the annular portion on the thermoplastic membrane 2 surrounds the outside of the air vent 21 and is located on the inside of the waterproof breathable membrane 3.

[0033] In other preferred embodiments of the present invention, the one-way valve 4 can also be a commercially available one-way valve 4, such as a piston spring-type explosion-proof valve, which can be directly installed into the second pressure relief hole 12. A piston spring-type explosion-proof valve is sealed by spring force. When opening, the pressure differential between the inside and outside of the battery pack housing must overcome the spring force. This creates a conflict between the desired low opening pressure and the high compression of the O-ring. Specifically, the slider securing the breathable membrane must press against the O-ring on the main body, and this pressure primarily comes from the spring's contraction. The market demand for thermal runaway opening pressures for piston spring-type explosion-proof valves is decreasing. The desired opening pressure for battery packs is less than 4-7 kPa, which means the O-ring compression rate must be less than 20%. In this case, the O-ring's airtightness may be compromised. Furthermore, battery packs face complex operating conditions. Water leakage can occur in the battery pack if exposed to water, especially if the contact surface around the waterproof ring is rusted or contaminated with dust particles. This can completely compromise the airtightness of the explosion-proof valve. If the piston spring explosion-proof valve is designed with a high opening pressure, it may not open in the early stages of thermal runaway. Furthermore, when the pressure inside the battery pack decreases slightly, the valve opening will become smaller or even completely closed, resulting in a slow explosive exhaust rate and weak pressure relief capacity. This delay in pressure relief can cause bulging of the battery pack casing. This piston spring explosion-proof valve poses significant uncertainty to the safety of new energy vehicles.

[0034] Compared with the above-mentioned piston spring explosion-proof valve, this embodiment provides a one-way valve 4 with low opening pressure and good air tightness. The one-way valve 4 is an umbrella valve, which is made of elastic material and includes a valve stem 41, an umbrella-shaped valve cover 42 and a limiting portion 43. One end of the valve stem 41 is connected to the umbrella-shaped valve cover 42, and the other end is connected to the limiting portion 43. The base 1 is correspondingly provided with a mounting hole 13, and a plurality of second pressure relief holes 12 arranged around the mounting hole 13 are provided around the mounting hole 13. The second pressure relief holes 12 are fan-shaped. The design and arrangement of the second pressure relief holes 12 make full use of space and help improve the pressure relief efficiency. The valve stem 41 of the umbrella valve is inserted into the mounting hole 13, and the edge of the end face of the umbrella-shaped valve cover 42 facing the valve stem 41 elastically abuts against the outer surface of the base 1, and the end face of the limiting portion 43 facing the valve stem 41 abuts against the inner surface of the base 1. Compared with the piston spring explosion-proof valve, the umbrella valve of this embodiment eliminates the spring structure. The umbrella-shaped valve cover 42 is pressed onto the outer surface of the base 1 by its own material properties, and has a sufficient pressing area to ensure airtightness with the base 1 to prevent water from entering. Its opening pressure depends on the hardness of the umbrella valve material.

[0035] In order to facilitate the assembly of the umbrella valve, the mounting hole 13 of this embodiment is configured as a tapered hole whose aperture shrinks from the outer surface to the inner surface of the base 1. Correspondingly, the outer peripheral wall of the end of the limiting portion 43 of the one-way valve 4 away from the valve stem 41 is configured as a guide inclined surface 431 that cooperates with the mounting hole 13 so that the limiting portion 43 can pass through the mounting hole 13.

[0036] In this embodiment, the one-way valve 4, at least its umbrella-shaped valve cover 42, is made of an elastic material to ensure that the second pressure relief hole 12 can be opened and closed. Using an elastic material to form the stop block facilitates assembly of the one-way valve 4 onto the base 1. The entire one-way valve 4 is integrally molded from an elastic material, simplifying processing. The one-way valve 4 can be made of materials such as silicone, natural rubber, nitrile rubber, or thermoplastic elastomer.

[0037] In order to prevent the one-way valve 4 from being unable to open due to interference from external parts, the base 1 of this embodiment forms an outwardly protruding convex ring 14 on the outside of the one-way valve 4. The convex ring 14 is higher than the one-way valve 4 and encloses the air vent 21 and the mounting hole 13 therein to ensure the effectiveness of the one-way valve 4 in opening the second pressure relief hole 12.

[0038] The base 1 of this embodiment is circumferentially embedded with a number of metal pre-embedded nuts 16 to secure the explosion-proof valve to the energy storage battery pack housing and prevent fatigue loosening. A sealing ring 17 protruding from the inner surface of the base 1 is embedded in the inner surface of the base 1 to ensure an airtight seal between the explosion-proof valve and the energy storage battery pack housing to prevent water ingress. The base 1 can be made of materials such as flame-retardant reinforced PBT, flame-retardant reinforced PA, flame-retardant reinforced PC, or flame-retardant reinforced PPS. Flame-retardant reinforcement refers to the addition of flame retardants and reinforcing materials to the material to improve the material's flame retardant and mechanical properties. PA+30GF flame-retardant engineering plastics are preferred.

[0039] The energy storage battery explosion-proof valve of this embodiment operates as follows: When the battery is operating normally, the pressure differential between the inside and outside of the battery pack is balanced through the waterproof and breathable membrane 3. In the early stages of thermal runaway, when the temperature of the battery pack has not yet reached the melting point of the thermoplastic membrane 2, pressure is primarily released through the second pressure relief hole 12 by opening the one-way valve 4. When the battery pack experiences severe thermal runaway, the high temperature generated reaches the melting point of the thermoplastic membrane 2, causing it to melt and the waterproof and breathable membrane 3 to fall off. The first pressure relief hole 11 opens, allowing the heat inside the battery pack to be quickly released, thereby preventing the battery pack from exploding.

[0040] Although the present invention has been specifically shown and described in conjunction with the preferred embodiments, it should be understood by those skilled in the art that various changes in form and details of the present invention are within the scope of protection of the present invention without departing from the spirit and scope of the present invention as defined in the appended claims.

Claims

1. An explosion-proof valve for energy storage batteries, characterized in that: include: The base body (1) is provided with a first pressure relief hole (11) and a second pressure relief hole (12); A thermoplastic film (2) is sealed and connected to the base body (1) and covers the first pressure relief hole (11); the thermoplastic film (2) is provided with a vent hole (21); the orthographic projection of the vent hole (21) on the base body (1) is located within the first pressure relief hole (11); A waterproof breathable membrane (3) is sealed and connected to the thermoplastic membrane (2) and covers the breathable hole (21); A one-way valve (4) is connected to the base body (1) and is used to open and close the second pressure relief hole (12).

2. The explosion-proof valve for energy storage battery according to claim 1, characterized in that: The orthographic projection of the waterproof and breathable membrane (3) on the base (1) is located within the first pressure relief hole (11).

3. The explosion-proof valve for energy storage battery according to claim 1, characterized in that: The base (1) is provided with a mounting hole (13); The one-way valve (4) comprises: a valve stem (41), an umbrella-shaped valve cover (42) connected to one end of the valve stem (41), and a limiting portion (43) connected to the other end of the valve stem (41), wherein the umbrella-shaped valve cover (42) is made of elastic material, and the valve stem (41) is inserted into the mounting hole (13), and the end face edge of the umbrella-shaped valve cover (42) facing the valve stem (41) elastically abuts against the outer surface of the base (1), and the end face of the limiting portion (43) facing the valve stem (41) abuts against the inner surface of the base (1).

4. The explosion-proof valve for energy storage battery according to claim 3, characterized in that: The mounting hole (13) is configured as a tapered hole whose diameter shrinks from the outer surface to the inner surface of the base body (1); An outer peripheral wall of one end of the limiting portion (43) away from the valve stem (41) is configured as a guide slope (431).

5. The explosion-proof valve for energy storage battery according to claim 3, characterized in that: The base body (1) is provided with a plurality of second pressure relief holes (12) arranged around the mounting hole (13) along the circumference of the mounting hole (13), and the second pressure relief holes (12) are fan-shaped.

6. The explosion-proof valve for energy storage battery according to claim 3, characterized in that: The base (1) is formed with a convex ring (14) protruding outward on the outside of the one-way valve (4), and the air vent (21) and the mounting hole (13) are located inside the convex ring (14).

7. The explosion-proof valve for energy storage battery according to claim 1, characterized in that: A hollow support member (15) connected to the base body (1) is provided in the first pressure relief hole (11), and the hollow support member (15) is used to support the thermoplastic membrane (2) and / or the waterproof breathable membrane (3).

8. The explosion-proof valve for energy storage battery according to claim 1, characterized in that: The base body (1) is embedded with a plurality of metal pre-embedded nuts (16) along the circumferential direction, and the inner surface of the base body (1) is embedded with a sealing ring (17) protruding from the inner surface of the base body (1).

9. The explosion-proof valve for energy storage batteries according to any one of claims 1 to 8, characterized in that: The melting point of the thermoplastic film (2) is 100-260°C.

10. The explosion-proof valve for energy storage batteries according to any one of claims 1 to 8, characterized in that: The one-way valve (4) is made of one of silicone, natural rubber, nitrile rubber and thermoplastic elastomer; The waterproof and breathable membrane (3) is made of e-PTFE; The thermoplastic film (2) is made of one of PP, PA, PE, ABS, TPU and PVDF; The substrate (1) is made of one of flame retardant reinforced PBT, flame retardant reinforced PA, flame retardant reinforced PC and flame retardant reinforced PPS.

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