Built-in flame-retardant device for battery cell of liquid battery

Abstract

The invention relates to the field of organic solvent electrolyte battery cells, in particular to a built-in flame-retardant device for a liquid battery cell, the flame-retardant device is arranged in the liquid battery cell, the top of the flame-retardant device is in contact with electrolyte, and the bottom of the flame-retardant device is connected with the bottom of the battery cell; a storage device for storing a fire extinguishing agent is arranged in the flame-retardant device, a constant-pressure blasting structure is arranged at the top of the storage device, and an anti-explosion structure is arranged at the bottom of the storage device; and the constant-pressure blasting structure is used for actively blasting under the condition that the internal part of the battery cell reaches a preset pressure, and discharging the fire extinguishing agent in the storage device, so that the fire extinguishing agent is mixed with the electrolyte. Compared with the prior art, the flame-retardant device is additionally arranged in the battery cell, so that the electrolyte and the fire extinguishing agent are mixed in advance before the battery is on fire and deflagration, and the effect of controlling the on fire and deflagration of the battery cell from the source is achieved.

Description

Technical Field

[0001] The present invention relates to the field of organic solvent electrolyte battery cells, and particularly to a flame retardant device built into a liquid battery cell. Background Art

[0002] For liquid battery cells, organic solvents are often used as key components of the electrolyte. However, such battery cells have obvious safety hazards. When encountering extreme situations such as extrusion and puncture, they are very likely to catch fire or even explode. The organic electrolyte inside the organic solvent liquid battery cell is highly flammable, and the battery itself belongs to a high-energy-density electrochemical system. Once the thermal runaway process starts, it is difficult to reverse, resulting in incalculable losses, such as the complete destruction of the vehicle and energy storage device itself, casualties and property losses caused by the spread of fire, and serious harm to the environment. Although existing external fire extinguishing devices can control the fire in a short time, they cannot fundamentally solve the problem, and the fire will soon reignite.

[0003] Large-scale power battery packs are widely used in power systems, and energy storage devices are also widely used. However, their internal structure is complex, and the intrinsic safety of the battery cells cannot be achieved. To ensure the safety of the battery pack, a large number of external fire extinguishing devices and materials have to be relied on. As a result, the complexity of technology implementation and production costs have increased significantly.

[0004] Patent CN114870299A discloses a battery pack fire extinguishing system with dual electronic and mechanical controls, including a housing, an electronic fire extinguishing device, a controller, and a mechanical fire extinguishing device. The mechanical fire extinguishing device includes a second storage container and a second nozzle connected to the bottom of the second storage container. A nozzle fusible body blocking the nozzle of the second nozzle is provided inside the housing. The nozzle fusible body melts when the temperature inside the housing reaches a second set temperature, so that the fire extinguishing agent in the second storage container is sprayed into the housing from the nozzle of the second nozzle. This patent sprays the fire extinguishing agent when the temperature sensor detects too high temperature or the high temperature melts the nozzle fusible body of the second nozzle to achieve the fire extinguishing effect. However, this system is more suitable for large battery packs rather than relatively small lithium-ion batteries.

[0005] Patent CN116031529A discloses a battery device and a motor vehicle with a fire extinguishing device. The battery device includes a fire extinguishing device having at least one fire extinguishing unit. The at least one fire extinguishing unit is arranged in a battery housing and includes a housing element and a fire extinguishing agent. The fire extinguishing agent is arranged in a cavity of the housing element. The fire extinguishing unit has an explosion mechanism designed to cause the explosion of the housing element and the release of the fire extinguishing agent in the form of an aerosol in the presence of a predetermined fire state generated when at least one battery element catches fire. However, the judgment criteria for the fire state in this invention are not specific, and simply relying on the explosion to damage the housing element may generate metal fragments, causing secondary damage to the battery elements.

[0006] At present, lithium-ion batteries cannot achieve reliable intrinsic safety. When a single battery cell undergoes thermal runaway, it will trigger a huge chain reaction, causing serious losses. Currently, there is still a lack of practical, convenient and effective methods to achieve the intrinsic safety of battery cells, and only rely on external fire extinguishing devices for reluctant control. However, this method is far from enough in the face of the out-of-control situation of large-scale power batteries or energy storage devices. Summary of the Invention

[0007] (I) Technical Problems to be Solved The purpose of the present invention is to provide a flame retardant device built into a liquid battery cell to solve at least one of the above problems, so as to overcome the problem that in the case of abuse, when thermal runaway occurs, the battery cell explodes and burns, and only relies on external fire extinguishing devices for reluctant control. By adding a flame retardant device to the battery cell, the electrolyte and the fire extinguishing agent are premixed before the battery catches fire and explodes, achieving the effect of controlling the fire and explosion of the battery cell at the source.

[0008] (II) Technical Solutions The purpose of the present invention is achieved through the following technical solutions: To solve the above technical problems, the present invention provides a flame retardant device built into a liquid battery cell. The flame retardant device is arranged inside the liquid battery cell. The top of the flame retardant device is in contact with the electrolyte, and the bottom is connected to the bottom of the battery cell. A storage device is arranged in the flame retardant device to store the fire extinguishing agent. A constant pressure bursting structure is arranged at the top of the storage device, and an explosion-proof structure is arranged at the bottom of the storage device. The constant pressure bursting structure is used to actively burst under the condition that the internal pressure of the battery cell reaches a predetermined pressure, discharging the fire extinguishing agent in the storage device, so that the fire extinguishing agent is mixed with the electrolyte.

[0009] Further, after the flame retardant device is manufactured, it is placed at the bottom of the battery cell during the battery assembly process, and other battery manufacturing processes do not need to be changed.

[0010] Furthermore, the constant-pressure bursting structure is set as a metal bursting disc with a thin center and thick edges, and a V-shaped groove is arranged on the center surface of the constant-pressure bursting structure. The metal bursting disc at the V-shaped groove on the center surface of the constant-pressure bursting structure is the thinnest. Therefore, when the constant-pressure bursting structure ruptures, the metal bursting disc is more inclined to tear along the V-shaped groove to both sides, forming a stable tear rather than bursting fragments, so that the fire extinguishing agent is discharged from both ends of the long axis of the battery cell, avoiding explosion and injury to adjacent battery cells in the vertical direction. Moreover, the opening formed by the tearing of the metal bursting disc is a linear gap, ensuring that the fire extinguishing agent is ejected along the gap and accelerating the mixing of the fire extinguishing agent and the electrolyte.

[0011] Furthermore, the center thickness of the metal bursting disc is 30%-50% of the edge thickness. The metal bursting disc with a thin center and thick edges enables the constant-pressure bursting structure to quickly crack to both sides when subjected to pressure deformation.

[0012] Furthermore, the material of the metal bursting disc is the same as that of the battery housing.

[0013] Furthermore, the material of the metal bursting disc is steel alloy or aluminum alloy.

[0014] Furthermore, the steel alloy selected is nickel-plated steel. The nickel-plated steel contains a high proportion of nickel and has an extremely low corrosion rate in the organic electrolyte, and is not prone to current corrosion during the charging and discharging process of the battery; the nickel-based alloy has stable mechanical properties. In the case of battery thermal runaway, the nickel-based alloy can maintain high strength, ensuring that the metal bursting disc tears only under pressure triggering, rather than failing due to high-temperature softening.

[0015] Furthermore, the alloy can be a shape memory alloy, especially a nickel-titanium-copper ternary alloy or a nickel-titanium-niobium ternary alloy. The shape memory alloy preset the phase change temperature by adjusting the composition, making the end temperature of its austenite phase change consistent with the temperature of battery thermal runaway. When the internal temperature of the battery reaches the threshold, the shape memory alloy undergoes shape recovery deformation and actively tears the housing along the V-shaped groove to release the fire extinguishing agent.

[0016] Furthermore, the explosion-proof structure includes an explosion-proof valve and a fire extinguishing agent injection port, and a honeycomb-shaped flow guide net is arranged in the fire extinguishing agent injection port. The purpose of setting the explosion-proof valve in the explosion-proof structure is to prevent the flame retardant device from spraying out under non-battery thermal runaway conditions.

[0017] If the battery pressure relief valve is set at the bottom of the battery cell, in the case where the flame retardant device is set at the inner bottom of the battery cell, if the pressure relief valve is not set at the bottom of the flame retardant device, then the flame retardant device will cause the battery to be unable to discharge high-temperature gases and ejecta from the original battery pressure relief valve, resulting in more serious consequences. Therefore, a pressure relief valve is set at the bottom of the flame retardant device, enabling the battery to be discharged according to the original design, minimizing the change in the battery structure caused by adding this flame retardant device and the resulting additional effects.

[0018] The aperture of the honeycomb-shaped diversion port is ≤ 0.5 mm, which can filter out some particulate matters brought in during the filling of the fire extinguishing agent, prevent the filling port of the fire extinguishing agent from being blocked by the particulate matters in the fire extinguishing agent, and improve the filling efficiency.

[0019] Further, the fire extinguishing agent is a fluorine-containing fire extinguishing agent, including any one of perfluoromethyl hexanone, perfluoropolyether, fluorinated ketone, and heptafluoropropane. Fluorine-containing fire extinguishing agents (such as perfluoromethyl hexanone, perfluoropolyether, fluorinated ketone, etc.) usually do not undergo significant chemical reactions with the organic electrolyte of lithium-ion batteries (such as carbonate solvents) and can be used for the thermal runaway protection of lithium-ion batteries.

[0020] Further, the pressure threshold of the constant-pressure bursting structure is less than the pressure threshold of the pressure relief port of the battery cell. After the constant-pressure bursting structure is pressured and bursts, the fluorine-containing fire extinguishing agent in the storage device is mixed with the electrolyte inside the cell, and the battery continues to experience thermal runaway. The mixed liquid of the electrolyte and the fire extinguishing agent is synchronously discharged when it reaches the bursting pressure at the pressure relief port of the cell. Since the electrolyte and the fire extinguishing agent have been pre-mixed, the volume ratio of the fire extinguishing agent in the discharged material reaches 30 - 50%, forming an organic aerosol protective layer that inhibits deflagration.

[0021] Further, the volume ratio of the fire extinguishing agent in the storage device to the electrolyte in the battery cell is (5 - 15):(85 - 95).

[0022] Further, the flame retardant device is connected to the bottom of the battery cell by any one of the connection methods of bonding, welding, clamping, and threaded connection.

[0023] Furthermore, the flame retardant device is fixed to the bottom of the cell by laser welding.

[0024] Further, the liquid battery includes any one of a cylindrical liquid battery, a square liquid battery, and a blade liquid battery.

[0025] Further, the cross-sectional area of the flame retardant device is smaller than the area of the inner bottom of the cell. This facilitates the installation of the flame retardant device at the inner bottom of the cell.

[0026] Further, the flame retardant device is provided as one or more. When multiple flame retardant devices are provided, the multiple flame retardant devices are connected to each other.

[0027] Further, when the battery is a square battery or a blade battery, multiple flame retardant devices are provided, and the multiple flame retardant devices are connected in parallel. The multiple flame retardant devices achieve coordinated release of the fire extinguishing agent through a parallel pipeline.

[0028] The flame retardant device can adopt a modular combination design. In a square or blade battery, 2 - 4 flame retardant devices with a diameter ≤ 20 mm are configured, and each flame retardant device achieves coordinated release of the fire extinguishing agent through a parallel pipeline.

[0029] (3) Beneficial Effects Compared with the prior art, the present invention has the following advantages: (1) A flame retardant device is provided inside the battery cell. The flame retardant device is equipped with a constant pressure bursting device. When the internal pressure of the battery cell reaches the set value, the constant pressure bursting device will actively burst, releasing the fluorine-containing fire extinguishing agent pre-filled in the flame retardant device. The released fluorine-containing fire extinguishing agent is fully mixed with the electrolyte inside the cell to form a uniformly dispersed mixed liquid. When the pressure relief port of the cell reaches the bursting pressure, the mixed liquid will be discharged from the cell together with the organic aerosol. Since the aerosol is filled with an efficient fluorine-containing fire extinguishing agent, it can effectively prevent the occurrence of deflagration of the battery cell.

[0030] (2) The present invention uses a nickel-based metal as the metal bursting disc of the directional bursting structure. The nickel-based alloy contains a high proportion of nickel, has an extremely low corrosion rate in the organic electrolyte, and is not prone to current corrosion during the charging and discharging process of the battery; the mechanical properties of the nickel-based alloy are stable, and the nickel-based alloy can maintain high strength under the condition of battery thermal runaway, ensuring that the metal bursting disc tears only under pressure triggering, rather than failing due to high-temperature softening; the nickel-titanium-copper ternary alloy or nickel-titanium-niobium ternary alloy in the nickel-based alloy is a shape memory alloy, and the phase change temperature can be preset by adjusting the composition. When the internal temperature of the battery reaches the threshold value, the shape memory alloy undergoes shape recovery deformation and actively tears the shell along the V-shaped groove to release the fire extinguishing agent.

[0031] (3) The present invention uses a fluorine-containing fire extinguishing agent as the flame retardant liquid. Taking perfluoropentanone as an example, perfluoropentanone molecules will capture free radical ions at high temperatures, interrupt the chain reaction of combustion, thereby inhibiting the development of the fire. When perfluoropentanone is ejected, it will quickly vaporize, absorb a large amount of heat, reduce the temperature of the fire field, and further inhibit the fire. Therefore, the battery cell of the present invention ensures that the fire extinguishing agent can quickly and effectively extinguish the flame during thermal runaway and prevent the spread of the fire.

[0032] (4) The present invention can be directly installed at the bottom inside the battery cell during the battery assembly process, has a processing process independent of battery manufacturing, can greatly save processing and assembly time, and the structure and shape of the battery do not need to be changed at all. The assembly cost is low, and the current standard general manufacturing and use methods are continued. Only a small number of failed cells need to be replaced to achieve the safe use of the battery, avoiding huge losses to personnel, property, and the environment. Description of the Drawings

[0033] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0034] Figure 1 This is a cross-sectional view of a flame retardant device built into a liquid battery cell of the present invention in the battery; Figure 2 This is a three-dimensional diagram of a flame retardant device built into a liquid battery cell of the present invention; Figure 3 This is a side view of a flame retardant device built into a liquid battery cell of the present invention; Figure 4 This is a bottom view of a flame retardant device built into a liquid battery cell of the present invention; In the figure: 1-flame retardant device; 2-constant pressure blasting structure; 21-V-shaped groove; 3-storage device; 4-explosion-proof structure; 41-explosion-proof valve; 42-fire extinguishing agent injection port. DETAILED DESCRIPTION

[0035] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0036] The following describes the embodiments of the present application through specific examples, and those skilled in the art can easily understand other advantages and effects of the present application from the contents disclosed in this specification. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. The present application can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present application. It should be noted that, in the absence of conflict, the features in the following embodiments and embodiments can be combined with each other. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without making creative work are within the scope of protection of this application.

[0037] It should be noted that various aspects of the embodiments within the scope of the appended claims are described below. It should be apparent that the aspects described herein can be embodied in a wide variety of forms, and any specific structure and / or function described herein is merely illustrative. Based on this application, it should be understood by those skilled in the art that an aspect described herein can be implemented independently of any other aspect, and two or more of these aspects can be combined in various ways. For example, any number and aspect described herein can be used to implement an apparatus and / or practice a method. In addition, other structures and / or functionalities other than one or more of the aspects described herein can be used to implement this apparatus and / or practice this method.

[0038] It should also be noted that the diagrams provided in the following embodiments only illustrate the basic concept of the present application in a schematic manner. The diagrams only show the components related to the present application, rather than being drawn according to the number, shape, and size of the components in actual implementation. The type, quantity, and proportion of each component in actual implementation can be arbitrarily changed, and the component layout type may also be more complex.

[0039] In addition, in the following description, specific details are provided to facilitate a thorough understanding of the examples. However, those skilled in the art will understand that the examples can be practiced without these specific details.

[0040] The following describes the technical solutions provided by each embodiment of the present application with reference to the accompanying drawings. Embodiment 1

[0041] Refer to Figures 1 to 3 , the present invention provides a flame retardant device built into a liquid battery cell. The flame retardant device 1 is disposed inside the liquid battery cell. The top of the flame retardant device 1 is in contact with the electrolyte, and the bottom is connected to the bottom of the battery cell. The flame retardant device 1 is fixed to the bottom of the cell by laser welding. The cross-sectional area of the flame retardant device 1 is smaller than the area of the bottom inside the cell.

[0042] As Figure 2 shown, a storage device 3 for storing a fire extinguishing agent is provided in the flame retardant device 1. A constant pressure bursting structure 2 is provided at the top of the storage device 3, and an explosion-proof structure 4 is provided at the bottom of the storage device 3.

[0043] As Figure 2 ]>shown, the constant pressure bursting structure 2 is set as a steel alloy metal bursting disc with a thin center and a thick edge. A V-shaped groove 21 is provided on the center surface of the constant pressure bursting structure 2. The constant pressure bursting structure 2 is used to actively burst under the condition that the internal pressure of the battery cell reaches a predetermined pressure, discharging the fire extinguishing agent in the storage device 3 so that the fire extinguishing agent is mixed with the electrolyte. The edge thickness of the constant pressure bursting structure 2 is 50 μm, the thickness of the central area is 10 - 15 μm, and the depth of the V-shaped groove 21 is 5 μm, which is formed by laser etching.

[0044] As Figure 3 shown, the explosion-proof structure 4 includes an explosion-proof valve 41 and a fire extinguishing agent injection port 42. A honeycomb-shaped flow guiding net is provided in the fire extinguishing agent injection port 42, and the aperture of the honeycomb-shaped flow guiding port is ≤ 0.5 mm.

[0045] After the flame retardant device 1 is manufactured, it is placed at the bottom of the battery cell during the battery assembly process, and other battery manufacturing processes do not need to be changed.

[0046] The fire extinguishing agent is set as the fluorine-containing fire extinguishing agent perfluoromethyl hexanone.

[0047] The pressure threshold of the constant pressure bursting structure 2 is less than the pressure threshold of the pressure relief port of the battery cell.

[0048] The volume ratio of the fire extinguishing agent in the storage device 3 to the electrolyte in the battery cell is 15:85.

[0049] For the same or similar parts among the various embodiments in this specification, reference can be made to each other. Each embodiment focuses on the differences from other embodiments.

[0050] As described above, the above are only specific embodiments of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed in the present application should be covered by the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A flame retardant device built into a liquid battery cell, characterized in that, The flame retardant device (1) is arranged inside the liquid battery cell. The top of the flame retardant device (1) is in contact with the electrolyte, and the bottom is connected to the bottom of the battery cell. A storage device (3) for storing a fire extinguishing agent is arranged in the flame retardant device (1). A constant pressure bursting structure (2) is arranged at the top of the storage device (3), and an explosion-proof structure (4) is arranged at the bottom of the storage device (3). The constant pressure bursting structure (2) is used to actively burst under the condition that the internal pressure of the battery cell reaches a predetermined pressure, and discharge the fire extinguishing agent in the storage device (3), so that the fire extinguishing agent is mixed with the electrolyte.

2. The flame retardant device built into the liquid battery cell according to claim 1, wherein, The constant pressure bursting structure (2) is set as a metal bursting disc with a thin center and a thick edge. A V-shaped groove (21) is arranged on the center surface of the constant pressure bursting structure (2).

3. The flame retardant device built into the liquid battery cell according to claim 2, characterized in that, The material of the metal bursting disc is the same as that of the battery housing.

4. The flame retardant device built into the liquid battery cell according to claim 3, characterized in that, The pressure threshold of the constant pressure bursting structure (2) is less than the pressure threshold of the pressure relief port of the battery cell.

5. The flame retardant device built into the liquid battery cell according to claim 4, wherein, The volume ratio of the fire extinguishing agent in the storage device (3) to the electrolyte in the battery cell is (5 - 15):(85 - 95).

6. The flame retardant device built into the liquid battery cell according to claim 5, wherein, The explosion-proof structure (4) includes an explosion-proof valve (41) and a fire extinguishing agent injection port (42). A honeycomb-shaped flow guiding net is arranged in the fire extinguishing agent injection port (42).

7. The flame retardant device built into the liquid battery cell according to claim 6, characterized in that, The fire extinguishing agent is a fluorine-containing fire extinguishing agent, including any one of perfluoromethyl hexanone, perfluoropolyether, fluorinated ketone, and heptafluoropropane.

8. A flame retardant device built into a liquid battery cell as claimed in claim 7, characterized in that, The flame retardant device (1) is connected to the bottom of the battery cell by any one of bonding, welding, clamping, and threaded connection.

9. The flame retardant device built into the liquid battery cell according to claim 8, characterized in that, The cross-sectional area of the flame retardant device (1) is smaller than the area of the bottom inside the battery cell.

10. A flame retardant device built into a liquid battery cell as claimed in claim 9, characterized in that, The flame retardant device (1) is set to be one or more. When multiple flame retardant devices (1) are provided, the multiple flame retardant devices (1) are connected to each other.

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