A mixed gas fire extinguishing method for extinguishing a ternary battery module

Abstract

The present application relates to fire extinguishing material technical field, specifically, a kind of mixed gas fire extinguishing method for extinguishing ternary battery module, container one is provided with helium and nitrogen one with mixing ratio of 6:4, container two is provided with perfluorohexanone and nitrogen two as driving gas and partially dissolved in perfluorohexanone, the volume ratio of perfluorohexanone and nitrogen two in container two is 77% and 23% respectively;With the way of container one first starting, container two after starting, the gas in the two is mixed in ternary lithium battery module for fire extinguishing, by the inert gas combined with spraying synergistic mechanism configured by helium combined with nitrogen, the physical and chemical characteristics of each gas are used, high, medium and low overlapping concentration distribution is formed, oxygen concentration is reduced to degrade flame and heat absorption cooling in turn, chemical chain reaction is inhibited, the synergistic comprehensive effect of multiple fire extinguishing mechanism is formed, a feasible solution is provided for solving ternary lithium battery fire, and the safety of new energy vehicle passengers is guaranteed.

Description

Technical Field

[0001] This invention relates to the field of fire extinguishing materials technology, specifically a method for extinguishing mixed gas fires involving ternary lithium battery modules. Background Technology

[0002] With the rapid development of new energy vehicles, their driving range has become a crucial standard for evaluating their development level. To meet the ever-increasing range demands of new energy vehicles, ternary lithium batteries are widely used as power batteries. However, the energy density of ternary lithium batteries continues to increase. When fires occur due to thermal runaway of the battery module caused by collisions, low battery quality, aging lithium dendrites, or overcharging and discharging, the fires are extremely powerful, generating temperatures exceeding 1000 degrees Celsius. Current in-vehicle fire extinguishing technologies are ineffective in extinguishing such fires, thus posing a significant threat to the driving safety of new energy vehicles and the safety of their occupants.

[0003] Existing fire extinguishing technologies for battery fires are divided into gas-based and water-based extinguishing technologies. The former primarily uses chemical gases such as perfluorohexanone and heptafluoropropane, and inert gases such as carbon dioxide and nitrogen (including liquid nitrogen) to spray extinguishing agents into the interior of the battery module, or uses water-based extinguishing technologies. The latter, water-based extinguishing technologies, mainly use fine water mist, water spray, or water immersion to spray fire extinguishing agents onto the exterior of the battery module. However, both of these fire extinguishing technologies have some shortcomings when dealing with ternary lithium battery fires, specifically: First, because ternary lithium batteries have extremely high energy density, once a fire occurs, the temperature inside the power battery box is much higher than that of lithium iron phosphate batteries that use electrochemical energy storage, reaching a maximum temperature of 1200-1800℃. Meanwhile, chemical gaseous fire extinguishing agents such as perfluorohexanone and heptafluoropropane will decompose at temperatures above 600℃ and completely lose their fire extinguishing performance, making them unable to cope with ternary lithium battery fires, especially for the large power battery boxes with multiple modules and high energy density used in new energy passenger vehicles.

[0004] Secondly, due to the unique characteristics of lithium battery fires, the extremely high temperatures and the release of large amounts of flammable gases cause the fire to spread rapidly and even explode. If one heating element within a lithium battery module goes out of control, all the cells can ignite. This process not only thermally decomposes the battery, releasing flammable and explosive gases, but also releases oxygen that supports combustion. The electrolyte in ternary lithium batteries releases even more oxygen. Therefore, inert gases such as carbon dioxide and nitrogen (including liquid nitrogen), which smother the fire by reducing oxygen concentration, become ineffective when more oxygen is released and the oxygen concentration inside the battery box rises above 16%. These methods are insufficient to combat fires involving ternary lithium batteries in new energy passenger vehicles. Furthermore, passenger vehicles cannot carry large containers of inert gas extinguishing agents, significantly limiting their effectiveness.

[0005] Furthermore, as general mobile vehicles, new energy passenger vehicles cannot carry large amounts of water for firefighting. Limited water-based extinguishing agents are ineffective, and too much water-based extinguishing agent filling the battery compartment may absorb heat, causing it to expand and burst. This would result in the leakage of burning battery electrolyte, allowing the fire to spread and become uncontrollable within the compartment. Therefore, water-based fire extinguishing systems are also unsuitable for firefighting operations that cannot handle fires involving passenger vehicle power batteries.

[0006] Based on the above reasons, this invention designs a mixed gas fire extinguishing method for extinguishing ternary lithium battery modules. It utilizes a novel inert gas mixture of helium and nitrogen in a specific ratio, combined with a two-jet synergistic mechanism involving perfluorohexanone and nitrogen as the driving gas, partially dissolved in perfluorohexanone. By leveraging the physicochemical properties of each gas, a high-, medium-, and low-concentration overlapping distribution is formed. This first rapidly reduces the oxygen concentration in the combustion zone, immediately extinguishing the open flame. Then, through flame degradation, suffocation, free radical capture, and blocking of the flame chain reaction, a synergistic effect of multiple fire extinguishing mechanisms is achieved. This provides a practical solution for ternary lithium battery fires, ensuring the safety of passengers in new energy vehicles. Summary of the Invention

[0007] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a mixed gas fire extinguishing method for extinguishing ternary lithium battery modules. This method utilizes a novel inert gas mixture of helium and nitrogen in a specific ratio, combined with perfluorohexanone and nitrogen (partially dissolved in perfluorohexanone) as the driving gas, to create a synergistic two-jet mechanism. By leveraging the physicochemical properties of each gas, a high-low concentration distribution is formed, rapidly reducing the oxygen concentration in the combustion zone and immediately extinguishing the open flame. Furthermore, through flame degradation, suffocation, free radical capture, and disruption of the flame chain reaction, a synergistic effect of multiple fire extinguishing mechanisms is achieved. This provides a practical solution for ternary lithium battery fires and ensures the safety of passengers in new energy vehicles.

[0008] A mixed gas fire extinguishing method for extinguishing ternary battery modules includes a container one and a container two. The container one contains helium and nitrogen gas one in a mixing ratio of 6:4. The container two contains perfluorohexanone and nitrogen gas two as a driving gas that is partially dissolved in perfluorohexanone. The volume ratio of perfluorohexanone to nitrogen gas two in the container two is 77% and 23%, respectively.

[0009] The gas inside each container is mixed in a ternary lithium battery module to extinguish the fire, with container one starting first and container two starting later.

[0010] The actual values ​​of the extinguishing concentration of the gas in Container 1 and Container 2 were obtained based on theoretical research and testing experiments using a flame cup burner and a lithium battery combustion test chamber.

[0011] The design value for the extinguishing concentration of the gas in container one and container two is: actual extinguishing concentration + actual extinguishing concentration × 30%.

[0012] The actual extinguishing concentration of the gas in container one is 45%; the actual extinguishing concentration of the gas in container two is 20%.

[0013] The calculation formulas for the design values ​​of fire extinguishing or inertia dosage of helium and nitrogen gas I in container one and nitrogen gas II in container two are as follows: ; The constant of helium Here, T is the numerical value of the temperature variable; The constant of nitrogen Here, T is the numerical value of the temperature variable; ; Where Q is the design value of total flooding extinguishing or degradation dosage, in kg; K is the altitude correction factor for the protected area; H is the altitude, in meters; s is the vapor specific volume of helium or nitrogen at the lowest expected temperature in the protected area when the pressure is 101.325 kPa, in cubic meters per second. 3 / kg; T represents the minimum expected temperature of the protected area, in °C; C represents the design value of the extinguishing concentration or the design value of the chemical dosage for the protected area, in °C.

[0014] The formula for calculating the design value of the fire extinguishing or inactivation dosage of perfluorohexanone in container two is as follows: ; ; ; Where Q is the design value of total flooding extinguishing or degradation dosage, in kg. K is the altitude correction factor for the protected area; H is the altitude, in meters; s is the vapor specific volume of perfluorohexanone at the lowest expected temperature in the protected area at a pressure of 101.325 kPa, in cubic meters per second. 3 / kg; T represents the minimum expected temperature of the protected area, in °C; C represents the design value of the fire extinguishing concentration or the design value of the degradation concentration of the protected area, in °C.

[0015] The formula for calculating the container pressure of container one is: ; Where P is the container pressure (in L); V is the extinguishing agent volume; M is the extinguishing agent mass (in kg); n is the molar mass = V / 22.4; and T is the temperature. V represents the volume of the extinguishing agent, specifically: V1 = M / 0.1786 × 1000; V1 is the volume of helium gas; V2 = M / 1.25 × 1000; V2 is the volume of nitrogen gas 1; R is the ideal gas constant. When the units of P, V, n, and T are atm, L, mol, and K, respectively, the value of R is 8.314, and the unit is kPa. a is 0.33615, b is 0.02976; The pressure in container two is calculated based on the volumetric proportion of the driving gas from nitrogen two, specifically as follows: ; Where P is the container pressure (L); V is the extinguishing agent volume (L); and M is the extinguishing agent mass (kg). n is the molar mass = V / 22.4; T is the temperature; V represents the volume of the extinguishing agent, specifically: V 氮 =M / 1.25×1000; R is the ideal gas constant. When the units of P, V, n, and T are atm, L, mol, and K, respectively, the value of R is 8.314, and the unit is kPa. a is 1.3900, and b is 0.0391.

[0016] Compared with existing technologies, it has the following advantages: This invention utilizes three gases to synergistically reduce oxygen concentration, asphyxiate, endothermize and cool, and capture free radicals to interrupt the flame chain reaction, thereby effectively inhibiting combustion. In other words, it achieves highly efficient fire extinguishing through its four fire-extinguishing mechanisms: 1) Reduce oxygen concentration: (The oxygen concentration in container one is lower than the oxygen concentration in container two.) The main gas in container 1 is He+N2 inert gas, supplemented by FK chemical gas in container 2. The oxygen concentration is reduced to the level that suffocates the flame, and the high temperature in the combustion zone also drops rapidly, providing a prerequisite for further suppressing combustion.

[0017] 2) Physical heat absorption and cooling: mainly using He and FK (FK-5-1-12) with large heat capacity, and supplemented by N2.

[0018] 3) Chemical decomposition endothermic cooling: FK undergoes thermal decomposition at high temperatures, carrying away a certain amount of temperature (decomposition enthalpy).

[0019] 4) Chemical chain reaction of chemical decomposition inhibits combustion free radicals: FK's F and C thermal decomposition free radical effect.

[0020] The synergistic effect of ternary gases also includes complementing each other's shortcomings and more effectively exerting their respective fire extinguishing mechanisms. With a more reasonable design, it can extinguish ternary lithium battery fires with lower dosage and cost and greater efficiency. Based on the physical and chemical properties of each gas, it forms a high, medium and low overlapping concentration distribution, successively reduces oxygen concentration to decay the flame, cools down through physical and chemical heat absorption, and inhibits chemical chain reactions, forming a synergistic effect of multiple fire extinguishing mechanisms, which can effectively suppress combustion.

[0021] The present invention can also be configured with components such as dual steel containers and their valve bodies. Inert gas and FK chemical gas are stored separately in containers or combined into a single mixed container.

[0022] The ratio of helium to nitrogen in container one of this invention can also be set to 8:2. This invention also independently calculates the fire extinguishing concentrations for Class A and B fires, the fire extinguishing concentrations for ternary lithium batteries and lithium iron phosphate batteries, the calculation methods / formulas for the dosage of mixed gas extinguishing agents, the calculation methods for storage / driving pressure, and the design calculation methods for mixed applications. These calculations of concentration and dosage are original calculations based on the formula and ratio of this application. Attached Figure Description

[0023] Figure 1 This is a schematic diagram illustrating the calculation method of the constant 'a' in the van der Waals formula for calculating the container pressure of container one of the present invention.

[0024] Figure 2 This is a schematic diagram illustrating the calculation method of the constant b in the van der Waals formula of the container pressure calculation formula of container one of the present invention. Detailed Implementation

[0025] The present invention will now be further described with reference to the accompanying drawings.

[0026] See Figures 1-2 This invention provides a method for extinguishing fires using mixed gas in ternary lithium battery modules: The system includes two containers. Container 1 contains helium and nitrogen gas in a 6:4 ratio. Container 2 contains perfluorohexanone and nitrogen gas in a partially dissolved state in perfluorohexanone, which is used as a driving gas. The volume ratio of perfluorohexanone to nitrogen gas in container 2 is 77% and 23%, respectively. The system uses a combined fire suppression method, with container 1 activated first and container 2 activated later, mixing the gases in both containers within the ternary lithium battery module for fire suppression.

[0027] The actual values ​​of the extinguishing concentration of the gas in Container 1 and Container 2 were obtained based on theoretical research and testing experiments using a flame cup burner and a lithium battery combustion test chamber.

[0028] The design value for the extinguishing concentration of the gas in container one and container two is: actual extinguishing concentration + actual extinguishing concentration × 30%.

[0029] The actual extinguishing concentration of the gas in container one is 45%; the actual extinguishing concentration of the gas in container two is 20%.

[0030] The calculation formulas for the design values ​​of fire extinguishing or inertia dosage of helium and nitrogen gas I in container one and nitrogen gas II in container two are as follows: ; The constant of helium Here, T is the numerical value of the temperature variable; The constant of nitrogen Here, T is the numerical value of the temperature variable; ; Where Q is the design value of total flooding extinguishing or degradation dosage, in kg; K is the altitude correction factor for the protected area; H is the altitude, in meters; s is the vapor specific volume of helium or nitrogen at the lowest expected temperature in the protected area when the pressure is 101.325 kPa, in cubic meters per second. 3 / kg; T represents the minimum expected temperature of the protected area, in °C; C represents the design value of the extinguishing concentration or the design value of the chemical dosage for the protected area, in °C.

[0031] The formula for calculating the design value of the fire extinguishing or inactivation dosage of perfluorohexanone in container two is as follows: ; ; ; Where Q is the design value of total flooding extinguishing or degradation dosage, in kg. K is the altitude correction factor for the protected area; H is the altitude, in meters; s is the vapor specific volume of perfluorohexanone at the lowest expected temperature in the protected area at a pressure of 101.325 kPa, in cubic meters per second. 3 / kg; T represents the minimum expected temperature of the protected area, in °C; C represents the design value of the fire extinguishing concentration or the design value of the degradation concentration of the protected area, in °C.

[0032] The formula for calculating the container pressure of container one is: ; Where P is the container pressure (in L); V is the extinguishing agent volume; M is the extinguishing agent mass (in kg); n is the molar mass = V / 22.4; and T is the temperature. V represents the volume of the extinguishing agent, specifically: V1 = M / 0.1786 × 1000; V1 is the volume of helium gas; V2 = M / 1.25 × 1000; V2 is the volume of nitrogen gas 1; R is the ideal gas constant. When the units of P, V, n, and T are atm, L, mol, and K, respectively, the value of R is 8.314, and the unit is kPa. Where R is the ideal gas constant known to the international scientific community, and its value is: The gas constant is a constant that characterizes the thermodynamic properties of an ideal gas. It is the ratio of the product of the absolute pressure p and specific volume v of an ideal gas to its thermodynamic temperature T. It is usually represented by the symbol "R" and its unit is "J / (kg·K)". Helium and nitrogen are inert gases that are close to ideal gases, and this constant is generally used for them. However, carbon dioxide differs significantly from the ideal gas constant, so its actual gas properties must be used.

[0033] a is 0.33615, b is 0.02976; The gas mixture in container one differs from the other single gases; specifically, the van der Waals constants 'a' and 'b' in its pressure calculation formula (van der Waals Equation) are different from those for helium (a=0.0346, b=0.0237) and nitrogen (a=1.3900, b=0.0391). The values ​​of 'a' and 'b' in container one need to be calculated, and are obtained as follows: a=0.33615 bar·L² / mol², b=0.02976 L / mol.

[0034] The constants 'a' and 'b' in the van der Waals formula are characteristic parameters of the substance. These constants are not calculated using a single formula directly derived theoretically, but are usually obtained by fitting experimental data. However, they have definite physical meanings and can be determined through various experimental or theoretical methods. Since we already have known constants for helium and nitrogen, they can be obtained relatively easily through theoretical calculations. Helium: mole fraction Nitrogen: mole fraction It requires pure matter. (This can be found in the data table; it usually comes from critical parameters.)

[0035] Find the typical value of van der Waals constant (SI unit: for , for Helium: a = 0.00346; b = 2.38 × 10⁻⁶ -5 Nitrogen: a=0.137; b=3.87×10 -5 .

[0036] Then, calculations are performed using critical parameters combined with the van der Waals equation. (Gas mixture, van der Waals constant) and We cannot simply use a volume-weighted average; instead, we need to apply mixing rules. This is because the interactions between different molecules differ from those between molecules of the same kind, especially... The parameter (representing attractiveness) needs to be adjusted for cross terms.

[0037] In container one The mixed gas in the new technology differs from other single gases, specifically the van der Waals constants a and b in its pressure calculation formula (van der Waals Equation) are different from those of helium (a=0.0346, b=0.0237) and nitrogen (a=1.3900, b=0.0391).

[0038] Mixed gas in container one It was obtained through calculation: The constants a = 0.33615 bar·L² / mol² and b = 0.02976 L / mol. In the van der Waals formula, constants a and b are characteristic parameters of the substance. These constants are not calculated using a single formula directly derived theoretically, but are usually obtained by fitting experimental data. However, they have clear physical meanings and can be determined through various experimental or theoretical methods. Since we already have known constants for helium and nitrogen, they can be obtained relatively easily through theoretical calculations (see appendix). Figure 1 and attached Figure 2 ): Helium: mole fraction Nitrogen: mole fraction ; Requires pure substances (This can be found in the data table; it usually comes from critical parameters.)

[0039] Find the typical value of van der Waals constant (SI unit: for , for ): Helium: a = 0.00346; b = 2.38 × 10⁻⁶ -5 ; Nitrogen: a = 0.137; b = 3.87 × 10 -5 ; Then, calculations are performed using critical parameters combined with the van der Waals equation. (Gas mixture, van der Waals constant) and We cannot simply use a volume-weighted average; instead, we need to apply mixing rules. This is because the interactions between different molecules differ from those between molecules of the same kind, especially... The parameters (representing attractive force) require cross-term correction: bar·L² / mol², L / mol.

[0040] The pressure in container two is calculated based on the volumetric proportion of the driving gas from nitrogen two, specifically as follows: ; Where P is the container pressure (L); V is the extinguishing agent volume (L); and M is the extinguishing agent mass (kg). n is the molar mass = V / 22.4; T is the temperature; V represents the volume of the extinguishing agent, specifically: V 氮 ==M / 1.25×1000; R is the ideal gas constant. When the units of P, V, n, and T are atm, L, mol, and K, respectively, the value of R is 8.314, and the unit is kPa. The R here is the same as that of a container.

[0041] a is 1.3900 and b is 0.0391. The values ​​of a and b for container two here are only the van der Waals constants for nitrogen (a=1.3900, b=0.0391).

[0042] The working principle of this invention is as follows: The primary fuel in lithium battery fires is the electrolyte, a mixture of hydrocarbons and oxygen, which is a flammable liquid (Class B fuel) and a flammable gas produced through thermal decomposition (Class C fuel). However, the ignition and combustion of the electrolyte originate from thermal runaway due to lithium battery malfunction. This involves not only the heat of combustion of Class B and Class C fuels but also the electrical energy from the high state of charge (SOC) of the lithium battery. Its heat release rate is 200-300% higher than that of ordinary Class B and Class C fires. Therefore, the extinguishing agents and methods used in these fires differ significantly from conventional firefighting methods.

[0043] Known gaseous fire extinguishing technologies, such as inert gases like IG-100 and IG-541, and chemical gases like FK-5-1-12 and HFC-227ea, are ineffective at extinguishing ternary lithium battery fires due to their respective characteristics and limitations. Based on the mechanism of gaseous fire extinguishing technology, we employ a synergistic application of mixed ternary gases to overcome their individual shortcomings. This enhances the fire extinguishing mechanism of heat absorption and cooling combined with degradation and asphyxiation (reducing oxygen concentration), achieving rapid fire suppression and maintaining a long-term, difficult-to-reignite environment. This synergistic and complementary effect is reflected in the system design through the following invention points 2 and 3.

[0044] The ternary gas fire extinguishing system of this invention is a hybrid system that combines two basic technologies: namely, IG-64 in container one. The fire suppression technology combines the IG-64 technology with the FK technology of Container 2. IG-64 is a fire suppression technology using a mixture of He (helium) and N2 (nitrogen) inert gases; FK is the FK-5-1-12 fire suppression technology. The two technologies work together in a synergistic, two-stage time-difference release to achieve more effective fire suppression and prevention of reignition.

[0045] The choice of He as the main component is also based on: 1. He has a high constant-pressure specific heat capacity of 5191 J / kg, meaning its constant-pressure heat capacity is related to temperature. A higher constant-pressure heat capacity means that the same mass of gas absorbs the same amount of heat, resulting in a smaller temperature change and thus a stronger heat absorption and cooling capacity. As a monatomic gas, its constant-pressure heat capacity remains almost constant across the entire temperature range, stabilizing at around 5191 J / (kg / K). This is because the molecular motion of monatomic gases is primarily translational; temperature changes do not trigger other motion modes, so the heat capacity is essentially unaffected by temperature. Although He gas has a very low specific gravity, with a mass 7 times smaller than N2 gas of the same volume and a constant-pressure specific heat capacity 1.4 times smaller, He's thermal conductivity and specific heat capacity ratio (characteristics 2 and 3 below) give it better heat absorption efficiency. Therefore, the extinguishing concentration of He for Class B fires is 25% compared to N2's 42% for Class B fires.

[0046] 2. He has a high thermal conductivity, meaning its thermal conductivity is related to temperature. The higher the thermal conductivity, the faster the gas transfers heat, and the faster the cooling effect. He has the highest thermal conductivity at all temperatures, reaching 0.1557 at 300K. It has a thermal conductivity that is 6 times that of N2 and 9 times that of Ar (argon). This extremely high thermal conductivity stems from its extremely low molar mass and simple single-atom structure, which allows its molecules to move quickly and efficiently transfer and absorb heat.

[0047] 3. Based on He's specific heat ratio (Cp / Cv=1.66) and the characteristics of the cooling process, this means that the temperature change is more drastic during adiabatic processes. In practical cooling applications, this characteristic allows monatomic gases to generate a greater temperature drop during adiabatic expansion, making it suitable for rapid heat absorption and cooling in fire environments.

[0048] FK (FK-5-1-12) gas rapidly extinguishes fires by absorbing heat from flames through the high heat capacity of its chemical molecules. While it has excellent fire extinguishing performance, its fatal flaw is that when high-energy-density batteries such as ternary lithium batteries catch fire, the extremely high temperatures generated cause FK gas to thermally decompose at 600 degrees Celsius, converting into a large amount of non-extinguishing gases such as hydrogen fluoride. Although thermal decomposition absorbs some heat, it cannot absorb enough heat to suffocate the flames. At the same time, the designed fire extinguishing concentration of FK gas is insufficient to offset the oxygen concentration that supports combustion in the combustion space due to thermal decomposition, thus completely losing its fire extinguishing ability. The technology utilizes inert gases, comprising 60% He (helium) and 40% N2 (nitrogen). Besides He's high specific heat capacity of 5.193 kJ / (kg·℃) and N2's specific heat capacity of 1.040 kJ / (kg·℃), which can absorb a large amount of flame heat, both He and N2 are inert gases. Their dosage can be designed to effectively reduce the oxygen concentration in the combustion zone, suffocating the flame. Even if the high temperature and flame cannot be completely suppressed, the flame is significantly inhibited and weakened in a low-oxygen environment. Then, FK is sprayed into the flame area immediately afterward or at intervals of several seconds. Working synergistically with IG-64 in container one, it not only avoids thermal decomposition but also effectively further suppresses the weakened flame due to low oxygen concentration. More importantly, the FK in container two can suppress reignition for a long time. Even if the electrolyte of the ternary lithium battery is still in a decomposed state and continues to release and replenish oxygen to the combustion zone, it may reignite the flammable gas released by the electrolyte in the zone. The FK gas, which fills the zone and is mixed with flammable gas, has a high specific heat capacity and can effectively work with He, which has a high specific heat capacity, high thermal conductivity and high specific heat ratio, to effectively absorb the heat of the reignited flame, suppress its reignition or prevent the flame from surviving in the FK-He mixture.

[0049] The fire extinguishing method adopts a staged activation approach: first, container one is activated, utilizing the heat absorption capacity of the novel inert gas within it to quickly reduce the internal temperature of the battery module to below 500°C; once the temperature drops below 500°C, container two is activated to release perfluorohexanone fire extinguishing agent; perfluorohexanone does not undergo thermal decomposition at 500°C, and achieves cell fire control and reignition suppression through the mechanisms of absorbing flame energy and converting it into intramolecular energy, asphyxiation, capturing free radicals, and blocking the flame chain reaction; The inert gas in container one and the gas in container two mix with each other within the ternary lithium battery module, forming a composite, complementary, and synergistic effect, thereby achieving efficient fire extinguishing.

[0050] The dosage of the three gases in this invention is calculated based on the fire extinguishing concentration design of the space volume or the volume of the lithium battery box / cabinet. The fire extinguishing concentration is determined through theoretical research and combustion experiments (including tests using flame cup burners and lithium battery combustion test chambers). The fire extinguishing concentration and design concentration are determined (international convention: the design concentration is 30% higher than the fire extinguishing concentration). The design concentration varies for different types of batteries, specifically: Ternary lithium batteries: The extinguishing concentration of IG-64 is 45% + the design concentration, which is 58.5% for fire suppression. FK extinguishing concentration 20% + design addition concentration, i.e., extinguishing design concentration 26%; Lithium iron phosphate batteries with a capacity of 200Ah or higher: The extinguishing concentration of IG-64 is 37% + the design concentration, which is 48% for fire suppression. The FK extinguishing concentration is 12% + the design addition concentration, which is equivalent to a extinguishing design concentration of 15.6%. Fire extinguishing concentration for lithium iron phosphate batteries below 200Ah: The extinguishing concentration of IG-64 is 35% + the design concentration, which is 45.5% for fire suppression. FK extinguishing concentration 9% + design addition concentration, i.e., extinguishing design concentration 12%; For uncharged batteries (SOC=0%), the fire hazard is equivalent to a Class B (solid fuel) fire. The extinguishing concentration of IG-64 is 35% + the design concentration, which is 45.5% for fire suppression. The FK extinguishing concentration is 4.5% + the design addition concentration, which is the extinguishing design concentration of 5.9%.

[0051] The above are merely preferred embodiments of the present invention, intended only to aid in understanding the method and core ideas of this application. The scope of protection of the present invention is not limited to the above embodiments; all technical solutions falling within the scope of the present invention's concept are within its protection. It should be noted that for those skilled in the art, any improvements and modifications made without departing from the principles of the present invention should also be considered within the scope of protection of the present invention.

[0052] This invention comprehensively solves the problem of uncontrollable fires in passenger vehicle power batteries (ternary lithium batteries) in existing technologies. It involves first injecting He and N2 from a ternary mixed gas into the battery box to synergistically reduce oxygen concentration, weaken or suffocate the flames, and simultaneously cool the battery and initially suppress the fire. Then, FK is sprayed into the power battery box to further suppress the fire and prevent reignition, thus effectively suppressing power battery fires. The ternary mixed gas of this invention not only efficiently suppresses and extinguishes lithium battery combustion but also effectively suppresses the explosion of lithium battery module boxes. Furthermore, the ternary mixed gas is a clean gas, and its spraying will not cause environmental pollution due to the inhibitor itself. Because the ternary mixed gas of this invention uses a relatively low mass, it has minimal impact on the load and mileage of passenger vehicles. The high specific heat and low density of He in the mixture mean that a small mass of He is sufficient for the suppression effect. Additionally, the high extinguishing efficiency of FK means that the required amount is also low under the condition of significant He cooling.

[0053] Most importantly, none of the existing single fire extinguishing gases can extinguish fires involving extremely high-temperature, high-energy-density ternary lithium batteries, and water-based fire extinguishing agents are not suitable for the limited space of a car. However, the small-volume ternary gas fire extinguishing system has successfully overcome the difficulty of extinguishing fires in ternary lithium battery module boxes, providing excellent fire safety protection for new energy vehicles.

Claims

1. A method for extinguishing fires involving mixed gases in ternary lithium battery modules, characterized in that, The system includes two containers: container one and container two. Container one contains helium and nitrogen gas in a 6:4 ratio. Container two contains perfluorohexanone and nitrogen gas, which is used as a driving gas and is partially dissolved in the perfluorohexanone. The volume ratio of perfluorohexanone to nitrogen gas in container two is 77% and 23%, respectively. Container one is activated first, followed by container two, to mix the gases in the two containers within a ternary lithium battery module for fire suppression.

2. The method for extinguishing fires using a mixed gas in a ternary lithium battery module according to claim 1, characterized in that, The actual values ​​of the extinguishing concentration of the gas in container one and container two were obtained based on theoretical research and testing experiments using a flame cup burner and a lithium battery combustion test chamber.

3. The method for extinguishing fires using a mixed gas in a ternary lithium battery module according to claim 2, characterized in that, The design value for the extinguishing concentration of the gas in container one and container two is: actual extinguishing concentration + actual extinguishing concentration × 30%.

4. The method for extinguishing fires using mixed gas in ternary lithium battery modules according to claim 3, characterized in that, The actual fire extinguishing concentration of the gas in container one is 45%; the actual fire extinguishing concentration of the gas in container two is 20%.

5. The method for extinguishing fires using a mixed gas in a ternary lithium battery module according to claim 1, characterized in that, The calculation formulas for the design values ​​of fire extinguishing or degradation dosages of helium in container one, nitrogen one, and nitrogen two in container two are all as follows: ; The constant of helium Here, T is the numerical value of the temperature variable; The constant of nitrogen Here, T is the numerical value of the temperature variable; ; Where Q is the design value of total flooding extinguishing or degradation dosage, in kg; K is the altitude correction factor for the protected area; H is the altitude, in meters; s is the vapor specific volume of helium or nitrogen at the lowest expected temperature in the protected area when the pressure is 101.325 kPa, in cubic meters per second. 3 / kg; T represents the minimum expected temperature of the protected area, in °C; C represents the design value of the extinguishing concentration or the design value of the chemical dosage for the protected area, in °C.

6. The method for extinguishing fires using a mixed gas in a ternary lithium battery module according to claim 1, characterized in that, The calculation formula for the design value of the fire extinguishing dosage or the design value of the inactivation dosage of perfluorohexanone in container two is as follows: ; ; ; Where Q is the design value of total flooding extinguishing or degradation dosage, in kg. K is the altitude correction factor for the protected area; H is the altitude, in meters; s is the vapor specific volume of perfluorohexanone at the lowest expected temperature in the protected area at a pressure of 101.325 kPa, in cubic meters per second. 3 / kg; T represents the minimum expected temperature of the protected area, in °C; C represents the design value of the fire extinguishing concentration or the design value of the degradation concentration of the protected area, in °C.

7. The method for extinguishing fires using a mixed gas for extinguishing ternary lithium battery modules according to claim 1, characterized in that, The formula for calculating the container pressure of container one is as follows: ; Where P is the container pressure (in L); V is the extinguishing agent volume; M is the extinguishing agent mass (in kg); n is the molar mass = V / 22.4; and T is the temperature. V represents the volume of the extinguishing agent, specifically: V1 = M / 0.1786 × 1000; V1 is the volume of helium gas; V2 = M / 1.25 × 1000; V2 is the volume of nitrogen gas 1; R is the ideal gas constant. When the units of P, V, n, and T are atm, L, mol, and K, respectively, the value of R is 8.314, and the unit is kPa. a is 0.33615, and b is 0.02976.

8. The method for extinguishing fires using a mixed gas in a ternary lithium battery module according to claim 1, characterized in that, The container pressure of container two is calculated based on the proportion of the driving gas volume of nitrogen two, specifically as follows: ; Where P is the container pressure (L); V is the extinguishing agent volume (L); and M is the extinguishing agent mass (kg). n is the molar mass = V / 22.4; T is the temperature; V represents the volume of the extinguishing agent, specifically: In 氮 ==M / 1.25×1000; R is the ideal gas constant. When the units of P, V, n, and T are atm, L, mol, and K, respectively, the value of R is 8.314, and the unit is kPa. a is 1.3900, and b is 0.0391.

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