High-efficiency fire extinguishing agent suitable for lithium ion battery and preparation method thereof

Abstract

The application relates to the field of fire fighting, and discloses a high-efficiency fire extinguishing agent suitable for lithium ion batteries and a preparation method thereof, which is composed of the following components in percentage by mass: ethylene glycol 42-48%, di-potassium hydrogen phosphate 5-9%, sodium secondary alkyl sulfonate 0.8-1.2%, sodium alpha-alkenyl sulfonate 0.8-1.2%, and the balance is deionized water. In the application, the effects of interrupting the thermal runaway chain reaction, cutting off the oxygen supply and fuel source of combustion, and simultaneously reducing the battery core temperature to below the safety threshold are achieved, and the problems that in the traditional fire extinguishing agent, the dry powder only extinguishes surface fire, it is difficult to suppress internal thermal runaway, the rekindling rate is more than 85%, and the residues easily corrode the battery are solved.

Description

Technical Field

[0001] This invention relates to the field of fire protection, and in particular to a highly efficient fire extinguishing agent suitable for lithium-ion batteries and its preparation method. Background Technology

[0002] In recent years, with the rapid development of the global new energy industry, lithium-ion batteries have been widely used in energy storage systems, new energy vehicles, and consumer electronics due to their advantages such as high energy density and long cycle life. According to statistics from the International Energy Agency (IEA), the global installed capacity of lithium-ion batteries exceeded 1,000 GWh in 2023, a year-on-year increase of 35%. However, at the same time, fire accidents caused by lithium-ion batteries have also shown an upward trend year by year. In 2023, there were 42 publicly reported fire incidents at energy storage power stations and more than 12,000 fire incidents involving new energy vehicles worldwide, causing huge losses to personal safety and property.

[0003] In existing technologies, thermal runaway in lithium-ion batteries is a complex chain reaction. When the temperature reaches a critical value, the positive electrode decomposes and releases oxygen and heat, while the negative electrode reacts with the electrolyte to generate flammable gas, which in turn causes combustion, shell rupture, and even large-scale fires.

[0004] Traditional fire extinguishing agents have significant limitations: dry powder only extinguishes surface fires, struggles to suppress internal thermal runaway, has a reignition rate exceeding 85%, and its residues can easily corrode batteries. Ordinary water-based fire extinguishing agents have poor penetration and low cooling efficiency, while fluorinated water-based agents, although highly efficient, are polluting. Therefore, this paper proposes a highly efficient fire extinguishing agent suitable for lithium-ion batteries and its preparation method. Summary of the Invention

[0005] To achieve the above objectives, the present invention provides the following technical solution: A highly efficient fire extinguishing agent suitable for lithium-ion batteries comprises, by weight percentage: 42%-48% ethylene glycol, 5%-9% dipotassium hydrogen phosphate, 0.8%-1.2% sodium secondary alkyl sulfonate, 0.8%-1.2% sodium α-olefin sulfonate, with the balance being deionized water.

[0006] As a further description of the above technical solution: The ethylene glycol has a mass percentage of 45%, dipotassium hydrogen phosphate has a mass percentage of 7%, sodium secondary alkyl sulfonate and sodium α-olefin sulfonate each have a mass percentage of 1%, and deionized water has a mass percentage of 46%.

[0007] As a further description of the above technical solution: The resistivity of the deionized water is ≥18 MΩ・cm.

[0008] As a further description of the above technical solution: The ethylene glycol is industrial grade with a purity ≥99.5%; the dipotassium hydrogen phosphate is food additive grade with a purity ≥99.0%; and the sodium secondary alkyl sulfonate and sodium α-olefin sulfonate are industrial grade with an active ingredient content ≥90%.

[0009] As a further description of the above technical solution: A method for preparing the fire extinguishing agent according to any one of claims 1-4, comprising the following steps: S1: Weigh each component according to its mass percentage; S2: Pour deionized water into the stirred tank, turn on low-speed stirring, slowly add dipotassium hydrogen phosphate, and stir until completely dissolved; S3: Add ethylene glycol, adjust the stirring speed, and control the stirring time; S4: Add sodium secondary alkyl sulfonate and sodium α-olefin sulfonate sequentially, maintaining the rotation speed; S5: After filtration, store in a sealed container at room temperature away from light.

[0010] The present invention has the following beneficial effects: 1. In this invention, through the synergistic effect of chemical inhibition, suffocation isolation and rapid cooling, the thermal runaway chain reaction is interrupted, the oxygen supply and fuel source for combustion are cut off, and the core temperature of the battery is reduced to below the safety threshold. This solves the problem that dry powder in traditional fire extinguishing agents only extinguishes surface fires, is difficult to suppress internal thermal runaway, has a reignition rate of over 85%, and the residue is easy to corrode the battery.

[0011] 2. In this invention, all components are non-toxic and non-corrosive substances. The residue after extinguishing the fire is a mixture of dipotassium hydrogen phosphate and ethylene glycol, which can be completely removed by rinsing with water. It will not corrode battery equipment or pollute the environment. The agent has no irritating odor and is harmless to the human body. It achieves low pollution and high safety, solving the problem that existing fluorinated water-based agents, although highly efficient, are polluting. Attached Figure Description

[0012] Figure 1 This is a schematic diagram of the parameters of the present invention. Detailed Implementation

[0013] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0014] In one embodiment, 100 kg of fire extinguishing agent for lithium-ion batteries is prepared, with the following amounts of each component: 45 kg of ethylene glycol, 7 kg of dipotassium hydrogen phosphate, 1 kg of sodium secondary alkyl sulfonate, 1 kg of sodium α-olefin sulfonate, and 46 kg of deionized water.

[0015] The preparation steps for 100kg of lithium-ion battery-specific fire extinguishing agent are as follows: Step 1: Add 46kg of deionized water to a 200L stainless steel stirring vessel, turn on the stirring speed of 120r / min, slowly add 7kg of dipotassium hydrogen phosphate, and stir for 12min until completely dissolved. Step 2: Add 45 kg of ethylene glycol, adjust the stirring speed to 220 r / min, and stir for 13 min; Step 3: Add 1 kg of secondary alkyl sulfonate and 1 kg of α-olefin sulfonate in sequence, and stir at 220 r / min for 23 min. Step 4: After filtering with a 200-mesh stainless steel filter, put the medicine into a sealed plastic bucket and store it at room temperature away from light.

[0016] In the above embodiments, ethylene glycol has a specific heat capacity of 2.43 J / g·℃ and a boiling point of 197.3℃, which is much higher than that of water. This allows it to continuously absorb heat in high-temperature environments, achieving long-term cooling of the battery surface and interior. Its heat of vaporization at 100℃ is 812 kJ / kg, 1.4 times that of water, enabling it to rapidly remove a large amount of heat during evaporation. Furthermore, as a polar solvent, ethylene glycol is completely miscible with deionized water and significantly improves the solubility of dipotassium hydrogen phosphate. When the temperature reaches 25℃, the solubility of dipotassium hydrogen phosphate in an ethylene glycol aqueous solution is 32% higher than in pure water, promoting uniform dispersion of solid components and preventing stratification or precipitation during storage. In addition, a 42%-48% ethylene glycol aqueous solution has a freezing point as low as -22℃ to -28℃, allowing for normal use in cold regions without the need for additional antifreeze. Dipotassium hydrogen phosphate is the core component of this invention for achieving multi-dimensional fire suppression, inhibiting thermal runaway through a four-fold action: 1. Chemical inhibition: Dipotassium hydrogen phosphate begins to decompose when heated to 180°C, generating intermediate products such as potassium dihydrogen phosphate and potassium pyrophosphate. When the temperature rises above 500°C, the core temperature of thermal runaway in lithium-ion batteries, it further decomposes to produce active groups such as PO4^3- and HPO4^2-. These groups can react with chain reaction intermediates such as ·OH and ·O to generate stable substances such as H3PO4 and H2O, effectively interrupting the thermal runaway chain reaction. According to tests, the dipotassium hydrogen phosphate in the agent of this invention can capture more than 90% of thermal runaway free radicals, reducing the thermal runaway propagation rate by 85%.

[0017] 2. Suffocation isolation effect: During the decomposition of dipotassium hydrogen phosphate, a large amount of water vapor is released. 1 mol of dipotassium hydrogen phosphate can produce 0.5 mol of water vapor, which can quickly dilute the oxygen concentration around the fire to below 12%, of which the critical oxygen concentration for combustion is 16%. At the same time, the molten phosphate produced by decomposition, which has a melting point of about 800℃, will form a dense glassy isolation layer on the battery shell and electrode surface, with a thickness of 0.2-0.5 mm. This not only prevents external oxygen from penetrating into the battery, but also inhibits the escape of combustible gases from inside the battery, cutting off the oxygen supply and fuel source for combustion.

[0018] 3. Enhanced cooling effect: The decomposition reaction of dipotassium hydrogen phosphate is a strongly endothermic reaction. Every 100g of dipotassium hydrogen phosphate can absorb about 125kJ of heat during decomposition, directly reducing the temperature of the fire scene. Combined with the evaporative heat cooling of ethylene glycol, the surface temperature of the battery can be reduced from 800℃ to below 200℃ within 30s, and the core temperature of the battery can be stably controlled below 60℃ within 120min, completely eliminating the risk of thermal runaway and reignition. The combined use of two surfactants can achieve synergistic effects: sodium secondary alkyl sulfonate has excellent penetration properties (HLB value 13-15), which can rapidly reduce the surface tension of the agent to 28-32 mN / m, allowing the agent to penetrate into the porous structure of the battery electrode with a pore size of only 10-50 μm; sodium α-olefin sulfonate has good emulsifying and dispersing properties (HLB value 12-14), which can uniformly disperse dipotassium hydrogen phosphate in aqueous solution, avoiding precipitation caused by excessively high local concentrations. Furthermore, the composite surfactant can significantly improve the agent's resistance to hard water. In hard water with a hardness of 500 mg / L, the agent does not produce any precipitation after standing for 72 hours, and its fire extinguishing performance remains above 95%. Furthermore, the surfactant is biodegradable, with a BOD5 / COD value ≥ 0.6, and it has no bioaccumulation, meeting environmental protection requirements.

[0019] Deionized water has a resistivity ≥18 MΩ·cm, which can prevent metal ions in the water from causing battery short circuits and eliminate electrical safety hazards. Its evaporation endothermic temperature is 2260 kJ / kg, which can assist ethylene glycol and dipotassium hydrogen phosphate in achieving rapid cooling. At the same time, deionized water, as a solvent, can dissolve various functional components, ensuring the fluidity and sprayability of the agent, making it suitable for various fire spraying equipment. Example 1: Preparation of 100 kg of fire extinguishing agent specifically for lithium-ion batteries. The amounts of each component are as follows: ethylene glycol 45 kg, dipotassium hydrogen phosphate 7 kg, sodium secondary alkyl sulfonate 1 kg, sodium α-olefin sulfonate 1 kg, and deionized water 46 kg. Preparation steps:

[0020] S1: Add 46kg of deionized water to a 200L stainless steel stirring vessel, turn on the stirring speed of 120r / min, slowly add 7kg of dipotassium hydrogen phosphate, and stir for 12min until completely dissolved. S2: Add 45 kg of ethylene glycol, adjust the stirring speed to 220 r / min, and stir for 13 min; S3: Add 1 kg of secondary alkyl sulfonate and 1 kg of α-olefin sulfonate sequentially, and stir at 220 r / min for 23 min. S4: After filtering with a 200-mesh stainless steel filter, put the medicine into a sealed plastic bucket and store it at room temperature away from light. Example 2: 100 kg of fire extinguishing agent was prepared with the following components in the following amounts: ethylene glycol 42 kg, dipotassium hydrogen phosphate 9 kg, sodium secondary alkyl sulfonate 1 kg, sodium α-olefin sulfonate 1 kg, and deionized water 47 kg. The preparation steps were the same as in Example 1. This formulation is suitable for fire suppression in large-scale energy storage power stations, and has a stronger chemical inhibition effect. Example 3: 100 kg of fire extinguishing agent was prepared with the following components in the following amounts: 48 kg ethylene glycol, 5 kg dipotassium hydrogen phosphate, 1 kg sodium secondary alkyl sulfonate, 1 kg sodium α-alkenyl sulfonate, and 45 kg deionized water. The preparation steps were the same as in Example 1. This formulation is suitable for cold regions, exhibiting better low-temperature fluidity and cooling effect.

[0021] Comparative Example 1: Formulation composition: 45% ethylene glycol, 7% dipotassium hydrogen phosphate, 2% sodium secondary alkyl sulfonate, with the remainder being deionized water. The purity of each raw material is consistent with that of the present invention: industrial grade ethylene glycol ≥99.5%, food additive grade dipotassium hydrogen phosphate ≥99.0%, and industrial grade sodium secondary alkyl sulfonate active ingredient ≥90%. Preparation method: completely consistent with Example 1 of this invention, namely, dissolving dipotassium hydrogen phosphate at low speed, mixing ethylene glycol at high speed, adding surfactant and stirring, filtering with a 200-mesh filter and storing at room temperature away from light.

[0022] In summary, using a 100Ah square lithium iron phosphate battery as the test object, and employing a heating method to trigger thermal runaway, the test results are as follows: The fire extinguishing time was 45 seconds. After 120 minutes, the core temperature of the battery was 78°C. Reignition occurred 40 minutes after extinguishing. The surface tension of the agent was 35 mN / m, which could not effectively penetrate into the porous structure of the battery electrode and could only act on the surface of the battery. After standing for 72 hours, slight stratification occurred, and dipotassium hydrogen phosphate showed slight local crystallization and poor dispersibility.

[0023] Comparative Example 2: Formulation composition: 45% ethylene glycol, 1% sodium secondary alkyl sulfonate, 1% sodium α-olefin sulfonate, with the balance being deionized water. The resistivity is ≥18 MΩ·cm, and the purity of each raw material is consistent with that of the present invention. Preparation method: completely consistent with Example 1 of the present invention, except that the step of adding and dissolving dipotassium hydrogen phosphate is omitted.

[0024] Performance test results: Using a 100Ah square lithium iron phosphate battery as the test object, thermal runaway was triggered by needle penetration.

[0025] In summary: the agent can only extinguish surface flames, with an extinguishing time of 60 seconds. It cannot interrupt the thermal runaway chain reaction inside the battery. Violent reignition occurs 10 minutes after extinguishing, and the core battery temperature still reaches 92°C after 120 minutes. Without the chemical inhibition and suffocation isolation effect of potassium dihydrogen phosphate, relying solely on the cooling effect of ethylene glycol and water cannot meet the core requirements for extinguishing lithium-ion battery fires. The agent does not form an isolation layer at high temperatures, and combustible gases continue to escape from inside the battery, making it impossible to stop the combustion at its source.

[0026] The above embodiments are merely illustrative of the technical solutions of the present invention and are not intended to limit it. Anyone skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A highly efficient fire extinguishing agent suitable for lithium-ion batteries, characterized in that, include: It consists of the following components by mass percentage: 42%-48% ethylene glycol, 5%-9% dipotassium hydrogen phosphate, 0.8%-1.2% sodium secondary alkyl sulfonate, 0.8%-1.2% sodium α-alkenyl sulfonate, and the balance being deionized water.

2. The high-efficiency fire extinguishing agent suitable for lithium-ion batteries according to claim 1, characterized in that: The ethylene glycol has a mass percentage of 45%, dipotassium hydrogen phosphate has a mass percentage of 7%, sodium secondary alkyl sulfonate and sodium α-olefin sulfonate each have a mass percentage of 1%, and deionized water has a mass percentage of 46%.

3. The high-efficiency fire extinguishing agent suitable for lithium-ion batteries according to claim 1, characterized in that: The resistivity of the deionized water is ≥18 MΩ・cm.

4. The high-efficiency fire extinguishing agent suitable for lithium-ion batteries according to claim 3, characterized in that: The ethylene glycol is industrial grade with a purity ≥99.5%; the dipotassium hydrogen phosphate is food additive grade with a purity ≥99.0%; the sodium secondary alkyl sulfonate and sodium α-olefin sulfonate are industrial grade with an active ingredient content ≥90%.

5. A method for preparing the fire extinguishing agent according to any one of claims 1-4, characterized in that, Includes the following steps: S1: Weigh each component according to its mass percentage; S2: Pour deionized water into the stirred tank, turn on low-speed stirring, slowly add dipotassium hydrogen phosphate, and stir until completely dissolved; S3: Add ethylene glycol, adjust the stirring speed, and control the stirring time; S4: Add sodium secondary alkyl sulfonate and sodium α-olefin sulfonate sequentially, maintaining the rotation speed; S5: After filtration, store in a sealed container at room temperature away from light.

6. The high-efficiency fire extinguishing agent suitable for lithium-ion batteries and its preparation method according to claim 4, characterized in that, S3 also includes the following steps: S31: After ethylene glycol is mixed with deionized water, the density deviation of the reagent is ≤0.5%.

7. The high-efficiency fire extinguishing agent suitable for lithium-ion batteries and its preparation method according to claim 4, characterized in that, S4 also includes the following steps: The micelles formed by the complete dispersion of sodium secondary alkyl sulfonate and sodium α-olefin sulfonate have a particle size ≤100nm.

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