A fire extinguishing agent for heat-sensitive lithium batteries and its preparation method

Abstract

The present invention relates to the technical field of fire extinguishing agents, and discloses a special fire extinguishing agent for heat-sensitive lithium batteries and a preparation method thereof. The raw material components, measured by weight, include 1-5 parts of a surfactant, 10-25 parts of an aprotic solvent, 2-5 parts of a fire extinguishing agent, 2-5 parts of a microcapsule agent, 3-10 parts of a temperature reducer, 2-10 parts of a heat-sensitive expansion agent, 1-8 parts of a heat-sensitive thickener, and 70-100 parts of deionized water. The special fire extinguishing agent provided by the present invention is prepared by adding a heat-sensitive expansion agent, a heat-sensitive thickener, and a microcapsule agent to a water-based fire extinguishing agent. When exposed to high flame temperatures, the fire extinguishing agent undergoes thermal expansion and increases in viscosity, thereby enhancing the adhesion of the water-based fire extinguishing agent to the surface of the lithium battery.

Description

Technical Field

[0001] The present invention relates to the technical field of fire extinguishing agents, in particular to a fire extinguishing agent special for heat-sensitive lithium batteries and a preparation method thereof. Background Art

[0002] In terms of the application of fire extinguishing agents, when a lithium battery fire occurs, its internal core temperature rises sharply due to thermal runaway, and the flames quickly penetrate the surface of the battery to form a deflagration. Extinguishing the fire requires not only extinguishing the open flame, but also continuously cooling the battery until it stops heating and does not re-ignite. Currently, especially in open spaces, the use of various gas fire extinguishing agents, dry powder fire extinguishing agents, aerosol fire extinguishing agents, etc. to extinguish lithium battery fires has not been able to effectively solve the problem of battery re-ignition. While using water and ordinary water-based fire extinguishing agents to extinguish lithium battery fires can effectively extinguish the fire, they are easily lost during the fire extinguishing process, and a large amount of water and fire extinguishing agents are still required to suppress the re-ignition of thermal runaway lithium batteries. Summary of the Invention

[0003] Technical problems solved by the present invention:

[0004] The invention is used to solve the problem of poor fire extinguishing effect of water-based fire extinguishing agents in the prior art.

[0005] In response to the above technical problems, the present invention aims to provide a fire extinguishing agent specifically for heat-sensitive lithium batteries and a preparation method thereof. Specifically, the technical solution adopted by the present invention is as follows:

[0006] First, the present invention provides a special fire extinguishing agent for heat-sensitive lithium batteries. The raw material components, calculated by weight, include 1-5 parts of surfactant, 10-25 parts of aprotic solvent, 2-5 parts of fire extinguishing agent, 2-5 parts of microcapsule agent, 3-10 parts of cooling agent, 2-10 parts of heat-sensitive expansion agent, 1-8 parts of heat-sensitive thickener, and 70-100 parts of deionized water.

[0007] According to some preferred embodiments, the aforementioned raw material components preferably include 2-5 parts of surfactant, 10-15 parts of aprotic solvent, 2-5 parts of fire extinguishing agent, 2-5 parts of microcapsule agent, 3-6 parts of cooling agent, 2-5 parts of thermosensitive expansion agent, 1-3 parts of thermosensitive thickener, and 70-80 parts of deionized water.

[0008] According to some preferred embodiments, the surfactant includes at least one of a hydrocarbon surfactant and a fluorosurfactant; among the aforementioned, the hydrocarbon surfactant includes at least one of sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, and α-olefin sulfonate; the fluorosurfactant includes at least one of perfluorooctane sulfonate, perfluorohexane sulfonate, perfluorooctanoic acid, and perfluorohexanoic acid.

[0009] According to some preferred embodiments, the aprotic solvent includes a dimethylamine compound, specifically at least one of dimethylacetamide, N,N-dimethylformamide, and hexamethylphosphoramide.

[0010] According to some preferred embodiments, the fire extinguishing agent includes an α-hydroxypropionate organic compound, specifically including at least one of potassium dihydroxypropionate, sodium lactate, and calcium propionate.

[0011] According to some preferred embodiments, the microcapsule drug is made of perfluorohexanone as the core material, ethyl cellulose as the inner shell material, and SiO2 as the outer shell material. The specific preparation method is:

[0012] After dispersing perfluorohexanone in a perfluorocyclic ether solvent, an emulsifier (Tween-80, 0.5-2 wt% emulsifier) ​​was added and blended at high speed (12,000 rpm for 5 minutes) to obtain an emulsion. Ethyl cellulose, azobisisobutyronitrile (1-3 wt% of the ethyl cellulose), methacrylic acid, and methyl stearate were added to the emulsion under a nitrogen atmosphere. The reaction system was heated to 60-80°C for 2 hours. After the reaction, aqueous ammonia was added to adjust the pH to 10. TEOS was then added and stirred for 0.5-2 hours. The microcapsules were filtered, washed (alternately with ethanol and water), and dried. The mass ratio of perfluorohexanone, ethyl cellulose, methacrylic acid, methyl stearate, and TEOS was 50:1:0.2-0.8:0.2-0.5:0.8-1.2.

[0013] According to some preferred embodiments, the temperature reducing agent includes a trihydroxy salt organic compound, specifically at least one of triisopropanolamine, triethylamine, and triethanolamine.

[0014] According to some preferred embodiments, the heat-sensitive expansion agent includes aluminosilicate inorganic compound, specifically including at least one of zeolite, kaolinite, montmorillonite, illite, feldspar, and mica.

[0015] According to some preferred embodiments, the heat-sensitive thickener includes a non-ionic cellulose ether organic compound, specifically including at least one of hydroxypropyl methylcellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, and sodium carboxymethyl cellulose.

[0016] According to some preferred embodiments, the deionized water is ultrapure water or distilled water.

[0017] Second, the present invention provides a method for preparing the aforementioned heat-sensitive lithium battery fire extinguishing agent, comprising the following steps:

[0018] (1) Add surfactant, fire extinguishing agent, and cooling agent to the aprotic solvent and fully dissolve them;

[0019] (2) Add the solution obtained in (1) to deionized water and stir evenly;

[0020] (3) Heat the solution obtained in (2) to 35-50°C, add a thermosensitive thickener and stir evenly;

[0021] (4) Cool the solution obtained in (3) to room temperature, add the thermosensitive expansion agent and microcapsule agent and stir evenly;

[0022] (5) The solution obtained in (4) is allowed to stand for defoaming to obtain a fire extinguishing agent.

[0023] The technical mechanism and beneficial effects adopted by the present invention are:

[0024] The special fire extinguishing agent provided by the present invention incorporates a heat-sensitive expansion agent, a heat-sensitive thickener, and a microcapsule agent into a water-based fire extinguishing agent. When exposed to high flame temperatures, the fire extinguishing agent undergoes thermal expansion and increases in viscosity, thereby enhancing the adhesion of the water-based fire extinguishing agent to the surface of lithium batteries. Perfluorohexanone is coated to reduce its release before it takes effect, and the double-shell coating structure further enhances the coating effect while overcoming the stability issues of ethyl cellulose alone. Furthermore, cellulose is grafted and modified with methacrylic acid and methyl stearate to further enhance its weather resistance. DETAILED DESCRIPTION

[0025] To make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention are described clearly and completely below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer are used. Where the manufacturer of the reagents or instruments is not specified, all are conventional products that can be purchased commercially.

[0026] Example 1

[0027] This embodiment provides a method for preparing a fire extinguishing agent specifically for heat-sensitive lithium batteries, comprising the following steps:

[0028] Weigh 2 parts of sodium lauryl sulfate, 10 parts of dimethylacetamide, 2 parts of potassium dihydroxypropionate, 3 parts of microcapsule agent, 4 parts of triisopropanolamine, 1 part of kaolinite, 1 part of montmorillonite, 2 parts of sodium carboxymethyl cellulose, and 75 parts of deionized water in proportion.

[0029] The microcapsule preparation method involves dispersing perfluorohexanone in perfluorocyclic ether, adding an emulsifier (Tween-80, 1 wt% emulsifier), and blending with high-speed stirring (12,000 rpm for 5 minutes) to obtain an emulsion. The volume ratio of emulsion to perfluorohexanone is 1:4. Under a nitrogen atmosphere, ethyl cellulose, azobisisobutyronitrile (2 wt% of the ethyl cellulose), methacrylic acid, and methyl stearate are added to the emulsion. The reaction system is heated to 70°C for 2 hours. After the reaction is completed, aqueous ammonia is added to adjust the pH to 10. TEOS is then added and stirred for 1 hour. The mixture is filtered, washed alternately with ethanol and water, and dried to obtain the microcapsule preparation. The mass ratio of perfluorohexanone, ethyl cellulose, methacrylic acid, methyl stearate, and TEOS is 50:1:0.5:0.3:1.

[0030] (1) Add sodium lauryl sulfate, potassium dihydroxypropionate, microcapsule agent, and triisopropanolamine to dimethylacetamide and fully dissolve;

[0031] (2) Add the solution obtained in (1) to deionized water and stir evenly;

[0032] (3) Heat the solution obtained in (2) to 50°C, add sodium carboxymethyl cellulose and stir evenly;

[0033] (4) The solution obtained in (3) was allowed to stand for 12 h, then cooled to room temperature, and kaolinite and montmorillonite were added and stirred evenly;

[0034] (5) The solution obtained in (4) was allowed to stand for 24 hours to defoam and obtain a fire extinguishing agent.

[0035] Comparative Example 1

[0036] The difference between this comparative example and Example 1 is that sodium carboxymethyl cellulose was not added.

[0037] Comparative Example 2

[0038] The difference between this comparative example and Example 1 is that kaolin and montmorillonite are not added.

[0039] Comparative Example 3

[0040] The difference between this comparative example and Example 1 is that methacrylic acid and methyl stearate were not added.

[0041] Test example

[0042] The fire extinguishing performance of Example 1 and Comparative Examples 1-3 was tested using 150Ah lithium iron phosphate soft-pack batteries (size: 8mm*118mm*155mm) with a 100% SOC. The test was conducted in an explosion-proof box. A 200W heating rod was used to induce thermal runaway in the battery. The heating rod was turned off after thermal runaway. A water mist fire extinguishing system was installed above the explosion-proof box. The test results are shown in Table 1. max : Maximum temperature of battery surface, V 降 : average cooling rate when the maximum temperature of the battery surface drops to 50℃, t: fire extinguishing time.

[0043] Table 1 Measurement results

[0044]

[0045] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. A fire extinguishing agent for heat-sensitive lithium batteries, characterized in that: The raw material components are calculated by weight, including 1-5 parts of surfactant, 10-25 parts of aprotic solvent, 2-5 parts of fire extinguishing agent, 2-5 parts of microcapsule agent, 3-10 parts of temperature reducing agent, 2-10 parts of thermal expansion agent, 1-8 parts of thermal thickener, and 70-100 parts of deionized water; The microcapsule drug is made of perfluorohexanone as the core material, ethyl cellulose as the inner shell material, and SiO2 as the outer shell material; The preparation method of the microcapsule medicament is as follows: (1) After dispersing perfluorohexanone in a solvent, adding an emulsion and blending with high-speed stirring to obtain an emulsion; (2) Under a nitrogen atmosphere, ethyl cellulose, azobisisobutyronitrile, methacrylic acid, and methyl stearate are added to the emulsion, and the reaction system is heated. After the reaction is completed, the pH of the system is adjusted to alkaline, and TEOS is added. After stirring, the microcapsule agent is obtained by filtering, washing, and drying.

2. The fire extinguishing agent for heat-sensitive lithium batteries according to claim 1, characterized in that: The raw material components are calculated by weight and include 2-5 parts of surfactant, 10-15 parts of aprotic solvent, 2-5 parts of fire extinguishing agent, 2-5 parts of microcapsule agent, 3-6 parts of temperature reducing agent, 2-5 parts of thermal expansion agent, 1-3 parts of thermal thickener and 70-80 parts of deionized water.

3. The fire extinguishing agent for heat-sensitive lithium batteries according to claim 1, characterized in that: The surfactant includes at least one of a hydrocarbon surfactant and a fluorine surfactant; the hydrocarbon surfactant includes at least one of sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, and α-olefin sulfonate; the fluorine surfactant includes at least one of perfluorooctane sulfonate, perfluorohexane sulfonate, perfluorooctanoic acid, and perfluorohexanoic acid; and / or the aprotic solvent includes at least one of dimethylacetamide, N,N-dimethylformamide, and hexamethylphosphoramide.

4. The fire extinguishing agent for heat-sensitive lithium batteries according to claim 1, characterized in that: The heat-sensitive expander includes at least one of zeolite, kaolinite, montmorillonite, illite, feldspar, and mica; and / or the heat-sensitive thickener includes at least one of hydroxypropyl methylcellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, and sodium carboxymethyl cellulose.

5. The fire extinguishing agent for heat-sensitive lithium batteries according to claim 1, characterized in that: The fire extinguishing agent includes at least one of potassium dihydroxypropionate, sodium lactate, and calcium propionate; and / or the temperature reducing agent includes at least one of triisopropanolamine, triethylamine, and triethanolamine.

6. The fire extinguishing agent for heat-sensitive lithium batteries according to claim 5, characterized in that: The emulsifier in the emulsion is Tween-80, and the solvent is perfluorocyclic ether.

7. The fire extinguishing agent for heat-sensitive lithium batteries according to claim 5, characterized in that: The mass ratio of perfluorohexanone, ethyl cellulose, methacrylic acid, methyl stearate and TEOS is 50:1:0.2~0.8:0.2~0.5:0.8~1.2, and azobisisobutyronitrile accounts for 1~3wt% of the ethyl cellulose.

8. A method for preparing a fire extinguishing agent for heat-sensitive lithium batteries according to any one of claims 1 to 7, characterized in that: The steps include: (1) Add surfactant, fire extinguishing agent, microcapsule agent, and cooling agent to the aprotic solvent and fully dissolve them; (2) Add the solution obtained in (1) to deionized water and stir evenly; (3) Heating the solution obtained in (2), adding a heat-sensitive thickener and stirring evenly; (4) Cool the solution obtained in (3) to room temperature, add a heat-sensitive expansion agent and stir evenly; (5) The solution obtained in (4) is allowed to stand for defoaming to obtain a fire extinguishing agent.

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