Microcapsule fire extinguishing agent, and preparation method and application thereof

Abstract

The application belongs to the technical field of fire extinguishing, and provides a microcapsule extinguishing agent and a preparation method and application thereof.The microcapsule extinguishing agent is a double-layer microcapsule structure with sodium dodecyl benzene sulfonate functionalized graphene as an outer wall material, hollow microbeads as an inner wall material, and liquid carbon dioxide as a core material.The microcapsule extinguishing agent prepared by the preparation method has good anti-vibration performance, can realize internal fire extinguishing of a lithium battery, is suitable for mobile lithium battery energy storage units such as a vehicle-mounted lithium battery pack, is not prone to losing fire extinguishing effect, and can ensure the safety of the lithium battery during use.

Description

Technical Field

[0001] This application relates to the field of fire extinguishing technology, and in particular to a microcapsule fire extinguishing agent, its preparation method and application. Background Technology

[0002] Common fire extinguishing agents include dry powder, liquid, and gaseous agents. Dry powder agents include ammonium phosphate dry powder, sodium bicarbonate dry powder, Class D dry powder, and ultrafine dry powder with even smaller particle sizes; liquid extinguishing agents include water, aqueous solutions, foam, biological protein extinguishing agents, and ultrafine water mist extinguishing agents; gaseous extinguishing agents include inert gases such as CO2, N2, and IG541, heptafluoropropane extinguishing agents, and thermal aerosol extinguishing agents that have developed rapidly in recent years. Each of these extinguishing agents has its specific application scenarios, and their extinguishing efficiency needs improvement. Existing extinguishing agents cannot fully meet the needs of industrial and public safety.

[0003] For example, containerized lithium battery energy storage systems are based on lithium-ion batteries. Lithium-ion batteries are energy-containing materials and have the inherent danger of fire or explosion. Especially in a confined space, once a fire occurs in one energy storage unit, it will cause a chain reaction of fires in multiple adjacent energy storage units, or even cause the container to explode. The fire load is large, the danger is high, and it is difficult to extinguish.

[0004] Thermal runaway is a critical issue in lithium battery safety research. The key cause of lithium battery fires is internal thermal runaway within the cell, triggered by localized high temperatures that induce internal thermal decomposition reactions, which then spread to nearby cells, leading to a fire. Currently, external fire extinguishing agents, such as aqueous film-forming foam (AFFO), are commonly used to combat lithium battery thermal runaway. However, these agents pose a risk of reignition after a period of time. Furthermore, existing extinguishing agents cannot effectively absorb the toxic gases produced by lithium battery thermal runaway (which contain large amounts of HF gas), failing to fundamentally eliminate potentially explosive ignition sources, making reignition easy after extinguishing. Moreover, while water-based extinguishing agents can dissolve HF gas, they produce large amounts of fluoride-containing solutions. Spraying these extinguishing agents on laptops or electric vehicles using lithium batteries can easily cause short circuits, potentially generating new high-temperature heat sources and exacerbating the fire's spread. Additionally, existing lithium battery fire extinguishing agents primarily provide external suppression and cannot effectively extinguish fires from within.

[0005] Microencapsulation technology is a technique that uses polymeric film-forming materials to encapsulate liquids or solids, forming particles with a core-shell structure. Microencapsulation technology plays a significant role in altering material states to improve their performance, protecting or isolating materials with special functions, and controlling the release of core materials. Therefore, it is gradually being widely applied in the field of fire fighting. In existing technologies, microencapsulated fire extinguishing agents typically consist of a spherical gelatin shell forming a microsphere outer shell, within which a liquid fire extinguishing agent is encapsulated and automatically released upon heating.

[0006] Existing research, such as patent publication number CN108905038B, discloses a microcapsule fire extinguishing agent based on shock wave secondary dispersion and its preparation method. It mainly consists of the following components by weight: 515 parts hollow microspheres, 515 parts iodine nitride, 3050 parts water, 15 parts pore-sealing agent, 3050 parts solid fire extinguishing powder material, and 515 parts microcapsule material. This fire extinguishing agent has a double-layer microcapsule structure. The outermost microcapsule ensures that the physicochemical properties of the fire extinguishing agent are not damaged before covering the combustion zone. After the fire extinguishing agent covers the combustion zone, the solid fire extinguishing powder material between the two microcapsules begins to play a flame-retardant role. Simultaneously, the water in the hollow microspheres evaporates and absorbs heat, reducing the temperature of the combustion zone. When the water has completely evaporated, the iodine nitride in the hollow microspheres explodes upon heating, generating a large amount of nitrogen gas. The shock wave generated by the explosion secondary dispersion of the solid fire extinguishing powder material ensures uniform coverage of the combustion zone. Furthermore, the generated shock wave and nitrogen gas also weaken the combustion reaction and inhibit flame propagation. This microencapsulated fire extinguishing agent has a dual microencapsulation structure. The outer microencapsulation acts as a slow-release agent, allowing the extinguishing agent to reach the center of the fire source smoothly; the inner microencapsulation isolates solid and liquid extinguishing materials, enabling the microencapsulated fire extinguishing agent to exert multiple fire extinguishing functions. However, this microencapsulated fire extinguishing agent uses iodine nitride as an explosive material, which is highly sensitive and explodes upon contact. Although hollow microspheres are used for encapsulation, these microspheres are prone to breakage due to collisions during prolonged vibrations (such as those generated by moving vehicles or ships). Although traditional solid extinguishing powder materials are used to encapsulate the hollow microspheres, these materials do not provide adequate shock resistance. If this microencapsulated fire extinguishing agent is used inside a lithium battery, and the battery is placed in a vehicle or ship, the microencapsulated fire extinguishing agent will spontaneously explode under severe vibrations, losing its fire extinguishing effect. Therefore, it is suitable for external fire extinguishing of static fire sources, limiting its application scope.

[0007] Therefore, if a microcapsule fire extinguishing agent can be provided that can extinguish fires inside lithium batteries and is suitable for use in mobile lithium battery energy storage units such as vehicle-mounted lithium battery packs, and is less likely to lose its fire extinguishing effect, then the safety of lithium battery use can be better guaranteed. Summary of the Invention

[0008] In view of the shortcomings of the prior art, the present invention provides a microcapsule fire extinguishing agent, its preparation method and application, to solve the problems of existing lithium battery fire extinguishing agents mostly extinguishing fires externally and being unable to extinguish fires from the inside in a timely manner; and fire extinguishing agents prepared using hollow microspheres easily losing their fire extinguishing effect due to vibration during transportation.

[0009] To achieve the above and related objectives, the present invention adopts the following technical solution:

[0010] The first aspect of the present invention provides a microcapsule fire extinguishing agent, which is a double-layer microcapsule structure with sodium dodecylbenzenesulfonate functionalized graphene as the outer wall material, hollow microspheres as the inner wall material, and liquid carbon dioxide as the core material.

[0011] A second aspect of the present invention provides a method for preparing a microcapsule fire extinguishing agent, the method comprising the following steps:

[0012] (1) The hollow microsphere monomer is perforated and the inner cavity of the perforated hollow microsphere monomer is filled with liquid carbon dioxide to obtain the crude hollow microsphere product.

[0013] (2) Use adhesive to seal the pores of the hollow microspheres in the coarse product to obtain hollow microspheres with a single-layer microcapsule structure;

[0014] (3) Hollow microspheres were mixed with sodium dodecylbenzenesulfonate functionalized graphene solution, stirred, and coated to obtain a microcapsule fire extinguishing agent with a double-layer microcapsule structure.

[0015] In one embodiment of this application, the preparation method of the sodium dodecylbenzenesulfonate functionalized graphene solution in step (3) includes:

[0016] (a) Water, graphene oxide and sodium dodecylbenzenesulfonate were mixed, stirred, hydrazine was added, heated and stirred, centrifuged, washed with water and dried to obtain sodium dodecylbenzenesulfonate functionalized graphene.

[0017] (b) Dissolve sodium dodecylbenzenesulfonate functionalized graphene in isopropanol to obtain sodium dodecylbenzenesulfonate functionalized graphene solution.

[0018] In one embodiment of this application, the mass ratio of water, graphene oxide, sodium dodecylbenzenesulfonate, and hydrazine in step (a) is (80-120):(4-6):(50-100):(0.03-0.05).

[0019] In one embodiment of this application, step (1) of perforating the hollow microsphere monomer includes:

[0020] Prepare a perforating agent solution by placing hollow microsphere monomers in the perforating agent solution, sealing, stirring, filtering, washing, and drying. The perforating agent is concentrated sulfuric acid or sodium hydroxide.

[0021] In one embodiment of this application, step (1) involves filling the inner cavity of the perforated hollow microsphere monomer with liquid carbon dioxide to obtain a crude hollow microsphere product comprising:

[0022] The perforated hollow microsphere monomers and liquid carbon dioxide were mixed and stirred for 15-30 minutes under a pressure of 5-7 MPa. The mixture was then filtered, washed, filtered again, and dried to obtain the crude hollow microsphere product.

[0023] In one embodiment of this application, step (2) of sealing the pores of the hollow microsphere coarse product with an adhesive to obtain hollow microspheres with a single-layer microcapsule structure includes:

[0024] Prepare an adhesive gel solution, place the crude hollow microsphere product in the adhesive gel solution, stir, filter, and dry to obtain hollow microspheres with a single-layer microcapsule structure, wherein the adhesive is at least one of gelatin, sodium carboxymethyl cellulose, polyurethane, sodium polyacrylate, and chitosan.

[0025] In one embodiment of this application, the mass ratio of the adhesive to the hollow microsphere crude product is 1:(3-5).

[0026] In one embodiment of this application, the mass ratio of hollow microspheres to sodium dodecylbenzenesulfonate functionalized graphene solution in step (3) is (5-15):(60-70).

[0027] A third aspect of the present invention provides a lithium battery in which a microcapsule fire extinguishing agent is disposed inside. The microcapsule fire extinguishing agent is the microcapsule fire extinguishing agent as described above, or is a microcapsule fire extinguishing agent prepared by the method described above.

[0028] The beneficial technical effects of this invention are as follows:

[0029] This application utilizes liquid carbon dioxide as the core material, hollow microspheres as the inner wall material, and sodium dodecylbenzenesulfonate-functionalized graphene as the outer wall material to prepare a microcapsule fire extinguishing agent with a double-layer microcapsule structure. This agent is suitable for extinguishing fires inside lithium batteries and exhibits good stability, making it less prone to loss of extinguishing effect due to vibration or collision during the transportation of lithium batteries. When a lithium battery experiences thermal runaway, the microcapsule fire extinguishing agent activates, causing the liquid carbon dioxide to explode upon heating, generating carbon dioxide gas to extinguish the fire. Furthermore, the synergistic effect of the hollow microspheres and sodium dodecylbenzenesulfonate-functionalized graphene further enhances the flame-retardant effect, resulting in high fire extinguishing efficiency. This agent is suitable for large-scale series and parallel lithium battery energy storage units and has no impact on the internal structure of the lithium battery.

[0030] This application uses liquid carbon dioxide as the core material, filled within hollow microspheres. When a lithium battery experiences thermal runaway, a large amount of heat is generated inside. The liquid carbon dioxide absorbs heat and vaporizes, rapidly expanding to generate high pressure that impacts the hollow microspheres, releasing it and thus extinguishing any internal fire source. Simultaneously, under the impact of the carbon dioxide gas, the sodium dodecylbenzenesulfonate functionalized graphene coating the hollow microspheres is dispersed, thereby covering the internal fire source for secondary extinguishing.

[0031] Hollow microspheres are an ideal low-density fire extinguishing agent, but they need to maintain their intact structure to be effective. Therefore, hollow microspheres need to be coated to ensure their structural integrity when not in use. Graphene possesses excellent mechanical strength in a two-dimensional plane and is a good refractory material, suitable for lithium batteries. Therefore, this application uses graphene to coat the surface of hollow microspheres to improve their mechanical properties. Simultaneously, this application uses sodium dodecylbenzenesulfonate to functionalize graphene oxide. Sodium dodecylbenzenesulfonate is a surfactant with good foaming properties, which can improve the strong defoaming effect of graphene. Under the action of the reducing agent hydrazine, it is reduced to graphene, making the functionalized graphene made with sodium dodecylbenzenesulfonate more stable.

[0032] In summary, the microcapsule fire extinguishing agent prepared by the method of this application has good vibration resistance, can extinguish fires inside lithium batteries, and is suitable for mobile lithium battery energy storage units such as vehicle-mounted lithium battery packs. It is not easy to lose its fire extinguishing effect and can ensure the safety of lithium batteries during use.

[0033] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and do not limit this application. Detailed Implementation

[0034] Unless otherwise defined, all technical and / or scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. It should be understood that certain features of the invention (described in the context of separate embodiments for clarity) may also be provided in combination in a single embodiment. Conversely, multiple features of the invention (described in the context of a single embodiment for brevity) may also be provided separately or in any suitable combination or, where appropriate, in any other described embodiment of the invention. Certain features described in the context of various embodiments will not be considered essential features of those embodiments unless the embodiment is inoperable without those elements. The invention is further illustrated below by specific examples; however, it should be noted that the specific process conditions and results described in the embodiments of the invention are merely illustrative and should not be construed as limiting the scope of protection of the invention. All equivalent changes or modifications made in accordance with the spirit and essence of the invention should be covered within the scope of protection of the invention.

[0035] This invention provides a microcapsule fire extinguishing agent, which has a double-layer microcapsule structure with sodium dodecylbenzenesulfonate functionalized graphene as the outer wall material, hollow microspheres as the inner wall material, and liquid carbon dioxide as the core material.

[0036] This invention also provides a method for preparing a microcapsule fire extinguishing agent, the method comprising the following steps:

[0037] (1) Prepare a perforating agent solution with a concentration of 0.5-0.8 mol / L. The perforating agent is concentrated sulfuric acid or sodium hydroxide. Place the hollow microspheres in the perforating agent solution, seal, and magnetically stir for 15-30 min at a speed of 400-600 rpm. After stirring, filter, wash, and dry to obtain the perforated hollow microsphere monomer.

[0038] Perforated hollow microsphere monomers and liquid carbon dioxide were mixed and added to a high-pressure reactor. The mixture was magnetically stirred for 15–30 minutes at 1600–2000 rpm under a pressure of 5–7 MPa at room temperature. After stirring, the mixture was filtered, washed, filtered again, and dried to obtain the crude hollow microsphere product. The amount of liquid carbon dioxide used was sufficient to impregnate all the perforated hollow microspheres participating in the reaction.

[0039] (2) Prepare an adhesive gel solution with a viscosity of 20–40 mPa·s. The adhesive is at least one of gelatin, sodium carboxymethyl cellulose, polyurethane, sodium polyacrylate, and chitosan. Place the crude hollow microsphere product in the adhesive solution, stir rapidly at room temperature for 5–10 min, filter, and dry to obtain hollow microspheres with a single-layer microcapsule structure. The mass ratio of adhesive to crude hollow microsphere product is 1:(3–5).

[0040] (3) Select water, graphene oxide, sodium dodecylbenzenesulfonate, and hydrazine in a mass ratio of (80-120):(4-6):(50-100):(0.03-0.05). Mix water, graphene oxide, and sodium dodecylbenzenesulfonate, and stir magnetically at room temperature for 30-40 minutes at a speed of 1000-1500 rpm. Add hydrazine, and stir magnetically at 80℃ for 20-24 hours. Centrifuge, wash three times with distilled water, and dry at 60℃ to obtain sodium dodecylbenzenesulfonate functionalized graphene.

[0041] Sodium dodecylbenzenesulfonate functionalized graphene was dissolved in isopropanol to prepare a sodium dodecylbenzenesulfonate functionalized graphene solution with a concentration of 3-5 mol / L.

[0042] Hollow microspheres and sodium dodecylbenzenesulfonate functionalized graphene solution were mixed in a mass ratio of (5-15):(60-70), stirred at room temperature for 4-8 hours, coated, and allowed to stand for 1-2 hours. The bottom layer solution was then removed to obtain a microcapsule fire extinguishing agent with a double-layer microcapsule structure.

[0043] The present invention also provides a lithium battery having a microcapsule fire extinguishing agent disposed inside, wherein the microcapsule fire extinguishing agent is the microcapsule fire extinguishing agent as described above, or is a microcapsule fire extinguishing agent prepared by the method described above.

[0044] The present invention will be described in detail below through specific examples and embodiments. It should also be understood that the following embodiments are only for specific illustration of the present invention and should not be construed as limiting the scope of protection of the present invention. Any non-essential improvements and adjustments made by those skilled in the art based on the above description of the present invention are within the scope of protection of the present invention. The specific process parameters, etc., in the following examples are merely examples within a suitable range; that is, those skilled in the art can make appropriate selections within the appropriate range based on the description herein, and are not intended to be limited to the specific values ​​in the examples below.

[0045] Example 1

[0046] (1) Prepare a sodium hydroxide solution with a concentration of 0.5 mol / L. Place the hollow microspheres in the sodium hydroxide solution, seal, and magnetically stir for 20 min at a speed of 400 rpm. After stirring, filter, wash, and dry to obtain perforated hollow microsphere monomers;

[0047] The perforated hollow microsphere monomer and liquid carbon dioxide were mixed and added to a high-pressure reactor. The mixture was magnetically stirred for 20 minutes at 1600 rpm under a pressure of 5 MPa and at room temperature. After stirring, the mixture was filtered, washed, filtered again, and dried to obtain the crude hollow microsphere product.

[0048] (2) Prepare a polyurethane gel solution with a viscosity of 20 mPa·s. Place the crude hollow microsphere product into the polyurethane gel solution, stir rapidly for 7 min at room temperature, filter, and dry to obtain hollow microspheres with a single-layer microcapsule structure. The mass ratio of adhesive to crude hollow microsphere product is 1:3.

[0049] (3) Select water, graphene oxide, sodium dodecylbenzenesulfonate, and hydrazine in a mass ratio of 100:5:60:0.03. Mix water, graphene oxide, and sodium dodecylbenzenesulfonate, and stir magnetically for 30 min at room temperature at a speed of 1200 rpm. Add hydrazine, and stir magnetically at a constant temperature of 80℃ for 24 h. Centrifuge, wash three times with distilled water, and dry at 60℃ to obtain sodium dodecylbenzenesulfonate functionalized graphene.

[0050] Sodium dodecylbenzenesulfonate functionalized graphene was dissolved in isopropanol to prepare a 3 mol / L sodium dodecylbenzenesulfonate functionalized graphene solution.

[0051] Hollow microspheres and sodium dodecylbenzenesulfonate functionalized graphene solution were mixed at a mass ratio of 10:60, stirred at room temperature for 5 hours, coated, and allowed to stand for 1 hour to remove the bottom layer solution, thus obtaining a microcapsule fire extinguishing agent with a double-layer microcapsule structure.

[0052] Example 2

[0053] (1) Prepare a sulfuric acid solution with a concentration of 0.6 mol / L. Place the hollow microspheres in the sulfuric acid solution, seal, and magnetically stir for 20 min at a speed of 500 rpm. After stirring, filter, wash, and dry to obtain perforated hollow microsphere monomers;

[0054] The perforated hollow microsphere monomer and liquid carbon dioxide were mixed and added to a high-pressure reactor. Under a pressure of 6 MPa and at room temperature, the mixture was magnetically stirred for 15 minutes at a speed of 1800 rpm. After stirring, the mixture was filtered, washed, filtered again, and dried to obtain the crude hollow microsphere product.

[0055] (2) Prepare a chitosan gel solution with a viscosity of 30 mPa·s. Place the crude hollow microsphere product into the chitosan gel solution, stir rapidly for 7 min at room temperature, filter, and dry to obtain hollow microspheres with a single-layer microcapsule structure. The mass ratio of the adhesive to the crude hollow microsphere product is 1:4.

[0056] (3) Select water, graphene oxide, sodium dodecylbenzenesulfonate, and hydrazine in a mass ratio of 120:6:80:0.05. Mix water, graphene oxide, and sodium dodecylbenzenesulfonate, and stir magnetically for 30 min at room temperature at a speed of 1500 rpm. Add hydrazine, and stir magnetically at a constant temperature of 80℃ for 24 h. Centrifuge, wash three times with distilled water, and dry at 60℃ to obtain sodium dodecylbenzenesulfonate functionalized graphene.

[0057] Sodium dodecylbenzenesulfonate functionalized graphene was dissolved in isopropanol to prepare a 4 mol / L sodium dodecylbenzenesulfonate functionalized graphene solution.

[0058] Hollow microspheres and sodium dodecylbenzenesulfonate functionalized graphene solution were mixed at a mass ratio of 8:60, stirred at room temperature for 6 hours, coated, and allowed to stand for 1 hour to remove the bottom layer solution, thus obtaining a microcapsule fire extinguishing agent with a double-layer microcapsule structure.

[0059] Example 3

[0060] (1) Prepare a sulfuric acid solution with a concentration of 0.8 mol / L. Place the hollow microspheres in the sulfuric acid solution, seal, and stir magnetically for 30 min at a speed of 400 rpm. After stirring, filter, wash, and dry to obtain perforated hollow microsphere monomers;

[0061] The perforated hollow microsphere monomer and liquid carbon dioxide were mixed and added to a high-pressure reactor. The mixture was magnetically stirred for 30 minutes at 1600 rpm under a pressure of 7 MPa and at room temperature. After stirring, the mixture was filtered, washed, filtered again, and dried to obtain the crude hollow microsphere product.

[0062] (2) Prepare a chitosan gel solution with a viscosity of 35 mPa·s. Place the crude hollow microsphere product into the chitosan gel solution, stir rapidly for 7 min at room temperature, filter, and dry to obtain hollow microspheres with a single-layer microcapsule structure. The mass ratio of the adhesive to the crude hollow microsphere product is 1:3.

[0063] (3) Select water, graphene oxide, sodium dodecylbenzenesulfonate, and hydrazine in a mass ratio of 100:5:80:0.05. Mix water, graphene oxide, and sodium dodecylbenzenesulfonate, and stir magnetically for 30 min at room temperature at a speed of 1500 rpm. Add hydrazine, and stir magnetically at a constant temperature of 80℃ for 24 h. Centrifuge, wash three times with distilled water, and dry at 60℃ to obtain sodium dodecylbenzenesulfonate functionalized graphene.

[0064] Sodium dodecylbenzenesulfonate functionalized graphene was dissolved in isopropanol to prepare a 5 mol / L sodium dodecylbenzenesulfonate functionalized graphene solution.

[0065] Hollow microspheres and sodium dodecylbenzenesulfonate functionalized graphene solution were mixed at a mass ratio of 15:70, stirred at room temperature for 5 hours, coated, and allowed to stand for 1 hour to remove the bottom layer solution, thus obtaining a microcapsule fire extinguishing agent with a double-layer microcapsule structure.

[0066] Comparative Example 1

[0067] The difference between this comparative example and Example 1 is that hollow microspheres were directly coated with graphene solution to obtain microcapsule fire extinguishing agent.

[0068] Comparative Example 2

[0069] The difference between this comparative example and Example 1 is that hollow microspheres are directly coated with solid fire extinguishing powder material to obtain microcapsule fire extinguishing agent.

[0070] Comparative Example 3

[0071] The difference between this comparative example and Example 1 is that an aqueous solution of nitrogen iodide is used as the core material.

[0072] Comparative Example 4

[0073] The difference between this comparative example and Example 1 is that the hollow microspheres are not coated with sodium dodecylbenzenesulfonate functionalized graphene.

[0074] Performance testing

[0075] Fire extinguishing performance: Twelve test lithium batteries were connected in parallel and placed on a heating plate with a power of 1kW, a temperature of 600℃, and dimensions of 210mm×170mm×15mm. The batteries were charged to 100% SOC and then the power was turned off. The heating plate was heated uniformly at a rate of 20℃ / min. Twenty seconds after the battery thermally ran away and its casing burst, the heating plate was sprayed with microcapsule fire extinguishing agents from Examples 1-3 and Comparative Examples 1-2 of this application. The time required to extinguish the open flame and whether reignition occurred after 1 minute were measured. The test results are shown in Table 1. (The lithium batteries used in this test are soft-pack ternary lithium-ion NCM811 / graphite system power batteries, with an aluminum outer film.)

[0076] Shock resistance: The shock resistance of the microcapsule fire extinguishing agents in Example 1 and Comparative Examples 3-4 was tested by treating them in an ultrasonic water tank for 2 hours to simulate the vibration of a moving vehicle or ship. The weight ratios of the microcapsule fire extinguishing agents floating, suspended, and sinking in the ultrasonic water tank are shown in Table 2.

[0077] Table 1. Fire extinguishing performance of microencapsulated fire extinguishing agents in Examples 1-3 and Comparative Examples 1-2

[0078] Test object Time to extinguish open flames / s reignition Example 1 59 no Example 2 56 no Example 3 48 no Comparative Example 1 96 no Comparative Example 2 67 yes

[0079] As shown in Table 1, the microcapsule fire extinguishing agents of Examples 1-3 of this application can achieve rapid fire extinguishing within 1 minute and prevent reignition when lithium battery thermal runaway occurs. This indicates that the microcapsule fire extinguishing agents of this application have the advantages of high-efficiency fire extinguishing and good anti-burning performance. Although the microcapsule fire extinguishing agent of Comparative Example 1 can also achieve the effect of preventing reignition, its fire extinguishing speed is slow. This is because the graphene is not modified and has a strong foam-eliminating effect, which affects the fire extinguishing speed. Although the microcapsule fire extinguishing agent of Comparative Example 1 can also achieve rapid fire extinguishing in about 1 minute, it is prone to reignition and has poor anti-burning performance.

[0080] Table 2. Earthquake resistance of microencapsulated fire extinguishing agents in Examples 1 and Comparative Examples 3-4

[0081]

[0082]

[0083] As shown in Table 2, the microcapsule fire extinguishing agent prepared in this application still retains its fire extinguishing effect under continuous vibration and exhibits good seismic resistance. In contrast, the microcapsule fire extinguishing agent in Comparative Example 4, which is not coated with sodium dodecylbenzenesulfonate functionalized graphene, has poor mechanical strength; under continuous vibration, approximately 30% of the hollow microspheres collide and lose their fire extinguishing effect. Furthermore, the microcapsule fire extinguishing agent in Comparative Example 3, prepared using nitrogen iodide aqueous solution as the core material, exhibits high sensitivity to nitrogen iodide under continuous vibration and is prone to spontaneous explosion, thus rendering the microcapsule fire extinguishing agent ineffective. Therefore, its seismic resistance is lower than that of the microcapsule fire extinguishing agent in this application.

[0084] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person 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 microencapsulated fire extinguishing agent, characterized in that, The microcapsule extinguishing agent is a double-layer microcapsule structure with sodium dodecyl benzene sulfonate functionalized graphene as an outer wall material, hollow microbeads as an inner wall material, and liquid carbon dioxide as a core material. The preparation method of the microcapsule extinguishing agent comprises the following steps: (1) perforating the hollow microbead monomers, filling the inner cavities of the perforated hollow microbead monomers with liquid carbon dioxide to obtain a hollow microbead crude product; (2) plugging the pores of the hollow microbead crude product with an adhesive to obtain hollow microbeads with a single-layer microcapsule structure; (3) mixing the hollow microbeads with a sodium dodecyl benzene sulfonate functionalized graphene solution, stirring, and coating to obtain a microcapsule extinguishing agent with a double-layer microcapsule structure; The preparation method of the sodium dodecyl benzene sulfonate functionalized graphene solution comprises: (a) mixing water, graphene oxide, and sodium dodecyl benzene sulfonate, stirring, adding hydrazine, heating and stirring, centrifuging, washing with water, and drying to obtain sodium dodecyl benzene sulfonate functionalized graphene; wherein the mass ratio of water, graphene oxide, sodium dodecyl benzene sulfonate, and hydrazine is (80-120):(4-6):(50-100):(0.03-0.05); (b) dissolving the sodium dodecyl benzene sulfonate functionalized graphene in isopropyl alcohol to obtain a sodium dodecyl benzene sulfonate functionalized graphene solution.

2. A process for the preparation of microencapsulated fire extinguishing agent, characterized in that, The method comprises the following steps: (1) perforating the hollow microbead monomers, filling the inner cavities of the perforated hollow microbead monomers with liquid carbon dioxide to obtain a hollow microbead crude product; (2) plugging the pores of the hollow microbead crude product with an adhesive to obtain hollow microbeads with a single-layer microcapsule structure; (3) mixing the hollow microbeads with a sodium dodecyl benzene sulfonate functionalized graphene solution, stirring, and coating to obtain a microcapsule extinguishing agent with a double-layer microcapsule structure; The preparation method of the sodium dodecyl benzene sulfonate functionalized graphene solution comprises: (a) mixing water, graphene oxide, and sodium dodecyl benzene sulfonate, stirring, adding hydrazine, heating and stirring, centrifuging, washing with water, and drying to obtain sodium dodecyl benzene sulfonate functionalized graphene; wherein the mass ratio of water, graphene oxide, sodium dodecyl benzene sulfonate, and hydrazine is (80-120):(4-6):(50-100):(0.03-0.05); (b) dissolving the sodium dodecyl benzene sulfonate functionalized graphene in isopropyl alcohol to obtain a sodium dodecyl benzene sulfonate functionalized graphene solution.

3. The method for preparing the microcapsule fire extinguishing agent according to claim 2, characterized in that, The step (1) of perforating the hollow microbead monomers comprises: Preparation of a perforating agent solution, placing the hollow microbead monomers in the perforating agent solution, sealing, stirring, filtering, washing, and drying, wherein the perforating agent is concentrated sulfuric acid or sodium hydroxide.

4. The method of claim 2, wherein the microencapsulated fire extinguishing agent is prepared by the steps of: The step (1) of filling the inner cavities of the perforated hollow microbead monomers with liquid carbon dioxide to obtain a hollow microbead crude product comprises: Mixing the perforated hollow microbead monomers and liquid carbon dioxide, stirring for 15-30 minutes under a pressure of 5-7 MPa, filtering, washing, filtering, and drying to obtain a hollow microbead crude product.

5. The method of claim 2, wherein the microencapsulated fire extinguishing agent is prepared by the steps of: The step (2) of plugging the pores of the hollow microbead crude product with an adhesive to obtain hollow microbeads with a single-layer microcapsule structure comprises: The adhesive glue solution is prepared, the hollow microsphere crude product is placed in the adhesive glue solution, stirred, filtered, and dried to obtain the hollow microsphere with a single-layer microcapsule structure, wherein the adhesive is at least one of gelatin, sodium hydroxymethyl cellulose, polyurethane, polyacrylic acid sodium, and chitosan.

6. The method of claim 5, wherein the microencapsulated fire extinguishing agent is prepared by the process of: The mass ratio of the adhesive to the hollow microsphere crude product is 1: (3-5).

7. The method of claim 2, wherein the microencapsulated fire extinguishing agent is prepared by the steps of: The mass ratio of the hollow microsphere to the sodium dodecyl benzene sulfonate functionalized graphene solution in the step (3) is (5-15):(60-70).

8. A lithium battery, characterized by The lithium battery is internally provided with the microcapsule fire extinguishing agent, and the microcapsule fire extinguishing agent is the microcapsule fire extinguishing agent according to claim 1 or the microcapsule fire extinguishing agent prepared by the preparation method of any one of claims 2-7.

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