Microcapsulated fire extinguishing agent based on porous material coated modified capsule core, and preparation method and application thereof

Abstract

This invention discloses a microcapsule fire extinguishing agent based on a porous material-coated modified core, its preparation method, and its application. The modified core uses high-temperature resistant attapulgite-based porous ceramic particles coated with perfluorohexanone as the extinguishing medium, and gelatin and gum arabic are used to form the capsule wall. The resulting microcapsule fire extinguishing agent based on a porous material-coated modified core can quickly and effectively extinguish lithium-ion battery fires and effectively control the release rate of the extinguishing medium in the microcapsule fire extinguishing agent. Continuous release of the extinguishing medium inhibits the thermal runaway and reignition of lithium-ion batteries. Using high-temperature attapulgite-based porous ceramic particles to coat the modified core improves the storage stability and transportation stability of the microcapsule fire extinguishing agent, ensuring its safe use.

Description

Technical Field

[0001] This invention belongs to the technical field of fire extinguishing agents for lithium-ion batteries, specifically relating to a microcapsule fire extinguishing agent based on a porous material-coated modified core, its preparation method, and its application. Background Technology

[0002] Lithium-ion batteries, with their advantages of high energy density, no memory effect, good cycle performance, and long lifespan, are widely used in consumer electronics, power system energy storage, and new energy vehicle power systems. However, currently developed lithium-ion batteries have not yet achieved intrinsic safety. When the battery encounters abnormal conditions such as external high temperature, internal short circuit, or overcharging, it can experience thermal runaway due to the large amount of heat generated inside, leading to combustion or even explosion. Effectively solving the safety problems of lithium-ion batteries and promoting their intrinsic safety has become a key research direction for the lithium-ion battery industry.

[0003] Lithium-ion battery fires are characterized by their unique combustion process, rapid fire spread, and difficulty in extinguishing. Simply extinguishing the flames on the surface of the lithium-ion battery cannot fundamentally interrupt the chain decomposition reaction inside the battery. The internal temperature of lithium-ion batteries is usually extremely high, making them prone to reignition. Controlling the thermal runaway and reignition of lithium-ion batteries is an urgent problem to be solved in the current process of fighting lithium-ion battery fires.

[0004] Microencapsulation technology is used to encapsulate extinguishing agents by loading the extinguishing medium as a core into a polymer material capsule wall. Under high-temperature conditions, the capsule wall of the microencapsulated extinguishing agent decomposes, and the extinguishing medium encapsulated inside the microcapsule is rapidly released, extinguishing the flames of the burning material in a short time. It has advantages such as safe use, cleanliness and environmental friendliness, high extinguishing efficiency, and long-term storage. While conventional microencapsulated extinguishing agents can quickly extinguish open flames when used to extinguish lithium-ion battery fires, they are difficult to sustainably and effectively suppress reignition. This is mainly because lithium-ion battery fires are deep-seated fires, requiring high extinguishing agent concentrations and long immersion times to extinguish. Only through continuous release of the extinguishing agent over a long period, ensuring that the internal temperature of the lithium-ion battery drops to a safe range, can reignition be effectively suppressed.

[0005] Therefore, effectively controlling the release rate of the extinguishing medium in microcapsule fire extinguishing agents is key to suppressing the thermal runaway and reignition of lithium-ion batteries. Summary of the Invention

[0006] The purpose of this section is to outline some aspects of embodiments of the present invention and to briefly describe some preferred embodiments. Simplifications or omissions may be made in this section, as well as in the abstract and title of this application, to avoid obscuring the purpose of these documents; however, such simplifications or omissions should not be construed as limiting the scope of the invention.

[0007] In view of the problems existing in the above and / or prior art, the present invention is proposed.

[0008] Therefore, the purpose of this invention is to overcome the shortcomings of the prior art and provide a microcapsule fire extinguishing agent based on a modified capsule core coated with porous material.

[0009] To solve the above-mentioned technical problems, the present invention provides the following technical solution: the microcapsule fire extinguishing agent is composed of a modified capsule core coated with a capsule wall, comprising,

[0010] The modified core is obtained by coating the extinguishing medium perfluorohexanone with high-temperature resistant attapulgite-based porous ceramic particles. The high-temperature resistant attapulgite-based porous ceramic particles are obtained by granulation of attapulgite clay, glass powder and starch. The mass ratio of the high-temperature resistant attapulgite-based porous ceramic particles to perfluorohexanone is 1:0.5 to 1.5.

[0011] The capsule wall is obtained by coagulation of gelatin and gum arabic, wherein the amount of gelatin is 12.5-25% of the mass of perfluorohexanone, the amount of gum arabic is 12.5-25% of the mass of perfluorohexanone, and the ratio of gelatin to gum arabic is 1:1.

[0012] As a preferred embodiment of the microcapsule fire extinguishing agent based on porous material-coated modified core described in this invention, wherein the mass ratio of attapulgite clay, glass powder and starch is 100:10-12:10-30.

[0013] Another objective of this invention is to provide a method for preparing a microcapsule fire extinguishing agent based on a modified core coated with a porous material.

[0014] To solve the above-mentioned technical problems, the present invention provides the following technical solution: including,

[0015] Attapulgite-based porous ceramic particles were ultrasonically dispersed in deionized water to form a uniform suspension. Perfluorohexanone was added to the suspension, and the mixture was then stirred and freeze-dried to obtain a modified core.

[0016] The modified capsule core is mixed and stirred with an emulsifier, and then gelatin solution and gum arabic solution are added sequentially and stirred at high speed to form a homogeneous and stable emulsion. The amount of gelatin is 12.5-25% of the mass of perfluorohexanone, the amount of gum arabic is 12.5-25% of the mass of perfluorohexanone, and the ratio of the amount of gelatin to the amount of gum arabic is 1:1.

[0017] Add glacial acetic acid solution to the above emulsion to adjust the pH value of the emulsion to 3.6-4.0. Carry out the coagulation reaction at a certain coagulation temperature for 1-1.5 hours. After the reaction is completed, wait for the solution system to cool down to 8°C, then add the curing agent, add sodium hydroxide solution to adjust the pH value to 9.0, and carry out the curing reaction for 1-1.5 hours.

[0018] After the curing reaction is completed, a fire extinguishing agent suspension is obtained. After centrifugation, washing, and freeze drying, a microcapsule fire extinguishing agent based on a porous material-coated modified core is obtained.

[0019] As a preferred embodiment of the preparation method of the microcapsule fire extinguishing agent based on porous material-coated modified core according to the present invention, the preparation method of the attapulgite-based porous ceramic particles includes,

[0020] Attapulgite clay, glass powder, and starch are mixed in a mass ratio of 100:10-12:10-30. Water with a mass ratio of 1:1 to attapulgite clay is added and stirred evenly. The mixture is then rolled and granulated in a disc pelletizer. After drying, the mixture is transferred to a muffle furnace and calcined at 500-700℃ for 3 hours. After natural cooling, porous ceramsite based on attapulgite is obtained.

[0021] In a preferred embodiment of the preparation method of the microcapsule fire extinguishing agent based on the porous material-coated modified core described in this invention, the concentrations of the gelatin solution and the arabic solution are both 1-3%.

[0022] As a preferred embodiment of the preparation method of the microcapsule fire extinguishing agent based on porous material-coated modified core according to the present invention, the emulsifier is one or a mixture of several of sodium dodecylbenzenesulfonate, OP-10, FSN-100 or Span 60, and the amount used is 2 to 6% of the mass of perfluorohexanone.

[0023] In a preferred embodiment of the preparation method of the microcapsule fire extinguishing agent based on the porous material-coated modified capsule core described in this invention, the stirring speed of the high-speed stirring is 1500-2500 r / min.

[0024] In a preferred embodiment of the preparation method of the microcapsule fire extinguishing agent based on the porous material-coated modified core of the present invention, the re-condensation temperature of the re-condensation reaction is 35-45℃.

[0025] As a preferred embodiment of the preparation method of the microcapsule fire extinguishing agent based on the porous material-coated modified core of the present invention, the curing agent is ethylenediamine, glutaraldehyde, diethylenetriamine or dicyandiamide, and the amount used is 4-8% of the gelatin.

[0026] Another objective of this invention is to provide an application of microcapsule fire extinguishing agents based on porous material-coated modified cores in the extinguishing of lithium-ion battery fires.

[0027] Beneficial effects of this invention:

[0028] (1) In view of the characteristics of lithium-ion battery fires, the present invention constructs a microcapsule fire extinguishing agent with a modified core coated with a porous polymer material. When the microcapsule fire extinguishing agent is heated, the outer gel decomposes and the modified core inside is released. The release rate of the fire extinguishing medium perfluorohexanone is controlled by the pore structure of the porous material coated with the modified core. It is continuously released through intraparticle pores and interparticle pores, showing the characteristics of being fast at first and then slow, and changing with temperature.

[0029] (2) This invention uses high-temperature resistant attapulgite-based porous ceramic particles as the porous material in the microcapsule fire extinguishing agent. This material has a large specific surface area, high porosity, and a three-dimensional interconnected porous structure combining macropores and micropores, which is beneficial for utilizing the material's thermal conductivity. It also has good adsorption properties, which can inhibit the accumulation of flammable substances generated by the thermal runaway of lithium-ion batteries during the fire extinguishing process through adsorption, further improving the effect of the microcapsule fire extinguishing agent in inhibiting the reignition of lithium-ion batteries due to thermal runaway. Simultaneously, using high-temperature attapulgite-based porous ceramic particles to coat and modify the core can further improve the storage stability and transportation stability of the microcapsule fire extinguishing agent, thereby enhancing its safety in use.

[0030] (3) When the fire extinguishing agent of the present invention is applied to lithium-ion battery fires, it can quickly and effectively extinguish lithium-ion battery fires. At the same time, it can continuously release fire extinguishing media to inhibit the reignition of lithium-ion batteries, thereby effectively solving the problem of reignition of lithium-ion battery thermal runaway fires, ensuring the safety of lithium-ion battery use, and is of great significance to promoting the development of my country's lithium-ion battery industry. Attached Figure Description

[0031] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Wherein:

[0032] Figure 1 This is a SEM image of the product related to Embodiment 1 of the present invention.

[0033] Figure 2 This is a thermogravimetric curve of the product of Example 1 of the present invention. Detailed Implementation

[0034] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the examples in the specification.

[0035] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0036] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that is mutually exclusive with other embodiments.

[0037] Unless otherwise specified, all raw materials used in this invention are commercially available in the art, wherein;

[0038] Attapulgite clay: purchased from Mingguang Guoxing Attapulgite Co., Ltd., 200 mesh powder;

[0039] Glass powder: Commercially available industrial-grade low-melting-point glass powder, 2000 mesh, initial melting temperature 330℃;

[0040] Starch: Purchased from Sinopharm Chemical Reagent Co., Ltd., CAS NO: 9005-84-9, analytical grade.

[0041] Example 1

[0042] This embodiment provides a method for preparing a microcapsule fire extinguishing agent based on a porous material-coated modified core, specifically as follows:

[0043] 1) Attapulgite clay, glass powder and starch are mixed in a mass ratio of 100:10:20. Water with a mass ratio of 1:1 to attapulgite clay is added and stirred evenly. The mixture is rolled and granulated in a disc pelletizer. After drying, it is transferred to a muffle furnace and calcined at 600℃ for 3 hours. After natural cooling, attapulgite-based porous ceramsite is obtained.

[0044] 2) Attapulgite-based porous ceramic particles were ultrasonically dispersed in deionized water to form a uniform suspension. Perfluorohexanone with a mass ratio of 1:1 to the attapulgite-based porous ceramic particles was added to the suspension, stirred for 24 hours, and then freeze-dried to obtain a modified core of attapulgite-based porous ceramic particles coated with perfluorohexanone.

[0045] 3) After the modified capsule core and FSN-100 / OP-10 compound emulsifier (ratio 1:2) are mixed evenly at a mass ratio of 100:2, a 2% gelatin solution and a 2% gum arabic solution are added in sequence. The amount of gelatin and gum arabic is 20% of the mass of perfluorohexanone. The mixture is stirred at a high speed of 2000 r / min for 10 min to form a uniform and stable emulsion.

[0046] 4) Add 10% glacial acetic acid solution to the above emulsion to adjust the pH value of the emulsion to 3.8, and carry out the coagulation reaction at a coagulation temperature of 40℃ for 1 hour.

[0047] 5) After the coagulation reaction is completed, wait for the solution system to cool down to 8°C, add the curing agent diethylenetriamine to the solution system. The amount of curing agent is 6% of the amount of gelatin. Then add 10% sodium hydroxide solution by volume to adjust the pH value of the solution to 9.0 and carry out the curing reaction for 1 hour.

[0048] 6) After the curing reaction is completed, the fire extinguishing agent suspension is obtained. After centrifugation, washing and freeze drying, a microcapsule fire extinguishing agent based on a porous material-coated modified core is obtained.

[0049] Figure 1 The images show the SEM spectra of the modified capsule core and microcapsule fire extinguishing agent prepared in this embodiment. Figure 1 (a) is the SEM image of the modified capsule core coated with perfluorohexanone by attapulgite-based porous ceramic particles obtained in step 2) of this embodiment. It can be seen that the modified capsule core has an irregular wrinkled shape and a rough surface, similar to the surface properties of attapulgite-based porous ceramic particles. It has a well-developed pore structure inside, indicating that the present invention has successfully prepared a modified capsule core by coating perfluorohexanone with attapulgite-based porous ceramic particles. After the microcapsule fire extinguishing agent is decomposed by heat, the release rate of the fire extinguishing medium perfluorohexanone is controlled by the pore structure of the porous material coating the outer layer of the modified capsule core, which can continuously release the fire extinguishing medium and continuously play a role in cooling and fire extinguishing, thereby inhibiting the re-ignition of lithium-ion batteries.

[0050] Figure 1 (b) is the microcapsule fire extinguishing agent produced in this embodiment. It has a regular elongated capsule shape and the microcapsule fire extinguishing agent is dispersed relatively evenly. The capsule wall formed by the coagulation of gelatin and gum arabic is smooth and seamless. The microcapsule structure is complete, indicating that the present invention has successfully prepared a microcapsule fire extinguishing agent with a porous material-coated modified capsule core. The outer capsule wall plays a good protective role for the modified capsule core.

[0051] Figure 2The thermogravimetric curve of the microcapsule fire extinguishing agent produced in this embodiment shows that the extinguishing medium release temperature of the microcapsule fire extinguishing agent prepared in this embodiment is around 200℃. The microcapsule fire extinguishing agent experiences a slight weight loss of about 2% in the temperature range of 40-100℃, mainly due to the loss of moisture in the capsule wall; a weight loss of about 46% in the temperature range of 200-400℃, mainly due to the thermal decomposition of the capsule wall and the slow release of the extinguishing medium; and a weight loss of about 4% in the temperature range of 400-750℃, mainly due to the thermal decomposition of the remaining capsule wall. The thermogravimetric results indicate that in the microcapsule fire extinguishing agent with a porous material-coated modified capsule core prepared in this invention, the capsule wall composed of gelatin and gum arabic successfully encapsulates the modified capsule core, and it does not release the extinguishing medium at lower temperatures, exhibiting good thermal stability.

[0052] Example 2

[0053] The difference from Example 1 is that steps 3) to 5) are specifically as follows:

[0054] 3) After the modified capsule core and OP-10 / FSN-100 compound emulsifier (ratio 1:2) are mixed evenly at a mass ratio of 100:1, a 1% gelatin solution and a 1% gum arabic solution are added sequentially. The amount of gelatin and gum arabic is 12.5% ​​of the mass of perfluorohexanone. The mixture is stirred at a high speed of 1500 r / min for 10 min to form a homogeneous and stable emulsion.

[0055] 4) Add 10% glacial acetic acid solution to the above emulsion to adjust the pH value of the emulsion to 4.0 for re-coagulation. Carry out the re-coagulation reaction at a re-coagulation temperature of 35°C for 1 hour.

[0056] 5) After the coagulation reaction is completed, wait for the solution system to cool down to 8°C, add the curing agent diethylenetriamine to the solution system. The amount of curing agent is 4% of the amount of gelatin. Then add 10% sodium hydroxide solution by volume to adjust the pH value of the solution to 9.0 and carry out the curing reaction for 1 hour.

[0057] The remaining steps are the same as in Example 1, resulting in the microcapsule fire extinguishing agent of this example.

[0058] Example 3

[0059] The difference from Example 1 is that steps 3) to 5) are specifically as follows:

[0060] 3) After the modified capsule core and OP-10 / FSN-100 compound emulsifier (ratio 1:2) are mixed evenly at a mass ratio of 100:3, a 3% gelatin solution and a 3% gum arabic solution are added in sequence. The amount of gelatin and gum arabic is 25% of the mass of perfluorohexanone. The mixture is stirred at a high speed of 2500r / min for 10min to form a uniform and stable emulsion.

[0061] 4) Add 10% glacial acetic acid solution to the above emulsion to adjust the pH value of the emulsion to 3.6. Carry out the coagulation reaction at 45℃ for 1 hour.

[0062] 5) After the coagulation reaction is completed, wait for the solution system to cool down to 8°C, add the curing agent diethylenetriamine to the solution system. The amount of curing agent is 8% of the amount of gelatin. Then add 10% sodium hydroxide solution by volume to adjust the pH value of the solution to 9.0 and carry out the curing reaction for 1 hour.

[0063] The remaining steps are the same as in Example 1, resulting in the microcapsule fire extinguishing agent of this example.

[0064] Example 4

[0065] The difference from Example 2 is that steps 3) and 5) are specifically as follows:

[0066] 3) After the modified capsule core and the emulsifier sodium dodecyl sulfonate are mixed evenly at a mass ratio of 100:1, a 1% gelatin solution and a 1% gum arabic solution are added in sequence. The amount of gelatin and gum arabic is 12.5% ​​of the mass of perfluorohexanone. The mixture is stirred at a high speed of 1500 r / min for 10 min to form a uniform and stable emulsion.

[0067] 5) After the coagulation reaction is completed, wait for the solution system to cool down to 8°C, add the curing agent ethylenediamine to the solution system. The amount of curing agent is 4% of the amount of gelatin. Then add 10% sodium hydroxide solution by volume to adjust the pH value of the solution to 9.0 and carry out the curing reaction for 1 hour.

[0068] The remaining steps are the same as in Example 2, and the microcapsule fire extinguishing agent of this example is obtained.

[0069] Example 5

[0070] The difference from Example 2 is that steps 3) and 5) are specifically as follows:

[0071] 3) After the modified capsule core and emulsifier OP-10 are mixed evenly at a mass ratio of 100:1, a 1% gelatin solution and a 1% gum arabic solution are added in sequence. The amount of gelatin and gum arabic is 12.5% ​​of the mass of perfluorohexanone. The mixture is stirred at a high speed of 1500r / min for 10min to form a uniform and stable emulsion.

[0072] 5) After the coagulation reaction is completed, wait for the solution system to cool down to 8°C, add glutaraldehyde as a curing agent to the solution system. The amount of curing agent is 4% of the amount of gelatin. Then add 10% sodium hydroxide solution by volume to adjust the pH value of the solution to 9.0 and carry out the curing reaction for 1 hour.

[0073] The remaining steps are the same as in Example 2, and the microcapsule fire extinguishing agent of this example is obtained.

[0074] Example 6

[0075] The difference from Example 2 is that steps 3) and 5) are specifically as follows:

[0076] 3) After the modified capsule core and emulsifier Span 60 are mixed evenly at a mass ratio of 100:1, a 1% gelatin solution and a 1% gum arabic solution are added in sequence. The amount of gelatin and gum arabic is 12.5% ​​of the mass of perfluorohexanone. The mixture is stirred at a high speed of 1500 r / min for 10 min to form a uniform and stable emulsion.

[0077] 5) After the coagulation reaction is completed, wait for the solution system to cool down to 8°C, add the curing agent dicyandiamide to the solution system. The amount of curing agent is 4% of the amount of gelatin. Then add 10% sodium hydroxide solution by volume to adjust the pH value of the solution to 9.0 and carry out the curing reaction for 1 hour.

[0078] The remaining steps are the same as in Example 2, and the microcapsule fire extinguishing agent of this example is obtained.

[0079] Example 7

[0080] The difference from Example 3 is that steps 3) and 5) are specifically as follows:

[0081] 3) After the modified capsule core and the emulsifier sodium dodecyl sulfonate are mixed evenly at a mass ratio of 100:3, a 3% gelatin solution and a 3% gum arabic solution are added in sequence. The amount of gelatin and gum arabic is 25% of the mass of perfluorohexanone. The mixture is stirred at a high speed of 2500r / min for 10min to form a uniform and stable emulsion.

[0082] 5) After the coagulation reaction is completed, wait for the solution system to cool down to 8°C, add the curing agent ethylenediamine to the solution system. The amount of curing agent is 8% of the amount of gelatin. Then add 10% sodium hydroxide solution by volume to adjust the pH value of the solution to 9.0 and carry out the curing reaction for 1 hour.

[0083] The remaining steps are the same as in Example 3, and the microcapsule fire extinguishing agent of this example is obtained.

[0084] Example 8

[0085] The difference from Example 3 is that steps 3) and 5) are specifically as follows:

[0086] 3) After the modified capsule core and emulsifier OP-10 are mixed evenly at a mass ratio of 100:3, a 3% gelatin solution and a 3% gum arabic solution are added in sequence. The amount of gelatin and gum arabic is 25% of the mass of perfluorohexanone. The mixture is stirred at a high speed of 2500r / min for 10min to form a uniform and stable emulsion.

[0087] 5) After the coagulation reaction is completed, wait for the solution system to cool down to 8°C, add glutaraldehyde as a curing agent to the solution system. The amount of curing agent is 8% of the amount of gelatin. Then add 10% sodium hydroxide solution by volume to adjust the pH value of the solution to 9.0 and carry out the curing reaction for 1 hour.

[0088] The remaining steps are the same as in Example 3, and the microcapsule fire extinguishing agent of this example is obtained.

[0089] Example 9

[0090] The difference from Example 3 is that steps 3) and 5) are specifically as follows:

[0091] 3) After the modified capsule core and emulsifier Span 60 are mixed evenly at a mass ratio of 100:3, a 3% gelatin solution and a 3% gum arabic solution are added in sequence. The amount of gelatin and gum arabic is 25% of the mass of perfluorohexanone. The mixture is stirred at a high speed of 2500r / min for 10min to form a uniform and stable emulsion.

[0092] 5) After the coagulation reaction is completed, wait for the solution system to cool down to 8°C, add the curing agent dicyandiamide to the solution system. The amount of curing agent is 8% of the amount of gelatin. Then add 10% sodium hydroxide solution by volume to adjust the pH value of the solution to 9.0 and carry out the curing reaction for 1 hour.

[0093] The remaining steps are the same as in Example 3, and the microcapsule fire extinguishing agent of this example is obtained.

[0094] Comparative Example 1

[0095] The difference between this comparative example and Example 1 is that a porous material is not used to encapsulate the modified core. Specifically:

[0096] The fire extinguishing medium perfluorohexanone and FSN-100 / OP-10 compound emulsifier (ratio 1:2) were mixed and stirred at a mass ratio of 100:4. Then, a 2% gelatin solution and a 2% gum arabic solution were added sequentially. The amount of gelatin and gum arabic were both 20% of the mass of perfluorohexanone. The mixture was stirred at a high speed of 2000 r / min for 10 min to form a homogeneous and stable emulsion.

[0097] Add a 10% (v / v) glacial acetic acid solution to the above emulsion to adjust the pH value of the emulsion to 3.8 for re-coagulation. Carry out the re-coagulation reaction at a re-coagulation temperature of 40°C for 1 hour.

[0098] After the coagulation reaction is completed, the solution system is cooled to 8°C, and a curing agent, diethylenetriamine, is added to the solution system. The amount of curing agent is 6% of the amount of gelatin. Then, a 10% sodium hydroxide solution is added dropwise to adjust the pH value of the solution to 9.0. The curing reaction is carried out for 1 hour to obtain a conventional microcapsule fire extinguishing agent suspension. After centrifugation, washing, and freeze drying, conventional microcapsule fire extinguishing agent powder is obtained.

[0099] Performance testing:

[0100] To verify the extinguishing effect of the microcapsule fire extinguishing agent based on porous material-coated modified core prepared in this invention on lithium-ion battery thermal runaway fires and its inhibitory effect on the reignition of lithium-ion battery thermal runaway, this invention conducted fire extinguishing experiments on 18650 standard lithium-ion batteries using the prepared microcapsule fire extinguishing agent:

[0101] First, a heating element was used to simulate heating of a standard 18650 lithium-ion battery to induce thermal runaway. After the lithium-ion battery produced an open flame, a microcapsule extinguishing agent was sprayed to extinguish the fire. The extinguishing agent was released in 8 seconds. The extinguishing effect and the effect of inhibiting reignition are shown in Table 1.

[0102] Table 1

[0103]

[0104]

[0105] As shown in Table 1, the microcapsule fire extinguishing agents prepared in Examples 1-9 can extinguish open flames within 8 seconds and prevent reignition. The microcapsule fire extinguishing agent prepared in Comparative Example 1 also has a good fire extinguishing effect, extinguishing open flames within 4 seconds. However, reignition occurred 118 seconds after the open flames were extinguished. The experiment shows that after the open flames are extinguished, at least 20 seconds of continuous spraying of the fire extinguishing agent is required to completely extinguish the flames and prevent reignition. The microcapsule fire extinguishing agent based on a porous material-coated modified core provided by this invention requires a slightly longer time to extinguish open flames than conventional microcapsule fire extinguishing agents. This is because after the outer capsule wall is decomposed by heat, the release rate of the fire extinguishing medium perfluorohexanone in the porous material-coated modified core is controlled by the pore structure of the high-temperature resistant attapulgite-based porous ceramic particles. It is released through intraparticle and interparticle pores, and its initial release rate is slightly slower than the release rate of the fire extinguishing medium in conventional microcapsule fire extinguishing agents. Therefore, the time required to extinguish open flames is slightly longer. However, conventional microcapsule fire extinguishing agents are difficult to suppress the reignition of lithium-ion batteries in a long-term and efficient manner. The microcapsule fire extinguishing agent based on a porous material-coated modified core provided by this invention can effectively suppress the reignition of lithium-ion batteries. The reason is that the release rate of the fire extinguishing medium perfluorohexanone is controlled by the pore structure of high-temperature attapulgite-based porous ceramic particles. It is released through intraparticle and interparticle pores, exhibiting the characteristics of being fast at first and then slow, and changing with temperature. This achieves the purpose of continuously releasing the fire extinguishing medium to suppress reignition, thereby effectively solving the problem of reignition in lithium-ion battery thermal runaway fires.

[0106] Example 10

[0107] This embodiment was used to investigate the effect of the composite ratio of porous materials on the fire extinguishing performance of the fire extinguishing agent. The difference from Example 1 is that the ratio of attapulgite clay, glass powder and starch was adjusted to 100:12:20, 100:10:10 and 100:10:30 respectively. The remaining steps and processes were the same as in Example 1. Microcapsule fire extinguishing agents with porous material modified cores with different composite ratios were obtained in this embodiment. The fire extinguishing performance was measured and compared with that of Example 1. The results are shown in Table 2.

[0108] Table 2

[0109] The composite ratio of attapulgite clay, glass powder, and starch Firefighting time Whether it reignites 100：10：20 6s No reignition 100：12：20 6s No reignition 100：10：10 7s No reignition 100：10：30 5s No reignition

[0110] The ratio of attapulgite clay, glass powder, and starch affects the compressive strength and porosity of attapulgite-based porous ceramsite. Higher glass powder content results in tighter particle bonding and higher compressive strength, but excessive glass powder content leads to decreased porosity. Similarly, higher starch content increases porosity, but excessive starch content makes granulation difficult. In this embodiment, the glass powder content is 10-12% of the attapulgite clay mass, and the starch content is 10-30% of the attapulgite clay mass. The resulting attapulgite-based porous ceramsite exhibits ideal compressive strength and porosity. Fire extinguishing performance test results show that the microcapsule fire extinguishing agent based on a porous material-coated modified core provided in this embodiment has good fire extinguishing and reignition suppression effects on lithium-ion battery thermal runaway fires.

[0111] Example 11

[0112] This embodiment is used to investigate the effect of the calcination temperature of porous materials on the fire extinguishing performance of fire extinguishing agents. The difference from Example 1 is that the calcination temperature was adjusted to 500℃ and 700℃ respectively. The remaining steps and processes are the same as in Example 1. Microcapsule fire extinguishing agents with porous material modified cores at different calcination temperatures were obtained in this embodiment. The fire extinguishing performance was measured and compared with that of Example 1. The results are shown in Table 3.

[0113] Table 3

[0114] Calcination temperature Firefighting time Whether it reignites 600℃ 6s No reignition 500℃ 6s No reignition 700℃ 6s No reignition

[0115] Preliminary experimental results showed that when the calcination temperature was too low, the compressive strength of the attapulgite-based porous ceramsite was poor, leading to difficulties in molding; when the calcination temperature was too high, the crystal structure of the attapulgite clay was destroyed, resulting in a significant decrease in the specific surface area and porosity of the attapulgite-based porous ceramsite. In this embodiment, the calcination temperature was 500–700℃, and the resulting attapulgite-based porous ceramsite exhibited ideal compressive strength and porosity. Fire extinguishing performance test results showed that the microcapsule fire extinguishing agent based on a porous material-coated modified core provided in this embodiment had good fire extinguishing effect and suppression of reignition in lithium-ion battery thermal runaway fires.

[0116] Example 12

[0117] This embodiment was used to investigate the effect of gelatin / gum arabic concentration on the fire extinguishing performance of the fire extinguishing agent. The difference from Example 1 is that the concentrations of gelatin / gum arabic were adjusted to 1% and 3% respectively. The remaining steps and processes were the same as in Example 1. Microcapsule fire extinguishing agents with different gelatin / gum arabic concentrations were obtained in this embodiment. The fire extinguishing performance was measured and compared with that of Example 1. The results are shown in Table 4.

[0118]

[0119]

[0120] Preliminary experimental results show that the concentration of gelatin / gum arabic has a significant impact on the morphology of microcapsules. Positively charged gelatin and negatively charged gum arabic form the capsule walls through electrostatic interactions. This process mainly depends on the free diffusion of the wall material molecules. Therefore, excessively high or low concentrations of the wall material will affect the free diffusion of the wall material molecules, thus affecting the morphology of the microcapsules. When the gelatin / gum arabic concentration is too low, microcapsules cannot form; when the concentration is too high, the free diffusion of gelatin and gum arabic molecules is hindered, leading to microcapsule adhesion. In this embodiment, the concentration of the gelatin / gum arabic solution is 1–3%. The resulting microcapsules have regular morphologies, exhibiting a regular elongated capsule shape and uniform dispersion. The capsule wall surface formed by the electrostatic interaction of gelatin and gum arabic is smooth and seamless, providing excellent protection for the modified capsule core. Fire extinguishing performance test results show that the microcapsule fire extinguishing agent based on porous material-coated modified capsule core provided in this embodiment has good fire extinguishing effect and suppression of reignition in lithium-ion battery thermal runaway fires.

[0121] Example 13

[0122] This embodiment was used to investigate the effect of gelatin / gum arabic dosage on the fire extinguishing performance of the fire extinguishing agent compared to perfluorohexanone. The difference from Example 1 is that the dosage of gelatin / gum arabic was adjusted to 12.5% ​​and 25% of the mass of perfluorohexanone, respectively. The remaining steps and processes were the same as in Example 1. Microcapsule fire extinguishing agents with different gelatin / gum arabic dosages were obtained in this embodiment. The fire extinguishing performance was measured and compared with that of Example 1. The results are shown in Table 5.

[0123] Table 5

[0124]

[0125] Preliminary experimental results show that the amount of gelatin / gum arabic significantly affects the loading capacity of microcapsules. When the wall material content is too low, the relative amount of the core increases, resulting in a decrease in the density and thickness of the microcapsule walls, leading to a reduction in the compressive strength of the microcapsules, or even preventing microcapsule formation. When the wall material content is too high, the relative amount of the core decreases, resulting in partially hollow microcapsules. In this embodiment, the amount of gelatin / gum arabic is 12.5-25% of the mass of perfluorohexanone. The resulting microcapsules have a regular morphology, good dispersibility, and smooth wall surfaces without obvious gaps, effectively encapsulating the modified core. Fire extinguishing performance test results show that the microcapsule fire extinguishing agent based on porous material-encapsulated modified core provided in this embodiment has good fire extinguishing effect and suppression of reignition in lithium-ion battery thermal runaway fires.

[0126] Example 14

[0127] This embodiment was used to investigate the effect of emulsifier dosage relative to perfluorohexanone dosage on the fire extinguishing performance of the fire extinguishing agent. The difference from Example 1 is that the dosage of emulsifier relative to perfluorohexanone was adjusted to 2% and 6% of the mass of perfluorohexanone, respectively. The remaining steps and processes were the same as in Example 1. Microcapsule fire extinguishing agents with different emulsifier dosages were obtained in this embodiment. The fire extinguishing performance was measured and compared with that of Example 1. The results are shown in Table 6.

[0128] Table 6

[0129] Emulsifier usage compared to perfluorohexanone Firefighting time Whether it reignites 4％ 6s No reignition 2％ 5s No reignition 6％ 6s No reignition

[0130] Preliminary experimental results show that the selection and dosage of emulsifier have a significant impact on the stability of microcapsules. When the emulsifier dosage is too low, the emulsification effect is poor, resulting in uneven microcapsule size and wall thickness, and poor stability. When the emulsifier dosage is too high, the viscosity of the emulsion system becomes too high, causing the microcapsules to agglomerate. In this embodiment, the emulsifier used is a compound emulsifier of FSN-100 / OP-10 (ratio 1:2), with a dosage of 2-6% of the mass of perfluorohexanone. The resulting microcapsules are uniformly dispersed without obvious agglomeration, demonstrating the good emulsification effect of the compound emulsifier. Fire extinguishing performance test results show that the microcapsule fire extinguishing agent based on porous material-coated modified core provided in this embodiment has good fire extinguishing effect and suppression of reignition in lithium-ion battery thermal runaway fires.

[0131] Example 15

[0132] This embodiment was used to investigate the effect of emulsification rate on the fire extinguishing performance of the fire extinguishing agent. The difference from Example 1 is that the emulsification rate was adjusted to 1500 r / min and 2500 rpm respectively. The remaining steps and processes were the same as in Example 1. Microcapsule fire extinguishing agents with different emulsification rates were obtained in this embodiment. The fire extinguishing performance was measured and compared with that of Example 1. The results are shown in Table 7.

[0133] Table 7

[0134] Emulsification speed Firefighting time Whether it reignites 2000r / min 6s No reignition 1500r / min 6s No reignition 2500r / min 6s No reignition

[0135] Preliminary experimental results show that the emulsification rate has a significant impact on the particle size distribution and thermal stability of the microcapsules. When the emulsification rate is too slow, the emulsification effect is poor, resulting in irregular shapes and uneven particle size distribution of the microcapsules, or even failure to form microcapsules at all. As the emulsification rate increases, the particle size of the microcapsules decreases, and the thermal stability increases. However, when the emulsification rate is too high, perfluorohexanone will volatilize in large quantities, leading to a reduction in the loading capacity of the microcapsules. In this embodiment, the emulsification rate is 1500–2500 r / min, resulting in microcapsules with a relatively uniform particle size distribution, intact morphology, and good thermal stability. Fire extinguishing performance test results show that the microcapsule fire extinguishing agent based on a porous material-coated modified core provided in this embodiment has good fire extinguishing effect and suppression of reignition in lithium-ion battery thermal runaway fires.

[0136] Example 16

[0137] This embodiment was used to investigate the effect of complex coagulation pH value on the fire extinguishing performance of the fire extinguishing agent. The difference from Example 1 is that the complex coagulation pH value was adjusted to 3.6 and 4.0 respectively. The remaining steps and processes were the same as in Example 1. Microcapsule fire extinguishing agents with different complex coagulation pH values ​​were obtained in this embodiment. The fire extinguishing performance was measured and compared with that of Example 1. The results are shown in Table 8.

[0138] Table 8

[0139] Complex coagulation pH value Firefighting time Whether it reignites 3.8 6s No reignition 3.6 5s No reignition 4.0 6s No reignition

[0140] Preliminary experimental results show that the pH value of the complex coagulation significantly affects the morphology and loading capacity of the microcapsules. When the pH value is too high, the microcapsules are irregular in shape, unevenly dispersed, and have a low loading capacity. As the pH value of the complex coagulation decreases, the morphology of the microcapsules gradually becomes more regular, and the dispersibility improves. When the pH value is too low, the microcapsules are irregular in shape, the capsule walls become thinner, and even depolymerization occurs, resulting in the inability to form microcapsules. In this embodiment, the pH value of the complex coagulation is 3.6–4.0, and the resulting microcapsules have regular morphology, good dispersibility, and a high loading capacity. The fire extinguishing performance test results show that the microcapsule fire extinguishing agent based on porous material-coated modified capsule core provided in this embodiment has good fire extinguishing effect and suppression of reignition effect on lithium-ion battery thermal runaway fires.

[0141] Example 17

[0142] This embodiment is used to investigate the effect of the re-condensation temperature on the fire extinguishing performance of the fire extinguishing agent. The difference from Example 1 is that the re-condensation temperature is adjusted to 35℃ and 45℃ respectively. The remaining steps and processes are the same as in Example 1. Microcapsule fire extinguishing agents with different re-condensation temperatures are obtained in this embodiment. The fire extinguishing performance is measured and compared with that of Example 1. The results are shown in Table 9.

[0143] Table 9

[0144] Complex condensation temperature Firefighting time Whether it reignites 40℃ 6s No reignition 35℃ 5s No reignition 45℃ 7s No reignition

[0145] The coagulation temperature significantly affects the morphology and loading capacity of microcapsules. At excessively low temperatures, gelatin and gum arabic cannot undergo coagulation, preventing microcapsule formation. At excessively high temperatures, perfluorohexanone volatilizes significantly, reducing the microcapsule loading capacity. In this embodiment, the coagulation temperature is 35–45°C, resulting in microcapsules with regular morphology, uniform particle size distribution, good dispersibility, and high loading capacity. Fire extinguishing performance tests show that the microcapsule fire extinguishing agent based on a porous material-coated modified core provided in this embodiment exhibits good fire extinguishing and reignition suppression effects against lithium-ion battery thermal runaway fires.

[0146] In summary, the microcapsule fire extinguishing agent based on a porous material-coated modified core provided by this invention can rapidly and effectively extinguish lithium-ion battery fires. After the outer capsule wall decomposes under heat, the release rate of the extinguishing medium perfluorohexanone within the porous material-coated modified core is controlled by the pore structure of the high-temperature resistant attapulgite-based porous ceramic particles. Release occurs through intragranular and intergranular pores, allowing the microcapsule fire extinguishing agent provided by this invention to continuously release the extinguishing medium, providing sustained cooling and fire extinguishing effects, and inhibiting the reignition of lithium-ion batteries. This effectively solves the problem of reignition in lithium-ion battery thermal runaway fires. Furthermore, the high-temperature resistant attapulgite-based porous ceramic particles have a large specific surface area, high porosity, and good thermal stability, which can further improve the storage and transportation stability of the microcapsule fire extinguishing agent, enhancing its safety in use.

[0147] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A microcapsule fire extinguishing agent based on a porous material-coated modified core, characterized in that: The microcapsule fire extinguishing agent consists of a modified capsule core encapsulated in a capsule wall, including, The modified core is obtained by coating the fire extinguishing medium perfluorohexanone with high-temperature resistant attapulgite-based porous ceramic particles. The high-temperature resistant attapulgite-based porous ceramic particles are obtained by granulation of attapulgite clay, glass powder and starch. The mass ratio of the high-temperature resistant attapulgite-based porous ceramic particles to perfluorohexanone is 1:0.5 to 1.

5. The capsule wall is obtained by coagulation of gelatin and gum arabic, wherein the amount of gelatin is 12.5-25% of the mass of perfluorohexanone, the amount of gum arabic is 12.5-25% of the mass of perfluorohexanone, and the ratio of gelatin to gum arabic is 1:

1.

2. The microcapsule fire extinguishing agent based on a porous material-coated modified core as described in claim 1, characterized in that: The mass ratio of the attapulgite clay, glass powder, and starch is 100:10-12:10-30.

3. The method for preparing microcapsule fire extinguishing agent based on porous material-coated modified core as described in claim 1 or 2, characterized in that: include, Attapulgite-based porous ceramic particles were ultrasonically dispersed in deionized water to form a uniform suspension. Perfluorohexanone was added to the suspension, and the mixture was then stirred and freeze-dried to obtain a modified core. The modified capsule core is mixed and stirred with an emulsifier, and then gelatin solution and gum arabic solution are added sequentially and stirred at high speed to form a homogeneous and stable emulsion. The amount of gelatin is 12.5-25% of the mass of perfluorohexanone, the amount of gum arabic is 12.5-25% of the mass of perfluorohexanone, and the ratio of the amount of gelatin to the amount of gum arabic is 1:

1. Add glacial acetic acid solution to the above emulsion to adjust the pH value of the emulsion to 3.6-4.

0. Carry out the coagulation reaction at a certain coagulation temperature for 1-1.5 hours. After the reaction is completed, wait for the solution system to cool down to 8°C, then add the curing agent, add sodium hydroxide solution to adjust the pH value to 9.0, and carry out the curing reaction for 1-1.5 hours. After the curing reaction is completed, a fire extinguishing agent suspension is obtained. After centrifugation, washing, and freeze drying, a microcapsule fire extinguishing agent based on a porous material-coated modified core is obtained.

4. The preparation method of the microcapsule fire extinguishing agent based on the porous material-coated modified core as described in claim 3, characterized in that: The preparation method of the attapulgite-based porous ceramic particles includes, Attapulgite clay, glass powder, and starch are mixed in a mass ratio of 100:10-12:10-30. Water with a mass ratio of 1:1 to attapulgite clay is added and stirred evenly. The mixture is then rolled and granulated in a disc pelletizer. After drying, the mixture is transferred to a muffle furnace and calcined at 500-700℃ for 3 hours. After natural cooling, porous ceramsite based on attapulgite is obtained.

5. The preparation method of the microcapsule fire extinguishing agent based on the porous material-coated modified core as described in claim 3, characterized in that: The concentrations of both the gelatin solution and the arabic solution are 1-3%.

6. The method for preparing microcapsule fire extinguishing agent based on porous material-coated modified core as described in claim 3, characterized in that: The emulsifier includes one or a mixture of several of sodium dodecylbenzenesulfonate, OP-10, FSN-100 or Span60, in an amount of 2 to 6% of the mass of perfluorohexanone.

7. The preparation method of the microcapsule fire extinguishing agent based on the porous material-coated modified core as described in claim 3, characterized in that: The stirring speed of the high-speed mixer is 1500-2500 r / min.

8. The preparation method of the microcapsule fire extinguishing agent based on the porous material-coated modified core as described in claim 3, characterized in that: The complex condensation temperature of the complex condensation reaction is 35–45°C.

9. The method for preparing microcapsule fire extinguishing agent based on porous material-coated modified core as described in claim 3, characterized in that: The curing agent includes one or more of ethylenediamine, glutaraldehyde, diethylenetriamine, or dicyandiamide, and is used in an amount of 4-8% of the gelatin.

10. The application of the microcapsule fire extinguishing agent based on a porous material-coated modified core as described in claim 1 or 2 in the firefighting of lithium-ion battery fires.

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