A halogen-free composite lithium battery solid fire extinguishing agent and its preparation method

Abstract

This invention relates to a halogen-free composite lithium battery solid fire extinguishing agent and its preparation method. The preparation method includes: adding vinyltriethoxysilane to ethanol to obtain a mixture; adding poly(bis(2-methoxyethoxy)phosphazene) and inorganic filler to the mixture to obtain a reaction solution; stirring the reaction solution; and drying to obtain the halogen-free composite lithium battery solid fire extinguishing agent. The inorganic filler includes nano-magnesium hydroxide. In this invention, poly(bis(2-methoxyethoxy)phosphazene) containing nitrogen and phosphorus synergistic flame-retardant groups and inorganic filler including nano-magnesium hydroxide are coupled together by vinyltriethoxysilane. When the halogen-free composite lithium battery solid fire extinguishing agent prepared by this invention extinguishes a fire, the phosphonic acid derivatives produced by the thermal decomposition of the bis(2-methoxyethoxy)phosphazene groups react with the magnesium oxide produced by the thermal decomposition of magnesium hydroxide to generate solid magnesium salts. These solid magnesium salts isolate heat transfer and oxygen, thereby further enhancing the fire extinguishing effect.

Description

Technical Field

[0001] This invention belongs to the field of fire extinguishing agent technology, specifically relating to a halogen-free composite lithium battery solid fire extinguishing agent and its preparation method. Background Technology

[0002] In recent years, with the widespread use of mobile devices and the increasing market share of new energy vehicles, lithium batteries have become an indispensable energy storage device in people's daily lives. However, the safety issues that come with them, especially fire hazards, cannot be ignored. Lithium batteries have high combustion temperatures and fast combustion rates, producing large amounts of toxic and harmful gases, making fires difficult to extinguish, and posing a risk of explosion during combustion.

[0003] However, most existing lithium battery fire extinguishing agents can only extinguish open flames and cannot effectively prevent repeated reignition of lithium batteries.

[0004] To solve the above technical problems, patent document CN111905317A discloses a method for preparing a nano-dispersed lithium battery fire extinguishing agent, comprising: (1) reacting polyvinyl alcohol and benzyl chloride under alkaline conditions to prepare a derivative polyvinyl alcohol benzyl chloride; (2) dissolving the derivative polyvinyl alcohol benzyl chloride in a solvent, and then adding a tertiary amine to carry out an amination reaction to prepare a nitrogen-based flame retardant fire extinguishing agent prepolymer solution; (3) concentrating the nitrogen-based flame retardant fire extinguishing agent prepolymer solution under vacuum rotary steam. (3) The nitrogen-based flame retardant fire extinguishing agent was then washed and distilled to prepare a nitrogen-based flame retardant fire extinguishing agent; (4) Clay minerals were dispersed in water with a magnetic rod to prepare a clay suspension. The nitrogen-based flame retardant fire extinguishing agent was then diluted with a solvent and mixed with the clay suspension. After sonication, a flame retardant suspension was formed; (5) The flame retardant suspension was stirred and repeatedly centrifuged and washed. Then, it was freeze-dried to prepare a clay flame retardant fire extinguishing agent powder; (6) The clay flame retardant fire extinguishing agent powder was ball-milled and sieved to prepare a nano-dispersed lithium battery fire extinguishing agent. The nano-dispersed lithium battery fire extinguishing agent prepared by this method contains a self-synthesized nitrogen-based flame retardant fire extinguishing agent, which contains flame retardant groups and endothermic degradation groups. While extinguishing open flames, it can significantly reduce the ambient temperature, prevent repeated reignition of lithium batteries, and has a long storage time. However, the nano-dispersed lithium battery fire extinguishing agent prepared by this method uses halogens as flame retardant groups, which is not environmentally friendly. Summary of the Invention

[0005] In view of this, the purpose of this invention is to provide a halogen-free composite lithium battery solid fire extinguishing agent and its preparation method, so as to solve the technical problems of existing lithium battery fire extinguishing agents, which can only extinguish open flames and cannot effectively prevent repeated reignition of lithium batteries; and nano-dispersed lithium battery fire extinguishing agents, which use halogens as flame retardant groups and are not environmentally friendly.

[0006] In some embodiments, the present invention provides a method for preparing a halogen-free composite lithium battery solid fire extinguishing agent, comprising:

[0007] Vinyltriethoxysilane was added to ethanol to obtain a mixture. Poly(bis(2-methoxyethoxy)phosphazene) and inorganic filler were added to the mixture to obtain a reaction solution. The mixture was stirred and dried to obtain the halogen-free composite lithium battery solid fire extinguishing agent. The inorganic filler included nano-magnesium hydroxide.

[0008] In this invention, poly(bis(2-methoxyethoxy)phosphazene) containing nitrogen- and phosphorus-synergistic flame-retardant groups and inorganic fillers including nano-magnesium hydroxide are coupled together using vinyltriethoxysilane. When the halogen-free composite lithium battery solid fire extinguishing agent prepared using this method extinguishes a fire, the phosphonic acid derivatives produced by the thermal decomposition of the bis(2-methoxyethoxy)phosphazene groups react with the magnesium oxide produced by the thermal decomposition of magnesium hydroxide to form solid magnesium salts. These solid magnesium salts isolate heat transfer and oxygen, thereby further enhancing the fire extinguishing effect. Simultaneously, the phosphorus-containing groups in the poly(bis(2-methoxyethoxy)phosphazene) can absorb the heat released during combustion. This process lowers the temperature of the combustion zone and slows down the combustion rate. The nitrogen-containing groups in poly(bis(2-methoxyethoxy)phosphazene) absorb a large amount of heat during decomposition, further reducing the temperature of the combustion zone and slowing down the combustion rate, thus enhancing the fire extinguishing effect. Magnesium hydroxide also absorbs a large amount of heat during thermal decomposition, further enhancing the fire extinguishing effect. Furthermore, by coupling poly(bis(2-methoxyethoxy)phosphazene) containing nitrogen and phosphorus synergistic flame-retardant groups with inorganic fillers including nano-magnesium hydroxide using vinyltriethoxysilane, the agglomeration of nano-magnesium hydroxide is avoided, further improving the fire extinguishing effect. It is also halogen-free, making it safe and environmentally friendly.

[0009] In some embodiments, the temperature of the stirring reaction is 90-100°C, preferably 95-100°C; the pressure of the stirring reaction is 3-6 MPa, preferably 4-6 MPa; and the duration of the stirring reaction is 1-3 h, preferably 1.5-3 h.

[0010] In some embodiments, the particle size of the nano-magnesium hydroxide is 50-100 nm, preferably 50-90 nm.

[0011] In some embodiments, the mass ratio of vinyltriethoxysilane to inorganic filler is 0.01-0.02:1, preferably 0.015-0.02:1.

[0012] In some embodiments, the mass ratio of the inorganic filler to poly(bis(2-methoxyethoxy)phosphazene) is 0.3-0.5:1, preferably 0.35-0.5:1.

[0013] In some embodiments, the inorganic filler further includes nano-silica.

[0014] In some embodiments, the particle size of the nano-silica is 20-100 nm, preferably 30-100 nm.

[0015] In some embodiments, the mass ratio of nano-silica to nano-magnesium hydroxide is 1-2:3-4, preferably 1.5-2:3-4.

[0016] In this invention, nano-silica can enhance the thermal stability of the char layer formed during combustion, thereby further improving the fire extinguishing effect.

[0017] In some embodiments, the reaction solution further includes zinc borate.

[0018] In some embodiments, the mass ratio of zinc borate to nano-magnesium hydroxide is 3-4:1, preferably 3.5-4:1.

[0019] In this invention, zinc borate can form an inorganic ceramic-like carbonized layer with magnesium oxide, a thermal decomposition product of nano-magnesium hydroxide, during combustion, thereby blocking the transfer of heat and oxygen and further improving the fire extinguishing effect.

[0020] In some embodiments, the present invention also provides a halogen-free composite lithium battery solid fire extinguishing agent prepared according to the preparation method described above. Detailed Implementation

[0021] The present invention will be further illustrated by specific examples below. However, it should be noted that the specific material ratios, process conditions and results described in the embodiments of the present invention are only for illustrating the present invention and cannot be used to limit the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

[0022] This invention provides a method for preparing a halogen-free composite lithium battery solid fire extinguishing agent, comprising:

[0023] Vinyltriethoxysilane was added to ethanol to obtain a mixture. Poly(bis(2-methoxyethoxy)phosphazene) and inorganic filler were added to the mixture to obtain a reaction solution. The mass ratio of vinyltriethoxysilane to inorganic filler was 0.01-0.02:1, and the mass ratio of inorganic filler to poly(bis(2-methoxyethoxy)phosphazene) was 0.3-0.5:1.

[0024] The mixture was stirred and reacted for 1-3 hours at a temperature of 90-100℃ and a pressure of 3-6MPa, and then dried to obtain a halogen-free composite lithium battery solid fire extinguishing agent. The inorganic filler included nano-magnesium hydroxide with a particle size of 50-100nm.

[0025] In this invention, poly(bis(2-methoxyethoxy)phosphazene) containing nitrogen- and phosphorus-synergistic flame-retardant groups and inorganic fillers including nano-magnesium hydroxide are coupled together using vinyltriethoxysilane. When the halogen-free composite lithium battery solid fire extinguishing agent prepared using this method extinguishes a fire, the phosphonic acid derivatives produced by the thermal decomposition of the bis(2-methoxyethoxy)phosphazene groups react with the magnesium oxide produced by the thermal decomposition of magnesium hydroxide to form solid magnesium salts. These solid magnesium salts isolate heat transfer and oxygen, thereby further enhancing the fire extinguishing effect. Simultaneously, the phosphorus-containing groups in the poly(bis(2-methoxyethoxy)phosphazene) can absorb the combustion process... The heat released during combustion lowers the temperature of the combustion zone and slows down the combustion rate. The nitrogen-containing groups in poly(bis(2-methoxyethoxy)phosphazene) absorb a large amount of heat during decomposition, further reducing the temperature of the combustion zone and slowing down the combustion rate, thus enhancing the fire extinguishing effect. Magnesium hydroxide also absorbs a large amount of heat during thermal decomposition, further enhancing the fire extinguishing effect. Furthermore, by coupling poly(bis(2-methoxyethoxy)phosphazene) containing nitrogen and phosphorus synergistic flame-retardant groups with inorganic fillers including nano-magnesium hydroxide using vinyltriethoxysilane, the agglomeration of nano-magnesium hydroxide is avoided, further improving the fire extinguishing effect.

[0026] In some embodiments, the inorganic filler further includes nano-silica with a particle size of 20-100 nm, and the mass ratio of nano-silica to nano-magnesium hydroxide is 1-2:3-4.

[0027] In this invention, nano-silica can enhance the thermal stability of the char layer formed during combustion, thereby further improving the fire extinguishing effect.

[0028] In some embodiments, the reaction solution also includes zinc borate, and the mass ratio of zinc borate to nano-magnesium hydroxide is 3-4:1.

[0029] In this invention, zinc borate can form an inorganic ceramic-like carbonized layer with magnesium oxide, a thermal decomposition product of nano-magnesium hydroxide, during combustion, thereby blocking the transfer of heat and oxygen and further improving the fire extinguishing effect.

[0030] In some embodiments, the present invention also provides a halogen-free composite lithium battery solid fire extinguishing agent prepared according to the preparation method described above.

[0031] 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.

[0032] Example 1

[0033] A method for preparing a halogen-free composite lithium battery solid fire extinguishing agent, the specific steps of which are as follows:

[0034] S1. Add vinyltriethoxysilane to anhydrous ethanol to obtain a mixture, wherein the mass ratio of anhydrous ethanol to vinyltriethoxysilane is 100:10;

[0035] S2. Add poly(bis(2-methoxyethoxy)phosphazene) (commercially available) and 100 nm nano-magnesium hydroxide to the mixture to obtain a reaction solution. The mass ratio of vinyltriethoxysilane to nano-magnesium hydroxide is 0.02:1, and the mass ratio of nano-magnesium hydroxide to poly(bis(2-methoxyethoxy)phosphazene) is 0.3:1.

[0036] S3. The mixture was stirred and reacted at 90℃ and 6MPa for 3 hours, and then dried at 75℃ for 3 minutes to obtain a halogen-free composite lithium battery solid fire extinguishing agent.

[0037] Example 2

[0038] A method for preparing a halogen-free composite lithium battery solid fire extinguishing agent, the specific steps of which are as follows:

[0039] S1. Add vinyltriethoxysilane to anhydrous ethanol to obtain a mixture, wherein the mass ratio of anhydrous ethanol to vinyltriethoxysilane is 100:5;

[0040] S2. Add poly(bis(2-methoxyethoxy)phosphazene) and 50 nm nano-magnesium hydroxide to the mixture to obtain a reaction solution. The mass ratio of vinyltriethoxysilane to nano-magnesium hydroxide is 0.01:1, and the mass ratio of nano-magnesium hydroxide to poly(bis(2-methoxyethoxy)phosphazene) is 0.5:1.

[0041] S3. Stir the reaction at 100℃ and 3MPa for 1 hour, and dry at 65℃ for 5 minutes to obtain a halogen-free composite lithium battery solid fire extinguishing agent.

[0042] Example 3

[0043] A method for preparing a halogen-free composite lithium battery solid fire extinguishing agent, the specific steps of which are as follows:

[0044] S1. Add vinyltriethoxysilane to anhydrous ethanol to obtain a mixture, wherein the mass ratio of anhydrous ethanol to vinyltriethoxysilane is 100:7;

[0045] S2. Add poly(bis(2-methoxyethoxy)phosphazene) and 60 nm nano-magnesium hydroxide to the mixture to obtain a reaction solution. The mass ratio of vinyltriethoxysilane to nano-magnesium hydroxide is 0.015:1, and the mass ratio of nano-magnesium hydroxide to poly(bis(2-methoxyethoxy)phosphazene) is 0.6:1.

[0046] S3. The mixture was stirred and reacted at 96℃ and 5MPa for 2 hours, and then dried at 72℃ for 4 minutes to obtain a halogen-free composite lithium battery solid fire extinguishing agent.

[0047] Example 4

[0048] The difference between this embodiment and embodiment 3 is that:

[0049] S2. Add poly(bis(2-methoxyethoxy)phosphazene) and inorganic filler (composed of nano-magnesium hydroxide with a particle size of 60 nm and nano-silica with a particle size of 50 nm in a mass ratio of 3.6:1) to the mixture to obtain a reaction solution. The mass ratio of vinyltriethoxysilane to inorganic filler is 0.015:1, and the mass ratio of inorganic filler to poly(bis(2-methoxyethoxy)phosphazene) is 0.6:1.

[0050] The difference between this embodiment and Embodiment 3 is that the inorganic filler is composed of nano-magnesium hydroxide with a particle size of 60nm and nano-silica with a particle size of 50nm in a mass ratio of 3.6:1.

[0051] Example 5

[0052] The difference between this embodiment and embodiment 3 is that:

[0053] S2. Add poly(bis(2-methoxyethoxy)phosphazene) and inorganic filler (composed of nano-magnesium hydroxide with a particle size of 60 nm and nano-silica with a particle size of 90 nm in a mass ratio of 4:1.2) to the mixture to obtain a reaction solution. The mass ratio of vinyltriethoxysilane to inorganic filler is 0.015:1, and the mass ratio of inorganic filler to poly(bis(2-methoxyethoxy)phosphazene) is 0.6:1.

[0054] The difference between this embodiment and Embodiment 3 is that the inorganic filler is composed of nano-magnesium hydroxide with a particle size of 60nm and nano-silica with a particle size of 90nm in a mass ratio of 4:1.2.

[0055] Example 6

[0056] The difference between this embodiment and embodiment 3 is that:

[0057] S2. Add poly(bis(2-methoxyethoxy)phosphazene), nano-magnesium hydroxide (particle size 60 nm) and zinc borate to the mixture to obtain a reaction solution. The mass ratio of vinyltriethoxysilane to nano-magnesium hydroxide is 0.015:1, the mass ratio of nano-magnesium hydroxide to poly(bis(2-methoxyethoxy)phosphazene) is 0.6:1, and the mass ratio of zinc borate to nano-magnesium hydroxide is 3:1.

[0058] The difference between this embodiment and Example 3 is that the reaction solution also includes zinc borate, and the mass ratio of zinc borate to nano magnesium hydroxide is 3:1.

[0059] Example 7

[0060] The difference between this embodiment and embodiment 3 is that:

[0061] S2. Add poly(bis(2-methoxyethoxy)phosphazene), nano-magnesium hydroxide (particle size 60 nm) and zinc borate to the mixture to obtain a reaction solution. The mass ratio of vinyltriethoxysilane to nano-magnesium hydroxide is 0.015:1, the mass ratio of nano-magnesium hydroxide to poly(bis(2-methoxyethoxy)phosphazene) is 0.6:1, and the mass ratio of zinc borate to nano-magnesium hydroxide is 4:1.

[0062] The difference between this embodiment and Example 3 is that the reaction solution also includes zinc borate, and the mass ratio of zinc borate to nano magnesium hydroxide is 4:1.

[0063] Comparative Example 1

[0064] Except for the following conditions, the halogen-free composite lithium battery solid fire extinguishing agent was prepared in the same manner as in Example 1:

[0065] S1. Add vinyltriethoxysilane to anhydrous ethanol to obtain a mixture, wherein the mass ratio of anhydrous ethanol to vinyltriethoxysilane is 100:7;

[0066] S2. Add 60 nm nano-sized magnesium hydroxide to the mixture to obtain a reaction solution. The mass ratio of vinyltriethoxysilane to nano-sized magnesium hydroxide is 0.015:1.

[0067] S3. The mixture was stirred and reacted at 96℃ and 5MPa for 2 hours, and then dried at 72℃ for 4 minutes to obtain a halogen-free composite lithium battery solid fire extinguishing agent.

[0068] The difference between this comparative example and Example 1 is that the reaction solution does not contain poly(bis(2-methoxyethoxy)phosphazene).

[0069] Performance testing

[0070] Fire extinguishing simulation tests were conducted on the halogen-free composite lithium battery fire extinguishing agents of Examples 1-7 and Comparative Example 1 respectively: the fire-prone parts of the lithium battery of the electric vehicle were sprayed, specifically using 3 3.7V batteries, the spraying distance was no more than 700m, the package weight was 1kg, the maximum diameter of the initial flame was 600mm, whether it reignited was observed, and the fire extinguishing time was recorded. The results are shown in Table 1.

[0071] Table 1 Test Results

[0072] Group Firefighting time, s Whether it reignites Example 1 12 no Example 2 16 no Example 3 13 no Example 4 8 no Example 5 9 no Example 6 7 no Example 7 8 no Comparative Example 1 31 yes

[0073] As shown in Table 1, the extinguishing time of Example 1 is significantly shortened compared to Comparative Example 1. This indicates that in this invention, when the halogen-free composite lithium battery solid fire extinguishing agent prepared by coupling poly(2-methoxyethoxy)phosphazene containing nitrogen and phosphorus synergistic flame-retardant groups with inorganic fillers including nano-magnesium hydroxide using vinyltriethoxysilane coupling method, the phosphonic acid derivatives produced by the thermal decomposition of the 2-methoxyethoxy)phosphazene groups react with the magnesium oxide produced by the thermal decomposition of magnesium hydroxide to form solid magnesium salts. These solid magnesium salts isolate heat transfer and oxygen, thereby further improving the fire extinguishing effect. At the same time, the phosphorus-containing groups in poly(2-methoxyethoxy)phosphazene can absorb the heat released during combustion, reduce the temperature of the combustion zone, and slow down the combustion rate. The nitrogen-containing groups in poly(2-methoxyethoxy)phosphazene absorb a large amount of heat during decomposition, reducing the temperature of the combustion zone and slowing down the combustion rate, thereby further improving the fire extinguishing effect.

[0074] As shown in Table 1, compared with Example 3 (where the inorganic filler is nano-magnesium hydroxide), the extinguishing time of Examples 4 (where the inorganic filler is composed of nano-magnesium hydroxide with a particle size of 60 nm and nano-silica with a particle size of 50 nm in a mass ratio of 3.6:1) and 5 (where the inorganic filler is composed of nano-magnesium hydroxide with a particle size of 60 nm and nano-silica with a particle size of 90 nm in a mass ratio of 4:1.2) is significantly shortened. This indicates that nano-silica can enhance the thermal stability of the char layer formed during combustion, thereby further improving the extinguishing effect.

[0075] As shown in Table 1, compared with Example 3 (which did not contain zinc borate), the extinguishing time of Examples 6 (which also contained zinc borate, with a mass ratio of zinc borate to nano-magnesium hydroxide of 3:1) and 7 (which also contained zinc borate, with a mass ratio of zinc borate to nano-magnesium hydroxide of 4:1) was significantly shortened. This indicates that zinc borate can form an inorganic ceramic-like carbonized layer with magnesium oxide, a thermal decomposition product of nano-magnesium hydroxide, during combustion, thereby blocking heat transfer and oxygen, and further improving the extinguishing effect.

[0076] 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 method for preparing a halogen-free composite lithium battery solid fire extinguishing agent, characterized in that, include: Vinyltriethoxysilane was added to ethanol to obtain a mixture. Poly(bis(2-methoxyethoxy)phosphazene) and inorganic filler were added to the mixture to obtain a reaction solution. The mixture was stirred and dried to obtain the halogen-free composite lithium battery solid fire extinguishing agent. The inorganic filler included nano-magnesium hydroxide.

2. The preparation method according to claim 1, characterized in that, The stirring reaction is carried out at a temperature of 90-100℃, a pressure of 3-6MPa, and a duration of 1-3h.

3. The preparation method according to claim 1, characterized in that, The particle size of the nano-magnesium hydroxide is 50-100 nm.

4. The preparation method according to claim 1, characterized in that, The mass ratio of the vinyltriethoxysilane to the inorganic filler is 0.01-0.02:1; And / or, the mass ratio of the inorganic filler to poly(bis(2-methoxyethoxy)phosphazene) is 0.3-0.5:

1.

5. The preparation method according to claim 1, characterized in that, The inorganic filler also includes nano-silica.

6. The preparation method according to claim 5, characterized in that, The particle size of the nano-silica is 20-100 nm.

7. The preparation method according to claim 5, characterized in that, The mass ratio of nano-silica to nano-magnesium hydroxide is 1-2:3-4.

8. The preparation method according to claim 1, characterized in that, The reaction solution also includes zinc borate.

9. The preparation method according to claim 8, characterized in that, The mass ratio of zinc borate to nano-magnesium hydroxide is 3-4:

1.

10. A halogen-free composite lithium battery solid fire extinguishing agent prepared by the preparation method according to any one of claims 1-9.