Environment-friendly and non-toxic fire extinguishing agent and preparation method thereof

Abstract

This invention provides an environmentally friendly and non-toxic fire extinguishing agent and its preparation method, relating to the field of fire extinguishing technology. The environmentally friendly and non-toxic fire extinguishing agent includes a fire extinguishing material that decomposes and releases substances with fire extinguishing properties during heating, and a heat-sensitive controlled-release layer. The fire extinguishing material is composed of the following components by weight: 60-70 parts of nano-sized sodium bicarbonate and 1.5-2.5 parts of silica aerogel particles. The heat-sensitive controlled-release layer is composed of modified natural sodium-based montmorillonite and palmitate. In the early stages of lithium battery thermal runaway, when local temperatures rise to 50-90°C, ThermoCap-SB can actively trigger and suppress the chain reaction before the flames ignite, thus extinguishing the fire and preventing it from escalating. The components are non-toxic and have a resistivity >10. 12 It is Ω·cm and pH neutral, and can be used to extinguish fires involving live equipment. It does not damage the BMS circuit board, does not cause secondary short circuit risks, and does not require strong acid neutralization after extinguishing the fire, which greatly reduces operation and maintenance costs.

Description

Technical Field

[0001] This invention relates to the field of fire extinguishing technology, specifically to an environmentally friendly and non-toxic fire extinguishing agent and its preparation method. Background Technology

[0002] With the rapid development of new energy vehicles, the number of lithium batteries is increasing. The normal operating temperature of lithium batteries is 15°C to 35°C. Within this range, the electrochemical reaction kinetics are optimal, the charge and discharge efficiency is high, the internal resistance is stable, and the cycle life is the longest. When the temperature is >45°C, the risk of thermal runaway increases sharply. Generally, the warning threshold for thermal runaway is ≥55°C, which is accompanied by a sudden drop in voltage and the release of CO gas, which can easily lead to fire. Fires caused by lithium batteries are not easy to extinguish. When a lithium battery catches fire, it is generally extinguished by BC dry powder. However, C dry powder relies solely on NaHCO3 to decompose CO2, but it is prone to agglomeration and failure at high temperatures, resulting in poor effectiveness. Moreover, it needs to be triggered at >150°C. It cannot be effective in the early stage when the local temperature rises to 50–90°C (SEI film decomposition, electrolyte vaporization), and cannot avoid losses in the early stage. Summary of the Invention

[0003] (a) Technical problems to be solved To address the shortcomings of existing technologies, this invention provides an environmentally friendly and non-toxic fire extinguishing agent and its preparation method, which can effectively extinguish lithium battery fires and is triggered in the early stages of lithium battery combustion, thereby effectively preventing the fire from spreading and reducing human losses.

[0004] (II) Technical Solution To achieve the above objectives, the present invention provides the following technical solution: an environmentally friendly and non-toxic fire extinguishing agent, comprising a fire extinguishing material that decomposes and releases a substance with fire extinguishing properties during heating, and a heat-sensitive controlled-release layer. The fire extinguishing material is composed of the following components by weight: 60-70 parts of nano-sized sodium bicarbonate and 1.5-2.5 parts of silica aerogel particles. The heat-sensitive controlled-release layer is composed of modified natural sodium-based montmorillonite and palmitate.

[0005] Preferably, the mass ratio of modified natural sodium-based montmorillonite to palmitate in the thermosensitive controlled-release layer is 1:1.3.

[0006] Preferably, the interlayer spacing of the modified natural sodium-based montmorillonite is 2 nm.

[0007] A method for preparing an environmentally friendly and non-toxic fire extinguishing agent includes the following preparation steps: (1) Dehydrate 99.9% nano NaHCO3 for 2 hours to avoid storage clumping that would affect dispersibility; (2) Preparation of modified natural sodium-based montmorillonite; (3) Heat food-grade palmitate to 58°C to melt, add 0.3wt% Span-80 as an emulsifying agent, and stir until clear; (4) Prepared modified natural sodium-based montmorillonite was dispersed in molten palmitate, SiO2 aerogel was added, and O / O type microemulsion was formed by high-speed shearing. NaHCO3 was ultrasonically dispersed in Tris-HCl buffer at pH=8.5 to form an aqueous phase. (5) In a constant temperature water bath at 55±1℃, the aqueous phase was added dropwise to the oil phase at a rate of 0.5 mL / min and stirred continuously for 2 h; then the temperature was raised to 62℃ and kept at that temperature for 1 h to allow the palmitate phase change to dynamically coat the CTAB-MMT sheets: (6) Cool to room temperature, add anhydrous ethanol to break the emulsion, centrifuge and discard the clear upper layer, wash the residue three times with pH=7.0 PBS buffer, and then freeze dry at -50℃ for 48h to obtain a white fluffy powder. (7) Store in a nitrogen-filled, sealed aluminum foil bag.

[0008] Preferably, the preparation of modified natural sodium-based montmorillonite includes the following specific preparation steps: S1. Natural sodium montmorillonite was ion-exchanged three times with 1 mol / L NaCl solution, then stirred in an 80℃ water bath for 2 hours, and centrifuged and washed until no Cl was found. - purified Na was obtained by vacuum drying at 60℃. + -MMT; S2. Put Na + -MMT was dispersed in deionized water and sonicated for 30 min. Then, CTAB aqueous solution was slowly added dropwise, and the mixture was stirred at a constant temperature of 60℃ for 24 h. After natural cooling, the mixture was centrifuged to obtain the precipitate CTAB-MMT, which was then washed three times with a 3:1 mixture of ethanol and water. S3. The precipitate CTAB-MMT was dried in a vacuum drying oven at 60℃ for 12 hours to obtain white powder CTAB-MMT; the d001 peak position was measured by X-ray diffraction after grinding CTAB-MMT.

[0009] Preferably, the parameters for high-speed shearing in step (4) are 12,000 rpm and 10 min, the parameters for stirring in step (5) are 400 rpm, and the parameters for centrifugation in step (6) are 8,000 rpm and 15 min.

[0010] Preferably, the Na + -MMT is dispersed in deionized water at a ratio of 5 wt%.

[0011] CTAB is an abbreviation for hexadecyltrimethylammonium bromide, and MMT is an abbreviation for montmorillonite.

[0012] Working principle: When heated to ≥50℃, it absorbs heat and begins to decompose and release CO2, reducing the oxygen content in the air and achieving the purpose of fire extinguishing; palmitate undergoes a solid-liquid phase transition at 52–58℃, instantly "expanding" the montmorillonite layers and precisely triggering the exposure and decomposition of NaHCO3; silica aerogel particles have a specific surface area >800m². 2 / g, absorbs flame heat and blocks radiation, and forms a fluffy heat-insulating layer after gas release to cover the surface of the burning material and inhibit reignition.

[0013] (III) Beneficial Effects This invention provides an environmentally friendly and non-toxic fire extinguishing agent and its preparation method. It has the following beneficial effects: 1. When the local temperature rises to 50–90°C in the early stage of thermal runaway of lithium battery, ThermoCap-SB can actively trigger and suppress the chain reaction before the flames erupt, thus extinguishing the fire and preventing it from growing larger.

[0014] 2. SiO2 aerogel particles adsorb heat and form an inert thermal insulation layer, blocking the thermal feedback loop and preventing the cascading thermal runaway of adjacent cells.

[0015] 3. Montmorillonite-sodium carbonate residue forms a dense passivation film on the electrode surface, inhibiting the continuous generation of substances such as CO and C2H4.

[0016] 4. The components are non-toxic and the resistivity is >10. 12 It is Ω·cm and pH neutral, and can be used to extinguish fires involving live equipment. It does not damage the BMS circuit board, does not cause secondary short circuit risks, and does not require strong acid neutralization after extinguishing the fire, which greatly reduces operation and maintenance costs. Detailed Implementation

[0017] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0018] Example 1: This invention provides an environmentally friendly and non-toxic fire extinguishing agent. The fire extinguishing agent includes a fire extinguishing material that can decompose and release substances with fire extinguishing properties during heating, and a heat-sensitive controlled-release layer. The fire extinguishing material is composed of the following components by weight: 60-70 parts of nano-sized sodium bicarbonate and 1.5-2.5 parts of silica aerogel particles. The heat-sensitive controlled-release layer is composed of modified natural sodium-based montmorillonite and palmitate.

[0019] • All components are natural minerals or biomass derivatives, and the degradation product is Na. + HCO3- SiO2 and CO2 have no cumulative toxicity to soil / water. 50 With a particle size of 8.3 μm, which is far above the alveolar deposition threshold of <4 μm, 99.2% of the particles settled in the upper respiratory tract and were cleared by cilia, posing no risk of pneumoconiosis.

[0020] D 50 This refers to the particle size at which 50% of all particles are cumulatively distributed according to aerodynamic behavior. In other words, 50% of the particles are smaller than 8.3 μm, and 50% of the particles are larger than 8.3 μm.

[0021] Montmorillonite is a 2:1 type layered silicate. Its structural unit consists of two layers of SiO4 tetrahedra sandwiching a layer of AlO2(OH)4 octahedra. The layers are held together by weak electrostatic attraction, and the original interlayer spacing is only ~1.2 nm.

[0022] The modified natural sodium-based montmorillonite and palmitate in the thermosensitive controlled-release layer have a mass ratio of 1:1.3.

[0023] The interlayer spacing of the modified natural sodium-based montmorillonite is 2 nm.

[0024] A method for preparing an environmentally friendly and non-toxic fire extinguishing agent includes the following preparation steps: (1) Dehydrate 99.9% nano NaHCO3 for 2 hours to avoid storage clumping that would affect dispersibility; (2) Preparation of modified natural sodium-based montmorillonite; (3) Heat food-grade palmitate to 58°C to melt, add 0.3wt% Span-80 as an emulsifying agent, and stir until clear; (4) Prepared modified natural sodium-based montmorillonite was dispersed in molten palmitate, SiO2 aerogel was added, and O / O type microemulsion was formed by high-speed shearing. NaHCO3 was ultrasonically dispersed in Tris-HCl buffer at pH=8.5 to form an aqueous phase. (5) In a constant temperature water bath at 55±1℃, the aqueous phase was added dropwise to the oil phase at a rate of 0.5 mL / min and stirred continuously for 2 h; then the temperature was raised to 62℃ and kept at that temperature for 1 h to allow the palmitate phase change to dynamically coat the CTAB-MMT sheets: (6) Cool to room temperature, add anhydrous ethanol to break the emulsion, centrifuge and discard the clear upper layer, wash the residue three times with pH=7.0 PBS buffer, and then freeze dry at -50℃ for 48h to obtain a white fluffy powder. (7) Store in a nitrogen-filled, sealed aluminum foil bag.

[0025] The preparation of modified natural sodium-based montmorillonite includes the following specific steps: S1. Natural sodium montmorillonite was ion-exchanged three times with 1 mol / L NaCl solution, then stirred in an 80℃ water bath for 2 hours, and centrifuged and washed until no Cl was found. - purified Na was obtained by vacuum drying at 60℃. + -MMT; S2. Put Na + -MMT was dispersed in deionized water and sonicated for 30 min. Then, CTAB aqueous solution was slowly added dropwise, and the mixture was stirred at a constant temperature of 60℃ for 24 h. After natural cooling, the mixture was centrifuged to obtain the precipitate CTAB-MMT, which was then washed three times with a 3:1 mixture of ethanol and water. S3. The precipitate CTAB-MMT was dried in a vacuum drying oven at 60℃ for 12 hours to obtain white powder CTAB-MMT; the d001 peak position was measured by X-ray diffraction after grinding CTAB-MMT.

[0026] CTAB dissociates into CTA in water. + and Br - CTA + Displacement of interlayer Na by strong electrostatic interaction + CTA becomes a new interlayer counterion. + The hexadecyl long chain exhibits strong hydrophobicity; within the confined space between layers, to reduce the system's free energy, the two CTAs... + The chains are laid out in an antiparallel manner on the surface of the laminate, with the methyl end facing the center of the interlayer and the quaternary ammonium head group anchored on the silicon-oxygen surface. After CTAB intercalation, the originally hydrophilic interlayer becomes a hydrophobic region, which significantly reduces the tendency of water molecules to enter and inhibits the interlayer collapse. At the same time, it improves the compatibility of MMT in nonpolar matrices.

[0027] In step (4), the high-speed shearing parameters are 12,000 rpm and 10 min; in step (5), the stirring parameters are 400 rpm; and in step (6), the centrifugation parameters are 8,000 rpm and 15 min.

[0028] Na + -MMT is dispersed in deionized water at a ratio of 5 wt%.

[0029] Example 2: An environmentally friendly and non-toxic fire extinguishing agent includes a fire extinguishing material that decomposes and releases substances with fire extinguishing properties during heating, and a heat-sensitive controlled-release layer. The fire extinguishing material is composed of the following components by weight: 60 parts of nano-sized sodium bicarbonate and 1.5 parts of silica aerogel particles.

[0030] Example 3: An environmentally friendly and non-toxic fire extinguishing agent includes a fire extinguishing material that decomposes and releases substances with fire extinguishing properties during heating, and a heat-sensitive controlled-release layer. The fire extinguishing material is composed of the following components by weight: 65 parts of nano-sized sodium bicarbonate and 2 parts of silica aerogel particles.

[0031] Example 4: An environmentally friendly and non-toxic fire extinguishing agent includes a fire extinguishing material that decomposes and releases substances with fire extinguishing properties during heating, and a heat-sensitive controlled-release layer. The fire extinguishing material is composed of the following components by weight: 70 parts of nano-sized sodium bicarbonate and 2.5 parts of silica aerogel particles.

[0032] Table 1 Performance Comparison Table ; As can be seen from the table above, the fire extinguishing material in Example 3, composed of 65 parts of nano-sized sodium bicarbonate and 2 parts of silica aerogel particles, has the best effect.

[0033] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. An environmentally friendly and non-toxic fire extinguishing agent, characterized in that: The fire extinguishing agent includes a fire extinguishing material that can decompose and release substances with fire extinguishing properties during heating, and a heat-sensitive controlled-release layer. The fire extinguishing material is composed of the following components by weight: 60-70 parts of nano-sized sodium bicarbonate and 1.5-2.5 parts of silica aerogel particles. The heat-sensitive controlled-release layer is composed of modified natural sodium-based montmorillonite and palmitate.

2. The environmentally friendly and non-toxic fire extinguishing agent according to claim 1, characterized in that: The modified natural sodium-based montmorillonite and palmitate in the thermosensitive controlled-release layer have a mass ratio of 1:1.

3.

3. The environmentally friendly and non-toxic fire extinguishing agent according to claim 1, characterized in that: The interlayer spacing of the modified natural sodium-based montmorillonite is 2 nm.

4. The preparation method of the environmentally friendly and non-toxic fire extinguishing agent according to any one of claims 1-3, characterized in that: The preparation steps include the following: (1) Dehydrate 99.9% nano NaHCO3 for 2 hours to avoid storage clumping that would affect dispersibility; (2) Preparation of modified natural sodium-based montmorillonite; (3) Heat food-grade palmitate to 58°C to melt, add 0.3wt% Span-80 as an emulsifying agent, and stir until clear; (4) Prepared modified natural sodium-based montmorillonite was dispersed in molten palmitate, SiO2 aerogel was added, and O / O type microemulsion was formed by high-speed shearing. NaHCO3 was ultrasonically dispersed in Tris-HCl buffer at pH=8.5 to form an aqueous phase. (5) In a constant temperature water bath at 55±1℃, the aqueous phase was added dropwise to the oil phase at a rate of 0.5 mL / min and stirred continuously for 2 h; then the temperature was raised to 62℃ and kept at that temperature for 1 h to allow the palmitate phase change to dynamically coat the CTAB-MMT sheets: (6) Cool to room temperature, add anhydrous ethanol to break the emulsion, centrifuge and discard the clear upper layer, wash the residue three times with pH=7.0 PBS buffer, and then freeze dry at -50℃ for 48h to obtain a white fluffy powder. (7) Store in a nitrogen-filled, sealed aluminum foil bag.

5. The method for preparing an environmentally friendly and non-toxic fire extinguishing agent according to claim 4, characterized in that: The preparation of modified natural sodium-based montmorillonite includes the following specific preparation steps: S1. Natural sodium montmorillonite was ion-exchanged three times with 1 mol / L NaCl solution, then stirred in an 80℃ water bath for 2 hours, and centrifuged and washed until no Cl was found. - purified Na was obtained by vacuum drying at 60℃. + -MMT; S2. Put Na + -MMT was dispersed in deionized water and sonicated for 30 min. Then, CTAB aqueous solution was slowly added dropwise, and the mixture was stirred at a constant temperature of 60℃ for 24 h. After natural cooling, the mixture was centrifuged to obtain the precipitate CTAB-MMT, which was then washed three times with a 3:1 mixture of ethanol and water. S3. The precipitate CTAB-MMT was dried in a vacuum drying oven at 60℃ for 12 hours to obtain white powder CTAB-MMT; the d001 peak position was measured by X-ray diffraction after grinding CTAB-MMT.

6. The method for preparing an environmentally friendly and non-toxic fire extinguishing agent according to claim 4, characterized in that: In step (4), the high-speed shearing parameters are 12,000 rpm and 10 min; in step (5), the stirring parameters are 400 rpm; and in step (6), the centrifugation parameters are 8,000 rpm and 15 min.

7. The method for preparing an environmentally friendly and non-toxic fire extinguishing agent according to claim 5, characterized in that: The Na + -MMT is dispersed in deionized water at a ratio of 5 wt%.