CN115671641B - A high vaporization heat porous fire extinguishing medium used in electrochemical energy storage systems and its preparation method - Google Patents

Abstract

The present invention relates to the field of fire extinguishing media. In order to solve the problem in the existing technology that the fire extinguishing agent of the electrochemical energy storage system is slow to cool down and cannot continue to cool down, a high vaporization heat porous fire extinguishing device applied to the electrochemical energy storage system is disclosed. Medium, the high vaporization heat porous fire extinguishing medium is a liquid sol containing nanoporous material and perfluorohexanone, and the nanoporous material is a metal-organic framework material. The porous fire-extinguishing medium has high vaporization heat and fast vaporization speed, which can effectively overcome the shortcomings of perfluorohexanone's insufficient cooling performance. It can quickly extinguish open flames and continuously cool down lithium-ion battery fires, thereby effectively suppressing its re-ignition and lasting for a long time. save. The invention also provides a method for preparing a high vaporization heat porous fire extinguishing medium applied to an electrochemical energy storage system. The method has a simple preparation process and can regulate product performance.

Description

A high vaporization heat porous fire extinguishing medium used in electrochemical energy storage systems and its preparation Preparation method

Technical field

The present invention relates to the field of fire extinguishing media, and in particular to a high vaporization heat porous fire extinguishing medium used in electrochemical energy storage systems and a preparation method thereof.

Background technique

Energy storage can effectively ensure the safe and stable operation of high-proportion new energy power systems and improve the level of new energy utilization. It is an important technology and basic equipment to support new power systems. It is important for promoting green energy transformation, responding to extreme events, ensuring energy security, and promoting high energy levels. It is of great significance to develop quality and support the achievement of climate change goals. Electrochemical energy storage has the characteristics of rapid response, two-way regulation, and small dispersion. In recent years, with the continuous breakthroughs in core technologies and the gradual reduction of construction costs, it has shown a trend of accelerated development. Lithium-ion batteries are an important part of the field of electrochemical energy storage.

Currently, lithium-ion batteries are at risk of thermal runaway under thermal, electrical and mechanical abuse conditions. Especially for energy storage systems, thermal runaway of a single battery will develop into a large-scale explosion, resulting in huge casualties and property losses. Different from conventional fires, lithium-ion battery fires are endogenous, forming a comprehensive fire that is a mixture of gas fires, liquid fires and solid fires during the battery combustion process. Currently, the fire extinguishing agent equipped in existing energy storage power stations is heptafluoropropane. For example, the announcement number CN108744344A| published in Chinese patent documents is "a fire protection system for lithium power batteries". The fire extinguishing medium is heptafluoropropane gas or fluorinated ketone. gas. Practice has shown that heptafluoropropane is based on the mechanism of physical dilution to isolate oxygen or cut off the combustion chain. It can only extinguish open flames. It does not have the function of rapid and continuous cooling. It cannot effectively block the thermal runaway reaction of the battery. It is prone to re-ignition and is difficult to completely extinguish lithium-ion batteries. fire. As a new generation fire extinguishing agent, perfluorohexanone has a low boiling point. Although it can inhibit the re-ignition of lithium-ion battery fires to a certain extent, perfluorohexanone's vaporization rate is slow, resulting in its cooling ability being limited and unable to exert its own effect. Insulation, environmental friendliness and other advantages. Therefore, it is urgent to develop fire extinguishing agents with high vaporization heat for lithium-ion batteries, especially large-scale lithium-ion battery energy storage systems.

Contents of the invention

In order to overcome the problem in the prior art that the fire extinguishing agent of the electrochemical energy storage system has a slow cooling speed and cannot continue to cool down, the present invention provides a high vaporization heat porous fire extinguishing medium for use in the electrochemical energy storage system. The porous fire extinguishing medium The medium has good fluidity, fast vaporization speed, and high latent heat of vaporization, which can quickly reduce the temperature of the ignition point of the electrochemical energy storage system. The invention also provides a method for preparing a high vaporization heat porous fire extinguishing medium applied to the electrochemical energy storage system. , this method has a simple preparation process and can control product performance.

In order to achieve the above objects, the present invention adopts the following technical solutions:

A high vaporization heat porous fire extinguishing medium used in electrochemical energy storage systems. The high vaporization heat porous fire extinguishing medium is a liquid sol containing nanoporous materials and perfluorohexanone.

Perfluorohexanone can vaporize away the heat from the ignition point and isolate oxygen near the ignition point. Perfluorohexanone has good insulation and will not corrode metal, so it will not cause secondary damage to burning electronic components and circuits. The invention is a stable liquid colloid porous fire-extinguishing medium with high vaporization heat formed by dispersing nano-porous materials into perfluorohexanone. The nano-porous materials make the porous fire-extinguishing medium permanently microporous, which reduces the overall density of the porous fire-extinguishing medium and reduces the heat of vaporization. At the same vaporization temperature, the porous fire-extinguishing medium vaporizes faster than pure perfluorohexanone, which can quickly take away more heat, significantly improve the fire-extinguishing effect, and the porous fire-extinguishing medium has good fluidity Easy to spray and covers fire spots.

Preferably, the nanoporous material is a metal-organic framework material.

The metal-organic framework material has a microporous structure and can be combined with perfluorohexanone, so the metal-organic framework material can be stably dispersed in perfluorohexanone to obtain a liquid sol with uniform texture.

Preferably, the particle size of the metal organic framework material is 10-500 nm.

Preferably, the nanoporous material is a zirconium-based metal-organic framework material.

The Zr site in the zirconium-based metal-organic framework material has a specific fluoride ion binding function and has a good binding effect with perfluorohexanone. It can increase the content of nanoporous materials in the porous fire-extinguishing medium while maintaining the fluidity of the porous fire-extinguishing medium. , thereby increasing the vaporization speed of the porous fire-extinguishing medium, and the zirconium-based metal-organic framework material itself also has good insulation, which will not affect the fire-extinguishing application of perfluorohexanone in electrochemical energy storage systems.

More preferably, the nanoporous material is UIO-66-NH ₂ .

In addition to Zr sites, UIO-66-NH ₂ also contains amino groups, which can also specifically bind fluoride ions, further improving the binding effect of nanoporous materials and perfluorohexanone, thereby increasing the content of nanoporous materials in the lyosol, making The density of porous fire extinguishing media is reduced and the cooling ability is improved.

Preferably, the zirconium-based metal-organic framework material is prepared by the following steps: dissolving zirconium salt and organic ligands in a solvent, heating and reacting, and separating and collecting the precipitate after the reaction. The precipitate is the zirconium-based metal-organic framework material.

Preferably, the zirconium salt is zirconium tetrachloride, zirconium oxychloride octahydrate or zirconium propoxide, the organic ligand is terephthalic acid or a monovalent substitution product of terephthalic acid, and the zirconium ions in the zirconium salt are in contact with the organic The molar ratio of ligands is 1: (1-1.5), the heating reaction temperature is 100-120°C, and the reaction time is 24-30h.

More preferably, the monosubstituted product of terephthalic acid is aminoterephthalic acid, nitroterephthalic acid or trimellitic acid.

Preferably, the solvent is N,N-dimethylformamide or a mixed solution of N,N-dimethylformamide and water.

Preferably, the preparation step of the zirconium-based metal organic framework material also includes washing the collected precipitate with N,N-dimethylformamide and methanol, drying it at a temperature of 70-80°C, and repeating the washing for 2-3 times. Second-rate.

The precipitation is washed with N,N-dimethylformamide and methanol to remove impurities in the pores of the nanoporous material and improve the binding effect of zirconium-based metal-organic framework materials and perfluorohexanone.

A method for preparing porous fire-extinguishing media with high vaporization heat applied to electrochemical energy storage systems. The preparation method includes adding nanoporous materials to perfluorohexanone, ultrasonic treatment to obtain a dispersion, and discarding the solids in the dispersion. Porous fire extinguishing media.

Through ultrasonic vibration treatment, the nanoporous material is dispersed into perfluorohexanone, and the precipitate in the dispersion is removed, and the liquid obtained is the porous fire extinguishing medium. Nanoporous materials that are not combined with perfluorohexanone in the dispersion have no effect on the fire extinguishing performance of the porous fire extinguishing medium, but after long-term storage, these free nanoporous materials will form precipitates at the bottom of the porous fire extinguishing medium. When the porous fire extinguishing medium passes through the nozzle When released, the precipitation will block the nozzle, making it difficult for the porous fire-extinguishing medium to be sprayed to the ignition point.

Preferably, the mass volume ratio of the nanoporous material and perfluorohexanone is (1-4) g:10 mL.

When the nanoporous material in the porous fire extinguishing medium does not reach the saturated state, the density of the porous fire extinguishing medium decreases as the content of the nanoporous material increases, so the cooling effect of the porous fire extinguishing medium increases as the content of the nanoporous material increases; when the porous fire extinguishing medium When the medium-nano porous material reaches a saturated state, it has the best cooling effect. At this time, even if the amount of nano-porous material is increased, the nano-porous material cannot combine with perfluorohexanone to form a colloid, but is free in the porous fire-extinguishing medium as a precipitate. , the performance of porous fire extinguishing media can no longer be improved.

Preferably, the ultrasonic treatment time is 10-20 minutes.

Preferably, the process of discarding the solids in the dispersion of the preparation method is to centrifuge the dispersion and then discard the precipitate in the dispersion. The centrifugation speed is 1200-1500r/min, the centrifugation time is 5-15min, and the centrifugation operation is repeated for 5-10 minutes. Second-rate.

Therefore, the present invention has the following beneficial effects: the porous fire extinguishing medium can effectively overcome the defect of insufficient cooling performance of perfluorohexanone, has high vaporization heat, fast vaporization speed, and good insulation, can be used in electrochemical energy storage system fires, and quickly resists fires. Extinguish open flames and continuously cool down, thereby effectively suppressing re-ignition.

Description of the drawings

Figure 1 is the XRD analysis chart of UIO-66- _NH2 prepared in Example 1.

Figure 2 is an SEM image of UIO-66-NH ₂ prepared in Example 1.

Figure 3 is a cooling curve diagram of the porous fire extinguishing medium prepared in Example 1.

Figure 4 is the cooling curve of perfluorohexanone.

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings and specific implementation methods.

Example 1

A high vaporization heat porous fire extinguishing medium used in electrochemical energy storage systems is prepared by the following steps:

(1) Preparation of nanoporous materials: Weigh 0.56g zirconium tetrachloride and dissolve it in 75mL of N,N-dimethylformamide (DMF). After stirring to complete the dissolution, add 0.42g 2-amino- Terephthalic acid, continue stirring to complete dissolution, add the reaction solution into a 100 mL polytetrafluoroethylene reactor, heat it to 120°C in a blast drying oven and react for 24 hours, then naturally cool to room temperature. Centrifuge the product at 10000r/min for 15min to collect the precipitate, and wash the precipitate three times with DMF and methanol respectively to remove impurities in the pores of the material. Finally, dry the obtained precipitate in a vacuum oven at 80°C to obtain the required nanoporous Material UIO-66-NH ₂ ;

(2) Preparation of porous fire-extinguishing medium: Weigh 8g of nanoporous material into a 50mL glass bottle, add 20mL of perfluorohexanone to dissolve, seal the glass bottle with a polytetrafluoroethylene cap, and ultrasonicate for 15 minutes to obtain a dispersion. Transfer to a 50 mL centrifuge tube and perform 5 centrifugation cycles. In each round of centrifugation, the speed is 1500r/min and the centrifugation time is 15min. After each round of centrifugation, the supernatant is decanted and transferred to a new test tube for next step. After one round of centrifugation, the final supernatant is the required porous fire extinguishing medium.

Conduct XRD test and SEM test on the nanoporous material obtained in step (1) of Example 1. The XRD analysis chart of the nanoporous material is shown in Figure 1. The PXRD peak position of the UIO-66-NH ₂ material is consistent with the peak position of the standard card, proving that the UIO-66-NH ₂ prepared in step (1) is the product of the present invention. The required zirconium-based organic framework material containing amino groups. The SEM test results of nanoporous materials are shown in Figure 2. The particle size of the synthesized UIO-66- _NH2 is 20-40nm and has an octahedral structure. The composition and morphology structure test results of the nanoporous material obtained in step (1) all show that the UIO-66-NH ₂ material was successfully synthesized in step (1).

The porous fire extinguishing medium prepared in Example 1 and perfluorohexanone were respectively subjected to a cooling test. The test steps were:

A. Select a cast aluminum heating plate with a heating voltage of 220V and a heating power of 300W, and place it in a semi-enclosed stainless steel container. The size of the heating plate is 100mm long × 100mm wide × 20mm thick. Place a heat insulation pad between the heating plate and the container. layer, the cushion thickness is 2mm;

B. Add 500g of fire extinguishing medium into the bottle equipped with a nozzle, place the nozzle above the center point of the heating plate, and the distance from the heating plate is 50mm; the heating plate has three φ1mm round holes with a depth of 1mm a. b, c, round hole a is set at the center of the heating plate, round hole b is set at the corner of the heating plate 10mm away from the edge, round hole c is set opposite to round hole b with round hole a as the center, and in each round hole Insert thermocouples respectively to collect real-time temperature values;

C. Heat the heating plate and spray the fire-extinguishing medium with a nozzle. The remaining rate of spraying the fire-extinguishing medium is 5%. Record the change curve of the average temperature collected by the three thermocouples.

The temperature change in the cooling test of Example 1 is shown in Figure 3. The temperature of the heating plate rises after continuous heating. When the porous fire extinguishing medium is sprayed, it can be clearly seen that the temperature curve of the heating plate drops rapidly and does not rise. This illustrates the embodiment. 1 The obtained porous fire extinguishing medium has rapid cooling ability and excellent continuous cooling performance. The temperature change when using perfluorohexanone is shown in Figure 4. During the spraying process of perfluorohexanone, the temperature of the heating plate dropped, but the lowest temperature it dropped to was higher than the lowest temperature after the drop in Figure 3. At the same time, the temperature of the heating plate dropped. After the spraying of fluorohexanone, the temperature fluctuation of the heating plate increased, which shows that the continuous cooling performance of perfluorohexanone is worse than that of the porous fire extinguishing medium prepared in Example 1.

Example 2

A high vaporization heat porous fire extinguishing medium used in electrochemical energy storage systems. The difference from Example 1 is that the amount of nanoporous material UIO-66-NH ₂ added in step (2) is 2g.

Example 3

A porous fire-extinguishing medium with high vaporization heat used in electrochemical energy storage systems. The difference from Example 1 is that in step (1), the reaction liquid is heated to 100°C in a blast drying oven and reacted for 36 hours. The size of the obtained nanoporous material UIO-66- _NH2 is 60-80nm.

Example 4

A porous fire extinguishing medium with high vaporization heat used in electrochemical energy storage systems. The difference from Example 1 is that 0.39g terephthalic acid is used to replace 2-amino-terephthalic acid in step (1).

Example 5

A porous fire-extinguishing medium with high vaporization heat used in electrochemical energy storage systems. The difference from Example 1 is that 0.49g of nitroterephthalic acid is used to replace 2-amino-terephthalic acid in step (1).

Example 6

A high vaporization heat porous fire extinguishing medium used in electrochemical energy storage systems is prepared by the following steps:

(1) Preparation of porous fire-extinguishing medium: Weigh 8g MOF-5 (purchased from Ruixi Biotech) into a 50mL glass bottle, add 20mL perfluorohexanone to dissolve, seal the glass bottle with a polytetrafluoroethylene cap, and ultrasonicate for 15 minutes to obtain Dispersion, transfer the dispersion into a 50mL centrifuge tube and perform 5 centrifugation cycles. The speed of centrifugation in each round is 1500r/min and the centrifugation time is 15min. After each round of centrifugation, the supernatant is decanted and transferred to a new tube. The next round of centrifugation is carried out in the test tube, and the final supernatant is the required porous fire-extinguishing medium.

According to "GB/T19466.4 Differential Scanning Calorimetry (DSC) Part 4 Determination of Specific Heat Capacity", "GB/T265-1988 Petroleum Products Kinematic Viscosity Determination Method and Dynamic Viscosity Calculation Method", "GB/T 507 Insulating Oil The performance of perfluorohexanone and the porous fire extinguishing media prepared in Examples 1-5 and Comparative Example 1 was tested using the method described in "Dielectric Strength Determination Method", and the results are shown in the table below.

It can be seen from the data in the above table that compared with perfluorohexanone, the latent heat of vaporization of the present invention is significantly increased, the cooling effect is better, and the fluidity and insulation properties are good, and it is suitable for fire extinguishing in electrochemical energy storage systems.

It can be seen from the density and latent heat of vaporization data in the above table that the nanoporous materials added in Examples 1-6 can reduce the density of the porous fire extinguishing medium, and the density of the porous fire extinguishing medium is negatively related to its latent heat of vaporization. At the same time, it can be seen from the breakdown voltage that nanoporous materials can improve the insulation of porous fire extinguishing media.

In step (2) of Example 2, no precipitation was observed with the naked eye after centrifugation of the dispersion, which indicated that all the added UIO-66-NH ₂ had been combined with perfluorohexanone, but UIO-66-NH ₂ in the porous fire extinguishing medium Not yet saturated, the vaporization heat of the porous fire extinguishing medium obtained in Example 2 is higher than that of Comparative Example 1, but lower than that of Example 1, which shows that UIO-66-NH ₂ can increase the vaporization heat of perfluorohexanone, and the improvement effect is the same as that of porous fire-extinguishing medium. The content of UIO-66-NH ₂ in the fire extinguishing medium is positively correlated.

In Example 3, the particle size of UIO-66- _NH2 obtained is larger than that of Example 1 by adjusting the synthesis conditions. After adding a saturated amount of UIO-66- _NH2 , the latent heat of vaporization of Example 3 is lower than that of Example 1, which shows that It was found that the ability of UIO-66-NH ₂ to increase the latent heat of vaporization is related to the particle size.

Comparing Examples 1, 4, 5 and 6, it can be seen that when UIO-66, UIO-66- _NO2 or MOF-5 is used, the vaporization heat of the porous fire extinguishing medium obtained is lower than that of the perfluorinated fire extinguishing medium combined with UIO-66- _NH2 . Hexanone, this is because UIO-66, UIO-66-NO ₂ and MOF-5 have weaker binding properties with perfluorohexanone than UIO-66-NH ₂ , resulting in UIO-66, UIO- The upper limit of the binding amount of 66-NO ₂ or MOF-5 will be lower than UIO-66-NH ₂ , and the vaporization heat of the porous fire extinguishing medium cannot be maximized.

Claims (7)

1. A high vaporization heat porous fire extinguishing medium used in electrochemical energy storage systems, characterized in that the high vaporization heat porous fire extinguishing medium is a liquid sol containing nanoporous materials and perfluorohexanone; the nanoporous materials It is a zirconium-based metal-organic framework material with a particle size of 10-500nm. 2. A porous fire-extinguishing medium with high vaporization heat used in electrochemical energy storage systems according to claim 1, characterized in that the zirconium-based metal-organic framework material is prepared by the following steps: zirconium salt, organic compound The body is dissolved in the solvent, and then heated for reaction. After the reaction, the precipitate is separated and collected. The precipitate is the zirconium-based metal-organic framework material. 3. A porous fire-extinguishing medium with high vaporization heat applied to electrochemical energy storage systems according to claim 2, characterized in that the zirconium salt is zirconium tetrachloride, zirconium oxychloride octahydrate or zirconium propoxide. , the organic ligand is terephthalic acid or a monovalent substitution product of terephthalic acid, the molar ratio of zirconium ions in the zirconium salt to the organic ligand is 1: (1-1.5), and the temperature of the heating reaction is 100-120°C , the reaction time is 24-30h. 4. A method for preparing a high vaporization heat porous fire extinguishing medium applied to an electrochemical energy storage system according to any one of claims 1 to 3, characterized in that the preparation method includes adding nanoporous materials to the entire In fluorohexanone, a dispersion is obtained by ultrasonic treatment, and the solid in the dispersion is discarded to obtain a porous fire extinguishing medium. 5. A method for preparing a high vaporization heat porous fire extinguishing medium applied to an electrochemical energy storage system according to claim 4, characterized in that the mass volume ratio of the nanoporous material to perfluorohexanone is (1 -4) g: 10mL. 6. A method for preparing a high vaporization heat porous fire extinguishing medium applied to an electrochemical energy storage system according to claim 4 or 5, characterized in that the ultrasonic treatment time is 10-20 minutes. 7. A method for preparing a porous fire-extinguishing medium with high vaporization heat applied to electrochemical energy storage systems according to claim 4 or 5, characterized in that the process of discarding solids in the dispersion of the preparation method is to disperse the After centrifugation, discard the precipitate in the dispersion. The centrifugation speed is 1200-1500r/min, the centrifugation time is 5-15 min, and the centrifugation operation is repeated 5-10 times.