Fire extinguishing additive for lithium batteries and method for preparing the same

Abstract

The application relates to the technical field of lithium ion fire safety preparation, in particular to a fire extinguishing additive for lithium batteries and a preparation method thereof. Raw materials of the fire extinguishing additive include a composite flame retardant, phase change microcapsules, a free radical capturing agent, a surfactant, a dispersion stabilizer and deionized water. The preparation method of the fire extinguishing additive is as follows: the dispersion stabilizer and the composite flame retardant are added into the deionized water, stirred uniformly, the stirring speed is reduced, the surfactant is added, continuous stirring is carried out, the temperature is increased to 40-50 DEG C, the free radical capturing agent is added, finally, the stirring speed is reduced, the phase change microcapsules are added, and the fire extinguishing additive for lithium batteries is obtained after homogenization treatment. The prepared fire extinguishing additive has the advantages of small dosage, fast fire extinguishing speed, high cooling rate and no afterburning phenomenon.

Description

Technical Field

[0001] This application relates to the field of lithium-ion fire safety preparation technology, and more specifically, it relates to a fire extinguishing additive for lithium batteries and a method for preparing the same. Background Technology

[0002] With the widespread application of lithium batteries in electric vehicles, portable electronic devices, and many other fields, lithium battery fires are becoming increasingly common, and the difficulty of extinguishing them is also becoming more and more prominent. The main reason is that lithium batteries burn extremely violently after ignition, with extremely high temperatures, and the thermal runaway propagates extremely rapidly after combustion. What is even more troublesome is that even if the open flame is extinguished, chemical reactions will continue to occur inside the battery, generating flammable gases. At this time, measures must be taken to continue cooling down to prevent reignition.

[0003] Existing lithium battery fire extinguishing agents are mainly divided into dry powder fire extinguishing agents, water-based fire extinguishing agents, and gaseous fire extinguishing agents. While dry powder fire extinguishing agents can quickly extinguish open flames, they cannot lower the internal temperature of the battery, leading to continued thermal runaway reactions, which can easily reignite or even explode. Water-based fire extinguishing agents isolate oxygen and cool the battery through a water film, but their effect on suppressing deep thermal runaway within the lithium battery is insufficient, requiring large and continuous spraying of water, which is difficult to operate, and spraying water may cause secondary short circuits in the battery, posing a safety hazard, especially in high-voltage battery systems. Gaseous fire extinguishing agents are highly efficient and environmentally friendly, but they are costly and have poor cooling capabilities; in open spaces or poorly ventilated environments, the gas concentration is difficult to maintain, affecting the fire extinguishing effect. Based on these shortcomings, this application provides a fire extinguishing additive for lithium batteries and its preparation method to ensure fire safety during the use of lithium batteries. Summary of the Invention

[0004] To address the technical problems mentioned in the background section, this application provides a fire extinguishing additive for lithium batteries and a method for preparing the same.

[0005] In a first aspect, this application provides a fire extinguishing additive for lithium batteries, employing the following technical solution:

[0006] A fire extinguishing additive for lithium batteries comprises the following raw materials in parts by weight: 25-35 parts of composite flame retardant, 10-12 parts of phase change microcapsules, 10-15 parts of free radical scavenger, 3-6 parts of surfactant, 3-5 parts of dispersant stabilizer, and 70-100 parts of deionized water.

[0007] Preferably, the composite flame retardant is composed of trimethyl phosphate, melamine cyanurate and barium metaborate in a mass ratio of 5-8:2-3:1-2.

[0008] Preferably, the free radical scavenger is one or more of 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene, 2,2,6,6-tetramethylpiperidinol, and 4-hydroxy-2,2,6,6-tetramethylpiperidin-1-oxy.

[0009] Preferably, the surfactant is one or more of sodium dodecyl sulfate, fatty alcohol polyoxyethylene ether, and polysorbate.

[0010] Preferably, the dispersant stabilizer is one or more of polyvinylpyrrolidone, sodium polyacrylate, and gum arabic.

[0011] Preferably, the preparation of the phase change microcapsules includes the following preparation steps:

[0012] Step 1: Mix decanoic acid, lauric acid and polyethylene glycol, heat to 80-85℃, melt and blend, add nano-silica and carbon nanotubes, stir at 300-500 rpm for 30-40 minutes to obtain the core material;

[0013] Step 2: Mix hydroxyethyl methacrylate, methacrylamide, glycidyl methacrylate and deionized water, then add potassium persulfate and sodium dodecylbenzene sulfonate. Under nitrogen protection, the reaction temperature is 70-80℃, and the mixture is stirred for 2-3 hours to obtain the shell material prepolymer solution.

[0014] Step 3: Add the core material to the shell material prepolymer solution and shear at 70-80℃ with a shear speed of 5000-8000 rpm for 20-30 minutes. Add N,N'-methylenebisacrylamide and continue the reaction at 70-75℃ for 1-3 hours. Centrifuge, wash, and dry to obtain phase change microcapsules.

[0015] Preferably, in step 1, the mass ratio of decanoic acid, lauric acid, and polyethylene glycol is 4-8:2-4:5-10.

[0016] Preferably, in step 1, the polyethylene glycol is composed of PEG6000 and PEG2000 in a mass ratio of 10-12:3-5.

[0017] Preferably, in step 1, the amounts of nano-silica and carbon nanotubes added are 2-5% and 1-3% of the total mass of decanoic acid, lauric acid, and polyethylene glycol, respectively.

[0018] Preferably, in step 2, the mass ratio of hydroxyethyl methacrylate, methacrylamide, glycidyl methacrylate, and deionized water is 60-80:10-20:20-30:400-500.

[0019] Preferably, in step 2, the amounts of potassium persulfate and sodium dodecylbenzenesulfonate added are 0.5-2% and 1-3% of the total mass of hydroxyethyl methacrylate, methacrylamide, and glycidyl methacrylate, respectively.

[0020] Preferably, the mass ratio of the core material and shell material prepolymer solution in step 3 is 1:2-5.

[0021] Preferably, in step 3, the amount of N,N'-methylenebisacrylamide added is 2-5% of the total mass of hydroxyethyl methacrylate, methacrylamide, and glycidyl methacrylate.

[0022] Secondly, this application also provides a method for preparing a fire extinguishing additive for lithium batteries, employing the following technical solution:

[0023] Add a dispersant stabilizer and a composite flame retardant to deionized water, and stir at 30-40℃ with a stirring speed of 500-600 rpm for 20-30 minutes. Reduce the stirring speed to 100-200 rpm, add a surfactant, and continue stirring for 10-20 minutes. Increase the temperature to 40-50℃, add a free radical scavenger, and stir for 20-40 minutes. Finally, reduce the stirring speed to 50-100 rpm, add phase change microcapsules, and stir for 30-40 minutes. After homogenization, the fire extinguishing additive for lithium batteries is obtained.

[0024] Preferably, the homogenization pressure is 20-30 MPa, and the homogenization is performed 2-3 times.

[0025] In summary, this application has the following beneficial effects:

[0026] This application utilizes phase change microcapsules in the preparation of fire extinguishing additives to efficiently absorb heat, rapidly cool down, inhibit thermal runaway, and prevent reignition. The core material of the phase change microcapsules is composed of decanoic acid, lauric acid, and polyethylene glycol, forming a eutectic mixture with high latent heat of phase change. When the lithium battery experiences thermal runaway and temperature rises, the core material absorbs a large amount of heat through phase change, effectively reducing local temperature and inhibiting rapid temperature rise, thereby preventing the spread of thermal runaway. The phase change microcapsules work synergistically with the chemical flame retardancy of the composite flame retardant and the chain reaction inhibition of the free radical scavenger. By using a blend of PEG6000 and PEG2000, the phase change temperature range of the core material more closely matches the temperature gradient of lithium battery thermal runaway, achieving phased, multi-temperature heat absorption and improving the ability to regulate battery temperature. Furthermore, the longer molecular chain of PEG6000 increases the viscosity and structural strength of the core material, preventing excessive flow or leakage of low-melting-point components after melting, and improving the filling stability of the core material within the capsule. The shorter molecular chain of PEG2000 reduces system viscosity, improves compatibility with decanoic acid and lauric acid, promotes uniform dispersion during melt blending, and avoids potential issues such as excessively high viscosity and poor flowability. It balances the viscosity, melting point, and mechanical strength of the core material, ensuring it maintains sufficient flowability for heat absorption at high temperatures while preventing leakage. The nano-silica and carbon nanotubes added to the core material possess excellent thermal conductivity, accelerating heat transfer from the lithium battery surface to the phase change material and improving heat absorption efficiency. Carbon nanotubes also enhance the structural stability of the core material, preventing capsule rupture caused by volume expansion during phase change. Furthermore, the phase change microcapsules, in conjunction with the dispersing stabilizers and surfactants in the system, can be uniformly dispersed in the aqueous solution, ensuring rapid contact with the battery surface during fire extinguishing and exerting a cooling effect.

[0027] In the preparation of the shell material for phase change microcapsules, this application selects three monomers through complementary functional groups and structural synergy, enabling the shell material to possess high mechanical strength, heat resistance, hydrophilicity, and interfacial compatibility. The flexible segments of hydroxyethyl methacrylate reduce the rigidity of the shell material, preventing shell brittleness at high temperatures; the polar groups and cross-linked structures of methacrylamide and glycidyl methacrylate improve the hardness and heat resistance of the shell material, allowing the microcapsules to maintain structural integrity in the high-temperature environment of lithium battery fires, strengthening the core-shell interface bonding, and preventing core material leakage. Furthermore, the polymer network structure of the shell material not only protects the core material but also forms a lightweight heat-insulating film on the lithium battery surface, blocking oxygen and heat transfer and assisting in flame retardancy. Simultaneously, the phase change microcapsules do not directly react with the composite flame retardant and free radical scavenger, avoiding compatibility issues between components and ensuring the chemical stability of the fire extinguishing additive during storage and use.

[0028] This application utilizes the high-temperature decomposition of trimethyl phosphate to generate phosphorus-containing free radicals, which capture active free radicals in the combustion chain reaction, inhibiting flame propagation. The high-temperature decomposition also generates phosphoric acid and polyphosphoric acid, which promote the dehydration and carbonization of combustibles, forming a dense char layer that isolates heat and oxygen and reduces the release of combustible gases. Melamine cyanurate decomposes at high temperatures to produce non-combustible gases such as NH3 and N2, diluting the oxygen and combustible gas concentrations in the combustion zone. Synergistically with trimethyl phosphate, it promotes the expansion and thickening of the char layer, enhancing its heat insulation and oxygen barrier effects, and inhibiting heat transfer to the lithium battery. Barium metaborate, as an inorganic flame retardant, forms a glassy borate protective layer at high temperatures, covering the surface of the combustion material and preventing heat transfer and combustible volatilization. Synergistically with trimethyl phosphate and melamine cyanurate, it improves the high-temperature resistance and density of the char layer, preventing char layer cracking. The three components work through a synergistic effect of phosphorus, nitrogen, and inorganic components, playing a role in multiple dimensions such as gas phase dilution, condensed phase char formation, solid phase barrier, and heat absorption and cooling, thereby improving the efficiency, stability, and applicability of fire extinguishing additives. Detailed Implementation

[0029] The present application will be further described in detail below with reference to the embodiments.

[0030] Trimethyl phosphate (model: XH-0106) used in the embodiments and comparative examples of this application was purchased from Shandong Xinghai Chemical Co., Ltd.; melamine cyanurate (model: MCA) was purchased from Dongguan Xingyuan Chemical Co., Ltd.; barium metaborate (model: kpl-87787) was purchased from Shandong Kepler Biotechnology Co., Ltd.; decanoic acid (model: 6231) was purchased from Jinan Dehou Chemical Co., Ltd.; lauric acid was purchased from Jinan Shunwang Chemical Co., Ltd.; PEG6000 (item number: peg-6000) was purchased from Shanghai Fuqi Industry & Trade Co., Ltd.; PEG2000 (item number: 20002) was purchased from Shanghai Fuqi Industry & Trade Co., Ltd.; methyl Hydroxyethyl acrylate was purchased from Shandong Qilin Chemical Co., Ltd.; methacrylamide was purchased from Jinan Century Tongda Chemical Co., Ltd.; glycidyl methacrylate was purchased from Shandong Qiyun Chemical Technology Co., Ltd.; nano silica (model: CT49) was purchased from Shandong Nuoyuan Chemical Technology Co., Ltd.; carbon nanotubes (model: CP6134F) were purchased from Suzhou Yilianbang Plastics Technology Co., Ltd.; 2,2,6,6-tetramethylpiperidinol was purchased from Zhongshan Yuanda New Materials Co., Ltd.; sodium dodecyl sulfate (model: dr-09) was purchased from Jinan Daorong Chemical Co., Ltd.; sodium polyacrylate (model: 0687) was purchased from Renqiu Shuangcheng Chemical Products Factory.

[0031] Examples 1-3 provide a fire extinguishing additive for lithium batteries and its preparation method.

[0032] Example 1

[0033] A fire extinguishing additive for lithium batteries comprises the following raw materials in parts by weight: 25 parts of composite flame retardant, 10 parts of phase change microcapsules, 10 parts of free radical scavenger, 3 parts of surfactant, 3 parts of dispersant stabilizer, and 70 parts of deionized water; wherein the composite flame retardant is composed of trimethyl phosphate, melamine cyanurate, and barium metaborate in a mass ratio of 5:2:1, the free radical scavenger is 2,2,6,6-tetramethylpiperidinol, the surfactant is sodium dodecyl sulfate, and the dispersant stabilizer is sodium polyacrylate.

[0034] The preparation of phase change microcapsules includes the following steps:

[0035] Step 1: Mix decanoic acid, lauric acid and polyethylene glycol, heat to 80°C, melt and blend, add nano-silica and carbon nanotubes, stir at 300 rpm for 30 min to obtain the core material. The mass ratio of decanoic acid, lauric acid and polyethylene glycol is 4:2:5. The polyethylene glycol is composed of PEG6000 and PEG2000 in a mass ratio of 10:3. The amount of nano-silica and carbon nanotubes added is 2% and 1% of the total mass of decanoic acid, lauric acid and polyethylene glycol, respectively.

[0036] Step 2: After mixing hydroxyethyl methacrylate, methacrylamide, glycidyl methacrylate and deionized water, potassium persulfate and sodium dodecylbenzene sulfonate are added. Under nitrogen protection, the reaction temperature is 70℃, and the mixture is stirred at 300 rpm for 2 hours to obtain a shell material prepolymer solution. The mass ratio of hydroxyethyl methacrylate, methacrylamide, glycidyl methacrylate and deionized water is 60:10:20:400. The amounts of potassium persulfate and sodium dodecylbenzene sulfonate added are 0.5% and 1% of the total mass of hydroxyethyl methacrylate, methacrylamide and glycidyl methacrylate, respectively.

[0037] Step 3: Add the core material to the shell prepolymer solution and shear at 70°C and a shear speed of 5000 rpm for 20 min. Add N,N'-methylenebisacrylamide and continue the reaction at 70°C for 1 h. Centrifuge at 8000 rpm, wash, and dry to obtain phase change microcapsules. The mass ratio of the core material to the shell prepolymer solution is 1:2, and the amount of N,N'-methylenebisacrylamide added is 2% of the total mass of hydroxyethyl methacrylate, methacrylamide, and glycidyl methacrylate.

[0038] A method for preparing a fire extinguishing additive for lithium batteries includes the following steps:

[0039] Dispersant stabilizer and composite flame retardant are added to deionized water. The mixture is stirred at 30°C and 500 rpm for 20 minutes. The stirring speed is then reduced to 100 rpm, surfactant is added, and stirring continues for 10 minutes. The temperature is then increased to 40°C, free radical scavenger is added, and stirring continues for 20 minutes. Finally, the stirring speed is reduced to 50 rpm, phase change microcapsules are added, and stirring continues for 30 minutes. The homogenization pressure is 20 MPa, and the mixture is homogenized twice to obtain a fire extinguishing additive for lithium batteries.

[0040] Example 2

[0041] A fire extinguishing additive for lithium batteries comprises the following raw materials in parts by weight: 30 parts of composite flame retardant, 11 parts of phase change microcapsules, 12 parts of free radical scavenger, 4.5 parts of surfactant, 4 parts of dispersant stabilizer, and 85 parts of deionized water; wherein the composite flame retardant is composed of trimethyl phosphate, melamine cyanurate, and barium metaborate in a mass ratio of 7:2.5:1.5, the free radical scavenger is 2,2,6,6-tetramethylpiperidinol, the surfactant is sodium dodecyl sulfate, and the dispersant stabilizer is sodium polyacrylate.

[0042] The preparation of phase change microcapsules includes the following steps:

[0043] Step 1: Mix decanoic acid, lauric acid and polyethylene glycol, heat to 82°C, melt and blend, add nano-silica and carbon nanotubes, stir at 400 rpm for 35 min to obtain the core material. The mass ratio of decanoic acid, lauric acid and polyethylene glycol is 6:3:8. The polyethylene glycol is composed of PEG6000 and PEG2000 in a mass ratio of 11:4. The amount of nano-silica and carbon nanotubes added is 3% and 2% of the total mass of decanoic acid, lauric acid and polyethylene glycol, respectively.

[0044] Step 2: After mixing hydroxyethyl methacrylate, methacrylamide, glycidyl methacrylate and deionized water, potassium persulfate and sodium dodecylbenzene sulfonate are added. Under nitrogen protection, the reaction temperature is 75℃, and the mixture is stirred at 450 rpm for 2.5 h to obtain a shell material prepolymer solution. The mass ratio of hydroxyethyl methacrylate, methacrylamide, glycidyl methacrylate and deionized water is 70:15:25:450. The amount of potassium persulfate and sodium dodecylbenzene sulfonate added is 1% and 2% of the total mass of hydroxyethyl methacrylate, methacrylamide and glycidyl methacrylate, respectively.

[0045] Step 3: Add the core material to the shell prepolymer solution and shear at 75°C and 7000 rpm for 25 min. Add N,N'-methylenebisacrylamide and continue the reaction at 72°C for 2 h. Centrifuge at 9000 rpm, wash, and dry to obtain phase change microcapsules. The mass ratio of the core material to the shell prepolymer solution is 1:4, and the amount of N,N'-methylenebisacrylamide added is 3% of the total mass of hydroxyethyl methacrylate, methacrylamide, and glycidyl methacrylate.

[0046] A method for preparing a fire extinguishing additive for lithium batteries includes the following steps:

[0047] Dispersant stabilizer and composite flame retardant are added to deionized water. The mixture is stirred at 35°C and 550 rpm for 25 minutes. The stirring speed is then reduced to 150 rpm, surfactant is added, and stirring continues for 15 minutes. The temperature is then increased to 45°C, free radical scavenger is added, and stirring continues for 30 minutes. Finally, the stirring speed is reduced to 70 rpm, phase change microcapsules are added, and stirring continues for 35 minutes. The homogenization pressure is 25 MPa, and the mixture is homogenized three times to obtain a fire extinguishing additive for lithium batteries.

[0048] Example 3

[0049] A fire extinguishing additive for lithium batteries comprises the following raw materials in parts by weight: 35 parts of composite flame retardant, 12 parts of phase change microcapsules, 15 parts of free radical scavenger, 6 parts of surfactant, 5 parts of dispersion stabilizer, and 100 parts of deionized water; wherein the composite flame retardant is composed of trimethyl phosphate, melamine cyanurate, and barium metaborate in a mass ratio of 8:3:2, the free radical scavenger is 2,2,6,6-tetramethylpiperidinol, the surfactant is sodium dodecyl sulfate, and the dispersion stabilizer is sodium polyacrylate.

[0050] The preparation of phase change microcapsules includes the following steps:

[0051] Step 1: Mix decanoic acid, lauric acid and polyethylene glycol, heat to 85°C, melt and blend, add nano-silica and carbon nanotubes, stir at 500 rpm for 40 min to obtain the core material. The mass ratio of decanoic acid, lauric acid and polyethylene glycol is 8:4:10. The polyethylene glycol is composed of PEG6000 and PEG2000 with a mass ratio of 10-12:3-5. The amount of nano-silica and carbon nanotubes added is 5% and 3% of the total mass of decanoic acid, lauric acid and polyethylene glycol, respectively.

[0052] Step 2: After mixing hydroxyethyl methacrylate, methacrylamide, glycidyl methacrylate and deionized water, potassium persulfate and sodium dodecylbenzene sulfonate are added. Under nitrogen protection, the reaction temperature is 80℃, and the mixture is stirred at 600 rpm for 3 hours to obtain a shell material prepolymer solution. The mass ratio of hydroxyethyl methacrylate, methacrylamide, glycidyl methacrylate and deionized water is 80:20:30:500. The amount of potassium persulfate and sodium dodecylbenzene sulfonate added is 2% and 3% of the total mass of hydroxyethyl methacrylate, methacrylamide and glycidyl methacrylate, respectively.

[0053] Step 3: Add the core material to the shell prepolymer solution and shear at 80°C and 8000 rpm for 30 min. Add N,N'-methylenebisacrylamide and continue the reaction at 75°C for 3 h. Centrifuge at 10000 rpm, wash, and dry to obtain phase change microcapsules. The mass ratio of the core material to the shell prepolymer solution is 1:5, and the amount of N,N'-methylenebisacrylamide added is 5% of the total mass of hydroxyethyl methacrylate, methacrylamide, and glycidyl methacrylate.

[0054] A method for preparing a fire extinguishing additive for lithium batteries includes the following steps:

[0055] Dispersant stabilizer and composite flame retardant are added to deionized water. The mixture is stirred at 40°C and 600 rpm for 30 minutes. The stirring speed is then reduced to 200 rpm, surfactant is added, and stirring continues for 20 minutes. The temperature is then increased to 50°C, free radical scavenger is added, and stirring continues for 40 minutes. Finally, the stirring speed is reduced to 100 rpm, phase change microcapsules are added, and stirring continues for 40 minutes. The homogenization pressure is 30 MPa, and the mixture is homogenized three times to obtain a fire extinguishing additive for lithium batteries.

[0056] Comparative Example 1

[0057] A fire extinguishing additive for lithium batteries comprises the following raw materials in parts by weight: 25 parts of composite flame retardant, 10 parts of phase change microcapsules, 10 parts of free radical scavenger, 3 parts of surfactant, 3 parts of dispersant stabilizer, and 70 parts of deionized water; wherein the composite flame retardant is composed of melamine cyanurate and barium metaborate in a mass ratio of 2:1, the free radical scavenger is 2,2,6,6-tetramethylpiperidinol, the surfactant is sodium dodecyl sulfate, and the dispersant stabilizer is sodium polyacrylate.

[0058] The preparation of phase change microcapsules includes the following steps:

[0059] Step 1: Mix decanoic acid, lauric acid and polyethylene glycol, heat to 80°C, melt and blend, add nano-silica and carbon nanotubes, stir at 300 rpm for 30 min to obtain the core material. The mass ratio of decanoic acid, lauric acid and polyethylene glycol is 4:2:5. The polyethylene glycol is composed of PEG6000 and PEG2000 in a mass ratio of 10:3. The amount of nano-silica and carbon nanotubes added is 2% and 1% of the total mass of decanoic acid, lauric acid and polyethylene glycol, respectively.

[0060] Step 2: After mixing hydroxyethyl methacrylate, methacrylamide, glycidyl methacrylate and deionized water, potassium persulfate and sodium dodecylbenzene sulfonate are added. Under nitrogen protection, the reaction temperature is 70℃, and the mixture is stirred at 300 rpm for 2 hours to obtain a shell material prepolymer solution. The mass ratio of hydroxyethyl methacrylate, methacrylamide, glycidyl methacrylate and deionized water is 60:10:20:400. The amounts of potassium persulfate and sodium dodecylbenzene sulfonate added are 0.5% and 1% of the total mass of hydroxyethyl methacrylate, methacrylamide and glycidyl methacrylate, respectively.

[0061] Step 3: Add the core material to the shell prepolymer solution and shear at 70°C and a shear speed of 5000 rpm for 20 min. Add N,N'-methylenebisacrylamide and continue the reaction at 70°C for 1 h. Centrifuge at 8000 rpm, wash, and dry to obtain phase change microcapsules. The mass ratio of the core material to the shell prepolymer solution is 1:2, and the amount of N,N'-methylenebisacrylamide added is 2% of the total mass of hydroxyethyl methacrylate, methacrylamide, and glycidyl methacrylate.

[0062] A method for preparing a fire extinguishing additive for lithium batteries includes the following steps:

[0063] Dispersant stabilizer and composite flame retardant are added to deionized water. The mixture is stirred at 30°C and 500 rpm for 20 minutes. The stirring speed is then reduced to 100 rpm, surfactant is added, and stirring continues for 10 minutes. The temperature is then increased to 40°C, free radical scavenger is added, and stirring continues for 20 minutes. Finally, the stirring speed is reduced to 50 rpm, phase change microcapsules are added, and stirring continues for 30 minutes. The homogenization pressure is 20 MPa, and the mixture is homogenized twice to obtain a fire extinguishing additive for lithium batteries.

[0064] Comparative Example 2

[0065] A fire extinguishing additive for lithium batteries comprises the following raw materials in parts by weight: 25 parts of composite flame retardant, 10 parts of phase change microcapsules, 10 parts of free radical scavenger, 3 parts of surfactant, 3 parts of dispersant stabilizer, and 70 parts of deionized water; wherein the composite flame retardant is composed of trimethyl phosphate and barium metaborate in a mass ratio of 5:1, the free radical scavenger is 2,2,6,6-tetramethylpiperidinol, the surfactant is sodium dodecyl sulfate, and the dispersant stabilizer is sodium polyacrylate.

[0066] The preparation of phase change microcapsules includes the following steps:

[0067] Step 1: Mix decanoic acid, lauric acid and polyethylene glycol, heat to 80°C, melt and blend, add nano-silica and carbon nanotubes, stir at 300 rpm for 30 min to obtain the core material. The mass ratio of decanoic acid, lauric acid and polyethylene glycol is 4:2:5. The polyethylene glycol is composed of PEG6000 and PEG2000 in a mass ratio of 10:3. The amount of nano-silica and carbon nanotubes added is 2% and 1% of the total mass of decanoic acid, lauric acid and polyethylene glycol, respectively.

[0068] Step 2: After mixing hydroxyethyl methacrylate, methacrylamide, glycidyl methacrylate and deionized water, potassium persulfate and sodium dodecylbenzene sulfonate are added. Under nitrogen protection, the reaction temperature is 70℃, and the mixture is stirred at 300 rpm for 2 hours to obtain a shell material prepolymer solution. The mass ratio of hydroxyethyl methacrylate, methacrylamide, glycidyl methacrylate and deionized water is 60:10:20:400. The amounts of potassium persulfate and sodium dodecylbenzene sulfonate added are 0.5% and 1% of the total mass of hydroxyethyl methacrylate, methacrylamide and glycidyl methacrylate, respectively.

[0069] Step 3: Add the core material to the shell prepolymer solution and shear at 70°C and a shear speed of 5000 rpm for 20 min. Add N,N'-methylenebisacrylamide and continue the reaction at 70°C for 1 h. Centrifuge at 8000 rpm, wash, and dry to obtain phase change microcapsules. The mass ratio of the core material to the shell prepolymer solution is 1:2, and the amount of N,N'-methylenebisacrylamide added is 2% of the total mass of hydroxyethyl methacrylate, methacrylamide, and glycidyl methacrylate.

[0070] A method for preparing a fire extinguishing additive for lithium batteries includes the following steps:

[0071] Dispersant stabilizer and composite flame retardant are added to deionized water. The mixture is stirred at 30°C and 500 rpm for 20 minutes. The stirring speed is then reduced to 100 rpm, surfactant is added, and stirring continues for 10 minutes. The temperature is then increased to 40°C, free radical scavenger is added, and stirring continues for 20 minutes. Finally, the stirring speed is reduced to 50 rpm, phase change microcapsules are added, and stirring continues for 30 minutes. The homogenization pressure is 20 MPa, and the mixture is homogenized twice to obtain a fire extinguishing additive for lithium batteries.

[0072] Comparative Example 3

[0073] A fire extinguishing additive for lithium batteries comprises the following raw materials in parts by weight: 25 parts of composite flame retardant, 10 parts of phase change microcapsules, 10 parts of free radical scavenger, 3 parts of surfactant, 3 parts of dispersant stabilizer, and 70 parts of deionized water; wherein the composite flame retardant is composed of trimethyl phosphate and melamine cyanurate in a mass ratio of 5:2, the free radical scavenger is 2,2,6,6-tetramethylpiperidinol, the surfactant is sodium dodecyl sulfate, and the dispersant stabilizer is sodium polyacrylate.

[0074] The preparation of phase change microcapsules includes the following steps:

[0075] Step 1: Mix decanoic acid, lauric acid and polyethylene glycol, heat to 80°C, melt and blend, add nano-silica and carbon nanotubes, stir at 300 rpm for 30 min to obtain the core material. The mass ratio of decanoic acid, lauric acid and polyethylene glycol is 4:2:5. The polyethylene glycol is composed of PEG6000 and PEG2000 in a mass ratio of 10:3. The amount of nano-silica and carbon nanotubes added is 2% and 1% of the total mass of decanoic acid, lauric acid and polyethylene glycol, respectively.

[0076] Step 2: After mixing hydroxyethyl methacrylate, methacrylamide, glycidyl methacrylate and deionized water, potassium persulfate and sodium dodecylbenzene sulfonate are added. Under nitrogen protection, the reaction temperature is 70℃, and the mixture is stirred at 300 rpm for 2 hours to obtain a shell material prepolymer solution. The mass ratio of hydroxyethyl methacrylate, methacrylamide, glycidyl methacrylate and deionized water is 60:10:20:400. The amounts of potassium persulfate and sodium dodecylbenzene sulfonate added are 0.5% and 1% of the total mass of hydroxyethyl methacrylate, methacrylamide and glycidyl methacrylate, respectively.

[0077] Step 3: Add the core material to the shell prepolymer solution and shear at 70°C and a shear speed of 5000 rpm for 20 min. Add N,N'-methylenebisacrylamide and continue the reaction at 70°C for 1 h. Centrifuge at 8000 rpm, wash, and dry to obtain phase change microcapsules. The mass ratio of the core material to the shell prepolymer solution is 1:2, and the amount of N,N'-methylenebisacrylamide added is 2% of the total mass of hydroxyethyl methacrylate, methacrylamide, and glycidyl methacrylate.

[0078] A method for preparing a fire extinguishing additive for lithium batteries includes the following steps:

[0079] Dispersant stabilizer and composite flame retardant are added to deionized water. The mixture is stirred at 30°C and 500 rpm for 20 minutes. The stirring speed is then reduced to 100 rpm, surfactant is added, and stirring continues for 10 minutes. The temperature is then increased to 40°C, free radical scavenger is added, and stirring continues for 20 minutes. Finally, the stirring speed is reduced to 50 rpm, phase change microcapsules are added, and stirring continues for 30 minutes. The homogenization pressure is 20 MPa, and the mixture is homogenized twice to obtain a fire extinguishing additive for lithium batteries.

[0080] Comparative Example 4

[0081] A fire extinguishing additive for lithium batteries comprises the following raw materials in parts by weight: 25 parts of composite flame retardant, 10 parts of phase change microcapsules, 10 parts of free radical scavenger, 3 parts of surfactant, 3 parts of dispersant stabilizer, and 70 parts of deionized water; wherein the composite flame retardant is composed of trimethyl phosphate, melamine cyanurate, and barium metaborate in a mass ratio of 5:2:1, the free radical scavenger is 2,2,6,6-tetramethylpiperidinol, the surfactant is sodium dodecyl sulfate, and the dispersant stabilizer is sodium polyacrylate.

[0082] The preparation of phase change microcapsules includes the following steps:

[0083] Step 1: Mix decanoic acid, lauric acid and polyethylene glycol, heat to 80°C, melt and blend, add nano-silica and carbon nanotubes, stir at 300 rpm for 30 min to obtain the core material. The mass ratio of decanoic acid, lauric acid and polyethylene glycol is 4:2:5, the polyethylene glycol is PEG6000, and the amount of nano-silica and carbon nanotubes added is 2% and 1% of the total mass of decanoic acid, lauric acid and polyethylene glycol, respectively.

[0084] Step 2: After mixing hydroxyethyl methacrylate, methacrylamide, glycidyl methacrylate and deionized water, potassium persulfate and sodium dodecylbenzene sulfonate are added. Under nitrogen protection, the reaction temperature is 70℃, and the mixture is stirred at 300 rpm for 2 hours to obtain a shell material prepolymer solution. The mass ratio of hydroxyethyl methacrylate, methacrylamide, glycidyl methacrylate and deionized water is 60:10:20:400. The amounts of potassium persulfate and sodium dodecylbenzene sulfonate added are 0.5% and 1% of the total mass of hydroxyethyl methacrylate, methacrylamide and glycidyl methacrylate, respectively.

[0085] Step 3: Add the core material to the shell prepolymer solution and shear at 70°C and a shear speed of 5000 rpm for 20 min. Add N,N'-methylenebisacrylamide and continue the reaction at 70°C for 1 h. Centrifuge at 8000 rpm, wash, and dry to obtain phase change microcapsules. The mass ratio of the core material to the shell prepolymer solution is 1:2, and the amount of N,N'-methylenebisacrylamide added is 2% of the total mass of hydroxyethyl methacrylate, methacrylamide, and glycidyl methacrylate.

[0086] A method for preparing a fire extinguishing additive for lithium batteries includes the following steps:

[0087] Dispersant stabilizer and composite flame retardant are added to deionized water. The mixture is stirred at 30°C and 500 rpm for 20 minutes. The stirring speed is then reduced to 100 rpm, surfactant is added, and stirring continues for 10 minutes. The temperature is then increased to 40°C, free radical scavenger is added, and stirring continues for 20 minutes. Finally, the stirring speed is reduced to 50 rpm, phase change microcapsules are added, and stirring continues for 30 minutes. The homogenization pressure is 20 MPa, and the mixture is homogenized twice to obtain a fire extinguishing additive for lithium batteries.

[0088] Comparative Example 5

[0089] A fire extinguishing additive for lithium batteries comprises the following raw materials in parts by weight: 25 parts of composite flame retardant, 10 parts of phase change microcapsules, 10 parts of free radical scavenger, 3 parts of surfactant, 3 parts of dispersant stabilizer, and 70 parts of deionized water; wherein the composite flame retardant is composed of trimethyl phosphate, melamine cyanurate, and barium metaborate in a mass ratio of 5:2:1, the free radical scavenger is 2,2,6,6-tetramethylpiperidinol, the surfactant is sodium dodecyl sulfate, and the dispersant stabilizer is sodium polyacrylate.

[0090] The preparation of phase change microcapsules includes the following steps:

[0091] Step 1: Mix decanoic acid, lauric acid and polyethylene glycol, heat to 80°C, melt and blend, add nano-silica and carbon nanotubes, stir at 300 rpm for 30 min to obtain the core material. The mass ratio of decanoic acid, lauric acid and polyethylene glycol is 4:2:5, the polyethylene glycol is PEG2000, and the amount of nano-silica and carbon nanotubes added is 2% and 1% of the total mass of decanoic acid, lauric acid and polyethylene glycol, respectively.

[0092] Step 2: After mixing hydroxyethyl methacrylate, methacrylamide, glycidyl methacrylate and deionized water, potassium persulfate and sodium dodecylbenzene sulfonate are added. Under nitrogen protection, the reaction temperature is 70℃, and the mixture is stirred at 300 rpm for 2 hours to obtain a shell material prepolymer solution. The mass ratio of hydroxyethyl methacrylate, methacrylamide, glycidyl methacrylate and deionized water is 60:10:20:400. The amounts of potassium persulfate and sodium dodecylbenzene sulfonate added are 0.5% and 1% of the total mass of hydroxyethyl methacrylate, methacrylamide and glycidyl methacrylate, respectively.

[0093] Step 3: Add the core material to the shell prepolymer solution and shear at 70°C and a shear speed of 5000 rpm for 20 min. Add N,N'-methylenebisacrylamide and continue the reaction at 70°C for 1 h. Centrifuge at 8000 rpm, wash, and dry to obtain phase change microcapsules. The mass ratio of the core material to the shell prepolymer solution is 1:2, and the amount of N,N'-methylenebisacrylamide added is 2% of the total mass of hydroxyethyl methacrylate, methacrylamide, and glycidyl methacrylate.

[0094] A method for preparing a fire extinguishing additive for lithium batteries includes the following steps:

[0095] Dispersant stabilizer and composite flame retardant are added to deionized water. The mixture is stirred at 30°C and 500 rpm for 20 minutes. The stirring speed is then reduced to 100 rpm, surfactant is added, and stirring continues for 10 minutes. The temperature is then increased to 40°C, free radical scavenger is added, and stirring continues for 20 minutes. Finally, the stirring speed is reduced to 50 rpm, phase change microcapsules are added, and stirring continues for 30 minutes. The homogenization pressure is 20 MPa, and the mixture is homogenized twice to obtain a fire extinguishing additive for lithium batteries.

[0096] Comparative Example 6

[0097] A fire extinguishing additive for lithium batteries comprises the following raw materials in parts by weight: 25 parts of composite flame retardant, 10 parts of phase change microcapsules, 10 parts of free radical scavenger, 3 parts of surfactant, 3 parts of dispersant stabilizer, and 70 parts of deionized water; wherein the composite flame retardant is composed of trimethyl phosphate, melamine cyanurate, and barium metaborate in a mass ratio of 5:2:1, the free radical scavenger is 2,2,6,6-tetramethylpiperidinol, the surfactant is sodium dodecyl sulfate, and the dispersant stabilizer is sodium polyacrylate.

[0098] The preparation of phase change microcapsules includes the following steps:

[0099] Step 1: Mix decanoic acid, lauric acid and polyethylene glycol, heat to 80°C, melt and blend, add nano-silica and carbon nanotubes, stir at 300 rpm for 30 min to obtain the core material. The mass ratio of decanoic acid, lauric acid and polyethylene glycol is 4:2:5. The polyethylene glycol is composed of PEG6000 and PEG2000 in a mass ratio of 10:3. The amount of nano-silica and carbon nanotubes added is 2% and 1% of the total mass of decanoic acid, lauric acid and polyethylene glycol, respectively.

[0100] Step 2: After mixing hydroxyethyl methacrylate, glycidyl methacrylate, and deionized water, potassium persulfate and sodium dodecylbenzene sulfonate are added. Under nitrogen protection, the reaction temperature is 70℃, and the mixture is stirred at 300 rpm for 2 hours to obtain a shell material prepolymer solution. The mass ratio of hydroxyethyl methacrylate, glycidyl methacrylate, and deionized water is 65:25:400. The amounts of potassium persulfate and sodium dodecylbenzene sulfonate added are 0.5% and 1% of the total mass of hydroxyethyl methacrylate and glycidyl methacrylate, respectively.

[0101] Step 3: Add the core material to the shell prepolymer solution and shear at 70°C and a shear speed of 5000 rpm for 20 min. Add N,N'-methylenebisacrylamide and continue the reaction at 70°C for 1 h. Centrifuge at 8000 rpm, wash, and dry to obtain phase change microcapsules. The mass ratio of the core material to the shell prepolymer solution is 1:2, and the amount of N,N'-methylenebisacrylamide added is 2% of the total mass of hydroxyethyl methacrylate and glycidyl methacrylate.

[0102] A method for preparing a fire extinguishing additive for lithium batteries includes the following steps:

[0103] Dispersant stabilizer and composite flame retardant are added to deionized water. The mixture is stirred at 30°C and 500 rpm for 20 minutes. The stirring speed is then reduced to 100 rpm, surfactant is added, and stirring continues for 10 minutes. The temperature is then increased to 40°C, free radical scavenger is added, and stirring continues for 20 minutes. Finally, the stirring speed is reduced to 50 rpm, phase change microcapsules are added, and stirring continues for 30 minutes. The homogenization pressure is 20 MPa, and the mixture is homogenized twice to obtain a fire extinguishing additive for lithium batteries.

[0104] Comparative Example 7

[0105] A fire extinguishing additive for lithium batteries comprises the following raw materials in parts by weight: 25 parts of composite flame retardant, 10 parts of phase change microcapsules, 10 parts of free radical scavenger, 3 parts of surfactant, 3 parts of dispersant stabilizer, and 70 parts of deionized water; wherein the composite flame retardant is composed of trimethyl phosphate, melamine cyanurate, and barium metaborate in a mass ratio of 5:2:1, the free radical scavenger is 2,2,6,6-tetramethylpiperidinol, the surfactant is sodium dodecyl sulfate, and the dispersant stabilizer is sodium polyacrylate.

[0106] The preparation of phase change microcapsules includes the following steps:

[0107] Step 1: Mix decanoic acid, lauric acid and polyethylene glycol, heat to 80°C, melt and blend, add nano-silica and carbon nanotubes, stir at 300 rpm for 30 min to obtain the core material. The mass ratio of decanoic acid, lauric acid and polyethylene glycol is 4:2:5. The polyethylene glycol is composed of PEG6000 and PEG2000 in a mass ratio of 10:3. The amount of nano-silica and carbon nanotubes added is 2% and 1% of the total mass of decanoic acid, lauric acid and polyethylene glycol, respectively.

[0108] Step 2: After mixing hydroxyethyl methacrylate, methacrylamide, and deionized water, potassium persulfate and sodium dodecylbenzene sulfonate are added. Under nitrogen protection, the reaction temperature is 70℃, and the mixture is stirred at 300 rpm for 2 hours to obtain a shell material prepolymer solution. The mass ratio of hydroxyethyl methacrylate, methacrylamide, and deionized water is 70:20:400. The amounts of potassium persulfate and sodium dodecylbenzene sulfonate added are 0.5% and 1% of the total mass of hydroxyethyl methacrylate and methacrylamide, respectively.

[0109] Step 3: Add the core material to the shell prepolymer solution and shear at 70°C and a shear speed of 5000 rpm for 20 min. Add N,N'-methylenebisacrylamide and continue the reaction at 70°C for 1 h. Centrifuge at 8000 rpm, wash, and dry to obtain phase change microcapsules. The mass ratio of the core material to the shell prepolymer solution is 1:2, and the amount of N,N'-methylenebisacrylamide added is 2% of the total mass of hydroxyethyl methacrylate and methacrylamide.

[0110] A method for preparing a fire extinguishing additive for lithium batteries includes the following steps:

[0111] Dispersant stabilizer and composite flame retardant are added to deionized water. The mixture is stirred at 30°C and 500 rpm for 20 minutes. The stirring speed is then reduced to 100 rpm, surfactant is added, and stirring continues for 10 minutes. The temperature is then increased to 40°C, free radical scavenger is added, and stirring continues for 20 minutes. Finally, the stirring speed is reduced to 50 rpm, phase change microcapsules are added, and stirring continues for 30 minutes. The homogenization pressure is 20 MPa, and the mixture is homogenized twice to obtain a fire extinguishing additive for lithium batteries.

[0112] Performance testing

[0113] The performance parameters of the fire extinguishing additives for lithium batteries prepared in Examples 1-3 and Comparative Examples 1-7 of this application are as follows:

[0114] Take a 256650 cylindrical battery pack with four thermocouples connected to its surface, and heat it continuously until it causes thermal runaway. When the lithium battery explodes and bursts into flames, quickly activate the spray system to spray the fire extinguishing additives prepared in Examples 1-3 and Comparative Examples 1-7. Record the fire extinguishing time, the amount of fire extinguishing additive used, the cooling rate, and the highest surface temperature of the lithium-ion battery after fire extinguishing. At the same time, observe whether the lithium battery reignites.

[0115] The specific test results are shown in Table 1 below.

[0116] Table 1. Performance parameters of the fire extinguishing additives for lithium batteries prepared in Examples 1-3 and Comparative Examples 1-7.

[0117]

[0118] As shown in Table 1, the fire extinguishing additive for lithium-ion batteries prepared in this application has the advantages of low fire extinguishing agent dosage, fast fire extinguishing speed, ability to extinguish flames in a short time, high cooling rate, rapid reduction of the fire temperature of lithium-ion batteries, no reignition phenomenon, elimination of fire hazards, strong assistance for fire fighting, and protection of people's lives and property safety.

[0119] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A fire extinguishing additive for lithium batteries, characterized in that, The raw materials include the following parts by weight: 25-35 parts of composite flame retardant, 10-12 parts of phase change microcapsules, 10-15 parts of free radical scavenger, 3-6 parts of surfactant, 3-5 parts of dispersant stabilizer, and 70-100 parts of deionized water; The composite flame retardant is composed of trimethyl phosphate, melamine cyanurate and barium metaborate in a mass ratio of 5-8:2-3:1-2; The preparation of the phase change microcapsules includes the following steps: Step 1: Mix decanoic acid, lauric acid and polyethylene glycol, heat to 80-85℃, melt and blend, add nano-silica and carbon nanotubes, stir at 300-500 rpm for 30-40 minutes to obtain the core material; Step 2: Mix hydroxyethyl methacrylate, methacrylamide, glycidyl methacrylate and deionized water, then add potassium persulfate and sodium dodecylbenzene sulfonate. Under nitrogen protection, the reaction temperature is 70-80℃, and the mixture is stirred for 2-3 hours to obtain the shell material prepolymer solution. Step 3: Add the core material to the shell material prepolymer solution and shear at 70-80℃ with a shear speed of 5000-8000 rpm for 20-30 minutes. Add N,N'-methylenebisacrylamide and continue the reaction at 70-75℃ for 1-3 hours. Centrifuge, wash, and dry to obtain phase change microcapsules. In step 1, the mass ratio of decanoic acid, lauric acid, and polyethylene glycol is 4-8:2-4:5-10; the polyethylene glycol is composed of PEG6000 and PEG2000 in a mass ratio of 10-12:3-5; the added amounts of nano-silica and carbon nanotubes are 2-5% and 1-3% of the total mass of decanoic acid, lauric acid, and polyethylene glycol, respectively. In step 2, the mass ratio of hydroxyethyl methacrylate, methacrylamide, glycidyl methacrylate, and deionized water is 60-80:10-20:20-30:400-500; the amounts of potassium persulfate and sodium dodecylbenzenesulfonate added are 0.5-2% and 1-3% of the total mass of hydroxyethyl methacrylate, methacrylamide, and glycidyl methacrylate, respectively. In step 3, the mass ratio of the core material and shell material prepolymer solution is 1:2-5; the amount of N,N'-methylenebisacrylamide added is 2-5% of the total mass of hydroxyethyl methacrylate, methacrylamide and glycidyl methacrylate.

2. The fire extinguishing additive for lithium batteries according to claim 1, characterized in that, The free radical scavenger is one or more of 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene, 2,2,6,6-tetramethylpiperidinol, and 4-hydroxy-2,2,6,6-tetramethylpiperidin-1-oxy.

3. The fire extinguishing additive for lithium batteries according to claim 1, characterized in that, The surfactant is one or more of sodium dodecyl sulfate, fatty alcohol polyoxyethylene ether, and polysorbate; the dispersant stabilizer is one or more of polyvinylpyrrolidone, sodium polyacrylate, and gum arabic.

4. A method for preparing a fire extinguishing additive for lithium batteries as described in any one of claims 1-3, characterized in that, Includes the following steps: Add a dispersant stabilizer and a composite flame retardant to deionized water, and stir at 30-40℃ with a stirring speed of 500-600 rpm for 20-30 minutes. Reduce the stirring speed to 100-200 rpm, add a surfactant, and continue stirring for 10-20 minutes. Increase the temperature to 40-50℃, add a free radical scavenger, and stir for 20-40 minutes. Finally, reduce the stirring speed to 50-100 rpm, add phase change microcapsules, and stir for 30-40 minutes. After homogenization, the fire extinguishing additive for lithium batteries is obtained.

5. The method for preparing the fire extinguishing additive for lithium batteries according to claim 4, characterized in that, The homogenization pressure is 20-30 MPa, and the homogenization is performed 2-3 times.

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