Fire extinguishing additive for lithium battery and preparation method of fire extinguishing additive

Abstract

The invention relates to the technical field of lithium ion fire safety preparation, in particular to a fire extinguishing additive for a lithium battery and a preparation method of the fire extinguishing additive. The fire extinguishing additive comprises the following raw materials: a composite flame retardant, a phase change microcapsule, a free radical trapping agent, a surfactant, a dispersion stabilizer and deionized water. The preparation method of the fire extinguishing additive comprises the following steps: adding the dispersion stabilizer and the composite flame retardant into the deionized water, uniformly stirring, reducing the stirring speed, adding the surfactant, continuously stirring, raising the temperature to 40-50 DEG C, adding the free radical scavenger, finally reducing the stirring speed, adding the phase change microcapsules, and homogenizing to obtain the fire extinguishing additive. The fire extinguishing additive for the lithium battery is obtained. The prepared fire extinguishing additive has the advantages of small dosage, high fire extinguishing speed, capability of extinguishing flames in a short time, high cooling rate and no after-combustion phenomenon.

Description

Technical Field

[0001] The present application relates to the technical field of lithium ion fire safety preparation, and more specifically, to a fire extinguishing additive for lithium batteries and a preparation method thereof. Background Art

[0002] With the widespread adoption of lithium batteries in electric vehicles, portable electronic devices, and other fields, lithium battery fires are becoming increasingly common, and their extinguishing is becoming increasingly difficult. This is primarily due to the fact that lithium battery fires burn extremely violently, reaching extremely high temperatures, and the rapid spread of thermal runaway. Furthermore, even after the fire is extinguished, chemical reactions within the battery continue, generating flammable gases. This requires continued cooling to prevent re-ignition.

[0003] Existing fire extinguishing agents for lithium batteries are mainly divided into dry powder fire extinguishing agents, water-based fire extinguishing agents and gas fire extinguishing agents. However, although dry powder fire extinguishing agents can quickly extinguish open flames, they cannot reduce the temperature inside the battery, resulting in a continuous thermal runaway reaction, which is prone to reignition or even explosion; water-based fire extinguishing agents isolate oxygen and reduce temperature through a water film, but the inhibitory effect on deep thermal runaway inside the lithium battery is insufficient, requiring a large amount of continuous water spraying, which is difficult to operate, and water spraying may cause a secondary short circuit in the battery, especially in high-voltage battery systems, which poses a safety hazard; gas fire extinguishing agents have high fire extinguishing efficiency and are environmentally friendly, but they are expensive and have poor cooling ability. In open spaces or poorly ventilated environments, the gas concentration is difficult to maintain, affecting the fire extinguishing effect. Based on the above defects, the present application provides a fire extinguishing additive for lithium batteries and a preparation method thereof, which are used to ensure fire safety during the use of lithium batteries. Summary of the Invention

[0004] In order to solve the technical problems mentioned in the background technology, the present application provides a fire extinguishing additive for lithium batteries and a preparation method thereof.

[0005] In a first aspect, the present application provides a fire extinguishing additive for lithium batteries, which adopts 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 a composite flame retardant, 10-12 parts of phase change microcapsules, 10-15 parts of a free radical scavenger, 3-6 parts of a surfactant, 3-5 parts of a dispersion 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-oxyl.

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

[0010] Preferably, the dispersion stabilizer is one or more of polyvinyl pyrrolidone, sodium polyacrylate, and gum arabic.

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

[0012] Step 1: capric acid, lauric acid and polyethylene glycol are mixed, heated to 80-85° C., melt-blended, and nano-silica and carbon nanotubes are added, and stirred at a stirring speed of 300-500 rpm for 30-40 minutes to obtain a core material;

[0013] Step 2: After mixing hydroxyethyl methacrylate, methacrylamide, glycidyl methacrylate and deionized water, potassium persulfate and sodium dodecylbenzenesulfonate are added, and the reaction temperature is 70-80° C. under nitrogen protection, and the reaction is stirred for 2-3 hours to obtain a shell material prepolymer solution;

[0014] Step 3: Add the core material to the shell material prepolymer solution, high-speed shear for 20-30 min at 70-80°C and a shear speed of 5000-8000 rpm, add N,N'-methylenebisacrylamide, continue the reaction at 70-75°C for 1-3 h, centrifuge, wash, and dry to obtain phase change microcapsules.

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

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

[0017] Preferably, the added amounts of nano-silica and carbon nanotubes in step 1 are 2-5% and 1-3% of the total mass of capric 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, the addition amounts of potassium persulfate and sodium dodecylbenzenesulfonate in step 2 are 0.5-2% and 1-3% of the total mass of hydroxyethyl methacrylate, methacrylamide and glycidyl methacrylate, respectively.

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

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

[0022] In a second aspect, the present application also provides a method for preparing a fire extinguishing additive for lithium batteries, which adopts the following technical solution:

[0023] Add a dispersion stabilizer and a composite flame retardant to deionized water, stir at 30-40°C with a stirring speed of 500-600 rpm for 20-30 minutes, reduce the stirring speed to 100-200 rpm, add a surfactant, continue stirring for 10-20 minutes, increase the temperature to 40-50°C, add a free radical scavenger, stir for 20-40 minutes, finally reduce the stirring speed to 50-100 rpm, add phase change microcapsules, stir for 30-40 minutes, and after homogenization, obtain a fire extinguishing additive for lithium batteries.

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

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

[0026] The present application adds phase change microcapsules in the preparation of fire extinguishing additives, which can efficiently absorb heat, quickly reduce temperature, inhibit thermal runaway and prevent re-ignition. The core material of the phase change microcapsule is composed of capric acid, lauric acid and polyethylene glycol. The three form a low eutectic mixture with a high phase change latent heat. When the temperature of the lithium battery rises due to thermal runaway, the core material absorbs a large amount of heat through phase change, which can effectively reduce the local temperature and inhibit the rapid temperature rise, thereby preventing the spread of thermal runaway. The phase change microcapsules and the chemical flame retardant of the composite flame retardant and the chain reaction inhibition of the free radical scavenger form a synergistic effect. After selecting PEG6000 and PEG2000 for compounding, the phase change temperature range of the core material is more in line with the temperature gradient of thermal runaway of the lithium battery, realizing staged and multi-temperature zone heat absorption, and improving the ability to regulate the battery temperature. In addition, the PEG6000 molecular chain is longer, which can increase the viscosity and structural strength of the core material, prevent the low melting point component from excessive flow or leakage after melting, and improve the filling stability of the core material in the capsule. The shorter molecular chain of PEG2000 reduces system viscosity, improves compatibility with capric acid and lauric acid, and promotes uniform dispersion during melt blending, avoiding potential problems such as excessive viscosity and poor fluidity. This balances the core material's viscosity, melting point, and mechanical strength, allowing it to maintain a certain level of fluidity at high temperatures to fully absorb heat while also preventing leakage. The nanosilica and carbon nanotubes added to the core material exhibit 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 core material's structural stability, preventing capsule rupture caused by volume expansion during phase change. Furthermore, the phase change microcapsules, combined with the dispersion stabilizer and surfactant in the system, can be evenly dispersed in the aqueous solution, ensuring rapid contact with the battery surface during fire extinguishing, thereby exerting a cooling effect.

[0027] In the preparation of the shell material of the phase-change microcapsule, the present application selects three monomers through functional group complementarity and structural synergy, so that the shell material has high mechanical strength, heat resistance, hydrophilicity and interface compatibility. The flexible chain segment of hydroxyethyl methacrylate reduces the rigidity of the shell material and avoids brittle cracking of the shell layer at high temperature; the polar groups and cross-linked structure of methacrylamide and glycidyl methacrylate improve the hardness and heat resistance of the shell material, so that the microcapsule maintains structural integrity in the high temperature environment of lithium battery fire, strengthens the core-shell interface bonding, and prevents core material leakage. In addition, the polymer network structure of the shell material can not only protect the core material, but also form a layer of lightweight thermal insulation film on the surface of the lithium battery to block oxygen and heat transfer and assist in flame retardancy. At the same time, the phase-change microcapsules do not directly react with the composite flame retardant and free radical scavenger, avoiding compatibility issues between the components and ensuring the chemical stability of the fire extinguishing additive during storage and use.

[0028] This application decomposes trimethyl phosphate at high temperature to produce phosphorus-containing free radicals, capture active free radicals in the combustion chain reaction, and inhibit flame propagation. The high-temperature decomposition to produce phosphoric acid and polyphosphoric acid can promote the dehydration and carbonization of combustibles, forming a dense carbon layer, isolating heat and oxygen, and reducing the release of combustible gases. Melamine cyanurate decomposes at high temperatures to produce non-combustible gases such as NH3 and N2, which dilute the oxygen and combustible gas concentrations in the combustion area. It cooperates with trimethyl phosphate to promote the expansion and thickening of the carbon layer, enhance the heat insulation and oxygen isolation effects of the carbon layer, and inhibit heat transfer to the interior of 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, preventing heat transfer and volatilization of combustibles; it cooperates with trimethyl phosphate and melamine cyanurate to improve the high temperature resistance and density of the carbon layer and prevent the carbon layer from cracking. The three components play a role in multiple dimensions such as gas phase dilution, condensed phase carbonization, solid phase barrier and heat absorption and cooling through the phosphorus-nitrogen-inorganic synergistic effect, thereby improving the efficiency, stability and scope of application of fire extinguishing additives. DETAILED DESCRIPTION

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

[0030] Trimethyl phosphate (model: XH-0106) used in the examples and comparative examples of the present 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.; capric 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 and Trade Co., Ltd.; PEG2000 (item number: 20002) was purchased from Shanghai Fuqi Industry and 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.; nanosilica (model: CT49) was purchased from Shandong Nuoyuan Chemical Technology Co., Ltd.; carbon nanotubes (model: CP6134F) were purchased from Suzhou Yilianbang Plastic 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 a preparation method thereof.

[0032] Example 1

[0033] A fire extinguishing additive for lithium batteries comprises the following raw materials in parts by weight: 25 parts of a composite flame retardant, 10 parts of phase change microcapsules, 10 parts of a free radical scavenger, 3 parts of a surfactant, 3 parts of a dispersion 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 lauryl sulfate, and the dispersion stabilizer is sodium polyacrylate.

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

[0035] Step 1, capric acid, lauric acid and polyethylene glycol are mixed, heated to 80°C, melt-blended, and nano-silica and carbon nanotubes are added. The mixture is stirred at a stirring speed of 300 rpm for 30 minutes to obtain a core material, wherein the mass ratio of capric acid, lauric acid and polyethylene glycol is 4:2:5, the polyethylene glycol is composed of PEG6000 and PEG2000 with a mass ratio of 10:3, and the added amounts of nano-silica and carbon nanotubes are 2% and 1% of the total mass of capric acid, lauric acid and polyethylene glycol, respectively;

[0036] Step 2: After mixing hydroxyethyl methacrylate, methacrylamide, glycidyl methacrylate, and deionized water, potassium persulfate and sodium dodecylbenzenesulfonate were added, and the mixture was stirred at 70° C. and 300 rpm under nitrogen protection for 2 hours to obtain a shell material prepolymer solution, wherein the mass ratio of hydroxyethyl methacrylate, methacrylamide, glycidyl methacrylate, and deionized water was 60:10:20:400, and the addition amounts of potassium persulfate and sodium dodecylbenzenesulfonate were 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 material prepolymer solution, perform high-speed shearing at 70°C and a shear speed of 5000 rpm for 20 minutes, add N,N'-methylenebisacrylamide, continue the reaction at 70°C for 1 hour, centrifuge at a centrifugal speed of 8000 rpm, wash, and dry to obtain phase change microcapsules, wherein the mass ratio of the core material to the shell material 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 comprises the following steps:

[0039] Add a dispersion stabilizer and a composite flame retardant to deionized water, stir at 30°C with a stirring speed of 500 rpm for 20 minutes, reduce the stirring speed to 100 rpm, add a surfactant, continue stirring for 10 minutes, increase the temperature to 40°C, add a free radical scavenger, and stir for 20 minutes. Finally, reduce the stirring speed to 50 rpm, add phase change microcapsules, stir for 30 minutes, and homogenize twice at a homogenization pressure of 20 MPa 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 a composite flame retardant, 11 parts of phase change microcapsules, 12 parts of a free radical scavenger, 4.5 parts of a surfactant, 4 parts of a dispersion 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 lauryl sulfate, and the dispersion stabilizer is sodium polyacrylate.

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

[0043] Step 1, capric acid, lauric acid and polyethylene glycol are mixed, heated to 82°C, melt-blended, nano-silica and carbon nanotubes are added, and stirred at a stirring speed of 400 rpm for 35 minutes to obtain a core material, wherein the mass ratio of capric acid, lauric acid and polyethylene glycol is 6:3:8, the polyethylene glycol is composed of PEG6000 and PEG2000 with a mass ratio of 11:4, and the added amounts of nano-silica and carbon nanotubes are 3% and 2% of the total mass of capric acid, lauric acid and polyethylene glycol, respectively;

[0044] Step 2: After mixing hydroxyethyl methacrylate, methacrylamide, glycidyl methacrylate, and deionized water, potassium persulfate and sodium dodecylbenzenesulfonate were added, and the reaction was stirred at 75° C. and 450 rpm under nitrogen protection for 2.5 hours to obtain a shell material prepolymer solution, wherein the mass ratio of hydroxyethyl methacrylate, methacrylamide, glycidyl methacrylate, and deionized water was 70:15:25:450, and the addition amounts of potassium persulfate and sodium dodecylbenzenesulfonate were 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 material prepolymer solution, perform high-speed shearing at 75°C and a shear speed of 7000 rpm for 25 minutes, add N,N'-methylenebisacrylamide, continue the reaction at 72°C for 2 hours, centrifuge at a centrifugal speed of 9000 rpm, wash, and dry to obtain phase change microcapsules, wherein the mass ratio of the core material to the shell material 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 comprises the following steps:

[0047] Add a dispersion stabilizer and a composite flame retardant to deionized water, stir at 35°C with a stirring speed of 550 rpm for 25 minutes, reduce the stirring speed to 150 rpm, add a surfactant, continue stirring for 15 minutes, increase the temperature to 45°C, add a free radical scavenger, and stir for 30 minutes. Finally, reduce the stirring speed to 70 rpm, add phase change microcapsules, stir for 35 minutes, and homogenize at a homogenization pressure of 25 MPa for 3 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 a composite flame retardant, 12 parts of phase change microcapsules, 15 parts of a free radical scavenger, 6 parts of a surfactant, 5 parts of a 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 lauryl sulfate, and the dispersion stabilizer is sodium polyacrylate.

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

[0051] Step 1, after capric acid, lauric acid and polyethylene glycol are mixed, heated to 85°C, melt-blended, nano-silica and carbon nanotubes are added, and stirred at a stirring speed of 500 rpm for 40 minutes to obtain a core material, wherein the mass ratio of capric 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, and the added amounts of nano-silica and carbon nanotubes are 5% and 3% of the total mass of capric acid, lauric acid and polyethylene glycol, respectively;

[0052] Step 2: After mixing hydroxyethyl methacrylate, methacrylamide, glycidyl methacrylate, and deionized water, potassium persulfate and sodium dodecylbenzenesulfonate were added, and the mixture was stirred at 80° C. and 600 rpm under nitrogen protection for 3 hours to obtain a shell material prepolymer solution, wherein the mass ratio of hydroxyethyl methacrylate, methacrylamide, glycidyl methacrylate, and deionized water was 80:20:30:500, and the addition amounts of potassium persulfate and sodium dodecylbenzenesulfonate were 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 material prepolymer solution, perform high-speed shearing at 80°C and a shear speed of 8000 rpm for 30 minutes, add N,N'-methylenebisacrylamide, continue the reaction at 75°C for 3 hours, centrifuge at a centrifugal speed of 10000 rpm, wash, and dry to obtain phase change microcapsules, wherein the mass ratio of the core material to the shell material 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 comprises the following steps:

[0055] Add a dispersion stabilizer and a composite flame retardant to deionized water, stir at 40°C with a stirring speed of 600 rpm for 30 minutes, reduce the stirring speed to 200 rpm, add a surfactant, continue stirring for 20 minutes, increase the temperature to 50°C, add a free radical scavenger, and stir for 40 minutes. Finally, reduce the stirring speed to 100 rpm, add phase change microcapsules, stir for 40 minutes, and homogenize at a homogenization pressure of 30 MPa for 3 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 a composite flame retardant, 10 parts of phase change microcapsules, 10 parts of a free radical scavenger, 3 parts of a surfactant, 3 parts of a dispersion 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 lauryl sulfate, and the dispersion stabilizer is sodium polyacrylate.

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

[0059] Step 1, capric acid, lauric acid and polyethylene glycol are mixed, heated to 80°C, melt-blended, and nano-silica and carbon nanotubes are added. The mixture is stirred at a stirring speed of 300 rpm for 30 minutes to obtain a core material, wherein the mass ratio of capric acid, lauric acid and polyethylene glycol is 4:2:5, the polyethylene glycol is composed of PEG6000 and PEG2000 with a mass ratio of 10:3, and the added amounts of nano-silica and carbon nanotubes are 2% and 1% of the total mass of capric acid, lauric acid and polyethylene glycol, respectively;

[0060] Step 2: After mixing hydroxyethyl methacrylate, methacrylamide, glycidyl methacrylate, and deionized water, potassium persulfate and sodium dodecylbenzenesulfonate were added, and the mixture was stirred at 70° C. and 300 rpm under nitrogen protection for 2 hours to obtain a shell material prepolymer solution, wherein the mass ratio of hydroxyethyl methacrylate, methacrylamide, glycidyl methacrylate, and deionized water was 60:10:20:400, and the addition amounts of potassium persulfate and sodium dodecylbenzenesulfonate were 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 material prepolymer solution, perform high-speed shearing at 70°C and a shear speed of 5000 rpm for 20 minutes, add N,N'-methylenebisacrylamide, continue the reaction at 70°C for 1 hour, centrifuge at a centrifugal speed of 8000 rpm, wash, and dry to obtain phase change microcapsules, wherein the mass ratio of the core material to the shell material 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 comprises the following steps:

[0063] Add a dispersion stabilizer and a composite flame retardant to deionized water, stir at 30°C with a stirring speed of 500 rpm for 20 minutes, reduce the stirring speed to 100 rpm, add a surfactant, continue stirring for 10 minutes, increase the temperature to 40°C, add a free radical scavenger, and stir for 20 minutes. Finally, reduce the stirring speed to 50 rpm, add phase change microcapsules, stir for 30 minutes, and homogenize twice at a homogenization pressure of 20 MPa 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 a composite flame retardant, 10 parts of phase change microcapsules, 10 parts of a free radical scavenger, 3 parts of a surfactant, 3 parts of a dispersion 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 lauryl sulfate, and the dispersion stabilizer is sodium polyacrylate.

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

[0067] Step 1, capric acid, lauric acid and polyethylene glycol are mixed, heated to 80°C, melt-blended, and nano-silica and carbon nanotubes are added. The mixture is stirred at a stirring speed of 300 rpm for 30 minutes to obtain a core material, wherein the mass ratio of capric acid, lauric acid and polyethylene glycol is 4:2:5, the polyethylene glycol is composed of PEG6000 and PEG2000 with a mass ratio of 10:3, and the added amounts of nano-silica and carbon nanotubes are 2% and 1% of the total mass of capric acid, lauric acid and polyethylene glycol, respectively;

[0068] Step 2: After mixing hydroxyethyl methacrylate, methacrylamide, glycidyl methacrylate, and deionized water, potassium persulfate and sodium dodecylbenzenesulfonate were added, and the mixture was stirred at 70° C. and 300 rpm under nitrogen protection for 2 hours to obtain a shell material prepolymer solution, wherein the mass ratio of hydroxyethyl methacrylate, methacrylamide, glycidyl methacrylate, and deionized water was 60:10:20:400, and the addition amounts of potassium persulfate and sodium dodecylbenzenesulfonate were 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 material prepolymer solution, perform high-speed shearing at 70°C and a shear speed of 5000 rpm for 20 minutes, add N,N'-methylenebisacrylamide, continue the reaction at 70°C for 1 hour, centrifuge at a centrifugal speed of 8000 rpm, wash, and dry to obtain phase change microcapsules, wherein the mass ratio of the core material to the shell material 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 comprises the following steps:

[0071] Add a dispersion stabilizer and a composite flame retardant to deionized water, stir at 30°C with a stirring speed of 500 rpm for 20 minutes, reduce the stirring speed to 100 rpm, add a surfactant, continue stirring for 10 minutes, increase the temperature to 40°C, add a free radical scavenger, and stir for 20 minutes. Finally, reduce the stirring speed to 50 rpm, add phase change microcapsules, stir for 30 minutes, and homogenize twice at a homogenization pressure of 20 MPa 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 a composite flame retardant, 10 parts of phase change microcapsules, 10 parts of a free radical scavenger, 3 parts of a surfactant, 3 parts of a dispersion 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 lauryl sulfate, and the dispersion stabilizer is sodium polyacrylate.

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

[0075] Step 1, capric acid, lauric acid and polyethylene glycol are mixed, heated to 80°C, melt-blended, and nano-silica and carbon nanotubes are added. The mixture is stirred at a stirring speed of 300 rpm for 30 minutes to obtain a core material, wherein the mass ratio of capric acid, lauric acid and polyethylene glycol is 4:2:5, the polyethylene glycol is composed of PEG6000 and PEG2000 with a mass ratio of 10:3, and the added amounts of nano-silica and carbon nanotubes are 2% and 1% of the total mass of capric acid, lauric acid and polyethylene glycol, respectively;

[0076] Step 2: After mixing hydroxyethyl methacrylate, methacrylamide, glycidyl methacrylate, and deionized water, potassium persulfate and sodium dodecylbenzenesulfonate were added, and the mixture was stirred at 70° C. and 300 rpm under nitrogen protection for 2 hours to obtain a shell material prepolymer solution, wherein the mass ratio of hydroxyethyl methacrylate, methacrylamide, glycidyl methacrylate, and deionized water was 60:10:20:400, and the addition amounts of potassium persulfate and sodium dodecylbenzenesulfonate were 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 material prepolymer solution, perform high-speed shearing at 70°C and a shear speed of 5000 rpm for 20 minutes, add N,N'-methylenebisacrylamide, continue the reaction at 70°C for 1 hour, centrifuge at a centrifugal speed of 8000 rpm, wash, and dry to obtain phase change microcapsules, wherein the mass ratio of the core material to the shell material 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 comprises the following steps:

[0079] Add a dispersion stabilizer and a composite flame retardant to deionized water, stir at 30°C with a stirring speed of 500 rpm for 20 minutes, reduce the stirring speed to 100 rpm, add a surfactant, continue stirring for 10 minutes, increase the temperature to 40°C, add a free radical scavenger, and stir for 20 minutes. Finally, reduce the stirring speed to 50 rpm, add phase change microcapsules, stir for 30 minutes, and homogenize twice at a homogenization pressure of 20 MPa 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 a composite flame retardant, 10 parts of phase change microcapsules, 10 parts of a free radical scavenger, 3 parts of a surfactant, 3 parts of a dispersion 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 lauryl sulfate, and the dispersion stabilizer is sodium polyacrylate.

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

[0083] Step 1, capric acid, lauric acid and polyethylene glycol are mixed, heated to 80°C, melt-blended, and nano-silica and carbon nanotubes are added. The mixture is stirred at a stirring speed of 300 rpm for 30 minutes to obtain a core material, wherein the mass ratio of capric acid, lauric acid and polyethylene glycol is 4:2:5, the polyethylene glycol is PEG6000, and the added amounts of nano-silica and carbon nanotubes are 2% and 1% of the total mass of capric acid, lauric acid and polyethylene glycol, respectively;

[0084] Step 2: After mixing hydroxyethyl methacrylate, methacrylamide, glycidyl methacrylate, and deionized water, potassium persulfate and sodium dodecylbenzenesulfonate were added, and the mixture was stirred at 70° C. and 300 rpm under nitrogen protection for 2 hours to obtain a shell material prepolymer solution, wherein the mass ratio of hydroxyethyl methacrylate, methacrylamide, glycidyl methacrylate, and deionized water was 60:10:20:400, and the addition amounts of potassium persulfate and sodium dodecylbenzenesulfonate were 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 material prepolymer solution, perform high-speed shearing at 70°C and a shear speed of 5000 rpm for 20 minutes, add N,N'-methylenebisacrylamide, continue the reaction at 70°C for 1 hour, centrifuge at a centrifugal speed of 8000 rpm, wash, and dry to obtain phase change microcapsules, wherein the mass ratio of the core material to the shell material 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 comprises the following steps:

[0087] Add a dispersion stabilizer and a composite flame retardant to deionized water, stir at 30°C with a stirring speed of 500 rpm for 20 minutes, reduce the stirring speed to 100 rpm, add a surfactant, continue stirring for 10 minutes, increase the temperature to 40°C, add a free radical scavenger, and stir for 20 minutes. Finally, reduce the stirring speed to 50 rpm, add phase change microcapsules, stir for 30 minutes, and homogenize twice at a homogenization pressure of 20 MPa 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 a composite flame retardant, 10 parts of phase change microcapsules, 10 parts of a free radical scavenger, 3 parts of a surfactant, 3 parts of a dispersion 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 lauryl sulfate, and the dispersion stabilizer is sodium polyacrylate.

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

[0091] Step 1, capric acid, lauric acid and polyethylene glycol are mixed, heated to 80°C, melt-blended, and nano-silica and carbon nanotubes are added. The mixture is stirred at a stirring speed of 300 rpm for 30 minutes to obtain a core material, wherein the mass ratio of capric acid, lauric acid and polyethylene glycol is 4:2:5, the polyethylene glycol is PEG2000, and the added amounts of nano-silica and carbon nanotubes are 2% and 1% of the total mass of capric acid, lauric acid and polyethylene glycol, respectively;

[0092] Step 2: After mixing hydroxyethyl methacrylate, methacrylamide, glycidyl methacrylate, and deionized water, potassium persulfate and sodium dodecylbenzenesulfonate were added, and the mixture was stirred at 70° C. and 300 rpm under nitrogen protection for 2 hours to obtain a shell material prepolymer solution, wherein the mass ratio of hydroxyethyl methacrylate, methacrylamide, glycidyl methacrylate, and deionized water was 60:10:20:400, and the addition amounts of potassium persulfate and sodium dodecylbenzenesulfonate were 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 material prepolymer solution, perform high-speed shearing at 70°C and a shear speed of 5000 rpm for 20 minutes, add N,N'-methylenebisacrylamide, continue the reaction at 70°C for 1 hour, centrifuge at a centrifugal speed of 8000 rpm, wash, and dry to obtain phase change microcapsules, wherein the mass ratio of the core material to the shell material 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 comprises the following steps:

[0095] Add a dispersion stabilizer and a composite flame retardant to deionized water, stir at 30°C with a stirring speed of 500 rpm for 20 minutes, reduce the stirring speed to 100 rpm, add a surfactant, continue stirring for 10 minutes, increase the temperature to 40°C, add a free radical scavenger, and stir for 20 minutes. Finally, reduce the stirring speed to 50 rpm, add phase change microcapsules, stir for 30 minutes, and homogenize twice at a homogenization pressure of 20 MPa 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 a composite flame retardant, 10 parts of phase change microcapsules, 10 parts of a free radical scavenger, 3 parts of a surfactant, 3 parts of a dispersion 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 lauryl sulfate, and the dispersion stabilizer is sodium polyacrylate.

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

[0099] Step 1, capric acid, lauric acid and polyethylene glycol are mixed, heated to 80°C, melt-blended, and nano-silica and carbon nanotubes are added. The mixture is stirred at a stirring speed of 300 rpm for 30 minutes to obtain a core material, wherein the mass ratio of capric acid, lauric acid and polyethylene glycol is 4:2:5, the polyethylene glycol is composed of PEG6000 and PEG2000 with a mass ratio of 10:3, and the added amounts of nano-silica and carbon nanotubes are 2% and 1% of the total mass of capric acid, lauric acid and polyethylene glycol, respectively;

[0100] Step 2: After mixing hydroxyethyl methacrylate, glycidyl methacrylate, and deionized water, potassium persulfate and sodium dodecylbenzenesulfonate were added, and the reaction was carried out under nitrogen protection at a temperature of 70° C. and a stirring speed of 300 rpm for 2 hours to obtain a shell material prepolymer solution, wherein the mass ratio of hydroxyethyl methacrylate, glycidyl methacrylate, and deionized water was 65:25:400, and the addition amounts of potassium persulfate and sodium dodecylbenzenesulfonate were 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 material prepolymer solution, perform high-speed shearing at 70°C and a shear speed of 5000 rpm for 20 minutes, add N,N'-methylenebisacrylamide, continue to react at 70°C for 1 hour, centrifuge at a centrifugal speed of 8000 rpm, wash, and dry to obtain phase change microcapsules, wherein the mass ratio of the core material to the shell material 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 comprises the following steps:

[0103] Add a dispersion stabilizer and a composite flame retardant to deionized water, stir at 30°C with a stirring speed of 500 rpm for 20 minutes, reduce the stirring speed to 100 rpm, add a surfactant, continue stirring for 10 minutes, increase the temperature to 40°C, add a free radical scavenger, and stir for 20 minutes. Finally, reduce the stirring speed to 50 rpm, add phase change microcapsules, stir for 30 minutes, and homogenize twice at a homogenization pressure of 20 MPa 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 a composite flame retardant, 10 parts of phase change microcapsules, 10 parts of a free radical scavenger, 3 parts of a surfactant, 3 parts of a dispersion 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 lauryl sulfate, and the dispersion stabilizer is sodium polyacrylate.

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

[0107] Step 1, capric acid, lauric acid and polyethylene glycol are mixed, heated to 80°C, melt-blended, and nano-silica and carbon nanotubes are added. The mixture is stirred at a stirring speed of 300 rpm for 30 minutes to obtain a core material, wherein the mass ratio of capric acid, lauric acid and polyethylene glycol is 4:2:5, the polyethylene glycol is composed of PEG6000 and PEG2000 with a mass ratio of 10:3, and the added amounts of nano-silica and carbon nanotubes are 2% and 1% of the total mass of capric acid, lauric acid and polyethylene glycol, respectively;

[0108] Step 2: After mixing hydroxyethyl methacrylate, methacrylamide, and deionized water, potassium persulfate and sodium dodecylbenzenesulfonate were added, and the mixture was stirred at 70° C. and 300 rpm under nitrogen protection for 2 hours to obtain a shell material prepolymer solution, wherein the mass ratio of hydroxyethyl methacrylate, methacrylamide, and deionized water was 70:20:400, and the addition amounts of potassium persulfate and sodium dodecylbenzenesulfonate were 0.5% and 1% of the total mass of hydroxyethyl methacrylate and methacrylamide, respectively;

[0109] Step 3: Add the core material to the shell material prepolymer solution, perform high-speed shearing at 70°C and a shear speed of 5000 rpm for 20 minutes, add N,N'-methylenebisacrylamide, continue to react at 70°C for 1 hour, centrifuge at a centrifugal speed of 8000 rpm, wash, and dry to obtain phase change microcapsules, wherein the mass ratio of the core material to the shell material 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 comprises the following steps:

[0111] Add a dispersion stabilizer and a composite flame retardant to deionized water, stir at 30°C with a stirring speed of 500 rpm for 20 minutes, reduce the stirring speed to 100 rpm, add a surfactant, continue stirring for 10 minutes, increase the temperature to 40°C, add a free radical scavenger, and stir for 20 minutes. Finally, reduce the stirring speed to 50 rpm, add phase change microcapsules, stir for 30 minutes, and homogenize twice at a homogenization pressure of 20 MPa 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 the present application are as follows:

[0114] A 256650 cylindrical battery pack with four thermocouples connected to its surface was continuously heated to cause thermal runaway. When the lithium battery exploded and violent flames occurred, the fire extinguishing additives prepared in Examples 1-3 and Comparative Examples 1-7 were quickly activated to spray the fire extinguishing additives. The fire extinguishing time, the amount of fire extinguishing additive used, the cooling rate, and the maximum surface temperature of the lithium-ion battery after fire extinguishing were recorded. The lithium battery was also observed for re-ignition.

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

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

[0117]

[0118] As can be seen from Table 1, the fire extinguishing additive for lithium-ion batteries prepared in the present application has the advantages of small amount of fire extinguishing agent, fast fire extinguishing speed, can extinguish the flame in a short time, high cooling rate, can quickly reduce the fire scene temperature of the lithium-ion battery, and no re-ignition phenomenon, eliminating fire hazards, providing strong support for fire fighting work, and protecting people's lives and property safety.

[0119] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make non-creative modifications to the present embodiment as needed, but as long as they are within the scope of the claims of the present application, they are protected by the patent law.

Claims

1. A fire extinguishing additive for lithium batteries, characterized in that: The invention 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 scavengers, 3-6 parts of surfactants, 3-5 parts of dispersion stabilizers and 70-100 parts of deionized water.

2. The fire extinguishing additive for lithium batteries according to claim 1, characterized in that: The composite flame retardant consists of trimethyl phosphate, melamine cyanurate and barium metaborate in a mass ratio of 5-8:2-3:1-2.

3. The fire extinguishing additive for lithium batteries according to claim 1, characterized in that: The preparation of the phase-change microcapsules includes the following steps: Step 1: capric acid, lauric acid and polyethylene glycol are mixed, heated to 80-85° C., melt-blended, and nano-silica and carbon nanotubes are added, and stirred at a stirring speed of 300-500 rpm for 30-40 minutes to obtain a core material; Step 2: After mixing hydroxyethyl methacrylate, methacrylamide, glycidyl methacrylate and deionized water, potassium persulfate and sodium dodecylbenzenesulfonate are added, and the reaction temperature is 70-80° C. under nitrogen protection, and the reaction is stirred for 2-3 hours to obtain a shell material prepolymer solution; Step 3: Add the core material to the shell material prepolymer solution, high-speed shear for 20-30 min at 70-80°C and a shear speed of 5000-8000 rpm, add N,N'-methylenebisacrylamide, continue the reaction at 70-75°C for 1-3 h, centrifuge, wash, and dry to obtain phase change microcapsules.

4. The fire extinguishing additive for lithium batteries according to claim 3, characterized in that: In the step 1, the mass ratio of capric 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 capric acid, lauric acid and polyethylene glycol, respectively.

5. The fire extinguishing additive for lithium batteries according to claim 3, characterized in that: 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 added amounts of potassium persulfate and sodium dodecylbenzenesulfonate are 0.5-2% and 1-3% of the total mass of hydroxyethyl methacrylate, methacrylamide and glycidyl methacrylate, respectively.

6. The fire extinguishing additive for lithium batteries according to claim 3, characterized in that: In step 3, the mass ratio of the core material and the 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.

7. 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-oxyl.

8. The fire extinguishing additive for lithium batteries according to claim 1, characterized in that: The surfactant is one or more of sodium lauryl sulfate, fatty alcohol polyoxyethylene ether, and polysorbate; the dispersion stabilizer is one or more of polyvinyl pyrrolidone, sodium polyacrylate, and gum arabic.

9. A method for preparing a fire extinguishing additive for lithium batteries according to any one of claims 1 to 8, characterized in that: The following steps are involved: Add a dispersion stabilizer and a composite flame retardant to deionized water, stir at 30-40°C with a stirring speed of 500-600 rpm for 20-30 minutes, reduce the stirring speed to 100-200 rpm, add a surfactant, continue stirring for 10-20 minutes, increase the temperature to 40-50°C, add a free radical scavenger, stir for 20-40 minutes, finally reduce the stirring speed to 50-100 rpm, add phase change microcapsules, stir for 30-40 minutes, and after homogenization, obtain a fire extinguishing additive for lithium batteries.

10. The method for preparing a fire extinguishing additive for lithium batteries according to claim 9, characterized in that: The homogenization pressure is 20-30 MPa, and the homogenization times are 2-3 times.

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