Cooling liquid for immersion liquid-cooled battery and preparation method thereof

Abstract

The present invention relates to the field of battery thermal management technology, specifically disclosing a coolant for an immersed liquid-cooled battery and a preparation method thereof. The coolant comprises the following components by mass percentage: 50-70% modified silicone oil; 20-40% hydrocarbon; and 0.9-11% additive. The modified silicone oil is vinyl-terminated silicone oil or amino-modified silicone oil, and the hydrocarbon is an isoparaffin or cycloparaffin. The present invention optimizes the formula to obtain a coolant for an immersed liquid-cooled battery, which is composed mainly of modified silicone oil and hydrocarbon, and contains additives such as nano-thermal conductive materials, corrosion inhibitors, antioxidants, and defoaming agents. The coolant has the advantages of high safety, efficient heat dissipation, biocompatibility, and adaptability to a wide temperature range, effectively improving the heat dissipation efficiency of the battery and ensuring the stability and safety of the liquid cooling system.

Description

Technical Field

[0001] The present invention relates to the technical field of battery thermal management, and in particular to a coolant for an immersion liquid-cooled battery and a preparation method thereof. Background Art

[0002] New energy storage systems, primarily based on lithium-ion and sodium-ion batteries, are essential equipment foundations and key supporting technologies for building new power systems and promoting green and low-carbon energy transformation. Thermal management technology is a crucial component of energy storage systems and a guarantee for safe battery operation. Currently, the more mature thermal management approaches for energy storage are air cooling and liquid cooling. Air cooling offers poor heat dissipation in large, high-power energy storage systems, while liquid cooling offers greater cooling efficiency and space utilization, making it suitable for highly integrated, large-scale energy storage. Immersed liquid cooling uses a highly conductive and insulating liquid as a cooling medium, removing heat generated by the battery through convection. This results in a higher heat transfer coefficient, faster cooling, and better temperature uniformity. The battery pack is completely isolated from the air, allowing for timely heat dissipation and blocking of the battery assembly's combustion medium in the event of thermal runaway in some cells, preventing open flames and explosions and reducing the potential for accidents.

[0003] The key to immersion liquid cooling technology is the coolant, which is primarily categorized as single-phase or two-phase. Single-phase coolants (such as mineral insulating oil, silicone oil, and single-phase fluorinated fluid) transfer heat through sensible heat, possessing high specific heat capacity and stability, but with relatively limited heat dissipation efficiency. Two-phase coolants (such as two-phase fluorinated fluid, liquid propane, and synthetic hydrocarbons) undergo phase change upon absorbing heat, transferring large amounts of heat through latent heat. This results in high heat dissipation efficiency, but places high demands on system pressure control and sealing, and some coolants exhibit poor chemical stability. A Chinese patent (publication number CN113861948A) proposes a coolant and preparation method. The coolant primarily comprises: 20-40 parts mineral oil defoamer; 1-5 parts oily epoxy resin; 0.01-0.1 parts BYK-R605 dispersant; 5-10 parts siloxane; 0.03-0.08 parts flash point enhancer; and 0.02-0.06 parts hydroxyl-terminated polybutadiene. Liquid immersion cooling coolant for data centers.

[0004] A Chinese patent (publication number CN115873565A) proposes a lithium-ion battery immersion coolant composed of propylene glycol, perfluorohexanone, dipropylene glycol methyl ether, a defoamer, a corrosion inhibitor, and 2,6-di-tert-butyl-p-cresol. The coolant exhibits excellent antifreeze, heat transfer, insulation, and low-temperature fluidity, making it suitable for immersion cooling systems in new energy vehicles and energy storage power plants. However, the coolant's primary component is fluorine-containing substances, the decomposition of which can be harmful to humans and the environment.

[0005] Immersion cooling technology, using electronic fluorinated liquid as a cooling medium, has demonstrated excellent cooling effectiveness in data centers. However, the high cost of fluorinated liquids limits their widespread use. Batteries containing mineral oil are flammable and pose a risk of thermal runaway. Some immersion cooling fluids have poor material compatibility and low thermal conductivity, making them incapable of meeting the heat dissipation requirements of high-power batteries. Therefore, developing a coolant for immersion-cooled batteries is crucial for improving the performance of immersion-cooled battery systems. Summary of the Invention

[0006] In view of the above shortcomings, the present invention provides a coolant for immersion liquid-cooled batteries. The coolant has the characteristics of high safety, efficient heat dissipation, and biocompatibility. The specific technical solution is as follows:

[0007] A coolant for an immersion-type liquid-cooled battery, comprising the following components in percentage by mass:

[0008] Modified silicone oil: 50-70%;

[0009] Hydrocarbons: 20-40%;

[0010] Additives: 0.9-11%;

[0011] The modified silicone oil is vinyl-terminated silicone oil or amino-modified silicone oil, and the hydrocarbon is isoparaffin or cycloparaffin.

[0012] Preferably, in the above-mentioned coolant for immersed liquid-cooled batteries, based on the total mass of the coolant, the mass percentage composition of the additives is: 0.5-5% nano-thermal conductive particles, 0.3-2% corrosion inhibitor, 0.1-2% antioxidant, 0.01-1% defoaming agent, and 0.05-1% pH regulator.

[0013] Preferably, in the above-mentioned coolant for submerged liquid-cooled batteries, the isoparaffin is Isopar L or Shellsol D100, and the cycloparaffin is decahydronaphthalene, methylcyclohexane or bromocyclohexane.

[0014] Preferably, in the above-mentioned coolant for immersion liquid-cooled batteries, the thermally conductive nanoparticles are graphene, carbon nanotubes, boron nitride or aluminum oxide nanoparticles, and the particle size of the thermally conductive nanoparticles is ≤100 nm.

[0015] Preferably, in the above-mentioned coolant for immersed liquid-cooled batteries, the corrosion inhibitor is benzotriazole or isooctanoic acid, and the antioxidant is di-tert-butyl-p-cresol.

[0016] Preferably, in the above-mentioned coolant for immersion-type liquid-cooled batteries, the viscosity of the modified silicone oil is 20-500 cSt.

[0017] Preferably, in the above-mentioned coolant for immersed liquid-cooled batteries, the defoaming agent is polyether-modified silicone oil, and the pH regulator is potassium hydroxide.

[0018] Preferably, in the coolant for the submerged liquid-cooled battery, the vinyl-terminated silicone oil is prepared by the following method: adding octamethylcyclotetrasiloxane and tetramethyldivinyldisiloxane to a reaction kettle equipped with a stirrer, a thermometer and a reflux condenser, wherein the amount of tetramethyldivinyldisiloxane is 0.5-2% of the mass of octamethylcyclotetrasiloxane;

[0019] Then, under stirring, concentrated sulfuric acid catalyst is slowly added, wherein the catalyst amount is 0.1% to 1% of the mass of octamethylcyclotetrasiloxane, the reaction temperature is controlled at 80 to 120° C., and stirring is continued at 400 to 600 rpm for 4 to 6 hours. After the reaction is cooled to room temperature, an appropriate amount of sodium bicarbonate is added to neutralize the catalyst, and then low-boiling point by-products and unreacted raw materials are removed by vacuum distillation. Finally, the product is filtered to remove solid impurities to obtain a colorless and transparent vinyl-terminated silicone oil.

[0020] Preparation of the amino-modified silicone oil: octamethylcyclotetrasiloxane and N-β-aminoethyl-γ-aminopropylmethyldimethoxysilane are added to a reaction kettle equipped with a stirrer, a thermometer, and a reflux condenser, wherein the amount of N-β-aminoethyl-γ-aminopropylmethyldimethoxysilane is 0.5-2% of the mass of octamethylcyclotetrasiloxane;

[0021] Then, under stirring, potassium hydroxide catalyst is slowly added, wherein the amount of the catalyst is 0.1% to 1% of the mass of octamethylcyclotetrasiloxane, the reaction temperature is controlled at 80 to 120° C., and stirring is continued at 400 to 600 rpm for 4 to 6 hours. After the reaction is cooled to room temperature, an appropriate amount of acetic acid is added to neutralize the catalyst, and then reduced pressure distillation is performed to remove low-boiling point byproducts and unreacted raw materials. Finally, the product is filtered to remove solid impurities to obtain amino silicone oil.

[0022] On the other hand, the present invention also provides a method for preparing the above-mentioned coolant for the immersion liquid-cooled battery, comprising the following steps:

[0023] (1) Add modified silicone oil and hydrocarbon into the reactor in proportion and stir evenly to obtain the base liquid;

[0024] (2) Adding the nano-thermal conductive particles to the base liquid obtained in step (1), and using ultrasonic dispersion with an ultrasonic power of 200-400W and an ultrasonic time of 60-90min to form a stable suspension;

[0025] (3) adding a corrosion inhibitor, an antioxidant, and a defoaming agent to the stable suspension obtained in step (2) in sequence, stirring the mixture to obtain a mixed solution, and filtering the mixture to obtain a coolant;

[0026] (4) The pH value of the mixed solution is adjusted to 7.2-8.0 using a pH regulator, and filtered to obtain a coolant for an immersion liquid-cooled battery.

[0027] Preferably, in the above preparation method, in step (1), the stirring speed is 500-800 r / min, and the stirring time is 30-60 minutes; in step (3), the stirring speed is 300-500 r / min, and the stirring time is 30-45 minutes.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] 1. In the present invention, by optimizing the formula, a coolant for immersion-type liquid-cooled batteries is obtained, which is composed of modified silicone oil and hydrocarbons as the main coolant, and additives such as nano-thermal conductive materials, corrosion inhibitors, antioxidants and defoaming agents. It has the advantages of high safety, efficient heat dissipation, material compatibility and adaptability to a wide temperature range, effectively improving the heat dissipation efficiency of the battery and ensuring the stability and safety of the liquid cooling system.

[0030] 2. The coolant for submerged liquid-cooled batteries of the present invention enhances the thermal conductivity of the coolant system by adding modified silicone oil and hydrocarbons, reduces the viscosity of the coolant system, adds nano-thermal conductive materials to increase the thermal conductivity of the coolant, further improving the thermal conductivity of the coolant, and adds corrosion inhibitors, antioxidants, and defoaming agents to improve the stability of the coolant. DETAILED DESCRIPTION

[0031] The specific embodiments of the present invention are described in detail below, but it should be understood that the scope of protection of the present invention is not limited by the specific embodiments. Unless otherwise defined, all technical terms used hereinafter have the same meaning as those generally understood by those skilled in the art. The technical terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the scope of protection of the present invention. Unless otherwise specified, the various raw materials, reagents, instruments and equipment used in the present invention can be purchased from the market or can be prepared by existing methods.

[0032] The vinyl-terminated silicone oil and amino-modified silicone oil used in the following examples and comparative examples were prepared by the following preparation methods.

[0033] The preparation method of vinyl-terminated silicone oil comprises the following steps: adding octamethylcyclotetrasiloxane and tetramethyldivinyldisiloxane into a reaction kettle equipped with a stirrer, a thermometer and a reflux condenser, wherein the amount of tetramethyldivinyldisiloxane used is 1.5% of the mass of octamethylcyclotetrasiloxane;

[0034] Then, under stirring, concentrated sulfuric acid catalyst is slowly added, the catalyst dosage is 0.3% of the mass of octamethylcyclotetrasiloxane, the reaction temperature is controlled at 100°C, and stirring is continued at 500 rpm for 5 hours. After the reaction is cooled to room temperature, an appropriate amount of sodium bicarbonate is added to neutralize the catalyst, followed by reduced pressure distillation to remove low-boiling point by-products and unreacted raw materials. Finally, the product is filtered to remove solid impurities to obtain colorless and transparent vinyl-terminated silicone oil.

[0035] The preparation method of amino-modified silicone oil comprises the following steps: adding octamethylcyclotetrasiloxane and N-β-aminoethyl-γ-aminopropylmethyldimethoxysilane into a reaction kettle equipped with a stirrer, a thermometer and a reflux condenser, wherein the amount of N-β-aminoethyl-γ-aminopropylmethyldimethoxysilane used is 1.5% of the mass of octamethylcyclotetrasiloxane;

[0036] Then, under stirring, potassium hydroxide catalyst is slowly added, the catalyst amount is 0.3% of the mass of octamethylcyclotetrasiloxane, the reaction temperature is controlled at 100°C, and stirring is continued at 500 rpm for 5 hours. When the reaction is cooled to room temperature, an appropriate amount of acetic acid is added to neutralize the catalyst, and low-boiling point by-products and unreacted raw materials are optionally distilled under reduced pressure. Finally, the product is filtered to remove solid impurities to obtain amino silicone oil.

[0037] Battery pack specifications and test conditions are as follows:

[0038] (1) Battery specifications: 18650 ternary lithium-ion batteries from the same batch are used to form a 10S2P module with a capacity of 10Ah, an initial SOC of 50%, and an initial temperature of 25°C.

[0039] (2) Charge and discharge parameters: 3C constant current charging to 4.2V, then constant voltage charging until the current drops to 0.1C; 2C constant current discharge to 2.75V; let stand for 15 minutes between each cycle.

[0040] Example 1

[0041] A coolant for an immersed liquid-cooled battery is composed of the following components in percentage by mass: 60% vinyl-terminated silicone oil, 35% Shellsol D100, 2.5% graphene, 1.3% benzotriazole, 0.8% di-tert-butyl-p-cresol, 0.25% polyether-modified silicone oil, and 0.15% potassium hydroxide.

[0042] A method for preparing a coolant for an immersion liquid-cooled battery comprises the following steps:

[0043] (1) Add modified silicone oil and hydrocarbon into the reactor in proportion, stir evenly, rotate at 600 r / min, and stir for 40 min to obtain the base liquid;

[0044] (2) Add the nano-thermal conductive particles into the base liquid and use ultrasonic dispersion with an ultrasonic power of 300 W and an ultrasonic time of 80 min to form a stable suspension;

[0045] (3) Add corrosion inhibitor, antioxidant and defoaming agent to the stable suspension in sequence, stir and dissolve, stir at a speed of 400 r / min, and stir for 40 min; add pH regulator to adjust the pH value of the coolant, filter through a 0.22 μm polytetrafluoroethylene filter membrane to obtain the coolant for immersion liquid-cooled batteries, and then fill and seal for storage.

[0046] The thermal conductivity of the coolant in this embodiment is 0.38 W (m·K) -1 (25°C), which is about 40% higher than traditional silicone oil; in the energy storage battery test, the maximum temperature of the battery pack was 43°C, and the cycle life was increased by 33% compared with the battery cells without liquid cooling; the coolant has good safety and no risk of combustion or explosion.

[0047] Example 2

[0048] A coolant for an immersed liquid-cooled battery is composed of the following components in percentage by mass: 56% vinyl-terminated silicone oil, 40% Shellsol D100, 2.2% carbon nanotubes, 0.8% isooctanoic acid, 0.2% di-tert-butyl-p-cresol, 0.3% polyether-modified silicone oil, and 0.5% potassium hydroxide.

[0049] The preparation method of the coolant for the immersion liquid-cooled battery in this embodiment is the same as that in Example 1.

[0050] In this embodiment, the viscosity of the coolant is 8.5 cSt (25°C), the flow resistance is reduced by 30%, and it remains liquid at -50°C. The maximum temperature of the battery pack is 45°C, and the cycle life is increased by 25% compared to batteries without liquid cooling.

[0051] Example 3

[0052] A coolant for an immersed liquid-cooled battery is composed of the following components in percentage by mass: 56% amino-modified silicone oil, 40% methylcyclohexane, 2.4% aluminum oxide nanoparticles, 0.5% benzotriazole, 0.4% di-tert-butyl-p-cresol, 0.2% polyether-modified silicone oil, and 0.5% potassium hydroxide.

[0053] The preparation method of the coolant for the immersion liquid-cooled battery in this embodiment is the same as that in Example 1.

[0054] The thermal conductivity of the coolant in this embodiment is 0.36 W (m·K) -1 (25℃), a 500-hour immersion test on the aluminum sheet found no obvious corrosion, and after aging at 150℃ for 500 hours, the acid value increased by 0.02 mgKOH / g.

[0055] Example 4

[0056] A coolant for an immersed liquid-cooled battery is composed of the following components in percentage by mass: 65% amino-modified silicone oil, 30% methylcyclohexane, 2% graphene, 1.3% isooctanoic acid, 1% di-tert-butyl-p-cresol, 0.5% polyether-modified silicone oil, and 0.2% potassium hydroxide.

[0057] The preparation method of the coolant for the immersion liquid-cooled battery in this embodiment is the same as that in Example 1.

[0058] The viscosity of the coolant in this embodiment is 9 cSt (25°C), the maximum temperature of the battery pack is 46°C, the cycle life is increased by 22% compared with the battery cells without liquid cooling, and the biodegradation rate reaches 88%.

[0059] Example 5

[0060] A coolant for an immersed liquid-cooled battery is composed of the following components in percentage by mass: 60% amino-modified silicone oil, 36% methylcyclohexane, 1.8% carbon nanotubes, 1% benzotriazole, 0.8% di-tert-butyl-p-cresol, 0.2% polyether-modified silicone oil, and 0.2% potassium hydroxide.

[0061] The steps for preparing the coolant for the submerged liquid-cooled battery in this embodiment are the same as those in Example 1.

[0062] The thermal conductivity of the coolant in Example 5 is 0.35 W (m·K) -1 (25℃), at -40℃, the coolant can still flow normally, has good fluidity, and the flash point is 210℃.

[0063] Example 6:

[0064] A coolant for an immersed liquid-cooled battery is composed of the following components in percentage by mass: 72% vinyl-terminated silicone oil, 25% methylcyclohexane, 1.25% aluminum oxide nanoparticles, 0.4% isooctanoic acid, 1% di-tert-butyl-p-cresol, 0.2% polyether-modified silicone oil, and 0.15% potassium hydroxide.

[0065] The steps for preparing the coolant for the submerged liquid-cooled battery in this embodiment are the same as those in Example 1.

[0066] In this embodiment, the maximum temperature of the battery pack in the coolant is 47°C, and the cycle life is improved by 18% compared with the battery cells without liquid cooling. The copper sheet was immersed in a 500-hour test and no obvious corrosion was observed. The acid value remained basically unchanged after aging at 120°C for 800 hours.

[0067] Example 7

[0068] A coolant for an immersed liquid-cooled battery is composed of the following components in percentage by mass: 62% vinyl-terminated silicone oil, 36% methylcyclohexane, 1% benzotriazole, 0.5% di-tert-butyl-p-cresol, 0.3% polyether-modified silicone oil, and 0.2% potassium hydroxide.

[0069] The thermal conductivity of the coolant in this embodiment is 0.25 W (m·K) -1 (25℃), the maximum temperature of the battery pack is 47.5℃, and the cycle life is increased by 15% compared with the battery cells without liquid cooling.

[0070] Comparative Example 1

[0071] A coolant for an immersed liquid-cooled battery is composed of the following components in percentage by mass: 93% methyl silicone oil, 2% benzotriazole, 2.5% di-tert-butyl-p-cresol, 2% polyether-modified silicone oil, and 0.5% potassium hydroxide.

[0072] The thermal conductivity of the coolant in this comparative example is 0.13 W (m·K) -1 (25°C), which is significantly lower than the coolant of the present invention. The maximum temperature of the battery pack is 52°C, and the cycle life is increased by 8% compared with the battery cells without liquid cooling. The aluminum sheet was immersed in a 500-hour test, and the corrosion rate was 0.05mm / year. The flash point was 150°C, and there was a risk of combustion.

[0073] Comparative Example 2

[0074] This comparative example differs from the example in that vinyl-terminated silicone oil is used instead of Shellsol D100, and the rest is the same as in Example 1.

[0075] The performance of the examples and comparative examples was tested, and the biodegradation rate was tested according to the closed respirometer method of standard GB / T 22047. The performance data are shown in Table 1.

[0076] Table 1 Coolant performance data of Examples and Comparative Examples

[0077] Thermal conductivity W / (m·K)25℃ Viscosity cSt25℃ Heat dissipation efficiency (maximum battery pack temperature) Compatibility (corrosion) Antioxidant properties (acid value) Biodegradation rate (%) Adaptability to extreme environments Safety flash point / ℃ Cycle life improvement ratio (%) Example 1 0.38 9.2 43℃ No obvious corrosion Aging at 150℃ for 500 hours increases the acid value by 0.03mgKOH / g 86 The fluidity becomes worse at -45℃ ≥300, no risk of combustion or explosion 33 Example 2 0.33 8.5 45℃ The corrosion rate of aluminum sheets is 0.002mm / year Aging at 120℃ for 800 hours: acid value increases by 0.02mgKOH / g 85 Remains liquid at -50℃ ≥300, no risk of combustion or explosion 25 Example 3 0.36 10.1 44℃ A 500-hour immersion test on aluminum sheets revealed no significant corrosion Aging at 150℃ for 500 hours increases the acid value by 0.02mgKOH / g 87 The coolant can still flow normally at -40℃ ≥300, no risk of combustion or explosion 28 Example 4 0.34 9 46℃ The copper sheet was immersed in water for 1000 hours and the corrosion rate was 0.0015 mm / year. Aging at 130℃ for 700 hours: acid value increases by 0.04mgKOH / g 88 Coolant can work normally at -40℃ ≥300, no risk of combustion or explosion 22 Example 5 0.35 8.8 45.5℃ No obvious corrosion Aging at 140℃ for 600 hours: acid value increases by 0.03mgKOH / g 86 Can flow normally at -40℃ ≥300, no risk of combustion or explosion 23 Example 6 0.32 10.5 47℃ No obvious corrosion to copper sheets Acid value remains basically unchanged after aging for 800 hours at 120℃ 84 At -48℃, the coolant becomes slightly thicker but does not affect the flow ≥300, no risk of combustion or explosion 18 Example 7 0.25 9.5 47.5℃ Slightly corrodes aluminum sheets, with a corrosion rate of 0.01 mm / year Aging at 150℃ for 500 hours increases the acid value by 0.08mgKOH / g 80 The fluidity is significantly reduced at -40℃ ≥300, no risk of combustion or explosion 15 Comparative Example 1 0.13 11.8 52℃ The corrosion rate of aluminum sheets is 0.05 mm / year Aging at 100℃ for 300 hours: acid value increases by 0.2mgKOH / g 15 Solidifies at -30℃ and evaporates at 45℃ 150, there is a risk of burning 8 Comparative Example 2 0.30 12.5 55℃ There is no obvious corrosion to the copper sheet, and a slight oxide film appears on the surface of the aluminum sheet Aging at 150℃ for 500 hours increases the acid value by 0.06mgKOH / g 70 The fluidity is significantly reduced at -40℃ 210, no risk of combustion or explosion 5

[0078] The foregoing descriptions of specific exemplary embodiments of the present invention are for purposes of illustration and description. These descriptions are not intended to limit the invention to the precise forms disclosed, and it is apparent that many variations and modifications are possible in light of the foregoing teachings. The exemplary embodiments have been selected and described for the purpose of explaining the specific principles of the invention and their practical application, thereby enabling those skilled in the art to realize and utilize a variety of exemplary embodiments of the invention and various options and modifications. The scope of the invention is intended to be defined by the claims and their equivalents.

Claims

1. A coolant for an immersion liquid-cooled battery, characterized in that: The following components are included in mass percentage: Modified silicone oil: 50-70%; Hydrocarbons: 20-40%; Additives: 0.9-11%; The modified silicone oil is vinyl-terminated silicone oil or amino-modified silicone oil, and the hydrocarbon is Shellsol D100 or methylcyclohexane.

2. The coolant for immersion-type liquid-cooled batteries according to claim 1, characterized in that: Based on the total mass of the coolant, the mass percentage composition of the additives is: 0.5-5% nano thermal conductive particles, 0.3-2% corrosion inhibitor, 0.1-2% antioxidant, 0.01-1% defoaming agent, and 0.05-1% pH regulator.

3. The coolant for immersion-type liquid-cooled batteries according to claim 2, characterized in that: The nano thermally conductive particles are graphene, carbon nanotubes, boron nitride or aluminum oxide nanoparticles, and the particle size of the nano thermally conductive particles is ≤100 nm.

4. The coolant for immersion-type liquid-cooled batteries according to claim 2, characterized in that: The corrosion inhibitor is benzotriazole or isooctanoic acid, and the antioxidant is di-tert-butyl-p-cresol.

5. The coolant for immersion-type liquid-cooled batteries according to claim 1, characterized in that: The viscosity of the modified silicone oil is 20-500 cSt.

6. The coolant for immersion-type liquid-cooled batteries according to claim 2, characterized in that: The defoaming agent is polyether modified silicone oil, and the pH regulator is potassium hydroxide.

7. The coolant for immersion-type liquid-cooled batteries according to claim 1, characterized in that: The vinyl-terminated silicone oil is prepared by the following method: adding octamethylcyclotetrasiloxane and tetramethyldivinyldisiloxane into a reaction kettle equipped with a stirrer, a thermometer and a reflux condenser, wherein the amount of tetramethyldivinyldisiloxane used is 0.5-2% of the mass of octamethylcyclotetrasiloxane; Then, under stirring, concentrated sulfuric acid catalyst is slowly added, the catalyst amount being 0.1% to 1% of the mass of octamethylcyclotetrasiloxane, the reaction temperature is controlled at 80 to 120° C., and stirring is continued at 400 to 600 rpm for 4 to 6 hours. After the reaction is cooled to room temperature, an appropriate amount of sodium bicarbonate is added to neutralize the catalyst, followed by vacuum distillation to remove low-boiling point byproducts and unreacted raw materials. Finally, the product is filtered to remove solid impurities to obtain a colorless and transparent vinyl-terminated silicone oil; Preparation of the amino-modified silicone oil: octamethylcyclotetrasiloxane and N-β-aminoethyl-γ-aminopropylmethyldimethoxysilane are added to a reaction kettle equipped with a stirrer, a thermometer, and a reflux condenser, wherein the amount of N-β-aminoethyl-γ-aminopropylmethyldimethoxysilane is 0.5-2% of the mass of octamethylcyclotetrasiloxane; Then, under stirring, potassium hydroxide catalyst is slowly added, wherein the amount of the catalyst is 0.1% to 1% of the mass of octamethylcyclotetrasiloxane, the reaction temperature is controlled at 80 to 120° C., and stirring is continued at 400 to 600 rpm for 4 to 6 hours. After the reaction is cooled to room temperature, an appropriate amount of acetic acid is added to neutralize the catalyst, and then reduced pressure distillation is performed to remove low-boiling point byproducts and unreacted raw materials. Finally, the product is filtered to remove solid impurities to obtain amino silicone oil.

8. A method for preparing a coolant for an immersion-type liquid-cooled battery according to any one of claims 1 to 7, characterized in that: The following steps are involved: (1) Add modified silicone oil and hydrocarbon into the reactor in proportion and stir evenly to obtain the base liquid; (2) Adding the nano-thermal conductive particles to the base liquid obtained in step (1), and using ultrasonic dispersion with an ultrasonic power of 200-400W and an ultrasonic time of 60-90min to form a stable suspension; (3) adding a corrosion inhibitor, an antioxidant, and a defoaming agent to the stable suspension obtained in step (2) in sequence, stirring the mixture to obtain a mixed solution, and filtering the mixture to obtain a coolant; (4) The pH value of the mixed solution is adjusted to 7.2-8.0 using a pH regulator, and filtered to obtain a coolant for an immersion liquid-cooled battery.

9. The preparation method according to claim 8, characterized in that In the step (1), the stirring speed is 500-800 r / min, and the stirring time is 30-60 min; in the step (3), the stirring speed is 300-500 r / min, and the stirring time is 30-45 min.