Lithium battery immersed coolant containing surface modified aluminum oxide nanoparticles

Abstract

The invention relates to the technical field of lithium battery immersed coolants, in particular to a lithium battery immersed coolant containing surface modified aluminum oxide nanoparticles. The coolant comprises the following components in percentage by mass: 60%-90% of a pentaerythritol ester matrix, 0.5%-5% of surface modified Al2O3 nanoparticles, 0.1%-1% of a silane coupling agent modifier, 0.1%-0.5% of an auxiliary stabilizer and 3.5%-39.3% of absolute ethyl alcohol.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of lithium battery immersion coolant, in particular to a lithium battery immersion coolant containing surface-modified alumina nanoparticles. BACKGROUND

[0002] With the rapid development of new energy vehicles and energy storage technology, lithium batteries have become the core power source due to their high energy density and long cycle life. However, a large amount of heat is generated during the charging and discharging process of lithium batteries, which will lead to an increase in battery temperature and a decrease in consistency, and even cause safety accidents such as thermal runaway. Therefore, an efficient thermal management system is crucial. In the case of high-rate charging and discharging or high ambient temperature, the internal temperature of traditional power batteries tends to rise rapidly, which will lead to a decrease in battery performance, a reduction in service life, and even a thermal runaway hazard. Immersion cooling achieves direct heat exchange by completely immersing the battery pack in an insulating coolant.

[0003] Immersion cooling technology has become an important development direction for lithium battery thermal management due to its full contact with the battery surface and high heat exchange efficiency. The performance of the coolant directly determines the application effect of the technology. However, the existing immersion coolants have the following shortcomings: Traditional immersion coolants, such as mineral oil and No. 10 transformer oil, have a flash point lower than the requirement of IEC 60199-2010 insulating oil (above 250℃), which can easily cause a fire at high temperatures. They are all derived from fossil energy, which is non-renewable and difficult to biodegrade, and have poor environmental friendliness.

[0004] Fluorinated liquids, such as Novec series, are high in cost and non-renewable, and the high density inevitably increases the weight of the cooling system.

[0005] Water-based coolants, such as water-glycol mixtures, can accelerate acidification and exacerbate corrosion of carbon steel, copper and other metals when used for a long time.

[0006] In summary, the existing immersion coolants have low thermal conductivity, poor chemical stability and low environmental compatibility. SUMMARY

[0007] One of the purposes of the present application is to provide a lithium battery immersion coolant containing surface-modified alumina nanoparticles, which can balance high thermal conductivity, excellent chemical stability and environmental compatibility to meet the stringent requirements of electric vehicles, energy storage systems and other battery thermal management.

[0008] In order to achieve the above-mentioned purpose, a lithium battery immersion coolant containing surface-modified alumina nanoparticles is provided, the coolant comprising the following mass percentage composition: 60%-90% pentaerythritol ester base, 0.5%-5% surface-modified Al2O3 nanoparticles, 0.1%-1% silane coupling agent modifier, 0.1%-0.5% auxiliary stabilizer, and 3.5%-39.3% anhydrous ethanol.

[0009] Further, the particle size of the surface-modified Al2O3 nanoparticles is 20-100 nm.

[0010] Further, the particle size of the surface-modified Al2O3 nanoparticles is 50 nm.

[0011] Further, the silane coupling agent modifier is γ-methacryloyloxypropyltrimethoxysilane or γ-aminopropyltriethoxysilane.

[0012] Further, the auxiliary stabilizer is vitamin E acetate or lecithin.

[0013] Further, the preparation method of the coolant comprises the following steps: Step one, add Al2O3 nanoparticles to anhydrous ethanol and ultrasonically disperse for 30 min; add a silane coupling agent modifier, magnetically stir at 60-80°C for 2 h to form a lipophilic surface; centrifuge, wash, and vacuum dry to obtain modified particles; Step two, add the modified particles and auxiliary stabilizer to pentaerythritol ester in proportion, pre-disperse, and then ultrasonically treat to form a homogeneous stable system, thereby completing the preparation of the coolant sample.

[0014] Beneficial effects: In this scheme, the Al2O3 nanoparticles are surface-modified by a silane coupling agent, which forms a stable chemical bonding interface between the nanoparticles and the pentaerythritol ester base. This interface is of great significance, as it can effectively reduce the interfacial thermal resistance, like building a high-efficiency "thermal conduction bridge" in the cooling system, thereby constructing a high-efficiency thermal conduction network. According to the theory of nanofluid thermal conduction, this reasonable structural design can significantly improve the thermal conductivity of the composite coolant compared to pure pentaerythritol ester. The improvement of thermal conductivity is directly related to the performance of the lithium battery thermal management system, which can make the system more quickly and efficiently dissipate the heat generated during battery operation, ensuring that the battery operates in a suitable temperature environment.

[0015] Secondly, the modified nanoparticles can achieve uniform dispersion in the pentaerythritol ester matrix without agglomeration. This excellent dispersion avoids the formation of conductive pathways, fundamentally reducing safety hazards caused by conductivity issues. The addition of Al2O3 nanoparticles can improve the dielectric strength of the synthesized ester coolant. This property effectively prevents breakdown under high-voltage electric fields, significantly enhancing the electrochemical stability of the battery system and providing a solid guarantee for the safe operation of lithium batteries. In short, this results in a green coolant that balances high thermal conductivity, excellent chemical stability, and environmental compatibility, meeting the stringent requirements of electric vehicles and energy storage systems for battery thermal management. Attached Figure Description

[0016] Figure 1 This is a flowchart of the preparation method of the lithium battery immersion coolant containing surface-modified alumina nanoparticles in Embodiment 1 of the present invention. Detailed Implementation

[0017] The following detailed description illustrates the specific implementation method: Example 1 A lithium-ion battery immersion coolant containing surface-modified alumina nanoparticles, the coolant comprising the following components by mass percentage: 60%-90% pentaerythritol ester matrix, 0.5%-5% surface-modified Al2O3 nanoparticles, 0.1%-1% silane coupling agent modifier, 0.1%-0.5% auxiliary stabilizer, and 3.5%-39.3% anhydrous ethanol. The surface-modified Al2O3 nanoparticles have a particle size of 20-100 nm. In this embodiment, the particle size of the surface-modified Al2O3 nanoparticles is 50 nm.

[0018] The silane coupling agent modifier is γ-methacryloxypropyltrimethoxysilane or γ-aminopropyltriethoxysilane. In this embodiment, γ-methacryloxypropyltrimethoxysilane (KH-570) is used.

[0019] The auxiliary stabilizer is vitamin E acetate or lecithin. In this embodiment, vitamin E acetate is used.

[0020] like Figure 1 As shown, the method for preparing the coolant includes the following steps: Step 1: Add Al2O3 nanoparticles to anhydrous ethanol (solid-liquid ratio 1:10-1:20) and ultrasonically disperse for 30 min; add silane coupling agent (pH adjusted to 4-6, acetic acid adjusted), and magnetically stir at 60-80℃ for 2 h to form an lipophilic surface (contact angle ≥90°); centrifuge and wash (8000 rpm, 3 times), and vacuum dry (60℃, 12 h) to obtain modified particles. Step two, the modified particles and auxiliary stabilizer are added into pentaerythritol ester in proportion, pre-dispersed (high speed stirring 2000 rpm, 1 h), and then ultrasonic treated (power ≥ 400 W, frequency 20-40 kHz, time 60-90 min) to form a homogeneous stable system (zeta potential absolute value ≥ 30 mV).

[0021] For example, the components and mass fractions of the coolant in this embodiment are as follows: pentaerythritol ester: 80.0%, Al2O3nanoparticles: 2.0%, KH-57 silane coupling agent: 0.2%, vitamin E acetate: 0.3%, and anhydrous ethanol: the balance; In the specific preparation, 20 g of Al2O3nanoparticles are added into 200 mL of anhydrous ethanol, poured into a three-necked flask, and connected to a condensation reflux device. The nanoparticles are dispersed in an ultrasonic cleaner (power 500 W, frequency 40 kHz) for 2 h to avoid agglomeration. 2 g of KH-570 is added, and glacial acetic acid is added dropwise to adjust the pH of the system to 4.5 (monitored by precision pH paper) to enhance the hydrolysis efficiency of the silane. The temperature is raised to 70°C, and magnetic stirring (speed 300 rpm) is started. The reflux reaction is carried out for 2 h to make the silane coupling agent hydrolyze to form active groups and undergo condensation reaction with the surface hydroxyl groups of Al2O3to form a -SiO-Al bonding layer. After the reaction is completed, the suspension is transferred to a centrifuge (speed 8000 rpm) and centrifuged for 15 min. The supernatant is discarded, and the precipitate is washed with anhydrous ethanol for 3 times to remove unreacted silane. Then, the precipitate is placed in a vacuum drying oven (temperature 60°C, pressure less than 16 kPa) for 24 h to eliminate moisture and internal micro-bubbles. Active groups, and undergo condensation reaction with the surface hydroxyl groups of Al2O3to form a -SiO-Al bonding layer. After the reaction is completed, the suspension is transferred to a centrifuge (speed 8000 rpm) and centrifuged for 15 min. The supernatant is discarded, and the precipitate is washed with anhydrous ethanol for 3 times to remove unreacted silane. Then, the precipitate is placed in a vacuum drying oven (temperature 60°C, pressure less than 16 kPa) for 24 h to eliminate moisture and internal micro-bubbles.

[0022] 80 g of pentaerythritol ester is poured into a beaker, 2 g of modified Al2O3particles and 0.3 g of vitamin E acetate are added, and an electric stirrer (speed 2000 rpm) is used to stir for 1 h to preliminarily disperse the particles in the matrix. The mixture is transferred to an ultrasonic processor (power 600 W, probe diameter 6 mm, pulse mode: work for 3 s, pause for 1 s), and ultrasonic treated at 25°C for 90 min. After the dispersion is completed, a small amount of sample is taken to test the particle size distribution uniformity by a particle size analyzer. No obvious precipitation or stratification is observed, and a uniform and stable coolant sample is obtained.

[0023] The above-mentioned are only embodiments of the present application, and the common knowledge of the specific structure and characteristics in the scheme is described too much, the ordinary skilled in the art knows all the ordinary technical knowledge in the field of the present application before the application date or the priority date, can know all the prior art in the field, and has the ability to apply the conventional experimental means before the date, the ordinary skilled in the art can perfect and implement the scheme under the enlightenment given by the present application combined with their own ability, some typical known structure or known method should not become the obstacle for the ordinary skilled in the art to implement the present application. It should be pointed out that for those skilled in the art, without departing from the structure of the present application, a number of modifications and improvements can also be made, which should also be considered as the protection scope of the present application, which will not affect the effect and practicality of the patent. The protection scope of the present application should be subject to the content of its claims, and the specific implementation mode and the like in the specification can be used to explain the content of the claims.

Claims

1. A lithium battery immersion coolant comprising surface-modified alumina nanoparticles, characterized by: The coolant comprises the following mass percentages of components: 60%-90% of pentaerythritol ester base, 0.5%-5% of surface modified Al2O3 nanoparticles, 0.1%-1% of silane coupling agent modifier, 0.1%-0.5% of auxiliary stabilizer and 3.5%-39.3% of anhydrous ethanol.

2. The lithium battery immersion coolant containing surface-modified alumina nanoparticles according to claim 1, characterized by: The particle size of the surface modified Al2O3 nanoparticles is 20-100 nm.

3. The lithium battery immersion coolant containing surface-modified alumina nanoparticles according to claim 2, characterized by: The particle size of the surface modified Al2O3 nanoparticles is 50 nm.

4. The lithium battery immersion coolant containing surface-modified alumina nanoparticles according to claim 3, characterized by: The silane coupling agent modifier is γ-methacryloxypropyl trimethoxysilane or γ-aminopropyl triethoxysilane.

5. The lithium battery immersion coolant containing surface-modified alumina nanoparticles according to claim 4, characterized by: The auxiliary stabilizer is vitamin E acetate or lecithin.

6. The lithium battery immersion coolant containing surface-modified alumina nanoparticles according to claim 5, characterized by: The preparation method of the coolant comprises the following steps: Step one, Al2O3 nanoparticles are added into anhydrous ethanol and ultrasonically dispersed for 30 min; a silane coupling agent modifier is added, and magnetic stirring is carried out at 60-80 ℃ for 2 h to form a lipophilic surface; the modified particles are centrifuged, washed and vacuum dried to obtain the modified particles; Step two, the modified particles and the auxiliary stabilizer are added into pentaerythritol ester in proportion, pre-dispersed and ultrasonically treated to form a homogeneous stable system, and the preparation of the coolant sample is completed.

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