A lithium battery immersion cooling medium composition, and a preparation method and application thereof

Abstract

This invention relates to a lithium battery immersion cooling medium composition, its preparation method, and its application. The lithium battery immersion cooling medium composition comprises a base oil, a flame retardant, an antioxidant, and pentaerythritol ester; the base oil is a polyalphaolefin, and the flame retardant comprises 3.1-4.2 parts by weight of triisopropylphenyl phosphate, 1.7-3.9 parts by weight of trixylenol phosphate, 2.5-7.8 parts by weight of tert-butylphenyltriphenyl phosphate, 1.6-5.5 parts by weight of isodecyl diphenyl phosphate, and 3.2-6.7 parts by weight of triphenyl phosphate. This lithium battery immersion cooling medium composition maintains good flame retardant performance under low viscosity conditions, better meeting the requirements for lithium battery immersion cooling.

Description

Technical Field

[0001] This invention relates to the field of lithium battery cooling, and more particularly to a lithium battery immersion cooling medium composition, its preparation method, and its application. Background Technology

[0002] Currently, the batteries used in pure electric vehicles and energy storage are mainly ternary lithium and lithium iron phosphate batteries. However, the performance, lifespan, and safety of lithium batteries are highly sensitive to temperature. Studies have shown that the optimal operating temperature for lithium batteries is 20-40℃. Excessively high or low temperatures can affect the battery's charging and discharging efficiency and lifespan, and even cause safety accidents. Lithium batteries release a large amount of heat during charging and discharging, especially at high charge / discharge rates, where a large amount of heat can be generated instantaneously, with the internal temperature of the battery exceeding 100℃. This heat accumulates in the relatively confined space of the battery pack over time, and the dense packing of cells further complicates heat dissipation in the central areas, exacerbating temperature inconsistencies between cells. This results in reduced charging and discharging efficiency and decreased battery power; in severe cases, it can lead to thermal runaway, affecting system safety and lifespan. To ensure optimal performance, safety, and lifespan of power batteries, thermal management is necessary to control the battery operating temperature within the optimal range. This is of great significance for the development and safe use of electric vehicles.

[0003] Currently, the main cooling methods for lithium batteries are air cooling and liquid cooling with cold plates. However, with the increasing demand for energy storage and the increase in charge and discharge power rates, the heat generated by lithium batteries also increases. Traditional air cooling and liquid cooling with cold plates are difficult to meet the requirements due to their low cooling efficiency and uneven temperature. Immersion cooling technology, on the other hand, greatly improves the safety performance of lithium batteries due to its high cooling efficiency. The immersion cooling medium needs to have the characteristics of good fluidity (low kinematic viscosity), non-flammability, non-explosiveness, and low conductivity. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention provides a lithium battery immersion cooling medium composition. This engine oil composition can maintain good flame retardant properties under low viscosity conditions, better meeting the requirements for lithium battery immersion cooling.

[0005] In a first aspect, the present invention provides a lithium battery immersion cooling medium composition, comprising a base oil, a flame retardant, an antioxidant, and a pentaerythritol ester; wherein the base oil is a polyalphaolefin, and the flame retardant comprises 3.1 to 4.2 parts by weight of triisopropylphenyl phosphate, 1.7 to 3.9 parts by weight of trixylenol phosphate, 2.5 to 7.8 parts by weight of tert-butylphenyltriphenyl phosphate, 1.6 to 5.5 parts by weight of isodecyl diphenyl phosphate, and 3.2 to 6.7 parts by weight of triphenyl phosphate.

[0006] This invention selects specific base oils and additives, and optimizes the composition of flame retardants to obtain an immersion cooling medium with flame-retardant effects. This medium maintains better flame-retardant performance under low viscosity conditions, thus better meeting the requirements for immersion cooling of lithium batteries. The immersion cooling medium provided by this invention possesses excellent properties such as good fluidity, non-flammability, non-explosiveness, and low electrical conductivity.

[0007] Preferably, based on the total weight of the lithium battery immersion cooling medium composition, the lithium battery immersion cooling medium composition comprises: 10-20% by weight of pentaerythritol ester, 13-18% by weight of flame retardant, 1.5-2.8% by weight of antioxidant, and the balance being polyalphaolefin.

[0008] Preferably, the viscosity index of the polyalphaolefin is greater than 140; and / or, the kinematic viscosity of the polyalphaolefin at 100°C is ≤3 mm. 2 •s -1 ; and / or, the polyalphaolefin is a Group IV base oil.

[0009] Preferably, the weight ratio of triisopropylphenyl phosphate, tris(2-xylene) phosphate, tert-butylphenyl triphenyl phosphate, isodecyl diphenyl phosphate, and triphenyl phosphate is (3.2~4.0):(1.8~3.5):(3.0~6.5):(1.8~5.0):(3.8~6.0). In this invention, optimizing the ratio of triisopropylphenyl phosphate, tris(2-xylene) phosphate, tert-butylphenyl triphenyl phosphate, isodecyl diphenyl phosphate, and triphenyl phosphate can improve the cooling and flame-retardant effects of the immersion cooling medium.

[0010] Further preferably, the weight ratio of triisopropylphenyl phosphate, tris(2-xyl)-xylphenol phosphate, tert-butylphenyltriphenyl phosphate, isodecyl diphenyl phosphate and triphenyl phosphate is (3.5~4.0):(2.0~3.0):(3.5~5.0):(3.0~3.5):(4.0~4.5).

[0011] In this invention, by optimizing the base oil, flame retardant and other additives, especially the immersion cooling medium with the preferred proportion of flame retardant, it has a better flame retardant effect, is not easily flammable or explosive, and has excellent fluidity, electrical conductivity and other properties, resulting in better overall performance.

[0012] Preferably, the pentaerythritol ester has the structure of formula (1):

[0013] Where R1~R 10 The number of carbon atoms in each is 4 to 10.

[0014] Preferably, the antioxidant is selected from one or more of phenolic ester antioxidants, phenolic antioxidants, and amine antioxidants; the phenolic ester antioxidant is octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate or β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate; the amine antioxidant is alkylated diphenylamine or octylbutyldiphenylamine antioxidant; and the phenolic antioxidant is 2,6-di-tert-butyl-p-methylphenol or 4,4'-methylenebis(2,6-di-tert-butylphenol).

[0015] More preferably, the antioxidant is a composition of phenolic antioxidant and amine antioxidant; the weight ratio of the phenolic antioxidant to the amine antioxidant is 1:(0.5~2).

[0016] Secondly, the present invention provides a method for preparing the lithium battery immersion cooling medium composition, comprising mixing polyalphaolefin, pentaerythritol ester, flame retardant and antioxidant.

[0017] Preferably, the process involves mixing and stirring the polyalphaolefin and pentaerythritol ester at 50-60°C until homogeneous, then adding the flame retardant and antioxidant to the polyalphaolefin and pentaerythritol ester mixture and continuing to mix at 50-60°C for 2-3 hours.

[0018] Thirdly, the present invention provides the application of the lithium battery immersion cooling medium composition or the lithium battery immersion cooling medium composition obtained by the preparation method of the lithium battery immersion cooling medium composition in lithium battery immersion cooling.

[0019] The beneficial effects of the present invention are at least as follows: the lithium battery immersion cooling medium composition provided by the present invention can meet the requirements of lithium battery immersion cooling, has good fluidity (low kinematic viscosity), is non-flammable, non-explosive, and has low electrical conductivity, and is particularly effective in maintaining a certain heat dissipation efficiency and flame retardant performance. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0021] Figure 1 This is a schematic diagram of the cooling efficiency testing method provided by the present invention. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0023] Unless otherwise specified, the raw materials, reagents, instruments, and equipment involved in the embodiments of this invention can all be obtained by purchase. The raw materials used in this invention are shown in Table 1.

[0024] In this embodiment of the invention, the pentaerythritol ester in the raw materials is a tetraester, specifically as shown in formula (1), wherein R7, R8, R9, and R 10 =4, 4, 4, 4; PAO2 data in raw materials are shown in Table 2.

[0025] Table 1

[0026] Table 2

[0027] Example 1

[0028] The composition consists of the following components in weight percentages.

[0029] Table 3

[0030] The preparation method is as follows: PAO 2 and pentaerythritol ester are mixed and stirred evenly at 60°C. Then, flame retardant and antioxidant are added to the mixture of PAO 2 and pentaerythritol ester and mixed at 60°C. After stirring evenly, the mixture is stirred for 2.5 hours to obtain an immersion cooling medium.

[0031] Example 2

[0032] The difference between this embodiment and Embodiment 1 lies in the change of the flame retardant ratio, as shown in Table 4.

[0033] Table 4

[0034] Comparative Example 1

[0035] Compared with Example 1, the difference in this embodiment is that the total weight of the flame retardant is adjusted to 12%, and the specific changes of the flame retardant are shown in Table 5. In addition, the proportion of PAO 2 is increased by 5.7% by weight.

[0036] Table 5

[0037] Comparative Example 2

[0038] The only difference between this comparative example and Example 1 is that no flame retardant is added.

[0039] Comparative Example 3

[0040] The only difference between this comparative example and Example 1 is that the weight ratio of the flame retardant is 4.3:10.2:6:8.8:7.2 for triisopropylphenyl phosphate:trixylenol phosphate:tert-butylphenyltriphenyl phosphate:isodecyldiphenyl phosphate:triphenyl phosphate.

[0041] Test Example 1

[0042] The flame retardancy test method adopted is NB / SH / T 0567-2016 Determination of flammability of liquids in contact with hot surfaces: manifold ignition method.

[0043] Cooling efficiency test method: Specific test equipment as follows Figure 1 The fluid domain shown has an initial cooling medium temperature of 40℃, an inlet temperature of 15℃, an inlet flow rate of 2.67 L / min, a discharge rate of 3C, and uses ternary 523 lithium batteries with a rated voltage of 3.65V, a rated capacity of 40Ah, and a single cell heating power of 29W. The calculation time is 1200s. The outlet temperature of the cooling medium is tested.

[0044] Table 6 Test Comparison Results

[0045] As shown in Table 6, when the kinematic viscosity of Examples 1, 2, 1, 2, and 3 is basically the same, the cooling effect of Examples 1, 2, and 1 is better, according to the cooling outlet temperature test, followed by Comparative Examples 2 and 3. According to the manifold ignition test, the flame retardant effect of Examples 1 and 2 is better than that of Comparative Example 1, followed by Comparative Example 2, and Comparative Example 3 has the worst flame retardant performance.

[0046] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A lithium battery immersion cooling medium composition, characterized in that, It includes base oil, flame retardant, antioxidant and pentaerythritol ester; the base oil is polyalphaolefin, and the flame retardant includes 3.1 to 4.2 parts by weight of triisopropylphenyl phosphate, 1.7 to 3.9 parts by weight of trixylenol phosphate, 2.5 to 7.8 parts by weight of tert-butylphenyltriphenyl phosphate, 1.6 to 5.5 parts by weight of isodecyl diphenyl phosphate and 3.2 to 6.7 parts by weight of triphenyl phosphate.

2. The lithium battery immersion cooling medium composition according to claim 1, characterized in that, Based on the total weight of the lithium battery immersion cooling medium composition, the lithium battery immersion cooling medium composition comprises: 10-20% by weight of pentaerythritol ester, 13-18% by weight of flame retardant, 1.5-2.8% by weight of antioxidant, and the balance being polyalphaolefin.

3. The lithium battery immersion cooling medium composition according to claim 1 or 2, characterized in that, The viscosity index of the polyalphaolefin is greater than 140; and / or, the kinematic viscosity of the polyalphaolefin at 100°C is ≤3 mm. 2 •s -1 ; and / or, the polyalphaolefin is a Group IV base oil.

4. The lithium battery immersion cooling medium composition according to any one of claims 1-3, characterized in that, The weight ratio of triisopropylphenyl phosphate, tris(2-xylenol) phosphate, tert-butylphenyltriphenyl phosphate, isodecyl diphenyl phosphate and triphenyl phosphate is (3.2~4.0):(1.8~3.5):(3.0~6.5):(1.8~5.0):(3.8~6.0).

5. The lithium battery immersion cooling medium composition according to claim 4, characterized in that, The weight ratio of triisopropylphenyl phosphate, tris(2-xyl)-xylphenol phosphate, tert-butylphenyltriphenyl phosphate, isodecyl diphenyl phosphate and triphenyl phosphate is (3.5~4.0):(2.0~3.0):(3.5~5.0):(3.0~3.5):(4.0~4.5).

6. The lithium battery immersion cooling medium composition according to any one of claims 1-5, characterized in that, The pentaerythritol ester has the structure of formula (1): Where R1~R 10 The number of carbon atoms in each is 4 to 10.

7. The lithium battery immersion cooling medium composition according to any one of claims 1-6, characterized in that, The antioxidant is selected from one or more of phenolic ester antioxidants, phenolic antioxidants, and amine antioxidants; preferably, the phenolic ester antioxidant is octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate or β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, the amine antioxidant is alkylated diphenylamine or octylbutyldiphenylamine antioxidant, and the phenolic antioxidant is 2,6-di-tert-butyl-p-methylphenol or 4,4'-methylenebis(2,6-di-tert-butylphenol).

8. The lithium battery immersion cooling medium composition according to claim 7, characterized in that, The antioxidant is a composition of phenolic antioxidant and amine antioxidant; the weight ratio of the phenolic antioxidant to the amine antioxidant is 1:(0.5~2).

9. A method for preparing the lithium battery immersion cooling medium composition according to any one of claims 1-8, characterized in that, This includes mixing polyalphaolefins, pentaerythritol esters, flame retardants, and antioxidants; Preferably, the process involves mixing and stirring the polyalphaolefin and pentaerythritol ester at 50-60°C until homogeneous, then adding the flame retardant and antioxidant to the polyalphaolefin and pentaerythritol ester mixture and continuing to mix at 50-60°C for 2-3 hours.

10. The application of the lithium battery immersion cooling medium composition according to any one of claims 1-8 or the lithium battery immersion cooling medium composition according to claim 9 in the immersion cooling of lithium batteries.

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