Immersion cooling liquid for battery, and preparation method therefor and use thereof

Abstract

The present invention provides an immersion cooling liquid for a battery, and a preparation method therefor and a use thereof. The immersion cooling liquid for a battery comprises the following components in parts by weight: 40-70 parts of insulating cooling oil, 30-60 parts of a flame retardant, and 0.2-2 parts of a stabilizer, wherein the insulating cooling oil is selected from one or more of mineral oil, macromolecular hydrocarbon oil, silicone oil, a synthetic ester, and vegetable oil, and the flame retardant is a halogenated hydrocarbon having 2 to 4 carbon atoms. In the present invention, by combining the halogenated hydrocarbon having 2 to 4 carbon atoms with the insulating cooling oil, the obtained immersion cooling liquid for a battery has the advantages of good flame retardancy, high insulating properties, good low-temperature fluidity, excellent heat transfer performance, etc., and can effectively inhibit the occurrence of battery thermal runaway and reduce the harm caused by battery thermal runaway. In addition, the present invention involves a simple preparation process and low costs, is convenient for large-scale production, and has good application prospects.

Description

A battery immersion coolant and its preparation method and application

[0001] Cross-references

[0002] This application claims priority to Chinese Patent Application No. 2024100840332, filed on January 19, 2024, entitled “A Battery Immersion Coolant, Preparation Method and Application Thereof,” the disclosure of which is incorporated herein by reference in its entirety. Technical Field

[0003] The present invention relates to the field of battery safety technology, and in particular to a battery immersion coolant, a preparation method thereof, and applications thereof. Background Art

[0004] Coolant is the core of an immersion battery thermal management system. Its thermophysical properties largely determine the operating performance of the battery system. Currently, the coolants used in immersion thermal management systems both domestically and internationally fall into five main categories: electronic fluoride fluids, hydrocarbons, esters, silicone oils, and water-based coolants.

[0005] The principles for selecting coolant are as follows: ① The coolant should be non-conductive, that is, have a low dielectric constant; ② The coolant should have excellent thermal conductivity, that is, high specific heat capacity and high thermal conductivity; ③ The coolant should not solidify or burn within the operating temperature range, that is, have a low freezing point, be non-flammable or have a high flash point; ④ The coolant should be compatible with the materials of the lithium battery system, that is, have no corrosive effect on the materials in direct contact; ⑤ The premise for large-scale use of the coolant is that it should be environmentally friendly, including zero ozone depletion potential (ODP) and low global warming potential (GWP).

[0006] Electronic fluorinated fluids include hydrofluoroethers (HFE) and hydrofluoroolefins (HFO), which have low dielectric constants, material compatibility, and non-flammability safety, and have attracted much attention in the field of battery thermal management. However, electronic fluorinated fluids are expensive and have a high density, which greatly increases the cost of immersed energy storage batteries and makes them difficult to promote and apply on a large scale. Although hydrocarbons, esters, and silicone oils have good insulation properties, their heat dissipation and safety performance are poor, making it difficult to effectively control and reduce the thermal runaway hazards of batteries. Water-based coolants are water-based fluids such as deionized water and water-ethylene glycol solutions and nanofluids. They have high cooling capacity and low cost, but their insulation properties are poor, making them difficult to apply in the field of battery immersion coolants.

[0007] Summary of the Invention

[0008] In view of the deficiencies in the prior art, the present invention provides a battery immersion coolant and a preparation method and application thereof.

[0009] In a first aspect, the present invention provides a battery immersion coolant comprising the following components in parts by weight: 40 to 70 parts of insulating cooling oil, 30 to 60 parts of a flame retardant, and 0.2 to 2 parts of a stabilizer;

[0010] The insulating cooling oil is selected from one or more of mineral oil, macromolecular hydrocarbon oil, silicone oil, synthetic ester, and vegetable oil;

[0011] The flame retardant is a halogenated hydrocarbon with 2 to 4 carbon atoms.

[0012] As mentioned above, insulating cooling oil has good insulation properties, but poor heat dissipation and safety. The conventional idea in this field is to add flame retardants thereto, but traditional flame retardants are almost insoluble in the above-mentioned insulating cooling oil. Even if they are soluble in the above-mentioned insulating cooling oil, the performance of the oil is greatly damaged. In response to this problem, the improvement route attempted by those skilled in the art is to add additional solubilizers to make the insulating cooling oil compatible with the flame retardant. In the present invention, the inventor unexpectedly discovered that the use of halogenated hydrocarbons with a carbon number of 2-4, that is, low-molecular-weight halogenated hydrocarbons, can give the insulating cooling oil good flame retardancy, and has almost no effect on the performance of the insulating cooling oil itself, and can even improve it. The low-molecular-weight halogenated hydrocarbons used in the present invention are not a conventional flame retardant, so the solution of the present invention is not easy to think of. In the present invention, the reason why low-molecular-weight halogenated hydrocarbons can play a role may be because small molecular substances have a relatively low boiling point and small intermolecular forces, are easily volatilized or decomposed at high temperatures, and release a large amount of halogen flame retardant elements, quenching the combustion factor, and achieving a highly efficient flame retardant effect.

[0013] The battery immersion coolant of the present invention has high flame retardancy, high insulation, good low-temperature fluidity, and good heat transfer performance. It can effectively inhibit the occurrence of battery thermal runaway, reduce the hazards caused by battery thermal runaway, and improve safety.

[0014] Among them, mineral oil includes No. 10 transformer insulating cooling oil, No. 25 transformer insulating cooling oil, No. 45 transformer insulating cooling oil, etc.

[0015] Macromolecular hydrocarbon oils include α oil, β oil, α polyolefins, etc.

[0016] Vegetable oils include common vegetable oils such as soybean oil, corn oil, peanut oil, etc.

[0017] Silicone oil includes methyl silicone oil, ethyl silicone oil and functionalized silicone oil, such as dimethyl silicone oil, diethyl silicone oil, benzyl silicone oil, amino methyl silicone oil, etc.

[0018] Synthetic esters include monoesters, diesters, polyol esters, phosphate esters, etc., such as methyl oleate, diethylhexyl carbonate, triethylhexanoin, trioctyl phosphate, etc.

[0019] The halogen in the halogenated hydrocarbon of the present invention may be one or more of fluorine, chlorine, bromine and iodine.

[0020] In some embodiments of the present invention, the flame retardant is selected from one or more of tetrachloroethylene, tetrachloroethane, tetrabromoethane, tetrabromoethylene, hexachloroethane, dibromotetrafluoroethane, dibromotetrachloroethane, tribromotrifluoroethane, 1,2-dibromo-1-chloro-1,2,2-trifluoroethane, dibromohexafluoropropane, trichloropentafluoropropane, hexachloropropylene, hexachlorobutadiene, dibromooctafluorobutane, dibromohexafluorocyclobutane, dichlorooctafluorobutane, dichlorohexafluorocyclobutane, and diiodoperfluorobutane.

[0021] Preferably, the flame retardant is selected from one or more of tetrachloroethylene, tetrachloroethane, hexachloropropylene, and hexachlorobutadiene.

[0022] In some embodiments of the present invention, the insulating cooling oil is selected from one or more of No. 10 transformer insulating cooling oil, No. 25 transformer insulating cooling oil, and No. 45 transformer insulating cooling oil.

[0023] In some embodiments of the present invention, the stabilizer is a phenolic stabilizer.

[0024] More preferably, the stabilizer is selected from one or more of o-cresol, hydroquinone, thymol, and 2,6-di-tert-butyl-p-cresol.

[0025] In a preferred embodiment of the present invention, the battery immersion coolant comprises the following components in parts by weight: 40 to 65 parts of insulating cooling oil, 35 to 60 parts of flame retardant, and 0.5 to 2 parts of stabilizer; more preferably, 40 to 60 parts of insulating cooling oil, 40 to 60 parts of flame retardant, and 0.5 to 2 parts of stabilizer.

[0026] Among them, the insulating cooling oil is selected from one or more of No. 10 transformer insulating cooling oil, No. 25 transformer insulating cooling oil, and No. 45 transformer insulating cooling oil; the flame retardant is selected from one or more of tetrachloroethylene, tetrachloroethane, hexachloropropylene, and hexachlorobutadiene; the stabilizer is selected from one or more of o-cresol, hydroquinone, thymol, and 2,6-di-tert-butyl-p-cresol.

[0027] In some embodiments of the present invention, the battery immersion coolant is used as an immersion coolant for lithium batteries.

[0028] In a second aspect, the present invention provides a method for preparing the above-mentioned battery immersion coolant.

[0029] The preparation method provided by the invention comprises the steps of blending the components under heating and stirring conditions to obtain a uniform liquid.

[0030] Preferably, the heating temperature is 50-80° C., the stirring speed is 600-1200 r / min, and the stirring time is 2-6 h.

[0031] In a third aspect, the present invention provides a battery thermal management system comprising the aforementioned battery immersion coolant. The battery immersion coolant of the present invention can ensure stable operation of the battery thermal management system.

[0032] The present invention provides a battery immersion coolant, its preparation method, and application. By selecting a halogenated hydrocarbon with 2-4 carbon atoms, the insulating cooling oil is not only given good flame retardancy, but also has good compatibility with the insulating cooling oil. While improving the flame retardancy of the insulating cooling oil, the physical and chemical properties of the insulating cooling oil are further optimized and improved. The battery immersion coolant of the present invention has the advantages of good flame retardancy, high insulation, low-temperature fluidity, and heat transfer performance. It can effectively inhibit the occurrence of battery thermal runaway and reduce the harm caused by battery thermal runaway. In addition, the preparation process of the present invention is simple, low-cost, and easy to large-scale production, and has good application prospects. DETAILED DESCRIPTION

[0033] To make the objectives, technical solutions, and advantages of the present invention more clear, the technical solutions of the present invention are described clearly and completely below. Obviously, the embodiments described are only some of the embodiments of the present invention, not all of them. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0034] If no specific techniques or conditions are specified in the examples, the experiments were carried out according to the techniques or conditions described in the literature in the field or according to the product instructions. If no manufacturer is specified for the reagents or instruments used, they are all conventional products that can be purchased through regular channels.

[0035] In the following examples, unless otherwise specified, the numbers of parts are by mass.

[0036] Example 1

[0037] This embodiment provides a lithium battery immersion coolant, which is prepared by the following method: 70 parts of No. 25 transformer insulating cooling oil, 30 parts of tetrachloroethylene, and 0.5 parts of hydroquinone are weighed and blended, and the mixture is stirred at 60°C and 800 r / min for 2 hours to obtain the lithium battery immersion coolant.

[0038] Example 2

[0039] This embodiment provides a lithium battery immersion coolant, which is prepared by the following method: 40 parts of No. 25 transformer insulating cooling oil, 60 parts of tetrachloroethylene, and 2 parts of hydroquinone are weighed and blended, and the mixture is stirred at 60°C and 800 r / min for 6 hours to obtain the lithium battery immersion coolant.

[0040] Example 3

[0041] This embodiment provides a lithium battery immersion coolant, which is prepared by the following method: 60 parts of No. 25 transformer insulating cooling oil, 40 parts of tetrachloroethylene, and 1 part of hydroquinone are weighed and blended, and the mixture is stirred at 60°C and 800 r / min for 3 hours to obtain the lithium battery immersion coolant.

[0042] Example 4

[0043] This embodiment provides a lithium battery immersion coolant, which is prepared by the following method: 50 parts of No. 25 transformer insulating cooling oil, 50 parts of tetrachloroethylene, and 1.5 parts of hydroquinone are weighed and blended, and the mixture is stirred at 60°C and 800 r / min for 4 hours to obtain the lithium battery immersion coolant.

[0044] Example 5

[0045] This embodiment provides a lithium battery immersion coolant, which is prepared by the following method: 60 parts of No. 25 transformer insulating cooling oil, 40 parts of tetrachloroethane, and 1 part of thymol are weighed and blended, and the mixture is stirred at 70°C and a stirring speed of 1000 r / min for 3 hours to obtain a lithium battery immersion coolant.

[0046] Example 6

[0047] This embodiment provides a lithium battery immersion coolant, which is prepared by the following method: 60 parts of No. 10 transformer insulating cooling oil, 20 parts of tetrachloroethylene, 20 parts of hexachloropropylene, and 1 part of thymol are weighed and blended, and the mixture is stirred at 80° C. and a stirring speed of 1000 r / min for 4 hours to obtain a lithium battery immersion coolant.

[0048] Example 7

[0049] This embodiment provides a lithium battery immersion coolant, which is prepared by the following method: 60 parts of No. 25 transformer insulating cooling oil, 40 parts of hexachlorobutadiene, and 1 part of thymol are weighed and blended, and the mixture is stirred at 70° C. and a stirring speed of 1000 r / min for 3 hours to obtain a lithium battery immersion coolant.

[0050] Comparative Example 1

[0051] This comparative example provides a lithium battery immersion coolant, which is prepared by the following method: 80 parts of No. 25 transformer insulating cooling oil, 20 parts of tetrachloroethylene, and 0.5 parts of hydroquinone are weighed and blended, and stirred at 60°C and 800 r / min for 2 hours to obtain a lithium battery immersion coolant.

[0052] Comparative Example 2

[0053] The commercially available 3M Novec 7200 fluorinated liquid was used as the coolant for the comparative experiment.

[0054] Comparative Example 3

[0055] This comparative example provides a lithium battery immersion coolant, which is prepared by the following method: 70 parts of No. 25 transformer insulating cooling oil, 30 parts of perfluorooctyl bromide, and 0.5 parts of hydroquinone are weighed and blended, and stirred and mixed at a temperature of 60°C and a stirring speed of 800 r / min for 2 hours to obtain a lithium battery immersion coolant.

[0056] Comparative Example 4

[0057] This comparative example provides a lithium battery immersion coolant, which is prepared by the following method: 70 parts of No. 25 transformer insulating cooling oil, 30 parts of ammonium polyphosphate, and 0.5 parts of hydroquinone are weighed and blended, and stirred and mixed at a temperature of 60°C and a stirring speed of 800 r / min for 2 hours to obtain a lithium battery immersion coolant.

[0058] Performance Testing

[0059] The coolants of various embodiments and comparative examples were tested for their physical and chemical properties and safety performance.

[0060] The test method is as follows:

[0061] Physical and chemical performance test: referring to GB2536 and GB / T507 test methods, the physical and chemical performance test of the coolant involved in the present invention was carried out.

[0062] Safety Performance Test: Five 100% SOC battery cells (rated capacity 45Ah, rated voltage 3.5V) were placed in a battery holder in a series arrangement, simulating a five-cell series module. The center cell was overcharged and secured with a clamp. Thermocouples were placed in the center of the top and bottom surfaces of the overcharged cells for temperature measurement. After this setup, 1C charging was continued until overcharge became uncontrolled, and the battery module's behavior was observed in different media.

[0063] The results are shown in Tables 1 and 2.

[0064] Table 1 Main parameters of physical and chemical properties

[0065] Physical and chemical performance tests revealed that the coolant provided by the present invention exhibits excellent flame retardancy, achieving flame retardancy or non-flammability, and possesses excellent insulation properties. Its breakdown voltage and insulation resistance are significantly higher than those of 3M 7200 fluorinated liquid, while its leakage current is significantly lower than that of fluorinated liquid, further demonstrating the coolant's excellent insulation properties. Compared to unmodified No. 25 insulating cooling oil, the present invention further improves the physical and chemical properties of the insulating cooling oil. Compared to Comparative Example 1, increasing the amount of flame retardant added initially increases and then decreases the breakdown voltage, while flame retardancy decreases with a lower addition amount.

[0066] Table 2 Safety test of battery modules in different media

[0067] Safety experiments have shown that the overcharge runaway temperature of lithium batteries in the air is high, and all five battery cells experience thermal runaway, which is very dangerous. The coolant provided by the present invention has the same safety as 3M fluorinated liquid, effectively inhibits the spread of thermal runaway, reduces the hazards caused by thermal runaway, and has good application prospects.

[0068] It should be noted that the endpoints of the ranges and any values ​​disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoints of each range, the endpoints of each range and individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be considered to be specifically disclosed herein.

[0069] In the description of this specification, the reference terms "one embodiment", "some embodiments", "specific implementation methods", or "some specific implementation methods" and the like mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the embodiments of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine different embodiments or examples described in this specification and features of different embodiments or examples without contradiction.

[0070] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention. Industrial Applicability

[0071] The present invention provides a battery immersion coolant, its preparation method, and application. The battery immersion coolant comprises the following components by weight: 40-70 parts of insulating cooling oil, 30-60 parts of flame retardant, and 0.2-2 parts of stabilizer; the insulating cooling oil is selected from one or more of mineral oil, macromolecular hydrocarbon oil, silicone oil, synthetic ester, and vegetable oil; and the flame retardant is a halogenated hydrocarbon with 2-4 carbon atoms. By combining the halogenated hydrocarbon with 2-4 carbon atoms with the insulating cooling oil, the battery immersion coolant obtained in the present invention exhibits excellent flame retardancy, high insulation, low-temperature fluidity, and heat transfer properties, effectively inhibiting the occurrence of battery thermal runaway and reducing the hazards caused by thermal runaway. Furthermore, the present invention has a simple preparation process, low cost, and is easy to scale up, thus possessing good economic value and application prospects.

Claims

1. A battery immersion coolant, characterized in that, It comprises the following components in parts by weight: 40 - 70 parts of insulating cooling oil, 30 - 60 parts of flame retardant, and 0.2 - 2 parts of stabilizer; The insulating cooling oil is selected from one or more of mineral oil, macromolecular hydrocarbon oil, silicone oil, synthetic ester, and vegetable oil; The flame retardant is a halogenated hydrocarbon with 2 - 4 carbon atoms.

2. The battery immersion coolant according to claim 1, wherein, The flame retardant is selected from one or more of tetrachloroethylene, tetrachloroethane, tetrabromoethane, tetrabromoethylene, hexachloroethane, dibromotetrafluoroethane, dibromotetrachloroethane, tribromotrifluoroethane, 1,2 - dibromo - 1 - chloro - 1,2,2 - trifluoroethane, dibromohexafluoropropane, trichloropentafluoropropane, hexachloropropene, hexachlorobutadiene, dibromooctafluorobutane, dibromohexafluorocyclobutane, dichlorooctafluorobutane, dichlorohexafluorocyclobutane, diiodoperfluorobutane; 3. The battery immersion coolant according to claim 2, wherein The flame retardant is selected from one or more of tetrachloroethylene, tetrachloroethane, hexachloropropene, hexachlorobutadiene; 4. The battery immersion coolant according to any one of claims 1 to 3, characterized in that, The insulating cooling oil is selected from one or more of No. 10 transformer insulating cooling oil, No. 25 transformer insulating cooling oil, No. 45 transformer insulating cooling oil; 5. The battery immersion coolant according to any one of claims 1-3, characterized in that, The stabilizer is a phenolic stabilizer.

6. The battery immersion coolant according to claim 5, wherein The stabilizer is selected from one or more of o - cresol, hydroquinone, thymol, 2,6 - di - tert - butyl - p - cresol; 7. The battery immersion coolant according to claim 6, characterized in that, The battery immersion coolant comprises the following components in parts by weight: 40 - 65 parts of insulating cooling oil, 35 - 60 parts of flame retardant, and 0.5 - 2 parts of stabilizer.

8. The preparation method of the battery immersion coolant according to any one of claims 1-7, characterized in that It includes the step of blending each component under heating and stirring conditions to obtain a homogeneous liquid.

9. The preparation method of the battery immersion coolant according to claim 8, wherein, The heating temperature is 50 - 80 °C, the stirring speed is 600 - 1200 r / min, and the stirring time is 2 - 6 h.

10. A battery thermal management system, characterized in that, It includes the battery immersion coolant according to any one of claims 1 - 7.

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