Lithium ion battery immersion coolant

Abstract

The application discloses a lithium ion battery immersion cooling liquid which is composed of propylene glycol, perfluorohexanone, dipropylene glycol methyl ether, an antifoaming agent, an inhibitor and 2,6-di-tert-butyl-p-cresol. The lithium ion battery immersion cooling liquid has excellent antifreezing, heat transfer, insulation, low-temperature fluidity and other performances, and is suitable for new energy vehicle and energy storage power station immersion liquid cooling systems.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of chemical technology, in particular to a kind of lithium ion battery immersion coolant, especially to high insulation, low viscosity, phase change immersion coolant, suitable for temperature control system of lithium ion battery for new energy vehicles or energy storage power station. BACKGROUND

[0002] Lithium ion battery is widely used in new energy vehicles and energy storage power station as energy storage device. Lithium ion battery has the best working temperature, and high temperature and low temperature will directly affect the service life, performance and safety of lithium ion battery. Therefore, the heat management with temperature control system is the key of lithium ion battery.

[0003] There are three ways of air cooling, liquid cooling and phase change for lithium ion battery heat management, and liquid cooling is an effective cooling method for lithium ion battery. Liquid cooling is generally divided into direct liquid cooling and indirect liquid cooling. In the aspect of indirect liquid cooling, water and water-glycol mixture are usually used as coolant due to cost-effective, but they need to use liquid cooling plate because of their conductivity. Compared with indirect liquid cooling, immersion liquid cooling can effectively reduce the heat of battery, and has the advantages of more uniform temperature and faster cooling speed. The 3M fluorinated liquid Novec 7100 has been used, which has many excellent properties such as insulation performance, non-combustion, phase change and fast heat conduction, and has been applied in data center and other fields. However, due to the high price, it is difficult to popularize and apply in new energy vehicles and energy storage power station.

[0004] Chinese patent CN112708398A discloses a cooling liquid for cooling integrated chip circuit board, which is composed of the following components: glycerol, triethanolamine 20-25 parts, perfluorohexanone, tetrafluoroethane, difluoro-chloromethane, trichloro-t-butyl alcohol, benzimidazole, paraffin, dimethyl silicone oil, silicon dioxide, hydroxyl silicone oil, tributyl phosphate. The immersion phase change cooling medium provided by the patent has high electrical insulation performance, low viscosity, low boiling point, high thermal conductivity, high latent heat of vaporization, good compatibility and stability, non-combustible and can inhibit combustion, etc., which can effectively protect the circuit in the computer mainboard, prevent the generation of dirt, and ensure the safe operation of the computer system. The patent only points out that it can be applied to integrated chip circuit board, and tetrafluoroethane is a gas at room temperature. In addition, the patent cannot provide low temperature fluidity below 0℃, so it is difficult to apply to new energy vehicles or energy storage power station such as power battery,

[0005] Chinese patent CN112457822A proposes a cooling liquid with ethylene glycol and deionized water as the main body, adding a certain amount of heat-conducting powder, surfactant and defoaming agent. The heat-conducting powder is a mixture of one or more of TiO2, Al2O3 and ZnO to achieve better heat-conducting performance. However, the addition of other powders will cause the electrical conductivity not to meet the requirements of fuel cell cooling liquid, and the addition of powders will also pose new challenges to the corrosion resistance of the cooling system metal, the cleanliness of the pipeline and the service life of the cooling liquid. Although this patent solves the technical problems of low electrical conductivity and high heat transfer coefficient, the main problem is that the electrical conductivity and the retention of electrical conductivity determine that it cannot be used as a direct contact power battery liquid cooling medium and must be used with a liquid cooling plate. Similarly, US patent US8187763B discloses a coolant composition for fuel cell units, which also has problems of electrical conductivity and retention of electrical conductivity, and cannot be directly used as an immersion cooling liquid for power batteries.

[0006] Therefore, according to the requirements of safe operation, long service life, efficient storage and release of electric energy and other requirements of power batteries in new energy vehicles and energy storage power stations, it is necessary to develop a high-efficiency heat-conducting, anti-freezing and insulating cooling liquid for use in the immersion liquid cooling system of new energy vehicles and energy storage power stations. SUMMARY

[0007] In view of the deficiencies of the prior art, the purpose of the present application is to provide a lithium ion battery immersion cooling liquid with excellent anti-freezing, heat-conducting, insulating and low-temperature flow properties.

[0008] To achieve this purpose, the present application adopts the following technical solutions:

[0009] A lithium ion battery immersion cooling liquid, characterized in that it is composed of propylene glycol, perfluorohexanone, dipropylene glycol methyl ether, defoaming agent, corrosion inhibitor and 2,6-di-tert-butyl-p-cresol, and the mass percentage of each component is: propylene glycol 45%-90%, perfluorohexanone 5%-50%, dipropylene glycol methyl ether 2%-15%, defoaming agent 0.0050%-0.02%, corrosion inhibitor 0.5%-5%, and 2,6-di-tert-butyl-p-cresol 0.1%-0.4%.

[0010] Preferably, the mass percentage of each component is: propylene glycol 50%-80%, perfluorohexanone 10%-40%, dipropylene glycol methyl ether 6%-12%, defoaming agent 0.0050%-0.02%, corrosion inhibitor 1.0%-3.5%, and 2,6-di-tert-butyl-p-cresol 0.1%-0.3%.

[0011] Further preferably, the mass percentage of each component is: propylene glycol 55%-76%, perfluorohexanone 12%-35%, dipropylene glycol methyl ether 6%-10%, antifoaming agent 0.0050%-0.02%, corrosion inhibitor 1.5%-2.5%, 2,6-di-tert-butyl-p-cresol 0.1%-0.2%.

[0012] Still further preferably, the mass ratio of propylene glycol, perfluorohexanone and dipropylene glycol methyl ether is 60:30:8.

[0013] Further, the antifoaming agent is one of block polyether and silicone antifoaming agent, and BASF PE6100 and Lianqingxin FOAM BAN 130B can be optionally used.

[0014] Further, the corrosion inhibitor is a conventional inorganic salt and organic carboxylic acid corrosion inhibitor such as sodium silicate, sebacic acid, isooctanoic acid, methyl benzotriazole, benzotriazole, sodium phosphate and sodium petroleum sulfonate.

[0015] The conductivity of the lithium ion battery immersion coolant obtained by the present application is ≤1 μS / cm, the latent heat of phase change is 6-50 kJ / kg, and the heat transfer coefficient is ≥0.2177 W / (m·K).

[0016] The lithium ion battery immersion coolant of the present application is compounded by a freezing-proof carrier such as propylene glycol, a phase change material such as perfluorohexanone, a corrosion inhibitor, 2,6-di-tert-butyl-p-cresol and an antifoaming agent. The freezing-proof carrier provides freezing-proof performance and flow channels for the phase change material, and drives the phase change material to absorb and release heat at a specified position. The freezing-proof carrier and the phase change material together provide heat transfer, and the phase change material can efficiently exchange heat, thus providing excellent cooling effect. The selected material of the phase change material is low in conductivity, and thus can be directly contacted with the charged part, thus providing higher heat transfer performance. The selected antifoaming agent reduces the foaming ability of the coolant base liquid, and improves the ability to inhibit foam, thus providing a basis for normal circulation of the coolant. 2,6-di-tert-butyl-p-cresol blocks the reaction of alcohol radical and blocks the oxidation of alcohol. The addition of the corrosion inhibitor can form an adsorption film or a precipitate film with the metal parts of the thermal management system, thus effectively preventing corrosion of the metal parts. The formula system of the present application is synergistic with each component, and finally obtains a lithium battery immersion coolant with excellent freezing-proof, heat transfer and insulation, which is especially suitable for the immersion cooling mode of lithium ion batteries, and can be applied to the temperature control system of new energy vehicles and lithium ion energy storage power stations.

[0017] Compared with the prior art, the lithium ion battery immersion coolant of the present application has excellent freezing-proof, heat transfer, insulation and low temperature flowability. The beneficial effects of the present application are embodied in the following aspects:

[0018] 1. Excellent anti-freezing performance, solves the anti-freezing problem during the operation stop of new energy vehicles and lithium ion energy storage power stations, and excellent low temperature fluidity.

[0019] 2. Excellent heat transfer performance, heat is transferred through the phase change of the phase change material, and the lithium ion battery can be directly contacted with the heat generating lithium ion battery, further increasing the temperature control uniformity and safety of the lithium ion battery pack.

[0020] 3. Excellent insulation performance, can be directly contacted with the positive and negative electrodes of the lithium ion battery, and meets the technical requirements of immersion liquid cooling.

[0021] 4. Excellent cost performance, greatly reduces the cost of immersion liquid cooling medium, and is suitable for large-scale popularization and application compared with fluorine fluid. DETAILED DESCRIPTION

[0022] The preferred embodiments of the present application will be described in detail below with reference to the examples. It should be understood that the following examples are given only for the purpose of illustration and are not intended to limit the scope of the present application. Those skilled in the art can make various modifications and substitutions to the present application without departing from the spirit and principles of the present application.

[0023] The materials, reagents, etc. used in the following examples, unless otherwise specified, can be obtained commercially.

[0024] The defoaming agent used in the following examples is an organic silicon defoaming agent, specifically selected as Lianqingxin FOAM BAN 130B.

[0025] Example 1

[0026] The present embodiment provides a lithium ion battery immersion cooling liquid, the mass percentage of each component is: propylene glycol 45%, perfluorohexanone 50%, dipropylene glycol methyl ether 4.04%, defoaming agent 0.01%, sebacic acid 0.05%, sodium silicate 0.2%, methyl benzotriazole 0.5%, 2,6-di-tert-butyl-p-cresol 0.2%. Each component is uniformly stirred, and then filtered with deionized resin to obtain the lithium ion battery immersion cooling liquid.

[0027] Example 2

[0028] The present embodiment provides a lithium ion battery immersion cooling liquid, the mass percentage of each component is: propylene glycol 90%, perfluorohexanone 5%, dipropylene glycol methyl ether 4.04%, defoaming agent 0.01%, sebacic acid 0.05%, sodium silicate 0.2%, methyl benzotriazole 0.5%, 2,6-di-tert-butyl-p-cresol 0.2%. Each component is uniformly stirred, and then filtered with deionized resin to obtain the lithium ion battery immersion cooling liquid.

[0029] Example 3

[0030] The present example provides a kind of lithium ion battery immersion type cooling liquid, the mass percentage of each component is: propylene glycol 65%, perfluorohexanone 30%, dipropylene glycol methyl ether is 3%, antifoaming agent 0.01%, sebacic acid 0.3%, sodium silicate 0.24%, methyl benzotriazole 1.25%, 2,6-di-tert-butyl-p-cresol 0.2%.Each component is uniformly stirred conventionally, using deionization resin filtration, i.e. lithium ion battery immersion type cooling liquid is obtained.

[0031] Example 4

[0032] The present example provides a kind of lithium ion battery immersion type cooling liquid, the mass percentage of each component is: propylene glycol 50%, perfluorohexanone 45%, dipropylene glycol methyl ether is 3%, antifoaming agent 0.01%, sebacic acid 0.3%, sodium silicate 0.24%, methyl benzotriazole 1.25%, 2,6-di-tert-butyl-p-cresol 0.2%.Each component is uniformly stirred conventionally, using deionization resin filtration, i.e. lithium ion battery immersion type cooling liquid is obtained.

[0033] Example 5

[0034] The present example provides a kind of lithium ion battery immersion type cooling liquid, the mass percentage of each component is: propylene glycol 60%, perfluorohexanone 28%, dipropylene glycol methyl ether is 10%, antifoaming agent is 0.01%, sebacic acid 0.3%, sodium silicate 0.24%, methyl benzotriazole 1.25%, 2,6-di-tert-butyl-p-cresol 0.2%.Each component is uniformly stirred conventionally, using deionization resin filtration, i.e. lithium ion battery immersion type cooling liquid is obtained.

[0035] Example 6

[0036] The present example provides a kind of lithium ion battery immersion type cooling liquid, the mass percentage of each component is: propylene glycol 60%, perfluorohexanone 30%, dipropylene glycol methyl ether is 8%, antifoaming agent is 0.01%, sebacic acid 0.3%, sodium silicate 0.24%, methyl benzotriazole 1.25%, 2,6-di-tert-butyl-p-cresol 0.2%.Each component is uniformly stirred conventionally, using deionization resin filtration, i.e. lithium ion battery immersion type cooling liquid is obtained.

[0037] Comparative Example 1

[0038] The cooling liquid of the present comparative example does not contain perfluorohexanone and dipropylene glycol methyl ether, and the mass percentage of each component is: propylene glycol 95%, sebacic acid 2%, sodium silicate 2%, methyl benzotriazole 1%.

[0039] Comparative Example 2

[0040] The cooling liquid of the present comparative example does not contain dipropylene glycol methyl ether, and the mass percentage of each component is: 66% of propylene glycol, 32% of perfluorohexanone, 0.01% of defoaming agent, 0.3% of sebacic acid, 0.24% of sodium silicate, 1.25% of methyl benzotriazole, and 0.2% of 2,6-di-tert-butyl-p-cresol.

[0041] Comparative Example 3

[0042] The cooling liquid of the present comparative example does not contain perfluorohexanone, and the mass percentage of each component is: 90% of propylene glycol, 8% of dipropylene glycol methyl ether, 0.01% of defoaming agent, 0.3% of sebacic acid, 0.24% of sodium silicate, 1.25% of methyl benzotriazole, and 0.2% of 2,6-di-tert-butyl-p-cresol.

[0043] Comparative Example 4

[0044] The present comparative example is Example 3 in Chinese Patent CN112708398A.

[0045] The lithium ion battery immersion cooling liquids prepared according to Examples 1-6 and the cooling liquids prepared according to Comparative Examples 1-4 were subjected to performance tests. The freezing point of the solutions of the examples and comparative examples was tested according to SH / T 0090 “Method for Determining the Freezing Point of Engine Coolant” to reflect the antifreeze performance; the thermal conductivity was tested according to ASTM D7896 “Standard Test Method for Thermal Conductivity, Thermal Diffusivity, and Volumetric Heat Capacity of Engine Coolants and Related Fluids Using the Transient Hot-Wire Liquid Heat Transfer Method” to reflect the heat transfer performance; the latent heat of phase transition was measured by differential scanning calorimetry (DSC) to reflect the heat transfer performance; the electrical conductivity was tested according to GB / T 6682 “Water for Analytical Laboratory: Specifications and Test Methods” to reflect the insulation performance; and the dynamic viscosity (0°C) was tested according to GB / T 265 “Determination of Kinematic Viscosity and Calculation of Dynamic Viscosity” to reflect the low-temperature flowability, and the specific test results are shown in Table 1.

[0046] Table 1 Performance test results of the cooling liquids of Examples 1-6 and Comparative Examples 1-4

[0047] Test item Conductivity, μs / cm Freezing point, °C Thermal conductivity, W / (m·K) Latent heat of phase transition, kJ / kg Kinetic viscosity (0°C), mPa·s Example 1 0.5 ＜-50 0.3256 50 90.51 Example 2 0.1 ＜-50 0.2381 5.6 180.4 Example 3 0.2 ＜-50 0.3612 33.6 154.6 Example 4 0.3 ＜-50 0.5123 49.6 90.56 Example 5 0.1 ＜-50 0.4243 31.6 50.61 Example 6 0.8 ＜-50 0.4387 33.8 60.30 Comparative Example 1 0.6 ＜-50 0.2068 None 244.6 Comparative Example 2 0.3 ＜-50 0.3257 35.8 240.6 Comparative Example 3 0.4 ＜-50 0.2002 None 106.9 Comparative Example 4 0.8 ＞0 0.3835 36.5 260.1

[0048] Examples 1-6 all have good antifreeze performance, heat transfer performance, and low-temperature flowability, and considering comprehensively, the comprehensive performance of Example 6 is the most excellent in terms of antifreeze performance, heat transfer performance, and low-temperature flowability. Comparative Examples 1 and 3 have no latent heat of phase transition during flow, resulting in a decrease in heat transfer performance, and the dynamic viscosity (0°C) of Comparative Example 1 is 244.6 mPa·s, which is poor in low-temperature flowability. Comparative Example 4 has excellent heat transfer performance, but its freezing point is 0°C, which has no antifreeze performance, and its dynamic viscosity (0°C) reaches 260.1 mPa·s, which is poor in low-temperature flowability. Comparative Example 2 has excellent antifreeze performance and heat transfer performance, but it is poor in low-temperature flowability.

[0049] The lithium ion battery immersion coolant has excellent high-efficiency heat transfer, antifreezing, insulation, low-temperature fluidity and the like, is suitable for new energy vehicle and energy storage power station immersion liquid cooling systems, has low cost and can be widely applied.

[0050] It should be noted that the above-described embodiments are merely intended for the explanation of the present application and do not constitute any limitation of the present application. The present application has been described by referring to typical embodiments, but it should be understood that the words used therein are descriptive and explanatory words, rather than limiting words. The present application can be modified within the scope of the claims of the present application, and the present application can be revised within the scope and spirit of the present application. Although the present application described therein relates to specific methods, materials and embodiments, it does not mean that the present application is limited to the specific examples disclosed therein, but rather, the present application can be extended to all other methods and applications having the same function.

Claims

1. A lithium-ion battery immersion coolant, characterized by, Consist of propylene glycol, perfluorohexanone, dipropylene glycol methyl ether, defoaming agent, corrosion inhibitor and 2,6-di-tert-butyl-p-cresol, the mass percentage of each component is: propylene glycol 50%-80%, perfluorohexanone 10%-40%, dipropylene glycol methyl ether 6%-12%, defoaming agent 0.0050%-0.02%, corrosion inhibitor 1.0%-3.5%, 2,6-di-tert-butyl-p-cresol 0.1%-0.3%.

2. The lithium-ion battery immersion coolant of claim 1, wherein, The mass percentage of each component is: propylene glycol 55%-76%, perfluorohexanone 12%-35%, dipropylene glycol methyl ether 6%-10%, defoaming agent 0.0050%-0.02%, corrosion inhibitor 1.5%-2.5%, 2,6-di-tert-butyl-p-cresol 0.1%-0.2%.

3. The lithium-ion battery immersion coolant of claim 1, wherein: The defoaming agent is one of block polyether and silicone defoaming agent.

4. The lithium-ion battery immersion coolant of claim 1, wherein: The corrosion inhibitor is one or more of sodium silicate, sebacic acid, isooctanoic acid, methyl benzotriazole, benzotriazole, sodium phosphate and petroleum sulfonate sodium.

5. The lithium-ion battery immersion coolant of claim 1, wherein: The mass ratio of propylene glycol, perfluorohexanone and dipropylene glycol methyl ether is 60:30:

8.

6. The lithium-ion battery immersion coolant of any one of claims 1-5, wherein: The conductivity of the cooling liquid is ≤1 μS / cm.

7. The lithium-ion battery immersion coolant of any one of claims 1-5, wherein: The latent heat of phase transition of the cooling liquid is 6 kJ / kg-50 kJ / kg 8. The lithium-ion battery immersion coolant of any one of claims 1-5, wherein: The heat transfer coefficient of the cooling liquid is ≥0.2177 W / (m·K).