Flame retardant and preparation method thereof, flame-retardant cooling liquid and immersed energy storage device

Abstract

The invention discloses a flame retardant and a preparation method thereof, flame-retardant cooling liquid and an immersed energy storage device, the flame retardant has a chemical formula as shown in a formula 1, and in the formula 1, R is a C2-C5 alkyl chain. Therefore, the element B and the element P play a synergistic flame-retardant role, the flame-retardant efficiency of the flame retardant is improved, meanwhile, the element B has good heat conduction and heat transfer performance, the heat conductivity coefficient of a cooling liquid system is greatly improved through introduction of the element B, the heat transfer and heat dissipation effects are enhanced, and the application value of the cooling liquid is improved.

Description

Technical Field

[0001] This application relates to the field of energy storage safety technology, specifically to flame retardants and their preparation methods, flame retardant coolants, and submersible energy storage devices. Background Technology

[0002] Submerged energy storage technology can optimize the thermal management system of energy storage batteries, suppress battery thermal runaway, effectively solve battery thermal safety problems, improve the safety and cycle life of battery operation, and maintain the stability of the power grid system, which is of great significance to promoting the healthy and sustainable development of the new energy industry.

[0003] As the core of submerged energy storage technology, flame-retardant coolant directly affects the operating performance of submerged energy storage devices due to its thermophysical properties. The basic principles for selecting coolant mainly include: (1) high insulation performance to ensure non-conductivity; (2) excellent thermal conductivity to ensure timely heat dissipation; (3) excellent flame-retardant performance to prevent the spread of thermal runaway; (4) material compatibility to avoid corrosion of internal battery system materials; (5) environmental friendliness; and (6) wide temperature range performance to ensure good applicability in extremely cold or high temperature environments. However, existing coolants have poor flame retardancy and low thermal conductivity, resulting in poor heat transfer and dissipation effects.

[0004] It should be noted that the above statements are only used to provide background information related to this application and do not necessarily constitute prior art. Summary of the Invention

[0005] In a first aspect of this application, a flame retardant having the chemical formula shown in Formula 1 is provided. Formula 1, where R is a C2-C5 alkyl chain. Thus, element B and element P work synergistically to improve the flame retardant efficiency of the flame retardant. Simultaneously, element B has excellent thermal conductivity and heat transfer properties; the introduction of element B significantly increases the thermal conductivity of the coolant system, enhancing heat transfer and dissipation, and improving the application value of the coolant.

[0006] In some embodiments, the flame retardant includes Formula I Formula II Formula III At least one of Formula IV. Therefore, the aforementioned flame retardant exhibits good compatibility with base oils such as mineral oil and silicone oil, and also demonstrates good thermal conductivity and flame retardant properties.

[0007] In a second aspect, this application proposes a method for preparing a flame retardant, comprising: mixing a phosphate ester compound, boric acid, toluene, and a catalyst, followed by heating treatment, and then concentrating by rotary evaporation and purifying by chromatography to obtain the flame retardant. Therefore, the method provided by this application is simple, and the obtained flame retardant has the advantages of high thermal conductivity and good flame retardant performance, which is beneficial to improving the application value of coolants.

[0008] In some embodiments, the heat treatment is performed at a temperature of 70°C-120°C for 24-48 hours. This helps to increase the reaction rate and obtain a flame retardant with higher purity.

[0009] In some embodiments, the phosphate ester compound includes at least one selected from diethyl phosphate, dibutyl phosphate, dipentyl phosphate, and diisopentyl phosphate; and / or, the solvent includes at least one selected from toluene, benzene, pyridine, and 1,4-dioxane; and / or, the catalyst includes at least one selected from p-toluenesulfonic acid, methanesulfonic acid, trifluoromethanesulfonic acid, and phosphotungstic acid. Therefore, the raw materials are widely available and the cost is low.

[0010] In some embodiments, the mass ratio of the phosphate ester compound to the boric acid is 1:(1.2-1.5). This facilitates a more complete reaction and reduces raw material waste.

[0011] In a third aspect, this application proposes a flame-retardant coolant, comprising the flame retardant described in the first aspect or a flame retardant prepared using the method described in the second aspect. Therefore, this flame-retardant coolant not only possesses high flame-retardant efficiency but also good thermal conductivity, exhibits high safety performance, and has promising application prospects.

[0012] In some embodiments, the flame-retardant coolant comprises: 10-80 parts by weight of base oil and 20-90 parts by weight of the flame retardant. This improves the flame-retardant effect and heat transfer effect of the flame-retardant coolant.

[0013] In some embodiments, the base oil includes at least one selected from mineral oil, silicone oil, synthetic ester, and natural ester. Thus, the base oil, as the primary liquid carrier, provides fundamental protection for the insulating properties of the flame-retardant coolant.

[0014] In some embodiments, the mineral oil includes at least one of paraffinic oil and naphthenic oil; and / or, the silicone oil includes at least one of hydrogen-containing silicone oil, dimethyl silicone oil, and modified silicone oil; and / or, the synthetic ester includes at least one of polyol ester, diester, and phosphate ester; and / or, the natural ester includes at least one of plant-based ester oil, animal-based ester oil, and natural ester-modified oil. Thus, the base oil possesses certain insulating properties.

[0015] In a fourth aspect, this application proposes a submerged energy storage device comprising the flame-retardant coolant described in the third aspect. Because it employs the aforementioned flame-retardant coolant, the submerged energy storage device of this application possesses all the advantages of the flame-retardant coolant, which will not be elaborated further here.

[0016] In a fifth aspect, this application proposes a data center comprising the flame retardant described in the first aspect of this application or a flame retardant prepared using the method described in the second aspect of this application. Because of the use of the aforementioned flame retardant, the data center of this application possesses all the advantages of the flame retardant, which will not be elaborated further here.

[0017] In a sixth aspect, this application proposes an electrical appliance including the data center described in the fifth aspect. Due to the use of the aforementioned flame retardant, the electrical appliance of this application possesses all the advantages of the flame retardant, which will not be elaborated further here. Detailed Implementation

[0018] The embodiments of this application are described in detail below, but some unnecessary details may be omitted. For example, detailed descriptions of well-known matters may be omitted. This is to avoid making the following description unnecessarily lengthy and to facilitate understanding by those skilled in the art. Furthermore, the following description is provided to enable those skilled in the art to fully understand this application and is not intended to limit the subject matter of the claims.

[0019] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used in this application is for the purpose of describing particular embodiments only and is not intended to limit this application; unless otherwise stated, the values ​​of the parameters mentioned in this application can be measured using various measurement methods commonly used in the art (e.g., they can be tested according to the methods given in the embodiments of this application).

[0020] The terms “comprising” and “having”, and any variations thereof, in the specification and claims of this application are open-ended expressions, meaning they include what is specified in this application but do not exclude other aspects.

[0021] In the description of this application, all figures disclosed herein, whether or not the words "approximately" or "about" are used, are approximate values. Each figure may vary by less than 10% or by a difference that is considered reasonable by one of the art, such as 1%, 2%, 3%, 4%, or 5%.

[0022] The "range" disclosed in this application is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of a particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a specific parameter, it is expected that ranges of 60-110 and 80-120 are also included. Furthermore, if minimum range values ​​of 1 and 2 are listed, and if maximum range values ​​of 3, 4, and 5 are listed, then the following ranges are all expected: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5. In this application, unless otherwise stated, the numerical range "ab" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0-5" means that all real numbers between "0-5" have been listed in this article; "0-5" is just a shortened representation of these numerical combinations.

[0023] In the description of this application, "A and / or B" can include any of the cases of A alone, B alone, or A and B, where A and B are merely examples and can be any technical feature connected by "and / or" in this application.

[0024] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions.

[0025] Unless otherwise specified, all technical features and optional technical features of this application may be combined to form new technical solutions.

[0026] Coolants generally have low thermal conductivity. Mineral oils have a thermal conductivity of 0.12-0.14 W / (m·K), silicone oils 0.14-0.15 W / (m·K), ester-based insulating oils 0.16-0.17 W / (m·K), while fluorinated coolants have a thermal conductivity <0.1 W / (m·K). Therefore, improving the thermal conductivity of coolants and enhancing their heat dissipation performance is an important direction for coolant research and development.

[0027] In a first aspect of this application, a flame retardant having the chemical formula shown in Formula 1 is provided. Formula 1, where R is a C2-C5 alkyl chain. Thus, element B and element P work synergistically to improve the flame retardant efficiency of the flame retardant. Simultaneously, element B has excellent thermal conductivity and heat transfer properties; the introduction of element B significantly increases the thermal conductivity of the coolant system, enhancing heat transfer and dissipation, and improving the application value of the coolant.

[0028] Specifically, on the one hand, element B and element P play a synergistic flame-retardant role. During combustion, B releases B· and BH· free radicals into the gas phase to capture H· and HO· free radicals, generating boric acid, which quenches the combustion of the gas phase flame. The generated boric acid interacts with the phosphoric acid produced by P. Phosphoric acid promotes the dehydration of the matrix and forms a char layer, while boric acid further melts to form a glassy covering (B2O3) to strengthen the char layer. The two work together to build multiple efficient protective barriers in both the gas phase and the condensed phase, significantly improving the flame-retardant efficiency.

[0029] On the other hand, the introduction of boron (B) endows the coolant system with excellent thermal conductivity and heat transfer properties. The empty p orbitals of the B atom can undergo p-π conjugation with the O atoms in the phosphate ester group, enhancing the rigidity of the molecular skeleton and reducing the scattering of heat particles within the molecule. This allows heat particles to propagate more efficiently along the molecular chain, improving thermal conductivity. Furthermore, the B atom can act as a "cross-linking point," forming strong "molecular bridges." Through intermolecular interactions such as BOP bonds and strong hydrogen bonds, a stable three-dimensional transport network is built between adjacent molecules. This structure greatly promotes the transmolecular conduction of heat particles, thus exhibiting high thermal conductivity on a macroscopic scale. Therefore, the boron-containing phosphate ester flame retardant of this application not only achieves high flame retardant efficiency but also improves the thermal conductivity of the coolant system, increasing heat dissipation efficiency. This helps solve the problems of low flame retardant safety and poor heat transfer in traditional coolants, and has promising application prospects.

[0030] In some embodiments, the flame retardant includes Formula I Formula II Formula III At least one of Formula IV. Therefore, the aforementioned flame retardant exhibits good compatibility with base oils such as mineral oil and silicone oil, and also demonstrates good thermal conductivity and flame retardant properties.

[0031] In a second aspect, this application proposes a method for preparing a flame retardant, comprising: mixing a phosphate ester compound, boric acid, toluene, and a catalyst, followed by heating treatment, and then concentrating by rotary evaporation and purifying by chromatography to obtain the flame retardant. Therefore, the method provided by this application is simple, and the obtained flame retardant has the advantages of high thermal conductivity and good flame retardant performance, which is beneficial to improving the application value of coolants.

[0032] In some embodiments, the heat treatment temperature is 70℃-120℃ (e.g., 70℃, 80℃, 90℃, 100℃, 110℃, or 120℃), and the time is 24h-48h (e.g., 24h, 28h, 32h, 36h, 40h, 44h, or 48h). This is beneficial for increasing the reaction rate and obtaining a flame retardant with higher purity.

[0033] In some embodiments, the phosphate ester compound includes at least one selected from diethyl phosphate, dibutyl phosphate, dipentyl phosphate, and diisopentyl phosphate; and / or, the solvent includes at least one selected from toluene, benzene, pyridine, and 1,4-dioxane; and / or, the catalyst includes at least one selected from p-toluenesulfonic acid, methanesulfonic acid, trifluoromethanesulfonic acid, and phosphotungstic acid. Therefore, the raw materials are widely available and the cost is low.

[0034] In some embodiments, the mass ratio of the phosphate ester compound to the boric acid is 1:(1.2-1.5), for example, it can be 1:1.2, 1:1.3, 1:1.4, or 1:1.5. This helps to make the reaction more complete and reduce the waste of raw materials.

[0035] As an example, the reaction process can be as follows: using toluene as the reaction solvent, 1 mol of a phosphate ester compound and 1.1 mol of boric acid are placed in a reactor, and 0.1 mol of p-toluenesulfonic acid (TsOH) is added as a catalyst. The reaction is carried out at 70°C for 24 hours. After the reaction is completed, the mixture is concentrated by rotary evaporation and purified by chromatography to obtain a boron-containing phosphate ester flame retardant. The reaction process is shown below:

[0036] Specifically, when the phosphate compound is diethyl phosphate ( When the reaction occurs, the flame retardant shown in Formula I is obtained; When the phosphate compound is dibutyl phosphate ( When the reaction occurs, the flame retardant shown in Formula II is obtained; When the phosphate compound is dipentyl phosphate, the reaction yields the flame retardant shown in Formula III; When the phosphate compound is diisoamyl phosphate, the reaction yields the flame retardant shown in Formula IV.

[0037] In a third aspect, this application proposes a flame-retardant coolant, comprising the flame retardant described in the first aspect or a flame retardant prepared using the method described in the second aspect. Therefore, this flame-retardant coolant not only possesses high flame-retardant efficiency but also good thermal conductivity, exhibits high safety performance, and has promising application prospects.

[0038] In some embodiments, the flame-retardant coolant comprises: 10-80 parts by weight of base oil and 20-90 parts by weight of the flame retardant. This improves the flame-retardant effect and heat transfer effect of the flame-retardant coolant.

[0039] As an example, the base oil can be 10 parts by weight, 20 parts by weight, 30 parts by weight, 40 parts by weight, 50 parts by weight, 60 parts by weight, 70 parts by weight, or 80 parts by weight, etc., and the flame retardant can be 20 parts by weight, 30 parts by weight, 40 parts by weight, 50 parts by weight, 60 parts by weight, 70 parts by weight, 80 parts by weight, or 90 parts by weight, etc.

[0040] In some embodiments, the base oil includes at least one selected from mineral oil, silicone oil, synthetic ester, and natural ester. Thus, the base oil, as the primary liquid carrier, provides fundamental protection for the insulating properties of the flame-retardant coolant.

[0041] In some embodiments, the mineral oil includes at least one of paraffinic oil and naphthenic oil; and / or, the silicone oil includes at least one of hydrogen-containing silicone oil, dimethyl silicone oil, and modified silicone oil; and / or, the synthetic ester includes at least one of polyol ester, diester, and phosphate ester; and / or, the natural ester includes at least one of plant-based ester oil, animal-based ester oil, and natural ester-modified oil. Thus, the base oil possesses certain insulating properties.

[0042] In some embodiments, the mineral oil includes at least one of mineral oil No. 10, mineral oil No. 25, and mineral oil No. 45.

[0043] In some embodiments, the modified silicone oil includes at least one of amino-modified silicone oil, hydroxyl-modified silicone oil, epoxy-modified silicone oil, long-chain alkane-modified silicone oil, olefin-modified silicone oil, and fluorinated modified silicone oil.

[0044] In some embodiments, the polyol ester includes at least one of pentaerythritol oleate, pentaerythritol tetraoctanoate, pentaerythritol tetradecanoate, dipentaerythritol hexanonanoate, trimethylolpropane oleate, trimethylolpropane trioctanoate, trimethylolpropane tridecanoate, neopentyl glycol diheptanoate, neopentyl glycol didecanoate, and neopentyl glycol dioctanoate; and / or, the diester includes at least one of dibutyl adipate, diisooctyl adipate, diisodecyl adipate, di(2-ethylhexyl) adipate, diisooctyl azelate, diisooctyl sebacate, di(2-ethylhexyl) sebacate, and diisooctyl azelate; and / or, the phosphate ester includes at least one of trioctyl phosphate, tributyl phosphate, tri(2-ethylhexyl) phosphate, hexadecyl phosphate, and glycerophosphate.

[0045] In some embodiments, the plant-based ester oil includes at least one selected from soybean oil, rapeseed oil, sunflower seed oil, palm oil, and castor oil; and / or, the animal-based ester oil includes at least one selected from beef hoof oil, tallow, and lard; and / or, the natural ester-modified oil includes at least one selected from rapeseed oil methyl ester, soybean oil methyl ester, palm oil methyl ester, epoxidized soybean oil, epoxidized linseed oil, and tallow methyl ester; and / or, the natural ester includes at least one selected from olive oil, peanut oil, soybean oil, corn oil, sunflower seed oil, and palm oil. Therefore, the base oil sources are wide-ranging, offering a broad selection and facilitating large-scale promotion.

[0046] As an example, a method for preparing a flame-retardant coolant includes mixing the base oil and the flame retardant to obtain the flame-retardant coolant.

[0047] In some embodiments, the mixing temperature is 40°C-60°C, for example, 40°C, 45°C, 50°C, 55°C, or 60°C. This facilitates uniform mixing of the components in the flame-retardant coolant, forming a homogeneous system and preventing performance degradation caused by uneven mixing.

[0048] In some embodiments, the mixing is carried out under stirring at a speed of 600 r / min to 1000 r / min, such as 600 r / min, 700 r / min, 800 r / min, 900 r / min, or 1000 r / min. This application does not impose any special limitation on the mixing method; other commonly used methods can also be used.

[0049] In some embodiments, the mixing time is 1 hour to 5 hours, for example, 1 hour, 2 hours, 3 hours, 4 hours, or 5 hours. A mixing time within this range allows the base oil and flame retardant to mix thoroughly, promoting uniform dispersion of the flame retardant in the base oil.

[0050] In a fourth aspect, this application proposes a submerged energy storage device comprising the flame-retardant coolant described in the third aspect. Because it employs the aforementioned flame-retardant coolant, the submerged energy storage device of this application possesses all the advantages of the flame-retardant coolant, which will not be elaborated further here.

[0051] In some embodiments, the submersible energy storage device includes a housing, an energy storage structure disposed within the housing, and a flame-retardant coolant filled within the housing.

[0052] In a fifth aspect, this application proposes a data center comprising the flame retardant described in the first aspect of this application or a flame retardant prepared using the method described in the second aspect of this application. Because of the use of the aforementioned flame retardant, the data center of this application possesses all the advantages of the flame retardant, which will not be elaborated further here.

[0053] In some embodiments, the data center is a physical facility designed for centralized storage, processing, and exchange of data, including servers, storage devices, network equipment, and supporting systems (such as power supply systems, cooling systems, etc.), and is a core infrastructure for cloud computing and internet services. The cooling system may include the aforementioned flame-retardant coolant for server heat dissipation.

[0054] In a sixth aspect, this application proposes an electrical appliance including the data center described in the fifth aspect. Due to the use of the aforementioned flame retardant, the electrical appliance of this application possesses all the advantages of the flame retardant, which will not be elaborated further here.

[0055] The description of the various embodiments above tends to emphasize the differences between the various embodiments. The similarities or similarities between them can be referred to, and for the sake of brevity, they will not be repeated here.

[0056] The following specific embodiments illustrate the solution of this application. It should be noted that these embodiments are for illustrative purposes only and should not be considered as limiting the scope of this application. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in this field or according to the product instructions. Reagents or instruments whose manufacturers are not specified are all conventional products that can be obtained commercially.

[0057] Example 1 Weigh 80 parts by weight of No. 25 mineral oil and 20 parts by weight of flame retardant with the structure shown in Formula I, and mix them at 45℃ and 800r / min for 2 hours to obtain flame retardant coolant.

[0058] Example 2 Weigh 10 parts by weight of No. 25 mineral oil and 90 parts by weight of flame retardant with the structure shown in Formula I, and mix them at 45℃ and 800r / min for 2 hours to obtain flame retardant coolant.

[0059] Example 3 Weigh 60 parts by weight of No. 25 mineral oil and 40 parts by weight of flame retardant with the structure shown in Formula I, and mix them at 45℃ and 800r / min for 2 hours to obtain flame retardant coolant.

[0060] Example 4 Weigh 60 parts by weight of No. 25 mineral oil and 40 parts by weight of flame retardant with the structure shown in Formula II, and mix them at 45℃ and 800r / min for 2 hours to obtain flame retardant coolant.

[0061] Example 5 Weigh 60 parts by mass of dimethyl silicone oil and 40 parts by mass of flame retardant having the structure shown in Formula I, and mix them at 45°C and 800 r / min for 2 hours to obtain flame retardant coolant.

[0062] Example 6 Weigh 60 parts by mass of trioctyl phosphate and 40 parts by mass of a flame retardant having the structure shown in Formula I, and mix them at 45°C and 800 r / min for 2 hours to obtain a flame-retardant coolant.

[0063] Comparative Example 1 Weigh 80 parts by weight of No. 25 mineral oil and 20 parts by weight of diethyl phosphate, and mix them at 45℃ and 800r / min for 2 hours to obtain a flame-retardant coolant.

[0064] Comparative Example 2 Weigh 80 parts by weight of No. 25 mineral oil and 20 parts by weight of dibutyl phosphate, and mix them at 45℃ and 800r / min for 2 hours to obtain a flame-retardant coolant.

[0065] Comparative Example 3 Weigh 80 parts by weight of No. 25 mineral oil, 10 parts by weight of diethyl phosphate, and 10 parts by weight of boric acid, and mix them at 45℃ and 800r / min for 2 hours to obtain a flame-retardant coolant.

[0066] The flame-retardant coolants obtained in the above embodiments and comparative examples were tested for insulation and safety performance, and the results are shown in Table 1.

[0067] Physicochemical performance testing: Thermal conductivity and breakdown voltage were tested on the examples and comparative samples according to the test methods in ASTM D7896 and GB / T 507. Safety performance test: Five 100% SOC battery cells (rated capacity 45Ah, operating voltage range 2.5V-4.2V) were placed in a cell holder in series to simulate a five-cell series module. The middle cell was overcharged, and the module was externally fixed with a clamp. The module was immersed in coolant. After setting, it was continuously charged at 1C until overcharging triggered thermal runaway. Charging was then stopped, and the flame-retardant coolant was observed to prevent combustion and explosion.

[0068] Table 1

[0069] As can be seen from Table 1, compared with the coolants of Comparative Examples 1-3, the flame-retardant coolants of Examples 1-6 have lower thermal conductivity and better insulation and flame-retardant properties.

[0070] It should be noted that this application is not limited to the above-described embodiments. The above embodiments are merely examples, and any embodiments with the same structure and effect as the technical concept within the scope of this application are included in the technical scope of this application. Furthermore, various modifications that can be conceived by those skilled in the art to the embodiments, and other ways of constructing by combining some of the constituent elements of the embodiments, without departing from the spirit of this application, are also included in the scope of this application.

Claims

1. A flame retardant, characterized in that, A chemical formula shown in Formula 1, Formula 1, wherein R is a C2-C5 alkyl chain.

2. The flame retardant according to claim 1, characterized in that The flame retardant includes at least one of Formula I, at least one of Formula II, at least one of Formula III, at least one of Formula IV.

3. A process for the preparation of a flame retardant according to any one of claims 1-2, characterized in that, The application relates to a flame retardant and a preparation method thereof. The phosphate compound, the boric acid, the solvent and the catalyst are mixed and heated, concentrated by rotary evaporation and purified by chromatography to obtain the flame retardant.

4. The method of claim 3, wherein, The heating temperature is 70-120 DEG C and the heating time is 24-48 hours.

5. The method of claim 3, wherein, The phosphate compound comprises at least one of diethyl phosphate, dibutyl phosphate, dipentyl phosphate and diisopentyl phosphate; and / or, The solvent comprises at least one of toluene, benzene, pyridine and 1,4-dioxane; and / or, The catalyst comprises at least one of p-toluenesulfonic acid, methanesulfonic acid, trifluoromethanesulfonic acid and phosphotungstic acid.

6. The method of claim 3, wherein, The mass ratio of the phosphate compound to the boric acid is 1:(1.2-1.5).

7. A fire-retardant coolant fluid, characterized in that, The application further relates to a flame retardant prepared by the method.

8. The fire resistant coolant fluid of claim 7, wherein, The application relates to a flame retardant and a preparation method thereof. 10-80 parts by mass of base oil and 20-90 parts by mass of the flame retardant.

9. The fire resistant coolant fluid of claim 8, wherein, The base oil comprises at least one of mineral oil, silicone oil, synthetic ester and natural ester.

10. The fire resistant coolant fluid of claim 9, wherein, The mineral oil comprises at least one of paraffin base oil and naphthenic base oil; and / or, The silicone oil comprises at least one of hydrogen-containing silicone oil, dimethyl silicone oil and modified silicone oil; and / or, The synthetic ester comprises at least one of polyol ester, diester and phosphate ester; and / or, The natural ester comprises at least one of plant-based ester oil, animal-based ester oil and natural ester modified oil.

11. An immersed energy storage device, characterized by, The application further relates to a flame retardant coolant.

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