Cooling liquid for fuel cell and preparation method thereof

Abstract

The invention discloses a cooling liquid for a fuel cell and a preparation method of the cooling liquid. The cooling liquid comprises 40 to 55.5 wt% of deionized water, 35 to 50 wt% of amino acid salt, 0.5 to 5 wt% of dioctyl azelate, 0.1 to 0.2 wt% of a buffer agent, 0.2 to 0.4 wt% of tributyl phosphate, 0.8 to 1.1 wt% of acrylic ester, 1.2 to 3.6 wt% of a nonionic metal inhibitor and 1.6 to 4.8 wt% of a heat conduction additive, the technical problems that an existing cooling liquid for the fuel cell is poor in heat transfer, corrosion resistance and durability can be solved. And the preparation method adopts a conventional method, so that the preparation difficulty and the operation difficulty of operators are greatly reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of fuel cells, and specifically relates to a coolant for fuel cells and a preparation method thereof. Background Art

[0002] With the continuous growth of global energy demand and the improvement of environmental protection awareness, fuel cells, as an efficient and clean energy conversion device, have received extensive attention and research. Fuel cells directly generate electricity through the chemical reaction of hydrogen and oxygen, and have the advantages of high energy conversion efficiency and low environmental pollution. However, fuel cells generate a lot of heat during operation. If the heat cannot be dissipated in time and effectively, the battery temperature will be too high, affecting its performance and life. Therefore, the development of efficient cooling systems and coolants has become an important direction for the development of fuel cell technology.

[0003] Traditional coolants are mostly a mixture of water and ethylene glycol. Although they have good thermal stability and antifreeze properties, they have limited heat transfer efficiency under high heat loads and are difficult to meet the heat dissipation requirements of high-performance fuel cells. In addition, traditional coolants are prone to corrosion and increased conductivity during long-term use, which will further affect the performance and life of the fuel cell.

[0004] Therefore, developing a fuel cell coolant with high thermal conductivity can not only improve the thermal management performance of the fuel cell, but also extend its service life, which is of great practical significance. Summary of the invention

[0005] In order to overcome the defects of the prior art, the present invention provides a fuel cell coolant and a preparation method thereof, which can solve the technical problems of poor heat transfer and thermal conductivity, high electrical conductivity, poor corrosion resistance and poor durability of the current fuel cell coolant.

[0006] The object of the present invention is achieved through the following technical solutions: In a first aspect, the present invention provides a coolant for a fuel cell, comprising the following raw materials: Deionized water 40~55.5 wt%, amino acid salt 35~50 wt%, dioctyl azelate 0.5~5 wt%, buffer 0.1~0.2 wt%, tributyl phosphate 0.2~0.4 wt%, acrylate 0.8~1.1 wt%, non-ionic metal inhibitor 1.2~3.6wt%, thermal conductive additive 1.6~4.8 wt%.

[0007] The main beneficial effects of the present invention are as follows: The main beneficial effects of each component in the present invention are as follows: Deionized water: solvent, used as dispersion medium; it has the highest specific heat capacity and absorbs the most heat per unit mass.

[0008] Amino acid salt: antifreeze agent, used to lower the freezing point of water and prevent the liquid in the cooling system from freezing in low temperature environments.

[0009] Acrylate: Antifreeze agent, corrosion inhibitor, contains numerous alkyl and polar groups, which can prevent water molecules from combining to form ice crystals, thereby preventing water from freezing. In addition, acrylate can slow down metal corrosion.

[0010] Dioctyl Azelate: Plasticizer, reduces the glass transition temperature of the coolant and the viscosity of the system, ensuring that the coolant can maintain better performance and stability when facing various temperature and pressure changes. It has low viscosity, high boiling point, high plasticizing efficiency, low water extraction, low volatility and migration, and has excellent heat resistance, light resistance, electrical insulation and viscosity stability of plasticized paste.

[0011] Buffer: adjust and stabilize the pH of the system.

[0012] Tributyl phosphate: defoaming agent. Tributyl phosphate can reduce the surface tension of liquids and prevent the formation of foam, thereby effectively eliminating the foam that has already formed; the specific mechanism of action is to reduce the surface tension of water, solution, etc., prevent the formation of foam, and reduce or eliminate the original foam. It can make the film of the formed foam unstable, thereby quickly eliminating the foam. In addition, tributyl phosphate is also resistant to high temperature, acid and alkali, and can stably perform the defoaming function under high temperature, high pressure, strong acid and strong alkali environment. It has good water solubility and permeability, and can quickly penetrate into the foam, destroy the stability of the foam, and achieve the purpose of defoaming.

[0013] Non-ionic metal inhibitors: inhibit or reduce the generation of metal ions and reduce the conductivity of the system.

[0014] Thermally conductive additive: A high thermally conductive composite material is used to improve the thermal conductivity of the system, wherein the thermally conductive additive is prepared by one of electrochemical deposition, chemical vapor deposition, sol-gel method, and hydrothermal method.

[0015] The specific selection method is as follows: The above-mentioned nonionic metal inhibitor, thermal conductive additive and dioctyl azelate can play a synergistic role with each other, which can further enhance the thermal conductive effect of the thermal conductive additive and dioctyl azelate, and dioctyl azelate can also assist in reducing the conductivity of the overall system, but does not affect the conductivity of the internal thermal conductive additive; and acrylates and amino acid salts can further play a synergistic role, thereby improving the cooling effect of the coolant; acrylates, amino acid salts, metal inhibitors, thermal conductive additives and dioctyl azelate can also work together to play a synergistic effect of cooling and heat conduction, and the cooling capacity and thermal conductivity of the prepared coolant are further improved. In one embodiment, the buffer includes at least one of sodium tripolyphosphate, disodium hydrogen phosphate, and sodium phosphate.

[0016] The main beneficial effects of the present invention are as follows: the buffer can help absorb or release hydrogen ions (H+), thereby maintaining the pH value of the coolant within a relatively stable range, preventing damage to the fuel cell components due to excessive changes in the pH value; the appropriate pH value can reduce the risk of corrosion of metal parts and the risk of increased conductivity of the coolant. If the pH value of the coolant is too low or too high, it may accelerate the corrosion process of metal parts, affecting the long-term performance and life of the fuel cell, and may promote the precipitation of other anions and cations, resulting in an increase in the conductivity of the coolant. The buffer slows down this corrosion and stabilizes the conductivity of the system by maintaining a suitable pH value; the sealing materials (such as rubber, etc.) used in fuel cells also have specific requirements for pH values. The buffer helps keep these materials in good working condition and avoids the problem of sealing failure caused by unstable pH values.

[0017] In one embodiment, the nonionic metal inhibitor includes at least one of ethylenediaminetetraacetic acid, hydroxyethylenediphosphonate, benzotriazole, benzothiophene, and benzothiopyridine.

[0018] The main beneficial effects of the present invention are as follows: the non-ionic metal inhibitor can not only prevent the corrosive medium from directly contacting the metal surface and thus prevent metal corrosion, but also improve the heat transfer efficiency of the coolant and thus improve the cooling effect.

[0019] In one embodiment, the thermal conductive additive includes an outer layer and an inner layer, the outer layer completely covers the inner layer, the outer layer is Al2O3 or CuO, and the inner layer includes perovskite oxide and at least one of reduced graphene, graphite, and perovskite oxide-graphene.

[0020] The outer layer is metal oxide, while the inner layer is mainly conductive material. The outer metal oxide mainly plays a cooling role and reduces the conductivity of the thermal conductive additive. Aluminum oxide and copper oxide have a relatively ordered lattice, can play a better cooling role and have a lower conductivity, and will not cause the introduction of thermal conductive agents to increase the conductivity of the coolant; the internal conductive material has good cooling performance and can further play a cooling role.

[0021] In one embodiment, the inner layer and the outer layer constitute a sphere and / or a tube bundle structure of a core-shell structure.

[0022] The spherical structure and the tube bundle structure can increase the specific surface area of ​​the exterior of the heat-conducting additive, thereby increasing the contact area between the fuel cell and the coolant, and further improving the cooling effect.

[0023] In one embodiment, the perovskite oxide includes at least one of lanthanum nickelate, lanthanum cobalt nickelate, and lanthanum strontium cobalt iron.

[0024] Lanthanum nickelate, lanthanum cobalt nickelate and lanthanum strontium cobalt iron are all metal oxides with complex structures and multiple properties. Among them, lanthanum nickelate and lanthanum cobalt nickelate have good thermal stability and will not cause thermal decomposition of the overall fixed material due to the high heat emitted by the fuel cell. Lanthanum nickelate and lanthanum strontium cobalt iron have good thermoelectric properties and can convert part of the heat emitted by the fuel cell into electrical energy, thereby providing a certain amount of energy for the fuel cell.

[0025] In one embodiment, the chemical formula of the lanthanum cobalt nickelate is LaNixCoyO3, wherein 0≤x≤0.5, 0≤y≤1; the chemical formula of the lanthanum strontium cobalt iron is La0.6Sr0.4Co(1-y2)Fey2O3, wherein 0≤y2≤1.

[0026] The values ​​of x, y, and y2 can ensure that the obtained thermally conductive solid material has excellent electrical and thermal conductivity. The external aluminum oxide and copper oxide can prevent the internal conductive material from affecting the conductive properties of the coolant due to their insulating properties. The internal conductive material can further assist in thermal conduction due to its conductive properties.

[0027] In one embodiment, the particle size of the perovskite oxide is 20 to 150 nm.

[0028] The perovskite oxide is prepared by one of electrochemical deposition, chemical vapor deposition, sol-gel method and hydrothermal method.

[0029] This particle size can ensure the stability of the overall coolant composition and is not prone to precipitation.

[0030] In a second aspect, the present invention provides a method for preparing a coolant for a fuel cell, comprising the following steps: at 20-50° C., first, stirring and mixing deionized water, amino acid salt, acrylate, dioctyl azelate, tributyl phosphate and a metal inhibitor for 0.5-1 h at a speed of 300-600 r / min, then adding a buffer and stirring at 500-600 r / min for 0.5-1 h; then, slowly adding the thermal conductive additive at 500-700 r / min, then reducing the stirring speed to 300-600 r / min, and continuing to mix for 2-8 h to obtain the coolant for the fuel cell.

[0031] The coolant can be prepared by a simple mixing method, which greatly reduces the difficulty of preparation and the difficulty of operation for operators.

[0032] The beneficial effects of the present invention are: A coolant for a fuel cell proposed in the present invention has achieved significant technological progress by optimizing the formula and introducing specific thermal conductive additives. Specifically, the coolant can significantly improve the heat transfer efficiency and effectively improve the thermal management performance of the fuel cell. In addition, it has excellent antifreeze ability, ensuring that the fuel cell can still work normally under extremely low temperature conditions. In addition, the coolant of the present invention has a long service life, and it can continuously protect the fuel cell cooling system from the negative effects of increased conductivity during long-term use. At the same time, the coolant also shows high compatibility with organic polymers and long-term corrosion protection for various metal materials such as aluminum, copper, and stainless steel, ensuring the stable operation of the fuel cell system. Finally, the coolant of the present invention is highly compatible with proton exchange membranes, does not cause proton membrane poisoning, and further ensures the overall performance and safety of the fuel cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 This is a graph showing the change in battery conductivity of the coolant prepared in Examples 1 to 3 and the comparative example as a function of the number of days of power-on in Test Example 1 of the present invention; Figure 2 This is a graph showing the change in battery temperature with the number of power-on days using the coolants prepared in Examples 1 to 3 and the comparative example in Experimental Example 2 of the present invention. DETAILED DESCRIPTION

[0034] The present invention will be further described below in conjunction with the accompanying drawings. Example

[0035] This embodiment provides a fuel cell coolant and a preparation method thereof: The raw materials are as follows: 55.5 kg of deionized water, 35 kg of amino acid salt, 5 kg of dioctyl azelaic acid, 0.1 kg of sodium tripolyphosphate, 0.2 kg of tributyl phosphate, 0.8 kg of acrylate, 1.2 kg of ethylenediaminetetraacetic acid, and 2.5 kg of thermal conductive additives (the outer layer is alumina, and the inner layer is graphene and calcium titanium oxide).

[0036] The method is as follows: under room temperature, deionized water, amino acid salt, acrylate, dioctyl azelaic acid, tributyl phosphate and ethylenediaminetetraacetic acid are first mixed by stirring for 0.5 h at a speed of 300 r / min; then sodium tripolyphosphate is added and stirred for 0.5 h at a speed of 300 r / min; under stirring at 500 r / min, a thermal conductive additive is slowly added (the preparation of the thermal conductive additive includes the following steps: acetic acid, acetylacetone and aluminum nitrate are mixed evenly in a mass ratio of 1:7:2, and ammonia water with a mass fraction of 10% is added dropwise to a pH of 6.5 to form an aluminum hydroxide colloidal solution. At room temperature, under stirring mode (300 r / min), graphene and lanthanum nickelate with a particle size of 20 nm are added to the aluminum hydroxide colloidal solution. The mass ratio of the aluminum hydroxide colloidal solution and the mixture of graphene and lanthanum nickelate is 20:1. Stir for 1 h, filter at room temperature, and collect the solid. Dry at 120°C for 3 h, and heat the dried solid at 1000°C for 2 h under nitrogen protection. h of high temperature sintering to obtain the thermal conductive additive), then reducing the stirring speed to 300 r / min and continuing mixing for 2 h; thus, the fuel cell coolant was obtained. Example 2: This embodiment provides a fuel cell coolant and a preparation method thereof: The raw materials are as follows: 40 kg of deionized water, 50 kg of amino acid salt, 3 kg of dioctyl azelate, 0.2 kg of disodium hydrogen phosphate, 0.4 kg of tributyl phosphate, 1.1 kg of acrylate, 3.6 kg of hydroxyethyl diphosphonate, and 1.7 kg of thermal conductive additive (the outer layer is copper oxide, and the inner layer is reduced graphene and cobalt lanthanum nickelate).

[0037] The method is as follows: at 50°C, deionized water, amino acid salt, acrylate, dioctyl azelate, tributyl phosphate and hydroxyethylidene diphosphonate are first mixed by stirring for 1 h at a speed of 600 r / min; then disodium hydrogen phosphate is added and stirred for 1 h at a speed of 600 r / min; under the stirring condition of 700 r / min, a thermal conductive additive is slowly added (the preparation of the thermal conductive additive includes the following steps: acetic acid, acetylacetone and copper nitrate are mixed evenly in a mass ratio of 1:7:2, and ammonia water with a mass fraction of 10% is added dropwise to a pH of 6.5 to form a copper hydroxide colloidal solution. At room temperature, under stirring mode (300 r / min), graphene and lanthanum cobalt nickelate (LaNi0.5Co1O3) with a particle size of 150 nm are added to the copper hydroxide colloidal solution. The mass ratio of the copper hydroxide colloidal solution and the mixture of reduced graphene and lanthanum cobalt nickelate is 20:1. Stir for 1 h, filter at room temperature, and collect the solid. 120°C, dry for 3 h, sintering the dried solid at 1000°C for 2 h under nitrogen protection to obtain the thermal conductive additive), then reducing the stirring speed to 600 r / min and continuing mixing for 8 h; thus, the fuel cell coolant was obtained. Example

[0038] This embodiment provides a fuel cell coolant and a preparation method thereof: The raw materials are as follows: 47.5 kg of deionized water, 42 kg of amino acid salt, 2.5 kg of dioctyl azelaic acid, 0.1 kg of a mixture of sodium phosphate and disodium hydrogen phosphate, 0.3 kg of tributyl phosphate, 0.9 kg of acrylate, 2.4 kg of a mixture of benzotriazole, benzothiophene and benzothiopyridine, and 3.3 kg of a thermal conductive additive (the outer layer is copper oxide, and the inner layer is graphene-lanthanum strontium cobalt iron).

[0039] The method is as follows: at 35°C, deionized water, amino acid salt, acrylate, dioctyl azelate, tributyl phosphate, benzotriazole, benzothiophene, and benzothiopyridine are first mixed by stirring for 0.8 h at a speed of 450 r / min; then disodium hydrogen phosphate and sodium phosphate are added, and stirred for 0.8 h at a speed of 450 r / min; under the stirring condition of 600 r / min, a thermal conductive additive is slowly added (the preparation of the thermal conductive additive includes the following steps: acetic acid, acetylacetone, and copper nitrate are mixed evenly in a mass ratio of 1:7:2, and ammonia water with a mass fraction of 10% is added dropwise to a pH of 6.5 to form a copper hydroxide colloidal solution. At room temperature, graphene-particle size 80 is added to the copper hydroxide colloidal solution under stirring mode (300 r / min). The mass ratio of the mixture of lanthanum strontium cobalt iron (La0.6Sr0.4Co0.5Fe0.5O3) with a diameter of 1 nm, copper hydroxide colloidal solution and reduced graphene-lanthanum strontium cobalt iron is 20:1, stirred for 1 hour, filtered at room temperature, and the solid was collected. 120℃, dried for 3 hours, and the dried solid was sintered at 1000℃ for 2 hours under nitrogen protection to obtain the thermal conductive additive), then the stirring speed was reduced to 450 r / min, and the mixing was continued for 5 hours; the fuel cell coolant was obtained. Comparative Example raw material: Deionized water 46 kg, ethylene glycol 35 kg, sodium nitrite 0.5 kg, benzotriazole 0.3 kg, sodium tripolyphosphate 0.2 kg, sodium silicate 0.1 kg, polydimethylsiloxane 0.1 kg, disodium hydrogen phosphate 0.2 kg, isothiazolinone 0.1 kg; method: Prepare the container: Choose a clean stirring kettle and make sure it is free of any impurities.

[0040] Add deionized water: Add deionized water into the stirring kettle and turn on the stirrer.

[0041] Add ethylene glycol: Slowly add ethylene glycol while stirring and continue stirring for 30 minutes to ensure a uniform mix.

[0042] Add corrosion inhibitor: add sodium nitrite and benzotriazole in sequence, and continue stirring for 30 minutes after each addition.

[0043] Add ion inhibitors: add sodium tripolyphosphate and sodium silicate in sequence, and continue stirring for 30 minutes after each addition.

[0044] Add defoamer: Add polydimethylsiloxane and continue stirring for 30 minutes.

[0045] Add pH adjuster: Add disodium hydrogen phosphate and continue stirring for 30 minutes to adjust the pH to the desired range.

[0046] Add the antimicrobial agent: Add the isothiazolinone last and continue stirring for 30 minutes to ensure a uniform mix.

[0047] Filtration: The mixed coolant is filtered through a filter to remove possible impurities, and the preparation is complete.

[0048] Test Example 1 300 mL of the coolant prepared in the above Examples 1-3 and the comparative example was respectively passed into a 300-310W stack for conductivity testing (hydrogen 0.1 MPa, air 0.1 MPa, flow rate of 700 mL / min, 2800 mL / min, 60% humidification, 50-60°C), and the battery conductivity of the stack was continuously recorded at the same time every day. The results are as follows: Figure 1 As shown, according to Figure 1 The results show that the fuel cell coolant prepared in Examples 1 to 3 has a lower conductivity than the coolant system prepared in the comparative example, thus having better quality and more in line with the requirements of the industry. (The industry requires that the coolant conductivity should not exceed 5 μs / cm) Test Example 2 300 mL of the coolant prepared in Examples 1 to 3 and the comparative example was respectively passed into a 300-310W stack for temperature testing (hydrogen 0.1 MPa, air 0.1 MPa, flow rate 700 mL / min, 2800 mL / min, 60% humidification), and the battery temperature of the stack was continuously recorded at the same time every day. The results are as follows: Figure 2 As shown, according to Figure 2 The results show that the coolants prepared in Examples 1 to 3 are significantly better than the coolants prepared in the comparative examples in terms of battery cooling efficiency.

[0049] In the description of the present invention, it is necessary to understand that the terms "upper", "lower", "bottom", "top", "front", "back", "inside", "outside", "left", "right", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0050] Although the present invention is described herein with reference to specific embodiments, it should be understood that these embodiments are merely examples of the principles and applications of the present invention. It should therefore be understood that many modifications may be made to the exemplary embodiments and that other arrangements may be devised without departing from the spirit and scope of the present invention as defined by the appended claims. It should be understood that the various dependent claims and features described herein may be combined in a manner different from that described in the original claims. It should also be understood that features described in conjunction with individual embodiments may be used in other described embodiments.

Claims

1. A coolant for a fuel cell, characterized in that: Including the following raw materials: Deionized water 40~55.5 wt%, amino acid salt 35~50 wt%, dioctyl azelate 0.5~5 wt%, buffer 0.1~0.2wt%, tributyl phosphate 0.2~0.4 wt%, acrylate 0.8~1.1 wt%, non-ionic metal inhibitor 1.2~3.6 wt%, thermal conductive additive 1.6~4.8 wt%.

2. The fuel cell coolant according to claim 1, characterized in that: The buffer comprises at least one of sodium tripolyphosphate, disodium hydrogen phosphate and sodium phosphate.

3. The fuel cell coolant according to claim 1, characterized in that: The nonionic metal inhibitor includes at least one of ethylenediaminetetraacetic acid, hydroxyethylenediphosphonate, benzotriazole, benzothiophene, and benzothiopyridine.

4. The fuel cell coolant according to claim 1, characterized in that: The thermal conductive additive comprises an outer layer and an inner layer, wherein the outer layer completely covers the inner layer, the outer layer is Al2O3 or CuO, and the inner layer comprises perovskite oxide and at least one of reduced graphene, graphite, and a perovskite oxide-graphene composite.

5. The fuel cell coolant according to claim 4, characterized in that: The inner layer and the outer layer constitute a sphere and / or a tube bundle structure of a core-shell structure.

6. The fuel cell coolant according to claim 4, characterized in that: The perovskite oxide includes at least one of lanthanum nickelate, lanthanum cobalt nickelate, and lanthanum strontium cobalt iron.

7. The fuel cell coolant according to claim 6, characterized in that: The chemical formula of the lanthanum cobalt nickelate is LaNi x Co y O3, wherein 0≤x≤0.5, 0≤y≤1; the chemical formula of the lanthanum strontium cobalt iron is La 0.6 Sr 0.4 Co (1-y2) Fe y2 O3, where 0≤y2≤1.

8. The fuel cell coolant according to claim 4, characterized in that: The particle size of the perovskite oxide is 20 to 150 nm.

9. A method for preparing a fuel cell coolant according to any one of claims 1 to 8, characterized in that: The method comprises the following steps: firstly, at 20-50° C., mixing deionized water, amino acid salt, acrylate, dioctyl azelate, tributyl phosphate and metal inhibitor for 0.5-1 h at a speed of 300-600 r / min, and then adding a buffer and stirring at 500-600 r / min for 0.5-1 h; Then, the thermal conductive additive is slowly added at 500-700 r / min, and then the stirring speed is reduced to 300-600 r / min, and the mixing is continued for 2-8 hours to obtain the fuel cell coolant.

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