Fuel cell cooling liquid and preparation method thereof

Abstract

The invention relates to the technical field of fine chemical engineering, and discloses a fuel cell cooling liquid and a preparation method thereof, and the preparation method comprises the following steps: preparation of a basic liquid, construction of a corrosion inhibition system, ion inhibition treatment, addition of a functional auxiliary agent and post-treatment. According to the composite corrosion inhibitor, zinc ions are anchored to gap sites of a silicate framework through the surface loading effect of sodium silicate and nano-zinc oxide under the shear dispersion condition, a compact composite passivation film is formed on the surface of a metal pipeline, and an electrode potential active area is covered; meanwhile, molybdate ions are subjected to a self-repairing reaction at the defect position of a passivation film preferentially by virtue of the oxidation-reduction characteristic of the molybdate ions, and formation of a galvanic corrosion microbattery is blocked by dynamically filling microcracks, so that the integrity of a corrosion inhibition system is improved; all the components of the composite corrosion inhibitor generate a synergistic effect in a specific proportion, so that the cooling liquid can maintain stable corrosion resistance for a long time.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of fine chemical technology, in particular to a fuel cell coolant and a preparation method thereof. BACKGROUND

[0002] Fuel cell is a kind of chemical device that converts chemical energy of fuel into electric energy, also known as electrochemical generator, which is the fourth generation of power generation technology after hydraulic power generation, thermal power generation and atomic power generation. Its advantages are pollution-free emission, low noise and high energy conversion efficiency, and it is considered as the preferred high-efficiency and clean power generation technology in the 21st century, and also an ideal mobile power technology, which can be widely used in many fields such as automobile transportation, military backup power supply, underwater submarine and so on.

[0003] At present, in the preparation and application process of fuel cell coolant, due to the low-temperature crystallization tendency of the base coolant component, when the low-temperature working condition test is carried out, the solidification phase change material may block the flow state of the coolant in the microchannel, and the influence degree of the phase change material on the heat transfer efficiency cannot be monitored in real time. When the local crystallization phenomenon is not eliminated in time, the temperature difference inside the fuel cell stack will exceed the safety threshold, which will affect the temperature control accuracy. At the same time, when verifying the corrosion inhibition performance of the coolant, there is no in-situ monitoring means for the dynamic change of the electrochemical microenvironment, which cannot identify whether the non-steady-state galvanic corrosion is formed on the surface of the metal pipeline, which will cause the local rupture of the protective film of the corrosion inhibitor in actual service, and it is difficult to realize the adaptive adjustment of the corrosion inhibitor concentration when abnormal corrosion occurs. When evaluating the ion conductivity characteristics of the coolant, due to the difference in mobility of ions with different valence, when the high potential gradient simulation test is carried out, the contribution rate of different ions to conduction cannot be accurately separated, which leads to systematic deviation in the evaluation of the real conductivity of the coolant, misleads the boundary parameter setting of the insulation safety design, and reduces the reliability and durability of the fuel cell system operation.

[0004] Therefore, the present application provides a fuel cell coolant and a preparation method thereof to solve the above problems. SUMMARY

[0005] (I) Technical problems solved In view of the deficiencies of the prior art, the present application provides a fuel cell coolant and a preparation method thereof, which solves the problems raised in the background art.

[0006] (II) Technical solutions

[0007] In order to achieve the above purpose, the present application provides the following technical solutions: a fuel cell coolant and a preparation method thereof, comprising the following steps: Step one, preparation of base liquid, add propylene glycol and ethylene glycol into the reaction kettle according to the proportion, heat to 50-70 DEG C, and stir at 200-400 r / min; Step two, corrosion inhibitor system construction, add composite corrosion inhibitor to the reaction kettle, maintain temperature and increase the speed to 500-800 r / min, continue stirring for 30-60 minutes; Step three, ion suppression treatment, add ion conductive inhibitor in batches, control the interval of each batch addition for 10 minutes, after adding, disperse for 15-45 minutes under ultrasonic assistance at a frequency of 20-40 kHz; Step four, functional additive addition, add antioxidant and defoaming agent in turn, cool to 30-45℃, then mature for 1-2 hours at 100-300 r / min; Step five, post-treatment, filter and degas to obtain the finished product coolant.

[0008] Preferably, the ion conductive inhibitor in step three is added in the following way: Dissolve boric acid in hot water at 50-60℃ to prepare a 30wt% solution, then pre-mix the surface modified ceramic microspheres with the solution in proportion and immerse for 10 minutes; Add the mixture in 3-5 batches, each batch has the same amount, and the reaction kettle temperature is controlled at 50-60℃ during addition.

[0009] Preferably, the composite corrosion inhibitor in step two is added by negative pressure suction: Maintain the vacuum degree of the reaction kettle at 0.05-0.08 MPa, add uniformly at a rate of 1-3 kg / min through a screw feeder, and open the high-speed dispersion disc during the whole feeding process, with a linear speed of the dispersion disc not less than 15 m / s.

[0010] Preferably, the antioxidant is a compound of methyl benzotriazole and inositol hexaphosphate, with a mass ratio of 1:0.2-1:0.5, which needs the following pretreatment before being added in step four: Dissolve the two components in propylene glycol at 60-80℃ to prepare a 10-20wt% mother liquor, and ultrasonically shake for 20 minutes to fully complex.

[0011] Preferably, the defoaming agent is a polyether modified silicone emulsion, which needs to meet the following conditions when added: After the reaction kettle is cooled to below 40℃, dilute the defoaming agent with 5 times the amount of propylene glycol, slowly drop it at a rate of 0.5-2 mL / min through a micro-injection pump, maintain gentle stirring at 200-300 r / min during the dropping process, and the reaction kettle temperature should be ≤40℃ during dropping to avoid decomposition of the organic silicon caused by high temperature.

[0012] Preferably, the filtration in step five uses a two-stage filtration system: First, coarsely filter through a 50-100 μm stainless steel filter screen, then fine filter through a 0.1-0.5 μm polytetrafluoroethylene membrane; The degassing treatment is carried out at a vacuum degree of 0.095-0.098 MPa and a temperature of 30-40 DEG C for 30-90 minutes.

[0013] Preferably, the cooling liquid is composed of the following raw materials by weight: The base coolant: 70-85 parts; The composite corrosion inhibitor: 8-15 parts; The ion conductive inhibitor: 5-12 parts; The antioxidant: 0.5-3 parts; The defoaming agent: 0.1-1 part; The base coolant is a mixture of propylene glycol and ethylene glycol with a mass ratio of 2:1-1:2; The composite corrosion inhibitor is compounded by sodium silicate, sodium molybdate and nano zinc oxide with a mass ratio of 3:1:0.5-5:2:1; The ion conductive inhibitor is a combination of surface-modified ceramic microspheres and boric acid with a mass ratio of 4:1-6:1.

[0014] Preferably, the ceramic microspheres in the ion conductive inhibitor are prepared by the following method: Alumina ceramic balls with a particle size of 20-50 microns are selected and placed in a plasma treatment chamber, vacuumed to 0.001-0.05 Pa, argon gas is introduced to maintain the gas pressure at 10-30 Pa, and treated at a power of 200-500 W for 10-30 minutes; The treated ceramic balls are immersed in an ethanol solution containing a silane coupling agent, oscillated at a constant temperature of 40-60 DEG C for 1-3 hours, and then dried at 80-100 DEG C after being taken out to obtain surface-modified ceramic microspheres.

[0015] Preferably, the silane coupling agent uses at least one of gamma-aminopropyl triethoxysilane or gamma-glycidyl ether propyl trimethoxysilane, and the ethanol solution concentration is 1-5 wt%, and the mass-volume ratio of ceramic balls to solution is 1g:10mL.

[0016] Preferably, the composite corrosion inhibitor is premixed by the following steps: Sodium silicate, sodium molybdate and nano zinc oxide are added to a high shear disperser, the temperature is controlled at 30-40 DEG C, and the stirring speed is controlled at 1000-3000 r / min for 20-50 minutes to uniformly load the nano zinc oxide on the surface of the silicate particles. (Three) beneficial effects

[0017] Compared with the prior art, the present application provides a fuel cell cooling liquid and a preparation method thereof, which has the following beneficial effects: 1. In the present application, the composite corrosion inhibitor is formed by the surface loading effect of sodium silicate and nano zinc oxide under shearing dispersion conditions, so that zinc ions are anchored in the gap sites of the silicate skeleton, a dense composite passivation film is formed on the surface of the metal pipeline, and the electrode potential active area is covered; at the same time, the molybdate ion has the characteristics of redox, and preferentially occurs self-repairing reaction at the defect of the passivation film, and through dynamic filling of micro-cracks, the formation of galvanic corrosion micro-battery is blocked, and the integrity of the corrosion inhibitor system is improved; the synergistic effect of each component of the composite corrosion inhibitor in a specific ratio makes the cooling liquid maintain stable corrosion resistance for a long time.

[0018] 2. In the present application, the ion conductive inhibitor is formed by the synergistic mechanism of surface modified ceramic microspheres and boric acid, the silicon hydroxyl group on the surface of the plasma activated ceramic microspheres forms a boron-silicon coordination bond with the boric acid molecules, and a stable three-dimensional barrier network is constructed in the cooling liquid; the network structure selectively adsorbs high-valence metal ions due to its surface negative charge characteristics, and the steric hindrance effect of the modified group inhibits the migration rate of anions; by controlling the ratio of ceramic microspheres and boric acid, the gradient regulation of the cooling liquid conductive channel is realized, and the electrical insulation characteristics are optimized.

[0019] 3. In the present application, the preparation process realizes the layer-by-layer dispersion of the ion inhibitor under the condition of ultrasonic assistance by controlling the functional component addition strategy in stages, ensures that the ceramic microspheres are uniformly distributed in the base liquid in the form of single particles; the corrosion inhibitor uses vacuum negative pressure feeding combined with high-speed shearing to force the nanoparticles to overcome van der Waals force and achieve molecular-level dispersion; the complex formed by the pretreatment of the antioxidant realizes the slow-release function through the propylene glycol carrier, and neutralizes the free radical chain reaction; the matching of temperature-stirring-time parameters in the whole process makes each component reach a metastable state balance, and finally forms a stable colloidal system with a long service life. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 The flow chart of the fuel cell cooling liquid and the preparation method thereof according to the present application. DETAILED DESCRIPTION

[0021] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0022] Embodiment 1, a fuel cell cooling liquid and a preparation method thereof, comprising the following steps: Step one, base liquid preparation, add propylene glycol and ethylene glycol to the reaction kettle according to the proportion, heat to 50℃, and stir at 200r / min; Step 2: Construction of corrosion inhibition system: Add composite corrosion inhibitor to the reactor, maintain the temperature and increase the speed to 500 r / min, and continue stirring for 30 minutes; Step 3: Ion suppression treatment: add ion conductivity inhibitor in batches, with an interval of 10 minutes between each addition. After addition, disperse the inhibitor at a frequency of 20 kHz for 15 minutes under the assistance of ultrasound. Step 4: Add functional additives, add antioxidant and defoamer in sequence, cool to 30°C and mature at 100 rpm for 1 hour; Step 5: Post-processing: filtering and degassing to obtain the finished coolant.

[0023] The ion conductivity inhibitor is added in step 3 as follows: First, dissolve boric acid in 50°C hot water to prepare a 30wt% solution, then pre-mix the surface-modified ceramic microspheres with the solution in proportion and soak for 10 minutes; The mixed material was added in three batches, with the amount added in each batch being equal, and the temperature of the reactor was controlled at 50°C during the addition.

[0024] In step 2, the composite corrosion inhibitor is added by negative pressure suction: Maintain the vacuum degree of the reactor at 0.05 MPa, add the material evenly at a rate of 1 kg / min through a spiral feeder, and turn on the high-speed dispersing disk during the entire feeding process, with a linear speed of not less than 15 m / s.

[0025] The antioxidant is a mixture of methylbenzotriazole and phytate, with a mass ratio of 1:0.2. Before adding in step 4, it needs to be pretreated as follows: The two components were dissolved in propylene glycol at 60°C to prepare a 10 wt% mother liquor, and ultrasonically shaken for 20 minutes to fully complex them.

[0026] The defoamer is a polyether-modified silicone emulsion, and its addition must meet the following conditions: After the reactor is cooled to below 40°C, the defoaming agent is diluted with 5 times the amount of propylene glycol and slowly added dropwise at a rate of 0.5 mL / min using a microinjection pump. Gentle stirring is maintained at 200 r / min during the addition process. The reactor temperature is ≤40°C during the addition to avoid decomposition of the silicone caused by high temperature.

[0027] The filtration in step five uses a two-stage filtration system: First, it was coarsely filtered through a 50 μm stainless steel filter, and then finely filtered through a 0.1 μm polytetrafluoroethylene membrane; The degassing treatment was continued for 30 minutes at a vacuum degree of 0.095 MPa and a temperature of 30°C.

[0028] The coolant is composed of the following raw materials in parts by weight: Basic coolant: 70 parts; Composite corrosion inhibitor: 8 parts; Ion conduction inhibitor: 5 parts; Antioxidant: 0.5 parts; Defoaming agent: 0.1 parts; The base coolant is a mixture of propylene glycol and ethylene glycol with a mass ratio of 2:1; The composite corrosion inhibitor is compounded by sodium silicate, sodium molybdate and nano zinc oxide with a mass ratio of 3:1:0.5; The ion conduction inhibitor is a combination of surface-modified ceramic microspheres and boric acid with a mass ratio of 4:1.

[0029] The ceramic microspheres in the ion conduction inhibitor are prepared by the following method: Alumina ceramic balls with a particle size of 20 μm are selected and placed in a plasma treatment chamber. Vacuum is drawn to 0.05 Pa, argon gas is introduced to maintain a gas pressure of 10 Pa, and treatment is carried out at a power of 200 W for 10 minutes. The treated ceramic balls are immersed in an ethanol solution containing silane coupling agent, oscillated at 40°C for 1 hour, and then taken out and dried at 80°C to obtain surface-modified ceramic microspheres.

[0030] The silane coupling agent is at least one of γ-aminopropyl triethoxysilane or γ-glycidyl ether propyl trimethoxysilane, and its ethanol solution concentration is 1 wt%, and the mass-volume ratio of ceramic balls to solution is 1 g:10 mL.

[0031] The composite corrosion inhibitor is premixed by the following steps: Sodium silicate, sodium molybdate and nano zinc oxide are added to a high shear disperser, the temperature is controlled at 30°C, and the stirring speed is 1000 r / min for 20 minutes to make the nano zinc oxide uniformly loaded on the surface of the silicate particles.

[0032] Example 2, a fuel cell coolant and its preparation method, comprising the following steps: Step one, base liquid preparation, propylene glycol and ethylene glycol are added to the reaction kettle in proportion, heated to 60°C, and stirred at 300 r / min; Step two, corrosion inhibitor system construction, composite corrosion inhibitor is added to the reaction kettle, the temperature is maintained and the stirring speed is increased to 600 r / min, and the stirring is continued for 45 minutes; Step three, ion inhibition treatment, ion conduction inhibitor is added in batches, the interval between each batch is controlled for 10 minutes, and after the addition is completed, it is dispersed for 30 minutes under the assistance of ultrasonic wave with a frequency of 30 kHz; Step four, functional additive addition, antioxidant and defoaming agent are added in turn, and after cooling to 40°C, it is aged for 1.5 hours at 200 r / min; Step five, post-treatment, the finished coolant is obtained after filtration and degassing.

[0033] The ion conductive inhibitor in step three is added in the following way: Dissolve boric acid in hot water at 55°C to form a 30wt% solution, then pre-mix the surface-modified ceramic microspheres with the solution in proportion and immerse for 10 minutes; Add the mixture in 4 batches, with equal amount in each batch, and control the temperature of the reaction kettle at 55°C during addition.

[0034] The composite corrosion inhibitor in step two is added by negative pressure suction: Maintain the vacuum degree of the reaction kettle at 0.06MPa, and add uniformly at a rate of 2kg / min through the screw feeder, with the high-speed dispersing disc turned on during the whole process, and the linear speed of the dispersing disc not less than 15m / s.

[0035] The antioxidant is a compound of methyl benzotriazole and inositol hexaphosphate, with a mass ratio of 1:0.3, which needs the following pretreatment before being added in step four: Dissolve the two components in propylene glycol at 70°C to form a 15wt% mother liquor, and ultrasonically shake for 20 minutes to fully complex.

[0036] The defoaming agent is a polyether-modified silicone emulsion, which needs to meet the following conditions for addition: After the reaction kettle is cooled to below 40°C, dilute the defoaming agent with 5 times the amount of propylene glycol, and slowly drop it at a rate of 1.5mL / min through a micro-injection pump, maintaining gentle stirring at 250r / min during the dropping process. The temperature of the reaction kettle should be ≤40°C during dropping to avoid decomposition of the silicone caused by high temperature.

[0037] The filtration in step five uses a two-stage filtration system: First, coarsely filter through a 70μm stainless steel filter screen, and then finely filter through a 0.3μm polytetrafluoroethylene membrane; The degassing treatment is carried out at a vacuum degree of 0.096MPa and a temperature of 35°C for 60 minutes.

[0038] The cooling liquid is composed of the following ingredients by weight: Basic coolant: 75 parts; Composite corrosion inhibitor: 12 parts; Ion conductive inhibitor: 10 parts; Antioxidant: 2 parts; Defoaming agent: 0.5 parts; The basic coolant is a mixture of propylene glycol and ethylene glycol, with a mass ratio of 1:1; The composite corrosion inhibitor is a compound of sodium silicate, sodium molybdate and nano zinc oxide, with a mass ratio of 4:1:0.8; The ion conductive inhibitor is a combination of surface-modified ceramic microspheres and boric acid, with a mass ratio of 5:1.

[0039] The ceramic microspheres in the ion conduction inhibitor are prepared by the following method: Alumina ceramic balls with a particle size of 30 μm are selected and placed in a plasma treatment chamber, vacuumed to 0.025 Pa, argon gas is introduced to maintain the gas pressure at 20 Pa, and treated at a power of 350 W for 20 minutes; The treated ceramic balls are immersed in an ethanol solution containing a silane coupling agent, oscillated at 50°C for 2 hours, and then taken out and dried at 90°C to obtain surface-modified ceramic microspheres.

[0040] The silane coupling agent is at least one of γ-aminopropyl triethoxysilane or γ-glycidyl ether propyl trimethoxysilane, and the concentration of the ethanol solution is 3wt%, and the mass-volume ratio of the ceramic balls to the solution is 1g:10mL.

[0041] The composite corrosion inhibitor is premixed according to the following steps: Sodium silicate, sodium molybdate and nano zinc oxide are added to a high-shear dispersing machine, the temperature is controlled at 35°C, and the stirring speed is 2000r / min for 35 minutes to uniformly load the nano zinc oxide on the surface of the silicate particles.

[0042] Example 3, a fuel cell coolant and a preparation method thereof, comprising the following steps: Step one, preparation of the base liquid, add propylene glycol and ethylene glycol to the reaction kettle in proportion, heat to 70°C, and stir at 400r / min; Step two, construction of the corrosion inhibition system, add the composite corrosion inhibitor to the reaction kettle, maintain the temperature and increase the stirring speed to 800r / min, and continue stirring for 60 minutes; Step three, ion inhibition treatment, add the ion conduction inhibitor in batches, control the interval between each batch addition to be 10 minutes, and after the addition is completed, disperse under the assistance of ultrasonic waves at a frequency of 40kHz for 45 minutes; Step four, addition of functional additives, add the antioxidant and the defoaming agent in turn, cool to 45°C, and mature at 300r / min for 2 hours; Step five, post-treatment, filter and degas to obtain the finished coolant.

[0043] The addition method of the ion conduction inhibitor in step three is: Dissolve boric acid in hot water at 60°C to prepare a 30wt% solution, and then pre-mix the surface-modified ceramic microspheres with the solution in proportion and soak for 10 minutes; The mixture is added in 5 batches, each batch has the same amount, and the temperature of the reaction kettle is controlled at 60°C during addition.

[0044] The addition of the composite corrosion inhibitor in step two is carried out by negative pressure suction: The vacuum degree of the reaction kettle is maintained at 0.08 MPa, and the uniform addition is carried out at a rate of 3 kg / min through the screw feeder, and the high-speed dispersing disc is opened during the whole feeding process, and the linear speed of the dispersing disc is not less than 15 m / s.

[0045] The antioxidant is a compound of methyl benzotriazole and myo-inositol hexaphosphate, and the mass ratio of the two is 1:0.5. Before adding in step four, the following pretreatment is required: The two components are dissolved in 80℃ propylene glycol to prepare a 20wt% mother liquor, and ultrasonic oscillation is performed for 20 minutes to fully complex.

[0046] The defoaming agent is a polyether modified silicone emulsion, and the following conditions need to be met when adding it: After the reaction kettle is cooled to below 40℃, the defoaming agent is diluted with 5 times the amount of propylene glycol, and slowly added at a rate of 2mL / min through a micro-injection pump. During the addition process, gentle stirring at 300r / min is maintained, and the temperature of the reaction kettle during the addition process is ≤40℃ to avoid high temperature decomposition of silicone.

[0047] The filtration of step five adopts a two-stage filtration system: First, it is coarsely filtered through a 100μm stainless steel filter, and then it is finely filtered through a 0.5μm polytetrafluoroethylene membrane; The degassing treatment is carried out at a vacuum degree of 0.098 MPa and a temperature of 40℃ for 90 minutes.

[0048] The cooling liquid is composed of the following weight parts of raw materials: Basic coolant: 85 parts; Composite corrosion inhibitor: 15 parts; Ion conductivity inhibitor: 12 parts; Antioxidant: 3 parts; Defoaming agent: 1 part; The basic coolant is a mixture of propylene glycol and ethylene glycol with a mass ratio of 1:2; The composite corrosion inhibitor is compounded by sodium silicate, sodium molybdate and nano zinc oxide with a mass ratio of 5:2:1; The ion conductivity inhibitor is a combination of surface modified ceramic microspheres and boric acid with a mass ratio of 6:1.

[0049] The ceramic microspheres in the ion conductivity inhibitor are prepared by the following method: Select alumina ceramic balls with a particle size of 50μm, place them in a plasma treatment chamber, vacuum to 0.001 Pa, introduce argon to maintain a gas pressure of 30 Pa, and treat at a power of 500W for 30 minutes; Soak the treated ceramic balls in an ethanol solution containing silane coupling agent, oscillate at 60℃ for 3 hours, take out and dry at 100℃ to obtain surface modified ceramic microspheres.

[0050] The silane coupling agent is at least one of γ-aminopropyl triethoxysilane or γ-glycidoxypropyl trimethoxysilane, and the concentration of the ethanol solution is 5wt%, and the mass-volume ratio of the ceramic ball to the solution is 1g:10mL.

[0051] The composite corrosion inhibitor is premixed according to the following steps: The sodium silicate, sodium molybdate and nano zinc oxide are added to a high-shear dispersing machine, the temperature is controlled at 40℃, and the stirring speed is 3000r / min for 50 minutes, so that the nano zinc oxide is uniformly loaded on the surface of the silicate particles.

[0052] Comparative Example 1, which is different from Example 1 in that the composite corrosion inhibitor is not added when preparing the cooling liquid, and the corrosion inhibitor system construction process is directly skipped; Comparative Example 2, which is different from Example 1 in that the ion conductive inhibitor is not added when preparing the cooling liquid, and the ion inhibition treatment process is cancelled; Comparative Example 3, which is different from Example 1 in that the batch addition and ultrasonic dispersion treatment are not implemented, and the ion conductive inhibitor is added at one time and the ultrasonic wave assistance is cancelled; Comparative Example 4, which is different from Example 1 in that the pretreatment is not performed before adding the antioxidant, and the propylene glycol mother liquor configuration and ultrasonic oscillation steps are cancelled.

[0053] The fuel cell cooling liquids prepared in Examples 1-3 and Comparative Examples 1-4 are subjected to performance testing, and the test items and test methods are as follows: The conductivity test is performed under the conditions of constant temperature 25℃±0.5℃ and direct current voltage 50mV, using a platinum black electrode system, measuring the impedance value at a frequency of 1kHz, and calculating the ion conductivity; The corrosion performance test is performed in a circulating system at 50℃±2℃ and a flow rate of 0.5m / s, the carbon steel, copper and aluminum alloy standard test pieces are hung, and after 200 hours of continuous operation, the test pieces are taken out, and the corrosion rate is calculated according to the weight loss method; The freezing point test is performed by taking 100mL of the sample into a low-temperature bath, cooling at a rate of 0.5℃ / min, recording the initial crystallization temperature with a photoelectric sensor, and repeating the test for 3 times to take the average value; The high-temperature stability test is performed by placing the tin-plated copper pieces in a constant-temperature oven at 135℃±2℃ for 72 hours, then taking them out, observing the color change of the cooling liquid, and measuring the content of the precipitate.

[0054] The test data of the fuel cell cooling liquids prepared in Examples 1-3 and Comparative Examples 1-4 are recorded in the following table: Test item Conductivity (pS / cm) Corrosion rate (mg / dm2.d) Freezing point (°C) Sediment content (mg / L) Example 1 3.5 x 10 -2 ]] 0.025±0.003 -42.5 15.3±0.2 Example 2 3.2 x 10 -2 ]]> 0.021±0.002 -43.2 14.8±0.3 Example 3 2.8 x 10 -2 ]] 0.018±0.002 -44.0 13.7±0.2 Comparative Example 1 28.6 x 10 -2 ]] 1.85±0.15 -35.6 62.8±1.2 Comparative Example 2 35.2 x 10 -2 ]]> 1.45±0.12 -32.3 83.5±1.5 Comparative Example 3 12.3 x 10 -2 ]]> 0.82±0.08 -38.5 35.6±0.8 Comparative Example 4 8.6 x 10 -2 ]] 0.57±0.06 -37.8 42.3±0.7 By comparing and analyzing the data in the table, it can be seen that the fuel cell coolant prepared by the processes of examples 1-3 has better comprehensive performance than the coolant prepared by comparative examples 1-4, which shows that the composite corrosion inhibitor is loaded on the surface of sodium silicate and nano zinc oxide under the condition of shear dispersion, so that the zinc ions are anchored in the gap sites of the silicate skeleton, and a dense composite passivation film is formed on the surface of the metal pipeline, covering the active area of the electrode potential; at the same time, the molybdate ions have the characteristics of redox, and preferentially occur in the self-repairing reaction at the defect of the passivation film, so as to dynamically fill the microcracks and block the formation of galvanic corrosion microcells, thereby improving the integrity of the corrosion inhibition system; the synergistic effect of the components of the composite corrosion inhibitor in a specific ratio enables the coolant to maintain stable corrosion resistance for a long time. The ion conductivity inhibitor forms boron-silicon coordination bonds on the surface of the ceramic microspheres treated by plasma activation and boric acid molecules, and constructs a stable three-dimensional barrier network in the coolant; the network structure selectively adsorbs high-valence metal ions due to its surface negative charge characteristics, and the steric hindrance effect of the modified group inhibits the migration rate of anions; by controlling the ratio of ceramic microspheres and boric acid, the gradient regulation of the conductivity channel of the coolant is realized, and the electrical insulation characteristics are optimized. The preparation process realizes the layer-by-layer dispersion of the ion inhibitor under the condition of ultrasonic assistance by controlling the functional component addition strategy in stages, so as to ensure that the ceramic microspheres are uniformly distributed in the base fluid in the form of single particles; the corrosion inhibitor is added by vacuum negative pressure feeding combined with high-speed shearing, so as to force the nanoparticles to overcome van der Waals force and realize molecular-level dispersion; the complex formed by pretreatment of the antioxidant realizes the slow-release function through the propylene glycol carrier, and neutralizes the free radical chain reaction; the matching of the temperature-stirring-time parameters in the whole process makes the components reach a metastable state balance, and finally a stable colloidal system with a long service life is formed.

[0055] By comparing and analyzing the related data in the table, it can be seen that the fuel cell coolant manufactured by the application has good performance in ion inhibition, corrosion protection and low temperature antifreeze performance, and the freezing point of the low temperature antifreeze is lower than-42.5℃, and the high temperature stability is verified by the 135℃ / 72h sediment test. Therefore, the fuel cell coolant manufacturing method provided by the application has industrialization implementation value in high-end application fields such as new energy vehicles and fixed power generation systems.

[0056] It is to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting; it is not intended to exclude myriad other embodiments of the present application that other inventors can develop based on the same general inventive concepts embodied by the described embodiments. That is, although the present application is described in terms of particular embodiments and implementations, it is to be understood that the terminology used is for the purpose of descriptive clarity and that it is intended to be limited only by the words recited in the appended claims. The scope of the present application shall be limited only by the claims.

[0057] While the embodiments of the application have been shown and described herein, it is to be understood that the application is not limited to these embodiments. Rather, numerous modifications are possible without departing from the spirit and scope of the present application as delineated by the claims and their equivalents.

Claims

1. A method for preparing a fuel cell coolant, characterized in that: The following steps are involved: Step 1: Prepare the base liquid by adding propylene glycol and ethylene glycol into a reaction kettle in proportion, heating to 50-70°C, and stirring at 200-400 r / min; Step 2: Construction of corrosion inhibition system: Add composite corrosion inhibitor to the reactor, maintain the temperature and increase the speed to 500-800 r / min, and continue stirring for 30-60 minutes; Step 3: Ion suppression treatment: add ion conductive inhibitor in batches, with an interval of 10 minutes between each batch. After addition, disperse the inhibitor at a frequency of 20-40kHz for 15-45 minutes under the assistance of ultrasound. Step 4: Add functional additives, add antioxidants and defoamers in sequence, cool to 30-45°C and mature at 100-300 r / min for 1-2 hours; Step 5: Post-processing: filtering and degassing to obtain the finished coolant.

2. The method for preparing a fuel cell coolant according to claim 1, wherein: The ion conductivity inhibitor is added in step 3 as follows: First, dissolve boric acid in 50-60℃ hot water to prepare a 30wt% solution, then pre-mix the surface-modified ceramic microspheres with the solution in proportion and soak for 10 minutes; The mixed material is added in 3-5 batches, with the addition amount of each batch being equal, and the temperature of the reactor is controlled at 50-60°C during the addition.

3. The method for preparing a fuel cell coolant according to claim 1, wherein: In step 2, the composite corrosion inhibitor is added by negative pressure suction: Maintain the vacuum degree of the reactor at 0.05-0.08 MPa, add the material evenly at a rate of 1-3 kg / min through a spiral feeder, and turn on the high-speed disperser during the entire feeding process, with a linear speed of not less than 15 m / s.

4. The method for preparing a fuel cell coolant according to claim 1, wherein: The antioxidant is a compound of methylbenzotriazole and phytate, with a mass ratio of 1:0.2-1:0.

5. It needs to be pretreated as follows before being added in step 4: The two components were dissolved in propylene glycol at 60-80°C to prepare a 10-20 wt% mother liquor, and ultrasonically vibrated for 20 minutes to fully complex them.

5. The method for preparing a fuel cell coolant according to claim 1, wherein: The defoamer is a polyether-modified silicone emulsion, and its addition must meet the following conditions: After the reactor is cooled to below 40°C, dilute the defoamer with 5 times the amount of propylene glycol and slowly add it dropwise at a rate of 0.5-2 mL / min using a microinjection pump. Maintain gentle stirring at 200-300 r / min during the addition process. The reactor temperature should be ≤40°C during the addition to avoid decomposition of the silicone due to high temperature.

6. The method for preparing a fuel cell coolant according to claim 1, wherein: The filtration in step five uses a two-stage filtration system: First, coarse filter through 50-100 μm stainless steel filter, and then fine filter through 0.1-0.5 μm polytetrafluoroethylene membrane; The degassing treatment lasts for 30-90 minutes under the conditions of vacuum degree 0.095-0.098 MPa and temperature 30-40°C.

7. A fuel cell coolant prepared by the method for preparing a fuel cell coolant according to any one of claims 1 to 6, characterized in that: The coolant is composed of the following raw materials in parts by weight: Basic coolant: 70-85 parts; Composite corrosion inhibitor: 8-15 parts; Ionic conductivity inhibitor: 5-12 parts; Antioxidant: 0.5-3 parts; Defoaming agent: 0.1-1 part; The base coolant is a mixture of propylene glycol and ethylene glycol in a mass ratio of 2:1-1:2; The composite corrosion inhibitor is prepared by mixing sodium silicate, sodium molybdate and nano zinc oxide in a mass ratio of 3:1:0.5-5:2:1; The ion conduction inhibitor is a composition of surface-modified ceramic microspheres and boric acid, with a mass ratio of the two being 4:1-6:

1.

8. A fuel cell coolant according to claim 7, characterized in that: The ceramic microspheres in the ion conductive inhibitor are prepared by the following method: Alumina ceramic balls with a particle size of 20-50 μm were selected and placed in a plasma treatment chamber. The chamber was evacuated to 0.001-0.05 Pa, and argon gas was introduced to maintain the pressure at 10-30 Pa. The treatment was carried out at a power of 200-500 W for 10-30 minutes. The treated ceramic balls are immersed in an ethanol solution containing a silane coupling agent, shaken at a constant temperature of 40-60° C. for 1-3 hours, taken out and dried at 80-100° C. to obtain surface-modified ceramic microspheres.

9. The fuel cell coolant according to claim 7, characterized in that: The silane coupling agent is at least one of γ-aminopropyltriethoxysilane or γ-glycidyloxypropyltrimethoxysilane, the concentration of the ethanol solution is 1-5wt%, and the mass volume ratio of the ceramic ball to the solution is 1g:10mL.

10. The fuel cell coolant according to claim 7, characterized in that: The composite corrosion inhibitor is premixed according to the following steps: Add sodium silicate, sodium molybdate and nano zinc oxide into a high shear disperser, control the temperature at 30-40°C, and stir at a speed of 1000-3000 r / min for 20-50 minutes to evenly load the nano zinc oxide on the surface of the silicate particles.

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