A salt-fog-resistant carbon fiber composite material and a salt-fog-resistant membrane electrode constructed therefrom

Abstract

The present invention discloses a salt-fog-resistant carbon fiber composite material, which comprises, in sequence, a thin layer of perfluorosulfonic acid resin, a carbon paper substrate, and a microporous layer of carbon powder doped with nano-bismuth oxide. The carbon fiber composite material exhibits excellent absorption of air containing salt fog. Using the carbon fiber composite material as a cathode gas diffusion layer, a salt-fog-resistant membrane electrode can be fabricated. Further assembly into a fuel cell significantly reduces the impact of salt fog on fuel cell performance.

Description

Technical Field

[0001] The invention belongs to the technical field of fuel cells, and in particular relates to a salt-fog resistant carbon fiber composite material and a salt-fog resistant membrane electrode constructed thereof. Background Art

[0002] The shipbuilding industry is a comprehensive sector that provides technical equipment for shipping, marine development, and national defense. It significantly drives the development and export expansion of key industries such as steel, petrochemicals, textiles, equipment manufacturing, and electronic information. Traditional ship propulsion systems, such as diesel engines, steam turbines, and gas turbines, consume diesel fuel to generate power. These systems suffer from the following major issues: low fuel-energy conversion efficiency (approximately 35%); high vibration and noise levels from diesel engines, significantly reducing shipboard comfort; and fuel combustion produces large amounts of greenhouse gases, nitrogen oxides, sulfur oxides, and particulate matter, causing severe environmental pollution. Fossil energy is non-renewable, and existing reserves are limited, making it insufficient to sustain sustainable human development. Therefore, clean, efficient, and sustainable new energy propulsion technologies have become a key development direction for green ships.

[0003] Hydrogen fuel cells are the pinnacle of green power technology in the 21st century. They are power generation devices that directly convert chemical energy into electrical energy, boasting high energy conversion efficiency (40%-60%), low vibration and noise, and zero emissions. Furthermore, hydrogen is a renewable energy source that can be produced from green energy sources such as solar energy, wind energy, water potential, and biomass. Therefore, the application of hydrogen fuel cell propulsion technology on ships can achieve energy efficiency, zero emissions, and improved ship comfort, making it an ideal propulsion device for green ships, meeting the market demand for green shipping.

[0004] In recent years, hydrogen fuel cells have shown rapid development in automotive power applications, while research on their application in ships is still in its infancy. Due to the special operating environment of ships, the power demand, safety, product and material characteristics of fuel cells are different from those of vehicles. In particular, the air at sea contains tiny salt droplets. When air containing salt mist (NaCl) enters the fuel cell, it will affect the performance of its core component, the membrane electrode, and thus its reliability and durability. Studies have shown that Na + It will interact with Pt to form clusters, thereby reducing the activity of Pt and affecting the stability of the cathode oxygen reduction reaction; Cl - Or chloride will be adsorbed on the Pt surface, occupying the catalytic active sites on the Pt surface, resulting in a reduction in the catalytic area, an increase in activation polarization, and ultimately a decline in the overall performance of the battery.

[0005] A common preventative measure for fuel cell applications in marine salt fog environments is to install an air purification device with salt fog filtration capabilities, such as a salt fog filter, at the air inlet. This method primarily utilizes a physical interception or adsorption method for removing salt fog, using non-woven fabric filters, fiber filters, activated carbon filters, and other filter elements. This method has a simple device structure and can filter out large salt fog particles, but it is not ideal for intercepting fine salt fog particles. Therefore, in marine salt fog environments, after the air filtered by the salt fog filter enters the fuel cell system, trace amounts of fine salt fog particles may remain. These particles can enter the membrane electrode (MEA) and poison the catalyst, causing degradation of the MEA performance. Technical measures to prevent trace salt fog in the air at the MEA level are rare in the prior art. In light of this, the present invention provides a salt fog-resistant carbon fiber composite material and a salt fog-resistant MEA constructed therefrom. This carbon fiber composite material can serve as a gas diffusion layer to capture trace amounts of salt fog in the air, thereby protecting the MEA and reducing its impact on hydrogen fuel cell performance. This provides a technical approach for the application and research of hydrogen fuel cells in marine salt fog environments. Summary of the Invention

[0006] The purpose of the present invention is to provide a salt-fog resistant carbon fiber composite material and a salt-fog resistant membrane electrode constructed thereof.

[0007] To achieve the above object, the present invention adopts the following technical solutions:

[0008] A salt fog resistant carbon fiber composite material comprises in sequence a perfluorosulfonic acid resin thin layer, a carbon paper substrate, and a carbon powder microporous layer doped with nano-bismuth oxide.

[0009] The preparation of the carbon fiber composite material comprises the following steps:

[0010] 1) soaking carbon paper in a hydrophobic agent solution, taking it out, drying it, and then calcining it at a high temperature to obtain a hydrophobic carbon paper substrate;

[0011] 2) uniformly dispersing carbon powder, nano-bismuth oxide, and a hydrophobic agent in ethanol as a solvent, coating the resulting dispersion on one side of the carbon paper substrate obtained in step 1), and calcining the dispersion at a high temperature to construct a nano-bismuth oxide-doped carbon powder microporous layer having a chloride ion capture function;

[0012] 3) Evenly spraying an isopropyl alcohol solution of a perfluorosulfonic acid resin on the other side of the carbon paper substrate obtained in step 2), and forming a thin layer of a perfluorosulfonic acid resin with sodium ion absorption performance after drying, thereby obtaining the carbon fiber composite material.

[0013] Furthermore, the hydrophobic agent solution in step 1) is a polytetrafluoroethylene aqueous solution with a mass concentration of 5%-30%.

[0014] Furthermore, the soaking time in step 1) is 10s-60s.

[0015] Furthermore, the high temperature calcination in step 1) is carried out at a temperature of 300° C. to 500° C. and for a time of 30 min to 60 min.

[0016] Furthermore, the mass ratio of carbon powder to nano-bismuth oxide used in step 2) is 1:0.01-0.25.

[0017] Furthermore, in step 2), the hydrophobic agent is polytetrafluoroethylene, and the mass ratio of the hydrophobic agent to the carbon powder is 0.05-0.30:1.

[0018] Furthermore, in step 2), the coating amount of the dispersion (based on dry weight) on the carbon paper substrate is 5%-30% of the mass of the carbon paper substrate.

[0019] Furthermore, the high temperature calcination in step 2) is carried out at a temperature of 300° C. to 500° C. and for a time of 30 min to 60 min.

[0020] Furthermore, the mass concentration of the isopropanol solution of the perfluorosulfonic acid resin in step 3) is 5%-20%; the spraying amount is converted based on the dry weight of the perfluorosulfonic acid resin accounting for 1%-10% of the mass of the carbon powder used.

[0021] When air containing trace amounts of salt mist passes through the carbon fiber composite material, it first passes through a thin layer of perfluorosulfonic acid resin. The sodium ions in the resin react with the sulfonic acid groups on the resin, trapping the sodium ions within the resin and blocking their entry into the catalyst layer and proton exchange membrane. Simultaneously, the remaining air containing trace amounts of salt mist passes through the carbon paper substrate and further enters the microporous layer of carbon powder doped with nano-bismuth oxide. Chloride ions in the remaining air react with the carbon paper substrate to form a BiOCl precipitate, which is adsorbed on the powder, achieving a dechlorination effect. Therefore, the carbon fiber composite material can be used as a cathode gas diffusion layer in the preparation of salt-fog-resistant membrane electrodes.

[0022] Furthermore, the structure of the salt-fog resistant membrane electrode further includes an anode gas diffusion layer, an anode catalyst layer, a proton exchange membrane and a cathode catalyst layer.

[0023] Furthermore, the anode gas diffusion layer is prepared by soaking carbon paper in a solution containing a hydrophobic agent, taking it out, drying it, and then calcining it at high temperature to obtain a hydrophobic carbon paper substrate; then, a mixture solution of carbon powder and a hydrophobic agent is evenly coated on one side of the obtained carbon paper substrate, and then calcined it at high temperature for the second time.

[0024] The solution containing the hydrophobic agent is a polytetrafluoroethylene aqueous solution with a mass concentration of 5%-30%; the temperature of the high-temperature calcination is 300°C-500°C, and the time is 30min-60min; the mass ratio of carbon powder to hydrophobic agent in the mixture solution is 1:0.05-0.30, the hydrophobic agent is polytetrafluoroethylene, and the solvent used is ethanol; the coating amount of the mixture solution on the carbon paper substrate is converted based on the total mass of the carbon powder and the hydrophobic agent accounting for 5%-30% of the mass of the carbon paper substrate; the temperature of the secondary high-temperature calcination is 300°C-500°C, and the time is 30min-60min.

[0025] Furthermore, the anode catalyst layer is formed by coating one side of a proton exchange membrane with a platinum-carbon catalyst and a perfluorosulfonic acid type ionomer mixed in a certain proportion. The cathode catalyst layer is formed by coating the other side of a proton exchange membrane with a platinum-carbon catalyst and a perfluorosulfonic acid type ionomer mixed in a certain proportion.

[0026] When preparing the anode catalyst layer, the mass ratio of the platinum carbon catalyst to the perfluorosulfonic acid type ion polymer is 10:3, and the coating amount is 0.1 mg Pt / cm 2 When preparing the cathode catalyst layer, the mass ratio of the platinum carbon catalyst to the perfluorosulfonic acid type ion polymer is 10:3, and the coating amount is 0.3 mg Pt / cm 2 Perform conversion.

[0027] The present invention has the following beneficial effects:

[0028] The present invention provides a carbon fiber composite material with good absorption effect on salt-fog air. The carbon fiber composite material can be used as a cathode gas diffusion layer to prepare a salt-fog-resistant membrane electrode, and further assembled into a fuel cell, thereby significantly reducing the impact of salt fog on the performance of the fuel cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 Schematic diagram of the structure of the salt spray resistant carbon fiber composite material of the present invention.

[0030] Figure 2 The diagram is a structural diagram of a salt-fog resistant membrane electrode prepared by using the salt-fog resistant carbon fiber composite material of the present invention as a cathode gas diffusion layer.

[0031] Figure 3 The voltage-current density polarization curves of the membrane electrode constructed with different cathode gas diffusion layers in the application example in the discharge test. DETAILED DESCRIPTION

[0032] A salt spray-resistant carbon fiber composite material comprises, in sequence, a perfluorosulfonic acid resin thin layer, a carbon paper substrate, and a carbon powder microporous layer doped with nano-bismuth oxide; the preparation thereof comprises the following steps:

[0033] 1) Soaking carbon paper in a polytetrafluoroethylene aqueous solution having a mass concentration of 5% to 30% for 10 to 60 seconds, then removing the carbon paper, rapidly drying the carbon paper, and calcining the carbon paper at a high temperature of 300° C. to 500° C. for 30 to 60 minutes to obtain a hydrophobic carbon paper substrate;

[0034] 2) uniformly dispersing carbon powder, nano-bismuth oxide, and polytetrafluoroethylene in an ethanol solvent at a mass ratio of 1:0.01-0.25:0.05-0.30, coating the resulting dispersion on one side of the carbon paper substrate obtained in step 1) in an amount calculated by converting the dispersion (by dry weight) to 5%-30% of the mass of the carbon paper substrate, and calcining the dispersion at 300° C.-500° C. for 30 min-60 min to form a carbon powder microporous layer doped with nano-bismuth oxide;

[0035] 3) Evenly spraying a 5%-20% mass concentration of a perfluorosulfonic acid resin isopropyl alcohol solution on the other side of the carbon paper substrate obtained in step 2), wherein the spraying amount is calculated based on the dry weight of the perfluorosulfonic acid resin accounting for 1%-10% of the mass of the carbon powder, and then drying to obtain the carbon fiber composite material.

[0036] In order to make the contents of the present invention easier to understand, the technical solutions of the present invention are further described below in conjunction with specific implementation methods, but the present invention is not limited thereto. Example

[0037] like Figure 1 A salt spray-resistant carbon fiber composite material comprises, from top to bottom, a thin layer of perfluorosulfonic acid resin, a carbon paper substrate, and a microporous layer of carbon powder doped with nano-bismuth oxide. Its preparation includes the following steps:

[0038] 1) Soaking carbon paper in a 10% polytetrafluoroethylene aqueous solution for 15 seconds, then taking it out, quickly drying it, and calcining it at 430°C for 30 minutes to obtain a hydrophobic carbon paper substrate;

[0039] 2) mixing carbon powder, nano-bismuth oxide, and polytetrafluoroethylene in ethanol at a mass ratio of 1:0.08:0.20, and evenly coating the mixture on one side of the carbon paper substrate obtained in step 1) so that the dry weight of the dispersion accounts for 15% of the mass of the carbon paper substrate. The mixture was then calcined at 430° C. for 30 minutes to form a carbon powder microporous layer doped with nano-bismuth oxide;

[0040] 3) Based on the dry weight of the perfluorosulfonic acid resin accounting for 5% of the mass of the carbon powder, a 5% mass concentration of perfluorosulfonic acid resin isopropanol solution was evenly sprayed on the other side of the obtained carbon paper substrate, and the carbon fiber composite material with salt spray resistance was obtained after drying at 80°C for 60 seconds.

[0041] Application Examples

[0042] like Figure 2A salt-fog resistant membrane electrode comprises, in sequence, an anode gas diffusion layer, an anode catalyst layer, a proton exchange membrane, a cathode catalyst layer, and a cathode gas diffusion layer. Its preparation comprises the following steps:

[0043] 1) Carbon paper was soaked in a 10% polytetrafluoroethylene aqueous solution for 15 seconds, then removed, quickly dried, and calcined at 430°C for 30 minutes to obtain a hydrophobic carbon paper substrate. An ethanol dispersion of carbon powder and polytetrafluoroethylene in a mass ratio of 1:0.2 was then evenly coated on one side of the obtained carbon paper substrate, with the coating amount calculated based on the total mass of the carbon powder and polytetrafluoroethylene accounting for 15% of the mass of the carbon paper substrate. The carbon paper substrate was then calcined a second time at 430°C for 30 minutes to obtain an anode gas diffusion layer consisting of the carbon paper substrate and the carbon powder microporous layer.

[0044] 2) Platinum-carbon catalyst and perfluorosulfonic acid type ionomer with a mass ratio of 10:3 were added to a mixture of water and isopropanol (7:3, w / w) to form a mixed solution, and then 0.1 mg Pt / cm 2 The coating amount was evenly coated on one side of the proton exchange membrane to form an anode catalyst layer, and the coating was carried out at a rate of 0.3 mg Pt / cm 2 The mixed solution is evenly coated on the other side of the proton exchange membrane in an amount of coating to form a cathode catalyst layer (the component consisting of the anode catalyst layer, the cathode catalyst layer and the proton exchange membrane is referred to as CCM for short);

[0045] 3) The anode gas diffusion layer obtained in step 1), the CCM obtained in step 1), and the carbon fiber composite material prepared in the embodiment are assembled in sequence, so that the anode catalyst layer is adjacent to the anode gas diffusion layer and the cathode catalyst layer is adjacent to the cathode gas diffusion layer, thereby obtaining a salt spray resistant membrane electrode.

[0046] Bench tests were conducted to verify the salt spray resistance of the constructed salt spray resistant membrane electrode. Membrane electrode samples constructed with different cathode gas diffusion layers (MEA1, a membrane electrode sample constructed using a carbon fiber composite material without a perfluorosulfonic acid resin thin layer and containing only a carbon powder microporous layer (not doped with nano-bismuth oxide) as the cathode gas diffusion layer; MEA2, a membrane electrode sample constructed using a carbon fiber composite material containing a perfluorosulfonic acid resin thin layer and containing only a carbon powder microporous layer (not doped with nano-bismuth oxide) as the cathode gas diffusion layer; MEA3, a membrane electrode sample constructed using a carbon fiber composite material without a perfluorosulfonic acid resin thin layer and containing a carbon powder microporous layer doped with nano-bismuth oxide as the cathode gas diffusion layer; and MEA4, a membrane electrode sample constructed using a cathode gas diffusion layer with salt spray resistance, i.e., a perfluorosulfonic acid resin thin layer and nano-bismuth oxide doped in the microporous layer) were used for comparison. Single cell polarization curve tests were conducted according to the procedures described in Section 6.7 of GB / T 20042.5-2009. The test air contained 20 mg / cm 3The voltage-current density polarization curve was obtained under a back pressure of 0.1 MPa in the air with salt mist. The results are as follows Figure 3 shown.

[0047] from Figure 3 The results show that under the same test conditions:

[0048] (1) Comparison of the discharge performance of a membrane electrode sample (MEA1) constructed with a carbon fiber composite material containing only a carbon powder microporous layer (not doped with nano-bismuth oxide) as the cathode gas diffusion layer, a membrane electrode sample (MEA2) constructed with a carbon fiber composite material containing a perfluorosulfonic acid resin thin layer and only a carbon powder microporous layer (not doped with nano-bismuth oxide) as the cathode gas diffusion layer, and a membrane electrode sample (MEA3) constructed with a carbon fiber composite material containing a carbon powder microporous layer doped with nano-bismuth oxide as the cathode gas diffusion layer shows that the membrane electrodes prepared with a gas diffusion layer having a single perfluorosulfonic acid resin thin layer or a single chloride ion absorption microporous layer have a certain salt spray resistance effect, and the membrane electrode prepared with a single perfluorosulfonic acid resin thin layer has a better salt spray resistance effect than the membrane electrode prepared with a single microporous layer, which means that the influence of sodium ions on the performance of the membrane electrode is greater than that of chloride ions.

[0049] (2) From the comparison of the discharge performance of the salt-fog-resistant membrane electrode sample (MEA4) constructed with the salt-fog-resistant carbon fiber composite material of the embodiment as the cathode gas diffusion layer and MEA1, MEA2 and MEA3, it can be seen that the membrane electrode prepared by using the cathode gas diffusion layer constructed with both a perfluorosulfonic acid resin thin layer and a chloride ion absorption microporous layer has lower sensitivity to air containing salt fog, proving that it has salt-fog-resistant function.

[0050] The above description is only a preferred embodiment of the present invention. All equivalent changes and modifications made according to the scope of the patent application of the present invention should fall within the scope of the present invention.

Claims

1. A salt spray resistant membrane electrode, which comprises an anode gas diffusion layer, an anode catalyst layer, a proton exchange membrane, a cathode catalyst layer and a cathode gas diffusion layer in sequence, characterized in that: A salt-fog-resistant carbon fiber composite material is used as a cathode gas diffusion layer; the salt-fog-resistant carbon fiber composite material sequentially comprises a perfluorosulfonic acid resin thin layer, a carbon paper substrate, and a carbon powder microporous layer doped with nano-bismuth oxide.

2. The salt spray resistant membrane electrode according to claim 1, characterized in that: The preparation of the salt spray resistant carbon fiber composite material comprises the following steps: 1) soaking carbon paper in a hydrophobic agent solution, taking it out, drying it, and then calcining it at a high temperature to obtain a hydrophobic carbon paper substrate; 2) uniformly dispersing carbon powder, nano-bismuth oxide, and a hydrophobic agent in ethanol as a solvent, coating the resulting dispersion on one side of the carbon paper substrate obtained in step 1), and calcining the dispersion at a high temperature to construct a carbon powder microporous layer doped with nano-bismuth oxide; 3) Evenly spraying an isopropyl alcohol solution of a perfluorosulfonic acid resin on the other side of the carbon paper substrate obtained in step 2) to form a thin layer of the perfluorosulfonic acid resin after drying, thereby obtaining the carbon fiber composite material.

3. The salt spray resistant membrane electrode according to claim 2, characterized in that: In step 1), the hydrophobic agent solution is a polytetrafluoroethylene aqueous solution with a mass concentration of 5%-30%; the soaking time is 10s-60s; the high-temperature calcination temperature is 300°C-500°C, and the time is 30min-60min.

4. The salt spray resistant membrane electrode according to claim 2, characterized in that: The mass ratio of carbon powder to nano-bismuth oxide used in step 2) is 1:0.01-0.25; the hydrophobic agent is polytetrafluoroethylene, and the mass ratio of polytetrafluoroethylene to carbon powder is 0.05-0.30:1; the amount of the dispersion coated on the carbon paper substrate is 5%-30% of the mass of the carbon paper substrate; the high-temperature calcination temperature is 300°C-500°C, and the time is 30 minutes-60 minutes.

5. The salt spray resistant membrane electrode according to claim 2, characterized in that: The mass concentration of the isopropanol solution of the perfluorosulfonic acid resin in step 3) is 5%-20%; the spraying amount is calculated based on the dry weight of the perfluorosulfonic acid resin accounting for 1%-10% of the mass of the carbon powder used.

6. The salt spray resistant membrane electrode according to claim 1, characterized in that: The anode gas diffusion layer is prepared by soaking carbon paper in a solution containing a hydrophobic agent, taking it out, drying it, and then calcining it at high temperature to obtain a hydrophobic carbon paper substrate; then uniformly coating a mixture solution of carbon powder and a hydrophobic agent on one side of the obtained carbon paper substrate, and calcining it at high temperature twice.

7. The salt spray resistant membrane electrode according to claim 6, characterized in that: The solution containing the hydrophobic agent is a polytetrafluoroethylene aqueous solution with a mass concentration of 5%-30%; the temperature of the high-temperature calcination is 300°C-500°C, and the time is 30min-60min; the mass ratio of carbon powder to hydrophobic agent in the mixture solution is 1:0.05-0.30, the hydrophobic agent is polytetrafluoroethylene, and the solvent used is ethanol; the coating amount of the mixture solution on the carbon paper substrate is converted based on the total mass of the carbon powder and the hydrophobic agent accounting for 5%-30% of the mass of the carbon paper substrate; the temperature of the secondary high-temperature calcination is 300°C-500°C, and the time is 30min-60min.

8. The salt spray resistant membrane electrode according to claim 1, characterized in that: The anode catalyst layer and the cathode catalyst layer are formed by mixing platinum-carbon catalyst and perfluorosulfonic acid type ion polymer in proportion and coating them on both sides of the proton exchange membrane respectively.

9. The salt spray resistant membrane electrode according to claim 8, characterized in that: When preparing the anode catalyst layer, the mass ratio of the platinum carbon catalyst to the perfluorosulfonic acid type ionomer is 10:3, and the coating amount is 0.1 mg Pt / cm 2 When preparing the cathode catalyst layer, the mass ratio of the platinum carbon catalyst to the perfluorosulfonic acid type ion polymer is 10:3, and the coating amount is 0.3 mg Pt / cm 2 Perform conversion.

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