Anti-attenuation electric pile and fuel cell system

Abstract

The invention provides an anti-attenuation electric pile and a fuel cell system. The anti-attenuation galvanic pile comprises a plurality of single batteries which are stacked in sequence, wherein each single battery comprises a bipolar plate, electrode assemblies arranged on the two sides of the bipolar plate and a proton exchange membrane located between the two electrode assemblies; the electrode assembly comprises a catalyst layer and a gas diffusion layer, and the catalyst layer is arranged between the proton exchange membrane and the gas diffusion layer; the bipolar plate is made of a metal material of which the surface is plated with an anti-corrosion coating, and the anti-corrosion coating is a carbon nanotube-polytetrafluoroethylene composite coating; nanoscale cerium dioxide particles are added into the catalyst layer, and the particle size of the nanoscale cerium dioxide particles is 5-20 nm. According to the anti-attenuation galvanic pile and the fuel cell system provided by the invention, the bipolar plate and the catalyst layer are improved, so that the anti-attenuation performance of the galvanic pile can be effectively improved, and the service life of the fuel cell system can be further prolonged.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of fuel cells, and particularly relates to an anti-degradation stack and a fuel cell system. BACKGROUND

[0002] As a high-efficiency and environmentally-friendly energy conversion device, fuel cells have a broad application prospect in the fields of portable power supply, transportation and fixed power generation. However, due to the influence of factors such as electrochemical corrosion, mechanical stress, temperature change and reactant impurities, the performance of fuel cell stacks is prone to degradation during long-term operation, which seriously restricts the service life and reliability of fuel cells.

[0003] At present, in the prior art, in order to solve the problem of degradation of fuel cell stacks, methods such as improving electrode materials, optimizing cell structures or adding protective agents are usually adopted. However, these methods still have problems such as limited anti-degradation effect, high cost or complex process in practical application, and it is difficult to meet the demand for long-term stable operation of fuel cells. Therefore, it is necessary to provide a new anti-degradation stack and fuel cell system to solve the above technical problems. SUMMARY

[0004] The technical problem solved by the application is to provide an anti-degradation stack and a fuel cell system which can effectively improve the anti-degradation performance of the stack by improving the bipolar plate and the catalyst layer, thereby prolonging the service life of the fuel cell system.

[0005] To solve the above technical problems, the anti-degradation stack provided by the application comprises: a plurality of single cells stacked in sequence, each single cell comprising a bipolar plate, an electrode assembly arranged on both sides of the bipolar plate and a proton exchange membrane located between the two electrode assemblies.

[0006] The electrode assembly comprises a catalyst layer and a gas diffusion layer, and the catalyst layer is arranged between the proton exchange membrane and the gas diffusion layer.

[0007] The bipolar plate is made of a metal material plated with an anti-corrosion coating on the surface, and the anti-corrosion coating is a carbon nanotube-polytetrafluoroethylene composite coating.

[0008] The catalyst layer is added with nano-sized cerium dioxide particles, the particle size of the nano-sized cerium dioxide particles is 5-20 nm, and the mass fraction of the nano-sized cerium dioxide particles in the catalyst layer is 5%-15%.

[0009] As a further scheme of the application, the metal material is titanium alloy or stainless steel, the preparation method of the carbon nanotube-polytetrafluoroethylene composite coating comprises four steps of dispersion liquid preparation, substrate treatment and immersion, drying treatment and high-temperature sintering, and the preparation process of the dispersion liquid is as follows:

[0010] (1). Carbon nanotubes are uniformly dispersed in polytetrafluoroethylene emulsion and ultrasonically treated for 30-60 minutes at a frequency of 20-40kHz using an ultrasonic dispersion device.

[0011] (2). The cavitation effect generated by ultrasound can effectively break up carbon nanotube aggregates, so that they form a stable system with uniform dispersion in the emulsion. After completion, a dispersion with good flowability can be obtained.

[0012] As a further aspect of the present invention, the substrate treatment and impregnation process is as follows:

[0013] (1) Select bipolar plate substrate and pre-treat its surface by degreasing and grinding to remove surface oil and impurities and increase its surface roughness, which can improve coating adhesion.

[0014] (2) Immerse the pretreated bipolar plate completely in the prepared dispersion and let it stand for 5-10 minutes to allow the dispersion to fully adhere to the substrate surface. Then slowly remove it to avoid uneven liquid dripping affecting the coating thickness.

[0015] As a further aspect of the present invention, the drying process involves placing the impregnated bipolar plate in a forced-air drying oven, setting the temperature to 100-150°C, and drying for 2-4 hours. During this stage, the carbon nanotubes and polytetrafluoroethylene can be initially solidified on the substrate surface by gradually evaporating the solvent in the dispersion, thus forming a wet coating with a certain strength.

[0016] The high-temperature sintering process involves transferring the dried bipolar plate into a high-temperature sintering furnace and sintering it at 350-400℃ for 1-2 hours. Under high temperature, the polytetrafluoroethylene molecular chains fully melt and rearrange, and can form a tight cross-linked structure with carbon nanotubes. Therefore, a dense, uniform carbon nanotube-polytetrafluoroethylene composite coating with excellent anti-attenuation properties can be formed on the surface of the bipolar plate.

[0017] As a further aspect of the present invention, the method for preparing the catalyst layer is as follows:

[0018] (1). The catalyst powder, nano-sized cerium dioxide particles, binder and solvent are mixed and stirred evenly to form a slurry;

[0019] (2) The slurry is coated on the surface of the proton exchange membrane and dried to form the catalyst layer. The catalyst powder is a platinum carbon catalyst or a platinum alloy catalyst.

[0020] The present invention also provides a fuel cell system, characterized in that it includes an anti-degradation fuel cell stack as described in claim 1, a hydrogen supply system, an air supply system, a cooling system, and a control system, wherein the hydrogen supply system is used to supply hydrogen to the anode of the anti-degradation fuel cell stack, the air supply system is used to supply air to the cathode of the anti-degradation fuel cell stack, the cooling system is used to regulate the operating temperature of the anti-degradation fuel cell stack, and the control system is used to control the operation of the hydrogen supply system, the air supply system, and the cooling system.

[0021] As a further embodiment of the present invention, the hydrogen supply system comprises a hydrogen storage tank, a hydrogen pressure reducing valve, a hydrogen circulation pump, and related pipelines. The hydrogen storage tank is used to store high-purity hydrogen, the hydrogen pressure reducing valve can precisely adjust the hydrogen pressure according to the requirements of the fuel cell stack, and the hydrogen circulation pump circulates unreacted hydrogen back to the anode to improve hydrogen utilization. Through precise control, the system continuously supplies hydrogen with stable pressure and flow rate to the anode of the anti-fading fuel cell stack, ensuring the continuous progress of the electrochemical reaction.

[0022] As a further embodiment of the present invention, the air supply system includes an air compressor, an air filter, and a humidity regulator. The air filter can effectively filter impurities in the air to prevent them from entering the fuel cell stack and affecting its performance. The air compressor is responsible for compressing the filtered air and delivering it to the fuel cell stack cathode. Pressure and flow control ensure a sufficient oxygen supply. The humidity regulator adjusts the air humidity according to the fuel cell stack operating conditions to create suitable environmental conditions for the electrochemical reaction.

[0023] As a further aspect of the present invention, the cooling system adopts a liquid-cooled circulation architecture, which consists of a radiator, a coolant pump, a temperature sensor, and cooling pipes. The temperature sensor monitors the operating temperature of the anti-degradation stack in real time and feeds the data back to the control system. When the stack temperature is too high, the coolant pump accelerates to deliver the heated coolant to the radiator for heat dissipation and cooling. The cooled liquid then flows back to the stack, thereby achieving stable regulation of the stack operating temperature and avoiding performance degradation or damage to the stack due to excessive temperature.

[0024] As a further aspect of the present invention, the control system is built on an advanced PLC or ECU, and collects pressure and flow data of the hydrogen supply system, oxygen concentration and pressure parameters of the air supply system, and temperature information of the cooling system in real time through a sensor network. Then, according to a preset control strategy and algorithm, the operating parameters of the hydrogen supply system, air supply system and cooling system are dynamically adjusted to achieve coordinated work between the subsystems and ensure that the fuel cell system can operate safely, efficiently and stably under different operating conditions.

[0025] Compared with related technologies, the anti-degradation stack and fuel cell system provided by the present invention have the following beneficial effects:

[0026] 1. This invention improves the corrosion resistance of bipolar plates by setting a carbon nanotube-polytetrafluoroethylene composite coating on the surface of the bipolar plates, reduces corrosion loss of the bipolar plates during fuel cell operation, and thus extends the service life of the fuel cell stack.

[0027] 2. This invention improves the electrochemical performance of the catalyst layer by adding nano-sized cerium dioxide particles to the catalyst layer, utilizing the excellent oxygen storage and release capabilities of cerium dioxide, thereby reducing catalyst agglomeration and poisoning, enhancing the stability of the catalyst layer, and ultimately reducing the performance degradation rate of the fuel cell stack. Attached Figure Description

[0028] To facilitate understanding by those skilled in the art, the present invention will be further described below with reference to the accompanying drawings.

[0029] Figure 1 This is a schematic diagram of the structure of a single battery of the present invention;

[0030] Figure 2 A comparative illustration of experimental data for the anti-degradation fuel cell stack prepared in this invention and conventional fuel cell stacks without anti-corrosion coating and without a catalyst layer containing nano-sized cerium dioxide particles. Figure 2 . Detailed Implementation

[0031] To make the objectives, technical solutions, and advantages of the present invention clear and complete, the embodiments of the present invention will be further described in detail below. It should be understood that the specific embodiments described herein are some embodiments of the present invention, but not all embodiments, and are only used to explain the embodiments of the present invention, and are not intended to limit the embodiments of the present invention. All other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0032] Example 1

[0033] A method for fabricating an anti-degradation electric stack includes the following steps:

[0034] (1). Bipolar plate fabrication:

[0035] 1) Titanium alloy was selected as the bipolar plate substrate, and carbon nanotubes were dispersed in polytetrafluoroethylene emulsion and ultrasonically dispersed for 30 min to form a uniform dispersion with a carbon nanotube mass fraction of 5%.

[0036] 2) The titanium alloy bipolar plate substrate is immersed in the dispersion solution, then dried at 100℃ for 2 hours, and finally sintered at 350℃ for 1 hour to form a carbon nanotube-polytetrafluoroethylene composite coating.

[0037] (2). Catalyst layer preparation:

[0038] 1) Mix platinum-carbon catalyst (Pt loading of 40%), nano-sized cerium dioxide particles (particle size 5nm, mass fraction 5%), perfluorosulfonic acid resin binder and ethanol solvent, and stir evenly to form a slurry;

[0039] 2) The slurry was coated onto the surface of a proton exchange membrane (Nafion 117), and after drying, a catalytic layer was formed with a thickness of 20 μm;

[0040] (3). Single cell assembly: The prepared bipolar plates, electrode components (catalytic layer and gas diffusion layer) and proton exchange membrane are assembled in the order of bipolar plates - gas diffusion layer - catalytic layer - proton exchange membrane - catalytic layer - gas diffusion layer - bipolar plates to form a single cell;

[0041] (4) Stack assembly: Stack 10 single cells in sequence and fasten them with bolts to form an anti-degradation stack.

[0042] The assembly of a fuel cell system includes the following steps:

[0043] The anti-degradation fuel cell stack is connected to a hydrogen supply system, an air supply system, a cooling system, and a control system to form a fuel cell system. The hydrogen supply system includes a hydrogen cylinder, a pressure reducing valve, and a mass flow meter to supply pure hydrogen to the anode of the fuel cell stack. The air supply system includes an air compressor, a humidifier, and a filter to supply dry, clean air to the cathode of the fuel cell stack. The cooling system includes a water pump, a radiator, and a temperature sensor to regulate the operating temperature of the fuel cell stack. The control system includes a controller and sensors to monitor and control the operating parameters of the fuel cell system in real time.

[0044] Example 2

[0045] A method for fabricating an anti-degradation electric stack includes the following steps:

[0046] (1). Bipolar plate fabrication:

[0047] 1) Stainless steel was selected as the bipolar plate substrate, and carbon nanotubes were dispersed in polytetrafluoroethylene emulsion and ultrasonically dispersed for 60-30 min to form a uniform dispersion with a carbon nanotube mass fraction of 10%.

[0048] 2) The stainless steel bipolar plate substrate is immersed in the dispersion solution, then dried at 150°C for 42 hours, and finally sintered at 400°C for 1 hour to form a carbon nanotube-polytetrafluoroethylene composite coating.

[0049] (2). Catalyst layer preparation:

[0050] 1) Mix platinum-cobalt alloy catalyst (Pt:Co = 3:1), nano-sized cerium dioxide particles (particle size 20nm, mass fraction 15%), perfluorosulfonic acid resin binder and isopropanol solvent, and stir evenly to form a slurry;

[0051] 2) The slurry was coated onto the surface of a proton exchange membrane (Nafion 115), and after drying, a catalytic layer was formed with a thickness of 30 μm;

[0052] (3). The single cell assembly and stack assembly steps are the same as in Example 1, except that the stack is composed of 20 single cells instead of 10.

[0053] The assembly steps of a fuel cell system are the same as those of the fuel cell system assembly steps in Example 1.

[0054] Example 3

[0055] A method for fabricating an anti-degradation electric stack includes the following steps:

[0056] (1). Bipolar plate preparation: Titanium alloy was selected as the bipolar plate substrate, and the mass fraction of carbon nanotubes in the carbon nanotube dispersion was 8%. Other preparation steps were the same as in Example 1.

[0057] (2). Catalytic layer preparation: The mass fraction of nano-sized cerium dioxide particles is 10%, and the particle size is 10 nm. Other preparation steps are the same as in Example 1.

[0058] (3). The single cell assembly and stack assembly steps are the same as in Example 1, except that the stack is composed of 15 single cells instead of 10.

[0059] The assembly steps of a fuel cell system are the same as those of the fuel cell system assembly steps in Example 1.

[0060] As can be seen from the above embodiments, the anti-degradation stack and fuel cell system of the present invention can achieve good anti-degradation performance and stable operation by rationally selecting bipolar plate materials and coatings, catalyst layer components and preparation processes.

[0061] In summary, the present invention provides an anti-degradation fuel cell stack and a fuel cell system comprising the same. By improving the bipolar plates and the catalyst layer, the anti-degradation performance of the fuel cell stack can be effectively improved, thereby extending the service life of the fuel cell system.

[0062] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A damping-resistant fuel cell stack, characterized in that, include: Multiple single cells stacked sequentially, each single cell including a bipolar plate, electrode assemblies disposed on both sides of the bipolar plate, and a proton exchange membrane located between the two electrode assemblies; The electrode assembly includes a catalytic layer and a gas diffusion layer, wherein the catalytic layer is disposed between the proton exchange membrane and the gas diffusion layer; The bipolar plate is made of a metal material with an anti-corrosion coating on its surface. The anti-corrosion coating is a carbon nanotube-polytetrafluoroethylene composite coating. The catalyst layer contains nano-sized cerium dioxide particles with a particle size of 5-20 nm and a mass fraction of 5%-15% in the catalyst layer.

2. The anti-attenuation stack according to claim 1, characterized in that: The metal material is titanium alloy or stainless steel. The preparation method of the carbon nanotube-polytetrafluoroethylene composite coating includes four steps: dispersion preparation, substrate treatment and impregnation, drying treatment, and high-temperature sintering. The preparation process of the dispersion is as follows: (1). Carbon nanotubes are uniformly dispersed in polytetrafluoroethylene emulsion and ultrasonically treated for 30-60 minutes at a frequency of 20-40kHz using an ultrasonic dispersion device. (2). The cavitation effect generated by ultrasound can effectively break up carbon nanotube aggregates, so that they form a stable system with uniform dispersion in the emulsion. After completion, a dispersion with good flowability can be obtained.

3. The anti-attenuation stack according to claim 2, characterized in that: The substrate treatment and impregnation process is as follows: (1) Select bipolar plate substrate and pre-treat its surface by degreasing and grinding to remove surface oil and impurities and increase its surface roughness, which can improve coating adhesion. (2) Immerse the pretreated bipolar plate completely in the prepared dispersion and let it stand for 5-10 minutes to allow the dispersion to fully adhere to the substrate surface. Then slowly remove it to avoid uneven liquid dripping affecting the coating thickness.

4. The anti-attenuation stack according to claim 2, characterized in that: The drying process involves placing the impregnated bipolar plate in a forced-air drying oven, setting the temperature to 100-150℃, and drying for 2-4 hours. During this stage, the carbon nanotubes and polytetrafluoroethylene can be initially solidified on the substrate surface by gradually evaporating the solvent in the dispersion, forming a wet coating with a certain strength. The high-temperature sintering process involves transferring the dried bipolar plate into a high-temperature sintering furnace and sintering it at 350-400℃ for 1-2 hours. Under high temperature, the polytetrafluoroethylene molecular chains fully melt and rearrange, and can form a tight cross-linked structure with carbon nanotubes. Therefore, a dense, uniform carbon nanotube-polytetrafluoroethylene composite coating with excellent anti-attenuation properties can be formed on the surface of the bipolar plate.

5. The anti-attenuation stack according to claim 2, characterized in that: The method for preparing the catalyst layer is as follows: (1). The catalyst powder, nano-sized cerium dioxide particles, binder and solvent are mixed and stirred evenly to form a slurry; (2) The slurry is coated on the surface of the proton exchange membrane and dried to form the catalyst layer. The catalyst powder is a platinum carbon catalyst or a platinum alloy catalyst.

6. A fuel cell system, characterized in that, The system includes the anti-degradation fuel cell stack as described in claim 1, as well as a hydrogen supply system, an air supply system, a cooling system, and a control system. The hydrogen supply system is used to supply hydrogen to the anode of the anti-degradation fuel cell stack, the air supply system is used to supply air to the cathode of the anti-degradation fuel cell stack, the cooling system is used to regulate the operating temperature of the anti-degradation fuel cell stack, and the control system is used to control the operation of the hydrogen supply system, the air supply system, and the cooling system.

7. The fuel cell system according to claim 6, characterized in that: The hydrogen supply system consists of a hydrogen storage tank, a hydrogen pressure reducing valve, a hydrogen circulation pump, and related pipelines. The hydrogen storage tank is used to store high-purity hydrogen, the hydrogen pressure reducing valve can precisely adjust the hydrogen pressure according to the needs of the fuel cell stack, and the hydrogen circulation pump circulates unreacted hydrogen back to the anode to improve hydrogen utilization. Through precise control, the system continuously supplies hydrogen with stable pressure and flow to the anode of the anti-fading fuel cell stack, ensuring the continuous progress of the electrochemical reaction.

8. The fuel cell system according to claim 6, characterized in that: The air supply system includes an air compressor, an air filter, and a humidity regulator. The air filter can effectively filter impurities in the air to prevent them from entering the fuel cell stack and affecting its performance. The air compressor is responsible for compressing the filtered air and delivering it to the fuel cell stack cathode. Pressure and flow control ensure a sufficient oxygen supply. The humidity regulator adjusts the air humidity according to the fuel cell stack operating conditions to create suitable environmental conditions for the electrochemical reaction.

9. The fuel cell system according to claim 6, characterized in that: The cooling system adopts a liquid-cooled circulation architecture, which consists of a radiator, a coolant pump, a temperature sensor, and cooling pipes. The temperature sensor monitors the operating temperature of the anti-degradation stack in real time and feeds the data back to the control system. When the stack temperature is too high, the coolant pump accelerates to deliver the heated coolant to the radiator for heat dissipation and cooling. The cooled liquid then flows back to the stack, thereby achieving stable regulation of the stack operating temperature and preventing the stack performance from degrading or being damaged due to excessive temperature.

10. The fuel cell system according to claim 6, characterized in that: The control system is built on an advanced PLC or ECU. It collects pressure and flow data of the hydrogen supply system, oxygen concentration and pressure parameters of the air supply system, and temperature information of the cooling system in real time through a sensor network. Then, according to the preset control strategy and algorithm, it dynamically adjusts the operating parameters of the hydrogen supply system, air supply system, and cooling system to achieve coordinated work between the subsystems and ensure that the fuel cell system can operate safely, efficiently, and stably under different operating conditions.

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