Off-line loading device for studying thermal decay of fuel cell catalyst layers and method of use

Abstract

The application relates to an off-line loading device for studying thermal attenuation of a fuel cell catalytic layer and a use method, and realizes thermal attenuation of the catalytic layer in an external heat source heating mode. The off-line loading clamp comprises a clamp base, a pressure component and a pressure adjusting knob, and is used for clamping and fixing a sample to be measured; the temperature control assembly comprises a heating component, a temperature sensor and a temperature digital display component, and is used for monitoring and visualizing the internal temperature of the sample to be measured; the pressure control assembly comprises a pressure sensor and a pressure digital display component, and is used for monitoring and visualizing the bearing pressure of the sample to be measured. Compared with the prior art, the application excludes the interference of chemical degradation in in-situ testing, can realize accurate regulation of key factors influencing the catalytic layer thermal attenuation process such as the bearing pressure, the internal temperature and the internal humidity of the sample, and has the advantages of simple structure and convenient operation.

Description

Technical Field

[0001] This invention relates to the field of proton exchange membrane fuel cell durability testing technology, and in particular to an offline loading device and method for studying the thermal degradation of fuel cell catalyst layers. Background Technology

[0002] Faced with increasingly severe environmental and energy security challenges, proton exchange membrane fuel cells (PEMFCs), with their advantages of high energy density, fast start-up speed, and zero emissions, have become a promising new generation of clean energy power devices. However, one of the obstacles currently limiting the development of PEMFCs is their short lifespan. As the site of electrochemical reactions, the performance of the catalyst layer directly determines the amount of electrical energy output from the fuel cell. Therefore, addressing the durability issue of the catalyst layer has become the primary choice for improving fuel cell durability. During fuel cell operation, heat is generated within the catalyst layer due to the electrochemical reaction process. Poor heat dissipation can lead to localized overheating, resulting in thermal decay of the components. Clarifying the thermal decay mechanism of the catalyst layer components is of great significance for extending the lifespan of fuel cells.

[0003] In addition, electrochemical reactions can induce chemical degradation of catalyst layer components, such as degradation of ionomers by free radical attack, corrosion of carbon supports due to high potential, and oxidation of platinum catalysts. This will affect the heat generation process inside the catalyst layer. Furthermore, the thermal decay process of components after chemical degradation will be quite different from that of components alone. Online testing to study the thermal decay mechanism of the catalyst layer will be interfered with by the chemical degradation of the catalyst layer.

[0004] Therefore, it is necessary to develop an offline loading device to analyze the thermal decay mechanism of catalyst layer components without the influence of chemical degradation. Summary of the Invention

[0005] The purpose of this invention is to overcome the defects of the prior art by providing an offline loading device and method for studying the thermal decay of fuel cell catalyst layers. By eliminating the interference of chemical degradation in in-situ testing, it enables precise control of key factors affecting the thermal decay process of the catalyst layer.

[0006] The objective of this invention can be achieved through the following technical solutions:

[0007] This invention provides an offline loading device for studying the thermal decay of fuel cell catalyst layers, including a temperature and humidity chamber, an offline loading fixture, a temperature control component, and a pressure control component;

[0008] The offline loading fixture, from bottom to top, includes a fixture base, a pressure component, and a pressure adjustment knob, which are used to clamp and fix the sample to be tested.

[0009] The temperature control component includes a heating element, a temperature sensor, and a temperature display element, used to monitor and visualize the internal temperature of the sample to be tested. The temperature sensor and the temperature display element are electrically connected.

[0010] The pressure control component includes a pressure sensor and a pressure digital display component for monitoring and visualizing the pressure that the sample under test can withstand. The pressure digital display component is electrically connected to the pressure sensor.

[0011] The offline loading fixture, the sample to be tested, the temperature control component, and the pressure control component are placed inside the temperature and humidity chamber.

[0012] Furthermore, the fixture base includes a sample boss and a pressure adjusting knob boss, and the pressure adjusting knob boss is provided with a threaded hole for installing the pressure adjusting knob;

[0013] The pressure regulating knob includes a knob head and a knob rod, the knob rod being provided with an external thread that matches the threaded hole;

[0014] The pressure component is an upper pressure block;

[0015] The heating component is a heating rod, and there are two heating rods and two temperature sensors, which are located in the upper pressure block and the sample protrusion, respectively.

[0016] Furthermore, the pressure sensor is a thin-film pressure sensor, which is fixed to the sample protrusion.

[0017] Furthermore, the upper pressure block is a cuboid, and the upper pressure block has upper temperature sensor holes and upper heating rod holes on its two sides near the sample to be tested.

[0018] Furthermore, the upper temperature sensor hole is used to install a first temperature sensor, which is used to detect the temperature of the upper surface of the sample to be tested; the upper heating rod hole is used to install a first heating rod, which is used to heat the upper surface of the sample to be tested.

[0019] Furthermore, the sample boss is a square boss, located at the center of the fixture base. The sample boss has a lower temperature sensor hole and a lower heating rod hole on both sides. The lower temperature sensor hole is used to install a second temperature sensor, which is used to detect the temperature of the lower surface of the sample to be tested. The lower heating rod hole is used to install a second heating rod, which is used to heat the lower surface of the sample. The sample to be tested is placed on the sample boss.

[0020] Furthermore, the pressure regulating knob boss is located at the center of the fixture base, and rectangular through holes are provided around the sides of the pressure regulating knob boss. The rectangular through holes are used to reserve clamping space for the sample to be tested and to achieve full contact between the sample to be tested and the external environment.

[0021] Furthermore, the pressure regulating knob boss is also provided with an upper pressure block positioning hole, which is used to install the upper pressure block.

[0022] Furthermore, the sample to be tested has polytetrafluoroethylene films on both sides and a catalyst layer in the middle. Both the polytetrafluoroethylene films and the catalyst layer are squares of the same size, and the size of the sample to be tested is the same as the size of the sample boss.

[0023] This invention also provides a method for using an offline loading device to study the thermal degradation of a fuel cell catalyst layer, comprising the following steps:

[0024] S1: Samples for testing the thermal attenuation of the catalyst layer were prepared by spraying or blade transfer.

[0025] S2: First, assemble the offline loading fixture and temperature control components, and adjust the required temperature; then, place the pressure sensor and the sample to be tested prepared in S1 into the container, and assemble the pressure control components again, adjusting the required pressure; finally, place the assembled components into a temperature and humidity chamber, adjust the ambient humidity, and complete the assembly of the offline loading device.

[0026] S3: Conduct offline thermal decay durability experiments on the sample to be tested in the device assembled in S2. Analyze the experimental results using relevant characterization techniques and establish a database of thermal decay indexes for the catalyst layer, providing basic data for elucidating the thermal decay mechanism of the catalyst layer.

[0027] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0028] 1. This invention proposes an offline loading device for studying the thermal decay of the catalyst layer in fuel cells. It eliminates the interference of chemical degradation of the catalyst layer in online testing and realizes offline loading of pure thermal decay of the catalyst layer in proton exchange membrane fuel cells.

[0029] 2. This invention designs an offline loading fixture for the thermal decay of proton exchange membrane catalyst layers. The offline loading fixture has a simple structure and composition, and can achieve precise control of key factors affecting the thermal decay process of the catalyst layer, such as the pressure, internal temperature and internal humidity of the sample. It is easy to operate.

[0030] 3. The present invention designs a sample composition that undergoes thermal decay of the catalyst layer as follows: the two sides are polytetrafluoroethylene membranes as substrates and the catalyst layer is sandwiched in the middle. This avoids the interference of the thermal decay of the proton exchange membrane / gas diffusion layer as substrate on the thermal decay process of the catalyst layer. Moreover, the catalyst layer is easy to peel off after offline loading, which facilitates subsequent offline testing and characterization. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of an offline loading device for studying the thermal degradation of a fuel cell catalyst layer;

[0032] Figure 2 This is a three-dimensional schematic diagram of the offline loading fixture in Example 1;

[0033] Figure 3 This is a front view of the fixture base in Example 1;

[0034] Figure 4 This is a top view of the fixture base in Example 1;

[0035] Figure 5 This is a side view of the fixture base in Example 1;

[0036] Figure 6 This is a front view of the upper pressure block in Example 1;

[0037] Figure 7 This is a side view of the upper pressure block in Example 1;

[0038] Figure 8 This is a top view of the upper pressure block in Example 1;

[0039] Figure 9 This is a front view of the pressure regulating knob in Example 1;

[0040] Figure 10 This is a side view of the pressure regulating knob in Example 1;

[0041] Figure 11 This is a top view of the pressure regulating knob in Example 1;

[0042] Figure 12 This is a front view of the sample to be tested in Example 1;

[0043] Figure 13 This is a side view of the sample to be tested in Example 1;

[0044] Figure 14 This is a top view of the sample to be tested in Example 1.

[0045] Figure 1 Explanation of Chinese markings:

[0046] 1'-Temperature and humidity chamber, 2'-Offline loading fixture, 3'-Temperature control component, 4'-Pressure control component, 301-Digital temperature display component, 302-First temperature sensor, 303-Second temperature sensor, 304-First heating rod, 305-Second heating rod, 401-Digital pressure display component, 402-Thin film pressure sensor;

[0047] Figure 2 Explanation of Chinese markings:

[0048] 1-Clamp base, 2-Upper pressure block, 3-Pressure adjustment knob;

[0049] Figure 3 Explanation of Chinese markings:

[0050] 4-Threaded hole, 5-Locking hole, 6-Sample boss;

[0051] Figure 4 Explanation of Chinese markings:

[0052] 7 - Lower temperature sensor hole; 8 - Lower heating rod hole;

[0053] Figure 5 Explanation of Chinese markings:

[0054] 9-Rectangular through hole, 10-Pressure adjustment knob boss;

[0055] Figure 6 Explanation of Chinese markings:

[0056] 11-Upper pressure block;

[0057] Figure 8 Explanation of Chinese markings:

[0058] 12 - Upper temperature sensor hole; 13 - Upper heating rod hole;

[0059] Figure 9 Explanation of Chinese markings:

[0060] 14 - External thread, 15 - Knob head;

[0061] Figure 11 Explanation of Chinese markings:

[0062] 16- Knob lever;

[0063] Figure 12 Explanation of Chinese markings:

[0064] 17-Catalyst layer, 18-Polytetrafluoroethylene film. Detailed Implementation

[0065] The following examples illustrate specific implementations of the present invention. These examples are carried out based on the solution described in the present invention, and provide detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following examples.

[0066] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. Component models, material names, connection structures, and other features not explicitly described in this technical solution are considered common technical features disclosed in the prior art.

[0067] Example 1

[0068] This invention provides an offline loading device for studying the thermal degradation of fuel cell catalyst layers, such as... Figure 1 As shown, an external heat source is used to achieve thermal decay of the catalyst layer, comprising a temperature and humidity chamber 1', an offline loading fixture 2', a temperature control component 3', and a pressure control component 4'. The offline loading fixture 2' clamps and fixes the sample to be tested; the pressure control component 4' monitors the pressure exerted on the sample, simulating the assembly pressure experienced by the catalyst layer during actual fuel cell operation; the temperature control component 3' monitors the internal temperature of the sample, simulating the different temperature environments faced by the catalyst layer during actual fuel cell operation; and the temperature and humidity chamber 1' monitors the internal humidity of the sample, simulating the different humidity environments faced by the catalyst layer during actual fuel cell operation. The offline loading fixture 2', temperature control component 3', and pressure control component 4' are assembled sequentially and placed inside the temperature and humidity chamber 1'.

[0069] The offline loading fixture 2' is manufactured using materials with good thermal conductivity, machinability, and pressure resistance. From bottom to top, it includes a fixture base 1, an upper pressure block 2, and a pressure adjusting knob 3. Figure 2 As shown. Figures 3-5 The figures show the front view, top view, and side view of the fixture base. The fixture base 1 includes a sample boss 6 and a pressure regulating knob boss 10. The fixture base 1 has a threaded hole 4. The sample boss 6 is a square boss located at the center of the fixture base 1. The sample to be tested is placed on the sample boss 6, which has a lower temperature sensor hole 7 and a lower heating rod hole 8 on both sides. The lower temperature sensor hole 7 is used to install a second temperature sensor 303, which detects the temperature of the lower surface of the sample to be tested. The lower heating rod hole 8 is used to install a second heating rod 305, which heats the lower surface of the sample to be tested. The pressure regulating knob boss 10 is also located at the center of the fixture base 1, with rectangular through holes 9 on its sides to provide space for sample clamping and ensure sufficient contact between the sample and the external environment. The pressure regulating knob boss 10 has a threaded hole 4 and an upper pressure block positioning hole 5. The threaded hole 4 is used to install the pressure regulating knob 3, and the upper pressure block positioning hole 5 is used to install the upper pressure block 2.

[0070] Figures 6-8 The figures show the front view, side view, and top view of the upper pressure block. The upper pressure block 2 is a cuboid used to transmit the pressure applied to the sample by the pressure adjustment knob 3 and the threaded hole 4. The upper temperature sensor hole 12 and the upper heating rod hole 13 are provided on the two sides near the sample. The upper temperature sensor hole 12 is used to install the first temperature sensor 302, which detects the temperature of the upper surface of the sample. The upper heating rod hole 13 is used to install the first heating rod 304, which heats the upper surface of the sample.

[0071] Figures 9-11 The front view, side view and top view of the pressure regulating knob are shown in the figure. The pressure regulating knob 3 includes a knob head 15 and a knob rod 16. The knob rod 16 is provided with an external thread 14, which is used in conjunction with the threaded hole 4 opened in the fixture base to realize the supply of pressure to the sample. The knob head 15 is for the convenience of the knob rod 16 to perform the rotation operation of applying pressure to the sample to be tested.

[0072] The pressure control component 4' includes a thin-film pressure sensor 402 and a pressure digital display component 401. The thin-film pressure sensor 402 is fixed between the sample protrusion 6 and the sample to be tested. The pressure digital display component visualizes the pressure exerted on the sample and is electrically connected to the pressure sensor 402 to monitor the pressure exerted on the sample.

[0073] The temperature control component 3' includes a heating rod, a temperature sensor, and a digital temperature display component 301. Two heating rods and two temperature sensors are provided: a first temperature sensor 302 and a first heating rod 304 are located on the upper pressure block 2, and a second temperature sensor 303 and a second heating rod 305 are located on the sample protrusion 6. The two heating rods serve as heat sources to heat the catalyst layer 17; the two temperature sensors are used to monitor the internal temperature of the sample under test; the digital temperature display component 301 visualizes the internal temperature of the sample under test and, in conjunction with the heating rods and temperature sensors, enables comprehensive monitoring of the internal temperature of the sample under test.

[0074] The temperature and humidity chamber 1' is the source of humidity control inside the sample. During the test, the offline loading fixture 2', the sample to be tested, the pressure sensor 402, two heating rods and two temperature sensors are assembled and placed in the temperature and humidity chamber 1' in sequence.

[0075] Figures 12-14The figures show the front, side, and top views of the sample to be tested. The sample has polytetrafluoroethylene (PTFE) films 18 on both sides and a catalyst layer 17 in the middle, prepared by transfer printing or spraying. Both the PTFE films 18 and the catalyst layer 17 are squares of the same size, and the sample dimensions are the same as the sample boss 6. Precise control of the pressure, internal temperature, and internal humidity of the sample is achieved through the connection of the offline loading fixture 2' with the pressure control component 4', temperature control component 3', and temperature and humidity chamber 1', further enabling offline loading for the pure thermal decay of the proton exchange membrane fuel cell catalyst layer.

[0076] This invention also provides a method for using an offline loading device to study the thermal degradation of a fuel cell catalyst layer, comprising the following steps:

[0077] S1: A catalyst layer 17 is deposited on a polytetrafluoroethylene film 18 using a spraying / scalpel transfer method. Then, a polytetrafluoroethylene film 18 is horizontally stacked on the catalyst layer to obtain a sample for testing the thermal decay of the catalyst layer. The two polytetrafluoroethylene films and the catalyst layer are all square in shape with a side length of 5cm*5cm.

[0078] S2: First, place the upper pressure block 2 into the upper pressure block positioning hole 5 in the pressure regulating knob boss 10. Then, place the second heating rod 305 and the second temperature sensor 303 into the lower heating rod hole 8 and the lower temperature sensor hole 7 in the sample boss 6, respectively. Place the first heating rod 304 and the first temperature sensor 302 into the upper heating rod hole 13 and the upper temperature sensor hole 12 in the upper pressure block 2, respectively. Electrically connect the two temperature sensors to the temperature digital display component 301, and adjust the sample boss 6 and the upper pressure block 2 to the desired position. The required temperature is maintained for 0.5 hours. After aligning the pressure sensor 402 and the thermal decay test sample of the catalyst layer 17, the sample boss 6 and the upper pressure block 2 are placed from bottom to top. The pressure sensor 402 is electrically connected to the pressure digital display component 401 to monitor the pressure on the sample under test. The pressure adjustment knob 3 is then screwed into the threaded hole 4 to adjust the pressure on the sample to the required pressure. The above device is then placed in the temperature and humidity chamber 1', and the ambient humidity is adjusted to the required humidity and maintained for 1 hour to complete the assembly of the offline loading device.

[0079] S3: Offline thermal decay durability experiments were conducted on the catalyst layer thermal decay test samples, and thermal decay durability experiments were carried out under different key parameters such as pressure, internal temperature, internal humidity and thermal decay durability time of the test samples. After the durability test, relevant characterization techniques, such as pore structure analysis, surface morphology analysis, component distribution analysis and electrical performance testing, were used to characterize the degree of thermal decay of the catalyst layer, and finally a database of catalyst layer thermal decay indexes was established to provide basic data for analyzing the thermal decay mechanism of the catalyst layer.

[0080] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. An offline loading device for studying the thermal degradation of a fuel cell catalyst layer, characterized in that, It includes a temperature and humidity chamber (1'), an offline loading fixture (2'), a temperature control assembly (3'), and a pressure control assembly (4'); The offline loading fixture (2') includes, from bottom to top, a fixture base (1), a pressure component and a pressure adjustment knob (3), which are used to clamp and fix the sample to be tested; The temperature control component (3') includes a heating element, a temperature sensor, and a temperature display element (301) for monitoring and visualizing the internal temperature of the sample to be tested. The temperature sensor and the temperature display element (301) are electrically connected. The pressure control component (4') includes a pressure sensor and a pressure digital display component (401) for monitoring and visualizing the pressure that the sample under test can withstand. The pressure digital display component (401) is electrically connected to the pressure sensor. The offline loading fixture (2'), the sample to be tested, the temperature control component (3'), and the pressure control component (4') are placed inside the temperature and humidity chamber (1'); The fixture base (1) includes a sample boss (6) and a pressure adjustment knob boss (10). The pressure adjustment knob boss (10) is provided with a threaded hole (4), which is used to install the pressure adjustment knob (3). The pressure regulating knob (3) includes a knob head (15) and a knob rod (16). The knob rod (16) is provided with an external thread (14), which matches the threaded hole (4). The pressure component is the upper pressure block (2); The heating component is a heating rod, and there are two heating rods and two temperature sensors. The upper pressure block (2) and the sample protrusion (6) are each provided with a heating rod and a temperature sensor. The sample boss (6) is a square boss, located at the center of the fixture base (1). The sample boss (6) has a lower temperature sensor hole (7) and a lower heating rod hole (8) on both sides. The lower temperature sensor hole (7) is used to install a second temperature sensor (303), which is used to detect the temperature of the lower surface of the sample to be tested. The lower heating rod hole (8) is used to install a second heating rod (305), which is used to heat the lower surface of the sample. The sample to be tested is placed on the sample boss (6). The sample to be tested has polytetrafluoroethylene films (18) on both sides and a catalyst layer (17) in the middle. The polytetrafluoroethylene films (18) and the catalyst layer (17) are both squares of the same size. The size of the sample to be tested is the same as the size of the sample boss (6).

2. The offline loading device for studying the thermal decay of a fuel cell catalyst layer according to claim 1, characterized in that, The pressure sensor is a thin-film pressure sensor (402), which is fixed on the sample boss (6).

3. The offline loading device for studying the thermal decay of a fuel cell catalyst layer according to claim 1, characterized in that, The upper pressure block (2) is a cuboid, and the upper pressure block (2) has an upper temperature sensor hole (12) and an upper heating rod hole (13) on both sides near the sample to be tested.

4. The offline loading device for studying the thermal decay of a fuel cell catalyst layer according to claim 3, characterized in that, The upper temperature sensor hole (12) is used to install the first temperature sensor (302), which is used to detect the temperature of the upper surface of the sample to be tested; the upper heating rod hole (13) is used to install the first heating rod (304), which is used to heat the upper surface of the sample to be tested.

5. The offline loading device for studying the thermal decay of a fuel cell catalyst layer according to claim 1, characterized in that, The pressure regulating knob boss (10) is located at the center of the fixture base (1). The side of the pressure regulating knob boss (10) is provided with rectangular through holes (9). The rectangular through holes (9) are used to reserve the clamping space of the sample to be tested and to achieve full contact between the sample to be tested and the external environment.

6. The offline loading device for studying the thermal degradation of a fuel cell catalyst layer according to claim 1, characterized in that, The pressure regulating knob boss (10) is also provided with an upper pressure block positioning hole (5), which is used to install the upper pressure block (2).

7. A method of using the offline loading device for studying the thermal degradation of a fuel cell catalyst layer according to any one of claims 1-6, characterized in that, Includes the following steps: S1: Samples for testing the thermal decay of the catalyst layer are prepared by spraying or blade transfer method; S2: First, assemble the offline loading fixture (2') and the temperature control component (3') and adjust the required temperature; then put in the pressure sensor and the sample to be tested prepared in S1, and then assemble the pressure control component (4') and adjust the required pressure; finally, put the assembled components into the temperature and humidity chamber (1'), adjust the ambient humidity, and complete the assembly of the offline loading device. S3: In the device assembled in S2, conduct an offline thermal decay durability experiment on the sample to be tested for thermal decay of the catalyst layer. Analyze the experimental results using relevant characterization techniques and establish a database of thermal decay indexes for the catalyst layer to provide basic data for elucidating the thermal decay mechanism of the catalyst layer.

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