A method for characterizing working conditions of a fuel cell membrane electrode interface by raman signals

Abstract

The application belongs to the technical field of spectral detection, and specifically discloses a kind of characterization methods of fuel cell membrane electrode interface working condition Raman signal, comprising the following steps: constructing fuel cell suitable for Raman test, preparing membrane electrode, assembling fuel cell, assembling in-situ Raman spectrum detection device, detecting fuel cell membrane electrode Raman signal.The application constructs fuel cell window piece, and makes laser passage by constructing window piece, optimizes flow field plate structure and material, avoids the problem that Raman laser cannot be focused due to too large distance from window piece to membrane electrode and the problem that operation platform is unstable due to too heavy weight of fuel cell, and can detect membrane electrode spectral information;The application can be applied to signal detection in different electrocatalytic reaction processes of membrane electrode cathode and anode, thereby providing guidance for the design of electrocatalyst.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of spectral detection, and particularly relates to a characterization method of fuel cell membrane electrode interface working condition Raman signal. BACKGROUND

[0002] The commercialization of fuel cells is still greatly limited due to high cost and low durability. The durability of fuel cells is reduced due to catalyst deactivation and electrolyte membrane aging, thereby causing problems such as performance reduction of fuel cells, electrolyte membrane aging, and the like. The corrosion of catalyst carriers and the poisoning of catalysts by CO are important reasons for the performance degradation of membrane electrodes. Carbon materials are the most widely used carrier materials in PEMFC catalysts due to their low cost and high electrical conductivity and chemical stability. The carbon carrier not only provides stable loading sites for catalyst nanoparticles, but also provides a way for electron and material transfer. However, the corrosion of carbon carriers in the catalyst layer will cause the collapse of catalyst anchoring sites, making catalyst nanoparticles separate, migrate, and agglomerate, and ultimately causing a serious reduction in the electrochemically active area and a significant reduction in performance. The formation of hydrophilic oxidation functional groups on the carbon surface reduces the hydrophobicity of the carbon surface, and the membrane electrode is more prone to water flooding. These factors will adversely affect the performance of the membrane electrode. In addition, up to 90% of H2 in the industry is obtained by reforming and purifying fossil fuels, and inevitably contains CO impurities. The strong adsorption of CO on the surface of transition metals causes serious poisoning problems in many catalytic processes.

[0003] Raman spectroscopy is a non-destructive and sensitive spectroscopic technique suitable for the study of interfaces. However, traditional in-situ and non-in-situ characterization cannot reproduce the complex interfacial environment of fuel cell membrane electrodes, and the results obtained may deviate from the true situation. Therefore, it is necessary to develop a new generation of working condition characterization technology to further reveal the reaction mechanism, guide the synthesis of high-performance and high-durability catalysts, and promote the development of fuel cells. SUMMARY

[0004] The purpose of the present application is to overcome the deficiencies in the prior art and provide a characterization method of fuel cell membrane electrode interface working condition Raman signal, which can observe the corrosion of carbon carriers and the adsorption of CO on Pt on the membrane electrode interface under working conditions.

[0005] In order to achieve the above purpose, the technical scheme of the present application is as follows: a characterization method of fuel cell membrane electrode interface working condition Raman signal, specifically comprising the following steps:

[0006] (1) Fuel cell design: a fuel cell suitable for Raman testing is constructed, and the fuel cell comprises a fastener, a window sheet, a cathode end plate, an anode end plate, a cathode flow field plate, an anode flow field plate, a cathode vent plate, an anode vent plate, and a membrane electrode.

[0007] (2) Preparation of membrane electrode: cut the gas diffusion layer and catalyst coated membrane into a suitable size for fuel cell, and open a small hole on the gas diffusion layer side which can pass through the Raman laser;

[0008] (3) Assembly of fuel cell: assemble the gas diffusion layer and catalyst coated membrane with small hole opened in step (2) in the fuel cell designed in step (1);

[0009] (4) Assembly of in-situ Raman spectrum detection device: convert the vertical laser of the confocal Raman instrument into horizontal laser, and the fuel cell also needs to be placed vertically, so that the surface of the membrane electrode and the direction of the laser remain perpendicular angle;

[0010] (5) Detection of Raman signal of fuel cell membrane electrode: pass the reaction gas into the anode and cathode of the fuel cell respectively, control the temperature of the fuel cell, and test the Raman signal of the fuel cell membrane electrode under the working condition.

[0011] In a preferred embodiment of the present application, the fuel cell in step (1) is made by constructing a window sheet, and the material of the window sheet is quartz, and the thickness of the window sheet is 0.2-5 mm.

[0012] In a preferred embodiment of the present application, the cathode flow field plate and the anode flow field plate in step (1) are made of graphite plate or metal plate, and the thickness of the graphite plate or metal plate is 0.2-8 mm.

[0013] In a preferred embodiment of the present application, the cathode flow field plate is provided with a cathode tab, and the anode flow field plate is provided with an anode tab, and both the cathode flow field plate and the anode flow field plate are provided with a hollow serpentine flow field and an auxiliary gas inlet channel.

[0014] Further preferably, the width of the flow channel groove is 0.1-5 mm, the depth of the flow channel groove is 0.1-5 mm, and the width of the ridge is 0.1-5 mm.

[0015] In a preferred embodiment of the present application, the cathode gas distribution plate in step (1) is provided with gas inlet and outlet holes and a region for placing the window sheet, and the anode gas distribution plate is provided with gas inlet and outlet holes and a region for placing the heating sheet.

[0016] In a preferred embodiment of the present application, the material of the cathode end plate and the anode end plate in step (1) is metal or PEEK, and the central region of the cathode end plate and the anode end plate is hollowed out to reduce the overall weight of the fuel cell.

[0017] In a preferred embodiment of the present application, the area of the gas diffusion layer and the catalyst coated membrane in step (2) is 0.5-25 cm 2 , and the diameter of the opening is 50-2000 μm.

[0018] In a preferred embodiment of the present application, the assembling step in step (3) specifically comprises placing the anode end plate, the anode gas diffusion plate and the anode flow field plate in sequence on the table top; placing the corresponding anode side sealing gasket; placing the anode gas diffusion layer according to the gasket positioning; placing the catalyst coated membrane; placing the cathode gas diffusion layer; placing the corresponding cathode side sealing gasket; placing the cathode flow field plate, the cathode gas diffusion plate and the cathode end plate; fastening the fuel cell using the screw rod and the nut, and completing the single cell assembly.

[0019] In a preferred embodiment of the present application, the battery temperature in step (5) is controlled at room temperature to 200°C.

[0020] In a preferred embodiment of the present application, the fuel cell test in step (5) can use normal discharge interval or accelerated test, including but not limited to triangular wave potential cycle, square wave potential cycle and constant potential test.

[0021] Compared with the prior art, the present application has the following beneficial effects:

[0022] 1. The present application can detect the membrane electrode spectral information by constructing the fuel cell window sheet, and by constructing the window sheet to make the laser path, optimizing the flow field plate structure and material, avoiding the problem that the Raman laser cannot be focused due to the excessive distance from the window sheet to the membrane electrode, and the problem that the operation platform is unstable due to the excessive weight of the fuel cell.

[0023] 2. The present application can be applied to signal detection in the different electrocatalytic reaction processes of the membrane electrode anode and cathode, thereby providing guidance for the design of electrocatalysts. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 The present application is a fuel cell model designed in Example 1,

[0025] Wherein: 1-fastener, 2-window sheet screw cap, 3-quartz window sheet, 4-cathode end plate, 5-cathode gas diffusion plate, 6-cathode flow field plate, 7-membrane electrode, 8-anode flow field plate, 9-anode gas diffusion plate, 10-anode end plate;

[0026] Figure 2 The present application is the polarization curve and power density curve of the fuel cell obtained in Example 1,

[0027] Figure 3 The present application is the Raman spectrum of the carbon carrier corrosion under the working condition obtained in Example 2,

[0028] Figure 4 The present application is the Raman spectrum of CO adsorption on Pt catalyst under the working condition in Example 3. DETAILED DESCRIPTION

[0029] In order to make the objects, technical solutions and advantages of the present application clearer, the present application will be described in more detail below with reference to the drawings and specific embodiments, but the protection scope of the present application is not limited to these embodiments.

[0030] A characterization method of fuel cell membrane electrode interface working condition Raman signal, specifically comprising the following steps:

[0031] (1) Fuel cell design: construct a fuel cell suitable for Raman testing, key components include fasteners, window sheets, cathode end plates, anode end plates, cathode flow field plates, anode flow field plates, cathode ventilation plates, anode ventilation plates, membrane electrodes;

[0032] (2) Preparation of membrane electrode: cut the gas diffusion layer and catalyst coated membrane into a size suitable for a fuel cell, with an area size of 0.5-25 cm 2 , and a small hole is opened on the gas diffusion layer side;

[0033] (3) Assemble the fuel cell: assemble the gas diffusion layer with a small hole and the catalyst coated membrane in the fuel cell designed in step (1) according to the assembly sequence, and fasten with bolts;

[0034] (4) Assemble in-situ Raman spectrum detection device: convert the vertical laser of the confocal Raman instrument into a horizontal laser, and the fuel cell also needs to be placed vertically, so that the membrane electrode surface and the laser direction maintain a vertical angle;

[0035] (5) Detect the Raman signal of the fuel cell membrane electrode: introduce the reaction gas into the anode and cathode of the fuel cell respectively, control the temperature of the fuel cell, and test the Raman signal of the fuel cell membrane electrode under working condition.

[0036] The fuel cell in step (1) realizes the passage of laser to the membrane electrode by constructing a window sheet, and the material of the window sheet is quartz, and the thickness of the window sheet is 0.2-5 mm.

[0037] The cathode flow field plate and the anode flow field plate in step (1) are made of graphite plate or metal plate, and the thickness of the graphite plate or metal plate is 0.2-8 mm.

[0038] The cathode flow field plate in step (1) is provided with a cathode tab, and the anode flow field plate is provided with an anode tab, and the cathode flow field plate and the anode flow field plate are both provided with a hollow serpentine flow field and an auxiliary gas inlet channel without hollowing.

[0039] The flow channel groove width in step (1) is 0.1-5 mm, the groove depth is 0.1-5 mm, and the ridge width is 0.1-5 mm.

[0040] The cathode ventilation plate in step (1) is provided with gas inlet and outlet holes and a window sheet placement area, and the anode ventilation plate is provided with gas inlet and outlet holes and a heating sheet placement area.

[0041] The cathode end plate and the anode end plate in step (1) are made of metal or PEEK, and the central area of the cathode end plate and the anode end plate is hollowed out to reduce the overall weight of the fuel cell.

[0042] In step (2), a small hole with a diameter of 50-2000 μm is opened in one side of the gas diffusion layer.

[0043] In step (3), the assembly steps are as follows: placing the anode end plate, the anode ventilation plate and the anode flow field plate on a table in sequence; placing the corresponding anode side gasket; placing the anode gas diffusion layer according to the gasket positioning; placing the catalyst coated film; placing the cathode gas diffusion layer; placing the corresponding cathode side gasket; placing the cathode flow field plate, the cathode ventilation plate and the cathode end plate; and fastening the fuel cell using a screw and a nut to complete the assembly of the single cell.

[0044] In step (5), the test temperature of the fuel cell is controlled at room temperature-200°C.

[0045] In step (5), the fuel cell test can use normal discharge interval or accelerated test, and the test methods include but are not limited to triangular wave potential cycling, square wave potential cycling and constant potential test.

[0046] Example 1

[0047] The polarization curve and power density curve of the fuel cell are tested according to the following specific method:

[0048] (1) Design a fuel cell for Raman test, as shown in Figure 1 and make each component; wherein the laser path of the fuel cell is made through a quartz window sheet with a thickness of 1 mm, and the cathode flow field plate and the anode flow field plate are made of graphite plates with a thickness of 3 mm; the cathode flow field plate is provided with a cathode tab, the anode flow field plate is provided with an anode tab, and the cathode flow field plate and the anode flow field plate are both provided with a hollowed-out serpentine flow field and an un-hollowed auxiliary gas inlet channel; the width of the flow channel groove is 1 mm, the depth of the flow channel groove is 3 mm, and the width of the ridge is 1 mm; the lower ventilation plate is provided with gas inlet and outlet holes and a window sheet and heating sheet placement area; the cathode end plate and the anode end plate are made of PEEK material, and the central area of the cathode end plate and the anode end plate is hollowed out.

[0049] (2) Prepare a membrane electrode: cut the gas diffusion layer and the catalyst coated film into appropriate sizes with an area of 3 cm 2 and open a small hole with a diameter of 500 μm in one side of the gas diffusion layer so that the Raman laser can be focused on the catalyst surface.

[0050] (3) Assemble the fuel cell: place the anode end plate, anode gas diffusion plate and anode flow field plate in sequence on the table; place the corresponding anode-side sealing gasket; place the anode gas diffusion layer according to the gasket positioning; place the catalyst-coated film; place the cathode gas diffusion layer; place the corresponding cathode-side sealing gasket; place the cathode flow field plate, cathode gas diffusion plate and cathode end plate; fasten the fuel cell using the screw and nut, and complete the single cell assembly.

[0051] (4) Perform electrochemical test: introduce O2 and H2 into the anode and cathode respectively, control the fuel cell reaction temperature to be 80°C, perform electrochemical test on the fuel cell test device using the constant current density test method, and obtain the polarization curve and power density curve test results of the fuel cell.

[0052] This example uses a commercial membrane electrode, and the fuel cell voltage is tested at 0-2 A / cm 2 , and the power density curve is obtained. The open circuit voltage of the fuel cell is 0.96 V, and the power density can reach 0.73 W / cm 2 at 1.4 A / cm 2 . The electrochemical characterization basically reaches the commercial fuel cell test standard.

[0053] Example 2

[0054] The working condition Raman spectrum test of fuel cell carbon carrier corrosion is as follows:

[0055] Assemble the fuel cell according to the method of Example 1, then convert the vertical laser of the confocal Raman instrument into a horizontal laser through a light path conversion lens, place the electrolytic cell vertically, and make the membrane electrode surface and the laser direction keep a vertical angle. After the in-situ Raman spectrum detection device is assembled by the above method, N2 and H2 are introduced into the cathode and anode respectively, the fuel cell reaction temperature is controlled to be 80°C, and the cathode potential is controlled to be 1-1.5 V (vs. RHE) to detect the carbon carrier corrosion of the cathode catalyst layer, as shown in Figure 3 , the two curves are respectively the Raman spectrum peaks of the cathode catalyst before and after the test.

[0056] This example is a high specific surface area carbon carrier. During the carbon corrosion process, the oxidation speed of the disordered structure in the carbon carrier is higher than that of the ordered structure, that is, the disordered structure is preferentially oxidized in the carbon corrosion, and carbon oxygen species appear on the surface. With the progress of carbon corrosion, the average graphite grain presents a trend of becoming larger.

[0057] Example 3

[0058] The working condition Raman spectrum test of fuel cell carbon monoxide poisoning is as follows:

[0059] The fuel cell was assembled according to the method of Example 1, and then the vertical laser of the confocal Raman instrument was converted to horizontal laser by a light path conversion lens. The electrolytic cell was placed vertically, so that the membrane electrode surface and the laser direction kept a vertical angle. After the in-situ Raman spectrum detection device was assembled by the above method, O2 and mixed gas (50 ppm CO + H2) were introduced into the anode and cathode respectively, the reaction temperature of the fuel cell was controlled at 80°C, the Au@Pt core-shell structure nanoparticles were constructed on the anode catalyst layer, the discharge current density was controlled at 1 A / cm 2 , and the adsorption of CO on Pt was detected.

[0060] The commercial membrane electrode was used in this example, as shown in Figure 4 , with the introduction of CO, new peaks appeared at 483 cm -1 and 2053 cm -1 . The peak at 483 cm -1 may be referred to as the Pt-C stretching vibration of the adsorbed CO on Pt, and the peak at 2053 cm -1 may be referred to as the C-O stretching vibration peak of the adsorbed CO on Pt.

[0061] The above examples are only optimized implementation methods of the present application, which are used to illustrate the principles and effects of the present application, and are not used to limit the present application. It should be noted that any person skilled in the art can modify the above examples without departing from the spirit and scope of the present application, and these modifications should also be considered as the protection scope of the present application.

Claims

1. A method for characterizing the Raman signal at the membrane electrode interface of a fuel cell under operating conditions, characterized in that, Includes the following steps: (1) Fuel cell design: Construct a fuel cell suitable for Raman testing, the fuel cell including fasteners, windows, cathode end plate, anode end plate, cathode flow field plate, anode flow field plate, cathode venting plate, anode venting plate, and membrane electrode assembly; (2) Preparation of membrane electrode: The gas diffusion layer and the catalyst coating membrane are cut to a size suitable for fuel cells, and small holes are made on one side of the gas diffusion layer; (3) Assemble the fuel cell: Assemble the gas diffusion layer with small holes in step (2) and the catalyst coating film in the fuel cell designed in step (1), and fasten them with bolts; (4) Assemble the in-situ Raman spectroscopy detection device: convert the vertical laser of the confocal Raman instrument into a horizontal laser. The fuel cell also needs to be placed vertically so that the surface of the membrane electrode and the laser direction are perpendicular to each other. (5) Detecting the Raman signal of the membrane electrode of the fuel cell: The reaction gas is introduced into the anode and cathode of the fuel cell respectively, the temperature of the fuel cell is controlled, and the Raman signal of the membrane electrode of the fuel cell is tested under the operating conditions. The fuel cell is constructed by creating a laser path through a window, the window being made of quartz and having a thickness of 0.2–5 mm. The cathode flow field plate and anode flow field plate are made of graphite plates, the graphite plates having a thickness of 0.2–8 mm. Both the cathode flow field plate and the anode flow field plate are provided with a hollowed-out serpentine flow field and a non-hollowed-out auxiliary air intake channel; The serpentine flow field channel has a groove width of 0.1–5 mm, a groove depth of 0.1–5 mm, and a ridge width of 0.1–5 mm. The cathode vent plate forms an area for air inlet and outlet and for placing window plates, while the anode vent plate forms an area for air inlet and outlet and for placing heating elements. The area of ​​the gas diffusion layer and the catalyst coating film is 0.5–25 cm². 2 The aperture diameter is 50–2000 μm; The assembly steps in step (3) are as follows: placing the anode end plate, anode vent plate and anode flow field plate in sequence; placing the corresponding sealing gaskets on the anode side; placing the anode gas diffusion layer according to the gasket positioning; and placing the catalyst coating film. Place the cathode gas diffusion layer; place the corresponding cathode-side sealing gaskets; place the cathode flow field plate, cathode vent plate, and cathode end plate; use screws and nuts to fasten the fuel cell to complete the single cell assembly; The fuel cell testing temperature was controlled between room temperature and 200°C. The fuel cell test adopts the normal discharge range or accelerated test, and the test methods include, but are not limited to, triangular wave potential cycle, square wave potential cycle and constant potential test.

2. The method for characterizing the Raman signal at the membrane electrode interface as described in claim 1, characterized in that, In step (1), the cathode flow field plate is provided with cathode tabs, and the anode flow field plate is provided with anode tabs.

3. The method for characterizing the Raman signal at the membrane electrode interface as described in claim 1, characterized in that, In step (1), the material of the negative end plate and the positive end plate is metal or PEEK, and the central area of ​​the negative end plate and the positive end plate needs to be hollowed out.

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