Degradation acceleration method using PEM electrolytic cell membrane electrode degradation acceleration system, in-situ detection system and in-situ detection method

Abstract

The invention relates to an accelerated degradation method, an in-situ detection system and an in-situ detection method by using a PEM electrolytic cell membrane electrode accelerated degradation system. The PEM electrolytic bath membrane electrode degradation acceleration system comprises a miniature PEM electrolytic bath, a current degradation module, a deionized water circulation module and a temperature control module, the in-situ detection system comprises a micro PEM electrolytic cell, an XCT module and an electrochemical characterization module. Through the micro PEM electrolytic cell, the membrane electrode can be subjected to in-situ microscopic characterization by using a laboratory XCT system after accelerated degradation, so that the defects that an existing PEM electrolytic cell is large in size and cannot be subjected to high-resolution shooting in a commercial micro XCT machine, and an existing PEM electrolytic cell membrane electrode degradation visual detection technology is not in situ and cannot be repeated are overcome; and in-situ, non-destructive and high-resolution three-dimensional detection of the PEM electrolytic cell membrane electrode is realized.

Description

Technical Field

[0001] The present invention relates to the technical field of in-situ detection of membrane electrodes in PEM electrolyzers, and in particular to an accelerated degradation method utilizing a PEM electrolyzer membrane electrode accelerated degradation system, an in-situ detection system and an in-situ detection method. Background Art

[0002] The accelerated consumption of fossil fuels and their high carbon dioxide emissions have prompted people to look for alternative fuels. Renewable energy is considered a promising alternative to fossil fuels. Hydrogen, a product of water electrolysis coupled with renewable energy, is a flexible and clean energy carrier that can store a large amount of energy and can be efficiently converted back into electricity through fuel cells. Among all types of electrolyzers, PEM electrolyzers have higher current density, lower gas permeability, smaller mass-volume characteristics, higher gas purity, and higher safety, providing the most ideal prospect for hydrogen production. And because of its fast dynamic response time, it can be stably coupled with renewable energy. However, to this day, electrolyzers still have the problem of high component cost, and performance and durability need to be improved. As the core component of PEM electrolyzers, proton exchange membranes provide a transmission channel that only allows water molecules and hydronium ions to pass through, transporting protons from the anode of the electrolyzer to the cathode of the electrolyzer, and forming an ion transfer path inside the electrolyzer. The performance degradation of the proton exchange membrane of the PEM electrolyzer is mainly attributed to chemical degradation caused by the load current. Chemical degradation forms hydrogen peroxide or free radicals on the catalyst. The proton exchange membrane is attacked by free radicals to produce a "decompression reaction" that thins the membrane, exacerbates the crossover of product gases, and further accelerates the generation of free radicals, resulting in a significant shortening of the proton exchange membrane life. In addition, the proton exchange membrane will be more easily punctured, torn, and cracked. The thinning of the proton exchange membrane and the generation of defects will cause serious degradation of the electrolyzer performance and pose a great safety hazard. Mechanical property tests such as tensile strength, elongation at break, Young's modulus, and dimensional change rate are commonly used for performance testing of PEM electrolyzer proton exchange membranes, but these methods are not designed for chemical durability testing. Therefore, it is urgent to design a chemical accelerated degradation system to provide a more realistic accelerated degradation environment for the proton exchange membrane that is more suitable for the operating conditions of the PEM electrolyzer, and to perform electrochemical performance testing and visual defect detection on the PEM electrolyzer membrane electrode that has undergone this chemical accelerated degradation.

[0003] Scanning electron microscopy (SEM) is often used for high-resolution microscopic characterization of PEM electrolyzer membrane electrodes, but it is also limited by the following aspects: SEM imaging is mainly concentrated on the surface of the sample, and it is difficult to obtain information on the internal structure; the SEM sample preparation process requires cutting, polishing and coating, which may cause damage or contamination to the sample, affecting the imaging quality and the accuracy of the research results; SEM needs to be carried out in a vacuum environment, and the PEM electrolyzer membrane electrodes may change under vacuum conditions, affecting the observation of their original state; SEM usually images samples under static conditions, making it difficult to achieve in-situ observation of the PEM electrolyzer membrane electrodes under actual working conditions. The above shortcomings limit the application of SEM in the comprehensive study of the microstructure and performance of PEM electrolyzer membrane electrodes.

[0004] X-ray computed tomography (XCT) technology uses X-rays to penetrate objects and receive the transmitted X-rays through detectors to obtain multi-angle projection data of the object. Through computer algorithms, the projection data is reconstructed into a three-dimensional image of the interior of the object, thereby providing detailed information on the internal structure of the object. XCT can perform imaging under actual working conditions, allowing researchers to observe the microstructural changes of the membrane electrode in real time during the operation of the electrolyzer; XCT is a non-destructive detection technology that does not require physical destruction or cutting of the sample. XCT can provide detailed information on the interior of the sample. The same sample can be scanned and monitored multiple times for changes at different time points or operating conditions without causing damage to the sample; XCT can provide high-resolution three-dimensional images, allowing researchers to observe the microstructure inside the membrane electrode in detail, including pores, cracks, catalyst particle distribution, etc., which helps to understand the relationship between its microstructure and macroscopic performance; these advantages enable XCT to provide comprehensive, accurate and detailed PEM electrolyzer membrane electrode structure and performance information, which helps to deeply study its working mechanism and degradation process and promote the development and optimization of PEM electrolyzer technology.

[0005] At present, there is no definite and unified method for evaluating the durability of PEM electrolyzer membrane electrodes. The common practice in the PEM electrolyzer industry is to measure the membrane electrode life under stable operating conditions (constant current mode) and variable operating conditions (variable operating cycle). The commonly used method for evaluating the durability of cell membrane electrodes in the fuel cell industry is accelerated stress cycle testing. The above-mentioned related applications provide ideas for the method of accelerated chemical degradation testing of PEM electrolyzer membrane electrodes, using a high-frequency current density cycle to accelerate the chemical degradation of PEM electrolyzer membrane electrodes.

[0006] The existing technology mainly focuses on the cost reduction and efficiency improvement research of the key components of the PEM electrolyzer and the PEM electrolyzer stack, but there are few studies on the formation and development process of chemical degradation of the membrane electrode of the PEM electrolyzer, and the full three-dimensional internal structure, non-destructive detection, in-situ imaging, material contrast and element distribution analysis, and quantitative analysis methods of the membrane electrode of the PEM electrolyzer are not perfect. In order to be able to more comprehensively and accurately understand the microstructure and dynamic changes of the membrane electrode of the PEM electrolyzer after accelerated chemical degradation, XCT in-situ detection is introduced and used. The present invention designs a micro PEM electrolyzer and a corresponding PEM electrolyzer membrane electrode accelerated degradation system, and designs an in-situ detection system of the PEM electrolyzer membrane electrode accelerated degradation system including an XCT module and an electrochemical characterization module to realize in-situ and non-destructive detection of the membrane electrode of the PEM electrolyzer.

[0007] Carrying out accelerated chemical degradation experiments on PEM electrolyzers can not only deeply explore the degradation mechanism and provide a scientific basis for the optimization of membrane electrode materials and processes, but also improve the performance and life of the electrolyzer, reduce costs, promote the formulation of industry technical standards, support theoretical model verification, accelerate the R&D cycle, and enhance product competitiveness, so as to promote the advancement and application of PEM electrolyzer technology. Summary of the invention

[0008] The purpose of the present invention is to overcome the shortcomings of the prior art and provide an accelerated degradation method, an in-situ detection system and an in-situ detection method using a PEM electrolyzer membrane electrode accelerated degradation system. Through a micro PEM electrolyzer, the membrane electrode can be subjected to in-situ microscopic characterization using a laboratory XCT system after undergoing accelerated degradation. The shortcomings of the existing PEM electrolyzer, which is large in size and cannot be photographed at high resolution on a commercial micro XCT machine, and the existing PEM electrolyzer membrane electrode degradation visualization detection technology is non-in-situ and non-repeatable, are overcome, thereby achieving in-situ, non-destructive, high-resolution three-dimensional detection of the PEM electrolyzer membrane electrode.

[0009] The present invention solves the technical problem by the following technical solutions:

[0010] A PEM electrolyzer membrane electrode accelerated degradation system comprises a micro PEM electrolyzer, a current degradation module, a deionized water circulation module and a temperature control module; the current degradation module, the deionized water circulation module and the temperature control module are respectively connected to the PEM electrolyzer;

[0011] The current degradation module includes a programmable DC power supply and a banana plug to flat port test lead; the programmable DC power supply is connected to the micro PEM electrolyzer through the banana plug to flat port test lead;

[0012] The deionized water circulation module comprises a deionized water tank, a digital display peristaltic pump, a PVC hose, a reducer straight-through joint and a quick-insert straight-through joint; the micro PEM electrolyzer is connected to one end of the quick-insert straight-through joint through threaded cooperation, and the other end of the quick-insert straight-through joint is connected to a three-way joint through a PVC hose, and the deionized water tank and the digital display peristaltic pump are connected through the PVC hose to form a water circulation;

[0013] The temperature control module includes a switching power supply, a digital display intelligent temperature controller, a solid-state relay, a platinum resistor and high-temperature ceramic heating plates respectively attached to the left and right sides of the I-shaped structure of the micro PEM electrolytic cell; the digital display intelligent temperature controller and the platinum resistor are connected to form a temperature sensing circuit, and the switching power supply, the digital display intelligent temperature controller, the solid-state relay and the high-temperature ceramic heating plate are connected to form a heating circuit.

[0014] Furthermore, the micro PEM electrolyzer comprises an anode terminal plate, an anode PVC gasket, an anode flow field plate, an anode polytetrafluoroethylene gasket, an anode porous transport layer, a proton exchange membrane coated with a catalyst layer, a cathode porous transport layer, a cathode polytetrafluoroethylene gasket, a cathode flow field plate, a cathode PVC gasket and a cathode terminal plate, wherein the anode terminal plate, the anode PVC gasket, the anode flow field plate, the anode polytetrafluoroethylene gasket, the cathode polytetrafluoroethylene gasket, the cathode flow field plate, the cathode PVC gasket and the cathode terminal plate are all tapped with threaded holes at the same position, and the anode terminal plate, the anode PVC gasket, the anode flow field plate, the anode polytetrafluoroethylene gasket, the anode porous transport layer, the proton exchange membrane coated with a catalyst layer, the cathode porous transport layer, the cathode polytetrafluoroethylene gasket, the cathode flow field plate, the cathode PVC gasket and the cathode terminal plate are stacked up in sequence, positioned by bolts, and sealed and fastened in cooperation with nuts; the anode PVC gasket, the anode flow field plate, the cathode flow field plate and the cathode The PVC gaskets are provided with circular through holes one and two which are symmetrical up and down as upper gas-liquid inlet and outlet and lower gas-liquid inlet and outlet to transmit water and gas; the anode flow field plate and the cathode flow field plate are provided with two parallel square grooves from the upper gas-liquid inlet and outlet to the lower gas-liquid inlet and outlet on the side of the proton exchange membrane coated with the catalyst layer as gas and liquid flow channels, and a raised flow channel ridge is naturally formed in the middle of the two square grooves; the anode end plate, the anode PVC gasket, the anode flow field plate, the anode polytetrafluoroethylene gasket, the cathode polytetrafluoroethylene gasket, the cathode flow field plate, the cathode PVC gasket and the cathode end plate are all made into an I-shaped structure with the same width at the top and the bottom and a narrower middle; the upper ends of the anode flow field plate and the cathode flow field plate are extended with rectangular electrodes; the anode end plate and the cathode end plate extend outwardly with their backs facing the proton exchange membrane coated with the catalyst layer to form an upper boss and a lower boss, and tap the internal threaded hole; the anode polytetrafluoroethylene gasket and the cathode polytetrafluoroethylene gasket are provided with rectangular through holes in the middle;

[0015] The programmable DC power supply is connected to the anode flow field plate and the rectangular electrode extending from the upper end of the cathode flow field plate of the micro PEM electrolyzer through a banana plug to a flat test lead;

[0016] The upper boss and the lower boss of the anode terminal plate and the lower boss and the cathode terminal plate boss and the lower boss of the micro PEM electrolyzer are respectively connected to one end of the quick-insert straight-through connector through threaded engagement.

[0017] A method for accelerating degradation of a PEM electrolyzer membrane electrode accelerated degradation system comprises the following steps:

[0018] S1: Run the deionized water circulation module: Make the deionized water flow rate into the PEM electrolyzer membrane electrode reach 1ml / min, and make the PEM electrolyzer membrane electrode fully wetted. The specific steps are as follows:

[0019] S1.1: Inject 50 ml of deionized water into the deionized water tank;

[0020] S1.2: Connect the power supply of the digital display peristaltic pump and turn on the switch of the digital display peristaltic pump;

[0021] S1.3: Adjust the set water delivery flow rate of the digital peristaltic pump to 1ml / min, and wait for the actual flow rate to stabilize at 1ml / min before proceeding to the next step;

[0022] S2: Run the temperature control module to keep the PEM electrolyzer membrane electrode in a constant temperature environment of 90°C. The specific steps are as follows:

[0023] S2.1: Connect the power supply of the digital display intelligent temperature controller and turn on the switch of the digital display intelligent temperature controller;

[0024] S2.2: Adjust the set temperature of the digital display intelligent temperature controller to 90℃, and wait for the actual temperature to stabilize at 90℃ before proceeding to the next step;

[0025] S3: Run the current degradation module to apply current circulation to the PEM electrolyzer membrane electrode. The specific steps are as follows:

[0026] S3.1: Connect the programmable DC power supply and turn on the programmable DC power supply switch;

[0027] S3.2: Connect the programmable DC power supply to the microcomputer via a USB communication cable;

[0028] S3.3: Adjust the programmable DC power supply output to a constant current cycle of 4A / 15s and 0A / 15s in the microcomputer program;

[0029] The effective area of ​​the membrane electrode of the PEM electrolyzer is 0.4*1.0mm. According to the current density calculation formula:

[0030] J=I / A

[0031] Where I is the current, A is the effective area of ​​the PEM electrolyzer membrane electrode;

[0032] The current density applied to the PEM electrolyzer membrane electrode is 10A / cm 2 / 15s, 0A / cm 2 / 15s;

[0033] S4: The PEM electrolyzer membrane electrode completes 500 current density cycles, and the current degradation module, the deionized water circulation module, and the temperature control module are turned off in sequence to cool the PEM electrolyzer membrane electrode to room temperature.

[0034] An in-situ detection method of an in-situ detection system using an accelerated degradation method of a PEM electrolyzer membrane electrode accelerated degradation system,

[0035] The in-situ detection system includes a micro PEM electrolyzer, an XCT module, and an electrochemical characterization module; the XCT module includes an X-ray source and an X-ray signal receiver located on the left and right sides of the imaging area; the electrochemical characterization module includes an electrochemical workstation;

[0036] The in-situ detection method includes the following steps:

[0037] S1: When the PEM electrolyzer membrane electrode is in the initial state and every time 500 current density cycles are completed, the PEM electrolyzer membrane electrode accelerated degradation system is turned off, and the PEM electrolyzer membrane electrode accelerated degradation system is cooled to room temperature, and the micro PEM electrolyzer is removed from the PEM electrolyzer membrane electrode accelerated degradation system;

[0038] S2: Start the XCT module and use a commercial micro XCT machine to take in-situ images of the PEM electrolyzer membrane electrode that has undergone current density cycling. Set the distance between the imaging area and the X-ray source to 13 mm, the distance between the imaging area and the X-ray signal receiver to 758 mm, set the acceleration voltage to 100 kV and the power to 12 W. After the image is taken, use the matching image reconstruction software to obtain a three-dimensional image of the PEM electrolyzer membrane electrode with a resolution of 1.7 μm.

[0039] S3: Start the electrochemical characterization module, turn on the electrochemical workstation, adjust the working mode of the electrochemical workstation to polarization curve test and electrochemical impedance spectroscopy test in sequence, and perform in-situ electrochemical performance test on the PEM electrolyzer membrane electrode that has undergone current density cycling;

[0040] S4: Repeat S1, S2, and S3 until the three-dimensional image of the membrane electrode of the PEM electrolyzer shows that the membrane crack area accounts for 15% of the failure condition or the membrane thickness is reduced by 15%, or the voltage decay rate reaches 15%, and the membrane electrode is judged to be failed and the test is terminated;

[0041] S5: Based on the XCT three-dimensional images, polarization curves, and electrochemical impedance spectroscopy of the above-mentioned cycle stages, an in-situ comparative analysis of the degradation of the PEM electrolyzer membrane electrode was performed.

[0042] The advantages and positive effects of the present invention are:

[0043] 1. The PEM electrolyzer membrane electrode accelerated degradation system of the present invention restores the actual production application PEM electrolyzer components and structures, creates a real PEM electrolyzer production condition environment, and adopts high-frequency current density circulation to accelerate the chemical degradation of the PEM electrolyzer membrane electrode; the PEM electrolyzer membrane electrode in-situ detection system composed of a micro PEM electrolyzer, an XCT module, and an electrochemical characterization module innovatively applies XCT technology to the field of PEM electrolyzer membrane electrode detection, and effectively makes up for the shortcomings of existing microscopic detection technologies such as SEM and TEM that are incomplete, non-in-situ, and non-repeatable by providing the full three-dimensional internal structure of the PEM electrolyzer, non-destructive detection, in-situ imaging, and quantitative analysis. Combined with electrochemical characterization, it can analyze in detail the interactions and microstructural changes of key components such as catalyst layers, membranes, and porous transport layers during operation, which is helpful to understand the degradation mechanisms such as chemical degradation of membranes and deactivation of catalysts.

[0044] 2. The PEM electrolyzer membrane electrode accelerated degradation system of the present invention innovatively reduces the design of the micro PEM electrolyzer, and its size is much smaller than the common PEM electrolyzer size on the market, so as to adapt to the high-resolution in-situ detection of commercial micro XCT and the focused observation of the vulnerable areas of the membrane electrode. Compared with the X-rays excited by the synchrotron radiation light source, the commercial micro XCT has the characteristics of moderate energy control, low radiation dose, small sample damage, and low thermal effect. It can maintain the original properties of the PEM electrolyzer after multiple XCT imaging, and has the advantages of simple operation, rapid imaging, and easy maintenance.

[0045] 3. The current degradation module of the PEM electrolyzer membrane electrode accelerated degradation system of the present invention can be used according to the PEM electrolyzer membrane electrode chemical degradation test method at 0A / cm 2 -10A / cm 2 High-frequency DC square wave circulation can be achieved within the range, and the programmable DC power supply can be connected to a microcomputer via a USB communication cable, and the PEM electrolyzer current circulation coupled with clean energy such as wind, light, and electricity can be edited and output. Compared with the ordinary current density cycle application method, the current degradation module of the PEM electrolyzer membrane electrode accelerated degradation system can simulate the dynamic behavior of the electrolyzer under actual operating conditions, greatly reducing the test time, and can simulate the intermittent and fluctuating output of wind and solar energy, providing a more realistic accelerated degradation environment.

[0046] 4. The present invention innovatively applies micro PEM electrolyzer and XCT technology to the field of PEM electrolyzer membrane electrode degradation detection. Aiming at the shortcomings of existing PEM electrolyzer membrane electrode degradation methods, such as long time consumption and poor coupling with the real degradation environment, a PEM electrolyzer membrane electrode accelerated degradation system is invented in combination with the characteristics of the micro design of the PEM electrolyzer, which significantly improves the degree of reduction of the real PEM electrolyzer chemical degradation environment. By utilizing the in-situ detection system of the PEM electrolyzer membrane electrode accelerated degradation system, non-destructive in-situ detection of PEM electrolyzer membrane electrode degradation is achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 A schematic diagram of a PEM electrolyzer membrane electrode accelerated degradation system of the present invention;

[0048] Figure 2 This is a partial enlarged view of the PEM electrolyzer membrane electrode accelerated degradation system of the present invention;

[0049] Figure 3 It is a structural schematic diagram of a micro PEM electrolyzer of the PEM electrolyzer membrane electrode accelerated degradation system of the present invention;

[0050] Figure 4 It is a schematic diagram of the in-situ detection system of the membrane electrode of the PEM electrolyzer of the present invention.

[0051] In the figure:

[0052] 1-nut, 2-cathode end plate, 3-circular through hole, 4-cathode PVC gasket, 5-cathode flow field plate, 6-cathode polytetrafluoroethylene gasket, 7-cathode porous transport layer, 8-proton exchange membrane coated with catalyst layer, 9-anode porous transport layer, 10-anode polytetrafluoroethylene gasket, 11-anode flow field plate, 12-anode PVC gasket, 13-anode end plate, 14-upper boss, 15-bolt, 16-lower boss, 17-M1.2 internal threaded hole, 18-I-shaped groove, 19-rectangular through hole, 20-membrane electrode positioning groove, 2 1-flow channel, 22-round through hole 2, 23-programmable DC power supply, 24-micro PEM electrolyzer, 25-high temperature ceramic heating plate, 26-platinum resistor, 27-digital display peristaltic pump, 28-deionized water tank, 29-digital display intelligent temperature controller, 30-solid state relay, 31-switching power supply, 32-banana plug to flat test lead, 33-PVC hose, 34-reducing straight-through connector, 35-quick plug straight-through connector, 36-three-way connector, 37-X-ray source, 38-X-ray signal receiver, 39-electrochemical workstation. DETAILED DESCRIPTION

[0053] The present invention is further described in detail below through specific examples. The following examples are only illustrative and not restrictive, and the protection scope of the present invention cannot be limited thereto.

[0054] like Figure 1-Figure 4 As shown, a PEM electrolyzer membrane electrode accelerated degradation system includes a micro PEM electrolyzer 24, a current degradation module, a deionized water circulation module and a temperature control module; the current degradation module, the deionized water circulation module and the temperature control module are respectively connected to the PEM electrolyzer; the miniaturized micro PEM electrolyzer is 30 mm high, 12 mm wide and 8 mm thick; the imaging area is a rectangle with a length of 8 mm and a width of 6 mm.

[0055] A micro PEM electrolyzer 24, comprising an anode terminal plate 13, an anode PVC gasket 12, an anode flow field plate 11, an anode polytetrafluoroethylene gasket 10, an anode porous transport layer 9, a proton exchange membrane 8 coated with a catalyst layer, a cathode porous transport layer 7, a cathode polytetrafluoroethylene gasket 6, a cathode flow field plate 5, a cathode PVC gasket 4 and a cathode terminal plate 2, an anode terminal plate 13, an anode PVC gasket 12, an anode flow field plate 11, an anode polytetrafluoroethylene gasket 10, a cathode polytetrafluoroethylene gasket 6, a cathode flow field plate 5, a cathode PVC gasket 4 and a cathode terminal plate 2 Tap M1.2 internal threaded holes 17 at the same position, and stack the anode end plate 13, anode PVC gasket 12, anode flow field plate 11, anode polytetrafluoroethylene gasket 10, anode porous transport layer 9, proton exchange membrane 8 coated with catalyst layer, cathode porous transport layer 7, cathode polytetrafluoroethylene gasket 6, cathode flow field plate 5, cathode PVC gasket 4, and cathode end plate 2 in sequence, and position them with M1.2 bolts 15 to ensure that the relative positions of the components do not shift, and cooperate with M1.2 nuts 1 to seal and tighten to ensure that there is no leakage of liquid or gas. The anode PVC gasket 12, the anode flow field plate 11, the cathode flow field plate 5 and the cathode PVC gasket 4 are all provided with a symmetrical R1.5mm circular through hole 13 and a R1.5mm circular through hole 22 as the upper gas-liquid inlet and outlet and the lower gas-liquid inlet and outlet to transmit water and gas; the anode flow field plate 11 and the cathode flow field plate 5 are provided with two parallel square grooves with a width of 1mm and a depth of 0.5mm as gas and liquid flow channels 21 from the upper gas-liquid inlet and outlet to the lower gas-liquid inlet and outlet on the side of the proton exchange membrane 8 coated with the catalyst layer, and the two parallel square grooves are spaced 0.5mm apart to naturally form a raised flow channel ridge with a width of 0.5mm; a raised flow channel ridge is naturally formed between the two square grooves; the anode end plate 13, the anode P VC gasket 12, anode flow field plate 11, anode polytetrafluoroethylene gasket 10, cathode polytetrafluoroethylene gasket 6, cathode flow field plate 5, cathode PVC gasket 4 and cathode end plate 2 are all made into an I-shaped structure with the same width at the top and bottom and narrower in the middle, forming a groove with a length of 6mm and a width of 2mm; the upper ends of the anode flow field plate 11 and the cathode flow field plate 5 are extended to be provided with 8*4mm rectangular electrodes; the anode end plate 13 and the cathode end plate 2 extend outwardly on the side facing away from the proton exchange membrane 8 coated with the catalyst layer to form an upper boss 14 and a lower boss 16 with a diameter of 6mm and a height of 2mm, and tapped with M3 internal threaded holes; the anode polytetrafluoroethylene gasket 10 and the cathode polytetrafluoroethylene gasket 6 are both provided with a 10*4mm rectangular through hole 19 in the middle;

[0056] The current degradation module includes a programmable DC power supply 23 and a 4MM banana plug to flat test wire 32; the programmable DC power supply 23 is connected to the anode flow field plate 11 and the rectangular electrode extending from the upper end of the cathode flow field plate 5 of the micro PEM electrolyzer 24 through the 4MM banana plug to flat test wire 32.

[0057] The deionized water circulation module includes a deionized water tank 28, a digital display peristaltic pump 27, a PVC hose 33, a reducer straight-through connector 34 and a quick-insert straight-through connector 35; the upper boss 14 and the lower boss 16 of the anode end plate 13 of the micro PEM electrolyzer 24, and the upper boss 14 and the lower boss 16 of the cathode end plate 2 are respectively connected to one end of the quick-insert straight-through connector 35 through threaded cooperation, and the other end of the quick-insert straight-through connector 35 is respectively connected to the three-way connector through the PVC hose 33, and is connected to the deionized water tank 28 and the digital display peristaltic pump 27 through the PVC hose 33 to form a water circulation;

[0058] The temperature control module includes a 12V switching power supply 31, a digital display intelligent temperature controller 29, a solid-state relay 30, a platinum resistor 26, and high-temperature ceramic heating plates 25 respectively attached to the left and right sides 18 of the I-shaped structure of the micro PEM electrolyzer; the digital display intelligent temperature controller 29 and the platinum resistor 26 attached to the end surface of the anode end plate 13 are connected to form a temperature sensing circuit, and the 12V switching power supply 31, the digital display intelligent temperature controller 29, the solid-state relay 30 and the high-temperature ceramic heating plate 25 are connected to form a heating circuit. The platinum resistor 26 is rectangular in shape, and the number of high-temperature ceramic heating plates 25 is 2, and the shape is rectangular.

[0059] A method for accelerating degradation of a PEM electrolyzer membrane electrode accelerated degradation system comprises the following steps:

[0060] S1: Run the deionized water circulation module: Make the deionized water flow rate into the PEM electrolyzer membrane electrode reach 1ml / min, and make the PEM electrolyzer membrane electrode fully wetted. The specific steps are as follows:

[0061] S1.1: inject 50 ml of deionized water into the deionized water tank 28;

[0062] S1.2: Connect the power supply of the digital display peristaltic pump 27 and turn on the switch of the digital display peristaltic pump 27;

[0063] S1.3: Adjust the set water delivery flow rate of the digital display peristaltic pump 27 to 1 ml / min, and wait for the actual flow rate displayed to stabilize at 1 ml / min before proceeding to the next step;

[0064] S2: Run the temperature control module to keep the PEM electrolyzer membrane electrode in a constant temperature environment of 90°C. The specific steps are as follows:

[0065] S2.1: Connect the power supply of the digital display intelligent temperature controller 29 and turn on the switch of the digital display intelligent temperature controller 29;

[0066] S2.2: Adjust the set temperature of the digital display intelligent temperature controller 29 to 90°C, and wait for the actual temperature to stabilize at 90°C before proceeding to the next step;

[0067] S3: Run the current degradation module to apply current circulation to the PEM electrolyzer membrane electrode. The specific steps are as follows:

[0068] S3.1: Connect the programmable DC power supply 23 and turn on the switch of the programmable DC power supply 23;

[0069] S3.2: Connect the programmable DC power supply 23 to the microcomputer via a USB communication cable;

[0070] S3.3: adjusting the output of the programmable DC power supply 23 to a constant current cycle of 4A / 15s and 0A / 15s in the microcomputer program;

[0071] The effective area of ​​the membrane electrode of the PEM electrolyzer is 0.4*1.0mm. According to the current density calculation formula:

[0072] J=I / A

[0073] Where I is the current, A is the effective area of ​​the PEM electrolyzer membrane electrode;

[0074] The current density applied to the PEM electrolyzer membrane electrode is 10A / cm 2 / 15s, 0A / cm 2 / 15s;

[0075] S4: The PEM electrolyzer membrane electrode completes 500 current density cycles, and the current degradation module, the deionized water circulation module, and the temperature control module are turned off in sequence to cool the PEM electrolyzer membrane electrode to room temperature.

[0076] An in-situ detection method of an in-situ detection system using an accelerated degradation method of a PEM electrolyzer membrane electrode accelerated degradation system, the in-situ detection system comprising a micro PEM electrolyzer, an XCT module, and an electrochemical characterization module; the XCT module comprises an X-ray source 37 and an X-ray signal receiver 38 located on the left and right sides of an imaging area; the electrochemical characterization module comprises an electrochemical workstation 39;

[0077] The in-situ detection method includes the following steps:

[0078] S1: When the PEM electrolyzer membrane electrode is in the initial state and every time 500 current density cycles are completed, the PEM electrolyzer membrane electrode accelerated degradation system is turned off, and the PEM electrolyzer membrane electrode accelerated degradation system is cooled to room temperature, and the micro PEM electrolyzer 24 is removed from the PEM electrolyzer membrane electrode accelerated degradation system;

[0079] S2: Start the XCT module, use a commercial micro XCT machine to take in-situ images of the PEM electrolyzer membrane electrode that has undergone current density cycling, set the imaging area to be 13 mm away from the X-ray source (44), and 758 mm away from the X-ray signal receiver (45), set the acceleration voltage to 100 kV and the power to 12 W, and after the image is taken, use the matching image reconstruction software to obtain a three-dimensional image of the PEM electrolyzer membrane electrode with a resolution of 1.7 μm;

[0080] S3: Start the electrochemical characterization module, turn on the switch of the electrochemical workstation 39, adjust the working mode of the electrochemical workstation to polarization curve test and electrochemical impedance spectrum test in sequence, and perform in-situ electrochemical performance test on the PEM electrolyzer membrane electrode that has undergone current density cycling;

[0081] S4: Repeat S1, S2, and S3 until the three-dimensional image of the membrane electrode of the PEM electrolyzer shows that the membrane crack area accounts for 15% of the failure condition or the membrane thickness is reduced by 15%, or the voltage decay rate reaches 15%, and the membrane electrode is judged to be failed and the test is terminated;

[0082] S5: Based on the XCT three-dimensional images, polarization curves, and electrochemical impedance spectroscopy of the above-mentioned cycle stages, an in-situ comparative analysis of the degradation of the PEM electrolyzer membrane electrode was conducted to explore the degradation rules and mechanisms.

[0083] The PEM electrolyzer membrane electrode accelerated degradation system of the present invention restores the PEM electrolyzer components and structures used in actual production, creates a real PEM electrolyzer production condition environment, and adopts high-frequency current density circulation to accelerate the chemical degradation of the PEM electrolyzer membrane electrode; the PEM electrolyzer membrane electrode in-situ detection system composed of a micro PEM electrolyzer, an XCT module, and an electrochemical characterization module innovatively applies XCT technology to the field of PEM electrolyzer membrane electrode detection, and effectively makes up for the shortcomings of existing microscopic detection technologies such as SEM and TEM that are incomplete, non-in-situ, and non-repeatable by providing the full three-dimensional internal structure of the PEM electrolyzer, non-destructive detection, in-situ imaging, and quantitative analysis. Combined with electrochemical characterization, the interaction and microstructural changes of key components such as catalyst layers, membranes, and porous transport layers during operation can be analyzed in detail, which is helpful to understand the degradation mechanisms such as chemical degradation of the membrane and deactivation of the catalyst.

[0084] The PEM electrolyzer membrane electrode accelerated degradation system of the present invention innovatively reduces the design of a micro PEM electrolyzer, and its size is much smaller than the size of the common PEM electrolyzers on the market, so as to adapt to the high-resolution in-situ detection of commercial micro XCT and the focused observation of the vulnerable areas of the membrane electrode. Compared with the X-rays excited by the synchrotron radiation light source, the commercial micro XCT has the characteristics of moderate energy control, low radiation dose, small sample damage, and low thermal effect. It can maintain the original properties of the PEM electrolyzer after multiple XCT imaging, and has the advantages of simple operation, rapid imaging, and easy maintenance.

[0085] The current degradation module of the PEM electrolyzer membrane electrode accelerated degradation system of the present invention can be used according to the PEM electrolyzer membrane electrode chemical degradation test method at 0A / cm 2 -10A / cm 2 High-frequency DC square wave circulation can be achieved within the range, and the programmable DC power supply can be connected to a microcomputer via a USB communication cable, and the PEM electrolyzer current circulation coupled with clean energy such as wind, light, and electricity can be edited and output. Compared with the ordinary current density cycle application method, the current degradation module of the PEM electrolyzer membrane electrode accelerated degradation system can simulate the dynamic behavior of the electrolyzer under actual operating conditions, greatly reducing the test time, and can simulate the intermittent and fluctuating output of wind and solar energy, providing a more realistic accelerated degradation environment.

[0086] The present invention innovatively applies a micro PEM electrolyzer and XCT technology to the field of PEM electrolyzer membrane electrode degradation detection. Aiming at the shortcomings of existing PEM electrolyzer membrane electrode degradation methods such as long time consumption and poor coupling with the actual degradation environment, a PEM electrolyzer membrane electrode accelerated degradation system is invented in combination with the characteristics of the micro design of the PEM electrolyzer, which significantly improves the degree of reduction of the actual PEM electrolyzer chemical degradation environment. By utilizing the in-situ detection system of the PEM electrolyzer membrane electrode accelerated degradation system, non-destructive in-situ detection of PEM electrolyzer membrane electrode degradation is achieved.

[0087] Although the embodiments and drawings of the present invention are disclosed for illustrative purposes, those skilled in the art will appreciate that various substitutions, changes and modifications are possible without departing from the spirit and scope of the present invention and the appended claims. Therefore, the scope of the present invention is not limited to the contents disclosed in the embodiments and drawings.

Claims

1. A PEM electrolyzer membrane electrode accelerated degradation system, characterized in that: it comprises a micro PEM electrolyzer (24), a current degradation module, a deionized water circulation module and a temperature control module; the current degradation module, the deionized water circulation module and the temperature control module are respectively connected to the PEM electrolyzer (24); The current degradation module comprises a programmable DC power supply (23) and a banana plug to flat port test wire (32); the programmable DC power supply (23) is connected to a micro PEM electrolyzer (24) via the banana plug to flat port test wire (32); The deionized water circulation module comprises a deionized water tank (28), a digital display peristaltic pump (27), a PVC hose (33), a reducer straight-through connector (34) and a quick-insert straight-through connector (35); the micro PEM electrolyzer (24) is connected to one end of the quick-insert straight-through connector (35) through threaded engagement, and the other end of the quick-insert straight-through connector (35) is connected to a three-way connector through a PVC hose (33), and is connected to the deionized water tank (28) and the digital display peristaltic pump (27) through the PVC hose (33), thereby forming a water circulation; The temperature control module comprises a switching power supply (31), a digital display intelligent temperature controller (29), a solid-state relay (30), a platinum resistor (26), and high-temperature ceramic heating plates (25) respectively attached to the left and right sides (18) of an I-shaped structure of a micro PEM electrolyzer; the digital display intelligent temperature controller (29) and the platinum resistor (26) are connected to form a temperature sensing circuit, and the switching power supply (31), the digital display intelligent temperature controller (29), the solid-state relay (30), and the high-temperature ceramic heating plate (25) are connected to form a heating circuit.

2. The PEM electrolyzer membrane electrode accelerated degradation system according to claim 1 is characterized in that: the micro PEM electrolyzer (24) comprises an anode end plate (13), an anode PVC gasket (12), an anode flow field plate (11), an anode polytetrafluoroethylene gasket (10), an anode porous transport layer (9), a proton exchange membrane (8) coated with a catalyst layer, a cathode porous transport layer (7), a cathode polytetrafluoroethylene gasket (6), a cathode flow field plate (5), a cathode PVC gasket (4) and a cathode end plate (2), wherein the anode end plate (13), the anode PVC gasket (12), the anode flow field plate (11), the anode polytetrafluoroethylene gasket (10), the anode porous transport layer (9), a proton exchange membrane (8) coated with a catalyst layer, a cathode porous transport layer (7), a cathode polytetrafluoroethylene gasket (6), a cathode flow field plate (5), a cathode PVC gasket (4) and a cathode end plate (2). (10), the cathode polytetrafluoroethylene gasket (6), the cathode flow field plate (5), the cathode PVC gasket (4) and the cathode end plate (2) are all tapped with threaded holes (17) at the same position, and the anode end plate (13), the anode PVC gasket (12), the anode flow field plate (11), the anode polytetrafluoroethylene gasket (10), the anode porous transport layer (9), the proton exchange membrane coated with the catalyst layer (8), the cathode porous transport layer (7), the cathode polytetrafluoroethylene gasket (6), the cathode flow field plate (5), the cathode PVC gasket (4) and the cathode end plate (2) are stacked up in sequence, positioned by bolts (15), and sealed and tightened in cooperation with nuts (1); The anode PVC gasket (12), the anode flow field plate (11), the cathode flow field plate (5) and the cathode PVC gasket (4) are all provided with a circular through hole 1 (3) and a circular through hole 2 (22) which are symmetrical in the upper and lower directions as the upper gas-liquid inlet and outlet and the lower gas-liquid inlet and outlet for transmitting water and gas; the anode flow field plate (11) and the cathode flow field plate (5) are provided with two parallel square grooves from the upper gas-liquid inlet and outlet to the lower gas-liquid inlet and outlet on the side of the proton exchange membrane (8) coated with the catalyst layer as gas and liquid flow channels (21), and a raised flow channel ridge is naturally formed in the middle of the two square grooves; the anode end plate (13), the anode PVC gasket (12) and the anode flow field plate (11), the anode polytetrafluoroethylene gasket (10), the cathode polytetrafluoroethylene gasket (6), the cathode flow field plate (5), the cathode PVC gasket (4) and the cathode end plate (2) are all made into an I-shaped structure with the same width at the top and bottom and a narrower middle; the upper ends of the anode flow field plate (11) and the cathode flow field plate (5) are extended to be provided with rectangular electrodes; the anode end plate (13) and the cathode end plate (2) extend outwardly on the side facing away from the proton exchange membrane (8) coated with the catalyst layer to form an upper boss (14) and a lower boss (16), and tapped with internal threaded holes; the anode polytetrafluoroethylene gasket (10) and the cathode polytetrafluoroethylene gasket (6) are both provided with a rectangular through hole (19) in the middle; The programmable DC power supply (23) is connected to the rectangular electrodes extending from the upper ends of the anode flow field plate (11) and the cathode flow field plate (5) of the micro PEM electrolyzer (24) through banana plug-to-flat test wires (32). The upper boss (14) and lower boss (16) of the anode end plate (13) and the upper boss (14) and lower boss (16) of the cathode end plate (2) of the micro PEM electrolyzer (24) are respectively connected to one end of the quick-insert straight-through connector (35) through threaded engagement.

3. A method for accelerating degradation of a PEM electrolyzer membrane electrode accelerated degradation system according to claim 1, characterized in that it comprises the following steps: S1: Run the deionized water circulation module: Make the deionized water flow rate into the PEM electrolyzer membrane electrode reach 1ml / min, and make the PEM electrolyzer membrane electrode fully wetted. The specific steps are as follows: S1.1: Inject 50 ml of deionized water into the deionized water tank (28); S1.2: Connect the power supply of the digital display peristaltic pump (27) and turn on the switch of the digital display peristaltic pump (27); S1.3: Adjust the set water delivery flow rate of the digital peristaltic pump (27) to 1 ml / min, and wait for the actual flow rate displayed to stabilize at 1 ml / min before proceeding to the next step; S2: Run the temperature control module to keep the PEM electrolyzer membrane electrode in a constant temperature environment of 90°C. The specific steps are as follows: S2.1: Connect the power supply of the digital display intelligent temperature controller (29) and turn on the switch of the digital display intelligent temperature controller (29); S2.2: Adjust the set temperature of the digital display intelligent temperature controller (29) to 90°C, and wait for the actual temperature displayed to stabilize at 90°C before proceeding to the next step; S3: Run the current degradation module to apply current circulation to the PEM electrolyzer membrane electrode. The specific steps are as follows: S3.1: Connect the programmable DC power supply (23) and turn on the switch of the programmable DC power supply (23); S3.2: Connect the programmable DC power supply (23) to the microcomputer via a USB communication cable; S3.3: adjusting the output of the programmable DC power supply (23) to a constant current cycle of 4A / 15s and 0A / 15s in the microcomputer program; The effective area of ​​the membrane electrode of the PEM electrolyzer is 0.4*1.0mm. According to the current density calculation formula: J=I / A Where I is the current, A is the effective area of ​​the PEM electrolyzer membrane electrode; The current density applied to the PEM electrolyzer membrane electrode is 10A / cm 2 / 15s, 0A / cm 2 / 15s; S4: The PEM electrolyzer membrane electrode completes 500 current density cycles, and the current degradation module, the deionized water circulation module, and the temperature control module are turned off in sequence to cool the PEM electrolyzer membrane electrode to room temperature.

4. An in-situ detection method of an in-situ detection system using the accelerated degradation method of the PEM electrolyzer membrane electrode accelerated degradation system according to claim 2, characterized in that: The in-situ detection system comprises a micro PEM electrolyzer, an XCT module, and an electrochemical characterization module; the XCT module comprises an X-ray source (37) and an X-ray signal receiver (38) located on the left and right sides of an imaging area; the electrochemical characterization module comprises an electrochemical workstation (39); The in-situ detection method includes the following steps: S1: When the PEM electrolyzer membrane electrode is in the initial state and every time 500 current density cycles are completed, the PEM electrolyzer membrane electrode accelerated degradation system is turned off, and after the PEM electrolyzer membrane electrode accelerated degradation system is cooled to room temperature, the micro PEM electrolyzer (24) is removed from the PEM electrolyzer membrane electrode accelerated degradation system; S2: Start the XCT module, use a commercial micro XCT machine to take in-situ images of the PEM electrolyzer membrane electrode that has undergone current density cycling, set the imaging area to be 13 mm away from the X-ray source (44), and 758 mm away from the X-ray signal receiver (45), set the acceleration voltage to 100 kV and the power to 12 W, and after the image is taken, use the matching image reconstruction software to obtain a three-dimensional image of the PEM electrolyzer membrane electrode with a resolution of 1.7 μm; S3: starting the electrochemical characterization module, turning on the switch of the electrochemical workstation (39), adjusting the working mode of the electrochemical workstation to polarization curve test and electrochemical impedance spectrum test in sequence, and performing in-situ electrochemical performance test on the PEM electrolyzer membrane electrode that has undergone current density cycling; S4: Repeat S1, S2, and S3 until the three-dimensional image of the membrane electrode of the PEM electrolyzer shows that the membrane crack area accounts for 15% of the failure condition or the membrane thickness is reduced by 15%, or the voltage decay rate reaches 15%, and the membrane electrode is judged to be failed and the test is terminated; S5: Based on the XCT three-dimensional images, polarization curves, and electrochemical impedance spectroscopy of the above-mentioned cycle stages, an in-situ comparative analysis of the degradation of the PEM electrolyzer membrane electrode was performed.

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