Accelerated degradation method, in-situ detection system and in-situ detection method for accelerating degradation of system by using PEM electrolyzer membrane electrode

Abstract

The application relates to an accelerated degradation method of an accelerated degradation system of a PEM electrolytic cell membrane electrode, an in-situ detection system and an in-situ detection method. The accelerated degradation system of the PEM electrolytic cell membrane electrode comprises a micro PEM electrolytic cell, 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, the shortcomings that the existing PEM electrolytic cell is too large to be shot at high resolution by a commercial micro XCT machine and that the existing PEM electrolytic cell membrane electrode degradation visualization detection technology is non-in-situ and non-repeatable 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 application relates to the technical field of in-situ detection of a PEM electrolyzer membrane electrode, and particularly relates to an accelerated degradation method, an in-situ detection system and an in-situ detection method of a PEM electrolyzer membrane electrode accelerated degradation system. BACKGROUND

[0002] The accelerated consumption of fossil fuels and its high carbon dioxide emissions have prompted people to seek alternative fuels. Renewable energy is considered a promising choice to replace 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 reconverted into electricity through fuel cells. Among various 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. But 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 the PEM electrolyzer, the proton exchange membrane provides a transport channel that only allows water molecules and hydronium ions to pass through, transporting protons from the anode to the cathode of the electrolyzer, forming a path for ion transfer inside the electrolyzer. The performance decline of the PEM electrolyzer proton exchange membrane is mainly due to chemical degradation caused by the load current. Chemical degradation forms hydrogen peroxide or free radicals on the catalyst, and the proton exchange membrane is attacked by free radicals to produce "decompression reactions" to thin the membrane, exacerbating the cross of product gases, further accelerating the production of free radicals, resulting in a significant reduction in the service life of the proton exchange membrane, and the proton exchange membrane is more prone to puncture, tearing and cracking. The thinning of the proton exchange membrane and the generation of defects will cause the performance of the electrolyzer to deteriorate seriously, and there is a great safety hazard. Mechanical performance tests such as tensile strength, elongation at break, Young's modulus, and dimensional change rate are commonly used for PEM electrolyzer proton exchange membrane performance testing, but none of these methods designs chemical durability testing. Therefore, it is urgent to design a chemical accelerated degradation system to provide a more practical PEM electrolyzer operating condition for the proton exchange membrane accelerated degradation environment, and to detect the electrochemical performance of the PEM electrolyzer membrane electrode that has experienced this chemical accelerated degradation and the visual detection of defects.

[0003] Scanning electron microscopy (SEM) is commonly used for high-resolution microscopic characterization of PEM electrolyzer membrane electrodes, but is limited by the following aspects: SEM imaging mainly focuses on the surface of the sample, and it is difficult to obtain information about the internal structure; the sample preparation process for SEM 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 requires a vacuum environment, and PEM electrolyzer membrane electrodes may change under vacuum conditions, affecting the observation of their original state; SEM usually images the sample under static conditions, making it difficult to achieve in-situ observation of 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 transmitted X-rays through detectors, obtaining multi-angle projection data of the object. Through computer algorithms, the projection data is reconstructed into a three-dimensional image of the object's interior, providing detailed information about the object's internal structure. XCT allows researchers to observe the microstructure changes of membrane electrodes in real time during electrolyzer operation under actual working conditions; XCT is a non-destructive testing technology that does not require physical destruction or cutting of the sample, and XCT can provide detailed information about the sample's interior, and the same sample can be scanned multiple times and monitored under different time points or operating conditions without damaging the sample; XCT can provide high-resolution three-dimensional images, allowing researchers to observe the microstructure of 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 information about the structure and performance of PEM electrolyzer membrane electrodes, which helps to deeply study their working mechanism and degradation process and promotes the development and optimization of PEM electrolyzer technology.

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

[0006] The prior art mainly focuses on cost reduction and efficiency improvement of key components of PEM electrolytic cell and PEM electrolytic cell stack, and there are few studies on the formation and development process of chemical degradation of PEM electrolytic cell membrane electrode, and the full three-dimensional internal structure, non-destructive detection, in-situ imaging, material contrast and element distribution analysis, and quantitative analysis means of PEM electrolytic cell membrane electrode are not perfect. In order to more comprehensively and accurately understand the microstructure and dynamic changes of PEM electrolytic cell membrane electrode after accelerated chemical degradation, XCT in-situ detection is introduced, a micro PEM electrolytic cell and a corresponding PEM electrolytic cell membrane electrode accelerated degradation system are designed, and an in-situ detection system of the PEM electrolytic cell membrane electrode accelerated degradation system including an XCT module and an electrochemical characterization module is designed, so as to realize in-situ and non-destructive detection of the PEM electrolytic cell membrane electrode.

[0007] The accelerated chemical degradation experiment of the PEM electrolytic cell can not only deeply explore the degradation mechanism and provide a scientific basis for the optimization of the membrane electrode material and process, but also can improve the performance and service life of the electrolytic cell, reduce the cost, promote the development of industry technical standards, support the verification of theoretical models, accelerate the research and development period, and improve the product competitiveness, so as to promote the progress and application of the PEM electrolytic cell technology. SUMMARY

[0008] The purpose of the present application is to overcome the shortcomings of the prior art, provide an accelerated degradation method, an in-situ detection system and an in-situ detection method using a PEM electrolytic cell membrane electrode accelerated degradation system, and through a micro PEM electrolytic cell, the membrane electrode can be subjected to accelerated degradation and then subjected to in-situ micro characterization using a laboratory XCT system, which overcomes the shortcomings of the prior art that the large size of the PEM electrolytic cell cannot be used for high-resolution shooting in a commercial micro XCT machine, and the visual detection technology for the degradation of the PEM electrolytic cell membrane electrode is non-in-situ and non-repeatable, so as to realize in-situ, non-destructive and high-resolution three-dimensional detection of the PEM electrolytic cell membrane electrode.

[0009] The technical problems of the present application are solved by the following technical solutions:

[0010] A PEM electrolytic cell membrane electrode accelerated degradation system, comprising a micro PEM electrolytic cell, 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 connected with the PEM electrolytic cell respectively;

[0011] The current degradation module comprises a programmable DC power supply and a banana plug to flat test lead; the programmable DC power supply is connected to the micro PEM electrolytic cell through the banana plug to flat test lead respectively;

[0012] The deionized water circulation module comprises a deionized water tank, a digital display peristaltic pump, a PVC hose, a variable diameter straight connector and a quick plug straight connector; one end of the micro PEM electrolytic cell is connected with the quick plug straight connector through thread cooperation, the other end of the quick plug straight connector is connected with a three-way connector through the PVC hose, the deionized water tank and the digital display peristaltic pump are connected through the PVC hose, and the water circulation is formed;

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

[0014] Further, the micro PEM electrolytic cell comprises an anode end 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 end plate, 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 threaded at the same position, and the anode end 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 end plate are stacked in turn, positioned by bolts and sealed and fastened with nuts; the anode PVC gasket, the anode flow field plate, the cathode flow field plate and the cathode PVC gasket are all provided with upper and lower symmetrical circular through holes one and circular through holes two as upper and lower gas-liquid inlets and outlets for transmitting water and gas; the anode flow field plate and the cathode flow field plate are provided with two parallel square grooves as gas and liquid flow channels from the upper gas-liquid inlet to the lower gas-liquid outlet on the side of the proton exchange membrane coated with a catalyst layer, and a convex flow channel ridge is naturally formed between 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 above and below and a relatively narrow middle part; the upper ends of the anode flow field plate and the cathode flow field plate are both extended to be provided with rectangular electrodes; the anode end plate and the cathode end plate are both outwardly extended on the side away from the proton exchange membrane coated with a catalyst layer to form upper and lower bosses and are provided with internal threaded holes;

[0015] The programmable direct current power supply is connected to the upper end of the extended rectangular electrode of the anode flow field plate and the cathode flow field plate of the micro PEM electrolytic cell through a banana plug.

[0016] The upper boss and lower boss of the anode end plate and the upper boss and lower boss of the cathode end plate of the micro PEM electrolytic cell are respectively connected to one end of the quick plug-through connector through threaded connection.

[0017] An accelerated degradation method using a PEM electrolytic cell membrane electrode accelerated degradation system, comprising the following steps:

[0018] S1: Run the deionized water circulation module: make the deionized water flow into the PEM electrolytic cell membrane electrode reach 1ml / min, and make the PEM electrolytic cell membrane electrode fully wet, the specific steps are as follows:

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

[0020] S1.2: Turn on the digital peristaltic pump power supply and open the digital peristaltic pump switch;

[0021] S1.3: Adjust the set water 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 make the PEM electrolytic cell membrane electrode in a constant temperature environment of 90℃, the specific steps are as follows:

[0023] S2.1: Turn on the digital intelligent temperature controller power supply and open the digital intelligent temperature controller switch;

[0024] S2.2: Adjust the set temperature of the digital 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, and apply a current cycle to the PEM electrolytic cell membrane electrode, the specific steps are as follows:

[0026] S3.1: Turn on the programmable direct current power supply and open the programmable direct current power supply switch;

[0027] S3.2: Connect the programmable direct current power supply to the microcomputer through the USB communication line;

[0028] S3.3: Adjust the programmable direct current power supply output to 4A / 15s, 0A / 15S constant current cycle in the microcomputer program;

[0029] The effective area of the PEM electrolytic cell membrane electrode is 0.4*1.0mm, according to the current density calculation formula:

[0030] J = I / A

[0031] where I is the current magnitude, and A is the PEM cell membrane electrode effective area;

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

[0033] S4: The PEM cell membrane electrode completes 500 current density cycles, and the current degradation module, the deionized water circulation module, and the temperature control module are sequentially turned off, so that the PEM cell membrane electrode is cooled to room temperature.

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

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

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

[0037] S1: The initial state of the PEM cell membrane electrode and every time 500 current density cycles are completed, the PEM cell membrane electrode accelerated degradation system is turned off, and the micro-PEM cell is taken out from the PEM cell membrane electrode accelerated degradation system after the PEM cell membrane electrode accelerated degradation system is cooled to room temperature;

[0038] S2: The XCT module is started, a commercial micro-XCT machine is used to take in-situ pictures of the PEM cell membrane electrode that has experienced current density cycles, the imaging area is set to be 13 mm away from the X-ray source and 758 mm away from the X-ray signal receiver, the acceleration voltage is set to be 100 kV, and the power is set to be 12 W, after the pictures are taken, a matching image reconstruction software is used to obtain a three-dimensional image of the PEM cell membrane electrode with a resolution of 1.7 μm;

[0039] S3: The electrochemical characterization module is started, the electrochemical workstation switch is turned on, the electrochemical workstation working mode is adjusted to be polarization curve test and electrochemical impedance spectroscopy test in sequence, and in-situ electrochemical performance test is performed on the PEM cell membrane electrode that has experienced current density cycles;

[0040] S4: S1, S2, and S3 are repeated until the three-dimensional image of the PEM cell membrane electrode shows that the failure condition of the membrane crack area ratio reaching 15% or the membrane thickness thinning by 15% or the voltage attenuation rate reaching 15% is met, the membrane electrode is determined to be failed, and the test is terminated;

[0041] S5: Based on the above-mentioned each cycle stage XCT three-dimensional image, polarization curve, electrochemical impedance spectrum, PEM electrolytic cell membrane electrode degradation situation carries out in situ comparative analysis.

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

[0043] 1、The PEM electrolytic cell membrane electrode accelerated degradation system of the present application reduces the actual production application PEM electrolytic cell assembly and structure, creates a real PEM electrolytic cell production condition environment, and uses high-frequency current density cycle to accelerate the chemical degradation of PEM electrolytic cell membrane electrode; the PEM electrolytic cell membrane electrode in-situ detection system composed of a miniature PEM electrolytic cell, an XCT module and an electrochemical characterization module innovatively applies XCT technology to the PEM electrolytic cell membrane electrode detection field, effectively makes up for the shortcomings of existing microscopic detection technologies such as SEM and TEM, that is, not comprehensive, non-in situ and non-reproducible, and in combination with electrochemical characterization, the interaction and microstructure change of catalyst layer, membrane and porous transport layer and other key components during operation can be analyzed in detail, which helps to understand the degradation mechanism such as chemical degradation of the membrane and deactivation of the catalyst.

[0044] 2、The PEM electrolytic cell membrane electrode accelerated degradation system of the present application innovatively designs a miniature PEM electrolytic cell, which is much smaller than the size of the PEM electrolytic cell commonly seen on the market, to adapt to the high-resolution in-situ detection of a commercial miniature XCT and the key observation of the vulnerable area of the membrane electrode. Compared with the X-ray generated by the synchrotron radiation light source, the commercial miniature XCT has the characteristics of moderate energy control, low radiation dose, small sample damage and low thermal effect, can maintain the original properties of the PEM electrolytic cell after multiple XCT imaging, and has the advantages of simple operation, fast imaging and easy maintenance.

[0045] 3、The current degradation module of the PEM electrolytic cell membrane electrode accelerated degradation system of the present application can realize high-frequency direct current square wave cycle in the range of 0A / cm 2 -10A / cm 2 The programmable direct current power supply can be connected to the microcomputer through the USB communication line, and the PEM electrolytic cell current cycle 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 electrolytic cell membrane electrode accelerated degradation system can simulate the dynamic behavior of the electrolytic cell under actual operating conditions, greatly reduce the test time, and can simulate the intermittency and volatility of wind-solar-electric energy output, and provide a more realistic accelerated degradation environment.

[0046] 4, The application innovatively applies the micro PEM electrolytic cell and XCT technology to the PEM electrolytic cell membrane electrode degradation detection field, a PEM electrolytic cell membrane electrode accelerated degradation system is invented in combination with the characteristics of the micro design of the PEM electrolytic cell, the real PEM electrolytic cell chemical degradation environment is significantly improved in reduction degree, and the in-situ detection system of the PEM electrolytic cell membrane electrode accelerated degradation system is used to realize the non-destructive in-situ detection of the PEM electrolytic cell membrane electrode degradation. BRIEF DESCRIPTION OF DRAWINGS

[0047] Figure 1 It is a schematic diagram of the PEM electrolytic cell membrane electrode accelerated degradation system of the application;

[0048] Figure 2 It is a partial enlarged view of the PEM electrolytic cell membrane electrode accelerated degradation system of the application;

[0049] Figure 3 It is a structural schematic diagram of the micro PEM electrolytic cell of the PEM electrolytic cell membrane electrode accelerated degradation system of the application;

[0050] Figure 4 It is a schematic diagram of the PEM electrolytic cell membrane electrode in-situ detection system of the application.

[0051] In the drawings:

[0052] 1-nut, 2-cathode end plate, 3-round through hole one, 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 thread hole, 18-I-shaped groove, 19-rectangular through hole, 20-membrane electrode positioning groove, 21-flow channel, 22-round through hole two, 23-programmable DC power supply, 24-micro PEM electrolytic cell, 25-high-temperature ceramic heating sheet, 26-platinum resistance, 27-digital peristaltic pump, 28-deionized water tank, 29-digital intelligent temperature controller, 30-solid-state relay, 31-switching power supply, 32-banana plug to flat test lead, 33-PVC hose, 34-variable diameter straight connector, 35-quick plug straight connector, 36-three-way connector, 37-X-ray source, 38-X-ray signal receiver, 39-electrochemical workstation. DETAILED DESCRIPTION

[0053] The application will be further described in detail through specific embodiments below, the following embodiments are only descriptive and not limiting, and the protection scope of the application cannot be limited by the following embodiments.

[0054] As shown in Figures 1-4 A PEM electrolyzer membrane electrode accelerated degradation system, including 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 connected with the PEM electrolyzer respectively; the micro PEM electrolyzer with reduced design has a whole height of 30mm, a width of 12mm and a thickness of 8mm; the imaging area is a rectangle with a length of 8mm and a width of 6mm.

[0055] Miniature PEM electrolyzer 24, including anode end plate 13, anode PVC gasket 12, anode flow field plate 11, anode PTFE gasket 10, anode porous transport layer 9, catalyst-coated proton exchange membrane 8, cathode porous transport layer 7, cathode PTFE gasket 6, cathode flow field plate 5, cathode PVC gasket 4 and cathode end plate 2, anode end plate 13, anode PVC gasket 12, anode flow field plate 11, anode PTFE gasket 10, cathode PTFE gasket 6, cathode flow field plate 5, cathode PVC gasket 4 and cathode end plate 2 are all tapped with M1.2 internal threaded holes 17, and anode end plate 13, anode PVC gasket 12, anode flow field plate 11, anode PTFE gasket 10, anode porous transport layer 9, catalyst-coated proton exchange membrane 8, cathode porous transport layer 7, cathode PTFE gasket 6, cathode flow field plate 5, cathode PVC gasket 4 and cathode end plate 2 are stacked in order, positioned by M1.2 bolts 15, to ensure that the relative positions of the components do not shift, and sealed and fastened with M1.2 nuts 1 to ensure that there is no liquid or gas leakage. Anode PVC gasket 12, anode flow field plate 11, cathode flow field plate 5 and cathode PVC gasket 4 are all provided with upper and lower symmetric R1.5mm circular through holes 3 and R1.5mm circular through holes 22 as upper and lower gas-liquid inlets and outlets for water and gas transmission; anode flow field plate 11 and 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 to the lower gas-liquid outlet on the side of catalyst-coated proton exchange membrane 8, with a spacing of 0.5mm between the two parallel square grooves, naturally forming a convex 0.5mm wide flow channel ridge; the middle of the two square grooves naturally forms a convex flow channel ridge; anode end plate 13, anode PVC gasket 12, anode flow field plate 11, anode PTFE gasket 10, cathode PTFE gasket 6, cathode flow field plate 5, cathode PVC gasket 4 and cathode end plate 2 are all made into H-shaped structures with the same width from top to bottom and narrower in the middle, forming a 6mm long and 2mm wide groove; the upper ends of anode flow field plate 11 and cathode flow field plate 5 are both extended to form 8*4mm rectangular electrodes; anode end plate 13 and cathode end plate 2 are both extended outward on the side away from catalyst-coated proton exchange membrane 8 to form upper and lower bosses 14 and 16 with a diameter of 6mm and a height of 2mm, tapped with M3 internal threaded holes; anode PTFE gasket 10 and cathode PTFE gasket 6 are both provided with 10*4mm rectangular through holes 19 in the middle;

[0056] Current degradation module, including programmable DC power supply 23 and 4MM banana plug to flat test lead 32; programmable DC power supply 23 is connected to the upper end extended rectangular electrodes of anode flow field plate 11 and cathode flow field plate 5 of miniature PEM electrolyzer 24 through 4MM banana plug to flat test lead 32.

[0057] Deionized water circulation module, including deionized water tank 28, digital peristaltic pump 27, PVC hose 33, variable diameter straight connector 34 and quick plug straight connector 35; the boss 14 and the lower boss 16 on the anode end plate 13 of the micro PEM electrolytic cell 24, the boss 14 and the lower boss 16 on the cathode end plate 2 are respectively connected with one end of the quick plug straight connector 35 through thread cooperation, the other end of the quick plug straight connector 35 is respectively connected with the three-way connector through the PVC hose 33, the deionized water tank 28 and the digital peristaltic pump 27 are connected through the PVC hose 33, forming water circulation;

[0058] Temperature control module, including 12V switching power supply 31, digital intelligent temperature controller 29, solid state relay 30, platinum resistance 26 and high temperature ceramic heating sheet 25 respectively pasted on the left and right sides 18 of the micro PEM electrolytic cell I-shaped structure; the digital intelligent temperature controller 29 and the platinum resistance 26 pasted on the end face of the anode end plate 13 are connected to form a temperature sensing loop, the 12V switching power supply 31, the digital intelligent temperature controller 29, the solid state relay 30 and the high temperature ceramic heating sheet 25 are connected to form a heating loop. The shape of the platinum resistance 26 is rectangular, and the number of the high temperature ceramic heating sheet 25 is two, which is rectangular in shape.

[0059] An accelerated degradation method using PEM electrolytic cell membrane electrode accelerated degradation system, comprising the following steps:

[0060] S1: running deionized water circulation module: make the deionized water flow into the PEM electrolytic cell membrane electrode reach 1ml / min, and make the PEM electrolytic cell membrane electrode get fully wet, the specific steps are as follows:

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

[0062] S1.2: turn on the power of the digital peristaltic pump 27, and open the switch of the digital peristaltic pump 27;

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

[0064] S2: running temperature control module, making the PEM electrolytic cell membrane electrode in a constant temperature environment of 90℃, the specific steps are as follows:

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

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

[0067] S3: running current degradation module, current cycle is applied to PEM electrolytic cell membrane electrode, the specific steps are as follows:

[0068] S3.1: turn on the programmable DC power supply 23, open the programmable DC power supply 23 switch;

[0069] S3.2: connect the programmable DC power supply 23 to the microcomputer through the USB communication line;

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

[0071] The effective area of the PEM electrolytic cell membrane electrode is 0.4*1.0mm, according to the current density calculation formula:

[0072] J=I / A

[0073] Wherein I is the current size, A is the effective area of PEM electrolytic cell membrane electrode;

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

[0075] S4: PEM electrolytic cell membrane electrode completes 500 times of current density cycle, in turn, close the current degradation module, deionized water circulation module, temperature control module, and cool the PEM electrolytic cell membrane electrode to room temperature.

[0076] An in-situ detection method of an in-situ detection system of an accelerated degradation method of an accelerated degradation system using a PEM electrolytic cell membrane electrode, the in-situ detection system comprising a micro-PEM electrolytic cell, 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 the imaging area; the electrochemical characterization module comprises an electrochemical workstation 39;

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

[0078] S1: the initial state of the PEM electrolytic cell membrane electrode and every 500 times of current density cycle, close the PEM electrolytic cell membrane electrode accelerated degradation system, and cool the PEM electrolytic cell membrane electrode accelerated degradation system to room temperature, and take the micro-PEM electrolytic cell 24 from the PEM electrolytic cell membrane electrode accelerated degradation system;

[0079] S2: start the XCT module, use a commercial micro-CT machine to take in-situ pictures 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, after the shooting is completed, 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 electrochemical workstation 39 switch, and adjust the electrochemical workstation working mode 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;

[0081] S4: repeat S1, S2, S3 until the PEM electrolyzer membrane electrode three-dimensional image shows that the failure condition of the membrane crack area ratio reaching 15% or the membrane thickness thinning by 15% or the voltage attenuation rate reaching 15%, and then determine that the membrane electrode is failed, and terminate the test;

[0082] S5: based on the XCT three-dimensional image, polarization curve and electrochemical impedance spectroscopy of each cycle stage, in-situ comparative analysis is performed on the degradation of the PEM electrolyzer membrane electrode, and the degradation rule and mechanism are explored.

[0083] The PEM electrolyzer membrane electrode accelerated degradation system of the application reproduces the actual production application PEM electrolyzer assembly and structure, creates a real PEM electrolyzer production condition environment, uses high-frequency current density cycling 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 PEM electrolyzer membrane electrode detection field, provides PEM electrolyzer full three-dimensional internal structure, non-destructive detection, in-situ imaging and quantitative analysis and other advantages, effectively makes up for the shortcomings of existing microscopic detection technologies such as SEM and TEM, which are not comprehensive, non-in-situ and non-reproducible, and in combination with electrochemical characterization, the interaction and microstructure change of catalyst layer, membrane and porous transport layer and other key components during operation can be analyzed in detail, which is helpful to understand the degradation mechanism of chemical degradation of the membrane and deactivation of the catalyst.

[0084] The PEM electrolyzer membrane electrode accelerated degradation system of the application innovatively designs a micro PEM electrolyzer, which is much smaller than the size of the common PEM electrolyzer on the market, to adapt to the high-resolution in-situ detection of commercial micro-CT and the key observation of the vulnerable area of the membrane electrode. Compared with the X-ray generated by the synchrotron radiation light source, the commercial micro-CT has the characteristics of moderate energy control, low radiation dose, small sample damage, low thermal effect, etc., can maintain the original properties of the PEM electrolyzer after multiple XCT imaging, and has the advantages of simple operation, fast imaging and easy maintenance.

[0085] The current degradation module of the PEM electrolyzer membrane electrode accelerated degradation system can realize high-frequency direct current square wave cycling in the range of 0A / cm 2 -10A / cm 2 The programmable direct current source can be connected to the microcomputer through the USB communication line, and the PEM electrolyzer current cycle coupled with clean energy such as wind, light and electricity can be edited. Compared with the common current density cycling 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 reduce the test time, and can simulate the intermittent and fluctuating output of wind, light and electricity energy, and provide a more realistic accelerated degradation environment.

[0086] The application innovatively applies the micro PEM electrolyzer and XCT technology to the PEM electrolyzer membrane electrode degradation detection field, and in view of the shortcomings of the existing PEM electrolyzer membrane electrode degradation method, 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 reduction degree of the real PEM electrolyzer chemical degradation environment, and realizes the non-destructive in-situ detection of the PEM electrolyzer membrane electrode degradation by using the in-situ detection system of the PEM electrolyzer membrane electrode accelerated degradation system.

[0087] Although the embodiments and drawings of the application are disclosed for the purpose of illustration, those skilled in the art can understand that various alternatives, changes and modifications are possible without departing from the spirit and scope of the application and the appended claims, therefore, the scope of the application is not limited to the disclosed content of the embodiments and drawings.

Claims

1. A PEM electrolyzer membrane electrode accelerated degradation system, characterized in that: comprising 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 connected with the PEM electrolyzer (24) respectively; The current degradation module comprises a programmable DC power supply (23) and a banana plug to flat test lead (32); the programmable DC power supply (23) is connected to the micro-PEM electrolyzer (24) through the banana plug to flat test lead (32) respectively; The deionized water circulation module comprises a deionized water tank (28), a digital peristaltic pump (27), a PVC hose (33), a variable diameter straight connector (34) and a quick plug straight connector (35); the micro-PEM electrolyzer (24) is connected with one end of the quick plug straight connector (35) through screw thread cooperation, the other end of the quick plug straight connector (35) is connected with a three-way connector through the PVC hose (33), the deionized water tank (28) and the digital peristaltic pump (27) are connected through the PVC hose (33), forming a water circulation; The temperature control module comprises a switching power supply (31), a digital intelligent temperature controller (29), a solid state relay (30), a platinum resistance (26) and high temperature ceramic heating sheets (25) respectively pasted on the left and right sides (18) of the micro-PEM electrolyzer I-shaped structure; the digital intelligent temperature controller (29) and the platinum resistance (26) are connected to form a temperature sensing loop, and the switching power supply (31), the digital intelligent temperature controller (29), the solid state relay (30) and the high temperature ceramic heating sheet (25) are connected to form a heating loop. The micro-PEM electrolytic cell (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 catalyst-coated proton exchange membrane (8), 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). The anode end plate (13), the anode PVC gasket (12), 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 threaded holes (17) at the same position. 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 catalyst-coated proton exchange membrane (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 in turn, positioned by bolts (15), and sealed and fastened 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 upper and lower symmetrical circular through holes (3) and circular through holes (22) as upper and lower gas-liquid inlets and outlets 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 as gas and liquid flow channels (21) from the upper gas-liquid inlet to the lower gas-liquid outlet on the side of the catalyst-coated proton exchange membrane (8), and a convex flow channel ridge is naturally formed between the two square grooves. The anode end plate (13), the anode PVC gasket (12), 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 H-shaped structures with the same width above and below and a relatively narrow middle part. The upper ends of the anode flow field plate (11) and the cathode flow field plate (5) are both extended to form rectangular electrodes. The anode end plate (13) and the cathode end plate (2) are both extended outward on the side away from the catalyst-coated proton exchange membrane (8) to form upper bosses (14) and lower bosses (16) with internally threaded holes. The anode polytetrafluoroethylene gasket (10) and the cathode polytetrafluoroethylene gasket (6) are both provided with rectangular through holes (19) in the middle. The programmable direct current power supply (23) is connected to the upper end extended rectangular electrodes of the anode flow field plate (11) and the cathode flow field plate (5) of the micro-PEM electrolytic cell (24) through banana plug conversion flat mouth test wires (32). The upper bosses (14) and the lower bosses (16) of the anode end plate (13) and the upper bosses (14) and the lower bosses (16) of the cathode end plate (2) of the micro-PEM electrolytic cell (24) are respectively connected to one end of the quick plug straight connector (35) through threaded cooperation.

2. An accelerated degradation method using the PEM electrolytic cell membrane electrode accelerated degradation system of claim 1, characterized in that it comprises the following steps: S1: Run the deionized water circulation module: make the deionized water flow into the PEM electrolytic cell membrane electrode reach 1 ml / min, and make the PEM electrolytic cell membrane electrode fully wet, the specific steps are as follows: S1.1: Inject 50 ml of deionized water into the deionized water tank (28); S1.2: Turn on the digital peristaltic pump (27) power supply and open the digital peristaltic pump (27) switch; S1.3: Adjust the set water flow rate of the digital peristaltic pump (27) to 1 ml / min, and wait for the actual flow rate to stabilize at 1 ml / min before proceeding to the next step; S2: Run the temperature control module to make the PEM electrolytic cell membrane electrode in a constant temperature environment of 90℃, the specific steps are as follows: S2.1: Turn on the digital intelligent temperature controller (29) power supply and open the digital intelligent temperature controller (29) switch; S2.2: Adjust the set temperature of the digital intelligent temperature controller (29) to 90℃, and wait for the actual temperature to stabilize at 90℃ before proceeding to the next step; S3: Run the current degradation module, and apply a current cycle to the PEM electrolytic cell membrane electrode, the specific steps are as follows: S3.1: Turn on the programmable DC power supply (23) and open the programmable DC power supply (23) switch; S3.2: Connect the programmable DC power supply (23) to the microcomputer through the USB communication line; S3.3: Adjust the programmable DC power supply (23) output to 4A / 15s, 0A / 15S constant current cycle in the microcomputer program; The effective area of the PEM electrolytic cell membrane electrode is 0.4*1.0 mm, according to the current density calculation formula: J=I / A Where I is the current size, A is the effective area of the PEM electrolytic cell membrane electrode; The current density cycle applied to the PEM cell membrane electrode is 10 A / cm 2 / 15 s, 0 A / cm 2 / 15 s; S4: The PEM electrolytic cell membrane electrode completes 500 current density cycles, and the PEM electrolytic cell membrane electrode is cooled to room temperature by sequentially closing the current degradation module, the deionized water circulation module, and the temperature control module.

3. An in-situ detection method of an in-situ detection system of an accelerated degradation method using the PEM electrolytic cell membrane electrode accelerated degradation system of claim 2, characterized in that: The in-situ detection system comprises a micro-PEM electrolytic cell, 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 the imaging area; the electrochemical characterization module comprises an electrochemical workstation (39); The in-situ detection method comprises the following steps: S1: The initial state of the PEM electrolytic cell membrane electrode and every 500 times of current density cycle are completed, the PEM electrolytic cell membrane electrode accelerated degradation system is closed, and the micro-PEM electrolytic cell (24) is taken off from the PEM electrolytic cell membrane electrode accelerated degradation system after the PEM electrolytic cell membrane electrode accelerated degradation system is cooled to room temperature. S2: Start the XCT module, use a commercial micro-CT machine to take in-situ pictures 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, after the shooting is completed, use the matching image reconstruction software to obtain a 3D image of the PEM electrolyzer membrane electrode with a resolution of 1.7 μm; S3: Start the electrochemical characterization module, turn on the electrochemical workstation (39) switch, and adjust the electrochemical workstation mode to polarization curve test and electrochemical impedance spectroscopy test in turn, and perform in-situ electrochemical performance test on the PEM electrolyzer membrane electrode that has undergone current density cycling; S4: Repeat S1, S2, S3 until the PEM electrolyzer membrane electrode 3D image shows that the failure condition of the membrane crack area ratio reaching 15% or the membrane thickness thinning by 15%, or the voltage attenuation rate reaching 15%, the membrane electrode is determined to be failed, and the test is terminated; S5: Based on the XCT 3D image, polarization curve and electrochemical impedance spectroscopy of each cycle stage, the degradation of the PEM electrolyzer membrane electrode is compared and analyzed in-situ.

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