A proton exchange membrane electrolyzer comprising a dual-functional porous layer

Abstract

The present invention relates to a proton exchange membrane electrolyzer comprising a dual-function porous layer, which is formed by stacking a plurality of unit electrolyzers and a separator (7), wherein the plurality of unit electrolyzers are separated by the separator (7), and the unit electrolyzers include an anode side component, a membrane electrode (10), and a cathode side component. The anode side component includes a dual-function porous layer (9), and the dual-function porous layer (9) has a double-layer structure, namely a flow field layer (14) and a microporous layer (13), wherein the flow field layer (14) contains gradient pores in the thickness direction, and a flow field is provided on the side away from the microporous layer (13). The microporous layer (13) is close to the membrane electrode (10) and contains uniform micro-nanoscale pores; the cathode side component includes a non-metallic porous layer (11) and a metal support layer (12). Compared with the prior art, the dual-function porous layer (9) of the present invention takes into account the functions of both the diffusion layer and the flow field structure, improves the gas-liquid transmission capacity inside the electrolyzer, increases the volume power density, and effectively improves the performance of the electrolyzer.

Description

Technical Field

[0001] The present invention belongs to the technical field of electrolyzer hydrogen production device equipment, and relates to a proton exchange membrane electrolyzer comprising a dual-functional porous layer. Background Art

[0002] With the advancement of the "dual carbon" goals, hydrogen energy, as a clean energy, has gradually been valued by human society and is hailed as the ultimate energy of the 21st century. At present, hydrogen is produced by three methods, including hydrocarbon reforming, ammonia cracking and water electrolysis, among which water electrolysis is the cleanest method of hydrogen production. Among the many electrolyzer hydrogen production systems, proton exchange membrane (PEM) electrolyzer hydrogen production has many advantages such as high conversion efficiency, high hydrogen purity, low power consumption, and direct storage of high-pressure hydrogen. Therefore, it has huge potential in application scenarios such as the secondary conversion of renewable energy, distributed mobile hydrogen storage, and large-scale industrial hydrogen production, and has been listed as one of the important development directions of energy technology by European and American countries.

[0003] The proton membrane in the PEM electrolyzer divides the cell into an anode side and a cathode side. Deionized water is introduced into the anode side, where the oxygen evolution reaction (OER) occurs to generate oxygen; the hydrogen evolution reaction (HER) occurs at the cathode to generate high-purity hydrogen. Factors affecting the operating efficiency of the electrolyzer include the electrolyzer structure, the proton membrane catalyst layer, the operating temperature, and the pressure. Among them, the internal structure of the electrolyzer directly affects the flow of gas and liquid within the electrolyzer, the heat dissipation within the electrolyzer, and the airtightness within the electrolyzer. Especially when operating at high current density, the rate of oxygen generation on the surface of the electrolyzer catalyst layer increases sharply. If the bubbles cannot be discharged in time, it will hinder the flow of external liquid water into the catalyst layer, affecting the rate of the OER reaction. Therefore, the electrolyzer structure is an important factor affecting the operating efficiency of the electrolyzer.

[0004] After searching the existing technical literature, it was found that Chinese patent CN214937843U discloses a pure water hydrogen production PEM electrolyzer. This patent unitizes the electrolyzer and connects it with a slider, which is conducive to the installation and disassembly of the electrolytic cell. At the same time, it solves the problem of cell separation that may occur during the operation of the electrolyzer, and avoids the problem of reduced electrolysis efficiency caused by this. However, this patent will cause the electrolyzer to be too large and the volume power density to be low, which is not conducive to the application of high power density conditions. Chinese patent CN111206255A discloses a PEM electrolyzer collector structure and its manufacturing process. The patent proposes a structure with three layers of titanium mesh superimposed, including two layers of buffer titanium mesh and a layer of pressure-bearing mesh, which can improve the stability of the electrolyzer structure, reduce the wear on the membrane electrode, and improve work efficiency. However, this patent also causes low volume utilization of the electrolyzer, and high contact resistance caused by multi-layer contact. Chinese patent CN111621806A discloses a special-shaped current collector, a PEM electrolyzer hydrogen production device, and a method for producing hydrogen in an electrolyzer. This patent utilizes a porous sintered plate as a substrate and provides a parallel flow field parallel to the top surface of the substrate. This optimizes the structure of a conventional proton exchange membrane electrolyzer, simplifies the electrolyzer components, reduces costs, and facilitates assembly. However, this patent still fails to effectively control the porosity of the porous titanium plate. Furthermore, at high current densities, the surface of the substrate without flow channels is prone to gas diaphragm phenomenon, resulting in low gas-liquid transmission capacity. This patent fails to effectively address the gas-liquid transmission problem in electrolyzers at high current densities. Summary of the Invention

[0005] The purpose of the present invention is to overcome the defects of the above-mentioned prior art such as low volume power density of the electrolytic cell and insufficient gas-liquid transmission capacity under high current density leading to performance degradation, and to provide a proton exchange membrane electrolyzer comprising a dual-functional porous layer. The present invention improves the gas-liquid transmission capacity inside the electrolytic cell, increases the volume power density, and effectively improves the performance of the electrolytic cell.

[0006] The purpose of the present invention can be achieved by the following technical solutions:

[0007] A proton exchange membrane electrolyzer comprising a bifunctional porous layer is constructed by stacking several unit electrolyzers and separators, and further comprising a pair of end plates, an insulating plate, and a current collecting plate stacked sequentially from the outside inward. The unit electrolyzers are separated by the separators and sandwiched between the pair of current collecting plates. The unit electrolyzers are the key structure of the proton exchange membrane electrolyzer and comprise an anode side assembly, a membrane electrode (CCM), and a cathode side assembly. The components on the anode and cathode sides are assembled in an asymmetric manner centered on the proton exchange membrane. The anode side assembly has high rigidity and comprises a bifunctional porous layer. The bifunctional porous layer is sintered from metal fibers and has a two-layer structure, namely a flow field layer and a microporous layer. The flow field layer has gradient pores in the thickness direction and a flow field is provided on the side away from the microporous layer. The microporous layer is close to the membrane electrode and contains uniform micro-nanoscale pores. The cathode side assembly has low rigidity and comprises a non-metallic porous layer and a metal support layer. The metal support layer has better mechanical strength than the non-metallic porous layer.

[0008] The cathode side of a proton exchange membrane electrolyzer only needs to discharge hydrogen and a small amount of liquid water (which permeates from the anode to the cathode) that emanates from the three-phase interface. Therefore, the cathode-side components have lower mass transfer requirements than the anode-side components. Cathode-side components place greater emphasis on interface contact and component impedance, while cathode-side components utilize a combination of soft and hard contact to ensure both the compression rate of the non-metallic porous layer (improving contact between the catalytic layer and the non-metallic porous layer, increasing reaction sites) and prevent hydrogen channel collapse (after assembly, when the compression rate of the non-metallic porous layer is 20%, the compression rate of the metal support layer is lower, essentially maintaining the original pore structure).

[0009] As a preferred technical solution, the dual-function porous layer is formed by sintering titanium fibers.

[0010] Furthermore, the flow field layer is sintered from metal fibers, and the internal porosity increases gradually along the thickness direction according to the density of the fiber arrangement, with the porosity varying in the range of 30-80%. The porosity of the flow field layer on the side close to the microporous layer is 30-50%.

[0011] As a preferred technical solution, the gradient porosity arrangement can be achieved by the following statement:

[0012] First, a low-porosity metal fiber layer is arranged in a container and sintered at a high temperature in a tubular sintering furnace.

[0013] Second, high-porosity metal fibers are evenly arranged on the sintered low-porosity metal fiber layer matrix and sintered at high temperature. Repeating this step can achieve a gradient porosity arrangement.

[0014] Furthermore, the flow field of the flow field layer is selected from one or more of parallel flow field, serpentine flow field, point flow field and meandering flow field, and the gradient pore fiber structure and the flow field structure together constitute a channel for gas-liquid transmission in the thickness direction, which is used to increase the rate of gas-liquid transmission in the opposite direction.

[0015] Furthermore, the microporous layer is sintered from metal fibers or metal powders, and its thickness accounts for 10-20% of the thickness of the dual-functional porous layer, and its porosity is 30-40%, which is similar to the porosity and pore size of the flow field layer close to the microporous layer, thereby avoiding the aggregation of generated gas and improving the mass transfer capacity.

[0016] As an optional technical solution, the microporous layer is laminated to the side of the flow field layer close to the microporous layer and sintered as a whole to form a dual-functional porous layer.

[0017] Furthermore, the surface of the microporous layer close to the membrane electrode is coated with corrosion-resistant particles and sintered at high temperature. The particles are composed of one or more metals and their oxides to form a dense thin layer, reduce surface roughness, ensure full contact between the bifunctional porous layer and the membrane electrode, and increase chemical reaction sites.

[0018] As a preferred technical solution, the surface of the microporous layer close to the membrane electrode is coated with iridium oxide powder and sintered at high temperature in a sintering furnace.

[0019] Furthermore, the surface of the dual-function porous layer is subjected to anti-corrosion treatment to prevent the performance of the electrolytic cell from degrading due to long-term operation; the entire dual-function porous layer is subjected to hydrophilic treatment, and the entire layer includes an external plane and an internal metal fiber wrapped surface.

[0020] As a preferred technical solution, the dual-functional porous layer is plated with one or more of iridium and platinum on its surface by physical vapor deposition technology or chemical vapor deposition technology, so that the dual-functional porous layer has oxidation corrosion resistance.

[0021] The dual-function porous layer combines the functions of a diffusion layer and a flow field layer, further optimizing these features. First, the flow field layer, leveraging its gradient pore characteristics, increases the gas discharge rate in the thickness direction. Second, the microporous layer, leveraging its micro- and nano-pore characteristics near the membrane electrode, effectively prevents gas accumulation in the plane.

[0022] The advantage of the described bifunctional porous layer lies in its excellent gas-liquid transport and water-gas-intake properties. The gradient porosity arrangement is due, firstly, to the fact that the capillary pressure in the gas-liquid channel decreases with increasing porosity gradient, facilitating rapid gas discharge through the thickness. Second, the microporous layer of the bifunctional porous layer directly adheres to the catalyst layer, reducing the gap between the membrane electrode and the substrate, thereby increasing the capillary pressure in the planar direction. This increased capillary pressure increases the amount of liquid water transported in the planar direction, thereby hindering the lateral transport of precipitated bubbles. This effectively prevents the formation of large-scale gas diaphragms in the plane. Furthermore, the external flow field of the bifunctional porous layer is another key factor in enhancing gas-liquid transport. Liquid water can quickly flow through the bifunctional porous layer through the flow field. When the electrolyzer operates at high current density, the bubbles that precipitate within the cell will aggregate into a plug flow in the flow field and then be rapidly discharged with the water flow. Therefore, the bifunctional porous layer can reduce the impact of mass transfer on polarization.

[0023] Another advantage of the dual-function porous layer is that it integrates flow field features, allowing the separator to replace the bipolar plate component. Bipolar plates are typically about three times thicker than the separator. This significantly reduces the thickness of the electrolyzer and increases its volumetric power density.

[0024] As an optional technical solution, the membrane electrode includes a proton exchange membrane (sulfonic acid polymer) and an anode side catalytic layer and a cathode side catalytic layer coated on the surface of the proton exchange membrane, which play the role of isolating electrons and conducting protons. The anode side catalytic layer is one or more of iridium, iridium dioxide, or a mixture of ruthenium and ruthenium dioxide, and the cathode side catalytic layer is platinum carbon particles.

[0025] Furthermore, the non-metallic porous layer is carbon paper with a porosity of 70-80% and a thickness of 0.25-0.4 mm, providing a channel for hydrogen discharge.

[0026] As an optional technical solution, the surface of the non-metallic porous layer is subjected to a hydrophilic treatment.

[0027] Furthermore, the metal support layer is sintered from metal fibers, has a porosity of 60-80%, an average pore size of 10-20 μm, and a thickness of 0.25-0.4 mm, providing a channel for hydrogen discharge. The surface of the metal support layer is subjected to anti-corrosion treatment to prevent performance degradation caused by the high anode potential of the electrolytic cell. The anti-corrosion treatment is performed using magnetron sputtering technology, physical vapor deposition technology, or chemical vapor deposition technology. The entire metal support layer is hydrophilic, and the entire layer includes an external plane and an internal metal fiber wrapped surface.

[0028] As a preferred technical solution, the metal support layer is formed by sintering micron-grade stainless steel fibers.

[0029] As a preferred technical solution, the metal support layer is plated with one or more of platinum, iridium, ruthenium, tantalum and their oxides on the surface by magnetron sputtering technology, so that the metal support layer has oxidation corrosion resistance.

[0030] As an optional technical solution, the metal support layer in the cathode side assembly is replaced by a dual-functional porous layer.

[0031] As an optional technical solution, the dual-function porous layer in the anode side component is replaced by a metal support layer.

[0032] Furthermore, the separator is a circular metal plate with four through-holes arranged around its perimeter. The through-holes on opposite sides communicate with each other within the electrolyzer and are arranged orthogonally. One set of through-holes on opposite sides serves as a channel for oxygen and liquid water, while the other set of through-holes on opposite sides serves as a channel for hydrogen. The separator isolates the gas flow between the unit electrolyzers and acts as a conductive plate to connect multiple unit electrolyzers in series.

[0033] Furthermore, the anode side component also includes an anode sealing frame, and the cathode side component also includes a cathode sealing frame. The anode sealing frame and the cathode sealing frame are made of polymer materials, the outer contour is consistent with the partition structure, and the inner contour is gap-fitted with the contained multi-layer structure. Four sealing frame through holes are arranged around, and the position and shape of the sealing frame through holes are consistent with the partition through holes. The through holes are connected to form a main pipe, and sealing grooves and sealing gaskets are set on the edge to isolate the main pipe from airtightness. Branch pipes are arranged at the internal corners to connect the main pipe and the inner layer.

[0034] The end plate is provided with a main pipe port, which is mainly responsible for the inflow of liquid and the outflow of gas. The main pipe is connected to the dual-function porous layer, the non-metallic porous layer and the metal support layer, including the orthogonally arranged anode main pipe and cathode main pipe. Liquid water enters from the anode main pipe, passes through the branch pipe on the anode sealing frame, reaches the dual-function porous layer, further fills the flow field and fiber structure, and oxygen evolution reaction occurs at the three-phase interface of the catalytic layer. During the reaction, the amount of gas released increases sharply with the increase of load current density. The released gas will return along the path of liquid water inflow. Under the action of the gradient pore structure, bubbles gradually gather in the flow field and flow out from the anode main pipe port with the liquid water flow. At the same time, the hydrogen evolution reaction occurs in the cathode side catalytic layer. The hydrogen passes through the non-metallic porous layer and the metal support layer, and reaches the cathode main pipe through the branch pipe for discharge.

[0035] The present invention relates to a proton exchange membrane electrolyzer comprising a dual-functional porous layer. The dual-functional porous layer comprises a flow field layer away from the membrane electrode and a microporous layer close to the membrane electrode. The microporous layer provides a uniform micro-nano pore structure, which improves the contact with the catalytic layer. The porosity of the flow field layer gradually changes in the thickness direction, and a flow field is provided on the outside, which is conducive to the rapid discharge of bubbles inside the electrolyzer. The dual-functional porous layer on the anode side takes into account the functions of the diffusion layer and the flow field structure, greatly improving the gas-liquid transmission capacity and volume power density; the metal support layer on the cathode side ensures the compressibility of the non-metallic porous layer and prevents the hydrogen channel from collapsing. The assembly form on both sides of the anode and cathode can make the internal force uniform, which is conducive to the close fit of each layer. The present invention provides an effective solution to the problem of insufficient gas-liquid transmission capacity of the proton exchange membrane electrolyzer at high power density, and can further improve the polarization performance of the proton exchange membrane electrolyzer at high power density.

[0036] The structural features and component features of the proton exchange membrane electrolyzer can also be applied to proton exchange membrane fuel cells and proton exchange membrane reversible regeneration batteries.

[0037] Compared with the prior art, the present invention has the following advantages:

[0038] (1) The asymmetric unit electrolytic cell composed of the unique multi-layer components of the present invention can make the force inside the electrolytic cell uniform, which helps the catalytic layer and the diffusion layer to fit tightly together, so that the chemical reaction can fully occur;

[0039] (2) The unique dual-function porous layer of the present invention improves the discharge rate of generated gas in the thickness direction based on the gradient pore characteristics;

[0040] (3) The unique dual-functional porous layer of the present invention is based on the micro-nano pore characteristics close to the membrane electrode side, which effectively prevents the generated gas from gathering in the planar direction;

[0041] (4) The unique dual-function porous layer of the present invention is based on the characteristics of the outer flow field and utilizes the flow of liquid water to effectively increase the discharge rate of the generated gas. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 Schematic diagram of the overall isometric structure of the proton exchange membrane electrolyzer including the dual-functional porous layer in Example 1 of the present invention;

[0043] Figure 2 This is a schematic diagram of the cross-sectional structure of a unit electrolytic cell in Example 1 of the present invention;

[0044] Figure 3 Schematic diagram of the cross-sectional structure of a proton exchange membrane electrolyzer comprising five unit electrolyzers of the present invention;

[0045] Figure 4 This is a schematic diagram of the isometric structure of the dual-functional porous layer in Example 1 of the present invention;

[0046] Figure 5 Schematic diagram of the cross-sectional structure of the dual-functional porous layer in Example 1 of the present invention;

[0047] Figure 6 This is a schematic diagram of the positive measurement structure of the anode sealing frame in Example 1 of the present invention;

[0048] Figure 7 This is a schematic diagram of the isometric structure of the partition in Example 1 of the present invention;

[0049] Figure 8 This is a schematic diagram of the cross-sectional structure of a unit electrolytic cell in Example 3 of the present invention.

[0050] Description of the marks in the figure:

[0051] 1—bolt, 2—main pipe port, 3—upper end plate, 4—lower end plate, 5—current collecting plate, 6—insulating plate, 7—partition plate, 8—anode sealing frame, 9—dual-function porous layer, 10—membrane electrode, 11—non-metallic porous layer, 12—metal support layer, 13—microporous layer, 14—flow field layer, 15—sealing groove, 16—branch pipe, 17—main pipe, 18—cathode sealing frame. DETAILED DESCRIPTION

[0052] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments. This embodiment is implemented based on the technical solution of the present invention, and provides a detailed implementation method and specific operation process, but the protection scope of the present invention is not limited to the following embodiments.

[0053] Example 1:

[0054] A proton exchange membrane electrolyzer comprising a dual-functional porous layer, such as Figure 1 As shown, it includes a unit electrolytic cell, a separator 7, an upper end plate 3 and a lower end plate 4, and a pair of current collecting plates 5 and an insulating plate 6.

[0055] The electrolytic cell is composed of several unit electrolytic cells and separators 7 stacked together. The dual-function porous layer 9 is the anode side component, and the non-metallic porous layer 11 and the metal support layer 12 are the cathode side components. The unit electrolytic cell is composed of the dual-function porous layer 9, the membrane electrode 10, the non-metallic porous layer 11 and the metal support layer 12 stacked in sequence, and the outer contour shape and size are consistent, such as Figure 2 As shown, the number of stacked components can be increased as needed. The main pipe ports 2 are aligned and the proton exchange membrane electrolyzer installation fixture is used to limit the position, and five unit electrolyzers are stacked in sequence. The five unit electrolyzers are sandwiched between a pair of end plates, insulating plates 6 and current collecting plates 5 stacked in sequence from the outside to the inside to form a complete proton exchange membrane electrolyzer structure, as shown in FIG. Figure 3 shown.

[0056] Dual-function porous layer 9, such as Figure 4 and Figure 5 As shown, it is made of sintered metal fibers. In this embodiment, the preferred material is titanium fiber with a thickness of 1mm. It provides a channel for gas-liquid transmission inside the anode side of the electrolytic cell. This component is divided into two layers. The side close to the membrane electrode 10 is the microporous layer 13. Its thickness accounts for 10-20% of the thickness of the dual-function porous layer, that is, the thickness is 0.1-0.2mm. In this embodiment, the thickness is preferably 0.2mm. The porosity is 30-40%. In this embodiment, the porosity is preferably 30%. The surface of the microporous layer 13 close to the membrane electrode is coated with corrosion-resistant particles. The particles are composed of one or more metals and their oxides. They are sintered at high temperature in a sintering furnace to form a dense thin layer. In this embodiment, iridium oxide is preferred. This can provide a more uniform pore structure, reduce its surface roughness, increase the sites for hydrogen evolution reaction and oxygen evolution reaction, and promote the occurrence of the reaction. The porosity of the microporous layer 13 is controlled at 30%, and its porosity is similar to that of the connection between the flow field layer 14 and the microporous layer 13. Low porosity can reduce the pore size of the porous structure, thereby reducing the gap between the dual-function porous layer 9 and the catalytic layer after assembly. The narrow gap increases the capillary pressure within the channel, pushing liquid water through the channel into the catalytic layer. Conversely, the greater capillary force within the channel accelerates the precipitation of oxygen bubbles. Similarly, the narrow gap between the flow field layer 14 and the catalytic layer 13 can hinder the lateral movement of the precipitated bubbles, thereby preventing the formation of a large gas diaphragm in the planar direction.

[0057] The side of the dual-function porous layer 9 close to the partition 7 is the flow field layer 14, which has a thickness of 0.8 mm and a porosity range of 30-80%. The porosity of the layer closest to the membrane electrode is 30-50%. In this embodiment, the porosity is preferably arranged at 50%, 60%, 70% and 70%, every 0.2 mm, to provide a channel for gas-liquid transmission. This component achieves a gradient porosity arrangement by controlling the fiber porosity, gradually increasing the pore size along the thickness direction. The capillary pressure of the fiber channel will gradually decrease as the porosity gradient increases, which helps to quickly discharge the gas in the thickness direction. In addition, the outside of the flow field layer 14 is provided with flow field features, and the shape of the outer flow field is selected from one or more of a parallel flow field, a serpentine flow field, a point flow field and a meandering flow field. In this embodiment, a serpentine flow field is preferably used, and the flow channel cross-section depth is 0.5 mm and the width is 1 mm. Liquid water can quickly fill the dual-function porous layer 9 through the flow field. When the electrolytic cell operates at a high current density, the bubbles precipitated inside will gather into a plug flow in the flow field and then be quickly discharged with the water flow.

[0058] The two components provided on the cathode side are a non-metallic porous layer 11 and a metal support layer 12. The non-metallic porous layer 11 is carbon paper with a porosity of 70-80%, a hydrophilic surface treatment, a thickness of 0.25-0.4 mm, and in this embodiment, a thickness of 0.25 mm is preferred, providing a channel for hydrogen discharge. The metal support layer 12 is stainless steel felt with a platinum-plated surface, a porosity of 60-80%, and in this embodiment, a porosity of 70-80%, an average pore size of 10-20 μm, a thickness of 0.25-0.4 mm, and in this embodiment, a thickness of 0.4 mm is preferred, providing a channel for hydrogen discharge. On the one hand, the metal support layer 12 can increase the space for gas transmission; on the other hand, under the support of the metal support layer 12, the non-metallic porous layer 11 can fit more closely with the catalytic layer and receive more uniform force.

[0059] The proton exchange membrane is a 0.25mm-thick Nafion ionomer. Anode and cathode catalyst layers are coated on the membrane surface. The anode catalyst layer is iridium dioxide, while the cathode catalyst layer is platinum-carbon particles. After the membrane electrode is fabricated, it is secured by heat-pressing a multi-layer frame. The frame is 0.25mm thick and made of polytetrafluoroethylene (PTFE).

[0060] The end plates are made of aluminum alloy and are 30 mm thick. The upper end plate 3 is provided with a through hole for bolts 1 and threaded holes for the anode and cathode manifolds, while the lower end plate 4 only has a through hole for bolts 1. The two end plates are connected by bolts 1, which control the compression rate of the non-metallic porous layer 11 at 20%. The main pipe port 2 on the upper end plate 3 is primarily responsible for liquid inflow and gas outflow. The main pipe 17 connects the dual-function porous layer 9, the non-metallic porous layer 11, and the metal support layer 12, and includes orthogonally arranged anode and cathode main pipes. Liquid water enters from the anode main pipe, passes through the branch pipe 16 on the anode sealing frame 8, and reaches the dual-function porous layer 9, further filling the flow field and fiber structure, and an oxygen evolution reaction occurs at the three-phase interface of the catalytic layer. During the reaction, the amount of gas released increases sharply with the increase of the load current density. The released gas will return along the path of the liquid water inflow. Due to the effect of the gradient pore structure, bubbles gradually accumulate in the flow field and flow out of the anode main pipe port along with the liquid water flow. At the same time, hydrogen evolution reaction occurs in the cathode side catalytic layer, and hydrogen passes through the non-metallic porous layer 11 and the metal support layer 12, and reaches the cathode main pipe through the branch pipe 16 for discharge.

[0061] The insulating plate 6 is made of epoxy resin, has a cylindrical shape and a thickness of 4 mm. The inner contour of the upper insulating plate has a through hole, which is aligned with the main pipe hole of the end plate. The inner contour of the lower insulating plate has no through hole.

[0062] The current collecting plate 5 is a copper plate, and its shape is similar to that of the insulating plate 6 , except that it is provided with square protruding electrode terminals.

[0063] Partition 7, such as Figure 7The plate shown is a circular metal plate, preferably a stainless steel plate in this embodiment, 0.6 mm thick and gold-plated for corrosion protection. Four through-holes (7) are arranged around the plate, aligned with the main pipe holes in the end plates. Opposite holes, interconnected and arranged orthogonally within the electrolytic cell, serve as channels for hydrogen, oxygen, and liquid water, respectively. Separators 7 isolate the flow of gas and liquid between the individual electrolytic cells; they also serve as electrodes, connecting multiple electrolytic cells in series.

[0064] Anode sealing frame 8, such as Figure 6 As shown, it is a polymer material, preferably polytetrafluoroethylene (PTFE) in the present embodiment, with a thickness of 1mm, which plays a supporting and limiting role. The outer contour is consistent with the partition 7, and the inner contour is a clearance fit with the dual-function porous layer 9. Four sealing frame through holes are arranged around the anode sealing frame 8. The position and shape of the sealing frame through holes must be consistent with the partition through holes. Each through hole is connected to form a main pipe 17. The air tightness of the main pipe 17 is isolated by arranging a sealing groove 15 and a sealing gasket on the anode sealing frame 8. The sealing groove 15 has a cross-sectional width of 5mm and a depth of 0.4mm. The matching sealing gasket adopts a silicone rubber gasket with a rectangular cross-section, with a width of 4mm and a thickness of 0.5mm. At the inner corner, i.e., near the flow channel inlet, a branch pipe 16 is arranged to connect the main pipe 17 and the dual-function porous layer 9, with a cross-sectional width 2 of 0.5mm and a depth of 0.4mm.

[0065] The cathode branch pipe of the cathode sealing frame 18 needs to be connected to the cathode main pipe. Except for the thickness of 0.6mm, the other parts are the same as the anode sealing frame 8.

[0066] Example 2:

[0067] This embodiment is essentially the same as embodiment 1, except that the dual-function porous layer 9 employs a parallel flow field. Parallel flow channels result in lower pressure drop and faster water intake and exhaust, making them more suitable for long-term, high-power operation of proton exchange membrane electrolyzers.

[0068] Example 3:

[0069] This embodiment is basically the same as embodiment 1, except that the unit electrolytic cell is composed of a dual-function porous layer 9, a membrane electrode 10, a non-metallic porous layer 11 and a dual-function porous layer 9 stacked in sequence. Figure 8 As shown, the microporous layer 13 has a porosity of 40%, the proton exchange membrane is 0.4 mm thick, the membrane electrode frame is 0.4 mm thick, and the cathode sealing frame 18 is 1 mm thick. The use of a dual-function porous layer on the cathode side increases gas permeability and facilitates hydrogen diffusion, making it more suitable for the long-term, high-power operation of the proton exchange membrane electrolyzer.

[0070] Example 4:

[0071] This embodiment is essentially the same as Example 1, except that the membrane electrode 10 of the unit electrolyzer is replaced with a membrane electrode specifically designed for a proton exchange membrane fuel cell. The fuel cell catalyst layer comprises platinum carbon particles, with a higher catalyst loading on the cathode side than on the anode side. The structural advantages of the present invention also apply.

[0072] Example 5:

[0073] This embodiment is essentially the same as Example 1, except that the membrane electrode 10 of the unit electrolyzer is replaced with a membrane electrode specifically designed for a proton exchange membrane integrated regenerative fuel cell. In the integrated regenerative fuel cell power generation mode, the anode-side catalytic layer comprises platinum-carbon particles, while the cathode-side catalytic layer comprises iridium oxide and platinum black particles. The structural advantages of the present invention also apply.

[0074] Comparative Example 1:

[0075] This embodiment is basically the same as embodiment 1. The difference is that the flow field layer 14 is close to the catalyst layer, and the dual-function porous layer 9 is installed and placed in the same manner. Figure 2 The structure shown is the opposite, which will increase the contact impedance between the membrane electrode 10 and the dual-functional porous layer 9 and reduce the effective catalytic sites, while being detrimental to gas-liquid transport.

[0076] Comparative Example 2:

[0077] This embodiment is basically the same as embodiment 3. The difference is that the flow field layer 14 is close to the catalyst layer, and the dual-function porous layer 9 is installed and placed in the same manner. Figure 8 The structure shown is the opposite, which will increase the contact impedance between the membrane electrode 10 and the dual-functional porous layer 9 and reduce the effective catalytic sites, while being detrimental to gas-liquid transport.

[0078] The above description of the embodiments is intended to facilitate understanding and use of the invention by those skilled in the art. It will be apparent that those skilled in the art can readily make various modifications to these embodiments and apply the general principles described herein to other embodiments without requiring inventive effort. Therefore, the present invention is not limited to the above-described embodiments. Improvements and modifications made by those skilled in the art based on the disclosure of the present invention, without departing from the scope of the present invention, should be within the scope of protection of the present invention.

Claims

1. A proton exchange membrane electrolyzer comprising a dual-functional porous layer, comprising a plurality of unit electrolyzers and a separator (7) stacked together, wherein the plurality of unit electrolyzers are separated by the separator (7), wherein the unit electrolyzers comprise an anode side assembly, a membrane electrode (10) and a cathode side assembly, and wherein: The anode side component includes a dual-function porous layer (9), which has a double-layer structure, namely a flow field layer (14) and a microporous layer (13), wherein the flow field layer (14) contains gradient pores in the thickness direction, and a flow field is provided on the side away from the microporous layer (13), and the microporous layer (13) is close to the membrane electrode (10) and contains uniform micro-nanoscale pores; the cathode side component includes a non-metallic porous layer (11) and a metal support layer (12), or a non-metallic porous layer (11) and a dual-function porous layer (9); The internal porosity of the flow field layer (14) increases gradually along the thickness direction, and the porosity variation range is 30-80%. The porosity of the side of the flow field layer (14) close to the microporous layer (13) is 30-50%. The porosity and pore size of the microporous layer (13) and the flow field layer (14) on the side close to the microporous layer (13) are similar; The surface of the microporous layer (13) on the side close to the membrane electrode (10) is coated with corrosion-resistant particles, and the particles are composed of one or more metals and their oxides.

2. A proton exchange membrane electrolyzer comprising a dual-functional porous layer according to claim 1, characterized in that: The flow field layer (14) is formed by sintering metal fibers.

3. A proton exchange membrane electrolyzer comprising a dual-functional porous layer according to claim 1 or 2, characterized in that: The flow field of the flow field layer (14) is selected from one or more of a parallel flow field, a serpentine flow field, a point flow field and a meandering flow field.

4. The proton exchange membrane electrolyzer comprising a dual-functional porous layer according to claim 1, characterized in that: The microporous layer (13) is formed by sintering metal fibers or metal powders, and its thickness accounts for 10-20% of the thickness of the dual-function porous layer (9), and its porosity is 30-40%.

5. The proton exchange membrane electrolyzer comprising a dual-functional porous layer according to claim 1, characterized in that: The surface of the dual-functional porous layer (9) is subjected to anti-corrosion treatment.

6. The proton exchange membrane electrolyzer comprising a dual-functional porous layer according to claim 1, characterized in that: The non-metallic porous layer (11) is carbon paper with a porosity of 70-80% and a thickness of 0.25-0.4 mm.

7. The proton exchange membrane electrolyzer comprising a dual-functional porous layer according to claim 1, characterized in that: The metal support layer (12) is formed by sintering metal fibers, has a porosity of 60-80%, an average pore size of 10-20 μm, and a thickness of 0.25-0.4 mm. The surface of the metal support layer (12) is subjected to anti-corrosion treatment.

8. The proton exchange membrane electrolyzer comprising a dual-functional porous layer according to claim 1, characterized in that: The partition (7) is a circular metal plate with four partition (7) through holes arranged around it. The through holes of the opposite side partition (7) are connected inside the electrolytic cell and are arranged orthogonally. One group of the through holes of the opposite side partition (7) is an oxygen and liquid water channel, and the other group of the through holes of the opposite side partition (7) is a hydrogen channel.

9. The proton exchange membrane electrolyzer comprising a dual-functional porous layer according to claim 8, characterized in that: The anode side assembly further comprises an anode sealing frame (8), and the cathode side assembly further comprises a cathode sealing frame (18). The outer contours of the anode sealing frame (8) and the cathode sealing frame (18) are consistent with the structure of the partition (7), and the inner contours are clearance-matched with the multi-layer structure contained therein. Four sealing frame through holes are arranged around the periphery. The position and shape of the sealing frame through holes are consistent with the through holes of the partition (7). The through holes are connected to form a main pipe (17). A sealing groove (15) and a sealing gasket are provided at the edge. Branch pipes (16) are arranged at the internal corners to connect the main pipe (17) and the inner layer.

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