Proton exchange membrane water electrolyzer membrane electrode assembly

Abstract

The exchange membrane, for example, comprises a first layer membrane having a first thickness and a second layer membrane having a thickness less than the first thickness, the second layer membrane contains a catalyst, the catalyst content of the second layer membrane is greater than the catalyst content of the first layer membrane, and the exchange membrane has an interface between the first layer membrane and the second layer membrane. In some embodiments, the membrane electrode assembly (MEA) comprises a first layer membrane without a catalyst, and / or the exchange membrane comprises a bilayer exchange membrane.

Description

Priority claim

[0001] This application claims the benefit of priority to U.S. Provisional Patent Application No. 63 / 144,539, entitled "Proton Exchange Membrane Water Electrolyzer Membrane Electrode Assembly," filed February 2, 2021, which is incorporated herein by reference in its entirety. [Technical field]

[0002] The present disclosure relates generally to proton exchange membrane water electrolyzer membrane electrode assemblies (MEAs), and more particularly to the manufacture of membranes for water electrolyzer membrane electrode assemblies (MEAs). [Background technology]

[0003] The availability of renewable energy has driven substantial investment in water electrolysis technology. It is estimated that the water electrolysis market could grow to 300 GW over the next 20 years, and power-to-gas could become a multi-billion dollar market for on-site electrolyzer systems over the next decade.

[0004] A proton exchange membrane (PEM) electrolysis cell is a device that uses direct current electricity to produce hydrogen and oxygen gases and electrochemically separate water. A PEM cell contains an "active area" where the presence of a catalyst allows a reaction to occur. In an electrolysis cell, water enters the anode and is split into protons, electrons, and oxygen gas. The protons are conducted through the membrane and the electrons pass through an electric circuit. At the cathode, the protons and electrons recombine to form hydrogen gas. The electrolysis half-reaction is shown below: 2H2O→4H + +4e - +O2 4H + +4e - →2H2

[0005] FIG. 1 shows a prior art wet process 10 for forming a wet membrane for a proton exchange membrane water electrolyzer membrane electrode assembly. In the wet process, in block 12, an ionomer membrane (e.g., Nafion N115) is received, and in block 14, the ionomer membrane is boiled for one hour for hydration. In block 16, the hydrated membrane then undergoes a multi-step platinization process for crossover mitigation purposes, which takes a total of about five days. In block 18, after platinization of the membrane, the membrane is then heated to 1000° C. for 1 hour. + It is then returned to the mold, rinsed and boiled in deionized water at block 20. Once the membrane has been treated, it must be kept wet during the cell assembly process.

[0006] Klose et al. developed an 8 mil trilayer membrane using a Pt-containing spray coating to form an interlayer between the NR212 and N115 membranes. C.Klose et al 2018,Membrane Interlayer with Pt Recombination Particles for Reduction of the Anodic Hydrogen Content in PEM Water Electrolysis, J.Electrochem.Soc.165 F1271. Summary of the Invention

[0007] For example, the shortcomings of the prior art are overcome and additional advantages are provided by providing an exchange membrane including a first layer membrane having a first thickness, a second layer membrane having a thickness less than the first thickness, the second layer membrane containing a catalyst, the catalyst content of the second layer membrane being greater than the catalyst content of the first layer membrane, and an exchange membrane having an interface between the first layer membrane and the second layer membrane.

[0008] In some embodiments, a membrane electrode assembly (MEA) having an exchange membrane includes, for example, a first layer membrane having a first thickness, a second layer membrane having a thickness less than the first thickness, the second layer membrane containing a catalyst, the catalyst content of the second layer membrane being greater than the catalyst content of the first layer membrane, the first layer membrane and the second layer membrane defining an exchange membrane having an interface between the first layer membrane and the second layer membrane, an anode electrode disposed on the second layer membrane, and a cathode electrode disposed on the first layer membrane.

[0009] In some embodiments, the first layer membrane comprises a catalyst-free first layer membrane and / or the exchange membrane comprises a bilayer exchange membrane. [Brief description of the drawings]

[0010] The subject matter which is regarded as the present disclosure is particularly pointed out and distinctly claimed in the concluding portion of this specification, however, the disclosure may be best understood by reference to the following detailed description of various embodiments and the accompanying drawings.

[0011] [Figure 1] 1 is a flow chart of a prior art wet processing method for forming a catalyst membrane for use in a membrane electrode assembly.

[0012] [Diagram 2] 1 is a membrane electrode assembly using an exchange membrane according to one embodiment of the present disclosure.

[0013] [Diagram 3] 1 is a flow chart for forming an exchange membrane according to one embodiment of the present disclosure.

[0014] [Figure 4] FIG. 1 is a schematic diagram of a process for forming a layer film having a catalyst on a substrate according to one embodiment of the present disclosure.

[0015] [Diagram 5] FIG. 1 is a schematic diagram of a roll-to-roll process for forming a layer film having a catalyst on a substrate according to one embodiment of the present disclosure.

[0016] [Figure 6] FIG. 2 is a schematic diagram of a roll-to-roll process for forming a bilayer film stack according to one embodiment of the present disclosure.

[0017] [Figure 7] FIG. 1 is a schematic diagram of a roll-to-roll process for forming a membrane electrode assembly using a two-step lamination process, according to one embodiment of the present disclosure.

[0018] [Figure 8] 1 is a flow chart for forming a membrane electrode assembly using a bilayer membrane lamination process according to one embodiment of the present disclosure.

[0019] [Figure 9] 1 is a flow chart for forming a membrane electrode assembly using a one-step lamination process according to one embodiment of the present disclosure.

[0020] [Figure 10] 1 is a flow chart for forming a recombination layer coated anode decal according to one embodiment of the present disclosure.

[0021] [Figure 11] FIG. 1 is a schematic diagram of a roll-to-roll process for forming a membrane electrode assembly using a one-step lamination process with a membrane electrode assembly having a bilayer membrane, according to one embodiment of the present disclosure.

[0022] [Figure 12] 1 is a flow chart for forming a membrane electrode assembly using a one-step lamination process having a bilayer membrane, according to one embodiment of the present disclosure.

[0023] [Figure 13] 1 is a graph of the polarization curves of a conventional wet process and MEAs made from two dry processes.

[0024] [Figure 14] 1 is a prior art graph of theoretical calculations of optimized recombination layer thickness under different hydrogen back pressures.

[0025] [Figure 15] 1 is a prior art pie chart of capital costs for a PEM electrolyzer system.

[0026] [Figure 16] 1 is a graph of prior art PEM electrolyser efficiency as a function of current density, operating temperature and membrane thickness. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0027] The present disclosure relates to exchange membranes and membrane electrode assemblies (MEAs) using such exchange membranes. For example, the exchange membrane may be a bilayer electrolyzer membrane for a water electrolyzer membrane electrode assembly (MEA), whereby a recombination catalyst such as platinum (Pt) is deposited well near the electrode having one side of the exchange membrane structure, for example only one side, preferably the low pressure side of the electrolyzer. It will be understood that the exchange membrane may include a bilayer exchange membrane or only a bilayer membrane with an additional membrane layer. For example, in an electrolyzer with high pressure hydrogen and low pressure oxygen, it is preferred that the platinum (Pt) recombination catalyst is near the oxygen electrode, since hydrogen permeates faster. Similarly, in a high pressure oxygen configuration, it is preferred that the Pt / ionomer layer is closer to the hydrogen (cathode) side of the membrane electrode assembly. Methods for manufacturing exchange membranes and membrane electrode assembly (MEA) structures are also disclosed.

[0028] As will be appreciated from the present specification, the disclosed techniques for forming, for example, bilayer membranes have demonstrated the capabilities of dry processes for PEM electrolyzer MEA fabrication without sacrificing performance compared to wet processing. The dry process can save on the total capital costs of PEM electrolyzer fabrication by replacing the labor-intensive and time-consuming wet membrane platinization process with a simple relaxed layer casting and dry lamination process. In addition to labor costs, the bilayer membrane design also saves on material costs. Instead of inefficiently distributing the recombination catalyst throughout the membrane, the amount of platinum recombination catalyst in the membrane can be substantially reduced by applying the catalyst to a 1.5 mil layer of the membrane close to the anode catalyst layer.

[0029] As described below, in some embodiments, a thin layer of platinum (Pt) nanoparticles can be laminated on top of the Nafion membrane to replace conventional platinum (Pt) doping in the entire membrane. Such a process can reduce the amount of Pt used in the membrane (e.g., about 1 wt.% to about 5% wt.%), but can also improve the durability and reliability of the PEMWE device. Furthermore, by avoiding the wet bonding process, the process can be easier to integrate into a roll-to-roll (R2R) process for MEA fabrication, which can increase efficiency and save labor involved.

[0030] FIG. 2 shows a membrane electrode assembly (MEA) 100 using an exchange membrane 110 according to one embodiment of the present disclosure. For example, the exchange membrane 110 can include a first layer membrane 120, a second layer membrane 140, a cathode electrode 130, and a cathode electrode 150. The first layer membrane 120 has a first thickness, the second layer membrane 140 has a thickness less than the first thickness, and the second layer membrane 140 includes a catalyst content greater than the catalyst content in the first layer membrane 120. The first layer membrane 120, the second layer membrane 140, the cathode electrode 130, and the anode electrode 1510 are formed into a membrane electrode assembly 100 (MEA) having an exchange membrane 110 with an interface 115 between the first layer membrane 120 and the second layer membrane 140. As described below, the exchange membrane may have two different layer membranes and may be formed by the manufacturing process described below or other suitable process. It will be appreciated that the exchange member can have three or more separate layers, with two of the layers providing an interface between layers having different catalyst content, such as a second layer member having less catalyst or on catalyst compared to a first layer membrane having one catalyst or more catalyst content.

[0031] As will be appreciated, the present configuration of a bilayer exchange membrane in an MEA electrolyzer is desirable for high pressure large scale water electrolyzer cells, which may include avoiding the need for a hydrogen pump and / or mitigating H2 crossover to reduce safety hazards. Hydrogen is often purified and / or compressed so that it can be stored for use. Hydrogen pumps have been used for hydrogen purification and / or compression of hydrogen rich gases. Currently, high pressure storage is being sought to improve the energy density of hydrogen fuel. It is more efficient to directly pressurize H2 from the electrolysis process rather than using a downstream mechanical compressor. However, high differential pressures in the electrolyzer cell create problems with H2 crossover, as it increases the chances that H2 will permeate the membrane and combine with O2 in the cathode. One common approach for H2 crossover mitigation is to disperse a recombination catalyst (such as platinum) throughout the membrane. This material helps to catalyze the reaction between the crossover H2 and O2 on the surface of the cathode side of the membrane. However, scaling up the lengthy processing and material costs of the platinum catalyst used in the membranes increases labor and material costs, preventing current manufacturing processes from meeting the supplies, costs and timelines of a 1 MW stack order.

[0032] Referring to Figure 3, Figure 3 shows a method 200 using a film lamination approach according to one embodiment of the present disclosure. In this illustrated embodiment, the method 200 includes, for example, incorporating platinum (Pt) black material into an ionomer (EG Nafion D2021) containing ink to form a uniform dispersion at block 202. In one example, a uniform platinum (Pt) doped ionomer dispersion can include 160 mg of Pt black, 10.1 mg of cerium hydroxide, and 80 g of NAFION D2021 ionomer, which are ball milled in a plastic container using mixing media. The dispersion is ready to be cast after mixing for two days.

[0033] The dispersion is cast into a thin film on a carrier substrate to form a Pt / ionomer layer at block 204. For example, the dispersion can then be coated onto a substrate such as a polyimide (Kapton) film, such as in a roll-to-roll process as described below.

[0034] The Pt / ionomer layer is then laminated to a membrane that does not have platinum (Pt) incorporated therein (e.g., NAFION 212) at 206. For example, the Pt / ionomer laminate decal is then laminated to a NAFION NR212 membrane in a hot press at 320° F. for 3 minutes to form a bilayer membrane approximately 3.5 mils thick.

[0035] At 208, the bilayer membrane is ready for dry lamination to electrodes. For example, a cathode electrode and an anode electrode may then be laminated to the prepared bilayer membrane to form a membrane electrode assembly (MEA). For example, a cathode electrode and an anode electrode may then be laminated to the NAFION NR212 side and the Pt / ionomer layer side, respectively, of the bilayer membrane using techniques similar to the membrane lamination process, for example, in a hot press at 320° F. for 3 minutes.

[0036] 4 diagrammatically illustrates a process 220 for casting a dispersion into a thin film on a carrier substrate to form a Pt / ionomer layer, according to one embodiment of the present disclosure. For example, a deposition device 230 can include a controllable flow rate and a controllable gap such that a deposition device, such as a syringe or extruder, can continuously deposit a slurry layer 232 onto a moving substrate 234. The slurry 320 can include an ionomer with a catalyst, such as platinum (Pt). The slurry can be disposed to have a thickness of 1-1.5 mils, and the substrate can be a polyimide acker film, or a polyimide, such as a 3 mil Kapton substrate.

[0037] FIG. 5 illustrates a roll-to-roll process 250 according to one embodiment of the present disclosure. In this illustrated embodiment, a deposition device 260, such as an injector or extruder, can continuously deposit a slurry catalyst / ionomer layer 265 onto a moving first substrate 275, which is unwound from a roll 270. The slurry 265 can include an ionomer with a catalyst, such as platinum (Pt), and a radical scavenger, such as cerium hydroxide, which can mitigate membrane degradation. The slurry can be disposed to have a thickness of 1-1.5 mils, and the substrate can be a 3 mil Kapton substrate. The slurry can be cured or partially cured by passing it through a drying step, such as passing it through a heater or oven 280. The dried catalyst / ionomer layer 265 and substrate can be wound onto a roll 290.

[0038] FIG. 6 diagrammatically illustrates a process 300 for forming a laminated bilayer exchange membrane according to one embodiment of the present disclosure. As shown in FIG. 6, the ionomer layer with catalyst can be formed in a roll-to-roll process, and the bilayer membrane can be formed in a lamination process. For example, a deposition device 310, such as a syringe or extruder, can continuously deposit a slurry layer 320 onto a moving substrate 330. The slurry 320 can include an ionomer with a catalyst, such as platinum (Pt). The slurry can be disposed to have a thickness of about 1 mil, and the substrate can be a 3 mil Kapton substrate.

[0039] After the slurry is cured or partially cured, such as by passing through an oven dryer, the ionomer layer 320 and substrate 330 may be die cut to form a die cut structure 350 or may be machined to a desired shape or size. For example, the die cut structure 350 may be sized based on the size of the desired membrane electrode assembly (MEA) to be manufactured. In some embodiments, the die cut structure 350 may be sized to a size of 50 cm 2 or 1200cm 2 and the like.

[0040] Die cut second structure 380 may include, for example, a membrane layer 360 without a catalyst, and a second substrate 370. Membrane layer 360 may be a 2 mil NR212 membrane and second substrate 370 may be an NR212 backer, such as a 3 mil Mylar layer. Die cut structure 350 and die cut structure 380 may be laminated together in a hot press.

[0041] FIG. 7 illustrates a roll-to-roll process 400 for forming an MEA, for example having a two-step lamination process, according to one embodiment of the present disclosure.

[0042] As shown in FIG. 7, a deposition device 410, such as an injector or extruder, can continuously deposit a slurry catalyst / ionomer layer 420 onto a moving first substrate 430, which is unwound from a roll 432. The slurry 420 can include an ionomer with a catalyst, such as platinum (Pt), and a radical scavenger, such as cerium hydroxide. The slurry can be disposed to have a thickness of about 1 mil, and the substrate can be a 3 mil Kapton substrate. After the slurry is cured or partially cured, such as by passing through a heater, oven, or dryer 415, a membrane layer 440, e.g., without a catalyst and disposed on a one-sided backer, is unwound from a roll 442 and deposited onto the cured or partially cured slurry layer 420. The membrane layer 440 can be a 2 mil N212 membrane.

[0043] The layers are bonded and passed through a first hot press 460, for example having a first heated roller 462 and a second heated roller 464. The first substrate 430 is removed and wound on a roller 474, and the substrate on the NR212 membrane 440 is removed and wound on a roller 472. The anode electrode 480 is unwound from a roll 482 and deposited on or adjacent to the catalyst layer 420. The cathode electrode 490 is unwound from a roll 492 and deposited on or adjacent to the membrane 440. The anode electrode 480, catalyst layer 420, catalyst-free membrane layer 440, and cathode electrode 490 are passed through a second hot press 466, for example having a first heated roller 467 and a second heated roller 468, to form a laminated MEA.

[0044] 8 illustrates a method 500 of forming a membrane electrode assembly according to one embodiment of the disclosure. In this illustrated embodiment, the method 500 may include, for example, providing a first layer at 510, providing a second catalyst-containing layer at 520, providing an anode electrode at 530, providing a cathode electrode at 540, and forming the first layer, the second catalyst-containing layer, the anode electrode, and the cathode electrode into a membrane electrode assembly (MEA) at 550, where the first and second layers are formed and the catalyst content of the second layer is greater than the catalyst content of the first layer.

[0045] 9 illustrates a method 600 for forming a relaxed layer coated anode according to one embodiment of the present disclosure. This exemplary approach may facilitate the use of only one high temperature lamination step during the manufacture of a membrane electrode assembly (MEA). This approach may simplify the membrane electrode assembly (MEA) manufacturing process and reduce the time of the high temperature lamination process that may cause mechanical and chemical degradation of the membrane, as compared to the methods described and illustrated in FIGS. 4-8.

[0046] In this exemplary embodiment, as shown in FIG. 9, the method 600 includes preparing a platinum (Pt) doped ionomer dispersion in block 602. The preparation can be the same as the platinum (Pt) doped ionomer dispersion prepared in block 202 (FIG. 3) above. In block 604, the as-prepared platinum (Pt) doped ionomer dispersion is then cast onto an anode decal. In this embodiment, the anode decal is the anode catalyst layer + substrate liner. Multiple passes may be required until a film thickness of 1.5 mils is achieved. The 1.5 mil layer has a thickness of about 0.01 to about 0.5 mg (Pt) / cm. 2 In block 606, the relaxed layer coated anode is ready for dry lamination. For example, a commercially available cathode or catalyst layer coated gas diffusion media can then be laminated to a Nafion N212 membrane by hot pressing both at 320° F. for 3 minutes. The relaxed layer coated anode approach may provide additional cost savings over the NAFION ionomer and recombination catalyst since relaxation is applied only to the active area, not the entire membrane area, and a single lamination step is required.

[0047] 10 diagrammatically illustrates a process 700 for forming an anode decal coated with a recombination layer, according to one embodiment of the present disclosure. As shown in FIG. 10, an anode catalyst layer 720 may be formed in a roll-to-roll process. For example, a deposition device 710, such as a syringe or extruder, can continuously deposit the anode catalyst layer 720 onto a moving substrate 730. The deposited anode catalyst layer and substrate can pass through a dryer.

[0048] The ionomer layer with catalyst can be formed in a roll-to-roll process. For example, a deposition device 750, such as an injector or extruder, can continuously deposit a slurry layer 760 onto a moving anode catalyst layer electrode 720 disposed and supported on a substrate 730. The slurry 760 can include an ionomer with a catalyst, such as platinum (Pt), and a radical scavenger, such as cerium hydroxide. The slurry can be disposed to have a thickness of about 1 to 1.5 mils, and the substrate can be 3 mils of ethylene tetrafluoroethylene (ETFE), a fluoroplastic. The deposited ionomer layer with catalyst can be passed through a dryer.

[0049] The constructed structure 770, for example an anode decal coated with a formed recombination layer, may be die cut to a desired size. A membrane layer (not shown) not including a catalyst and a cathode electrode may be placed or otherwise laid down on the structure 700. A single lamination process, for example hot pressing, may be used to form a membrane electrode assembly (MEA). In other embodiments, a membrane may be placed on the structure 770 in a roll-to-roll process. The membrane layer may be a 2 mil N212 membrane.

[0050] FIG. 11 illustrates a roll-to-roll process 800 for forming a membrane electrode assembly (MEA), for example having a one-step lamination process, according to one embodiment of the present disclosure.

[0051] As shown in FIG. 11, a deposition device 810, such as an injector or extruder, can continuously deposit an anode catalyst layer 820 onto a moving substrate 830. The deposited anode catalyst layer and substrate can pass through a dryer 815. A deposition device 850, such as an injector or extruder, can continuously deposit a slurry catalyst layer 860 onto a moving cathode electrode 820 and a first substrate 830 unwound from a roll 832, respectively. The slurry 860 can include an ionomer with a catalyst, such as platinum (Pt), and a radical scavenger, such as cerium hydroxide. The slurry can be disposed to have a thickness of about 1-1.5 mils, and the substrate 830 can be a 3 mil ETFE substrate. The deposited slurry 860 can pass through a dryer 855. After the slurry is cured or partially cured, a membrane layer 840 without catalyst and with a backer or second substrate on one side is unwound from roll 842 and deposited on the cured or partially cured slurry layer 860, and the backer is removed on roll 844. The membrane layer 840 may be a 2 mil N212 membrane and the second substrate or backer layer may be a 3 mil Mylar layer. A cathode electrode 880 is unwound from roll 882 and deposited on or adjacent to the membrane 840. The layers can be bonded and passed through a hot press 865, for example having a first heated roller 861 and a second heated roller 863, to form a laminate structure for the MEA.

[0052] In some embodiments, the dispersion can be cast into a thin film on a carrier substrate to form a Pt / ionomer layer. For example, the dispersion can then be coated onto a substrate, such as a polyimide (Kapton) film, using a doctor blade film applicator. Multiple layers are cast as necessary until a film thickness of, for example, 1.5 mils is achieved.

[0053] 12 illustrates a method 900 of forming a membrane electrode assembly according to one embodiment of the disclosure. In this illustrated embodiment, the method 900 may include, for example, providing a first layer at 910, providing a second catalyst-containing layer at 920, providing an anode electrode at 930, providing a cathode electrode at 940, and forming the first layer, the second catalyst-containing layer, the anode electrode, and the cathode electrode into a membrane electrode assembly (MEA) at 950, where the first and second layers are formed and the catalyst content of the second layer is greater than the catalyst content of the first layer.

[0054] Figure 13 shows the test results of the traditional wet-formed MEA using N115 membrane and the dry-formed membrane electrode assemblies (MEAs) prepared from both approaches with a 3.5 mil thick bilayer membrane. The MEAs using bilayer membranes made from the membrane lamination method were observed to have similar performance compared to the traditional wet process MEAs, demonstrating the feasibility and potential of dry PEM electrolyzer MEAs.

[0055] It will be appreciated that the techniques disclosed herein overcome the problems of the spray coating technique of Klose et al. For example, the spray coating technique of Klose et al. is not easily controlled and is not well suited for large-scale manufacturing. In addition, the spray coating technique is also limited by low Pt utilization in the intermediate Pt interlayer. Hydrogen molecules have a much higher diffusivity compared to oxygen. Under high back pressure, hydrogen moves much faster than oxygen in the membrane, so recombination occurs at the interface between the membrane and the anode catalyst layer.

[0056] The literature provides theoretical calculations of the optimized recombination layer thickness under different hydrogen back pressures. Figure 14 shows the ideal dimensionless position of the recombination interlayer (hydrogen flux is twice the amount of oxygen flux) versus cathode pressure for anode pressures of 1 bar, 6 bar, 10 bar, and 20 bar, and equilibrium pressure conditions. Calculations are for 80 degrees Celsius.

[0057] The higher the hydrogen back pressure, the closer the location of the recombination layer is to the surface of the electrolyzer anode. In the present disclosure, at 40 bar cathode and 3 bar anode conditions, the recombination layer can be within 10% of the total membrane thickness on the anode side. Another advantage of the present disclosure is the flexibility to adjust the thickness of the recombination to better accommodate different hydrogen back pressure operation. The recombination may be located at the membrane / anode interface.

[0058] Figure 15 shows the capital cost breakdown of a prior art PEM electrolyzer system. Colella, WG, James, BD, Moton, JM, Saur, G. and Ramsden, T., 2014, February, Techno-economic analysis of PEM electrolysis for hydrogen production, in Electrolytic hydrogen production workshop, NREL, Golden, Colorado (Vol. 27). As observed, the stack is the major component of the overall capital cost of a PEM electrolyzer system. The membrane electrode assembly (MEA) is one of the major components that accounts for over 25% of the stack cost.

[0059] As will be appreciated from the present disclosure, a fully dry membrane process may be desirable by reducing membrane processing time and labor costs compared to wet membrane processes. In addition, dry membrane processes can maintain the mechanical strength of the membrane while eliminating dimensional changes during membrane processing. Avoiding sacrificing mechanical strength allows for thinner membranes to be used. A separate recombination layer containing uniformly distributed Pt nanoparticles to distribute the recombination catalyst layer only in the area where the H2 / O2 recombination reaction occurs can significantly reduce H2 crossover to reduce safety hazards. Compared to the current state of the art where the entire membrane is platinized, the recombination layer is more efficient and economical by reducing the amount of Pt in the membrane. Furthermore, dry bilayer membranes retain all the advantages of wet membrane fabrication while maintaining the mechanical strength of the membrane, simultaneously reducing labor costs. Additionally, dry processes allow for thinner membranes as mechanical handling improves, and dry-installed membranes expand in the thickness direction. Compared to current state-of-the-art PEM electrolysis with 0.005-0.007 in. (5-7 mil) membranes operating at 70 °C and 3000 mA / cm2, a 0.003 in. (3 mil) membrane at 95 °C can operate at twice the current density, thus halving the CapEx of the electrolyzer stack, as shown in Figure 16. In an expensive electrical environment, current density can be held constant while using 12% less energy at the stack level.

[0060] From this specification, it will be appreciated that the dry processing method of the present disclosure provides advantages over conventional wet processing processes. For example, wet processing is a laborious and time-consuming process that is not suitable for high throughput and multi-MW electrolyzer manufacturing. Once wet, the membrane must be kept wet and bonded. Also, the wet processing of membranes requires significant labor costs in the manufacture of electrolyzers. As discussed above, platinization of membranes using conventional wet processing techniques generally requires long periods of time, which is time-consuming and results in significant labor costs. In addition to the long processing times and high labor costs, the platinization process distributes excess platinum particles indiscriminately throughout the membrane thickness, rather than where it is most effective. Considering the faster diffusion rates of H2 and O2, and the much higher H2 pressure, only Pt particles close to the anode side of the membrane are expected to be active in reducing H2 crossover due to recombination. Thus, particles at other locations are inactive and only add unnecessary costs. Furthermore, the complex wet process also compromises the mechanical strength of the membrane. This is another reason why thicker membranes are preferred in PEMWEs. It will therefore be appreciated from the present disclosure that by replacing conventional wet membrane processes with dry membrane processes using the techniques of the present disclosure as described and illustrated, the material and labour costs associated with MW scale electrolyser manufacturing can be reduced, thus enabling viable penetration and adoption of MW electrolysers in the renewable energy storage market.

[0061] The present disclosure overcomes the shortcomings of Klose et al.'s 8 mil tri-layer membrane, including: 1) the membrane is too thick, dramatically affecting the efficiency of the electrolytic cell; 2) the spraying and lamination process to manufacture the "tri-layer membrane" is time-consuming and not worthy of mass production; and 3) the location of recombination is in the middle of the two membranes, and it is not easy to adjust the location of the layers.

[0062] The advantages of the present disclosure over the 8 mil tri-layer membrane of Klose et al. include: 1) enabling a bi-layer membrane including a 1 mil recombination layer + NR212 membrane for a total thickness of 3 mils in some embodiments, and an efficient electrolyzer; 2) the entire process can be fully automated and performed roll-to-roll suitable for mass production; and 3) the recombination layer of the present disclosure is located on the anode side of the membrane. The thickness of the recombination can be adjusted to accommodate different hydrogen back pressures.

[0063] As can be recognized by those skilled in the art based on the teachings herein, numerous changes and modifications can be made to the above and other embodiments of the present disclosure without departing from the scope of the present disclosure. The components of the MEA disclosed herein, including the accompanying abstract and drawings, can be replaced with alternative components or features, such as those disclosed in another embodiment, that serve the same, equivalent or similar purpose as known to those skilled in the art, to achieve the same, equivalent or similar result and provide a similar function for the intended purpose by such alternative components or features. Furthermore, the MEA can include more or fewer components or features than the embodiments described and illustrated herein. Thus, this detailed description of the presently preferred embodiment should be interpreted as illustrative, as opposed to restrictive, of the present disclosure.

[0064] The terms used herein are for the purpose of describing particular embodiments only and are not intended to limit the disclosure. As used herein, the singular forms "a," "an," and "the" are intended to include the plural unless the context clearly dictates otherwise. It will be further understood that the terms "comprise" (comprise in any form, such as comprises and comprising), "have" (have in any form, such as has and having), "include" (includes and including in any form), and "contain" (contains and containing in any form) are open-ended linking verbs. As a result, a method or apparatus that "comprises," "has," "includes," or "contains" one or more steps or elements has those one or more steps or elements, but is not limited to having only those one or more steps or elements. Similarly, a method step or apparatus element that "comprises," "has," "includes," or "contains" one or more features has those one or more features, but is not limited to having only those one or more features. Furthermore, a device or structure configured in a particular way is configured in at least that way, but may be configured in other ways not recited.

[0065] The present disclosure has been described with reference to preferred embodiments. It will be understood that the embodiments described herein are examples of several possible configurations for providing the same general features, characteristics, and general system operations. Modifications and alterations will occur to others upon reading and understanding the foregoing detailed description. It is intended that the present disclosure be construed to include all such modifications and alterations.

Claims

1. a first layer having a first thickness; a second layer membrane having a thickness less than the first thickness, the second layer membrane containing a catalyst, the catalyst content of the second layer membrane being greater than the catalyst content of the first layer membrane; an exchange membrane having an interface between the first membrane layer and the second membrane layer; An exchange membrane comprising:

2. The exchange membrane of claim 1 , wherein the first layer membrane comprises the first layer membrane without a catalyst.

3. The exchange membrane of claim 1 , wherein the exchange membrane comprises a bilayer exchange membrane.

4. 2. The exchange membrane of claim 1, wherein the first layer membrane comprises the first layer membrane without a catalyst, and the exchange membrane comprises a bilayer exchange membrane.

5. The exchange membrane of claim 1 , wherein the exchange membrane comprises a laminated exchange membrane.

6. The exchange membrane of claim 1 further comprising the exchange membrane disposed on a substrate.

7. The exchange-membrane of claim 1 , wherein the exchange-membrane comprises a roll of exchange-membrane.

8. The exchange membrane of claim 1 , wherein the exchange membrane comprises a laminated exchange membrane disposed on a roll.

9. 2. The exchange membrane of claim 1, wherein the second layer membrane comprises platinum (Pt) and NAFION ionomer.

10. The exchange membrane of claim 1 , wherein the exchange membrane comprises 1% by weight of the catalyst.

11. 2. The exchange membrane of claim 1, wherein the first layer membrane comprises a NAFION membrane and the second layer membrane comprises an ionomer layer membrane having a platinum (Pt) catalyst.

12. 10. The exchange membrane of claim 1, wherein the first layer membrane has a thickness of at least 1.5 mils to 2 mils and the second layer membrane has a thickness of 1 mil to 1.5 mils.

13. a first layer having a first thickness; a second layer membrane having a thickness less than the first thickness, the second layer membrane containing a catalyst, the catalyst content of the second layer membrane being greater than the catalyst content of the first layer membrane; the first and second membrane layers define an exchange membrane having an interface between the first and second membrane layers; an anode electrode disposed on the second layer film; a cathode electrode disposed on the first layer film; A membrane electrode assembly (MEA) having an exchange membrane comprising:

14. 14. The membrane electrode assembly (MEA) of claim 13, wherein the first layer membrane comprises the first layer membrane without a catalyst.

15. 14. The membrane electrode assembly (MEA) of claim 13, wherein the exchange membrane comprises a bilayer exchange membrane.

16. 14. The membrane electrode assembly (MEA) of claim 13, wherein the first layer membrane comprises the first layer membrane without a catalyst and the exchange membrane comprises a bilayer exchange membrane.

17. 14. The membrane electrode assembly (MEA) of claim 13, wherein the exchange membrane comprises a laminated exchange membrane.

18. 14. The membrane electrode assembly (MEA) of claim 13, wherein the second layer membrane comprises platinum (Pt) and NAFION ionomer.

19. 14. The membrane electrode assembly (MEA) of claim 13, wherein said exchange membrane comprises 1% by weight of said catalyst.

20. 14. The membrane electrode assembly (MEA) of claim 13, wherein the first layer membrane comprises a NAFION membrane and the second layer membrane comprises an ionomer layer membrane having a platinum (Pt) catalyst.

21. 14. The membrane electrode assembly (MEA) of claim 13, wherein said first layer membrane has a thickness of at least 1.5 mils to 2 mils and said second layer membrane has a thickness of 1 mil to 1.5 mils.

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