Membrane electrode assembly with graded gas recombination layer

Abstract

The invention relates to a membrane electrode assembly with a graded gas recombination layer. A membrane electrode assembly includes a cathode portion disposed on one end and an anode portion disposed on an opposite end of the cathode portion. The membrane electrode assembly also includes a cathode ionomer layer disposed adjacent the cathode portion and an anode ionomer layer disposed adjacent the anode portion. In addition, the membrane electrode assembly may include one or more support layers disposed between the cathode ionomer layer and the anode ionomer layer. In addition, the anode ionomer layer includes a plurality of gas recombination catalysts in a staged dispersed form such that a portion of the anode ionomer layer disposed closer to the anode portion contains a higher concentration of gas recombination catalyst than a portion of the anode ionomer layer disposed closer to the cathode portion.

Description

Technical Field

[0001] The present disclosure generally relates to membrane electrode assemblies and their use in producing hydrogen in water electrolyzers. Background Art

[0002] The information provided in this section is intended to generally introduce the background of the present disclosure. To the extent that work currently named as inventors is described in this section, and with respect to aspects of the specification that may not have otherwise been identified as prior art at the time of filing, no admission is made, either expressly or by implication, that it is prior art with respect to the present disclosure.

[0003] A membrane electrode assembly (MEA) can be used in an electrolyzer or other energy storage device to produce hydrogen fuel. To facilitate this, the electrolyzer's MEA is configured to use an electric current to split water molecules into hydrogen and oxygen, which can then be stored as a fuel source for other systems. Many MEAs include a gas recombination layer within the membrane to reduce undesirable hydrogen and oxygen gas crossover during operation due to proton permeation through the membrane.

[0004] Current membrane electrode assemblies (MEAs) incorporate a gas reformation catalyst (GRC) uniformly dispersed throughout the GRC layer. However, this distribution of GRC still requires proton migration within the membrane, leading to membrane breakdown over time. Therefore, there is a need for improved GRC layers for MEAs. Summary of the Invention

[0005] In one configuration, a membrane electrode assembly configured to split water molecules into hydrogen and oxygen using an electric current includes a cathode portion disposed at one end. The membrane electrode assembly also includes an anode portion disposed at an end opposite the cathode portion, a cathode ionomer layer disposed adjacent to the cathode portion, and an anode ionomer layer disposed adjacent to the anode portion. Furthermore, a support layer may be disposed between the cathode ionomer layer and the anode ionomer layer. Furthermore, the anode ionomer layer includes a plurality of gas recombination catalysts in a graded dispersion such that a portion of the anode ionomer layer disposed closer to the anode portion contains a higher concentration of the gas recombination catalyst than a portion of the anode ionomer layer disposed closer to the cathode portion.

[0006] The membrane electrode assembly may further include one or more of the following optional features. For example, the gas recombination catalyst may be one or more of particles, fibers, or flakes. Additionally, the gas recombination catalyst may comprise platinum. Alternatively, the gas recombination catalyst may comprise palladium. Additionally, the gas recombination catalyst may comprise a plurality of gas recombination catalysts having different sizes. Additionally, a second support layer may be disposed between the anode ionomer layer and the anode portion. Alternatively, the anode ionomer layer and the anode portion may be directly adjacent to each other such that a portion of the anode ionomer layer and a portion of the anode portion are in contact with each other. Additionally, the membrane electrode assembly may be used to produce an electrolyzer.

[0007] In another configuration, a membrane electrode assembly configured to split water molecules into hydrogen and oxygen using an electric current includes a cathode portion disposed on one end and an anode portion disposed on an opposite end of the cathode portion. The membrane electrode assembly also includes a cathode ionomer layer disposed adjacent to the cathode portion and an anode ionomer layer disposed adjacent to the anode portion. In addition, the electrode assembly may include a support layer disposed between the cathode ionomer layer and the anode ionomer layer. In addition, the anode ionomer layer includes a first portion disposed closer to the anode portion, a second portion disposed closer to the cathode portion, and a third portion disposed between the first portion and the second portion. In addition, the first portion includes a high concentration of a gas recombination catalyst dispersed therein, and the third portion includes a low concentration of a gas recombination catalyst dispersed therein. Typically, the portion closer to the cathode portion has a lower concentration of the gas recombination catalyst.

[0008] The membrane electrode assembly may further include one or more of the following optional features. For example, the second portion or the third portion may not include any gas recombination catalyst dispersed therein. Furthermore, the gas recombination catalyst may be one or more of particles, fibers, or flakes. Furthermore, the gas recombination catalyst may contain platinum. Furthermore, the gas recombination catalyst may be a plurality of gas recombination catalysts having different sizes. Furthermore, the electrolyzer may include a membrane electrode assembly.

[0009] In another configuration, a proton exchange membrane in an electrolyzer includes a cathode ionomer layer disposed on one end and an anode ionomer layer disposed on an opposite end of the cathode ionomer layer. The proton exchange membrane may further include a support layer disposed between the cathode ionomer layer and the anode ionomer layer. Additionally, the anode ionomer layer includes a plurality of gas recombination catalysts in a graded dispersion such that a portion of the anode ionomer layer disposed further from the cathode ionomer layer contains a higher concentration of the gas recombination catalyst than a portion of the anode ionomer layer disposed closer to the cathode ionomer layer.

[0010] The proton exchange membrane may also include one or more of the following optional features. For example, the gas recombination catalyst may comprise platinum or palladium. Furthermore, the gas recombination catalyst may be one or more of particles, fibers, or flakes. Furthermore, the gas recombination catalyst may be a variety of gas recombination catalysts having different sizes.

[0011] The present invention discloses the following solutions:

[0012] Solution 1. A membrane electrode assembly configured to split water molecules into hydrogen and oxygen using an electric current, the membrane electrode assembly comprising:

[0013] a cathode portion disposed on one end;

[0014] an anode portion disposed on opposite ends of the cathode portion; and

[0015] a proton exchange membrane disposed between the cathode portion and the anode portion, the proton exchange membrane comprising:

[0016] a cathode ionomer layer disposed adjacent to the cathode portion;

[0017] an anode ionomer layer disposed adjacent to the anode portion; and

[0018] a support layer disposed between the cathode ionomer layer and the anode ionomer layer, the anode ionomer layer including a plurality of gas recombination catalysts in a graded dispersed form such that a portion of the anode ionomer layer disposed closer to the anode portion contains a higher concentration of the gas recombination catalyst than a portion of the anode ionomer layer disposed closer to the cathode portion.

[0019] Option 2. The membrane electrode assembly according to Option 1, wherein the gas reforming catalyst is one or more of particles, fibers or flakes.

[0020] Option 3. The membrane electrode assembly of Option 1, wherein the gas recombination catalyst comprises platinum.

[0021] Option 4. The membrane electrode assembly of Option 1, wherein the gas recombination catalyst comprises palladium.

[0022] Option 5. The membrane electrode assembly according to Option 1, wherein the gas recombination catalyst is a plurality of gas recombination catalysts having different sizes.

[0023] Option 6. The membrane electrode assembly of Option 1, wherein an ionomer layer free of a gas reforming catalyst is disposed between the anode ionomer layer and the anode portion.

[0024] Option 7. The membrane electrode assembly of Option 1, wherein the anode ionomer layer and the anode portion are directly adjacent to each other such that a portion of the anode ionomer layer and a portion of the anode portion are in contact with each other.

[0025] Option 8. An electrolyzer comprising the membrane electrode assembly of Option 1 and configured to produce hydrogen fuel.

[0026] Option 9. A vehicle comprising hydrogen fuel produced by the electrolyzer described in Option 8.

[0027] 10. A membrane electrode assembly configured to split water molecules into hydrogen and oxygen using an electric current, the membrane electrode assembly comprising:

[0028] a cathode portion disposed on one end;

[0029] an anode portion disposed on opposite ends of the cathode portion; and

[0030] a proton exchange membrane extending between the cathode portion and the anode portion, the proton exchange membrane comprising:

[0031] a cathode ionomer layer disposed adjacent to the cathode portion; and

[0032] an anode ionomer layer disposed adjacent to the anode portion, the anode ionomer layer including a first portion disposed closer to the anode portion, a second portion disposed closer to the cathode portion, and a third portion disposed between the first portion and the second portion, the first portion including a high concentration of a gas recombination catalyst dispersed therein, and the third portion including a low concentration of a gas recombination catalyst dispersed therein.

[0033] Option 11. The membrane electrode assembly of Option 10, wherein the second portion does not include any gas reforming catalyst dispersed therein.

[0034] Option 12. The membrane electrode assembly according to Option 10, wherein the gas reforming catalyst is one or more of particles, fibers or flakes.

[0035] Option 13. The membrane electrode assembly of Option 10, wherein the gas recombination catalyst comprises platinum.

[0036] Option 14. The membrane electrode assembly according to Option 10, wherein the gas recombination catalyst is a plurality of gas recombination catalysts having different sizes.

[0037] Option 15. The membrane electrode assembly of Option 10, wherein the gas recombination catalyst comprises palladium.

[0038] Option 16. An electrolytic cell comprising the membrane electrode assembly described in Option 10.

[0039] Solution 17. A proton exchange membrane comprising:

[0040] a cathode ionomer layer disposed on one end;

[0041] an anode ionomer layer disposed on opposite ends of the cathode ionomer layer; and

[0042] a support layer disposed between the cathode ionomer layer and the anode ionomer layer, the anode ionomer layer comprising a plurality of gas recombination catalysts in a graded dispersed form such that a portion of the anode ionomer layer disposed farther from the cathode ionomer layer contains a higher concentration of the gas recombination catalyst than a portion of the anode ionomer layer disposed closer to the cathode ionomer layer.

[0043] Option 18. A proton exchange membrane according to Option 17, wherein the gas recombination catalyst comprises platinum.

[0044] Option 19. A proton exchange membrane according to Option 17, wherein the gas recombination catalyst is one or more of particles, fibers or flakes.

[0045] Option 20. The proton exchange membrane according to Option 17, wherein the gas recombination catalyst is a plurality of gas recombination catalysts having different sizes. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] The drawings described herein are for illustrative purposes only of selected configurations and are not intended to limit the scope of the present disclosure.

[0047] Figure 1 is a schematic diagram of an electrolyzer including a membrane electrode assembly according to the present disclosure;

[0048] Figure 2 yes Figure 1 A schematic diagram of an example of a membrane electrode assembly used in an electrolyzer;

[0049] Figure 3 is a schematic diagram of another example of a membrane electrode assembly according to the present disclosure;

[0050] Figure 4 is a schematic diagram of yet another example of a membrane electrode assembly according to the present disclosure;

[0051] Figure 5 is a schematic diagram of yet another example of a membrane electrode assembly according to the present disclosure; and

[0052] Figure 6 is a schematic diagram of yet another example of a membrane electrode assembly according to the present disclosure.

[0053] Corresponding reference numerals indicate corresponding parts throughout the drawings. DETAILED DESCRIPTION

[0054] Example configurations will now be described more fully with reference to the accompanying drawings. Example configurations are provided so that this disclosure will be thorough and fully convey the scope of this disclosure to those of ordinary skill in the art. Specific details, such as examples of specific components, devices, and methods, are set forth to provide a comprehensive understanding of the configurations of this disclosure. It will be apparent to those of ordinary skill in the art that specific details need not be employed, that example configurations may be embodied in many different forms, and that the specific details and example configurations should not be construed as limiting the scope of this disclosure.

[0055] The terms used herein are only for the purpose of describing a particular example configuration and are not intended to be limiting. As used herein, the singular articles "a", "an" and "the" may also be intended to include plural forms, unless the context clearly indicates otherwise. The terms "comprise", "include" and "have" are inclusive and therefore specify the presence of features, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, elements, components and / or combinations thereof. The method steps, methods and operations described herein should not be interpreted as necessarily requiring them to be performed in the particular order discussed or shown, unless specifically identified as an execution order. Additional or alternative steps may be adopted.

[0056] When an element or layer is referred to as being "on," "engaged to," "connected to," "attached to," or "coupled to" another element or layer, it can be directly on, engaged, connected, attached, or coupled to the other element or layer, or there may be intervening elements or layers. Conversely, when an element is referred to as being "directly on," "directly engaged to," "directly connected to," "directly attached to," or "directly coupled to" another element or layer, there may be no intervening elements or layers. Other words used to describe the relationship between elements should be interpreted in a similar manner (e.g., "between" vs. "directly between," "adjacent" vs. "directly adjacent," etc.). As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0057] The terms "first", "second", "third" and the like may be used herein to describe various elements, components, regions, layers and / or parts. These elements, components, regions, layers and / or parts should not be limited by these terms. These terms may only be used to distinguish one element, component, region, layer or part from another region, layer or part. Terms such as "first", "second" and other numerical terms do not imply a sequence or order unless the context clearly indicates otherwise. Therefore, without departing from the teachings of the example configuration, the first element, component, region, layer or part discussed below may be referred to as a second element, component, region, layer or part.

[0058] In this application, including the following definitions, the term "module" or the term "controller" may be replaced with the term "circuit". The term "module" may refer to a portion including or including: an application-specific integrated circuit (ASIC); a digital, analog, or mixed analog / digital discrete circuit; a digital, analog, or mixed analog / digital integrated circuit; a combinational logic circuit; a field programmable gate array (FPGA); a processor circuit (shared, dedicated, or group) that executes code; a memory circuit (shared, dedicated, or group) that stores code executed by the processor circuit; other suitable hardware components that provide the functionality described; or a combination of some or all of the above, such as in a system on a chip.

[0059] As used above, the term "code" may include software, firmware, and / or microcode, and may refer to programs, routines, functions, classes, data structures, and / or objects. The term "shared processor circuit" includes a single processor circuit that executes some or all of the code from multiple modules. The term "group processor circuit" includes a processor circuit that, in combination with other processor circuits, executes some or all of the code from one or more modules. The term "shared memory circuit" includes a single memory circuit that stores some or all of the code from multiple modules. The term "group memory circuit" includes a memory circuit that, in combination with other memories, stores some or all of the code from one or more modules. The term "memory" may be a subset of the term "computer-readable medium." The term "computer-readable medium" does not include transient electrical and electromagnetic signals that propagate through the medium, and therefore may be considered to be tangible and non-transitory memory. Non-limiting examples of non-transitory memory include tangible computer-readable media, including non-volatile memory, magnetic storage devices, and optical storage devices.

[0060] The apparatus and methods described herein may be implemented in part or in whole by one or more computer programs executed by one or more processors. The computer programs include processor-executable instructions stored on at least one non-transitory tangible computer-readable medium. The computer programs may also include and / or rely on stored data.

[0061] A software application (i.e., a software resource) may refer to computer software that enables a computing device to perform tasks. In some instances, a software application may be referred to as an "application," "app," or "program." Example applications include, but are not limited to, system diagnostic applications, system management applications, system maintenance applications, word processing applications, spreadsheet applications, messaging applications, media streaming applications, social networking applications, and gaming applications.

[0062] Non-transitory memory can be a physical device used to temporarily or permanently store programs (e.g., instruction sequences) or data (e.g., program state information) for use by a computing device. Non-transitory memory can be volatile and / or non-volatile addressable semiconductor memory. Examples of non-volatile memory include, but are not limited to, flash memory and read-only memory (ROM) / programmable read-only memory (PROM) / erasable programmable read-only memory (EPROM) / electrically erasable programmable read-only memory (EEPROM) (e.g., commonly used for firmware, such as bootloaders). Examples of volatile memory include, but are not limited to, random access memory (RAM), dynamic random access memory (DRAM), static random access memory (SRAM), phase change memory (PCM), and magnetic disk or tape.

[0063] These computer programs (also referred to as programs, software, software applications, or code) include machine instructions for a programmable processor and may be implemented in high-level procedural and / or object-oriented programming languages and / or assembly / machine languages. As used herein, the terms "machine-readable medium" and "computer-readable medium" refer to any computer program product, non-transitory computer-readable medium, device, and / or apparatus (e.g., a disk, optical disk, memory, programmable logic device (PLD)) for providing machine instructions and / or data to a programmable processor, including machine-readable media that receives machine instructions as a machine-readable signal. The term "machine-readable signal" refers to any signal used to provide machine instructions and / or data to a programmable processor.

[0064] Various implementations of the systems and techniques described herein can be implemented in digital electronic and / or optical circuitry, integrated circuits, specially designed ASICs (application-specific integrated circuits), computer hardware, firmware, software, and / or combinations thereof. These various implementations can include implementation in one or more computer programs executable and / or interpretable on a programmable system including at least one programmable processor, which can be special purpose or general purpose, coupled to receive data and instructions from it and to transmit data and instructions to a storage system, at least one input device, and at least one output device.

[0065] The processes and logic flows described in this specification can be performed by one or more programmable processors (also known as data processing hardware) executing one or more computer programs to perform functions by operating on input data and generating output. Processes and logic flows can also be performed by special-purpose logic circuitry, such as an FPGA (field programmable gate array) or an ASIC (application-specific integrated circuit). Processors suitable for executing computer programs include, by way of example, general-purpose and special-purpose microprocessors, as well as any one or more processors of any type of digital computer. Typically, a processor will receive instructions and data from read-only memory or random access memory, or both. The essential elements of a computer are a processor for executing instructions and one or more memory devices for storing instructions and data. Generally, a computer will also include, or be operatively coupled to receive data from or transfer data to, or both, one or more mass storage devices for storing data, such as magnetic, magneto-optical, or optical disks. However, a computer need not have such devices. Computer-readable media suitable for storing computer program instructions and data include all forms of non-volatile memory, media, and storage devices, including, for example, semiconductor memory devices such as EPROM, EEPROM, and flash memory devices; magnetic disks, such as internal hard drives or removable disks; magneto-optical disks; and CD ROM and DVD-ROM disks. The processor and the memory can be supplemented by, or include, special purpose logic circuitry.

[0066] To provide for interaction with a user, one or more aspects of the present disclosure may be implemented on a computer having a display device for displaying information (e.g., a CRT (cathode ray tube), an LCD (liquid crystal display) monitor, or a touch screen) and optionally providing the user with a keyboard and pointing device, such as a mouse or trackball, through which the user can provide input to the computer. Other types of devices may also be used to provide for interaction with a user; for example, feedback provided to the user may be any form of sensory feedback, such as visual feedback, auditory feedback, or tactile feedback; and input from the user may be received in any form, including sound, voice, or tactile input. In addition, a computer may interact with a user by sending documents to and receiving documents from a device used by the user. For example, by sending a web page to a web browser on a user's client device in response to a request received from the web browser.

[0067] Reference Figure 1-6 , discloses a membrane electrode assembly 100. The membrane electrode assembly 100 is configured to split water molecules into hydrogen and oxygen using an electric current. In addition, the membrane electrode assembly 100 may include an electrolyzer 12, such as Figure 1As shown. In addition, the electrolyzer 12 may include a water tank 16, a hydrogen tank 17, and a power source 18 connected to the membrane electrode assembly 100. More specifically, the membrane electrode assembly 100 uses electricity from the power source 18 to decompose water from the water tank 16 into oxygen and hydrogen, and then stores the hydrogen in the hydrogen tank 17. In addition, the stored hydrogen can then be used for other applications that use hydrogen fuel, such as a fuel cell electric vehicle 10, such as Figure 1 shown.

[0068] like Figure 2 As shown, the membrane electrode assembly 100 includes a cathode portion 20 disposed at one end and an anode portion 22 disposed at the opposite end of the cathode portion 20. The cathode portion 20 includes a negatively charged porous electrode, through which electrons enter the membrane electrode assembly 100 and a hydrogen evolution reaction (i.e., a chemical reaction that produces hydrogen) occurs within the porous electrode. Additionally, the anode portion 22 includes a positively charged porous electrode, through which protons enter the membrane electrode assembly 100 and electrons exit the membrane electrode assembly 100, and an oxygen evolution reaction (i.e., a chemical reaction that produces oxygen) occurs within the porous electrode.

[0069] Still refer to Figure 2 In the example shown, the proton exchange membrane 24 is disposed between the cathode portion 20 and the anode portion 22. Typically, the proton exchange membrane 24 may comprise a fluoropolymer proton-permeable electrical insulator barrier. Alternatively, the proton exchange membrane 24 may be a hydrocarbon proton-permeable electrical insulator barrier. In addition, the proton exchange membrane 24 serves as a conductor for the protons generated at the anode portion 22 to transport the protons as reactants of the hydrogen evolution reaction to the cathode portion 20. In addition, the proton exchange membrane 24 may also serve as an insulator for electrons to flow through an external circuit. In addition, the proton exchange membrane 24 may comprise Nafion, such as Nafion XL, 112, 115, 117, or 1110.

[0070] In addition, if Figure 2 As shown, the proton exchange membrane 24 includes a plurality of layers disposed between the cathode portion 20 and the anode portion 22. For example, the proton exchange membrane 24 may include a cathode ionomer layer 26 and an anode ionomer layer 28. In addition, if desired, the proton exchange membrane may include a support layer 30. The cathode ionomer layer 26 functions to conduct protons through the cathode ionomer layer 26. In addition, the cathode ionomer layer 26 may include an ionomer nanofiber scaffold, including a polymer material composed of a thermoplastic resin that is stabilized by ionic crosslinking. In addition, the cathode ionomer layer 26 is disposed adjacent to the cathode portion 20. Figure 2 In the example shown, cathode ionomer layer 26 is disposed directly adjacent cathode portion 20 such that a portion of cathode ionomer layer 26 is in contact with cathode portion 20. However, it is contemplated that another layer or other portion may be disposed between cathode portion 20 and cathode ionomer layer 26.

[0071] like Figure 2 As shown, the proton exchange membrane 24 may further include a support layer 30 disposed between the cathode ionomer layer 26 and the anode ionomer layer 28. If the support layer 30 is included in the proton exchange membrane 24, the proton exchange membrane 24 may be referred to as a reconstituted membrane. The function of the support layer 30 is to provide additional mechanical strength to the proton exchange membrane 24. If the proton exchange membrane 24 itself has high mechanical strength, the support layer 30 may not be required. On the other hand, if necessary, multiple support layers 30 may be utilized to further strengthen the proton exchange membrane 24. In addition, the support layer 30 may be proton conductive and may include a material similar to the cathode ionomer layer 26. More specifically, the support layer 30 may include an ionomer embedded in a porous reinforcement layer. In addition, the support layer 30 may also include an ionomer nanofiber scaffold, including a polymer material composed of a thermoplastic resin stabilized by ionic crosslinking.

[0072] In addition, the main function of the anode ionomer layer 28 is to conduct protons. In addition, the anode ionomer layer 28 may include an ionomer nanofiber scaffold, including a polymer material composed of a thermoplastic resin stabilized by ionic crosslinking. Figure 2 As shown, the anode ionomer layer 28 is disposed adjacent to the anode portion 22. In the example shown, the anode ionomer layer 28 is disposed directly adjacent to the anode portion 22 such that a portion of the anode ionomer layer 28 is in contact with the anode portion 22. However, it is also contemplated that a support layer 30 or other layer may be disposed between the anode portion 22 and the anode ionomer layer 28, as described in more detail below.

[0073] Additionally, the anode ionomer layer 28 includes a plurality of gas recombination catalysts 32 configured to recombine stoichiometric amounts of hydrogen and oxygen and convert them into water. The gas recombination catalysts 32 may be disposed in a membrane positioned on top of the anode ionomer layer 28 as a gas recombination layer, or the gas recombination catalysts 32 may be otherwise disposed on or within the anode ionomer layer 28. Furthermore, the anode ionomer layer 28 may contain additives, such as cerium compounds and / or manganese for chemical stability. Furthermore, it is contemplated that additives such as cerium compounds and / or manganese may be present in any layer of the proton exchange membrane 24. Furthermore, the gas recombination catalysts 32 may include, but are not limited to, platinum and / or palladium. Furthermore, the gas recombination catalysts 32 may include a support material, such as carbon or silica. Furthermore, the gas recombination catalysts 32 may be in the form of one or more of particles, fibers, or flakes. Furthermore, the gas recombination catalysts 32 may include particles, fibers, or flakes of varying sizes.

[0074] Refer again Figure 2In the illustrated example, the gas recombination catalyst 32 is dispersed in the anode ionomer layer 28 in a graded manner such that a portion of the anode ionomer layer 28 positioned closer to the anode portion 22 includes a higher concentration of the gas recombination catalyst 32 than a portion of the anode ionomer layer 28 positioned closer to the cathode portion 20. For example, a portion of the anode ionomer layer 28 positioned closer to the anode 22 than the support layer 30 or the cathode ionomer layer 26 may include approximately 60-95% of the total amount of the gas recombination catalyst 32 in the proton exchange membrane 24. In another example, a portion of the anode ionomer layer 28 positioned closer to the anode 22 may include approximately 70-90% of the total amount of the gas recombination catalyst 32 in the proton exchange membrane 24. In yet another example, a portion of the anode ionomer layer 28 positioned closer to the anode 22 may include approximately 80-90% of the total amount of the gas recombination catalyst 32 in the proton exchange membrane 24.

[0075] Now refer to Figure 3 and Figure 4 The example shown is similar to Figure 2 In the example shown, the gas recombination catalyst 32 is dispersed in the anode ionomer layer 28 in a graded manner such that a portion of the anode ionomer layer 28 disposed closer to the anode portion 22 includes a higher concentration of the gas recombination catalyst 32 than a portion of the anode ionomer layer 28 disposed closer to the cathode portion 20. More specifically, Figure 3 and Figure 4 In the example shown, the anode ionomer layer 28 may include a first portion 29 disposed closer to the anode portion 22, a second portion 31 disposed closer to the cathode portion 20, and a third portion 33 disposed between the first portion 29 and the second portion. In this configuration, the first portion 29 includes a high concentration of a gas recombination catalyst 32 dispersed therein, and the third portion 33 includes a low concentration of a gas recombination catalyst 32 dispersed therein. Figure 3 In the example shown, the second portion 31 includes a gas reforming catalyst 32 at a concentration level that is generally lower than the concentration level of the gas reforming catalyst 32 in the third portion 33. Alternatively, Figure 4 In the example shown, the second portion 31 does not include any gas reforming catalyst 32 dispersed therein.

[0076] Now refer to Figure 5 In the example shown, a thin ionomer layer 34 is disposed between the anode ionomer layer 28 and the anode portion 22. When present, the thin ionomer layer 34 is configured to prevent the gas recombination catalyst 32 from being exposed to the high electrical potential of the anode portion 22, thereby reducing the risk of catalyst degradation. Additionally or alternatively, the thin ionomer layer 34 can be configured to provide mechanical support to the membrane 24, similar to the support layer 30 described above.

[0077] Now refer to Figure 6In the example shown, the membrane electrode assembly 100 may not include the support layer 30 located between the anode ionomer layer 28 and the cathode ionomer layer 26. In other words, Figure 6 In the example shown, the anode ionomer layer 28 and the cathode ionomer layer 26 are directly adjacent to each other. However, as described above, the anode ionomer layer 28 still includes the gas recombination catalyst 32 in a graded dispersion such that a portion of the anode ionomer layer 28 positioned closer to the anode portion 22 includes a higher concentration of the gas recombination catalyst 32 than a portion of the anode ionomer layer 28 positioned further from the anode portion 22.

[0078] The gas recombination catalyst 32 is dispersed in the anode ionomer layer 28 in a graded manner, such that a portion of the anode ionomer layer 28 disposed closer to the anode portion 22 includes a higher concentration of the gas recombination catalyst 32 than a portion of the anode ionomer layer 28 disposed closer to the cathode portion 20, thereby ensuring high utilization of the gas recombination catalyst 32 and significantly reducing gas crossover. Consequently, the resulting membrane electrode assembly 100 is more efficient and safer to operate than previous membrane electrode assemblies.

[0079] A variety of implementations have been described. However, it will be appreciated that various modifications can be made without departing from the spirit and scope of this disclosure. Therefore, other implementations are within the scope of the appended claims.

[0080] The foregoing description is provided for the purpose of illustration and description. It is not intended to be exhaustive or to limit the present disclosure. Individual elements or features of a particular configuration are generally not limited to that particular configuration, but are interchangeable where applicable and can be used in a selected configuration, even if not specifically shown or described. The same situation is also possible in many variations. Such variations should not be considered a departure from the present disclosure, and all such modifications are intended to be included within the scope of the present disclosure.

Claims

1. A membrane electrode assembly configured to split water molecules into hydrogen and oxygen using an electric current, the membrane electrode assembly comprising: a cathode portion disposed on one end; an anode portion disposed on opposite ends of the cathode portion; and a proton exchange membrane disposed between the cathode portion and the anode portion, the proton exchange membrane comprising: a cathode ionomer layer disposed adjacent to the cathode portion; an anode ionomer layer disposed adjacent to the anode portion; and a support layer disposed between the cathode ionomer layer and the anode ionomer layer, the anode ionomer layer including a plurality of gas recombination catalysts in a graded dispersed form such that a portion of the anode ionomer layer disposed closer to the anode portion contains a higher concentration of the gas recombination catalyst than a portion of the anode ionomer layer disposed closer to the cathode portion. 2 . The membrane electrode assembly according to claim 1 , wherein the gas reforming catalyst is one or more of particles, fibers, or flakes.

3. The membrane electrode assembly of claim 1, wherein the gas recombination catalyst comprises platinum.

4. The membrane electrode assembly of claim 1, wherein the gas recombination catalyst comprises palladium. The membrane electrode assembly according to claim 1 , wherein the gas recombination catalyst is a plurality of gas recombination catalysts having different sizes.

6. The membrane electrode assembly of claim 1, wherein an ionomer layer free of a gas reforming catalyst is disposed between the anode ionomer layer and the anode portion. 7 . The membrane electrode assembly of claim 1 , wherein the anode ionomer layer and the anode portion are directly adjacent to each other such that a portion of the anode ionomer layer and a portion of the anode portion are in contact with each other.

8. The membrane electrode assembly of claim 1, wherein the proton exchange membrane comprises a thin ionomer layer disposed between the anode ionomer layer and the anode portion.

9. An electrolyzer comprising the membrane electrode assembly of claim 1 and configured to produce hydrogen fuel.

10. A vehicle comprising hydrogen fuel produced by the electrolyzer of claim 8.

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