MULTI-LAYER POROUS TRANSPORT LAYER FOR A MEMBRANE ELECTRODE ASSEMBLY AND METHOD OF MANUFATURING THE SAME

Description

INTRODUCTION

The information provided in this section is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.

The present disclosure relates generally to a membrane electrode assembly and, more particularly, to a porous transport layer.

Electrolyzers are devices that perform electrolysis, which is the process of using electricity to split water into oxygen and hydrogen, which may be used as fuel in vehicles, such as automobiles. Electrolyzers consist of an anode and a cathode separated by an electrolyte. Electrolyzers may include a membrane electrode assembly (MEA), which helps produce the electrochemical reaction needed to split water and separate product hydrogen from product oxygen. On the anode side of the MEA, water is electrochemically oxidized into oxygen and proton. The proton diffuses through the membrane and is electrochemically reduced to hydrogen on the cathode side. Catalysts on each side enable reactions and the membrane allows protons to pass through while keeping the gases separate. In this way, the correct level of voltage and current must be applied to the cell to enable gas production. Additionally, porous transport layers (PTLs) on each side help remove gas from the electrolyzer and provide good electrical conductivity for effective electron conduction. Performance and durability of MEAs can be improved by optimizing the design and/or structure of existing PTLs and these shortcomings are addressed by one or more aspects of the present disclosure.

SUMMARY

In one configuration, a multi-layer porous transport layer (PTL) is provided and includes a first layer including a first surface and a second surface opposite the first surface, the first layer being made of one or more first particles, and a second layer including a first surface and a second surface opposite the first surface, the second surface of the second layer being coupled to the first surface of the first layer, the second layer being made of one or more second particles.

The multi-layer PTL may include one or more of the following optional aspects. For example, the one or more second particles are smaller in diameter than the one or more first particles. The one or more first particles and the one or more second particles are made of titanium.

According to at least one aspect, the multi-layer PTL includes a protrusion barrier arranged between the first surface of the second layer and the second surface of the first layer. The protrusion barrier can include both the one or more first particles and the one or more second particles. The one or more first particles can be interlocked with the one or more second particles.

According to another aspect, the first layer includes a first thickness and the second layer includes a second thickness, the first thickness being greater than the second thickness. The first thickness can be between 100 micrometers (μm) and 500 μm and the second thickness can be between 10 μm and 100 μm.

According to at least one example, some of the one or more second particles are embedded in between some of the one or more first particles.

According to another example, the second layer has a lower surface roughness than the first layer.

In another configuration, a proton exchange membrane (PEM) electrolyzer for generating hydrogen for use as fuel in a vehicle is provided. The PEM electrolyzer includes a first distribution plate and a second distribution plate spaced from the first distribution plate, a membrane arranged between the first distribution plate and the second distribution plate, a cathode compartment arranged between the second distribution plate and the membrane, and an anode compartment arranged between the first distribution plate and the membrane. The anode compartment including an anode catalyst layer arranged adjacent to the membrane and a multi-layer porous transport layer (PTL) arranged between the anode catalyst layer and the first distribution plate. The multi-layer PTL including a first layer being made of one or more first particles and a second layer being made of one or more second particles, the one or more second particles being fused with some of the one or more first particles.

The PEM electrolyzer may include one or more of the following optional aspects. For example, the one or more second particles are smaller in diameter than the one or more first particles. The one or more first particles can have a diameter between 50 micrometers (μm) and 100 μm and the one or more second particles can have a diameter between 1 μm and 45 μm.

According to at least one aspect, the multi-layer PTL further includes a protrusion barrier including some of the one or more first particles and some of the one or more second particles. Some of the one or more second particles can be embedded in between some of the one or more first particles.

According to another aspect, the second layer has a lower surface roughness than the first layer.

According to at least one example, the multi-layer PTL has an arithmetic mean height (Ra) of between 3.0 μm and 6 μm, the second layer being configured to make substantial contact with the anode catalyst layer.

According to yet another configuration, a method of manufacturing a multi-layer porous transport layer (PTL) is provided and includes providing a first layer having one or more first particles, applying a slurry having one or more second particles onto the first layer, drying the slurry on the first layer, and fusing the slurry to the first layer so that at least some of the one or more second particles fuse to the one or more first particles.

The method may include one or more of the following optional aspects or steps. For example, applying the slurry having the one or more second particles onto the first layer further includes mixing the one or more second particles with water, solvents, and binders.

According to another aspect, fusing the slurry to the first layer further includes sintering the slurry and the first layer at a temperature greater than 600 degrees Celsius (° C.) and less than 1400° C.

BRIEF DESCRIPTION OF THE DRAWINGS

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

FIG. 1 is a front perspective view of a vehicle according to principles of the present disclosure;

FIG. 2 is a side view schematic of a membrane electrode assembly (MEA) according to the principles of the present disclosure;

FIG. 3 is a close-up side view of a portion of the MEA of FIG. 2;

FIG. 4 is a graph comparing performance of a single porous transport layer (PTL) versus a multi-layer PTL according to the principles of the present disclosure; and

FIG. 5 is a flow diagram of a method of manufacturing a multi-layer PTL according to the principles of the present disclosure.

Corresponding reference numerals indicate corresponding parts throughout the drawings.

DETAILED DESCRIPTION

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 will fully convey the scope of the disclosure to those of ordinary skill in the art. Specific details are set forth such as examples of specific components, devices, and methods, to provide a thorough understanding of configurations of the present 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 the example configurations should not be construed to limit the scope of the disclosure.

The terminology used herein is for the purpose of describing particular exemplary configurations only and is not intended to be limiting. As used herein, the singular articles “a,” “an,” and “the” may be intended to include the plural forms as well, unless the context clearly indicates otherwise. The terms “comprises,” “comprising,” “including,” and “having,” are inclusive and therefore specify the presence of features, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, steps, operations, elements, components, and/or groups thereof. The method steps, processes, and operations described herein are not to be construed as necessarily requiring their performance in the particular order discussed or illustrated, unless specifically identified as an order of performance. Additional or alternative steps may be employed.

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 may be directly on, engaged, connected, attached, or coupled to the other element or layer, or intervening elements or layers may be present. In contrast, 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 present. Other words used to describe the relationship between elements should be interpreted in a like fashion (e.g., “between” versus “directly between,” “adjacent” versus “directly adjacent,” etc.). As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items.

The terms “first,” “second,” “third,” etc. may be used herein to describe various elements, components, regions, layers and/or sections. These elements, components, regions, layers and/or sections should not be limited by these terms. These terms may be only used to distinguish one element, component, region, layer or section from another region, layer or section. Terms such as “first,” “second,” and other numerical terms do not imply a sequence or order unless clearly indicated by the context. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the example configurations.

In this application, including the definitions below, the term “module” may be replaced with the term “circuit.” The term “module” may refer to, be part of, or include 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 (shared, dedicated, or group) that executes code; memory (shared, dedicated, or group) that stores code executed by a processor; other suitable hardware components that provide the described functionality; or a combination of some or all of the above, such as in a system-on-chip.

The term “code,” as used above, may include software, firmware, and/or microcode, and may refer to programs, routines, functions, classes, and/or objects. The term “shared processor” encompasses a single processor that executes some or all code from multiple modules. The term “group processor” encompasses a processor that, in combination with additional processors, executes some or all code from one or more modules. The term “shared memory” encompasses a single memory that stores some or all code from multiple modules. The term “group memory” encompasses a memory that, in combination with additional memories, stores some or all 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 encompass transitory electrical and electromagnetic signals propagating through a medium, and may therefore be considered tangible and non-transitory memory. Non-limiting examples of a non-transitory memory include a tangible computer readable medium including a nonvolatile memory, magnetic storage, and optical storage.

The apparatuses and methods described in this application may be partially or fully implemented by one or more computer programs executed by one or more processors. The computer programs include processor-executable instructions that are stored on at least one non-transitory tangible computer readable medium. The computer programs may also include and/or rely on stored data.

A software application (i.e., a software resource) may refer to computer software that causes a computing device to perform a task. In some examples, a software application may be referred to as an “application,” an “app,” or a “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.

The non-transitory memory may be physical devices used to store programs (e.g., sequences of instructions) or data (e.g., program state information) on a temporary or permanent basis for use by a computing device. The non-transitory memory may 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)/electronically erasable programmable read-only memory (EEPROM) (e.g., typically used for firmware, such as boot programs). 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) as well as disks or tapes.

These computer programs (also known as programs, software, software applications or code) include machine instructions for a programmable processor, and can be implemented in a high-level procedural and/or object-oriented programming language, and/or in assembly/machine language. As used herein, the terms “machine-readable medium” and “computer-readable medium” refer to any computer program product, non-transitory computer readable medium, apparatus and/or device (e.g., magnetic discs, optical disks, memory, Programmable Logic Devices (PLDs)) used to provide machine instructions and/or data to a programmable processor, including a machine-readable medium 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.

Various implementations of the systems and techniques described herein can be realized in digital electronic and/or optical circuitry, integrated circuitry, 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 that are executable and/or interpretable on a programmable system including at least one programmable processor, which may be special or general purpose, coupled to receive data and instructions from, and to transmit data and instructions to, a storage system, at least one input device, and at least one output device.

The processes and logic flows described in this specification can be performed by one or more programmable processors, also referred to as data processing hardware, executing one or more computer programs to perform functions by operating on input data and generating output. The processes and logic flows can also be performed by special purpose logic circuitry, e.g., an FPGA (field programmable gate array) or an ASIC (application specific integrated circuit). Processors suitable for the execution of a computer program include, by way of example, both general and special purpose microprocessors, and any one or more processors of any kind of digital computer. Generally, a processor will receive instructions and data from a read only memory or a random access memory or both. The essential elements of a computer are a processor for performing 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, e.g., magnetic, magneto optical disks, 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 memory devices, including by way of example semiconductor memory devices, e.g., EPROM, EEPROM, and flash memory devices; magnetic disks, e.g., internal hard disks or removable disks; magneto optical disks; and CD ROM and DVD-ROM disks. The processor and the memory can be supplemented by, or incorporated in, special purpose logic circuitry.

To provide for interaction with a user, one or more aspects of the disclosure can be implemented on a computer having a display device, e.g., a CRT (cathode ray tube), LCD (liquid crystal display) monitor, or touch screen for displaying information to the user and optionally a keyboard and a pointing device, e.g., a mouse or a trackball, by which the user can provide input to the computer. Other kinds of devices can be used to provide interaction with a user as well; for example, feedback provided to the user can be any form of sensory feedback, e.g., visual feedback, auditory feedback, or tactile feedback; and input from the user can be received in any form, including acoustic, speech, or tactile input. In addition, a computer can interact with a user by sending documents to and receiving documents from a device that is used by the user; for example, by sending web pages to a web browser on a user's client device in response to requests received from the web browser.

With reference to FIG. 1, an illustrative example of a vehicle 100, such as a fuel cell vehicle or fuel cell electric automobile, is provided. The vehicle 100 includes a fuel cell stack 102 that is configured to receive and utilize a gaseous reactant, such as hydrogen, as fuel. Hereinafter, a proton exchange membrane (PEM) electrolyzer is provided and can be configured to split water into oxygen and hydrogen. The hydrogen produced by the PEM electrolyzer may be used as fuel in the vehicle 100 or as fuel in stationary power generation stations, mobile charging stations, or in any other suitable application.

A porous transport layer (PTL) of a membrane electrode assembly (MEA) can be an essential part of the PEM electrolyzers. For instance, the PTL can help remove oxygen gas that results from a reaction within the PEM electrolyzer and the PTL and provides good electrical conductivity for effective electron conduction. As will be addressed by one or more aspects of the present disclosure, different configurations of the PTL are desirable to improve performance and durability of the MEA.

With reference to FIG. 2, an illustrative configuration of a PEM electrolyzer 10 is provided. The PEM electrolyzer 10 includes a first distribution plate 12 and a second distribution plate 14 spaced from the first distribution plate 12. The first and second distribution plates 12, 14 may also be referred to as bipolar plates. The first distribution plate 12 includes an inlet 16 that is configured to receive and carry a fluid into the PEM electrolyzer 10 and an outlet 18 that is configured to receive and carry a fluid away from the PEM electrolyzer 10. The first distribution plate 12 can include an inner surface 20 that includes a flow field pattern 22 that has one or more channels 24. The second distribution plate 14 includes one or more outlets 26 that are configured to receive and carry a fluid away from the PEM electrolyzer 10. The second distribution plate 14 can include an inner surface 28 that includes a flow field pattern 30 that has one or more channels 32. In the present illustrative configuration, the inner surface 28 of the second distribution plate 14 faces the inner surface 20 of first distribution plate 12. According to one aspect, the flow field pattern 30 of the second distribution plate 14 can be different than the flow field pattern 22 of the first distribution plate 12.

The PEM electrolyzer 10 can further include an external circuit 33 that includes a power supply 34 (e.g., DC power source, a battery, etc.) that is communicatively coupled to the first distribution plate 12 and the second distribution plate 14.

With continued reference to FIG. 2, the PEM electrolyzer 10 includes an MEA 35 that has a proton exchange membrane (i.e., membrane) 36 that is arranged between the first distribution plate 12 and the second distribution plate 14. The membrane 36 can have a first side or face 38 that faces the inner surface 20 of the first distribution plate 12 and a second side or face 40 that faces the inner surface 28 of the second distribution plate 14.

The PEM electrolyzer 10 can further include an anode compartment 42 arranged between the first distribution plate 12 and the membrane 36. More particularly, the anode compartment 42 can be arranged between the inner surface 20 of the first distribution plate 12 and the first side 38 of the membrane 36. Additionally, the PEM electrolyzer 10 can include a cathode compartment 44 arranged between the second distribution plate 14 and the membrane 36. More particularly, the cathode compartment 44 can be arranged between the inner surface 28 of the second distribution plate 14 and the second side 40 of the membrane 36.

The MEA 35 can include an anode catalyst layer 46 and a multi-layer porous transport layer (PTL) 48 that are both arranged in the anode compartment 42. In general, the anode catalyst layer 46 can be configured to breakdown and/or separate water molecules. The anode catalyst layer 46 can include a first or inner surface 50 and a second or outer surface 52 that is opposite the inner surface 50. As shown in FIGS. 1 and 2, the inner surface 50 can be coupled to or arranged directly adjacent to the first side 38 of the membrane 36. According to one aspect, the anode catalyst layer 46 can be made of iridium ruthenium oxide, iridium oxide, iridium black, or platinum black, for example.

With reference to FIGS. 1 and 2, the multi-layer PTL 48 can include a first or outer layer 54 and a second or inner layer (i.e., low protrusion layer) 56. The first layer 54 can include a first or inner surface 58 and a second or outer surface 60. The second layer 56 can include a first or inner surface 62 and a second or outer surface 64. As shown in FIG. 2, the first layer 54 can be arranged between the second layer 56 and the first distribution plate 12 and the second layer 56 can be arranged between the anode catalyst layer 46 and the first layer 54. More particularly, with reference to FIG. 2, outer surface 60 of the first layer 54 engages with the inner surface 20 of the first distribution plate 12, the inner surface 58 of the first layer 54 engages with the outer surface 64 of the second layer 56, and the inner surface 62 of the second layer 56 engages with the first side 38 of the membrane 36. According to one aspect, the first layer 54 can have a first thickness between 100 micrometers (μm) and 500 μm and the second layer 56 can have a second thickness between 10 μm and 100 μm.

With reference to FIG. 3, the first layer 54 includes one or more first particles 66 and the second layer 56 includes one or more second particles 68. According to one aspect, the one or more first particles 66 and the one or more second particles 68 can both be made of titanium, but the one or more first particles 66 are larger than the one or more second particles 68. For instance, the one or more first particles 66 can range between 50-100 μm in diameter and the one or more second particles 68 can range between 1-45 μm in diameter. The multi-layer PTL 48 can have an arithmetic mean height (Ra) of 3.0-6 μm and preferably less than 3.8 μm. Additionally or alternatively, the multi-layer PTL can have a maximum height (i.e., distance between highest peak and lowest valley) of 20-22 μm and preferably less than 21.2 μm. Thus, at least a portion of the multi-layer PTL 48 includes low surface roughness which can be desirable to reduce interfacial contact resistance, for example.

Interfacial contact increases between the multi-layer PTL 48 and the anode catalyst layer 46 as a result of using particles that have a smaller diameter. Additionally, using particles that have a smaller diameter can help prevent the anode catalyst layer 46 and/or the membrane 36 from protruding or encroaching in on the multi-layer PTL 48. Preventing and/or avoiding protrusion can be desirable for improving durability of the MEA 35. Additionally or alternatively, with reference to FIG. 4, increasing interfacial contact between the multi-layer PTL 48 and the anode catalyst 46 is desirable to improve electrical performance of the multi-layer PTL 48.

With reference again to FIG. 3, the multi-layer PTL 48 can further include a transition region or protrusion barrier 70 where one or more of the one or more second particles 68 are embedded between and/or interlocked with the one or more first particles 66. The protrusion barrier 70 can be desirable to reduce protrusion of the anode catalyst layer 46 and/or the membrane 36 into the first and/or second layers 54, 56 of the multi-layer PTL 48. The protrusion barrier 70 can include a thickness 71 that is greater than or equal to the second thickness of the of the second layer 56.

With reference again to FIG. 2, the MEA 35 can include a cathode catalyst layer 72 and a gas diffusion layer 74 that are arranged in the cathode compartment 44. The cathode catalyst layer 72 includes a first or inner surface 76 and a second or outer surface 78 spaced from the inner surface 76. According to one aspect, the cathode catalyst layer 72 can comprise platinum black or platinum supported on carbon catalysts, for example. The gas diffusion layer 74 can include a first or inner surface 80 and a second or outer surface 82. In the present illustrative configuration, the outer surface 82 of the gas diffusion layer 74 is arranged adjacent to the inner surface 28 of the second distribution plate 14, the inner surface 80 of the gas diffusion layer 74 is coupled to and/or arranged adjacent to the outer surface 78 of the cathode catalyst layer 72, and the inner surface 76 of the cathode catalyst layer 72 is coupled to and/or arranged adjacent to the second side 40 of the membrane 36.

During operation, water (H₂O) 84 or another fluid is introduced to the PEM electrolyzer 10 via the inlet 16 so that the water 84 can flow across the flow field pattern 22 and through the one or more channels 24. The water 84 moves through the multi-layer PTL 48 and reacts with the anode catalyst layer 46 to form oxygen (O₂) 86 and positively charged hydrogen ions (H+) (i.e., protons) 88. The anode compartment 42 can be configured to carry out a reaction represented by the following equation:

Electrons 90 flow through the external circuit 33 while the hydrogen ions 88 selectively move across the membrane 36 to the cathode compartment 44. At the cathode compartment 44, the hydrogen ions 88 combine with electrons 90 from the external circuit 33 to form hydrogen gas (H₂). The cathode compartment 44 can be configured to carry out a reaction represented by the following equation:

With reference to FIG. 5, a flow diagram of a method 100 of manufacturing a multi-layer porous transport layer is provided.

At 110, the first layer 54 of the multi-layer PTL can be provided and includes the first particles 66.

At 120, a slurry can be applied to the inner surface 62 of the first layer 54. In some configurations, the slurry can be in the form of an ink that includes the second particles 68. According to one aspect, the slurry can contain titanium particles, water, solvents, and/or binders. The titanium particles used in the slurry can be 1-45 μm in diameter can be in the form of powder, flake, or fibrous, for example. The binders can be made of polytetrafluoroethylene (PTFE), perfluoropolyethers (PFPE), polyvinylidene fluoride (PVDF), peroxyacetic acid (PAA), cellulosic hydrocarbons, etc.

At 130, the slurry can be dried on the inner surface 62 of the first layer 54.

At 140, the slurry can be fused to the first layer 54 to form the second layer 56. For instance, sintering can be used so that the slurry is fused or otherwise coupled to the first layer 54. The slurry and the first layer 54 can be sintered at a temperature greater than 600 degrees Celsius (° C.) and less than 1400° C., for example.

A number of implementations have been described. Nevertheless, it will be understood that various modifications may be made without departing from the spirit and scope of the disclosure. Accordingly, other implementations are within the scope of the following claims.

The foregoing description has been provided for purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure. Individual elements or features of a particular configuration are generally not limited to that particular configuration, but, where applicable, are interchangeable and can be used in a selected configuration, even if not specifically shown or described. The same may also be varied in many ways. Such variations are not to be regarded as a departure from the disclosure, and all such modifications are intended to be included within the scope of the disclosure.