HIGH SURFACE AREA ANODE CATALYST FOR AEM ELECTROLYZERS

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of Chinese Patent Application No. 202410702859.0, filed on May 31, 2024. The entire disclosure of the above application is incorporated herein by reference.

FIELD

The present technology relates to advancements in electrochemical systems for efficient hydrogen and oxygen production within Anion Exchange Membrane (AEM) electrolyzers and, more specifically, catalyst layer compositions for use within AEM electrolyzers.

INTRODUCTION

This section provides background information related to the present disclosure which is not necessarily prior art.

The field of electrochemical systems for hydrogen and oxygen production has been a subject of extensive research and development due to the growing demand for clean and sustainable energy sources. Anion Exchange Membrane (AEM) electrolyzers, which facilitate the electrolysis process to generate these gases, are critical components in this domain.

The reliance on precious metals such as platinum (Pt), iridium (Ir), and ruthenium (Ru) as catalysts in AEM electrolyzers has been a significant impediment to cost-effective hydrogen and oxygen production. Despite their catalytic prowess, the exorbitant cost of these materials contributes to the high capital expenditure of electrolyzer systems. This reliance on expensive catalysts renders the production of hydrogen and oxygen via electrolysis economically unviable when compared to conventional energy sources, thus stalling the potential for widespread adoption of this clean technology.

The integration of less-conductive catalysts within electrolytic cells has also presented a considerable challenge. Catalytic nanoparticles, known for their high surface area and potential for high reactivity, are rendered less effective without a mechanism for efficient electron transfer. This inefficiency in electron conduction hampers the overall performance of electrolyzers, creating a critical barrier to their efficacy and broader industrial application.

The use of high concentration alkaline solutions in AEM electrolyzers further compounds the challenges faced in the field. While these solutions facilitate the electrolysis process, they introduce maintenance and operational (M&O) complexities. The corrosive nature of these solutions necessitates robust safety measures, specialized handling, and the use of materials capable of withstanding such caustic environments. The additional requirements for managing these solutions not only increase the operational costs but also impose stringent safety protocols, further complicating the deployment of electrolytic technology.

There is a continuing need for a catalyst layer composition and an associated AEM electrolyzer structure that can efficiently incorporate less-conductive catalysts to provide an alternative to precious metal catalysts, thereby minimizing or eliminating the use of precious metals in the AEM electrolyzer and optimize electron transfer processes in operation. Desirably, the catalyst layer composition and an associated AEM electrolyzer structure reduce the need for caustic alkaline solutions by permitting for operation of the AEM electrolyzer without high concentration alkaline solutions, for enhanced efficiency, safety, and cost-effectiveness of the AEM electrolyzer.

SUMMARY

In concordance with the instant disclosure, a catalyst layer composition and an associated AEM electrolyzer structure that can efficiently incorporate less-conductive catalysts to provide an alternative to precious metal catalysts, thereby minimizing or eliminating the use of precious metals in the AEM electrolyzer, optimize electron transfer processes in operation, and which reduce the need for caustic alkaline solutions by permitting for operation of the AEM electrolyzer without high concentration alkaline solutions, for enhanced efficiency, safety, and cost-effectiveness of the AEM electrolyzer, has surprisingly been discovered.

The present technology includes articles of manufacture, systems, and processes that relate to electrochemical systems and methods for hydrogen and oxygen generation, particularly to the development of catalyst layer compositions and AEM electrolyzers. More specifically, the technology pertains to the design and manufacturing of catalyst layers that provide a high surface area and conductive support in the form of meso porous particles with open pores, combined with less-conductive catalysts that are either grown on the surface of these particles through various deposition methods or mixed and adsorbed by the meso porous particles. The present disclosure further encompasses AEM electrolyzer structures that incorporate these catalyst layers, as well as methods for manufacturing such structures using spraying and decal processes. The technology aims to enhance the efficiency and safety of AEM electrolyzers by improving the surface area and conductive support for the anode catalyst, thereby facilitating the electrochemical reactions within the AEM electrolyzers necessary for the production of hydrogen and oxygen gases.

In one embodiment, a conductive meso porous catalyst layer for an AEM electrolyzer is disclosed, which includes a catalyst composition comprising meso porous particles with open pores, such as Raney nickel with diameters ranging from 5 to 100 micrometers, and a less-conductive catalyst such as nickel iron oxide (e.g., NiFe₂O₄). The less-conductive catalyst is either grown on the surface of the meso porous particles through a growth process or admixed with the meso porous particles. The growth process includes at least one of chemical deposition, electro-chemical deposition, hydrothermal deposition, and an etching of a surface of the meso porous particles, as non-limiting examples. The meso porous particles and the less-conductive catalyst are then either bonded by a thermal process or held together by a binder, providing a cohesive and functional catalyst layer for efficient operation of the AEM electrolyzer, and ensuring efficient electron transfer and enhancing the overall performance of the AEM electrolyzer.

In another embodiment, the present disclosure features an AEM electrolyzer structure that incorporates the aforementioned catalyst layer composition. This structure comprises a cathode side equipped with a bipolar plate or half plate, a porous transport layer, and a catalyst layer. On the anode side, the structure includes a similar bipolar plate or half plate, a porous transport layer, and a meso porous layer formed from the catalyst composition. The meso porous layer is a high surface area and conductive support layer. An anion exchange membrane separates the cathode and anode sides, ensuring efficient ion transfer and electrolysis process within the system.

In a further embodiment, the present disclosure describes a method for manufacturing an AEM electrolyzer structure. This method involves providing the catalyst layer composition as detailed above, applying it to a porous transport layer through a spraying process, and then assembling the AEM electrolyzer structure with the applied catalyst layer composition. The spraying process may utilize a nitrogen airbrush to ensure even distribution and adherence of the catalyst composition to the transport layer.

In yet another embodiment, the present disclosure outlines an alternative method for manufacturing an AEM electrolyzer structure. This method also starts with the provision of the catalyst layer composition. However, in this case, the composition is applied to the porous transport layer using a decal process. This involves casting the catalyst ink having the catalyst layer composition onto a substrate and then transferring the dried ink to the porous transport layer. The AEM electrolyzer structure is then assembled with the applied catalyst layer composition, ensuring a robust and efficient electrolysis system.

In a particular embodiment, a catalyst layer system is affixed to the surface of a porous transport layer (PTL) for an anode side of an electrolyzer. This system is composed of a blend of non-conductive catalytic nanoparticles, such as nickel iron oxide (NiFe₂O₄), and conductive meso-particles made from non-precious materials, such as a nickel alloy, with a high surface area. These components are cohesively bound using a polymeric binder, specifically polytetrafluoroethylene (PTFE), for example, at a concentration of 5-10% by weight, creating a unified layer where the less-conductive catalyst is intimately integrated with the conductive framework provided by the meso-particles.

The layer system is characterized by the dispersion of non-conductive catalytic particles throughout the conductive matrix of metallic meso-particles, such as a nickel alloy. This strategic distribution facilitates a substantial improvement in electron transfer capabilities, thereby enhancing the operational efficiency of the electrolyzer. The result is a system that performs electrolysis more effectively due to the optimized electron pathways within the catalyst layer.

The production of the meso-particles for this catalyst layer system is achieved through methods such as spraying or mechanical transfer processes, followed by thermal post-treatment. This manufacturing approach is notably simpler and more user-friendly compared to traditional methods that require the construction of multiple catalytic and conductive layers or employ complex techniques like electrospinning under high-voltage fields (e.g., electrospinning on 10-30 kV field strength) to produce nanofibers.

By applying precise compression to the PTL during the assembly of the electrolytic cell, the resulting catalyst layer is further rendered more compact and is positioned in closer proximity to the membrane. This arrangement significantly reduces the distance hydroxide ions must travel to reach the membrane, leading to improved electrolyzer performance. Consequently, there is no longer a need for high concentration alkaline solutions or precious metal particles to facilitate electron conduction within the electrolyzer, resulting in a more cost-effective and economically advantageous system.

Further areas of applicability will become apparent from the description provided herein. The description and specific examples in this summary are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure.

DRAWINGS

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

FIG. 1 is a block diagram illustrating a meso porous catalyst layer, according to certain embodiments of the present disclosure.

FIG. 2A is a block diagram illustrating an AEM electrolyzer system, according to certain embodiments of the present disclosure.

FIG. 2B is a schematic illustration of the AEM electrolyzer system depicted in FIG. 2B, according to certain embodiments of the present disclosure.

FIG. 3 is a flowchart illustrating a method for manufacturing an AEM electrolyzer system, according to certain embodiments of the present disclosure.

FIG. 4 is a flowchart illustrating a method for manufacturing an AEM electrolyzer structure, according to certain embodiments of the present disclosure.

FIG. 5 is a flowchart illustrating a method for manufacturing an AEM electrolyzer system, according to certain embodiments of the present disclosure.

FIG. 6A is a flowchart illustrating a method for manufacturing an anode porous transport layer, according to certain embodiments of the present disclosure.

FIG. 6B is a flowchart extending from FIG. 6A and further illustrating the method for manufacturing an anode porous transport layer, according to certain embodiments of the present disclosure.

FIG. 7A is a flowchart illustrating a method for manufacturing an anode porous transport layer, according to certain embodiments of the present disclosure.

FIG. 7B is a flowchart extending from FIG. 7A and further illustrating the method for manufacturing an anode porous transport layer, according to certain embodiments of the present disclosure.

FIG. 7C is a flowchart extending from FIG. 7B and further illustrating the method for manufacturing a porous transport layer from FIG. 7A, according to certain embodiments of the present disclosure.

FIG. 8 is a BOC polarization curve associated with an electrochemical cell manufactured according to certain embodiments of the present disclosure.

DETAILED DESCRIPTION

The following description of technology is merely exemplary in nature of the subject matter, manufacture and use of one or more inventions, and is not intended to limit the scope, application, or uses of any specific invention claimed in this application or in such other applications as may be filed claiming priority to this application, or patents issuing therefrom. Regarding methods disclosed, the order of the steps presented is exemplary in nature, and thus, the order of the steps can be different in various embodiments, including where certain steps can be simultaneously performed, unless expressly stated otherwise. “A” and “an” as used herein indicate “at least one” of the item is present; a plurality of such items may be present, when possible. Except where otherwise expressly indicated, all numerical quantities in this description are to be understood as modified by the word “about” and all geometric and spatial descriptors are to be understood as modified by the word “substantially” in describing the broadest scope of the technology. “About” when applied to numerical values indicates that the calculation or the measurement allows some slight imprecision in the value (with some approach to exactness in the value; approximately or reasonably close to the value; nearly). If, for some reason, the imprecision provided by “about” and/or “substantially” is not otherwise understood in the art with this ordinary meaning, then “about” and/or “substantially” as used herein indicates at least variations that may arise from ordinary methods of measuring or using such parameters.

All documents, including patents, patent applications, and scientific literature cited in this detailed description are incorporated herein by reference, unless otherwise expressly indicated. Where any conflict or ambiguity may exist between a document incorporated by reference and this detailed description, the present detailed description controls.

Although the open-ended term “comprising,” as a synonym of non-restrictive terms such as including, containing, or having, is used herein to describe and claim embodiments of the present technology, embodiments may alternatively be described using more limiting terms such as “consisting of” or “consisting essentially of.” Thus, for any given embodiment reciting materials, components, or process steps, the present technology also specifically includes embodiments consisting of, or consisting essentially of, such materials, components, or process steps excluding additional materials, components or processes (for consisting of) and excluding additional materials, components or processes affecting the significant properties of the embodiment (for consisting essentially of), even though such additional materials, components or processes are not explicitly recited in this application. For example, recitation of a composition or process reciting elements A, B and C specifically envisions embodiments consisting of, and consisting essentially of, A, B and C, excluding an element D that may be recited in the art, even though element D is not explicitly described as being excluded herein.

As referred to herein, all compositional percentages are by weight of the total composition, unless otherwise specified. Disclosures of ranges are, unless specified otherwise, inclusive of endpoints and include all distinct values and further divided ranges within the entire range. Thus, for example, a range of “from A to B” or “from about A to about B” is inclusive of A and of B. Disclosure of values and ranges of values for specific parameters (such as amounts, weight percentages, etc.) are not exclusive of other values and ranges of values useful herein. It is envisioned that two or more specific exemplified values for a given parameter may define endpoints for a range of values that may be claimed for the parameter. For example, if Parameter X is exemplified herein to have value A and also exemplified to have value Z, it is envisioned that Parameter X may have a range of values from about A to about Z. Similarly, it is envisioned that disclosure of two or more ranges of values for a parameter (whether such ranges are nested, overlapping or distinct) subsume all possible combination of ranges for the value that might be claimed using endpoints of the disclosed ranges. For example, if Parameter X is exemplified herein to have values in the range of 1-10, or 2-9, or 3-8, it is also envisioned that Parameter X may have other ranges of values including 1-9, 1-8, 1-3, 1-2, 2-10, 2-8, 2-3, 3-10, 3-9, and so on.

When an element or layer is referred to as being “on,” “engaged to,” “connected to,” or “coupled to” another element or layer, it may be directly on, engaged, connected 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” 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.

Although 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 when used herein 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 embodiments.

Spatially relative terms, such as “inner,” “outer,” “beneath,” “below,” “lower,” “above,” “upper,” and the like, may be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures. Spatially relative terms may be intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as “below”, or “beneath” other elements or features would then be oriented “above” the other elements or features. Thus, the example term “below” can encompass both an orientation of above and below. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.

The present technology improves the efficiency and safety of electrolytic cells by introducing a meso porous layer composed of meso porous particles with open pores, which significantly enhances catalytic activity. This innovative approach allows for the use of lower KOH solution concentrations, contributing to a safer maintenance and operational environment, and eliminates the need for precious metals, thus reducing costs. The manufacturing process is simplified, resulting in a more user-friendly and cost-effective production, while also achieving lower catalyst loading without compromising the high performance, stability, and durability of the electrolyzer.

FIG. 1 illustrates a meso porous catalyst layer 100 formed from a catalyst composition 110, which is a critical component of the AEM electrolyzer. The catalyst composition 110 within this layer includes meso porous particles 112, characterized by open pores 114 that facilitate catalytic reactions. The meso porous particles 112 may be Raney nickel as a non-limiting example. One of ordinary skill in the art may also select other suitable materials for the meso porous particles 112 within the scope of the present disclosure.

The open pores 114 of the present disclosure may be provided by certain activation processes, for example. Activation process within the scope of this disclosure will include, in order, first, providing the alloy without pores, and then providing the less-conductive catalyst, and then forming the pores in the alloy by leaching out the aluminum, and then, finally, application of the less-conductive catalyst. It should be appreciated that the application of the less-conductive catalyst may be completed substantially simultaneously with the formation of the pores, for example, by a leaching process, as described further herein. The employment of pre-activated particles, or the employment of other suitable activation process, are also contemplated and considered to be within the scope of the present disclosure.

In particular, where the meso porous particles 112 include the Raney nickel, the Raney nickel may be manufactured through the activation process, which involves the selective leaching of aluminum from NiAl alloy particles using strong alkaline chemicals such as KOH. This activation process creates a high surface area material that is highly reactive. As used herein, the term “high surface area” means a surface area of a particle that is a typical high range would be around 100 m²/g or more. One of ordinary skill in the art may also select other suitably high surface area parameters for the meso porous particles, as desired.

Due to its reactivity, activated Raney nickel must be carefully stored under specific conditions to maintain its structural integrity. If exposed to air while dry, the material can spontaneously ignite, resulting in the loss of its high surface area. Consequently, activated Raney nickel is typically preserved in water or diluted KOH solution to prevent such occurrences. Handling activated Raney nickel presents challenges, particularly during processes such as spraying, drying of catalyst layers, and any form of heat treatment. Therefore, to mitigate the risk of combustion, these procedures are conducted under an inert atmosphere such as Argon, as a non-limiting example.

An alternative approach to circumvent this issue involves forming the catalyst layer using NiAl alloy and subsequently initiating the activation process. This method allows for the creation of the mesoporous structure after the catalyst layer has been established. At least some of the ‘less conductive’ catalyst will adhere to the newly formed mesoporous surface during activation, and at least a portion may be washed away. To address this challenge, one potential solution is to synthesize the less-conductive catalyst directly within or on the surface of the preformed catalyst layer.

The less-conductive catalyst 116, is strategically integrated with the meso porous particles 112, either through a deposition process or by being admixed and adsorbed. This integration is necessary for the performance of the catalyst, as it ensures a high degree of contact between the catalyst and reactants. When the less-conductive catalyst 116 is introduced to activated Raney nickel, the risk of ignition is reduced, yet the potential for combustion remains a concern, and the use of an inert gas environment such as Argon, for example, is advised during handling. The less-conductive catalyst 116 may be at least one of nickel iron oxide (NiFe₂O_x), Fe-LDH (i.e., layered double hydroxide), high entropy multi-metal LDH like FeNiCoMnCr-LDH, and NiFeCoO_x, as particular non-liming examples. A skilled artisan may also select other suitable materials for the less-conductive catalyst 116 consistent with the present disclosure, as desired.

It should be appreciated that conductivity is the inverse of resistance. Conductivity quantifies how well a material conducts electricity. Higher conductivity values mean better electrical flow. In view of this understanding, as used herein, the term “less-conductive”pertains to a catalyst, designated as 116, which exhibits at least the following characteristics.

In the event that the catalyst 116 is provided in a powdered state, the catalyst 116 is required to be compacted between a pair of gold-coated copper plates for testing to determine that the catalyst 116 is sufficiently “less-conductive,” resulting in a compressed layer with a thickness of 0.1 millimeters. The compression must be executed at a pressure of 1 Megapascal (MPa). The resistance specific to the area, ascertained between the gold-coated copper plates, must exceed 100 milliohm-square centimeters (mOhm cm²). This measurement of resistance must be conducted while maintaining the pressure at 1 MPa.

In the event that the catalyst 116 is synthesized atop mesoporous particles, the catalyst 116 must be detached to yield a powdered form for such testing. In situations where detachment is not feasible, the catalyst 116 should be cultivated on an alternative substrate that permits its subsequent removal for testing to determine that the catalyst 116 is sufficiently “less-conductive.”

One skilled in the art may also select other suitable testing parameters for determining whether or not the catalyst 116 is sufficiently “less-conductive” within the meaning of the present disclosure, as desired.

The meso porous particles 112 and the less-conductive catalyst 116 are one of bonded by a thermal process, and held together by the binder 118. It should be appreciated that the meso porous particles 112 are what are bonded or held by the binder 118, and not necessarily the less-conductive catalyst 116, when the binder 118 is employed. As a non-limiting example, the thermal process can be a plasma spraying process. One of ordinary skill in the art may also select other suitable thermal processes for the bonding of the meso porous particles 112 and the less-conductive catalyst 116 within the scope of the present disclosure.

Where the binder 118 is used, the binder 118 can be a polytetrafluoroethylene (PTFE) dispersion as one non-limiting example, serves to maintain the structural integrity of the catalyst composition by holding the meso porous particles 112 and the less-conductive catalyst 116 together. It should be appreciated that one skilled in the field may also select other suitable materials for the binder 118 under the teachings of the present disclosure.

The open pores 114 of the meso porous particles 112 may be selected with sizes ranging from 2 nanometers to 5 micrometers, more particularly from 5 nanometers to 1 micrometer, and most particularly between 20 nm and 500 nm in diameter. In a most particular embodiment, the open pores may have a size ranging from 10 nanometers to 5 micrometers. The open pores 114 may provide an optimized structure for enhanced catalytic reactions within the AEM electrolyzer. A skilled artisan may select other suitable ranges of size for the open pores 114 under the present disclosure, as desired.

The meso porous particles 112, which may be the Raney nickel as a non-limiting example, are a significant portion of the catalyst composition 110, and may make up 60-95% by weight, for example. The precise size range of the open pores, between 10 nm and 50 nm in diameter, may be selected to maximize the surface area available for catalysis while maintaining structural stability. The less-conductive catalyst 116, which may be nickel iron oxide (NiFe₂O₄) as a non-limiting example, is carefully chosen for its catalytic properties. The less-conductive catalyst 116 may constitute 1-20% by weight of the catalyst composition 110. The binder 118, which may be a PTFE dispersion, may be present at a concentration of 3-15% by weight within the catalyst composition 110, ensuring that the catalyst particles are adequately bonded to the support structure. Other suitable concentrations for the meso porous particles 112, the less-conductive catalyst 116, and the binder 118 may also be employed, as desired.

The meso porous layer is affixed to an additional conductive support layer, known as a porous transport layer (PTL), which is shown as 234 in FIG. 2B. The PTL may feature additional open pores up to 1 millimeter in size, for example. The PTL is essential for facilitating effective mass transport and electron flow within the electrolyzer, contributing to the overall efficiency of the system.

The catalyst particles may be strategically grown or deposited as well onto the surface areas of the conductive support (e.g., the meso porous layer) to enhance electrochemical reactions, particularly within the open pores, to maximize the active surface area available for electrolytic reactions. This design consideration may be employed for enhancing the electron transfer efficiency, which directly impacts the performance and stability of the AEM electrolyzer.

Typically, the microporous layer is added on top of the additional conductive support. However, where the additional conductive support is metal foam with the additional open pores, the microporous layer may alternatively engineered to ensure that the catalyst particles are either distributed on an outer surface of the metal foam or uniformly distributed within the additional open pores of the metal foam. This uniform distribution may be desired for optimizing the utilization of the catalyst and promoting uniform reaction rates across the electrolyzer. Additionally, in certain examples, the conductive support may undergo a surface modification process to increase the affinity of the catalyst particles to the support, ensuring a strong bond and high durability of the meso porous catalyst layer 100.

The conductive support with open pores may be seamlessly integrated into the AEM electrolyzer, forming an interface with adjacent layers that minimizes potential barriers to ion and electron transport. This integration is optimized for operation in specific ranges of pH, temperature, and electrolyte concentration, making the system suitable for a wide variety of electrolysis applications. The design also allows for compatibility with various types of less-conductive catalysts, providing flexibility in catalyst selection based on desired electrolysis performance characteristics.

Referring now to FIGS. 2A and 2B an AEM electrolyzer system 200 is depicted, which includes an anion exchange membrane 210, a cathode side 220, and an anode side 230. The cathode side 220 comprises a bipolar plate 222, a porous transport layer 224, and a catalyst layer 226. The anode side 230 includes a bipolar plate 232, a porous transport layer 234, and a meso porous catalyst layer 236 derived from the catalyst composition. The meso porous catalyst layer 236 on the anode side is specifically configured to enhance electron transfer, which may provide for efficient hydrogen generation.

With reference to FIG. 3 a flowchart describing a method for manufacturing an AEM electrolyzer system is presented, and which encompasses steps 310 to 330, and particularly involving a spraying procedure. The method may include a step 310 of providing the catalyst composition as described herein. A step 320 may include applying a meso porous catalyst layer to a porous transport layer by a spraying process that incorporates the catalyst composition. The method may also include a step 330 that involves assembling the AEM electrolyzer structure with the meso porous catalyst layer applied to the porous transport layer. The spraying process may utilize a nitrogen airbrush, which may be selected for its ability to provide a uniform and fine distribution of the catalyst composition onto the porous transport layer.

FIG. 4 outlines a method for manufacturing an AEM electrolyzer structure, and which includes steps 410 to 430. A step 410 involves providing the catalyst composition as described herein. A step 420 includes applying a meso porous catalyst layer to a porous transport layer by a decal process. A step 430 as shown in FIG. 4 involves assembling the AEM electrolyzer structure with the meso porous catalyst layer applied to the porous transport layer. The decal process may involve casting a catalyst ink that includes the catalyst composition onto a substrate and transferring the catalyst ink after drying to the porous transport layer. This decal process may be chosen for its precision and ability to create a uniform catalyst layer with controlled thickness.

FIG. 5 illustrates a method for manufacturing an AEM electrolyzer system, and which includes steps 510 to 530, and particularly involving a decal procedure. A step 510 involves preparing the catalyst composition as described herein. A step 520 as shown in FIG. 5 includes applying the meso porous catalyst layer to a porous transport layer for placement on an anode side of an anion exchange membrane. A step 530 involves assembling the AEM electrolyzer system with a cathode side and anode side separated by the anion exchange membrane.

The method may also include a step of activating the meso porous particles to enhance catalytic activity. The assembling step may include aligning bipolar plates or half plates with the anion exchange membrane to form an integrated cell structure. The method may also include a step of conditioning the anion exchange membrane in alkali-ion form prior to assembly. The applying step may further include a thermal treatment to sinter the catalyst layer composition onto the porous transport layers, in certain examples.

The method may further include a step of testing the AEM electrolyzer system for gas purity and efficiency. It may also include a step of incorporating safety features into the system to prevent gas mixing. The assembling step may include sealing the anion exchange membrane between the cathode side and anode side to prevent leakage.

The method may also include a step of optimizing the flow of aqueous alkaline electrolyte through the AEM electrolyzer system. The applying step may include a precision coating technique to achieve a desired catalyst layer thickness. The method may further include a step of integrating the AEM electrolyzer system with a power source for electrolysis operation. The assembling step may include configuring the AEM electrolyzer system for modular scalability.

The method may also include a step of calibrating the AEM electrolyzer system for specific electrolysis applications. The method may include a step of implementing a monitoring system to track the performance of the AEM electrolyzer system. The assembling step may include the use of automated assembly techniques for mass production. The method may also include a step of conducting environmental impact assessments for the AEM electrolyzer system. The applying step may include a layer-by-layer deposition technique for the catalyst layer composition. The method may further include a step of incorporating renewable energy sources into the operation of the AEM electrolyzer system. The assembling step may include a final inspection process to ensure compliance with industry standards. Other suitable steps for the methods as described and shown in FIGS. 3 and 4 are contemplated and also considered to be within the scope of the present disclosure.

FIGS. 6A to 6B are flowcharts that describe a method for manufacturing an anode porous transport layer according to a more specific embodiment of the disclosure, and particularly providing a spraying procedure. A step 602 involves tailoring a nickel foam to a predetermined size according to the specifications of the electrolytic cell. A step 604 as shown in FIGS. 6A and 6B includes sequentially washing the tailored nickel foam in a cold HCL solution, pure water, and an ethanol and water mixture. A step 606 involves drying the washed nickel foam at ambient temperature. A step 608 includes preparing a fresh coating solution by mixing Fe(NO₃)₃·9 H₂O with water.

A step 610 of the method also involves immersing the dried nickel foam fully into the coating solution, removing it to drain excess liquid, and drying with paper. A step 612 further includes heating the coated nickel foam in an oven and repeating the immersion, draining, and heating process for a total of three cycles. A step 614 of the method shown in FIGS. 6A to 6B also involves compressing the heated nickel foam to a reduced thickness. Advantageously, and as described further herein, the reduced thickness may be less than about 0.3 mm. Other suitable dimensions for the reduced thickness may also be used within the scope of the present disclosure.

A step 616 includes preparing a catalyst ink by ultrasonically mixing wet Raney Nickel with solids, NiFe₂O₄ as a less-conductive catalyst, and water, then adding a PTFE dispersion and shaking the mixture by hand without further ultrasonic mixing. A step 618 as shown in FIGS. 6A to 6B involves spraying the prepared catalyst ink onto the compressed nickel foam using a nitrogen airbrush on a heated plate within a nitrogen environment.

A step 620 includes sintering the nickel foam sprayed with the prepared catalyst ink at a temperature range, and in an argon atmosphere to consolidate the catalyst layer and to form a robust conductive network. This sintering process may be desired for achieving sufficiently high performance and durability required for efficient electrolyzer operation. A step 622 as shown in FIGS. 6A to 6B involves cooling the sintered nickel foam under an argon atmosphere and vacuum conditions. A step 624 includes rapidly immersing the cooled nickel foam in a water-ethanol mixture immediately after opening the oven to provide a prepared PTL with a meso porous catalyst layer. A step 626 involves storing the prepared PTL in a water-ethanol mixture within a containment bag. A step 628 as shown in FIGS. 6A to 6B includes assembling the prepared PTL into an electrolytic cell comprising a wet anion exchange membrane and a KOH solution to complete the manufacturing process of the anode PTL for the electrolytic cell. A BOL polarization curve associated with such an electrolytic cell is depicted in FIG. 8.

Returning to FIGS. 6A to 6B, the method includes steps 602 to 628 and may have the specific parameters for each step detailed as follows. The nickel foam may be tailored to a thickness of 1 mm and washed in a 5 mol HCL solution for 15 minutes, for example. The coating solution may be prepared with 3 g of Fe(NO₃)₃·9 H₂O mixed with 200 g of water, for example. The heating of the coated nickel foam may be performed at 280° C. for 15 minutes, for example. The compressed nickel foam may be reduced to a thickness of approximately 0.3 mm, for example. The catalyst ink may comprise 5 g of wet Raney Nickel with 50% solids, 0.2 g of NiFe₂O₄, and 3.2 g of water, with an addition of 2 g of a 6% PTFE dispersion, for example. The spraying step may be conducted on a heated plate at 115° C. within a nitrogen environment, for example. This step may be desired for forming a strong bond between the catalyst particles and the nickel foam, which may facilitate structural integrity and performance of the catalyst layer. The sintering step may be carried out at a temperature range of 340-360° C., for example. The electrolytic cell may comprise a 90 μm wet anion exchange membrane and a 0.1 mol KOH solution, for example. These parameters may be selected to optimize the electron transfer efficiency of the catalyst layer and overall performance of the AEM electrolyzer, and one of ordinary skill in the art may select suitable parameters consistent with these teachings within the scope of the present disclosure.

In particular embodiments, the nickel foam may be tailored to a thickness of 0.3 mm. The HCL solution may have a concentration of 5 mol. The coating solution may comprise 3 g of Fe(NO₃)₃·9 H₂O mixed with 200 g of water. The heating of the coated nickel foam may be performed at 280° C. for 15 minutes. The compressed nickel foam may have a thickness of approximately 0.3 mm.

The catalyst ink may comprise 5 g of wet Raney Nickel with 50% solids, 0.2 g of NiFe₂O₄, and 3.2 g of water, with an addition of 2 g of a 6% PTFE dispersion. The spraying step may be performed on a heated plate at 115° C. within a nitrogen environment. The sintering step may be performed at a temperature range of 340-360° C. The sintering step may be performed in an inert gas atmosphere, such as Argon as one non-limiting example. The electrolytic cell may comprise a 90 μm wet anion exchange membrane and a 0.1 mol KOH solution.

FIGS. 7A to 7C are flowcharts that describe a method for manufacturing an anode porous transport layer, and particularly involving a decal procedure. A step 702 involves tailoring a nickel foam to a size specified for the electrolytic cell. A step 704 includes washing the nickel foam in a cold HCL solution for a set duration, followed by rinsing in pure water and an ethanol and water mixture. A step 706 as shown in FIGS. 7A to 7C involves drying the nickel foam at ambient temperature. A step 708 includes preparing a fresh coating solution by mixing Fe(NO₃)₃·9 H₂O with water.

A step 710 involves immersing the nickel foam fully into the coating solution, removing it to drain excess liquid, and drying with paper. A step 712 as shown in FIGS. 7A to 7C includes heating the coated nickel foam in an oven and repeating this process a number of times. A step 714 involves compressing the nickel foam to a reduced thickness. A step 716 includes preparing a catalyst ink by ultrasonically mixing a mixture of nickel and aluminum powder, NiFe₂O₄, and an isopropanol and water dispersion.

A step 718 involves cooling the ink during ultrasonic mixing and replenishing any evaporated isopropanol to maintain the correct ink weight. A step 720 as shown in FIGS. 7A to 7C includes adding a PTFE dispersion to the ink and shaking by hand without further ultrasonic mixing. A step 722 involves casting the ink onto a mirror-grade stainless steel sheet to a set thickness using a knife coating machine.

A step 724 includes drying the stainless steel coated with the ink in an oven. A step 726 involves pressing the nickel foam onto the stainless steel upon the drying of the ink to transfer the ink layer to the foam. A step 728 as shown in FIGS. 7A to 7C includes sintering the PTL in an oven for a set duration in an air atmosphere. A step 730 involves activating the sintered PTL in a solution of KOH and ethanol at room temperature for a set duration. A step 732 includes increasing KOH concentration and continuing the activation at an elevated temperature for an additional duration until no bubbles are observed to provide an activated PTL with a meso porous catalyst layer. A step 734 as shown in FIGS. 7A to 7C involves assembling the activated PTL into an electrolytic cell to complete the anode PTL manufacturing process. The method includes steps 702 to 734.

The nickel foam may be tailored to a thickness of 1 mm. The HCL solution may have a concentration of 5 mol. The coating solution may comprise 3 g of Fe(NO₃)₃ mixed with 200 g of water. The compressed nickel foam may have a thickness of approximately 0.26 mm. The catalyst ink may comprise 16 g of a 50:50 mixture of nickel and aluminum powder, 0.5 g of NiFe₂O₄, and 7 g of an isopropanol and water dispersion, with an addition of 3.05 g of a 60% PTFE dispersion.

The ink may be cast onto the stainless steel sheet to a thickness of 0.3 mm. The drying of the stainless steel coated with the ink may be performed in an 80° C. oven. The sintering of the PTL may be performed at 360° C. for 15 minutes. The activation of the sintered PTL may be performed in a solution of 1 mol KOH and 20 g of ethanol at room temperature for 1.5 hours, followed by an increase in KOH concentration to 5 mol and continued activation at 80° C. for an additional 1.5 hours.

In further embodiments, for example, in order to ensure the optimal performance of the catalyst layer, it should be appreciated that a post-treatment compression step may further employed. After the sintering process, the nickel foam with the catalyst layer may be subjected to a calibrated compression force, which densifies the layer and reduces the distance between the catalyst and the anion exchange membrane. This compression may be carefully controlled to maintain the integrity of the meso porous structure while enhancing the contact efficiency, which may be critical for the rapid transport of hydroxide ions during the electrolysis process.

It should also be appreciated that the final assembly of the AEM electrolyzer may involve the precise alignment of the anode and cathode sides with the anion exchange membrane sandwiched in between. Special attention may be given to the sealing process to militate against leakage and ensure the integrity of the electrolytic cell. The assembled cell may then be then subjected to a conditioning process, where it is operated under predetermined conditions to stabilize the membrane and the catalyst layers, thereby ensuring consistent and reliable performance upon deployment.

In addition to the aforementioned manufacturing steps, the present technology contemplates various modifications to the catalyst layer composition to cater to different electrolysis applications. For instance, the less-conductive catalyst may be substituted with alternative materials that offer specific advantages in terms of reactivity or cost. Similarly, the polymeric binder can be selected from a range of materials to adjust the mechanical properties of the catalyst layer, such as flexibility or adhesion strength.

The present disclosure may also encompass a method for scaling the production of the AEM electrolyzer structures. This method may involve the use of automated or semi-automated equipment for the spraying and decal processes, which allows for high-throughput manufacturing while maintaining the precision and quality of the catalyst layers. The scalability of the manufacturing process may be desired for meeting the demands of large-scale hydrogen production facilities.

Furthermore, the present disclosure may provide for a comprehensive testing protocol to evaluate the performance of the AEM electrolyzer under various operational conditions. This protocol may include testing for gas purity, electrolysis efficiency, and long-term stability. The results from these tests may be used to refine the catalyst layer composition and the manufacturing parameters, ensuring that the AEM electrolyzer meets the stringent requirements of industrial hydrogen production.

Advantageously, the system and methods of the present disclosure offers a multitude of benefits over existing solutions, including high catalytic activity and the use of lower concentrations of KOH solution, which contribute to a safer maintenance and operational environment. It eliminates the need for precious metals, thereby reducing dependency on costly materials. The manufacturing processes are not only easier but also more user-friendly, leading to lower manufacturing costs. Additionally, the system and methods of the present disclosure require lower catalyst loading while still delivering high performance, stability, and durability, making it an economically and technically superior alternative to current electrolysis systems.

EXAMPLES

Example embodiments of the present technology are provided with reference to the several figures enclosed herewith.

Example 1: Pre-Treatment Ni Foam and Spraying Process to Make Anode

Example 1 describes the process of pre-treating nickel foam with a spraying process to create an anode porous transport layer (PTL) for use in an electrolytic cell.

In the initial step, a 1 mm thick nickel foam is cut to the dimensions required by the electrolytic cell design. This foam is then subjected to a series of washes-first in a cold 5 mol HCL solution for 15 minutes, followed by rinsing in pure water, and then in a 50:50 mixture of ethanol and water. After the washing steps, the nickel foam is left to dry at ambient temperature. A fresh coating solution is prepared by mixing 3 g of Fe(NO₃)₃·9 H₂O with 200 g of water. The nickel foam is fully immersed in this solution, removed to allow excess liquid to drain off, and then placed in an oven at 280° C. for 15 minutes. This immersion and heating process is repeated three times to ensure thorough coating. Finally, the nickel foam is compressed to approximately 0.3 mm thickness.

The second step involves preparing the catalyst ink for spraying. This is done by ultrasonically mixing 5 g of wet Raney Nickel (with 50% solids), 0.2 g of NiFe₂O₄ (a less-conductive catalyst), and 3.2 g of water. To this mixture, 2 g of a 6% PTFE dispersion is added, and the mixture is then shaken by hand without further ultrasonic mixing.

For the spraying process, the catalyst ink is applied to the nickel foam using a nitrogen airbrush. This is performed on a heated plate at 115° C. within a nitrogen environment, such as a glovebox or with nitrogen flushing over the plate. The nickel foam is then sintered at temperatures ranging from 340-360° C., and subsequently in an argon atmosphere. The system is kept under argon, vacuumed with a pump, and allowed to cool. Once cooled, the nickel foam is quickly dipped into a water-ethanol mixture after the oven is opened and then stored in a bag containing the same mixture.

In the final assembly step, the treated PTL is integrated into an electrolytic cell, which includes a 90 μm wet anion exchange membrane and a 0.1 mol KOH solution. The beginning of life (BOL) polarization curve, which is not depicted here, would typically be provided to illustrate the electrochemical performance of the assembled cell.

Example 2: Preparation of a Meso Porous Particle Layer

This example outlines a detailed procedure for preparing a mesoporous particle layer, which involves several steps including mixing, casting, drying, sintering, activating, washing, and growing a multi-metal high entropy Layered Double Hydroxide (LDH) within the mesopores. The process is designed for use in the construction of an Anion Exchange Membrane (AEM) cell, which is a component commonly used in electrochemical devices such as fuel cells and electrolyzers.

A mixture is created by combining 16 g of a 50:50 NiAl alloy powder with 7 g of a 50:50 isopropanol/water solution and 0.2 g of oxalic acid, using mechanical stirring. Both the individual components and the resulting mixture are cooled to approximately 10° C.

To this cooled mixture, 3.05 g of a 60% PTFE dispersion is added and briefly stirred using a glass rod.

The resultant ink is then applied to a sheet of nickel foam, which has been pre-compressed to a thickness of 0.3 mm, to form a conductive layer. Knife casting may be the preferred method for this application.

The layer is dried at 80° C. and then sintered at 360° C. for 10 minutes in an air atmosphere.

To generate mesopores within the layer, it is activated by immersion in a 1 molar aqueous KOH solution with a 20% ethanol content at room temperature for 1.5 hours. The ethanol assists in the KOH solution's penetration into the catalyst layer and promotes the dissolution of aluminum. Following the initial activation, the KOH concentration is increased to 5 molar, and the layer is further activated at 80° C. for an additional 1.5 hours or until bubble formation ceases, indicating the end of the activation process.

Subsequently, the layer is washed multiple times with a 20% ethanol-water solution until the pH of the wash fluid is below 9. A 5 cm×5 cm section is cut from the layer and kept in a moist condition.

To cultivate a multi-metal high entropy LDH within the mesopores of this section, the following solution is prepared:

A total of 15 mmol of the following chemicals are dissolved in 500 ml of water:

Additionally, 0.36 mol of urea and 0.15 mol of NH4F are added and dissolved in the solution.

This solution is then transferred into a PTFE-coated autoclave, and the previously cut 5 cm×5 cm sample is placed inside. The autoclave is heated to 120° C. for 12 hours.

Once the autoclave has cooled, the sample is washed with a 20% ethanol-water solution and stored in a wet state until it is assembled into an AEM cell.

Example 3: Pre-Treatment Ni Foam and Decal Process to Make Anode

Example 3 outlines the procedure for pre-treating nickel foam using a decal process to fabricate an anode porous transport layer (PTL) for an electrolytic cell. The following example illustrates a method for the decal application of a catalyst layer. Generally, the decal processes within the scope of this disclosure will include, in order, first, providing the alloy without pores, and then providing the less-conductive catalyst, and then forming the pores in the alloy by leaching out the aluminum, and then, finally, application of the less-conductive catalyst. It should be appreciated that the application of the less-conductive catalyst may be completed substantially simultaneously with the formation of the pores by the leaching process.

The process begins with cutting a 1 mm thick nickel foam to the dimensions required by the electrolytic cell. This foam is then thoroughly washed, first in a cold 5 mol HCL solution for 15 minutes, followed by rinsing in pure water, and subsequently in a 50:50 ethanol and water mixture. After the washing steps, the nickel foam is air-dried at room temperature.

A fresh coating solution is prepared by dissolving 3 g of Fe(NO₃)₃·9 H₂O in 200 g of water. The nickel foam is fully immersed in this solution, removed to allow excess liquid to drain off, and then dried using paper. This coated foam is then placed in an oven preheated to 280° C. for 15 minutes. This immersion and drying cycle are repeated three times to ensure a consistent coating.

For the decal ink preparation, 16 g of a 50:50 alloy of nickel and aluminum powder is ultrasonically mixed with 0.5 g of NiFe₂O₄, a less-conductive catalyst, and 7 g of an isopropanol and water dispersion. During the mixing process, the ink is cooled to below 10° C. to prevent overheating, and any evaporated isopropanol is replenished to maintain the correct weight. The ink is kept below 10° C., and then 3.05 g of a 60% PTFE dispersion is added. The mixture is then shaken by hand without further ultrasonic mixing.

In the decal step, the ink is cast onto a mirror-grade stainless steel sheet to a thickness of 0.3 mm using a knife coating machine. The stainless steel provides an ideal surface for the ink to release cleanly onto the nickel foam. The coated stainless steel is then placed in an 80° C. oven until the ink layer is dry. The nickel foam is then pressed onto the ink-coated stainless steel to a thickness of 0.26 mm, effectively transferring the ink layer to the foam.

The PTL is then sintered in an oven at 360° C. for 15 minutes in an air atmosphere and allowed to cool. The PTL is subsequently activated by immersing it in a solution of 1 mol KOH and 20 g of ethanol at room temperature for 1.5 hours. The ethanol aids in the penetration of the liquid into the catalyst layer and facilitates the dissolution of aluminum. After the initial activation period, the KOH concentration is increased to 5 mol, and the PTL is further activated at 80° C. for an additional 1.5 hours or until no bubbles are observed, indicating the completion of the activation process.

Example 4: Activation Process for Catalyst Layer Formation

The following example illustrates a method for the activation formation of a catalyst layer. Generally, like the decal process, activation processes within the scope of this disclosure will include, in order, first, providing the alloy without pores, and then providing the less-conductive catalyst, and then forming the pores in the alloy by leaching out the aluminum, and then, finally, application of the less-conductive catalyst. It should be appreciated that the application of the less-conductive catalyst may be completed substantially simultaneously with the formation of the pores by the leaching process.

In this example, an alloy is initially prepared. For example, the alloy may consist of Ni, Fe, Co, and Al is prepared with a mass ratio of Ni:Fe:Co:Al=31:8:1:60. The particle size of the alloy is maintained within the range of 10-25 μm, and a total of 15 g of the alloy is used for the process.

A dispersion is then prepared by combining 3 g of 60% PTFE in water with 7 g of isopropanol/water in a 1:1 ratio and 0.2 g of oxalic acid. This mixture is kept cool at approximately 5° C.

The alloy is then added to the dispersion under cool conditions. Low-speed stirring is applied for a brief duration to ensure a homogeneous mixture. Viscosity-enhancing agents may be added to the slurry if necessary, along with substances that promote the formation of hydrophilic pores.

The slurry is then applied to the surface of a compressed Ni foam with a thickness of 0.3 mm using a knife coating technique. The target dry mass loading of the applied slurry is set at approximately 30 mg/cm².

The coated layer is dried, and the PTFE is sintered at a temperature of 360° C. in an air atmosphere. The alloy within the layer is then activated as described herein above.

If necessary, in certain activation processing, the slightly wet layer is pressed again to achieve a uniform thickness of about 0.3 mm. The activated layer may be stored in water or diluted KOH solution to preserve its structure and reactivity. The layer is kept in a wet state until it is assembled into the electrolyzer stack.

This example provides a detailed methodology for the preparation and activation of a catalyst layer using a specific alloy composition. The process steps are designed to ensure the integrity and functionality of the catalyst layer, which is critical for its performance in an AEM electrolyzer system.

Example 5: AEM Electrolyzer System Assembly and Testing

In this final example, the system and methods of the present disclosure are employed in the assembly and testing of an AEM electrolyzer system. The system assembly begins with the preparation of the catalyst composition. The meso porous catalyst layer is applied to the porous transport layer on the anode side of the anion exchange membrane using either the spraying or decal process. The bipolar plates are aligned with the anion exchange membrane to form an integrated cell structure, and the membrane is conditioned in alkali-ion form prior to assembly.

The assembled AEM electrolyzer system may undergo a series of tests to evaluate gas purity and efficiency. Safety features are incorporated to prevent gas mixing, and the anion exchange membrane is sealed between the cathode and anode sides to prevent leakage. The flow of aqueous alkaline electrolyte through the system is optimized, and a precision coating technique is used to achieve the desired catalyst layer thickness. The system is then integrated with a power source and configured for modular scalability.

The AEM electrolyzer system may be calibrated for specific electrolysis applications, and a monitoring system is implemented to track performance. Automated assembly techniques are used for mass production, and environmental impact assessments are conducted. Renewable energy sources are incorporated into the operation of the system, and a final inspection process ensures compliance with industry standards. This example showcases the comprehensive application of the invention from assembly to testing, ensuring that the AEM electrolyzer system is efficient, safe, and environmentally friendly, as supported by the detailed descriptions set forth hereinabove.

Example embodiments are provided so that this disclosure will be thorough, and will fully convey the scope to those who are skilled in the art. Numerous specific details are set forth such as examples of specific components, devices, and methods, to provide a thorough understanding of embodiments of the present disclosure. It will be apparent to those skilled in the art that specific details need not be employed, that example embodiments may be embodied in many different forms, and that neither should be construed to limit the scope of the disclosure. In some example embodiments, well-known processes, well-known device structures, and well-known technologies are not described in detail. Equivalent changes, modifications and variations of some embodiments, materials, compositions and methods can be made within the scope of the present technology, with substantially similar results.