Porous assemblies, methods of fabrication thereof, and use thereof

Abstract

A porous assembly for use as an anode pack in an electrolyzer including a flow field configured to provide moisture to a proton exchange membrane of an electrolyzer, conduct heat away from the proton exchange membrane, and extract oxygen from the proton exchange membrane through the flow of water, the flow field having a thickness of 0.003 to 0.1" (0.08 to 2.54 mm), or 0.003 to 0.05" (0.08 to 1.27 mm); and a porous metallic layer having a thickness of 0.003 to 0.05" (0.08 to 1.27 mm) and a mean pore size of 0.2 to 20 pm on the flow field.

Description

POROUS ASSEMBLIES, METHODS OF FABRICATION THEREOF, AND USE THEREOF CROSS REFERENCE TO RELATED APPLICATION

[0001] This application claims the benefit of US Application No. 63 / 604,251, filed on November 30, 2023, which is incorporated herein by reference in its entirety. FIELD OF THE DISCLOSURE

[0002] The present disclosure relates to multi-layer porous assemblies and related methods of fabrication and use and, more particularly, to multi-layer porous assemblies including a flow field (e.g., for use in a fuel cell / electrolyzer / battery). BACKGROUND OF THE DISCLOSURE

[0003] In a method to produce hydrogen utilizing a proton exchange membrane (PEM) process, a polymeric material (such as NafionTM) can be present at the center of an electrolyzer. Hydrogen ions can pass through the polymeric PEM while the PEM membrane can block the passage of water and oxygen, which allows for separation of the two gases, hydrogen and oxygen, produced via electrolysis. The cathode assembly can contain a porous graphite layer in intimate contact with the PEM and a manifold that collects the hydrogen gas as the hydrogen gas passes through the graphite layer. The side of the electrolyzer opposite the cathode assembly across the PEM can be referred to as the anode pack and can contain a Membrane Transport Layer (MTL) and a flow field (series of channels or porous structure) that is used to supply water to the PEM to keep the PEM moist, provide cooling, and to extract oxygen. The MTL can be a very thin, porous titanium sheet.

[0004] An anode pack can be made by stacking starting with a non-porous titanium sheet. The flow field of the anode pack can be fabricated by assembling multiple separate / individual flow field layers (e.g., titanium screens / sintered metal porous metal media). Performance can be limited by the lack of flexibility in designing the pore structure and / or dimensions of screens forming the flow field.

[0005] A layer of thin micro-porous titanium can be stacked on the assembled flow field and the PEM can be placed on the micro-porous titanium sheet. The various layers of the sandwich structure can then be compresses together and inputs and outputs for water, hydrogen,and oxygen can be provided to the compressed structure. The efficiency of the fabricated electrolyzer can be directly related to the overall resistance of the sandwich structure, with better hydrogen production efficiency provided with lower overall cell electrical resistance.

[0006] An interest exists for improved multi-layer porous assemblies and related methods of fabrication and use. These and other inefficiencies and opportunities for improvement are addressed and / or overcome by the disclosed porous assemblies, systems and methods of the present disclosure. BRIEF SUMMARY OF THE DISCLOSURE

[0007] The present disclosure provides advantageous multi-layer porous assemblies, and improved systems / methods for utilizing and / or fabricating the multi-layer porous assemblies. More particularly, the present disclosure provides multi-layer porous assemblies including a flow field.

[0008] Provided is a porous assembly for use as an anode pack in an electrolyzer includes a flow field configured to provide moisture to a proton exchange membrane of an electrolyzer, conduct heat away from the proton exchange membrane, and extract oxygen from the proton exchange membrane through the flow of water, the flow field having a thickness of 0.003 to 0.1” (0.08 to 2.54 mm), or 0.003 to 0.05” (0.08 to 1.27 millimeters (mm)); and a porous metallic layer having a thickness of 0.003 to 0.05” (0.08 to 1.27 mm) and a mean pore size of 0.2 to 20 µm on the flow field.

[0009] The porous assembly can further include a support layer including a porous metal layer, wherein the metal includes titanium, nickel, or a combination thereof.

[0010] The flow field includes a metal layer can include through-holes, wherein the metal includes titanium, nickel, or a combination thereof.

[0011] The flow field can include a media grade 40 or higher metal sheet, wherein the metal includes titanium, nickel, or a combination thereof.

[0012] The flow field can include a media grade 20 or higher metal sheet, wherein the metal includes titanium, nickel, or a combination thereof.

[0013] The flow field can include a metal layer including channels, wherein the metal includes titanium, nickel, or a combination thereof.

[0014] The flow field can include a corrugated metal layer, wherein the metal includes titanium, nickel, or a combination thereof.

[0015] The flow field can include a dimpled metal layer, wherein the metal includes titanium, nickel, or a combination thereof, and wherein the flow field includes indentations in opposing sides of the dimpled metal layer.

[0016] The porous metallic layer can include grooves in a surface of the porous metallic layer facing the porous metallic layer.

[0017] The flow field can include more than one layer.

[0018] Provided is a fixture includes the porous assembly; and a non-porous metal layer, wherein the metal includes titanium, nickel, or a combination thereof.

[0019] Provided is a method for fabricating the porous assembly includes fabricating the flow field; and positioning a porous metallic layer on the flow field.

[0020] The flow field can be fabricated at least in part by additive manufacturing.

[0021] The flow field can be fabricated at least in part by a 3D printing process.

[0022] The method can further include fabricating the porous metallic layer by additive manufacturing.

[0023] The flow field can be fabricated at least in part by laser milling, chemically milling via photo lithography techniques, or a combination thereof.

[0024] The above described and other features are exemplified by the following figures and detailed description.

[0025] Any combination or permutation of embodiments is envisioned. Additional advantageous features, functions and applications of the disclosed assemblies, systems and methods of the present disclosure will be apparent from the description which follows, particularly when read in conjunction with the appended figures. All references listed in this disclosure are hereby incorporated by reference in their entireties. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The following figures are exemplary embodiments wherein the like elements are numbered alike.

[0027] Features and aspects of embodiments are described below with reference to the accompanying drawings, in which elements are not necessarily depicted to scale.

[0028] Exemplary embodiments of the present disclosure are further described with reference to the appended figures. It is to be noted that the various features, steps, and combinations of features / steps described below and illustrated in the figures can be arranged and organized differently to result in embodiments which are still within the scope of the present disclosure. To assist those of ordinary skill in the art in making and using the disclosed multi- layer porous assemblies, systems and methods, reference is made to the appended figures, wherein:

[0029] FIG. 1 is a schematic cross-sectional view of a porous assembly according to the present disclosure;

[0030] FIG. 2A is a perspective view of a flow field according to the present disclosure;

[0031] FIG. 2B is a perspective view of a flow field according to the present disclosure;

[0032] FIG. 2C is a perspective view of a flow field according to the present disclosure;

[0033] FIG. 3A is a perspective view of a porous assembly according to the present disclosure;

[0034] FIG. 3B is a perspective view of a porous assembly according to the present disclosure;

[0035] FIG. 3C is a perspective view of a porous assembly according to the present disclosure;

[0036] FIG. 4A is a perspective view of a flow field according to the present disclosure;

[0037] FIG. 4B is a perspective view of a flow field according to the present disclosure;

[0038] FIG. 4C is a perspective view of a flow field according to the present disclosure;

[0039] FIG. 5A is a perspective view of a porous assembly according to the present disclosure;

[0040] FIG. 5B is a perspective view of a porous assembly according to the present disclosure;

[0041] FIG. 5C is a perspective view of a porous assembly according to the present disclosure;

[0042] FIG. 6 is a schematic cross-sectional view of a porous assembly according to the present disclosure;

[0043] FIG. 7 is a schematic cross-sectional view of a porous assembly according to the present disclosure;

[0044] FIG. 8 is a schematic cross-sectional view of a porous assembly according to the present disclosure;

[0045] FIG. 9A is a schematic cross-sectional view of a porous assembly according to the present disclosure;

[0046] FIG. 9B is a schematic cross-sectional view of a porous assembly according to the present disclosure;

[0047] FIG. 10A is a perspective view of a flow field according to the present disclosure;

[0048] FIG. 10B is a perspective view of a flow field according to the present disclosure;

[0049] FIG. 10C is a perspective view of a flow field according to the present disclosure;

[0050] FIG. 11A is a perspective view of a porous assembly according to the present disclosure;

[0051] FIG. 11B is a perspective view of a porous assembly according to the present disclosure;

[0052] FIG. 11C is a perspective view of a porous assembly according to the present disclosure;

[0053] FIG. 12A is a perspective view of a porous assembly according to the present disclosure;

[0054] FIG. 12B is a perspective view of a flow field according to the present disclosure;

[0055] FIG. 12C is a perspective view of a flow field according to the present disclosure;

[0056] FIG. 13A is a perspective view of a porous assembly according to the present disclosure;

[0057] FIG. 13B is a perspective view of a porous assembly according to the present disclosure;

[0058] FIG. 13C is a perspective view of a porous assembly according to the present disclosure;

[0059] FIG. 14 is a schematic cross-sectional view of a porous assembly according to the present disclosure;

[0060] FIG. 15 is a schematic cross-sectional view of a porous assembly according to the present disclosure;

[0061] FIG. 16 is a schematic cross-sectional view of a porous assembly according to the present disclosure;

[0062] FIG. 17 is a schematic cross-sectional view of a porous assembly according to the present disclosure; and

[0063] FIG. 18A is a perspective view of a pleated, porous titanium layer according to the present disclosure;

[0064] FIG. 18B is a perspective view of a pleated, porous titanium layer according to the present disclosure;

[0065] FIG. 18C is a perspective view of a pleated, porous titanium layer according to the present disclosure;

[0066] FIG. 19A is a perspective view of a porous assembly according to the present disclosure;

[0067] FIG. 19B is a perspective view of a porous assembly according to the present disclosure;

[0068] FIG. 19C is a perspective view of a porous assembly according to the present disclosure;

[0069] FIG. 20 is a schematic cross-sectional view of a porous assembly according to the present disclosure;

[0070] FIG. 21A is a perspective view of a dimpled metal layer according to the present disclosure;

[0071] FIG. 21B is a perspective view of a dimpled metal layer according to the present disclosure;

[0072] FIG. 21C is a perspective view of a dimpled metal layer according to the present disclosure;

[0073] FIG. 22A is a perspective view of a dimpled metal layer according to the present disclosure;

[0074] FIG. 22B is a perspective view of a dimpled metal layer according to the present disclosure;

[0075] FIG. 22C is a perspective view of a dimpled metal layer according to the present disclosure;

[0076] FIG. 23A is a perspective view of a porous assembly according to the present disclosure;

[0077] FIG. 23B is a perspective view of a porous assembly according to the present disclosure;

[0078] FIG. 23C is a perspective view of a porous assembly according to the present disclosure;

[0079] FIG. 24A is a perspective view of flow channels according to the present disclosure;

[0080] FIG. 24B is a perspective view of flow channels according to the present disclosure;

[0081] FIG. 24C is a perspective view of flow channels according to the present disclosure;

[0082] FIG. 25A is a perspective view of a porous assembly according to the present disclosure;

[0083] FIG. 25B is a perspective view of a porous assembly according to the present disclosure;

[0084] FIG. 25C is a perspective view of a porous assembly according to the present disclosure;

[0085] FIG. 26A is a perspective view of flow channels according to the present disclosure;

[0086] FIG. 26B is a perspective view of flow channels according to the present disclosure;

[0087] FIG. 26C is a perspective view of flow channels according to the present disclosure;

[0088] FIG. 27A is a perspective view of a porous assembly according to the present disclosure;

[0089] FIG. 27B is a perspective view of a porous assembly according to the present disclosure;

[0090] FIG. 27C is a perspective view of a porous assembly according to the present disclosure;

[0091] FIG. 28A is an angled view of a porous assembly according to the present disclosure;

[0092] FIG. 28B is an angled view of a porous assembly according to the present disclosure;

[0093] FIG. 28C is an edge view of a porous assembly according to the present disclosure;

[0094] FIG. 29 is a graph of resistance versus applied pressure for various porous assemblies;

[0095] FIG. 30 is a graph of resistance versus applied pressure for various porous assemblies; and

[0096] FIG. 31 is a graph of pressure drop versus water flow for various porous assemblies. DETAILED DESCRIPTION OF THE DISCLOSURE

[0097] The exemplary embodiments disclosed herein are illustrative of advantageous porous assemblies (also referred to herein as multi-layer porous assemblies), and systems of the present disclosure and methods / techniques thereof. It should be understood, however, that the disclosed embodiments are merely exemplary of the present disclosure, which may be embodied in various forms. Therefore, details disclosed herein with reference to exemplary porous assemblies and associated processes / techniques of fabrication / assembly and use are not to be interpreted as limiting, but merely as the basis for teaching one skilled in the art how to make and use the advantageous porous assemblies and / or alternative porous assemblies of the present disclosure.

[0098] The present disclosure provides advantageous porous assemblies, and improved systems / methods for utilizing and / or fabricating the porous assemblies.

[0099] Referring now to the drawings, like parts are marked throughout the specification and drawings with the same reference numerals, respectively. Drawing figures are not necessarily to scale and in certain views, parts may have been exaggerated for purposes of clarity.

[0100] A myriad geometries for the flow field of the porous assembly are possible (e.g., circles, squares, odd shapes, etc.). The present disclosure provides that the flow field can be fabricated utilizing a host of materials (e.g., metals, polymers, etc.). Disclosed dimensions (e.g., feature dimensions) can be adjusted for the size of the electrolyzer desired (e.g., depending onthe overall width and length of the porous assembly), to meet the flow and cooling preferences for a given application, or a combination thereof.

[0101] The material of construction can be titanium but other materials compatible for electrolysis applications can be used, such as nickel, stainless steel, and alloys compatible to electrolyzer processes. As used herein, “metal” refers to a suitable material of construction such as titanium, nickel, or a combination thereof. Such metals have a relatively high corrosion resistance, as compared to, for example, copper, iron, brass, and zinc. The titanium can be or Titanium Grade 1 or Titanium Grade 2; Ti64, including vanadium, may not provide sufficient corrosion resistance. The disclosed materials and methods of construction can result in metallurgical diffusion bonds that can resist corrosion, in comparison to laminated materials that can be present in other methods of construction and subject to corrosion.

[0102] The overall dimensions and shape of the porous assemblies can vary depending on the application. For example, the porous assemblies can be circular or square or rectangular. For small test cells, 3” (76.2 mm) diameter or 4” (101.6 mm) square porous assemblies can be used. For larger hydrogen production applications, 8” (203.2 mm) or 12” (304.8 mm) circular porous assemblies can be used as well as rectangular porous assemblies with dimensions exceeding 12” x 24” (304.8 mm x 609.6 mm).

[0103] The thickness of the porous assemblies can vary from 0.03 to greater than 0.2” (0.76 to greater than 5.08 mm) with an exemplary thickness of, for example, 0.05 to 0.1” (1.27 to 2.54 mm) or 0.075” (1.905 mm). The porous assemblies include a porous metallic layer and a flow field and can also include additional optional layers.

[0104] With reference to FIG. 1, FIG. 6, FIG. 7, FIG. 8, FIG. 9A, FIG. 9B, FIG. 14, FIG. 15, FIG. 16, FIG. 17, and FIG. 20, as the disclosed porous assemblies include a porous metallic layer 1, flow through the porous assemblies is not limited to the flow field layer, which is shown in the figures and referenced herein as layer 3. Rather, flow through the porous assemblies can also occur through the porous metallic layer(s) 1. Such additional flow can provide, for example, improved cooling and oxygen extraction.

[0105] Unless otherwise specified, the porous metallic layer 1 includes or is a porous metal layer having a maximum thickness of 0.003 to 0.05” (0.08 to 1.27 mm) or 0.005 to 0.01” (0.13 to 0.25 mm) and a mean pore size of, for example, 0.2 to 10 µm, or 2 µm. For example, theporous metallic layer 1 can be 0.01” (0.25 mm) thick with hole diameters of 0.00039” (0.01 mm) and hole spacing of 0.00039” (0.01 mm).

[0106] The flow field can take various forms as described herein, such as, for example, a metal sheet, e.g., a media grade 20 or higher metal sheet or media grade 40 or higher metal sheet, optionally including through-holes, non-through holes, grooves, channels (e.g., with a linear or rectangular cross-section), indentations, or a combination thereof. The flow field, for example, including through-holes, non-through holes, grooves, channels, indentations, or a combination thereof, allows for a flow of water to provide moisture to a proton exchange membrane of an electrolyzer, conduct heat away from the proton exchange membrane, and extract oxygen from the proton exchange membrane.

[0107] The optional layer(s) can include, for example, a support layer 2. Unless otherwise specified, the support layer 2 includes or is a porous metal layer having a thickness of 0.003 to 0.05” (0.08 to 1.27 mm), or 0.004 to 0.02” (0.10 to 0.51 mm), or 0.005 to 0.01” (0.13 to 0.25 mm) and a mean pore size of, for example, 1 to 30 µm, 5 to 20 µm, or 10 µm.

[0108] A fixture housing the electrolysis cell further can include a backing layer that can include or be a non-porous metal layer with a thickness adjusted to meet fixturing preferences. A thickness of the backing layer can vary from 0.01 to 0.03” (0.25 to 0.76 mm).

[0109] After the individual layers are fabricated, the individual layers can then be stacked and placed in a vacuum furnace under a compressive load and diffusion bonded at a temperature and time suitable to diffusion bond metal. Diffusion bonding can provide the metallurgical interface bonds to assure a low electrical resistance for the porous assembly and good corrosion resistance. The thickness of the porous assembly can be thinner, for example, 0.03 to 0.2” (0.76 to 5.08 mm), 0.04 to 0.1” (1.02 to 2.54 mm), or 0.05” (1.27 mm). Diffusion bonding can also allow for lower levels of coating including platinum group metals (PGM) (such as platinum (Pt), palladium (Pd), rhodium (Rh), or a combination thereof) that can be included in assemblies to prevent passivation. For example, anti-passivation PGM coating levels can be reduced by about 50 weight percent or greater in bonded assemblies as compared to unbonded or electroplated assemblies.

[0110] With reference to FIG. 1, layer 3 includes or is a series of through-holes extending from a first surface of layer 3 to a second, opposite surface of layer 3. The through-holes can be formed in a non-porous metal layer or from a porous metal layer having a thickness of, forexample, 0.003 to 0.1” (0.08 to 2.54 mm), 0.003 to 0.05” (0.08 to 1.27 mm), 0.005 to 0.03” (0.13 to 0.76 mm), or 0.02” (0.51 mm) or greater. The through-hole widths can vary from 0.5 to 1 mm and extend across the width of the porous assembly.

[0111] With further reference to FIG. 1, as stated above, the porous metallic layer 1 can include or be a porous metal layer having a maximum thickness of 0.003 to 0.05” (0.08 to 1.27 mm) or 0.005 to 0.01” (0.13 to 0.25 mm) and a mean pore size of, for example, 0.2 to 10 µm, or 2 µm. For example, the porous metallic layer 1 can be 0.01” (0.25 mm) thick with hole diameters of 0.00039” (0.01 mm) and hole spacing of 0.00039” (0.01 mm). While shown in FIG. 1, support layer 2 is optional. If present, the support layer 2 can include or be a porous metal layer having a thickness of 0.003 to 0.05” (0.08 to 1.27 mm), or 0.004 to 0.02” (0.10 to 0.51 mm), or 0.005 to 0.01” (0.13 to 0.25 mm) and a mean pore size of, for example, 1 to 30 µm, 5 to 20 µm, or 10 µm.

[0112] Each of FIG. 2A, FIG. 2B, and FIG. 2C is a perspective view of relatively shallow flow channels extending in one direction parallel to an edge of a support layer. The flow channels are defined by titanium structures extending from the support layer. The support layer is solid titanium and the raised sections are porous. The depth of the flow channels are about 0.75 mm with a width of about 0.75 mm. The thickness of the solid support layer is about 0.75 mm.

[0113] Each of FIG. 3A, FIG. 3B, and FIG. 3C is a perspective view of a porous assembly, e.g., anode pack, made from the structure shown in FIG. 2A, FIG. 2B, and FIG. 2C. The anode pack dimensions are 4” x 4” (101.6 mm x 101.6 mm) with a total thickness of 1.75 mm.

[0114] Flow channel widths and depths can range from about 0.1 mm to 2 mm. The titanium structures defining the flow channels are porous with a density of about 40% and a mean pore size of about 60 µm. The density and pore size can vary from 40% to 90% dense with mean pore sizes from 0.5 µm to about 60 µm.

[0115] Each of FIG. 4A, FIG. 4B, and FIG. 4C is a perspective view of relatively deep flow extending in one direction parallel to an edge of a support layer. The flow channels are defined by titanium structures extending from the support layer. The support layer is solid titanium and the raised sections are porous. The depth of the flow channels are about 1.5 mm with a width of about 0.75 mm. The thickness of the solid support layer is about 0.75 mm.

[0116] Each of FIG. 5A, FIG. 5B, and FIG. 5C is a perspective view of a porous assembly, e.g., anode pack, made from the structure shown in FIG. 4A, FIG. 4B, and FIG. 4C. The anode pack dimensions are 4” x 4” (101.6 mm x 101.6 mm) with a total thickness of 2.25 mm.

[0117] Flow channel widths and depths can range from about 0.1 mm to 2 mm. The titanium structures defining the flow channels are porous with a density of about 40% and a mean pore size of about 60 µm. The density and pore size can vary from 40% to 90% dense with mean pore sizes from 0.5 µm to about 60 µm.

[0118] With reference to FIG. 6, layer 3 is a metal layer having a pore size between 100 and 200 µm and thickness of, for example, 0.003 to 0.1” (0.08 to 2.54 mm), 0.003 to 0.05” (0.08 to 1.27 mm), 0.005 to 0.04” (0.13 to 1.02 mm), or 0.03” (0.76 mm) or greater.

[0119] With further reference to FIG. 6, as stated above, the porous metallic layer 1 can include or be a porous metal layer having a maximum thickness of 0.003 to 0.05” (0.08 to 1.27 mm) or 0.005 to 0.01” (0.13 to 0.25 mm) and a mean pore size of, for example, 0.2 to 10 µm, or 2 µm. For example, the porous metallic layer 1 can be 0.01” (0.25 mm) thick with hole diameters of 0.00039” (0.01 mm) and hole spacing of 0.00039” (0.01 mm). While shown in FIG. 6, support layer 2 is optional. If present, the support layer 2 can include or be a porous metal layer having a thickness of 0.003 to 0.05” (0.08 to 1.27 mm), or 0.004 to 0.02” (0.10 to 0.51 mm), or 0.005 to 0.01” (0.13 to 0.25 mm) and a mean pore size of, for example, 1 to 30 µm, 5 to 20 µm, or 10 µm.

[0120] FIG. 7 is similar to FIG. 1, with the porous metallic layer 1 having a smooth outer surface and a surface adjacent to support layer 2 having channels extending across the width of the structure. The porous metallic layer 1 described with reference to FIG. 7 can be included as the porous metallic layer 1 in porous assemblies described with reference to other figures herein. Layer 3 includes or is a series of through-holes extending from a first surface of layer 3 to a second, opposite surface of layer 3. The through-holes can be formed in a non-porous metal layer or from a porous metal layer having a thickness of, for example, 0.003 to 0.1” (0.08 to 2.54 mm), 0.003 to 0.05” (0.08 to 1.27 mm), 0.005 to 0.03” (0.13 to 0.76 mm), or 0.02” (0.51 mm) or greater. The through-hole widths can vary from 0.5 to 1 mm and extend across the width of the porous assembly.

[0121] With further reference to FIG. 7, as stated above, the porous metallic layer 1 can include or be a porous metal layer having a maximum thickness of 0.003 to 0.05” (0.08 to 1.27mm) or 0.005 to 0.01” (0.13 to 0.25 mm) and a mean pore size of, for example, 0.2 to 10 µm, or 2 µm. For example, the porous metallic layer 1 can be 0.01” (0.25 mm) thick with hole diameters of 0.00039” (0.01 mm) and hole spacing of 0.00039” (0.01 mm). While shown in FIG. 7, support layer 2 is optional. If present, the support layer 2 can include or be a porous metal layer having a thickness of 0.003 to 0.05” (0.08 to 1.27 mm), or 0.004 to 0.02” (0.10 to 0.51 mm), or 0.005 to 0.01” (0.13 to 0.25 mm) and a mean pore size of, for example, 1 to 30 µm, 5 to 20 µm, or 10 µm.

[0122] FIG. 8 is similar to FIG. 1 with the difference being the addition of an additional layer 2a between porous metallic layer 1 and support layer 2. With reference to FIG. 8, additional layer 2a is made from either a non-porous metal layer or porous metal layer having a thickness of, for example, 0.003 to 0.05” (0. 0.08 to 1.27 mm), 0.005 to 0.03” (0.13 to 0.76 mm), or 0.01” (0.25 mm). The layer can be perforated with through holes with diameters ranging from 10 to 100 µm or 25 to 100 µm with comparable spacing dimensions between the holes. The holes can follow a rectangular grid pattern or a close packed pattern. The holes can be machined through the layer utilizing micro drilling methods, laser drilling, or by use of photolithography / etching techniques. The additional layer 2a described with reference to FIG. 8 can be included in porous assemblies described with reference to other figures herein.

[0123] Layer 3 includes or is a series of through-holes extending from a first surface of layer 3 to a second, opposite surface of layer 3. The through-holes can be formed in a non-porous metal layer or from a porous metal layer having a thickness of, for example, 0.003 to 0.1” (0.08 to 2.54 mm), 0.003 to 0.05” (0.08 to 1.27 mm), 0.005 to 0.03” (0.13 to 0.76 mm), or 0.02” (0.51 mm) or greater. The through-hole widths can vary from 0.5 to 1 mm and extend across the width of the porous assembly.

[0124] With further reference to FIG. 8, as stated above, the porous metallic layer 1 can include or be a porous metal layer having a maximum thickness of 0.003 to 0.05” (0.08 to 1.27 mm) or 0.005 to 0.01” (0.13 to 0.25 mm) and a mean pore size of, for example, 0.2 to 10 µm, or 2 µm. For example, the porous metallic layer 1 can be 0.01” (0.25 mm) thick with hole diameters of 0.00039” (0.01 mm) and hole spacing of 0.00039” (0.01 mm). While shown in FIG. 8, each of support layer 2 and additional layer 2a is optional. If present, the support layer 2 can include or be a porous metal layer having a thickness of 0.003 to 0.05” (0.08 to 1.27 mm), or 0.004 to 0.02” (0.10 to 0.51 mm), or 0.005 to 0.01” (0.13 to 0.25 mm) and a mean pore size of, for example, 1 to 30 µm, 5 to 20 µm, or 10 µm.

[0125] With reference to FIG. 9A, layer 3 includes or is made from a porous metal layer having a mean pore size between 20 and 40 µm with a series of grooves formed in outer surfaces of layer 3. The shape of the grooves can be rounded (e.g., semicircular cross-section), v-grooves, or have flat rectilinear, e.g., square, bottoms. The thickness of layer 3 can be, for example, 0.003 to 0.1” (0.08 to 2.54 mm), 0.003 to 0.05” (0.08 to 1.27 mm), 0.005 to 0.03” (0.13 to 0.76 mm), or 0.015” (0.381 mm). The groove widths and depths can vary from 0.5 to 1 mm and extend across the width of the porous assembly.

[0126] With further reference to FIG. 9A, as stated above, the porous metallic layer 1 can include or be a porous metal layer having a maximum thickness of 0.003 to 0.05” (0.08 to 1.27 mm) or 0.005 to 0.01” (0.13 to 0.25 mm) and a mean pore size of, for example, 0.2 to 10 µm, or 2 µm. For example, the porous metallic layer 1 can be 0.01” (0.25 mm) thick with hole diameters of 0.00039” (0.01 mm) and hole spacing of 0.00039” (0.01 mm). While shown in FIG. 9A, support layer 2 is optional. If present, the support layer 2 can include or be a porous metal layer having a thickness of 0.003 to 0.05” (0.08 to 1.27 mm), or 0.004 to 0.02” (0.10 to 0.51 mm), or 0.005 to 0.01” (0.13 to 0.25 mm) and a mean pore size of, for example, 1 to 30 µm, 5 to 20 µm, or 10 µm.

[0127] With reference to FIG. 9B, the layer 3 can include two portions (3a and 3b), with a series of grooves formed in a surface of each of the portions. The portions can then be arranged such that the surface of each of the portions containing the grooves are adjacent to one another. A groove in a surface of a first portion and an adjacent groove in a surface of a second portion can form a flow path that is semicircular, wedge shaped, or rectilinear, e.g., square.

[0128] With further reference to FIG. 9B, as stated above, the porous metallic layer 1 can include or be a porous metal layer having a maximum thickness of 0.003 to 0.05” (0.08 to 1.27 mm) or 0.005 to 0.01” (0.13 to 0.25 mm) and a mean pore size of, for example, 0.2 to 10 µm, or 2 µm. For example, the porous metallic layer 1 can be 0.01” (0.25 mm) thick with hole diameters of 0.00039” (0.01 mm) and hole spacing of 0.00039” (0.01 mm). While shown in FIG. 9B, support layer 2 is optional. If present, the support layer 2 can include or be a porous metal layer having a thickness of 0.003 to 0.05” (0.08 to 1.27 mm), or 0.004 to 0.02” (0.10 to 0.51 mm), or 0.005 to 0.01” (0.13 to 0.25 mm) and a mean pore size of, for example, 1 to 30 µm, 5 to 20 µm, or 10 µm.

[0129] Each of FIG. 10A, FIG. 10B, and FIG. 10C is a perspective view of relative thin capillary flow channels extending in one direction parallel to an edge of a support layer. The open capillary flow channels are present in a porous titanium layer. The diameter of the capillaries are about 0.75 mm with a spacing of about 1.5 mm between.

[0130] Each of FIG. 11A, FIG. 11B, and FIG. 11C is a perspective view of a porous assembly, e.g., anode pack, made from the structure shown in FIG. 10A, FIG. 10B, and FIG. 10C. The anode pack dimensions were 4” x 4” (101.6 mm x 101.6 mm) x 1.75 mm.

[0131] Capillary diameters can vary from about 0.1 mm to 2 mm depending on the thickness of the anode pack. The porous titanium layer defining the capillaries has a density of about 40% and a mean pores size of about 60 µm. The density and pores size of this plate can vary from 40% to 90% dense with mean pores sizes from 0.5 µm to about 60 µm.

[0132] Each of FIG. 12A, FIG. 12B, and FIG. 12C is a perspective view of relative thick capillary flow channels extending in one direction parallel to an edge of a support layer. The open capillary flow channels are present in a porous titanium layer. The diameter of the capillaries are about 0.75 mm with a spacing of about 1.5 mm between.

[0133] Each of FIG. 13A, FIG. 13B, and FIG. 13C is a perspective view of a porous assembly, e.g., anode pack, made from the structure shown in FIG. 12A, FIG. 12B, and FIG. 12C. The anode pack dimensions were 4” x 4” (101.6 mm x 101.6 mm) x 2.2 mm.

[0134] Capillary diameters can vary from about 0.1 mm to 2 mm depending on the thickness of the anode pack. The porous titanium layer defining the capillaries has a density of about 50% and a mean pores size of about 40 µm. The density and pores size of this plate can vary from 40% to 90% dense with mean pores sizes from 0.5 µm to about 60 µm.

[0135] With reference to FIG. 14, layer 3 includes or is a series of channels on first and second opposite surfaces of layer 3. The flow channels can be formed in a porous metal layer having a thickness of, for example, 0.003 to 0.1” (0.08 to 2.54 mm), 0.003 to 0.05” (0.08 to 1.27 mm), 0.005 to 0.03” (0.13 to 0.76 mm), or 0.01” (0.25 mm) or greater. The flow channel widths can vary from 0.5 to 1 mm and extend across the width of the porous assembly.

[0136] With further reference to FIG. 14, as stated above, the porous metallic layer 1 can include or be a porous metal layer having a maximum thickness of 0.003 to 0.05” (0.08 to 1.27 mm) or 0.005 to 0.01” (0.13 to 0.25 mm) and a mean pore size of, for example, 0.2 to 10 µm, or 2 µm. For example, the porous metallic layer 1 can be 0.01” (0.25 mm) thick with hole diametersof 0.00039” (0.01 mm) and hole spacing of 0.00039” (0.01 mm). While shown in FIG. 14, support layer 2 is optional. If present, the support layer 2 can include or be a porous metal layer having a thickness of 0.003 to 0.05” (0.08 to 1.27 mm), or 0.004 to 0.02” (0.10 to 0.51 mm), or 0.005 to 0.01” (0.13 to 0.25 mm) and a mean pore size of, for example, 1 to 30 µm, 5 to 20 µm, or 10 µm.

[0137] FIG. 15 is similar to FIG. 14, but porous metallic layer 1 includes or is a single layer of porous metal layer having a mean pores size of 2 µm and a thickness from 0.005 to 0.04” (0.13 to 1.02 mm) and support layer 2 shown in FIG. 14 is omitted.

[0138] With further reference to FIG. 15, as stated above, the porous metallic layer 1 can include or be a porous metal layer having a maximum thickness of 0.003 to 0.05” (0.08 to 1.27 mm) or 0.005 to 0.01” (0.13 to 0.25 mm) and a mean pore size of, for example, 0.2 to 10 µm, or 2 µm. For example, the porous metallic layer 1 can be 0.01” (0.25 mm) thick with hole diameters of 0.00039” (0.01 mm) and hole spacing of 0.00039” (0.01 mm). While not shown in FIG. 15, support layer 2 can be present. If present, the support layer 2 can include or be a porous metal layer having a thickness of 0.003 to 0.05” (0.08 to 1.27 mm), or 0.004 to 0.02” (0.10 to 0.51 mm), or 0.005 to 0.01” (0.13 to 0.25 mm) and a mean pore size of, for example, 1 to 30 µm, 5 to 20 µm, or 10 µm.

[0139] FIG. 16 is similar to FIG. 14, but porous metallic layer 1 includes or is made from a porous metal layer having a mean pore size of 2 µm and having a smooth outer surface and a surface adjacent to support layer 2 having channels extending across the width of the structure. The thickness of porous metallic layer 1 can be between 0.005” (0.13 mm) and 0.01” (0.25 mm). The porous metallic layer 1 described with reference to FIG. 16 can be included as the porous metallic layer 1 in porous assemblies described with reference to other figures herein.

[0140] With further reference to FIG. 16, as stated above, the porous metallic layer 1 can include or be a porous metal layer having a maximum thickness of 0.003 to 0.05” (0.08 to 1.27 mm) or 0.005 to 0.01” (0.13 to 0.25 mm) and a mean pore size of, for example, 0.2 to 10 µm, or 2 µm. For example, the porous metallic layer 1 can be 0.01” (0.25 mm) thick with hole diameters of 0.00039” (0.01 mm) and hole spacing of 0.00039” (0.01 mm). While shown in FIG. 16, support layer 2 is optional. If present, the support layer 2 can include or be a porous metal layer having a thickness of 0.003 to 0.05” (0.08 to 1.27 mm), or 0.004 to 0.02” (0.10 to 0.51 mm), or0.005 to 0.01” (0.13 to 0.25 mm) and a mean pore size of, for example, 1 to 30 µm, 5 to 20 µm, or 10 µm.

[0141] With reference to FIG. 17, layer 3 includes or is a series of channels and can be fabricated by pleating a metal layer to a variety of configurations. The pleating shown in FIG. 17 is in a sawtooth pattern and can be formed using a barrel pleater or stamping die. The shape of the pleats can be sawtooth as shown, sinusoidal, or square tooth patterns. The thickness of the layer from which the pleats are made can be 0.01” (0.25 mm) and the layer can be porous metal or made from a perforated metal layer. The pleat widths can vary from 0.5 to 1 mm and extend across the width of the porous assembly. The layer thickness can be, for example, 0.003 to 0.1” (0.08 to 2.54 mm), 0.003 to 0.05” (0.08 to 1.27 mm), 0.005 to 0.03” (0.13 to 0.76 mm), or 0.02” (0.51 mm) or greater.

[0142] With further reference to FIG. 17, as stated above, the porous metallic layer 1 can include or be a porous metal layer having a maximum thickness of 0.003 to 0.05” (0.08 to 1.27 mm) or 0.005 to 0.01” (0.13 to 0.25 mm) and a mean pore size of, for example, 0.2 to 10 µm, or 2 µm. For example, the porous metallic layer 1 can be 0.01” (0.25 mm) thick with hole diameters of 0.00039” (0.01 mm) and hole spacing of 0.00039” (0.01 mm). While shown in FIG. 17, support layer 2 is optional. If present, the support layer 2 can include or be a porous metal layer having a thickness of 0.003 to 0.05” (0.08 to 1.27 mm), or 0.004 to 0.02” (0.10 to 0.51 mm), or 0.005 to 0.01” (0.13 to 0.25 mm) and a mean pore size of, for example, 1 to 30 µm, 5 to 20 µm, or 10 µm.

[0143] Each of FIG. 18A, FIG. 18B, and FIG. 18C is a perspective view of a pleated, porous titanium layer. The pleats about 0.025” (0.6 mm) high with pleat-to-pleat spacing of about 0.1” (2.54 mm). The pleats were formed using a pleating mill.

[0144] Each of FIG. 19A, FIG. 19B, and FIG. 19C is a perspective view of a porous assembly, e.g., anode pack, made from the structure shown in FIG. 18A, FIG. 18B, and FIG. 18C. The anode pack was 4” x 4” (101.6 mm x 101.6 mm) and the total thickness was about 0.035” (0.7 mm). The width of the pleats were about 0.1” (2.54 mm), the height of the pleats were about 0.015” (0.381 mm), and a height of triangular flow channels after sinter bonding was about 0.005” (0.13 mm).

[0145] The flow through the anode pack is along a length of the pleats, e.g., across the width of the anode pack. One of the titanium layers can be a porous titanium layer having athickness from 0.005” (0.13 mm) to about 0.04” (1.02 mm) and the other of the titanium layers can be porous or solid or not included.

[0146] With reference to FIG. 20, layer 3 is fabricated by passing a porous metal layer through a dimple machine to create an array of bumps on a first surface of the layer and depressions on an opposite surface of the layer at corresponding locations. The bumps protrude from the surface 0.01” (0.25 mm) and are spaced in an array (grid or close packed) with spacings between them of, for example, 0.03 to 0.2” (0.76 to 5.08 mm), 0.04 to 0.1” (1.02 to 2.54 mm), or 0.05” (1.27 mm). A second dimpled layer can create more flow paths for fluid flow and cooling and can be repeated. The layer 3 can optionally include a second layer not including an array of bumps on a first surface of the layer and depressions on an opposite surface of the layer at corresponding locations.

[0147] With further reference to FIG. 20, as stated above, the porous metallic layer 1 can include or be a porous metal layer having a maximum thickness of 0.003 to 0.05” (0.08 to 1.27 mm) or 0.005 to 0.01” (0.13 to 0.25 mm) and a mean pore size of, for example, 0.2 to 10 µm, or 2 µm. For example, the porous metallic layer 1 can be 0.01” (0.25 mm) thick with hole diameters of 0.00039” (0.01 mm) and hole spacing of 0.00039” (0.01 mm). While shown in FIG. 20, support layer 2 is optional. If present, the support layer 2 can include or be a porous metal layer having a thickness of 0.003 to 0.05” (0.08 to 1.27 mm), or 0.004 to 0.02” (0.10 to 0.51 mm), or 0.005 to 0.01” (0.13 to 0.25 mm) and a mean pore size of, for example, 1 to 30 µm, 5 to 20 µm, or 10 µm.

[0148] Each of FIG. 21A, FIG. 21B, and FIG. 21C is a perspective view of a dimpled titanium layer showing bumps thereof. The height of the bumps are about 0.25” (6.35 mm) with spacing distances between the dimples of about 0.15” (3.81 mm). The dimples were pressed into the titanium layer using a rolling mill with dimpled rollers.

[0149] A knurling tool can be used to create a roughened surface on the porous layer and provide a flow path adjacent a layer. Knurled structures on a porous or non-porous layer can be created by using a stamping tool or textured rollers.

[0150] Each of FIG. 22A, FIG. 22B, and FIG. 22C is a perspective view of a dimpled titanium layer showing dimples, which correspond to the bumps on an opposite side of the titanium layer. Each side can include both dimples and bumps.

[0151] Each of FIG. 23A, FIG. 23B, and FIG. 23C is a perspective view of a porous assembly, e.g., anode pack, including 0.01” (0.25 mm) thick titanium layers and a dimpled porous titanium layer. A height of the flow channels is about 0.02” (0.51 mm) after sinter bonding of the layers. The flow through the anode pack, e.g., between the layers, is among and around the bumps between the porous titanium layers. The anode pack dimensions were 4” x 4” (101.6 mm x 101.6 mm) and the total thickness was about 0.04” (1.02 mm). Bump heights can range from about 0. 01 to 0.1” (0.254 to 2.54 mm), 0.01 to 0.05” (0.254 mm to 1.27 mm) with the spacing between the bumps either increased or decreased as desired. One of the titanium layers can be a porous titanium layer having a thickness from 0.005” (0.13 mm) to about 0.04” (1.02 mm) and the other of the titanium layers can be porous or solid or not included.

[0152] Each of FIG. 24A, FIG. 24B, and FIG. 24C is a perspective view of flow channels extending parallel to the edges of a support layer. The flow channels are defined by titanium protrusions extending from the support layer. The protrusions defining the flow channels are about 60% dense and the support layer is solid.

[0153] Each of FIG. 25A, FIG. 25B, and FIG. 25C is a perspective view of a porous assembly, e.g., anode pack, made from the structure shown in FIG. 24A, FIG. 24B, and FIG. 24C. The height of the protrusions were 1.2 mm and the support layer was 1 mm thick. The width of the flow channels was about 1 mm and the width of the protrusions were about 1.5 mm. Flow channel widths and feature heights can range from about 0.1 mm to 3 mm. The anode pack dimensions were 4” x 4” (101.6 mm x 101.6 mm) x 0.1”. The backing layer can be solid or porous with a density ranging from solid to about 50%. Sizes of interconnected pores can range from 0.5 µm to 40 µm.

[0154] Each of FIG. 26A, FIG. 26B, and FIG. 26C is a perspective view of flow channels extending 45 degrees relative to edges of a support layer. The flow channels are defined by titanium protrusions extending from the support layer. The protrusions defining the flow channels are about 60% dense and the support layer is solid.

[0155] Each of FIG. 27A, FIG. 27B, and FIG. 27C is a perspective view of a porous assembly, e.g., anode pack, made from the structure shown in FIG. 26A, FIG. 26B, and FIG. 26C. The height of the protrusions were 1.2 mm and the support layer was 1 mm thick. The width of the flow channels was about 1 mm and the width of the protrusions were about 1.5 mm.Flow channel widths and feature heights can range from about 0.1 mm to 3 mm. The anode pack dimensions were 4” x 4” (101.6 mm x 101.6 mm) x 0.1” (2.54 mm).

[0156] The backing layer can be solid or porous with a density ranging from solid to about 50%. Sizes of interconnected pores can range from 0.5 µm to 40 µm. Water flow follow a more torturous path from edge to edge providing a more uniform flow distribution across the anode pack.

[0157] With reference to FIG. 28A, FIG. 28B, and FIG. 28C, a flow field can be formed using metal, e.g., titanium, spheres in a close packed arrangement. The layer of metal spheres can be sandwiched between porous metallic layers to form a porous assembly, e.g., anode pack. FIG. 28A is a high magnification 45 degree angle view of such a porous assembly, FIG. 28B is a lower magnification 45 degree angle view of such a porous assembly, and FIG. 28C is an edge view of such a porous assembly. In FIG. 28A, FIG. 28B, and FIG. 28C, the top layer shown is a 0.01” (0.25 mm) thick porous titanium layer and the bottom layer shown in a 0.03” (0.76 mm) thick solid titanium layer. The overall thickness was 2 x 2 x 0.08” (50.8 x 50.8 x 2.03 mm).

[0158] The present disclosure provides for a multi-layer porous assembly including a flow field; and a porous metallic layer on the flow field. The flow field can be fabricated at least in part by additive manufacturing (e.g., via a 3D printing process, such as, for example, via an electron-beam additive manufacturing process, via a laser additive manufacturing technology, via an inkjet or a binder-jet additive manufacturing process, etc.). Other additive manufacturing processes can be utilized for the flow field (e.g., a fused deposition modeling (“FDM”) process; utilizing laser additive manufacturing technology (“LAMT”), etc.).

[0159] The present disclosure also provides for a method for fabricating a multi-layer porous assembly including providing a flow field; and positioning a porous metallic layer on the flow field. The flow field can be fabricated at least in part by additive manufacturing.

[0160] The present disclosure also provides for a method for fabricating a multi-layer porous assembly wherein the flow field can be fabricated at least in part by a 3D printing process.

[0161] The present disclosure also provides for a method for fabricating a multi-layer porous assembly wherein the flow field can be fabricated at least in part by an electron-beam additive manufacturing process or a laser additive manufacturing process.

[0162] A porous assembly, e.g., anode pack, can be made sinter bonding a flow field as disclosed and illustrated herein to a porous titanium layer, for example, having a thickness of 0.01” (0.254 mm) and a density of about 60%. Various combinations of additive manufacturing (three-dimensional (3D) printing), subtractive machining, photo lithography with chemical etching, laser ablation and cutting, along with diffusion bonding of layers and flow channels can be employed to create metallurgical bonds between the various layers and structures reducing the contact resistance between the layers to reduce the overall electrical resistance of the porous assemblies. Lower overall electrical resistance of the porous assemblies can improve performance when producing hydrogen. The metallurgical bonds between the various layers can also help to improve the corrosion resistance of the porous assemblies allowing them to last for years in use before degradation thereof.

[0163] In contrast to assembly of multiple separate / individual flow field layers (e.g., titanium screens), the flow fields disclosed herein can be manufactured at lower cost, and with greater flexibility for production of small (e.g., 4” x 4” (101.6 mm x 101.6 mm)) or large (e.g., 11” x 21” (279.4 mm x 533.4 mm) or 24” x 36” (609.6 mm x 914.4 mm)) parts, as the flow field can be produced by continuous processing, for example, using a roll mill.

[0164] The flow field (e.g., fabricated at least in part by additive manufacturing) of the present disclosure can be assembled with and / or joined to other flow fields of the present disclosure (e.g., fabricated at least in part by the same additive manufacturing process, or other (additive manufacturing) processes / methods). For example, an electron-beam additive manufactured flow field can be assembled with one or more laser-sintered monolith support structures or substrates.

[0165] The present disclosure can provide for a 3D printed flow field that can replace fabrication of assembly of multiple separate flow fields (e.g., screens), and thus eliminate multiple fabrication steps (cost effective), and can improve performance through optimization of the pore microstructure and tortuosity for fluid flow of the flow field.

[0166] A 3D printed flow field can have a wide range of pore sizes (e.g., from 0.1 micrometers (µm) to greater than 1 mm), and a wide range of porosities (e.g., from 5 to 95%). The flow field can have a range of dimensions (e.g., from 0.1” (inches) (2.54 mm) to the maximum size allowed by additive manufacturing machines (e.g., 14” x 14” (355.6 mm x 355.6 mm)); and that the flow field can be of any suitable shape (e.g., square, rectangle, circle, etc.).

[0167] The additive manufacturing or 3D printing processes as described herein can be used to manufacture flow fields with basic or complex shapes / designs (e.g., and that are highly effective yet small in shape). The shapes / designs of the flow fields of the present disclosure that can be manufactured using additive manufacturing or a 3D printing processes can yield complex fluid flow patterns. With 3D printed flow field, the design freedom expands. For example, 3D printed pore structure tortuosity of the flow field can be designed to optimize performance (fluid flow). Adjacent components (e.g., adjacent non-porous components) can be 3D printed with the flow field.

[0168] With reference to, for example, FIG. 1, FIG. 7, FIG. 8, FIG. 9A, FIG. 9B, and FIG. 14, through-holes, grooves, or flow channels can be produced using an additive manufacturing (3D printed) method such as laser powder bed fusion or can be formed using a wide variety of machining methods including precision milling, laser cutting, photolithography etching, or other comparable micro machining methods. With further reference to, for example, FIG. 7, channels can be machined in the porous layer using a wide variety of micro machining including precision milling, laser ablation, or photolithography / etching. Porous metallic layer 1 or layer 3 can be made by a modified roll compaction and sintering technique in which one of the compactions rolls is smooth and the other compaction roll is grooved.

[0169] With reference to, for example, FIG. 2A, FIG. 2B, FIG. 2C, FIG. 3A, FIG. 3B, FIG. 3C, FIG. 4A, FIG. 4B, FIG. 4C, FIG. 5A, FIG. 5B, FIG. 5C, FIG. 10A, FIG. 10B, FIG. 10C, FIG. 11A, FIG. 11B, FIG. 11C, FIG. 12A, FIG. 12B, FIG. 12C, FIG. 13A, FIG. 13B, and FIG. 13C, the titanium structures defining the flow channels or the capillary structures fabricated using additive manufacturing. Methods of manufacturing can include cutting grooves into porous titanium layers and bonding the layers together to make the (internal capillary) flow channels with or without the solid titanium support layer.

[0170] With reference to, for example, FIG. 6, each of porous metallic layer 1, support layer 2, and layer 3 can be fabricated utilizing standard roll compaction and sintering methods.

[0171] With reference to, for example, FIG. 24A, FIG. 24B, FIG. 24C, FIG. 25A, FIG. 25B, FIG. 25C, FIG. 26A, FIG. 26B, FIG. 26C, FIG. 27A, FIG. 27B, and FIG. 27C, protrusions were fabricated using additive manufacturing. The protrusions can be fabricated using laser ablation, chemical etching via photo lithography, or other suitable process from solid or porous titanium layer.

[0172] The porous assembly disclosed herein are especially useful and can be configured for use as an anode pack in an electrolyzer.

[0173] The following examples are provided to illustrate the present disclosure. The examples are merely illustrative and are not intended to limit devices made in accordance with the disclosure to the materials, conditions, or process parameters set forth therein. EXAMPLES

[0174] Electrical resistance measurements were made using a 1" (2.54 centimeter) square gold plate over copper contact platens, with 400 pounds per square inch per square inch (psi / in2) (0.43 megapascals per square centimeter (MPa / cm2)) contact pressure, and 4-wire direct current (DC) measurement at 6.45 amperes (A) supply current. Results are provided in Table 1.Table 1 Current Voltage Resistance (millivolts (milliOhms) )The data showed that the pleated (FIGS. 18-19) and dimpled (FIGS. 21-23) structures had the highest resistance and all of the other examples showed similar resistance values and were all desirable much lower.

[0175] Water flow testing of 4 x 4" (101.6 x 101.6 millimeter (mm)) porous assemblies was performed. The flow fields of Comparative Examples 1A-1E and 2 included layers of expanded screens. “Area” refers to flow channel height * flow channel width (101.6 mm). Water flow was at a pressure of 1 pound per square inch (psi) (0.007 megapascals (MPa)) and in a direction parallel to the extending channels (with the exception of FIGS. 26-27, in which the channel extend 45° relative to the flow direction). Permeability Coefficient was calculated as (Flux * Viscosity * Thickness) / dP (differential pressure) and provides a characteristic of media flow. Results are provided in Table 2. Table 2 Flow Field Flow Area Water Flow Flux Permeability Relative to Description Channel (square (liters per (LPM / m2) Coefficient ComparativeThe data showed that the structures of FIGS 2-3, 4-5, 10-11, 12-13, 24-25, and 26-27 all had desirably high flow, flux, and Permeability Coefficients compared to the Comparative Examples.

[0176] Resistance of anode packs were measured utilizing industry standard 4-wire direct current (DC) resistance measurement methods. One inch (25.4 mm) square by 0.5 inch (12.7 mm) thick copper blocks plated with 24 karat gold were fabricated for the measurements. One ofthe gold-plated blocks is placed onto a benchtop press with an electrical insulator placed between the block and the base of the press. A 1-inch (25.4 mm) square sample is cut from the anode pack for testing and is placed on top of the lower block. A second block is then placed on top of the anode pack with a second insulator to electrically isolate the test apparatus from the press and the desired compaction force is applied to compress the layers together. A programmable DC power supply was used to apply a current load of 6.45 amperes / in2(1 ampere / cm2) from the lower block to the upper block. A separate voltage meter capable of measurements down to micro-volt levels was also attached to the upper and lower gold-plated blocks using separate lead wires to measure the voltage drop across the sample under the applied current load. The electrical resistance was calculated by dividing the measured voltage drop by the applied current to calculate the resistance following Ohms law (V=IR). Prior to measuring, the gold blocks are clamped together with no sample therebetween under the same contact forces to be used for the measurements with the applied current and the voltage reading was zeroed out to eliminate the resistance of the overall system. For the measurements presented here, contact forces of 200, 300, 400, 600, 800, and 1,000 pounds were applied with the electrical readings taken at each of the applied forces. Because the gold-plated contact blocks and test samples are 1” x 1”, the pressure loading (pounds / inch2) has the same numerical value as the applied compression force as the contact area is 1 inch2. Results are shown in FIGS. 29 and 30.

[0177] FIG. 29 shows results for two samples, each with flow fields including layers of expanded screens (also referred to herein as “mesh”). One sample was bonded, while the other sample was unbonded. The results demonstrate that bonding results in a resistance reduction, for example, a resistance reduction of about ten times at lower pressure. FIG. 30 demonstrates that flow fields as disclosed herein resulted in at least as good, if not better, e.g., lower, resistance as compared to a bonded, mesh flow field.

[0178] Pressure drop measurements (in pounds per square inch (psi)) of assemblies were made at various water flow rates. Anode packs were 4-inch (101.6 mm) square. A test fixture was fabricated from stainless steel plate with a 4 inch (101.6 mm) square cavity with a depth of 1 mm greater than the thickness of the anode pack. The extra 1 mm depth was to accommodate flat rubber gaskets placed on either side for the anode packs to make a watertight seal. The fixture also had a lead in manifold with a 1 / 8 inch NPT (National Pipe Thread) ports on opposite ends of the cavity to allow water flow into one edge of the square and to exit the opposite edge of theanode pack providing a uniform distribution of water at the inlet and outlet ends. After the sample to be tested with the rubber gaskets are placed into the cavity, a second stainless steel plate was placed on top and the first plate and the plates clamped together to make watertight seals and to provide a water flow path from one edge of the anode pack to the opposite edge. A water flow controller was connected to the inlet of the fixture and pressure sensors attached to the inlet and outlet ports to measure the pressure drop across the device during water flow. The pressure drop is calculated by subtracting the outlet pressure from the inlet pressure. Water flow rates from 50 to about 150 milliliters / minute (mL / min) were set and the pressure drop measured for each flow rate. FIG. 31 demonstrates that flow fields as disclosed herein resulted in improved, e.g., lower, pressure drop as compared to bonded, mesh flow fields.

[0179] Disclosed herein is a porous assembly for use as an anode pack in an electrolyzer comprising a flow field configured to provide moisture to a proton exchange membrane of an electrolyzer, conduct heat away from the proton exchange membrane, and extract oxygen from the proton exchange membrane through the flow of water, the flow field having a thickness of 0.003 to 0.1” (0.08 to 2.54 mm), or 0.003 to 0.05” (0.08 to 1.27 mm); and a porous metallic layer having a thickness of 0.003 to 0.05” (0.08 to 1.27 mm) and a mean pore size of 0.2 to 20 µm on the flow field.

[0180] The porous assembly can further comprise a support layer comprising a porous metal layer, wherein the metal comprises titanium, nickel, or a combination thereof; and / or the flow field can comprise a metal layer comprising through-holes, wherein the metal comprises titanium, nickel, or a combination thereof; and / or the flow field can comprise a media grade 40 or higher metal sheet, wherein the metal comprises titanium, nickel, or a combination thereof; and / or the flow field can comprise a media grade 20 or higher metal sheet, wherein the metal comprises titanium, nickel, or a combination thereof; and / or the flow field can comprise a metal layer comprising channels, wherein the metal comprises titanium, nickel, or a combination thereof; and / or the flow field can comprise a corrugated metal layer, wherein the metal comprises titanium, nickel, or a combination thereof; and / or the flow field can comprise a dimpled metal layer, wherein the metal comprises titanium, nickel, or a combination thereof, and wherein the flow field comprises indentations in opposing sides of the dimpled metal layer; and / or the porous metallic layer can comprise grooves in a surface of the porous metallic layer facing the porous metallic layer; and / or the flow field can comprise more than one layer.

[0181] Disclosed herein is a fixture comprising the porous assembly disclosed herein; and a non-porous metal layer, wherein the metal comprises titanium, nickel, or a combination thereof. Disclosed herein is a method for fabricating the porous assembly disclosed herein, the method comprising fabricating the flow field; and positioning a porous metallic layer on the flow field. The flow field can be fabricated at least in part by additive manufacturing; and / or the flow field can be fabricated at least in part by a 3D printing process; and / or the method can further comprise fabricating the porous metallic layer by additive manufacturing; and / or the flow field can be fabricated at least in part by laser milling, chemically milling via photo lithography techniques, or a combination thereof.

[0182] While particular embodiments have been described, alternatives, modifications, variations, improvements, and substantial equivalents that are or may be presently unforeseen may arise to applicants or others skilled in the art. Accordingly, the appended claims as filed and as they may be amended are intended to embrace all such alternatives, modifications variations, improvements, and substantial equivalents.

[0183] The ranges disclosed herein are inclusive of the endpoints, and the endpoints are independently combinable with each other (e.g., ranges of “up to 25 wt.%, or, more specifically, 5 wt.% to 20 wt.%”, is inclusive of the endpoints and all intermediate values of the ranges of “5 wt.% to 25 wt.%,” etc.). “Combinations” is inclusive of blends, mixtures, alloys, reaction products, and the like. The terms “first,” “second,” and the like, do not denote any order, quantity, or importance, but rather are used to distinguish one element from another. The terms “a” and “an” and “the” do not denote a limitation of quantity and are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. Thus, reference to “an” element in a claim followed by reference to “the” element is inclusive of one element and a plurality of the elements. “Or” means “and / or” unless clearly stated otherwise. Reference throughout the specification to “some embodiments”, “an embodiment”, and so forth, means that a particular element described in connection with the embodiment is included in at least one embodiment described herein, and may or may not be present in other embodiments. In addition, it is to be understood that the described elements may be combined in any suitable manner in the various embodiments. A “combination thereof’ is open and includes any combination comprising at least one of the listed components or properties optionally together with a like or equivalent component or property not listed.

[0184] It will be understood that when an element is referred to as being “on” another element, it can be directly on the other element or intervening elements may be present therebetween. In contrast, when an element is referred to as being “directly on” another element, there are no intervening elements present.

[0185] Unless defined otherwise, technical and scientific terms used herein have the same meaning as is commonly understood by one of skill in the art to which this application belongs. All cited patents, patent applications, and other references are incorporated herein by reference in their entirety. However, if a term in the present application contradicts or conflicts with a term in the incorporated reference, the term from the present application takes precedence over the conflicting term from the incorporated reference.

[0186] Although the systems and methods of the present disclosure have been described with reference to exemplary embodiments thereof, the present disclosure is not limited to such exemplary embodiments and / or implementations. Rather, the systems and methods of the present disclosure are susceptible to many implementations and applications, as will be readily apparent to persons skilled in the art from the disclosure hereof. The present disclosure expressly encompasses such modifications, enhancements and / or variations of the disclosed embodiments. Since many changes could be made in the above construction and many widely different embodiments of this disclosure could be made without departing from the scope thereof, it is intended that all matter contained in the drawings and specification shall be interpreted as illustrative and not in a limiting sense. Additional modifications, changes, and substitutions are intended in the foregoing disclosure. Accordingly, it is appropriate that the appended claims be construed broadly and in a manner consistent with the scope of the disclosure.

Claims

CLAIMS What is claimed is:

1. A porous assembly for use as an anode pack in an electrolyzer comprising: a flow field configured to provide moisture to a proton exchange membrane of an electrolyzer, conduct heat away from the proton exchange membrane, and extract oxygen from the proton exchange membrane through the flow of water, the flow field having a thickness of 0.003 to 0.1” (0.08 to 2.54 mm), or 0.003 to 0.05” (0.08 to 1.27 mm); and a porous metallic layer having a thickness of 0.003 to 0.05” (0.08 to 1.27 mm) and a mean pore size of 0.2 to 20 µm on the flow field.

2. The porous assembly of claim 1, further comprising a support layer comprising a porous metal layer, wherein the metal comprises titanium, nickel, or a combination thereof.

3. The porous assembly of claim 1, wherein the flow field comprises a metal layer comprising through-holes, wherein the metal comprises titanium, nickel, or a combination thereof.

4. The porous assembly of claim 1, wherein the flow field comprises a media grade 40 or higher metal sheet, wherein the metal comprises titanium, nickel, or a combination thereof.

5. The porous assembly of claim 1, wherein the flow field comprises a media grade 20 or higher metal sheet, wherein the metal comprises titanium, nickel, or a combination thereof.

6. The porous assembly of claim 1, wherein the flow field comprises a metal layer comprising channels, wherein the metal comprises titanium, nickel, or a combination thereof.

7. The porous assembly of claim 1, wherein the flow field comprises a corrugated metal layer, wherein the metal comprises titanium, nickel, or a combination thereof.

8. The porous assembly of claim 1, wherein the flow field comprises a dimpled metal layer, wherein the metal comprises titanium, nickel, or a combination thereof, and wherein the flow field comprises indentations in opposing sides of the dimpled metal layer.

9. The porous assembly of claim 1, wherein the porous metallic layer comprises grooves in a surface of the porous metallic layer facing the porous metallic layer.

10. The porous assembly of claim 1, wherein the flow field comprises more than one layer.

11. A fixture comprising: the porous assembly of claim 1; and a non-porous metal layer, wherein the metal comprises titanium, nickel, or a combination thereof.

12. A method for fabricating the porous assembly of claim 1, the method comprising: fabricating the flow field; and positioning a porous metallic layer on the flow field.

13. The method of claim 12, wherein the flow field is fabricated at least in part by additive manufacturing.

14. The method of claim 12, wherein the flow field is fabricated at least in part by a 3D printing process.

15. The method of claim 12, further comprising fabricating the porous metallic layer by additive manufacturing.

16. The method of claim 12, wherein the flow field is fabricated at least in part by laser milling, chemically milling via photo lithography techniques, or a combination thereof.

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