Metal-supported electrochemical cell with robust structure

Abstract

The present invention relates to reinforced porous metal substrates useful in robust metal supported electrochemical cells and methods for making the same. One embodiment of the invention relates to repeating units of robust metal supported electrochemical cells formed by welding or diffusion bonding a reinforced porous metal substrate to a metal frame. Another embodiment of the invention relates to electrochemical cells and stacks.

Description

[Technical Field]

[0001] Rights enjoyed by the government This invention was made with U.S. Government support under the auspices of the Department of Defense under Contract No. W911NF19P0036. The U.S. Government has rights to certain patents related to this invention.

[0002] Identification of related applications This application claims the benefit of U.S. Provisional Patent Application No. 63 / 160,200, filed March 12, 2021, the contents of which are incorporated herein by reference.

[0003] One embodiment of the present invention relates to a porous reinforced metal substrate useful in metal-supported electrochemical cells, such as metal-supported solid oxide fuel cells (MS-SOFCs) or metal-supported solid oxide electrolysis cells (MS-SOECs). The present invention also relates to a method for fabricating the porous reinforced metal substrate. Yet another embodiment of the present invention relates to a robust electrochemical cell. One embodiment of the present invention relates to an electrochemical cell stack fabricated as a repeating unit of multiple electrochemical cells. [Background technology]

[0004] An electrochemical cell consists of three essential layers: an oxygen electrode, an electrolyte, and a fuel electrode, arranged in a stacked (sandwich) structure. Specifically, a solid oxide fuel cell (SOFC) includes an oxygen electrode, which reduces oxygen molecules from an electron source to oxide ions. The electrolyte, which constitutes the intermediate layer, functions as a medium for transporting the oxide ions from the oxygen electrode to the fuel electrode. The fuel electrode oxidizes fuel, such as hydrogen, carbon monoxide, or a mixture thereof, with the oxide ions to produce water and carbon dioxide, respectively, while simultaneously producing electrons. The electrons generated by multiple fuel electrodes connected to an external electrical circuit are transferred to the oxygen electrode through the external electrical circuit, generating useful electricity. Because a single electrochemical cell typically provides only low-voltage power, a higher-voltage, higher-power electrochemical cell stack is formed by connecting multiple individual electrochemical cells, each incorporating connection terminals, gas flow paths, and other components as needed, in series or parallel. Herein, each additional cell required to form the electrochemical cell stack is referred to as a "repeating unit of the electrochemical cell."

[0005] A technique for using a porous metal substrate to support cell components, including the fuel electrode, electrolyte, and oxygen electrode, is disclosed, providing structural integrity and physical strength to the electrochemical cell. Herein, electrochemical cells in which cell components are adjacent to a porous metal substrate, such as metal-supported solid oxide fuel cells (MS-SOFCs), are referred to as "metal-supported." Conventional methods for bonding repeating electrochemical cell units to form a stack result in structural problems due to sealing issues, uneven compression, and mismatched coefficients of thermal expansion (CTE) between materials. Welded or diffusion-bonded structures offer numerous advantages in stack assembly, including eliminating gasketing and glass sealing processes, achieving a lighter stack with higher power output, and improving sealing and thermal cycling durability throughout the entire operating process. Unfortunately, welded or diffusion-bonded structures cannot be applied to porous metal substrates. Highly porous metal substrates have the disadvantage of prone to collapse or deformation of the substrate layer during the welding process.

[0006] In view of the above deficiencies, it is desirable to design a metal-supported electrochemical cell suitable for welded sealing or diffusion bonding construction, and to assemble multiple repeating units of electrochemical cells to form a stack that provides improved strength, durability, and robustness from all operating conditions. Summary of the Invention [Problem to be solved by the invention]

[0007] The present inventors have developed a novel metal-supported electrochemical cell incorporating a porous metal substrate that welds or diffusion bonds the stack assembly. The novel metal-supported electrochemical cell includes an additional layer of metal strip (referred to as a "metal reinforcement") located around the periphery of the porous metal substrate. The metal reinforcement functions as a diffusion-bonded layer that densifies the outer edge, advantageously providing good weldability for cell assembly. By applying weld sealing or diffusion bonding techniques, a robust electrochemical cell can be fabricated, enabling lightweight electrochemical cell stack assemblies with high specific power (kW / kg). The sealing structure also improves durability throughout the entire operating process and thermal cycling capability. Furthermore, the metal substrate that densifies the outer edge (edge) of the metal-supported electrochemical cell of the present invention and the resulting robust electrochemical cell, fabricated using the welding or diffusion sealing methods described below, exhibit improved vibration resistance and durability through startup and transient thermal cycling. [Means for solving the problem]

[0008] Accordingly, one embodiment of the present invention provides a novel porous reinforced metal substrate for use in an electrochemical cell comprising: (a) a porous metal substrate having a first surface; (a) a metal substrate forming a first side and a second side configured as layers having a porosity of about 20% to 50% by volume; (b) a high-density metal reinforcement disposed along at least a portion of the periphery of one side of the porous metal substrate; The dense metal reinforcement functions to provide strength to the porous metal substrate while providing a seat for welding or diffusion bonding. The metal substrate, in addition to the metal reinforcement, provides useful resistance to dents, damage, and deformation during manufacturing and during the welding or bonding process of the laminate. The novel reinforced porous metal substrate of the present invention is useful for fabricating repeating units of metal-supported electrochemical cells, each repeating unit being fabricated by welding or diffusion bonding components to the metal reinforcement.

[0009] One embodiment of the present invention relates to a metal-supported electrochemical cell having a robust structure and including the following stacked configurations (a) to (e):

[0010] (a) oxygen electrode,

[0011] (b) electrolytes;

[0012] (c) fuel electrode;

[0013] (d) a porous metal substrate forming a first side and a second side configured as a layer having a porosity of about 20% to 50% by volume, the first side being positioned adjacent to the fuel electrode; and

[0014] (e) a high density metal reinforcement disposed along at least a portion of the periphery of the second side of the porous metal substrate;

[0015] In one exemplary embodiment of the present invention, the metal-supported electrochemical cell further comprises an intermediate layer disposed between (a) the oxygen electrode and (b) the electrolyte.

[0016] In another exemplary embodiment of the present invention, the metal-supported electrochemical cell further comprises a barrier layer disposed between (c) the fuel electrode and (d) the porous metal substrate.

[0017] In yet another exemplary embodiment of the present invention, the metal-supported electrochemical cell comprises an additional layer of (f) a metal frame attached to (e) a high-density metal reinforcement, the metal frame forming one or more gas flow paths.

[0018] The present invention provides a repeating unit of a metal-supported electrochemical cell, which further comprises, in addition to the above layers (a) to (f), an additional layer of (g) a connection terminal coupled to the metal frame. In another embodiment of the present invention, the connection terminal forms a plurality of gaseous fuel passages disposed on a first side (upper side) of the connection terminal coupled to the metal frame. In yet another embodiment of the present invention, the connection terminal comprises a plurality of oxygen (or air) passages disposed on a second side (lower side) of the connection terminal attached to the metal frame, opposite the first side (upper side). The metal frame, the connection terminal, and the metal-supported electrochemical cells forming the plurality of passages are suitable for assembly into a stack, and each metal-supported electrochemical cell is defined herein as a "repeating unit of a metal-supported electrochemical cell."

[0019] In another embodiment of the present invention, the repeating unit of the metal-supported electrochemical cell may comprise an additional laminate component, such as a non-conductive gasket, a metal mesh current collector, or a combination thereof, which is disposed on a second side (bottom) of the metal-supported electrochemical cell, and a connection terminal opposite the first side is fixed (bonded) to the metal frame.

[0020] Another embodiment of the present invention provides a robust electrochemical cell stack, such as a robust metal-supported solid oxide fuel cell (MS-SOFC) stack, comprising a plurality of repeating metal-supported electrochemical cell units, each repeating unit comprising a metal-supported electrochemical cell (a stack of an oxygen electrode, an electrolyte, a fuel electrode, a porous metal substrate, and a stiffener), a metal frame, and a connection terminal with a gas flow path. Thus, the electrochemical cell stack is fabricated by assembling the plurality of repeating metal-supported electrochemical cell units with a densified metal stiffener.

[0021] A first method for producing a porous reinforced metal substrate according to another embodiment of the present invention includes the following steps (a) and (b).

[0022] (a) screen printing a metal-reinforcing ink along at least a portion of the periphery of one side of a layer of a porous metal substrate having a porosity of about 20% to 50% by volume to form a substrate-ink composite; and

[0023] (b) sintering the substrate-ink composite under conditions sufficient to provide a densified metal reinforcement configured as a layer forming a first side and a second side, the densified metal reinforcement having a porosity of between 20% and 50% by volume and disposed along at least a portion of the periphery of one side of the substrate-ink composite.

[0024] A second method for producing a porous reinforced metal substrate according to another embodiment of the present invention includes the following steps (a) to (c).

[0025] (a) providing a green metal sheet comprising metal substrate particles and a pore former producing a porosity of about 20% to 50% by volume, and a green metal reinforcement comprising metal particles of the reinforcement;

[0026] (b) applying heat and pressure to at least a portion of the periphery of one side of the raw metal sheet to form a laminated structure; and

[0027] (c) sintering the laminate structure to provide a porous reinforced metal substrate comprising a porous metal substrate configured as a layer forming a first side and a second side, the porous metal substrate having a porosity of 20% to 50% by volume and having a densified metal reinforcement disposed along at least a portion of the periphery of one side of the laminate structure.

[0028] A novel method for assembling the repeating units and stacks of the electrochemical cell of the present invention utilizes a reinforced metal substrate with a high density of pores at the periphery (edge). The present invention is advantageous in that the porous metal substrate is adhered, bonded, or fastened to a metal reinforcement material that serves as a welding and diffusion bonding site, eliminating the need for porcelain (ceramic) and glass sealing processes. This fastening method advantageously reduces the number of components required to assemble the cells into a stack, thereby reducing the overall weight of the stack and increasing the cell power density (kW / kg). The metal-supported cells can be welded or diffusion bonded together with other stack components to improve stack durability and prevent heat leakage and quality degradation due to thermal cycling. [Brief explanation of the drawings]

[0029] [Figure 1] FIG. 1 is a cross-sectional view showing the cell components of a single electrochemical cell supported on a porous reinforced metal substrate according to one embodiment of the present invention.

[0030] [Figure 2] 2 is a bottom view of the porous reinforced metal substrate electrochemical cell of FIG. 1 according to one embodiment of the present invention;

[0031] [Figure 3] FIG. 1 is a cross-sectional view of a single electrochemical cell supported on a porous reinforced metal substrate according to another embodiment of the present invention.

[0032] [Figure 4] FIG. 1 is a cross-sectional view of a single electrochemical cell supported on a porous reinforced metal substrate according to another embodiment of the present invention.

[0033] [Figure 5] 1 is an exploded perspective view showing a stacking process of a metal-supported solid oxide fuel cell with reinforced periphery according to one embodiment of the present invention; FIG.

[0034] [Figure 6] FIG. 1 is an exploded perspective view showing a repeating unit of a perimeter-reinforced metal-supported solid oxide fuel cell according to one embodiment of the present invention on the fuel-multiple passage side of a connecting terminal.

[0035] [Figure 7] FIG. 1 is an exploded perspective view of a repeating unit of a perimeter-reinforced metal-supported solid oxide fuel cell according to one embodiment of the present invention, viewed from the multi-air passage side of the connecting terminal. DETAILED DESCRIPTION OF THE INVENTION

[0036] As used herein, the term "layer" refers to a quasi-two-dimensional (thin-film-like) structure in which the length and width are significantly greater than the thickness. A layer is considered to be a flat surface or thin plate that forms two major parallel surfaces, a "first side" (e.g., top side) and a "second side" (e.g., bottom side). A layer of a first material, monolayer thick, typically covers all or part of the surface or thickness of a second material. The term "layer" as used herein does not limit a layer to a particular shape. Layers can be formed into squares, rectangles, hexagons, circles, ellipses, or any other shape dictated by the design. All layers of the electrochemical cells described herein typically have the same shape, and the outer edges and corners of each layer can be aligned and sealed to form a seal. For purposes of the present invention, it is not necessary for the first material layer to cover the entire surface of the second material. For the purposes of the present invention, components of the present invention configured in a stacked or sandwiched structure will be referred to as "layers" for simplicity, regardless of whether they cover the entire surface of adjacent components.

[0037] That is, in this specification, a reinforcing material that needs to cover only at least a portion of the periphery of a porous metal substrate is referred to as a "layer."

[0038] As used herein, the term "perimeter" usually has the mathematical meaning of a unit of length representing the continuous perimeter measuring the boundary of an object, but the term "perimeter" here most often refers to the boundary of a layer of a porous metal substrate.

[0039] As used herein, the term "periphery" refers to the boundary between an object, area, or surface and its exterior, the location or portion furthest from the center, and thus the periphery of an object also extends downward along the periphery of the object. For purposes of the present invention, the terms "periphery" and "periphery" are used interchangeably. In practice, the "periphery" or "periphery" of a layer, such as a porous metal substrate layer, typically has a measurable band width of about 1 mm to about 5 mm, although widths greater than 5 mm are also considered the periphery or periphery of large cells (e.g., cells 10 cm x 10 cm or larger). The range of the periphery band width corresponds approximately to about 1% to 20% of the total length or width of the layer.

[0040] As used herein, the term "porosity" refers to the amount of voids or gaps within a layer of solid material. Porosity is measured as the ratio or percentage of void volume to the total volume occupied by the solid material.

[0041] As used herein, the terms "welding" or "welded" or "welded seal" refer to a manufacturing process for joining metal materials or the like in which multiple components are melted simultaneously at high heat and then cooled to fuse the multiple components together.

[0042] As used herein, the term "diffusion bonding" refers to a welding technique for joining similar and dissimilar metals. Diffusion bonding operates on the principle of solid-state diffusion, whereby atoms at the surfaces of two solid metals disperse into each other over time into the other metal. Diffusion bonding is typically performed in a high-temperature atmosphere, approximately 50% to 75% of the absolute melting temperature of the materials, combined with a pressure process.

[0043] The high density metal reinforcement of the exemplary electrochemical cells herein refers to the structural or foundational element that provides strength, weldability, and durability to the repeating units of the electrochemical cell. A plurality of repeating units fabricated from the high density metal reinforcement of an electrochemical cell stack is referred to herein as a "solid structural" cell stack.

[0044] In this specification, the term "about" is added before the lower limit of a numerical range. Unless otherwise specified, the term "about" modifies both the lower and upper limits of the numerical range and contemplates both permissible variations between the lower and upper limits.

[0045] In one exemplary embodiment of the present invention, there is provided a novel porous reinforced metal substrate for use in an electrochemical cell comprising: (a) a porous metal substrate; (a) a porous metal substrate configured as a single layer forming a first side and a second side and having a porosity of about 20% to 50% by volume; and (b) a high density metal reinforcement disposed along at least a portion of the periphery of one side of the porous metal substrate and having a porosity of less than 20% by volume;

[0046] Another exemplary embodiment of the present invention provides a robust metal-supported electrochemical cell having the following stacked components (a) to (c):

[0047] (a) oxygen electrode,

[0048] (b) electrolytes;

[0049] (d) a porous metal substrate forming a first side and a second side and configured as a single layer having a porosity of about 20% to 50% by volume, the first side being positioned adjacent the fuel electrode;

[0050] (c) a fuel electrode; and

[0051] (e) a high density metal reinforcement disposed along at least a portion of the periphery of the second side of the porous metal substrate and having a porosity of less than 20% by volume.

[0052] In yet another exemplary embodiment of the present invention, the pore size of the porous metal substrate is between about 3 μm and 75 μm.

[0053] In yet another exemplary embodiment of the present invention, the porous metal substrate has a thickness of about 80 μm to 1000 μm.

[0054] In yet another exemplary embodiment of the present invention, the high density reinforcement has a thickness of about 50 μm to 1000 μm.

[0055] The present invention and its embodiments will be more clearly appreciated and understood with reference to the accompanying drawings. FIG. 1 illustrates a cross-sectional view of one embodiment of the present invention in which a single electrochemical cell 10 is supported on a porous metal substrate 4, the porous metal substrate 4 being secured to a metal reinforcement 6 by welding or diffusion bonding techniques. The electrochemical cell 10 illustrated in FIG. 1 comprises stacked (sandwich) cell components including an oxygen electrode 1 (also referred to as the "cathode"), an electrolyte 2, and a fuel electrode 3 (also referred to as the "anode"). The fuel electrode 3 is secured and supported on a porous metal substrate 14 comprising the porous metal substrate 4, and a densified (densified) metal reinforcement 6 is attached to the outer periphery (outer edge) of the bottom surface 8 of the porous metal substrate layer 4. The fuel electrode 3 is disposed on the top surface 7 of the porous metal substrate layer 4. FIG. 2, which illustrates a view of the porous metal substrate 4 from the bottom of the electrochemical cell 10, shows the metal reinforcement 6 disposed on the outer periphery 5 of the electrochemical cell 10.

[0056] 3, a cross-sectional view of another embodiment of the present invention, electrochemical cell 20, comprises laminated cell components: oxygen electrode 1, electrolyte 2, and fuel electrode 3. Again, fuel electrode 3 is provided on and supported by a porous metal substrate 14 comprising a porous metal substrate layer 4 and having a reinforced (densified) outer periphery, with a metal reinforcement 6 attached to the periphery of the bottom surface 8 of porous metal substrate layer 4. In this embodiment, metal reinforcement 6 is attached along the outer periphery of porous metal substrate 4.

[0057] Another embodiment of the electrochemical cell 30 of the present invention, shown in cross section in Figure 4, includes laminated cell components similar to those of Figure 3: oxygen electrode 1, electrolyte 2, and fuel electrode 3. Again, fuel electrode 3 is provided and supported on a porous metal substrate 14 that includes a porous metal substrate layer 4 and is reinforced (densified) at its outer periphery, with a metal reinforcement 6 attached to the periphery of the bottom surface 8 of the porous metal substrate layer 4. In this embodiment, the metal reinforcement 6 is attached along the outer periphery of the porous metal substrate 4 and the fuel electrode 3. In yet another embodiment of the present invention (not shown), the metal reinforcement 6 is attached along the outer periphery of the porous metal substrate 4, the fuel electrode 3, and the electrolyte 2.

[0058] Metal substrates typically comprise any metallic material, such as a pure single metallic element or a combination of metallic elements, such as an alloy. Non-limiting examples of suitable metallic substrates include ferritic and austenitic alloys containing primarily iron, about 10% to about 40% by weight of chromium, and minor amounts of any metallic element selected from the group consisting of yttrium, manganese, nickel, niobium, aluminum, lanthanum, molybdenum, and mixtures thereof. Metal substrates containing 0% to 30% by weight of yttrium are suitable. The alloy of the metal substrate may also contain minor amounts of carbon, such as about 0.03% to about 0.16% by weight. In one embodiment of the porous metal substrate of the present invention, the substrate comprises a ferritic alloy. In another embodiment of the porous metal substrate of the present invention, the substrate comprises a ferritic iron-chromium alloy. Other suitable porous metal substrates include iron-nickel-chromium alloys, iron-cobalt alloys, iron-aluminum-chromium alloys, and chromium alloys.

[0059] A "porous" metal substrate is required, in which multiple pores, grooves, and / or voids are formed throughout and within the metal substrate to promote the diffusion of gas components. Metal substrates typically have pores with diameters or critical dimensions of about 3 μm to 75 μm. The typical porosity of a metal substrate is about 20% to about 50% by volume relative to the total volume of the porous metal substrate. The metal substrate is formed in a single layer with a thickness of about 80 μm (0.08 mm) to about 1000 μm (1 mm), preferably about 100 μm (0.1 mm) to about 500 μm (0.5 mm).

[0060] The high-density metal reinforcement can be formed from any metallic element or alloy that provides the strength, weldability, and durability required for the electrochemical cell under manufacturing and operating conditions. That is, the metal reinforcement can include metallic materials such as single metallic elements or combinations of metallic elements, such as alloys. In one exemplary embodiment of the present invention, the metal reinforcement is a metallic element or alloy of the same composition as the porous metal substrate. In another exemplary embodiment of the present invention, the metal reinforcement is a metallic element or alloy of a different composition from the porous metal substrate. Non-limiting examples of suitable materials for the metal reinforcement include ferritic and austenitic alloys, preferably ferritic alloys, containing primarily iron and about 10% to about 40% chromium by weight, but optionally containing small amounts of other metallic elements selected from the group consisting of yttrium, manganese, nickel, niobium, aluminum, lanthanum, molybdenum, and mixtures thereof. The alloy of the metal reinforcement can also contain a small amount of carbon, about 0.03% to about 0.16% by weight. Other suitable reinforcing materials are iron-nickel-chromium alloys, iron-cobalt alloys, iron-aluminum-chromium alloys and chromium alloys.

[0061] The metal reinforcement is typically formed of a material that is denser ("high density") than the porous metal substrate, with low porosity. In one embodiment of the present invention, the metal reinforcement has a porosity of less than about 20% by volume, based on the total volume of material forming the metal reinforcement. The metal reinforcement typically has a thickness (or height) of about 50 μm (0.05 mm) to about 1,000 μm (1 mm), preferably about 200 μm (0.2 mm) to about 700 μm (0.7 mm).

[0062] The metal reinforcement 6 provided as an integral frame in the electrochemical cell 10 shown in FIGS. 1 and 2 is provided along the entire outer edge or periphery 5 of the porous metal substrate 4. The metal reinforcement 6 is attached to the outer edge of the bottom surface 8 of the porous metal substrate 4, opposite the top surface 7 on which the fuel electrode (anode) 3 is attached. In other embodiments of the present invention, the strength and support of the metal reinforcement 6 can be further improved by providing additional reinforcing struts on the bottom surface 8 of the porous metal substrate 4. For example, cross-shaped or other geometrically shaped struts can be fixed to or across the bottom surface 8 of the porous metal substrate 4 to reinforce the outer metal reinforcement 6. In another exemplary embodiment of the present invention, the metal reinforcement 6 is located on two parallel outer edges rather than the entire periphery of the bottom surface 8 of the porous metal substrate 4. In another exemplary embodiment of the present invention, the metal reinforcement 6 is located at the four corners rather than the entire periphery of the bottom surface 8 of the porous metal substrate 4. The metal reinforcement 6 serves as a base weld during stack assembly.

[0063] The metal reinforcement can be attached to the porous metal substrate using any method known in the art, provided that it does not result in unacceptable deformation or damage to the porous metal substrate. Two processes have been developed to allow for the production of reinforced porous metal substrates: (a) cast strip lamination and (b) metallic ink printing.

[0064] Figure 5 illustrates the casting strip lamination process. In this lamination process, a fabric reinforcement layer 12 is selected from a thin green strip frame and laminated to the bottom periphery of a green porous metal sheet 11, which contains a precursor for the porous metal substrate. Green porous metal sheets 11 are commercially available from green strip manufacturers, who use selected metal powder particles for the metal substrate, a given pore former to impart the desired porosity and pore size to the metal substrate, and the desired reinforcing metal. The heat-pressure lamination process shown in Figure 5 applies pressure (in the direction of the vertical arrows) and heat to laminate the fabric reinforcement layer 12, which serves as the metal reinforcement, to the periphery of the green porous metal sheet 11. Typical heat-pressure conditions are a temperature of about 50°C to about 150°C and a pressure of about 30 lbs / sq in (30 psi, 206.8 kPa) to about 500 psi (3,447 kPa). The laminate structure 9 formed by the lamination process in a reducing atmosphere, such as a mixture of hydrogen and an inert (non-reactive) gas, is co-sintered at a sufficient temperature to form a porous reinforced metal substrate 40 having a metal-reinforced, dense outer periphery. In one embodiment of the present invention, the reducing atmosphere comprises about 1% to about 20% by volume of hydrogen in an inert gas, such as nitrogen or argon. An acceptable sintering process involves heating from ambient temperature to a temperature of about 900°C to 1300°C. One or more additional layers of metal reinforcement can be added as needed to build up the metal reinforcement to a desired thickness. The porous reinforced metal substrate 40 obtained by this lamination process, in one embodiment of the present invention, comprises a 0.27 mm thick metal substrate bonded to a 0.47 mm thick metal reinforcement.

[0065] Multiple layers can be stacked to form thick layers suitable for welding. Additionally, the outer edges of the substrate can be strengthened to improve flatness. Acceptable substrate flatness is necessary to maintain good print quality of the cell components. The present invention has the advantage of forming multiple layers substantially flat, allowing for intimate attachment of electrode layers onto the layers. The term "flat" refers to a flat surface formed by lines or tracks that are substantially free of irregularities. The acceptable flatness of the substrate is determined by visually inspecting the layers for warpage using an optical microscope at approximately 10-20x magnification.

[0066] A second method for producing a porous reinforced metal substrate involves screen printing a metal-reinforced ink onto the periphery of a porous metal substrate, followed by sintering the resulting ink-metal substrate composite. The metal-reinforced ink typically contains a mixture of a solvent, a binder, metal-reinforced composition particles, and one or more optional plasticizers and dispersants. The solvent used in the metal-reinforced ink is selected from common volatile organic solvents. The amount of organic solvent, typically selected from the group consisting of alcohols, esters, and ketones, is typically about 5% to 30% by weight based on the total weight of the metal-reinforced ink. The binder is typically selected from commercially available binder formulations, including, but not limited to, cellulose-based compounds such as ethyl cellulose. The amount of binder is typically about 5% to 30% by weight based on the total weight of the metal-reinforced ink. The average particle size of the metal particles in the metal-reinforced ink is typically about 5 μm to about 25 μm. Suitable plasticizers include phthalate ester and glycol groups, typically added in amounts of about 1% to about 20% by weight based on the total weight of the metal-reinforced ink. Suitable dispersant amounts include fish oil and amine-based dispersants, added at about 1% to about 20% by weight based on the total weight of the metal-reinforced ink. Depending on the desired deposition properties, the solids loading and number of coats of the metal-reinforced ink can be controlled to form a metal-reinforced ink layer of optimal thickness. For example, the ink-metal substrate composite is sintered in a reducing atmosphere containing a mixture of hydrogen and an inert gas, such as nitrogen or argon. In one embodiment of the present invention, the reducing atmosphere is an inert gas containing about 1% to 20% by volume of hydrogen. An acceptable sintering process involves heating from ambient temperature to a temperature of about 900°C to 1300°C.

[0067] FIG. 6 shows a perspective view of a metal-supported solid oxide fuel cell repeating unit (referred to as a "repeat unit") 50 useful in the construction of an electrochemical cell stack. The repeating unit 50 constituting a metal-supported solid oxide fuel cell (abbreviated as "fuel cell") 19 should be understood to include, for example, the multilayer metal-supported electrochemical cell 10 illustrated in FIGS. 1, 3, and 4. The fuel cell 19 can be welded to an additional layer of metal frame 21 (also referred to as a "metal spacer") to form the metal reinforcement 6 of the fuel cell 19. The frame 21 typically includes inlet and outlet gas flow channels. The frame 21 shown in FIG. 6 is secured to an additional layer of metal connection terminal 23. An upper side 29 of the connection terminal 23 (shown in detail, for example, in FIG. 1) facing the metal reinforcement 6 and the fuel electrode 3 is provided with a plurality of gas fuel passages 27 through which a fuel flow, typically hydrogen, carbon monoxide, or a mixture thereof, is supplied to the fuel electrode of the fuel cell 19.

[0068] 7 shows a perspective view of an embodiment of a repeating unit 50 of the present invention, with the repeating unit of FIG. 6 rotated 180 degrees on the horizontal axis to show the bottom surface 33 of the connecting terminal 23. The bottom surface 33 of the connecting terminal 23 is attached to the frame 21 facing the oxygen electrode of the adjacent fuel cell 19. An air flow channel 31 is provided in the connecting terminal 23 to supply air, diluted oxygen, or pure oxygen to the oxygen electrode (1 in FIG. 1) of the fuel cell.

[0069] The repeating structural unit of the metal-supported solid oxide fuel cell, realized by the applicant's novel peripheral metal reinforcement method, has the technical advantage of providing robustness that contributes to vibration resistance, thermal cycling, and rapid start-up. The interior can be hermetically sealed by welding the peripheral, and if a hermetic seal is achieved, gaskets or glass seals are not required. The fuel cell 19 can be fixed to the frame 21 by welding the metal reinforcement 6 (Figure 1).

[0070] The present invention is not limited to the use of a specific fuel electrode, electrolyte, or oxygen electrode. The fuel electrode structure, including the gaseous fuel passages 27, allows for uniform flow of reformed fuel, typically containing hydrogen and carbon monoxide, from the inlet to the outlet. The required electrical and ionic conductivity of the fuel electrode is typically achieved by forming the fuel electrode from a strong, high-temperature cermet material, a composite of porcelain and metal fabricated using standard porcelain processing techniques. Non-limiting examples of cermets useful as the fuel electrode layer include nickel or nickel oxide and a metal oxide composite, where the metal is selected from the group consisting of zirconium, yttrium, cerium, scandium, gadolinium, samarium, calcium, lanthanum, strontium, magnesium, gallium, barium, and mixtures thereof. Non-limiting examples of metals for one embodiment of the present invention include nickel-yttria-stabilized zirconia, gadolinium-doped ceria-mixed nickel, and yttria-doped ceria-zirconia-mixed nickel.

[0071] The solid oxide electrolyte is formed of a dense porcelain layer that conducts oxide ions (O). Examples of materials for forming the solid oxide electrolyte layer include yttria-stabilized zirconia (YSZ), scandia-stabilized zirconia (ScSZ), gadolinium-stabilized ceria (GDC), and ceria-based electrolytes. The newly developed electrolyte reduces resistance issues and improves oxide ion conductivity, forming a robust and high-performance electrolyte layer. Any applicable electrolyte can be used in the present invention.

[0072] The porous electrode, which provides a uniform flow of oxygen across the entire acid electrode, 2 ) must be conducted to the solid oxide electrolyte. A non-limiting example of a material for forming the oxygen electrode is represented by the formula ABO3, where A represents a material selected from the group consisting of barium, strontium, lanthanum, samarium, praseodymium, and combinations thereof, and B represents a material selected from the group consisting of iron, cobalt, nickel, manganese, and mixtures thereof. An exemplary embodiment of the oxygen electrode material of the present invention is any of manganese-modified yttria-stabilized zirconia, lanthanum strontium manganite, lanthanum strontium ferrite, and cobaltite.

[0073] The frame 21 typically has the same material, density, strength, and thickness as the metal reinforcement 6. The frame 21 is welded to the metal reinforcement 6, but it is important that the welding process does not damage the porous metal substrate 40 that supports the fuel electrode 3 in one embodiment of the present invention.

[0074] A metal reinforcement member 6 is attached to the upper side of the frame 21, and a connection terminal 23 is welded to the lower side of the frame 21 on the opposite side. The connection terminal 23 must be made of a conductive material that is resistant to the thermal and chemical environments to which it is exposed, maintaining stable properties that prevent the connection terminal 23 from being deteriorated when exposed to high temperatures on both the oxidation and reduction sides of the fuel cell 19. The connection terminal 23 used in one embodiment of the present invention is made of a metal plate or foil, for example, a high-temperature resistant stainless steel such as an iron-chromium (FeCr) alloy or a nickel-chromium (NiCr) alloy. The present invention is not limited to connection terminals of a specific thickness or material. In one embodiment of the present invention, a gaseous fuel passage 27 is optionally or optionally provided on the side of the connection terminal 23 facing the frame 21, through which a fuel gas flow is supplied to the fuel electrode 3. An oxygen or air flow passage for supplying oxygen or air to the oxygen electrode 1 is provided on the opposite side of the connection terminal 23.

[0075] Non-limiting examples of layers that may be provided as needed or as an option include conventional composition layers. For example, an intermediate layer may be formed of a composition of doped ceria (with an additive selected from Gd, Sm, Y, La, or a mixture thereof). Barrier layers are also typically provided to prevent the diffusion of elements from one layer to another. For example, a barrier layer containing a cermet containing nickel and a metal oxide is provided on the fuel electrode.

[0076] While a finite number of embodiments of the present invention have been described in detail, it should be readily understood that the present invention is not limited to the disclosed embodiments. Rather, the present invention may be modified without description to incorporate any number of variations, alterations, substitutions, or equivalent arrangements commensurate with the spirit and scope of the present invention. It should also be understood that the aspects of the various embodiments of the present invention described may include only some of the described embodiments. Accordingly, the present invention is not to be limited by the foregoing description, but should be limited only by the appended claims.

Claims

1. (a) a porous metal substrate formed in a single layer having a first side and a second side and having a porosity of 20% to 50% by volume; (b) a high density metal reinforcement disposed along at least a portion of a perimeter on one side of the porous metal substrate; 1. A porous, reinforced metal substrate for use in an electrochemical cell, wherein the porous metal substrate and the dense metal reinforcement are sintered materials.

2. The porous metal substrate has pores with diameters of 3 μm to 75 μm.

10. The porous, reinforced metal substrate of claim 1, wherein the dense metal reinforcement has a porosity of less than 20% by volume.

3. The porous metal substrate has a thickness of 80 μm to 1000 μm, 2. The porous reinforced metal substrate of claim 1, wherein the dense metal reinforcement has a material thickness of 50 μm to 1000 μm.

4. 2. The porous reinforced metal substrate of claim 1, wherein the porous metal substrate and the dense reinforcement are each independently formed of a material selected from the group consisting of iron chromium alloys, iron nickel chromium alloys, iron cobalt alloys, iron aluminum chromium alloys, and chromium alloys.

5. The porous, reinforced metal substrate of claim 1 , wherein the dense metal reinforcement further comprises one or more metal posts.

6. 2. The porous reinforced metal substrate of claim 1, wherein the high density metal reinforcement is disposed along the entire perimeter of the porous metal substrate, or along two parallel edges of the porous metal substrate, or at the four corners of the porous metal substrate.

7. (a) screen printing a metal reinforcing ink along at least a portion of a perimeter of one side of a layer of a porous metal substrate having a porosity of 20% to 50% by volume to form a substrate ink composite; (b) sintering the substrate-ink composite to form a metal reinforcement configured as a layer forming a first side and a second side, thereby forming a dense metal reinforcement having a porosity of 20% to 50% by volume and disposed along at least a portion of a perimeter of one side of the substrate-ink composite.

8. The metal reinforcing ink comprises a solvent, a binder, a plasticizer and reinforcing metal particles having a particle size of 5 μm to 25 μm; 8. The method of claim 7, further comprising sintering the substrate-ink composite in a reducing atmosphere containing hydrogen at a temperature between 900°C and 1300°C.

9. (a) forming a green sheet metal including substrate metal particles and a pore former that provides a porosity of 20% to 50% by volume, and forming a green metal reinforcement including metal particles that provide a densified metal reinforcement; (b) applying heat and pressure to a bare metal reinforcement on at least a portion of a periphery of one side of the bare metal sheet to form a laminate; (c) sintering the laminate at a temperature and pressure sufficient to form a reinforced porous metal substrate formed as a layer having a first side and a second side and having a porosity of 20 volume percent to 50 volume percent, and a densified metal reinforcement disposed along at least a portion of a perimeter of one side of the reinforced porous metal substrate.

10. carrying out step (b) by pressing and heating the laminate at a pressure of 206.8 kPa to 3,447 kPa and a temperature of 50° C. to 150° C.; and The method according to claim 9, wherein step (c) is carried out by heating the laminate in a reducing atmosphere at a temperature of 900°C to 1300°C.

11. The following configurations (a) to (d) are laminated together: (a) oxygen electrode, (b) electrolytes; (c) fuel electrode; (d) the porous, reinforced metal substrate of claim 1; The porous reinforced metal substrate has the following features (i) and (ii): (i) a porous metal substrate configured as a layer forming a first side and a second side and having a porosity of 20% to 50% by volume; (ii) a high density metal reinforcement disposed along at least a portion of the periphery of a second side of the porous metal substrate opposite the first side adjacent the fuel electrode; A metal-supported electrochemical cell having a robust structure, characterized in that the porous metal substrate and the dense metal reinforcement are sintered materials.

12. 12. The robust metal supported electrochemical cell of claim 11 further comprising an intermediate layer disposed between (a) the oxygen electrode and (b) the electrolyte, and a barrier layer disposed between (c) the fuel electrode and (d) the porous metal substrate.

13. 12. The robust metal supported electrochemical cell of claim 11 further comprising: (d)(ii) an additional layer comprising a metal frame attached to a dense metal stiffener.

14. Further comprising an additional layer having a connection terminal attached to the metal frame; 14. The robust metal supported electrochemical cell of claim 13, wherein the connection terminal further comprises one or more gaseous fuel passages disposed on a first side adjacent the metal frame and one or more air or oxygen passages disposed on a second side of the connection terminal opposite the first side.

15. A method of manufacturing a ruggedized electrochemical cell comprising: The electrochemical cell stack, wherein each metal supported electrochemical cell is a metal supported solid oxide fuel cell or a metal supported solid oxide electrolysis cell.

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