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 Government support under Contract No. W911NF19P0036 and the support of the United States Government. The United States Government has certain rights in this invention related to patents.

[0002] Disclosure of Related Applications This invention claims the benefit of U.S. Provisional Patent Application No. 63 / 160,200, filed on March 12, 2021, and the contents of the U.S. Provisional Patent Application are incorporated herein by reference.

[0003] One embodiment of the present invention relates to a porous reinforced metal substrate useful for 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 manufacturing a porous reinforced metal substrate. Another embodiment of the present invention relates to a robust-structured electrochemical cell. One embodiment of the present invention relates to an electrochemical cell stack manufactured as a repeating structural unit of a plurality of electrochemical cells.

Background Art

[0004] An electrochemical cell consists of three essential layers: an oxygen electrode, an electrolyte, and a fuel electrode, arranged in a layered (sandwich) structure. Specifically, a solid oxide fuel cell (SOFC) includes an oxygen electrode that reduces oxygen molecules from an electron source to oxide ions, an electrolyte in the intermediate layer that acts as a medium for transferring oxide ions from the oxygen electrode to the fuel electrode, and the fuel electrode's function oxidizes fuels such as hydrogen, carbon monoxide, or mixtures thereof with oxide ions to produce water and carbon dioxide, respectively, while simultaneously generating electrons. Electrons generated from multiple fuel electrodes connected to an external electrical circuit are sent to the oxygen electrode via the external electrical circuit, generating useful electricity. Since a single electrochemical cell typically only provides low-voltage power, multiple individual electrochemical cells incorporating connection terminals, gas flow paths, and other components as needed are connected in series or parallel to form a higher-voltage, higher-power electrochemical cell stack. In this specification, each additional cell required to form an electrochemical cell stack is referred to as an "electrochemical cell repeating unit."

[0005] A technique is disclosed for supporting cell components, including fuel electrodes, electrolytes, and oxygen electrodes, using a porous metal substrate, thereby maintaining the structure and providing physical strength to the electrochemical cell. In this specification, 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 of joining repeating structural units of electrochemical cells to form laminates suffer from sealing problems, non-uniform compression problems, and structural problems due to mismatches in the coefficients of thermal expansion (CTE) between materials. Welding or diffusion bonding structures reduce gasket and glass sealing processes, enabling higher-power, lighter laminates, and improving sealing performance and thermal circulation durability throughout the entire operation, bringing many advantages to the assembly of the laminate. Unfortunately, welding or diffusion bonding structures cannot be applied to porous metal substrates. High-porosity porous metal substrates have the drawback of being prone to substrate layer collapse or deformation during the welding process.

[0006] Considering the above defects, it is desirable to design a metal-supported electrochemical cell suitable for a welded or diffusion-bonded structure, and to assemble repeating units of multiple electrochemical cells to form a laminate that improves strength, durability, and robustness under all operating conditions. [Overview of the Initiative] [Problems that the invention aims to solve]

[0007] The inventors have developed a novel metal-supported electrochemical cell incorporating a porous metal substrate that welds or diffuse-bonds laminated assembly components. The novel metal-supported electrochemical cell comprises an additional layer of metal strip ("metal reinforcement") positioned on the outer periphery of the porous metal substrate. The metal reinforcement, which functions as a diffusion bonding layer that densifies the outer edge, is advantageous in that it provides good weldability for cell assembly. By applying welding or diffusion bonding technology, a robust electrochemical cell is manufactured, enabling the realization of lightweight electrochemical cell-based laminated assembly components and achieving high specific power (kW / kg). Furthermore, the sealing structure improves durability throughout all operating processes and enhances thermal circulation capacity. Moreover, the metal substrate that densifies the outer edge (end) of the metal-supported electrochemical cell of the present invention and the robust electrochemical cell resulting from the densification are manufactured by the welding or diffusion sealing method described below, and exhibit improved vibration resistance and durability through thermal circulation during startup and transients. [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 having the following configurations (a) and (b). (a) Metal substrates forming the first and second sides, which are composed of layers having a porosity of approximately 20% to 50% by volume, (b) A metal reinforcing material having a porosity of less than 20 volume percent, which is fixed to at least a portion of the outer circumference of one side of a porous metal substrate by welding or diffusion bonding. The metal reinforcing material having the aforementioned porosity has the function of providing strength to a porous metal substrate while forming a seat for welding or diffusion bonding. The metal substrate added to the metal reinforcing material has useful resistance to indentation, 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 manufacturing repeating structural units of metal-supported electrochemical cells, each repeating structural unit being manufactured by welding or diffusion bonding of its components to the metal reinforcing material.

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

[0010] (a) Oxygen electrode,

[0011] (b) electrolytes;

[0012] (c) fuel electrode;

[0013] (d) A porous metal substrate having a first side and a second side, each consisting of layers with a porosity of approximately 20% to 50% by volume, wherein the first side is positioned adjacent to the fuel electrode, and

[0014] (e) A high-density metal reinforcement positioned along at least a portion of the outer circumference of the second side of a porous metal substrate.

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

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

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

[0018] The present invention provides a repeating structural unit of a metal-supported electrochemical cell, further comprising, in addition to the above layers (a) to (f), an additional layer of (f) a connecting terminal coupled to a metal frame. In another embodiment of the present invention, the connecting terminal forms a plurality of gaseous fuel passages located on the first side (upper side) of the connecting terminal coupled to the metal frame. In yet another embodiment of the present invention, the connecting terminal comprises a plurality of oxygen (or air) passages located on the second side (lower side) opposite to the first side (upper side) of the connecting terminal attached to the metal frame. The metal-supported electrochemical cell forming the metal frame, connecting terminal and plurality of passages is suitable for assembly of a laminate, and in this specification, each metal-supported electrochemical cell is defined as a “repeating structural unit of a metal-supported electrochemical cell”.

[0019] In another embodiment of the present invention, the repeating structural unit of the metal-supported electrochemical cell may include additional laminated components such as non-conductive gaskets, metal mesh current collectors, or combinations thereof, the additional laminated components being located on the second side (bottom) of the metal-supported electrochemical cell, and the connection terminals on the opposite side of the first side being fixed (connected) to a metal frame.

[0020] In another embodiment of the present invention, a robust electrochemical cell laminate is provided, such as a metal-supported solid oxide fuel cell (MS-SOFC) laminate, comprising a plurality of repeating structural units of metal-supported electrochemical cells, each repeating structural unit comprising a metal-supported electrochemical cell (a laminated structure of oxygen electrode, electrolyte, fuel electrode, porous metal substrate, and reinforcing material), a metal frame, and a connection terminal having a gas flow path. Accordingly, the electrochemical cell laminate is manufactured by assembling a plurality of repeating structural units of metal-supported electrochemical cells using a high-density metal reinforcing material.

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

[0022] (a) A step of screen printing a metal-reinforced ink along at least a portion of the outer circumference of one side of a porous metal substrate having a porosity of approximately 20% to 50% by volume to form a substrate-ink composite, and

[0023] (b) Sinter the substrate-ink composite under conditions sufficient to prepare a high-density metal reinforcement configured as a single layer forming the first side and the second side, and dispose the high-density metal reinforcement along at least a part of the outer periphery of one side of the substrate-ink composite having a porosity of 20% to 50% by volume.

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

[0025] (a) Prepare a base metal thin plate containing metal substrate particles and a base metal reinforcement containing metal particles of a reinforcing material and a pore-forming agent that generates a porosity of about 20% to 50% by volume.

[0026] (b) Heat and press the base metal reinforcement onto at least a part of the outer periphery of one side of the base metal thin plate to form a laminated structure, and

[0027] (c) Sinter the laminated structure to prepare a porous reinforced metal substrate including a porous metal substrate configured as a single layer forming the first side and the second side, having a porosity of 20% to 50% by volume, and dispose the high-density metal reinforcement along at least a part of the outer periphery of one side of the laminated structure.

[0028] Provide a novel manufacturing method for assembling a repeating structural unit of the electrochemical cell of the present invention and a laminate using a porous reinforced metal substrate with a high density at the outer periphery (end). The present invention is advantageous in that the porcelain (ceramic) sealing process and the glass sealing process are omitted, and the porous metal substrate is adhered, joined or fixed to the metal reinforcement serving as the welding site and the diffusion bonding site. By this fixing method, there are advantages that the number of components required for manufacturing the laminate by assembling the cells can be reduced, the weight of the entire laminate can be reduced, and the cell output density (kW / kg) can be increased. Weld or diffusion bond the metal-supported cell with other laminate components to improve the durability of the laminate and prevent heat leakage and quality deterioration associated with thermal cycling.

Brief Description of the Drawings

[0029] [Figure 1] 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] Figure 1 is a bottom view showing the bottom of an electrochemical cell made of a porous reinforced metal substrate according to one embodiment of the present invention.

[0031] [Figure 3] 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] 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] Exploded perspective view showing the stacking process of a metal-supported solid oxide fuel cell with a reinforced outer perimeter according to one embodiment of the present invention.

[0034] [Figure 6] An exploded perspective view showing a repeating component unit of an outer-circumferential reinforced metal-supported solid oxide fuel cell according to one embodiment of the present invention, on the multi-fuel passage side of the connection terminal.

[0035] [Figure 7] An exploded perspective view showing a repeating component unit of an outer-circumferential reinforced metal-supported solid oxide fuel cell according to one embodiment of the present invention, viewed from the multi-air passage side of the connection terminal. [Modes for carrying out the invention]

[0036] As used herein, the term "layer" refers to a pseudo-two-dimensional (thin film) structure in which the length and width are significantly greater than the thickness. A plane or thin plate forming the "first side" (e.g., top) and "second side" (e.g., bottom) of two main parallel surfaces is considered a layer. A first material layer of single thickness typically covers all or part of the surface or all or part of the layer of the second material. As used herein, the term "layer" is not limited to a specific shape. Layers can be formed in the shape of a square, rectangle, hexagon, circle, ellipse, or any other arbitrary shape specified in the design. All layers of the electrochemical cell described herein are typically the same shape and can be formed by aligning and sealing the outer edges and corners of each layer. For the purposes of the present invention, it is not necessary to cover the entire surface of the second material with the first material layer. Components of the present invention, which are configured in a laminated or sandwich structure, are referred to as "layers" regardless of whether they cover the entire surface of adjacent components, and this explanation is simplified.

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

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

[0039] As used herein, the term "outer edge" refers to the boundary between an object, area, or surface and its outer periphery, the point or portion furthest from the center; therefore, the outer edge of an object extends downward along its outer circumference. For the purposes of this invention, the terms "periphery" and "outer edge" are used interchangeably. In practice, for example, the "peripheral edge" or "outer edge" of a single layer of a porous metal substrate layer typically has a measurable band width of about 1 mm to about 5 mm, but widths exceeding 5 mm are also considered the periphery or outer edge of a large cell (such as a cell of 10 cm × 10 cm or larger). The range of outer band widths roughly corresponds 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 single layer of solid material. Porosity is measured as the ratio or percentage of the void volume to the total volume occupied by the solid material.

[0041] As used herein, the terms "welding," "welded," or "welded sealing" refer to a manufacturing process in which multiple parts are simultaneously melted at high temperatures and then cooled to fuse the multiple parts together using metal materials or the like.

[0042] As used herein, the term "diffusion bonding" refers to a welding technique for joining similar metals to dissimilar metals. Diffusion bonding is a process based on the principle of solid diffusion, in which atoms on the surfaces of two solid metals disperse into each other within the other metal over time. Diffusion bonding is typically carried out in a combination of a high-temperature atmosphere with a material absolute melting temperature of approximately 50% to 75% and a pressurized process.

[0043] The high-density metal reinforcements of electrochemical cells exemplified herein refer to structural elements, i.e., foundational elements, that impart strength, weldability, and durability to the repeating structural units of the electrochemical cell. In this specification, a plurality of repeating structural units manufactured with high-density metal reinforcements of an electrochemical cell laminate is referred to as a "robust structure" cell laminate.

[0044] In this specification, the term "approximately" is used before the lower limit of a numerical range. Unless otherwise stated, the term "approximately" modifies both the lower and upper limits of a numerical range, intending to represent the acceptable range of variation between the lower and upper limits.

[0045] An exemplary embodiment of the present invention provides a novel porous reinforced metal substrate for use in an electrochemical cell having the following configurations (a) and (b). (a) A porous metal substrate comprising a layer forming a first side and a second side, having a porosity of approximately 20% to 50% by volume, and (b) A high-density metal reinforcement having a porosity of less than 20 volume%, arranged along at least a portion of the outer circumference of one side of a porous metal substrate.

[0046] Another exemplary embodiment of the present invention shows a metal-supported electrochemical cell with a robust structure comprising the following stacked configurations (a) to (c).

[0047] (a) Oxygen electrode,

[0048] (b) electrolytes;

[0049] (d) A porous metal substrate comprising a first side and a second side, configured as a single layer having a porosity of approximately 20% to 50% by volume, wherein the first side is positioned adjacent to the fuel electrode.

[0050] (c) Fuel electrodes, and

[0051] (e) A high-density metal reinforcement having a porosity of less than 20 volume%, disposed along at least a portion of the outer circumference of a second side of a porous metal substrate.

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

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

[0054] In yet another exemplary embodiment of the present invention, the thickness of the high-density reinforcing material is approximately 50 μm to 1000 μm.

[0055] The attached drawings will help to more clearly recognize and understand the present invention and its embodiments. Figure 1 shows a cross-sectional view of one embodiment of the present invention in which a porous metal substrate 4 is fixed to a metal reinforcing material 6 by welding or diffusion bonding technology, and a single electrochemical cell 10 is supported on the porous metal substrate 4. The electrochemical cell 10 shown in Figure 1 comprises a layered (sandwich) cell component including an oxygen electrode 1 (also called a "cathode"), an electrolyte 2, and a fuel electrode 3 (also called an "anode"). The fuel electrode 3 is fixed and supported on a porous metal substrate 14 comprising a porous metal substrate 4, and a reinforced (high-density) metal reinforcing material 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 positioned on the upper surface 7 of the porous metal substrate layer 4. Figure 2, which shows the porous metal substrate 4 viewed from the bottom of the electrochemical cell 10, shows the metal reinforcing material 6 positioned on the outer periphery 5 of the electrochemical cell 10.

[0056] The electrochemical cell 20 shown in Figure 3, which is a cross-sectional view of another embodiment of the present invention, comprises stacked cell components: an oxygen electrode 1, an electrolyte 2, and a fuel electrode 3. Again, the fuel electrode 3 is provided and supported on a porous metal substrate 14 which has a porous metal substrate layer 4 and whose outer edge is reinforced (densified), and a metal reinforcing material 6 is attached to the outer circumference of the bottom surface 8 of the porous metal substrate layer 4. In this embodiment, the metal reinforcing material 6 of the electrochemical cell 20 is attached along the outer edge of the porous metal substrate 4.

[0057] An electrochemical cell 30 of another embodiment of the present invention, shown in a cross-sectional view in Figure 4, comprises, similarly to Figure 3, a stacked cell component: an oxygen electrode 1, an electrolyte 2, and a fuel electrode 3. Again, the fuel electrode 3 is provided and supported on a porous metal substrate 14 having a porous metal substrate layer 4 and a reinforced (densified) outer edge, and a metal reinforcing material 6 is attached to the outer periphery of the bottom surface 8 of the porous metal substrate layer 4. In this embodiment, the metal reinforcing material 6 is attached along the outer edge of the porous metal substrate 4 and the outer edge of the fuel electrode 3. In yet another embodiment of the present invention (not shown), the metal reinforcing material 6 is attached along the outer edge of the porous metal substrate 4, the outer edge of the fuel electrode 3, and the outer edge of the electrolyte 2.

[0058] Metal substrates typically contain 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 metal substrates include ferritic and austenitic alloys primarily containing iron, about 10% to about 40% by weight of chromium, and small 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 small amounts of carbon, about 0.03% to about 0.16% by weight. A porous metal substrate according to one embodiment of the present invention includes a ferritic alloy. A porous metal substrate according to another embodiment of the present invention includes 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 gaseous components. The metal substrate typically has pores with a diameter or limit dimension of approximately 3 μm to 75 μm. The typical porosity of the metal substrate is approximately 20% to 50% by volume relative to the total volume of the porous metal substrate. The metal substrate is formed in a single layer with a plate thickness of approximately 80 μm (0.08 mm) to approximately 1000 μm (1 mm), preferably approximately 100 μm (0.1 mm) to approximately 500 μm (0.5 mm).

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

[0061] Metal reinforcements are typically formed with a low porosity from a material that is denser ("high-density") than a porous metal substrate. A metal reinforcement according to one embodiment of the present invention has a porosity of less than about 20 volume percent relative to the total volume of the 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 reinforcing members 6, provided as an integral frame in the electrochemical cell 10 shown in Figures 1 and 2, are provided along the outer edge or the entire outer circumference 5 of the porous metal substrate 4, and are attached to the outer edge of the bottom surface 8 of the porous metal substrate 4 opposite to the top surface 7 to which the fuel electrode (anode) 3 is attached. In other embodiments of the present invention, the strength and support capacity of the metal reinforcing members 6 can be further improved by providing reinforcing columns on the bottom surface 8 of the porous metal substrate 4. For example, columns of a cross shape or any other arbitrary geometric shape can be fixed to or across the bottom surface 8 of the porous metal substrate 4 to reinforce the outer circumference metal reinforcing members 6. In another exemplary embodiment of the present invention, the metal reinforcing members 6 are arranged along two parallel outer edges of the bottom surface 8 of the porous metal substrate 4, rather than around the entire circumference. In another exemplary embodiment of the present invention, the metal reinforcing members 6 are arranged at the four corners of the bottom surface 8 of the porous metal substrate 4, rather than around the entire circumference. The metal reinforcing members 6 serve as the base welding points when the laminate is assembled.

[0063] Metal reinforcements can be attached to porous metal substrates using any method known in the art, provided that no unacceptable deformation or damage occurs to the porous metal substrate. Two processing methods have been developed, (a) casting strip lamination and (b) metal ink printing, which enable the manufacture of porous reinforced metal substrates.

[0064] Figure 5 shows the casting strip lamination process. In this lamination process, a thin raw material frame reinforcement layer 12 is selected, and the reinforcement layer 12 is laminated to the outer circumference of the bottom surface of a porous metal sheet 11 containing a precursor for a porous metal substrate. Commercially available porous metal sheets 11 can be obtained from raw material manufacturers, but the raw material manufacturers use metal powder particles selected for the metal substrate, a given pore-forming agent that imparts a predetermined porosity and pore size to the metal substrate, and the desired reinforcing metal. In the heat-pressure lamination method shown in Figure 5, the reinforcement layer 12, which serves as a metal reinforcement, is laminated to the outer circumference of the porous metal sheet 11 by pressurization (direction of the vertical arrow) and heating. Typical heat-pressure conditions are a temperature of approximately 50°C to approximately 150°C and a pressure of approximately 30 lbs / sq in (30 psi, 206.8 kPa) to approximately 500 psi (3,447 kPa). A laminated structure 9 formed in a lamination process in a reducing atmosphere such as a mixed gas of hydrogen and an inert (unreactive) gas is co-sintered at a sufficient temperature to form a porous reinforced metal substrate 40 having a metal-reinforced high-density outer edge. The reducing atmosphere in one embodiment of the present invention contains about 1 volume% to about 20 volume% of hydrogen in an inert gas such as nitrogen or argon. An acceptable sintering process includes a step of heating from ambient temperature to a temperature of about 900°C to 1300°C. If necessary, one or more layers can be added to the metal reinforcement to laminate the metal reinforcement to a desired thickness. The porous reinforced metal substrate 40 of one embodiment of the present invention obtained by this lamination method comprises a metal substrate with a plate thickness of 0.27 mm bonded to a metal reinforcement with a material thickness of 0.47 mm.

[0065] Multiple layers are laminated to form a thick layer suitable for welding. Furthermore, the outer edge of the substrate can be reinforced to improve flatness. It is necessary to ensure acceptable substrate flatness to maintain good print quality of cell components. The present invention has the advantage of forming multiple layers substantially flat, allowing electrode layers to be tightly fixed onto the layers. The term "flat" refers to a flat surface formed by lines or trajectories that are substantially free of irregularities. The acceptable flatness range of the substrate is determined by visually inspecting the warping of the layers using an optical microscope with a magnification of approximately 10 to 20 times.

[0066] A second method for producing a porous reinforced metal substrate includes the step of screen printing a metal-reinforced ink onto the outer periphery of a porous metal substrate, followed by sintering the resulting ink-metal substrate composite. The metal-reinforced ink typically comprises a solvent, a binder, metal-reinforced composition particles, and a mixture of one or more optional plasticizers and dispersants. The solvent used for the metal-reinforced ink is selected from common volatile organic solvents. The amount of the organic solvent, typically selected from the group consisting of alcohols, esters, and ketones, is usually about 5% to 30% by weight relative to the total weight of the metal-reinforced ink. As a non-limiting example, the binder is selected from commercially available binder formulations containing cellulose compounds such as ethylcellulose. The amount of binder is about 5% to 30% by weight relative to the total weight of the metal-reinforced ink. The average particle size of the metal particles in the metal-reinforced ink is usually about 5 μm to about 25 μm. Suitable amounts of plasticizers are phthalate ester groups and glycol groups, typically added at about 1% to about 20% by weight relative to the total weight of the metal-reinforced ink. The appropriate amount of dispersant is a fish oil and amine-based dispersant added at a concentration of approximately 1% to 20% by weight relative to the total weight of the metal-reinforced ink. Depending on the desired weldability, the solid load and number of coats of the metal-reinforced ink are 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 approximately 1% to 20% by volume of hydrogen. An acceptable sintering process includes heating from ambient temperature to a temperature of approximately 900°C to 1300°C.

[0067] Figure 6 shows a perspective view of a repeating component unit ("repeating component unit") 50 of a metal-supported solid oxide fuel cell, which is useful for the laminate required for the construction of an electrochemical cell laminate. The repeating component unit 50 constituting the metal-supported solid oxide fuel cell ("fuel cell") 19 should be understood to include, for example, a multi-layer metal-supported electrochemical cell 10 as illustrated in Figures 1, 3, and 4. The fuel cell 19 can be welded to a metal frame 21 (also called a "metal spacer") which forms an additional layer to form a metal reinforcing member 6 of the fuel cell 19. The frame 21 usually has inlet and outlet passages for gas flow. The frame 21 shown in Figure 6 is fixed to a metal connection terminal 23 which forms an additional layer. Multiple gaseous fuel passages 27 are provided on the upper side 29 of the connection terminal 23 (shown in detail in Figure 1, for example) facing the metal reinforcing member 6 and the fuel electrode 3, and the fuel flow of usually hydrogen, carbon monoxide, or a mixture thereof supplied to the fuel electrode of the fuel cell 19 is supplied from the multiple gaseous fuel passages 27.

[0068] Figure 7 shows a perspective view of an embodiment of the repeating component unit 50 of the present invention, which represents the bottom surface 33 of the connection terminal 23, by rotating the repeating component unit of Figure 6 180 degrees on the horizontal axis. The bottom surface 33 of the connection terminal 23 is attached to the frame 21 facing the oxygen electrode of the adjacent fuel cell 19. An air passage 31 for supplying air, diluted oxygen, or pure oxygen to the oxygen electrode (reference numeral 1 in Figure 1) of the fuel cell is provided at the connection terminal 23.

[0069] The repeatable component unit of the metal-supported solid oxide fuel cell realized by the present patent applicant's novel outer perimeter metal reinforcement method has the technical advantage of obtaining robustness that contributes to vibration resistance, thermal circulation, and rapid startup. The interior can be hermetically sealed by welding the outer perimeter, and if airtight sealing is achieved, gaskets or glass seals are unnecessary. The fuel cell 19 can be fixed on the frame 21 by welding with the metal reinforcement material 6 (Figure 1).

[0070] The present invention is not limited to the use of specific fuel electrodes, electrolytes, or oxygen electrodes. A fuel electrode structure having a gaseous fuel passage 27 allows for the uniform flow of a reformed gas fuel, typically containing hydrogen and carbon monoxide, from inlet to outlet. High-strength cermet materials, which are mixtures of porcelain and metal manufactured using standard porcelain processing techniques, can typically be used to form fuel electrodes where electrical and ionic conductivity is required. Non-limiting examples of cermets useful as fuel electrode layers are composites of nickel or nickel oxide with metal oxides, 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 metal examples in one embodiment of the present invention include nickel yttria-stabilized zirconia, gadolinium-doped ceria-mixed nickel, and yttria-doped ceria-zirconia-mixed nickel.

[0071] Solid oxide electrolytes are formed from a dense porcelain layer that conducts oxide ions (O2). 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. Newly developed electrolytes that reduce resistance issues, improve the conductivity of oxide ions, and form a robust and high-performance electrolyte layer, as well as other applicable electrolytes, can also be used in this invention.

[0072] A porous elementary electrode that uniformly supplies oxygen flow throughout the acid electrode contains oxide ions (O 2 It is necessary to conduct ) into a solid oxide electrolyte. If A represents a substance selected from the group consisting of barium, strontium, lanthanum, samarium, praseodymium and combinations thereof, and B represents a substance selected from the group consisting of iron, cobalt, nickel, manganese and mixtures thereof, then a non-limiting example of a material for forming an oxygen electrode is represented by formula ABO3. 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 constituent 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 reinforcing member 6 is attached to the upper side of the frame 21, and a connecting terminal 23 is welded to the lower side of the frame 21 on the opposite side. The connecting terminal 23 is formed from a conductive material that is resistant to the heated and chemical environments it is exposed to, and it is necessary to maintain stabilization properties so that the connecting terminal 23, which is exposed to high temperatures on both the oxidation and reduction sides of the fuel cell 19, does not deteriorate. The connecting terminal 23 used in one embodiment of the present invention is formed from a metal plate or metal 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 connecting terminals of a specific thickness and material. In one embodiment of the present invention, a gaseous fuel passage 27 is optionally or as needed on the side of the connecting terminal 23 opposite to the frame 21, and a fuel gas flow is supplied to the fuel electrode 3 through the gaseous fuel passage 27. An oxygen or air passage for supplying oxygen or air flow to the oxygen electrode 1 is provided on the opposite side of the connecting terminal 23.

[0075] Non-limiting layers, which may be provided as needed or at will, are conventional composition layers. For example, an intermediate layer may be composed of a composition of added ceria (additives selected from Gd, Sm, Y, La, or mixtures thereof). In addition, barrier layers are usually provided to prevent the diffusion of elements from a particular layer to other layers. One example is a barrier layer containing a cermet blended with nickel and metal oxides, which is provided on the fuel electrode.

[0076] Although a finite number of embodiments of the present invention have been described in detail, it will be readily apparent that the present invention is not limited to the disclosed embodiments. Rather, even without description, the present invention can be modified to adopt any number of variations, alterations, substitutions, or equivalent configurations that are in line with the spirit and scope of the invention. It will also be understood that the various embodiments of the present invention described may include only a portion of the embodiments described. Accordingly, the present invention should not be limited to the foregoing description, but only to the appended claims.

Claims

1. (a) A porous metal substrate formed in one layer having a first side and a second side and having a porosity of 20% to 50% by volume, (b) A metal reinforcing material having a porosity of less than 20 volume percent is fixed to at least a portion of the outer circumference of one side of a porous metal substrate by welding or diffusion bonding, A porous reinforced metal substrate for use in an electrochemical cell, characterized in that the porous metal substrate and metal reinforcement are made of sintered materials.

2. The porous reinforced metal substrate according to claim 1, having pores with a diameter of 3 μm to 75 μm.

3. The porous metal substrate has a thickness of 80 μm to 1000 μm. The metal reinforcing material is a porous reinforced metal substrate according to claim 1, having a material thickness of 50 μm to 1000 μm.

4. The porous reinforced metal substrate according to claim 1, wherein the porous metal substrate and the metal reinforcement are each formed from materials separately selected from the group consisting of iron-chromium alloy, iron-nickel-chromium alloy, iron-cobalt alloy, iron-aluminum-chromium alloy, and chromium alloy.

5. The porous reinforced metal substrate according to claim 1, further comprising one or more metal support columns as a metal reinforcing material.

6. The porous reinforced metal substrate according to claim 1, wherein the metal reinforcing material is arranged along the entire circumference of the porous metal substrate, or along two parallel edges of the porous metal substrate, or at the corners of the porous metal substrate.

7. (a) A step of screen printing a metal-reinforced ink along at least a portion of the outer circumference of one side of a porous metal substrate having a porosity of 20% to 50% by volume to form a substrate-ink composite, (b) A method for producing a porous reinforced metal substrate according to claim 1, comprising the steps of: (b) sintering a substrate-ink composite having a porosity of 20 to 50 volume% to form a metal reinforcing material configured as a layer forming a first side and a second side; and forming a metal reinforcing material having a porosity of less than 20 volume% to be fixed along at least a portion of the outer circumference of one side of the substrate-ink composite by welding or diffusion bonding.

8. Metal-reinforced ink contains a solvent, binder, plasticizer, and reinforcing metal particles with a particle size of 5 μm to 25 μm. The manufacturing method according to claim 7, comprising the step of sintering a substrate ink composite in a reducing atmosphere containing hydrogen at a temperature of 900°C to 1300°C.

9. (a) A step of forming a base metal sheet containing substrate metal particles and a pore-forming agent that imparts a porosity of 20% to 50% by volume, and a step of forming a base metal reinforcement containing metal particles that become a metal reinforcement having a porosity of less than 20% by volume, (b) A step of forming a laminate by heating and pressurizing a raw metal reinforcing material on at least a portion of the outer circumference of one side of a raw metal sheet, (c) A method for producing a porous reinforced metal substrate according to claim 1, comprising the step of sintering a laminate at a temperature and pressure sufficient to form a reinforced porous metal substrate formed as a single layer having a first side and a second side and having a porosity of 20% to 50% by volume, and a metal reinforcing material fixed along at least a portion of the outer circumference of one side of the reinforced porous metal substrate by welding or diffusion bonding.

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

11. The following configuration (a) to (d) are arranged in layers, (a) Oxygen electrode, (b) electrolytes; (c) fuel electrode; (d) The porous reinforced metal substrate according to claim 1, The porous reinforced metal substrate comprises the following configurations (i) and (ii): (i) A porous metal substrate comprising a layer forming the first side and the second side, having a porosity of 20% to 50% by volume, (ii) A metal reinforcing material having a porosity of less than 20 volume percent, which is fixed by welding or diffusion bonding along at least a portion of the outer circumference of the second side of a porous metal substrate opposite to the first side adjacent to the fuel electrode. A metal-supported electrochemical cell having a robust structure characterized by a porous metal substrate and metal reinforcing material being sintered materials.

12. A metal-supported electrochemical cell having a robust structure according to claim 11, further comprising (a) an intermediate layer disposed between an oxygen electrode and (b) an electrolyte, and (c) a barrier layer disposed between a fuel electrode and (d) a porous metal substrate.

13. (d)(ii) The metal-supported electrochemical cell having a robust structure according to claim 11, further comprising an additional layer having a metal frame attached to a metal reinforcing material.

14. It further comprises an additional layer having connecting terminals that are attached to a metal frame, The metal-supported electrochemical cell having a robust structure according to claim 13, further comprising one or more gaseous fuel passages located on a first side adjacent to the metal frame, and one or more air passages or oxygen passages located on a second side of the connection terminal opposite to the first side.

15. The invention comprises a plurality of metal-supported electrochemical cells having a robust structure as described in claim 11, Each metal-supported electrochemical cell is an electrochemical cell stack that is either a metal-supported solid oxide fuel cell or a metal-supported solid oxide electrolytic cell.

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