Electrodes and Electrochemical Cells

Abstract

An electrochemical cell is disclosed having a porous metal support, a gas transport layer on the porous metal support, and an electrode layer on the gas transport layer. The gas transport layer is electrically conductive and has an open pore structure with a pore volume fraction of 20% or more, and the electrode layer has a pore volume fraction lower than the pore volume fraction of the gas transport layer. Also disclosed are stacks of such electrochemical cells and methods for making such electrochemical cells.

Description

[Technical Field]

[0001] The present invention relates to electrochemical cells, stacks of electrochemical cells, and methods of manufacturing such electrochemical cells. [Background technology]

[0002] Electrochemical cells formed from oxide layers, often known as solid oxide cells (SOC), can be used as fuel cells or electrolyzer / electrolysis cells.

[0003] SOC fuel cell units generate electricity by using an electrochemical conversion process to oxidize fuel. SOC cell units can additionally or alternatively operate as regenerative fuel cell (or reverse fuel cell) units, often known as solid oxide electrolyzer fuel cell units, for example, to separate hydrogen and oxygen from water or carbon monoxide and oxygen from carbon dioxide.

[0004] SOC units are typically ceramic-based and use an oxygen-ion-conducting metal oxide-containing ceramic as the electrolyte. SOCs tend to operate at high temperatures because many ceramic oxygen-ion conductors (e.g., doped zirconium oxide or doped cerium oxide) have useful ionic conductivity at temperatures above 500°C (for cerium oxide-based electrolytes) or 650°C (for zirconium oxide-based ceramics).

[0005] Solid oxide fuel cells (SOFCs) generate electrical energy through the electrochemical oxidation of a fuel gas (usually hydrogen-based). During operation, the electrolyte of a SOFC conducts oxygen ions from a cathode to an anode, located on either side of the electrolyte. The fuel, e.g., a fuel derived from the reforming of hydrocarbons or alcohols, is in contact with the anode (commonly known as the "fuel electrode"), and an oxidant, e.g., air or an oxygen-rich fluid, is in contact with the cathode (commonly known as the "air electrode").

[0006] A solid oxide electrolyzer cell (SOEC) may have the same structure as a SOFC, but is actually a SOFC that operates in reverse or regenerative mode to achieve the electrolysis of water and / or carbon dioxide.

[0007] Conventional ceramic-supported (e.g., anode-supported) SOCs have low mechanical strength and are prone to breakage. Therefore, metal-supported SOFCs, which have active fuel cell component layers supported on a metal substrate, have recently been developed. In these cells, the ceramic layers perform only electrochemical functions and can be very thin; that is, they are not self-supporting but rather a thin coating / film laid on and supported by a metal substrate. Such metal-supported SOC stacks are more robust and lower cost than ceramic-supported SOCs, have superior thermal properties, and can be sealed using conventional metal welding techniques.

[0008] Applicant's earlier patent application WO-A-2015 / 136295 discloses a metal-supported SOFC in which the electrochemically active layers (or active fuel cell component layers) include an anode layer, an electrolyte layer, and a cathode layer, each of which is deposited (e.g., as a thin coating / film) on and supported by a metal support plate (e.g., foil). The metal support plate has porous regions surrounded by non-porous regions, and the active layers are deposited on the porous regions such that gas can pass through the holes from one side of the metal support plate to the other to access the active layers coated thereon. The porous regions include individual openings (holes drilled in the metal foil substrate) that extend through the support plate and are located above the anode (or cathode, depending on the orientation of the electrochemically active layers). US-A-2007 / 0072070 discloses an electrochemical cell support structure including a conductive base defining a plurality of holes therethrough and a microporous cellular substrate disposed on the conductive base. US-A-2013 / 0124413 discloses a fuel cell incorporating a metallized gas diffusion layer. US-A-2011 / 0143254 discloses a fuel cell, a membrane electrode assembly, and a fuel cell process. CN-A-113667998 discloses a reversible SOEC with a porous metal support layer. US-A-2012 / 021332 discloses a dual-layer anode in an SOFC.

[0009] However, there remains a need to provide porous metal-supported electrochemical cells in SOFC or SOEC applications that have improved performance, especially at high current densities.

[0010] The present invention aims to address such needs. Summary of the Invention

[0011] Thus, in a first aspect, the present invention provides an electrochemical cell comprising a porous metal support, a gas transport layer on the porous metal support, and an electrode layer on the gas transport layer, wherein the gas transport layer is electrically conductive (e.g., in a reducing atmosphere) and has an open pore structure with a pore volume fraction of 20% or more, and the electrode layer has a pore volume fraction that is lower than the pore volume fraction of the gas transport layer.

[0012] This is advantageous because the gas transport layer simultaneously improves gas flow within the cell between the metal support and the electrode, provides mechanical support to the electrode, and provides electronic conductivity from the metal support to the electrode. The gas transport layer is located between the metal support and the electrode and has a pore volume fraction due to its microstructure, which can improve gas diffusion. The gas transport layer may allow the use of metal supports with lower porosity without adversely affecting SOFC or SOEC operation. SOFC or SOEC operation may be less prone to gas transport or diffusion limitation, especially at high current densities where mass flow rates can be large. This is particularly beneficial when lateral diffusion (e.g., diffusion parallel to the metal support between pores within the metal support) can be rate-limiting. This advantage is particularly applicable to the SOEC mode, where Knudsen transport effects make gas transport and concentration within the porous layer more limited.

[0013] The gas transport layer is preferably coated on a porous metal support.

[0014] The gas transport layer does not have to be disposed directly on the surface of the porous metal support; for example, there may be one or more layers (e.g., a barrier layer to inhibit corrosion) between the gas transport layer and the surface of the porous metal support.

[0015] The gas transport layer may comprise a conductive ceramic material. Suitably, the gas transport layer may comprise a perovskite material. Thus, the gas transport layer may comprise a doped perovskite material, optionally lanthanum strontium chromium manganite (La0.75 Sr 0.25 Cr 0.5 Mn 0.5 O 3-x ), doped SrTiO3, Y x Ca 1-x Cr y Co 1-y O 3-δ , Y 0.8 Ca 0.2 Cr 0.8 Co 0.2 O3(YCCC-SDC), Sr2Fe 1.5 Mo 0.5 O6MgMoO6, SrFe 0.2 Co 0.4 Mo 0.4 O3 (SFCM), PrBaMn2O5 (PBMO), and / or mixtures thereof, where x may be 0.4 to 0.9.

[0016] The doped SrTiO3 may include SrTiO3 doped with one or more dopants selected from Nb, Y, La, Ni, Ca, Fe, Ce, and optionally, the doped SrTiO3 is doped with La. 0.2 Sr 0.8 Ti 0.9 Ni 0.1 O3 or La 0.2 Sr 0.8 Ce 0.1 Ti 0.9 Ni 0.1 Contains O3(LSCNT).

[0017] Generally, the thickness of the gas transport layer can be 5 μm or greater, optionally 7 μm or greater, optionally 10 μm or greater, optionally 15 μm or greater, optionally 20 μm or greater, optionally 25 μm or greater, optionally 30 μm or greater, optionally 35 μm or greater, optionally 40 μm or greater.

[0018] The gas transport layer may have a thickness of 80 μm or less, optionally 70 μm or less, optionally 60 μm or less, optionally 50 μm or less, optionally 40 μm or less.

[0019] Thus, optionally the thickness of the gas transport layer may be in the range of 5 μm to 80 μm, optionally in the range of 10 μm to 40 μm.

[0020] Suitably, the pore volume fraction of the gas transport layer may be 22% or greater, optionally 25% or greater, optionally 30% or greater.

[0021] The pore volume fraction of the gas transport layer may be less than or equal to 75%, optionally less than or equal to 70%, and optionally less than or equal to 65%.

[0022] Thus, the pore volume fraction of the gas transport layer may be in the range of 20% to 75%, optionally in the range of 25% to 75%, and optionally in the range of 30% to 70%.

[0023] Pore ​​volume fraction may be measured by several methods, including 2D SEM imaging, focused ion beam scanning electron microscopy (FIB-SEM) tomography, X-ray computed tomography (CT), BET surface area analysis with gas (e.g., Ar, Kr, or N) adsorption, and / or Hg porosimetry.

[0024] Suitably, the average pore size of the gas transport layer may be 200 nm or greater, optionally 300 nm or greater, optionally 400 nm or greater.

[0025] The average pore size of the gas transport layer may be less than or equal to 1.5 μm, optionally less than or equal to 1.2 μm, optionally less than or equal to 800 nm, optionally less than or equal to 600 nm.

[0026] Thus, the average pore size of the gas transport layer may be in the range of 200 nm to 1.5 μm, optionally in the range of 300 nm to 1.5 μm, optionally in the range of 300 nm to 1.2 μm, optionally in the range of 300 nm to 1000 nm, optionally in the range of 400 nm to 800 nm, optionally in the range of 400 nm to 600 nm.

[0027] The electrode layer may comprise a different material than the gas transport layer.

[0028] The electrode layer may comprise doped ceria or doped zirconia.

[0029] Suitably, the electrode layer may comprise doped ceria gadolinium oxide (CGO) or yttria stabilized zirconia.

[0030] The electrode layer typically comprises a source of nickel, optionally nickel oxide. The electrode layer may comprise a nickel CGO cermet.

[0031] The thickness of the electrode layer may be 0.5 μm or more, optionally 0.8 μm or more, optionally 0.9 μm or more, optionally 1.1 μm or more, optionally 1.4 μm or more, optionally 1.8 μm or more, optionally 2 μm or more, optionally 2.2 μm or more, optionally 2.5 μm or more, optionally 2.8 μm or more, optionally 3 μm or more, optionally 5 μm or more, optionally 10 μm or more, optionally 15 μm or more.

[0032] The thickness of the electrode layer may be 60 μm or less, optionally 50 μm or less, optionally 45 μm or less, optionally 40 μm or less, optionally 35 μm or less, optionally 25 μm or less.

[0033] Thus, the thickness of the electrode layer may be in the range of 0.5 μm to 60 μm, in the range of 3 μm to 60 μm, in the range of 5 μm to 50 μm, and optionally in the range of 15 μm to 25 μm.

[0034] It may be advantageous to provide a relatively thin electrode layer. Thus, the thickness of the electrode layer may be in the range of 0.5 μm to 5 μm, optionally in the range of 0.5 μm to 4 μm, optionally in the range of 0.5 μm to 3 μm, optionally in the range of 0.5 μm to 2 μm, optionally in the range of 1 μm to 3 μm, optionally in the range of 2 μm to 3 μm.

[0035] The ratio of the thickness of the gas transport layer to the electrode layer may be 0.5 or greater, optionally 0.7 or greater, optionally 0.9 or greater, optionally 1.1 or greater, optionally 1.5 or greater, optionally 1.75 or greater, optionally 2 or greater, optionally 5 or greater, optionally 7 or greater, optionally 10 or greater, optionally 15 or greater, optionally 20 or greater, optionally 30 or greater, optionally 35 or greater.

[0036] The electrode may be a fuel electrode.

[0037] The electrochemical cell may further comprise an electrolyte layer on the electrode layer.

[0038] The electrolyte (which may be a multi-layer electrolyte system) may have an intermediate layer (e.g., an additional layer of electrode) between the electrode layer and the electrolyte, or the electrode layer may be in direct contact with (i.e., immediately adjacent to) a layer of electrolyte.

[0039] The electrolyte layer may optionally comprise doped ceria selected from samarium doped ceria (SDC), gadolinium doped ceria (GDC), praseodymium doped ceria (PDC), samaria gadolinia doped ceria (SGDC), and mixtures thereof.

[0040] The doped ceria may include cerium gadolinium oxide (CGO), which has the formula: Ce (1-x) Gd x O (2-0.5x-δ) wherein 0 <x≦0.5である。

[0041] The electrolyte layer may optionally comprise doped zirconia selected from scandia-stabilized zirconia (ScSZ), yttria-stabilized zirconia (YSZ), scandia-ceria-co-stabilized zirconia (ScCeSZ), ytterbia-stabilized zirconia (YbSZ), scandia-yttria-co-stabilized zirconia (ScYSZ), and mixtures thereof. The doped zirconia has the following formula: Zr (1-x) Yx O (2-0.5xδ) In the formula, 0 <x≦0.2である。

[0042] The electrolyte surrounds the GTL and electrode layers and may reduce or prevent gas leakage laterally through the GTL or electrode layers.

[0043] The electrochemical cell may further include a second electrode on the electrolyte layer. The second electrode may be an air electrode. The second electrode may include one or more layers.

[0044] The electrochemical cell may include a solid oxide electrochemical cell.

[0045] An electrochemical cell may be, or in use may be, a fuel cell or an electrolyzer (also called electrolysis) cell. In fuel cell mode, a fuel is in contact with the anode (fuel electrode) and an oxidant, such as air or an oxygen-rich fluid, is in contact with the cathode (air electrode), such that the air electrode is the cathode when operating in fuel cell mode. A solid oxide electrolyzer cell (SOEC) may have the same structure as a SOFC, but essentially operates the SOFC in a reverse or regenerative mode, for example, to achieve the electrolysis of water and / or carbon dioxide to produce hydrogen gas and / or carbon monoxide and oxygen.

[0046] Thus, the electrochemical cell may, in use, be an electrolysis cell.

[0047] Alternatively, the electrochemical cell may be a fuel cell or a reversible fuel cell in use.

[0048] As a further alternative, the electrochemical cell may be an oxygen separator or sensor.

[0049] The metal support may comprise an apertured metal foil (i.e., solid metal), which has the advantage that the porosity can be controlled and positioned in specific areas of the support.

[0050] The porous metal support may comprise steel, preferably stainless steel. Preferably, the porous metal support may comprise a perforated metal support, optionally a laser-perforated metal support. The porous metal support may have a barrier layer on its surface to reduce corrosion.

[0051] The ratio of the functional area of ​​the metal support to the area of ​​the pores (e.g., drilled holes) in the metal support may be 20 or more, optionally 50 or more, optionally 80 or more, optionally 100 or more, optionally 110 or more, optionally 120 or more, optionally 130 or more, optionally 140 or more, optionally 150 or more.

[0052] The ratio of the functional area of ​​the metal support to the area of ​​the pores (e.g., drilled holes) in the metal support may be 2500 or less, optionally 2000 or less, optionally 1500 or less, optionally 1000 or less, optionally 500 or less, optionally 250 or less.

[0053] Thus, in general, the ratio of the functional area of ​​the metal support to the area of ​​the pores (eg drilled holes) may be in the range of 20-2500.

[0054] The pore size of the pores (optionally drilled pores) in the metal support may be in the range of 5 μm to 50 μm, optionally in the range of 10 μm to 30 μm.

[0055] In some situations (e.g., when it is desired to further protect the metal support from corrosion), the porous metal support may be provided with a barrier layer on its surface, and the gas transport layer may be provided on the barrier layer.

[0056] The electrochemical cell according to the first aspect may be arranged as a stack of electrochemical cell units electrically connected in series.

[0057] Thus, in a second aspect, the present invention provides a stack of electrochemical cells, each electrochemical cell being in accordance with the first aspect.

[0058] The gas transport layer and the electrode layer may be deposited sequentially on the metal support by any suitable method.

[0059] Accordingly, in a third aspect, there is provided a method of manufacturing an electrochemical cell, the method comprising: providing a porous metal support; providing a precursor composition comprising at least one precursor of a porous, electrically conductive gas transport layer; applying the precursor composition to the porous substrate, optionally drying, and optionally sintering to form a conductive gas transport layer having a pore volume fraction of 20% or more; providing an electrode precursor composition comprising at least one precursor of an electrode layer; applying the electrode precursor composition to the gas transport layer, optionally drying, and optionally sintering to form an electrode layer on the gas transport layer, wherein the electrode layer has a pore volume fraction that is less than the pore volume fraction of the gas transport layer.

[0060] One or more steps of the method may be repeated.

[0061] The precursor composition may optionally further comprise a pore former comprising a material selected from poly(methyl methacrylate) (PMMA), graphite, carbon black, polystyrene, and / or mixtures thereof, which is advantageous because it allows for control of the pore volume fraction of the gas transport layer.

[0062] The precursors for the porous electrically conductive gas transport layer may have an average particle size of 200 μm or greater, optionally 250 μm or greater, and optionally 300 μm or greater.

[0063] The precursors for the porous electrically conductive gas transport layer may have an average particle size of 2000 μm or less, optionally 1800 μm or less, and optionally 1000 μm or less.

[0064] The precursor composition and / or electrode precursor composition may be applied to the porous substrate by printing, preferably by screen printing.

[0065] The optional sintering can be carried out at a temperature in the range of 750° C. to 1050° C., preferably in the range of 850° C. to 1050° C. The sintering can be carried out in an air atmosphere.

[0066] Thus, in a fourth aspect, there is provided an electrochemical cell obtainable by the method according to the third aspect.

[0067] In a fifth aspect, there is provided the use of an electrochemical cell according to the first aspect as an electrolyzer cell, or a stack of electrochemical cells according to the second aspect as an electrolyzer stack.

[0068] In a sixth aspect, there is provided the use of an electrochemical cell according to the first aspect as a fuel cell, or a stack of electrochemical cells according to the second aspect as a fuel cell stack. definition

[0069] As used herein, "lanthanoid," "lanthanide," and "Ln" are used interchangeably to refer to metallic chemical elements with atomic numbers 57-71.

[0070] As used herein, the term "dopant" is not limited to a maximum content of an element, ion, or compound added to a chemical structure. Similarly, the term "doping" refers to the addition of an amount of an element, ion, or compound to a material. It is not limited to a maximum amount of material beyond which the addition of material no longer constitutes doping.

[0071] The term "perovskite structure" as used herein generally refers to a single network of chemically bonded crystalline structures having a perovskite (ABX3) structure. This does not mean that this single network has a single uniform crystalline structure throughout the entire structure. However, when different crystalline structures exist between different regions of the network, these regions often have complementary structures, and chemical bonds are easily formed between them.

[0072] The term "solid oxide cell (SOC)" is intended to encompass both solid oxide fuel cells (SOFCs) and solid oxide electrolysis cells (SOECs).

[0073] The term "source of" an element, compound, or other material refers to a material that includes the element, compound, or other material, whether or not it is chemically bonded in the source. The source of the element, compound, or other material may be an elemental source (e.g., Ln, Sm, Gd, or O2) or may be in the form of a compound or mixture that includes the element, compound, or other material.

[0074] References to the porosity of the gas transport layer refer to the pore volume fraction, i.e., the volume of pores in the material relative to the total volume of the material, expressed as a percentage.

[0075] References herein to electrochemical cells, SOCs, SOFCs, and SOECs may refer to tubular or planar cells. Electrochemical cell units may be tubular or planar in configuration. Planar fuel cell units may be arranged on top of each other in a stacked configuration, e.g., a stack of 100-200 fuel cell units, and individual fuel cell units may be arranged electrically in series. Thus, references to a "stack of electrochemical cells" refer to multiple electrochemical cell units arranged electrically in series.

[0076] The electrochemical cell may be a fuel cell, a reversible fuel cell, or an electrolyzer cell. Generally, these cells may have a similar structure, and reference to an "electrochemical cell" (unless the context dictates otherwise) may refer to any of these types of cells.

[0077] The terms "oxidant electrode" or "air electrode" and "fuel electrode" are sometimes used interchangeably herein to refer to the cathode and anode, respectively, in a SOFC to avoid confusion between fuel cells and electrolyzer / electrolysis cells.

[0078] An electrochemical cell encompassed by the present invention may comprise: a) two flat components (e.g., a substrate with an electrochemical layer, an interconnector (separator plate)) welded with a fluid space between them, b) Three flat components welded together with a fluid space between them (e.g., a substrate with electrochemical layers, an interconnector (separator plate), and a spacer forming a fluid space).

[0079] As will be understood by those skilled in the art, the various features of the aspects of the present disclosure described herein may be used in combination with any other feature of the same or other aspects of the present disclosure, with appropriate modifications as necessary.

[0080] Furthermore, it is specifically contemplated that all aspects of the present invention or disclosure preferably "comprise" the features described in connection with that aspect, but may also particularly "consist" or "consist essentially" of the features outlined in the claims.

[0081] The present invention will now be described with reference to the accompanying drawings and examples. [Brief explanation of the drawings]

[0082] [Figure 1] 1 shows a graph of predicted cell overvoltage versus gas transport layer (GTL) thickness in SOEC mode. [Figure 2] 1 shows the predicted cell overpotential as a function of pore volume fraction and pore size for GTL. [Figure 3] 1 shows a graph of predicted cell voltage versus current density in fuel cell (positive current) and electrolysis cell (negative current) modes, with and without GTL, for standard metal support porosity. [Figure 4] Figure 4 shows graphs of cell voltage versus current density in fuel cell (positive current) and electrolysis cell (negative current) modes with and without GTL. The electrode area:pore area ratio in Figure 4 is 25 times that of Figure 3. [Figure 5] 1 shows an electron microscope photograph of the GTL layer of an electrochemical cell. [Figure 6] 10 shows a graph of cell voltage as a function of normalized current density for a cell at 600° C., 50%:50% H 2 :H 2 O according to the present disclosure. [Figure 7] 1 shows an electron microscope photograph of a portion of the GTL, electrode, and electrolyte layers of an electrochemical cell. [Figure 8] FIG. 1 is a schematic cross-sectional view of an electrochemical cell. DETAILED DESCRIPTION OF THE INVENTION

[0083] Figure 1 shows the SOEC mode (0.5 A / cm 2 This figure shows a graph of predicted cell overvoltage versus gas transport layer thickness for a 50% / 50% H2:H2O system (T=600°C, standard porosity) with a pore size of 800 nm and a pore volume fraction of 32%. The results of this analysis using a gas transport model suggest that the GTL thickness does not have a significant effect on cell overvoltage for thicknesses greater than 5 μm or 10 μm.

[0084] Figure 2 shows the predicted cell overpotential as a function of the pore volume fraction of the GTL (SOEC mode, 0.5 A / cm 2 , 50% / 50% H2:H2O, T = 600 °C). The results and analysis suggest that pore volume fraction and pore size improve gas transport. This effect on gas transport appears to gradually decrease as pore volume fraction exceeds 40% and pore diameter exceeds 600 nm.

[0085] Figure 3 shows the GTL (0.5A / cm 2 Figure 1 shows a graph of cell voltage versus current density to predict performance in fuel cell mode (positive current) and electrolysis cell mode (negative current) with and without a 50% / 50% H2:H2O catalyst (T=600°C). Typical metal support porosity has a ratio of functional area to pore area of ​​approximately 50-200. The functional area corresponds to the coated area of ​​the metal support available for electrochemical reaction.

[0086] Figure 4 shows the GTL (0.5A / cm 2 Figure 1 shows a graph of cell voltage versus current density to predict performance in fuel cell (positive current) and electrolysis cell (negative current) modes with and without GTL (50% / 50% H2:H2O, T=600°C). The porosity of the metal support is such that the ratio of electrode area (also called functional area) to pore area is 25 times higher than in the standard (Figure 3). Thus, the modeling results show that by using GTL, the required porosity of the metal support can be reduced without compromising activity.

[0087] Figure 5 shows the structure of lanthanum strontium chromium manganite (La 0.75 Sr 0.25 Cr 0.5 Mn 0.5 O 3-x 1 shows an electron micrograph of the GTL layer of an electrochemical cell in which a GTL 20 (of the same alloy) is disposed on a barrier layer 30 on a stainless steel metal support 10. A fuel electrode layer 40 of Ni:CGO is disposed on the GTL 20.

[0088] FIG. 6 shows the IV curve of a cell in a 50%:50% H:H O atmosphere at 6000° C., showing that the cell voltage can be up to 1.3 V at a normalized current density of 1, according to the present disclosure.

[0089] FIG. 7 shows an electron micrograph of a portion of the GTL, electrode, and electrolyte layers of an electrochemical cell. 0.75 Sr 0.25 Cr 0.5 Mn 0.5 O 3-x A GTL 20 made of Ni:CGO is disposed on a metal support (not shown). A fuel electrode layer 40 made of Ni:CGO is disposed on the GTL 20, and an electrolyte layer 50 made of GDC is disposed on the electrode layer.

[0090] Other suitable GTL layer materials include LSCrMn(La 0.75 Sr 0.25 )1-x Cr 0.5 Mn 0.5 O 3-δ , (doped with Nb, Y, La, Ni, Ca, Fe, Ce) SrTiO3, e.g., La 0.2 Sr 0.8 Ti 0.9 Ni 0.1 O3 or La 0.3 Sr 0.6 Ce 0.1 Ni 0.1 Ti 0.9 O3(LSCNT), Y 0.8 Ca 0.2 Cr 0.8 Co 0.2 O3, YCCC-SDC, Sr2Fe 1.5 Mo 0.5 O6, Sr2MgMoO6, double perovskite, PrBaMn2O5 (PBMO) A-site ordered perovskite, SrFe 0.2 Co 0.4 Mo 0.4 O3 (SFCM), or PrBaMn2O5 (PBMO) A-site ordered perovskite).

[0091] FIG. 8 shows a schematic cross-sectional view, not to scale, of an electrochemical cell 2, which may be an SOFC or SOEC. A ferritic stainless steel metal support 10 has a peripheral non-porous portion 14 and a central porous region 15 perforated with holes through the metal support 4. For example, lanthanum strontium chromium manganite (La 0.75 Sr 0.25 Cr 0.5 Mn 0.5 O 3-x ) is disposed on a barrier layer (not shown) on a metal support 10 made of ferritic stainless steel. A fuel electrode layer 40, for example, made of Ni:CGO, is disposed on the GTL 20, and an electrolyte layer 50 (which may have one or more layers, including, for example, a GDC layer) is disposed on the fuel electrode layer 40. The electrolyte layer 50 surrounds the GTL 20 and fuel electrode layer 40 and prevents gas flow laterally through the GTL 20 or fuel electrode layer 40 from the fuel side 80 to the air (oxidant) side 70, or vice versa. One or more layers (e.g., La0.99 Co 0.4 Ni 0.6 O (3-δ) A cathode layer 60, which may comprise a bulk layer of LCN 60, is disposed on the electrolyte layer 50.

[0092] The metal support 10 is provided with several laser-drilled holes, and the ratio of electrode area to hole area in this region ranges from 20 to 2500. This ratio refers only to the area within the "active" region of the substrate; it does not include areas of the substrate outside the drilled region (e.g., the edge of the substrate). If a reduction in the drilled area is desired in an SOFC, the use of the diffusion-optimized GTL described herein can achieve a ratio of 2500 without increasing the cell resistance compared to a standard cell without a GTL.

[0093] One method for determining pore volume fraction is 2D SEM imaging, in which the sample is cross-sectioned and imaged at high resolution with an SEM. Image processing is then used to separate the phases (i.e., GTL material and pores) and calculate the phase fractions. This is a convenient method. Another method is FIB-SEM tomography, in which a focused ion beam (FIB) is used to cut the material into slices and each slice is imaged with a scanning electron microscope (SEM). Image processing allows for 3D reconstruction and volumetric measurements of the pores / phases. This method is generally considered a high-resolution method. Example: Synthesis of a printable ink Dispersion and grinding of precursors

[0094] The lanthanum strontium chromium manganite (La 0.75 Sr 0.25 Cr 0.5 Mn 0.5 O 3-x ) GTL was prepared as follows.

[0095] The powder was weighed and mixed with a carrier, dispersant, and antifoaming agent to form a slurry containing a target amount of 70 wt% powder.

[0096] The slurry was transferred to a basket mill.

[0097] The slurry is 50 <0.25 μm and d 90 It was milled at approximately 7000 rpm for 4 hours until it achieved a particle size of <0.8 μm. The particle size distribution may be measured using a Malvern Mastersizer® 2000 laser diffraction particle size analyzer.

[0098] The slurry was then removed from the basket mill. Ink manufacturing

[0099] The dispersed and milled lanthanum strontium chromium manganite powder slurry prepared in the previous section was transferred to a small high shear disperser (HSD) pot and placed on the HSD.

[0100] An amount of binder powder equivalent to 1-3.5 wt% of the finished ink was weighed out.

[0101] The binder was added to the slurry, which was being actively dispersed with the HSD, and stirred until the binder was completely dissolved in the ink.

[0102] The ink was transferred to a triple roll mill (TRM) for final homogenization and passed through the mill four times with a 5 μm front nip, which ensured that the binder was fully homogenized into the ink and that no particles larger than 5 μm remained in the finished ink. Example 2: Printing of ink and formation of active layer

[0103] The target substrate consisted of a coated metal support with holes formed by laser drilling. The ink was screen printed in a single pass onto the metal support using an automated screen printer and then dried on a drying belt. The combination of ink solids content and screen mesh was chosen to result in a print thickness of approximately 15–20 μm. After the addition of the electrode and electrolyte layers, sintering was performed at temperatures between 900–1050 °C.

[0104] All publications mentioned in the above specification are incorporated herein by reference. Although exemplary embodiments of the present invention are disclosed in detail herein with reference to the accompanying drawings, it is understood that the present invention is not limited to the precise embodiments, and that various changes and modifications can be made by those skilled in the art without departing from the scope of the present invention as defined by the appended claims and their equivalents. [Explanation of symbols]

[0105] 2. Electrochemical Cell 10 Metal support 14 Non-porous portion of metal support 15 Porous portion of metal support 20 Gas Transport Layer (GTL) 30 Barrier Layer 40 Fuel electrode layer 50 electrolyte layer 60 Air electrode 70 Air (oxidant) side 80 Fuel side

Claims

1. 1. An electrochemical cell comprising: a porous metal support; a gas transport layer on the porous metal support; and an electrode layer on the gas transport layer, the gas transport layer is electrically conductive and has an open pore structure with a pore volume fraction of 20% or more, and the electrode layer has a pore volume fraction lower than the pore volume fraction of the gas transport layer; Electrochemical cell.

2. 10. The electrochemical cell of claim 1, wherein the gas transport layer comprises a conductive ceramic material.

3. 3. The electrochemical cell of claim 2 wherein the gas transport layer comprises a perovskite material.

4. The gas transport layer may be made of a doped perovskite material, optionally doped with strontium and manganese, such as lanthanum chromite, lanthanum strontium chromium manganate (La ０．７５ Sr ０．２５ Cr ０．５ Mn ０．５ O ３－ｘ ), doped SrTiO ３ , Y ｘ Ca １－ｘ Cr ｙ Co １－ｙ O ３－δ , Y ０．８ Ca ０．２ Cr ０．８ Co ０．２ O ３ (YCCC-SDC), Sr. ２ Fe １．５ Mo ０．５ O ６ MgMoO ６ , SrFe ０．２ Co ０．４ Mo ０．４ O ３ (SFCM), PrBaMn ２ O ５ 4. The electrochemical cell of claim 3, wherein the SiO 2 is selected from the group consisting of SiO 2 (PBMO), SiO 2 (PBMO), and / or mixtures thereof.

5. 5. The electrochemical cell of any one of claims 1 to 4, wherein the gas transport layer has a thickness of 5 μm or more, optionally 7 μm or more, optionally 10 μm or more, optionally 15 μm or more, optionally 20 μm or more, optionally 25 μm or more, optionally 30 μm or more, optionally 35 μm or more, optionally 40 μm or more.

6. 6. The electrochemical cell of any one of claims 1 to 5, wherein the gas transport layer has a thickness of 80 μm or less, optionally 70 μm or less, optionally 60 μm or less, optionally 50 μm or less, optionally 40 μm or less.

7. 7. The electrochemical cell of any one of claims 1 to 6, wherein the gas transport layer has a pore volume fraction of 22% or greater, optionally 25% or greater, and optionally 30% or greater.

8. 8. The electrochemical cell of any one of claims 1 to 7, wherein the gas transport layer has a pore volume fraction of 75% or less, optionally 70% or less, and optionally 65% ​​or less.

9. 9. The electrochemical cell of any one of claims 1 to 8, wherein the gas transport layer has an average pore size of 200 nm or greater, optionally 300 nm or greater, and optionally 400 nm or greater.

10. 10. The electrochemical cell of any one of claims 1 to 9, wherein the gas transport layer has an average pore size of 1.5 μm or less, optionally 1.2 μm or less, optionally 800 nm or less, optionally 600 nm or less.

11. 11. The electrochemical cell of claim 1, wherein the electrode layer comprises a different material than the gas transport layer.

12. 12. The electrochemical cell of claim 1, wherein the electrode layers comprise doped ceria or doped zirconia, and optionally doped ceria gadolinium oxide (CGO) or yttria stabilized zirconia.

13. 13. The electrochemical cell of claim 1, wherein the electrode layer comprises a source of nickel, and optionally nickel oxide.

14. 14. The electrochemical cell of claim 1, wherein the electrode layer comprises a nickel-CGO cermet.

15. 15. The electrochemical cell of any one of claims 1 to 14, wherein the electrode layer has a thickness of 3 μm or more, optionally 5 μm or more, optionally 10 μm or more, optionally 15 μm or more.

16. 16. The electrochemical cell of any one of claims 1 to 15, wherein the electrode layer has a thickness of 50 μm or less, optionally 45 μm or less, optionally 40 μm or less, optionally 35 μm or less.

17. 17. The electrochemical cell of claim 1, wherein the electrode is a fuel electrode.

18. 18. The electrochemical cell of any one of claims 1 to 17, further comprising an electrolyte layer on the electrode layer, optionally the electrolyte layer comprising doped ceria, optionally selected from samarium-doped ceria (SDC), gadolinium-doped ceria (GDC), praseodymium-doped ceria (PDC), samaria-gadolinia-doped ceria (SGDC), and mixtures thereof.

19. 19. The electrochemical cell of claim 1, further comprising a second electrode on the electrolyte layer, optionally the second electrode being an air electrode.

20. 20. An electrochemical cell according to any one of claims 1 to 19, wherein the porous metal substrate comprises steel, preferably stainless steel.

21. 21. The electrochemical cell of any one of claims 1 to 20, wherein the porous metal substrate comprises a perforated metal support, optionally a laser-drilled metal support.

22. 22. The electrochemical cell of any one of claims 1 to 21, wherein the ratio of the functional area of ​​the metal support to the area of ​​the pores in said metal support is 20 or more, optionally 50 or more, optionally 80 or more, optionally 100 or more, optionally 110 or more, optionally 120 or more, optionally 130 or more, optionally 140 or more, optionally 150 or more.

23. 23. The electrochemical cell of any one of claims 1 to 22, wherein the ratio of the functional area of ​​the metal support to the area of ​​pores in the metal support is 2500 or less, optionally 2000 or less, optionally 1500 or less, optionally 1000 or less, optionally 500 or less, optionally 250 or less.

24. 24. A stack of electrochemical cells, each electrochemical cell being as claimed in any one of claims 1 to 23.

25. providing a porous metal support; providing a precursor composition comprising at least one precursor of a porous, electrically conductive gas transport layer; applying the precursor composition to the porous substrate, optionally drying, and optionally sintering to form a conductive gas transport layer having a pore volume fraction of 20% or greater; providing an electrode precursor composition comprising at least one precursor of an electrode layer; forming an electrode layer on the gas transport layer by applying the electrode precursor composition onto the gas transport layer, optionally drying, and optionally sintering, wherein the electrode layer has a pore volume fraction that is less than the pore volume fraction of the gas transport layer. A method for manufacturing an electrochemical cell.

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