Electrode and electrochemical cell

Abstract

Disclosed is an electrochemical cell 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 comprising a pore volume fraction of 20% by volume or more, and wherein a pore volume fraction of the electrode layer is less than a pore volume fraction of the gas transport layer. Stacks of such electrochemical cells and methods of making the electrochemical cells are also disclosed.

Description

Technical Field

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

[0002] Electrochemical cells formed from oxide layers (often referred to as solid oxide cells: SOCs) can be used as fuel cells or electrolyzers / electrolysis cells.

[0003] The SOC fuel cell unit uses an electrochemical conversion process of an oxidized fuel to generate electricity. The SOC cell unit may also or alternatively operate as a regenerative fuel cell (or reverse fuel cell) unit, which is generally referred to as a solid oxide electrolyzer fuel cell unit, for example to separate hydrogen and oxygen from water or to separate carbon monoxide and oxygen from carbon dioxide.

[0004] SOC cells are typically ceramic based, using oxygen ion conducting metal oxide containing ceramics as electrolytes. Many ceramic oxygen ion conductors (e.g., doped zirconia or doped ceria) have usable ionic conductivity at temperatures exceeding 500°C (for ceria based electrolytes) or 650°C (for zirconia based ceramics), so SOCs are intended to operate at high temperatures.

[0005] Solid oxide fuel cells (SOFCs) generate electricity by electrochemically oxidizing a fuel gas (usually hydrogen-based). In operation, the electrolyte of the SOFC conducts oxygen ions from the cathode to the anode, which are arranged on opposite sides of the electrolyte. The fuel (e.g., a fuel from a recombinant hydrocarbon or alcohol) contacts the anode (commonly referred to as the "fuel electrode") and the oxidant (e.g., air or an oxygen-rich fluid) contacts the cathode (commonly referred to as the "air electrode").

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

[0007] Conventional ceramic supported (e.g. anode supported) SOCs have low mechanical strength and break easily. Therefore, metal supported SOCs with layers of active fuel cell components supported on a metal substrate have recently been developed. In these cells, the ceramic layers can be very thin since they only perform electrochemical functions: in other words, such ceramic layers are not self-supporting but thin coatings / films covering and supported by a metal substrate. Compared to ceramic supported SOCs, such metal supported SOC stacks are stronger, lower cost, have better thermal properties and can be sealed using conventional metal welding techniques.

[0008] The applicant's previous patent application WO-A-2015 / 136295 discloses a metal supported SOFC, wherein such electrochemically active layer (or active fuel cell component layer) comprises an anode, electrolyte and cathode layers respectively deposited (e.g. as a thin coating / film) on and supported by a metal support plate (e.g. a foil). The metal support plate has a porous region surrounded by a non-porous region, and such an active layer is deposited on the porous region so that gas can pass through such pores from one side of the metal support plate to the other side to reach the active layer coated thereon. The porous region comprises a plurality of separate small holes (holes drilled through the metal foil substrate) extending through the support plate overlapping the anode (or cathode, depending on the orientation of the electrochemically active layer). US-A-2007 / 0072070 discloses an electrochemical cell support structure, which comprises: a conductive base, which defines a plurality of holes through the conductive base; and a microporous porous substrate, which is disposed on the conductive base. US-A-2013 / 0124413 discloses a fuel cell with a plated metal 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 double-layer anode in a SOFC.

[0009] However, there is a need to provide porous metal supported electrochemical cells for SOFC or SOEC applications with improved performance, particularly at higher current densities.

[0010] The present invention aims to address this need. Summary of the invention

[0011] The present invention therefore provides, in a first aspect, an electrochemical cell comprising: a porous metal support; a gas transport layer located on the porous metal support; and an electrode layer located on the gas transport layer, wherein the gas transport layer is conductive (for example in a reducing environment) and has an open pore structure comprising a pore volume fraction of 20 vol% or more, and wherein the pore volume fraction of the electrode layer is smaller than the pore volume fraction of the gas transport layer.

[0012] This is advantageous because the gas transport layer effectively provides the function of improving the gas flow between the metal support and the electrode in the battery, the mechanical support of the electrode, and at the same time provides electronic conductivity from the metal support to the electrode. Because it is located between the metal support and the electrode and has a pore volume fraction from its microstructure, the gas transport layer allows enhanced gas diffusion. Providing the gas transport layer allows the use of a lower porosity metal support without adversely affecting the operation of the SOFC or SOEC. Especially at higher current densities with larger mass flows, the operation of the SOFC or SOEC tends to be less susceptible to gas transport or diffusion limitations. This is particularly advantageous when lateral diffusion (e.g., diffusion parallel to the metal support and between the pores of the metal support) is rate-limited. Such advantages can be particularly applied to the SOEC mode because the effect from Knudsen transport makes the gas transport and concentration in the porous layer more restrictive.

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

[0014] The gas transport layer may not be directly on the surface of the porous metal support; for example, there may be one or more layers (eg, a barrier layer to reduce 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 chrome manganite (La 0.75 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. x may be from 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 includes 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 O3(LSCNT).

[0017] Typically, the gas transport layer may have 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.

[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, the gas transport layer may optionally have a thickness in the range of 5 μm to 80 μm, optionally 10 μm to 40 μm.

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

[0021] The gas transport layer may have a pore volume fraction of 75% or less, optionally 70% or less, optionally 65% ​​or less.

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

[0023] The pore volume fraction can be determined by a variety of methods including 2D SEM imaging, focused ion beam-scanning electron microscopy (FIB-SEM) tomography, X-ray computed tomography (CT), BET surface area analysis of gas (e.g., Ar, Kr, or N2) adsorption, and / or Hg intrusion.

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

[0025] The gas transport layer may have 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.

[0026] Thus, the gas transport layer may have an average pore size of 200 nm to 1.5 μm, optionally 300 nm to 1.5 μm, optionally 300 nm to 1.2 μm, optionally 300 nm to 1000 nm, optionally 400 nm to 800 nm, optionally 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 ceria-doped gadolinium oxide (CGO) or yttrium-stabilised zirconia.

[0030] The electrode layer typically comprises a nickel source, which is optionally nickel oxide. The electrode layer may comprise nickel CGO ceramic.

[0031] The electrode layer may have a thickness of 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 electrode layer may have a thickness of 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 electrode layer may have a thickness in the range of 0.5 μm to 60 μm, 3 μm to 60 μm, 5 μm to 50 μm, optionally 15 μm to 25 μm.

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

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

[0036] The electrode may be a fuel electrode.

[0037] The electrochemical cell may also include an electrolyte layer disposed on the electrode layers.

[0038] The electrolyte (which may be an electrolyte system composed of multiple layers) may have an intermediate layer (eg, another electrode layer) between the electrode layer and the electrolyte, or the electrode layer may directly contact (ie, be in close proximity to) the electrolyte layer.

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

[0040] The doped cerium oxide may include cerium gadolinium oxide (CGO), which may be a cerium oxide having the chemical formula Ce (1-x) G x O (2-0.5x-δ) A solid solution, where 0 <x≤0.5。

[0041] The electrolyte layer may include doped zirconium oxide optionally selected from the group consisting of scandia stabilized zirconium oxide (ScSZ), yttria stabilized zirconium oxide (YSZ), scandia ceria co-stabilized zirconium oxide (ScCeSZ), ytterbium stabilized zirconium oxide (YbSZ), scandia yttria co-stabilized zirconium oxide (ScYSZ) and mixtures thereof. The doped zirconium oxide may be a zirconium oxide having the chemical formula Zr (1-x) Y x O (2-0.5x-δ) A solid solution, where 0 <x≤0.2。

[0042] The electrolyte layer may surround the GTL and electrode layers to reduce or prevent gas escape laterally through the GTL or electrode layers.

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

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

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

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

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

[0048] Another alternative is that the electrochemical cell may be an oxygen separator or sensor.

[0049] The metal support may comprise a metal foil (ie solid metal) provided with a plurality of holes. This has the advantage that the porosity can be adjusted and positioned in specific areas of the substrate.

[0050] The porous metal support may comprise steel, preferably stainless steel. Preferably, the porous metal support may comprise a drilled metal support, optionally a laser drilled metal support. The porous metal support may comprise 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 holes (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 holes (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, typically the ratio of the functional area of ​​the metal support to the area of ​​the holes (eg drilled holes) in the metal support may be in the range of 20 to 2500.

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

[0055] In certain cases (eg, when further protection of the metal support from corrosion is desired), the porous metal support may include a barrier layer on its surface and the gas transport layer may be located on the barrier layer.

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

[0057] Thus, in a second aspect, the present invention therefore provides a stack of electrochemical cells, wherein each electrochemical cell is an electrochemical cell according to the first aspect.

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

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

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

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

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

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

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

[0065] The optional sintering may be performed at a temperature in the range of 750° C. to 1050° C., preferably 850° C. to 1050° C. The sintering may be performed in an air environment.

[0066] In a fourth aspect, there is therefore provided an electrochemical cell obtainable by the method of the third aspect.

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

[0069] definition

[0070] In this specification, the terms "lanthanide", "lanthanum group element" and "Ln" are used interchangeably and refer to metallic chemical elements having atomic numbers of 57 to 71.

[0071] The term "dopant" as used herein is not intended to be limited to a maximum percentage of an element, ion, or compound added to a chemical structure. Similarly, the term "doping" is intended to mean adding a certain amount of an element, ion, or compound to a material. It is not limited to a maximum amount of material after which the addition of the material no longer constitutes doping.

[0072] The term "perovskite structure" as used herein refers to a chemically connected crystalline structure having a single network structure of a general perovskite (ABX3) structure. This does not mean that the single network structure needs to have a single, uniform crystalline structure throughout the structure. However, when different crystalline structures are produced between different regions of the network structure, it is often the case that these regions have complementary structures that allow chemical bonds to form more easily between them.

[0073] The term "solid oxide cell" (SOC) is intended to encompass solid oxide fuel cells (SOFCs) and solid oxide electrolysis cells (SOECs).

[0074] The term "source" of an element, compound, or other material refers to a material that contains the element, compound, or other material, whether or not chemically linked 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 contains the element, compound, or other material and includes one or more of these elements, compounds, or materials.

[0075] The porosity of the gas transport layer referred to here means the pore volume fraction, ie the volume of pores in the material relative to the overall volume of the material and expressed as a percentage.

[0076] In this specification, the electrochemical cells, SOC, SOFC and SOEC referred to may be tubular or planar cells. The electrochemical cell units may be tubular or planar structures. Planar fuel cell units may be arranged to overlap each other in a stack configuration, for example 100 to 200 fuel cell units in a stack, and such individual fuel cell units are arranged electrically in series. Therefore, the so-called "stack of electrochemical cells" refers to a plurality of electrochemical cells arranged electrically in series.

[0077] The electrochemical cell may be a fuel cell, a reversible fuel cell, or an electrolyzer cell. In general, these cells may have the same structure and reference to an electrochemical cell may refer (unless the context suggests otherwise) to any of these types of cells.

[0078] Because of possible confusion between a fuel cell or an electrolyzer / electrolysis cell, "oxidant electrode" or "air electrode" and "fuel electrode" are used herein and interchangeably to refer to the cathode and anode, respectively, of a SOFC.

[0079] The electrochemical cells encompassed by the present invention may comprise:

[0080] a) Two planar components welded together with a fluid volume between them (e.g. a substrate with an electrochemical layer and an interconnect (separating plates));

[0081] b) Three planar components welded together with a fluid volume between them (eg a substrate with electrochemical layers and interconnects (separating plates) and separators providing the fluid volume).

[0082] It will be appreciated by those skilled in the art that the various features of aspects of the disclosure described herein may be combined with any other features of the same or other aspects of the disclosure with appropriate modification, if desired.

[0083] Furthermore, while all aspects of the invention or disclosure preferably "comprise" the features described in connection with that aspect, it is specifically contemplated that they may "consist of" or "consist essentially of" those features set out in the claims.

[0084] The present invention is described below with reference to the accompanying drawings and examples. BRIEF DESCRIPTION OF THE DRAWINGS

[0085] Figure 1 Shown is a plot of the predicted cell overpotential versus gas transport layer (GTL) thickness for the SOEC mode.

[0086] Figure 2 A plot showing the predicted cell overpotential as a function of GTL pore volume fraction and pore size.

[0087] Figure 3Shown are plots of predicted cell voltage versus current density for electrodes with and without GTL in fuel cell (positive current) and electrolysis cell (negative current) modes at standard metal support porosity.

[0088] Figure 4 Shown are plots of cell voltage versus current density for electrodes with and without GTL in fuel cell (positive current) and electrolysis cell (negative current) modes. Figure 4 The ratio of electrode area:pore area in Figure 3 25 times that of CUHK.

[0089] Figure 5 An electron micrograph of the GTL layer of an electrochemical cell is shown.

[0090] Figure 6 A graph showing the voltage variation 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 is shown.

[0091] Figure 7 Electron micrographs of the GTL layer, the electrode layer and a portion of the electrode layer of an electrochemical cell are shown.

[0092] Figure 8 is a schematic cross-sectional diagram of an electrochemical cell. DETAILED DESCRIPTION

[0093] Figure 1 The results for SOEC mode (0.5A / cm 2 ; 50% / 50% H2 / H2O T=600°C, standard porosity) plotted against predicted cell overpotential for the gas transport layer. The pore size is 800nm ​​and the pore volume fraction is 32%. The results of this analysis using the gas transport model show that at thicknesses >5 or >10μm, the effect of the GTL thickness on the cell overpotential is relatively unimportant.

[0094] Figure 2 The predicted cell overpotential (SOEC mode; 0.5 A / cm2) is shown as a function of the GTL pore volume fraction. 2 ; 50% / 50% H2 / H2O T=600°C). The results and analysis show that pore volume fraction and pore size improve gas transport. The effect on gas transport seems to gradually decrease above 40% pore volume fraction and pore size of 600nm.

[0095] Figure 3 Plots of cell voltage versus current density are shown to predict the performance of electrodes with and without GTL in fuel cell (positive current) and electrolysis cell (negative current) modes (0.5 A / cm 2; 50% / 50% H2 / H2O T=600°C). Standard metal support porosity is a ratio of functional area to pore area of ​​about 50 to 200. The functional area corresponds to the coating area of ​​the metal support that can be electrochemically active.

[0096] Figure 4 Plots of cell voltage versus current density are shown to predict the performance of electrodes with and without GTL in fuel cell (positive current) and electrolysis cell (negative current) modes (0.5 A / cm 2 ; 50% / 50% H2 / H2O T = 600°C). The ratio of the electrode area (also called functional area) of the metal support porosity to the pore area is (e.g. Figure 3 Thus, the modeling results show that the GTL allows the required porosity of the metal support to be reduced without loss of activity.

[0097] Figure 5 Electron micrograph showing the GTL layer of an electrochemical cell, where lanthanum strontium chrome manganite (La 0.75 Sr 0.25 Cr 0.5 Mn 0.5 O 3-x ) 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.

[0098] Figure 6 An IV curve of a cell according to the present disclosure at 6000° C. with a 50%:50% H 2 :H 2 O environment is shown, which shows that the cell voltage can reach 1.3 V at a normalized current density of 1.

[0099] Figure 7 Electron micrograph showing the GTL layer, electrode layer, and a portion of the electrode layer of an electrochemical cell. 0.75 Sr 0.25 Cr 0.5 Mn 0.5 O 3-x ) is disposed on a metal support (not shown). A fuel electrode layer 40 of Ni:CGO is on the GTL 20 and an electrolyte layer 50 of GDC is on the electrode layer.

[0100] Other suitable GTL layer materials include: LSCrMn(La 0.75 Sr 0.25 ) 1-x Cr 0.5 Mn 0.5 O 3-δ ; such as La 0.2 Sr 0.8Ti 0.9 Ni 0.1 O3 or La 0.3 Sr 0.6 Ce 0.1 Ni 0.1 Ti 0.9 SrTiO3 (doped with Nb, Y, La, Ni, Ca, Fe, Ce) of 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.

[0101] Figure 8 A schematic cross-sectional view not to scale of an electrochemical cell 2 which may be a SOFC or SOED. A ferritic stainless steel metal support 10 has a peripheral non-porous portion 14 and a central porous portion 15 through which a plurality of holes have been drilled. For example, lanthanum strontium chromomanganite (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 ferritic stainless steel metal support 10. A fuel electrode layer 40 such as 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 the fuel electrode layer 40 to prevent gas from flowing laterally from the fuel side 80 through the GTL 20 or the fuel electrode layer 40 to the air (oxidant) side 70, or vice versa. It may have one or more layers (such as La 0.99 Co 0.4 Ni 0.6 O (3-δ) The air electrode layer 60 (the whole layer of LCN 60 ) is disposed on the electrolyte layer 50 .

[0102] The metal support 10 has a plurality of laser drilled holes to provide a ratio of electrode area to hole area in the region of 20 to 2500. This ratio relates only to the area in the "active" region of the substrate. It does not include the area of ​​the substrate outside the drilled area (e.g., the edges of the substrate). If it is desired to reduce the drilled area in a SOFC, the diffusion-optimized GTL described herein enables the cell to reach a ratio of 2500 before the resistivity is higher than a standard cell without the GTL.

[0103] Methods for determining the pore volume fraction include 2D SEM imaging. In this method, the sample is cross-sectioned and imaged on the SEM at high resolution. Imaging processing is then used to separate the phases (i.e., GTL material and pores) and calculate the phase fractions. This is a simple method. Other methods include FIB-SEM tomography, where a focused ion beam (FIB) is used to cut multiple pieces of material while each slice is imaged using a scanning electron microscope. The imaging process allows for 3D reconstruction and the volume of the pores / phases to be determined. This is generally considered a high resolution method.

[0104] Example: Synthesis of Printable Ink

[0105] Precursor dispersion and grinding

[0106] The lanthanum strontium chrome manganite (La 0.75 Sr 0.25 Cr 0.5 Mn 0.5 O 3-x )GTL was prepared as follows:

[0107] The powder was weighed and mixed with carrier, dispersant and defoamer to form a slurry containing a target amount of 70 wt% powder.

[0108] The slurry was sent to a basket mill.

[0109] The slurry was milled at approximately 7000 rpm for 4 hours until d 50 <0.25 μm and d 90 <0.8μm. This particle size distribution can be obtained using Malvern 2000 laser diffraction particle size analyzer was used for measurement.

[0110] The slurry was then removed from the basket mill.

[0111] Ink manufacturing

[0112] The dispersed and milled lanthanum strontium chrome manganite powder slurry made in the previous section was transferred to a small high shear disperser (HSD) box and placed on the HSD.

[0113] Binder powder was weighed in an amount corresponding to 1 to 3.5 wt % of the final ink.

[0114] The binder is added to the slurry actively dispersed on the HSD until the binder is completely dissolved in the ink.

[0115] The ink was transferred to a triple roll mill (TRM) for final homogenization and passed through the mill four times with a 5 μm top roll gap, ensuring that the binder was completely homogenized in the ink and no particles larger than 5 μm remained in the final ink.

[0116] Example 2: Printing ink and forming an active layer

[0117] The substrate comprises a coated metal support with laser drilled holes for porosity. The ink is screen printed on the metal support in a single pass using an automated screen printer. It is then dried on a drying belt. The combination of ink solids content and mesh size is selected to produce a print of approximately 15 to 20 μm thickness. After adding the electrode and electrolyte layers, sintering is performed at a temperature of 900 to 1050°C.

[0118] Reference numerals

[0119] 2 Electrochemical Cells

[0120] 10Metal support

[0121] 14Porous part of metal support

[0122] 15 Non-porous part of metal support

[0123] 20 Gas Transport Layer (GTL)

[0124] 30 Barrier Layer

[0125] 40 fuel electrode layer

[0126] 50 electrolyte layer

[0127] 60 air electrode

[0128] 70 Air (oxidant) side

[0129] 80 fuel side

[0130] All publications mentioned in the above specification are incorporated herein by reference. Although exemplary embodiments of the present invention have been disclosed herein in detail with reference to the accompanying drawings, it is to be understood that the present invention is not limited to the precise embodiments and that various changes and modifications may be made by those skilled in the art in the precise embodiments without departing from the scope of the present invention as defined by the appended claims and their equivalents.

Claims

1. An electrochemical cell comprising: a porous metal support; a gas transport layer located on the porous metal support; and an electrode layer located on the gas transport layer, The gas transport layer is conductive and has an open-pore structure, the open-pore structure includes a pore volume fraction of 20 volume % or more, and the electrode layer has a pore volume fraction smaller than that of the gas transport layer.

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

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

4. The electrochemical cell of claim 3, wherein the gas transport layer comprises a doped perovskite material, optionally selected from strontium and manganese doped lanthanum chromite, lanthanum strontium chromite (La 0.75 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.

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

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, optionally 65% ​​or less.

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 more, optionally 300 nm or more, optionally 400 nm or more.

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. The electrochemical cell of any one of claims 1 to 10, wherein the electrode layer comprises a different material than the gas transport layer.

12. The electrochemical cell according to any one of claims 1 to 11, wherein the electrode layer comprises doped ceria or doped zirconia, optionally wherein the electrode layer comprises doped ceria gadolinium oxide (CGO) or yttrium stabilized zirconia.

13. The electrochemical cell according to any one of claims 1 to 12, wherein the electrode layer comprises a nickel source, optionally nickel oxide.

14. The electrochemical cell of any one of claims 1 to 13, wherein the electrode layer comprises nickel CGO ceramic.

15. The electrochemical cell according to 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. 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. The electrochemical cell according to any one of claims 1 to 16, wherein the electrode is a fuel electrode.

18. The electrochemical cell according to any one of claims 1 to 17, further comprising an electrolyte layer located on the electrode layer, optionally wherein the electrolyte layer comprises doped cerium oxide, optionally selected from samarium doped cerium oxide (SDC), gadolinium doped cerium oxide (GDC), praseodymium doped cerium oxide (PDC), samarium gadolinium doped cerium oxide (SGDC) and mixtures thereof.

19. The electrochemical cell according to any one of claims 1 to 18, further comprising a second electrode located on the electrolyte layer, optionally wherein the second electrode is an air electrode.

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

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

22. The electrochemical cell of any one of claims 1 to 21, wherein the ratio of the functional area of ​​the metal support relative to the pore area in the 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. The electrochemical cell of any one of claims 1 to 22, wherein the ratio of the functional area of ​​the metal support relative to the pore area 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. A stack of electrochemical cells, wherein each electrochemical cell is an electrochemical cell according to any one of claims 1 to 23.

25. A method of manufacturing an electrochemical cell, the method comprising: providing a porous metal support; providing a precursor composition comprising at least one precursor for a porous and electrically conductive gas transport layer; applying the precursor composition to the porous substrate, optionally drying and optionally sintering, thereby forming a conductive gas transport layer having a pore volume fraction of 20 vol% or more; providing an electrode precursor composition comprising at least one precursor for an electrode layer; as well as The electrode precursor composition is applied to the gas transport layer, optionally dried and optionally sintered, thereby forming an electrode layer on the gas transport layer, the electrode layer having a pore volume fraction that is smaller than the pore volume fraction of the gas transport layer.

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