Solid oxide electrolyzer cell including electrolysis-tolerant air-side electrode

Abstract

To provide a solid oxide electrolyzer cell (SOEC) with an electrolysis-tolerant air-side electrode.SOLUTION: A solid oxide electrolyzer cell (SOEC) includes a solid oxide electrolyte, a fuel-side electrode disposed on a fuel side of the electrolyte, and an air-side electrode disposed on an air side of the electrolyte. The air-side electrode includes a barrier layer disposed on the air side of the electrolyte and including a first doped ceria material, and a functional layer disposed on the barrier layer and including an electrically conductive material and a second doped ceria material.SELECTED DRAWING: None

Description

[Technical Field]

[0001] SUMMARY The present disclosure is directed generally to solid oxide electrolyzer cells, and more particularly to electrolyzer cells having electrolysis-resistant air-side electrodes. [Background technology]

[0002] Solid oxide reversible fuel cell (SORFC) systems can operate in a fuel cell mode to generate electricity by oxidizing fuel. SORFC systems can also operate in an electrolysis mode to generate hydrogen by electrolyzing water. However, prior art SORFCs can suffer from degradation of the air-side electrode due to the increase in cell voltage that can occur during the electrolysis process. Summary of the Invention

[0003] According to various embodiments, a solid oxide electrolyzer cell (SOEC) includes a solid oxide electrolyte, a fuel electrode disposed on a fuel side of the electrolyte, and an air electrode disposed on an air side of the electrolyte, the air electrode having a barrier layer disposed on the air side of the electrolyte and including a first doped ceria material, and a functional layer disposed on the barrier layer and including a conductive material and a second doped ceria material. [Brief explanation of the drawings]

[0004] [Figure 1A] FIG. 1A is a perspective view of an SOEC stack according to various embodiments of the present disclosure. [Figure 1B] FIG. 1B is a cross-sectional view of a portion of the stack of FIG. 1A. [Figure 2A] FIG. 2A is a plan view of the air side of an interconnect according to various embodiments of the present disclosure. [Figure 2B] FIG. 2B is a plan view of the fuel side of the interconnect of FIG. 2A. [Figure 3A] FIG. 3A is a plan view of the air side of an SOEC cell according to various embodiments of the present disclosure. [Figure 3B]FIG. 3B is a plan view of the fuel side of the SOEC cell of FIG. 3A. [Figure 4] FIG. 4 is a photograph showing delamination of the air electrode. [Figure 5] FIG. 5 is a cross-sectional view of an SOEC stack having electrolysis-resistant SOEC cells according to various embodiments of the present disclosure. [Figure 6A] FIG. 6A is a chart showing the degradation rate of the air electrode of an SOEC cell according to various embodiments of the present disclosure. [Figure 6B] FIG. 6B is a chart showing the degradation rate of the comparative SOEC cell. DETAILED DESCRIPTION OF THE INVENTION

[0005] Various embodiments will be described in detail with reference to the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts. References to specific examples and implementations are made for illustrative purposes and are not intended to limit the scope of the invention or the claims.

[0006] When an element or layer is referred to as being "on" or "connected to" another element or layer, it is understood that the element or layer can be directly on or connected to the other element or layer, or that there can be intervening elements or layers. In contrast, when an element is referred to as being "directly on" or "directly connected to" another element or layer, there are no intervening elements or layers. For purposes of this disclosure, it is understood that "at least one of X, Y, and Z" can be interpreted as X only, Y only, Z only, or any combination of two or more items of X, Y, and Z (e.g., XYZ, XYY, YZ, ZZ).

[0007] Where a range of values ​​is presented, unless the context clearly dictates otherwise, it is understood that each value between the upper and lower limits of that range, to one decimal place of the lower limit's unit, and any other stated or intervening value in that stated range, is encompassed within the invention. The upper and lower limits of these smaller ranges may independently be included within the smaller ranges and are also encompassed within the invention, subject to any specifically excluded limit within the stated range. When a stated range includes one or both of the limits, ranges excluding either or both of those included limits are also encompassed within the invention. It is also understood that the term "about" may refer to minor measurement errors, e.g., 5% to 10%. Additionally, as used herein, weight percent (wt%) and atomic percent (at%) refer to percent by total weight or percent by total number of atoms, respectively, of the corresponding composition.

[0008] Words such as "then," "then," and "next" are not necessarily intended to limit the order of steps, but rather these words may be used to guide the reader through the method description. Further, any reference to a claim element in the singular, for example, using the article "a," "an," or "the," should not be construed as limiting that element to the singular.

[0009] The term "electrolyzer cell stack" as used herein means a plurality of stacked electrolyzer cells which may optionally share a common water inlet and exhaust passage or riser. As used herein, an "electrolyzer cell stack" comprises a separate electrical entity with two end plates directly connected to the power conditioning and power (i.e., electrical) input of the stack, or forms part of an electrolyzer cell column with a terminal plate providing the electrical input.

[0010] Figure 1A is a perspective view of an electrolyzer cell stack 100 according to various embodiments of the present disclosure, and Figure 1B is a cross-sectional view of a portion of the stack 100 according to various embodiments of the present disclosure. With reference to Figures 1A and 1B, the stack 100 may be a solid oxide electrolyzer cell (SOEC) stack having solid oxide electrolyzer cells 1 separated by interconnects 10. With reference to Figure 1B, each electrolyzer cell 1 has an air electrode 3, a solid oxide electrolyte 5, and a fuel electrode 7.

[0011] Electrolyzer cell stacks are often assembled from a large number of electrolyzer cells 1 in the form of planar elements, tubes, or other shapes. Although the electrolyzer cell stack 100 in Figure 1A is arranged vertically, the electrolyzer cell stack can also be arranged horizontally or in any other orientation. For example, water can be supplied through water conduits 22 (e.g., water riser openings) formed in each interconnect 10 and electrolyzer cell 1, and oxygen can be supplied from the side of the stack between the air-side ribs of the interconnect 10.

[0012] Each interconnect 10 electrically connects adjacent electrolyzer cells 1 in the stack 100. In particular, an interconnect 10 may electrically connect the fuel electrode 7 of one electrolyzer cell 1 to the air electrode 3 of an adjacent electrolyzer cell 1. Figure 1B shows that the lower electrolyzer cell 1 is located between two interconnects 10. A Ni mesh (not shown) may be used to electrically connect the interconnect 10 to the fuel electrode 7 of the adjacent electrolyzer cell 1.

[0013] Each interconnect 10 has fuel-side ribs 12A that at least partially define fuel channels 8A and air-side ribs 12B that at least partially define oxidant (e.g., air) channels 8B. The interconnects 10 can function as separators to separate water flowing to the fuel electrode of one cell 1 in the stack from oxygen flowing from the air electrode of an adjacent cell 1 in the stack. Air or fuel end plates (not shown) can be present at either end of the stack 100.

[0014] Each interconnect 10 can be formed from or can contain a conductive material, such as a metal alloy (e.g., a chromium-iron alloy), that has a thermal expansion coefficient similar to that of the solid oxide electrolyte in the cell (e.g., a difference of 0% to 10%). For example, the interconnect 10 can contain a metal (e.g., a chromium-iron alloy, such as an alloy of 4 to 6 weight percent iron (e.g., 5 weight percent iron), optionally up to 1 weight percent yttrium, and the balance chromium) and can electrically connect the fuel electrode 7 of one electrolyzer cell 1 to the air electrode 3 of an adjacent electrolyzer cell 1.

[0015] FIG. 2A is a top view of the air side of an interconnect 10 according to various embodiments of the present disclosure, and FIG. 2B is a top view of the fuel side of the interconnect 10 according to various embodiments of the present disclosure. Referring to FIGS. 1B and 2A, the air side includes air channels 8B extending from opposing first and second edges of the interconnect 10. Oxygen flows through the air channels 8B from the air-side electrode 3 of the adjacent electrolyzer cell 1. A ring seal 20 surrounds the fuel holes 22A, 22B of the interconnect 10 to prevent water from contacting the air-side electrode 3. A band-shaped peripheral seal 24 is located on the peripheral portion of the air side of the interconnect 10. The seals 20, 24 can be formed of a glass or glass-ceramic material. The peripheral portion may be a raised plateau without ribs or channels. The surface of the peripheral region may be flush with the tops of the ribs 12B.

[0016] 1B and 2B, the fuel side of the interconnect 10 can have a fuel channel 8A and a fuel manifold 28. Water flows from one of the fuel holes 22A (e.g., an inlet fuel hole forming part of a fuel inlet riser) into the adjacent manifold 28, through the fuel channel 8A, and to the fuel-side electrode 7 of the adjacent electrolyzer cell 1. Excess water can flow into the other fuel manifold 28 and then into the outlet fuel hole 22B. A frame seal 26 is disposed in a peripheral region of the fuel side of the interconnect 10. The peripheral region can be a raised plateau that does not include ribs or channels. The surface of the peripheral region can be flush with the tops of the ribs 12A.

[0017] Figure 3A is a plan view of the air side of an electrolyzer cell 1 according to various embodiments of the present disclosure, and Figure 3B is a plan view of the fuel side of an electrolyzer cell 1 according to various embodiments of the present disclosure. With reference to Figures 1A, 2A, 3A, and 3B, the electrolyzer cell 1 can have inlet fuel holes 22A, outlet fuel holes 22B, an electrolyte 5, and an air electrode 3. The air electrode 3 can be positioned on the air side of the electrolyte 5. The fuel electrode 7 can be positioned on the opposite fuel (e.g., water) side of the electrolyte 5.

[0018] The fuel holes 22A, 22B can extend through the electrolyte 5 and can be positioned to overlap with the fuel holes 22A, 22B of the interconnect 10 when assembled into the electrolyzer cell stack 100. The air side electrode 3 can be printed on the electrolyte 5 so that it does not overlap with the ring seal 20 and the peripheral seal 24 when assembled into the electrolyzer cell stack 100. The fuel side electrode 7 can have a similar shape to the air side electrode 3. The fuel side electrode 7 can be positioned so that it does not overlap with the frame seal 26 when assembled into the stack 100. In other words, the electrodes 3 and 7 can be recessed from the edges of the electrolyte 5 so that corresponding edge regions of the electrolyte 5 can directly contact the corresponding seals 20, 24, 26.

[0019] In one embodiment, the electrolyzer cell stack 100 can operate only in electrolysis mode. Thus, the electrolyzer cell stack 100 does not operate in fuel cell mode to generate power from the fuel and air supplied to the fuel and air electrodes, respectively. Alternatively, the electrolyzer cell stack 100 can comprise a solid oxide regenerative (i.e., reversible) fuel cell (SORFC) stack. The SORFC can operate in a fuel cell (FC) mode (e.g., power generation mode) to generate electricity from the fuel and air supplied to the fuel and air electrodes, respectively, and in an electrolyzer cell (EC) mode (e.g., electrolysis mode) to produce hydrogen and oxygen from water supplied to the fuel electrode 7. In FC mode, oxygen ions are transported from the air (e.g., cathode) electrode 3 to the fuel (e.g., anode) electrode 7 of the SORFC to oxidize the fuel (e.g., a hydrocarbon fuel such as hydrogen and / or natural gas) and generate electricity. In EC mode, a positive potential is applied to the air side of the cell, and oxygen ions are transported from the water at the fuel electrode 7 through the electrolyte 5 to the air electrode 3. Water is then electrolyzed into hydrogen at the fuel electrode 7 and oxygen at the air electrode 3.

[0020] The air-side electrode 3 and fuel-side electrode 7 of the SORFC operate as a cathode and an anode, respectively, during the FC mode, and as an anode and a cathode, respectively, during the EC mode (i.e., a cathode in the FC mode is an anode in the EC mode, and an anode in the FC mode is a cathode in the EC mode). Thus, the SORFC described herein can be said to have an air-side electrode and a fuel-side electrode.

[0021] During EC mode, water in the fuel stream is reduced (H2O + 2e → O 2- +H2), H2 gas and O 2- ions are formed, and this O 2- The ions are transported through the solid electrolyte and then oxidized at the air electrode (O 2-(O2) is oxidized to produce molecular oxygen. Because the open circuit voltage of a SORFC operating on air and moist fuel (e.g., hydrogen and / or reformed natural gas) can be approximately 0.9 V to 1.0 V (depending on the moisture content), a positive voltage applied to the air electrode in EC mode raises the cell voltage to the normal operating voltage of approximately 1.1 V to 1.3 V. In constant current mode, the cell voltage may increase over time if there is cell degradation, which can be attributed to both ohmic sources and electrode polarization.

[0022] One of the major hurdles faced by current state-of-the-art solid oxide electrolyzer cells and SORFCs is the delamination of the air electrode at high current densities. The extent of delamination increases with current density and oxide ion transport flux. Without wishing to be bound by any particular theory, it is believed that delamination may be caused by oxygen precipitation at the electrolyte / cathode interface, which may lead to high pressures resulting in delamination of the air electrode.

[0023] Figure 4 is a photograph showing delamination of the air electrode 3 after operating a solid oxide electrolyzer cell in electrolysis mode at high current density for extended periods of time. As shown in Figure 4, the air electrode 3 can separate from the underlying electrolyte 5, as indicated by the dark area between them.

[0024] 5 is a cross-sectional view of an electrolyzer cell stack 500 having electrolysis-resistant solid oxide electrolyzer cells 502 according to various embodiments of the present disclosure. The electrolyzer cell stack 500 is similar to the stack 100 of FIGS. 1A-3B, and therefore only the differences from stack 100 will be described in detail.

[0025] Referring to FIG. 5, the electrolytic cell stack 500 can have at least one electrolytic cell 502 disposed between interconnects 10. The electrolytic cell 502 can operate only in the electrolysis mode (e.g., the cell can have a solid oxide electrolytic cell (SOEC)), or can operate in both the fuel cell mode and the electrolysis mode (e.g., the electrolytic cell 502 can have a SORFC). The electrolytic cell 502 has a solid oxide electrolyte 5, an air-side electrode 3 disposed on the air side of the electrolyte 5, and a fuel-side electrode 7 disposed on the fuel side of the electrolyte 5. In the fuel cell mode, air can be supplied to the air-side electrode 3 by the air channel 8B, and in the fuel cell mode, fuel can be supplied to the fuel-side electrode 7 by the fuel channel 8A. On the other hand, in the electrolysis mode, water can be supplied to the fuel-side electrode 7 by the fuel channel 8A.

[0026] Various materials can be used for the solid oxide electrolyte 5, the fuel-side electrode 7, and the air-side electrode 3. In various embodiments, the electrolyte 5 can include an ion-conductive material or an ion-conductive phase, such as stabilized zirconia, such as scandia-stabilized zirconia (SSZ), yttria-stabilized zirconia (YSZ), scandia-ceria-stabilized zirconia (SCSZ), scandia-ceria-yttria-stabilized zirconia (SCYSZ), scandia-ceria-ytterbia-stabilized zirconia (SCYbSZ), etc. Alternatively, the electrolyte 5 can include another ion-conductive material, such as doped ceria, such as samaria-doped ceria (SDC), gadolinia-doped ceria (GDC), or yttria-doped ceria (YDC), etc. In some embodiments, the electrolyte 5 can include a material represented by the formula: (ZrO2) 1-w-x-z (Sc2O3) w (CeO2) x (Y2O3) a (Yb2O3) b (where 0.09 ≦ w ≦ 0.11, 0 < x ≦ 0.0125, a + b = z, 0.0025 ≦ z ≦ 0.0125). In some embodiments, the electrolyte 5 is (ZrO2) 0.88 (Sc2O3)0.1 (CeO2) 0.01 (Yb2O3) 0.01 or (ZrO2) 0.88 (Sc2O3) 0.1 (CeO2) 0.01 (Y2O3) 0.01 Alternatively, the electrolyte 5 may contain (ZrO2) 0.89 (Sc2O3) 0.1 (CeO2) 0.01 may include:

[0027] The fuel-side electrode 7 may have a cermet layer including a metal-containing phase and a ceramic phase. The metal-containing phase may include a metal catalyst, such as nickel (Ni), cobalt (Co), copper (Cu), or alloys thereof, and serves as an electronic conductor. The metal catalyst may be in a metallic or oxidized state. For example, when the metal catalyst is in an oxidized state, it forms a metal oxide. Therefore, the fuel-side electrode 7 may be annealed in a reducing atmosphere prior to operation of the electrolyzer cell 1 to reduce the oxidized metal catalyst to the metallic state.

[0028] The metal-containing phase can consist solely of reduced nickel. When this nickel-containing phase is oxidized, it can form nickel oxide. Therefore, the fuel electrode 7 is preferably annealed in a reducing atmosphere prior to operation to reduce the nickel oxide to nickel.

[0029] The ceramic phase of the fuel electrode 7 can include, but is not limited to, gadolinia-doped ceria (GDC), samaria-doped ceria (SDC), ytterbia-doped ceria (YDC), scandia-stabilized zirconia (SSZ), ytterbia-ceria-scandia-stabilized zirconia (YbCSSZ), etc. As disclosed in U.S. Patent No. 8,580,456, which is incorporated herein by reference, in YbCSSZ, scandia can be present in an amount corresponding to 9 mol% to 11 mol%, e.g., 10 mol%, ceria can be present in an amount greater than 0 mol% (e.g., at least 0.5 mol%) and up to 2.5 mol%, e.g., 1 mol%, and at least one of yttria and ytterbia can be present in an amount greater than 0 mol% and up to 2.5 mol%, e.g., 1 mol%.

[0030] Furthermore, if necessary, an additional contact layer or current collector layer can be disposed on the fuel electrode 7. For example, a Ni or nickel oxide anode contact layer can be formed on the fuel electrode 7.

[0031] The air-side electrode 3 can have a barrier layer 30 disposed directly on the air side of the electrolyte 5, a functional layer 32 disposed on the barrier layer 30, and an optional current collector layer 34 disposed on the functional layer 32. Thus, the functional layer 32 is located between the barrier layer 30 and the current collector layer 34.

[0032] The barrier layer 30 can be sintered to the air side of the electrolyte 5. The barrier layer 30 can include, consist essentially of, or consist of a doped ceria material. For example, the barrier layer can include about 95 weight percent (wt %) to about 100 wt % doped ceria material, based on the total weight of the barrier layer 30. The doped ceria material can include samarium-doped ceria (SDC) and / or gadolinium-doped ceria (GDC).

[0033] SDC has the formula: Ce 1-x Sm x O 2-dwhere x ranges from 0.1 to 0.3. For example, certain SDC materials can be represented by the formula: Ce 0.8 Sm 0.2 O 2-d , Ce 0.9 Sm 0.1 O 2-d and Ce 0.7 Sm 0.3 O 2-d (wherein d is in the range of 0 to 0.2, for example, 0 to 0.1).

[0034] GDC is the formula Ce 1-x Gd x O 2-d where x is in the range of 0.1 to 0.3 and d is in the range of 0 to 0.2, e.g., 0 to 0.1. For example, certain GDC materials can be represented by the formula: Ce 0.9 Gd 0.1 O 2-d , Ce 0.8 Gd 0.2 O 2-d and Ce 0.7 Gd 0.3 O 2-d (wherein d is in the range of 0 to 0.2, for example, 0 to 0.1).

[0035] The functional layer 32 can include a mixture of a conductive material and a doped ceria material. The conductive material can be a conductive perovskite material, such as lanthanum strontium manganite (LSM), lanthanum strontium cobalt ferrite (LSCF), lanthanum strontium cobaltite (LSC), lanthanum strontium cobalt manganite (LSCM), lanthanum strontium ferrite (LSF), La 0.85 Sr 0.15 Cr 0.9 Ni 0.1O3(LSCN), combinations thereof, and the like. In some embodiments, the conductive material preferably includes LSM and / or LSCF. Alternatively, the conductive material may include a metal such as platinum. For example, the functional layer 32 may include about 10% to about 90% by weight of the above-mentioned conductive material and about 10% to about 90% by weight of a doped ceria material.

[0036] In various embodiments, the functional layer can include LSM as the conductive material. LSM has the formula: (La 1-z Sr z ) q MnO 3-d (wherein z is in the range of 0.1 to 0.4, q is in the range of 0.94 to 1, for example, 0.96 to 1, and d is in the range of 0 to 0.2). For example, LSM can be expressed by La 0.8 Sr 0.2 MnO 3-d , or (La 0.8 Sr 0.2 ) 0.98 MnO 3-d (wherein d is in the range of 0 to 0.1).

[0037] In some embodiments, the functional layer may include LSCF as the conductive material. LSCF has the formula: (La x Sr 1-x ) y Co z Fe 1-z O 3-δ (where x is in the range of 0.4 to 0.8, y is in the range of 0.94 to 1.0, z is in the range of 0.01 to 0.99, and δ is the equilibrium oxygen vacancy in the range of 0 to 0.1). For example, the LSCF can be expressed as 0.58 Sr 0.4 Co 0.2 Fe 0.8 O 3-δ , (La 0.6 Sr 0.4 ) 0.98 Co 0.2 Fe 0.8 O 3-δ Or (La 0.6Sr 0.4 ) 0.95 Co 0.2 Fe 0.8 O 3-δ where δ is the equilibrium oxygen vacancy.

[0038] The barrier layer 30 and the functional layer 32 may comprise the same or different doped ceria materials. For example, the barrier layer 30 may comprise GDC, and the functional layer 32 may comprise LSM and GDC, or LSM and SDC. In another embodiment, the barrier layer 30 may comprise SDC, and the functional layer 32 may comprise LSM and SDC, or LSM and GDC. In another embodiment, the barrier layer may comprise SDC, and the functional layer may comprise LSCF and SDC, or LSCF and GDC.

[0039] Without wishing to be bound by any particular theory, it is believed that the mixed oxide ionic and electronic conduction of the ceria phase of the barrier layer 30 reduces the overpotential at the interface between the barrier layer 30 and the functional layer 32. This reduction in overpotential can prevent delamination of the air electrode 3 from the electrolyte 5.

[0040] The current collector layer 34 may comprise a conductive material such as a conductive metal oxide, such as LSM, although other conductive perovskites, such as LSC, LSCM, LSCF, LSF, LSCN, etc., or metals such as Pt may also be used.

[0041] 6A is a chart showing the voltage change of a first embodiment SOEC cell and a second embodiment SOEC cell in an SOEC stack of one embodiment between the beginning of life and 17 current cycles of operation. FIG. 6B is a chart showing the voltage change of a comparative SOEC cell in a comparative SOEC stack under similar conditions between the beginning of life and 17 current cycles of operation. In both figures, the y-axis is the voltage change in volts, and the x-axis is the number of SOEC cells in each stack.

[0042] 6A and 6B, the SOEC cell of the first embodiment and the SOEC cell of the second embodiment have similar configurations, except that the SOEC cell of the first embodiment has an SDC barrier layer 30 and a GDC / LSM cathode functional layer 32, while the SOEC cell of the second embodiment has an SDC barrier layer 30 and an SDC / LSM cathode functional layer 32. The comparative SOEC cell does not have a barrier layer 30, but has a cathode functional layer including YSZ / LSM.

[0043] 6A and 6B, a larger cell voltage difference indicates a higher cell overpotential and, therefore, greater cathode degradation. As can be seen from the charts, the comparative SOEC cell exhibits a larger cell voltage difference (and thus an increased cell overpotential), while the cell of the present embodiment exhibits a substantially smaller cell voltage difference. Thus, it is expected that the doped ceria-based barrier layer and cathode functional layer materials provide unexpectedly improved protection against cell overpotential, thereby reducing delamination and / or general cathode degradation.

[0044] While the foregoing represents particularly preferred embodiments, it will be understood that the present invention is not limited thereto. Those skilled in the art will recognize that various modifications can be made to the disclosed embodiments and that such modifications are intended to be within the scope of the present invention. All publications, patent applications, and patents cited herein are incorporated herein by reference in their entirety.

Claims

1. a solid oxide electrolyte; a fuel-side electrode disposed on the fuel side of the electrolyte; an air-side electrode disposed on the air side of the electrolyte; 1. A solid oxide electrolyzer cell (SOEC) comprising: a barrier layer disposed on the air side of the electrolyte, the barrier layer including a first samarium-doped ceria (SDC) material as the first doped ceria material; a functional layer disposed on the barrier layer and comprising a conductive material and a second samarium-doped ceria material; a conductive perovskite current collector layer disposed on the air side of the functional layer opposite the barrier layer; and and the conductive material of the functional layer comprises lanthanum strontium cobalt ferrite (LSCF) represented by the formula (La x Sr 1-x ) y Co z Fe 1-z O 3-δ (wherein x is in the range of 0.4 to 0.8, y is in the range of 0.94 to 1.0, z is in the range of 0.01 to 0.99, and δ is an equilibrium oxygen vacancy in the range of 0 to 0.1); the second SDC material has the formula Ce 1-x Sm x O 2-d , where x is in the range of 0.1 to 0.3 and d is in the range of 0 to 0.2; The solid oxide electrolyzer cell (SOEC).

2. The first SDC material has the formula Ce １－ｘ Sm ｘ O ２－ｄ (wherein x is in the range of 0.1 to 0.3, and d is in the range of 0 to 0.2), The SOEC of claim 1.

3. The first SDC material is Ce ０．８ Sm ０．２ O ２－ｄ , Ce ０．９ Sm ０．１ O ２－ｄ or Ce ０．７ Sm ０．３ O ２－ｄ 3. The SOEC of claim 2 comprising: wherein d is in the range of 0 to 0.

1.

4. The SOEC of claim 1, wherein the conductive perovskite current collector layer comprises lanthanum strontium manganite (LSM), lanthanum strontium cobalt ferrite (LSCF), lanthanum strontium cobalt manganite (LSCM), lanthanum strontium ferrite (LSF), or lanthanum strontium nickel chromite (LSCN).

5. The LSCF is La ０．５８ Sr ０．４ Co ０．２ Fe ０．８ O ３－δ 2. The SOEC of claim 1, comprising:

6. The LSCF is (La ０．６ Sr ０．４ ) ０．９８ Co ０．２ Fe ０．８ O ３－δ 2. The SOEC of claim 1, comprising:

7. The LSCF is (La ０．６ Sr ０．４ ) ０．９５ Co ０．２ Fe ０．８ O ３－δ 2. The SOEC of claim 1, comprising:

8. The SOEC described in claim 4, wherein the conductive perovskite current collector layer includes the lanthanum strontium cobalt ferrite (LSCF).

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