Solid oxide water electrolysis cell with stabilized internal oxygen partial pressure

Abstract

The present invention relates to a solid oxide water electrolysis battery in which a fuel electrode (cathode) layer, an electrolyte layer, and an air electrode (anode) layer are stacked in that order, wherein the electrolyte layer comprises an electrolyte composed of a solid solution (YSZN) containing yttria-stabilized zirconia (YSZ) and ceria (CeO₂).

Description

Solid oxide water electrolysis cell with stabilized internal oxygen partial pressure

[0001] The present invention relates to a solid oxide electrolysis cell (SOEC) capable of stabilizing the oxygen partial pressure within the electrolyte to prevent delamination of the anode-electrolyte interface even under high current density conditions, and improving electrochemical stability and durability during long-term operation.

[0002] Solid oxide electrolysis cells (SOECs) can operate at high temperatures (700 to 900°C), so they do not require expensive precious metal catalysts and have the advantage of high electrochemical efficiency. However, they have limitations in durability and lifespan due to thermal and chemical degradation caused by high-temperature operation.

[0003] In particular, if a high oxygen partial pressure is formed at the interface between the anode and the electrolyte under conditions of high water electrolysis current density, a failure phenomenon involving the delamination of the anode may occur; this is closely related not only to the operating conditions of the battery (temperature, current density, etc.) but also to the electron conductivity characteristics of the electrolyte and the oxygen ion transport capacity of the anode material.

[0004] The partial pressure of oxygen within the electrolyte is determined by the defect chemistry and oxygen ion conductivity of the electrolyte. Commonly used yttria-stabilized zirconia (YSZ) is a pure ion conductor with very low electron conductivity. While this characteristic is advantageous in terms of Faraday efficiency, under high current density water electrolysis conditions, the partial pressure of oxygen within the electrolyte rises sharply, which can lead to mechanical stress and the accumulation of oxygen gas at the air electrode interface. Consequently, the stability of the electrolyte-air electrode interface is reduced, and the electrochemical performance of the cell deteriorates during long-term operation.

[0005] Therefore, to improve the durability of solid oxide water electrolysis cells, new electrolyte compositions and structural design technologies are required to stabilize the oxygen partial pressure within the electrolyte and suppress the accumulation and delamination of oxygen gas at the air electrode interface.

[0006] The technical problem that the present invention aims to solve is to provide a high-temperature water electrolysis cell comprising an electrolyte of a novel composition that suppresses the high oxygen partial pressure generated within the electrolyte during the operation of the solid oxide water electrolysis cell to prevent delamination of the interface between the air electrode and the electrolyte, and ensures excellent electrochemical stability and durability even under high current density and long-term operating conditions.

[0007] To achieve the above technical objectives, the present invention provides a solid oxide water electrolysis cell in which a cathode layer, an electrolyte layer, and an anode layer are sequentially stacked, wherein the electrolyte layer comprises an electrolyte composed of a solid solution (YSZN) comprising yttria-stabilized zirconia (YSZ) and ceria (CeO2).

[0008]

[0009] The above electrolyte layer includes a solid solution electrolyte in which yttria-stabilized zirconia (YSZ) and ceria (CeO2) are dissolved, thereby effectively suppressing the rise in internal oxygen partial pressure compared to an electrolyte of YSZ single composition.

[0010] Conventional YSZ electrolytes, while possessing high oxygen ion conductivity, have very low electronic conductivity; consequently, under high current density conditions, the oxygen partial pressure within the electrolyte rises rapidly, making it prone to oxygen accumulation and delamination at the air electrode interface.

[0011] In contrast, the solid solution electrolyte included in the electrolyte layer of the solid oxide water electrolysis cell according to the present invention is Ce within the YSZ crystal lattice through the addition of ceria (CeO2). 4+ Ions are substituted, and Ce in the operating environment 4+ / Ce 3+ A fine N-type electron conduction pathway is formed as a result of the occurrence of a redox transition. This electron conduction pathway relieves charge imbalance within the electrolyte, thereby suppressing the rise in oxygen partial pressure, and at the same time optimizes the diffusion pathway of oxygen ions by controlling the concentration of oxygen vacancies.

[0012] Due to the above effects, the solid solution electrolyte (YSZN) included in the electrolyte layer of the solid oxide water electrolysis cell according to the present invention stabilizes the internal oxygen partial pressure at the level of the fuel electrode even under high current density operating conditions, and suppresses oxygen accumulation and delamination at the interface between the air electrode and the electrolyte, thereby greatly improving the long-term operating stability and durability of the cell.

[0013]

[0014] The solid solution electrolyte (YSZN) contained in the above electrolyte layer may have a composition represented by the following chemical formula.

[0015]

[0016] Chemical formula

[0017] xCeO2-(1-x)Y 0.08 Zr 0.92 O 2-d (0 < x ≤ 0.10)

[0018]

[0019] In the above chemical formula, d represents the oxygen vacancy concentration in the electrolyte, and Y 3+ Zr 4+ Substitution and Ce 4+ / Ce 3+ It is variably determined by electron transitions.

[0020]

[0021] The air electrode layer of the solid oxide water electrolysis cell according to the present invention may include an air electrode functional layer comprising LSM (Sr-doped LaMnO3) or LSCF (Sr, Co-doped LaFeO3) and an air electrode current collector layer (Anode Current Collector, ACC) formed on the air electrode functional layer.

[0022]

[0023] When the air electrode includes LSM as an active material, the air electrode functional layer may be composed of a mixture of LSM and YSZ, thereby minimizing the difference in the coefficient of thermal expansion at the air electrode-electrolyte interface and improving interfacial bonding.

[0024] In addition, the air electrode current collector layer may include LSM and carbon to improve the electrical conductivity and porosity control characteristics of the electrode.

[0025] By configuring the air electrode layer as described above, current collection efficiency can be improved while maintaining the chemical stability of the LSM air electrode during long-term operation of the water electrolysis cell.

[0026]

[0027] When the air electrode includes LSCF as an active material, the air electrode functional layer may include LSCF and GDC (Gd-doped CeO2).

[0028] In addition, the air electrode current collector layer includes LSCF and carbon to secure an electron conduction path and stabilize the pore structure.

[0029] Meanwhile, although LSCF provides high oxygen reduction reaction (ORR) activity and electron conductivity, insulators such as SrZrO3 may be formed when in direct contact with YSZ or YSZN electrolytes. Accordingly, it is desirable to interpose a buffer layer made of GDC between the air electrode functional layer and the electrolyte layer to suppress interfacial reactions and ensure chemical stability of the electrode-electrolyte interface.

[0030] By configuring the air electrode layer as described above, long-term operating stability can be improved while maintaining the high activity of the LSCF-based air electrode layer.

[0031]

[0032] In addition, the fuel electrode layer of the solid oxide water electrolysis cell according to the present invention may be composed of a fuel electrode support layer (Cathode Support, CS) and a fuel electrode functional layer (Cathode Functional Layer, CFL) formed on top of it.

[0033] The fuel electrode support layer acts as a mechanical support for the cell and is designed with a porous structure to facilitate the smooth diffusion of fuel gases, such as hydrogen or water vapor. The fuel electrode functional layer is the active layer where electrochemical reactions primarily occur, maximizing reaction efficiency by widening the interface with the electrolyte.

[0034] As an example, the fuel electrode support layer and the fuel electrode functional layer may be composed of a composite of NiO and YSZ. NiO is converted to metallic nickel (Ni) under reducing conditions to provide excellent electrical conductivity, while YSZ forms oxygen ion conduction pathways to improve the uniformity of the electrochemical reaction. The Ni-YSZ composite balances electrochemical activity, mechanical strength, and thermal shock resistance during high-temperature operation, thereby serving to ensure the long-term reliability and durability of the solid oxide water electrolysis cell.

[0035]

[0036] In addition, in another aspect of the invention, the present invention provides a solid oxide water electrolysis cell stack comprising a plurality of unit cells made of the solid oxide water electrolysis cells.

[0037] Each unit cell comprising the solid oxide water electrolysis cell according to the present invention is electrically connected in series or parallel to improve the current capacity and hydrogen production efficiency of the entire stack. When configured as a stack structure, electrical contact resistance between cells is minimized, and thermal uniformity is ensured, enabling stable operation for a long time. Therefore, the solid oxide water electrolysis cell stack according to the present invention can simultaneously achieve high electrochemical efficiency and durability even under high temperature and high current conditions.

[0038] The solid oxide water electrolysis cell according to the present invention effectively suppresses localized oxygen accumulation and delamination at the interface between the air electrode and the electrolyte by stabilizing the oxygen partial pressure within the electrolyte through an electrolyte (YSZN) formed by adding ceria (CeO2) to a yttria-stabilized zirconia (YSZ) electrolyte. Accordingly, thermal and mechanical degradation of the air electrode-electrolyte interface can be prevented even under high current density and long-term operating conditions, and the electrochemical stability and durability of the cell are significantly improved compared to conventional technology. Furthermore, despite a slight increase in electronic conductivity due to the addition of ceria (CeO2), the decrease in Faraday efficiency is minimal, and the effect of suppressing internal oxygen partial pressure is stably maintained regardless of the type of air electrode material.

[0039] FIG. 1 is a schematic diagram showing the manufacturing sequence of a solid oxide water electrolysis cell (YSZN cell) with stabilized internal oxygen partial pressure according to an embodiment of the present invention.

[0040] Figure 2 is a graph showing the change in electrode potential and oxygen partial pressure inside the electrolyte according to the change in current density of a cell (applied with LSM air electrode and YSZ electrolyte) according to a comparative example.

[0041] Figure 3 is a graph showing the change in internal electrode potential and oxygen partial pressure of the electrolyte during long-term operation (50 hours) of a cell according to a comparative example (applied with LSM air electrode and YSZ electrolyte).

[0042] Figure 4 is a graph showing the change in electrode potential and oxygen partial pressure inside the electrolyte according to the change in current density of a cell (applied with LSM air electrode and YSZN electrolyte) according to an embodiment of the present invention.

[0043] Figure 5 is a graph showing the change in internal electrode potential and oxygen partial pressure of the electrolyte during long-term operation (50 hours) of a cell (applied with LSM air electrode and YSZN electrolyte) according to an embodiment of the present invention.

[0044] Figure 6 is a graph showing the change in electrode potential and oxygen partial pressure inside the electrolyte according to the change in current density of a cell (applied with LSCF air electrode and YSZ electrolyte) according to a comparative example.

[0045] Figure 7 is a graph showing the change in internal electrode potential and oxygen partial pressure of the electrolyte during long-term operation (50 hours) of a cell according to a comparative example (applied with LSCF air electrode and YSZ electrolyte).

[0046] FIG. 8 is a graph showing the change in electrode potential and oxygen partial pressure inside the electrolyte according to the change in current density of a cell (applied with LSCF air electrode and YSZN electrolyte) according to an embodiment of the present invention.

[0047] FIG. 9 is a graph showing the change in internal electrode potential and oxygen partial pressure of the electrolyte during long-term operation (50 hours) of a cell (applied with LSCF air electrode and YSZN electrolyte) according to an embodiment of the present invention.

[0048] In describing the present invention, if it is determined that a detailed description of related known functions or configurations could unnecessarily obscure the essence of the invention, such detailed description will be omitted.

[0049]

[0050] Since embodiments according to the concept of the present invention may be subject to various modifications and may take various forms, specific embodiments are illustrated in the drawings and described in detail in this specification or application. However, this is not intended to limit embodiments according to the concept of the present invention to specific disclosed forms, and it should be understood that they include all modifications, equivalents, and substitutions that fall within the spirit and scope of the present invention.

[0051]

[0052] The terms used herein are merely for describing specific embodiments and are not intended to limit the invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In this specification, terms such as “comprising” or “having” are intended to specify the existence of the described features, numbers, steps, actions, components, parts, or combinations thereof, and should be understood as not precluding the existence or addition of one or more other features, numbers, steps, actions, components, parts, or combinations thereof.

[0053]

[0054] The present invention will be explained in more detail below through examples.

[0055]

[0056] The embodiments according to this specification may be modified in various different forms, and the scope of this specification is not to be interpreted as being limited to the embodiments described below. The embodiments of this specification are provided to more fully explain this specification to those with average knowledge in the art.

[0057]

[0058] <Example>

[0059] The steps (1) to (5) below were performed sequentially to manufacture an internal oxygen partial pressure stabilization type solid oxide water electrolysis cell (YSZN cell) according to the present invention.

[0060]

[0061] (1) Preparation of fuel electrode (cathode support / cathode functional layer) powder and slurry

[0062] 1) Cathode Support powder - Powdered NiO and YSZ were mixed in a 7:3 weight ratio. Then, carbon was added to the NiO and YSZ mixture in a 10:1 weight ratio, and wet ball milling was performed using ethanol along with zirconia balls 10Φ. The prepared solution was dried on a hot plate at 50°C at 200 rpm. The dried powder was sieved using a 150 µm sieve.

[0063] 2) Cathode Functional Layer (CFL) slurry - Powdered NiO and YSZ were mixed in a weight ratio of 3:2. Then, the NiO and YSZ mixture, distilled water, and 1Φ zirconia balls were placed in a zirconia pot, and planetary ball milling was performed. The prepared CFL powder was added to butanol to prepare the CFL slurry.

[0064]

[0065] (2) Preparation of electrolyte slurry

[0066] YSZN ((CeO2) 0.08 (Y 0.08 Zr 0.92 O 2-d ) 0.92) slurry - CeO2 was used in combination with YSZ, which has high stability and oxygen ion conductivity at high temperatures, to increase N-type conductivity. CeO2 powder and 8YSZ powder were mixed in an 8:92 molar ratio, then mixed with butanol and dispersed using a sonicator to prepare a slurry.

[0067]

[0068] (3) Preparation of air electrode (anode functional layer / anode current collector) powder and paste

[0069] 1) Anode Functional Layer (AFL) paste - La, which is stable with YSZ and has high electronic conductivity at high temperatures 0.8 Sr 0.2 MnO 3-δ When using LSM, LSM and YSZ were mixed in a 1:1 weight ratio to improve ion transport performance, and then ball milling was performed by adding ethylene glycol and 5Φ zirconia balls. La, which exhibits both ionic and electronic conductivity at high temperatures and has a faster ORR reaction compared to LSM, 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3-δ When using (LSCF), to improve the coefficient of thermal expansion and performance with the buffer layer GDC, LSCF and GDC were mixed in a weight ratio of 3:2, and then ethylene glycol and 5Φ zirconia balls were added to perform ball milling.

[0070] 2) Anode Current Collector (ACC) paste - To create a porous structure for both LSM and LSCF, LSM and LSCF were mixed with carbon in a weight ratio of 10:1, respectively, and then ball milling was performed by adding ethylene glycol and 5Φ zirconia balls.

[0071]

[0072] (4) Buffer Layer Ink Paste Preparation

[0073] Buffer Layer ink - LSCF reacts with YSZ, which is used as an electrolyte material, to form an insulator such as SrZrO3. To suppress this side reaction, an ink paste was prepared by performing 3-roll milling of GDC (Gd-doped Ceria) and an ink vehicle to coat GDC onto the electrolytes YSZ and YSZN.

[0074]

[0075] (5) Cell manufacturing for performance evaluation of the present invention (Fig. 1)

[0076] 1) Preparation of Cathode support layer: 2.5g of NiO+YSZ powder was placed in a mold made of 30Φ diameter and molded into a disc pellet shape by applying pressure with an oil pressure machine, and then heat-treated at 950℃.

[0077] 2) Preparation of Cathode functional layer: 500 µL of CFL slurry was applied to the cathode support using a micropipette and then heat-treated at 950°C.

[0078] 3) Preparation of YSZN electrolyte layer: 1300 µL of YSZN electrolyte slurry was applied to the CFL using a micropipette and coated, then sintered at 1460°C.

[0079] 4) Preparation of Buffer layer: When using LSCF as the anode, to prevent side reactions, a buffer layer was coated with GDC ink on the sintered electrolyte layer using a screen printer and then heat-treated at 1300℃.

[0080] 5) Preparation of anode functional layer: In the case of LSM, AFL paste was coated onto the sintered electrolyte layer using a screen printer and then heat-treated at 1150°C, and in the case of LSCF, AFL paste was coated onto the heat-treated GDC Buffer layer using a screen printer and then heat-treated at 1100°C.

[0081] 6) Preparation of anode current collector: In the case of LSM, ACC paste was coated onto AFL using a screen printer and then heat-treated in a furnace at 1150°C, and in the case of LSCF, ACC paste was coated in the same manner and then heat-treated in a furnace at 1100°C.

[0082]

[0083] <Comparative Example>

[0084] A high-temperature water electrolysis cell (YSZ cell) in which the electrolyte layer is composed only of YSZ was manufactured by performing steps (1) to (5) in the same manner as in the example, except that when preparing the electrolyte slurry, ceria (CeO2) was not added to YSZ and a slurry containing only YSZ was prepared.

[0085]

[0086] <Experimental Example>

[0087] A solid oxide water electrolysis cell with a four-electrode system was fabricated using a YSZN electrolyte cell according to an embodiment of the present invention and a YSZ electrolyte cell according to a comparative example. The cell structure has a platinum (Pt) probe electrode inserted into the electrolyte and an LSM (LSM AFL) reference electrode formed on the surface, allowing for real-time measurement of the oxygen partial pressure inside the electrolyte in response to changes in current density.

[0088]

[0089] Figure 2 shows a current density of 0.6 A / cm² at OCV. 2 The results show the air electrode-fuel electrode voltage (V1) and embedded probe-reference electrode voltage (V2) of a cell (LSM / YSZ cell) according to a comparative example using an LSM anode and YSZ electrolyte, applied up to [amount]. It was confirmed that as the current density increased, the oxygen partial pressure inside the electrolyte (at the probe location) increased rapidly from 0.1145 atm to 187.1 atm.

[0090]

[0091] Figure 3 shows the results of measuring the air electrode-fuel electrode voltage (V1) and the embedded probe-reference electrode voltage (V2) while operating a cell (LSM / YSZ cell) according to a comparative example with an LSM anode and YSZ electrolyte for 50 hours. As the operating time of the cell progressed, the embedded probe-reference electrode voltage (V2) gradually increased and then showed unstable changes. This means that the oxygen partial pressure inside the electrolyte increased rapidly, and the maximum value exceeded the delamination critical oxygen partial pressure (27,500 atm) of the YSZ electrolyte, suggesting that delamination occurred at the interface between the air electrode and the electrolyte. At the same time, the air electrode-fuel electrode voltage (V1) also showed a tendency to increase rapidly, indicating that the electrochemical stability of the cell was significantly degraded during long-term operation due to this delamination phenomenon.

[0092]

[0093] Figure 4 shows the results of measuring the air electrode-fuel electrode voltage (V1) and embedded probe-reference electrode voltage (V2) of a cell (LSM / YSZN cell) according to an embodiment applying an LSM anode and a YSZN electrolyte under the same conditions. As the current density increases, the oxygen partial pressure inside the electrolyte (probe location) is 6.438 x 10⁻⁶. -5 Although the pressure increased from atm to 0.21 atm, it maintained a much lower oxygen partial pressure compared to the YSZ electrolyte cell. This indicates that the oxygen partial pressure was effectively suppressed even under high current density conditions because the electron conductivity of the YSZN electrolyte is higher than that of the YSZ electrolyte. The initial OCV value was 0.9 V, which is about 0.1 V lower than that of YSZ, and the decrease in Faraday efficiency due to leakage current was minimal.

[0094]

[0095] FIG. 5 presents the results of measuring the air electrode-fuel electrode voltage (V1) and the embedded probe-reference electrode voltage (V2) while operating a cell (LSM / YSZN cell) according to an embodiment with an LSM anode and YSZN electrolyte for 50 hours continuously. The embedded probe-reference electrode voltage (V2) showed a relatively gradual change throughout the entire operation period. When converted to internal oxygen partial pressure according to the Nernst relationship, the internal oxygen partial pressure was consistently maintained in a lower range compared to a YSZ electrolyte cell under the same conditions, and in particular, the maximum value was also found to consistently fall below the peeling critical oxygen partial pressure (27,500 atm) of the YSZ electrolyte. This suppression of internal oxygen partial pressure alleviates the accumulation of oxygen gas at the electrolyte / air electrode interface and the resulting increase in local mechanical stress and reaction resistance, which is interpreted as the reason why the rate of increase in the air electrode-fuel electrode voltage (V1) was observed to be negligible. In other words, this demonstrates that the increased electron conductivity of the YSZN electrolyte maintained a low internal oxygen partial pressure even during long-term high-current operation, leading to improved electrochemical stability of the cell. However, post-hoc analysis confirmed that the La2Zr2O7 secondary phase formed by the chemical side reaction between LSM and YSZ caused delamination. To prevent delamination caused by such chemical factors and to clearly verify the net effect of the YSZN electrolyte's suppression of internal oxygen partial pressure contributing to cell stability, a cell with an LSCF anode interposed with a GDC buffer layer was additionally evaluated.

[0096]

[0097] FIG. 6 shows a current density of 0.6 A / cm² at OCV for a cell according to a comparative example (LSCF / YSZ cell) applying an LSCF anode and a YSZ electrolyte. 2The results are obtained by applying current up to the air electrode-fuel electrode voltage (V1) and the embedded probe-reference electrode voltage (V2). As the current density increased, the oxygen partial pressure inside the electrolyte (at the probe location) increased from 0.03 atm to 11.73 atm. This is a significantly lower value than when using an LSM anode (Figs. 2 and 3), indicating that the release of oxygen ions and interfacial reactions proceeded smoothly thanks to the fast ORR reaction rate and high electron conductivity of the LSCF.

[0098]

[0099] Figure 7 shows the results of measuring the air electrode-fuel electrode voltage (V1) and the embedded probe-reference electrode voltage (V2) while operating a cell (LSCF / YSZ cell) according to a comparative example with an LSCF anode and YSZ electrolyte for 50 hours. As operation continued, the embedded probe-reference electrode voltage (V2) was maintained stably within a constant range, and the converted internal oxygen partial pressure did not exceed the peeling critical oxygen partial pressure (27,500 atm) of the YSZ electrolyte. As a result, the air electrode-fuel electrode voltage (V1) also maintained an almost constant value without significant fluctuations or rapid increases. Therefore, it was verified that in the case of the cell with an LSCF anode and YSZ electrolyte, the stability of the electrolyte / air electrode interface is maintained even during long-term operation, and the electrochemical stability of the cell is not significantly degraded.

[0100]

[0101] FIG. 8 shows a battery (LSCF / YSZN cell) according to an embodiment applying an LSCF anode and a YSZN electrolyte, with a current density of 0.8 A / cm² at OCV. 2 This is the result of measuring the air electrode-fuel electrode voltage (V1) and the embedded probe-reference electrode voltage (V2) while applying up to. As the current density increases, the oxygen partial pressure inside the electrolyte is 1.02 x 10 -16 3.52 x 10 at the ATM-14 It increased slightly to atm. This indicates that not only was the internal oxygen partial pressure maintained much lower than that of the YSZ electrolyte cell under the same conditions, but the current density also increased compared to the maximum current density (0.6 A / cm²) applied to the YSZ electrolyte cell. 2 Current density higher than ) (0.8 A / cm² 2 Even though it was authorized up to ), it is still 10 -14 It shows that it maintained an extremely low value at the atm level.

[0102]

[0103] FIG. 9 shows a cell (LSCF / YSZN cell) according to an embodiment applying an LSCF anode and a YSZN electrolyte at 0.8 A / cm² for 50 hours. 2 This is the result of measuring the air electrode-fuel electrode voltage (V1) and the embedded probe-reference electrode voltage (V2) while operating for a long period under these conditions. The internal oxygen partial pressure calculated from the embedded probe-reference electrode voltage (V2) was significantly lower than the stripping critical oxygen partial pressure (27,500) of the YSZ electrolyte despite long-term operation, and was even 0.6 A / cm² 2 It maintained a lower value than the YSZ electrolyte cell operated under the conditions. As a result, the air electrode-fuel electrode voltage (V1) was also maintained stably without a significant increase during the operation period, and long-term operation stability was shown to be much better. This means that the YSZN electrolyte, which has improved N-type conductivity compared to YSZ, provides the effect of consistently lowering the internal oxygen partial pressure regardless of the air electrode material. In fact, in both cases where LSM and LSCF were applied as anodes, the YSZN electrolyte effectively suppressed the rise in internal oxygen partial pressure through the contribution of electron conduction even during long-term operation, and the decrease in Faraday efficiency due to leakage current was minimal. Therefore, it was verified that the solid oxide water electrolysis cell system based on the YSZN electrolyte can exhibit excellent performance in suppressing interfacial delamination and ensuring electrochemical stability.

[0104]

[0105] Although embodiments of the present invention have been described above with reference to the attached drawings, the present invention is not limited to the above embodiments and can be manufactured in various different forms, and those skilled in the art will understand that the present invention can be implemented in other specific forms without changing the technical concept or essential features of the present invention. Therefore, the embodiments described above should be understood as illustrative in all respects and not restrictive.

Claims

1. A solid oxide water electrolysis cell comprising a cathode layer, an electrolyte layer, and an anode layer, wherein The above electrolyte layer is, Characterized by comprising an electrolyte composed of yttria-stabilized zirconia (YSZ) and a solid solution (YSZN) containing ceria (CeO₂). Solid oxide water electrolysis cell.

2. In Paragraph 1, A solid oxide water electrolysis cell characterized by the solid solution comprising the above yttria-stabilized zirconia (YSZ) and ceria (CeO₂) being represented by the following chemical formula: Chemical formula xCeO2-(1-x)Y 0.08 Zr 0.92 O 2-d (0 < x ≤ 0.10).

3. In Paragraph 1, The above air electrode layer is, An air electrode functional layer comprising LSM (Sr-doped LaMnO3) or LSCF (Sr, Co-doped LaFeO3); and A solid oxide water electrolysis cell characterized by including an anode current collector (ACC) formed on the above air electrode functional layer.

4. In Paragraph 3, The above air electrode functional layer comprises LSM (Sr-doped LaMnO3) and YSZ, and A solid oxide water electrolysis cell characterized in that the air electrode current collector layer comprises LSM and carbon.

5. In Paragraph 3, The above air electrode functional layer comprises LSCF and GDC (Gd-doped CeO2), and The above air electrode current collector includes LSCF and carbon, and A solid oxide water electrolysis cell characterized by further including a buffer layer containing GDC between the air electrode layer and the electrolyte layer.

6. In Paragraph 1, The above fuel electrode layer is, Cathode Support (CS); and A solid oxide water electrolysis cell characterized by including a cathode functional layer (CFL) formed on the above-mentioned fuel electrode support layer.

7. In Paragraph 6, A solid oxide water electrolysis cell characterized in that the above-mentioned fuel electrode support layer and fuel electrode functional layer comprise NiO and YSZ.

8. A solid oxide water electrolysis cell stack comprising a plurality of solid oxide water electrolysis cell unit cells according to any one of claims 1 to 7.

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