Composite electrolyte buffer layer for solid oxide electrolysis cell and method of making

Abstract

The application discloses a composite electrolyte buffer layer for solid oxide electrolysis cell and a preparation method, and relates to the technical field of SOFC electrolyte. The composite electrolyte buffer layer is formed by sequentially sputtering electrolyte sputtering dense layer I, electrolyte sputtering dense layer II and anode sputtering layer on the surface of the electrolyte layer of the solid oxide electrolysis cell. The thickness of the electrolyte sputtering dense layer I is 10 nanometers to 1 micrometer, the thickness of the electrolyte sputtering dense layer II is 50 nanometers to 500 nanometers, and the thickness of the anode sputtering layer is 5 nanometers to 30 nanometers. The composite electrolyte nanometer buffer layer prepared by the magnetron sputtering method has the advantages of blocking electrons, improving open circuit voltage, enhancing ion conductivity to reduce ohmic resistance, enhancing chemical compatibility and thermal matching with electrodes to improve long-term stability, etc. The composite electrolyte nanometer buffer layer solves the problem of internal leakage of the traditional low-temperature electrolyte, improves the open circuit voltage to above 1.00V (600 DEG C), improves the output power and stability of the solid oxide electrolysis cell, and expands the application range of the solid oxide electrolysis cell.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of solid oxide fuel cell electrolyte, in particular to a composite electrolyte buffer layer for solid oxide electrolysis cell and a preparation method thereof. BACKGROUND

[0002] Traditional solid oxide fuel cells use zirconia-based oxides as electrolytes, which can meet the performance and stability requirements at high operating temperatures (800-1000℃), but at medium and low temperatures, the relatively low ionic conductivity and excessive ohmic resistance result in more performance loss; in addition, the zirconia-based electrolyte is prone to react with the electrode material to form a high-resistance phase, which causes stability problems during long-term operation.

[0003] Cerium-based electrolytes have high ionic conductivity and are extremely potential medium and low temperature solid oxide fuel cell electrolytes, but their electronic conductivity can cause serious internal leakage, resulting in low open-circuit voltage and serious internal consumption of the battery, which makes it difficult to apply to electrolysis cells. To solve the internal leakage problem of cerium-based electrolytes, on the one hand, new components of electrolytes are developed, and by doping oxides in fluorite phase or designing new phase structures, the internal electronic conductivity is reduced, but in the actual test of redox atmosphere, the cerium-based electrolyte still has long-term stability problems. On the other hand, by increasing the barrier layer to improve the internal leakage problem, such as adding a YSZ layer on the surface of GDC, the internal leakage problem can be alleviated; but some commonly used electrode catalyst materials, such as lanthanum-based perovskite oxide electrodes, will react with YSZ at the interface during long-term operation, forming a lanthanum zirconate barrier phase and causing performance degradation. Further, by sputtering GDC on the surface of the YSZ barrier layer, the harmful interface reaction caused by chemical compatibility can be alleviated, but the thermal expansion coefficient of GDC (~12×10 -6 K -1 ) does not match the thermal expansion coefficient of some commonly used high-performance cathode materials, such as barium-cobalt-based perovskite oxides (>20×10 -6 K -1 ), which causes the electrode to fall off from the surface of the electrolyte during preparation and testing, resulting in large interface resistance and other problems.

[0004] In summary, there is an urgent need to design a method for improving the internal leakage and stability of medium and low temperature high performance cerium-based electrolytes for solid oxide electrolysis cells. SUMMARY

[0005] To solve the above technical problems, the application discloses a composite electrolyte buffer layer for solid oxide electrolysis cells and a preparation method.

[0006] The composite electrolyte buffer layer for solid oxide electrolysis cells can break through the traditional internal leakage of low-temperature electrolyte, increase the open circuit voltage to above 1.00V (600 DEG C), and greatly enhance the chemical compatibility and thermal matching with electrodes, thereby effectively improving the long-term stability of solid oxide electrolysis cells and promoting the development and application of the solid oxide electrolysis cells.

[0007] To achieve the above object, the application adopts the following technical scheme:

[0008] A composite electrolyte buffer layer for solid oxide electrolysis cells comprises electrolyte sputtering dense layer I, electrolyte sputtering dense layer II and anode sputtering layer which are sputtered on the surface of the electrolyte layer of the solid oxide electrolysis cell in sequence.

[0009] Among them:

[0010] The electrolyte sputtering dense layer I has a thickness of 10nm-1um and is used for ion conduction, electron insulation and open circuit voltage increase.

[0011] The electrolyte sputtering dense layer II has a thickness of 50nm-500nm and is used for increasing electrolyte conductivity and improving the chemical compatibility of the electrolyte and the anode interface.

[0012] The anode sputtering layer has a thickness of 5nm-30nm and is used for electron conduction, improvement of the thermal matching of the electrolyte and the anode and interface connectivity.

[0013] Further, the electrolyte sputtering dense layer I is composed of one of scandium oxide stabilized zirconia (ScSZ), yttrium oxide stabilized zirconia (YSZ), cerium oxide doped zirconia (CCZ) and yttrium doped barium zirconate (BZY).

[0014] Further, the electrolyte sputtering dense layer II is composed of one of gadolinium oxide doped cerium oxide (GDC), samarium oxide doped cerium oxide (SDC) and yttrium doped barium cerate (BCY).

[0015] Further, the anode sputtering layer is composed of one of barium cobaltate (BC), barium ferrite (BF) and iron doped barium cobaltate oxide (BCF).

[0016] The application also discloses a preparation method of the composite electrolyte buffer layer for the solid oxide electrolysis cell.

[0017] Further, the process of sputtering the electrolyte sputtering dense layer I is as follows:

[0018] The alloy target material is one of scandium-zirconium alloy, yttrium-zirconium alloy, cerium-zirconium alloy and yttrium-zirconium-barium alloy, the sputtering temperature is 300-600 DEG C, the sputtering power is 90-180 W, the sputtering time is 30-800 minutes, the sputtering atmosphere is a mixed gas of argon and oxygen, the argon flow is 1-10 sccm, the oxygen flow is 0.1-5 sccm, after sputtering, annealing is carried out at 800 DEG C-950 DEG C for 1-10 hours, and the sputtering process can be repeated 1-3 times.

[0019] Further, the process of sputtering the electrolyte sputtering dense layer II is as follows:

[0020] The alloy target material is one of gadolinium-cerium alloy, samarium-cerium alloy and yttrium-cerium-barium alloy, the sputtering temperature is 100-350 DEG C, the sputtering power is 100-180 W, the sputtering time is 30-120 minutes, the sputtering atmosphere is a mixed gas of argon and oxygen, the argon flow is 1-10 sccm, the oxygen flow is 0.1-5 sccm, after sputtering, annealing is carried out at 900 DEG C-950 DEG C for 1-10 hours, and the sputtering process can be repeated 1-3 times.

[0021] Further, the process of sputtering the anode sputtering layer is as follows:

[0022] The alloy target material is one of cobalt-barium alloy, iron-barium alloy and iron-cobalt-barium alloy, the sputtering temperature is 10-300 DEG C, the sputtering power is 50-120 W, the sputtering time is 5-30 minutes, the sputtering atmosphere is a mixed gas of argon and oxygen, the argon flow is 1-10 sccm, the oxygen flow is 0.1-5 sccm, after sputtering, annealing is carried out at 300 DEG C-800 DEG C for 0.5-5 hours.

[0023] The application has the advantages that, compared with the prior art,

[0024] The application adopts the physical vapor deposition method to prepare the electrolyte sputtering dense layer I on the surface of the cerium-based electrolyte micron layer, the nanometer diaphragm can effectively block the internal electronic conduction problem, the nanometer film layer and the interface formed at the same time also form high ion conductivity, which can improve the internal leakage and increase the open circuit voltage, and also can enhance the ion conductivity, so that the purpose of reducing the ohmic loss is achieved.

[0025] The electrolyte sputtering dense layer II is further prepared on the surface of the electrolyte separator, and is used as a nanometer buffer layer of the electrode, which has high compatibility and matching with the substrate film, and has high ion conductivity.

[0026] The component of the anode nanometer buffer layer prepared on the electrolyte sputtering dense layer II is close to the electrode material, and has high compatibility and matching with the electrode layer in the preparation and testing process. In addition, the nanometer structure of the electrode nanometer buffer layer helps to improve the internal ion and electron conductivity, and forms certain catalytic active sites on the surface, so that the electrode activity can be greatly improved.

[0027] The composite electrolyte buffer layer prepared by the application is suitable for both oxygen ion type solid oxide electrolysis cells and proton type solid oxide electrolysis cells, and the high-performance cell system at medium and low temperatures is applied to the high-efficiency electrolysis system by improving and optimizing the structure of the electrolyte layer.

[0028] The method can realize the application of the high-performance solid oxide cell with cerium-based fluorite phase or perovskite phase oxide as the electrolyte in the electrolysis field. The composite electrolyte nanometer buffer layer is prepared by the magnetron sputtering method, has the advantages of blocking electrons to improve the open circuit voltage, enhancing ion conductivity to reduce the ohmic resistance, enhancing the chemical compatibility and thermal matching with the electrode to improve the long-term stability, and the like, and is conducive to promoting the development and application of the high-performance solid oxide electrolysis cell in the electrolysis field. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 The structure diagram of the cross section (top) and the surface (bottom) of the YSZ buffer layer prepared in example 1 of the application is shown in the figure;

[0030] Figure 2 The structure diagram of the cross section (top) and the surface (bottom) of the YSZ and GDC double buffer layer prepared in example 1 of the application is shown in the figure;

[0031] Figure 3 The I-V curve of the cell prepared in example 1 of the application is shown in the figure;

[0032] Figure 4 The stability test of the cell prepared in example 1 of the application is shown in the figure;

[0033] Figure 5 The structure diagram of the cross section (top) and the surface (bottom) of the YSZ buffer layer prepared in example 2 of the application is shown in the figure. DETAILED DESCRIPTION

[0034] In order to make the purposes, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort belong to the protection scope of the present application.

[0035] Embodiment 1

[0036] A preparation method of a composite electrolyte buffer layer for a solid oxide electrolysis cell, which comprises the following steps: sequentially sputtering electrolyte sputtering dense layer I, electrolyte sputtering dense layer II and anode sputtering layer on the surface of the electrolyte layer of the solid oxide electrolysis cell by using a magnetron sputtering method. The specific process is as follows:

[0037] The electrolyte sputtering dense layer I is prepared by using a magnetron sputtering method, and the composition is yttrium-stabilized zirconia (YSZ). A yttrium-zirconium alloy target material is used, the sputtering temperature is 500 DEG C, the sputtering power is 180 W, the sputtering time is 35 minutes, the sputtering atmosphere is a mixed gas of argon and oxygen, the argon flow rate is 10 sccm, the oxygen flow rate is 5 sccm, and the sputtering is followed by annealing at 900 DEG C for 2 hours. As shown in FIG. 1, a surface-dense electron-blocking buffer layer is obtained, and the thickness is 60-70 nanometers. Figure 1

[0038] The electrolyte dense layer II is continuously prepared by using a magnetron sputtering method, and the composition is gadolinium-doped ceria (GDC). A gadolinium-cerium alloy target material is used, the sputtering temperature is 300 DEG C, the sputtering power is 90 W, the sputtering time is 50 minutes, the sputtering atmosphere is a mixed gas of argon and oxygen, the argon flow rate is 10 sccm, the oxygen flow rate is 5 sccm, and the sputtering is followed by annealing at 900 DEG C for 2 hours. As shown in FIG. 2, a surface-dense compatibility buffer layer is obtained, and the thickness is 70-80 nanometers. Figure 2

[0039] The anode sputtering layer is prepared by using a magnetron sputtering method, and the composition is barium cobaltate (BC). A specific cobalt-barium alloy target material is used, the sputtering temperature is 300 DEG C, the sputtering power is 120 W, the sputtering time is 5 minutes, the sputtering atmosphere is a mixed gas of argon and oxygen, the argon flow rate is 10 sccm, the oxygen flow rate is 5 sccm, and the sputtering is followed by annealing at 800 DEG C for 2 hours. A thermal matching buffer layer is obtained, and the thickness is 5-10 nanometers. The composite electrolyte buffer layer is prepared.

[0040] The prepared composite electrolyte buffer layer is assembled into a battery for performance testing. As shown in FIG. 3 and FIG. 4, the open-circuit voltage reaches 1.086 V at 600 DEG C, and the electrolysis current reaches 1.5 A cm. Figure 3 Figure 4 and​​​-2 The above and the electrolysis stability can be improved.

[0041] Example 2

[0042] A preparation method of a composite electrolyte buffer layer for a solid oxide electrolysis cell, which comprises: sequentially sputtering an electrolyte sputtering dense layer I, an electrolyte sputtering dense layer II and an anode sputtering layer on the surface of an electrolyte layer of the solid oxide electrolysis cell by using a magnetron sputtering method. Specifically,

[0043] The electrolyte sputtering dense layer I is prepared by using a magnetron sputtering method, and the composition is yttrium-stabilized zirconia (YSZ), a yttrium-zirconium alloy target material is used, the sputtering temperature is 400 DEG C, the sputtering power is 120 W, the sputtering time is 770 minutes, the sputtering atmosphere is a mixed gas of argon and oxygen, the argon flow rate is 10 sccm, the oxygen flow rate is 5 sccm, and the sputtering is followed by annealing at 900 DEG C for 2 hours; as shown in the figure, a surface dense electron-blocking buffer layer is obtained, and the thickness is 600-650 nanometers. Figure 5

[0044] The electrolyte dense layer II is prepared by using a magnetron sputtering method, and the composition is gadolinium-doped ceria (GDC), a gadolinium-cerium alloy target material is used, the sputtering temperature is 300 DEG C, the sputtering power is 120 W, the sputtering time is 50 minutes, the sputtering atmosphere is a mixed gas of argon and oxygen, the argon flow rate is 10 sccm, the oxygen flow rate is 1 sccm, and the sputtering is followed by annealing at 950 DEG C for 2 hours, so as to obtain a surface dense compatibility buffer layer, and the thickness is 120-150 nanometers.

[0045] The anode sputtering layer is prepared by using a magnetron sputtering method, and the composition is barium cobaltate (BC), a specific cobalt-barium alloy target material is used, the sputtering temperature is 300 DEG C, the sputtering power is 120 W, the sputtering time is 5 minutes, the sputtering atmosphere is a mixed gas of argon and oxygen, the argon flow rate is 10 sccm, the oxygen flow rate is 1 sccm, and the sputtering is followed by annealing at 800 DEG C for 2 hours, so as to obtain a thermal matching buffer layer, and the thickness is 5-10 nanometers; and a composite electrolyte buffer layer is prepared.

[0046] The prepared composite electrolyte buffer layer is assembled into a cell for performance testing, the open-circuit voltage reaches 1.035 V at 650 DEG C, and the electrolysis current reaches 2.5 A cm -2 The above and the electrolysis stability can be improved.

[0047] Example 3

[0048] A preparation method of a composite electrolyte buffer layer for a solid oxide electrolysis cell, which comprises: sequentially sputtering an electrolyte sputtering dense layer I, an electrolyte sputtering dense layer II and an anode sputtering layer on the surface of an electrolyte layer of the solid oxide electrolysis cell by using a magnetron sputtering method. Specifically, ​

[0049] The electrolyte sputtering dense layer I is prepared by magnetron sputtering method, and the composition is scandium oxide stabilized zirconia (SSZ), the scandium-zirconium alloy target is used, the sputtering temperature is 500°C, the sputtering power is 120W, the sputtering time is 35 minutes, the sputtering atmosphere is argon and oxygen mixed gas, wherein the argon flow is 10sccm, the oxygen flow is 5sccm, after sputtering, annealing at 900°C for 2h, a surface dense electron blocking layer is obtained, and the thickness is 50-60nm.

[0050] The electrolyte dense layer II is continuously prepared by magnetron sputtering method, and the composition is gadolinium oxide doped cerium oxide (GDC), the gadolinium-cerium alloy target is used, the sputtering temperature is 300°C, the sputtering power is 180W, the sputtering time is 50 minutes, the sputtering atmosphere is argon and oxygen mixed gas, wherein the argon flow is 10sccm, the oxygen flow is 1sccm, after sputtering, annealing at 950°C for 2h, a surface dense compatibility buffer layer is obtained, and the thickness is 280-300nm.

[0051] The anode sputtering layer is prepared by magnetron sputtering method, and the composition is barium cobaltate (BC), the special cobalt-barium alloy target is used, the sputtering temperature is 300°C, the sputtering power is 120W, the sputtering time is 5 minutes, the sputtering atmosphere is argon and oxygen mixed gas, wherein the argon flow is 10sccm, the oxygen flow is 1sccm, after sputtering, annealing at 900°C for 2h, a thermal matching buffer layer is obtained, and the thickness is 5-10nm; and the composite electrolyte buffer layer is prepared.

[0052] The prepared composite electrolyte buffer layer is assembled into a battery for performance test, and the open circuit voltage reaches 1.05V at 600°C, and the electrolysis current reaches 1.5A cm -2 The above, and the electrolytic stability is improved.

[0053] Of course, the above description is not a limitation of the present application, and the present application is not limited to the above examples, and the changes, modifications, additions or replacements made by the person skilled in the art within the essential scope of the present application should also belong to the protection scope of the present application.

Claims

1. A composite electrolyte buffer layer for solid oxide electrolysis cells, characterized in that, The surface of the solid oxide electrolysis cell electrolyte layer is sputtered with electrolyte sputtering dense layer I, electrolyte sputtering dense layer II and anode sputtering layer in sequence; Wherein: The electrolyte sputtering dense layer I has a thickness of 10 nm to 1 micron, and is used for ion conduction, electron insulation and open circuit voltage improvement; The electrolyte sputtering dense layer II has a thickness of 50 nm to 500 nm, and is used for increasing electrolyte conductivity and improving electrolyte and anode interface chemical compatibility; The anode sputtering layer has a thickness of 5 nm to 30 nm, and is used for electron conduction, electrolyte and anode thermal matching and interface connection improvement; The electrolyte sputtering dense layer I is composed of one of scandium oxide stabilized zirconia, yttrium oxide stabilized zirconia, cerium doped zirconia and yttrium doped barium zirconate; The electrolyte sputtering dense layer II is composed of one of gadolinium oxide doped cerium oxide, samarium oxide doped cerium oxide and yttrium doped barium cerate; The anode sputtering layer is composed of one of barium cobaltate, barium ferrite and iron doped barium cobaltate.

2. The method for preparing a composite electrolyte buffer layer for a solid oxide electrolysis cell according to claim 1, characterized by, The surface of the solid oxide electrolysis cell electrolyte layer is sputtered with electrolyte sputtering dense layer I, electrolyte sputtering dense layer II and anode sputtering layer in sequence by using a magnetron sputtering method to form a composite electrolyte buffer layer.

3. The method for preparing a composite electrolyte buffer layer for a solid oxide electrolysis cell according to claim 2, characterized by, The process of sputtering the electrolyte sputtering dense layer I is as follows: The alloy target material is one of scandium-zirconium alloy, yttrium-zirconium alloy, cerium-zirconium alloy and yttrium-zirconium-barium alloy, the sputtering temperature is 300-600 ℃, the sputtering power is 90-180 W, the sputtering time is 30-800 minutes, the sputtering atmosphere is a mixture of argon and oxygen, the argon flow rate is 1-10 sccm, the oxygen flow rate is 0.1-5 sccm, the sputtering is followed by annealing at 800 ℃-950 ℃ for 1-10 hours, and the sputtering process is repeated 1-3 times.

4. The method for preparing a composite electrolyte buffer layer for a solid oxide electrolysis cell according to claim 3, characterized by, The process of sputtering the electrolyte sputtering dense layer II is as follows: The alloy target material is one of gadolinium-cerium alloy, samarium-cerium alloy and yttrium-cerium-barium alloy, the sputtering temperature is 100-350 ℃, the sputtering power is 100-180 W, the sputtering time is 30-120 minutes, the sputtering atmosphere is a mixture of argon and oxygen, the argon flow rate is 1-10 sccm, the oxygen flow rate is 0.1-5 sccm, the sputtering is followed by annealing at 900 ℃-950 ℃ for 1-10 hours, and the sputtering process is repeated 1-3 times.

5. The method for preparing a composite electrolyte buffer layer for a solid oxide electrolysis cell according to claim 4, characterized by, The process of sputtering the anode sputtering layer is as follows: The alloy target material is one of cobalt-barium alloy, iron-barium alloy and iron-cobalt-barium alloy, the sputtering temperature is 10-300 ℃, the sputtering power is 50-120 W, the sputtering time is 5-30 minutes, the sputtering atmosphere is a mixture of argon and oxygen, the argon flow rate is 1-10 sccm, the oxygen flow rate is 0.1-5 sccm, the sputtering is followed by annealing at 300 ℃-800 ℃ for 0.5-5 hours.

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