High-entropy perovskite type direct ammonia solid oxide fuel cell anode material as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of solid oxide fuel cells, and relates to a high-entropy perovskite type direct ammonia solid oxide fuel cell anode material as well as a preparation method and application thereof. The anode material is characterized in that the chemical formula of the anode material is SrTixTaxCoxZrxNbxO3-delta, x is equal to 0.2, delta is larger than or equal to 0 and smaller than or equal to 1, and delta is oxygen vacancy content. The high-entropy perovskite type direct ammonia solid oxide fuel cell anode material is synthesized by adopting carbonate and oxide as raw materials and utilizing a high-energy ball milling method through proper element doping and sintering temperature. The solid oxide fuel cell prepared from the material provided by the invention has good electrochemical performance and long-term stability in hydrogen and ammonia atmospheres. The material disclosed by the invention is simple to prepare and excellent in performance and has a very good application prospect.

Description

Technical Field

[0001] The present invention belongs to the technical field of solid oxide fuel cells, and relates to a high-entropy perovskite-type direct ammonia solid oxide fuel cell anode material, a preparation method thereof, and an application thereof. Background Art

[0002] Traditional fossil energy power generation will produce a large amount of greenhouse gases such as carbon dioxide, which has a serious impact on the environment. Finding clean and efficient energy conversion technologies has become an urgent task. Hydrogen energy is an ideal clean energy, and fuel cells are one of the best ways to efficiently convert hydrogen energy into electrical energy. As the most advanced, most efficient, and most difficult-to-develop fuel cell technology, solid oxide fuel cells (SOFCs) have the advantages of high conversion efficiency, low-carbon environmental protection, no use of precious metals, and flexible fuel types. Its energy conversion rate can reach 60%, and when used in combination with a cogeneration unit, the energy conversion efficiency can be as high as 85%. Deeply exploring and developing SOFC technology has far-reaching significance for building a sustainable energy system, coping with global environmental challenges, and promoting the green development of human society.

[0003] Hydrogen is the most widely used anode fuel gas, with high energy conversion efficiency and no pollution, but it has the disadvantages of being flammable, explosive, difficult to transport, and high preparation cost. Ammonia is extremely easy to compress, has a high hydrogen content (17.8 wt%), and has the advantages of being cheap, easy to obtain, easy to store, low pollution, and not flammable or explosive. It is a very promising hydrogen energy carrier. Therefore, it is very necessary to develop a direct ammonia solid oxide fuel cell anode material with high ammonia catalytic activity and high chemical stability. High-entropy oxides have good chemical stability, and there is a synergistic effect between multiple elements, which can effectively improve the catalytic activity of ammonia and is a good choice for direct ammonia solid oxide fuel cell anode materials. Therefore, the present invention has developed a high-entropy perovskite-type anode material, which has good ammonia catalytic activity, and a solid oxide fuel cell prepared with the material of the present invention has good performance under both hydrogen and ammonia. Summary of the Invention

[0004] One of the purposes of the present invention is to provide a solid oxide fuel cell anode material with high catalytic activity and stable performance under an ammonia fuel atmosphere.

[0005] Another purpose of the present invention is to provide a preparation method and an application of the above-mentioned high-entropy perovskite-type anode material.

[0006] To achieve the above purpose, the technical solution adopted by the present invention is as follows: A high-entropy perovskite-type direct ammonia solid oxide fuel cell anode material, characterized in that the molecular formula of the high-entropy perovskite-type direct ammonia solid oxide fuel cell anode material is SrTi x Ta x Co x Zrx Nb x O 3-δ , where x = 0.2, 0 ≤ δ ≤ 1, and δ is the oxygen vacancy content.

[0007] The present invention also provides a method for preparing the above-mentioned high-entropy perovskite-type direct ammonia solid oxide fuel cell anode material, which specifically includes the following steps: (1) According to the stoichiometric ratio of the metal elements in the chemical formula SrTi x Ta x Co x Zr x Nb x O 3-δ , weigh out the carbonates containing Sr 2 + , the oxides containing Ti 4+ , the oxides containing Co 3+ , the oxides containing Zr 4+ , the oxides containing Nb 5+ , the oxides containing Ta 5+ respectively; (2) Put the raw materials weighed in step (1) into a ball milling tank, add agate balls, and carry out ball milling; (3) Take out the slurry in step (2) from the ball milling tank, dry it, and collect the powder; (4) Put the powder in step (3) into a muffle furnace for pre-burning; (5) Put the powder pre-burned in step (4) into a mortar for grinding. After sufficient grinding, weigh out an appropriate amount of powder and press it into a tablet in a mold; (6) Put the tablet pressed in step (5) into a high-temperature furnace for calcination; (7) Put the sample tablet calcined in step (6) into a mortar, add an appropriate amount of absolute ethanol for grinding. After sufficient grinding, dry the sample to obtain the high-entropy perovskite-type direct ammonia solid oxide fuel cell anode electrode powder;

[0008] Preferably, the carbonate containing Sr 2+ in step (1) is SrCO3, the oxide containing Ti 4+ is TiO2, the oxide containing Co 3+ is Co3O4, the oxide containing Zr 4+ is ZrO2, the oxide containing Nb 5+ is Nb2O5, and the oxide containing Ta 5+ is Ta2O5;

[0009] Preferably, SrTi x Ta x Cox Zr x Nb x O 3-δ In the chemical formula, the molar ratio of Sr, Ti, Co, Zr, Nb, and Ta is 1:0.2:0.2:0.2:0.2:0.2.

[0010] Preferably, in step (2), the ball-to-powder ratio of the agate balls added to the ball mill to the sample is (9-11):1, and the ball milling time is 20-30 h.

[0011] Preferably, in step (4), the pre-sintering temperature is 900-1100 °C, and the pre-sintering time is 8-12 h.

[0012] Preferably, in step (5), the mass of the appropriate amount of powder is 0.3-1 g, the diameter of the tablet press mold is 10-15 mm, and the gauge pressure of the tablet press oil is 2-5 Mpa.

[0013] Preferably, in step (6), the calcination temperature is 1100-1300 °C, and the calcination time is 8-12 h.

[0014] Preferably, the chemical formula of a high-entropy perovskite-type direct ammonia solid oxide fuel cell anode material obtained by the above preparation method is SrTi 0.2 Co 0.2 Zr 0.2 Nb 0.2 Ta 0.2 O 3-δ , where δ is the oxygen vacancy concentration, and 0 ≤ δ ≤ 1.

[0015] The present invention also provides an application of a high-entropy perovskite-type direct ammonia solid oxide fuel cell anode material, which specifically includes the following steps: (1) Weigh an appropriate amount of the high-entropy perovskite-type direct ammonia solid oxide fuel cell anode electrode powder prepared above and place it in a mortar, add a certain amount of binder, and grind it evenly to make an anode electrode slurry; (2) Weigh an appropriate amount of cathode powder and place it in a mortar, add a certain amount of binder, and grind it evenly to make a cathode electrode slurry; (3) Coat the electrode slurries prepared in steps (1) and (2) evenly on both sides of the electrolyte, and dry them to obtain a full cell sheet; (4) Place the full cell sheet dried in step (3) in a high-temperature tube furnace, and calcine it at 900-1000 °C for 1-3 h in an N2 atmosphere to obtain a solid oxide fuel cell.

[0016] Preferably, in step (1), the mass ratio of the anode powder to the binder used is 1:(1.5-2.5); the binder used is prepared by mixing terpineol and ethyl cellulose in a mass ratio of 9:1.

[0017] Preferably, the cathode powder used in step (2) is SmBaCo2O 5+δ .

[0018] Preferably, the electrolyte in step (3) is La 0.9 Sr 0.1 Ga 0.8 Mg 0.2 O 2.85 , with a thickness of 0.3 mm.

[0019] Preferably, the calcination temperature in step (4) is 950 °C and the calcination time is 2 h.

[0020] The present invention provides a high-entropy perovskite-type direct ammonia solid oxide fuel cell anode material, its preparation method and application. Chemically, the chemical formula of the anode material is SrTi 0.2 Co 0.2 Zr 0.2 Nb 0.2 Ta 0.2 O 3-δ , which is a single perovskite structure. The compatibility test results show that the anode material has good chemical compatibility with the electrolyte material La 0.9 Sr 0.1 Ga 0.8 Mg 0.2 O 2.85 . The Ti-based perovskite material itself has good chemical stability and electronic conductivity, but the catalytic activity of this material for fuel gas is relatively insufficient. It is found that high-entropy doping at the B-site can improve the catalytic activity of the material for fuel gas. The present invention provides that Co, Zr, Nb, and Ta partially replace Ti at the B-site of the SrTiO 3-δ perovskite material, significantly improving the electrochemical performance of the SrTiO3-based anode material, and the solid oxide fuel cell prepared with this high-entropy material exhibits good ammonia catalytic performance.

[0021] The example results show that, using the high-entropy perovskite-type direct ammonia solid oxide fuel cell anode material provided by the present invention, through XRD characterization, no impurity peaks are generated in the product synthesized in air, showing a stable cubic phase structure; for the solid oxide fuel cell prepared with the high-entropy perovskite-type anode material provided by the present invention, at 850 °C in H2 atmosphere, the maximum output power is 540 mW cm -2 ; at 850 °C in NH3 atmosphere, the maximum output power is 395 mW cm -2 , which shows that this material has excellent electrochemical performance and good ammonia catalytic performance. Description of the Drawings

[0022] Figure 1XRD pattern of high-entropy perovskite SrTi synthesized in air 0.2 Co 0.2 Zr 0.2 Nb 0.2 Ta 0.2 O 3-δ and

[0023] Figure 2 Power density graph of a full cell made of the material SrTi of the present invention 0.2 Co 0.2 Zr 0.2 Nb 0.2 Ta 0.2 O 3-δ as the anode material under H2 atmosphere.

[0024] Figure 3 Power density graph of a full cell made of the material SrTi of the present invention 0.2 Co 0.2 Zr 0.2 Nb 0.2 Ta 0.2 O 3-δ as the anode material under NH3 atmosphere.

[0025] Figure 4 Long-term stability of a full cell made of the material SrTi of the present invention 0.2 Co 0.2 Zr 0.2 Nb 0.2 Ta 0.2 O 3-δ when operating under NH3 atmosphere Detailed implementation mode

[0026] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific implementation steps, but the present invention is not limited to the following examples.

[0027] The present invention provides a preparation method for an anode material of a high-entropy perovskite-type direct ammonia solid oxide fuel cell, which specifically includes the following steps: (1) Weigh the raw materials SrCO3, TiO2, Co3O4, ZrO2, Nb2O5, and Ta2O5 in a molar ratio of 1:0.2:0.067:0.2:0.1:0.1; (2) Put the medicines weighed in step (1) into a ball milling tank in sequence, add agate balls according to a ball-to-material ratio of 10:1, pour in an appropriate amount of alcohol and stir until uniform, and then put it into a ball mill for ball milling for 24 hours; (3) Take out the ball milling tank in step (2), use a dropper to extract the sample solution into a mortar, and then dry the solution in the mortar, and collect the obtained powder; (4)Collect the powder from step (3) into a crucible, place the crucible in a muffle furnace, and calcine it at 1000 °C for 10 h in an air atmosphere; (5)Put the powder calcined in step (4) into a mortar and grind it. After sufficient grinding, weigh 0.3 g of the powder and put it into a mold with a diameter of 13 mm, and press it into a tablet under a pressure of 4 MPa; (6)Put the tablet pressed in step (5) into a high-temperature furnace and calcine it at 1200 °C for 10 h in an air atmosphere; (7)Put the sample tablet calcined in step (6) into a mortar and grind it into powder, add an appropriate amount of absolute ethanol and grind it. After sufficient grinding, dry the sample with a baking lamp to obtain SrTi 0.2 Co 0.2 Zr 0.2 Nb 0.2 Ta 0.2 O 3-δ Solid oxide fuel cell anode electrode powder;

[0028] The present invention provides an application of a high-entropy perovskite-type direct ammonia solid oxide fuel cell anode material, which is characterized by specifically including the following steps: (1)Weigh an appropriate amount of the above-obtained SrTi 0.2 Co 0.2 Zr 0.2 Nb 0.2 Ta 0.2 O 3-δ Solid oxide fuel cell anode electrode powder into a mortar, add a certain amount of binder (the mass ratio of anode powder to binder is 1:1.5; the used binder is prepared by mixing terpineol and ethyl cellulose in a mass ratio of 9:1) and grind it evenly to make an anode electrode slurry; (2)Weigh an appropriate amount of SmBaCo2O 5+δ Cathode powder into a mortar, add a certain amount of binder, and grind it evenly to make a cathode electrode slurry (the SmBaCo2O 5+δ Cathode powder is prepared by solid-phase method and sintered at 1150 °C for 10 hours); (3)Use the screen printing method to evenly coat the electrode slurries prepared in steps (1) and (2) on both sides of a 0.3 mm electrolyte sheet La 0.9 Sr 0.1 Ga 0.8 Mg 0.2 O 2.85 , place it on an oven and dry it for 8 minutes to obtain a full cell sheet (the electrolyte sheet is sintered at 1400 °C for 10 h by dry pressing method to form a dense LSGM electrolyte sheet); (4) Place the fully dried battery chips from step (3) into a high-temperature tube furnace and calcine them at 950 °C for 2 hours under a N2 atmosphere to obtain a solid oxide fuel cell with SrTi 0.2 Co 0.2 Zr 0.2 Nb 0.2 Ta 0.2 O 3-δ material as the anode material; (5) After the single cell prepared in step (4) is collected by silver wires, it is sealed at one end of a ceramic tube with silver paste, with the cathode facing outwards, and fixed in a muffle furnace. The cathode and anode of the single cell are connected to an electrochemical workstation through silver wires. The fuel gas (H2 and NH3) is introduced into the anode of the solid oxide fuel cell through the ceramic tube, and the cathode of the solid oxide fuel cell is placed in the external air atmosphere. Direct current output to the outside is generated by the way of electrons being lost at the cathode and gained at the anode at high temperature, thereby realizing the conversion of chemical energy into electrical energy.

[0029] Use an X-ray diffractometer to perform a phase analysis on the powder of the SrTi 0.2 Co 0.2 Zr 0.2 Nb 0.2 Ta 0.2 O 3-δ anode material prepared in the present invention. As Figure 1 , it shows that the material in the present invention has a single structure during the synthesis process and no obvious impurity peaks.

[0030] Perform an electrochemical performance test on the solid oxide fuel cell full cell made of the material SrTi 0.2 Co 0.2 Zr 0.2 Nb 0.2 Ta 0.2 O 3-δ of the present invention as the anode material. The test results of the power density of the cell under H2 and NH3 are as Figure 2 , Figure 3 shown. Figure 2 It shows that the maximum output power of the material in the present invention at 850 °C in a H2 atmosphere is 540 mW cm -2 , and the maximum output power at 850 °C in an NH3 atmosphere is 395 mW cm -2 , which indicates that the material in the present invention has excellent electrochemical performance and good ammonia catalytic performance.

[0031] The above are only the preferred experimental cases of the present invention. All equivalent changes and modifications made according to the scope of the patent application of the present invention shall fall within the scope covered by the present invention.

Claims

1. A method for preparing a high entropy perovskite type direct ammonia solid oxide fuel cell anode material, characterized in that: Its chemical formula is SrTi x Ta x Co x Zr x Nb x O 3-δ , wherein x=0.2, 0≤δ≤1, δ is the oxygen vacancy content; the preparation method adopts the following steps: (1) According to the chemical formula SrTi x Ta x Co x Zr x Nb x O 3-δ The stoichiometric ratio of the metal elements in the 2+ Carbonate containing Ti 4+ Oxide, containing Co 3+ Oxide containing Zr 4+ Oxide, containing Nb 5+ Oxide, containing Ta 5 + Oxides; (2) placing the raw materials weighed in step (1) into a ball mill, adding agate balls and an appropriate amount of ethanol, and ball milling; (3) taking the slurry in step (2) out of the ball mill, drying it, and collecting it to obtain a powder; (4) placing the powder from step (3) into a muffle furnace for pre-calcination; (5) grinding the powder pre-sintered in step (4) in a mortar. After sufficient grinding, weigh an appropriate amount of the powder and put it into a mold to press into tablets. (6) placing the pressed tablets in step (5) into a high temperature furnace for calcining; (7) The sample piece calcined in step (6) is placed in a mortar, and an appropriate amount of anhydrous ethanol is added for grinding. After sufficient grinding, the sample is dried to obtain a high entropy perovskite-type direct ammonia solid oxide fuel cell anode powder.

2. The preparation method according to claim 1, characterized in that: Step (1) contains Sr 2+ The carbonate is SrCO3, containing Ti 4+ The oxide is TiO2, containing Co 3+ The oxide is Co3O4, containing Zr 4+ The oxide is ZrO2, containing Nb 5+ The oxide is Nb2O5, containing Ta 5+ The oxide is Ta2O5; the SrTi x Ta x Co x Zr x Nb x O 3-δ The molar ratio of Sr, Ti, Co, Zr, Nb and Ta in the chemical formula is 1:0.2:0.2:0.2:0.2:0.

2.

3. The preparation method according to claim 1, characterized in that: In step (2), the ratio of agate balls added to the ball mill to the sample is (9-11):1, and the ball milling time is 20-30 hours.

4. The preparation method according to claim 1, characterized in that: In step (4), the pre-firing temperature is 900-1100° C. and the pre-firing time is 8-12 hours.

5. The preparation method according to claim 1, characterized in that: The mass of the appropriate amount of powder in step (5) is 0.3-1 g, the diameter of the tablet pressing mold is 10-15 mm, and the oil gauge pressure of the tablet pressing machine is 2-5 MPa.

6. The preparation method according to claim 1, characterized in that: In step (6), the calcination temperature is 1100-1300° C. and the calcination time is 8-12 hours.

7. Application of the high entropy perovskite solid oxide fuel cell anode material prepared by the method according to claims 1-6, characterized in that: The high entropy perovskite solid oxide fuel cell anode material is used to prepare the anode in a solid oxide fuel cell.

8. The use according to claim 7, characterized in that: The solid oxide fuel cell is prepared by the following steps: (1) Weigh an appropriate amount of the high entropy perovskite SrTi prepared above 0.2 Ta 0.2 Co 0.2 Zr 0.2 Nb 0.2 O 3-δ The anode electrode powder is placed in a mortar, and an appropriate amount of a binder (composed of pine alcohol and ethyl cellulose in a mass ratio of 9:1) is added and ground to obtain a battery anode slurry, wherein the mass ratio of the anode powder to the binder is 1:(1.5-2.5); (2) Weigh a certain amount of SmBaCo2O 5+δ The cathode powder is placed in a mortar, and an appropriate amount of a binder (composed of pine alcohol and ethyl cellulose in a mass ratio of 9:1) is added and ground to obtain a battery cathode slurry, wherein the mass ratio of the cathode powder to the binder is 1:(1.5-2.5); (3) The electrode slurry prepared in the above steps (1) and (2) is evenly coated on the electrolyte sheet La by screen printing. 0.9 Sr 0.1 Ga 0.8 Mg 0.2 O 2.85 Both sides of the battery are dried with a baking lamp to obtain a complete battery cell; (4) placing the full cell obtained in step (3) in a high temperature tube furnace and calcining at 900-1100° C. for 2-4 h under N2 to obtain SrTi 0.2 Ta 0.2 Co 0.2 Zr 0.2 Nb 0.2 O 3-δ Solid oxide fuel cell with anode material.

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