A cathode material, its preparation method and application

Abstract

The present invention discloses a cathode material, a preparation method thereof and an application, belonging to the technical field of solid oxide fuel cells. The chemical formula of the cathode material is (Sr2Fe 1.5 Mo 0.38 P 0.12 O 6‑δ ) 0.9 [Sr3(PO4)2] 0.1 . The preparation method includes the following steps: S1: Weigh raw materials strontium nitrate, iron nitrate, ammonium molybdate, ammonium dihydrogen phosphate, glycine and citric acid; S2: Add deionized water to the raw materials, heat and stir to form a gel; S3: Treat the gel at 240-260 °C for 1.5-2.5 h to obtain a precursor; S4: Calcinate the precursor at 1000-1200 °C for 4-6 h to obtain the product. By introducing a proton-conducting phase into the electrode material through a simple and easy-to-operate self-assembly method, the electrochemical performance and stability of the electrode material are improved, and the problems of low electrochemical activity, cumbersome preparation process and poor stability of the cathode material of solid oxide fuel cells are solved.

Description

Technical Field

[0001] The present invention belongs to the technical field of solid oxide fuel cells, and particularly relates to a cathode material, a preparation method thereof and an application thereof. Background Art

[0002] Solid Oxide Fuel Cells (SOFC) are all-solid-state power generation devices that directly convert chemical energy into electrical energy, and have many advantages such as high energy conversion efficiency, strong fuel applicability, wide operating temperature range, and high mass energy density. However, the low electrochemical activity and stability of its cathode have become important factors restricting its long-term efficient operation and commercial promotion.

[0003] Currently, the cathodes of SOFC mainly use perovskite oxides such as La 0.8 Sr 0.2 Co 1-x Fe x O 3-δ (LSCF) and other perovskite oxides with mixed oxygen ion-electron conduction functions as electrocatalysts; however, the intrinsic proton conductivity of such perovskite materials is extremely small, resulting in the reaction active sites being mainly limited to the "air-cathode-electrolyte" triple-phase interface, thereby limiting the catalytic efficiency. The double perovskite oxide material Sr2Fe 1.5 Mo 0.5 O 6-δ (SFM) has good electrochemical activity and structural stability in air and is regarded as the most promising new SOFC electrode material. However, it is difficult to fully meet the actual requirements of SOFC under complex application conditions. The existing modification strategies for SFM mainly focus on the doping of metal ions. The doping strategy can improve its electrochemical activity to a certain extent, but due to the limitation of the intrinsic conductivity and problems such as lattice distortion caused by doping, it is impossible to obtain an SOFC electrode material with both excellent electrochemical activity and stability. Summary of the Invention

[0004] Aiming at the above-mentioned prior art, the present invention provides a cathode material, a preparation method thereof and an application thereof. By introducing a proton-conducting phase into the electrode material through a simple and easy-to-operate self-assembly method, the electrochemical performance and stability of the electrode material are improved, and the problems of low electrochemical activity, cumbersome preparation process and poor stability of the cathode material of solid oxide fuel cells are solved.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is: to provide a cathode material, and the chemical formula of the cathode material is (Sr2Fe 1.5 Mo 0.38 P 0.12 O 6-δ ) 0.9[Sr3(PO4)2] 0.1 。

[0006] The beneficial effects of the present invention adopting the above technical solutions are as follows: The material (Sr2Fe 1.5 Mo 0.38 P 0.12 O 6-δ ) 0.9 [Sr3(PO4)2] 0.1 , namely SFMP-SP, is composed of two phases of Sr2Fe 1.5 Mo 0.38 P 0.12 O 6-δ and Sr3(PO4)2. The Sr2Fe 1.5 Mo 0.38 P 0.12 O 6-δ phase plays a role in stabilizing the crystal structure and promoting electron transport, and the Sr3(PO4)2 phase significantly enhances the oxygen ion conduction ability of the material. The two work together to expand the reaction active sites from the "air-cathode-electrolyte" triple-phase interface to the entire electrode material, greatly improving the electrochemical activity. At the same time, Sr3(PO4)2 stably exists in the bulk phase of Sr2Fe 1.5 Mo 0.38 P 0.12 O 6-δ , and the two are closely combined, enhancing the stability of the electrode material.

[0007] Based on the above technical solutions, the present invention can also be improved as follows.

[0008] Further, the preparation method of the cathode material includes the following steps:

[0009] S1: Weigh raw materials strontium nitrate, iron nitrate, ammonium molybdate, ammonium dihydrogen phosphate, glycine and citric acid;

[0010] S2: Add deionized water to the raw materials, heat and stir at 75-85 °C to form a gel;

[0011] S3: Treat the gel at 240-260 °C for 1.5-2.5 h to obtain a precursor;

[0012] S4: Calcinate the precursor at 1000-1200 °C for 4-6 h to obtain the product.

[0013] The beneficial effects of the present invention adopting the above further technical solutions are as follows: By introducing a proton-conducting phase into the electrode material through a simple and easy-to-operate self-assembly method, the SFMP-SP material is prepared, improving the electrochemical activity and stability of the cathode material.

[0014] Further, the mass ratio of strontium nitrate, iron nitrate, ammonium molybdate, ammonium dihydrogen phosphate, glycine, and citric acid is 4.2326:6.06:0.7062:0.2306:10:10.

[0015] Further, the stirring temperature in S2 is 80 °C, and the stirring time is 12 h.

[0016] Further, the treatment temperature of the gel in S3 is 250 °C, and the treatment time is 2 h.

[0017] Further, the calcination temperature of the precursor in S4 is 1100 °C, and the calcination time is 5 h.

[0018] The beneficial effect of the present invention adopting the above further technical solution is that the cathode material SFMP-SP with high chemical activity and strong stability is prepared by a simple and easy-to-operate self-assembly method, which is convenient for the large-scale production and application promotion of SFMP-SP.

[0019] Further, the application of the cathode material in the preparation of solid oxide fuel cells.

[0020] The beneficial effect of the present invention adopting the above further technical solution is that the cathodes of existing solid oxide fuel cells generally have low electrochemical activity and stability, which are important factors restricting their long-term efficient operation and commercial promotion. Applying the SFMP-SP material can greatly improve the electrochemical activity of the cathodes of solid oxide fuel cells and enhance the stability of the electrodes.

[0021] Further, the solid oxide fuel cell has a flat tube structure.

[0022] The beneficial effect of the present invention adopting the above further technical solution is that the flat tube SOFC has advantages such as a larger specific catalytic activity area and stronger structural stability compared with SOFCs of other structures, and is considered to be the SOFC with the most potential for industrialization; applying this cathode material to the flat tube SOFC makes the SOFC have more excellent electrochemical activity and operating stability.

[0023] Further, using (Sr2Fe 1.5 Mo 0.38 P 0.12 O 6-δ ) 0.9 [Sr3(PO4)2] 0.1 as the cathode material, gadolinium-doped ceria as the electrolyte material, and nickel oxide and yttria-stabilized zirconia as the anode material, a fully high-entropy proton ceramic fuel cell NiO-YSZ||GDC||SFMP-SP is prepared.

[0024] Further, the fuel gas of the solid oxide fuel cell is hydrogen.

[0025] The beneficial effects of the present invention adopting the above further technical solutions are as follows: Gadolinium-doped ceria (GDC) has good ionic conductivity and lower operating temperature; the electrodes made of nickel oxide (NiO) and yttria-stabilized zirconia (YSZ) have excellent electrochemical activity; the finally fabricated flat-tubular SOFC has a high power output and can achieve stable output under long-term operation conditions.

[0026] The beneficial effects of the present invention are: The cathode material SFMP-SP has a biphasic structure with synergistic effects. The (Sr2Fe 1.5 Mo 0.38 P 0.12 O 6-δ ) 0.9 phase plays a role in stabilizing the crystal structure and promoting electron transport, and the Sr3(PO4)2 phase significantly enhances the oxygen ion conduction ability of the material. The synergistic effect of the two greatly improves the electrochemical activity of the material; at the same time, the two are closely combined, enhancing the stability of the electrode material. The cathode material SFMP-SP is prepared by a self-assembly method, and the process is simple, which is convenient for the large-scale production and application promotion of SFMP-SP. Making the cathode material SFMP-SP into the cathode of a flat-tubular SOFC solves the problem of low electrochemical activity of the SOFC cathode, and has the advantages of simple preparation method, high electrochemical activity, and high stability. The fabricated flat-tubular single cell NiO-YSZ||GDC||SFMP-SP achieves a high power output, and the maximum output power can reach 296 mW / cm 2 at the operating temperature of 750 °C, and can stably output at a constant current density of 150 mA / cm 2 for 50 h, that is, it shows stable output under long-term operating conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 is the X-ray diffraction characterization pattern of the cathode material (Sr2Fe 1.5 Mo 0.38 P 0.12 O 6-δ ) 0.9 [Sr3(PO4)2] 0.1 ;

[0028] Figure 2 is the external view of the flat-tubular single cell NiO-YSZ||GDC||SFMP-SP;

[0029] Figure 3 is the discharge I-V curve and I-P curve diagram of the flat-tubular single cell NiO-YSZ||GDC||SFMP-SP;

[0030] Figure 4It is the constant current discharge diagram of the flat tube single cell NiO-YSZ||GDC||SFMP-SP. Specific Embodiments

[0031] The following combines examples to make a detailed description of the specific embodiments of the present invention.

[0032] Example 1:

[0033] A cathode material with the chemical formula (Sr2Fe 1.5 Mo 0.38 P 0.12 O 6-δ ) 0.9 [Sr3(PO4)2] 0.1 , and the preparation method is as follows:

[0034] S1: Weigh 4.2326 g of strontium nitrate, 6.06 g of iron nitrate, 0.7062 g of ammonium molybdate, 0.2306 g of ammonium dihydrogen phosphate, 10 g of glycine, and 10 g of citric acid;

[0035] S2: Add 500 mL of deionized water to the weighed raw materials, heat in a water bath at 80 °C and stir for 12 h to obtain a gel;

[0036] S3: Treat the gel at 250 °C for 2 h to obtain a precursor;

[0037] S4: Calcinate the precursor at 1100 °C for 5 h to obtain (Sr2Fe 1.5 Mo 0.38 P 0.12 O 6-δ ) 0.9 [Sr3(PO4)2] 0.1 powder.

[0038] The (Sr2Fe 1.5 Mo 0.38 P 0.12 O 6-δ ) 0.9 [Sr3(PO4)2] 0.1 powder obtained in this example was analyzed by XRD, indicating that the material has a double-phase perovskite structure, as Figure 1 shown.

[0039] Example 2:

[0040] A cathode material with the chemical formula (Sr2Fe 1.5 Mo 0.38 P 0.12 O 6-δ ) 0.9 [Sr3(PO4)2] 0.1 , and the preparation method is as follows:

[0041] S1: Weigh 4.2326 g of strontium nitrate, 6.06 g of iron nitrate, 0.7062 g of ammonium molybdate, 0.2306 g of ammonium dihydrogen phosphate, 10 g of glycine and 10 g of citric acid;

[0042] S2: Add 500 mL of deionized water to the weighed raw materials, heat in a water bath at 75 °C and stir for 12 h to obtain a gel;

[0043] S3: Treat the gel at 240 °C for 2.5 h to obtain a precursor;

[0044] S4: Calcinate the precursor at 1000 °C for 6 h to obtain (Sr2Fe 1.5 Mo 0.38 P 0.12 O 6-δ ) 0.9 [Sr3(PO4)2] 0.1 powder.

[0045] The (Sr2Fe 1.5 Mo 0.38 P 0.12 O 6-δ ) 0.9 [Sr3(PO4)2] 0.1 powder obtained in this example shows a double-phase perovskite structure by XRD analysis.

[0046] Example 3:

[0047] A cathode material with the chemical formula (Sr2Fe 1.5 Mo 0.38 P 0.12 O 6-δ ) 0.9 [Sr3(PO4)2] 0.1 , and the preparation method is as follows:

[0048] S1: Weigh 4.2326 g of strontium nitrate, 6.06 g of iron nitrate, 0.7062 g of ammonium molybdate, 0.2306 g of ammonium dihydrogen phosphate, 10 g of glycine and 10 g of citric acid;

[0049] S2: Add 500 mL of deionized water to the weighed raw materials, heat in a water bath at 85 °C and stir for 12 h to obtain a gel;

[0050] S3: Treat the gel at 260 °C for 1.5 h to obtain a precursor;

[0051] S4: Calcinate the precursor at 1200 °C for 4 h to obtain (Sr2Fe 1.5 Mo 0.38 P 0.12 O 6-δ ) 0.9[Sr3(PO4)2] 0.1 Powder

[0052] The (Sr2Fe 1.5 Mo 0.38 P 0.12 O 6-δ ) 0.9 [Sr3(PO4)2] 0.1 powder obtained in this example shows that the material has a double-phase perovskite structure by XRD analysis.

[0053] Example 4:

[0054] A cathode material with the chemical formula (Sr2Fe 1.5 Mo 0.38 P 0.12 O 6-δ ) 0.9 [Sr3(PO4)2] 0.1 , and the preparation method is as follows:

[0055] S1: Weigh 8.4652 g of strontium nitrate, 12.12 g of iron nitrate, 1.4124 g of ammonium molybdate, 0.4612 g of ammonium dihydrogen phosphate, 20 g of glycine and 20 g of citric acid;

[0056] S2: Add 1000 mL of deionized water to the weighed raw materials, heat in a water bath at 80 °C and stir for 12 h to obtain a gel;

[0057] S3: Treat the gel at 250 °C for 2 h to obtain a precursor;

[0058] S4: Calcinate the precursor at 1100 °C for 5 h to obtain (Sr2Fe 1.5 Mo 0.38 P 0.12 O 6-δ ) 0.9 [Sr3(PO4)2] 0.1 powder.

[0059] The (Sr2Fe 1.5 Mo 0.38 P 0.12 O 6-δ ) 0.9 [Sr3(PO4)2] 0.1 powder obtained in this example shows that the material has a double-phase perovskite structure by XRD analysis.

[0060] Example 5:

[0061] A full high-entropy proton ceramic fuel cell NiO-YSZ||GDC||SFMP-SP, using (Sr2Fe 1.5 Mo 0.38 P0.12 O 6-δ ) 0.9 [Sr3(PO4)2] 0.1 The cathode material is gadolinium oxide doped cerium oxide as the electrolyte material, and nickel oxide and yttria stabilized zirconium oxide as the anode material. The preparation method is as follows:

[0062] (1) nickel oxide, yttria-stabilized zirconium oxide and soluble starch are uniformly mixed in a mass ratio of 6:4:2 to prepare an anode powder;

[0063] (2) the anode powder, deionized water and polyethylene glycol are fully stirred and mixed in a mass ratio of 0.76:0.2:0.04 to form a slurry, the slurry is extruded into a shape using a commercial extruder, and sintered at a high temperature of 1400° C. for 5 h to obtain a flat tube anode support;

[0064] (3) mixing gadolinium oxide-doped cerium oxide, polyethylene glycol, dibutyl phthalate and triethanolamine in a mass ratio of 1:0.2:0.15:0.15 to form an electrolyte slurry;

[0065] (4) using a commercial sprayer to evenly spray the electrolyte slurry onto a flat tube anode support, and sintering at 1400° C. for 8 h to obtain a NiO-YSZ||GDC half-cell;

[0066] (5) Cathode material SFMP-SP powder was prepared according to the method of Example 1. 0.1 g of cathode material, 0.008 g of ethyl cellulose, and 0.012 g of corn starch were placed in a volumetric flask, and 1.5 mL of terpineol was added to the volumetric flask. The mixture was stirred on a magnetic stirring table for 12 h to obtain a cathode slurry.

[0067] (6) The cathode slurry was screen-printed on a NiO-YSZ||GDC half-cell and calcined at 1100°C for 2 h to form a flat tubular SOFC single cell, namely NiO-YSZ||GDC||SFMP-SP, which is a full high-entropy proton ceramic fuel cell.

[0068] Flat tube single cell NiO-YSZ||GDC||SFMP-SP Figure 2 shown.

[0069] 50 mL / min hydrogen was introduced into the anode side as the carrier gas, static air was used as the oxidant, the operating temperature of the cell was 750 °C, and the maximum power output achieved was 296 mW / cm 2 The discharge IV curve and IP curve of the flat tube single cell NiO-YSZ||GDC||SFMP-SP are as follows: Figure 3 shown.

[0070] The flat-tube single cell NiO-YSZ||GDC||SFMP-SP outputs a constant current at a current density of 150 mA / cm² at the working temperature of 750 °C and operates stably for 50 h. Its constant-current discharge diagram is as shown in 2 . Figure 4

[0071] Although the specific embodiments of the present invention have been described in detail in conjunction with the embodiments, it should not be construed as a limitation on the protection scope of this patent. Within the scope described in the claims, various modifications and deformations that can be made by those skilled in the art without creative efforts still fall within the protection scope of this patent.​

Claims

1. A cathode material, characterized in that: The chemical formula of the cathode material is (Sr2Fe 1.5 Mo 0.38 P 0.12 O 6-δ ) 0.9 [Sr3(PO4)2] 0.1 ; The cathode material is prepared by the following steps: S1: weigh raw materials strontium nitrate, ferric nitrate, ammonium molybdate, diammonium phosphate, glycine and citric acid; S2: adding deionized water to the raw materials, heating and stirring at 75-85° C. to form a gel; S3: treating the gel at 240-260° C. for 1.5-2.5 h to obtain a precursor; S4: calcining the precursor at 1000-1200° C. for 4-6 hours to obtain the precursor.

2. The cathode material according to claim 1, characterized in that: The mass ratio of the strontium nitrate, ferric nitrate, ammonium molybdate, diammonium phosphate, glycine and citric acid is 4.2326:6.06:0.7062:0.2306:10:

10.

3. The cathode material according to claim 1, characterized in that: The stirring temperature in S2 is 80°C and the stirring time is 12h.

4. The cathode material according to claim 1, characterized in that: The treatment temperature of the gel in S3 is 250°C and the treatment time is 2h.

5. The cathode material according to claim 1, characterized in that: The precursor calcination temperature in S4 is 1100°C and the calcination time is 5h.

6. Use of the cathode material according to claim 1 in the preparation of solid oxide fuel cells.

7. The use according to claim 6, characterized in that: The solid oxide fuel cell is a flat tube structure.

8. The use according to claim 7, characterized in that: The (Sr2Fe 1.5 Mo 0.38 P 0.12 O 6-δ ) 0.9 [Sr3(PO4)2] 0.1 The full high entropy proton ceramic fuel cell NiO-YSZ||GDC||SFMP-SP was prepared by using gadolinium oxide-doped cerium oxide as the cathode material, nickel oxide and yttria-stabilized zirconia as the anode material.

9. The use according to claim 8, characterized in that: The fuel gas of the solid oxide fuel cell is hydrogen.

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