Preparation method of SOFC cathode material and connector coating material

Abstract

The invention discloses a preparation method of an SOFC (solid oxide fuel cell) cathode material and a connector coating material, and relates to the technical field of solid oxide fuel cells, an aqueous solution of a coprecipitant is adopted to replace pure water to wash a precursor, acid radical ions brought in by metal salt can be removed, dissolution and precipitation of a lanthanum source precursor can be inhibited, and the performance of the precursor is improved. The growth of lanthanum source precursor particles is avoided, and the problem that the precursor cannot be completely subjected to phase formation during high-temperature calcination due to the growth of the lanthanum source precursor particles when the precursor is washed by pure water is solved.

Description

Technical Field

[0001] The invention relates to the technical field of solid oxide fuel cells, and in particular to a method for preparing a SOFC cathode material and a connector coating material. Background Art

[0002] Solid oxide fuel cell (SOFC) is the third generation fuel cell after phosphate fuel cell and molten carbonate fuel cell. It is an efficient and environmentally friendly energy conversion device. SOFC can directly convert the energy in fossil energy into electrical energy without being limited by the Carnot cycle. With the increasing severity of energy and environmental problems, the research on SOFC has become a hot spot in the field of energy and materials.

[0003] Perovskite originally referred to an inorganic mineral in the form of CaTiO3, and later became a synonym for a compound with the chemical formula ABO3 and the same crystal structure type as CaTiO3. 1-x A′B 1-y B y 'O3 and other compounds. The crystal structure of this type of compound has not changed fundamentally, but has caused changes in the defect structure. At present, perovskite oxides have been widely used as magnetic materials, superconducting materials, fuel cell cathode materials, fuel cell connector materials, catalytic materials, etc.

[0004] Currently, the commonly used SOFC cathode material is La 1-x Sr x Co 1-y Fe y O 3-δ (LSCF) and La 1-x Sr x MnO 3-δ (LSM), etc., the coating material of the connector is La 1-x Sr x MnO 3-δ (LSM) and La 1-x Sr x CoO 3-δ (LSC), etc. When these materials are prepared by coprecipitation, the La source precursor in the precursor slurry obtained after coprecipitation will gradually grow from nanoparticles to large particles during the washing process, resulting in incomplete reaction of the material precursor when calcining into phases. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a method for preparing SOFC cathode material and connector coating material, which can effectively solve the problem of incomplete reaction when the precursor is calcined into phases during the preparation of SOFC cathode material and connector coating material by co-precipitation method.

[0006] The technical problem to be solved by the present invention is achieved by adopting the following technical solutions:

[0007] A method for preparing a SOFC cathode material and a connector coating material comprises the following steps:

[0008] (1) dissolving a metal salt in water to obtain a solution 1;

[0009] (2) dissolving the coprecipitant in water to obtain solution 2;

[0010] (3) reacting solution 1 with solution 2 to obtain a precursor slurry;

[0011] (4) filtering the precursor slurry, washing the filter residue with the diluted solution 2, and drying to obtain a precursor;

[0012] (5) calcining the precursor at high temperature to obtain SOFC cathode material or interconnect coating material.

[0013] Further, the metal salt includes a water-soluble salt of a lanthanide metal, strontium, and at least one metal selected from manganese, cobalt, iron, nickel, bismuth, barium, etc., that is, the metal salt includes a water-soluble salt of a lanthanide metal, a water-soluble salt of strontium, and at least one metal selected from manganese, cobalt, iron, nickel, bismuth, and barium. In the present invention, the use of a water-soluble salt as a metal source is conducive to using water as a solvent, which can improve the environmental friendliness of the process and reduce the preparation cost.

[0014] Furthermore, the water-soluble salt is at least one of nitrate, chloride, sulfate, and acetate, but is not limited thereto.

[0015] Further, the coprecipitant is ammonium carbonate. In the present invention, ammonium carbonate is used as a coprecipitant, not only can the target precursor be prepared, but also the diluted ammonium carbonate aqueous solution can be used to wash the precursor, inhibiting the dissolution and precipitation of the lanthanum source precursor (lanthanum is precipitated in the form of lanthanum carbonate, which is in a state of equilibrium while dissolving and precipitating in the water system, preferentially dissolving small particles, and after the small particles are dissolved, lanthanum carbonate is in a saturated state, and will precipitate on the interface of undissolved lanthanum carbonate in the system, causing lanthanum carbonate to grow), avoiding the growth of lanthanum source precursor particles, and the ammonium carbonate remaining in the precursor can be removed by high-temperature calcination and decomposition, which will not affect the purity of the material.

[0016] In the present invention, when preparing LSCF, the metal salt used is a water-soluble salt of lanthanum, strontium, cobalt, and iron; when preparing LSM, the metal salt used is a water-soluble salt of lanthanum, strontium, and manganese; when preparing LSC, the metal salt used is a water-soluble salt of lanthanum, strontium, and cobalt.

[0017] Furthermore, the mass concentration of the metal salt in the solution 1 is 10-30%. The concentration of the solution 1 is limited by the solubility of the metal salt in water. If the concentration is too low, the precursor yield will be affected.

[0018] Furthermore, the mass concentration of the coprecipitant in the solution 2 is 20-40%. The concentration of the solution 2 is limited by the solubility of the coprecipitant in water. If the concentration is too low, the precursor yield will also be affected.

[0019] Furthermore, the molar ratio of the coprecipitant to the metal salt is (3-10): 1. If the molar ratio of the coprecipitant to the metal salt is too low, the metal ions in the metal salt cannot be completely precipitated; if the molar ratio of the coprecipitant to the metal salt is too high, it will cause a waste of raw materials and a long cleaning time.

[0020] Furthermore, the mass concentration of the coprecipitant in the diluted solution 2 is 0.1-10%. If the concentration of the aqueous ammonium carbonate solution for washing the precursor is lower than 0.1%, the growth of the lanthanum source precursor particles cannot be inhibited; if the concentration of the aqueous ammonium carbonate solution for washing the precursor is higher than 10%, ammonium carbonate will be wasted.

[0021] Furthermore, the calcination temperature of the high temperature calcination is 700-1000°C, and the calcination time is not less than 1 hour. The calcination time of more than 1 hour can completely form a phase. If the calcination time is too long, the energy consumption will increase.

[0022] The beneficial effect of the present invention is that the present invention adopts an aqueous solution of a coprecipitant instead of pure water to wash the precursor, which can not only remove the acid radical ions brought in by the metal salt, but also inhibit the dissolution and precipitation of the lanthanum source precursor, avoid the growth of the lanthanum source precursor particles, and solve the problem that when the precursor is washed with pure water, the precursor cannot be completely phased during high-temperature calcination due to the growth of the lanthanum source precursor particles. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 XRD pattern of LSM prepared in Example 1;

[0024] Figure 2 XRD pattern of LSM prepared in Example 2;

[0025] Figure 3 XRD pattern of LSM prepared in Example 3;

[0026] Figure 4XRD pattern of LSM prepared in Example 4;

[0027] Figure 5 XRD pattern of LSM prepared in Example 5;

[0028] Figure 6 XRD pattern of LSM prepared in Example 6;

[0029] Figure 7 XRD pattern of LSM prepared in Example 7;

[0030] Figure 8 XRD pattern of LSM prepared in Example 8;

[0031] Fig. 9 XRD pattern of LSM prepared in Example 9;

[0032] Fig.10 XRD pattern of LSM prepared in Example 10;

[0033] Fig.11 is the XRD pattern of the LSM prepared in Example 11;

[0034] Fig.12 XRD pattern of LSM prepared in Example 12;

[0035] Fig.13 is the SEM image of the LSM prepared in Example 1;

[0036] Fig.14 This is the SEM image of the LSM prepared in Comparative Example 1. DETAILED DESCRIPTION

[0037] In order to make the technical means, creative features, objectives and effects achieved by the present invention easy to understand, the present invention is further described below in conjunction with specific embodiments and diagrams.

[0038] Example 1

[0039] Weigh lanthanum nitrate nonahydrate (34.64g, 0.08mol), strontium nitrate (4.23g, 0.02mol), 50wt% manganese nitrate aqueous solution (35.79g, 0.1mol) and 500g water, stir and dissolve completely to obtain a nitrate solution. Weigh ammonium carbonate (57.65g, 0.6mol) and 230g water, stir and dissolve completely to obtain an ammonium carbonate solution. Slowly add the nitrate solution to the ammonium carbonate solution using a peristaltic pump, stir for 30 minutes after the addition is completed, and obtain a precursor slurry. Filter the precursor slurry, wash the filter residue with 0.1% ammonium carbonate solution, and dry it to obtain a precursor. Place the precursor in a muffle furnace and calcine at 700°C for 1h to obtain LSM.

[0040] Embodiment 2-3

[0041] The method of Example 1 was followed, except that the calcination temperature was adjusted, as shown in Table 1.

[0042] Table 1

[0043] Calcination temperature (℃) Calcination time (h) XRD pattern of LSM Example 1 700 1 Figure 1 Example 2 850 1 Figure 2 Example 3 1000 1 Figure 3

[0044] Combination Figure 1 , Figure 2 and Figure 3 It can be seen that when the calcination temperature is 700-1000℃ and the calcination time is 1h, the product LSM has completely formed a phase. Increasing the calcination temperature will not change the product structure, but will increase energy consumption.

[0045] Embodiment 4-5

[0046] The method of Example 1 was followed, except that the usage ratio of ammonium carbonate to nitrate was adjusted, as shown in Table 2.

[0047] Table 2

[0048] Molar ratio of ammonium carbonate to nitrate XRD pattern of LSM Example 1 3:1 Figure 1 Example 4 6.5:1 Figure 4 Example 5 10:1 Figure 5

[0049] Combination Figure 1 , Figure 4 and Figure 5 It can be seen that when the molar ratio of ammonium carbonate to nitrate is (3-10):1, the product LSM has completely formed a phase. Increasing the molar ratio of ammonium carbonate to nitrate will not change the product structure, but will cause a waste of raw materials and increase the cost of raw materials. However, reducing the molar ratio of ammonium carbonate to nitrate will result in the inability to completely precipitate metal ions.

[0050] Embodiment 6-7

[0051] The method of Example 1 was followed, except that the concentration of the nitrate solution was adjusted, as shown in Table 3.

[0052] Table 3

[0053] Concentration of nitrate solution (%) XRD pattern of LSM Example 1 13 Figure 1 Example 6 10 Figure 6 Example 7 30 Figure 7

[0054] Combination Figure 1 , Figure 6 and Figure 7 It can be seen that when the concentration of the nitrate solution is 10-30%, the product LSM has completely formed a phase. If the concentration of the nitrate solution is higher than 30%, the viscosity of the slurry during coprecipitation will be too high, which is not conducive to post-processing. If the concentration of the nitrate solution is lower than 10%, it will affect the production efficiency.

[0055] Embodiments 8 to 9

[0056] The method of Example 1 was followed, except that the concentration of the ammonium carbonate solution for coprecipitation was adjusted, as shown in Table 4.

[0057] Table 4

[0058] Concentration of ammonium carbonate solution for coprecipitation (%) XRD pattern of LSM Example 1 20 Figure 1 Example 8 30 Figure 8 Example 9 40 Fig. 9

[0059] Combination Figure 1 , Figure 8 and Fig. 9 It can be seen that when the concentration of the ammonium carbonate solution for coprecipitation is 20-40%, the product LSM has completely formed a phase. If the concentration of the ammonium carbonate solution for coprecipitation is lower than 10%, the metal ions in the metal salt cannot be completely precipitated, thereby reducing the utilization rate of the raw materials. At the same time, the concentration of the ammonium carbonate solution for precipitation is also determined by the solubility of ammonium carbonate in water. Even if the concentration of the ammonium carbonate solution for coprecipitation can be increased to more than 40%, the excess ammonium carbonate may cause salt effect, coordination effect, etc., which increases the solubility of the precursor.

[0060] Examples 10-11 and Comparative Example 1

[0061] The method of Example 1 was followed, except that the concentration of the ammonium carbonate solution used for washing the precursor was adjusted, as shown in Table 5 for details.

[0062] Table 5

[0063] Concentration of ammonium carbonate solution for precursor washing (%) XRD pattern of LSM Example 1 0.1 Figure 1 Example 10 5 Fig.10 Embodiment 11 10 Fig.11 Comparative Example 1 0 Fig.12

[0064] Combination Figure 1 , Fig.10 , Fig.11 and Fig.12 It can be seen that when the concentration of the ammonium carbonate solution used for precursor washing is 0.1-10%, the product LSM has completely formed a phase. In comparative example 1, pure water is used as the detergent, and the XRD diagram of the obtained product has La2O2CO3 diffraction peaks at 2θ angles of 13° and 29.5°. This is because the precursor cannot react completely during the cleaning process due to the growth and aggregation of the lanthanum source precursor.

[0065] Fig.13 is the SEM image of the LSM prepared in Example 1; Fig.14 This is the SEM image of the LSM prepared in Comparative Example 1. Fig.13 and Fig.14 It can be seen that the LSM product of Example 1 has completely formed a phase, and the products are all small nanoparticles. There are more flakes in the product of Comparative Example 1, which is caused by the growth and aggregation of lanthanum precursor into large particles during the cleaning process, resulting in the inability to completely form a phase.

[0066] The above shows and describes the basic principles and main features of the present invention and the advantages of the present invention. It should be understood by those skilled in the art that the present invention is not limited to the above embodiments. The above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention to be protected. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A method for preparing a SOFC cathode material and an interconnect coating material, characterized in that: The following steps are involved: (1) dissolving a metal salt in water to obtain a solution 1; (2) dissolving the coprecipitant in water to obtain solution 2; (3) reacting solution 1 with solution 2 to obtain a precursor slurry; (4) filtering the precursor slurry, washing the filter residue with the diluted solution 2, and drying to obtain a precursor; (5) calcining the precursor at high temperature to obtain SOFC cathode material or interconnect coating material.

2. The method for preparing a SOFC cathode material and an interconnect coating material according to claim 1, characterized in that: The metal salt includes a water-soluble salt of a lanthanide metal, strontium, and at least one metal selected from manganese, cobalt, iron, nickel, bismuth, and barium.

3. The method for preparing the SOFC cathode material and the interconnect coating material according to claim 2, characterized in that: The water-soluble salt is selected from at least one of nitrates, chlorides, sulfates and acetates.

4. The method for preparing a SOFC cathode material and an interconnect coating material according to claim 1, characterized in that: The coprecipitant is ammonium carbonate.

5. The method for preparing a SOFC cathode material and an interconnect coating material according to any one of claims 1 to 3, characterized in that: The mass concentration of the metal salt in the solution 1 is 10-30%.

6. The method for preparing a SOFC cathode material and an interconnect coating material according to claim 1 or 4, characterized in that: The mass concentration of the coprecipitant in the solution 2 is 20-40%.

7. The method for preparing a SOFC cathode material and an interconnect coating material according to any one of claims 1 to 4, characterized in that: The molar ratio of the coprecipitant to the metal salt is (3-10):

1.

8. The method for preparing a SOFC cathode material and an interconnect coating material according to claim 1, characterized in that: The mass concentration of the coprecipitant in the diluted solution 2 is 0.1-10%.

9. The method for preparing a SOFC cathode material and an interconnect coating material according to claim 1, characterized in that: The calcination temperature of the high-temperature calcination is 700-1000° C., and the calcination time is not less than 1 hour.

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