Solid oxide fuel cell cathode material and preparation method thereof

Abstract

The present invention provides a solid oxide fuel cell cathode material and a preparation method thereof, wherein the preparation method comprises the following steps: Step S1, A 1‑x Sr x Co 1‑y Fe y O 3‑δ Mixed with Al2O3 particles to obtain mixed powder, wherein 0.2

Description

Technical Field

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

[0002] Solid oxide fuel cell technology is a new type of electrochemical power generation technology, which has the characteristics of environmental friendliness, high efficiency, no pollution, and no noise. However, the cathode catalyst particles of solid oxide fuel cells are prone to coarsening under high-temperature operation, resulting in long-term performance degradation of the battery. There are bottlenecks in long-term stability, which restricts its large-scale application.

[0003] In order to improve the lifespan of fuel cells, researchers have done a lot of work. For example, Chinese Patent CN110391426A discloses a method for improving the long-term stability of the cathode of a solid oxide fuel cell, in which a method of impregnation and electrospinning is proposed to prepare a cathode of a solid oxide fuel cell with LSCF nanoparticles, and the lifespan is extended by reducing the initial size, but the problem of particle coarsening is not solved. Chinese Patent CN112670521A discloses a method for improving the stability of the cathode of a solid oxide fuel cell based on stress design, in which a compressive stress is generated inside the electrode in the form of second-phase coating to inhibit the precipitation of Sr, thereby extending the lifespan, but the problem of electrode particle coarsening is not solved either. It can be seen that the existing methods for improving the stability of the cathode of a solid oxide fuel cell have not solved the problem of particle coarsening. Summary of the Invention

[0004] Aiming at the above technical problems, the present invention discloses a cathode material for a solid oxide fuel cell and a preparation method thereof, achieving the effect of inhibiting the coarsening of cathode material particles.

[0005] For this, the technical solution adopted by the present invention is as follows:

[0006] A preparation method for a cathode material of a solid oxide fuel cell includes the following steps:

[0007] Step S1, mixing A 1-x Sr x Co 1-y Fe y O 3-δ with Al2O3 particles uniformly to obtain a mixed powder, where 0.2 < x < 0.6, 0 < y < 1, and A is La or Ba; in the mixed powder, the mass ratio of Al2O3 particles is 5–15%; where δ represents oxygen vacancies and depends on A 1-x Sr x Co 1-y Fe y O 3-δThe material itself and the surrounding gas atmosphere;

[0008] Step S2: Mix the mixed powder with an ink vehicle to prepare a cathode slurry, and apply the cathode slurry to the surface of the battery electrolyte for high-temperature sintering. The ink vehicle is made of materials from the prior art.

[0009] By adopting this technical solution, alumina is added to the cathode material powder, and strontium aluminate SrAl2O4 can be generated in situ during the high-temperature sintering process. The strontium aluminate particles act as a coarsening inhibitor, which can inhibit the coarsening of the cathode material particles, making the cathode material particles smaller in size after sintering.

[0010] Furthermore, the mass ratio of the mixed powder to the ink vehicle is 2:1 to 1:2.

[0011] As a further improvement of the present invention, the sintering temperature is 1000-1300° C. More preferably, the sintering temperature is 1100-1300° C. More preferably, the sintering temperature is 1100° C.

[0012] As a further improvement of the present invention, the sintering time is 0.5-5 hours. More preferably, the sintering time is 2 hours.

[0013] As a further improvement of the present invention, the A 1-x Sr x Co 1-y Fe y O 3-δ For La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3-δ .

[0014] As a further improvement of the present invention, in the mixed powder, the mass ratio of Al2O3 particles is 10-15%.

[0015] The present invention also discloses a solid oxide fuel cell cathode material, which is prepared by using any one of the above methods for preparing a solid oxide fuel cell cathode material.

[0016] The present invention also discloses a solid oxide fuel cell, which comprises the solid oxide fuel cell cathode material as described above.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] By adopting the technical solution of the present invention, alumina is added to the cathode material powder, so that the cathode material generates nano-sized strontium aluminate (SrAl2O4) particle coarsening inhibitor in situ during the sintering preparation process, thereby achieving the effect of inhibiting the coarsening of the cathode material particles. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is the X-ray diffraction (XRD) pattern of the cathode material obtained by sintering in Example 1 of the present invention.

[0020] Figure 2 These are the surface scanning electron microscope (SEM) images and energy dispersive X-ray spectroscopy (EDX) images of the cathode material obtained by sintering in Example 1 of the present invention; wherein, (a) is the surface SEM image, and the white straight line in the image is the EDX line scan position; (b) is the EDX line scan element content change diagram.

[0021] Figure 3 This is the XRD spectrum of the cathode materials obtained by sintering Example 2 and Example 3 of the present invention.

[0022] Figure 4 It is a surface SEM comparison picture of the cathode materials obtained in Example 1, Example 4 and Example 5 of the present invention and the pure LSCF6428 after sintering (Comparative Example 1); wherein, (a) is Comparative Example 1, pure LSCF6428; (b) is Example 4, with an Al2O3 mass proportion of 5%; (c) is Example 1, with an Al2O3 mass proportion of 10%; (d) is Example 5, with an Al2O3 mass proportion of 15%.

[0023] Figure 5 It is a statistical histogram comparison of the particle size of the cathode materials obtained in Examples 1, 4 and 5 of the present invention and pure LSCF6428 (Comparative Example 1) after sintering; wherein, (a) is Comparative Example 1, pure LSCF6428; (b) is Example 4, with an Al2O3 mass proportion of 5%; (c) is Example 1, with an Al2O3 mass proportion of 10%; (d) is Example 5, with an Al2O3 mass proportion of 15%.

[0024] Figure 6 This is a trend diagram of the polarization resistance of the cathode material obtained by sintering Example 6 of the present invention changing with time. DETAILED DESCRIPTION

[0025] The preferred embodiments of the present invention are described in further detail below.

[0026] Example 1

[0027] A solid oxide fuel cell cathode material is prepared by the following steps:

[0028] (1) La0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3-δ The (LSCF6428) electrode material is mixed with Al2O3 particles to obtain a mixed powder LSCF6428-Al2O3, in which the mass ratio of Al2O3 is 10%.

[0029] (2) The mixed powder was pressed into a pellet and sintered at 1100°C for 2 hours to obtain a sample.

[0030] The XRD patterns of the obtained samples are as follows: Figure 1 As shown, it is obvious from XRD that strontium aluminate (SrAl2O4) is produced after sintering.

[0031] The samples were characterized by SEM combined with EDX. Figure 2 As shown, it can be found that the dark gray particles have higher Sr and Al contents. Compared with XRD characterization, it can be confirmed that the dark gray particles are strontium aluminate (SrAl2O4) particles, while the light gray particles are LSCF6428 particles.

[0032] Example 2

[0033] Based on Example 1, the difference of this example is that the sintering temperature of the mixed powder after tableting is 1200° C., and the rest is the same as Example 1.

[0034] Example 3

[0035] Based on Example 1, the difference of this example is that the sintering temperature of the mixed powder after tableting is 1300° C., and the rest is the same as Example 1.

[0036] The results of XRD characterization of Example 2 and Example 3 are as follows. Figure 3 As shown, it can be found that after sintering, strontium aluminate (SrAl2O4) is produced.

[0037] Example 4

[0038] Based on Example 1, the difference of this example is that the mass ratio of Al2O3 in the mixed powder is 5%, and the rest is the same as Example 1.

[0039] Example 5

[0040] Based on Example 1, the difference of this example is that the mass ratio of Al2O3 in the mixed powder is 15%, and the rest is the same as Example 1.

[0041] Comparative Example 1

[0042] Pure La0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3-δ (LSCF6428) was used as a comparative example, which was pressed into a tablet and sintered at 1100°C for 2 hours to obtain a comparative example 1 sample.

[0043] The surfaces of Example 1, Example 4, Example 5 and Comparative Example 1 were observed by scanning electron microscopy (SEM). Figure 4 As shown, the particle size of LSCF6428 was also counted. Figure 5 The particle size is shown in Table 1 as a histogram of the statistical results. It can be seen that the addition of Al2O3 can significantly reduce the particle size of LSCF6428 and solve the problem of electrode particle coarsening. The higher the mass fraction, the smaller the particle size.

[0044] Table 1 LSCF6428 particle size of Examples 1 to 3 and Comparative Example 1

[0045] sample Comparative Example 1 Example 1 Example 2 Example 3 Average grain size (μm) 3.83 1.57 2.14 1.06

[0046] Example 6

[0047] Based on Example 1, the mixed powder and ink binder were mixed in a mass ratio of 1:1 to prepare cathode slurry, and the cathode slurry was coated on the electrolyte surface and sintered at high temperature. The sintering temperature was 1100°C and the sintering time was 2h to prepare a three-electrode half-cell. 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3-δ (LSCF6428) was used as a comparative example. The ink vehicle in this embodiment was a commercially available ink vehicle.

[0048] At an operating temperature of 800°C, the half-cell was subjected to a 0.5 A / cm 2 The electrochemical impedance spectroscopy was used to obtain the relationship between the polarization resistance of the electrode material and the time. Figure 6 As shown in the figure, compared with pure LSCF6428 without any addition, the polarization resistance of the LSCF6428 electrode with 10% Al2O3 added by mass increases more slowly and has more stable performance. This shows that Al2O3 can inhibit the particle coarsening trend of solid oxide fuel cells during long-term high-temperature operation and extend their operating life.

[0049] The above is a further detailed description of the present invention in conjunction with specific preferred embodiments, and the specific implementation of the present invention should not be considered to be limited to these descriptions. For those skilled in the art to which the present invention belongs, several simple deductions or substitutions can be made without departing from the concept of the present invention, and all of these should be considered to fall within the scope of protection of the present invention.

Claims

1. A method for preparing a cathode material for a solid oxide fuel cell, characterized in that: The steps include: Step S1, mix A 1-x Sr x Co 1-y Fe y O 3-δ with Al2O3 particles evenly to obtain a mixed powder, where 0.2 < x < 0.6, 0 < y < 1, and A is La or Ba; in the mixed powder, the mass ratio of Al2O3 particles is 5–15%; Step S2: Mix the mixed powder with the ink connector to prepare a cathode slurry, apply the cathode slurry on the surface of the battery electrolyte and sinter it to generate nano-sized strontium aluminate particles in situ; the sintering temperature is 1000-1300°C.

2. The method for preparing a cathode material for a solid oxide fuel cell according to claim 1, wherein: The sintering time is 0.5-5 hours, and the sintering temperature is 1100°C.

3. The method for preparing a cathode material for a solid oxide fuel cell according to claim 1, wherein: The A 1-x Sr x Co 1-y Fe y O 3-δ For La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3-δ .

4. The method for preparing a cathode material for a solid oxide fuel cell according to any one of claims 1 to 3, wherein: In the mixed powder, the mass ratio of Al2O3 particles is 10-15%.

5. A solid oxide fuel cell cathode material, characterized in that: The solid oxide fuel cell cathode material is prepared by the method for preparing the solid oxide fuel cell cathode material according to any one of claims 1 to 4.

6. A solid oxide fuel cell, characterized in that: It comprises the solid oxide fuel cell cathode material according to claim 5.

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