Pretreatment method of nickel oxide powder for preparing SOFC anode

Abstract

The invention discloses a pretreatment method of nickel oxide powder for SOFC anode preparation, and relates to the technical field of solid oxide fuel cells, the nickel oxide powder is subjected to high temperature calcination and crushing, and the pretreatment of the nickel oxide powder can be completed; according to the preparation method, the nickel oxide powder is subjected to pretreatment of high-temperature calcination and then crushing, and nickel oxide in the powder can react with impurities through calcination; the pretreated nickel oxide powder is applied to preparation of an SOFC anode, the problem that black spot protrusions exist on the surfaces of a NiO / YSZ film material and a Ni / YSZ film material due to local abnormal growth of nickel oxide particles cannot occur when a biscuit is subjected to high-temperature sintering, and then the situation that an electrolyte layer is damaged due to the existence of the black spot protrusions is avoided.

Description

Technical Field

[0001] The invention relates to the technical field of solid oxide fuel cells, and in particular to a pretreatment method for nickel oxide powder for preparing SOFC anodes. 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] SOFC consists of three parts: a porous anode layer, a dense electrolyte layer and a porous cathode layer. The anode material of SOFC should have a porous structure to ensure the transportation of reaction gases, increase the three-phase reaction interface of electrode, electrolyte and fuel gas, and make the anode reaction easier.

[0004] Currently, the most commonly used anode material is a composite metal ceramic of nickel (Ni) and yttrium-stabilized zirconia (YSZ), which is mainly prepared by pre-preparing a NiO / YSZ membrane and then reducing NiO in a reducing environment to obtain a Ni / YSZ anode.

[0005] When preparing a single cell, the electrolyte is generally coated on the NiO / YSZ membrane and then co-sintered. Since the thickness of the electrolyte layer is only 4 to 10 μm, the flatness of the NiO / YSZ membrane is extremely important, and there should be no abnormal protrusions on the surface, otherwise it will damage the electrolyte layer and cause battery leakage.

[0006] When the researchers used the currently available industrial grade nickel oxide to prepare the NiO / YSZ membrane, they found that there were many black spots on the membrane after sintering, forming bulges. When co-sintered with the electrolyte layer, the bulges on the surface of the NiO / YSZ membrane would damage the electrolyte layer, causing gas leakage in the single cell. Summary of the invention

[0007] The technical problem to be solved by the present invention is to provide a pretreatment method for nickel oxide powder for preparing SOFC anodes. The pretreated nickel oxide powder is used to prepare NiO / YSZ membrane materials, which can effectively reduce the protrusions formed by black spots on the surface of the membrane material and avoid damage to the electrolyte layer.

[0008] The technical problem to be solved by the present invention is achieved by adopting the following technical solutions:

[0009] One of the purposes of the present invention is to provide a method for pretreating nickel oxide powder for preparing SOFC anodes. The pretreatment of nickel oxide powder can be completed by calcining the nickel oxide powder at high temperature and crushing it.

[0010] A second object of the present invention is to provide a method for preparing a NiO / YSZ film material for a SOFC anode, comprising the following steps:

[0011] (1) adding YSZ powder, nickel oxide powder treated by the aforementioned pretreatment method, and a binder into a solvent, mixing them evenly, to obtain a slurry;

[0012] (2) tape-casting the slurry and drying it to obtain a green blank;

[0013] (3) Sintering the green blank at high temperature to obtain NiO / YSZ film material.

[0014] The beneficial effects of the present invention are as follows: the present invention performs a pretreatment of high-temperature calcination and then crushing on nickel oxide powder, and the calcination allows the nickel oxide in the powder to react with impurities; the pretreated nickel oxide powder is used to prepare SOFC anodes, and when the green blank is sintered at high temperature, the problem of black spot protrusions on the surfaces of NiO / YSZ film materials and Ni / YSZ film materials due to the abnormal growth of local nickel oxide particles will not occur, thereby avoiding the damage of the electrolyte layer caused by the existence of the black spot protrusions. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is a sample picture prepared in Example 1;

[0016] Figure 2 This is a sample picture prepared in Example 2;

[0017] Figure 3 This is a sample picture prepared in Example 3;

[0018] Figure 4 This is a sample picture prepared in Comparative Example 1;

[0019] Figure 5 This is a sample picture prepared in Example 4;

[0020] Figure 6 This is a sample picture prepared in Example 5;

[0021] Figure 7 This is a sample picture prepared in Example 6;

[0022] Figure 8 This is a sample picture prepared in Comparative Example 2;

[0023] Fig. 9 This is a sample picture prepared in Comparative Example 3;

[0024] Fig.10 The EDS test results of black spots in the sample prepared in Comparative Example 3;

[0025] Fig.11 This is a sample picture prepared in Comparative Example 4. DETAILED DESCRIPTION

[0026] 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.

[0027] The invention provides a method for pretreating nickel oxide powder for preparing SOFC anode. The pretreating of the nickel oxide powder can be completed by calcining the nickel oxide powder at high temperature and crushing the nickel oxide powder.

[0028] Furthermore, the particle size D50 of the nickel oxide powder before pretreatment is 1 to 5 μm.

[0029] Furthermore, the high temperature calcination temperature is 1200-1400°C and the time is 0.5-10h. If the calcination temperature is higher than 1400°C, the pretreatment energy consumption will be too large; if the calcination temperature is lower than 1200°C, the technical problem to be solved by the present invention cannot be solved.

[0030] Furthermore, the crushing method is dry ball milling. Dry ball milling has the advantages of simple operation, high processing efficiency, low energy consumption, and easy large-scale production, and can also obtain powders with good particle size uniformity and controllable particle size range.

[0031] Furthermore, the particle size D50 of the nickel oxide powder after pretreatment is 1 to 5 μm.

[0032] The present invention also provides a method for preparing a NiO / YSZ film material for a SOFC anode, comprising the following steps:

[0033] (1) adding YSZ powder, nickel oxide powder treated by the aforementioned pretreatment method, and a binder into a solvent, mixing them evenly, to obtain a slurry;

[0034] (2) tape-casting the slurry and drying it to obtain a green blank;

[0035] (3) Sintering the green blank at high temperature to obtain NiO / YSZ film material.

[0036] Furthermore, the binder includes but is not limited to one or more of polyvinyl butyral (PVB), carboxymethyl cellulose (CMC), polyvinyl alcohol (PVA), polyether sulfone (PESf), and polyvinyl pyrrolidone (PVP).

[0037] Furthermore, the solvent includes but is not limited to one or more of ethanol, water, ethylene glycol, and butanone. When preparing the slurry, ball milling can be used to improve the dispersion uniformity of the YSZ powder, nickel oxide powder, and binder in the solvent, increase the specific surface area of ​​the particles, and reduce the resistivity of the slurry, thereby improving the battery performance.

[0038] Furthermore, the mass ratio of the YSZ powder to the pretreated nickel oxide powder and the binder is (30-40):(60-70):(1-5).

[0039] Furthermore, the mixing method is wet ball milling. On the one hand, wet ball milling can break up the solid particles in the slurry, and on the other hand, wet ball milling can make the slurry components uniform.

[0040] Furthermore, the high temperature sintering temperature is 1300-1450° C., and the time is 1-2 hours.

[0041] Furthermore, the surface of the NiO / YSZ film material has no black spot protrusions.

[0042] Furthermore, the NiO / YSZ film material is reduced in a hydrogen atmosphere to prepare a Ni / YSZ film material.

[0043] Example 1

[0044] Step 1. Weigh 100g of nickel oxide powder (particle size D50 = 2μm) and calcine it in a muffle furnace at 1200°C for 2h; add the calcined solid into a 500mL ball mill, add 500g of zirconium beads with a diameter of 2mm into the ball mill, ball mill at a speed of 500r / min to a particle size D50 of 2μm, and dry in an oven at 150°C to a water content of less than 0.3wt%, to complete the pretreatment of the nickel oxide powder.

[0045] Step 2: Add 2 g PVB, 67 g ethanol, 40 g YSZ powder (particle size D50 = 0.5 μm), 60 g nickel oxide (particle size D50 = 2 μm) and 500 g zirconium beads with a diameter of 2 mm into a 500 mL ball mill, and ball mill at a speed of 500 r / min for 24 h to obtain a slurry; tape-cast the slurry and dry it at 105 ° C for 24 h to obtain a blank; cut the blank into 118 mm × 118 mm square pieces, sinter it in a muffle furnace at 1450 ° C for 2 h to obtain a sample.

[0046] Examples 2 to 6 and Comparative Examples 1 to 2

[0047] The method of Example 1 was followed, except that the calcination temperature or calcination time of the nickel oxide powder during pretreatment was adjusted, as shown in Table 1. The surfaces of the samples prepared in Examples 1 to 3 and Comparative Examples 1 to 2 were observed to see if there were black spots. The results are shown in Table 1.

[0048] Table 1

[0049]

[0050]

[0051] Combination Figures 1 to 4 It can be seen that when the calcination temperature of nickel oxide powder is controlled at 1200-1400℃ during pretreatment, there are no black spots on the surface of the prepared sample; when the calcination temperature is lower than 1200℃, more black spots will appear on the surface of the prepared sample; of course, the calcination temperature can be higher than 1400℃, but it will increase energy consumption. Therefore, it is recommended that the calcination temperature of nickel oxide powder be controlled at 1200-1400℃ during pretreatment.

[0052] Combination Figures 5 to 8 It can be seen that when the calcination time of nickel oxide powder is controlled within 0.5 to 10 hours during pretreatment, there are no black spots on the surface of the prepared sample; when the calcination time is less than 0.5 hours, more black spots will appear on the surface of the prepared sample, because the nickel oxide in the nickel oxide powder does not react completely with the impurities; of course, the calcination time can be greater than 10 hours, but it will increase energy consumption. Therefore, it is recommended that the calcination time of nickel oxide powder be controlled within 0.5 to 10 hours during pretreatment.

[0053] Comparative Example 3

[0054] The method of Example 1 was followed, except that the nickel oxide powder was not pretreated, but the sample was directly prepared using nickel oxide powder (particle size D50 = 2 μm). By observing the sample prepared in Comparative Example 3, it can be found that there are many black spots on its surface, such as Fig. 9 shown.

[0055] Combination Fig. 9 It can be seen that if the nickel oxide powder is directly prepared without pretreatment, more black spots will appear on the surface of the prepared sample. This is because the nickel oxide in the blank reacts with the impurities in the nickel oxide during high-temperature sintering.

[0056] right Fig. 9 The black dots in the figure were subjected to X-ray energy dispersive spectroscopy (EDS) analysis. The results are shown in Fig.10 .Depend on Fig.10 It can be seen that in addition to nickel elements (main body), the black spots also contain impurity elements such as Al and Fe. This shows that impurity elements such as Al and Fe may cause the local abnormal growth of nickel oxide particles, forming black spot protrusions.

[0057] Comparative Example 4

[0058] The method of Example 2 is followed, except that a small amount of iron oxide is added to the surface of the green body before the green body is subjected to high temperature sintering. By observing the sample prepared in Comparative Example 4, it can be found that there are many black spots protruding on its surface, such as Fig.11 shown.

[0059] Combination Fig.11 It can be seen that a small amount of iron oxide was added to the surface of the green billet before high-temperature sintering, and more black spots appeared on the surface of the prepared sample. This is due to the reaction between iron oxide and nickel oxide during high-temperature sintering.

[0060] 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 pretreating nickel oxide powder for preparing SOFC anodes, characterized in that: The pretreatment of nickel oxide powder can be completed by calcining and crushing the nickel oxide powder at high temperature.

2. The pretreatment method according to claim 1, characterized in that: The particle size D50 of the nickel oxide powder before pretreatment is 1 to 5 μm.

3. The pretreatment method according to claim 1, characterized in that: The high temperature calcination temperature is 1200-1400° C. and the time is 0.5-10 hours.

4. The pretreatment method according to claim 1, characterized in that: The crushing method is dry ball milling.

5. The pretreatment method according to claim 1, characterized in that: The particle size D50 of the nickel oxide powder after pretreatment is 1 to 5 μm.

6. A method for preparing a NiO / YSZ film material for SOFC anode, characterized in that: The following steps are involved: (1) adding YSZ powder, nickel oxide powder treated by the pretreatment method according to any one of claims 1 to 5, and a binder into a solvent, mixing them evenly to obtain a slurry; (2) tape-casting the slurry and drying it to obtain a green blank; (3) Sintering the green blank at high temperature to obtain NiO / YSZ film material.

7. The preparation method according to claim 6, characterized in that: The binder is one or more of PVB, CMC, PVA, PESf, and PVP; Preferably, the solvent is one or more of ethanol, water, ethylene glycol and butanone.

8. The preparation method according to claim 6, characterized in that: The mass ratio of the YSZ powder to the pretreated nickel oxide powder and the binder is (30-40):(60-70):(1-5).

9. The preparation method according to claim 6, characterized in that: The high temperature sintering temperature is 1300-1450° C. and the time is 1-2 hours.

10. The preparation method according to claim 6, characterized in that: The surface of the NiO / YSZ film material has no black spot protrusions.

Images