A low-temperature carbonate melt reaction preparation method for metal-based solid oxide electrolyte membrane

Abstract

The present invention provides a low-temperature carbonate melt reaction method for preparing metal-based electrolyte films, providing a strategy for solving the key problem of different sintering temperatures of various parts of metal-based solid oxide batteries. The present invention introduces Na2CO3-K2CO3 eutectic salt, so that the high-melting-point precursor reactants are dissolved in the eutectic and react, and after reaching supersaturation, the target product crystals are precipitated and gradually grow and grow together, and finally a dense electrolyte film of the micron level can be obtained. The present invention utilizes a simple low-temperature eutectic reaction to transform the solid-solid system in the traditional sintering method into a solid-liquid system, which has faster mass transfer and reaction rates; compared with the physical film preparation method commonly used in metal-based solid oxide batteries, the carbonate low-temperature melt method is simple in process, does not require expensive equipment, can greatly reduce the cost and difficulty of preparing metal-based solid oxide batteries, and has industrial application potential.

Description

Technical Field

[0001] The invention belongs to the field of metal-based solid oxide electrolytes, and in particular relates to a method for densifying a metal-based electrolyte film at low temperature by utilizing a carbonate melt reaction. Background Art

[0002] Solid oxide fuel cells (SOFCs), electrochemical energy conversion devices that directly convert the chemical energy of fuels into electrical energy, are greener and more efficient than traditional fuel combustion power generation. However, traditional SOFCs face challenges in sealing, high material costs, and thermal shock resistance when operating at high temperatures, hindering their further development. Metal-supported solid oxide fuel cells (MS-SOFCs), third-generation SOFCs, use low-cost metal materials such as stainless steel as cell supports and connectors, addressing the challenges of traditional all-ceramic SOFC designs, such as poor strength, packaging difficulties, and long startup times.

[0003] The commonly used metal substrates for MS-SOFC are nickel-based and iron-based metals. Among them, Changsing Hwang et al. prepared La on a porous nickel metal substrate using atmospheric plasma spraying technology. 0.8 Sr 0.2 Ga 0.8 Mg 0.2 O 3-δ Electrolyte, followed by annealing at 1000 ° C. Compared with nickel-based metals, iron-based metals are cheaper and have a thermal expansion coefficient that is more compatible with ceramic electrolyte membranes. et al. prepared ScYSZ electrolyte on a stainless steel substrate using a co-sintering method and Ce using a magnetron sputtering method. 0.9 Gd 0.1 O 2-δ Isolation layer. Yan Dong et al. used Ni-Fe alloy as the metal substrate and prepared the electrolyte membrane by high-temperature co-sintering. The addition of Fe element can enhance the oxidation resistance of the nickel-based metal substrate. In general, the sintering temperatures of various materials in MS-SOFC are different. In order to prevent the metal substrate from sintering and oxidation at high temperatures, physical methods such as pulsed laser and physical vapor deposition are usually used to prepare the electrolyte membrane. Specific equipment is required and it is difficult to expand production, resulting in low electrolyte density and insufficient conductivity, which greatly increases the preparation cost and difficulty of metal-supported solid oxide batteries. Therefore, the important direction of MS-SOFC research at this stage is still to explore low-temperature, low-cost electrolyte membrane preparation processes. Summary of the Invention

[0004] To address the challenges of the prior art, the present invention provides a low-temperature densification method for metal-based solid oxide electrolyte membranes based on a carbonate melt reaction. Leveraging the significant advantages of melt growth, such as high crystal purity and good integrity, the present invention introduces a Na2CO3-K2CO3 eutectic salt, allowing high-melting-point precursors to dissolve and react in the eutectic. Upon reaching supersaturation, target product crystals precipitate and gradually grow and intergrow, ultimately yielding a micron-scale dense electrolyte film. This invention provides a strategy for addressing the critical issue of varying sintering temperatures in various components of metal-based solid oxide batteries.

[0005] The present invention provides a low-temperature densification method for a metal-based solid oxide electrolyte membrane based on a carbonate melt reaction, comprising the following steps:

[0006] (1) Metal powder and pore-forming agent powder are mixed, pressed into tablets, and calcined in an argon atmosphere to obtain a metal substrate.

[0007] (2) Precursor oxide powder is prepared into a precursor oxide slurry, the precursor oxide slurry is evenly coated on a metal substrate, and the precursor oxide slurry is calcined in air at a low temperature to remove organic matter, thereby obtaining a precursor oxide coating.

[0008] (3) Evenly mixing a certain amount of carbonate eutectic powder, precursor carbonate powder, and precursor oxide powder, transferring the mixture to an alumina crucible, and covering and embedding the mixture on the coating prepared in step (2).

[0009] (4) placing the crucible from step (3) into a tubular furnace for melt reaction in an argon atmosphere, and then acid-washing and drying the crucible after the reaction to obtain a dense metal-based solid oxide electrolyte membrane.

[0010] The metal powder is one of nickel powder and nano 430 stainless steel powder; the pore-forming agent powder is BaCO3 powder;

[0011] The precursor oxide powder is (ZrO2) 0.92 (Y2O3) 0.08 (8YSZ), which is a raw material for preparing electrolyte films;

[0012] The precursor carbonate powder is BaCO3, which is the raw material for preparing electrolyte film;

[0013] The carbonate eutectic powder is composed of a mixture of Na2CO3 and K2CO3. After melting, the eutectic powder dissolves the precursor carbonate powder and the precursor oxide powder, causing them to react with each other and providing a molten environment for crystal growth.

[0014] The melting points of the precursor carbonate and the precursor oxide are both higher than that of the carbonate eutectic powder.

[0015] Furthermore, in the above technical solution, in step (1), the particle size of the nickel powder is 500nm to 1μm, and the particle size of the nano 430 stainless steel powder is 100 to 500nm; (ZrO2) 0.92 (Y2O3) 0.08 The particle size of (8YSZ) is 10 nm to 200 nm.

[0016] Furthermore, in the above technical solution, in step (1), the pore-forming agent accounts for 20 to 40% of the total mass of the metal powder.

[0017] Furthermore, in the above technical solution, in step (1), the thickness of the pressed sheet is 1 to 1.2 mm.

[0018] Furthermore, in the above technical solution, in step (1), the calcination temperature of the metal substrate is 750-800° C., and the holding time is 5-10 hours.

[0019] Furthermore, in the above technical solution, in step (2), a surfactant (triethanolamine), a dispersant (butyl benzyl phthalate), a binder (polyvinyl butyral resin), a solvent (ethanol, butanone) and other organic substances are added to the precursor oxide slurry, and the precursor oxide powder is mixed with the surfactant, dispersant, binder, solvent and other organic substances to obtain a precursor oxide slurry; the percentage content of each component in the precursor oxide slurry is: 20-33wt% of precursor oxide powder, 41-51wt% of ethanol, 19-20wt% of butanone, 1-1.2wt% of triethanolamine, 3-4wt% of polyvinyl butyral resin, and 2-3wt% of butyl benzyl phthalate.

[0020] Furthermore, in the above technical solution, in step (2), the coating method is normal pressure or negative pressure immersion.

[0021] Furthermore, in the above technical solution, in step (2), the calcination temperature is 400-600° C. and the calcination time is 2-5 hours.

[0022] Furthermore, in the above technical solution, in step (3), the molar ratio of Na2CO3 to K2CO3 in the carbonate eutectic powder is 1.2 to 1.6:1, the eutectic point is 710°C, and the total amount of substance is 0.02 to 0.04 mol.

[0023] Furthermore, in the above technical solution, in step (3), the precursor carbonate BaCO3 powder accounts for 20 to 40 mol% of the carbonate eutectic powder.

[0024] Furthermore, in the above technical solution, in step (3), the added precursor carbonate BaCO3 is in excess of the precursor oxide 8YSZ powder, and the molar ratio of the metal elements in the precursor carbonate powder and the precursor oxide powder is 3:1 to 9:1, that is, Ba:(Zr+Y)=3:1 to 9:1 mol / mol.

[0025] Furthermore, in the above technical solution, in step (4), the melt reaction temperature is 750 to 800° C., and the reaction time is 12 to 48 hours.

[0026] Furthermore, in the above technical solution, in step (4), the acid cleaning is performed by soaking and cleaning with a 0.5M acetic acid solution overnight.

[0027] Furthermore, in the above technical solution, the thickness of the obtained dense ceramic membrane is 5 to 10 μm.

[0028] The present invention is beneficial in that:

[0029] (1) Using a simple low-temperature melt reaction to prepare the electrolyte film, the refractory reactant powder is dissolved in a suitable molten salt for reaction, thereby transforming the solid-solid system in the traditional sintering method into a more uniform solid-liquid system, greatly improving mass transfer and reaction rate and improving interface contact;

[0030] (2) A low-temperature electrolyte film densification technology has been developed. The densification temperature can be reduced to below 1000°C, which avoids the volatilization and segregation of substances and elements, is conducive to maintaining the stoichiometric ratio of the electrolyte membrane and preparing high-performance solid oxide electrolyte membranes;

[0031] (3) This method does not require sintering the electrolyte membrane under vacuum or inert atmosphere protection, which prevents the metal substrate from high-temperature oxidation and sintering failure while obtaining a dense electrolyte film, solving the key problem of different sintering temperatures of different parts of the metal-based SOFC.

[0032] (4) Compared with the physical film preparation method commonly used in metal-based SOFCs, the carbonate low-temperature melt method has a simple preparation process and does not require expensive equipment. It can greatly reduce the cost and difficulty of metal-based SOFC preparation and has the potential for industrial application. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 Schematic diagram of the principle of preparing metal-based dense electrolyte membrane by the low-temperature carbonate melt reaction method described in the present invention.

[0034] Figure 2The metal nickel substrate with added pore-forming agent prepared in step 1 of Example 1 of the present invention, wherein a) is the metal nickel substrate obtained after calcination with the pore-forming agent; b) is the metal substrate after calcination and then pickling to remove the pore-forming agent (the pore-forming agent in the metal substrate is removed by pickling to show the pore size morphology of the porous metal substrate. In the membrane formation process of the embodiment, the pore-forming agent is retained in the metal substrate for melt reaction until it is removed in pickling together with excess carbonate melt in step 3).

[0035] Figure 3 This is an electron microscope image of the precursor oxide coating prepared in step 2 of Example 1 of the present invention, where a) is the coating surface; b) is the coating cross-section.

[0036] Figure 4 This is an electron microscope image of the metal-based electrolyte membrane prepared in step 3 of Example 1 of the present invention, where a) is the surface of the electrolyte membrane; b) is the cross-section of the electrolyte membrane. DETAILED DESCRIPTION

[0037] The present invention is further described in the following examples, but is not intended to limit the present invention.

[0038] Example 1

[0039] Step 1: Prepare the nickel metal substrate. Weigh 1g of nickel powder (particle size 500nm-1μm) and 0.2g of BaCO3 in a mortar and grind them evenly. Use a φ20mm mold to compress the pellets to a thickness of approximately 1mm. Then, place the pellets in a tube furnace and slowly heat them to 800°C under an argon atmosphere at 100ml / min. Hold the temperature for 5 hours. During the low-temperature stage, slowly heat them to 500°C at a rate of 0.5°C / min, then to 800°C at a rate of 1°C / min.

[0040] Step 2: Prepare the precursor oxide coating. Use 10g of nano-8YSZ (particle size of about 10nm) and 10g of micro-nano 8YSZ (particle size of about 200nm) powder as starting materials, 50.4g of anhydrous ethanol and 20g of butanone as solvents, and 1.2g of triethanolamine as a surfactant and ball mill for 24h, then continue to add 3.6g of butyl benzyl phthalate and 2.7g of polyvinyl butyral as dispersants and adhesives and ball mill for 24h to obtain a uniformly dispersed 8YSZ slurry. 8YSZ is coated on the metal substrate by three repeated atmospheric pressure impregnations, with a single impregnation time of 1min, and then slowly heated to 400℃ in a muffle furnace at 0.5℃ / min and calcined for 3h to remove organic matter. The morphology of the obtained precursor oxide coating is as follows Figure 3 shown.

[0041] Step 3: Prepare BaZr 0.85 Y 0.15 O 3-δ(BZY) solid oxide electrolyte membrane. Weigh 0.04 mol of Na2CO3 and K2CO3 powder (wherein the ratio of Na2CO3 to K2CO3 is 1.5), 0.008 mol of BaCO3 powder and 0.0008 mol of nano 8YSZ powder (particle size of about 10 nm); that is, BaCO3 accounts for 20 mol% of the total mass of Na2CO3-K2CO3, and Ba:(Zr+Y)=9:1 mol / mol. After fully grinding and mixing, transfer to an alumina crucible, cover and embed the precursor oxide coating of step 2, and react at 800°C for 12h under an argon atmosphere of 100ml / min. Finally, soak in 0.5M acetic acid solution overnight to clean the excess carbonate melt and the BaCO3 pore-forming agent in the metal substrate. After drying, a metal-based BZY electrolyte membrane with a thickness of about 10μm and a morphology as shown below can be obtained. Figure 4 shown.

[0042] Example 2

[0043] Step 1: Preparation of nickel metal substrate. Same as step 1 in Example 1.

[0044] Step 2: Prepare a precursor oxide coating, same as step 2 in Example 1.

[0045] Step 3: Prepare a BZY solid oxide electrolyte membrane. Weigh 0.02 mol of Na2CO3 and K2CO3 powder (with a Na2CO3 to K2CO3 molar ratio of 1.2), 0.006 mol of BaCO3 powder, and 0.0009 mol of nano-8YSZ powder (particle size approximately 10 nm); that is, BaCO3 accounts for 30 mol% of the total Na2CO3-K2CO3 eutectic salt, with a Ba:(Zr+Y) ratio of 6:1 mol / mol. Grind and mix thoroughly, then transfer to an alumina crucible, cover with the 8YSZ coating from Step 2, and react at 800°C for 12 hours under a 100 ml / min argon atmosphere. After the reaction, soak and clean the mixture overnight in 0.5 M acetic acid solution and dry to obtain a dense metal-based BZY electrolyte membrane.

[0046] Example 3

[0047] Step 1: Preparation of nickel metal substrate. Weigh 1g of nickel powder (particle size 500nm-1μm) and 0.3g of BaCO3 in a mortar and grind them evenly. Use a φ20mm mold to compress the pellets to a thickness of approximately 1.1mm. Then, place the pellets in a tube furnace and slowly heat them to 750°C under an argon atmosphere at 100ml / min. Hold the temperature for 10 hours. During the low-temperature stage, heat them slowly to 500°C at a rate of 0.5°C / min, and then to 750°C at a rate of 1°C / min.

[0048] Step 2: Prepare a precursor oxide coating, same as step 2 in Example 1.

[0049] Step 3: Prepare a BZY solid oxide electrolyte membrane. Weigh 0.04 mol of Na2CO3 and K2CO3 powder (the molar ratio of Na2CO3 to K2CO3 is 1.6), 0.016 mol of BaCO3 powder, and 0.005 mol of nano-8YSZ powder (particle size approximately 10 nm); that is, BaCO3 accounts for 40 mol% of the total mass of Na2CO3-K2CO3, and Ba:(Zr+Y) = 3:1 mol / mol. Grind and mix thoroughly, then transfer to an alumina crucible, cover and embed the precursor oxide coating from step 2, and react at 800°C for 24 hours under a 100 ml / min argon atmosphere. Finally, rinse with 0.5 M acetic acid solution overnight and dry to obtain a metal-based BZY electrolyte membrane.

[0050] Example 4

[0051] Step 1: Preparation of nickel metal substrate. Same as step 1 in Example 1.

[0052] Step 2: Preparation of the precursor oxide coating. Using 20g of nano-8YSZ (particle size approximately 10nm) and 20g of micro-nano-8YSZ (particle size approximately 200nm) powder as starting materials, 50.4g of anhydrous ethanol and 20g of butanone as solvents, and 1.2g of triethanolamine as a surfactant, the mixture was ball-milled for 24 hours. Subsequently, 3.6g of butyl benzyl phthalate and 2.7g of polyvinyl butyral were added as dispersants and binders, and ball-milled for another 24 hours to obtain a uniformly dispersed 8YSZ slurry. Using a suction flask and applying a pressure of -0.05MPa, the 8YSZ slurry was coated onto a nickel metal substrate by negative pressure dip coating for 1 minute. The mixture was then heated slowly to 400°C in a muffle furnace at 0.5°C / min and calcined for 3 hours to remove organic matter.

[0053] Step 3: Prepare a BZY solid oxide electrolyte membrane. Weigh 0.03 mol of Na2CO3 and K2CO3 powder (where the molar ratio of Na2CO3 to K2CO3 is 1.5), 0.006 mol of BaCO3 powder, and 0.0009 mol of nano-8YSZ powder (particle size approximately 10 nm); that is, BaCO3 accounts for 20 mol% of the total mass of Na2CO3-K2CO3, and Ba:(Zr+Y) = 6:1 mol / mol. After thorough grinding and mixing, transfer to an alumina crucible, cover and embed the precursor oxide coating from step 2, and react at 750°C for 48 hours under a 100 ml / min argon atmosphere. Finally, use 0.5 M acetic acid solution to clean the excess carbonate melt and the BaCO3 pore-forming agent in the metal substrate overnight. After drying, the metal-based BZY electrolyte membrane is obtained.

[0054] Example 5

[0055] Step 1: Preparation of 430 stainless steel substrate. Weigh 1 g of 430 stainless steel powder (particle size approximately 100 nm) and 0.4 g of the pore-forming agent BaCO3 in a mortar and grind them uniformly. Use a 20 mm diameter mold to compress the pellets to a thickness of approximately 1.2 mm. Then, place the pellets in a tube furnace and slowly heat them to 750°C under an argon atmosphere at 100 ml / min. Hold the temperature for 10 hours. During the low-temperature stage, heat the pellets at 0.5°C / min to 500°C, and then at 1°C / min to 750°C.

[0056] Step 2: Prepare a precursor oxide coating, same as step 2 in Example 1.

[0057] Step 3: Prepare a BZY solid oxide electrolyte membrane. Same as step 3 in Example 1.

[0058] Many embodiments can be listed above. For example, the grain size of the electrolyte membrane can be changed by adjusting the reaction temperature or time. In addition, the density of the electrolyte membrane can be further improved by repeated growth. The ratio of the carbonate eutectic to the precursor carbonate and the ratio of the precursor carbonate to the precursor oxide can be adjusted. In theory, as long as the precursor carbonate and the precursor oxide can be dissolved in the molten eutectic salt to react, and the target product can reach supersaturation in the melt and precipitate, a dense film can be prepared according to the carbonate melt reaction method proposed in the present invention.

Claims

1. A method for low-temperature densification of a metal-based solid oxide electrolyte membrane based on a carbonate melt reaction, characterized in that: The method comprises the following steps: (1) mixing metal powder with a pore-forming agent, pressing into tablets, and calcining to obtain a metal substrate; (2) preparing a precursor oxide powder into a slurry, uniformly coating the slurry on a metal substrate, and calcining the slurry to remove organic matter, thereby obtaining a precursor oxide coating; (3) uniformly mixing the carbonate eutectic powder with the precursor carbonate powder and the precursor oxide powder, transferring the mixture to an alumina crucible, and covering and encapsulating the coating prepared in step (2); (4) placing the crucible from step (3) into a tubular furnace for melt reaction, followed by pickling and drying to obtain a metal-based electrolyte film; The metal powder is one of nickel powder and nano 430 stainless steel powder, the pore forming agent is BaCO3 powder, and the precursor oxide powder is (ZrO2) 0.92 (Y2O3) 0.08 , the precursor carbonate powder is BaCO3, and the carbonate eutectic powder is composed of Na2CO3 and K2CO3.

2. The method according to claim 1, characterized in that In step (1), the calcination temperature is 750-800° C., and the calcination time is 5-10 hours.

3. The method according to claim 1, characterized in that In step (1), the pore-forming agent accounts for 20 to 40% of the mass of the metal powder.

4. The method according to claim 1, wherein In step (3), the molar ratio of Na2CO3 to K2CO3 in the carbonate eutectic powder is 1.2 to 1.6, the eutectic point is 710°C, and the total amount of the substance is 0.02 to 0.04 mol.

5. The method according to claim 1, wherein In step (3), the precursor carbonate powder accounts for 20 to 40 mol% of the carbonate eutectic powder.

6. The method according to claim 1, characterized in that In step (3), the molar ratio of the metal elements in the precursor carbonate powder to the precursor oxide powder is 3:1 to 9:

1.

7. The method according to claim 1, characterized in that In step (2), triethanolamine, butyl benzyl phthalate, polyvinyl butyral resin, ethanol, and butanone are further added to the slurry, and the percentage of each component in the slurry is: 20-33wt% of precursor oxide powder, 41-51wt% of ethanol, 19-20wt% of butanone, 1-1.2wt% of triethanolamine, 3-4wt% of polyvinyl butyral resin, and 2-3wt% of butyl benzyl phthalate.

8. The method according to claim 1, characterized in that In step (4), the temperature of the melt reaction is 750-800° C.; and the reaction time is 12-48 hours.

9. The method according to claim 1, characterized in that In step (2), the coating method is atmospheric pressure or negative pressure impregnation; the calcination temperature is 400-600° C., and the calcination time is 2-5 hours.

10. The method according to claim 1, characterized in that The thickness of the obtained metal-based electrolyte film is 5 to 10 μm.

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