A cerium oxide-based composite electrolyte material and preparation method thereof

Abstract

A cerium oxide-based composite electrolyte material and a preparation method thereof, relating to the technical field of solid oxide fuel cells, comprising Ce 0.8 (SmLaPrYM) 0.04 O 2‑δ Nanopowder and La 1.9 Ba 0.1 Mo 1.85 W 0.15 O 8.95 The nanopowder is composited and then sintered to prepare it. The present invention uses a sol-gel method improved with activated carbon to prepare pure-phase high-entropy nanopowders with a cubic fluorite structure by optimizing high-entropy components and controlling the preparation process. This solves the problem that traditional preparation methods are difficult to obtain pure-phase high-entropy ceramic powders due to uneven mixing and incomplete reactions. The material can be densified at a lower temperature (1200°C). The prepared composite electrolyte has high ionic conductivity and low activation energy in the medium temperature range (600-800°C), which can meet the use requirements of medium-temperature SOFCs.

Description

Technical Field

[0001] The present invention relates to the technical field of solid oxide fuel cells, and in particular to a cerium oxide-based composite electrolyte material and a preparation method thereof. Background Art

[0002] Solid oxide cells (SOFCs) have become a very promising clean energy conversion technology due to their good stability, high power density, environmental friendliness and pollution-free. The current commercialization process of SOFCs still requires continuous innovation in materials and manufacturing processes to improve battery life and reduce battery operating temperature. To reduce the operating temperature of SOFCs, it is necessary to develop electrolyte materials with high conductivity at medium and low temperatures. Cerium oxide-based electrolytes are one of the most promising medium and low temperature solid electrolyte materials. Its conductivity at medium and low temperatures is an order of magnitude higher than that of traditional YSZ electrolytes, and it has a lower conductivity activation energy. However, cerium oxide-based materials need to be sintered densely at high temperatures (>1400°C), and Ce under high temperature or reducing environment conditions. 4+ Easily reduced to Ce 3+ How to improve the stability of ceria-based materials while maintaining high conductivity and low activation energy has become a hot topic and difficulty in the research of ceria-based electrolyte materials.

[0003] "High entropy" is a new material design theory that has emerged in recent years. High entropy can lead to a "cocktail" effect in performance, and it has become a hot topic in materials research. In 2015, the concept of "high entropy" was applied to the research of oxide ceramic materials, achieving breakthrough progress. Compared with traditional ceramic materials, high-entropy ceramics possess excellent structural stability, superior mechanical properties, and outstanding electrical properties, showing potential application value in high-temperature materials and new energy materials. Research on the application of high-entropy ceramic materials in SOFCs has been increasing in recent years.

[0004] The present invention attempts to prepare pure phase high entropy cerium oxide-based oxide nanopowder by optimizing high entropy components and combining it with high conductivity and low melting point La 1.9 Ba 0.1 Mo 1.85 W 0.15 O 8.95 It is expected that under low-temperature preparation conditions, a cerium oxide-based composite electrolyte material with higher ionic conductivity and lower activation energy can be obtained. Summary of the Invention

[0005] The purpose of the present invention is to provide a cerium oxide-based composite electrolyte material and a preparation method thereof, wherein pure phase high entropy cerium oxide-based oxide nanopowder is prepared by optimizing high entropy components and controlling the preparation process, and the high conductivity and low melting point La 1.9 Ba 0.1 Mo 1.85 W 0.15 O 8.95 High-performance cerium oxide-based composite electrolyte materials are prepared under low temperature conditions to solve the bottleneck problems of existing cerium oxide-based electrolytes that are difficult to sinter and have poor stability.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is:

[0007] A cerium oxide-based composite electrolyte material, comprising Ce 0.8 (SmLaPrYM) 0.04 O 2-δ Nanopowder and La 1.9 Ba 0.1 Mo 1.85 W 0.15 O 8.95 The nano powder is compounded and sintered to prepare Ce 0.8 (SmLaPrYM) 0.04 O 2-δ The M element is Gd, Dy, Nd, Sc, Lu, Eu or Er, La 1.9 Ba 0.1 Mo 1.85 W 0.15 O 8.95 The amount of nanopowder added is Ce 0.8 (SmLaPrYM) 0.04 O 2-δ 0.05% to 2% of mass.

[0008] A method for preparing a cerium oxide-based composite electrolyte material, firstly using an activated carbon improved sol-gel method to prepare Ce 0.8 (SmLaPrYM) 0.04 O 2-δ Nanopowder, then mixed with La 1.9 Ba 0.1 Mo 1.85 W 0.15 O 8.95 The nanopowders are mixed by mechanical mixing of two powders, and finally sintered to obtain a cerium oxide-based composite electrolyte material.

[0009] As a preferred technical solution of the present invention, the specific steps of the preparation method are as follows:

[0010] ①According to Ce 0.8 (SmLaPrYM)0.04 O 2-δ The required Ce(NO3)3·6H2O, Sm(NO3)3·6H2O, La(NO3)3·6H2O, Pr(NO3)3·6H2O, Y(NO3)3·6H2O and M(NO3)3·6H2O were weighed in a stoichiometric ratio, added to deionized water, stirred and dissolved uniformly to obtain solution A;

[0011] ② Add activated carbon to solution A obtained in step ① and stir to mix evenly;

[0012] ③ Add a chelating agent to the solution obtained in step ②, heat and stir to dissolve, and adjust the pH value of the solution during stirring until a gel is formed;

[0013] ④ Grind the gel after drying, and transfer it into a muffle furnace for heating to obtain powder B;

[0014] ⑤ Mix the powder B obtained in step ④ with an appropriate amount of La 1.9 Ba 0.1 Mo 1.85 W 0.15 O 8.95 The nanopowders are put into a ball milling jar containing zirconium oxide balls, ethanol is added, and the mixture is milled using a planetary ball mill. The mixture is dried and sieved to obtain powder C to be sintered.

[0015] ⑥ Add a binder to the powder C obtained in step ⑤, granulate, screen, and press into a circular green body, which is compacted by cold isostatic pressing; finally, the green body is sintered in an air atmosphere to obtain the cerium oxide-based composite electrolyte material.

[0016] As a further preferred technical solution of the present invention, the preparation method proposed is:

[0017] In step ②, the molar amount of activated carbon is 1.5 to 3.5 times the total molar amount of metal cations in solution A.

[0018] The chelating agent used in step ③ is citric acid, EDTA and ethylene glycol. The molar ratio of citric acid, EDTA, ethylene glycol to the total metal cations in solution A of step ① is 2:1:3:1. After adding the chelating agent, the mixture is stirred and heated at 70-90°C to dissolve. The pH value of the solution is adjusted to 8 by adding ammonia water dropwise until a gel is formed.

[0019] Step ④: After drying the gel, grind it and transfer it into a muffle furnace for heating treatment using a two-step heating method. First, heat it from room temperature to 250°C at 5°C per minute, keep it at 250°C for 2 hours, then heat it from 250°C to 600-800°C at 10°C per minute, and keep it at this temperature for 2-4 hours to obtain powder B.

[0020] Step ⑤ 1.9 Ba 0.1 Mo1.85 W 0.15 O 8.95 The amount of nano powder added is 0.05% to 2% of the mass of powder B. 1.9 Ba 0.1 Mo 1.85 W 0.15 O 8.95 The nanopowders were placed together in a ball mill containing zirconia balls, and ethanol was added so that the mass ratio of powder, zirconia balls and ethanol in the ball mill was 1:4:0.9. The powders were milled in a planetary ball mill at a speed of 150 r / min for 24 hours. After ball milling, the materials were taken out, dried and sieved to obtain powder C to be sintered.

[0021] Step ⑥: Add a 5% polyvinyl alcohol solution as a binder to the powder C obtained in step ⑤ for granulation, wherein the mass of the polyvinyl alcohol solution is 4% of the mass of the powder C. After granulation, the powder is passed through a 100-mesh sieve and pressed into a circular green body, which is compacted by a cold isostatic press at 250 MPa. Finally, the green body is sintered in an air atmosphere. The green body is first heated from room temperature to 500°C at 5°C per minute, kept at 500°C for 2 hours, and then heated from 500°C to 1200°C at 10°C per minute. The mixture is kept warm for 4 to 10 hours and then cooled in the furnace to obtain the cerium oxide-based composite electrolyte material.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] 1. This invention, through optimized high-entropy components and controlled preparation processes, uses a sol-gel method modified with activated carbon to produce pure high-entropy nanopowders with a cubic fluorite structure. This overcomes the difficulty of obtaining pure high-entropy ceramic powders in traditional preparation methods due to uneven mixing and incomplete reactions.

[0024] 2. The composite electrolyte prepared by the present invention has good sintering activity and can achieve material densification at a lower temperature (1200°C). Compared with other preparation methods, its sintering temperature is reduced by 200-400°C. Low-temperature sintering effectively reduces the preparation cost of the material, and is also helpful for the preparation of electrode-loaded electrolyte film components, reducing the co-sintering temperature of the electrode-electrolyte component.

[0025] 3. The composite electrolyte prepared by the present invention has high ionic conductivity and low activation energy in the medium temperature range (600-800°C), which can meet the use requirements of medium temperature SOFCs. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 Example 1 Preparation of Ce 0.8 (SmLaPrYGd) 0.04 O 2-δ XRD spectrum of the powder.

[0027] Figure 2 It is the XRD pattern of the samples prepared in Examples 1 to 4.

[0028] Figure 3 This is the XRD pattern of the sample prepared in Comparative Example 1.

[0029] Figure 4 This is a scanning electron microscope image of the sample prepared in Example 1.

[0030] Figure 5 The relationship between the sample conductivity and temperature of the samples prepared in Examples 1 to 4. DETAILED DESCRIPTION

[0031] Example 1

[0032] A method for preparing a cerium oxide-based composite electrolyte material comprises the following steps:

[0033] ①According to Ce 0.8 (SmLaPrYGd) 0.04 O 2-δ The required Ce(NO3)3·6H2O, Sm(NO3)3·6H2O, La(NO3)3·6H2O, Pr(NO3)3·6H2O, Y(NO3)3·6H2O and Gd(NO3)3·6H2O were weighed in a stoichiometric ratio, added to deionized water, stirred and dissolved uniformly to obtain solution A.

[0034] ② Add activated carbon to the solution obtained in step ① and stir to mix evenly. The molar amount of activated carbon is twice the total molar amount of metal cations in solution A.

[0035] ③ Add citric acid, EDTA, and ethylene glycol to the solution obtained in step ②, with a molar ratio of citric acid, EDTA, and ethylene glycol to the total metal cations in solution A in step ① being 2:1:3:1. Heat to 85°C and stir to dissolve. During stirring, add aqueous ammonia dropwise to adjust the solution to a pH of 8 until a gel forms.

[0036] ④ The gel obtained in step ③ was placed in a forced air drying oven and dried at 80°C, then ground and transferred to a muffle furnace for heating treatment using a two-step heating method: first, the temperature was increased from room temperature to 250°C at 5°C per minute, then kept at 250°C for 2 hours, and then the temperature was increased from 250°C to 600°C at 10°C per minute, and kept at this temperature for 4 hours to obtain powder B.

[0037] ⑤ Combine powder B and La obtained in step ④ 1.9 Ba 0.1 Mo 1.85 W 0.15 O 8.95 The powder is placed in a ball mill containing zirconia balls. 1.9Ba 0.1 Mo 1.85 W 0.15 O 8.95 The mass is 0.05% of the mass of powder B. Ethanol is added so that the weight ratio of powder, zirconium oxide balls and ethanol in the ball mill is 1:4:0.9. The powder is milled in a planetary ball mill at 150 r / min for 24 hours. After ball milling, the material is removed, dried and sieved to obtain powder C to be sintered.

[0038] ⑥ Add a 5% polyvinyl alcohol solution as a binder to the powder C obtained in step ⑤ to form granules. The mass of the polyvinyl alcohol solution is 4% of the mass of the powder C. After granulation, the granules are passed through a 100-mesh sieve and pressed into a circular green body. The green body is compacted by cold isostatic pressing at 250 MPa. Finally, the green body is sintered in an air atmosphere. The green body is first heated from room temperature to 500°C at 5°C per minute, then kept at 500°C for 2 hours, and then heated from 500°C to 1200°C at 10°C per minute. The temperature is kept at this temperature for 6 hours and then cooled in the furnace to produce the cerium oxide-based composite electrolyte material.

[0039] Example 2

[0040] A method for preparing a cerium oxide-based composite electrolyte material comprises the following steps:

[0041] ①According to Ce 0.8 (SmLaPrYDy) 0.04 O 2-δ The required Ce(NO3)3·6H2O, Sm(NO3)3·6H2O, La(NO3)3·6H2O, Pr(NO3)3·6H2O, Y(NO3)3·6H2O and Dy(NO3)3·6H2O were weighed out in the stoichiometric ratio, added into deionized water, stirred and dissolved uniformly to obtain solution A.

[0042] ② Add activated carbon to the solution obtained in step ① and stir to mix evenly. The molar amount of activated carbon is 1.5 times the total molar amount of metal cations in solution A.

[0043] ③ Add citric acid, EDTA, and ethylene glycol to the solution obtained in step ②, with a molar ratio of citric acid, EDTA, and ethylene glycol to the total metal cations in solution A in step ① being 2:1:3:1. Heat to 70°C and stir to dissolve. During stirring, add aqueous ammonia dropwise to adjust the solution to a pH of 8 until a gel forms.

[0044] ④ The gel obtained in step ③ was placed in a forced air drying oven and dried at 90°C, then ground and transferred to a muffle furnace for heating treatment using a two-step heating method: first, the temperature was increased from room temperature to 250°C at 5°C per minute, then kept at 250°C for 2 hours, and then the temperature was increased from 250°C to 700°C at 10°C per minute, and kept at this temperature for 3 hours to obtain powder B.

[0045] ⑤ Combine powder B and La obtained in step ④ 1.9 Ba 0.1 Mo 1.85 W 0.15 O 8.95 The powder is placed in a ball mill containing zirconia balls. 1.9 Ba 0.1 Mo 1.85 W 0.15 O 8.95 The mass is 1% of the mass of powder B. Ethanol is added so that the weight ratio of powder, zirconium oxide balls, and ethanol in the ball mill is 1:4:0.9. The mixture is milled in a planetary ball mill at 150 rpm for 24 hours. After milling, the material is removed, dried, and sieved to obtain powder C to be sintered.

[0046] ⑥ Add a 5% polyvinyl alcohol solution as a binder to the powder C obtained in step ⑤ to form granules. The mass of the polyvinyl alcohol solution is 4% of the mass of the powder C. After granulation, the granules are passed through a 100-mesh sieve and pressed into a circular green body. The green body is compacted by cold isostatic pressing at 250 MPa. Finally, the green body is sintered in an air atmosphere. The green body is first heated from room temperature to 500°C at 5°C per minute, then maintained at 500°C for 2 hours, and then heated from 500°C to 1200°C at 10°C per minute. The green body is sintered at this temperature for 4 hours and then cooled in the furnace to produce the cerium oxide-based composite electrolyte material.

[0047] Example 3

[0048] A method for preparing a cerium oxide-based composite electrolyte material comprises the following steps:

[0049] ①According to Ce 0.8 (SmLaPrYNd) 0.04 O 2-δ The required Ce(NO3)3·6H2O, Sm(NO3)3·6H2O, La(NO3)3·6H2O, Pr(NO3)3·6H2O, Y(NO3)3·6H2O and Nd(NO3)3·6H2O were weighed in the stoichiometric ratio, added to deionized water, stirred and dissolved uniformly to obtain solution A.

[0050] ② Add activated carbon to the solution obtained in step ① and stir to mix evenly. The molar amount of activated carbon is 2.5 times the total molar amount of metal cations in solution A.

[0051] ③ Add citric acid, EDTA, and ethylene glycol to the solution obtained in step ②, with a molar ratio of citric acid, EDTA, and ethylene glycol to the total metal cations in solution A in step ① being 2:1:3:1. Heat to 80°C and stir to dissolve. During stirring, add aqueous ammonia dropwise to adjust the solution to a pH of 8 until a gel forms.

[0052] ④ The gel obtained in step ③ was placed in a forced air drying oven and dried at 85°C, then ground and transferred to a muffle furnace for heating treatment using a two-step heating method: first, the temperature was increased from room temperature to 250°C at 5°C per minute, then kept at 250°C for 2 hours, and then the temperature was increased from 250°C to 750°C at 10°C per minute, and kept at this temperature for 2 hours to obtain powder B.

[0053] ⑤ Combine powder B and La obtained in step ④ 1.9 Ba 0.1 Mo 1.85 W 0.15 O 8.95 The powder is placed in a ball mill containing zirconia balls. 1.9 Ba 0.1 Mo 1.85 W 0.15 O 8.95 The mass is 1.5% of the mass of powder B. Ethanol is added so that the weight ratio of powder, zirconium oxide balls and ethanol in the ball mill is 1:4:0.9. The powder is milled in a planetary ball mill at 150 r / min for 24 hours. After ball milling, the material is removed, dried and sieved to obtain powder C to be sintered.

[0054] ⑥ Add a 5% polyvinyl alcohol solution as a binder to the powder C obtained in step ⑤ to form granules. The mass of the polyvinyl alcohol solution is 4% of the mass of the powder C. After granulation, the granules are passed through a 100-mesh sieve and pressed into a circular green body. The green body is compacted by cold isostatic pressing at 250 MPa. Finally, the green body is sintered in an air atmosphere. The green body is first heated from room temperature to 500°C at 5°C per minute, then maintained at 500°C for 2 hours, and then heated from 500°C to 1200°C at 10°C per minute. The temperature is maintained at this temperature for 8 hours and then cooled in the furnace to produce the cerium oxide-based composite electrolyte material.

[0055] Example 4

[0056] A method for preparing a cerium oxide-based composite electrolyte material comprises the following steps:

[0057] ①According to Ce 0.8 (SmLaPrYEr) 0.04 O 2-δ The required Ce(NO3)3·6H2O, Sm(NO3)3·6H2O, La(NO3)3·6H2O, Pr(NO3)3·6H2O, Y(NO3)3·6H2O and Er(NO3)3·6H2O were weighed in the stoichiometric ratio, added to deionized water, stirred and dissolved uniformly to obtain solution A.

[0058] ② Add activated carbon to the solution obtained in step ① and stir to mix evenly. The molar amount of activated carbon is 3 times the total molar amount of metal cations in solution A.

[0059] ③ Add citric acid, EDTA, and ethylene glycol to the solution obtained in step ②, with a molar ratio of citric acid, EDTA, and ethylene glycol to the total metal cations in solution A in step ① being 2:1:3:1. Heat to 90°C and stir to dissolve. During stirring, add aqueous ammonia dropwise to adjust the solution to a pH of 8 until a gel forms.

[0060] ④ The gel obtained in step ③ was placed in a forced air drying oven and dried at 80°C, then ground and transferred to a muffle furnace for heating treatment using a two-step heating method: first, the temperature was increased from room temperature to 250°C at 5°C per minute, then kept at 250°C for 2 hours, and then the temperature was increased from 250°C to 650°C at 10°C per minute, and kept at this temperature for 3.5 hours to obtain powder B.

[0061] ⑤ Combine powder B and La obtained in step ④ 1.9 Ba 0.1 Mo 1.85 W 0.15 O 8.95 The powder is placed in a ball mill containing zirconia balls. 1.9 Ba 0.1 Mo 1.85 W 0.15 O 8.95 The mass is 1.8% of the mass of powder B. Ethanol is added so that the weight ratio of powder, zirconium oxide balls and ethanol in the ball mill is 1:4:0.9. The powder is milled in a planetary ball mill at 150 r / min for 24 hours. After ball milling, the material is removed, dried and sieved to obtain powder C to be sintered.

[0062] ⑥ Add a 5% polyvinyl alcohol solution as a binder to the powder C obtained in step ⑤ to form granules. The mass of the polyvinyl alcohol solution is 4% of the mass of the powder C. After granulation, the granules are passed through a 100-mesh sieve and pressed into a circular green body. The green body is compacted by cold isostatic pressing at 250 MPa. Finally, the green body is sintered in an air atmosphere. The green body is first heated from room temperature to 500°C at 5°C per minute, then kept at 500°C for 2 hours, and then heated from 500°C to 1200°C at 10°C per minute. The temperature is kept at this temperature for 5 hours and then cooled in the furnace to produce the cerium oxide-based composite electrolyte material.

[0063] Comparative Example 1

[0064] Compared with Example 1, no activated carbon was added during the powder preparation process, and the other steps were the same. The preparation steps are as follows:

[0065] ①According to Ce 0.8 (SmLaPrYGd) 0.04 O 2-δThe required Ce(NO3)3·6H2O, Sm(NO3)3·6H2O, La(NO3)3·6H2O, Pr(NO3)3·6H2O, Y(NO3)3·6H2O and Gd(NO3)3·6H2O were weighed in a stoichiometric ratio, added to deionized water, stirred and dissolved uniformly to obtain solution A.

[0066] ② Add citric acid, EDTA, and ethylene glycol to the solution obtained in step ①, with a molar ratio of citric acid, EDTA, and ethylene glycol to the total metal cations in solution A of step ① being 2:1:3:1. Heat to 85°C and stir to dissolve. During stirring, add aqueous ammonia dropwise to adjust the solution to a pH of 8 until a gel forms.

[0067] ③ The gel obtained in step ② was placed in a forced air drying oven and dried at 80°C, then ground and transferred to a muffle furnace for heating treatment using a two-step heating method: first, the temperature was increased from room temperature to 250°C at 5°C per minute, then kept at 250°C for 2 hours, and then the temperature was increased from 250°C to 600°C at 10°C per minute, and kept at this temperature for 4 hours to obtain powder B.

[0068] ④Powder B and La obtained in step ③ 1.9 Ba 0.1 Mo 1.85 W 0.15 O 8.95 The powder is placed in a ball mill containing zirconia balls. 1.9 Ba 0.1 Mo 1.85 W 0.15 O 8.95 The mass is 0.05% of the mass of powder B. Ethanol is added so that the weight ratio of powder, zirconium oxide balls and ethanol in the ball mill is 1:4:0.9. The powder is milled in a planetary ball mill at 150 r / min for 24 hours. After ball milling, the material is removed, dried and sieved to obtain powder C to be sintered.

[0069] ⑤ Add a 5% polyvinyl alcohol solution as a binder to the powder C obtained in step ④ and granulate it. The mass of the polyvinyl alcohol solution is 4% of the mass of the powder C. After granulation, the powder is passed through a 100-mesh sieve and pressed into a round green body. The green body is compacted by cold isostatic pressing at 250 MPa. Finally, the green body is sintered in an air atmosphere. The green body is first heated from room temperature to 500°C at 5°C per minute, then maintained at 500°C for 2 hours, and then heated from 500°C to 1200°C at 10°C per minute. The green body is sintered at this temperature for 6 hours and then cooled in the furnace to produce the cerium oxide-based composite electrolyte material.

[0070] Comparative Example 2

[0071] Compared with Example 2, without adding La 1.9 Ba 0.1 Mo 1.85 W0.15 O 8.95 The preparation steps are as follows:

[0072] ①According to Ce 0.8 (SmLaPrYDy) 0.04 O 2-δ The required Ce(NO3)3·6H2O, Sm(NO3)3·6H2O, La(NO3)3·6H2O, Pr(NO3)3·6H2O, Y(NO3)3·6H2O and Dy(NO3)3·6H2O were weighed out in the stoichiometric ratio, added into deionized water, stirred and dissolved uniformly to obtain solution A.

[0073] ② Add activated carbon to the solution obtained in step ① and stir to mix evenly. The molar amount of activated carbon is 1.5 times the total molar amount of metal cations in solution A.

[0074] ③ Add citric acid, EDTA, and ethylene glycol to the solution obtained in step ②, with a molar ratio of citric acid, EDTA, and ethylene glycol to the total metal cations in solution A in step ① being 2:1:3:1. Heat to 70°C and stir to dissolve. During stirring, add aqueous ammonia dropwise to adjust the solution to a pH of 8 until a gel forms.

[0075] ④ The gel obtained in step ③ was placed in a forced air drying oven and dried at 90°C, then ground and transferred to a muffle furnace for heating treatment using a two-step heating method: first, the temperature was increased from room temperature to 250°C at 5°C per minute, then kept at 250°C for 2 hours, and then the temperature was increased from 250°C to 700°C at 10°C per minute, and kept at this temperature for 3 hours to obtain powder B.

[0076] ⑤ Place powder B obtained in step ④ into a ball mill containing zirconia balls, add ethanol so that the weight ratio of powder, zirconia balls and ethanol in the ball mill is 1:4:0.9, and use a planetary ball mill to ball mill at a speed of 150 r / min for 24 hours. After ball milling, take out the material, dry it, and sieve it to obtain powder C to be sintered.

[0077] ⑥ Add a 5% polyvinyl alcohol solution as a binder to the powder C obtained in step ⑤ to form granules. The mass of the polyvinyl alcohol solution is 4% of the mass of the powder C. After granulation, the granules are passed through a 100-mesh sieve and pressed into round green bodies. The green bodies are compacted using a cold isostatic press at 250 MPa. Finally, the green bodies are sintered in an air atmosphere. The green bodies are first heated from room temperature to 500°C at 5°C per minute, maintained at 500°C for 2 hours, and then heated from 500°C to 1200°C at 10°C per minute. The temperature is maintained at this temperature for 4 hours and then cooled in the furnace to produce the cerium oxide-based electrolyte material.

[0078] Performance characterization of electrolyte materials prepared in Examples 1-4 and Comparative Examples 1-2:

[0079] 1. XRD test

[0080] Different substances have specific atomic species, atomic arrangements, and lattice parameters. Under the action of X-rays, different crystal planes diffract individually, producing unique diffraction patterns. X-ray powder diffraction is used to determine the structure of a powder.

[0081] Figure 1 Example 1 Preparation of Ce 0.8 (SmLaPrYGd) 0.04 O 2-δ The XRD spectrum of the powder Figure 1 It can be seen that Ce 0.8 (SmLaPrYGd) 0.04 O 2-δ The XRD pattern of the powder corresponds well to the diffraction peak of CeO2 (JCPDS card 34-0394) of cubic fluorite in the standard PDF card, and no other impurities appear, indicating that Sm 3+ 、La 3+ 、Pr 3+ 、Y 3+ 、Gd 3+ It is a good substitute for Ce in the lattice 4+ At the same time, it can be seen that the diffraction peaks of the spectrum are significantly broadened, indicating that the high entropy powder has fine grains. According to the Scherre formula, Ce 0.8 (SmLaPrYGd) 0.04 O 2-δ The average grain size of the powder is 15 nm.

[0082] Figure 2 The XRD patterns of the samples prepared in Examples 1 to 4 and sintered at 1200°C are shown in Figure 2. Figure 2 It can be seen that the XRD pattern of the sample is consistent with the standard spectrum of cubic fluorite CeO2 JCPDS card 34-0394, and no other phase diffraction peaks appear, indicating that trace amounts of La 1.9 Ba 0.1 Mo 1.85 W 0.15 O 8.95 With a lot of Ce 0.8 (SmLaPrYM) 0.04 O 2-δ After mixed sintering, La 1.9 Ba 0.1 Mo 1.85 W 0.15 O 8.95 Well integrated into the CeO2 matrix. In addition, Figure 2It can be seen that the diffraction peaks of all samples are sharp, the intensity is relatively large, and the half-peak width is narrow, indicating that the crystallization of the samples after sintering at 1200℃ is better.

[0083] Figure 3 This is the XRD pattern of the sample prepared in Comparative Example 1 after sintering at 1200°C. Figure 3 As can be seen, the sample exhibits a distinct impurity phase. This demonstrates the difficulty of obtaining pure high-entropy ceramic materials with a cubic fluorite structure using conventional sol-gel methods. However, the present invention improves the sol-gel method by adding activated carbon, effectively resolving the problem of impurity phases in high-entropy materials, which is often difficult to evenly mix (disperse) due to the large number of components and incomplete reactions.

[0084] 2. Sintering performance

[0085] Figure 4 This is a scanning electron microscope image of the sample prepared in Example 1 after sintering at 1200°C. Figure 4 It can be seen that the surface morphology of the sintered sample is clear, the grains are tightly bonded and there are almost no pores, indicating that a dense sintered body can be obtained by sintering at 1200℃.

[0086] The relative density of the sintered samples was measured by the Archimedean method (as shown in Table 1). The relative density of the samples prepared in Examples 1 to 4 after sintering at a temperature of 1200°C was higher than 96%, which met the requirements for use in SOFCs. 1.9 Ba 0.1 Mo 1.85 W 0.15 O 8.95 Composite Ce 0.8 (SmLaPrYDy) 0.04 O 2-δ (Comparative Example 2) The relative density after sintering at 1200°C was only 89.9%, indicating that compounding is beneficial to the densification of the sample.

[0087] Table 1: Properties of samples sintered at 1200℃

[0088]

[0089] As can be seen from Table 1, the high-entropy cerium oxide-based composite electrolyte material prepared by the present invention has good sintering activity and can achieve material densification at a lower temperature (1200°C). Compared with other methods, its sintering temperature is reduced by 200-400°C. Low-temperature sintering effectively reduces the preparation cost of the material, and is also helpful for the preparation of supported electrolyte films and reduces the co-sintering temperature of the electrode-electrolyte.

[0090] 3. The two-electrode method was used to measure the AC impedance spectrum of the sample. Before the test, the front and back of the polished sintered disc were wrapped with silver paste and kept at 800°C for 10 minutes to ensure good contact between the electrode and the electrolyte. The SI-1260 impedance analyzer (0.1Hz~1.0MHz) was used to measure the AC impedance of the sample. The ZSimpwin software was used to analyze the AC impedance spectrum and read the coordinates of the intersection of the semicircular arc at the medium and high frequency end and the real axis (Z') to obtain the total resistance R. The conductivity σ of the sample can be obtained by the following formula:

[0091]

[0092] Where: D is the sample thickness, R is the total resistance, and S is the cross-sectional area of ​​the sample.

[0093] Figure 5 The graph is the relationship between the conductivity and temperature of the sintered samples prepared in Examples 1 to 4. Figure 5 It can be seen that the high-entropy cerium oxide-based composite electrolyte prepared by the present invention has a high ionic conductivity in the medium temperature range (600-800°C), and the ionic conductivity value increases with increasing temperature. At a test temperature of 800°C, the conductivity reaches 0.031, 0.037, 0.044 and 0.034 S / cm, respectively (as shown in Table 1), which can meet the use requirements of medium-temperature SOFCs.

[0094] At the same time, the conductivity of the samples prepared in Comparative Examples 1 and 2 is relatively low, and the conductivity is only 0.019 and 0.017 S / cm at a test temperature of 800°C (as shown in Table 1). The conductivity of the sample prepared in Comparative Example 1 is relatively low when the relative density is similar to that of Example 1. This is because the impurity phase is a poor conductor of oxygen ions; the conductivity of the sample in Comparative Example 2 is not high because the high-conductivity low-melting-point phase La is not added. 1.9 Ba 0.1 Mo 1.85 W 0.15 O 8.95 The composite material is not sintered sufficiently and the density is not high enough.

[0095] Through analysis, we know that the high conductivity factors of high entropy cerium oxide based composite electrolyte materials are mainly: 1. Low melting point La 1.9 Ba 0.1 Mo 1.85 W 0.15 O 8.95 The liquid phase sintering mechanism effectively promotes the sintering and mass transfer of the material, so that the grains grow completely, the material has a high density, low porosity, a small interface area between grains, and reduced interface resistance; 2. Ce 0.8 (SmLaPrYM) 0.04 O 2-δ and La 1.9 Ba0.1 Mo 1.85 W 0.15 O 8.95 The lattice constants are quite different. When the two are composite-sintered, grain boundary movement, grain rearrangement and lattice distortion occur at the grain boundaries, resulting in a large number of defects. The presence of defects increases the migration ability of oxygen ions and oxygen vacancies, resulting in a significant improvement in the conductivity of the material.

[0096] The above content is merely an example and explanation of the concept of the present invention. Those skilled in the art may make various modifications or additions to the described specific embodiments or replace them in a similar manner. As long as they do not deviate from the concept of the invention or exceed the scope defined by the claims, they should all fall within the scope of protection of the present invention.

Claims

1. A method for preparing a cerium oxide-based composite electrolyte material, characterized in that: By Ce 0.8 (SmLaPrYM) 0.04 O 2-δ Nanopowder and La 1.9 Ba 0.1 Mo 1.85 W 0.15 O 8.95 The nano powder is compounded and sintered to prepare Ce 0.8 (SmLaPrYM) 0.04 O 2-δ The M element is Gd, Dy, Nd, Sc, Lu, Eu or Er, La 1.9 Ba 0.1 Mo 1.85 W 0.15 O 8.95 The amount of nanopowder added is Ce 0.8 (SmLaPrYM) 0.04 O 2-δ 0.05% to 2% of the mass; the specific steps are as follows: ①According to Ce 0.8 (SmLaPrYM) 0.04 O 2-δ The required Ce(NO3)3·6H2O, Sm(NO3)3·6H2O, La(NO3)3·6H2O, Pr(NO3)3·6H2O, Y(NO3)3·6H2O and M(NO3)3·6H2O were weighed in a stoichiometric ratio, added to deionized water, stirred and dissolved uniformly to obtain solution A; ② Add activated carbon to solution A obtained in step ① and stir to mix evenly; ③ Add a chelating agent to the solution obtained in step ②, heat and stir to dissolve, and adjust the pH value of the solution during stirring until a gel is formed; ④ Grind the gel after drying, and transfer it into a muffle furnace for heating to obtain powder B; ⑤ Mix the powder B obtained in step ④ with an appropriate amount of La 1.9 Ba 0.1 Mo 1.85 W 0.15 O 8.95 The nanopowders are put into a ball milling jar containing zirconium oxide balls, ethanol is added, and the mixture is milled using a planetary ball mill. The mixture is dried and sieved to obtain powder C to be sintered. ⑥ Add a binder to the powder C obtained in step ⑤, granulate, screen, and press into a circular green body, which is compacted by cold isostatic pressing; finally, the green body is sintered in an air atmosphere to obtain the cerium oxide-based composite electrolyte material.

2. The preparation method according to claim 1, wherein In step ②, the molar amount of activated carbon is 1.5 to 3.5 times the total molar amount of metal cations in solution A.

3. The preparation method according to claim 1, wherein The chelating agent used in step ③ is citric acid, EDTA and ethylene glycol. The molar ratio of citric acid, EDTA, ethylene glycol to the total metal cations in solution A of step ① is 2:1:3:

1. After adding the chelating agent, the mixture is stirred and heated at 70-90°C to dissolve. The pH value of the solution is adjusted to 8 by adding ammonia water dropwise until a gel is formed.

4. The preparation method according to claim 1, wherein Step ④: After drying the gel, grind it and transfer it into a muffle furnace for heating treatment using a two-step heating method. First, heat it from room temperature to 250°C at 5°C per minute, keep it at 250°C for 2 hours, then heat it from 250°C to 600-800°C at 10°C per minute, and keep it at this temperature for 2-4 hours to obtain powder B.

5. The preparation method according to claim 1, wherein Step ⑤ 1.9 Ba 0.1 Mo 1.85 W 0.15 O 8.95 The amount of nanopowder added is 0.05% to 2% of the mass of powder B.

6. The preparation method according to claim 1, wherein Step 5: Powder B and La obtained in step 4 1.9 Ba 0.1 Mo 1.85 W 0.15 O 8.95 The nanopowders were placed together in a ball mill containing zirconia balls, and ethanol was added so that the mass ratio of powder, zirconia balls and ethanol in the ball mill was 1:4:0.

9. The powders were milled in a planetary ball mill at a speed of 150 r / min for 24 hours. After ball milling, the materials were taken out, dried and sieved to obtain powder C to be sintered.

7. The preparation method according to claim 1, wherein Step ⑥ Add a polyvinyl alcohol solution with a mass concentration of 5% as a binder to the powder C obtained in step ⑤ for granulation, wherein the mass of the polyvinyl alcohol solution is 4% of the mass of the powder C. After granulation, the powder is passed through a 100-mesh sieve and pressed into a circular green body, and compacted by a cold isostatic pressing at 250 MPa; finally, the green body is sintered in an air atmosphere, and the green body is first heated from room temperature to 500°C at 5°C per minute, and then kept at 500°C for 2 hours, and then heated from 500°C to 1200°C at 10°C per minute, and sintered for 4 to 10 hours, and cooled with the furnace to obtain the cerium oxide-based composite electrolyte material.

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