Low-temperature ceramic fuel cell electrolyte material as well as preparation method and application thereof
By using fluorite structure alumina or cerium-doped fluorite structure alumina materials and combining with dry pressure method to prepare ceramic fuel cells, the problems of insufficient ionic conductivity and stability of electrolyte materials at low temperatures are solved, and efficient electrochemical performance and low-cost commercial applications are achieved.
Patent Information
- Application Number
- CN202410289946.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-03-14
- Publication Date
- 2025-07-25
AI Technical Summary
The electrolyte materials of existing low-temperature ceramic fuel cells can achieve ideal ionic conductivity at high temperatures, resulting in slow commercialization progress and unstable traditional materials in reducing atmospheres, which can easily cause electrochemical leakage and power loss.
The electrolyte is prepared by grinding and mixing, one-step combustion/sintering method, wet chemistry method or direct sintering method, and a ceramic fuel cell is constructed in combination with dry pressure method to achieve high ionic conductivity and stability at low temperatures.
At low temperature, the ionic conductivity of 0.1S/cm and the output power of 600~1150mW/cm2 are achieved. The battery can work continuously at low temperatures, avoiding the high-temperature sintering process, reducing the preparation cost, and improving the stability and electrochemical performance of the battery.
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Figure CN120376704A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to an electrolyte material for a low-temperature (300-500 °C) ceramic fuel cell, and also relates to a preparation method of the above electrolyte material and a ceramic fuel cell prepared based on the electrolyte material. Background Art
[0002] A fuel cell is an energy conversion device that directly converts the chemical energy in fuel into electrical energy, and has the characteristics of cleanness and high efficiency. The electrolyte membrane is the core component of all fuel cell devices. The main representative materials of SOFC electrolytes are yttria-stabilized zirconia (YSZ) and samarium-doped ceria (SDC). However, they both face challenges in commercial application as electrolyte materials.
[0003] Traditional solid oxide fuel cells (SOFCs) all use a fluorite-type structure formed by yttria-stabilized zirconia (YSZ) with oxygen ion conduction. Since YSZ can reach an ideal ionic conductivity >0.1 S / cm only at a high temperature of about 1000 °C, for decades, the high-temperature operation requirements and high cost of SOFCs have delayed the commercialization progress of SOFCs. And for yttria-stabilized zirconia, the doping amount of yttrium in zirconia must be limited. For example, zirconia doped with less than 10 mol% yttrium can obtain a fluorite structure suitable for the SOFC operating temperature. Moreover, only by + replacing Zr 4+ with Y in the formed fluorite structure can oxygen vacancies be generated to produce effective oxygen ion conduction. Due to the high-temperature limitation, SOFCs have always faced challenges in commercialization.
[0004] People have tried many other materials that can replace YSZ to reduce the operating temperature of SOFCs. For example, by doping various low-valence cations into the ceria fluorite structure, typically doping 10-20 mol% of Sm 3+ or Gd 3+ , a fluorite structure containing oxygen vacancies can be formed to produce effective oxygen ion transport, and the conductivity that YSZ can obtain at 1000 °C can be achieved at 800 °C, and the operating temperature is reduced by 200 °C compared with YSZ. However, it still belongs to a high-temperature fluorite-type electrolyte material. Coupled with the instability of ceria in the hydrogen (reduction atmosphere of the fuel cell) atmosphere, Ce 4+ is reduced to Ce 3+ , accompanied by obvious electronic conduction, which is likely to cause electrochemical leakage and power loss of the fuel cell. Therefore, the ceria fluorite structure doped with cations has not replaced YSZ for a long time.
[0005] The key to reducing the operating temperature of fuel cells is to develop new electrolyte materials. In order to obtain an electrolyte material with excellent performance and stability at low temperatures (<600 °C) and promote the commercialization of ceramic fuel cells, it is urgent to develop new electrolyte materials at present. Summary of the Invention
[0006] Object of the Invention: The object of the present invention is to provide an electrolyte material for a low-temperature (300 - 500 °C) ceramic fuel cell, with an ionic conductivity of 0.1 S / cm at low temperature; another object of the present invention is to provide a preparation method of the above electrolyte material and its application in constructing a ceramic fuel cell. The ceramic fuel cell constructed based on the electrolyte material of the present invention can achieve good electrochemical performance and stable power output at low temperature.
[0007] Technical Solution: The electrolyte material for the low-temperature ceramic fuel cell described in the present invention is an alumina material with a fluorite structure or a cerium-doped alumina material with a fluorite structure.
[0008] When the electrolyte material is an alumina material with a fluorite structure, it is prepared by the following method: specifically,
[0009] Grinding and Mixing + One-step Combustion / Sintering Method: Mix aluminum nitrate nonahydrate or aluminum hydroxide, an ammonium salt, and urea evenly in a molar ratio of 1 - 5:1 - 3:1 - 3, place them in a muffle furnace, heat to 600 - 800 °C to gradually melt the raw materials; then continue to keep the temperature at 600 - 800 °C in the muffle furnace for heat preservation, an auto-combustion reaction occurs, and after cooling to room temperature, an alumina material with a fluorite structure is obtained.
[0010] When the electrolyte material is an alumina material with a fluorite structure, it is prepared by the following method: specifically,
[0011] Wet Chemical Method: Mix aluminum nitrate nonahydrate or aluminum hydroxide, an ammonium salt, urea, and water evenly to make the concentration of aluminum nitrate or aluminum hydroxide in the system 0.5 - 5 M. Place the mixed material in an oven and dry it at 120 °C for 8 - 12 hours to form an alumina precursor; transfer the alumina precursor to a muffle furnace, heat to 600 - 800 °C and keep it at a constant temperature for sintering for 4 - 12 hours to remove residual impurities, and obtain an alumina material with a fluorite structure.
[0012] When the electrolyte material is an alumina material with a fluorite structure, it is prepared by the following method: specifically,
[0013] Wet Chemical Method: Mix aluminum nitrate nonahydrate and water to make the concentration of aluminum nitrate in the solution 0.5 - 5 M; add citric acid powder to the solution at a rate of 5 - 10 g of aluminum nitrate nonahydrate plus 0.5 - 2.0 g of granular citric acid. Place the mixed material in an oven and dry it at 120 °C for 3 - 12 hours to form an alumina precursor; transfer the alumina precursor to a muffle furnace, heat to 600 - 800 °C and keep it at a constant temperature for sintering for 4 - 12 hours to remove residual impurities, and obtain an alumina material with a fluorite structure.
[0014] When the electrolyte material is an alumina material with a fluorite structure, it is prepared by the following method, specifically:
[0015] Direct sintering method: Without adding any combustion aids, put aluminum nitrate nonahydrate into a muffle furnace, control the heating rate at 10 - 20 °C / min and heat up to 600 - 800 °C to decompose the aluminum nitrate, keep it warm and sinter for 4 - 12 hours at 600 - 800 °C, and then cool it naturally or take it out from the muffle furnace for standby.
[0016] When the electrolyte material is a cerium-doped alumina material with a fluorite structure, it is prepared by the following method, specifically:
[0017] Mix aluminum nitrate nonahydrate and cerium nitrate hexahydrate in a molar ratio of 4 - 9:1 - 3 to obtain a mixture; mix the mixture, citric acid and water evenly, add 0.5 - 2.0 g of granular citric acid for every 5 - 10 g of the mixture to make the concentration of aluminum nitrate in the system 0.5 - 5 M, place the mixed materials in an oven, dry at 120 °C for 5 - 12 hours to form an alumina precursor; transfer the alumina precursor to a muffle furnace, heat it to 600 - 800 °C and keep it at a constant temperature for sintering for 4 - 12 hours to remove the residual impurities and obtain a cerium-doped alumina material with a fluorite structure.
[0018] When the electrolyte material is a cerium-doped alumina material with a fluorite structure, it is prepared by the following method, specifically:
[0019] Mix aluminum nitrate nonahydrate and cerium nitrate hexahydrate in a molar ratio of 4 - 9:1 - 3 to obtain a mixture; without adding any combustion aids, put the mixture into a muffle furnace, control the heating rate at 6 - 10 °C / min and heat up to 750 - 800 °C to decompose the aluminum nitrate and cerium nitrate, keep it warm and sinter for 6 - 10 hours at 750 - 800 °C, and then cool it naturally or take it out from the muffle furnace for standby.
[0020] The application of the above electrolyte material in constructing a ceramic fuel cell is as follows: The ceramic fuel cell uses an alumina powder with a fluorite structure or a cerium-doped alumina powder with a fluorite structure as the electrolyte material, and uses NCAL as the symmetric electrode of the fuel cell; fill the NCAL electrode, the alumina powder with a fluorite structure or the cerium-doped alumina powder with a fluorite structure, and NCAL into a steel mold with a diameter of 13 mm in sequence, and press it under a pressure of 6 - 12 MP to obtain an NCAL / electrolyte / NCAL structure battery.
[0021] Drop 5 mL of terpineol into 20 g of NCAL, then add 1 g of PVDF binder and grind them together to obtain a slurry; use a brush pen to apply the NCAL (Ni 0.8 Co 0.15 Al 0.05 LiO2-δ )The slurry is evenly coated on nickel foam with an effective area of 15 cm 2 and a thickness of 1 - 2 mm; Weigh 0.1 - 0.2 g of alumina-based electrolyte material, and successively place the NCAL electrode, electrolyte powder, and NCAL electrode in a pressing mold, and press for 1 min under a pressure of 6 - 12 MP to obtain a wafer fuel cell (NCAL / fluorite alumina or cerium-doped alumina / NCAL).
[0022] The NCAL / fluorite alumina / NCAL battery prepared by the dry pressing method of the present invention has obtained an ionic conductivity exceeding 0.1 S / cm and an output power of 600 - 1150 mW / cm 2 at an operating temperature of 400 - 520 °C, and the battery can continuously work at this temperature.
[0023] Advantages: Compared with the prior art, the present invention has the following remarkable effects: (1) The electrolyte material of the present invention conducts mixed oxygen ions - protons at low temperatures and has the characteristic of low activation energy, so an ionic conductivity of 0.1 S / cm can be obtained at low temperatures. (2) The ceramic fuel cell prepared based on the electrolyte material of the present invention is tested for performance within the temperature range of 400 - 520 °C, and the output power of the battery is 600 - 1150 mW / cm 2 . (3) The present invention can prepare alumina with a fluorite structure and cerium-doped alumina with a fluorite structure, which have the characteristic of a high natural oxygen vacancy in the structure. Compared with traditional YSZ and 20% samarium-doped ceria electrolyte materials, the oxygen vacancy is 5 - 10 times higher. And fluorite alumina has a large number of oxygen vacancies generated during its own structure formation process, while traditional YSZ and SDC fluorite structure electrolytes must be doped to obtain a considerable ionic conductivity. Therefore, the ceramic fuel cell prepared based on the electrolyte material of the present invention has good stability. At an operating temperature of 440 °C and a power density of 110 mW / cm 2 , the average operating voltage is 0.92 V, and it can stably operate for 100 h. (4) The method for preparing the battery in the present invention is a simple and operable dry pressing method, which avoids the high-temperature sintering process of traditional ceramic fuel cells and further reduces its preparation cost. Description of the Drawings
[0024] Figure 1 (a) XRD pattern of the amorphous alumina sample; Figure 1 (b) XRD patterns of the fluorite structure alumina prepared in Example 3 of the present invention and the cerium-doped fluorite structure alumina prepared in Examples 5 - 7; Introducing high-valent Ce 4+ doping makes Al2O3 have a fluorite structure, where 10Ce, 20Ce, and 30Ce respectively refer to the doping amount of cerium being 10 wt%, 20 wt%, and 30 wt%;
[0025] Figure 2 High-resolution TEM image of cerium-doped fluorite-structured alumina prepared in Example 5;
[0026] Figure 3 (a) Raman spectra of fluorite-structured alumina prepared in Example 4 of the present invention and cerium-doped fluorite-structured alumina prepared in Examples 5-7; Figure 3 (b) Characteristic spectra of fluorite alumina and cerium-doped alumina showing the same fluorite structure as cerium oxide;
[0027] Figure 4 (a) Output power results of a low-temperature ceramic fuel cell based on cerium-doped fluorite-structured alumina prepared in Example 7 at 370-520 °C; Figure 4 (b) Comparison (Arrhenius curve) of the electrolyte material prepared in Example 7 with traditional YSZ and GDC / SDC; Figure 4 (c) Electrical performance (impedance spectrum) diagram of the fuel cell in (a) at 400-520 °C;
[0028] Figure 5 Performance comparison of ceramic fuel cells based on fluorite-structured alumina prepared in Example 3 and other commercial aluminas at 500 °C;
[0029] Figure 6 Ceramic fuel cell based on cerium-doped fluorite-structured alumina prepared in Example 7 at 440 °C, 110 mW / cm 2 Stable operation at current density;
[0030] Figure 7 Application process of a fuel cell based on cerium (20 wt%)-doped fluorite-structured alumina prepared in Example 5. Detailed implementation manners
[0031] Example 1
[0032] When the electrolyte material is a fluorite-structured alumina material, it is prepared by the following method: using aluminum nitrate nonahydrate as the raw material and adopting the grinding mixing and one-step combustion / sintering method:
[0033] (1) Weigh 0.03 moles of aluminum nitrate nonahydrate crystal powder, add 0.02 moles of NH4OH (ammonium hydroxide) and 0.02 moles of urea, mix and grind thoroughly to obtain a mixture;
[0034] (2) Place the mixture in a muffle furnace and heat it to 750 °C at a heating rate of 10 °C / min. During the heating process, the raw materials gradually melt, undergoing a natural heating and decomposition process. Then, keep it sintered at 750 °C for 4 h, and cool it in the furnace or directly take it to room temperature from the sintering temperature to obtain alumina powder with a fluorite structure.
[0035] Example 2
[0036] When the electrolyte material is alumina material with a fluorite structure, it is prepared by the following method. Specifically: using aluminum nitrate nonahydrate as the raw material and the wet chemical method:
[0037] (1) Weigh 0.1 mole of aluminum nitrate nonahydrate crystal powder, dissolve it in pure water to form an aluminum nitrate solution with a concentration of 0.5 M, then add 0.1 mole of NH4OH and 0.1 mole of urea, stir evenly, and dry it in an oven at 120 °C for 10 hours;
[0038] (2) Place the dried product in a muffle furnace and heat it to 750 °C at a heating rate of 10 °C / min. The heating process undergoes a heating and decomposition process, and then keep it sintered at 750 °C for 4 h, cool it in the furnace or directly take it to room temperature to obtain alumina powder with a fluorite structure.
[0039] Example 3
[0040] When the electrolyte material is alumina material with a fluorite structure, it is prepared by the following method. Specifically: using aluminum nitrate nonahydrate as the raw material and the wet chemical method:
[0041] (1) Weigh 0.1 mole of aluminum nitrate nonahydrate crystal powder, dissolve it in pure water to form an aluminum nitrate solution with a concentration of 0.5 M, then add 5 g of citric acid powder, stir evenly, and dry it in an oven at 120 °C for 5 hours;
[0042] (2) Place the dried product in a muffle furnace and heat it to 750 °C at a heating rate of 10 °C / min. The heating process undergoes a heating and decomposition process, and then keep it sintered at 750 °C for 4 h, cool it in the furnace or directly take it to room temperature to obtain alumina powder with a fluorite structure.
[0043] Example 4
[0044] When the electrolyte material is alumina material with a fluorite structure, it is prepared by the following method. Specifically: using aluminum nitrate nonahydrate as the raw material and the direct decomposition method:
[0045] Weigh 0.1 mole of aluminum nitrate nonahydrate crystal powder without any treatment. Place it directly in a muffle furnace and heat it to 750 °C at a heating rate of 10 °C / min. The heating process undergoes heating and decomposition processes. Then, keep it sintered at 750 °C for 4 h, and cool it with the furnace or directly take it out to room temperature to obtain alumina powder with a fluorite structure.
[0046] Example 5
[0047] When the electrolyte material is cerium-doped alumina material with a fluorite structure, it is prepared by the following method: Using aluminum nitrate nonahydrate and cerium nitrate hexahydrate as raw materials, use the wet chemical method to synthesize cerium-doped alumina material with a fluorite structure:
[0048] (1) Weigh 0.08 mole of aluminum nitrate nonahydrate and 0.02 mole of cerium nitrate hexahydrate crystal powder, and prepare them into a 0.5 M concentration with pure water (referring to the concentration of aluminum nitrate being 0.5 M). Then add 6 g of citric acid powder to it, stir evenly, and dry it in an oven at 120 °C for 5 hours;
[0049] (2) Place the dried product in a muffle furnace and heat it to 750 °C at a heating rate of 10 °C / min. The heating process undergoes heating and decomposition processes. Then, keep it sintered at 750 °C for 4 h, and cool it with the furnace or directly take it out to room temperature to obtain cerium-doped alumina powder with a fluorite structure, where the cerium doping amount is 20 wt% (Al:Ce = 4:1).
[0050] Example 6
[0051] When the electrolyte material is cerium-doped alumina material with a fluorite structure, it is prepared by the following method: Using aluminum nitrate nonahydrate and cerium nitrate hexahydrate as raw materials, use the solid-phase sintering method to synthesize cerium-doped alumina material with a fluorite structure:
[0052] Weigh 0.09 mole of aluminum nitrate nonahydrate and 0.01 mole of cerium nitrate hexahydrate crystal powder, grind and mix them evenly. Place the mixture in a muffle furnace and heat it to 800 °C at a heating rate of 6 °C / min. The heating process undergoes heating and decomposition processes. Then, keep it sintered at 800 °C for 6 h and then cool it with the furnace to obtain cerium-doped alumina powder with a fluorite structure, where the cerium doping amount is 10 wt% (Al:Ce = 9:1).
[0053] Example 7
[0054] When the electrolyte material is cerium-doped alumina material with a fluorite structure, it is prepared by the following method. Specifically: Mix aluminum nitrate nonahydrate and cerium nitrate hexahydrate in a molar ratio of 7:3 to obtain a mixture; Mix the mixture, citric acid and water evenly. Add 0.5 - 2.0 grams of granular citric acid per 5 - 10 grams of the mixture to make the concentration of aluminum nitrate in the system 0.5M, obtaining a mixed material; Place the mixed material in an oven and dry it at 120°C for 5 - 12 hours to form an alumina precursor; Transfer the alumina precursor to a muffle furnace, heat it to 600 - 800°C and sinter it at a constant temperature for 4 - 12 hours to remove residual impurities, obtaining cerium-doped alumina powder with a fluorite structure, where the cerium doping amount is 30wt% (Al:Ce = 7:3).
[0055] Both the alumina and cerium-doped alumina prepared in the present invention have a fluorite structure, and their chemical formula can be written as AlO2-d (d is equal to or close to 0.5). Due to the lack of a large amount of lattice oxygen (25%), the XRD pattern of pure alumina fluorite has a strong amorphous background, as shown in Figure 1 b, and the introduction of high-valent Ce 4+ doping makes the amorphous background disappear, and the surface lattice order forms a perfect fluorite structure. As a comparison, the lattice oxygen deficiency of 10% GDC-doped ceria is only 2.5%, that is, the oxygen vacancy corresponding to its structural unit is only 0.2, while that of fluorite-structured alumina is as high as 2, which is 10 times that of it.
[0056] Figure 2 It is the high-resolution electron microscope image of the cerium-doped fluorite-structured alumina prepared in Example 5; Different crystal plane images of the fluorite lattice in the figure are calibrated, further microscopically proving the symmetry of the fluorite structure of the synthesized material.
[0057] Among them, Figure 2 a, 2b, 2c are the micro-morphologies, the micro-morphologies under different conditions, Figure 2 a is 200nm, Figure 2 b is 100nm, Figure 2 c is 10nm; Figure 2 d, 2e, 2f are 5nm, inside the yellow circles in the figure, the stripes are regular and are selected to measure the lattice size, such as Figure 2 0.28nm, 0.27nm in d, Figure 2 0.272nm, 0.30nm in e; and Figure 2 0.25nm in f. By comparing with the standard unit cell parameter diagram, it is determined that it is a fluorite structure; Figure 2 g, 2h, 2i, 2j are element analyses. g is the dark field image of the sample. By performing element dotting on the dark field image, we can obtain Figure 2h, 2i, 2j. The distributions of Al, Ce, and O elements in the sample can be seen respectively from 2h, 2i, 2j.
[0058] Figure 3 Furthermore, Raman was used to determine its structural symmetry. It was found that fluorite-structured alumina and cerium-doped fluorite-structured alumina showed the characteristic spectrum of the fluorite structure, the F2g mode, which is a specific vibration mode or phonon mode within the lattice of the fluorite structure, similar to that of cerium oxide. As the Ce doping amount increased, the Raman peak shifted to a higher wavenumber by several cm -1 , which means that there were subtle changes in the local environment around the oxygen atoms in the AlO2-d fluorite structure. Replacing Al 4+ ions with Ce 3+ ions might strengthen the bonding within the alumina lattice, resulting in the shift of the F2g Raman mode to a higher wavenumber. This is the result of Ce 4+ ions carrying a larger ionic radius and a higher positive charge, which affected the interaction with the surrounding oxygen atoms and thus strengthened the bonding within the lattice.
[0059] Figure 4 (a) Output power results of the cerium-doped fluorite-structured alumina-based low-temperature ceramic fuel cell prepared according to Example 7 at 370 - 520 °C; the ionic conductivity reached 0.1 S / cm at 520 °C, and the output power of the fuel cell was 1150 mW / cm 2 .
[0060] Figure 4 (b) Comparison with traditional YSZ and GDC / SDC (Arrhenius curve). The flatter the curve, the lower the activation energy. The comparison (Arrhenius curve) of the cerium-doped fluorite-structured alumina electrolyte prepared according to Example 7 with traditional YSZ and GDC / SDC shows that the ionic activation energy of the cerium-doped fluorite-structured alumina electrolyte is 0.25 eV, while that of the traditional fluorite electrolyte is above 0.7 eV; and the ionic conductivity is 1 - 2 orders of magnitude higher than that of traditional YSZ and GDC / SDC, and the ionic migration activation energy is also significantly reduced.
[0061] Figure 5 shows the performance comparison at 500 °C of the fluorite-structured alumina-based ceramic fuel cell prepared according to Example 3 and other commercial aluminas; the electrochemical performance of the ceramic fuel cell based on the electrolyte of the present invention is several times higher than that of the ceramic fuel cell based on commercial alumina. The fluorite alumina fuel cell obtained 830 mW / cm 2 at 500 °C, while that of alpha-alumina is about 300 mW / cm 2 , and that of gamma-alumina only reaches less than 100 mW / cm 2In addition, the open-circuit voltage of commercial alumina electrolyte fuel cells is lower than that of fluorite alumina electrolyte fuel cells.
[0062] Figure 6 The ceramic fuel cell based on the cerium-doped fluorite-structured alumina prepared in Example 7 has stable operation at 440 °C and a current density of 110 mW / cm 2 ; the voltage curve of the fuel cell operating at 440 °C and a current density of 110 mW / cm 2 shows that the operating voltage is 0.92 V and the open-circuit voltage of the battery is maintained at 1.1 V, indicating that the battery has not short-circuited or leaked air, demonstrating the feasibility of preparing the battery by the dry pressing method; the battery can operate stably for 100 h at a power density of 110 mW / cm 2 and an average operating voltage of 0.92 V.
[0063] Figure 7 The application process of the fuel cell based on the cerium(20 wt%)-doped fluorite-structured alumina prepared in Example 5 is as follows: the operation of the fuel cell. Such a dry-pressed alumina-based electrolyte fuel cell (with an active area of 0.64 cm 2 ) can operate at 420 °C for several hours (20 hours) with two parallel fans. The net power of each fan is about 0.2 watts. The photo of the fuel cell after operation is as shown in Figure 7 b. It can be seen that the battery still maintains its shape well, thus showing good electrochemical and thermal stability and mechanical strength without any cracks.
Claims
1. An electrolyte material for a low-temperature ceramic fuel cell, characterized in that: The electrolyte material is an alumina material with a fluorite structure or a cerium-doped alumina material with a fluorite structure.
2. The electrolyte material for a low-temperature ceramic fuel cell according to claim 1, characterized in that: When the electrolyte material is an alumina material with a fluorite structure, it is prepared by the following method. Specifically: Mix aluminum nitrate nonahydrate or aluminum hydroxide, an ammonium salt, and urea evenly at a molar ratio of 1-5:1-3:1-3, place them in a muffle furnace, heat to 600-800 °C to gradually melt the raw materials; then continue to keep the temperature at 600-800 °C in the muffle furnace for heat preservation, an auto-combustion reaction occurs, and cool to room temperature to obtain the alumina material with a fluorite structure.
3. The electrolyte material for a low-temperature ceramic fuel cell according to claim 1, characterized in that: When the electrolyte material is an alumina material with a fluorite structure, it is prepared by the following method. Specifically: Mix aluminum nitrate nonahydrate or aluminum hydroxide, an ammonium salt, urea, and water evenly to make the concentration of aluminum nitrate or aluminum hydroxide in the system 0.5-5 M. Place the mixed material in an oven and dry it at 120 °C for 8-12 hours to form an alumina precursor; transfer the alumina precursor to a muffle furnace, heat to 600-800 °C and sinter at a constant temperature for 4-12 hours to remove residual impurities and obtain the alumina material with a fluorite structure.
4. The electrolyte material for a low-temperature ceramic fuel cell according to claim 1, characterized in that: When the electrolyte material is an alumina material with a fluorite structure, it is prepared by the following method. Specifically: Mix aluminum nitrate nonahydrate and water to make the concentration of aluminum nitrate in the solution 0.5-5 M; add citric acid powder to the solution at a ratio of 5-10 g of aluminum nitrate nonahydrate plus 0.5-2.0 g of granular citric acid. Place the mixed material in an oven and dry it at 120 °C for 3-12 hours to form an alumina precursor; transfer the alumina precursor to a muffle furnace, heat to 600-800 °C and sinter at a constant temperature for 4-12 hours to remove residual impurities and obtain the alumina material with a fluorite structure.
5. The electrolyte material for a low-temperature ceramic fuel cell according to claim 1, characterized in that: When the electrolyte material is an alumina material with a fluorite structure, it is prepared by the following method. Specifically: Put aluminum nitrate nonahydrate into a muffle furnace, control the heating rate to rise to 600-800 °C at 10-20 °C / min to decompose aluminum nitrate, keep the temperature at 600-800 °C for heat preservation and sintering for 4-12 hours, and cool naturally or take it out of the muffle furnace directly for standby.
6. The electrolyte material for a low-temperature ceramic fuel cell according to claim 1, characterized in that: When the electrolyte material is a cerium-doped alumina material with a fluorite structure, it is prepared by the following method. Specifically: Mix aluminum nitrate nonahydrate and cerium nitrate hexahydrate at a molar ratio of 4-9:1-3 to obtain a mixture; mix the mixture, citric acid, and water evenly. Add 0.5-2.0 g of granular citric acid according to 5-10 g of the mixture to make the concentration of aluminum nitrate in the system 0.5-5 M. Place the mixed material in an oven and dry it at 120 °C for 5-12 hours to form an alumina precursor; transfer the alumina precursor to a muffle furnace, heat to 600-800 °C and sinter at a constant temperature for 4-12 hours to remove residual impurities and obtain the cerium-doped alumina material with a fluorite structure.
7. The electrolyte material for a low-temperature ceramic fuel cell according to claim 1, characterized in that: When the electrolyte material is cerium-doped fluorite-structured alumina material, it is prepared by the following method: Mix aluminum nitrate nonahydrate and cerium nitrate hexahydrate at a molar ratio of 4-9:1-3 to obtain a mixture; without adding any combustion aids, put the mixture into a muffle furnace, control the heating rate at 6-10 °C / min and heat up to 750-800 °C to decompose aluminum nitrate and cerium nitrate, keep it warm and sinter at 750-800 °C for 6-10 hours, and cool it naturally or take it out of the muffle furnace directly for standby.
8. Use of the electrolyte material according to claim 1 in constructing a ceramic fuel cell, characterized in that, Specifically: The ceramic fuel cell uses fluorite-structured alumina or cerium-doped fluorite-structured alumina powder as the electrolyte material, and uses NCAL as the symmetric electrode of the fuel cell; Fill the NCAL electrode, fluorite-structured alumina or cerium-doped fluorite-structured alumina powder, and NCAL into a steel mold in sequence, and press at a pressure of 6-12 MPa to obtain an NCAL / electrolyte / NCAL structure battery.