N-doped beta ''-AlON solid electrolyte powder and preparation method thereof

Abstract

The invention discloses a preparation method of N-doped beta ''-AlON solid electrolyte powder, which comprises the following steps: (1) slurry preparation: weighing absolute ethyl alcohol and a dispersing agent, adding the dispersing agent into the absolute ethyl alcohol, uniformly stirring to prepare a mixed solution, weighing aluminum source powder, lithium source powder, sodium source powder and nitrogen source powder to prepare mixed powder, adding the mixed powder into the mixed solution, and uniformly stirring to prepare the slurry; adding the mixed powder into the mixed solution, and fully stirring until the mixed powder is uniformly mixed to prepare mixed slurry; (2) grinding to prepare precursor slurry: fully grinding the mixed slurry to prepare the precursor slurry; (3) spray drying: performing spray drying on the wet-ground precursor slurry to obtain spray-dried powder; and (4) calcining: calcining the spray-dried powder in a nitrogen atmosphere, and keeping the temperature after calcining to obtain the N-doped beta ''-AlON powder.

Description

Technical Field

[0001] The present invention relates to the technical field of sodium salt batteries, and in particular to N-doped β"-AlON solid electrolyte powder and a preparation method thereof. Background Art

[0002] Sodium salt batteries are a type of high-temperature sodium battery with the characteristics of stable product properties, high safety, long service life, wide range of applications, easily available and non-toxic raw materials, and simple and pollution-free waste recycling process. Sodium salt batteries have been integrated by GE's global R&D center and the technology is already at a relatively mature stage. It has been applied in 25 countries around the world and has built energy storage projects such as solar energy, wind power combinations, peak management, and communication base stations.

[0003] The electrolyte used in sodium salt batteries is β-alumina ceramic. As the core material of sodium salt batteries, β-alumina ceramic can provide strong support for sodium salt batteries, thereby ensuring their high performance and high safety. At the same time, due to the continuous expansion of the application fields of energy storage sodium batteries and the continuous innovation of technology, the importance of β-alumina ceramics is becoming more and more obvious.

[0004] The electrolyte ceramics prepared from β"-alumina powder in the prior art have the following technical problems: 1. Due to the inherent properties of β"-alumina, its resistivity is limited to 3.5-5Ω·cm. The resistivity directly affects the battery's high-power output, sustained output capacity, and charging speed. 2. The chemical bond of β"-alumina is Al-O, which has limited strength. Therefore, the achievable strength of β"-alumina is 210-230 MPa. The strength affects the safety of the battery during later use. When subjected to thermal shock, vibration, etc., the electrolyte ceramic will break, causing the entire battery to fail to function properly and shortening the battery's service life.

[0005] Therefore, with the rapid development of the energy storage industry, higher requirements are placed on sodium salt batteries, which need to have higher electrical conductivity, higher structural strength and greater current flow rate. Therefore, the preparation of an electrolyte material with better performance becomes the key. Summary of the Invention

[0006] The first object of the present invention is to provide a method for preparing N-doped β"-AlON solid electrolyte powder.

[0007] The second object of the present invention is to provide an N-doped β"-AlON solid electrolyte powder.

[0008] The first object of the present invention is implemented by the following technical solution: a method for preparing N-doped β"-AlON solid electrolyte powder, which comprises the following steps: (1) Slurry preparation: Weigh anhydrous ethanol and a dispersant, add the dispersant to the anhydrous ethanol and stir evenly to prepare a mixed solution, then weigh aluminum source powder, lithium source powder, sodium source powder and nitrogen source powder to prepare a mixed powder, add the mixed powder to the mixed solution and stir thoroughly until the mixture is evenly mixed to prepare a mixed slurry. The role of adding the nitrogen source is to increase the strength and conductivity of the electrolyte ceramic prepared later; (2) Grinding to prepare precursor slurry: Grind the mixed slurry thoroughly to obtain precursor slurry; (3) Spray drying: spray drying the wet-milled precursor slurry to obtain spray-dried powder; (4) Calcination: The spray-dried powder is calcined in a nitrogen atmosphere and kept warm after calcination to obtain N-doped β"-AlON powder. The structural stability of the powder is improved by calcination. The purpose of keeping warm is to allow high temperature to penetrate the product and cook the product, so as to achieve better sintering effect. By selecting nitrogen source raw materials with a fixed structure and content, and inserting nitrogen elements during the synthesis process under nitrogen protection, β"-AlON powder with a specific composition is directionally synthesized. In addition, by sand grinding the raw materials to reduce the powder crystal size to 1-1.2μm, it is ensured that the nitrogen element can be evenly and effectively inserted, forming a uniform solid solution structure.

[0009] The combination of wet grinding and spray granulation ensures that the granulated powder after calcination has good fluidity and can be effectively filled into the sagger, solving the problem of granulated powder voids and uneven accumulation. Granulated materials within a certain particle range are selected for calcination to ensure that the material is evenly filled into the sagger during the calcination process, with good dispersion and uniform powder crystals, thus obtaining β"-AlON with a stable crystal phase and fixed nitrogen content.

[0010] Furthermore, in step (1), the mixed powder is added to the mixed solution and stirred thoroughly, and the solid content and viscosity of the mixed slurry are controlled during the stirring process.

[0011] Furthermore, the mixed slurry has a solid content of 40%-50% and a viscosity of 400-1500 cp.

[0012] Furthermore, in the step (2), during the grinding process of the mixed slurry, it is necessary to control the solid content of the precursor slurry to be 40%-50%, the viscosity to be 400-1500cp, the particle size D50 to be 1-1.2μm, and D90 to be less than 3μm.

[0013] In step (1) and step (2), the solid content and viscosity of the mixed slurry and the precursor slurry need to be controlled. Since the solid content affects the grinding effect, the solid content and viscosity are tested multiple times and fine-tuned by adding a small amount of anhydrous ethanol to ensure smooth grinding. The purpose of testing the viscosity is to ensure the smooth progress of spray drying and reduce the energy consumption of the spraying process. The lower the viscosity, the better.

[0014] Furthermore, in step (3), the particle size of the spray-dried powder is D50>40 μm.

[0015] Furthermore, in the calcination step, the calcination temperature is 1200-1280° C., the holding time is 2-4 hours, and the volume ratio of nitrogen atmosphere to air is nitrogen:air>1:1. The nitrogen atmosphere has the function of preventing the diffusion of internal nitrogen sources and anti-oxidation.

[0016] Furthermore, the mixed powder comprises the following raw materials in parts by mass: 55-95 parts of the aluminum source; 2-8 parts of the lithium source; 5-20 parts of the sodium source; and 1-20 parts of the nitrogen source.

[0017] Furthermore, the aluminum source powder is a calcined product of γ-alumina or pseudo-boehmite; The lithium source powder is any one of lithium carbonate, lithium hydroxide monohydrate or lithium acetate; The sodium source powder is any one of sodium hydroxide, sodium carbonate or sodium acetate; The nitrogen source powder is any one of AlON, aluminum nitride or magnesium nitride.

[0018] Furthermore, the dispersant is polyacrylamide, and the amount of the dispersant added accounts for 1%-3% of the mixed powder.

[0019] The second object of the present invention is implemented by the following technical solution: N-doped β"-AlON solid electrolyte powder is prepared by the above-mentioned preparation method of N-doped β"-AlON solid electrolyte powder.

[0020] The advantages of the present invention are: using special N source raw materials, by introducing N atoms into the β"-alumina lattice, N atoms are inserted to form β"-AlON with better performance. Figure 1 In the preparation process, the mixed slurry is ground by wet grinding to a particle size of 1-1.2μm (D50) and D90 <3μm, and then spray-dried and granulated to a particle size of D50 >40μm. This ensures that the powder is evenly filled into the sagger during the calcination process, thereby obtaining β"-AlON with a stable crystal phase and fixed nitrogen content. This avoids under- and over-burning caused by uneven filling, ensuring product stability and consistency.

[0021] The β"-AlON of this scheme is formed by inserting a part of N into β"-alumina to form a negative trivalent N 3- Replacement part O 2- The solid solution has excellent structural and functional properties. On the one hand, the Al-N bond has a higher strength than the Al-O bond, making the β"-AlON electrolyte stronger than β"-alumina, with a strength of more than 280. This improves the battery's ability to resist external impact during use, improves safety, extends the battery's service life, and reduces its cost. On the other hand, N 3- O 2- There is one more site for binding with Na+. One N atom replaces one oxygen atom, which increases the number of conductive sodium ions. This can increase the sodium ion content in the electrolyte and reduce the resistivity to below 2.33. β"-AlON has higher ionic conductivity, with the conductivity increased to above 0.429, which is conducive to improving the battery's high power output and continuous output capacity, and the charging speed will also be faster. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0023] Figure 1 This is a process flow chart for preparing N-doped β"-AlON solid electrolyte powder according to the present invention; Figure 2 The XRD diffraction patterns of Example 3 and Comparative Example 4 of the present invention are shown. DETAILED DESCRIPTION

[0024] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0025] Example 1: (1) Slurry preparation: Weigh 100 g of anhydrous ethanol and 1 g of dispersant respectively and add them to a stirring tank. Stir for 10 min to prepare a mixed solution. 83.8 g of γ-alumina, 2.3 g of lithium carbonate, 10.6 g of sodium hydroxide, and 3.2 g of aluminum nitride were weighed to prepare a mixed powder, which was added to the mixed solution in the stirring tank while stirring. After the addition was completed, the mixture was stirred for 30 minutes until the mixture was uniformly mixed to obtain a mixed slurry. During the mixing process, a small amount of anhydrous alcohol was added to make the viscosity of the mixed slurry 663 cp; (2) Grinding to prepare precursor slurry: Turn on the sand mill and fully grind the mixed slurry to obtain the precursor slurry. The precursor slurry is ground to a particle size D50 of 1.05 μm. During the grinding process, a small amount of anhydrous alcohol can be added to make the viscosity of the precursor slurry 1265 cp; (3) Spray drying: The wet-milled precursor slurry is transferred to a spray drying tower for spray drying to obtain a spray-dried powder with a particle size of D50 = 47 μm, and anhydrous ethanol is recovered; (4) Calcination: The spray-dried powder was loaded into a sagger, covered and transferred to a push plate kiln. The temperature was raised to 1250 °C in a nitrogen atmosphere and calcined. The temperature was kept at this temperature for 3 h. After the calcination, the powder was cooled and poured out of the sagger for sealed storage to obtain N-doped β"-AlON powder.

[0026] Example 2: (1) Slurry preparation: Weigh 100 g of anhydrous ethanol and 1 g of dispersant respectively and add them to a stirring tank. Stir for 10 min to prepare a mixed solution. 67.5 g of γ-alumina powder, 2.3 g of lithium carbonate, 10.9 g of sodium hydroxide, and 19.3 g of aluminum oxynitride were weighed to prepare a mixed powder, which was added to the mixed solution in the stirring tank while stirring. After the addition was completed, the mixture was stirred for 30 minutes until the mixture was uniformly mixed to obtain a mixed slurry. During the mixing process, a small amount of anhydrous alcohol was added to make the viscosity of the mixed slurry 617 cp; (2) Grinding to prepare precursor slurry: Turn on the sand mill and fully grind the mixed slurry to obtain the precursor slurry. The precursor slurry is ground to a particle size D50 of 1.12 μm. During the grinding process, a small amount of anhydrous alcohol can be added to make the viscosity of the precursor slurry 1240 cp; (3) Spray drying: The wet-milled precursor slurry is transferred to a spray drying tower for spray drying to obtain a spray-dried powder with a particle size of D50 = 53 μm, and anhydrous ethanol is recovered; (4) Calcination: The spray-dried powder was loaded into a sagger, covered and transferred to a push plate kiln. The temperature was raised to 1280 °C in a nitrogen atmosphere and calcined. The temperature was kept at this temperature for 4 h. After the calcination, the powder was cooled and poured out of the sagger for sealed storage to obtain N-doped β"-AlON powder.

[0027] Example 3: (1) Slurry preparation: Weigh 100 g of anhydrous ethanol and 1 g of dispersant respectively and add them to a stirring tank. Stir for 10 min to prepare a mixed solution. 82 g of γ-alumina, 2.3 g of lithium carbonate, 11.5 g of sodium hydroxide, and 4.1 g of aluminum nitride were weighed to prepare a mixed powder, which was added to the mixed solution in the stirring tank while stirring. After the addition was completed, the mixture was stirred for 30 minutes until the mixture was uniformly mixed to obtain a mixed slurry. During the mixing process, a small amount of anhydrous alcohol was added to make the viscosity of the mixed slurry 632 cp; (2) Grinding to prepare precursor slurry: Turn on the sand mill and fully grind the mixed slurry to prepare the precursor slurry. The precursor slurry is ground to a particle size D50 of 1.11 μm. During the grinding process, a small amount of anhydrous alcohol can be added to make the viscosity of the precursor slurry 1202 cp; (3) Spray drying: The wet-milled precursor slurry is transferred to a spray drying tower for spray drying to obtain a spray-dried powder with a particle size of D50 = 58 μm, and anhydrous ethanol is recovered; (4) Calcination: The spray-dried powder was loaded into a sagger, covered and transferred to a push plate kiln. The temperature was raised to 1230 °C in a nitrogen atmosphere and calcined. The temperature was kept at this temperature for 2 h. After the calcination, the powder was cooled and poured out of the sagger for sealed storage to obtain N-doped β"-AlON powder.

[0028] Example 4: (1) Slurry preparation: Weigh 100 g of anhydrous ethanol and 1 g of dispersant respectively and add them to a stirring tank. Stir for 10 min to prepare a mixed solution. 82.7 g of γ-alumina, 3.7 g of lithium acetate, 10.4 g of sodium hydroxide, and 3.3 g of aluminum nitride were weighed to prepare a mixed powder, which was added to the mixed solution in the stirring tank while stirring. After the addition was completed, the mixture was stirred for 30 minutes until the mixture was uniformly mixed to obtain a mixed slurry. During the mixing process, a small amount of anhydrous alcohol was added to make the viscosity of the mixed slurry 653 cp; (2) Grinding to prepare precursor slurry: Turn on the sand mill and fully grind the mixed slurry to obtain the precursor slurry. The precursor slurry is ground to a particle size D50 of 1.03 μm. During the grinding process, a small amount of anhydrous alcohol can be added to make the viscosity of the precursor slurry 1299 cp; (3) Spray drying: The wet-milled precursor slurry is transferred to a spray drying tower for spray drying to obtain a spray-dried powder with a particle size of D50 = 61 μm, and anhydrous ethanol is recovered; (4) Calcination: The spray-dried powder was loaded into a sagger, covered and transferred to a push plate kiln. The temperature was raised to 1280 °C in a nitrogen atmosphere and calcined. The temperature was kept at this temperature for 4 h. After the calcination, the powder was cooled and poured out of the sagger for sealed storage to obtain N-doped β"-AlON powder.

[0029] Comparative Example 1: The difference from Example 3 is that there is no nitrogen source and the composition of the raw materials remains unchanged; (1) Slurry preparation: Weigh 100 g of anhydrous ethanol and 1 g of dispersant respectively and add them to a stirring tank. Stir for 10 min to prepare a mixed solution. 82 g of γ-alumina, 2.3 g of lithium carbonate, and 11.5 g of sodium hydroxide were weighed to prepare a mixed powder, which was added to the mixed solution in the stirring tank while stirring. After the addition was completed, the mixture was stirred for 30 minutes until it was uniformly mixed to obtain a mixed slurry. During the mixing process, a small amount of anhydrous alcohol was added to make the viscosity of the mixed slurry 547 cp; (2) Grinding to prepare precursor slurry: Turn on the sand mill and grind the mixed slurry to obtain the precursor slurry. The precursor slurry is ground to a particle size D50 of 1.11 μm. During the grinding process, a small amount of anhydrous alcohol can be added to make the viscosity of the precursor slurry 1338 cp; (3) Spray drying: The wet-milled precursor slurry is transferred to a spray drying tower for spray drying to obtain a spray-dried powder with a particle size of D50 = 58 μm, and anhydrous ethanol is recovered; (4) Calcination: The spray-dried powder was loaded into a sagger, covered and transferred to a push plate kiln. The temperature was raised to 1230 °C in a nitrogen atmosphere and calcined. The temperature was kept at this temperature for 2 h. After the calcination, the powder was cooled and poured out of the sagger for sealed storage to obtain N-doped β"-AlON powder.

[0030] Comparative Example 2: The difference from Example 3 is that the protective atmosphere uses argon; (1) Slurry preparation: Weigh 100 g of anhydrous ethanol and 1 g of dispersant respectively and add them to a stirring tank. Stir for 10 min to prepare a mixed solution. 82 g of γ-alumina, 2.3 g of lithium carbonate, 11.5 g of sodium hydroxide, and 4.1 g of aluminum nitride were weighed to prepare a mixed powder, which was added to the mixed solution in the stirring tank while stirring. After the addition was completed, the mixture was stirred for 30 minutes until it was uniformly mixed to obtain a mixed slurry. During the mixing process, a small amount of anhydrous alcohol was added to make the viscosity of the mixed slurry 611 cp; (2) Grinding to prepare precursor slurry: Turn on the sand mill and fully grind the mixed slurry to obtain the precursor slurry. The precursor slurry is ground to a particle size D50 of 1.11 μm. During the grinding process, a small amount of anhydrous alcohol can be added to make the viscosity of the precursor slurry 1307 cp; (3) Spray drying: The wet-milled precursor slurry is transferred to a spray drying tower for spray drying to obtain a spray-dried powder with a particle size of D50 = 58 μm, and anhydrous ethanol is recovered; (4) Calcination: The spray-dried powder is loaded into a sagger, covered and transferred to a push plate kiln, heated to 1230°C in an argon atmosphere and calcined. After calcination, the temperature is kept at this temperature for 2 hours. After calcination, the powder is cooled, poured out of the sagger and sealed for storage to obtain a powder.

[0031] Comparative Example 3: The difference from Example 3 is that the nitrogen source is non-AlON, aluminum nitride or magnesium nitride; (1) Slurry preparation: Weigh 100 g of anhydrous ethanol and 1 g of dispersant respectively and add them to a stirring tank. Stir for 10 min to prepare a mixed solution. 82 g of γ-alumina, 2.3 g of lithium carbonate, 11.5 g of sodium hydroxide, and 3.5 g of silicon nitride were weighed to prepare a mixed powder, which was added to the mixed solution in the stirring tank while stirring. After the addition was completed, the mixture was stirred for 30 minutes until it was uniformly mixed to obtain a mixed slurry. During the mixing process, a small amount of anhydrous alcohol was added to make the viscosity of the mixed slurry 679 cp; (2) Grinding to prepare precursor slurry: Turn on the sand mill and fully grind the mixed slurry to prepare the precursor slurry. The precursor slurry is ground to a particle size D50 of 1.11 μm. During the grinding process, a small amount of anhydrous alcohol can be added to make the viscosity of the precursor slurry 1391 cp; (3) Spray drying: The wet-milled precursor slurry is transferred to a spray drying tower for spray drying to obtain a spray-dried powder with a particle size of D50 = 58 μm, and anhydrous ethanol is recovered; (4) Calcination: The spray-dried powder was loaded into a sagger, covered and transferred to a push plate kiln. The temperature was raised to 1230 °C in a nitrogen atmosphere and calcined. The temperature was kept at this temperature for 2 h. After the calcination, the powder was cooled and poured out of the sagger for sealed storage to obtain N-doped β"-AlON powder.

[0032] Comparative Example 4: Adopting the existing preparation method of β"-alumina powder; (1) Preparation of sodium precursor powder: Weigh Na2CO3 and α-Al2O3, mix them in a mass ratio of Na2O / Al2O3 of 1:6, and add the weighed Na2CO3 and α-Al2O3 to deionized water for ball milling. During the ball milling, add polymethacrylic acid as a dispersant to obtain a sodium precursor powder slurry. The ratio of the total mass of Na2CO3 and α-Al2O3 to the mass of deionized water is 1:1, and the ratio of the mass of polymethacrylic acid to the total mass of Na2CO3 and α-Al2O3 is 0.001. (2) Preparation of lithium precursor powder: Li2CO3 and α-Al2O3 are weighed and mixed in a Li2O / Al2O3 mass ratio of 1:4. The weighed Li2CO3 and α-Al2O3 are added to deionized water for ball milling. During the ball milling, polymethacrylic acid is added as a dispersant to obtain a lithium precursor powder slurry. The ratio of the total mass of Li2CO3 and α-Al2O3 to the mass of deionized water is 1:1, and the ratio of the mass of polymethacrylic acid to the total mass of Li2CO3 and α-Al2O3 is 0.001. (3) adding a water-soluble polyacrylic acid type polyelectrolyte such as polymethacrylic acid during the sodium precursor powder preparation step and the lithium precursor powder preparation step; (4) Preparation of β-alumina powder: Sodium precursor powder and lithium precursor powder were added to anhydrous acetone at a mass ratio of 9:1, ball-milled and dried to obtain β-alumina powder. The β-alumina powder consisted of 15 wt.% Na2O, 2 wt.% Li2O and 83 wt.% Al2O3. The nitrogen-doped β"-AlON powder prepared in Example 3 and the β"-alumina powder prepared in Comparative Example 4 were subjected to X-ray diffraction analysis. Figure 2 As shown, from the comparison of the diffraction patterns of the samples, it can be seen that the first diffraction peak of β"-AlON at 8°-9° and the second diffraction peak at 15°-16° are right-biased. From the diffraction data, it can be seen that these two peaks correspond to the (003) and (006) crystal planes. Under the condition of N doping, the C axis of the β"-alumina lattice is elongated, and the corresponding crystal plane diffraction angle becomes larger and then right-biased, proving that N is effectively inserted into β"-alumina and causes changes in the lattice parameters.

[0033] Subjects: Experimental Example 1: Electrolyte ceramics prepared using the powder prepared in Example 1; Experimental Example 2: Electrolyte ceramics prepared using the powder prepared in Example 2; Experimental Example 3: Electrolyte ceramics prepared using the powder prepared in Example 3; Experimental Example 4: Electrolyte ceramics prepared using the powder prepared in Example 4; Experimental Example 5: Electrolyte ceramics prepared using the powder prepared in Comparative Example 1; Experimental Example 6: Electrolyte ceramics prepared using the powder prepared in Comparative Example 2; Experimental Example 7: Electrolyte ceramics prepared using the powder prepared in Comparative Example 3; Experimental Example 8: Electrolyte ceramics prepared using the powder prepared in Comparative Example 4; The specific preparation method of the electrolyte ceramic is as follows: the electrolyte ceramic is prepared by using the existing pressing and sintering process, a certain mass of electrolyte powder is weighed, granulated and pressed under the same environmental conditions, and then fired in a push plate kiln at a temperature of 1600°C to obtain a dense electrolyte ceramic; Specific test methods: (1) According to the test method of axial resistivity of ceramic samples, a sample is cut from a uniform sample, placed under an AC voltage of 15kHz, and the resistivity of the sample is tested at a temperature of 350℃. The conductivity is calculated using the resistivity. (2) According to the fine ceramic bending strength test method, specifically, a specimen is cut from a uniform sample and the ceramic strength test is performed according to the standard GB / T 6569-2006; Experimental examples 1-7 were set up three times in parallel, and the test results of each experimental example were averaged; Table 1: Average values ​​of conductivity and strength of test examples 1-7.

[0034]

[0035] It can be seen from the data in Table 1 that compared with the electrolyte ceramics prepared in Experimental Examples 1-4 and Control Examples 1-4, due to the special structural composition of the β"-AlON solid electrolyte powder, the ceramic sodium ion electrolyte prepared by β"-AlON has a strength of more than 280, a resistivity reduced to below 2.33, and a conductivity of more than 0.429, showing excellent functional properties.

[0036] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for preparing N-doped β"-AlON solid electrolyte powder, characterized in that: It includes the following steps: (1) Slurry preparation: Weigh anhydrous ethanol and a dispersant, add the dispersant to the anhydrous ethanol and stir evenly to prepare a mixed solution, then weigh aluminum source powder, lithium source powder, sodium source powder and nitrogen source powder to prepare a mixed powder, add the mixed powder to the mixed solution and stir thoroughly until the mixture is evenly mixed to prepare a mixed slurry; (2) Grinding to prepare precursor slurry: Grind the mixed slurry thoroughly to obtain precursor slurry; (3) Spray drying: spray drying the wet-milled precursor slurry to obtain spray-dried powder; (4) Calcination: The spray-dried powder is calcined in a nitrogen atmosphere and kept warm after calcination to obtain N-doped β"-AlON powder.

2. The method for preparing N-doped β"-AlON solid electrolyte powder according to claim 1, characterized in that: In the step (1), the mixed powder is added to the mixed solution and stirred thoroughly, and the solid content and viscosity of the mixed slurry are controlled during the stirring process.

3. The method for preparing N-doped β"-AlON solid electrolyte powder according to claim 2, characterized in that: The mixed slurry has a solid content of 40%-50% and a viscosity of 400-1500 cp.

4. The method for preparing N-doped β"-AlON solid electrolyte powder according to claim 1, characterized in that: In the step (2), during the grinding process of the mixed slurry, it is necessary to control the solid content of the precursor slurry to be 40%-50%, the viscosity to be 400-1500cp, the particle size D50 to be 1-1.2μm, and D90 to be less than 3μm.

5. The method for preparing N-doped β"-AlON solid electrolyte powder according to claim 1, characterized in that: In the step (3), the particle size of the spray-dried powder is D50>40 μm.

6. The method for preparing N-doped β"-AlON solid electrolyte powder according to claim 1, characterized in that: In the calcination step, the calcination temperature is 1200-1280° C., the holding time is 2-4 hours, and the volume ratio of nitrogen atmosphere to air is nitrogen:air>1:

1.

7. The method for preparing N-doped β"-AlON solid electrolyte powder according to claim 1, characterized in that: The mixed powder comprises the following raw materials in parts by mass: 55-95 parts of the aluminum source; 2-8 parts of the lithium source; 5-20 parts of the sodium source; and 1-20 parts of the nitrogen source.

8. The method for preparing N-doped β"-AlON solid electrolyte powder according to claim 7, characterized in that: The aluminum source powder is a calcined product of γ-alumina or pseudo-boehmite; The lithium source powder is any one of lithium carbonate, lithium hydroxide monohydrate or lithium acetate; The sodium source powder is any one of sodium hydroxide, sodium carbonate or sodium acetate; The nitrogen source powder is any one of AlON, aluminum nitride or magnesium nitride.

9. The method for preparing N-doped β"-AlON solid electrolyte powder according to claim 8, characterized in that: The dispersant is polyacrylamide, and the amount of the dispersant added accounts for 1%-3% of the mixed powder.

10. N-doped β"-AlON solid electrolyte powder prepared by the method for preparing N-doped β"-AlON solid electrolyte powder according to any one of claims 1 to 9.

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