A β-alumina powder and its preparation method

Abstract

This application relates to a β″-alumina powder and its preparation method. The method includes: mixing an aluminum source of Al2O3 and a sodium source of Na2O to obtain a β″-alumina precursor; calcining the β″-alumina precursor to obtain a β″-alumina powder semi-finished product; adding an inorganic lithium salt lithium source to the β″-alumina powder semi-finished product, followed by heat treatment to obtain β″-alumina powder. This method avoids the ball milling process involving alcohol, solves the technical problem of safety hazards caused by alcohol, simplifies the preparation process, and achieves advantages such as suitability for industrial production applications, high efficiency, and high safety.

Description

Technical Field

[0001] This application relates to the field of alumina preparation technology, and in particular to a β-alumina powder and its preparation method. Background Technology

[0002] β"-alumina powder is the most important core component in the entire solid-state battery system and a key factor in the success of solid-state battery technology. Furthermore, β"-alumina materials are widely used in sodium-nickel batteries (ZEBRA), alkali metal thermoelectric converters, and other fields. Currently, there are many methods for preparing β"-alumina powder, but most are not suitable for industrial production applications. The preparation of β"-alumina powder often requires solvent ball milling, which is time-consuming, and often involves alcohol, posing safety hazards.

[0003] Therefore, there is an urgent need to find a method for preparing β-alumina powder that is suitable for industrial production applications, highly efficient, and safe. Summary of the Invention

[0004] This application provides a β"-alumina powder and its preparation method to solve the technical problem of safety hazards in the ball milling alcohol operation in the preparation of existing β"-alumina powders.

[0005] In a first aspect, this application provides a method for preparing β-alumina powder, the method comprising:

[0006] An aluminum source of Al2O3 and a sodium source of Na2O were mixed to obtain a β-alumina precursor.

[0007] The β″-alumina precursor was calcined to obtain β″-alumina powder semi-finished product;

[0008] An inorganic lithium salt lithium source is added to the β″-alumina powder semi-finished product, followed by heat treatment to obtain β″-alumina powder.

[0009] Optionally, the aluminum source of the Al2O3 includes one of the following: α-alumina, γ-alumina, or hydrated alumina.

[0010] Optionally, the sodium source of Na2O may include one of the following: Na2CO3, NaAlO2, or NaOH.

[0011] Optionally, in the components of the β-alumina precursor, the content of Na2O is 8% to 10% by mass fraction, and the content of Al2O3 is 90% to 92%.

[0012] Optionally, the calcination process parameters include: calcination temperature of 1200℃~1250℃ and calcination time of 1h~2h.

[0013] Optionally, the inorganic lithium salt source includes one of the following: LiCl or Li2CO3.

[0014] Optionally, relative to 1 part by weight of the β-alumina powder semi-finished product, the inorganic lithium salt lithium source is 0.01 to 0.02 parts by weight.

[0015] Optionally, the temperature of the heat treatment is 600℃~800℃.

[0016] Optionally, the step of adding an inorganic lithium salt source to the β″-alumina powder semi-finished product, followed by heat treatment to obtain β″-alumina powder, further includes:

[0017] The β″-alumina powder is washed; wherein, relative to 1 part by weight of the β″-alumina powder, the washing medium is 2 to 5 parts by weight.

[0018] Secondly, this application provides a β″-alumina powder, which is prepared by the method described in any one of the embodiments of the first aspect.

[0019] The technical solutions provided in this application have the following advantages compared with the prior art:

[0020] The method for preparing β″-alumina powder provided in this application involves mixing an aluminum source (Al2O3) and a sodium source (Na2O) to obtain a β″-alumina precursor. After calcination, addition of a lithium stabilizer, and heat treatment, a β″-alumina powder with a β″ content of over 94% and high stability is obtained. This method avoids the use of ball milling with alcohol, solves the technical problems related to the safety hazards of alcohol, simplifies the preparation process, and achieves advantages such as suitability for industrial production, high efficiency, and high safety. Attached Figure Description

[0021] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0022] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 A schematic flowchart illustrating a method for preparing β-alumina powder provided in this application embodiment;

[0024] Figure 2TEM image of a β-alumina powder provided in Example 1 of this application;

[0025] Figure 3 An XRD phase analysis diagram of β-alumina powder provided for Implementation Example 1 of this application;

[0026] Figure 4 The XRD phase analysis diagram of β-alumina powder ceramic after sintering is provided for Implementation Case 1 of this application. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0028] Various embodiments of this application may exist in the form of a range; it should be understood that the description in the form of a range is merely for convenience and brevity and should not be construed as a hard limitation on the scope of this application; therefore, it should be considered that the range description has specifically disclosed all possible sub-ranges and single numerical values ​​within that range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed sub-ranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., and single numbers within the range, such as 1, 2, 3, 4, 5, and 6, regardless of the range. Furthermore, whenever a numerical range is referred to herein, it means including any referenced number (fraction or integer) within the referred range.

[0029] In this application, unless otherwise stated, directional terms such as "upper" and "lower" specifically refer to the drawing directions in the accompanying drawings. Furthermore, in the description of this application, terms such as "comprising" and "including" mean "including but not limited to." In this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. In this document, "and / or" describes the relationship between related objects, indicating that three relationships can exist; for example, A and / or B can represent: A alone, A and B simultaneously, or B alone. A and B can be singular or plural. In this document, "at least one" means one or more, and "more than one" means two or more. "At least one," "at least one of the following," or similar expressions refer to any combination of these items, including any combination of single or plural items. For example, "at least one of a, b, or c" or "at least one of a, b, and c" can both mean: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, and c can be a single or multiple.

[0030] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this application can be purchased from the market or prepared by existing methods.

[0031] Firstly, this application provides a method for preparing β-alumina powder, please refer to [link to relevant documentation]. Figure 1 The method includes:

[0032] S1. Mix the aluminum source of Al2O3 and the sodium source of Na2O to obtain the β-alumina precursor;

[0033] In some embodiments, the aluminum source of the Al2O3 includes one of the following: α-alumina, γ-alumina, or hydrated alumina.

[0034] In the embodiments of this application, one of α-alumina, γ-alumina, and hydrated alumina is selected as the aluminum source of Al2O3, which results in the synthesis of β-alumina powder with fewer impurities and higher crystallinity.

[0035] In some embodiments, the sodium source of Na2O includes one of the following: Na2CO3, NaAlO2, or NaOH.

[0036] In the embodiments of this application, one of Na2CO3, NaAlO2, and NaOH is selected as the sodium source of Na2O, which results in fewer impurities in the synthesis of β-alumina powder and requires a lower synthesis temperature.

[0037] In some embodiments, the β-alumina precursor contains, by mass fraction, 8% to 10% Na2O and 90% to 92% Al2O3.

[0038] In this embodiment, the Na2O content in the β″-alumina precursor is controlled to reduce impurities and increase the β″ phase content in the synthesized β″-alumina powder. If the Na2O content is too high, it may hinder the synthesis of β″-alumina.

[0039] - The alumina powder contains NaAlO2 impurities. If the Na2O content is too low, the β″ phase content will decrease and the β′ phase content will increase to some extent. Controlling the Al2O3 content results in fewer impurities and a higher β″ phase content in the synthesized β″-alumina powder. If the Al2O3 content is too high, the β″ phase content will decrease and the β′ phase content will increase to some extent; if the Al2O3 content is too low, the NaAlO2 impurities will appear in the synthesized β″-alumina powder to some extent. Specifically, the Na2O content can be 8%, 9%, 10%, etc., and the Al2O3 content can be 90%, 91%, 92%, etc.

[0040] S2. The β″-alumina precursor is calcined to obtain β″-alumina powder semi-finished product;

[0041] In some embodiments, the calcination process parameters include: a calcination temperature of 1200℃~1250℃ and a calcination time of 1h~2h.

[0042] In the embodiments of this application, the calcination temperature and calcination time are controlled to ensure that Al2O3 reacts with Na2O uniformly and fully.

[0043] If the calcination temperature is too high or the calcination time is too long, abnormal growth of α-alumina impurities or grains may occur to some extent. If the calcination temperature is too low or the calcination time is too short, the reaction between Al2O3 and Na2O may be insufficient, resulting in lower crystallinity of β″-alumina and a reduced content of the β″ phase. Specifically, the calcination temperature can be 1200℃, 1210℃, 1220℃, 1230℃, 1240℃, 1250℃, etc., and the calcination time can be 1h, 1.5h, 2h, etc.

[0044] S3. Add an inorganic lithium salt lithium source to the β″-alumina powder semi-finished product, and then perform heat treatment to obtain β″-alumina powder.

[0045] In some embodiments, the inorganic lithium salt lithium source includes one of the following: LiCl or Li2CO3.

[0046] In this embodiment, the inorganic lithium salt source exhibits good melting and displacement effects. LiCl and Li₂CO₃ are selected as the lithium source, and Li₂CO₃ can be melted at temperatures below 800°C. + A portion of the Na in β″-alumina is replaced by ion exchange. + .

[0047] In some embodiments, the inorganic lithium salt source is 0.01 to 0.02 parts by weight relative to 1 part by weight of the β-alumina powder semi-finished product.

[0048] In this embodiment, the amount of inorganic lithium salt source added is controlled to improve the stability of the β″ phase of β″-alumina at the ceramic sintering temperature and prevent the β″ phase from transforming into the β′ phase. If the amount of inorganic lithium salt source is too large, it will generate a Li-containing impurity phase to a certain extent; if the amount of inorganic lithium salt source is too small, the stability of the β″ phase will be poor to a certain extent. Specifically, relative to 1 part by weight of the β″-alumina powder semi-finished product, the amount of inorganic lithium salt source can be 0.01 parts by weight, 0.15 parts by weight, 0.02 parts by weight, etc.

[0049] In some embodiments, the temperature of the heat treatment is 600°C to 800°C.

[0050] In this embodiment, the heat treatment temperature is controlled to obtain the desired β-alumina powder. If the heat treatment temperature is too high, it will be industrially unsustainable and waste energy; if the heat treatment temperature is too low, the inorganic lithium salt may not melt completely, the Li ion content may decrease, the ion exchange driving force may be too small, the reaction may not proceed easily, and the heat treatment time may be too long. Specifically, the heat treatment temperature can be 600℃, 650℃, 700℃, 750℃, 800℃, etc.

[0051] In some embodiments, the addition of an inorganic lithium salt source to the β″-alumina powder semi-finished product, followed by heat treatment to obtain β″-alumina powder, further includes:

[0052] The β″-alumina powder is washed; wherein, relative to 1 part by weight of the β″-alumina powder, the washing medium is 2 to 5 parts by weight.

[0053] In this embodiment, the amount of washing medium is controlled within a certain range to effectively remove impurity ions. Excessive use of washing medium may increase production costs; insufficient use may make it difficult to completely remove impurity ions, increasing the impurity content of the β″-alumina powder. Specifically, the washing medium can be 2 parts by weight, 3 parts by weight, 4 parts by weight, or 5 parts by weight relative to 1 part by weight of the β″-alumina powder. Furthermore, the washing medium can be distilled water, high-purity water, or ethanol.

[0054] Secondly, this application provides a β-alumina powder, please refer to [link to relevant documentation]. Figure 2 The TEM image shown is of β″-alumina powder, which is prepared by the method described in any one of the embodiments of the first aspect.

[0055] The β″-alumina powder is prepared based on the above-described method for preparing β″-alumina powder. The specific steps of the preparation method for β″-alumina powder can be referred to the above embodiments. Since the β″-alumina powder adopts some or all of the technical solutions of the above embodiments, it has at least all the beneficial effects brought about by the technical solutions of the above embodiments, which will not be elaborated here.

[0056] The present application is further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the application. Experimental methods in the following embodiments that do not specify specific conditions are generally determined according to national standards. If there is no corresponding national standard, then general international standards, conventional conditions, or conditions recommended by the manufacturer are followed.

[0057] In a first aspect, this application provides a method for preparing β-alumina powder, the method comprising:

[0058] S11. The aluminum source of Al2O3 and the sodium source of Na2O are mixed to obtain the β-alumina precursor.

[0059] S21. The β″-alumina precursor is calcined to obtain β″-alumina powder semi-finished product;

[0060] S31. Add an inorganic lithium salt source to the β″-alumina powder semi-finished product, followed by heat treatment to obtain β″-alumina powder. For specific process parameters, please refer to Examples 1-3.

[0061] Example 1

[0062] 24.04 parts Na2CO3 and 84.27 parts α-alumina were used as raw materials and mixed evenly to obtain raw material powder. The powder was calcined at 1250℃ for 2 hours to synthesize β″-alumina powder. The high-temperature synthesized β″-alumina powder was thoroughly mixed with 4 parts LiCl and subjected to a second heat treatment at 700℃ for 2 hours to obtain Li-stabilized β″-alumina. The powder was then washed with 80℃ hot water for 30 minutes, filtered, rinsed with five times its weight of distilled water, and dried to obtain the final β″-alumina powder.

[0063] Example 2

[0064] 21.89 parts Na2CO3 and 85.24 parts γ-alumina were used as raw materials and mixed evenly to obtain raw material powder. The powder was calcined at 1250℃ for 2 hours to synthesize β″-alumina powder. The high-temperature synthesized β″-alumina powder was thoroughly mixed with 8 parts LiCl and subjected to a second heat treatment at 800℃ for 2 hours to obtain Li-stabilized β″-alumina. The powder was then washed with 60℃ hot water for 30 minutes, filtered, rinsed with three times its weight of distilled water, and dried to obtain the final β″-alumina powder.

[0065] Example 3

[0066] 17.25 parts NaOH and 100.85 parts hydrated alumina were mixed evenly to obtain raw material powder. The powder was calcined at 1200℃ for 2 hours to synthesize β″-alumina powder. The high-temperature synthesized β″-alumina powder was thoroughly mixed with 3.44 parts Li₂CO₃ and subjected to a second heat treatment at 800℃ for 2 hours to obtain Li-stabilized β″-alumina. The powder was then washed with 80℃ hot water for 30 minutes, filtered, rinsed with twice the weight of distilled water (based on the weight of the β″-alumina powder), and dried to obtain the final β″-alumina powder.

[0067] Example 4

[0068] 26.42 parts NaAlO2 and 89 parts α-alumina were used as raw materials and mixed evenly to obtain raw material powder. Calcination at 1200℃ for 2 hours synthesized β″-alumina powder. The high-temperature synthesized β″-alumina powder was thoroughly mixed with 4 parts LiCl and subjected to a second heat treatment at 600℃ for 2 hours to obtain Li-stabilized β″-alumina. The powder was then washed with 80℃ hot water for 30 minutes, filtered, rinsed with distilled water at four times the weight of the β″-alumina powder, and dried to obtain the final β″-alumina powder.

[0069] Comparative Example 1

[0070] 21.89 parts Na₂CO₃, 2.5 parts MgO, and 100.28 parts high-purity alumina monohydrate were mixed evenly to obtain a raw material powder. The raw material powder was then mechanically ball-milled using alcohol as the milling medium to obtain a slurry. The mass ratio of raw material powder to alcohol in the mechanical ball milling was 1:1.5, and the mass ratio of raw material powder to grinding balls was 1:3. The milling time was 16 hours. The slurry was then dried using a closed-loop spray dryer with an inlet air temperature of 190℃, an outlet air temperature of 100℃, and an atomizing disc rotation speed of 25Hz to evaporate the alcohol, thus obtaining a uniformly mixed β″-alumina precursor. This precursor was then calcined at 1100℃ for 2 hours to synthesize β″-alumina powder.

[0071] The β″ content and particle size of the β″-alumina powders prepared in Examples 1-4 and Comparative Example 1 were tested, and the results are shown in Table 1.

[0072] Table 1. β″ content and particle size of β″-alumina powder

[0073] Serial Number β" content / wt% <![CDATA[Particle size D 50 / μm]]> Example 1 96 1.0±0.5 Example 2 94 1.0±0.5 Example 3 95 1.0±0.5 Example 4 96 1.0±0.5 Comparative Example 1 87 0.7±0.5μm

[0074] In Examples 1-3, an aluminum source of Al2O3 and a sodium source of Na2O were mixed to obtain a β"-alumina precursor. After calcination, addition of a lithium stabilizer, and heat treatment, a β"-alumina powder with a β" content of over 94% and high stability was obtained. For details, please refer to... Figure 3 The XRD phase analysis diagram of β"-alumina powder in Example 1 is shown, and Figure 4 The XRD phase analysis diagram of the β″-alumina powder ceramic after sintering shows that the β″-alumina powder has strong stability. This method avoids the ball milling with alcohol, solves the technical problem of safety hazards caused by alcohol, simplifies the preparation process, and achieves the advantages of being suitable for industrial production applications, high efficiency, and high safety. In contrast, the β″-alumina powder prepared by Comparative Example 1 using another method has a more complex process, including an alcohol ball milling step, which poses certain safety hazards.

[0075] The above description is merely a specific embodiment of this application, enabling those skilled in the art to understand or implement this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A method for preparing β-alumina powder, characterized in that, The method includes: An aluminum source of Al2O3 and a sodium source of Na2O were mixed to obtain a β-alumina precursor. The β″-alumina precursor was calcined to obtain β″-alumina powder semi-finished product. The calcination temperature was 1200℃~1250℃ and the calcination time was 1h~2h. Inorganic lithium salt lithium source is added to the β″-alumina powder semi-finished product and then heat-treated to obtain β″-alumina powder. The heat treatment temperature is 600℃~800℃. In the components of the β-alumina precursor, the content of Na2O is 8% to 10% by mass fraction, and the content of Al2O3 is 90% to 92%. The inorganic lithium salt source is 0.01 to 0.02 parts by weight relative to 1 part by weight of the β-alumina powder semi-finished product. The β″-alumina powder contains more than 94% β″.

2. The method according to claim 1, characterized in that, The aluminum source of Al2O3 includes one of the following: α-alumina, γ-alumina, or hydrated alumina.

3. The method according to claim 1, characterized in that, The sodium source for Na2O includes one of the following: Na2CO3, NaAlO2, or NaOH.

4. The method according to claim 1, characterized in that, The inorganic lithium salt lithium source includes one of the following: LiCl and Li2CO3.

5. The method according to claim 1, characterized in that, The process of adding an inorganic lithium salt source to the β″-alumina powder semi-finished product and then performing heat treatment to obtain β″-alumina powder further includes: The β″-alumina powder is washed; wherein, relative to 1 part by weight of the β″-alumina powder, The washing medium is 2 to 5 parts by weight.

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