Lithium titanium aluminum phosphate as well as preparation method and application thereof

Abstract

The invention provides lithium titanium aluminum phosphate and a preparation method and application thereof, and belongs to the field of solid-state batteries, and the preparation method of the lithium titanium aluminum phosphate comprises the following steps: adding a titanium source, a lithium source, an aluminum source and a phosphorus source into a solvent to obtain a mixed solution; raising the temperature of the mixed solution to a first preset temperature, adding an oxidizing agent, then raising the temperature to a second preset temperature, and carrying out a reaction to obtain a head product; sequentially filtering, washing and drying the primary product to obtain an intermediate product; and mixing the intermediate product with an auxiliary agent, and calcining to obtain the lithium titanium aluminum phosphate. By optimizing the raw material ratio and the treatment process, high-activity titanium hydroxide colloid is generated through oxidizing of an oxidizing agent and hydrolysis of a titanium source, transformation of a titanium aluminum lithium phosphate phase and formation of crystal nucleuses are promoted, meanwhile, the primary particle size and morphology can be effectively controlled, growth and fusion of particles are hindered through decomposition in the calcination process by introducing an auxiliary agent, and the stability of the product is improved. The crystallinity of the lithium titanium aluminum phosphate is improved, the particle size is reduced, and the ionic conductivity is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of solid-state batteries, in particular to a lithium aluminum titanium phosphate and a preparation method and application thereof. BACKGROUND

[0002] With the rapid development of the new energy vehicle industry, solid-state batteries are an important development direction of power batteries due to their high energy density, excellent safety and long cycle life. However, solid-state batteries still face many challenges, such as the ionic conductivity of solid-state electrolytes, the stability of the electrode / electrolyte interface, and high cost. Lithium aluminum titanium phosphate has important application value in the field of solid-state batteries due to its good ionic conductivity and chemical stability.

[0003] Currently, the preparation process of lithium aluminum titanium phosphate mainly includes solid-phase sintering and sol-gel methods, etc. These methods generally have some limitations, and usually need to be sintered at a high temperature of 700℃ or above to obtain lithium aluminum titanium phosphate materials with good crystallinity. However, the high-temperature sintering process can easily lead to particle growth, making it difficult to prepare nanoscale lithium aluminum titanium phosphate particles. If the sintering temperature is too low, although particle growth can be inhibited, the crystallinity of lithium aluminum titanium phosphate will be affected, which in turn affects its ionic conductivity and chemical stability. SUMMARY

[0004] In view of the technical problems in the background art, the present application provides a lithium aluminum titanium phosphate and a preparation method and application thereof, aiming to solve the technical problem that the existing preparation process of lithium aluminum titanium phosphate cannot achieve nanoscale materials with high crystallinity.

[0005] In a first aspect, the embodiments of the present application provide a preparation method of lithium aluminum titanium phosphate, comprising the following steps: adding a titanium source, a lithium source, an aluminum source and a phosphorus source into a solvent to obtain a mixed solution; warming the mixed solution to a first preset temperature, adding an oxidizing agent, and then warming to a second preset temperature to obtain a primary product through reaction; sequentially filtering, washing and drying the primary product to obtain an intermediate product; mixing the intermediate product with an auxiliary agent, and performing calcination treatment to obtain lithium aluminum titanium phosphate.

[0006] In the technical scheme of the embodiment of the application, the titanium source, the lithium source, the aluminum source and the phosphorus source are mixed, heated, oxidized, filtered, washed, dried and calcined to prepare the titanium aluminum lithium phosphate, and the operation process is relatively simple and easy for industrialization and large-scale production. By controlling the first preset temperature and the second preset temperature, the reaction can be carried out under relatively mild conditions, avoiding harsh conditions such as high temperature and high pressure, which is conducive to the selection and maintenance of equipment. At the same time, by filtering, washing and drying, impurities generated during the reaction can be effectively removed, ensuring that the final obtained titanium aluminum lithium phosphate has high purity and meets the needs of subsequent applications. In addition, by adding an additive and calcining, the crystal structure and performance of the titanium aluminum lithium phosphate can be optimized.

[0007] In some embodiments, the molar ratio of the titanium source, the lithium source, the aluminum source and the phosphorus source is 1.7: (1.35-1.5): (0.3-0.5): (3.1-3.5).

[0008] In this embodiment, the molar ratio of titanium, lithium, aluminum and phosphorus is accurately controlled, and a specific molar ratio helps to reduce the occurrence of side reactions, thereby improving the purity of the target product titanium aluminum lithium phosphate. The composition of the titanium aluminum lithium phosphate material is more uniform, the structure is more stable, which is conducive to improving its physical and chemical properties, and thus is conducive to its use in the field of solid-state batteries. At the same time, a reasonable molar ratio makes the crystal structure of the prepared titanium aluminum lithium phosphate more stable, which is conducive to its long-term stable operation in high temperature, high pressure or strong electrolyte environment.

[0009] In some embodiments, the titanium source is one or more of butyl titanate, isopropyl titanate, and tetraethyl titanate; and / or, the lithium source is one or more of lithium acetate, lithium nitrate, and lithium acetate; and / or, the aluminum source is one or more of aluminum acetate and aluminum nitrate; and / or, the phosphorus source is phosphorous acid; and / or, the solvent is one or more of anhydrous ethanol, isopropyl alcohol, and ethylene glycol.

[0010] In this embodiment, organic titanium compounds such as butyl titanate, isopropyl titanate, and tetraethyl titanate have high reactivity, which can promote the reaction, increase the reaction rate and yield; lithium salts such as lithium acetate, lithium nitrate, and lithium acetate have good solubility in the selected solvent, which helps to form a uniform mixed solution, thereby improving the uniformity and purity of the final product; aluminum sources such as aluminum acetate and aluminum nitrate are easily dissolved and reacted in the selected solvent, which helps to control the reaction conditions, avoid side reactions, and improve the selectivity of the target product; phosphorous acid as a phosphorus source can provide the required phosphorus element, and its specific chemical properties help to optimize the structure and performance of the product and improve its performance in specific applications; solvents such as anhydrous ethanol, isopropyl alcohol, and ethylene glycol have low toxicity and volatility, and have less impact on the environment and operating personnel, in line with the principles of green chemistry. In this application, by selecting appropriate raw materials and solvents, the generation of by-products can be reduced, the purity of the target product lithium aluminum titanium phosphate can be improved, and the application requirements can be met.

[0011] In some embodiments, the first preset temperature is 70-90°C; and / or, the second preset temperature is 180-250°C; and / or, the pressure of the reaction is 2-5 MPa, and the reaction time is 15-30 h.

[0012] In this embodiment, at the first preset temperature, preheating of the mixed solution helps to fully dissolve the raw materials and start the reaction; at the second preset temperature, the reaction rate is accelerated, which is beneficial to the generation of the target product. A higher second preset temperature helps to promote the complete reaction and reduce the presence of unreacted raw materials. At the same time, within the above pressure range, the activity and reaction rate of the reactants can be improved, the occurrence of side reactions can be inhibited, and the product purity can be improved. Therefore, in this application, under suitable temperature and pressure, the reaction time can be shortened to 15-30 h, the production efficiency can be improved, and the production cost can be reduced.

[0013] In some embodiments, the oxidizing agent is hydrogen peroxide; and / or, the concentration of the oxidizing agent is 10-30 wt%; and / or, the molar ratio of the oxidizing agent to the phosphorus source is (1.2-1.5):1.

[0014] In this embodiment, hydrogen peroxide as an oxidizing agent can effectively oxidize the reactants and promote the generation of the target product. Further, by controlling the concentration of hydrogen peroxide, the intensity of the oxidation reaction can be accurately controlled to avoid excessive oxidation or insufficient oxidation. The molar ratio of the oxidizing agent to the phosphorus source helps to ensure that the phosphorus source is fully reacted, thereby improving the product purity.

[0015] In some embodiments, the auxiliary agent is one or more of ammonium carbonate, ammonium acetate, and oxalic acid.

[0016] In the embodiment, the auxiliary agent decomposes at high temperature, which can hinder the growth and fusion of particles, optimize the crystal structure and morphology, and improve the electrochemical performance of the lithium titanium aluminum phosphate.

[0017] In some embodiments, the mass ratio of the auxiliary agent to the intermediate product is (0.1-0.15): 1.

[0018] In the embodiment, the appropriate amount of the auxiliary agent can effectively promote the crystal growth and structure optimization. Excessive auxiliary agent can cause excessive gas during calcination, resulting in loose material structure and affecting the mechanical strength and electrochemical performance of the material. Too little auxiliary agent can not fully play its role.

[0019] In some embodiments, the calcination temperature is 400-600℃, the heating rate is 100-200℃ / h, and the holding time is 4-10h; and / or, the calcination atmosphere is air or oxygen.

[0020] In the embodiment, the appropriate calcination temperature helps the full reaction of the components in the intermediate product and the growth of the crystal, forming a lithium titanium aluminum phosphate material with good crystallinity. The appropriate heating rate can avoid temperature gradient stress caused by too fast heating, prevent material cracking, and ensure the uniformity of the calcination process. The holding time of 4-10h is sufficient for the reaction to proceed fully and the crystal structure to be stable, thereby improving the electrochemical performance of the material. Calcination in air or oxygen atmosphere can further oxidize and remove residual organic matter and impurities, improving the purity of the final product.

[0021] In a second aspect, the embodiments of the present application provide a lithium titanium aluminum phosphate, which is prepared by the preparation method of the lithium titanium aluminum phosphate of the first aspect. The ionic conductivity of the lithium titanium aluminum phosphate is ≥6.00×10 -4 S / cm.

[0022] In the technical solution of the embodiments of the present application, by optimizing the preparation method, the obtained lithium titanium aluminum phosphate material has high ionic conductivity, which can significantly improve the rate performance and cycle stability of the lithium ion battery and prolong the service life of the battery.

[0023] In a third aspect, the embodiments of the present application provide a battery, which includes a positive electrode, a negative electrode, and an electrolyte. The electrolyte includes the lithium titanium aluminum phosphate of the second aspect.

[0024] In the embodiment, the battery contains the above-mentioned lithium titanium aluminum phosphate material, and thus has the advantages of high power density, long cycle life, high energy efficiency, and excellent rate performance.

[0025] The above description is only a summary of the technical solutions of the present application. In order to make the technical means of the present application more clear and understandable, the specific embodiments of the present application can be implemented according to the content of the description, and in order to make the above and other purposes, characteristics and advantages of the present application more obvious and easy to understand, the following specific embodiments of the present application are described. BRIEF DESCRIPTION OF DRAWINGS

[0026] In order to more clearly illustrate the technical solutions of the present application, the following will briefly introduce the drawings used in the present application. Obviously, the drawings described below are only some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained without creative labor on the basis of these drawings.

[0027] Figure 1 The preparation method flow chart of lithium aluminum titanium phosphate provided for the embodiments of the present application is shown in the figure. Figure 2 The SEM image of lithium aluminum titanium phosphate provided for the embodiment 1 of the present application is shown in the figure. Figure 3 The SEM image of lithium aluminum titanium phosphate provided for the comparative example 1 of the present application is shown in the figure. Figure 4 The XRD image of lithium aluminum titanium phosphate provided for the embodiment 1 and the comparative example 1 of the present application is shown in the figure. DETAILED DESCRIPTION

[0028] The embodiments of the technical solutions of the present application will be described in detail below in combination with the drawings. The following embodiments are only used to more clearly illustrate the technical solutions of the present application, and therefore only serve as examples, and cannot limit the protection scope of the present application.

[0029] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the present application belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the present application; the terms "include" and "have" and any variations thereof in the specification and claims of the present application and the above description of drawings are intended to cover non-exclusive inclusion.

[0030] In the description of the embodiments of the present application, the technical terms "first", "second", etc. are only used to distinguish different objects, and cannot be understood as indicating or implying relative importance or implicitly indicating the number, specific order or primary and secondary relationship of the indicated technical features. In the description of the embodiments of the present application, the meaning of "a plurality of" is two or more, unless otherwise specifically limited.

[0031] Reference to“an embodiment” herein means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of the application. The appearances of the phrase“in an embodiment” in various places in the specification are not necessarily all referring to the same embodiment, nor are they necessarily all directed to the same embodiment, or to a common alternative embodiment. One of ordinary skill in the art will readily recognize from the disclosure herein a wide variety of ways that the embodiments described can be combined, sub-combined, substituted, modified and / or altered in various ways.

[0032] In the description of the embodiments of the application, the term“and / or” is merely an association relationship of the associated objects, which means that there can be three relationships, for example, A and / or B, which can represent the three cases of A alone, A and B together, and B alone. In addition, the character“ / ” herein generally represents an“or” relationship between the front and rear associated objects.

[0033] In the description of the embodiments of the application, the term“a plurality of” refers to two or more (including two), and similarly, “a plurality of groups” refers to two or more groups (including two groups), and “a plurality of pieces” refers to two or more pieces (including two pieces).

[0034] At present, the preparation process of lithium titanium aluminum phosphate mainly includes solid phase sintering method and sol-gel method, etc. These methods generally have some limitations, and usually need to be sintered at a high temperature of 700 DEG C or above to obtain lithium titanium aluminum phosphate material with good crystallinity. However, the high-temperature sintering process is easy to cause particle growth, and it is difficult to prepare nanoscale lithium titanium aluminum phosphate particles; if the sintering temperature is too low, although the particle growth can be inhibited, the crystallinity of lithium titanium aluminum phosphate will be affected, and then the ion conductivity and chemical stability will be affected.

[0035] In order to solve the technical problem that the existing preparation process of lithium titanium aluminum phosphate is difficult to realize high-crystallinity nanoscale material, the application provides a lithium titanium aluminum phosphate and a preparation method and application thereof. By optimizing the raw material ratio and processing technology, the technical effects of improving the crystallinity of the product, reducing the particle size and improving the ion conductivity can be achieved, and then the cycle stability and rate performance of the battery are also improved.

[0036] Please refer to Figure 1 , in a first aspect, the application provides a preparation method of lithium titanium aluminum phosphate, comprising the following steps: S1. adding a titanium source, a lithium source, an aluminum source and a phosphorus source into a solvent to obtain a mixed solution; S2. heating the mixed solution to a first preset temperature, adding an oxidizing agent, and then heating to a second preset temperature to obtain a primary product by reaction; S3. sequentially filtering, washing and drying the primary product to obtain an intermediate product; S4. mixing the intermediate product with an additive and calcining to obtain lithium titanium aluminum phosphate.

[0037] In the present application, by fully dissolving and mixing the raw materials, a uniform mixture is formed, the mixture is heated to a first preset temperature to activate the reactants and make them reach a reactive state, then an oxidizing agent is added and heated to a second preset temperature to make the reactants fully react, the oxidizing agent provides oxygen atoms to participate in the oxidation reaction and promote the formation of titanium, lithium, aluminum and phosphorus into primary products; by filtration, the solid primary products are separated from the liquid to remove unreacted raw materials and by-products; by washing and drying, further remove the surface-attached impurities and solvents to obtain intermediate products; finally, the intermediate products are mixed with an aid agent and calcined at high temperature to prevent the particles from growing and fusing at high temperature, obtaining high-crystallinity nanoscale titanium aluminum lithium phosphate; wherein the first preset temperature and the second preset temperature are both less than 250°C, preferably, the first preset temperature is less than 100°C and the second preset temperature is less than 250°C.

[0038] Further, in some embodiments, the molar ratio of the titanium source, the lithium source, the aluminum source and the phosphorus source is 1.7: (1.35~1.5): (0.3~0.5): (3.1~3.5).

[0039] In the present application, the appropriate molar ratio ensures the accuracy of the chemical composition, avoids the formation of other by-products, and optimizes the purity and performance of the target product. Specifically, the molar ratio of the titanium source, the lithium source, the aluminum source and the phosphorus source can be 1.7:1.35:0.3:3.1, 1.7:1.45:0.4:3.25, 1.7:1.5:0.5:3.5, or any value within the range of 1.7: (1.35~1.5): (0.3~0.5): (3.1~3.5).

[0040] Further, in some embodiments, the titanium source is one or more of butyl titanate, isopropyl titanate, tetraethyl titanate; and / or, the lithium source is one or more of lithium acetate, lithium nitrate, lithium acetate; and / or, the aluminum source is one or more of aluminum acetate, aluminum nitrate; and / or, the phosphorus source is phosphorous acid; and / or, the solvent is one or more of anhydrous ethanol, isopropyl alcohol, ethylene glycol.

[0041] In the present application, the titanium source is an organic titanate with high purity, reducing the possibility of introducing impurities; the lithium source and the aluminum source have good solubility, ensuring the uniform distribution of lithium and aluminum elements in the solution, and the lithium source and the aluminum source are preferably lithium acetate and aluminum acetate, in the reaction process, the anion is acetate ion, and the weak acid produced is acetic acid, which has less effect on the final synthesis of titanium aluminum lithium phosphate; the phosphorus source is phosphorous acid, which can be dissolved in an alcohol solvent and is in a solid state, facilitating transportation and storage, and after forming a solution, ion-level mixing of lithium, phosphorus, titanium, and aluminum is achieved, which significantly enhances the mixing scale compared to physical mixing and other mixing forms; the alcohol solvent can achieve higher dispersion and higher pressure, which can more easily promote the hydrothermal synthesis of titanium aluminum lithium phosphate. Specifically, the amount of solvent added is 3-5 times the total mass of the titanium source, lithium source, aluminum source, and phosphorus source.

[0042] Further, in some embodiments, the first preset temperature is 70-90℃; and / or, the second preset temperature is 180-250℃; and / or, the reaction pressure is 2-5MPa, and the reaction time is 15-30h.

[0043] In the present application, the first preset temperature helps the titanium, lithium, aluminum, and phosphorus source to be more fully dissolved or dispersed, forming a uniform mixed solution; the second preset temperature promotes more complete hydrolysis and condensation reaction of the titanium and aluminum alkoxide, forming a more stable and complex oxide or hydroxide network structure; the high pressure condition helps to maintain the liquid phase reaction, accelerate the reaction process, and promote the formation of more uniform and higher crystallinity primary products; the reaction time ensures that the precursor reaction is sufficient and uniform; through the synergistic effect of the process parameters, it helps to control the rate, degree, and pathway of the chemical reaction, providing high-quality intermediate products for the subsequent calcination step.

[0044] Specifically, the first preset temperature can be 70℃, 80℃, 90℃, or any value within the range of 70-90℃, the second preset temperature can be 180℃, 190℃, 200℃, 210℃, 220℃, 230℃, 240℃, 250℃, or any value within the range of 180-250℃; the reaction pressure can be 2MPa, 3MPa, 4MPa, 5MPa, or any value within the range of 2-5MPa; the reaction time can be 15h, 18h, 20h, 22h, 25h, 28h, 30h, or any value within the range of 15-30h.

[0045] Further, in some embodiments, the oxidizing agent is hydrogen peroxide; and / or, the concentration of the oxidizing agent is 10-30wt%; and / or, the molar ratio of the oxidizing agent to the phosphorus source is (1.2-1.5):1.

[0046] In the present application, hydrogen peroxide is added at a certain temperature to oxidize phosphorous acid into phosphoric acid, and the water in the hydrogen peroxide can hydrolyze the titanium source into high-activity titanium hydroxide, which better promotes the conversion of lithium titanium aluminum phosphate phase, forms the crystal nucleus of precipitated conversion, and helps better control the primary particle size and morphology of lithium titanium aluminum phosphate, and more easily obtains lithium titanium aluminum phosphate with a primary particle size of nanoscale and a concentrated particle size distribution. Among them, the appropriate concentration of hydrogen peroxide ensures sufficient reactivity to complete its function. If the concentration of hydrogen peroxide is too low, it will lead to insufficient oxidation capacity, and it cannot effectively complete the required oxidation step or the reaction rate is too slow. If the concentration of hydrogen peroxide is too high, it will lead to a too violent reaction that is difficult to control, increasing the risk of side reactions. Further, by controlling the molar ratio of oxidizing agent to phosphorus source, it can be ensured that the phosphorus source can be fully oxidized to promote the formation of lithium titanium aluminum phosphate precursor. Specifically, the molar ratio of oxidizing agent to phosphorus source can be 1.2:1, 1.35:1, 1.5:1, or any value within the range of (1.2~1.5):1.

[0047] Further, in some embodiments, the auxiliary agent is one or more of ammonium carbonate, ammonium acetate, and oxalic acid.

[0048] In the technical solution of the embodiments of the present application, the auxiliary agent decomposes at high temperature, hinders the growth and fusion of particles, and helps to reduce the grain size of the final lithium titanium aluminum phosphate.

[0049] Further, in some embodiments, the mass ratio of the auxiliary agent to the intermediate product is (0.1~0.15):1.

[0050] In the present application, the appropriate mass ratio helps the auxiliary agent to completely decompose and volatilize during the subsequent sintering process without introducing significant impurities, and its decomposition process helps to promote the formation and crystallization of lithium titanium aluminum phosphate phase, obtaining a dense and uniform final product. Specifically, the mass ratio of the auxiliary agent to the intermediate product can be 0.1:1, 0.12:1, 0.15:1, or any value within the range of (0.1~0.15):1.

[0051] Further, in some embodiments, the calcination temperature is 400~600℃, the heating rate is 100~200℃ / h, and the holding time is 4~10h; and / or, the calcination atmosphere is air or oxygen.

[0052] In the present application, the crystallinity of the material can be improved by calcination, and compared with the conventional sintering temperature, the sintering temperature of the present application is significantly reduced, and the sintering time is also significantly shortened, thereby the grain size of the final lithium titanium aluminum phosphate can be reduced, and nanoscale lithium titanium aluminum phosphate can be obtained. Moreover, since the present application is sintered at a low temperature, it is easier to break, avoiding the difficulty in breaking caused by high-temperature sintering and the need for equipment such as a ball mill. The present application can achieve ultrafine particle size control through air flow pulverization.

[0053] In a second aspect, the embodiments of the present application provide a lithium aluminum titanium phosphate, which is prepared by the method for preparing lithium aluminum titanium phosphate according to the first aspect, and has an ionic conductivity of ≥ 6.00 x 10 -4 S / cm.

[0054] In the technical solution of the embodiments of the present application, the lithium aluminum titanium phosphate obtained has higher ionic conductivity, smaller and more concentrated primary particle size, and moderate BET, and is suitable for being used as a solid-state electrolyte.

[0055] In a second aspect, the embodiments of the present application provide a battery, which comprises a positive electrode, a negative electrode and an electrolyte, and the electrolyte comprises the lithium aluminum titanium phosphate according to the third aspect.

[0056] In the technical solution of the embodiments of the present application, the battery contains the lithium aluminum titanium phosphate material described above, and thus has the advantages of high power density, long cycle life, high energy efficiency and excellent rate performance.

[0057] Some specific examples are listed below. It should be noted that the examples described below are exemplary and are only used to explain the present application, and cannot be understood as a limitation on the present application. If a specific technology or condition is not specified in the examples, the technology or condition described in the literature in the art or according to the product manual is used. If the reagent or instrument is not specified by the manufacturer, it is a conventional product that can be obtained on the market.

[0058] I. Preparation method Example 1 The present embodiment provides a method for preparing lithium aluminum titanium phosphate, which comprises the following steps: S1. Lithium acetate, aluminum acetate and phosphorous acid are dried in a vacuum drying oven to a moisture content of less than 0.1%, and butyl titanate, lithium acetate, aluminum acetate and phosphorous acid are added to anhydrous ethanol in a molar ratio of 1.7:1.45:0.4:3.25, the mass of anhydrous ethanol is 4 times the total mass of butyl titanate, lithium acetate, aluminum acetate and phosphorous acid, and the mixture is stirred uniformly to obtain a mixed solution; S2. The mixed solution is poured into a high-pressure reaction kettle, heated to 80℃, and hydrogen peroxide with a concentration of 20wt% is introduced under stirring at a stirring speed of 200r / min, the hydrogen peroxide is introduced for 90min, the amount of hydrogen peroxide added is 1.35 times the molar amount of phosphorous acid, after the hydrogen peroxide is added, the temperature is raised to 210℃, and the reaction is continued under stirring at a pressure of 3.2MPa for 20h, the temperature is lowered and the pressure is released, and an initial product is obtained; S3. The initial product is filtered and washed, and the filter residue is dried to obtain an intermediate product; S4. The intermediate product is mixed with ammonium carbonate, the mass of the ammonium carbonate is 0.12 times the mass of the intermediate product, then the mixture is crushed to a particle size of 2.1 μm, air is introduced for calcination, the ammonia content in the furnace during the calcination process is maintained below 5 ppm, the temperature rising speed during the calcination process is 150 ℃ / h, after maintaining at 500 ℃ for 7 h, the mixture is cooled to room temperature, and then the mixture is crushed by an air flow crusher, the crushing air pressure is 0.4 MPa, the classification wheel frequency is 25 Hz, the particle size of the obtained product is 0.35 μm, and the product is vacuum packaged to obtain the lithium titanium aluminum phosphate.

[0059] Specifically, the detection results of the obtained lithium titanium aluminum phosphate are as follows: Table 1. Detection results of the lithium titanium aluminum phosphate obtained in Example 1 Example 2 The example provides a preparation method of lithium titanium aluminum phosphate. Compared with Example 1, the only difference is that the molar ratio of butyl titanate, lithium acetate, aluminum acetate and phosphorous acid is 1.7:1.35:0.3:3.1.

[0060] Specifically, the detection results of the obtained lithium titanium aluminum phosphate are as follows: Table 2. Detection results of the lithium titanium aluminum phosphate obtained in Example 2 Example 3 The example provides a preparation method of lithium titanium aluminum phosphate. Compared with Example 1, the only difference is that the molar ratio of butyl titanate, lithium acetate, aluminum acetate and phosphorous acid is 1.7:1.5:0.5:3.5.

[0061] Specifically, the detection results of the obtained lithium titanium aluminum phosphate are as follows: Table 3. Detection results of the lithium titanium aluminum phosphate obtained in Example 3 Example 4 The example provides a preparation method of lithium titanium aluminum phosphate. Compared with Example 1, the only difference is that the mass of the ammonium carbonate is 0.1 times the mass of the intermediate product.

[0062] Specifically, the detection results of the obtained lithium titanium aluminum phosphate are as follows: Table 4. Detection results of the lithium titanium aluminum phosphate obtained in Example 4 Example 5 The example provides a preparation method of lithium titanium aluminum phosphate. Compared with Example 1, the only difference is that the mass of the ammonium carbonate is 0.15 times the mass of the intermediate product.

[0063] Specifically, the detection results of the obtained lithium aluminum titanium phosphate are as follows: Table 5 Detection results of lithium aluminum titanium phosphate obtained in Example 5 Example 6 The present example provides a preparation method of lithium aluminum titanium phosphate. Compared with Example 1, the only difference is that the calcination temperature is 400℃, and the holding time is 4h.

[0064] Specifically, the detection results of the obtained lithium aluminum titanium phosphate are as follows: Table 6 Detection results of lithium aluminum titanium phosphate obtained in Example 6 Example 7 The present example provides a preparation method of lithium aluminum titanium phosphate. Compared with Example 1, the only difference is that the calcination temperature is 600℃, and the holding time is 10h.

[0065] Specifically, the detection results of the obtained lithium aluminum titanium phosphate are as follows: Table 7 Detection results of lithium aluminum titanium phosphate obtained in Example 7 Example 8 The present example provides a preparation method of lithium aluminum titanium phosphate. Compared with Example 1, the only difference is that the amount of hydrogen peroxide added is 1.2 times the molar amount of phosphorous acid.

[0066] Specifically, the detection results of the obtained lithium aluminum titanium phosphate are as follows: Table 8 Detection results of lithium aluminum titanium phosphate obtained in Example 8 Example 9 The present example provides a preparation method of lithium aluminum titanium phosphate. Compared with Example 1, the only difference is that the amount of hydrogen peroxide added is 1.5 times the molar amount of phosphorous acid.

[0067] Specifically, the detection results of the obtained lithium aluminum titanium phosphate are as follows: Table 9 Detection results of lithium aluminum titanium phosphate obtained in Example 9 Comparative Example 1 Comparative Example 1 provides a preparation method of lithium aluminum titanium phosphate, which comprises the following steps: S1. Nanometer titanium dioxide, nanometer aluminum oxide, ammonium dihydrogen phosphate and battery grade lithium carbonate were mixed according to the molar ratio of 1.7:1.45:0.4:3.25 of the titanium source, lithium source, aluminum source and phosphorus source in Example 1, after slurry was added with water, grinding to a particle size of 200 nm, after spray drying, calcining at 900℃ for 12h, after airflow crushing to a particle size of 2.7μm, adding to the sand mill for sand grinding, to obtain phosphotitanium aluminum lithium.

[0068] Specifically, the detection results of the obtained phosphotitanium aluminum lithium are as follows: Table 10 Detection results of phosphotitanium aluminum lithium obtained in Comparative Example 1 Comparative Example 2 Comparative Example 2 provides a preparation method of phosphotitanium aluminum lithium, compared with Example 1, the only difference is that no ammonium carbonate is added.

[0069] Specifically, the detection results of the obtained phosphotitanium aluminum lithium are as follows: Table 11 Detection results of phosphotitanium aluminum lithium obtained in Comparative Example 2 Comparative Example 3 Comparative Example 2 provides a preparation method of phosphotitanium aluminum lithium, compared with Example 1, the only difference is that the mass of ammonium carbonate is 0.2 times the mass of the intermediate product.

[0070] Specifically, the detection results of the obtained phosphotitanium aluminum lithium are as follows: Table 12 Detection results of phosphotitanium aluminum lithium obtained in Comparative Example 3 Comparative Example 4 Comparative Example 4 provides a preparation method of phosphotitanium aluminum lithium, compared with Example 1, the only difference is that the calcination temperature is 350℃ and the holding time is 7h.

[0071] Specifically, the detection results of the obtained phosphotitanium aluminum lithium are as follows: Table 13 Detection results of phosphotitanium aluminum lithium obtained in Comparative Example 4 Comparative Example 5 Comparative Example 5 provides a preparation method of phosphotitanium aluminum lithium, compared with Example 1, the only difference is that the calcination temperature is 650℃ and the holding time is 7h.

[0072] Specifically, the detection results of the obtained phosphotitanium aluminum lithium are as follows: Table 14 Detection results of phosphotitanium aluminum lithium obtained in Comparative Example 5 Comparative Example 6 Comparative Example 6 provides a preparation method of lithium titanium aluminum phosphate, which is different from Example 1 only in that the amount of hydrogen peroxide added is 1.1 times the molar amount of phosphorous acid.

[0073] Specifically, the detection results of the obtained lithium titanium aluminum phosphate are as follows: Table 15 Detection results of lithium titanium aluminum phosphate obtained in Comparative Example 6 Comparative Example 7 Comparative Example 7 provides a preparation method of lithium titanium aluminum phosphate, which is different from Example 1 only in that the amount of hydrogen peroxide added is 1.6 times the molar amount of phosphorous acid.

[0074] Specifically, the detection results of the obtained lithium titanium aluminum phosphate are as follows: Table 16 Detection results of lithium titanium aluminum phosphate obtained in Comparative Example 7 Comparative Example 8 Comparative Example 8 provides a preparation method of lithium titanium aluminum phosphate, which is different from Example 1 only in that in step S2, no staged temperature rise is performed, and hydrogen peroxide is directly added and heated to 210°C.

[0075] Specifically, the detection results of the obtained lithium titanium aluminum phosphate are as follows: Table 17 Detection results of lithium titanium aluminum phosphate obtained in Comparative Example 8 II. Test Methods 1. SEM Test The lithium titanium aluminum phosphate prepared in Example 1 and Comparative Example 1 was subjected to SEM detection using a MERLIN Compact field emission scanning electron microscope (model: Quanta200FEG) produced by Zeiss.

[0076] 2. XRD Test The lithium titanium aluminum phosphate prepared in the examples and Comparative Example 1 was subjected to detection using an X-ray diffractometer.

[0077] 3. Particle Size Test The particle size of the lithium titanium aluminum phosphate prepared in the examples and Comparative Example was tested using a laser particle size analyzer.

[0078] 4. BET Test The specific surface area of the lithium titanium aluminum phosphate prepared in the examples and Comparative Example was tested using nitrogen adsorption BET test method.

[0079] 5. Elemental Analysis The metal element content of the lithium titanium aluminum phosphate prepared in the examples and the comparative examples was tested by inductively coupled plasma emission spectrometry.

[0080] 6. Ion conductivity The ion conductivity of the lithium titanium aluminum phosphate prepared in the examples and the comparative examples was tested by alternating current impedance spectroscopy.

[0081] 7. Mechanical property test The mechanical properties of the membrane were tested by a universal material testing machine.

[0082] III. Analysis of test results of each example and comparative example Figures 2 to 3 The SEM images of the lithium titanium aluminum phosphate obtained in Example 1 and Comparative Example 1 are shown in FIG. 1 and FIG. 2, respectively. It can be seen that the lithium titanium aluminum phosphate obtained in Example 1 has a more concentrated particle distribution and is in a spherical shape. Figure 4 The XRD images of the lithium titanium aluminum phosphate provided in Example 1 and Comparative Example 1 are shown in FIG. 3 and FIG. 4, respectively. It can be seen that Comparative Example 1 has a certain amount of impurities, which are lithium titanium phosphate, a titanium-rich substance.

[0083] As can be seen from Tables 1 to 17, the lithium titanium aluminum phosphate obtained in the examples has higher ion conductivity, smaller and more concentrated primary particle size, and moderate BET. The lithium titanium aluminum phosphate obtained in Comparative Example 1 has low BET specific surface area and ion conductivity, and uneven particle distribution. In Comparative Example 2, no ammonium carbonate is added, resulting in excessively large crystal size. In Comparative Example 3, excessive ammonium carbonate is added, resulting in excessive gas generation during calcination, causing loose material structure and low bulk density. In Comparative Example 4, the low calcination temperature can reduce the crystal size of the lithium titanium aluminum phosphate, but the crystal structure is unstable, resulting in a decrease in electrochemical performance. In Comparative Example 5, the excessively high calcination temperature leads to an increase in crystal size. In Comparative Example 6, insufficient hydrogen peroxide results in incomplete oxidation of some reactants, and the crystal structure of the lithium titanium aluminum phosphate is incomplete, resulting in a decrease in ion conductivity. In Comparative Example 7, excessive hydrogen peroxide leads to excessive oxidation of the target product, damaging the crystal structure and surface properties, and the specific surface area of the lithium titanium aluminum phosphate decreases due to excessive oxidation, affecting its electrochemical performance. In Comparative Example 8, no staged temperature increase is performed, hydrogen peroxide is directly added and heated, the raw materials are not uniformly dispersed, and direct and rapid heating leads to local overheating or reaction out of control, resulting in unreacted or partially reacted components in the initial product, insufficient crystallinity of the final product, uneven particle distribution, and a decrease in ion conductivity.

[0084] The lithium titanium aluminum phosphate obtained in the examples and the comparative examples was pressed in a tablet press for 1 min at a pressure of 3T, and then calcined at 1000°C for 3h. The obtained membrane was sampled, and the thickness of the membrane was 10mm. The impedance, maximum force, tensile strength, and maximum force elongation rate of the membrane were measured, and the results are as follows: Table 18 Test results of the lithium aluminum titanium phosphate diaphragm From the above data, it can be seen that the lithium aluminum titanium phosphate diaphragm provided by the embodiment of the present application has small impedance, high tensile strength and strong toughness, which indicates that it has better conductivity and excellent mechanical strength, and is suitable for being used as a high-performance solid-state electrolyte. By optimizing the process parameters, the overall performance of the material is improved, which provides reliable technical support for applications such as solid-state batteries.

[0085] It should be noted that the present application is not limited to the above embodiments. The above embodiments are only examples, and embodiments having the same technical idea and playing the same role within the scope of the technical solutions of the present application are all included in the technical scope of the present application. In addition, within the scope of the main idea of the present application, various modifications that can be thought of by those skilled in the art are applied to the embodiments, and other ways constructed by combining part of the constituent elements in the embodiments are also included in the scope of the present application.

Claims

1. A method for producing a titanium aluminum lithium phosphate, characterized by, The method comprises the following steps: adding a titanium source, a lithium source, an aluminum source and a phosphorus source into a solvent to obtain a mixed solution; warming the mixed solution to a first preset temperature, adding an oxidizing agent, and then warming to a second preset temperature to obtain an initial product through reaction; sequentially filtering, washing and drying the initial product to obtain an intermediate product; mixing the intermediate product with an auxiliary agent and performing calcination treatment to obtain a titanium aluminum lithium phosphate; The second preset temperature is higher than the first preset temperature.

2. The method for preparing lithium titanium aluminum phosphate according to claim 1, characterized in that, The molar ratio of the titanium source, the lithium source, the aluminum source and the phosphorus source is 1.7:(1.35-1.5):(0.3-0.5):(3.1-3.5).

3. The method for preparing lithium titanium aluminum phosphate according to claim 2, characterized in that, The titanium source is one or more of butyl titanate, isopropyl titanate and tetraethyl titanate; and / or The lithium source is one or more of lithium acetate, lithium nitrate and lithium acetate; and / or The aluminum source is one or more of aluminum acetate and aluminum nitrate; and / or The phosphorus source is phosphorous acid; and / or The solvent is one or more of anhydrous ethanol, isopropyl alcohol and ethylene glycol.

4. The method for preparing lithium titanium aluminum phosphate according to claim 1, characterized in that, The first preset temperature is 70-90 DEG C; and / or The second preset temperature is 180-250 DEG C; and / or The reaction pressure is 2-5 MPa, and the reaction time is 15-30 h.

5. The method for preparing lithium titanium aluminum phosphate according to claim 4, characterized in that, The oxidizing agent is hydrogen peroxide; and / or The concentration of the oxidizing agent is 10-30 wt%; and / or The molar ratio of the oxidizing agent to the phosphorus source is (1.2-1.5):

1.

6. The method for preparing lithium titanium aluminum phosphate according to claim 1, characterized in that, The auxiliary agent is one or more of ammonium carbonate, ammonium acetate and oxalic acid.

7. The method of claim 6, wherein the lithium titanium aluminum phosphate is prepared by the steps of: The mass ratio of the auxiliary agent to the intermediate product is (0.1-0.15):

1. ​ 8. The method of claim 1, wherein the lithium titanium aluminum phosphate is prepared by the steps of: The calcination treatment temperature is 400-600 DEG C, the warming rate is 100-200 DEG C / h, and the holding time is 4-10 h; and / or ​ The calcination atmosphere is air or oxygen.

9. A titanium aluminum lithium phosphate characterized in that, lithium titanium aluminum phosphate having an ionic conductivity ≥ 6.00 x 10 -4 S / cm, prepared by the process according to any one of claims 1 to 8.

10. A battery comprising a positive electrode, a negative electrode, and an electrolyte, characterized by, The electrolyte comprises the titanium aluminum lithium phosphate of claim 9.

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