Flame synthesis method of lithium lanthanum zirconium oxygen garnet powder material

Abstract

The invention discloses a flame synthesis method of a lithium lanthanum zirconium oxygen garnet powder material. The flame synthesis method comprises the following steps: 1, preparing a precursor solution for synthesizing lithium lanthanum zirconium oxygen garnet; 2, the uniformity and stability of the precursor solution of the lithium lanthanum zirconium oxygen garnet are enhanced; 3, synthesizing a lithium lanthanum zirconium oxygen garnet powder material by using a flame synthesis process system; 4, collecting and screening the lithium lanthanum zirconium oxygen garnet powder material; and 5, testing the performance characterization of the lithium lanthanum zirconium oxygen garnet powder material. The flame synthesis method of the lithium lanthanum zirconium oxygen garnet powder material disclosed by the invention has the advantages of efficient and rapid synthesis, high purity and uniform particle size distribution.

Description

Technical Field

[0001] The present invention belongs to the technical field applicable to the preparation of lithium lanthanum zirconium oxide garnet nano-powder materials by flame synthesis, and particularly relates to a flame synthesis method for lithium lanthanum zirconium oxide garnet powder materials. Background Art

[0002] Lithium lanthanum zirconium oxide (LLZO) powder is a solid electrolyte material with high ionic conductivity, excellent chemical stability, and a wide electrochemical window, and plays an important role in solid-state lithium batteries. Its high ionic conductivity and good mechanical strength enable it to effectively inhibit the growth of lithium dendrites and improve the safety and energy density of the battery. LLZO powder is widely used in solid-state lithium batteries, all-solid-state energy storage devices, and next-generation high-energy density battery systems, and is one of the key materials for promoting the development of new energy technologies. The flame synthesis method has outstanding advantages in the preparation of high-performance nano-scale LLZO powder. The flame synthesis method can complete the reaction in an extremely short time, is suitable for large-scale continuous production, and directly generates high-purity LLZO powder, reducing the introduction of impurities; by adjusting parameters such as the flame temperature and reactant concentration, the particle size and morphology of the nanoparticles can be controlled, thereby optimizing the ionic conductivity and electrochemical performance of the material and providing high-quality electrolyte materials for the application of solid-state lithium batteries.

[0003] The following problems still need to be solved in the preparation of high-performance LLZO powder materials by the flame synthesis method: 1) Prepare an LLZO precursor solution suitable for flame synthesis; 2) The sensitivity of LLZO to lithium volatilization also increases the difficulty of composition control during the synthesis process, and the process needs to be further optimized to solve such problems.

[0004] To solve the above problems, the present invention proposes a flame synthesis method for lithium lanthanum zirconium oxide garnet powder materials. Summary of the Invention

[0005] The main object of the present invention is to provide a flame synthesis method for lithium lanthanum zirconium oxide garnet powder materials, which has the advantages of high-efficiency and rapid synthesis, high purity, and uniform particle size distribution.

[0006] To achieve the above object, the present invention provides a flame synthesis method for lithium lanthanum zirconium oxide garnet powder materials, comprising the following steps:

[0007] Step 1: Prepare a precursor solution for synthesizing lithium lanthanum zirconium oxide garnet;

[0008] Step 2: Enhance the uniformity and stability of the precursor solution of lithium lanthanum zirconium oxide garnet;

[0009] Step 3: Use a flame synthesis process system to carry out the synthesis of lithium lanthanum zirconium oxide garnet powder materials;

[0010] Step 4: Collect and screen the lithium lanthanum zirconium oxide powder material;

[0011] Step 5: Test the performance characterization of the lithium lanthanum zirconium oxide powder material.

[0012] As a further preferred technical solution of the above technical solution, Step 1 is specifically implemented as the following steps:

[0013] Step S1.1: Select raw materials, including a lithium source, a lanthanum source, a zirconium source, and a solvent;

[0014] Step S1.2: Determine the target stoichiometric ratio; at the same time, since lithium is prone to volatilization during high-temperature sintering, which may easily lead to the final product deviating from the target stoichiometric ratio, the dosage of the lithium source is appropriately increased to compensate for the volatilization of lithium during the high-temperature flame synthesis process and ensure that the final product meets the target stoichiometric ratio;

[0015] Step S1.3: Adopt the distributed dissolution method to dissolve the lithium source, lanthanum source, and zirconium source in different containers respectively.

[0016] As a further preferred technical solution of the above technical solution, Step 2 is specifically implemented as the following steps:

[0017] Step S2.1: During the dissolution and stirring process, introduce ultrasonic treatment to accelerate the dissolution of raw materials by using the cavitation effect of ultrasonic waves and break the small aggregates existing in the solution to further improve the solution uniformity;

[0018] Step S2.2: Add a complexing agent to the solution to form a stable complex with metal ions to prevent the hydrolysis or precipitation of metal ions in the solution; at the same time, adjust the pH value of the solution to weak acidity to inhibit the hydrolysis reaction of metal ions;

[0019] Step S2.3: Place the precursor solution in a temperature gradient environment, adjust the temperature to slowly rise from the first temperature to the second temperature, use the temperature change to promote the uniform distribution and complexation reaction of metal ions in the solution, and at the same time, use an inert gas to protect the precursor solution to prevent the solution from reacting with CO2 or moisture in the air and avoid the formation of impurity phases;

[0020] Step S2.4: Install an on-line viscometer and a pH sensor on the solution delivery pipeline to monitor the viscosity change and pH value of the solution in real time and link with the automatic liquid addition system to ensure that the solution is always in a stable state.

[0021] As a further preferred technical solution of the above technical solution, Step 3 is specifically implemented as the following steps:

[0022] Step S3.1: First, start the main burner to form a swirling main flame inside the reaction chamber and preheat the reaction chamber to the target temperature to reduce the temperature gradient of the precursor liquid droplets in the reaction chamber.

[0023] Step S3.2: Use a constant flow pump to transport the precursor solution of lithium lanthanum zirconium oxide garnet to the atomizer and adjust the solution flow rate to ensure uniform droplet size after atomization.

[0024] Step S3.3: Introduce the atomized droplets into the high-temperature flame, where the droplets quickly evaporate, decompose, and undergo solid-phase reactions to generate LLZO powder.

[0025] Step S3.4: Control the flame temperature and the residence time of the droplets in the flame for a preset time to ensure sufficient reaction and good crystallinity of the powder.

[0026] Step S3.5: Use an infrared thermometer to monitor the flame temperature in real time to ensure temperature stability.

[0027] As a further preferred technical solution of the above technical solution, step four is specifically implemented as the following steps:

[0028] Step S4.1: Conduct efficient filtration and collection. Use a multi-layer composite filter collector and combine vacuum filtration to collect the lithium lanthanum zirconium oxide garnet powder material generated by the reaction.

[0029] Step S4.2: Conduct intelligent vibration screening and particle size control. Screen the collected lithium lanthanum zirconium oxide garnet powder material through a vibration screening system. Through a multi-stage screening process, precisely remove large particle aggregates to obtain powder with a uniform particle size distribution, providing high-quality raw materials for subsequent processes.

[0030] Step S4.3: Carry out controllable atmosphere annealing and crystallization optimization. Place the screened powder material in a muffle furnace and conduct gradient annealing treatment in an oxygen atmosphere. The annealing process is divided into three stages: First, heat up to the first preset temperature at the first preset rate and hold for the first preset time to remove organic residues; then heat up to the second preset temperature at the second preset rate and hold for the second preset time to eliminate residual stress in the powder and promote grain growth; finally, cool down to room temperature at the third preset rate to avoid lattice defects caused by rapid cooling.

[0031] As a further preferred technical solution of the above technical solution, step five is specifically implemented as the following steps:

[0032] Step S5.1: Use X-ray diffraction testing to accurately analyze the crystal structure, lattice parameters, and phase purity of the powder material to ensure no generation of impurity phases.

[0033] Step S5.2: Use a scanning electron microscope to test, observe the morphology and particle distribution of the powder material through high resolution, and confirm the elemental composition and its uniformity by combining energy spectrum analysis;

[0034] Step S5.3: Use electrochemical impedance spectroscopy to test the ionic conductivity of the powder material within the temperature range from room temperature to the target temperature, evaluate the electrochemical performance as a solid electrolyte material, and according to the evaluation results, optimize the annealing process in Step S4.3 to increase the ionic conductivity of the powder material to the order of 10 -4 S / cm, meeting the application requirements of high-performance solid-state batteries.

[0035] The beneficial effects of the present invention are as follows:

[0036] (1) Efficient and rapid synthesis

[0037] This invention adopts the flame synthesis method, which can complete the preparation of lithium lanthanum zirconium oxide garnet powder material in an extremely short time, significantly improving the production efficiency and being suitable for large-scale industrial production.

[0038] (2) High purity and uniformity

[0039] The flame synthesis method can achieve rapid reaction and crystallization of materials at high temperature, and the generated LLZO powder has high purity and uniform particle distribution, which is beneficial to improving the electrochemical performance of the material and is suitable for high-end applications such as solid electrolytes.

[0040] (3) Energy conservation and environmental protection

[0041] Compared with the traditional high-temperature solid-phase method, the flame synthesis method reduces energy consumption and reaction time, and lowers production costs. Description of the Drawings

[0042] Figure 1 is the process schematic diagram of the present invention.

[0043] Figure 2 is the process schematic diagram of Step 1 of the present invention.

[0044] Figure 3 is the process schematic diagram of Step 2 of the present invention.

[0045] Figure 4 is the process schematic diagram of Step 3 of the present invention.

[0046] Figure 5 is the process schematic diagram of Step 4 of the present invention.

[0047] Figure 6 is the process schematic diagram of Step 5 of the present invention. Detailed Embodiments

[0048] The following description is used to disclose the present invention so that those skilled in the art can implement the present invention. The preferred embodiments in the following description are only examples, and those skilled in the art can think of other obvious variations. The basic principles of the present invention defined in the following description can be applied to other embodiments, variations, improvements, equivalent schemes, and other technical solutions without departing from the spirit and scope of the present invention.

[0049] In the preferred embodiment of the present invention, those skilled in the art should note that the raw materials and the like involved in the present invention can be regarded as the prior art.

[0050] Preferred embodiment.

[0051] As Figures 1-6 shown, the present invention discloses a flame synthesis method for lithium lanthanum zirconium oxide garnet powder materials, comprising the following steps:

[0052] Step 1: Prepare a precursor solution for synthesizing lithium lanthanum zirconium oxide garnet;

[0053] Step 2: Strengthen the uniformity and stability of the precursor solution of lithium lanthanum zirconium oxide garnet;

[0054] Step 3: Use a flame synthesis process system to carry out the synthesis of lithium lanthanum zirconium oxide garnet powder materials;

[0055] Step 4: Collect and screen the lithium lanthanum zirconium oxide garnet powder materials;

[0056] Step 5: Test the performance characterization of the lithium lanthanum zirconium oxide garnet powder materials.

[0057] Specifically, Step 1 is specifically implemented as the following steps:

[0058] Step S1.1: Select raw materials, including lithium sources, lanthanum sources, zirconium sources, and solvents (lithium sources include but are not limited to lithium carbonate (Li2CO3), lithium nitrate (LiNO3), lithium acetate (LiCH3COO), etc.; lanthanum sources include but are not limited to lanthanum sulfate (La2(SO4)3), lanthanum chloride (LaCl3), lanthanum nitrate (La(NO3)3), etc.; zirconium sources include but are not limited to zirconium oxychloride (ZrOCl2), zirconium chloride (LaCl4), zirconium nitrate (Zr(NO3)4) soluble zirconium salts; solvents include but are not limited to ethanol, propanol, acetic acid, oleic acid amide, etc.);

[0059] Step S1.2: Determine the target stoichiometric ratio Li:La:Zr = 3 - 10:1.5 - 4.5:1 - 3; meanwhile, since lithium is prone to volatilization during high-temperature sintering, which may cause the final product to deviate from the target stoichiometric ratio (affecting the material properties), lithium is prepared in excess. That is, on the basis of the target stoichiometric ratio, the dosage of the lithium source is appropriately increased to compensate for the volatilization of lithium during the high-temperature flame synthesis and ensure that the final product meets the target stoichiometric ratio;

[0060] Step S1.3: Adopt the distributed dissolution method to dissolve the lithium source, lanthanum source, and zirconium source in different containers respectively (to avoid possible local precipitation or reaction during direct mixing); the solvent is preferably ethanol (ethanol has the property of low surface tension), which is used to promote the rapid dissolution and uniform dispersion of the lithium source, lanthanum source, and zirconium source.

[0061] More specifically, step two is specifically implemented as the following steps:

[0062] Step S2.1: During the dissolution and stirring process, introduce ultrasonic treatment to accelerate the dissolution of raw materials by using the cavitation effect of ultrasonic waves and break the tiny aggregates (possibly) existing in the solution to further improve the solution uniformity;

[0063] Step S2.2: (To improve the stability of the lithium lanthanum zirconium oxide garnet precursor solution after uniform blending) Add a complexing agent (preferably citric acid) to the solution to form stable complexes with metal ions (Li + , La 3+ , Zr 4+ ) to prevent the hydrolysis or precipitation of metal ions in the solution; meanwhile, add ammonia water to adjust the pH value of the solution to weakly acidic (pH ≈ 4 - 6) to inhibit the hydrolysis reaction of metal ions;

[0064] Step S2.3: (To further improve the uniformity and stability of the precursor solution) Place the precursor solution in a temperature gradient environment, adjust the temperature to slowly rise from the first temperature (preferably at 20 - 35 °C) to the second temperature (preferably at 50 - 60 °C), use the temperature change to promote the uniform distribution and complexation reaction of metal ions in the solution. Meanwhile, use an inert gas (nitrogen or argon) to protect the precursor solution to prevent the solution from reacting with CO2 or moisture in the air and avoid the formation of impurity phases;

[0065] Step S2.4: (To ensure the solution stability of the lithium lanthanum zirconium oxide garnet precursor solution during pipeline transportation) Install an on-line viscometer and a pH sensor on the solution pipeline to monitor the viscosity change and pH value of the solution in real time and link with the automatic liquid addition system to ensure that the solution is always in a stable state.

[0066] Furthermore, step three is specifically implemented as the following steps:

[0067] Step S3.1: First, start the main burner to form a swirling main flame inside the reaction chamber and preheat the reaction chamber to the target temperature of 800 - 1000 °C to reduce the temperature gradient of the precursor droplets in the reaction chamber;

[0068] Step S3.2: Use a constant flow pump to transport the precursor solution of lithium lanthanum zirconium oxide garnet to the atomizer, and adjust the solution flow rate to 5 - 10 mL / min to ensure uniform droplet size after atomization;

[0069] Step S3.3: Introduce the atomized droplets into the high-temperature flame, where the droplets rapidly evaporate, decompose, and undergo solid-phase reactions to form LLZO powder;

[0070] Step S3.4: Control the flame temperature at 1000 - 2000 °C and the residence time of the droplets in the flame for a preset time of 0.1 - 0.5 seconds to ensure sufficient reaction and good crystallinity of the powder;

[0071] Step S3.5: Use an infrared thermometer to monitor the flame temperature in real time to ensure temperature stability.

[0072] Furthermore, step four is specifically implemented as the following steps: Step S4.1: Conduct high-efficiency filtration and collection. Use a multi-layer composite filtration collector and combine it with vacuum filtration to collect the lithium lanthanum zirconium oxide garnet powder material generated by the reaction (ensure the high-efficiency collection of the lithium lanthanum zirconium oxide garnet powder material generated by the reaction); Step S4.2: Conduct intelligent vibration screening and particle size control. Screen the collected lithium lanthanum zirconium oxide garnet powder material through a vibration screening system, and through a multi-stage screening process, precisely remove large particle agglomerates to obtain powder with a uniform particle size distribution, providing high-quality raw materials for subsequent processes; Step S4.3: Carry out controlled atmosphere annealing and crystallization optimization. Place the screened powder material in a muffle furnace and conduct gradient annealing treatment in an oxygen atmosphere. The annealing process is divided into three stages: First, heat up to the first preset temperature of 300 - 800 °C at the first preset rate of 2 - 8 °C / min and hold for the first preset time of 0.5 - 2 hours to remove organic residues; then heat up to the second preset temperature of 600 - 1200 °C at the second preset rate of 1 - 5 °C / min and hold for 1 - 3 hours to eliminate residual stress in the powder and promote grain growth; finally, cool down to room temperature at the third preset rate of 1 - 4 °C / min to avoid lattice defects caused by rapid cooling (through this annealing process, the crystallinity and structural stability of the powder can be significantly improved).

[0073] Step S4.1: Conduct efficient filtration and collection. Use a multi-layer composite filter collector and combine it with vacuum filtration to collect the lithium lanthanum zirconium oxide garnet powder material generated by the reaction (ensuring the efficient collection of the lithium lanthanum zirconium oxide garnet powder material generated by the reaction).

[0074] Step S4.2: Conduct intelligent vibration screening and particle size control. Screen the collected lithium lanthanum zirconium oxide garnet powder material through a vibration screening system. Through a multi-stage screening process, precisely remove large particle aggregates to obtain a powder with a uniform particle size distribution, providing high-quality raw materials for subsequent processes.

[0075] Step S4.3: Carry out controllable atmosphere annealing and crystallization optimization. Place the screened powder material in a muffle furnace and conduct gradient annealing treatment in an oxygen atmosphere. The annealing process is divided into three stages: First, heat up to the first preset temperature of 300 - 800 °C at the first preset rate of 2 - 8 °C / min and hold for the first preset time of 0.5 - 2 hours to remove organic residues; then heat up to the second preset temperature of 600 - 1200 °C at the second preset rate of 1 - 5 °C / min and hold for 1 - 3 hours to eliminate residual stress in the powder and promote grain growth; finally, cool down to room temperature at the third preset rate of 1 - 4 °C / min to avoid lattice defects caused by rapid cooling (through this annealing process, the crystallinity and structural stability of the powder can be significantly improved).

[0076] Preferably, step five is specifically implemented as the following steps:

[0077] Step S5.1: Use X-ray diffraction testing to precisely analyze the crystal structure, lattice parameters, and phase purity of the powder material to ensure no generation of impurity phases.

[0078] Step S5.2: Use scanning electron microscopy testing. Through high-resolution observation of the morphology and particle distribution of the powder material, combine energy spectrum analysis to confirm the elemental composition and its uniformity.

[0079] Step S5.3: Use electrochemical impedance spectroscopy testing. In the temperature range from room temperature to the target temperature of 100 °C, test the ionic conductivity of the powder material, evaluate the electrochemical performance as a solid electrolyte material, and according to the evaluation results, through optimizing the annealing process in step S4.3, increase the ionic conductivity of the powder material to 10 -3 -10 -4 S / cm magnitude to meet the application requirements of high-performance solid-state batteries.

[0080] It is worth mentioning that the technical features such as raw materials involved in this invention patent application should be regarded as the prior art. For the specific structures, working principles, possible control methods, and spatial arrangement methods of these technical features, conventional selections in the art can be adopted, and they should not be regarded as the invention points of this invention patent. This invention patent will not be further specifically elaborated.

[0081] For those skilled in the art, it is still possible to modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some of the technical features. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims

1. A flame synthesis method for lithium lanthanum zirconium oxide garnet powder material, characterized in that, It includes the following steps: Step 1: Configure the precursor solution for synthesizing lithium lanthanum zirconium oxide garnet; Step 2: Strengthen the uniformity and stability of the precursor solution of lithium lanthanum zirconium oxide garnet; Step 3: Use the flame synthesis process system to carry out the synthesis of lithium lanthanum zirconium oxide garnet powder materials; Step 4: Collect and screen the lithium lanthanum zirconium oxide garnet powder materials; Step 5: Test the performance characterization of the lithium lanthanum zirconium oxide garnet powder materials.

2. The flame synthesis method of a lithium lanthanum zirconium oxide garnet powder material according to claim 1, characterized in that, Step 1 is specifically implemented as the following steps: Step S1.1: Select raw materials, including lithium source, lanthanum source, zirconium source and solvent; Step S1.2: Determine the target stoichiometric ratio; at the same time, since lithium element is prone to volatilization during high-temperature sintering, which is likely to cause the final product to deviate from the target stoichiometric ratio, the dosage of lithium source is appropriately increased to compensate for the volatilization of lithium during the high-temperature flame synthesis process and ensure that the final product meets the target stoichiometric ratio; Step S1.3: Adopt the distributed dissolution method to dissolve the lithium source, lanthanum source and zirconium source in different containers respectively.

3. The flame synthesis method of a lithium lanthanum zirconium oxide garnet powder material according to claim 2, characterized in that, Step 2 is specifically implemented as the following steps: Step S2.1: During the dissolution and stirring process, introduce ultrasonic treatment, and use the cavitation effect of ultrasonic waves to accelerate the dissolution of raw materials and break the small aggregates existing in the solution to further improve the solution uniformity; Step S2.2: Add a complexing agent to the solution to form stable complexes with metal ions to prevent the hydrolysis or precipitation of metal ions in the solution; at the same time, adjust the pH value of the solution to weak acidity to inhibit the hydrolysis reaction of metal ions; Step S2.3: Place the precursor solution in a temperature gradient environment, adjust the temperature to slowly rise from the first temperature to the second temperature, and use the temperature change to promote the uniform distribution and complexation reaction of metal ions in the solution. At the same time, use an inert gas to protect the precursor solution to prevent the solution from reacting with CO2 or moisture in the air and avoid the generation of impurity phases; Step S2.4: Install an on-line viscometer and a pH sensor on the solution delivery pipeline to monitor the viscosity change and pH value of the solution in real time and link with the automatic liquid addition system to ensure that the solution is always in a stable state.

4. The flame synthesis method of a lithium lanthanum zirconium oxide garnet powder material according to claim 3, wherein Step 3 is specifically implemented as the following steps: Step S3.1: First start the main burner to form a swirling main flame inside the reaction chamber and preheat the reaction chamber to the target temperature to reduce the temperature gradient of the precursor droplets in the reaction chamber; Step S3.2: Use a constant flow pump to transport the precursor solution of lithium lanthanum zirconium oxide garnet to the atomizer and adjust the solution flow rate to ensure that the size of the atomized droplets is uniform; Step S3.3: Introduce the atomized droplets into the high-temperature flame, and the droplets quickly evaporate, decompose and undergo solid-phase reactions in the flame to generate LLZO powder; Step S3.4: Control the flame temperature and the preset residence time of the droplets in the flame to ensure sufficient reaction and good crystallinity of the powder; Step S3.5: Use an infrared thermometer to monitor the flame temperature in real time to ensure temperature stability.

5. The flame synthesis method of a lithium lanthanum zirconium oxide garnet powder material according to claim 4, wherein, Step 4 is specifically implemented as the following steps: Step S4.1: Conduct efficient filtration and collection, use a multi-layer composite filtration collector, combined with vacuum filtration, to collect the lithium lanthanum zirconium oxide garnet powder materials generated by the reaction; Step S4.2: Conduct intelligent vibration screening and particle size control. Screen the collected lithium lanthanum zirconium oxide garnet powder material through a vibration screening system. Through a multi-stage screening process, precisely remove large particle aggregates to obtain a powder with a uniform particle size distribution, providing high-quality raw materials for subsequent processes. Step S4.3: Carry out controlled atmosphere annealing and crystallization optimization. Place the screened powder material in a muffle furnace and perform gradient annealing treatment in an oxygen atmosphere. The annealing process is divided into three stages: First, heat up to a first preset temperature at a first preset rate and hold for a first preset time to remove organic residues. Subsequently, heat up to a second preset temperature at a second preset rate and hold for a second preset time to eliminate residual stress in the powder and promote grain growth. Finally, cool down to room temperature at a third preset rate to avoid lattice defects caused by rapid cooling.

6. The flame synthesis method of a lithium lanthanum zirconium oxide garnet powder material according to claim 5, characterized in that, Step five is specifically implemented as the following steps: Step S5.1: Use X-ray diffraction testing to precisely analyze the crystal structure, lattice parameters, and phase purity of the powder material to ensure no impurity phase is generated. Step S5.2: Use scanning electron microscopy testing to observe the morphology and particle distribution of the powder material through high resolution, and confirm the elemental composition and its uniformity by combining energy spectrum analysis. Step S5.3: Use electrochemical impedance spectroscopy to test the ionic conductivity of the powder material in the temperature range from room temperature to the target temperature, evaluate the electrochemical performance as a solid electrolyte material, and according to the evaluation results, optimize the annealing process in step S4.3 to increase the ionic conductivity of the powder material to 10 -4 S / cm order of magnitude to meet the application requirements of high-performance solid-state batteries.

Images