A lithium lanthanum zirconium oxide material and a preparation method thereof

Abstract

The present invention belongs to the technical field of materials, and relates to a lithium lanthanum zirconium oxide material and a preparation method thereof. The preparation method of the lithium lanthanum zirconium oxide material comprises the following steps: dissolving raw materials including a lithium salt and a zirconium salt in a solvent, then adding lanthanum oxide, adjusting the pH, adding a chelating agent and stirring evenly, and then adding a thickening agent until the solution becomes a gel-like substance to obtain a precursor gel-like substance, and obtaining the lithium lanthanum zirconium oxide material after drying and calcining. The preparation method of the present invention has both the advantages of accurate control of components, less pollution in the preparation process, and simple process of the solid-phase method, and the advantages of low phase-forming temperature and uniform powder particle size of the liquid-phase methods such as the sol-gel method and the co-precipitation method.

Description

Technical Field

[0001] The present invention belongs to the technical field of materials and relates to a lithium lanthanum zirconium oxide material and a preparation method thereof. Background Art

[0002] With the rapid development of ceramic-based solid-state lithium batteries with high intrinsic safety, the industry and researchers have put forward new requirements for high-performance ceramic electrolyte substrates and lithium oxide electrolyte powders. In particular, the demand for sub-micron electrolyte powders is becoming increasingly urgent because the physical and chemical properties such as the particle size and component uniformity of the electrolyte powder directly affect the preparation and electrochemical performance of ceramic electrolyte substrates and solid-state lithium batteries.

[0003] Taking the Li 7 La 3 Zr 2 O 12 (LLZO)-based materials as an example, researchers usually use synthesis processes such as solid-phase method, co-precipitation method, hydrothermal method, sol-gel method, organic chelating combustion method, and microwave-assisted synthesis method to prepare powders. Among them, the solid-phase method is the most traditional synthesis method, which has disadvantages such as high phase formation temperature and large powder particle size. For traditional co-precipitation method and hydrothermal method, there are disadvantages such as inconsistent precipitation of various types of ions and serious segregation of powder components. However, for preparation processes such as sol-gel method, organic chelating combustion method, and microwave-assisted synthesis method, although small-sized nano or sub-micron powders can be obtained, there are disadvantages such as a large amount of organic matter used and a large amount of flue gas emissions during the calcination process, which is not conducive to large-scale batch production. At the same time, there will be a phenomenon of excessive shrinkage and cracking when preparing ceramic substrates subsequently. Therefore, there is an urgent need to develop a new process that can prepare sub-micron powders with uniform components and low phase formation temperature, and has a simple preparation process and is convenient for large-scale batch production. Summary of the Invention

[0004] The purpose of the present invention is to provide a lithium lanthanum zirconium oxide material and a preparation method thereof in view of the deficiencies of the existing LLZO-based materials

[0005] One object of the present invention is to provide a lithium lanthanum zirconium oxide material, and the phase formation temperature of the lithium lanthanum zirconium oxide material is 700-900 °C, and the average particle size is 0.1-5 μm.

[0006] Another object of the present invention is to provide a preparation method of the above lithium lanthanum zirconium oxide material, including the following steps:

[0007] Dissolve raw materials including lithium salt and zirconium salt in a solvent, then add lanthanum oxide, adjust the pH, add a chelating agent and stir evenly, and then add a thickening agent until the solution becomes a gel-like substance to obtain a precursor gel-like substance, and obtain a lithium lanthanum zirconium oxide material after drying and calcining.

[0008] In the above preparation method, the solvent is a liquid capable of dissolving the raw materials, which may include water, preferably one or more of pure water, deionized water, and ultrapure water.

[0009] In the above preparation method, the lithium salt is an inorganic salt containing lithium element, including but not limited to one or more of lithium nitrate, lithium acetate, lithium oxalate, lithium carbonate, lithium phosphate, dilithium hydrogen phosphate, and lithium molybdate.

[0010] In the above preparation method, the zirconium salt is an inorganic salt containing zirconium element, including but not limited to one or more of zirconium nitrate, zirconium acetate, and zirconyl nitrate.

[0011] Preferably, the raw materials further include inorganic salts of doping elements. The doping elements include but not limited to one or more of tantalum, scandium, titanium, aluminum, magnesium, niobium, gallium, cerium, molybdenum, hafnium, and tin. The inorganic salts of doping elements can include nitrates, acetates, carbonates, etc. of the doping elements.

[0012] Preferably, the concentrations of the raw materials including lithium salt and zirconium salt in the solvent are 0.1 - 10 mol / L, and more preferably 0.2 - 5 mol / L.

[0013] The addition amounts of the raw materials including lithium salt and zirconium salt and lanthanum oxide are determined according to the final target product.

[0014] Preferably, the pH is adjusted to: 0 < pH < 7; more preferably, the pH is adjusted to: 0 < pH ≤ 6, and even more preferably, the pH is adjusted to 1 - 5. The acids used for adjusting the pH can include nitric acid, acetic acid, oxalic acid, acrylic acid, etc.

[0015] In the present invention, by adjusting the pH to be acidic, the particle size of the product can be controlled, which is beneficial to obtaining a lithium lanthanum zirconate oxide material with uniform size and small particle size.

[0016] Preferably, the chelating agent is one or more of citric acid, ethylenediaminetetraacetic acid, nitrilotriacetic acid, tartaric acid, and glycine.

[0017] In the present invention, a chelating agent is added to chelate metal ions into organometallic salts and attach them to the surface of the nucleating oxide, without segregation during the subsequent process of heating and evaporating water, which is beneficial to obtaining a lithium lanthanum zirconate oxide material with uniform composition.

[0018] Preferably, the molar ratio of metal ions in the raw materials including lithium salt and zirconium salt to the chelating agent is 1:0.1 - 10, and more preferably 1:0.1 - 5.

[0019] Preferably, the thickening agent is one or more of polyvinyl alcohol, polyvinylpyrrolidone, polyethylene glycol, polyacrylic acid, polymethacrylic acid, and polyacrylamide.

[0020] The thickener added in the present invention can increase the viscosity of the solution and reduce the sedimentation rate of oxide particles (sedimentation will cause serious segregation of the components of the final product).

[0021] The addition amount of the thickener can be exemplified as 1-5 wt% of the solution mass.

[0022] Preferably, the drying temperature is 70-300 °C, more preferably 80-250 °C, and still more preferably 100-200 °C. Preferably, the drying time is 5-35 h, more preferably 8-30 h.

[0023] Preferably, the calcination temperature is 600-950 °C, more preferably 650-900 °C, and still more preferably 700-850 °C. Preferably, the calcination temperature is 0.5-8 h, more preferably 1-6 h, and still more preferably 1.5-4 h.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] 1. The present invention provides a novel preparation method of submicron lithium lanthanum zirconium oxide material, which has the advantages of accurate control of components, less pollution in the preparation process and simple process of the solid-phase method, and the advantages of low phase-forming temperature and uniform powder particle size of the liquid-phase methods such as sol-gel method and co-precipitation method;

[0026] 2. In the preparation process of the lithium lanthanum zirconium oxide material of the present invention, by adjusting the pH to 0 < pH < 7, the particle size of the product lithium lanthanum zirconium oxide material can be controlled, which is beneficial to obtaining a lithium lanthanum zirconium oxide material with uniform size and small particle size;

[0027] 3. In the preparation process of the lithium lanthanum zirconium oxide material of the present invention, a chelating agent is added to chelate metal ions into organometallic salts and attach them to the surface of the nucleating oxide, without segregation during the subsequent process of heating and evaporating water, which is beneficial to obtaining a lithium lanthanum zirconium oxide material with uniform components;

[0028] 4. In the preparation process of the lithium lanthanum zirconium oxide material of the present invention, the added thickener can increase the viscosity of the solution and reduce the sedimentation rate of oxide particles, which is beneficial to no segregation of product components;

[0029] 5. The lithium lanthanum zirconium oxide material prepared by the present invention has the advantages of low phase-forming temperature, uniform powder particle size, small particle size and good sintering characteristics. Description of the Drawings

[0030] Figure 1 XRD diffraction pattern of the Li 7 La 3 Zr 2 O 12 material prepared in Example 1;

[0031] Figure 2 The Li prepared for Example 1 7 La 3 Zr 2 O 12 SEM pattern of the material;

[0032] Figure 3 The Li prepared for Comparative Example 1 7 La 3 Zr 2 O 12 XRD diffraction pattern of the material;

[0033] Figure 4 The Li prepared for Comparative Example 2 7 La 3 Zr 2 O 12 SEM pattern of the material. Detailed implementation manners

[0034] The technical solutions of the present invention will be further described and illustrated below through specific examples and drawings. It should be understood that the specific examples described herein are only used to assist in understanding the present invention and are not used for specific limitations of the present invention. And the drawings used herein are only for better illustrating the disclosed content of the present invention and do not have a limiting effect on the protection scope. If there is no special description, the raw materials used in the embodiments of the present invention are all commonly used raw materials in the art, and the methods used in the embodiments are all conventional methods in the art.

[0035] Example 1

[0036] The Li provided in this example 7 La 3 Zr 2 O 12 The material is prepared by the following preparation method:

[0037] Weigh 0.07 mol of lithium nitrate (LiNO 3 ) and 0.02 mol of zirconium nitrate (Zr(NO 3 ) 4) It is dissolved in 100 mL of water to form a solution, and 0.015 mol of lanthanum oxide powder is weighed and poured into the above solution; then, under the stirring state with a rotation speed of 400 rpm, 0.5 mol / L nitric acid solution is slowly added dropwise to adjust the pH value of the slurry to 3; 0.3 mol of chelating agent ethylenediaminetetraacetic acid is added and stirred evenly; thickening agent polyvinyl alcohol (the addition amount of polyvinyl alcohol is 2.5 wt% of the suspension slurry) is slowly added to the above suspension slurry, and stirred at 400 rpm until the suspension slurry becomes a jelly-like substance to obtain a precursor jelly-like substance; the above precursor jelly-like material is poured into a crucible and dried at 180 °C for 24 hours; finally, the dried foam-like precursor material is calcined at 850 °C for 2 hours to obtain the LLZO target finished product powder.

[0038] The Li prepared in Example 1 7 La 3 Zr 2 O 12 The XRD diffraction pattern and SEM pattern of the material are as Figure 1 and Figure 2 shown. It can be seen from Figure 1 that the prepared finished product powder material shows high crystallinity and no impurity peaks, and is the designed target product; it can be observed from Figure 2 that the particle size distribution of the finished product powder material is relatively uniform, and the average particle size is about 3 μm.

[0039] The Li prepared in Example 1 7 La 3 Zr 2 O 12 The phase formation temperature of the material is 850 °C.

[0040] Example 2

[0041] The Li provided in this example 7 La 3 Zr 2 O 12 material is prepared by the following preparation method:

[0042] 0.21 mol of lithium acetate and 0.06 mol of zirconium acetate were weighed and dissolved in 500 mL of water to form a solution, and 0.045 mol of lanthanum trioxide powder was weighed and poured into the above solution; then, under stirring at a speed of 400 rpm, 1 mol / L oxalic acid solution was slowly added dropwise to adjust the pH value of the slurry to 1; 0.5 mol of chelating agent tartaric acid was added and stirred evenly; thickener polyethylene glycol was slowly added to the above suspension slurry (the amount of polyethylene glycol added was 2.0 wt% of the suspension slurry), and stirred at 400 rpm until the suspension slurry became a colloid to obtain a precursor colloid; the above precursor colloid material was poured into a crucible and dried at 150°C for 30 hours; finally, the dried foamed precursor material was calcined at 750°C for 4 hours to obtain the LLZO target finished powder.

[0043] Example 2 Li prepared 7 La 3 Zr 2 O 12 The particle size of the material is uniform, with an average particle size of about 0.8μm and a phase formation temperature of 850℃.

[0044] Example 3

[0045] The Li provided in this embodiment 7 La 3 Zr 1.5 Ta 0.5 O 12 The material was prepared by the following preparation method:

[0046] 0.14 mol of lithium acetate, 0.03 mol of zirconium acetate and 0.01 mol of tantalum nitrate were weighed and dissolved in 300 mL of water to form a solution, and 0.03 mol of lanthanum trioxide powder was weighed and poured into the above solution; then, under stirring at a speed of 400 rpm, 0.5 mol / L acetic acid solution was slowly added dropwise to adjust the pH value of the slurry to 2; 0.1 mol of chelating agent citric acid was added and stirred thoroughly; thickener polyvinyl pyrrolidone (polyvinyl pyrrolidone was added in an amount of 1.5 wt% of the suspension slurry) was slowly added to the above suspension slurry, and stirred at 400 rpm until the suspension slurry became a colloid to obtain a precursor colloid; the above precursor colloid material was poured into a crucible and dried at 200°C for 18 hours; finally, the dried foamed precursor material was calcined at 800°C for 3 hours to obtain the LLZTO target finished powder.

[0047] Example 3 Li prepared 7 La 3 Zr 1.5 Ta 0.5 O 12 The particle size of the material is uniform, with an average particle size of about 1.3μm and a phase formation temperature of 800℃.

[0048] Example 4

[0049] The Li 7 La 3 Zr 1.0 Sc 0.5 Nb 0.5 O 12 material is prepared by the following preparation method:

[0050] Weigh 0.21 mol of lithium oxalate, 0.06 mol of zirconium nitrate, 0.03 mol of scandium acetate and 0.03 mol of cerium nitrate, dissolve them in 800 mL of water to form a solution, and weigh 0.09 mol of lanthanum sesquioxide powder and pour it into the above solution; then, under the stirring state with a rotation speed of 300 rpm, slowly add 0.5 mol / L nitric acid solution to adjust the pH value of the slurry to 4; add 0.2 mol of chelating agent citric acid and stir well; slowly add thickener polyvinyl alcohol to the above suspension slurry (the addition amount of polyvinyl alcohol is 3 wt% of the suspension slurry), stir at 300 rpm until the suspension slurry becomes a jelly-like substance to obtain a precursor jelly-like substance; pour the above precursor jelly-like material into a crucible and dry it at 160 °C for 20 hours; finally, calcine the dried foam-like precursor material at 820 °C for 3 hours to obtain Li 7 La 3 Zr 1.0 Sc 0.5 Nb 0.5 O 12 powder.

[0051] The Li 7 La 3 Zr 1.0 Sc 0.5 Nb 0.5 O 12 material prepared in Example 4 has uniform particle size, with an average particle size of about 2 μm, and the phase formation temperature is 820 °C.

[0052] Comparative Example 1

[0053] The difference between Comparative Example 1 and Example 1 is that no chelating agent ethylenediaminetetraacetic acid is added during the preparation process, and the others are the same as in Example 1.

[0054] The obtained Li 7 La 3 Zr 2 O 12 XRD pattern is as shown in Figure 3 Figure, and the finished powder material has poor phase formation and impurity peaks.

[0055] Comparative Example 2

[0056] The difference between Comparative Example 2 and Example 1 is that nitric acid solution was not added to adjust the pH during the preparation process, and the others are the same as in Example 1.

[0057] The obtained Li 7 La 3 Zr 2 O 12 SEM pattern is shown in Figure 4. It can be seen that there are large particles in the finished powder material and there are also impurity peaks.

[0058] All aspects, embodiments, and features of the present invention should be considered illustrative in all respects and not limiting the present invention. The scope of the present invention is only defined by the claims. Without departing from the spirit and scope of the claimed invention, those skilled in the art will appreciate other embodiments, modifications, and uses.

[0059] In the preparation method of the present invention, the order of each step is not limited to the listed order. For those of ordinary skill in the art, without creative efforts, the sequential changes of each step are also within the protection scope of the present invention. In addition, two or more steps or actions can be carried out simultaneously.

[0060] Finally, it should be noted that the specific embodiments described herein are only illustrative examples of the present invention and do not limit the implementation manner of the present invention. Those skilled in the technical field of the present invention can make various modifications or supplements to the described specific embodiments or use similar methods to replace them. It is not necessary and impossible to list all the implementation manners here. And these obvious changes or variations derived from the essence of the present invention still belong to the protection scope of the present invention. Interpreting them as any additional limitations is contrary to the spirit of the present invention.

Claims

1. A preparation method of a lithium lanthanum zirconium oxide material, characterized in that, the phase formation temperature of the lithium lanthanum zirconium oxide material is 700 - 900 °C, and the average particle size is 0.8 - 1.3 μm. The preparation method comprises the following steps: Dissolve raw materials including a lithium salt and a zirconium salt in a solvent, then add lanthanum oxide. After adjusting the pH, add a chelating agent and stir evenly, and then add a thickening agent until the solution becomes a gel-like substance to obtain a precursor gel-like substance. After drying and calcining, a lithium lanthanum zirconium oxide material is obtained; The lithium salt is an inorganic salt containing lithium element, including one or more of lithium nitrate, lithium acetate, lithium oxalate, lithium carbonate, lithium phosphate, dilithium hydrogen phosphate, lithium molybdate; the zirconium salt is an inorganic salt containing zirconium element, including one or more of zirconium nitrate, zirconium acetate, zirconyl nitrate; Adjust the pH to: 0 < pH ≤ 2; The chelating agent is one or more of ethylenediaminetetraacetic acid, nitrilotriacetic acid, tartaric acid, glycine; The calcination temperature is 700 - 850 °C, and the calcination time is 0.5 - 8 h.

2. The preparation method according to claim 1, characterized in that, the raw materials further include inorganic salts of doping elements, and the doping elements include one or more of tantalum, scandium, titanium, aluminum, magnesium, niobium, gallium, cerium, molybdenum, hafnium, tin.

3. The preparation method according to claim 1, characterized in that, the concentration of the raw materials including the lithium salt and the zirconium salt in the solvent is 0.1 - 10 mol / L.

4. The preparation method according to claim 1, characterized in that, the molar amount of the metal ions in the raw materials including the lithium salt and the zirconium salt to the chelating agent is 1:0.1 - 10.

5. The preparation method according to claim 1, characterized in that, the drying temperature is 70 - 300 °C, and the drying time is 5 - 35 h.

6. A lithium lanthanum zirconium oxide material, characterized in that, the phase formation temperature of the lithium lanthanum zirconium oxide material is 700 - 900 °C, and the average particle size is 0.8 - 1.3 μm; the preparation method of the lithium lanthanum zirconium oxide material comprises the following steps: Dissolve raw materials including a lithium salt and a zirconium salt in a solvent, then add lanthanum oxide. After adjusting the pH, add a chelating agent and stir evenly, and then add a thickening agent until the solution becomes a gel-like substance to obtain a precursor gel-like substance. After drying and calcining, a lithium lanthanum zirconium oxide material is obtained; The lithium salt is an inorganic salt containing lithium element, including one or more of lithium nitrate, lithium acetate, lithium oxalate, lithium carbonate, lithium phosphate, dilithium hydrogen phosphate, lithium molybdate; the zirconium salt is an inorganic salt containing zirconium element, including one or more of zirconium nitrate, zirconium acetate, zirconyl nitrate; Adjust the pH to: 0 < pH ≤ 2; The chelating agent is one or more of ethylenediaminetetraacetic acid, nitrilotriacetic acid, tartaric acid, glycine; The calcination temperature is 700 - 850 °C, and the calcination time is 0.5 - 8 h.

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