A monoclinic zirconia nanopowder, its preparation method and application

Abstract

This invention belongs to the field of ultrafine powder preparation and lithium battery material technology, specifically relating to a monoclinic zirconium oxide nanopowder, its preparation method, and its application. The preparation method involves dissolving zirconium oxychloride octahydrate in water to obtain a zirconium oxychloride aqueous solution, then placing it in a hydrothermal reactor and heating it to 140–160°C for a hydrothermal reaction. After the reaction is complete, the solution is cooled to room temperature and allowed to settle. Then, ammonia water is added for ammonolysis, followed by aging to completely precipitate the residual zirconium ions. The precipitate is separated, washed, and dried to obtain a zirconium hydroxide precursor. Finally, the solution is calcined at 850–950°C in air to obtain the monoclinic zirconium oxide nanopowder. The preparation method of this invention is simple and does not introduce toxic or harmful substances. The obtained nano-ZrO2 powder has a precise chemical composition, small particle size, and high Cl... ‑ Its lower content makes it suitable for use as an additive in lithium battery cathode materials.

Description

Technical Field

[0001] This invention belongs to the field of ultrafine powder preparation and lithium battery material technology, specifically relating to a monoclinic zirconia nanopowder, its preparation method, and its application. Background Technology

[0002] Zirconia (ZrO2) is a high-temperature resistant (melting point up to 2680℃), corrosion-resistant, and high-hardness (Mohs hardness 8.5) material. It not only possesses excellent physical properties, such as high strength, high hardness, good thermal shock resistance, wear resistance, and low thermal conductivity (2.09 W / mol·K), but also exhibits chemical stability, demonstrating good resistance to acid and alkali corrosion in both oxidizing and reducing atmospheres, and even showing good biocompatibility. It plays a crucial role in electronic products, ceramics, catalysis, and special refractory materials. In the lithium battery industry, specialized nano-zirconia is a high-purity nano-zirconia (purity exceeding 99%), requiring fine nanoparticle size, uniform particle size distribution, absence of hard agglomerates, minimal magnetic impurities, and excellent sphericity.

[0003] Nano-ZrO2 powder exists in three phases: monoclinic, cubic, and tetragonal, each with its own superior properties. Monoclinic ZrO2 exhibits excellent biocompatibility, good chemical stability, and a high dielectric constant, making it highly advantageous in bone plant biocoatings, catalysts, and gate dielectric layers. Cubic ZrO2 possesses excellent oxygen ion conductivity and is widely used in oxygen sensors and fuel cell electrolytes. Due to its phase transition characteristics, tetragonal ZrO2 can serve as an important raw material for toughening ceramics and zirconium-containing composite materials.

[0004] To date, there are many methods for preparing nano-ZrO2 powder, including precipitation, hydrothermal methods, sol-gel methods, and spray pyrolysis. Among these, precipitation methods are difficult to control in terms of product size, morphology, and chemical composition; sol-gel methods have long reaction cycles, expensive raw materials, and the organic solvents pose certain health risks, making them unsuitable for large-scale industrial production; spray pyrolysis methods require sophisticated equipment, are costly, and are not easily industrialized. In contrast, hydrothermal methods are simple, energy-efficient, and eliminate the need for grinding and the resulting impurities.

[0005] Patent CN109354064A reports a solvothermal method for preparing monoclinic ZrO2 nanoparticles. Specifically, it involves using zirconium alcohol as a raw material and N,N-dimethylformamide (DMF) and glacial acetic acid as a mixed solvent under surfactant-free conditions. Although this method is surfactant-free, it introduces two organic compounds, N,N-dimethylformamide (DMF) and glacial acetic acid, increasing production costs and difficulty. Furthermore, these compounds cannot be completely removed at high temperatures, and the residual organic matter becomes impurities, affecting the purity and performance of ZrO2.

[0006] Patent CN110228819A discloses a method for hydrothermal synthesis of ZrO2 powder. The specific steps are: completely dissolving ZrOCl2·8H2O in water, adding hydrogen peroxide and stirring until homogeneous, then introducing oxygen to carry out a hydrothermal reaction, followed by filtration, washing, and calcination. This method has a simple preparation process, but the large amount of oxygen involved in the reaction makes it potentially explosive.

[0007] In patent CN10187058713B, a certain concentration of alkaline aqueous solution is added dropwise to a certain amount of zirconium salt aqueous solution, stirred evenly, washed, and redispersed. This is then subjected to a hydrothermal reaction with concentrated acid, followed by centrifugation and washing to obtain monoclinic ZrO2. This method introduces the hazardous chemical concentrated acid, increasing the complexity of the process and production costs. Summary of the Invention

[0008] To address the shortcomings and deficiencies of the existing technologies, the primary objective of this invention is to provide a method for preparing monoclinic zirconium oxide nanopowder. This method uses zirconium oxychloride as a raw material and employs a hydrothermal-co-precipitation method to prepare monoclinic zirconium oxide nanopowder, simplifying the preparation process, avoiding the introduction of toxic or harmful substances, and lowering the preparation requirements. The resulting nano-ZrO2 powder exhibits precise chemical composition, small particle size, and high Cl content. - The advantage of lower content.

[0009] Another objective of this invention is to provide a monoclinic zirconia nanopowder prepared by the above method.

[0010] Another object of the present invention is to provide the application of the above-mentioned monoclinic zirconium oxide nanopowder as an additive for lithium battery cathode materials.

[0011] The objective of this invention is achieved through the following technical solution:

[0012] A method for preparing monoclinic zirconia nanopowder includes the following preparation steps:

[0013] (1) Dissolve zirconium oxychloride octahydrate in water to obtain an aqueous solution of zirconium oxychloride, then place it in a hydrothermal reactor and heat it to 140-160°C for hydrothermal reaction. After the reaction is completed, cool it to room temperature and let it stand to precipitate.

[0014] (2) Add ammonia water to the reaction solution in step (1) to carry out ammonolysis reaction, let stand and age, completely precipitate the residual zirconium ions, separate the precipitate, wash and dry it to obtain zirconium hydroxide precursor;

[0015] (3) The zirconium hydroxide precursor obtained in step (2) is calcined at 850-950°C in air to obtain the monoclinic zirconium oxide nanopowder.

[0016] Furthermore, the mass ratio of zirconium oxychloride octahydrate to water added in step (1) is 1:3 to 5.

[0017] Furthermore, in the hydrothermal reaction process described in step (1), the filling degree of the hydrothermal reactor is 70-85%.

[0018] Furthermore, the hydrothermal reaction time in step (1) is 12 to 16 hours.

[0019] Furthermore, the settling time in step (1) is 0.5–1 h. Through settling after the zirconium oxychloride octahydrate dissolution reaction, most of the zirconium ions precipitate, leaving the remaining zirconium ions in the supernatant.

[0020] Furthermore, the mass concentration of the ammonia water in step (2) is 25-28%.

[0021] Furthermore, in step (2), ammonia is added to make the pH of the mixed solution 8-10.

[0022] Furthermore, the settling and aging time in step (2) is 0.5 to 1 hour.

[0023] Furthermore, the washing described in step (2) refers to washing multiple times with pure water to reduce the Cl content in the product. - content.

[0024] Furthermore, the heat preservation and calcination treatment in step (3) takes 2 to 4 hours.

[0025] A monoclinic zirconia nanopowder was prepared by the above method.

[0026] Furthermore, the monoclinic zirconium oxide nanoparticles have a D50 particle size of <0.5 μm and a Cl content of 100 μm. - Content < 200 ppm.

[0027] The above-mentioned monoclinic zirconia nanopowder is used as an additive in lithium battery cathode materials.

[0028] The reaction process of the preparation method of this invention does not introduce other impurities, the product has high quality and is easy to process. The chemical equation for the reaction process is as follows:

[0029] ZrOCl2·8H2O+H2O→ZrO(OH)2↓+2HCl+7H2O;

[0030] NH3·H2O + HCl → NH4Cl + H2O;

[0031] ZrOCl2+2NH3·H2O→ZrO(OH)2↓+2NH4Cl;

[0032] ZrO(OH)2→ZrO2+H2O.

[0033] Compared with the prior art, the beneficial effects of the present invention are:

[0034] (1) The preparation method of this invention uses the inorganic compound zirconium oxychloride octahydrate as raw material and ammonia water as auxiliary material. Without the use of other additives, a pure monoclinic ZrO2 powder that is white, free of large particles, lumps, and inclusions can be prepared through hydrothermal treatment, ammonolysis, washing, drying, and calcination. This preparation process is simple and efficient, uses economical raw materials, requires a small amount of precipitant, and generates waste gas and waste liquid that are easy to treat, thus possessing the characteristics of being "green, environmentally friendly, and efficient".

[0035] (2) This invention first involves a hydrothermal reaction of a zirconium oxychloride aqueous solution at 140–160°C, which precipitates over 95% of zirconium ions. Then, ammonia is added to adjust the pH to 8–10 for ammonolysis, completely precipitating the remaining zirconium ions. This reduces the amount of ammonia added as a precipitant and controls the precipitation rate, resulting in finer precipitate particles and less entrainment and encapsulation of chloride ions. Consequently, the particle size and chloride ion content of the final zirconium oxide nanopowder product are reduced, improving product quality. The resulting zirconium oxide nanopowder meets the specifications required for cathode material additives in the lithium-ion battery industry.

[0036] (3) The present invention calcines the zirconium hydroxide precursor at 850-950°C in an air environment, which can ensure that the zirconium hydroxide precursor is completely converted into monoclinic zirconium oxide, and the resulting powder has a smaller particle size. Attached Figure Description

[0037] Figure 1 This is a process flow diagram of a method for preparing monoclinic zirconia nanopowder according to the present invention;

[0038] Figure 2 The image shows the XRD pattern of the monoclinic zirconia nanopowder prepared in this invention. Detailed Implementation

[0039] The present invention will be further described in detail below with reference to the embodiments and accompanying drawings, but the embodiments of the present invention are not limited thereto.

[0040] Example 1

[0041] A method for preparing monoclinic zirconia nanopowder, the process flow diagram of which is shown below. Figure 1 As shown, the specific preparation steps are as follows:

[0042] (1) Weigh 18g of raw material zirconium oxychloride octahydrate, measure 72mL of water, and completely dissolve zirconium oxychloride octahydrate in water to obtain zirconium oxychloride aqueous solution; place zirconium oxychloride aqueous solution in 100mL reactor for hydrothermal reaction, the reactor filling degree is 80%, the reaction temperature is 150℃, and the reaction time is 16h; after the reaction is completed, cool to room temperature and let stand for 1h to precipitate.

[0043] (2) After the reaction solution was settled in step (1), analytical grade ammonia (concentration of 28 wt%) was added to carry out ammonolysis reaction. When the pH of the resulting mixed solution was 8.5, the solution was allowed to stand for 0.75 h. Then the supernatant was removed. The resulting precipitate was washed with pure water several times and then dried to obtain zirconium hydroxide precursor.

[0044] (3) The zirconium hydroxide precursor was calcined at 900°C in air for 3 hours to obtain the monoclinic zirconium oxide nanopowder.

[0045] The XRD pattern of the obtained monoclinic zirconia nanopowder is shown below. Figure 2 As shown.

[0046] Example 2

[0047] A method for preparing monoclinic zirconia nanopowder, the process flow diagram of which is shown below. Figure 1 As shown, the specific preparation steps are as follows:

[0048] (1) Weigh 18g of raw material zirconium oxychloride octahydrate, measure 72mL of water, and completely dissolve zirconium oxychloride octahydrate in water to obtain zirconium oxychloride aqueous solution; place zirconium oxychloride aqueous solution in 100mL reactor for hydrothermal reaction, the reactor filling degree is 80%, the reaction temperature is 160℃, and the reaction time is 12h; after the reaction is completed, cool to room temperature and let stand for 1h to precipitate.

[0049] (2) After the reaction solution was settled in step (1), analytical grade ammonia (concentration of 28 wt%) was added to carry out ammonolysis reaction. When the pH of the resulting mixed solution was 9, the solution was allowed to stand for aging for 0.75 h. Then the supernatant was removed. The resulting precipitate slurry was washed with pure water several times and then dried to obtain zirconium hydroxide precursor.

[0050] (3) The zirconium hydroxide precursor was calcined at 850°C for 3 hours in air to obtain the monoclinic zirconium oxide nanopowder.

[0051] Example 3

[0052] A method for preparing monoclinic zirconia nanopowder, the process flow diagram of which is shown below. Figure 1 As shown, the specific preparation steps are as follows:

[0053] (1) Weigh 18g of raw material zirconium oxychloride octahydrate, measure 72mL of water, and completely dissolve zirconium oxychloride octahydrate in water to obtain zirconium oxychloride aqueous solution; place zirconium oxychloride aqueous solution in 100mL reactor for hydrothermal reaction, the reactor filling degree is 80%, the reaction temperature is 150℃, and the reaction time is 12h; after the reaction is completed, cool to room temperature and let stand for 1h to precipitate.

[0054] (2) After the reaction solution was settled in step (1) and precipitation was completed, analytical grade ammonia (concentration of 28 wt%) was added to carry out ammonolysis reaction. When the pH of the resulting mixed solution was 10, the solution was allowed to stand for aging for 0.75 h. Then the supernatant was removed. The resulting precipitate slurry was washed with pure water several times and then dried to obtain zirconium hydroxide precursor.

[0055] (3) The zirconium hydroxide precursor was calcined at 900°C in air for 2 hours to obtain the monoclinic zirconium oxide nanopowder.

[0056] Example 4

[0057] A method for preparing monoclinic zirconia nanopowder, the process flow diagram of which is shown below. Figure 1 As shown, the specific preparation steps are as follows:

[0058] (1) Weigh 22g of raw material zirconium oxychloride octahydrate, measure 110mL of water, and completely dissolve zirconium oxychloride octahydrate in water to obtain zirconium oxychloride aqueous solution; place zirconium oxychloride aqueous solution in 150mL reactor for hydrothermal reaction, the reactor filling degree is 80%, the reaction temperature is 140℃, and the reaction time is 16h; after the reaction is completed, cool to room temperature and let stand for precipitation for 0.5h.

[0059] (2) After the reaction solution was settled in step (1), analytical grade ammonia (concentration of 25 wt%) was added to carry out ammonolysis reaction. When the pH of the resulting mixed solution was 8, the solution was allowed to stand for 1 hour. Then the supernatant was removed. The resulting precipitate was washed with pure water several times and then dried to obtain zirconium hydroxide precursor.

[0060] (3) The zirconium hydroxide precursor was calcined at 950°C in air for 2 hours to obtain the monoclinic zirconium oxide nanopowder.

[0061] Example 5

[0062] A method for preparing monoclinic zirconia nanopowder, the process flow diagram of which is shown below. Figure 1 As shown, the specific preparation steps are as follows:

[0063] (1) Weigh 23g of raw material zirconium oxychloride octahydrate, measure 69mL of water, and completely dissolve zirconium oxychloride octahydrate in water to obtain zirconium oxychloride aqueous solution; place zirconium oxychloride aqueous solution in 100mL reactor for hydrothermal reaction, the reactor filling degree is 80%, the reaction temperature is 150℃, and the reaction time is 14h; after the reaction is completed, cool to room temperature and let stand for precipitation for 0.75h.

[0064] (2) After the reaction solution was settled in step (1) and settled, analytical grade ammonia (concentration of 25 wt%) was added to carry out ammonolysis reaction. When the pH of the resulting mixed solution was 9, the solution was allowed to stand for 0.5 h and then the supernatant was removed. The resulting precipitate was washed with pure water several times and then dried to obtain zirconium hydroxide precursor.

[0065] (3) The zirconium hydroxide precursor was calcined at 850°C for 4 hours in air to obtain the monoclinic zirconium oxide nanopowder.

[0066] Comparative Example 1

[0067] A method for preparing zirconium oxide powder, compared with Example 1, differs in step (2) in that the pH of the mixed solution is adjusted to 7 via ammonolysis, while the rest remains the same. The specific preparation steps are as follows:

[0068] (1) Weigh 18g of raw material zirconium oxychloride octahydrate, measure 72mL of water, and completely dissolve zirconium oxychloride octahydrate in water to obtain zirconium oxychloride aqueous solution; place zirconium oxychloride aqueous solution in 100mL reactor for hydrothermal reaction, the reactor filling degree is 80%, the reaction temperature is 150℃, and the reaction time is 16h; after the reaction is completed, cool to room temperature and let stand for 1h to precipitate.

[0069] (2) After the reaction solution was settled in step (1) and precipitation was completed, analytical grade ammonia (concentration of 28 wt%) was added to carry out ammonolysis reaction. When the pH of the resulting mixed solution was 7, the solution was allowed to stand for aging for 0.75 h. Then the supernatant was removed. The resulting precipitate slurry was washed with pure water several times and then dried to obtain zirconium hydroxide precursor.

[0070] (3) The zirconium hydroxide precursor was calcined at 900°C for 3 hours in air to obtain the zirconium oxide powder.

[0071] Comparative Example 2

[0072] A method for preparing zirconium oxide powder, compared with Example 1, involves reducing the calcination temperature in step (3) to 800℃, while the rest remains the same. The specific preparation steps are as follows:

[0073] (1) Weigh 18g of raw material zirconium oxychloride octahydrate, measure 72mL of water, and completely dissolve zirconium oxychloride octahydrate in water to obtain zirconium oxychloride aqueous solution; place zirconium oxychloride aqueous solution in 100mL reactor for hydrothermal reaction, the reactor filling degree is 80%, the reaction temperature is 150℃, and the reaction time is 16h; after the reaction is completed, cool to room temperature and let stand for 1h to precipitate.

[0074] (2) After the reaction solution was settled in step (1), analytical grade ammonia (concentration of 28 wt%) was added to carry out ammonolysis reaction. When the pH of the resulting mixed solution was 8.5, the solution was allowed to stand for 0.75 h. Then the supernatant was removed. The resulting precipitate was washed with pure water several times and then dried to obtain zirconium hydroxide precursor.

[0075] (3) The zirconium hydroxide precursor was calcined at 800°C for 3 hours in air to obtain the zirconium oxide powder.

[0076] Comparative Example 3

[0077] A method for preparing zirconium oxide powder, compared with Example 1, involves reducing the temperature of the hydrothermal reaction in step (1) to 130°C, while the rest remains the same. The specific preparation steps are as follows:

[0078] (1) Weigh 18g of raw material zirconium oxychloride octahydrate, measure 72mL of water, and completely dissolve zirconium oxychloride octahydrate in water to obtain zirconium oxychloride aqueous solution; place zirconium oxychloride aqueous solution in 100mL reactor for hydrothermal reaction, the reactor filling degree is 80%, the reaction temperature is 130℃, and the reaction time is 16h; after the reaction is completed, cool to room temperature and let stand for 1h to precipitate.

[0079] (2) After the reaction solution was settled in step (1), analytical grade ammonia (concentration of 28 wt%) was added to carry out ammonolysis reaction. When the pH of the resulting mixed solution was 8.5, the solution was allowed to stand for 0.75 h. Then the supernatant was removed. The resulting precipitate was washed with pure water several times and then dried to obtain zirconium hydroxide precursor.

[0080] (3) The zirconium hydroxide precursor was calcined at 900°C for 3 hours in air to obtain the zirconium oxide powder.

[0081] Comparative Example 4

[0082] A method for preparing zirconium oxide powder, compared with Example 1, directly employs a one-step hydrothermal ammonolysis reaction. The specific preparation steps are as follows:

[0083] (1) Weigh 18g of raw material zirconium oxychloride octahydrate, measure 72mL of water, and completely dissolve zirconium oxychloride octahydrate in water to obtain zirconium oxychloride aqueous solution; place the zirconium oxychloride aqueous solution in a 150mL reactor for hydrothermal reaction. During the hydrothermal reaction, add analytical grade ammonia water (concentration of 28wt%) to adjust the pH of the mixed solution to 8.5, the reactor filling degree is 80%, the reaction temperature is 150℃, and the reaction time is 16h; after the reaction is completed, cool to room temperature and let it stand for 1h to precipitate. Then remove the supernatant, and wash the obtained precipitate slurry with pure water several times and dry it to obtain zirconium hydroxide precursor.

[0084] (2) The zirconium hydroxide precursor was calcined at 900°C for 3 hours in air to obtain the zirconium oxide powder.

[0085] The particle size and Cl of the zirconium oxide powder obtained in the above examples and comparative examples are as follows: - The content was tested, and the results are shown in Table 1 below:

[0086] Table 1. Detection results of zirconium oxide powder

[0087]

[0088]

[0089] The comparison between Comparative Example 1 and the Example shows that a pH below 8 in the ammonolysis reaction leads to a significant increase in product particle size and Cl. - The content increased significantly. This may be because excessively low pH can lead to incomplete ammonolysis and easily cause the gelation reaction of zirconium oxychloride, ultimately resulting in a decrease in product particle size and Cl content. - Increased content. A comparison of Comparative Example 2 and the Example shows that lower precursor calcination temperature leads to a decrease in product particle size, Cl... - The content did not increase significantly, but it still exceeded the application range of lithium battery cathode material additives. This indicates that the appropriate calcination temperature of this invention makes it easier to prepare powders with suitable particle size, and is also more conducive to the decomposition and removal of impurities. The comparison results between Comparative Example 3 and the Examples show that excessively low hydrothermal reaction temperatures lead to a significant increase in product particle size and Cl... - The content increased significantly. This may be because the lower temperature of the hydrothermal reaction leads to a slower nucleation rate, giving precursor particles more time to grow, resulting in larger precursor particle size. This increases the entrainment and encapsulation of chloride ions by the precipitate, ultimately leading to a larger product particle size and higher chloride content. - Increased content. A comparison of Example 4 and the embodiment shows that using a one-step hydrothermal ammonolysis reaction results in a larger product particle size, Cl... -While the content did not increase significantly, it still exceeded the application range of lithium battery cathode material additives. This invention first precipitates most of the zirconium ions through a hydrothermal reaction, and then precipitates the remaining residual zirconium ions through an ammonolysis reaction. This allows for control of the precipitation rate, resulting in finer precipitate particles and reduced entrainment and encapsulation of chloride ions by the precipitate. Consequently, it reduces the particle size and chloride ion content of the final zirconium oxide nanopowder product, improving product quality.

[0090] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A method for preparing monoclinic zirconia nanopowder, characterized in that, The preparation steps include the following: (1) Dissolve zirconium oxychloride octahydrate in water to obtain zirconium oxychloride aqueous solution, then place it in a hydrothermal reactor and heat it to 140~160℃ for hydrothermal reaction. After the reaction is completed, cool it to room temperature and let it stand to precipitate. (2) Add ammonia to the reaction solution in step (1) to make the pH of the mixed solution 8~10 for ammonolysis reaction, let it stand and age, completely precipitate the residual zirconium ions, separate the precipitate, wash and dry it to obtain zirconium hydroxide precursor; (3) The zirconium hydroxide precursor obtained in step (2) is calcined at 850~950℃ in air to obtain the monoclinic zirconium oxide nanopowder.

2. The method for preparing monoclinic zirconia nanopowder according to claim 1, characterized in that, The mass ratio of zirconium oxychloride octahydrate to water in step (1) is 1:3~5.

3. The method for preparing monoclinic zirconia nanopowder according to claim 1, characterized in that, In the hydrothermal reaction process described in step (1), the filling degree of the hydrothermal reactor is 70~85%.

4. The method for preparing monoclinic zirconia nanopowder according to claim 1, characterized in that, The hydrothermal reaction time in step (1) is 12-16 hours; the settling time is 0.5-1 hour.

5. The method for preparing monoclinic zirconia nanopowder according to claim 1, characterized in that, The mass concentration of the ammonia water mentioned in step (2) is 25~28%.

6. The method for preparing monoclinic zirconia nanopowder according to claim 1, characterized in that, The settling and aging time in step (2) is 0.5~1h.

7. The method for preparing monoclinic zirconia nanopowder according to claim 1, characterized in that, The washing mentioned in step (2) refers to washing multiple times with pure water.

8. The method for preparing monoclinic zirconia nanopowder according to claim 1, characterized in that, The heat preservation and calcination treatment in step (3) takes 2 to 4 hours.

9. The method for preparing monoclinic zirconia nanopowder according to claim 1, characterized in that, The monoclinic zirconium oxide nanopowder described in step (3) has a D50 particle size of <0.5 μm and Cl - Content < 200 ppm.

Images