High-dispersity superfine solid electrolyte material and preparation method thereof

Abstract

The invention discloses a high-dispersity superfine solid electrolyte material and a preparation method thereof.The preparation method comprises the steps that firstly, solid electrolyte coarse powder is dispersed in deionized water, then a high-flash-point and weak-polarity solvent is added into the deionized water, the solid electrolyte powder is promoted to be fully mixed with the deionized water and the weak-polarity solvent in a blending and fine grinding mode, and the high-dispersity superfine solid electrolyte material is obtained; and the weak-polarity mixed slurry is formed. In the process, the particle aggregation phenomenon is inhibited by utilizing a solvent polarity regulation and control mechanism, and the uniformity of the slurry is ensured. And then, carrying out desolvation treatment on the weak-polarity mixed slurry. In the desolvation process, a solute and a solvent in the slurry can be separated to form a wet blocky material. Then, the wet blocky materials are dried, and dried soft agglomerated particles are obtained; and finally, carrying out jet milling treatment on the soft agglomerated particles, further refining the particle size, and finally obtaining high-dispersion nanoscale solid electrolyte powder.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of lithium ion batteries, in particular to a high-dispersity ultrafine solid electrolyte material and a preparation method thereof. BACKGROUND

[0002] Oxide solid electrolytes are a class of ceramic materials with unique crystal structures. Due to their high ionic conductivity and excellent chemical stability, they have become important research objects in the field of solid-state batteries. These materials not only exhibit good ionic conductivity at room temperature, but also have high mechanical strength, which can effectively inhibit the growth of lithium dendrites, thereby significantly improving the safety and cycle life of the battery. As the industry's demand for the performance of oxide solid electrolytes continues to increase, especially the demand for high dispersity of the powder particle size, the industrialization of high-dispersity nanometer oxide solid electrolytes has attracted much attention. Therefore, how to improve the preparation efficiency of nanometer oxide solid electrolytes and reduce the production cost has become a key problem to be solved in the new energy industry.

[0003] In the preparation process of nanometer solid electrolyte powder, traditional processes often use organic alcohol as a solvent. However, the high cost and flammability of organic alcohol solvents not only increase the cost pressure of industrial production, but also pose a potential threat to operational safety. In addition, some oxide solid electrolytes, such as lithium lanthanum zirconium oxide (LLZO) and lanthanum lithium titanate (LLTO), have a lithium-rich phase on their surface that can react with water and carbon dioxide in the air to form low-activity substances such as lithium carbonate and lithium hydroxide. These products not only significantly increase the alkalinity of the electrolyte surface, but also cause a significant decline in its electrochemical performance, thereby severely hindering the large-scale production and commercial application of these materials.

[0004] To solve the above problems, the present application uses deionized water instead of organic alcohol as a solvent. However, the strong polar nature of water can significantly enhance the interaction between powder particles, exacerbating particle agglomeration, thereby limiting the optimization of powder performance. To inhibit particle agglomeration and reduce residual alkali generated by the reaction, the present application introduces an appropriate amount of weakly polar solvent into the deionized water system. By adjusting the polarity of the solvent, the interparticle interaction force is effectively weakened, and the oxide electrolyte that is prone to reaction is protected, thereby improving the dispersity and electrochemical performance of the powder, providing a feasible solution for the industrial production of oxide solid electrolytes.

[0005] Existing patents and literature include patent JP 2010108882A, which uses organic alcohols as solvents to obtain nanoscale oxide solid electrolyte powder through spray drying. However, this process is costly, poses safety hazards, and requires attention to environmental impact. Patent CN202410697555.X reports the preparation of nanoscale oxide solid electrolyte powder via a water-based dispersion method. This method requires strict control of the pH reaction conditions of the precursor raw materials, making the process difficult to control and hindering large-scale production. In summary, while existing technologies can prepare nanoscale oxide solid electrolytes to some extent, they still suffer from drawbacks such as complex preparation processes, long cycles, high costs, environmental pollution, and safety hazards. Summary of the Invention

[0006] In view of the shortcomings of the prior art, the present invention provides a process method that combines ease of operation, high production capacity, high preparation efficiency, and stable preparation of solid electrolyte powder with high dispersibility and ultrafine particle size. This method can not only significantly improve the comprehensive performance of solid electrolyte materials, but also reduce manufacturing costs through large-scale production. At the same time, the use of deionized water makes the production process safer, thus providing technical support for the practical application of solid electrolyte technology.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows: In the preparation process of nanoscale solid electrolyte powder, coarse solid electrolyte powder is first dispersed in deionized water. Then, a high flash point, weakly polar solvent is added, and a blending and fine grinding method is used to ensure thorough mixing of the solid electrolyte powder with the deionized water and weakly polar solvent, forming a "weakly polar mixed slurry." During this process, a solvent polarity control mechanism is used to suppress particle agglomeration and ensure the uniformity of the slurry. Subsequently, the weakly polar mixed slurry undergoes desolvation treatment. During desolvation, the solute and solvent in the slurry separate, forming wet lumps. Next, the wet lumps are dried to obtain soft agglomerated particles. Finally, the soft agglomerated particles are subjected to air jet milling to further refine the particle size, ultimately obtaining highly dispersed, nanoscale solid electrolyte powder.

[0008] As a preferred technical solution, the solid electrolyte coarse powder is selected from one or more of lithium lanthanum zirconium oxide (LLZO), lithium lanthanum titanate (LLTO), lithium titanium aluminum phosphate (LATP), lithium germanium aluminum phosphate (LAGP), lithium titanium silicon aluminum phosphate (LATSP), and lithium zirconium silicon phosphate (LZSP); the mass ratio of the solid electrolyte coarse powder to deionized water is 1:1 to 1:5.

[0009] As a preferred technical solution, the volume ratio of the weakly polar solvent to deionized water is 1:9 to 9:1.

[0010] As a preferred technical solution, the weakly polar solvent is selected from one or more combinations of ethylene glycol, polyethylene glycol, tetramethylbenzene, methylnaphthalene, diphenyl ether, and polydimethylsiloxane.

[0011] As a preferred technical solution, the initial average particle size D50 of the solid electrolyte coarse powder is 3μm to 7μm.

[0012] As a preferred technical solution, the fine grinding method in step S2 is divided into sand milling, roller milling, and planetary ball milling; the desolvation method in step S3 is divided into vacuum filtration, forced air drying, centrifugal drying, vacuum drying, spray drying, and freeze drying.

[0013] As a preferred technical solution, the drying method in step S4 is divided into blower drying, vacuum drying, and nitrogen-protected drying, and the average particle size D50 of the dried soft agglomerates is 0.6μm to 0.8μm.

[0014] As a preferred technical solution, the drying temperature in step S4 is 60℃~130℃.

[0015] As a preferred technical solution, the air pressure of the airflow pulverizer in step S4 is 0.6MPa to 0.8MPa.

[0016] As a preferred technical solution, the grinding time is 1h to 5h, and the grinding linear speed is 25 to 30m / s.

[0017] Compared with the prior art, this application has the following technical effects: 1. By adding a high flash point, weakly polar solvent to the water-based system provided by this invention, and by controlling the solvent polarity to weaken the interaction forces between particles, the problem of easy agglomeration and poor dispersion of ultrafine solid electrolyte slurry after drying is solved, resulting in highly dispersible nano-electrolyte materials. Moreover, this method is applicable to the preparation of different solid electrolyte powders and has a wide range of applications.

[0018] 2. This invention introduces a weakly polar solvent to reduce the overall polarity of the system, thereby forming a more stable dispersion environment and avoiding the problem of easy agglomeration of traditional aqueous particles.

[0019] 3. This invention effectively reduces the overall polarity of the system by introducing a weakly polar solvent into the water-based system, thereby reducing the formation of residual alkali on the surface of the oxide solid electrolyte. This improvement significantly reduces the alkalinity of the electrolyte surface, improves the chemical stability and electrochemical performance of the material, and solves the performance degradation problem caused by residual alkali formation in traditional methods.

[0020] 4. Compared to other traditional preparation methods, this method is highly adaptable to the automation and large-scale requirements of industrial production. Furthermore, the use of desolvation treatment makes the production process safer, more efficient, and more stable, enabling the large-scale production of highly dispersed, nanoscale solid electrolyte powders. Studies have found that production efficiency has increased by 30%, while total costs have decreased by approximately 50%. Attached Figure Description

[0021] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0022] Figure 1 These are electron microscope images of the solid electrolyte materials obtained in the various embodiments of the present invention. Detailed Implementation

[0023] The following description is intended to disclose the invention and enable those skilled in the art to implement it. The preferred embodiments described below are merely examples, and other obvious variations will occur to those skilled in the art.

[0024] Example 1: This example provides a method for preparing a highly dispersible ultrafine solid electrolyte material. Crude LATSP (lithium titanium silicon aluminum phosphate) powder is mixed with deionized water at a mass ratio of 1:2 and added to a sand mill. Simultaneously, a weakly polar solvent, ethylene glycol, is added, making the mass ratio of ethylene glycol to deionized water 1:9, forming a water-based, weakly polar mixed slurry system. The particle size D50 of the crude LATSP powder is 5 ± 0.6 μm.

[0025] The mixed slurry containing coarse raw powder was milled. Milling conditions were 4 h and a linear velocity of 25 m / s, yielding a homogeneous slurry with a unimodal distribution and an average particle size D50 of 0.15 μm. The resulting weakly polar mixed slurry was centrifuged to separate the solvent, resulting in wet lumps. These wet lumps were then placed in a forced-air drying oven and dried at 80°C to obtain soft, agglomerated dry particles. Finally, the dried particles were subjected to air jet milling to obtain highly dispersible ultrafine LATSP solid electrolyte powder with a unimodal distribution and an average particle size D50 of 0.151 μm.

[0026] Example 2: In this example, crude lithium aluminum titanium phosphate (LATP) solid electrolyte powder was mixed with deionized water at a mass ratio of 1:3 and added to a sand mill. Simultaneously, a weakly polar solvent, tetramethylbenzene, was added to achieve a tetramethylbenzene to deionized water mass ratio of 1:8, forming a water-based, weakly polar mixed slurry system. The particle size D50 of the crude LATP powder was 5 ± 0.6 μm.

[0027] A homogeneous slurry with a single-peak particle size distribution and an average particle size D50 of 0.3 μm was obtained after sand milling for 4 hours at 25 m / s. The resulting weakly polar slurry was then filtered to separate the solvent, yielding wet lumps. These wet lumps were then placed in a forced-air drying oven and dried at 60°C to obtain soft-agglomerated dried particles. These soft-agglomerated dried particles were then subjected to air jet milling to obtain highly dispersible ultrafine LATP powder with a single-peak particle size distribution and an average particle size D50 of 0.312 μm.

[0028] Example 3: In this example, crude lithium lanthanum zirconium oxide (LLZO) solid electrolyte powder was mixed with deionized water at a mass ratio of 1:4 and added to a sand mill. Simultaneously, a weakly polar solvent, polydimethylsiloxane, was added, bringing the mass ratio of polydimethylsiloxane to deionized water to 1:7, forming a water-based, weakly polar mixed slurry system. The particle size D50 of the crude LLZO powder was 5 ± 0.6 μm.

[0029] A homogeneous slurry with a single-peak particle size distribution and an average particle size D50 of 0.3 μm was obtained after sand milling for 4 hours at 25 m / s. The resulting weakly polar slurry was then filtered to separate the solvent, yielding wet lumps. These wet lumps were then placed in a forced-air drying oven and dried at 80°C to obtain soft-agglomerated dried particles. These soft-agglomerated dried particles were then subjected to air jet milling to obtain highly dispersible ultrafine LLZO powder with a single-peak particle size distribution and an average particle size D50 of 0.322 μm, free of lithium carbonate and lithium hydroxide second phases.

[0030] Example 4: Crude LAGP (lithium aluminum germanium phosphate) solid electrolyte powder was mixed with deionized water at a mass ratio of 1:5 and added to a sand mill. Simultaneously, a weakly polar solvent, polyethylene glycol-200, was added to achieve a mass ratio of 1:6 with deionized water, forming a water-based, weakly polar mixed slurry system. The particle size D50 of the crude LAGP powder was 5 ± 0.6 μm.

[0031] A uniform slurry with a single-peak particle size distribution and an average particle size D50 of 0.600 μm was obtained under sand milling conditions of 4 h and 25 m / s. Spray drying conditions included centrifugal atomization at 380 Hz, an outlet temperature of 110 °C, and forced-air drying at 70 °C. After air jet milling, highly dispersible ultrafine LAGP powder with a single-peak particle size distribution and an average particle size D50 of 0.609 μm was obtained.

[0032] Comparative Example 1, without the participation of weakly polar solvents: Coarse LATSP powder and deionized water were mixed at a mass ratio of 1:2 and added to a sand mill. The particle size D50 of the coarse LATSP powder was 5 ± 0.6 μm. Subsequently, sand milling was performed for 4 hours at a linear speed of 25 m / s to ensure uniform mixing, resulting in a homogeneous slurry with a single-peak distribution and an average particle size D50 of 0.15 μm. The slurry was then centrifuged to separate the solvent, yielding wet lumps. These lumps were then placed in a forced-air drying oven and dried at 80°C to obtain soft, agglomerated dry particles. Finally, the dried powder was subjected to air jet milling to obtain ultrafine LATSP electrolyte powder with a single-peak distribution and an average particle size D50 of 0.423 μm. This is significantly larger than that of Example 1, indicating significant powder agglomeration in the absence of weakly polar solvents.

[0033] Comparative Example 2, without the participation of weakly polar solvents: Crude LATP powder and deionized water were mixed at a mass ratio of 1:3 and added to a sand mill. The particle size D50 of the crude LATP powder was 5 ± 0.6 μm. Subsequently, sand milling was performed for 4 hours at a linear speed of 25 m / s to ensure uniform mixing, resulting in a homogeneous slurry with a single-peak distribution and an average particle size D50 of 0.30 μm. The slurry was then filtered to separate the solvent, yielding wet lumps. These wet lumps were then placed in a forced-air drying oven and dried at 60°C to obtain soft, agglomerated dry particles. Finally, the dried powder was subjected to air jet milling to obtain ultrafine LATP electrolyte powder with a single-peak distribution and an average particle size D50 of 0.502 μm. This is significantly larger than that of Example 2.

[0034] Comparative Example 3: In this embodiment, crude lithium lanthanum zirconium oxide (LLZO) solid electrolyte powder was mixed with deionized water at a mass ratio of 1:4 and added to a sand mill. The particle size D50 of the crude LLZO powder was 5 ± 0.6 μm. Subsequently, sand milling was performed for 4 hours at a linear velocity of 25 m / s to ensure uniform mixing, resulting in a homogeneous slurry with a single-peak distribution and an average particle size D50 of 0.30 μm. The slurry was then filtered to separate the solvent, yielding wet lumps. These wet lumps were then placed in a forced-air drying oven and dried at 80°C to obtain soft, agglomerated dry particles. Finally, the dried powder was subjected to air jet milling to obtain ultrafine lithium lanthanum zirconium oxide (LLZO) electrolyte powder with a single-peak distribution and an average particle size D50 of 0.601 μm, containing a second phase of lithium carbonate and lithium hydroxide.

[0035] Comparative Example 4, without the participation of weakly polar solvents: Coarse LAGP powder and deionized water were mixed at a mass ratio of 1:5 and added to a sand mill. The particle size D50 of the coarse germanium aluminum phosphate LAGP powder was 5 ± 0.6 μm. Subsequently, sand milling was performed for 4 hours at a linear velocity of 25 m / s to ensure uniform mixing, resulting in a homogeneous slurry with a single-peak distribution and an average particle size D50 of 0.60 μm. Next, the slurry was sent to a spray dryer for spray drying, with an inlet centrifugal frequency of 380 Hz and an outlet temperature of 110 °C, followed by forced-air drying at 70 °C. Finally, the dried powder was subjected to air jet milling to obtain ultrafine germanium aluminum phosphate LAGP electrolyte powder with a single-peak distribution and an average particle size D50 of 0.903 μm.

[0036] This invention employs a mixed dispersion system consisting of deionized water and a high flash point, weakly polar solvent, which demonstrates significant technical effects in the preparation of ultrafine solid electrolyte powders.

[0037] The basic principle of this invention lies in dispersing a solid electrolyte in a mixture of a weakly polar solvent and deionized water. By modulating the solvent's polarity, the electrostatic attraction and hydrogen bonding between particles are weakened, thereby enhancing the adsorption stability of the solvent on the particle surface and effectively reducing the risk of powder agglomeration. Simultaneously, the introduction of the weakly polar solvent can significantly inhibit the formation of residual alkali on the solid electrolyte surface, reducing the problems of increased surface alkalinity and decreased electrochemical performance caused by residual alkali. Based on this, by combining processes such as refining, desolvation, drying, and airflow milling, the controllable preparation of nanoscale solid electrolyte powders can be achieved.

[0038] Compared with traditional pure water systems combined with desolvation, drying, and air jet milling, the powder prepared by this invention exhibits higher dispersion stability and lower agglomeration rate under the same particle size conditions, which can significantly improve the compaction density and ionic conductivity of solid electrolytes. Furthermore, the use of high flash point solvents effectively reduces the risk of fire. This process not only possesses good safety and process continuity but is also more suitable for large-scale industrial production.

[0039] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed invention.

Claims

1. A method for preparing a high dispersibility ultrafine solid electrolyte material, characterized by, The method comprises the following steps: S1, mixing solid electrolyte coarse powder, deionized water and weak polar solvent to form a weak polar mixed slurry; S2, performing fine grinding treatment on the mixed slurry; S3, performing desolvation on the fine-ground slurry to separate the solvent and obtain a wet blocky material; S4, performing drying treatment on the wet blocky material to obtain soft agglomerated particles; S5, performing air flow crushing on the soft agglomerated particles to obtain the high-dispersibility ultra-fine solid electrolyte material.

2. The production method according to claim 1, characterized by, The solid electrolyte coarse powder is selected from one or more of lithium lanthanum zirconium oxide (LLZO), lithium lanthanum titanate (LLTO), lithium aluminum titanium phosphate (LATP), lithium aluminum germanium phosphate (LAGP), lithium aluminum titanium silicon phosphate (LATSP) and lithium zirconium silicon phosphate (LZSP); the mass ratio of the solid electrolyte coarse powder to deionized water is 1:1-1:

5.

3. The preparation method according to claim 1, characterized in that, The volume ratio of the weak polar solvent to deionized water is 1:9-9:

1.

4. The method of claim 1, wherein, The weak polar solvent is selected from one or more of ethylene glycol, polyethylene glycol, tetramethylbenzene, methylnaphthalene, diphenyl ether and polydimethylsiloxane.

5. The preparation method according to claim 1, characterized in that, The initial average particle size D50 of the solid electrolyte coarse powder is 3-7 μm.

6. The method of claim 1, wherein, The fine grinding mode in step S2 is sand grinding, roll grinding or planetary ball grinding; the desolvation mode in step S3 is suction filtration, air drying, centrifugal drying, vacuum drying, spray drying or freeze drying.

7. The preparation method according to claim 1, characterized in that, The drying mode in step S4 is air drying, vacuum drying or nitrogen protection drying; the average particle size D50 of the soft agglomerated particles after drying is 0.6-0.8 μm; the drying temperature in step S4 is 60-130 °C.

8. The method of claim 1, wherein, The air flow pressure in step S5 is 0.6-0.8 MPa.

9. The preparation method according to claim 6, characterized in that, The sand grinding time is 1-5 h, and the sand grinding linear speed is 25-30 m / s.

10. A highly dispersible ultrafine solid-state electrolyte material, characterized by, The method is prepared by the preparation method in any one of claims 1-9.

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