Preparation method of sulfide solid electrolyte ultrafine powder material with high air stability

Abstract

The invention discloses a preparation method of a high-air-stability sulfide solid electrolyte superfine powder material, which comprises the following steps: dispersing sulfide solid electrolyte powder in a low-polarity mixed solution for ball milling, and then sequentially performing vacuum drying and screening to obtain the sulfide solid electrolyte superfine powder material, the low-grade mixed solution comprises a first solvent, a second solvent and a third solvent; the first solvent does not react with the sulfide solid electrolyte and can play a dispersion role; the second solvent does not react with the first solvent, but slightly reacts with the sulfide solid electrolyte to promote the solid electrolyte and the low-grade mixed solution to form turbid liquid; the third solvent does not react with the first solvent and the second solvent, and meanwhile, the third solvent can perform surface modification on the sulfide solid electrolyte to enable the sulfide solid electrolyte to have hydrophobicity. Sulfide solid electrolyte powder (D50 is less than or equal to 100 microns) is modified and refined into ultrafine powder (D50lt; 1 [mu] m).

Description

Technical Field

[0001] The present invention relates to the technical field of lithium-ion battery sulfide electrolytes, and particularly to a preparation method of a lithium-ion sulfide solid electrolyte material with improved air stability and particle size refinement. Background Art

[0002] With the rapid development of new energy vehicles and portable electronic devices, the demand for batteries with high energy density and high safety is increasing day by day. All-solid-state batteries have become a research hotspot in the battery field due to their advantages such as high safety, high energy density, and long cycle life. As one of the core materials of all-solid-state batteries, sulfide solid electrolytes have high lithium-ion conductivity and good mechanical properties, but their poor air stability and interface matching with electrode materials limit their applications.

[0003] Sulfide electrolytes are prone to react with moisture and oxygen in the air, resulting in the collapse of the crystal structure and the decline of ionic conductivity performance. Researchers have developed various methods, such as doping soft acids in sulfide electrolytes or coating superhydrophobic materials on the electrolyte surface and other strategies to reduce their reactivity with water, thereby improving their air stability, etc. The paper Surface molecular engineering to enable processing of sulfide solid electrolytes in humid ambient air published by Ping Liu et al. in Nature Communications discloses the adoption of a reversible surface modification strategy, using long-chain alkyl mercaptan (1-undecyl mercaptan) to chemically adsorb on the surface of sulfide solid electrolytes to form a hydrophobic protective layer, thereby playing a role in protecting the electrolyte powder. In addition, the paper Water-stable sulfide solid electrolyte membranes directly applicable in all-solid-state batteries enabled by superhydrophobic Li published by Fan Wu et al. in Advanced Energy Materials +-conducting protection layer A super-hydrophobic lithium-ion conductive protection layer is publicly developed. The hydrophobic silicon source TEOS (tetraethyl orthosilicate) and PFDTES (perfluorodecyltriethoxysilane) molecules are used to hydrolyze and condense the surface of LATP oxide solid electrolyte nanoparticles, and then sprayed on the surface of the sulfide solid electrolyte membrane to improve the air stability of the sulfide electrolyte membrane. However, this treatment process will reduce the ionic conductivity of the LPSC membrane. In addition, this method is only applicable to the surface modification of the membrane, not to improving the air stability of the sulfide solid electrolyte powder material, and its use scenarios are limited.

[0004] On the other hand, the particle size of the sulfide electrolyte sintered material after one crushing is large, which will lead to a decrease in the contact area between the electrolyte and the electrode, thereby increasing the interfacial impedance of the battery and reducing the overall performance of the battery. In order to solve this problem, researchers have been exploring methods for refining sulfide solid electrolytes. Although traditional methods such as mechanical ball milling and air flow milling can reduce the particle size to a certain extent, they are often accompanied by problems such as high energy consumption and particle agglomeration. In recent years, wet ball milling technology has gradually attracted attention. The patent with publication number CN118020116A uses a wet crushing method to prepare a sulfide-based solid electrolyte powder with a particle size of less than 1 μm. Although the particle size of the electrolyte is less than 1 μm, there is currently no report by researchers on ultrafine powder sulfide solid electrolytes with high air stability and high conductivity.

[0005] Current research often focuses on improving the air stability or particle size distribution of sulfide electrolytes. The preparation of ultrafine powder sulfide solid electrolytes with high air stability and high conductivity is still a technical problem that needs to be solved. Developing a comprehensive modification method that can both improve the air stability of sulfide electrolytes and refine their particle size will help improve the overall performance and application prospects of all-solid-state batteries. Summary of the invention

[0006] The purpose of the present invention is to provide a preparation method of lithium ion sulfide solid electrolyte material with improved air stability and fine particle size, ball milling process and later vacuum drying process, to modify and refine sulfide solid electrolyte powder (D50≤100μm) into ultrafine powder (D50<1μm) with high air stability. Ultrafine powder sulfide electrolyte with high air stability can increase the contact area with electrode materials and improve the stability of lithium metal interface to achieve the cycle stability of all-solid-state lithium metal battery, and can reduce the strict requirements of sulfide all-solid-state battery manufacturing on the environment, simplify the production process, reduce production costs, and further realize commercialization.

[0007] The technical solution adopted by the present invention to solve the above technical problems is:

[0008] Preparation method of high-altitude air-stable sulfide solid electrolyte ultrafine powder material, comprising the following steps: dispersing sulfide solid electrolyte powder in a low-polarity mixed solution for ball milling, and then successively performing vacuum drying and sieving to obtain the sulfide solid electrolyte ultrafine powder material;

[0009] The low-polarity mixed solution includes a first solvent, a second solvent, and a third solvent;

[0010] The first solvent does not react with the sulfide solid electrolyte and can play a dispersing role;

[0011] The second solvent does not react with the first solvent, but reacts weakly with the sulfide solid electrolyte, promoting the formation of a suspension of the solid electrolyte and the low-polarity mixed solution and improving the grinding efficiency;

[0012] The third solvent does not react with either the first solvent or the second solvent, and at the same time the third solvent can perform surface modification on the sulfide solid electrolyte to make it hydrophobic.

[0013] Preferably, the specific step of dispersing the sulfide solid electrolyte in the low-polarity mixed solution is: under a protective atmosphere, adding the sulfide solid electrolyte and the third solvent into the mixed solution composed of the first solvent and the second solvent simultaneously for dispersion.

[0014] Preferably, the first solvent is at least one of o-xylene, p-xylene, toluene, n-hexane, n-heptane, and octane.

[0015] Preferably, the second solvent is an ether solvent and / or an ester solvent. The ether solvent is at least one of diethyl ether, dipropyl ether, dibutyl ether, and dipentyl ether; the ester solvent is at least one of ethyl acetate, dimethyl carbonate, n-propyl acetate, and n-butyl acetate.

[0016] Preferably, the third solvent is at least one of 1-undecanethiol, aluminum trifluoromethanesulfonate, sodium trifluoromethanesulfonate, and pentafluorophenylboron.

[0017] Preferably, the mass ratio of the sulfide solid electrolyte to the third solution is 1-10:1, the mass ratio of the third solvent to the mixed solution of the first solvent and the second solvent combination is 1:5-100, and the mass ratio of the first solvent and the second solvent is 1-50:1.

[0018] Preferably, the specific conditions of the protective atmosphere are that the nitrogen N 2 or argon Ar content ≥ 99.99%, and the oxygen O 2 content ≤ 0.01 ppm, and the moisture H 2The O content is ≤ 0.01 ppm. The diameter range of the grinding balls is 0.3 - 5 mm, the ball-to-material ratio is 5 - 35:1, the ball milling method is one of mechanical ball milling, horizontal rolling milling, and vibratory ball milling, and the rotation speed is 200 - 1000 r / min.

[0019] Preferably, the temperature of vacuum drying is 50°C - 300°C, and the heat preservation time is 10 h - 30 h.

[0020] Preferably, the sulfide electrolyte can be a glass-ceramic obtained by heating a sulfide solid electrolyte above the crystallization temperature, or a sulfide with a crystal structure, specifically Li 3 PS 4 crystal structure, Li 4 P 2 S 6 crystal structure, Li 7 PS 6 crystal structure, Li 7 P 3 S 11 crystal structure, Li 10 GeP 2 S 12 crystal structure.

[0021] Preferably, the particle size range of the initially used sulfide solid electrolyte powder is D50 ≤ 100 μm, and the particle size range of the prepared ultrafine powder material of the sulfide solid electrolyte is D50 < 1 μm.

[0022] In the preparation method of the high air-stability sulfide solid electrolyte ultrafine powder material of the present invention, the combined use of three solvents plays a key role. The physical and chemical properties of each solvent contribute to improving the performance of the sulfide solid electrolyte material, and through reasonable ratio control, an ideal surface modification effect, dispersion effect, and hydrophobicity can be obtained. The following are the specific effects of the three solvents in the preparation process:

[0023] The first solvent is mainly used to disperse the sulfide solid electrolyte. Through the wetting effect of the solvent on the surface of the solid electrolyte, the inter-particle interaction force is reduced, ensuring its uniform distribution in the solution and avoiding particle agglomeration. The selected first solvents, such as o-xylene, toluene, n-hexane, etc., have low polarity, good compatibility with the sulfide solid electrolyte, and can effectively reduce the electrostatic force, van der Waals force and other interactions between particles, and can better disperse the particles and avoid agglomeration. The dispersion effect of this solvent can prevent the re-agglomeration phenomenon caused by the decrease in particle size and the gradual increase in specific surface area.

[0024] The role of the second solvent in the present invention is to slightly react with the surface of the sulfide solid electrolyte particles, and this solvent does not react with the first solvent. The second solvent is usually an ether or ester solvent (such as diethyl ether, dipropyl ether, ethyl acetate, dimethyl carbonate, etc.). These solvents have moderate polarity and can have weak interactions with the surface of the sulfide solid electrolyte. This interaction helps to improve the surface state of the electrolyte particles, form a suspension of the solid electrolyte in the solution, avoid adhesion or accumulation during the ball milling process, thereby ensuring the refinement and homogenization of the sulfide solid electrolyte particles, promoting the surface uniformity of the particles, enhancing the grinding efficiency, and facilitating the obtaining of sub-micron grade ultrafine powders.

[0025] The main role of the third solvent is to provide hydrophobicity to the sulfide solid electrolyte particles. The third solvent can act on the surface of the sulfide solid electrolyte physically or chemically to make its surface hydrophobic. This property enables the electrolyte particles to have higher stability in air, reduces the reaction with moisture and oxygen, and prevents the hydrolysis or oxidation reaction of the sulfide electrolyte. For example, using solvents such as 1-undecanethiol, aluminum trifluoromethanesulfonate, sodium trifluoromethanesulfonate, etc., can form a hydrophobic protective layer on the particle surface, significantly enhancing the tolerance of the particles in a humid environment. This hydrophobic modification plays a crucial role in improving the stability of the material in air and preventing the influence of moisture on the electrolyte.

[0026] The combination of the three solvents plays a complementary role in the preparation process. Each solvent, through its specific chemical and physical properties, synergistically improves the surface properties, dispersibility, and stability of the sulfide solid electrolyte. The finally prepared ultrafine powder material has higher air stability and excellent electrochemical performance.

[0027] Compared with the prior art, the advantages of the present invention are as follows:

[0028] 1. The present invention uses a simple one-step wet ball milling process to improve the air stability of the sulfide solid electrolyte, and at the same time has the effect of particle size refinement. The ultrafine powder sulfide solid electrolyte with high air stability can increase the contact area with the electrode material and improve the stability of the lithium metal interface, thereby significantly improving the cycle stability of the all-solid-state lithium metal battery.

[0029] 2. The preparation process of the present invention is simple, which can simplify the production process and the product quality is controllable. Detailed Embodiments

[0030] The technical solutions of the present invention will be described clearly and completely below. Obviously, the described embodiments are some embodiments of the present invention, rather than all embodiments.

[0031] Example 1

[0032] In the glove box, weigh out 8 g of LPSC (D50 ≤ 100 μm) electrolyte powder and 8 g of 1-undecanethiol, and disperse them simultaneously in 80 g of xylene solvent and 5 g of dimethyl carbonate solvent in a low-polarity mixed solution. Transfer it to a ball milling jar, add 160 g of zirconia grinding balls with a diameter of 1 mm to the ball milling jar, and ball mill at a rotation speed of 400 r / min for 12 h. After sufficient ball milling, transfer the ball milling jar to a vacuum drying oven in the glove box, vacuum dry at 70 °C for 12 h, and then perform ball material screening with a 500-mesh sieve to obtain the LPSC electrolyte ultrafine powder material.

[0033] Those skilled in the art should understand that the diameter range of the grinding balls, the ball-to-material ratio, the rotation speed, etc. can be adjusted according to actual needs. In this embodiment, the diameter range of the grinding balls is preferably 0.5 - 2 mm, and the ball-to-material ratio is preferably 5 - 35:1; after batching, high-speed ball milling is carried out, and the rotation speed is preferably 200 - 1000 r / min. The ball milling method can be mechanical ball milling, horizontal rolling milling, or vibratory ball milling.

[0034] Example 2

[0035] In the glove box, weigh out 8 g of LPSC (D50 ≤ 100 μm) electrolyte powder and 8 g of aluminum trifluoromethanesulfonate, and disperse them simultaneously in 80 g of xylene solvent and 5 g of dimethyl carbonate solvent in a low-polarity mixed solution. Transfer it to a ball milling jar, add 160 g of zirconia grinding balls with a diameter of 1 mm to the ball milling jar, and ball mill at a rotation speed of 400 r / min for 12 h. After sufficient ball milling, transfer the ball milling jar to a vacuum drying oven in the glove box, vacuum dry at 70 °C for 12 h, and then perform ball material screening with a 500-mesh sieve to obtain the LPSC electrolyte ultrafine powder material.

[0036] Example 3

[0037] In the glove box, weigh out 8 g of LPSC (D50 ≤ 100 μm) electrolyte powder and 8 g of 1-undecanethiol, and disperse them simultaneously in 80 g of n-heptane solution and 5 g of dimethyl carbonate solvent in a low-polarity mixed solution. Transfer it to a ball milling jar, add 160 g of zirconia grinding balls with a diameter of 1 mm to the ball milling jar, and ball mill at a rotation speed of 400 r / min for 12 h. After sufficient ball milling, transfer the ball milling jar to a vacuum drying oven in the glove box, vacuum dry at 70 °C for 12 h, and then perform ball material screening with a 500-mesh sieve to obtain the LPSC electrolyte ultrafine powder material.

[0038] Example 4

[0039] In the glove box, 8 g of LPSC (D50 ≤ 100 μm) electrolyte powder and 8 g of 1-undecanethiol were respectively and simultaneously dispersed in a low-polarity mixed solution of 80 g of n-heptane solvent and 5 g of n-butyl ether solvent, transferred to a ball milling jar, 160 g of zirconia grinding balls with a diameter of 1 mm were added to the ball milling jar, ball milled at a rotation speed of 400 r / min for 12 h. After sufficient ball milling, the ball milling jar was transferred to a vacuum drying oven in the glove box, vacuum dried at 70 °C for 12 h, and then screened with a 500-mesh sieve to obtain the LPSC electrolyte ultrafine powder material.

[0040] Example 5

[0041] In the glove box, 8 g of LPSC (D50 ≤ 100 μm) electrolyte powder and 8 g of 1-undecanethiol were respectively and simultaneously dispersed in a low-polarity mixed solution of 80 g of xylene solvent and 5 g of n-butyl ether solvent, transferred to a ball milling jar, 160 g of zirconia grinding balls with a diameter of 1 mm were added to the ball milling jar, ball milled at a rotation speed of 400 r / min for 12 h. After sufficient ball milling, the ball milling jar was transferred to a vacuum drying oven in the glove box, vacuum dried at 70 °C for 12 h, and then screened with a 500-mesh sieve to obtain the LPSC electrolyte ultrafine powder material.

[0042] Example 6

[0043] In the glove box, 80 g of LPSC (D50 ≤ 100 μm) electrolyte powder and 8 g of 1-undecanethiol were respectively and simultaneously dispersed in a low-polarity mixed solution of 50 g of xylene solvent and 50 g of dimethyl carbonate solvent, transferred to a ball milling jar, 160 g of zirconia grinding balls with a diameter of 1 mm were added to the ball milling jar, ball milled at a rotation speed of 400 r / min for 12 h. After sufficient ball milling, the ball milling jar was transferred to a vacuum drying oven in the glove box, vacuum dried at 70 °C for 12 h, and then screened with a 500-mesh sieve to obtain the LPSC electrolyte ultrafine powder material.

[0044] Example 7

[0045] In the glove box, 40 g of LPSC (D50 ≤ 100 μm) electrolyte powder and 8 g of 1-undecanethiol were respectively and simultaneously dispersed in a low-polarity mixed solution of 39 g of xylene solvent and 1 g of dimethyl carbonate solvent, transferred to a ball milling jar, 160 g of zirconia grinding balls with a diameter of 1 mm were added to the ball milling jar, ball milled at a rotation speed of 400 r / min for 12 h. After sufficient ball milling, the ball milling jar was transferred to a vacuum drying oven in the glove box, vacuum dried at 70 °C for 12 h, and then screened with a 500-mesh sieve to obtain the LPSC electrolyte ultrafine powder material.

[0046] Comparative Example 1

[0047] In the glove box, 8 g of LPSC (D50 ≤ 100 μm) electrolyte was dispersed in a low-polarity mixed solution of 80 g of xylene solution and 5 g of dimethyl carbonate solvent, transferred to a ball mill jar. 160 g of zirconia grinding balls with a diameter of 1 mm were added to the ball mill jar, and ball milled at a rotation speed of 400 r / min for 12 h. After sufficient ball milling, the ball mill jar was transferred to a vacuum drying oven in the glove box and vacuum dried at 70 °C for 12 h. Then, screening of the ball material was carried out with a 500-mesh sieve to obtain the LPSC electrolyte powder material.

[0048] Comparative Example 2

[0049] In the glove box, 8 g of LPSC (D50 ≤ 100 μm) electrolyte and 8 g of tetraethyl orthosilicate were simultaneously dispersed in a low-polarity mixed solution of 80 g of xylene solution and 5 g of dimethyl carbonate solvent, transferred to a ball mill jar. 160 g of zirconia grinding balls with a diameter of 1 mm were added to the ball mill jar, and ball milled at a rotation speed of 400 r / min for 12 h. After sufficient ball milling, the ball mill jar was transferred to a vacuum drying oven in the glove box and vacuum dried at 70 °C for 12 h. Then, screening of the ball material was carried out with a 500-mesh sieve to obtain the LPSC electrolyte powder material.

[0050] Comparative Example 3

[0051] In the glove box, 8 g of LPSC (D50 ≤ 100 μm) electrolyte and 8 g of 1-undecanethiol were simultaneously dispersed in 80 g of xylene solution, transferred to a ball mill jar. 160 g of zirconia grinding balls with a diameter of 1 mm were added to the ball mill jar, and ball milled at a rotation speed of 400 r / min for 12 h. After sufficient ball milling, the ball mill jar was transferred to a vacuum drying oven in the glove box and vacuum dried at 70 °C for 12 h. Then, screening of the ball material was carried out with a 500-mesh sieve to obtain the LPSC electrolyte powder material.

[0052] Comparative Example 4

[0053] In the glove box, 8 g of LPSC (D50 ≤ 100 μm) electrolyte and 8 g of 1-undecanethiol were simultaneously dispersed in 80 g of n-heptane solution, transferred to a ball mill jar. 160 g of zirconia grinding balls with a diameter of 1 mm were added to the ball mill jar, and ball milled at a rotation speed of 400 r / min for 12 h. After sufficient ball milling, the ball mill jar was transferred to a vacuum drying oven in the glove box and vacuum dried at 70 °C for 12 h. Then, screening of the ball material was carried out with a 500-mesh sieve to obtain the LPSC electrolyte powder material.

[0054] Comparative Example 5

[0055] In the glove box, weigh 8 g of LPSC (D50 ≤ 100 μm) electrolyte powder and 8 g of 1-undecanethiol, and disperse them simultaneously in 80 g of xylene solvent and 5 g of dimethyl carbonate solvent in a low-polarity mixed solution. Transfer it to a ball mill jar, add 160 g of zirconia grinding balls with a diameter of 0.3 mm to the ball mill jar, and ball mill for 12 h at a rotation speed of 400 r / min. After sufficient ball milling, transfer the ball mill jar to a vacuum drying oven in the glove box, vacuum dry at 70 °C for 12 h, and then sieve the ball material with a 500-mesh sieve to obtain the LPSC electrolyte ultrafine powder material.

[0056] Comparative Example 6

[0057] In the glove box, weigh 8 g of LPSC (D50 ≤ 100 μm) electrolyte powder and 8 g of 1-undecanethiol, and disperse them simultaneously in 80 g of xylene solvent and 5 g of dimethyl carbonate solvent in a low-polarity mixed solution. Transfer it to a ball mill jar, add 160 g of zirconia grinding balls with a diameter of 5 mm to the ball mill jar, and ball mill for 12 h at a rotation speed of 400 r / min. After sufficient ball milling, transfer the ball mill jar to a vacuum drying oven in the glove box, vacuum dry at 70 °C for 12 h, and then sieve the ball material with a 500-mesh sieve to obtain the LPSC electrolyte ultrafine powder material.

[0058] Comparative Example 7

[0059] In the glove box, weigh 8 g of LPSC (D50 ≤ 100 μm) electrolyte powder and 8 g of 1-undecanethiol, and disperse them simultaneously in 80 g of xylene solvent and 5 g of dimethyl carbonate solvent in a low-polarity mixed solution. Transfer it to a ball mill jar, add 40 g of zirconia grinding balls with a diameter of 1 mm to the ball mill jar, and ball mill for 12 h at a rotation speed of 400 r / min. After sufficient ball milling, transfer the ball mill jar to a vacuum drying oven in the glove box, vacuum dry at 70 °C for 12 h, and then sieve the ball material with a 500-mesh sieve to obtain the LPSC electrolyte ultrafine powder material.

[0060] Comparative Example 8

[0061] In the glove box, weigh 8 g of LPSC (D50 ≤ 100 μm) electrolyte powder and 8 g of 1-undecanethiol, and disperse them simultaneously in 80 g of xylene solvent and 5 g of dimethyl carbonate solvent in a low-polarity mixed solution. Transfer it to a ball mill jar, add 350 g of zirconia grinding balls with a diameter of 1 mm to the ball mill jar, and ball mill for 12 h at a rotation speed of 400 r / min. After sufficient ball milling, transfer the ball mill jar to a vacuum drying oven in the glove box, vacuum dry at 70 °C for 12 h, and then sieve the ball material with a 500-mesh sieve to obtain the LPSC electrolyte ultrafine powder material.

[0062] Performance test:

[0063] 1. Test the ionic conductivity of the electrolyte. Test method: Take 100 mg of sulfide electrolyte and press it into a disc with a diameter of 10 mm under 380 MPa. Use carbon-coated aluminum foil as the blocking electrode and test the electrochemical impedance spectroscopy with the test conditions of 10 MHz to 1 Hz.

[0064] 2. Test the air stability of the electrolyte. Place 1 g of sulfide electrolyte in a dew point drying chamber at -40 °C for 12 hours and then test the ionic conductivity of the electrolyte.

[0065] 3. Test the particle size of the electrolyte. Take 1 g of sulfide electrolyte and test and analyze it with a Baxter particle size analyzer.

[0066] Table 1

[0067]

[0068] The results of Comparative Examples 1 and 2 and Example 1 show that neither adding no third solvent nor adding an inappropriate solvent (tetraethyl orthosilicate) achieved a good moisture resistance effect, and the ionic conductivity decreased severely. On the contrary, adding the third solvent (1-undecanethiol) had a significant effect, and the electrolyte had higher air stability.

[0069] The results of Comparative Examples 3 and 4 and Example 1 show that using a single solvent could not effectively disperse and refine the sulfide electrolyte due to the lack of a synergistic effect, resulting in a relatively large particle size of the powder.

[0070] The results of Comparative Examples 5 and 6 and Example 1 show that when the diameter of the grinding balls is too small, the kinetic energy is too small, and the impact force on the electrolyte powder is insufficient, resulting in an insignificant refinement effect; when the diameter of the grinding balls is too large, the gap between the grinding balls is too large, resulting in insufficient grinding of the powder and a relatively large particle size of the powder.

[0071] The results of Comparative Examples 7 and 8 and Example 1 show that when the number of grinding balls is too small, the collision probability between the balls will be greatly reduced, and secondly, the kinetic energy is small, and the impact force on the powder per unit time is insufficient, resulting in an insignificant refinement effect; when the number of grinding balls is too large, although the particle size refinement effect can be achieved, due to the excessive number of ball milling beads, more powder adheres to the surface of the grinding balls, greatly reducing the material collection rate.

[0072] Through the synergistic effect of the combination of the three solvents in the present invention, it is specifically manifested in:

[0073] Dispersibility and stability: The first solvent ensures good dispersion of the sulfide solid electrolyte in the solution, prevents particle agglomeration, and optimizes the ball milling process; the second solvent modifies the particle surface through a weak chemical reaction to improve the stability and performance of the particles; the third solvent imparts hydrophobicity to the particle surface, thereby improving the stability of the material in air.

[0074] Performance improvement: Through a reasonable solvent ratio, the three solvents can act synergistically to maximize the improvement of the surface properties of the sulfide solid electrolyte, enabling it to maintain good stability during subsequent vacuum drying and screening processes, and ultimately obtaining an ultra-fine powder material with high air stability, uniform particle size, and good conductivity.

[0075] Optimizing the particle structure: During the refinement and hydrophobization processes, the selective reaction of the solvent can optimize the microstructure of the particles, increasing the mechanical strength and stability of the electrolyte, thus contributing to its stability during long-term use.

[0076] In summary, the combination of the three solvents plays a complementary role in the preparation process. Each solvent, through its specific chemical and physical properties, synergistically improves the surface properties, dispersibility, and stability of the sulfide solid electrolyte. The ultimately prepared ultra-fine powder material has higher air stability and optimized electrochemical performance.

[0077] The purpose of preparing the ultra-fine solid electrolyte material in this invention is to refine the particle size of the sulfide electrolyte to D50 < 1 μm. This ultra-fine powder electrolyte can significantly increase the contact area with the electrode material, thereby improving the efficiency and performance of the battery.

[0078] Simplifying the production process: The one-step wet ball milling process adopted in this invention can not only improve the air stability of the sulfide solid electrolyte but also refine its particle size, reducing the complex steps in the production process and simplifying the process flow. Compared with traditional multi-step preparation methods, this invention significantly reduces the production difficulty and cost.

[0079] Reducing environmental requirements: Since this invention uses a low-polarity solvent system for ball milling treatment, the preparation process does not require extreme environmental conditions (such as high temperature, low temperature, etc.). Therefore, it can reduce the strict environmental requirements, lower the production cost, and make the process more environmentally friendly.

[0080] Strong adaptability: The electrolyte provided in this invention is not limited to a certain type of sulfide but also includes sulfides with various crystal structures (such as Li 3 PS 4 、Li 4 P 2 S 6 、Li 7 PS 6 、Li 7 P 3 S 11 、Li 10 GeP 2 S 12 etc.). Therefore, it has wide applicability in different types of all-solid-state lithium batteries.

[0081] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing ultrafine powder material of sulfide solid electrolyte with high air stability, characterized in that: The following steps are involved: The sulfide solid electrolyte powder is dispersed in a low-polarity mixed solution and ball-milled, and then vacuum-dried and sieved in sequence to obtain a sulfide solid electrolyte ultrafine powder material; The low-grade mixed solution includes a first solvent, a second solvent and a third solvent; The first solvent does not react with the sulfide solid electrolyte and can play a dispersing role; The second solvent does not react with the first solvent, but reacts weakly with the sulfide solid electrolyte, causing the solid electrolyte and the low-grade mixed solution to form a suspension; The third solvent does not react with the first solvent and the second solvent, and the third solvent can modify the surface of the sulfide solid electrolyte to make it hydrophobic.

2. The method for preparing the ultrafine powder material of sulfide solid electrolyte with high air stability according to claim 1, characterized in that: The specific steps of dispersing the sulfide solid electrolyte in the low-polarity mixed solution are: under a protective atmosphere, adding the sulfide solid electrolyte and the third solvent to the mixed solution composed of the first solvent and the second solvent respectively and simultaneously for dispersion.

3. The method for preparing the ultrafine powder material of sulfide solid electrolyte with high air stability according to claim 1, characterized in that: The first solvent is at least one of o-xylene, p-xylene, toluene, n-hexane, n-heptane and octane.

4. The method for preparing the ultrafine powder material of sulfide solid electrolyte with high air stability according to claim 1, characterized in that: The second solvent is an ether solvent and / or an ester solvent, the ether solvent is at least one of ethyl ether, dipropyl ether, dibutyl ether, and diamyl ether; the ester solvent is at least one of ethyl acetate, dimethyl carbonate, n-propyl acetate, and n-butyl acetate.

5. The method for preparing the ultrafine powder material of sulfide solid electrolyte with high air stability according to claim 1, characterized in that: The third solvent is at least one of 1-undecanethiol, aluminum trifluoromethanesulfonate, sodium trifluoromethanesulfonate, and pentafluorophenyl boron.

6. The method for preparing the ultrafine powder material of sulfide solid electrolyte with high air stability according to any one of claims 1 to 5, characterized in that: The mass ratio of the sulfide solid electrolyte to the third solution is 1-10:1, the mass ratio of the mixed solution of the third solvent, the first solvent and the second solvent is 1:5-100, and the mass ratio of the first solvent to the second solvent is 1-50:

1.

7. The method for preparing the ultrafine powder material of sulfide solid electrolyte with high air stability according to claim 2, characterized in that: The specific conditions of the protective atmosphere are that the nitrogen N2 or argon Ar content is ≥ 99.99%, the oxygen O2 content is ≤ 0.01ppm, and the water H2O content is ≤ 0.01ppm; The diameter of the grinding balls ranges from 0.3 to 5 mm, the ball-to-material ratio is 5 to 35:1, the ball milling method is one of mechanical ball milling, horizontal roller milling, and vibration ball milling, and the rotation speed is 200-1000 r / min.

8. The method for preparing the ultrafine powder material of sulfide solid electrolyte with high air stability according to claim 1, characterized in that: The vacuum drying temperature is 50°C-300°C, and the insulation time is 10h-30h.

9. The method for preparing the ultrafine powder material of sulfide solid electrolyte with high air stability according to claim 1, characterized in that: The sulfide electrolyte may be a glass ceramic obtained by heating a sulfide solid electrolyte to a temperature above the crystallization temperature, or may be a sulfide having a crystal structure, specifically a Li3PS4 crystal structure, a Li4P2S6 crystal structure, a Li7PS6 crystal structure, a Li7P3S 11 Crystal structure, Li 10 GeP2S 12 Crystal structure.

10. The method for preparing the ultrafine powder material of sulfide solid electrolyte with high air stability according to claim 1, characterized in that: The particle size range of the sulfide solid electrolyte powder initially used is D50≤100 μm, and the particle size range of the prepared sulfide solid electrolyte ultrafine powder material is D50<1 μm.

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