Method for preparing sulfide solid electrolyte with refined particle size, sulfide solid electrolyte, solid-state battery

Abstract

This application discloses a method for preparing a sulfide solid electrolyte with refined particle size, a sulfide solid electrolyte, and a solid-state battery. The preparation method includes preparing a mixed solution comprising a nonpolar main solvent, a first stabilizer, and a second stabilizer. The first stabilizer comprises a silane coupling agent containing a thiol group, and the second stabilizer comprises a nonpolar fluorobenzene derivative. Coarse particles of the pre-prepared sulfide solid electrolyte are dispersed in the mixed solution and ball-milled to obtain a uniformly dispersed electrolyte slurry. The electrolyte slurry is then subjected to solid-liquid separation to collect the solid material. After drying, the solid material is heat-treated under an inert atmosphere to obtain a sulfide solid electrolyte with refined particle size. The sulfide solid electrolyte prepared by this application has small and uniform particle size distribution, and its air stability against water and oxygen corrosion is greatly enhanced, meeting the requirements for the industrialization of all-solid-state batteries.

Description

Technical Field

[0001] This application relates to the field of battery technology, and in particular to a method for preparing a sulfide solid electrolyte with refined particle size, a sulfide solid electrolyte, and a solid battery. Background Technology

[0002] With the global energy structure transitioning towards green and low-carbon development, electric vehicles and large-scale energy storage systems are experiencing explosive growth, placing unprecedented demands on the energy density and safety performance of rechargeable batteries. All-solid-state lithium batteries, by using a non-flammable inorganic solid electrolyte instead of the liquid electrolyte in traditional lithium-ion batteries, fundamentally solve the battery safety problem and possess the potential to break through the energy density ceiling, and are widely considered the ultimate solution for next-generation power and energy storage batteries. Among various solid electrolyte systems, sulfide solid electrolytes have the highest room-temperature ionic conductivity, reaching up to 10⁻⁶. -2 With a flow rate in the range of S / cm and excellent mechanical ductility, it can form a tight contact with electrode materials under relatively low pressure, and is therefore regarded as one of the most promising technical routes.

[0003] However, the industrialization of sulfide solid electrolytes still faces many technical challenges. Currently, the mainstream preparation method for sulfide solid electrolytes is solid-state synthesis, including high-energy mechanical ball milling and high-temperature sintering processes. Electrolyte powders prepared by these methods generally suffer from defects such as large particle size, wide particle size distribution, and irregular morphology. This leads to a significant reduction in the effective contact area between electrolyte particles, increasing the grain boundary resistance for lithium ion transport within the electrolyte layer. Furthermore, it is difficult to form a large-area, low-resistance close contact with the electrode active material, resulting in extremely high electrode / electrolyte interface resistance, which severely restricts the rate performance, volumetric energy density, and cycle life of all-solid-state batteries.

[0004] To address the issue of coarse particle size in sulfide solid electrolytes, the scientific and industrial communities have conducted numerous explorations. Among these, liquid-phase methods (such as liquid-phase synthesis), solvent-assisted grinding, or dispersion processes are considered among the most effective pathways for particle size refinement. By dispersing precursors or solid-phase synthesis products in a solvent, particle refinement and homogenization can be achieved. However, existing liquid-phase techniques typically rely on highly polar protic solvents (such as ethanol and isopropanol) as dispersion media. The active hydroxyl groups (-OH) in these solvent molecules undergo violent acid-base neutralization reactions with lithium ions (Lewis acids) and sulfide anions (Lewis bases) in the sulfide electrolyte. This chemical erosion irreversibly damages the glass-ceramic network structure of the electrolyte, leading to a sharp decrease in its intrinsic ionic conductivity.

[0005] Therefore, there is an urgent need to develop a preparation method that can achieve particle size refinement of sulfide solid electrolytes. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the purpose of this application is to provide a method for preparing sulfide solid electrolytes with fine particle size, sulfide solid electrolytes, and solid batteries, which can produce sulfide solid electrolytes with fine particle size and high ionic conductivity.

[0007] To achieve one or more of the above objectives or other objectives, the first aspect of this application provides a method for preparing a sulfide solid electrolyte with a refined particle size, the method comprising:

[0008] A mixed solution is prepared, the mixed solution comprising a nonpolar main solvent, a first stabilizer, and a second stabilizer; wherein the first stabilizer comprises a silane coupling agent containing a thiol group, and the second stabilizer comprises a nonpolar fluorobenzene derivative;

[0009] The pre-prepared coarse particles of sulfide solid electrolyte are dispersed in the mixed solution and ball-milled to obtain a uniformly dispersed electrolyte slurry.

[0010] The electrolyte slurry is subjected to solid-liquid separation to collect the solid substances;

[0011] After drying the solid material, it is heat-treated under an inert atmosphere to obtain a sulfide solid electrolyte with a finer particle size.

[0012] Furthermore, before the step of dispersing the pre-prepared coarse particles of sulfide solid electrolyte in the mixed solution and performing ball milling to obtain a uniformly dispersed electrolyte slurry, the method further includes:

[0013] The precursor raw materials are weighed according to the stoichiometric ratio and mixed evenly in an inert atmosphere to obtain precursor powder. The precursor raw materials include lithium sulfide and phosphorus pentasulfide.

[0014] The precursor powder was calcined and then cooled to room temperature before being crushed to obtain coarse particles of the sulfide solid electrolyte.

[0015] Furthermore, the nonpolar primary solvent includes at least one of hexane, octane, heptane, o-xylene, m-xylene, and p-xylene.

[0016] Further, the first stabilizer comprises at least one of 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 3-mercaptopropylmethyldimethoxysilane, and bis-(3-triethoxysilylpropyl)-disulfide.

[0017] Furthermore, the second stabilizer includes at least one of hexafluorobenzene, perfluorotrimethylbenzene, 1,3,5-trifluorobenzene, and perfluorobiphenyl.

[0018] Furthermore, in the nonpolar primary solvent, the volume ratio of the first stabilizer to the second stabilizer is (1-10):(1-5):1.

[0019] Further, the step of dispersing the pre-prepared coarse particles of sulfide solid electrolyte in the mixed solution and ball-milling them to obtain a uniformly dispersed electrolyte slurry includes:

[0020] Weigh the coarse particles of the sulfide solid electrolyte and the mixed solution at a mass ratio of 1:(1~20), place them in a ball mill jar for ball milling, and mill at a speed of 200 rpm~600 rpm for 1 h~9 h to obtain a uniformly dispersed electrolyte slurry.

[0021] Further, the step of drying the solid material and then heat-treating it under an inert atmosphere to obtain a sulfide solid electrolyte with a fine particle size includes:

[0022] The solid material is dried at 60℃~120℃ for 6h~18h to obtain the dried product;

[0023] The dried product is subjected to heat treatment under an inert atmosphere. The heat treatment temperature is 80℃~250℃ and the heat treatment duration is 1h~6h.

[0024] The second aspect of this application provides a sulfide solid electrolyte, which is prepared by the above-described method for preparing a sulfide solid electrolyte with refined particle size.

[0025] Furthermore, the median particle size D50 of the sulfide solid electrolyte is 0.5 μm to 1.5 μm.

[0026] A third aspect of this application provides a solid-state battery, comprising a sulfide solid-state electrolyte prepared by the above-described method for preparing a sulfide solid-state electrolyte with refined particle size.

[0027] This application provides a method for preparing sulfide solid electrolytes with refined particle size, the sulfide solid electrolyte itself, and a solid-state battery. A non-polar main solvent provides a low-reactivity dispersion environment, effectively avoiding the chemical corrosion of the electrolyte by traditional protic solvents. A first stabilizer generates a ceramic-like protective layer framework through chemical anchoring and cross-linking reactions. A second stabilizer optimizes the microstructure of the protective layer through physical intercalation and hydrophobic interactions. Under the synergistic effect of these three components, a dense and stable protective layer is formed on the surface of the refined sulfide solid electrolyte, and the strength and density of the protective layer are far superior to the modification effect of a single stabilizer. The final prepared sulfide solid electrolyte not only has a small and uniform particle size distribution, but also retains its intrinsic ionic conductivity completely, and its air stability against water and oxygen corrosion is significantly enhanced, meeting the comprehensive performance requirements of electrolytes for the industrialization of all-solid-state batteries. Attached Figure Description

[0028] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0029] Figure 1 Comparison of XRD patterns of sulfide solid electrolytes prepared in Example 1 and Comparative Example 1;

[0030] Figure 2 The AC impedance test results of the sulfide solid electrolytes prepared in Examples 1-6 and Comparative Example 1 are compared.

[0031] Figure 3 For the particle size comparison of Example 1 and Comparative Example 1, wherein Figure 3 (a) is a particle size distribution diagram of coarse sulfide solid electrolyte particles. Figure 3 (b) is a particle size distribution diagram of the sulfide solid electrolyte prepared in Example 1. Figure 3 (c) is a particle size distribution diagram of the sulfide solid electrolyte prepared in Comparative Example 1;

[0032] Figure 4 The XRD patterns of the sulfide solid electrolytes prepared in Example 1 and Comparative Example 1 after being placed in air for 30 minutes are compared. Detailed Implementation

[0033] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used herein in the specification of the application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application; the terms "comprising" and "having," and any variations thereof, in the specification, claims, and foregoing drawings of this application, are intended to cover non-exclusive inclusion. The terms "first," "second," etc., in the specification, claims, or foregoing drawings of this application are used to distinguish different objects, not to describe a particular order.

[0034] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0035] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings.

[0036] This application provides a method for preparing a sulfide solid electrolyte with a fine particle size, the preparation method comprising:

[0037] S1: Prepare a mixed solution, the mixed solution comprising a nonpolar main solvent, a first stabilizer, and a second stabilizer; wherein the first stabilizer comprises a silane coupling agent containing a thiol group, and the second stabilizer comprises a nonpolar fluorobenzene derivative;

[0038] S2: Disperse the pre-prepared coarse particles of sulfide solid electrolyte in the mixed solution and ball mill them to obtain a uniformly dispersed electrolyte slurry.

[0039] S3: Perform solid-liquid separation on the electrolyte slurry and collect the solid substances;

[0040] S4: After drying the solid material, heat treatment is carried out under an inert atmosphere to obtain a sulfide solid electrolyte with a fine particle size.

[0041] In this embodiment, in step S1 above, a nonpolar main solvent without active functional groups (such as hydroxyl, amino, etc.) is selected as the dispersion substrate. The first stabilizer and the second stabilizer are added to the nonpolar main solvent and magnetically stirred for 10 min to 60 min to ensure that the components are fully mixed and form a homogeneous and stable mixed solution. The nonpolar main solvent does not possess active protons (-OH), and its polarity matches that of the sulfide electrolyte, thereby avoiding violent acid-base reactions with lithium ions and sulfide anions in the electrolyte. The nonpolar main solvent disperses and wets the coarse electrolyte particles in subsequent steps only through physical actions (such as van der Waals forces and solvation effects) without destroying its chemical structure, and the intrinsic ionic conductivity is fully preserved. The first stabilizer and the second stabilizer are uniformly distributed in the mixed solution and are used to adsorb and react on the newly formed surface of the electrolyte particles in subsequent steps to modify the surface of the electrolyte particles, forming a dense, ultrathin protective layer that does not hinder lithium ion transport. At the same time, the protective layer can also effectively block water molecules from contacting the active substances inside the particles.

[0042] In step S2 above, coarse sulfide solid electrolyte particles prepared using conventional methods are added to the mixed solution at a preset solid-liquid mass ratio. The mixture is then placed in a ball mill for ball milling to physically break down and refine the coarse particles. During ball milling, the coarse particles continuously break down and generate new active surfaces. The first and second stabilizers in the mixed solution are simultaneously adsorbed and act on the newly generated active surfaces of the electrolyte as the particles are refined, forming a preliminary modified layer. The thiol groups (-SH) of the first stabilizer interact strongly with the ionic sites on the electrolyte surface through coordination or chemical bonding, achieving chemical anchoring. Simultaneously, the second stabilizer adsorbs onto the electrolyte surface and forms a weak interaction with the first stabilizer molecules. This step refines the particle size through ball milling while simultaneously performing preliminary surface modification of the electrolyte. The chemical anchoring effect of the first stabilizer effectively inhibits the agglomeration of particles after refinement due to excessive surface activity, while the physical adsorption of the second stabilizer initially blocks contact between external water and oxygen and the electrolyte surface.

[0043] In step S3 above, conventional solid-liquid separation methods such as centrifugation and filtration are used to process the ball-milled electrolyte slurry. The separated solid material consists of refined electrolyte particles loaded with the first and second stabilizers. The separation process is carried out in a low-water-oxygen environment (such as a glove box).

[0044] In step S4 above, the separated solid material is placed in a drying device and dried at a preset temperature for a certain period of time to completely remove the residual non-polar main solvent adsorbed on the particle surface. After drying, the solid particles are transferred to a tube furnace or box furnace and subjected to low-temperature heat treatment under an inert atmosphere (such as argon or nitrogen). By controlling the heating rate and holding time, the first and second stabilizers are promoted to form a protective layer on the refined sulfide solid electrolyte surface.

[0045] In this process, the thiol group (-SH) in the first stabilizer has strong reactivity and can undergo strong chemical interaction with the electrolyte surface to achieve stable anchoring. The alkoxy group at the silane end undergoes hydrolysis and condensation reaction during heat treatment to form a continuous and dense three-dimensional Si-O-Si covalent cross-linked network, thereby constructing a chemically anchored and structurally dense ceramic-like protective layer on the electrolyte surface. Meanwhile, the fluorobenzene derivative molecules of the second stabilizer are directionally inserted into the pores and intermolecular spaces of the siloxane network. On the one hand, the superhydrophobicity and chemical inertness of fluorine atoms endow the protective layer with excellent water and oxygen barrier capabilities. On the other hand, the nonpolar properties of the fluorobenzene derivative and the siloxane network work synergistically to further fill the network gaps of the protective layer, optimize the microstructure of the protective layer, and simultaneously improve its density and hydrophobic properties.

[0046] In this embodiment, the nonpolar main solvent provides a low-reactivity dispersion environment, effectively avoiding the chemical corrosion of the electrolyte by traditional protic solvents. The first stabilizer generates a ceramic-like protective layer framework through chemical anchoring and cross-linking reactions, while the second stabilizer optimizes the microstructure of the protective layer through physical intercalation and hydrophobic interactions. Under the synergistic effect of these three components, a dense and stable protective layer is formed on the surface of the refined sulfide solid electrolyte, and the strength and density of this protective layer are far superior to the modification effect of a single stabilizer. The final prepared sulfide solid electrolyte not only has a small and uniform particle size distribution, but also retains its intrinsic ionic conductivity completely, and its air stability against water and oxygen corrosion is significantly enhanced, meeting the comprehensive performance requirements of the electrolyte for the industrialization of all-solid-state batteries.

[0047] In some specific embodiments, before step S2, which involves dispersing the pre-prepared coarse particles of sulfide solid electrolyte in the mixed solution and ball milling them to obtain a uniformly dispersed electrolyte slurry, the method further includes:

[0048] S01: Weigh the precursor raw materials according to the stoichiometric ratio and mix them evenly in an inert atmosphere to obtain precursor powder. The precursor raw materials include lithium sulfide and phosphorus pentasulfide.

[0049] S02: The precursor powder is calcined and then cooled to room temperature before being crushed to obtain coarse particles of the sulfide solid electrolyte.

[0050] In this embodiment, in step S01 above, the precursor raw material is weighed according to the chemical composition of the target sulfide solid electrolyte. In some embodiments, the precursor raw material is Li2S and P2S5, and in other embodiments, the precursor raw material is Li2S, P2S5, and LiCl. The above mixing method can be low-speed ball milling, high-speed ball milling, roller milling, etc., with high-speed ball milling being preferred. Exemplarily, the weighed precursor raw material is placed in a mixing device (such as a planetary ball mill or roller mill) under an inert atmosphere, and ball milling is performed in a low-water-oxygen environment. During the ball milling process, the ball-to-material mass ratio is controlled at (10-50):1, the ball diameter is 0.5mm-10mm, the mixing speed is 100rpm-600rpm, and the mixing time is 4h-20h, until a uniformly dispersed precursor powder without obvious agglomeration is obtained.

[0051] In step S02 above, the precursor powder obtained in step S01 is loaded into a high-temperature resistant inert container (such as an alumina crucible or a quartz crucible) and placed in a tube furnace for calcination. During calcination, an inert gas (such as argon or nitrogen) is introduced as a protective gas. The calcination temperature is controlled at 400℃-700℃, the holding time is 2h-10h, and the heating rate is 5℃ / min-10℃ / min to ensure that the precursor undergoes a sufficient solid-phase reaction at high temperature to generate a sulfide electrolyte block with the target crystal structure. After calcination, the electrolyte block is naturally cooled to room temperature and then transferred to a crushing device in a low-water-oxygen environment. It is crushed at a power of 10000rpm-35000rpm for 1-5 times, with each crushing lasting 10s-50s, finally obtaining coarse sulfide solid electrolyte particles with a particle size of 10μm-50μm.

[0052] In some specific embodiments, the nonpolar primary solvent includes at least one of hexane, octane, heptane, o-xylene, m-xylene, and p-xylene. In actual use, it can be used alone or in combination with two or more solvents according to actual process requirements. The selected nonpolar primary solvents do not contain active functional groups (such as hydroxyl and amino groups) or active protons, and are chemically inert, avoiding acid-base reactions or chemical corrosion with lithium ions and sulfide anions in the sulfide electrolyte, ensuring that their intrinsic ionic conductivity is not compromised. Simultaneously, the aforementioned types of nonpolar primary solvents exhibit good dispersibility for the first and second stabilizers, enabling uniform distribution of both stabilizers in the solution. In this embodiment, the nonpolar solvent achieves thorough wetting and dispersion of coarse particles through physical actions such as van der Waals forces and solvation effects, effectively reducing the risk of particle agglomeration during ball milling and improving the uniformity of particle size refinement.

[0053] In some specific embodiments, the first stabilizer includes at least one of 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 3-mercaptopropylmethyldimethoxysilane, and bis-(3-triethoxysilylpropyl)-disulfide. In actual use, it can be used alone or in combination with two or more depending on the specific process requirements. The selected first stabilizers all contain highly active thiol groups (-SH), which can coordinate or chemically bond with ionic sites on the surface of the sulfide electrolyte, achieving strong chemical anchoring and effectively inhibiting secondary agglomeration of particles after ball milling due to excessive surface activity. Simultaneously, the silane-terminal alkoxy groups (methoxy, ethoxy, etc.) contained in their molecular structure can hydrolyze and condense during subsequent heat treatment to form a three-dimensional Si-O-Si covalent cross-linked network, providing a stable framework for the ceramic-like protective layer.

[0054] In some specific embodiments, the second stabilizer includes at least one of hexafluorobenzene, perfluorotrimethylbenzene, 1,3,5-trifluorobenzene, and perfluorobiphenyl. In practical application, it can be used alone or in combination with two or more stabilizers depending on actual process requirements. The selected second stabilizer contains a high proportion of fluorine atoms, possessing both superhydrophobicity and chemical inertness. It can form a highly efficient physical hydrophobic barrier on the electrolyte surface, preventing contact with external water and oxygen. Simultaneously, its nonpolar molecular structure is well-compatible with the nonpolar main solvent and the first stabilizer, allowing for uniform dispersion in the mixed solution. During ball milling, it adsorbs onto the electrolyte surface along with the first stabilizer, forming weak interactions. In subsequent heat treatment stages, the molecules of the second stabilizer can be directionally embedded into the pores and intermolecular spaces of the siloxane cross-linked network. Through the weak interactions between fluorine atoms and the siloxane network, the microstructure of the protective layer is optimized, synergistically constructing a denser and more hydrophobic protective layer with the first stabilizer, significantly improving the long-term air stability of the sulfide electrolyte.

[0055] In some specific embodiments, the volume ratio of the first stabilizer to the second stabilizer in the nonpolar main solvent is (1-10):(1-5):1. Excessive use of the first stabilizer leads to severe cross-linking, forming an excessively thick, dense layer on the surface of the electrolyte particles, hindering lithium-ion transport and severely affecting ionic conductivity. Insufficient use of the first stabilizer prevents the cross-linked products from fully coating the surface of the electrolyte particles, resulting in minimal improvement in air stability. In practical applications, the ratio can be flexibly adjusted within the above range according to process requirements. For example, the volume ratio can be 1:1:1, 5:1:1, 10:1:1, 1:2:1, 5:2:1, 10:2:1, 1:5:1, 5:5:1, 10:5:1, etc. Preferably, the volume ratio of the first stabilizer to the second stabilizer in the nonpolar main solvent is (3-5):(2-3):1.

[0056] In some specific embodiments, step S2, which involves dispersing pre-prepared coarse sulfide solid electrolyte particles in the mixed solution and ball-milling them to obtain a uniformly dispersed electrolyte slurry, includes:

[0057] Weigh the coarse particles of the sulfide solid electrolyte and the mixed solution at a mass ratio of 1:(1~20), place them in a ball mill jar for ball milling, and mill at a speed of 200 rpm~600 rpm for 1 h~9 h to obtain a uniformly dispersed electrolyte slurry.

[0058] In this embodiment, under the aforementioned mass ratio of coarse sulfide solid electrolyte particles to the mixed solution, the coarse particles can be fully wetted and coated by the mixed solution. Exemplarily, the mass ratio can be 1:1, 1:3, 1:5, 1:8, 1:10, 1:12, 1:15, 1:17, 1:20, etc. During ball milling, a ball-to-material mass ratio of (5:30):1 is used, and the size of the milling beads is 0.3mm to 5mm. Under the above ball milling conditions, it can be ensured that the final particles are fine in size and uniformly distributed. During ball milling, the coarse particles are continuously broken down to generate new active surfaces. The first and second stabilizers in the mixed solution can be simultaneously and uniformly adsorbed and act on the newly formed surfaces, achieving simultaneous completion of particle size refinement and preliminary surface modification.

[0059] In some specific embodiments, step S4, which involves drying the solid material and then heat-treating it under an inert atmosphere to obtain a sulfide solid electrolyte with a refined particle size, includes:

[0060] S401: Dry the solid material at 60℃~120℃ for 6h~18h to obtain the dried product;

[0061] S402: The dried product is subjected to heat treatment under an inert atmosphere, the heat treatment temperature is 80℃~250℃, and the heat treatment duration is 1h~6h.

[0062] In this embodiment, step S401 involves removing residual nonpolar main solvent from the solid material under the aforementioned drying process. The drying temperature can be determined based on the nonpolar main solvent, ensuring its removal. For example, the drying temperature can be 60°C, 70°C, 80°C, 90°C, 100°C, 110°C, 120°C, etc., and the drying time can be 6h, 8h, 10h, 12h, 14h, 16h, 18h, etc. In some specific exemplary embodiments, hexane is dried at 60°C~80°C for 6h~0h; heptane, octane, o-xylene, m-xylene, and p-xylene are dried at 100°C~120°C for 10h~18h.

[0063] In step S402 above, at the aforementioned heat treatment temperature, the first stabilizer fully cross-links to form a ceramic-like protective layer framework, while the second stabilizer is directionally embedded into the siloxane network, ultimately constructing a dense and stable composite protective layer. This avoids damaging the electrolyte's bulk structure, resulting in a sulfide solid electrolyte with a median particle size D50 of 0.5 μm to 1.5 μm. For example, the heat treatment temperature can be 80℃, 100℃, 120℃, 150℃, 180℃, 200℃, 230℃, 250℃, etc. In some exemplary embodiments, the first stabilizer is either 3-mercaptopropyltrimethoxysilane or 3-mercaptopropylmethyldimethoxysilane, and the second stabilizer is either hexafluorobenzene or 1,3,5-trifluorobenzene, with a heat treatment temperature of 80°C to 100°C; the first stabilizer is 3-mercaptopropyltriethoxysilane, and the second stabilizer is perfluorotrimethylbenzene, with a heat treatment temperature of 100°C to 150°C; the first stabilizer is bis-(3-triethoxysilylpropyl)-disulfide, and the second stabilizer is perfluorobiphenyl, with a heat treatment temperature of 150°C to 250°C.

[0064] The embodiments of this application also provide a sulfide solid electrolyte, which is prepared by any of the above-mentioned methods for preparing sulfide solid electrolyte with fine particle size. The obtained sulfide solid electrolyte has a small and uniform particle size, its intrinsic ionic conductivity is fully preserved, and its air stability against water and oxygen corrosion is significantly enhanced, which can meet the comprehensive performance requirements of electrolytes for the industrialization of all-solid-state batteries.

[0065] In some specific embodiments, the median particle size D50 of the sulfide solid electrolyte is 0.5 μm to 1.5 μm.

[0066] Embodiments of this application also provide a solid-state battery, including a sulfide solid-state electrolyte prepared by any of the above-described methods for preparing a sulfide solid-state electrolyte with a refined particle size.

[0067] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions of this application will be further described in detail below with reference to the accompanying drawings and several preferred embodiments. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Unless otherwise specified, the test methods in the following embodiments are performed under conventional conditions. Furthermore, the technical features involved in the various embodiments of this application described below can be combined with each other as long as they do not conflict with each other.

[0068] Example 1

[0069] Step 1: Weigh 6.9g of lithium sulfide, 8.3g of phosphorus pentasulfide and 4.8g of lithium chloride, and mix them by ball milling in an inert atmosphere. The ball-to-material ratio is 50:1, the ball diameter is 5mm, the ball milling speed is 500rpm, and the ball milling is carried out for 12h to obtain the precursor powder.

[0070] Step 2: Place the precursor powder into a sealed crucible, place it in a tube furnace, heat it to 500℃ at 2℃ / min and calcine for 8 hours. After cooling to room temperature, crush it three times with a crusher at a speed of 25000rpm / min for 20s each time to obtain coarse particles of sulfide solid electrolyte.

[0071] Step 3: Mix heptane (non-polar main solvent), 3-mercaptopropyltrimethoxysilane (first stabilizer), and hexafluorobenzene (second stabilizer) in a volume ratio of 5:2:1, and stir magnetically for a certain period of time to form a homogeneous and transparent mixed solution.

[0072] Step 4: Place the 2g coarse sulfide solid electrolyte particles prepared in Step 2 and the mixed solution prepared in Step 3 into a ball mill jar at a mass ratio of 1:5. The mass ratio of the particles is 30:1, the diameter of the grinding beads is 1mm, and a planetary ball mill is used for grinding. The ball mill speed is 400rpm and the grinding time is 5h. After the operation is completed, a uniformly dispersed electrolyte slurry is obtained.

[0073] Step 5: Centrifuge the ball-milled electrolyte slurry at 10,000 rpm to separate the solids and liquids, and collect the solids.

[0074] Step 6: The separated solid material is vacuum dried at 100℃ for 12 hours to completely remove residual solvent;

[0075] Step 7: Under an inert atmosphere, heat-treat at 100°C for 2 hours to obtain a sulfide solid electrolyte with a refined particle size.

[0076] Example 2

[0077] Step 1: Weigh 6.9g of lithium sulfide, 8.3g of phosphorus pentasulfide and 4.8g of lithium chloride, and mix them by ball milling in an inert atmosphere. The ball-to-material ratio is 50:1, the ball diameter is 5mm, the ball milling speed is 500rpm, and the ball milling is carried out for 12h to obtain the precursor powder.

[0078] Step 2: Place the precursor powder into a sealed crucible, place it in a tube furnace, heat it to 500℃ at 2℃ / min and calcine for 8 hours. After cooling to room temperature, crush it three times with a crusher at a speed of 25000rpm / min for 20s each time to obtain coarse particles of sulfide solid electrolyte.

[0079] Step 3: Mix hexane (non-polar main solvent), 3-mercaptopropylmethyldimethoxysilane (first stabilizer), and 1,3,5-trifluorobenzene (second stabilizer) in a volume ratio of 5:2:1. After stirring magnetically for a certain period of time, a homogeneous and transparent mixed solution is formed.

[0080] Step 4: Place the 2g coarse sulfide solid electrolyte particles prepared in Step 2 and the mixed solution prepared in Step 3 into a ball mill jar at a mass ratio of 1:5, with a material-to-bead ratio of 20:1 and a ball mill bead diameter of 1mm. Use a planetary ball mill at a speed of 450rpm for 5h. After the operation is completed, a uniformly dispersed electrolyte slurry is obtained.

[0081] Step 5: Centrifuge the ball-milled electrolyte slurry at 10,000 rpm to separate the solids and liquids, and collect the solids.

[0082] Step 6: The separated solid material is vacuum dried at 60°C for 12 hours to completely remove residual solvent;

[0083] Step 7: Under an inert atmosphere, heat-treat at 100°C for 2 hours to obtain a sulfide solid electrolyte with a refined particle size.

[0084] Example 3

[0085] Step 1: Weigh 6.9g of lithium sulfide, 8.3g of phosphorus pentasulfide and 4.8g of lithium chloride, and mix them by ball milling in an inert atmosphere. The ball-to-material ratio is 50:1, the ball diameter is 5mm, the ball milling speed is 500rpm, and the ball milling is carried out for 12h to obtain the precursor powder.

[0086] Step 2: Place the precursor powder into a sealed crucible, place it in a tube furnace, heat it to 500℃ at 2℃ / min and calcine for 8 hours. After cooling to room temperature, crush it three times with a crusher at a speed of 25000rpm / min for 20s each time to obtain coarse particles of sulfide solid electrolyte.

[0087] Step 3: Mix heptane (non-polar main solvent), 3-mercaptopropyltriethoxysilane (first stabilizer), and hexafluorotrimethyltoluene (second stabilizer) in a volume ratio of 5:2:1. After stirring magnetically for a certain period of time, a homogeneous and transparent mixed solution is formed.

[0088] Step 4: Place the 2g coarse sulfide solid electrolyte particles prepared in Step 2 and the mixed solution prepared in Step 3 into a ball mill jar at a mass ratio of 1:5, with a material-to-bead ratio of 30:1 and a ball bead diameter of 1mm. Use a planetary ball mill at a speed of 500rpm for 3h. After the operation, a uniformly dispersed electrolyte slurry is obtained.

[0089] Step 5: Centrifuge the ball-milled electrolyte slurry at 10,000 rpm to separate the solids and liquids, and collect the solids.

[0090] Step 6: The separated solid material is vacuum dried at 100℃ for 6 hours to completely remove residual solvent;

[0091] Step 7: Under an inert atmosphere, heat-treat at 120°C for 3 hours to obtain a sulfide solid electrolyte with a refined particle size.

[0092] Example 4

[0093] Step 1: Weigh 6.9g of lithium sulfide, 8.3g of phosphorus pentasulfide and 4.8g of lithium chloride, and mix them by ball milling in an inert atmosphere. The ball-to-material ratio is 50:1, the ball diameter is 5mm, the ball milling speed is 500rpm, and the ball milling is carried out for 12h to obtain the precursor powder.

[0094] Step 2: Place the precursor powder into a sealed crucible, place it in a tube furnace, heat it to 500℃ at 2℃ / min and calcine for 8 hours. After cooling to room temperature, crush it three times with a crusher at a speed of 25000rpm / min for 20s each time to obtain coarse particles of sulfide solid electrolyte.

[0095] Step 3: Mix m-xylene (non-polar main solvent), bis-(3-triethoxysilylpropyl)-disulfide (first stabilizer), and perfluorobiphenyl (second stabilizer) in a volume ratio of 4:3:1. After stirring magnetically for a certain period of time, a homogeneous and transparent mixed solution is formed.

[0096] Step 4: Place the 2g coarse sulfide solid electrolyte particles prepared in Step 2 and the mixed solution prepared in Step 3 into a ball mill jar at a mass ratio of 1:5. The mass ratio of the particles is 20:1, the diameter of the grinding beads is 1mm, and a planetary ball mill is used for grinding. The ball mill speed is 400rpm and the grinding time is 6h. After the operation is completed, a uniformly dispersed electrolyte slurry is obtained.

[0097] Step 5: Centrifuge the ball-milled electrolyte slurry at 10,000 rpm to separate the solids and liquids, and collect the solids.

[0098] Step 6: The separated solid material is vacuum dried at 120℃ for 18 hours to completely remove residual solvent;

[0099] Step 7: Under an inert atmosphere, heat-treat at 220°C for 5 hours to obtain a sulfide solid electrolyte with a refined particle size.

[0100] Example 5

[0101] Step 1: Weigh 6.9g of lithium sulfide, 8.3g of phosphorus pentasulfide and 4.8g of lithium chloride, and mix them by ball milling in an inert atmosphere. The ball-to-material ratio is 50:1, the ball diameter is 5mm, the ball milling speed is 500rpm, and the ball milling is carried out for 12h to obtain the precursor powder.

[0102] Step 2: Place the precursor powder into a sealed crucible, place it in a tube furnace, heat it to 500℃ at 2℃ / min and calcine for 8 hours. After cooling to room temperature, crush it three times with a crusher at a speed of 25000rpm / min for 20s each time to obtain coarse particles of sulfide solid electrolyte.

[0103] Step 3: Mix heptane (non-polar main solvent), 3-mercaptopropyltrimethoxysilane (first stabilizer), and hexafluorobenzene (second stabilizer) in a volume ratio of 4:3:1, and stir magnetically for a certain period of time to form a homogeneous and transparent mixed solution.

[0104] Step 4: Place the 2g coarse sulfide solid electrolyte particles prepared in Step 2 and the mixed solution prepared in Step 3 into a ball mill jar at a mass ratio of 1:5. The mass ratio of the particles is 30:1, the diameter of the grinding beads is 1mm, and a planetary ball mill is used for grinding. The ball mill speed is 400rpm and the grinding time is 5h. After the operation is completed, a uniformly dispersed electrolyte slurry is obtained.

[0105] Step 5: Centrifuge the ball-milled electrolyte slurry at 10,000 rpm to separate the solids and liquids, and collect the solids.

[0106] Step 6: The separated solid material is vacuum dried at 100℃ for 12 hours to completely remove residual solvent;

[0107] Step 7: Under an inert atmosphere, heat-treat at 100°C for 6 hours to obtain a sulfide solid electrolyte with a refined particle size.

[0108] Example 6

[0109] Step 1: Weigh 6.9g of lithium sulfide, 8.3g of phosphorus pentasulfide and 4.8g of lithium chloride, and mix them by ball milling in an inert atmosphere. The ball-to-material ratio is 50:1, the ball diameter is 5mm, the ball milling speed is 500rpm, and the ball milling is carried out for 12h to obtain the precursor powder.

[0110] Step 2: Place the precursor powder into a sealed crucible, place it in a tube furnace, heat it to 500℃ at 2℃ / min and calcine for 8 hours. After cooling to room temperature, crush it three times with a crusher at a speed of 25000rpm / min for 20s each time to obtain coarse particles of sulfide solid electrolyte.

[0111] Step 3: Mix heptane (non-polar main solvent), 3-mercaptopropyltrimethoxysilane (first stabilizer), and hexafluorobenzene (second stabilizer) in a volume ratio of 1:1:1, and stir magnetically for a certain period of time to form a homogeneous and transparent mixed solution.

[0112] Step 4: Place the 2g coarse sulfide solid electrolyte particles prepared in Step 2 and the mixed solution prepared in Step 3 into a ball mill jar at a mass ratio of 1:5. The mass ratio of the particles is 30:1, the diameter of the grinding beads is 0.5mm, and a planetary ball mill is used for grinding. The ball mill speed is 600rpm and the grinding time is 5h. After the operation is completed, a uniformly dispersed electrolyte slurry is obtained.

[0113] Step 5: Centrifuge the ball-milled electrolyte slurry at 10,000 rpm to separate the solids and liquids, and collect the solids.

[0114] Step 6: The separated solid material is vacuum dried at 100℃ for 6 hours to completely remove residual solvent;

[0115] Step 7: Under an inert atmosphere, heat-treat at 100°C for 3 hours to obtain a sulfide solid electrolyte with a refined particle size.

[0116] Comparative Example 1

[0117] The difference between this comparative example and Example 1 is that step three is as follows: heptane (non-polar main solvent) and 3-mercaptopropyltrimethoxysilane (first stabilizer) are mixed in a volume ratio of 5:2 and magnetically stirred for a certain period of time to form a homogeneous and transparent mixed solution.

[0118] The remaining steps are the same as in Example 1.

[0119] Comparative Example 2

[0120] The difference between this comparative example and Example 1 is that step three is as follows: heptane (non-polar main solvent) and hexafluorobenzene (second stabilizer) are mixed in a volume ratio of 5:1 and magnetically stirred for a certain period of time to form a homogeneous and transparent mixed solution.

[0121] The remaining steps are the same as in Example 1.

[0122] Comparative Example 3

[0123] The difference between this comparative example and Example 1 is that step three involves taking heptane (a nonpolar main solvent) as the mixed solution used in subsequent steps.

[0124] The remaining steps are the same as in Example 1.

[0125] Comparative Example 4

[0126] The difference between this comparative example and Example 1 is that step three is: replacing the nonpolar solvent with the polar solvent ethanol;

[0127] The remaining steps are the same as in Example 1.

[0128] Comparative Example 5

[0129] The difference between this comparative example and Example 1 is that in step three, heptane (nonpolar main solvent), 3-mercaptopropyltrimethoxysilane (first stabilizer), and perfluorobihexafluorobenzene (second stabilizer) are mixed in a volume ratio of 15:10:1.

[0130] The remaining steps are the same as in Example 1.

[0131] The ionic conductivity and particle size of the sulfide solid electrolytes prepared in the above embodiments and comparative examples were tested, and the test results are shown in Table 1.

[0132] The ionic conductivity was tested as follows: 100 mg of the prepared sulfide solid electrolyte was weighed and placed in a 10 mm diameter stainless steel pressing mold. The electrolyte sheet was pressed under a pressure of 350 MPa, and then carbon-coated aluminum foil was added to both sides of the electrolyte sheet for encapsulation. The mold was removed, placed in a battery clamp, and pressed under a pressure of 50 MPa to obtain a sandwich-type all-solid-state battery. The impedance and ionic conductivity of the solid electrolyte were measured by AC impedance method. The particle size was measured using a laser particle size analyzer according to conventional methods.

[0133] Table 1

[0134] Impedance (Ω) Ionic conductivity (mS / cm) D50 (μm) Example 1 15.6 6.1 0.70 Example 2 17 5.6 0.97 Example 3 20.6 4.6 1.32 Example 4 18.5 5.2 1.08 Example 5 24.6 3.9 1.5 Example 6 21.8 4.4 1.13 Comparative Example 1 32 2.99 1.79 Comparative Example 2 54 1.77 2.71 Comparative Example 3 18.5 5.2 6.27 Comparative Example 4 700 0.1 0.88 Comparative Example 5 1300 0.07 3.46

[0135] Combined with Table 1 and Figure 2 , Figure 3 It can be seen that the sulfide solid electrolytes prepared in Examples 1 to 6 of this application have better overall performance. Not only is the ionic conductivity maintained at a high level and the impedance at a low level, but the D50 particle size is also controlled within 1.5 μm. In contrast, the performance of the products in Comparative Examples 1 to 5 shows different degrees of deterioration in terms of particle size and conductivity.

[0136] In this application, the stabilizer and the main solvent work synergistically to achieve particle size refinement during the wet milling process. If only a non-polar solvent is used, such as heptane in Comparative Example 3, the synergistic dispersing effect of the stabilizer is lacking, resulting in a still relatively large electrolyte particle size, making it difficult to achieve the submicron refinement target. While directly replacing the non-polar solvent with a polar solvent, such as ethanol instead of heptane in Comparative Example 4, can achieve submicron particle size through the dispersibility of the polar solvent, the polar solvent will damage the PS4 of the sulfide electrolyte. 3-The monolayer structure leads to electrolyte decomposition, ultimately resulting in a significant decrease in ionic conductivity. However, the embodiments of this application utilize a nonpolar primary solvent and a stabilizer in synergy, ensuring the presence of a certain amount of polar solvent in the wet milling system. This achieves sub-micron particle size refinement without compromising the intrinsic conductivity of the electrolyte.

[0137] Depend on Figure 1 and Figure 4 The comparison shows that the sulfide solid electrolyte prepared in Example 1 maintained high purity after being placed in air for 30 minutes; while the product of Comparative Example 1 showed a significant decrease in purity after being placed under the same conditions. This is because the first and second stabilizers in the examples jointly constructed a dense and stable protective layer on the surface of the electrolyte particles, effectively blocking water and oxygen erosion and greatly improving the air stability of the electrolyte.

[0138] As shown in Comparative Example 5, when the proportions of the first and second stabilizers are too high, on the one hand, it leads to excessive polymer cross-linking during heat treatment. The excessively thick cross-linked layer severely hinders lithium-ion transport, resulting in a sharp decrease in ionic conductivity. On the other hand, in the wet milling solvent system, the presence of excessive highly polar solvents easily damages the electrolyte PS4. 3- The structure of the unit cells leads to electrolyte decomposition, thereby affecting ionic conductivity. In addition, excessive cross-linking can also cause secondary agglomeration of the refined particles, resulting in larger particle sizes.

[0139] In summary, the preparation system of this application utilizes a nonpolar main solvent, a first stabilizer, and a second stabilizer in synergy to generate a dense and stable protective layer on the surface of the sulfide solid electrolyte with refined particle size. Furthermore, the strength and density of this protective layer are far superior to the modification effect of a single stabilizer. The final prepared sulfide solid electrolyte not only has small and uniform particle size distribution, but also fully retains its intrinsic ionic conductivity and exhibits significantly enhanced air stability against water and oxygen corrosion, thus meeting the comprehensive performance requirements of electrolytes for the industrialization of all-solid-state batteries.

[0140] Obviously, the embodiments described above are only some embodiments of this application, not all embodiments. The accompanying drawings show preferred embodiments of this application, but do not limit the patent scope of this application. This application can be implemented in many different forms; rather, these embodiments are provided to provide a more thorough and comprehensive understanding of the disclosure of this application. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing specific embodiments, or make equivalent substitutions for some of the technical features. Any equivalent structures made using the content of this application's specification and drawings, directly or indirectly applied to other related technical fields, are similarly within the scope of patent protection of this application.

Claims

1. A method for preparing a sulfide solid electrolyte with refined particle size, characterized in that, The preparation method includes: A mixed solution is prepared, the mixed solution comprising a nonpolar main solvent, a first stabilizer, and a second stabilizer; wherein the first stabilizer comprises a silane coupling agent containing a thiol group, and the second stabilizer comprises a nonpolar fluorobenzene derivative; The pre-prepared coarse particles of sulfide solid electrolyte are dispersed in the mixed solution and ball-milled to obtain a uniformly dispersed electrolyte slurry. The electrolyte slurry is subjected to solid-liquid separation to collect the solid substances; After drying the solid material, it is heat-treated under an inert atmosphere to obtain a sulfide solid electrolyte with a finer particle size.

2. The method for preparing a sulfide solid electrolyte with refined particle size as described in claim 1, characterized in that, Before the step of dispersing the pre-prepared coarse particles of sulfide solid electrolyte in the mixed solution and ball milling them to obtain a uniformly dispersed electrolyte slurry, the method further includes: The precursor raw materials are weighed according to the stoichiometric ratio and mixed evenly in an inert atmosphere to obtain precursor powder. The precursor raw materials include lithium sulfide and phosphorus pentasulfide. The precursor powder was calcined and then cooled to room temperature before being crushed to obtain coarse particles of the sulfide solid electrolyte.

3. The method for preparing a sulfide solid electrolyte with refined particle size as described in claim 1, characterized in that, The nonpolar primary solvent includes at least one of hexane, octane, heptane, o-xylene, m-xylene, and p-xylene.

4. The method for preparing a sulfide solid electrolyte with refined particle size as described in claim 1, characterized in that, The first stabilizer includes at least one of 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 3-mercaptopropylmethyldimethoxysilane, and bis-(3-triethoxysilylpropyl)-disulfide.

5. The method for preparing a sulfide solid electrolyte with refined particle size as described in claim 1, characterized in that, The second stabilizer includes at least one of hexafluorobenzene, perfluorotrimethylbenzene, 1,3,5-trifluorobenzene, and perfluorobiphenyl.

6. The method for preparing a sulfide solid electrolyte with refined particle size as described in claim 1, characterized in that, The nonpolar primary solvent has a volume ratio of the first stabilizer to the second stabilizer of (1-10):(1-5):

1.

7. The method for preparing a sulfide solid electrolyte with refined particle size as described in claim 1, characterized in that, The step of dispersing pre-prepared coarse particles of sulfide solid electrolyte in the mixed solution and ball milling them to obtain a uniformly dispersed electrolyte slurry includes: Weigh the coarse particles of the sulfide solid electrolyte and the mixed solution at a mass ratio of 1:(1~20), place them in a ball mill jar for ball milling, and mill at a speed of 200 rpm~600 rpm for 1 h~9 h to obtain a uniformly dispersed electrolyte slurry.

8. The method for preparing a sulfide solid electrolyte with refined particle size as described in claim 1, characterized in that, The step of drying the solid material and then heat-treating it under an inert atmosphere to obtain a sulfide solid electrolyte with a fine particle size includes: The solid material is dried at 60℃~120℃ for 6h~18h to obtain the dried product; The dried product is subjected to heat treatment under an inert atmosphere. The heat treatment temperature is 80℃~250℃ and the heat treatment duration is 1h~6h.

9. A sulfide solid electrolyte, characterized in that, It is prepared by the method for preparing sulfide solid electrolyte with fine particle size as described in any one of claims 1-8; Preferably, the median particle size D50 of the sulfide solid electrolyte is 0.5 μm to 1.5 μm.

10. A solid-state battery, characterized in that, This includes sulfide solid electrolytes prepared by the method for preparing sulfide solid electrolytes with refined particle size as described in any one of claims 1-8.

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