A method for producing a sulfide solid electrolyte

Abstract

This invention belongs to the field of solid-state battery material preparation technology, and particularly relates to a method for preparing a sulfide solid electrolyte, comprising at least the following steps: mixing the raw materials and molten medium required for the sulfide solid electrolyte under an inert atmosphere, and placing the mixture in a sealed ball mill jar; mechanically grinding and simultaneously heating the ball mill jar in a heated ball milling system to obtain a molten suspension of the sulfide solid electrolyte; further heating the molten suspension of the sulfide solid electrolyte under an inert atmosphere or vacuum, causing the molten medium to boil or sublimate and separate from the sulfide solid electrolyte; and cooling to room temperature to obtain the sulfide solid electrolyte. Compared with the prior art, this invention uses molten medium-assisted heating mechanical ball milling to prepare the sulfide solid electrolyte, which can obtain a stable, high-purity, low-carbon-residue sulfide solid electrolyte with an ionic conductivity of 10.7 mS / cm, a carbon residue of <0.01 wt%, and a processing time of <2 h.

Description

Technical Field

[0001] This invention belongs to the field of solid-state battery material preparation technology, and particularly relates to a method for preparing a sulfide solid electrolyte, applicable to Li6PS5Cl and Li7P3S. 11 Large-scale production of sulfide systems. Background Technology

[0002] With the continuous pursuit of high energy density and high safety in new energy batteries, solid-state batteries have become the most promising next-generation power batteries, and sulfide solid electrolytes have become the core materials of solid-state batteries due to their high ionic conductivity, good thermal stability and mechanical properties. Their conventional preparation methods include dry ball milling, wet process and solid-state sintering: (1) Dry ball milling is to put raw materials such as Li2S and P2S5 into a ball milling jar for a long time to achieve the mixing and reaction effect of raw materials and obtain sulfide solid electrolytes; (2) Wet process is divided into two routes: dissolution and dispersion: dissolution refers to using an organic solvent that can dissolve raw materials such as Li2S and P2S5 to dissolve the raw materials to form a uniform solution, and then removing the solvent by heat treatment to obtain sulfide solid electrolytes; dispersion refers to using one or more non-polar organic solvents that do not react with raw materials such as Li2S and P2S5 as a medium to ball mill and mix the raw materials, and then obtaining sulfide solid electrolytes by heat treatment; (3) Solid-state sintering refers to sintering the precursor powder after uniformly mixing raw materials such as Li2S and P2S5 at high temperature to obtain sulfide solid electrolytes.

[0003] Currently, the mixing process in the synthesis of sulfide solid electrolytes typically uses dry stirring, which often results in uneven mixing due to dead zones in the equipment or caking of softer materials at high temperatures. Wet processes, on the other hand, often involve the addition of conventional organic solvents, which can lead to carbon residue and affect the purity of the solid electrolyte. Sulfide solid electrolytes prepared by these conventional methods suffer from drawbacks such as low phase purity, low crystallinity, high carbon residue, or high energy consumption, making it difficult to simultaneously meet the technical requirements of solid-state batteries for sulfide solid electrolytes, such as high phase purity, low carbon residue, high ionic conductivity, and low electronic conductivity. Therefore, there is an urgent need to develop a uniform mixing process free of impurities, which is an innovative method to improve the quality stability of sulfide solid electrolytes and reduce costs.

[0004] In view of this, the present invention aims to provide a method for preparing a sulfide solid electrolyte, which obtains the sulfide solid electrolyte through molten medium-assisted ball milling, and is applicable to Li6PS5Cl and Li7P3S. 11 Large-scale production of sulfide systems. This avoids uneven mixing of raw materials and the introduction of impurities, effectively improving the purity and ionic conductivity of electrolytes, and enabling high-efficiency, low-cost mass production. Summary of the Invention

[0005] To address the shortcomings of existing technologies, a method for preparing sulfide solid electrolytes is provided. This method involves preparing sulfide solid electrolytes through molten medium-assisted ball milling, and is applicable to Li6PS5Cl and Li7P3S... 11 Large-scale production of sulfide systems. This avoids uneven mixing of raw materials and the introduction of impurities, effectively improving the purity and ionic conductivity of electrolytes, and enabling high-efficiency, low-cost mass production.

[0006] To solve the above problems, the technical solution of the present invention is as follows:

[0007] A method for preparing a sulfide solid electrolyte includes at least the following steps:

[0008] The first step is to mix the raw materials and molten medium required for the sulfide solid electrolyte under an inert atmosphere and place them in a sealed ball mill jar;

[0009] The second step involves mechanically grinding and simultaneously heating the ball mill jar from the first step in a heated ball milling system to obtain a sulfide solid electrolyte molten suspension.

[0010] The third step involves further heating the molten suspension of the sulfide solid electrolyte from the second step under an inert atmosphere or vacuum, causing the molten medium to boil, evaporate, or sublimate, separating it from the sulfide solid electrolyte. After cooling to room temperature, the sulfide solid electrolyte is obtained.

[0011] As an improvement to the preparation method of the sulfide solid electrolyte of the present invention, the raw materials required for the sulfide solid electrolyte in the first step include at least two of the following: lithium, sodium, sulfur, lithium sulfide, sodium sulfide, lithium selenide, lithium oxide, germanium sulfide, silicon sulfide, tin sulfide, phosphorus pentasulfide, phosphorus pentoxide, lithium chloride, sodium chloride, lithium bromide, sodium bromide, lithium iodide, sodium iodide, lithium fluoride, and sodium fluoride.

[0012] As an improvement to the preparation method of the sulfide solid electrolyte of the present invention, the initial particle size of the raw materials required for the sulfide solid electrolyte in the first step is 0.01-3 mm.

[0013] As an improvement to the preparation method of the sulfide solid electrolyte of the present invention, a doped metal is added in the first step. The doped metal includes at least one of Ge, Sn, Al, Ca, Mg, Fe, Zn, Zr, Ti, Ag, Cu, Se, Bi, Si, Mo, Hf, Ta, Nb, W, Sc, Mn, and Co.

[0014] As an improvement to the preparation method of the sulfide solid electrolyte of the present invention, the melting medium in the first step is elemental sulfur or sodium thiosulfate.

[0015] As an improvement to the preparation method of the sulfide solid electrolyte of the present invention, the amount of molten medium added is 50%-400% of the raw material mass percentage. In some optional embodiments, the amount of molten medium added can be 50%, 100%, 200% or 400% of the raw material mass percentage, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0016] As an improvement to the preparation method of the sulfide solid electrolyte of the present invention, in the first step, the material of the grinding jar is at least one of stainless steel, zirconium oxide, silicon carbide, tungsten carbide, agate, corundum, nylon, polytetrafluoroethylene, and polyurethane; the material of the grinding balls in the grinding jar is selected from at least one of stainless steel, zirconium oxide, silicon carbide, tungsten carbide, agate, corundum, nylon, polytetrafluoroethylene, and polyurethane.

[0017] As an improvement to the preparation method of the sulfide solid electrolyte of the present invention, the structure of the main body of the ball mill jar in the first step is a single layer, a double layer with an inner lining or a hollow sandwich structure, and the structure of the ball mill jar lid is one of a flat sealing element, a flat sealing element with a valve, a curved sealing element, or a curved sealing element with a valve. The locking element between the main body of the ball mill jar and the lid is a screw or a clamp.

[0018] As an improvement to the preparation method of the sulfide solid electrolyte of the present invention, in the second step, the ball milling system with heating is a planetary ball mill, a horizontal ball mill, a high-energy ball mill, a vibratory ball mill, a roller mill, a grinding mill, an air jet mill, or a high-speed mixer; the heating method is at least one of integrated resistance heating rod / tube / plate, induction heating, and fluid circulation heating.

[0019] As an improvement to the preparation method of the sulfide solid electrolyte of the present invention, in the second step, the pressure inside the ball mill jar is -0.1 to 0.2 MPa, the ball-to-material ratio is 5-20:1, the size of the grinding balls is 0.1-10 mm, the ball milling speed is 100-900 rpm, the heating temperature is 55-200℃, and the ball milling time is 1-20 h.

[0020] As an improvement to the preparation method of the sulfide solid electrolyte of the present invention, the heating method of the solid electrolyte molten suspension in the third step is to heat it in a heated ball mill jar under normal pressure or vacuum, and remove the molten medium in the solid electrolyte molten suspension by boiling evaporation or sublimation. The heating equipment used in this step can also be at least one of a heating table, vacuum oven, muffle furnace, tube furnace, and atmosphere lifting furnace.

[0021] This invention employs a dynamic dispersion technology using molten medium, with elemental sulfur (melting point 115℃) or sodium thiosulfate as the medium. Solid electrolyte raw materials are pulverized and mixed in a liquid state at 60-130℃, achieving in-situ refinement of large particles (1-3mm) with a D50 ≤ 1μm. This invention also utilizes a high-temperature synergistic ball milling system, employing a conventional ball mill jar with a heating jacket (temperature < 200℃), achieving an energy consumption of only 800kWh / ton, a 63.6% reduction compared to traditional processes. Furthermore, this invention leaves no impurities because the medium has a low boiling point, allowing for complete removal through boiling or sublimation. Moreover, the presence of sulfur in the medium also provides sulfur replenishment to the solid electrolyte, better preserving the chemical structure of the sulfide solid electrolyte.

[0022] Compared with the prior art, the beneficial effects of the technical solution of the present invention are as follows:

[0023] (1) The present invention uses mechanical ball milling with molten medium assisted heating to prepare sulfide solid electrolyte, which can obtain stable, high-purity, low carbon residue sulfide solid electrolyte with ionic conductivity of 10.7 mS / cm, carbon residue <0.01 wt%, and processing time <2 h.

[0024] (2) Compared with traditional dry ball milling, the dynamic dispersion technology of molten medium can reduce the initial particle size of raw materials and avoid caking of raw materials during ball milling, effectively improving the uniformity of raw material reaction. Compared with traditional wet ball milling, it can effectively avoid solvent residue. It can also replenish sulfur in solid electrolytes and improve the chemical structure stability. The solid electrolyte synthesized by the new technology has good stability and high ionic conductivity, thereby improving the electrochemical performance of solid batteries.

[0025] (3) The high-temperature synergistic ball milling system can reduce production time and energy consumption compared with traditional dry ball milling and solid-state sintering technology.

[0026] (4) The preparation technique of the present invention is applicable to Li6PS5Cl and Li7P3S 11 Large-scale production of sulfide systems. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the molten medium penetration and refining mechanism.

[0028] Figure 2 This is a schematic diagram of the components of a sealed heating ball mill system.

[0029] Figure 3 This is a schematic diagram of a sealed heating ball mill.

[0030] In the diagram: 1. Protective gas valve, 2. Grinding jar cover, 3. Flange clamp, 4. Sealing ring, 5. Ceramic liner of grinding jar, 6. Metal outer shell of grinding jar, 7. Heating jacket of grinding jar, 8. Insulation layer of grinding jar, 9. Drive shaft, 10. Temperature controller and connected temperature sensor, 11. Motor controller. Detailed Implementation

[0031] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions in the embodiments of this application will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0032] Unless otherwise specified, the experimental methods used in the embodiments of this application are all conventional methods.

[0033] In the following examples and comparative examples, unless otherwise specified, all raw materials can be prepared, synthesized, or commercially available by conventional methods.

[0034] Example 1

[0035] This embodiment provides a sulfide solid electrolyte Li7P3S. 11 The preparation method includes the following steps:

[0036] Under argon protection, industrial-grade Li₂S (1 mm) and P₂S₅ (2 mm) were mixed at a molar ratio of 7:3; 50 wt% sulfur powder was added, and the mixture was loaded into a heated ball mill jar; 10 mm grinding beads were added at a ball-to-material ratio of 5:1, and the mixture was loaded into the heated ball mill jar. The jar was sealed, and a vacuum was applied to obtain a pressure of -0.1 MPa inside the ball mill jar. Mechanical grinding and simultaneous heating were performed in a heated ball mill system, set at 120°C and heated for 10 min; under argon protection, the ball milling time was 1 h at a speed of 900 rpm to obtain Li₇P₃S. 11 A solid electrolyte molten suspension was then vacuum-dried at 150°C in a heated ball mill to obtain Li7P3S. 11 The solid electrolyte, after being cooled to room temperature (25°C), had an ionic conductivity of 7.3 mS / cm and a carbon content of 0.05%.

[0037] The grinding jar is made of stainless steel. The grinding balls inside the jar are made of zirconium oxide.

[0038] The main body of the grinding jar has a double-layered structure with an inner liner, and the lid is a flat sealing piece. The jar body and lid are secured with screws. In heated grinding systems, the grinding system is a planetary ball mill, and the heating method is an integrated resistance heating rod.

[0039] The schematic diagram of the molten medium penetration and refining mechanism in this embodiment is shown below. Figure 1 As shown, its penetration and refining mechanism is explained in detail below:

[0040] During the heated ball milling process, the raw materials are dynamically penetrated and refined by the molten medium (elemental sulfur S8). The mechanical force continuously breaks down the raw material particles, exposing fresh active surfaces. The molten medium immediately coats the particles and forces them into the microcracks and interfaces through capillary force and mechanical shear force, achieving physical separation. At the same time, the molten medium coating layer effectively inhibits the re-agglomeration of particles and grain growth, thereby achieving efficient, deep refinement and uniform mixing of the raw materials, resulting in a high-performance and stable sulfide solid electrolyte.

[0041] The sealed heating ball mill system used in this invention is as follows: Figure 2 As shown, it includes a power supply and control system (including an external power supply, a temperature controller, and a motor controller), a heating and insulation system (including a heating jacket, an insulation layer, and a temperature sensor), a drive structure (drive motor, transmission shaft, and support base), and a sealed tank system (including a tank body, a tank cover, a sealing ring, and a protective gas valve). The power supply and control system supplies power to the heating and insulation system and controls the temperature. The power supply and control system also supplies power to the drive structure and controls its rotation speed. The heating and insulation system provides heating for the sealed tank system, and the drive structure drives the sealed tank system to rotate.

[0042] A schematic diagram of a sealed heating ball mill is shown below. Figure 3 As shown, it includes, from the inside out, a ceramic liner 5, a metal shell 6, a heating jacket 7, and a heat insulation layer 8 of a grinding jar. A grinding jar lid 2 is provided at the opening of the ceramic liner 5, and a sealing ring 4 is provided between the two. A protective gas valve 1 is provided on the grinding jar lid 2. A drive shaft 9 is provided at the bottom of the heat insulation layer 8 of the grinding jar. A motor controller 11 is connected to the drive shaft 9. A temperature controller and a temperature sensor 10 are connected to the heating jacket 7 of the grinding jar.

[0043] Example 2

[0044] This embodiment provides a sulfide solid electrolyte Li 5.5 PS 4.5 Cl 1.5 The preparation method includes the following steps:

[0045] Industrial-grade Li₂S (0.5 mm), P₂S₅ (2 mm), and LiCl (0.5 mm) were mixed in a 4:1:3 molar ratio under argon protection. 100 wt% sulfur powder was added, and the mixture was loaded into a heated ball mill jar. 10 mm grinding beads were added at a ball-to-material ratio of 5:1, and the jar was sealed. The initial pressure inside the ball mill jar was 0 MPa. Mechanical grinding and simultaneous heating were performed in a heated ball mill system, set at 140°C for 10 min. The ball milling time under argon protection was 10 h at a speed of 500 rpm to obtain LiCl. 5.5 PS 4.5 Cl 1.5 A solid electrolyte molten suspension was then vacuum-dried in a tube furnace at 400°C to obtain Li. 5.5 PS 4.5 Cl 1.5 The solid electrolyte, after being cooled to room temperature (25°C), had an ionic conductivity of 10.8 mS / cm and a carbon content of 0.04%.

[0046] Unlike Example 1, the grinding jar is made of silicon carbide. The main body of the grinding jar has a single-layer structure, and the lid is a flat plate with a valve. In the heated grinding system, the grinding system is a horizontal grinding mill, and the heating method is an integrated resistance heating tube.

[0047] Example 3

[0048] This embodiment provides a sulfide solid electrolyte Li 10 GeP2S 12 The preparation method includes the following steps:

[0049] Industrial-grade Li₂S (0.2 mm), P₂S₅ (1 mm), and GeS₂ (0.5 mm) were mixed in a molar ratio of 5:1:1. 200 wt% sulfur powder was added, and the mixture was placed in a heated ball mill jar. 5 mm grinding beads were added at a ball-to-material ratio of 10:1, and the jar was sealed. A vacuum was applied to obtain a pressure of -0.1 MPa inside the ball mill jar. Mechanical grinding and simultaneous heating were performed in a heated ball mill system, set to 200°C and heated for 10 minutes. The ball milling time was 20 hours under argon protection at a speed of 300 rpm to obtain Li₂S (0.2 mm). 10 GeP2S 12 A solid electrolyte molten suspension was then vacuum-dried in a tube furnace at 400°C to obtain Li. 10 GeP2S 12 The solid electrolyte, after being cooled to room temperature (25°C), had an ionic conductivity of 14.2 mS / cm and a carbon content of 0.03%.

[0050] Unlike Example 1, the grinding jar is made of tungsten carbide, and the grinding balls inside are made of silicon carbide. The main body of the grinding jar has a hollow sandwich structure, and the lid is a curved panel seal. In the heated grinding system, the grinding system is a high-speed mixer; the heating method is induction heating.

[0051] Example 4

[0052] This embodiment provides a sulfide solid electrolyte Li 10 SnP2S 12 The preparation method includes the following steps:

[0053] Industrial-grade Li₂S (0.05 mm), P₂S₅ (1 mm), and SnS₂ (0.5 mm) were mixed in a molar ratio of 5:1:1. 400 wt% Na₂S₂O₃ was added, and the mixture was placed in a heated ball mill jar. 0.1 mm grinding beads were added at a ball-to-material ratio of 20:1, and the jar was filled with the mixture. The jar was sealed, and a vacuum was applied to obtain a pressure of -0.1 MPa inside the mill jar. Mechanical grinding and simultaneous heating were performed in a heated ball mill system, set to 60°C and heated for 10 minutes. The milling time was 10 hours under argon protection at a speed of 300 rpm to obtain Li₂S. 10 SnP2S 12 A solid electrolyte molten suspension was then vacuum-dried at 100°C in a heated ball mill to obtain Li. 10 SnP2S 12 The solid electrolyte, after being cooled to room temperature (25°C), had an ionic conductivity of 6.5 mS / cm and a carbon content of 0.03%.

[0054] Unlike Example 1, the grinding jar is made of corundum; the grinding balls inside the jar are made of polytetrafluoroethylene (PTFE). The jar lid has a curved panel with a valve, and the jar body and lid are locked together by clamps. In the heated grinding system, the grinding system uses a vibrating grinding mill; the heating method is fluid circulation heating.

[0055] Example 5

[0056] This embodiment provides a sulfide solid electrolyte Li 5.4 PS 4.4 Cl 1.6 The preparation method includes the following steps:

[0057] Industrial-grade Li₂S (1 mm), P₂S₅ (0.5 mm), and LiCl (0.5 mm) were mixed in a molar ratio of 3.4:1:3.2. 100 wt% sulfur powder was added, and the mixture was loaded into a heated ball mill jar. 10 mm grinding beads were added at a ball-to-material ratio of 5:1, and the jar was sealed. Argon gas was then introduced to achieve a pressure of 0.2 MPa inside the jar. Mechanical grinding and simultaneous heating were performed in a heated ball mill system at 140°C for 10 minutes. The milling time was 15 hours under argon protection at a speed of 500 rpm to obtain LiCl. 5.4 PS 4.4 Cl 1.6 A solid electrolyte molten suspension was then vacuum-dried at 150°C in a vacuum oven to obtain Li. 5.4 PS 4.4 Cl 1.6 The solid electrolyte, after being cooled to room temperature (25°C), had an ionic conductivity of 12.6 mS / cm and a carbon content of 0.02%.

[0058] Unlike Example 1, the grinding jar is made of tungsten carbide; the grinding balls inside the jar are made of corundum. The main structure of the grinding jar is a hollow sandwich structure. In the heated grinding system, the grinding system is a roller mill; the heating method is an integrated resistance heating element.

[0059] Example 6

[0060] This embodiment provides a sulfide solid electrolyte Li 5.5 PS 4.5 Cl 1.5 The preparation method includes the following steps:

[0061] Industrial-grade Li₂S (0.5 mm), P₂S₅ (0.5 mm), and LiCl (0.3 mm) were mixed in a molar ratio of 4:1:3. 100 wt% Na₂S₂O₃ was added, and the mixture was placed in a heated ball mill jar. 5 mm grinding beads were added at a ball-to-material ratio of 10:1, and the jar was sealed. Argon gas was then introduced to achieve a pressure of 0.1 MPa inside the jar. Mechanical grinding and simultaneous heating were performed in a heated ball mill system, set at 70°C for 10 minutes. The milling time was 20 hours under argon protection at a speed of 100 rpm to obtain Li₂S (0.5 mm). 5.5 PS 4.5 Cl 1.5 A solid electrolyte molten suspension was then vacuum-dried at 120°C in a vacuum oven to obtain Li. 5.5 PS 4.5 Cl 1.5 The solid electrolyte had a tested ionic conductivity of 8.1 mS / cm and a carbon content of 0.05%.

[0062] Unlike Example 1, the grinding jar is made of zirconium oxide; the grinding balls inside the jar are made of stainless steel. The main body of the grinding jar has a hollow sandwich structure, and the lid is a flat plate with a valve. The locking mechanism between the main body and the lid is a clamp. In the heated grinding system, the grinding system is an air jet mill; the heating method is an integrated resistance heating element.

[0063] Example 7

[0064] This embodiment provides a sulfide solid electrolyte Li 5.5 PS 4.5 Cl 1.5 The preparation method includes the following steps:

[0065] Industrial-grade Li₂S (0.2 mm), P₂S₅ (0.2 mm), and LiCl (0.2 mm) were mixed in a molar ratio of 4:1:3. 100 wt% sulfur powder was added, and the mixture was loaded into a heated ball mill jar. 5 mm grinding beads were added at a ball-to-material ratio of 10:1, and the jar was sealed. The initial pressure inside the ball mill jar was 0 MPa. Mechanical grinding and simultaneous heating were performed in a heated ball mill system, set to 200°C and heated for 10 min. The ball milling time was 1 h under argon protection at a speed of 900 rpm to obtain Li. 5.5 PS 4.5 Cl 1.5 A solid electrolyte molten suspension was then vacuum-dried at 150°C in a heated ball mill to obtain Li. 5.5 PS 4.5 Cl 1.5 The solid electrolyte, after being cooled to room temperature (25°C), had an ionic conductivity of 9.3 mS / cm and a carbon content of 0.04%.

[0066] Unlike Example 1, the grinding jar is made of agate; the grinding balls inside the jar are made of polytetrafluoroethylene (PTFE). The jar lid has a curved panel seal, and the jar body and lid are locked together using clamps. In the heated grinding system, the grinding system is a high-energy ball mill; the heating method is induction heating.

[0067] Example 8

[0068] This embodiment provides a sulfide solid electrolyte Li 5.5 PS 4.5 Cl 1.5 The preparation method includes the following steps:

[0069] Industrial-grade Li₂S (0.05 mm), P₂S₅ (0.1 mm), and LiCl (0.2 mm) were mixed in a molar ratio of 4:1:3. 200 wt% Na₂S₂O₃ was added, and the mixture was loaded into a heated ball mill jar. 5 mm grinding beads were added at a ball-to-material ratio of 10:1, and the jar was sealed. The initial pressure inside the ball mill jar was 0 MPa. Mechanical grinding and simultaneous heating were performed in a heated ball mill system, set to 80°C and heated for 10 min. The ball milling time was 10 h under argon protection at a speed of 500 rpm. Li₂S (0.05 mm), P₂S₅ (0.1 mm), and LiCl (0.2 mm) were obtained. 5.5 PS 4.5 Cl 1.5 A solid electrolyte molten suspension was then dried at 140°C under inert gas protection to obtain Li. 5.5 PS 4.5 Cl 1.5 The solid electrolyte had a tested ionic conductivity of 7.5 mS / cm and a carbon content of 0.05%.

[0070] Unlike Example 1, the grinding jar is made of nylon. The main body of the grinding jar has a hollow sandwich structure, and the lid has a curved panel with a valve. The locking mechanism between the main body and the lid is a clamp. In the heated grinding system, the grinding system is a grinder; the heating method is fluid circulation heating.

[0071] Example 9

[0072] This embodiment provides a sulfide solid electrolyte Li 5.5 PS 4.5 Br 1.5 The preparation method includes the following steps:

[0073] Industrial-grade Li₂S (0.01 mm), P₂S₅ (0.05 mm), and LiBr (0.05 mm) were mixed in a molar ratio of 4:1:3. 200 wt% sulfur powder was added, and the mixture was loaded into a heated ball mill jar. 0.1 mm grinding beads were added at a ball-to-material ratio of 20:1, and the mixture was loaded into the heated ball mill jar. The jar was sealed, and a vacuum was applied to obtain a pressure of -0.1 MPa inside the jar. Mechanical grinding and simultaneous heating were performed in a heated ball mill system, set to 100°C and heated for 10 minutes. The ball milling time was 20 hours under argon protection at a speed of 400 rpm to obtain Li. 5.5 PS 4.5 Br 1.5 A solid electrolyte molten suspension was then dried in a box furnace at 400°C under inert gas protection to obtain Li. 5.5 PS 4.5 Br 1.5 The solid electrolyte had a tested ionic conductivity of 7.0 mS / cm and a carbon content of 0.04%.

[0074] Unlike Example 1, the grinding jar is made of nylon; the grinding balls inside the jar are made of polyurethane. The jar lid has a curved panel seal, and the jar body and lid are locked together using clamps. In the heated grinding system, the grinding system is a horizontal ball mill, and the heating method is an integrated resistance heating element.

[0075] Example 10

[0076] This embodiment provides a sulfide solid electrolyte Li 3.3 Zn 0.1 P 0.9 The preparation method of S4 includes the following steps:

[0077] Industrial-grade Li₂S (0.01 mm), P₂S₅ (3 mm), and ZnS (0.01 mm) were mixed in a molar ratio of 3.3:0.45:0.1. 300 wt% Na₂S₂O₃ was added, and the mixture was placed in a heated ball mill jar. 0.1 mm grinding beads were added at a ball-to-material ratio of 20:1, and the jar was sealed. The initial pressure inside the ball mill jar was 0 MPa. Mechanical grinding and simultaneous heating were performed in a heated ball mill system, set at 55°C for 10 min. The milling time was 15 h under argon protection at a rotation speed of 100 rpm to obtain Li₂S. 3.3 Zn 0.1 P 0.9 S4 solid electrolyte melt suspension; then vacuum dried in a heated ball mill at 120°C to obtain Li 3.3 Zn 0.1 P 0.9 The S4 solid electrolyte, after being cooled to room temperature (25°C), had an ionic conductivity of 0.73 mS / cm and a carbon content of 0.03%.

[0078] Unlike Example 1, the grinding jar is made of zirconium oxide; the grinding balls inside the jar are made of stainless steel. The main body of the grinding jar has a single-layer structure, and the locking device between the main body and the lid is a clamp.

[0079] In a heated ball mill system, the heating method is fluid circulation heating.

[0080] Comparative Example 1

[0081] This embodiment provides a sulfide solid electrolyte Li 5.5 PS 4.5 Cl 1.5 The preparation method includes the following steps:

[0082] 1. Mix industrial-grade Li₂S (1mm), P₂S₅ (2mm), and LiCl (1mm) in a molar ratio of 4:1:3;

[0083] 2. Add 200wt% n-heptane and load it into a heated ball mill jar;

[0084] 3. Add 5mm zirconia grinding balls at a ball-to-material ratio of 5:1, load into a heated grinding jar, seal the lid, and set to 25℃ room temperature without heating;

[0085] 4. The ball milling time under argon protection is 10 hours, and the rotation speed is 600 rpm;

[0086] 5. After vacuum drying at 100℃, Li was obtained. 5.5 PS 4.5 Cl 1.5 Solid electrolyte;

[0087] 6. The tested ionic conductivity was 6.8 mS / cm, and the carbon content was found to be 0.15%.

[0088] Comparative Example 2

[0089] This embodiment provides a sulfide solid electrolyte Li 5.5 PS 4.5 Cl 1.5 The preparation method includes the following steps:

[0090] 1. Mix industrial-grade Li2S (0.5mm), P2S5 (1mm), and LiCl (0.5mm) in a molar ratio of 4:1:3 and load the mixture into a heated ball mill jar;

[0091] 2. Add 5mm zirconia grinding balls at a ball-to-material ratio of 5:1, load into a heated grinding jar, seal the lid, and set to 25℃ room temperature (non-heated).

[0092] 4. The ball milling time under argon protection is 10 hours, and the speed is 500 rpm;

[0093] 5. After vacuum drying at 100℃, Li was obtained. 5.5 PS 4.5 Cl 1.5 Solid electrolyte;

[0094] 6. The tested ionic conductivity was 7.9 mS / cm, and the carbon content was measured to be 0.06%.

[0095] Comparative Example 3

[0096] This embodiment provides a sulfide solid electrolyte Li 5.5 PS 4.5 Cl 1.5 The preparation method includes the following steps:

[0097] 1. Mix industrial-grade Li₂S (1mm), P₂S₅ (2mm), and LiCl (1mm) in a molar ratio of 4:1:3;

[0098] 2. Add 200wt% anisole and load it into a heated ball mill jar;

[0099] 3. Add 5mm zirconia grinding balls at a ball-to-material ratio of 5:1, load into a heated grinding jar, seal the lid, and set to 25℃ room temperature without heating;

[0100] 4. The ball milling time under argon protection is 10 hours, and the rotation speed is 600 rpm;

[0101] 5. After vacuum drying at 100℃, Li was obtained. 5.5 PS 4.5 Cl 1.5 Solid electrolyte;

[0102] 6. The tested ionic conductivity was 6.3 mS / cm, and the carbon content was measured to be 0.22%.

[0103] Based on the disclosure and teachings of the foregoing specification, those skilled in the art can make changes and modifications to the above embodiments. Therefore, the present invention is not limited to the specific embodiments disclosed and described above, and some modifications and changes to the present invention should also fall within the protection scope of the claims of the present invention. Furthermore, although some specific terms are used in this specification, these terms are only for convenience of explanation and do not constitute any limitation on the present invention.

Claims

1. A method for preparing a sulfide solid electrolyte, characterized in that, It should include at least the following steps: The first step is to mix the raw materials and molten medium required for the sulfide solid electrolyte under an inert atmosphere and place them in a sealed ball mill jar; The second step involves mechanically grinding and simultaneously heating the ball mill jar from the first step in a heated ball milling system to obtain a sulfide solid electrolyte molten suspension. The third step involves further heating the molten suspension of the sulfide solid electrolyte from the second step under an inert atmosphere or vacuum, causing the molten medium to boil, evaporate, or sublimate, separating it from the sulfide solid electrolyte, and then cooling it to room temperature to obtain the sulfide solid electrolyte. In the second step, the pressure inside the ball mill jar is -0.1~0.2 MPa, the ball-to-material ratio is 5-20:1, the size of the grinding balls is 0.1-10 mm, the ball milling speed is 100~900 rpm, the heating temperature is 50~200℃, and the ball milling time is 1~20 h. In the first step, the melting medium is elemental sulfur or sodium thiosulfate; By dynamically penetrating and refining the raw materials through the molten medium during the heated ball milling process, the raw material particles are continuously broken down by mechanical force to expose fresh active surfaces. The molten medium immediately coats the particles and forces them into the microcracks and interfaces through capillary force and mechanical shear force, achieving physical separation. At the same time, the molten medium coating layer effectively inhibits the re-agglomeration of particles and grain growth, thereby achieving efficient, deep refining and uniform mixing of the raw materials, resulting in a high-performance and stable sulfide solid electrolyte.

2. The method for preparing the sulfide solid electrolyte according to claim 1, characterized in that, The raw materials required for the sulfide solid electrolyte in the first step include at least two of the following: lithium sulfide, sodium sulfide, lithium selenide, lithium oxide, germanium sulfide, silicon sulfide, tin sulfide, phosphorus pentasulfide, phosphorus pentoxide, lithium chloride, sodium chloride, lithium bromide, sodium bromide, lithium iodide, sodium iodide, lithium fluoride, and sodium fluoride.

3. The method for preparing the sulfide solid electrolyte according to claim 1, characterized in that, The initial particle size of the raw materials required for the sulfide solid electrolyte in the first step is 0.01-3 mm.

4. The method for preparing the sulfide solid electrolyte according to claim 1, characterized in that, The first step also involves adding a doped metal, which includes at least one of Ge, Sn, Al, Ca, Mg, Fe, Zn, Zr, Ti, Ag, Cu, Se, Bi, Si, Mo, Hf, Ta, Nb, W, Sc, Mn, and Co.

5. The method for preparing the sulfide solid electrolyte according to claim 1, characterized in that, The amount of the molten medium added is 50%-400% of the raw material mass percentage.

6. The method for preparing the sulfide solid electrolyte according to claim 1, characterized in that, In the first step, the grinding jar is made of at least one of the following materials: stainless steel, zirconium oxide, silicon carbide, tungsten carbide, agate, corundum, nylon, polytetrafluoroethylene, and polyurethane; the grinding balls inside the grinding jar are made of at least one of the following materials: stainless steel, zirconium oxide, silicon carbide, tungsten carbide, agate, corundum, nylon, polytetrafluoroethylene, and polyurethane.

7. The method for preparing the sulfide solid electrolyte according to claim 1, characterized in that, The first step is to determine the structure of the main body of the grinding jar, which can be single-layered, double-layered with an inner lining, or hollow sandwiched. The structure of the grinding jar lid can be one of the following: flat sealing element, flat sealing element with valve, curved sealing element, or curved sealing element with valve. The locking element between the main body of the grinding jar and the lid is a screw or a clamp.

8. The method for preparing the sulfide solid electrolyte according to claim 1, characterized in that, In the second step, the ball milling system with heating is a planetary ball mill, a horizontal ball mill, a high-energy ball mill, a vibratory ball mill, a roller mill, a grinding mill, an air jet mill, or a high-speed mixer; the heating method is at least one of integrated resistance heating rods / tubes / plates, induction heating, and fluid circulation heating.

9. The method for preparing a sulfide solid electrolyte according to claim 1, characterized in that, In the third step, the solid electrolyte molten suspension is heated in a heated ball mill jar under normal pressure or vacuum. The molten medium in the solid electrolyte molten suspension is removed by boiling evaporation or sublimation. The heating equipment used in this step can be replaced by at least one of the following: heating table, vacuum oven, muffle furnace, tube furnace, and atmosphere lifting furnace.

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