A sulfide solid electrolyte and preparation method thereof

Abstract

The present invention provides a sulfide solid electrolyte and a preparation method thereof, the preparation method comprising the following steps: subjecting raw materials Li2S, P2S5, LiX and a solvent to segmented ball milling under an inert atmosphere, followed by drying and sintering in sequence to obtain a sulfide solid electrolyte; wherein the segmented ball milling comprises at least two segments of ball milling. The present invention adopts a wet method to prepare a sulfide solid electrolyte, avoiding the operation of intermittent wall scraping and dispersing raw materials during the reaction. The preparation method is simple, the degree of manual intervention is low, the solvent can be recycled and reused multiple times, and environmental pollution is reduced. In addition, by adopting a segmented wet ball milling method, a sulfide solid electrolyte with high ionic conductivity can be obtained.

Description

Technical Field

[0001] The invention belongs to the technical field of solid-state batteries and relates to a sulfide solid electrolyte and a preparation method thereof. Background Art

[0002] All-solid-state batteries (ASSBs) using solid electrolytes are considered a promising next-generation energy storage technology that can achieve high theoretical energy density. Over the years, many sulfide-based solid electrolytes have been developed with significant progress, but despite great progress in achieving high ionic conductivity, it is still difficult to industrialize and mass-produce these solid electrolytes.

[0003] At present, the preparation method of sulfide solid electrolyte is to add Li2S, P2S5 and LiX (X = Cl, Br, I) as raw materials into a ball mill, and then sinter after several hours of ball milling reaction. Due to the large surface tension of sulfide, it is easy to adhere to the tank during the ball milling process to hinder the reaction, so the tank needs to be opened intermittently to disperse the raw materials again. Intermittent operation will lead to the introduction of impurities, affecting the performance of the final product, and this method requires a lot of manpower, making it difficult to achieve mass production of solid electrolytes.

[0004] In addition to the traditional solid-phase method for preparing sulfide solid electrolytes, the prior art also includes wet methods for preparing sulfide solid electrolytes, such as wet ball milling by adding solvents. However, conventional ball milling often has problems such as complicated reaction steps, expensive equipment, and low ionic conductivity. Summary of the invention

[0005] In view of the problems existing in the prior art, the present invention adopts a wet method to prepare a sulfide solid electrolyte, avoiding the operation of intermittent scraping and dispersing raw materials during the reaction. The preparation method is simple, the degree of human intervention is low, the solvent can be recycled and reused multiple times, and environmental pollution is reduced. In addition, by adopting a segmented wet ball milling method, the problems of uneven mixing of raw materials, insufficient material reaction, excessive by-products, cumbersome reaction steps, and low ionic conductivity existing in conventional wet ball milling are overcome, and the proportion of crystalline products can be increased to obtain a sulfide solid electrolyte with high ionic conductivity.

[0006] To achieve this object, the present invention adopts the following technical solutions:

[0007] In a first aspect, the present invention provides a method for preparing a sulfide solid electrolyte, the preparation method comprising the following steps:

[0008] The raw materials Li2S, P2S5, LiX and solvent are ball-milled in sections under an inert atmosphere, and then dried and sintered in sequence to obtain a sulfide solid electrolyte;

[0009] Wherein, the segmented ball milling includes at least two segments of ball milling.

[0010] As a preferred embodiment of the present invention, before the raw materials Li2S, P2S5, LiX and solvent are subjected to staged ball milling under an inert atmosphere, the process further comprises:

[0011] Pre-ball milling any one or at least two of Li2S, P2S5 or LiX;

[0012] The ball-to-material mass ratio of the pre-ball milling is (5-10):1, the ball milling time is 1h-10h, and the ball milling speed is 300rpm-900rpm.

[0013] As a preferred embodiment of the present invention, X in the raw material LiX is any one of I, Br or Cl.

[0014] As a preferred embodiment of the present invention, the stoichiometric ratio of the raw materials Li2S, P2S5 and LiX is based on the desired product Li 7-x PS 6-x Cl x Calculation shows that 0.5≤x≤2.

[0015] As a preferred embodiment of the present invention, the solvent includes any one of xylene, toluene, n-heptane or anisole, or a combination of at least two thereof.

[0016] As a preferred embodiment of the present invention, the ratio of the amount of the solvent to the total mass of the raw materials Li2S, P2S5 and LiX is (1-10):1.

[0017] As a preferred embodiment of the present invention, the inert atmosphere includes any one of argon atmosphere, helium atmosphere or neon atmosphere, or a combination of at least two of them.

[0018] As a preferred embodiment of the present invention, the preparation method comprises: premixing the raw materials Li2S, P2S5, LiX and a solvent and then performing segmented ball milling under an inert atmosphere.

[0019] As a preferred embodiment of the present invention, the premixing method includes magnetic stirring.

[0020] As a preferred embodiment of the present invention, the stirring rate of the magnetic stirring is 200 rpm-550 rpm, and the stirring time is 8 h-15 h.

[0021] As a preferred embodiment of the present invention, the rotation speed of each ball mill in the segmented ball milling gradually increases with an increase of 100rpm-300rpm.

[0022] As a preferred embodiment of the present invention, the mass ratio of ball to material in the segmented ball milling is (4-20):1.

[0023] As a preferred embodiment of the present invention, the segmented ball milling includes a first segment ball milling and a second segment ball milling.

[0024] As a preferred embodiment of the present invention, the rotation speed of the first stage ball milling is 200 rpm-300 rpm, and the ball milling time is 3 h-8 h.

[0025] As a preferred embodiment of the present invention, the first stage of ball milling includes three processes of forward rotation, intermittent rotation and reverse rotation, wherein the forward rotation time is 20min-60min, the intermittent time is 5min-20min, the reverse rotation time is 20min-60min, and the forward rotation, intermittent rotation and reverse rotation processes are cyclically performed, and the total cumulative time is 3h-8h.

[0026] As a preferred embodiment of the present invention, the rotation speed of the second stage ball milling is 400 rpm-600 rpm, and the ball milling time is 10 h-27 h.

[0027] As a preferred embodiment of the present invention, the second stage ball milling includes three processes: forward rotation, intermittent rotation and reverse rotation, wherein the forward rotation time is 20min-60min, the intermittent time is 5min-20min, the reverse rotation time is 20min-60min, and the forward rotation, intermittent rotation and reverse rotation processes are cyclically performed, and the total cumulative time is 10h-27h.

[0028] As a preferred embodiment of the present invention, the drying is carried out under an inert atmosphere, the drying temperature is less than 150° C., and the drying is carried out until the residual solvent content is less than 200 ppm.

[0029] As a preferred embodiment of the present invention, the inert atmosphere includes any one of argon atmosphere, helium atmosphere or neon atmosphere, or a combination of at least two of them.

[0030] As a preferred embodiment of the present invention, the sintering is carried out in an inert atmosphere, the sintering temperature is 400° C.-550° C., and the sintering time is 10 h-20 h.

[0031] As a preferred embodiment of the present invention, the inert atmosphere includes any one of argon atmosphere, helium atmosphere or neon atmosphere, or a combination of at least two of them.

[0032] In a second aspect, the present invention provides a sulfide solid electrolyte, which is prepared by the aforementioned preparation method.

[0033] Compared with the prior art, the present invention has the following beneficial effects:

[0034] (1) The present invention adopts segmented ball milling, especially speed-increasing ball milling, compared with ordinary uniform-speed ball milling and speed-reducing ball milling. The slow ball milling in the early stage can make the product mixing more uniform, and the fast ball milling in the later stage promotes the rapid reaction, improves the ball milling energy utilization rate, and then increases the proportion of crystalline products, so as to obtain a sulfide solid electrolyte with high ionic conductivity.

[0035] (2) The method of the present invention is simple to prepare, has a low degree of human intervention, and the solvent can be reused multiple times, thereby reducing environmental pollution. DETAILED DESCRIPTION

[0036] In order to better illustrate the present invention and facilitate understanding of the technical solution of the present invention, the present invention is further described in detail below. However, the following embodiments are only simple examples of the present invention and do not represent or limit the scope of protection of the present invention. The scope of protection of the present invention shall be subject to the claims.

[0037] In a first aspect, the specific implementation mode of the present invention provides a method for preparing a sulfide solid electrolyte, the preparation method comprising the following steps:

[0038] The raw materials Li2S, P2S5, LiX and solvent are ball-milled in sections under an inert atmosphere, and then dried and sintered in sequence to obtain a sulfide solid electrolyte;

[0039] Wherein, the segmented ball milling includes at least two segments of ball milling.

[0040] As a preferred embodiment of the present invention, before the raw materials Li2S, P2S5, LiX and solvent are subjected to staged ball milling under an inert atmosphere, the process further comprises:

[0041] Pre-ball milling any one or at least two of Li2S, P2S5 or LiX;

[0042] Among them, the mass ratio of ball to material in pre-ball milling is (5-10):1, for example 5:1, 6:1, 7:1, 8:1, 9:1 or 10:1, etc., but it is not limited to the listed values, and other values ​​not listed in the numerical range are also applicable; the ball milling time is 1h-10h, for example 1h, 2h, 4h, 6h, 8h or 10h, etc., but it is not limited to the listed values, and other values ​​not listed in the numerical range are also applicable; the ball milling speed is 300rpm-900rpm, for example 300rpm, 400rpm, 500rpm, 600rpm, 700rpm, 800rpm or 900rpm, etc., but it is not limited to the listed values, and other values ​​not listed in the numerical range are also applicable.

[0043] More specifically, the preparation method of the sulfide solid electrolyte includes:

[0044] Any one or at least two of Li2S, P2S5 or LiX are pre-milled, and the pre-milled materials and solvent are segmented-milled under an inert atmosphere, and then dried and sintered to obtain a sulfide solid electrolyte.

[0045] In the present invention, by pre-ball milling any one or at least two of Li2S, P2S5 or LiX, the particle size of the raw materials can be reduced, thereby reducing the subsequent ball milling reaction time.

[0046] As a preferred embodiment of the present invention, X in the raw material LiX is any one of I, Br or Cl.

[0047] As a preferred embodiment of the present invention, the stoichiometric ratio of the raw materials Li2S, P2S5 and LiX is based on the desired product Li 7-x PS 6-x Cl x Calculation shows that 0.5≤x≤2, where x can be 0.5, 1, 1.5 or 2, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0048] As a preferred embodiment of the present invention, the solvent includes any one of xylene, toluene, n-heptane or anisole, or a combination of at least two thereof.

[0049] In the present invention, the solvent used is a non-polar or weakly polar solvent. If a polar solvent is used, the water molecules or solvent molecules in the polar solvent may attack the PS bonds, resulting in the decomposition of the sulfide solid electrolyte.

[0050] As a preferred embodiment of the present invention, the ratio of the amount of the solvent to the total mass of the raw materials Li2S, P2S5 and LiX is (1-10):1, for example 1:1, 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1 or 10:1, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0051] As a preferred embodiment of the present invention, the inert atmosphere includes any one of argon atmosphere, helium atmosphere or neon atmosphere, or a combination of at least two of them.

[0052] As a preferred embodiment of the present invention, the preparation method comprises: premixing the raw materials Li2S, P2S5, LiX and a solvent and then performing segmented ball milling under an inert atmosphere.

[0053] As a preferred embodiment of the present invention, the premixing method includes magnetic stirring.

[0054] As a preferred embodiment of the present invention, the stirring rate of the magnetic stirring is 200rpm-550rpm, for example, 200rpm, 250rpm, 300rpm, 350rpm, 400rpm, 450rpm, 500rpm or 550rpm, etc., but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable. The stirring time is 8h-15h, for example, 8h, 10h, 12h, 14h or 15h, etc., but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0055] As a preferred embodiment of the present invention, the rotation speed of each ball mill in the segmented ball milling gradually increases with an increase of 100rpm-300rpm, for example, 100rpm, 130rpm, 150rpm, 170rpm, 200rpm, 230rpm, 250rpm, 270rpm or 300rpm, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0056] As a preferred embodiment of the present invention, the mass ratio of ball to material in the segmented ball milling is (4-20):1, for example 4:1, 6:1, 8:1, 10:1, 12:1, 14:1, 16:1, 18:1 or 20:1, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0057] In the present invention, when Li2S, P2S5, and LiX are pre-milled and then staged ball milled, the mass ratio of the ball to material in the staged ball milling is (5-15):1.

[0058] As a preferred embodiment of the present invention, the segmented ball milling includes a first segment ball milling and a second segment ball milling.

[0059] As a preferred embodiment of the present invention, the rotation speed of the first stage ball milling is 200rpm-300rpm, for example, 200rpm, 220rpm, 240rpm, 260rpm, 280rpm or 300rpm, but is not limited to the listed values, and other values ​​not listed within the numerical range are equally applicable; the ball milling time is 3h-8h, for example, 3h, 4h, 5h, 6h, 7h or 8h, but is not limited to the listed values, and other values ​​not listed within the numerical range are equally applicable.

[0060] As a preferred embodiment of the present invention, the first stage of ball milling includes three processes of forward rotation, intermittent rotation and reverse rotation, wherein the forward rotation time is 20min-60min, for example, 20min, 30min, 40min, 50min or 60min, etc., but is not limited to the listed values, and other values ​​not listed within the numerical range are equally applicable; the intermittent time is 5min-20min, for example, 5min, 10min, 13min, 15min, 17min or 20min, etc., but is not limited to the listed values, and other values ​​not listed within the numerical range are equally applicable; the reverse time is 20min-60min, for example, 20min, 30min, 40min, 50min or 60min, etc., but is not limited to the listed values, and other values ​​not listed within the numerical range are equally applicable; the forward rotation, intermittent rotation and reverse rotation processes are performed in a cycle, and the total cumulative time is 3h-8h, for example, 3h, 4h, 5h, 6h, 7h or 8h, etc., but is not limited to the listed values, and other values ​​not listed within the numerical range are equally applicable.

[0061] As a preferred embodiment of the present invention, the rotation speed of the second ball mill is 400rpm-600rpm, for example, 400rpm, 420rpm, 440rpm, 460rpm, 480rpm, 500rpm, 520rpm, 540rpm, 560rpm, 580rpm or 600rpm, but is not limited to the listed values, and other values ​​not listed within the numerical range are equally applicable; the ball milling time is 10h-27h, for example, 10h, 13h, 15h, 17h, 20h, 23h, 25h or 27h, but is not limited to the listed values, and other values ​​not listed within the numerical range are equally applicable.

[0062] As a preferred embodiment of the present invention, the second stage of ball milling includes three processes of forward rotation, intermittent rotation and reverse rotation, wherein the forward rotation time is 20min-60min, for example, 20min, 30min, 40min, 50min or 60min, etc., but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable, and the intermittent time is 5min-20min, for example, 5min, 10min, 13min, 15min, 17min or 20min, etc., but is not limited to the listed values, and the numerical range is Other unlisted values ​​are also applicable. The reversal time is 20min-60min, for example 20min, 30min, 40min, 50min or 60min, but is not limited to the listed values. Other unlisted values ​​within this numerical range are also applicable. The forward, intermittent and reverse processes are cyclically performed, and the total cumulative time is 10h-27h, for example 10h, 13h, 15h, 17h, 20h, 23h, 25h or 27h, but is not limited to the listed values. Other unlisted values ​​within this numerical range are also applicable.

[0063] The present invention adopts segmented ball milling, especially speed-increasing ball milling as opposed to ordinary uniform-speed ball milling and speed-reducing ball milling. The slow ball milling in the early stage can make the product mixing more uniform, and the fast ball milling in the later stage promotes rapid reaction, thereby improving the energy utilization rate of ball milling, reducing side reactions, and increasing the proportion of crystalline products, thereby improving ionic conductivity.

[0064] At the same time, the forward, intermittent and reverse rotation modes are used in different stages, which is conducive to uniform mixing of the reactant components and reduces the generation of by-products.

[0065] As a preferred embodiment of the present invention, the drying is carried out under an inert atmosphere, and the drying temperature is less than 150°C, for example, 140°C, 120°C, 100°C, 80°C or 60°C, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable; drying is carried out until the solvent residue is less than 200ppm.

[0066] As a preferred embodiment of the present invention, the inert atmosphere includes any one of argon atmosphere, helium atmosphere or neon atmosphere, or a combination of at least two of them.

[0067] During the drying process, the solvent can be recycled for secondary use.

[0068] As a preferred embodiment of the present invention, the sintering is carried out under an inert atmosphere, and the sintering temperature is 400°C-550°C, for example, 400°C, 420°C, 440°C, 460°C, 480°C, 500°C, 520°C or 550°C, but are not limited to the listed values, and other unlisted values ​​within the numerical range are equally applicable; the sintering time is 10h-20h, for example, 10h, 12h, 14h, 16h, 18h or 20h, but are not limited to the listed values, and other unlisted values ​​within the numerical range are equally applicable.

[0069] As a preferred embodiment of the present invention, the inert atmosphere includes any one of argon atmosphere, helium atmosphere or neon atmosphere, or a combination of at least two of them.

[0070] In a second aspect, a specific embodiment of the present invention provides a sulfide solid electrolyte, which is prepared by the above-mentioned preparation method.

[0071] The following are typical but non-limiting embodiments of the present invention:

[0072] Embodiment 1:

[0073] This embodiment provides a method for preparing a sulfide solid electrolyte, the preparation method comprising:

[0074] (1) The raw materials Li2S, P2S5 and LiCl are added to a ball mill according to the stoichiometric ratio of 4:1:3, wherein the ball-to-material mass ratio is 6:1, and then n-heptane solvent is added in a total mass ratio of 2:1 to Li2S, P2S5 and LiCl for segmented ball milling under an argon atmosphere, wherein the speed of the first stage of ball milling is 200 rpm, wherein the forward rotation is 30 min, the interval is 5 min, and the reverse rotation is 30 min, and the forward rotation, interval and reverse rotation process are repeated, and the cumulative ball milling time is 5 h; the speed of the second stage of ball milling is 500 rpm, wherein the forward rotation is 30 min, the interval is 5 min, and the reverse rotation is 30 min, and the forward rotation, interval and reverse rotation process are repeated, and the cumulative ball milling time is 10 h;

[0075] (2) The ball-milled material was dried in a vacuum drying oven at 80°C, transferred to an alumina crucible after drying, and sintered at 460°C for 15 h to obtain a sulfide solid electrolyte.

[0076] Embodiment 2:

[0077] The present embodiment provides a method for preparing a sulfide solid electrolyte, which is the same as that of Example 1, except that: in step (1), the rotation speed of the first ball milling is 300 rpm, and the forward rotation is set to 30 min, the rest is set to 5 min, and the reverse rotation is set to 30 min. The forward rotation, rest and reverse rotation processes are repeated, and the cumulative ball milling time is 5 h; the rotation speed of the second ball milling is 550 rpm, and the forward rotation is set to 30 min, the rest is set to 10 min, and the reverse rotation is set to 30 min. The forward rotation, rest and reverse rotation processes are repeated, and the cumulative ball milling time is 15 h.

[0078] Embodiment 3:

[0079] This embodiment provides a method for preparing a sulfide solid electrolyte, which is the same as that of Example 1, except that: in step (1), the raw materials Li2S, P2S5 and LiCl are mixed according to a stoichiometric ratio of 4:1:3, and then mixed with an n-heptane solvent having a total mass ratio of Li2S, P2S5 and LiCl of 2:1, and then magnetically stirred at a speed of 200 rpm for 10 hours, and then segmented ball milling is performed under an inert atmosphere.

[0080] Embodiment 4:

[0081] The present embodiment provides a method for preparing a sulfide solid electrolyte, which is the same as that of Example 1, except that: in step (1), the mass ratio of ball to material is 9:1, and the total mass ratio of n-heptane solvent to Li2S, P2S5 and LiCl is 1.5:1; the rotation speed of the first stage of the ball milling in the segmented ball milling is 250 rpm, with a forward rotation of 30 min, a rest of 5 min, and a reverse rotation of 30 min. The forward rotation, rest and reverse rotation processes are repeated, and the cumulative ball milling time is 5 h; the rotation speed of the second stage of the ball milling is 600 rpm, with a forward rotation of 30 min, a rest of 10 min, and a reverse rotation of 30 min. The forward rotation, rest and reverse rotation processes are repeated, and the cumulative ball milling time is 15 h; and in step (2), sintering is performed at 460° C. for 10 h.

[0082] Embodiment 5:

[0083] The present embodiment provides a method for preparing a sulfide solid electrolyte, which is the same as that of Example 1, except that: in step (1), the raw materials Li2S, P2S5 and LiCl are added to a ball mill according to a stoichiometric ratio of 4:1:3, and ball milled for 5 hours at a ball-to-material ratio of 6:1. Then, an n-heptane solvent having a total mass ratio of Li2S, P2S5 and LiCl of 4:1 is added to carry out segmented ball milling under an argon atmosphere, wherein the rotation speed of the first stage of ball milling is 300 rpm, forward rotation for 30 minutes, rest for 5 minutes, and reverse rotation for 30 minutes, and the forward rotation, rest and reverse rotation processes are repeated, and the cumulative ball milling time of the cycle is 3 hours; the rotation speed of the second stage of ball milling is 500 rpm, forward rotation for 30 minutes, rest for 10 minutes, and reverse rotation for 30 minutes, and the forward rotation, rest and reverse rotation processes are repeated, and the cumulative ball milling time of the cycle is 10 hours.

[0084] Comparative Example 1:

[0085] This comparative example provides a method for preparing a sulfide solid electrolyte, which is the same as that of Example 1, except that the sintering temperature in step (2) is 300°C.

[0086] Comparative Example 2:

[0087] This comparative example provides a method for preparing a sulfide solid electrolyte, which is the same as that of Example 1, except that the solvent used in step (1) is anhydrous ethanol.

[0088] Comparative Example 3:

[0089] This comparative example provides a method for preparing a sulfide solid electrolyte, the preparation method comprising:

[0090] The raw materials Li2S, P2S5 and LiCl were added into a ball mill in a stoichiometric ratio of 4:1:3, with a ball-to-material mass ratio of 6:1. After ball milling at a speed of 510 rpm for 20 h under an argon atmosphere, the sulfide solid electrolyte was obtained after sintering at 460 °C for 10 h.

[0091] Comparative Example 4:

[0092] This comparative example provides a method for preparing a sulfide solid electrolyte, the preparation method comprising:

[0093] The raw materials Li2S, P2S5 and LiCl were added into a ball mill in a stoichiometric ratio of 4:1:3, with a ball-to-material mass ratio of 6:1. The ball mill was performed at a speed of 510 rpm for 10 hours under an argon atmosphere. The ball mill was opened every 2 hours to crush the reactants and mix them evenly with the grinding balls. The milled material was sintered at 460°C for 10 hours to obtain a sulfide solid electrolyte.

[0094] Comparative Example 5:

[0095] This comparative example provides a method for preparing a sulfide solid electrolyte, which is the same as that of Example 1, except that the ball milling in step (1) is a one-step ball milling, the ball milling speed is 500 rpm, and the ball milling time is 15 h.

[0096] Comparative Example 6:

[0097] This comparative example provides a method for preparing a sulfide solid electrolyte, which is the same as that of Example 1, except that: in step (1), the rotation speed of the first ball milling is 500 rpm; and the rotation speed of the second ball milling is 300 rpm.

[0098] The sulfide solid electrolytes prepared in Examples 1-5 and Comparative Examples 1-6 were tested for ionic conductivity. The test conditions were as follows: 0.13 g of electrolyte powder was taken and pressed into a powder tabletting mold to a value of S = 0.785 cm 2 The sample body impedance (R e ), using the formula σ=d / (R e *S) to calculate its ionic conductivity σ, where d is the thickness of the sample being tested. The test results are shown in Table 1.

[0099] Table 1: Test results of Examples 1-5 and Comparative Examples 1-6

[0100]

[0101] As can be seen from Table 1, the present invention adopts segmented ball milling, especially speed-increasing ball milling, compared with ordinary uniform-speed ball milling and speed-reducing ball milling, the speed-increasing ball milling raw materials can be mixed evenly under low-speed conditions, and the reaction can be promoted under high-speed conditions. It can achieve higher crystalline product generation under low energy consumption conditions, thereby obtaining a sulfide solid electrolyte with high ionic conductivity.

[0102] The applicant declares that the present invention illustrates the detailed process equipment and process flow of the present invention through the above-mentioned embodiments, but the present invention is not limited to the above-mentioned detailed process equipment and process flow, that is, it does not mean that the present invention must rely on the above-mentioned detailed process equipment and process flow to be implemented. Those skilled in the art should understand that any improvement of the present invention, equivalent replacement of various raw materials of the product of the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A method for preparing a sulfide solid electrolyte, characterized in that: The preparation method comprises the following steps: The raw materials Li2S, P2S5, LiX and solvent are ball-milled in sections under an inert atmosphere, and then dried and sintered in sequence to obtain a sulfide solid electrolyte; Wherein, the segmented ball milling includes at least two segments of ball milling.

2. The preparation method according to claim 1, characterized in that: Before the raw materials Li2S, P2S5, LiX and solvent are subjected to segmented ball milling under an inert atmosphere, the process further comprises: Pre-ball milling any one or at least two of Li2S, P2S5 or LiX; The ball-to-material mass ratio of the pre-ball milling is (5-10):1, the ball milling time is 1h-10h, and the ball milling speed is 300rpm-900rpm.

3. The preparation method according to claim 1, characterized in that: X in the raw material LiX is any one of I, Br or Cl; Preferably, the stoichiometric ratio of the raw materials Li2S, P2S5 and LiX is based on the desired product Li 7-x PS 6-x Cl x Calculation shows that 0.5≤x≤2.

4. The preparation method according to claim 1, characterized in that: The solvent includes any one of xylene, toluene, n-heptane or anisole, or a combination of at least two thereof; Preferably, the ratio of the amount of the solvent to the total mass of the raw materials Li2S, P2S5 and LiX is (1-10):1; Preferably, the inert atmosphere includes any one of an argon atmosphere, a helium atmosphere or a neon atmosphere, or a combination of at least two of them.

5. The preparation method according to claim 1, characterized in that: The preparation method comprises: premixing raw materials Li2S, P2S5, LiX and a solvent and then performing segmented ball milling under an inert atmosphere; Preferably, the premixing method comprises magnetic stirring; Preferably, the stirring rate of the magnetic stirring is 200 rpm-550 rpm, and the stirring time is 8 h-15 h.

6. The preparation method according to claim 1, characterized in that: The speed of each ball mill in the segmented ball milling is gradually increased, with an increase of 100 rpm to 300 rpm; Preferably, the mass ratio of ball to material in the segmented ball milling is (4-20):

1.

7. The preparation method according to claim 1, characterized in that: The segmented ball milling includes a first segment ball milling and a second segment ball milling; Preferably, the rotation speed of the first stage of ball milling is 200rpm-300rpm, and the ball milling time is 3h-8h; Preferably, the first stage of ball milling includes three processes of forward rotation, intermittent rotation and reverse rotation, wherein the forward rotation time is 20min-60min, the intermittent rotation time is 5min-20min, the reverse rotation time is 20min-60min, and the forward rotation, intermittent rotation and reverse rotation processes are performed in a cycle, and the total cumulative time is 3h-8h; Preferably, the rotation speed of the second stage ball milling is 400 rpm-600 rpm, and the ball milling time is 10 h-27 h; Preferably, the second stage of ball milling includes three processes of forward rotation, intermittent rotation and reverse rotation, wherein the forward rotation time is 20min-60min, the intermittent time is 5min-20min, the reverse rotation time is 20min-60min, and the forward rotation, intermittent rotation and reverse rotation processes are repeated, and the total accumulated time is 10h-27h.

8. The preparation method according to claim 1 or 2, characterized in that: The drying is carried out under an inert atmosphere, the drying temperature is less than 150° C., and the drying is carried out until the residual solvent content is less than 200 ppm; Preferably, the inert atmosphere includes any one of an argon atmosphere, a helium atmosphere or a neon atmosphere, or a combination of at least two of them.

9. The preparation method according to claim 1 or 2, characterized in that: The sintering is carried out in an inert atmosphere, the sintering temperature is 400° C.-550° C., and the sintering time is 10 h-20 h; Preferably, the inert atmosphere includes any one of an argon atmosphere, a helium atmosphere or a neon atmosphere, or a combination of at least two of them.

10. A sulfide solid electrolyte, characterized in that: The sulfide solid electrolyte is prepared by the preparation method according to any one of claims 1 to 9.

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