Sulfide solid electrolyte material with excellent environmental stability and preparation method thereof

Abstract

The invention discloses a sulfide solid electrolyte material with excellent environmental stability, which comprises a core layer and a shell layer, and the shell layer coats the core layer; the core layer is mainly composed of a sulfide solid electrolyte matrix; the shell layer is mainly composed of a modified polymer, the modified polymer comprises a hydrophobic chain segment and a coordination functional group, and the coordination functional group is only sulfydryl; the composition of the core layer and the shell layer has the characteristics that after the composition is placed in air with the relative humidity of 40-85% and the temperature of 25 DEG C for 24 hours, the release amount of hydrogen sulfide is smaller than or equal to 0.08 mg / g; under the condition that the initial ionic conductivity is greater than or equal to 1 * 10 <-3 > S / cm, the retention rate of the ionic conductivity is greater than or equal to 90%; the mass change rate is not more than 2%. The sulfydryl in the modified polymer has strong reducibility and can preferentially react with oxygen groups in air to generate stable S-S bonds, so that oxidation is prevented; sulfydryl and Li < + > and P < 5 + > on the surface of the sulfide form stable coordinate bonds, so that the bonding strength is greatly improved; on the other hand, the hydrophobic chain segment forms a compact molecular barrier, so that the water-oxygen permeation rate is greatly reduced.

Description

Technical Field

[0001] This invention relates to the field of solid-state battery technology, and more specifically, to a sulfide solid electrolyte material with excellent environmental stability and its preparation method. Background Technology

[0002] Against the backdrop of rapid iteration in the new energy industry, solid-state batteries have become a focus of attention in the energy storage field due to their core advantages such as high safety performance, ultra-long cycle life, and high energy density. Among the key components of solid-state batteries, sulfide solid electrolytes are particularly noteworthy for their high ion conductivity (up to 1×10⁻⁶ at room temperature). -3 ~1×10 -2 With advantages such as high S / cm and good compatibility with lithium metal anodes, solid-state battery technology has become one of the core directions of current research and development. However, it should be noted that sulfide solid electrolytes prepared using traditional processes generally suffer from poor air stability, which directly leads to many limitations in the large-scale production, storage, and practical assembly applications of all-solid-state batteries, greatly hindering the industrialization process of all-solid-state battery technology.

[0003] Traditional sulfide solid electrolytes (such as Li3PS4 and Li6PS5Cl) have extremely poor chemical stability, and the sulfur on their surface... 2- PS4 3- These reactive groups readily react violently with moisture (H2O) and oxygen (O2) in the air: on the one hand, moisture reacts with sulfur... 2- The reaction produces toxic hydrogen sulfide (H2S) gas, which not only pollutes the production environment but also causes the electrolyte crystal structure to collapse; on the other hand, oxygen oxidizes PS4. 3- Tetrahedrals generate byproducts such as Li2S and Li3PO4, which have no ion conductivity, causing a significant decrease in the electrolyte's ionic conductivity (e.g., the retention rate is often less than 50% after 24 hours).

[0004] Furthermore, from a practical application perspective, the poor air stability of sulfide electrolytes poses a significant challenge to their production, storage, and use. Production requires strict inert gas protection or operation in a dry chamber, increasing cost and complexity. Storage also necessitates a sealed, dry environment; otherwise, performance will gradually degrade. During battery assembly and use, trace amounts of moisture and oxygen can enter the battery and react with the sulfide electrolyte, leading to performance degradation and shortened battery life. Therefore, improving the air stability of sulfide solid-state electrolytes has become a pressing issue in the field of solid-state batteries.

[0005] Among existing modification technologies, surface coating is the main means to improve the stability of sulfide electrolytes, but it has obvious drawbacks: when using oxides (such as Al2O3, SiO2) for coating, although water and oxygen can be physically blocked, the coating layer and electrolyte interface are only physically adsorbed, and the binding force is weak, making it easy to fall off during battery cycling; when using a single hydrophobic polymer (such as pure PVDF, PEO) for coating, although water contact can be reduced, there is a lack of chemical interaction with the electrolyte surface, resulting in high interfacial impedance and inability to resist the oxidation of the electrolyte by oxygen; when using small molecule thiols for modification, although they can be bound through thiol coordination, small molecules are volatile and have poor long-term stability, making it difficult to meet the needs of large-scale production.

[0006] Therefore, there is an urgent need to develop a sulfide solid electrolyte material that combines the triple functions of "strong chemical bonding", "efficient water and oxygen barrier" and "active anti-oxidation". By designing the material structure, its environmental stability can be fundamentally improved. At the same time, a simple and efficient preparation method can be provided to promote the industrialization of all-solid-state lithium batteries. Summary of the Invention

[0007] The main objective of this invention is to overcome the shortcomings of existing sulfide solid electrolytes, such as poor environmental stability and limited functionality, by using a core-shell structure design with a sulfide electrolyte as the core and a modified polymer containing thiol groups (-SH) as the shell. This achieves a synergistic effect of "coordination-enhanced binding, hydrophobic barrier against water and oxygen, and active antioxidant activity of thiol groups." Based on this, the invention provides a sulfide solid electrolyte material with excellent environmental stability.

[0008] Another object of the present invention is to provide a method for preparing the material.

[0009] Another object of the present invention is to provide another method for preparing the above-mentioned material.

[0010] It should be noted that the preparation method of the present invention can ensure that the material can be mass-produced and has stable performance.

[0011] To achieve the above objectives, the specific technical solution adopted by the present invention is as follows:

[0012] The present invention discloses a sulfide solid electrolyte material with excellent environmental stability, wherein the material has a core-shell structure and comprises:

[0013] Core layer: Sulfide solid electrolyte matrix, selected from Li3PS4 and Li7P3S 11 Li 10 GeP2S 12 Li6PS5X (where X is Cl, Br, I, or F), Li 9.54 Si 1.74 P1.44 S 11.7 Cl 0.6 At least one of them, wherein the average particle size of the core layer is 100 nm to 5 μm, ensuring high ion conductivity;

[0014] Shell: A modified polymer layer covering the surface of the core layer, with a thickness of 5 nm to 200 nm. The modified polymer must simultaneously meet the following requirements:

[0015] (1) Contains hydrophobic segments: selected from at least one of polyethylene oxide (PEO) segments, polyvinylidene fluoride (PVDF) segments, polytetrafluoroethylene (PTFE) segments, polycaprolactone (PCL) segments, and polylactic acid (PLA) segments, which physically block water and oxygen permeation through hydrophobic effects;

[0016] (2) Contains coordinating functional groups: Only thiol groups (-SH) are retained, and the thiol groups interact with the Li on the core surface. + P 5+ Formation of stable coordination bonds (such as -S-Li) + -SP 5+ This enhances the bonding strength between the shell and the core, while the strong reducing power of thiol groups can preferentially react with oxygen and reactive oxygen free radicals in the air to generate stable disulfides (SS bonds), thus achieving active antioxidant protection.

[0017] The core performance indicators of this material are as follows: After being placed in air with a relative humidity of 40%~85% and a temperature of 25℃ for 24 hours, ① the hydrogen sulfide release is ≤0.08mg / g; ② the ionic conductivity retention rate is ≥90% (initial ionic conductivity ≥1×10⁻⁶). -3 ③ Mass change rate ≤ 2% (no obvious moisture absorption).

[0018] The principle behind improving the environmental stability of sulfide solid electrolyte materials is as follows: the thiol (-SH) groups in the modified polymer have strong reducing properties and can preferentially react with oxidizing substances in the air to exert a reducing protective effect; the hydrophobic PEO, PVDF, PTFE, PCL, and PLA backbones can form a physical barrier to reduce water and oxygen permeation; and the thiol (-SH) groups can coordinate with metal cations on the electrolyte surface, while the flexibility of the polymer chains can adapt to the interface morphology between the electrolyte and the electrode, maintaining the stability of the interface contact.

[0019] Another object of the present invention is to provide a method for preparing the above-mentioned sulfide solid electrolyte material:

[0020] The preparation method includes spray drying, specifically as follows:

[0021] This preparation method achieves uniform coating of modified polymer on the surface of sulfide particles through atomization-rapid drying, and the steps are as follows:

[0022] S1. Preparation of the spray-drying precursor solution:

[0023] Sulfide solid electrolyte powder, mercapto-containing modified polymer, and optional dispersant are added to an organic solvent and stirred at less than 500 r / min for 1 to 4 hours at 25℃ to 60℃. Then, the mixture is ultrasonically dispersed to obtain a uniformly dispersed, non-agglomerated spray-drying precursor liquid.

[0024] The sulfide solid electrolyte powder is selected from Li3PS4 and Li7P3S. 11 Li 10 GeP2S 12 Li6PS5X (where X is Cl, Br, I, or F), Li 9.54 Si 1.74 P 1.44 S 11.7 C 0.6 At least one of them, with an average particle size of 100 nm to 5 μm;

[0025] The modified polymer is selected from at least one of thiol-modified polyethylene oxide (PEO-SH), thiol-modified polyvinylidene fluoride (PVDF-SH), thiol-modified polytetrafluoroethylene (PTFE-SH), thiol-modified polycaprolactone (PCL-SH), and thiol-modified polylactic acid (PLA-SH).

[0026] The dispersant is selected from polyvinylpyrrolidone (PVP), sodium dodecylbenzenesulfonate (SDBS), polyethylene glycol (PEG), and triblock copolymer F127 (EO). 106 PO 70 EO 106 At least one of the following;

[0027] The organic solvent is selected from at least one of N,N-dimethylformamide (DMF), N-methylpyrrolidone (NMP), tetrahydrofuran (THF), and dichloromethane (DCM) to ensure that the modified polymer is completely dissolved and does not react with the sulfide solid electrolyte.

[0028] The mass ratio of the sulfide solid electrolyte powder to the modified polymer is 5-20:1 to ensure that the shell thickness is controllable.

[0029] The amount of dispersant added is 0.1-2% of the mass of the sulfide solid electrolyte powder to prevent sulfide particles from agglomerating.

[0030] The liquid-solid content of the spray-drying precursor is 5wt%~20wt%, which balances atomization efficiency and coating uniformity.

[0031] S2. Spray-dried coating:

[0032] The spray-drying precursor liquid obtained in step S1 is passed into a spray drying device and spray-dried under inert gas protection to obtain the polymer-sulfide solid electrolyte composite primary product. During this process, the solvent in the tiny droplets evaporates rapidly, and the modified polymer is uniformly coated on the surface of the sulfide particles due to surface tension, forming a "core-shell" structure primary product.

[0033] The atomizer of the spray drying equipment is a centrifugal atomizer with a rotation speed of 10,000 to 30,000 r / min or a centrifugal atomizer with an atomization pressure of 0.5 to 2 MPa, to ensure that the precursor liquid is atomized into tiny droplets of 5 to 50 μm.

[0034] The inlet air temperature of the spray drying equipment is 80-150℃, which rapidly evaporates the solvent and avoids droplet aggregation;

[0035] The outlet air temperature of the spray drying equipment is 40-80℃, which is lower than the decomposition temperature of the modified polymer, ensuring that the thiol groups are not destroyed;

[0036] The feed rate of the spray drying equipment is 5~20mL / min, which matches the atomization and drying rates to avoid the sticking of undried droplets.

[0037] The inert gas is argon or nitrogen, and the flow rate of the inert gas is 10-30 m³ / h;

[0038] S3. Vacuum Post-treatment

[0039] The polymer-sulfide solid electrolyte composite primary product obtained in step S2 is placed in a vacuum drying oven to remove residual solvent, thereby obtaining the target sulfide solid electrolyte material.

[0040] The heating rate of the vacuum drying process is 2-5℃ / min to avoid excessively rapid heating that could cause the composite particles to crack.

[0041] Another object of the present invention is to provide a solution coating-drying method for preparing the above-mentioned materials:

[0042] This preparation method achieves uniform coating of modified polymers on the surface of sulfide solid electrolytes through a process of "polymer solution preparation - directional adsorption coating - separation and purification - vacuum drying". The specific steps are as follows:

[0043] S1. Preparation of modified polymer solution

[0044] Select a modified polymer, add it to an organic solvent, and stir at 25℃~50℃ and a stirring rate of 200~400r / min for 2~3h until the modified polymer is completely dissolved and there are no visible particles in the solution, to obtain a modified polymer solution with a mass concentration of 0.5%~5%.

[0045] The modified polymer is selected from at least one of thiol-modified polyethylene oxide (PEO-SH), thiol-modified polyvinylidene fluoride (PVDF-SH), thiol-modified polytetrafluoroethylene (PTFE-SH), thiol-modified polycaprolactone (PCL-SH), and thiol-modified polylactic acid (PLA-SH).

[0046] The organic solvent must meet the following conditions: ① be able to completely dissolve the modified polymer; ② not react chemically with the sulfide solid electrolyte; ③ have a boiling point of 60℃~150℃, which facilitates subsequent vacuum drying removal; preferably at least one of N,N-dimethylformamide (DMF), N-methylpyrrolidone (NMP), and tetrahydrofuran (THF);

[0047] S2. Directional adsorption and coating reaction

[0048] The sulfide solid electrolyte powder is slowly added to the modified polymer solution obtained in step S1 at a mass ratio of sulfide solid electrolyte powder to modified polymer of 8~15:1. The feeding rate is controlled at 0.5~2g / min to avoid excessive local concentration leading to particle agglomeration. After the feeding is completed, the mixture is transferred to a constant temperature water bath reactor and stirred at 25℃~50℃ and a stirring rate of 300~500r / min for 2~6h to ensure that the modified polymer has been completely adsorbed on the sulfide surface, thus obtaining the coated intermediate.

[0049] Optionally, if it is necessary to further improve the uniformity of coating, ultrasonic assistance can be introduced during the stirring process. The ultrasonic power is 100~200W, the ultrasonic time is 30~60min, and the ultrasonic and stirring are alternated (e.g., 10min of ultrasonication + 20min of stirring is one cycle), and the ultrasonic cavitation effect is used to disperse the micro agglomerates.

[0050] S3. Solid-liquid separation and purification

[0051] The coated intermediate obtained in step S2 is transferred to a centrifuge tube and centrifuged for 10 to 15 minutes at a speed of 5000 to 8000 r / min and a temperature of 25℃ to 30℃ to completely precipitate the sulfide particles adsorbed with the modified polymer and separate and remove the clear liquid containing free polymer from the upper layer.

[0052] Add the same organic solvent as in step S1 to the centrifuge tube, the amount of which is 1 / 3 to 1 / 2 of the initial polymer solution volume. Stir at 3000 to 5000 r / min for 5 to 10 min to wash. Then repeat the centrifugation operation. Wash in this way 2 to 3 times to obtain the purified solid product.

[0053] S4. Vacuum drying and characterization

[0054] The purified solid product obtained in step S3 was transferred to a vacuum drying oven and pre-dried at 60℃~80℃ and vacuum degree ≤-0.08MPa for 2~4h to remove most of the surface adsorbed solvent. Then the temperature was raised to 80℃~100℃ and the vacuum degree was maintained at ≤-0.1MPa for 6~8h. After cooling to room temperature, it was taken out to obtain a sulfide solid electrolyte material with a "core-shell" structure.

[0055] Compared with the prior art, the present invention has the following advantages:

[0056] First, environmental stability is significantly improved: On the one hand, the thiol groups (-SH) in the modified polymer have strong reducing properties and can preferentially react with oxygen and reactive oxygen free radicals in the air to form stable SS bonds, "sacrificing" themselves to protect the core layer sulfide from oxidation; the thiol groups react with the Li on the sulfide surface... + P 5+ Stable coordination bonds are formed, greatly enhancing the shell bonding strength; on the other hand, hydrophobic segments (such as PVDF and PTFE) form a dense molecular barrier, significantly reducing the water and oxygen permeation rate.

[0057] Second, it has excellent interface performance: the flexibility of the modified polymer can alleviate the interfacial stress between the electrolyte and the electrode during battery cycling (such as particle compression caused by the volume change of the lithium metal anode), and prevent the electrolyte from cracking; at the same time, the presence of thiol groups allows the shell and core layers to be chemically coordinated rather than simply physically adsorbed, which can reduce the interfacial impedance.

[0058] Third, the preparation method is flexible and efficient: the core spray drying method can realize continuous production, the product particles are spherical (average particle size 1~10μm) and have good dispersibility, and the production efficiency is 3~5 times higher than the traditional solution method; at the same time, the supporting solution coating method can be adapted to different batches and shell thickness requirements, and has a wide range of applications. Attached Figure Description

[0059] Figure 1 This is a schematic diagram of the structure of the sulfide solid electrolyte in a preferred embodiment of the present invention.

[0060] Figure labeling: 1-core layer; 2-shell layer; 21-hydrophobic segment; 22-coordination functional group. Detailed Implementation

[0061] The present invention will be further explained and described below through specific embodiments. It should be understood that the purpose of the following embodiments is to make the technical solution of the present invention clearer and easier to understand, and does not limit the scope of protection of the claims.

[0062] The present invention will be further described below through specific embodiments.

[0063] Example 1

[0064] A method for preparing PEO-SH / Li3PS4 composites by spray drying includes the following steps:

[0065] S1. Preparation of spray drying precursor liquid: Weigh 10g of Li3PS4 powder with an average particle size of 200nm, 1g of PEO-SH, and 0.05g of PVP, add them to 89g of DMF, stir at 300r / min for 2h at 40℃, and then ultrasonically disperse at 200W power for 1h to obtain a uniform precursor liquid with a solid content of 10wt%.

[0066] S2. Spray drying coating: Centrifugal spray drying equipment was used, with argon gas (flow rate 20m³ / h) for protection, and the inlet air temperature was set to 120℃, the outlet air temperature to 60℃, the atomizer speed to 20000r / min, and the feed rate to 10mL / min for spray drying to obtain the primary product of the complex.

[0067] S3. Vacuum post-treatment: The initial product was placed in a vacuum drying oven and heated to 80℃ at a rate of 3℃ / min. It was then dried under a vacuum of -0.1MPa for 8 hours to obtain the PEO-SH / Li3PS4 composite, in which the D50 particle size of the core layer 1 was 2.1μm and the thickness of the shell layer 2 was 20nm.

[0068] Example 2

[0069] A method for preparing PVDF-SH / Li6PS5Cl composites using spray drying includes the following steps:

[0070] S1. Preparation of spray drying precursor liquid: Weigh 15g of Li6PS5Cl powder with an average particle size of 300nm, 1g of PVDF-SH, and 0.045g of F127 + 0.055g of PVP compound dispersant, add them to 84g of NMP, stir at 350r / min for 2.5h at 45℃, and then ultrasonically disperse at 250W power for 1.2h to obtain a precursor liquid with a solid content of 15wt%.

[0071] S2. Spray drying coating: Centrifugal spray drying equipment is used, and nitrogen gas is introduced (flow rate 22m). ³ / h), set the inlet air temperature to 130℃, the outlet air temperature to 65℃, the atomizer speed to 25000r / min, and the feed rate to 12mL / min to obtain the initial product of the complex;

[0072] S3. Vacuum post-treatment: The initial product was placed in a vacuum drying oven and heated to 90℃ at a rate of 4℃ / min. It was then dried under a vacuum of -0.095MPa for 10h to obtain the PVDF-SH / Li6PS5Cl composite, in which the D50 particle size of the core layer 1 was 1.3μm and the thickness of the shell layer 2 was 34nm.

[0073] Example 3

[0074] A method for preparing PCL-SH / Li using solution coating-drying 10 GeP2S 12 The method for the complex includes the following steps:

[0075] S1. Preparation of polymer solution: Weigh 0.8g PCL-SH and add it to 99.2g NMP. Stir at 300r / min for 3h at 35℃ to obtain a PCL-SH solution with a mass concentration of 0.8%.

[0076] S2. Targeted adsorption and coating: Weigh 12g Li 10 GeP2S 12 The powder was added to the above solution at a rate of 0.8 g / min, and then transferred to a constant temperature water bath reactor (40℃). The mixture was stirred at 400 r / min for 4 h, with alternating "ultrasound for 10 min + stirring for 20 min" (ultrasound power 150 W).

[0077] S3. Solid-liquid separation and purification: Centrifuge the mixture at 8000 r / min for 12 min, collect the precipitate, wash twice with NMP (30 mL each time), and centrifuge to separate;

[0078] S4. Vacuum drying: The purified precipitate was pre-dried at 70℃ and -0.08MPa for 3 hours, then heated to 90℃ and dried at -0.1MPa for 7 hours to obtain PCL-SH / Li 10 GeP2S 12 The complex has a core layer 1 with a D50 particle size of 0.95 μm and a shell layer 2 with a thickness of 53 nm.

[0079] Example 4

[0080] A method for preparing PTFE-SH / Li using spray drying 9.54Si 1.74 P 1.44 S 11.7 C l0.6 The method for the complex includes the following steps:

[0081] S1. Preparation of precursor solution: Weigh 12g Li 9.54 Si 1.74 P 1.44 S 11.7 C l0.6 Powder (average particle size 400nm), 1g PTFE-SH, and 0.06g PEG were added to 87g THF and stirred at 350r / min for 3h at 50℃. Then, the mixture was ultrasonically dispersed at 280W for 1.5h to obtain a precursor solution with a solid content of 13wt%.

[0082] S2. Spray drying coating: A pressure spray dryer (atomization pressure 1.2MPa) was used, nitrogen gas was introduced (flow rate 25m³ / h), and the inlet air temperature was set to 140℃, the outlet air temperature to 70℃, and the feed rate to 15mL / min to obtain the initial product of the complex.

[0083] S3. Vacuum post-treatment: The primary product was heated to 100℃ at a rate of 5℃ / min and dried under a vacuum of -0.098MPa for 9 hours to obtain PTFE-SH / Li. 9.54 Si 1.74 P 1.44 S 11.7 C l0.6 The complex has a core layer 1 with a D50 particle size of 0.5 μm and a shell layer 2 with a thickness of 94 nm.

[0084] Example 5

[0085] A method for preparing PLA-SH / Li7P3S using solution coating-drying 11 The method for the complex includes the following steps:

[0086] S1. Preparation of polymer solution: Weigh 0.6g PLA-SH and add it to 99.4g DMF. Stir at 320r / min for 2.5h at 45℃ to obtain a PLA-SH solution with a mass concentration of 0.6%.

[0087] S2. Targeted adsorption and coating: Weigh 9g of Li7P3S 11The powder (average particle size 300 nm) was added to the above solution at a rate of 0.6 g / min, transferred to a constant temperature water bath reactor (45 °C), and stirred at 450 r / min for 5 h, during which "ultrasound for 15 min + stirring for 25 min" was alternated (ultrasound power 180 W).

[0088] S3. Solid-liquid separation and purification: Centrifuge the mixture at 7000 r / min for 14 min, collect the precipitate, wash it three times with DMF (25 mL each time), and centrifuge to separate it;

[0089] S4. Vacuum drying: The purified precipitate was pre-dried at 75℃ and -0.085MPa for 3.5h, and then dried at 95℃ and -0.1MPa for 6.5h to obtain PLA-SH / Li7P3S. 11 The complex has a core layer 1 with a D50 particle size of 3.5 μm and a shell layer 2 with a thickness of 126 nm.

[0090] Example 6

[0091] A method for preparing PVDF-SH / Li6PS5Br composites using spray drying includes the following steps:

[0092] S1. Preparation of precursor solution: Weigh 8g Li6PS5Br powder (average particle size 250nm), 1g PVDF-SH, and 0.04g F127, add them to 91g NMP, stir at 280r / min for 2h at 35℃, and then ultrasonically disperse at 220W power for 1h to obtain a precursor solution with a solid content of 8wt%;

[0093] S2. Spray drying coating: A centrifugal spray dryer (18000 r / min) was used, argon gas was introduced (flow rate 18 m³ / h), and the inlet air temperature was set to 110℃, the outlet air temperature to 55℃, and the feed rate to 8 mL / min to obtain the initial product of the complex.

[0094] S3. Vacuum post-treatment: The initial product was heated to 75℃ at 2℃ / min and dried under vacuum of -0.09MPa for 7h to obtain the PVDF-SH / Li6PS5Br composite, wherein the D50 particle size of the core layer 1 is 2.3μm and the thickness of the shell layer 2 is 63nm.

[0095] Example 7

[0096] A method for preparing PEO-SH / Li using solution coating-drying 10 GeP2S 12The method for the complex includes the following steps:

[0097] S1. Preparation of polymer solution: Weigh 1.2g PEO-SH and add it to 98.8g THF. Stir at 300r / min for 3h at 40℃ to obtain a PEO-SH solution with a mass concentration of 1.2%.

[0098] S2. Targeted adsorption and coating: Weigh 12g Li 10 GeP2S 12 The powder (average particle size 500 nm) was added to the above solution at a rate of 1.0 g / min, transferred to a constant temperature water bath reactor (50 °C), and stirred at 500 r / min for 6 h, during which "ultrasound for 12 min + stirring for 28 min" was alternated (ultrasound power 200 W).

[0099] S3. Solid-liquid separation and purification: Centrifuge the mixture at 8000 r / min for 15 min, collect the precipitate, wash it three times with THF (35 mL each time), and centrifuge to separate it;

[0100] S4. Vacuum drying: The purified precipitate was pre-dried at 80℃ and -0.09MPa for 4 hours, then heated to 100℃ and dried at -0.1MPa for 8 hours to obtain PEO-SH / Li. 10 GeP2S 12 The complex has a core layer 1 with a D50 particle size of 0.78 μm and a shell layer 2 with a thickness of 12 nm.

[0101] Comparative Example 1:

[0102] Unmodified sulfide solid electrolyte (Li6PS5Cl)

[0103] Performance testing was conducted using laboratory-made Li6PS5Cl powder (average particle size 300 nm, uncoated).

[0104] Comparative Example 2:

[0105] Oxide-coated sulfide electrolyte (Al2O3 / Li3PS4)

[0106] Al2O3 was coated onto the surface of Li3PS4 using the sol-gel method. This method is a typical oxide coating modification technique in the prior art. The specific steps are as follows:

[0107] Raw material pretreatment: The laboratory-made Li3PS4 powder (average particle size 200nm, purity ≥99.5%) was placed in a vacuum drying oven and dried at 80℃ and vacuum degree -0.1MPa for 6h to remove surface adsorbed water;

[0108] Preparation of sol precursor: Aluminum isopropoxide (Al(OC3H7)3) was selected as the Al2O3 source, ethanol as the solvent, and nitric acid (0.1 mol / L) as the hydrolysis catalyst. According to the molar ratio of Al(OC3H7)3: ethanol: nitric acid = 1:20:0.5, 5.2 g of aluminum isopropoxide was first dissolved in 100 mL of ethanol and stirred at 200 r / min for 30 min at 30 °C. Then, 8.7 mL of 0.1 mol / L nitric acid was added dropwise (dropping rate 1 mL / min), and stirring was continued for 2 h to obtain a transparent and homogeneous Al2O3 sol.

[0109] Dispersion and coating: Weigh 10g of pretreated Li3PS4 powder and add it to the above Al2O3 sol at a solid-liquid ratio of 1:10 (g:mL). Transfer the mixture to a constant temperature water bath reactor (35℃) and stir at 300r / min for 4h. During the stirring process, aluminum isopropoxide gradually hydrolyzes to generate Al(OH)3 and adsorbs onto the surface of Li3PS4 through hydrogen bonds to form a preliminary coating layer.

[0110] Aging treatment: After stirring, the mixture is allowed to stand at 25°C for 6 hours to age, allowing Al(OH)3 to further condense and form a stable gel layer, thus preventing the coating layer from cracking during the subsequent drying process.

[0111] Preliminary drying: The aged mixture was transferred to a rotary evaporator and rotary evaporated at 50°C and a vacuum of -0.08MPa for 2 hours to remove most of the ethanol solvent, resulting in wet powder of Al(OH)3 coated with Li3PS4.

[0112] Calcination and curing: The wet powder was placed in a tube furnace and heated to 300°C at a rate of 2°C / min under argon protection (flow rate 100 mL / min). The mixture was then calcined at this temperature for 3 hours to completely decompose Al(OH)3 into Al2O3. After cooling to room temperature, the powder was removed to obtain an Al2O3-coated Li3PS4 composite, in which the D50 particle size of the core layer was 4.5 μm and the thickness of the shell layer was 260 nm.

[0113] Comparative Example 3:

[0114] Thiol-free polymer-coated electrolyte (PVDF / Li6PS5Cl)

[0115] Pure PVDF was coated onto the surface of Li6PS5Cl using a spray drying method, with the specific steps being the same as in Example 2. The D50 particle size of the core layer was 6.2 μm, and the thickness of the shell layer was 10 nm.

[0116] Comparative Example 4:

[0117] Small molecule thiols modifying Li6PS5Cl

[0118] Li6PS5Cl powder was modified with 1,2-ethanedithiol (a small molecule thiol) as follows:

[0119] (1) Raw material pretreatment and preparation

[0120] Li6PS5Cl powder pretreatment: Weigh 10g of laboratory-made Li6PS5Cl powder (average particle size 300nm, purity ≥99.5%), place it in a vacuum drying oven, and dry it for 6h at 80℃ and vacuum degree ≤-0.1MPa to remove the moisture and residual impurities adsorbed on the powder surface.

[0121] Preparation of 1,2-ethanedithiol solution: Analytical grade 1,2-ethanedithiol was selected as the modifying agent, and anhydrous ethanol (analytical grade, water content ≤0.05%) was selected as the solvent. In a glove box, 0.5 g of 1,2-ethanedithiol was slowly added to 50 mL of anhydrous ethanol and stirred at 200 r / min for 15 min to prepare a 1% (w / w) 1,2-ethanedithiol ethanol solution.

[0122] (2) Small molecule modification reaction

[0123] Dispersion and adsorption: In a glove box, 10g of pretreated Li6PS5Cl powder was slowly added to the above 1,2-ethylenedithiol ethanol solution, with the feeding rate controlled at 0.5g / min; the mixture was transferred to a three-necked flask with a sealed cap, removed from the glove box, and stirred at 300r / min for 2h under a constant temperature water bath at 25℃.

[0124] (3) Separation and drying

[0125] Solid-liquid separation: The mixed system after the modification reaction was transferred to a centrifuge tube and centrifuged for 15 min at 8000 r / min and 25℃ using a high-speed centrifuge to completely precipitate the Li6PS5Cl particles and separate and remove the supernatant containing unadsorbed 1,2-ethylenedithiol ethanol.

[0126] Vacuum drying: The solid precipitate obtained by centrifugation was transferred to a vacuum drying oven and dried at 60℃ and vacuum degree ≤ -0.09MPa for 4h; 1,2-ethylenedithiol modified Li6PS5Cl product was obtained, in which the D50 particle size of the core layer was 5.3μm and the thickness of the shell layer was 43nm.

[0127] Comparative Example 5:

[0128] Single PEO coating of Li3PS4

[0129] Pure PEO was coated onto the surface of Li3PS4 using a spray drying method, following the same steps as in Example 1, wherein the D50 particle size of the core layer was 3.5 μm and the thickness of the shell layer was 40 nm.

[0130] Comparative Example 6:

[0131] SiO2-coated Li 10 GeP2S 12

[0132] Chemical vapor deposition (CVD) was used in the Li 10 GeP2S 12 The surface is coated with SiO2, and the steps are as follows:

[0133] (1) Raw material preparation

[0134] Tetraethoxysilane (TEOS, analytical grade, purity ≥99%) was selected as the SiO2 precursor, oxygen (purity ≥99.99%) as the oxidizing gas, and argon as the carrier gas and dilution gas. TEOS was vaporized by heating in a constant temperature water bath (40℃), and the vaporized TEOS was mixed with oxygen and argon in a volume ratio of 1:5:10.

[0135] (2) Substrate pretreatment and placement

[0136] Weigh 10g of laboratory-made Li 10 GeP2S 12 The powder (average particle size 500 nm, purity ≥99.5%) was placed in a quartz boat and spread evenly. The quartz boat was placed in the constant temperature zone of the CVD reactor, the reactor was closed, and the vacuum was evacuated again to ≤-0.1 MPa. Argon gas was introduced (flow rate 50 mL / min) for 10 min, and the airtightness of the reactor was confirmed to be good (pressure change ≤0.01 MPa / 10 min).

[0137] (3) SiO2 deposition reaction

[0138] The temperature of the constant temperature zone of the reactor was raised to 150℃ at a heating rate of 5℃ / min. After the temperature stabilized, the TEOS vaporization device and oxygen valve were turned on, and the total flow rate of the mixed gas was adjusted to 100mL / min to start the SiO2 deposition reaction. The reaction time was 3h.

[0139] (4) Cooling and material handling

[0140] After the reaction was complete, the TEOS vaporization device was shut off, and oxygen and argon (volume ratio 1:10) were continuously introduced for 30 minutes to ensure that the unreacted TEOS was completely oxidized to SiO2. Then, oxygen was stopped, and only argon (flow rate 50 mL / min) was introduced to cool the reactor to room temperature at a cooling rate of 3 °C / min. The reactor was opened, the quartz boat was removed, and SiO2-coated Li was obtained. 10 GeP2S 12 The product has a core layer D50 particle size of 2.5 μm and a shell layer thickness of 324 nm.

[0141] To visually observe the beneficial effects of this invention, a unified testing method was adopted, specifically including:

[0142] (1) Hydrogen sulfide (H2S) release: Using a gas chromatograph, 0.5g of sample was placed in a closed environment at 25℃ and relative humidity of 40%~85% for 24h, and the concentration of released H2S was detected. The amount of H2S released per unit mass of sample was calculated.

[0143] (2) Ionic conductivity: The sample was pressed into a disc with a diameter of 10 mm and a thickness of 1 mm using an AC impedance meter. Au electrodes were wrapped on both sides and tested at 25 °C (frequency range 1 Hz ~ 1 MHz). The initial ionic conductivity and conductivity retention rate after 24 h were calculated.

[0144] (3) Mass change rate: The mass of the sample before and after placement was measured using a precision electronic balance, and the mass change rate was calculated (mass change rate = (mass after placement - initial mass) / initial mass × 100%).

[0145] (4) Interface impedance: The interface impedance between the sample and the lithium metal anode was tested using an AC impedance meter (test conditions were the same as for ionic conductivity).

[0146] (5) Battery performance: The sample was assembled with NCM811 positive electrode (active material content 90%, non-NCM811 positive electrode cases are marked in the table below) and lithium metal negative electrode into CR2032 all-solid-state battery. The first charge and discharge efficiency and capacity retention after 50 cycles were tested at 25°C at a 0.1C rate.

[0147] The test results are as follows:

[0148] Sample Name H2S release (mg / g) Initial ionic conductivity (S / cm) Ion conductivity retention rate (%) Quality change rate (%) Interfacial impedance with Li metal (Ω·cm²) First charge / discharge efficiency (%) Capacity retention rate after 50 cycles (%) Example 1 (PEO-SH / Li3PS4) 0.07 1.2 x 10 -3 ]]> 92.5 1.5 85 89 91 Example 2 (PVDF-SH / Li6PS5Cl) 0.05 <![CDATA[1.5×10 -3 ]]> 94.7 1.2 78 91 93 <![CDATA[Example 3 (PCL-SH / Li 10 GeP2S 12 )]]> 0.08 <![CDATA[2.1×10 -3 ]]> 90.2 1.8 92 92 (LFP positive electrode) 94 (LFP positive electrode) <![CDATA[Example 4 (PTFE-SH / Li9. 54 Si1. 74 P1. 44 S 11 .7Cl0.6)]]> 0.06 <![CDATA[1.8×10 -3 ]]> 93.3 1.4 82 90 (NCM622 positive electrode) 92 (NCM622 positive electrode) <![CDATA[Example 5 (PLA-SH / Li7P3S 11 )]]> 0.07 <![CDATA[1.6×10 -3 ]]> 91.8 1.6 88 89 (LCO positive electrode) 90 (LCO positive electrode) <![CDATA[Example 6 (PVDF-SH / Li6PS5Br)]]> 0.05 <![CDATA[1.4×10 -3 ]]> 93.9 1.3 80 90 92 <![CDATA[Example 7 (PEO-SH / Li 10 GeP2S 12 )]]> 0.07 <![CDATA[2.0×10 -3 ]]> 92.5 1.5 86 93 (LFP positive electrode) 95 (LFP positive electrode) <![CDATA[Comparative Example 1 (unmodified Li6PS5Cl)]]> 0.65 <![CDATA[1.4×10 -3 ]]> 40.0 5.8 220 75 68 <![CDATA[Comparative Example 2 (Al2O3 / Li3PS4)]]> 0.21 <![CDATA[1.0×10 -3 ]]> 73.0 3.2 180 82 79 <![CDATA[Comparative Example 3 (PVDF / Li6PS5Cl, without mercapto group)]]> 0.18 <![CDATA[1.3×10 -3 ]]> 78.0 2.5 150 85 83 <![CDATA[Comparative Example 4 (1,2-Ethanedithiol / Li6PS5Cl)]]> 0.25 <![CDATA[1.3×10 -3 ]]> 65.0 3.8 160 80 75 <![CDATA[Comparative Example 5 (PEO / Li3PS4, without mercapto group)]]> 0.22 <![CDATA[1.1×10 -3 ]]> 70.0 3.0 145 81 78 <![CDATA[Comparative Example 6 (SiO2 / Li 10 GeP2S 12 )]]> 0.30 <![CDATA[1.9×10 -3 ]]> 68.0 4.2 190 83 (LFP positive electrode) 76 (LFP positive electrode)

[0149] The following conclusions can be drawn from the comparison of the results in the table above:

[0150] (1) Environmental stability: The synergistic effect of the "thiol group + hydrophobic segment" in this invention is significantly better than that of the prior art;

[0151] The following can be clearly identified from the three core indicators: H2S release amount, ionic conductivity retention rate, and mass change rate:

[0152] The H2S release in Examples 1-7 was ≤0.08mg / g, which was much lower than that in Comparative Example 1 (0.65mg / g), Comparative Example 2 (0.21mg / g), and Comparative Example 4 (0.25mg / g). This indicates that the strong reducing property of thiol (-SH) can preferentially react with oxidizing substances in the air, thus preventing sulfides from reacting with water to generate H2S.

[0153] The ionic conductivity retention rates of the examples were all ≥90.2%, while those of Comparative Example 1 were only 40.0% and Comparative Example 6 were only 68.0%. This is because the hydrophobic segments (PVDF, PTFE, etc.) of the modified polymers of this invention form a dense physical barrier, reducing water and oxygen permeation. Simultaneously, the thiol groups interact with the Li groups on the sulfide surface. + P 5+ The coordination effect enhances the shell bonding strength and prevents the coating layer from falling off, which would cause a sharp drop in conductivity.

[0154] The mass change rate of the examples was ≤1.8%, which was much lower than that of Comparative Example 1 (5.8%) and Comparative Example 6 (4.2%), proving that the hydrophobic segments effectively suppressed the hygroscopic properties of sulfides. In contrast, existing technologies (such as SiO2 coating and small molecule modification) still have significant hygroscopic problems due to the lack of a continuous hydrophobic barrier.

[0155] (2) Interface performance: The coordination bonding and polymer flexibility of the present invention can improve the cycle stability of the battery;

[0156] From the interface impedance, initial charge / discharge efficiency, and cycle capacity retention, we can see that:

[0157] The interfacial impedance of the embodiments with Li metal is ≤92Ω·cm², which is only 42% of that of Comparative Example 1 (220Ω·cm²) and 48% of that of Comparative Example 6 (190Ω·cm²). This is because the coordination binding of thiol groups and sulfides reduces interfacial defects, while the flexible polymer chains adapt to changes in electrode volume and maintain interfacial contact.

[0158] The first charge-discharge efficiency of the embodiment is ≥89%, and the capacity retention rate after 50 cycles is ≥90%, while the first efficiency of Comparative Example 1 is only 75%, the cycle retention rate is only 68%, and the cycle retention rate of Comparative Example 3 (without thiol PVDF coating) is only 83%. This proves that thiol not only improves environmental stability, but also reduces interfacial charge transfer resistance, reduces interfacial side reactions, and extends battery life.

[0159] (3) The introduction of thiol groups is the key to achieving "active anti-oxidation + strong interfacial binding". The performance level of this invention cannot be achieved by simply hydrophobic coating (without thiol groups).

[0160] Single-variable comparisons were made between "Example 2 and Comparative Example 3" and "Example 1 and Comparative Example 5":

[0161] The H2S release of Example 2 (PVDF-SH) (0.05 mg / g) was only 27.8% of that of Comparative Example 3 (PVDF, 0.18 mg / g), and the conductivity retention rate (94.7%) was 21.4% higher than that of Comparative Example 3 (78.0%).

[0162] Interface impedance (85 Ω·cm) of Example 1 (PEO-SH) ² Comparative Example 5 (PEO, 145 Ω·cm) ² The rate of decrease was 41.4%, and the cycle retention rate (91%) was 16.7% higher than that of control group 5 (78%).

[0163] In summary, this invention, through a "core-shell" structure design, uses a thiol-containing modified polymer as the shell layer, combined with spray drying and solution coating methods, to achieve a synergistic improvement in the environmental stability and interfacial performance of sulfide solid electrolytes. This is significantly superior to unmodified and existing modification technologies, and has the potential for industrial application.

[0164] This invention has been described by way of embodiments, but does not constitute a limitation thereof. Other variations of the disclosed embodiments, which are readily apparent to those skilled in the art, should fall within the scope of the claims of this invention, with reference to the description of this invention.

Claims

1. A sulfide solid electrolyte material with excellent environmental stability, characterized in that: It includes a core layer (1) and a shell layer (2), wherein the shell layer (2) covers the core layer (1); The core layer (1) is mainly composed of a sulfide solid electrolyte matrix; The shell (2) is mainly composed of a modified polymer, which includes hydrophobic segments (21) and coordination functional groups (22), wherein the coordination functional groups (22) are only thiol groups; The composition of the core layer (1) and shell layer (2) has the following characteristics: After being placed in air with a relative humidity of 40%~85% and a temperature of 25℃ for 24 hours: hydrogen sulfide release ≤0.08mg / g; initial ionic conductivity ≥1×10 -3 Under the condition of S / cm, the ionic conductivity retention rate is ≥90%; the mass change rate is ≤2%.

2. The sulfide solid electrolyte material with excellent environmental stability according to claim 1, characterized in that: The hydrophobic segment (21) includes at least one of polyethylene oxide segment, polyvinylidene fluoride segment, polytetrafluoroethylene segment, polycaprolactone segment, or polylactic acid segment, which physically blocks water and oxygen permeation through hydrophobic interaction.

3. The sulfide solid electrolyte material with excellent environmental stability according to claim 1 or 2, characterized in that: The modified polymer is at least one of thiol-modified polyethylene oxide, thiol-modified polyvinylidene fluoride, thiol-modified polytetrafluoroethylene, thiol-modified polycaprolactone, or thiol-modified polylactic acid.

4. The sulfide solid electrolyte material with excellent environmental stability according to claim 1, characterized in that: The thickness of the shell (2) is 5 to 200 nm.

5. The sulfide solid electrolyte material with excellent environmental stability according to claim 4, characterized in that: The thickness of the shell (2) is 50-150 nm.

6. The sulfide solid electrolyte material with excellent environmental stability according to claim 1, characterized in that: The hydrogen sulfide release is ≤0.06 mg / g; the ionic conductivity retention rate is ≥93%; and the mass change rate is ≤1.5%.

7. The sulfide solid electrolyte material with excellent environmental stability according to claim 1, characterized in that: The sulfide solid electrolyte matrix includes Li3PS4 and Li7P3S. 11 Li 10 GeP2S 12 Li6PS5X (where X is Cl, Br, I, or F), or Li 9.54 Si 1.74 P 1.44 S 11.7 Cl 0.6 At least one of them.

8. The sulfide solid electrolyte material with excellent environmental stability according to claim 1, characterized in that: The average particle size of the core layer is 100 nm to 5 μm.

9. A preparation method according to any one of claims 1 to 8, characterized in that: Includes the following steps: S1. Preparation of the spray-drying precursor solution: Sulfide solid electrolyte powder, mercapto-containing modified polymer, and optional dispersant are added to an organic solvent and stirred at less than 500 r / min for 1 to 4 hours at 25℃ to 60℃. Then, the mixture is ultrasonically dispersed to obtain a uniformly dispersed, non-agglomerated spray-drying precursor liquid. The sulfide solid electrolyte powder is selected from Li3PS4 and Li7P3S. 11 Li 10 GeP2S 12 Li6PS5X (where X is Cl, Br, I, or F), or Li 9.54 Si 1.74 P 1.44 S 11.7 C 0.6 At least one of them, with an average particle size of 100 nm to 5 μm; The modified polymer is selected from at least one of thiol-modified polyethylene oxide, thiol-modified polyvinylidene fluoride, thiol-modified polytetrafluoroethylene, thiol-modified polycaprolactone, or thiol-modified polylactic acid. The dispersant is selected from polyvinylpyrrolidone, sodium dodecylbenzenesulfonate, polyethylene glycol, or triblock copolymer EO. 106 PO 70 EO 106 At least one of them; The organic solvent is selected from at least one of N,N-dimethylformamide, N-methylpyrrolidone, tetrahydrofuran, or dichloromethane to ensure that the modified polymer is completely dissolved and does not react with the sulfide solid electrolyte. The mass ratio of the sulfide solid electrolyte powder to the modified polymer is 5-20:1 to ensure that the shell thickness is controllable. The amount of dispersant added is 0.1-2% of the mass of the sulfide solid electrolyte powder to prevent sulfide particles from agglomerating. The liquid-solid content of the spray-drying precursor is 5wt%~20wt%, which balances atomization efficiency and coating uniformity. S2. Spray-dried coating: The spray drying precursor liquid obtained in step S1 is passed into a spray drying device and spray dried under inert gas protection to obtain the polymer-sulfide solid electrolyte composite primary product. During this process, the solvent in the tiny droplets evaporates rapidly, and the modified polymer is uniformly coated on the surface of the sulfide particles due to surface tension, forming a "core-shell" structure primary product. S3. Vacuum Post-treatment The polymer-sulfide solid electrolyte composite primary product obtained in step S2 is placed in a vacuum drying oven to remove residual solvent, thereby obtaining the target sulfide solid electrolyte material.

10. The preparation method according to claim 9, characterized in that: The atomizer of the spray drying equipment is a centrifugal atomizer with a rotation speed of 10,000 to 30,000 r / min or a centrifugal atomizer with an atomization pressure of 0.5 to 2 MPa, to ensure that the precursor liquid is atomized into tiny droplets of 5 to 50 μm. The inlet air temperature of the spray drying equipment is 80-150℃, which rapidly evaporates the solvent and avoids droplet aggregation; The outlet air temperature of the spray drying equipment is 40-80℃, which is lower than the decomposition temperature of the modified polymer, ensuring that the thiol groups are not destroyed; The feed rate of the spray drying equipment is 5~20mL / min, which matches the atomization and drying rates to avoid the adhesion of undried droplets.

11. The preparation method according to claim 9, characterized in that: The inert gas is argon or nitrogen, and the flow rate of the inert gas is 10-30 m³ / h.

12. The preparation method according to claim 9, characterized in that: The heating rate of the vacuum drying process is 2-5℃ / min to avoid excessively rapid heating that could cause the composite particles to crack.

13. A preparation method according to any one of claims 1 to 8, characterized in that: The steps include the following: S1. Preparation of modified polymer solution Select a modified polymer, add it to an organic solvent, and stir at 25℃~50℃ and a stirring rate of 200~400r / min for 2~3h until the modified polymer is completely dissolved and there are no visible particles in the solution, to obtain a modified polymer solution with a mass concentration of 0.5%~5%. The modified polymer is selected from at least one of thiol-modified polyethylene oxide, thiol-modified polyvinylidene fluoride, thiol-modified polytetrafluoroethylene, thiol-modified polycaprolactone, or thiol-modified polylactic acid. The organic solvent must meet the following conditions: it must be able to completely dissolve the modified polymer; it must not react chemically with the sulfide solid electrolyte; and its boiling point must be 60℃~150℃ to facilitate subsequent vacuum drying removal. S2. Directional adsorption and coating reaction The sulfide solid electrolyte powder is slowly added to the modified polymer solution obtained in step S1 at a mass ratio of sulfide solid electrolyte powder: modified polymer of 8~15:1, and the feeding rate is controlled at 0.5~2g / min to avoid excessive local concentration that may cause particle agglomeration. After the feed is completed, the mixture is transferred to a constant temperature water bath reactor and stirred at 25℃~50℃ and a stirring rate of 300~500r / min for 2~6h to ensure that the modified polymer has been completely adsorbed on the surface of the sulfide to obtain the coated intermediate. S3. Solid-liquid separation and purification The coated intermediate obtained in step S2 is transferred to a centrifuge tube and centrifuged for 10 to 15 minutes at a speed of 5000 to 8000 r / min and a temperature of 25℃ to 30℃ to completely precipitate the sulfide particles adsorbed with the modified polymer and separate and remove the clear liquid containing free polymer from the upper layer. Add the same organic solvent as in step S1 to the centrifuge tube, the amount of which is 1 / 3 to 1 / 2 of the initial polymer solution volume. Stir at 3000 to 5000 r / min for 5 to 10 min to wash. Then repeat the centrifugation operation. Wash in this way 2 to 3 times to obtain the purified solid product. S4. Vacuum drying and characterization The purified solid product obtained in step S3 was transferred to a vacuum drying oven and pre-dried for 2-4 hours at 60℃~80℃ and vacuum degree ≤-0.08MPa to remove most of the surface adsorbed solvent. Then, the temperature was raised to 80℃~100℃ and the vacuum degree was maintained at ≤-0.1MPa for 6-8 hours. After cooling to room temperature, the product was taken out to obtain a sulfide solid electrolyte material with a "core-shell" structure.

14. The preparation method according to claim 13, characterized in that: The organic solvent is at least one of N,N-dimethylformamide, N-methylpyrrolidone, or tetrahydrofuran.

15. The preparation method according to claim 13, characterized in that: In step S2, ultrasonic assistance is introduced during the stirring process. The ultrasonic power is 100~200W and the ultrasonic time is 30~60min. Ultrasonic stirring is performed alternately to disperse the micro-agglomerates by utilizing the ultrasonic cavitation effect.

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