Lithium sulfide powder for solid-state electrolyte and method for preparing the same

Abstract

The application discloses a lithium sulfide powder for solid electrolyte and a preparation method thereof, wherein the oxygen content in the lithium sulfide powder is less than or equal to 1% by weight, the halogen content is between 0.1 and 10% by weight, the total content of lithium, sulfur and halogen is greater than or equal to 98% by weight, and the BET specific surface area is between 1 and 20 m 2 / g. By adding ammonium halide in the preparation process of the lithium sulfide powder, the oxygen element in the lithium sulfide is converted into halogen, the content of the oxygen element in the lithium sulfide is greatly reduced, the specific surface area value of the lithium sulfide powder is improved, and the prepared solid electrolyte Li 6‑ x PS 5‑x X 1+x has a higher conversion rate, and the ionic conductivity performance is obviously superior to that of the Li 6‑x PS 5‑x X 1+x material synthesized by using conventional lithium sulfide.

Description

Technical Field

[0001] This invention relates to the field of lithium-ion battery technology, and in particular to a lithium sulfide powder for solid electrolyte and its preparation method. Background Technology

[0002] Inorganic sulfide solid electrolytes are due to their high lithium-ion conductivity (10). –4 —10 –2 S cm -1 Due to its good plasticity, it has attracted widespread attention and is considered one of the most promising solid electrolytes for use in assembling all-solid-state batteries. Lithium-sulfur silver-germanium mineral-type solid electrolyte Li 6-x PS 5-x X 1+x (X = Cl, Br, I) has 10 -3 S cm -1 The above ionic conductivity is comparable to that of commercially available liquid electrolytes. Among them, the Li-based... 6-x PS 5-x Cl 1+x All-solid-state batteries developed with solid-state electrolytes have entered the commercial testing phase.

[0003] Li 6-x PS 5-x Cl 1+x Solid electrolytes are synthesized from three raw materials: Li₂S, LiCl, and P₂S₅. Li₂S is used in the largest quantity and has the highest unit price. 6-x PS 5-x Cl 1+x Electrolyte cost is a significant component. To achieve optimal synthesis yield in the preparation of the aforementioned sulfide solid electrolyte, it is necessary to increase the reactivity of each raw material and to increase the specific surface area of ​​Li₂S. In addition to the required increased reactivity, Li₂S should be of high purity, preferably free of foreign elements or other impurities. The presence of impurities reduces the stability of the galvanic cell and results in low raw material conversion rates.

[0004] Li₂S exhibits strong hydrolytic properties; upon contact with even trace amounts of moisture in the environment, it releases H₂S gas and generates oxides. Currently, common methods for synthesizing Li₂S include reacting metallic Li and elemental S under high-temperature conditions or in an organic phase, reducing Li₂SO₄ at high temperatures, and reacting H₂S gas with lithium oxides. Regardless of the method used, the issue of high oxygen content needs to be addressed, as excessively high oxygen content in Li₂S results in low ionic conductivity of the synthesized sulfide electrolyte. Summary of the Invention

[0005] The purpose of this invention is to provide a lithium sulfide powder for solid electrolytes and its preparation method. By adding ammonium halide during the preparation of lithium sulfide powder, the oxygen element in lithium sulfide is converted into halogen, which greatly reduces the oxygen content in lithium sulfide and increases the specific surface area of ​​lithium sulfide powder. 6-x PS 5-x X 1+x It exhibits higher conversion rates and significantly better ionic conductivity than Li synthesized from conventional lithium sulfide. 6-x PS 5-x X 1+x Material.

[0006] To address the aforementioned technical problems, a first aspect of this invention provides a lithium sulfide powder for solid electrolytes, wherein the lithium sulfide powder has an oxygen content ≤1 wt%, a halogen content between 0.1 and 10 wt%, a total content of lithium, sulfur, and halogen elements ≥98 wt%, and a BET specific surface area between 1 and 20 m². 2 Between / g.

[0007] Furthermore, the oxygen content is ≤0.5% by weight.

[0008] Furthermore, the total content of lithium, sulfur, and halogen elements is ≥99% by weight.

[0009] Furthermore, the halogen includes one or more of the elements chlorine, bromine, and iodine.

[0010] Accordingly, a second aspect of the present invention provides a method for preparing lithium sulfide powder for solid electrolytes, comprising the following steps:

[0011] Lithium sulfate is reduced by mixing lithium source with sulfur source or by using a reducing agent, and then heated at a first preset temperature for a first preset time to obtain crude lithium sulfide with an oxygen content ≤ 5% by weight.

[0012] The crude lithium sulfide is mixed with ammonium halide, and an inert gas is introduced to keep it at a second preset temperature for a second preset time until the oxygen content is ≤1% by weight, thus obtaining the lithium sulfide powder.

[0013] Furthermore, the lithium source is lithium hydroxide or lithium carbonate;

[0014] The sulfur source is hydrogen sulfide gas or carbon disulfide.

[0015] Furthermore, the reducing agent is carbon powder, organic carbon, or hydrogen.

[0016] Furthermore, the ammonium halide is one or more of ammonium chloride, ammonium bromide, and ammonium iodide.

[0017] Furthermore, the numerical range of the first preset temperature is 250℃-1000℃;

[0018] The first preset duration ranges from 60 min to 600 min;

[0019] The second preset temperature ranges from 350℃ to 600℃;

[0020] The second preset duration ranges from 60 min to 600 min.

[0021] Furthermore, the range of the first preset temperature is 400℃-900℃;

[0022] The second preset temperature range is 400℃-550℃.

[0023] The above-described technical solutions of the embodiments of the present invention have the following beneficial technical effects:

[0024] By adding ammonium halide during the preparation of lithium sulfide powder, the oxygen element in lithium sulfide is converted into halogen, which greatly reduces the oxygen content in lithium sulfide and increases the specific surface area of ​​lithium sulfide powder. This is beneficial for the preparation of solid electrolytes such as Li. 6-x PS 5-x X 1+x It exhibits higher conversion rates and significantly better ionic conductivity than Li synthesized from conventional lithium sulfide. 6- x PS 5-x X 1+x Material. Attached Figure Description

[0025] Figure 1 This is a flowchart of the method for preparing lithium sulfide powder for solid electrolytes provided in this embodiment of the invention. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments and the accompanying drawings. It should be understood that these descriptions are merely exemplary and not intended to limit the scope of the invention. Furthermore, descriptions of well-known structures and techniques are omitted in the following description to avoid unnecessarily obscuring the concept of the invention.

[0027] A first aspect of this invention provides a lithium sulfide powder for solid electrolytes, wherein the lithium sulfide powder has an oxygen content ≤1 wt%, a halogen content between 0.1 and 10 wt%, a total content of lithium, sulfur, and halogen elements ≥98 wt%, and a BET specific surface area between 1 and 20 m². 2 Between / g.

[0028] This invention improves the quality of lithium sulfide raw materials by replacing oxygen in lithium sulfide with ammonium halide, thereby reducing the oxygen content in lithium sulfide powder. The resulting lithium sulfide powder has extremely low oxygen content and a high specific surface area, making it suitable for preparing solid electrolytes such as Li. 6-x PS 5-x X 1+x It exhibits high conversion rate, and its ionic conductivity is significantly superior to that of Li synthesized from conventional Li₂S. 6-x PS 5-x X 1+x Material.

[0029] BET specific surface area refers to the total area of ​​a unit mass of material.

[0030] Through component reactions, the oxygen element in lithium sulfide (Li₂S) is converted into halogens. Oxygen impurities in lithium sulfide (Li₂S) typically exist in three forms: lithium oxide (Li₂O), lithium hydroxide (LiOH), and lithium carbonate (Li₂CO₃). When oxygen-containing lithium sulfide (Li₂S) is mixed with ammonium halide and heated, the oxygen is released as water (H₂O) or carbon dioxide (CO₂). Simultaneously, the ammonium halide decomposes to generate large amounts of ammonium hydride (NH₃) gas and hydrogen halide (HX) gas, which then volatilize, increasing the specific surface area of ​​the hydrogen sulfide (Li₂S) powder. The relevant equations are as follows:

[0031] NH4X + Li2O → LiX + H2O + NH3;

[0032] NH4X + LiOH → LiX + H2O + NH3;

[0033] NH4X+Li2CO3→LiX+H2O+CO2+NH3;

[0034] NH4X→HX+NH3.

[0035] The product, lithium halide LiX, is a precursor to the synthesis of Li. 6-x PS 5-x X 1+x The above reaction can effectively convert harmful oxide impurities in lithium sulfide (Li2S) into usable lithium halide (LiX) as a raw material for sulfide solid electrolytes.

[0036] Furthermore, the oxygen content is ≤0.5% by weight; the total content of Li, S and halogen elements is ≥99% by weight.

[0037] Optionally, halogens include one or more of the elements chlorine, bromine, and iodine.

[0038] Based on the above, this invention provides a low-oxygen, chlorine-containing, high-specific-surface-area solid electrolyte lithium sulfide powder, with an oxygen content ≤1 wt%, a chlorine content between 0.1 and 10 wt%, a total content of Li, S, and halogen elements ≥98 wt%, and a BET specific surface area between 1 and 20 m². 2 / g.

[0039] A suitable specific surface area is crucial for ensuring the high reactivity of Li₂S powder in the synthesis of electrolytes. Specific surface area < 1 m² 2 The insufficient reactivity of Li₂S powder at a specific surface area of ​​20 m² / g will lead to poor performance of the synthesized electrolyte, while a specific surface area > 20 m² / g will result in poor performance of the synthesized electrolyte. 2 Powder of / g is difficult to obtain.

[0040] Accordingly, please refer to Figure 1 The second aspect of this invention provides a method for preparing lithium sulfide powder for solid electrolytes, comprising the following steps:

[0041] Step 1: Mix the lithium source with the sulfur source or reduce lithium sulfate with a reducing agent, and heat at a first preset temperature for a first preset time to obtain crude lithium sulfide with an oxygen content ≤ 5% by weight.

[0042] Step 2: Mix crude lithium sulfide with ammonium halide, introduce inert gas and keep warm at a second preset temperature for a second preset time until the oxygen content is ≤1% by weight to obtain lithium sulfide powder.

[0043] Specifically, in step 1, the lithium source is lithium hydroxide or lithium carbonate; the sulfur source is hydrogen sulfide gas or carbon disulfide.

[0044] Optionally, the reducing agent for reducing lithium sulfate in step 1 can be carbon powder or hydrogen.

[0045] Optionally, the ammonium halide is one or more of ammonium chloride, ammonium bromide, and ammonium iodide.

[0046] Optionally, the first preset temperature ranges from 250℃ to 1000℃, and preferably, the first preset temperature ranges from 400℃ to 900℃.

[0047] Optionally, the first preset duration can be in the range of 60 min to 600 min.

[0048] Optionally, the second preset temperature ranges from 350℃ to 600℃; preferably, the second preset temperature ranges from 400℃ to 550℃.

[0049] Optionally, the second preset duration can be in the range of 60 min to 600 min.

[0050] The method for preparing lithium sulfide powder in this technical solution will be described in detail below with reference to several embodiments:

[0051] Comparative Example 1: Commercially available Li2S sample A

[0052] Example 1: (1) 50g of anhydrous lithium hydroxide (LiOH) with a purity of 99.9% was placed in a graphite crucible in a glove box. The graphite crucible was placed in a quartz tube, sealed with a polytetrafluoroethylene stopper, and then removed from the glove box and transferred to a heating furnace. The temperature was raised and argon gas was introduced into the quartz tube at a flow rate of 2L / min. When the temperature reached 400℃, hydrogen sulfide (H2S) gas was introduced at a flow rate of 1L / min. After reacting for 60min, the heating was stopped and the hydrogen sulfide (H2S) gas was turned off. After cooling, the product was removed. (2) 10g of lithium sulfide (Li2S) with a high oxygen content obtained in the first step was ground and mixed evenly with a certain amount of ammonium chloride (NH4Cl) in an agate mortar in a glove box. The mixture was placed in a graphite crucible, placed in a quartz tube, sealed with a polytetrafluoroethylene stopper, and then removed from the glove box and transferred to a heating furnace. Argon gas was introduced into the quartz tube and the temperature was raised at a flow rate of 2 L / min. After holding at 400℃ for 120 min, the temperature was lowered and the product was removed after cooling to room temperature.

[0053] Example 2: (1) 50g of anhydrous lithium hydroxide (LiOH) with a purity of 99.9% was placed in a graphite crucible in a glove box. The graphite crucible was then placed in a quartz tube, sealed with a polytetrafluoroethylene stopper, and removed from the glove box and transferred to a heating furnace. Heating was started and argon gas was introduced into the quartz tube at a flow rate of 2L / min. When the temperature reached 250℃, hydrogen sulfide (H2S) gas was introduced at a flow rate of 1L / min. After reacting for 600min, heating was stopped and the hydrogen sulfide (H2S) gas was turned off. After cooling, the product was removed. (2) 10g of hydrogen sulfide (Li2S) with a high oxygen content obtained in the first step was ground and mixed evenly with a certain amount of ammonium bromide (NH4Br) in an agate mortar in a glove box.

[0054] The product was placed in a graphite crucible, which was then placed inside a quartz tube and sealed with a PTFE stopper. The product was then removed from the glove box and transferred to a heating furnace. Argon gas was introduced into the quartz tube and the temperature was raised at a flow rate of 2 L / min. The temperature was maintained at 350°C for 600 min, after which the temperature was lowered. The product was then removed after cooling to room temperature.

[0055] Example 3: (1) 50g of anhydrous lithium hydroxide (LiOH) with a purity of 99.9% was placed in a graphite crucible in a glove box. The graphite crucible was placed in a quartz tube, sealed with a polytetrafluoroethylene stopper, and then removed from the glove box and transferred to a heating furnace. The temperature was raised and argon gas was introduced into the quartz tube at a flow rate of 2L / min. When the temperature reached 500℃, hydrogen sulfide (H2S) gas was introduced at a flow rate of 1L / min. After reacting for 120min, the heating was stopped and the hydrogen sulfide (H2S) gas was turned off. After cooling, the product was removed. (2) 10g of the product with a high oxygen content obtained in step 1 and a certain amount of ammonium iodide (NH4I) were ground and mixed evenly in an agate mortar in a glove box. The graphite crucible was placed in a quartz tube, sealed with a polytetrafluoroethylene stopper, and then removed from the glove box and transferred to a heating furnace. Argon gas was introduced into the quartz tube and the temperature was raised at a flow rate of 2 L / min. After holding at 600℃ for 60 min, the temperature was lowered and the product was removed after cooling to room temperature.

[0056] Example 4: (1) 50g of anhydrous lithium carbonate (Li2CO3) with a purity of 99.9% was placed in a graphite crucible in a glove box. The graphite crucible was placed in a quartz tube, sealed with a polytetrafluoroethylene stopper, and then removed from the glove box and transferred to a heating furnace. The temperature was raised and argon gas was introduced into the quartz tube at a flow rate of 2L / min. When the temperature reached 650℃, hydrogen sulfide (H2S) gas was introduced at a flow rate of 1L / min. After reacting for 120min, the heating was stopped and the hydrogen sulfide (H2S) gas was turned off. After cooling, the product was removed. (2) 10g of lithium sulfide (Li2S) with a high oxygen content obtained in the first step was ground and mixed evenly with a certain amount of ammonium chloride (NH4Cl) in an agate mortar in a glove box. The mixture was placed in a graphite crucible, placed in a quartz tube, sealed with a polytetrafluoroethylene stopper, and then removed from the glove box and transferred to a heating furnace. Argon gas was introduced into the quartz tube and the temperature was raised at a flow rate of 2 L / min. After holding at 450℃ for 120 min, the temperature was lowered and the product was removed after cooling to room temperature.

[0057] Example 5: (1) 50g of anhydrous lithium sulfate (Li2SO4) with a purity of 99.9% was placed in a graphite crucible in a glove box, and the graphite crucible was placed in an atmosphere furnace. The temperature was raised and hydrogen gas was introduced into the quartz tube at a flow rate of 2L / min. The temperature was maintained at 900℃ for 120min, and the product was removed after cooling. (2) 10g of lithium sulfide (Li2S) with a high oxygen content obtained in the first step was ground and mixed evenly with a certain amount of ammonium chloride (NH4Cl) in an agate mortar in a glove box, and the mixture was placed in a graphite crucible. The graphite crucible was placed in a quartz tube, sealed with a polytetrafluoroethylene stopper, and then removed from the glove box and transferred to a heating furnace. Argon gas was introduced into the quartz tube and the temperature was raised at a flow rate of 2L / min. The temperature was maintained at 500℃ for 120min, and then the temperature was lowered. The product was removed after cooling to room temperature.

[0058] Example 6: (1) 50g of anhydrous lithium sulfate (Li2SO4) with a purity of 99.9% was mixed with 10.9g of carbon powder and placed in a graphite crucible. The graphite crucible was placed in an atmosphere furnace. Heating was started and argon gas was introduced at a flow rate of 2L / min. The temperature was gradually increased to 1000℃, and the product was removed after cooling. (2) In a glove box, 10g of lithium sulfide (Li2S) with a high oxygen content obtained in the first step was ground and mixed evenly with a certain amount of ammonium chloride (NH4Cl) in an agate mortar. The mixture was placed in a graphite crucible, which was then placed in a quartz tube, sealed with a polytetrafluoroethylene stopper, and removed from the glove box and transferred to a heating furnace. Argon gas was introduced into the quartz tube and the temperature was started at a flow rate of 2L / min. The temperature was maintained at 550℃ for 120min, and then the temperature was lowered. The product was removed after cooling to room temperature.

[0059] Table 1 Characteristics of Li2S powder

[0060]

[0061] By comparing Examples 1-6 in Table 1 with Comparative Example 1, it can be seen that the BET specific surface area of ​​the lithium sulfide powder with added halogens is significantly increased, while the oxygen content is greatly reduced.

[0062] The following will focus on specific sulfide solid electrolytes, Li 5.5 PS 4.5 Cl 1.5 The embodiments further illustrate the beneficial effects of the present invention.

[0063] Comparative Example 2: 1.0 g of lithium sulfide (Li₂S) (commercial comparative sample A), 1.21 g of phosphorus pentasulfide, and 0.69 g of lithium chloride (LiCl) were accurately weighed in an argon-filled glove box. After thorough grinding and mixing, the mixture was placed into a 10 mm diameter quartz crucible. The crucible was then removed from the glove box and immediately connected to a vacuum system for evacuation. When the vacuum level reached 1 × 10⁻⁶... -3 The crucible was melted and sealed at Pa, and then placed in a tube furnace for heating and synthesis. The final sulfide electrolyte was obtained after high-temperature treatment at 500℃ for 15 hours, with a heating and cooling rate of approximately 3℃ / min.

[0064] Example 7: In an argon-filled glove box, according to Li 5.5 PS 4.5 Cl 1.5 The elemental composition of the material was determined by accurately weighing 1.09 g of lithium sulfide Li₂S (the lithium sulfide Li₂S sample obtained in Example 1 of this invention, with a chlorine content of 7% by weight), 1.21 g of phosphorus pentasulfide P₂S₅, and 0.60 g of lithium chloride LiCl. After thorough grinding and mixing, the mixture was placed into a 10 mm diameter quartz crucible. The quartz crucible was then removed from the glove box and quickly connected to a vacuum system for evacuation. When the vacuum level reached 1 × 10⁻⁶, the mixture was evacuated. -3The crucible was melted and sealed at Pa, and then placed in a tube furnace for heating and synthesis. The final sulfide electrolyte was obtained after high-temperature treatment at 500℃ for 15 hours, with a heating and cooling rate of approximately 3℃ / min.

[0065] Example 8: In an argon-filled glove box, according to Li 5.5 PS 4.5 Cl 1.5 The elemental composition of the materials was as follows: 1.12g of lithium sulfide Li₂S (the lithium sulfide Li₂S sample obtained in Example 4 of this invention, with a chlorine content of 9% by weight), 1.21g of phosphorus pentasulfide P₂S₅, and 0.57g of lithium chloride LiCl were accurately weighed, thoroughly ground and mixed, and then placed into a quartz crucible with a diameter of 10mm. All other operations were the same as in Example 7.

[0066] Example 9: In an argon-filled glove box, according to Li 5.5 PS 4.5 Cl 1.5 The elemental composition of the materials was as follows: 1.02 g of lithium sulfide Li₂S (the lithium sulfide Li₂S sample obtained in Example 5 of this invention, with a chlorine content of 1.5% by weight), 1.21 g of phosphorus pentasulfide P₂S₅, and 0.67 g of lithium chloride LiCl were accurately weighed, thoroughly ground and mixed, and then placed into a quartz crucible with a diameter of 10 mm. All other operations were the same as in Example 7 and Comparative Example 3.

[0067] Example 10: In an argon-filled glove box, according to Li 5.5 PS 4.5 Cl 1.5 The elemental composition of the materials was as follows: 1.05 g of lithium sulfide Li₂S (the lithium sulfide Li₂S sample obtained in Example 6 of this invention, with a chlorine content of 4% by weight), 1.21 g of phosphorus pentasulfide P₂S₅, and 0.64 g of lithium chloride LiCl were accurately weighed, thoroughly ground and mixed, and then placed into a quartz crucible with a diameter of 10 mm. The remaining operations were the same as in Example 7.

[0068] Table 2 Performance of Sulfated Solid Electrolytes

[0069]

[0070]

[0071] As shown in Table 2, the ionic conductivity of Examples 7-10 is significantly improved compared to Comparative Example 2.

[0072] This invention aims to protect a lithium sulfide powder for solid electrolytes and its preparation method, wherein the lithium sulfide powder has an oxygen content ≤1% by weight, a halogen content between 0.1% and 10% by weight, a total content of Li, S, and halogen elements ≥98% by weight, and a BET specific surface area between 1 and 20 m². 2Between / g. The above technical solution has the following effects:

[0073] By adding ammonium halide during the preparation of lithium sulfide powder, the oxygen element in lithium sulfide is converted into halogen, which greatly reduces the oxygen content in lithium sulfide and increases the specific surface area of ​​lithium sulfide powder. This is beneficial for the preparation of solid electrolytes such as Li. 6-x PS 5-x X 1+x It exhibits higher conversion rates and significantly better ionic conductivity than Li synthesized from conventional lithium sulfide. 6- x PS 5-x X 1+x Material.

[0074] It should be understood that the specific embodiments described above are merely illustrative or explanatory of the principles of the invention and do not constitute a limitation thereof. Therefore, any modifications, equivalent substitutions, improvements, etc., made without departing from the spirit and scope of the invention should be included within the protection scope of the invention. Furthermore, the appended claims are intended to cover all variations and modifications falling within the scope and boundaries of the appended claims, or equivalent forms of such scope and boundaries.

Claims

1. A lithium sulfide powder for solid electrolytes, characterized in that, The lithium sulfide powder contains ≤1% oxygen by weight, 0.1-10% halogen by weight, ≥98% total lithium, sulfur, and halogen content, and has a BET specific surface area between 1 and 20 m². 2 Between / g.

2. The lithium sulfide powder for solid electrolytes according to claim 1, characterized in that, The oxygen content is ≤0.5% by weight.

3. The lithium sulfide powder for solid electrolytes according to claim 1, characterized in that, The total content of lithium, sulfur and halogen elements is ≥99% by weight.

4. The lithium sulfide powder for solid electrolytes according to claim 1, characterized in that, The halogens include one or more of the elements chlorine, bromine, and iodine.

5. A method for preparing lithium sulfide powder for solid electrolytes, characterized in that, The method for preparing the lithium sulfide powder as described in any one of claims 1-4 comprises the following steps: Lithium sulfate crude product with oxygen content ≤ 5% by weight is obtained by mixing lithium source with sulfur source or reducing lithium sulfate with reducing agent and holding at a first preset temperature for a first preset time. The crude lithium sulfide is mixed with ammonium halide, and inert gas is introduced to keep it at a second preset temperature for a second preset time until the oxygen content is ≤1% by weight, thus obtaining the lithium sulfide powder.

6. The method for preparing lithium sulfide powder for solid electrolytes according to claim 5, characterized in that, The lithium source is lithium hydroxide or lithium carbonate; the sulfur source is hydrogen sulfide gas or carbon disulfide.

7. The method for preparing lithium sulfide powder for solid electrolytes according to claim 5, characterized in that, The reducing agent is carbon powder, organic carbon, or hydrogen.

8. The method for preparing lithium sulfide powder for solid electrolytes according to claim 5, characterized in that, The ammonium halide is one or more of ammonium chloride, ammonium bromide, and ammonium iodide.

9. The method for preparing lithium sulfide powder for solid electrolytes according to any one of claims 5-8, characterized in that, The first preset temperature ranges from 250℃ to 1000℃; the first preset duration ranges from 60min to 600min; the second preset temperature ranges from 350℃ to 600℃; and the second preset duration ranges from 60min to 600min.

10. The method for preparing lithium sulfide powder for solid electrolytes according to claim 9, characterized in that, The first preset temperature range is 400℃-900℃; the second preset temperature range is 400℃-550℃.

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