Sulfide solid electrolyte and preparation method thereof

Abstract

The invention relates to the technical field of electrode materials, in particular to a sulfide solid electrolyte and a preparation method thereof, and the preparation method is characterized by comprising the following steps: (1) selecting a lithium source and at least three of a sulfur source, a phosphorus source, elemental sulfur and a halogen source as raw materials, and mixing; the lithium source comprises at least one of lithium carbonate, lithium sulfate, lithium oxide, lithium hydroxide, lithium thiosulfate and lithium sulfite; and (2) putting the mixture prepared in the step (1) into a sintering furnace under the protection of inert gas, and introducing reducing gas for sintering treatment to obtain the sulfide electrolyte. The sulfide solid electrolyte provided by the invention adopts the lithium salt of non-lithium sulfide as the lithium source, the sulfide electrolyte is prepared by a one-step method, an intermediate lithium sulfide preparation link is omitted, and the sulfide solid electrolyte has the characteristics of low cost, simple process, batch industrial production and the like.

Description

Technical Field

[0001] The present application relates to the technical field of electrode materials, and in particular to a sulfide solid electrolyte and a preparation method thereof. Background Art

[0002] Sulfide solid electrolytes are a type of electrolyte material used in solid-state batteries, mainly composed of sulfides. Sulfide solid electrolytes can replace liquid electrolytes in traditional batteries and effectively improve battery safety and energy density.

[0003] The existing synthesis methods of sulfide solid electrolytes mainly include solid-phase ball milling and liquid-phase methods. Among them, the solid-phase ball milling method refers to directly grinding lithium sulfide and other raw materials in a ball mill, using the rotation and collision between the ball mill and the ball mill, and using mechanical stress to make the raw materials fully react, thereby obtaining a sulfide solid electrolyte. For example, patent CN11834699A provides a method for preparing argentum-germanium sulfide electrolytes, which uses lithium sulfide as a lithium source, uses a powder mill to crush and mix the raw materials, and performs sintering treatment to obtain argentum-germanium sulfide electrolytes. This method needs to be carried out under the condition that the water oxygen content is less than 5ppm, and the reaction requirements are strict, which seriously affects the promotion of mass production of sulfide electrolytes.

[0004] In addition to the problems of the process itself, the expensive lithium sulfide is also the reason that limits the widespread application of sulfide electrolyte materials. The main methods for synthesizing lithium sulfide include mechanical ball milling, solvent reaction, high temperature and high pressure, etc. Among them, the method of preparing lithium sulfide by reducing lithium salt with carbon has attracted widespread attention due to its low raw material cost and no pollution. However, due to the residual carbon in this scheme, the material needs to be washed with solvent to obtain high-purity lithium sulfide, making it still expensive. Summary of the invention

[0005] The purpose of the present application is to provide a sulfide solid electrolyte and a preparation method thereof. The sulfide solid electrolyte adopts a lithium salt other than lithium sulfide as a lithium source, and prepares the sulfide electrolyte by a one-step method, thereby eliminating the intermediate lithium sulfide preparation step. The sulfide electrolyte has the characteristics of low cost, simple process, and mass industrial production. The ionic conductivity of the prepared sulfide electrolyte material can be as high as 7 mS / cm.

[0006] In a first aspect, the present application provides a method for preparing a sulfide solid electrolyte, characterized in that it comprises the following steps: (1) selecting a lithium source and at least three of a sulfur source, a phosphorus source, elemental sulfur, and a halogen source as raw materials and mixing them; the lithium source comprises at least one of lithium carbonate, lithium sulfate, lithium oxide, lithium hydroxide, lithium thiosulfate, and lithium sulfite; (2) placing the mixture obtained in step (1) in a sintering furnace under the protection of an inert gas, introducing a reducing gas for sintering, and obtaining the sulfide electrolyte.

[0007] The present invention is a one-step method for preparing a sulfide solid electrolyte. Compared with the traditional method of preparing a sulfide electrolyte using lithium sulfide, the lithium source used in this aspect is relatively cheap and has a significant cost advantage. The present invention mixes the raw materials and introduces a reducing gas for sintering treatment, so that the lithium source used is converted into lithium sulfide during the sintering process, and reacts with other raw materials to obtain the sulfide electrolyte. There is no need to purify the lithium sulfide, the process flow is simple, and it is suitable for industrial large-scale preparation of sulfide electrolytes.

[0008] In some embodiments, in step (1), the sulfur source includes at least one of germanium sulfide, silicon sulfide, selenium sulfide, arsenic sulfide, iron sulfide, cobalt sulfide, nickel sulfide, and copper sulfide.

[0009] The present invention uses the above sulfides as sulfur sources to prepare sulfide electrolytes, which can simplify the synthesis process because they do not need to go through an additional sulfurization step and can directly react with a lithium source to generate lithium sulfide or other desired sulfide electrolytes. In addition, certain elements in these sulfides (such as germanium, silicon, and selenium) help to form a sulfide network structure with good ionic conductivity. Among them, germanium sulfide and silicon sulfide have high chemical stability, which helps to improve the stability of the sulfide electrolyte under battery working conditions.

[0010] In some embodiments, in step (1), the phosphorus source includes at least one of phosphorus pentasulfide, phosphorus trisulfide, tetraphosphorus nonasulfide, tetraphosphorus trisulfide, tetraphosphorus hexasulfide, tetraphosphorus pentasulfide, red phosphorus, and white phosphorus.

[0011] In the embodiment, phosphosulfide is used as the phosphorus source, which can not only provide phosphorus ions but also directly provide sulfur elements, thereby reducing the amount of sulfur source added and saving costs.

[0012] In some embodiments, in step (1), the halogen source is at least one of lithium chloride, lithium bromide, lithium iodide, and lithium fluoride.

[0013] In the embodiment, lithium halide is used as the halogen source, which can not only provide halogen ions to form a structure conducive to ion conduction with other components in the sulfide electrolyte, but also directly provide lithium ions, thereby reducing the amount of lithium source added and saving costs.

[0014] In some embodiments, the mixing in step (1) includes crushing and mixing the raw materials using a ball mill or a roller mill.

[0015] In the embodiment, the raw materials are crushed and mixed by ball mill or roller mill, so that the raw materials can be fully mixed, which is helpful for the reaction in the subsequent sintering process.

[0016] In some embodiments, in step (1), when elemental sulfur is selected, the amount of elemental sulfur added is 0.5-5% of the total mass of the raw materials excluding elemental sulfur.

[0017] In the embodiments, in order to supplement the sulfur volatilization existing in the sintering process and reduce sulfur defects, elemental sulfur is selected as the raw material, and the sulfur content of the sulfide electrolyte is precisely controlled. In addition, elemental sulfur has a high reactivity and can react quickly with a lithium source or lithium halide to improve the synthesis efficiency, which is conducive to the preparation of high-performance sulfide electrolytes.

[0018] In some embodiments, in the step (2), the sintering treatment specifically includes: placing the mixture in a sintering furnace under the protection of an inert gas, introducing a reducing gas for heating, and obtaining the sulfide electrolyte.

[0019] In some embodiments, the sintering process specifically includes three stages. The first stage maintains the temperature at 160-325 degrees Celsius and the insulation time is 60-120 minutes. The second stage maintains the temperature at 500-700 degrees Celsius and the insulation time is 30-60 minutes. The third stage maintains the temperature at 450-650 degrees Celsius and the insulation time is 240-480 minutes. The reducing gas is introduced when and only when it is in the second stage of heating.

[0020] In the embodiment, the sintering process is divided into three stages: Stage 1 (activation process): In this stage, low-temperature heating at 160-325 degrees Celsius helps activate the raw materials, causing some components in the raw materials to undergo preliminary physical or chemical changes in preparation for subsequent high-temperature reactions. For example, some compounds may decompose and release active lithium and sulfur elements.

[0021] The second stage (reduction process): In this stage, under high temperature conditions of 500-700 degrees Celsius, reducing gases (such as hydrogen, methane, etc.) react with the lithium source to reduce the lithium element in the lithium source to active lithium. At the same time, the sulfur source and elemental sulfur may also react to form lithium sulfide.

[0022] Stage 3 (material crystallization process): In the third stage, the temperature is reduced to 450-650 degrees Celsius to gradually cool the material. During this process, lithium sulfide and other generated compounds begin to crystallize to form a sulfide electrolyte with good ionic conductivity. The longer insulation time helps crystal growth and improves the structural and performance stability of the electrolyte.

[0023] The present invention can ultimately obtain a sulfide electrolyte with excellent performance through precise control of these three stages, and is suitable for electrochemical energy storage devices such as lithium-sulfur batteries.

[0024] In some embodiments, the reducing gas is at least one of methane, ethylene, acetylene, hydrogen sulfide, carbon disulfide, carbon monoxide, hydrogen, and sulfur monoxide, and the inert gas is nitrogen or argon.

[0025] In some embodiments, the rotation speed of the sintering furnace is 0.5-5 m / min.

[0026] In a second aspect, the present application provides a sulfide solid electrolyte, characterized in that the sulfide solid electrolyte is prepared by the preparation method described in any one of the first aspects.

[0027] The beneficial effects of a sulfide solid electrolyte and a preparation method thereof provided by the present invention include but are not limited to the following: (1) The present invention uses non-lithium sulfide lithium salt as a lithium source and prepares a sulfide electrolyte by a one-step method, thereby eliminating the intermediate step of preparing lithium sulfide. It has the characteristics of low cost, simple process, and mass industrial production. The ionic conductivity of the prepared sulfide electrolyte material can be as high as 7 mS / cm.

[0028] (2) The present invention adopts a one-step method to prepare a sulfide solid electrolyte. Compared with the traditional method of using lithium sulfide to prepare a sulfide electrolyte, the lithium source used in this aspect is relatively cheap and has a significant cost advantage. The present invention mixes the raw materials and introduces a reducing gas for sintering treatment, so that the lithium source used is converted into lithium sulfide during the sintering process, and reacts with other raw materials to prepare the sulfide electrolyte. There is no need to purify the lithium sulfide, the process flow is simple, and it is suitable for industrial large-scale preparation of sulfide electrolytes.

[0029] The present invention uses sulfide as a sulfur source to prepare a sulfide electrolyte, which can simplify the synthesis process because the sulfide does not need to undergo an additional sulfurization step and can directly react with a lithium source to generate lithium sulfide or other desired sulfide electrolytes. In addition, certain elements in these sulfides (such as germanium, silicon, and selenium) help to form a sulfide network structure with good ionic conductivity. Among them, germanium sulfide and silicon sulfide have high chemical stability, which helps to improve the stability of the sulfide electrolyte under battery working conditions.

[0030] (4) The present invention uses lithium halide as a halogen source, which can not only provide halogen ions to form a structure that is conducive to ion conduction with other components in the sulfide electrolyte, but also directly provide lithium ions, thereby reducing the amount of lithium source added and saving costs. DETAILED DESCRIPTION

[0031] The following description provides specific application scenarios and requirements of the present application, with the purpose of enabling those skilled in the art to make and use the content in the present application. It will be apparent to those skilled in the art that various local modifications to the disclosed embodiments are apparent, and the general principles defined herein may be applied to other embodiments and applications without departing from the spirit and scope of the present application. Therefore, the present application is not limited to the embodiments shown, but to the widest scope consistent with the claims.

[0032] The present application provides a method for preparing a sulfide solid electrolyte, characterized in that it comprises the following steps: (1) selecting a lithium source and at least three of a sulfur source, a phosphorus source, elemental sulfur, and a halogen source as raw materials and mixing them; the lithium source comprises at least one of lithium carbonate, lithium sulfate, lithium oxide, lithium hydroxide, lithium thiosulfate, and lithium sulfite; (2) placing the mixture obtained in step (1) in a sintering furnace under the protection of an inert gas, introducing a reducing gas for sintering, and obtaining the sulfide electrolyte.

[0033] The present invention is a one-step method for preparing a sulfide solid electrolyte. Compared with the traditional method of preparing a sulfide electrolyte using lithium sulfide, the lithium source used in this aspect is relatively cheap and has a significant cost advantage. The present invention mixes the raw materials and introduces a reducing gas for sintering treatment, so that the lithium source used is converted into lithium sulfide during the sintering process, and reacts with other raw materials to obtain the sulfide electrolyte. There is no need to purify the lithium sulfide, the process flow is simple, and it is suitable for industrial large-scale preparation of sulfide electrolytes.

[0034] A sulfide solid electrolyte and a preparation method thereof provided in the present application will be described in detail below in conjunction with specific embodiments.

[0035] The present application provides a method for preparing a sulfide solid electrolyte, characterized in that it comprises the following steps: (1) selecting a lithium source and at least three of a sulfur source, a phosphorus source, elemental sulfur, and a halogen source as raw materials and mixing them; the lithium source comprises at least one of lithium carbonate, lithium sulfate, lithium oxide, lithium hydroxide, lithium thiosulfate, and lithium sulfite; (2) placing the mixture obtained in step (1) in a sintering furnace under the protection of an inert gas, introducing a reducing gas for sintering, and obtaining the sulfide electrolyte.

[0036] In some embodiments, in step (1), the sulfur source includes at least one of germanium sulfide, silicon sulfide, selenium sulfide, arsenic sulfide, iron sulfide, cobalt sulfide, nickel sulfide, and copper sulfide.

[0037] In some embodiments, in step (1), the phosphorus source includes at least one of phosphorus pentasulfide, phosphorus trisulfide, tetraphosphorus nonasulfide, tetraphosphorus trisulfide, tetraphosphorus hexasulfide, tetraphosphorus pentasulfide, red phosphorus, and white phosphorus.

[0038] In the embodiment, phosphosulfide is used as the phosphorus source, which can not only provide phosphorus ions but also directly provide sulfur elements, thereby reducing the amount of sulfur source added and saving costs.

[0039] In some embodiments, in step (1), the halogen source is at least one of lithium chloride, lithium bromide, lithium iodide, and lithium fluoride.

[0040] In the embodiment, lithium halide is used as the halogen source, which can not only provide halogen ions to form a structure conducive to ion conduction with other components in the sulfide electrolyte, but also directly provide lithium ions, thereby reducing the amount of lithium source added and saving costs.

[0041] In some embodiments, the mixing in step (1) includes crushing and mixing the raw materials using a ball mill or a roller mill.

[0042] In the embodiment, the raw materials are crushed and mixed by ball mill or roller mill, so that the raw materials can be fully mixed, which is helpful for the reaction in the subsequent sintering process.

[0043] In some embodiments, in step (1), when elemental sulfur is selected, the amount of elemental sulfur added is 0.5-5% of the total mass of the raw materials excluding elemental sulfur, for example 0.5%, 1%, 2%, 3%, 4% or 5%.

[0044] In some embodiments, in the step (2), the sintering treatment specifically includes: placing the mixture in a sintering furnace under the protection of an inert gas, introducing a reducing gas for heating, and obtaining the sulfide electrolyte.

[0045] In some embodiments, the sintering process specifically includes three stages. The first stage is maintained at a temperature of 160-325 degrees Celsius, such as 160 degrees Celsius, 180 degrees Celsius, 200 degrees Celsius, 230 degrees Celsius, 260 degrees Celsius, 280 degrees Celsius, 300 degrees Celsius or 325 degrees Celsius, and the holding time is 60-120 minutes, such as 60 minutes, 80 minutes, 100 minutes or 120 minutes; the second stage is maintained at a temperature of 500-700 degrees Celsius, such as 500 degrees Celsius, 520 degrees Celsius, 550 degrees Celsius, 580 degrees Celsius, 600 degrees Celsius, 650 degrees Celsius, etc. Celsius, 680 degrees Celsius or 700 degrees Celsius, and the holding time is 30-60 min, such as 30 min, 40 min, 50 min or 60 min; the third stage maintains the temperature at 450-650 degrees Celsius, such as 450 degrees Celsius, 500 degrees Celsius, 550 degrees Celsius, 580 degrees Celsius, 600 degrees Celsius or 650 degrees Celsius, and the holding time is 240-480 min, such as 240 min, 300 min, 360 min, 400 min, 450 min or 480 min; when and only when in the second stage of heating, the reducing gas is introduced.

[0046] In some embodiments, the reducing gas is at least one of methane, ethylene, acetylene, hydrogen sulfide, carbon disulfide, carbon monoxide, hydrogen, and sulfur monoxide, and the inert gas is nitrogen or argon.

[0047] In some embodiments, the rotation speed of the sintering furnace is 0.5-5 m / min. Example 1

[0048] This embodiment provides a method for preparing a sulfide solid electrolyte, and the specific steps are as follows: lithium sulfate, lithium chloride, and phosphorus pentasulfide are mixed according to a stoichiometric ratio (the target product Li 6 PS 5 Cl) is weighed, and then 1wt% of elemental sulfur is added to crush and mix; the mixture is transferred to a rotary sintering furnace protected by inert gas, the speed of the rotary furnace is 1m / min, the first stage heat treatment temperature is 250℃, the holding time is 90min, the second stage temperature is 550℃, the holding time is 40min, the reducing gas passed is hydrogen sulfide gas, the third stage temperature is 450℃, the holding time is 300min, and the sulfide electrolyte is obtained after the heat treatment. Comparative Example 1

[0049] Lithium sulfide, lithium chloride and phosphorus pentasulfide were mixed in a stoichiometric ratio (the target product Li 6 PS 5Cl), weighed, crushed and mixed, and sintered in a rotary furnace with a rotary furnace speed of 1m / min, a sintering temperature of 450°C, and a sintering time of 300min. Example 2

[0050] This embodiment provides a method for preparing a sulfide solid electrolyte, and the specific steps are as follows: lithium carbonate, lithium chloride, and phosphorus pentasulfide are mixed according to a stoichiometric ratio (the target product Li 6 PS 5 Cl) is weighed, and then 1wt% of elemental sulfur is added to crush and mix; the mixture is transferred to a rotary sintering furnace protected by inert gas, the speed of the rotary furnace is 1m / min, the first stage heat treatment temperature is 250℃, the holding time is 90min, the second stage temperature is 550℃, the holding time is 40min, the reducing gas passed is hydrogen sulfide gas, the third stage temperature is 450℃, the holding time is 300min, and the sulfide electrolyte is obtained after the heat treatment. Example 3

[0051] This embodiment provides a method for preparing a sulfide solid electrolyte, and the specific steps are as follows: lithium thiosulfate, germanium sulfide, and phosphorus pentasulfide are mixed according to a stoichiometric ratio (the target product Li 10 G 2 S 12 ) is weighed, and then 1wt% of elemental sulfur is added for crushing and mixing; the mixture is transferred to a rotary sintering furnace protected by inert gas, the speed of the rotary furnace is 1m / min, the first stage heat treatment temperature is 250℃, the holding time is 90min, the second stage temperature is 550℃, the holding time is 40min, the reducing gas passed is hydrogen sulfide gas, the third stage temperature is 450℃, the holding time is 300min, and the sulfide electrolyte is obtained after the heat treatment. Example 4

[0052] This embodiment provides a method for preparing a sulfide solid electrolyte, and the specific steps are as follows: lithium sulfate, germanium sulfide, and phosphorus pentasulfide are mixed according to a stoichiometric ratio (the target product Li 10 G 2 S 12 ) is weighed, and then 2wt% of elemental sulfur is added for crushing and mixing; the mixture is transferred to a rotary sintering furnace protected by inert gas, the speed of the rotary furnace is 1m / min, the first stage heat treatment temperature is 250℃, the holding time is 90min, the second stage temperature is 650℃, the holding time is 60min, the reducing gas passed is hydrogen sulfide gas, the third stage temperature is 450℃, the holding time is 300min, and the sulfide electrolyte is obtained after the heat treatment. Comparative Example 2

[0053] Lithium sulfide, germanium sulfide, and phosphorus pentasulfide were mixed in a stoichiometric ratio (the target product Li 10 G 2 S 12 ) are weighed and crushed and mixed; the mixture is transferred to a rotary sintering furnace protected by inert gas, the rotation speed of the rotary furnace is 1m / min, the sintering temperature is 600 degrees Celsius, the sintering time is 360min, and the sulfide electrolyte is obtained after cooling. Example 5

[0054] This embodiment provides a method for preparing a sulfide solid electrolyte, and the specific steps are as follows: lithium sulfate, lithium chloride, and phosphorus pentasulfide are mixed according to a stoichiometric ratio (the target product Li 6 PS 5 Cl) is weighed, and then 1wt% of elemental sulfur is added to crush and mix; the mixture is transferred to a rotary sintering furnace protected by inert gas, the speed of the rotary furnace is 2m / min, the first stage heat treatment temperature is 250℃, the holding time is 90min, the second stage temperature is 550℃, the holding time is 40min, the reducing gas passed is carbon disulfide gas, the third stage temperature is 450℃, the holding time is 300min, and the sulfide electrolyte is obtained after the heat treatment. Example 6

[0055] This embodiment provides a method for preparing a sulfide solid electrolyte, and the specific steps are as follows: lithium sulfate, lithium chloride, and phosphorus pentasulfide are mixed according to a stoichiometric ratio (the target product Li 6 PS 5 Cl) is weighed, and then 1wt% of elemental sulfur is added to crush and mix; the mixture is transferred to a rotary sintering furnace protected by inert gas, the speed of the rotary furnace is 1m / min, the first stage heat treatment temperature is 300℃, the holding time is 60min, the second stage temperature is 550℃, the holding time is 40min, the reducing gas passed is methane gas, the third stage temperature is 550℃, the holding time is 300min, and the sulfide electrolyte is obtained after the heat treatment. Example 7

[0056] This embodiment provides a method for preparing a sulfide solid electrolyte, and the specific steps are as follows: lithium sulfate, lithium bromide, P 4 S 6 According to the stoichiometric ratio (the target product Li 6 PS 5Br) is weighed, and then 1.5wt% of elemental sulfur is added to crush and mix; the mixture is transferred to a rotary sintering furnace protected by inert gas, the speed of the rotary furnace is 1m / min, the first stage heat treatment temperature is 250℃, the holding time is 90min, the second stage temperature is 550℃, the holding time is 40min, the reducing gas passed is hydrogen sulfide gas, the third stage temperature is 500℃, the holding time is 300min, and the sulfide electrolyte is obtained after the heat treatment. Comparative Example 3

[0057] Lithium sulfide, lithium bromide, and P2S6 are mixed according to the stoichiometric ratio (target production Li 6 PS 5 Br), and then add 0.2% elemental sulfur, weigh and crush and mix; transfer the mixture to a rotary sintering furnace protected by inert gas, the rotary furnace speed is 1m / min, the sintering temperature is 500 degrees Celsius, the sintering time is 360min, and the sulfide electrolyte is obtained after cooling. Object test

[0058] 1. Test sample: the electrolyte powder prepared in each embodiment and comparative example.

[0059] 2. Test items: 2.1 Ionic conductivity test: Each sample was pressed into a sheet-like sulfide solid electrolyte material with a diameter of 10 mm and a thickness of 1 mm under the conditions of a water content of less than 10 ppm and a pressure of 200 MPa. Then, an electrochemical impedance spectroscopy (EIS) test was performed at room temperature of 25°C with carbon as the blocking electrode to calculate the ionic conductivity.

[0060] The test results of physical phase and ionic conductivity are as follows: Table 1 Phase and ionic conductivity test results Sample name Material composition Ionic conductivity mS / cm phase of matter Example 1 <![CDATA[Li 6 PS 5 Cl]]> 4.5 No impurity peak Comparative Example 1 <![CDATA[Li 6 PS 5 Cl]]> 3.8 No impurity peak Example 2 <![CDATA[Li 6 PS 5 Cl]]> 4.2 No impurity peak Example 3 <![CDATA[Li 10 GeP 2 S 12 ]]> 7.0 No impurity peak Example 4 <![CDATA[Li 10 GeP 2 S 12 ]]> 6.8 No impurity peak Comparative Example 2 <![CDATA[Li 10 GeP 2 S 12 ]]> 6.5 No impurity peak Example 5 <![CDATA[Li 6 PS 5 Cl]]> 4.0 No impurity peak Example 6 <![CDATA[Li 6 PS 5 Cl]]> 4.1 No impurity peak Example 7 <![CDATA[Li 6 PS 5 Br]]> 1.8 No impurity peak Comparative Example 3 <![CDATA[Li 6 PS 5 Br]]> 1.5 No impurity peak It can be seen from Table 1 that, compared with the sulfide electrolyte prepared using lithium sulfide as the lithium source in the comparative example, the sulfide electrolyte prepared in the embodiment of the present invention has higher ion conductivity, no impurity peak, and higher purity.

[0061] In summary, after reading the contents of this application, those skilled in the art will appreciate that the aforementioned application contents may be presented only in an exemplary manner and may not be restrictive. Although not explicitly stated herein, those skilled in the art will appreciate that this application is intended to encompass various reasonable changes, improvements and modifications to the embodiments. These changes, improvements and modifications are within the spirit and scope of the exemplary embodiments of this application.

Claims

1. A method for preparing a sulfide solid electrolyte, characterized in that: The steps include: (1) selecting a lithium source and at least three of a sulfur source, a phosphorus source, elemental sulfur, and a halogen source as raw materials and mixing them; the lithium source comprises at least one of lithium carbonate, lithium sulfate, lithium oxide, lithium hydroxide, lithium thiosulfate, and lithium sulfite; (2) placing the mixture obtained in step (1) in a sintering furnace under the protection of an inert gas, introducing a reducing gas for sintering, and obtaining the sulfide electrolyte.

2. The method for preparing a sulfide solid electrolyte according to claim 1, characterized in that: In the step (1), the sulfur source includes at least one of germanium sulfide, silicon sulfide, selenium sulfide, arsenic sulfide, iron sulfide, cobalt sulfide, nickel sulfide, and copper sulfide.

3. The method for preparing a sulfide solid electrolyte according to claim 2, characterized in that: In the step (1), the phosphorus source includes at least one of phosphorus pentasulfide, phosphorus trisulfide, tetraphosphorus nonasulfide, tetraphosphorus trisulfide, tetraphosphorus hexasulfide, tetraphosphorus pentasulfide, red phosphorus, and white phosphorus.

4. The method for preparing a sulfide solid electrolyte according to claim 3, characterized in that: In the step (1), the halogen source is at least one of lithium chloride, lithium bromide, lithium iodide, and lithium fluoride.

5. The method for preparing a sulfide solid electrolyte according to claim 1, characterized in that: The mixing in step (1) includes crushing and mixing the raw materials by ball milling or roller milling.

6. The method for preparing a sulfide solid electrolyte according to claim 1, characterized in that: In the step (1), when elemental sulfur is selected, the amount of elemental sulfur added is 0.5-5% of the total mass of the raw materials excluding elemental sulfur.

7. The method for preparing a sulfide solid electrolyte according to claim 1, characterized in that: The sintering process specifically includes three stages. The first stage maintains the temperature at 160-325 degrees Celsius and the insulation time is 60-120 minutes. The second stage maintains the temperature at 500-700 degrees Celsius and the insulation time is 30-60 minutes. The third stage maintains the temperature at 450-650 degrees Celsius and the insulation time is 240-480 minutes. The reducing gas is introduced when and only when it is in the second stage of heating.

8. The method for preparing a sulfide solid electrolyte according to claim 7, characterized in that: The reducing gas is at least one of methane, ethylene, acetylene, hydrogen sulfide, carbon disulfide, carbon monoxide, hydrogen, and sulfur monoxide, and the inert gas is nitrogen or argon.

9. The method for preparing a sulfide solid electrolyte according to claim 8, characterized in that: The rotation speed of the sintering furnace is 0.5-5m / min.

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.