KR20240079294A - Sulfide-based solid electrolyte for a secondary batteries and preparation method thereof - Google Patents

Abstract

The present invention provides a Li ₂ SP ₂ S ₅ -LiX (X is one or more types selected from the group consisting of Cl, F, Br and I) system for all-solid-state lithium secondary batteries with excellent ionic conductivity and stability, especially stability in the atmosphere. It relates to a sulfide-based solid electrolyte and a method for producing the sulfide-based solid electrolyte.

Description

Sulfide-based solid electrolyte for all-solid-state secondary batteries with improved atmospheric stability and method for manufacturing the same {SULFIDE-BASED SOLID ELECTROLYTE FOR A SECONDARY BATTERIES AND PREPARATION METHOD THEREOF}

The present invention relates to a sulfide-based solid electrolyte for an all-solid lithium secondary battery that has excellent ionic conductivity and excellent stability, especially stability in the air, and a method for manufacturing the sulfide-based solid electrolyte.

Recently, the use of lithium secondary batteries has expanded from power sources for small mobile devices to power sources for mid- to large-sized electric vehicles (xEV) and power storage systems (ESS). In particular, interest in electric vehicles, which are eco-friendly vehicles, is increasing, and major automobile companies around the world are accelerating technology development by recognizing eco-friendly electric vehicles as the next generation growth technology.

The battery specifications required for electric vehicles can take into account high power density capable of rapid charging, high energy density per weight/volume, price, safety, etc. In particular, in the case of electric vehicles, they are devices that are directly ridden and controlled by a person, so they can be operated and controlled in the event of an accident. Ensuring safety is the most important requirement. In fact, in the case of the Model S, a commercial model of Tesla, a representative electric vehicle company in the United States, several incidents of fires breaking out and burning down while driving have been announced in the media, leading to a demand for the development of all-solid-state batteries with high safety.

All-solid-state batteries consist of a solid electrolyte as well as an anode and a cathode. In other words, an all-solid-state battery is a battery in which the liquid electrolyte and separator between the battery anode and cathode are replaced with a solid electrolyte. Since it does not use flammable organic solvents, there is a low risk of fire or explosion even if an internal short circuit occurs, thereby maximizing safety and reducing the size. It can be reduced. In addition, not only is it superior in manufacturing cost and productivity, but it also has the advantage of being able to achieve high voltage by stacking it in series within a cell. Additionally, in this solid electrolyte, since only Li ions do not move, side reactions due to movement of anions do not occur, and improvements in safety and durability are expected. These all-solid-state batteries can increase safety compared to existing lithium secondary batteries.

Solid electrolytes of all-solid-state secondary batteries include polymer-based, sulfide-based, and oxide-based electrolytes. Among these, oxide-based solid electrolytes include LATP (Li _1.3 Al _0.3 Ti _1.7 (PO ₄ ) ₃ ), LLTO (Li _3x La _2/(3-x) TiO ₃ ), and LLZO (Li ₇ La ₃ Zr ₂ O ₁₂ ) systems are widely known, and while they have excellent stability compared to sulfide-based solid electrolytes, they have the disadvantage of low ionic conductivity.

Sulfide-based solid electrolytes include amorphous sulfide-based solid electrolytes or crystalline sulfide-based solid electrolytes, including LGPS (Li ₁₀ GeP ₂ S ₁₂ ), LSPSCl (Li _9.54 Si _1.7 P _1.44 S _11.7 Cl _0.3 ), Argyrodite, Li ₂ SP ₂ S ₅ , Thio-LISICON, Li-MPS (M=Si, Ge, Sn), etc., are known for their various structures and components. Sulfide ions in sulfide-based solid electrolytes have a wider gap between anions, which serve as ion conduction paths, compared to oxide ions. In addition, because the polarization rate of sulfide ions is high, the binding force for lithium ions is weak, making lithium ions more mobile, so sulfide-based solid electrolytes have the advantage of having higher ionic conductivity than oxide-based electrolytes. However, sulfide-based solid electrolytes are highly reactive with moisture, and when reacted with moisture in the air, they generate toxic H ₂ S gas, which can harm the human body, making it vulnerable to safety in the air.

International Patent Publication WO2013-073035 Public Patent Publication 2020-0052651

Sulfide-based solid electrolytes also have the problem that ionic conductivity rapidly decreases when exposed to the atmosphere. As such, if the solid electrolyte is unstable in the atmosphere, production is difficult, and control of contact with air becomes very important in the cell manufacturing process, which has the disadvantage of increasing manufacturing costs. In order to overcome the disadvantage of poor atmospheric stability of sulfide-based solid electrolytes, Publication Patent Publication 2020-0052651 uses lithium phosphate (Li ₃ PO) as a dopant in Li ₂ SP ₂ S ₅ -LiX (X is halogen)-based solid electrolyte. ₄ ) was added to provide a solid electrolyte with improved stability in the atmosphere by replacing part of the sulfur element with oxygen.

However, the stability of the electrolyte in the atmosphere has not been sufficiently improved, and lithium phosphate added as a dopant is expensive and difficult to handle, raising the price of the final solid electrolyte.

Accordingly _, the _present invention provides _a Li ₂ SP ₂ S ₅ -Li The purpose of the invention is to provide a manufacturing method thereof.

The problem to be solved by the present invention is not limited here, and other problems not mentioned will be clearly understood by those skilled in the art from the description below.

In order to achieve the above object, the present invention

_{Provided is a Li 2 SP 2 S 5 -Li}

Additionally, the present invention

Step 1) Grind and mix Li ₂ S powder, P ₂ S ₅ powder, LiX (X is one or more types selected from the group consisting of Cl, F, Br and I) powder and Cu ₃ (PO ₄ ) ₂ powder. Steps of preparing powder and

Step 2) The mixed powder is calcined to form Li ₂ SP ₂ S ₅ -LiX (X is selected from the group consisting of Cl, F, Br and I) doped with Cu ₃ (PO ₄ ) ₂ as an argyrodite crystal type dopant. Provided is a method for producing a solid electrolyte including the step of obtaining one or more sulfide-based solid electrolytes.

The sulfide-based solid electrolyte of the present invention has a high degree of crystallinity, excellent stability to lithium metal, excellent ionic conductivity, and excellent atmospheric stability, so that there is a small decrease in ionic conductivity even when exposed to oxygen. The sulfide-based solid electrolyte of the present invention has the advantage of being easy to manufacture and having excellent manufacturing costs.

Figure 1 is a configuration diagram of an all-solid-state battery.

Hereinafter, the present invention will be described in detail. Terms or words used in this specification and claims should not be construed as limited to their ordinary or dictionary meanings, and the inventor may appropriately define the concept of terms in order to explain his or her invention in the best way. It must be interpreted as meaning and concept consistent with the technical idea of the present invention based on principles.

When sulfide-based solid electrolytes come in contact with oxygen, a reaction occurs in which sulfur (S) is replaced by oxygen (O), which causes a problem in that ionic conductivity decreases. Accordingly, the present invention attempted to solve the disadvantage of the sulfide-based solid electrolyte having poor atmospheric stability, especially stability to oxygen. By doping the sulfide-based solid electrolyte with oxygen (O), oxygen (O) is maintained on the surface and inside the solid electrolyte even when exposed to the atmosphere. Atmospheric stability was improved by reducing the amount of O) substitution, and efforts were made to develop a dopant that could prevent sulfur from being substituted with oxygen in the atmosphere by doping an element that can combine with sulfur (S).

As a result, the present invention maintains the ionic conductivity of the Li ₂ SP ₂ S ₅ -LiX-based solid electrolyte prepared by adding Cu ₃ (PO ₄ ) ₂ as a dopant to the Li ₂ SP ₂ S ₅ -Li The present invention was completed after discovering that the ionic conductivity was sufficiently stable even when exposed to the atmosphere due to its stability against oxygen in the atmosphere.

The present invention _{is a} Li ₂ SP ₂ S _{5 -Li} Provides a sulfide-based solid electrolyte (X is one or more selected from the group consisting of Cl, F, Br, and I).

Cu ₃ (PO ₄ ) ₂ added as a dopant in the solid electrolyte of the present invention is believed to have a function as described below, but is not limited thereto. In other words, the oxygen (O) of Cu ₃ (PO ₄ ) ₂ added as a dopant in the solid electrolyte of the present invention exists by replacing part of the sulfur element, so that even when the solid electrolyte is exposed to oxygen in the atmosphere, oxygen remains on the surface and inside the solid electrolyte. It is thought that atmospheric stability is improved by reducing the amount of (O) substitution. Furthermore, Cu ₃ (PO ₄ ) ₂ copper is thought to prevent sulfur (S) from being replaced by oxygen in the air even when the solid electrolyte is exposed to oxygen in the air through the Cu-S bond.

In the present invention, the mole percent of dopant Cu ₃ (PO ₄ ) ₂ doped into the entire solid electrolyte is 0.01 to 10 mol%, preferably 0.1 to 1 mol%. When a solid electrolyte is produced by mixing dopants in the above amount, there is an effect of sufficiently increasing atmospheric stability without reducing lithium ion conductivity. If the dopant is used in less than 0.01 mol%, atmospheric stability cannot be increased, and if the dopant is used in more than 10 mol%, lithium ion conductivity may be reduced, which is not desirable.

In the Li ₂ SP ₂ S ₅ -Li At least one selected from the group consisting of, preferably selected from the group consisting of chlorine element (Cl) or chlorine element (Cl) together with fluorine element (F), bromine element (Br) and iodine element (I). It may contain one or more types of halogen.

The D50 of the Li ₂ SP ₂ S ₅ -LiX-based sulfide-based solid electrolyte particles doped with the dopant Cu ₃ (PO ₄ ) ₂ of the present invention may be 0.5 to 20 μm. When the D50 of the particle is 0.5 to 20㎛, it can have appropriate ionic conductivity.

_The Li _{2 SP 2 S 5 -Li} When exposed for 24 hours under room), the ionic conductivity reduction rate calculated by the following equation (1) is less than 30%. _{The Li 2 SP 2} S ₅ -Li

Equation (1)

In _one embodiment of the present invention _{, a} Li ₂ SP ₂ S ₅ -Li The solid electrolyte may be a compound of the following formula (1).

Chemical formula (1)

Li _(7-x)(1-y) Cu _3y P _(1+y) S _{(6-x)(1-y) O 8y}

In the above equation

x is 0.5 ≤ x ≤ 2,

y is 0.0001 ≤ y ≤ 0.1.

The y is the number of moles of dopant Cu ₃ (PO ₄ ) ₂ doped in 1 mole of the total solid electrolyte and is 0.0001 to 0.1, preferably 0.0001 to 0.01.

The solid electrolyte of the present invention may have a cubic azirodite-type crystal structure.

The present invention is a method for producing the sulfide-based solid electrolyte.

Step 1) Grind and mix Li ₂ S powder, P ₂ S ₅ powder, LiX (X is at least one selected from the group consisting of Cl, F, Br and I) powder and Cu ₃ (PO ₄ ) ₂ powder. Steps of preparing powder and

Step 2) Calcining the mixed powder to obtain _an argyrodite crystalline sulfide-based _solid electrolyte _. Li ₂ SP ₂ S ₅ -Li Provides a manufacturing method.

Step 1) is grinding and mixing Li ₂ S powder, P ₂ S ₅ powder, LiX (X is one or more selected from the group consisting of Cl, F, Br and I) powder and Cu ₃ (PO ₄ ) ₂ powder This is the step of preparing mixed powder.

The mixing can be performed by milling, and milling is preferably performed by mechanical milling such as an attrition mill or ball mill to achieve uniform mixing. Milling can be carried out under inert gas conditions. In the case of a ball mill, zirconia balls with a particle size of 1 to 10 mm can be used for mixing, and two or more balls with different particle sizes can be mixed. For example, balls with a particle diameter of 1 to 3 mm and balls with a particle diameter of 5 to 10 mm can be mixed and used in a ratio of 1:10 to 10:1, preferably 2:8 to 8:2.

Milling may be performed at a speed of 100 to 600 rpm for 10 to 50 hours, preferably 15 to 30 hours. If the grinding time is less than 10 hours, grinding is not sufficient, and if it is longer than 50 hours, there may be problems such as a decrease in ionic conductivity due to a decrease in particle size.

The weight ratio of the Li ₂ S powder, P ₂ S ₅ powder, and LiX powder mixed is preferably 30 to 40:35 to 50:15 to 27, more preferably 33 to 40:38 to 45:19 to 25. am. When the weight ratio of the mixed Li ₂ S powder, P ₂ S ₅ powder, and Li Electrolytes can be manufactured.

Step 2) is a step of heat treating the mixed powder under argon (Ar), an inert atmosphere, to produce a solid electrolyte doped with copper and oxygen.

Step 2) is to place the mixed powder in a quartz crucible and sinter it in an electric furnace in an Ar gas atmosphere at 450-550°C for 5-15 hours to obtain Li ₂ SP ₂ S ₅ -LiX (X=Cl, F, Br, I from the group consisting of This is the step of manufacturing one or more selected sulfide-based solid electrolytes.

Step 2) may include a subsequent classification step.

The present invention provides an all-solid lithium secondary battery containing the sulfide-based solid electrolyte of the present invention. That is, the sulfide-based solid electrolyte of the present invention can be used as a solid electrolyte layer of an all-solid-state lithium secondary battery or a solid electrolyte mixed into a positive electrode/negative electrode mixture, etc.

In one embodiment, an all-solid lithium secondary battery can be constructed by forming a layer containing the above solid electrolyte between the positive electrode, the negative electrode, and the positive electrode and the negative electrode.

The solid electrolyte of the present invention has high crystallinity and excellent stability to lithium metal and excellent ionic conductivity, thereby providing a stable and efficient all-solid-state lithium secondary battery.

Here, the layer containing the solid electrolyte can be created, for example, by dropping a slurry consisting of a solid electrolyte, a binder, and a solvent onto a base, cutting it by rubbing it with a doctor blade, etc., or by bringing the base and the slurry into contact with air. It can be produced by cutting with a knife or screen printing to form a coating film, followed by heat drying to remove the solvent. Alternatively, it can be produced by producing a green compact from the powder of the solid electrolyte by pressing, etc., and then processing it.

As the cathode material for the all-solid-state lithium secondary battery of the present invention, any cathode material used as a cathode active material for lithium secondary batteries can be used without limitation. Examples of the positive electrode active material include spinel-type lithium transition metal oxide, lithium transition metal oxide with a layered structure, olivine, or a mixture of two or more types thereof.

As the negative electrode material for the all-solid-state lithium secondary battery of the present invention, any negative electrode material used as a negative electrode active material for lithium secondary batteries can be used without limitation. For example, carbon-based materials such as artificial graphite, natural graphite, and non-graphitizable carbon (hard carbon) can be used as the negative electrode active material. Therefore, by using this solid electrolyte as the electrolyte of the lithium secondary battery and using a carbon-based material as the negative electrode active material, the energy density of the all-solid-state lithium secondary battery can be greatly improved. Additionally, silicon active material, which is a high-capacity negative electrode material, can be used as the negative electrode active material.

Hereinafter, the present invention will be described with reference to an embodiment of the present invention. However, the present invention is not limited thereto, and in describing the present invention, descriptions of already known functions or configurations will be omitted to make the gist of the present invention clear.

Example 1. Preparation of sulfide-based solid electrolyte doped with Cu ₃ (PO ₄ ) ₂

Lithium sulfide (Li ₂ S) powder, phosphorus pentasulfide (P ₂ S ₅ ) powder, lithium chloride (LiCl) powder, and Cu ₃ (PO ₄ ) ₂ were weighed in the amounts shown in Table 1 below, and placed in a ball mill pot under an inert gas. Add it together with the mixing bowl. Mixed powder is prepared by grinding and mixing for 24 hours at a speed of 250 rpm using ball mill equipment. This mixed powder is placed in a quartz crucible and fired in an electric furnace at 510°C in an Ar gas atmosphere for 10 hours. Afterwards, a sample was obtained to obtain a powdery solid electrolyte azirodite crystalline sulfide-based compound.

Comparative Example 1. Preparation of dopant-free sulfide-based solid electrolyte

An azirodite crystalline sulfide-based compound for a solid electrolyte was obtained in the same manner as in Example 1 using lithium sulfide (Li ₂ S) powder, phosphorus pentasulfide (P ₂ S ₅ ) powder, and lithium chloride (LiCl) powder.

Comparative Examples 2 to 4. Preparation of sulfide-based solid electrolytes using different types of dopant.

Instead of Cu ₃ (PO ₄ ) ₂ , Li ₃ PO ₄ (Comparative Example 2), Na ₃ PO ₄ (Comparative Example 3), and Sr ₃ (PO ₄ ) ₂ (Comparative Example 4) were added in the amounts shown in Table 1 below. An azirodite crystalline sulfide-based compound of a solid electrolyte was obtained in the same manner as in Example 1, except that this was performed.

Examples 2 to 5. Preparation of sulfide-based solid electrolytes with different contents of Cu ₃ (PO ₄ ) ₂

As shown in Table 1 below, an azyrodite crystalline sulfide-based compound for a solid electrolyte was obtained in the same manner as in Example 1, except that the content of Cu ₃ (PO ₄ ) ₂ was changed.

Examples 6 to 9. Preparation of sulfide-based solid electrolytes with different Cu ₃ (PO ₄ ) ₂ content and solid electrolyte composition

As shown in Table 1 below, except that the contents of Cu ₃ (PO ₄ ) ₂ and lithium sulfide (Li ₂ S) powder, phosphorus pentasulfide (P ₂ S ₅ ) powder, and lithium chloride (LiCl) powder were changed. By carrying out the same procedure as Example 1, an azirodite crystalline sulfide-based compound of a solid electrolyte was obtained.

Furtherance　 Li ₂ S P ₂ S ₅ LiCl Li ₃ P O _{4 Na3PO4 ​} Cu ₃ (PO ₄ ) ₂ Sr ₃ (PO ₄ ) ₂ Example 1 Cu ₃ (PO ₄ ) ₂ 1mol% + Ref. 99mol% 19.23 20.62 9.44 　 　 0.71 　 Comparative Example 1 Ref. (Li _5.76 PS _4.76 Cl _1.24 ) 19.5 20.92 9.58 Comparative Example 2 Li ₃ PO ₄ 1mol% +
Ref. 99mol% 19.42 20.83 9.53 0.22 　 　 　 Comparative Example 3 Na ₃ PO ₄ 1mol% +
Ref. 99mol% 19.38 20.79 9.52 　 0.31 　 　 Comparative Example 4 Sr ₃ (PO ₄ ) ₂ 1mol% + Ref. 99mol% 19.17 20.57 9.41 　 　 　 0.85 Example 2 Cu ₃ (PO ₄ ) ₂ 0.1mol% + Ref. 99.9mol% 19.48 20.89 9.56 0.07 Example 3 Cu ₃ (PO ₄ ) ₂ 0.3mol% + Ref. 99.7mol% 19.42 20.83 9.53 0.21 Example 4 Cu ₃ (PO ₄ ) ₂ 0.5mol% + Ref. 99.5mol% 19.36 20.77 9.51 0.36 Example 5 Cu ₃ (PO ₄ ) ₂ 0.7mol% + Ref. 99.3mol% 19.31 20.71 9.48 0.50 Example 6 Cu ₃ (PO ₄ ) ₂ 0.1mol% + Li _5.5 PS _4.5 Cl _1.5 99.9mol% 17.21 20.81 11.91 0.07 Example 7 Cu ₃ (PO ₄ ) ₂ 0.3mol% + Li _5.5 PS _4.5 Cl _1.5 99.7mol% 17.16 20.75 11.87 0.21 Example 8 Cu ₃ (PO ₄ ) ₂ 0.5mol% + Li _5.5 PS _4.5 Cl _1.5 99.5mol% 17.11 20.69 11.84 0.36 Example 9 Cu ₃ (PO ₄ ) ₂ 0.7mol% + Li _5.5 PS _4.5 Cl _1.5 99.3mol% 17.06 20.63 11.81 0.50

Unit: g

Experimental Example 1. Ion conductivity measurement

- Evaluation equipment and conditions: Zahner Zennium impedance analyzer (50 mV, 1 mHz ~ 4 MHz / room temperature)

Prepare a sample inside the glove box and prepare an ionic conductivity measurement cell. Measure the thickness before and after adding the solid electrolyte to the ionic conductivity cell. After adding 0.4 g of the solid electrolytes of Example 1 and Comparative Examples 1 to 4, a force of 5 tons was applied to manufacture the cell, and the ionic conductivity was measured using an impedance analyzer and is listed in Table 2 (before exposure).

Experimental Example 2. Atmospheric stability measurement

The ionic conductivity of the solid electrolytes of Example 1 and Comparative Examples 1 to 4 was measured after exposure to air for 24 hours at a temperature of 21 to 23°C and a dew point of -45 to -65°C in a dry room filled with air from which moisture had been removed. and are listed in Table 2 (after exposure). The reduction rate of ionic conductivity was calculated using the following formula.

Equation (1)

Solid electrolyte type dopant Lithium ion conductivity (mS/cm) type Content (mol%) Before exposure After exposure decline rate Example 1 Li _5.76 PS _4.76 Cl _1.24 Cu ₃ (PO ₄ ) ₂ 1mol% 2.85 2.03 -28.8% Comparative Example 1 - - 3.72 2.41 -35.2% Comparative Example 2 Li ₃ P O ₄ 1mol% 2.98 2.02 -32.2% Comparative Example 3 _{Na3PO4 ​} 1mol% 2.28 1.47 -35.5% Comparative Example 4 Sr ₃ (PO ₄ ) ₂ 1mol% 2.2 1.14 -48.2%

It can be seen that the solid electrolyte of Example 1 showed a lower decrease in ionic conductivity when exposed to the atmosphere of a dry room compared to the solid electrolyte of Comparative Example 1. In addition, it can be seen that the decrease in ionic conductivity is small compared to the case where other phosphates including Li ₃ PO ₄ are added. That is, the solid electrolyte of the present invention has excellent atmospheric stability.

Experimental Example 3. Confirmation of atmospheric stability according to the amount of dopant added

Cells were prepared for the solid electrolytes of Examples 2 to 9, and ionic conductivity was measured (before exposure). Afterwards, the cell was exposed to air for 24 hours in a dry room filled with moisture-removed air at a temperature of 21 to 23°C and a dew point of -45 to -65°C. The ionic conductivity was measured and listed in Table 3 (after exposure) ). The reduction rate of ionic conductivity was calculated.

Solid electrolyte type dopant　 Lithium ion conductivity (mS/cm) type Content (mol%) Before exposure After exposure decline rate Comparative Example 1 Ref.
(Li _5.76 PS _4.76 Cl _1.24 ) - - 3.72 2.41 -35.2% Example 2 Li _5.76 PS _4.76 Cl _1.24 Cu ₃ (PO ₄ ) ₂ 0.1mol% 3.50 2.82 -19.4% Example 3 0.3mol% 4.07 3.85 -5.4% Example 4 0.5mol% 3.84 3.25 -15.4% Example 5 0.7mol% 4.34 3.29 -24.2% Example 6 Li _5.5 PS _4.5 Cl _1.5 Cu ₃ (PO ₄ ) ₂ 0.1mol% 5.57 4.87 -12.57% Example 7 0.3mol% 6.02 5.1 -15.3% Example 8 0.5mol% 6.09 4.65 -23.6% Example 9 0.7mol% 5.90 4.42 -25.8%

According to Table 3 _, it can be seen that even when the composition ratio of the solid electrolyte was changed _, the degree of decrease in ionic conductivity after exposure of the solid electrolyte to the air was reduced compared to Comparative Example 1 due to the addition of Cu 3 (PO 4 ) ₂ dopant. In other words, it can be seen that the solid electrolyte of the present invention has high stability in the atmosphere.

Claims (12)

Li ₂ SP ₂ S ₅ -LiX (X is one or more selected from the group consisting of Cl, F, Br and I) sulfide-based solid electrolyte doped with Cu ₃ (PO ₄ ) ₂ as a dopant. The sulfide-based solid electrolyte according to claim 1, wherein the mole percent of the dopant Cu ₃ (PO ₄ ) ₂ doped in the entire solid electrolyte is 0.01 to 10 mol%. The method of claim 1, wherein Containing a sulfide-based solid electrolyte. The method of claim 1, wherein when the sulfide-based solid electrolyte is exposed to dry air (dry room) at a temperature of 21 to 23°C and a dew point of -45 to -65°C for 24 hours, the ionic conductivity calculated by the following equation (1) A sulfide-based solid electrolyte with a reduction rate of 30% or less.
Equation (1)
The sulfide-based solid electrolyte according to claim 1, wherein the sulfide-based solid electrolyte is a compound of the following formula (1).
Chemical formula (1)
Li _(7-x)(1-y) Cu _3y P _(1+y) S _{(6-x)(1-y) O 8y}
In the above equation,
X is one or more selected from the group consisting of Cl, F, Br and I,
x is 0.5 ≤ x ≤ 2,
y is 0.0001 ≤ y ≤ 0.1. Step 1) Grind and mix Li ₂ S powder, P ₂ S ₅ powder, LiX (X is one or more types selected from the group consisting of Cl, F, Br and I) powder and Cu ₃ (PO ₄ ) ₂ powder. Steps of preparing powder and
Step 2) Calcining _the mixed powder _to obtain _a Li ₂ SP ₂ S ₅ -Li How to manufacture. The method of producing a sulfide-based solid electrolyte according to claim 6, wherein the mixing in step 1) is performed by an attrition mill or a ball mill. The method of claim 7, wherein the mixing in step 1) is performed by a ball mill, and two or more balls with different particle sizes are mixed and used. The method of claim 6, wherein the weight ratio of Li ₂ S powder, P ₂ S ₅ powder, and LiX powder mixed in step 1) is 30 to 40:35 to 50:15 to 27. The method of claim 8, wherein the mixing in step 1) is performed at a speed of 100 to 600 rpm for 10 to 50 hours. The method of claim 6, wherein in step 2), the mixed powder is placed in a quartz crucible and fired at 450-550°C for 5-15 hours in an electric furnace in an Ar gas atmosphere. An all-solid lithium secondary battery comprising the sulfide-based solid electrolyte of claim 1 or the Li ₂ SP ₂ S ₅ -LiX-based sulfide-based solid electrolyte doped with Cu ₃ (PO ₄ ) ₂ manufactured by the manufacturing method of claim 6.