Method for producing solid electrolyte and solid electrolyte

Abstract

The present invention relates to a method for producing a sulfide-based solid electrolyte, the method including the steps of (A) grinding and then mixing raw materials for a sulfide-based solid electrolyte to produce a reaction mixture, (B) compressing the reaction mixture into a pellet, and (C) firing the pellet-shaped reaction mixture to produce a fired product, and a sulfide-based solid electrolyte produced thereby.

Description

[Technical Field]

[0001] This application claims the benefit of priority based on Korean Patent Application Nos. 10-2022-0117225 and 10-2022-0117226, filed September 16, 2022, and all contents disclosed in the documents of said Korean patent applications are incorporated herein by reference.

[0002] The present invention relates to a method for producing a sulfide-based solid electrolyte and a solid electrolyte produced thereby. [Background technology]

[0003] All-solid-state batteries replace the liquid electrolyte currently used between the positive and negative electrodes of lithium secondary batteries with a solid electrolyte. These batteries are safe and explosion-free, and have a higher energy density than conventional batteries, drawing attention as a next-generation battery. The solid electrolyte used in all-solid-state batteries is a solid-state material that allows lithium ions to be conducted within the battery, and has high ionic conductivity comparable to that of the liquid electrolytes currently used in lithium secondary batteries. Key materials for solid electrolytes include polymers, sulfides, and oxides. Among these, sulfide-based solid electrolytes, which are highly flexible and have high ionic conductivity, are considered suitable for the production of large-capacity batteries.

[0004] Meanwhile, sulfide-based solid electrolytes are generally produced by simply mixing raw materials and then heat-treating them. However, in this process, not only unreacted materials but also by-reactants, i.e., impurities, are present in the raw materials, which reduces the ionic conductivity of the sulfide-based solid electrolyte.

[0005] In particular, when the basic composition of Li6PS5Ha (Ha:Cl, Br, I) is deviated from, there is a problem that the content of impurities increases further due to structural instability. Summary of the Invention [Problem to be solved by the invention]

[0006] The problem to be solved by the present invention is to provide a method for manufacturing a sulfide-based solid electrolyte that improves the reactivity of raw materials and results in a sulfide-based solid electrolyte that contains almost no impurities, and a sulfide-based solid electrolyte manufactured thereby. [Means for solving the problem]

[0007] The present invention provides a method for producing a sulfide-based solid electrolyte and a sulfide-based solid electrolyte.

[0008] (1) The present invention provides a method for producing a sulfide-based solid electrolyte, comprising the steps of: (A) grinding and then mixing raw materials for a sulfide-based solid electrolyte to produce a reaction mixture; (B) compressing the reaction mixture into a pellet; and (C) calcining the pellet-shaped reaction mixture to produce a calcined product.

[0009] (2) The present invention provides a method for producing a sulfide-based solid electrolyte according to (1) above, wherein the sulfide-based solid electrolyte raw material comprises one or more selected from (i) a lithium-containing raw material, (ii) a phosphorus-containing raw material, (iii) a sulfur-containing raw material, and, optionally, (iv) a halogen-containing raw material, an M-containing raw material (M is one or more selected from Si and Ge), and an N-containing raw material (N is one or more selected from Sn, Sb, Al, Ga, Zn, Zr, In, and Cu).

[0010] (3) The present invention provides a method for producing a sulfide-based solid electrolyte according to (1) or (2), wherein the pulverization in step (A) is ball mill pulverization using two or more types of balls having different diameters.

[0011] (4) The present invention provides the method for producing a sulfide-based solid electrolyte according to (3) above, wherein the diameter of the balls used in the grinding in step (A) is 1 mm, 3 mm, or 5 mm.

[0012] (5) The present invention provides a method for producing a sulfide-based solid electrolyte according to any one of the above (1) to (4), wherein the pulverization in the step (A) is carried out at a rotation speed of 500 rpm to 800 rpm.

[0013] (6) The present invention provides a method for producing a sulfide-based solid electrolyte according to any one of (1) to (5) above, wherein the mixing in step (A) is performed by ball mill mixing using two or more types of balls having different diameters.

[0014] (7) The present invention provides the method for producing a sulfide-based solid electrolyte according to (6), wherein the diameter of the balls during mixing in step (A) is 1 mm, 3 mm, 5 mm, or 10 mm.

[0015] (8) The present invention provides a method for producing a sulfide-based solid electrolyte according to any one of the above (1) to (7), wherein the mixing in the step (A) is carried out at a rotation speed of 200 rpm to 500 rpm.

[0016] (9) The present invention provides a method for producing a sulfide-based solid electrolyte according to any one of (2) to (8), wherein the (iv) halogen-containing raw material contains a chlorine-containing raw material and a bromine-containing raw material, and the ratio of the number of moles of halogen to the total number of moles of phosphorus, M, and N contained in the reaction mixture is 1.1 or more and 1.5 or less.

[0017] (10) The present invention provides a method for producing a sulfide-based solid electrolyte according to any one of (1) to (9), wherein a non-reactive solvent having a relative polarity to water of 0 to 0.15 is further mixed during the production of the reaction mixture.

[0018] (11) The present invention provides the method for producing a sulfide-based solid electrolyte according to (10), wherein the non-reactive solvent is mixed in an amount of 2.5 wt % to 5.0 wt % based on the total amount of the sulfide-based solid electrolyte raw materials.

[0019] (12) The present invention provides the method for producing a sulfide-based solid electrolyte according to any one of (1) to (11), wherein the compression in the step (B) is performed at a pressure of 50 MPa to 400 MPa.

[0020] (13) The present invention provides the method for producing a sulfide-based solid electrolyte according to any one of (1) to (12) above, wherein the firing is carried out at a temperature of 350°C to 600°C.

[0021] (14) The present invention provides a method for producing a sulfide-based solid electrolyte according to any one of (1) to (13) above, further comprising the step (D) of pulverizing the fired product.

[0022] (15) The present invention provides the method for producing a sulfide-based solid electrolyte according to (14), wherein the pulverization in step (D) comprises pulverizing the fired product in a mortar and then pulverizing the fired product in a ball mill using two or more types of balls having different diameters.

[0023] (16) The present invention provides the method for producing a sulfide-based solid electrolyte according to (15), wherein the diameter of the balls used in the pulverization in step (D) is 1 mm, 3 mm, 5 mm, or 10 mm.

[0024] (17) The present invention provides the method for producing a sulfide-based solid electrolyte according to any one of (14) to (16), wherein the pulverization in the step (D) is carried out at a rotation speed of 100 rpm to 500 rpm.

[0025] (18) The present invention provides a sulfide-based solid electrolyte having a composition represented by the following chemical formula 1, in which the total content of impurities is 3% by weight or less: [Chemical formula 1] Li 7-(x+y)+((a×(5-p))+(b×(5-q))) P 1-(a+b) M a N b S 6-(x+y) Cl x Br y In the above Chemical Formula 1, M is at least one selected from Si and Ge, N is one or more selected from Sn, Sb, Al, Ga, Zn, Zr, In and Cu, p is the oxidation number of M, q is the oxidation number of N, 0.1≦x≦1.4, 0.1≦y≦1.4, 1.1 <x+y≦1.5、0≦a≦0.5、0≦b≦0.2である。

[0026] (19) The present invention provides the sulfide-based solid electrolyte according to the above (18), wherein the sulfide-based solid electrolyte has an ionic conductivity of 4.0 mS / cm or more.

[0027] (20) The present invention is characterized in that, in the above (18) or (19), the sulfide-based solid electrolyte has an electronic conductivity of 1.0 × 10 -9 mS / cm ~ 1.0 × 10 -4 We provide a sulfide-based solid electrolyte with a conductivity of 0.1 mS / cm.

[0028] (21) In any one of the above (18) to (20), the present invention is characterized in that the sulfide-based solid electrolyte has an average particle size (D 50 ) is 1.0 μm to 5.0 μm. [Effects of the Invention]

[0029] In the method for producing a sulfide-based solid electrolyte according to the present invention, raw materials are first pulverized and then mixed to prepare a reaction mixture, which is then compressed and processed into pellets, and then calcined. This not only prevents the raw materials from sticking together, but also improves the reactivity of the raw materials.

[0030] Therefore, the sulfide-based solid electrolyte produced by the method for producing a sulfide-based solid electrolyte according to the present invention has the advantage of being almost free of impurities and having excellent physical properties such as ionic conductivity. DETAILED DESCRIPTION OF THE INVENTION

[0031] The present invention will be described in more detail below to facilitate understanding of the present invention. The terms and words used in the specification and claims should not be interpreted as being limited to their ordinary or dictionary meanings, but should be interpreted as meanings and concepts that are consistent with the technical idea of ​​the present invention, based on the principle that the inventors can appropriately define the concepts of terms to best describe their inventions.

[0032] The terms used in this specification are merely used to describe exemplary embodiments and are not intended to limit the present invention. The singular expressions include the plural expressions unless the context clearly indicates otherwise.

[0033] In this specification, the terms "comprises," "includes," "has," and the like are intended to specify the presence of embodied features, numbers, steps, components, or combinations thereof, but are not intended to preclude the possible presence or addition of one or more different features, numbers, steps, components, or combinations thereof.

[0034] In this specification, "D n " means the particle size at n% point of the volume cumulative distribution by particle size. That is, D 50 is the particle size at the 50% point of the volume cumulative distribution by particle size, and D 90 is the particle size at 90% of the volume cumulative distribution by particle size, and D 10 is the particle size at the 10% point of the volume cumulative distribution of particle size. n can be measured using the laser diffraction method. Specifically, the powder to be measured is dispersed in a dispersion medium (xylene), and then introduced into a commercially available laser diffraction particle size measuring device (for example, the Mastersizer 3000 manufactured by Malvern Panalyticl). When the particles pass through the laser beam, the difference in the diffraction pattern due to particle size is measured to calculate the particle size distribution. By calculating the particle diameters at the 10%, 50%, and 90% points of the cumulative volume distribution due to particle size in the measuring device, D10 , D 50 and D 90 can be measured.

[0035] In this specification, the relative polarity of a solvent to water means the polarity of the solvent when the polarity of water is set to 1. For example, the relative polarity of xylene to water is 0.074, the relative polarity of toluene to water is 0.099, and the relative polarity of hexane to water is 0.009.

[0036] The term "all solid state battery" as used herein means a battery in which all components of the battery are solid, and is distinguished from liquid electrolyte secondary batteries that use a liquid electrolyte such as an electrolytic solution, and gel polymer secondary batteries that use a polymer electrolyte instead of a separator and a liquid electrolyte together.

[0037] Method for producing sulfide-based solid electrolyte The method for producing a sulfide-based solid electrolyte according to the present invention includes the steps of: (A) grinding and then mixing raw materials for a sulfide-based solid electrolyte to produce a reaction mixture; (B) compressing the reaction mixture into a pellet; and (C) calcining the pellet-shaped reaction mixture to produce a calcined product.

[0038] The method for producing a sulfide-based solid electrolyte according to the present invention may further include the step (D) of pulverizing the fired product.

[0039] Hereinafter, each step of the method for manufacturing a sulfide-based solid electrolyte according to the present invention will be described.

[0040] (A) Step The step (A) is a step of separately pulverizing the sulfide-based solid electrolyte raw materials and then mixing them to prepare a reaction mixture.

[0041] According to the present invention, the sulfide-based solid electrolyte precursor material can include one or more selected from (i) a lithium-containing precursor material, (ii) a phosphorus-containing precursor material, (iii) a sulfur-containing precursor material, and, optionally, (iv) a halogen-containing precursor material, an M-containing precursor material (wherein M is at least one selected from Si and Ge), and an N-containing precursor material (wherein N is at least one selected from Sn, Sb, Al, Ga, Zn, Zr, In, and Cu). Specifically, the sulfide-based solid electrolyte precursor material can be one or more selected from (i) a lithium-containing precursor material, (ii) a phosphorus-containing precursor material, (iii) a sulfur-containing precursor material, and, optionally, (iv) a halogen-containing precursor material, an M-containing precursor material (wherein M is at least one selected from Si and Ge), and an N-containing precursor material (wherein N is at least one selected from Sn, Sb, Al, Ga, Zn, Zr, In, and Cu).

[0042] Specifically, step (A) may be a step of independently ball milling (i) a lithium-containing source material, (ii) a phosphorus-containing source material, (iii) a sulfur-containing source material, and optionally (iv) one or more selected from a halogen-containing source material, an M-containing source material (where M is at least one selected from Si and Ge), and an N-containing source material (where N is at least one selected from Sn, Sb, Al, Ga, Zn, Zr, In, and Cu) using a planetary ball mill and then mixing them to produce a reaction mixture. For example, before mixing LiS, P2S5, and optionally one or more selected from LiCl, LiBr, SiS2, and SnS2, each of these may be milled using zirconia balls and then mixed to produce a reaction mixture. In this case, the surface area of ​​the source materials may be increased, improving reactivity, and as a result, the sulfide-based solid electrolyte produced may contain almost no impurities. On the other hand, when a sulfide-based solid electrolyte is produced by mixing raw materials without first grinding them, the raw materials may be mixed unevenly and solidify, resulting in partial compositional non-uniformity and the remaining of many impurities. That is, since some raw materials cause solidification, when the raw materials used to produce the solid electrolyte are first ground and then mixed, the particle size of the raw materials can be adjusted to be smaller and the reactivity can be improved, compared to when the raw materials are mixed without grinding.

[0043] For reference, when raw materials are mixed in a process for producing a sulfide-based solid electrolyte, the sulfur-containing raw materials may adhere to the wall of a pulverizer (e.g., a ball mill container) causing a sticking phenomenon, which may result in the generation of impurities, resulting in sulfur deficiency and a decrease in ionic conductivity. However, in the present invention, the raw materials are first pulverized and then mixed as described above, thereby efficiently suppressing the sticking phenomenon and thereby improving the ionic conductivity of the produced solid electrolyte.

[0044] According to the present invention, the (i) lithium-containing raw material may be, but is not limited to, LiS, LiS, LiS, LiS, LiCl, LiBr, Li, LiPS, LiOH, LiCO, or a combination thereof. The (i) lithium-containing raw material may be mixed in an amount such that the resulting sulfide-based solid electrolyte has a composition represented by Chemical Formula 1 described herein.

[0045] According to the present invention, the (ii) phosphorus-containing raw material may be, but is not limited to, P2S5, Li3PS4, or a combination thereof, and may be mixed in an amount such that the resulting sulfide-based solid electrolyte has a composition represented by Chemical Formula 1 described herein.

[0046] According to the present invention, the sulfur-containing raw material (iii) may be, but is not limited to, LiS, LiS2, LiS4, LiS6, S8, P2S5, Li3PS4, or a combination thereof. The sulfur-containing raw material (iii) may be mixed in an amount such that the resulting sulfide-based solid electrolyte has a composition represented by Chemical Formula 1 described herein.

[0047] According to the present invention, the halogen-containing source material may be, but is not limited to, LiCl (a chlorine-containing source material), LiBr (a bromine-containing source material), or a combination thereof. The halogen-containing source material may be mixed in an amount such that the resulting sulfide-based solid electrolyte has a composition represented by Formula 1 described herein.

[0048] According to the present invention, the M-containing raw material (M is at least one selected from Si and Ge) is SiS2, SiCl4, SiBr4, Li 3.75 Si, Si3P4, GeS2, GeCl4, GeBr4, Li 3.75The M-containing raw material may be, but is not limited to, Ge, Ge3P4, or a combination thereof. The M-containing raw material may be mixed in an amount such that the resulting sulfide-based solid electrolyte has a composition represented by Formula 1 described herein.

[0049] According to the present invention, the N-containing raw material (N is at least one selected from Sn, Sb, Al, Ga, Zn, Zr, In and Cu) is NS q / 2 , NBr q , NCl q , N 3 / q P, NP, or a combination thereof (q is the oxidation number of N). Specifically, SnS2, SnCl4, SnBr4, Sn 3 / 4 P, SbS 2.5 , SbCl5, SbBr5, SbP, AlS 1.5 , AlCl3, AlBr3, AlP, GaS 1.5 , GaCl3, GaBr3, GaP, ZnS, ZnCl2, ZnBr2, Zn 1.5 P, ZrS2, ZrCl4, ZrBr4, ZrP, InS 1.5 , InCl3, InBr3, InP, CuS, CuCl2, CuBr2, Cu 1.5 The N-containing raw material may be, but is not limited to, P. The N-containing raw material may be mixed in an amount such that the resulting sulfide-based solid electrolyte has a composition represented by Chemical Formula 1 described herein.

[0050] When the reaction mixture contains an M-containing raw material (M is at least one selected from Si and Ge) and an N-containing raw material (N is at least one selected from Sn, Sb, Al, Ga, Zn, Zr, In, and Cu), the resulting sulfide-based solid electrolyte is doped with M and N, which can further improve the ionic conductivity and water stability.

[0051] According to the present invention, the pulverization in step (A) may be ball mill pulverization using two or more types of balls with different diameters. When two or more types of balls with different diameters are used, all particles can be uniformly pulverized into fine powder. The material of the balls may be the same as that of the ball mill container, such as zirconia, stainless steel, tungsten carbide, silicon nitride, etc.

[0052] According to the present invention, when the pulverization in step (A) is performed using two or more balls with different diameters, the diameter of the balls may be 1 mm, 3 mm, or 5 mm. The energy applied to the particles is determined depending on the diameter of the balls. When the diameter of the balls used in the pulverization in step (A) is 1 mm, 3 mm, or 5 mm, all particles can be uniformly pulverized without exception. That is, balls with a relatively large diameter can pulverize large particles with relatively strong energy, and balls with a relatively small diameter can further reduce the particle size of the raw material.

[0053] For example, the pulverization in step (A) can be performed using two or more types of zirconia balls having different diameters. More specifically, the pulverization in step (A) can be performed using zirconia balls having a diameter of 1 mm and zirconia balls having a diameter of 3 mm to pulverize the raw material into particles having an average particle size (D 50 ) can be pulverized to 1 μm or less.

[0054] According to the present invention, the milling in step (A) can be performed at a rotation speed of 500 rpm to 800 rpm. Specifically, the milling in step (A) can be performed at a rotation speed of 500 rpm or more, 510 rpm or more, 520 rpm or more, 530 rpm or more, 540 rpm or more, 550 rpm or more, 560 rpm or more, 570 rpm or more, 580 rpm or more, 590 rpm or more, or 600 rpm or more, and 700 rpm or less, 710 rpm or less, 720 rpm or less, 730 rpm or less, 740 rpm or less, 750 rpm or less, 760 rpm or less, 770 rpm or less, 780 rpm or less, 790 rpm or less, or 800 rpm or less. In this case, a rotation speed above a predetermined level is ensured, which facilitates milling of the raw materials by the balls and effectively reduces the size of each raw material. The grinding in step (A) is preferably carried out at a high rotation speed using balls with smaller particle diameters, by grinding each raw material separately, compared to the mixing in step (A) in which the raw materials are mixed.

[0055] The mixing in step (A) may be ball mill mixing using two or more balls with different diameters, which may allow the raw materials to be mixed more uniformly. The material of the balls may be the same as that of the ball mill container, such as zirconia, stainless steel, tungsten carbide, silicon nitride, etc.

[0056] According to the present invention, when the mixing in step (A) is performed using two or more balls with different diameters, the diameter of the balls may be 1 mm, 3 mm, 5 mm, or 10 mm. Even if pre-milling is performed, further milling is performed in the mixing step. Among the raw materials to be mixed, larger particle diameters are mainly milled by the larger diameter balls, and smaller particle diameters are mainly milled by the smaller diameter balls, resulting in uniform particle diameters and good mixing.

[0057] For example, the mixing in step (A) can be performed using two or more types of zirconia balls with different diameters. More specifically, the mixing in step (A) can be performed using zirconia balls with a diameter of 3 mm and zirconia balls with a diameter of 5 mm.

[0058] According to the present invention, the mixing in step (A) can be performed at a rotation speed of 200 rpm to 500 rpm. Specifically, the mixing in step (A) can be performed at a rotation speed of 200 rpm or more, 210 rpm or more, 220 rpm or more, 230 rpm or more, 240 rpm or more, or 250 rpm or more, and 450 rpm or less, 460 rpm or less, 470 rpm or less, 480 rpm or less, 490 rpm or less, or 500 rpm or less. The mixing process in step (A) is a process of remixing the pulverized raw materials, and is preferably performed at a rotation speed lower than that of the pulverization process in step (A). When mixing is performed at a rotation speed within this range, the mixing time can be shortened.

[0059] According to the present invention, the halogen-containing source material may include a chlorine-containing source material and a bromine-containing source material, and the ratio of the number of moles of halogen to the total number of moles of phosphorus, M, and N contained in the reaction mixture may be 1.1 or more and 1.5 or less. Specifically, the ratio of the number of moles of halogen to the total number of moles of phosphorus, M, and N contained in the reaction mixture may be 1.10 or more, 1.15 or more, 1.20 or more, 1.25 or more, 1.30 or more, or 1.40 or more, and may be 1.50 or less. In this case, the degree of delocalization of sulfur ions and halogen ions increases, increasing the amount of vacant space at sites where lithium ions can be located, thereby facilitating lithium ion conduction and providing high ionic conductivity.

[0060] According to the present invention, a non-reactive solvent having a relative polarity to water of 0 to 0.15 may be further mixed during the preparation of the reaction mixture. Here, the non-reactive solvent may be mixed in an amount of 2.5 wt % to 5.0 wt % based on the total amount of the sulfide-based solid electrolyte precursor materials (e.g., (i) lithium-containing precursor materials, (ii) phosphorus-containing precursor materials, (iii) sulfur-containing precursor materials, and optionally, (iv) one or more selected from halogen-containing precursor materials, M-containing precursor materials (M is one or more selected from Si and Ge), and N-containing precursor materials (N is one or more selected from Sn, Sb, Al, Ga, Zn, Zr, In, and Cu)). That is, step (A) may be a step of preparing a reaction mixture by mixing a small amount of the sulfide-based solid electrolyte precursor materials with a non-reactive solvent.

[0061] The sulfide-based solid electrolyte raw materials (e.g., (i) lithium-containing raw materials, (ii) phosphorus-containing raw materials, (iii) sulfur-containing raw materials, and optionally (iv) halogen-containing raw materials, M-containing raw materials (M is at least one selected from Si and Ge)) are highly reactive to moisture, and if exposed to the atmosphere during the production process of a sulfide-based solid electrolyte, they may generate hydrogen sulfide, a harmful gas. The method for producing a sulfide-based solid electrolyte according to the present invention can prevent the raw materials from being exposed to the atmosphere by further mixing the non-reactive solvent.

[0062] The non-reactive solvent may have a relative polarity to water of 0 to 0.15, specifically, 0 or more and 0.13 or less, 0.135 or less, 0.14 or less, 0.145 or less, or 0.15 or less, to prevent the raw material from being exposed to the atmosphere and not to chemically affect the raw material. On the other hand, if the non-reactive solvent has a relative polarity to water of more than 0.15, a side reaction may occur between the solvent and the raw material.

[0063] The non-reactive solvent may be, for example, one or more selected from xylene, benzene, toluene, pentane, hexane, cyclohexane, and heptane, but is not limited thereto.

[0064] According to the present invention, the non-reactive solvent may be mixed with the sulfide-based solid electrolyte raw materials in an amount of 2.5 wt % to 5.0 wt % based on the total amount of the raw materials. Specifically, the non-reactive solvent may be mixed with the sulfide-based solid electrolyte raw materials in an amount of 2.5 wt % or more, 2.6 wt % or more, 2.7 wt % or more, 2.8 wt % or more, 2.9 wt % or more, or 3.0 wt % or more based on the total amount of the raw materials, and may be mixed with the sulfide-based solid electrolyte raw materials in an amount of 4.0 wt % or less, 4.1 wt % or less, 4.2 wt % or less, 4.3 wt % or less, 4.4 wt % or less, 4.5 wt % or less, 4.6 wt % or less, 4.7 wt % or less, 4.8 wt % or less, 4.9 wt % or less, or 5.0 wt % or less. This not only prevents the raw materials from being exposed to the atmosphere, but also prevents the raw materials from becoming solidified during the process of manufacturing the sulfide-based solid electrolyte. Meanwhile, it is preferable that the solid electrolyte has low electronic conductivity and high ionic conductivity. However, if the non-reactive solvent is mixed in an amount exceeding 5.0 wt % based on the total amount of the raw materials, the amount of residual carbon generated from the non-reactive solvent increases, and the residual carbon increases the electronic conductivity of the solid electrolyte after the drying and firing processes, which may cause problems in the function of the solid electrolyte, which should only perform ionic conduction.

[0065] In the present invention, as described above, the addition and mixing of a small amount of a non-reactive solvent can efficiently suppress the sticking phenomenon, thereby improving the ionic conductivity of the solid electrolyte produced.

[0066] The reaction mixture prepared in step (A) may be a powder-type reaction mixture in which the raw materials and the non-reactive solvent are uniformly mixed. Although the reaction mixture contains the non-reactive solvent, it may be in a trace amount, so the reaction mixture may be in a powder-type rather than a slurry-type. Therefore, the mixing in step (A) can be considered as a dry mixing rather than a wet mixing.

[0067] Before processing the reaction mixture into pellets, the powdered reaction mixture can be dried. This is a process for removing non-reactive solvents remaining in the homogeneously mixed reaction mixture, and can be performed by vacuum drying, thermal drying, or thermal drying under vacuum conditions at room temperature to 200°C for 1 minute to 10 hours. Specifically, vacuum drying can be performed in a vacuum oven at 80°C for 1 hour.

[0068] (B) Step Step (B) is a step of compressing the reaction mixture into pellets. For example, the reaction mixture can be compressed into pellets using a press. In this case, the raw materials contained in the reaction mixture become denser, increasing the contact area between particles, which has the advantage of improving the reactivity between the raw materials.

[0069] According to the present invention, the compressing in step (B) may be performed at a pressure of 50 MPa to 400 MPa. Specifically, the compressing may be performed under a pressure of 50 MPa or more, 55 MPa or more, 60 MPa or more, 65 MPa or more, 70 MPa or more, 75 MPa or more, 80 MPa or more, 85 MPa or more, 90 MPa or more, 95 MPa or more, or 100 MPa or more, and 200 MPa or less, 210 MPa or less, 220 MPa or less, 230 MPa or less, 240 MPa or less, 250 MPa or less, 260 MPa or less, 270 MPa or less, 280 MPa or less, 290 MPa or less, 300 MPa or less, 310 MPa or less, 320 MPa or less, 330 MPa or less, 340 MPa or less, 350 MPa or less, 360 MPa or less, 370 MPa or less, 380 MPa or less, 390 MPa or less, or 400 MPa or less. In this case, the pellet shape is well maintained even after the pellet is removed from the mold, and a more uniform result can be obtained.

[0070] (C) Step The step (C) is a step of calcining the reaction mixture in pellet form.

[0071] According to the present invention, the calcination may be performed under an inert atmosphere to prevent side reactions with oxygen and moisture, for example, under an argon atmosphere, a nitrogen atmosphere, or a helium atmosphere.

[0072] According to the present invention, the calcination may be carried out at a temperature of 350° C. to 600° C. More specifically, the calcination temperature may be 350° C. or higher, 360° C. or higher, 370° C. or higher, 380° C. or higher, 390° C. or higher, 400° C. or higher, 410° C. or higher, 420° C. or higher, 430° C. or higher, 440° C. or higher, or 450° C. or higher, and may be 550° C. or lower, 560° C. or lower, 570° C. or lower, 580° C. or lower, 590° C. or lower, or 600° C. or lower. When the calcination temperature is within the above range, an argyrodite-type crystal structure may be formed.

[0073] The temperature maintenance time for the calcination step may be 1 hour to 24 hours, in which case the reaction energy is sufficient to reduce the content of impurities, prevent partial decomposition of the argyrodite-type structure crystal phase at high temperatures, and prevent the particle size of the sulfide-based solid electrolyte powder from becoming excessively large.

[0074] On the other hand, when the reaction mixture contains an M-containing raw material and an N-containing raw material, the calcination temperature may be preferably 400° C. or more, 405° C. or more, 410° C. or more, 415° C. or more, or 420° C. or more, and 480° C. or less, 485° C. or less, 490° C. or less, 495° C. or less, or 500° C. When P-site ions are doped into the argyrodite composition, the calcination temperature can be affected, and within this range, impurity formation can be further reduced, and the resulting solid electrolyte can have excellent performance, such as ionic conductivity.

[0075] (D) Step The method for producing a sulfide-based solid electrolyte according to the present invention may further include the step (D) of pulverizing the fired product.

[0076] Step (D) is a step of controlling particle size by pulverizing the fired product obtained in step (C). The fired pellets can be pulverized by hand grinding in a mortar (mortar pulverization) or by using a planetary ball mill.

[0077] According to the present invention, the pulverization in step (D) may be ball mill pulverization using two or more types of balls with different diameters. When two or more types of balls with different diameters are used, all particles can be uniformly pulverized into fine powder. The material of the balls may be the same as that of the ball mill container, such as zirconia, stainless steel, tungsten carbide, silicon nitride, etc.

[0078] According to the present invention, when the pulverization in step (D) is performed using two or more balls with different diameters, the diameter of the balls may be 1 mm, 3 mm, or 5 mm. The energy applied to the particles is determined depending on the diameter of the balls, and when the diameter of the balls used in the pulverization in step (D) is 1 mm, 3 mm, or 5 mm, the particles can be pulverized uniformly. That is, balls with a relatively large diameter can pulverize large particles with relatively strong energy, and balls with a relatively small diameter can further reduce the particle size of the raw material.

[0079] For example, the pulverization in step (D) may be performed using two or more types of zirconia balls having different diameters. More specifically, the pulverization in step (D) may be performed using zirconia balls having a diameter of 1 mm and zirconia balls having a diameter of 3 mm, and the average particle size (D 50 ) can be carried out so that it is 1.0 μm to 5.0 μm.

[0080] According to the present invention, the pulverization in step (D) can be performed at a rotation speed of 100 rpm to 500 rpm. Specifically, the pulverization in step (D) can be performed at a rotation speed of 100 rpm or more, 110 rpm or more, 120 rpm or more, 130 rpm or more, 140 rpm or more, 150 rpm or more, 160 rpm or more, 170 rpm or more, 180 rpm or more, 190 rpm or more, or 200 rpm or more, and 400 rpm or less, 410 rpm or less, 420 rpm or less, 430 rpm or less, 440 rpm or less, 450 rpm or less, 460 rpm or less, 470 rpm or less, 480 rpm or less, 490 rpm or less, or 500 rpm or less. In this case, the pulverization energy can be appropriately adjusted, which not only allows for the production of a solid electrolyte having a desired particle size but also prevents decomposition of the solid electrolyte.

[0081] According to the present invention, the resulting sulfide-based solid electrolyte may have an argyrodite-type crystal structure, which provides high ionic conductivity and low reactivity with a lithium anode. The sulfide-based solid electrolyte having an argyrodite-type crystal structure means that the sulfide-based solid electrolyte has at least a crystalline phase with an argyrodite-type structure as a major phase. Here, the major phase refers to the phase that accounts for the largest proportion of all crystalline phases constituting the sulfide solid electrolyte. Therefore, the content of the crystalline phase with an argyrodite-type structure in the sulfide-based solid electrolyte may be preferably 90 wt % or more, more preferably 92 wt % or more, 95 wt % or more, or 97 wt % or more, based on the total crystalline phases constituting the sulfide-based solid electrolyte.

[0082] In addition, according to the present invention, the sulfide-based solid electrolyte thus prepared may have a composition represented by the following Chemical Formula 1:

[0083] [Chemical formula 1] Li 7-(x+y)+((a×(5-p))+(b×(5-q))) P 1-(a+b) M a N b S 6-(x+y) Cl x Br y

[0084] In the above Chemical Formula 1, M is at least one selected from Si and Ge, N is one or more selected from Sn, Sb, Al, Ga, Zn, Zr, In and Cu, p is the oxidation number of M, q is the oxidation number of N, 0.1≦x≦1.4, 0.1≦y≦1.4, 1.1 <x+y≦1.5、0≦a≦0.5、0≦b≦0.2である。

[0085] Sulfide solid electrolyte The present invention provides a sulfide-based solid electrolyte having a composition represented by the following Chemical Formula 1 and a total impurity content of 3 wt % or less. The sulfide-based solid electrolyte according to the present invention can be produced by the above-mentioned method for producing a sulfide-based solid electrolyte, thereby reducing the total impurity content.

[0086] [Chemical formula 1] Li 7-(x+y)+((a×(5-p))+(b×(5-q))) P 1-(a+b) M a N b S 6-(x+y) Cl x Br y

[0087] In the above Chemical Formula 1, M is at least one selected from Si and Ge, N is one or more selected from Sn, Sb, Al, Ga, Zn, Zr, In and Cu, p is the oxidation number of M, q is the oxidation number of N, 0.1≦x≦1.4, 0.1≦y≦1.4, 1.1 <x+y≦1.5、0≦a≦0.5、0≦b≦0.2である。

[0088] According to the present invention, the sulfide-based solid electrolyte may have an argyrodite-type crystal structure, which is advantageous in terms of high ionic conductivity, contact stability with lithium, and reproducibility of synthesis.

[0089] According to the present invention, the impurities include both unreacted materials and by-reacted materials during the preparation of a sulfide-based solid electrolyte, and may be, for example, LiS, LiCl, LiBr, and LiSiS. That is, the total content of the impurities may be the total content of LiS, LiCl, LiBr, and LiSiS remaining in the sulfide-based solid electrolyte. The content of the impurities may be obtained by analyzing XRD data of the sulfide-based solid electrolyte powder using a Rietveld refinement program, but is not limited thereto.

[0090] When the sulfide-based solid electrolyte according to the present invention has the composition represented by Chemical Formula 1, the distribution of Li is affected by Cl and Br, which have high entropy, and ionic conductivity is increased.

[0091] According to the present invention, when a sulfide-based solid electrolyte is doped with M, i.e., when a in Formula 1 is greater than 0, the amount of Li present in the solid electrolyte increases, which leads to an expansion of the microstructure and an increase in asymmetry, resulting in improved ionic conductivity. Also, when a sulfide-based solid electrolyte is doped with N, i.e., when b in Formula 1 is greater than 0, stronger bonds with S are formed, which can reduce the loss of S due to moisture, structural collapse, and the resulting degradation of performance and stability.

[0092] According to the present invention, x can be 0.10 or more, 0.15 or more, 0.20 or more, 0.25 or more, 0.30 or more, 0.35 or more, or 0.40 or more, and can be 1.0 or less, 1.05 or less, 1.10 or less, 1.15 or less, 1.20 or less, 1.25 or less, 1.30 or less, 1.35 or less, or 1.40 or less.

[0093] According to the present invention, y can be 0.1 or more, 0.15 or more, 0.20 or more, 0.25 or more, 0.30 or more, 0.35 or more, 0.40 or more, 0.45 or more, or 0.50 or more, and can be 1.0 or less, 1.05 or less, 1.10 or less, 1.15 or less, 1.20 or less, 1.25 or less, 1.30 or less, 1.35 or less, or 1.40 or less.

[0094] According to the present invention, x+y can be 1.10 or more, 1.15 or more, 1.20 or more, 1.25 or more, 1.30 or more, 1.35 or more, or 1.40 or more, and can be 1.50 or less.

[0095] According to the present invention, the a can be 0 or more, and can be 0.20 or less, 0.25 or less, 0.30 or less, 0.35 or less, 0.40 or less, 0.45 or less, or 0.50 or less.

[0096] According to the present invention, the b can be 0 or more, and can be 0.05 or less, 0.10 or less, 0.15 or less, or 0.20 or less.

[0097] According to the present invention, the above-mentioned Chemical Formula 1 may be the following Chemical Formula 2 or the following Chemical Formula 3:

[0098] [Chemical formula 2] Li 7-(x2+y2) PS 6-(x2+y2) Cl x2 Br y2

[0099] In the above Chemical Formula 2, 0.1≦x2≦1.4, 0.1≦y2≦1.4, 1.1 <x2+y2≦1.5である。

[0100] [Chemical formula 3] Li 7-(x3+y3)+((a3×(5-p’))+(b3×(5-q'))) P 1-(a3+b3) M a3 N b3 S 6-(x3+y3) Cl x3 Br y3

[0101] In the above Chemical Formula 1, M is at least one selected from Si and Ge, N is one or more selected from Sn, Sb, Al, Ga, Zn, Zr, In and Cu, p' is the oxidation number of M, q' is the oxidation number of N, 0.1≦x3≦1.4, 0.1≦y3≦1.4, 1.1 <x3+y3≦1.5、0<a3≦0.5、0<b3≦0.2である。

[0102] According to the present invention, x2 and x3 can each independently be 0.10 or more, 0.15 or more, 0.20 or more, 0.25 or more, 0.30 or more, 0.35 or more, or 0.40 or more, and can be 1.0 or less, 1.05 or less, 1.10 or less, 1.15 or less, 1.20 or less, 1.25 or less, 1.30 or less, 1.35 or less, or 1.40 or less.

[0103] According to the present invention, y2 and y can each independently be 0.1 or more, 0.15 or more, 0.20 or more, 0.25 or more, 0.30 or more, 0.35 or more, 0.40 or more, 0.45 or more, or 0.50 or more, and can be 1.0 or less, 1.05 or less, 1.10 or less, 1.15 or less, 1.20 or less, 1.25 or less, 1.30 or less, 1.35 or less, or 1.40 or less.

[0104] According to the present invention, x2+y2 and x3+y3 can each independently be 1.10 or more, 1.15 or more, 1.20 or more, 1.25 or more, 1.30 or more, 1.35 or more, or 1.40 or more, and can be 1.50 or less.

[0105] According to the present invention, a3 can be greater than 0, 0.05 or greater, 0.10 or greater, or 0.15 or greater, and can be 0.25 or less, 0.30 or less, 0.35 or less, 0.40 or less, 0.45 or less, or 0.50 or less.

[0106] According to the present invention, b3 can be greater than 0, 0.01 or greater, 0.02 or greater, or 0.03 or greater, and can be 0.07 or less, 0.08 or less, 0.09 or less, 0.10 or less, 0.15 or less, or 0.20 or less.

[0107] The present invention provides a sulfide-based solid electrolyte having a composition represented by the following Chemical Formula 1 and a total impurity content of 3 wt % or less. The sulfide-based solid electrolyte according to the present invention can be prepared by the above-mentioned method for preparing a sulfide-based solid electrolyte, thereby enabling the total impurity content to be low.

[0108] When the sulfide-based solid electrolyte according to the present invention has a composition represented by Chemical Formula 2, the total content of impurities may be 3 wt% or less, specifically 2 wt% or less. When the sulfide-based solid electrolyte according to the present invention has a composition represented by Chemical Formula 3, the total content of impurities may be 3 wt% or less.

[0109] According to the present invention, the sulfide-based solid electrolyte may have an ionic conductivity of 4.0 mS / cm or more. Specifically, the ionic conductivity of the sulfide-based solid electrolyte may be 4.0 mS / cm or more, 4.1 mS / cm or more, 4.2 mS / cm or more, 4.3 mS / cm or more, 4.4 mS / cm or more, 4.5 mS / cm or more, 4.6 mS / cm or more, 4.7 mS / cm or more, 4.8 mS / cm or more, 4.9 mS / cm or more, 5.0 mS / cm or more, 5.1 mS / cm or more, 5.2 mS / cm or more, 5.3 mS / cm or more, 5.4 mS / cm or more, 5.5 mS / cm or more, 5.6 mS / cm or more, 5.7 mS / cm or more, 5.8 mS / cm or more, 5.9 mS / cm or more, or 6.0 mS / cm or more. The ionic conductivity is determined by the average particle size (D 50 ) is 1.0 μm to 5.0 μm. The higher the ionic conductivity, the better, but the upper limit of the ionic conductivity of the sulfide-based solid electrolyte according to the present invention may be 8.0 mS / cm or less, 8.5 mS / cm or less, 9.0 mS / cm or less, 9.5 mS / cm or less, or 10.0 mS / cm or less.

[0110] When the sulfide-based solid electrolyte according to the present invention has a composition represented by Chemical Formula 2, the ionic conductivity of the solid electrolyte may be 4.0 mS / cm or more, specifically 5.0 mS / cm or more, or 6.0 mS / cm or more. When the sulfide-based solid electrolyte according to the present invention has a composition represented by Chemical Formula 3, the ionic conductivity of the solid electrolyte may be 4.0 mS / cm or more, specifically 5.0 mS / cm or more, 6.0 mS / cm or more, or 6.5 mS / cm or more.

[0111] According to the present invention, the sulfide-based solid electrolyte has an electronic conductivity of 1.0×10 -9 mS / cm ~ 1.0 × 10 -4 The electronic conductivity of the sulfide-based solid electrolyte can be specifically 1.0×10 -9 mS / cm or more, 0.5×10 -8 mS / cm or more, 1.0×10 -8 mS / cm or more, 0.5×10 -7 mS / cm or more, 1.0×10 -7 mS / cm or more, 2.0×10 -7 mS / cm or greater, or 3.0 x 10 -7 mS / cm or more, and -5 mS / cm or less, 8.0×10 -5 mS / cm or less, 8.5×10 -5 mS / cm or less, 9.0×10 -5 mS / cm or less, 9.5×10 -5 mS / cm or less, or 1.0 x 10 -4 When the electronic conductivity of the sulfide-based solid electrolyte is within this range, the solid electrolyte layer blocks the movement of electrons and allows only the movement of lithium ions, thereby properly fulfilling the role of the solid electrolyte.

[0112] According to the present invention, the sulfide-based solid electrolyte has an average particle size (D 50 ) is 1.0 μm to 5.0 μm, specifically 1.0 μm or more, 1.1 μm or more, 1.2 μm or more, 1.3 μm or more, 1.4 μm or more, 1.5 μm or more, 1.6 μm or more, 1.7 μm or more, 1.8 μm or more, 1.9 μm or more, 2.0 μm or more, 2.1 μm or more, 2.2 μm or more, 2.3 μm or more, 2.4 μm or more, or 2.5 μm or more The average particle size (D) of the sulfide-based solid electrolyte may be 3.5 μm or less, 3.6 μm or less, 3.7 μm or less, 3.8 μm or less, 3.9 μm or less, 4.0 μm or less, 4.1 μm or less, 4.2 μm or less, 4.3 μm or less, 4.4 μm or less, 4.5 μm or less, 4.6 μm or less, 4.7 μm or less, 4.8 μm or less, 4.9 μm or less, or 5.0 μm or less. 50) is within the above range, when a solid electrolyte is used to form a film, a uniform film can be formed, and the film resistance can be at a level sufficient to drive an all-solid-state battery.

[0113] All solid state battery The present invention provides an all-solid-state battery containing the sulfide-based solid electrolyte.

[0114] According to one embodiment of the present invention, the all-solid-state battery includes a positive electrode including a positive electrode active material, a negative electrode including a negative electrode active material, and a solid electrolyte layer including a sulfide-based solid electrolyte disposed between the positive electrode and the negative electrode.

[0115] The all-solid-state battery according to the present invention has little decrease in ionic conductivity due to moisture, and can have excellent initial efficiency, life characteristics, and output characteristics.

[0116] The all-solid-state battery of the present invention can be manufactured by a conventional method known in the art, for example, by stacking a positive electrode and a negative electrode so that a solid electrolyte layer is present between them and applying pressure.

[0117] (1) Positive electrode The positive electrode may be prepared by coating a positive electrode current collector with a positive electrode slurry containing a positive electrode active material, a binder, a conductive material, and a solvent.

[0118] The positive electrode current collector may be any material that does not cause chemical changes in the battery and has conductivity, and may be, for example, stainless steel, aluminum, nickel, titanium, calcined carbon, or aluminum or stainless steel surface-treated with carbon, nickel, titanium, silver, etc. Furthermore, the surface may be provided with fine irregularities to enhance the bonding strength of the positive electrode active material, and may be used in various forms such as a film, sheet, foil, mesh, porous material, foam, or nonwoven fabric.

[0119] The positive electrode active material can include a lithium metal oxide containing lithium and one or more metals such as cobalt, manganese, nickel, or aluminum, as a compound capable of reversible intercalation and deintercalation of lithium. More specifically, the lithium metal oxide can be a lithium-manganese-based oxide (e.g., LiMnO2, LiMn2O4, etc.), a lithium-cobalt-based oxide (e.g., LiCoO2, etc.), a lithium-nickel-based oxide (e.g., LiNiO2, etc.), a lithium-nickel-manganese-based oxide (e.g., LiNi 1-Y Mn Y O2 (where 0 < Y < 1), LiMn 2-z Ni z O4 (where 0 < Z < 2), etc.), a lithium-nickel-cobalt-based oxide (e.g., LiNi 1-Y1 Co Y1 O2 (where 0 < Y1 < 1), etc.), a lithium-manganese-cobalt-based oxide (e.g., LiCo 1-Y2 Mn Y2 O2 (where 0 < Y2 < 1), LiMn 2-z1 Co z1 O4 (where 0 < Z1 < 2), etc.), a lithium-nickel-manganese-cobalt-based oxide (e.g., Li(Ni p Co q Mn r1 )O2 (where 0 < p < 1, 0 < q < 1, 0 < r1 < 1, p + q + r1 = 1) or Li(Ni p1 Co q1 Mn r2 )O4 (where 0 < p1 < 2, 0 < q1 < 2, 0 < r2 < 2, p1 + q1 + r2 = 2), etc.), or a lithium-nickel-cobalt-transition metal (M) oxide (e.g., Li(Ni p2 Co q2 Mn r3 M S2)O2 (where M is selected from the group consisting of Al, Fe, V, Cr, Ti, Ta, Mg, and Mo, and p2, q2, r3, and s2 are the atomic fractions of independent elements, 0 < p2 < 1, 0 < q2 < 1, 0 < r3 < 1, 0 < s2 < 1, and p2 + q2 + r3 + s2 = 1), etc.) etc. can be mentioned, and one or more of these compounds can be included.

[0120] Among them, in terms of being able to enhance the capacity characteristics and stability of the battery, the lithium metal oxide is LiCoO2, LiMnO2, LiNiO2, lithium nickel manganese cobalt oxide (for example, Li(Ni 1 / 3 Mn 1 / 3 Co 1 / 3 )O2, Li(Ni 0.6 Mn 0.2 Co 0.2 )O2, Li(Ni 0.5 Mn 0.3 Co 0.2 )O2, Li(Ni 0.7 Mn 0.15 Co 0.15 )O2, and Li(Ni 0.8 Mn 0.1 Co 0.1 )O2, etc.), or lithium nickel cobalt aluminum oxide (for example, Li(Ni 0.8 Co 0.15 Al 0.05 , etc.), and considering the significance of the improvement effect by controlling the types and content ratios of the constituent elements forming the lithium composite metal oxide, the lithium composite metal oxide can be Li(Ni 0.6 Mn 0.2 Co 0.2 )O2, Li(Ni 0.5 Mn 0.3 Co 0.2 )O2, Li(Ni 0.7 Mn 0.15 Co 0.15 )O2, and Li(Ni 0.8 Mn 0.1 Co 0.1 )O2, etc., and one or more of these mixtures can be used.

[0121] The positive electrode active material may be included in an amount of 60 wt % or more, 70 wt % or more, 80 wt % or more, or 99 wt % or less, or 98 wt % or less, based on the total weight of solids other than the solvent in the positive electrode slurry.

[0122] The binder is a component that helps bind the conductive material, active material, and current collector together. Examples of such binders include polyvinylidene fluoride, polyvinyl alcohol, carboxymethyl cellulose, starch, hydroxypropyl cellulose, regenerated cellulose, polyvinylpyrrolidone, tetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene monomer, sulfonated ethylene-propylene-diene monomer, styrene-butadiene rubber, fluororubber, and various copolymers thereof.

[0123] Typically, the binder can be contained in an amount of 1 wt % to 20 wt %, preferably 1 wt % to 15 wt %, and more preferably 1 wt % to 10 wt %, based on the total weight of solids other than the solvent in the positive electrode slurry.

[0124] The conductive material is a component for further improving the conductivity of the positive electrode active material.

[0125] The conductive material is not particularly limited as long as it does not cause a chemical change in the battery and has conductivity. For example, carbon-based materials such as graphite; carbon black, acetylene black, ketjen black, channel black, furnace black, lamp black, and thermal black; conductive fibers such as carbon fiber and metal fiber; metal powders such as carbon fluoride, aluminum, and nickel powder; conductive whiskers such as zinc oxide and potassium titanate; conductive metal oxides such as titanium oxide; and conductive materials such as polyphenylene derivatives may be used.

[0126] Typically, the conductive material may be contained in an amount of 1 wt % or more, 20 wt % or less, 15 wt % or less, or 10 wt % or less based on the total weight of solids other than the solvent in the positive electrode slurry.

[0127] The solvent may include an organic solvent such as N-methyl-2-pyrrolidone (NMP) and may be used in an amount that provides a desired viscosity when the positive electrode active material, and optionally, a binder and a conductive material, are included. For example, the solvent may be included so that the concentration of the solids, including the positive electrode active material, and optionally, a binder and a conductive material, is 50 wt % or more, 60 wt % or more, 70 wt % or more, 95 wt % or less, or 90 wt % to 85 wt %.

[0128] (2) Negative electrode The negative electrode can be prepared by, for example, coating a negative electrode current collector with a negative electrode slurry containing a negative electrode active material, a binder, a conductive material, and a solvent, or a graphite electrode made of carbon (C) or a metal itself can be used as the negative electrode.

[0129] For example, when the negative electrode is manufactured by coating the negative electrode slurry onto the negative electrode current collector, the negative electrode current collector typically has a thickness of 3 to 500 μm. Such a negative electrode current collector is not particularly limited as long as it does not cause chemical changes in the battery and has high conductivity. Examples of such a negative electrode current collector include copper, stainless steel, aluminum, nickel, titanium, calcined carbon, copper or stainless steel surfaces treated with carbon, nickel, titanium, silver, etc., and aluminum-cadmium alloys. Furthermore, similar to the positive electrode current collector, the surface can be formed with fine irregularities to enhance the binding strength of the negative electrode active material, and the negative electrode current collector can be used in various forms, such as a film, sheet, foil, mesh, porous material, foam, or nonwoven fabric.

[0130] The negative electrode active material may be natural graphite, artificial graphite, carbonaceous material, lithium-containing titanium composite oxide (LTO), Si, SiO x, Sn, Li, Zn, Mg, Cd, Ce, Ni or Fe (Me); alloys composed of the above metals (Me); oxides of the above metals (Me) (MeO x and composites of the metals (Me) with carbon. Specific examples of the negative electrode active material include silicon (Si), silicon oxide (SiO x Silicon-based negative electrode active materials, such as silicon dioxide, silicon nitride, silicon carbide ...

[0131] The negative electrode active material may be included in an amount of 60 wt % or more, 70 wt % or more, 80 wt % or more, 99 wt % or less, or 98 wt % or less based on the total weight of solids other than the solvent in the negative electrode slurry.

[0132] The binder is a component that helps bind the conductive material, active material, and current collector together. Examples of such binders include polyvinylidene fluoride, polyvinyl alcohol, carboxymethyl cellulose, starch, hydroxypropyl cellulose, regenerated cellulose, polyvinylpyrrolidone, tetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene monomer, sulfonated ethylene-propylene-diene monomer, styrene-butadiene rubber, fluororubber, and various copolymers thereof.

[0133] Typically, the binder may be included in an amount of 1 wt % or more, 20 wt % or less, 15 wt % or less, or 10 wt % or less based on the total weight of solids other than the solvent in the negative electrode slurry.

[0134] The conductive material is a component for further improving the conductivity of the negative electrode active material. The conductive material is not particularly limited as long as it does not cause chemical changes in the battery and has conductivity, and examples thereof include graphite such as natural graphite and artificial graphite; carbon black such as acetylene black, ketjen black, channel black, furnace black, lamp black, and thermal black; conductive fibers such as carbon fiber and metal fiber; metal powders such as carbon fluoride, aluminum, and nickel powder; conductive whiskers such as zinc oxide and potassium titanate; conductive metal oxides such as titanium oxide; and conductive materials such as polyphenylene derivatives.

[0135] The conductive material may be contained in an amount of 1 wt % or more, 20 wt % or less, 15 wt % or less, or 10 wt % or less based on the total weight of solids other than the solvent in the negative electrode slurry.

[0136] The solvent may include water or an organic solvent such as NMP (N-methyl-2-pyrrolidone), and may be used in an amount that provides a desired viscosity when the negative electrode active material, and optionally, the binder and conductive material, are included. For example, the solvent may be included so that the concentration of the solids, including the negative electrode active material, and optionally, the binder and conductive material, is 50 wt % or more, 60 wt % or more, 70 wt % or more, 95 wt % or less, or 90 wt % to 85 wt %.

[0137] When a metal is used as the anode, the anode can be fabricated by physically bonding, rolling, or depositing a metal thin film on the anode current collector or the metal thin film itself. The deposition method can be electrolytic deposition or chemical vapor deposition.

[0138] For example, the metal thin film itself or the metal bonded / rolled / deposited on the negative electrode current collector may include one metal or an alloy of two metals selected from the group consisting of lithium (Li), nickel (Ni), tin (Sn), copper (Cu), and indium (In).

[0139] (3) Solid electrolyte layer The solid electrolyte layer may further contain a binder in addition to the solid electrolyte according to the present invention.

[0140] The binder is a component that helps bind the conductive material, active material, and current collector together. Examples of such binders include polyvinylidene fluoride, polyvinyl alcohol, carboxymethyl cellulose, starch, hydroxypropyl cellulose, regenerated cellulose, polyvinylpyrrolidone, tetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene monomer, sulfonated ethylene-propylene-diene monomer, styrene-butadiene rubber, fluororubber, and various copolymers thereof.

[0141] The binder may be included in an amount of 1 wt % or more, 20 wt % or less, 15 wt % or less, or 10 wt % or less based on the total weight of the solid electrolyte layer.

[0142] The present invention provides a battery module including the all-solid-state battery as a unit cell, and a battery pack including the same. The battery module and battery pack include the secondary battery having high capacity, excellent rate-limiting characteristics, and excellent cycle characteristics, and can be used as a power source for medium- to large-sized devices selected from the group consisting of electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, and power storage systems.

[0143] While the present invention may be embodied in various different forms, it is to be understood that the invention is not limited to the specific embodiments set forth herein, and that the invention may be embodied in various different forms without departing from the spirit or scope of the present invention.

[0144] Examples and Comparative Examples Example 1 Li2S powder, P2S5 powder, LiCl powder, and LiBr powder were each prepared. Using a planetary ball mill (FRITSCH, Pulverisette 7 Planetary Micro Mill - Premium line), Li2S powder, P2S5 powder, LiCl powder, and LiBr powder were each pre-milled. The pre-milling was carried out by placing 1 mm diameter zirconia balls and 3 mm diameter zirconia balls in a 1:1 weight ratio into the zirconia container of the planetary ball mill, and then adding each powder to a ball-to-powder ratio (BPR) of 6, at 550 rpm for 2 hours.

[0145] Then, 3 mm diameter zirconia balls and 5 mm diameter zirconia balls were placed in a zirconia container of a planetary ball mill (FRITSCH, PULVERISETTE 7 Planetary Micro Mill - Premium line) in a weight ratio of 1:1, and the previously milled Li2S powder, P2S5 powder, LiCl powder, and LiBr powder were mixed to form a solid electrolyte with a composition of Li 5.5 PS 4.5 ClBr 0.5 The BPR was added in a ratio of 6, and xylene was added in an amount of 2.5 wt% based on the total amount of LiS powder, P2S5 powder, LiCl powder, and LiBr powder, and then the mixture was mixed at 300 rpm for 4 hours to prepare a reaction mixture.

[0146] The reaction mixture was then placed in a vacuum oven and vacuum dried at 80° C. for 4 hours, and then 5 g of the powder was compressed at 200 MPa using a mold and press machine with a diameter of 25 mm to form a pellet.

[0147] The pellet-shaped reaction mixture was then fired at 550°C under an argon gas atmosphere to produce a fired product. The fired product was then mortar-ground for 30 minutes using an agate mortar and pestle, and then pulverized using a planetary ball mill (FRITSCH, PULVERISETTE 7 Planetary Micro Mill - Premium line) to produce a sulfide-based solid electrolyte (composition: Li5.5 PS 4.5 ClBr 0.5 The crushing was carried out by adding 3 mm diameter zirconia balls and 5 mm diameter zirconia balls in a weight ratio of 1:1 to a zirconia container of a planetary ball mill, adding the fired product that had been crushed in a mortar to a BPR of 6, crushing the product at 250 rpm for 10 minutes followed by a 20 minute break, and repeating this cycle 20 times.

[0148] Example 2 A sulfide-based solid electrolyte (composition: Li) was prepared in the same manner as in Example 1, except that the pre-grinding was performed at a rotation speed of 650 rpm instead of 550 rpm. 5.5 PS 4.5 ClBr 0.5 ) was manufactured.

[0149] Example 3 A sulfide-based solid electrolyte (composition: Li) was prepared in the same manner as in Example 1, except that xylene was added in an amount of 3.5 wt % instead of 2.5 wt % based on the total amount of LiS powder, P2S5 powder, LiCl powder, and LiBr powder. 5.5 PS 4.5 ClBr 0.5 ) was manufactured.

[0150] Example 4 A sulfide-based solid electrolyte (composition: Li) was prepared in the same manner as in Example 1, except that xylene was added in an amount of 6.0 wt % instead of 2.5 wt % based on the total amount of LiS powder, P2S5 powder, LiCl powder, and LiBr powder. 5.5 PS 4.5 ClBr 0.5 ) was manufactured.

[0151] Example 5 Li2S powder, P2S5 powder, LiCl powder, LiBr powder, SiS2 powder, and SnS2 powder were prepared. Using a planetary ball mill (FRITSCH, Pulverisette 7 Planetary Micro Mill - Premium line), Li2S powder, P2S5 powder, LiCl powder, LiBr powder, SiS2 powder, and SnS2 powder were pre-milled. The pre-milling was carried out by placing 1 mm diameter zirconia balls and 3 mm diameter zirconia balls in a 1:1 weight ratio into the zirconia container of the planetary ball mill, and then adding each powder to achieve a BPR of 6. The pre-milling was carried out at 550 rpm for 2 hours.

[0152] Then, 3 mm diameter zirconia balls and 5 mm diameter zirconia balls were placed in a zirconia container of a planetary ball mill (FRITSCH, PULVERISETTE 7 Planetary Micro Mill - Premium line) in a weight ratio of 1:1, and the previously milled Li2S powder, P2S5 powder, LiCl powder, LiBr powder, SiS2 powder, and SnS2 powder were mixed to form a solid electrolyte having a composition of Li 5.85 Si 0.2 Sn 0.05 P 0.75 S 4.6 Cl 0.4 The mixture was charged in a ratio of 1:1, so that the BPR was 6, and xylene was added in an amount of 2.5 wt% based on the total amount of LiS powder, P2S5 powder, LiCl powder, LiBr powder, SiS2 powder, and SnS2 powder, and then mixed at 300 rpm for 4 hours to prepare a reaction mixture.

[0153] The reaction mixture was then placed in a vacuum oven and vacuum dried at 80° C. for 4 hours, and then 5 g of the powder was compressed at 100 MPa using a mold and press machine with a diameter of 25 mm to form a pellet.

[0154] The pellet-shaped reaction mixture was then fired at 450°C under an argon gas atmosphere to produce a fired product. The fired product was then mortar-ground for 30 minutes using an agate mortar and pestle, and then pulverized using a planetary ball mill (FRITSCH, PULVERISETTE 7 Planetary Micro Mill - Premium line) to produce a sulfide-based solid electrolyte (composition: Li 5.85 Si 0.2 Sn 0.05 P 0.75 S 4.6 Cl 0.4 Br) was produced. Here, the pulverization was carried out by adding 3 mm diameter zirconia balls and 5 mm diameter zirconia balls in a weight ratio of 1:1 to a zirconia container of a planetary ball mill, adding the fired product that had been mortar-pulverized so that the BPR was 6, and then pulverizing at 250 rpm for 10 minutes followed by a 20-minute break, which was repeated 20 times.

[0155] Example 6 A sulfide-based solid electrolyte (composition: Li) was prepared in the same manner as in Example 1, except that the pre-grinding was performed at a rotation speed of 650 rpm instead of 550 rpm. 5.85 Si 0.2 Sn 0.05 P 0.75 S 4.6 Cl 0.4 Br) was produced.

[0156] Example 7 A sulfide-based solid electrolyte (composition: Li) was prepared in the same manner as in Example 1, except that xylene was added in an amount of 3.5 wt % instead of 2.5 wt % based on the total amount of LiS powder, P2S5 powder, LiCl powder, LiBr powder, SiS2 powder, and SnS2 powder. 5.85 Si 0.2 Sn 0.05 P 0.75 S 4.6 Cl 0.4 Br) was produced.

[0157] Example 8 A sulfide-based solid electrolyte (composition: Li) was prepared in the same manner as in Example 1, except that xylene was added in an amount of 6.0 wt % instead of 2.5 wt % based on the total amount of LiS powder, P2S5 powder, LiCl powder, LiBr powder, SiS2 powder, and SnS2 powder. 5.85 Si 0.2 Sn 0.05 P 0.75 S 4.6 Cl 0.4 Br) was produced.

[0158] Example 9 Li2S powder, P2S5 powder, and LiCl powder were prepared. Each of the Li2S powder, P2S5 powder, and LiCl powder was pre-milled using a planetary ball mill (FRITSCH, PULVERISETTE 7 Planetary Micro Mill - Premium line). The pre-milling was carried out by placing 1 mm diameter zirconia balls and 3 mm diameter zirconia balls in a 1:1 weight ratio into the zirconia container of the planetary ball mill, and then adding each powder to achieve a BPR of 6. The pre-milling was carried out at 550 rpm for 2 hours.

[0159] Then, 3 mm diameter zirconia balls and 5 mm diameter zirconia balls were added to a zirconia container of a planetary ball mill (FRITSCH, PULVERISETTE 7 Planetary Micro Mill - Premium line) in a weight ratio of 1:1, and the previously milled LiS powder, P2S5 powder, and LiCl powder were added in a ratio such that the resulting solid electrolyte had a composition of Li6PS5Cl and the BPR was 6. Xylene was then added in an amount of 2.5 wt % based on the total amount of the Li2S powder, P2S5 powder, and LiCl powder, and the mixture was mixed at 300 rpm for 4 hours to prepare a reaction mixture.

[0160] The reaction mixture was then placed in a vacuum oven and vacuum dried at 80° C. for 4 hours, and then 5 g of the powder was compressed at 200 MPa using a mold and press machine with a diameter of 25 mm to form a pellet.

[0161] The pellet-form reaction mixture was then fired at 550°C under an argon gas atmosphere to produce a fired product. The fired product was then mortar-ground using an agate mortar and pestle for 30 minutes and then pulverized using a planetary ball mill (FRITSCH, PULVERISETTE 7 Planetary Micro Mill - Premium line) to produce a sulfide-based solid electrolyte (composition: Li6PS5Cl). The pulverization was carried out by placing 3 mm diameter zirconia balls and 5 mm diameter zirconia balls in a 1:1 weight ratio into the zirconia container of the planetary ball mill, and adding the mortar-ground fired product to achieve a BPR of 6. The mortar-ground product was then milled at 250 rpm for 10 minutes followed by a 20-minute break, and this cycle was repeated 20 times.

[0162] Comparative Example 1 Li2S powder, P2S5 powder, LiCl powder, and LiBr powder were prepared. Zirconia balls with a diameter of 3 mm were placed in the zirconia container of a planetary ball mill (FRITSCH, PULVERISETTE 7 Planetary Micro Mill - Premium line) to mix the Li2S powder, P2S5 powder, LiCl powder, and LiBr powder until the resulting solid electrolyte had a composition of Li 5.5 PS 4.5 ClBr 0.5 The mixture was mixed at 300 rpm for 4 hours to prepare a reaction mixture.

[0163] The reaction mixture was then fired at 550°C under an argon gas atmosphere to produce a fired product. The fired product was then mortar-ground for 30 minutes using an agate mortar and pestle, and then pulverized using a planetary ball mill (FRITSCH, PULVERISETTE 7 Planetary Micro Mill - Premium line) to produce a sulfide-based solid electrolyte (composition: Li 5.5 PS 4.5 ClBr 0.5The crushing was carried out by adding 3 mm diameter zirconia balls and 5 mm diameter zirconia balls in a weight ratio of 1:1 to a zirconia container of a planetary ball mill, adding the fired product that had been crushed in a mortar to a BPR of 6, crushing the product at 250 rpm for 10 minutes followed by a 20 minute break, and repeating this cycle 20 times.

[0164] Comparative Example 2 Li2S powder, P2S5 powder, LiCl powder, and LiBr powder were prepared. 3 mm diameter zirconia balls and 5 mm diameter zirconia balls were placed in a zirconia container of a planetary ball mill (FRITSCH, PULVERISETTE 7 Planetary Micro Mill - Premium line) at a weight ratio of 1:1. The resulting solid electrolyte had a composition of Li2S powder, P2S5 powder, LiCl powder, and LiBr powder. 5.5 PS 4.5 ClBr 0.5 The BPR was added in a ratio of 6, and xylene was added in an amount of 2.5 wt% based on the total amount of LiS powder, P2S5 powder, LiCl powder, and LiBr powder, and then the mixture was mixed at 300 rpm for 4 hours to prepare a reaction mixture.

[0165] The reaction mixture was then placed in a vacuum oven and vacuum dried at 80° C. for 4 hours, and then 5 g of the powder was compressed at 200 MPa using a mold and press machine with a diameter of 25 mm to form a pellet.

[0166] The pellet-shaped reaction mixture was then fired at 550°C under an argon gas atmosphere to produce a fired product. The fired product was then mortar-ground for 30 minutes using an agate mortar and pestle, and then pulverized using a planetary ball mill (FRITSCH, PULVERISETTE 7 Planetary Micro Mill - Premium line) to produce a sulfide-based solid electrolyte (composition: Li 5.5 PS 4.5 ClBr 0.5The crushing was carried out by adding 3 mm diameter zirconia balls and 5 mm diameter zirconia balls in a weight ratio of 1:1 to a zirconia container of a planetary ball mill, adding the fired product that had been crushed in a mortar to a BPR of 6, crushing the product at 250 rpm for 10 minutes followed by a 20 minute break, and repeating this cycle 20 times.

[0167] Comparative Example 3 Li2S powder, P2S5 powder, LiCl powder, and LiBr powder were each prepared. Using a planetary ball mill (FRITSCH, Pulverisette 7 Planetary Micro Mill - Premium line), Li2S powder, P2S5 powder, LiCl powder, and LiBr powder were each pre-milled. The pre-milling was carried out by placing 1 mm diameter zirconia balls and 3 mm diameter zirconia balls in a 1:1 weight ratio into the zirconia container of the planetary ball mill, and then adding each powder to a ball-to-powder ratio (BPR) of 6, at 550 rpm for 2 hours.

[0168] Then, 3 mm diameter zirconia balls and 5 mm diameter zirconia balls were placed in a zirconia container of a planetary ball mill (FRITSCH, PULVERISETTE 7 Planetary Micro Mill - Premium line) in a weight ratio of 1:1, and the previously milled Li2S powder, P2S5 powder, LiCl powder, and LiBr powder were mixed to form a solid electrolyte with a composition of Li 5.5 PS 4.5 ClBr 0.5 The BPR was added in a ratio of 6, and xylene was added in an amount of 2.5 wt% based on the total amount of LiS powder, P2S5 powder, LiCl powder, and LiBr powder, and then the mixture was mixed at 300 rpm for 4 hours to prepare a reaction mixture.

[0169] The reaction mixture was then fired at 550°C under an argon gas atmosphere to produce a fired product. The fired product was then mortar-ground for 30 minutes using an agate mortar and pestle, and then pulverized using a planetary ball mill (FRITSCH, PULVERISETTE 7 Planetary Micro Mill - Premium line) to produce a sulfide-based solid electrolyte (composition: Li 5.5 PS 4.5 ClBr 0.5 The crushing was carried out by adding 3 mm diameter zirconia balls and 5 mm diameter zirconia balls in a weight ratio of 1:1 to a zirconia container of a planetary ball mill, adding the fired product that had been crushed in a mortar to a BPR of 6, crushing the product at 250 rpm for 10 minutes followed by a 20 minute break, and repeating this cycle 20 times.

[0170] Comparative Example 4 Li2S powder, P2S5 powder, LiCl powder, LiBr powder, SiS2 powder, and SnS2 powder were prepared. Zirconia balls with a diameter of 3 mm were placed in the zirconia container of a planetary ball mill (FRITSCH, PULVERISETTE 7 Planetary Micro Mill - Premium line) to mix the Li2S powder, P2S5 powder, LiCl powder, LiBr powder, SiS2 powder, and SnS2 powder. The resulting solid electrolyte had a composition of Li 5.85 Si 0.2 Sn 0.05 P 0.75 S 4.6 Cl 0.4 Br 4 and BPR 6, and then mixed at 300 rpm for 4 hours to prepare a reaction mixture.

[0171] The reaction mixture was then fired at 550°C under an argon gas atmosphere to produce a fired product. The fired product was then mortar-ground for 30 minutes using an agate mortar and pestle, and then pulverized using a planetary ball mill (FRITSCH, PULVERISETTE 7 Planetary Micro Mill - Premium line) to produce a sulfide-based solid electrolyte (composition: Li5.85 Si 0.2 Sn 0.05 P 0.75 S 4.6 Cl 0.4 Br) was produced. Here, the pulverization was carried out by adding 3 mm diameter zirconia balls and 5 mm diameter zirconia balls in a weight ratio of 1:1 to a zirconia container of a planetary ball mill, adding the fired product that had been mortar-pulverized so that the BPR was 6, and then pulverizing at 250 rpm for 10 minutes followed by a 20-minute break, which was repeated 20 times.

[0172] Comparative Example 5 Li2S powder, P2S5 powder, LiCl powder, LiBr powder, SiS2 powder, and SnS2 powder were prepared. 3 mm diameter zirconia balls and 5 mm diameter zirconia balls were placed in a zirconia container of a planetary ball mill (FRITSCH, PULVERISETTE 7 Planetary Micro Mill - Premium line) at a weight ratio of 1:1. The resulting solid electrolyte had a composition of Li2S powder, P2S5 powder, LiCl powder, LiBr powder, SiS2 powder, and SnS2 powder. 5.85 Si 0.2 Sn 0.05 P 0.75 S 4.6 Cl 0.4 The mixture was charged in a ratio of 1:1, so that the BPR was 6, and xylene was added in an amount of 2.5 wt% based on the total amount of LiS powder, P2S5 powder, LiCl powder, LiBr powder, SiS2 powder, and SnS2 powder, and then mixed at 300 rpm for 4 hours to prepare a reaction mixture.

[0173] The reaction mixture was then placed in a vacuum oven and vacuum dried at 80° C. for 4 hours, and then 5 g of the powder was compressed at 100 MPa using a mold and press machine with a diameter of 25 mm to form a pellet.

[0174] The pellet-shaped reaction mixture was then fired at 550°C under an argon gas atmosphere to produce a fired product. The fired product was then mortar-ground for 30 minutes using an agate mortar and pestle, and then pulverized using a planetary ball mill (FRITSCH, PULVERISETTE 7 Planetary Micro Mill - Premium line) to produce a sulfide-based solid electrolyte (composition: Li 5.5 PS 4.5 ClBr 0.5 The crushing was carried out by adding 3 mm diameter zirconia balls and 5 mm diameter zirconia balls in a weight ratio of 1:1 to a zirconia container of a planetary ball mill, adding the fired product that had been crushed in a mortar to a BPR of 6, crushing the product at 250 rpm for 10 minutes followed by a 20 minute break, and repeating this cycle 20 times.

[0175] Comparative Example 6 Li2S powder, P2S5 powder, LiCl powder, LiBr powder, SiS2 powder, and SnS2 powder were prepared. Using a planetary ball mill (FRITSCH, Pulverisette 7 Planetary Micro Mill - Premium line), Li2S powder, P2S5 powder, LiCl powder, LiBr powder, SiS2 powder, and SnS2 powder were pre-milled. The pre-milling was carried out by placing 1 mm diameter zirconia balls and 3 mm diameter zirconia balls in a 1:1 weight ratio into the zirconia container of the planetary ball mill, and then adding each powder to achieve a BPR of 6. The pre-milling was carried out at 550 rpm for 2 hours.

[0176] Then, 3 mm diameter zirconia balls and 5 mm diameter zirconia balls were placed in a zirconia container of a planetary ball mill (FRITSCH, PULVERISETTE 7 Planetary Micro Mill - Premium line) in a weight ratio of 1:1, and the previously milled Li2S powder, P2S5 powder, LiCl powder, LiBr powder, SiS2 powder, and SnS2 powder were mixed to form a solid electrolyte having a composition of Li 5.85 Si 0.2 Sn 0.05 P0.75 S 4.6 Cl 0.4 The mixture was charged in a ratio of 1:1, so that the BPR was 6, and xylene was added in an amount of 2.5 wt% based on the total amount of LiS powder, P2S5 powder, LiCl powder, LiBr powder, SiS2 powder, and SnS2 powder, and then mixed at 300 rpm for 4 hours to prepare a reaction mixture.

[0177] The reaction mixture was then fired at 450°C under an argon gas atmosphere to produce a fired product. The fired product was then mortar-ground for 30 minutes using an agate mortar and pestle, and then pulverized using a planetary ball mill (FRITSCH, PULVERISETTE 7 Planetary Micro Mill - Premium line) to produce a sulfide-based solid electrolyte (composition: Li 5.85 Si 0.2 Sn 0.05 P 0.75 S 4.6 Cl 0.4 Br) was produced. Here, the pulverization was carried out by adding 3 mm diameter zirconia balls and 5 mm diameter zirconia balls in a weight ratio of 1:1 to a zirconia container equipped with a planetary ball mill, adding the fired product that had been mortar-pulverized so that the BPR was 6, and then pulverizing at 250 rpm for 10 minutes followed by a 20-minute rest period, which was repeated 20 times.

[0178] Comparative Example 7 Li2S powder, P2S5 powder, and LiCl powder were prepared. Zirconia balls with a diameter of 3 mm were placed in the zirconia container of a planetary ball mill (FRITSCH, PULVERISETTE 7 Planetary Micro Mill - Premium line). Li2S powder, P2S5 powder, and LiCl powder were added in a ratio such that the resulting solid electrolyte composition would be Li6PS5Cl and the BPR would be 6. The mixture was then mixed at 300 rpm for 4 hours to produce a reaction mixture.

[0179] The reaction mixture was then fired at 550°C under an argon gas atmosphere to produce a fired product. The fired product was then mortar-ground for 30 minutes using an agate mortar and pestle, and then pulverized using a planetary ball mill (FRITSCH, PULVERISETTE 7 Planetary Micro Mill - Premium line) to produce a sulfide-based solid electrolyte (composition: Li6PS5Cl). The pulverization was carried out by placing 3 mm diameter zirconia balls and 5 mm diameter zirconia balls in a 1:1 weight ratio into the zirconia container of the planetary ball mill, and adding the mortar-ground fired product to achieve a BPR of 6. The mortar-ground product was then milled at 250 rpm for 10 minutes, followed by a 20-minute break, for a total of 20 cycles.

[0180] Table 1 below shows the compositions of the solid electrolytes prepared in the examples and comparative examples, as well as whether the raw materials were pulverized before mixing and whether the reaction mixture was processed into pellets.

[0181] [Table 1]

[0182] Experimental Example Experimental example 1: Impurity evaluation The impurity ratios of the solid electrolyte powder were calculated using XRD measurements and Rietveld refinement analysis. The XRD equipment used was a Bruker D8 Endeavor, Cu Kα radiation, 1.5406 Å wavelength. The measurement conditions were non-atmospheric exposure, a scan rate of 2° / min, and a theta angle of 10–90°. The impurities (Li2S, LiCl, LiBr, and Li4SiS4) were identified using the TOPAS Rietveld refinement program, and the impurity ratios were quantified. The results are shown in Table 2.

[0183] Experimental Example 2: Evaluation of ionic conductivity 150 mg of each of the solid electrolyte powders prepared in the Examples and Comparative Examples was placed in a 13 mm diameter SUS mold. The mold, along with the insulating PEEK, was attached to a press, and a potentiostat (SP-200, manufactured by Biologics) was connected to the SUS mold. After applying a pressure of 370 MPa to sufficiently densify the electrolyte structure, the pressure was gradually reduced to maintain 100 MPa, and AC impedance measurements were performed at frequencies from 0.1 Hz to 7 MHz. The ionic conductivity was calculated from the measured resistance using a Nyquist plot, and is shown in Table 2 below. All measurements were performed in a dry room at a temperature of 25°C and a relative humidity of 0.7%.

[0184] Experimental Example 3: Evaluation of electronic conductivity 150 mg of each of the solid electrolytes prepared in the Examples and Comparative Examples was placed in a mold having a diameter of 13 mm and pressurized at 370 MPa to form a solid electrolyte layer. The pressure was then reduced to 100 MPa, and a DC voltage of 1 V was applied using a potentiostat (Biologics Corp., SP-200) at room temperature (25°C) for 6 hours. After saturation, the current was measured to measure the electrical conductivity. The results are shown in Table 2 below.

[0185] Experimental Example 4 20 mg of the solid electrolyte powder prepared in the examples and comparative examples was dispersed in 5 ml of xylene, and then introduced into a laser diffraction particle size measuring device (Malvern Panalytical, Mastersizer 3000) to measure the average particle size (D 50 ) were measured, and the results are shown in Table 2 below.

[0186] [Table 2]

[0187] Referring to Tables 1 and 2, when preparing sulfide-based solid electrolytes with the same composition, it can be seen that the content of impurities is significantly reduced when raw materials are first crushed and mixed to prepare a reaction mixture, which is then compressed into pellets and sintered, thereby improving ionic and electronic conductivity.

[0188] As a result, it was found that the method for manufacturing a sulfide-based solid electrolyte according to the present invention can prevent the adhesion of raw materials and can also improve the reactivity of the raw materials. Furthermore, it was found that the sulfide-based solid electrolyte manufactured by the method for manufacturing a sulfide-based solid electrolyte according to the present invention contains almost no impurities and has excellent physical properties such as ionic conductivity and electronic conductivity.

Claims

1. (A) grinding sulfide-based solid electrolyte raw materials and then mixing them to prepare a reaction mixture; (B) compressing the reaction mixture into pellet form; (C) firing the reaction mixture in pellet form to produce a fired product.

2. 2. The method for producing a sulfide-based solid electrolyte according to claim 1, wherein the sulfide-based solid electrolyte raw material comprises one or more selected from (i) a lithium-containing raw material, (ii) a phosphorus-containing raw material, (iii) a sulfur-containing raw material, and, optionally, (iv) a halogen-containing raw material, an M-containing raw material (M is one or more selected from Si and Ge), and an N-containing raw material (N is one or more selected from Sn, Sb, Al, Ga, Zn, Zr, In, and Cu).

3. 2. The method for producing a sulfide-based solid electrolyte according to claim 1, wherein the pulverization in step (A) is ball mill pulverization using two or more types of balls having different diameters.

4. 4. The method for producing a sulfide-based solid electrolyte according to claim 3, wherein the diameter of the balls used in the pulverization in step (A) is 1 mm, 3 mm, or 5 mm.

5. 2. The method for producing a sulfide-based solid electrolyte according to claim 1, wherein the pulverization in step (A) is carried out at a rotation speed of 500 rpm to 800 rpm.

6. 2. The method for producing a sulfide-based solid electrolyte according to claim 1, wherein the mixing in step (A) is ball mill mixing using two or more types of balls having different diameters.

7. 7. The method for producing a sulfide-based solid electrolyte according to claim 6, wherein the diameter of the balls during mixing in step (A) is 1 mm, 3 mm, 5 mm, or 10 mm.

8. 2. The method for producing a sulfide-based solid electrolyte according to claim 1, wherein the mixing in step (A) is carried out at a rotation speed of 200 rpm to 500 rpm.

9. the (iv) halogen-containing source material includes a chlorine-containing source material and a bromine-containing source material; 3. The method for producing a sulfide-based solid electrolyte according to claim 2, wherein the ratio of the number of moles of halogen to the total number of moles of phosphorus, M, and N contained in the reaction mixture is 1.1 or more and 1.5 or less.

10. 2. The method for producing a sulfide-based solid electrolyte according to claim 1, wherein a non-reactive solvent having a relative polarity to water of 0 to 0.15 is further mixed during the preparation of the reaction mixture.

11. The method for producing a sulfide-based solid electrolyte according to claim 10, wherein the non-reactive solvent is mixed in an amount of 2.5 wt % to 5.0 wt % based on the total amount of the sulfide-based solid electrolyte raw materials.

12. 2. The method for producing a sulfide-based solid electrolyte according to claim 1, wherein the compression in step (B) is performed at a pressure of 50 MPa to 400 MPa.

13. The method for producing a sulfide-based solid electrolyte according to claim 1, wherein the firing is carried out at a temperature of 350°C to 600°C.

14. The method for producing a sulfide-based solid electrolyte according to claim 1 , further comprising the step (D) of pulverizing the fired product.

15. 15. The method for producing a sulfide-based solid electrolyte according to claim 14, wherein the pulverization in step (D) comprises pulverizing the fired product in a mortar and then pulverizing the fired product in a ball mill using two or more types of balls having different diameters.

16. The method for producing a sulfide-based solid electrolyte according to claim 15, wherein the diameter of the balls used in the pulverization in step (D) is 1 mm, 3 mm, 5 mm, or 10 mm.

17. The method for producing a sulfide-based solid electrolyte according to claim 14, wherein the pulverization in step (D) is carried out at a rotation speed of 100 rpm to 500 rpm.

18. It has a composition represented by the following chemical formula 1: A sulfide-based solid electrolyte having a total impurity content of 3% by weight or less. [Chemical formula 1] Li ７－（ｘ＋ｙ）＋（（ａ×（５－ｐ））＋（ｂ×（５－ｑ））） P １－（ａ＋ｂ） M ａ N ｂ S ６－（ｘ＋ｙ） Cl ｘ Br ｙ In the above Chemical Formula 1, M is at least one selected from Si and Ge; N is one or more selected from Sn, Sb, Al, Ga, Zn, Zr, In, and Cu; p is the oxidation number of M, q is the oxidation number of N, 0.1≦x≦1.4, 0.1≦y≦1.4, 1.1<x+y≦1.5, 0≦a≦0.5, and 0≦b≦0.

2.

19. The sulfide-based solid electrolyte according to claim 18, wherein the sulfide-based solid electrolyte has an ionic conductivity of 4.0 mS / cm or more.

20. The sulfide-based solid electrolyte has an electronic conductivity of 1.0×10 －９ mS / cm~1.0×10 －４ The sulfide-based solid electrolyte according to claim 18, wherein the conductivity is mS / cm.

21. The sulfide-based solid electrolyte has an average particle size (D ５０ 19. The sulfide-based solid electrolyte according to claim 18, wherein the average particle size is 1.0 μm to 5.0 μm.

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