Sulfide-based solid electrolyte and all-solid-state battery containing the same

Abstract

The present invention relates to a sulfide-based solid electrolyte and an all-solid-state battery containing the same. More specifically, in a sulfide-based solid electrolyte containing lithium (Li), phosphorus (P), sulfur (S), and chlorine (Cl), the phosphorus (P) site is replaced with a different element, and when two or more elements selected from the group consisting of Ge, Sn, Sb, and Si are replaced in equal proportions, the ionic conductivity in the sulfide-based solid electrolyte can be improved.

Description

Technical Field

[0001] Cross - reference to Related Applications This application claims the benefit of priority based on Korean Patent Application No. 10 - 2024 - 0013764 filed on January 30, 2024, and all the contents disclosed in the literature of the Korean patent application are included as part of this specification.

[0002] Technical Field The present invention relates to a sulfide - based solid electrolyte and an all - solid - state battery including the same.

Background Art

[0003] From the viewpoints of battery capacity, safety, output, large - scale, and ultra - small - scale, etc., currently, various batteries that can overcome the limitations of lithium secondary batteries are being studied.

[0004] Typically, compared with lithium secondary batteries, metal - air batteries that have a very large theoretical capacity in terms of capacity, all - solid - state batteries that have no risk of explosion in terms of safety, supercapacitors in terms of output, NaS batteries or RFB (redox flow batteries) in terms of large - scale, and thin - film batteries in terms of ultra - small - scale, etc. are continuously being studied in the academic and industrial fields.

[0005] An all - solid - state battery means a battery in which the liquid electrolyte used in a conventional lithium secondary battery is replaced with a solid electrolyte. Since no flammable solvent is used in the battery and ignition or explosion due to decomposition reactions of conventional electrolytes does not occur at all, safety can be significantly improved. Also, since lithium metal or a lithium alloy can be used as the negative electrode material, there is an advantage that the energy density with respect to the mass and volume of the battery can be epochally improved.

[0006] However, in all-solid-state batteries, the solid electrolyte is applied in a small particle size state, which increases the number of interfaces and thus the resistance, ultimately potentially reducing the performance, lifespan, and stability of the all-solid-state battery and degrading cell performance.

[0007] This degradation of cell performance due to increased interfacial resistance can be offset by increasing the ionic conductivity of the solid electrolyte.

[0008] Therefore, development of solid electrolytes with high ionic conductivity is necessary for use in all-solid-state batteries. [Prior art documents] [Patent Documents]

[0009] [Patent Document 1] Japanese Patent Publication No. 2015-22015 [Overview of the Initiative] [Problems that the invention aims to solve]

[0010] As a result of conducting multifaceted research to solve the aforementioned problems, the inventors have confirmed that when two or more elements selected from the group consisting of Ge, Sn, Sb, and Si are substituted at the P site in a sulfide-based solid electrolyte containing lithium (Li), phosphorus (P), sulfur (S), and chlorine (Cl), the ionic conductivity of the sulfide-based solid electrolyte is improved.

[0011] Therefore, an object of the present invention is to provide a sulfide-based solid electrolyte with improved ionic conductivity.

[0012] Another object of the present invention is to provide an all-solid-state battery containing a sulfide-based solid electrolyte with improved ionic conductivity. [Means for solving the problem]

[0013] To achieve the above object, the present invention provides a sulfide-based solid electrolyte containing lithium (Li), phosphorus (P), sulfur (S), chlorine (Cl), and M, wherein M is contained in a form substituted at the site of phosphorus (P) and contains two or more selected from the group consisting of Ge, Sn, Sb, and Si.

[0014] In one embodiment of the present invention, the sulfide-based solid electrolyte is represented by the following Chemical Formula 1: <Chemical Formula 1> Li (6-x) P y M (1-y) S (5-x) Cl (1+x) where x satisfies 0 < x < 0.6 and y satisfies 0.9 ≤ y < 1, where M is M1 a M2 b (0 < a + b ≤ 0.1, a + b = 1 - y), M1 a M2 b M3 c (0 < a + b + c ≤ 0.1, a + b + c = 1 - y) or M1 a M2 b M3 c M4 d (0 < a + b + c + d ≤ 0.1, a + b + c + d = 1 - y), and M1, M2, M3, and M4 are different elements selected from the group consisting of Ge, Si, Sb, and Sn, respectively.

[0015] In one embodiment of the present invention, the two or more elements substituted at the site of phosphorus (P) are substituted in equal ratios, and M is M1 a M2 b (0 < a + b ≤ 0.1, a + b = 1 - y, a = b), M1 a M2 b M3 c (0 < a + b + c ≤ 0.1, a + b + c = 1 - y, a = b = c) or M1 a M2 b M3 c M4 dProvided is a sulfide-based solid electrolyte, where (0 < a + b + c + d ≤ 0.1, a + b + c + d = 1 - y, a = b = c = d).

[0016] In one embodiment of the present invention, provided is a sulfide-based solid electrolyte, where the sulfide-based solid electrolyte has an argyrodite-type crystal structure.

[0017] In one embodiment of the present invention, provided is a sulfide-based solid electrolyte, where the ionic conductivity of the sulfide-based solid electrolyte is 4 - 6 mS / cm.

[0018] In one embodiment of the present invention, provided is a sulfide-based solid electrolyte, where the content of impurities in the sulfide-based solid electrolyte is 0% - 5% based on the intensity of the XRD main peak.

[0019] In one embodiment of the present invention, provided is a sulfide-based solid electrolyte, where the impurities include Li2S, LiCl, or compounds thereof.

[0020] The present invention also provides a all-solid-state battery including a positive electrode, a negative electrode, and the sulfide-based solid electrolyte interposed therebetween.

[0021] In one embodiment of the present invention, provided is a all-solid-state battery, where the negative electrode is a lithium negative electrode containing lithium metal.

Advantages of the Invention

[0022] According to the solid electrolyte of the present invention, by substituting two or more elements selected from the group consisting of Ge, Sn, Sb, and Si for a part of the sites of phosphorus (P) contained in the sulfide-based solid electrolyte, the solid solution increasing effect of the substitution elements is improved. As a result, the ionic conductivity of the sulfide-based solid electrolyte is enhanced, and the impurities are reduced.

Modes for Carrying Out the Invention

[0023] Hereinafter, in order to facilitate the understanding of the present invention, the present invention will be described in more detail.

[0024] The terms and words used herein and in the claims shall not be construed to be limited to their ordinary or dictionary meanings, but rather to be construed in a sense and concept consistent with the technical idea of ​​the present invention, based on the principle that an inventor may appropriately define the concept of a term in order to best describe his invention.

[0025] Sulfide solid electrolyte This invention relates to sulfide-based solid electrolytes.

[0026] The sulfide-based solid electrolyte according to the present invention contains lithium (Li), phosphorus (P), sulfur (S), chlorine (Cl), and M, wherein M is included in a form in which it is partially substituted for the site of phosphorus (P), and comprises two or more elements selected from the group consisting of Ge, Sn, Sb, and Si.

[0027] When two or more elements selected from the group consisting of Ge, Sn, Sb, and Si are substituted in the P portion, the disorder within the structure increases, allowing lithium ions to move smoothly and improving the ionic conductivity of the sulfide-based solid electrolyte. Preferably, the two or more elements are substituted in equal proportions.

[0028] If one element is substituted at the P site, that element may precipitate as an impurity in a quantity exceeding the amount that can be substituted within the structure of the sulfide-based solid electrolyte. In this case, by lowering the substitution ratio of the one element and increasing the ratio of substitution with other elements, the ionic conductivity of the sulfide-based solid electrolyte can be improved. For example, if only Sn is substituted as one element at the P site, 0.94 Sn 0.06 Compared to the case where two different elements, Sn and Si, are substituted in equal proportions, P 0.94 Sn 0.03 Si 0.03 In this case, the disorder within the structure increases, which can improve ionic conductivity.

[0029] In one embodiment of the present invention, the sulfide-based solid electrolyte may be represented by the following Chemical Formula 1: <Chemical Formula 1> Li (6-x) P y M (1-y) S (5-x) Cl (1+x) where x satisfies 0 < x < 0.6, y satisfies 0.9 ≤ y < 1, and M is M1 a M2 b (0 < a + b ≤ 0.1, a + b = 1 - y), M1 a M2 b M3 c (0 < a + b + c ≤ 0.1, a + b + c = 1 - y) or M1 a M2 b M3 c M4 d (0 < a + b + c + d ≤ 0.1, a + b + c + d = 1 - y), and M1, M2, M3, and M4 are different elements selected from the group consisting of Ge, Si, Sb, and Sn, respectively.

[0030] For example, the sulfide-based solid electrolyte represented by Chemical Formula 1 may be Li 5.5 P 0.94 Si 0.03 Sn 0.03 S 4.5 Cl 1.5 and may be acceptable.

[0031] In addition, two or more elements substituting the P site may be substituted at the same ratio. If the ratios of two or more elements to be substituted are not the same, impurities may be generated or the ionic conductivity may decrease. For example, in Chemical Formula 1, M is M1 a M2 b (0 < a + b ≤ 0.1, a + b = 1 - y, a = b), M1 a M2 b M3 c (0 < a + b + c ≤ 0.1, a + b + c = 1 - y, a = b = c) or M1 a M2 b M3c M4 d (0 <a+b+c+d≦0.1、a+b+c+d=1-y、a=b=c=d)であってもよい。

[0032] In one embodiment of the present invention, the sulfide-based solid electrolyte may have an argyrodite-type crystal structure. The argyrodite-type crystal structure is obtained by substituting a portion of the substance with chlorine.

[0033] Conventionally, the crystal structure of the aforementioned sulfide-based solid electrolyte is a face-centered cubic lattice (FCC) structure, which causes lithium ions to be trapped within the sulfur atom octahedra during migration. However, by substituting a portion of the material with chlorine, the strength of the electrostatic attraction changes, altering the arrangement of atoms within the structure. This lowers the activation energy, creating new pathways for lithium ion migration and improving ionic conductivity. In the present invention, in addition to such an argyrodite-type crystal structure, the material has a structure in which two or more elements are substituted at the P site, thus reducing the impurity content and further improving ionic conductivity.

[0034] In one embodiment of the present invention, the ionic conductivity of the sulfide-based solid electrolyte may be 4 to 6 mS / cm.

[0035] The aforementioned sulfide-based solid electrolyte can have two or more elements substituted at the P site, thereby generating a disorder in its crystal structure. This facilitates the movement of lithium ions, increases the solid solution ratio of elements, improves ionic conductivity, and consequently reduces impurities.

[0036] In one embodiment of the present invention, the content of impurities in the sulfide-based solid electrolyte may be 0% to 5% based on the intensity of the XRD main peak, and the impurities may include Li2S, LiCl, or compounds thereof. The impurities may be formed when the raw materials of the sulfide-based solid electrolyte cannot be dissolved in the structure and precipitate as impurities, or when these impurities combine to form new forms of impurities.

[0037] Method for producing sulfide-based solid electrolytes The present invention also relates to a method for producing sulfide-based solid electrolytes.

[0038] The method for producing a sulfide-based solid electrolyte according to the present invention includes the steps of (S1) pulverizing a raw material and (S2) heat-treating the powder obtained in step (S1). This can also be called a solid-phase synthesis method.

[0039] The method for producing a sulfide-based solid electrolyte according to the present invention will be described in more detail below, step by step.

[0040] In one embodiment of the present invention, the raw material can be pulverized in step (S1).

[0041] The aforementioned raw material may mean the raw material for each element contained in the sulfide-based solid electrolyte. The aforementioned raw material is not particularly limited as long as it is a substance commonly used in the industry as a raw material for each element. For example, the aforementioned raw material may include the raw material for forming the sulfide-based solid electrolyte and the raw material for the substitution element. The raw material for forming the sulfide-based solid electrolyte includes lithium sulfide (Li2S), phosphorus pentasulfide (P2S5), and lithium chloride (LiCl), and the raw material for the substitution element may include two or more selected from the group consisting of silicon (Si), silicon sulfide (SiS2), tin sulfide (SnS2), germanium sulfide (GeS2), and antimony sulfide (Sb2S5). Alternatively, 0.1 to 0.5 moles of phosphorus pentasulfide (P2S5), 0.5 to 1.5 moles of lithium chloride (LiCl), and 0.01 to 0.1 moles of the raw material for the substitution element may be used per mole of lithium sulfide (Li2S). Specifically, the amount of phosphorus pentasulfide (P2S5) may be 0.1 mole or more, 0.15 mole or more, or 0.2 mole or more, and may be used in amounts of 0.5 mole or less, 0.4 mole or less, or 0.3 mole or less. Furthermore, the amount of lithium chloride (LiCl) may be 0.5 mole or more, 0.6 mole or more, or 0.7 mole or more, and may be used in amounts of 1.5 mole or less, 1.4 mole or less, 1.3 mole or less, 1.2 mole or less, 1.1 mole or less, 1.0 mole or less, 0.9 mole or less, or 0.8 mole or less. Additionally, the raw material for the substitution element may be 0.01 mole or more, 0.02 mole or more, or 0.03 mole or more, and may be used in amounts of 0.1 mole or less, 0.09 mole or less, 0.08 mole or less, 0.07 mole or less, 0.06 mole or less, or 0.05 mole or less.

[0042] Furthermore, the grinding method is not particularly limited as long as it can be carried out in a way that can be used to obtain powder. For example, the grinding method may be milling, hand milling, ball milling, etc.

[0043] In one embodiment of the present invention, in step (S2), the powder obtained in step (S1) can be heat-treated.

[0044] The heat treatment can be carried out under conditions of an inert atmosphere, at a temperature of 400°C to 600°C, and for 10 to 14 hours. The inert atmosphere may mean an atmosphere of nitrogen, helium, argon, or carbon dioxide. The temperature may be 400°C or higher, 450°C or higher, or 500°C or higher, and may be 600°C or lower, 580°C or lower, or 560°C or lower.

[0045] Furthermore, the sulfide-based solid electrolyte according to the present invention can be obtained through steps (S1) and (S2), and the manufacturing process including steps (S1) and (S2) may be carried out in a glove box that is not exposed to moisture and oxygen.

[0046] all solid state battery The present invention also relates to an all-solid-state battery comprising the sulfide-based solid electrolyte.

[0047] The all-solid-state battery according to the present invention comprises a sulfide-based solid electrolyte; a positive electrode formed on one surface of the sulfide-based solid electrolyte; and a negative electrode formed on the other surface of the sulfide-based solid electrolyte.

[0048] In one embodiment of the present invention, the positive electrode may include a positive electrode active material, a conductive material, and a binder.

[0049] In the present invention, the positive electrode included in the all-solid-state battery includes a positive electrode active material layer, and the positive electrode active material layer may be formed on one surface of the positive electrode current collector.

[0050] The positive electrode active material layer comprises a positive electrode active material, a conductive material, and a binder.

[0051] Furthermore, the positive electrode active material is not particularly limited as long as it is a material capable of reversibly intercalating and releasing lithium ions, for example, lithium cobalt oxide (LiCoO2), lithium nickel oxide (LiNiO2), Li[Ni x Co y Mn z M v]O2(In the above formula, M is one or more elements selected from the group consisting of Al, Ga, and In; 0.3≦x<1.0, 0≦y, z≦0.5, 0≦v≦0.1, x+y+z+v=1), Li(Li a M b-a-b’ M' b’ )O 2-c A c Layered compounds such as (in the above formula, 0≦a≦0.2, 0.6≦b≦1, 0≦b'≦0.2, 0≦c≦0.2; M comprises Mn and one or more selected from the group consisting of Ni, Co, Fe, Cr, V, Cu, Zn, and Ti; M' is one or more selected from the group consisting of Al, Mg, and B, and A is one or more selected from the group consisting of P, F, S, and N), or compounds substituted with one or more transition metals; chemical formula Li 1+y Mn 2-y Lithium manganese oxides such as O4 (where y is 0 to 0.33), LiMnO3, LiMn2O3, LiMnO2; lithium copper oxide (Li2CuO2); vanadium oxides such as LiV3O8, LiFe3O4, V2O5, Cu2V2O7; chemical formula LiNi 1-y Lithium nickel oxide of the Ni site type, represented as MyO2 (where M = Co, Mn, Al, Cu, Fe, Mg, B, or Ga, and y is 0.01 to 0.3); chemical formula LiMn 2-y M y Lithium manganese composite oxides represented as O2 (where M is Co, Ni, Fe, Cr, Zn, or Ta, and y is 0.01 to 0.1) or Li2Mn3MO8 (where M is Fe, Co, Ni, Cu, or Zn); LiMn2O4 in which part of the Li in the chemical formula is substituted with alkaline earth metal ions; disulfide compounds; Fe2(MoO4)3, etc. are examples, but are not limited to these.

[0052] Furthermore, the positive electrode active material may be present in an amount of 60 to 80% by weight based on the total weight of the positive electrode active material layer. Specifically, the content of the positive electrode active material may be 60% or more by weight, 65% or more by weight, or 68% or more by weight, and may be 72% or less by weight, 75% or less by weight, or 80% or less by weight. If the content of the positive electrode active material is less than 60% by weight, the battery performance may decrease, and if it exceeds 80% by weight, the mass transfer resistance may increase.

[0053] Furthermore, the conductive material is not particularly limited as long as it prevents side reactions in the internal environment of the all-solid-state battery, does not induce chemical changes in the battery, and has excellent electrical conductivity. Typically, graphite or conductive carbon may be used, for example, graphite such as natural graphite or artificial graphite; carbon black such as carbon black, acetylene black, Ketjen black, Denka black, thermal black, channel black, furnace black, and lamp black; carbon-based materials whose crystalline structure is graphene or graphite; conductive fibers such as carbon fibers and metal fibers; carbon fluoride; metal powders such as aluminum powder and nickel powder; conductive whiskers such as zinc oxide and potassium titanate; conductive oxides such as titanium oxide; and conductive polymers such as polyphenylene derivatives; which may be used alone or in mixtures of two or more, but are not necessarily limited to these. Preferably, the conductive material may also contain vapor-grown carbon fiber (VGCF).

[0054] The conductive material may typically be present in an amount of 1% to 5% by weight based on the total weight of the positive electrode active material layer. Specifically, the content of the conductive material may be 1% or more by weight, 1.5% or more by weight, or 2% or more by weight, or 4% or less by weight, 4.5% or less by weight, or 5% or less by weight. If the content of the conductive material is too low (less than 1% by weight), it may be difficult to expect an improvement in electrical conductivity, or the electrochemical properties of the battery may deteriorate. If it is too high (more than 5% by weight), the amount of positive electrode active material will be relatively small, which may reduce the capacity and energy density. The method of incorporating the conductive material into the positive electrode is not significantly limited, and conventional methods known in the art, such as mixing with the positive electrode active material or coating, may be used.

[0055] Furthermore, the binder contains components that assist in the bonding of the positive electrode active material to conductive materials and to the current collector, such as styrene-butadiene rubber, acrylic styrene-butadiene rubber, acrylonitrile copolymer, acrylonitrile-butadiene rubber, nitrile-butadiene rubber, acrylonitrile-styrene-butadiene copolymer, acrylic rubber, butyl rubber, fluororubber, polytetrafluoroethylene, polyethylene, polypropylene, ethylene / propylene copolymer, polybutadiene, polyethylene oxide, chlorosulfonated polyethylene, polyvinylpyrrolidone, polyvinylpyridine, polyvinyl alcohol, polyvinyl acetate, polyepichlorohydrin, polyphosphazene, The binder may contain one or more selected from the group consisting of polyacrylonitrile, polystyrene, latex, acrylic resin, phenolic resin, epoxy resin, carboxymethylcellulose, hydroxypropylcellulose, cellulose acetate, butyrate cellulose acetate, cellulose propionate acetate, cyanoethylcellulose, cyanoethylsucrose, polyester, polyamide, polyether, polyimide, polycarboxylate, polycarboxylic acid, polyacrylic acid, polyacrylate, lithium polyacrylate, polymethacrylic acid, polymethacrylate, polyacrylamide, polyurethane, polyvinylidene fluoride, and poly(vinylidene fluoride)-hexafluoropropene. Preferably, the binder may contain polytetrafluoroethylene (PTFE).

[0056] Furthermore, the binder may be present in an amount of 0.5% to 4% by weight based on the total weight of the positive electrode active material layer. Specifically, the binder content may be 0.5% or more by weight, 1% or more by weight, or 1.5% or more by weight, or 3% or less by weight, 3.5% or less by weight, or 4% or less by weight. If the binder content is less than 0.5% by weight, the adhesive strength between the positive electrode active material and the positive electrode current collector may decrease. If it exceeds 4% by weight, the adhesive strength will improve, but the content of the positive electrode active material will decrease accordingly, potentially reducing the battery capacity.

[0057] Furthermore, the positive electrode current collector supports the positive electrode active material layer and plays a role in transferring electrons between the external conductor and the positive electrode active material layer.

[0058] The positive electrode current collector is not particularly limited as long as it does not induce chemical changes in the all-solid-state battery and has high electronic conductivity. For example, copper, stainless steel, aluminum, nickel, titanium, palladium, calcined carbon, copper or stainless steel surface-treated with carbon, nickel, silver, etc., or aluminum-cadmium alloy may be used as the positive electrode current collector.

[0059] The positive electrode current collector may have a fine uneven surface or a three-dimensional porous structure to enhance the bonding force with the positive electrode active material layer. As a result, the positive electrode current collector may take various forms such as film, sheet, foil, mesh, net, porous material, foam, or nonwoven fabric.

[0060] The positive electrode described above can be manufactured by conventional methods. Specifically, it can be manufactured by mixing a positive electrode active material, a conductive material, and a binder in an organic solvent phase to produce a composition for forming a positive electrode active material layer, which is then coated onto a positive electrode current collector and dried, and then compression-molded onto the current collector to selectively improve electrode density. In this case, it is preferable to use an organic solvent that can uniformly disperse the positive electrode active material, binder, and conductive material and evaporates easily. Specifically, examples include acetonitrile, methanol, ethanol, tetrahydrofuran, water, and isopropyl alcohol.

[0061] In the present invention, the negative electrode included in the all-solid-state battery includes a negative electrode active material layer, and the negative electrode active material layer may be formed on one surface of the negative electrode current collector.

[0062] The negative electrode active material is lithium (Li +The material may include a substance that can be reversibly intercalated or deintercalated, a substance that can reversibly form a lithium-containing compound by reacting with lithium ions, or a lithium metal or lithium alloy.

[0063] The aforementioned lithium ion (Li + The material that can reversibly insert or remove the lithium ion (Li) may be, for example, crystalline carbon, amorphous carbon, or a mixture thereof. + The substance that can reversibly form a lithium-containing compound by reacting with ) may be, for example, tin oxide, titanium nitrate, or silicon. The lithium alloy may be, for example, an alloy of lithium (Li) and a metal selected from the group consisting of indium (In), sodium (Na), potassium (K), rubidium (Rb), cesium (Cs), francium (Fr), beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), radium (Ra), aluminum (Al), and tin (Sn).

[0064] Preferably, the negative electrode active material may be lithium metal or lithium-indium alloy (Li-In), and more specifically, it may be in the form of lithium metal or lithium in thin film or lithium-indium alloy thin film or powder.

[0065] The negative electrode active material may be present in an amount of 40 to 80% by weight based on the total weight of the negative electrode active material layer. Specifically, the content of the negative electrode active material may be 40% or more by weight, 50% or more by weight, or 70% or less by weight, or 80% or less by weight. If the content of the negative electrode active material is less than 40% by weight, the connectivity between the wet negative electrode active material layer and the dry negative electrode active material layer may be insufficient, and if it exceeds 80% by weight, the mass transfer resistance may increase.

[0066] Furthermore, the binder is as described in detail in the positive electrode active material layer.

[0067] Furthermore, the conductive material is as described in detail in the positive electrode active material layer.

[0068] Furthermore, the negative electrode current collector is not particularly limited as long as it does not induce chemical changes in the battery and is conductive. For example, the negative electrode current collector may be made of copper, stainless steel, aluminum, nickel, titanium, calcined carbon, copper or stainless steel surface-treated with carbon, nickel, titanium, silver, etc., or aluminum-cadmium alloy. Also, similar to the positive electrode current collector, the negative electrode current collector may be made of various forms such as films, sheets, foils, nets, porous materials, foams, or nonwoven fabrics with fine irregularities formed on their surface.

[0069] The method for manufacturing the negative electrode is not particularly limited, and it can be manufactured by forming a negative electrode active material layer on a negative electrode current collector using a layer or film formation method commonly used in the industry. For example, methods such as crimping, coating, and vapor deposition can be used. Furthermore, the negative electrode of the present invention is also included in the case where a metallic lithium thin film is formed on a metal plate by initial charging after the battery has been assembled without a lithium thin film on the negative electrode current collector.

[0070] Battery module The present invention also relates to a battery module including the all-solid-state battery as a unit battery, a battery pack including the battery module, and a device including the battery pack as a power source.

[0071] Specific examples of the aforementioned devices include, but are not limited to, power tools powered by electric motors; electric vehicles including electric vehicles (EVs), hybrid electric vehicles (HEVs), and plug-in hybrid electric vehicles (PHEVs); electric two-wheeled vehicles including electric bicycles (E-bikes) and electric scooters; electric golf carts; and power storage systems.

[0072] The following are preferred embodiments to aid in understanding the present invention. However, these embodiments are merely illustrative of the present invention, and it will be obvious to those skilled in the art that various changes and modifications are possible within the scope of the present invention and the technical concept, and such changes and modifications will naturally fall within the scope of the attached claims.

[0073] Example 1 A solid-phase synthesis method was performed in which the raw materials were hand-milled for 30 minutes in a glove box, and then heat-treated at 520°C for 12 hours under an Ar atmosphere to produce a sulfide-based solid electrolyte. The raw materials used were 2 moles of lithium sulfide (Li2S, Mitsuwa Chemical product), 0.47 moles of phosphorus pentasulfide (P2S5, Aldrich product), 1.5 moles of lithium chloride (LiCl, Aldrich product), 0.03 moles of silicon (Si, Sigma Aldrich product), and 0.03 moles of tin sulfide (SnS2, Kojundo product).

[0074] Comparative Example 1 Li is used in the same manner as in Example 1, except that the substitution element is not substituted at the P site. 5.5 PS 4.5 Cl 1.5 The following was manufactured: 2 moles of lithium sulfide (Li2S, Mitsuwa Chemical product), 0.5 moles of phosphorus pentasulfide (P2S5, Aldrich product), and 1.5 moles of lithium chloride (LiCl, Aldrich product) were used as raw materials.

[0075] Comparative Example 2 Li was manufactured in the same manner as in Example 1, except that only one substitution element, namely Sn, was substituted at the P site. 5.5 P 0.94 Sn 0.06 S 4.5 Cl 1.5The following was manufactured: 2 moles of lithium sulfide (Li2S, Mitsuwa Chemical product), 0.47 moles of phosphorus pentasulfide (P2S5, Aldrich product), 1.5 moles of lithium chloride (LiCl, Aldrich product), and 0.06 moles of tin sulfide (SnS2, Kojundo product).

[0076] Experimental Example 1: Measurement of Ionic Conductivity Electrochemical impedance spectroscopy (EIS) analysis was performed to measure the ionic conductivity of the sulfide-based solid electrolytes prepared in the examples and comparative examples.

[0077] An electrode cell was fabricated for EIS analysis. The electrode cell was manufactured using a 13 mm diameter electrode, with 200 mg of the sulfide-based solid electrolyte placed in the electrode and pressurized at a pressure of 360 MPa.

[0078] Using an electrochemical impedance spectrometer (EIS, VMP300Bio Logic), resistance was measured at 25°C under AC 0.1V and frequencies from 1Hz to 0.1MHz. The ionic conductivity of the sulfide-based solid electrolyte was then calculated using Equation 1 below.

[0079] [Formula 1]

number

[0080] In the above formula 1, σ i R is the ionic conductivity (mS / cm) of the sulfide-based solid electrolyte, R is the resistance (Ω) of the sulfide-based solid electrolyte measured by the electrochemical impedance spectrometer, L is the thickness (μm) of the sulfide-based solid electrolyte, and A is the area (cm²) of the sulfide-based solid electrolyte. 2 ) means.

[0081] Table 1 below shows the composition and measured ionic conductivity of the sulfide-based solid electrolytes produced in the examples and comparative examples. The compositions of the sulfide-based solid electrolytes listed in Table 1 below represent the composition of each element in Chemical Formula 1.

[0082] [Table 1]

[0083] Referring to Table 1 above, it can be seen that Example 1, in which part of the P portion is replaced with two types of substitution elements, exhibits the best ionic conductivity.

[0084] Although the present invention has been described in part by limited embodiments and drawings, it is understood that the present invention is not limited thereto, and that various modifications and variations are possible within the equivalent scope of the technical concept of the present invention and the claims described below by persons with ordinary skill in the art to which the present invention pertains.

Claims

1. It contains lithium (Li), phosphorus (P), sulfur (S), chlorine (Cl), and M. The aforementioned M is included in a form in which it is substituted for the phosphorus (P) site, A sulfide-based solid electrolyte represented by the following chemical formula 1: <Chemical formula 1> Li (6-x) PyM (1-y) S (5-x) Cl (1+x) The above x is 0 < x < 0.6, and the above y is 0.9 ≤ y < 1, The above M is M1 a M2 b (0<a+b≦0.1, a+b=1-y), M1 a M2 b M3 c (0<a+b+c≦0.1, a+b+c=1-y), or M1 a M2 b M3 c M4 d (0<a+b+c+d≦0.1, a+b+c+d=1-y), The elements M1, M2, M3, and M4 are each different elements selected from the group consisting of Ge, Si, Sb, and Sn.

2. Two or more elements substituted at the site of the phosphorus (P) are substituted at the same ratio, and M is M1 ａ M2 ｂ (0 < a + b ≤ 0.1, a + b = 1 - y, a = b), M1 ａ M2 ｂ M3 ｃ (0 < a + b + c ≤ 0.1, a + b + c = 1 - y, a = b = c) or M1 ａ M2 ｂ M3 ｃ M4 ｄ (0 < a + b + c + d ≤ 0.1, a + b + c + d = 1 - y, a = b = c = d), the sulfide-based solid electrolyte according to claim 1.

3. The sulfide-based solid electrolyte according to claim 1, wherein the sulfide-based solid electrolyte has an argyrodite-type crystal structure.

4. The sulfide-based solid electrolyte according to claim 1, wherein the ionic conductivity of the sulfide-based solid electrolyte is 4 to 6 mS / cm.

5. The sulfide-based solid electrolyte according to claim 1, wherein the impurity content in the sulfide-based solid electrolyte is 0% to 5% based on the intensity of the XRD main peak.

6. The aforementioned impurity is Li ２ A sulfide-based solid electrolyte according to claim 5, comprising S, LiCl, or compounds thereof.

7. An all-solid-state battery comprising a positive electrode, a negative electrode, and a sulfide-based solid electrolyte interposed between them, as described in claim 1.

8. The all-solid-state battery according to claim 7, wherein the negative electrode is a lithium negative electrode containing lithium metal.

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