Solid electrolyte and all-solid-state battery comprising same

Abstract

The present invention relates to a sulfide-based solid electrolyte which contains lithium (Li), phosphorus (P), sulfur (S) and a halogen element (D) and comprises a compound with an argyrodite-based crystal structure, wherein at least a part of the crystal structure is doped with indium (In) and tin (Sn), and ion conductivity at 30°C is at least 3.21 mS / cm.

Description

Solid electrolyte and all-solid-state battery containing the same

[0001] The present invention relates to a solid electrolyte and an all-solid-state battery including the same.

[0002]

[0003] Research on the safety issues and energy density of high-capacity batteries is attracting attention, and all-solid-state batteries are gaining attention as next-generation batteries.

[0004] The above all-solid-state battery is a battery that ensures battery safety because it replaces the liquid electrolyte that causes explosion with a solid electrolyte, does not use a flammable solvent in the battery, and thus does not cause any ignition or explosion due to a reaction such as the decomposition reaction of a conventional electrolyte.

[0005] Additionally, since lithium metal or a lithium alloy can be used as the negative electrode material, the energy density for the mass and volume of the battery can be improved.

[0006] Inorganic solid electrolytes are generally used as solid electrolytes for the above-mentioned all-solid-state batteries, and various studies are being conducted on sulfide-based solid electrolytes having a composition such as Li6PS5Cl having an argyrodite crystal structure among the above-mentioned all-solid-state batteries.

[0007] However, the above sulfide-based solid electrolyte has a problem in that, when configured into a cell, it exhibits inferior cell characteristics due to low lithium ion conductivity compared to liquid electrolytes used in conventional commercial lithium ion batteries.

[0008]

[0009] Accordingly, one object of the present invention is to provide a sulfide-based solid electrolyte having excellent ionic conductivity and an all-solid-state battery including the same.

[0010]

[0011] One embodiment of the present invention provides a sulfide-based solid electrolyte comprising a compound containing lithium (Li), phosphorus (P), sulfur (S), and a halogen element (D), having an argyrodite-based crystal structure, wherein at least a portion of the crystal structure is doped with indium (In) and tin (Sn), and having an ionic conductivity of 3.21 mS / cm or more at 30°C.

[0012] The compound may have a molar ratio of indium (In) to the compound of 0.013 to 0.055.

[0013] The above compound may have a molar ratio of indium (In) to phosphorus (P) ([In] / [P]) of 0.014 to 0.065.

[0014] The above compound may have a molar ratio of tin (Sn) to the compound of 0.035 to 0.45.

[0015] The above compound may have a molar ratio of tin (Sn) to phosphorus (P) ([Sn] / [P]) of 0.03 to 0.85.

[0016] The above compound may have a molar ratio of lithium (Li) to the compound of 3 to 5.7.

[0017] The above compound may have a molar ratio of sulfur (S) to the compound of 2.7 to 4.75.

[0018] The above compound may have a molar ratio of phosphorus (P) to the compound of 0.55 to 0.945.

[0019] The above compound may have a molar ratio of halogen element (D) to the compound of 1.15 to 2.4.

[0020] The above compound may have a molar ratio of halogen element (D) to phosphorus (P) ([D] / [P]) of 1.2 to 4.5.

[0021] The above compound can be represented by the following chemical formula 1.

[0022] [Chemical Formula 1]

[0023] Li 6(1-x-y) Inx Sn y P (1-x-y) S 5(1-x-y) D 1(1-x-y)+3x+4y

[0024] In the above chemical formula 1, 0.013≤x≤0.055, 0.035≤y≤0.45, and D is a halogen element such as F, Cl, Br, I, or a combination thereof.

[0025] In the above chemical formula 1, 0.02≤x≤0.035 may be satisfied.

[0026] In the above chemical formula 1, 0.08≤y≤0.17 may be satisfied.

[0027] The above compound can exhibit a peak in the range of 30.2˚≤2θ≤30.3˚ when analyzing an X-ray diffraction (XRD) pattern.

[0028]

[0029] Another embodiment of the present invention provides an all-solid-state battery comprising a positive electrode layer; a negative electrode layer, and a solid electrolyte layer positioned between the positive electrode layer and the negative electrode layer, wherein at least one of the positive electrode layer, the negative electrode layer, and the solid electrolyte layer comprises the solid electrolyte described above.

[0030]

[0031] A sulfide-based solid electrolyte according to one embodiment of the present invention can have improved ionic conductivity by including a compound in which at least a portion of the argyrodite-based crystal structure is doped with indium (In) and tin (Sn).

[0032]

[0033] Figure 1 is a graph showing the results of X-ray diffraction pattern analysis of solid electrolytes manufactured according to Example 1 and Comparative Example 1.

[0034]

[0035] The terms first, second, and third, etc., are used to describe, but are not limited to, various parts, components, regions, layers, and / or sections. These terms are used only to distinguish one part, component, region, layer, or section from another part, component, region, layer, or section. Accordingly, a first part, component, region, layer, or section described below may be referred to as a second part, component, region, layer, or section without departing from the scope of the present invention.

[0036] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the present invention. As used herein, the singular forms "singular" and "comprising" include plural forms as well, unless the context clearly dictates otherwise. The word "comprising" as used herein specifies a particular feature, region, integer, step, operation, element, and / or component, but does not exclude the presence or addition of other features, regions, integers, steps, operations, elements, and / or components.

[0037] When a part is referred to as being "on" or "over" another part, it can be directly on or over the other part, or there may be other parts intervening. Conversely, when a part is referred to as being "directly on" another part, there are no other parts intervening.

[0038] Although not defined otherwise, all terms, including technical and scientific terms, used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present invention pertains. Terms defined in commonly used dictionaries are further interpreted to have meanings consistent with the relevant technical literature and the present disclosure, and are not to be construed as ideal or overly formal unless otherwise defined.

[0039] Also, unless otherwise stated, % means weight%, and 1 ppm is 0.0001 weight%.

[0040] In this specification, the term "combination(s) thereof" described in the expression in the Makushi format means one or more mixtures or combinations selected from the group consisting of the components described in the expression in the Makushi format, and means including any one or more selected from the group consisting of said components.

[0041] Hereinafter, embodiments of the present invention will be described in detail so that those skilled in the art can easily implement them. However, the present invention may be implemented in various different forms and is not limited to the embodiments described herein.

[0042]

[0043] 1. Solid electrolyte

[0044] A sulfide-based solid electrolyte according to one embodiment of the present invention includes a compound containing lithium (Li), phosphorus (P), sulfur (S), and a halogen element (D), and having an argyrodite-based crystal structure.

[0045] At this time, in the sulfide-based solid electrolyte according to one embodiment of the present invention, at least a portion of the argyrodite-based crystal structure is doped with indium (In) and tin (Sn). Accordingly, a large number of vacancies due to lithium ion deficiency can be created, thereby forming a variety of lithium ion paths (channels), and thus the lithium ion conductivity of the solid electrolyte can be significantly improved.

[0046] Meanwhile, the sulfide-based solid electrolyte according to the present invention can be independently doped with indium (In) and tin (Sn). In other words, the doping amounts of indium and tin do not have a constant correlation with each other, but can be randomly adjusted as independent doping amounts. Accordingly, the aforementioned ionic conductivity enhancement effect of the solid electrolyte can be advantageously maximized.

[0047] At this time, the compound may have a molar ratio of indium (In) to the compound of 0.013 to 0.055, and more specifically, 0.02 to 0.035.

[0048] Alternatively, the compound may have a molar ratio of indium (In) to phosphorus (P) ([In] / [P]) of 0.014 to 0.065, more specifically 0.02 to 0.04.

[0049] If the indium content is too low, the indium doping amount may be too low, and the aforementioned effect of improving the ionic conductivity of the solid electrolyte may be minimal. If the indium content is too high, the argyrodite crystal structure may be significantly deformed due to excessive doping, making lithium ion movement difficult, and indium may not form the argyrodite crystal structure but exist as an impurity, which may actually reduce the ionic conductivity of the solid electrolyte. Therefore, when the indium content satisfies the above range, the effect of improving the ionic conductivity of the solid electrolyte can be preferably implemented.

[0050]

[0051] The above compound may have a molar ratio of tin (Sn) to the compound of 0.035 to 0.45, more specifically 0.08 to 0.17.

[0052] Alternatively, the compound may have a molar ratio of tin (Sn) to phosphorus (P) ([Sn] / [P]) of 0.03 to 0.85, more specifically 0.08 to 0.22.

[0053] If the tin content is too low, the tin doping amount may be too low, and the aforementioned effect of improving the ionic conductivity of the solid electrolyte may be minimal. If the tin content is too high, the argyrodite crystal structure may be significantly deformed due to excessive doping, making lithium ion movement difficult, and the tin may not form the argyrodite crystal structure but exist as an impurity, which may actually reduce the ionic conductivity of the solid electrolyte. Therefore, when the tin content satisfies the above range, the effect of improving the ionic conductivity of the solid electrolyte can be preferably implemented.

[0054]

[0055] The above compound may have a molar ratio of lithium (Li) to the compound of 3 to 5.7, more specifically 4.8 to 5.4.

[0056] Alternatively, the compound may have a molar ratio of lithium (Li) to phosphorus (P) ([Li] / [P]) of 5.5 to 6.5.

[0057] When the content of lithium in the compound according to the present invention satisfies the above range, the argyrodite crystal structure is fully maintained, so that the effect of improving the ion conductivity of the solid electrolyte can be more preferably implemented.

[0058]

[0059] The compound may have a molar ratio of sulfur (S) to the compound of 2.7 to 4.75, more specifically 4 to 4.5.

[0060] Alternatively, the compound may have a molar ratio of sulfur (S) to phosphorus (P) ([S] / [P]) of 4.5 to 5.5.

[0061] When the sulfur content in the compound according to the present invention satisfies the above range, the argyrodite crystal structure is fully maintained, so that the effect of improving the ion conductivity of the solid electrolyte can be more preferably implemented.

[0062]

[0063] The compound may have a molar ratio of phosphorus (P) to the compound of 0.55 to 0.945, more specifically 0.8 to 0.9.

[0064] When the content of phosphorus in the compound according to the present invention satisfies the above range, the argyrodite crystal structure is fully maintained, so that the effect of improving the ion conductivity of the solid electrolyte can be more preferably implemented.

[0065]

[0066] The compound may have a molar ratio of halogen element (D) to the compound of 1.15 to 2.4, more specifically 1.25 to 1.55.

[0067] Alternatively, the compound may have a molar ratio of halogen element (D) to phosphorus (P) ([D] / [P]) of 1.2 to 4.5, more specifically 1.35 to 1.95.

[0068] When the content of the halogen element in the compound according to the present invention satisfies the above range, the argyrodite crystal structure is fully maintained, so that the effect of improving the ion conductivity of the solid electrolyte can be more preferably implemented.

[0069]

[0070] The compound according to the present invention can be more specifically represented by the following chemical formula 1.

[0071] [Chemical Formula 1]

[0072] Li 6(1-x-y) In x Sn y P (1-x-y) S 5(1-x-y) D 1(1-x-y)+3x+4y

[0073] In the above chemical formula 1, 0.013≤x≤0.055, 0.035≤y≤0.45, and D is a halogen element such as F, Cl, Br, I, or a combination thereof.

[0074] In the above chemical formula 1, x represents the doping amount of indium, which is a doping element, expressed in moles. In this case, 0.013≤x≤0.055 may be satisfied, and more specifically, 0.02≤x≤0.035 may be satisfied.

[0075] If x is too small, the indium doping amount may be too small, so that the aforementioned effect of improving the ionic conductivity of the solid electrolyte may be minimal. If x is too large, the argyrodite crystal structure may be significantly deformed due to excessive doping, so that lithium ion movement may not be smooth, and tin may not form the argyrodite crystal structure but exist as an impurity phase, so that the ionic conductivity of the solid electrolyte may actually decrease. Therefore, when x satisfies the above range, the effect of improving the ionic conductivity of the solid electrolyte can be preferably implemented.

[0076] In the above chemical formula 1, y represents the doping amount of tin, which is a doping element, expressed in moles. In this case, 0.035≤y≤0.45 may be satisfied, and more specifically, 0.08≤y≤0.17 may be satisfied.

[0077] If y is too small, the tin doping amount may be too small, and the aforementioned effect of improving the ionic conductivity of the solid electrolyte may be minimal. If y is too large, the argyrodite crystal structure may be significantly deformed due to excessive doping, making lithium ion movement difficult, and tin may not form the argyrodite crystal structure but exist as an impurity phase, which may actually reduce the ionic conductivity of the solid electrolyte. Therefore, when y satisfies the above range, the effect of improving the ionic conductivity of the solid electrolyte can be preferably implemented.

[0078] In the above chemical formula 1, D represents a halogen element, and more specifically, may be F, Cl, Br, I, or a combination thereof.

[0079] However, from the viewpoint of structural stabilization of the solid electrolyte, ease of synthesis, and reduction of process cost, the halogen element (D) may be Cl.

[0080] In addition, from the viewpoint of more desirable implementation of ionic conductivity, the halogen element (D) may further include one or more elements selected from among Br and I in addition to Cl.

[0081] At this time, the molar ratio of one or more elements selected from Cl, Br, and I (Cl:Br and / or I) may be 3:7 to 7:3, and more specifically, may be 4:6 to 6:4. When the molar ratio of one or more elements selected from Cl, Br, and I (Cl:Br and / or I) satisfies the above range, ionic conductivity can be more preferably implemented.

[0082]

[0083] The above solid electrolyte may be in the form of particles or powder, and may be crystalline or amorphous.

[0084] In addition, the compound may exhibit a peak in the range of 30.2˚≤2θ≤30.3˚ when analyzing an X-ray diffraction (XRD) pattern. The peak in the above range indicates an argyrodite-based crystal phase, and by including the crystal phase, the ionic conductivity and battery electrochemical properties of the solid electrolyte may be preferably implemented.

[0085]

[0086] According to one embodiment of the present invention, a sulfide-based solid electrolyte is doped with indium and tin, and thus the ionic conductivity of the solid electrolyte is well implemented, so that the ionic conductivity at 30°C can be 3.21 mS / cm or more, and more specifically, 3.5 mS / cm, 4.0 mS / cm or 4.3 mS / cm or more.

[0087]

[0088] 2. Solid electrolyte manufacturing method

[0089] Another embodiment of the present invention provides a method for producing a sulfide-based solid electrolyte, comprising the steps of: forming a mixture by mixing a lithium raw material, a phosphorus raw material, a halogen element raw material, and a doping raw material; and heat-treating the mixture to form a compound having an argyrodite-based crystal structure, wherein the doping raw material includes an indium (In) compound and a tin (Sn) compound.

[0090] Hereinafter, a method for manufacturing a sulfide-based solid electrolyte according to another embodiment of the present invention will be described step by step.

[0091]

[0092] First, a mixture is formed by mixing lithium raw material, phosphorus raw material, halogen element raw material, and doping raw material.

[0093] At this time, the doping raw material includes an indium (In) compound and a tin (Sn) compound.

[0094] The above lithium raw material may be, for example, Li2S, Li2S2, or a combination thereof, but is not necessarily limited thereto.

[0095] The above raw material may be, for example, P2S5, P2O5 or a combination thereof, but is not necessarily limited thereto.

[0096] The above halogen element raw material may be, for example, LiF, LiCl, LiBr, LiI, or a combination thereof, but is not necessarily limited thereto. More specifically, the above halogen element raw material may be LiCl.

[0097] The above indium (In) compound may be more specifically InCl3. By using InCl3 as the indium compound, a composition rich in Cl content can be designed while doping In, so that the effect of improving the ion conductivity of the solid electrolyte can be more preferably implemented.

[0098] The above tin (Sn) compound may be more specifically SnCl4. By using SnCl4 as the tin compound, a composition rich in Cl content can be designed while doping Sn, so that the effect of improving the ion conductivity of the solid electrolyte can be more preferably implemented.

[0099] The input amounts of the lithium raw material, phosphorus raw material, halogen element raw material, and doping raw material can be stoichiometrically adjusted to suit the composition of the sulfide-based solid electrolyte compound according to the present invention.

[0100] The above mixing can be performed by mechanical mixing or chemical mixing.

[0101] The above mechanical mixing can be performed by, for example, a planetary mill, a paint shaker, a ball mill, a bead mill, a homogenizer, a hammer mill, a turbo mill, a disc mill, a planetary mill, a mechanofusion mill, etc.

[0102] The above chemical mixing can be performed, for example, by melt quenching.

[0103] The above mixing can be performed for 4 to 12 hours, specifically 6 to 10 hours, and more specifically 7 to 9 hours. If the mixing time is too short, the problem of insufficient mixing may occur. If the mixing time is too long, the mixing is completely completed within a certain amount of time, and even if further mixing is performed, the mixing state remains the same, which may cause problems in terms of process efficiency.

[0104] The above mixing can be performed at a rotation speed of 100 to 500 rpm, specifically 150 to 450 rpm, and more specifically 200 to 400 rpm. If the rotation speed is too slow, the balls may not be able to enter the inside of the powder particles, which may result in a problem of less overall mixing of the powder particles or less atomization of the powder particles due to low energy. On the other hand, if the rotation speed is too fast, the powder particles may be concentrated in one area, which may result in a problem of less even mixing.

[0105]

[0106] Next, optionally, after the step of forming the mixture, a step of compressing the mixture to form pellets may be further included.

[0107] At this time, the compression can be performed at a pressure of 100 to 500 Mpa, specifically 150 to 450 Mpa, more specifically 200 to 400 Mpa. If the pressure is too low, a problem may arise in that the interfacial resistance may increase due to insufficient bonding between the powder particles. On the other hand, if the pressure is too high, the bonding between the powder particles may already occur, and the bonding state may not change even if further pressure is applied, which may cause a problem in terms of process efficiency. Therefore, it is desirable in terms of productivity to form pellets at an appropriate pressure.

[0108]

[0109] Next, the mixture is heat-treated to form a sulfide-based solid electrolyte having an argyrodite-based crystal structure.

[0110] At this time, the heat treatment can be performed at a temperature of 400 to 700°C, and more specifically, can be performed at 500 to 600°C. If the heat treatment temperature is too low, the synthesis of a solid electrolyte having an argyrodite crystal structure may not occur sufficiently, or the solid electrolyte may be synthesized in an amorphous crystal structure, which may reduce the ionic conductivity of the solid electrolyte. If the heat treatment temperature is too high, the elements forming the solid electrolyte may vaporize, resulting in the loss of the solid electrolyte, or an impurity phase may be generated, which may reduce the ionic conductivity of the solid electrolyte.

[0111] In addition, the heat treatment may be performed for 2 to 8 hours, and more specifically, for 3 to 5 hours. If the heat treatment time is too short, the synthesis of the solid electrolyte having an argyrodite crystal structure may not occur sufficiently, or the solid electrolyte may be synthesized in an amorphous crystal structure, which may reduce the ionic conductivity of the solid electrolyte. If the heat treatment time is too long, the elements constituting the solid electrolyte may vaporize, resulting in the loss of the solid electrolyte, or an impurity phase may be generated, which may reduce the ionic conductivity of the solid electrolyte.

[0112] Additionally, the heat treatment may be performed in an inert gas atmosphere. Since the heat treatment is performed in an inert gas atmosphere, there may be an advantage in that contact with atmospheric moisture can be prevented. The inert gas atmosphere may be, for example, an Ar, N2, H2, or He atmosphere, and more specifically, an Ar atmosphere.

[0113]

[0114] 3. All-solid-state battery

[0115] Another embodiment of the present invention provides an all-solid-state battery comprising a positive electrode layer; a negative electrode layer, and a solid electrolyte layer positioned between the positive electrode layer and the negative electrode layer, wherein at least one of the positive electrode layer, the negative electrode layer, and the solid electrolyte layer comprises the above-described solid electrolyte.

[0116]

[0117] (bipolar layer)

[0118] More specifically, the above positive electrode layer may include a positive electrode current collector and a positive electrode active material layer disposed on the positive electrode current collector.

[0119] The above-described positive electrode active material layer may further include, for example, a positive electrode active material and optionally a solid electrolyte as needed. The solid electrolyte included in the positive electrode active material layer may be the same as or different from the solid electrolyte according to one embodiment of the present invention, and may be the same as or different from the solid electrolyte included in the solid electrolyte layer.

[0120] A cathode active material is a material that can reversibly absorb and desorb lithium ions. Examples of cathode active materials include, but are not limited to, lithium transition metal oxides such as lithium cobalt oxide (LCO), lithium nickel oxide, lithium nickel cobalt oxide, lithium nickel cobalt aluminum oxide (NCA), lithium nickel cobalt manganese oxide (NCM), lithium manganate, and lithium iron phosphate; nickel sulfide, copper sulfide, lithium sulfide, iron oxide, or vanadium oxide; and the like. Any material used as a cathode active material in the relevant technical field may be used. The cathode active materials may be singly or in a mixture of two or more.

[0121] The above lithium transition metal oxide is, for example, Li a A 1-b B b D2 (in the above formula, 0.90 ≤ a ≤ 1, and 0 ≤ b ≤ 0.5); Li a E 1-b B b O 2-c D c (In the above formula, 0.90 ≤ a ≤ 1, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05); LiE 2-bB b O 4-c D c (In the above formula, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05); Li a Ni 1-b-c Co b B c D α (In the above equation, 0.90 ≤ a ≤ 1, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, 0 < α ≤ 2); Li a Ni 1-b-c Co b B c O 2-α F α (In the above equation, 0.90 ≤ a ≤ 1, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, 0 < α < 2); Li a Ni 1-b-c Co b B c O 2-α F2 (in the above formula, 0.90 ≤ a ≤ 1, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, 0 < α < 2); Li a Ni 1-b-c Mn b B c D α (In the above equation, 0.90 ≤ a ≤ 1, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, 0 < α ≤ 2); Li a Ni 1-b-c Mn b B c O 2-α F α (In the above equation, 0.90 ≤ a ≤ 1, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, 0 < α < 2); Li a Ni 1-b-c Mn b B c O 2-α F2 (in the above formula, 0.90 ≤ a ≤ 1, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, 0 < α < 2); Li a Ni b E c G dO2 (in the above formula, 0.90 ≤ a ≤ 1, 0 ≤ b ≤ 0.9, 0 ≤ c ≤ 0.5, 0.001 ≤ d ≤ 0.1); Li a Ni b Co c Mn d GeO2 (in the above formula, 0.90 ≤ a ≤ 1, 0 ≤ b ≤ 0.9, 0 ≤ c ≤ 0.5, 0 ≤ d ≤ 0.5, 0.001 ≤ e ≤ 0.1); Li a NiG b O2 (in the above formula, 0.90 ≤ a ≤ 1, 0.001 ≤ b ≤ 0.1); Li a CoG b O2 (in the above formula, 0.90 ≤ a ≤ 1, 0.001 ≤ b ≤ 0.1); Li a MnG b O2 (in the above formula, 0.90 ≤ a ≤ 1, 0.001 ≤ b ≤ 0.1); Li a Mn2G b O4 (wherein 0.90 ≤ a ≤ 1, 0.001 ≤ b ≤ 0.1); QO2; QS2; LiQS2; V2O5; LiV2O5; LiIO2; LiNiVO4; Li (3-f) J2(PO4)3(0 ≤ f ≤ 2); Li (3-f)Fe2(PO4)3(0 ≤ f ≤ 2); A compound represented by any one of the chemical formulas of LiFePO4. In this compound, A is Ni, Co, Mn, or a combination thereof; B is Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, a rare earth element, or a combination thereof; D is O, F, S, P, or a combination thereof; E is Co, Mn, or a combination thereof; F is F, S, P, or a combination thereof; G is Al, Cr, Mn, Fe, Mg, La, Ce, Sr, V, or a combination thereof; Q is Ti, Mo, Mn, or a combination thereof; I is Cr, V, Fe, Sc, Y, or a combination thereof; J is V, Cr, Mn, Co, Ni, Cu, or a combination thereof. It is also possible to use a compound having a coating layer added to the surface of this compound, and it is also possible to use a mixture of the above-mentioned compound and the compound having a coating layer added. The coating layer added to the surface of these compounds includes a coating element compound of, for example, an oxide, a hydroxide, an oxyhydroxide of the coating element, an oxycarbonate of the coating element, or a hydroxycarbonate of the coating element of the coating element. The compound forming the coating layer is amorphous or crystalline. The coating elements included in the coating layer are Mg, Al, Co, K, Na, Ca, Si, Ti, V, Sn, Ge, Ga, B, As, Zr, or a mixture thereof. The method for forming the coating layer is selected within a range that does not adversely affect the physical properties of the positive electrode active material. The coating method includes, for example, spray coating and dipping. Since the specific coating method is well understood by those working in the relevant field, a detailed description thereof will be omitted.

[0122] The positive electrode active material layer may include, for example, a binder. The binder may include, but is not limited to, styrene butadiene rubber (SBR), polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, and the like, and any binder used in the art may be used.

[0123] The positive electrode active material layer may include, for example, a conductive material. The conductive material may include, but is not limited to, graphite, carbon black, acetylene black, Ketjen black, carbon fiber, metal powder, etc., and any conductive material used in the relevant technical field may be used.

[0124] The positive electrode active material layer may further include, for example, additives such as fillers, coating agents, dispersants, and ion conductive aids in addition to the above-described positive electrode active material, solid electrolyte, binder, and conductive agent.

[0125] As fillers, coating agents, dispersants, ion conductive aids, etc. that the positive electrode active material layer may include, known materials generally used in electrodes of all-solid-state secondary batteries can be used.

[0126] The positive electrode collector may be, for example, a plate or foil made of indium (In), copper (Cu), magnesium (Mg), stainless steel, titanium (Ti), iron (Fe), cobalt (Co), nickel (Ni), zinc (Zn), aluminum (Al), germanium (Ge), lithium (Li), or an alloy thereof. The thickness of the positive electrode collector may be, for example, 1 um to 100 um, 1 um to 50 um, 5 um to 25 um, or 10 um to 20 um.

[0127]

[0128] (cathode layer)

[0129] The above negative electrode layer may more specifically include a negative electrode current collector and a negative electrode active material layer disposed on the negative electrode current collector.

[0130] The above negative electrode active material layer may include, for example, a negative electrode active material and a binder, and may optionally further include a solid electrolyte as needed.

[0131] The above negative electrode active material may include, for example, a carbon-based negative electrode active material, a metal / metalloid negative electrode active material, or a combination thereof.

[0132] The above carbon-based negative electrode active material may be amorphous carbon, crystalline carbon, or a mixture or composite thereof. The amorphous carbon may be, for example, carbon black (CB), acetylene black (AB), furnace black (FB), ketjen black (KB), graphene, etc., but is not necessarily limited thereto, and any material classified as amorphous carbon in the relevant technical field may be used. Amorphous carbon is carbon that has no crystallinity or very low crystallinity, and is distinguished from crystalline carbon or graphitic carbon. The crystalline carbon may be, for example, natural graphite, artificial graphite, or a combination thereof.

[0133] The metal / metalloid negative electrode active material includes at least one selected from the group consisting of lithium (Li), gold (Au), platinum (Pt), palladium (Pd), silicon (Si), silver (Ag), aluminum (Al), bismuth (Bi), tin (Sn), and zinc (Zn), but is not necessarily limited thereto, and any metal negative electrode active material or metalloid negative electrode active material that forms an alloy or compound with lithium in the relevant technical field may be used.

[0134] The binder included in the negative electrode active material layer may be, for example, styrene-butadiene rubber (SBR), polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, vinylidene fluoride / hexafluoropropylene copolymer, polyacrylonitrile, polymethyl methacrylate, etc., but is not necessarily limited thereto, and any binder used in the relevant technical field may be used. The binder may be composed of a single binder or a plurality of different binders.

[0135] By including a binder in the negative electrode active material layer, the negative electrode active material layer is stabilized on the negative electrode current collector. Furthermore, cracking of the negative electrode active material layer is suppressed despite changes in volume and / or relative position of the negative electrode active material layer during the charge / discharge process.

[0136] The negative active material layer may further include additives used in conventional all-solid-state batteries, such as fillers, coating agents, dispersants, and ion conductive aids.

[0137] The all-solid-state battery may further include a second negative electrode active material layer disposed between the negative electrode current collector and the negative electrode active material layer during charging. The second negative electrode active material layer may be deposited between the negative electrode current collector and the negative electrode current collector during the charging process, or may be further disposed on the negative electrode active material layer during electrode assembly. The second negative electrode active material layer may be a metal layer containing lithium or a lithium alloy. The lithium alloy includes, but is not limited to, a Li-Al alloy, a Li-Sn alloy, a Li-In alloy, a Li-Ag alloy, a Li-Au alloy, a Li-Zn alloy, a Li-Ge alloy, a Li-Si alloy, and the like, and any lithium alloy used in the art may be used. The second negative electrode active material layer may be made of one of these alloys and / or lithium, or may be made of multiple types of alloys and / or lithium.

[0138] The negative electrode current collector may be composed of, for example, a material that does not react with lithium, i.e., does not form an alloy or compound. The negative electrode current collector may include, but is not limited to, copper (Cu), stainless steel, titanium (Ti), iron (Fe), cobalt (Co), and nickel (Ni), and any material that is used as an electrode current collector in the art may be used. The negative electrode current collector may be composed of one of the above-described metals, or may be composed of an alloy or a coating material of two or more metals. The negative electrode current collector may be, for example, in the form of a plate or foil.

[0139] When the negative electrode active material layer includes a solid electrolyte, the solid electrolyte included in the negative electrode active material layer may be the same as or different from the solid electrolyte according to one embodiment of the present invention, and may be the same as or different from the solid electrolyte included in the solid electrolyte layer.

[0140]

[0141] (solid electrolyte layer)

[0142] The above solid electrolyte layer can be manufactured by mixing and drying the above-described solid electrolyte and binder, or by rolling the above-described solid electrolyte powder into a certain shape under a pressure of 1 ton to 10 tons.

[0143] At this time, the solid electrolyte may be in the form of a powder or a molded product. The solid electrolyte in the form of a molded product may be in the form of, for example, pellets, sheets, thin films, etc., but is not necessarily limited to these and may have various forms depending on the intended use.

[0144] The above solid electrolyte layer may further include a solid electrolyte such as a conventional sulfide-based solid electrolyte and / or an oxide-based solid electrolyte in addition to the above-described solid electrolyte, if necessary.

[0145] The above binder may be, for example, styrene butadiene rubber (SBR), polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polyvinyl alcohol, etc., but is not limited thereto, and any binder used in the relevant technical field may be used. The binder of the solid electrolyte layer may be the same as or different from the binders of the positive and negative electrode layers.

[0146]

[0147] Hereinafter, embodiments of the present invention will be described in more detail through examples. However, the following examples are merely preferred embodiments of the present invention, and the present invention is not limited to the following examples.

[0148]

[0149] Example 1: Li 5.58 In 0.02 Sn 0.05 P 0.93 S 4.65 Cl 1.19 Solid electrolyte manufacturing

[0150] The final product is Li 6(1-x-y) In x Sn y P (1-x-y) S 5(1-x-y) In the Cl1(1-xy)+3x+4y solid electrolyte, the reactants Li2S, P2S5, LiCl, InCl3, and SnCl4 were quantitatively measured so that x=0.02 and y=0.05, and the mixture was formed by mixing at 300 rpm for about 8 hours using a planetary mill.

[0151] Next, a pressure of 300 MPa was applied to the mixture to form pellets.

[0152] Next, the pellets were heat-treated at 550°C for about 4 hours in an argon (Ar) atmosphere to obtain Li 5.58 Al 0.02 Sn0.05 P 0.93 S 4.65 Cl 1.19 A solid electrolyte was prepared.

[0153]

[0154] Example 2: Li 5.28 In 0.02 Sn 0.1 P 0.88 S 4.4 Cl 1.34 Solid electrolyte manufacturing

[0155] The final product is Li 6(1-x-y) In x Sn y P (1-x-y) S 5(1-x-y) A solid electrolyte was manufactured in the same manner as in Example 1, except that the reactants Li2S, P2S5, LiCl, InCl3, and SnCl4 were quantified so that x=0.02 and y=0.1 in the Cl1(1-xy)+3x+4y solid electrolyte.

[0156]

[0157] Example 3: Li 4.98 In 0.02 Sn 0.15 P 0.83 S 4.15 Cl 1.49 Solid electrolyte manufacturing

[0158] The final product is Li 6(1-x-y) In x Sn y P (1-x-y) S 5(1-x-y) A solid electrolyte was manufactured in the same manner as in Example 1, except that the reactants Li2S, P2S5, LiCl, InCl3, and SnCl4 were quantified so that x=0.02 and y=0.15 in the Cl1(1-xy)+3x+4y solid electrolyte.

[0159]

[0160] Example 4: Li 4.68 In 0.02 Sn 0.2 P 0.78 S 3.9 Cl 1.64 Solid electrolyte manufacturing

[0161] The final product is Li 6(1-x-y) In x Sn y P (1-x-y) S 5(1-x-y) A solid electrolyte was manufactured in the same manner as in Example 1, except that the reactants Li2S, P2S5, LiCl, InCl3, and SnCl4 were quantified so that x=0.02 and y=0.2 in the Cl1(1-xy)+3x+4y solid electrolyte.

[0162]

[0163] Example 5: Li 4.08 In 0.02 Sn 0.3 P 0.68 S 3.4 Cl 1.94 Solid electrolyte manufacturing

[0164] The final product is Li 6(1-x-y) In x Sn y P (1-x-y) S 5(1-x-y) A solid electrolyte was manufactured in the same manner as in Example 1, except that the reactants Li2S, P2S5, LiCl, InCl3, and SnCl4 were quantified so that x=0.02 and y=0.3 in the Cl1(1-xy)+3x+4y solid electrolyte.

[0165]

[0166] Example 6: Li 3.48 In 0.02 Sn 0.4 P 0.58 S 2.9 Cl 2.24 Solid electrolyte manufacturing

[0167] The final product is Li 6(1-x-y) In x Sn y P (1-x-y) S 5(1-x-y)A solid electrolyte was manufactured in the same manner as in Example 1, except that the reactants Li2S, P2S5, LiCl, InCl3, and SnCl4 were quantified so that x=0.02 and y=0.4 in the Cl1(1-xy)+3x+4y solid electrolyte.

[0168]

[0169] Example 7: Li 5.31 In 0.015 Sn 0.1 P 0.885 S 4.425 Cl 1.33 Solid electrolyte manufacturing

[0170] The final product is Li 6(1-x-y) In x Sn y P (1-x-y) S 5(1-x-y) A solid electrolyte was manufactured in the same manner as in Example 1, except that the reactants Li2S, P2S5, LiCl, InCl3, and SnCl4 were quantified so that x=0.015 and y=0.1 in the Cl1(1-xy)+3x+4y solid electrolyte.

[0171]

[0172] Example 8: Li 5.25 In 0.025 Sn 0.1 P 0.875 S 4.375 Cl 1.35 Solid electrolyte manufacturing

[0173] The final product is Li 6(1-x-y) In x Sn y P (1-x-y) S 5(1-x-y) A solid electrolyte was manufactured in the same manner as in Example 1, except that the reactants Li2S, P2S5, LiCl, InCl3, and SnCl4 were quantified so that x=0.025 and y=0.1 in the Cl1(1-xy)+3x+4y solid electrolyte.

[0174]

[0175] Example 9: Li 5.22 In 0.03 Sn0.1 P 0.87 S 4.35 Cl 1.36 Solid electrolyte manufacturing

[0176] The final product is Li 6(1-x-y) In x Sn y P (1-x-y) S 5(1-x-y) A solid electrolyte was manufactured in the same manner as in Example 1, except that the reactants Li2S, P2S5, LiCl, InCl3, and SnCl4 were quantified so that x=0.03 and y=0.1 in the Cl1(1-xy)+3x+4y solid electrolyte.

[0177]

[0178] Example 10: Li 5.16 In 0.04 Sn 0.1 P 0.86 S 4.3 Cl 1.38 Solid electrolyte manufacturing

[0179] The final product is Li 6(1-x-y) In x Sn y P (1-x-y) S 5(1-x-y) A solid electrolyte was manufactured in the same manner as in Example 1, except that the reactants Li2S, P2S5, LiCl, InCl3, and SnCl4 were quantified so that x=0.04 and y=0.1 in the Cl1(1-xy)+3x+4y solid electrolyte.

[0180]

[0181] Example 11: Li 5.1 In 0.05 Sn 0.1 P 0.85 S 4.25 Cl 1.4 Solid electrolyte manufacturing

[0182] The final product is Li 6(1-x-y) In x Sn y P (1-x-y) S 5(1-x-y)A solid electrolyte was manufactured in the same manner as in Example 1, except that the reactants Li2S, P2S5, LiCl, InCl3, and SnCl4 were quantified so that x=0.05 and y=0.1 in the Cl1(1-xy)+3x+4y solid electrolyte.

[0183]

[0184] Comparative Example 1: Preparation of Li6PS5Cl solid electrolyte

[0185] The reactants Li2S, P2S5, and LiCl were mixed using a planetary mill at 300 rpm for about 8 hours to form a mixture.

[0186] Next, a pressure of 300 MPa was applied to the mixture to form pellets.

[0187] Next, the pellets were heat-treated at 550°C in an argon (Ar) atmosphere to prepare a Li6PS5Cl solid electrolyte.

[0188]

[0189] Comparative Example 2: Li 5.58 In 0.02 P 0.98 S 4.9 Cl 1.04 Solid electrolyte manufacturing

[0190] The final product is Li 6(1-x-y) In x Sn y P (1-x-y) S 5(1-x-y) A solid electrolyte was manufactured in the same manner as in Example 1, except that the reactants Li2S, P2S5, LiCl, and InCl3 were quantified so that x=0.02 and y=0 in the Cl1(1-xy)+3x+4y solid electrolyte.

[0191]

[0192] Comparative Example 3: Li 5.4 Sn 0.1 P 0.9 S 4.5 Cl 1.3 Solid electrolyte manufacturing

[0193] The final product is Li 6(1-x-y) In x Sn y P (1-x-y) S 5(1-x-y) A solid electrolyte was manufactured in the same manner as in Example 1, except that the reactants Li2S, P2S5, LiCl, and SnCl4 were quantified so that x=0, y=0.1 in the Cl1(1-xy)+3x+4y solid electrolyte.

[0194]

[0195] Comparative Example 4: Li 5.76 In 0.02 Sn 0.02 P 0.96 S 4.8 Cl 1.1 Solid electrolyte manufacturing

[0196] The final product is Li 6(1-x-y) In x Sn y P (1-x-y) S 5(1-x-y) A solid electrolyte was manufactured in the same manner as in Example 1, except that the reactants Li2S, P2S5, LiCl, InCl3, and SnCl4 were quantified so that x=0.02 and y=0.02 in the Cl1(1-xy)+3x+4y solid electrolyte.

[0197]

[0198] Comparative Example 5: Li 2.88 In 0.02 Sn 0.5 P 0.48 S 2.4 Cl 2.54 Solid electrolyte manufacturing

[0199] The final product is Li 6(1-x-y) In x Sn y P (1-x-y) S 5(1-x-y) A solid electrolyte was manufactured in the same manner as in Example 1, except that the reactants Li2S, P2S5, LiCl, InCl3, and SnCl4 were quantified so that x=0.02 and y=0.5 in the Cl1(1-xy)+3x+4y solid electrolyte.

[0200]

[0201] Comparative Example 6: Li 5.37 In 0.005 Sn 0.1 P 0.895 S 4.475 Cl 1.31 Solid electrolyte manufacturing

[0202] The final product is Li 6(1-x-y) In x Sn y P (1-x-y) S 5(1-x-y) A solid electrolyte was manufactured in the same manner as in Example 1, except that the reactants Li2S, P2S5, LiCl, InCl3, and SnCl4 were quantified so that x=0.005 and y=0.1 in the Cl1(1-xy)+3x+4y solid electrolyte.

[0203]

[0204] Comparative Example 7: Li 5.34 In 0.01 Sn 0.1 P 0.89 S 4.45 Cl 1.32 Solid electrolyte manufacturing

[0205] The final product is Li 6(1-x-y) In x Sn y P (1-x-y) S 5(1-x-y) A solid electrolyte was manufactured in the same manner as in Example 1, except that the reactants Li2S, P2S5, LiCl, InCl3, and SnCl4 were quantified so that x=0.01 and y=0.1 in the Cl1(1-xy)+3x+4y solid electrolyte.

[0206]

[0207] Comparative Example 8: Li 5.04 In 0.06 Sn 0.1 P 0.84 S 4.2 Cl 1.42 Solid electrolyte manufacturing

[0208] The final product is Li 6(1-x-y) In x Sn y P(1-x-y) S 5(1-x-y) A solid electrolyte was manufactured in the same manner as in Example 1, except that the reactants Li2S, P2S5, LiCl, InCl3, and SnCl4 were quantified so that x=0.06 and y=0.1 in the Cl1(1-xy)+3x+4y solid electrolyte.

[0209]

[0210] Tables 1 and 2 below are tables summarizing the experimental results according to Experimental Examples 2 and 3 described below for the solid electrolytes of Examples and Comparative Examples.

[0211] Composition [Li] / [P][In] / [P][Sn] / [P][S] / [P][Cl] / [P]Comparative Example 1Li6PS5Cl60.0000.0005.0001.000Comparative Example 2Li 5.58 In 0.02 P 0.98 S 4.9 Cl 1.04 60.0200.0005.0001.061Comparative Example 3Li 5.4 Sn 0.1 P 0.9 S 4.5 Cl 1.3 60.0000.1115.0001.444 Comparative Example 4Li 5.76 In 0.02 Sn 0.02 P 0.96 S 4.8 Cl 1.1 60.0210.0215.0001.146 Example 1Li 5.58 In 0.02 Sn 0.05 P 0.93 S 4.65 Cl 1.19 60.0220.0545.0001.280 Example 2Li 5.28 In 0.02 Sn 0.1 P 0.88 S 4.4 Cl 1.34 60.0230.1145.0001.523 Example 3Li 4.98 In 0.02 Sn 0.15 P 0.83 S 4.15 Cl1.49 60.0240.1815.0001.795 Example 4Li 4.68 In 0.02 Sn 0.2 P 0.78 S 3.9 Cl 1.64 60.0260.2565.0002.103 Example 5Li 4.08 In 0.02 Sn 0.3 P 0.68 S 3.4 Cl 1.94 60.0290.4415.0002.853 Example 6Li 3.48 In 0.02 Sn 0.4 P 0.58 S 2.9 Cl 2.24 60.0340.6905.0003.862 Comparative Example 5Li 2.88 In 0.02 Sn 0.5 P 0.48 S 2.4 Cl 2.54 60.0421.0425.0005.292 Comparative Example 6Li 5.37 In 0.005 Sn 0.1 P 0.895 S 4.475 Cl 1.31 60.0060.1125.0001.464 Comparative Example 7Li 5.34 In 0.01 Sn 0.1 P 0.89 S 4.45 Cl 1.32 60.0110.1125.0001.483 Example 7Li 5.31 In 0.015 Sn 0.1 P 0.885 S 4.425 Cl 1.33 60.0170.1135.0001.503 Example 8Li 5.25 In 0.025 Sn 0.1 P 0.875 S 4.375 Cl 1.35 60.0290.1145.0001.543 Example 9Li 5.22 In 0.03 Sn 0.1 P0.87 S 4.35 Cl 1.36 60.0340.1155.0001.563 Example 10Li 5.16 In 0.04 Sn 0.1 P 0.86 S 4.3 Cl 1.38 60.0470.1165.0001.605 Example 11Li 5.1 In 0.05 Sn 0.1 P 0.85 S 4.25 Cl 1.4 60.0590.1185.0001.647 Comparative Example 8Li 5.04 In 0.06 Sn 0.1 P 0.84 S 4.2 Cl 1.42 60.0710.1195.0001.690

[0212] Composition xy Ionic conductivity [mS / cm] Comparative example 1Li6PS5Cl003.2 Comparative example 2Li 5.58 In 0.02 P 0.98 S 4.9 Cl 1.04 0.0201.81Comparative example 3Li 5.4 Sn 0.1 P 0.9 S 4.5 Cl 1.3 00.11.61 Comparative Example 4Li 5.76 In 0.02 Sn 0.02 P 0.96 S 4.8 Cl 1.1 0.020.022.31Example 1Li 5.58 In 0.02 Sn 0.05 P 0.93 S 4.65 Cl 1.19 0.053.48 Example 2Li 5.28 In 0.02 Sn 0.1 P 0.88 S 4.4 Cl 1.34 0.14.46 Example 3Li 4.98 In 0.02 Sn 0.15 P0.83 S 4.15 Cl 1.49 0.154.37 Example 4Li 4.68 In 0.02 Sn 0.2 P 0.78 S 3.9 Cl 1.64 0.23.86 Example 5Li 4.08 In 0.02 Sn 0.3 P 0.68 S 3.4 Cl 1.94 0.33.53 Example 6Li 3.48 In 0.02 Sn 0.4 P 0.58 S 2.9 Cl 2.24 0.43.47 Comparative Example 5Li 2.88 In 0.02 Sn 0.5 P 0.48 S 2.4 Cl 2.54 0.53.13 Comparative example 6Li 5.37 In 0.005 Sn 0.1 P 0.895 S 4.475 Cl 1.31 0.0050.12.23Comparative example 7Li 5.34 In 0.01 Sn 0.1 P 0.89 S 4.45 Cl 1.32 0.012.25 Example 7Li 5.31 In 0.015 Sn 0.1 P 0.885 S 4.425 Cl 1.33 0.0153.75 Example 8Li 5.25 In 0.025 Sn 0.1 P 0.875 S 4.375 Cl 1.35 0.0254.54 Example 9Li 5.22 In 0.03 Sn 0.1 P 0.87 S 4.35 Cl 1.36 0.034.39 Example 10Li 5.16 In 0.04 Sn0.1 P 0.86 S 4.3 Cl 1.38 0.043.64Example 11Li 5.1 In 0.05 Sn 0.1 P 0.85 S 4.25 Cl 1.4 0.053.23Comparative example 8Li 5.04 In 0.06 Sn 0.1 P 0.84 S 4.2 Cl 1.42 0.063.12

[0213]

[0214] Experimental Example 1: XRD Diffraction Analysis Experiment

[0215] An XRD (X-ray diffraction) diffraction analysis experiment was conducted on the solid electrolyte manufactured according to Example 1 and Comparative Example 1, and the results are shown in Fig. 1.

[0216] Referring to Fig. 1, the solid electrolytes manufactured according to Example 1 and Comparative Example 1 exhibited peaks in the range of 30.2˚≤2θ≤30.3˚ when analyzed by X-ray diffraction (XRD) patterns. Through this, it was confirmed that the solid electrolytes of the Examples and Comparative Examples had an argyrodite crystal structure.

[0217]

[0218] Experimental Example 2: Analysis of Solid Electrolyte Composition and Evaluation of Ionic Conductivity

[0219] (1) Composition analysis

[0220] The composition of the solid electrolyte was measured using an Inductively Coupled Plasma Emission Spectrometry (ICP) device. More specifically, all synthesized solid electrolyte samples were dissolved in HNO3 solvent, diluted with DI water, and the element contents were measured using an ICP device.

[0221] (2) Ionic conductivity evaluation (30℃, 0.1C)

[0222] We conducted experiments to evaluate the ionic conductivity of solid electrolytes using a pressure powder cell. Specifically, the synthesized solid electrolyte was pulverized and then manufactured into pellets under a pressure of 300 MPa. The cell was then fabricated using SUS as the working electrode at a pressure of 70 MPa. Impedance was then measured at 30°C and a voltage of 10 mV was applied.

[0223]

[0224] Referring to Tables 1 and 2, it was confirmed that the solid electrolytes of Examples 1 to 11, in which both indium and tin were doped and the doping amounts of phosphorus and tin or the ranges of x and y were appropriately adjusted to the ranges according to the present invention, had improved ionic conductivity compared to Comparative Example 1, which is a basic argyrodite crystal structure solid electrolyte.

[0225] On the other hand, it was confirmed that the solid electrolytes of Comparative Example 2, which was doped only with indium, and Comparative Example 3, which was doped only with tin, had lower ionic conductivity than Comparative Example 1, which was a basic argyrodite crystal structure solid electrolyte.

[0226] In addition, in Comparative Examples 4, 5, 6, 7, and 8, in which both indium and tin were doped but the doping amounts of indium and tin or the ranges of x and y were not properly controlled, it was confirmed that the ionic conductivity was lower than that of Comparative Example 1, which is a basic argyrodite crystal structure solid electrolyte.

[0227] Comparing the examples in more detail, it was confirmed that when the doping amount of indium and tin or the ranges of x and y were more appropriately controlled, the ionic conductivity was greatly improved to a level of 4.0 mS / cm or more.

[0228]

[0229] Although the preferred embodiments of the present invention have been described above, the present invention is not limited thereto, and various modifications can be made within the scope of the patent claims, the detailed description of the invention, and the attached drawings, and it is obvious that this also falls within the scope of the present invention.

[0230] Accordingly, the actual scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A compound containing lithium (Li), phosphorus (P), sulfur (S) and a halogen element (D) and having an argyrodite crystal structure, At least a portion of the above crystal structure is doped with indium (In) and tin (Sn), A sulfide-based solid electrolyte having an ionic conductivity of 3.21 mS / cm or more at 30°C.

2. In paragraph 1, The above compound is a sulfide-based solid electrolyte having a molar ratio of indium (In) to the compound of 0.013 to 0.

055.

3. In paragraph 1, The above compound is a sulfide-based solid electrolyte having a molar ratio of indium (In) to phosphorus (P) ([In] / [P]) of 0.014 to 0.

065.

4. In paragraph 1, The above compound is a sulfide-based solid electrolyte having a molar ratio of tin (Sn) to the compound of 0.035 to 0.

45.

5. In paragraph 1, The above compound is a sulfide-based solid electrolyte having a molar ratio of tin (Sn) to phosphorus (P) ([Sn] / [P]) of 0.03 to 0.

85.

6. In paragraph 1, The above compound is a sulfide-based solid electrolyte having a molar ratio of lithium (Li) to the compound of 3 to 5.

7.

7. In paragraph 1, The above compound is a sulfide-based solid electrolyte having a molar ratio of sulfur (S) to the compound of 2.7 to 4.

75.

8. In paragraph 1, The above compound is a sulfide-based solid electrolyte having a molar ratio of phosphorus (P) to the compound of 0.55 to 0.

945.

9. In paragraph 1, The above compound is a sulfide-based solid electrolyte having a molar ratio of halogen element (D) to the compound of 1.15 to 2.

4.

10. In paragraph 1, The above compound is a sulfide-based solid electrolyte having a molar ratio of halogen element (D) to phosphorus (P) ([D] / [P]) of 1.2 to 4.

5.

11. In paragraph 1, The above compound is a sulfide-based solid electrolyte represented by the following chemical formula 1: [Chemical Formula 1] Li 6(1-x-y) In x Sn y P (1-x-y) S 5(1-x-y) D 1(1-x-y)+3x+4y In the chemical formula 1 above, 0.013≤x≤0.055, 0.035≤y≤0.45, and D is a halogen element such as F, Cl, Br, I, or a combination thereof.

12. In paragraph 11, Sulfide-based solid electrolyte with 0.02≤x≤0.

035.

13. In paragraph 11, Sulfide-based solid electrolyte with 0.08≤y≤0.

17.

14. In paragraph 1, The above compound is a sulfide-based solid electrolyte that exhibits a peak in the range of 30.2˚≤2θ≤30.3˚ when analyzed by X-ray diffraction (XRD) pattern.

15. Including a positive electrode layer; a negative electrode layer and a solid electrolyte layer positioned between the positive electrode layer and the negative electrode layer, An all-solid-state battery, wherein at least one of the positive electrode layer, the negative electrode layer, and the solid electrolyte layer comprises a solid electrolyte according to claim 1.

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