Solid electrolyte, method for manufacturing same, and all-solid-state battery including same

Abstract

The present invention relates to a sulfide-based solid electrolyte comprising lithium (Li), phosphorus (P), oxygen (O), sulfur (S), and two or more halogen elements, wherein the sulfide-based solid electrolyte has an argyrodite-based crystal structure, and a 31P-NMR spectrum of the sulfide-based solid electrolyte satisfies formula 1: [Formula 1] C / A≥3.5 In formula 1, A is the area of a peak appearing at 85 to 87 ppm, and C is the area of a peak appearing at 82 to 83 ppm.

Description

Solid electrolyte, method for manufacturing the same, and all-solid-state battery including the same

[0001] The present invention relates to a solid electrolyte, a method for manufacturing the same, and an all-solid-state battery comprising the same.

[0002] This application claims priority to Korean Patent Application No. 10-2024-0191966, filed on December 19, 2024, the entire contents of which are incorporated herein by reference.

[0003] With the recent increase in demand for electric vehicles, the demand for high-energy, high-output lithium-ion batteries is also rising. Lithium-ion batteries have the advantage of higher energy density and greater capacity per unit area compared to nickel-manganese or nickel-cadmium batteries.

[0004] However, conventional lithium-ion batteries mainly used flammable organic liquid electrolytes as electrolytes, which caused safety issues such as overheating. Recently, all-solid-state batteries using non-flammable solid electrolytes have been gaining attention.

[0005] All-solid-state batteries are batteries that ensure safety by replacing the liquid electrolyte, which causes explosions, with a solid electrolyte and eliminating the use of flammable solvents within the battery, thereby preventing any ignition or explosion caused by the decomposition reaction of conventional electrolytes.

[0006] Inorganic solid electrolytes are generally used in all-solid-state batteries. Among solid electrolytes, sulfides are characterized by high ionic conductivity and relative flexibility, making it easy to form solid-solid interfaces. Additionally, they are stable with respect to active materials, leading to various ongoing studies on sulfide-based solid electrolytes.

[0007] However, sulfide-based solid electrolytes generate hydrogen sulfide (H2S) gas upon contact with humid air, which causes a degradation in conductivity and can lead to a problem of reduced performance in cell characteristics compared to lithium secondary batteries using liquid electrolytes.

[0008] Accordingly, there is a need to develop technology that can improve electrochemical characteristics without degrading the ionic conductivity of sulfide-based solid electrolytes or the cell performance of all-solid-state batteries.

[0009] One objective of the present invention is to provide a sulfide-based solid electrolyte that includes heterogeneous halogen elements and does not cause degradation of ionic conductivity.

[0010] Another objective of the present invention is to provide a method for manufacturing a sulfide-based solid electrolyte having the aforementioned advantages.

[0011] Another objective of the present invention is to provide an all-solid-state battery with improved electrochemical properties without degradation of cell performance by including a sulfide-based solid electrolyte having the aforementioned advantages.

[0012] A sulfide-based solid electrolyte according to one embodiment of the present invention is a sulfide-based solid electrolyte comprising lithium (Li), phosphorus (P), oxygen (O), sulfur (S), and two or more halogen elements, wherein the sulfide-based solid electrolyte has an azirodite crystal structure, and the sulfide-based solid electrolyte 31 The P-NMR spectrum satisfies Equation 1 below.

[0013] [Equation 1]

[0014] C / A≥3.5

[0015] In the above Equation 1, A represents the peak area appearing at 85 to 87 ppm, and C represents the peak area appearing at 82 to 83 ppm.

[0016] of the above sulfide-based solid electrolyte 31 The P-NMR spectrum may satisfy Equation 2 below.

[0017] [Equation 2]

[0018] 3.5≤C / A≤10

[0019] In the above Equation 2, A and C are as defined in the above Equation 1.

[0020] of the above sulfide-based solid electrolyte 31 The P-NMR spectrum may satisfy Equation 3 below.

[0021] [Equation 3]

[0022] 1.3≤C / B≤10

[0023] In the above Equation 3, B represents the area of ​​the peak appearing at 83 to 85 ppm, and C represents the area of ​​the peak appearing at 82 to 83 ppm.

[0024] The above halogen elements may include at least two of Cl, Br, I, and F.

[0025] The above sulfide-based solid electrolyte may have a molar ratio of lithium (Li) to phosphorus (P) ([Li] / [P]) of 5.60 to 6.07.

[0026] The above sulfide-based solid electrolyte may have a molar ratio of sulfur (S) to phosphorus (P) ([S] / [P]) of 4.60 to 5.07.

[0027] The above sulfide-based solid electrolyte may have a molar ratio of oxygen (O) to phosphorus (P) ([O] / [P]) of 0.12 to 1.69.

[0028] The above sulfide-based solid electrolyte may have a molar ratio ([D] / [P]) of two or more halogen elements (D) to phosphorus (P) of 1.0 to 1.4.

[0029] The above sulfide-based solid electrolyte can be represented by the following chemical formula 1.

[0030] [Chemical Formula 1]

[0031] Li(xy-x-5y+7)P (1-y) S (xy-x-5y+6) O 4y Cl(x-xy)(1-z)F z

[0032] In the above chemical formula 1, 1≤x≤2, 0.01≤y≤0.3, and 0.01≤z≤0.3.

[0033] A method for manufacturing a sulfide-based solid electrolyte according to another embodiment of the present invention comprises: a step of preparing two or more types of raw materials, such as a lithium compound, a phosphorus compound, and a halogen compound; a step of mixing a doping material with the raw materials to form a mixture; and a step of heat-treating the mixture to form a sulfide-based solid electrolyte having an azirodite-based crystal structure.

[0034] The above heat treatment temperature may be 300 to 490℃.

[0035] The above halogen compound may include at least two of LiCl, LiF, LiBr, and LiI.

[0036] The amount of LiCl added above may be 0.049 to 1.96 mol% based on the total moles of the mixture.

[0037] The amount of LiF added may be 0.01 to 0.3 mol% based on the total mixture.

[0038] A solid-state battery according to another embodiment of the present invention comprises a positive electrode layer; a negative electrode layer; and a solid electrolyte layer disposed between the positive electrode layer and the negative electrode layer, wherein one or more of the positive electrode layer, the negative electrode layer, and the solid electrolyte layer comprises the aforementioned sulfide-based solid electrolyte.

[0039] A sulfide-based solid electrolyte according to one embodiment of the present invention can suppress the deterioration of ion conductivity by including a different type of halogen element.

[0040] An all-solid-state battery according to another embodiment of the present invention can improve initial capacity and lifespan characteristics by including the aforementioned sulfide-based solid electrolyte.

[0041] FIG. 1 shows the nuclear magnetic resonance spectrum of phosphorus in a sulfide-based solid electrolyte according to one embodiment and a comparative example of the present invention ( 31 This is the P-NMR measurement result.

[0042] In this specification, terms such as first, second, and third are used to describe various parts, components, regions, layers, and / or sections, but are not limited thereto. These terms are used solely to distinguish one part, component, region, layer, or section from another part, component, region, layer, or section. Accordingly, the first part, component, region, layer, or section described below may be referred to as the second part, component, region, layer, or section without departing from the scope of the invention.

[0043] The technical terms used herein are for the reference of specific embodiments only and are not intended to limit the invention. The singular forms used herein include plural forms unless phrases clearly indicate otherwise. As used in the specification, the meaning of "comprising" specifies certain characteristics, areas, integers, steps, actions, elements, and / or components, and does not exclude the presence or addition of other characteristics, areas, integers, steps, actions, elements, and / or components.

[0044] When it is stated that one part is "on" or "on" another part, it may be directly on or on the other part, or another part may be involved in between. In contrast, when it is stated that one part is "directly on" another part, no other part is interposed in between.

[0045] Unless otherwise defined, all terms used herein, including technical and scientific terms, have the same meaning as generally understood by those skilled in the art to which this invention pertains. Terms defined in commonly used dictionaries are further interpreted to have meanings consistent with relevant technical literature and the present disclosure, and are not interpreted in an ideal or highly formal sense unless otherwise defined.

[0046] Also, unless otherwise specified, % means weight %, and 1 ppm is 0.0001 weight %.

[0047] In this specification, the term “combination(s) of these” described in the Markush-type expression means one or more mixtures or combinations selected from the group consisting of the components described in the Markush-type expression, and means including any one or more selected from the group consisting of said components.

[0048] Hereinafter, embodiments of the present invention are described in detail so that those skilled in the art can easily implement the invention. However, the present invention may be embodied in various different forms and is not limited to the embodiments described herein.

[0049] Sulfide-based solid electrolytes

[0050] A sulfide-based solid electrolyte according to one embodiment of the present invention is a sulfide-based solid electrolyte comprising lithium (Li), phosphorus (P), oxygen (O), sulfur (S), and two or more halogen elements, wherein the sulfide-based solid electrolyte has an azirodite crystal structure, and the sulfide-based solid electrolyte 31 The P-NMR spectrum satisfies Equation 1 below.

[0051] [Equation 1]

[0052] C / A≥3.5

[0053] In the above Equation 1, A represents the peak area appearing at 85 to 87 ppm, and C represents the peak area appearing at 82 to 83 ppm.

[0054] Specifically, the above sulfide-based solid electrolyte 31 The P-NMR spectrum can satisfy Equation 2 below.

[0055] [Equation 2]

[0056] 3.5≤C / A≤10

[0057] In Equation 2 above, A and C are as defined in Equation 1 above. If Equations 1 and 2 satisfy the above range, electrochemical characteristics can be improved without deterioration of the ionic conductivity and cell performance of the sulfide-based solid electrolyte. On the other hand, if C / A is too low, H2S gas is generated due to side reactions between the sulfide-based solid electrolyte and moisture, which may degrade the cell characteristics of the all-solid-state battery.

[0058] In one embodiment, the sulfide-based solid electrolyte 31 The P-NMR spectrum can satisfy Equation 3 below.

[0059] [Equation 3]

[0060] 1.3≤C / B≤10

[0061] In the above Equation 3, B represents the area of ​​the peak appearing at 83 to 85 ppm, and C represents the area of ​​the peak appearing at 82 to 83 ppm. If the above Equation 3 satisfies the above range, the moisture stability of the sulfide-based solid electrolyte can be improved. On the other hand, if C / B falls outside the above range, a problem may arise in which the electrochemical characteristics of the all-solid-state battery deteriorate. Specifically, A P1 may be a peak originating from an azirodite-based crystal phase, B may be a peak originating from an amorphous phase related to an azirodite-based crystal phase, and C may be a peak originating from a crystal phase other than an azirodite-based crystal phase.

[0062] In one embodiment, the halogen element may include at least two of Cl, Br, I, and F, but is not limited thereto, and any material capable of improving the moisture stability and ionic conductivity of the sulfide-based solid electrolyte may be used.

[0063] In one embodiment, the molar ratio of lithium (Li) to phosphorus (P) in the sulfide-based solid electrolyte ([Li] / [P]) may be 5.60 to 6.07, specifically 5.80 to 6.06. When the molar ratio of lithium (Li) to phosphorus (P) satisfies the above range, the ionic conductivity of the sulfide-based solid electrolyte is improved, which may lead to improved electrochemical stability and increased charge / discharge efficiency during the manufacture of an all-solid-state battery. On the other hand, if the molar ratio of lithium (Li) to phosphorus (P) is too low, problems may arise such as a decrease in the ionic conductivity of the sulfide-based solid electrolyte and a reduction in the mobility of lithium ions. Additionally, if the molar ratio of lithium (Li) to phosphorus (P) is too high, problems may arise such as reduced safety due to structural instability caused by excessive lithium and an increased possibility of electrolyte decomposition.

[0064] In one embodiment, the molar ratio of sulfur (S) to phosphorus (P) in the sulfide-based solid electrolyte ([S] / [P]) may be 4.60 to 5.07, specifically 4.80 to 5.04. When the molar ratio of sulfur (S) to phosphorus (P) satisfies the above range, a stable crystal structure is formed, which may have the advantage of improving the stability of the sulfide-based solid electrolyte. On the other hand, if the molar ratio of sulfur (S) to phosphorus (P) is too low, the ionic conductivity of the sulfide-based solid electrolyte may decrease, and problems such as an unstable crystal structure may occur. In addition, if the molar ratio of sulfur (S) to phosphorus (P) is too high, problems such as a decrease in the characteristics of the sulfide-based solid electrolyte and the performance of the all-solid-state battery may occur due to excessive sulfur content.

[0065] In one embodiment, the molar ratio of oxygen (O) to phosphorus (P) in the sulfide-based solid electrolyte ([O] / [P]) may be 0.120 to 1.690, specifically 0.123 to 1.610. When the molar ratio of oxygen (O) to phosphorus (P) satisfies the above range, the electrochemical stability of the solid electrolyte is improved, and the interfacial resistance between the electrode and the electrolyte is lowered, thereby improving the performance of the battery. On the other hand, if the molar ratio of oxygen (O) to phosphorus (P) is too low, problems may arise such as reduced stability of the solid electrolyte and decreased ionic conductivity. Additionally, if the molar ratio of oxygen (O) to phosphorus (P) is too high, the structure of the solid electrolyte may be deformed due to excessive oxygen, and self-discharge problems may occur due to increased electron conductivity.

[0066] In one embodiment, the molar ratio ([D] / [P]) of two or more halogen elements (D) to phosphorus (P) in the sulfide-based solid electrolyte may be 1.0 to 1.4, specifically 1.0 to 1.2. When the molar ratio of two or more halogen elements (D) to phosphorus (P) satisfies the above range, the thermal stability of the solid electrolyte is improved and the interfacial resistance is reduced, thereby improving the performance of the all-solid-state battery. On the other hand, if the molar ratio of two or more halogen elements (D) to phosphorus (P) is too low, the distribution of halogen elements within the sulfide-based solid electrolyte becomes non-uniform due to insufficient halogen doping, which may result in local performance differences. In addition, if the molar ratio of two or more halogen elements (D) to the phosphorus (P) is too high, the halogen elements may be excessively doped, which may reduce the structural stability of the solid electrolyte and cause a decrease in battery performance due to side reactions with the electrode material.

[0067] In one embodiment, the sulfide-based solid electrolyte may be represented by the following chemical formula 1.

[0068] [Chemical Formula 1]

[0069] Li(xy-x-5y+7)P (1-y) S (xy-x-5y+6) O 4y Cl(x-xy)(1-z)F z

[0070] In the above chemical formula 1, 1≤x≤2, 0.01≤y≤0.3, and 0.01≤z≤0.3.

[0071]

[0072] Method for manufacturing sulfide-based solid electrolytes

[0073] A method for manufacturing a sulfide-based solid electrolyte according to another embodiment of the present invention comprises: a step of preparing two or more types of raw materials, such as a lithium compound, a phosphorus compound, and a halogen compound; a step of mixing a doping material with the raw materials to form a mixture; and a step of heat-treating the mixture to form a sulfide-based solid electrolyte having an azirodite-based crystal structure.

[0074] In another embodiment, the heat treatment temperature may be 300 to 490°C, specifically 350 to 450°C. When the heat treatment temperature satisfies the above range, the azirodite crystal structure of the sulfide-based solid electrolyte is properly formed, which improves structural stability and removes unnecessary components, thereby improving purity. On the other hand, if the heat treatment temperature is too low, incomplete crystallization may occur during the manufacture of the sulfide-based solid electrolyte, and a problem of reduced ionic conductivity may occur. In addition, if the heat treatment temperature is too high, problems such as structural instability or the formation of other crystal phases may occur.

[0075] In another embodiment, the halogen compound may include at least two of LiCl, LiF, LiBr, and LiI, but is not limited thereto, and any material capable of improving the moisture stability and ionic conductivity of the sulfide-based solid electrolyte may be used.

[0076] In another embodiment, the amount of LiCl added may be 0.049 to 1.96 mol% based on the total moles of the mixture, specifically 0.08 to 1.5 mol%. If the amount of LiCl added satisfies the above range, the crystal structure of the solid electrolyte may be improved, the ion transport pathway may be made more efficient, interfacial resistance may be reduced, and electrochemical stability may be improved. On the other hand, if the amount of LiCl added is too small, the content in the sulfide-based solid electrolyte may be too low, so the improvement in ion conductivity may not be sufficient. In addition, if the amount of LiCl added is too large, structural instability of the solid electrolyte may occur due to excessive LiCl, and problems such as deterioration of the mechanical properties of the electrolyte may occur.

[0077] In another embodiment, the amount of LiF added may be 0.01 to 0.3 mol% based on the total mixture, specifically 0.05 to 0.25 mol%. When the amount of LiF added satisfies the above range, the movement of lithium ions within the sulfide-based solid electrolyte is promoted, thereby improving ion conductivity and increasing the charge-discharge cycle life of the all-solid-state battery. On the other hand, if the amount of LiF added is too small, the amount of LiF in the sulfide-based solid electrolyte is too small, so the effect of improving ion conductivity may be insufficient. In addition, if the amount of LiF added is too large, the structural stability of the solid electrolyte may be reduced due to the excessive LiF, and unnecessary side reactions may occur.

[0078] All-solid-state battery

[0079] Another embodiment of the present invention provides an all-solid-state battery comprising: an anode layer; a cathode layer; and a solid electrolyte layer located between the anode layer and the cathode layer, wherein at least one of the anode layer, the cathode layer, and the solid electrolyte layer comprises the aforementioned solid electrolyte.

[0080] (Bipolar layer)

[0081] More specifically, the anode layer may include an anode current collector and an anode active material layer disposed on the anode current collector.

[0082] The above-mentioned positive active material layer may further include, for example, a positive active material and, optionally, a solid electrolyte. The solid electrolyte included in the positive 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.

[0083] The cathode active material is a material capable of reversibly absorbing and desorbing lithium ions. The cathode active material may be, for example, 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, but is not necessarily limited to these; any material used as a cathode active material in the relevant technical field is acceptable. The cathode active material may be a single material or a mixture of two or more materials.

[0084] The above lithium transition metal oxide is, for example, Li a A 1-b B b D2(wherein 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-b B b O 4-c D c(In the above equation, 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(wherein 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(wherein 0.90 ≤ a ≤ 1, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, 0 < α < 2); Li a Ni b E c G dO2(wherein 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(wherein 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 equation, 0.90 ≤ a ≤ 1, 0.001 ≤ b ≤ 0.1); Li a CoG b O2(in the above equation, 0.90 ≤ a ≤ 1, 0.001 ≤ b ≤ 0.1); Li a MnG b O2(in the above equation, 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 such a 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; and J is V, Cr, Mn, Co, Ni, Cu, or a combination thereof. A compound having a coating layer added to the surface of such a compound may also be used, and a mixture of the compound described above and a compound having a coating layer added may also be used. The coating layer applied to the surface of such compounds comprises, for example, a coating element compound of an oxide, hydroxide, oxyhydroxide, oxycarbonate, or hydroxycarbonate of a coating element. The compounds forming this coating layer are 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 mixtures thereof. The method for forming the coating layer is selected within a range that does not adversely affect the physical properties of the cathode active material. The coating method is, for example, spray coating or immersion. Since specific coating methods are well understood by those skilled in the art, a detailed explanation will be omitted.

[0085] The positive active material layer may include, for example, a binder. The binder may be, for example, styrene butadiene rubber (SBR), polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, etc., but is not limited to these, and any binder used in the relevant technical field is acceptable.

[0086] The positive active material layer may include, for example, a conductive material. The conductive material may include, for example, graphite, carbon black, acetylene black, Ketjen black, carbon fiber, metal powder, etc., but is not limited to these, and any material used as a conductive material in the relevant technical field is acceptable.

[0087] The positive active material layer may further include additives such as fillers, coating agents, dispersants, and ion conductivity aids in addition to the positive active material, solid electrolyte, binder, and conductive material described above, for example.

[0088] As fillers, coating agents, dispersants, ion conductivity aids, etc. that may be included in the positive electrode active material layer, known materials generally used in electrodes of all-solid-state secondary batteries can be used.

[0089] The positive current collector may be a plate or foil made of, for example, 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 alloys thereof. The thickness of the positive current collector may be, for example, 1 µm to 100 µm, 1 µm to 50 µm, 5 µm to 25 µm, or 10 µm to 20 µm.

[0090] (Cathode layer)

[0091] More specifically, the above cathode layer may include a cathode current collector and a cathode active material layer disposed on the cathode current collector.

[0092] The above-mentioned cathode active material layer may include, for example, a cathode active material and a binder, and may optionally further include a solid electrolyte as needed.

[0093] The above-mentioned negative electrode active material may include, for example, a carbon-based negative electrode active material, a metal / metallic negative electrode active material, or a combination thereof.

[0094] The carbon-based cathode 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), Kettjen black (KB), graphene, etc., but is not necessarily limited to these, and any material classified as amorphous carbon in the relevant technical field is acceptable. Amorphous carbon is carbon that does not have crystallinity or has very low crystallinity, and is distinguished from crystalline carbon or graphite-based carbon. The crystalline carbon may be, for example, natural graphite, artificial graphite, or a combination thereof.

[0095] The metal / metallic anode active material comprises one or more 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 to these, and any metal anode active material or metallic anode active material that forms an alloy or compound with lithium in the relevant technical field is acceptable.

[0096] 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 to these, and any binder used in the relevant technical field is acceptable. The binder may be composed of a single binder or a plurality of different binders.

[0097] The cathode active material layer is stabilized on the cathode current collector by including a binder. In addition, cracking of the cathode active material layer is suppressed despite volume changes and / or relative positional changes of the cathode active material layer during the charging and discharging process.

[0098] The negative electrode active material layer may further include additives used in conventional all-solid-state batteries, such as fillers, coating agents, dispersants, ion conductivity aids, etc.

[0099] 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 upon 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. This second negative electrode active material layer may be a metal layer comprising lithium or a lithium alloy. The lithium alloy may be, for example, 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, but is not limited thereto; any alloy used as a lithium alloy in the relevant technical field is acceptable. The second negative electrode active material layer may be composed of one of these alloys and / or lithium, or may be composed of various types of alloys and / or lithium.

[0100] The negative electrode current collector may be composed of, for example, a material that does not react with lithium, that is, does not form either an alloy or a compound. The negative electrode current collector may include, for example, copper (Cu), stainless steel, titanium (Ti), iron (Fe), cobalt (Co), and nickel (Ni), but is not necessarily limited to these; any material used as an electrode current collector in the relevant technical field is acceptable. The negative electrode current collector may be composed of one of the metals described above, or may be composed of an alloy or coating material of two or more metals. The negative electrode current collector may be, for example, in the form of a plate or a foil.

[0101] When the above-mentioned cathode active material layer includes a solid electrolyte, the solid electrolyte included in the above-mentioned cathode 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.

[0102] (Solid electrolyte layer)

[0103] The above solid electrolyte layer can be manufactured by mixing and drying the aforementioned solid electrolyte and binder, or by rolling the aforementioned solid electrolyte powder into a certain shape under a pressure of 1 ton to 10 ton.

[0104] At this time, the solid electrolyte may be in the form of a powder or a molded article. The solid electrolyte in the form of a molded article may be, for example, in the form of pellets, sheets, thin films, etc., but is not necessarily limited to these and may have various forms depending on the application.

[0105] The above solid electrolyte layer may, if necessary, further include a solid electrolyte such as a conventional sulfide-based solid electrolyte and / or an oxide-based solid electrolyte in addition to the aforementioned solid electrolyte.

[0106] The above binder is, for example, styrene butadiene rubber (SBR), polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polyvinyl alcohol, etc., but is not limited to these, and any binder used in the relevant technical field is acceptable. The binder of the solid electrolyte layer may be of the same type as or different from the binders of the anode layer and the cathode layer.

[0107] Another embodiment of the present invention provides an electric vehicle comprising the all-solid-state battery.

[0108] The embodiments of the present invention will be described in more detail below through examples. However, the following examples are merely preferred embodiments of the present invention, and the present invention is not limited by the following examples.

[0109] Example 1

[0110] 1-1. Li 5.88 P 0.97 S 4.88 O 0.12 Cl 0.96 F 0.01 Method for manufacturing sulfide-based solid electrolytes

[0111] Li(xy-x-5y+7)P (1-y) S (xy-x-5y+6) O 4y Cl(x-xy)(1-z)F z After quantifying Li2S, P2S5, LiCl, Li3PO4, and LiF in a solid electrolyte with x: 1.0, y: 0.03, and z: 0.01, the mixture was mixed at 300 rpm for approximately 8 hours using a planetary mill, pellets were prepared at 300 MPa, and the product was manufactured through heat treatment at 430°C in an Ar atmosphere.

[0112] 1-2. Method for manufacturing an all-solid-state battery

[0113] 75 wt% of cathode active material and the sulfide-based solid electrolyte with an Argyrodite crystal structure of Example 1-1 (Li 5.88 P 0.97 S 4.88 O 0.12 Cl 0.96 F 0.01 ) 22wt%, Super C as a conductive agent 65 A mixed paste was prepared by thoroughly mixing 3 wt% with a solvent containing a small amount of dissolved binder. An electrode plate was manufactured using the mixed paste and dried to produce a composite electrode plate for the anode. First, an Argyrodite solid electrolyte (Li₂) functioning as a separator was placed in a jig for all-solid-state battery evaluation. 4.8 P 0.7 S 3.8 O 1.2 Cl 0.693 F 0.01 100 mg of ) was loaded, and after applying pressure of 300 MPa or more to achieve a thickness of approximately 800 μm, a positive electrode plate was placed on one side and a secondary pressure was applied to fabricate the positive electrode. Subsequently, a Li-In alloy was placed on the other side and an appropriate pressure was applied to fabricate a battery for all-solid-state battery evaluation.

[0114] Example 2

[0115] 2-1. Li 5.88 P 0.97 S 4.88 O 0.12 Cl 0.94 F 0.03 Method for manufacturing sulfide-based solid electrolytes

[0116] Li(xy-x-5y+7)P (1-y) S (xy-x-5y+6) O 4y Cl(x-xy)(1-z)F z It was prepared in the same manner as Example 1-1, except that x: 1.0, y: 0.03, and z: 0.03 were applied to the solid electrolyte.

[0117] 2-2. Method for Manufacturing All-Solid State Batteries

[0118] Sulfide-based solid electrolyte (Li of Example 2-1) 5.88 P0.97 S 4.88 O 0.12 Cl 0.94 F 0.03 It was prepared in the same manner as Example 1-2, except that ) was used.

[0119] Example 3

[0120] 3-1. Li 5.88 P 0.97 S 4.88 O 0.12 Cl 0.922 F 0.05 Method for manufacturing sulfide-based solid electrolytes

[0121] Li(xy-x-5y+7)P (1-y) S (xy-x-5y+6) O 4y Cl(x-xy)(1-z)F z It was prepared in the same manner as Example 1-1, except that x: 1.0, y: 0.03, and z: 0.05 were applied to the solid electrolyte.

[0122] 3-2. Method for manufacturing all-solid-state batteries

[0123] Sulfide-based solid electrolyte (Li of Example 3-1) 5.88 P 0.97 S 4.88 O 0.12 Cl 0.922 F 0.05 It was prepared in the same manner as Example 1-2, except that ) was used.

[0124] Comparative Example 1

[0125] 1-1. Li6PS5Cl Method for manufacturing sulfide-based solid electrolytes

[0126] Li(xy-x-5y+7)P (1-y) S (xy-x-5y+6) O 4y Cl(x-xy)(1-z)F z It was prepared in the same manner as Example 1-1, except that x: 1.0, y: 0, and z: 0 were applied to the solid electrolyte.

[0127] 1-2. Method for manufacturing an all-solid-state battery

[0128] It was prepared in the same manner as Example 1-2, except that the sulfide-based solid electrolyte (Li6PS5Cl) of Comparative Example 1-1 was used.

[0129] Comparative Example 2

[0130] 2-1. Li 5.96 P 0.99 S 4.96 O 0.04 Cl 0.99 Method for manufacturing sulfide-based solid electrolytes

[0131] Li(xy-x-5y+7)P (1-y) S (xy-x-5y+6) O 4y Cl(x-xy)(1-z)F z It was prepared in the same manner as Example 1-1, except that x: 1.0, y: 0.01, and z: 0 were applied to the solid electrolyte.

[0132] 2-2. Method for Manufacturing All-Solid State Batteries

[0133] Sulfide-based solid electrolyte (Li of Comparative Example 2-1) 5.96 P 0.99 S 4.96 O 0.04 Cl 0.99 It was prepared in the same manner as Example 1-2, except that ) was used.

[0134] Comparative Example 3

[0135] 3-1. Li 5.88 P 0.97 S 4.88 O 0.12 Cl 0.97 Method for manufacturing sulfide-based solid electrolytes

[0136] Li(xy-x-5y+7)P (1-y) S (xy-x-5y+6) O 4y Cl(x-xy)(1-z)F z It was prepared in the same manner as Example 1-1, except that x: 1.0, y: 0.03, and z: 0 were applied to the solid electrolyte.

[0137] 3-2. Method for manufacturing all-solid-state batteries

[0138] Sulfide-based solid electrolyte (Li of Comparative Example 3-1)5.88 P 0.97 S 4.88 O 0.12 Cl 0.97 It was prepared in the same manner as Example 1-2, except that ) was used.

[0139] Comparative Example 4

[0140] 4-1. Li 5.8 P 0.95 S 4.8 O 0.2 Cl 0.95 Method for manufacturing sulfide-based solid electrolytes

[0141] Li(xy-x-5y+7)P (1-y) S (xy-x-5y+6) O 4y Cl(x-xy)(1-z)F z It was prepared in the same manner as Example 1-1, except that x: 1.0, y: 0.05, and z: 0 were applied to the solid electrolyte.

[0142] 4-2. Method for manufacturing all-solid-state batteries

[0143] Sulfide-based solid electrolyte (Li of Comparative Example 4-1) 5.8 P 0.95 S 4.8 O 0.2 Cl 0.95 It was prepared in the same manner as Example 1-2, except that ) was used.

[0144] Comparative Example 5

[0145] 5-1. Li 5.6 P 0.9 S 4.6 O 0.4 Cl 0.9 Method for manufacturing sulfide-based solid electrolytes

[0146] Li(xy-x-5y+7)P (1-y) S (xy-x-5y+6) O 4y Cl(x-xy)(1-z)F z It was prepared in the same manner as Example 1-1, except that x: 1.0, y: 0.1, and z: 0 were applied to the solid electrolyte.

[0147] 5-2. Method for manufacturing all-solid-state batteries

[0148] Sulfide-based solid electrolyte (Li of Comparative Example 5-1) 5.6 P 0.9 S 4.6 O 0.4 Cl 0.9 It was prepared in the same manner as Example 1-2, except that ) was used.

[0149] Comparative Example 6

[0150] 6-1. Li 4.8 P 0.7 S 3.8 O 1.2 Cl 0.7 Method for manufacturing sulfide-based solid electrolytes

[0151] Li(xy-x-5y+7)P (1-y) S (xy-x-5y+6) O 4y Cl(x-xy)(1-z)F z It was prepared in the same manner as Example 1-1, except that x: 1.0, y: 0.3, and z: 0 were applied to the solid electrolyte.

[0152] 6-2. Method for Manufacturing All-Solid State Batteries

[0153] Sulfide-based solid electrolyte (Li of Comparative Example 6-1) 4.8 P 0.7 S 3.8 O 1.2 Cl 0.7 It was prepared in the same manner as Example 1-2, except that ) was used.

[0154] Experimental Example 1: 31 P-NMR Nuclear Magnetic Resonance Evaluation

[0155] Nuclear magnetic resonance evaluation experiments were conducted on sulfide-based solid electrolytes having an azirodite-based crystal structure prepared according to the examples and comparative examples. The specific experimental methods are as follows.

[0156] person( 31The nuclear magnetic resonance spectrum of P-NMR was obtained using the Magic Angle Rotation (MAS) technique with a Bruker Avance NEO 500 MHz spectrometer equipped with a 4 mm triple resonance probe having a maximum magic angle rotation speed of 15 kHz, and the results are shown in Table 1.

[0157] Experimental Example 2: Evaluation of Ionic Conductivity (30℃, 0.1C)

[0158] An experiment to evaluate the ionic conductivity of a solid electrolyte was conducted using a pressure powder cell. Specifically, the synthesized solid electrolyte was ground and then formed into pellets under a pressure of 300 MPa. Subsequently, a cell was fabricated using SUS as the working electrode under a pressure of 70 MPa. Then, the impedance was measured by applying a voltage of 10 mV at 25°C, and the results are shown in Table 2.

[0159] Experimental Example 3: Evaluation of Electrochemical Properties

[0160] (1) Discharge capacity evaluation

[0161] An initial discharge capacity evaluation experiment was conducted when the sulfide-based solid electrolytes prepared according to the examples and comparative examples were applied to batteries. The specific experimental method is as follows.

[0162] Electrochemical evaluations of the solid electrolytes prepared in the Comparative and Examples were conducted using a pressure powder cell. The composite anode electrode had an anode : solid electrolyte : conductive material (Denka Black) ratio of 70 : 29 : 1 wt% and a diameter of 0.785 cm 2Electrodes were fabricated with a loading of 20.0 mg over an area and densified to 300 MPa. Subsequently, bonding was performed at 50 MPa using an Indium-Lithium counter electrode, and the cells were assembled under the same pressure. After fabrication, charge and discharge tests were conducted after aging at room temperature for 2 hours. Capacity evaluation was performed using 180 mAh / g as the reference capacity, and charge / discharge conditions were applied at CC / CV 1.9 to 3.60 V and a 1 / 20C cut-off. Initial capacity was evaluated under 0.1C charge / 0.1C discharge conditions, and the results are shown in Table 2.

[0163] (2) Life characteristic evaluation (30℃, 100 cycles)

[0164] Lifetime characteristics were evaluated when the sulfide-based solid electrolytes prepared according to the examples and comparative examples were applied to batteries. The specific experimental methods are as follows.

[0165] After fabricating the battery half cell, it was charged to 3.63V at 30℃ with a constant current of 0.5C, then switched to a constant voltage and charged until the terminal current reached 0.1C. After a rest time of 10 minutes following charging, it was discharged with a constant current of 0.5C until it reached 1.9V. 100 charge-discharge cycles were performed under these conditions, and the capacity retention rate of the 100th cycle compared to the first cycle was calculated, and the results are shown in Table 2.

[0166] Intensity 31 P-MAS NMR ABCC / AC / B Comparative Example 190334572375464630130111.003.341.26838813 Example 161245352212825242376858.006.921.91505673

[0167] Referring to Table 1, it can be seen that the C / A of Example 1, which contains phosphorus and heterogenous halogen elements, is 6.92, and the C / A of Comparative Example 1 is 3.34. Referring to Fig. 1, it can be seen that the sulfide-based solid electrolyte of Example 1 has an azirodite-based crystal structure, as A of Example 1 includes a peak range of 85 to 87 ppm, B includes a peak range of 83 to 85 ppm, and C includes a peak range of 82 to 83 ppm.

[0168] xyzLiPSOHa Ion Conductivity Discharge Capacity 100 Cycles ClF (d) mS / cmmAh g -1 Lifespan Comparison Example 1 1006 150102.1 20784 Comparison Example 2 10.0105.96 0.994.96 0.04 0.9902 20986 Comparison Example 3 10.0305.88 0.974.88 0.1 20.9701.9 20886 Comparison Example 4 10.0505.80.954.80.2 0.9501.7 20587 Comparison Example 5 10.105.6 0.94.6 0.4 0.901.5 19985 Comparative Example 6 10.304.80.73.81.20.701.119284 Example 1 10.030.015.880.974.880.120.960.011.8021187 Example 2 10.030.035.880.974.880.120.940.031.921387 Example 3 10.030.055.880.974.880.120.9220.051.921185

[0169] Referring to Table 2, it can be confirmed that the ionic conductivity of the solid electrolytes of Examples 1 to 3 containing halogen elements P, Cl, and F does not deteriorate compared to Comparative Examples 1 to 6, and that the electrochemical properties are excellent when manufacturing all-solid-state batteries. Although preferred embodiments of the present invention have been described above, the present invention is not limited thereto and can be implemented with various modifications within the scope of the claims, the detailed description of the invention, and the attached drawings, and it is obvious that such modifications also fall within the scope of the present invention.

[0170] Therefore, the substantive scope of the present invention shall be defined by the appended claims and their equivalents.

Claims

In a sulfide-based solid electrolyte comprising lithium (Li), phosphorus (P), oxygen (O), sulfur (S) and two or more halogen elements, The above sulfide-based solid electrolyte has an azirodite-based crystal structure, and of the above sulfide-based solid electrolyte 31 A sulfide-based solid electrolyte whose P-NMR spectrum satisfies the following Equation 1: [Equation 1] C / A≥3.5 In the above Equation 1, A represents the peak area appearing at 85 to 87 ppm, and C represents the peak area appearing at 82 to 83 ppm. In paragraph 1, of the above sulfide-based solid electrolyte 31 A sulfide-based solid electrolyte whose P-NMR spectrum satisfies the following Equation 2: [Equation 2] 3.5≤C / A≤10 In the above Equation 2, A and C are as defined in the above Equation 1. In paragraph 1, of the above sulfide-based solid electrolyte 31 A sulfide-based solid electrolyte whose P-NMR spectrum satisfies Equation 3 below: [Equation 3] 1.3≤C / B≤10 In the above Equation 3, B represents the area of ​​the peak appearing at 83 to 85 ppm, and C represents the area of ​​the peak appearing at 82 to 83 ppm. In paragraph 1, The above halogen element comprises at least two of Cl, Br, I, and F, in a sulfide-based solid electrolyte. In paragraph 1, The above sulfide-based solid electrolyte is a sulfide-based solid electrolyte having a molar ratio of lithium (Li) to phosphorus (P) ([Li] / [P]) of 5.60 to 6.

07. In paragraph 1, The above sulfide-based solid electrolyte is a sulfide-based solid electrolyte having a molar ratio of sulfur (S) to phosphorus (P) ([S] / [P]) of 4.60 to 5.

07. In paragraph 1, The above sulfide-based solid electrolyte is a sulfide-based solid electrolyte having a molar ratio of oxygen (O) to phosphorus (P) ([O] / [P]) of 0.12 to 1.

69. In paragraph 1, The above sulfide-based solid electrolyte is a sulfide-based solid electrolyte in which the molar ratio ([D] / [P]) of two or more halogen elements (D) to phosphorus (P) is 1.0 to 1.

4. In paragraph 1, The above sulfide-based solid electrolyte is a sulfide-based solid electrolyte represented by the following chemical formula 1: [Chemical Formula 1] Li(xy-x-5y+7)P (1-y) S (xy-x-5y+6) O 4y Cl(x-xy)(1-z)F z In the above chemical formula 1, 1≤x≤2, 0.01≤y≤0.3, and 0.01≤z≤0.

3. A step of preparing two or more types of raw materials, including lithium compounds, phosphorus compounds, and halogen compounds; A step of forming a mixture by mixing a doping substance with the above raw material; and A method for manufacturing a sulfide-based solid electrolyte, comprising the step of heat-treating the above mixture to form a sulfide-based solid electrolyte having an azirodite-based crystal structure. In Paragraph 10, A method for manufacturing a sulfide-based solid electrolyte, wherein the heat treatment temperature is 300 to 490℃. In Paragraph 10, A method for preparing a sulfide-based solid electrolyte, wherein the above halogen compound comprises at least two of LiCl, LiF, LiBr, and LiI. In Paragraph 12, A method for manufacturing a sulfide-based solid electrolyte, wherein the amount of LiCl added is 0.049 to 1.96 mol% based on the total molar amount of the mixture. In Paragraph 12, A method for manufacturing a sulfide-based solid electrolyte, wherein the amount of LiF added is 0.01 to 0.3 mol% based on the total mixture. anode layer; cathode layer; and It includes a solid electrolyte layer disposed between the anode layer and the cathode layer, and An all-solid-state battery comprising one or more of the anode layer, cathode layer, and solid electrolyte layer, wherein the anode layer, cathode layer, and solid electrolyte layer comprise a sulfide-based solid electrolyte according to any one of claims 1 to 9.

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