Solid electrolyte

Abstract

The present invention relates to a solid electrolyte comprising: a sulfide-based lithium ion conductive compound; and a coating layer surrounding the entire surface of the sulfide-based lithium ion conductive compound in the form of a thin film and containing an aluminum compound, wherein, in X-ray photoelectron spectroscopy (XPS) analysis, a first peak appears in a region with a binding energy of 73 to 74 eV and a second peak appears in a region with a binding energy of 75 to 76 eV.

Description

solid electrolyte

[0001] This application claims priority to Korean Patent Application No. 10-2024-0189871 filed on December 18, 2024, and the contents of said priority application are all incorporated into this specification.

[0002] The present invention relates to a solid electrolyte, a method for manufacturing the same, and an all-solid-state battery comprising the same.

[0003] As research on the safety issues and energy density of high-capacity batteries gains attention, all-solid-state batteries are being hailed as the next generation of batteries.

[0004] The above-described all-solid-state battery is a battery that ensures safety by replacing the liquid electrolyte, which causes explosions, with a solid electrolyte, thereby eliminating the use of flammable solvents within the battery and preventing any ignition or explosion caused by reactions such as the decomposition reaction of conventional electrolytes.

[0005] In addition, since lithium metal or lithium alloy can be used as the cathode material, the energy density relative to the mass and volume of the battery can be improved.

[0006] Inorganic solid electrolytes are generally used as the solid electrolytes in the aforementioned all-solid-state batteries, and various studies are currently underway regarding sulfide-based solid electrolytes having a composition such as Li6PS5Cl, which has an argyrodite structure, among the aforementioned all-solid-state batteries.

[0007] Although azirodite-based sulfide solid electrolytes possess high lithium ion conductivity, they have a problem with poor moisture stability, such as a sharp decrease in ion conductivity due to the sensitive reaction of sulfur (S) among their constituent elements with atmospheric moisture.

[0008]

[0009] Accordingly, one objective of the present invention is to provide a solid electrolyte with improved moisture stability, a method for manufacturing the same, and an all-solid-state battery including the same.

[0010]

[0011] One embodiment of the present invention provides a solid electrolyte comprising: a sulfide-based lithium ion conductive compound; and a coating layer containing an aluminum compound that wraps the entire surface of the sulfide-based lithium ion conductive compound in the form of a thin film, wherein a first peak appears in a region where the binding energy is 73 to 74 eV and a second peak appears in a region where the binding energy is 75 to 76 eV during X-ray Photoelectron Spectroscopy (XPS) analysis.

[0012] The first peak above may be a peak derived from aluminum fluoride, and the second peak may be a peak derived from aluminum oxide.

[0013] The peak intensity ratio of the second peak to the first peak (second peak / first peak) may be 0.005 to 0.8.

[0014] The above aluminum compound may include AlF3 and Al2O3.

[0015] The coating layer may have an average thickness of 0.008 to 0.8 nm.

[0016] The aluminum content in the solid electrolyte may be 0.0008 to 0.3 weight% based on the total weight of the solid electrolyte.

[0017] The above sulfide-based lithium ion conductive compound may have an argyrodite-based crystal structure.

[0018] The above solid electrolyte may have an average particle size (D50) of 1.0 to 6.0 μm.

[0019]

[0020] Another embodiment of the present invention provides a solid electrolyte comprising: a sulfide-based lithium ion conductive compound; and a coating layer containing zinc fluoride that covers the entire surface of the sulfide-based lithium ion conductive compound in the form of a thin film.

[0021] The above zinc fluoride may include ZnF2.

[0022] The above coating layer may further contain zinc oxide.

[0023] The coating layer may have an average thickness of 0.005 to 1 nm.

[0024] The zinc content in the solid electrolyte may be 0.001 to 1 weight% based on the total weight of the solid electrolyte.

[0025] The above sulfide-based lithium ion conductive compound may have an argyrodite-based crystal structure.

[0026] The above solid electrolyte may have an average particle size (D50) of 1.0 to 6.0 μm.

[0027]

[0028] Another embodiment of the present invention provides a method for manufacturing a solid electrolyte comprising the steps of: preparing a sulfide-based lithium ion conductive compound; and forming a coating layer containing fluoride by covering the entire surface of the sulfide-based lithium ion conductive compound in the form of a thin film using an atomic layer deposition (ALD) method with a fluorine precursor and a metal precursor, wherein the metal precursor is aluminum alkoxide or zinc alkoxide.

[0029] The above atomic layer deposition can be performed in 2 to 120 cycles.

[0030] The above atomic layer deposition can be performed at a temperature of 20 to 100°C.

[0031] The above atomic layer deposition can be performed in an argon or nitrogen atmosphere.

[0032]

[0033] Another embodiment of the present invention provides an all-solid-state battery comprising the aforementioned solid electrolyte.

[0034]

[0035] In one embodiment of the present invention, the solid electrolyte comprises an aluminum compound-containing coating layer that wraps the entire surface of a sulfide-based lithium ion conductive compound in the form of a thin film, wherein moisture stability can be improved as different peaks are expressed in a specific binding energy region during XPS analysis.

[0036] A solid electrolyte according to another embodiment of the present invention may have improved moisture stability by including a zinc fluoride-containing coating layer that wraps the entire surface of a sulfide-based lithium ion conductive compound in the form of a thin film.

[0037]

[0038] Figure 1 is a graph of the XPS analysis results of the solid electrolyte prepared according to Example 2.

[0039] 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 present invention.

[0040] 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.

[0041] When it is stated that one part is "above" or "on" another part, it may be directly above or on the other part, or other parts may be involved in between. In contrast, when it is stated that one part is "directly above" another part, no other parts are interposed in between.

[0042] 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.

[0043] Also, unless otherwise specified, % means weight %, and 1 ppm is 0.0001 weight %.

[0044] 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.

[0045] 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.

[0046]

[0047] 1. Solid electrolyte

[0048] A solid electrolyte according to one embodiment of the present invention comprises a sulfide-based lithium ion conductive compound.

[0049] More specifically, the above-mentioned sulfide-based lithium ion conductive compound may have an argyrodite crystal structure. Accordingly, excellent ion conductivity can be achieved.

[0050] Whether a solid electrolyte has an azirodite-based crystal structure can be confirmed, for example, by XRD measurement. That is, in the X-ray diffraction pattern measured by an X-ray diffraction device (XRD) using CuKα1 rays, the crystal phase of the azirodite-based crystal structure has characteristic peaks at 2θ=15.34°±1.00°, 17.74°±1.00°, 25.19°±1.00°, 29.62°±1.00°, 30.97°±1.00°, 44.37°±1.00°, 47.22°±1.00°, and 51.70°±1.00°. In addition, for example, it has characteristic peaks at 2θ=54.26°±1.00°, 58.35°±1.00°, 60.72°±1.00°, 61.50°±1.00°, 70.46°±1.00°, and 72.61°±1.00°. Meanwhile, the fact that the solid electrolyte does not contain a crystal phase of an azirodite-based crystal structure can be confirmed by not having a characteristic peak of the crystal phase of the azirodite-based crystal structure described above.

[0051] The statement that a solid electrolyte has an azirodite-based crystal structure means that the solid electrolyte has at least a crystal phase of an azirodite-based crystal structure. In the present invention, it is preferable that the solid electrolyte has a crystal phase of an azirodite-based crystal structure as a main phase. At this time, "main phase" refers to the phase that has the largest proportion relative to the total amount of all crystal phases constituting the solid electrolyte. Accordingly, the content ratio of the crystal phase of an azirodite-based crystal structure contained in the solid electrolyte is preferably, for example, 60 mass% or more relative to the total crystal phases constituting the solid electrolyte, and among them, it is more preferable to have 70 mass% or more, 80 mass% or more, or 90 mass% or more. In addition, the ratio of the crystal phase can be confirmed, for example, by XRD.

[0052] Meanwhile, the lithium ion conductive compound having the azirodite crystal structure described above may include basic elements Li, P, S, and halogen elements, and may optionally include other doping elements as needed.

[0053] The above other doping elements may be, for example, Si, Al, In, Zr, B, Na, Mg, Ca, Ge, Ga, Zn, Sn, O, or combinations thereof. The amount of the above other doping elements introduced can be appropriately adjusted according to the purpose within a range that does not degrade the electrochemical properties of the solid electrolyte.

[0054] However, although sulfide-based lithium ion conductive compounds exhibit excellent ion conductivity immediately after synthesis, there is a problem in which ion conductivity rapidly deteriorates—that is, moisture stability is reduced—because sulfur among the constituent elements reacts with atmospheric moisture, causing the crystal structure to degrade.

[0055] Accordingly, the solid electrolyte according to the present invention comprises a coating layer containing a compound of a specific composition that wraps the entire surface of a sulfide-based lithium ion conductive compound in the form of a thin film. Accordingly, the moisture stability of the solid electrolyte according to the present invention can be improved.

[0056]

[0057] In one embodiment, a solid electrolyte is provided comprising: a sulfide-based lithium ion conductive compound; and a coating layer containing an aluminum compound that wraps the entire surface of the sulfide-based lithium ion conductive compound in the form of a thin film, wherein a first peak appears in a region where the binding energy is 73 to 74 eV and a second peak appears in a region where the binding energy is 75 to 76 eV during X-ray Photoelectron Spectroscopy (XPS) analysis.

[0058] The first peak above may be a peak derived from aluminum fluoride, and the second peak may be a peak derived from aluminum oxide.

[0059] That is, the aluminum compound may include both aluminum fluoride and aluminum oxide. Since aluminum fluoride has hydrophobic properties, it can improve the moisture stability of the solid electrolyte by blocking contact between the substrate and moisture in the atmosphere. Since aluminum oxide has excellent lithium ion conductivity, it can minimize the degradation of lithium ion conductivity due to the coating. In other words, the solid electrolyte according to one embodiment of the present invention includes a coating layer containing both aluminum fluoride and aluminum oxide, thereby improving moisture stability without significant degradation of lithium ion conductivity.

[0060] More specifically, the aluminum compound may include AlF3 as aluminum fluoride and Al2O3 as aluminum oxide. The specific composition of the aluminum compound within this coating layer can be confirmed through X-ray Photoelectron Spectroscopy (XPS) analysis of the surface of the solid electrolyte particles.

[0061] Meanwhile, the composition of a coating layer containing both aluminum fluoride and aluminum oxide can be realized by using aluminum alkoxide as an aluminum precursor, as described in the manufacturing method to be described later. This will be explained in more detail in the manufacturing method to be described later.

[0062] At this time, the peak intensity ratio of the second peak to the first peak (second peak / first peak) may be 0.005 to 0.8, and more specifically, 0.1 to 0.24. When the peak intensity ratio of the second peak to the first peak satisfies the above range, the content of aluminum fluoride, which causes a moisture stability improvement effect, and aluminum oxide, which causes a lithium ion conductivity degradation prevention effect, can be appropriately controlled. Accordingly, the moisture stability improvement effect and the lithium ion conductivity degradation prevention effect can be more preferably realized.

[0063] In addition, the coating layer may have an average thickness of 0.008 to 0.8 nm, and more specifically, 0.03 to 0.2 nm. If the average thickness of the coating layer is too thin, the effect of improving the moisture stability of the solid electrolyte by coating the coating layer may be negligible. If the average thickness of the coating layer is too thick, moisture stability is improved, but the ionic conductivity of the solid electrolyte may deteriorate too much. Therefore, when the average thickness of the coating layer satisfies the above range, moisture stability and ionic conductivity of the solid electrolyte can be desirablely achieved simultaneously.

[0064] The average thickness of the coating layer can be measured by the following method. First, the coating layer thickness for a single solid electrolyte particle can be obtained by observing the solid electrolyte particle with a TEM (transmission electron microscope) image and deriving the average value of the thickness for 10 measurement regions along the entire perimeter of the solid electrolyte particle. Next, the average thickness of the coating layer can be obtained by deriving the average value of the coating layer thickness obtained by the same method as above for any 20 solid electrolyte particles among the solid electrolyte powders.

[0065] In addition, the aluminum content in the solid electrolyte may be 0.0008 to 0.3 weight% based on the total weight of the solid electrolyte, and more specifically, 0.008 to 0.03 weight%. If the aluminum content is too low, a sufficient coating layer is not formed, so the effect of improving moisture stability may be negligible. If the aluminum content is too high, the coating layer is excessively formed, which may degrade the ionic conductivity of the solid electrolyte. Therefore, when the aluminum content satisfies the above range, the moisture stability and ionic conductivity of the solid electrolyte can be desirablely achieved simultaneously.

[0066] Meanwhile, the above coating layer can conformally cover the entire surface of the sulfide-based lithium ion conductive compound in the form of a thin film. Accordingly, the effect of blocking contact between the solid electrolyte and atmospheric moisture can be maximized, thereby more preferably realizing the effect of improving moisture stability. Meanwhile, the implementation of the conformal coating layer in the form of a thin film can be achieved through an Atomic Layer Deposition (ALD) vapor phase method, as described in the manufacturing method to be described later. This will be explained in more detail in the manufacturing method to be described later.

[0067]

[0068] In another embodiment, a solid electrolyte is provided comprising: a sulfide-based lithium ion conductive compound; and a coating layer containing zinc fluoride that covers the entire surface of the sulfide-based lithium ion conductive compound in the form of a thin film.

[0069] In this case, the zinc fluoride may more specifically include ZnF2. Additionally, the coating layer may further contain zinc oxide. By having the coating layer contain zinc fluoride and further containing zinc oxide, the moisture stability of the solid electrolyte can be improved, while the deterioration of ion conductivity can be minimized. The technical principle is the same as the description of the aluminum compound-containing coating layer mentioned earlier, so it is omitted.

[0070] More specifically, the zinc oxide may include ZnO.

[0071] The specific composition of zinc compounds within these coating layers can be confirmed through X-ray Photoelectron Spectroscopy (XPS) analysis of the surface of solid electrolyte particles.

[0072] In addition, the average thickness of the coating layer may be 0.005 to 1 nm, and more specifically, 0.03 to 0.3 nm. When the average thickness of the coating layer satisfies the above range, the moisture stability and ion conductivity of the solid electrolyte can be preferably realized simultaneously. The technical principle thereof is the same as the description of the aluminum compound-containing coating layer above, so it is omitted.

[0073] In addition, the zinc content in the solid electrolyte may be 0.001 to 1 weight% based on the total weight of the solid electrolyte, and more specifically, 0.01 to 0.2 weight% or 0.02 to 0.1 weight%. When the zinc content satisfies the above range, the moisture stability and ionic conductivity of the solid electrolyte can be preferably achieved simultaneously. The technical principle thereof is the same as the description of the aluminum compound-containing coating layer above, so it is omitted.

[0074]

[0075] Meanwhile, the solid electrolyte according to the present invention may have an average particle size (D50) of 1.0 to 6.0 μm. If the average particle size (D50) of the solid electrolyte is too small, there may be a problem that the ion conductivity is low and it becomes unstable in moisture. If the average particle size (D50) of the solid electrolyte is too large, it may be difficult to form a lithium ion conduction path, and there may be a problem that the ion conductivity deteriorates.

[0076] In this specification, the average particle size (D50) may be defined as the particle size corresponding to 50% of the volume accumulation in the particle size distribution curve. The average particle size (D50) may be measured, for example, using a laser diffraction method.

[0077]

[0078] 2. Method for manufacturing solid electrolyte

[0079] Another embodiment of the present invention provides a method for manufacturing a solid electrolyte comprising the steps of: preparing a sulfide-based lithium ion conductive compound; and forming a coating layer containing fluoride by covering the entire surface of the sulfide-based lithium ion conductive compound in the form of a thin film using an atomic layer deposition (ALD) method with a fluorine precursor and a metal precursor, wherein the metal precursor is aluminum alkoxide or zinc alkoxide.

[0080] Hereinafter, a method for manufacturing a solid electrolyte according to another embodiment of the present invention is described step by step.

[0081]

[0082] First, prepare a sulfide-based lithium ion conductive compound.

[0083] The above sulfide-based lithium ion conductive compound can be prepared by purchasing a commercially available sulfide-based lithium ion conductive compound, or it can be manufactured according to a general manufacturing method for sulfide-based lithium ion conductive compounds in the industry.

[0084] The above sulfide-based lithium ion conductive compound may, more specifically, be an argyrodite-based crystal structure compound.

[0085] The above sulfide-based lithium ion conductive compound can be manufactured by, for example, a step of mixing a lithium raw material, a phosphorus raw material, and a halogen element raw material to form a mixture; and a step of heat-treating the mixture.

[0086] The above lithium raw material may be, for example, Li2S, Li2S2, or a combination thereof, but is not necessarily limited thereto.

[0087] The above-mentioned phosphorus raw material may be, for example, P2S5, P2O5, or a combination thereof, but is not necessarily limited thereto.

[0088] The above-mentioned 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-mentioned halogen element raw material may be LiCl.

[0089] The above mixing can be performed by mechanical mixing or chemical mixing.

[0090] The above mechanical mixing can be performed by methods such as a planetary mill, paint shaker, ball mill, bead mill, homogenizer, hammer mill, turbo mill, disc mill, planetary mill, mechanofusion, etc.

[0091] The above chemical mixing can be performed, for example, by melt quenching.

[0092] The above mixing can be performed for 4 to 12 hours, specifically for 6 to 10 hours, and more specifically for 7 to 9 hours. If the mixing time is too short, the mixing may be insufficient, and the synthesis of the solid electrolyte may not occur well in the heat treatment process described later. If the mixing time is too long, the mixing may be fully completed after a certain period, and even if the mixing is continued further, the mixing state will remain the same, which may cause problems in terms of process efficiency.

[0093] The above mixing can be performed at a rotational speed of 100 to 500 rpm, specifically at 150 to 450 rpm, and more specifically at 200 to 400 rpm. If the rotational speed is too slow, the balls may not penetrate into the powder, resulting in less overall mixing of the powder particles or lower energy, which may lead to insufficient atomization of the powder particles. On the other hand, if the rotational speed is too fast, the powder particles may become concentrated in one area, resulting in less even mixing.

[0094] Of course, if a doping element is to be introduced into a sulfide-based lithium ion conductive compound, additional doping raw materials may be mixed when forming the above mixture.

[0095] Next, optionally as needed, after the step of forming the mixture, the method may further include a step of compressing the mixture to form pellets.

[0096] At this time, the compression can be performed at a pressure of 100 to 500 MPa, specifically 150 to 450 MPa, and more specifically 200 to 400 MPa. If the pressure is too low, a problem may arise where interfacial resistance increases due to insufficient binding between powder particles. On the other hand, if the pressure is too high, the binding between powder particles is already established, so the binding state does not change even if additional pressure is applied, which may cause problems in terms of process efficiency. Therefore, forming pellets at an appropriate pressure is desirable in terms of productivity.

[0097] Next, the above mixture is heat-treated to form a sulfide-based lithium ion conductive compound.

[0098] At this time, the heat treatment can be performed at a temperature of 400 to 700°C, and more specifically at 500 to 600°C. If the heat treatment temperature is too low, the synthesis of the solid electrolyte with an azirodite crystal structure may not occur sufficiently, or it may be synthesized into an amorphous crystal structure, which may result in a decrease in the ionic conductivity of the solid electrolyte. If the heat treatment temperature is too high, the elements constituting the solid electrolyte may vaporize, causing the solid electrolyte to be lost, or impurity phases may be generated, which may result in a decrease in the ionic conductivity of the solid electrolyte.

[0099] In addition, the heat treatment can 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 with an azirodite crystal structure may not occur sufficiently, or it may be synthesized into an amorphous crystal structure, which may result in a decrease in the ionic conductivity of the solid electrolyte. If the heat treatment time is too long, the elements constituting the solid electrolyte may vaporize, causing the solid electrolyte to be lost, or impurity phases may be generated, which may result in a decrease in the ionic conductivity of the solid electrolyte.

[0100] In addition, 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 blocked. The inert gas atmosphere may be, for example, an Ar, N2, H2, or He atmosphere, and more specifically, an Ar atmosphere.

[0101] Next, the sulfide-based lithium ion conductive compound can be ground to control the average particle size (D50), and finally, a final solid electrolyte powder with an average particle size (D50) of 1.0 to 6.0 μm can be obtained.

[0102] At this time, the grinding method is not particularly limited, and, for example, a dry grinding or wet grinding method may be used.

[0103]

[0104] Next, a fluoride-containing coating layer is formed by coating the entire surface of the sulfide-based lithium ion conductive compound in the form of a thin film using an atomic layer deposition (ALD) method with a fluorine precursor and a metal precursor.

[0105] Atomic Layer Deposition (ALD) is a process technology that utilizes Chemical Vapor Deposition (CVD) reactions but suppresses vapor phase reactions by injecting precursors and reactants with a time delay; instead, it employs a self-limited reaction that occurs on the substrate surface to precisely control the thickness of the thin film during deposition. Due to these self-limited reaction characteristics, the ALD process allows for precise control of the thin film thickness to sub-atomic levels, and enables accurate compositional control through thickness control.

[0106] At this time, the metal precursor is aluminum alkoxide or zinc alkoxide and may be in a gaseous state. As the metal precursor is controlled to the said material, the aluminum compound or zinc compound within the coating layer may be formed with a composition containing both fluoride and oxide.

[0107] The amount of metal precursor added can be adjusted so that the content of aluminum or zinc in the final solid electrolyte becomes the aforementioned content.

[0108] In addition, the fluorine precursor may be HF, NH3, NH4F, or a combination thereof, and may be in a gaseous state.

[0109] In addition, the atomic layer deposition can be performed in 2 to 120 cycles, and more specifically in 5 to 70 cycles. If the number of atomic layer deposition cycles is too low, there may be problems such as the coating layer not being formed uniformly, the ratio of oxides and fluorides in the coating layer not being appropriately controlled to a range where moisture stability and ion conductivity can be desirablely achieved simultaneously, or the coating layer thickness being obtained too thin. If the number of atomic layer deposition cycles is too high, there may be problems such as the ratio of oxides and fluorides in the coating layer not being appropriately controlled to a range where moisture stability and ion conductivity can be desirablely achieved simultaneously, or the coating layer thickness being obtained too thick. Therefore, when the number of atomic layer deposition cycles satisfies the above range, the moisture stability of the solid electrolyte can be preferably improved, while preventing significant deterioration of ion conductivity.

[0110] When performing the above atomic layer deposition, one cycle may more specifically involve supplying and reacting a fluorine precursor and a metal precursor on sulfide-based solid electrolyte particles.

[0111] At this time, the fluorine precursor and the metal precursor can be supplied with a time difference according to the atomic layer deposition method, and the metal precursor can be adsorbed first onto the sulfide-based solid electrolyte particles, and then the fluorine precursor can be supplied to induce a reaction with the metal precursor.

[0112] In addition, the atomic layer deposition can be performed at a temperature of 20 to 100°C. If the temperature is too low during atomic layer deposition, there may be a problem with reduced deposition efficiency. If the temperature is too high during atomic layer deposition, there may be a problem with excessive deposition.

[0113] The above atomic layer deposition can be performed at an atmospheric pressure of 2 to 10 torr. If the atmospheric pressure is too low during atomic layer deposition, there may be a problem with excessive deposition. If the atmospheric pressure is too high during atomic layer deposition, there may be a problem with reduced deposition efficiency.

[0114] The above atomic layer deposition can be performed in an argon or nitrogen atmosphere. Accordingly, there may be an advantage in a uniform deposition effect.

[0115]

[0116] 3. All-solid-state battery

[0117] Another embodiment of the present invention provides an all-solid-state battery comprising the aforementioned solid electrolyte.

[0118] More specifically, the above-described all-solid-state battery comprises a positive electrode layer; a negative electrode layer and a solid electrolyte layer located between the positive electrode layer and the negative electrode layer, and at least one of the positive electrode layer, the negative electrode layer and the solid electrolyte layer may comprise the aforementioned solid electrolyte.

[0119] (Bipolar layer)

[0120] More specifically, the anode layer may include an anode current collector and an anode active material layer disposed on the anode current collector.

[0121] 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.

[0122] 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.

[0123] 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 d O2(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 CoGb 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 a compound comprises, for example, a coating element compound of an oxide, hydroxide, oxyhydroxide, oxycarbonate, or hydroxycarbonate of a coating element. The compound forming this 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 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.

[0124] 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.

[0125] 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.

[0126] 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.

[0127] 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.

[0128] 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.

[0129]

[0130] (Cathode layer)

[0131] More specifically, the above cathode layer may include a cathode current collector and a cathode active material layer disposed on the cathode current collector.

[0132] 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.

[0133] 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.

[0134] 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.

[0135] 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.

[0136] 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.

[0137] 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.

[0138] 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.

[0139] 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.

[0140] 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.

[0141] 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.

[0142]

[0143] (Solid electrolyte layer)

[0144] 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.

[0145] 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.

[0146] 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.

[0147] 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.

[0148]

[0149] Another embodiment of the present invention provides an electric vehicle comprising the all-solid-state battery.

[0150]

[0151] 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.

[0152]

[0153] Example 1

[0154] (1) Preparation of solid electrolyte

[0155] (Preparation of sulfide-based lithium ion conductive compound) The raw materials Li2S, P2S5, and LiCl were mixed at 300 rpm for about 8 hours using a planetary mill by adjusting the stoichiometric ratio so that the final solid electrolyte composition was Li6PS5Cl to form a mixture.

[0156] Afterwards, a pressure of 300 MPa was applied to the above mixture to form pellets.

[0157]

[0158] Subsequently, the above pellets were heat-treated at 550°C for 8 hours in an argon (Ar) atmosphere to produce an argyrodite-based compound with a composition of Li6PS5Cl.

[0159] After (coating), the solid electrolyte was introduced into the reaction chamber of an Atomic Layer Deposition (ALD) apparatus. At this time, the reaction chamber was controlled to an Ar or N2 atmosphere, a temperature of 20 to 100°C, and a pressure of 2 to 10 torr. Subsequently, NH3, NH4F, or HF as a fluorine precursor and aluminum alkoxide as a metal precursor were introduced onto the surface of the solid electrolyte in the reaction chamber and deposited using the ALD method. At this time, the number of ALD cycles performed was set to 3 cycles.

[0160] Thus, a solid electrolyte was prepared in which an aluminum compound-containing coating layer was formed on the surface of a azirodite-based compound particles.

[0161] (2) Manufacturing of solid-state batteries

[0162] The solid electrolyte prepared above is used as the electrolyte layer, and Li1Ni is used as the positive electrode active material. 0.8 Co 0.1 Mn 0.1 An all-solid-state battery was manufactured using O2 and an In-Li alloy as the negative electrode active material.

[0163]

[0164] Example 2

[0165] A solid electrolyte and an all-solid-state battery were manufactured in the same manner as in Example 1, except that the number of atomic layer deposition cycles was 10.

[0166]

[0167] Example 3

[0168] A solid electrolyte and an all-solid-state battery were manufactured in the same manner as in Example 1, except that the number of atomic layer deposition cycles was 50.

[0169]

[0170] Example 4

[0171] A solid electrolyte and an all-solid-state battery were manufactured in the same manner as in Example 1, except that the number of atomic layer deposition cycles was 80.

[0172]

[0173] Example 5

[0174] A solid electrolyte and an all-solid-state battery were manufactured in the same manner as in Example 1, except that the number of atomic layer deposition cycles was 100.

[0175]

[0176] Example 6

[0177] A solid electrolyte was prepared by carrying out the same procedure as in Example 1, except that zinc alkoxide was used as a metal precursor in the coating step, thereby forming a zinc compound-containing coating layer on the surface of an azirodite-based compound particle.

[0178]

[0179] Example 7

[0180] A solid electrolyte and an all-solid-state battery were prepared by carrying out the same procedure as in Example 6, except that the number of atomic layer deposition cycles was 10.

[0181]

[0182] Example 8

[0183] A solid electrolyte and an all-solid-state battery were prepared in the same manner as in Example 6, except that the number of atomic layer deposition cycles was 50.

[0184]

[0185] Example 9

[0186] A solid electrolyte and an all-solid-state battery were prepared in the same manner as in Example 6, except that the number of atomic layer deposition cycles was 80.

[0187]

[0188] Example 10

[0189] A solid electrolyte and an all-solid-state battery were prepared in the same manner as in Example 6, except that the number of atomic layer deposition cycles was 100.

[0190]

[0191] Comparative Example 1

[0192] A solid electrolyte and an all-solid-state battery were prepared by carrying out the same procedure as in Example 1, except that the coating step was not performed.

[0193]

[0194] Table 1 below summarizes the process conditions of Examples 1 to 10 and Comparative Example 1.

[0195] Comparison of Metal Precursor ALD Cycle Count Example 1 -- Example 1 Aluminum Alkoxide 3 Example 2 Aluminum Alkoxide 10 Example 3 Aluminum Alkoxide 50 Example 4 Aluminum Alkoxide 80 Example 5 Aluminum Alkoxide 100 Example 6 Zinc Alkoxide 3 Example 7 Zinc Alkoxide 10 Example 8 Zinc Alkoxide 50 Example 9 Zinc Alkoxide 80 Example 10 Zinc Alkoxide 100

[0196] Tables 2 and 3 below summarize the results of the evaluation of the solid electrolyte properties and all-solid-state battery electrochemical characteristics described below.

[0197] Presence of 1st Peak Presence of 2nd Peak Second Peak / 1st Peak Peak Intensity Non-coating Layer Main Compound Composition Average Coating Layer Thickness (nm) Al Metal Element Content (Wt%) Zn Metal Element Content (Wt%) Ionic Conductivity (Before Atmosphere Exposure) (mS / cm) Moisture Stability (%) Comparative Example 1 XX ----- 2.374 Example 1 OO 0.01 AlF3+Al2O 3 0.01 0.001 -1.975 Example 2 OO 0.15 AlF3+Al2O 3 0.05 0.01 -1.680 Example 3 OO 0.18 AlF3+Al2O 3 0.1 0.02 -1.385 Example 4 OO 0.26 AlF3+Al2O 3 0.3 0.1 -0.986 Example 6: ZnF2+ZnO 0.01 -0.002 0.587 Example 7: ZnF2+ZnO 0.06 -0.03 1.179 Example 8: ZnF2+ZnO 0.14 -0.06 0.684 Example 9: ZnF2+ZnO 0.4 -0.31 0.584 Example 10: ZnF2+ZnO 0.7 -0.56 0.285

[0198] Initial Discharge Capacity (mAh / g) Initial Efficiency (%) Comparison Example 1 20388.1 Example 1 20388.9 Example 2 21089.5 Example 3 20990.2 Example 4 20890 Example 5 20891.3 Example 6 20289.9 Example 7 21090.4 Example 8 20989.8 Example 9 20889.8 Example 10 20589.6

[0199] Experimental Example 1: Evaluation of Solid Electrolyte Properties

[0200] (1) XPS analysis

[0201] The composition of the main compound within the coating layer was confirmed through main peak analysis by performing X-ray Photoelectron Spectroscopy (XPS) analysis on the outermost surface of the solid electrolyte.

[0202] In particular, for Examples 1 to 5 (aluminum coating), the occurrence of a first peak appearing in the region where the binding energy is 73 to 74 eV and a second peak appearing in the region where the binding energy is 75 to 76 eV, and the peak intensity ratio between them (second peak / first peak) were further analyzed.

[0203] In this regard, Figure 1 is a graph of the XPS analysis results of the solid electrolyte prepared according to Example 2.

[0204] (2) Evaluation of average thickness of coating layer

[0205] First, the coating layer thickness for a single solid electrolyte particle was determined by observing the solid electrolyte particle using a TEM (transmission electron microscope) image and calculating the average value of the thickness for 10 measurement regions along the entire perimeter of the solid electrolyte particle. Next, the average thickness of the coating layer was determined by calculating the average value of the coating layer thickness obtained using the same method as above for 20 randomly selected solid electrolyte particles among the solid electrolyte powders.

[0206] (3) Evaluation of metal element (Al or Zn) content

[0207] The content of metal elements (Al or Zn) based on the total weight of the solid electrolyte was evaluated by considering the weight of the finally produced solid electrolyte and the amount of metal precursor added during the atomic layer deposition coating process.

[0208] (4) Ionic conductivity and moisture stability evaluation

[0209] 1) Evaluation of ion conductivity (before atmospheric exposure) (25℃, 0.1C)

[0210] 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.

[0211] 2) Evaluation of ion conductivity after atmospheric exposure (25℃, 0.1C)

[0212] In a dry room with a dew point of about -45℃, 0.5g of a solid electrolyte in powder form was left for about 8 hours, then recovered, and the impedance was remeasured using the same method as above.

[0213] 3) Moisture stability evaluation

[0214] Moisture stability was derived by converting the ion conductivity after atmospheric exposure to the ion conductivity before atmospheric exposure into a percentage (%).

[0215]

[0216] Experimental Example 2: Evaluation of Electrochemical Characteristics of All-Solid State Battery

[0217] (1) Evaluation of initial discharge capacity and initial efficiency

[0218] The charging was performed at room temperature (25℃) at 0.1C to 4.25V (vs. Li+ / Li), and the application of the charging current was terminated by setting the current amount to 0.02C at that voltage. After discharging to 2.50V (vs. Li+ / Li) at 0.1C under the same conditions, the initial discharge capacity and initial efficiency were evaluated.

[0219]

[0220] Referring to Tables 1 to 3, it was confirmed that in Examples 1 to 10, in which an ALD coating process was performed using aluminum alkoxide or zinc alkoxide as a metal precursor, moisture stability was improved compared to Comparative Example 1, in which no coating process was performed. In addition, as indicated by the analysis results of the main compound of the coating layer, it was confirmed that the compound in the coating layer according to the present invention has a composition containing both aluminum or zinc fluorides and oxides.

[0221] Furthermore, it was observed that as the number of ALD cycles increased, the average thickness of the coating layer increased (or the content of Al and Zn metal elements increased), which enhanced the effect of moisture stability, but degraded ionic conductivity. Therefore, it was found that appropriate control of the number of ALD cycles is an important factor for simultaneously achieving desirable moisture stability and ionic conductivity.

[0222] Looking more closely at Examples 1 to 5 in which aluminum coating was performed, it was confirmed that in the case of Examples 2 and 3, where the peak intensity ratio of the second peak to the first peak, the average thickness of the coating layer, or the Al metal element content were more appropriately controlled, moisture stability was improved while excessive deterioration of ion conductivity was prevented.

[0223] Looking more closely at Examples 6 to 10 in which zinc coating was performed, it was confirmed that in the case of Examples 7 and 8, where the average thickness of the coating layer or the content of the Zn metal element was more appropriately controlled, moisture stability was improved while excessive deterioration of ion conductivity was prevented.

[0224]

[0225] 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.

[0226] Therefore, the substantive scope of the present invention shall be defined by the appended claims and their equivalents.

Claims

1. A sulfide-based lithium ion conductive compound; and a coating layer containing an aluminum compound that covers the entire surface of the sulfide-based lithium ion conductive compound in the form of a thin film, and A solid electrolyte in which, during X-ray Photoelectron Spectroscopy (XPS) analysis, a first peak appears in the region where the binding energy is 73 to 74 eV and a second peak appears in the region where the binding energy is 75 to 76 eV.

2. In Paragraph 1, A solid electrolyte in which the first peak is a peak derived from aluminum fluoride and the second peak is a peak derived from aluminum oxide.

3. In Paragraph 1, A solid electrolyte in which the peak intensity ratio of the second peak to the first peak (second peak / first peak) is 0.005 to 0.

8.

4. In Paragraph 1, The above aluminum compound is a solid electrolyte containing AlF3 and Al2O3.

5. In Paragraph 1, The coating layer is a solid electrolyte having an average thickness of 0.008 to 0.8 nm.

6. In Paragraph 1, A solid electrolyte in which the aluminum content in the solid electrolyte is 0.0008 to 0.3 weight% based on the total weight of the solid electrolyte.

7. In Paragraph 1, The above sulfide-based lithium ion conductive compound is a solid electrolyte having an argyrodite-based crystal structure.

8. In Paragraph 1, A solid electrolyte having an average particle size (D50) of 1.0 to 6.0 μm.

9. A solid electrolyte comprising a sulfide-based lithium ion conductive compound; and a coating layer containing zinc fluoride that covers the entire surface of the sulfide-based lithium ion conductive compound in the form of a thin film.

10. In Paragraph 9, The above zinc fluoride is a solid electrolyte containing ZnF2.

11. In Paragraph 9, The above coating layer is a solid electrolyte further containing zinc oxide.

12. In Paragraph 9, The above coating layer is a solid electrolyte having an average thickness of 0.005 to 1 nm.

13. In Paragraph 9, A solid electrolyte in which the zinc content in the solid electrolyte is 0.001 to 1 weight% based on the total weight of the solid electrolyte.

14. In Paragraph 9, The above sulfide-based lithium ion conductive compound is a solid electrolyte having an argyrodite-based crystal structure.

15. In Paragraph 9, A solid electrolyte having an average particle size (D50) of 1.0 to 6.0 μm.

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