Sulfide-based solid electrolyte, method for producing same, and all-solid-state battery comprising same

Abstract

The present invention relates to a sulfide-based solid electrolyte, a method for producing same, and an all-solid-state battery comprising same. More specifically, the present invention includes forming Li2S and using the Li2S to form Li7-aPS6-aXa (0≤a≤2), wherein forming the Li2S includes: mixing lithium sulfate (Li2SO4) and a carbon reducing agent to form a mixture; and heat-treating the mixture, and the X includes at least one of F, Cl, Br, and I.

Description

Sulfide-based solid electrolyte, method for producing the same, and all-solid-state battery comprising the same

[0001] The present invention relates to a sulfide-based solid electrolyte, a method for producing the same, and an all-solid-state battery including the same.

[0002] Recent industrial demands have led to the active development of batteries with high energy density and safety. For example, lithium-ion batteries are being used not only in information and communication devices, but also in the automotive sector. Safety is particularly important in the automotive sector, as it is directly related to life.

[0003] Recently, all-solid-state batteries, which replace the electrolyte with a solid electrolyte, have been proposed. By eliminating the use of flammable organic dispersion media, all-solid-state batteries significantly reduce the risk of fire or explosion in the event of a short circuit. Therefore, these all-solid-state batteries can significantly improve safety compared to lithium-ion batteries that use electrolytes.

[0004] The problem to be solved by the present invention is to provide a method for manufacturing a sulfide-based solid electrolyte having high purity and high ionic conductivity.

[0005] Another problem to be solved by the present invention is to provide a sulfide-based solid electrolyte having high purity and high ionic conductivity.

[0006] Another problem to be solved by the present invention is to provide an all-solid-state battery having excellent electrochemical performance.

[0007] A method for manufacturing a sulfide-based solid electrolyte according to one embodiment of the present invention comprises: forming Li2S; and using the Li2S to manufacture Li 7-a PS 6-a X a(0≤a≤2), wherein forming Li2S comprises: mixing lithium sulfate (Li2SO4) and a carbon reductant to form a mixture; and heat-treating the mixture, wherein X may include at least one of F, Cl, Br, and I.

[0008] A sulfide-based solid electrolyte according to one embodiment of the present invention can be manufactured using the manufacturing method described above.

[0009] An all-solid-state battery according to one embodiment of the present invention may include the above-described sulfide-based solid electrolyte.

[0010] A method for manufacturing a sulfide-based solid electrolyte according to one embodiment of the present invention can produce a sulfide-based solid electrolyte having high purity and high ionic conductivity. Furthermore, the sulfide-based solid electrolyte can be manufactured economically and mass-produced.

[0011] A sulfide-based solid electrolyte according to one embodiment of the present invention can have excellent purity and ionic conductivity.

[0012] An all-solid-state battery according to one embodiment of the present invention can have excellent electrochemical performance.

[0013] Figure 1 is a cross-sectional view of an all-solid-state battery according to one embodiment of the present invention.

[0014] Figure 2 is a cross-sectional view of an all-solid-state battery according to another embodiment of the present invention.

[0015] Figure 3 is a cross-sectional view of an all-solid-state battery according to another embodiment of the present invention.

[0016] Figure 4 is a flow chart for explaining a method for manufacturing a sulfide-based solid electrolyte according to embodiments of the present invention.

[0017] FIG. 5 is an X-ray photoelectron spectroscopy (XPS) spectrum before and after the first heat treatment during the production of a sulfur precursor (Li2S) according to an embodiment.

[0018] Figure 6 is an X-ray diffraction (XRD) spectrum for a sulfur precursor (Li2S) according to an embodiment.

[0019] FIG. 7 is a scanning electron microscope (SEM) and energy dispersive spectroscopy (EDS) mapping image of a sulfur precursor (Li2S) according to an embodiment.

[0020] Figure 8 is a comparison result of Raman spectra when only a sulfur precursor (Li2S) was added to an acetonitrile solvent during the manufacturing of an example, and when a sulfur precursor (Li2S) and a phosphorus precursor (P2S5) were added to an acetonitrile solvent.

[0021] Figure 9 is a scanning electron microscope (SEM) image of the embodiment.

[0022] Figure 10 is an X-ray diffraction (XRD) spectrum for Examples 1 and 2.

[0023] Figure 11 shows the results of electrochemical impedance spectroscopy (EIS) of Examples 1 and 2.

[0024] To fully understand the structure and effects of the present invention, preferred embodiments of the present invention will be described with reference to the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but can be implemented in various forms and subject to various modifications. However, the description of these embodiments is provided solely to ensure a complete disclosure of the present invention and to fully inform those skilled in the art of the invention of the scope of the invention.

[0025] In this specification, when a component is referred to as being on another component, it means that it can be formed directly on the other component, or a third component may be interposed between them. Furthermore, in the drawings, the thicknesses of the components are exaggerated for the sake of clarity. Parts designated by the same reference numerals throughout the specification represent the same components.

[0026] Embodiments described herein will be described with reference to cross-sectional and / or plan views, which are ideal illustrations of the present invention. In the drawings, the thicknesses of films and regions are exaggerated for the purpose of effectively explaining the technical contents. Accordingly, the regions illustrated in the drawings have a schematic nature, and the shapes of the regions illustrated in the drawings are intended to illustrate specific shapes of regions of the device and are not intended to limit the scope of the invention. Although terms such as first, second, and third are used to describe various components in various embodiments of the present specification, these components should not be limited by such terms. These terms are used only to distinguish one component from another. The embodiments described and illustrated herein also include complementary embodiments thereof.

[0027] The terminology used herein is for the purpose of describing embodiments and is not intended to limit the present invention. In this specification, the singular also includes the plural unless specifically stated otherwise. As used herein, the words "comprises" and / or "comprising" do not exclude the presence or addition of one or more other components.

[0028] As used herein, “combination thereof” may mean mixtures, laminates, composites, copolymers, alloys, blends, and reaction products of the components.

[0029] Unless otherwise defined herein, the particle size may be the average particle size. In addition, the particle size refers to the average particle size (D50), which means the diameter of particles with a cumulative volume of 50% by volume in a particle size distribution. The average particle size (D50) can be measured by a method well known to those skilled in the art, for example, by measuring with a particle size analyzer, or by measuring with a transmission electron microscope (TEM) photograph or a scanning electron microscope (SEM) photograph. Alternatively, the average particle size (D50) value can be obtained by measuring with a measuring device that utilizes dynamic light-scattering, performing data analysis to count the number of particles for each particle size range, and calculating from the counted number. Alternatively, the average particle size (D50) value can be obtained by measuring with a laser diffraction method. When measuring by laser diffraction, more specifically, after the particles to be measured are dispersed in a dispersion medium, they are introduced into a commercially available laser diffraction particle size measuring device (e.g., Microtrac MT 3000) and irradiated with ultrasonic waves of approximately 28 kHz at an output of 60 W, and the average particle size (D50) based on 50% of the particle size distribution in the measuring device can be calculated.

[0030] In this specification, each of the phrases "A or B", "at least one of A and B", "at least one of A or B", "A, B, or C", "at least one of A, B, and C", and "at least one of A, B, or C" may include any one of the items listed together in that phrase, or all possible combinations thereof.

[0031]

[0032] Figure 1 is a cross-sectional view of an all-solid-state battery (10) according to one embodiment of the present invention.

[0033] Referring to FIG. 1, an all-solid-state battery (10) according to one embodiment includes a positive electrode layer (100), a negative electrode layer (200) facing the positive electrode layer (100), and a solid electrolyte layer (300) disposed between the positive electrode layer (100) and the negative electrode layer (200). However, the present invention is not limited thereto, and the all-solid-state battery (10) may further include an additional functional layer, such as an adhesion enhancing layer, disposed between the positive electrode layer (100) and the solid electrolyte layer (300) or between the negative electrode layer (200) and the solid electrolyte layer (300).

[0034] The positive electrode layer (100) of one embodiment includes a positive electrode current collector (110) and a positive electrode active material layer (120) disposed on the positive electrode current collector (110). The positive electrode active material layer (120) may include a positive electrode active material, a solid electrolyte, a conductive material, and a binder.

[0035] The cathode current collector (110) can provide a reference surface on which the cathode active material layer (120) is arranged. The cathode current collector (110) can include a plate or foil including, 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 an alloy thereof.

[0036] Meanwhile, unlike that illustrated in FIG. 1, in one embodiment of the present invention, the positive electrode current collector (110) may be omitted. Although not illustrated, a carbon layer having a thickness of 0.1 μm to 4 μm may be additionally disposed between the positive electrode current collector (110) and the positive electrode active material layer (120) to increase the bonding strength between the positive electrode current collector (110) and the positive electrode active material layer (120).

[0037] A cathode active material is a material that can reversibly absorb and desorb lithium ions. The cathode active material may include, but is not necessarily limited to, lithium transition metal oxides such as lithium cobalt oxide (LCO), lithium nickel oxide, lithium nickel cobalt oxide, lithium nickel cobalt aluminum oxide (NCA), lithium nickel cobalt manganese oxide (NCM), lithium manganate, and lithium iron phosphate, nickel sulfide, copper sulfide, lithium sulfide, iron oxide, or vanadium oxide. The cathode active materials may be used alone or as a mixture of two or more.

[0038] Lithium transition metal oxides include, for example, Li a A 1-b B b D2(0.90≤a≤1, 0≤b≤0.5), Li a E 1-b B b O 2-c D c (0.90≤a≤1, 0≤b≤0.5, 0≤c≤0.05), LiE 2-b B b O 4-c D c (0≤b≤0.5, 0≤c≤0.05), Li a Ni 1-b-c Co b B c D α (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 (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(0.90≤a≤1, 0≤b≤0.5, 0≤c≤0.05, 0<α≤2), Li a Nor 1-b-c Mn b B c O 2-α F α (0.90≤a≤1, 0≤b≤0.5, 0≤c≤0.05, 0<α<2), Li a Nor b E c G d O2(0.90≤a≤1, 0≤b≤0.9, 0≤c≤0.5, 0.001≤d≤0.1), Li a Nor b Co c Mn d GeO2(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(0.9≤a≤1, 0.001≤b≤0.1), Li a CoG b O2(0.90≤a≤1, 0.001≤b≤0.1), Li a MnG b O2(0.90≤a≤1, 0.001≤b≤0.1), Li a Mn2GbO4(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-fA compound represented by any one of Fe2(PO4)3(0≤f≤2), LiFePO4. In these compounds, the capital letter “A” is Ni, Co, Mn, or a combination thereof, the capital letter “B” is Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, a rare earth element, or a combination thereof, the capital letter “D” is O, F, S, P, or a combination thereof, the capital letter “E” is Co, Mn, or a combination thereof, the capital letter “F” is F, S, P, or a combination thereof, the capital letter “G” is Al, Cr, Mn, Fe, Mg, La, Ce, Sr, V, or a combination thereof, the capital letter “Q” is Ti, Mo, Mn, or a combination thereof, the capital letter “I” is Cr, V, Fe, Sc, Y, or a combination thereof, and the capital letter “J” is V, Cr, Mn, Co, Ni, Cu, or a combination thereof.

[0039] The cathode active material may include, for example, a lithium salt of a transition metal oxide having a layered rock salt type structure among the lithium transition metal oxides described above. The "layered rock salt type structure" is, for example, a cubic rock salt type structure. <111> It is a structure in which oxygen atomic layers and metal atomic layers are alternately and regularly arranged in a direction, and thereby each atomic layer forms a two-dimensional plane. The "cubic rock salt structure" refers to the sodium chloride type (NaCl type) structure, which is a type of crystal structure, and specifically refers to a structure in which the face-centered cubic lattice (fcc) formed by each cation and anion is arranged with a displacement of half of the ridge of the unit lattice. Lithium transition metal oxides having this layered rock salt structure include, for example, LiNi x Co y Al z O2(NCA) or LiNi x Co y Mn zO2(NCM) (0 <x<1,0<y<1, 0<z<1, x+y+z=1) 등의 삼원계 리튬전이금속산화물일 수 있다. 양극활물질이 층상암염형 구조를 갖는 삼원계 리튬전이금속산화물을 포함하는 경우, 전고체 전지(10)의 에너지 밀도가 커지고 열안정성이 향상될 수 있다.

[0040] The above-described compound included in the positive electrode active material may be covered by a coating layer (not shown). The positive electrode active material may also be a mixture of the above-described compound and a compound to which a coating layer is added. Meanwhile, the coating layer added to the surface of the positive electrode active material may include, for example, an oxide, a hydroxide, an oxyhydroxide, an oxycarbonate, or a hydroxycarbonate of the coating elements below. The compound forming the coating layer may be amorphous or crystalline. The coating elements included in the coating layer may include Mg, Al, Co, K, Na, Ca, Si, Ti, V, Sn, Ge, Ga, B, As, Zr, or mixtures thereof. The coating layer may include, for example, Li2O-ZrO2 (LZO). The method of forming the coating layer is selected within a range that does not adversely affect the physical properties of the positive electrode active material. The method of forming the coating layer includes, for example, spray coating, dipping, etc.

[0041] When the cathode active material contains nickel (Ni) as a ternary lithium transition metal oxide such as NCA or NCM, for example, the capacity density of the all-solid-state battery (10) can be increased, thereby reducing metal dissolution of the cathode active material in a charged state. As a result, the cycle characteristics of the all-solid-state battery (10) in a charged state are improved. Meanwhile, the “cycle characteristics” are characteristics indicating the degree to which the all-solid-state battery (10) is deteriorated due to charge / discharge of the all-solid-state battery (10). An all-solid-state battery (10) with high cycle characteristics may have a small degree of deterioration of the all-solid-state battery (10) due to charge / discharge, and an all-solid-state battery (10) with low cycle characteristics may have a large degree of deterioration of the all-solid-state battery (10) due to charge / discharge.

[0042] The shape of the cathode active material may include particle shapes such as a sphere or an ellipsoid, for example. The particle size and content of the cathode active material are not particularly limited.

[0043] The solid electrolyte may include a sulfide-based solid electrolyte having excellent lithium ion conductivity characteristics. Examples of the sulfide-based solid electrolyte include Li2S-P2S5, Li2S-P2S5-LiX (X is a halogen element), Li2S-P2S5-Li2O, Li2S-P2S5-Li2O-LiI, Li2S-SiS2, Li2S-SiS2-LiI, Li2S-SiS2-LiBr, Li2S-SiS2-LiCl, Li2S-SiS2-B2S3-LiI, Li2S-SiS2-P2S5-LiI, Li2S-B2S3, Li2S-P2S5-Z. m S n (m, n are positive numbers, capital letter “Z” represents Ge, Zn or Ga), Li2S-GeS2, Li2S-SiS2-Li3PO4, Li2S-SiS2-Li p MO q (p, q are positive numbers, capital letter “M” is one of P, Si, Ge, B, Al, Ga In), Li 7-x PS 6-x Cl x (0≤x≤2), Li 7-x PS 6-x Br x (0≤x≤2), and Li 7-x PS 6-x I x It may include at least one selected from (0≤x≤2).

[0044] Sulfide-based solid electrolytes include, for example, Li 7-x PS 6-x Cl x (0≤x≤2), Li 7-x PS 6-x Br x (0≤x≤2), and Li 7-x PS 6-x I xIt may be an argyrodite-type compound including at least one selected from (0≤x≤2). In particular, the sulfide-based solid electrolyte may be an argyrodite-type compound including at least one selected from Li6PS5Cl, Li6PS5Br, and Li6PS5I.

[0045] Alternatively, the sulfide-based solid electrolyte is Li 7-a M a PS 6-c X c It may be an argyrodite-type compound containing (0≤a≤2, 0≤c≤2), where X may be F, Br, Cl, or a combination thereof. M can be candium (Sc), yttrium (Y), titanium (Ti), zirconium (Zr), hafnium (Hf), vanadium (V), niobium (Nb), tantalum (Ta), chromium (Cr), molybdenum (Mo), tungsten (W), manganese (Mn), technetium (Tc), rhenium (Re), iron (Fe), ruthenium (Ru), osmium (Os), cobalt (Co), rhodium (Rh), iridium (Ir), nickel (Ni), palladium (Pd), platinum (Pt), copper (Cu), silver (Ag), gold (Au), zinc (Zn), cadmium (Cd), mercury (Hg), aluminum (Al), gallium (Ga), indium (In), thallium (Tl), silicon (Si), germanium (Ge), tin (Sn), lead (Pb), arsenic (As), antimony (Sb), bismuth (Bi), or a combination thereof.

[0046] The density of the argyrodite-type solid electrolyte may be 1.5 g / cc to 2.0 g / cc. Since the argyrodite-type solid electrolyte has a density of 1.5 g / cc or more, the internal resistance of the all-solid-state battery is reduced, and the defect of the solid electrolyte membrane being penetrated and short-circuited due to the formation of lithium dendrites can be prevented. The elastic modulus of the solid electrolyte may be, for example, 15 GPa to 35 GPa.

[0047] The solid electrolyte included in the positive electrode active material layer (120) may have a smaller median particle size (D50) than the solid electrolyte included in the solid electrolyte layer (300). For example, the median particle size (D50) of the solid electrolyte included in the positive electrode active material layer (120) may be 90% or less, 80% or less, 70% or less, 60% or less, 50% or less, 40% or less, 30% or less, or 20% or less of the median particle size (D50) of the solid electrolyte included in the solid electrolyte layer (300). Meanwhile, the median particle size (D50) may be a median diameter measured using a laser particle size distribution meter.

[0048] The cathode active material layer (120) may include a conductive material. The conductive material may have conductivity without causing chemical changes in the all-solid-state battery (10), thereby increasing the conductivity of the cathode active material and the solid electrolyte. The conductive material may include a carbon-based material. The conductive material may include, for example, one or more selected from graphite, carbon black, acetylene black, carbon nanofibers, and carbon nanotubes.

[0049] The positive electrode active material layer (120) may further include a binder. The binder may include a material for binding the positive electrode active material, solid electrolyte, and conductive material included in the positive electrode active material layer (120) and improving bonding strength with the positive electrode current collector (110). The binder may include, for example, polyvinylidene fluoride, styrene butadiene rubber (SBR), polytetrafluoroethylene, polyvinylidene fluoride, vinylidene fluoride / hexafluoropropylene copolymer, polyacrylonitrile, and polymethyl methacrylate.

[0050] Based on 100 parts by weight of the total of the positive electrode active material, the solid electrolyte, the conductive material, and the binder, the positive electrode active material layer (120) may include 60 parts by weight or more and 92 parts by weight or less of the positive electrode active material. Based on 100 parts by weight of the total of the positive electrode active material, the solid electrolyte, the conductive material, and the binder, the positive electrode active material layer (120) may include 0 parts by weight or more and 1.5 parts by weight or less of the binder.

[0051] Based on 100 parts by weight of the solid electrolyte, the positive electrode active material layer (120) may include 1 part by weight or more and 50 parts by weight or less of a conductive material. If the conductive material is included in the positive electrode active material layer (120) in an amount of less than 1 part by weight based on 100 parts by weight of the solid electrolyte, the proportion of the conductive material may decrease, thereby lowering the electrical conductivity of the positive electrode active material layer (120). If the conductive material is included in the positive electrode active material layer (120) in an amount of more than 50 parts by weight based on 100 parts by weight of the solid electrolyte, the proportion of the conductive material may be excessively high, so that a covering layer covering the surface of the solid electrolyte may not be properly formed.

[0052] The cathode active material layer (120) may further include additives such as fillers, coating agents, dispersants, and ion conductive aids in addition to the cathode active material, solid electrolyte, conductive agent, and binder described above.

[0053] The solid electrolyte layer (300) is disposed between the positive electrode layer (100) and the negative electrode layer (200) and includes a sulfide-based solid electrolyte having excellent lithium ion conductivity characteristics. The solid electrolyte included in the solid electrolyte layer (300) may be the same as or different from any one of the materials that may be included in the solid electrolyte included in the positive electrode active material layer (120) described above.

[0054] The solid electrolyte layer (300) of one embodiment may include a sulfide-based solid electrolyte. The sulfide-based solid electrolyte may be manufactured by treating starting materials such as Li2S and P2S5 by a melting rapid cooling method or a mechanical milling method. In addition, a heat treatment may be performed after the treatment. The solid electrolyte may be amorphous, crystalline, or a mixture thereof. In addition, the solid electrolyte may include, for example, at least sulfur (S), phosphorus (P), and lithium (Li) as constituent elements among the above-described sulfide-based solid electrolyte materials. For example, the solid electrolyte may be a material including Li2S-P2S5. When using a sulfide-based solid electrolyte material including Li2S-P2S5 to form the solid electrolyte, the mixing molar ratio of Li2S and P2S5 is, for example, in the range of Li2S:P2S5=50:50 to 90:10.

[0055] Sulfide-based solid electrolytes include, for example, Li 7-x PS 6-x Cl x (0≤x≤2), Li 7-x PS 6-x Br x (0≤x≤2), and Li 7-x PS 6-x I x It may be an argyrodite-type compound including at least one selected from (0≤x≤2). In particular, the sulfide-based solid electrolyte may be an argyrodite-type compound including at least one selected from Li6PS5Cl, Li6PS5Br, and Li6PS5I.

[0056] Alternatively, the sulfide-based solid electrolyte is Li 7-a M a PS 6-c X cIt may be an argyrodite-type compound containing (0≤a≤2, 0≤c≤2), where X may be F, Br, Cl, or a combination thereof. M can be candium (Sc), yttrium (Y), titanium (Ti), zirconium (Zr), hafnium (Hf), vanadium (V), niobium (Nb), tantalum (Ta), chromium (Cr), molybdenum (Mo), tungsten (W), manganese (Mn), technetium (Tc), rhenium (Re), iron (Fe), ruthenium (Ru), osmium (Os), cobalt (Co), rhodium (Rh), iridium (Ir), nickel (Ni), palladium (Pd), platinum (Pt), copper (Cu), silver (Ag), gold (Au), zinc (Zn), cadmium (Cd), mercury (Hg), aluminum (Al), gallium (Ga), indium (In), thallium (Tl), silicon (Si), germanium (Ge), tin (Sn), lead (Pb), arsenic (As), antimony (Sb), bismuth (Bi), or a combination thereof.

[0057] The density of the argyrodite-type solid electrolyte may be 1.5 g / cc to 2.0 g / cc. When the argyrodite-type solid electrolyte has a density of 1.5 g / cc or more, the internal resistance of the all-solid-state battery is reduced, and the defect of the solid electrolyte membrane being penetrated and short-circuited due to the formation of lithium dendrites can be prevented. The elastic modulus of the solid electrolyte is, for example, 15 GPa to 35 GPa.

[0058] The solid electrolyte layer (300) may further include a binder. The binder included in the solid electrolyte layer (300) may be, for example, styrene butadiene rubber (SBR), polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, etc., but is not limited thereto. The binder of the solid electrolyte layer (300) may be the same as or different from the binder included in the positive electrode active material layer (120) or the binder included in the coating layer (220).

[0059] For example, unlike the one shown, the solid electrolyte layer (300) may include a plurality of solid electrolyte layers.

[0060] The negative electrode layer (200) may include a negative electrode current collector (210) and a coating layer (220) on the negative electrode current collector (210). The negative electrode current collector (210) may provide a reference surface on which the coating layer (220) is disposed. The negative electrode current collector (210) may include, for example, a material that does not react with lithium, i.e., does not form an alloy or a compound with lithium. For example, the negative electrode current collector (210) may include at least one metal selected from the group consisting of copper (Cu), stainless steel, titanium (Ti), iron (Fe), cobalt (Co), and nickel (Ni). The thickness of the negative electrode current collector (210) may be about 10 μm. The thickness of the negative electrode current collector (210) may be 1 μm to 20 μm, more specifically 5 μm to 15 μm, and more specifically 7 μm to 10 μm.

[0061] The negative electrode current collector (210) may be composed of one of the above-described metals, or may include an alloy or coating material of two or more metals. The negative electrode current collector (210) may have, for example, a plate shape or a foil shape. Meanwhile, in one embodiment, the negative electrode current collector (210) may be omitted.

[0062] The cathode layer (200) may further include a second electrode tab extending from one side of the cathode current collector (210). The second electrode tab may be welded to an electrode lead and connected to an external terminal. The electrode lead welded to the second electrode tab may be different from the electrode lead welded to the first electrode tab.

[0063] The coating layer (220) can allow lithium metal to grow between the all-solid-state battery (10) and the negative electrode current collector (210) when the all-solid-state battery (10) is charged. Alternatively, the coating layer (220) can form an alloy with lithium or allow lithium metal to grow inside the all-solid-state battery (10) when the all-solid-state battery (10) is charged. The coating layer (220) can serve as a protective layer for the lithium metal and simultaneously suppress the precipitation and growth of lithium dendrites.

[0064] The coating layer (220) may include a metal and carbon. For example, the coating layer (220) may include at least one metal selected from the group consisting of gold (Au), platinum (Pt), palladium (Pd), silicon (Si), silver (Ag), aluminum (Al), bismuth (Bi), tin (Sn), and zinc (Zn). The coating layer (220) may include at least one carbon selected from the group consisting of carbon black, acetylene black, furnace black, ketjen black, and graphene. In one embodiment, the coating layer (220) may include a mixture of carbon black and silver (Ag).

[0065] The coating layer (220) may further include additives other than metal and carbon. For example, the coating layer (220) may further include at least one additive selected from the group consisting of a binder, a filler, a coating agent, a dispersant, and an ion conductive additive.

[0066] The coating layer (220) may have a smaller thickness than the positive electrode active material layer (120). The thickness of the coating layer (220) may be, for example, 50% or less, 40% or less, 30% or less, 20% or less, 10% or less, or 5% or less of the thickness of the positive electrode active material layer (120). The thickness of the coating layer (220) may be, for example, 1 μm to 20 μm, 2 μm to 10 μm, or 3 μm to 7 μm. The thickness of the coating layer (220) may be about 10 μm. If the thickness of the coating layer (220) is too thin, lithium dendrites formed between the coating layer (220) and the negative electrode current collector (210) may collapse the coating layer (220), thereby deteriorating the cycle characteristics of the all-solid-state battery (10). If the thickness of the coating layer (220) increases excessively, the energy density of the all-solid-state battery (10) may decrease and the internal resistance of the all-solid-state battery (10) due to the coating layer (220) may increase, thereby deteriorating the cycle characteristics of the all-solid-state battery (10).

[0067] Meanwhile, although not shown, a carbon layer may be further included to improve adhesion between the coating layer (220) and the solid electrolyte layer (300).

[0068] For example, unlike the one illustrated, the areas of the cathode layer (200) and the anode layer (100) may be different. Specifically, the area of ​​the cathode layer (200) may be larger than the area of ​​the anode layer (100). The anode layer (100) may be completely overlapped within the cathode layer (200).

[0069] For example, the solid electrolyte layer (300) may have substantially the same area as the cathode layer (200).

[0070] Specifically, the anode layer (100) may have a first width (WI1) in the first direction (D1). The cathode layer (200) may have a second width (WI2) in the first direction (D1). The first width (WI1) may be smaller than the second width (WI2).

[0071] The difference between the second width (W2) and the first width (W1) may be 10 mm or less. Specifically, the difference between the second width (W2) and the first width (W1) may be 8 mm or less, 5 mm or less, or 3 mm or less. The difference between the second width (W2) and the first width (W1) may be 0.1 mm or more, 0.5 mm or more, or 1 mm or more. If the above numerical range is exceeded, the size of the positive electrode layer (100) becomes relatively small, so the discharge capacity may be lowered, and the energy density of the all-solid-state battery (10) may be reduced. If the above numerical range is not reached, it may be difficult to suppress the formation of lithium dendrites in the negative electrode, which may cause a short circuit.

[0072] For example, although not shown, the all-solid-state battery (10) may further include a gasket to fill the step on the side of the all-solid-state battery (10) caused by the difference in area between the positive electrode layer (100) and the negative electrode layer (200).

[0073] Figures 2 and 3 are cross-sectional views of an all-solid-state battery (10) according to other embodiments of the present invention. In the embodiments described below, detailed descriptions of technical features that overlap with those described above with reference to Figure 1 will be omitted, and differences will be described in detail.

[0074] Referring to FIG. 2, the negative electrode layer (200) of the all-solid-state battery (10) may further include a lithium metal layer (400) between the negative electrode collector (210) and the coating layer (220). The lithium metal layer (400) may be formed or its thickness may further increase when the all-solid-state battery (10) is charged. The coating layer (220) serves as a protective layer for the lithium metal layer (400), and at the same time, may suppress the growth of lithium dendrites from the lithium metal layer (400).

[0075] The lithium metal layer (400) may be a metal thin film containing lithium or a lithium alloy. The lithium alloy may include, but is not limited to, a Li-Al alloy, a Li-Sn alloy, a Li-In alloy, a Li-Ag alloy, a Li-Au alloy, a Li-Zn alloy, a Li-Ge alloy, a Li-Si alloy, etc., and any lithium alloy may be used. The lithium metal layer (400) may contain one of these alloys or lithium. Alternatively, the lithium metal layer (400) may contain various types of alloys.

[0076] The lithium metal layer (400) may have a third width (WI3) in the first direction (D1). The third width (WI3) may be equal to or greater than the first width (WI1). The third width (WI3) may be equal to or less than the second width (WI2). For example, the third width (WI3) may be greater than the first width (WI1) and less than the second width (WI2).

[0077] Referring to FIG. 3, the negative electrode layer (200) of the all-solid-state battery (10) includes a negative electrode current collector (210) and a negative electrode active material layer (230) disposed on the negative electrode current collector (210). The negative electrode active material layer (230) may include a negative electrode active material and a binder.

[0078] The negative electrode active material included in the negative electrode active material layer (230) may have a particle form. The median particle size average particle diameter (D50) of the negative electrode active material having a particle form may be, for example, 4 μm or less, 2 μm or less, 1 μm or less, or 900 nm or less. The median particle size average particle diameter (D50) of the negative electrode active material may be, for example, 10 nm to 4 μm, 10 nm to 2 μm, or 10 nm to 900 nm. When the negative electrode active material has a median particle size average diameter (D50) in this range, reversible absorption and / or desorption of lithium may be facilitated during charge and discharge. Meanwhile, the median particle size average diameter (D50) may be a median diameter measured using a laser particle size distribution meter.

[0079] The negative electrode active material may include, for example, at least one selected from a carbon-based negative electrode active material and a metal or metalloid negative electrode active material.

[0080] The carbon-based negative electrode active material may be amorphous carbon, in particular. Examples of amorphous carbon include, but are not limited to, carbon black (CB), acetylene black (AB), furnace black (FB), ketjen black (KB), and graphene. Amorphous carbon is carbon that has no crystallinity or very low crystallinity, and is distinguished from crystalline carbon or graphitic carbon.

[0081] The metal or metalloid negative electrode active material includes, but is not limited to, one or more selected from the group consisting of gold (Au), platinum (Pt), palladium (Pd), silicon (Si), silver (Ag), aluminum (Al), bismuth (Bi), tin (Sn), and zinc (Zn), and may be a metal negative electrode active material or a metalloid negative electrode active material that forms an alloy or compound with lithium. On the other hand, nickel (Ni) does not form an alloy with lithium and therefore is not a metal negative electrode active material.

[0082] The negative electrode active material layer (230) includes one type of negative electrode active material among these negative electrode active materials, or includes a mixture of multiple different negative electrode active materials. For example, the negative electrode active material layer (230) may include only amorphous carbon, or may include one or more selected from the group consisting of gold (Au), platinum (Pt), palladium (Pd), silicon (Si), silver (Ag), aluminum (Al), bismuth (Bi), tin (Sn), and zinc (Zn).

[0083] In one embodiment, the negative electrode active material layer (230) may include a mixture of amorphous carbon and one or more selected from the group consisting of gold (Au), platinum (Pt), palladium (Pd), silicon (Si), silver (Ag), aluminum (Al), bismuth (Bi), tin (Sn), and zinc (Zn). The mixing ratio of the mixture of amorphous carbon and gold (Au), etc., may be, for example, 10:1 to 1:2, 5:1 to 1:1, or 4:1 to 2:1 by weight, but is not necessarily limited to this range and may be selected according to the required characteristics of the all-solid-state battery (10). When the negative electrode active material has this composition, the cycle characteristics of the all-solid-state battery (10) may be further improved.

[0084] The binder included in the negative electrode active material layer (230) may be, for example, styrene butadiene rubber (SBR), polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, vinylidene fluoride / hexafluoropropylene copolymer, polyacrylonitrile, polymethyl methacrylate, etc., but is not necessarily limited thereto. The binder may include a single binder or a plurality of different binders.

[0085] Since the negative electrode active material layer (230) includes a binder, the negative electrode active material layer (230) can be stably formed on the negative electrode current collector (210). That is, the bonding strength between the negative electrode active material layer (230) and the negative electrode current collector (210) can be increased. In addition, cracking of the negative electrode active material layer (230) is suppressed despite changes in the volume and / or relative positions of the negative electrode active material layer (230) during the charge and discharge process. If the negative electrode active material layer (230) does not include a binder, the negative electrode active material layer (230) can be easily separated from the negative electrode current collector (210). As the negative electrode active material layer (230) is detached from the negative electrode current collector (210), the negative electrode current collector (210) can come into contact with the solid electrolyte layer at the exposed portion, thereby increasing the possibility of a short circuit occurring.

[0086] The negative electrode active material layer (230) is manufactured, for example, by providing a mixture in which the materials constituting the negative electrode active material layer (230) are dispersed onto the negative electrode current collector (210). Since a binder is included in the materials constituting the negative electrode active material layer (230), stable dispersion of the negative electrode active material in the mixture is possible. For example, when applying the mixture onto the negative electrode current collector (210) by screen printing, it is possible to suppress clogging of the screen (e.g., clogging by aggregates of the negative electrode active material) by the binder.

[0087] The negative electrode active material layer (230) may further include other additives in addition to the negative electrode active material and binder. The negative electrode active material layer (230) may further include, for example, fillers, coating agents, dispersants, ion conductive additives, etc.

[0088] The negative electrode active material layer (230) may have a smaller thickness than the positive electrode active material layer (120). The thickness of the negative electrode active material layer (230) may be, for example, 50% or less, 40% or less, 30% or less, 20% or less, 10% or less, or 5% or less of the thickness of the positive electrode active material layer (120). The thickness of the negative electrode active material layer (230) may be, for example, 1 um to 20 um, 2 um to 10 um, or 3 um to 7 um. If the thickness of the negative electrode active material layer (230) is too thin, lithium dendrites formed between the negative electrode active material layer (230) and the negative electrode current collector (210) may collapse the negative electrode active material layer (230), thereby deteriorating the cycle characteristics of the all-solid-state battery (10). If the thickness of the negative electrode active material layer (230) increases excessively, the energy density of the all-solid-state battery (10) may decrease and the internal resistance of the all-solid-state battery (10) due to the negative electrode active material layer (230) may increase, thereby deteriorating the cycle characteristics of the all-solid-state battery (10).

[0089] If the thickness of the negative electrode active material layer (230) decreases, the charge capacity of the negative electrode active material layer (230) may also decrease, for example. The charge capacity of the negative electrode active material layer (230) is, for example, 50% or less, 40% or less, 30% or less, 20% or less, 10% or less, 5% or less, or 2% or less than the charge capacity of the positive electrode active material layer (120). The charge capacity of the negative electrode active material layer (230) is, for example, 0.1% to 50%, 0.1% to 40%, 0.1% to 30%, 0.1% to 20%, 0.1% to 10%, 0.1% to 5%, or 0.1% to 2% than the charge capacity of the positive electrode active material layer (120). If the charge capacity of the negative electrode active material layer (230) is excessively small, the thickness of the negative electrode active material layer (230) becomes very thin, and the same defects as the defects described above that occur when the thickness of the negative electrode active material layer (230) becomes excessively thin may occur. If the charge capacity of the negative electrode active material layer (230) increases excessively, the same defects as the defects described above that occur when the thickness of the negative electrode active material layer (230) increases excessively may occur.

[0090] The charge capacity of the positive electrode active material layer (120) can be obtained by multiplying the charge capacity density (mAh / g) of the positive electrode active material by the mass of the positive electrode active material of the positive electrode active material layer (120). When the positive electrode active material layer (120) includes several types of positive electrode active materials, the [charge capacity density Х mass] value is calculated for each positive electrode active material, and the sum of these values ​​of the positive electrode active materials is the charge capacity of the positive electrode active material layer (120). The charge capacity of the negative electrode active material layer (230) can also be calculated in the same way. That is, the charge capacity of the negative electrode active material layer (230) is obtained by multiplying the charge capacity density (mAh / g) of the negative electrode active material by the mass of the negative electrode active material in the negative electrode active material layer (230). When the negative electrode active material layer (230) includes several types of negative electrode active materials, the [charge capacity density Х mass] value is calculated for each negative electrode active material, and the sum of these values ​​of the negative electrode active materials is the capacity of the negative electrode active material layer (230). Here, the charge capacity density of the positive electrode active material and the negative electrode active material may be an estimated capacity using an all-solid-state half-cell using lithium metal as a counter electrode. The charge capacity of the positive electrode active material layer (120) and the negative electrode active material layer (230) can be directly measured by measuring the charge capacity using the all-solid-state half-cell. The charge capacity density can be obtained by dividing the measured charge capacity by the mass of each active material. Meanwhile, in the present specification, the “charge capacity” of the positive electrode active material layer (120) and the negative electrode active material layer (230) means the initial charge capacity measured at the time of the first cycle charge.

[0091] Meanwhile, although not shown, a carbon layer may be further included to improve adhesion between the negative electrode active material layer (230) and the solid electrolyte layer (300).

[0092]

[0093] Hereinafter, a sulfide-based solid electrolyte and a method for manufacturing the same according to embodiments of the present invention will be described in more detail. For convenience of explanation, the same details as those described with reference to FIGS. 1 to 3 will be omitted, and differences will be described in detail.

[0094]

[0095] Method for manufacturing sulfide-based solid electrolyte

[0096] Figure 4 is a flow chart for explaining a method for manufacturing a sulfide-based solid electrolyte according to embodiments of the present invention.

[0097] Referring to FIG. 4, the method for manufacturing a sulfide-based solid electrolyte according to the present invention comprises: forming Li2S (S100); and using Li2S to form Li 7-a PS 6-a X a (0≤x≤2) may include forming (S300). X may include at least one of F, Cl, Br, and I.

[0098]

[0099] Li2S may be a sulfur precursor. Forming Li2S (S100) may include forming a mixture by mixing lithium sulfate (Li2SO4) and a carbon reductant (S120); and heat treating the mixture (S140).

[0100] Lithium sulfate (Li2SO4) is a raw material for making sulfur precursors and may be a cheaper raw material than sulfur precursors (Li2S).

[0101] A carbon reductant may be a substance capable of carbothermic reduction. Carbon reductants can undergo reduction reactions at high temperatures. Carbothermic reduction can result in the formation of at least one of carbon monoxide and carbon dioxide. Carbon reductants can reduce lithium sulfate (Li2SO4).

[0102] For example, the carbon reductant may include at least one of glucose, sucrose, lactic acid, citric acid, methanol, formaldehyde, or a combination thereof.

[0103] Lithium sulfate (Li2SO4) and a carbon reductant can be mixed in a weight ratio of 1:0.33 to 1:10. For example, the weight ratio of lithium sulfate (Li2SO4) and a carbon reductant can be 1:0.5 to 1:5, or 1:1 to 1:3. When the weight ratio of lithium sulfate (Li2SO4) and a carbon reductant satisfies the above-described range, the carbon reductant can sufficiently reduce lithium sulfate (Li2SO4) in the heat treatment step, and form Li2S.

[0104] The mixing of lithium sulfate (Li2SO4) and a carbon reductant can be performed using a dry process. Through the mixing process, lithium sulfate (Li2SO4) and a carbon reductant can be sufficiently mixed, and the lithium sulfate (Li2SO4) and a carbon reductant can be uniformly mixed.

[0105] Heat treatment of the first mixture (S140) may include a first heat treatment and a second heat treatment.

[0106] The first heat treatment can be performed at a temperature of 200°C to 600°C. For example, the first heat treatment can be performed at a temperature of 200°C to 400°C.

[0107] The first heat treatment can be performed for 1 to 5 hours. For example, the first heat treatment can be performed for 2 to 4 hours.

[0108] The first heat treatment can be performed in an air atmosphere. The inert atmosphere may be composed of nitrogen, argon, or other gases, but is not necessarily limited to these. Any inert atmosphere used in the relevant technical field may be used.

[0109] Through the first heat treatment, the carbon reductant can be chemically changed to increase its reactivity with lithium sulfate (Li2SO4). For example, through the first heat treatment, the C-O bond in the carbon reductant can be oxidized to a C=O bond. Through the first heat treatment, the initial reaction between lithium sulfate (Li2SO4) and the carbon reductant can be promoted. The carbon reductant can initiate the reduction reaction of lithium sulfate (Li2SO4). Through the first heat treatment, partial reduction of lithium sulfate (Li2SO4) can occur, and some Li2S can be formed. At this time, at least one of carbon monoxide or carbon dioxide can be formed. Through the first heat treatment, unnecessary impurities can be removed or substances that do not participate in the reaction can be allowed to escape in a gaseous form. Through the first heat treatment, heat can be evenly transferred to lithium sulfate (Li2SO4) and a carbon reductant, and the reaction between lithium sulfate (Li2SO4) and the carbon reductant can be gradually induced. The first heat treatment can create an environment in which lithium sulfate (Li2SO4) and the carbon reductant can effectively react in the second heat treatment process.

[0110] The temperature of the second heat treatment may be higher than the temperature of the first heat treatment. The second heat treatment may be performed at a temperature of 700°C to 1000°C. For example, the second heat treatment may be performed at a temperature of 800°C to 1000°C.

[0111] The second heat treatment may be performed for 2 to 8 hours. For example, the second heat treatment may be performed for 4 to 6 hours.

[0112] The second heat treatment can be performed under an inert atmosphere. The inert atmosphere may be composed of nitrogen, argon, or other gases, but is not necessarily limited to these. Any inert atmosphere used in the relevant technical field may be used.

[0113] Through the second heat treatment, lithium sulfate (Li2SO4) and a carbon reductant can sufficiently react. The carbon reductant can sufficiently reduce lithium sulfate (Li2SO4). Through the second heat treatment, the reduction reaction of lithium sulfate (Li2SO4) can be completed. Through the second heat treatment, unnecessary impurities can be sufficiently removed or substances that do not participate in the reaction can sufficiently escape in gaseous form. Through the second heat treatment, Li2S can be formed. For example, the formed carbon monoxide or carbon dioxide can be released, so that Li2S with small pores and high density can be formed.

[0114] Through the first and second heat treatments, high purity Li2S can be formed.

[0115] In one embodiment of the present invention, forming Li2S (S100) may further include performing soaking, filtering, and drying on the heat treatment product (S160).

[0116] For example, the heat-treated product may further contain an unreacted carbon reducing agent in addition to Li2S. For example, the heat-treated product may further contain impurities containing sulfur (S) or carbon (C) in addition to Li2S. Through this step, Li2S with a higher purity can be formed.

[0117] Through soaking and filtration, unreacted carbon reducing agent can be removed. Through soaking and filtration, impurities containing sulfur (S) or carbon (C) can be removed.

[0118] Immersion can be performed by immersing the heat-treated product in a water-soluble solvent. The water-soluble solvent can selectively dissolve Li2S. The water-soluble solvent may not dissolve unreacted carbon reducing agents, sulfur (S), or carbon (C)-containing impurities, etc. For example, the water-soluble solvent can be water, ethanol, acetone, methanol, etc.

[0119] The immersion can be performed at a temperature of 20°C to 60°C. For example, the immersion can be performed at 20°C to 40°C. When the immersion is performed within the temperature range described above, Li2S can be selectively dissolved. In another example, to more quickly dissolve Li2S, the immersion can be performed at 40°C to 60°C.

[0120] The soaking can be performed for 1 to 3 hours. If the soaking is performed for the time described above, Li2S can be selectively dissolved.

[0121] For example, in order to completely remove unreacted carbon reducing agent, impurities containing sulfur (S) or carbon (C), etc., and obtain Li2S with higher purity, the soaking may be performed twice or more.

[0122] Through filtration, a solution containing dissolved Li2S can be obtained.

[0123] The filtered solution can be dried. Drying can produce Li2S with high purity. For example, drying can include primary drying and secondary drying.

[0124] For example, primary drying can be performed using a stirrer. Primary drying can be performed at a rotation speed of 300 rpm to 800 rpm, or 400 rpm to 600 rpm. Primary drying can be performed at a temperature of 50°C to 150°C, or 100°C to 150°C. Primary drying can be performed for 4 to 12 hours, or 4 to 6 hours.

[0125] For example, secondary drying can be performed under vacuum. Secondary drying can be performed at a temperature of 50°C to 150°C, or 100°C to 150°C. Secondary drying can be performed for 8 to 16 hours, or 10 to 14 hours.

[0126] By using the method for producing Li2S according to the present invention, Li2S with high purity can be produced. The purity of Li2S according to the present invention can be 98% or higher. For example, the purity of Li2S can be 98% to 99.99%, 98% to 99.98%, or 98% to 99%. Li2S can be substantially free of impurities. For example, the purity of Li2S can be measured by X-ray diffraction (XRD), inductively coupled plasma spectrometry (ICP), thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FT-IR), etc. By using Li2S with high purity, a sulfide-based solid electrolyte with excellent purity and ionic conductivity can be produced.

[0127] The XRD spectrum of Li2S can show clear and strong diffraction peaks. The peaks appearing in the XRD spectrum of Li2S can be symmetrical. The XRD spectrum of Li2S can show narrow and strong peaks. The XRD spectrum of Li2S has a low background signal, and the peaks can be clearly distinguished from the background.

[0128] For example, in an XRD spectrum using CuKα rays, the Li2S of the present invention may include a first peak corresponding to the (111) plane, a second peak corresponding to the (200) plane, a third peak corresponding to the (220) plane, a fourth peak corresponding to the (311) plane, and a fifth peak corresponding to the (222) plane. The maximum intensity of the first peak corresponding to the (111) plane may appear at a diffraction angle (2θ) in the range of 25° to 30°. The maximum intensity of the second peak corresponding to the (200) plane may appear at a diffraction angle (2θ) in the range of 30° to 35°. The maximum intensity of the third peak corresponding to the (220) plane may appear at a diffraction angle (2θ) in the range of 42° to 48°. The maximum intensity of the fourth peak corresponding to the (311) plane may appear at a diffraction angle (2θ) in the range of 50° to 54°. The maximum intensity of the fifth peak corresponding to the (222) plane can appear at a diffraction angle (2θ) in the range of 55° to 60°.

[0129] For example, the XRD measurement may be performed under conditions of a diffraction angle (2θ) of 10° to 90°, a scan speed of 0.01° / s to 1° / s, and a step size of 0.013° / step to 0.039° / step.

[0130] The full width at half maximum (FWHM) of the first peak, the second peak, the third peak, the fourth peak, and the fifth peak may be 0.05° to 0.3°. When the full width at half maximum (FWHM) satisfies the range described above, Li2S may have excellent purity.

[0131] Li using Li2S 7-a PS6-a X a Forming (S300) of (0≤x≤2) may include preparing a precursor solution by mixing a sulfur precursor Li2S, a phosphorus precursor, a halide precursor, and a non-oxygenated solvent (S320); and drying and performing a third heat treatment on the precursor solution (S340).

[0132] For example, Li2S may be the heat treatment product described above. As another example, Li2S may be the product obtained by soaking, filtering, and drying the heat treatment product described above.

[0133] For example, the phosphorus precursor may include at least one of phosphorus pentasulfide (P2S5), red phosphorus, white phosphorus, diphosphorus pentoxide (P2O5), diammonium phosphate ((NH4)2HPO4), ammonium dihydrogen phosphate ((NH4)H2PO4), disodium phosphate (Na2HPO4), trisodium phosphate (Na3PO4), or a combination thereof.

[0134] For example, the halide precursor may be a lithium halide. For example, the lithium halide may include at least one of LiF, LiCl, LiBr, LiI, or a combination thereof.

[0135] The sulfur precursor Li2S, the phosphorus precursor, and the halide precursor can be individually weighed and mixed so that the sulfide-based solid electrolyte has the desired composition.

[0136] Li 7-a PS 6-a X a The formation of (0≤x≤2) (S300) can be performed by a wet process using a solvent. By using a wet process, the dispersibility of the precursors can be increased compared to when the precursors are mixed by a dry process, the precursors can be mixed uniformly, and the chemical reaction between the precursors can be performed evenly.

[0137] The solvent may be a non-oxygenated solvent. A non-oxygenated solvent may be a solvent that does not contain oxygen (O). A non-oxygenated solvent may be a solvent that is not chemically bonded to oxygen (O) or a solvent that is not a compound containing oxygen (O). For example, the non-oxygenated solvent may include at least one of acetonitrile, an alkane, benzene, toluene, xylene, dichloromethane, or a combination thereof. By using a non-oxygenated solvent, side reactions between precursors such as phosphorus precursors and the solvent can be prevented, and the purity of the sulfide-based solid electrolyte can be increased.

[0138] The content of the non-oxygen solvent was controlled so that the solid content in the precursor solution was 10 wt% to 70 wt%. The solid content may include a sulfur precursor, a phosphorus precursor, and a halide precursor. In other words, the content of the non-oxygen solvent may be 30 wt% to 90 wt% based on the total weight of the precursor solution. When the content of the non-oxygen solvent satisfies the above-described range, the dispersibility of the precursors can be increased, the precursors can be uniformly mixed, and the chemical reaction between the precursors can be uniformly performed. In addition, an argyrodite-type sulfide-based solid electrolyte having the desired chemical formula can be manufactured.

[0139] Mixing of a sulfur precursor, Li2S, a phosphorus precursor, a halide precursor, and a non-oxygenated solvent can be performed with relatively little energy. For example, the mixing can be performed using a stirrer. For example, the stirrer can include a magnetic stirrer, a mechanical stirrer, etc.

[0140] Mixing can be performed at a temperature of 20°C to 80°C. For example, mixing can be performed at a temperature of 20°C to 30°C.

[0141] Mixing can be performed at a rotation speed of 100 rpm to 900 rpm. For example, mixing can be performed at a rotation speed of 300 rpm to 800 rpm, or 400 rpm to 600 rpm.

[0142] Mixing can be performed for 4 to 10 hours. For example, mixing can be performed for 5 to 7 hours.

[0143] Mixing can be performed in an environment free of moisture and oxygen. For example, mixing can be performed under an inert atmosphere. The inert atmosphere may be composed of, but is not limited to, nitrogen, argon, or other gases. Any inert atmosphere used in the relevant technical field can be used.

[0144] The precursor solution may be dried. Through drying, a precursor powder may be obtained. For example, the drying may include primary drying and secondary drying.

[0145] For example, primary drying can be performed using a stirrer. Primary drying can be performed at a rotation speed of 300 rpm to 800 rpm, or 400 rpm to 600 rpm. Primary drying can be performed at a temperature of 50°C to 150°C, or 100°C to 150°C. Primary drying can be performed for 4 to 12 hours, or 5 to 7 hours.

[0146] For example, secondary drying can be performed under vacuum. Secondary drying can be performed at a temperature of 100°C to 200°C, or 150°C to 200°C. Secondary drying can be performed for 8 to 16 hours, or 10 to 14 hours.

[0147] When the temperature and time are within the above-described ranges, the solvent can be sufficiently removed. In addition, an amorphous precursor powder is formed, allowing for easy control of the particle size of the sulfide-based solid electrolyte, and a sulfide-based solid electrolyte with high purity and high ionic conductivity can be produced.

[0148] A third heat treatment can be performed on the precursor powder. The third heat treatment can be performed at a temperature of 300°C to 600°C. For example, the third heat treatment can be performed at a temperature of 300°C to 550°C, or 350°C to 550°C.

[0149] The third heat treatment can be performed for 1 hour to 40 hours. The third heat treatment can be performed for 1 hour to 30 hours, 1 hour to 20 hours, or 2 hours to 10 hours.

[0150] The third heat treatment can be performed under an inert atmosphere. The inert atmosphere may be composed of nitrogen, argon, or other gases, but is not necessarily limited to these. Any inert atmosphere used in the relevant technical field may be used.

[0151] If the temperature, time, and atmosphere of the third heat treatment satisfy the above-described ranges, an argyrodite-type sulfide-based solid electrolyte can be easily obtained. Furthermore, a sulfide-based solid electrolyte with high purity and high ionic conductivity can be obtained.

[0152] For example, Li 7-a PS 6-a X a Forming (S300) (0≤a≤2) may include forming a radical containing sulfur; and dissolving a precursor with the radical.

[0153] A sulfur precursor and a non-oxygen solvent can react to form a radical containing sulfur. For example, the radical is S3 ㆍ- It could be.

[0154] Radicals can be highly reactive. Radicals can increase the solubility of phosphorus precursors. For example, a dissolved phosphorus precursor can be PS4. 3- It could be (Li3PS4).

[0155] The dissolved phosphorus precursor can react with the halide precursor. This allows the production of an argyrodite-type sulfide-based solid electrolyte having the desired chemical formula. Furthermore, a sulfide-based solid electrolyte with excellent purity and ionic conductivity can be produced.

[0156] Unlike the one shown, for example, Li according to the present invention 7-a PS 6-a X a Forming (S300) (0≤a≤2) may further include a crushing or sieving process so that the sulfide-based solid electrolyte has a desired particle size.

[0157]

[0158] Using the Li2S manufacturing method of the present invention, Li2S, a high-purity sulfur precursor, can be manufactured. Furthermore, since the sulfur precursor is manufactured using inexpensive lithium sulfate (Li2SO4) and a carbon reducing agent, Li2S can be manufactured economically, and the cost of manufacturing a sulfide-based solid electrolyte can be reduced.

[0159] By using the method for manufacturing a sulfide-based solid electrolyte according to the present invention, Li2S, which is a sulfur precursor, can be directly manufactured, and by using this, a sulfide-based solid electrolyte can be manufactured at once (one-pot synthesis). In addition, a sulfide-based solid electrolyte can be manufactured with less energy, the cost of manufacturing a sulfide-based solid electrolyte can be reduced, and mass production is possible. By using the method for manufacturing a sulfide-based solid electrolyte of the present invention, a sulfide-based solid electrolyte with high purity and high ionic conductivity can be manufactured.

[0160]

[0161] Sulfide-based solid electrolyte

[0162] The sulfide-based solid electrolyte according to embodiments of the present invention can be manufactured by the above-described manufacturing method.

[0163] The sulfide-based solid electrolyte according to the present invention may be included in an all-solid-state battery (10). The sulfide-based solid electrolyte may be included in at least one of the solid electrolyte layer (300), the positive electrode layer (100), and the negative electrode layer (200). For example, the sulfide-based solid electrolyte may be included in the solid electrolyte layer (300). For example, the sulfide-based solid electrolyte may be included in the positive electrode active material layer (120). For example, the sulfide-based solid electrolyte may be included in the coating layer (220).

[0164] Sulfide-based solid electrolyte is Li 7-a PS 6-a X a It may be an argyrodite-type compound having a chemical formula of (0≤a≤2). X may include at least one of F, Cl, Br, and I. In particular, the sulfide-based solid electrolyte may be an argyrodite-type compound including at least one selected from Li6PS5F, Li6PS5Cl, Li6PS5Br, and Li6PS5I.

[0165] The particle size of the sulfide-based solid electrolyte may be 0.1 μm to 100 μm. For example, the particle size of the sulfide-based solid electrolyte may be 0.1 μm to 50 μm, 0.1 μm to 10 μm, or 0.5 μm to 5 μm.

[0166] The purity of the sulfide-based solid electrolyte may be 98% or higher. For example, the purity of the sulfide-based solid electrolyte may be 98% to 99.99%, 98% to 99.98%, or 98% to 99%. The sulfide-based solid electrolyte may be substantially free of impurities. For example, the purity of the sulfide-based solid electrolyte may be measured by X-ray diffraction (XRD), inductively coupled plasma spectrometry (ICP), thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FT-IR), or the like. When the purity of the sulfide-based solid electrolyte satisfies the above-described range, the sulfide-based solid electrolyte may have excellent ionic conductivity.

[0167] The XRD spectrum of sulfide-based solid electrolytes may exhibit distinct and strong diffraction peaks. The peaks appearing in the XRD spectrum of sulfide-based solid electrolytes may be symmetrical. The XRD spectrum of sulfide-based solid electrolytes may exhibit narrow and strong peaks. The XRD spectrum of sulfide-based solid electrolytes has a low background signal, and the peaks can be clearly distinguished from the background.

[0168] For example, in an XRD spectrum using CuKα rays, the sulfide-based solid electrolyte of the present invention may include a sixth peak corresponding to the (111) plane, a seventh peak corresponding to the (200) plane, an eighth peak corresponding to the (220) plane, a ninth peak corresponding to the (311) plane, and a tenth peak corresponding to the (222) plane. The maximum intensity of the sixth peak corresponding to the (111) plane may appear at a diffraction angle (2θ) in the range of 12° to 16°. The maximum intensity of the seventh peak corresponding to the (200) plane may appear at a diffraction angle (2θ) in the range of 17° to 20°. The maximum intensity of the eighth peak corresponding to the (220) plane may appear at a diffraction angle (2θ) in the range of 22° to 27°. The maximum intensity of the ninth peak corresponding to the (311) plane may appear at a diffraction angle (2θ) in the range of 28° to 31°. The maximum intensity of the 10th peak corresponding to the (222) plane can appear at a diffraction angle (2θ) in the range of 32° to 35°.

[0169] For example, the XRD measurement may be performed under conditions of a diffraction angle (2θ) of 10° to 90°, a scan speed of 0.01° / s to 1° / s, and a step size of 0.013° / step to 0.039° / step.

[0170] The full width at half maximum (FWHM) of the sixth peak, seventh peak, eighth peak, ninth peak, and tenth peak may be 0.05° to 0.3°. When the full width at half maximum (FWHM) satisfies the above-described range, the sulfide-based solid electrolyte may have excellent purity.

[0171] The ionic conductivity of the sulfide-based solid electrolyte at 25°C may be 2 mS / cm or more. For example, the ionic conductivity of the sulfide-based solid electrolyte at 25°C may be 2 mS / cm to 20 mS / cm, or 2 mS / cm to 10 mS / cm.

[0172] An all-solid-state battery including a sulfide-based solid electrolyte according to the present invention can have excellent electrochemical performance.

[0173]

[0174] Hereinafter, the present invention will be described in more detail through examples. However, these examples are intended to exemplify the present invention and the scope of the present invention is not limited to these examples.

[0175]

[0176] Example

[0177] Li2SO4 and glucose were mixed in a weight ratio of 1:2. The mixture was pre-sintered at 300°C for 3 hours in an air atmosphere, and then sintered at 900°C for 5 hours in an Ar atmosphere to obtain Li2S. The prepared Li2S, P2S5, and LiCl were each weighed to obtain the desired composition of Li6PS5Cl, added to an acetonitrile (ACN) solvent, and mixed at 500 rpm for 6 hours using a magnetic stirrer at 25°C to prepare a precursor solution. The mixing was performed in an environment free of moisture and oxygen. The content of the acetonitrile (ACN) solvent was controlled so that the content of solids (Li2S, P2S5, and LiCl) in the precursor solution was 20 wt%. The precursor solution was dried at 500 rpm for 6 hours using a magnetic stirrer at 130°C, and then dried at 180°C for 12 hours under vacuum to obtain a precursor powder. The precursor powder was subjected to a third heat treatment at 550°C for 5 hours under an Ar atmosphere to produce a sulfide-based solid electrolyte (Li6PS5Cl).

[0178]

[0179] Comparative Example 1

[0180] Li2S (Sigma-Aldrich, purity 99.98%) was prepared. Li2S and P2S5 were weighed in equivalent amounts to obtain a sulfide-based solid electrolyte (Li6PS5Cl), and then added to THF to prepare a first mixture. Here, the content of THF was controlled so that the solid content in the first mixture was 10 wt%.

[0181] Separately, Li2S and LiCl were weighed in equivalent amounts to obtain a sulfide-based solid electrolyte (Li6PS5Cl) and dissolved in ethanol (Sigma-Aldrich) to prepare a second mixture. The ethanol content was controlled so that the solid content in the second mixture was 15 wt%.

[0182] The first and second mixtures were mixed and stirred at 25°C using a magnetic stirrer for 6 hours. The resulting mixture was dried under vacuum at 140°C for 12 hours. The dried resultant was heat-treated in a furnace under an Ar atmosphere at 550°C for 5 hours to produce a sulfide-based solid electrolyte (Li6PS5Cl).

[0183]

[0184] Comparative Example 2

[0185] Li6PS5Cl (POSCO JK Solid Solution, purity 98-99%) with an argyrodite structure was prepared. This was manufactured by weighing Li2S, P2S5, and LiCl to obtain the target composition of Li6PS5Cl, then performing mechanical milling in a dry process using high-energy mill equipment, followed by heat treatment.

[0186]

[0187] Experimental Example 1: Preparation and Property Analysis of Li2S

[0188] The results of the physical property analysis for Li2S manufactured in the examples are shown in FIGS. 5 to 7.

[0189] Figure 5 shows the manufacturing process of Li2S according to the embodiment, before the first heat treatment (Before 1 st HTR) and after the first heat treatment (After 1 st This is the XPS spectrum of HTR). Referring to Fig. 5, when manufacturing Li2S according to the example, peaks that were not visible before the first heat treatment appeared after the first heat treatment. In particular, in the XPS spectrum after the first heat treatment, a C=O peak was observed. This confirmed that the CO bond in glucose was oxidized to a C=O bond, reacted with Li2SO4, generated CO2, and ultimately produced Li2S.

[0190] Fig. 6 is an XRD spectrum measured using CuKα rays for Li2S according to an embodiment. XRD measurements were performed under the conditions of a diffraction angle (2θ) of 0° to 90°, a scan speed of 0.0167° / s, and a step size of 0.02° / step. Referring to Fig. 6, in the XRD spectrum for Li2S according to an embodiment, a peak appeared at the same diffraction angle as ref Li2S (Sigma-Aldrich, purity 99.98%), and no peak was observed at other diffraction angles. The XRD spectrum for Li2S according to the embodiment included a first peak corresponding to the (111) plane at a diffraction angle (2θ) of 28°, a second peak corresponding to the (200) plane at a diffraction angle (2θ) of 32°, a third peak corresponding to the (220) plane at a diffraction angle (2θ) of 45°, a fourth peak corresponding to the (311) plane at a diffraction angle (2θ) of 53°, and a fifth peak corresponding to the (222) plane at a diffraction angle (2θ) of 55°. The full widths at half maximum (FWHM) of the first, second, third, fourth, and fifth peaks were each 0.05° to 0.3°, and the difference between them and the full widths at half maximum of the peaks of ref Li2S was 1% or less. Thus, it was confirmed that Li2S having a high purity of 98% or more and not including impurities can be manufactured using the manufacturing method according to the embodiment.

[0191] Fig. 7 shows SEM and EDS mapping images of Li2S according to an embodiment. SEM and EDS mapping were performed by loading Li2S according to an embodiment onto carbon tape. Referring to Fig. 7, it was confirmed that the particles of Li2S according to an embodiment did not contain carbon (C). Accordingly, it was confirmed that Li2S having a high purity of 98% or higher and containing no impurities can be manufactured using the manufacturing method according to an embodiment.

[0192] Li2S according to the example could be manufactured at a cost of 2% of that of commercialized Li2S (Daejung Chemical Gold Co., Ltd., purity 98-99%). In other words, it was confirmed that Li2S with high purity could be manufactured economically using the manufacturing method according to the example.

[0193]

[0194] Experimental Example 2: Preparation and Property Analysis of Li6PS5Cl

[0195] The results of the property analysis for Examples 1 and 2 and Comparative Examples 1 and 2 are shown in FIGS. 8 to 10.

[0196] Figure 8 is a comparison result of the Raman spectra when only Li2S was added to the ACN solvent during the manufacturing of the example, and when Li2S and P2S5 were added to the ACN solvent. Referring to Figure 8, when only Li2S was added to the ACN solvent, the radical (S3 ㆍ- ) was formed. When Li2S and P2S5 were added to ACN solvent, PS4 3- (Li3PS4) was formed. As a result, the ACN solvent reacts with Li2S to form a highly reactive radical (S3 ㆍ- ) is formed, and the radical increases the solubility of P2S5 and PS4 3- It was confirmed that (Li3PS4) can be formed. In addition, PS4 3- (Li3PS4) can react with LiCl to form azirodite-type Li6PS5Cl, so it was confirmed that azirodite-type Li6PS5Cl can be formed through the manufacturing method described in the examples.

[0197] Fig. 9 is an SEM image of an embodiment. Referring to Fig. 9, it was confirmed that Li6PS5Cl was manufactured using the manufacturing method according to the embodiment.

[0198] Fig. 10 is an XRD spectrum measured using CuKα rays for Examples and Comparative Examples 1 and 2. XRD measurements were performed under conditions of a diffraction angle (2θ) of 0° to 90°, a scan speed of 0.0167° / s, and a step size of 0.02° / step. Referring to Fig. 10, in the XRD spectrum for Examples, peaks appeared at the same diffraction angles as Comparative Example 2, and no peaks were observed at other diffraction angles. The XRD spectrum for the example included a sixth peak at a diffraction angle (2θ) of 15° and corresponding to the (111) plane, a seventh peak at a diffraction angle (2θ) of 18° and corresponding to the (200) plane, an eighth peak at a diffraction angle (2θ) of 25° and corresponding to the (220) plane, a ninth peak at a diffraction angle (2θ) of 29.5° and corresponding to the (311) plane, and a tenth peak at a diffraction angle (2θ) of 32° and corresponding to the (222) plane. The full widths at half maximum (FWHM) of the sixth, seventh, eighth, ninth, and tenth peaks were each 0.05° to 0.3°, and the difference from the full widths at half maximum of the peaks of Comparative Example 2 was 1% or less. On the other hand, in the XRD spectrum for Comparative Example 1, peaks were observed in the region where the diffraction angle (2θ) was 20° to 25°, and these were peaks that did not appear in the XRD spectra for Examples and Comparative Example 2, and were peaks for impurities. Thus, it was confirmed that Li6PS5Cl having a high purity of 98% or higher and without impurities could be produced using ACN solvent.

[0199] The example could be manufactured at a cost of 1% of that of Comparative Example 2. That is, it was confirmed that using the manufacturing method according to the example, Li6PS5Cl having high purity could be manufactured economically with less energy and less cost.

[0200]

[0201] Experimental Example 3: Electrochemical Characterization of Li6PS5Cl

[0202] The ionic conductivity of Examples 1 and 2 was evaluated.

[0203] Ionic conductivity was measured by electrochemical impedance spectroscopy (EIS) using a Solartron 1260 Impedance Analyzer at 25°C with an amplitude of 10 mV and a frequency of 0.01 mHz to 2 MHz. Ionic conductivity can be calculated by the following equation.

[0204] [ceremony]

[0205] Ionic conductivity [S / cm] = L / R A

[0206] L: Thickness of sample [cm]

[0207] R: DC resistance value obtained from impedance

[0208] A: Cross-sectional area of ​​the sample [cm 2 ]

[0209] For the ionic conductivity measurement, 50 mg of Li6PS5Cl according to Examples and Comparative Examples 1 and 2 was placed in a Li-blocking cell, flattened in a 10pi mold, and then the ionic conductivity was measured in a pressurized environment of 369 MPa. At this time, the sample had an average thickness of 410 μm and a cross-sectional area of ​​0.79 cm. 2 It was manufactured to be.

[0210] The results are shown in Fig. 11.

[0211] Referring to Fig. 11, the example had higher ionic conductivity than comparative example 1. In addition, it was confirmed that the example had excellent ionic conductivity of 2 mS / cm or more, like comparative example 2.

[0212]

[0213] While embodiments of the present invention have been described with reference to the attached drawings, the present invention may be implemented in other specific forms without altering the technical spirit or essential features thereof. Therefore, it should be understood that the embodiments described above are exemplary in all respects and are not limiting.

Claims

1. Forming Li2S; and Using the above Li2S, Li 7-a PS 6-a X a Including forming (0≤a≤2), Forming the above Li2S: Forming a mixture by mixing lithium sulfate (Li2SO4) and a carbon reducing agent; and Including heat treating the above mixture, wherein X comprises at least one of F, Cl, Br and I, Method for manufacturing a sulfide-based solid electrolyte.

2. In paragraph 1, The carbon reducing agent comprises at least one of glucose, sucrose, lactic acid, citric acid, methanol, formaldehyde, or a combination thereof. Method for manufacturing a sulfide-based solid electrolyte.

3. In paragraph 1, The lithium sulfate and the carbon reducing agent are mixed in a weight ratio of 1:0.33 to 1:

10. Method for manufacturing a sulfide-based solid electrolyte.

4. In paragraph 1, The above heat treatment includes performing a first heat treatment and performing a second heat treatment, The above first heat treatment is performed at a temperature of 200°C to 600°C, The above second heat treatment is performed at a temperature of 700°C to 1000°C. Method for manufacturing a sulfide-based solid electrolyte.

5. In paragraph 1, The above heat treatment is, wherein the carbon reducing agent reduces the lithium sulfate; and Including the formation of at least one of carbon monoxide or carbon dioxide, Method for manufacturing a sulfide-based solid electrolyte.

6. In paragraph 1, The method for manufacturing the above sulfide-based solid electrolyte further includes performing immersion, filtering, and drying on the product of the above heat treatment. Method for manufacturing a sulfide-based solid electrolyte.

7. In paragraph 1, The XRD spectrum measured using CuKα rays for the above Li2S is as follows: A first peak appears at a diffraction angle (2θ) in the range of 25° to 30°; A second peak appears at a diffraction angle (2θ) in the range of 30° to 35°; A third peak appears at a diffraction angle (2θ) ranging from 42° to 48°; A fourth peak appearing at a diffraction angle (2θ) ranging from 50° to 54°; and Contains a fifth peak appearing at a diffraction angle (2θ) in the range of 55° to 60°, The full width at half maximum (FWHM) of the first peak, the second peak, the third peak, the fourth peak, and the fifth peak is 0.05° to 0.3°. Method for manufacturing a sulfide-based solid electrolyte.

8. In paragraph 1, The purity of the above Li2S is 98% or more, Method for manufacturing a sulfide-based solid electrolyte.

9. In paragraph 1, Li above 7-a PS 6-a X a Forming (0≤a≤2) involves a wet process, Method for manufacturing a sulfide-based solid electrolyte.

10. In paragraph 1, Li above 7-a PS 6-a X a Forming (0≤a≤2) is, Preparing a precursor solution by mixing the above Li2S, phosphorus precursor, halide precursor and non-oxygenated solvent; and Comprising drying and heat treating the precursor solution, Method for manufacturing a sulfide-based solid electrolyte.

11. In paragraph 10, Li above 7-a PS 6-a X a Forming (0≤a≤2) is, forming radicals containing sulfur; and Dissolving the precursor with the above radical; including; Method for manufacturing a sulfide-based solid electrolyte.

12. In paragraph 10, The above phosphorus precursor comprises at least one of phosphorus pentasulfide (P2S5), red phosphorus, white phosphorus, diphosphorus pentoxide (P2O5), diammonium phosphate ((NH4)2HPO4), ammonium dihydrogen phosphate ((NH4)H2PO4), disodium phosphate (Na2HPO4), trisodium phosphate (Na3PO4), or a combination thereof. Method for manufacturing a sulfide-based solid electrolyte.

13. In paragraph 10, The above halide precursor is lithium halide, The lithium halide comprises at least one of LiF, LiCl, LiBr, LiI or a combination thereof. Method for manufacturing a sulfide-based solid electrolyte.

14. In paragraph 10, The non-oxygen solvent comprises at least one of acetonitrile, alkane, benzene, toluene, xylene, dichloromethane or a combination thereof. Method for manufacturing a sulfide-based solid electrolyte.

15. A sulfide-based solid electrolyte manufactured by the manufacturing method described in Article 1.

16. In paragraph 15, The XRD spectrum measured using CuKα rays for the above sulfide-based solid electrolyte is A sixth peak appears at a diffraction angle (2θ) ranging from 12° to 16°; A seventh peak appears at a diffraction angle (2θ) ranging from 17° to 20°; The eighth peak appears at a diffraction angle (2θ) ranging from 22° to 27°; A ninth peak appearing at a diffraction angle (2θ) ranging from 28° to 31°; and Contains a tenth peak appearing at a diffraction angle (2θ) in the range of 32° to 35°, The full width at half maximum (FWHM) of the sixth peak, the seventh peak, the eighth peak, the ninth peak, and the tenth peak is 0.05° to 0.3°. Sulfide-based solid electrolyte.

17. In paragraph 15, The purity of the above sulfide-based solid electrolyte is 98% or more. Sulfide-based solid electrolyte.

18. In paragraph 15, The ionic conductivity of the above sulfide-based solid electrolyte at 25°C is 2 mS / cm or more. Sulfide-based solid electrolyte.

19. Containing a positive electrode layer, a negative electrode layer, and a solid electrolyte layer, The above solid electrolyte layer comprises a sulfide-based solid electrolyte as described in claim 15. All-solid-state battery.

20. In paragraph 19, The ionic conductivity of the above sulfide-based solid electrolyte at 25°C is 2 mS / cm or more. All-solid-state battery.

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