Method for preparing solid electrolyte, solid electrolyte prepared thereby, and all-solid-state battery comprising same

Abstract

The present invention relates to a method for preparing a solid electrolyte, a solid electrolyte prepared thereby, and an all-solid-state battery comprising same. More specifically, the method comprises: providing particles including a sulfide-based solid electrolyte, wherein the sulfide-based solid electrolyte includes a first compound; providing onto the particles gas including a first fluorine-containing compound; and heat-treating the particles and the gas to form on the particles a shell including a second compound, wherein the second compound has a higher fluorine content than the first compound.

Description

Method for producing a solid electrolyte, a solid electrolyte produced thereby, and an all-solid-state battery comprising the same

[0001] The present invention relates to a method for producing a solid electrolyte, a solid electrolyte produced thereby, 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 solid electrolyte having excellent electrochemical stability and a method for manufacturing the same.

[0005] Another problem that the present invention seeks to solve is to provide an all-solid-state battery having excellent performance.

[0006] A method for manufacturing a solid electrolyte according to one embodiment of the present invention comprises: providing particles comprising a sulfide-based solid electrolyte, wherein the sulfide-based solid electrolyte comprises a first compound; providing a gas comprising a first fluorine-containing compound on the particles; and heat-treating the particles and the gas to form a shell comprising a second compound on the particles; wherein the second compound may have a higher fluorine content than the first compound.

[0007] According to one embodiment of the present invention, a solid electrolyte comprises: a core including a sulfide-based solid electrolyte, the sulfide-based solid electrolyte including a first compound; and a shell on the core; wherein the shell includes a second compound, the second compound having a higher fluorine content than the first compound, and the second compound may include at least one of a covalent bond between lithium (Li) and fluorine (F) and a covalent bond between phosphorus (P) and fluorine (F).

[0008] An all-solid-state battery according to one embodiment of the present invention includes a positive electrode layer, a negative electrode layer, and a solid electrolyte layer disposed between the positive electrode layer and the negative electrode layer, wherein the solid electrolyte layer may include the above-described solid electrolyte.

[0009] The method for manufacturing a solid electrolyte according to one embodiment of the present invention can be applied to sulfide-based solid electrolytes. Furthermore, using the method for manufacturing a solid electrolyte according to one embodiment of the present invention, an electrochemically stable sulfide-based solid electrolyte can be manufactured, the solid electrolyte can be mass-produced, and can be applied to materials with various structures.

[0010] A solid electrolyte according to one embodiment of the present invention can provide an all-solid-state battery having excellent electrochemical stability and excellent performance (impedance, lithium ion conductivity, lifespan, etc.).

[0011] Figure 1 is a cross-sectional view of an all-solid-state battery according to one embodiment of the present invention.

[0012] Figure 2 is a cross-sectional view of an all-solid-state battery according to one embodiment of the present invention.

[0013] FIG. 3 and FIG. 4 are a plan view and a cross-sectional view of an all-solid-state battery according to one embodiment of the present invention, respectively.

[0014] Figure 5 is a cross-sectional view of an all-solid-state battery according to one embodiment of the present invention.

[0015] FIG. 6 is a cross-sectional view of an all-solid-state battery including a gasket structure according to one embodiment of the present invention.

[0016] Figure 7 is an enlarged view illustrating a solid electrolyte according to embodiments of the present invention.

[0017] Figure 8 is a flowchart illustrating a method for manufacturing a solid electrolyte according to embodiments of the present invention.

[0018] Figures 9, 10 and 11 are schematic diagrams each illustrating each step of the manufacturing method.

[0019] Figures 12a to 12c are X-ray photoelectron spectroscopy results of solid electrolytes according to Example 1 and Comparative Example 1.

[0020] Figure 13 shows the oxidation current density results of an all-solid-state battery including a solid electrolyte according to Example 1 and Comparative Example 1 using cyclic voltammetry.

[0021] FIGS. 14a, 14b and 15a, 15b are X-ray photoelectron spectroscopy results of all-solid-state batteries containing solid electrolytes according to Comparative Example 1 and Example 1 after exposure to a constant potential, respectively.

[0022] Figures 16a and 16b show the reduction current density results of all-solid-state batteries including solid electrolytes according to Example 1 and Comparative Example 1 using cyclic voltammetry.

[0023] Figure 17 shows the capacity results according to voltage of an all-solid-state battery including a solid electrolyte according to Example 1 and Comparative Example 1.

[0024] Figure 18 shows the capacity results according to the number of cycles of an all-solid-state battery including a solid electrolyte according to Example 1 and Comparative Example 1.

[0025] Figures 19a and 19b are impedance spectroscopy results according to charge and discharge of an all-solid-state battery including a solid electrolyte according to Comparative Example 1 and Example 1, respectively.

[0026] Figures 20a and 20b are impedance spectroscopy results according to charge and discharge of all-solid-state batteries containing solid electrolytes according to Example 1 and Comparative Example 1, respectively. Figure 20c is capacity results according to voltage of all-solid-state batteries according to Example 1 and Comparative Example 1, respectively, as shown in Figures 20a and 20b.

[0027] 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.

[0028] 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.

[0029] 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.

[0030] 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.

[0031] As used herein, “combination thereof” may mean mixtures, laminates, composites, copolymers, alloys, blends, and reaction products of the components.

[0032] 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.

[0033]

[0034] Figure 1 is a cross-sectional view of an all-solid-state battery (10) according to one embodiment of the present invention.

[0035] 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).

[0036] 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.

[0037] 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.

[0038] 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).

[0039] 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.

[0040] 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.

[0041] 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 a sodium chloride type (NaCl type) structure, which is a type of crystal structure, and specifically refers to a structure in which face-centered cubic lattices (fcc) formed by cations and anions respectively are 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. 양극활물질(121)이 층상암염형 구조를 갖는 삼원계 리튬전이금속산화물을 포함하는 경우, 전고체 전지(10)의 에너지 밀도가 커지고 열안정성이 향상될 수 있다.

[0042] 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.

[0043] 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.

[0044] 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.

[0045] The solid electrolyte may have a particle shape. The solid electrolyte may be dispersed between the positive electrode active materials. 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).

[0046] 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-xI 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.

[0047] 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 is 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. Can be.

[0048] For example, the solid electrolyte included in the positive electrode active material layer (120) may be the same as the solid electrolyte included in the solid electrolyte layer (300) described later.

[0049] 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 (122-1) may be, for example, 15 GPa to 35 GPa.

[0050] 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.

[0051] 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.

[0052] 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.

[0053] 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 85 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 0.5 parts by weight or more and 1.5 parts by weight or less of the binder.

[0054] 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.

[0055] 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.

[0056] Referring to FIG. 1, the negative electrode layer (200) may include a negative electrode current collector (210) and a negative electrode coating layer (220) on the negative electrode current collector (210). The negative electrode current collector (210) may provide a reference surface on which the negative electrode 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 1 μm to 20 μm, more specifically, 5 μm to 15 μm, and more specifically, 7 μm to 10 μm.

[0057] 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.

[0058] The negative electrode coating layer (220) can allow lithium metal to grow between it and the negative electrode current collector (210) when the all-solid-state battery (10) is charged. The negative electrode coating layer (220) can act as a protective layer for the lithium metal and simultaneously suppress the precipitation and growth of lithium dendrites.

[0059] The cathode coating layer (220) may include a metal and carbon. For example, the cathode 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 cathode 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 cathode coating layer (220) may include a mixture of carbon black and silver (Ag).

[0060] The cathode coating layer (220) may further include additives other than metal and carbon. The cathode coating layer (220) may further include, for example, at least one additive selected from the group consisting of a binder, a filler, a coating agent, a dispersant, and an ion conductive additive.

[0061] The negative electrode coating layer (220) may have a smaller thickness than the positive electrode active material layer (120). The thickness of the negative electrode 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 negative electrode coating layer (220) 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 coating layer (220) is too thin, lithium dendrites formed between the negative electrode coating layer (220) and the negative electrode current collector (210) may collapse the negative electrode coating layer (220), thereby deteriorating the cycle characteristics of the first battery cell (CEL1). If the thickness of the cathode 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 cathode coating layer (220) may increase, thereby deteriorating the cycle characteristics of the first battery cell (CEL1).

[0062] Meanwhile, although not shown, a carbon layer may be further included to improve adhesion between the cathode coating layer (220) and the solid electrolyte layer (300).

[0063] Referring to FIG. 1, 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) will be described later with reference to FIG. 7.

[0064] 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 negative electrode coating layer (220).

[0065]

[0066] Figure 2 is a cross-sectional view of an all-solid-state battery (10) according to another embodiment of the present invention.

[0067] Referring to FIG. 2, the solid electrolyte layer (300) may include a first solid electrolyte layer (310) and a second solid electrolyte layer (320). The first solid electrolyte layer (310) may be adjacent to the positive electrode layer (100), and the second solid electrolyte layer (320) may be adjacent to the negative electrode layer (200).

[0068] The first solid electrolyte layer (310) and the second solid electrolyte layer (320) may have different thicknesses. The first solid electrolyte layer (310) may have a first thickness (TK1), and the second solid electrolyte layer (320) may have a second thickness (TK2). The first thickness (TK1) may be greater than the second thickness (TK2). For example, the first thickness (TK1) may be 2 to 100 times greater than the second thickness (TK2).

[0069]

[0070] Fig. 3 is a plan view of an all-solid-state battery (10) according to another embodiment of the present invention. Fig. 4 is a cross-sectional view taken along line A-A' of Fig. 3. In this embodiment, detailed descriptions of technical features overlapping with those previously described with reference to Figs. 1 and 2 will be omitted, and differences will be described in detail.

[0071] Referring to FIGS. 3 and 4, the area of ​​the anode layer (100) and the area of ​​the cathode layer (200) may be different from each other. 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).

[0072] In one embodiment of the present invention, the first solid electrolyte layer (310) may have substantially the same area as the positive electrode layer (100). The second solid electrolyte layer (320) may have substantially the same area as the negative electrode layer (200).

[0073] Specifically, the first solid electrolyte layer (310) may have a first width (WI1) in a first direction (D1). The second solid electrolyte layer (320) may have a second width (WI2) in the first direction (D1). The first width (WI1) may be smaller than the second width (WI2). The first solid electrolyte layer (310) may have a third width (WI3) in the second direction (D2). The second solid electrolyte layer (320) may have a fourth width (WI4) in the second direction (D2). The third width (WI3) may be smaller than the fourth width (WI4).

[0074] The all-solid-state battery (10) according to the present embodiment can be manufactured by forming a first laminate of a positive electrode layer (100) and a first solid electrolyte layer (310), forming a second laminate of a negative electrode layer (200) and a second solid electrolyte layer (320), and then laminating the first laminate and the second laminate.

[0075]

[0076] FIG. 5 is a cross-sectional view taken along line A-A' of FIG. 3 to explain an all-solid-state battery (10) according to another embodiment of the present invention.

[0077] Referring to FIG. 5, the negative electrode layer (200) of the all-solid-state battery (10) may further include a lithium metal layer (400) between the negative electrode current collector (210) and the negative electrode coating layer (220). The thickness of the lithium metal layer (400) may further increase when the all-solid-state battery (10) is charged. The negative electrode 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).

[0078] 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.

[0079] The lithium metal layer (400) may have a fifth width (WI5) in the first direction (D1). The fifth width (WI5) may be equal to or greater than the first width (WI1). The fifth width (WI5) may be equal to or less than the second width (WI2). For example, the fifth width (WI5) may be greater than the first width (WI1) and less than the second width (WI2).

[0080]

[0081] FIG. 6 is a cross-sectional view illustrating an all-solid-state battery according to another embodiment of the present invention.

[0082] Referring to FIG. 6, the all-solid-state battery (10) may include a gasket structure (500). The gasket structure (500) may fill in the step difference in the side surface of the all-solid-state battery (10) caused by the difference in the area of ​​the first laminate and the second laminate. The gasket structure (500) may surround the side surfaces of the first laminate of the all-solid-state battery (10) along the first and second directions (D1, D2). For example, the thickness of the gasket structure (500) may be substantially the same as the thickness of the first laminate. Accordingly, even when the first and second laminates having different areas are laminated and pressed, damage to the step difference in the side surface of the all-solid-state battery can be prevented. The term “substantially the same thickness” may be defined as a thickness that can prevent damage to the step difference in the side surface of the all-solid-state battery even when the first and second laminates having different areas are laminated and pressed.

[0083]

[0084] solid electrolyte

[0085] Fig. 7 is an enlarged view illustrating a solid electrolyte according to embodiments of the present invention. Fig. 7 is an enlarged view of area M of Fig. 1.

[0086] Referring to FIG. 7, a solid electrolyte according to embodiments of the present invention may include a core and a shell.

[0087] The particle size of the solid electrolyte may be 0.1 μm to 10 μm. In one embodiment, the particle size may refer to a diameter measured by randomly selecting about 30 solid electrolyte particles from an electron microscope photograph of the solid electrolyte.

[0088] The core (COR) may refer to the entire inner region excluding the shell (SHL) described later in the solid electrolyte.

[0089] The core (COR) 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.

[0090] The sulfide-based solid electrolyte may include a first compound. The first compound may be, for example, Li 7-x PS6-x Cl x (0≤x≤2), Li 7-x PS 6-x Br x (0≤x≤2), and Li 7-x PS 6- It may be an argyrodite-type compound including at least one selected from xIx(0≤x≤2). In particular, the first compound may be an argyrodite-type compound including at least one selected from Li6PS5Cl, Li6PS5Br, and Li6PS5I.

[0091] Alternatively, the first compound 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 is 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. Can be.

[0092] A shell (SHL) may be provided on a core (COR). The shell (SHL) may include a second compound. The second compound may have a higher content of fluorine (F) than the first compound.

[0093] The second compound may include a fluorine compound. The second compound may include a bond between an element constituting the sulfide-based solid electrolyte and fluorine (F). For example, the second compound may include a covalent bond (Li-F) between lithium (Li) and fluorine (F). For example, the second compound may include a covalent bond (PF) between phosphorus (P) and fluorine (F). For example, the second compound may include at least one of a covalent bond (Li-F) between lithium (Li) and fluorine (F) and a covalent bond (PF) between phosphorus (P) and fluorine (F).

[0094] For example, the second compound is LiF, Li x PO y F z and Li6PS5Cl x F 1-x It may include at least one selected from the group consisting of .

[0095] The second compound may have a wide electrochemical potential window. That is, the shell (SHL) may suppress electrochemical degradation of the core (COR) containing the sulfide-based solid electrolyte, thereby improving electrochemical stability, and an all-solid-state battery containing the same may have excellent performance.

[0096] The shell may further comprise LiCl and S in addition to the second compound.

[0097] The thickness of the shell (SHL) may be 50 nm or less. For example, the thickness of the shell (SHL) may be 10 nm to 50 nm. For example, the thickness of the shell (SHL) may be defined as the distance from the point where fluorine (F) on the core (COR) is observed through elemental analysis (EDS, line scanning) of each of 30 or so solid electrolyte particles randomly selected from a cryo-TEM image of the solid electrolyte to the outermost point of the shell (SHL). When the thickness of the shell (SHL) satisfies the above-described range, the solid electrolyte is electrochemically stable, and an all-solid-state battery including the same can have excellent performance.

[0098] 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.

[0099] The solid electrolyte according to embodiments of the present invention can have excellent electrochemical stability.

[0100] In the XPS spectrum after exposure to a static potential of 4.2 V to 5 V, the first compound has a first peak at a binding energy between 132 eV and 138 eV, and the second compound has a second peak at a binding energy between 132 eV and 138 eV, wherein the first peak may be greater than the second peak. The first peak and the second peak may correspond to oxidative phosphorus (oxidative P). The intensity of the first peak may be greater than 0. The intensity of the second peak may be about 0. That is, the second peak may not be substantially observed. In other words, even when exposed to a static potential of 4.2 V to 5 V, the second compound may have better electrochemical stability than the first compound. Thus, the solid electrolyte according to an embodiment of the present invention may have better electrochemical stability by having a shell including the second compound.

[0101]

[0102] Method for manufacturing solid electrolyte

[0103] Figure 8 is a flowchart illustrating a method for manufacturing a solid electrolyte according to embodiments of the present invention. Figures 9 to 11 are schematic diagrams illustrating each step of the manufacturing method.

[0104] Referring to FIG. 8, a method for manufacturing a solid electrolyte according to embodiments of the present invention may include: providing particles including a sulfide-based solid electrolyte; providing a first fluorine-containing compound on the particles; and heat-treating the particles and the first fluorine-containing compound to form a shell on the particles.

[0105]

[0106] Referring to FIG. 9, particles (PTC) including a sulfide-based solid electrolyte can be provided (S100). The sulfide-based solid electrolyte can 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 can be performed after the treatment. The solid electrolyte can be amorphous, crystalline, or a mixture thereof. In addition, the solid electrolyte can be, for example, a material including sulfur (S), phosphorus (P), and lithium (Li) as at least constituent elements among the above-described sulfide-based solid electrolyte materials. For example, the solid electrolyte can be a material including Li2S-P2S5.

[0107] The sulfide-based solid electrolyte may include a first compound. The first compound may be, 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- It may be an argyrodite-type compound including at least one selected from xIx(0≤x≤2). In particular, the first compound may be an argyrodite-type compound including at least one selected from Li6PS5Cl, Li6PS5Br, and Li6PS5I.

[0108] Alternatively, the first compound 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 is 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. Can be.

[0109]

[0110] Referring to FIG. 10, a first fluorine-containing compound can be provided on a particle (PTC) (S300).

[0111] For example, providing a first fluorine-containing compound on a particle (PTC) may include providing a gas (G) comprising the first fluorine-containing compound on the particle (PTC). The gas (G) comprising the first fluorine-containing compound may include at least one selected from the group consisting of F2, NF3, ClF3, F2 / Ar, F2 / He, and F2 / N2.

[0112] For example, providing a gas (G) comprising a first fluorine-containing compound may include pyrolyzing a solid comprising a second fluorine-containing compound. For example, the second fluorine-containing compound may include an inorganic fluorine compound. For example, the second fluorine-containing compound may include at least one selected from the group consisting of NH4F, NH4FHF, XeF2, TbF4, AgF, AgF2, CuF, AlF3, ZnF2, and FeF3.

[0113] The mass ratio of the first compound and the second fluorine-containing compound may be from 50:1 to 200:1. For example, the mass ratio of the first compound and the second fluorine-containing compound may be from 50:1 to 150:1, or 100:1. When the mass ratio of the first compound and the second fluorine-containing compound satisfies the range described above, the molar ratio of the first compound and the first fluorine-containing compound can be adjusted to a desired range as described below.

[0114] The thermal decomposition can be carried out at a temperature of 25°C to 150°C. For example, the thermal decomposition can be carried out at a temperature of 50°C to 150°C, 50°C to 125°C, or 50°C to 100°C. When the thermal decomposition temperature satisfies the above-described range, a solid containing the second fluorine-containing compound can be thermally decomposed to provide a gas containing the first fluorine-containing compound, and the molar ratio of the first compound and the first fluorine-containing compound can be controlled to a desired range as described below.

[0115] As another example, providing the first fluorine-containing compound on the particle (PTC) may include utilizing RF plasma. The RF plasma may utilize a third fluorine-containing compound. For example, the RF plasma may utilize CF4 or the like.

[0116] As another example, providing the first fluorine-containing compound on the particle (PTC) may include using atomic layer deposition. The atomic layer deposition may utilize a fourth fluorine-containing compound. For example, the atomic layer deposition may utilize AlF3.

[0117] As another example, providing the first fluorine-containing compound on the particle (PTC) may include thermally decomposing the 53rd fluorine-containing compound. As an example, the fifth fluorine-containing compound may include a fluorinated polymer. For example, the fifth fluorine-containing compound may include poly(vinylidene fluoride), poly(vinylidene fluoride-co-hexafluoropropylene), poly(tetrafluoroethylene), CYTOP, and the like.

[0118] Providing the first fluorine-containing compound on the particle (PTC) may include adjusting the molar ratio of the first compound and the first fluorine-containing compound to be 50:1 to 100:1. For example, the molar ratio of the first compound and the fluorine-containing compound may be 50:1 to 75:1, or 55:1 to 65:1. When the molar ratio of the first compound and the fluorine-containing compound satisfies the range described above, a solid electrolyte having a desired shell thickness can be manufactured.

[0119]

[0120] Referring to FIG. 11, the particle (PTC) and the first fluorine-containing compound can be heat-treated to form a shell (SHL) including a second compound on the particle (PTC) (S500).

[0121] The heat treatment may be performed at a temperature of 25°C to 150°C. For example, the heat treatment may be performed at a temperature of 50°C to 150°C, 50°C to 150°C, 50°C to 125°C, or 50°C to 100°C. When the heat treatment temperature satisfies the above-described range, the sulfide-based solid electrolyte and the first fluorine-containing compound can chemically react with each other, and a shell (SHL) can be sufficiently formed on the core (COR).

[0122] The heat treatment can be performed for 10 minutes to 12 hours. For example, the heat treatment can be performed for 30 minutes to 12 hours, 1 hour to 12 hours, 1 hour to 6 hours, or 1 hour to 3 hours. When the heat treatment time satisfies the above-described range, the sulfide-based solid electrolyte and the first fluorine-containing compound can chemically react with each other to form a second compound, and a shell (SHL) can be sufficiently formed on the core (COR).

[0123] Accordingly, a solid electrolyte including a core (COR) and a shell (SHL) can be manufactured. The core (COR) may include a first compound, and the shell (SHL) may include a second compound. The second compound may have a higher fluorine (F) content than the first compound. The second compound may include a bond between an element constituting a sulfide-based solid electrolyte and fluorine (F). For example, the second compound may include a covalent bond (Li-F) between lithium (Li) and fluorine (F). For example, the second compound may include a covalent bond (PF) between phosphorus (P) and fluorine (F). For example, the second compound may include at least one of a covalent bond (Li-F) between lithium (Li) and fluorine (F) and a covalent bond (PF) between phosphorus (P) and fluorine (F).

[0124]

[0125] The method for manufacturing a solid electrolyte according to embodiments of the present invention may further include, after forming the shell, removing a gas (G) containing the unreacted first fluorine-containing compound. The method for manufacturing a solid electrolyte according to embodiments of the present invention may further include, after forming the shell, cooling to room temperature. For example, the room temperature may include a temperature of 20°C to 30°C. Thus, a solid electrolyte including the core (COR) and shell (SHL) described above may be manufactured.

[0126]

[0127] 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.

[0128]

[0129] Example 1

[0130] A solid electrolyte including a core and a shell was prepared (hereinafter, F-LPSCl). The solid electrolyte was prepared using the following method.

[0131] Li6PS5Cl particles were prepared in a first container (S100). XeF2 was prepared in a second container (S300). Both the first container and the second container were heat-treated at 60°C for 2 hours (S500). Thereafter, unreacted gas was removed. The mass ratio of the Li6PS5Cl particles and XeF2 was 100:1. The molar ratio of the Li6PS5Cl particles and F2 was 63:1. Thus, a solid electrolyte including a core and a shell was manufactured. The core included Li6PS5Cl, and the shell included a second compound including at least one of a Li-F bond and a PF bond on the surface of the core. The thickness of the shell was 37.3 nm.

[0132]

[0133] Comparative Example 1

[0134] Li6PS5Cl particles were prepared (hereinafter, LPSCl).

[0135]

[0136] Manufacturing of all-solid-state batteries

[0137] (1) Preparation of cathode layer

[0138] Li as a negative electrode active material 0.5 In was prepared. Li6PS5Cl solid electrolyte, which is an argyrodite-type crystal, was used as a solid electrolyte. The negative active material composition, mixed in a weight ratio of negative active material:solid electrolyte = 8:2, was molded into a powder form.

[0139]

[0140] (2) Preparation of the anode layer

[0141] LiNi as a cathode active material 0.8 Co 0.15 Mn 0.15 O2(NCM) was prepared. Li6PS5Cl solid electrolyte, which is an argyrodite-type crystal, was used as a solid electrolyte. Carbon black (CB) was prepared as a conductive agent. The positive electrode active material composition, mixed in a weight ratio of positive electrode active material: solid electrolyte: carbon black = 70:30:3, was molded into powder form.

[0142]

[0143] (3) Manufacturing of all-solid-state batteries

[0144] 150 mg of solid electrolyte Li6PS5Cl, which is an argyrodite-type crystal, was loaded into a mold cell and then pelletized at a pressure of 70 MPa.

[0145] 20 mg of the prepared positive electrode layer was loaded onto one side of the solid electrolyte pellet, and 100 mg of the prepared negative electrode layer was loaded onto the other side. By pressurizing them at a pressure of 370 MPa, an all-solid-state half-cell was manufactured.

[0146]

[0147] Experimental Example 1: Structural Analysis of Solid Electrolyte

[0148] Figures 12a to 12c are X-ray photoelectron spectroscopy results of solid electrolytes according to Example 1 and Comparative Example 1.

[0149] Referring to FIGS. 12a to 12c, unlike the solid electrolyte according to Comparative Example 1, the solid electrolyte according to Example 1 was confirmed to have a core and shell structure by forming a fluorine compound including a bond with fluorine (F) on the surface of the sulfide-based solid electrolyte through the S300 and S500 steps. The first compound constituting the core of Example 1 was Li6PS5Cl. The second compound constituting the shell of Example 1 was LiF, Li x PO y F z and Li6PS5Cl x F 1-x . Additionally, the shell also contained LiCl and S.

[0150]

[0151] Experimental Example 2: Electrochemical Stability Evaluation

[0152] Figure 13 shows the oxidation current density results of all-solid-state batteries including solid electrolytes according to Example 1 and Comparative Example 1 using cyclic voltammetry. The oxidation current density was measured at a cyclic rate of 0.5 mV / s in a voltage range of 3.0 V to 4.5 V.

[0153] Referring to Fig. 13, compared to Comparative Example 1, the oxidation current density of the all-solid-state battery including the solid electrolyte according to Example 1 was reduced.

[0154]

[0155] Figures 14a, 14b and 15a, 15b respectively show the results of X-ray photoelectron spectroscopy of all-solid-state batteries containing solid electrolytes according to Comparative Example 1 and Example 1 after exposure to a constant potential. The constant potential exposure was performed for 1 hour.

[0156] Referring to FIGS. 14a, 14b and 15a, 15b, unlike Comparative Example 1 (LPSCl), in Example 1, a peak corresponding to the oxidized form of phosphorus (oxidative P) was observed at a binding energy between 132 eV and 138 eV when exposed to a constant potential of 4.5 V. This confirmed that the all-solid-state battery including the solid electrolyte according to Example 1 had excellent oxidation stability even when exposed to a constant potential.

[0157]

[0158] Figures 16a and 16b show the reduction current density results of all-solid-state batteries including solid electrolytes according to Example 1 and Comparative Example 1 using cyclic voltammetry. The reduction current density was measured at a cyclic rate of 0.5 mV / s in a voltage range of 0 V to 2.5 V.

[0159] Referring to FIGS. 16a and 16b, the reduction current density of the all-solid-state battery including the solid electrolyte according to Example 1 was reduced compared to Comparative Example 1.

[0160]

[0161] Fig. 17 shows the capacity results according to voltage of the all-solid-state battery including the solid electrolyte according to Example 1 and Comparative Example 1. Fig. 18 shows the capacity results according to the number of cycles of the all-solid-state battery including the solid electrolyte according to Example 1 and Comparative Example 1. Figs. 19a, 19b, 20a, 20b, and 20c are the impedance spectroscopy results according to charge and discharge of the all-solid-state battery including the solid electrolyte according to Example 1 and Comparative Example 1.

[0162] Figures 17 and 18 were measured under the following conditions.

[0163] Voltage range: 3.0V to 4.3V

[0164] Charge / discharge rate: 0.33C (CC / CV)

[0165] Operating temperature: 30℃

[0166] Figures 19a, 19b, 20a, 20b and 20c were measured under the following conditions.

[0167] Voltage range: 3.0V to 4.3V

[0168] Charge / discharge rate: 0.1C (CC)

[0169] Operating temperature: 30℃

[0170] Referring to FIGS. 17, 18, 19a, 19b, 20a, 20b and 20c, it was confirmed that, compared to Comparative Example 1, even when the all-solid-state battery including the solid electrolyte according to Example 1 was repeatedly charged and discharged, the increase in impedance was suppressed and the lifespan was extended.

[0171]

[0172] Accordingly, it was confirmed that the solid electrolyte according to Example 1 has excellent electrochemical stability.

[0173]

[0174] 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. Providing particles comprising a sulfide-based solid electrolyte, wherein the sulfide-based solid electrolyte comprises a first compound; Providing a gas comprising a first fluorine-containing compound on the particles; and heat-treating the particles and the gas to form a shell containing a second compound on the particles; The second compound has a higher fluorine content than the first compound, Method for manufacturing solid electrolyte.

2. In paragraph 1, The above first compound is 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- Comprising an argyrodite-type compound comprising at least one selected from xIx(0≤x≤2), Method for manufacturing solid electrolyte.

3. In paragraph 1, The gas containing the first fluorine-containing compound comprises at least one selected from the group consisting of F2, NF3, ClF3, F2 / Ar, F2 / He and F2 / N2. Method for manufacturing solid electrolyte.

4. In paragraph 1, Providing a gas comprising the first fluorine-containing compound comprises thermally decomposing a solid comprising the second fluorine-containing compound. Method for manufacturing solid electrolyte.

5. In paragraph 4, The second fluorine-containing compound comprises at least one selected from the group consisting of NH4F, NH4FHF, XeF2, TbF4, AgF, AgF2, CuF, AlF3, ZnF2, and FeF3. Method for manufacturing solid electrolyte.

6. In paragraph 4, The above thermal decomposition is carried out at a temperature of 50℃ to 150℃. Method for manufacturing solid electrolyte.

7. In paragraph 4, Providing the above gas, the mass ratio of the first compound and the second fluorine-containing compound is 50:1 to 200:1, Method for manufacturing solid electrolyte.

8. In paragraph 1, Providing the gas comprises adjusting the molar ratio of the first compound and the first fluorine-containing compound to be 50:1 to 100:

1. Method for manufacturing solid electrolyte.

9. In paragraph 1, The second compound comprises at least one of a covalent bond between lithium (Li) and fluorine (F) and a covalent bond between phosphorus (P) and fluorine (F). Method for manufacturing solid electrolyte.

10. In paragraph 1, The above heat treatment is performed at a temperature of 50°C to 150°C. Method for manufacturing solid electrolyte.

11. In paragraph 1, The above heat treatment is carried out for 1 to 6 hours. Method for manufacturing solid electrolyte.

12. In paragraph 1, After forming the shell, further comprising removing a gas containing the unreacted first fluorine-containing compound. Method for manufacturing solid electrolyte.

13. A core comprising a sulfide-based solid electrolyte, wherein the sulfide-based solid electrolyte comprises a first compound; and A shell on the core; including, The above shell comprises a second compound, The second compound has a higher fluorine content than the first compound, The second compound comprises at least one of a covalent bond between lithium (Li) and fluorine (F) and a covalent bond between phosphorus (P) and fluorine (F). Solid electrolyte.

14. In paragraph 13, The above first compound is 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- Comprising an argyrodite-type compound comprising at least one selected from xIx(0≤x≤2), Solid electrolyte.

15. In paragraph 13, The thickness of the above shell is 50 nm or less, Solid electrolyte.

16. In paragraph 13, The second compound is LiF, Li x PO y F z and Li6PS5Cl x F 1-x Containing at least one selected from the group consisting of Solid electrolyte.

17. In paragraph 13, The above shell further comprises LiCl and S, Solid electrolyte.

18. In paragraph 13, In the XPS spectra after exposure to a potential of 4.2 V to 5 V, The first compound has a first peak at a binding energy between 132 eV and 138 eV, The second compound has a second peak at a binding energy between 132 eV and 138 eV, The first peak is larger than the second peak, Solid electrolyte.

19. Including a positive electrode layer, a negative electrode layer, and a solid electrolyte layer disposed between the positive electrode layer and the negative electrode layer, The solid electrolyte layer comprises the solid electrolyte described in claim 13. All-solid-state battery.

20. In paragraph 19, The above positive electrode layer includes a positive electrode current collector and a positive electrode active material layer disposed on the positive electrode current collector, The above cathode active material layer includes a cathode active material, a solid electrolyte, a conductive material, and a binder. The solid electrolyte included in the positive electrode active material layer includes the solid electrolyte described in claim 13. All-solid-state battery.

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