Method for manufacturing solid electrolyte, solid electrolyte manufactured using same, and all-solid-state battery comprising same

Abstract

The present invention relates to a method for manufacturing a solid electrolyte, a solid electrolyte manufactured using same, and an all-solid-state battery comprising same. More specifically, the method comprises: dry-mixing sulfide-based solid electrolyte raw materials to form a mixture; performing a first heat treatment process on the mixture at a first temperature to form first particles; adding the first particles to a solvent and milling same to form second particles; drying the second particles to form third particles; and performing a second heat treatment process on the third particles at a second temperature, wherein the second temperature is lower than the first temperature.

Description

A method for manufacturing a solid electrolyte, a solid electrolyte manufactured using the same, and an all-solid-state battery including the same

[0001] The present invention relates to a method for producing a sulfide-based solid electrolyte, a sulfide-based solid electrolyte produced using 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 have been proposed, replacing the electrolyte in lithium-ion batteries with a solid electrolyte. By eliminating the use of liquid electrolytes, 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 offer superior safety.

[0004] The problem to be solved by the present invention is to provide a method for manufacturing a solid electrolyte with improved solvent stability.

[0005] Another problem to be solved by the present invention is to provide a solid electrolyte with improved solvent stability.

[0006] Another problem that the present invention seeks to solve is to provide an all-solid-state battery having excellent performance.

[0007] According to the concept of the present invention, a method for manufacturing a solid electrolyte includes dry mixing sulfide-based solid electrolyte raw materials to form a mixture; performing a first heat treatment process on the mixture at a first temperature to form first particles; immersing the first particles in a solvent and milling them to form second particles; drying the second particles to form third particles; and performing a second heat treatment process on the third particles at a second temperature, wherein the second temperature may be lower than the first temperature.

[0008] According to another concept of the present invention, a solid electrolyte can be manufactured by the above-described manufacturing method. When 0.2 g of the solid electrolyte is immersed in 3 g of a colorless and transparent non-polar solvent at room temperature and left for 10 days, when UV / Vis absorbance is measured in the wavelength range of 240 to 800 nm for the non-polar solvent, the height of the peak appearing in the wavelength range of 240 to 350 nm may be 1.0 (au) or less.

[0009] An all-solid-state battery according to another concept of the present invention comprises a positive electrode, a negative electrode, and a solid electrolyte layer, wherein the solid electrolyte layer may include the above-described solid electrolyte.

[0010] Using a solid electrolyte manufacturing method according to one embodiment of the present invention, a sulfide-based solid electrolyte with a reduced content of surface byproducts can be manufactured. This can improve the solvent stability of the solid electrolyte.

[0011] A solid electrolyte according to another embodiment of the invention may have improved solvent stability.

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

[0015] 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.

[0016] Figure 5 is a cross-sectional view of an all-solid-state battery according to one embodiment of the present invention.

[0017] 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.

[0018] Figure 7 is a flowchart illustrating a method for manufacturing a solid electrolyte according to embodiments of the present invention.

[0019] Figure 8 is a drawing showing the color change after immersing a solid electrolyte according to examples and comparative examples of the present invention in a solvent.

[0020] FIG. 9 is an X-ray diffraction (XRD) graph for a solvent in which a solid electrolyte according to an embodiment and a comparative example of the present invention is immersed.

[0021] Figure 10 is a graph showing the change in ionic conductivity before and after solvent immersion of a solid electrolyte according to an embodiment and comparative example of the present invention.

[0022] Figure 11 is an X-ray photoelectron spectroscopy (XPS) graph of a solid electrolyte before and after solvent immersion according to an embodiment and a comparative example of the present invention.

[0023]

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

[0031] 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).

[0032] 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.

[0033] 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.

[0034] 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).

[0035] The cathode active material layer (120) may include a cathode active material, a solid electrolyte, a conductive material, and a binder.

[0036] 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.

[0037] 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.

[0038] 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. 양극활물질이 층상암염형 구조를 갖는 삼원계 리튬전이금속산화물을 포함하는 경우, 전고체 전지(10)의 에너지 밀도가 커지고 열안정성이 향상될 수 있다.

[0039] 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.

[0040] 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.

[0041] 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.

[0042] 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).

[0043] 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.

[0044] 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.

[0045] Alternatively, the solid electrolyte may be a solid electrolyte manufactured by a solid electrolyte manufacturing method described later.

[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 can be 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 median particle size (D50) smaller than the solid electrolyte (SE) 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 (SE) 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) includes 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.

[0049] 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.

[0050] 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, polyvinylidene fluoride / hexafluoropropylene copolymer, polyacrylonitrile, and polymethyl methacrylate.

[0051] 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.

[0052] 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.

[0053] 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.

[0054] For example, the cathode active material layer (120) may further include a lithium salt. The lithium salt may be the same as or different from the lithium salt (LTS) included in the solid electrolyte layer (300) described below.

[0055] Referring to FIG. 1, the negative electrode layer (200) includes a negative electrode current collector (210) and a negative electrode active material layer (220) disposed on the negative electrode current collector (210). The negative electrode active material layer (220) may include a negative electrode active material and a binder.

[0056] The negative electrode current collector (210) can provide a reference surface on which the negative electrode active material layer (220) is arranged. The negative electrode current collector (210) can include, for example, a material that does not react with lithium, i.e., does not form an alloy or compound with lithium. The material constituting the negative electrode current collector (210) is not necessarily limited to, for example, copper (Cu), stainless steel, titanium (Ti), iron (Fe), cobalt (Co), and nickel (Ni), and any material that can be used as an electrode current collector can be used. The thickness of the negative electrode current collector can be 1 to 20 μm, for example, 5 to 15 μm, for example, 7 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) is, for example, in the form of a plate or foil. Meanwhile, in one embodiment, the negative electrode current collector (210) may be omitted.

[0058] The negative electrode active material included in the negative electrode active material layer (220) 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.

[0059] 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.

[0060] 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.

[0061] The metal or metalloid negative electrode active material includes, but is not necessarily 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.

[0062] The negative electrode active material layer (220) 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 (220) 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).

[0063] In one embodiment, the negative electrode active material layer (220) 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.

[0064] The binder included in the negative electrode active material layer (220) is, for example, styrene butadiene rubber (SBR), polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, vinylidene fluoride / hexafluoropropylene copolymer, polyvinylidene 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.

[0065] Since the negative electrode active material layer (220) includes a binder, the negative electrode active material layer (220) can be stably formed on the negative electrode current collector (210). That is, the bonding strength between the negative electrode active material layer (220) and the negative electrode current collector (210) can be increased. In addition, cracking of the negative electrode active material layer (220) is suppressed despite changes in the volume and / or relative positions of the negative electrode active material layer (220) during the charge and discharge process. If the negative electrode active material layer (220) does not include a binder, the negative electrode active material layer (220) can be easily separated from the negative electrode current collector (210). As the negative electrode active material layer (220) 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.

[0066] The negative electrode active material layer (220) is manufactured, for example, by providing a mixture in which the materials constituting the negative electrode active material layer (220) are dispersed onto the negative electrode current collector (210). Since a binder is included in the materials constituting the negative electrode active material layer (220), 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.

[0067] The negative electrode active material layer (220) may further include other additives in addition to the negative electrode active material and binder. The negative electrode active material layer (220) may further include, for example, fillers, coating agents, dispersants, ion conductive additives, etc.

[0068] The negative electrode active material layer (220) may have a smaller thickness than the positive electrode active material layer (120). The thickness of the negative electrode active material 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 active material 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 active material layer (220) is too thin, lithium dendrites formed between the negative electrode active material layer (220) and the negative electrode current collector (210) may collapse the negative electrode active material layer (220), thereby deteriorating the cycle characteristics of the all-solid-state battery (10). If the thickness of the negative electrode active material 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 negative electrode active material layer (220) may increase, thereby deteriorating the cycle characteristics of the all-solid-state battery (10).

[0069] If the thickness of the negative electrode active material layer (220) decreases, the charge capacity of the negative electrode active material layer (220) may also decrease, for example. The charge capacity of the negative electrode active material layer (220) 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 (220) 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 (220) is excessively small, the thickness of the negative electrode active material layer (220) becomes very thin, and the same defects as the defects described above that occur when the thickness of the negative electrode active material layer (220) becomes excessively thin may occur. If the charge capacity of the negative electrode active material layer (220) increases excessively, the same defects as the defects described above that occur when the thickness of the negative electrode active material layer (220) increases excessively may occur.

[0070] For example, 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 in 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 (220) can also be calculated in the same way. That is, the charge capacity of the negative electrode active material layer (220) 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 (220). When the negative electrode active material layer (220) 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 (220). 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 (220) 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 (220) means the initial charge capacity measured at the time of the first cycle charge.

[0071] Meanwhile, although not shown, a carbon layer may be further included to improve adhesion between the negative electrode active material layer (220) and the solid electrolyte layer (300).

[0072] A solid electrolyte layer (300) may be provided between the positive electrode layer (100) and the negative electrode layer (200). The solid electrolyte layer (300) may include a sulfide-based solid electrolyte having excellent lithium ion conductivity characteristics. The solid electrolyte in the solid electrolyte layer (300) may be the same as or different from the solid electrolyte included in the positive electrode active material layer (120) described above. In addition, the solid electrolyte included in the solid electrolyte layer (300) may be manufactured by a solid electrolyte manufacturing method described below.

[0073] In one embodiment, the solid electrolyte included in the solid electrolyte layer (300) may be amorphous, crystalline, or a mixture thereof. In addition, the solid electrolyte may be, for example, a sulfide-based solid electrolyte material that includes at least sulfur (S), phosphorus (P), and lithium (Li) as constituent elements. For example, the solid electrolyte may be a material including Li2S-P2S5. When using a sulfide-based solid electrolyte material that includes 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.

[0074] 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.

[0075] Alternatively, the sulfide-based solid electrolyte is Li 7-a M a PS6-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.

[0076] 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.

[0077] 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, and the like, but is not limited thereto. For example, the binder may include at least one selected from the group consisting of styrene butadiene rubber, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polyvinyl alcohol, vinylidene fluoride / hexafluoropropylene copolymer, polyvinylidene fluoride / hexafluoropropylene copolymer, polyacrylonitrile, and polymethyl methacrylate. 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 active material layer (220).

[0078]

[0079] Figure 2 is a cross-sectional view of an all-solid-state battery (10) according to another embodiment of the present invention.

[0080] 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).

[0081] 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).

[0082]

[0083] 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.

[0084] 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).

[0085] 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).

[0086] 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).

[0087] 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.

[0088]

[0089] FIG. 5 is a cross-sectional view taken along line A-A' of FIG. 3 to explain an all-solid-state battery according to another embodiment of the present invention.

[0090] 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).

[0091] 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.

[0092] 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).

[0093]

[0094] FIG. 6 is a cross-sectional view illustrating an all-solid-state battery according to another embodiment of the present invention.

[0095] Referring to FIG. 6, the all-solid-state battery (10) may include a gasket structure (400). The gasket structure (400) 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 (400) 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 (400) 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.

[0096]

[0097] Hereinafter, a method for manufacturing a solid electrolyte according to embodiments of the present invention and a solid electrolyte manufactured thereby will be described in more detail.

[0098] The solid electrolyte according to embodiments of the present invention may be an argyrodite-type compound. The solid electrolyte 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-x I x(0≤x≤2) may be an argyrodite-type compound including at least one selected from. In particular, the solid electrolyte according to the present invention may be an argyrodite-type compound including at least one selected from Li6PS5Cl, Li6PS5Br and Li6PS5I. 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 is, for example, 15 GPa to 35 GPa.

[0099] The average particle diameter (D50) of the solid electrolyte is not particularly limited, but may be from 0.01 μm to 30 μm. In one embodiment, the average particle diameter (D50) of the solid electrolyte may be from 0.5 μm to 10 μm, from 1.0 μm to 5 μm, or from 2.0 μm to 4.0 μm.

[0100]

[0101] Figure 7 is a flowchart illustrating a method for manufacturing a solid electrolyte membrane according to embodiments of the present invention.

[0102] Referring to FIG. 7, a method for manufacturing a solid electrolyte may include dry mixing sulfide-based solid electrolyte raw materials to form a mixture (S100), performing a first heat treatment process on the mixture at a first temperature to form first particles (S200), putting the first particles into a solvent and milling them to form second particles (S300), drying the second particles to form third particles (S400), and performing a second heat treatment process on the third particles at a second temperature (S500).

[0103] The sulfide-based solid electrolyte raw material may include a sulfur precursor, a phosphorus precursor, and a LiX precursor, wherein X may be a halogen element. Specifically, the sulfide-based solid electrolyte raw material includes Li2S, P2S5, and LiX, and wherein X may be F, Cl, Br, or I. Each of the sulfide-based solid electrolyte raw materials may be provided in a powder form after undergoing a pulverization process.

[0104] The provided sulfide-based solid electrolyte raw materials can be mixed to form a mixture (S100). The raw material mixing can be performed dry, without the use of solvents or the like. The mixing method is not particularly limited, but may include mechanical milling. Mechanical milling includes, but is not limited to, a ball mill, a jet mill, etc., and any method capable of performing mechanical mixing within the relevant technical field is acceptable.

[0105] The mechanical milling can be performed dry, for example, in an inert atmosphere for 10 to 1000 hours, 10 to 100 hours, or 10 to 30 hours. The mechanical milling can be performed dry, for example, in an inert atmosphere at a speed of 300 rpm to 10,000 rpm, 350 rpm to 5,000 rpm, or 370 rpm to 1,000 rpm. The inert atmosphere can be an atmosphere substantially free of oxygen. The inert atmosphere can be an atmosphere comprising, for example, nitrogen, argon, neon, or a combination thereof.

[0106]

[0107] A first heat treatment process can be performed on the mixture at a first temperature to form a sulfide-based solid electrolyte precursor, i.e., first particles (S200). The first heat treatment process can be performed under an inert atmosphere. The inert atmosphere can be a nitrogen atmosphere and / or an argon atmosphere.

[0108] The first temperature may be 300°C to 600°C, or 400°C to 550°C, or 500°C to 550°C. The first heat treatment process may be performed for 2 hours to 50 hours, 3 hours to 40 hours, or 5 hours to 15 hours. When the first temperature and the time of the first heat treatment process satisfy the above ranges, the first particles may have a high crystallinity.

[0109] The average particle diameter (D50) of the first particles that have completed the first heat treatment process may be 0.1 μm to 500 μm, 0.5 μm to 100 μm, or 1.0 μm to 50 μm.

[0110] The first particles can be introduced into a solvent and milled to form the second particles (S300). The milling can be performed using a planetary mill, for example, a planetary mill containing zirconia (Zr) balls.

[0111] The solvent may be a nonpolar solvent, and may include, for example, at least one selected from the group consisting of xylene, benzene, toluene, pentane, hexane, cyclohexane, and octyl acetate. When a nonpolar solvent is used as the solvent, side reactions between the solid electrolyte precursor and the solvent can be minimized.

[0112] During the milling process, a dispersant may be added to the solvent. The type of dispersant is not particularly limited, and examples of dispersants include octyl acetate and butyl acetate.

[0113] Milling under a solvent can be performed for, for example, 1 to 10 hours, 3 to 8 hours, or 5 to 8 hours. Milling can be performed wet, for example, at a speed of 300 rpm to 10,000 rpm, 350 rpm to 5,000 rpm, or 370 rpm to 1,000 rpm.

[0114] Wet milling can be used to reduce the size of the solid electrolyte particles to a size suitable for use in the positive active material layer or the solid electrolyte layer. The average particle diameter (D50) of the second particles may be from 0.01 μm to 30 μm. In one embodiment, the average particle diameter (D50) of the solid electrolyte may be from 0.5 μm to 10 μm, from 1.0 μm to 5 μm, or from 2.0 μm to 4.0 μm.

[0115]

[0116] The second particles can be dried to form third particles (S400). The solvent within the second particles can be removed through the drying process. The drying temperature can be 50°C to 250°C, 60°C to 200°C, or 70°C to 150°C. The drying process can be performed in a dryer. For example, the dryer can include a vacuum oven or the like. That is, the drying process can be performed in a vacuum oven or the like.

[0117]

[0118] A second heat treatment process can be performed on the third particles at a second temperature to form solid electrolyte particles (S500). By performing an additional heat treatment process after the drying process, impurities remaining in the solid electrolyte particles, such as sulfur (S), can be effectively removed.

[0119] The second temperature may be lower than the first temperature. For example, the second temperature may be between 200°C and 400°C, or between 200°C and 300°C, or between 250°C and 300°C. When the second temperature satisfies the above-described range, byproducts remaining in the third particles can be sufficiently removed, while solid electrolyte particles pulverized through milling can be prevented from re-agglomerating.

[0120] The second heat treatment process may be performed for 2 to 10 hours, 3 to 6 hours, or 4 to 5 hours. When the time of the second heat treatment process satisfies the above-described range, byproducts remaining in the third particles can be sufficiently removed, and the solvent stability of the solid electrolyte can be improved.

[0121] The second heat treatment process may be performed under an inert atmosphere. The inert atmosphere may be a nitrogen atmosphere and / or an argon atmosphere. In one embodiment, the second heat treatment process may be performed under an argon atmosphere in a glove box.

[0122]

[0123] A solid electrolyte manufactured using the above-described manufacturing method can have a low impurity content and improved solvent stability. Accordingly, a solid electrolyte manufactured using the above-described manufacturing method can exhibit the following characteristics.

[0124] In one embodiment, when 0.2 g of the solid electrolyte according to the present invention is immersed in 3 g of a colorless and transparent non-polar solvent at room temperature and left for 10 days, when UV / Vis absorbance is measured in a wavelength range of 240 to 800 nm for the non-polar solvent, the height of the peak appearing in the wavelength range of 240 to 350 nm may be 1.0 or less with respect to the baseline. In the present specification, the baseline may mean a line drawn parallel to the x-axis based on the UV / Vis absorbance value at a wavelength of 740 nm. In one embodiment, when UV / Vis absorbance is measured under the above conditions, the height of the peak appearing in the wavelength range of 240 to 350 nm may be 1.0 or less or 0.8 or less with respect to the baseline.

[0125] The colorless, transparent, non-polar solvent may be, for example, a solvent selected from the group consisting of xylene, benzene, toluene, pentane, hexane, cyclohexane, and octyl acetate.

[0126] The UV / Vis spectral results above allow us to estimate the content of impurities in a solid electrolyte. For example, the content of impurities in a solid electrolyte can be estimated by immersing the solid electrolyte in a colorless, transparent, non-polar solvent, leaving it for a certain period of time, and then observing the color change in the non-polar solvent. Specifically, when left in the same solvent for the same period of time, the higher the content of impurities in the solid electrolyte, the darker the color of the solvent becomes. In other words, when the impurity content is low, the solvent becomes light in color, and when the impurity content is high, the solvent becomes dark in color. Therefore, the content of impurities can be estimated through the color change in the solvent.

[0127] The solid electrolyte according to embodiments of the present invention can have improved solvent stability by undergoing two heat treatment processes. Accordingly, when comparing before and after solvent immersion, the decrease in ionic conductivity of the solid electrolyte can be small, and the peak change in the X-ray photoelectron spectroscopy (XPS) graph for the solid electrolyte can be small.

[0128] In one embodiment, the solid electrolyte according to the present invention may have a ratio of the ionic conductivity of the solid electrolyte after immersion to the ionic conductivity of the solid electrolyte before immersion when 0.2 g of the solid electrolyte is immersed in 3 g of a colorless, transparent, non-polar solvent at room temperature and left for 10 days, which is 0.4 or more. For example, the ratio of the ionic conductivity of the solid electrolyte after immersion to the ionic conductivity of the solid electrolyte before immersion may be 0.4 to 0.9, 0.4 to 0.8, or 0.5 to 0.8.

[0129]

[0130] 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.

[0131]

[0132] Example: Preparation of solid electrolyte

[0133] Li2S powder, P2S5 powder, and LiCl powder were prepared as raw materials for a sulfide-based solid electrolyte in a stoichiometric ratio to have a composition of Li6PS5Cl. The raw materials and zirconia balls with a diameter of 5 mm were placed in a container with an internal volume of 70 ml, and mechanically milled for 24 hours at room temperature under an Ar atmosphere to form a mechanochemical reaction to form a mixture.

[0134] The above mixture was placed in a carbon crucible and subjected to a first heat treatment (sintering) process at 450°C to 550°C for 5 to 10 hours under an Ar atmosphere to manufacture a solid electrolyte precursor.

[0135] A solid electrolyte precursor and zirconia balls were placed in a xylene solvent and ball milled using a planetary mill. Ball milling was performed at 400 to 500 rpm for 3 to 5 hours. The powder obtained through milling was dried in a vacuum oven at 80°C for 2 hours.

[0136] The dried powder was subjected to a second heat treatment (post-heat treatment) process at a temperature of 200°C to 300°C for 4 to 5 hours in a glove box under an Ar atmosphere to manufacture a solid electrolyte.

[0137] The particle size of the manufactured sulfide-based solid electrolyte was 0.5 um to 2 um.

[0138]

[0139] Comparative Example 1

[0140] A solid electrolyte was manufactured in the same manner as in the example, except that the second heat treatment process was not performed.

[0141] The particle size of the manufactured sulfide-based solid electrolyte was 0.5 um to 2 um.

[0142]

[0143]

[0144] Comparative Example 2

[0145] A solid electrolyte was manufactured using the same method as in Comparative Example 1, except that wet milling was performed at 400 to 500 rpm for 2 hours.

[0146] The particle size of the manufactured sulfide-based solid electrolyte was 3 um to 5 um.

[0147]

[0148] Evaluation Example 1: UV / Vis Spectrum Evaluation

[0149] The solid electrolyte according to the examples and comparative examples was immersed in 0.2 g of 3 g of xylene solvent at 25°C and left for 10 days. Thereafter, the UV / Vis absorbance of the solvent in the wavelength range of 240 to 800 nm was measured.

[0150] The color change of the solvent after immersion was observed and shown in Figure 8 below, and the UV / Vis spectrum was shown in Figure 9 below.

[0151] Referring to Fig. 8, it can be confirmed that the color of the solution in which the solid electrolyte of the example was immersed is the lightest.

[0152] Referring to Figure 9, the solution in which the solid electrolyte of the example was immersed is S4 2- , S6 2- It can be confirmed that the UV-vis peak in the 240-350 nm region, known as ion, is significantly reduced.

[0153] Evaluation Example 2: Ionic Conductivity Evaluation

[0154] The ionic conductivity of the solid electrolytes manufactured according to the Examples and Comparative Examples was measured. 0.2 g of the solid electrolytes were immersed in 3 g of xylene solvent at 25°C, left for 10 days, and then the ionic conductivity was measured again. The results of the ionic conductivity measurements before and after immersion are shown in Figure 10 below.

[0155] Referring to Fig. 10, it can be confirmed that the solid electrolyte according to the embodiment exhibits a smaller decrease in ionic conductivity compared to the solid electrolyte according to the comparative examples. Specifically, it can be confirmed that the solid electrolyte according to the embodiment has a ratio of ionic conductivity after immersion to ionic conductivity before immersion of 0.5 or more. This may indicate that the solid electrolyte according to the embodiment has excellent solvent stability.

[0156]

[0157] Evaluation Example 3: X-ray photoelectron spectroscopy

[0158] X-ray photoelectron spectroscopy analysis was performed on the solid electrolytes manufactured according to the examples and comparative examples. 0.2 g of the solid electrolytes were immersed in 3 g of xylene solvent at 25°C, left for 10 days, and then XPS analysis was performed. XPS graphs before and after immersion are shown in Figure 11 below.

[0159] Referring to Figure 11, it can be confirmed that the solid electrolyte according to the example after immersion has smaller peaks related to impurities P2S5 and PO4 than the solid electrolyte according to the comparative example.

[0160]

[0161] Although the preferred embodiments of the present invention have been described above, the present invention is not limited thereto, and various modifications can be made within the scope of the patent claims, the detailed description of the invention, and the attached drawings, and it is obvious that this also falls within the scope of the present invention.

Claims

1. Forming a mixture by dry mixing sulfide-based solid electrolyte raw materials; Performing a first heat treatment process at a first temperature on the above mixture to form first particles; Injecting the first particle into a solvent and milling to form the second particle; Drying the second particles to form third particles; and Including performing a second heat treatment process at a second temperature on the third particle, A method for manufacturing a solid electrolyte, wherein the second temperature is lower than the first temperature.

2. In paragraph 1, A method for manufacturing a solid electrolyte wherein the second temperature is 200°C to 400°C.

3. In paragraph 1, A method for manufacturing a solid electrolyte, wherein the second heat treatment process is performed for 3 to 6 hours.

4. In paragraph 1, A method for manufacturing a solid electrolyte in which the above second heat treatment process is performed under an inert atmosphere.

5. In paragraph 1, A method for manufacturing a solid electrolyte, wherein the above sulfide-based solid electrolyte raw material includes Li2S, P2S5 and LiX, and wherein X is Cl, Br or I.

6. In paragraph 1, A method for manufacturing a solid electrolyte, wherein the above sulfide-based solid electrolyte raw material is provided in powder form.

7. In paragraph 1, A method for producing a solid electrolyte, wherein the solvent comprises at least one selected from the group consisting of xylene, benzene, toluene, octyl acetate, pentane, hexane, and cyclohexane.

8. In paragraph 1, The above dry mixing is a solid electrolyte manufacturing method including a ball milling process.

9. In paragraph 1, A method for manufacturing a solid electrolyte wherein the first temperature is 300°C to 600°C.

10. In paragraph 1, A method for manufacturing a solid electrolyte, wherein the first heat treatment process is performed for 5 to 10 hours.

11. In paragraph 1, The above solid electrolyte is a method for manufacturing a solid electrolyte having an argyrodite crystal structure.

12. In paragraph 1, The above solid electrolyte 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-x I x A method for manufacturing a solid electrolyte comprising at least one selected from the group consisting of (0≤x≤2).

13. Solid electrolyte manufactured by the method according to paragraph 1: When 0.2 g of the above solid electrolyte was immersed in 3 g of a colorless, transparent, non-polar solvent at 25°C and left for 10 days, When measuring UV / Vis absorbance in the wavelength range of 240 to 800 nm for the above nonpolar solvent, the height of the peak appearing in the wavelength range of 240 to 350 nm is 1.0 (au) or less.

14. In paragraph 13, A solid electrolyte having an average particle diameter of 0.5 μm to 5 μm.

15. In paragraph 13, A solid electrolyte having a ratio of the ionic conductivity of the solid electrolyte after immersion to the ionic conductivity of the solid electrolyte before immersion of 0.5 to 0.

8.

16. In paragraph 13, A solid electrolyte comprising at least one selected from the group consisting of the colorless and transparent non-polar xylene, benzene, toluene, octyl acetate, pentane, hexane, and cyclohexane.

17. In paragraph 13, The above solid electrolyte 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-x I x A solid electrolyte comprising at least one selected from the group consisting of (0≤x≤2).

18. Including anode, cathode, and solid electrolyte layer, The solid electrolyte layer is an all-solid-state battery comprising the solid electrolyte described in claim 13.

19. In paragraph 18, An all-solid-state battery wherein the cathode comprises at least one carbon selected from the group consisting of carbon black, acetylene black, furnace black, ketjen black, and graphene.

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