Solid electrolyte membrane and all-solid-state battery including the same

Abstract

The present invention provides a solid electrolyte membrane for an all-solid-state battery, comprising first solid electrolyte particles and second solid electrolyte particles, the Young's modulus of the first solid electrolyte particles is higher than the Young's modulus of the second solid electrolyte particles; the first solid electrolyte particles and the second solid electrolyte particles have an average particle size (D50) of 1 to 5 μm; The first solid electrolyte particles and the second solid electrolyte particles are mixed in a weight ratio of 7:3 to less than 2:8, and the present invention relates to a solid electrolyte membrane for an all-solid-state battery and an all-solid-state battery including the same.

Description

[Technical Field]

[0001] This application claims the benefit of priority based on Korean Patent Application No. 10-2023-0063088, filed May 16, 2023, and incorporates all of the contents disclosed in the documents of that Korean patent application as part of this specification.

[0002] The present invention relates to a solid electrolyte membrane and an all-solid-state battery including the same. [Background technology]

[0003] Currently, various batteries that can overcome the limitations of lithium secondary batteries are being researched from the viewpoints of battery capacity, safety, output, size increase, miniaturization, and the like.

[0004] Academia and industry are continuously researching metal-air batteries, which have a much larger theoretical capacity than lithium secondary batteries, all-solid-state batteries, which are safe and do not pose a risk of explosion, supercapacitors, NaS batteries or RFBs (redox flow batteries), which are large-scale batteries, and thin film batteries, which are ultra-miniaturized batteries.

[0005] All-solid-state batteries are batteries that replace the liquid electrolyte used in conventional lithium secondary batteries with a solid, and they can significantly improve safety by not using flammable solvents inside the battery and completely eliminating the risk of fire or explosion caused by the decomposition reaction of conventional electrolytes.In addition, because lithium (Li) metal or lithium alloys can be used as the anode material, they have the advantage of dramatically improving the energy density relative to the mass and volume of the battery.

[0006] All-solid-state batteries are manufactured by placing a solid electrolyte membrane between the positive electrode and the negative electrode and then pressing under high pressure. At this time, lithium ions (Li+ The smoother the movement of lithium ions, the better the performance of the all-solid-state battery. However, if the solid electrolyte membrane is too hard, there will be a large resistance to the movement of lithium ions at the interface between the positive electrode and the solid electrolyte membrane, and at the interface between the negative electrode and the solid electrolyte membrane, which may result in a decrease in the performance of the all-solid-state battery.

[0007] Therefore, research is needed to minimize the resistance generated at the interface between the positive electrode and the solid electrolyte membrane and the interface between the negative electrode and the solid electrolyte membrane, thereby improving the performance of all-solid-state batteries. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Korean Patent Publication No. 2021-0087919 Summary of the Invention [Problem to be solved by the invention]

[0009] The present inventors have found that when a solid electrolyte membrane includes first solid electrolyte particles and second solid electrolyte particles and the Young's modulus, average particle size, and weight ratio of the first solid electrolyte particles and the second solid electrolyte particles are adjusted, the adhesive strength at the interface between the positive electrode and the solid electrolyte membrane and the interface between the negative electrode and the solid electrolyte membrane can be improved and the resistance generated at the interface can be minimized, thereby completing the present invention.

[0010] Therefore, an object of the present invention is to provide a solid electrolyte membrane for an all-solid-state battery that can reduce the resistance generated at the interface between the positive electrode and the solid electrolyte membrane and at the interface between the negative electrode and the solid electrolyte membrane in the all-solid-state battery.

[0011] Another object of the present invention is to provide an all-solid-state battery that includes the solid electrolyte membrane and is thereby excellent in life characteristics and rate characteristics. [Means for solving the problem]

[0012] In order to achieve the above purpose, The present invention provides a solid electrolyte membrane for an all-solid-state battery, comprising first solid electrolyte particles and second solid electrolyte particles, the Young's modulus of the first solid electrolyte particles is higher than the Young's modulus of the second solid electrolyte particles; the first solid electrolyte particles and the second solid electrolyte particles have an average particle size (D50) of 1 to 5 μm; The present invention provides a solid electrolyte membrane for an all-solid-state battery, wherein the first solid electrolyte particles and the second solid electrolyte particles are mixed at a weight ratio of 7:3 to less than 2:8.

[0013] The present invention also provides an all-solid-state battery including a positive electrode, a negative electrode, and a solid electrolyte membrane interposed therebetween, The solid electrolyte membrane provides an all-solid-state battery, which is the solid electrolyte membrane of the present invention. [Effects of the Invention]

[0014] The solid electrolyte membrane for an all-solid-state battery of the present invention includes first and second solid electrolyte particles. By adjusting the Young's modulus, average particle size, and weight ratio of the first and second solid electrolyte particles, the adhesive strength at the interface between the positive electrode and the solid electrolyte membrane and the interface between the negative electrode and the solid electrolyte membrane can be improved, and resistance generated at the interface can be minimized.

[0015] Therefore, an all-solid-state battery including the solid electrolyte membrane of the present invention can have excellent effects in terms of life characteristics and rate characteristics. [Brief explanation of the drawings]

[0016] [Figure 1] 1 is a graph showing measurement results of life characteristics of Example 1, Comparative Example 1, and Comparative Example 2. [Figure 2] 10 is a graph showing the life characteristics measured in Comparative Example 4. [Figure 3] 1 is a graph showing rate characteristic measurements of Example 1, Comparative Example 2, and Comparative Example 3. DETAILED DESCRIPTION OF THE INVENTION

[0017] The present invention will now be described in more detail.

[0018] The terms and words used in this specification and claims should not be interpreted in a limited way to their ordinary or dictionary meanings, but should be interpreted in a way that is consistent with the technical idea of the present invention, based on the principle that the inventor can appropriately define the concept of the term in order to best describe his or her invention.

[0019] The terms used in the present invention are merely used to describe specific embodiments and are not intended to limit the present invention. A singular expression includes a plural expression unless the context clearly indicates otherwise. In the present invention, the terms "comprise" or "have" and the like are intended to specify the presence of features, numbers, steps, operations, components, parts, or combinations thereof described in the specification, and should be understood not to preclude the presence or possibility of addition of one or more other features, numbers, steps, operations, components, parts, or combinations thereof.

[0020] Solid electrolyte membrane for all-solid-state batteries The present invention relates to a solid electrolyte membrane for an all-solid-state battery, the solid electrolyte membrane includes first solid electrolyte particles and second solid electrolyte particles; the Young's modulus of the first solid electrolyte particles is higher than the Young's modulus of the second solid electrolyte particles; the first solid electrolyte particles and the second solid electrolyte particles have an average particle size (D50) of 1 to 5 μm; The first solid electrolyte particles and the second solid electrolyte particles may be mixed in a weight ratio of 7:3 to less than 2:8.

[0021] The solid electrolyte membrane for an all-solid-state battery of the present invention includes first and second solid electrolyte particles. The first and second solid electrolyte particles may have different Young's modulus, and the Young's modulus of the first solid electrolyte particles may be higher than that of the second solid electrolyte particles. By including different types of solid electrolyte particles with different Young's moduli, the Young's modulus of the solid electrolyte membrane can be adjusted. Therefore, the resistance generated at the interface between the positive electrode and the solid electrolyte membrane and the interface between the negative electrode and the solid electrolyte membrane of the all-solid-state battery can be reduced, thereby providing an all-solid-state battery with improved life and rate characteristics.

[0022] The first solid electrolyte particles may have a Young's modulus of 40 to 80 GPa, preferably 40 to 60 GPa, and most preferably 40 to 50 GPa. Generally, the higher the Young's modulus of a particle, the harder and less likely it is to break. When the first solid electrolyte particles have a Young's modulus within this range, the shape of the solid electrolyte membrane can be maintained even if volume changes occur during charge and discharge of the all-solid-state battery.

[0023] The second solid electrolyte particles may have a Young's modulus of 5 to 30 GPa, preferably 10 to 25 GPa, and most preferably 15 to 20 GPa. The second solid electrolyte particles having a Young's modulus within this range may facilitate deformation under high pressure, resulting in excellent bonding between the solid electrolyte membrane and the electrode. Furthermore, the second solid electrolyte particles are located between the first solid electrolyte particles, minimizing pores and facilitating lithium ion migration, thereby improving the interfacial bonding strength between the solid electrolyte membrane and the electrode.

[0024] The difference in Young's modulus between the first solid electrolyte particles and the second solid electrolyte particles may be 15 to 50 GPa, preferably 20 to 40 GPa. If the difference in Young's modulus is less than 15 GPa, the Young's modulus of the first solid electrolyte particles may be low or the Young's modulus of the second solid electrolyte particles may be high. If the Young's modulus of the first solid electrolyte particles is low and the difference in Young's modulus is less than 15 GPa, the physical rigidity of the solid electrolyte membrane may be reduced. If the Young's modulus of the second solid electrolyte particles is high, the effect of improving the interfacial bonding between the solid electrolyte membrane and the electrode may not be expected. Furthermore, if the Young's modulus exceeds 40 GPa, the Young's modulus of the first solid electrolyte particles may be high, reducing the interfacial bonding strength between the solid electrolyte membrane and the electrode, and reducing the interfacial resistance.

[0025] The first and second solid electrolyte particles may have the same average particle size (D50) of 1 to 5 μm, preferably 2 to 3 μm. If the average particle size (D50) of the first and second solid electrolyte particles is less than 1 μm, the first and second solid electrolyte particles may not be easily dispersed during the production of a solid electrolyte membrane, resulting in a solid electrolyte membrane with an uneven surface. This may result in a problem of reduced performance of an all-solid-state battery containing the first and second solid electrolyte particles. Furthermore, since the first and second solid electrolyte particles have an average particle size within this range, they are easily dispersed during the slurry process during the production process of the solid electrolyte membrane, resulting in a solid electrolyte membrane with a uniform surface.

[0026] The first solid electrolyte particles and the second solid electrolyte particles may be mixed in a weight ratio of 7:3 to less than 2:8, preferably 6:4 to 4:6, and most preferably 5:5. If the content of the first solid electrolyte particles exceeds this range, the Young's modulus of the solid electrolyte membrane may become excessively high, reducing the interfacial adhesion between the solid electrolyte membrane and the electrode, and the life characteristics of an all-solid-state battery including the same may be reduced. On the other hand, if the content of the first solid electrolyte particles is less than this range, the ionic conductivity of the solid electrolyte membrane may decrease, increasing its resistance, and the life characteristics and rate characteristics of an all-solid-state battery including the same may be reduced.

[0027] In the present invention, the Young's modulus of the solid electrolyte membrane may be 20 to 40 GPa, preferably 25 to 35 GPa. The solid electrolyte membrane of the present invention includes the first solid electrolyte particles and the second solid electrolyte particles. The Young's modulus of the first solid electrolyte particles is higher than that of the second solid electrolyte particles. The average particle size (D50) of the first solid electrolyte particles and the second solid electrolyte particles is 1 to 5 μm. The first solid electrolyte particles and the second solid electrolyte particles are mixed in a weight ratio of 7:3 to less than 2:8. The second solid electrolyte particles have a low Young's modulus and are brittle. The second solid electrolyte particles are located between the first solid electrolyte particles, minimizing the spaces, i.e., pores, formed between the first solid electrolyte particles. This improves the interfacial adhesion between the solid electrolyte membrane and the electrode and reduces resistance to lithium ion migration. That is, the interfacial resistance generated at the interface between the solid electrolyte membrane and the electrode can be reduced. This improves the life and rate characteristics of an all-solid-state battery including the solid electrolyte membrane.

[0028] Even if a solid electrolyte membrane containing one type of solid electrolyte has the same Young's modulus as that of the present invention, the space formed between the solid electrolyte particles cannot be minimized, and the effect of reducing the interfacial resistance cannot be obtained.

[0029] The first solid electrolyte particles and the second solid electrolyte particles may be one or more selected from the group consisting of a sulfide-based solid electrolyte, a polymer-based solid electrolyte, and an oxide-based solid electrolyte, and may preferably be a sulfide-based solid electrolyte.

[0030] The first solid electrolyte particles and the second solid electrolyte particles may be identical to each other, but differ only in Young's modulus.

[0031] The sulfide-based solid electrolyte contains sulfur (S) and has the ionic conductivity of a metal belonging to Group 1 or 2 of the periodic table, and may include Li-PS-based glass or Li-PS-based glass ceramic.

[0032] Specifically, the sulfide-based solid electrolyte may include one or more selected from the group consisting of Li6PS5Cl, Li6PS5Br, Li6PS5I, Li2S-P2S5, Li2S-LiI-P2S5, Li2S-LiI-Li2O-P2S5, Li2S-LiBr-P2S5, Li2S-Li2O-P2S5, Li2S-Li3PO4-P2S5, Li2S-P2S5-P2S5, Li2S-P2S5-SiS2, Li2S-P2S5-SnS, Li2S-P2S5-Al2S3, Li2S-GeS2, and Li2S-GeS2-ZnS, and preferably includes one or more selected from the group consisting of Li6PS5Cl, Li6PS5Br, and Li6PS5I. The Li6PS5Cl, Li6PS5Br, and Li6PS5I may be argyrodite-type solid electrolytes. The sulfide-based solid electrolyte may be doped with a trace element, for example, Li6PS5Cl further doped with bromine (Br).

[0033] The polymer solid electrolyte is a composite of lithium salt and polymer resin, i.e., a polymer electrolyte material formed by adding polymer resin to solvated lithium salt, and has a capacity of about 1x10 -7 S / cm or more, preferably about 1x10 -5 It can exhibit ionic conductivity of S / cm or more.

[0034] Non-limiting examples of the polymer resin include polyether polymers, polycarbonate polymers, acrylate polymers, polysiloxane polymers, phosphazene polymers, polyethylene derivatives, alkylene oxide derivatives such as polyethylene oxide, phosphate ester polymers, polyagitation lysine, polyester sulfide, polyvinyl alcohol, polyvinylidene fluoride, polymers containing ionic dissociation groups, etc., and the polymer electrolyte may include one or more of these. Examples of the polymer resin include branched copolymers in which amorphous polymers such as PMMA, polycarbonate, polysiloxane (pdms), and / or phosphazene are copolymerized with a comonomer on a polyethylene oxide (PEO) main chain, comb-like polymers, and crosslinked polymers, and the polymer electrolyte may include one or more of these.

[0035] In the polymer solid electrolyte, the lithium salt is an ionizable lithium salt, and Li + X - The anion of such a lithium salt is not particularly limited, but can be represented by F - , Cl - , Br - , I - , NO3 - , N(CN)2 - , BF4 - , ClO4 - , PF6 - , (CF3)2PF4 - , (CF3)3PF3 - , (CF3)4PF2 - , (CF3)5PF - , (CF3)6P - , CF3SO3 - , CF3CF2SO3 - , (CF3SO2)2N - , (FSO2)2N - , CF3CF2(CF3)2CO - , (CF3SO2)2CH - , (SF5)3C - , (CF3SO2)3C- , CF3(CF2)7SO3 - , CF3CO2 - , CH3CO2 - , SCN - , (CF3CF2SO2)2N - Examples include:

[0036] The oxide-based solid electrolyte may contain oxygen (O) and have the ionic conductivity of a metal belonging to Group 1 or Group 2 of the periodic table. For example, an LLTO-based compound, Li6La2CaTa2O 12 , Li6La2ANb2O 12 (A is Ca or Sr), Li2Nd3TeSbO 12 , Li3BO 2.5 N 0.5 , Li9SiAlO8, LAGP compounds, LATP compounds, Li1 +x Ti 2-x Al x Si y (PO4) 3-y (where 0≦x≦1, 0≦y≦1), LiAl x Zr 2-x (PO4)3 (where 0≦x≦1), LiTi x Zr 2-x The compound may contain one or more compounds selected from (PO4)3 (where 0≦x≦1), LISICON-based compounds, LIPON-based compounds, perovskite-based compounds, Nasicon-based compounds, and LLZO-based compounds.

[0037] The solid electrolyte membrane may further include a binder, and the type of the binder is not particularly limited as long as it is a binder commonly used in the art.

[0038] For example, acrylonitrile butadiene rubber (NBR), styrene butadiene rubber (SBR), butadiene rubber (BR), styrene-butadiene-styrene copolymer (SBS), polybutadiene (PAN), styrene-ethylene / butylene-styrene block copolymer (SEBS), silicone rubber (SR), hydrogenated nitrile butadiene rubber (HNBR), poly(ethylene vinyl acetate) (PEVA), poly(methyl methacrylate) (PMMA), polyisobutene (PIB), polyacrylate, etc. may be used, but are not limited to these.

[0039] The binder may be included in an amount of 0.5 to 5 wt % based on the total weight of the solid electrolyte membrane. The combined weight of the first and second solid electrolytes may be included in an amount of 95 to 99.5 wt % based on the total weight of the solid electrolyte membrane. By including the solid electrolytes and binders as described above, the amount of binder that acts as a resistance to ion conductivity can be minimized, and a solid electrolyte membrane for an all-solid-state battery that can be maintained in a film form can be manufactured.

[0040] The solid electrolyte membrane for an all-solid-state battery of the present invention may be prepared by dispersing the first and second solid electrolyte particles in a solvent to prepare a slurry, applying the slurry to one side of a release film, drying the slurry, and then removing the release film. The slurry may further include a binder.

[0041] The first solid electrolyte particles, the second solid electrolyte particles, and the binder are as described above.

[0042] The type of the solvent is not particularly limited as long as it can disperse the first solid electrolyte particles, the second solid electrolyte particles, and the binder. For example, xylene, hexane, benzene, anisole, isobutyl isobutyrate, toluene, butyl butyrate, etc. may be used.

[0043] The solid electrolyte membrane for an all-solid-state battery may have an ionic conductivity of 1 to 1.6 mS / cm. The ionic conductivity may be measured at room temperature (25° C.).

[0044] All solid state battery The present invention relates to an all-solid-state battery including a positive electrode, a negative electrode, and a solid electrolyte membrane interposed therebetween, and the solid electrolyte membrane may be the solid electrolyte membrane of the present invention described above.

[0045] The all-solid-state battery is a lithium secondary battery, and is not limited to a positive electrode or a negative electrode, and may be a lithium-air battery, a lithium oxide battery, a lithium-sulfur battery, or a lithium metal battery.

[0046] The positive electrode may include a positive electrode current collector and a positive electrode active material coated on one or both surfaces of the positive electrode current collector.

[0047] The positive electrode current collector is used to support the positive electrode active material and is not particularly limited as long as it has excellent conductivity and is electrochemically stable in the voltage range of a lithium secondary battery. For example, the positive electrode current collector may be made of any metal selected from the group consisting of copper, aluminum, stainless steel, titanium, silver, palladium, nickel, alloys thereof, and combinations thereof. The stainless steel may be surface-treated with carbon, nickel, titanium, or silver. The alloy may preferably be an aluminum-cadmium alloy. Alternatively, calcined carbon, a non-conductive polymer surface-treated with a conductive material, or a conductive polymer may be used.

[0048] The positive electrode current collector may have fine irregularities on its surface to strengthen the bonding force with the positive electrode active material, and may be in various forms such as a film, sheet, foil, mesh, net, porous material, foam, or nonwoven fabric.

[0049] The positive electrode active material may include a positive electrode active material, and optionally a conductive material and a binder.

[0050] The positive electrode active material may vary depending on the type of all-solid-state battery. For example, the positive electrode active material may be a layered compound such as lithium cobalt oxide (LiCoO2), lithium nickel oxide (LiNiO2), or a compound substituted with one or more transition metals; 1+x Mn 2-x O4 (0≦x≦0.33), lithium manganese oxides such as LiMnO3, LiMn2O3, and LiMnO2; lithium copper oxide (Li2CuO2); vanadium oxides such as LiV3O8, V2O5, and Cu2V2O7; chemical formula LiNi 1-x M x Ni-site lithium nickel oxide represented by the formula LiMnO2 (M=Co, Mn, Al, Cu, Fe, Mg, B, or Ga; 0.01≦x≦0.3) 2-x M x Lithium manganese composite oxides represented by O2 (M = Co, Ni, Fe, Cr, Zn, or Ta; 0.01 ≤ x ≤ 0.1) or Li2Mn3MO8 (M = Fe, Co, Ni, Cu, or Zn); LiNi x Mn 2-x Lithium manganese composite oxide with a spinel structure represented by O4; LiCoPO4; LiFePO4; elemental sulfur (S8); Li2S n (n=1), organic sulfur compounds or carbon-sulfur polymers (C2S x ) n The present invention is not limited to the above, but may include sulfur-based compounds such as: x=2.5 to 50, n=2).

[0051] The conductive material electrically connects the electrolyte and the positive electrode active material and serves as a path for electrons to move from a current collector to the positive electrode active material. Any conductive material may be used without limitation as long as it does not cause chemical changes in the lithium secondary battery and is porous and conductive.

[0052] For example, the conductive material may be a porous carbon-based material, such as carbon black, graphite, graphene, activated carbon, carbon fiber, metallic fiber such as metal mesh, metallic powder such as copper, silver, nickel, aluminum, or organic conductive material such as polyphenylene derivative. The conductive materials may be used alone or in combination.

[0053] Currently, commercially available conductive materials include acetylene black series (products of Chevron Chemical Company or Gulf Oil Company, etc.), Ketjen Black EC series (products of Armak Company), Vulcan XC-72 (products of Cabot Company), and Super P (products of MMM), etc. Examples include acetylene black, carbon black, and graphite.

[0054] In addition, the positive electrode may further include a binder. The binder enhances the binding strength between components constituting the positive electrode and between the components and the current collector. Any binder known in the art may be used.

[0055] For example, the binder may be one or a mixture or copolymer of two or more selected from the group consisting of: fluororesin-based binders including polyvinylidene fluoride (PVdF) or polytetrafluoroethylene (PTFE); rubber-based binders including styrene butadiene rubber (SBR), acrylonitrile-butadiene rubber, and styrene-isoprene rubber; cellulose-based binders including carboxyl methyl cellulose (CMC), starch, hydroxypropyl cellulose, and regenerated cellulose; polyalcohol-based binders; polyolefin-based binders including polyethylene and polypropylene; polyimide-based binders; polyester-based binders; and silane-based binders.

[0056] The negative electrode may include a negative electrode current collector and a negative electrode active material disposed on the negative electrode current collector. Similarly to the positive electrode, the negative electrode may include a conductive material and a binder, as needed. The negative electrode current collector, conductive material, and binder are as described above.

[0057] The negative electrode active material is a lithium ion (Li + Any material that can reversibly intercalate or deintercalate lithium ions, or that can react with lithium ions to reversibly form a lithium-containing compound, is possible.

[0058] For example, the negative electrode active material may be one or more carbon-based materials selected from the group consisting of crystalline artificial graphite, crystalline natural graphite, amorphous hard carbon, low-crystalline soft carbon, carbon black, acetylene black, Ketjen black, Super-P, graphene, and fibrous carbon; Si-based materials; Li x Fe2O3(0≦x≦1), Li x WO2(0≦x≦1), Sn x Me 1-xMe y O z (Me: Mn, Fe, Pb, Ge; Me': Al, B, P, Si, Group 1, 2, 3 elements of the periodic table, halogen; 0 < x ≤ 1; 1 ≤ y ≤ 3; 1 ≤ z ≤ 8) and other metal composite oxides; lithium metal; lithium alloys; silicon-based alloys; tin-based alloys; metal oxides such as SnO, SnO2, PbO, PbO2, Pb2O3, Pb3O4, Sb2O3, Sb2O4, Sb2O5, GeO, GeO2, Bi2O3, Bi2O4, Bi2O5; conductive polymers such as polyacetylene; Li-Co-Ni-based materials; titanium oxides; lithium titanium oxides, etc. may be included, but are not limited thereto.

[0059] Further, the negative electrode may include a negative electrode current collector and a coating layer including metal-carbon composite particles located on the negative electrode current collector. This may mean an anodeless negative electrode that does not contain a negative electrode active material.

[0060] During charging of the all-solid-state battery, lithium ions may pass through the coating layer and reach the surface of the negative electrode current collector, and these may be electrodeposited to form a lithium metal layer.

[0061] The metal-carbon composite particles may have a form in which carbon particles and metal particles are adhered to each other or one of them is coated on the surface of the other, and may be physically or chemically bonded.

[0062] The carbon particles may include natural graphite, artificial graphite, hard carbon, soft carbon, carbon black, acetylene black, ketjen black, channel black, furnace black, lamp black, summer black, carbon nanotubes, fullerenes, carbon fibers, fluorinated carbon.

[0063] The metal particles are lithiophilic metals, such as Ni, Cu, Ag, Au, Pt, Al, Zn, and Bi, and may be one or a combination of two or more of these. The incorporation of the lithiophilic metal is advantageous for forming a stable and uniform lithium layer on the surface of the current collector.

[0064] The negative electrode may be manufactured by mixing a binder solution and the composite particles to prepare a slurry for forming a coating layer, and then coating and drying the slurry on a negative electrode current collector. In this case, the binder may be a conventional binder used in the art.

[0065] The method for producing the all-solid-state battery is not particularly limited in the present invention, and known methods can be used.

[0066] For example, a solid electrolyte membrane is placed between a positive electrode and a negative electrode, and then the membrane is compression-molded to assemble a cell. The assembled cell is placed in an exterior packaging and then sealed by heat compression or the like. Examples of the exterior packaging include laminate packs made of aluminum, stainless steel, etc., and cylindrical or rectangular metal containers.

[0067] For example, the positive and negative electrodes are manufactured by a slurry coating process in which a slurry composition containing the respective electrode active materials, a solvent, and a binder is prepared, coated, and then dried.

[0068] The electrode slurry can be coated on the current collector by distributing the electrode slurry on the current collector and then uniformly dispersing it using a doctor blade, die casting, comma coating, screen printing, etc. Alternatively, the electrode slurry can be formed on a separate substrate and then bonded to the current collector by pressing or lamination. In this case, the final coating thickness can be adjusted by adjusting the concentration of the slurry solution or the number of coatings.

[0069] The drying step is a process of removing the solvent and water from the slurry in order to dry the slurry coated on the metal current collector, and may vary depending on the solvent used. For example, it is performed in a vacuum oven at 50 to 200°C. Examples of drying methods include drying with warm air, hot air, or low-humidity air, vacuum drying, and drying by irradiation with (far) infrared rays or electron beams. The drying time is not particularly limited, but is usually within a range of 30 seconds to 24 hours.

[0070] After the drying process, a cooling process may be further included, and the cooling process may be slow cooling to room temperature so that the recrystallization structure of the binder is well formed.

[0071] In addition, if necessary, after the drying process, a rolling process may be performed in which the electrode is passed between two rolls heated to a high temperature and compressed to a desired thickness in order to increase the capacity density of the electrode and the adhesion between the current collector and the active material. The rolling process is not particularly limited in the present invention, and known pressing processes can be used. For example, the electrode may be passed between rotating rolls or may be pressed using a flat press.

[0072] The shape of the all-solid-state battery is not particularly limited, and it can be in various shapes such as a cylindrical shape, a laminated shape, a coin shape, or the like.

[0073] Preferred examples will be described below to aid in understanding the present invention. However, the following examples are merely illustrative of the present invention, and it will be apparent to those skilled in the art that various changes and modifications are possible within the scope of the scope and technical idea of the present invention. Naturally, such changes and modifications also fall within the scope of the appended claims.

[0074] <All-solid-state battery manufacturing> Example 1 Argyrodite (Li6PS5Cl) with a Young's modulus of 42 GPa and an average particle size (D50) of 2.5 μm was used as the first solid electrolyte particles. Argyrodite (Li6PS5Cl) with a Young's modulus of 18 GPa and an average particle size (D50) of 2.5 μm was used as the second solid electrolyte particles. Butadiene rubber was used as the binder.

[0075] The first solid electrolyte particles, the second solid electrolyte particles, and a binder were added to a butyl butyrate solvent to prepare a slurry, where the weight ratio of the first solid electrolyte particles to the second solid electrolyte particles was 5:5, and the weight ratio of the first solid electrolyte particles to the second solid electrolyte particles to the binder was 49:49:2.

[0076] The release film was polyethylene terephthalate, and the slurry was coated onto the release film using a bar coater. The film was then dried at room temperature for 5 hours, and the release film was removed to prepare a solid electrolyte membrane for an all-solid-state battery. The Young's modulus of the solid electrolyte membrane for an all-solid-state battery was 30 GPa.

[0077] A cathode active material (NCM 811), a conductive material (carbon fiber), a solid electrolyte (Li6PS5Cl), and a binder (polytetrafluoroethylene) were mixed in a weight ratio of 84:0.2:14.8:1, and the mixture was applied to a cathode current collector and then rolled to prepare a cathode.

[0078] A mixture of a negative electrode active material (carbon black) and a binder (polyvinylidene fluoride) was coated to a thickness of 150 μm on a 10 μm thick SUS negative electrode current collector to prepare a negative electrode.

[0079] The solid electrolyte membrane was interposed between the positive electrode and the negative electrode to produce an all-solid-state battery, and a driving pressure of 10 MPa was applied using a jig.

[0080] Comparative Example 1 An all-solid-state battery was manufactured in the same manner as in Example 1, except that argyrodite (Li6PS5Cl) having a Young's modulus of 42 GPa and an average particle size (D50) of 2.5 μm was used as the first solid electrolyte particles, no second solid electrolyte was used, and the first solid electrolyte particles were used in an amount twice that of Example 1. The Young's modulus of the solid electrolyte membrane for the all-solid-state battery was 42 GPa.

[0081] Comparative Example 2 An all-solid-state battery was manufactured in the same manner as in Example 1, except that argyrodite (Li6PS5Cl) having a Young's modulus of 18 GPa and an average particle size (D50) of 2.5 μm was used as the second solid electrolyte particles, no first solid electrolyte particles were used, and the second solid electrolyte particles were used in an amount twice that of Example 1. The Young's modulus of the solid electrolyte membrane for the all-solid-state battery was 18 GPa.

[0082] Comparative Example 3. An all-solid-state battery was manufactured in the same manner as in Example 1, except that the first solid electrolyte particles and the second solid electrolyte particles were mixed in a weight ratio of 2:8.

[0083] Comparative Example 4. An all-solid-state battery was manufactured in the same manner as in Example 1, except that argyrodite (Li6PS5Cl) with an average particle size (D50) of 0.6 μm was used as the second solid electrolyte particles.

[0084] Experimental example 1. Measurement of life characteristics of all-solid-state batteries The life characteristics of the all-solid-state batteries of Example 1, Comparative Example 1, Comparative Example 2, and Comparative Example 4 were measured.

[0085] The life characteristics were measured by charging the all-solid-state batteries of Example 1, Comparative Example 1, Comparative Example 2, and Comparative Example 4 in CCCV mode at a temperature of 60° C. at 0.33 C up to 4.25 V, discharging at a constant current down to 3.0 V, and measuring the capacity retention rate after 100 charge-discharge cycles.

[0086] The results of Example 1, Comparative Example 1 and Comparative Example 2 are shown in FIG.

[0087] In the results shown in FIG. 1, the life characteristics of Example 1, which is an all-solid-state battery including the solid electrolyte membrane of the present invention, were measured to be the most excellent.

[0088] Comparative Example 1 contained only argyrodite (Li6PS5Cl) solid electrolyte particles with a Young's modulus of 42 GPa and an average particle size (D50) of 2.5 μm, and did not contain second solid electrolyte particles. Comparative Example 1 showed very low interfacial adhesion between the solid electrolyte film and the positive electrode and between the solid electrolyte film and the negative electrode, resulting in a deterioration in the life characteristics of the all-solid-state battery.

[0089] Comparative Example 2 contained only argyrodite (Li6PS5Cl) having a Young's modulus of 18 GPa and an average particle size (D50) of 2.5 μm as solid electrolyte particles, and did not contain first solid electrolyte particles. Comparative Example 2 showed that the resistance of the all-solid-state battery increased due to the low ionic conductivity of the solid electrolyte membrane, resulting in a deterioration in the life characteristics of the all-solid-state battery.

[0090] The results of Comparative Example 4 are shown in FIG.

[0091] In Comparative Example 4, argyrodite (Li6PS5Cl) with an average particle size (D50) of 0.6 μm was used as the second solid electrolyte particles, and the second solid electrolyte particles were not easily dispersed during the preparation of the solid electrolyte membrane, resulting in a non-uniform solid electrolyte membrane, which resulted in very poor life characteristics of the all-solid-state battery.

[0092] Experimental example 2: Measurement of rate characteristics of all-solid-state batteries The rate characteristics of the all-solid-state batteries of Example 1, Comparative Example 2, and Comparative Example 3 were measured.

[0093] The rate characteristics were measured by charging at 0.1C from 3.0 to 4.25V and discharging at 0.1, 0.33, 0.5 and 1C.

[0094] The results of Example 1, Comparative Example 2 and Comparative Example 3 are shown in FIG.

[0095] In the results shown in FIG. 3, Example 1, which is an all-solid-state battery including the solid electrolyte membrane of the present invention, exhibited excellent rate characteristics.

[0096] Comparative Example 2 contained only argyrodite (Li6PS5Cl) having a Young's modulus of 18 GPa and an average particle size (D50) of 2.5 μm as the solid electrolyte, and did not contain first solid electrolyte particles. In Comparative Example 2, the ionic conductivity of the solid electrolyte membrane was low, which increased the resistance of the all-solid-state battery, resulting in poor rate characteristics of the all-solid-state battery.

[0097] In Comparative Example 3, the first solid electrolyte particles and the second solid electrolyte particles were mixed at a weight ratio of 2:8, and the rate characteristics were improved compared to Comparative Example 2, but the rate characteristics were not as good as those of Example 1.

[0098] This results in a solid electrolyte mixture containing first and second solid electrolyte particles, the Young's modulus of the first solid electrolyte particles is higher than the Young's modulus of the second solid electrolyte particles; the first solid electrolyte particles and the second solid electrolyte particles have an average particle size (D50) of 1 to 5 μm; It has been confirmed that an all-solid-state battery including a solid electrolyte membrane for an all-solid-state battery in which the first solid electrolyte particles and the second solid electrolyte particles are mixed in a weight ratio of 7:3 to less than 2:8 has excellent effects on life characteristics and rate characteristics.

[0099] This is an effect exhibited by the solid electrolyte membrane minimizing the resistance generated at the interface between the positive electrode and the solid electrolyte membrane and at the interface between the negative electrode and the solid electrolyte membrane.

Claims

1. a solid electrolyte membrane for an all-solid-state battery, the solid electrolyte membrane comprising first solid electrolyte particles and second solid electrolyte particles; the Young's modulus of the first solid electrolyte particles is higher than the Young's modulus of the second solid electrolyte particles; the first solid electrolyte particles and the second solid electrolyte particles have an average particle size (D50) of 1 μm or more and 5 μm or less; The solid electrolyte membrane for an all-solid-state battery, wherein the first solid electrolyte particles and the second solid electrolyte particles are mixed in a weight ratio of 7:3 to less than 2:

8.

2. The solid electrolyte membrane according to claim 1 , wherein the first solid electrolyte particles have a Young's modulus of 40 GPa or more and 80 GPa or less.

3. The solid electrolyte membrane according to claim 1 , wherein the second solid electrolyte particles have a Young's modulus of 5 GPa or more and 30 GPa or less.

4. 2. The solid electrolyte membrane according to claim 1, wherein a difference in Young's modulus between the first solid electrolyte particles and the second solid electrolyte particles is 15 GPa or more and 50 GPa or less.

5. 2. The solid electrolyte membrane according to claim 1, wherein the particle size (D50) of the first solid electrolyte particles and the second solid electrolyte particles is 2 μm or more and 3 μm or less.

6. 2. The solid electrolyte membrane according to claim 1, wherein the first solid electrolyte particles and the second solid electrolyte particles are mixed in a weight ratio of 6:4 to 4:

6.

7. 2. The solid electrolyte membrane according to claim 1, wherein the first solid electrolyte particles and the second solid electrolyte particles contain at least one selected from the group consisting of a sulfide-based solid electrolyte, a polymer-based solid electrolyte, and an oxide-based solid electrolyte.

8. The solid electrolyte membrane according to claim 7 , wherein the first solid electrolyte particles and the second solid electrolyte particles are sulfide-based solid electrolytes.

9. The solid electrolyte membrane according to claim 1 , further comprising a binder.

10. 10. The solid electrolyte membrane according to claim 9, wherein the binder is contained in an amount of 0.5 wt % or more and 5 wt % or less with respect to the total weight of the solid electrolyte membrane.

11. An all-solid-state battery including a positive electrode, a negative electrode, and a solid electrolyte membrane interposed therebetween, The solid electrolyte membrane according to any one of claims 1 to 9, wherein the solid electrolyte membrane is an all-solid-state battery.

12. the negative electrode includes a negative electrode current collector and a negative electrode active material located on the negative electrode current collector; or The all-solid-state battery according to claim 11, comprising a negative electrode current collector and a coating layer containing metal-carbon composite particles located on the negative electrode current collector.

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