Solid electrolyte composition, solid electrolyte membrane containing the same, and all-solid-state battery

Abstract

The present invention includes a solid electrolyte, a binder, a solvent, and a dispersant, The present invention relates to a solid electrolyte composition for an all-solid-state battery, wherein the dispersant is a carboxylic acid compound having a weight-average molecular weight of 1,000 to 5,000, a solid electrolyte membrane produced from the composition, and an all-solid-state battery including the composition.

Description

[Technical Field]

[0001] This application claims the benefit of priority based on Korean Patent Application No. 10-2023-0078642, filed on June 20, 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 composition, a solid electrolyte membrane containing the same, and an all-solid-state battery. [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] To improve the energy density of all-solid-state batteries, it is essential to prepare a solid electrolyte membrane. The solid electrolyte membrane can be prepared by dispersing a solid electrolyte in a solvent to prepare a slurry-like solid electrolyte composition, applying the solid electrolyte composition to one side of a release film, drying the composition, and then removing the release film. To obtain a solid electrolyte membrane with a uniform thickness, it is very important to improve the dispersibility of the solid electrolyte within the solid electrolyte composition, which is closely related to the performance of the all-solid-state battery. If the solid electrolyte is not sufficiently dispersed within the solid electrolyte composition, the thickness of the solid electrolyte membrane may become less uniform, which may result in a problem of degraded performance of the all-solid-state battery.

[0007] Therefore, there is a need to study solid electrolyte compositions for all-solid-state batteries that can improve the dispersibility of solid electrolytes. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Korean Patent Publication No. 2021-0134748 Summary of the Invention [Problem to be solved by the invention]

[0009] In order to solve the above problems, the present inventors have conducted extensive research and found that the use of a carboxylic acid compound having a weight-average molecular weight of 1000 to 5000 as a dispersant in a solid electrolyte composition for an all-solid-state battery can suppress the aggregation phenomenon of the solid electrolyte in the composition and improve dispersibility, thereby completing the present invention.

[0010] Therefore, an object of the present invention is to provide a solid electrolyte composition for an all-solid-state battery that can improve the dispersibility of a solid electrolyte.

[0011] Another object of the present invention is to provide a solid electrolyte membrane having a uniform thickness and high ionic conductivity by producing the solid electrolyte membrane from the solid electrolyte composition.

[0012] Another object of the present invention is to provide an all-solid-state battery that includes the solid electrolyte membrane and has excellent life characteristics. [Means for solving the problem]

[0013] In order to achieve the above purpose, The present invention includes a solid electrolyte, a binder, and a dispersant, The solid electrolyte composition for an all-solid-state battery is provided, wherein the dispersant is a carboxylic acid compound having a weight-average molecular weight of 1,000 to 5,000.

[0014] The present invention also provides a solid electrolyte membrane for an all-solid-state battery produced using the solid electrolyte composition for an all-solid-state battery of the present invention.

[0015] 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]

[0016] The solid electrolyte composition for an all-solid-state battery of the present invention can have the effect of suppressing the phenomenon of aggregation of the solid electrolyte within the composition and improving dispersibility.

[0017] In addition, the solid electrolyte membrane manufactured using the solid electrolyte composition for an all-solid-state battery of the present invention has the effects of being uniform in thickness and having high ionic conductivity.

[0018] Furthermore, an all-solid-state battery including the solid electrolyte membrane of the present invention can have excellent performance. [Brief explanation of the drawings]

[0019] [Figure 1]1 is a graph showing the dispersed particle size distribution of solid electrolyte in a solid electrolyte composition for an all-solid-state battery in Experimental Example 1. [Figure 2] 10 is a graph showing the life characteristics of the all-solid-state battery of Experimental Example 3. DETAILED DESCRIPTION OF THE INVENTION

[0020] The present invention will now be described in more detail.

[0021] 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.

[0022] 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.

[0023] Solid electrolyte composition for all solid-state batteries The present invention relates to a solid electrolyte composition for an all-solid-state battery, The solid electrolyte composition for an all-solid-state battery includes a solid electrolyte, a binder, and a dispersant, The dispersant may be a carboxylic acid compound having a weight average molecular weight (Mw) of 1,000 to 5,000.

[0024] Conventional solid electrolyte compositions for all-solid-state batteries do not contain a dispersant, which causes aggregation of the solid electrolyte within the composition. This aggregation increases the particle size of the dispersed solid electrolyte within the solid electrolyte composition for all-solid-state batteries. This increase in particle size of the dispersed solid electrolyte results in an uneven thickness of the solid electrolyte membrane for all-solid-state batteries fabricated using the solid electrolyte composition, which can lead to a problem of reduced performance of the all-solid-state battery.

[0025] The solid electrolyte composition for an all-solid-state battery of the present invention uses a carboxylic acid compound having a weight-average molecular weight of 1,000 to 5,000 as a dispersant, thereby suppressing the aggregation of the solid electrolyte in the composition, improving the dispersibility of the solid electrolyte, and achieving excellent solubility in a solvent, thereby providing a solid electrolyte membrane for an all-solid-state battery having a uniform thickness and excellent ionic conductivity.

[0026] If the carboxylic acid compound is not used, the dispersibility of the solid electrolyte may be reduced. Therefore, it is preferable to use a carboxylic acid compound as a dispersant to improve the dispersibility of the solid electrolyte. Furthermore, if the weight-average molecular weight of the carboxylic acid compound is less than 1,000, the solubility in the solvent may be excellent, but the ability to control the aggregation of the solid electrolyte may be poor, which may cause the solid electrolyte to aggregate. Conversely, if the weight-average molecular weight of the carboxylic acid compound exceeds 5,000, the ability to control the aggregation of the solid electrolyte may be excellent, but the solubility in the solvent may be poor. This may result in a solid electrolyte membrane for an all-solid-state battery having an uneven thickness, which may degrade the performance of the all-solid-state battery including the solid electrolyte membrane.

[0027] The dispersing agent may include one or more selected from the group consisting of glycolic acid ethoxylate lauryl ether, glycolic acid ethoxylate oleyl ether, and glycolic acid ethoxylate 4-tert-butylphenyl ether.

[0028] The dispersant may be contained in an amount of 0.1 to 2 wt %, preferably 0.1 to 0.7 wt %, based on the total weight of the solid electrolyte composition for an all-solid-state battery. Dispersibility of the solid electrolyte can be improved within this range. If the dispersant is contained in an amount less than 0.1 wt %, the effect of improving the dispersibility of the solid electrolyte cannot be expected. If the dispersant is contained in an amount exceeding 2 wt %, the content of the solid electrolyte decreases, which may result in a problem of reduced performance of the all-solid-state battery.

[0029] The solid electrolyte composition for an all-solid-state battery of the present invention contains the above-mentioned dispersant, which improves the dispersibility of the solid electrolyte in the solid electrolyte composition and suppresses the aggregation phenomenon, so that the solid electrolyte in the solid electrolyte composition for an all-solid-state battery can exist without aggregation.

[0030] The particle size D50 of the solid electrolyte may be 0.5 to 1.5 μm and the particle size D99 may be 3 to 5 μm, and preferably the particle size D50 may be 0.6 to 1.1 μm and the particle size D99 may be 3 to 4 μm.

[0031] The dispersed particle size D50 of the solid electrolyte in the solid electrolyte composition for an all-solid-state battery may be 0.5 to 1.5 μm, and the dispersed particle size D99 may be 3 to 5 μm. More specifically, when a solid electrolyte having a particle size D50 of 0.5 to 1.5 μm and a particle size D99 of 3 to 5 μm is used as the solid electrolyte composition for an all-solid-state battery, the dispersed particle size D50 of the solid electrolyte in the solid electrolyte composition for an all-solid-state battery may be 0.5 to 1.5 μm, and the dispersed particle size D99 may be 3 to 5 μm. That is, the particle size of the solid electrolyte before dispersion and the dispersed particle size of the solid electrolyte after dispersion may be the same. Therefore, the solid electrolyte does not aggregate in the solid electrolyte composition for an all-solid-state battery, and can exist in a dispersed form.

[0032] In this specification, the dispersed particle size may refer to the particle size of the solid electrolyte dispersed in the solid electrolyte composition for an all-solid-state battery.

[0033] When the solid electrolyte composition for an all-solid-state battery does not contain a dispersant or when the weight-average molecular weight of the carboxylic acid compound serving as the dispersant is less than 1000 or more than 5000, the dispersion particle size D99 of the solid electrolyte in the solid electrolyte composition for an all-solid-state battery may exceed 5 μm for a solid electrolyte having a particle size D99 of 3 to 5 μm. This means that the effect of improving the dispersibility of the solid electrolyte cannot be achieved, and the solid electrolyte may aggregate. However, when a carboxylic acid compound having a weight-average molecular weight of 1000 to 5000 is contained as a dispersant, the particle size of the solid electrolyte and the dispersion particle size of the solid electrolyte in the solid electrolyte composition for an all-solid-state battery may be the same. In other words, the solid electrolyte composition for an all-solid-state battery of the present invention, by including the dispersant, can suppress the aggregation of the solid electrolyte in the solid electrolyte composition for an all-solid-state battery and improve dispersibility. In other words, the solid electrolyte is well dispersed in the solid electrolyte composition for an all-solid-state battery without aggregation, and the particle size can be maintained. Therefore, the particle size of the solid electrolyte and the dispersion particle size may be the same or similar in range.

[0034] Therefore, the ratio of the dispersed particle size (D99) / dispersed particle size (D50) of the solid electrolyte in the solid electrolyte composition for an all-solid-state battery may be 2-7, and preferably 3-6.

[0035] The solid electrolyte may include 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 preferably includes a sulfide-based solid electrolyte.

[0036] 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.

[0037] 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).

[0038] 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 -5It can exhibit ionic conductivity of S / cm or more.

[0039] 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.

[0040] 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:

[0041] 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, Li 1+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, 0≦y≦1), LiTi x Zr 2-x The material may contain one or more compounds selected from (PO4)3 (where 0≦x≦1, 0≦y≦1), LISICON-based compounds, LIPON-based compounds, perovskite-based compounds, Nasicon-based compounds, and LLZO-based compounds.

[0042] The solid electrolyte may be contained in an amount of 95 to 99% by weight based on the total weight of the solid electrolyte composition for an all-solid-state battery.

[0043] The binder is not particularly limited in type as long as it is one that is commonly used in the art.

[0044] 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. In the present invention, it may be preferable to use a styrene-butadiene-styrene copolymer.

[0045] The binder may be contained in an amount of 0.5 to 5% by weight based on the total weight of the solid electrolyte composition for an all-solid-state battery.

[0046] The solid electrolyte composition for an all-solid-state battery of the present invention may be in the form of a slurry in which a solid electrolyte, a binder, and a dispersant are dispersed in a solvent.

[0047] The type of the solvent is not particularly limited as long as it can disperse the solid electrolyte, binder, and dispersant. For example, xylene, hexane, benzene, anisole, isobutyl isobutyrate, toluene, butyl butyrate, etc. may be used.

[0048] Solid electrolyte membrane for all-solid-state batteries The present invention also relates to a solid electrolyte membrane for an all-solid-state battery produced using the solid electrolyte composition for an all-solid-state battery of the present invention.

[0049] The solid electrolyte membrane for an all-solid-state battery can be produced by applying the solid electrolyte composition for an all-solid-state battery to one surface of a release film, drying the applied composition, and then removing the release film.

[0050] The solid electrolyte composition for an all-solid-state battery exhibits excellent dispersibility, with the solid electrolyte not agglomerating within the composition. Therefore, when a solid electrolyte membrane for an all-solid-state battery is produced using the solid electrolyte composition for an all-solid-state battery, a solid electrolyte membrane for an all-solid-state battery having a uniform thickness and excellent ionic conductivity can be produced. In the present invention, the thickness of the solid electrolyte membrane for an all-solid-state battery may be 20 to 50 μm. Furthermore, the ionic conductivity of the solid electrolyte membrane for an all-solid-state battery is 1.3×10 -3 The ionic conductivity may be measured at room temperature (25° C.).

[0051] All solid state battery The present invention also 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 for an all-solid-state battery of the present invention described above.

[0052] 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.

[0053] The positive electrode may include a positive electrode current collector and a positive electrode active material layer coated on one or both surfaces of the positive electrode current collector.

[0054] The positive electrode current collector is used to support the positive electrode active material layer 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.

[0055] 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.

[0056] The positive electrode active material layer may include a positive electrode active material, and optionally a conductive material and a binder.

[0057] 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).

[0058] 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.

[0059] 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.

[0060] 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.

[0061] The binder enhances the binding strength between the components constituting the positive electrode and between these components and the current collector, and any binder known in the industry can be used.

[0062] 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.

[0063] The negative electrode may include a negative electrode current collector and a negative electrode active material layer disposed on the negative electrode current collector. Similarly to the positive electrode, the negative electrode may include a conductive material and a binder, if necessary. The negative electrode current collector, conductive material, and binder are as described above.

[0064] 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.

[0065] 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, Group 2, Group 3 elements of the periodic table, halogen; 0 < x ≤ 1; 1 ≤ y ≤ 3; 1 ≤ z ≤ 8) and other metal composite oxides; lithium metal; lithium alloy; silicon-based alloy; tin-based alloy; 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.

[0066] Also, 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.

[0067] 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.

[0068] 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.

[0069] 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, and fluorinated carbon.

[0070] 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.

[0071] 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.

[0072] The method for producing the all-solid-state battery is not particularly limited in the present invention, and known methods can be used.

[0073] 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.

[0074] 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.

[0075] 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.

[0076] 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.

[0077] 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.

[0078] 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.

[0079] 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.

[0080] 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.

[0081] Example 1 Example 1-1. Preparation of solid electrolyte composition for all-solid-state battery Argyrodite (Li6PS5Cl) having a particle size (D50) of 0.6 to 0.8 μm and a particle size (D99) of 3 to 4 μm as the solid electrolyte, styrene-butadiene-styrene copolymer as the binder, and glycolic acid ethoxylate lauryl ether having a weight average molecular weight of 4080 as the dispersant were mixed in a weight ratio of 98:1.7:0.3, and the mixture was added to isobutyl isobutylate to prepare a slurry-type solid electrolyte composition for an all-solid-state battery of Example 1-1.

[0082] Example 1-2. Production of solid electrolyte membrane for all-solid-state battery A polyethylene terephthalate release film was used, and the solid electrolyte composition for an all-solid-state battery prepared in Example 1-1 was applied to the release film using a bar coater. The film was then dried in a vacuum for 5 hours, and the release film was removed to prepare a solid electrolyte membrane for an all-solid-state battery of Example 1-2.

[0083] Examples 1-3. 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.

[0084] A mixture of a negative electrode active material (carbon black) and a binder (polyvinylidene fluoride) was coated to a thickness of 20 μm on a 10 μm thick SUS negative electrode current collector to prepare a negative electrode.

[0085] The solid electrolyte membrane prepared in Example 1-2 was interposed between the positive electrode and the negative electrode to prepare an all-solid-state battery of Example 1-3.

[0086] Example 2. A solid electrolyte composition for an all-solid-state battery of Example 2-1, a solid electrolyte membrane for an all-solid-state battery of Example 2-2, and an all-solid-state battery of Example 2-3 were manufactured in the same manner as in Examples 1-1, 1-2, and 1-3, except that glycolic acid ethoxylate oleyl ether having a weight average molecular weight of 2220 was used as a dispersant.

[0087] Example 3. A solid electrolyte composition for an all-solid-state battery of Example 3-1, a solid electrolyte membrane for an all-solid-state battery of Example 3-2, and an all-solid-state battery of Example 3-3 were produced in the same manner as in Examples 1-1, 1-2, and 1-3, except that glycolic acid ethoxylate 4-tert-butylphenyl ether having a weight average molecular weight of 1080 was used as a dispersant.

[0088] Comparative Example 1 A solid electrolyte composition for an all-solid-state battery of Comparative Example 1-1, a solid electrolyte membrane for an all-solid-state battery of Comparative Example 1-2, and an all-solid-state battery of Comparative Example 1-3 were produced in the same manner as in Examples 1-1, 1-2, and 1-3, except that a dispersant was not used.

[0089] Comparative Example 2 A solid electrolyte composition for an all-solid-state battery of Comparative Example 2-1, a solid electrolyte membrane for an all-solid-state battery of Comparative Example 2-2, and an all-solid-state battery of Comparative Example 2-3 were manufactured in the same manner as in Examples 1-1, 1-2, and 1-3, except that glycolic acid ethoxylate lauryl ether having a weight average molecular weight of 740 was used as the dispersant.

[0090] Comparative Example 3. A solid electrolyte composition for an all-solid-state battery of Comparative Example 3-1, a solid electrolyte membrane for an all-solid-state battery of Comparative Example 3-2, and an all-solid-state battery of Comparative Example 3-3 were manufactured in the same manner as in Examples 1-1, 1-2, and 1-3, except that glycolic acid ethoxylate oleyl ether having a weight average molecular weight of 5680 was used as the dispersant.

[0091] Experimental Example 1. Measurement of the dispersed particle size of solid electrolyte in solid electrolyte composition for all-solid-state batteries The dispersed particle size of the solid electrolyte in the solid electrolyte compositions for all-solid-state batteries in Examples 1-1 to 3-1 and Comparative Examples 1-1 to 3-1 was measured using a particle size analyzer.

[0092] The solid electrolyte used in Examples 1-1 to 3-1 and Comparative Examples 1-1 to 3-1 was argyrodite (Li6PS5Cl) having a particle size (D50) of 0.6 to 0.8 μm and a particle size (D99) of 3 to 4 μm, and the dispersed particle size was measured to confirm that the solid electrolyte was dispersed without aggregation in the solid electrolyte composition for an all-solid-state battery.

[0093] The results are shown in Table 1 below and FIG.

[0094] [Table 1]

[0095] In Table 1, the solid electrolyte compositions for all-solid-state batteries of Examples 1-1 to 3-1 of the present invention showed results in which the dispersed particle size (D50) and dispersed particle size (D99) of the solid electrolyte in the composition were very similar to the particle sizes D50 and D99 of the solid electrolyte before dispersion, which indicated that the solid electrolyte was dispersed without agglomeration.

[0096] Comparative Example 1-1 did not contain a dispersant, Comparative Example 2-1 used a carboxylic acid compound with a weight-average molecular weight of less than 1000 as a dispersant, and Comparative Example 3-1 used a carboxylic acid compound with a weight-average molecular weight of more than 5000 as a dispersant. In Comparative Examples 1-1 to 3-1, the solid electrolytes were unable to maintain their particle size within the solid electrolyte composition for all-solid-state batteries and aggregated with each other, resulting in a significant increase in the dispersion particle size (D99). In particular, Comparative Example 1-1, which did not contain a dispersant, exhibited the most frequent aggregation of the solid electrolyte, resulting in a significant increase in the dispersion particle size (D99). Furthermore, even when a dispersant was included, the use of a carboxylic acid compound with a weight-average molecular weight outside the range of 1000 to 5000 resulted in poor dispersion of the solid electrolyte and an increase in the dispersion particle size (D99). Therefore, it was found that Comparative Examples 1-1 to 3-1 exhibited an increase in the dispersion particle size (D99) of the solid electrolyte within the solid electrolyte for all-solid-state batteries, which resulted in the aggregation of the solid electrolyte.

[0097] Experimental Example 2: Measurement of ionic conductivity of solid electrolyte membrane for all-solid-state battery The thickness of the solid electrolyte membranes for all-solid-state batteries of Examples 1-2 to 3-2 and Comparative Examples 1-2 to 3-2 was 30 μm, and the ionic conductivity of the solid electrolyte membranes for all-solid-state batteries was measured.

[0098] The ionic conductivity was measured by assembling a jig cell after placing aluminum foils on the top and bottom of the solid electrolyte membrane for an all-solid-state battery, and applying a pressure of 360 MPa. The results are shown in Table 2 below.

[0099] [Table 2]

[0100] In Examples 1-2 to 3-2, a carboxylic acid compound having a weight-average molecular weight of 1000 to 5000 was used as a dispersant, and the solid electrolyte membranes showed high ionic conductivity.

[0101] Comparative Example 1-2 did not contain a dispersant, Comparative Example 2-2 used a carboxylic acid compound with a weight-average molecular weight of less than 1,000 as a dispersant, and Comparative Example 3-2 used a carboxylic acid compound with a weight-average molecular weight of more than 5,000 as a dispersant. As can be seen from the results of Experimental Example 1, the solid electrolyte was poorly dispersed in the solid electrolyte compositions for all-solid-state batteries of Comparative Examples 1-1 to 3-1, resulting in aggregation. Therefore, when a solid electrolyte membrane for an all-solid-state battery was manufactured using this composition, it was found that a solid electrolyte membrane for an all-solid-state battery with non-uniform thickness and low ionic conductivity was manufactured. In Comparative Example 1-2, the dispersion of the solid electrolyte was very poor, resulting in aggregation of the solid electrolyte. However, since the content of the solid electrolyte was increased by not including a dispersant, the ionic conductivity was similar to that of Comparative Examples 2-2 and 3-2.

[0102] Experimental Example 3: Evaluation of life characteristics of all-solid-state batteries The life characteristics of the all-solid-state batteries of Examples 1-3 to 3-3 and Comparative Examples 1-3 to 3-3 were measured.

[0103] The lifespan characteristics were measured by charging the all-solid-state battery in CCCV mode at 60°C at 0.33C up to 4.25V, discharging it at a constant current down to 3.0V, and measuring the capacity retention rate after 150 charge / discharge cycles.

[0104] The results are shown in Figure 2.

[0105] In Examples 1-3 to 3-3, a carboxylic acid compound having a weight-average molecular weight of 1000 to 5000 was used as a dispersant, and the results showed that the life characteristics of the all-solid-state battery were excellent.

[0106] Comparative Example 1-1 did not contain a dispersant, Comparative Example 2-1 used a carboxylic acid compound with a weight-average molecular weight of less than 1000 as a dispersant, and Comparative Example 3-1 used a carboxylic acid compound with a weight-average molecular weight of more than 5000 as a dispersant. As can be seen from the results of Experimental Example 1, the solid electrolyte was not well dispersed in the solid electrolyte compositions for all-solid-state batteries of Comparative Examples 1-1 to 3-1, and aggregation was observed. As a result, as can be seen from the results of Experimental Example 2, the solid electrolyte films for all-solid-state batteries of Comparative Examples 1-2 to 3-2 showed non-uniform thickness and low ionic conductivity. Therefore, when all-solid-state batteries were manufactured using these compositions, the life characteristics of the all-solid-state batteries were found to be very poor.

[0107] The present invention relates to a solid electrolyte composition for an all-solid-state battery, which uses a carboxylic acid compound having a weight-average molecular weight of 1,000 to 5,000 as a dispersant, and the dispersant prevents the solid electrolyte from agglomerating and disperses it within the composition. Furthermore, a solid electrolyte membrane for an all-solid-state battery manufactured using the solid electrolyte composition for an all-solid-state battery has a uniform thickness and high ionic conductivity, and an all-solid-state battery including the solid electrolyte membrane can exhibit improved life characteristics.

Claims

1. a solid electrolyte, a binder, and a dispersant; The solid electrolyte composition for an all-solid-state battery, wherein the dispersant is a carboxylic acid compound having a weight-average molecular weight of 1,000 or more and 5,000 or less.

2. The particle size D50 of the solid electrolyte is 0.5 μm or more and 1.5 μm or less, and the particle size D99 is 3 μm or more and 5 μm or less, 2. The solid electrolyte composition for an all-solid-state battery according to claim 1, wherein the solid electrolyte has a dispersed particle size D50 of 0.5 μm or more and 1.5 μm or less, and a dispersed particle size D99 of 3 μm or more and 5 μm or less.

3. 3. The solid electrolyte composition for an all-solid-state battery according to claim 2, wherein the dispersion particle size (D99) / dispersion particle size (D50) of the solid electrolyte in the solid electrolyte composition for an all-solid-state battery is 2 or more and 7 or less.

4. 2. The solid electrolyte composition for an all-solid-state battery according to claim 1, wherein the dispersant is at least one selected from the group consisting of glycolic acid ethoxylate lauryl ether, glycolic acid ethoxylate oleyl ether, and glycolic acid ethoxylate 4-tert-butylphenyl ether.

5. 2. The solid electrolyte composition for an all-solid-state battery according to claim 1, wherein the solid electrolyte composition for an all-solid-state battery comprises, relative to a total weight of the solid electrolyte composition, 95% by weight or more and 99% by weight or less of a solid electrolyte, 0.5% by weight or more and 5% by weight or less of a binder, and 0.1% by weight or more and 2% by weight or less of a dispersant.

6. 2. The solid electrolyte composition for an all-solid-state battery according to claim 1, wherein the solid electrolyte comprises 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.

7. 7. The solid electrolyte composition for an all-solid-state battery according to claim 6, wherein the solid electrolyte comprises a sulfide-based solid electrolyte.

8. A solid electrolyte membrane for an all-solid-state battery produced using the solid electrolyte composition for an all-solid-state battery according to any one of claims 1 to 7.

9. 9. The solid electrolyte membrane for an all-solid-state battery according to claim 8, wherein the thickness of the solid electrolyte membrane is 20 μm or more and 50 μm or less.

10. The ionic conductivity of the solid electrolyte membrane is 1.3 × 10 －３ 9. The solid electrolyte membrane for an all-solid-state battery according to claim 8, wherein the solid electrolyte membrane has a specific resistance to water vapor (S / cm) or more.

11. An all-solid-state battery including a positive electrode, a negative electrode, and a solid electrolyte membrane interposed therebetween, 9. An all-solid-state battery, wherein the solid electrolyte membrane is the solid electrolyte membrane according to claim 8.

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