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

Abstract

The present invention relates to a solid electrolyte composition for an all-solid-state battery, and a solid electrolyte membrane and an all-solid-state battery comprising same, wherein the solid electrolyte composition comprises a solvent having a moisture content of 200-2000 ppm.

Description

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

[0001] This application claims the benefit of priority to Korean Patent Application No. 10-2024-0109437, filed August 14, 2024, and Korean Patent Application No. 10-2025-0112935, filed August 14, 2025, the entire contents of which are incorporated herein by reference.

[0002] The present invention relates to a solid electrolyte composition, a solid electrolyte membrane comprising the same, and an all-solid-state battery.

[0003]

[0004] Various batteries are being studied to overcome the limitations of current lithium secondary batteries in terms of battery capacity, safety, output, large-scale development, and miniaturization.

[0005] Representatively, research is being continuously conducted in academia and industry on metal-air batteries with much larger theoretical capacity than lithium secondary batteries, all-solid-state batteries with no risk of explosion in terms of safety, supercapacitors for output, NaS batteries or RFBs (redox flow batteries) for large-scale applications, and thin film batteries for miniaturization.

[0006] All-solid-state batteries replace the liquid electrolytes used in conventional lithium secondary batteries with solid electrolytes. Because they do not use flammable solvents, they eliminate the risk of fire or explosion caused by decomposition reactions of conventional electrolytes, significantly improving safety. Furthermore, because lithium metal or lithium alloys can be used as anode materials, they offer the advantage of dramatically improving the battery's energy density relative to its mass and volume.

[0007] To improve the energy density of all-solid-state batteries, the production of a solid electrolyte membrane is essential. The solid electrolyte membrane can be produced by dispersing a solid electrolyte and a binder in a solvent to produce a slurry-type solid electrolyte composition, coating the solid electrolyte composition on one surface of a release film, drying, and then removing the release film. The properties of the solid electrolyte membrane, such as ionic conductivity, thickness, and film quality, depend on the viscosity of the slurry-type solid electrolyte composition. Therefore, the viscosity of the solid electrolyte composition is very important when producing the solid electrolyte membrane. The viscosity of the solid electrolyte composition is controlled by methods such as adjusting the content of the binder or solid electrolyte. The binder and solid electrolyte are solid components, and the method of controlling the viscosity of the solid electrolyte by adjusting the content of the solid components directly affects the characteristics of the solid electrolyte membrane.

[0008] Improving the coatability of a solid electrolyte composition for manufacturing a solid electrolyte membrane can minimize short circuits, maintain capacity retention, and suppress resistance increase in an all-solid-state battery including the solid electrolyte membrane. The coatability of a solid electrolyte composition depends on its viscosity. If the viscosity is low, coating is impossible, making it difficult to manufacture a solid electrolyte membrane. On the other hand, if the viscosity is high, the thickness of the solid electrolyte membrane becomes thin and uneven, which deteriorates the physical properties of the solid electrolyte membrane. The viscosity increases when the solid content of the solid electrolyte composition is high. Therefore, there is a need for research on a solid electrolyte composition that has a high solid content, low viscosity, and excellent coatability.

[0009]

[0010] [Prior Art Literature]

[0011] [Patent Document]

[0012] Republic of Korea Publication Patent No. 10-2021-0134748

[0013]

[0014] In order to solve the above problem, the inventors of the present invention conducted various studies and confirmed that increasing the moisture content of a solid electrolyte composition for an all-solid-state battery can improve the coating properties of the solid electrolyte composition for an all-solid-state battery without increasing the viscosity of the composition even if the solid content in the composition is high, thereby completing the present invention.

[0015] Accordingly, an object of the present invention is to provide a solid electrolyte composition for an all-solid-state battery having excellent coatability.

[0016] In addition, an object of the present invention is to provide a solid electrolyte membrane manufactured using the solid electrolyte composition.

[0017] In addition, an object of the present invention is to provide an all-solid-state battery having excellent life characteristics by including the solid electrolyte membrane.

[0018]

[0019] To achieve the above purpose,

[0020] The present invention relates to a solid electrolyte composition for an all-solid-state battery, comprising a solid electrolyte, a binder, and a solvent,

[0021] A solid electrolyte composition for an all-solid-state battery is provided, wherein the water content of the solid electrolyte composition is 200 to 2000 ppm.

[0022] In addition, the present invention provides a solid electrolyte membrane for an all-solid-state battery having an average thickness of 55 to 85 μm.

[0023] In addition, the present invention provides a solid electrolyte membrane for an all-solid-state battery, wherein the standard deviation of the thickness of the solid electrolyte membrane for an all-solid-state battery is 1.3 to 2.0 μm.

[0024] In addition, the present invention provides a solid electrolyte membrane for an all-solid-state battery manufactured using the solid electrolyte composition for an all-solid-state battery of the present invention.

[0025] In addition, the present invention provides an all-solid-state battery including a positive electrode; a negative electrode; and a solid electrolyte membrane interposed therebetween, wherein the solid electrolyte membrane is the solid electrolyte membrane of the present invention.

[0026]

[0027] The solid electrolyte composition for an all-solid-state battery of the present invention can reduce the dispersibility of a binder by including moisture, thereby preventing an increase in the viscosity of the solid electrolyte composition even when the solid content in the solid electrolyte composition is high, thereby obtaining the effect of improving the coatability.

[0028] In addition, an all-solid-state battery including a solid electrolyte membrane manufactured using the solid electrolyte composition for an all-solid-state battery of the present invention can have excellent performance.

[0029]

[0030] Hereinafter, the present invention will be described in more detail.

[0031]

[0032] Terms or words used in this specification and claims should not be interpreted as limited to their usual or dictionary meanings, but should be interpreted as meanings and concepts that conform to the technical idea of ​​the present invention, based on the principle that the inventor can appropriately define the concept of the term to explain his or her own invention in the best way.

[0033] The terminology used in the present invention is only used to describe specific embodiments and is not intended to limit the present invention. The singular expression includes the plural expression unless the context clearly indicates otherwise. In the present invention, it should be understood that the terms "comprise" or "have" are intended to specify the presence of a feature, number, step, operation, component, part, or combination thereof described in the specification, but do not exclude in advance the possibility of the presence or addition of one or more other features, numbers, steps, operations, components, parts, or combinations thereof.

[0034]

[0035] Solid electrolyte composition for all-solid-state batteries

[0036] A solid electrolyte membrane for an all-solid-state battery can be manufactured by coating a solid electrolyte composition for an all-solid-state battery on one surface of a release film, drying the same, and then removing the release film. In order to manufacture a solid electrolyte membrane, the solid electrolyte composition for an all-solid-state battery must have excellent coatability. The coatability depends on the viscosity of the solid electrolyte composition for an all-solid-state battery. If the viscosity is low, the solid electrolyte composition for an all-solid-state battery is not coated, making it difficult to manufacture a solid electrolyte membrane for an all-solid-state battery or producing a solid electrolyte membrane for an all-solid-state battery with low ionic conductivity. If the viscosity is excessively high, the solid components clump together, causing a pushing phenomenon in which the coating is excessively thin, resulting in a problem in which a thin solid electrolyte membrane for an all-solid-state battery is manufactured. The viscosity of the solid electrolyte composition for an all-solid-state battery depends on the solid content and increases as the solid content increases.

[0037] In the present invention, the above-mentioned coatability means that coating is possible and easy, and does not mean that the coating thickness is uniform.

[0038] The present invention aims to provide a solid electrolyte composition for an all-solid-state battery having excellent coatability and no increase in viscosity even when the solid content is high.

[0039]

[0040] The present invention relates to a solid electrolyte composition for an all-solid-state battery, comprising a solid electrolyte, a binder, and a solvent.

[0041] The moisture content of the above solid electrolyte composition is 200 to 2000 ppm.

[0042]

[0043] The above solid electrolyte may include a sulfide-based solid electrolyte.

[0044] The above sulfide-based solid electrolyte contains sulfur (S) and has the ionic conductivity of a metal belonging to Group 1 or Group 2 of the periodic table, and may include Li-PS-based glass or Li-PS-based glass ceramic.

[0045] Specifically, the sulfide-based solid electrolyte may include at least one 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 may include at least one selected from the group consisting of Li6PS5Cl, Li6PS5Br, and Li6PS5I. The above Li6PS5Cl, Li6PS5Br, and Li6PS5I may be argyrodite type solid electrolytes. In addition, the sulfide-based solid electrolyte may be in a form doped with trace elements, for example, Li6PS5Cl may be additionally doped with bromine (Br).

[0046] The above binder is not particularly limited in type as long as it is used in the art.

[0047] 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. can be used, but are not limited thereto, and in the present invention, it may be preferable to use a styrene-butadiene-styrene copolymer.

[0048] The above solid electrolyte composition for an all-solid-state battery is in the form of a slurry in which a solid electrolyte and a binder are dispersed in a solvent, and in the solid electrolyte composition for an all-solid-state battery, the solid electrolyte and the binder may be included as a solid component. Therefore, in the present specification, the solid component means a solid electrolyte and a binder.

[0049] The total weight of the solid electrolyte and the binder relative to the total weight of the solid electrolyte composition for the all-solid-state battery may be 40 to 70 wt%, preferably 50 to 60 wt%. The total weight of the solid electrolyte and the binder may be the solid content of the solid electrolyte composition for the all-solid-state battery. If the total weight of the solid electrolyte and the binder is less than 40 wt%, the viscosity of the solid electrolyte composition for the all-solid-state battery becomes too low, so that the solid electrolyte for the all-solid-state battery is not coated on the release film, making it difficult to manufacture a solid electrolyte membrane for the all-solid-state battery, and even if the solid electrolyte membrane for the all-solid-state battery is manufactured, the ionic conductivity is very low. If it exceeds 70 wt%, the viscosity of the solid electrolyte composition for the all-solid-state battery becomes too high, so that a problem may occur in which the coating property deteriorates or the coating is not formed.

[0050] The above solid electrolyte and binder may be mixed in a weight ratio of 90:10 to 99.5:0.5.

[0051] The solid electrolyte composition for an all-solid-state battery of the present invention contains moisture, and the moisture content may be 200 to 2000 ppm, preferably 700 to 1600 ppm. Since the solid electrolyte composition for an all-solid-state battery contains moisture, the dispersibility of the binder is reduced, so that even if the solid content in the solid electrolyte composition for an all-solid-state battery is high, an increase in viscosity can be prevented. Specifically, if the dispersibility of the binder is excellent, the viscosity of the solid electrolyte composition for an all-solid-state battery increases. However, if the dispersibility of the binder is reduced, the binder does not contribute to an increase in the viscosity of the solid electrolyte composition for an all-solid-state battery, so that an increase in viscosity can be prevented, thereby improving the coatability of the solid electrolyte composition for an all-solid-state battery. Therefore, the solid electrolyte composition for an all-solid-state battery of the present invention can have an excellent coatability effect even if the solid content is high because the dispersibility of the binder is reduced because the moisture content is 200 to 2000 ppm. The solid content of the solid electrolyte composition for the above-mentioned all-solid-state battery refers to the total weight of the solid electrolyte and binder, and follows the above-mentioned content. The moisture content of the solid electrolyte composition may be moisture contained in the solvent. Accordingly, the solvent may contain moisture.

[0052] The viscosity of the solid electrolyte composition for the all-solid-state battery may be 4000 to 9000 cP at room temperature, and preferably 4000 to 6000 cP. That is, the solid electrolyte composition for the all-solid-state battery of the present invention may have a viscosity of 4000 to 9000 cP at room temperature even when the total weight of the solid electrolyte and binder, which are solid components, is 40 to 70 wt% based on the total weight of the solid electrolyte composition for the all-solid-state battery, and thus may exhibit excellent coatability.

[0053] If the moisture content of the solid electrolyte composition for the all-solid-state battery is less than 200 ppm, even if the solid content in the solid electrolyte composition for the all-solid-state battery is the same, the viscosity increases, causing the solids to clump together, thereby reducing the coatability of the solid electrolyte composition for the all-solid-state battery. If it exceeds 2000 ppm, the moisture may react with the solid electrolyte, thereby reducing the ionic conductivity of the solid electrolyte membrane for the all-solid-state battery.

[0054] The solvent may include at least one selected from the group consisting of butyl butyrate, xylene, hexane, benzene, anisole, octyl acetate, hexyl butyrate, isobutyl isobutyrate, and toluene, and preferably may include butyl butyrate.

[0055] The moisture content of at least one selected from the group consisting of butyl butyrate, xylene, hexane, benzene, anisole, octyl acetate, hexyl butyrate, isobutyl isobutyrate, and toluene may be 100 to 150 ppm. In the present invention, the solid electrolyte composition for an all-solid-state battery may be prepared by adding distilled water to the composition so that the composition has a moisture content of 200 to 2000 ppm.

[0056]

[0057] Solid electrolyte membrane for all-solid-state batteries

[0058] The present invention relates to a solid electrolyte membrane for an all-solid-state battery having an average thickness of 55 to 85 μm.

[0059] In addition, the present invention relates to a solid electrolyte membrane for an all-solid-state battery, wherein the standard deviation of the thickness of the solid electrolyte membrane for an all-solid-state battery is 1.3 to 2.0 μm.

[0060] In addition, the present invention relates to a solid electrolyte membrane for an all-solid-state battery manufactured using the solid electrolyte composition for an all-solid-state battery of the present invention described above.

[0061] The above solid electrolyte membrane for an all-solid-state battery can be manufactured by a method of applying the above solid electrolyte composition for an all-solid-state battery to one surface of a release film, drying it, and then removing the release film.

[0062] The solid electrolyte membrane for the above-described all-solid-state battery may be manufactured using the solid electrolyte composition for the all-solid-state battery of the present invention described above. Accordingly, the solid electrolyte, binder, and solvent are as described above.

[0063] The solid electrolyte composition for an all-solid-state battery of the present invention contains 200 to 2000 ppm of moisture. The moisture content can reduce the dispersibility of the binder. As described above, when the dispersibility of the binder is reduced, even if the solid content in the solid electrolyte composition for an all-solid-state battery is high, an increase in viscosity can be prevented, and thus the solid electrolyte composition for an all-solid-state battery of the present invention has an excellent coatability effect.

[0064] In addition, the average thickness of the solid electrolyte membrane for an all-solid-state battery manufactured using the solid electrolyte composition for an all-solid-state battery of the present invention may be 55 to 85 μm.

[0065] The standard deviation of the thickness of the solid electrolyte membrane for the all-solid-state battery may be 1.3 to 2.0 μm, and preferably 1.3 to 1.8 μm. The standard deviation of the thickness of the solid electrolyte membrane may be calculated by measuring the thickness at about 10 points. The standard deviation of the thickness of the solid electrolyte membrane may mean that the binder is unevenly distributed. That is, the binder may not be dispersed in the solid electrolyte membrane but may be clumped together, causing the solid electrolyte membrane to have the thickness standard deviation. However, even if the solid electrolyte membrane for the all-solid-state battery of the present invention has the thickness standard deviation, the coating of the solid electrolyte composition for the all-solid-state battery is not uneven, and it may be the standard deviation of a solid electrolyte membrane in which the coating is uniformly formed.

[0066]

[0067] All-solid-state batteries

[0068] In addition, the present invention relates to an all-solid-state battery including a positive electrode; a negative electrode; and a solid electrolyte membrane interposed therebetween; wherein the solid electrolyte membrane may be the solid electrolyte membrane for the all-solid-state battery of the present invention described above.

[0069] The above all-solid-state battery is a lithium secondary battery, and there is no limitation on the positive or negative electrode, and it may be a lithium-air battery, a lithium oxide battery, a lithium-sulfur battery, or a lithium metal battery.

[0070]

[0071] The above positive electrode may include a positive electrode current collector and a positive electrode active material layer applied to one or both sides of the positive electrode current collector.

[0072] The above positive electrode current collector is intended 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 the lithium secondary battery. For example, the positive electrode current collector may be any one 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. As the alloy, an aluminum-cadmium alloy may be preferably used. In addition, calcined carbon, a non-conductive polymer surface-treated with a conductive material, or a conductive polymer may be used.

[0073] The above-mentioned positive electrode current collector can form fine irregularities on its surface to strengthen the bonding strength with the positive electrode active material, and can be used in various forms such as a film, sheet, foil, mesh, net, porous body, foam, and non-woven fabric.

[0074] The above positive electrode active material layer may optionally include a conductive material and a binder together with the positive electrode active material and the solid electrolyte.

[0075] The above 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; chemical formula Li 1+x Mn 2-x Lithium manganese oxides such as O4(0≤x≤0.33), LiMnO3, LiMn2O3, LiMnO2; lithium copper oxide (Li2CuO2); vanadium oxides such as LiV3O8, V2O5, Cu2V2O7; chemical formula LiNi 1-x M x Ni-site lithium nickel oxide represented by O2 (M = Co, Mn, Al, Cu, Fe, Mg, B or Ga; 0.01≤x≤0.3); chemical formula LiMn 2-x M x Lithium manganese composite oxides expressed as 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 spinel structure represented by O4; LiCoPO4; LiFePO4; Elemental sulfur (S8); Li2S n (n=1), organosulfur compounds or carbon-sulfur polymers (C2S x ) n : It may include sulfur series compounds such as x=2.5 ~ 50, n≥2), but is not limited to these.

[0076] The positive electrode active material may be included in an amount of 65 to 95 wt% based on the total weight of the positive electrode active material layer. Specifically, the content of the positive electrode active material may be 65 wt% or more, 70 wt% or more, 75 wt% or more, or 80 wt% or more. It may be 95 wt% or less, 90 wt% or less, or 85 wt% or less. If the content of the positive electrode active material is less than 65 wt%, battery performance may deteriorate, and if it exceeds 95 wt%, mass transfer resistance may increase.

[0077] The above conductive material is a material that electrically connects the electrolyte and the positive electrode active material and serves as a path for electrons to move from the current collector to the positive electrode active material. Any material that does not cause chemical changes in a lithium secondary battery and has porosity and conductivity can be used without restriction.

[0078] For example, the conductive material may be a porous carbon-based material, such as carbon black, graphite, graphene, activated carbon, carbon fiber, etc.; metallic fibers such as metal mesh; metallic powders such as copper, silver, nickel, aluminum, etc.; or organic conductive materials such as polyphenylene derivatives. The conductive materials may be used alone or in combination.

[0079] Current commercially available products include acetylene black series (such as those from Chevron Chemical Company or Gulf Oil Company), Ketjen Black EC series (from Armak Company), Vulcan XC-72 (from Cabot Company), and Super P (from MMM). Examples include acetylene black, carbon black, and graphite.

[0080] The conductive material may be included in an amount of more than 0 wt% and less than 5 wt% based on the total weight of the positive electrode active material layer, and specifically, the content of the conductive material may be 0.1 wt% or more, 0.5 wt% or more, 1 wt% or more, 1.5 wt% or more, or 2 wt% or more, and may be 5 wt% or less, 4 wt% or less, or 3 wt% or less. If the conductive material is not included, it is difficult to expect an effect of improving electrical conductivity or the electrochemical characteristics of the battery may deteriorate, and if it exceeds 5 wt% and is too much, the amount of the positive electrode active material may be relatively small, which may result in a decrease in capacity and energy density.

[0081] In addition, the binder increases the bonding strength between the components constituting the positive electrode and between them and the current collector, and any binder known in the industry can be used.

[0082] For example, the binder may be a fluororesin binder including polyvinylidene fluoride (PVdF) or polytetrafluoroethylene (PTFE); a rubber binder including styrene butadiene rubber (SBR), acrylonitrile-butidiene rubber, and styrene-isoprene rubber; a cellulose binder including carboxyl methyl cellulose (CMC), starch, hydroxy propyl cellulose, and regenerated cellulose; a polyalcohol binder; a polyolefin binder including polyethylene and polypropylene; a polyimide binder; a polyester binder; and a silane binder. One, two or more mixtures or copolymers selected from the group consisting of may be used.

[0083] In addition, the binder may be included in an amount of 0.1 to 5 wt% based on the total weight of the positive electrode active material layer. Specifically, the content of the binder may be 0.1 wt% or more, 0.5 wt% or more, or 0.8 wt% or more, and may be 5 wt% or less, 4 wt% or less, 3 wt% or less, 2 wt% or less, or 1.5 wt% or less. If the content of the binder is less than 0.1 wt%, the effect of improving the bonding strength between materials included in the positive electrode active material layer may be minimal, and thus the electrode sheet may not be properly formed. If the content of the binder is more than 5 wt%, the ionic conductivity or electrical conductivity of the positive electrode may be reduced.

[0084] The above solid electrolyte follows the solid electrolyte described above in the solid electrolyte composition for an all-solid-state battery.

[0085] The positive electrode active material layer is formed by applying a composition for forming a positive electrode active material layer, which includes a positive electrode active material, a solid electrolyte, and a binder, onto a current collector, and the composition may not contain a solvent. Accordingly, the positive electrode for an all-solid-state battery of the present invention may be a dry positive electrode. Alternatively, the positive electrode active material layer is formed by applying a composition for forming a positive electrode active material layer, which includes a positive electrode active material, a solid electrolyte, a binder, and a solvent, onto a current collector, and the positive electrode for an all-solid-state battery of the present invention may be a wet positive electrode.

[0086]

[0087] The above-mentioned negative electrode may include a negative electrode current collector and a negative electrode active material layer positioned on the negative electrode current collector. In addition, the negative electrode, like the positive electrode, may include a conductive material and a binder as needed. In this case, the negative electrode current collector, conductive material, and binder are as described above.

[0088] The above negative active material is lithium ion (Li +) can be reversibly intercalated or deintercalated, or any material that can react with lithium ions to form a reversibly lithium-containing compound.

[0089] For example, the negative active material may be at least one carbon-based material 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 material, Li x Fe2O3(0≤x≤1), Li x WO2(0≤x≤1), Sn x Me 1-x Me´ y O z (Me: Mn, Fe, Pb, Ge; Me´: Al, B, P, Si, elements of group 1, 2, and 3 of the periodic table, halogens; 0 <x≤1; 1≤y≤3; 1≤z≤8) 등의 금속 복합 산화물; 리튬 금속; 리튬 합금; 규소계 합금; 주석계 합금; SnO, SnO2, PbO, PbO2, Pb2O3, Pb3O4, Sb2O3, Sb2O4, Sb2O5, GeO, GeO2, Bi2O3, Bi2O4, Bi2O5등의 금속 산화물; 폴리아세틸렌 등의 도전성 고분자; Li-Co-Ni 계 재료; 티타늄 산화물; 리튬 티타늄 산화물 등을 포함할 수 있지만, 이들만으로 한정되는 것은 아니다.

[0090] Additionally, the negative electrode may include a negative electrode current collector and a coating layer including metal-carbon composite particles positioned on the negative electrode current collector. This may mean an anodeless electrode that does not include a negative electrode active material.

[0091] The above negative electrode may be such that when the all-solid-state battery is charged, lithium ions pass through the coating layer to reach the surface of the negative electrode current collector, and these are deposited to form a lithium metal layer.

[0092] The above metal-carbon composite particles may have a form in which carbon particles and metal particles are attached to each other or one surface is coated with the other, and may be physically or chemically bonded.

[0093] The above 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, fullerene, carbon fiber, and fluorocarbon.

[0094] The above metal particles are lithium-philic metals, for example, Ni, Cu, Ag, Au, Pt, Al, Zn, Bi, etc., and may be one or a combination of two or more thereof. By introducing a metal having the above lithium-philic properties, it is advantageous to form a stable and uniform lithium layer on the surface of the current collector.

[0095] The above 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 applying and drying the slurry on a negative electrode current collector. In this case, the binder may be a conventional binder used in the art.

[0096] The manufacture of the above all-solid-state battery is not particularly limited in the present invention, and a known method can be used.

[0097] For example, a solid electrolyte membrane is placed between the positive and negative electrodes, and then compressed to assemble the cell. The assembled cell is then installed within an outer packaging material and sealed by heating and compression, etc. The outer packaging material may be a laminate pack made of aluminum, stainless steel, or a metal container such as a cylindrical or square shape.

[0098] For example, the negative electrode is manufactured through a slurry coating process in which a slurry composition comprising a negative electrode active material, a solvent, and a binder is prepared, and the same is coated and then dried. The positive electrode is manufactured through a composition for forming a positive electrode active material layer comprising a positive electrode active material and a binder, or through a slurry coating process in which a slurry composition comprising a positive electrode active material, a binder, and a solvent is prepared, and the same is coated and then dried.

[0099] Methods for coating the electrode slurry on the current collector include a method of distributing the electrode slurry on the current collector and then uniformly dispersing it using a doctor blade or the like, die casting, comma coating, screen printing, etc. In addition, the electrode slurry may be formed on a separate substrate and then bonded to the current collector by pressing or lamination. At this time, the final coating thickness can be controlled by adjusting the concentration of the slurry solution or the number of coatings.

[0100] The drying process is a process of removing the solvent and moisture within the slurry to dry the slurry coated on the metal collector. This process 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 using warm air, hot air, or low-humidity air, vacuum drying, and drying using irradiation with (far) infrared rays or electron beams. The drying time is not particularly limited, but is typically performed within the range of 30 seconds to 24 hours.

[0101] After the above drying process, a cooling process may be further included, and the cooling process may be slow cooling to room temperature so that the recrystallized structure of the binder is well formed.

[0102] Additionally, if necessary, after the drying process, a rolling process may be performed to compress the electrode to a desired thickness by passing it between two high-temperature heated rolls to increase the capacity density of the electrode and enhance the adhesion between the current collector and the active materials. The rolling process is not particularly limited in the present invention, and any known pressing process is possible. For example, it may be performed by passing it between rotating rolls or using a flat plate press.

[0103] The shape of the above-mentioned all-solid-state battery is not particularly limited, and can be made into various shapes such as cylindrical, laminated, and coin-shaped.

[0104]

[0105] The solid electrolyte membrane of the above-described all-solid-state battery is manufactured using the solid electrolyte composition for the all-solid-state battery of the present invention described above, and thus has a uniform thickness. Accordingly, the all-solid-state battery can have the effects of minimizing the occurrence of short circuits, suppressing the rate of resistance increase, and improving the capacity retention rate.

[0106]

[0107] Hereinafter, preferred examples are presented to help understand the present invention, but the following examples are only illustrative of the present invention, and it is obvious to those skilled in the art that various changes and modifications are possible within the scope and technical idea of ​​the present invention, and it is also natural that such changes and modifications fall within the scope of the appended patent claims.

[0108]

[0109] Example 1.

[0110] Example 1-1. Preparation of a solid electrolyte composition for an all-solid-state battery

[0111] A butyl butyrate solvent having a moisture content of 800 ppm was prepared by adding 0.2 mL of distilled water to 250 mL of butyl butyrate containing 150 ppm of moisture and stirring at room temperature for 24 hours.

[0112] A solid electrolyte composition for an all-solid-state battery in the form of a slurry of Example 1-1 was prepared by adding a solid electrolyte and a binder to the above solvent.

[0113] The solid electrolyte is a solid electrolyte substituted with agarodite (Li6PS5Cl) and a halide (Li x PS y Cl z Br p ) was used, and polybutadiene was used as a binder. The solid electrolyte and binder were mixed at a weight ratio of 98:2.

[0114] The solid content of the solid electrolyte composition for the all-solid-state battery of Example 1-1 was 54 wt%, and the solid content is the total weight of the solid electrolyte and binder.

[0115] In addition, the viscosity of the solid electrolyte composition for an all-solid-state battery of Example 1-1 is 4600 cP at room temperature, and the moisture content is 800 ppm.

[0116]

[0117] Example 1-2. Preparation of a solid electrolyte membrane for an all-solid-state battery

[0118] Polyethylene terephthalate was used as a release film, 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. Thereafter, the film was dried at 70°C 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.

[0119]

[0120] Example 1-3. Manufacturing of all-solid-state batteries

[0121] A positive electrode active material (NCM 811), a conductive agent (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 positive electrode current collector and then rolled to manufacture a dry positive electrode.

[0122] A negative electrode was manufactured by applying a mixture of a negative electrode active material (silver-carbon composite particles) and a binder (polyvinylidene fluoride) to a thickness of 20 μm on a 10 μm thick SUS, which is a negative electrode collector.

[0123] An all-solid-state battery of Example 1-3 was manufactured by interposing the solid electrolyte membrane manufactured in Example 1-2 between the positive and negative electrodes.

[0124]

[0125] Example 2.

[0126] A butyl butyrate solvent having a moisture content of 1500 ppm was prepared by adding 0.35 mL of distilled water to 250 mL of butyl butyrate containing 150 ppm of moisture and stirring at room temperature for 24 hours.

[0127] Thereafter, the solid electrolyte composition for an all-solid-state battery of Example 2-1 in the form of a slurry was manufactured in the same manner as in Example 1-1.

[0128] The solid content of the solid electrolyte composition for the all-solid-state battery of Example 2-1 was 54 wt%, and the solid content is the total weight of the solid electrolyte and binder.

[0129] In addition, the viscosity of the solid electrolyte composition for an all-solid-state battery of Example 2-1 is 4200 cP at room temperature, and the moisture content is 1500 ppm.

[0130] In addition, the solid electrolyte membrane for an all-solid-state battery of Example 2-2 and the all-solid-state battery of Example 2-3 were manufactured in the same manner as in Examples 1-2 and 1-3.

[0131]

[0132] Comparative Example 1.

[0133] A solid electrolyte composition for an all-solid-state battery of Comparative Example 1-1 in the form of a slurry was prepared in the same manner as in Example 1-1, except that only butyl butyrate containing 150 ppm of moisture was used as a solvent.

[0134] The solid content of the solid electrolyte composition for the all-solid-state battery of Comparative Example 1-1 was 54 wt%, and the solid content is the total weight of the solid electrolyte and binder.

[0135] In addition, the viscosity of the solid electrolyte composition for an all-solid-state battery of Comparative Example 1-1 is 9200 cP at room temperature, and the moisture content is 150 ppm.

[0136] In addition, the solid electrolyte membrane for an all-solid-state battery of Comparative Example 1-2 and the all-solid-state battery of Comparative Example 1-3 were manufactured in the same manner as in Examples 1-2 and 1-3.

[0137]

[0138] Experimental Example 1. Measurement of the average thickness and standard deviation of the thickness of a solid electrolyte membrane for an all-solid-state battery.

[0139] The average thickness and standard deviation of the thickness of the solid electrolyte membrane for the all-solid-state battery of Example 1-2, Example 2-2, and Comparative Example 1-2 were measured.

[0140] The thickness of the solid electrolyte membranes for all-solid-state batteries of Examples 1-2, 2-2, and Comparative Example 1-2 was measured at 12 points arranged at regular intervals using a thickness measuring device measuring in micrometers, and the average thickness of the solid electrolyte membranes for all-solid-state batteries was obtained using the thicknesses at the 12 points. In addition, the standard deviation of the thickness was obtained using the thicknesses at the 12 points, and the results are shown in Table 1 below.

[0141]

[0142] Average thickness (μm)Standard deviation (μm)Example 1-256.91.7Example 2-257.21.7Comparative example 1-254.41.19

[0143] The purpose of Example 1-2, Example 2-2, and Comparative Example 1-2 was to manufacture a solid electrolyte membrane having an average thickness of 55 μm or more. The average thickness of the solid electrolyte membranes for all-solid-state batteries of Example 1-2 and Example 2-2 was 55 μm or more, whereas the average thickness of the solid electrolyte membrane for all-solid-state batteries of Comparative Example 1-2 was less than 55 μm.

[0144] The above solid electrolyte membrane for an all-solid-state battery is manufactured using a solid electrolyte composition for an all-solid-state battery. Although the solid content of the compositions of Example 1-1, Example 2-1, and Comparative Example 1-1 is the same, they have different viscosities. This is because the moisture content of the compositions is different from each other.

[0145] The viscosities of Examples 1-1 and 2-1 were 4600 and 4200 cP, respectively, indicating excellent coating properties. Therefore, the coating did not slide off.

[0146] On the other hand, the viscosity of Comparative Example 1-1 was 9200 cP, which was higher than that of Examples 1-1 and 2-1. Therefore, the solid electrolyte composition for an all-solid-state battery of Comparative Example 1-1 had very poor coatability, resulting in a phenomenon of the coating being pushed out. Therefore, it was confirmed that the solid electrolyte membrane for an all-solid-state battery of Comparative Example 1-2 was manufactured to be thinner than the solid electrolyte membranes for an all-solid-state battery of Examples 1-2 and 2-2, and was not manufactured to the desired average thickness.

[0147] The solid electrolyte composition for an all-solid-state battery of the present invention can reduce the dispersibility of the binder within the composition due to its moisture content of 200 to 2,000 ppm, thereby preventing an increase in the viscosity of the solid electrolyte composition. Since the dispersibility of the binder is reduced, the binder is not dispersed but clumps together in the solid electrolyte membrane, which can be confirmed from the standard deviation of the thickness of the solid electrolyte membrane.

[0148] If the dispersibility of the binder is poor, the viscosity of the solid electrolyte composition for an all-solid-state battery does not increase, which means that the coatability is excellent. From the standard deviation of the thickness of the solid electrolyte membranes of Examples 1-2 and 2-2, it can be confirmed that the binder is unevenly distributed, and from this, it can be seen that coating is easily achieved. On the other hand, if the dispersibility of the binder is good, the viscosity of the solid electrolyte composition for an all-solid-state battery increases, resulting in poor coatability. The viscosity of the solid electrolyte composition of Comparative Example 1-1 was high, resulting in poor coatability, and from the standard deviation of the thickness of the solid electrolyte membrane of Comparative Example 1-2, it could be confirmed that the binder was uniformly dispersed.

[0149]

[0150] Experimental Example 2. Measurement of the life characteristics of an all-solid-state battery.

[0151] The life characteristics of the all-solid-state batteries of Examples 1-3, 2-3, and Comparative Example 1-3 were measured.

[0152] The life characteristics were measured by charging the all-solid-state battery at 0.33C in CCCV mode at a temperature of 60℃ to 4.3V, and discharging it to 2.5V with a constant current for 100 charge and discharge cycles, and the initial discharge capacity and capacity retention rate were measured. The results are shown in Table 2 below.

[0153]

[0154] Initial discharge capacity (mAh / g) Capacity retention rate (%) Example 1 - 3192.796.6 @ 80 cycles Example 2 - 3189.698.4 @ 80 cycles Comparative example 1 - 3181.794.4 @ 80 cycles

[0155] In the results in Table 2 above, the all-solid-state batteries of Examples 1-3 and 2-3 showed better results in both initial discharge capacity and capacity retention rate than the all-solid-state battery of Comparative Example 1-3. The solid electrolyte compositions for all-solid-state batteries of Examples 1-1, 2-1, and Comparative Example 1-1 have the same solid content in the compositions. However, the moisture contents of the solid electrolyte compositions for all-solid-state batteries are 800, 1500, and 150 ppm, respectively, and accordingly, the viscosities at room temperature are 4600, 4200, and 9200 cP, respectively. The solid electrolyte composition for all-solid-state batteries of Comparative Example 1-1 had high viscosity, resulting in poor coatability, and as a result, the coating was pushed during the manufacture of the solid electrolyte membrane for the all-solid-state battery. Therefore, the all-solid-state battery of Comparative Example 1-3 showed worse results in initial discharge capacity and capacity retention rate than Examples 1-3 and 2-3.

[0156]

[0157] The present invention relates to a solid electrolyte composition for an all-solid-state battery having a moisture content of 200 to 2000 ppm, wherein the moisture content reduces the dispersibility of a binder, so that even if the solid content in the composition is 40 to 70 wt%, the composition can have a viscosity of 4000 to 9000 cP without an increase in viscosity, thereby achieving an excellent coatability effect. Accordingly, an all-solid-state battery including a solid electrolyte membrane for an all-solid-state battery manufactured using the solid electrolyte composition for an all-solid-state battery can obtain improved life characteristics.

Claims

1. A solid electrolyte composition for an all-solid-state battery comprising a solid electrolyte, a binder, and a solvent, A solid electrolyte composition for an all-solid-state battery, wherein the moisture content of the solid electrolyte composition is 200 to 2000 ppm.

2. In paragraph 1, A solid electrolyte composition for an all-solid-state battery, wherein the moisture content of the solid electrolyte composition is 700 to 1600 ppm.

3. In paragraph 1, A solid electrolyte composition for an all-solid-state battery, wherein the total weight of the solid electrolyte and the binder is 40 to 70 wt% based on the total weight of the solid electrolyte composition for an all-solid-state battery.

4. In paragraph 3, A solid electrolyte composition for an all-solid-state battery, wherein the solid electrolyte and binder are mixed in a weight ratio of 90:10 to 99.5:0.

5.

5. In paragraph 3, A solid electrolyte composition for an all-solid-state battery, wherein the viscosity of the solid electrolyte composition for an all-solid-state battery at room temperature is 4000 to 9000 cP.

6. In paragraph 1, A solid electrolyte composition for an all-solid-state battery, wherein the solvent comprises at least one selected from the group consisting of butyl butyrate, xylene, hexane, benzene, anisole, octyl acetate, hexyl butyrate, isobutyl isobutyrate, and toluene.

7. In paragraph 1, A solid electrolyte composition for an all-solid-state battery, wherein the solid electrolyte comprises a sulfide-based solid electrolyte.

8. A solid electrolyte membrane for an all-solid-state battery, wherein the average thickness of the solid electrolyte membrane for an all-solid-state battery is 55 to 85 μm.

9. A solid electrolyte membrane for an all-solid-state battery, wherein the standard deviation of the thickness of the solid electrolyte membrane for an all-solid-state battery is 1.3 to 2.0 μm.

10. A solid electrolyte membrane for an all-solid-state battery manufactured using the solid electrolyte composition for an all-solid-state battery of paragraph 1.

11. An all-solid-state battery comprising a positive electrode; a negative electrode; and a solid electrolyte membrane interposed therebetween; An all-solid-state battery, wherein the above solid electrolyte membrane is the solid electrolyte membrane of claim 10.