All-solid-state battery and method for manufacturing same

Abstract

The present invention relates to an all-solid-state battery and a manufacturing method therefor, wherein a solid electrolyte present at an interface between a negative electrode active material layer and a solid electrolyte layer has an average particle size of 1 to 3 μm.

Description

All-solid-state battery and method for manufacturing the same

[0001] This application claims the benefit of priority to Korean Patent Application No. 10-2024-0040201, dated March 25, 2024, the entire disclosure of which is incorporated herein by reference.

[0002] The present invention relates to an all-solid-state battery and a method for manufacturing the same.

[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] Representative examples include 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, all of which are being continuously researched in academia and industry.

[0006] An all-solid-state battery is a battery that replaces the liquid electrolyte used in conventional lithium secondary batteries with a solid one. Since it does not use flammable solvents in the battery, there is no risk of fire or explosion due to decomposition reactions of conventional electrolytes, so safety can be significantly improved.

[0007] An all-solid-state battery can be manufactured by interposing a solid electrolyte layer between an anode and a cathode and then performing high-pressure pressing. The solid electrolyte layer can be formed in the all-solid-state battery by using a free-standing solid electrolyte layer, transferring the solid electrolyte layer to an electrode, or applying a composition for forming a solid electrolyte layer to an electrode. Among these, the method of applying a composition for forming a solid electrolyte layer to the electrode has the advantages of high process efficiency and the ability to realize a thin-film solid electrolyte layer.

[0008] The above composition for forming a solid electrolyte layer is in a slurry state including a solid electrolyte, a binder, and a solvent. If the negative electrode active material layer includes a carbon-based material as the negative electrode active material, the porosity of the negative electrode active material layer is high, and a phenomenon occurs in which the solvent of the composition for forming a solid electrolyte layer penetrates into the pores of the negative electrode active material layer. At this time, the solid electrolyte and binder particles, etc., penetrate into the pores together with the solvent and are located at the interface between the negative electrode active material layer and the solid electrolyte layer, which may cause a problem in that the irreversible capacity of the all-solid-state battery increases and the life characteristics deteriorate.

[0009] Therefore, there is a need for research to prevent the solid electrolyte from penetrating into the coating layer during the process of applying a composition for forming a solid electrolyte layer to the negative electrode active material layer.

[0010]

[0011] [Previous literature]

[0012] [Patent Document]

[0013] Republic of Korea Publication Patent No. 10-2023-01155924

[0014]

[0015] In order to solve the above problem, the inventors conducted a multifaceted study and as a result,

[0016] The present invention was completed by confirming that the solid electrolyte penetrating into the pores of the negative electrode active material layer can be reduced when the average particle size of the solid electrolyte present at the interface between the negative electrode active material layer and the solid electrolyte layer is 1 to 3 μm.

[0017] Accordingly, the present invention provides an all-solid-state battery having improved life characteristics by preventing a solid electrolyte from penetrating into a negative electrode active material layer.

[0018] In addition, an object of the present invention is to provide a method for manufacturing the all-solid-state battery.

[0019]

[0020] To achieve the above purpose,

[0021] The present invention comprises a positive electrode including a positive electrode active material layer; a negative electrode including a negative electrode active material layer; and a solid electrolyte layer including a solid electrolyte interposed between the positive electrode active material layer and the negative electrode active material layer.

[0022] The above negative electrode active material layer includes a carbon-based material as the negative electrode active material,

[0023] An all-solid-state battery is provided, wherein the average particle size of the solid electrolyte present at the interface between the negative active material layer and the solid electrolyte layer is 1 to 3 μm.

[0024] In addition, the present invention comprises the steps of (1) preparing a composition for forming a negative electrode active material layer by mixing a negative electrode active material, a binder, and a solvent;

[0025] (2) A step of forming a negative electrode active material layer by applying and drying the composition for forming the negative electrode active material layer on a negative electrode current collector;

[0026] (3) A step of manufacturing a negative electrode by pressurizing the negative electrode active material layer;

[0027] (4) A step of preparing a composition for forming a solid electrolyte layer by mixing a solid electrolyte, a binder, and a solvent;

[0028] (5) A step of manufacturing a solid electrolyte layer by applying and drying the composition for forming the solid electrolyte layer on the negative electrode active material layer; and

[0029] (6) The present invention provides a method for manufacturing an all-solid-state battery, including a step of laminating a positive electrode on the solid electrolyte layer.

[0030]

[0031] The all-solid-state battery of the present invention can reduce the solid electrolyte penetrating into the pores of the anode active material layer since the average particle size of the solid electrolyte present at the interface between the anode active material layer and the solid electrolyte layer is 1 to 3 μm, thereby reducing the side reactions and irreversible capacity of the anode active material and the solid electrolyte during operation of the all-solid-state battery, and can have the effect of improving the life characteristics.

[0032]

[0033] Figure 1 is an interface photograph of the all-solid-state battery of Example 1.

[0034] Figure 2 is an interface photograph of the all-solid-state battery of Comparative Example 1.

[0035] Figure 3 is a graph showing the life characteristics of the all-solid-state battery of Experimental Example 1.

[0036]

[0037] Hereinafter, the present invention will be described in more detail.

[0038]

[0039] Terms or words used in this specification and claims should not be interpreted in their usual or dictionary meanings, but should be interpreted in their meanings and concepts that are consistent with the technical spirit of the present invention, based on the principle that the inventor can appropriately define the concept of the term to best explain his or her own invention.

[0040] 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.

[0041]

[0042] All-solid-state batteries

[0043] The present invention comprises a positive electrode including a positive electrode active material layer; a negative electrode including a negative electrode active material layer; and a solid electrolyte layer including a solid electrolyte interposed between the positive electrode active material layer and the negative electrode active material layer.

[0044] The above negative electrode active material layer includes a carbon-based material as the negative electrode active material,

[0045] The present invention relates to an all-solid-state battery, wherein the average particle size of the solid electrolyte present at the interface between the negative active material layer and the solid electrolyte layer is 1 to 3 μm.

[0046]

[0047] The negative electrode including the above negative electrode active material layer may include a negative electrode current collector and a negative electrode active material layer on the negative electrode current collector.

[0048] The above negative electrode current collector is intended to support the negative 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 all-solid-state battery. For example, the above negative 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 or a conductive polymer surface-treated with a conductive material, etc. may be used.

[0049] The above negative electrode current collector can form fine irregularities on its surface to strengthen the bonding strength with the negative 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.

[0050] The above-mentioned negative electrode active material layer may include a carbon-based material as the negative electrode active material. An anode including a carbon-based material as the negative electrode active material may be referred to as an anodeless.

[0051] If the negative electrode of the above-mentioned all-solid-state battery is a non-negative electrode, lithium ions that move from the positive electrode when the all-solid-state battery is charged can be precipitated and stored in the form of lithium metal (Li) between the negative electrode active material layer and the negative electrode current collector, thereby forming a lithium metal layer.

[0052] The above carbon-based material may include at least one selected from the group consisting of 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 fluorinated carbon, and preferably may include carbon black.

[0053] In addition, the negative electrode active material layer may additionally include a metal, and when the metal is included, lithium metal (Li) may be formed more smoothly and flatly between the negative electrode active material layer and the negative electrode current collector.

[0054] The above metal is a lithiophilic metal and may include at least one selected from the group consisting of nickel, copper, silver, gold, platinum, aluminum, zinc, palladium, and bismuth.

[0055] The above-described negative electrode active material layer may additionally include a binder. The binder increases the bonding strength between the negative electrode active material and the negative electrode current collector, and the type of binder is not particularly limited as long as it is one used in the art.

[0056] 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. A mixture or copolymer of one or more of the following may be used.

[0057] The porosity of the negative electrode active material layer may be 15 to 40%, preferably 15 to 30%. In addition, the average diameter of the pores of the negative electrode active material layer may be less than 0.5 to 0.7 μm.

[0058] A solid electrolyte layer can be formed by applying a composition for forming a solid electrolyte layer on a negative electrode active material layer. The composition for forming a solid electrolyte layer is in the form of a slurry, and a phenomenon occurs in which a solvent of the slurry penetrates into the pores of the negative electrode active material layer. Generally, if the negative electrode active material is a carbon-based material, the porosity of the negative electrode active material layer is high, so that when the solvent of the slurry penetrates into the pores of the negative electrode active material layer, the solid electrolyte particles included in the composition for forming a solid electrolyte layer also penetrate, so that the solid electrolyte particles are positioned at the interface between the negative electrode active material layer and the solid electrolyte layer. If the solid electrolyte particles are positioned at the interface, the irreversible capacity of the all-solid-state battery may increase, and problems with poor cycle characteristics may occur. In the present specification, when the average particle size of the solid electrolyte is less than 1 μm, it means that the solid electrolyte is in the form of particles.

[0059] However, even if the negative electrode active material layer of the all-solid-state battery of the present invention includes a carbon-based material as the negative electrode active material, the above problem can be solved as the negative electrode active material layer has the above porosity and the average diameter of the pores.

[0060] The average particle size (D50) of the above solid electrolyte may be 2 to 4 μm, and D10 may be fine particles less than 1 μm. In addition, D90 may be 5 to 8 μm. The average particle size (D50) of the above solid electrolyte is 2 to 4 μm, but the average particle size (D50) of the solid electrolyte present at the interface between the negative electrode active material layer and the solid electrolyte layer may be 1 to 3 μm, and preferably 1 to 2 μm. This means that since the negative electrode active material layer has the above porosity and the average diameter of the pores, the penetration of the fine particle solid electrolyte into the pores of the negative electrode active material layer is reduced. Therefore, the all-solid-state battery of the present invention may have a low irreversible capacity and excellent life characteristics. If the porosity of the negative active material layer exceeds 40% or the average pore diameter is 0.7 μm or more, the penetration of the fine particle solid electrolyte into the pores of the negative active material layer increases, and the average particle size of the solid electrolyte present at the interface between the negative active material layer and the solid electrolyte layer may be less than 1 μm. Accordingly, the irreversible capacity of the all-solid-state battery may increase and the life characteristics may deteriorate. The above average particle size D50 refers to the particle size at which the volume accumulation amount corresponds to 50% in the particle size distribution curve of the particles.

[0061] The positive electrode including the positive electrode active material layer may include a positive electrode current collector and a positive electrode active material layer on the positive electrode current collector.

[0062] The above positive electrode collector is the same as the negative electrode collector described above.

[0063] The above positive electrode active material layer may include a positive electrode active material and optionally a conductive material or a binder, wherein the binder is as described above.

[0064] 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.

[0065] 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.

[0066] 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.

[0067] 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.

[0068] The above solid electrolyte layer includes a solid electrolyte, and the solid electrolyte may include 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, and preferably includes a sulfide-based solid electrolyte.

[0069] 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.

[0070] 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).

[0071] The above polymer-based solid electrolyte is a polymer electrolyte material formed by adding a polymer resin to a composite of a lithium salt and a polymer resin, that is, a solvated lithium salt, and is about 1x10 -7 S / cm or more, preferably about 1x10 -5 It can exhibit ionic conductivity of S / cm or more.

[0072] 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 may include one or more of these. In addition, the polymer electrolyte may include, as a polymer resin, a branched copolymer in which an amorphous polymer such as PMMA, polycarbonate, polysiloxane (PDMS) and / or phosphazene is copolymerized as a comonomer in a polyethylene oxide (PEO) main chain, a comb-like polymer, and a cross-linked polymer resin, and may include one or more of these.

[0073] In the above polymer solid electrolyte, the above-mentioned lithium salt is an ionizable lithium salt, Li + X - It can be expressed as . There is no particular limitation on the anion of these lithium salts, but 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:

[0074] The above oxide-based solid electrolyte may contain oxygen (O) and have the ionic conductivity of a metal belonging to Group 1 or Group 2 of the periodic table. For example, an LLTO-based compound, Li6La2CaTa2O 12 , Li6La2ANb2O 12 (A is Ca or Sr), Li2Nd3TeSbO 12 , Li3BO 2.5 N 0.5 , Li9SiAlO8, LAGP compounds, LATP compounds, Li1 +x Ti 2-x Al x Si y (PO4) 3-y (where, 0≤x≤1, 0≤y≤1), LiAl x Zr 2-x (PO4)3(where, 0≤x≤1, 0≤y≤1), LiTi x Zr 2-x (PO4)3 (wherein, 0≤x≤1, 0≤y≤1), may include at least one selected from among LISICON compounds, LIPON compounds, perovskite compounds, NASICON compounds, and LLZO compounds.

[0075] In addition, the solid electrolyte layer may additionally include a binder, and the type thereof is not particularly limited as long as it is used in the art.

[0076] 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.

[0077]

[0078] All-solid-state battery manufacturing method

[0079] The present invention relates to a method for manufacturing an all-solid-state battery.

[0080] (1) A step of preparing a composition for forming a negative electrode active material layer by mixing a carbon-based material, a binder, and a solvent;

[0081] (2) A step of forming a negative electrode active material layer by applying and drying the composition for forming the negative electrode active material layer on a negative electrode current collector;

[0082] (3) A step of manufacturing a negative electrode by pressurizing the negative electrode active material layer;

[0083] (4) A step of preparing a composition for forming a solid electrolyte layer by mixing a solid electrolyte, a binder, and a solvent;

[0084] (5) A step of manufacturing a solid electrolyte layer by applying and drying the composition for forming the solid electrolyte layer on the negative electrode active material layer; and

[0085] (6) A step of laminating a positive electrode on the solid electrolyte layer may be included, and the all-solid-state battery manufactured through the step may be the all-solid-state battery of the present invention described above.

[0086]

[0087] The above step (1) is a step for preparing a composition for forming a negative electrode active material layer, and the composition for forming a negative electrode active material layer is in the form of a slurry and may include a carbon-based material, a binder, and a solvent, and may additionally include a metal. The carbon-based material, the binder, and the metal are as described above. The type of the solvent is not particularly limited as long as it can disperse the carbon-based material, the binder, and the metal.

[0088] The above carbon-based material and binder can be mixed in a weight ratio of 95:5 to 90:10.

[0089] The above step (2) is a step of forming a negative electrode active material layer by applying and drying the composition for forming a negative electrode active material layer in the form of a slurry prepared in the above step (1) onto a negative electrode current collector, and the negative electrode current collector is as described above.

[0090] The above-mentioned coating method for coating the composition for forming a negative electrode active material layer on a negative electrode current collector may include a method of distributing the composition for forming a negative electrode active material layer on a negative electrode current collector and then uniformly dispersing it using a doctor blade or the like, die casting, comma coating, screen printing, or the like. At this time, the final thickness of the coating can be controlled by adjusting the concentration of the composition for forming a negative electrode active material layer, the number of coatings, etc.

[0091] The above drying is a process for removing the solvent and moisture within the composition for drying the composition for forming the negative electrode active material layer applied to the negative electrode current collector, and may vary depending on the solvent used. For example, it may be 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 a range of 30 seconds to 24 hours.

[0092] The step (3) above is a step of pressurizing the negative active material layer formed in the step (2), and the pressurization may be 30 to 500 MPa. By pressurizing the negative active material layer, the porosity and the average pore diameter of the negative active material layer can be reduced. By pressurizing in the above range, the negative active material layer of the present invention can have a porosity of 15 to 40%, and the average pore diameter can be less than 0.5 to 0.7 μm. Accordingly, as described above, the penetration of the fine particle solid electrolyte into the pores of the negative active material layer can be reduced, thereby reducing the irreversible capacity of the all-solid-state battery and improving the life characteristics. If the negative active material layer is not pressurized or is pressurized at less than 30 MPa, the porosity of the negative active material layer is not reduced, and the average particle size of the solid electrolyte existing at the interface between the negative active material layer and the solid electrolyte layer is less than 1 μm, and accordingly, the effect of improving the life characteristics of the all-solid-state battery cannot be obtained. Additionally, if the pressure exceeds 500 MPa, the cathode may be damaged due to the strong pressure.

[0093] The above step (4) is a step for preparing a composition for forming a solid electrolyte layer, and the composition for forming a solid electrolyte layer includes a solid electrolyte, a binder, and a solvent, and may be in the form of a slurry. The solid electrolyte and the binder are as described above. The solvent can disperse the solid electrolyte and the binder, and may have a dielectric constant of 0.5 to 10. Examples of the solvent that can be used include xylene, hexane, benzene, anisole, isobutyl isobutyrate, toluene, and butyl butyrate.

[0094] The above solid electrolyte and binder can be mixed in a weight ratio of 98:2 to 90:10.

[0095] The above step (5) is a step of forming a solid electrolyte layer by applying and drying the composition for forming a solid electrolyte layer manufactured in the above step (4) on a negative electrode active material layer, and the applying and drying may be the same as the applying and drying of the above-described step (2).

[0096] The above step (6) is a step of laminating an anode on a solid electrolyte layer.

[0097] The above positive electrode is manufactured by applying and drying a composition for forming a positive electrode active material layer on a positive electrode current collector. The composition for forming a positive electrode active material layer may include a binder or a conductive agent in addition to the positive electrode active material. The positive electrode current collector, positive electrode active material, binder, and conductive agent are as described above. In addition, the composition for forming a positive electrode active material layer is in the form of a slurry, and the type of solvent is not particularly limited as long as it can disperse the positive electrode active material, binder, and conductive agent.

[0098] The composition for forming the positive electrode active material layer may be applied and dried on a positive electrode current collector to manufacture the positive electrode, and the application and drying may be the same as the application and drying in step (2) described above.

[0099] 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.

[0100]

[0101] 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.

[0102]

[0103] <All-solid-state battery manufacturing>

[0104] Example 1.

[0105] A slurry-type composition for forming a negative electrode active material layer was prepared by dispersing a negative electrode active material (carbon black), a binder (polyvinylidene fluoride), and silver (Ag) in methyl pyrrolidone. The composition for forming a negative electrode active material layer was applied onto a SUS negative electrode current collector, and vacuum drying was performed at a temperature of 100°C for 10 hours to form a negative electrode active material layer.

[0106] The above negative active material layer was pressurized to 300 MPa using CIP. The porosity of the negative active material layer was 25%, and the average pore diameter was 0.5 μm.

[0107] A slurry-type solid electrolyte layer forming composition was prepared by dispersing a solid electrolyte (agrodite, Li6PS5Cl) and a binder (nitrile butadiene rubber) in butyrate. At this time, the average particle size (D50) of the solid electrolyte was 2.66 μm, D10 was 0.79 μm, D90 was 6.42 μm, and D99 was 10.9 μm.

[0108] The above composition for forming a solid electrolyte layer was applied onto a negative electrode active material layer using a bar coater, and then vacuum dried at a temperature of 70°C for 5 hours to form a solid electrolyte layer.

[0109] A slurry composition for forming a positive electrode active material layer was prepared by dispersing a positive electrode active material (NCM 811), a conductive agent (carbon fiber), a solid electrolyte (Li6PS5Cl), and a binder (polytetrafluoroethylene) in a solvent (butyrate). The composition for forming a positive electrode active material layer was applied to a positive electrode current collector and then dried to prepare a positive electrode including a positive electrode active material layer.

[0110] The above positive electrode was laminated on a solid electrolyte layer to manufacture an all-solid-state battery.

[0111]

[0112] Comparative Example 1.

[0113] An all-solid-state battery was manufactured in the same manner as in Example 1, except that the process of pressurizing the negative electrode active material layer was not performed.

[0114] The porosity of the negative active material layer of the above all-solid-state battery was 45%, and the average pore diameter was 0.7 μm.

[0115]

[0116] Experimental Example 1. Measurement of the average particle size (D50) of the solid electrolyte present at the interface between the negative electrode active material layer and the solid electrolyte layer.

[0117] In the all-solid-state batteries of Example 1 and Comparative Example 1, the average particle size (D50) of the solid electrolyte present at the interface between the negative electrode active material layer and the solid electrolyte layer was measured.

[0118] Fig. 1 is a cross-sectional photograph of an all-solid-state battery of Example 1, and Fig. 2 is a cross-sectional photograph of an all-solid-state battery of Comparative Example 1. The particle size was measured using the imageJ program.

[0119] The average particle size of the solid electrolyte included in the composition for forming a solid electrolyte layer was 2.66 μm, D10 was 0.79 μm, and the average particle size (D50) of the solid electrolyte present at the interface was measured to be 1.38 μm for Example 1 and 0.83 μm for Comparative Example 1.

[0120] Since the fine particles of solid electrolyte penetrate into the pores of the negative electrode active material layer, the average particle size of the solid electrolyte present at the interface is smaller than the average particle size of the solid electrolyte included in the composition for forming the solid electrolyte layer. The porosity of the negative electrode active material layer of Example 1 is lower than that of the negative electrode active material layer of Comparative Example 1, and the average diameter of the pores is smaller, so Example 1 showed a result in which the average particle size of the solid electrolyte present at the interface was larger than that of Comparative Example 1.

[0121]

[0122] Experimental Example 2. Measurement of the life characteristics of an all-solid-state battery.

[0123] The life characteristics of the all-solid-state batteries of Example 1 and Comparative Example 1 were measured.

[0124] The life characteristics were measured by charging the all-solid-state battery to 4.25 V at 0.33 C in CCCV mode at a temperature of 60°C and discharging it to 3.0 V with a constant current for 50 charge and discharge cycles, and the capacity retention rate was measured.

[0125] The results are shown in Figure 3.

[0126] In the all-solid-state battery of Example 1, the average particle size (D50) of the solid electrolyte existing at the interface between the negative active material layer and the solid electrolyte layer is larger than that of Comparative Example 1. That is, the porosity of the negative active material layer of Example 1 is lower than that of Comparative Example 1, and the average diameter of the pores is smaller, so that the solid electrolyte penetrating into the pores is less than that of Comparative Example 1. Accordingly, the all-solid-state battery of Example 1 showed excellent life characteristics. On the other hand, in the all-solid-state battery of Comparative Example 1, since the solid electrolyte penetrating into the pores is more than that of Example 1, the side reactions and irreversible capacity of the negative active material and the solid electrolyte increased, and the life characteristics deteriorated.

[0127] Accordingly, it can be seen that the all-solid-state battery of the present invention can improve the life characteristics of the all-solid-state battery by reducing the solid electrolyte penetrating into the pores of the negative electrode active material layer since the average particle size (D50) of the solid electrolyte present at the interface between the negative electrode active material layer and the solid electrolyte layer is 1 to 3 μm.

Claims

1. A positive electrode including a positive electrode active material layer; a negative electrode including a negative electrode active material layer; and a solid electrolyte layer including a solid electrolyte interposed between the positive electrode active material layer and the negative electrode active material layer; The above negative active material layer includes a carbon-based material, An all-solid-state battery, wherein the average particle size of the solid electrolyte present at the interface between the negative active material layer and the solid electrolyte layer is 1 to 3 μm.

2. In paragraph 1, An all-solid-state battery, wherein the porosity of the negative active material layer is 15 to 40%.

3. In paragraph 2, An all-solid-state battery, wherein the average diameter of the pores of the negative active material layer is less than 0.5 to 0.7 μm.

4. In paragraph 1, An all-solid-state battery, wherein the carbon-based material comprises at least one selected from the group consisting of 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 fluorinated carbon.

5. In paragraph 1, The above negative active material layer additionally includes a metal, An all-solid-state battery, wherein the metal comprises at least one selected from the group consisting of nickel, copper, silver, gold, platinum, aluminum, zinc, palladium, and bismuth.

6. In paragraph 1, An all-solid-state battery, wherein the average particle size of the solid electrolyte is 2 to 4 μm.

7. In paragraph 1, An all-solid-state battery, 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.

8. In paragraph 7, An all-solid-state battery, wherein the solid electrolyte comprises a sulfide-based solid electrolyte. 9.(1) A step of preparing a composition for forming a negative electrode active material layer by mixing a carbon-based material, a binder, and a solvent; (2) A step of forming a negative electrode active material layer by applying and drying the composition for forming the negative electrode active material layer on a negative electrode current collector; (3) A step of manufacturing a negative electrode by pressurizing the negative electrode active material layer; (4) A step of preparing a composition for forming a solid electrolyte layer by mixing a solid electrolyte, a binder, and a solvent; (5) A step of manufacturing a solid electrolyte layer by applying and drying the composition for forming the solid electrolyte layer on the negative electrode active material layer; and (6) A method for manufacturing an all-solid-state battery according to claim 1, comprising the step of laminating a positive electrode on the solid electrolyte layer.

10. In paragraph 9, A method for manufacturing an all-solid-state battery, wherein the pressure in step (3) is 30 to 500 MPa.

11. In paragraph 9, A method for manufacturing an all-solid-state battery, wherein the positive electrode is manufactured by applying and drying a composition for forming a positive electrode active material layer, which includes a positive electrode active material, a binder, and a solvent, to a positive electrode current collector.

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