Positive electrode for all-solid-state battery and all-solid-state battery including the same

Abstract

The present invention relates to a cathode for an all-solid-state battery and an all-solid-state battery including the same. More specifically, the cathode active material layer includes a cathode active material, a sulfide-based solid electrolyte, a conductive material, and a porous carbon additive. The particle size of the porous carbon additive is between the particle size of the cathode active material and the particle size of the sulfide-based solid electrolyte, thereby increasing the interface between the cathode active material and the sulfide-based solid electrolyte and reducing the porosity of the entire cathode. This maintains the conductivity of the cathode and increases the energy density of the cell without degrading cell performance.

Description

[Technical Field]

[0001] The present invention claims the benefit of priority based on Korean Patent Application No. 10-2023-0094993, filed on July 21, 2023, and all contents disclosed in the documents of this Korean patent application are incorporated herein by reference.

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

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

[0004] Academia and industry are currently conducting continuous research into 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] Among the various next-generation batteries, all-solid-state batteries are those that replace the liquid electrolyte used in conventional lithium secondary batteries with a solid electrolyte. Because they do not use flammable solvents, they are completely free of fires and explosions caused by decomposition reactions of conventional electrolytes, significantly improving safety. Furthermore, among all-solid-state batteries, technological development is progressing on sulfide-based all-solid-state batteries, which have high ionic conductivity and can theoretically achieve high energy densities of over 900 Wh / L. Here, sulfide-based all-solid-state batteries refer to all-solid-state batteries that contain a sulfide-based solid electrolyte.

[0006] In all-solid-state battery systems, lithium ion conduction is not achieved by the liquid electrolyte found in conventional lithium-ion batteries (LIBs). Therefore, when manufacturing cathodes for sulfide-based all-solid-state batteries, small sulfide-based solid electrolyte particles must be added to the cathode to increase the contact interface between the cathode active material and the sulfide-based solid electrolyte particles, thereby enhancing lithium ion conduction. Furthermore, to improve energy density, it is necessary to promote physical contact between the cathode active material, sulfide-based solid electrolyte particles, and other battery elements within the cathode, thereby reducing the porosity of the cathode after rolling, which must be maintained during charging and discharging.

[0007] For this reason, there is a continuing need for technological development that can further reduce the porosity in the positive electrode of a sulfide-based all-solid-state battery and improve the performance of the all-solid-state battery. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Korean Patent Publication No. 2016-0118597 Summary of the Invention [Problem to be solved by the invention]

[0009] The present inventors have conducted extensive research to solve the above problems, and as a result, have found that when a cathode active material layer for a cathode of an all-solid-state battery is manufactured using a cathode active material, a sulfide-based solid electrolyte, a conductive material, and a porous carbon additive, the particle size of the porous carbon additive is between that of the cathode active material and that of the sulfide-based solid electrolyte so as to fill voids between the particles of the cathode active material and the sulfide-based solid electrolyte, and the specific surface area of ​​the porous carbon additive is limited to a certain level or less, the porosity of the cathode active material layer is reduced, thereby improving the energy density of the all-solid-state battery.

[0010] Therefore, an object of the present invention is to provide a positive electrode for an all-solid-state battery having reduced porosity.

[0011] Another object of the present invention is to provide an all-solid-state battery including the reduced porosity positive electrode for the all-solid-state battery. [Means for solving the problem]

[0012] In order to achieve the above object, the present invention provides a positive electrode for an all-solid-state battery, comprising a positive electrode active material, a sulfide-based solid electrolyte, a conductive material, and a porous carbon additive, the particle size of the porous carbon additive is between the particle size of the positive electrode active material and the particle size of the sulfide-based solid electrolyte; The porous carbon additive has a BET specific surface area of ​​100 m 2 The present invention provides a positive electrode for an all-solid-state battery, characterized by a low specific surface area porous carbon additive of 0.1g / g or less.

[0013] The present invention also provides a porous carbon additive having a BET specific surface area of ​​70 m 2 / g or less.

[0014] The present invention also provides a positive electrode for an all-solid-state battery, wherein the particle size (D50) of the porous carbon additive is 1.0 μm to 4.0 μm.

[0015] The present invention also provides a positive electrode for an all-solid-state battery, wherein the porous carbon additive has a bulk density of 0.18 g / cc or more.

[0016] The present invention also provides a positive electrode for an all-solid-state battery, wherein the porous carbon additive has a powder resistivity of 0.05 Ω·cm or less.

[0017] The present invention also provides a positive electrode for an all-solid-state battery, wherein the particle size (D50) of the positive electrode active material is 3.0 μm to 8.0 μm.

[0018] The present invention also provides a positive electrode for an all-solid-state battery, wherein the particle size (D50) of the sulfide-based solid electrolyte is 0.1 μm to 1.5 μm.

[0019] The present invention also provides a positive electrode for an all-solid-state battery, wherein the positive electrode is in the form of a pellet containing a positive electrode active material, a sulfide-based solid electrolyte, a conductive material, and a porous carbon additive.

[0020] The present invention also provides a method for manufacturing a battery, the method comprising the steps of: providing a positive electrode current collector; and forming a positive electrode active material layer on one surface of the positive electrode current collector. The positive electrode active material layer includes a positive electrode active material, a sulfide-based solid electrolyte, a conductive material, a binder, and a porous carbon additive.

[0021] The present invention also provides a positive electrode for an all-solid-state battery, wherein the binder comprises at least one selected from the group consisting of polytetrafluoroethylene (PTFE), polyethylene, polypropylene, ethylene / propylene copolymer, polybutadiene, polyethylene oxide, chlorosulfonated polyethylene, polyvinylpyrrolidone, polyvinylpyridine, polyvinyl alcohol, polyvinyl acetate, polyepichlorohydrin, polyphosphazene, polyacrylonitrile, polystyrene, latex, acrylic resin, phenolic resin, epoxy resin, carboxymethyl cellulose, hydroxypropyl cellulose, cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate, cyanoethyl cellulose, cyanoethyl sucrose, polyester, polyamide, polyether, polyimide, polycarboxylate, polycarboxylic acid, polyacrylic acid, polyacrylate, lithium polyacrylate, polymethacrylic acid, polymethacrylate, polyacrylamide, polyurethane, polyvinylidene fluoride, and poly(vinylidene fluoride)-hexafluoroprofen.

[0022] The present invention also provides a positive electrode for an all-solid-state battery, wherein the conductive material is one or more linear conductive materials selected from the group consisting of carbon nanotubes (CNTs) and carbon nanofibers (CNFs).

[0023] The present invention also provides a positive electrode for an all-solid-state battery, wherein the porous carbon additive is at least one selected from the group consisting of soft carbon and hard carbon.

[0024] The present invention also provides a positive electrode for an all-solid-state battery, wherein the porous carbon additive is at least one selected from the group consisting of activated carbon and carbon black.

[0025] The present invention also provides a positive electrode for an all-solid-state battery, wherein the positive electrode has a porosity of 5 vol % to 19 vol %.

[0026] The present invention also provides a cathode active material, the cathode active material being contained in an amount of 55 to 90 wt % based on the total weight of the cathode, The sulfide-based solid electrolyte is contained in an amount of 10 to 50 wt % based on the total weight of the positive electrode, The conductive material is contained in an amount of 0.05 to 10 wt % based on the total weight of the positive electrode, The porous carbon additive is contained in an amount of 0.1 to 3 wt % based on the total weight of the positive electrode.

[0027] The present invention also provides an all-solid-state battery comprising the positive electrode, the negative electrode, and a sulfide-based solid electrolyte layer interposed therebetween. [Effects of the Invention]

[0028] According to the positive electrode for an all-solid-state battery of the present invention, the porous carbon additive fills the gaps between the particles of the positive electrode active material and the sulfide-based solid electrolyte, thereby reducing the porosity of the positive electrode, thereby improving the energy density of the all-solid-state battery. Furthermore, by using a linear conductive material as the conductive material for the positive electrode for an all-solid-state battery, the conductivity of the positive electrode is maintained, thereby achieving the effect of improving the energy density without deteriorating the performance of the all-solid-state battery. [Brief explanation of the drawings]

[0029] [Figure 1] 1 is a scanning electron microscope photograph of the side surface of the positive electrodes produced in Example 2, Comparative Example 3, and Comparative Example 4. DETAILED DESCRIPTION OF THE INVENTION

[0030] The present invention will now be described in further detail to aid in its understanding.

[0031] 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 explain his / her invention.

[0032] In this specification, in order to distinguish between positive electrodes manufactured depending on whether or not the positive electrode active material layer contains a binder, a positive electrode that does not contain a binder may be referred to as a "composite positive electrode," and a positive electrode that contains a binder may be referred to as a "positive electrode."

[0033] Positive electrode for all-solid-state batteries The present invention relates to a positive electrode for an all-solid-state battery.

[0034] The positive electrode for an all-solid-state battery according to the present invention includes a positive electrode active material, a sulfide-based solid electrolyte, a conductive material, and a porous carbon additive.

[0035] In one embodiment of the present invention, the positive electrode may be in the form of a pellet. The pellet-shaped positive electrode may be used without a current collector, or the pellet may be disposed on a current collector to form the positive electrode. The pellet may be formed by compressing a composite powder containing a positive electrode active material, a sulfide-based solid electrolyte, a conductive material, and a porous carbon additive. Since the pellet does not contain a binder, it is possible to eliminate resistance that may be caused by the binder.

[0036] In another embodiment of the present invention, the positive electrode may include a positive electrode current collector and a positive electrode active material layer formed on one surface of the positive electrode current collector. The positive electrode active material layer may include the positive electrode active material, a sulfide-based solid electrolyte, a conductive material, a binder, and a porous carbon additive.

[0037] The particle size of the porous carbon additive is between the particle size of the positive electrode active material and the particle size of the sulfide-based solid electrolyte, and the porous carbon additive has a BET specific surface area of ​​100 m 2 / g or less. The conductive material may be a linear conductive material in consideration of the specific surface area. In this specification, a positive electrode that does not contain a binder may correspond to a composite positive electrode.

[0038] In the positive electrode for an all-solid-state battery according to the present invention, voids are formed due to the difference in particle size between the positive electrode active material and the sulfide-based solid electrolyte particles, and the voids are filled with the porous carbon additive, thereby reducing the porosity of the positive electrode and improving the energy density. The particle size (D50) of the porous carbon additive may be larger than the particle size (D50) of the sulfide-based solid electrolyte and smaller than the particle size (D50) of the positive electrode active material, thereby filling the voids with the porous carbon additive.

[0039] In one embodiment of the present invention, the BET specific surface area of ​​the porous carbon additive is 100 m 2 Specifically, the specific surface area of ​​the porous carbon additive may be a BET specific surface area of ​​100 m 2 / g or less, 90m 2 / g or less, 80m 2 / g or less, 70m 2 / g or less, 60m 2 / g or less, 50m 2 / g or less, 40m 2 / g or less, or 30m 2 / g or less. 2 If the BET specific surface area is more than 5 m / g, the contact interface between the porous carbon additive having a high specific surface area and the sulfide-based all-solid electrolyte for the positive electrode increases, which may increase the electrolyte decomposition reaction and reduce the ionic conductivity of the positive electrode itself. 2 / g or more.

[0040] The porous carbon additive has a low specific surface area as defined above and may be called macroporous carbon.

[0041] The particle size (D50) of the porous carbon additive may be 1.0 μm to 4.0 μm. Specifically, the particle size (D50) of the porous carbon additive may be 1.0 μm or more, 1.5 μm or more, or 2.0 μm or more, or 3.0 μm or less, 3.5 μm or less, or 4.0 μm or less. If the particle size (D50) of the porous carbon additive is less than 1.0 μm, the particles may be too small and the porous carbon additive may be adsorbed only on the surface of the positive electrode active material rather than filling voids formed by the difference in particle size between the positive electrode active material and the sulfide-based solid electrolyte particles. If the particle size (D50) of the porous carbon additive is more than 4.0 μm, it may be difficult to fill voids formed by the difference in particle size between the positive electrode active material and the sulfide-based solid electrolyte particles, and the effect of reducing the porosity of the positive electrode may be negligible.

[0042] The particle size (D50) can be measured by putting the porous carbon additive into a particle size analyzer (Mastersizer 3000, Malvern).

[0043] The porous carbon additive may have a bulk density of 0.18 g / cc or more.

[0044] Specifically, the bulk density may be 0.18 g / cc or more, 0.19 g / cc or more, or 0.20 g / cc or more. If the bulk density is less than 0.18 g / cc, the density of the porous carbon additive itself may be low, which may reduce the density of the entire positive electrode. The upper limit of the bulk density is not particularly limited, but may be 0.5 g / cc or less.

[0045] The bulk density can be measured using a density meter in accordance with ASTM D 1895 method.

[0046] The porous carbon additive may have a powder resistivity of 0.05 Ω·cm or less.

[0047] Specifically, the powder resistivity may be 0.05 Ω·cm or less, 0.04 Ω·cm or less, or 0.03 Ω·cm or less. If the powder resistivity exceeds 0.05 Ω·cm, the overall resistance of the positive electrode may increase if the porous carbon additive is contained in the positive electrode at a specific ratio or more. The lower limit of the powder resistivity is not particularly limited, but may be 0.005 Ω·cm or more. If the powder resistivity is excessively low, electron transfer between the porous carbon additive and the sulfide-based all-solid-state electrolyte in contact with the additive becomes active, which may cause the sulfide-based all-solid-state electrolyte to decompose.

[0048] The powder resistance can be measured using a powder resistance meter (HPRM-FA2, Hantech). After a lower punch is attached to the body of a powder resistor mold, a conductive material measurement sample of known weight is weighed, and an upper punch is attached and placed in the powder resistance meter. The powder resistance meter is then operated to apply pressure from 0 to 2000 kgf in 400 kgf increments, and the final powder resistance can be observed at 2000 kgf (196 MPa).

[0049] The porous carbon additive may include at least one selected from the group consisting of soft carbon and hard carbon, but is not limited thereto as long as it is a particulate carbon material. For example, the porous carbon additive may be at least one selected from the group consisting of activated carbon and carbon black.

[0050] The porous carbon additive may be included in an amount of 0.1 to 3 wt % based on the total weight of the positive electrode active material layer. Specifically, the content of the porous carbon additive may be 0.1 wt %, 0.2 wt % or more, 0.3 wt % or more, 0.4 wt % or more, or 0.5 wt % or more, or 1.2 wt % or less, 1.5 wt % or less, 2.0 wt % or less, 2.5 wt % or less, or 3.0 wt % or less. If the content of the porous carbon additive is less than 0.1 wt %, the effect of improving energy density due to the reduced porosity caused by the use of the porous carbon additive may be negligible, while if it exceeds 3 wt %, mass transfer resistance may be increased.

[0051] In one embodiment of the present invention, the particle size (D50) of the positive electrode active material may be 3.0 μm to 8.0 μm.

[0052] Specifically, the particle size (D50) of the positive electrode active material may be 3.0 μm or more, 3.5 μm or more, or 4.0 μm or more, or 6.0 μm or less, 6.5 μm or less, 7.0 μm or less, 7.5 μm or less, or 8.0 μm or less. If the particle size (D50) of the positive electrode active material is less than 3.0 μm, even if the positive electrode active material and the all-solid-state electrolyte are dispersed at the same weight ratio, the particle size of the positive electrode active material may be small and the dispersibility may be reduced. If the particle size (D50) exceeds 7.0 μm, excessively large voids may be formed in the positive electrode active material layer, which may reduce the performance of the all-solid-state battery.

[0053] The particle size (D50) can be measured by putting the positive electrode active material powder into a particle size analyzer (Mastersizer 3000, Malvern).

[0054] The positive electrode active material is not particularly limited as long as it is a material capable of reversibly absorbing and releasing lithium ions. For example, lithium cobalt oxide (LiCoO), lithium nickel oxide (LiNiO), Li[Ni x Co y Mn z M v ]O2 (wherein M is one or more elements selected from the group consisting of Al, Ga, and In; 0.3≦x<1.0, 0≦y, z≦0.5, 0≦v≦0.1, and x+y+z+v=1), Li (Li a M b-a-b’ M' b’ )O 2-c A c (wherein 0≦a≦0.2, 0.6≦b≦1, 0≦b′≦0.2, 0≦c≦0.2; M comprises Mn and one or more elements selected from the group consisting of Ni, Co, Fe, Cr, V, Cu, Zn, and Ti; M′ is one or more elements selected from the group consisting of Al, Mg, and B; and A is one or more elements selected from the group consisting of P, F, S, and N); layered compounds or compounds substituted with one or more transition metals such as those represented by the formula Li 1+y Mn 2-y Lithium manganese oxides such as LiMnO4 (where y is 0 to 0.33), LiMnO3, LiMn2O3, and LiMnO2; lithium copper oxide (Li2CuO2); vanadium oxides such as LiV3O8, LiFe3O4, V2O5, and Cu2V2O7; and the chemical formula LiNi 1-y Ni-site lithium nickel oxide represented by MyO2 (where M=Co, Mn, Al, Cu, Fe, Mg, B, or Ga, and y is 0.01 to 0.3); chemical formula: LiMn 2-y M yExamples of suitable lithium manganese composite oxides include, but are not limited to, lithium manganese composite oxides represented by LiMnO2 (where M is Co, Ni, Fe, Cr, Zn, or Ta, and y is 0.01 to 0.1) or Li2Mn3MO8 (where M is Fe, Co, Ni, Cu, or Zn); LiMn2O4, in which part of the Li in the chemical formula is substituted with an alkaline earth metal ion; disulfide compounds; and Fe2(MoO4)3.

[0055] The positive electrode active material may be included in an amount of 55 to 90 wt % based on the total weight of the positive electrode active material layer. Specifically, the content of the positive electrode active material may be 55 wt %, 60 wt % or more, or 65 wt % or more, or 83 wt % or less, 85 wt % or less, or 90 wt % or less. If the content of the positive electrode active material is less than 55 wt %, battery performance may be reduced, and if it exceeds 90 wt %, mass transfer resistance may be increased.

[0056] In one embodiment of the present invention, the particle size (D50) of the sulfide-based solid electrolyte may be 0.1 μm to 1.5 μm.

[0057] Specifically, the particle size (D50) of the sulfide-based solid electrolyte may be 0.1 μm or more, 0.3 μm or more, or 0.5 μm or more, or 0.9 μm or less, 1.0 μm or less, 1.2 μm or less, or 1.5 μm or less. If the particle size (D50) of the sulfide-based solid electrolyte is less than 0.1 μm, the ultrafine particles of the all-solid electrolyte may not be sufficiently dispersed in the positive electrode layer and may aggregate. If the particle size (D50) exceeds 1.5 μm, dispersion is somewhat easier, but the contact surface with the positive electrode active material particles is reduced, which may increase the positive electrode porosity.

[0058] The sulfide-based solid electrolyte may include at least one selected from the group consisting of LiPSX (X = Cl, Br, or I), LiGePS, and LiPS. However, the sulfide-based solid electrolyte is not limited thereto, and a wide variety of sulfide-based solid electrolytes commonly used in the art may be used.

[0059] The sulfide-based solid electrolyte may be included in an amount of 10 to 50 wt % based on the total weight of the positive electrode active material layer. Specifically, the content of the sulfide-based solid electrolyte may be 10 wt % or more, 20 wt % or more, or 30 wt % or more, or 40 wt % or less, 45 wt % or less, or 50 wt % or less. If the content of the positive electrode active material is less than 10 wt %, it may be insufficient to fill voids formed in the positive electrode active material layer, making it difficult to reduce the porosity of the positive electrode active material. If the content exceeds 50 wt %, the content of the positive electrode active material and the conductive material may be relatively reduced, resulting in reduced battery performance.

[0060] In one embodiment of the present invention, the conductive material may be a linear conductive material, and the linear conductive material may be one or more selected from the group consisting of carbon nanotubes (CNT) and carbon nanofibers (CNF). The linear conductive material can improve electrical conductivity due to its geometric characteristics.

[0061] The conductive material may be included in an amount of 0.05 to 10 wt % based on the total weight of the positive electrode active material layer. Specifically, the content of the conductive material may be 0.05 wt % or more, 0.1 wt % or more, 0.5 wt % or more, 1 wt % or more, 2 wt % or more, or 3 wt % or more, or 5 wt % or less, 7 wt % or less, or 10 wt % or less. If the content of the conductive material is less than 0.05 wt %, the electrical conductivity of the positive electrode may be reduced. If the content of the conductive material is more than 10 wt %, the content of the positive electrode active material and the sulfide-based solid electrolyte may be relatively reduced, resulting in reduced battery performance.

[0062] In one embodiment of the present invention, the positive electrode active material layer may further include a binder. The binder may be included to promote bonding between materials included in the positive electrode active material layer and between the positive electrode active material layer and the positive electrode current collector. The binder may promote bonding between materials included in the positive electrode active material layer and further reduce the positive electrode porosity.

[0063] The binder may be a fibrous binder. The binder may be fibrous during the mixing process in manufacturing the positive electrode, and may be contained in the positive electrode active material layer in a fibrous form. Therefore, it is preferable that the physical properties of the binder are easily deformable.

[0064] The binder may also include one or more selected from the group consisting of polytetrafluoroethylene (PTFE), polyethylene, polypropylene, ethylene / propylene copolymer, polybutadiene, polyethylene oxide, chlorosulfonated polyethylene, polyvinylpyrrolidone, polyvinylpyridine, polyvinyl alcohol, polyvinyl acetate, polyepichlorohydrin, polyphosphazene, polyacrylonitrile, polystyrene, latex, acrylic resin, phenolic resin, epoxy resin, carboxymethyl cellulose, hydroxypropyl cellulose, cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate, cyanoethyl cellulose, cyanoethyl cellulose, polyester, polyamide, polyether, polyimide, polycarboxylate, polycarboxylic acid, polyacrylic acid, polyacrylate, lithium polyacrylate, polymethacrylic acid, polymethacrylate, polyacrylamide, polyurethane, polyvinylidene fluoride, and poly(vinylidene fluoride)-hexafluoroprofen. Preferably, the binder may include polytetrafluoroethylene (PTFE).

[0065] The binder may be included in an amount of 0.1 to 3 wt % based on the total weight of the positive electrode active material layer. Specifically, the binder content may be 0.1 wt % or more, 0.5 wt % or more, or 0.8 wt % or more, or 1.5 wt % or less, 2 wt % or less, or 3 wt % or less. If the binder content is less than 0.1 wt %, the effect of improving the bonding strength between materials contained in the positive electrode active material layer is insignificant, and an electrode sheet may not be properly formed. If the binder content exceeds 3 wt %, ionic conductivity or electrical conductivity may be reduced.

[0066] In one embodiment of the present invention, the porosity of the positive electrode active material layer may be 5 vol % to 19 vol %.

[0067] Specifically, the porosity may be 5 vol% or more, 8 vol% or more, 10 vol% or more, or 13 vol% or more, and may be 17 vol%, 18 vol% or less, or 19 vol% or less. The porosity is within an optimized range in consideration of performance such as the energy density of the battery, and if the porosity exceeds 19 vol%, the energy density of the battery may decrease.

[0068] In one embodiment of the present invention, the thickness of the positive electrode active material layer may be 100 μm to 300 μm, specifically, 100 μm or more, 110 μm or more, or 120 μm or more, or 200 μm or less, 250 μm or less, or 300 μm or less. However, the thickness of the positive electrode active material layer is not limited thereto, and the thickness may be adjusted to have an appropriate positive electrode loading depending on the performance improvement of various positive electrode elements contained in the positive electrode active material layer.

[0069] In one embodiment of the present invention, the positive electrode current collector supports the positive electrode active material layer and serves to transfer electrons between an external conductor and the positive electrode active material layer.

[0070] The positive electrode current collector is not particularly limited as long as it does not cause a chemical change in the all-solid-state battery and has high electronic conductivity. For example, the positive electrode current collector may be made of stainless steel, aluminum, nickel, titanium, palladium, baked carbon, stainless steel surface-treated with carbon, nickel, silver, or the like, or an aluminum-cadmium alloy.

[0071] The positive electrode current collector may have a finely textured surface or a three-dimensional porous structure to strengthen the bonding strength with the positive electrode active material layer, and may have various forms such as a film, sheet, foil, mesh, net, porous body, foam, or nonwoven fabric.

[0072] Method for manufacturing positive electrodes of all-solid-state batteries The present invention also relates to a method for manufacturing a positive electrode for an all-solid-state battery. Specific materials, properties, and contents of the positive electrode active material, sulfide-based solid electrolyte, conductive material, porous carbon additive, and binder used in the method for manufacturing a positive electrode for an all-solid-state battery according to the present invention are as described above.

[0073] In the present invention, the positive electrode can be distinguished depending on whether it contains a binder or not, and can be called a "composite positive electrode" when it does not contain a binder, and a "positive electrode" when it contains a binder.

[0074] In one embodiment of the present invention, a method for manufacturing a binderless composite positive electrode may include: (A1) mixing a positive electrode active material, a sulfide-based solid electrolyte, a conductive material, and a porous carbon additive; and (A2) forming the mixed powder obtained in step (A1) into a pellet shape. In this case, the pellet shape in step (A2) may be formed by pressing the mixed powder in a jig.

[0075] The composite positive electrode prepared as described above may be used in a pressure chamber cell. Since the composite positive electrode does not contain a binder, the resistance caused by the binder can be eliminated. Therefore, the composite positive electrode can be used to evaluate the performance of a pressure chamber cell in which the resistance factor is eliminated.

[0076] In one embodiment of the present invention, a method for producing a binder-containing positive electrode includes: (B1) mixing a positive electrode active material, a sulfide-based solid electrolyte, a conductive material, and a porous carbon additive binder; (B2) subjecting the mixed powder obtained in step (B1) to a calendaring process to form the mixed powder into a film; and (B3) attaching the film-like positive electrode active material layer obtained in step (B2) to a positive electrode current collector.

[0077] The mixing in step (B1) may be physical mixing, which may result in the binder being fibrous. During physical mixing, shear force causes the binder to rub against the particles in the mixed powder, resulting in physical deformation and fiberization. For example, PTFE, which has physical properties that allow for easy physical deformation, may be used as the binder. Furthermore, to facilitate physical deformation, mixing may be performed using a mortar, ball mill, or roll press.

[0078] In addition, in the step (B2), the mixed powder obtained in the step (B1) may be subjected to a calendaring process to be formed into a film.

[0079] The conditions for the calendering step may be appropriately controlled to allow the material to be formed into a film. For example, the calendering step may be performed at a temperature of 50°C to 200°C for 5 to 50 loops. However, the calendering step conditions, such as temperature, pressure, and number of loops, may be any conditions used in electrode manufacturing processes commonly used in the battery field.

[0080] In addition, in the step (B3), the film-like positive electrode active material layer obtained in the step (B2) may be attached to a positive electrode current collector to produce a positive electrode for an all-solid-state battery.

[0081] all solid state battery The present invention also relates to an all-solid-state battery including a sulfide-based solid electrolyte layer.

[0082] The all-solid-state battery according to the present invention includes the positive electrode, the negative electrode, and a sulfide-based solid electrolyte layer interposed therebetween. The positive electrode is as described above.

[0083] In one embodiment of the present invention, the negative electrode may include a negative electrode active material layer, and the negative electrode active material layer may be formed on one surface of a negative electrode current collector.

[0084] The negative electrode active material layer may include a negative electrode active material, a conductive material, and a binder, or may be an anodeless layer.

[0085] In the negative electrode active material layer, the negative electrode active material is lithium (Li + The lithium ion-containing compound may include a material capable of reversible intercalation or deintercalation of lithium ions, a material capable of reversibly reacting with lithium ions to form a lithium-containing compound, lithium metal, or a lithium alloy.

[0086] The lithium ion (Li + The material capable of reversibly inserting or de-inserting lithium ions (Li) may be, for example, crystalline carbon, amorphous carbon, or a mixture thereof. +The material capable of reacting with lithium (Li) to reversibly form a lithium-containing compound may be, for example, tin oxide, titanium nitrate, or silicon. The lithium alloy may be, for example, an alloy of lithium (Li) and a metal selected from the group consisting of indium (In), sodium (Na), potassium (K), rubidium (Rb), cesium (Cs), francium (Fr), beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), radium (Ra), aluminum (Al), and tin (Sn).

[0087] Preferably, the negative electrode active material may be lithium metal or a lithium-indium alloy (Li-In), specifically, lithium metal, lithium and thin film, lithium-indium alloy thin film, or powder.

[0088] The negative electrode active material may be included in an amount of 40 to 80 wt % based on the total weight of the negative electrode active material layer. Specifically, the content of the negative electrode active material may be 40 wt % or more, or 50 wt % or more, or 70 wt % or less, or 80 wt % or less. If the content of the negative electrode active material is less than 40 wt %, the connectivity between the wet negative electrode active material layer and the dry negative electrode active material layer may be insufficient, and if it exceeds 80 wt %, the mass transfer resistance may be increased.

[0089] The binder may be a component that assists in binding the negative electrode active material to the conductive material and the like and in binding the negative electrode current collector, and may be selected from the group consisting of styrene-butadiene rubber, acrylated styrene-butadiene rubber, acrylonitrile copolymer, acrylonitrile-butadiene rubber, nitrile butadiene rubber, acrylonitrile-styrene-butadiene copolymer, acrylic rubber, butyl rubber, fluororubber, polytetrafluoroethylene, polyethylene, polypropylene, ethylene / propylene copolymer, polybutadiene, polyethylene oxide, chlorosulfonated polyethylene, polyvinylpyrrolidone, polyvinylpyridine, polyvinyl alcohol, polyvinyl acetate, polyepichlorohydrin, polyphosphazene, polyacrylic The binder may include one or more selected from the group consisting of lylonitrile, polystyrene, latex, acrylic resin, phenolic resin, epoxy resin, carboxymethyl cellulose, hydroxypropyl cellulose, cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate, cyanoethyl cellulose, cyanoethyl cellulose, polyester, polyamide, polyether, polyimide, polycarboxylate, polycarboxylic acid, polyacrylic acid, polyacrylate, lithium polyacrylate, polymethacrylic acid, polymethacrylate, polyacrylamide, polyurethane, polyvinylidene fluoride, and poly(vinylidene fluoride)-hexafluoropropene. Preferably, the binder may include polytetrafluoroethylene (PTFE).

[0090] The binder may be included in an amount of 0.5 wt % to 4 wt % based on the total weight of the negative electrode active material layer. Specifically, the binder content may be 0.5 wt % or more, 1 wt % or more, or 1.5 wt % or more, or 3 wt % or less, 3.5 wt % or less, or 4 wt % or less. If the binder content is less than 0.5 wt %, the adhesive strength between the positive electrode active material and the negative electrode current collector may be reduced. If the binder content exceeds 4 wt %, the adhesive strength is improved, but the content of the negative electrode active material may be reduced accordingly, which may reduce the battery capacity.

[0091] The conductive material is not particularly limited as long as it prevents side reactions in the internal environment of the all-solid-state battery, does not induce chemical changes in the battery, and has excellent electrical conductivity. Representative examples include graphite or conductive carbon, such as graphite (e.g., natural graphite, artificial graphite, etc.); carbon black (e.g., carbon black, acetylene black, ketjen black, denka black, thermal black, channel black, furnace black, lamp black, summer black, etc.); carbon-based materials with a graphene or graphite crystalline structure; conductive fibers (e.g., carbon fiber, metal fiber, etc.); carbon fluoride; metal powders (e.g., aluminum powder, nickel powder, etc.); conductive whiskers (e.g., zinc oxide, potassium titanate, etc.); conductive oxides (e.g., titanium oxide, etc.); and conductive polymers (e.g., polyphenylene derivatives). These may be used alone or in combination. Preferably, the conductive material may include vapor-grown carbon fiber (VGCF).

[0092] The conductive material may typically be included in an amount of 1 wt % to 5 wt % based on the total weight of the negative electrode active material layer. Specifically, the content of the conductive material may be 1 wt % or more, 1.5 wt % or more, or 2 wt % or more, and 4 wt % or less, 4.5 wt % or less, or 5 wt % or less. If the conductive material content is too low, such as less than 1 wt %, the effect of improving electrical conductivity may not be expected or the electrochemical properties of the battery may be degraded. If the conductive material content is too high, such as more than 5 wt %, the amount of negative electrode active material may be relatively small, resulting in reduced capacity and energy density. The method for incorporating the conductive material into the negative electrode is not particularly limited, and may be a conventional method known in the art, such as mixing or coating with the negative electrode active material.

[0093] The negative electrode current collector is not particularly limited as long as it does not cause a chemical change in the battery and is conductive, and may be, for example, copper, stainless steel, aluminum, nickel, titanium, baked carbon, copper or stainless steel surface-treated with carbon, nickel, titanium, silver, or the like, an aluminum-cadmium alloy, etc. Similarly to the positive electrode current collector, the negative electrode current collector may be in various forms such as a film, sheet, foil, net, porous material, foam, or nonwoven fabric having fine irregularities formed on the surface.

[0094] The method for manufacturing the negative electrode is not particularly limited, and the negative electrode may be manufactured by forming a negative electrode active material layer on a negative electrode current collector using a layer or film formation method commonly used in the art. For example, methods such as compression bonding, coating, and vapor deposition may be used. In addition, the negative electrode of the present invention also includes a case where a battery is assembled without a lithium thin film on the negative electrode current collector, and then a metallic lithium thin film is formed on the metal plate by initial charging.

[0095] The anode-free layer refers to an anode layer in which lithium metal or a lithium alloy, which serves as a lithium supply source among the anode active materials, is not present in the anode at the time of initial assembly of the battery, but lithium is deposited in the anode upon charging. A battery including the anode-free layer can also be called an anode-free battery.

[0096] In the anode-free battery, during charging and discharging of the battery, lithium ions released from the positive electrode migrate to the negative electrode to form a negative electrode active material layer. For example, during charging of the battery, lithium ions are released from the positive electrode active material and then migrate to the negative electrode side to become lithium metal composed purely of lithium, which may form a layered lithium metal layer on the negative electrode current collector, or may form a lithium metal structure of any shape other than a layer. The arbitrary shape may be, for example, a structure in which lithium metal is aggregated into particles.

[0097] In one embodiment of the present invention, the sulfide-based solid electrolyte included in the sulfide-based solid electrolyte layer may include one or more selected from the group consisting of LiPSX (X = Cl, Br, or I), LiGePS, and LiPS. However, the sulfide-based solid electrolyte is not limited thereto, and a wide variety of sulfide-based solid electrolytes commonly used in the art may be used.

[0098] Battery module The present invention also relates to a battery module including the all-solid-state battery as a unit cell, a battery pack including the battery module, and a device including the battery pack as a power source.

[0099] Specific examples of the device include, but are not limited to, power tools powered by a battery-powered motor; electric vehicles including electric vehicles (EVs), hybrid electric vehicles (HEVs), and plug-in hybrid electric vehicles (PHEVs); electric two-wheeled vehicles including electric bicycles (E-bikes) and electric scooters; electric golf carts; and power storage systems. Preferred embodiments of the present invention will be described below to aid in understanding the present invention. However, the following embodiments are merely illustrative of the present invention, and it will be apparent to those skilled in the art that various changes and modifications can be made within the scope and technical spirit of the present invention. It is to be understood that such changes and modifications are within the scope of the appended claims.

[0100] In the following examples and comparative examples, positive electrodes and all-solid-state batteries including the same were manufactured according to the compositions of the positive electrode active material layer and the physical properties of the raw materials as shown in Table 1 below.

[0101] [Table 1]

[0102] Example 1: Preparation of a composite positive electrode LiN as the positive electrode active material 0.8 Co 0.1 Mn 0.1 O2 (NCM 811), Li6PS5Cl as a sulfide-based solid electrolyte, carbon nanofiber (CNF) as a linear conductive material, and porous carbon additive (Heraeus, BET 60m 2 / g or less) to prepare a positive electrode as follows. Hereinafter, the porous carbon additive is referred to as low specific surface area porous carbon additive 1.

[0103] The positive electrode active material, sulfide-based solid electrolyte, conductive material, and porous carbon additive were mixed in a weight ratio of 60:35:4:1 and then powder mixed. Specifically, the positive electrode active material and sulfide-based solid electrolyte were measured in powder form and mixed in an agate mortar for 15 minutes in a dry room environment to obtain a mixture. Then, the conductive material and porous carbon additive were measured and added to the mixture, and mixed for an additional 15 minutes to obtain a mixed powder.

[0104] The mixed powder was compressed using a pressure jig to obtain a pressure of 3 mAh / cm 2 The composite positive electrode was prepared in the form of a pellet.

[0105] Example 2: Preparation of the positive electrode LiN as the positive electrode active material 0.8 Co 0.1 Mn 0.1 O2 (NCM 811), Li6PS5Cl as a sulfide-based solid electrolyte, CNF as a linear conductive material, and low-surface-area porous carbon additive 1 (Heraeus, BET 60m) as a porous carbon additive. 2 / g or less) and polytetrafluoroethylene (PTFE) as a binder to prepare a positive electrode as follows.

[0106] The positive electrode active material, sulfide-based solid electrolyte, conductive material, porous carbon additive, and binder were mixed in a weight ratio of 83:15:0.8:0.2:1 and then powder mixed. Specifically, the positive electrode active material and sulfide-based solid electrolyte were measured in powder form and mixed for 15 minutes using a blade mixer in a dry room environment to obtain a mixture. Then, the conductive material and low-porous carbon additive 1 were measured and added to the mixture and mixed. PTFE (Polytetrafluoroethylene) powder, which serves as the binder, was measured and further mixed to obtain a mixed powder.

[0107] The mixed powder was put into a mortar, and then fiberized in the mortar and calendered with a roller to prepare a positive electrode having a thickness of 150 μm.

[0108] Comparative Example 1 A composite positive electrode was prepared in the same manner as in Example 1, except that the porous carbon additive was not used.

[0109] Comparative Example 2 As a porous carbon additive, a high specific surface area porous carbon additive (Heraeus, BET 500m) was used instead of the low specific surface area porous carbon additive 1. 2 A composite positive electrode was produced in the same manner as in Example 1, except that a 0.01% Cr-based composite cathode was used.

[0110] Comparative Example 3 A positive electrode was prepared in the same manner as in Example 2, except that the porous carbon additive was not used.

[0111] Comparative Example 4 A porous carbon additive (Heraeus, BET 60m) having a smaller particle size than the porous carbon additive (low specific surface area porous additive 1) used in Example 2 was used. 2 A positive electrode was manufactured in the same manner as in Example 2, except that a porous carbon additive having a particle size smaller than that of the low specific surface area porous carbon additive 1 was used. Hereinafter, the porous carbon additive having a particle size smaller than that of the low specific surface area porous carbon additive 1 will be referred to as low specific surface area porous carbon additive 2.

[0112] Experimental example 1: Performance evaluation of all-solid-state batteries The performance of all-solid-state batteries was evaluated based on whether or not a porous carbon additive was included in the positive electrode active material layer and the specific surface area of ​​the porous carbon additive. The composite positive electrodes prepared in Example 1, Comparative Example 1, and Comparative Example 2 were evaluated.

[0113] To evaluate the performance of the all-solid-state battery, a pressure jig cell was prepared as follows.

[0114] The pellet-shaped composite cathode was transferred to a pressure jig cell, and then sulfide-based solid electrolyte powder (200 mg) was placed on the pellet and pressed at 400 MPa for 60 seconds to form a film-shaped sulfide-based solid electrolyte layer. A lithium metal anode was then placed facing one side of the sulfide-based solid electrolyte layer and pressed again at 100 MPa to increase contact between the sulfide-based solid electrolyte layer and the anode. The cells were then clamped together at an appropriate pressure to prepare a pressure jig cell.

[0115] The pressure fixture cell was activated for two cycles at 0.05 C in a charger / discharger, and then discharged up to 1 C to observe the rate characteristics (capacity capability), and the results are shown in Tables 2 and 3. Specifically, the rate characteristics were observed using a protocol of 0.05 C CC / CV (Constant Current / Constant Voltage) charge, 0.05 C CC (Constant Current) discharge for two cycles, and then CC discharge at 0.1 C / 0.2 C / 0.33 C / 0.5 C / 1 C while maintaining the 0.1 C CC / CV charge.

[0116] [Table 2]

[0117] Referring to Table 2, Example 1 and Comparative Example 1 are the cases where low specific surface area porous carbon additive 1 is included and not included, respectively, and after two cycles of formation, it was confirmed that Example 1 exhibited superior performance in terms of discharge capacity compared to Comparative Example 1. Furthermore, Example 1 and Comparative Example 2 are the cases where low specific surface area porous carbon additive 1 and high specific surface area porous carbon additive are included, respectively, and it was found that Comparative Example 2 had the same level of initial efficiency as Comparative Example 1, but slightly inferior discharge capacity.

[0118] [Table 3]

[0119] Referring to Table 3, Example 1 was found to have a superior discharge capacity retention rate compared to Comparative Examples 1 and 2. Specifically, Example 1 maintained a discharge capacity of 185 mAh / g even at 1C discharge, while Comparative Examples 1 and 2 measured discharge capacities of 170 mAh / g or less. This is due to the fact that when the specific surface area of ​​the porous carbon additive in the composite positive electrode is large (Comparative Example 2), the decomposition reaction of the sulfide-based solid electrolyte in contact with the porous carbon additive is accelerated as the C rate increases. Furthermore, when the porous carbon additive is not included in the positive electrode (Comparative Example 1), although a sufficient conductive network is formed due to the use of the linear conductive material, the porosity of the composite positive electrode in the pressure jig cell is higher than that of a positive electrode using a porous carbon additive. This is presumably responsible for the decreased lithium ion conductivity and the decreased discharge capacity retention rate.

[0120] Experimental Example 2: Confirmation of the internal structure of the positive electrode An experiment was conducted to measure the internal structure and electrical conductivity of the positive electrode depending on whether or not a porous carbon additive was included in a binder-containing positive electrode active material layer and the particle size of the porous carbon additive. Example 2, Comparative Example 3, and Comparative Example 4 were evaluated. All of these positive electrode active material layers contained a binder.

[0121] The positive electrodes prepared according to Example 2, Comparative Example 3, and Comparative Example 4 were further compressed using a warm isostatic press (WIP) to completely seal the positive electrode elements, and the sides of the positive electrodes were then observed using a scanning electron microscope (SEM). Example 2, Comparative Example 3, and Comparative Example 4 all represent cases in which a binder was used during the preparation of the positive electrodes. Example 2 contained low-specific surface area porous carbon additive 1, Comparative Example 3 did not contain a porous carbon additive, and Comparative Example 4 contained low-specific surface area porous carbon additive 2, which had a smaller particle size than Example 2.

[0122] FIG. 1 is a scanning electron microscope photograph of the side of the positive electrodes prepared using the positive electrode materials of Example 2, Comparative Example 3, and Comparative Example 4.

[0123] Referring to FIG. 1, it can be seen that Example 2 and Comparative Example 4 contain a porous carbon additive, and the dispersibility of the components contained in the positive electrode active material layer is not particularly reduced compared to Comparative Example 3, which does not contain a porous carbon additive.

[0124] In addition, the porosity was measured before and after the WIP rolling, and the electrical conductivity was measured using the prepared positive electrode, and the results are shown in Table 4. The porosity was measured using the positive electrode density calculated from 1) the thickness of the positive electrode after WIP rolling, 2) the weight of the positive electrode, 3) the area of ​​the positive electrode, and 4) the true density of the positive electrode element used, according to the following mathematical formula 1.

[0125] [Number 1] Positive electrode porosity (%) = (1 - ([positive electrode weight] / [positive electrode area × positive electrode thickness] / [positive electrode density] × 100)

[0126] In addition, the electrical conductivity (S / cm) was measured by placing an electrically conductive aluminum foil on one side of the positive electrode after manufacturing it, pressing it with a WIP to create an electrode for measuring electrical conductivity, and then measuring the resistance value (Ω·cm) obtained by placing a multi-probe of an electrode resistance measurement system (RM2610, Hioki Co.) on the electrode. The average value after three measurements was recorded.

[0127] [Table 4]

[0128] Referring to Table 4, the porosity of the positive electrode of Example 2 containing the low specific surface area porous carbon additive 1 was reduced by about 3 vol% compared to before rolling, compared to Comparative Example 3 containing no porous carbon additive. In addition, the electrical conductivity measured using the positive electrode of Example 2 was also found to be higher than those of Comparative Examples 3 and 4.

[0129] It was confirmed that the positive electrode of Comparative Example 4, which contained low specific surface area porous carbon additive 2 having a smaller particle size than low specific surface area porous carbon additive 1 of Example 2, actually increased in porosity after rolling and had the lowest electrical conductivity.

[0130] The low-specific surface area porous carbon additive 1 (D50 1.7 μm) used in Example 2 had a particle size between that of the positive electrode active material (D50 5 μm) and that of the sulfide-based solid electrolyte (D50 0.7 μm). The low-specific surface area porous carbon additive 2 used in Comparative Example 4 had a smaller particle size than the low-specific surface area porous carbon additive 1 in Example 2, and was therefore expected to more effectively fill the voids formed between the positive electrode active material and the sulfide-based solid electrolyte. However, due to its extremely small particle size and resulting fine powder, it was found to only adsorb to the surface of the positive electrode active material and not reduce the porosity of the entire positive electrode active material layer.

[0131] Therefore, it can be predicted that the low specific surface area porous carbon additive 1 used in Example 2 reduces the porosity of the positive electrode active material layer, thereby improving the performance of the positive electrode.

Claims

1. A positive electrode for an all-solid-state battery, comprising a positive electrode active material, a sulfide-based solid electrolyte, a conductive material, and a porous carbon additive, the particle size of the porous carbon additive is between the particle size of the positive electrode active material and the particle size of the sulfide-based solid electrolyte; The porous carbon additive has a BET specific surface area of ​​100 m ２ / g or less.

2. The BET specific surface area of ​​the porous carbon additive is 70 m ２ The positive electrode for an all-solid-state battery according to claim 1 , wherein the SiO 2 content is 0.15 / g or less.

3. The positive electrode for an all-solid-state battery according to claim 1, wherein the particle size (D50) of the porous carbon additive is 1.0 μm to 4.0 μm.

4. The positive electrode for an all-solid-state battery according to claim 1, wherein the porous carbon additive has a bulk density of 0.18 g / cc or more.

5. The positive electrode for an all-solid-state battery according to claim 1 , wherein the porous carbon additive has a powder resistivity of 0.05 Ω·cm or less.

6. 2. The positive electrode for an all-solid-state battery according to claim 1, wherein the particle size (D50) of the positive electrode active material is 3.0 μm to 8.0 μm.

7. 2. The positive electrode for an all-solid-state battery according to claim 1, wherein the particle size (D50) of the sulfide-based solid electrolyte is 0.1 μm to 1.5 μm.

8. 10. The positive electrode for an all-solid-state battery according to claim 1, wherein the positive electrode is in the form of a pellet containing a positive electrode active material, a sulfide-based solid electrolyte, a conductive material, and a porous carbon additive.

9. the positive electrode includes a positive electrode current collector and a positive electrode active material layer formed on one surface of the positive electrode current collector, 2. The positive electrode for an all-solid-state battery according to claim 1, wherein the positive electrode active material layer comprises a positive electrode active material, a sulfide-based solid electrolyte, a conductive material, a binder, and a porous carbon additive.

10. The binder may be polytetrafluoroethylene (PTFE), polyethylene, polypropylene, ethylene / propylene copolymer, polybutadiene, polyethylene oxide, chlorosulfonated polyethylene, polyvinylpyrrolidone, polyvinylpyridine, polyvinyl alcohol, polyvinyl acetate, polyepichlorohydrin, polyphosphazene, polyacrylonitrile, polystyrene, latex, acrylic resin, phenolic resin, epoxy resin, carboxymethyl cellulose, hydroxypropyl cellulose, cellulose 10. The positive electrode for an all-solid-state battery according to claim 9, characterized in that it contains one or more selected from the group consisting of cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate, cyanoethyl cellulose, cyanoethyl cellulose, polyester, polyamide, polyether, polyimide, polycarboxylate, polycarboxylic acid, polyacrylic acid, polyacrylate, lithium polyacrylate, polymethacrylic acid, polymethacrylate, polyacrylamide, polyurethane, polyvinylidene fluoride, and poly(vinylidene fluoride)-hexafluoroprofen.

11. 2. The positive electrode for an all-solid-state battery according to claim 1, wherein the conductive material is at least one linear conductive material selected from the group consisting of carbon nanotubes (CNTs) and carbon nanofibers (CNFs).

12. 2. The positive electrode for an all-solid-state battery according to claim 1, wherein the porous carbon additive is at least one selected from the group consisting of soft carbon and hard carbon.

13. The positive electrode for an all-solid-state battery according to claim 1, wherein the porous carbon additive is at least one selected from the group consisting of activated carbon and carbon black.

14. The positive electrode for an all-solid-state battery according to claim 1, wherein the positive electrode has a porosity of 5 vol% to 19 vol%.

15. The positive electrode active material is included in an amount of 55 to 90 wt % based on the total weight of the positive electrode, The sulfide-based solid electrolyte is included in an amount of 10 to 50 wt % based on the total weight of the positive electrode, The conductive material is contained in an amount of 0.05 to 10 wt % based on the total weight of the positive electrode, 10. The positive electrode for an all-solid-state battery according to claim 1, wherein the porous carbon additive is included in an amount of 0.1 to 3 wt % based on the total weight of the positive electrode.

16. An all-solid-state battery comprising the positive electrode according to claim 1, a negative electrode, and a sulfide-based solid electrolyte layer interposed therebetween.

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