Positive electrode for all-solid-state batteries and all-solid-state batteries containing 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] This invention claims priority under Korean Patent Application No. 10-2023-0094993 dated July 21, 2023, and all content disclosed in the said Korean Patent Application is incorporated herein by reference.

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

[0003] From the perspectives of battery capacity, safety, output, scaling up, and miniaturization, various types of batteries are currently being researched that can overcome the limitations of lithium-ion secondary batteries.

[0004] Typically, metal-air batteries, which have a much larger theoretical capacity than lithium-ion batteries; all-solid-state batteries, which are safe and do not pose an explosion risk; supercapacitors, which offer greater power output; NaS batteries or RFBs (redox flow batteries), which are designed for larger sizes; and thin-film batteries, which are designed for ultra-miniaturization, are all being continuously researched in academia and industry.

[0005] Among various next-generation batteries, all-solid-state batteries refer to batteries that replace the liquid electrolyte used in conventional lithium-ion secondary batteries with a solid electrolyte. Because they do not use flammable solvents in the battery, they completely eliminate the risk of ignition or explosion due to the decomposition reaction of conventional electrolytes, thus 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 in the solid electrolyte and can theoretically achieve high energy densities of 900 Wh / L or more. 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 does not occur through the liquid electrolyte found in conventional lithium-ion batteries (LIBs). Therefore, when manufacturing positive electrodes for sulfide-based all-solid-state batteries, it is necessary to add small-particle sulfide-based solid electrolyte particles to the inside of the positive electrode to increase the contact interface between the positive electrode active material and the sulfide-based solid electrolyte particles, thereby increasing lithium ion conduction. Furthermore, to improve energy density, it is necessary to promote physical contact between the positive electrode active material, sulfide-based solid electrolyte particles, and other battery elements within the positive electrode, and to reduce the porosity of the positive electrode after rolling, which must be maintained during charging and discharging.

[0007] Therefore, there is a constant need to develop technologies that can further reduce the porosity of the positive electrode in sulfide-based all-solid-state batteries and improve the performance of all-solid-state batteries. [Prior art documents] [Patent Documents]

[0008] [Patent Document 1] Korean Published Patent Publication No. 2016-0118597 [Overview of the Initiative] [Problems that the invention aims to solve]

[0009] The inventors conducted multifaceted research to solve the aforementioned problems and found that when manufacturing the positive electrode active material layer of a positive electrode for an all-solid-state battery, a positive electrode active material, a sulfide-based solid electrolyte, a conductive material, and a porous carbon additive are used. They also found that when the particle size of the porous carbon additive is used to be between the particle size of the positive electrode active material and the particle size of the sulfide-based solid electrolyte so as to fill the gaps between the particles of the positive electrode active material and the sulfide-based solid electrolyte, and at the same time, when the specific surface area of ​​the porous carbon additive is limited to below a certain level, the porosity of the positive electrode active material layer is reduced, and the energy density of the all-solid-state battery is improved.

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

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

Means for Solving the Problems

[0012] To achieve the above object, the present invention provides a positive electrode for an all-solid-state battery including a positive electrode active material, a sulfide-based solid electrolyte, a conductive material, and a porous carbon additive, wherein 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 is a low specific surface area porous carbon additive with a BET specific surface area of 100 m 2 / g or less.

[0013] The present invention also provides a positive electrode for an all-solid-state battery, wherein the BET specific surface area of the porous carbon additive is 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 bulk density of the porous carbon additive is 0.18 g / cc or more.

[0016] The present invention also provides a positive electrode for an all-solid-state battery, wherein the powder resistance of the porous carbon additive is 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, characterized in that 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, characterized in that 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 includes 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 for an all-solid-state battery is provided, characterized in that 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.

[0021] The present invention also provides a positive electrode for an all-solid-state battery, characterized in that the binder comprises 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, carboxymethylcellulose, hydroxypropylcellulose, cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate, cyanoethylcellulose, cyanoethyl scrophulari, 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, characterized in that 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, characterized in that the porous carbon additive is one or more 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, characterized in that the porous carbon additive is one or more 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, characterized in that the porosity of the positive electrode is 5 vol% to 19 vol%.

[0026] The present invention also states that the positive electrode active material is present in an amount of 55 to 90% by weight based on the total weight of the positive electrode. The aforementioned sulfide-based solid electrolyte is present in an amount of 10 to 50% by weight, based on the total weight of the positive electrode. The conductive material is included in an amount of 0.05 to 10% by weight based on the total weight of the positive electrode. The present invention provides a positive electrode for an all-solid-state battery, characterized in that the porous carbon additive is present in an amount of 0.1 to 3% by weight based on the total weight of the positive electrode.

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

[0028] According to the positive electrode for all-solid-state batteries of the present invention, the porous carbon additive fills the voids between the particles of the positive electrode active material and the sulfide-based solid electrolyte, thereby reducing the porosity of the positive electrode and 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 of the all-solid-state battery, the conductivity of the positive electrode is maintained, thus improving the energy density without degrading the performance of the all-solid-state battery. [Brief explanation of the drawing]

[0029] [Figure 1] These are scanning electron microscope images of the positive electrode side surface produced in Example 2, Comparative Example 3, and Comparative Example 4. [Modes for carrying out the invention]

[0030] The present invention will be described in more detail below to aid in understanding the present invention.

[0031] The terms and words used in this specification and in the claims shall not be interpreted in a manner limited to their ordinary or lexicographical meanings, but rather in a manner consistent with the technical idea of ​​the present invention, based on the principle that inventors may appropriately define the concepts of terms in order to best describe their invention.

[0032] In this specification, in order to distinguish between positive electrodes manufactured based on whether or not the positive electrode active material layer contains a binder, a positive electrode without a binder may be referred to as a "composite positive electrode," and a positive electrode with a binder may be referred to as a "positive electrode."

[0033] Positive electrode for all-solid-state batteries This invention relates to a positive electrode for all-solid-state batteries.

[0034] The positive electrode for an all-solid-state battery according to the present invention comprises 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 pelletized positive electrode may be used free from the current collector, or the pellet may be placed on the current collector to form the positive electrode. The pellet may be formed by pressurizing 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 the 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 m². 2 The amount may be less than or equal to / g. The conductive material may be a linear conductive material, taking into consideration its specific surface area. In this specification, a positive electrode without 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 particle size difference between the positive electrode active material and the sulfide-based solid electrolyte particles, and these 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 is 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, so the voids may be filled 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 m². 2 It may be less than / g. Specifically, the specific surface area of ​​the porous carbon additive is 100m². 2 / g or less, 90m 2 / g or less, 80m 270 m or less, / g 2 60 m or less, / g 2 50 m or less, / g 2 40 m or less, / g 2 30 m or less, / g 2 It may be / g or less. If the BET specific surface area exceeds 100 m 2 / g, the contact interface between the high specific surface area porous carbon additive and the sulfide-based all-solid electrolyte for the positive electrode increases, the electrolyte decomposition reaction increases, and the ionic conductivity of the positive electrode itself may decrease. Further, the lower limit value of the BET specific surface area is not particularly limited, but it may be 5 m 2 / g or more.

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

[0041] Also, 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, and may be 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 are too small, and rather than filling the voids formed by the particle size difference between the positive electrode active material and the sulfide-based solid electrolyte particles, the porous carbon additive may be adsorbed only on the surface of the positive electrode active material. If it exceeds 4.0 μm, it is difficult to fill the voids formed by the particle size difference 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 introducing the porous carbon additive into a particle size analyzer (Particle size analyzer, Mastersizer 3000, Malvern).

[0043] Also, the bulk density of the porous carbon additive may be 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 is low, which may reduce the overall density of the positive electrode. The upper limit of the bulk density is not particularly limited, but it may be 0.5 g / cc or less.

[0045] The aforementioned bulk density can be measured using a densimeter conforming to the ASTM D 1895 method.

[0046] Furthermore, the powder resistivity of the porous carbon additive may be 0.05 Ω·cm or less.

[0047] Specifically, the powder resistance may be 0.05 Ω·cm or less, 0.04 Ω·cm or less, or 0.03 Ω·cm or less. If the powder resistance exceeds 0.05 Ω·cm, the overall resistance of the positive electrode may increase if the porous carbon additive is present in the positive electrode at a certain fraction or higher. The lower limit of the powder resistance is not particularly limited, but may be 0.005 Ω·cm or higher. If the powder resistance becomes excessively low, electron transfer between the porous carbon additive and the sulfide-based all-solid electrolyte in contact becomes active, and the sulfide-based all-solid electrolyte may undergo a decomposition reaction.

[0048] The aforementioned powder resistance can be measured using a powder resistance meter (HPRM-FA2, Hantech). After attaching the lower punch to the body of the powder resistance mold, the conductive material sample with a known weight is quantified, the upper punch is attached, and the sample is placed inside the powder resistance meter. Then, the powder resistance meter is operated to pressurize from 0 to 2000 kgf in 400 kgf increments, and the final powder resistance can be observed at 2000 kgf (196 MPa).

[0049] Furthermore, the porous carbon additive may include one or more selected from the group consisting of soft carbon and hard carbon, and is not limited to any particulate carbon material. For example, the porous carbon additive may be one or more selected from activated carbon and carbon black.

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

[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, and may be 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 electrolyte are dispersed in the same weight ratio, the particle size of the positive electrode active material may be small and the dispersibility may decrease. If it exceeds 7.0 μm, excessively large voids may be formed within the positive electrode active material layer, which may degrade the performance of the all-solid-state battery.

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

[0054] Furthermore, the positive electrode active material is not particularly limited as long as it is a material capable of reversibly intercalating and releasing lithium ions, for example, lithium cobalt oxide (LiCoO2), lithium nickel oxide (LiNiO2), Li[Ni x Co y Mn z M v ]O2(In the above formula, 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, x+y+z+v=1), Li(Li a M b-a-b’ M' b’ )O 2-c A c (In the above formula, 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; A is one or more elements selected from the group consisting of P, F, S, and N.) Layered compounds such as or compounds substituted with one or more transition metals; chemical formula Li 1+y Mn 2-y Lithium manganese oxides such as O4 (where y is 0 to 0.33), LiMnO3, LiMn2O3, LiMnO2; lithium copper oxide (Li2CuO2); vanadium oxides such as LiV3O8, LiFe3O4, V2O5, Cu2V2O7; chemical formula LiNi 1-y Ni-site type lithium nickel oxide represented as 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 include, but are not limited to, lithium manganese composite oxides represented as O2 (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 alkaline earth metal ions; disulfide compounds; Fe2(MoO4)3, etc.

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

[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, and may be 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 it is greater than 1.5 μm, dispersion is somewhat easier, but the contact surface with the positive electrode active material particles decreases, and the positive electrode porosity may increase.

[0058] Furthermore, the sulfide-based solid electrolyte 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 to these, and a wide range of sulfide-based solid electrolytes commonly used in the industry may be used.

[0059] Furthermore, the sulfide-based solid electrolyte may be included in an amount of 10 to 50% by weight based on the total weight of the positive electrode active material layer. Specifically, the content of the sulfide-based solid electrolyte may be 10% by weight or more, 20% by weight or more, or 30% by weight or more, or 40% by weight or less, 45% by weight or less, or 50% by weight or less. If the content of the positive electrode active material is less than 10% by weight, it may not be sufficient to fill the voids formed in the positive electrode active material layer, making it difficult to reduce the porosity of the positive electrode active material. If it exceeds 50% by weight, the relative content of the positive electrode active material and conductive material may decrease, potentially degrading 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 (CNTs) and carbon nanofibers (CNFs). The linear conductive material can improve electrical conductivity due to its shape characteristics.

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

[0062] In one embodiment of the present invention, the positive electrode active material layer may further contain a binder. The binder may be included to assist in the bonding between substances contained in the positive electrode active material layer and the bonding between the positive electrode active material layer and the positive electrode current collector. The binder may promote bonding between substances contained in the positive electrode active material layer, potentially further reducing the positive electrode porosity.

[0063] The binder may be a fibrous binder. During the manufacturing of the positive electrode, the binder may undergo fibrous formation during the mixing process and be included 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] Furthermore, the binder may contain 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, carboxymethylcellulose, hydroxypropylcellulose, cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate, cyanoethylcellulose, cyanoethyl scrophulari, 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 contain polytetrafluoroethylene (PTFE).

[0065] Furthermore, the binder may be included in an amount of 0.1 to 3% by weight based on the total weight of the positive electrode active material layer. Specifically, the binder content may be 0.1% or more by weight, 0.5% or more by weight, or 0.8% or more by weight, and may be 1.5% or less by weight, 2% or less by weight, or 3% or less by weight. If the binder content is less than 0.1% by weight, the effect of improving the bonding strength between substances contained in the positive electrode active material layer will be negligible, which may result in the electrode sheet not being properly formed. If it exceeds 3% by weight, the ionic conductivity or electrical conductivity may decrease.

[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 also be 17 vol%, 18 vol% or less, or 19 vol% or less. The porosity is within an optimized range considering the performance of the battery, such as its energy density, 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, and may be 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 appropriate positive electrode loading in accordance with improvements in the performance of the 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 plays a role in transferring electrons between the 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 chemical changes 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, calcined carbon, stainless steel surface-treated with carbon, nickel, silver, etc., or aluminum-cadmium alloy.

[0071] The positive electrode current collector may have a fine uneven surface or a three-dimensional porous structure to enhance the bonding force with the positive electrode active material layer. As a result, the positive electrode current collector may include various forms such as film, sheet, foil, mesh, net, porous material, foam, and nonwoven fabric.

[0072] Manufacturing method for positive electrodes for all-solid-state batteries The present invention also relates to a method for manufacturing a positive electrode for an all-solid-state battery. The specific substances, properties, and content 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 as a "composite positive electrode" if it does not contain a binder, and as a "positive electrode" if it does contain a binder, depending on whether or not it contains a binder.

[0074] In one embodiment of the present invention, a method for manufacturing a binder-free composite cathode may include the steps of (A1) mixing a cathode active material, a sulfide-based solid electrolyte, a conductive material, and a porous carbon additive; and (A2) manufacturing the mixed powder obtained in step (A1) into pellets. In this case, the pellets in step (A2) may be formed by pressurizing with a jig.

[0075] The composite positive electrode manufactured as described above may be applied to a pressure jig cell. Since the composite positive electrode does not contain a binder, the factor of the binder acting as resistance can be eliminated. Therefore, performance evaluation can be performed using the composite positive electrode with a pressure jig cell from which resistance factors have been eliminated.

[0076] Furthermore, in one embodiment of the present invention, a method for producing a positive electrode including a binder includes: (B1) mixing a positive electrode active material, a sulfide-based solid electrolyte, a conductive material, and a porous carbon additive binder; (B2) applying the mixed powder obtained in step (B1) to a calendering process to form 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 a physical mixing, and the binder can be fibrousized by such physical mixing. During the physical mixing, the binder is rubbed against the particles in the mixed powder by shear force, causing physical deformation and fibrousization. For example, PTFE, which has physical properties that allow physical deformation to occur well, may be used as the binder. Alternatively, a mortar and pestle, ball mill, or roll press may be introduced during mixing to ensure that physical deformation occurs well.

[0078] In addition, in step (B2), the mixed powder obtained in step (B1) may be applied to a calendering process to form a film.

[0079] The conditions for the calendering process may be appropriately controlled and applied to process conditions that allow for film formation. For example, the calendering process may be carried out at a temperature of 50°C to 200°C for 5 to 50 loops. However, the calendering process 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 step (B3), the film-like positive electrode active material layer obtained in step (B2) may be attached to a positive electrode current collector to manufacture 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 comprising a sulfide-based solid electrolyte layer.

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

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

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

[0085] In the negative electrode active material layer, the negative electrode active material is lithium (Li + The material may include a substance that can be reversibly intercalated or deintercalated, a substance that can react with lithium ions to reversibly form a lithium-containing compound, or a lithium metal or lithium alloy.

[0086] The aforementioned lithium ion (Li + The material that can reversibly insert or remove the lithium ion (Li) may be, for example, crystalline carbon, amorphous carbon, or a mixture thereof. +A substance that can reversibly form a lithium-containing compound by reacting with ) 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 lithium-indium alloy (Li-In), and more specifically, it may be lithium metal or lithium in thin film, lithium-indium alloy thin film, or powder.

[0088] The negative electrode active material may be present in an amount of 40 to 80% by weight based on the total weight of the negative electrode active material layer. Specifically, the content of the negative electrode active material may be 40% by weight or more, or 50% by weight or more, or 70% by weight or less, or 80% by weight or less. If the content of the negative electrode active material is less than 40% by weight, 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% by weight, the mass transfer resistance may increase.

[0089] Furthermore, the binder contains components that assist in the bonding of the negative electrode active material to conductive materials and to the negative electrode current collector, such as styrene-butadiene rubber, acrylic 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, and polyacrylic. The binder may contain one or more selected from the group consisting of lilonitrile, polystyrene, latex, acrylic resin, phenolic resin, epoxy resin, carboxymethylcellulose, hydroxypropylcellulose, cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate, cyanoethylcellulose, cyanoethyl scrophulari, 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 contain polytetrafluoroethylene (PTFE).

[0090] Furthermore, the binder may be included in an amount of 0.5% to 4% by weight based on the total weight of the negative electrode active material layer. Specifically, the binder content may be 0.5% or more by weight, 1% or more by weight, or 1.5% or more by weight, or 3% or less by weight, 3.5% or less by weight, or 4% or less by weight. If the binder content is less than 0.5% by weight, the adhesive strength between the positive electrode active material and the negative electrode current collector may decrease. If it exceeds 4% by weight, the adhesive strength will improve, but the content of the negative electrode active material will decrease accordingly, potentially reducing the battery capacity.

[0091] Furthermore, 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. Typically, graphite or conductive carbon may be used, for example, graphite such as natural graphite or artificial graphite; carbon black such as carbon black, acetylene black, Ketjen black, Denka black, thermal black, channel black, furnace black, lamp black, and summer black; carbon-based materials whose crystalline structure is graphene or graphite; conductive fibers such as carbon fibers and metal fibers; carbon fluoride; metal powders such as aluminum powder and nickel powder; conductive whiskers such as zinc oxide and potassium titanate; conductive oxides such as titanium oxide; and conductive polymers such as polyphenylene derivatives; which may be used alone or in mixtures of two or more, but are not necessarily limited to these. Preferably, the conductive material may also contain vapor-grown carbon fiber (VGCF).

[0092] The conductive material may typically be present in an amount of 1% to 5% by weight based on the total weight of the negative electrode active material layer. Specifically, the content of the conductive material may be 1% or more by weight, 1.5% or more by weight, or 2% or more by weight, or 4% or less by weight, 4.5% or less by weight, or 5% or less by weight. If the content of the conductive material is too low (less than 1% by weight), the effect of improving electrical conductivity may not be expected, or the electrochemical properties of the battery may deteriorate. If it is too high (more than 5% by weight), the amount of negative electrode active material will be relatively small, and the capacity and energy density may decrease. The method of incorporating the conductive material into the negative electrode is not broadly limited, and conventional methods known in the art, such as mixing with the negative electrode active material or coating, may be used.

[0093] Furthermore, 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. For example, the negative electrode current collector may be made of copper, stainless steel, aluminum, nickel, titanium, calcined carbon, copper or stainless steel surface-treated with carbon, nickel, titanium, silver, etc., or aluminum-cadmium alloy. Also, similar to the positive electrode current collector, the negative electrode current collector may be made of various forms such as films, sheets, foils, nets, porous materials, foams, or nonwoven fabrics with fine irregularities formed on their surface.

[0094] The method for manufacturing the negative electrode is not particularly limited, and it can 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 industry. For example, methods such as crimping, coating, and vapor deposition may be used. Furthermore, the negative electrode of the present invention is also included in the case where a metallic lithium thin film is formed on a metal plate by initial charging after the battery has been assembled without a lithium thin film on the negative electrode current collector.

[0095] Furthermore, the term "negative electrode layer" refers to a negative electrode layer in which, during the initial assembly of the battery, lithium metal or lithium alloy, which serves as a lithium supply source among the negative electrode active materials, is not present in the negative electrode, but lithium is deposited in the negative electrode during charging. A battery containing this negative electrode layer can also be called a negative electrode-free battery.

[0096] In the aforementioned negative electrode-free battery, as the battery charges and discharges, lithium ions released from the positive electrode move to the negative electrode to form a negative electrode active material layer. For example, during charging of the battery, lithium ions are detached from the positive electrode active material and then move to the negative electrode side, becoming lithium metal composed purely of lithium. This can form a layered lithium metal layer on the negative electrode current collector, or a lithium metal structure of any shape rather than a layered one. Any shape could be, for example, a structure in which lithium metal is aggregated into particulate matter.

[0097] In one embodiment of the present invention, the sulfide-based solid electrolyte contained 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 to these, and a wide range of sulfide-based solid electrolytes commonly used in the industry may be used.

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

[0099] Specific examples of the devices mentioned above include, but are not limited to, power tools powered by battery-powered motors; 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 are shown below to aid in understanding the present invention, but these embodiments are illustrative of the present invention, and it will be obvious to those skilled in the art that various changes and modifications are possible within the scope of the present invention and the technical concept, and that such variations and modifications will naturally fall within the scope of the appended claims.

[0100] In the following examples and comparative examples, a positive electrode and an all-solid-state battery containing it were manufactured according to the composition 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: Manufacturing of a composite cathode 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, and carbon nanofiber (CNF) and porous carbon additive (Heraeus, BET 60m) as conductive materials. 2 A positive electrode was manufactured using (less than / g) as described below. Hereinafter, the porous carbon additive will be 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 powder mixing was performed. Specifically, the positive electrode active material and sulfide-based solid electrolyte were quantified in powder form and then mixed in a dry room environment using an agate mortar for 15 minutes to obtain a mixture. Subsequently, the conductive material and porous carbon additive were quantified and added to the mixture, and then mixed for another 15 minutes to obtain a mixed powder.

[0104] The mixed powder is pressurized using a pressurizing jig to a pressure of 3 mAh / cm². 2 The composite cathode was manufactured in the form of a pellet for loading.

[0105] Example 2: Manufacturing of a 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 specific surface area porous carbon additive 1 (Heraeus, BET 60m) as a porous carbon additive. 2 The positive electrode was manufactured as follows using a phosphate group (less than / g) and polytetrafluoroethylene (PTFE) as a binder.

[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 powder mixing was performed. Specifically, the positive electrode active material and sulfide-based solid electrolyte were quantified in powder form, and then mixed in a dry room environment using a blade mixer for 15 minutes to obtain a mixture. Subsequently, the conductive material and low-porous carbon additive 1 were quantified and added to the mixture, then mixed, and the binder, PTFE (Polytetrafluoroethylene) powder, was quantified and further mixed to obtain a mixed powder.

[0107] After placing the aforementioned mixed powder into a mortar, the fibrous material was processed in the mortar, followed by calendering with a roller to produce a cathode with a thickness of approximately 150 μm.

[0108] Comparative Example 1 A composite cathode was manufactured in the same manner as in Example 1, except that a porous carbon additive was not used.

[0109] Comparative Example 2 As a porous carbon additive, instead of low specific surface area porous carbon additive 1, a high specific surface area porous carbon additive (Heraeus, BET 500m) is used. 2 A composite cathode was manufactured in the same manner as in Example 1, except that a sample of 1 (1 / g or more) was used.

[0110] Comparative Example 3 The cathode was manufactured in the same manner as in Example 2, except that a porous carbon additive was not used.

[0111] Comparative Example 4 Compared to the porous carbon additive used in Example 2 (low specific surface area porous additive 1), this porous carbon additive has a smaller particle size (Heraeus, BET 60m 2 The positive electrode was manufactured in the same manner as in Example 2, except that a low specific surface area porous carbon additive (less than / g) was used. Hereinafter, a porous carbon additive with a smaller particle size than 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 manufactured in Example 1, Comparative Example 1, and Comparative Example 2 were evaluated.

[0113] To evaluate the performance of the aforementioned all-solid-state battery, a pressure jig cell was manufactured using the following method.

[0114] After transferring the pelletized composite positive electrode to a pressure jig cell, 200 mg of sulfide-based solid electrolyte powder was placed on top of the pellet, and pressure was applied at 400 MPa for 60 seconds to form a film-like sulfide-based solid electrolyte layer. Subsequently, the lithium metal negative electrode was placed facing one surface of the sulfide-based solid electrolyte layer, and pressure was applied again at 100 MPa to increase the contact between the sulfide-based solid electrolyte layer and the negative electrode. Finally, the cells were fastened at an appropriate pressure to manufacture the pressure jig cell.

[0115] The capacity capability of the aforementioned pressure jig cell was observed through a protocol in which it was activated at 0.05C for two cycles using a charger / discharger, and then discharged up to a maximum of 1C. The results are shown in Tables 2 and 3 below. Specifically, the capacity capability was observed through a protocol in which the charger / discharger was charged at 0.05C CC / CV (Constant Current / Constant Voltage), discharged at 0.05C CC (Constant Current) for two cycles, and then discharged at 0.1C / 0.2C / 0.33C / 0.5C / 1C while maintaining the 0.1C CC / CV charging process.

[0116] [Table 2]

[0117] Referring to Table 2 above, Example 1 and Comparative Example 1 were the cases with and without the low specific surface area porous carbon additive 1, respectively. After performing a two-cycle formation, it was confirmed that Example 1 showed superior performance in terms of discharge capacity compared to Comparative Example 1. Furthermore, Example 1 and Comparative Example 2 were the cases with and without the low specific surface area porous carbon additive 1 and high specific surface area porous carbon additive, respectively. In the case of Comparative Example 2, the initial efficiency was at the same level as Comparative Example 1, but the discharge capacity was slightly inferior.

[0118] [Table 3]

[0119] Referring to Table 3 above, it was confirmed that Example 1 had superior discharge capacity retention 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 were measured to have a discharge capacity of 170 mAh / g or less. This is due to the phenomenon 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, in the case where the porous carbon additive is not included in the positive electrode (Comparative Example 1), although a conductive network is sufficiently formed by the use of linear conductive material, it can be inferred that the porosity of the composite positive electrode in the pressure jig cell is higher than that of the positive electrode using a porous carbon additive, which reduces lithium ion conductivity and thus reduces the discharge capacity retention rate.

[0120] Experimental Example 2: Confirmation of the internal structure of the positive electrode Experiments were conducted to determine whether or not porous carbon additives were included in the positive electrode active material layer containing the binder, and to measure the internal structure and electrical conductivity of the positive electrode based on the particle size of the porous carbon additives. Examples 2, Comparative Example 3, and Comparative Example 4 were evaluated. All of these included a binder in the positive electrode active material layer.

[0121] The positive electrodes prepared according to Example 2, Comparative Example 3, and Comparative Example 4 were further pressurized using a WIP (Warm Isostatic Press) to ensure complete contact between the positive electrode elements, after which the sides of the positive electrodes were observed with a scanning electron microscope (SEM). In all cases, a binder was used during the manufacturing of the positive electrodes. Example 2 contained a low specific surface area porous carbon additive 1, Comparative Example 3 did not contain a porous carbon additive, and Comparative Example 4 contained a low specific surface area porous carbon additive 2 with a smaller particle size compared to Example 2.

[0122] Figure 1 shows scanning electron microscope images of the side surface of the positive electrode manufactured using the positive electrode materials of Example 2, Comparative Example 3, and Comparative Example 4.

[0123] Referring to Figure 1, it can be seen that Example 2 and Comparative Example 4 contain porous carbon additives, and compared to Comparative Example 3, which does not contain porous carbon additives, the dispersibility of the constituent materials in the positive electrode active material layer is not reduced.

[0124] Furthermore, the porosity was measured before and after the WIP rolling process, and the electrical conductivity was measured using the manufactured positive electrode. The results are shown in Table 4 below. At this time, 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 elements used, according to the following mathematical formula 1.

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

[0126] Furthermore, the electrical conductivity (S / cm) was measured by first creating an electrode for electrical conductivity measurement after the positive electrode was manufactured, by placing an electrically conductive Al foil on one side, and then pressurizing it with WIP (Wipe-In Press). The resistance value (Ω·cm) obtained by facing the electrode with a multi-probe of an electrode resistance measurement system (RM2610, Hioki Corporation) was then calculated by taking the reciprocal of the value, and the average value was recorded after three measurements.

[0127] [Table 4]

[0128] Referring to Table 4 above, the positive electrode porosity of Example 2, which contains low specific surface area porous carbon additive 1, decreased by approximately 3 vol% compared to Comparative Example 3, which does not contain porous carbon additive, compared to before rolling. Furthermore, it was confirmed that the electrical conductivity measured using the positive electrode of Example 2 was also greater than that of Comparative Examples 3 and 4.

[0129] Compared to the low specific surface area porous carbon additive 1 of Example 2, the cathode of Comparative Example 4, which contained the low specific surface area porous carbon additive 2 having a smaller particle size, was found to have increased porosity and the lowest electrical conductivity after rolling.

[0130] The low specific surface area porous carbon additive 1 (D50 1.7 μm) used in Example 2 has a particle size between that of the positive electrode active material (D50 5 μm) and the sulfide-based solid electrolyte (D50 0.7 μm). The low specific surface area porous carbon additive 2 used in Comparative Example 4 has a smaller particle size than the low specific surface area porous carbon additive 1 in Example 2, and was expected to more effectively fill the voids formed by the positive electrode active material and the sulfide-based solid electrolyte. However, it was confirmed that, rather, due to its extremely low particle size and the resulting fine powder, it adsorbed only on the surface of the positive electrode active material and was unable to 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 will reduce 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 m². ２ A positive electrode for all-solid-state batteries, characterized by being a low specific surface area porous carbon additive of less than / g.

2. The BET specific surface area of ​​the porous carbon additive is 70 m². ２ A positive electrode for an all-solid-state battery according to claim 1, characterized in that it is less than or equal to / g.

3. The positive electrode for an all-solid-state battery according to claim 1, characterized in that 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, characterized in that the bulk density of the porous carbon additive is 0.18 g / cc or more.

5. The positive electrode for an all-solid-state battery according to claim 1, characterized in that the powder resistance of the porous carbon additive is 0.05 Ω·cm or less.

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

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

8. The positive electrode for an all-solid-state battery according to claim 1, characterized in that 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. The positive electrode for an all-solid-state battery according to claim 1, characterized in that 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 binders include 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, carboxymethylcellulose, hydroxypropylcellulose, and cellulose. A positive electrode for an all-solid-state battery according to claim 9, characterized by comprising one or more selected from the group consisting of cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate, cyanoethylcellulose, 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.

11. The positive electrode for an all-solid-state battery according to claim 1, characterized in that the conductive material is one or more linear conductive materials selected from the group consisting of carbon nanotubes (CNT) and carbon nanofibers (CNF).

12. The positive electrode for an all-solid-state battery according to claim 1, characterized in that the porous carbon additive is one or more 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, characterized in that the porous carbon additive is one or more 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, characterized in that the porosity of the positive electrode is 5 vol% to 19 vol%.

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

16. An all-solid-state battery comprising a positive electrode, a negative electrode, and a sulfide-based solid electrolyte layer interposed between them, as described in claim 1.

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