Cathode for all-solid-state battery and all-solid-state battery comprising same

Abstract

The present invention relates to a cathode for an all-solid-state battery and an all-solid-state battery comprising same. More specifically, when a cathode for an all-solid-state battery is manufactured by a dry process, the content of a conductive material included in a cathode active material layer is controlled to enhance electronic conductivity and improve the performance of an all-solid-state battery.

Description

Anode for all-solid-state batteries and all-solid-state batteries including the same

[0001] Cross-citation with related applications

[0002] This application claims the benefit of priority based on Korean Patent Application No. 10-2024-0129553 filed September 25, 2024, and all contents disclosed in the document of said Korean patent application are incorporated into this specification.

[0003] Technology field

[0004] The present invention relates to a positive electrode for an all-solid-state battery and an all-solid-state battery including the same.

[0005] Various batteries capable of overcoming the current limitations of lithium-ion batteries are being researched in terms of capacity, safety, output, scaling up, and miniaturization.

[0006] Continuous research is being conducted in academia and industry on representative technologies, including metal-air batteries, which have a much larger theoretical capacity compared to lithium-ion batteries; all-solid-state batteries, which pose no risk of explosion in terms of safety; supercapacitors in terms of output; NaS batteries or RFBs (redox flow batteries) in terms of scale; and thin-film batteries in terms of miniaturization.

[0007] Among various next-generation batteries, all-solid-state batteries refer to batteries in which the liquid electrolyte used in conventional lithium-ion batteries is replaced with a solid electrolyte. Since flammable solvents are not used within the battery, there is absolutely no ignition or explosion caused by decomposition reactions of conventional electrolytes, thereby significantly improving safety. Furthermore, among all-solid-state batteries, technological development is continuing for sulfide-based all-solid-state batteries, which can achieve a high energy density of theoretically over 900 Wh / L while having high ionic conductivity of the solid electrolyte. In this context, a sulfide-based all-solid-state battery refers to an all-solid-state battery containing a sulfide-based solid electrolyte.

[0008] In all-solid-state battery systems, lithium ion conduction does not occur through the liquid electrolyte contained in conventional lithium-ion batteries (LIBs). Therefore, when manufacturing cathodes for sulfide-based all-solid-state batteries, small-diameter 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, physical contact between the cathode active material, sulfide-based solid electrolyte particles, and other components within the cathode must be enhanced, and the porosity after rolling the cathode must be reduced and maintained throughout the charging and discharging cycles.

[0009] Accordingly, a technology has been developed to increase and maintain the contact interface between the cathode active material and sulfide-based solid electrolyte particles by introducing a fibrous binder into the cathode. Fibrous binders can be formed as the binder fiberizes when the cathode is manufactured using a solvent-free dry process. Therefore, to obtain a fibrous binder, a binder that fiberizes easily can be introduced into the dry process; for example, poly(tetrafluoroethylene) (PTFE) is a binder that fiberizes easily.

[0010] However, simply introducing a fibrous binder into the cathode of an all-solid-state battery has limitations in reducing the porosity of the cathode. Therefore, there is a need for the development of technology capable of further reducing the porosity of the all-solid-state battery cathode into which the fibrous binder has been introduced.

[0011]

[0012] Meanwhile, for all-solid-state batteries, the cathode requires not only ionic conductivity but also electronic conductivity as a key physical property. To improve the electronic conductivity of the cathode, it is necessary to facilitate electron movement between the cathode active material, sulfide-based solid electrolyte particles, and other components within the cathode. Accordingly, the development of technology capable of enhancing electronic conductivity by facilitating electron movement within the cathode is also required.

[0013] [Prior Art Literature]

[0014] (Patent Document 1) U.S. Published Patent No. 2024-0079574

[0015] As a result of conducting multifaceted research to solve the above problem, the inventors confirmed that by controlling the content of a conductive material in a cathode for an all-solid-state battery containing a fibrous binder, both ionic conductivity and electronic conductivity can be improved.

[0016] Accordingly, the objective of the present invention is to provide a positive electrode for an all-solid-state battery in which the content of the conductive material is controlled.

[0017] In addition, another objective of the present invention is to provide a method for manufacturing a positive electrode for an all-solid-state battery in which the content of the conductive material is controlled.

[0018] In addition, another objective of the present invention is to provide an all-solid-state battery comprising a positive electrode for an all-solid-state battery in which the content of the conductive material is controlled.

[0019] To achieve the above objective, the present invention provides a positive electrode for an all-solid-state battery comprising a positive electrode active material layer including a positive electrode active material, a sulfide-based solid electrolyte, a conductive material, and a fibrous binder, wherein

[0020] The present invention provides a positive electrode for an all-solid-state battery, wherein the conductive material is included in an amount of 0.1 weight% or more based on the total weight of the positive electrode active material layer.

[0021] In one embodiment of the present invention, a positive electrode for an all-solid-state battery is provided, wherein the conductive material comprises one or more selected from the group consisting of graphite, carbon black, carbon nanotube, carbon fiber, and graphene.

[0022] In one embodiment of the present invention, the fibrous binder is a fluorine-containing fibrous binder, and the fluorine-containing fibrous binder comprises one or more selected from the group consisting of polytetrafluoroethylene (PTFE) and copolymers containing the same, thereby providing a positive electrode for an all-solid-state battery.

[0023] In one embodiment of the present invention, a positive electrode for an all-solid-state battery is provided, wherein the relative fiberization degree (A) of the positive electrode is calculated by the following formula 1 and is 4 to 6:

[0024] <Equation 1>

[0025] A = Fluorine element content on the surface of the positive active material layer (F1, wt%) / Fluorine element content inside the positive active material layer (F2, wt%).

[0026] In one embodiment of the present invention, a positive electrode for an all-solid-state battery is provided, wherein the positive electrode active material comprises a surface coating layer.

[0027] In one embodiment of the present invention, a positive electrode for an all-solid-state battery is provided, wherein the surface coating layer comprises a lithium ion conductive oxide.

[0028] In one embodiment of the present invention, the lithium ion conductive oxide is LiNbO3, Li4Ti5O 12 The present invention provides a positive electrode for an all-solid-state battery comprising one or more selected from the group consisting of Li3PO4.

[0029] In one embodiment of the present invention, a positive electrode for an all-solid-state battery is provided, wherein the average resistance (log(R / Ω)) of the positive electrode active material region is 8 or less.

[0030] In one embodiment of the present invention, the anode may be a dry anode. The dry anode refers to an anode manufactured by a dry process that does not use a solvent.

[0031]

[0032] The present invention also comprises the step of (S1) mixing a positive active material, a sulfide-based solid electrolyte, a conductive material, and a binder;

[0033] (S2) A step of fiberizing the binder by applying a shear force to the mixture obtained in step (S1) above; and

[0034] (S3) A step of obtaining an anode active material layer by performing a sheeting and calendering process using the mixture obtained in step (S2); comprising,

[0035] The present invention provides a method for manufacturing a positive electrode for an all-solid-state battery, wherein the conductive material is included in an amount of 0.1 weight% or more based on the total weight of the positive electrode active material layer.

[0036] In one embodiment of the present invention, a method for manufacturing an anode for an all-solid-state battery is provided, wherein the shear force is applied by an agate mortar, a ball mill, a kneader, or a roll press.

[0037] In one embodiment of the present invention, a method for manufacturing a positive electrode for an all-solid-state battery is provided, wherein the calendering process is performed 6 to 10 times.

[0038] In one embodiment of the present invention, a method for manufacturing a positive electrode for an all-solid-state battery is provided, wherein the calendering process is performed uniaxially or biaxially.

[0039]

[0040] The present invention also provides an all-solid-state battery comprising an anode, a cathode, and a sulfide-based solid electrolyte membrane interposed between them.

[0041] According to the cathode for an all-solid-state battery of the present invention, the electronic conductivity within the cathode can be improved by controlling the content of the conductive material during cathode manufacturing, and accordingly, various resistances are reduced and the performance of the battery is improved.

[0042] In addition, since the anode for an all-solid-state battery of the present invention also includes a fibrous binder, the ion conductivity can also be improved by controlling the porosity of the anode.

[0043] FIG. 1 is a schematic diagram of an anode to explain the relative degree of fiberization of an anode according to one embodiment of the present invention.

[0044] Figure 2 shows a cross-sectional image of the anode obtained by Scanning Spreading Resistance Microscopy (SSRM) analysis of the diffusion resistance of Example 1, Example 2, and Comparative Example 1.

[0045] Figure 3 shows the resistance of the cathode active material as a histogram, confirmed from cross-sectional photographs of the cathode obtained by SSRM analysis of Example 1, Example 2, and Comparative Example 1.

[0046] Hereinafter, the present invention will be described in more detail to aid in understanding the invention.

[0047] Terms and words used in this specification and claims should not be interpreted as being limited to their ordinary or dictionary meanings, but should be interpreted in a meaning and concept consistent with the technical spirit of the invention, based on the principle that the inventor can appropriately define the concept of the terms to best describe his invention.

[0048] As used in this specification, the term “degree of fibrosis” refers to the extent to which a material has progressed into a fibrous state. Specifically, it means that the greater the aspect ratio as the binder becomes fibrous, the greater the degree of fibrosis.

[0049] The term “relative degree of fibrillation of the anode” as used in this specification refers to the ratio of the degree of fibrillation of the fluorine-containing binder present on the surface of the anode active material layer to the degree of fibrillation of the fluorine-containing binder present inside the anode active material layer. Inside and on the surface of the anode active material layer, the fluorine-containing binder may exist as a fibrous binder in a fibrillated form, or as a secondary particle formed by the aggregation of multiple primary particles. If fluorine elements are detected inside and on the surface of the anode active material layer, it means that the binder exists as a secondary particle. That is, the higher the content of the fluorine element, the less the fibrillation of the binder proceeds, meaning that the binder exists more as a secondary particle. Therefore, the degree of fibrillation of the binder can be confirmed by the ratio of the content of fluorine elements detected inside and on the surface of the anode active material layer.

[0050]

[0051] cathode for all-solid-state batteries

[0052] The present invention relates to a positive electrode for an all-solid-state battery.

[0053] A positive electrode for an all-solid-state battery according to the present invention comprises a positive electrode active material layer, wherein the positive electrode active material layer comprises a positive electrode active material, a sulfide-based solid electrolyte, a conductive material, and a fibrous binder, and the conductive material may be included in an amount of 0.1 weight% or more based on the total weight of the positive electrode active material layer. The positive electrode active material layer may be formed on one surface of a positive electrode current collector. Alternatively, if the positive electrode active material layer is in a freestanding form, the positive electrode active material layer may be used as a positive electrode.

[0054]

[0055] In one embodiment of the present invention, the conductive material facilitates electron movement between materials within the positive electrode active material layer to improve conductivity and reduce resistance, thereby improving the performance of the all-solid-state battery.

[0056] The above conductive material may be 0.1 wt% or more based on the total weight of the anode active material layer. If the content of the above conductive material is less than 0.1 wt%, the degree of improvement in internal conductivity of the anode is negligible, and the resistance of the anode may increase. Specifically, the content of the above conductive material may be 0.1 wt% or more, 0.2 wt% or more, 0.3 wt% or more, 0.4 wt% or more, 0.5 wt% or more, 0.6 wt% or more, 0.7 wt% or more, 0.8 wt% or more, 0.9 wt% or more, or 1 wt% or more. Although the upper limit of the content of the above conductive material is not specifically restricted, it may be 10 wt% or less, 9 wt% or less, 8 wt% or less, 7 wt% or less, 6 wt% or less, 5 wt% or less, 4 wt% or less, 3 wt% or less, or 2 wt% or less. If the content of the above conductive material is too high, the amount of the positive active material becomes relatively small, which may lead to a decrease in capacity and energy density.

[0057] In addition, the conductive material is not particularly limited as long as it prevents adverse reactions in the internal environment of the all-solid-state battery and possesses excellent electrical conductivity without causing chemical changes in the battery. Representative examples include graphite or conductive carbon, such as graphite, natural graphite, artificial graphite, etc.; carbon black, such as acetylene black, Ketjen black, Denka black, thermal black, channel black, furnace black, lamp black, thermal black, etc.; carbon nanotubes, such as single-walled carbon nanotubes or multi-walled carbon nanotubes; carbon-based materials having a crystal structure of graphene or graphite; conductive fibers, such as carbon fibers or metal fibers; fluorinated carbon; metal powders, such as aluminum powder or nickel powder; conductive whiskies, such as zinc oxide or potassium titanate; conductive oxides, such as titanium oxide; and conductive polymers, such as polyphenylene derivatives; may be used alone or in a mixture of two or more types, but is not necessarily limited thereto.

[0058] In addition, the conductive material may be in the form of a fibrous structure with a long aspect ratio. The conductive material in the form of a fibrous structure with a long aspect ratio may be a carbon nanofiber (CNF), for example, a vapor-grown carbon fiber (VGCF). When the conductive material is in the form of a fibrous structure, the fibrous conductive materials are connected to each other within the anode to form a conductive network, which may be more advantageous for improving electronic conductivity.

[0059] In addition, among the fibrous conductive materials, the length of the fibrous conductive material is 5 μm to 30 μm and the diameter of the cross-section is 100 nm to 500 nm, which may be more advantageous for improving electronic conductivity. Specifically, the length of the fibrous conductive material may be 5 μm or more, 6 μm or more, 7 μm or more, 8 μm or more, 9 μm or more, 10 μm or more, 11 μm or more, 12 μm or more, or 13 μm or more, and may be 30 μm or less, 29 μm or less, 28 μm or less, 27 μm or less, 26 μm or less, 25 μm or less, 24 μm or less, 23 μm or less, 22 μm or less, 21 μm or less, 20 μm or less, 19 μm or less, 18 μm or less, 17 μm or less, 16 μm or less, or 15 μm or less. In addition, the cross-sectional diameter of the fibrous conductive material may be 100 nm or more, 110 nm or more, 120 nm or more, 130 nm or more, 140 nm or more, 150 nm or more, 160 nm or more, 170 nm or more, 180 nm or more, 190 nm or more, 200 nm or more, 210 nm or more, 220 nm or more, 230 nm or more, 240 nm or more, 250 nm or more, 260 nm or more, 270 nm or more, 280 nm or more, or 290 nm or more, and 500 nm or less, 490 nm or less, 480 nm or less, 470 nm or less, 460 nm or less, 450 nm or less, 440 nm or less, 430 nm or less, 420 nm or less, 410 nm or less, 400 nm or less, 390 nm or less, 380 nm or less. It may be 370 nm or less, 360 nm or less, 350 nm or less, 340 nm or less, 330 nm or less, 320 nm or less, or 310 nm or less.

[0060] In addition, the BET specific surface area of ​​the conductive material may be 10 m² / g or less. In this case, the contact area between the conductive material and the solid electrolyte in the anode is reduced, which may be advantageous for reducing side reactions. If the BET specific surface area exceeds 10 m² / g, electrochemical side reactions may occur due to the increased contact area between the conductive material and the solid electrolyte in the anode. Specifically, the BET specific surface area of ​​the conductive material may be 10 m² / g or less, 9 m² / g or less, 8 m² / g or less, 7 m² / g or less, 6 m² / g or less, 5 m² / g or less, or 4 m² / g or less. The lower limit of the BET specific surface area of ​​the conductive material is not specifically restricted and, for example, may be greater than 0 m² / g, 1 m² / g or more, or 2 m² / g or more. The BET specific surface area may be measured and calculated by a conventional gas adsorption method or a specific surface area measuring device.

[0061] In addition, the resistance of the conductive material may be 0.025 ohm·cm or less under a pressure of 196 MPa, which may be advantageous for improving the electrical conductivity of the anode. If the resistance of the conductive material exceeds 0.025 ohm·cm, the electrical conductivity may decrease. Specifically, the resistance of the conductive material may be 0.025 ohm·cm or less, 0.024 ohm·cm or less, 0.023 ohm·cm or less, 0.022 ohm·cm or less, 0.021 ohm·cm or less, 0.02 ohm·cm or less, 0.019 ohm·cm or less, 0.018 ohm·cm or less, 0.017 ohm·cm or less, 0.016 ohm·cm or less, 0.015 ohm·cm or less, 0.014 ohm·cm or less, 0.013 ohm·cm or less, 0.012 ohm·cm or less, or 0.011 ohm·cm or less. The lower limit of the resistance of the above-mentioned conductive material is not specifically restricted, but, for example, it may be greater than 0 ohm·cm, greater than 0.001 ohm·cm, or greater than 0.005 ohm·cm. The resistance of the above-mentioned conductive material may refer to the powder resistance of the conductive material. In addition, the method of measuring the resistance of the above-mentioned conductive material is not specifically restricted as long as it is a method or device used in the industry for measuring resistance, and for example, it may be measured using a 4-point probe system.

[0062]

[0063] In one embodiment of the present invention, the fibrous binder may be a fluorine-containing fibrous binder.

[0064] The above-mentioned fluorine-containing fibrous binder implies that during anode manufacturing, a shear force is applied to the fluorine-containing binder to form fibers, and the fiberization of the binder used as a raw material is controlled by a calendering process. Generally, the binder may be included to facilitate the bonding between materials contained in the anode active material layer and / or the bonding between the anode active material layer and the anode current collector. Due to the fibrous morphological characteristics of the binder, the bonding between materials contained in the anode active material layer is further promoted, which can further reduce the porosity of the anode and also strengthen its tensile strength.

[0065] The above fluorine-containing fibrous binder may include one or more selected from the group consisting of polytetrafluoroethylene (PTFE) and copolymers containing the same. However, the binder is not limited thereto as long as its physical properties can be easily modified and fiberized by a calendering process.

[0066] In addition, the fibrous binder may be included in an amount of 0.1 to 10 weight% based on the total weight of the positive electrode active material layer. If the content of the fibrous binder is less than 0.1 weight%, the effect of improving the binding force between materials included in the positive electrode active material layer is negligible, which may result in a decrease in tensile strength, and if it exceeds 10 weight%, the ionic conductivity or electrical conductivity of the positive electrode may decrease. Specifically, the content of the fibrous binder may be 0.1 weight% or more, 0.5 weight% or more, 1 weight% or more, 2 weight% or more, 3 weight% or more, 4 weight% or more, or 5 weight% or more, and may be 10 weight% or less, 9 weight% or less, 8 weight% or less, 7 weight% or less, or 6 weight% or less.

[0067]

[0068] In one embodiment of the present invention, the relative degree of fibrillation of the anode is calculated by the following Formula 1 and may be 4 to 6:

[0069] <Equation 1>

[0070] A = Fluorine element content on the surface of the positive active material layer (F1, wt%) / Fluorine element content inside the positive active material layer (F2, wt%).

[0071] The above positive active material layer may include a fibrous binder formed by the fiberization of a binder and a binder in the form of non-fibrous secondary particles. The distribution of the fibrous binder and the binder in the form of secondary particles may differ within and on the surface of the positive active material layer. The distribution of the fibrous binder and the binder in the form of secondary particles can be determined by a dry process utilizing sheeting and calendering processes. Since the physical properties of the positive electrode and the performance of the all-solid-state battery containing the fibrous binder and the binder in the form of secondary particles vary depending on the distribution of the fibrous binder and the binder in the form of secondary particles, these distributions are defined as the relative degree of fiberization (A) of the positive electrode. Here, the secondary particles refer to particles formed by the aggregation of multiple primary particles, which are single particles.

[0072] It is preferable that the relative degree of fiberization (A) of the anode is greater in the interior than in the surface, and this corresponds to the case where A > 1. More preferably, if 4 ≤ A ≤ 6 is satisfied, the tensile strength of the anode can be strengthened while preventing an increase in resistance. Specifically, if the relative degree of fiberization (A) of the anode is less than 4, it means that the fluorine-containing binder exists more in the form of secondary particles rather than fibers within the anode active material layer, and there is a large amount of detected internal fluorine elements. This implies that the fiberization of the binder within the anode has not progressed significantly, which may result in a decrease in the tensile strength of the anode. Furthermore, if the relative degree of fiberization (A) of the anode is greater than 6, it means that the fluorine-containing binder exists more in the form of fibers rather than secondary particles within the anode active material layer, which implies that the fiberization of the binder within the anode has progressed significantly. While the tensile strength of the anode may increase, the performance of the all-solid-state battery may be degraded because the resistance component increases due to excessive fiberization. Specifically, the relative degree of fibrosis (A) of the anode may be 4 or more, 4.1 or more, 4.2 or more, 4.3 or more, 4.4 or more, 4.5 or more, 4.6 or more, 4.7 or more, 4.8 or more, 4.9 or more, or 5 or more, and may be 6 or less, 5.9 or less, 5.8 or less, 5.7 or less, 5.6 or less, 5.5 or less, 5.4 or less, 5.3 or less, 5.2 or less, or 5.1 or less.

[0073] The content of fluorine elements on the surface of the positive active material layer (F1, wt%) and the content of fluorine elements inside the positive active material layer (F2, wt%) can be measured by energy-dispersive X-ray spectroscopy (EDS). Specifically, (a) after analyzing the interior and surface of the positive active material layer by EDS, (b) the content of fluorine elements on the surface of the positive active material layer (F1, wt%) and the content of fluorine elements inside the positive active material layer (F2, wt%) can be measured.

[0074]

[0075] FIG. 1 is a schematic diagram of an anode to explain the relative degree of fibrillation of an anode according to one embodiment of the present invention.

[0076] Referring to FIG. 1, the first region corresponds to the surface of the positive active material layer, and the second region may correspond to the interior of the positive active material layer.

[0077] The interior of the anode active material layer refers to a portion of the anode cut from the surface by a certain thickness (D). For example, the certain thickness (D) may mean 20% to 40% based on the total thickness of the anode. Specifically, the certain thickness (D) may be 20% or more, 21% or more, 22% or more, 23% or more, 24% or more, 25% or more, 26% or more, 27% or more, 28% or more, 29% or more, or 30% or more based on the total thickness of the anode, and may be 40% or less, 39% or less, 38% or less, 37% or less, 36% or less, 35% or less, 34% or less, 33% or less, 32% or less, or 31% or less.

[0078]

[0079] In one embodiment of the present invention, the sulfide-based solid electrolyte may include a compound represented by the following chemical formula 1:

[0080] <Chemical Formula 1>

[0081] Li a M b SX c

[0082] In the above chemical formula 1, M is selected from P, Sn, Sb, As, and Ge;

[0083] X is selected from Cl, Br, and I;

[0084] 5≤a<7.5, 0.5 <b<1.5, 및 0.5<c<2이다.

[0085] In addition, the sulfide-based solid electrolyte may be included in an amount of 10 to 50 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 weight% or more, 20 weight% or more, or 30 weight% or more, and may be 50 weight% or less, 45 weight% or less, or 40 weight% or less. If the content of the sulfide-based solid electrolyte is less than 10 weight%, it may not be sufficient to fill the voids formed within the positive electrode active material layer, making it difficult to reduce the porosity of the positive electrode active material; if it exceeds 50 weight%, the content of the positive electrode active material, fibrous binder, or conductive material may decrease relatively, thereby degrading the performance of the all-solid-state battery.

[0086]

[0087] In one embodiment of the present invention, 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, the positive electrode active material may be lithium cobalt oxide (LiCoO2), lithium nickel oxide (LiNiO2), Li[Ni x Co y Mn z M v ]O2(wherein M is any one element selected from the group consisting of Al, Ga, and In, or two or more of these; 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 one or more selected from the group consisting of Mn, Ni, Co, Fe, Cr, V, Cu, Zn, and Ti; M' is one or more selected from the group consisting of Al, Mg, and B, and A is one or more 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, etc.; lithium copper oxide (Li2CuO2); vanadium oxides such as LiV3O8, LiFe3O4, V2O5, Cu2V2O7, etc.; chemical formula LiNi 1-y Ni-site type 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 y Examples include lithium manganese complex oxides represented by 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 of the chemical formula is substituted with alkaline earth metal ions; disulfide compounds; Fe2(MoO4)3, but are not limited to these.

[0088] In addition, the positive active material may be included in an amount of 55 to 90 weight% based on the total weight of the positive active material layer. Specifically, the content of the positive active material may be 55 weight%, 60 weight% or more, or 65 weight% or more, and may be 83 weight% or less, 85 weight% or less, or 90 weight% or less. If the content of the positive active material is less than 55 weight%, battery performance may be degraded, and if it exceeds 90 weight%, the mass transfer resistance may increase.

[0089] In addition, the positive electrode active material may include a surface coating layer. The surface coating layer may include a lithium ion conductive oxide. When a surface coating layer including a lithium ion conductive oxide is formed on the surface of the positive electrode active material, direct contact between the positive electrode active material and the sulfide-based solid electrolyte is prevented, thereby preventing the decomposition reaction of the sulfide-based solid electrolyte.

[0090] The above lithium ion conductive oxide is LiNbO3, Li4Ti5O 12 It may include one or more selected from the group consisting of and Li3PO4. In addition, the lithium ion conductive oxide may be amorphous or crystalline. Furthermore, the method of forming a surface coating layer containing the lithium ion conductive oxide may be spray coating, immersion method, etc., but is not limited thereto, and various methods for forming a coating layer on the surface of the positive electrode active material may be used.

[0091]

[0092] In one embodiment of the present invention, the anode active material layer may have reduced porosity, reduced thickness, improved tensile strength, and reduced interfacial resistance depending on the control of the anode fiberization degree as described above. In this case, the interfacial resistance may refer to the interfacial resistance between the anode active material layer and the anode current collector, or between the anode active material layer and the sulfide-based solid electrolyte membrane.

[0093] The porosity of the positive electrode active material layer may be 11% to 15%. If the porosity exceeds 15%, the energy density of the all-solid-state battery may decrease. Specifically, the above porosity may be 11% or more, 11.1% or more, 11.2% or more, 11.3% or more, 11.4% or more, 11.5% or more, 11.6% or more, 11.7% or more, 11.8% or more, 11.9% or more, 12% or more, 12.1% or more, 12.2% or more, 12.3% or more, 12.4% or more, 12.5% ​​or more, 12.6% or more, 12.7% or more, 12.8% or more, 12.9% or more, 13% or more, and 15% or less, 14.9% or less, 14.8% or less, 14.7% or less, 14.6% or less, 14.5% or less, 14.4% or less, 14.3% or less, 14.2% or less, It may be 14.2% or less, 14.1% or less, or 14% or less. The above porosity may refer to the volume (vol%) of the pores relative to the total volume of the positive active material layer. Additionally, if the above positive active material layer itself is used as the positive without using the above positive current collector, the porosity of the above positive active material layer may refer to the porosity of the positive active material layer.

[0094] In addition, the thickness of the anode including the anode active material layer after rolling may be 120 μm or less. If the thickness exceeds 120 μm, it may act as a resistance during battery operation. The energy density of the all-solid-state battery utilizing the anode may decrease. Specifically, the thickness may be 120 μm or less, 115 μm or less, 110 μm or less, 105 μm or less, 100 μm or less, 95 μm or less, 90 μm or less, 85 μm or less, or 80 μm or less. Although the lower limit of the thickness is not specifically limited, it may be 50 μm or more, 55 μm or more, 60 μm or more, or 65 μm or more.

[0095]

[0096] In addition, the interface resistance may be 60 ohm·cm² or less. If the interface resistance exceeds 60 ohm·cm², the electrical conductivity within the anode may decrease and the charge / discharge performance may be reduced. Specifically, the interface resistance may be 60 ohm·cm² or less, 55 ohm·cm² or less, 50 ohm·cm² or less, 45 ohm·cm² or less, 40 ohm·cm² or less, 35 ohm·cm² or less, or 30 ohm·cm² or less. The lower limit of the interface resistance is not specifically limited, but may be greater than 0 ohm·cm², 5 ohm·cm² or more, or 10 ohm·cm² or more.

[0097]

[0098] In one embodiment of the present invention, the positive current collector supports the positive active material layer and serves to transfer electrons between the external wire and the positive active material layer.

[0099] The above positive current collector is not particularly limited as long as it has high electronic conductivity without causing chemical changes in the all-solid-state battery. For example, stainless steel, aluminum, nickel, titanium, palladium, calcined carbon, stainless steel surface treated with carbon, nickel, silver, etc., and aluminum-cadmium alloy may be used as the above positive current collector.

[0100] The above positive current collector may have a fine irregular structure on its surface or adopt a three-dimensional porous structure to strengthen the bonding force with the positive active material layer. Accordingly, the above positive current collector may include various forms such as a film, sheet, foil, mesh, net, porous body, foam, nonwoven fabric, etc.

[0101]

[0102] In one embodiment of the present invention, the positive electrode active material layer may be solvent-free. That is, the positive electrode active material layer may be manufactured by a solvent-free process that does not use a solvent.

[0103] Since the above-mentioned positive active material layer does not use a solvent in the manufacturing process, the phenomenon in which the crystal structure of the sulfide-based solid electrolyte is destroyed by the solvent, thereby reducing ion conductivity, can be prevented.

[0104]

[0105] In one embodiment of the present invention, the average resistance (log(R / Ω)) of the positive active material region included in the positive electrode may be 8 or less. Specifically, the average resistance of the positive active material region may be 8 or less, 7.9 or less, 7.8 or less, 7.7 or less, 7.6 or less, or 7.5 or less. If the average resistance of the positive active material region exceeds 8, the performance of the all-solid-state battery may be degraded. At this time, the average resistance of the positive active material region can be obtained using SSRM. Generally, since SSRM analysis allows for analysis of an area of ​​approximately tens of micrometers using an Atomic Force Microscopy (AFM) tip, it is possible to measure resistance changes occurring in a positive active material region of several micrometers in size. For example, volume resistivity measurement of a positive electrode involves measuring a positive electrode of about several centimeters in size to analyze the resistance of the entire positive electrode. SSRM, however, can analyze the resistance of the actual positive active material region through analysis of a more localized area.

[0106]

[0107] According to the cathode for an all-solid-state battery of the present invention, the electronic conductivity within the cathode can be improved by controlling the content of the conductive material during cathode manufacturing, and accordingly, various resistances are reduced and the performance of the battery is improved.

[0108] In addition, the degree of fiberization of the fibrous binder included in the anode can be controlled by the calendering process during anode manufacturing, and the energy density of the all-solid-state battery is improved due to the fibrous binder with controlled fiberization.

[0109]

[0110] Method for manufacturing a positive electrode for an all-solid-state battery

[0111] The present invention also relates to a method for manufacturing a positive electrode for an all-solid-state battery.

[0112] A method for manufacturing a positive electrode for an all-solid-state battery according to the present invention comprises: (S1) mixing a positive electrode active material, a sulfide-based solid electrolyte, a conductive material, and a binder; (S2) applying a shear force to the mixture obtained in step (S1) to fiberize the binder; and (S3) performing a sheeting and calendering process using the mixture obtained in step (S2) to obtain a positive electrode active material layer; wherein the conductive material may be included in an amount of 0.1 weight% or more based on the total weight of the positive electrode active material layer.

[0113]

[0114] The specific materials, physical properties, and content of the positive electrode active material, sulfide-based solid electrolyte, conductive material, 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, so a detailed description is omitted.

[0115]

[0116] In step (S1) of the method for manufacturing a positive electrode for an all-solid-state battery according to the present invention, a positive electrode active material, a sulfide-based solid electrolyte, a conductive material, and a binder may be mixed.

[0117] The above-mentioned cathode active material, sulfide-based solid electrolyte, conductive material, and binder used as raw materials are all in powder form, and can be uniformly mixed considering processability and product reliability. The mixing method is not particularly limited as long as it is a method capable of uniformly mixing powder-form materials. The above-mentioned binder refers to the raw material for the fibrous binder included in the cathode for the all-solid-state battery described above.

[0118]

[0119] In step (S2) of the method for manufacturing a positive electrode for an all-solid-state battery according to the present invention, a shear force can be applied to the mixture obtained in step (S1) to fiberize the binder.

[0120] Due to the shear force described above, the binder contained in the mixture may be physically deformed and fiberized. As previously mentioned, the binder used as a raw material may possess physical properties that allow it to be easily deformed. Furthermore, to apply a shear force to the mixture, the mixture may be introduced into a mortar, ball mill, kneader, or roll press to perform physical mixing. During physical mixing, the shear force applied to the binder causes it to frictionally rub against the powder particles within the mixture, thereby physically deforming and fiberizing.

[0121]

[0122] In step (S3) of the method for manufacturing a positive electrode for an all-solid-state battery according to the present invention, a positive electrode active material layer can be obtained by performing a sheeting and calendering process using the mixture obtained in step (S2). At this time, the mixture obtained in step (S2) may be used as is, or the mixture may be ground before use.

[0123] The above sheeting process is a step of initially forming a mixture containing a fiberized binder from step (S1) into a film shape. Additionally, the above calendering process can further roll the film-shaped molded product to control the degree of fiberization of the binder and control the porosity, thickness, or tensile strength of the anode active material layer. Furthermore, due to the above sheeting and calendering processes, the anode active material layer can be formed into a film shape in which physical properties such as the degree of fiberization, porosity, thickness, or tensile strength of the binder are controlled.

[0124]

[0125] In one embodiment of the present invention, the calendering process enables control of the porosity, thickness, and tensile strength of the anode active material layer. The calendering process refers to a process of passing a workpiece between two rollers.

[0126] The above calendering process may be performed 6 to 10 times. In this case, the number of calendering processes may refer to the number of times the workpiece passes between the two rollers. If the number of calendering processes is less than 6 times, the effect of reducing the thickness and porosity of the anode active material layer and the effect of improving tensile strength may be negligible, and if it exceeds 10 times, processability may be reduced. Specifically, the process may be 6 times or more or 7 times or more, and 10 times or less, 9 times or less, or 8 times or less.

[0127]

[0128] In one embodiment of the present invention, the orientation of the calendering process may be performed uniaxially or biaxially. Herein, uniaxial means that the calendering proceeds in one direction, and biaxial means that after calendering proceeds in one direction, it proceeds alternately in the horizontal plane and the vertical direction of the anode active material layer.

[0129] When the above calendering process is performed uniaxially, the fiberization of the binder becomes directional. On the other hand, when the above calendering process is performed biaxially, the fiberization of the binder becomes uniformly directional, so the difference in strength according to direction can be reduced.

[0130]

[0131] In the method for manufacturing a positive electrode for an all-solid-state battery according to the present invention, if the positive electrode active material layer is not in a freestanding form, the method may further include the step of attaching the positive electrode active material layer in a film form obtained in the step (S3) to a positive electrode current collector as the step (S4), thereby manufacturing a positive electrode for an all-solid-state battery.

[0132] The type and physical properties of the above-mentioned positive current collector are as described above.

[0133]

[0134] All-solid-state battery

[0135] The present invention also relates to an all-solid-state battery comprising the anode.

[0136] The all-solid-state battery according to the present invention comprises the anode, the cathode, and a sulfide-based solid electrolyte membrane interposed between them. The anode is as described above.

[0137]

[0138] In one embodiment of the present invention, the cathode includes a cathode active material layer, and the cathode active material layer may be formed on one surface of a cathode current collector.

[0139] The above-mentioned cathode active material layer may include a cathode active material, a conductive material, and a binder. Alternatively, the above-mentioned cathode active material layer may be an anodeless layer.

[0140] In addition, in the above-mentioned negative electrode active material layer, the negative electrode active material is lithium (Li + It may include a material capable of reversibly intercalating or deintercalating ), a material capable of reacting with lithium ions to reversibly form a lithium-containing compound, a lithium metal, or a lithium alloy.

[0141] The above lithium ion (Li + A material capable of reversibly inserting or deinserting ) may be, for example, crystalline carbon, amorphous carbon, or a mixture thereof. The lithium ions (Li +A material capable of reversibly forming 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 a metal selected from the group consisting of lithium (Li) and 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).

[0142] Preferably, the negative electrode active material may be lithium metal or lithium-indium alloy (Li-In), and specifically, may be in the form of a thin film or a lithium-indium alloy thin film or powder with lithium metal or lithium.

[0143] The above-mentioned negative electrode active material may be included in an amount of 40 to 80 weight% based on the total weight of the negative electrode active material layer. Specifically, the content of the above-mentioned negative electrode active material may be 40 weight% or more or 50 weight% or more, and 70 weight% or less or 80 weight% or less. If the content of the above-mentioned negative electrode active material is less than 40 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 weight%, the mass transfer resistance may increase.

[0144] In addition, the above binder is a component that assists in the bonding of the negative electrode active material and the conductive material, etc., and in the bonding to the negative electrode current collector, and comprises styrene-butadiene rubber, acrylated styrene-butadiene rubber, acrylonitrile copolymer, acrylonitrile-butadiene rubber, nitrile butadiene rubber, acrylonitrile-styrene-butadiene copolymer, acrylic rubber, butyl rubber, fluorine rubber, polytetrafluoroethylene, 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, hydroxypropyl cellulose, cellulose acetate, and cellulose acetate. It may include one or more selected from the group consisting of 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)-hexafluoropropene. Preferably, the binder may include polytetrafluoroethylene (PTFE).

[0145] Additionally, 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 content of the binder may be 0.5% by weight or more, 1% by weight or more, or 1.5% by weight or more, and 3% by weight or less, 3.5% by weight or less, or 4% by weight or less. If the content of the binder is less than 0.5% by weight, the adhesion between the positive electrode active material and the negative electrode current collector may decrease, and if it exceeds 4% by weight, the adhesion improves, but the content of the negative electrode active material decreases accordingly, which may result in a lower battery capacity.

[0146]

[0147] In addition, the conductive material is not particularly limited as long as it prevents side reactions in the internal environment of the all-solid-state battery and possesses excellent electrical conductivity without causing chemical changes in the battery. Representative examples include graphite or conductive carbon. For instance, 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, or thermal black; carbon-based materials having a crystal structure of graphene or graphite; conductive fibers such as carbon fibers or metal fibers; fluorocarbon; metal powders such as aluminum powder or nickel powder; conductive whiskies such as zinc oxide or potassium titanate; conductive oxides such as titanium oxide; and conductive polymers such as polyphenylene derivatives may be used alone or in a mixture of two or more types, but is not necessarily limited thereto. Preferably, the conductive material may include vapor-grown carbon fiber (VGCF).

[0148] The conductive material may typically be included 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, and 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), it is difficult to expect an improvement in electrical conductivity or the electrochemical properties of the battery may deteriorate; if it is too high (more than 5% by weight), the amount of the negative electrode active material becomes relatively small, which may lead to a decrease in capacity and energy density. The method of including the conductive material in the negative electrode is not significantly limited, and conventional methods known in the art, such as mixing with the negative electrode active material or coating, may be used.

[0149] In addition, the above negative current collector is not particularly limited as long as it is conductive without causing chemical changes in the battery. For example, the above negative current collector may be copper, stainless steel, aluminum, nickel, titanium, calcined carbon, copper or stainless steel surface treated with carbon, nickel, titanium, silver, etc., or aluminum-cadmium alloy. In addition, the above negative current collector may be used in various forms such as a film, sheet, foil, net, porous body, foam, or nonwoven fabric having fine irregularities formed on its surface, just like the positive current collector.

[0150] The method of manufacturing the above-mentioned cathode is not particularly limited, and it can be manufactured by forming a cathode active material layer on a cathode current collector using a method of forming a layer or film commonly used in the industry. For example, methods such as compression, coating, or deposition may be used. Furthermore, the cathode of the present invention includes cases where a metallic lithium thin film is formed on a metal plate by initial charging after the battery is assembled without a lithium thin film on the cathode current collector.

[0151]

[0152] In addition, the above-mentioned non-cathode layer refers to a negative electrode layer in which, at the time of the initial assembly of the battery, lithium metal or lithium alloy, which can serve as a lithium source among the negative electrode active materials, is not present in the negative electrode, but lithium is precipitated in the negative electrode upon charging. A battery comprising the above-mentioned non-cathode layer can be called a negative electrode-free battery.

[0153] In the above-described negative electrode-free battery, lithium ions emitted from the positive electrode move to the negative electrode to form a negative electrode active material layer during the charging and discharging of the battery. For example, when charging the battery, lithium ions are detached from the positive electrode active material and move toward the negative electrode side to form a lithium metal composed purely of lithium, which may form a lithium metal layer in the form of a layer on the negative electrode current collector, or form a lithium metal structure in any shape other than a layer. Any shape may be, for example, a structure in which lithium metal is aggregated into a particle shape.

[0154]

[0155] In one embodiment of the present invention, the sulfide-based solid electrolyte included in the sulfide-based solid electrolyte membrane may be represented by the following chemical formula 1:

[0156] <Chemical Formula 1>

[0157] Li a M b SX c

[0158] In the above chemical formula 1, M is selected from P, Sn, Sb, As, and Ge;

[0159] X is selected from Cl, Br, and I;

[0160] 5≤a<7.5, 0.5 <b<1.5, 및 0.5<c<2이다.

[0161] However, the above sulfide-based solid electrolytes are not limited to these, and sulfide-based solid electrolytes commonly used in the industry may be widely used.

[0162]

[0163] battery module

[0164] The present invention also relates to a battery module comprising the all-solid-state battery as a unit cell, a battery pack comprising the battery module, and a device comprising the battery pack as a power source.

[0165] Specific examples of the above-mentioned device include, but are not limited to, power tools that are powered by an electric motor; electric vehicles including electric vehicles (EV), hybrid electric vehicles (HEV), plug-in hybrid electric vehicles (PHEV); electric two-wheeled vehicles including electric bicycles (E-bike) and electric scooters (E-scooter); electric golf carts; and power storage systems.

[0166] Preferred embodiments are presented below to aid in understanding the present invention; however, the following embodiments are merely illustrative of the invention, and it is obvious to those skilled in the art that various changes and modifications are possible within the scope and spirit of the invention, and that such changes and modifications fall within the scope of the appended claims.

[0167]

[0168] In the following examples and comparative examples, a positive electrode and an all-solid-state battery containing the same were manufactured according to the composition of the positive electrode active material layer as described in Table 1 below.

[0169]

[0170] Composition of positive electrode active material layer (weight%) Positive electrode active material Sulpide-based solid electrolyte Conductor binder Example 17819.511.5 Example 27820.30.21.5 Comparative Example 17820.501.5

[0171]

[0172] Example 1

[0173] 1-1. Anode Manufacturing

[0174] LiN as a positive active material 0.8 Co 0.1 Mn 0.1 An anode was prepared as follows using O2 (NCM 811), Li6PS5Cl as a sulfide-based solid electrolyte, vapor-grown carbon fiber (VGCF) as a conductive material, and polytetrafluoroethylene (PTFE) as a binder.

[0175] Powder mixing was performed using a positive electrode active material, a sulfide-based solid electrolyte, a conductive material, and a binder in a weight ratio of 78:19.5:1:1.5. Specifically, the positive electrode active material and the sulfide-based solid electrolyte were measured in powder form and mixed using a blade mixer in a dry room environment. Subsequently, a measured amount of the conductive material was added and mixed further. Then, a measured amount of the binder was added and mixed further to obtain a mixture.

[0176] The above mixture was fed into a mortar and pestle, and the binder contained in the mixture was fiberized using the mortar. Afterward, the mixture was passed between two rollers to perform sheeting, and then rolled through a calendering process to obtain a film-shaped cathode active material layer. The calendering process was performed six times.

[0177]

[0178] Example 2

[0179] A cathode was prepared in the same manner as in Example 1, except that the cathode active material, sulfide-based solid electrolyte, conductive material, and binder were in a weight ratio of 78:20.3:0.2:1.5.

[0180]

[0181] Comparative Example 1

[0182] An anode was prepared in the same manner as in Example 1, except that no conductive material was used.

[0183]

[0184] Experimental Example 1: Evaluation of Anode Properties According to Conductive Material Content

[0185] The physical properties of the anode according to the content of the conductive material included in the anode active material layer were evaluated as follows.

[0186]

[0187] (1) Measurement of resistance in the positive active material region

[0188] After manufacturing the anode, a Warm Isostatic Press (WIP) was performed to increase the anode density, and then an anode specimen was fabricated using Ar ion milling and mounted on an Atomic Force Microscope (AFM) located inside a glove box. Scanning Spreading Resistance Microscopy (SSRM) measurements based on contact mode were performed on the anode specimen using a conductive diamond probe. From the log(R / Ω) images obtained therefrom, the pixel values ​​of the anode active material region were extracted to calculate the average and deviation of the anode active material resistance.

[0189] Dimension Icon is the equipment used for SSRM measurement. ® A Bruker diamond-coated silicon cantilever was used.

[0190]

[0191] (2) Anode resistance measurement - Multi probe

[0192] After punching the anodes to a specific size, they were placed in contact with the current collector, packaged, and subjected to Warm Isostatic Pressing (WIP). Subsequently, the volume resistivity of the anodes inside the packaging was observed using an electrode resistance measurement system (RM2610, Hioki).

[0193]

[0194] Table 2 below shows the average and deviation of the cathode active material resistance calculated from the SSRM analysis results, and the measured volume resistance of the cathode.

[0195]

[0196] Example 1 Example 2 Comparative Example 1 Average of anode active material resistance (log(R / Ω)) 7.43 7.67 8.2 Deviation of anode active material resistance (log(R / Ω)) 0.63 0.61 0.68 Anode volume resistance (ohm·cm) 3300 5600 9500

[0197]

[0198] As shown in Table 2 above, Comparative Example 1, which did not use a conductive material in the anode, showed large average and deviation resistances of the anode active material and large volume resistance of the anode.

[0199] Accordingly, it can be seen that using an appropriate amount of conductive material in the anode is advantageous for reducing resistance. In addition, in Example 1 and Example 2, which contain a conductive material in the anode, it was confirmed that in Example 1, where the content of the conductive material is relatively large, the average and deviation of the resistance of the anode active material are small, and the volume resistance of the anode is also small.

[0200]

[0201] Figure 2 shows a cross-sectional photograph of the anode obtained by SSRM analysis of Example 1, Example 2 and Comparative Example 1, and Figure 3 shows a histogram of the resistance of the anode active material confirmed from the cross-sectional photograph of the anode obtained by SSRM analysis of Example 1, Example 2 and Comparative Example 1.

[0202]

[0203] In Fig. 2, as we move from Example 1 to Example 2 and Comparative Example 1, the content of the conductive material in the anode decreases, and the blue color changes to sky blue and green. In Fig. 3, it was shown that the average resistance of the anode active material increased as we move from Example 1 to Example 2 and Comparative Example 1.

[0204] Therefore, it can be seen in Figure 2 that the average resistance of the positive active material increases as it changes to blue, sky blue, and green.

Claims

1. A cathode for an all-solid-state battery having a cathode active material layer comprising a cathode active material, a sulfide-based solid electrolyte, a conductive material, and a fibrous binder, A positive electrode for an all-solid-state battery, wherein the conductive material is included in an amount of 0.1 weight% or more based on the total weight of the positive electrode active material layer.

2. In Paragraph 1, A cathode for an all-solid-state battery, wherein the conductive material comprises one or more selected from the group consisting of graphite, carbon black, carbon nanotube, carbon fiber, and graphene.

3. In Paragraph 1, The above fibrous binder is a fluorine-containing fibrous binder, and A positive electrode for an all-solid-state battery, wherein the above-mentioned fluorine-containing fibrous binder comprises one or more selected from the group consisting of polytetrafluoroethylene (PTFE) and copolymers containing the same.

4. In Paragraph 1, A positive electrode for an all-solid-state battery, wherein the relative degree of fibrillation (A) of the above positive electrode is calculated by the following Equation 1 and is 4 to 6: <Equation 1> A = Fluorine element content on the surface of the positive active material layer (F1, wt%) / Fluorine element content inside the positive active material layer (F2, wt%).

5. In Paragraph 1, A positive electrode for an all-solid-state battery, wherein the above positive active material comprises a surface coating layer.

6. In Paragraph 5, A positive electrode for an all-solid-state battery, wherein the above surface coating layer comprises a lithium ion conductive oxide.

7. In Paragraph 6, The above lithium ion conductive oxide is LiNbO3, Li4Ti5O 12 A positive electrode for an all-solid-state battery comprising one or more selected from the group consisting of and Li3PO4.

8. In Paragraph 1, A positive electrode for an all-solid-state battery, wherein the average resistance (log(R / Ω)) of the positive electrode active material region is 8 or less.

9. (S1) A step of mixing a positive electrode active material, a sulfide-based solid electrolyte, a conductive material, and a binder; (S2) A step of fiberizing the binder by applying a shear force to the mixture obtained in step (S1) above; and (S3) A step of obtaining an anode active material layer by performing a sheeting and calendering process using the mixture obtained in step (S2); comprising, A method for manufacturing a positive electrode for an all-solid-state battery, wherein the conductive material is included in an amount of 0.1 weight% or more based on the total weight of the positive electrode active material layer.

10. In Paragraph 9, A method for manufacturing a positive electrode for an all-solid-state battery, wherein the above shear force is applied by a mortar, ball milling, a kneader, or a roll press.

11. In Paragraph 9, A method for manufacturing a positive electrode for an all-solid-state battery, wherein the above calendering process is performed 6 to 10 times.

12. In Paragraph 9, A method for manufacturing a positive electrode for an all-solid-state battery, wherein the above calendering process is performed uniaxially or biaxially.

13. An all-solid-state battery comprising the anode and cathode of claim 1 and a sulfide-based solid electrolyte membrane interposed between them.

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