Positive electrode active material for all-solid-state battery, positive electrode comprising same for all-solid-state battery, and all-solid-state battery

Abstract

The present invention relates to a positive electrode active material for an all-solid-state battery, a positive electrode comprising same for an all-solid-state battery, and an all-solid-state battery. More specifically, a coating layer containing an oxysulfide-based solid electrolyte formed on the positive electrode active material prevents a side reaction between the positive electrode active material and solid electrolyte particles in the positive electrode, leading to improved output characteristics and lifespan characteristics of the all-solid-state battery.

Description

A positive electrode active material for an all-solid-state battery, a positive electrode for an all-solid-state battery including the same, and an all-solid-state battery

[0001] Cross-citation with related applications

[0002] The present application claims the benefit of priority based on Korean Patent Application No. 10-2024-0149344 filed October 29, 2024 and Korean Patent Application No. 10-2025-0159287 filed October 29, 2025, and all contents disclosed in the documents of said Korean patent applications are incorporated into this specification.

[0003] Technology field

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

[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, such as 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] 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 they do not use flammable solvents 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 possess high ionic conductivity of the solid electrolyte and can theoretically achieve a high energy density of over 900 Wh / L. 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 due to the liquid electrolyte contained in conventional lithium-ion batteries (LIBs). Therefore, when manufacturing a cathode for a sulfide-based all-solid-state battery, 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 increasing the ionic conductivity of lithium ions.

[0009] However, a chemical reaction occurs at the interface between the positive active material and the sulfide-based solid electrolyte particles merely through physical contact due to their level difference. A resistive material may be formed by this chemical reaction. Due to this resistive material, the initial capacity and long-life characteristics of the all-solid-state battery may be degraded during operation.

[0010] In addition, during charging and discharging, an electrochemical reaction occurs at the interface between the positive electrode active material and the sulfide-based solid electrolyte particles, which can not only consume active lithium but also increase resistance.

[0011] Therefore, there is a need for the development of technology that can improve the output and lifespan characteristics of all-solid-state batteries by preventing side reactions at the interface between the positive electrode active material and sulfide-based solid electrolyte particles.

[0012] [Prior Art Literature]

[0013] (Patent Document 1) Korean Published Patent No. 10-2023-0031939

[0014] As a result of conducting multifaceted research to solve the above problem, the inventors confirmed that forming a coating layer containing an oxalate-sulfide-based solid electrolyte on the surface of the positive electrode active material can prevent side reactions between the positive electrode active material and solid electrolyte particles within the positive electrode.

[0015] Accordingly, the objective of the present invention is to provide a positive electrode active material for an all-solid-state battery having a coating layer formed thereon comprising an oxalate-based solid electrolyte.

[0016] Another objective of the present invention is to provide a positive electrode for an all-solid-state battery comprising a positive electrode active material having a coating layer formed thereon comprising an oxalate-based solid electrolyte.

[0017] Another objective of the present invention is to provide an all-solid-state battery comprising a positive electrode comprising a positive electrode active material having a coating layer formed thereon comprising an oxalate-based solid electrolyte.

[0018] To achieve the above objective, the present invention provides a positive electrode active material for an all-solid-state battery comprising: a core particle; and a coating layer located on the surface of the core particle, wherein

[0019] The above coating layer provides a positive electrode active material for an all-solid-state battery, wherein the coating layer comprises an oxysulfide-based solid electrolyte.

[0020] In one embodiment of the present invention, the oxosulfide-based solid electrolyte comprises oxygen (O) and sulfur (S) in a weight ratio of 0.02:1 to 0.1:1, thereby providing a positive electrode active material for an all-solid-state battery.

[0021] In one embodiment of the present invention, a positive electrode active material for an all-solid-state battery is provided, wherein the oxysulfide-based solid electrolyte is represented by the following chemical formula 1:

[0022] <Chemical Formula 1>

[0023] Li (7-x) PS (6-x-y) O y Ha x

[0024] In the above chemical formula 1, Ha is Cl, Br, or I, 0 < x < 1.6, and 0.1 < y < 1.

[0025] In one embodiment of the present invention, the positive electrode active material for an all-solid-state battery is provided, wherein the oxysulfide-based solid electrolyte has an azirodite-type crystal structure.

[0026] In one embodiment of the present invention, a positive electrode active material for an all-solid-state battery is provided, wherein the oxalate-based solid electrolyte is included in an amount of 0.1% to 2% by weight based on the total weight of the positive electrode active material.

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

[0028] In one embodiment of the present invention, a positive electrode active material for an all-solid-state battery is provided, wherein the coating layer comprises a first coating layer comprising a lithium metal oxide and a second coating layer comprising an oxalate-sulfide-based solid electrolyte.

[0029] In one embodiment of the present invention, a positive electrode active material for an all-solid-state battery is provided, wherein the residual lithium content in the positive electrode active material is 3000 ppm or more.

[0030] In one embodiment of the present invention, a positive electrode active material for an all-solid-state battery is provided, wherein the core particle is in the form of a multi-particle structure formed by the aggregation of a plurality of single particles of a positive electrode active material.

[0031] In one embodiment of the present invention, a positive electrode active material for an all-solid-state battery is provided, wherein the plurality of single particles are aggregated with orientation.

[0032] In one embodiment of the present invention, a positive electrode active material for an all-solid-state battery is provided, wherein the aspect ratio of the single particles is 0.05:1 to 0.5:1.

[0033] In one embodiment of the present invention, a positive electrode active material for an all-solid-state battery is provided, wherein the particle size (D50) of the positive electrode active material is 3.3 μm to 6.3 μm.

[0034] In one embodiment of the present invention, a positive electrode for an all-solid-state battery is provided, comprising the positive electrode active material, solid electrolyte particles, binder, and conductive material.

[0035] In one embodiment of the present invention, a solid-state battery including the positive electrode is provided.

[0036] According to the present invention, due to a coating layer comprising an oxide sulfide-based solid electrolyte formed on the surface of a positive electrode active material for an all-solid-state battery, side reactions at the interface between the positive electrode active material and solid electrolyte particles within the positive electrode are prevented, and as a result, the output characteristics and lifespan characteristics of the all-solid-state battery can be improved.

[0037] FIG. 1 is a schematic diagram of a positive electrode active material for an all-solid-state battery according to one embodiment of the present invention.

[0038] Hereinafter, the present invention will be described in more detail to aid in understanding the invention.

[0039] 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.

[0040] As used in this specification, the term “anode active material” refers to an active material that generates electrical energy at the anode and serves to provide lithium ions to the cathode during charging. In other words, while the “anode active material” generally refers to a commonly used anode active material, in this specification, the anode active material has a structure comprising a core particle and a coating layer formed on the surface of the core particle; therefore, the active material contained within the core particle is referred to as an anode active material to distinguish it from the anode active material.

[0041]

[0042] Cathode active material for all-solid-state batteries

[0043] The present invention relates to a positive electrode active material for an all-solid-state battery.

[0044] A positive electrode active material for an all-solid-state battery according to the present invention comprises a core particle; and a coating layer located on the surface of the core particle, wherein the coating layer comprises an oxysulfide-based solid electrolyte.

[0045] In one embodiment, the core particle may include a positively active material.

[0046] In one embodiment, a coating layer containing an oxalate-based solid electrolyte is formed on the surface of the core particle. Due to the coating layer, side reactions between the positive electrode active material and the solid electrolyte particle can be prevented within the positive electrode, specifically within the positive electrode active material layer. Specifically, at the interface between the positive electrode active material and the solid electrolyte particle, the solid electrolyte particle comes into contact with the coating layer formed on the positive electrode active material. When the core particle containing the positive electrode active material and the solid electrolyte particle come into direct contact, side reactions such as chemical and / or electrochemical reactions may occur due to the difference in energy levels. Interfacial degradation may occur due to such side reactions, which may degrade battery performance. However, when the coating layer containing the oxalate-based solid electrolyte comes into direct contact with the solid electrolyte particle, side reactions between the core particle containing the positive electrode active material and the solid electrolyte particle are prevented, thereby improving the output characteristics and lifespan characteristics of the all-solid-state battery.

[0047]

[0048] In one embodiment of the present invention, the oxosulfide-based solid electrolyte is a solid electrolyte comprising oxygen (O) and sulfur (S), and may comprise oxygen (O) and sulfur (S) in a weight ratio of 0.02:1 to 0.1:1.

[0049] If the weight ratio of oxygen to sulfur is less than 0.02:1 (=0.02 / 1), the oxygen content is low and may not function sufficiently as an oxosulfide, and if it exceeds 0.1:1 (=0.1 / 1), the oxygen content is high and oxides may precipitate as impurities during the synthesis of the solid electrolyte. Specifically, the weight ratio of oxygen to sulfur may be 0.02:1 or higher, 0.03:1 or higher, 0.04:1 or higher, 0.05:1 or higher, 0.06:1 or higher, or 0.07:1 or higher, and may be 0.1:1 or lower, 0.09:1 or lower, or 0.08:1 or lower.

[0050]

[0051] In one embodiment of the present invention, the oxosulfide-based solid electrolyte may be represented by the following chemical formula 1:

[0052] <Chemical Formula 1>

[0053] Li (7-x) PS (6-x-y) O y Ha x

[0054] In the above chemical formula 1, Ha is Cl, Br, or I, 0 < x < 1.6, and 0.1 < y < 1.

[0055]

[0056] In one embodiment of the present invention, the oxalate-based solid electrolyte may have an agyrodite-type crystal structure.

[0057] The above azirodite-type crystal structure refers to a face-centered cubic (FCC) crystal structure. In the above azirodite-type crystal structure, lithium ions can move quickly, so lithium ion conductivity can be improved.

[0058] In addition, the oxysulfide-based solid electrolyte with the azirodite-type crystal structure mentioned above has the advantages of being easy to synthesize and having good ion conductivity, but oxysulfide-based solid electrolytes are not limited to this, and oxysulfide-based solid electrolytes with various crystal structures applicable to all-solid-state batteries can be used.

[0059]

[0060] In one embodiment of the present invention, the oxalate-based solid electrolyte may be included in an amount of 0.1% to 2% by weight based on the total weight of the anode active material.

[0061] If the content of the oxalate-sulfide-based solid electrolyte is less than 0.1 wt%, the effect of preventing side reactions between the positive active material and the solid electrolyte particles within the positive active material layer may be reduced, and if it exceeds 2 wt%, it may act as a resistor within the battery. Specifically, the content of the oxalate-sulfide-based solid electrolyte 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, and may be 2 wt% or less, 1.9 wt% or less, 1.8 wt% or less, 1.7 wt% or less, 1.6 wt% or less, 1.5 wt% or less, 1.4 wt% or less, 1.3 wt% or less, 1.2 wt% or less, or 1.1 wt% or less.

[0062]

[0063] In one embodiment of the present invention, the coating layer may further comprise a lithium metal oxide.

[0064] The above lithium metal oxide can be represented by the following chemical formula 2:

[0065] <Chemical Formula 2>

[0066] LxMOy

[0067] In the above chemical formula 2, M is C, B, Zr, Nb, Ti, Al, W, P, or Fe, 0 < x < 5, and 0 < y < 4.

[0068] When the lithium metal oxide is included in the coating layer, the coating layer may have a double-layer structure comprising a first coating layer including the lithium metal oxide and a second coating layer including the oxysulfide-based solid electrolyte. Preferably, the lithium metal oxide may be LiNbO3.

[0069]

[0070] In one embodiment of the present invention, the content of residual lithium (Y) contained in the positive electrode active material may be 3000 ppm or more. The residual lithium is derived from the core particles and may be a byproduct after the synthesis of the core particles. The content of residual lithium is based on the entire positive electrode active material excluding the coating layer containing an oxide sulfide-based solid electrolyte in the positive electrode active material.

[0071] If the above residual lithium content (Y) is less than 3000 ppm, the overvoltage may increase during initial formation. Specifically, the above lithium content (Y) may be 3000 ppm or more, 4000 ppm or more, 5000 ppm or more, 6000 ppm or more, 7000 ppm or more, 8000 ppm or more, 9000 ppm or more, 10000 ppm or more, 11000 ppm or more, 12000 ppm or more, 13000 ppm or more, 14000 ppm or more, or 15000 ppm or more. The upper limit of the above lithium content (Y) is not specifically limited, but considering the degree to which lithium conduction occurs at an appropriate rate at the interface between the positive active material and the solid electrolyte particles included in the positive active material layer, it may be 25,000 ppm or less, and specifically, it may be 25,000 ppm or less, 24,000 ppm or less, 23,000 ppm or less, 22,000 ppm or less, 21,000 ppm or less, 20,000 ppm or less, 19,000 ppm or less, 18,000 ppm or less, 17,000 ppm or less, or 16,000 ppm or less.

[0072]

[0073] In one embodiment of the present invention, the core particle may be in the form of a multi-particle structure formed by the aggregation of a plurality of single particles of the positive electrode active material. When the positive electrode active material is in the form of a multi-particle structure, lithium migration at the interface can be more efficient because the specific surface area relative to the same particle size is larger compared to when it is in the form of a single particle.

[0074] In one embodiment, the positive electrode active material may include a lithium composite metal oxide capable of reversible intercalation and deintercalation of lithium.

[0075] The above lithium composite metal oxide may include, together with lithium, nickel, cobalt, and a metal element M (wherein M is at least one selected from the group consisting of Mn, Al, W, Cu, Fe, V, Cr, Ti, Zr, Zn, In, Ta, Y, La, Sr, Ga, Sc, Gd, Sm, Ca, Ce, Nb, Mg, B, and Mo).

[0076] Specifically, the lithium composite metal oxide may be represented by the following chemical formula 3:

[0077] <Chemical Formula 3>

[0078] Li α Ni x Co y M z O2

[0079] In the above chemical formula 3,

[0080] The above M is at least one selected from the group consisting of Mn, Al, W, Cu, Fe, V, Cr, Ti, Zr, Zn, In, Ta, Y, La, Sr, Ga, Sc, Gd, Sm, Ca, Ce, Nb, Mg, B, and Mo, and

[0081] The above α, x, y, and z are each the atomic fractions of independent elements, where 0.9 ≤ α ≤ 1.05, 0 <x<1, 0<y<1, 0<z<1, x+y+z=1일 수 있으며, 보다 구체적으로는 0.9≤α≤1.05, 0.6≤x<1, 0<y≤0.4, 0<z≤0.4, x+y+z=1이다. 이때 상기 α는 미충전시 값이다.

[0082] More specifically, the core particles are LiNi 0.6 Co 0.2 Mn 0.2 O2, LiNi 0.8 Mn 0.1 Co0.1 O2, LiNi 0.6 Co 0.2 Mn 0.2 W 0.02 O2 or LiNi 0.85 Co 0.09 Mn 0.045 Al 0.015 It may be a lithium complex metal oxide containing a high amount of nickel, such as O2, and at least one of these may be used.

[0083] In one embodiment, the core particles may be included in an amount of 97 to 99.9 weight% based on the total weight of the positive electrode active material. If the content of the core particles is less than 97 weight%, battery performance may be degraded, and if it exceeds 99.9 weight%, the content of the coating layer may be relatively reduced, causing adverse reactions with the solid electrolyte. Specifically, the content of the core particles may be 97 weight% or more, 97.5 weight% or more, 98 weight% or more, 98.5 weight% or more, or 99 weight% or more, and may be 99.9 weight% or less, 99.8 weight% or less, 99.7 weight% or less, 99.6 weight% or less, or 99.5 weight% or less.

[0084]

[0085] In one embodiment of the present invention, the plurality of single particles may be aggregated with orientation.

[0086] The above orientation may refer to a form arranged in a certain direction. For example, the plurality of single particles may be aggregated in a radial orientation, a vertical orientation, or a horizontal orientation, but are not limited thereto as long as the plurality of single particles have a form arranged in a certain direction.

[0087] Compared to multiply particles formed by the random aggregation of the above single particles, multiply particles formed by aggregation with orientation can exhibit the effect of facilitating the movement of lithium within the positive electrode active material.

[0088] The orientation of the core particles can be induced by adding a doping element during synthesis. That is, orientation can be induced when an appropriate amount of a doping element is added to the anode active material constituting the core particles during synthesis. The doping element may include one or more selected from the group consisting of B, Ta, and W. The doping element may be included in an amount sufficient to induce the orientation of the core particles. For example, the doping element may be included in an amount of 0.01 to 3 weight% based on the total weight of the core particles. Specifically, the content of the doping element may be 0.01 weight% or more, 0.1 weight% or more, 0.2 weight% or more, 0.3 weight% or more, 0.4 weight% or more, 0.5 weight% or more, or 1 weight% or more, and may be 3 weight% or less, 2.5 weight% or less, 2.0 weight% or less, or 1.5 weight% or less.

[0089]

[0090] In one embodiment of the present invention, the single particle may be in the form of a rod. However, the shape of the single particle is not particularly limited as long as it is a shape in which the single particles can aggregate to form multiple particles.

[0091] The aspect ratio of the cross-section of the above-mentioned single particle, that is, the ratio of the minor axis to the major axis, may be 0.5:1 or less. The longer the major axis of the above-mentioned single particle is compared to the minor axis, the more advantageous it may be for forming orientation. For example, the ratio of the minor axis to the major axis may be 0.5:1 or less, 0.4:1 or less, 0.3:1 or less, 0.2:1 or less, or 0.1:1 or less. Additionally, the ratio of the minor axis to the major axis may be 0.05:1 or more.

[0092]

[0093] In one embodiment of the present invention, the particle size (D50) of the positive active material may be 3.3 μm to 6.3 μm.

[0094] If the particle size (D50) of the above positive active material is less than 3.3 μm, the positive active materials may aggregate or the electrode plate density may decrease during positive manufacturing, and if it exceeds 6.3 μm, the lithium mobility may decrease. Specifically, the particle size (D50) of the positive electrode active material may be 3.3 μm or more, 3.4 μm or more, 3.5 μm or more, 3.6 μm or more, 3.7 μm or more, 3.8 μm or more, 3.9 μm or more, or 4 μm or more, and may be 6.3 μm or less, 6.2 μm or less, 6.1 μm or less, 6 μm or less, 5.9 μm or less, 5.8 μm or less, 5.7 μm or less, 5.6 μm or less, 5.5 μm or less, 5.4 μm or less, 5.3 μm or less, 5.2 μm or less, 5.1 μm or less, or 5 μm or less.

[0095] The particle size (D50) of the positive active material can be defined as the particle size at the 50% reference of the particle size distribution. The particle size (D50) of the positive active material particle can be measured, for example, using a laser diffraction method. More specifically, after dispersing the positive active material particle in a dispersion medium, it can be introduced into a commercially available laser diffraction particle size measuring device (e.g., Microtrac MT 3000) and irradiated with ultrasound of approximately 28 kHz at an output of 60 W, and the particle size (D50) at the 50% reference of the particle size distribution in the measuring device can be calculated.

[0096]

[0097] In one embodiment of the present invention, the thickness of the coating layer may be 1 nm to 50 nm. If the thickness of the coating layer is less than 1 nm, the effect of preventing side reactions between the core particle containing the anode active material and the solid electrolyte particle may be reduced, and if it exceeds 50 nm, the coating layer thickness may be excessively thick and act as a resistance. Specifically, the thickness of the coating layer may be 1 nm or more, 5 nm or more, 10 nm or more, 15 nm or more, 20 nm or more, or 25 nm or more, and may be 50 nm or less, 45 nm or less, 40 nm or less, 35 nm or less, or 30 nm or less.

[0098]

[0099] In one embodiment of the present invention, the coating layer may be included in an amount of 0.1 to 3 weight% based on the total weight of the positive electrode active material. If the content of the coating layer is less than 0.1 weight%, side reactions may occur between the positive electrode active material and solid electrolyte particles, and if it exceeds 3 weight%, the content of the coating layer is excessive and may act as a resistance. Specifically, the content of the coating layer may be 0.1 weight% or more, 0.2 weight% or more, 0.3 weight% or more, 0.4 weight% or more, or 0.5 weight% or more, and may be 3 weight% or less, 2.5 weight% or less, 2 weight% or less, 1.5 weight% or less, or 1 weight% or less.

[0100]

[0101] FIG. 1 is a schematic diagram of a positive electrode active material for an all-solid-state battery according to one embodiment of the present invention.

[0102] Referring to FIG. 1, a coating layer (12) is formed on the surface of a core particle (11) in a positive electrode active material (10).

[0103] The core particles (11) can be formed by aggregating single particles (P1) of the positive active material with orientation to form a multi-particle shape. For example, the single particles (P1) can be rod-shaped and can aggregate with radial orientation to form a multi-particle shape.

[0104] Additionally, the coating layer (12) may contain an oxalate-based solid electrolyte, so that the surface of the core particle (11) containing the anode active material is coated with the oxalate-based solid electrolyte.

[0105] Additionally, when the lithium metal oxide (12a) is included in the coating layer (12), the lithium metal oxide (12a) may be included adjacent to the core particle (11). The lithium metal oxide (12a) may be included in a form that coats the entire surface of the core particle (11), or it may be included in a form that is adjacent to a part of the surface of the core particle (11).

[0106]

[0107] Method for manufacturing a positive electrode active material for an all-solid-state battery

[0108] The present invention also relates to a method for manufacturing a positive electrode active material for an all-solid-state battery. The types, physical properties, and content of the core particles, oxosulfide-based solid electrolyte, and lithium metal oxide material used in manufacturing the positive electrode active material for the all-solid-state battery are as described above. The orientation of the core particles can be induced by adding a doping element during the synthesis of the positive electrode active material contained in the core particles. That is, orientation can be induced when an appropriate amount of a doping element is added to the positive electrode active material constituting the core particles during synthesis. The doping element may include one or more selected from the group consisting of B, Ta, and W.

[0109]

[0110] A method for manufacturing a positive electrode active material for an all-solid-state battery according to one embodiment of the present invention may include the step of coating a core particle surface with an oxalate-based solid electrolyte. The manufactured positive electrode active material comprises a core particle and a coating layer, wherein the coating layer comprises an oxalate-based solid electrolyte.

[0111] In one embodiment of the present invention, the coating layer comprising the oxalate-based solid electrolyte may be formed by a dry coating method. Additionally, a heat treatment may be performed after carrying out the dry coating method.

[0112] The above dry coating method is not particularly limited as long as it is a coating method that does not use a solvent. For example, the dry coating method may involve coating the surface of the core particles with the oxosulfide-based solid electrolyte using mechanical force. The above dry coating method may be performed by mechanical milling. The above mechanical milling is not particularly limited as long as it is a milling method commonly used in the art, and may be, for example, ball milling, mechanofusion milling, shaker milling, planetary milling, attritor milling, or disk milling.

[0113] In addition, after the above dry coating, a heat treatment may be additionally performed to sinter. Through the above heat treatment, the coating layer containing the oxalate-sulfide solid electrolyte can be maintained more firmly. The heat treatment temperature can be appropriately selected within a temperature range that allows the coating layer to be coated and maintained more firmly without the anode active material contained in the core particles and the oxalate-sulfide solid electrolyte contained in the coating layer being degraded. For example, the heat treatment temperature may be 100°C to 300°C. If the heat treatment temperature is below 100°C, the bonding force between the core particles and the coating layer may not be sufficient, and if it exceeds 300°C, the oxalate-sulfide solid electrolyte component contained in the coating layer may diffuse into the core particles. Specifically, the heat treatment temperature may be 100°C or higher, 110°C or higher, 120°C or higher, 130°C or higher, 140°C or higher, 150°C or higher, 160°C or higher, 170°C or higher, 180°C or higher, or 190°C or higher, and may be 300°C or lower, 290°C or lower, 280°C or lower, 270°C or lower, 260°C or lower, 250°C or lower, 240°C or lower, 230°C or lower, 220°C or lower, or 210°C or lower.

[0114]

[0115] A method for manufacturing a positive electrode active material for an all-solid-state battery according to another embodiment of the present invention comprises: (S1) mixing a lithium metal oxide with an alcohol-based solvent to form a first mixed solution for forming a coating layer; (S2) mixing a core particle into the first mixed solution to form a second mixed solution for forming a positive electrode active material; (S3) filtering and pressing the second mixed solution; (S4) calcining the product obtained in step (S3) to form a coating layer containing a lithium metal oxide on the surface of the core particle; and (S5) mixing an oxalide-based solid electrolyte with the product obtained in step (S4) and calcining to form a coating layer containing an oxalide-based solid electrolyte.

[0116]

[0117] In one embodiment of the present invention, in step (S1), a lithium metal oxide can be mixed with an alcohol-based solvent to form a first mixed solution for forming a coating layer.

[0118] The raw material for synthesizing the above lithium metal oxide may be mixed in an alcohol-based solvent, and the lithium metal oxide itself may be mixed in an alcohol-based solvent.

[0119] The above alcohol-based solvent may comprise one or more alcohol compounds having 1 to 4 carbon atoms. Specifically, the above alcohol-based solvent may comprise one or more selected from the group consisting of acetone, methanol, ethanol, isopropyl alcohol, butyl alcohol, octyl alcohol, and allyl alcohol. Considering processability in the cathode active material manufacturing process, the above alcohol-based solvent may be ethanol.

[0120]

[0121] In one embodiment of the present invention, in step (S2), a core particle may be mixed into the first mixed solution to form a second mixed solution for forming an anode active material.

[0122] The concentration of the second mixed solution may be 30 to 70 weight% based on the solid content. In this case, the solid content refers to the weight of the lithium metal oxide and core particles excluding the solvent. The solid content may be appropriately adjusted considering the extent to which a coating layer containing the lithium metal oxide can be formed. For example, the solid content may be 30 weight% or more, 35 weight% or more, 40 weight% or more, or 45 weight% or more, and may be 70 weight% or less, 65 weight% or less, 60 weight% or less, or 55 weight%.

[0123] In addition, the weight ratio of the lithium metal oxide to the core particles may be 0.1 to 1:99 to 99.9, 0.2 to 0.8:99.2 to 99.8, or 0.3 to 0.7:99.3 to 99.7.

[0124]

[0125] In one embodiment of the present invention, in step (S3), the second mixed solution may be filtered and pressed.

[0126] The above filtration pressing may be a process of removing the alcohol-based solvent by pressurizing the second mixed solution for forming the anode active material to 0.3 to 1 MPa. For example, the pressurization may be performed by air blowing, and the alcohol-based solvent may be removed by pressurizing with air blowing for 5 to 15 minutes. Additionally, the filtration pressing may remove the alcohol-based solvent from the second mixed solution containing the coating raw material and core particles using a press-type filtration device. The press-type filtration device is not particularly limited as long as it is a device generally used in the relevant technical field and capable of effectively removing the alcohol-based solvent.

[0127] By the above filtration and pressing, the alcohol-based solvent can be removed from the second mixed solution in a short time, thereby minimizing the time the core particles are exposed to the liquid.

[0128] The filtered pressed material obtained after the above filtration and pressing is in a form in which lithium metal oxide is adsorbed on the surface of the core particles, and a trace amount of alcohol-based solvent may be present in the filtered pressed material. The filtered pressed material can be said to have the form of an anode active material having a coating layer formed on the surface of the core particles.

[0129]

[0130] In one embodiment of the present invention, in step (S4), the result obtained in step (S3) can be calcined to form a coating layer containing lithium metal oxide on the surface of the core particles.

[0131] The alcohol-based solvent can be completely removed by the above drying.

[0132] The above drying temperature is not particularly limited as long as it is a temperature capable of removing the alcohol-based solvent. For example, the drying may be performed at 80°C to 120°C. If the drying temperature is below 80°C, the alcohol-based solvent may not be completely removed, and if it exceeds 120°C, the physical properties of the raw material may be altered, and the performance of the manufactured cathode active material may be degraded. Specifically, the drying temperature may be 80°C or higher, 85°C or higher, or 90°C or higher, and 120°C or lower, 115°C or lower, or 110°C or lower.

[0133] The dried material obtained after the above drying is in a state where lithium metal oxide is adsorbed on the surface of the core particles.

[0134]

[0135] In one embodiment of the present invention, in step (S5), a coating layer containing an oxalate-based solid electrolyte may be formed by dry coating the result obtained in step (S4). The dry coating method is as described above.

[0136]

[0137] cathode for all-solid-state batteries

[0138] The present invention also relates to a positive electrode for an all-solid-state battery.

[0139] A positive electrode for an all-solid-state battery according to the present invention comprises 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 comprises a positive electrode active material, solid electrolyte particles, a binder, and a conductive material as described above. The solid electrolyte particles may be sulfide-based solid electrolyte particles.

[0140]

[0141] The positive active material according to one embodiment of the present invention is as described above.

[0142] In addition, the positive active material may be included in an amount of 50 to 95 weight% based on the total weight of the positive active material layer. Specifically, the content of the positive active material may be 50 weight%, 55 weight% or more, or 60 weight% or more, and may be 95 weight% or less, 90 weight% or less, 85 weight% or less, 80 weight% or less, 75 weight% or less, or 70 weight% or less. If the content of the positive active material is less than 50 weight%, the energy density may decrease, and if it exceeds 95 weight%, the mass transfer resistance may increase.

[0143]

[0144] In one embodiment of the present invention, the sulfide-based solid electrolyte is a solid electrolyte containing sulfur among solid electrolytes and can improve ion conductivity.

[0145] The above 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 above sulfide-based solid electrolyte is not limited to these, and sulfide-based solid electrolytes commonly used in the industry may be widely used.

[0146] In addition, the particle size (D50) of the sulfide-based solid electrolyte may be in the form of particles ranging from 0.1 μm to 1.5 μm. 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 1.5 μm or less, 1.2 μm or less, 1.0 μm or less, or 0.9 μm or less. If the particle size (D50) of the sulfide-based solid electrolyte is less than 0.1 μm, the ultrafine sulfide-based solid electrolyte particles may not be sufficiently dispersed within the positive active material layer and may aggregate, and if it is greater than 1.5 μm, dispersion may be somewhat easier, but the contact surface with the positive active material particles may decrease and the porosity of the positive electrode may increase.

[0147] In addition, the sulfide-based solid electrolyte may be included in an amount of 5 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 5 weight% or more, 8 weight% or more, 10 weight% or more, 13 weight% or more, 15 weight% or more, 18 weight% or more, or 20 weight% or more, and may be 50 weight% or less, 45 weight% or less, 40 weight% or less, 35 weight% or less, 30 weight% or less, or 25 weight% or less. If the content of the sulfide-based solid electrolyte is less than 10 weight%, the ionic conductivity may decrease, and if it exceeds 50 weight%, the content of the positive electrode active material and the conductive material may decrease relatively, thereby degrading battery performance.

[0148]

[0149] In one embodiment of the present invention, the binder may be included to assist in the bonding between materials included in the positive active material layer and the bonding between the positive active material layer and the positive current collector.

[0150] The above binder is 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, hydroxypropyl cellulose, 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. It may include one or more selected from the group consisting of polyacrylamide, polyurethane, polyvinylidene fluoride, and poly(vinylidene fluoride)-hexafluoropropene. Preferably, the binder may include polytetrafluoroethylene (PTFE).

[0151] In addition, the binder may be included in an amount of 0.1 to 3 weight% based on the total weight of the positive active material layer. Specifically, the content of the binder may be 0.1 weight% or more, 0.5 weight% or more, or 0.8 weight% or more, and may be 1.5 weight% or less, 2 weight% or less, or 3 weight% or less. If the content of the binder is less than 0.1 weight%, the effect of improving the binding force between materials included in the positive active material layer is negligible, so the positive active material layer may not be properly formed, and if it exceeds 3 weight%, the ionic conductivity or electrical conductivity may decrease.

[0152]

[0153] In one embodiment of the present invention, the conductive material can improve electron conductivity by forming a path capable of conducting electrons.

[0154] The above conductive material may be a linear conductive material, and the linear conductive material may be one or more selected from the group consisting of carbon nanotubes (CNT) and carbon nanofibers (CNF). The above linear conductive material may improve electrical conductivity due to its morphological characteristics. For example, the aspect ratio (length / diameter) of the above linear conductive material may be 2 or more, and specifically, the aspect ratio may be 2 or more, 5 or more, 10 or more, 20 or more, 30 or more, 40 or more, 50 or more, or 100 or more. If the aspect ratio is less than 2, it is difficult to form an electron conduction path, so the electron conductivity may decrease. In addition, although the upper limit of the above aspect ratio is not specifically limited, considering the ease of forming an electron conduction path, it may be 300 or less, 400 or less, 500 or less, 600 or less, or 700 or less.

[0155] In addition, the conductive material may be included in an amount of 1 to 10 weight percent based on the total weight of the positive electrode active material layer. Specifically, the content of the conductive material may be 1 weight percent or more, 2 weight percent or more, or 3 weight percent or more, and 6 weight percent or less, 7 weight percent or less, 8 weight percent or less, 9 weight percent or less, or 10 weight percent or less. If the content of the conductive material is less than 1 weight percent, the electrical conductivity of the positive electrode may decrease, and if it exceeds 10 weight percent, the content of the positive electrode active material and the sulfide-based solid electrolyte may decrease relatively, thereby degrading battery performance.

[0156]

[0157] In one embodiment of the present invention, the thickness of the positive 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 200 μm or less, 250 μm or less, or 300 μm or less. However, the thickness of the positive active material layer is not limited thereto.

[0158]

[0159] 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.

[0160] 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.

[0161] 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.

[0162]

[0163] All-solid-state battery

[0164] The present invention also relates to an all-solid-state battery comprising the anode.

[0165] 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.

[0166]

[0167] In one embodiment of the present invention, the cathode comprises a cathode active material layer, and the cathode active material layer may be formed on one surface of a cathode current collector. The cathode active material layer may comprise a cathode active material and a conductive material.

[0168] The above 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.

[0169] 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).

[0170] 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.

[0171] 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.

[0172]

[0173] 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).

[0174] 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.

[0175] 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.

[0176] 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.

[0177]

[0178] In one embodiment of the present invention, the sulfide-based solid electrolyte included in the sulfide-based solid electrolyte membrane 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 sulfide-based solid electrolytes commonly used in the industry may be widely used.

[0179]

[0180] battery module

[0181] 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.

[0182] Specific examples of the above-mentioned device include, but are not limited to: a power tool that moves by receiving power from an electric motor; electric vehicles including electric vehicles (EVs), hybrid electric vehicles (HEVs), and plug-in hybrid electric vehicles (PHEVs); electric two-wheeled vehicles including electric bicycles (E-bikes) and electric scooters (E-scooters); electric golf carts; and power storage systems. Preferred embodiments are presented below to aid in understanding the present invention, but the following embodiments are merely illustrative of the present invention and it is obvious to those skilled in the art that various changes and modifications are possible within the scope and spirit of the present invention, and that such changes and modifications fall within the scope of the appended claims.

[0183] 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.

[0184]

[0185] In the following examples and comparative examples, a positive electrode active material with a coating layer formed according to the requirements described in Table 1 below was prepared.

[0186]

[0187] Cathode active material core particle coating layer D50 (㎛) material particle shape particle orientation present / absent solid electrolyte lithium metal oxide Example 1 NCM811 multi-particle ○ oxosulfide-based LiNbO34 Example 2 NCM811 multi-particle X oxosulfide-based LiNbO34 Example 3 NCM811 multi-particle ○ oxosulfide-based X4 Example 4 NCM811 multi-particle X oxosulfide-based X4 Comparative Example 1 NCM811 multi-particle ○ XL LiNbO34 Comparative Example 2 NCM811 multi-particle XX LiNbO34

[0188]

[0189] Example 1

[0190] A manufacturing process was carried out as follows to produce an anode active material comprising a core particle, a first coating layer comprising a lithium metal oxide formed on the surface of the core particle, and a second coating layer comprising an oxalate-based solid electrolyte formed on the surface of the first coating layer.

[0191] NMC811 was prepared as a core particle, and synthesized NMC811 was prepared by adding B as a doping element to induce orientation.

[0192] Lithium ethoxide and niobium ethoxide were mixed in ethanol, an alcohol-based solvent, as raw materials for the first coating layer to obtain a first mixed solution for forming the first coating layer.

[0193] NCM811 doped with B, the core particle, was mixed into the first mixed solution to obtain a second mixed solution for forming an anode active material. In addition, the solid content of the second mixed solution was set to 50 wt%, wherein the solid content refers to the weight of the raw material of the coating layer and the core particle, excluding the alcohol-based solvent. Furthermore, the weight ratio of the raw material of the first coating layer and the core particle was set to 0.5:99.5.

[0194] The above second mixed solution was filtered and pressed to remove the alcohol-based solvent.

[0195] Subsequently, a positive electrode active material precursor was obtained in the form of a first coating layer containing a lithium metal oxide formed on the surface of the core particle. At this time, the lithium metal oxide included in the first coating layer is LiNbO3.

[0196] The above positive active material precursor was dried in a vacuum oven at 100°C for 12 hours to completely remove the alcohol-based solvent. Afterwards, the dried positive active material precursor was calcined and milled at 400°C for 9 hours.

[0197] Subsequently, an oxysulfide-based solid electrolyte was mixed with the above-mentioned positive active material precursor, and a second coating layer containing the oxysulfide-based solid electrolyte was formed by coating the surface of the first coating layer with the oxysulfide-based solid electrolyte through mechanical milling to produce a positive active material. The oxysulfide-based solid electrolyte was Li6PS 4.5 O 0.5 Cl was used.

[0198] As a result of measurement using a particle size analyzer (Mastersizer 3000+ pro), it was confirmed that the particle size (D50) of the manufactured cathode active material was 4 μm. In addition, regarding the cross-section of the manufactured cathode active material captured by a scanning electron microscope (SEM), it was confirmed using an image analysis program (Image J, NIH) that the core particles contained in the cathode active material were in a multi-particle form and oriented radially.

[0199]

[0200] Example 2

[0201] A positive electrode active material was prepared in the same manner as in Example 1, except that the NCM811 contained in the core particles was not oriented. In this case, the NCM811 was synthesized without adding the doping element B.

[0202]

[0203] Example 3

[0204] A positive electrode active material was prepared in the same manner as in Example 1, except that a first coating layer containing lithium metal oxide was not formed.

[0205]

[0206] Example 4

[0207] A positive electrode active material was prepared in the same manner as in Example 2, except that a first coating layer containing lithium metal oxide was not formed.

[0208]

[0209] Comparative Example 1

[0210] A positive electrode active material was prepared in the same manner as in Example 1, except that a second coating layer containing an oxalate-based solid electrolyte was not formed.

[0211]

[0212] Comparative Example 2

[0213] A positive electrode active material was prepared in the same manner as in Example 2, except that a second coating layer containing an oxalate-based solid electrolyte was not formed.

[0214]

[0215] Experimental Example 1: Coating Layer Analysis

[0216] As a result of confirmation using SEM EDS (JEOL, JSM-IT800), it was confirmed that O, S, P, and Nb were present in the coating layer of Example 1.

[0217] In addition, X-ray Photoelectron Spectroscopy (XPS) analysis confirmed the presence of oxalate-based solid electrolytes and LiNbO3 on the surface of the core particles.

[0218]

[0219] Experimental Example 2: Performance Evaluation

[0220] To evaluate the performance of all-solid-state batteries using the positive active materials prepared in the examples and comparative examples, charge-discharge experiments were conducted in pressed cells. In the case of a pressed cell, the positive electrode, electrolyte, and negative electrode are stacked within the corresponding mold. For the cell fabrication method, a positive electrode composite was prepared by mixing the positive active material, Super-P (manufacturer: Imerys) as a conductive material, and a Li2S-P2S5 sulfide-based electrolyte in a weight ratio of 70:25:5. Li-In was used as the counter electrode (negative electrode). The all-solid-state battery cell was manufactured as follows: A solid electrolyte was placed into the corresponding mold and pressed to form a solid electrolyte layer. Subsequently, the positive active material composite was applied to one side of the solid electrolyte layer, and a negative electrode was stacked on the other side. After additional pressing, an electrode assembly was manufactured. The manufactured electrode assembly was placed inside a battery case to produce an all-solid-state battery. The capacity capability of the above-described all-solid-state battery was observed through a protocol in which the battery was activated at 0.1C for 2 cycles in a charger / discharger and then discharged up to 1C. Specifically, the capacity capability was observed through a protocol in which 0.1C CC / CV (Constant Current / Constant Voltage) charging and 0.05C CC (Constant Current) discharge cycles were performed in the charger / discharger, followed by maintaining the 0.1C CC / CV charging process while discharging in CC at 0.1C / 0.2C / 0.33C / 0.5C / 1C.

[0221]

[0222] Table 2 below lists the results of the above experiment.

[0223]

[0224] 0.1C FM1C Charge (mAh / g) Discharge (mAh / g) Efficiency (%) Retention (%) Example 1 2 2 8 2 10 9 2 9 7 Example 2 2 2 7 2 11 9 3 9 4 Example 3 2 2 9 20 8 9 1 9 5 Example 4 2 3 12 9 9 0 9 5 Comparative Example 1 2 3 0 20 8 9 0 9 3 Comparative Example 2 2 3 12 6 8 9 9 0

[0225]

[0226] Referring to Table 2 above, it can be seen that Comparative Examples 1 and 2 are positive active materials without a coating layer containing an oxide-based solid electrolyte, and their capacity retention rate is relatively poor compared to Examples 1 to 4.

[0227] In addition, Examples 1 and 2 are positive electrode active materials in which both a first coating layer containing lithium metal oxide and a second coating layer containing an oxide-based solid electrolyte are formed on the core particles, and it can be seen that the overall performance is somewhat higher or similar compared to Examples 3 and 4 in which only the second coating layer is formed.

[0228] In addition, it can be seen that when the core particles have orientation, as in Examples 1 and 3, the overall performance is relatively higher or similar compared to Examples 2 and 4, which do not have orientation.

[0229]

[0230] [Explanation of the symbol]

[0231] 10: Positive electrode active material

[0232] 11: Core Particle

[0233] 12: Coating layer

[0234] 12a: Lithium metal oxide

[0235] P1: Single particle

Claims

1. A positive electrode active material for an all-solid-state battery comprising a core particle; and a coating layer located on the surface of the core particle, wherein A positive electrode active material for an all-solid-state battery, wherein the above coating layer comprises an oxysulfide-based solid electrolyte.

2. In Paragraph 1, The above oxosulfide-based solid electrolyte is a positive electrode active material for an all-solid-state battery, comprising oxygen (O) and sulfur (S) in a weight ratio of 0.02:1 to 0.1:

1.

3. In Paragraph 1, A positive electrode active material for an all-solid-state battery, wherein the above oxysulfide-based solid electrolyte is represented by the following chemical formula 1: <Chemical Formula 1> Li (7-x) P.S. (6-x-y) About y Yes x In the above chemical formula 1, Ha is Cl, Br, or I, 0 < x < 1.6, and 0.1 < y < 1.

4. In Paragraph 1, The above oxalide-based solid electrolyte is a positive electrode active material for an all-solid-state battery having an azirodite-type crystal structure.

5. In Paragraph 1, A positive electrode active material for an all-solid-state battery, wherein the above oxosulfide-based solid electrolyte is included in an amount of 0.1% to 2% by weight based on the total weight of the positive electrode active material.

6. In Paragraph 1, A positive electrode active material for an all-solid-state battery, wherein the coating layer further comprises a lithium metal oxide.

7. In Paragraph 6, A positive electrode active material for an all-solid-state battery, wherein the coating layer comprises a first coating layer comprising a lithium metal oxide and a second coating layer comprising an oxide-sulfide-based solid electrolyte.

8. In Paragraph 1, The above-mentioned core particle is a multi-particle form formed by the aggregation of multiple single particles of the positive active material, a positive active material for an all-solid-state battery.

9. In Paragraph 8, A positive electrode active material for an all-solid-state battery, wherein the above plurality of single particles are aggregated with orientation.

10. In Paragraph 8, A positive electrode active material for an all-solid-state battery, wherein the aspect ratio of the above single particles is 0.05:1 to 0.5:

1.

11. In Paragraph 1, A positive electrode active material for an all-solid-state battery, wherein the particle size (D50) of the positive electrode active material is 3.3 μm to 6.3 μm.

12. A positive electrode for an all-solid-state battery comprising a positive electrode active material, a solid electrolyte particle, a binder, and a conductive material according to any one of claims 1 to 11.

13. An all-solid-state battery comprising the positive electrode of paragraph 12.

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