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

Abstract

The present invention relates to a cathode for an all-solid-state battery, and an all-solid-state battery including the same, the cathode including: a current collector; and a cathode active material layer disposed on the current collector, wherein the cathode active material layer includes a cathode active material, a binder, and a solid electrolyte represented by Formula 1: and the cathode active material has an effect of reducing the porosity of the cathode and improving ion conductivity and electrical conductivity.[Formula 1] Li a P b S c Cl d X e In Formula 1, 4 ≤ a ≤ 7, 0 ≤ b ≤ 1, 3 ≤ c ≤ 5, 0 ≤ d < 0.3, and d

Description

Technical Field

[0001] This application claims the benefit of priority based on Korean Patent Application No. 10-2024-0099100, filed on July 26, 2024, the disclosure of which is incorporated herein by reference in its entirety.

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

[0003] Lithium-ion batteries are widely used as power sources for portable devices, including IT mobile devices, and the market has recently expanded from small lithium-ion batteries to medium and large-sized batteries. In particular, the use of batteries in automobiles is rapidly increasing. As a power source for electric vehicles, lithium-ion batteries require high energy density and high power characteristics, and ensuring safety is considered paramount.

[0004] Conventional lithium-ion batteries use liquid non-aqueous organic electrolytes, which pose a risk of ignition and explosion. Given the ongoing explosions of products using this technology, addressing this issue is urgently needed.

[0005] All-solid-state batteries are batteries that replace liquid organic electrolytes with solid electrolytes. All components of the battery, including the electrodes and electrolyte, are solid. Due to the high safety of the solid electrolyte, the risk of ignition or explosion can be fundamentally eliminated.

[0006] Solid electrolytes for all-solid-state lithium secondary batteries can be gel-type polymer electrolytes, sulfide-based solid electrolytes, or oxide-based solid electrolytes. Among these, sulfide-based solid electrolytes have a strength greater than 1 × 10⁻⁶. -2 The high lithium-ion conductivity (S / cm) and wide potential window (greater than 5V) result in less performance degradation even under extreme conditions, and offer significant advantages when designing high-energy-density lithium-ion rechargeable batteries.

[0007] Because all-solid-state batteries use solid electrolytes, the positive electrode active material layer must include a solid electrolyte for lithium-ion conduction pathways. Therefore, the positive electrode active material layer in an all-solid-state battery must comprise a positive electrode active material, a binder, and a solid electrolyte. To reduce the porosity of the positive electrode in all-solid-state batteries, improve ion conductivity and electrical conductivity, and increase the energy density of the all-solid-state battery, it is necessary to improve the structure of the solid electrolyte contained in the positive electrode active material layer; therefore, research in these areas is required.

[0008] [Existing technical documents]

[0009] [Patent Literature]

[0010] (Patent Document 1) Korean Patent Publication No. 10-2228383 Summary of Invention

[0011] [Technical Problem]

[0012] An object of the present invention is to provide a positive electrode for an all-solid-state battery, which can reduce the porosity of the positive electrode and improve ionic conductivity and electrical conductivity.

[0013] An object of the present invention is to provide an all-solid-state battery which has excellent energy density by including the above positive electrode.

[0014] [Technical Solution]

[0015] In view of the above technical objects, the present invention provides a positive electrode for an all-solid-state battery, comprising: a current collector; and a positive electrode active material layer disposed on the current collector, wherein the positive electrode active material layer comprises a positive electrode active material, a binder, and a solid electrolyte represented by Formula 1: [Formula 1] Li a P b S c Cl d X e wherein 4≤a≤7, 0≤b≤1, 3≤z≤5, 0≤d<0.3, d<e≤3, and X is Br or I.

[0016] Further, the present invention provides an all-solid-state battery comprising: the above positive electrode of the present invention; a negative electrode; and a solid electrolyte layer disposed between the positive electrode and the negative electrode.

[0017] [Advantageous Effects]

[0018] The positive electrode for an all-solid-state battery according to the present invention includes a solid electrolyte containing an excess amount of bromine or iodine, thereby reducing the porosity of the positive electrode and improving the ionic conductivity and electrical conductivity of the positive electrode.

[0019] Further, the all-solid-state battery including the positive electrode of the present invention can exhibit excellent energy density. Brief Description of Drawings

[0020] Figure 1 is the measurement result of the porosity of the positive electrode of Experimental Example 1.

[0021] Figure 2 is the measurement result of the discharge capacity of the positive electrode of Experimental Example 3.

[0022] Figure 3 is the measurement result of the life cycle characteristics of the positive electrode of Experimental Example 3. Detailed Description of Embodiments

[0023] Terms and words used in the description and claims shall not be interpreted merely in their typical or dictionary meaning, but shall be interpreted in accordance with the principle that an inventor can appropriately define the concept of terms to best explain his or her own invention, in a meaning and concept consistent with the technical idea of the present invention.

[0024] The terms used in the present invention are only for the purpose of describing specific embodiments, and are not intended to limit the present invention. Unless the context clearly indicates otherwise, singular expressions shall include plural expressions. As used in the present invention, terms such as "comprising" or "having" are intended to specify the presence of the stated features, integers, steps, operations, components, parts or combinations thereof, but do not exclude the possibility of the presence or addition of one or more other features, integers, steps, operations, components, parts or combinations thereof.

[0025] Hereinafter, the present invention will be described in more detail.

[0026] All-solid-state batteries use a solid electrolyte instead of a liquid electrolyte, and the positive electrode active material layer contains the solid electrolyte to ensure a conduction path for lithium ions. In the present invention, by improving the solid electrolyte contained in the positive electrode active material layer, it is intended to provide a positive electrode for an all-solid-state battery with low porosity and improved ionic conductivity and electrical conductivity.

[0027] Positive electrode for all-solid-state batteries

[0028] The present invention relates to a positive electrode for an all-solid-state battery, comprising: a current collector; and a positive electrode active material layer disposed on the current collector, wherein the positive electrode active material layer comprises a positive electrode active material, a binder, and a solid electrolyte represented by Formula 1: [Formula 1] Li a P b S c Cl d X e wherein 4≤a≤7, 0≤b≤1, 3≤z≤5, 0≤d<0.3, d<e≤3, and X is Br or I.

[0029] Accordingly, the solid electrolyte of Formula 1 may be Li a P b S c Cl d Br e or Li a P b S c Cl d I e .

[0030] In Formula 1, 0≤d<0.3, preferably 0<d<0.3.

[0031] In addition, in Formula 1, d < e ≤ 3, and e may satisfy e ≥ 7d. When e ≥ 7d, d is not zero. Since in Formula 1, d < e ≤ 3 and e ≥ 7d, X can be contained in an excessive amount in Formula 1. When X is contained in an excessive amount in Formula 1, the contact area between the solid electrolyte of Formula 1 and the positive electrode active material can be increased, thereby improving the ionic conductivity and electrical conductivity of the positive electrode. Therefore, an all-solid-state battery including the positive electrode can achieve increased energy density.

[0032] Thereby, low porosity of the positive electrode for an all-solid-state battery can be ensured, and ionic conductivity and electrical conductivity can be improved. If e ≤ d or e < 7d, X is not contained in an excessive amount, and thus the above effect cannot be obtained. In addition, it is preferred that e satisfies 0.5 ≤ e ≤ 3, and most preferably, e satisfies 0.5 ≤ e ≤ 1.5.

[0033] Based on the total weight of the positive electrode active material layer, the content of the solid electrolyte of Formula 1 is 3 wt% to 30 wt%. Specifically, the content of the solid electrolyte of Formula 1 may be 3 wt% or more, 5 wt% or more, 7 wt% or more, or 10 wt% or more, and may be 30 wt% or less, 25 wt% or less, 20 wt% or less, or 10 wt% or less. If the content of the solid electrolyte of Formula 1 is less than 3 wt%, the effect of improving the ionic conductivity and electrical conductivity of the positive electrode may not be significant. If it exceeds 30 wt%, the contents of the positive electrode active material and the binder are relatively reduced, thereby deteriorating the performance of the battery.

[0034] The positive electrode active material may vary depending on the type of the all-solid-state battery. For example, the positive electrode active material may include: layered compounds such as lithium cobalt oxide (LiCoO2), lithium nickel oxide (LiNiO2), or compounds substituted with one or more transition metals; lithium manganese oxides such as Li 1+x Mn 2-x O4 (0 ≤ x ≤ 0.33), LiMnO3, LiMn2O3 or LiMnO2; lithium copper oxide (Li2CuO2); vanadium oxides such as LiV3O8, V2O5 or Cu2V2O7; lithium nickel oxide at Ni site represented by formula LiNi 1-x M x O2 (M = Co, Mn, Al, Cu, Fe, Mg, B or Ga; 0.01 ≤ x ≤ 0.3); lithium manganese composite oxide represented by LiMn 2-x M x O2 (M = Co, Ni, Fe, Cr, Zn or Ta; 0.01 ≤ x ≤ 0.1) or Li2Mn3MO8 (M = Fe, Co, Ni, Cu or Zn); represented by LiNi x Mn 2-xO4 represents spinel-structured lithium manganese composite oxides; LiCoPO4; LiFePO4; elemental sulfur (S8); sulfur-based compounds such as Li2S n (n≥1), organic sulfur compounds or carbon-sulfur polymers (C2S) x ) n (x = 2.5 to 50, n = 2), but not limited to these.

[0035] Based on the total weight of the positive electrode active material layer, the content of the positive electrode active material can range from 65% to 95% by weight. Specifically, the content of the positive electrode active material can be above 65% by weight, above 70% by weight, above 75% by weight, or above 80% by weight. It can also be below 95% by weight, below 90% by weight, or below 85% by weight. If the content of the positive electrode active material is less than 65% by weight, the battery performance may decrease, and if it exceeds 95% by weight, the mass transfer resistance may increase.

[0036] Adhesives are used to improve the adhesion between the components constituting the positive electrode active material layer, and the adhesion between these components and the current collector. Any adhesive known in the art can be used.

[0037] For example, the adhesive can be: fluoropolymer adhesives, including polyvinylidene fluoride (PVdF) or polytetrafluoroethylene (PTFE); rubber adhesives, including styrene-butadiene rubber (SBR), acrylonitrile-butadiene rubber, or styrene-isoprene rubber; cellulose adhesives, including carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, or regenerated cellulose; polyol adhesives; polyolefin adhesives, including polyethylene or polypropylene; polyimide adhesives; polyester adhesives; and silane adhesives. Mixtures or copolymers of one or more of these groups can be used.

[0038] Furthermore, based on the total weight of the positive electrode active material layer, the binder content can range from 0.1 wt% to 5 wt%. Specifically, the binder content can be 0.1 wt% or more, 0.5 wt% or more, or 0.8 wt% or more, and can be 5 wt% or less, 4 wt% or less, 3 wt% or less, 2 wt% or less, or 1.5 wt% or less. If the binder content is less than 0.1 wt%, the enhancement of adhesion between the materials contained in the positive electrode active material layer may not be significant, which may lead to poor electrode sheet formation. If it exceeds 5 wt%, the ionic conductivity or electrical conductivity of the positive electrode may deteriorate.

[0039] The positive electrode active material layer may further contain conductive materials. There are no particular restrictions on the conductive materials, as long as they have excellent conductivity and do not cause side reactions or chemical changes in the internal environment of the all-solid-state battery.

[0040] For example, conductive materials can be: graphite or conductive carbon, such as natural or artificial graphite; carbon black, such as acetylene black, Ketjen black, Denka black, thermally cracked carbon black, channel black, furnace black, or lamp black; carbonaceous materials having a graphene or graphite crystal structure; conductive fibers, such as carbon fibers or metal fibers; fluorinated carbon; metal powders, such as aluminum powder or nickel powder; conductive whiskers, such as zinc oxide whiskers or potassium titanate whiskers; conductive metal oxides, such as titanium oxide; and conductive polymers, such as polyphenylene derivatives. These can be used alone or in combination of two or more, but are not limited thereto. Preferably, the conductive material can include vapor-grown carbon fibers (VGCF).

[0041] Based on the total weight of the positive electrode active material layer, the content of conductive material can be greater than 0 wt% and less than or equal to 5 wt%. Specifically, the content of conductive material can be greater than 0.1 wt%, greater than 0.5 wt%, greater than 1 wt%, greater than 1.5 wt%, or greater than 2 wt%, and can be less than 5 wt%, less than 4 wt%, or less than 3 wt%. Without conductive material, it may be difficult to expect improved conductivity, or the electrochemical characteristics of the battery may deteriorate. If the content exceeds 5 wt%, the amount of positive electrode active material may become relatively small, thereby reducing capacity and energy density.

[0042] In one embodiment of the present invention, the positive electrode active material layer can be formed by coating a positive electrode active material layer forming composition comprising a positive electrode active material, a solid electrolyte of Formula 1, and a binder onto a current collector, wherein the composition may be solvent-free. Therefore, the positive electrode for all-solid-state batteries of the present invention can be a dry positive electrode.

[0043] In another embodiment of the present invention, the positive electrode active material layer can be formed by coating a positive electrode active material layer forming composition comprising a positive electrode active material, a solid electrolyte of Formula 1, a binder, and a solvent onto a current collector and then drying it. Therefore, the positive electrode for all-solid-state batteries of the present invention can be a wet positive electrode.

[0044] The positive electrode current collector serves as a support for the positive electrode active material layer and is not particularly limited, as long as it has good conductivity and is electrochemically stable within the voltage range of the lithium secondary battery. For example, the positive electrode current collector can be any metal selected from the group consisting of copper, aluminum, stainless steel, titanium, silver, palladium, nickel, their alloys, and combinations thereof, wherein stainless steel can be surface-treated with carbon, nickel, titanium, or silver, and the alloy can preferably be an aluminum-cadmium alloy, but can also be a non-conductive polymer surface-treated with calcined carbon or conductive materials or conductive polymers.

[0045] The positive electrode current collector can form microscopic bumps and depressions on its surface to enhance the adhesion to the positive electrode active material. It can be used in various forms, such as film, sheet, foil, mesh, net, porous body, foam, non-woven body, etc.

[0046] The porosity of the positive electrode can be from 0.1% to 40%. As described above, since the positive electrode active material layer contains the solid electrolyte of Formula 1, the contact area between the positive electrode active material and the solid electrolyte of Formula 1 can be increased, thereby obtaining the porosity within the above range. Therefore, the positive electrode of the present invention can have an effectively formed ion conduction path.

[0047] Furthermore, the ionic conductivity of the positive electrode at 60℃ can be 1 × 10⁻⁶. -6 mS / cm up to 1 × 10 -3 mS / cm, and the conductivity can be 1 × 10⁻⁶ mS / cm. -6 mS / cm up to 1 × 10 -3 mS / cm. As described above, since the positive electrode active material layer contains the solid electrolyte of Formula 1, the contact area between the positive electrode active material and the solid electrolyte can be increased. Therefore, as described above, the positive electrode of the present invention can have excellent ionic conductivity and electrical conductivity.

[0048] All-solid-state batteries

[0049] The present invention relates to an all-solid-state battery, comprising a positive electrode, a negative electrode, and a solid electrolyte layer between the positive electrode and the negative electrode, wherein the positive electrode is the positive electrode of the present invention as described above.

[0050] The negative electrode may include a negative electrode current collector and a layer of negative electrode active material on the negative electrode current collector. Furthermore, like the positive electrode, the negative electrode may include conductive material and a binder as needed. The negative electrode current collector, conductive material, and binder are described above.

[0051] The negative electrode active material can be capable of reversibly inserting or deintercalating lithium ions (Li). + Any material that can react with lithium ions to reversibly form lithium-containing compounds.

[0052] For example, negative electrode active materials may include: at least one carbon-based material selected from the group consisting of crystalline artificial graphite, crystalline natural graphite, amorphous hard carbon, low-crystallinity soft carbon, carbon black, acetylene black, Ketjen black, Super P, graphene, and fibrous carbon; Si-based materials; Li x Fe2O3 (0≤x≤1); Li x WO2 (0≤x≤1); metal composite oxides, such as Sn x Me 1- x Me′ y O z(Me: Mn, Fe, Pb, Ge; Me': Al, B, P, Si, Group 1, Group 2 and Group 3 elements of the Periodic Table of Elements, halogens; 0<x≤1; 1≤y≤3; 1≤z≤8); lithium metal; lithium alloy; silicon-based alloys; tin-based alloys; metal oxides, such as SnO, SnO2, PbO, PbO2, Pb2O3, Pb3O4, Sb2O3, Sb2O4, Sb2O5, GeO, GeO2, Bi2O3, Bi2O4 and Bi2O5; conductive polymers, such as polyacetylene; lithium cobalt nickel-based materials; titanium oxide; lithium titanium oxide, etc., but not limited thereto.

[0053] Furthermore, the negative electrode may include a negative electrode current collector and a coating containing metal-carbon composite particles located on the negative electrode current collector. This may represent an anode-free coating, meaning that it does not contain any negative electrode active material.

[0054] The negative electrode may be configured such that when the all-solid-state battery is charged, lithium ions reach the surface of the negative electrode current collector through the coating and are electrodeposited to form a lithium metal layer.

[0055] In the metal-carbon composite particles, carbon particles and metal particles may be attached to each other or coated on each other's surfaces, and may be physically or chemically bonded.

[0056] The carbon particles may include natural graphite, artificial graphite, hard carbon, soft carbon, carbon black, acetylene black, Ketjen black, channel black, furnace black, lamp black, thermal cracked carbon black, carbon nanotubes, fullerenes, carbon fibers and carbon fluoride.

[0057] The metal particles are lithiophilic metals, such as Ni, Cu, Ag, Au, Pt, Al, Zn or Bi, and may be one or a combination of two or more of the foregoing. By introducing the metal with the above-mentioned lithiophilicity, it is advantageous to form a stable and uniform lithium layer on the surface of the current collector.

[0058] The negative electrode can be prepared by mixing a binder solution and composite particles to prepare a slurry for forming the coating, then applying the slurry onto the negative electrode current collector and drying the slurry. In this case, the binder may be a conventional binder used in the art.

[0059] The solid electrolyte layer is formed as a layer containing a solid electrolyte. The solid electrolyte may be the solid electrolyte of Formula 1 as described above, or may be a solid electrolyte different from Formula 1. The solid electrolyte different from Formula 1 may comprise at least one selected from the group consisting of sulfide-based solid electrolytes, polymer-based solid electrolytes and oxide-based solid electrolytes, and preferably may comprise a sulfide-based solid electrolyte.

[0060] Sulfide solid electrolytes contain sulfur (S) and exhibit the ionic conductivity of metals belonging to Group I or Group II of the periodic table. They can include Li-PS type glasses or Li-PS type glass ceramics.

[0061] Specifically, sulfide-based solid electrolytes may include at least one selected from the group consisting of Li6PS5Cl, Li6PS5Br, Li6PS5I, Li2S-P2S5, Li2S-LiI-P2S5, Li2S-LiI-Li2O-P2S5, Li2S-LiBr-P2S5, Li2S-Li2O-P2S5, Li2S-Li3PO4-P2S5, Li2S-P2S5-SiS2, Li2S-P2S5-SnS, Li2S-P2S5-Al2S3, Li2S-GeS2, and Li2S-GeS2-ZnS. Preferably, it may include at least one selected from the group consisting of Li6PS5Cl, Li6PS5Br, and Li6PS5I. Li6PS5Cl, Li6PS5Br, and Li6PS5I may be argentite-germanium sulfide-type solid electrolytes. In addition, sulfide solid electrolytes can be in the form of trace element doping; for example, Li6PS5Cl can be doped with additional bromine (Br).

[0062] Polymer-based solid electrolytes are composites of lithium salts and polymer resins, specifically polymer electrolyte materials formed by adding polymer resins to solvated lithium salts, and can exhibit an activity of approximately 1 × 10⁻⁶. -7 S / cm or higher, preferably about 1 × 10⁻⁶ -5 Ionic conductivity above S / cm.

[0063] Non-limiting examples of polymer resins may include at least one of polyether polymers, polycarbonate polymers, acrylate polymers, polysiloxane polymers, phosphazene polymers, polyethylene derivatives, epoxyalkane derivatives such as polyethylene oxide, phosphate polymers, poly-stirred lysine, polyester sulfides, polyvinyl alcohol, polyvinylidene fluoride, and polymers containing ionic dissociative groups. Furthermore, polymer resins may include, for example, comb-like polymer resins, cross-linked polymer resins, and branched copolymers obtained by copolymerizing comonomers of amorphous polymers such as PMMA, polycarbonate, polysiloxane (PDMS), and / or phosphazene on the backbone of polyethylene oxide (PEO), and polymer electrolytes may include at least one of these as polymer resins.

[0064] In polymer solid electrolytes, the above-mentioned lithium salts are ionizable lithium salts and can be used with Li... + X - This indicates that the anion of this lithium salt is not particularly limited, but can be, for example, F.- Cl - ,Br - I - NO3 - N(CN)2 - BF4 - ClO4 - PF6 - (CF3)2PF4 - (CF3)3PF3 - (CF3)4PF2 - (CF3)5PF - (CF3)6P - CF3SO3 - CF3CF2SO3 - (CF3SO2)2N - (FSO2)2N - CF3CF2(CF3)2CO - (CF3SO2)2CH - (SF5)3C - (CF3SO2)3C - CF3(CF2)7SO3 - CF3CO2 - CH3CO2 - SCN - Or (CF3CF2SO2)2N - .

[0065] Oxide solid electrolytes can contain oxygen (O) and exhibit the ionic conductivity of metals belonging to Group I or Group II of the periodic table. For example, oxide solid electrolytes can contain compounds selected from LLTO groups, such as Li6La2CaTa2O. 12 Li6La2ANb2O 12 (A is Ca or Sr), Li2Nd3TeSbO 12 Li3BO 2.5 N 0.5 Li9SiAlO8, LAGP compounds, LATP compounds, Li 1+x Ti 2-x Al x Si y (PO4) 3-y (0≤x≤1,0≤y≤1), LiAl x Zr 2-x (PO4)3 (where 0 ≤ x ≤ 1, 0 ≤ y ≤ 1), LiTi x Zr 2-x(PO4)3 (0≤x≤1, 0≤y≤1), at least one selected from the group consisting of LISICON-type compounds, LIPON-type compounds, perovskite-type compounds, NASICON-type compounds and LLZO-type compounds.

[0066] The positive electrode active material layer of the positive electrode for an all-solid-state battery of the present invention comprises the solid electrolyte of formula 1. The solid electrolyte of formula 1 is configured such that 0≤d<0.3, d<e≤3, e≥7d, wherein Cl is contained in a trace amount, and X (Br or I) is contained in excess. Therefore, the contact area between the solid electrolyte of formula 1 and the positive electrode active material is increased, thereby reducing the porosity of the positive electrode, effectively forming ion conduction pathways, and improving the ionic conductivity and electrical conductivity of the positive electrode. Therefore, an all-solid-state battery comprising the positive electrode can achieve improved energy density.

[0067] [Example]

[0068] Hereinafter, the present invention will be described in more detail by way of examples, but these examples are provided for illustrative purposes only and are not intended to limit the scope of the present invention.

[0069] <Preparation of Positive Electrode for All-Solid-State Battery>

[0070] Example 1

[0071] A composition for forming a positive electrode active material layer was prepared, which comprises a positive electrode active material (NCM 811), a conductive material (carbon fiber), a solid electrolyte (Li6PS5Cl 0.1 Br 0.9 ) and a binder (polytetrafluoroethylene). The composition for forming a positive electrode active material layer is coated on a positive electrode current collector to produce a positive electrode having a positive electrode active material layer formed on the current collector.

[0072] Comparative Example 1

[0073] A positive electrode was produced in the same manner as in Example 1, except that Li6PS5Cl was used as the solid electrolyte.

[0074] Comparative Example 2

[0075] A positive electrode was produced in the same manner as in Example 1, except that Li6PS5Cl 0.5 Br 0.5 was used as the solid electrolyte.

[0076] Experimental Example 1. Porosity Measurement of Positive Electrode for All-Solid-State Battery

[0077] The porosity of the positive electrodes for all-solid-state batteries prepared in Example 1, Comparative Example 1 and Comparative Example 2 was measured. By stamping each positive electrode into a 2 × 2 cm 2The sample was then measured for weight and thickness to determine porosity, and the results were... Figure 1 As shown in the image.

[0078] Based on the porosity measurement results, the porosity of Example 1 was determined to be 12.1%, while the porosity of Comparative Example 1 was 14.3% and the porosity of Comparative Example 2 was 15.1%. That is, the porosity of the positive electrode for the all-solid-state battery of Example 1 is lower than that of Comparative Examples 1 and 2.

[0079] In Comparative Example 1, the solid electrolyte in the positive electrode active material layer does not contain X. In Comparative Example 2, d is 0.5 and e is 0.5. Therefore, the positive electrode active material layers in Comparative Examples 1 and 2 do not contain the solid electrolyte of Formula 1. As a result, since the contact between the positive electrode active material and the solid electrolyte is not increased, the positive electrodes for all-solid-state batteries in Comparative Examples 1 and 2 exhibit higher porosity compared to Example 1. On the other hand, since the positive electrode active material layer in Example 1 contains the solid electrolyte of Formula 1, the contact between the positive electrode active material and the solid electrolyte is increased, leading to a decrease in porosity.

[0080] Experimental Example 2. Measurement of Ion Conductivity and Electrical Conductivity of the Positive Electrode in an All-Solid-State Battery

[0081] The ionic conductivity and electrical conductivity of the positive electrodes for all-solid-state batteries prepared in Example 1, Comparative Example 1, and Comparative Example 2 were measured by electrochemical impedance spectroscopy (60°C, 0.01-10). 6 Ion conductivity and electrical conductivity were measured at Hz, and the results are shown in Table 1 below.

[0082] Table 1

[0083] According to the results shown in Table 1, the conductivity and ionic conductivity of the positive electrode for the all-solid-state battery of Example 1 are superior to those of Comparative Examples 1 and 2. As described in Experimental Example 1 above, the positive electrode active material layer of Comparative Examples 1 and 2 does not contain the solid electrolyte of Formula 1. Therefore, the contact between the positive electrode active material and the solid electrolyte is not increased, resulting in a decrease in the conductivity and ionic conductivity of the positive electrodes of Comparative Examples 1 and 2 compared to Example 1.

[0084] Since the positive electrode active material layer of Example 1 contains the solid electrolyte of Formula 1, the contact between the positive electrode active material and the solid electrolyte is increased, resulting in excellent conductivity and ion conductivity.

[0085] Experimental Example 3. Measurement of Discharge Capacity and Cycle Characteristics of the Positive Electrode of an All-Solid-State Battery

[0086] The discharge capacity and cycle characteristics of the positive electrodes for all-solid-state batteries prepared in Example 1, Comparative Example 1 and Comparative Example 2 were measured.

[0087] Discharge capacity and cycle characteristics were measured as follows: Each all-solid-state battery was charged to 4.25 V using a positive electrode at 0.33 C in CC-CV mode at 60°C, and then discharged to 3.0 V under constant current. Capacity retention after 50 charge-discharge cycles was used as the metric. The discharge capacity results are shown below. Figure 2 The cyclic characteristics results are shown in Figure 3 .

[0088] As previously described in Experimental Example 1, the positive electrode active material layers of Comparative Examples 1 and 2 do not contain the solid electrolyte of Formula 1. Therefore, based on the results of Experimental Examples 1 and 2, the positive electrodes for all-solid-state batteries of Comparative Examples 1 and 2 exhibit high porosity and low conductivity and ionic conductivity, while the positive electrode active material layer of Example 1, which contains the solid electrolyte of Formula 1, exhibits low porosity and excellent conductivity and ionic conductivity.

[0089] Therefore, the all-solid-state battery cathode of Example 1, with its low porosity and high conductivity and ionic conductivity, exhibits excellent results in terms of discharge capacity and cycle characteristics. In contrast, the all-solid-state battery cathodes of Comparative Examples 1 and 2, with their high porosity and low conductivity and ionic conductivity, show poorer discharge capacity and cycle characteristics compared to Example 1.

[0090] These results show that when the positive electrode active material layer includes the solid electrolyte of Formula 1, the contact between the positive electrode active material and the solid electrolyte of Formula 1 increases, which reduces the porosity of the positive electrode and improves its ionic conductivity and electrical conductivity. Furthermore, these effects improve the energy density of the positive electrode and the all-solid-state battery including it.

Claims

1. A positive electrode for an all-solid-state battery, comprising: a current collector; and a positive electrode active material layer disposed on the current collector, wherein the positive electrode active material layer comprises a positive electrode active material, a binder, and a solid electrolyte represented by Formula 1: [Formula 1] Li a P b S c Cl d X e wherein 4≤a≤7, 0≤b≤1, 3≤z≤5, 0≤d<0.3, d<e≤3, and X is Br or I.

2. The positive electrode for an all-solid-state battery according to claim 1, wherein, 0<d<0.3。 3. The positive electrode for an all-solid-state battery according to claim 2, wherein, e≥7d.

4. The positive electrode for an all-solid-state battery according to claim 1, wherein, 0.5≤e≤3。 5. The positive electrode for an all-solid-state battery according to claim 1, wherein, Based on the total weight of the positive electrode active material layer, the positive electrode active material layer comprises 65 wt% to 95 wt% of the positive electrode active material, 3 wt% to 30 wt% of the solid electrolyte represented by Formula 1, and 0.1 wt% to 5 wt% of the binder.

6. The positive electrode for an all-solid-state battery according to claim 1, wherein, The positive electrode active material layer further comprises a conductive material.

7. The positive electrode for an all-solid-state battery according to claim 6, wherein, Based on the total weight of the positive electrode active material layer, the content of the conductive material is more than 0 wt% to 5 wt%.

8. An all-solid-state battery, comprising: the positive electrode according to any one of claims 1 to 7; a negative electrode; and a solid electrolyte layer disposed between the positive electrode and the negative electrode.

9. The all-solid-state battery according to claim 8, wherein, the solid electrolyte of the solid electrolyte layer comprises a sulfide-based solid electrolyte.

10. The all-solid-state battery according to claim 9, wherein, said solid electrolyte is the same as or different from the solid electrolyte represented by Formula 1.

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