Solid electrolyte and all-solid-state battery comprising same

Abstract

The present invention relates to a positive electrode for an all-solid-state battery, the electrode having improved electrochemical properties as a result of a sulfide-based solid electrolyte having an argyrodite-type structure, thus having a Young's modulus of less than 20 GPa and reducing the porosity of the positive electrode to less than 20%.

Description

Solid electrolyte and all-solid-state battery including the same

[0001] The present application claims the benefit of priority based on Korean Patent Application No. 10-2024-0130941 filed September 26, 2024 and Korean Patent Application No. 10-2025-0127968 filed September 9, 2025, and includes all contents disclosed in the documents of said Korean patent applications as part of this specification.

[0002] The present invention relates to a solid electrolyte and an all-solid-state battery containing the same.

[0003] Although lithium-ion batteries have mainly been applied in small-scale fields such as mobile devices, laptops, and computers, recent research directions are expanding to medium and large-scale fields, and are gradually moving toward areas requiring high output, mainly in relation to energy storage systems (ESS) and electric vehicles (EV).

[0004] In the case of these medium-to-large lithium-ion batteries, unlike small ones, not only are the operating environments (e.g., temperature, shock) harsh, but a larger number of batteries must also be used; therefore, safety must be ensured along with excellent performance and a reasonable price.

[0005] Since most currently commercialized lithium-ion batteries utilize organic liquid electrolytes in which lithium salts are dissolved in flammable organic solvents, they carry potential risks of leakage, ignition, and explosion. In fact, as explosion accidents involving products using this technology are continuously being reported, it is an urgent matter to resolve these issues.

[0006] If this is to be resolved using safety devices, there is a risk of energy density loss due to the significant weight occupied by the devices, and fundamentally, there are inevitably limitations in overcoming safety issues as organic liquid electrolytes are used.

[0007] Based on this understanding, using a solid electrolyte to replace the organic liquid electrolyte is gaining attention as an alternative to overcome the aforementioned safety issues. However, since a solid electrolyte is used, additional solid electrolyte for the lithium ion conduction path must be mixed when manufacturing the cathode of an all-solid-state battery. Therefore, to achieve effective cell performance, the cathode active material, solid electrolyte, conductive material, and binder within the cathode need to have a structure optimized for performance.

[0008]

[0009] [Prior Literature]

[0010] [Patent Literature]

[0011] Chinese Patent Publication No. 117638001 (March 1, 2024)

[0012]

[0013] The objective of the present invention is to provide a cathode for an all-solid-state battery with improved electrochemical properties by applying a sulfide-based solid electrolyte having an argyrodite-type structure with a Young's modulus of less than 20 GPa and reducing the porosity of the cathode to less than 20%.

[0014] Another objective of the present invention is to provide an all-solid-state battery with improved output characteristics by applying the anode for the all-solid-state battery described above.

[0015] One embodiment of the present invention provides a positive electrode for an all-solid-state battery comprising a positive electrode active material, a solid electrolyte, a conductive material, and a binder, wherein the Young's modulus of the solid electrolyte is less than 20 GPa and the porosity of the positive electrode is less than 20%.

[0016] The Young's modulus of the above solid electrolyte may be greater than 10 GPa and less than 20 GPa.

[0017] The porosity of the above anode may be greater than 10% and less than 20%.

[0018] The above solid electrolyte is a sulfide-based solid electrolyte and may have an argyrodite-type structure.

[0019] The above anode may comprise 70% to 95% by weight of an anode active material, 4.8% to 29.8% by weight of a solid electrolyte, 0.1% to 5% by weight of a conductive material, and 0.1% to 5% by weight of a binder, based on the total weight of the anode.

[0020] The above sulfide-based solid electrolyte can be represented by the following chemical formula 1.

[0021] [Chemical Formula 1]

[0022] Li a P b S c Cl d X e

[0023] In the above Chemical Formula 1, P may be substituted or doped with Si, Ge, or Sn, S may be substituted or doped with O or Se, X is Br or I, and 4≤a≤7, 0≤b≤1, 3≤c≤5, and 0≤d <e≤3이다.

[0024] Another embodiment of the present invention provides a method for manufacturing a positive electrode for an all-solid-state battery, comprising the steps of: (1) mixing a positive electrode active material, a solid electrolyte, a conductive material, and a binder; and (2) kneading the mixture.

[0025] The above kneading can be performed by a kneader.

[0026] Another embodiment of the present invention provides a solid-state battery comprising a positive electrode, a negative electrode, and a solid electrolyte layer disposed between the positive electrode and the negative electrode, wherein the positive electrode comprises a positive electrode for the solid-state battery.

[0027] The cathode for an all-solid-state battery according to the present invention satisfies the condition that the Young's modulus of the solid electrolyte contained in the cathode is less than 20 GPa and the porosity of the cathode is less than 20%, thereby increasing the interfacial contact between the solid electrolyte and the cathode active material, which can improve the electrochemical characteristics and output characteristics of the all-solid-state battery.

[0028] Figure 1 is a graph showing the resistance of an all-solid-state battery including a positive electrode according to an embodiment of the present invention, measured using electrochemical impedance spectroscopy (EIS).

[0029] FIG. 2 is a graph showing the capacity retention of an all-solid-state battery including a positive electrode according to Example 3 and Comparative Example 3 of the present invention.

[0030] FIG. 3 is a graph showing the capacity retention rate of an all-solid-state battery including a positive electrode according to Example 3 and Comparative Example 4 of the present invention.

[0031] Figure 4 is a graph showing the capacity retention rate of an all-solid-state battery including a positive electrode according to Examples 3 and 4 of the present invention.

[0032] Embodiments of the present invention will be described in detail below. Prior to this, terms and words used in this specification and claims should not be interpreted as being limited to their ordinary or dictionary meanings. Instead, based on the principle that the inventor can appropriately define the concepts of terms to best describe their invention, they should be interpreted in a meaning and concept consistent with the technical spirit of the present invention. Therefore, the configurations described in the embodiments of this specification are merely one preferred embodiment of the present invention and do not represent all aspects of the technical spirit of the present invention. It should be understood that various equivalents and modifications capable of replacing them may exist at the time of filing this application.

[0033] Throughout this specification, when a part is described as 'comprising' a certain component, it means that, unless specifically stated otherwise, it does not exclude other components but may include additional components.

[0034] Furthermore, descriptions that specify components by limiting or adding them may be applied to all inventions unless there are special limitations, and are not limited to specific inventions.

[0035] In addition, throughout the description of the invention and claims of this application, items indicated in the singular include cases where they are plural unless otherwise noted.

[0036] In addition, throughout the description of the invention and the claims of the present invention, "or" includes "and" unless otherwise noted. Therefore, "comprising A or B" means all three of the above cases: including A, including B, or including both A and B.

[0037] In addition, all numerical ranges include the values ​​at both ends and all intermediate values ​​in between, unless explicitly stated to be excluded.

[0038]

[0039] Cathode for All-Solid-State Batteries

[0040]

[0041] A positive electrode for an all-solid-state battery according to the present invention may include a current collector and a positive electrode active material layer formed on at least one side of the current collector, and the positive electrode active material layer may include a positive electrode active material, a solid electrolyte, a conductive material, and a binder.

[0042] The porosity of the anode for an all-solid-state battery according to the present invention may be less than 20%. The porosity may be calculated using the true density of each anode material measured by He pycnometry (BEL-Pycno) after measuring the weight and thickness of the anode punched into a 13-pi electrode after isotropic pressing (500 MPa, 30 minutes). According to a specific embodiment of the present invention, the porosity of the anode for an all-solid-state battery may be greater than 3%, greater than 5%, greater than 10%, or greater than 15% within the above range, and may also be less than 20%, less than 18%, less than 15%, or less than 10%. For example, the porosity of the anode for an all-solid-state battery may be greater than 10% and less than 20%. By having a porosity within this range for the all-solid-state battery, the interfacial contact area between the solid electrolyte and the cathode active material described later can be improved, thereby enhancing the electrochemical performance of the cathode.

[0043] The elastic modulus, i.e., Young's modulus, of the solid electrolyte included in the cathode for an all-solid-state battery according to the present invention may be less than 20 GPa. The Young's modulus may be measured by a conventional Young's modulus measurement method, specifically using a dynamic mechanical analysis system (DMA800, TA Instruments). According to a specific embodiment of the present invention, the Young's modulus of the solid electrolyte may be in the range of greater than 3 GPa, greater than 5 GPa, greater than 10 GPa, or greater than 15 GPa within the above range, and may also be in the range of less than 20 GPa, less than 18 GPa, less than 15 GPa, or less than 10 GPa. For example, the Young's modulus of the solid electrolyte may be greater than 10 GPa and less than 20 GPa. By having a Young's modulus within this range, the contact between the solid electrolyte and the cathode material increases, thereby extending the conduction pathway and improving electrode output performance.

[0044] The cathode for an all-solid-state battery according to the present invention may have a Young's modulus of the solid electrolyte included in the cathode of less than 20 GPa and a porosity of the cathode of less than 20%. According to a specific embodiment of the present invention, the cathode may satisfy the above-described ranges of Young's modulus and cathode. By having the solid electrolyte included in the cathode for an all-solid-state battery have a Young's modulus within this range and the cathode have a porosity within this range, the components within the all-solid-state battery can have a structure optimized for performance realization, and the output characteristics of the battery can be improved by increasing the interfacial contact between the solid electrolyte and the cathode active material.

[0045] According to one embodiment of the present invention, the solid electrolyte included in the positive electrode for an all-solid-state battery may be a sulfide-based solid electrolyte and may be represented by the following chemical formula 1.

[0046] [Chemical Formula 1]

[0047] Li a P b S c Cl d X e

[0048] In the above Chemical Formula 1, P may be substituted or doped with Si, Ge, or Sn, S may be substituted or doped with O or Se, X is a halogen element, specifically Br or I, and 4≤a≤7, 0≤b≤1, 3≤c≤5, and 0≤d <e≤3이다.

[0049] In addition, preferably, the sulfide-based solid electrolyte is Li 5.5 PS 4.5 Cl 0.5 It may be a solid electrolyte having an azirodite-type structure comprising one or more selected from Br, Li6PS5Br, and Li6PS5I.

[0050] According to one embodiment of the present invention, a positive electrode for an all-solid-state battery may contain a solid electrolyte in a range of 4.8 to 29.8 weight% based on the total weight of the positive electrode. According to a specific embodiment of the present invention, the solid electrolyte may be included in a range of 4.8 weight% or more, 10 weight% or more, 15 weight% or more, or 20 weight% or more within the above range, and may also be included in a range of 29.8 weight% or less, 25 weight% or less, 20 weight% or less, or 15 weight% or less.

[0051] The positive electrode active material included in the positive electrode for an all-solid-state battery according to the present invention is not particularly limited as long as it is a material capable of reversibly absorbing and releasing lithium ions. For example, it may include one or more of a composite compound of a metal such as cobalt, manganese, nickel, iron, or a combination thereof; and lithium.

[0052] As a more specific example, a compound represented by any one of the following chemical formulas may be used as the core of the above-mentioned positive active material. Li a A 1-b R b D2 (wherein 0.90 ≤ a ≤ 1.8 and 0 ≤ b ≤ 0.5); Li a E 1-b R b O 2-c D c (In the above formula, 0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, and 0 ≤ c ≤ 0.05); LiE 2-b R b O 4-c D c (In the above equation, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05); Li a Ni 1-b-c Co b R c D α (In the above formula, 0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05 and 0 < α ≤ 2); Li a Ni1-b-c Co b R c O 2-α Z α (In the above formula, 0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, and 0 < α < 2); Li a Ni 1-b-c Co b R c O 2-α Z2 (wherein 0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05 and 0 < α < 2); Li a Ni 1-b-c Mn b R c D α (In the above formula, 0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, and 0 < α < 2); Li a Ni 1-b-c Mn b R c O 2-α Z α (In the above formula, 0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, and 0 < α < 2); Li a Ni 1-b-c Mn b R c O 2-α Z2 (wherein 0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05 and 0 < α < 2); Li a Ni b E c G d O2(wherein 0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.9, 0 ≤ c ≤ 0.5 and 0.001 ≤ d ≤ 0.1); Li a Ni b Co c Mn d GeO2(wherein 0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.9, 0 ≤ c ≤ 0.5, 0 ≤ d ≤ 0.5 and 0 ≤ e ≤ 0.1); Lia NiG b O2(wherein 0.90 ≤ a ≤ 1.8 and 0.001 ≤ b ≤ 0.1); Li a CoG b O2(wherein 0.90 ≤ a ≤ 1.8 and 0.001 ≤ b ≤ 0.1); Li a MnG b O2(wherein 0.90 ≤ a ≤ 1.8 and 0.001 ≤ b ≤ 0.1); Li a Mn2G b O4 (wherein 0.90 ≤ a ≤ 1.8 and 0.001 ≤ b ≤ 0.1); QO2; QS2; LiQS2; V2O5; LiV2O5; LiTO2; LiNiVO4; Li (3-f) J2(PO4)3(0 ≤ f ≤ 2); Li (3-f) Fe2(PO4)3(0 ≤ f ≤ 2); and LiFePO4.

[0053] In the above chemical formula, A is Ni, Co, Mn or a combination thereof; R is Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, a rare earth element or a combination thereof; D is O, F, S, P or a combination thereof; E is Co, Mn or a combination thereof; Z is F, S, P or a combination thereof; G is Al, Cr, Mn, Fe, Mg, La, Ce, Sr, V or a combination thereof; Q is Ti, Mo, Mn or a combination thereof; T is Cr, V, Fe, Sc, Y or a combination thereof; and J is V, Cr, Mn, Co, Ni, Cu or a combination thereof.

[0054] In one embodiment, the positive active material may have a particle size of about 0.01 μm to 50 μm and may have the form of a secondary particle formed by aggregating a plurality of particles.

[0055] According to one embodiment of the present invention, a positive electrode for an all-solid-state battery may contain a positive electrode active material in a range of 70 to 95 weight% based on the total weight of the positive electrode. According to a specific embodiment of the present invention, the positive electrode active material may be included in a range of 70 weight% or more, 75 weight% or more, 80 weight% or more, or 85 weight% or more within the above range, and may also be included in a range of 95 weight% or less, 90 weight% or less, 85 weight% or less, or 80 weight% or less.

[0056] The conductive material included in the cathode for an all-solid-state battery according to the present invention is not particularly limited as long as it has conductivity without causing chemical changes in the battery, and may include, for example, graphite such as natural graphite or artificial graphite; carbon black such as carbon black, acetylene black, Ketjen black, channel black, furnace black, lamp black, or thermal black; conductive fiber such as carbon fiber or metal fiber such as VGCF (Vapor grown carbon fiber); metal powder such as fluorinated carbon, aluminum, or nickel powder; conductive whiskey such as zinc oxide or potassium titanate; conductive metal oxide such as titanium oxide; or one or more mixtures selected from conductive materials such as polyphenylene derivatives.

[0057] According to one embodiment of the present invention, a cathode for an all-solid-state battery may contain a conductive material in a range of 0.01 to 10 weight% based on the total weight of the cathode. According to a specific embodiment of the present invention, the conductive material may be included in a range of 0.01 weight% or more, 0.1 weight% or more, 1 weight% or more, or 3 weight% or more within the above range, and may also be included in a range of 10 weight% or less, 8 weight% or less, 6 weight% or less, or 4 weight% or less. For example, the conductive material may be included in a range of 0.1 to 5 weight% based on the total weight of the cathode. If the conductive material is included in an amount greater than the upper limit, the ratio of the active material is low, resulting in a decrease in energy density; if it is included in an amount less than the lower limit, it fails to reach the desired level of electronic conductivity, thereby reducing the capacity development rate.

[0058] The binder included in the cathode for an all-solid-state battery according to the present invention is a component added considering the binding properties of the cathode active material, sulfide-based solid electrolyte, and conductive material for the all-solid-state battery cathode, and any polymer binder known to be usable for electrode formation in the technical field to which the present invention belongs may be used without any particular limitations.

[0059] Examples of such polymer binders include acrylic binders, polyvinylidene fluoride (PVDF) binders, polytetrafluoroethylene (PTFE) binders, or butadiene rubber binders such as nitrile butadiene rubber (NBR), and it goes without saying that various other polymer binders can also be used. The cathode for an all-solid-state battery may contain a binder in a range of 0.1 to 5 weight percent based on the total weight of the cathode. According to a specific embodiment of the present invention, the binder may be included in a range of 0.1 weight percent or more, 1 weight percent or more, 2 weight percent or more, or 3 weight percent or more within the above range, and may also be included in a range of 5 weight percent or less, 4 weight percent or less, 3 weight percent or less, or 2 weight percent or less.

[0060] The cathode for an all-solid-state battery according to the present invention may further include additives such as fillers, coating agents, dispersants, and ion conductivity aids, in addition to the cathode active material, solid electrolyte, conductive material, and binder described above. Known materials generally used in cathodes for all-solid-state batteries may be used as the fillers, coating agents, dispersants, ion conductivity aids, etc.

[0061] The thickness of the anode above may be, for example, 70 to 150 μm.

[0062]

[0063] Method for manufacturing a cathode for an all-solid-state battery

[0064]

[0065] The cathode for an all-solid-state battery according to the present invention can be manufactured according to methods widely known in the art, and while not limited to specific manufacturing methods, it may include both dry and wet processes. For example, in the case of a dry process, a cathode active material, a solid electrolyte, a conductive material, and a binder can be mixed and the mixture can be clumped together through a kneading process to manufacture an electrode. In addition, in the case of a wet process, a cathode active material, a solid electrolyte, a conductive material, and a binder can be mixed in a solvent to produce a slurry-type cathode composite, and this cathode composite can be applied to a cathode current collector to manufacture the electrode.

[0066] The above positive current collector is generally made with a thickness of 3 to 500 μm. Such a positive current collector is not particularly limited as long as it has high conductivity without causing chemical changes in the battery, and for example, stainless steel, aluminum, nickel, titanium, calcined carbon, or aluminum or stainless steel surface-treated with carbon, nickel, titanium, silver, etc. may be used. The current collector may also form fine irregularities on its surface to increase the adhesion of the positive active material, and various forms such as films, sheets, foils, nets, porous bodies, foams, and nonwoven fabrics are possible.

[0067] According to one embodiment of the present invention, a positive electrode for an all-solid-state battery can be manufactured by a dry process. The dry process may include (1) a step of mixing a positive electrode active material, a solid electrolyte, a conductive material, and a binder, and (2) a step of kneading the mixture. Kneading is a general term for the process of making the mixture into an electrode by kneading (kneading) the mixture, and can be performed by kneading the mixture directly with a mortar, using kneader equipment such as a single screw kneader, or using other tangential mixers (kneaders), intermeshing mixers (kneaders), etc.

[0068] If the equipment used during kneading changes, the applied torque energy also changes, which can result in the electrode structure being formed differently. Therefore, even when using compounds of the same material and composition, there may be differences in the porosity of the electrode. According to a specific embodiment of the present invention, by performing a kneading operation using a kneader, an anode having a porosity capable of exhibiting the desired effect of the present invention can be manufactured.

[0069]

[0070] All-solid-state battery

[0071]

[0072] Another embodiment of the present invention provides a solid-state battery comprising a positive electrode, a negative electrode, and a solid electrolyte layer disposed between the positive electrode and the negative electrode, wherein the positive electrode is a positive electrode for a solid-state battery as described above.

[0073] As the positive electrode included in the above-mentioned all-solid-state battery has been explained in detail above, the negative electrode and solid electrolyte included in the all-solid-state battery will be explained in detail below.

[0074] The solid electrolyte layer disposed between the anode and the cathode may include, for example, a sulfide-based solid electrolyte. The sulfide-based solid electrolyte may be of the same type as or different from the sulfide-based solid electrolyte included in the anode.

[0075] For specific details regarding sulfide-based solid electrolytes, refer to the anode section described above.

[0076] The Young's modulus of the solid electrolyte is, for example, 35 GPa or less, 30 GPa or less, 27 GPa or less, 25 GPa or less, 23 GPa or less, and 10 to 35 GPa, 15 to 35 GPa, 15 to 30 GPa, or 15 to 25 GPa. Since the solid electrolyte has an elastic modulus in this range, pressurization and / or sintering of the solid electrolyte is performed more easily.

[0077] The solid electrolyte layer further comprises, for example, a binder. The binder included in the solid electrolyte layer is, for example, styrene butadiene rubber (SBR), polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, etc., but is not limited to these, and any binder used in the relevant technical field is acceptable. The binder of the solid electrolyte layer may be of the same type as or different from the binder of the positive electrode active material layer and the negative electrode active material layer.

[0078] Next, the negative electrode of the all-solid-state battery may include a negative electrode current collector and a negative electrode active material layer.

[0079] The thickness of the negative electrode active material layer is, for example, 50% or less, 40% or less, 30% or less, 20% or less, 10% or less, or 5% or less of the thickness of the positive electrode active material layer. The thickness of the negative electrode active material layer is, for example, 1 μm to 20 μm, 2 μm to 10 μm, or 3 μm to 7 μm. If the thickness of the negative electrode active material layer is excessively thin, lithium dendrites formed between the negative electrode active material layer and the negative electrode current collector cause the negative electrode active material layer to collapse, making it difficult to improve the cycle characteristics of the all-solid-state battery. If the thickness of the negative electrode active material layer increases excessively, the energy density of the all-solid-state battery decreases, and the internal resistance of the all-solid-state battery caused by the negative electrode active material layer increases, making it difficult to improve the cycle characteristics of the all-solid-state battery.

[0080] The negative electrode active material layer includes, for example, a negative electrode active material that forms an alloy or compound with lithium.

[0081] The negative active material included in the negative active material layer has, for example, a particle form. The average particle size of the negative active material having a particle form is, for example, 4 μm or less, 3 μm or less, 2 μm or less, 1 μm or less, or 900 nm or less. The average particle size of the negative active material having a particle form is, for example, 10 nm to 4 μm or less, 10 nm to 3 μm or less, 10 nm to 2 μm or less, 10 nm to 1 μm or less, or 10 nm to 900 nm or less. By having the negative active material have an average particle size within this range, the reversible absorption and / or desorption of lithium during charging and discharging may be more facilitated. The average particle size of the negative active material is, for example, a volume-converted median diameter (D50) measured using a laser particle size distribution meter.

[0082] The cathode active material included in the cathode active material layer comprises, for example, one or more selected from carbon-based cathode active materials and metal or metalloid cathode active materials.

[0083] The carbon-based cathode active material is, in particular, amorphous carbon. Amorphous carbon is, for example, carbon black (CB), acetylene black (AB), furnace black (FB), ketjen black (KB), graphene, etc., but is not necessarily limited to these, and any material classified as amorphous carbon in the relevant technical field is acceptable. Amorphous carbon is carbon that does not have crystallinity or has very low crystallinity, and is distinguished from crystalline carbon or graphite-based carbon.

[0084] The metal or metalloid cathode active material comprises one or more selected from the group consisting of gold (Au), platinum (Pt), palladium (Pd), silicon (Si), silver (Ag), aluminum (Al), bismuth (Bi), tin (Sn), and zinc (Zn), but is not necessarily limited to these; any metal cathode active material or metalloid cathode active material that forms an alloy or compound with lithium in the relevant technical field is acceptable. For example, nickel (Ni) is not a metal cathode active material because it does not form an alloy with lithium.

[0085] The negative active material layer comprises one type of negative active material among these negative active materials, or comprises a mixture of multiple different negative active materials. For example, the negative active material layer comprises only amorphous carbon, or comprises one or more selected from the group consisting of gold (Au), platinum (Pt), palladium (Pd), silicon (Si), silver (Ag), aluminum (Al), bismuth (Bi), tin (Sn), and zinc (Zn). Alternatively, the negative active material layer comprises a mixture of amorphous carbon and one or more selected from the group consisting of gold (Au), platinum (Pt), palladium (Pd), silicon (Si), silver (Ag), aluminum (Al), bismuth (Bi), tin (Sn), and zinc (Zn). The mixing ratio of a mixture of amorphous carbon and silver (Ag), etc., is, for example, 10:1 to 1:2, 5:1 to 1:1, or 4:1 to 2:1 by weight, but is not necessarily limited to these ranges and is selected according to the required characteristics of the all-solid-state battery. By having the negative electrode active material with such a composition, the cycle characteristics of the all-solid-state battery are further improved.

[0086] The negative active material included in the negative active material layer comprises, for example, a mixture of first particles made of amorphous carbon and second particles made of a metal or metalloid. The metal or metalloid includes, for example, gold (Au), platinum (Pt), palladium (Pd), silicon (Si), silver (Ag), aluminum (Al), bismuth (Bi), tin (Sn), and zinc (Zn). Alternatively, the metalloid is a semiconductor. The content of the second particles is 8 to 60 wt%, 10 to 50 wt%, 15 to 40 wt%, or 20 to 30 wt% based on the total weight of the mixture. By having the second particles in this range, the cycle characteristics of the all-solid-state battery are further improved, for example.

[0087] The negative electrode active material layer includes, for example, a binder. The binder may be, for example, styrene-butadiene rubber (SBR), polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, vinylidene fluoride / hexafluoropropylene copolymer, polyacrylonitrile, polymethyl methacrylate, etc., but is not necessarily limited to these, and any binder used in the relevant technical field is acceptable. The binder may be composed of a single binder or a plurality of different binders.

[0088] By including a binder, the negative active material layer is stabilized on the negative current collector. Furthermore, cracking of the negative active material layer is suppressed despite volume changes and / or relative positional changes during the charge-discharge process. For example, if the negative active material layer does not include a binder, it is possible for the negative active material layer to easily detach from the negative current collector. In the portion where the negative active material layer detaches from the negative current collector, the negative current collector is exposed and comes into contact with the solid electrolyte layer, thereby increasing the likelihood of a short circuit. The negative active material layer is fabricated, for example, by applying a slurry in which the materials constituting the negative active material layer are dispersed onto the negative current collector and drying it. By including a binder in the negative active material layer, stable dispersion of the negative active material within the slurry is possible. For example, when applying the slurry onto the negative current collector using a screen printing method, it is possible to suppress screen clogging (e.g., clogging caused by aggregates of the negative active material).

[0089] The negative electrode current collector is composed of a material that does not react with, for example, lithium, that is, does not form either an alloy or a compound. The material constituting the negative electrode current collector may be, for example, copper (Cu), stainless steel, titanium (Ti), iron (Fe), cobalt (Co), and nickel (Ni), but is not necessarily limited to these; any material used as an electrode current collector in the relevant technical field is acceptable. The negative electrode current collector may be composed of one of the metals described above, or may be composed of an alloy or coating material of two or more metals. The negative electrode current collector is, for example, in the form of a plate or a foil.

[0090] The negative electrode active material layer may further include additives used in conventional all-solid-state batteries, such as fillers, dispersants, and ion conductors.

[0091] Meanwhile, the above-mentioned negative electrode may not contain a separate lithium metal, except for the lithium metal formed during charging. That is, the all-solid-state battery according to one embodiment of the present invention may be a negative electrode-free all-solid-state battery, and lithium may not be contained between the negative electrode current collector, the negative electrode active material layer, or the negative electrode active material layer and the solid electrolyte layer in the initial state or in the state after complete discharge.

[0092] For example, when an all-solid-state battery including such a negative electrode is overcharged, the negative active material contained in the negative active material layer and lithium ions that have migrated from the positive electrode may form an alloy or compound, thereby forming (precipitating) a metal layer with lithium as the main component on the negative electrode. The metal layer may be formed by precipitation between the negative current collector and the negative active material layer, inside the negative active material layer, or in both of these locations. When the metal layer is located between the negative current collector and the negative active material layer, the metal layer may be formed closer to the negative current collector layer than to the negative active material layer.

[0093] In a non-cathode all-solid-state battery according to one embodiment of the present invention, the negative electrode active material layer may include one or more lithium-affinity materials selected from the group consisting of silver (Ag), gold (Au), platinum (Pt), zinc (Zn), silicon (Si), magnesium (Mg), copper oxide (CuO), zinc oxide (ZnO), cobalt oxide (CoO), manganese monoxide (MnO), silicon dioxide (SiO2), titanium dioxide (TiO2), alumina (Al2O3), zinc peroxide (ZnO2), and lithium fluoride (LiF) as negative electrode active materials. However, it is not limited thereto, and any lithium-affinity material having similar physical properties or characteristics may be applied without special limitation.

[0094] In one embodiment of the present invention, the lithium-affinity material does not necessarily have to be uniformly present in the negative electrode active material layer, but may be localized on the negative current collector side within the negative electrode active material layer. In this case, a Li (lithium-affinity material) alloy may be formed into a metal layer by reacting with the localized layer of the lithium-affinity material within the negative electrode active material layer that has reached the vicinity of the negative current collector.

[0095] In addition, in the initial state without charging or discharging, the lithium-affinity material included in the negative electrode active material layer may be in the form of particles or films. When the lithium-affinity material exists in the form of particles, the average particle diameter (d50, diameter length or average diameter) of the lithium-affinity material may be 20 nm to 1 μm, but is not limited thereto.

[0096] Meanwhile, the above-mentioned negative electrode active material layer may also include a carbon material as a negative electrode active material in addition to a lithium-affinity material. Amorphous carbon may preferably be used as the carbon material included in the above-mentioned negative electrode active material layer. Specific examples of the above-mentioned amorphous carbon include amorphous carbon black (amorphous acetylene black, amorphous furnace black, amorphous Ketjen black), amorphous activated carbon, amorphous graphene, and combinations thereof. However, by positioning a carbon material with a relatively small particle size on the interface side in contact with the solid electrolyte layer among the negative electrode active material layers, the interface of the negative electrode active material layer in contact with the solid electrolyte layer can be made flatter. Based on 100 weight% of the total negative electrode active material included in the above-mentioned negative electrode active material layer, the total negative electrode active material other than the lithium-affinity material may be 50 weight% or more, for example, 70 weight% or more. The content of the negative electrode active material other than the lithium-affinity material can be measured by the same method as the method for measuring the content of the above-mentioned lithium-affinity material.

[0097] Meanwhile, the above-mentioned negative current collector may be positioned at the outermost edge with respect to the stacking direction, facing the opposite side of the negative active material layer that does not come into contact with the solid electrolyte layer. However, if the battery includes a bicell or higher structure, it may be positioned at a location other than the outermost edge with respect to the stacking direction.

[0098] The above-mentioned negative current collector may be in the form of a plate or a foil. The above-mentioned negative current collector may include a material that does not react with lithium, that is, does not form any alloy or compound with lithium. Examples of materials constituting the above-mentioned negative current collector include copper, aluminum, stainless steel, titanium, iron, cobalt, and nickel. Furthermore, the above-mentioned negative current collector may be composed of one of these metals, or may be composed of an alloy or clad material of two or more metals.

[0099] An all-solid-state battery can be manufactured, for example, by manufacturing a positive electrode, a negative electrode, and a solid electrolyte layer, respectively, and then stacking these layers.

[0100] The present invention provides a battery module including the all-solid-state battery as a unit cell, a battery pack including the battery module, and a device including the battery pack as a power source.

[0101] Specific examples of the above-mentioned device include, but are not limited to, power tools that are powered by an electric motor; electric vehicles including electric vehicles (EV), hybrid electric vehicles (HEV), and plug-in hybrid electric vehicles (PHEV); electric two-wheeled vehicles including electric bicycles (E-bike) and electric scooters (E-scooter); electric golf carts; and power storage systems.

[0102] Specific embodiments of the present invention are presented below. However, the embodiments described below are merely for the purpose of specifically illustrating or explaining the present invention and do not limit the present invention. Furthermore, details not described herein can be sufficiently technically inferred by a person skilled in the art, so their description is omitted.

[0103]

[0104] <Example: Cathode for an all-solid-state battery and manufacture of an all-solid-state battery including the same>

[0105]

[0106] Example 1

[0107] Lithium nickel-cobalt-manganese (LiNi) as a positive electrode active material 0.8 Co 0.1 Mn 0.1O2), Li6PS5Br having an agitide-type structure with a Young's modulus of 19.2 GPa as a sulfide-based solid electrolyte, carbon nanofiber (CNF) as a conductive material, and polytetrafluoroethylene (PTFE) as a binder were sequentially added to a container in a weight ratio of 80:15:2.5:2.5. Each time a component was added, a Lab Blender was used to mix the mixture five times for 30 seconds at 2000 RPM to prepare an anode mixture. The mixture was then mixed for 15 minutes using a kneader at 100°C with a shear force applied at 10 RPM to prepare the anode mixture. A free-standing film was prepared from the anode mixture using a two-roll mil machine at 25°C.

[0108]

[0109] Example 2

[0110] In the above Example 1, as a sulfide-based solid electrolyte, Li having an azyrodite-type structure with a Young's modulus of 19.7 GPa was used. 5.5 PS 4.5 Cl 0.5 A positive electrode for an all-solid-state battery was prepared in the same manner as in Example 1 above, except that Br was used.

[0111]

[0112] Example 3

[0113] First, 6g of carbon black, 2g of Ag, 9.33g of polyvinylidene fluoride (PVdF) binder, and 7.67g of N-methyl-2-pyrrolidone (NMP) solution were placed in a Thinky mixer container and mixed 12 times for 3 minutes at 2,000 rpm. Afterward, 5g of N-methyl-2-pyrrolidone solution was added and mixed 5 times for 3 minutes at 2,000 rpm to prepare a negative electrode active material slurry, which was then coated onto a SUS foil and dried to manufacture a negative electrode.

[0114] Next, the anode prepared in Example 1 was positioned to face the cathode prepared above, and a sulfide-based solid electrolyte (Li2S-P2S5) was interposed between them to prepare an all-solid-state battery. Subsequently, the prepared cell was pressurized for 30 minutes under a condition of 500 MPa using a warm isostatic pressure device.

[0115]

[0116] Example 4

[0117] In the above Example 3, an all-solid-state battery was manufactured in the same manner as in Example 3, except that the anode prepared in Example 2 was used.

[0118]

[0119] Comparative Example 1

[0120] In the above Example 1, a positive electrode for an all-solid-state battery was prepared in the same manner as in Example 1, except that Li6PS5Cl with a Young's modulus of 21 GPa was used as the sulfide-based solid electrolyte.

[0121]

[0122] Comparative Example 2

[0123] In the above Example 1, Li having a Young's modulus of 19.7 GPa was used as the sulfide-based solid electrolyte. 5.5 PS 4.5 Cl 0.5 A positive electrode for an all-solid-state battery was prepared in the same manner as in Example 1, except that Br was used and mixing was performed for 10 minutes using mortar instead of a kneader for the mixture.

[0124]

[0125] Comparative Example 3

[0126] In the above Example 3, an all-solid-state battery was manufactured in the same manner as in Example 3, except that the anode prepared in Comparative Example 1 was used.

[0127]

[0128] Comparative Example 4

[0129] In the above Example 3, an all-solid-state battery was manufactured in the same manner as in Example 3, except that the anode prepared in Comparative Example 2 was used.

[0130]

[0131] <Experimental Example>

[0132]

[0133] Experimental Example 1: Evaluation of Solid Electrolyte and Electrode Characteristics

[0134] The Young's modulus of the solid electrolytes used in Examples 1 and 2 and Comparative Examples 1 and 2 is described, and Table 1, which summarizes the results of measuring the electronic conductivity, ionic conductivity, and porosity of the positive electrodes for all-solid-state batteries in Examples 1 and 2 and Comparative Examples 1 and 2, is shown below.

[0135] Electron conductivity and ionic conductivity were measured as follows. An electrode assembly was prepared by placing the anodes of Examples 1 and 2 and Comparative Examples 1 and 2 between current collectors and compressing them. Subsequently, the prepared assembly was subjected to pressure treatment at 500 MPa for 30 minutes using a Warm Isostatic Pressure device. Afterward, the electron conductivity and ionic conductivity were measured in the SoC 0 state within the range of 800 kHz to 10 mHz using Electrochemical Impedance Spectroscopy (EIS).

[0136] The porosity was calculated using the true density of each anode material measured by He pycnometry (BEL-Pycno) after measuring the weight and thickness of the anode stamped with a 13 pi electrode isotropically pressurized (500 MPa, 30 min). To ensure the reliability of the experimental values, five electrodes were measured and the average value was calculated.

[0137]

[0138] Comparative Example 1 Comparative Example 2 Example 1 Example 2 Young's Modulus (GPa) 21 19.7 19.2 19.7 Porosity (%) 15.4 20.2 14.0 15.1 Electron Conductivity (mS / cm) 8.2 × 10⁻⁶ -5 7.3×10 -5 3.6×10 -4 2.7×10 -4 Ionic conductivity (mS / cm) 1.0×10⁻⁶ -4 7.5×10 -5 2.4×10 -4 1.8×10 -4

[0139]

[0140] From Table 1 above, it can be seen that the Young's modulus of the solid electrolytes in Examples 1 and 2 is less than 20 GPa and the porosity of the electrodes is less than 20%, and that the electrodes in Examples 1 and 2 showed improved electronic conductivity and ionic conductivity compared to Comparative Examples 1 and 2.

[0141]

[0142] Experimental Example 2: Electrode EIS Measurement Evaluation

[0143] An electrode assembly was manufactured by positioning the anodes of Examples 1 and 2 and Comparative Examples 1 and 2 between current collectors and compressing them. Subsequently, the manufactured assembly was subjected to pressure treatment at 500 MPa for 30 minutes using a Warm Isostatic Pressure device.

[0144] Using electrochemical impedance spectroscopy (EIS), resistance was measured in the SoC 50 state in the range of 800 kHz to 10 mHz. The measured resistance is shown in Fig. 1. From Fig. 1, it can be seen that the resistance value of the battery containing the positive electrodes of Examples 1 and 2 is significantly lower than that of the battery containing the positive electrodes of Comparative Examples 1 and 2.

[0145]

[0146] Experimental Example 3: Evaluation of Dose Retention Rate

[0147] The capacity retention rate (%) was evaluated for the all-solid-state batteries according to Examples 3 and 4 and Comparative Examples 3 and 4. The capacity retention rate is calculated by dividing the capacity at discharge by the capacity at charge. Specifically, using the all-solid-state batteries, the discharged batteries were charged at 0.1C under conditions of 25°C. Afterward, discharge was performed at the same C-rate as during charging.

[0148] For each battery, the capacity during charging and discharging was evaluated to calculate the capacity retention rate. Using the method described above, the capacity retention rate was calculated by varying the C-rate to 0.1C, 0.33C, 0.5C, 1.0C, and 0.1C, respectively. The results are shown in Figures 2 to 4.

[0149] From FIGS. 2 to 4, it can be seen that the capacity retention rate of the all-solid-state battery according to Examples 3 and 4 is higher than that of the all-solid-state battery according to Comparative Examples 3 and 4. Specifically, the capacity retention rate of the all-solid-state battery according to Examples 3 and 4 is 95% or higher at all measured C-rates. On the other hand, the capacity retention rate of the all-solid-state battery according to Comparative Examples 3 and 4 is lower than that of Example 1 under conditions of 0.33C or higher.

[0150]

[0151] Although preferred embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements by those skilled in the art using the basic concept of the present invention as defined in the following claims also fall within the scope of the present invention.

Claims

1. A cathode for an all-solid-state battery comprising a cathode active material, a solid electrolyte, a conductive material, and a binder, A cathode for an all-solid-state battery having a Young's modulus of less than 20 GPa of the solid electrolyte and a porosity of less than 20% of the cathode.

2. In Claim 1, A positive electrode for an all-solid-state battery having a Young's modulus of the above-mentioned solid electrolyte greater than 10 GPa and less than 20 GPa.

3. In Claim 1, A positive electrode for an all-solid-state battery having a porosity of more than 10% and less than 20%.

4. In Claim 1, The above solid electrolyte is a sulfide-based solid electrolyte and is a positive electrode for an all-solid-state battery having an argyrodite-type structure.

5. In Claim 1, The above-described positive electrode comprises, based on the total weight of the positive electrode, 70% to 95% by weight of a positive electrode active material, 4.8% to 29.8% by weight of a solid electrolyte, 0.1% to 5% by weight of a conductive material, and 0.1% to 5% by weight of a binder, for use as a positive electrode for an all-solid-state battery.

6. In Claim 1, A positive electrode for an all-solid-state battery, wherein the above-mentioned sulfide-based solid electrolyte is represented by the following chemical formula 1: [Chemical Formula 1] Li a P b S c Cl d X e In the above Chemical Formula 1, P may be substituted or doped with Si, Ge, or Sn, S may be substituted or doped with O or Se, X is Br or I, and 4≤a≤7, 0≤b≤1, 3≤c≤5, and 0≤d <e≤3이다.

7. A method for manufacturing a positive electrode for an all-solid-state battery according to Claim 1, (1) A step of mixing a positive electrode active material, a solid electrolyte, a conductive material and a binder; and (2) A step of kneading the above mixture; a method for manufacturing a positive electrode for an all-solid-state battery.

8. In Claim 7, A method for manufacturing a positive electrode for an all-solid-state battery in which the kneading in step (2) above is performed by a kneader.

9. Anode; cathode; and It includes a solid electrolyte layer disposed between the anode and the cathode, and The above anode comprises the anode for an all-solid-state battery according to claim 1. All-solid-state battery.

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