Cathode and all-solid-state battery comprising same

Abstract

The present invention relates to a cathode comprising a cathode active material layer and an all-solid-state battery comprising same, the cathode active material layer comprising a cathode active material, a sulfide-based solid electrolyte, a conductive material composite, and a fibrillized binder, wherein the conductive material composite includes: a core part containing a carbon-based conductive material; and a coating part disposed on at least a portion of the core part and containing polymer nanoparticles, the polymer nanoparticles being composed of a copolymer of polyvinylidene fluoride (PVDF) and a comonomer, the comonomer being at least one selected from the group consisting of hexafluoropropylene (HFP), chlorotrifluoroethylene (CTFE), hexafluoroacetone (HFA), 1-hydropentafluoropropylene (HPFP), tetrafluoroethylene (TFE), and trifluoroethylene (TrFE). According to the present invention, a cathode and an all-solid-state battery comprising same can be provided wherein the cathode has excellent ionic / electrical conductivity and charge and discharge performance as well as superb mechanical properties, such as tensile strength.

Description

Anode and all-solid-state battery containing the same

[0001] This application claims the benefit of priority from Republic of Korea Patent Application No. 2023-0162162, filed November 21, 2023, the entire disclosure of which is incorporated herein by reference. The present invention relates to a cathode and an all-solid-state battery comprising the same.

[0002] Customer demand for high-energy density and high-stability secondary batteries is rapidly increasing. To meet this demand, technological development for various all-solid-state battery electrodes is continuing. Among these, sulfide-based all-solid-state batteries, which offer high ionic conductivity and theoretically high energy density, are attracting significant attention.

[0003] In the sulfide-based all-solid-state battery system, lithium ion conduction does not occur through a liquid electrolyte as in the existing lithium-ion battery system, so a sulfide-based solid electrolyte with high ion conductivity is added during electrode manufacturing to improve lithium ion conductivity.

[0004] When the all-solid-state battery is repeatedly charged and discharged, the volume of the positive electrode active material expands and contracts, leading to the continuous collapse of the contact interface between the positive electrode active material and the sulfide-based solid electrolyte. To address this issue, it is necessary to introduce a polymer binder that suppresses side reactions in the sulfide-based solid electrolyte while also exhibiting superior binding properties. However, because these polymer binders have low electrical conductivity, their content in the electrode must be continuously reduced to improve performance.

[0005] The present invention is intended to solve the above problems, and aims to provide a positive electrode having excellent ionic / electrical conductivity and charge / discharge performance, as well as excellent mechanical properties such as tensile strength, and an all-solid-state battery including the positive electrode.

[0006] One aspect of the present invention relates to a positive electrode including a positive electrode active material layer, wherein the positive electrode active material layer includes a positive electrode active material, a sulfide-based solid electrolyte, a conductive composite material, and a fibrous binder, wherein the conductive composite material includes a core portion including a carbon-based conductive material and a coating portion positioned on at least a portion of the core portion, and includes polymer nanoparticles, wherein the polymer nanoparticles are a copolymer of polyvinylidene fluoride (PVDF) and a comonomer, and the comonomer is at least one selected from the group consisting of hexafluoropropylene (HFP), chlorotrifluoroethylene (CTFE), hexafluoroacetone (HFA), 1-hydropentafluoropropylene (HPFP), tetrafluoroethylene (TFE), and trifluoroethylene (TrFE).

[0007] In one embodiment, the fiberizing binder may be characterized as being polytetrafluoroethylene (PTFE).

[0008] In one embodiment, the cathode active material layer may be characterized by including 1.2 parts by weight or less of a fiber binder per 100 parts by weight of the cathode active material layer.

[0009] In one embodiment, the weight ratio of polymer nanoparticles to the conductive composite material may be 5 to 50 wt%.

[0010] In one embodiment, the polymer nanoparticles may be characterized in that the polymerization ratio between polyvinylidene fluoride (PVDF) and the comonomer is in the range of 99:1 to 75:25.

[0011] In one embodiment, the carbon-based conductive material may be characterized by being at least one selected from the group consisting of graphite, carbon black, or carbon fiber.

[0012] In one embodiment, the BET surface area of ​​the carbon-based conductive material is 10 m 2 / g or less can be characterized.

[0013] In one embodiment, the carbon-based conductive material may be characterized by having an average length of 5 to 20 μm.

[0014] In one embodiment, the sulfide-based solid electrolyte is Li2S-P2S5-Li2O, Li2S-P2S5-Li2O-LiI, Li2S-LiBr-LiI-P2S5, Li2S-SiS2, Li2S-SiS2-LiI, Li2S-SiS2-LiBr, Li2S-SiS2-LiCl, Li2S-SiS2-B2S3-LiI, Li2S-SiS2-Li3PO4, Li2S-SiS2-Li p MO q (p,q are positive numbers, M is one of P, Si, Ge, B, Al, Ga, and In), Li2S-SiS2-P2S5-LiI,Li2S-P2S5,Li2S-P2S5-LiX (X is a halogen element), Li2S-B2S3,Li2S-P2S5-Z m S n (m,n are positive numbers), Z is one of Ge, Zn or Ga, L i2 S-GeS2,Li 7-x PS 6-x Cl x (0≤x≤2), Li 7-x PS 6-x Br x (0≤x≤2) and Li 7-x PS 6-x I x It can be characterized by being at least one selected from the group including (0≤x≤2).

[0015] In one embodiment, the anode of the present invention may be characterized as being a dry anode.

[0016] Another aspect of the present invention relates to an all-solid-state battery comprising a positive electrode, a solid electrolyte layer, and a negative electrode, wherein the positive electrode comprises a positive electrode active material layer, the positive electrode active material layer comprises a positive electrode active material, a sulfide-based solid electrolyte, a conductive composite material, and a fibrous binder, the conductive composite material comprises a core portion comprising a carbon-based conductive material and a coating portion positioned on at least a portion of the core portion, and comprising polymer nanoparticles, the polymer nanoparticles being a copolymer of polyvinylidene fluoride (PVDF) and a comonomer, and the comonomer being at least one selected from the group consisting of hexafluoropropylene (HFP), chlorotrifluoroethylene (CTFE), hexafluoroacetone (HFA), 1-hydropentafluoropropylene (HPFP), tetrafluoroethylene (TFE), and trifluoroethylene (TrFE).

[0017] In one embodiment, the solid electrolyte layer may be characterized by including at least one selected from the group consisting of a sulfide-based solid electrolyte, an oxide-based solid electrolyte, and a halide-based solid electrolyte.

[0018] According to the present invention, it is possible to provide a positive electrode having excellent ionic / electrical conductivity and charge / discharge performance, as well as excellent mechanical properties such as tensile strength, and an all-solid-state battery including the positive electrode.

[0019] Terms or words used in this specification and claims should not be interpreted as limited to their usual or dictionary meanings, but should be interpreted as meanings and concepts that conform to the technical idea of ​​the present invention, based on the principle that the inventor can appropriately define the concept of the term to explain his or her own invention in the best way.

[0020] Accordingly, the configuration of the embodiments described in this specification is only one of the most preferred embodiments of the present invention and does not represent all of the technical ideas of the present invention, so it should be understood that various equivalents and modified examples that can replace them may exist at the time of filing this application.

[0021] In this specification, singular expressions include plural expressions unless the context clearly indicates otherwise.

[0022] When a part in this specification is said to “comprise” a certain component, this does not exclude other components unless specifically stated to the contrary, but rather means that other components may be included. Thus, for example, a composition comprising compound A may include compounds other than A. However, the term “comprise” also encompasses, as a specific embodiment thereof, the more restrictive meanings of “consisting essentially / essentially of” and “consisting of,” so that, for example, “a composition comprising compound A” may also consist (essentially / essentially) of compound A.

[0023] In this connection, it should be understood that terms such as “have” or “have” as used herein are intended to specify the presence of a feature, number, step, component, or combination thereof, but do not preclude the possibility of the presence or addition of one or more other features, numbers, steps, components, or combinations thereof.

[0024] When it is said in this specification that any layer is located “on” or “between” any other layer, this includes not only cases where any layer is in contact with any other layer, but also cases where another layer or material, etc., exists between the two layers.

[0025] Where an amount, concentration, or other value or parameter is given herein as a range, a preferred range, or an enumeration of an upper preferred value and a lower preferred value, this should be understood to specifically disclose any range that can be formed by any pair of any upper range limit or preferred value and any lower range limit or preferred value, regardless of whether the range is separately disclosed. Where a range of numerical values ​​is recited herein, unless otherwise stated, e.g., there is no limiting term such as greater than, less than, etc., the range is intended to include the endpoint values ​​and all integers and fractions within the range. The scope of the present invention is not intended to be limited to the specific values ​​recited when defining a range.

[0026] Among the properties mentioned in this specification, if the measurement temperature affects the property, the property is measured at room temperature unless otherwise specified. The term "room temperature" refers to the natural temperature without heating or cooling, and may mean, for example, any temperature within the range of about 10°C to 30°C, or about 23°C or about 25°C. In addition, unless otherwise specified, the unit of temperature in this specification is ℃.

[0027] In addition, among the properties mentioned in this specification, if the measurement pressure affects the property, the property is measured at normal pressure, i.e., atmospheric pressure (approximately 1 atm), unless otherwise specified.

[0028] In this specification, “all-solid-state battery” may mean an all-solid-state secondary battery, and may also be referred to as a cell, secondary battery, or battery.

[0029] In this specification, if at least one of the positive electrode, the solid electrolyte layer, and / or the negative electrode includes a sulfide-based solid electrolyte, it may be referred to as a “sulfide-based all-solid-state battery.”

[0030] A first aspect of the present invention relates to an anode.

[0031] The present invention relates to a positive electrode including a positive electrode active material layer, wherein the positive electrode active material layer includes a positive electrode active material, a sulfide-based solid electrolyte, a conductive composite material, and a fibrous binder, wherein the conductive composite material includes a core portion including a carbon-based conductive material and a coating portion located on at least a portion of the core portion, and includes polymer nanoparticles, wherein the polymer nanoparticles are a copolymer of polyvinylidene fluoride (PVDF) and a comonomer, and the comonomer is at least one selected from the group consisting of hexafluoropropylene (HFP), chlorotrifluoroethylene (CTFE), hexafluoroacetone (HFA), 1-hydropentafluoropropylene (HPFP), tetrafluoroethylene (TFE), and trifluoroethylene (TrFE).

[0032] The above-mentioned fiber-forming binder may be characterized as, for example, polytetrafluoroethylene (PTFE). The PTFE has two phase transition temperatures of 19°C and 30°C, and when stress is applied between polymer powders at 19°C or higher, fiber-forming properties are developed, allowing for uniform binding of other electrode elements. In this way, PTFE has unique fiber-forming properties, allowing for uniform binding of electrode materials in a solvent-free system. In the present specification, the term "solvent-free system" may refer to a system in which materials such as an active material, an electrolyte, a conductive material, and / or a binder are mixed without a solvent during the manufacture of an electrode slurry, for example.

[0033] The positive electrode of the present invention includes the above-described fibrous binder in the positive electrode active material layer, thereby taking advantage of the high ionic conductivity of a sulfide-based solid electrolyte and the soft physical properties that enable room-temperature processing, while controlling side reactions such as the generation of hydrogen sulfide gas due to the high moisture sensitivity of the sulfide-based solid electrolyte.

[0034] The positive electrode of the present invention may be characterized by comprising, for example, 1.2 parts by weight or less of the fibrous binder relative to 100 parts by weight of the positive electrode active material layer. In another example, the positive electrode of the present invention may be characterized by comprising, relative to 100 parts by weight of the positive electrode active material layer, 1.15 parts by weight or less, 1.1 parts by weight or less, 1.05 parts by weight or less, or 1 part by weight or less of the fibrous binder, or 0.1 parts by weight or more, 0.3 parts by weight or more, 0.5 parts by weight or more, 0.7 parts by weight or more, or 0.9 parts by weight or more of the fibrous binder. As the binder content in the positive electrode active material layer increases, the binding characteristics improve, but the conductivity may decrease, resulting in a deterioration in the performance of the battery. That is, the tensile strength and conductivity of the positive electrode active material layer have been known to be in a trade-off relationship. However, the present invention has confirmed that it is possible to have excellent tensile strength and conductivity while reducing the binder content in the positive electrode active material layer by introducing a conductive composite material, etc.

[0035] The conductive composite material may include, for example, a core portion including a carbon-based conductive material and a coating portion positioned on at least a portion of the core portion and including polymer nanoparticles. In the present specification, "the coating portion is positioned on at least a portion of the core portion" may mean, for example, that the coating portion covers 10% or more, 20% or more, 30% or more, 40% or more, 50% or more, 60% or more, 70% or more, 80% or more, 90% or more, 95% or more, or 100% of the surface of the core portion, or covers 95% or less, 90% or less, 80% or less, 70% or less, 60% or less, 50% or less, 40% or less, 30% or less, 20% or less, or 10% or less. In the present specification, "the coating portion covers the surface of the core portion" may mean that the coating portion is formed on the core portion with a thickness of at least 100 nm or more. The core portion may contain, for example, 70 wt% or more, 80 wt% or more, 90 wt% or more, 95 wt% or more, or 100 wt% of a carbon-based conductive material. The coating portion may contain, for example, 70 wt% or more, 80 wt% or more, 90 wt% or more, 95 wt% or more, or 100 wt% of a polymer nanoparticle.

[0036] The above polymer nanoparticles may be, for example, a copolymer of polyvinylidene fluoride (PVDF) and a comonomer, and the comonomer may be at least one selected from the group consisting of hexafluoropropylene (HFP), chlorotrifluoroethylene (CTFE), hexafluoroacetone (HFA), 1-hydropentafluoropropylene (HPFP), tetrafluoroethylene (TFE), and trifluoroethylene (TrFE). The positive electrode of the present invention may have excellent conductivity by including the copolymer of polyvinylidene fluoride (PVDF) and a comonomer as described above in the positive electrode active material layer. In addition, the comonomer may be used without limitation as long as it is at least one of the examples described above, but in terms of increasing the elongation of the positive electrode active material layer and ensuring ease of processing through the same, it may be preferable that it is hexafluoropropylene (HFP).

[0037] The weight ratio of the polymer nanoparticles to the conductive composite material may be, for example, 5 to 50 wt%. In other examples, the weight ratio of the polymer nanoparticles to the conductive composite material may be 10 wt% or more, 15 wt% or more, 45 wt% or less, 40 wt% or less, 35 wt% or less, 30 wt% or less, or 25 wt% or less. The positive electrode of the present invention, by including the conductive composite material having the above characteristics in the positive electrode active material layer, can have excellent mechanical properties even with a small binder content, and can improve ionic and / or electrical conductivity. This effect can be further improved by further controlling the characteristics of the polymer nanoparticles described below.

[0038] In the above polymer nanoparticles, the polymerization ratio between the polyvinylidene fluoride (PVDF) and the comonomer may be, for example, within a range of 99:1 to 75:25, but is not limited thereto. In other examples, in the above polymer nanoparticles, the polymerization ratio between the polyvinylidene fluoride (PVDF) and the comonomer may be within a range of 97:3 to 80:20, or within a range of 95:5 to 85:15.

[0039] The above carbon-based conductive material may be characterized by being at least one selected from the group consisting of, for example, graphite; carbon black such as acetylene black, Ketjen black, channel black, furnace black, lamp black, and thermal black; or carbon fiber; In terms of reducing the formation of an interface with a sulfide-based solid electrolyte and controlling the decomposition phenomenon of the electrolyte during an electrochemical reaction, it may be preferable that the carbon-based conductive material be carbon fiber.

[0040] The BET specific surface area of ​​the above carbon-based conductive material is, for example, 10 m 2 / g or less. The BET specific surface area may be measured by a known method. In another example, the BET specific surface area of ​​the carbon-based conductive material is 9 m 2 / g or less, 8 m 2 / g or less, 7 m 2 / g or less, 6 m 2 / g or less, 5 m 2 / g or less, 4 m 2 / g or less, 3 m 2 / g or less, 2 m 2 / g or less or 1 m 2 / g or less, or 0.1 m 2 / g or more, 0.5 m 2 / g or more, 1 m 2 / g or more, 2 m 2 / g or more, 3 m 2 / g or more, 4 m 2 / g or more or 5 m2 / g or more. By controlling the BET specific surface area of ​​the carbon-based conductive material as described above, the decomposition phenomenon of the sulfide-based solid electrolyte can be controlled.

[0041] The average length of the carbon-based conductive material may be, for example, 5 to 20 ㎛. In other examples, the average length of the carbon-based conductive material may be 7 ㎛ or more, 9 ㎛ or more, or 11 ㎛ or more, or 19 ㎛ or less, 18 ㎛ or less, 17 ㎛ or less, 16 ㎛ or less, 15 ㎛ or less, 14 ㎛ or less, or 13 ㎛ or less. By controlling the average length of the carbon-based conductive material included in the core portion of the conductive material composite material as described above, a conductive path between the positive electrode active materials within the positive electrode active material layer can be sufficiently secured, thereby improving electrical conductivity while also improving dispersibility.

[0042] The anode of the present invention may be characterized, for example, in that the weight ratio of the conductive composite material to the fibrous binder is 0.01 to 100. In another example, the anode of the present invention may be characterized in that the weight ratio of the conductive composite material to the fibrous binder is 0.05 or more, 0.1 or more, 0.5 or more, 5 or more, 10 or more, or 50 or more, or 90 or less, 50 or less, 10 or less, 5 or less, 0.5 or less, 0.1 or less, or 0.05 or less.

[0043] The above sulfide-based solid electrolyte is, for example, Li2S-P2S5-Li2O, Li2S-P2S5-Li2O-LiI, Li2S-LiBr-LiI-P2S5, Li2S-SiS2, Li2S-SiS2-LiI, Li2S-SiS2-LiBr, Li2S-SiS2-LiCl, Li2S-SiS2-B2S3-LiI, Li2S-SiS2-Li3PO4, Li2S-SiS2-Li p MO q(p,q are positive numbers, M is one of P, Si, Ge, B, Al, Ga, and In), Li2S-SiS2-P2S5-LiI,Li2S-P2S5,Li2S-P2S5-LiX (X is a halogen element), Li2S-B2S3,Li2S-P2S5-Z m S n (m,n are positive numbers), Z is one of Ge, Zn or Ga, L i2 S-GeS2,Li 7-x PS 6-x Cl x (0≤x≤2), Li 7-x PS 6-x Br x (0≤x≤2) and Li 7-x PS 6-x I x It can be characterized by being at least one selected from the group including (0≤x≤2).

[0044] A sulfide-based solid electrolyte can be manufactured by treating starting materials such as Li2S and P2S5 by a melting rapid cooling method or a mechanical milling method. In addition, a heat treatment can be performed after such treatment. The solid electrolyte can be in an amorphous, crystalline, or mixed state. In the present invention, the sulfide-based solid electrolyte can be, for example, one that includes sulfur (S), phosphorus (P), and lithium (Li) as at least constituent elements among the above-mentioned sulfide-based solid electrolyte materials.

[0045] The above sulfide-based solid electrolyte is, for example, Li 7-x PS 6-x Cl x (0≤x≤2), Li 7-x PS 6-x Br x (0≤x≤2), and Li 7-x PS 6-x I xIt may be an argyrodite-type compound including at least one selected from (0≤x≤2). In particular, the sulfide-based solid electrolyte may be an argyrodite-type compound including at least one selected from Li6PS5Cl, Li6PS5Br, and Li6PS5I.

[0046] The density of the above-mentioned argyrodite-type solid electrolyte may be, for example, 1.5 to 2.5 g / cc. Since the above-mentioned argyrodite-type solid electrolyte has a density of 1.5 g / cc or more, the internal resistance of the all-solid-state secondary battery is reduced, and penetration of the solid electrolyte by Li can be effectively suppressed.

[0047] The elastic modulus of the above sulfide-based solid electrolyte may be, for example, 15 to 45 GPa.

[0048] The positive electrode of the present invention may be characterized, for example, in that the weight ratio of the sulfide-based solid electrolyte to the conductive composite material is 0.01 to 100. In another example, the positive electrode of the present invention may be characterized in that the weight ratio of the sulfide-based solid electrolyte to the conductive composite material is 0.05 or more, 0.1 or more, 0.5 or more, 5 or more, 10 or more, or 50 or more, or 90 or less, 50 or less, 10 or less, 5 or less, 0.5 or less, 0.1 or less, or 0.05 or less.

[0049] The anode of the present invention may be characterized, for example, as a dry anode. As used herein, a "dry anode" refers to an anode manufactured without using a solvent, and the dry anode may contain 1 wt% or less, 0.1 wt% or less, 0.001 wt% or less of a solvent, or may not contain any solvent at all.

[0050] The positive electrode of the present invention may further include, for example, other conductive materials other than the conductive material composite material in the positive electrode active material layer. The other conductive materials may be different from the conductive material composite material, and in particular, may be different in that they do not include the above-described coating portion or do not include polymer nanoparticles having the above-described characteristics in the coating portion. The other conductive materials may be, for example, graphite, carbon black, acetylene black, Ketzen black, carbon fibers, carbon nanotubes, or metal powders, but are not limited thereto. Any conductive material that can be introduced into the positive electrode active material layer may be used without limitation as long as it does not impede the purpose of the present invention.

[0051] The above-described positive electrode active material reversibly intercalates and deintercalates lithium ions. The positive electrode active material may be, but is not limited to, lithium transition metal oxides such as lithium cobalt oxide (LCO), lithium nickel oxide, lithium nickel cobalt oxide, lithium nickel cobalt aluminum oxide (NCA), lithium nickel cobalt manganese oxide (NCM), lithium manganate, lithium iron phosphate, nickel sulfide, copper sulfide, lithium sulfide, iron oxide, or vanadium oxide, and any material used as a positive electrode active material in the art may be used. The positive electrode active materials may be used alone or in combination of two or more.

[0052] The above lithium transition metal oxide is, for example, Li a A 1-b B b D2 (in the above formula, 0.90≤a≤1, and 0≤b≤0.5); Li a Ni 1-b-c Co b B c O 2-αF2 (in the above formula, 0.90≤a≤1, 0≤b≤0.5, 0≤c≤0.05, 0 <α<2); Li a Ni 1-b-c Mn b B c D α (In the above formula, 0.90≤a≤1, 0≤b≤0.5, 0≤c≤0.05, 0≤α≤2); Li a Ni 1-b-c Co b B c D α (In the above formula, 0.90≤a≤1, 0≤b≤0.5, 0≤c≤0.05, 0<α≤2); Li a E 1-b B b O 2-c D c (In the above formula, 0.90≤a≤1, 0≤b≤0.5, 0≤c≤0.05); LiE 2-b B b O 4-c D c (In the above formula, 0≤b≤0.5, 0≤c≤0.05); Li a Ni 1-b-c Co b B c O 2-α F α (In the above formula, 0.90≤a≤1, 0≤b≤0.5, 0≤c≤0.05, 0<α<2); Li a CoG b O2 (in the above formula, 0.90≤a≤1, 0.001≤b≤0.1); Li a MnG b O2 (in the above formula, 0.90≤a≤1, 0.001≤b≤0.1); Li a Mn2G b O4 (in the above formula, 0.90≤a≤1, 0.001≤b≤0.1); Li a Ni 1-b-c Mn b B c O 2-α F α (In the above formula, 0.90≤a≤1, 0≤b≤0.5, 0≤c≤0.05, 0<α<2); Li a Ni 1-b-cMn b B c O 2-α F2 (in the above formula, 0.90≤a≤1, 0≤b≤0.5, 0≤c≤0.05, 0<α<2); Li a Ni b E c G d O2 (in the above formula, 0.90≤a≤1, 0≤b≤0.9, 0≤c≤0.5, 0.001≤d≤0.1); Li a Ni b Co c Mn d G e O2 (in the above formula, 0.90≤a≤1, 0≤b≤0.9, 0≤c≤0.5, 0 ≤d≤0.5, 0.001≤e≤0.1); Li a NiG b O2 (in the above formula, 0.90≤a≤1, 0.001≤b≤0.1); QO2;QS2;LiQS2;V2O5;LiV2O5;LiIO2;LiNiVO4;Li (3- f) J2(PO4)3(0≤f≤2); Li (3-f)Fe2(PO4)3(0≤f≤2); It may be a compound represented by any one of the chemical formulas of LiFePO4. In this compound, A is Ni, Co, Mn, or a combination thereof; B 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; F 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; I is Cr, V, Fe, Sc, Y, or a combination thereof; J may be V, Cr, Mn, Co, Ni, Cu, or a combination thereof. A compound having a coating layer added to the surface of this compound may be used as the positive electrode active material, or a mixture of the above-mentioned compound and the compound having a coating layer added may be used. The coating layer added to the surface of such compounds may contain, for example, a lithium ion conductive oxide. The lithium ion conductive oxide may be, for example, LiNbO3, Li4Ti5O. 12 , Li3PO4, etc., but are not limited thereto. The compound forming the coating layer may be amorphous or crystalline. The method for forming the coating layer may include, for example, spray coating, dipping, etc., but may be selected without limitation within a range that does not adversely affect the properties of the positive electrode active material.

[0053] When the above-mentioned cathode active material is a ternary lithium transition metal oxide such as NCA or NCM and contains nickel (Ni), it may be possible to increase the capacity density of the all-solid-state battery and reduce metal dissolution of the cathode active material in a charged state. Accordingly, the cycle characteristics of the all-solid-state battery in a charged state may be improved.

[0054] The shape of the above-mentioned positive electrode active material may be, for example, a spherical particle shape, such as an elliptical sphere. The particle size of the positive electrode active material is not particularly limited and may be within the range applicable to positive electrode active materials of conventional all-solid-state secondary batteries. The content of the positive electrode active material is also not particularly limited and may be within the range applicable to positive electrodes of conventional all-solid-state secondary batteries.

[0055] In addition to the above-mentioned positive electrode active material layer, the positive electrode active material layer may further include additives such as fillers, coating agents, dispersants, and ion conductive assistants, and these additives may be used without limitation as long as they are known materials generally used in electrodes of all-solid-state batteries.

[0056] The positive electrode of the present invention may further include, for example, a positive electrode current collector.

[0057] As the positive electrode current collector, any known metal that can be used as a current collector for an all-solid-state battery can be used. The positive electrode current collector may be, for example, a plate, mesh, or foil made of copper (Cu), nickel (Ni), aluminum (Al), vanadium (V), gold (Au), platinum (Pt), chromium (Cr), iron (Fe), zinc (Zn), indium (In), germanium (Ge), lithium (Li), magnesium (Mg), stainless steel, titanium (Ti), cobalt (Co), or an alloy thereof. The positive electrode current collector may be omitted in some cases.

[0058] The positive electrode of the present invention may have, for example, a ratio of tensile strength (MPa) to the content (wt%) of the fibrous binder included in the positive electrode active material layer of 0.1 MPa / wt% or more. The tensile strength may be measured in a manner according to an evaluation example described below. In another example, the positive electrode of the present invention may have a ratio of tensile strength to the content of the fibrous binder included in the positive electrode active material layer of 0.11 MPa / wt% or more, 0.12 MPa / wt% or more, or 0.13 MPa / wt% or more, and the upper limit is not particularly limited, but may be about 1 MPa / wt% or less, or 0.5 MPa / wt% or less.

[0059] The positive electrode of the present invention has, for example, a ratio of electrical conductivity (S / cm) to the content (weight %) of the fibrous binder included in the positive electrode active material layer of 3.5.E. -05 (S / cm) / weight% or more. The electrical conductivity may be measured in a manner according to the evaluation example described below. In another example, the positive electrode of the present invention has a ratio of the electrical conductivity (S / cm) to the content (weight%) of the fibrous binder included in the positive electrode active material layer of 4.E. -05 (S / cm) / weight% or more, 4.5.E -05 (S / cm) / weight% or more, 5.E -05 (S / cm) / weight% or more, 5.5.E -05 (S / cm) / weight% or more, 6.E -05 (S / cm) / weight% or more or 6.5.E -05 (S / cm) / weight% or more, and the upper limit is not specifically limited, but 20.E -05 (S / cm) / weight% or less, 15.E -05 (S / cm) / weight% or less or 10.E -05 (S / cm) / weight% or less.

[0060] The positive electrode of the present invention has, for example, a ratio of ionic conductivity (S / cm) to the content (weight %) of the fibrous binder included in the positive electrode active material layer of 2.5.E. -05(S / cm) / weight% or more. The ionic conductivity may be measured in a manner according to the evaluation example described below. In another example, the positive electrode of the present invention has a ratio of the ionic conductivity (S / cm) to the content (weight%) of the fibrous binder included in the positive electrode active material layer of 3.E. -05 (S / cm) / weight% or more, 3.5.E -05 (S / cm) / weight% or more, 4.E -05 (S / cm) / weight% or more, 4.5.E -05 (S / cm) / weight% or more or 5.E -05 (S / cm) / weight% or more, and the upper limit is not specifically limited, but 20.E -05 (S / cm) / weight% or less, 15.E -05 (S / cm) / weight% or less or 10.E -05 (S / cm) / weight% or less.

[0061] The second aspect of the present invention relates to an all-solid-state battery.

[0062] Matters relating to the first aspect of the present invention may be equally applied to matters relating to the second aspect unless specifically stated otherwise.

[0063] The present invention relates to an all-solid-state battery comprising a positive electrode, a solid electrolyte layer, and a negative electrode, wherein the positive electrode comprises a positive electrode active material layer, the positive electrode active material layer comprises a positive electrode active material, a sulfide-based solid electrolyte, a conductive composite material, and a fibrous binder, the conductive composite material comprises a core portion comprising a carbon-based conductive material and a coating portion positioned on at least a portion of the core portion, and comprising polymer nanoparticles, the polymer nanoparticles being a copolymer of polyvinylidene fluoride (PVDF) and a comonomer, and the comonomer being at least one selected from the group consisting of hexafluoropropylene (HFP), chlorotrifluoroethylene (CTFE), hexafluoroacetone (HFA), 1-hydropentafluoropropylene (HPFP), tetrafluoroethylene (TFE), and trifluoroethylene (TrFE).

[0064] The above solid electrolyte layer may include, but is not limited to, a sulfide-based solid electrolyte, an oxide-based solid electrolyte, or a halide-based solid electrolyte, and may be any electrolyte commonly used in an all-solid-state battery. The sulfide-based solid electrolyte included in the solid electrolyte layer may be, for example, at least one of the examples of the sulfide-based solid electrolyte included in the above-described positive electrode active material layer, and may be the same as or different from the sulfide-based solid electrolyte included in the positive electrode active material layer. The oxide-based solid electrolyte may be, for example, at least one of a Garnet-type solid electrolyte, a Nasicon-type solid electrolyte, a LISICON-type solid electrolyte, or a perovskite-type solid electrolyte. Specifically, the oxide-based solid electrolyte may be Li7La3Zr2O 12 , the above Li7La3Zr2O 12 Doped with elements such as Al, Y, Ga, Ta, Nb, etc. instead of Li, or the above Li7La3Zr2O 12Ga in the place of Li, La, and Zr elements +3 -Sc +3 Multi-doped ones, etc. are used; those coated with materials such as Al2CO3, Ge, ZnO, etc. on the surface are used; Na 1+x Zr2Si2P 3-X O 12 (0≤x≤3), LiM2(PO4)3(M=Zr,Ti,Ge),Li 1+x Al x M 2-x (PO4)3(0 <x<2,M=Zr,Ti,Ge)또는 상기 Al 대신 Y, La, Sc 등의 산화수가 +3인 원자를 도핑하거나 Sr, Mg, Ca 등의 산화수가 +2인 원자를 도핑한 것 등이 사용되거나; xLi3AO 4- (1-x)Li4BO4(A:P,As,V, etc., B:Si,Ge,Ti, etc.) or Li3BO3, etc. added thereto; or Li 3x La 2 / 3-x □ 1 / 3- 2x TiO3(LLTO,0 <x<0.16,□는 공공(vacancy)), La 0.57-2x / 3 Sr x Li 0.3 TiO3, etc. can be used, but are not limited thereto. The halide-based solid electrolyte includes Li2ZrCl6,Li 2+x Zr 1-x M x Cl6(M=Fe,Cr,V) and Na2ZrCl6 can be used, but are not limited thereto.

[0065] The shape of the solid electrolyte may be, for example, a particle type. In addition, the average particle diameter (D50) of the solid electrolyte may be, for example, in the range of 0.5 to 4 μm. The solid electrolyte may be used singly or in combination of two or more. If the solid electrolyte layer includes two or more solid electrolytes, the two or more solid electrolytes may be mixed and used in one layer, or a separate layer including each solid electrolyte may be formed to form a multilayer structure, or the respective solid electrolytes may be mixed and the mixing ratios may be the same or different to form a separate layer to form a multilayer structure. In the present specification, the average particle diameter (D50) may mean a diameter at which the cumulative volume of the particles is half (50%) of the total volume when the particle diameters of the particles measured by laser diffraction scattering particle diameter distribution measurement are arranged in descending order.

[0066] The solid electrolyte layer may further contain, for example, a binder. The binder may be, for example, an aqueous binder, an organic binder, or a combination thereof. The binder may be, for example, a polymer including polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, diacetyl cellulose, polyvinylidene fluoride, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, ethylene oxide, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene, fluoride, polyethylene, polypropylene, styrene-butadiene rubber, acrylate styrene-butadiene rubber, epoxy resin, nylon, or a combination thereof. The aqueous binder may be, for example, styrene butadiene rubber, carboxymethyl cellulose, or a combination thereof. The organic binder may be, for example, polytetrafluoroethylene, polyvinylidene fluoride, or a combination thereof, but is not limited thereto, and any known binder may be used without limitation as long as it does not impede the purpose of the present invention. The solid electrolyte layer may contain, for example, 5 wt% or less of the binder.

[0067] The thickness of the above solid electrolyte layer is not particularly limited, but may typically be within the range of 0.1 ㎛ to 1 mm.

[0068] The all-solid-state battery of the present invention may include a negative electrode.

[0069] The above negative electrode may, in one example, include a negative electrode active material layer. The negative electrode active material layer may include, for example, a negative electrode active material, and may optionally further include a solid electrolyte, a conductive material, and / or a binder.

[0070] The above negative active material is, for example, lithium, lithium alloy, carbon, silicon, silicon alloy or Li4Ti5O 12 (LTO), or the lithium, lithium alloy, carbon, silicon, silicon alloy or Li4Ti5O 12(LTO) and an alloy with at least one metal selected from the group consisting of Sn, Ge, and Al.

[0071] The above-mentioned solid electrolyte, conductive material and / or binder, etc. may be one of the types included in the above-mentioned positive electrode or solid electrolyte layer, but are not limited thereto, and any solid electrolyte, conductive material and / or binder used in the relevant technical field may be possible. The solid electrolyte, conductive material and / or binder included in the negative electrode active material layer may be the same as or different from the solid electrolyte, conductive material and / or binder included in the positive electrode active material layer, solid electrolyte layer, etc.

[0072] The above-mentioned negative active material layer may also further include, for example, other additives. These additives may be used without limitation as long as they are known materials generally used in electrodes of all-solid-state batteries.

[0073] The negative electrode may further include a negative electrode current collector. The negative electrode current collector may be a known metal that can be used as a current collector of an all-solid-state battery. The negative electrode current collector may be, for example, a material that does not form an alloy or compound with lithium. The negative electrode current collector may be, for example, selected from the group consisting of copper (Cu), nickel (Ni), aluminum (Al), vanadium (V), gold (Au), platinum (Pt), magnesium (Mg), iron (Fe), titanium (Ti), cobalt (Co), chromium (Cr), zinc (Zn), germanium (Ge), indium (In), and stainless steel, but is not limited thereto. Any material used as an electrode current collector in the relevant technical field may be used as long as it does not impede the purpose of the present invention. The negative electrode current collector may be composed of one of the above-mentioned metals, or may be composed of an alloy or a coating material of two or more metals. The above negative electrode collector may be, for example, in the form of a plate, mesh, or foil, but is not limited thereto.

[0074] In another example, when the negative electrode uses lithium or a lithium alloy as a negative electrode active material, the negative electrode may include lithium or a lithium alloy as a negative electrode active material layer during the battery manufacturing process (from the initial manufacturing), or a lithium layer may be formed during the charging process without forming a separate negative electrode active material layer during the battery manufacturing process.

[0075] In the above battery manufacturing process, if a separate negative active material layer is not formed, the all-solid-state battery of the present invention may include a non-cathode coating layer between the solid electrolyte layer and the negative current collector, or, if there is no negative current collector, on the surface of the non-cathode coating layer opposite to the solid electrolyte layer.

[0076] In this specification, the term "anode-free coating layer" means a coating layer formed between an anode current collector and a solid electrolyte layer, or on one side of a solid electrolyte layer when an anode current collector is absent, in an all-solid-state battery in which lithium is absorbed into the anode-free coating layer during charging and the charge capacity of the anode-free coating layer is exceeded, lithium is deposited between the anode current collector and the anode-free coating layer, or in the case where there is no anode current collector, on the side of the anode-free coating layer opposite to the solid electrolyte layer, to form a metal layer, and in which lithium in the anode-free coating layer and the lithium metal layer is ionized and moves toward the cathode during discharge, the coating layer may be different from the aforementioned anode active material layer in its composition and operating mechanism. The anode-free coating layer can act as a protective layer for the lithium metal layer by covering the lithium metal layer during the charging process and can suppress the precipitation and growth of lithium dendrites, thereby suppressing short-circuiting and capacity reduction of the all-solid-state battery and improving performance, etc.

[0077] The above-described non-anode coating layer may include, for example, amorphous carbon. The amorphous carbon included in the non-anode coating layer may be, for example, at least one selected from the group consisting of carbon black, acetylene black, furnace black, Ketjen black, and graphene, but is not limited thereto. Any amorphous carbon that can be used in a non-anode all-solid-state battery may be used without limitation.

[0078] The above-described non-cathode coating layer may further include, for example, a lithium-affinity element that forms an alloy or compound with lithium. The lithium-affinity element may be, for example, at least one metal, metalloid element, or a combination thereof 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).

[0079] The particle size of the lithium-affinity element may be, for example, in the range of 10 to 1000 nm. The particle size may refer to a maximum particle size, a minimum particle size, or an average particle size. In other examples, the particle size of the lithium-affinity element may be 20 nm or more, 30 nm or more, 40 nm or more, or 50 nm or more, or 500 nm or less, 400 nm or less, 300 nm or less, 200 nm or less, or 100 nm or less.

[0080] The above-described non-cathode coating layer may further include, for example, a binder. The binder may be selected from the binders mentioned as being included in the aforementioned positive electrode active material layer, solid electrolyte layer, negative electrode active material layer, etc., or may be any known binder without limitation.

[0081] The above-mentioned negative electrode may further optionally include a negative current collector on one side of the non-cathode coating layer, for example, and the negative current collector may be used without limitation as the above-mentioned one.

[0082] When the all-solid-state battery includes a non-anode coating layer, the all-solid-state battery may further include a thin film including an element capable of forming an alloy with lithium, for example. The thin film may be included between the negative electrode current collector and the non-anode coating layer, or on at least one surface of both surfaces of the non-anode coating layer when there is no negative electrode current collector. The element capable of forming an alloy with lithium may be, for example, gold, silver, zinc, tin, indium, silicon, aluminum, bismuth, etc., but is not limited thereto, and any element capable of forming an alloy with lithium in the art may be used. The thin film may be composed of one of the examples above or may be composed of various types of alloys. When the all-solid-state battery of the present invention further includes such a thin film, the cycle characteristics of the all-solid-state battery may be further improved.

[0083] The thickness of the above thin film may be, for example, 1 to 800 nm, 10 to 700 nm, 50 to 600 nm, or 100 to 500 nm. The above thin film may be formed by, for example, a vacuum deposition method, a sputtering method, a plating method, etc., but is not limited thereto, and any method capable of forming a thin film in the relevant technical field may be used.

[0084] When including the above-described non-cathode coating layer, the all-solid-state battery may further include a metal and / or a metal layer thereof including lithium or a lithium alloy, for example, between the negative electrode current collector and the non-cathode coating layer, on one side of the non-cathode coating layer opposite to the solid electrolyte layer, and / or within the non-cathode coating layer, by charging. The lithium alloy may be, but is not limited to, a Li-Al alloy, a Li-Sn alloy, a Li-In alloy, a Li-Ag alloy, a Li-Au alloy, a Li-Zn alloy, a Li-Ge alloy, a Li-Si alloy, etc., and any lithium alloy used in the art may be used. The metal or metal layer included between the negative electrode current collector and the non-cathode coating layer, and / or within the non-cathode coating layer may be composed of one of these alloys, lithium, or may be composed of multiple types of alloys.

[0085] The thickness of the metal layer including the lithium or lithium alloy may be, for example, in a range of 1 to 1000 μm, 1 to 500 μm, 1 to 200 μm, 1 to 150 μm, 1 to 100 μm or 1 to 50 μm. The thickness needs to be controlled as described above so that the metal layer can perform its role as a lithium storage well and improve cycle characteristics.

[0086] The metal layer may be formed by deposition, for example, between the negative current collector and the non-anode coating layer, or on the surface of the non-anode coating layer opposite to the solid electrolyte layer among the two sides of the non-anode coating layer, by charging after assembling the all-solid-state battery. When the metal layer is formed by charging after assembling the all-solid-state battery, the region between the negative current collector and the non-anode coating layer, or on the surface of the non-anode coating layer opposite to the solid electrolyte layer among the two sides of the non-anode coating layer, may be, for example, a lithium-free region that does not contain lithium in the initial state or the post-discharge state of the all-solid-state battery.

[0087] Hereinafter, the present invention will be described in detail by way of examples to specifically illustrate the disclosure of the present invention and its intended functions and effects, as described above. However, these examples may be modified in various ways, and the scope of this specification is not construed as being limited to these examples. It is emphasized that these examples are provided to represent the present invention and to provide a more concrete explanation to those skilled in the art.

[0088] Manufacturing example.

[0089] After dispersing PVDF-HFP in an organic solvent at a certain weight ratio, a spray coater is used to coat carbon fiber (BET 10m 2 / g or less, and the average fiber length is 12㎛. As a result, PVDF-HFP nanoparticles were coated on the surface of the carbon fiber, and a conductive composite material containing 20 parts by weight of the PVDF-HFP nanoparticles per 100 parts by weight of the conductive composite material was obtained.

[0090] Example 1.

[0091] Positive electrode active material: sulfide-based solid electrolyte: conductive agent: binder were mixed in a weight ratio of 78:19.5:1.5:1 for powder mixing. Specifically, the positive electrode active material and the sulfide-based solid electrolyte were quantified in powder form, mixed for 15 minutes using an agate mortar in a dry room environment, and then the conductive agent was quantified and added to the above mixture, mixed for an additional 15 minutes. Then, the binder was quantified and added to the above mixture, and further mixed to obtain a mixed powder. The mixed powder was fiberized using a mortar and calendered on a roller to obtain 6 mAh / cm 2 A positive electrode including a positive electrode active material layer of a level was manufactured.

[0092] At this time, LiNi is used as the positive electrode active material. 0.8 Co 0.1 Mn 0.1 O2(NCM), Li6PS5Cl, an argyrodite type crystal, was used as a sulfide-based solid electrolyte, a conductive composite material manufactured according to the above manufacturing example was used as a conductive material, and PTFE (601X, Chemours) was used as a binder. The sum of the weights of the PVDF-HFP nanoparticles included in the conductive composite material and the binder was 1.3 parts by weight per 100 parts by weight of the mixed powder.

[0093] Comparative Example 1.

[0094] As a conductive material, carbon fiber (BET 10m) was used instead of the conductive material composite material of the manufacturing example. 2 / g or less, fiber length average 12㎛) and the positive electrode active material: sulfide-based solid electrolyte: conductive material: binder was used in the weight ratio of 78:19.5:1.2:1.3, except that the same method as in the example was used to obtain 6 mAh / cm 2 A positive electrode including a positive electrode active material layer of a level was manufactured.

[0095] Evaluation Example 1. Evaluation of mixed powder characteristics

[0096] The powder flow stability of the mixed powders of Example 1 and Comparative Example 1 was evaluated using a powder rheology evaluation tool of a rheometer (Discovery HR-20, TA instruments). The powder rheology tool was mounted on the rheometer installed in a dry room, and the mixed powder was filled into the cup mounted on the rheology tool. Thereafter, a powder flow test was performed under room temperature and pressure conditions.

[0097] As a result, as shown in Table 1 below, it was confirmed that the mixed powder of Example 1 had superior flow stability compared to the mixed powder of Comparative Example 1. This is expected to be because the conductive composite material according to the present invention effectively binds the positive electrode active material and the sulfide-based solid electrolyte.

[0098] [Table 1]

[0099]

[0100] (At this time, for each example and comparative example, measure twice and use the average value as the result value in Table 1 above.)

[0101] Here, the confined stability index (%) is the ratio of the flow energy measured in the direction entering the cup when the blade mounted on the rheometer rotates at a constant speed and moves up and down in the cup containing the powder, which means the ratio of the energy value in the last rotation to the energy value in the first rotation. On the other hand, the unconfined stability index (%) is the ratio of the flow energy measured in the direction going up the cup when the blade mounted on the rheometer rotates at a constant speed and moves up and down in the cup containing the powder, which also means the ratio of the energy value in the last rotation to the energy value in the first rotation.

[0102] Evaluation Example 2. Evaluation of anode conductivity

[0103] The positive electrodes of Example 1 and Comparative Example 1 were punched out to a size of 18 mm x 18 mm, and packaged with Al foil as positive electrode current collectors on both sides, and then electrochemical impedance analysis was performed. When conducting electrochemical impedance analysis, an electrochemical cell is manufactured so that a positive electrode active material layer is placed between two positive electrode current collectors, so that ionic conductivity and electronic conductivity can be analyzed (Journal of power sources, 2016, 316, 215-223). For example, if a Nyquist plot is drawn using the impedance measured by applying an AC impedance of 10 MHz to 1 mHz frequency to the electrochemical cell, multiple curves similar to a semicircle shape may be drawn continuously, for example, three large and small curves may be drawn continuously from a high-frequency region to a low-frequency region, and by fitting the low-frequency region to an equivalent circuit, the resistance values ​​R1 and R2 may be used to calculate the electronic resistance RE = R1 + R2 and the ionic resistance RI = (R1 + R2) * R1 / R2. Each resistance may be converted to the conductivity of the electrode by considering the thickness and area of ​​the electrode. At this time, the equivalent circuit may be an R1+Q2 / R2 model (R: Resister, Q: Constant Phase Element).

[0104] As a result, it was confirmed that the positive electrode of Example 1 had higher electrical conductivity and ionic conductivity than the positive electrode of Comparative Example 1, as shown in Table 2 below.

[0105] [Table 2]

[0106]

[0107] (At this time, each of Example 1 and Comparative Example 1 was measured three times, and the average value was used as the result value in Table 2 above.)

[0108] Evaluation Example 3. Bipolar tensile strength evaluation

[0109] The anodes of Example 1 and Comparative Example 1 were punched according to the ASTM D638 mold to produce dog bone-shaped tensile specimens. The effective gauge length and effective width of the tensile specimens were 9.53 mm and 3.18 mm, respectively. The tensile specimens were mounted on a UTM device (LS1, Lloyd Instruments) and stretched at a rate of 5 mm / min until the point of break, and the tensile strength calculated after break was recorded.

[0110] As a result, it was confirmed that the positive electrode of Example 1 showed a tensile strength that was approximately 9% higher than that of Comparative Example 1, even though it contained a smaller amount of binder, as shown in Table 3 below.

[0111] [Table 3]

[0112]

[0113] Example 2.

[0114] An all-solid-state battery was manufactured by sequentially stacking a negative electrode current collector (Cu foil), lithium metal, a sulfide-based solid electrolyte membrane composed of Li6PS5Cl, and the positive electrode and positive electrode current collector (Al foil) of Example 1. Here, each part of the positive electrode current collector and the negative electrode current collector was protruded outside the pouch so that the battery could maintain a vacuum, and these protrusions were used as positive and negative electrode terminals. In addition, this all-solid-state battery was subjected to a hydrostatic treatment at 500 MPa for 30 minutes. By performing this hydrostatic treatment, the characteristics as a battery are greatly improved.

[0115] Comparative Example 2.

[0116] An all-solid-state battery was manufactured in the same manner as Example 2, except that the positive electrode of Comparative Example 1 was introduced as the positive electrode.

[0117] Evaluation Example 3. Monocell Performance Evaluation

[0118] The all-solid-state batteries (pouch-type monocells) of Example 2 and Comparative Example 2 were operated under the following charge-discharge conditions at an operating voltage range of 4.25 V to 3.0 V and an operating temperature of 60°C, and the discharge capacity retention rates at 0.33 C, 0.5 C, and 1.0 C were evaluated compared to the second discharge capacity at 0.1 C, and the results are shown in Table 4 below.

[0119] Charging conditions: 0.1C, 4.25V CC / CV, 0.05C cut-off

[0120] Discharge conditions: 0.1C 2 times, 0.33C, 0.5C or 1.0C, 3.0V, CC

[0121] [Table 4]

[0122]

[0123] As a result, it was confirmed that the discharge capacity retention rate of Example 2 was higher than that of Comparative Example 2 at a high C-rate. This is because, in the case of Example 2, the binding between the positive electrode components is strong, securing an electron movement path and a lithium ion path, thereby effectively controlling the decrease in discharge capacity even at a high C-rate.

Claims

1. An anode including a positive electrode active material layer, The above cathode active material layer includes a cathode active material, a sulfide-based solid electrolyte, a conductive composite material, and a fiber-forming binder. The above-mentioned conductive composite material comprises a core portion including a carbon-based conductive material and a coating portion positioned on at least a portion of the core portion and including polymer nanoparticles, A cathode, characterized in that the above polymer nanoparticles are a copolymer of polyvinylidene fluoride (PVDF) and a comonomer, and the comonomer is at least one selected from the group consisting of hexafluoropropylene (HFP), chlorotrifluoroethylene (CTFE), hexafluoroacetone (HFA), 1-hydropentafluoropropylene (HPFP), tetrafluoroethylene (TFE), and trifluoroethylene (TrFE).

2. An anode according to claim 1, characterized in that the fibrous binder is polytetrafluoroethylene (PTFE).

3. A positive electrode characterized in that, in claim 1, the positive electrode active material layer contains 1.2 parts by weight or less of a fiberizing binder per 100 parts by weight.

4. A positive electrode according to claim 1, characterized in that the weight ratio of polymer nanoparticles to the challenging composite material is 5 to 50 wt%.

5. In the first paragraph, the polymer nanoparticle is a positive electrode characterized in that the polymerization ratio between polyvinylidene fluoride (PVDF) and the comonomer is in the range of 99:1 to 75:

25.

6. An anode according to claim 1, characterized in that the carbon-based conductive material is at least one selected from the group consisting of graphite, carbon black, and carbon fiber.

7. In the first paragraph, the BET surface area of ​​the carbon-based conductive material is 10 m 2 A cathode characterized by having a value of / g or less.

8. An anode according to claim 1, characterized in that the average length of the carbon-based conductive material is 5 to 20 ㎛.

9. In the first paragraph, the sulfide-based solid electrolyte is Li 2 SP 2 S 5 -Li 2 O,Li 2 SP 2 S 5 -Li 2 O-LiI,Li 2 S-LiBr-LiI-P 2 S 5 ,Li 2 S-SiS 2 ,Li 2 S-SiS 2 -LiI,Li 2 S-SiS 2 -LiBr,Li 2 S-SiS 2 -LiCl,Li 2 S-SiS 2 -B 2 S 3 -LiI,Li 2 S-SiS 2 -Li 3 PO 4 ,Li 2 S-SiS 2 -Li p MO q (p,q are positive numbers, M is one of P, Si, Ge, B, Al, Ga, and In), Li 2 S-SiS 2 -P 2 S 5 -LiI,Li 2 SP 2 S 5 ,Li 2 SP 2 S 5 -LiX (X is a halogen element), Li 2 SB 2 S 3 ,Li 2 SP 2 S 5 -Z m S n (m,n are positive numbers), Z is one of Ge, Zn or Ga, L i2 S-GeS 2 ,Li 7-x PS 6-x Cl x (0≤x≤2), Li 7-x PS 6-x Br x (0≤x≤2) and Li 7-x PS 6-x I x An anode characterized by having at least one selected from the group comprising (0≤x≤2).

10. An anode according to claim 1, characterized in that it is a dry anode.

11. An all-solid-state battery comprising a positive electrode, a solid electrolyte layer, and a negative electrode, The above positive electrode includes a positive electrode active material layer, The above cathode active material layer includes a cathode active material, a sulfide-based solid electrolyte, a conductive composite material, and a fiber-forming binder. The above-mentioned conductive composite material comprises a core portion including a carbon-based conductive material and a coating portion positioned on at least a portion of the core portion and including polymer nanoparticles, An all-solid-state battery, characterized in that the polymer nanoparticles are a copolymer of polyvinylidene fluoride (PVDF) and a comonomer, and the comonomer is at least one selected from the group consisting of hexafluoropropylene (HFP), chlorotrifluoroethylene (CTFE), hexafluoroacetone (HFA), 1-hydropentafluoropropylene (HPFP), tetrafluoroethylene (TFE), and trifluoroethylene (TrFE).

12. An all-solid-state battery according to claim 11, characterized in that the solid electrolyte layer comprises at least one selected from the group consisting of a sulfide-based solid electrolyte, an oxide-based solid electrolyte, and a halide-based solid electrolyte.

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