Positive electrode and all-solid-state battery including it

Abstract

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

Description

[Technical Field]

[0001] This application claims priority under Korean Patent Application No. 2023-0162162 dated November 21, 2023, and all contents disclosed in the said Korean Patent Application are included as part of this specification. The present invention relates to a positive electrode and an all-solid-state battery including the same. [Background technology]

[0002] Customer demand for secondary batteries with high energy density and high stability is rapidly increasing. To meet this demand, technological development is progressing for various all-solid-state battery electrodes, and among these, sulfide-based all-solid-state batteries, which have high ionic conductivity and can realize theoretically high energy density, are attracting particular attention.

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

[0004] During this process, repeated charging and discharging of the all-solid-state battery causes volume expansion and contraction of the positive electrode active material, leading to the problem of continuous breakdown of the contact interface between the positive electrode active material and the sulfide-based solid electrolyte. To solve this problem, it is necessary to introduce a polymer binder with excellent bonding properties while suppressing side reactions of the sulfide-based solid electrolyte. However, since such polymer binders have low electrical conductivity, it is necessary to continuously reduce their content within the electrode to improve performance. [Overview of the Initiative] [Problems that the invention aims to solve]

[0005] The present invention aims to solve the aforementioned problems and to provide a positive electrode and an all-solid-state battery containing the same that are excellent in terms of ion / electrical conductivity and charge / discharge performance, as well as excellent in mechanical properties such as tensile strength. [Means for solving the problem]

[0006] A first aspect of the present invention relates to a positive electrode comprising a positive electrode active material layer, wherein the positive electrode active material layer comprises a positive electrode active material, a sulfide-based solid electrolyte, a conductive material composite, and a fibrous binder, and the conductive material composite comprises a core portion comprising a carbon-based conductive material and a coating portion located on at least a part of the core portion comprising polymer nanoparticles, wherein the polymer nanoparticles are a copolymer of polyvinylidene fluoride (PVDF) and a comonomer, and the comonomer is one or more 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 fibrous binder may be characterized by being polytetrafluoroethylene (PTFE).

[0008] In one embodiment, the fibrous binder may be contained in an amount of 1.2 parts by weight or less per 100 parts by weight of the positive electrode active material layer.

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

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

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

[0012] In one example, the BET specific surface area of ​​the carbon-based conductive material is 10 m². 2It may be characterized by being below / g.

[0013] In one embodiment, it may be characterized in that the average length of the carbon-based conductive material is 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 may be characterized by being one or more selected from the group including (0 ≦ x ≦ 2).

[0015] In one embodiment, the positive electrode of the present invention may be characterized by being a dry positive electrode.

[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 material composite, and a fibrous binder, the conductive material composite comprises a core portion comprising a carbon-based conductive material and a coating portion located on at least a part 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 one or more 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 containing one or more selected from the group including sulfide-based solid electrolytes, oxide-based solid electrolytes, and halide-based solid electrolytes. [Effects of the Invention]

[0018] According to the present invention, it is possible to provide a positive electrode and an all-solid-state battery containing the same that are excellent in terms of ion / electrical conductivity and charge / discharge performance, as well as excellent in mechanical properties such as tensile strength. [Best Mode for Carrying Out the Invention]

[0019] The terms and words used in this specification and in the claims should not be construed to be limited to their ordinary or dictionary meanings, but rather to be construed in a sense and concept consistent with the technical idea of ​​the present invention, based on the principle that inventors can appropriately define the concepts of terms in order to best describe their inventions.

[0020] Therefore, the configurations of the embodiments described herein represent only one of the most preferred embodiments of the present invention and do not represent the entire technical concept of the invention. It should be understood that, at the time of filing, there may be a variety of equivalents and modifications that can be substituted for these.

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

[0022] In this specification, when a part is said to "contain" a component, this means, unless otherwise stated, that it may contain other components rather than excluding them. For example, a composition containing compound A may contain other compounds other than A. However, the term "contains" also encompasses, in its particular embodiment, the more restrictive meanings of "essentially / essentially composed of" and "composed of," for example, a "composition containing compound A" may also be (essentially / essentially) composed of compound A.

[0023] In this regard, as described herein, terms such as “equipped with” or “possess” are intended to specify the presence of implemented features, figures, stages, components, or combinations thereof, and should be understood not to preemptively exclude the possibility of the presence or addition of one or more different features, figures, stages, components, or combinations thereof.

[0024] In this specification, when any layer is said to be 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 there are other layers or materials between the two layers.

[0025] Where, in this specification, a quantity, concentration, or other value or parameter is given by listing a range, preferred range, preferred upper limit, and preferred lower limit, it should be understood that this specifically discloses all ranges that can be formed by any pair of any upper range limits or preferred values ​​and any lower range limits or preferred values, regardless of whether the range is disclosed separately. Where, in this specification, a range of numerical values ​​is referred to, unless otherwise stated, and unless there are limiting terms such as greater than or less than, the range is intended to include its endpoint and all integers and fractions within that range. The scope of the present invention is intended not to be limited to specific values ​​referred to when defining a range.

[0026] In this specification, if the measurement temperature affects any physical property, unless otherwise specified, the property is measured at room temperature. Room temperature refers to the natural temperature without heating or deheating, and may mean, for example, any temperature within the range of approximately 10°C to 30°C, or approximately 23°C or 25°C. Unless otherwise specified, the unit of temperature in this specification is °C.

[0027] Furthermore, in the case of any physical properties mentioned herein where the measurement pressure affects the property, unless otherwise specified, the property is measured at normal pressure, i.e., atmospheric pressure (approximately 1 atmosphere).

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

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

[0030] The first aspect of this invention relates to the positive electrode.

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

[0032] The fibrous binder may be, for example, polytetrafluoroethylene (PTFE). The PTFE has two phase transition temperatures at 19°C and 30°C, and when stress is applied between polymer powders at temperatures above 19°C, fibrous properties are exhibited, allowing for uniform bonding of other electrode elements. Because PTFE has these inherent fibrous properties, it can bond electrode materials into a uniform form in a solvent-free system. In this specification, "solvent-free system" may mean, for example, a system in which materials such as active material, electrolyte, conductive material and / or binder are mixed without solvent during the manufacture of an electrode slurry.

[0033] The positive electrode of the present invention, by including the above-mentioned fibrous binder in the positive electrode active material layer, possesses advantages such as the high ionic conductivity and soft physical properties of sulfide-based solid electrolytes, allowing for processes at room temperature, while also being able to control side reactions such as hydrogen sulfide gas generation due to the high moisture sensitivity of sulfide-based solid electrolytes.

[0034] The positive electrode of the present invention may be characterized by containing, for example, 1.2 parts by weight or less of the fibrous binder per 100 parts by weight of the positive electrode active material layer. In other examples, the positive electrode of the present invention may be characterized by containing 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 per 100 parts by weight of the positive electrode active material layer, 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. As the binder content in the positive electrode active material layer increases, the bonding characteristics improve, but the conductivity decreases, which can result in a decrease in battery performance. That is, it is known that the tensile strength and conductivity of the positive electrode active material layer are in a trade-off relationship with each other. However, the present invention has confirmed that by introducing conductive composite materials, etc., it is possible to have excellent tensile strength and conductivity while reducing the binder content in the positive electrode active material layer.

[0035] The conductive composite material may include, for example, a core portion containing a carbon-based conductive material and a coating portion located on at least a portion of the core portion and containing polymer nanoparticles. In this specification, "the coating portion is located 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 core portion surface, or 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 this specification, "the coating portion covers the core portion surface" may mean that the coating portion is formed on the core portion to a thickness of at least 100 nm or more. The core portion may contain a carbon-based conductive material in an amount of, for example, 70% or more by weight, 80% or more by weight, 90% or more by weight, 95% or more by weight, or 100% by weight. The coating portion may contain polymer nanoparticles in an amount of, for example, 70% or more by weight, 80% or more by weight, 90% or more by weight, 95% or more by weight, or 100% by weight.

[0036] The polymer nanoparticles are, for example, a copolymer of polyvinylidene fluoride (PVDF) and a comonomer, and the comonomer may be one or more 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 can have excellent conductivity by including such a copolymer of polyvinylidene fluoride (PVDF) and a comonomer in the positive electrode active material layer. Furthermore, while the comonomer can be any one or more of the examples described above without limitation, hexafluoropropylene (HFP) may be preferred in terms of increasing the elongation rate of the positive electrode active material layer and thereby ensuring ease of processing.

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

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

[0039] The carbon-based conductive material may be characterized by being one or more selected from the group consisting of, for example, graphite and carbon black such as acetylene black, Ketjen black, channel black, furnace black, lamp black, and thermal black, or carbon fibers. In some cases, the carbon-based conductive material is preferably carbon fiber because it minimizes interface formation with sulfide-based solid electrolytes and controls the decomposition phenomenon of the electrolyte during electrochemical reactions.

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

[0041] The average length of the carbon-based conductive material may be, for example, 5 to 20 μm. In other examples, the average length of the carbon-based conductive material may be 7 μm or more, 9 μm or more, or 11 μm or more, or 19 μm or less, 18 μm or less, 17 μm or less, 16 μm or less, 15 μm or less, 14 μm or less, or 13 μm or less. By controlling the average length of the carbon-based conductive material contained in the core of the conductive material composite as described above, it is possible to improve electrical conductivity by ensuring sufficient conductive paths between positive electrode active materials within the positive electrode active material layer, while also improving dispersibility.

[0042] The positive electrode of the present invention may be characterized, for example, by having a weight ratio of conductive composite material to the fibrous binder of 0.01 to 100. In other examples, the positive electrode of the present invention may have a weight ratio of conductive composite material to the fibrous binder of 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 aforementioned sulfide-based solid electrolytes are, 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, and Li2S-SiS2-Li p MO q (p and 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 and n are positive numbers), Z is one of Ge, Zn, or Ga, Li2S-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 one or more selected from the group that includes (0≦x≦2).

[0044] Sulfide-based solid electrolytes can be manufactured by processing starting materials such as Li2S and P2S5 using methods such as melt-quenching or mechanical milling. Furthermore, heat treatment can be performed after such processing. Solid electrolytes can be amorphous, crystalline, or a mixture thereof. The sulfide-based solid electrolyte in this invention may, for example, contain sulfur (S), phosphorus (P), and lithium (Li) as at least one constituent element of the aforementioned sulfide-based solid electrolyte material.

[0045] The aforementioned 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 x The compound may be an argyrodite-type compound containing at least one selected from (0 ≤ x ≤ 2). In particular, sulfide-based solid electrolytes may be argyrodite-type compounds containing one or more selected from Li6PS5Cl, Li6PS5Br, and Li6PS5I.

[0046] The density of the azirodite-type solid electrolyte may be, for example, 1.5 to 2.5 g / cc. Having a density of 1.5 g / cc or higher for the azirodite-type solid electrolyte reduces the internal resistance of the all-solid-state secondary battery, effectively suppressing penetration of the solid electrolyte by Li.

[0047] The elastic modulus of the 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, by having a weight ratio of sulfide-based solid electrolyte to the conductive composite material of 0.01 to 100. In other examples, the positive electrode of the present invention may have a weight ratio of sulfide-based solid electrolyte to the conductive composite material of 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 positive electrode of the present invention may be characterized, for example, by being a dry positive electrode. In this specification, "dry positive electrode" is a positive electrode manufactured without the use of a solvent, and the dry positive electrode may contain a solvent of 1% by weight or less, 0.1% by weight or less, or 0.001% by weight or less, or may contain no solvent at all.

[0050] The positive electrode of the invention may further include, for example, other conductive materials other than the conductive composite material in the positive electrode active material layer. The other conductive materials are different from the conductive composite material and may differ in that they do not include the above-mentioned coating portion or the coating portion does not include polymer nanoparticles having the above-mentioned characteristics. The other conductive materials may be, but are not limited to, graphite, carbon black, acetylene black, Ketjen black, carbon fibers, carbon nanotubes, or metal powders, and 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 hinder the objective of the present invention.

[0051] The positive electrode active material reversibly intercalates and deintercalates lithium ions. The positive electrode active material 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 manganese oxide, lithium iron phosphate, nickel sulfide, copper sulfide, lithium sulfide, iron oxide, or vanadium oxide, but any material used as a positive electrode active material in the art is acceptable. The positive electrode active materials may be used individually or in combination of two or more.

[0052] The lithium transition metal oxide is, for example, Li a A 1-b B b D2 (wherein the above formula, 0.90 ≤ a ≤ 1 and 0 ≤ b ≤ 0.5) and Li a Ni 1-b-c Co 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) and 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, and 0 ≤ α ≤ 2) and 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, and 0 < α ≤ 2) and 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), and LiE 2-b B b O 4-c D c (In the above formula, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05), and 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), and Li a CoG b O2 (In the above formula, 0.90 ≤ a ≤ 1, 0.001 ≤ b ≤ 0.1), and Li a MnG b O2 (In the above formula, 0.90 ≤ a ≤ 1, 0.001 ≤ b ≤ 0.1), and Li a Mn2G<� b O4 (In the above formula, 0.90 ≤ a ≤ 1, 0.001 ≤ b ≤ 0.1), and 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), and Li a Ni 1-b-c Mn b B c O 2-α F2 (In the above formula, 0.90 ≤ a ≤ I, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, 0 < α < 2), and 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), and 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), and Li a NiG b It should be noted that there may be some incorrect tags in the original text, such as <� b which should probably be b . This translation is based on the best understanding of the provided content with the given tags.O2 (where 0.90 ≤ a ≤ 1 and 0.001 ≤ b ≤ 0.1 in the above formula), QO2, QS2, LiQS2, V2O5, LiV2O5, LiIO2, LiNiVO4, Li (3-f) J2(PO4)3(0≦f≦2) and Li (3-f) The compound may be represented by either the chemical formula Fe2(PO4)3 (0≦f≦2) or LiFePO4. In such a compound, A may be Ni, Co, Mn, or a combination thereof; B may be Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, rare earth elements, or a combination thereof; D may be O, F, S, P, or a combination thereof; E may be Co, Mn, or a combination thereof; F may be F, S, P, or a combination thereof; G may be Al, Cr, Mn, Fe, Mg, La, Ce, Sr, V, or a combination thereof; Q may be Ti, Mo, Mn, or a combination thereof; I may be Cr, V, Fe, Sc, Y, or a combination thereof; and J may be V, Cr, Mn, Co, Ni, Cu, or a combination thereof. As the positive electrode active material, a compound with a coating layer attached to its surface may be used, or a mixture of the above-mentioned compound and the compound with the coating layer attached may be used. The coating layer added to the surface of such a compound may contain, for example, a lithium-ion conductive oxide. The lithium-ion conductive oxide may be, for example, LiNbO3, Li4Ti5O 12 Examples include, but are not limited to, Li3PO4. The compounds constituting such a coating layer may be amorphous or crystalline. The method for forming the coating layer may include, for example, spray coating or immersion coating, but can be selected without limitation as long as it does not adversely affect the physical properties of the positive electrode active material.

[0053] When the positive electrode active material includes nickel (Ni) as a ternary lithium transition metal oxide such as NCA or NCM, it is possible to increase the capacity density of the all-solid-state battery and reduce metal leaching from the positive electrode active material in the charged state. This can improve the cycle characteristics of the all-solid-state battery in the charged state.

[0054] The shape of the positive electrode active material may be, for example, a perfect sphere, an ellipsoid, or some other particle shape. The particle size of the positive electrode active material is not particularly limited and should be within a range applicable to the positive electrode active material of conventional all-solid-state secondary batteries. The content of the positive electrode active material in the positive electrode is also not particularly limited and should be within a range applicable to the positive electrode of conventional all-solid-state secondary batteries.

[0055] The positive electrode active material layer may further contain additives such as fillers, coating agents, dispersants, and ion-conducting aids, and these additives can be used without limitation as long as they are known materials commonly used in electrodes for 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 usable as a current collector for all-solid-state batteries 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, for example, have a ratio of tensile strength (MPa) to the content (weight%) of fibrous binder contained in the positive electrode active material layer of 0.1 MPa / weight% or more. The tensile strength may be measured by the method described in the evaluation example later. In other examples, the positive electrode of the present invention may have a ratio of tensile strength to the content of fibrous binder contained in the positive electrode active material layer of 0.11 MPa / weight% or more, 0.12 MPa / weight% or more, or 0.13 MPa / weight% or more, and there is no particular upper limit, but it may be around 1 MPa / weight% or less or 0.5 MPa / weight% or less.

[0059] The positive electrode of the present invention, for example, has an electrical conductivity (S / cm) ratio of 3.5.E to the content (weight %) of the fibrous binder contained in the positive electrode active material layer. ー05 The electrical conductivity may be (S / cm) / weight% or greater. The aforementioned electrical conductivity may be measured by the method described in the evaluation example later. In other examples, the positive electrode of the present invention has an electrical conductivity (S / cm) ratio of fibrous binder content (weight%) 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% may be greater than or equal to 20.E -05 (S / cm) / weight% or less, 15.E -05 (S / cm) / weight% or less or 10.E -05 (S / cm) / weight % may be less than or equal to

[0060] The positive electrode of the present invention, for example, has a ratio of ionic conductivity (S / cm) to the content (weight %) of the fibrous binder contained in the positive electrode active material layer of 2.5.E. ー05 The ionic conductivity may be (S / cm) / weight% or greater. The ionic conductivity may be measured by the method described in the evaluation example below. In other examples, the positive electrode of the present invention has a ratio of ionic conductivity (S / cm) to content (weight%) of fibrous binder contained 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% may be greater than or equal to 20.E -05 (S / cm) / weight% or less, 15.E -05 (S / cm) / weight% or less or 10.E-05 (S / cm) / weight % may be less than or equal to

[0061] A second aspect of the present invention relates to all-solid-state batteries.

[0062] Unless otherwise specified, matters relating to the first aspect of the present invention may be similarly applied to matters relating to the second aspect.

[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 material composite, and a fibrous binder, the conductive material composite comprises a core portion comprising a carbon-based conductive material and a coating portion located on at least a part 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 one or more selected from the group consisting of hexafluoropropylene (HFP), chlorotrifluoroethylene (CTFE), hexafluoroacetone (HFA), 1-hydropentafluoropropylene (HPFP), tetrafluoroethylene (TFE), and trifluoroethylene (TrFE).

[0064] The solid electrolyte layer may include, for example, a sulfide-based solid electrolyte, an oxide-based solid electrolyte, or a halide-based solid electrolyte, but is not limited thereto; any such electrolyte commonly used in all-solid-state batteries is acceptable. The sulfide-based solid electrolyte included in the solid electrolyte layer may be, for example, at least one of the examples of sulfide-based solid electrolytes included in the 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, one or more of garnet-type solid electrolytes, nasicon-type solid electrolytes, lisicon-type solid electrolytes, or perovskite-type solid electrolytes. Specifically, the oxide-based solid electrolyte may be Li7La3Zr2O12 , those in which elements such as Al, Y, Ga, Ta, Nb, etc. are doped in place of Li in the above Li7La3Zr2O 12 , or those in which Ga 12 is multi-doped at the Li and La, Zr element positions in the above Li7La3Zr2O +3 -Sc +3 etc., or those in which substances such as Al2CO3, Ge, ZnO, etc. are coated on the surfaces of these are used, or 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) or those in which atoms with an oxidation number of +3 such as Y, La, Sc, etc. are doped in place of the above Al or those doped with atoms with an oxidation number of +2 such as Sr, Mg, Ca, etc. are used, or xLi3AO 4- (1 - x)Li4BO4 (A: P, As, V, etc., B: Si, Ge, Ti, etc.) or those with Li3BO3, etc. added thereto, or, Li 3x La 2 / 3-x □ 1 / 3-2x TiO3 (LLTO, 0 < x < 0.16, □ is a vacancy), La 0.57-2x / 3 Sr x Li 0.3 TiO3, etc. can be used, but are not limited thereto. As the above halide-based solid electrolyte, Li2ZrCl6, Li 2+x Zr 1-x M x Cl6 (M = Fe, Cr, V), and Na2ZrCl6, etc. can be used, but are not limited thereto.

[0065] The shape of the solid electrolyte may be, for example, a particle shape. The average particle size (D50) of the solid electrolyte may be, for example, in the range of 0.5 to 4 μm. The solid electrolyte may be used alone or in combination of two or more types. If the solid electrolyte layer contains two or more types of solid electrolytes, the two or more types of solid electrolytes may be mixed in one layer, or separate layers containing each solid electrolyte may be formed to create a multilayer structure, or the solid electrolytes may be mixed and separate layers may be formed with the same or different mixing ratios to create a multilayer structure. In this specification, the average particle size (D50) may mean the diameter at which the cumulative volume of the particles, when the particle diameters measured by laser diffraction scattering particle size distribution measurement are arranged in ascending order, equal to half (50%) of the total volume.

[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, polyvinyl alcohol, carboxymethylcellulose, hydroxypropylcellulose, diacetylcellulose, polyvinylidene fluoride, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, polymers containing ethylene oxide, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene, fluoride, polyethylene, polypropylene, styrene-butadiene rubber, acrylated styrene-butadiene rubber, epoxy resin, nylon, or a combination thereof. The aqueous binder may be, for example, styrene-butadiene rubber, carboxymethylcellulose, or a combination thereof. The organic binder may be, for example, polytetrafluoroethylene, polyvinylidene fluoride, or a combination thereof, but is not limited thereto; known binders may be used without limitation as long as they do not hinder the objective of the present invention. The solid electrolyte layer may contain, for example, 5% by weight or less of a binder.

[0067] The thickness of the solid electrolyte layer is not particularly limited, but is usually in the range of 0.1 μm to 1 mm.

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

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

[0070] The negative electrode active material is, for example, lithium, lithium alloy, carbon, silicon, silicon alloy, or Li4Ti5O 12 (LTO), etc., or the aforementioned lithium, lithium alloy, carbon, silicon, silicon alloy or Li4Ti5O 12 It can be selected from alloys of (LTO) and at least one metal selected from the group consisting of Sn, Ge, and Al.

[0071] The aforementioned solid electrolyte, conductive material, and / or binder may be one of the types included in the positive electrode or solid electrolyte layer described above, but is not limited to these; any solid electrolyte, conductive material, and / or binder used in the art is acceptable. 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 negative electrode active material layer may further include, for example, other additives. These additives can be any known material commonly used in electrodes for all-solid-state batteries, without limitation.

[0073] The negative electrode may further include a negative electrode current collector. The negative electrode current collector can be a known metal usable as a current collector in all-solid-state batteries. For example, the negative electrode current collector may be made of a material that does not form alloys or compounds with lithium. The negative electrode current collector may be selected from the group consisting of, for example, 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 art can be used as long as it does not hinder the purpose of the present invention. The negative electrode current collector may be composed of one of the above-mentioned metals, or of an alloy or coating material of two or more metals. The negative electrode current collector may be, for example, in the form of a plate, mesh, or foil, but is not limited to these.

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

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

[0076] In this specification, "negative electrode coating layer" refers to a coating layer formed between the negative electrode current collector and the solid electrolyte layer, or on one surface of the solid electrolyte layer, when there is no negative electrode current collector, after lithium is absorbed into the negative electrode coating layer during charging and exceeds the charging capacity of the negative electrode coating layer. In an all-solid-state battery, lithium is deposited between the negative electrode current collector and the negative electrode coating layer, or on one surface of the solid electrolyte layer when there is no negative electrode current collector, after exceeding the charging capacity of the negative electrode coating layer. During discharge, the lithium in the negative electrode coating layer and the lithium metal layer are ionized and move to the positive electrode side. The "negative electrode coating layer" refers to a coating layer formed between the negative electrode current collector and the solid electrolyte layer, or on one surface of the solid electrolyte layer when there is no negative electrode current collector, and may differ in composition and operating mechanism from the aforementioned negative electrode active material layer. The negative electrode coating layer can cover the lithium metal layer during the charging process and act as a protective layer for the lithium metal layer, suppressing the deposition and growth of lithium dendrites, thereby suppressing short circuits and capacity degradation in the all-solid-state battery and potentially improving performance.

[0077] The aforementioned electrode-free coating layer may include, for example, amorphous carbon. The amorphous carbon contained in the electrode-free coating layer may be, for example, one or more selected independently from the group consisting of carbon black, acetylene black, furnace black, Ketjen black, and graphene, but is not limited to these, and any amorphous carbon that can be used in an electrode-free all-solid-state battery may be used without limitation.

[0078] The non-negative electrode 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, one or more metals, quasimetallic elements, or combinations 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 the maximum particle size, minimum particle size, or 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 non-negative electrode coating layer may further include, for example, a binder. The binder may be selected from, or not limited to, the binders mentioned above that may be included in the positive electrode active material layer, solid electrolyte layer, negative electrode active material layer, etc., and any known binder may be used without limitation.

[0081] The negative electrode may optionally include a negative electrode current collector on one surface of the non-negative electrode coating layer, and the aforementioned negative electrode current collector can be used without limitation.

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

[0083] The thickness of the thin film may be, for example, 1 to 800 nm, 10 to 700 nm, 50 to 600 nm, or 100 to 500 nm. The thin film may be formed by, for example, vacuum deposition, sputtering, plating, etc., but is not limited to these methods; any method capable of forming a thin film in the art is acceptable.

[0084] If the non-negative electrode coating layer is included, the all-solid-state battery may further include, by charging, a metal and / or metal layer containing lithium or a lithium alloy between the negative electrode current collector and the non-negative electrode coating layer, on the side of the non-negative electrode coating layer opposite to the solid electrolyte layer, and / or within the non-negative electrode coating layer. The lithium alloy may be, for example, Li-Al alloy, Li-Sn alloy, Li-In alloy, Li-Ag alloy, Li-Au alloy, Li-Zn alloy, Li-Ge alloy, Li-Si alloy, or any other alloy used as a lithium alloy in the art. The metal or metal layer between the negative electrode current collector and the non-negative electrode coating layer, and / or within the non-negative electrode coating layer may consist of one of such alloys or lithium, or several types of alloys.

[0085] The thickness of the metal layer containing lithium or a lithium alloy may be, for example, within the 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 in order for the metal layer to function as a lithium storage vessel and to improve cycle characteristics.

[0086] The metal layer may be formed, for example, by charging after the assembly of the all-solid-state battery, either between the negative electrode current collector and the non-negative electrode coating layer, or on the side of the non-negative electrode coating layer opposite to the solid electrolyte layer. When the metal layer is formed by charging after the assembly of the all-solid-state battery, the region between the negative electrode current collector and the non-negative electrode coating layer, or on the side of the non-negative electrode coating layer opposite to the solid electrolyte layer, may contain lithium, for example, lithium-free (Li) in the initial state or after discharge of the all-solid-state battery. - It could be a free area. [Modes for carrying out the invention]

[0087] In the following, the present invention will be described in detail with reference to examples in order to specifically illustrate the disclosures of the present invention as described above and the intended functions and effects of the present invention. However, the examples may be modified into several different forms, and the scope of this specification should not be construed as being limited to these examples alone. It should be emphasized that the examples are provided to specifically illustrate the present invention to those skilled in the art.

[0088] Manufacturing example.

[0089] After dispersing PVDF-HFP in an organic solvent at a fixed weight ratio, carbon fibers (BET10m) are coated using a spray coater. 2 The material is coated on a surface with a density of 12 μm or less (average fibrous length). As a result, PVDF-HFP nanoparticles are coated on the carbon fiber surface, 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 can be obtained.

[0090] Example 1.

[0091] A powder mixture was prepared using a weight ratio of 78:19.5:1.5:1 for the positive electrode active material, sulfide-based solid electrolyte, conductive material, and binder. Specifically, the positive electrode active material and sulfide-based solid electrolyte were quantified in powder form, then mixed for 15 minutes in a dry room environment using agate induction. After quantifying the conductive material and adding it to the mixture, it was mixed for another 15 minutes. Then the binder was quantified and added to the mixture, and mixed further to obtain a mixed powder. Fiber formation was then advanced on the mixed powder using induction, and calendering was carried out with rollers to achieve a yield of 6 mAh / cm². 2 A cathode containing a positive electrode active material layer of a certain level was manufactured.

[0092] In this case, LiNi is used as the positive electrode active material. 0.8 Co 0.1 Mn 0.1 O2(NCM), Li6PS5Cl, an azirodite-type crystalline sulfide-based solid electrolyte, a conductive composite material manufactured according to the above manufacturing example as the conductive material, and PTFE(601X, Chemours) as the binder, wherein the conductive composite material contains PVDF. - The total weight of HFP nanoparticles and 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, instead of the conductive composite material used in the manufacturing example, carbon fiber (BET10m 2 Using a material with a density of 6 mAh / cm² or less (average fibrous length of 12 μm), and employing the same method as the example except that the weight ratio of positive electrode active material: sulfide-based solid electrolyte: conductive material: binder was 78:19.5:1.2:1.3, the output was 6 mAh / cm². 2 A cathode containing a positive electrode active material layer of a certain level was manufactured.

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

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

[0097] As a result, it was confirmed that the mixed powder of Example 1 exhibited superior flow stability compared to the mixed powder of Comparative Example 1, as shown in Table 1 below. This is presumed 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] (At this time, measurements were taken twice for each example and comparative example, and the average value was taken as the result value in Table 1 above.)

[0100] Here, the confined stability index (%) is the ratio of flow energy measured in the direction of entering the cup when a blade attached to a rheometer rotates at a constant speed while moving up and down in a cup containing powder. This represents the ratio of the energy value at the end of the rotation to the energy value at the beginning of the rotation. On the other hand, the unconfined stability index (%) is the ratio of flow energy measured in the direction of entering the cup when a blade attached to a rheometer rotates at a constant speed while moving up and down in a cup containing powder. Similarly, this represents the ratio of the energy value at the end of the rotation to the energy value at the beginning of the rotation.

[0101] Evaluation Example 2. Evaluation of positive electrode conductivity

[0102] The positive electrodes of Example 1 and Comparative Example 1 were punched out to a size of 18 mm * 18 mm, and Al foil was placed on both sides as positive electrode current collectors. After packaging, electrochemical impedance analysis was performed. For electrochemical impedance analysis, an electrochemical cell can be manufactured so that a positive electrode active material layer is placed between two positive electrode current collectors, and the ionic conductivity and electronic conductivity can be analyzed (Journal of Power Sources, 2016, 316, 215-223). For example, when an AC impedance of 10 MHz to 1 mHz is applied to the electrochemical cell and the measured impedance is shown in a Nyquist plot, multiple similar curves in a semicircular shape can be shown consecutively. For example, three curves of varying sizes are shown consecutively from the high-frequency region to the low-frequency region. By fitting the low-frequency region to an equivalent circuit, the electronic resistance RE = R1 + R2 and the ionic resistance RI = (R1 + R2) * R1 / R2 can be calculated using the obtained resistance values ​​R1 and R2. Each resistance can be converted to the conductivity of the electrodes, taking into account the thickness and area of ​​the electrodes. In this case, the equivalent circuit can be the R1 + Q2 / R2 model (R: Resister, Q: Constant Phase Element).

[0103] As a result, it was confirmed that the positive electrode of Example 1 had higher electrical conductivity and ionic conductivity compared to the positive electrode of Comparative Example 1, as shown in Table 2 below.

[0104] [Table 2]

[0105] (At this time, measurements were taken three times for each of Example 1 and Comparative Example 1, and the average value was taken as the result value in Table 2 above.)

[0106] Evaluation Example 3. Evaluation of Positive Electrode Tensile Strength

[0107] The positive electrodes of Example 1 and Comparative Example 1 were punched out according to the ASTM D638 die to produce dogbone-shaped tensile test specimens. The effective gauge length of these tensile test specimens was 9.53 mm and the effective width was 3.18 mm. After mounting the tensile test specimens in a UTM (LS1, Lloyd Instruments) system, the experiment was conducted while pulling at a speed of 5 mm / min until the break point, and the calculated tensile strength after the break was recorded.

[0108] As a result, as shown in Table 3 below, it was confirmed that the positive electrode of Example 1 exhibited a tensile strength approximately 9% higher than that of the positive electrode of Comparative Example 1, despite containing a smaller amount of binder.

[0109] [Table 3]

[0110] Example 2.

[0111] A solid-state battery was manufactured by sequentially stacking a negative electrode current collector (Cu foil), a sulfide-based solid electrolyte membrane consisting of lithium metal and Li6PS5Cl, and the positive electrode and positive electrode current collector (Al foil) from Example 1. Here, portions of the positive and negative electrode current collectors were made to protrude outside the pouch to maintain the battery's vacuum, and these protruding portions served as the positive and negative electrode terminals. Furthermore, this solid-state battery was subjected to hydrostatic treatment at 500 MPa for 30 minutes. Such hydrostatic treatment significantly improves the battery's characteristics.

[0112] Comparative Example 2.

[0113] A solid-state battery was manufactured using the same method as in Example 2, except that the positive electrode from Comparative Example 1 was used as the positive electrode.

[0114] Evaluation Example 3. Evaluation of Monocell Performance

[0115] The all-solid-state batteries (pouch-type monocells) of Example 2 and Comparative Example 2 were driven under the following charge-discharge conditions with an operating voltage range of 4.25V-3.0V and a driving temperature of 60°C. The discharge capacity retention rates for 0.33C, 0.5C, and 1.0C were evaluated relative to the discharge capacity after the second discharge of 0.1C, and the results are shown in Table 4 below.

[0116] Charging conditions: 0.1C, 4.25V CC / CV, 0.05C cut-off Discharge conditions: 0.1C twice, 0.33C, 0.5C or 1.0C, 3.0V, CC

[0117] [Table 4]

[0118] As a result, it was confirmed that the discharge capacity maintenance rate of Example 2 was higher than that of Comparative Example 2 at a high C rate. This is likely because, in Example 2, the bonding between the positive electrode components was strong, securing electron transfer paths and lithium ion paths, and effectively controlling the decrease in discharge capacity even at a high C rate.

Claims

1. A positive electrode containing 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 includes a core portion containing a carbon-based conductive material and a coating portion located on at least a part of the core portion and containing polymer nanoparticles. The positive electrode is characterized in that the polymer nanoparticles are a copolymer of polyvinylidene fluoride (PVDF) and a comonomer, and the comonomer is one or more selected from the group consisting of hexafluoropropylene (HFP), chlorotrifluoroethylene (CTFE), hexafluoroacetone (HFA), 1-hydropentafluoropropylene (HPFP), tetrafluoroethylene (TFE), and trifluoroethylene (TrFE).

2. The positive electrode according to claim 1, characterized in that the fibrous binder is polytetrafluoroethylene (PTFE).

3. The positive electrode according to claim 1, characterized in that it contains 1.2 parts by weight or less of a fibrous binder with respect to 100 parts by weight of the positive electrode active material layer.

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

5. The positive electrode according to claim 1, characterized in that the polymer nanoparticles have a polymerization ratio between polyvinylidene fluoride (PVDF) and comonomers in the range of 99:1 to 75:

25.

6. The positive electrode according to claim 1, characterized in that the carbon-based conductive material is one or more selected from the group consisting of graphite, carbon black, or carbon fiber.

7. The BET specific surface area of ​​the carbon-based conductive material is 10 m². ２ The positive electrode according to claim 1, characterized in that it is less than or equal to / g.

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

9. The sulfide-based solid electrolyte is Li ２ S - P ２ S ５ -Li ２ O, Li ２ S - P 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 S - P ２ S ５ 、Li ２ S - P ２ S ５ -LiX (X is a halogen element), Li ２ S - B ２ S ３ 、Li ２ S - P ２ S ５ -Z ｍ S ｎ (m, n are positive numbers), Z is one of Ge, Zn, or Ga, Li ２ 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 The positive electrode according to claim 1, characterized in that it is one or more selected from the group including (0 ≤ x ≤ 2).

10. The positive electrode according to claim 1, characterized in that it is a dry positive electrode.

11. An all-solid-state battery comprising a positive electrode, a solid electrolyte layer, and a negative electrode, The positive electrode includes 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 includes a core portion containing a carbon-based conductive material and a coating portion located on at least a part of the core portion and containing polymer nanoparticles. The polymer nanoparticles are a copolymer of polyvinylidene fluoride (PVDF) and a comonomer, and the comonomer is one or more selected from the group consisting of hexafluoropropylene (HFP), chlorotrifluoroethylene (CTFE), hexafluoroacetone (HFA), 1-hydropentafluoropropylene (HPFP), tetrafluoroethylene (TFE), and trifluoroethylene (TrFE), characterized in that the all-solid-state battery.

12. The all-solid-state battery according to claim 11, characterized in that the solid electrolyte layer includes one or more selected from the group including sulfide-based solid electrolytes, oxide-based solid electrolytes, and halide-based solid electrolytes.

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