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

Abstract

This invention relates to a positive electrode for an all-solid-state battery and an all-solid-state battery including the same. The positive electrode for the all-solid-state battery comprises a binder matrix and a composite active material embedded in the binder matrix. The composite active material comprises: a core, the core including a positive electrode active material and a conductive material attached to the surface of the positive electrode active material; and an electrolyte layer disposed on the surface of the core.

Description

Technical Field

[0001] The implementation relates to a positive electrode for an all-solid-state battery and an all-solid-state battery including the same. Background Technology

[0002] Recently, there has been rapid development in battery-powered electronic devices such as mobile phones, laptops, and electric vehicles.

[0003] This type of battery primarily uses rechargeable lithium-ion batteries, and currently commercially available rechargeable lithium-ion batteries use graphite, silicon, or a combination thereof as the negative electrode active material. However, there is a growing need for increasingly higher energy densities, which rechargeable lithium-ion batteries using graphite, silicon, or a combination thereof as the negative electrode active material cannot meet. Furthermore, safety concerns regarding rechargeable lithium-ion batteries are emerging.

[0004] Therefore, the development of all-solid-state batteries using lithium metal as the negative electrode is underway. All-solid-state batteries are those in which all materials are solid, and for example, use a solid electrolyte. Lithium metal exhibits a high average voltage due to its large potential difference with the positive electrode, and can achieve a high energy density with a theoretical capacity of approximately 3860 mAh / g. Furthermore, due to the use of a solid electrolyte, it demonstrates improved safety compared to batteries using liquid electrolytes. Summary of the Invention

[0005] Technical issues

[0006] One embodiment provides a positive electrode for all-solid-state batteries that exhibits excellent electrochemical properties.

[0007] Another embodiment provides an all-solid-state battery including the positive electrode.

[0008] Technical solution

[0009] One embodiment provides a positive electrode for an all-solid-state battery, comprising a binder matrix; and a composite active material embedded in the binder matrix, wherein the composite active material comprises: a core including a positive electrode active material and a conductive material attached to a surface of the positive electrode active material; and an electrolyte layer disposed on a surface of the core.

[0010] Another embodiment provides an all-solid-state battery, which includes a positive electrode; a negative electrode; and a solid electrolyte layer disposed between the positive electrode and the negative electrode.

[0011] Beneficial effects

[0012] According to one embodiment, by using a small amount of binder, the positive electrode for an all-solid-state battery can exhibit excellent electrochemical properties. Attached Figure Description

[0013] Figure 1 This is a schematic diagram illustrating a composite active material for an all-solid-state battery according to one embodiment.

[0014] Figure 2 This is a schematic diagram showing a portion of the positive electrode for an all-solid-state battery according to one embodiment.

[0015] Figure 3 This is a schematic cross-sectional view of an all-solid-state battery according to one embodiment.

[0016] Figure 4 This is a schematic cross-sectional view of an all-solid-state battery according to another embodiment. Detailed Implementation

[0017] Embodiments of the invention are described in detail below. However, these embodiments are provided by way of example, and the disclosure is not limited thereto, and is to be defined by the scope of the claims described later.

[0018] The terminology used in this specification is for illustrative purposes and is not intended to be limiting. Unless the context clearly specifies otherwise, singular expressions include plural expressions.

[0019] The term "combination thereof" may include mixtures, laminates, complexes, copolymers, alloys, blends, reaction products, etc. of the constituent elements.

[0020] The terms “comprising,” “including,” or “having” are used to indicate the presence of the features, figures, steps, components, or combinations thereof, but it should be understood that the possibility of the presence or addition of one or more other features, figures, steps, components, or combinations thereof is not excluded in advance.

[0021] Throughout this specification, unless explicitly stated otherwise, the word “comprising” will be understood to imply the inclusion of the stated elements, but does not exclude any other elements.

[0022] The terms “about” and “substantially” as used throughout this specification mean, as presented, the inherent allowable errors in preparation and materials, and are used in the sense of being close to or near that value. They are intended to aid in understanding the invention and to prevent irresponsible infringers from unfairly exploiting the disclosure of precise or absolute values ​​mentioned herein.

[0023] In the specification, A and / or B, as well as A or B, are not exclusive terms and indicate A, B, or both A and B.

[0024] Unless otherwise defined in the specification, it will be understood that when an element such as a layer, film, region, plate, etc. is referred to as being "on" or "above" another element, it may be directly on, directly connected to, or coupled to the other element, or one or more intermediate elements may be present.

[0025] As used herein, “particle size” or “particle diameter” may refer to the average particle diameter. The average particle diameter can be defined as the average particle diameter D50, which indicates the diameter of the particle at the 50% cumulative volume point of the cumulative size distribution curve. Particle diameter can be measured by methods known to those skilled in the art, such as by a particle size analyzer or by transmission electron microscopy, scanning electron microscopy, or field emission scanning electron microscopy (FE-SEM). In another embodiment, particle diameter can be determined by measuring and analyzing the data using a dynamic light scattering measurement device, counting the number of particles for each particle size range, and calculating the average particle diameter (D50) value therefrom, or by measuring the particle diameter using a laser diffraction method. Laser diffraction can be performed more specifically by distributing the particles to be measured in a distribution solvent and introducing them into a commercially available laser diffraction particle measurement device (e.g., the MT 3000 from Microtrac, Inc.), irradiating them with ultrasound at a power of 60 W at approximately 28 kHz, and calculating the average particle diameter (D50) of the 50% standard of the particle distribution in the measurement device.

[0026] The term "thickness" can be measured by taking a photograph with an optical microscope, such as a scanning electron microscope.

[0027] One embodiment provides a positive electrode for an all-solid-state battery, the positive electrode comprising a binder matrix and a composite active material embedded in the binder matrix. According to one embodiment, the positive electrode comprises a positive electrode active material layer composed of the composite active material and a positive electrode current collector supporting the positive electrode active material layer.

[0028] The composite active material may include: a core comprising a positive electrode active material and a conductive material attached to the surface of the positive electrode active material; and an electrolyte layer disposed on the surface of the core. The electrolyte layer may be disposed by substantially completely surrounding the surface of the core, or by partially covering the surface of the core.

[0029] Figure 1 The composite active material 1 is schematically shown, comprising a core and an electrolyte layer 7 disposed on the surface of the core. The core includes a positive electrode active material 3 and a conductive material 5 attached to the surface of the positive electrode active material 3. Although Figure 1 The conductive material 5 is shown not to be covered by the electrolyte layer 7, but this disclosure is not limited thereto, and the conductive material may be completely covered by the electrolyte layer.

[0030] Figure 2 Schematic display including Figure 1 The diagram shows a partial view of the positive electrode 10 of the composite active material, wherein the composite active material is embedded in the binder matrix 9.

[0031] In one embodiment, the binder matrix may consist of a fibrous binder that does not react with solid electrolytes, such as a fibrous binder that does not react with sulfide-based solid electrolytes. For example, the fibrous binder may be a fibrillated polymer selected from polytetrafluoroethylene, polyvinyl alcohol, polyvinylidene fluoride, or combinations thereof. The fibrous binder may also be nanofibers.

[0032] Because fibrous binders are adhesive, it is not necessary to prepare a liquid phase by adding the fibrous binder to a solvent.

[0033] In one embodiment, the amount of binder matrix can be from 0.1 wt% to 10 wt% based on the total weight of the positive electrode, and can also be from 0.1 wt% to 5 wt% or from 0.1 wt% to 2 wt%. If the amount of binder matrix is ​​included in the above ranges, lithium-ion conduction channels and electron conduction channels can be sufficiently formed.

[0034] In one embodiment of the positive electrode, the positive electrode active material is included as a composite active material, and the composite active material may exist in an embedded form within the binder matrix. For example, the composite active material may be attached to a fibrous binder constituting the binder matrix, and thus may exist in an embedded form within the matrix.

[0035] The composite active material includes a core and a solid electrolyte layer surrounding the surface of the core, wherein the core may include a positive electrode active material and a conductive material attached to the surface of the positive electrode active material.

[0036] Based on the total weight of the positive electrode, the amount of conductive material can be from 0.1 wt% to 10 wt%, or from 0.1 wt% to 5 wt% or from 0.1 wt% to 1 wt%.

[0037] The amount of electrolyte can be from 3% to 20% by weight, or from 3% to 15% by weight or from 7% to 14% by weight, depending on the total weight of the positive electrode.

[0038] In one embodiment, it is preferable that the amount of conductive material is within the aforementioned range and is less than the amount of electrolyte. If the conductive material is within the aforementioned range, for example, if it is included in the positive electrode in an amount less than that of electrolyte, the reduced amount of conductive material with a large surface area results in a reduction in the binder dosage, thereby improving electrochemical properties and increasing the density of the active material.

[0039] In one embodiment, a conductive material is included to provide electrode conductivity, and any electrically conductive material may be used as the conductive material unless it causes a chemical change. Examples of conductive materials may include carbon-based materials, metal-based materials, conductive polymers, or combinations thereof. Examples of conductive materials may include: carbon-based materials, such as carbon black, acetylene black, Ketjen black, carbon fibers, carbon nanofibers, graphene, carbon nanotubes, etc.; metal-based materials of metal powder or metal fibers, including copper, nickel, aluminum, silver, etc.; conductive polymers, such as polyphenylene derivatives; or mixtures thereof.

[0040] The electrolyte can be a solid electrolyte, and for example, it can be an inorganic solid electrolyte such as a sulfide solid electrolyte, an oxide solid electrolyte or a halide solid electrolyte, or it can be a solid polymer electrolyte.

[0041] In one embodiment, the sulfide solid electrolyte may be Li2S-P2S5, Li2S-P2S5-LiX (where X is a halogen element, such as I or Cl), Li2S-P2S5-Li2O, Li2S-P2S5-Li2O-LiI, Li2S-SiS2, Li2S-SiS2-LiI, Li2S-SiS2-LiBr, Li2S-SiS2-LiCl, Li2S-SiS2-B2S3-LiI, Li2S-SiS2-P2S5-LiI, Li2S-B2S3, or Li2S-P2S5-Z. m S n (where m and n are each an integer from 0 to 12 or less, and Z is one of Ge, Zn, or Ga), Li2S-GeS2, Li2S-SiS2-Li3PO4, Li2S-SiS2-Li p MO q (where p and q are each an integer from 0 to 12 or less, and M is one of P, Si, Ge, B, Al, Ga, and In), Li a M b P c S d A e (Where a, b, c, d, and e are each an integer from 0 to 12 or less, M is Ge, Sn, Si, or a combination thereof, and A is one of F, Cl, Br, or I). Sulfide-based solid electrolytes can be, for example, Li. 7-x PS 6-x F x (0≤x≤2), Li 7-x PS 6-x Cl x (0≤x≤2), Li 7-x PS 6-x Br x (0≤x≤2) or Li7-x PS 6- x I x (0≤x≤2). In some implementations, it can be Li3PS4 or Li7P3S. 11 , Li7PS6, Li6PS5Cl, Li6PS5Cl, Li6PS5I, Li6PS5Br, Li 5.8 PS 4.8 Cl 1.2 Li 6.2 PS 5.2 Br 0.8 wait.

[0042] In one embodiment, the sulfide solid electrolyte may be a sulfide solid electrolyte of the argentite-germanium type. The sulfide solid electrolyte of the argentite-germanium type may be, for example, Li... a M b P c S d A e (where a, b, c, d, and e are each an integer of 0 or greater and 12 or less, and M is Ge, Sn, Si, or a combination thereof, and A is F, Cl, Br, or I), and in some embodiments, it may be Li3PS4 or Li7P3S. 11 , Li7PS6, Li6PS5Cl, Li6PS5Br, Li6PS5I, Li 5.8 PS 4.8 Cl 1.2 Li 6.2 PS 5.2 Br 0.8 wait.

[0043] Sulfide solid electrolytes can be amorphous, crystalline, or a combination thereof. Sulfide solid electrolytes can be prepared, for example, by mixing Li₂S and P₂S₅ in a molar ratio of 50:50 to 90:10 or 50:50 to 80:20. Within these mixing ratios, sulfide solid electrolytes exhibiting excellent ionic conductivity can be prepared. Ionic conductivity can be further improved by additionally including other components such as SiS₂, GeS₂, B₂S₃, etc. As mixing methods, mechanical milling or solution methods can be applied. Mechanical milling is a method in which starting materials and a ball mill, etc., are placed in a reactor and vigorously stirred to pulverize the starting materials into fine particles and mix them. Solution methods provide a solid electrolyte as a precipitate by mixing the starting materials in a solvent. Furthermore, calcination can be performed after mixing. If additional calcination is performed, the crystals of the solid electrolyte can become more robust.

[0044] Sulfide solid electrolytes can be commercially available solid electrolytes.

[0045] Oxide-based solid electrolytes can be, for example, Li 1+x Ti 2-x Al(PO4)3 (LTAP) (0 ≤ x ≤ 4), Li 1+x+y Al x Ti 2- x Si y P 3-y O 12 (0 < x < 2, 0 ≤ y < 3), BaTiO3, Pb(Zr,Ti)O3 (PZT), Pb 1-x La x Zr 1-y Ti y O3 (PLZT) (0 ≤ x < 1, 0 ≤ y < 1), Pb(Mg3Nb 2 / 3 )O3 - PbTiO3 (PMN - PT), HfO2, SrTiO3, SnO2, CeO2, Na2O, MgO, NiO, CaO, BaO, ZnO, ZrO2, Y2O3, Al2O3, TiO2, SiO2, lithium phosphate (Li3PO4), lithium titanium phosphate (Li x Ti y (PO4)3, 0 < x < 2, 0 < y < 3), Li 1+x+y (Al, Ga) x (Ti, Ge) 2-x Si y P 3-y O 12 (0 ≤ x ≤ 1, 0 ≤ y ≤ 1), lanthanum lithium titanate (Li x La y TiO3, 0 < x < 2, 0 < y < 3), Li2O, LiAlO2, Li2O - Al2O3 - SiO2 - P2O5 - TiO2 - GeO2 - based ceramics, garnet - based ceramics Li 3+x La3M2O 12 (M is Te, Nb or Zr, and x is an integer from 1 to 10) or a mixture thereof.

[0046] Solid polymer electrolytes can include at least one selected from, for example, the following: polyethylene oxide, poly(trifluoromethanesulfonyl imide)(diallyldimethylammonium) (polyTFSI(diallyldimethylammonium)), Cu3N, Li3N, LiPON, Li3PO4·Li2S·SiS2, Li2S·GeS2·Ga2S3, Li2O·11Al2O3, Na2O·11Al2O3, (Na,Li) 1+x Ti 2-x Al x (PO4)3 (0.1 ≤ x ≤ 0.9), Li1+x Hf 2-x Al x (PO4)3 (0.1 ≤ x ≤ 0.9), Na3Zr2Si2PO 12 , Li3Zr2Si2PO 12 , Na5ZrP3O 12 , Na5TiP3O 12 , Na3Fe2P3O 12 , Na4NbP3O 12 , Na-silicate, Li 0.3 La 0.5 TiO3, Na5MSi4O 12 (where M is a rare earth element such as Nd, Gd, Dy, etc.) Li5ZrP3O 12 , Li5TiP3O 12 , Li3Fe2P3O 12 , Li4NbP3O 12 , Li 1+x (M, Al, Ga) x (Ge 1-y Ti y ) 2-x (PO4)3 (0 ≤ x ≤ 0.8, 0 ≤ y ≤ 1.0, and M is Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm or Yb), Li 1+x+y Q x Ti 2- x Si y P 3-y O 12 (0 < x ≤ 0.4, 0 < y ≤ 0.6, and Q is Al or Ga), Li6BaLa2Ta2O 12 , Li7La3Zr2O 12 , Li5La3Nb2O 12 , Li5La3M2O 12 (where M is Nb, Ta) or Li 7+x A x La 3-x Zr2O 12 (0 < x < 3, and A is Zn).

[0047] Halide solid electrolytes may include Li element, M element (where M is a metal other than Li), and X element (where X is a halogen). X can be, for example, F, Cl, Br, and I. In some embodiments, the halide solid electrolyte may include at least one of Br and Cl as X. M can be, for example, metal elements such as Sc, Y, B, Al, Ga, In, etc.

[0048] The composition of the halide-based solid electrolyte is not limited, but the halide-based solid electrolyte may be composed of Li 6- 3a M a Br b Cl c (where M is a metal other than Li, 0 < a < 2, 0 ≤ b ≤ 6, 0 ≤ c ≤ 6, and b + c = 6). a can be 0.75 or greater or 1 or greater, and a can be 1.5 or less. b can be 1 or greater or 2 or greater. c can be 3 or greater or 4 or greater. Examples of the halide-based solid electrolyte may be Li3YBr6, Li3YCl6, or Li3YBr2Cl4.

[0049] The solid electrolyte may have a particulate shape and may have an average particle diameter D50 of 5.0 μm or less, such as 0.1 μm to 5.0 μm, 0.5 μm to 5.0 μm, 0.5 μm to 4.0 μm, 0.5 μm to 3.0 μm, 0.5 μm to 2.0 μm, or 0.5 μm to 1.0 μm.

[0050] In some embodiments, the positive electrode active material may be a positive electrode active material capable of reversibly intercalating and deintercalating lithium ions. For example, the positive electrode active material may include one or more composite oxides of a metal selected from cobalt, manganese, nickel, and combinations thereof with lithium. Examples of the positive electrode active material may be Li a A 1-b B 1 b D 1 2 (0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5); Li a E 1- b B 1 b O 2-c D 1 c (0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.5); Li a E 2-b B 1 b O 4-c D 1 c (0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 05); Li a Ni 1-b-c Co b B 1 c D 1 α (0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.5, 0 < α ≤ 2); Li aNi 1-b-c Co b B 1 c O 2-α F 1 α (0.90≤a≤1.8,0≤b≤0.5,0≤c≤0.5,0<α<2);Li a Ni 1-b-c Co b B 1 c O 2-α F 1 2(0.90≤a≤1.8,0≤b≤0.5,0≤c≤0.5,0<α<2);Li a Ni 1-b-c Mr b B 1 c D 1 α (0.90≤a≤1.8,0≤b≤0.5,0≤c≤0.5,0<α≤2);Li a Ni 1-b-c Mr b B 1 c O 2-α F 1 α (0.90≤a≤1.8,0≤b≤0.5,0≤c≤0.5,0<α<2); Li a Ni 1-b-c Mr b B 1 c O 2-α F 1 2(0.90≤a≤1.8,0≤b≤0.5,0≤c≤0.5,0<α<2);Li a Ni b HAVE BEEN c G d O2(0.90≤a≤1.8,0≤b≤0.9,0≤c≤0.5,0.001≤d≤0.1);Li a Ni b Co c L 1 d G e O2(0.90≤a≤1.8,0≤b≤0.9,0≤c≤0.5,0≤d≤0.5,0≤e≤0.1);Li a NiG b O2(0.90≤a≤1.8,0.001≤b≤0.1);Li a CoGb O2 (0.90 ≤ a ≤ 1.8, 0.001 ≤ b ≤ 0.1); Li a MnG b O2 (0.90 ≤ a ≤ 1.8, 0.001 ≤ b ≤ 0.1); Li a Mn2G b O4 (0.90 ≤ a ≤ 1.8, 0.001 ≤ b ≤ 0.1); QO2; QS2; LiQS2; V2O5; LiV2O5; LiI 1 O2; LiNiVO4; Li (3-f) J2(PO4)3 (0 ≤ f ≤ 2); Li (3-f) Fe2(PO4)3 (0 ≤ f ≤ 2); or LiFePO4.

[0051] In the chemical formula, A is selected from Ni, Co, Mn, or a combination thereof; B 1 is selected from Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, rare earth elements, or a combination thereof; D 1 is selected from O, F, S, P, or a combination thereof; E is selected from Co, Mn, or a combination thereof; F 1 is selected from F, S, P, or a combination thereof; G is selected from Al, Cr, Mn, Fe, Mg, La, Ce, Sr, V, or a combination thereof; Q is selected from Ti, Mo, Mn, or a combination thereof; I 1 is selected from Cr, V, Fe, Sc, Y, or a combination thereof; J is selected from V, Cr, Mn, Co, Ni, Cu, or a combination thereof; L 1 is selected from Mn, Al, or a combination thereof.

[0052] According to some embodiments, the positive electrode active material can be a ternary lithium transition metal oxide such as LiNi x Co y Al z O2 (NCA), LiNi x Co y Mn z O2 (NCM) (where 0 < x < 1, 0 < y < 1, 0 < z < 1, x + y + z = 1), etc.

[0053] The compound may have a coating (coating layer) on the surface, or may be mixed with other compounds having a coating. The coating may include at least one coating element compound selected from: oxides of the coating element, hydroxides of the coating element, hydroxyoxides of the coating element, oxycarbonates of the coating element, and hydroxycarbonates of the coating element. The compound used for the coating may be amorphous or crystalline. Coating elements included in the coating may include Mg, Al, Co, K, Na, Ca, Si, Ti, V, Sn, Ge, Ga, B, As, Zr, or mixtures thereof. The coating may be formed by any coating method, such as spraying, dipping, etc., that will not adversely affect the properties of the positive electrode active material, and is not shown in detail because such methods will be readily understood by those skilled in the art.

[0054] The coating can be any coating material known as a coating for the positive electrode active material of an all-solid-state battery, and examples include Li2O-ZrO2 (LZO), etc.

[0055] If the positive electrode active material is a ternary material including nickel, cobalt, and manganese, or nickel, cobalt, and aluminum, the capacity density of the all-solid-state battery can be further improved, and the metal leaching from the positive electrode active material during charging can be further reduced. This allows for further improvements in the long-term reliability and cycle characteristics of the all-solid-state battery during charging.

[0056] Here, the positive electrode active material may have a shape, for example, a particle shape such as spherical, ellipsoidal, etc. In some embodiments, the average particle size of the positive electrode active material is not particularly limited, and can be within the range suitable for positive electrode active materials of conventional all-solid-state secondary batteries.

[0057] In some embodiments, based on a total of 100% by weight of the positive electrode, the amount of the positive electrode active material may be 75% to 94% by weight or 87% to 92% by weight.

[0058] According to one embodiment, the positive electrode for an all-solid-state battery can be a sheet-type positive electrode. A sheet-type positive electrode refers to a positive electrode in which the positive electrode active material layer is formed in a sheet shape.

[0059] The positive electrode current collector loaded with the positive electrode active material layer may include, for example, indium (In), copper (Cu), magnesium (Mg), stainless steel, titanium (Ti), iron (Fe), cobalt (Co), nickel (Ni), zinc (Zn), aluminum (Al), germanium (Ge), lithium (Li) or alloys thereof, and may be in foil or sheet form.

[0060] In some embodiments, the thickness of the positive electrode active material layer can be from 70 μm to 500 μm or from 150 μm to 300 μm. If the thickness of the positive electrode active material layer is within these ranges, the electrode is flexible and thus further suppresses the occurrence of cracks and short circuits due to impact, thereby exhibiting further improved safety.

[0061] The following describes the fabrication of a positive electrode for an all-solid-state battery. In the fabrication, the mixing ratio is described based on the weight ratio in the final positive electrode. For example, the amount ratio of each component in 100% by weight of the positive electrode is described.

[0062] A mixture is prepared by mixing the positive electrode active material and the first conductive material.

[0063] The mixing ratio of the positive electrode active material and the first conductive material can be in the range of 85:0.5 to 94:5 by weight, or in the range of 85:0.1 to 94:0.2 by weight. If the mixing ratio of the positive electrode active material and the conductive material is within the above range, the conductive material can more appropriately cover the active material to better maintain the conductive path.

[0064] The mixing process of the positive electrode active material and the first conductive material can be carried out at a stirring speed of 1000 rpm to 5000 rpm or 1000 rpm to 3000 rpm. The mixing process can be carried out for 1 minute to 10 minutes or 3 minutes to 7 minutes.

[0065] If the mixing process is carried out at the specified stirring speed for the specified time, the conductive material can be well mixed with the positive electrode active material without any interruption phenomenon in which the conductive material is cut off, thereby allowing the conductive path of the conductive material to be well maintained, and thus achieving the effect of improved high-rate characteristics.

[0066] The mixture is mixed with a first solid electrolyte to prepare an electrolyte mixture.

[0067] Based on a total electrolyte mixture of 100% by weight, the amount of the first solid electrolyte used can be from 0.1% to 2% by weight or from 0.5% to 1% by weight. If the amount of solid electrolyte used is within the range described above, the electrolyte can be uniformly distributed and the density can be increased.

[0068] The mixing process of the mixture and the first solid electrolyte can be carried out at a mixing speed of 1000 rpm to 10000 rpm or 1000 rpm to 3000 rpm. The mixing process can be carried out for 1 minute to 10 minutes or 1 minute to 7 minutes.

[0069] The resulting electrolyte mixture, the second conductive material, the second solid electrolyte, and the binder are mixed to prepare the binder mixture. The mixing process can be carried out at a mixing speed of 1000 rpm to 10000 rpm, 1000 rpm to 3000 rpm, or 1000 rpm to 2200 rpm. The mixing process can be carried out 1 to 15 times or 1 to 10 times, wherein each mixing process is carried out for 1 minute to 10 minutes or 1 minute to 7 minutes.

[0070] The first conductive material and the second conductive material are as described above, and may be the same as or different from each other. Furthermore, the first solid electrolyte and the second solid electrolyte are as described above, and may be the same as or different from each other.

[0071] Based on a total of 100% by weight of binder mixture, the amount of binder used can be from 0.1% by weight to 5% by weight or from 0.1% by weight to 1% by weight. If the amount of binder used is within the above range, a coating can be prepared with a small amount of binder.

[0072] The binder mixture is extruded to prepare the positive electrode active material layer.

[0073] The extrusion process can be performed using an extruder at a temperature of 50°C to 100°C, a screw speed of 50 rpm to 200 rpm, and a torque setting of 1 to 5 during extrusion. The torque setting can be controlled by the amount of binder mixture fed into the extruder; for example, the binder mixture can be fed at a rate of 500 g / h to 2000 g / h. For example, torque settings 1 to 2 can correspond to feed rates of 500 g / h to 900 g / h, torque settings 3 to 4 can correspond to feed rates greater than 900 g / h and 1200 g / h or less, and torque setting 5 can correspond to feed rates greater than 1200 g / h and less than 1400 g / h.

[0074] If the extrusion process is carried out under the above conditions, the desired positive electrode active material layer, especially the sheet-type positive electrode active material layer, can be appropriately prepared.

[0075] After the extrusion process, deagglomeration of the extruded product can be further performed. The deagglomeration process can be carried out at a speed of 5000 rpm to 20000 rpm or 7000 rpm to 15000 rpm for 1 minute to 10 minutes or 1 minute to 5 minutes.

[0076] Furthermore, the product obtained from extrusion or deagglomeration can be further subjected to a pressing process. The pressing process can be performed as a roll pressing process. This process can be carried out at 20°C to 100°C or 30°C to 80°C. Additionally, the roller speed can be 1 rpm to 10 rpm or 2 rpm to 5 rpm.

[0077] A current collector is placed on the prepared positive electrode active material layer to prepare the positive electrode. The process of placing the current collector can be carried out before battery manufacturing, wherein the current collector can be placed on the positive electrode active material layer, and during battery manufacturing, after the positive electrode active material layer is placed in contact with the solid electrolyte layer, the current collector can also be placed on the other side of the positive electrode active material layer that is not in contact with the solid electrolyte layer.

[0078] Another embodiment provides an all-solid-state battery including a positive electrode. The all-solid-state battery includes a negative electrode and a solid electrolyte layer located between the positive and negative electrodes.

[0079] The negative electrode includes a current collector and a negative electrode layer located on one surface of the current collector.

[0080] The negative electrode layer may be a negative electrode active material layer or a negative electrode coating. Alternatively, the negative electrode layer may be a lithium metal layer.

[0081] The negative electrode active material layer includes a negative electrode active material and may include a binder, a conductive material, and / or a solid electrolyte.

[0082] The negative electrode active material may include materials capable of reversibly inserting / deintercalating lithium ions, lithium metal, lithium metal alloys, materials capable of doping and dedoping lithium, or transition metal oxides.

[0083] Materials capable of reversibly inserting / deintercalating lithium ions can be carbon-based negative electrode active materials, which may include, for example, crystalline carbon, amorphous carbon, or combinations thereof. Examples of crystalline carbon may include graphite such as unspecified (non-defined shape), plate-shaped, flake-shaped, spherical, or fibrous natural or artificial graphite, and examples of amorphous carbon may include soft or hard carbon, mesophase pitch carbides, calcined coke, etc.

[0084] As an alloy of lithium metal, lithium can be used in combination with one or more metals selected from Na, K, Rb, Cs, Fr, Be, Mg, Ca, Sr, Si, Sb, Pb, In, Zn, Ba, Ra, Ge, Al and Sn.

[0085] Materials capable of doping and dedoping lithium can be Si-based or Sn-based negative electrode active materials. Si-based negative electrode active materials can be silicon, silicon-carbon composites, or SiO2. x(0 < x < 2), a Si-Q alloy (where Q is an element selected from the following: alkali metals, alkaline earth metals, group 13 elements, group 14 elements other than Si, group 15 elements, group 16 elements, transition metals, rare earth elements, and combinations thereof) or a combination thereof. The Sn-based negative electrode active material can be Sn, SnO2, a Sn-R alloy (where R is an element selected from the following: alkali metals, alkaline earth metals, group 13 elements, group 14 elements, group 15 elements, group 16 elements, transition metals, rare earth elements, and combinations thereof, but not Sn), etc. Additionally, at least one of these mixed with SiO2 can also be used. The elements Q and R can be selected from Mg, Ca, Sr, Ba, Ra, Sc, Y, Ti, Zr, Hf, Rf, V, Nb, Ta, Db, Cr, Mo, W, Sg, Tc, Re, Bh, Fe, Pb, Ru, Os, Hs, Rh, Ir, Pd, Pt, Cu, Ag, Au, Zn, Cd, B, Al, Ga, Sn, In, Tl, Ge, P, As, Sb, Bi, S, Se, Te, Po, and combinations thereof.

[0086] The silicon-carbon composite can be, for example, a silicon-carbon composite including the following: a core including crystalline carbon and silicon particles and an amorphous carbon coating on the surface of the core. The crystalline carbon can be artificial graphite, natural graphite, or a combination thereof. As the amorphous carbon precursor, coal-based pitch, mesophase pitch, petroleum-based pitch, coal-based oil, petroleum-based heavy oil, or a polymer resin such as a phenolic resin, furan resin, or polyimide resin can be used. Here, based on the total weight of the silicon-carbon composite, the amount of silicon can be 10 wt% to 50 wt%. In addition, based on the total weight of the silicon-carbon composite, the amount of crystalline carbon can be 10 wt% to 70 wt%, and based on the total weight of the silicon-carbon composite, the amount of amorphous carbon can be 20 wt% to 40 wt%. Additionally, the thickness of the amorphous carbon coating can be 5 nm to 100 nm.

[0087] The silicon particles can have an average particle diameter (D50) of 10 nm to 20 μm, for example, 10 nm to 500 nm. The silicon particles can exist in an oxidized form, and here, the atomic content ratio of Si:O in the silicon particles indicating the degree of oxidation can be 99:1 to 33:67. The silicon particles can be SiO x particles, and here, the range of x in SiO x can be greater than 0 and less than 2. As used herein, the average particle diameter (D50) indicates the diameter of the particles at which the cumulative volume corresponds to 50% by volume in the particle size distribution measured by a particle size analyzer using the laser diffraction method.

[0088] Si-based or Sn-based negative electrode active materials can be used together with carbon-based negative electrode active materials. The mixing ratio of Si-based or Sn-based negative electrode active materials to carbon-based negative electrode active materials can be from 1:99 to 90:10 by weight.

[0089] In the negative electrode active material layer, the amount of negative electrode active material can be from 95% to 99% by weight, based on the total weight of the negative electrode active material layer.

[0090] In one embodiment, the negative electrode active material layer may further include a binder and optionally further include a conductive material. In the negative electrode active material layer, the amount of binder may be from 1% to 5% by weight, based on the total weight of the negative electrode active material layer. Additionally, if a conductive material is further included, the negative electrode active material layer may comprise 90% to 98% by weight of negative electrode active material, 1% to 5% by weight of binder, and 1% to 5% by weight of conductive material.

[0091] The binder is used to ensure good adhesion between the negative electrode active material particles and also to ensure good adhesion between the negative electrode active material and the current collector. The binder can be a non-aqueous binder, an aqueous binder, or a combination thereof.

[0092] Non-aqueous adhesives may include, for example, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, polymers including ethylene oxide (including polymers of ethylene oxide), ethylene propylene copolymers, polystyrene, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, polyamide-imide, polyimide, or combinations thereof.

[0093] Waterborne adhesives may include rubber-based adhesives or polymeric resin adhesives. Rubber-based adhesives may be selected from styrene-butadiene rubber, acrylated styrene-butadiene rubber, acrylonitrile-butadiene rubber, acrylic rubber, butyl rubber, fluororubber, or combinations thereof. Polymeric resin adhesives may be selected from polyethylene oxide, polyvinylpyrrolidone, polyepoxychlorohydrin, polyphosphazene, polyacrylonitrile, ethylene-propylene-diene copolymer, polyvinylpyridine, chlorosulfonated polyethylene, latex, polyester resin, acrylic resin, phenolic resin, epoxy resin, polyvinyl alcohol, or combinations thereof.

[0094] If an aqueous binder is used as the negative electrode binder, a thickener capable of imparting viscosity may be further used, and the thickener may include, for example, a cellulose compound. The cellulose compound may include carboxymethyl cellulose, hydroxypropyl methyl cellulose, methyl cellulose, their alkali metal salts, or combinations thereof. The alkali metal may be Na, K, or Li. Based on 100 parts by weight of the negative electrode active material, the amount of thickener used may be from 0.1 parts by weight to 3 parts by weight. Cellulose compounds may also be used as binders.

[0095] The adhesive is not limited to these, and any material available in the art as an adhesive may be used, and its amount may be appropriately adjusted.

[0096] Conductive materials are used to impart conductivity to electrodes, and examples of conductive materials may be carbon-based materials such as natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, carbon fiber, carbon nanotubes, etc.; metal-based materials including metal powders or metal fibers of copper, nickel, aluminum, silver, etc.; conductive polymers such as polyphenylene derivatives; or mixtures thereof.

[0097] The negative electrode current collector may include one of the following: copper foil, nickel foil, stainless steel foil, titanium foil, nickel foam, copper foam, polymer substrate coated with conductive metal, and combinations thereof.

[0098] If the negative electrode layer is a negative electrode coating, the negative electrode refers to a deposition-type negative electrode. A deposition-type negative electrode means that it does not include negative electrode active material during battery fabrication, but deposits lithium metal or the like during battery charging, and the deposited lithium metal acts as the negative electrode active material. To explain this in more detail, an electrode coating refers to a layer that facilitates the movement of lithium ions released from the positive electrode active material to the negative electrode during charging and discharging of an all-solid-state battery, thereby promoting their deposition on the surface of the current collector. For example, a lithium deposition layer can be formed due to the deposition of lithium ions between the current collector and the negative electrode coating, and this lithium deposition layer acts as the negative electrode active material; this negative electrode is generally referred to as a deposition-type negative electrode. Amorphous carbon and metals included in the negative electrode coating do not act as negative electrode active materials that directly participate in the charging and discharging reactions.

[0099] The negative electrode coating may include a metal, a carbon-based material, or a combination thereof that acts as a catalyst. In the negative electrode coating, for example, the metal may be supported on a carbon-based material, or the metal and carbon-based material may exist in a mixed state. In one embodiment, the negative electrode coating may include a metal and a carbon-based material.

[0100] Carbon-based materials can be, for example, crystalline carbon, amorphous carbon, or combinations thereof, or may be amorphous carbon. Crystalline carbon can be, for example, natural graphite, artificial graphite, mesophase carbon microspheres, carbon nanotubes, graphene, or combinations thereof. Amorphous carbon can be, for example, carbon black, acetylene black, superconducting acetylene black, Ketjen black, furnace black, activated carbon, graphene, or combinations thereof. Carbon black can be Super P (available from Timcal, Ltd.). Amorphous carbon is not limited thereto, and any material that can be classified as amorphous carbon in the art is available.

[0101] Carbon-based materials can be, for example, crystalline carbon, amorphous carbon, or mixtures thereof. Amorphous carbon can be, for example, carbon black, acetylene black, superconducting acetylene black, Ketjen black, furnace black, activated carbon, or combinations thereof. Carbon black can be Super P (available from Timcal, Ltd.). Amorphous carbon can be, for example, natural graphite, synthetic graphite, carbon nanotubes, graphene, or combinations thereof. Crystalline carbon can have an unspecified shape, such as sheet-like, flake-like, spherical, or fibrous.

[0102] In one embodiment, the carbon-based material may be a single particle or an aggregated product having a primary particle agglomeration. If the carbon-based material is a single particle, the size of the carbon-based material may have an average particle size of 100 nm or less, for example, a nanoscale size of 10 nm to 100 nm.

[0103] If the carbon-based material is an agglomeration product, the particle size of the primary particles can be from 20 nm to 100 nm, and the particle size of the secondary particles can be from 1 μm to 20 μm.

[0104] In one embodiment, the particle size of the primary particles may be 20 nm or larger, 30 nm or larger, 40 nm or larger, 50 nm or larger, 60 nm or larger, 70 nm or larger, 80 nm or larger, or 90 nm or larger, and 100 nm or smaller, 90 nm or smaller, 80 nm or smaller, 70 nm or smaller, 60 nm or smaller, 50 nm or smaller, 40 nm or smaller, or 30 nm or smaller.

[0105] In one embodiment, the particle size of the secondary particles may be 1 μm or larger, 3 μm or larger, 5 μm or larger, 7 μm or larger, 10 μm or larger, or 15 μm or larger, and 20 μm or smaller, 15 μm or smaller, 10 μm or smaller, 7 μm or smaller, 5 μm or smaller, or 3 μm or smaller.

[0106] The shape of the primary particles can be spherical, elliptical, plate-shaped, or a combination thereof, and in some embodiments, the shape of the primary particles can be spherical, elliptical, or a combination thereof.

[0107] The metal can be Ag, Au, Sn, Zn, Al, Mg, Ge, Cu, In, Ni, Bi, Pt, Pd, or a combination thereof. Including a metal in the negative electrode coating can further improve the electrical conductivity of the negative electrode.

[0108] The metal can be in the form of nanoparticles, and the size of these nanoparticles, for example, the average size, can range from 5 nm to 80 nm. However, if they are nanoscale, they are suitable for use. Using nanoscale metal nanoparticles can improve the battery characteristics of all-solid-state batteries, such as cycle life. If the metal particle size increases to the micrometer scale, the uniformity of the metal particles in the negative electrode coating can decrease, which can lead to an increase in current density in specific regions and a deterioration in cycle life characteristics, and is therefore undesirable.

[0109] In addition, based on a total of 100% by weight of negative electrode coating, the amount of metal may be 3% to 30% by weight, 4% to 25% by weight, 5% to 20% by weight, or 5% to 15% by weight.

[0110] In addition, based on a total of 100% by weight of negative electrode coating, the carbon-based material may be 70% to 97% by weight, 75% to 96% by weight, 80% to 95% by weight, or 85% to 95% by weight.

[0111] The negative electrode coating may further include an adhesive. The adhesive may be a non-aqueous adhesive.

[0112] Non-aqueous adhesives may be, for example, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, polymers including ethylene oxide (including polymers of ethylene oxide), ethylene-propylene copolymers, polystyrene, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, polyamide-imide, polyimide, polyacrylate, or combinations thereof.

[0113] Based on a total of 100% by weight of the negative electrode coating, the binder may be 1 to 15% by weight. For example, based on a total of 100% by weight of the negative electrode coating, the binder may be 1% or more by weight, 2% or more by weight, 3% or more by weight, 4% or more by weight, 5% or more by weight, 6% or more by weight, 7% or more by weight, 8% or more by weight, 9% or more by weight, 10% or more by weight, 11% or more by weight, 12% or more by weight, 13% or more by weight, or 14% or more by weight and 15% or less by weight, 14% or less by weight, 13% or less by weight, 12% or less by weight, 11% or less by weight, 10% or less by weight, 9% or less by weight, 8% or less by weight, 7% or less by weight, 6% or less by weight, 5% or less by weight, 4% or less by weight, 3% or less by weight, or 2% or less by weight.

[0114] If the binder is included in the negative electrode coating of the all-solid-state battery within the aforementioned weight range, resistance and adhesion can be improved, thereby enhancing the battery characteristics of the all-solid-state battery, such as battery capacity and output characteristics.

[0115] The negative electrode coating may further include additives, such as fillers, dispersants, etc. Additionally, the fillers, dispersants, etc., included in the negative electrode coating may be materials known in the relevant art and commonly used in all-solid-state batteries.

[0116] The negative electrode coating can have a thickness from 1 μm to 20 μm. For example, the thickness of the negative electrode coating can be 1 μm or more, 3 μm or more, 5 μm or more, 20 μm or less, 18 μm or less, 16 μm or less, 14 μm or less, 12 μm or less, or 10 μm or less.

[0117] The current collector can be, for example, indium (In), copper (Cu), magnesium (Mg), stainless steel, titanium (Ti), iron (Fe), cobalt (Co), nickel (Ni), zinc (Zn), aluminum (Al), germanium (Ge), lithium (Li), or alloys thereof, and can be in foil or sheet form. The thickness of the negative electrode current collector can be 1 μm to 20 μm, 5 μm to 15 μm, or 7 μm to 10 μm.

[0118] The current collector may include a metal as a substrate and may further include a thin film on the substrate. The thin film may include, but is not limited to, elements capable of forming alloys with lithium, such as gold, silver, zinc, tin, indium, silicon, aluminum, bismuth, or combinations thereof, and any element known in the art may be used, provided it forms an alloy with lithium. If the current collector further includes a thin film and lithium is deposited during charging to form a lithium-containing layer, a flatter lithium-containing layer can be formed, thereby further improving the cycle life characteristics of the all-solid-state battery.

[0119] The thickness of the film can be 1 nm to 800 nm, 10 nm to 700 nm, 50 nm to 600 nm, or 100 nm to 500 nm. If the thickness of the film is within the range described above, the cycle life characteristics can be further enhanced.

[0120] According to one embodiment, the negative electrode may further include a lithium-containing layer formed between the current collector and the negative electrode coating after battery fabrication during initial charging. The thickness of the lithium-containing layer may be 1 μm to 1000 μm, 1 μm to 500 μm, 1 μm to 200 μm, 1 μm to 150 μm, 1 μm to 100 μm, or 1 μm to 50 μm. If the thickness of the lithium-containing layer falls within the aforementioned range, it can effectively function as a lithium storage device and can further enhance cycle life characteristics.

[0121] The lithium-containing layer can be formed during charging after the battery is manufactured, as lithium ions are released from the positive electrode active material, pass through the solid electrolyte, and migrate toward the negative electrode, and thus lithium precipitates and deposits on the negative electrode current collector.

[0122] Charging can be a formation process, which can be carried out one to three times at about 25°C to 50°C at 0.05C to 1C. If lithium is precipitated and deposited to form a lithium-containing layer, the lithium in the lithium-containing layer is ionized during discharge and moves toward the positive electrode, and therefore, the lithium can be used as a negative electrode active material.

[0123] In one embodiment, when the lithium-containing layer is disposed between the current collector and the negative electrode coating, the negative electrode coating can serve as a protective layer for the lithium-containing layer, and thus suppress the deposition and growth of lithium dendrites. This enables the suppression of capacity decay and short circuits in the all-solid-state battery, thereby improving the cycle life of the all-solid-state battery.

[0124] The solid electrolyte layer includes a solid electrolyte. The solid electrolyte can be an inorganic solid electrolyte such as a sulfide solid electrolyte, an oxide solid electrolyte, a halide solid electrolyte, etc., or a solid polymer electrolyte. Examples of sulfide solid electrolytes, oxide solid electrolytes, halide solid electrolytes, and solid polymer electrolytes are the same as those described above. Furthermore, this solid electrolyte may be the same as or different from the electrolyte used in the positive electrode.

[0125] The solid electrolyte layer may further include a binder. The binder may be, but is not limited to, styrene-butadiene rubber, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, acrylate polymers, or combinations thereof, and may be any material commonly used in the relevant field. The acrylate polymer may be butyl acrylate, polyacrylate, polymethacrylate, or combinations thereof.

[0126] The solid electrolyte layer can be prepared by adding a solid electrolyte to an adhesive solution, coating it onto a substrate film, and then drying it. The adhesive solution may include isobutyl isobutyrate, xylene, toluene, benzene, hexane, or combinations thereof as solvents. The preparation of solid electrolyte layers is well known in the art, and therefore its detailed description will be omitted in this specification.

[0127] In one embodiment, the all-solid-state battery may further include a buffer material that buffers thickness changes that occur during charging and discharging. The buffer material may be located between the negative electrode and the casing, and in the case of a battery in which one or more electrode assemblies are stacked, the buffer material may be located between the different electrode assemblies.

[0128] The cushioning material may include materials having an elastic recovery rate of 50% or greater and insulating properties, and in one embodiment, may include silicone rubber, acrylic rubber, fluorinated rubber, nylon, synthetic rubber, or combinations thereof. The cushioning material may be in the form of a polymer sheet.

[0129] Figure 2 This is a cross-sectional view showing an all-solid-state battery according to one embodiment. (Refer to...) Figure 2 The all-solid-state battery 100 may have a structure in which an electrode assembly is housed in a casing (e.g., a bag), and a negative electrode 400, including a negative electrode current collector 401 and a negative electrode layer 403, a solid electrolyte layer 300, and a positive electrode 200 are stacked in the electrode assembly. The all-solid-state battery 100 may further include an elastic layer 500 disposed on the outside of at least one of the positive electrode 200 and the negative electrode 400. Figure 2 The image shows an electrode assembly including a negative electrode 400, a solid electrolyte layer 300, and a positive electrode 200, but an all-solid-state battery can also be fabricated by stacking at least two electrode assemblies.

[0130] Figure 3 This schematically illustrates an all-solid-state battery according to another embodiment. Figure 3 The all-solid-state battery 100 shown includes a positive electrode 200, a negative electrode 400' including a negative electrode current collector 401' and a negative electrode layer 403', a solid electrolyte 300 between the positive electrode 200 and the negative electrode 400, a battery casing 500 housing these, and a lithium deposition layer 405' between the negative electrode current collector 401' and the negative electrode layer 403'. Such a lithium deposition layer can be formed during charging of the all-solid-state battery because lithium ions are released from the positive electrode active material and deposited on the negative electrode current collector 401'.

[0131] According to one embodiment, an all-solid-state battery can be manufactured by preparing an assembly comprising a negative electrode, a positive electrode, and a solid electrolyte layer disposed between the negative electrode and the positive electrode, and pressing the assembly.

[0132] Pressing can be performed at temperatures ranging from 25°C to 90°C. Furthermore, pressing can be performed at pressures of 550 MPa or less, such as 500 MPa or less, or pressures ranging from 1 MPa to 500 MPa. The pressing time can vary depending on the temperature and pressure; for example, it can be less than 60 minutes. Pressing can be performed using, for example, an isostatic press, a roller press, a plate press, or a warm isostatic press (WIP).

[0133] Modes for carrying out the present invention

[0134] The following describes embodiments and comparative examples of the invention. However, these embodiments should not be construed as limiting the scope of the invention in any way.

[0135] In the following examples and comparative examples, the mixing ratio is described as the weight ratio in the final positive electrode.

[0136] (Example 1)

[0137] (1) Preparation of positive electrode

[0138] LiNi 0.9Mn 0.05 Co 0.05 The O2 positive electrode active material and Ketjen Black conductive material were mixed at a weight ratio of 85:0.1 using a mixer (available from Hosokawa Micron's Nobailta MINI) at 2000 rpm for 2 minutes to prepare a mixture.

[0139] The electrolyte mixture was prepared by mixing the mixture and the silver-germanium sulfide solid electrolyte Li6PS5Cl at a weight ratio of 85.1:0.05 using a mixer (Nobailta MINI) at a stirring speed of 2000 rpm for 5 minutes.

[0140] To prepare the binder mixture, the electrolyte mixture, Ketjen Black conductive material, silver sulfide germanite-type solid electrolyte Li6PS5C, and polytetrafluoroethylene binder were mixed at 2000 rpm for 1 minute using a mixer (THINKY MIXER) in a weight ratio of 85.15:0.3:13.1:1.45, and this process was repeated 10 times.

[0141] The extruded product was prepared by extruding the binder mixture at 60°C using an extruder, wherein the screw speed was 100 rpm and the torque condition was 2 during extrusion (where the binder mixture was fed at 500 g / h).

[0142] The extruded product was crushed at 10,000 rpm for 2 minutes.

[0143] Subsequently, the obtained product was subjected to rolling pressing using two rollers at 60°C and a roller speed of 3 rpm to prepare a sheet-like positive electrode active material layer. The thickness of the prepared sheet-like positive electrode active material layer was 200 μm. The prepared positive electrode active material layer was in a state where the composite active material was embedded in a binder matrix. The composite active material included a core and an electrolyte surrounding the surface of the core. The core included the positive electrode active material and a conductive material attached to the surface of the positive electrode active material.

[0144] The positive electrode is prepared by placing the positive electrode active material layer on the aluminum positive electrode current collector.

[0145] (2) Preparation of negative electrode

[0146] Ag nanoparticles (D50: 60 nm) and carbon black were mixed in an aqueous solvent at a weight ratio of 10:90 to prepare a negative electrode coating slurry. The carbon black was a mixture of single and secondary particles with a particle size of 38 nm, wherein the secondary particles were formed by assembling primary particles with a particle size of 76 nm, and the secondary particles had a particle size of 275 nm.

[0147] A slurry was coated onto a stainless steel foil current collector and vacuum dried at 80°C to prepare a negative electrode comprising a negative electrode coating with a thickness of 12 μm and a current collector with a thickness of 10 μm. The negative electrode coating has a thickness of 12 μm.

[0148] (3) Preparation of solid electrolyte layer

[0149] A solution of isobutyl isobutyrate binder (solids: 50 wt%), including butyl acrylate as an acrylate polymer, was added to and mixed with the silver-germanium sulfide-type solid electrolyte Li6PS5Cl. Here, the mixing ratio of the solid electrolyte to the binder was 98.7:1.3 by weight.

[0150] The mixing process was performed using a Thinky mixer. 2 mm zirconia balls were added to the resulting mixture, and the mixture was stirred again using the Thinky mixer to prepare a slurry. The slurry was cast onto a polytetrafluoroethylene release film and dried at room temperature to prepare a solid electrolyte with a solid electrolyte layer thickness of 100 μm.

[0151] (4) Manufacturing of all-solid-state full-cell cells

[0152] The positive electrode, solid electrolyte, and negative electrode are stacked sequentially and sealed in a bag, and then subjected to isostatic pressing at 80°C and 500 MPa for 30 minutes to produce a rechargeable all-solid-state battery cell (micro battery cell).

[0153] (Example 2)

[0154] The positive electrode was prepared in the same manner as in Example 1, except that the mixing ratio of the mixture and the silver sulfide germanite solid electrolyte Li6PS5Cl was changed to a weight ratio of 85.1:0.1, and the mixing ratio of the electrolyte mixture, Ketjen Black conductive material, silver sulfide germanite solid electrolyte Li6PS5C and polytetrafluoroethylene binder was changed to a weight ratio of 85.2:0.3:13.1:1.4.

[0155] All-solid-state battery cells were manufactured in the same manner as in Example 1 using a positive electrode, a negative electrode from Example 1, and a solid electrolyte from Example 1.

[0156] (Example 3)

[0157] The positive electrode was prepared in the same manner as in Example 1, except that the mixing ratio of the mixture and the silver sulfide germanite solid electrolyte Li6PS5Cl was changed to a weight ratio of 85.1:0.2, and the mixing ratio of the electrolyte mixture, Ketjen Black conductive material, silver sulfide germanite solid electrolyte Li6PS5C and polytetrafluoroethylene binder was changed to a weight ratio of 85.3:0.3:13.1:1.3.

[0158] All-solid-state battery cells were manufactured in the same manner as in Example 1 using a positive electrode, a negative electrode from Example 1, and a solid electrolyte from Example 1.

[0159] (Example 4)

[0160] The positive electrode was prepared in the same manner as in Example 1, except that the mixing ratio of the mixture and the silver sulfide germanite solid electrolyte Li6PS5Cl was changed to a weight ratio of 85.1:0.4, and the mixing ratio of the electrolyte mixture, Ketjen Black conductive material, silver sulfide germanite solid electrolyte Li6PS5C and polytetrafluoroethylene binder was changed to a weight ratio of 85.5:0.3:13.1:1.3.

[0161] All-solid-state battery cells were manufactured in the same manner as in Example 1 using a positive electrode, a negative electrode from Example 1, and a solid electrolyte from Example 1.

[0162] (Example 5)

[0163] The positive electrode was prepared in the same manner as in Example 1, except that LiNi was used. 0.9 Mn 0.05 Co 0.05 The mixing ratio of O2 positive electrode active material and Ketjen black conductive material is changed to a weight ratio of 85.2:0.1, the mixing ratio of the mixture and the argyrodite-type solid electrolyte Li6PS5Cl is changed to a weight ratio of 85.3:0.05, and the mixing ratio of electrolyte mixture, Ketjen black conductive material, argyrodite-type solid electrolyte Li6PS5Cl and polytetrafluoroethylene binder is changed to a weight ratio of 85.35:0.3:13.55:0.8.

[0164] All-solid-state battery cells were manufactured in the same manner as in Example 1 using a positive electrode, a negative electrode from Example 1, and a solid electrolyte from Example 1.

[0165] (Example 6)

[0166] The positive electrode was prepared in the same manner as in Example 1, except that LiNi was used. 0.9 Mn 0.05 Co 0.05 The mixing ratio of O2 positive electrode active material and Ketjen black conductive material is changed to a weight ratio of 85.4:0.1, the mixing ratio of the mixture and the sulfide-germanium ore type solid electrolyte Li6PS5Cl is changed to a weight ratio of 85.5:0.05, and the mixing ratio of electrolyte mixture, Ketjen black conductive material, sulfide-germanium ore type solid electrolyte Li6PS5Cl and polytetrafluoroethylene binder is changed to a weight ratio of 85.55:0.3:13.55:0.6.

[0167] All-solid-state battery cells were manufactured in the same manner as in Example 1 using a positive electrode, a negative electrode from Example 1, and a solid electrolyte from Example 1.

[0168] (Example 7)

[0169] The positive electrode was prepared in the same manner as in Example 1, except that LiNi was used. 0.9 Mn 0.05 Co 0.05 The mixing ratio of O2 positive electrode active material and Ketjen black conductive material was changed to 85.6:0.1 by weight, the mixing ratio of the mixture and the argyrodite-type solid electrolyte Li6PS5Cl was changed to 85.7:0.05 by weight, and the mixing ratio of electrolyte mixture, Ketjen black conductive material, argyrodite-type solid electrolyte Li6PS5Cl and polytetrafluoroethylene binder was changed to 86.75:0.3:13.55:0.4 by weight.

[0170] All-solid-state battery cells were manufactured in the same manner as in Example 1 using a positive electrode, a negative electrode from Example 1, and a solid electrolyte from Example 1.

[0171] (Comparative Example 1)

[0172] (1) Preparation of positive electrode

[0173] LiNi 0.9 Mn 0.05 Co 0.05 The O2 positive electrode active material and Ketjen Black conductive material were mixed at a weight ratio of 85:0.4 using a mixer (available from Hosokawa Micron's Nobailta MINI) at 2000 rpm for 7 minutes to prepare a mixture.

[0174] The binder mixture was prepared by mixing the mixture, the sulfosilgermanium ore type solid electrolyte Li6PS5Cl, and the polytetrafluoroethylene binder at a weight ratio of 85.4:13.6:1 using a mixer (THINKY MIXER) at 2000 rpm for 10 times (1 minute each time).

[0175] The extruded product was prepared by extruding the binder mixture at 60°C using an extruder, wherein the screw speed was 100 rpm and the torque condition was 2 during extrusion (where the binder mixture was fed at 500 g / h).

[0176] The extruded product was crushed at 10,000 rpm for 2 minutes.

[0177] Subsequently, the obtained product was subjected to rolling pressing using two rollers at 60°C and a roller speed of 3 rpm to prepare a sheet-like positive electrode active material layer. The thickness of the prepared sheet-like positive electrode active material layer was 200 μm. The prepared positive electrode active material layer was in a state where the composite active material was embedded in the binder matrix, and the composite active material included the positive electrode active material and a conductive material attached to the surface of the positive electrode active material.

[0178] The positive electrode is prepared by placing the positive electrode active material layer on the aluminum positive electrode current collector.

[0179] (2) Manufacturing of all-solid-state full-cell cells

[0180] The positive electrode, the solid electrolyte of Example 1, and the negative electrode of Example 1 were sequentially stacked and sealed in a bag, and then subjected to isostatic pressing at a high temperature of 80°C and 500 MPa for 30 minutes to produce a rechargeable all-solid-state battery cell (micro battery cell).

[0181] (Comparative Example 2)

[0182] (1) Preparation of positive electrode

[0183] LiNi 0.9 Mn 0.05 Co 0.05 The O2 positive electrode active material, the silver-germanium sulfide solid electrolyte Li6PS5Cl, and the conductive material are mixed at a weight ratio of 85:13.6 using a mixer (available from Hosokawa Micron's Nobailta MINI) at 2000 rpm for 7 minutes.

[0184] To prepare the binder mixture, the solid electrolyte mixture, Ketjen Black conductive material, and polytetrafluoroethylene binder were mixed at 2000 rpm for 1 minute using a mixer (THINKY mixer) in a weight ratio of 98.6:0.4:1, and this process was repeated 10 times.

[0185] The extruded product was prepared by extruding the resulting mixture using an extruder at 60°C, wherein the screw speed was 100 rpm and the torque condition was 2 during extrusion.

[0186] The extruded product was crushed at 10,000 rpm for 2 minutes.

[0187] Subsequently, the obtained product was subjected to rolling pressing using two rollers at 60°C and a roller speed of 3 rpm to prepare a sheet-like positive electrode active material layer. The thickness of the prepared sheet-like positive electrode active material layer was 200 μm. The prepared positive electrode active material layer was in a state where the composite active material was embedded in the binder matrix, and the composite active material included the positive electrode active material and a solid electrolyte layer surrounding the surface of the positive electrode active material.

[0188] The positive electrode is prepared by placing the positive electrode active material layer on the aluminum positive electrode current collector.

[0189] (2) Manufacturing of all-solid-state full-cell cells

[0190] The positive electrode, the solid electrolyte of Example 1, and the negative electrode of Example 1 were sequentially stacked and sealed in a bag, and then subjected to isostatic pressing at a high temperature of 80°C and 500 MPa for 30 minutes to produce a rechargeable all-solid-state battery cell (micro battery cell).

[0191] (Comparative Example 3)

[0192] (1) Preparation of positive electrode

[0193] LiNi 0.9 Mn 0.05 Co 0.05 The O2 positive electrode active material, the silver-germanium sulfide solid electrolyte Li6PS5Cl, and the conductive material were mixed at a weight ratio of 85:0.6 using a mixer (available from Hosokawa Micron's Nobailta MINI) at 2000 rpm for 7 minutes to prepare a mixture.

[0194] A solid electrolyte mixture, Ketjen Black conductive material, silver sulfide germanite-type solid electrolyte Li6PS5Cl, and polytetrafluoroethylene binder were added to xylene solvent at a weight ratio of 85.6:0.4:13:1 and mixed at 2000 rpm for 1 minute using a THINKY MIXER. This process was repeated 10 times to prepare the binder mixture.

[0195] The extruded product was prepared by extruding the binder mixture at 60°C using an extruder, wherein the screw speed was 100 rpm and the torque condition was 2 during extrusion.

[0196] The extruded product was crushed at 10,000 rpm for 2 minutes.

[0197] Subsequently, the obtained product was subjected to rolling pressing using two rollers at 60°C and a roller speed of 3 rpm to prepare a sheet-like positive electrode active material layer. The thickness of the prepared sheet-like positive electrode active material layer was 130 μm. The prepared positive electrode active material layer was in a state where the composite active material was embedded in a binder matrix. The composite active material included a core and a conductive material located on the surface of the core. The core included the positive electrode active material and an electrolyte surrounding the surface of the positive electrode active material. The positive electrode was prepared by placing the positive electrode active material layer on an aluminum positive electrode current collector.

[0198] All-solid-state battery cells were manufactured in the same manner as in Example 1 using a positive electrode, a negative electrode from Example 1, and a solid electrolyte from Example 1.

[0199] (Comparative Example 4)

[0200] (1) Preparation of positive electrode

[0201] LiNi 0.9 Mn 0.05 Co 0.05 The O2 positive electrode active material and the silver-germanium sulfide solid electrolyte Li6PS5Cl were mixed at a weight ratio of 85:13.6 using a mixer (available from Hosokawa Micron's Nobailta MINI) at 2000 rpm for 2 minutes to prepare an electrolyte mixture.

[0202] The electrolyte mixture and Ketjen Black conductive material were mixed at a weight ratio of 98.6:0.4 using a mixer (NobailtaMINI) at a stirring speed of 2000 rpm for 5 minutes to prepare the mixture.

[0203] The mixture and PTFE adhesive were mixed at a weight ratio of 99:1 using a mixer (THINKY MIXER) at 2000 rpm for 1 minute, and repeated 10 times to prepare the adhesive mixture.

[0204] The extruded product was prepared by extruding the binder mixture at 60°C using an extruder, wherein the screw speed was 100 rpm and the torque condition was 2 during extrusion.

[0205] The extruded product was crushed at 10,000 rpm for 2 minutes.

[0206] Subsequently, the obtained product was subjected to rolling pressing using two rollers at 60°C and a roller speed of 3 rpm to prepare a sheet-like positive electrode active material layer. The thickness of the prepared sheet-like positive electrode active material layer was 200 μm. The prepared positive electrode active material layer was in a state where the composite active material was embedded in a binder matrix. The composite active material included a core and a conductive material located on the surface of the core. The core included the positive electrode active material and an electrolyte surrounding the surface of the positive electrode active material.

[0207] The positive electrode is prepared by placing the positive electrode active material layer on the aluminum positive electrode current collector.

[0208] All-solid-state battery cells were manufactured in the same manner as in Example 1 using a positive electrode, a negative electrode from Example 1, and a solid electrolyte from Example 1.

[0209] The amounts of positive electrode active material, binder matrix, electrolyte and conductive material in the positive electrodes prepared by Examples 1 to 7 and Comparative Examples 1 to 3 are shown in Table 1.

[0210] Table 1

[0211]

[0212] Example 1) Evaluation of discharge capacity and initial efficiency

[0213] The all-solid-state battery cells according to Examples 1 to 7 and Comparative Examples 1 to 4 were charged and discharged once at 0.1C, and the charging capacity and discharging capacity were measured. The measured discharge capacity results are shown in Table 2.

[0214] In addition, the ratio of discharge capacity to charge capacity was measured, and the results are presented as the initial efficiency in Table 2.

[0215] Table 2

[0216]

[0217] As shown in Table 2 above, the all-solid-state battery cells of Examples 1 to 7, which utilize sheet-type positive electrodes in which composite active materials are embedded in a binder matrix, exhibit high discharge capacity and excellent initial efficiency. The composite active material includes a core and an electrolyte surrounding the surface of the core. The core includes a positive electrode active material and a conductive material attached to the surface of the positive electrode active material.

[0218] On the other hand, Comparative Example 1, which uses a sheet-type positive electrode comprising a positive electrode active material and a conductive material, exhibits low discharge capacity and initial efficiency, while Comparative Example 2, which uses a sheet-type positive electrode comprising a positive electrode active material and an electrolyte, exhibits significantly reduced discharge capacity and initial efficiency.

[0219] Furthermore, Comparative Example 3, which uses a solvent to prepare a sheet-type positive electrode, exhibits low discharge capacity and initial efficiency.

[0220] In addition, Comparative Example 4, which utilizes a sheet-type positive electrode in which the composite active material is embedded in a binder matrix, exhibits very low discharge capacity and initial efficiency. The composite active material includes a core and a conductive material surrounding the surface of the core. The core includes a positive electrode active material and an electrolyte attached to the surface of the positive electrode active material.

[0221] While the invention has been described in conjunction with examples which are now considered practical embodiments, it will be understood that the invention is not limited to the disclosed embodiments, but rather is intended to cover a variety of modifications and equivalent arrangements included within the spirit and scope of the appended claims.

Claims

1. A positive electrode for all-solid-state batteries, comprising: Adhesive matrix; and Composite active substances embedded in the adhesive matrix, The composite active material includes: a core, the core comprising a positive electrode active material and a conductive material attached to the surface of the positive electrode active material; And an electrolyte layer disposed on the surface of the core.

2. The positive electrode for an all-solid-state battery according to claim 1, wherein the binder matrix is ​​composed of a fibrous binder.

3. The positive electrode for an all-solid-state battery according to claim 2, wherein the binder comprises polytetrafluoroethylene, polyvinyl alcohol, polyvinylidene fluoride, or a combination thereof.

4. The positive electrode for an all-solid-state battery according to claim 1, wherein the amount of the binder matrix is ​​from 0.1% to 10% by weight based on the total weight of the positive electrode.

5. The positive electrode for an all-solid-state battery according to claim 1, wherein the amount of the conductive material is from 0.1% to 10% by weight based on the total weight of the positive electrode.

6. The positive electrode for an all-solid-state battery according to claim 1, wherein the amount of electrolyte is from 3% to 20% by weight based on the total weight of the positive electrode.

7. The positive electrode for an all-solid-state battery according to claim 1, wherein the amount of the conductive material is less than the amount of the electrolyte.

8. The positive electrode for an all-solid-state battery according to claim 1, wherein the electrolyte comprises a solid electrolyte.

9. The positive electrode for an all-solid-state battery according to claim 1, wherein the positive electrode is a sheet-type positive electrode.

10. The positive electrode for an all-solid-state battery according to claim 1, wherein the positive electrode comprises a binder matrix in which the composite active material is embedded.

11. The positive electrode for an all-solid-state battery according to claim 1, wherein the conductive material comprises a carbon-based material, a metal-based material, a conductive polymer, or a combination thereof.

12. The positive electrode for an all-solid-state battery according to claim 1, wherein the positive electrode is prepared by mixing the positive electrode active material and the conductive material to prepare a mixture; The mixture and the electrolyte are mixed to prepare an electrolyte mixture; The electrolyte mixture, the conductive material, the electrolyte, and the binder are mixed to prepare a binder mixture; and The adhesive mixture is extruded.

13. The positive electrode for an all-solid-state battery according to claim 1, wherein the positive electrode has a thickness of 70 μm to 500 μm.

14. All-solid-state batteries, including: The positive electrode according to any one of claims 1 to 13; negative electrode; as well as A solid electrolyte layer is disposed between the positive electrode and the negative electrode.

15. The all-solid-state battery according to claim 14, wherein the solid electrolyte is a sulfide-based solid electrolyte.

16. The all-solid-state battery of claim 14, wherein the all-solid-state battery further comprises a lithium-containing layer formed between the current collector and the negative electrode coating during initial charging.

Images